Treatments are being developed for an increasing number of mucopolysaccharidoses, and early diagnosis is expected to be necessary to maximize the benefits of therapy. Therefore, we developed an assay for N-acetylgalactosamine-6-sulfate sulfatase (GALNS), the enzyme deficient in mucopolysaccharidosis IVA (Morquio A syndrome), that is applicable for clinical diagnosis.
A novel substrate for GALNS was synthesized for a new enzyme activity assay that is based on tandem mass spectrometry and uses dried blood spots (DBSs) as the enzyme source. We optimized the assay conditions, including the substrate concentration, reaction pH, lead formate concentration, incubation time, punch size of the DBS, and mass spectrometer conditions. We also assessed inter- and intraassay variation.
The assay uses either solid-phase or liquid-phase extraction before analysis by mass spectrometry. An evaluation of blood spots from 90 randomly chosen healthy newborns and 9 patients with Morquio A syndrome showed a well-defined interval between their respective enzyme activities. Inter- and intraassay imprecision was <10%.
This tandem mass spectrometry assay requires a minimal number of sample-preparation steps, thus making it easy to implement. The assay has the potential to be adopted for early diagnosis of Morquio A syndrome. We believe this assay could be performed in a multiplex fashion with assays for other lysosomal enzymes.
Rationale: Dry eye is the most prevalent condition seen by the ophthalmologist, in particular in elderly. The identification of new common risk factors (computer use and contact lens wear) extends the disease among the young people. The early diagnosis of dry eye is essential, but difficult, because the biochemical changes in tear film usually occur before any detectable signs. Due its advantages, electrophoresis of tear proteins could be an important tool for diagnosis of tear film impairment in high risk groups for dry eye.
Objective: The role of tear proteins electrophoresis in early diagnosis of dry eye related to computer use and contact lens wear, as well as the biochemical changes in these high risk groups are presented.
Methods: This review will summarize the actual data concerning the electrophoretic changes of tear proteins in computer users and contact lens wearers, two common high risk groups for dry eye.
Discussion: Electrophoresis of tear proteins using automated system Hyrys–Hydrasys SEBIA France is an important tool for early diagnosis of tear film alterations and monitoring of therapy. The quantification of many proteins in a single analysis using a small quantity of unconcentrated reflex tears is the main advantage of this technique. Electrophoresis of tear proteins should became a prerequisite, in particular for computer users less than 3h/day, as well as at prescribing contact lenses.
Abbreviations: DED– dry eye disease, EGF–epidermal growth factor, IL interleukins, MMP–metalloproteinase, ELISA– Enzyme–linked immunosorbent assay, SDS– sodium dodecyl sulfate, CVS– computer vision syndrome, CLRDE– contact lens– related dry eye
Dry eye; computer users; contact lens; electrophoresis; tear proteins
Background and Purpose. Dry needling is an effective therapy for the treatment of pain associated with myofascial trigger point (MTrP). However, the biochemical effects of dry needling that are associated with pain, inflammation, and hypoxia are unclear. This study investigated the activities of β-endorphin, substance P, TNF-α, COX-2, HIF-1α, iNOS, and VEGF after different dosages of dry needling at the myofascial trigger spots (MTrSs) of a skeletal muscle in rabbit. Materials and Methods. Dry needling was performed either with one dosage (1D) or five dosages (5D) into the biceps femoris with MTrSs in New Zealand rabbits. Biceps femoris, serum, and dorsal root ganglion (DRG) were sampled immediately and 5 d after dry needling for β-endorphin, substance P, TNF-α, COX-2, HIF-1α, iNOS, and VEGF immunoassays. Results. The 1D treatment enhanced the β-endorphin levels in the biceps femoris and serum and reduced substance P in the biceps femoris and DRG. The 5D treatment reversed these effects and was accompanied by increase of TNF-α, COX-2, HIF-1α, iNOS, and VEGF production in the biceps femoris. Moreover, the higher levels of these biochemicals were still maintained 5 d after treatment. Conclusion. Dry needling at the MTrSs modulates various biochemicals associated with pain, inflammation, and hypoxia in a dose-dependent manner.
To determine the feasibility of sending dried blood spots (DBS) to an overseas processing center for the diagnosis of HIV infection in infants in rural Haiti.
The program took place in the Central Department of Haiti. Children under 18 months of age who were born to an HIV-infected mother or who had a positive HIV antibody test had blood collected on filter paper. Once dry, specimens were labeled with a unique identifying number, placed in sealed gas-impermeable envelopes containing a desiccant, stored at room temperature, and mailed to a commercial laboratory in The Netherlands, where blood was eluted from the filter paper and analyzed by the Retina™ rainbow HIV-1 RNA assay. Infants were tested at 1 month of age and again at 4 months of age.
The DBS protocol was easily scaled up. During the study period, 138 infants had HIV status confirmed; 15 of them were found to be HIV infected and were enrolled in appropriate HIV care, and 123 were confirmed to be HIV uninfected, avoiding unnecessary prophylactic antibiotics and providing reassurance to caregivers.
Central, overseas processing of DBS is a feasible solution for the timely diagnosis of HIV infection in infants where local capacity is unavailable. Regional processing centers for DBS could improve the access of millions of children in Latin America and the Caribbean to timely diagnosis of HIV infection.
Blood specimen collection; HIV serodiagnosis; poverty areas; Haiti
In industrialised nations age-related macular degeneration (AMD) is the most common cause of blindness and severe visual impairment. AMD is a disease of the retina characterized by the accumulation of metabolic products in the macula. In early stages drusen and pigment disorders occur, in late stages a dry form is distinguished from the exsudative form with choroidal neovascularisation. AMD causes vision disorders such as blurred vision of the central part of the visual field, leading finally to a dark spot. Several therapies are available for the exsudative form, however an exact diagnosis is partially essential. The gold standard for the diagnosis of AMD is fluorescein angiography (FA), an invasive investigation with intravenous application of a dye. Optical coherence tomography (OCT) is a more recent non-invasive procedure.
The aim of this HTA report is to investigate the efficacy and efficiency of OCT compared to FA. Ethical, societal and legal aspects are also considered.
A systematic literature search was performed in 34 international databases which yielded 2324 articles. Eight publications were included for assessment, according to predefined selection criteria.
The number of studies investigating OCT compared to FA in patients with AMD is presently very limited and the quality of the studies is generally low. The number of investigated patients is below 35 in four publications and in only one publication it is above 100. Moreover in most of the articles very selected patient groups are studied. Economic studies concerning the efficiency of OCT compared to FA cannot be identified.
Even though the patient groups investigated and the objectives of the studies are very heterogenous, all publications uniformly show that OCT cannot replace FA. However, OCT yields additional diagnostic findings and may verify unclear findings of FA. Therefore the application of OCT in addition to FA is useful in many cases. With regard to costs German patients on average currently have to pay more for performing OCT than for performing FA.
Future studies have to show whether OCT may give diagnostic information essential for therapeutic decisions in addition to FA and whether it can replace FA in selected cases. The number of patients included in these studies should be high enough to answer relevant questions with sufficient statistical power. An economic model calculation can be built upon the resulting findings.
Making a diagnosis of HIV infection in children aged less than 18 months remains a challenge in low resource settings like Zambia due to the limited availability of gold standard testing with HIV DNA PCR. Clinicians in rural areas have to depend on clinical diagnosis to start HAART as they wait for the dry blood spot (DBS) for DNA PCR results sent from the urban centers.
This descriptive cross-sectional study was performed at the University Teaching Hospital, Lusaka, Zambia. 299 HIV-exposed children aged less than 18 months were enrolled following a consent procedure. Patients were evaluated for HIV infection based on the World Health Organization’s presumptive diagnostic criteria (WHO-PDC), integrated management of childhood illnesses (IMCI) criteria, select physical exam abnormalities, and CD4% and findings were compared with HIV-DNA PCR results.
Of the 299 exposed patients analyzed, 111(37%) were found to be HIV-positive by DNA PCR. The median CD4% in the infected children was 18%. WHO-PDC used on its own had 23% sensitivity (95% CI 17–32%) and 93% specificity (88–96%), respectively, whereas IMCI criterion had 10% sensitivity (6–17%) and 97% specificity (94–99%), respectively. Multivariate analysis was used to identify the most sensitive predictors when combined with the WHO-PDC and IMCI criterion. WHO-PDC with CD4% improved the sensitivity to 77% (68–83%) with a specificity of 83% (77–88%), positive predictive value (PPV) of 73% (64–80%) and negative predictive value (NPV) of 86% (80–90%). IMCI with CD4% improved sensitivity to 80% (71–87%) with a specificity of 88% (82–92%), PPV 78% (69–85%) and NPV 89% (84–93%). The addition of individual physical exam findings without CD4% improved the sensitivity of WHO-PDC only modestly. When the WHO-PDC, weight<3rd percentile, hepatomegaly, splenomegaly, lymphadenopathy and CD4% were combined, the sensitivity improved to 85% (77–90%), specificity 63% (56–70%), PPV 58% (50–65%) and NPV of 88% (81–92%).
The WHO-PDC clinical algorithm can be improved when combined with a CD4% <25% in children less than 12 months of age and CD4% <20% in those between 12 and 18 months.
HIV; early infant diagnosis; diagnosis; Zambia
Blood spots collected onto filter paper are an established and convenient source of antibodies for serological diagnosis and epidemiological surveys. Although recommendations for the storage and analysis of small molecule analytes in blood spots exist, there are no published systematic studies of the stability of antibodies under different storage conditions.
Blood spots, on filter paper or glass fibre mats and containing malaria-endemic plasma, were desiccated and stored at various temperatures for different times. Eluates of these spots were assayed for antibodies against two Plasmodium falciparum antigens, MSP-119 and MSP2, and calculated titres used to fit an exponential (first order kinetic) decay model. The first order rate constants (k) for each spot storage temperature were used to fit an Arrhenius equation, in order to estimate the thermal and temporal stability of antibodies in dried blood spots. The utility of blood spots for serological assays was confirmed by comparing antibodies eluted from blood spots with the equivalent plasma values in a series of samples from North Eastern Tanzania and by using blood spot-derived antibodies to estimate malaria transmission intensity in this site and for two localities in Uganda.
Antibodies in spots on filter paper and glass fibre paper had similar stabilities but blood was more easily absorbed onto filter papers than glass fibre, spots were more regular and spot size was more closely correlated with blood volume for filter paper spots. Desiccated spots could be stored at or below 4°C for extended periods, but were stable for only very limited periods at ambient temperature. When desiccated, recoveries of antibodies that are predominantly of IgG1 or IgG3 subclasses were similar. Recoveries of antibodies from paired samples of serum and of blood spots from Tanzania which had been suitably stored showed similar recoveries of antibodies, but spots which had been stored for extended periods at ambient humidity and temperature showed severe loss of recoveries. Estimates of malaria transmission intensity obtained from serum and from blood spots were similar, and values obtained using blood spots agreed well with entomologically determined values.
This study has demonstrated the suitability of filter paper blood spots paper for collection of serum antibodies, and provided clear guidelines for the treatment and storage of filter papers which emphasize the importance of desiccation and minimisation of time spent at ambient temperatures. A recommended protocol for collecting, storing and assaying blood spots is provided.
Interferon-gamma release assays (IGRAs) have provided a new method for the diagnosis of Mycobacterium tuberculosis infection. However, the role of IGRAs for the diagnosis of active tuberculosis (TB), especially in HIV-infected patients remains unclear.
We searched PubMed, EMBASE and Cochrane databases to identify studies published in January 2001–July 2011 that evaluated the evidence of using QuantiFERON-TB Gold in-tube (QFT-GIT) and T-SPOT.TB (T-SPOT) on blood for the diagnosis of active TB in HIV-infected patients.
The search identified 16 eligible studies that included 2801 HIV-infected individuals (637 culture confirmed TB cases). The pooled sensitivity for the diagnosis of active TB was 76.7% (95%CI, 71.6–80.5%) and 77.4% (95%CI, 71.4–82.6%) for QFT-GIT and T-SPOT, respectively, while the specificity was 76.1% (95%CI, 74.0–78.0%) and 63.1% (95%CI, 57.6–68.3%) after excluding the indeterminate results. Studies conducted in low/middle income countries showed slightly lower sensitivity and specificity when compared to that in high-income countries. The proportion of indeterminate results was as high as 10% (95%CI, 8.8–11.3%) and 13.2% (95%CI, 10.6–16.0%) for QFT-GIT and T-SPOT, respectively.
IGRAs in their current formulations have limited accuracy in diagnosing active TB in HIV-infected patients, and should not be used alone to rule out or rule in active TB cases in HIV-infected patients. Further modification is needed to improve their accuracy.
The World Health Organization (WHO) recommends same day sputum microscopy (spot-spot) in preference to conventional strategy (spot-morning) for the diagnosis of smear positive tuberculosis with the view that completing diagnosis on a single day may be more convenient to the patients and reduce pre-treatment losses to follow-up.
We conducted a cross-sectional study in seven selected district level hospitals of Chhattisgarh State, India. During October 2012 – March 2013, two sputum specimens (spot-early morning) were collected from consecutively enrolled adult (≥18 years) presumptive TB patients as per current national guidelines. In addition, a second sample was collected (one hour after the collection of first spot sample) from the same patients. All the samples were examined by ziehl-Neelsen (ZN) microscopy. McNemar’s test was used to compare statistical differences in the proportion smear positive between the two approaches (spot-spot versus spot-morning).
Of 2551 presumptive TB patients, 69% were male. All patients provided the first spot specimen, 2361 (93%) provided the second spot specimen, and 2435 (96%) provided an early morning specimen. 72% of specimens were mucopurulent in conventional strategy as compared to 60% in same day strategy. The proportion of smear-positive patients diagnosed by same day microscopy was 14%, as compared to 17% by the conventional method (p<0.001). A total of 73 (16.9%) potential cases were missed by the same day method compared to only 2 (0.5%) by the conventional method.
Same-day microscopy method missed 17% of smear-positive cases and contrary to prior perception, did not increase the proportion of suspects providing the second sample. These findings call for an urgent need to revisit the WHO recommendation of switching to same-day diagnosis over the current policy.
Diagnosis of HIV infection in infants is difficult due to the presence of maternal antibodies; only nucleic acid assays are very helpful in early detection. Filter papers are especially useful for blood collection in resource-poor settings with limited access to diagnostic facilities.
Materials & Methods:
DBS samples were collected from the infants born to HIV seropositive mothers who had received single dose nevirapine at onset of labor. The samples were directly spotted onto the Whatman 903 cards from heel, big toe or finger prick depending on the age of the infants. A total of 766 infant samples were collected on dried blood spots (DBS) and transported to the Department of Experimental Medicine (DEM), Chennai, for testing from different government hospitals of rural and urban parts of Tamil Nadu, South India. According to National AIDS Control Organization's (NACO) protocol DNA was extracted from all these DBS and PCR was performed using the Roche kit version 1.5.
Fifteen infants were found to be HIV positive and 751 were HIV negative; all these 15 positive infants and 49 negative infants who were in the age group between 10 and 18 months were repeated with another DBS and compared with whole blood. The DBS results were concordant with the whole blood method and the sensitivity and specificity were 100%.
Dried blood spots; HIV; Polymerase chain reaction
Rapid and cost-effective methods for HIV-1 diagnosis and viral load monitoring would greatly enhance the clinical management of HIV-1 infected adults and children in limited-resource settings. Recent recommendations to treat perinatally infected infants within the first year of life are feasible only if early diagnosis is routinely available. Dried blood spots (DBS) on filter paper are an easy and convenient way to collect and transport blood samples. A rapid and cost effective method to diagnose and quantify HIV-1 from DBS is urgently needed to facilitate early diagnosis of HIV-1 infection and monitoring of antiretroviral therapy.
Methods and Findings
We have developed a real-time LightCycler (rtLC) PCR assay to detect and quantify HIV-1 from DBS. HIV-1 RNA extracted from DBS was amplified in a one-step, single-tube system using primers specific for long-terminal repeat sequences that are conserved across all HIV-1 clades. SYBR Green dye was used to quantify PCR amplicons and HIV-1 RNA copy numbers were determined from a standard curve generated using serially diluted known copies of HIV-1 RNA. This assay detected samples across clades, has a dynamic range of 5 log10, and %CV <8% up to 4 log10 dilution. Plasma HIV-1 RNA copy numbers obtained using this method correlated well with the Roche Ultrasensitive (r = 0.91) and branched DNA (r = 0.89) assays. The lower limit of detection (95%) was estimated to be 136 copies. The rtLC DBS assay was 2.5 fold rapid as well as 40-fold cheaper when compared to commercial assays. Adaptation of the assay into other real-time systems demonstrated similar performance.
The accuracy, reliability, genotype inclusivity and affordability, along with the small volumes of blood required for the assay suggest that the rtLC DBS assay will be useful for early diagnosis and monitoring of pediatric HIV-1 infection in resource-limited settings.
Blood samples collected in epidemiological and clinical investigations and then stored, often at room temperature, as blood spots dried on a filter paper have become one of the most popular source of material for further molecular analyses of malaria parasites. The dried blood spots are often archived so that they can be used for further retrospective investigations of parasite prevalence, or as new genetic markers come to the fore. However, the suitability of the template obtained from dried blood spots that have been stored for long periods for DNA amplification is not known.
DNA from 267 archived blood spots collected over a period of 12 years from persons with microscopically confirmed Plasmodium falciparum infection was purified by one of two methods, Chelex and Qiagen columns. These templates were subjected to highly sensitive nested PCR amplification targeting three parasite loci that differ in length and/or copy number.
When a 1.6 kb fragment of the parasites’ small subunit ribosomal RNA was targeted (primary amplification), the efficiency of P. falciparum detection decreased in samples archived for more than six years, reaching very low levels for those stored for more than 10 years. Positive amplification was generally obtained more often with Qiagen-extracted templates. P. falciparum could be detected in 32 of the 40 negative Qiagen-extracted templates when a microsatellite of about 180 bp was targeted. The remaining eight samples gave a positive amplification when a small region of 238 bp of the higher copy number (20 to 200) mitochondrial genome was targeted.
The average length of DNA fragments that can be recovered from dried blood spots decreases with storage time. Recovery of the DNA is somewhat improved, especially in older samples, by the use of a commercial DNA purification column, but targets larger than 1.5 kb are unlikely to be present 10 years after the initial blood collection, when the average length of the DNA fragments present is likely to be around a few hundred bp. In conclusion, the utility of archived dried blood spots for molecular analyses decreases with storage time.
Archival blood spots; Plasmodium falciparum; Polymerase chain reaction
Treatments now available for Mucopolysaccharidosis I require early detection for optimum therapy. Therefore, we have developed an assay appropriate for newborn screening of the activity of the relevant enzyme, α-l-iduronidase.
We synthesized a new α-l-iduronidase substrate that can be used to assay the enzyme by use of tandem mass spectrometry together with an internal standard. The assay uses a dried blood spot on a newborn screening card as the enzyme source. The assay protocol uses a simple liquid-liquid extraction step prior to mass spectrometry. We optimized enzyme reaction conditions and procedures for the assay, including the concentration of substrate, the reaction pH, the incubation time, and mass spectrometer operation. We also assessed inter- and intra-assay imprecision.
When the assay was tested on dried blood spots, the α-l-iduronidase activity measured for 5 patients with Mucopolysaccharidosis I was well below the interval found for 10 randomly chosen newborns. Inter- and intra-assay imprecision were less than 10 %. The synthesis of the α-l-iduronidase substrate is practical on a scale needed to support newborn screening demands.
This newly developed tandem mass spectrometry assay has the potential to be adopted for newborn screening of Mucopolysaccharidosis I. It presents advantages compared to the one previously published from this laboratory and has the potential to be performed in a multiplex fashion with several lysosomal enzymes relevant to treatable lysosomal storage diseases.
Since the 1960s newborn screening (NBS) for several rare and serious disorders has been in place across Australia. Testing of a simple blood spot now enables the early detection of over 30 conditions. Policies across Australian states have diverged in some aspects of NBS, especially in the retention and further use of dried blood spots collected as part of the screening and attempts are underway to bring some further national consistency. Whilst this has initiated debate amongst health professionals and policy makers there is limited empirical evidence of wider community attitudes to such issues.
This research has explored the range and depth of views held by the wider community in New South Wales through moderated small group discussions. It has also assessed the range and depth of responses where the groups are reconvened after being given further information.
The findings suggest that there is limited community awareness of the public health importance of NBS and especially that resulting biological samples are stored. Members of the wider community presented with opportunities to consider current procedures and policies appear reassured and to have high levels of trust. However there are clearly some groups who have concerns with the storage of dried blood spot specimens and perceive that these may be abused.
Policy implications and conclusion
The findings will inform health professionals and policy makers as to the perceived benefits and future challenges NBS raises for the wider community. The findings have implications for improving current communications about NBS, maintaining public confidence and the development of state and national initiatives in genetic health.
The quality of MALDI Imaging analyses crucially depends on the matrix application protocols. Unfortunately, the currently used protocols have significant disadvantages that impair the robust and routine use of tissue imaging as analytical or even diagnostic approach. While pneumatic spray preparations provide high surface homogeneity and spatial resolution of the images, the process is manual and highly irreproducible. Depending of the degree of tissue wetting either the analyte molecules are badly incorporated into the matrix (too dry) or the spatial resolution is lost (too wet). Nano-spotting on the other hand provides quality spectra but as a sequential process it is slow, spatial resolution is limited by the spot raster (typical >100 μm) and perfect alignment with the mass spectrometer is critical.
We introduce an entirely new approach that combines the advantages of above methods and eliminates the disadvantages. In the new preparation device, matrix aerosol (< 50 μm droplets) is created by vibrational vaporization under controlled conditions that is gently deposited onto tissue sections. The entire microscope slide with multiple sections can be matrix coated in one setup. An optical sensor allows to monitor and to control all relevant preparation parameters at real-time: deposition periods, intervals, matrix layer thickness, wetness, drying rate, etc. This QC process built into the preparation process provides highly reproducible preparations over several slides and at different days. No user intervention is required in the fully automated process.
On tissue it was possible to achieve lateral resolutions down to 50 μm.
A method has been tested in laboratory mice to monitor for the presence of brevetoxins in blood after exposure. The use of blood collection cards is an adaptation of a method employed for routine diagnostic and genetic testing of newborns. Blood is collected and applied to a 0.5-inch diameter circle on a specially prepared blood collection card and allowed to dry. The blood spots are then extracted and the presence of toxin activity is first screened using a high throughput receptor binding assay. Positive samples are then examined for specific brevetoxin congeners by liquid chromatography-tandem mass spectrometry. Preliminary experiments tested the efficiency and linearity of toxin extraction from blood spiked with brevetoxin-3 (PbTx-3). Blood from treated mice was tested for the presence of brevetoxin at different times following exposure to a sublethal dose (180 microg/kg PbTx-3). Brevetoxin activity determined by receptor assay increased to 25 +/- 7.4 nM PbTx-3 equivalents within 4 hr after exposure and was still detectable in three of four animals 24 hr after exposure. Tandem mass spectrometry provided confirmation of PbTx-3, which also increased for the time points between 0.5 and 4.0 hr exposure. However, PbTx-3 was not detected at 24 hr, which suggested the formation of a biologically active metabolite. We anticipate that this approach will provide a method to biomonitor brevetoxins in living marine resources (e.g., finfish), protected species, and humans.
Pakistan is experiencing a growing HIV epidemic. Antiretroviral drugs (ARV) have been smuggled into the country and available without prescription since the early 1990s, but are now provided free of cost by the government. We assessed the prevalence of HIV-1, drug resistance, and subtype distributions. Blood specimens were collected from HIV-1-infected participants registered in Sindh Province on dry blood spot (DBS) cards in 2008. Pol, protease, and partial reverse transcriptase regions were sequenced after reverse transcriptase PCR (RT-PCR). HIV-1 subtype was assigned by phylogenetic analysis. Primary drug resistance was analyzed by the Calibrated Population Resistance (CPR) tool using the Stanford Surveillance Drug Resistance Mutation (SDRM) major mutation list. Out of 100 blood samples collected, 42 were suitable for testing. Out of 42, 11 were ARV-receiving and 31 ARV-naive patients. Among them, 24 were injection drug users (IDUs), four immigrants, two hijras (male transvestites), two men who have sex with men (MSM), four prisoners, one female sex workers, two spouses of HIV-infected persons, and four from the general population. ARV resistance among naive patients was 2/31 (6.5%) and 36.4% (4/11) among ARV-experienced patients making an overall resistance of 14.2%. HIV-1 subtype A1 was the predominant subtype found in 35/42 (83.3%) followed by CRF35_AD and C, 6.5% each. Subtype D and G were found in one (2.4%) each. A significant proportion of Pakistani HIV patients has ARV drug resistance. Physicians treating patients should consider the magnitude of drug resistance while selecting regimens, and address drug adherence aggressively.
Cernik, A. A., and Sayers, M. H. P. (1971).Brit. J. industr. Med.,28, 392-398. Determination of lead in capillary blood using a paper punched disc atomic absorption technique. Application to the supervision of lead workers. The presence of lead in blood is the most incontrovertible evidence of absorption but hitherto the need for venepuncture has limited its determination in the supervision of industrial workers. Micro-methods using atomic absorption spectrophotometry (AAS) have, however, made possible the development of a sufficiently reliable test using a drop of blood obtainable by ear prick for use in the field for screening purposes.
A micro-sampling method by AAS is compared with a routine polarographic procedure (POL) using venous blood (corr. coeff. = 0·990). The pipetting of microlitres of blood can be eliminated by spotting the blood onto filter paper, allowing it to dry in air, and then using a punched-out standard disc of dried blood for analysis instead. Correlation of this method (PD) with the micro-sampling technique (AAS) is good (r=0·981).
The PD method using capillary blood also correlates acceptably with the micromethod using venous blood (r = 0·913). A pilot field study using capillary blood estimated by the PD technique showed that with this method blood can be collected by ear prick in factories for monitoring workers in the lead industry, thus eliminating the need for routine venepuncture.
Hemoglobinopathies are the most common inherited disorders. Newborn blood screening for clinically significant hemoglobin variants, including sickle (HbS), HbC, and HbD, has been adopted in many countries as it is widely acknowledged that early detection improves the outcome. We present a method for determination of Hb variants by direct surface sampling of dried blood spots by use of an Advion Triversa Nanomate automated electrospray system coupled to a high-resolution mass spectrometer. The method involves no sample preparation. It is possible to unambiguously identify homozygous and heterozygous HbS, HbC, and HbD variants in <10 min without the need for additional confirmation. The method allows for repeated analysis of a single blood spot over a prolonged time period and is tolerant of blood spot storage conditions.
To assess technical and operational performance of a dried blood spot (DBS)-based HIV-1 RNA service for remote healthcare facilities in a low-income country.
A method comparison and operational evaluation of DBS RNA against conventional tests for early infant diagnosis of HIV and HIV RNA quantitation under field conditions in Tanzania.
DBS were prepared and plasma was frozen at −80°C. DBS were mailed and plasma couriered to a central laboratory for testing using the Abbott m2000 system. Infant diagnosis DBS were also tested for HIV-1 DNA by ROCHE COBAS AmpliPrep/COBAS TaqMan System. Results of DBS RNA were compared with conventional tests; program performance was described.
Among 176 infant diagnosis participants, using a threshold of ≥1,000 copies/mL, sensitivity and specificity of DBS versus plasma RNA were 1.00 and 0.99, and of DBS RNA versus DBS DNA were 0.97 and 1.00. Among 137 viral load monitoring participants, when plasma and DBS RNA were compared R was 0.9709; R was 0.9675 ≥5,000 copies/mL but was 0.7301 <5,000 copies/mL. The highest plasma RNA value at which DBS RNA was not detected was 2,084 copies/mL. Median (range) turnaround time from sample collection to result receipt at sites was 23 (4–69) days. The Tanzania mail service successfully transmitted all DBS and results between sites and the central laboratory.
Under program conditions in Tanzania, DBS provided HIV-1 RNA results comparable to conventional methods to remote healthcare facilities. DBS RNA testing is an alternative to liquid plasma for HIV-1 RNA services in remote areas.
Tanzania; HIV; diagnosis; laboratory techniques and procedures; reverse transcriptase polymerase chain reaction; blood specimen collection
In Tanzania, less than a third of HIV infected children estimated to be in need of antiretroviral therapy (ART) are receiving it. In this setting where other infections and malnutrition mimic signs and symptoms of AIDS, early diagnosis of HIV among HIV-exposed infants without specialized virologic testing can be a complex process. We aimed to introduce an Early Infant Diagnosis (EID) pilot program using HIV DNA Polymerase Chain Reaction (PCR) testing with the intent of making EID nationally available based on lessons learned in the first 6 months of implementation.
In September 2006, a molecular biology laboratory at Bugando Medical Center was established in order to perform HIV DNA PCR testing using Dried Blood Spots (DBS). Ninety- six health workers from 4 health facilities were trained in the identification and care of HIV-exposed infants, HIV testing algorithms and collection of DBS samples. Paper-based tracking systems for monitoring the program that fed into a simple electronic database were introduced at the sites and in the laboratory. Time from birth to first HIV DNA PCR testing and to receipt of test results were assessed using Kaplan-Meier curves.
From October 2006 to March 2007, 510 HIV-exposed infants were identified from the 4 health facilities. Of these, 441(87%) infants had an HIV DNA PCR test at a median age of 4 months (IQR 1 to 8 months) and 75(17%) were PCR positive. Parents/guardians for a total of 242(55%) HIV-exposed infants returned to receive PCR test results, including 51/75 (68%) of those PCR positive, 187/361 (52%) of the PCR negative, and 4/5 (80%) of those with indeterminate PCR results. The median time between blood draw for PCR testing and receipt of test results by the parent or guardian was 5 weeks (range <1 week to 14 weeks) among children who tested PCR positive and 10 weeks (range <1 week to 21 weeks) for those that tested PCR negative.
The EID pilot program successfully introduced systems for identification of HIV-exposed infants. There was a high response as hundreds of HIV-exposed infants were registered and tested in a 6 month period. Challenges included the large proportion of parents not returning for PCR test results. Experience from the pilot phase has informed the national roll-out of the EID program currently underway in Tanzania.
The World Health Organization (WHO) recommends collection of two sputum samples for tuberculosis (TB) diagnosis, with at least one being an early morning (EM) using smear microscopy. It remains unclear whether this is necessary even when sputum culture is employed. Here, we determined the diagnostic yield from spot and the incremental yield from the EM sputum sample cultures among TB-suspected adolescents from rural Uganda.
Sputum samples (both spot and early-morning) from 1862 adolescents were cultured by the Lowenstein-Jensen (LJ) and Mycobacterium Growth Indicator Tube (MGIT) methods. For spot samples, the diagnostic yields for TB were 19.0% and 57.1% with LJ and MGIT, respectively, whereas the incremental yields (not totals) of the early-morning sample were 9.5% and 42.9% (P < 0.001) with LJ and MGIT, respectively. Among TB-suspected adolescents in rural Uganda, the EM sputum culture has a high incremental diagnostic yield. Therefore, EM sputum in addition to spot sample culture is necessary for improved TB case detection.
One of the key limitations for proteomic studies using 2-dimensional gel electrophoresis (2DE) is the lack of rapid, robust and reproducible methods for detecting, matching and quantifying protein spots. The most commonly used approaches involve first detecting spots and drawing spot boundaries on individual gels, then matching spots across gels and finally quantifying each spot by calculating normalized spot volumes. This approach is time consuming, error-prone and frequently requires extensive manual editing, which can unintentionally introduce bias into the results.
We introduce a new method for spot detection and quantification called Pinnacle that is automatic, quick, sensitive and specific and yields spot quantifications that are reliable and precise. This method incorporates a spot definition that is based on simple, straightforward criteria rather than complex arbitrary definitions, and results in no missing data. Using dilution series for validation, we demonstrate Pinnacle outperformed two well-established 2DE analysis packages, proving to be more accurate and yielding smaller coefficiant of variations (CVs). More accurate quantifications may lead to increased power for detecting differentially expressed spots, an idea supported by the results of our group comparison experiment. Our fast, automatic analysis method makes it feasible to conduct very large 2DE-based proteomic studies that are adequately powered to find important protein expression differences.
Two protocols for the extraction of cytomegalovirus (CMV) DNA and two methods for the amplification of CMV DNA in dried blood spots were evaluated for the retrospective diagnosis of congenital CMV infection. During the period from 1996 to 2006, a urine screening program detected 76 congenitally infected neonates. Stored Guthrie cards with blood from 55 cases and 12 controls were tested. Two spots of dried blood were cut from each card and evaluated in two centers. CMV DNA was extracted from a whole single spot. Center 1 used phenol-chloroform extraction and ethanol precipitation followed by a conventional PCR. Center 2 used the NucliSens easyMAG automated DNA/RNA extraction platform (bioMérieux) followed by a real-time PCR. For evaluation of the extraction method, DNA extracted from each blood spot was evaluated by the amplification method used by the collaborating center. The sensitivities were 66% for center 1 and 73% for center 2. None of the controls were positive. A sensitivity as high as 82% could be obtained by combining the most sensitive extraction method (the phenol-chloroform procedure) with the most sensitive PCR method (real-time PCR). The detection rate was not influenced by the duration of storage of the spots. The sensitivity was higher with blood from congenitally infected cases due to a primary maternal CMV infection, regardless of the protocol used. However, the difference reached significance only for the least-sensitive protocol (P = 0.036).
Deficiency of ornithine-δ-aminotransferase (OAT) in humans results in gyrate atrophy. Early diagnosis may allow initiation of treatment before irreversible damage has occurred. However, diagnosis is commonly delayed well into adulthood because of the nonspecific character of initial symptoms. Here, we report findings in a neonate who was evaluated because of a positive family history of OAT deficiency. The reversed enzymatic flux in early infancy resulted in borderline low ornithine concentration – evoking urea cycle disturbances – and increased proline. In addition, plasma citrulline was low. Consequently, the proline/citrulline ratio in plasma was increased compared to controls. To find out whether amino acid profiling in neonatal dried blood spots is suitable to detect OAT deficiency, we evaluated the original newborn dried blood spots of two affected patients and compared it with a database of >450,000 newborns tested in Minnesota since 2004. Proline concentrations (777 and 1,381 μmol/L) were above the 99 percentile (776 μmol/L) of the general population, and citrulline concentrations (4.5 and 4.9 μmol/L) only just above the 1 percentile (4.37 μmol/L). The proline/citrulline ratio was 172.9 and 281.8, respectively. This ratio was calculated retrospectively in the normal population, and the 99 percentile was 97.6. Applying this ratio for NBS could lead to early and specific detection of neonatal OAT deficiency, with no additional expense to newborn screening laboratories quantifying amino acids. Given that early diagnosis of OAT disease can lead to earlier treatment and prevent visual impairment, further studies are indicated to evaluate whether newborn screening for OAT deficiency is warranted.