Biomedical subjects
Publications and source records attributed to F G Silva.
A case of multiple myeloma with intra- and extracapillary proliferative glomerulonephropathy and other unusual morphologic and clinical manifestations is described. The probable role of light chain proteins in the pathogenesis of the glomerular lesions is discussed. Evidence is presented documenting the beneficial effects of appropriate therapy on the activity and progression of the renal lesions.
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The present study was undertaken using light and electron microscopic techniques to determine whether Purkinje fibers survive in the subendocardial region of anteroseptal infarcts in humans. Tissue was obtained for this purpose from 11 patients with 12 documented infarctions at the time of autopsy; six patients died within 72 hours of the infarction and five had healed infarcts. Seven of the 11 patients had ventricular arrhythmias. Light microscopic study indicated that intact cells with a normal appearance remained on the subendocardial surface, although the underlying ventricular muscle either was necrotic or was replaced by fibrous tissue. Electron microscopy demonstrated that these intact surviving cells over the surface of the infarct had few randomly oriented myofibrils, abundant glycogen, and other characteristics of Purkinje fibers. These cells could be readily distinguished from normal or infarcted ventricular muscle cells. Purkinje fibers, the most peripheral part of the conduction system, survive in extensive anteroseptal infarcts and may be the site of origin of ventricular arrhythmias.
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In a previous study, utilizing antibodies to proliferating cell nuclear antigen (PCNA), we determined the proliferation index (PI) (percentage of PCNA-positive cells) of intrinsic renal cell populations in the normal adult and pediatric kidney. We have found that the PI in both adult and pediatric kidneys was very low (below 0.5 in all examined cell populations). In our present study, we investigated cell proliferation in the developing human kidney with an antibody to PCNA. Histologically normal kidneys were collected from 25 fetuses (spontaneous abortions and stillborns) ranging from 10 wk of gestation to term. Immature mesenchyme (blastema), immature early tubules, ampulla of ureteric bud, proximal tubules, Tamm-Horsfall protein (THP)-positive tubules, distal tubules, collecting ducts, and glomeruli were evaluated separately. The PI for each cell population was calculated. The PI of immature early tubules remains high (33-43) throughout embryonic life. The PI of blastemal cells is initially similarly high, but gradually decreases starting from the second trimester. The PI of THP-positive tubules, distal tubules, collecting ducts, and glomeruli starts out relatively high (5.9, 8.6, 6.0, and 12.4, respectively) and decreases gradually as term approaches (1.8, 1.3, 1.2, and 1.4, respectively). Interestingly, as soon as proximal tubules become differentiated (appearance of light microscopic features of proximal tubular epithelium with TP lectin positive brush border), their PI becomes very low (below 1) irrespective of the age of the kidney. This is the first quantitative study to show changes of the PI in various renal cell populations during human nephrogenesis. These changes in the PI relate to the stage of differentiation of the developing nephron segments.
Diabetes mellitus and surgical ablation of renal tissue are two independent influences associated with hyperfiltration and elevated levels of the glomerular transcapillary hydraulic pressure differential (delta P). There is increasing evidence that hyperfiltration with elevated delta P is pathogenic and leads to glomerular damage. The authors questioned whether these two influences (surgical ablation of renal tissue and diabetes mellitus) would act in an additive fashion in human patients to produce an accelerated decline in renal function. Three patients with non-insulin-dependent diabetes mellitus who had undergone a unilateral nephrectomy (for a variety of reasons) were (retrospectively) identified. In each patient, morphologic evidence of diabetic glomerulonephropathy was present in the resected kidney. The charts from these patients were reviewed and post-nephrectomy renal function was estimated over time by plotting reciprocal serum creatine values versus time. Follow-up intervals after nephrectomy varied from 4 to 15 years. The results of our follow-up showed no obvious detrimental effect on renal function (as measured by 1/serum creatinine) attributable to the unilateral nephrectomy. The authors conclude that residual renal function (and ultimate outcome) in patients with non-insulin-dependent diabetes mellitus is highly variable, but does not seem to be adversely affected (at least over the time span of observation in these patients) by unilateral nephrectomy.
Trichoderma harzianum strains T4 and T6, Acrophialophora nainiana, and Humicola grisea var. thermoidea were screened for their ability to produce carbohydrate-degrading enzyme activities in a medium containing banana plant residue as the carbon source. The best balance of enzyme activities was obtained from cultures of H. grisea var. thermoidea. Xylanase activity from crude extract of A. nainiana had a maximum activity at pH 5.5-7.0 and a temperature range of 50-55 degrees C. It was stable up to 55 degrees C at pH 7.0 for at least 2 h. The fungi were also able to produce xylanase and pectinase activities when grown on extractives as substrate.