Allergen extracts from the house dust mite (HDM, Dermatophagoides pteronyssinus) are widely utilized for diagnosis and treatment of allergic diseases. It is known that allergen extracts degrade and lose potency when stored over time.
This study aimed to determine the optimal conditions for stability of allergen extracts. This study was undertaken to investigate the optimal storage conditions for HDM extracts, the effects of adding 0.03% human serum albumin (HSA) and 50% glycerol were evaluated at -20℃, 4℃, and room temperature (RT). Changes in protein and group 1 major allergen (Der p 1) concentration, as well as allergenicity were measured over a 1 year period using the Bradford assay, two-site ELISA, and ELISA inhibition.
Protein concentrations decreased by 86%, 51%, and 6% at RT, 4℃, and -20℃, respectively, when stored in distilled water. Overall allergenicity remained high (89.9%) when the extracts was reconstituted in 50% glycerol solution, and was 93.1% when reconstituted in 50% glycerol and 0.03% HSA at RT. Allergenicity was decreased to 36.6% and 33.3%, however, reconstitution in DW or 0.03% HSA solution at RT, respectively. Allergenicity was remained high as 92.0%-97.0% when stored at 4℃ regardless of the buffer conditions.
Storage temperature is the most important factor in preserving allergenicity of HDM extracts, which is ideal at 4℃. The addition of 50% glycerol to the storage buffer was also found to play an important role in increasing the shelf-life of HDM extracts at RT.
Allergen; house dust mite; stability
To evaluate the usefulness of ultrasonography as a follow-up tool for evaluating the effects of complex decongestive physiotherapy (CDPT) in breast cancer-related lymphedema (BCRL).
Twenty patients with BCRL were enrolled in this study. All patients had undergone therapy in the CDPT program for 2 weeks. Soft tissue thickness of both the affected and unaffected upper limb was measured before and after CDPT. The measurements were taken at 3 points (the mid-point between the medial and lateral epicondyles at the elbow level, 10 cm proximal and 10 cm distal to the elbow) with and without pressure. We then calculated the compliance of soft tissue before and after CDPT. Circumferences of both the affected and unaffected upper limb were also measured before and after CDPT at the 3 defined points.
After 2 weeks of the CDPT program, the circumference and soft tissue thickness of the unaffected upper limb did not significantly change. In the affected upper limb, the circumference was significantly reduced in the 3 point, when compared with measurements taken prior to treatment. Additionally, soft tissue thickness was significantly reduced at the elbow and 10 cm proximal to the elbow. After CDPT, compliance at each of the 3 points had increased, but this trend was not significantly different.
Our results showed that arm circumference and ultrasonography-derived soft tissue thickness was useful as a way of assessing therapeutic effects of CDPT.
Lymphedema; Ultrasonography; Complex decongestive physiotherapy
The progressive restriction of cell fate during lineage differentiation is a poorly understood phenomenon despite its ubiquity in multicellular organisms. We recently used a cell fusion assay to define a mode of epigenetic silencing that we termed “occlusion”, wherein affected genes are silenced by cis-acting chromatin mechanisms irrespective of whether trans-acting transcriptional activators are present. We hypothesized that occlusion of lineage-inappropriate genes could contribute to cell fate restriction. Here, we test this hypothesis by introducing bacterial artificial chromosomes (BACs), which are devoid of chromatin modifications necessary for occlusion, into mouse fibroblasts. We found that BAC transgenes corresponding to occluded endogenous genes are expressed in most cases, whereas BAC transgenes corresponding to silent but non-occluded endogenous genes are not expressed. This indicates that the cellular milieu in trans supports the expression of most occluded genes in fibroblasts, and that the silent state of these genes is solely the consequence of occlusion in cis. For the BAC corresponding to the occluded myogenic master regulator Myf5, expression of the Myf5 transgene on the BAC triggered fibroblasts to acquire a muscle-like phenotype. These results provide compelling evidence for a critical role of gene occlusion in cell fate restriction.
cell fate restriction; occlusion; bacterial artificial chromosome
The cockroach (CR) is an important cause of respiratory allergic disorders. We prepared a German CR extract in a standardized way and analyzed its allergenic properties.
The extract was prepared from German CR (Blattella germanica) obtained from a Korean colony, and its allergenic activity was compared with that of the commercial Hollister-Stier (HS) extract. The concentrations of Bla g 1 and Bla g 2 were measured, and an in vitro specific IgE binding inhibition assay was performed to assess IgE reactivity. Proteolytic activity was examined by gelatin zymography.
Bla g 1 and Bla g 2 were detected at 405 U/mg and 273 ng/mg, respectively, in the Korean extract, and at 187 U/mg and 56 ng/mg, respectively, in the HS extract. The Korean extract showed 94.2% inhibition of IgE reactivity, as compared with the HS extract. A similar pattern of IgE-reactive bands was detected for the two extracts, indicating that their allergenic components are similar. The proteolytic activities of the Korean and HS extracts were found to be similar in gelatin zymography. The endotoxin levels in the Korean and HS extracts were 3,440 EU/mL and 6,580 EU/mL, respectively.
The German CR extract was prepared in a standardized way. The extract produced in this study will be useful for the development of allergy diagnostics and immunotherapeutic agents.
Allergen; German cockroach; Korea; standardization
We experienced a case of immunoglobulin E (IgE) mediated anaphylaxis to levodropropizine. The patient was an 18-year old Korean woman. After taking the common cold medication including acetaminophen, domperidone, and levodropropizine, skin rash, angioedema and anaphylaxis were developed immediately. As she was tolerable to acetaminophen alone, we thought the culprit agent was maybe a levodropropizine tablet. To confirm the culprit, she underwent skin prick test and oral drug provocation test with the suspected one. Finally we detected levodropropizine specific IgE and confirmed the specificity by inhibition enzyme-linked immunosorbent assay (ELISA).
Levodropropizine; anaphylaxis; drug hypersensitivity
Spontaneous reporting systems have several weak points, such as low reporting rates and insufficient clinical information. Active surveillance programs, such as ward rounds and a clinical data repository (CDR), may supplement the weak points of such systems. We developed active surveillance programs and compared them with existing spontaneous reporting.
We collected adverse drug event (ADE) cases, which comprised 1,055 cases of spontaneous reporting, 309 reported by ward rounds, and 229 found using a CDR. The clinical features and causative drugs were evaluated.
Active surveillance programs detected additional serious ADEs compared to those of spontaneous reporting programs. The ADEs identified by CDR (22.9%) were more likely to be classified as "serious" than those reported spontaneously (5.2%) or identified during ward rounds (10.3%). Causative drugs also differed. Opioids, antibiotics, and contrast media were the most common drugs causing ADEs in the spontaneous reporting system, whereas the active surveillance programs identified antibiotics as the most common causative drug. Clinical features also differed. ADEs with gastrointestinal manifestations were reported most frequently by spontaneous reporting programs. ADEs reported from active surveillance more reliably identified events associated with changes in laboratory values, such as hepatobiliary toxicity, hematologic manifestations, and nephrologic manifestations, compared with spontaneous reporting programs.
Our findings suggest that active surveillance programs can supplement spontaneous reporting systems in hospitals. ADEs related to laboratory abnormalities were monitored more closely by active surveillance programs and may be useful for identification of serious ADEs.
Drug toxicity; Spontaneous reporting; Active surveillance
The progressive restriction of cell fate during lineage differentiation is a poorly understood phenomenon despite its ubiquity in multicellular organisms. We recently used a cell fusion assay to define a mode of epigenetic silencing that we termed “occlusion”, wherein affected genes are silenced by cis-acting chromatin mechanisms irrespective of whether trans-acting transcriptional activators are present. We hypothesized that occlusion of lineage-inappropriate genes could contribute to cell fate restriction. Here, we test this hypothesis by introducing bacterial artificial chromosomes (BACs) – which are devoid of chromatin modifications necessary for occlusion – into mouse fibroblasts. We found that BAC transgenes corresponding to occluded endogenous genes are expressed in most cases, whereas BAC transgenes corresponding to silent but non-occluded endogenous genes are not expressed. This indicates that the cellular milieu in trans supports the expression of most occluded genes in fibroblasts, and that the silent state of these genes is solely the consequence of occlusion in cis. For the BAC corresponding to the occluded myogenic master regulator Myf5, expression of the Myf5 transgene on the BAC triggered fibroblasts to acquire a muscle-like phenotype. These results provide compelling evidence for a critical role of gene occlusion in cell fate restriction.
cell fate restriction; occlusion; bacterial artificial chromosome
House dust mites are the most important cause of respiratory allergy in Korea. Standardization of allergen extracts is essential for improving diagnostics and immunotherapeutics. This study was undertaken to evaluate the allergenicity of standardized house dust mite allergen extracts from Korean house dust mite isolates.
Allergen extracts were prepared from cultured Korean house dust mites (Dermatophagoides farinae and D. pteronyssinus). Allergenic activities of Korean house dust mite extracts were compared to standardized extracts from a company in the United States whose allergen concentrations were expressed as Allergy Units (AUs). Specifically, we compared group 1 and 2 major allergens using two-site enzyme-linked immunosorbent assay (ELISA) kits and an in vivo intradermal test.
Major allergen concentrations were 17.0 µg/mg (5.0 µg/mg of Der f 1 and 12.0 µg/mg of Der f 2) for a D. farinae extract and 24.0 µg/mg (11.6 µg/mg of Der p 1 and 12.4 µg/mg of Der p 2) for a D. pteronyssinus extract. Using chloramphenicol (CAP) inhibition assays, AUs were 12.5 AU/µg for a D. farinae extract and 12.8 AU/µg for a D. pteronyssinus extract. Allergenic activities were 3- to 4-fold stronger when assessed by intradermal skin tests for in vivo standardization.
Allergen extracts were prepared from Korean house dust mites and the allergenicities of the extracts were estimated using AU measurements. House dust mite extracts prepared in this study could be utilized as a reference material, which will be useful for the development of diagnostic and immunotherapeutic reagents in Korea.
Allergen; house dust mite; standardization
The activity of the serine protease in the German cockroach allergen is important to the development of allergic disease. The protease-activated receptor (PAR)-2, which is expressed in numerous cell types in lung tissue, is known to mediate the cellular events caused by inhaled serine protease. Alveolar macrophages express PAR-2 and produce considerable amounts of tumor necrosis factor (TNF)-α. We determined whether the serine protease in German cockroach extract (GCE) enhances TNF-α production by alveolar macrophages through the PAR-2 pathway and whether the TNF-α production affects GCE-induced pulmonary inflammation. Effects of GCE on alveolar macrophages and TNF-α production were evaluated using in vitro MH-S and RAW264.6 cells and in vivo GCE-induced asthma models of BALB/c mice. GCE contained a large amount of serine protease. In the MH-S and RAW264.7 cells, GCE activated PAR-2 and thereby produced TNF-α. In the GCE-induced asthma model, intranasal administration of GCE increased airway hyperresponsiveness (AHR), inflammatory cell infiltration, productions of serum immunoglobulin E, interleukin (IL)-5, IL-13 and TNF-α production in alveolar macrophages. Blockade of serine proteases prevented the development of GCE induced allergic pathologies. TNF-α blockade also prevented the development of such asthma-like lesions. Depletion of alveolar macrophages reduced AHR and intracellular TNF-α level in pulmonary cell populations in the GCE-induced asthma model. These results suggest that serine protease from GCE affects asthma through an alveolar macrophage and TNF-α dependent manner, reflecting the close relation of innate and adaptive immune response in allergic asthma model.
Pharmacovigilance Research Network built a spontaneous reporting system and collected adverse drug reactions (ADRs) by electronic submission (e-sub) in Korea. We analyzed ADRs spontaneously reported through e-sub from regional health professionals.
Materials and Methods
Nine hundred and thirty three ADR cases were collected and analyzed from January to December in 2008. "A matter" was defined as one symptom matched to one culprit drug included in an ADR case. We collected and analyzed e-sub ADR cases and matters to determine common culprits and organ specified ADR matters.
There were 3,049 matters in 933 ADR cases for 1 year, and 3.3 matters per case were reported. In organ specific ADR classification, skin reactions which took the first place in 866 matters (28%) included urticaria and rash. The next cases were neurologic symptom (624 matters, 21%) and gastrointestinal symptom (581 matters, 19%). Doctor (53%) and pharmacist (31%) were the most important participants in e-sub spontaneous reporting system, and 3% of ADR cases were reported by patients or their guardians. WHO-Uppsala Monitoring Center causality assessment results showed certain 10.6%, probable 37.7%, possible 41.7% and below unlikely 10.0%. Culprit drugs were antibiotics (23.4%), neurologic agents (14.7%) and non-steroidal anti-inflammatory drugs (9.4%).
In our study, antibiotic was most common culprit drug, and skin manifestation was most common symptom in e-sub ADRs collected from regional healthcare practitioners in Korea.
Adverse drug reaction; spontaneous reporting; internet electronic submission; regional primary practice
Cockroach (CR) is an important inhalant allergen and can induce allergic asthma. However, the mechanism by which CR induces airway allergic inflammation and the role of endotoxin in CR extract are not clearly understood in regards to the development of airway inflammation. In this study, we evaluated whether endotoxin is essential to the development of CR induced airway allergic inflammation in mice.
Materials and Methods
Airway allergic inflammation was induced by intranasal administration of either CR extract, CR with additional endotoxin, or endotoxin depleted CR extract, respectively, in BALB/c wild type mice. CR induced inflammation was also evaluated with toll like receptor-4 (TLR-4) mutant (C3H/HeJ) and wild type (C3H/HeN) mice.
Intranasal administration of CR extracts significantly induced airway hyperresponsiveness (AHR), eosinophilic and neutrophilic airway inflammation, as well as goblet cell hyperplasia in a dose-dependent manner. The addition of endotoxin along with CR allergen attenuated eosinophilic inflammation, interleukin (IL)-13 level, and goblet cell hyperplasia of respiratory epithelium; however, it did not affect the development of AHR. Endotoxin depletion in CR extract did not attenuate eosinophilic inflammation and lymphocytosis in BAL fluid, AHR and IL-13 expression in the lungs compared to CR alone. The attenuation of AHR, eosinophilic inflammation, and goblet cell hyperplasia induced by CR extract alone was not different between TLR-4 mutant and the wild type mice. In addition, heat inactivated CR extract administration induced attenuated AHR and eosinophilic inflammation.
Endotoxin in CR extracts may not be essential to the development of airway inflammation.
Cockroach; endotoxin; toll like receptor-4
Hepatic adverse drug reactions (ADRs) to certain drugs may differ within each country, reflecting different patterns of prescription, socioeconomic status, and culture. The purpose of this study was to assess the suspected cause of hepatic ADRs using the spontaneously reported pharmacovigilance data from Korea. A total of 9,360 spontaneously reported adverse drug events (ADEs) from nine Pharmacovigilance Centers were analyzed. Risk of hepatic ADEs was assessed by calculating the reporting odds ratio (ROR). Of the 9,360 cases, 567 hepatic ADEs were reported. The most frequently prescribed drug classes inducing hepatic ADEs were anti-tuberculotics, cephalosporins, valproic acids, penicillins, quinolones, non-steroidal anti-inflammatory drugs (NSAIDs), anti-viral agents, and statins. ROR values were especially high in anti-tuberculosis drugs, systemic antifungal drugs for systemic use, anti-epileptics, propylthiouracil, and herbal medicines. Underlying diseases such as tuberculosis (6.9% vs 0.9%), pneumonia (4.9% vs 1.7%), intracranial injury including skull fracture (4.5% vs 0.9%), HIV (3.4% vs 0.4%), subarachnoid hemorrhage (2.8% vs 0.5%), and osteoporosis (2.4% vs 1.4%) were significantly more common in hepatic ADE group. In conclusion, anti-infective drugs, anti-epileptics, NSAIDs and statins are the most common suspects of the spontaneously reported hepatic ADEs, in Korea. Careful monitoring for such reactions is needed for the prescription of these drugs.
Drug-Induced Hepatitis; Etiology; Spontaneous Pharmacovigilance
Achieving high accuracy in the imaging of biological targets is a challenging issue. For MRI, to enhance imaging accuracy, two different imaging modes with specific contrast agents are used; one is T1 type for a “positive” MRI signal and the other is T2 type for a “negative” signal. Conventional contrast agents response only in a single imaging mode and frequently encounter ambiguities in the MR images. Here, we propose a “magnetically decoupled” core-shell design concept to develop a dual mode nanoparticle contrast agent (DMCA). This DMCA not only possesses superior MR contrast effects, but also has the unique capability of displaying “AND” logic signals in both the T1 and T2 modes. The latter enables self-confirmation of images and leads to a greater diagnostic accuracy. A variety of novel DMCAs are possible and the use of DMCAs can potentially bring the accuracy of MR imaging of diseases to a higher level.
Surgery for thoracic disc herniations is still challenging, and the disc excision via a posterior laminectomy is considered risky. A variety of dorsolateral and ventral approaches have been developed. However, the lateral extracavitary and transthoracic approach require extensive surgical exposure. Therefore, we adopted a posterior transdural approach for direct visualization without entry into the thoracic cavity. Three cases that illustrate this procedure are reported here with the preoperative findings, radiological findings and surgical techniques used. After the laminectomy, at the involved level, the dorsal dura was opened with a longitudinal paramedian incision. The cerebrospinal fluid was drained to gain more operating space. After sectioning of the dentate ligaments, gentle retraction was applied to the spinal cord. Between the rootlets above and below, the ventral dural bulging was clearly observed. A small paramedian dural incision was made over the disc space and the protruded disc fragment was removed. Neurological symptoms were improved, and no surgery-related complication was encountered. The posterior transdural approach may offer an alternative surgical option for selected patients with thoracic paracentral soft discs, while limiting the morbidity associated with the exposure.
Disc herniation; Transdural approach; Thoracic
Although the vertebral artery injuries (VAI) associated with cervical spine trauma are usually clinically occult, they may cause fatal ischemic damage to the brain stem and cerebellum.
We performed a prospective study using computed tomographic angiography (CTA) to determine the frequency of VAI associated with cervical spine injuries and investigate the clinical and radiological characteristics. Between January 2005 and August 2007, 99 consecutive patients with cervical spine fractures and/or dislocations were prospectively evaluated for patency of the VA, using the CTA, at the time of injury.
Complete disruption of blood flow through the VA was demonstrated in seven patients with unilateral occlusion (7.1%). There were four men and three women with a mean age of 43 (range, 33-55 years). Unilateral occlusion of the right vertebral artery occurred in four patients and of the left in three. Regarding the cervical injury type, two cases were cervical burst fractures (C6 and C7), two had C4-5 fracture/dislocations, two had a unilateral transverse foraminal fracture, and one had dens type III fracture. All patients presented with good patency of the contralateral VA. None of the patients developed secondary neurological deterioration due to vertebrobasilar ischemia during the follow-up period with a mean duration of 23 months.
VAI should be suspected in patients with cervical trauma that have cervical spine fractures and/or dislocations or transverse foramen fractures. CTA was useful as a rapid diagnostic method for ruling out VAI after cervical spine trauma.
Cervical spine; computed tomographic angiography; injury; vertebral artery
The effects of air cleaners on the removal of airborne indoor allergens, especially house dust mites (HDM), are still controversial. The objective of this study is to evaluate the effect of an air cleaner with an electrostatic filter on the removal of airborne mite allergens.
Materials and Methods
A dried HDM culture medium that contained mite body particles and excretions was dispersed in a chamber equipped with an electrostatic air cleaner. The number of airborne particles was recorded continuously by a dust spectrometer for 60 minutes. Airborne particles in the chamber were collected on a sampling filter at a flow rate of 10 L/min and the Der f 1 concentration in the filter extracts was measured by two-site ELISA.
The air cleaner efficiently removed airborne HDM particles. The air cleaner removed airborne HDM particles (size 2-12.5 µm) 11.4 ± 2.9 fold (cleaner operating for 15 minutes), 5.4 ± 0.7 fold (cleaner operating for 30 minutes), and 2.4 ± 0.2 fold (cleaner operating for 60 minutes) more than the removal of HDM particles by natural settle down. Removal kinetics differed according to the particle size of the airborne particles. The air cleaner decreased the concentration of Der f 1 in the extraction of airborne particles collected on the air sampling filter by 60.3%.
The electrostatic air cleaner can remove airborne HDM allergens and may be useful as a supplementary environmental control tool for HDM sensitized respiratory allergic patients.
House dust mite; electrostatic air cleaner; environmental control
Disc herniations at the L1-L2 and L2-L3 levels are different from those at lower levels of the lumbar spine with regard to clinical characteristics and surgical outcome. Spinal canals are narrower than those of lower levels, which may compromise multiple spinal nerve roots or conus medullaris. The aim of this study was to evaluate the clinical features and surgical outcomes of upper lumbar disc herniations.
We retrospectively reviewed the clinical features of 41 patients who had undergone surgery for single disc herniations at the L1-L2 and L2-3 levels from 1998 to 2007. The affected levels were L1-L2 in 14 patients and L2-L3 in 27 patients. Presenting symptoms and signs, patient characteristics, radiologic findings, operative methods, and surgical outcomes were investigated.
The mean age of patients with upper lumbar disc was 55.5 years (ranged 31 to 78). The mean follow-up period was 16.6 months. Most patients complained of back and buttock pain (38 patients, 92%), and radiating pain in areas such as the anterior or anterolateral aspect of the thigh (32 patients, 78%). Weakness of lower extremities was observed in 16 patients (39%) and sensory disturbance was presented in 19 patients (46%). Only 6 patients (14%) had undergone previous lumbar disc surgery. Discectomy was performed using three methods : unilateral laminectomy in 27 cases, bilateral laminectomy in 3 cases, and the transdural approach in 11 cases, which were performed through total laminectomy in 10 cases and unilateral laminectomy in 1 case. With regard to surgical outcomes, preoperative symptoms improved significantly in 33 patients (80.5%), partially in 7 patients (17%), and were aggravated in 1 patient (2.5%).
Clinical features of disc herniations at the L1-L2 and L2-L3 levels were variable, and localized sensory change or pain was rarely demonstrated. In most cases, the discectomy was performed successfully by conventional posterior laminectomy. On the other hand, in large central broad based disc herniation, when the neural elements are severely compromised, the posterior transdural approach could be an alternative.
Clinical feature; Disc herniation; Transdural; Upper lumbar
Ossification of the ligamentum flavum (OLF) is a rare cause of thoracic myelopathy. The aim of this study was to identify factors associated with the surgical outcome on the basis of preoperative clinical and radiological findings.
Data obtained in 26 patients whot underwent posterior decompression for thoracic myelopathy, caused by thoracic OLF, were analyzed retrospectively. Patient age, duration of symptoms, OLF type, preoperative and postoperative neurological status using the Japanese Orthopedic Association (JOA) scoring system, surgical outcome, and other factors were reviewed. We compared the various factors and postoperative prognosis. All patients had undergone decompressive laminectomy and excision of the OLF.
Using the JOA score, the functional improvement was excellent in 8 patients, good in 14, fair in 2, and unchanged in 2. A mean preoperative JOA score of 6.65 improved to 8.17 after an average of 27.3 months. According to our analysis, age, gender, duration of symptoms, the involved spinal level, coexisting spinal disorders, associated trauma, intramedullary signal change, and dural adhesions were not related to the surgical outcome. However, the preoperative JOA score and type of OLF were the most important predictors of the surgical outcome.
Early diagnosis and sufficient surgical decompression could improve the functional prognosis for thoracic OLF. The postoperative results were found to be significantly associated with the preoperative severity of myelopathy and type of OLF.
Ossification of ligamentum flavum; Thoracic myelopathy; Surgical outcome
We recently described two opposing states of transcriptional competency. One is termed ‘competent’ whereby a gene is capable of responding to trans-acting transcription factors of the cell, such that it is active if appropriate transcriptional activators are present, though it can also be silent if activators are absent or repressors are present. The other is termed ‘occluded’ whereby a gene is silenced by cis-acting, chromatin-based mechanisms in a manner that blocks it from responding to trans-acting factors, such that it is silent even when activators are present in the cellular milieu. We proposed that gene occlusion is a mechanism by which differentiated cells stably maintain their phenotypic identities. Here, we describe chromatin analysis of occluded genes. We found that DNA methylation plays a causal role in maintaining occlusion for a subset of occluded genes. We further examined a variety of other chromatin marks typically associated with transcriptional silencing, including histone variants, covalent histone modifications and chromatin-associated proteins. Surprisingly, we found that although many of these marks are robustly linked to silent genes (which include both occluded genes and genes that are competent but silent), none is linked specifically to occluded genes. Although the observation does not rule out a possible causal role of these chromatin marks in occlusion, it does suggest that these marks might be secondary effect rather than primary cause of the silent state in many genes.
A gene’s transcriptional output is the combined product of two inputs: diffusible factors in the cellular milieu acting in trans, and chromatin state acting in cis. Here, we describe a strategy for dissecting the relative contribution of cis versus trans mechanisms to gene regulation. Referred to as trans complementation, it entails fusing two disparate cell types and searching for genes differentially expressed between the two genomes of fused cells. Any differential expression can be causally attributed to cis mechanisms because the two genomes of fused cells share a single homogenized milieu in trans. This assay uncovered a state of transcriptional competency that we termed ‘occluded’ whereby affected genes are silenced by cis-acting mechanisms in a manner that blocks them from responding to the trans-acting milieu of the cell. Importantly, occluded genes in a given cell type tend to include master triggers of alternative cell fates. Furthermore, the occluded state is maintained during cell division and is extraordinarily stable under a wide range of physiological conditions. These results support the model that the occlusion of lineage-inappropriate genes is a key mechanism of cell fate restriction. The identification of occluded genes by our assay provides a hitherto unavailable functional readout of chromatin state that is distinct from and complementary to gene expression status.
Vivax malaria was endemic on the Korean peninsula for many centuries until the late 1970's when the Republic of Korea (ROK) was declared "malaria free". Since its re-emergence in 1993, the number of malaria cases in the military increased exponentially through 2000 near the demilitarized zone. Chemoprophylaxis with chloroquine and primaquine has been used in the ROK Army since 1997 in an attempt to reduce the number of the malaria cases throughout the ROK. Data show that chemoprophylaxis contributed, in part, to the decrease in the number of malaria cases among military personnel. However, mass chemoprophylaxis on a large scale in the ROK Army is unprecedented and extensive supervision and monitoring is warranted to determine its effectiveness and to monitor the appearance of chloroquine tolerant/resistant strains of Plasmodium vivax.
Malaria; Malaria, Vivax; Korea; Chemoprevention; Chloroquine; Primaquine