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Biomedical subjects

M Feldman

Publications and source records attributed to M Feldman.

At least 217 records · Page 12Linked to original sources
PubMed1989

Gastric acid secretion, gastrin release, and gastric emptying in humans as affected by liquid meal temperature.

We investigated the effect of the temperature of a liquid meal on intragastric temperature, gastric acid secretion, gastrin release, and gastric emptying in normal human subjects. Coffee (360 mL) was infused into the stomach through a nasogastric tube at 58 (steaming hot), 37, or 4 degrees C (ice cold). Intragastric temperature, measured by an intragastric temperature sensor attached to the nasogastric tube, returned to body temperature 16.7 +/- 2.7 min after the hot meal and 23.8 +/- 1.1 min after the cold meal. Gastric acid secretion increased after hot, warm, and cold coffee but the initial temperature of the meal had no effect on gastric acid secretion. The temperature of the meal also had no effect on serum gastrin concentrations, which increased significantly after all the meals. Gastric emptying of hot, warm, or cold coffee meals was similar. These findings indicate that over a wide temperature range, the temperature of a liquid meal has little effect on gastric function in humans.

Adult↗
PubMed1989

Effects of fish oil on gastric mucosal 6-keto-PGF1 alpha synthesis and ethanol-induced injury.

Fundic mucosal content and synthesis of 6-ketoprostaglandin F1 alpha, the major prostanoid in the rat gastric mucosa, were determined after rats had ingested a diet containing 10% fish oil or 10% corn oil for 4 wk. 6-Ketoprostaglandin F1 alpha content and synthesis in rats fed a fish oil-supplemented diet were reduced significantly compared with rats receiving a corn oil-supplemented diet (P less than 0.05). However, rats receiving 10% fish oil for 8 wk sustained significantly less gastric mucosal injury after intragastric challenge with 15% and then with absolute ethanol than rats receiving 10% corn oil or regular chow for 8 wk (P less than 0.05). Thus fish oil ingestion protected the gastric mucosa even though fish oils reduced mucosal prostaglandin synthesis.

6-Ketoprostaglandin F1 alpha↗
PubMed1989

Contraception in mares heteroimmunized with pig zonae pellucidae.

Ten fertile feral mares and 6 domestic horses (4 fertile mares, 1 infertile mare, 1 gelding) were immunized with heat-solubilized pig zonae pellucidae by 4 injections equivalent to 2000 or 5000 zonae each at 2-4-week intervals and a booster injection of 20,000 zonae 6-10 months after the last of the initial inoculations. The immune response was reflected by high antibody levels as measured by an enzyme-linked immunosorbent assay (ELISA) using immobilized pig zona antigen. In-vivo inhibition of fertility occurred in 12 (86%) of the 14 fertile mares studied and persisted for a minimum of 7 months. Repeated mating of the fertile domestic mares resulted in conception when anti-pig zona antibody concentrations had decreased from initial peak absorbance ratios (greater than 1.0) to relatively lower levels (0.64 or less with one exception). An indirect immunofluorescence assay, revealed a considerably lower cross-reactive antibody titre with horse oocytes as compared to pig oocytes. Clinical, endocrinological and histological analyses of the ovaries and their function following regained fertility after immunization revealed no abnormalities. One mare remained infertile.

Animals↗
PubMed1989

Evaluation of normal erectile function with color flow Doppler sonography.

To understand better the vascular events that occur during normal erection, we used color flow Doppler sonography to examine the erectile process in seven normal subjects. The relationship of systolic/diastolic velocities and spectral waveform changes in the penile arteries was studied in response to increasing pressure within the corpora cavernosa (tumescence) before and after the intracorporal administration of drugs to induce erection. A characteristic spectral waveform pattern was identified throughout the erectile cycle, and the pattern was correlated with increasing pressure. Both systolic and diastolic velocities were elevated during the initiation of erection, at which time the pressure within the corpora cavernosa was low (11-25 mm Hg). Systolic velocities remained elevated until the last phase of erection (83-106 mm Hg). Diastolic velocity decreased as the intracorporal pressure increased from 25 to 40 mm Hg. Between 40 and 63 mm Hg, diastolic velocity approximated zero. With increasing pressure (63-83 mm Hg), diastolic flow reversed. As the corpora cavernosa approached full erection (83-105 mm Hg), both the forward systolic and reverse diastolic flow components diminished. At approximately 106 mm Hg (systolic occlusion pressure), flow ceased. Systolic/diastolic velocity and waveform phase relationships could be used to define the integrity of both the cavernosal artery inflow and the venous sinusoidal outflow occlusion mechanisms. Color flow Doppler sonography enhanced our ability to observe and quantify dynamic erectile events and provided new insights into understanding normal erectile function.

Adult↗
PubMed1988

Isolation and characterization of monoclonal antibodies against ribonuclease inhibitor.

Mouse monoclonal antibodies were generated against human ribonuclease inhibitor, an intracellular regulatory protein. A total of four antibodies were isolated, all of which were of the immunoglobulin G1 subtype. Western blot analysis of the antibodies suggested monospecificity. Based on immunoradiometric competition assays two of the antibodies were determined to be directed against the same antigenic epitope, while the other two were against a second and possibly third epitope. None of the antibodies appeared to be directed against the ribonuclease binding site of the antigen. Data is presented suggesting that ribonuclease inhibitor is present in normal human serum. The potential significance of these findings is discussed.

Animals↗
PubMed1988

The reversal of the metastatic phenotype by gene transfer.

When studying the function of MHC-restricted immune responses in controlling metastatic growth we discovered that highly metastatic clones of mouse tumours express the H-2D but lack expression of the H-2K gene of the MHC system. The de novo expression of the H-2K antigen, after H-2K gene transfection, resulted in the reversal of a metastatic to a non-metastatic phenotype. This reversal was causally related to the acquisition of H-2K-restricted immunogenic properties. Immunization with H-2K-transfected cells, after surgical removal of the local tumour, abolished or significantly reduced the growth of metastases. We subsequently observed that H-2K expression is correlated with expression of the c-fos oncogenes. Transfection of H-2K-negative cells with v-fos or c-fos genes resulted in the expression of H-2K. Our studies suggest that one of the main functions of the c-fos proto-oncogenes is control of the expression of the MHC genes. Searching for additional molecular properties which characterize the metastatic phenotype, we observed that the metastatic clones of each of our lung-metastasizing tumours expresses an fms-related oncogene. This was correlated with a membrane-bound tyrosine kinase, which has the properties of growth factor receptors. We examine the possibility that our fms-like gene codes for this protein kinase, which represents a receptor for a local growth factor that controls metastatic growth in the lung.

Animals↗
PubMed1988

Human mononuclear cells which produce interferon-alpha during NK(HSV-FS) assays are HLA-DR positive cells distinct from cytolytic natural killer effectors.

Human mononuclear cells were previously shown to produce interferon-alpha (IFN) during 14 hr assays using herpes simplex virus type-1 infected fibroblasts [NK(HSV-FS)]. In this study, we have compared the effectors responsible for mediating NK(HSV-FS) cytolytic activity to those which produce IFN-alpha. Both activities were found to reside in non-adherent fractions, negative for non-specific esterase-staining cells. Like cells mediating NK cytolytic activity, IFN-alpha producing cells were found in light density Percoll gradient fractions. However, although NK(HSV-FS) and IFN production were largely overlapping, peak IFN production was consistently found in fractions slightly less dense than peak NK(HSV-FS) activity. IFN production was greatly augmented in fractions enriched for dendritic cells on hypertonic metrizamide gradients. The cells which produce IFN-alpha were phenotypically distinct from cytolytic NK effector cells: they lacked the Leu-11, Leu-7 and NKH1 cell surface markers shown to be present on both NK(HSV-FS) and NK(K562) effector cells. In addition, the IFN-alpha producing cells were found to be negative for a number of other markers characteristic of T cells, B cells or macrophages but were positive for Ia and HLA. The cells which produced IFN in response to UV-inactivated HSV antigen and to HSV-infected Raji cells were also found to be Leu-11 negative, and Ia positive. We conclude that the cells which produce IFN in response to HSV are a light density, Ia positive population which are distinct from NK cytolytic effector cells and co-purify with cells bearing a dendritic morphology. These results support our earlier findings that NK(HSV-FS) activity and IFN production are independent of one another and can segregate independently in vivo.

Antibodies, Monoclonal↗
PubMed1988

Cryptococcosis of the nasopharynx in mice and rats.

An attempt to infect the upper respiratory tract of mice and rats with various bacteria and fungi by intranasally instillation was performed. Cryptococcus neoformans was the only agent to invade the tissue. The infection was limited to the nasopharynx, a phenomenon which probably indicates the presence of a specific chemotaxis or receptor.

Animals↗
PubMed1988

Effect of placebo on meal-stimulated gastric acid secretion and serum gastrin concentration. Studies in healthy volunteers and duodenal ulcer patients.

The effect of placebos on gastric acid secretion in humans is unknown, even though placebo therapy is relatively effective in ulcer patients. Therefore, we evaluated the effect of a placebo capsule on meal-stimulated gastric acid secretion and serum gastrin concentrations in 10 healthy subjects and also in 10 patients with chronic duodenal ulcer. Each subject and patient was studied twice and in random order, once with placebo therapy prior to the meal and once without placebo. In either healthy subjects or duodenal ulcer patients, meal-stimulated acid secretion and serum gastrin concentrations were not significantly different with or without placebo administration. These studies demonstrate that a placebo capsule, administered by a physician just prior to a meal, has little, if any, effect on acid secretion or gastrin release in response to the meal. Any beneficial effects of placebos in treating patients with peptic ulcer disease are probably unrelated to inhibition of meal-stimulated gastric acid secretion.

Duodenal Ulcer↗
PubMed1988

Effect of proximal gastric vagotomy on serum pepsinogen I and II concentrations and acid secretion in duodenal ulcer patients.

Acid secretion and basal serum pepsinogen I and II concentrations were measured in 14 duodenal ulcer patients before and at intervals up to six years after proximal gastric vagotomy. Vagotomy led to significant and long-standing reductions in basal, vagally mediated (induced by sham feeding), and peak pentagastrin-stimulated acid secretion. Serum pepsinogen I concentrations also decreased significantly after vagotomy but to a significantly lesser extent than acid secretion. There was no correlation between serum pepsinogen I concentrations and peak acid secretion, either before or after vagotomy. Serum pepsinogen II concentrations decreased only slightly and transiently after vagotomy. Thus, proximal gastric vagotomy reduces acid hypersecretion and pepsinogen I hypersecretion, but not pepsinogen II hypersecretion, in duodenal ulcer patients.

Duodenal Ulcer↗
PubMed1988

Hemodynamic recovery during simulated ventricular tachycardia: role of adrenergic receptor activation.

Ventricular tachycardia (VT) produces a wide variety of hemodynamic outcomes. Variations in autonomic nervous system response were studied in an animal model of VT. In 18 dogs anesthetized with chloralose VT was simulated by ventricular pacing (rate 240 bpm). Dynamic changes in left ventricular (LV) function were assessed during sinus rhythm and after VT was initiated, under variable autonomic conditions: ganglionic blockade with hexamethonium (n = 5), alpha-adrenergic blockade with terazosin (n = 7; 0.3 mg/kg), and beta-adrenergic blockade with propranolol (n = 6; 2 mg/kg). Micromanometers were used to measure LV pressure, and endocardial piezo crystals assessed changes in cavity size. Sinus interval, an index of autonomic tone, was determined immediately after tachycardia was terminated. Under control conditions the onset of simulated VT was accompanied by severe hypotension, with a decline in LV systolic pressure from 113 +/- 5 to 67 +/- 4 mm Hg within 10 seconds (p less than 0.05). Subsequently, during persistent tachycardia peak LV pressure recovered to sinus values, and maximum +dP/dt exceeded sinus values by 20 seconds (2604 +/- 413 vs 2112 +/- 184 mm Hg/sec; 20 seconds for VT vs sinus rhythm). Diastolic pressures were unchanged, and sinus rate accelerated. Ganglionic blockade with hexamethonium resulted in persistent hypotension, blunted +dP/dt, no change in diastolic pressures, and failure of the sinus rate to accelerate after the tachycardia. After beta blockade there was sustained hypotension (LV systolic pressure 78 +/- 4 vs 120 +/- 5 mm Hg; 20 seconds for VT vs sinus rhythm), maximum +dP/dt was blunted, and minimum diastolic ventricular pressure rose. This was due to an upward shift in the diastolic pressure-dimension relationship associated with prolongation of the time constant of LV relaxation. The sinus interval did not change. In contrast, tachycardia during alpha blockade produced a sustained fall in peak LV pressure; however, maximum +dP/dt recovered (2194 +/- 328 vs 2154 +/- 153 mm Hg/sec; 20 seconds for VT vs sinus rhythm), minimum diastolic LV pressure remained low, and sinus rate accelerated after ventricular tachycardia. Hemodynamic recovery during ventricular tachycardia is mediated by the response of the autonomic nervous system and requires both alpha-adrenergic vasoconstriction and beta-adrenergic augmentation of contraction and relaxation.

Adrenergic alpha-Antagonists↗
PubMed1988

Effect of terbutaline, a beta 2-adrenoreceptor agonist, on gastric acid secretion and serum gastrin concentrations in humans.

Because beta-adrenoreceptor agonists inhibit gastrin-stimulated gastric acid secretion in animals, we postulated that the beta 2-adrenoreceptor agonist, terbutaline, would inhibit pentagastrin-stimulated acid secretion in humans. Moreover, we hypothesized that terbutaline might inhibit food-stimulated acid secretion, as gastrin is a major mediator of food-stimulated acid secretion. Subcutaneous terbutaline (0.25 mg) reduced acid secretion during intravenous infusion of a submaximal dose of pentagastrin by 30%-40% (p less than 0.005), even though terbutaline increased serum gastrin levels (p less than 0.05). Furthermore, subcutaneous (0.25 mg) or oral (5 mg) terbutaline, given before a homogenized steak meal was infused into the stomach, lowered mean food-stimulated acid secretion rates, despite enhanced postprandial serum gastrin concentrations. Terbutaline also increased serum gastrin concentrations in patients with Zollinger-Ellison syndrome and in vagotomized individuals. Thus, beta 2-adrenoreceptor agonists enhance gastrin release while at the same time inhibiting gastrin-stimulated acid secretion in humans.

Adult↗
PubMed1988

Gastric emptying of an indigestible solid in patients with end-stage renal disease on continuous ambulatory peritoneal dialysis.

Using radiopaque markers, we evaluated gastric emptying in 10 male patients with end-stage renal disease on continuous ambulatory peritoneal dialysis and in 15 normal men. Dialysis patients were studied twice, once without peritoneal dialysate in the abdomen (drained) and once with 2 L of dialysate in the abdomen (full). Each normal man and 9 of 10 dialysis patients, when drained, emptied all 10 markers by 6 h after a test meal. In contrast, 5 of the 10 dialysis patients, when full, had delayed emptying of radiopaque markers. Thus, continuous ambulatory dialysis may delay gastric emptying of indigestible solids.

Adult↗
PubMed1988

Relationship between Campylobacter pylori and gastritis in healthy humans after administration of placebo or indomethacin.

Endoscopic and microscopic appearances of antral and fundic mucosa were correlated with the presence or absence of Campylobacter pylori--and with plasma immunoglobulin G antibodies to that organism--in 23 healthy volunteers, 12 of whom had received indomethacin and 11 of whom had received no medication. Antral C. pylori, found in 9 of 23 biopsy specimens (3 of 11 controls, 6 of 12 indomethacin-treated patients; not significantly different), correlated strongly with histologic evidence of active superficial antral gastritis (p less than 0.005), but not with the endoscopic appearance of the antrum. In contrast to the antrum, fundic C. pylori, found in 14 of 23 biopsy specimens (61%), were frequently associated with histologically and endoscopically normal fundic mucosa. Campylobacter pylori-associated active antral gastritis occurred only in subjects whose fundus harbored this organism. Plasma immunoglobulin G antibody titers to C. pylori were highest in subjects with Campylobacter-associated antral gastritis and lowest in subjects without gastric Campylobacter. These studies suggest that healthy humans may harbor C. pylori in their proximal stomach without apparent ill effects. In some of these individuals, the organism also involves the antrum and is associated with active gastritis.

Adult↗