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Biomedical subjects

S Katz

Publications and source records attributed to S Katz.

At least 325 records · Page 18Linked to original sources
PubMed1985

Aphthous ulcers in ischemic gastroenterocolitis: a case report.

Extensive occlusive mesenteric vascular disease is described in a 41-year-old man, resulting in aphthous ulcers of the stomach, small bowel, and colon. Ischemic disease was confirmed angiographically and ultimately by surgical intervention. No evidence of inflammatory bowel disease was detected. Occlusive vascular disease must be considered in the differential diagnosis of aphthous ulcers of the gastrointestinal tract. The risks of angiography may be warranted in the presence of atypical and unresponsive inflammatory bowel disease, especially when it coexists with vascular disease elsewhere.

Adult↗
PubMed1984

Ca2+-ATPase activity in pancreatic acinar plasma membranes. Regulation by calmodulin and acidic phospholipids.

A high degree of ATP hydrolytic activity present in purified rat pancreatic acinar cells was localized to plasma membranes. This activity was stimulated almost equally by Mg2+ or Ca2+. Kinetic analysis revealed that the enzyme had a higher affinity for Ca2+ (Kd = 1.73 microM) than Mg2+ (Kd = 2.98 microM) but a similar maximal rate of activity. A comparison of substrate requirements revealed very similar profiles for the Mg2+- and Ca2+-stimulated activities. Combinations of saturating concentrations of Mg2+ or Ca2+ produced the same degree of maximal activity. Investigation of the partial reactions of the ATPase activity revealed two phosphoprotein intermediates (Mr = 115,000 and 130,000) in the presence of Ca2+ and Mg2+. A significant stimulation of the Ca2+-ATPase activity by calmodulin was observed (Kd = 0.7 microM). Calmodulin increased the Ca2+-sensitivity of this enzyme system; Mg2+ appeared to be required for this effect. The Ca2+-ATPase activity was also stimulated by acidic phospholipids. Using an 125I-labeled calmodulin gel overlay technique, calmodulin was shown to bind in a Ca2+-dependent fashion to 133,000- and 230,000-dalton proteins present in the plasma membrane-enriched fraction. Under conditions that favor Ca2+-dependent kinase activity, calmodulin enhanced the phosphorylation of a 30,000- and 19,000-dalton protein. The major ATP hydrolytic activity in pancreatic acinar plasma membranes was present as an ectoenzyme.

Adenosine Triphosphatases↗
PubMed1984

Circadian changes in carrageenin-induced edema: the anti-inflammatory effect and bioavailability of phenylbutazone in rats.

The circadian variations in paw-edema produced by carrageenin and the anti-inflammatory effect of phenylbutazone were studied, in rats kept under a 12 light-12 dark regimen, in comparison with the variations of plasma phenylbutazone and oxyphenbutazone levels. When the experiment was performed during the light span (08.00 and 14.00 h), the rats were highly sensitive to the phlogistic effect of carrageenin, the plasma levels of phenylbutazone and oxyphenbutazone were lower, and the anti-inflammatory effect of phenylbutazone, weaker. Opposite results were obtained when the experiment was performed during the dark span (02.00 and 20.00 h). The results indicate that the chronoeffectiveness of phenylbutazone is influenced by both its chronokinetics and the chronesthesy of the biosystem involved.

Animals↗
PubMed1984

Does calmodulin play a role in the regulation of cardiac sarcolemmal adenylate cyclase activity?

The recent suggestion that calmodulin (CaM) could mediate calcium inhibition of cardiac adenylate cyclase (AC) has been reassessed. Using a purified sarcolemmal preparation (SL), the influence of different concentrations of free Ca2+ (obtained using Ca2+-EGTA solutions) was studied on dog heart AC. From 10(-9) M to 10(-3) M Ca2+ reduced basal activity, as well as epinephrine (10(-4) M)- and trypsin (1.0 microgram/mL)-stimulated activities with, in the three cases, an identical IC50 of 10(-8) M. The amount of endogenous CaM in the SL, measured using a radioimmunoassay technique, was found to be 7.5 ng/mg protein. The resulting concentration of CaM in the final AC incubation medium was lower than 50 pM, indicating the lack of a significant role for endogenous CaM in the inhibition observed. The addition of exogenous CaM to the AC assay at a concentration sufficient to stimulate other CaM-dependent systems did not modify the Ca2+ inhibitory curves for basal, epinephrine (10(-4) M)-stimulated, or trypsin (1 microgram/mL)-stimulated activities. These results indicate that CaM does not play a significant role in the Ca2+ inhibition of cardiac AC and that trypsin stimulation of cardiac AC is not mediated through a CaM-dependent process.

Adenylyl Cyclases↗
PubMed1984

The presence and binding characteristics of calmodulin in microsomal preparations enriched in sarcoplasmic reticulum from rabbit skeletal muscle.

ATP-dependent oxalate facilitated calcium transport in sarcoplasmic reticulum (SR) preparations obtained from rabbit vastus lateralis muscle (fast skeletal muscle; Fsr) and soleus (slow skeletal muscle; Ssr) was determined. Addition of exogenous calmodulin did not stimulate calcium transport in either Fsr or Ssr preparations. Fsr and Ssr previously washed in 1 mM EGTA demonstrated a reduced capacity to transport Ca2+; the exogenous addition of calmodulin (0.24 microM) under these conditions, did not restore uptake activity but significantly decreased the steady-state level of Ca2+ uptake. Extracts of skeletal SR prepared by treatment with 0.2 mM EDTA and boiling produced significantly more stimulation of red cell Ca2+ATPase activity than extracts prepared by boiling alone. This stimulation of red cell Ca2+-ATPase was inhibited to a significant extent by 48/80, a known anti-calmodulin agent. Radioimmunoassay revealed that extracts prepared by boiling or EDTA-treatment followed by boiling contained considerable amounts of calmodulin. Washing with 1 mM EGTA, though, did not release any calmodulin from SR. These studies reveal that calmodulin is present in both Fsr and Ssr and can only be removed by harsh treatments. The role of calmodulin in skeletal muscle Ca2+-transport remains to be determined.

Animals↗
PubMed1984

The calcium hypothesis of cystic fibrosis.

Data have been presented which suggests that various CF cell types show evidence of alterations in calcium homeostasis. The significance of these observations and the exact nature of the putative calcium defect in CF remains to be elucidated. It must also be determined whether this possible defect is primary, or is secondary or tertiary to some more basic lesion. The data reviewed suggests that altered calcium homeostasis may play some focal role in the aetiology or the pathogenesis of CF.

Calcium↗
PubMed1984

Depression of calcium transport in sarcoplasmic reticulum from diabetic rats: lack of involvement by specific regulatory mediators.

Cardiac sarcoplasmic reticulum (SR) ATP-dependent Ca2+-uptake was found to be depressed in 4 month streptozotocin-induced diabetic rats. Calmodulin, cAMP-dependent protein kinase and K+ stimulated Ca2+-uptake to similar degrees in SR from both control diabetic rats. Long chain acylcarnitine (7 microM) decreased Ca2+-transport in control rats by 46% but only 26% in diabetic animals. The data suggests that the depression in cardiac SR Ca2+-uptake activity in diabetic rats is non-specific in origin and not a result of alterations in regulation of SR function.

Adenosine Triphosphate↗
PubMed1984

Laboratory basis for the medical management of necrotizing enterocolitis (NEC).

Necrotizing enterocolitis (NEC) is a serious condition affecting the neonate that may be responsive to medical management. This study evaluates the efficacy of supplemental oxygen (FiO2 40% and 50%), systemic antibiotics (ampicillin and gentamicin, cephamandole) and oral antibiotics (trimethoprim-sulfamethoxazole, neomycin and gentamicin) in a weanling rat bowel ischemia model induced by a transient (one minute) occlusion of the superior mesenteric artery. Animals were evaluated for overall survival, duration of survival, presence of bowel necrosis or perforation at seven days. Mortality in ischemic controls was 83.8%. This was reduced to 52% by FiO2 of 50%, and 40% with systemic ampicillin and gentamicin (with or without FiO2 50%) (P less than .001). Length of survival was 3.4 days in controls and increased from 5.4 to 5.9 days in rats given FiO2 50% and/or ampicillin and gentamicin (P less than .001). The incidence of bowel necrosis in controls was 60% and was reduced to 25% in rats given systemic ampicillin and gentamicin and 23.3% with 50% FiO2 and the same antibiotics (P less than .001). Systemic cephamandole and oral antibiotics had no beneficial effects.

Animals↗
PubMed1984

Impaired bacterial clearance and trapping in obstructive jaundice.

Sepsis is a major cause of mortality in patients with common bile duct obstruction. To define possible contributing factors to this phenomenon, this study evaluates the effect of biliary obstruction on the intravascular clearance and organ trapping of viable Escherichia coli using a rat model. Adult male Sprague-Dawley rats were placed in three groups: Group I controls had sham operation, Group II had division and ligation of common bile duct (CDL), and Group III underwent splenectomy. At 21 days following operation 10(9) radiolabeled E. coli were injected intravenously. At varying intervals after infusion, blood samples were obtained for clearance study. At 10 minutes, bacterial distribution in the liver, spleen, kidneys, and lungs was determined (expressed as the mean percentage of injected viable E. coli). Intravascular clearance was similar in all groups. There was a significant decrease in the trapping of bacteria by the liver of CDL rats 14.5% +/- 4.95 (vs. control = 70.0% +/- 13.3) (p less than 0.005). A significant increase of bacterial trapping by the lung was observed in the CDL animals: 63.1% +/- 7.06 (vs. controls 1.4% +/- 0.82) (p less than 0.005). There was no significant change in bacterial localization in splenectomized rats. These data suggest that biliary obstruction decreases hepatic phagocytosis and increases pulmonary localization of viable E. coli. As the Kupffer cells of the liver are usually effective in removal of blood borne bacteria, this phagocytic dysfunction may contribute to the increased susceptibility to infection noted in instances of biliary obstruction.

Animals↗
PubMed1984

Mechanisms and pathways of aniline elimination from aquatic environments.

The fate of aniline, a representative of arylamine pollutants derived from the manufacture of dyes, coal liquefaction, and pesticide degradation, was comprehensively evaluated by use of unpolluted and polluted pond water as model environments. Evaporation plus autoxidation proved to be minor elimination mechanisms, removing ca. 1% of the added aniline per day. Instantaneous binding to humic components of a 0.1% sewage sludge inoculum removed 4%. Biodegradation of aniline in pond water was accelerated by the sewage sludge inoculum. A substantial portion of the degraded aniline carbon was mineralized to CO2 within a 1-week period, and microbial biomass was formed as a result of aniline utilization. Biodegradation was clearly the most significant removal mechanism of polluting aniline from pond water. A gas chromatographic-mass spectrometric analysis of biodegradation intermediates revealed that the major pathway of aniline biodegradation in pond water involved oxidative deamination to catechol, which was further metabolized through cis,cis-muconic, beta-ketoadipic, levulinic, and succinic acid intermediates to CO2. Minor biodegradation pathways involved reversible acylation to acetanilide and formanilide, whereas N-oxidation resulted in small amounts of oligomeric condensation products.

Aniline Compounds↗
PubMed1984

Temperature sensitivity of the renin-angiotensin system in Ambystoma tigrinum.

The presence of a renin-angiotensin system was demonstrated in the poikilotherm Ambystoma tigrinum, commonly called the tiger salamander. Standard radioimmunoassay techniques were employed to measure the intrarenal renin activity (IRA) and the plasma renin activity (PRA) of A. tigrinum kept at either 5 or 20 degrees C. Basal IRA and PRA values were not affected by the temperature at which the animals were maintained. Intraperitoneal injection of the beta-adrenergic agonist isoproterenol, however, increased PRA only in those animals maintained at 20 degrees C. This is consistent with the hypothesis of a temperature sensitivity of the renal adrenergic system in vivo. In addition, we were able to demonstrate the existence of a contractile response of Ambystoma vascular smooth muscle to angiotensin II that was blocked by the competitive inhibitor saralasin.

Angiotensin I↗
PubMed1984

A prospective study of functional status among community elders.

A six-year prospective study provides estimates of functional status (independent, dependent, nursing home resident, or deceased) according to age, gender, and previous functional status for Caucasian elders initially living in the community. Half the cohort had sustained independence for the six years; of those dependent at the beginning, one-fourth to one-third regained independent function within 15 months, and one-fifth regained self-sufficiency within five years.

Activities of Daily Living↗
PubMed1984

Ca2+-transport in skeletal muscle sarcoplasmic reticulum of the chronically diabetic rat.

Ca2+-transport in fast skeletal muscle sarcoplasmic reticulum preparations was studied in experimentally-induced diabetic rats 90 days after treatment. A significant decrease in ATP-dependent oxalate facilitated Ca2+-uptake was observed in these animals at all free Ca2+ concentrations tested (0.1-2.0 microM). A concomitant elevation in the levels of both free carnitine and long-chain acylcarnitine was also found. These observations paralleled results obtained in diabetic rat heart sarcoplasmic reticulum preparations and suggest a generalized pathophysiological mechanism affecting muscle tissue function in the diabetic animal.

Animals↗
PubMed1984

Antineoplastic admixture service in a tertiary-care hospital.

The rationale and decision-making processes involved in the development and implementation of an antineoplastic admixture service in a 1027-bed teaching hospital are described. Because of concerns expressed by nurses about the potential health hazards of handling antineoplastic drug products, the department of pharmacy was asked to prepare all injectable antineoplastic agents within the institution. At the time of the request, the pharmacy department operated 12 decentralized pharmacies and one central pharmacy; no i.v. admixture services were provided, except for total parenteral nutrient solutions. In developing the service, the pharmacy department considered the advantages and disadvantages of (1) a centralized versus decentralized organization, (2) various physical facilities, and (3) various staffing patterns. An ad hoc committee of the P & T committee was formed to develop multidisciplinary guidelines for the appropriate handling of these products. A centralized service open from 0800 to 1600 daily was established. A supervisor was hired to train and manage the rotation of the entire pharmacy staff through the area. A vertical laminar-airflow biologic safety cabinet and exhaust adapter were purchased, and policies and procedures for handling the antineoplastic agents were developed for all involved personnel. Since opening in July 1983, the antineoplastic admixture service has been positively received by health-care providers in this institution, and no major problems have been associated with the program.

Antineoplastic Agents↗