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1.  Are adrenaline autoinjectors fit for purpose? A pilot study of the mechanical and injection performance characteristics of a cartridge-versus a syringe-based autoinjector 
Adrenaline autoinjectors (AAIs) are prescribed to facilitate the intramuscular administration of adrenaline in patients diagnosed with life-threatening anaphylaxis. This pilot study investigated the injection and functional properties of two AAIs (deploying different delivery systems) under standard conditions, after dynamic and mechanical stresses, and in the presence of denim.
The differences between a cartridge-based AAI (EpiPen® Junior) and a syringe-based AAI (Anapen® Junior) were assessed using three sets of tests. Test 1: under standard conditions, the injection depth and dose were measured in ballistic gelatine (a validated tissue simulant). Test 2: before the safety cap removal and activation forces were measured, AAIs were subjected to either of two preconditioning tests: 1) free-fall drop test; or 2) static load (ie, 400 N, equivalent to 40 kg weight) test; or 3) no preconditioning. Test 3: under standard conditions, injection properties into ballistic gelatine in the presence and absence of denim were investigated. Statistical analyses were performed using the Student’s t-test or Welch’s test.
The maximum depth of delivery was significantly greater with cartridge AAI (n = 4, mean 21.09 ± 2.54 mm) than with syringe AAI (n = 5; mean 11.64 ± 0.80 mm; P = 0.003). After 2.5 seconds, cartridge AAI (n = 4) discharged significantly more dose than syringe AAI (n = 3; 74.3% versus 25.7% of total dose; P = 0.001). Both cartridge and syringe AAI withstood the free-fall drop test, but almost all devices failed to activate following the static load test. Under standard conditions, significantly less force was required to remove the safety cap of cartridge AAI than syringe AAI (both n = 15; mean 9.56 ± 2.36 N versus 20.23 ± 6.61 N, respectively; P < 0.001), but a significantly greater activation force was required for cartridge AAI than syringe AAI (mean 23.01 ± 3.96 N versus 8.06 ± 0.51 N, respectively; P < 0.001). The presence of denim did not alter the activation force or effective needle length of either of the AAIs.
Cartridge AAI appears significantly more capable of consistently and rapidly delivering a clinically relevant dose of intramuscular adrenaline than syringe AAI. However, both devices showed shortcomings in their ability to sustain mechanical stress similar to that which is likely over their shelf life, and as such, may not be fit for life-saving purpose.
PMCID: PMC3047909  PMID: 21437050
anaphylaxis; intramuscular; delivery system; device
2.  Subdural spread of injected local anesthetic in a selective transforaminal cervical nerve root block: a case report 
Although uncommon, selective cervical nerve root blocks can have serious complications. The most serious complications that have been reported include cerebral infarction, spinal cord infarction, transient quadriplegia and death.
Case presentation
A 40-year-old Japanese woman with a history of severe right-sided cervical radicular pain was scheduled to undergo a right-sided C6 selective cervical nerve root block using a transforaminal approach under fluoroscopic guidance. An anterior oblique view of the C5-C6 intervertebral foramen was obtained, and a 23-gauge spinal needle, connected to the normal extension tube with a syringe filled with contrast medium, was introduced into the posterior-caudal aspect of the C5-C6 intervertebral foramen on the right side. In the anteroposterior view, the placement of the needle was considered satisfactory when it was placed no more medial than halfway across the width of the articular pillar. Although the spread of the contrast medium along the C6 nerve root was observed with right-sided C6 radiculography, the subdural flow of the contrast medium was not observed with real-time fluoroscopy. The extension tube used for the radiculography was removed from the spinal needle and a normal extension tube with a syringe filled with lidocaine connected in its place. We performed a negative aspiration test and then injected 1.5 mL of 1.0% lidocaine slowly around the C6 nerve root. Immediately after the injection of the local anesthetic, our patient developed acute flaccid paralysis, complained of breathing difficulties and became unresponsive; her respiratory pattern was uncoordinated. After 20 minutes, she regained consciousness and became alert, and her muscle strength in all four limbs returned to normal without any sensory deficits after receiving emergent cardiorespiratory support.
We believe that confirming maintenance of the appropriate needle position in the anteroposterior view by injecting local anesthetic is important for preventing central needle movement. Because the potential risk of serious complications cannot be completely eliminated during the use of any established selective cervical nerve root block procedure, preparation for an emergency airway, ventilation and cardiovascular support is indispensable in cases of high spinal cord anesthesia.
PMCID: PMC3414837  PMID: 22657834
3.  Anesthetic Cartridge System Under Evaluation 
Anesthesia Progress  1981;28(1):5-10.
The problem of glass breakage in the local anesthetic cartridge system was evaluated under laboratory conditions with a mechanical testing machine. The anticipated breakage of the glass did not occur with any frequency, as the rubber stopper produced more uniform failures of the system. The glass cartridge appeared to be quite reliable and resistant to breakage.
Local anesthetics have been used for many years to provide patients temporary freedom from pain. Local anesthetic solutions are in wide use in both dentistry and medicine and are the most frequently used drugs in dentistry. Various estimates place the number of injections at approximately one half million daily or 125 million injections per year.
These drugs and the armamentarium necessary to administer them have proven to be safe and reliable. Only rarely are there reports of sensitivity to the anesthetic solution or breakage of needles.. Sterility of the solutions has not been a problem as they are carefully processed and evaluated at the factory. Although there are sporadic reports of loss of sterility, this has been attributed to the reuse of the anesthetic cartridges on more than one patient. Monheim states “The success of the cartridge system in dentistry has been due to the sincerity, honesty, and high standards of the manufacturers in giving the profession a near-perfect product.” However, on occassion a glass cartridge will break or shatter when inserting the harpoon into the rubber stopper or even during injection. Cooley et al reported on eye injuries occurring in the dental office, one of which was due to glass from a local anesthetic cartridge that exploded and propelled particles into the patient's eye. Forrest evaluated syringes, needles, and cartridges and reported that one brand (made in Britain) fractured more often than any other, but that the fracture rate was too low to be of any consequence.
It is apparent that glass cartridges will fracture or burst from time to time. This study evaluates the cartridge system with carefully controlled laboratory procedures. The cartridges were tested under various pressures and conditions in an attempt to determine the causes of failure and when such failure may be anticipated.
PMCID: PMC2235753  PMID: 6939350
4.  Comparison of Inferior Dental Nerve Block Injections in Child Patients Using 30-Gauge and 25-Gauge Short Needles 
Anesthesia Progress  1987;34(6):215-219.
Thirty-gauge needles are generally not recommended by dental schools, yet many dentists use them. Thin needles (30 gauge) can aspirate blood, have similar deflection to thick needles (25 gauge), and resist breakage. Measurable clinical differences between inferior dental block injections using 25-gauge or 30-gauge short needles for children is addressed in this research paper. Random allocation assigned 76 cases to 30-gauge and 62 cases to 25-gauge tribeveled. Twenty-seven-gauge short needles are in routine use for inferior dental nerve block injections in our clinics. After informed written consent was obtained, inferior dental block injections were carefully administered to children (62 males and 76 females, mean age 10 years ± 3 [SD], range 4—18 years) by faculty and students in pediatric dentistry and observed by one of two trained observers. After aspiration in two planes (180°), 0.5 mL of 2% lidocaine with 1:100,000 epinephrine was deposited in the lingual block area then 1.0 mL in the inferior dental area after touching bone. Any aspirate was recorded and subjective pain scores were taken immediately using a visual analogue scale. Five minutes after the commencement of the injection, the efficacy was tested objectively by two light needle pricks of the mucosa adjacent to the cuspid. The comparability of groups as regards age and sex was verified. Half of the injections were effective at five minutes in each group. There were no significant differences in efficacy, or pain scores. Both 25- and 30-gauge groups had nine instances of slight aspiration and two instances of more marked aspirations. The overall aspiration rate was 16%. It is concluded that 25- and 30-gauge needles do not differ significantly with respect to efficacy, pain, or aspiration. Children do not think that inferior dental nerve block injections hurt very much, and there is no evidence to support a change from 25- to 30-gauge needles.
PMCID: PMC2190042  PMID: 3481519
5.  Vacuum-assisted breast biopsy: A comparison of 11-gauge and 8-gauge needles in benign breast disease 
Minimal invasive breast biopsy is standard care for the diagnosis of suspicious breast lesions. There are different vacuum biopsy (VB) systems in use. The aim of the study was to determine the differences between the 8-gauge and the 11-gauge needle with respect to a) diagnostic reliability, b) complication rate and c) subjective perception of pain when used for vacuum-assisted breast biopsy.
Between 01/2000 and 09/2004, 923 patients at St. Josefs-Hospital Wiesbaden underwent VB using the Mammotome® (Ethicon Endosurgery, Hamburg). Depending on preoperative detection, the procedure was performed under sonographic or mammographic guidance under local anaesthesia. All patients included in the study were followed up both clinically and using imaging techniques one week after the VB and a second time after a median of 41 months. Excisional biopsy on the ipsilateral breast was an exclusion criteria. Subjective pain scores were recorded on a scale of 0 – 10 (0 = no pain, 10 = unbearable pain). The mean age of the patients was 53 years (30 – 88).
123 patients were included in the study in total. 48 patients were biopsied with the 8-gauge needle and 75 with the 11-gauge needle. The use of the 8-gauge needle did not show any significant differences to the 11-gauge needle with regard to diagnostic reliability, complication rate and subjective perception of pain.
Our data show that there are no relevant differences between the 8-gauge and 11-gauge needle when used for VB. Under sonographic guidance, the use of the 8-gauge needle is recommended for firm breast tissue due to its sharp scalpel point and especially for complete removal of benign lesions. We did not find any advantages in the use of the larger 8-gauge needle compared to the 11-gauge needle in the mammography setting. The utilisation costs of the 8-gauge needle are somewhat higher.
PMCID: PMC2405782  PMID: 18489771
6.  The Incidence of Intravascular Needle Entrance during Inferior Alveolar Nerve Block Injection 
Background and aims
Dentists administer thousands of local anesthetic injections every day. Injection to a highly vascular area such as pterygomandibular space during an inferior alveolar nerve block has a high risk of intravascular needle entrance. Accidental intravascular injection of local anesthetic agent with vasoconstrictor may result in cardiovascular and central nervous system toxicity, as well as tachycardia and hypertension. There are reports that indicate aspiration is not performed in every injection. The aim of the present study was to assess the incidence of intravascular needle entrance in inferior alveolar nerve block injections.
Materials and methods
Three experienced oral and maxillofacial surgeons performed 359 inferior alveolar nerve block injections using direct or indirect techniques, and reported the results of aspiration. Aspirable syringes and 27 gauge long needles were used, and the method of aspiration was similar in all cases. Data were analyzed using t-test.
15.3% of inferior alveolar nerve block injections were aspiration positive. Intravascular needle entrance was seen in 14.2% of cases using direct and 23.3% of cases using indirect block injection techniques. Of all injections, 15.8% were intravascular on the right side and 14.8% were intravascular on the left. There were no statistically significant differences between direct or indirect block injection techniques (P = 0.127) and between right and left injection sites (P = 0.778).
According to our findings, the incidence of intravascular needle entrance during inferior alveolar nerve block injection was relatively high. It seems that technique and maneuver of injection have no considerable effect in incidence of intravascular needle entrance.
PMCID: PMC3533637  PMID: 23285329
Inferior alveolar nerve; injection; local anesthesia
7.  Assessment of Patient Pain Experience during Intravitreal 27-Gauge Bevacizumab and 30-Gauge Ranibizumab Injection 
To compare pain scores of patients during intravitreal 27-gauge bevacizumab and 30-gauge ranibizumab injection procedures.
Seventy eyes of 70 patients who had not previously undergone intravitreal anti-vascular endothelial growth factor therapy were included in this study. Thirty-five patients received ranibizumab and 35 patients received bevacizumab. The diagnoses of the patients were: 27 age related macular degeneration, 15 diabetic macular edema, 9 diabetic vitreous hemorrhage, 6 central retinal vein occlusion, 11 branch retinal vein occlusion and 2 central serous chorioretinopathy. Bevacizumab (1.25 mg/0.05 mL) was injected into the vitreous cavity using a 27-gauge needle, and ranibizumab (0.5 mg/0.05 mL) was injected with 30-gauge needle. Patients were asked just after the injection to rate their perceived pain during the injection using the visual analogue scale (VAS) of 0 (no pain) to 10 (unbearable/worst pain). The average of these scores was used as the primary outcome.
The VAS pain scores in the ranibizumab and bevacizumab groups were 1.06 ± 0.91 (range, 0 to 3) and 1.94 ± 1.55 (range, 0 to 7), respectively, a significant difference (p = 0.005). Patients <65 and ≥65 years of age in both the ranibizumab and bevacizumab groups were then compared. For patients <65, there was a significant difference in the average VAS pain scores between groups (p = 0.003). However, for patients ≥65 years, there was not a significant difference in the average VAS pain scores between groups (p = 0.238). Female and male patients in both ranibizumab and bevacizumab groups were also compared. For female patients, there was a significant difference in the average VAS pain scores between groups (p = 0.016), although not for male patients (p = 0.078).
Thirty-gauge intravitreal injection is more comfortable than 27-gauge injection. Injection of bevacizumab with 30-gauge needle syringes may be more tolerable for patients.
PMCID: PMC4446560  PMID: 26028948
Bevacizumab; Intravitreal injections; Pain; Ranibizumab; Visual analogue scale
In the preceding pages we have submitted evidence which shows that a simple intratracheal injection of a solution in a normally breathing rabbit penetrates within a few seconds to the alveoli, chiefly those of the left lower lobe; that absorption is rapid and well maintained; and that the procedure may be repeated effectively a number of times even with a substance like adrenalin which decreases absorption. It was also shown that absorption of adrenalin from the lung could be obtained at a time when double the dose given intramuscularly exerted no blood pressure effect whatever, and that absorption could still take place after the development of pulmonary edema, when there was an undoubted dilution of the injected solution with a serum-containing liquid and when a diminution of the absorptive field had occurred. The solution injected, after reaching the alveoli, is probably largely taken up by the capillaries of the pulmonary veins. This is indicated by the great rapidity with which an intratracheal injection of adrenalin may cause a rise of blood pressure. In numerous instances, for example, the pressure began to rise less than 5 seconds after the completion of an injection, equaling and even surpassing in rapidity of effect an intramuscular injection. Absorption by the lymphatics probably plays a secondary part, an assumption rendered all themore likely if we consider that lymph nodes are interpolated in the lymphatic pulmonary path, where the bed of the lymph stream becomes greatly widened and the current slowed. Injection into the lungs, however, offers another advantage due to the vascular arrangement of the absorbing field which could be of value therapeutically. Absorption of liquids injected into the lung probably takes place largely through the capillaries of the pulmonary veins; to a slight extent possibly through the capillaries of the bronchial veins which empty partly into the pulmonary veins, partly into the azygos veins; and probably some absorption occurs also through the lymphatics. By far the larger proportion of the absorbed material will thus be rapidly delivered to the left auricle and then to the left ventricle. At each succeeding systole, as long as absorption continues, a fraction of the drug will be driven into the coronary arteries and be able to affect the musculature of the cardiac pump. This fact ought to render the procedure of intratracheal injection a valuable method when it becomes imperative to stimulate a suddenly failing heart as promptly as possible by drugs of the digitalis group. Intratracheal injection is perhaps better under the conditions mentioned than the intravenous route, for the surface veins cannot always be entered with promptness and certainty even under fairly normal conditions, and in cases of cardiac weakness the difficulties will be measurably increased, while an intratracheal injection can be carried out with ease. Moreover, it is legitimate to expect that some absorption will take place from the lung alveoli as long as the heart-lung circulation persists, no matter how feebly, and that thus some of the drug will reach the heart to act on this structure itself more promptly perhaps than when the drug is administered successfully through surface veins. As far as the intramuscular route is concerned, we have shown that the intratracheal injection of adrenalin gives prompt though diminished absorption at a time when double the dose intramuscularly exerts no blood pressure effect whatever. The technical difficulties of giving an intratracheal injection in animals are slight. Tracheotomy as practised by us in the present series of experiments is not necessary, for the injection may be given into the intact trachea without exposure of the trachea. The hypodermic needle is inserted through the skin about 1 cm. below the larynx in a slanting caudad direction; the entrance of the needle into the trachea is readily felt. The injection should not be so rapid that the injected solution fills the entire tracheal lumen, but it should flow down the sides of the trachea. If the lumen is entirely filled, an expiration may drive some of the injected liquid into the larynx causing cough. In our experiments each injection of about 0.5 cc. consumed approximately 5 seconds. In the human subject no data are available as far as our knowledge goes, but a priori it would seem that an intratracheal injection is almost as simple as in the lower animals. The free hypodermic needle could be inserted into the tracheal lumen immediately below the cricoid cartilage. The needle itself should preferably be connected with the syringe by a short length of rubber tubing to minimize the danger of breaking the needle by a sudden move of the patient. The amount of the solution should not be too small, so that at least a fraction of it may reach the alveoli as promptly as possible; 3 to 5 cc. probably would suffice. Insertion of the needle in the locality mentioned would puncture the isthmus of the thyroid, but this is of no significance, especially when the procedure is employed in cases of cardiac failure where the gravity of the condition would warrant incurring much heavier risks than a slight bleeding from the thyroidal isthmus. In conclusion it may be said that the incorporation of drugs by intratracheal injection, while not as generally applicable as other methods, nevertheless has advantages which warrant its use also in human therapeutics.
PMCID: PMC2125455  PMID: 19868021
9.  A Micro-Advancer Device for Vitreal Injection and Retinal Recording and Stimulation 
Experimental eye research  2011;93(5):767-770.
A micro-advancer device that positions a narrow-gauge needle within the vitreous humor of the rat eye is described. The device is compact, simple and inexpensive to manufacture. It consists of an outer guard needle and an inner injection needle that is advanced through the guard needle. With the rat held in a stereotaxic holder and the globe fixed to a stabilizing ring, the outer 25-gauge guard needle is advanced through the sclera using a standard micromanipulator. The inner 31-gauge injection needle is then advanced through the guard needle with a manually controlled leadscrew and carriage mechanism. The inner injection needle is attached to a Hamilton syringe and can be positioned to within microns of the retinal surface under visual observation through a microscope. The injection needle is fixed to the device by a quick-release clamp on the carriage and can be rapidly exchanged while the guard needle remains in place in the vitreous. This permits different solutions to be injected sequentially into the vitreous humor. Recording electrodes, stimulating electrodes, and optical fibers can also be advanced through the guard needle and positioned accurately near the retinal surface or within the retina.
PMCID: PMC3233358  PMID: 21884697
Micro-advancer device; vitreous humor; retina; intraocular injection; multiple injections; recording electrode; stimulating electrode; inexpensive
10.  Effect of Needle Design on Pain From Dental Local Anesthetic Injections 
Anesthesia Progress  2015;62(1):2-7.
The purpose of this randomized, double-blind clinical study was to evaluate the effectiveness of a larger-bore compared with a standard-bore dental local anesthetic needle of the same gauge in reducing pain during inferior alveolar (IA) and long buccal (LB) nerve block injections. Twenty active duty military or Department of Defense beneficiaries undergoing dental treatment were anesthetized using a split-mouth design with 4 anesthetic dental injections. Both sides of the mouth received IA nerve block and LB nerve injections, one using the 27-gauge large-bore Septoject XL needle and other using a 27-gauge standard-bore Septoject needle. Patients rated the pain experienced with each method using a visual analogue scale (VAS). The IA injection mean VAS score and standard deviation were 38.9 ± 22.7 mm and 37.1 ± 22.4 mm, respectively, for the larger and standard-bore needles. The LB injection mean VAS score and standard deviation were 33.5 ± 22.8 mm and 35.1 ± 19.6 mm, respectively, for the larger and standard-bore needles. The data were analyzed with a paired t test (α = .05). No significant difference was found between the IA (P = .70) or LB injections (P = .73). The use of a larger-bore 27-gauge needle did not reduce pain on injection compared with the standard-bore 27-gauge needle.
PMCID: PMC4389552  PMID: 25849467
Bore size; Needle; Pain
11.  Initial Injection Pressure for Dental Local Anesthesia: Effects on Pain and Anxiety 
Anesthesia progress  2005;52(3):95-101.
This study quantitatively assessed injection pressure, pain, and anxiety at the start of injection of a local anesthetic into the oral mucosa, and confirmed the relationship between injection pressure and pain, as well as between injection pressure and anxiety. Twenty-eight healthy men were selected as subjects and a 0.5-inch (12 mm) 30-gauge disposable needle attached to a computer-controlled local anesthetic delivery system (the Wand) was used. A 0.5 mL volume of local anesthetic solution was injected submucosally at a speed of either 30 or 160 s/mL. Three seconds after the start of local anesthetic injection, injection pressure was measured and pain and anxiety were assessed. Injection pressure was measured continuously in real time by using an invasive sphygmomanometer and analytical software, and pain was assessed on the Visual Analogue Scale and anxiety on the Faces Anxiety Scale. A significant correlation was evident between injection pressure and pain (rs = .579, P = .00124) and between intensity of injection pressure and state anxiety (rs = .479, P = .00979). It is therefore recommended that local anesthetic be injected under low pressure (less than 306 mm Hg) to minimize pain and anxiety among dental patients.
PMCID: PMC1586792  PMID: 16252739
Local anesthetic initial injection pressure; Pain; Anxiety
12.  Coronary Artery Ligation and Intramyocardial Injection in a Murine Model of Infarction 
Mouse models are a valuable tool for studying acute injury and chronic remodeling of the myocardium in vivo. With the advent of genetic modifications to the whole organism or the myocardium and an array of biological and/or synthetic materials, there is great potential for any combination of these to assuage the extent of acute ischemic injury and impede the onset of heart failure pursuant to myocardial remodeling.
Here we present the methods and materials used to reliably perform this microsurgery and the modifications involved for temporary (with reperfusion) or permanent coronary artery occlusion studies as well as intramyocardial injections. The effects on the heart that can be seen during the procedure and at the termination of the experiment in addition to histological evaluation will verify efficacy.
Briefly, surgical preparation involves anesthetizing the mice, removing the fur on the chest, and then disinfecting the surgical area. Intratracheal intubation is achieved by transesophageal illumination using a fiber optic light. The tubing is then connected to a ventilator. An incision made on the chest exposes the pectoral muscles which will be cut to view the ribs. For ischemia/reperfusion studies, a 1 cm piece of PE tubing placed over the heart is used to tie the ligature to so that occlusion/reperfusion can be customized. For intramyocardial injections, a Hamilton syringe with sterile 30gauge beveled needle is used. When the myocardial manipulations are complete, the rib cage, the pectoral muscles, and the skin are closed sequentially. Line block analgesia is effected by 0.25% marcaine in sterile saline which is applied to muscle layer prior to closure of the skin. The mice are given a subcutaneous injection of saline and placed in a warming chamber until they are sternally recumbent. They are then returned to the vivarium and housed under standard conditions until the time of tissue collection. At the time of sacrifice, the mice are anesthetized, the heart is arrested in diastole with KCl or BDM, rinsed with saline, and immersed in fixative. Subsequently, routine procedures for processing, embedding, sectioning, and histological staining are performed.
Nonsurgical intubation of a mouse and the microsurgical manipulations described make this a technically challenging model to learn and achieve reproducibility. These procedures, combined with the difficulty in performing consistent manipulations of the ligature for timed occlusion(s) and reperfusion or intramyocardial injections, can also affect the survival rate so optimization and consistency are critical.
PMCID: PMC3197029  PMID: 21673649
13.  Blockade of the mental nerve for lower lip surgery as a safe alternative to general anesthesia in two very old patients 
Regional anesthesia is gaining popularity with anesthesiologists as it offers superb postoperative analgesia. However, as the sole anesthetic technique in high-risk patients in whom general anesthesia is not preferred, some regional anesthetic possibilities may be easily overlooked. By presenting two cases of very old patients with considerable comorbidities, we would like to bring the mental nerve field block under renewed attention as a safe alternative to general anesthesia and to achieve broader application of this simple nerve block.
Patients and methods
Two very old male patients (84 and 91 years) both presented with an ulcerative lesion at the lower lip for which surgical removal was scheduled. Because of their considerable comorbidities and increased frailty, bilateral blockade of the mental nerve was considered superior to general anesthesia. As an additional advantage for the 84-year-old patient, who had a pneumonectomy in his medical history, the procedure could be safely performed in a beach-chair position to prevent atelectasis and optimize the ventilation/perfusion ratio of the single lung. The mental nerve blockades were performed intraorally in a blind fashion, after eversion of the lip and identifying the lower canine. A 5 mL syringe with a 23-gauge needle attached was passed into the buccal mucosa until it approximated the mental foramen, where 2 mL of lidocaine 2% with adrenaline 1:100.000 was injected. The other side was anesthetized in a similar fashion.
Both patients underwent the surgical procedure uneventfully under a bilateral mental nerve block and were discharged from the hospital on the same day.
A mental nerve block is an easy-to-perform regional anesthetic technique for lower lip surgery. This technique might be especially advantageous in the very old, frail patient.
PMCID: PMC4437613  PMID: 25999760
intraoral; regional anesthesia; percutaneous; ultrasound; mental nerve block
14.  An analysis of the effectiveness of two topical anesthetics. 
Anesthesia Progress  1990;37(6):290-292.
This study compared the effectiveness of topical benzocaine 20%, lidocaine 5%, and a placebo in reducing the pain caused by needle insertion when the medicament was placed in the mucobuccal fold above the maxillary canine eminence. Both topical anesthetics and the placebo were randomly tested against each other bilaterally. For uniformity the agents were left in place for three minutes before needle insertion. A 27 gauge short needle mounted on an aspirating syringe was then inserted just past the bevel. Each subject rated the degree of pain on a visual analogue scale 100 mm in length. A pulse oximeter was used to record the heart rate. The results indicate that both topical anesthetics are significantly better than the placebo in reducing pain caused by needle insertion, although no statistically significant differences were found between the two topical anesthetics. Statistically significant differences in heart rate were seen, but these differences were not clinically significant. It is concluded that benzocaine 20% and lidocaine 5% significantly reduce the pain during needle insertion.
PMCID: PMC2162554  PMID: 2097909
15.  Therapeutic effects of adenovirus-mediated growth and differentiation factor-5 in a mice disc degeneration model induced by annulus needle puncture 
The therapeutic strategies that have thus far been employed for the treatment of intervertebral disc degeneration (IDD) have focused on relieving the symptoms, while reversal of the degeneration remains an important challenge for the effective treatment of IDD. Growth and differentiation factor-5 (GDF5), of which deficiency leads to early disc degeneration changes, has the potential to increase proliferation of disc cells and expression of extracellular matrix proteins.
To develop a lumbar disc degeneration model in mice and determine the effect of adenoviral GDF5 gene therapy.
Compare the degeneration changes of discs punctured by different size needles to develop a mice lumbar disc degeneration model. Evaluate the effects of in vivo gene therapy for the mice disc degeneration model by an adenoviral vector carrying GDF5 gene.
A lumbar disc degeneration model was developed by needle punctures to the discs in Balb/c mice. Afterwards, a gene therapy treatment to disc degeneration was evaluated. Two of the mice lumbar discs were randomly chosen to be punctured by a 30- gauge needle and then injected with adenovirus that had been engineered to express either the luciferase gene (Ad-Luc) or the GDF5 gene (Ad-GDF5). Animals were analyzed by bioluminescent imaging, radiographic and MRI scanning, then sacrificed at 1-, 2-, 4-, or 8- week post operation and subjected to histological and biochemical assays.
By the detection of T2-weighted MRI scanning and histological study, the degeneration was found in all of the discs punctured by different size needles. But the development of the degeneration in the discs injured by 30-gauge needle was more reliable and moderate compared with other groups. The detection of luciferase activity by bioluminescent imaging revealed that adenovirus survived and the introduced genes were expressed over 6 weeks after injection. There were no T2-weighted MRI signals in either the Ad-Luc or Ad-GDF5 injected mice up to 4 weeks post operation. At 6 and 8 weeks, T2-weighted signals were detected in the Ad-GDF5 group, but none in the Ad-Luc control group. The percent disc height index (%DHI) was significantly decreased (~ 20%) by 1 week following injury in both groups, indicating the development of disc degeneration. At 2 weeks, the %DHI in the mice injected with Ad-GDF5 increased significantly compared with that of the mice injected with Ad-Luc group; the increase was sustained for the rest of experiment period. The disc histology treated with Ad-GDF5 was improved compared with that in control group. Glycosaminoglycan (GAG) levels were significantly decreased in the Ad-Luc injection group since 2 weeks after injury, and the DNA content had diminished by 4 weeks after the operation. In contrast, in the discs injected with Ad-GDF5, there was no decrease in the GAG and DNA levels following injury throughout the 8 weeks treatment period.
Disc degeneration animal model can be developed by using needle puncture to the discs in mice. The adenovirus is an effective vehicle for gene delivery with rapid and prolonged expression of target protein, and resulting improvement in markers of disc degeneration. Ad-GDF5 gene therapy could restore the functions of injured discs and has the potential to be an effective treatment.
PMCID: PMC2818300  PMID: 19926342
Intervertebral disc; degeneration; gene therapy; growth factor
16.  A blunt needle (Epimed®) does not eliminate the risk of vascular penetration during transforaminal epidural injection 
Surgical Neurology International  2013;4(Suppl 5):S404-S406.
Transforaminal epidural injection of local anesthetics and corticosteroids is a common practice in patients with radicular pain. However, serious morbidity has also been reported, which can be attributed to an arterial or venous injection of the medication especially particulate glucocorticoid preparations. Using a blunt needle in contrast to sharp needle has been suggested to reduce this risk in a study on animals.
Case Description:
We present a 59-year-old female with L5 lumbar radicular symptoms and left L5-S1 foraminal narrowing who underwent transforaminal epidural injection with fluoroscopic guidance using a 22-gauge blunt curved needle (Epimed®, Johnstown, NY). Intravascular needle placement was detected during real-time contrast injection under live fluoroscopy after a negative aspiration and local anesthetic test dose. The needle was slightly withdrawn and correct distribution of the contrast was confirmed along the target nerve root and into the epidural space.
This case report discusses vascular penetration utilizing an Epimed® blunt needle to perform transforaminal injections in a clinical setting. This topic was previously discussed in earlier animal studies. We also reemphasize that neither negative aspiration or local anesthetic test doses are reliable techniques to ensure the safety of transforaminal epidural injections.
PMCID: PMC3841942  PMID: 24340239
Blunt needle; fluoroscopy; intravascular penetration; radicular pain; transforaminal epidural injection
17.  Impact of passing mesenchymal stem cells through smaller bore size needles for subsequent use in patients for clinical or cosmetic indications 
Numerous preclinical and clinical studies have investigated the regenerative potential and the trophic support of mesenchymal stem cells (MSCs) following their injection into a target organ. Clinicians favor the use of smallest bore needles possible for delivering MSCs into vascular organs like heart, liver and spleen. There has been a concern that small needle bore sizes may be detrimental to the health of these cells and reduce the survival and plasticity of MSCs.
In this report, we aimed to investigate the smallest possible bore size needle which would support the safe delivery of MSCs into various tissues for different clinical or cosmetic applications. To accomplish this we injected cells via needle sizes 24, 25 and 26 G attached to 1 ml syringe in the laboratory and collected the cells aseptically. Control cells were ejected via 1 ml syringe without any needle. Thereafter, the needle ejected cells were cultured and characterized for their morphology, attachment, viability, phenotypic expression, differentiation potential, cryopreservation and in vivo migration abilities. In the second phase of the study, cells were injected via 26 G needle attached to 1 ml syringe for 10 times.
Similar phenotypic and functional characteristics were observed between ejected and control group of cells. MSCs maintained their cellular and functional properties after single and multiple injections.
This study proves that 26 G bore size needles can be safely used to inject MSCs for clinical/therapeutics purposes.
PMCID: PMC3543333  PMID: 23171323
Bone Marrow Mesenchymal stem cells (BM-MSC); Differentiation; Cell migration needle bore size; MSC transplantation/infusion
18.  Improved distribution of small molecules and viral vectors in the murine brain using a hollow fiber catheter 
Journal of neurosurgery  2007;107(3):568-577.
A hollow fiber catheter was developed to improve the distribution of drugs administered via direct infusion into the central nervous system (CNS). It is a porous catheter that significantly increases the surface area of brain tissue into which a drug is infused.
Dye was infused into the mouse brain through convection-enhanced delivery (CED) using a 28-gauge needle compared with a 3-mm-long hollow fiber catheter. To determine whether a hollow fiber catheter could increase the distribution of gene therapy vectors, a recombinant adenovirus expressing the firefly luciferase reporter was injected into the mouse striatum. Gene expression was monitored using in vivo bioluminescent imaging. To assess the distribution of gene transfer, an adenovirus expressing green fluorescent protein was injected into the striatum using a hollow fiber catheter or a needle.
Hollow fiber catheter—mediated infusion increased the volume of brain tissue labeled with dye by 2.7 times relative to needle-mediated infusion. In vivo imaging revealed that catheter-mediated infusion of adenovirus resulted in gene expression that was 10 times greater than that mediated by a needle. The catheter appreciably increased the area of brain transduced with adenovirus relative to a needle, affecting a significant portion of the injected hemisphere.
The miniature hollow fiber catheter used in this study significantly increased the distribution of dye and adenoviral-mediated gene transfer in the mouse brain compared with the levels reached using a 28-gauge needle. Compared with standard single-port clinical catheters, the hollow fiber catheter has the advantage of millions of nanoscale pores to increase surface area and bulk flow in the CNS. Extending the scale of the hollow fiber catheter for the large mammalian brain shows promise in increasing the distribution and efficacy of gene therapy and drug therapy using CED.
PMCID: PMC2615393  PMID: 17886557
adenovirus; catheter; convection-enhanced delivery; gene therapy; glioma; in vivo imaging; mouse
19.  Paracetamol, Ondansetron, Granisetron, Magnesium Sulfate and Lidocaine and Reduced Propofol Injection Pain 
Propofol is a most widely used intravenous anesthetic drug. One of its most common complications is the pain upon injection; therefore, different methods, with various effects, have been proposed in order to alleviate the pain.
This study investigates the effects of paracetamol, ondansetron, granisetron, magnesium sulfate and lidocaine drugs on reducing the pain of propofol injection during anesthetic induction. Also, the hemodynamic changes will be analyzed.
Patients and Methods:
This is an interventional study containing 336 patients underwent elective orthopedic surgeries in Educational Hospitals of Mashhad University, using systematic sampling, the patients were divided into six groups. A 20-gauge needle was inserted into a venous vessel in the back of the hand and 100 cc of Ringer serum was injected into the vein, which was applied proximal to the injection site. Afterwards, paracetamol 2 mg/kg (group p), magnesium sulfate 2 mmol (group M), ondansetron 4 mg (group O), granisetron 2 mg (group G), lidocaine 40 mg (group L) and 5 cc saline (group S) were injected into the vessel, after 60 seconds, the tourniquet was opened. One quarter of the total dose of propofol (2.5 mg/kg) was injected with a flow rate of 4 mg/sec and then the injection pain was measured. Finally, the fentanyl (2 µg/kg), atracurium 0.5 mg/kg, and the remaining dose of propofol were injected and the vital signs were recorded before the administration of propofol and 1, 3, 5 and 10 minutes after the propofol injection.
The six groups did not significantly differ, regarding their gender, weight or age. Propofol injection pain was less in L and G groups, in comparison with the others (P ≤ 0.001). By analyzing the hemodynamic changes, it was observed that the least amount of change in mean arterial pressure was observed in the paracetamol group.
The reduction of propofol injection pain was observed by using medications (in comparison with normal saline), but it was more significant in groups G and L. Moreover, Hypotension was higher in groups S and G and it was lessened in group P.
PMCID: PMC4005449  PMID: 24829787
Acetaminophen; Magnesium Sulfate; Ondansetron; Granisetron; Lidocaine
20.  Changes in HIV Incidence among People Who Inject Drugs in Taiwan following Introduction of a Harm Reduction Program: A Study of Two Cohorts 
PLoS Medicine  2014;11(4):e1001625.
Kenrad Nelson and colleagues report on the association between HIV incidence and exposure to a national harm-reduction program among people who inject drugs in Taiwan.
Please see later in the article for the Editors' Summary
Harm reduction strategies for combating HIV epidemics among people who inject drugs (PWID) have been implemented in several countries. However, large-scale studies using sensitive measurements of HIV incidence and intervention exposures in defined cohorts are rare. The aim of this study was to determine the association between harm reduction programs and HIV incidence among PWID.
Methods and Findings
The study included two populations. For 3,851 PWID who entered prison between 2004 and 2010 and tested HIV positive upon incarceration, we tested their sera using a BED HIV-1 capture enzyme immunoassay to estimate HIV incidence. Also, we enrolled in a prospective study a cohort of 4,357 individuals who were released from prison via an amnesty on July 16, 2007. We followed them with interviews at intervals of 6–12 mo and by linking several databases. A total of 2,473 participants who were HIV negative in January 2006 had interviews between then and 2010 to evaluate the association between use of harm reduction programs and HIV incidence. We used survival methods with attendance at methadone clinics as a time-varying covariate to measure the association with HIV incidence. We used a Poisson regression model and calculated the HIV incidence rate to evaluate the association between needle/syringe program use and HIV incidence. Among the population of PWID who were imprisoned, the implementation of comprehensive harm reduction programs and a lower mean community HIV viral load were associated with a reduced HIV incidence among PWID. The HIV incidence in this population of PWID decreased from 18.2% in 2005 to 0.3% in 2010. In an individual-level analysis of the amnesty cohort, attendance at methadone clinics was associated with a significantly lower HIV incidence (adjusted hazard ratio: 0.20, 95% CI: 0.06–0.67), and frequent users of needle/syringe program services had lower HIV incidence (0% in high NSP users, 0.5% in non NSP users). In addition, no HIV seroconversions were detected among prison inmates.
Although our data are affected by participation bias, they strongly suggest that comprehensive harm- reduction services and free treatment were associated with reversal of a rapidly emerging epidemic of HIV among PWID.
Please see later in the article for the Editors' Summary
Editors' Summary
About 35 million people worldwide are currently infected with HIV, the virus that causes AIDS, and about 2.3 million people become newly infected every year. HIV is mainly transmitted through unprotected sex with an infected partner. However, people who inject drugs (PWID) have a particularly high risk of HIV infection because blood transfer through needle and syringe sharing can transmit the virus. It is estimated that 5%–10% of all people living with HIV are PWID. Indeed, in some regions of the world the primary route of HIV transmission is through shared drug injection equipment and the prevalence (the proportion of a population that has a specific disease) of HIV infection among PWID is very high. In Asia, for example, more than a quarter of PWID are HIV positive. Because the high prevalence of HIV among PWID poses a global health challenge, bodies such as the Joint United Nations Programme on HIV/AIDS endorse harm reduction strategies to prevent risky injection behaviors among PWID. These strategies include the provision of clean needles and syringes, opioid substitution therapy such as methadone maintenance treatment, and antiretroviral treatment for HIV-positive PWID.
Why Was This Study Done?
Although harm reduction strategies for combating HIV epidemics among PWID have been implemented in several countries, few large-scale studies have examined the association between HIV incidence (the proportion of new cases of HIV in a population per year) and exposure to harm reduction programs among PWID. In this cohort study (an investigation that determines the characteristics of a group of people and then follows them over time), the researchers determine the association between harm reduction programs and HIV incidence among PWID in Taiwan. HIV infections used to be rare among the 60,000 PWID living in Taiwan, but after the introduction of a new HIV strain into the country in 2003, an HIV epidemic spread rapidly. In response, the Taiwanese government introduced a pilot program of harm reduction that included the provision of clean needles and syringes and health education in July 2005. The program was expanded to include methadone maintenance treatment in early 2006 and implemented nationwide in June 2006.
What Did the Researchers Do and Find?
The researchers enrolled two study populations. The first cohort comprised 3,851 PWID who were incarcerated for illicit drug use between 2004 and 2010 and who tested positive for HIV upon admission into prison. By using the BED assay, which indicates whether an HIV infection is recent, the researchers were able to determine the HIV incidence among the prisoners. In 2004, the estimated HIV incidence among prisoners with a history of drug injection was 6.44%. The incidence peaked in 2005 at 18.2%, but fell to 0.3% in 2010.
The second study population comprised 2,473 individuals who were HIV negative on January 1, 2006, and who had been incarcerated for drug use crimes but were released on July 16, 2007, during an amnesty. The researchers regularly interviewed these participants between their release and 2010 about their use of harm reduction interventions, and obtained other data about them (for example, diagnosis of HIV infection) from official databases. Analysis of all these data indicated that, in this cohort, attendance at methadone maintenance treatment clinics and frequent use of needle and syringe services were both associated with a significantly lower HIV incidence.
What Do These Findings Mean?
These findings suggest that the introduction of a comprehensive harm reduction program in Taiwan was associated with a significant reduction in the HIV incidence rate among PWID. These findings must be interpreted with caution, however. First, because the participants in the study were selected from PWID with histories of incarceration, the findings may not be representative of all PWID in Taiwan or of PWID in other countries. Second, PWID who chose to use needle and syringe services or methadone maintenance treatment clinics might have shared other unknown characteristics that affected their risk of HIV infection. Finally, some of the reduction in HIV incidence seen during the study is likely to be associated with the availability of free treatment, which has been offered to all HIV-positive individuals in Taiwan since 1997. Despite these limitations, these findings suggest that countries with a high prevalence and incidence of HIV among PWID should provide comprehensive harm reduction services to their populations to reduce risky drug injection behaviors.
Additional Information
Please access these websites via the online version of this summary at
Information is available from the US National Institute of Allergy and Infectious diseases on HIV infection and AIDS
NAM/aidsmap provides basic information about HIV/AIDS, and summaries of recent research findings on HIV care and treatment
Information is available from Avert, an international AIDS charity, on many aspects of HIV/AIDS, including information on injecting drug users and HIV/AIDS and on harm reduction and HIV prevention (in English and Spanish)
The US National Institute on Drug Abuse also provides information about drug abuse and HIV/AIDS (in English and Spanish)
The 2013 UNAIDS World AIDS Day report provides up-to-date information about the AIDS epidemic and efforts to halt it
Personal stories about living with HIV/AIDS are available through Avert, Nam/aidsmap, and Healthtalkonline
PMCID: PMC3979649  PMID: 24714449
21.  Solid pancreatic lesions: The choice of fine-needle aspiration-needle to optimize the diagnosis 
Endoscopic Ultrasound  2014;3(Suppl 1):S12-S13.
Endoscopic ultrasonography (EUS)-guided fine-needle aspiration (FNA) have a better accuracy for the detection of pancreatic tumors compared with others images modalities. We assessed if the image criteria of elastography and contrast harmonic echo-endoscopic ultrasound could help in choosing the appropriate FNA-needle in the evaluation of focal pancreatic mass in other to maximize the diagnostic yield. This study prospectively included all new patients with focal pancreatic masses referred to be examined by EUS from October to December/2013. A total of 21 patients performed EUS with sequentially elastography and intravenous injection of a second-generation contrast agent (2.4 mL of SonoVue, Braco International, The Netherlands). The lesions which appear hipovascular were assessed with 22 gauge or 25 gauge FNA-needles. The hipervascular masses were biopsied with 19 gauge needles.
The topography of the lesions varied on 13 at the head, 4 at the body and 1 on the tail. The finding of a hypoenhanced mass was found in 57% (12/21 patients). Hyperenhanced was detected in 28% (6/21 patients). There were 14% (three patients) which the data were not recorded. The cytological diagnosis was achieved in 81% (17/21 patients) on the first biopsy. The others four patients have reached the diagnosis on the second examination. Of those four patients, in one was used the ProCore 25 gauge (lesion on the uncinatus process), and another one was used both 22 gauge and 25 gauge in the first examination.
A characterization of the pancreatic lesions with elastography and contrast agents might be useful for clinical decision of which needle is better to improve biopsy quality and minimize EUS-FNA negatives results.
PMCID: PMC4569908  PMID: 26425510
22.  Recognition of and steps to mitigate anxiety and fear of pain in injectable diabetes treatment 
Injectable treatments, such as glucagon-like peptide-1 receptor agonists and insulin, are options for the pharmacologic treatment of type 2 diabetes. Numerous barriers lead to delay in initiating injectable treatment, which, in turn, may lead to inadequate glycemic control and increased risk of diabetes-related complications, underscoring the need to understand and address these barriers. Barriers to the initiation of injectable therapy, strategies to mitigate barriers, and information about needle attributes and their relation to needle pain are reviewed on the basis of published literature retrieval and our clinical experience. Barriers to the initiation of injectable therapy originate from both patients and practitioners. Anxiety about and fear of injection-associated pain has been estimated to affect approximately 30%–50% of patients before the initiation of diabetes education interventions. Advances in needle design have minimized the pain associated with injections, and recent data suggest that actual pain and bleeding associated with various needle gauges (21-gauge to 31-gauge) are mild. Other barriers include concerns about the ability to handle injectable therapy, concerns about treatment side effects, and impacts on quality of life. Practitioners can help to mitigate barriers to injectable treatment for type 2 diabetes by understanding patient perceptions, improving education, and setting realistic expectations about therapy. Strategies for minimizing injection-associated fear and anxiety include a combination of assessment, appropriate needle selection, patient education, behavioral interventions, and monitoring.
PMCID: PMC4303400  PMID: 25653546
type 2 diabetes; injection; needle; anxiety; fear
23.  A simple technique for fat biopsy of PBB-exposed individuals. 
A simple nonsurgical technique of obtaining fat samples by aspiration from the gluteal prominence was developed by Hirsh in 1960 and has been in use in our Nutrition Clinic at the Mount Sinai Hospital for several years. We have modified it for field use and the analysis of fat-soluble hydrocarbon residues. All the materials which will contain the fat sample to be analyzed are washed with acetone and pesticide residue-free hexane, and a 15 gauge needle and 33 cc syringe are sterilized. Aspiration of fat from the lateral gluteal prominence is accomplished under local xylocaine anesthetic. The anesthetic also serves as the vehicle into which the fat is broken by the shearing action of the 15 gauge needle. Fat particles are sucked into the syringe by a constant vacuum kept on the syringe during lateral movement of the needle under (and parallel to) the skin within the gluteal fat pad; 200--500 ml of fat can be obtained for hydrocarbon residue analysis. The only complications have been some mild hematomas at the site of the aspiration. The method avoids surgical biopsy and sutures and takes about 7--8 min.
PMCID: PMC1637465  PMID: 209973
24.  Impact of a Modified Needle Tip Geometry on Penetration Force as well as Acceptability, Preference, and Perceived Pain in Subjects with Diabetes 
Multiple factors impact subcutaneous insulin injection pain. Injection devices [e.g., syringe or pen needle (PN)] affect pain due to needle length, diameter, needle polishing and lubrication, and needle tip geometry.
We evaluated a modified 5-bevel PN tip in 32 G × 4 mm 31 G × 5 mm and 8 mm PNs vs the equivalent marketed 3-bevel PNs in laboratory penetration force testing, as well as in insulin-taking subjects for overall acceptability, comparative pain, and preference. The clinical tests were done in three ways: paired insertions with the subjects blinded to PN tip geometry, after brief at-home use of 5-bevel PNs, and again with subjects informed about each needle’s tip geometry in paired insertions.
Average penetration force in a skin substitute was 23% lower with the 5-bevel PNs vs similar 3-bevel PNs (p ≤ 0.01). In blinded testing and after at-home use, patients rated the 5-bevel needle as acceptable. After short-term home use, patients rated the 5-bevel PN less painful and preferable to their usual PN (both p < 0.01). In paired, informed testing, the 5-bevel PN was less painful and preferred to subjects’ currently used needles (p ≤ 0.01) and to other marketed PNs (p < 0.01).
Needle tip geometry affects penetration force. When blinded, patients did not distinguish differences in PN tip geometry with fine-gauge PN insertions. A 5-bevel needle tip is perceived as less painful and is preferred by subjects following home use for usual injections. Similar results occurred when patients were informed that they were using a needle with a modified tip.
PMCID: PMC3380774  PMID: 22538142
bevel; injection; needle tip; pain; pen needle
25.  Optimizing gene transfer to conventional outflow cells in living mouse eyes 
Experimental eye research  2013;109:8-16.
The mouse eye has physiological and genetic advantages to study conventional outflow function. However, its small size and shallow anterior chamber presents technical challenges to efficient intracameral delivery of genetic material to conventional outflow cells. The goal of this study was to optimize methods to overcome this technical hurdle, without damaging ocular structures or compromising outflow function. Gene targeting was monitored by immunofluorescence microscopy after transduction of adenovirus encoding green fluorescent protein driven by a CMV promoter. Guided by a micromanipulator and stereomicroscope, virus was delivered intracamerally to anesthetized mice by bolus injection using 33 gauge needle attached to Hamilton syringe or infusion with glass micropipette connected to syringe pump. The total number of particles introduced remained constant, while volume of injected virus solution (3–10 µl) was varied for each method and time of infusion (3–40 min) tested. Outflow facility and intraocular pressure were monitored invasively using established techniques. Unlike bolus injections or slow infusions, introduction of virus intracamerally during rapid infusions (3 min) at any volume tested preferentially targeted trabecular meshwork and Schlemm's canal cells, with minimal transduction of neighboring cells. While infusions resulted in transient intraocular pressure spikes (commensurate with volume infused, Δ40–70 mmHg), eyes typically recovered within 60 minutes. Transduced eyes displayed normal outflow facility and tissue morphology 3–6 days after infusions. Taken together, fast infusion of virus solution in small volumes intracamerally is a novel and effective method to selectively deliver agents to conventional outflow cells in living mice.
PMCID: PMC3615119  PMID: 23337742
Aqueous Humor; Glaucoma; Trabecular Meshwork; Schlemm’s Canal

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