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Biomedical subjects

R C Webb

Publications and source records attributed to R C Webb.

At least 199 records · Page 11Linked to original sources
PubMed1979

Effects of sensorimotor training on intellectual and adaptive skills of profoundly retarded adults.

Effects of sensorimotor training on intelligence and adaptive skills of profoundly retarded young adult residents of a state institution were investigated during a 6-month intensive training program. Comparison of pre- and posttraining test scores showed that the training group made significant gains in awareness (p less than .01) and gross-motor skills (p less than .001) as well as in intellectual (p less than .02) and adaptive skills (p less than .01). No significant gains in fine-motor and imitation skills were found nor were significant changes observed in the attention (control) group. Results were interpreted in terms of sensorimotor-training integration patterns, and they substantiated previous findings that gross-motor functioning and adaptive skills improve with sensorimotor training done in the living unit.

Adolescent↗
PubMed1978

Mechanism of membrane stabilization by calcium in vascular smooth muscle.

In this study we observed relaxation in helical strips of rat tail artery in response to high concentrations of calcium after contraction induced by 10(-7) g/ml norepinephrine. This action of calcium on vascular smooth muscle contraction is referred to as the "membrane-stabilizing effect" of calcium. The current study demonstrates that changes caused by many of the variables that alter this relaxation induced by calcium parallel changes in relaxation in response to potassium; both are attenuated by ouabain, low sodium, reduced temperature, and low potassium. Relaxation produced by manganese is not similarly affected. Because potassium has been shown to cause relaxation of vascular smooth muscle by increasing the activity of sodium-potassium ATPase, we conclude that the relaxation produced by high concentrations of calcium is dependent on the activity of sodium-potassium ATPase; that produced by manganese is not.

Animals↗
PubMed1978

Role of cyclic AMP in rat aortic microsomal phosphorylation and calcium uptake.

The role of adenosine 3',5'-monophosphate (cyclic AMP)-dependent membrane phosphorylation in the regulation of microsomal calcium transport in rat aortic smooth muscle was studied. Cyclic AMP-dependent protein kinase augmented the phosphorylation of serine residues in a microsomal protein component with a molecular weight of about 44,000 (determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis) and the majority of 32P incorporation was in serine residue(s). The phosphorylated protein had stability characteristics of a phosphoester. The phosphorylated substrate was not extracted from the trichloroacetic acid (TCA) precipitate with organic solvents or by suspension in hot TCA; and the demonstrated hydroxylamine insensitivity suggested that the substrate was not lipid or nucleic acid. Intrinsic phosphoprotein phosphatase cleaved the labeled phosphate from the cyclic AMP-stimulated microsomes in the first 5 min of incubation. Microsomes phosphorylated in the presence of 1 micron cyclic AMP or 1 micron cyclic AMP plus 0.1 mg/ml protein kinase exhibited enhanced calcium uptake. We suggest that reversible phosphorylation of microsomal membranes may play an important role in the regulation of aortic microsomal calcium transport by cyclic AMP.

Animals↗
PubMed1978

Potassium-induced relaxation as an indicator of Na+-K+ ATPase activity in vascular smooth muscle.

Helical strips of rat tail artery were observed to relax in response to potassium after contraction induced by 10(-7) g/ml norepinephrine in potassium-free solution. After several minutes of relaxation, the strips showed an abrupt redevelopment of tension. The amplitude of the potassium-induced relaxation was employed as an index of the activity of the electrogenic sodium-potassium pump and hence of the Na+-K+ ATPase. This assumption seemed justified because the observed amplitude of potassium-induced relaxation paralleled known effects of the following variables on Na+-K+ ATPase: (1) intracellular sodium concentration; (2) ouabain administration; (3) magnesium; (4) temperature, and (5) potassium concentration. The relaxation that occurred in response to potassium is suggested to be due to an enhanced Na+-K+ ATPase resulting in increased electrogenic transport of sodium and potassium and, consequently, hyperpolarization. We propose that potassium-induced relaxation of rat tail artery may be used as a functional indicator of Na+-K+ ATPase activity in vascular smooth muscle.

Adenosine Triphosphatases↗
PubMed1978

Problems of infections relating to international travel.

Every year we see an increasing number of people travelling overseas. Whilst many confine their travel to Europe, South East Asia and North America, more and more people are visiting other less familiar countries where diseases not encountered in Australia occur. An awareness of the existence of such diseases and appropriate precautions against them should minimize the risk of infection.

Animals↗
PubMedDate not supplied

Novel signaling pathways contributing to vascular changes in hypertension.

In hypertension, increased peripheral resistance maintains elevated levels of arterial blood pressure. The increase in peripheral resistance results, in part, from abnormal constrictor and dilator responses and vascular remodeling. In this review, we consider four cellular signaling pathways as possible explanations for these abnormal vascular responses: (1) augmented signaling via the epidermal growth factor receptor to cause remodeling of the cerebrovasculature; (2) reduced sphingolipid signaling leading to blunted vasodilation and increased smooth muscle proliferation; (3) increased signaling via Rho/Rho kinase leading to enhanced vasoconstriction, and (4) a relative state of microtubular depolymerization favoring vasoconstriction in hypertension. These novel cell signaling pathways provide new pharmacological targets to reduce total peripheral vascular resistance in hypertension.

Angiotensin II↗
PubMedDate not supplied

Congener-specific effects of PCBs on contractions of pregnant rat uteri.

Both increased and decreased gestation lengths have been reported following exposures to polychlorinated biphenyl (PCB) mixtures and congeners. Because oscillatory uterine contractions are essential for parturition, we hypothesized that the disparate findings on gestation length may be the result of distinct PCB congener-specific actions on oscillatory uterine contractions. This study examined the acute effects of PCB congeners on isometric contractions of isolated pregnant uteri and the structure-activity relationship for individual congeners. After cumulative exposure to individual PCB congeners (0.5 microM to 150 microM), oscillatory contractions were: 1) not altered by 2,4,5,2',4',5'-hexachlorobiphenyl, 3,4,5,3',4'-pentachlorobiphenyl, or 3,4,3',4'-tetrachlorobiphenyl; 2) significantly inhibited by 4-hydroxy-2',4',6'-trichlorobiphenyl; and 3) markedly increased by 2,4,6-trichlorobiphenyl and 2,4,2',4'-tetrachlorobiphenyl, when compared to solvent controls. The uteri were more sensitive to PCB congeners with ortho-substituted light chlorination than those highly chlorinated, or those interacting with the Ah-receptor.

Analysis of Variance↗