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Biomedical subjects

P Baron

Publications and source records attributed to P Baron.

At least 109 records · Page 6Linked to original sources
PubMed1983

Effect of ouabain on the anterograde effective refractory period of accessory atrioventricular connections in children.

The anterograde effective refractory period of the accessory connection was determined before and after the administration of ouabain (0.015 mg/kg intravenously) during electrophysiologic studies in 21 patients with Wolff-Parkinson-White syndrome. The mean age (+/- standard deviation) was 10 +/- 2 years (range 1 month to 31 years). Each patient had stopped taking all cardiac drugs for more than 36 hours. Determination of the anterograde effective refractory period of the accessory connection was made using the atrial extrastimulus technique. A change in the anterograde refractory period of the accessory connection was defined as an increase or decrease of greater than 10 ms from the value before ouabain administration. The post-ouabain anterograde effective refractory period of the accessory connection increased in 2 (9%) of the 21 patients, decreased in 9 (43%) and was unchanged in 10 (48%). This study demonstrated a decrease in the anterograde effective refractory period of the accessory connection of 43% of patients with Wolff-Parkinson-White syndrome after the administration of ouabain.

Adolescent↗
PubMed1983

Developmental changes in response of dog isolated ventricular myocardium to norepinephrine.

There are maturational changes of myocardial function and response to inotropic agents. Because of incomplete myocardial sympathetic innervation, neonatal myocardium may be more sensitive to norepinephrine than is adult myocardium. We tested this hypothesis by using isolated trabecular muscle from two groups of puppies and from adult dogs. The muscles were exposed to norepinephrine at concentrations of 1 x 10(-10) to 1 x 10(-4) M, and indices of isometric and isotonic contraction were measured. Active tension and maximum rate of contraction increased in all age groups with norepinephrine. Adult dogs were more sensitive than puppies to the arrhythmogenic effect of norepinephrine. Although there was no strictly significant difference statistically, there appeared to be an age-related increase in the dose at which 50% of the maximum effect of the drug was achieved (ED50). Total contraction time, time to peak tension, and relaxation time decreased with increasing concentrations of norepinephrine in older puppies and in adults but not in newborn puppies. Thus, there are significant age-related differences in response to norepinephrine.

Journal Article↗
PubMed1981

Association of isoapolipoprotein-E3 deficiency with heterozygous familial hypercholesterolaemia: implications for lipoprotein physiology.

A prepubertal girl with both homozygous isoapolipoprotein-E3 deficiency (the genetic defect underlying type-III hyperlipoproteinaemia) and heterozygous familial hypercholesterolaemia (familial type-IIa hyperlipoproteinaemia) presented with severe hypercholesterolaemia and antecubital and popliteal planar xanthomas. She responded dramatically to clofibrate. Her mother was normolipidaemic and heterozygous for apo-E3-deficiency. Her father, an obligate apo-E3-deficient heterozygote, and his similarly affected brother died prematurely with severe hypercholesterolaemia which had been refractory to clofibrate. Her paternal grandfather, who had the same combination of disorders as the proband, also responded to clofibrate, whereas her grandmother was normolipidaemic. Hence homozygous apo-E3 deficiency may present during childhood as severe hypercholesterolaemia when combined with familial hypercholesterolaemia, suggesting that the low-density-lipoprotein receptor may represent one mechanism whereby apo-E3-deficient remnants of very-low-density lipoproteins and chylomicrons are cleared from the plasma compartment. The removal of such apo-E3-deficient remnants is especially facilitated by clofibrate.

Apolipoprotein E3↗
PubMed1981

Lymphocyte infiltration of gut epithelium in fetal and neonatal rabbits.

Lymphocytes infiltrate the epithelium of small intestinal villi of fetal rabbits as early as day 28 of gestation. They appear within the lateral spaces between the columnar absorptive cells. At this time, the epithelial cells transport compounds, such as injected horseradish peroxidase, through these intercellular spaces to the subjacent lamina propria. The possibility for in utero interaction between intraepithelial lymphocytes and antigen in swallowed amniotic fluid is discussed. There is an increase in the number of intraepithelial lymphocytes from 1 per 500 epithelial cells on day 1 to 16 per 500 epithelial cells on day 21 of postnatal life. Each segment, duodenum, jejunum and ileum, shows an increase in the number of lymphocytes during this period.

Aging↗
PubMed1980

Biomechanical analysis of the main masticatory muscles in the rabbit.

The main masticatory muscles of the Rabbit (Oryctolagus cuniculus L.) were divided into their 25 component bundles per side. 5 dry skulls were used to determine points of origin and insertion which were then projected onto 3 planes perpendicular to each other, for the establishment of a biomechanical model. By interpreting this model and by examining various mandibular movements, the bundles were classified into 16 functional groups. The findings of other biomechanical studies are contrasted with the results of the study.

Animals↗
PubMed1975

Somatostatin and serum gastrin in normal subjects and in patients with pernicious anaemia, chronic liver and renal disease.

The effects of somatostatin (growth hormone release inhibiting hormone) on basal gastrin were studied in patients suffering from pernicious anaemia and chronic renal and liver disease, and during sequential arginine/insulin-stimulated gastrin release in normal subjects. When basal gastrin concentrations were normal (10-50 pg/ml) in controls and in patients who were in renal and liver failure, somatostatin had no effect on gastrin levels. Raised basal gastrin levels in pernicious anaemia and in 2 cases of chronic renal disease, were significantly inhibited by somatostatin with a half-life (T 1/2) of 3-4 minutes. Arginine infusion caused an insignificant rise in serum gastrin which was unaffected by somatostatin, whereas insulin hypoglycaemia significantly stimulated gastrin release, which was inhibited by somatostatin.

Adult↗