Biomedical subjects
Publications and source records attributed to A Horowitz.
A case of congenital hepatic fibrosis (CHF), a relatively rare disease, was diagnosed preoperatively on the basis of clinical and radiological findings. The diagnosis was confirmed by computerized tomography and later proven by a liver biopsy performed during cholecystectomy. Increased awareness of this entity may reveal heretofore unidentified cases of CHF.
Methane-producing freshwater lake sediment was found to dehalogenate chloro-, bromo-, and iodobenzoates by a reductive reaction in which the halogen was replaced by a hydrogen atom. The identity of the dehalogenated products was confirmed by mass spectrometry, nuclear magnetic resonance, or cochromatography. Removal of the halogens to produce benzoate was necessary before mineralization to CH(4) + CO(2) could occur. The dehalogenation occurred after a lag period which lasted from 1 week to more than 6 months, depending on the chemical. Dehalogenation was not observed in the absence of CH(4) production, and it was inhibited by the addition of 20% O(2). Once sediment was acclimated to halobenzoate dehalogenation, new additions of the halobenzoate were degraded without lag. Acclimation was observed regardless of whether the parent substrates were eventually mineralized to CH(4) + CO(2). Sediment acclimated to bromo- and chlorobenzoate degradation generally metabolized bromo- and chlorobenzoates, but sediment acclimated to iodobenzoate degradation only metabolized iodobenzoate. Prior acclimation of sediment to benzoate decomposition did not alter the pattern of dehalogenation, and sediment acclimated to dehalogenation was not concurrently acclimated to benzoate degradation. The presence of this apparent specificity, the lag period, and subsequent acclimation, together with our findings of the absence of dehalogenation in sterile sediments and by sediments previously incubated at >/=39 degrees C, suggests that this reaction was biologically catalyzed. Apparently, a pathway for the reductive dehalogenation of aryl halides is present in anaerobic microorganisms of this methanogenic sediment.
The recent emphasis on developing programs and policies to support families who care for aged relatives makes it important to understand the families' receptivity to the specific social and economic incentives under consideration. The research reported in this paper draws on the experiences of 203 individuals identified as the primary caregiver to an aged frail relative currently receiving home care or day care services in New York City. As part of a larger study of caregiving behavior, respondents were asked to rank their preferences for various service and economic support programs. Findings indicate that family caregivers perceive service and social supports, specifically medical care and homemaker service, as more crucial than both direct and indirect financial incentives. Furthermore, the issue of economic incentives elicited an extremely negative reaction from a significant minority who refused to consider such support in their personal family situations. The analysis indicated that the caregiver's background characteristics were not critical in differentiating caregivers who select either a service or an economic incentive. Among the set of variables defining the current caregiving situation, only sex of the aged relative and utilization of home care services were significantly related to choice of program. Respondents caring for females and high service utilizers were more likely to prefer service supports. Relevance of findings to current policy initiatives regarding financial incentives to families are presented.
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A non-antigenic biological dressing of amniotic membrane and skin was prepared by treatment with the enzyme ficin and dialdehyde starch. The dressing was tested in experimental animals for the coverage of full-thickness skin defects. The healing process was studied, as well as the durability of the biological dressing. Testing for flexibility, adherence and antigenicity, there was no change in the ficin-treated dressing when used even after being stored for a period of up to 2 years. The enzyme treatment did not result in a superior biological dressing.
The mitogenic response of peripheral blood lymphocytes was examined in 37 healthy individuals and in 44 patients with various malignant neoplasms. Tested individuals were divided into three major age groups (20-40; 40-60; and over 60 years of age). There was a significant decrease in Phytohemagglutinin (PHA) response with age in the normal controls, but no significant change with age was observed in the cancer patients. Comparison between the various age groups of cancer patients and their corresponding normal controls did not reveal a significant difference in mitogenic response of the young and middle age groups. However, the older cancer patients responded significantly better compared with their corresponding older normal controls. The reduced responsiveness of older normal controls was partially explained by a high activity of suppressor macrophages observed in this group. Reduction of the proportion of phagocytic cells improved their response to PHA. On the other hand, the activity of suppressor macrophages in the older cancer patients was much less prominent. These observations emphasize the importance of appropriate age grouping when immune function tests in cancer patients are compared with those performed in normal individuals and suggest the possibility of higher mitogen responsiveness in certain age groups of cancer patients.
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The tumour promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and structurally related phorbol esters effect changes in avian and mammalian cell cultures that mimic transformation by oncogenic viruses or chemical carcinogens and the inhibition or induction of various types of differentiation (for review see refs 1--3). Unlike initiating carcinogens, which seem to act by binding covalently to cellular DNA, the primary site of action of the phorbol ester tumour promoters seems to be the cell membrane; indeed, specific high-affinity saturable receptors for phorbol esters have been identified in cell membranes. The recently discovered class of tumour promoters, the teleocidins, are as potent as TPA in the induction of ornithine decarboxylase in mouse skin, the inhibition of differentiation of Friend erythroleukaemia cells, the induction of HL-60 cell adhesion and the promotion of tumours on mouse skin. As the teleocidins are structurally unrelated to the phorbol esters, we set out to determine their effects on cell membranes and receptors. We found that in rodent cell cultures, teleocidin B and dihydroteleocidin B have effects similar to those of TPA and that, at nanomolar concentrations, teleocidin inhibits the binding of phorbol esters to cell-surface receptors, which suggests that the action of both classes of compounds may be mediated by the same or a similar receptor system.
The peroral small intestinal biopsies of 5 patients with chronic malabsorption leading to a fatal course were examined retrospectively for the presence of abnormal (? premalignant) cells. Techniques employed for their identification included routine histology, immunofluorescence, immunohistochemistry (horseradish peroxidase) and electron microscopy. The biopsies of 3 other patients, 2 with known lymphoma and 1 with alpha chain disease were examined for any similarity in the ultrastructural appearances of abnormal cells and their immune cellular behaviour in these 2 groups of patients. Fine structural identification of cells displaying either nuclear or cytoplasmic abnormalities was possible in all 8 patients and varied from easily identifiable cell types, like the plasma cell, lymphocyte or histiocyte to those possessing more than one characteristic feature. The immunological staining techniques did not help in the identification of these abnormal cells. We conclude that careful E.M. examination of the mucosal cellular infiltrate in patients with chronic malabsorption can make a valuable contribution in identifying diffusely abnormal cells, though it may not be possible to determine whether they are of histiocytic or lymphocytic origin.
A case is presented in which a huge cystic mass adjacent to the outline of a 29-wk fetus was identified by ultrasonography. After delivery this was proven to be a common cloaca in a fetus with multiple congenital anomalies. The possible mechanisms of this anomaly are discussed.
An unusual case of a degenerative cyst, causing median nerve compression within the carpal tunnel, is reported.
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The effects of the size of acute myocardial infarction on ventricular reentry and automaticity were studied in 36 mongrel dogs. Large transmural myocardial infarctions were produced by ligation of the left anterior descending coronary artery (major ligation; diameter of infarction above 4.0 cm), and small subendocardial or intramural infarctions were produced by ligating a small diagonal branch of the left anterior descending coronary artery (minor ligation; diameter of infarction less than 1.5 cm). Reentrant arrhythmias were induced by rapid ventricular stimulation, and ventricular automaticity was determined during vagal stimulation. Ventricular automaticity became enhanced only 30 to 45 minutes after both major and minor coronary arterial ligations; however, the animals with major ligations attained a higher level of increased automaticity. While automaticity became enhanced in both groups reentrant arrhythmias could never be produced artificially (or observed spontaneously) in the animals with myocardial infarctions. The dependence of the so-called reentrant arrhythmias on the size of the infarction is a major support for the theory of reentry as the basis for these arrhythmias.
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A variety of marine biota, including zooplankton, sargassum, surface plankton, squid, shrimp, and fish collected along the south Texas Outer Continental Shelf, were analyzed for Cu, Zn, Cd, Pb, Cr, Ni, Fe, and Mn. Although there is a great deal of variation in the chemical content of the various samples, both within species and between species, the variations all fall within the range of values published for similar organisms collected elsewhere. An increase in Pb concentration from north to south, and an increase in Cd concentration from nearshore to further offshore in the zooplankton mirrors the sediment patterns. Statistical analysis of the chemical and biological data for these samples indicates that relatively small percentages of the biological makeup of the sample can markedly affect the concentrations of Pb, Cd, Ni, and Zn. This is particularly true for the larvacea, ostracoda, and mollusca. Chemical analyses of the exoskeletons of shrimp and the skin of both squid and fish indicate that they generally contain higher metal levels in comparison with the flesh from the same organism. This is probably the result of either adsorption from seawater and/or an internal detoxification procedure employed by the organism. The analysis of a composite sample of squid 'pens' indicates that they contain enriched Cu, Cd, Zn, Pb, and Fe levels in comparison with the skin and flesh. These elevated levels are probably the result of an internal detoxification procedure and/or may represent a means of storing necessary metabolites, at least in the case of Cu and Zn, but can not be attributed to adsorption as the chitinous 'pen' is imbedded in tissue and is not directly exposed to seawater.
A continuous flow-through system incubated in situ was used to model oil biodegradation in Arctic coastal waters. High numbers of oil-degrading microorganisms were found in the Arctic coastal waters examined in this study. The microbial community underlying oil slicks increased and showed a population shift to a greater percentage of hydrocarbon-utilizing microorganisms. Microbial populations and oil biodegradation were increased by the addition of nitrogen and phosphorus. Both abiotic and biodegradative losses were lower than expected, perhaps due to the unusually harsh, ice-dominated Arctic summer, during which these tests were conducted. Chromatographic and spectrometric analyses showed that residual oils contained similar percentages of individual components and classes of hydrocarbons, regardless of the amount of degradation, indicating that most components of the oil were being degraded at similar rates.