Biomedical subjects

M Dyas

Publications and source records attributed to M Dyas.

3 recordsLinked to original sources

PubMed1993

Development of chloride transport by the rat choroid plexus, in vitro.

The uptake and efflux of 36Cl in the lateral ventricle choroid plexus of 1-7-week-old rats were measured to determine if Cl transport changed with age and if such transport responded to inhibitors of CSF secretion and ion transport. The steady-state (30 min) Cl uptakes were 148 +/- 9.4 nmol.mg-1 dry weight at 1 week and 139 +/- 7.0 nmol.mg-1 dry weight at 7 weeks, (P > 0.05). The 36Cl efflux was significantly slower in 1 and 2 week plexuses compared to more mature tissues (P < 0.01) with k (rate coefficient) = 0.029 +/- 0.004 s-1, t1/2 = 24.1 +/- 3.3 s at 1 week and k = 0.041 +/- 0.003 s-1, t1/2 = 17.4 +/- 1.3 s at 7 weeks. 36Cl efflux at 1 week was unaffected by acetazolamide, bumetanide and DIDS (4,4 diisothiocyanato-stilbene-2,2 disulphonic acid), however, all these drugs substantially reduced efflux from 2, 3 and 7 week choroid plexuses. In contrast, the Cl conductance blocker, DPC (diphenylamine carboxylate) at 10(-4) M reduced 36Cl efflux from both 1 and 7 week tissues by 43% and 39%, respectively. These findings suggest that some transport systems responsible for movement of Cl out of the epithelium are either absent or less functional in the immature rat choroid plexus and may account for the relatively low level of CSF secretion in younger animals. The unidirectional efflux of 36Cl, J, was calculated for 1 week and adult rats, as a function of the choroid plexus volume to surface area ratio (V/A).(ABSTRACT TRUNCATED AT 250 WORDS)

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

PubMed1992

Ethacrynic acid and furosemide alter Cl, K, and Na distribution between blood, choroid plexus, CSF, and brain.

Can loop diuretics like ethacrynic acid and furosemide, when administered intravenously, significantly alter ion transport and fluid dynamics in CNS? To shed light on this unresolved issue, we tested the ability of these agents to effect redistribution of Na, K and Cl in adult rat brain. Cl penetration into various CNS regions was assessed as the volume of distribution, i.e., uptake, of 36Cl from blood. Ethacrynic acid and furosemide (50 mg/kg IV) reduced by 20-30% the rate of permeation of 36Cl across the blood-CSF barrier, and they elevated [K] and [Cl] in choroid plexus (CP) by 15-25%. The loop diuretic-induced buildup of K and Cl in CP (lateral and 4th ventricle) was likely a reflection of decreased movement of these ions across the apical membrane into CSF. 36Cl activity in parietal cortex and pons-medulla decreased in treatment with furosemide and ethacrynic acid, due to slowing of Cl transport across blood-brain and/or blood-CSF barriers. Our inhibitory findings in intact rats are consistent with those from previous in vitro experiments demonstrating diminution by loop diuretics of Na, K and Cl transport across isolated CP membranes.

Acetazolamide↗

PubMed1990

Behavior modification in pediatric hemodialysis.

This article reports the results of a behavior modification approach for managing disruptive and noncompliant behaviors in four male hemodialysis patients ranging in age from 10 to 16 years. Each patient demonstrated some improvement in either behavior or health status during the intervention and 76.7% of available token reinforcers were earned. The intervention was inexpensive and well-accepted by the patients, families, and staff. Guidelines for the planning, implementation, and evaluation of such interventions are presented.

Adolescent↗