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Biomedical subjects

H M Young

Publications and source records attributed to H M Young.

At least 91 records · Page 5Linked to original sources
PubMed1988

GABA-like immunoreactivity in NADPH-diaphorase amacrine cells of the rabbit retina.

NADPH-diaphorase histochemistry selectively stains discrete populations of retinal interneurons in diverse mammals, including two amacrine types in the rabbit retina. In this study, we have demonstrated that most of these neurons show GABA-like immunoreactivity by combining indirect immunofluorescence and diaphorase histochemistry on frozen retinal sections. The NADPH-diaphorase amacrines account for only a small proportion of the GABA-positive cells in rabbit retina, thus reinforcing the emerging consensus that GABAergic amacrines are remarkably diverse in their morphology and function.

Animals↗
PubMed1988

GABA-like immunoreactivity in cholinergic amacrine cells of the rabbit retina.

In the ganglion cell layer of the rabbit retina, the inhibitory transmitter gamma-aminobutyric acid (GABA) and its analogues are accumulated by neurons that appear to match in size and number the population of displaced amacrine cells that synthesize the excitatory transmitter acetylcholine. In this double-label study, we have established directly that the cholinergic amacrine cells, selectively stained with diamidino-phenylindole, are strongly immunoreactive with GABA antisera. The coexistence of two classical transmitters, one excitatory and the other inhibitory, in this defined neuronal population, suggests that stimulation of the cholinergic amacrines may give rise to complex responses in their target neurons.

Acetylcholine↗
PubMed1984

Effects of canal lubrication on retention of cemented posts.

The effect of lubricating the canal space prior to making a custom acrylic post pattern was studied in regard to the retention of cast posts cemented with zinc phosphate. Ways of removing the lubricant before cementation were also evaluated.

Acrylic Resins↗
PubMed1983

Ultrastructure of catecholamine-containing axons in the intestine of the domestic fowl.

Axons in the duodenum, ileum and rectum of the domestic fowl were identified as catecholamine-containing (CA) on the basis of positive reactivity following chromaffin fixation for electron microscopy. CA-axons in association with blood vessels in all regions of the intestine and in non-vascular sites in the small intestine had a 'typical' adrenergic appearance, in that they contained many small granular vesicles (SGV) and variable numbers of large granular vesicles (LGV). In the rectum the non-vascular CA-axon profiles were atypical, in that there were many elongated LGV and few SGV, and the chromaffin reactivity was weak. The nerve profiles in the rectum were dramatically reduced following 6-hydroxydopamine and reserpine treatment and were absent in rectum cultured in the absence of extrinsic ganglia. It was concluded that the profiles, in spite of their low chromaffin reactivity, truely represent CA-axons. The possibility was raised that the atypical morphology and reduced chromaffin reactivity is due to the presence of adrenaline.

Animals↗
PubMedDate not supplied

Relationships between nitric oxide synthase, vasoactive intestinal peptide and substance P immunoreactivities in neurons of the amphibian intestine.

Nitric oxide synthase (NOS)-containing neurons (localized using NADPH diaphorase histochemistry or NOS immunoreactivity) and vasoactive intestinal peptide-immunoreactive (VIP-IR) neurons were found in the myenteric plexus of the gastrointestinal tract of the amphibian, Bufo marinus. Only limited co-localization of the two substances was observed in nerve cell bodies, about 11% of the NOS-containing neurons were also labelled by VIP-IR and about 37% of VIP-IR nerve cell bodies contained NOS. The relationship between VIP, NOS and SP-IR in nerve fibres in the circular muscle was examined. There was partial co-localization of VIP and NOS, but no co-localization of NOS or VIP with substance P. Of fibres that were immunoreactive for VIP or NOS, fewer than 10% contained VIP alone.

Amino Acid Oxidoreductases↗
PubMedDate not supplied

The rod circuit in the rabbit retina.

Mammalian retinae have a well-defined neuronal pathway that serves rod vision. In rabbit retina, the different populations of interneurons in the rod pathway can be selectively labeled, either separately or in combination. The rod bipolar cells show protein kinase C immunoreactivity; the rod (AII) amacrine cells can be distinguished in nuclear-yellow labeled retina; the rod reciprocal (S1 & S2) amacrine cells accumulate serotonin; and the dopaminergic amacrine cells show tyrosine-hydroxylase immunoreactivity. Furthermore, intracellular dye injection of the microscopically identified interneurons enables whole-population and single-cell studies to be combined in the same tissue. Using this approach, we have been able to analyze systematically the neuronal architecture of the rod circuit across the rabbit retina and compare its organization with that of the rod circuit in central cat retina. In rabbit retina, the rod interneurons are not organized in a uniform neuronal module that is simply scaled up from central to peripheral retina. Moreover, peripheral fields in superior and inferior retina that have equivalent densities of each neuronal type show markedly different rod bipolar to AII amacrine convergence ratios, with the result that many more rod photoreceptors converge on an AII amacrine cell in superior retina. In rabbit retina, much of the convergence in the rod circuit occurs in the outer retina whereas, in central cat retina, it is more evenly distributed between the inner and outer retina.

Animals↗
PubMedDate not supplied

The DAPI-3 amacrine cells of the rabbit retina.

In the rabbit retina, the nuclear dye, 4,6,diamidino-2-phenylindole (DAPI), selectively labels a third type of amacrine cell, in addition to the previously characterized type a and type b cholinergic amacrine cells. In this study, these "DAPI-3" amacrine cells have been characterized with respect to their somatic distribution, dendritic morphology, and neurotransmitter content by combining intracellular injection of biotinylated tracers with wholemount immunocytochemistry. There are about 100,000 DAPI-3 amacrine cells in total, accounting for 2% of all amacrine cells in the rabbit retina, and their cell density ranges from about 130 cells/mm2 in far-peripheral retina to 770 cells/mm2 in the visual streak. The thin varicose dendrites of the DAPI-3 amacrine cells form a convoluted dendritic tree that is symmetrically bistratified in S1/S2 and S4 of the inner plexiform layer. Tracer coupling shows that the DAPI-3 amacrine cells have a fivefold dendritic-field overlap in each sublamina, with the gaps in the arborization of each cell being occupied by dendrites from neighboring cells. The DAPI-3 amacrine cells consistently show the strongest glycine immunoreactivity in the rabbit retina and they also accumulate exogenous [3H]-glycine to a high level. By contrast, the AII amacrine cells, which are the best characterized glycinergic cells in the retina, are amongst the most weakly labelled of the glycine-immunopositive amacrine cells. The DAPI-3 amacrine cells costratify narrowly with the cholinergic amacrine cells and the On-Off direction-selective ganglion cells, suggesting that they may play an important role in movement detection.

Animals↗
PubMedDate not supplied

Balancing freedom with risks: the experience of nursing task delegation in community-based residential care settings.

BACKGROUND: In 1995, Washington State implemented law reforming the state's long-term care system, favoring provision of service in less restrictive, lower-cost settings. PURPOSE: The purpose was to systematically evaluate one facet of the new law regarding the implementation of a policy authorizing delegation of designated nursing tasks by registered nurses in community-based residential care settings. METHOD: This was a descriptive study driven by the inductive process of grounded theory. Qualitative data sources included interviews, public forums, document review, and open-ended survey questions to facility operators, nurses, nursing assistants, and inspectors. DISCUSSION: The study identified an overarching social process, balancing freedom with risks involving tension at the intersections, which is evident from 3 main perspectives: consumer, professional, and the health care system. CONCLUSIONS: The study has implications for regulatory consistency, nursing practice and education, collaboration between overlapping providers of skilled nursing services in residential settings, and subsequent health policy.

Attitude of Health Personnel↗
PubMedDate not supplied

The theory of reasoned action in prediction of breast self-examination: a comparison of two studies.

The purpose of this article is to report the application of the theory of reasoned action (TRA) to predict breast self-examination (BSE) intention and frequency in two studies with middle-aged and older women. The sample in Study 1 consisted of 93 volunteers from church groups; the second sample consisted of 175 randomly selected subscribers to a large health maintenance organization. Questionnaires to measure attitudinal and subjective normative influences relevant to BSE were developed using guidelines specified by Ajzen and Fishbein (1980). The attitudinal components predicted BSE intention in both studies and BSE frequency in Study 1. In contrast, the subjective norm contributed significantly only to the prediction of frequency in Study 1. Findings demonstrate varying degrees of success for the TRA in predicting BSE intention and behavior. Explanations for the inconsistency in the predictive ability of the TRA can be related to differences between the two studies regarding sample and design characteristics.

Aged↗