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Biomedical subjects

R Kalish

Publications and source records attributed to R Kalish.

At least 19 recordsLinked to original sources

Quantization of 2D hole gas in conductive hydrogenated diamond surfaces observed by electron field emission.

Discrete jumps are observed in the emitted current density (J) versus extraction electric field (E) curves in electron field emission measurements from a conductive, hydrogen-terminated air-exposed diamond surface. These jumps are well reproduced by computations based on the assumption that a 2D nanoscale quantum system with discrete energy levels exists in the diamond near-surface layer. The present results confirm the formation of well-defined quantum states of holes in the 2D surface layer present on hydrogenated air-exposed diamond surfaces.

Journal Article↗

A preliminary dosimetric characterization of chemical vapor deposition diamond detector prototypes in photon and electron radiotherapy beams.

Three radiation detectors based on polycrystalline diamond films with different thickness and resistivity, obtained by microwave chemical vapor deposition, were tested to assess their suitability for relative dosimetry of photon and electron beams supplied by clinical linear accelerators. All samples showed a linear response as a function of the absorbed dose. The sensitivity per unit of detector sensitive volume spanned between 7 and 43 nC Gy(-1) mm(-3) with an applied electric field of 40 kV/cm. The dose rate dependence was evaluated following the Fowler theory and delta coefficient values between 0.95 and 1.00 were found for the three samples when polarized at 40 kV/cm. Percentage depth dose curves, output factors, and normalized dose profiles were determined for 6 and 10 MV photon beams and for 6 and 15 MeV electron beams. The results obtained with the diamond detectors were in good agreement with those obtained by reference detector measurements [all the data were within the experimental uncertainty of 1% (1sigma)].

Crystallization↗

Frequency analysis of autoreactive T-helper 1 and 2 cells in bullous pemphigoid and pemphigus vulgaris by enzyme-linked immunospot assay.

BACKGROUND: Bullous pemphigoid (BP) and pemphigus vulgaris (PV) are autoimmune bullous skin diseases mediated by autoantibodies against adhesion molecules of the skin. Previous studies have identified autoreactive T cells in patients with BP and PV, which may be critical in providing B-cell help for autoantibody production. OBJECTIVES: To evaluate the frequency of autoreactive T-helper (Th) 1 and Th2 cells in patients with BP (n = 7) or PV (n = 1) and in healthy controls (n = 11). METHODS: In an enzyme-linked immunospot (ELISPOT) assay, microtitre plates were coated with antihuman interleukin (IL)-5 IgG or antihuman interferon (IFN)-gamma IgG prior to culturing human peripheral blood lymphocytes (PBL) with BP180 or desmoglein (Dsg) 3 proteins for 7 days. Cytokine-producing autoreactive T cells were visualized as spot-forming units. RESULTS: One BP patient with extensive blisters had 5.1 +/- 1.5 (mean +/- SD) BP180-reactive Th1 cells and 2.9 +/- 1.5 Th2 cells per 105 PBL. In contrast, PBL from six BP patients in remission or on immunosuppressive therapy did not form IFN-gamma- or IL-5-producing spots per </= 5 x 105 PBL. The patient with oral PV had 4.7 +/- 2.4 Th1 cells and 3.0 +/- 0.4 Th2 cells per 105 PBL and a vigorous PBL response to Dsg3. In addition, three of 10 controls had BP180-reactive Th1 (2.7-13.8 per 105 PBL) and Th2 (0.3-1.8 per 105 PBL) cells and one control had 9.0 +/- 0.7 Th1 cells and 1.1 +/- 0.8 Th2 cells per 105 PBL, with reactivity to Dsg3. ELISPOT reactivity correlated with 3H-thymidine incorporation in six of seven patients and controls with autoreactive T-cell responses. CONCLUSIONS: The ELISPOT assay seems to be promising for the quantitative and qualitative analysis of autoreactive T-cell responses in BP and PV.

Autoimmunity↗

Comparison of PRA-STAT, sHLA-EIA, and anti-human globulin-panel reactive antibody to identify alloreactivity in pretransplantation sera of heart transplant recipients: correlation to rejection and posttransplantation coronary artery disease.

BACKGROUND: Screening pretransplantation recipient sera for percent panel reactive antibodies (%PRA) by an anti-human globulin (AHG) assay may identify recipients who are at risk for graft rejection or development of posttransplantation coronary artery disease. However, the pretransplantation AHG-%PRA does not always correlate with the occurrence of graft rejection or coronary artery disease. METHODS: We compared the predictive capacity of the AHG-%PRA with that of an enzyme-linked immunoassay (EIA)-based PRA assay that identifies immunoglobulin G bound to soluble human leukocyte antigen (sHLA) class I molecules from pooled platelets of 240 random donors (sHLA-EIA), and that of an EIA-based assay that detects immunoglobulin G anti-HLA class I antibodies bound to sHLA derived from individual HLA-typed cell cultures (PRA-STAT). The pretransplantation sera from 130 cardiac allograft recipients were comparatively tested and results evaluated. RESULTS: Although AHG-%PRA- and sHLA-EIA-determined PRA results were comparable, neither assay discriminated potential recipients at risk for rejection or coronary artery disease. However, cardiac allograft recipients with pretransplantation PRA-STAT sera > 10% were at risk for (1) graft rejection (77% vs 56%, p < .05); (2) more rejections/recipient (1.9 vs 1.0, p < .02); (3) graft rejection within 30 days (92% vs 38%, p < .001); or (4) development of coronary artery disease (48% vs 23%, p < .05) than recipients with pretransplantation PRA-STAT sera < 10%. CONCLUSIONS: PRA-STAT analysis of pretransplantation sera from potential cardiac allograft recipients may be more clinically informative about HLA alloimmunity and a better predictor of adverse clinical events than either AHG-%PRA- or sHLA-EIA-determined PRA.

Antibody Specificity↗

Sensitization of mice to topically applied drugs: albuterol, chlorpheniramine, clonidine and nadolol.

Allergic contact dermatitis from drugs is a significant obstacle to the development of transdermal drug delivery systems. Protocols for the sensitization of mice to drugs are needed to test methods for the prevention of allergic contact dermatitis. CBA/J female mice were sensitized to the drugs albuterol, chlorpheniramine, clonidine and nadolol by topical application. Sensitization was achieved by application of drug at 5% (w/v) to shaven dorsal skin for 5 days in a hydroxyethylcellulose vehicle. Contact sensitization was determined by measuring the ear swelling response to application of 1% drug in vehicle. Control mice treated by application of vehicle alone did not exhibit an ear swelling response to drug. Supplementation of the mice with vitamin A boosted the ear swelling response, as did application of drug to dorsal versus abdominal skin. Although plasma amounts of retinol were higher in vitamin A supplemented versus control mice, the rate of drug (albuterol and nadolol) permeation was not significantly different between vitamin A supplemented and control mice. Permeability of dorsal skin for nadolol was twice that of ventral skin, which may explain the differences in sensitization at these sites. This sensitization protocol should be useful in the development of hypoallergenic transdermal drug delivery systems.

Administration, Cutaneous↗

Lyme disease.

The clinical features of Lyme disease have been well documented since its description as a distinct clinical entity in 1975. A better understanding of the diversity of Borrelia strains and species that cause the disease as well as new insights into the immunology and pathogenesis of Lyme disease help explain some of the observed variations in clinical manifestations. The diagnosis of Lyme disease may be straightforward when patients in endemic areas present with typical clinical features; however, the diagnosis should be in doubt when the clinical picture is nonspecific or atypical, or a feasible exposure history cannot be obtained. Laboratory diagnosis is primarily based on serologic techniques, but interpretation of test results can be fraught with uncertainty. Treatment with appropriate antibiotics is successful in the majority of cases of Lyme disease. However, some patients may not respond, and in these cases multiple repeated courses are usually ineffective and unwarranted. More data are needed to determine the appropriate treatment of Lyme disease during pregnancy, and the appropriate management of ixodes tick bites. A suitable arthropod vector and a competent animal reservoir host are essential for perpetuating Lyme disease in a geographic location. The intricate ecologic forces at work are well understood in certain endemic areas but are poorly defined elsewhere, particularly where the disease is sporadic or its existence is in question. Prevention of Lyme disease is best achieved through education regarding avoidance of the tick vector. A vaccine using a recombinant form of the OspA protein of B. burgdorferi has been successful in animal models. Whether an effective human vaccine can be developed remains unknown.

Humans↗

Humana tries important entry into Chicago market.

The proposed purchase of Chicago's Michael Reese Hospital and Medical Center by Humana Inc., is hailed as one of the first such takeovers driven by the value of an HMO plan rather than the value of the parent hospital. The author discusses the proposed $50 to $70 million Reese purchase and its impact on the market.

Chicago↗