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Biomedical subjects

H A Feldman

Publications and source records attributed to H A Feldman.

At least 109 records · Page 6Linked to original sources
PubMed1984

Effect on ventilation of change to the upright posture in newborn infants.

We have investigated the effect of postural change on tidal volume (VT), inspiratory (TI) and expiratory (TE) duration, minute ventilation (VI), and end-tidal PCO2 in a group of 11 healthy full-term sleeping infants, 2-4 days of age. During tilts from the supine to upright posture, the average volume increase was 4.3 +/- 4.4 (SD) ml or 1.2 ml/kg in the maneuvers unassociated with sighs. In the 20% of tilts in which sighs occurred, the average volume change was slightly higher. Transition from supine to upright posture resulted in statistically significant increases in VT (6.45 +/- 0.06 to 6.72 +/- 0.06 ml/kg), TI (554 +/- 7 to 604 +/- 7 ms), and TE (629 +/- 12 to 777 +/- 14 ms), and decrease in VI (328 +/- 5 to 288 +/- 4 ml X kg-1 X min-1) (all means +/- SE, P less than 0.0005). Return to supine position resulted in statistically significant changes in the opposite direction. Tilting to the upright posture brought about a small (0.4 +/- 0.1 Torr, means +/- SE) but consistent statistically significant increase in end-tidal PCO2, which persisted through the first minute when the infant was returned to the supine position. The expiratory prolongation observed with tilting appears to minimize changes in end-expiratory lung volume, obviating the need for an effective compensatory muscle response to defend ventilation. Thus it appears that infants, in contrast to adults, adopt a breathing strategy to limit the extent of change in absolute lung volume, rather than to defend ventilation at increased lung volume.

Carbon Dioxide↗
PubMed1983

The PM distribution: a model for interpreting LD isoenzyme patterns.

We present a method for inferring from the lactate dehydrogenase (LD) isoenzyme pattern in serum or interstitial fluid the estimated distribution of a cellular parameter PM in the cell population from which LD was released. PM is defined as the fraction of M monomer (one of two gene products which may serve as subunits of the LD tetramer) available in a particular cell. The distribution of PM represents a more fundamental characterization of cellular biochemistry than the serum LD pattern. We apply the method to LD patterns from the literature and illustrate the advantage of this approach over simple inspection or piece-by-piece statistical analysis of LD patterns.

Animals↗
PubMed1983

Statistical limits in Scatchard analysis.

The Scatchard graph for estimating molecular receptor capacity was recently criticized for its subjectivity, by means of several examples in which graphical methods yielded meaningless estimates of receptor capacity. We applied mathematical binding models and statistical estimation to the same examples and derived quantitative measures of the uncertainty in receptor capacity. The uncertainty was within such bounds that an approximate picture of the nature and number of sites was recoverable.

Animals↗
PubMed1983

The 3/4 mass exponent for energy metabolism is not a statistical artifact.

The scaling law eta = alpha Mb is used to model basal energy metabolism (eta) in terms of body mass (M). The exponent b = 3/4 has commonly been applied to either inter-specific or intra-specific variation of body mass (the 'Brody-Kleiber law'). Heusner recently demonstrated that the exponent 2/3 provided a better description of intra-specific variation in a set of animal data from the literature and dismissed the value 3/4 as a 'statistical artifact.' Using the same data, we recast the statistical analysis in mathematically equivalent form and show that 3/4 nonetheless emerges as a precise numerical estimate of the mass exponent for inter-specific variation. We relate this finding to the theory of elastic similarity and demonstrate that there is both experimental and theoretical justification for the use of both exponents in describing the variation of basal energy metabolism among animals of different size and species.

Energy Metabolism↗
PubMed1983

Lactate dehydrogenase isoenzymes in hamster lung lavage fluid after lung injury.

Lactate Dehydrogenase Isoenzymes in Hamster Lung Lavage Fluid after Lung Injury. Beck, B. D., Gerson, B., Feldman, H. A., and Brain, J. D. (1983). Toxicol. Appl. Pharmacol. 71, 59-71. Lactate dehydrogenase (LD) levels and isoenzyme patterns were determined in the cell-free supernatant fractions of lung lavage fluid from hamsters exposed to alpha-quartz, iron oxide, Triton X-100, 100% O2, or 200 ppm SO2. The isoenzyme patterns were compared to those derived from hamster lung homogenates, serum, polymorphonuclear neutrophils (PMNs), pulmonary macrophages, and red blood cells. The isoenzyme patterns from alpha-quartz- and iron oxide-exposed animals resembled each other and were similar to that of PMNs. In contrast, the pattern seen after Triton X-100 exposure was similar to those of whole lung homogenates and of red blood cells. A 96-hr exposure to 100% O2 yielded an LD isoenzyme pattern in lung lavage fluid similar to that of serum. Exposure to SO2 did not alter LD levels, showing that upper airways damage is not reflected by changes in LD in lung lavage fluid. We conclude that LD isoenzyme patterns of lung lavage fluid can be used to differentiate among types of pulmonary injury and may help identify the sites of injury.

Animals↗
PubMed1982

Fenoprofen nephropathy: lipoid nephrosis and interstitial nephritis. A possible T-lymphocyte disorder.

Five patients are presented, each of whom had an acute idiosyncratic reaction to fenoprofen calcium (Nalfon) characterized by acute renal failure and marked proteinuria. Renal pathology was similar in all patients. Light microscopy revealed marked lymphocytic inflammatory infiltrates and normal glomeruli. Immunofluorescent staining was minimal or absent. Electron microscopy showed fusion of podocytes in otherwise normal glomeruli. Two patients were studied using T-cell and B-cell specific fluorescent staining, which revealed that the interstitial infiltrates were composed exclusively of T-lymphocytes. This finding is considered in relation to prior experimental and theoretic work. It is suggested that the various clinical and pathologic findings in fenoprofen nephropathy are all manifestations of a disordered cell-mediated immunity.

Acute Kidney Injury↗
PubMed1980

IgA proteases of two distinct specificities are released by Neisseria meningitidis.

Strains of Neisseria meningitidis produce two distinct extracellular IgA proteases that cleave the human IgA1 heavy chain at different points within the hinge region. Type 1 protease cleaves the prolyl-seryl peptide bond at position 237-238; type type 2 protease cleaves the prolyl-threonyl bond two residues amino terminal to that bond attacked by type 1 enzyme. Each meningococcal isolate elaborates only one of these two enzymes, and the type of protease produced correlates with certain serogroups: group A yielding only type 1, and groups X and Y only type 2 enzyme. In addition, analysis of amino acid sequences of human alpha-chain proteins reveals that the repeating octapeptide characteristic of the IgA1 hinge region is actually triplicated.

Amino Acid Sequence↗
PubMed1980

Identification of the activator system for antibody to Toxoplasma as the classical complement pathway.

In view of the many recent advances in our understanding of the composition and function of the complement system, it was decided to apply this newer knowledge to an investigation of the heat-labile activator required for the action of antibody to Toxoplasma gondii in the neutralization and dye tests. With use of antibody-coated toxoplasma trophozoites in a diluent of 0.2% gelatin in 0.85% NaCl and alkaline methylene blue as indicator, various component-deficient sera were added to activate the antibody on the protozoan membranes. It was determined that the classical complement system is required for antibody activity and that the properdin system plays no role in the reaction. Human sera genetically deficient in C5, C6, C7, and C8 were shown to be inactive as activators of antibody to Toxoplasma. The addition of specific missing components immediately restored full activity to the deficient sera.

Animals↗
PubMed1980

Peritonitis in chronic peritoneal dialysis patients.

The incidence, etiology and management of peritoneal infection were evaluated in a chronic peritoneal dialysis population at a private community referral hospital. An initial incidence of peritonitis of 10.8% in early 1976 was reduced to a rate of 0.19% in the latter half of 1978. Factors associated with this decline were: establishment of a separate peritoneal dialysis unit; strict adherence to aseptic technique; and the replacement of manual procedures with automated equipment. Preliminary results suggested also that antibiotic therapy of asymptomatic patients with culture-positive dialysis return may be an additional effective method for the prevention and control of peritonitis in this patient population.

Anti-Bacterial Agents↗
PubMed1979

Longitudinal study of career choices of a SUNY-Upstate cohort of medical students.

A SUNY-Upstate cohort was observed during the four-year matriculation (1974--1978) of the students for changes in their career choices. Medical school exposure seemed to increase students' interest in all major specialties, with the exception of family practice for which there was an overall 3% decrease. Internship and residency appointments accepted indicated that 75% entered primary care specialties, 8% more than the national average for 1978.

Adult↗
PubMed1979

Diabetic nephropathy as the mode of presentation of diabetes mellitus.

Diabetic nephropathy have only rarely been described in patients who have minimal or no glucose intolerance. We herein report the case of a 59-yr-old man who presented with nephrotic syndrome and minimal glucose intolerance whose renal biopsy showed the nodular (Kimmelsteil-Wilson) and diffuse glomerulosclerosis lesions characteristic of diabetes. We critically review the literature on this subject, pointing out the pitfalls in diagnosis and establishing strict criteria for the diagnosis of diabetic nephropathy in patients wihout overt clinical diabetes.

Basement Membrane↗
PubMed1979

Low density lipoprotein metabolism in type IV and type V hyperlipoproteinemia.

Low density lipoproteins (LDL) are thought to arise largely from degradation of triglyceride-rich very-low-density lipoproteins (VLDL). LDL kinetics in patients with Type IV and Type V hyperlipoproteinmia were studied and compared with normal subjects. LDL labeled in the protein moiety with 125I was used as a tracer. There was no significant difference in LDL turnover between the three groups, suggesting that a catabolic defect in VLDL degradation to LDL may exist in both Type IV and Type V hyperlipoproteinemia.

Adult↗