Superior accuracy of anatomic positioning with echocardiographic- over fluoroscopic-guided endomyocardial biopsy

To assess the superior anatomic positioning of echocardiographic-guided endomyocardial biopsy compared to traditional fluoroscopic-guided technique, these two modalities were compared in a blinded fashion during femoral sheath endomyocardial biopsy in 21 patients, 19 being evaluated after orthotopic cardiac transplantation. The simultaneous fluoroscopic and echocardiographic imaging indicated that traditional fluoroscopic positioning of the bioptome against the septum is inaccurate in over half of patients undergoing biopsy. This finding should be considered in cardiomyopathy patients or those at high risk for biopsy-related complications. © 1993 Wiley-Liss, Inc.     

Norfloxacin (MK-0366, AM-715): In vitro activity and cross-resistance with other organic acids including quality control limits for disk diffusion testing

Norfloxacin is a new organic acid antimicrobic with an expanded spectrum that includes Staphylococcus spp, most Pseudomonas spp, Acinetobacter calcoaceticus ssp anitratus, some streptococci, as well as nearly all enteric bacilli. The drug appears to be bactericidal. Its expanded spectrum suggests that it should be tested separately by disk diffusion or other susceptibility testing methods. Tentative norfloxacin disk test quality control limits were derived from the results of a multi-laboratory study: Escherichia coli, 28–36 mm; S. aureus, 17–28 mm, and Pseudomonas aeruginosa, 22–29 mm.     

Oncogenicity of murine mammary tumor virus produced in tissue culture: brief communication.

Murine mammary tumor virus (MuMTV), produced from a glucocorticoid-stimulated C3H mouse mammary adenocarcinoma cell line, was free of murine leukemia virus and oncogenic for weanling BALB/c mice. Adenocarcinomas were induced by MuMTV as early as 136 days post inoculation and with as low as 5 X 10(3) virus particles/mouse. Tumor incidence did not correlate directly with virus dose; rather, it was low at higher MuMTV concentrations (1.2 X 10(8) particles/mouse), reached and optimum at 1.3 X 10(5) particles/mouse, and decreased with virus dilution.     

The appearance, density and distribution of melanocytes in human embryonic and fetal skin revealed by the anti-melanoma monoclonal antibody, HMB-45

Summary The presence, densities, and patterns of distribution of melanocytes in the epidermis of human embryos and fetuses, ranging in age from 40 d to 140 d estimated gestational age (EGA), were studied using the HMB-45 monoclonal antibody that recognizes an antigen in melanoma cells and fetal melanocytes. Immunostained sections of skin and epidermal sheets revealed dendritic melanocytes within the basal or intermediate layers of 50 d EGA and older skin. Melanocytes could not be identified by immunostaining or electron microscopy in younger (40–50 d EGA) epidermis or in cultured epidermal cells from these specimens. However, skin from a 45 d EGA embryo grown in organ culture for 11 d stained positively with HMB-45, suggesting that melanocytes are present at that age either in the epidermis or dermis of the explant. Double-labeling experiments using ATPase and HMB-45 confirmed the specificity of HMB-45 for melanocytes and demonstrated that melanocytes and Langerhans cells are nonoverlapping populations. Melanocytes were present in the embryonic epidermis in relatively high numbers (mean value of 1050 cells/mm²); they increased in density to 2300 cells/mm² during the late first trimester and early second trimester, then declined during later stages of development to a density of 800 cells/mm², within the range of values for the newborn child and young adult. Equivalent numbers of melanocytes were recognized by silver staining and with the HMB-45 antibody in an 87 d EGA test sample, indicating that HMB-45 reacted with the total melanocytic population. Melanocytes appeared to be distributed in epidermal sheets in a regular pattern. Statistical tests used to evaluate the randomness of a population revealed a tendency toward a non-random distribution in specimens younger than 80 d EGA, just prior to appendage formation and epidermal stratification into multiple layers, however there was variability in the degree of randomness for any given age. The results of this study have closed the gap in timing between the conclusion of neural crest formation and migration (around 6 weeks) and the appearance of melanocytes in the skin between 40–50 d EGA.Portions of this work were presented at the annual meeting of the Society for Investigative Dermatology, May, 1987 and at the 37th Annual Symposium on the Biology of Skin, October, 1987     

Experimental asbestos carcinogenesis

Laboratory rodents were exposed to one of three mineralogical types of asbestos dust, amosite, crocidolite, or chrysotile. Inhalation exposures were accomplished in chambers where ballmilled specimens of these dusts were disseminated for 4 hours daily, 4 days weekly, at a mean atmospheric concentration of about 48 mg/m³. Additional animals were injected with these dusts intratracheally, intrapleurally, or intraperitoneally. Histopathologic studies showed a fibrotic reaction in all species to all three types of dusts, with amosite provoking the strongest such response especially in guinea pigs. Two pulmonary cancers were produced in rats exposed to the inhalation of crocidolite. Local injection into the pleural or peritoneal cavities caused 5 mesotheliomas in rats after chrysotile treatment and 6 mesotheliomas in rats and rabbits after crocidolite treatment. Guinea pigs and hamsters developed no tumors in this experiment, and with the dose used, there were no tumors in any species in the amosite group.