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Biomedical subjects

J Katz

Publications and source records attributed to J Katz.

At least 451 records · Page 25Linked to original sources
PubMed1989

Studies of glycogen synthesis and the Krebs cycle by mass isotopomer analysis with [U-13C]glucose in rats.

Starved rats were infused intragastrically via indwelling duodenal cannulae with glucose at a rate of 30 mg/min/kg. The infusate contained [U-13C]glucose at an enrichment of 32 or 17%. At the end of the infusion, after 160 min, glucose and lactate were isolated from arterial and portal blood and from liver, and liver glycogen was isolated and hydrolyzed to glucose. The enrichment in glucose and lactate and the isotopomer distribution in glucose of masses from 180 to 186 were determined by gas chromatography-mass spectrometry (GC-MS). From analysis of these data we determined (a) gluconeogenesis proceeds at half the basal rate in the presence of a large infused glucose load, (b) one-quarter of the hepatic pyruvate pool is derived from nonglucose carbon, (c) half of the labeled molecules in liver glycogen are of mass 186 from the infused glucose and half are of masses 181-183, (d) the contribution of the indirect path from pyruvate when corrected for synthesis from unlabeled pyruvate ranges from 55 to 65%, (e) the rate of pyruvate carboxylase averages 90% that of citrate synthase, and (f) the rate of exchange of oxaloacetate with fumarate is about three times the rate of flux in the Krebs cycle (four times in the "forward" direction), and the enrichment in carbon 1 of oxaloacetate was 2.3 times that in carbon 4. In the Appendix a method to obtain the isotopomer distribution of newly formed glucose and glycogen glucose is described. An algorithm to correct for the contribution of natural abundance of 13C and the presence of 12C in commercial [U-13C]glucose is presented. A novel mathematical analysis to obtain the parameters of the Krebs cycle from the isotopomer distribution is developed in the Appendix. Equations to calculate the relative rates of pyruvate carboxylase (y), and the equilibration of oxaloacetate with fumarate from the isotopomer distribution are derived. Mass isotopomer analysis provides a novel and powerful tool for the study of carbohydrate metabolism and the operation of the Krebs cycle.

Animals↗
PubMed1989

A cross-reactive idiotype on anti-DNA antibodies defines a H chain determinant present almost exclusively on IgG antibodies.

We have previously reported two anti-idiotypic antibodies, 3I and 8.12, that recognize L chain determinants on anti-DNA antibodies. We have generated a new anti-idiotypic antibody, F4, that recognizes a H chain determinant on cationic anti-DNA antibodies. F4 reactivity is present in high titer in serum of approximately 60% of SLE patients and on 84 of 706 myeloma proteins. It is preferentially associated with 3I reactive L chains. Furthermore, antibodies bearing both the F4 and 3I idiotypic determinants preferentially bind DNA. Amino acid sequencing of H chains isolated from four F4-reactive myeloma proteins suggests that they derive from two currently identified VH gene families. F4 reactivity is restricted almost exclusively to Ig of the IgG isotype suggesting that F4 may recognize either a somatically mutated hypervariable region or a variable region used late in the immune response. F4, therefore, represents a new idiotypic family preferentially associated with auto-Ag specificity and having features of an Ag-driven immune response.

Amino Acid Sequence↗
PubMed1989

Liposomes as oral adjuvants.

In this brief review, emphasis was placed on the effectiveness of liposomes as carriers/vehicles of soluble antigens and as adjuvants for mucosal responses when used as oral vaccines. Evidence was provided that oral administration of antigen in liposomes resulted in an augmented mucosal response, compared to the response obtained when the oral vaccine consisted of antigen alone. Specific mucosal responses were further enhanced by the use of lipophilic MDP in the antigen/liposome vaccines. In order to better understand the properties of liposomes important for their functional activities, a rapid and reproducible method employing flow cytometry was described which can be conveniently used for the characterization of liposome preparations. Finally, evidence was presented which further supports the potential of recombinant DNA techniques in developing effective and safe oral vaccines against a variety of infectious diseases.

Adjuvants, Immunologic↗
PubMed1989

Esterase activity in second- and third-trimester amniotic fluid: an indicator of chorioamnionitis.

Accurate and rapid diagnosis of chorioamnionitis poses a major diagnostic dilemma. We previously reported that leukocyte esterase activity in amniotic fluid, as measured by dipstick assay, could be used as an aid in the diagnosis of chorioamnionitis. This study examines the effectiveness of an in vitro spectrophotometric assay of esterase activity in amniotic fluid. We define baseline levels of esterase activity in uninfected amniotic fluid and demonstrate a quantitative increase when infection is present. Fifty-seven amniotic fluid samples obtained at second- and third-trimester amniocenteses were divided into three parts, one for culture and two for a comparison of esterase activities by the dipstick and spectrophotometric methods. In this study, the spectrophotometric assay, because of its higher specificity and sensitivity in the determination of elevated esterase activity, was shown to be more reliable for predicting chorioamnionitis than either the dipstick or culture method.

Amniocentesis↗
PubMed1989

The determination of mass of metabolites with tracers.

Application of tracers in vivo for the determination of replacement and mass of bloodborne compounds at steady state is discussed. Theory and methods to determine mass with tracers (total amount of compound-tracee-within the body) for compartmental and noncompartmental systems are presented, and their limitations examined. Methods to derive mass from the specific activity curves after bolus injection or infusion of tracer are described using graphic procedures or by equations using the parameters of exponential curves. The relationship between assumed models and the interpretation of tracer data is examined. The determination of both replacement (appearance, which equals utilization at steady state) and mass of most compounds present in both extracellular and intracellular fluids (such as lactate and amino acids) requires the application of the A-V mode for tracer administration and sampling of blood. Recycling of carbon affects the determination of mass with 14C. Estimates of true mass are provided with tritium-labeled compounds, even when tritium loss is by exchange with protons or through futile cycling. Estimates of the amount (body mass) of lactate, alanine, glutamate, and proline obtained with tritium-labeled compounds are presented. Most of these masses are intracellular. The concentration of lactate in tissues equals or is greater, and that of amino acids much greater than that in plasma. Hence, the so-called "distribution space" for these compounds, calculated conventionally by dividing mass by plasma concentration, would appear to be equal to or greater than the body water of lactate, and several liters per kilogram for amino acids.

Alanine↗
PubMed1989

The interleukin concept and the periodontal diseases.

The interleukins are hormone-like substances found at sites of inflammation such as in rheumatoid arthritis and periodontal disease. The present article analyzes a hypothetical mechanism of periodontal pathogenesis, whose etiology is still unclear despite its high prevalence.

Bone Resorption↗
PubMed1989

In vivo nuclear magnetic resonance imaging of myocardial perfusion using the paramagnetic contrast agent manganese gluconate.

Previous nuclear magnetic resonance (NMR) imaging studies have indicated that coronary occlusion does not produce sufficient changes in standard tissue relaxation times to allow the detection of acute ischemia. To identify acute myocardial perfusion abnormalities, the use of the paramagnetic agent manganese gluconate combined with calcium gluconate (MnGlu/CaGlu) was investigated in canine models of acute coronary artery occlusion. In vitro studies showed that MnGlu/CaGlu was a more efficient relaxing agent than gadolinium-DTPA (relaxivity of 7.8 versus 5.1 s-1 mM-1) and demonstrated affinity for normal myocardium. The distribution of MnGlu/CaGlu as measured by manganese-54 tracer studies was proportional to myocardial blood flow in both normal and ischemic tissue. Hearts excised from dogs after coronary artery occlusion and administration of 0.035 mM/kg MnGlu/CaGlu were imaged ex vivo using a relatively spin-lattice relaxation time (T1)-weighted gradient reversal technique (repetition time [TR] 50 ms and echo time [TE] 9 ms). These images showed increased signal intensity in the normally perfused myocardium with a mean signal intensity ratio of hypoperfused to normal myocardium of 0.55 +/- 0.12 (mean +/- SD). In vivo images obtained in nine dogs after coronary artery occlusion and administration of the same dose of MnGlu/CaGlu demonstrated the region of hypoperfused myocardium in six dogs with a signal intensity ratio of hypoperfused to normal myocardium of 0.64 +/- 0.23 (p less than 0.05 versus control). When a higher dose of 0.1 mM/kg MnGlu/CaGlu was utilized and in vivo imaging was performed using a relatively spin-spin relaxation time (T2)-weighted (TR gated, TE 60 ms) spin-echo sequence in six dogs, the signal intensity of normal myocardium was decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

A nursing intervention to increase compliance in otitis media patients.

This study was conducted to evaluate two forms of a clinical nursing intervention based on the Health Belief Model (HBM) and designed to increase compliance among 59 otitis media (OM) patients (14 adults and 45 children) visiting an emergency department (ED). Subjects (adult patients or caretakers of child patients) who received an HBM clinical intervention administered by a nurse in the ED, and HBM phone intervention 2 to 4 days after the ED visit, or both interventions were much more likely than control subjects to comply with a follow-up referral appointment. Both the clinical and phone interventions were designed to increase perceived susceptibility to complications of the OM, seriousness of the complications, and benefits and costs of action. Other factors predicting compliance included subjects' unmet needs for child care, perceived seriousness of the OM, and degree of knowledge of the etiology, pathophysiology, and management of OM.

Adolescent↗
PubMed1989

The importance of age in evaluating anthropometric indices for predicting mortality.

Weights and heights were obtained on approximately 4,000 preschool-aged children in six rural villages of West Java between 1977 and 1978. Deaths occurring in the ensuing 18 months were ascertained at three-month intervals. The abilities of relative weight for height and height for age to discriminate children at greatest risk of dying were compared. Younger children (less than or equal to two years) with low height for age (less than 95% of the reference median) were at greater risk of dying than children of the same age who were not stunted. This risk declined with increasing age, and among children aged 3-5 years, those who were stunted were at no greater risk than those of normal height for age. The mortality risk associated with mild wasting (80-90% of the reference median) also declined with increasing age. However, the risk of dying among moderately to severely wasted (less than 80% of the reference median) children increased with increasing age. These results suggest that stunting, rather than wasting, puts younger children at greater risk of death, but among older children, wasting carries a greater relative mortality risk over an 18-month period.

Age Factors↗
PubMed1989

Familial gingival fibromatosis; no correlation with HLA-antigen. A family study.

Familial gingival fibromatosis is generally reported to be inherited as an autosomal dominant trait. We investigated 2 families with few siblings affected with gingival fibromatosis. No linkage between HLA antigen and the phenomenon was found. These results support the idea of the autosomal dominant nature of familial gingival fibromatosis.

Female↗
PubMed1989

Venous gas embolism: time course of residual pulmonary intravascular bubbles.

The time course of pulmonary intravascular air emboli was studied in anesthetized dogs. In one series of experiments air was infused into the right atrium at 0.10 ml.kg-1.min-1 or 0.25 ml.kg-1.min-1 for 15 min or given as a bolus injection of 2 ml/kg at 2 ml/sec. In a second series of series of experiments venous air was infused into dogs (0.25 ml.kg-1.min-1, 15 min) ventilated with 100% oxygen for 0, 30, or 210 min before the embolization. After the air infusions the animals were allowed to recover, breathing 70% nitrogen:30% oxygen. At 10-min intervals during recovery, the nitrogen was replaced with nitrous oxide (N2O) for 5 min to expand any residual pulmonary vascular bubbles. Subsequent changes in pulmonary artery pressure (Ppa) and end-tidal carbon dioxide (PETCO2) concentrations, pulmonary vascular resistance (PVR) and carbon dioxide tensions (PaCO2) as a result of the N2O challenges indicated the presence of residual gas bubbles in the pulmonary arterial system. Residual times of the pulmonary bubbles were 24.5 +/- 12.3 min (0.10 ml.kg-1.min-1 air dose), 43 +/- 10.8 min (0.25 ml.kg-1.min-1 air dose), and 17.8 +/- 2.5 min (bolus). The latter two were significantly different from each other. With 100% oxygen breathing the residual times were 19 +/- 2.2 (0 min), 22 +/- 6.7 min (30 min), and 17 +/- 4.0 (210 min). These values were reduced significantly when compared to the dogs ventilated with 30% oxygen.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗