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Biomedical subjects

S Wray

Publications and source records attributed to S Wray.

152 records · Page 9Linked to original sources
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Quantitation of metabolites in NMR spectra from isolated tissues, using 14N spectroscopy and nitrate to determine tissue volume.

Quantification of metabolites is a goal of many biomedical NMR studies. To obtain absolute measurements of metabolite concentrations is often both difficult and time-consuming. In this paper a method for determining metabolite concentrations directly is described and validated. It is applicable to studies of amphibian muscles, and with suitable precautions, to other isolated organs and tissues. The method is based upon using 14N NMR and nitrate-containing solutions to determine what fraction (F) of the sensitive volume of the RF coil is occupied by tissue. As the concentration of nitrate is known it can be used to calibrate other 14N metabolites in the tissue. Moreover, once F is determined, it can be used to calibrate metabolites in spectra from other nuclei e.g., 31P or 31C. All that is required is that a spectrum from a standard for that nucleus is obtained. Thus this method does not require any 'internal' (intrinsic to the tissue) standard, and is extremely quick and simple to use.

Adenosine Triphosphate↗
PubMedDate not supplied

Organization and interrelationship of neuropeptides in the central amygdaloid nucleus of the rat.

The organization and interactions of neuropeptides in the central nucleus of the amygdala (Ce) were studied using single and double label immunocytochemical techniques. Immunocytochemical localization of substance P (SP), neurotensin (NT), met-enkephalin (m-ENK), somatostatin (SS) and vasoactive intestinal polypeptide (VIP) revealed all of these peptides within discrete regions of the Ce. The regions differed from the classical medial and lateral anatomical divisions reported for the Ce. Instead, three easily recognizable neuropeptidergic subdivisions were evident: a medial zone, a central zone and a lateral capsular zone. Two types of interrelationships between peptides were noted. The first involved a peptidergic fiber in apposition to a peptidergic perikarya. The most prevalent peptidergic interaction of this type occurred between SP and NT. The second interrelationship involved two different peptidergic fibers in apposition to an immunonegative cell. Two interactions of this type were commonly observed. The first involved NT and m-ENK fibers simultaneously apposed to an unstained cell. The second involved SP and m-ENK fibers adjacent to the same immunonegative cell. The interactions between peptidergic systems may suggest a role of these substances in the regulation of autonomic functions in the Ce.

Amygdala↗
PubMedDate not supplied

Slice cultures of LHRH neurons in the presence and absence of brainstem and pituitary.

Luteinizing hormone releasing hormone (LHRH) neurons from the preoptic area (POA)/hypothalamus of the postnatal rat were cultured for up to 7 weeks using a slice explant roller culture technique. The slices thinned to quasi-monolayers, but maintained organotypic distributions of large numbers of immunocytochemically identifiable LHRH, neurotensin, tyrosine hydroxylase, neurophysin and corticotropin releasing hormone-containing neurons. The distribution, survival and morphology of LHRH cells in co-cultures with brainstem and anterior pituitary was quantitated, and found to be similar to that observed in single cultures. LHRH fibers grew into either pituitary or brainstem tissue, however when all three tissues were co-cultured, LHRH fibers preferentially invaded the pituitary. LH immunoreactive anterior pituitary gonadotropes were maintained only in co-cultures containing POA/hypothalamic slices, and addition of an LHRH antagonist in such cultures, inhibited LH immunoreactivity in the gonadotropes. This slice explant roller culture method effectively maintains the cyto- and chemoarchitecture and functional properties of the LHRH system for long periods in vitro and should provide excellent models for studying the interactive and molecular characteristics of postnatal LHRH neurons.

Animals↗
PubMedDate not supplied

Relationship of catecholamines and LHRH: light microscopic study.

A wealth of evidence suggests that catecholamines influence gonadotrophin secretion. To assess whether this interaction involved LHRH cells or their processes, the distribution of the catecholamine synthesizing enzyme, tyrosine hydroxylase (TH) was examined with reference to the LHRH system in the adult male mouse brain. Alternate 30-50 micron sections cut on a vibrating microtome were stained immunocytochemically for TH and LHRH. These studies revealed the presence of catecholamine fibers in the areas of LHRH cells. Co-localization of TH and LHRH with a dual immunoperoxidase technique in single 20-25 micron sections showed a juxtaposition of catecholamine fibers on LHRH cells and their dendrites. All LHRH cells did not appear contacted. In addition, LHRH axons were in close apposition to the dopamine cells of the arcuate nucleus and periventricular hypothalamus. Within the median eminence, the anatomical distribution of LHRH and TH was differentially organized with few areas of overlap. These results support a direct action of catecholamines on the LHRH system and suggest that LHRH may influence dopamine function.

Animals↗
PubMedDate not supplied

A barter system.

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Community Participation↗