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Biomedical subjects

S Katz

Publications and source records attributed to S Katz.

At least 379 records · Page 21Linked to original sources
PubMed1982

The use of fluoride and chlorhexidine for the prevention of radiation caries.

A regime of four topical applications of 1.0% sodium fluoride-1.0% chlorhexidine digluconate plus daily rinses with an 0.05% sodium fluoride-0.2% chlorhexidine solution prevented radiation caries completely. It also resulted in remineralization of incipient existing lesions. Use of the chlorhexidine-fluoride rinses alone also stopped radiation caries but did not permit remineralization to occur. Use of four topical applications with a fluoride gel and daily rinses with an 0.05% sodium fluoride solution was not sufficient to prevent radiation caries. No chlorhexidine staining was observed. The patients' acceptance of and compliance with the program and the rinses was excellent.

Chlorhexidine↗
PubMed1981

Renal localization of the membrane attack complex in systemic lupus erythematosus nephritis.

The membrane attack complex (MAC) of the complement system was localized in both glomeruli and peritubular regions of 22 kidneys manifesting systemic lupus erythematosus (SLE) nephritis. A similar distribution was observed for immune complex markers (IgG, Clq, and C3) and MAC in glomeruli, although the deposits of MAC were more discrete and showed lesser immunofluorescence staining intensity compared with immunoglobulins and complement components. In contrast, peritubular immune complexes were present in only 7 out of 22 kidneys, involved comparatively small clusters of tubules, exhibited weaker immunofluorescence staining than MAC, and failed to correlate with interstitial foci of inflammation. Granular or irregular, linear aggregates of the MAC were observed at the periphery of larger groups of tubules contiguous to areas of interstitial inflammation. Comparable amounts of IgG, Clq, C3, and MAC were present in blood vessel walls in areas of fibrinoid necrosis. These data suggest that the MAC is a direct mediator of tissue injury occurring in renal glomeruli, tubules, and blood vessels. The discordance between immune complexes and MAC localized in the peritubular region, but not in glomeruli or blood vessels, raises the possibility that both immune complexes and nonimmune agents, such as bacterial antigens, may activate the classical or alternative complement pathways and thereby play a role in the pathogenesis of tubulointerstitial lesions of SLE nephritis.

Animals↗
PubMed1981

Calmodulin regulation of Ca2+ transport in human erythrocytes.

Inside-out vesicles of human erythrocytes took up Ca2+ against an electrochemical gradient. This Ca2+ uptake was dependent on ATP and was stimulated by calmodulin. Treatment of vesicles with 1 mM-EDTA exposed an apparent low-CA2+-affinity Ca2+-transport component with Kd of about 100 microM-Ca2+ or more. This was converted into a single high-Ca2+-affinity transport activity of Kd about 2.5 microM-Ca2+ in the presence of 2 micrograms of calmodulin/ml, showing that the decrease in transport activity after EDTA treatment was reversible. Vesicles not extracted with EDTA showed mainly apparent high-Ca2+-affinity kinetics even in the absence of added calmodulin. Trifluoperazine (30 microM) and calmodulin-binding protein (20 micrograms/ml) inhibited about 50% of the high-affinity Ca2+ uptake and (Ca2+ + Mg2+)-ATPase (Ca2+-activated, Mg2+-dependent ATPase) activity of these vesicles, indicating that the vesicles isolated by the procedure used retained some calmodulin from the erythrocytes. Comparison of Ca2+ transport and (Ca2+ + Mg2+)-ATPase activities in inside-out vesicles yielded a variable Ca2+/P1 stoichiometric ratio. At low free Ca2+ concentrations (below 20 micro-Ca2+), a Ca2+/P1 ration of about 2 was found, whereas at higher Ca2+ concentrations the stoichiometry was approx. 1. The stoichiometry was not significantly altered by calmodulin.

Adenosine Triphosphatases↗
PubMed1981

The effect of calmodulin on the phosphoprotein intermediate of Mg2+-dependent Ca2+-stimulated adenosine triphosphatase in human erythrocyte membranes.

The effect of calmodulin on the formation and decomposition of the Ca2+-dependent phosphoprotein intermediate of the (Mg2+ + Ca2+)-dependent ATPase in erythrocyte membranes was investigated. In the presence of 60 microM-Ca2+ and 25 microM-MgCl2, calmodulin (0.5-1.5 microgram) did not alter the steady-state concentration of the phosphoprotein, but increased its rate of decomposition. Higher calmodulin concentrations significantly decreased the steady-state concentration of phosphoprotein. Calmodulin (0.5-1.7 microgram) increased Ca2+-transport ATPase activity by increasing the turnover rate of its phosphoprotein intermediate. Increasing the MgCl2 concentration from 25 microM to 250 microM increased the (Mg2+ + Ca2+)-dependent ATPase activity, but decreased the concentration of the phosphoprotein intermediate. Similarly to calmodulin, MgCl2 increased the turnover rate of the Ca2+-transport ATPase complex (about 3-fold). At the higher MgCl2 concentration calmodulin did not further affect the decomposition of the phosphoprotein intermediate. It was concluded that both calmodulin and MgCl2 increase the turnover of the Ca2+-pump by enhancing the decomposition of the Ca2+-dependent phosphoprotein intermediate.

Calcium-Binding Proteins↗
PubMed1981

An in vivo model for studying adherence of intestinal pathogens.

A new method for preparing an isolated colonic loop in a living rabbit is described. The loop with its intact neurovascular supply can be used as as a "living test tube" to study the adherence of microorganisms to intestinal mucosa. Moreover, the clear colonic mucus produced by the loop can be used to study its physiochemical nature and protecting properties in health and disease.

Adhesiveness↗
PubMed1981

Enumeration of lymphocytes and their subpopulations identified by bacterial adherence in blood smears of patients with breast tumors.

Peripheral blood lymphocyte counts were determined in 57 breast clinic patients. These patients were grouped into four clinical/pathological groups: 18 had benign breast disease, 13 had a history of breast cancer but were free of disease at the time of the study, 7 had a history of breast cancer and were free of disease at the time of the study but were on adjuvant chemotherapy, and 19 had active metastatic breast cancer. Two parameters were investigated in a double blind study: 1) the absolute lymphocyte counts and 2) the percentages of lymphocytes that bound different bacteria as markers of lymphocyte subpopulations in conventionally stained blood smears. A significant reduction in mean lymphocyte counts was demonstrated in patients with advanced disease. A significant increase in these counts was found in patients who were free of disease following surgical treatment alone. The T1T2 cells (our denomination), the subpopulation of cells responsible for specific killing in vitro and for suppression of natural cytotoxic cells, was significantly reduced in patients with advanced disease under treatment. The T/B cell ratio in all groups was the same and within normal range. These observations suggest that the observed decrease in the total lymphocytes is due not only to an overall decrease in all classes of lymphocytes but especially in those responsible for specific cell-mediated reactions. They also show that bacteria can be used as reliable reagents for the identification of lymphocyte subpopulations in blood smears.

Adult↗
PubMed1981

Relative blue-light extinction in lens nucleus related to age and cataract.

The extent of visual function loss from nuclear cataractous change can be estimated by observing the extinction of blue light compared to white light as a function of sagittal lens depth in standard slit lamps. Apparent extinction (loss of transmissivity) of 50% or more of the depth of the lens in blue light of maximal intensity compared to white light at minimal intensity is associated with marked visual loss. However, this transmissivity ratio of 0.5 or less also applies if light intensity remains constant and the blue filter is simply moved in and out of the light beam. Therefore, if 50% or more of the lens appears dark to blue-filtered light, nuclear changes have significantly decreased effective visual acuity. Relative blue-light extinction associated with nuclear change that may be amenable to surgical correction can thus be distinguished from the extinction effect caused by age alone.

Adolescent↗
PubMed1981

Repair of the injured spleen.

Splenic laceration is the most frequent visceral injury requiring laparotomy after blunt abdominal trauma in children. Splenectomy increases the risk of overwhelming bacterial infection which could prove fatal. This paper reports four patients with splenic injury who were treated by splenic repair.

Adult↗
PubMed1981

Bacterial adherence to surgical sutures. A possible factor in suture induced infection.

Surgical sutures are known to potentiate the development of wound infection. The purpose of this study was to investigate whether the capability of bacteria to adhere to various types of sutures has a significant effect on their ability to cause infections. Bacterial adherence to sutures was quantitatively measured using radiolabeled bacteria. In vitro adherence assays revealed remarkable variations in the affinity of bacteria to the various sutures: nylon bound the least bacteria while bacterial adherence to braided sutures (silk, Ti-cron, Dexon) was five to eight folds higher. The degree of infection obtained in mice in the presence of different sutures nicely correlated with their adherence properties. The different removal rate of adherent bacteria (glutaraldehyde-fixed) from various sutures by the tissue factors in mice supports the hypothesis that bacterial adherence to suture materials plays a significant role in the induction of surgical infection. Our observation points out at the need for careful suture selection in contaminated wounds. The adherence properties of sutures should be considered in any future surgical suture design.

Animals↗
PubMed1981

Immunofluorescence mapping of antigenic determinants within the dermal-epidermal junction in the mechanobullous diseases.

The classification of mechanobullous diseases often depends on the electron microscopic distinction of intradermal (dermolytic), junctional and intraepidermal sites of cleavage. Electron microscopy is tedious and time consuming. In this report we describe a different approach to the determination of the cleavage plane by using a method which recognizes subtle differences in the localization of antigenic structures relative to the cleavage plane. Cryostat sections of lesional and extralesional skin of 3 patients with dermolytic epidermolysis bullosa, 3 with epidermolytic epidermolysis bullosa and 8 with junctional epidermolysis bullosa were examined by immunofluorescence, with specific antisera against type IV collagen (localized within the basal lamina); against laminin (noncollagenous protein, localized in the lamina lucida); and with bullous pemphigoid antibodies (directed against the bullous pemphigoid antigen localized in the lamina lucida). All specimens were also examined by electron microscopy. In dermolytic epidermolysis bullosa (where cleft formation occurs intradermally) type IV collagen, laminin and the bullous pemphigoid antigen were consistently found in the roof of the blister, whereas in junctional epidermolysis bullosa (where the cleft occurs in the lamina lucida) type IV collagen and laminin were found on the floor of the blister whereas bullous pemphigoid antigen was present mainly on the roof, but focally also on the floor, of the blister. In epidermolytic epidermolysis bullosa (where the cleft is intraepidermal) all antigens were localized below the cleavage plane. In all cases electron microscopy confirmed the level of cleft formation predicted from the immunofluorescence mapping of the antigenic sites. The described method equals electron microscopy in accuracy but it is more rapid and simpler to perform.

Collagen↗
PubMed1981

Increased copper metallothionein in Menkes cultured skin fibroblasts.

Menkes fibroblasts contain a significantly greater amount of cysteine-rich 10,000 dalton copper-binding protein(s) (metallotheionein) than normal cells. Mutant fibroblasts incorporated 30 to 40% more tritiated amino acids into 10,000 dalton protein(s) than normal cells. The protein(s) was deficient in aromatic amino acids The amount of 35S-cysteine incorporated by the same protein(s) in Menkes fibroblasts was twice that of normal fibroblasts. Comparison of the 35 S:3H isotopic ratios of chromatographic fractions of both normal and Menkes cell lysates showed that only the proteins eluted in the 10,000 dalton peak were enriched in 35S-cysteine, and this ratio was always greater than in Menkes than in normal cells. The 10,000 molecular weight 35S-cysteine- and 3H-amino acid-labeled peaks coincided with the 64Cu peak in both cell strains. The copper-labeled peak was always greater in Menkes than in normal cells. No difference in the 64Cu:35S isotopic ratio in the 10,000 dalton peak was observed between normal and Menkes fibroblast strains. This finding shows the direct relationship between the amount of cysteine-rich 10,000 dalton protein(s) and the amount of 64Cu bound by this protein(s) in both Menkes and normal fibroblasts. DEAE-cellulose ion-exchange chromatography resulted in a further two-fold enrichment of the 10,000 dalton, sulfur-rich proteins that were eluted from the Sephadex G-75 column. Most of the labeled proteins from both normal and Menkes fibroblasts were eluted from the ion-exchange column in a single peak at a chloride concentration of approximately 30 mM. Polyacrylamide disc gel electrophoresis of pooled fractions of the 10,000 dalton proteins eluted from the G-75 column and the DEAE-cellulose ion-exchange column showed no consistent differences in the staining pattern between normal and mutant fibroblast strains. When th acrylamide gels were sliced and subsequently counted for radioactive content, no band showed a further increase in the 35 S:3H isotopic ratio when compared to the electrophoresed samples that were eluted from the Sephadex G-75 or the ion-exchange columns. Also, no significant increase in the amount of radioactivity associated with a specific protein band could be demonstrated between the Menkes and the normal fibroblast strains.

Amino Acids↗