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R Pratt

Publications and source records attributed to R Pratt.

5 recordsLinked to original sources
PubMed1992

The natriuretic peptides and their receptors.

Atrial natriuretic factor (ANF) is released from the cardiac atrium in response to stretch and acts through receptors to cause an increase in urinary flow and sodium excretion, vasodilatation, and a reduction in blood volume. Recently, two new natriuretic peptides, brain natriuretic peptide (BNP) and C-type natriuretic peptide (C-typeNP), have been isolated, and three different natriuretic peptide receptors have been identified. Two of the receptors, ANP-RGC(A) and ANP-RGC(B), mediate biologic actions. The natural ligand of ANP-RGC(A) is ANF, whereas that of ANP-RGC(B) is C-typeNP. In view of clear differences in ligand specificity and tissue distribution of these receptors, it has been proposed that ANF and its receptor, ANP-RGC(A), and C-typeNP and its receptor, ANP-RGC(B), represent two distinct natriuretic peptide regulatory systems. Whether a separate system exists that incorporates BNP awaits clarification of its natural receptor that mediates a biologic action. The third receptor, ANP-Rc, binds all three natriuretic peptides. Its messenger RNA lacks the guanylyl cyclase sequence present in the mRNA of the other natriuretic peptide receptors, suggesting that the principal function of ANP-Rc is to remove natriuretic peptides from the circulation, that is, to regulate plasma levels of the natriuretic peptides. However, ANP-Rc may also mediate a biologic effect. These findings raise several intriguing questions about the functional role of this family of natriuretic peptides.

Animals↗
PubMed1979

Role of the periaqueductal grey in vocal expression of emotion.

In 32 squirrel monkeys (Saimiri sciureus) the role of the periaqueductal grey has been investigated by combined stimulation/lesioning and by neuroanatomical experiments. The results are as follows. Firstly, periaqueductal lesions invading the laterally adjacent tegmentum abolish species-specific calls elicitable by electrical brain stimulation. This holds for stimulation sites rostral as well as caudal to this area. The only vocalizations which survive are phonations of an artificial character which can be evoked from the lateral medulla. Spontaneous vocalizations also seem to be abolished. Secondly, vocalizations elicited from the periaqueductal grey are not affected by bilateral lesions in vocalization-eliciting areas rostral to it, but are abolished by lesions in the dorsolateral pons and ventrolateral medulla. Thirdly, the periaqueductal grey receives direct projections from all vocalization-eliciting areas tested, viz. the precallosal cingulate gyrus, gyrus rectus, medial amygdata, central amygdaloid nucleus/substantia innominata, nucleus striae terminalis, dorsal hypothalamus, midline thalamus, periventricular grey, dorsolateral and ventrolateral midbrain tegmentum. Fourthly, the periaqueductal grey projects directly to the nucleus ambiguus, the site of the laryngeal motoneurones. The course of the main bulk of fibres corresponds to the lesion sites effective in abolishing periaqueductally elicited vocalizations. From these results, it was concluded that the caudal periaqueductal-lateral tegmental area is a necessary relay station for all external and internal stimuli capable of inducing species-specific calls. Its position within the stimulus-response loop seems to be on the output side, immediately above the level of motor-corrdination but below that of stimulus recognition.

Animals↗
PubMed1979

The cingular vocalization pathway in the squirrel monkey.

In 39 squirrel monkeys (Saimiri sciureus), the effects of various brain lesions on vocalizations elicited from the precallosal cingulate gyrus were tested. It was found that lesions abolishing the "cingular vocalization" completely can be traced from the stimulation site continuously down to the laryngeal motoneurons in the nucleus ambiguus. The pathway thus determined (Fig. 4) travels from the precallosal cingulate gyrus through the frontal white matter and enters the internal capsule from a dorsolateral position. The pathway then follows this structure in a medio-caudal direction down to the caudal diencephalon. Here, the effective lesions leave the corticospinal tract and ascend dorsally into the periaqueductal grey. The pathway follows this structure to its end where it sweeps lateral through the parabrachial area and then descends through the lateral pons and ventrolateral medulla to the nucleus ambiguus. In nine of the animals, in addition, the effects of bilateral anterior cingular lesions on vocalizations elicited in other brain areas were tested. It was found that the only vocalization-eliciting area which becomes ineffective after destruction of the anterior cingulate gyrus is the postero-medial orbital cortex.

Animals↗
PubMed1976

Childhood antecedents of adult obesity. Do chubby infants become obese adults?

We investigated whether obese infants tend to become obese adults. Records of subjects born between 1945 and 1955 were reviewed to select three cohorts based on weight in the first six months of age, which exceeded the 90th percentile at least once, ranged between 25th and 75th percentiles or was below 10th percentile at least once. Three hundred and sixty-six subjects, now between 20 and 30 years of age, were located and their present height and weight determined. Thirty-six per cent of those exceeding the 90th percentile as infants were overweight adults, as compared to 14 per cent of the average age and light-weight infants. A significant increase (chi square = 17.2, p less than 0.001) in adult obesity was evident when the infant exceeded the 75th percentile that was independent of his height. Social class, educational level, and parental weight all correlated with adult weight (p less than 0.001). Sex and ordinal position of birth did not. The data suggest that infant weight correlates strongly with adult weight independently of other factors considered.

Adolescent↗