The nerve circuits for motility control in the gastrointestinal tract.
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Animals↗
Biomedical subjects
H M Young
Publications and source records attributed to H M Young.
Partners in care in a retirement community.
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Aged↗
Case management in a retirement community.
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Aged↗
Co-localization of nitric oxide synthase immunoreactivity and NADPH diaphorase staining in neurons of the guinea-pig intestine.
Neuronal nitric oxide synthase (NOS), an enzyme capable of synthesizing nitric oxide, appears to be identical to neuronal NADPH diaphorase. The correlation was examined between NOS immunoreactivity and NADPH diaphorase staining in neurons of the ileum and colon of the guinea-pig. There was a one-to-one correlation between NOS immunoreactivity and NADPH diaphorase staining in all neurons examined; even the relative staining intensities obtained were similar with each technique. To determine whether pharmacological methods could be employed to demonstrate that NADPH diaphorase staining was due to the presence of NOS, tissue was pre-treated with NG-nitro-L-arginine, a NOS inhibitor, or L-arginine, a natural substrate of NOS. In these experiments on unfixed tissue, it was necessary to use dimethyl thiazolyl tetrazolium instead of nitroblue tetrazolium as the substrate for the NADPH diaphorase histochemical reaction. Neither treatment caused a significant decrease in the level of NADPH diaphorase staining, implying that arginine and NADPH interact at different sites on the enzyme.
Amino Acid Oxidoreductases↗
Nitric oxide synthase immunoactivity and NADPH diaphorase enzyme activity in neurons of the gastrointestinal tract of the toad, Bufo marinus.
The presence of nitric oxide synthase (NOS) was demonstrated immunohistochemically, and NADPH diaphorase was demonstrated by enzyme histochemistry in neurons throughout the gastrointestinal tract of the anuran amphibian, Bufo marinus. Successive staining showed that NOS immunoreactivity and NADPH diaphorase activity occurred in precisely the same subgroup of enteric neurons. Subsequent detailed studies of the distribution of these neurons were made using NADPH diaphorase histochemistry. Numerous reactive nerve cell bodies and fibres were found in the myenteric plexus from the esophagus to the cloaca. A dense innervation of the longitudinal and circular muscle layers occurred throughout the gastrointestinal tract. The lamina muscularis mucosae was only prominent in the stomach, where it was sparsely innervated. Reactive nerve cell bodies were common in the submucosa of the large intestine, less common in the small intestine and extremely rare in the stomach and esophagus. Reactive fibres contributed to subepithelial plexuses in the esophagus, colon, rectum and cloaca. It is concluded that NOS/NADPH diaphorase is conserved amongst vertebrate classes and that NO is a likely neurotransmitter in the toad gastrointestinal tract.
Amino Acid Oxidoreductases↗
Rod-signal interneurons in the rabbit retina: 1. Rod bipolar cells.
The cellular morphology and topographic distribution of the rod bipolar cells in the rabbit retina have been investigated by selective labelling with protein kinase C-immunohistochemistry (Negishi et al., Neurosci, Lett. 94:247-252, 1988) and by Lucifer Yellow injection of microscopically identified cells in a superfused retinal preparation. The distribution of the rod bipolar cells parallels that of their input neurons, the rod photoreceptors, in that the rod bipolars reach maximum densities of 5,000-7,000 cells/mm2 on the inferior and superior flanks of the visual streak, dropping to slightly lower densities at the peak visual streak. The centre-to-periphery density gradient of the rod bipolars is about 2.5:1, and the density ratio of rods to rod bipolars shows little variation across the retina, ranging from 43:1 in superior retina to 58:1 in inferior retina. The dendritic field area of the rod bipolar cells increases from 600 microns2 on the visual streak to 1,200 microns2 in the far-superior retina, with each point on the retina overlapped by 2.5-3.5 dendritic fields. The axonal field area of the rod bipolar cells increases from about 100 microns2 at the peak visual streak to about 250 microns2 at the retina edge, and the axonal field coverage ranges from 0.55 in the visual streak to about 0.8 in peripheral retina. Although there appear to be gaps in the local array of rod bipolar somata, these areas are covered by the axonal arbours of neighbouring rod bipolar cells.
Animals↗
Rod-signal interneurons in the rabbit retina: 2. AII amacrine cells.
AII amacrine cells, which are the third-order neurons in the rod pathway, can be differentially labelled in rabbit retina by injecting Nuclear Yellow into the posterior chamber. Under ultraviolet excitation, the labelled retina appears strongly metachromatic, with the AII nuclei fluorescing silvery-yellow and the nuclei of other amacrine cells fluorescing blue. Labelled AII cells were injected with Lucifer Yellow under direct microscopic control in a superfused retinal preparation, and the dye was later photoconverted to an opaque reaction product. Rabbit AII amacrines, which number about 525,000 cells, reach a maximum density of 2,500-3,000 cells/mm2 on the peak visual streak, dropping to 400-500 cells/mm2 at the superior margin. These narrow-field amacrines have a bistratified dendritic morphology, with distinctive "lobular appendages" in sublamina a of the inner plexiform layer and wider ranging "arboreal dendrites" in sublamina b. Although the lobular field area increases 10-fold from the visual streak to the far periphery, the lobular field coverage is almost uniform across the retina, averaging 1.0 in inferior retina and 0.8 in superior retina. The dendritic field area of the arboreal dendrites also increases with eccentricity from the visual streak, but there are pronounced differences between inferior and superior retina. The arboreal fields are 2 to 3 times larger than the lobular fields throughout the inferior retina but up to 15 times larger in the superior retina. The arboreal field overlap is only 1.8 at the peak visual streak, increasing slightly to about 2.4 over most of the inferior retina; the overlap increases sharply in the superior retina, however, reaching values of 10 or more in the far periphery. Both the lobular and arboreal fields of AII cells are spaced more regularly than the somata, thus covering apparent gaps in the somatic array. An analysis of the potential convergence and divergence between rod bipolar cells and AII amacrine cells in the rabbit retina indicates that the neuronal architecture of the rod circuit is not organized in a uniform module that is simply scaled-up from central to peripheral retina. Moreover, peripheral fields in the superior and inferior retina that have equivalent densities of interneurons show markedly different rod bipolar----AII amacrine convergence ratios, with the result that many more rod photoreceptors converge on an AII amacrine cell in the superior retina than in the inferior retina.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
Operationalizing the theory of planned behavior.
The Theory of Planned Behavior (TPB) is an expectancy-value theory that provided a framework for the study of behavioral and normative beliefs affecting health behaviors. The purpose of this article is to describe operationalization of the TPB. The process of instrument development is explicated, with examples from two studies of BSE behavior in older women. Potential threats to reliability are discussed.
Aged↗
Cone photoreceptors lacking oil droplets in the retina of the echidna, Tachyglossus aculeatus (Monotremata).
The echidna, Tachyglossus aculeatus, a monotreme mammal, is thought to possess an all-rod retina (O'Day, 1952). This study provides anatomical evidence for the presence of cone-like photoreceptors in the retina of the echidna. The cones, which constitute 10-15% of the photoreceptors, have all of the ultrastructural characteristics previously shown in the cones of placental mammals, and, like cones of other animals (Blanks & Johnson, 1984), they bind peanut agglutinin. Unlike the cones of another monotreme, the platypus, the cones of the echidna retina do not possess oil droplets. Twin cones, pairs of cones in which there is no obvious difference in the size, shape, or ultrastructural features of the members of a pair, are common. The density of cones varies from 9000 cells/mm2 in the superior periphery to 22,000 cells/mm2 in the central retina. Nearest-neighbor analysis suggests that the cone mosaic in the echidna retina results from the presence of single and twin cones in a relatively regular array.
Animals↗
Predictors of burden in spouse caregivers of individuals with Alzheimer's disease.
This study used the following model of distress: Distress = [Exposure to Stress + Vulnerability]/[Psychological and Social Resources]. The constructs in the model were operationalized as (a) distress in response to caregiver experiences (burden); (b) exposure to stress (care recipient functional impairment in activities of daily living [ADLs]); (c) vulnerability (caregiver health problems, anger, and anxiety); and (d) resources (coping, outlook on life, and social supports). Long-term burden (15-18 months after entry) was predicted by several baseline variables: burden, care recipient ADLs, vulnerability and resource variables, and specific interactions of burden, ADLs, vulnerability, and resource variables. The interactions showed that caregivers with high vulnerability and low resources had higher burden scores than caregivers with other combinations of these variables.
Activities of Daily Living↗
Burden: a review of measures used among caregivers of individuals with dementia.
This paper critiques and discusses 10 measures of burden that have been used with caregivers of individuals with dementia. Current measures target diverse caregiver and care recipient populations, and vary in conceptualization and measurement of burden. Although many measures contain reliability data, relatively few report content validity, convergent/divergent validity, criterion validity, or sensitivity to change. Implications of these limitations for research and clinical practice are discussed.
Alzheimer Disease↗
The screen for caregiver burden.
The Screen for Caregiver Burden (SCB) is a measure designed to identify distressing caregiver experiences rapidly. The 25-item SCB, created specifically for spouse caregivers of Alzheimer's care recipients, provides scores for objective burden (OB; number of potentially negative experiences) and subjective burden (SB; appraised distress in response to the experiences). Three separate studies (total N = 191) demonstrate the internal consistency, test-retest reliability, and validity (content, divergent, convergent, and criterion) of the scales. Finally, evidence suggests that changes in OB and SB over time are explained by changes in care-recipient functioning and caregiver distress.
Aged↗
Another look at hardiness.
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Adaptation, Psychological↗
The retinae of Prototherian mammals possess neuronal types that are characteristic of non-mammalian retinae.
This study has shown that the retinae of Prototherian (egg-laying) mammals possess two neuronal types that are present in non-mammalian retinae, but absent or morphologically different in the retinae of Eutherian (placental) mammals. First, endogenous serotonin-like immunoreactivity has been localized in a population of presumptive amacrine cells in the platypus retina, the first such report in a mammalian retina. Second, the protein kinase C-immunoreactive (PKC-IR) bipolar cells in the echidna retina appear similar to the PKC-IR bipolars in the chicken retina, in that their dendrites give rise to a Landolt's club and their axons are multistratified. By contrast, the PKC-IR rod bipolar cells in the rabbit and in the brushtail possum, a Metatherian (marsupial) mammal, have no Landolt's clubs and their axons form terminal lobes in the innermost stratum of the inner plexiform layer.
Animals↗
The transition of relocation to a nursing home.
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Adaptation, Psychological↗
Resilience among older women.
This qualitative study was designed to identify and describe characteristics of successfully adjusted older women. The participants reported a recent major loss and were considered successfully adjusted as evidenced by social involvement in a senior center, a mid level to high level of morale and self-report. Using a grounded theory approach, five underlying themes were identified: equanimity, self-reliance, existential aloneness, perseverance and meaningfulness. These themes are thought to constitute resilience. Lateral grounding of the concept resilience is accomplished by comparison with philosophical writings of Frankl, Bettelheim, Frank, May and von Witzleben. Resilience is important in late life as a component of successful psychosocial adjustment.
Adaptation, Psychological↗
The morphology and topographic distribution of substance-P-like immunoreactive amacrine cells in the cat retina.
In cat retinal wholemounts, substance-P-like immunoreactivity (SP-IR) was localized in a distinct population of amacrines whose cell bodies were normally placed in the ganglion cell layer. Although displaced amacrines accounted for 80-95% of the SP-IR amacrines in peripheral retina, this proportion decreased considerably within the area centralis, accounting for 50-80% of the labelled cells at maximum density. The SP-IR cells in both the inner nuclear and ganglion cell layers gave rise to well-defined varicose dendrites of uniform appearance that stratified around 60% depth (S3/S4) of the inner plexiform layer. In addition, sparse fine dendrites in stratum 1 (S1) could sometimes be traced to inner nuclear cells and occasionally to displaced amacrines. The combined SP-IR cell density ranged from less than 50 cells mm-2 in the far periphery to more than 500 cells mm-2 in the area centralis; the maximum density showed little individual variation despite wide differences in the proportion of displaced cells. The 39,000 SP-IR amacrines in a mapped retina had a triangular topographic distribution, with intermediate isodensity lines extending vertically in superior retina and horizontally along both arms of the visual streak. Colocalization experiments established that all SP-IR cells in cat retina showed GABA-like immunoreactivity, and that the SP-IR amacrines were quite distinct from the cholinergic amacrines identified by choline acetyltransferase immunohistochemistry.
Animals↗
The vesicle content of catecholamine-containing axons in the rectum of the domestic fowl: effect of permanganate and chromaffin fixations.
The ultrastructural appearance of catecholamine-containing (CA) axon profiles in the rectum of the domestic fowl was compared following fixation using the chromaffin reaction or potassium permanganate. As described previously, after chromaffin fixation CA-axons in the perivascular plexuses contained many small granular vesicles (SGV) and variable numbers of large granular vesicles (LGV), whereas those in the non-vascular sites contained few small vesicles and were characterised by the presence of elongated LGV. Following fixation in potassium permanganate, CA-axons in both the non-vascular and vascular sites contained many SGV. The SGV were accompanied by variable numbers of large round vesicles which were often devoid of a core. Large vesicles comprised 16 and 26%, respectively, of total vesicles in the vascular and non-vascular axon profiles. The total number of vesicles per CA-axon profile in both the vascular and non-vascular site was not dependent on fixation procedure. It is concluded that the vesicle content of CA-axon profiles in the rectum of the domestic fowl is dependent on the fixative employed.
Animals↗