Application of ATP assay for in vitro drug screening testing against human derived M. leprae

In this study, the ATP content of M. leprae exposed to various antimicrobial agents has been measured to evaluate its usefulness in drug sensitivity screening. Purified M. leprae suspensions from human biopsies have been incubated at 30 degrees C in a modified Dubos medium in the presence of different concentrations of various drugs viz., Rifampicin, Ethionamide, Ethambutol, Cycloserine, Dapsone, Clofazimine, Erythromycin and Tetracycline. ATP levels were estimated at 0, 7 days, 14 days of incubation by the procedures modified and standardised at this laboratory. ATP decay was accelerated by ethionamide, rifampicin, clofazimine, dapsone, erythromycin and to a lesser extent by cycloserine, whereas ethambutol and tetracycline did not have any significant effect. The rate of decay depended on the concentrations of these drugs. ATP assay promises to be a useful system for in vitro drug sensitivity screening against M. leprae isolated from patients.     

Full-thickness human skin explants for testing the toxicity of topically applied chemicals

This report describes a model organ-culture system for testing the toxicity of chemical substances that are topically applied to human skin. In this system, the viable keratinocytes in the full-thickness skin explants are protected by the same keratinized layer as skin remaining on the donor, and toxicity can be assessed microscopically and/or biochemically. The human skin specimens were discards from a variety of surgical procedures. They were cut into full-thickness 1.0-cm2 explants, and briefly exposed to the military vesicant sulfur mustard (SM), which was used as a model toxicant. The explants were then organ cultured in small Petri dishes for 24 h at 36 degrees C. In the 0.03-1.0% dosage range, a straight-line dose-response relationship occurred between the concentration of SM applied and the number of paranuclear vacuoles seen histologically in the epidermis. Within the same SM dosage range, there was also a proportional decrease in 14C-leucine incorporation by the explants. Thus, the number of paranuclear vacuoles reflected decreases in protein synthesis by the injured epidermal cells. The epidermis of full-thickness untreated (control) human skin explants usually remained viable for 7 d when stored at 4 degrees C in culture medium. During storage, a relatively small number of paranuclear vacuoles developed within the epidermis, but the explants were still quite satisfactory for testing SM toxicity. Incubation (for 4 or 24 h at 36 degrees C) of such control skin explants reduced (often by 50%) the small number of paranuclear vacuoles produced during 4-7 d of storage. This reduction was probably caused by autolysis of many of the vacuolated cells. Two types of paranuclear vacuoles could be identified by both light and electron microscopy: a storage type and a toxicant type. The storage type seemed to be caused by autolysis of cell components. The toxicant type seemed to be caused by an invagination of the plasma membrane. Only toxicant-type vacuoles increased appreciably in number when skin explants were exposed to mustard, and to other toxicants.     

采用葡萄糖消耗法快速测定念珠菌对唑类药物的敏感性

目的:探讨采用葡萄糖消耗法进行快速念珠菌药敏试验的实用性和优越性。方法:采用葡萄糖消耗法快速检测104株念珠菌对氟康唑和伊曲康唑的敏感性,并和NCCLS M27-A方案微量法进行比较。受试菌株主要分离自临床深部真菌感染的患者,包括白念珠菌(C. albicans)45株、近平滑念珠菌(C. parapsilosis)24株、热带念珠菌(C.tropicalis)17株、克柔念珠菌(C.krusei)10株、光滑念珠菌(C. glabrata)8株。结果:对于氟康唑,两种方法在±1个、±2个稀释度范围内的一致性为76.0％和89.4％;对于伊曲康唑,两种方法的一致性分别为82.7％和89.4％。结论:葡萄糖消耗法和NCCLS M27-A方案微量法的一致性较高,可以用于念珠菌药敏的快速测定。     

Evaluation of contact sensitivity of rubber chemicals using the murine local lymph node assay

The sensitizing abilities of 4 rubber additives, tetramelhylthiuram disulfide (TMTD), 2-mercaplob-enzothiazole (MBT), V-isopropyl-N'-phenyl-p-phenylenediamine (IPPD) and zinc diethyldithiocar-bamate (ZDEC), were evaluated using the murine local lymph node assay. Exposure to IPPD induced a significant increase of lymph node cell proliferation in the draining lymph nodes even at a low concentration. Exposure to TMTD and MBT induced moderate proliferation responses, while ZDEC induced a weak proliferation even at the higher concentrations. The sensitizing potency of each chemical was described in terms of the concentration that increased lymph node cell proliferation by a factor of 2 over that in the vehicle-treated control group. The concentrations of IPPD, TMTD. MBT and ZDEC were 0.14%. 10%, respectively.     

Skin equivalent assay: An optimized method for testing for hair growth reconstitution capacity of epidermal and dermal cells

Hair follicle reconstitution requires highly organized epithelial‐mesenchymal interactions. Skin equivalents containing the epidermal and dermal cells with hair reconstitution capacity can reproduce these processes, but have not been established. This study was conducted to develop a hair follicle‐producing three‐dimensional (3D) skin equivalent assay using neonate mouse epidermal and dermal cells. A skin equivalent comprised of mouse dermal cells (MDCs) embedded in type I collagen and overlaid with mouse epidermal cells (MECs) was used. MDCs were mixed with type I collagen and cultured for 7 days. One day after adding MECs on top, the composites were grafted onto nude mice. MDCs cultured on a two‐dimensional (2D) plate for 7 days and mixed with MECs as a negative control, and freshly isolated MDCs and MECs mixture (chamber assay) as a positive control were also grafted. Six weeks after grafting, regenerated hair follicles were analysed. Our 3D skin equivalent culture assay reproducibly regenerated hair follicles, while MDCs precultured in the 2D model with MECs did not. Compared to the chamber assay, which produced randomly oriented hair follicles, nearly all regenerated hair follicles in our assay extruded through the skin and numerous regenerated hair follicles were higher than those in the chamber assay. Several representative genes associated with hair induction showed higher expression in our assay than in the 2D model. When Wnt3a was added, the number of regenerated hairs increased. Organized hair follicle regeneration was accomplished using our assay. This approach can be applied to assess a test agent with hair growth‐promoting effects.     

Identification of causative chemicals of allergic contact dermatitis using a combination of patch testing in patients and chemical analysis

3 cases of allergic contact dermatitis from industrial rubber products were investigated using a combination of patch testing in patients and chemical analysis of causative rubber products by gas chromatography (GC), GC-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC). Our studies revealed N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), a typical rubber allergen, as a causative chemical in a case from a brand of heavy-duty rubber gloves and a case from a black rubber ring for car manufacture, and zinc ethylphenyldithiocarbamate (ZEPC), a dithiocarbamate (DTC)-type accelerator, as a causative chemical in a case from a brand of rubber work gloves: both IPPD and ZEPC, which showed positive patch test reactions, were confirmed in the extracts of the causative rubber products by GC, GC-MS and/or HPLC.     

Herpes simplex virus type 2 (HSV-2) Western blot confirmatory testing among men testing positive for HSV-2 using the focus enzyme-linked immunosorbent assay in a sexually transmitted disease clinic

OBJECTIVE: The objective of this study was to define the positive predictive value (PPV) of the Focus herpes simplex virus type 2 (HSV-2) enzyme-linked immunosorbent assay (ELISA) in a low HSV-2 prevalence population and to develop a new test interpretation algorithm. METHODS: HSV-2 Western blots were performed on sera from male sexually transmitted disease clinic patients testing HSV-2 ELISA-positive and used to define a new class of indeterminate HSV-2 ELISA result. HSV-2 Western blots were then prospectively performed on sequential sera with indeterminate HSV-2 ELISAs. RESULTS: Ninety-one (84%) of 108 HSV-2 ELISA-positive sera tested HSV-2 Western blot-positive. Western blot positivity was more common in men without herpes simplex virus type 1 (HSV-1) antibody than in those with HSV-1 antibody (93% vs 76%, P = 0.02) and in men with a history or clinical evidence of genital lesions (88% vs 80%, P = 0.30). Selectively raising the ELISA index value defining HSV-2 positivity from >1.1 to >or=3.0 either among HSV-1-positive men or among those without a history or clinical evidence of genital lesions increased the PPV to >or=93%. Prospective evaluation of an algorithm incorporating HSV-1 serostatus found that 11 of 70 persons with indeterminate HSV-2 ELISAs were Western blot-positive. CONCLUSIONS: Clinicians should consider selectively using a higher index value to define Focus ELISA HSV-2 positivity based on either HSV-1 serostatus or clinical circumstances.     

Potential Role of Cytosolic RNA Sensor MDA5 as an Inhibitor for Keratinocyte Differentiation in the Pathogenesis of Psoriasis

BackgroundPsoriasis is a chronic inflammatory skin disease. The etiology of psoriasis is not fully understood, but the genetic background is considered to be the most important factor. To date, many psoriasis-related genes have been discovered, but the role of many important genes has not been well understood.ObjectiveThe purpose of this study is to uncover possible roles of MDA5 in psoriasis.MethodsExpression of MDA5 was investigated using immunohistochemistry. Then, MDA5 was overexpressed in keratinocytes using a recombinant adenovirus.ResultsAs a result of immunohistochemical staining, the expression of MDA5 was significantly increased in the epidermis of psoriasis compared to normal skin. Similarly, the expression of MDA5 was increased in imiquimod-induced psoriasiform dermatitis model. In cultured keratinocytes, toll-like receptor 3 agonist poly(I:C) induced expression of MDA5 at both mRNA and protein levels. When MDA5 was overexpressed using a recombinant adenovirus, poly(I:C)-induced cytokine expression was significantly increased. Finally, MDA5 overexpression significantly inhibited calcium-induced differentiation of keratinocytes.ConclusionThese results suggest that MDA5 increases in psoriasis and negatively regulates keratinocyte differentiation.     

Identification of causative chemicals of allergic contact dermatitis using a combination of patch testing in patients and chemical analysis Application to cases from rubber gloves

5 cases of allergic contact dermatitis from rubber gloves were investigated by our recommended procedures using a combination of patch testing in patients and chemical analysis of causative rubber products by gas chromatography (GC) and high-performance liquid chromatography (HPLC). We previously confirmed that zinc ethylphenyldithiocarbamate (ZEPC), a dithiocarbamae-type accelerator (DTC), was causative in a case of allergic contact dermatitis from rubber work gloves. Subsequently, we have clarified that DTCs such as zinc dimethyldithiocarbamate (ZDMC), zinc diethyldithiocarbamate (ZDEC) and zinc dibutyldithiocarbamate (ZDBC) and amines such as dimethylamine (DMA), diethylamine (DEA) and piperidine (PIP) were also causative in cases from surgical rubber gloves. Thus, our investigative studies revealed that, although thiurams have been taken much more notice of as allergenic compounds than their corresponding DTCs and amines, not only DTCs such as ZDMC, ZDEC, ZDBC and ZEPC, but also amines such as DMA, DEA and PIP were noteworthy causative candidates of allergic contact dermatitis from rubber gloves.