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Biomedical subjects

R L Miller

Publications and source records attributed to R L Miller.

At least 325 records · Page 18Linked to original sources
PubMedDate not supplied

Acral lentiginous melanoma of the oral cavity.

Lentiginous melanomas may be classified clinicopathologically as either lentigo maligna melanomas or acral lentiginous melanomas. Lentigo maligna melanoma is generally characterized by its slow rate of growth, lateness of metastasis, and relatively good prognosis. Acral lentiginous melanoma, while demonstrating a radial growth phase which is histologically similar to that of lentigo maligna, appears biologically more similar to superficially spreading malignant melanoma once the vertical growth phase supervenes. Mucous membrane melanomas with lentiginous characteristics are likely to be aggressive lesions with a marked propensity for metastasis and a uniformly poor prognosis, much like the acral lentiginous type of melanoma. It would seem, therefore, that superficial melanomas of the oral mucous membranes with a lentiginous pattern should best be termed acral lentiginous melanomas instead of lentigo maligna melanomas so as to more accurately predict their true biologic potential. An amelanotic case is presented which we believe illustrates this point.

Aged↗
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Secretin in the rat hypothalamo-pituitary system: localization, identification and characterization.

Secretin-like immunoreactivity (SLI) has been identified and characterized in the pituitary of the rat. The concentration in the neurointermediate lobe is about 45 fold higher than the concentration of SLI observed in the anterior lobe. Transections of the pituitary stalk of the rat caused a significant depletion of SLI in the neurointermediate lobe without affecting the content in the anterior lobe. In view of the relatively high concentration of SLI reported to occur in the hypothalamus, it appears that there may be a secretinergic pathway between the brain and the neurointermediate lobe of the pituitary.

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PubMedDate not supplied

Secretin modulation of behavioral and physiological functions in the rat.

The effect of secretin on behavioral and physiological functions in the rat was investigated. Secretin injected intracerebroventricularly (ICV) significantly increased defecation and decreased novel-object approaches in rats. The peptide showed no significant effects on stereotypic behavior (gnawing, grooming and rearing), open-field locomotor activity however was significantly decreased, an effect that was probably due to a decreased propensity for the rats to initiate locomotor responses. In addition, secretin showed significant effects on respiration rate in anesthetized rats. When the peptide was injected in the lateral ventricle a decrease in respiration rate occurred, but when the brain was perfused from the lateral ventricle to the cisterna magna increases in respiration rate occurred. These data, combined with the facts that secretin and secretin receptors have been identified in the brain indicate that secretin may play a neurotransmitter or neuroregulator role in the central nervous system.

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Secretin receptors in the rat kidney: adenylate cyclase activation and renal effects.

In previous studies it has been demonstrated that pharmacological administration of secretin can alter urine output. Whether the effect is due to a direct action on kidney was investigated by examining the effect of secretin on renal output, and determining whether there were secretin receptors and a secretin sensitive adenylate cyclase in the kidney. Secretin had an antidiuretic action on kidney when administered intravenously to anesthetized hydrated rats. In addition, binding sites for (125I)-secretin, and a secretin sensitive adenylate cyclase were identified in rat kidney. Binding was saturable and reversable and was half maximally inhibited by 1 X 10(-7) M synthetic porcine secretin. Autoradiographic studies revealed a high density of secretin binding sites in the outer medulla of the kidney, a region that is composed mainly of the thick ascending limb of the loop of Henle, and is also the major site of action for the antidiuretic hormone, vasopressin. The data indicate that a functional secretin receptor system exists in kidney which may have a physiological role in regulating urine output.

Adenylyl Cyclases↗
PubMedDate not supplied

Radioimmunoassay of pyridostigmine in plasma and tissues.

A sensitive and specific radioimmunoassay is reported for the cholinergic agent, pyridostigmine. Antibodies were raised in rabbits against a conjugate of pyridostigmine and bovine serum albumin. The assay can detect as little as 2.5 ng/ml of drug directly in plasma and tissue homogenates. Structurally similar compounds and major metabolites are not recognized by the antibody. The specificity of the antibody has been confirmed by utilizing high pressure liquid chromatography. Plasma concentration-time profiles and tissue distribution of the drug were determined by this method in rat after intramuscular administration of pyridostigmine.

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