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Biomedical subjects

A Hobson

Publications and source records attributed to A Hobson.

29 records · Page 2Linked to original sources
PubMed1994

Downregulation of cGMP phosphodiesterase induced by expression of GTPase-deficient cone transducin in mouse rod photoreceptors.

PURPOSE: Photoexcitation of vertebrate retinal rod photoreceptors stimulates GTP binding to the transducin alpha subunit. Like other GTP-binding proteins, transducin restores itself to an inactive form by hydrolyzing its bound GTP. The role of GTP hydrolysis in phototransduction was investigated. METHODS: A mutant form of cone transducin alpha deficient in its ability to hydrolyze bound GTP was expressed in mouse rod photoreceptors. RESULTS: Expression of the mutant cone transducin alpha at levels threefold to sixfold higher than endogenous rod transducin alpha led to a specific depletion of the transducin target, cGMP phosphodiesterase, and a decrease in the cGMP level. Suction electrode recordings revealed abnormally prolonged flash responses, decreased maximal response amplitudes, and a shift in the stimulus-response relation to higher flash strengths. CONCLUSIONS: Rods expressing high levels of GTPase-deficient cone transduction alpha have reduced levels of phosphodiesterase catalytic subunits and cGMP. These changes are associated with prolonged flash responses, reduced dark current, and decreased sensitivity to light.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1992

Patients with dementia involving families to maximize nursing care.

Incorporating family members in the care of patients with dementia provided pertinent psychosocial data, led to mutual decision-making regarding care, and produced changes in the responses of the residents with dementia, as well as in the family and nursing staff. The experimental group experienced increases in psychosocial nursing diagnoses with planning and interventions to meet the problems, more extensive problem description, and an active focus on interaction and change in the nurse's notes. As a result of collaborative nursing and family involvement, personal articles were brought from home; family collateral visits and interaction increased; families were more involved in the unit, medical center, and support groups; and p.r.n. medication use was decreased. As health-care technology prolongs the life of patients with chronic illness and sequelae such as dementia, nurses will need to continue to include families as collaborators in providing quality care.

Aged↗
PubMed1989

Distribution patterns of HP1, a heterochromatin-associated nonhistone chromosomal protein of Drosophila.

We have previously reported the identification of a nonhistone chromosomal protein (nhcp-19; now called HP1) preferentially associated with the heterochromatin of Drosophila melanogaster. A detailed study of the HP1 distribution pattern on polytene chromosomes by immunofluorescent staining, using monoclonal antibody C1A9, has been carried out. The results indicate that this protein is found within the centric beta-heterochromatin, in cytological regions 31, 41 and 80, and throughout polytene chromosome 4. Staining of telomeres is frequently observed, those of chromosome arms 2R and 3R and the X chromosome being the most conspicuous. Analysis of a fourth chromosome insertional translocation T(3;4)f/In(3L)P confirms an autonomous interaction with chromosome 4 material. Similarly, the beta-heterochromatin distal to light on chromosome arm 2L, moved to position 97D2 on chromosome arm 3R in the rearrangement ltx13, is prominently stained using the C1A9 antibody. Staining of intact salivary glands indicates that this rearranged segment of beta-heterochromatin is not associated with the polytene chromocenter, but provides an independent structural reference point. HP1 is not observed in the nuclei of the early syncytial embryo, but becomes concentrated in the nuclei at the syncytial blastoderm stage (ca. nuclear division cycle 10). This suggests that heterochromatin formation occurs at approximately the same stage at which nuclei first become transcriptionally competent. Thus, the C1A9 antibody may serve as a useful marker for both structural and functional studies of the Drosophila nucleus.

Animals↗
PubMed1985

Overproduction of the membrane-bound components of the histidine permease from Salmonella typhimurium: identification of the M protein.

The periplasmic histidine permease of Salmonella typhimurium is composed of a soluble histidine-binding protein and three membrane-bound components. These latter are produced in very small amounts and only two, the Q and the P protein, have been previously identified. This paper describes the construction of a plasmid carrying the hisQ, hisM, and hisP genes under the control of the lambda PL promoter, thus allowing great overproduction of those gene products. The M protein has been identified in such overproducing strains and its nature confirmed by constructing in vitro hisM deletions within the plasmid. With these results the identification of all components of the histidine permease has been completed.

ATP-Binding Cassette Transporters↗
PubMed1976

How many tastes are there for low concentration "sweet" and "sour" stimuli? - Threshold implications.

Ascending series of solutions of sucrose, glucose, and citric acid were tasted and detection and recognition thresholds were noted; subjects were also required to determine the number of taste sensations that occurred and their sequence of occurrence. It was found that subjects varied in their reports of the number of taste changes and hence potential criteria for detection and recognition. Even among those subjects who reported the same number of criteria there was little consistency as to which were actually chosen for detection and recognition. Some subjects even used an intensity change rather than a quality change to signal a threshold. They criterion can thus be seen to be a potential variable in threshold measurement, and criterion-free measures of sensitivity are recommended. Taste quality descriptions were also studied and a high proportion of novel descriptions was noted; it was hypothesised that this was due to the fact that subjects were not primed with traditional descriptive terms during the instructions.

Adolescent↗
PubMedDate not supplied

Comparative structural and functional analysis of photoreceptor neurons of Rho-/- mice reveal increased survival on C57BL/6J in comparison to 129Sv genetic background.

To explore the possible influence of defined genetic backgrounds on photoreceptor viability and function in mice carrying a targeted disruption of the rhodopsin gene, the severities of retinopathies in Rho-/- mice on C57BL/6J and 129Sv congenic backgrounds were compared by light microscopy and electroretinography and qualitatively by in situ end labeling of DNA in apoptotic photoreceptor nuclei of retinal sections. Cone photoreceptor viability and function were shown to deteriorate more slowly on the C57BL/6J background in comparison to that of the 129Sv, with significantly greater numbers of outer nuclear layer nuclei in the retinas of C57BL/6J mice at 3 and 4 months of age. Both amplitude and waveform features of the ERG were shown to be remarkably different in the two strains, indicating an approximately 6-fold difference in C57BL/6J Rho-/- mice compared to 129Sv Rho-/- mice at 80 days. Thus, in comparison with the 129Sv strain, genetic modifiers appear to constitute a component of the C57BL/6J background, the expression of which significantly protects cone photoreceptors from apoptotic death in a mutation-induced murine retinopathy. The differences in phenotype revealed in this study are sufficient in principle to provide a basis for comparisons to be made between QTLs in light-induced and mutation-induced systems.

Aging↗
PubMedDate not supplied

A systems approach to gathering and analyzing patient and family complaints and suggestions.

Most medical facilities' leaders are concerned with satisfying the patients who use their healthcare organization. Whereas many facilities have identified specific individuals whose job it is to hear patient complaints, the authors promote the view that all staff members play important roles in patient advocacy. Management's role is to determine how to collect and analyze the complaints and suggestions voiced by patients throughout their healthcare experience. This article presents one method.

California↗
PubMedDate not supplied

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Education, Nursing↗