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Biomedical subjects

J Katz

Publications and source records attributed to J Katz.

At least 307 records · Page 17Linked to original sources
PubMed1994

Body position does not affect the hemodynamic response to venous air embolism in dogs.

Current therapy for massive venous air embolism (VAE) includes the use of the left lateral recumbent (LLR) position. This recommendation is based on animal studies, conducted 50 yr ago, which looked primarily at survival. Little is known, however, about the concomitant hemodynamic response after VAE in various body positions. The purpose of this study was to investigate the hemodynamic and cardiovascular changes in various body positions after VAE. Twenty-two mechanically ventilated supine mongrel dogs received a venous air infusion of 2.5 mL/kg at a rate of 5 mL/s. One minute after the infusion, 100% oxygen ventilation was commenced and the body position of the dogs was changed to either the LLR (n = 6), the LLR with the head 10 degrees down (LLR-10 degrees; n = 6) or the right lateral recumbent (RLR; n = 5) position. Five dogs were maintained in the supine position (SUP; n = 5). One dog died in every group except in the SUP group, where all the dogs recovered. There were no significant differences among the various body positions in terms of heart rate, mean arterial pressure, pulmonary artery pressure, central venous pressure, left ventricular end-diastolic pressure, or cardiac output. The acute hemodynamic changes occurring during the first 5-15 min after VAE recovered to 80% of control within 60 min. Our data suggest that body repositioning does not influence the cardiovascular response to VAE. Specifically, our data do not support the recommendation of repositioning into the LLR position for the treatment of VAE.

Animals↗
PubMed1994

Reflections on unethical experiments and the beginnings of bioethics in the United States.

The author offers personal reflections on the development of research ethics in the United States, primarily during the 1960s. He explores the efforts of the pioneers in the field of human experimentation ethics to raise and discuss issues such as the value conflict between the acquisition of knowledge and respect for the autonomy of research subjects and the crucial importance of disclosure in the informed consent process.

Bioethics↗
PubMed1994

Minimizing projected liability under FAS No. 106.

Although the Statement of Financial Accounting Standards No. 106: Employers' Accounting for Postretirement Benefits Other Than Pensions requires that the anticipated cost of providing medical services to an employee following his or her retirement be accrued while the individual is employed, hospitals that provide their retirees with medical services are in a position to minimize their projected liability. The values of actual expenditures to be incurred for providing medical services should be valued in a manner consistent with the recording of other expenditures.

Accounting↗
PubMed1994

Dexfenfluramine and serotonin neurotoxicity: further preclinical evidence that clinical caution is indicated.

Dexfenfluramine, a drug used as an appetite suppressant in Europe, is currently under evaluation for approval in the United States. Studies in animals indicate that dexfenfluramine damages brain serotonin neurons, but have been challenged by some because of questions regarding their relevance to humans. The present studies were designed to address the three most salient questions regarding the applicability of preclinical dexfenfluramine neurotoxicity data to humans. Specifically, the present studies sought to determine: 1) whether dexfenfluramine's effects on brain serotonin neurons are transient and related to its therapeutic actions; 2) whether the p.o. route of administration affords protection against dexfenfluramine neurotoxicity; and 3) whether the mouse, an animal thought to best approximate the human with regard to dexfenfluramine metabolism, is sensitive to dexfenfluramine's neurotoxic action. Results from the present study indicate that monkeys continue to show large serotonergic deficits as long as 12 to 17 months after dexfenfluramine treatment, suggesting that dexfenfluramine's effects in nonhuman primates are persistent and unlikely to be related to its therapeutic actions. Furthermore, the present results indicate that the p.o. route of administration affords little or no protection against dexfenfluramine neurotoxicity. Finally, mice, like all other animals tested to date, were found to be susceptible to dexfenfluramine neurotoxicity. Taken together, these findings indicate that concern over possible dexfenfluramine neurotoxicity in humans is warranted, and that physicians and patients alike need to be aware of dexfenfluramine's toxic potential toward brain serotonin neurons.

Animals↗
PubMed1994

Effect of interleukin-2 on salivary gland morphology and function in mice.

C57BL mice were injected intraperitoneally with 300,000 Cetus units/day of human recombinant interleukin-2 (rIL-2) for 2, 4, and 5 days to study its effect on salivary gland function and morphology. The pilocarpine-stimulated parotid salivary flow was collected via cannulation of the glandular duct. Total salivary protein was assayed spectrophotometrically, salivary electrolytes were determined by atomic absorption, and glandular lymphoid cell infiltration was evaluated histologically. After 5 days of rIL-2 administration salivary output and total salivary protein concentrations were reduced significantly. Similar changes, albeit to a lesser extent, were observed following 2 and 4 days of rIL-2 treatment. Increased lymphoid infiltration of the salivary glands was observed, and was directly related to the duration of rIL-2 administration. The effect of the lymphokine on the parotid gland gradually dwindled after cessation of treatment: 4 days posttreatment this salivary gland showed signs of recovery, which at 10 days proved to be complete. The possible use of this animal model in the study of lymphocyte-induced salivary gland diseases is discussed.

Animals↗
PubMed1994

Fractal analysis of pulmonary arteries: the fractal dimension is lower in pulmonary hypertension.

We analyzed the spatial structure of contact radiographs of barium-filled pulmonary arteries of rats raised in room air and in two environments that induce pulmonary arterial hypertension (PAH)--hypoxia and hyperoxia. We found that the spatial structure of the pulmonary arteries was fractal in both the control and the hypertensive lungs. The fractal dimension of the pulmonary arteries of the control lungs was 1.62 +/- 0.01 (mean +/- SEM), which is greater than that of both the hypoxic lungs 1.50 +/- 0.03 (p < 0.01) and the hyperoxic lungs 1.44 +/- 0.01 (p < 0.01). There was no significant difference between the hypoxic and hyperoxic lungs. The fractal dimension may be a useful clinical index to quantify pathologic changes in the pulmonary arterial tree.

Animals↗
PubMed1994

Appropriate statistical methods to account for similarities in binary outcomes between fellow eyes.

PURPOSE: Many ocular measurements are more alike between fellow eyes than between eyes from different individuals. To make appropriate inferences using data from both eyes rather than the best or worst eye, statistical methods that account for the association between fellow eyes must be used. METHODS: Marginal and conditional regression models account for the association between fellow eyes in different ways. The authors compare and contrast these methods using data from a series of patients with retinitis pigmentosa in whom the primary object is to identify risk factors, some of which are subject specific and some of which are eye specific, for visual acuity loss (as a binary outcome) among affected subjects. RESULTS: Odds ratios for age, gender, presence of posterior subcapsular cataract, and genetic type of retinitis pigmentosa obtained from the marginal model were all larger than those from the conditional model. Familial aggregation of visual acuity loss was statistically significant in the marginal, but not in the conditional, model. CONCLUSIONS: The estimates and interpretation of the association between an ocular outcome and risk factors can differ significantly between these two approaches. The choice of model depends on the scientific questions of interest rather than on statistical considerations. Computer programs are available for implementing both models.

Baltimore↗
PubMed1994

Introduction to coronary arteriography.

Coronary arteriography is the most reliable means of investigating and quantitating the severity of coronary artery occlusive disease. Although the procedure is no longer performed exclusively by radiologists, their input into its interpretation is valued. Furthermore, current and future advances in nonangiographic means of demonstrating coronary artery morphology, including magnetic resonance angiography, reinforce the need for radiologists to remain familiar with techniques for the performance of coronary arteriography, the basic anatomy of the coronary artery tree, and patterns of congenital and acquired coronary artery disease.

Cardiac Catheterization↗
PubMed1994

Angiocardiography in the diagnosis of congenital heart disease.

Despite tremendous advances in cardiac imaging technology, there still exists an important role for the performance of angiocardiography in children with congenital heart disease. This article contains an outline describing the facilities in which the examinations are performed, how the examination is performed, and, most importantly, the basic tenets of interpretation.

Age Factors↗
PubMed1993

Isotopomer studies of gluconeogenesis and the Krebs cycle with 13C-labeled lactate.

Fasted rats were intragastrically infused with either [2,3-13C]lactate or [1,2,3-13C]lactate. The infusate also contained 14C-labeled lactate and [3-3H]glucose. Glucose, alanine, glutamate, and glutamine were isolated from liver and blood. There was near complete equilibration of lactate and alanine, and the relative specific activities and relative enrichments were the same in blood and liver. Glucose was cleaved enzymatically to lactate. The compounds were examined by gas chromatography-mass spectroscopy. From the mass isotopomer spectra of the lactate, glutamate, and glutamine and their cleavage fragments the positional isotopomer composition of these compounds was obtained. The enrichment and isotopomer pattern in the lactate from cleaved glucose represents that in phosphoenolpyruvate (PEP). When [1,2,3-13C]lactate was infused the mass isotopomer spectrum of glutamates consisted only of compounds containing either one, two, or three 13C carbons per molecule (m1, m2, and m3). There was little 13C in C-4 and C-5 of glutamate. The rate of pyruvate decarboxylation is low, and 3-4% of the acetyl-CoA flux in the Krebs cycle is contributed by lactate carbon. The major isotopomers in lactate, alanine, and PEP were m3 and m2 with 13C in C-2 and C-3. The predominant isotopomer in PEP from [2,3-13C]lactate was m2 with 13C in C-2 and C-3. There was much more of m1 isotopomer with 13C in C-3 and C-2 than the m1 isotopomer with 13C in C-1. There was very little m3, the isotopomer with 13C in all three carbons. Most of the 13C in C-3 and C-4 of glucose and C-1 of glutamate was introduced via 13CO2 fixation. From the isotopomer distribution and the rate of glucose turnover we deduced, applying the analysis described in the "Appendix," the absolute rates of gluconeogenic pathways, recycling of PEP and the Cori cycle, and flux in the Krebs cycle. The flux from oxaloacetate (OAA)-->PEP was seven times that of OAA-->citrate, and about half of PEP was recycled to pyruvate via pyruvate kinase. The mass isotopomer patterns in glutamate and glutamine were similar but differed from those of lactate and glucose. It appears that the glutamates are derived from alpha-ketoglutarate from a different Krebs cycle pool than PEP. The flux from OAA to PEP in this pool was two to three times that of OAA to citrate.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetyl Coenzyme A↗
PubMed1993

Estimation of design effects and diarrhea clustering within households and villages.

The degree to which diarrheal disease clustered within households and within villages among preschool age children was examined using data from four population-based prevalence surveys undertaken in Malawi, Zambia, Indonesia, and Nepal over the past decade. The design effect for each cluster survey was calculated using the diarrhea prevalence, the cluster sizes, and the magnitude of diarrhea clustering within the sampling unit (villages). A recently developed statistical method, alternating logistic regression, was used to estimate disease associations within households of up to nine preschool age children residing within villages of up to 589 such children. Pairwise odds ratios estimating diarrhea clustering within villages ranged from 1.03 (95% confidence interval (CI) 1.01-1.07) in Zambia to 2.19 (95% CI 1.73-2.78) in Indonesia. The design effects ranged from 2.07 (95% CI 1.26-3.19) in Zambia to 7.93 (95% CI 5.16-11.52) in Indonesia. Design effects were strongly dependent on cluster size. The design effects for clusters of size 50 would have ranged from 1.38 to 4.73. Pairwise odds ratios for diarrhea clustering within households ranged from 1.88 (95% CI 1.61-2.19) in Nepal to 10.05 (95% CI 8.46-11.94) in Indonesia. Household odds ratios were always larger than village odds ratios. The village and household pairwise odds ratios adjusted for age, the type of latrine used by the household, and presence of a market in the village were slightly higher than the unadjusted odds ratios. Alternating logistic regression provided useful estimates of disease clustering within villages and household while allowing for covariate adjustment.

Child, Preschool↗