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Biomedical subjects

H Stark

Publications and source records attributed to H Stark.

At least 181 records · Page 10Linked to original sources
PubMed1983

Modulation of acid secretion from enriched guinea pig parietal cells by opioid receptors.

Membrane fragments of isolated cells from guinea pig gastric mucosa, enriched to 65% parietal cells, bind with high affinity the opioid peptide 3H-D-Ala2-D-Leu5-enkephalin (3H-DADLE). Binding was saturable and reversible. Scatchard analysis revealed a second binding site with low affinity but high capacity. Acid secretion by isolated, enriched parietal cells was determined by means of 14C-aminopyrine uptake. Basal acid secretion was not influenced by DADLE but that stimulated by histamine was further augmented by the enkephalin analog. This potentiating effect was prevented by the opioid antagonist naloxone. The present data provide for the first time evidence that gastric acid secretion is modulated by an opioid mechanism probably located on the parietal cell.

Animals↗
PubMed1983

Pathophysiologic studies in idiopathic hypercalciuria presenting in childhood.

Idiopathic hypercalciuria (IH) was diagnosed in 11 children aged 5 3/12 to 10 6/12. Eight patients investigated 1-12 years later still had hypercalciuria. When compared to a control group of 10 healthy children, 5 patients demonstrated an excessive rise in urinary Ca excretion following an oral Ca load. These patients also demonstrated low urinary cAMP, normal serum iPTH and high normal iTCT levels. The remaining 3 patients responded normally to Ca loading, but otherwise showed similar metabolic findings as the above group. These findings suggest a hyperabsorptive mechanism for all our patients. The finding of relatively low values for TmP/GFR in most IH patients further suggests that here, as in many adult patients, this may be the primary pathogenic mechanism, causing low serum P, increased synthesis of 1,25 dihydroxyvitamin D and, thus, absorption of Ca. We believe this represents a physiologic variant state and not a disease state.

Adolescent↗
PubMed1983

Renal anomalies in neonates with spontaneous pneumothorax - incidence and evaluation.

Over a seven year period 23 neonates with spontaneous pneumothorax and/or pneumomediastinum (SPP) were diagnosed in 24,739 live birth infants (0.09 percent). Of these, eight (35 percent) had renal anomalies. Three showed severe renal dysfunction and typical Potter facies and died within 34 hours. Their lungs were shown to be hypoplastic with a reduced lung weight: body weight ratio or a low radial alveolar count. One patient had left hypoplastic and right polycystic kidneys. Four patients with obstructive uropathies did not show the typical facies, and SPP was the only sign leading to their early diagnosis and therapy. We conclude that nephrologic evaluation is indicated in newborns with unexplained SPP and recommend abdominal ultrasound and if indicated renal scan and/or intravenous pyelography as part of the initial evaluation.

Female↗
PubMed1982

Uptake of 6-fluoro-5-hydroxytryptamine and 4,6-difluoro-5-hydroxytryptamine into releasable and non-releasable compartments of human platelets.

1 The ring-fluorinated compounds, 6-fluoro-5-hydroxytryptamine and 4,6-difluoro-5-hydroxytryptamine, are sterically similar to 5-hydroxytryptamine (5-HT) but have pKaS for their 5-hydroxyl groups (9.7 and 8.0 respectively) which are lower than that of 5-HT. 2 The rates at which [3H]-5-HT, [3H]-6-fluoro-5-HT, and [3H]-4,6-difluoro-5-HT entered the releasable (vesicular) and non-releasable compartments of washed human platelets during a 1 min incubation period at 37 degrees C were similar. These portions of the uptake process therefore appears to be relatively independent of the pKa of the 5-hydroxyl group. 3 The [3H]-4,6-difluoro-5-HT was unique since material accumulated in the non-releasable compartment during uptake did not migrate into the vesicular compartment under appropriate incubation conditions. 4 The data suggest that the zwitterionic form of 5-HT is not the transported species, but that the electronic configuration about the 5-hydroxyl group may be critical for translocation from a non-releasable to a releasable compartment.

Blood Platelets↗
PubMed1981

Anomalous compartmentation of 5-hydroxytryptamine in intact human platelets.

1 The movement of radiolabelled 5-hydroxytryptamine (5-HT) between the extracellular medium, the thrombin-releasable (vesicular) compartment, and a non-thrombin-releasable compartment has been investigated in washed human platelets. 2 Appreciable amounts of extracellular 5-HT can accumulate in a non-releasable compartment. Depending on the incubation conditions and the amount of 5-HT already present inside the cell, non-releasable 5-HT can either remain non-releasable or rapidly migrate into the vesicular compartment. 3 Measurable amounts of vesicular 5-HT can also enter a non-releasable compartment. However, vesicular 5-HT which becomes non-releasable does not appear to mix with 5-HT becoming non-releasable following uptake from the extracellular medium. 4 Extracellular 5-HT can be added to vesicles and to the non-releasable compartment in the presence of appreciable quantities of 5-HT already in one or both compartments. 5 The vesicular and non-releasable compartments appear to accumulate 5-HT independently of one another. Furthermore, most vesicular accumulation of 5-HT occurs from the extracellular medium, rather than by translocation of non-releasable 5-HT into the vesicular compartment.

Biological Transport↗
PubMed1981

Applicability of models for carrier-mediated serotonin transport to pools of serotonin in intact human platelets.

Intact human platelets can accumulate serotonin (5HT) in compartments which are vesicular (thrombin-releasable) or extra-vesicular (non-thrombin-releasable). 1. The net accumulation of extracellular 5HT in either compartment is not coupled in a reciprocal fashion to the presence of appropriate sodium gradients across the cell plasma membrane, and 5HT already present in either compartment is not removed when trans-membrane sodium gradients are abolished or reversed. 2. Net counter-transport of 5HT in either compartment is not detectable. 3. The data are not consistent with transport models such as that for glucose in which appropriate sodium gradients produce gradients of a co-transported molecule, or with models in which counter-transport can occur.

Biological Transport↗
PubMed1981

Utility of ten-second uptake periods for kinetic studies of serotonin uptake by intact platelets.

When washed human platelets accumulate serotonin (5HT), it is possible with the use of formaldehyde fixative to measure uptake over periods as short as 10 seconds. To evaluate the utility of these short times for kinetic studies of 5HT uptake, we have examined the accuracy with which the 10 second uptake rate reflects changes in the extracellular 5HT concentration. The amount of 5HT taken up over a 10 second period appears to be determined by the concentration of 5HT present in the extracellular medium during that time period, and the uptake rate can change rapidly following sudden changes in the extracellular 5HT concentration. However, the extent of inhibition of 5HT uptake in the presence of imipramine of extracellular 5HT concentrations greater than 10-5M is somewhat different depending on whether the 5HT is allowed to accumulate for a 10-second or a 5- or 10-minute uptake period. A 10-second uptake period thus appears to be useful for kinetic studies of initial 5HT uptake velocities under normal conditions, but under inhibitory conditions may give results differing from those obtained with minute-long periods.

Blood Platelets↗
PubMed1980

[The influence of hexoprenalinsulfate aerosol on the ciliary wave frequency of the respiratory epithelium (author's transl)].

A report is given on the possible influence of hexoprenalinsulfate on the mucociliary wave frequency of the mucous membrane of the respiratory tract. The object of investigation was native human tracheaL mucosa obtained by tracheotomies. It was shown, that there was a significant decrease in frequency just on account of the usual gas fraction of the aerosol spray. If air was used instead of the gas, hexoprenaline did not influence the ciliary wave frequency.

Aerosols↗
PubMed1980

Dissolution of cystine calculi by pelviocaliceal irrigation with D-penicillamine.

We report on a cystinuric patient in whom unilateral hydronephrosis developed as a result of massive renal stone formation owing to non-compliance of systemic penicillamine therapy. At operation a large number of calculi could not be removed for technical reasons. After successful in vitro dissolution of 1 calculus using a 0.5 per cent solution of D-penicillamine at pH 8.0 the same solution was used to irrigate the renal collecting system via a nephrostomy tube. After 2 months of daily irrigations, which were decreased to 2 times a week for another 2 months, all the stones appeared radiographically to have disappeared. At followup 2 years after removal of the nephrostomy tube the patient is on regular systemic therapy with no evidence of residual or recurrent stone formation.

Adolescent↗
PubMed1980

[Clinical experience with daily doses of misonidazole (author's transl)].

In this pilot study daily low doses of misonidazole (in the range of 1 to 2 g) up to cumulative doses between 7 and 19 g/m2 were used. Serum levels were analysed at different times after administration and according to several dose regimens. We related the cumulative doses to the incidence and severity of the observed peripheral neuropathies. The aim was to find an effective daily low-dose schedule of misonidazole with a clinically acceptable incidence of side effects. Some impressive clinical responses were observed.

Adult↗
PubMed1979

Persistent hyponatremia and inappropriate antidiuretic hormone secretion in children with extensive burns.

Three children aged 2 1/2 to 5 1/2 yr, with burns covering 30%--45% of body surface area, developed hyponatremia and serum hypotonicity on the 5th--6th day following the burn injury. The hyponatremia persisted for 10--15 days. During this period, all three passed inappropriately concentrated urines. One child also demonstrated marked and inappropriate thirst. All three children demonstrated persistent respiratory alkalosis, which appeared and disappeared concomitantly with the hyponatremia. There were no signs of dehydration, and plasma volumes, measured in two children, were normal to high. These children are believed to show evidence of inappropriate antidiuretic hormone (ADH) secretion. In the absence of those conditions known to produce this syndrome, it is postulated that in these children it may have resulted from prolonged pain, anxiety, and/or pyrexia.

Acidosis↗