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Biomedical subjects

R B Kelly

Publications and source records attributed to R B Kelly.

At least 91 records · Page 5Linked to original sources
PubMed1991

Prediction of motivation and behavior change following health promotion: role of health beliefs, social support, and self-efficacy.

Dimensions of health beliefs (perceived risk of behavior and benefit of behavior change), social support (family and others' support for change), and self-efficacy (magnitude and strength) were examined in 215 patients undergoing a prospective trial of health promotion in a primary care medical practice. Discriminant analyses were performed to evaluate how well these dimensions predicted motivation for change and lifestyle behavior change. These relationships were examined for six lifestyle areas: cigarette smoking, dealing with stress, amount and type of food eaten, use of seat belts, and exercise habits. The analyses demonstrated a statistically and clinically significant prediction of motivation by one or more health belief and self-efficacy dimensions for most lifestyle areas. The strongest single predictors were perceived benefits and self-efficacy strength, which were each significant predictors of motivation in four lifestyle areas (P less than 0.05). Support dimensions, as measured, were not shown to have predictive value in most areas. Behavior change was poorly predicted by beliefs, support, and self-efficacy for most lifestyle areas. However, adding motivation to the discriminant function equation resulted in significant predictions in all six lifestyle areas (P less than 0.05), with an average correct classification rate of 71%. This finding strongly suggests that motivation is a very important intervening variable when evaluating health promotion and resulting behavior change.

Adolescent↗
PubMed1991

Synaptophysin is sorted from endocytotic markers in neuroendocrine PC12 cells but not transfected fibroblasts.

The targeting of synaptophysin, a major synaptic vesicle protein, in transfected nonneuronal cells has important implications for synaptic vesicle biogenesis, but has proved controversial. We have analyzed four transfected cell types by differential centrifugation and velocity gradient sedimentation to determine whether synaptophysin is targeted to endosomes or to synaptic vesicle-like structures. Synaptophysin was recovered only in vesicles that sedimented more rapidly than synaptic vesicles. The synaptophysin-containing vesicles were labeled if a surface-labeled cell was warmed to 37 degrees C, comigrated with transferrin receptor-containing vesicles on velocity and density gradients, and could be completely immunoadsorbed by anti-LDL receptor tail antibodies. These data demonstrate that synaptophysin was targeted to the early endocytotic pathway in the transfected cells and are inconsistent with the suggestion that synaptophysin expression induces a novel population of vesicles. Targeting of synaptophysin to early endosomes implicates their role in synaptic vesicle biogenesis.

Adrenal Gland Neoplasms↗
PubMed1991

Secretory granule and synaptic vesicle formation.

Sorting of secreted proteins into dense-core secretory granules may involve selective aggregation of regulated secretory proteins, rather than a conventional sortase. Synaptic vesicles, which mediate paracrine communication between adjacent cells, appear to arise by a modification of the early endosome pathway. Targeting to the cell surface involves the actin-based cytoskeleton and small GTP-binding proteins.

Animals↗
PubMed1991

Molecular architecture of the nerve terminal.

The synaptic vesicle has been the focus of recent efforts to generate a molecular description of the nerve terminal. The function and molecular composition of the synaptic vesicle are well characterized, due in part to its relative simplicity. Recent work identifies specific proteins involved in some of the functions of the synaptic vesicle and their mechanism of action.

Animals↗
PubMed1991

Constitutive and basal secretion from the endocrine cell line, AtT-20.

A variant of the ACTH-secreting pituitary cell line, AtT-20, has been isolated that does not make ACTH, sulfated proteins characteristic of the regulated secretory pathway, or dense-core secretory granules but retains constitutive secretion. Unlike wild type AtT-20 cells, the variant cannot store or release on stimulation, free glycosaminoglycan (GAG) chains. In addition, the variant cells cannot store trypsinogen or proinsulin, proteins that are targeted to dense core secretory granules in wild type cells. The regulated pathway could not be restored by transfecting with DNA encoding trypsinogen, a soluble regulated secretory protein targeted to secretory granules. A comparison of secretion from variant and wild type cells allows a distinction to be made between constitutive secretion and basal secretion, the spontaneous release of regulated proteins that occurs in the absence of stimulation.

Adrenocorticotropic Hormone↗
PubMed1991

Endocytosis of the synaptic vesicle protein, synaptophysin, requires the COOH-terminal tail.

Synaptic vesicles participate in a cycle of fusion with the plasma membrane and reformation by endocytosis. Endocytosis of membrane proteins by the well studied clathrin-coated vesicle pathway has been shown to involve specific sequences within the cytoplasmic tail domain. Proteins taken up by clathrin-coated vesicles are directed to early endosomes from which they may return to plasma membrane. Recent evidence suggests that the synaptic vesicle protein synaptophysin is targeted to early endosomes in transfected fibroblasts and in neuroendocrine cells. To begin to test whether sequences within the COOH-cytoplasmic domain are required for internalization we have expressed a synaptophysin molecule lacking this domain in 3T3 cells and measured its rate of internalization. While a full length synaptophysin was internalized efficiently, we could not detect internalization of the mutant construct. These data are consistent with a model in which the COOH-terminal tail is required for coated-pit localization and hence targeting of synaptophysin to early endosomes.

Animals↗
PubMed1991

Serum cholesterol: attitudes and behavior of family practice residents.

BACKGROUND: Given the current health promotion efforts regarding coronary artery disease, more information is needed about residents' attitudes and behaviors that relate to identification and management of patients with elevated serum cholesterol levels. METHODS: Family practice residents from eight US programs (N = 128) were surveyed in 1989 to assess their attitudes and reported practice patterns. Resident survey data were compared, when feasible, to published data from 1986 and 1990 surveys of practicing physicians performed by the National Heart, Lung, and Blood Institute. RESULTS: The use of faculty "key contacts" resulted in a 90% response rate (N = 115). Both residents and practicing physicians attributed a high degree of importance to cholesterol as a risk factor. Residents reported more frequent routine screening of middle-aged men than the routine screening rate of practicing physicians in 1986 (P less than .01). Residents reported less frequent screening of younger and older adults than of middle-aged men (P less than .001). Residents' threshold for the use of cholesterol-lowering medication was lower than that of practicing physicians surveyed in 1986, but higher than that of physicians surveyed in 1990. Compared with practicing physicians, residents did not believe they were as well prepared to counsel patients about dietary change or as successful when they tried to help patients make changes; residents reported a significantly higher rate of referral to dietitians (P less than .01). CONCLUSIONS: Residents may need more education regarding screening guidelines for children and young adults. A health promotion skills gap may exist that explains reported discrepancies between self-report and actual behavior and indicates that residency educators may need to pay more attention to fostering dietary assessment and counseling skills in their residents.

Adult↗
PubMed1990

Endocytic membrane traffic to the Golgi apparatus in a regulated secretory cell line.

We have established a ricin-resistant glycosylation-defective PC12 pheochromocytoma cell line to study biochemically glycoprotein traffic from the cell surface to the Golgi apparatus in regulated secretory cells. The strategy employed in this study is a modification of that used previously (Duncan, J. R., and Kornfeld, S. (1988) J. Cell Biol. 106, 617-628) to demonstrate transport of the cation-independent and -dependent mannose 6-phosphate receptors from the cell surface to the trans-Golgi network in nonsecretory cell types. In ricin-resistant PC12 cells, radiolabeled galactose was incorporated enzymatically into surface glycoconjugates, primarily glycoproteins. Resistance to beta-galactosidase was acquired upon reculture at 37 degrees C due to further terminal glycosylation of the galactose residues. Treatment of N-linked oligosaccharides isolated from recultured cells with a variety of glycosidases in conjunction with beta-galactosidase demonstrated the addition of sialic acid N-acetylglucosamine and fucose residues to the galactose residues in recultured cells. Resistance to beta-galactosidase was not acquired in cells recultured at 19 degrees C, indicating that subsequent glycosylation of galactose residues did not occur at the cell surface or in endosomes. While glycosylation of galactose incorporated into asparagine oligosaccharides in Chinese hamster ovary clone 13 cells was not significant (less than 1%) after 6 h of reculture, approximately 10% of the galactose incorporated into surface oligosaccharides was further glycosylated in PC12 cells in this time. Analysis of total labeled versus beta-galactosidase-resistant proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated that endocytic traffic to the site of glycosylation activity in mutant PC12 cells was highly selective, but included a much greater number of proteins than were detected in Chinese hamster ovary clone 13 fibroblasts.

Adrenal Gland Neoplasms↗
PubMed1990

Biogenesis of synaptic vesicle-like structures in a pheochromocytoma cell line PC-12.

The presence of unique proteins in synaptic vesicles of neurons suggests selective targeting during vesicle formation. Endocrine, but not other cells, also express synaptic vesicle membrane proteins and target them selectively to small intracellular vesicles. We show that the rat pheochromocytoma cell line, PC12, has a population of small vesicles with sedimentation and density properties very similar to those of rat brain synaptic vesicles. When synaptophysin is expressed in nonneuronal cells, it is found in intracellular organelles that are not the size of synaptic vesicles. The major protein in the small vesicles isolated from PC12 cells is found to be synaptophysin, which is also the major protein in rat brain vesicles. At least two of the minor proteins in the small vesicles are also known synaptic vesicle membrane proteins. Synaptic vesicle-like structures in PC12 cells can be shown to take up an exogenous bulk phase marker, HRP. Their proteins, including synaptophysin, are labeled if the cells are surface labeled and subsequently warmed. Although the PC12 vesicles can arise by endocytosis, they seem to exclude the receptor-mediated endocytosis marker, transferrin. We conclude that PC12 cells contain synaptic vesicle-like structures that resemble authentic synaptic vesicles in physical properties, protein composition and endocytotic origin.

Animals↗
PubMed1990

Continuity of care in a family practice residency program. Impact on physician satisfaction.

One of the primary benefits of continuity of care is its influence upon patient and physician satisfaction. This prospective pilot study involved a cohort of 14 second- and third-year family practice residents and 4 full-time faculty at a community hospital-based family practice residency in Cleveland, Ohio. Rates of continuity that physicians experience were calculated using the usual provider continuity (UPC) measure of continuity, and were correlated with physician satisfaction with outpatient care using a practice satisfaction scale (PSS) developed specifically for this purpose. Residents and faculty were also asked to rank order the importance of several aspects of outpatient care, including continuity of care. The results indicate that both residents and faculty value continuity of care highly compared with other aspects of outpatient care. The average continuity rates were 59% for second-year residents, 54% for third-year residents, and 82% for faculty. The UPC continuity measure correlated highly with the PSS scores (corrected r2 = .55; P less than .001). The data support the hypothesis that continuity of care with patients is an important determinant of resident and faculty physician satisfaction with their outpatient experience.

Adolescent↗
PubMed1989

Interaction of heavy chain binding protein (BiP/GRP78) with adenine nucleotides.

Immunoglobulin heavy chain binding protein (BiP/GRP78) is a resident endoplasmic reticulum protein that binds tightly to a number of incompletely assembled or aberrant proteins. BiP also binds ATP and can be purified by ATP affinity chromatography. Here we show that an ATPase activity co-purifies with BiP prepared from canine pancreas. The BiP-associated ATPase has a high affinity for ATP but a low turnover number, suggesting a regulatory, rather than an enzymatic role. We also show that submicromolar levels of ATP or ADP decrease the rate of adsorption of [125I]BiP to nitrocellulose filters coated with protein or non-ionic detergents. In contrast, micromolar levels of AMP increase the rate of adsorption. Furthermore, ATP and ADP decrease the susceptibility of BiP to proteolytic degradation, whereas AMP was found to enhance degradation slightly. Adenine nucleotides may therefore induce or stabilize different conformations of BiP even when ATP hydrolysis does not occur.

Adenine Nucleotides↗
PubMed1989

Sonography of placental abnormalities and oligohydramnios in women with elevated alpha-fetoprotein levels: comparison with control subjects.

To evaluate the relationship of placental and amniotic fluid findings to elevated maternal serum alpha-fetoprotein (MS-AFP) levels, we compared sonograms made between 18 and 24 weeks gestational age in 76 women with elevated MS-AFP levels with sonograms of a control group. Patients with fetal malformations, incorrect dates, twins, or lack of follow-up were excluded. Overall, 27 (36%) of 76 patients with elevated MS-AFP levels had placental or amniotic fluid abnormalities compared with only three (3%) of 87 control subjects. Significant differences (p less than .01) were noted in the frequency of periplacental hemorrhage (9% vs 0%), intraplacental sonolucencies greater than or equal to 1.5 cm in diameter (18% vs 3%) and moderate or severe oligohydramnios (17% vs 0%). More patients with elevated MS-AFP levels had placenta previa (4%) or placental thickness greater than or equal to 3.5 cm (12%) than did those in the control group (1% and 5%, respectively), although these differences did not reach statistical significance. Seven (26%) of the 27 patients had more than one abnormality. We conclude that placental and/or amniotic fluid abnormalities are frequently shown on sonograms in women who are examined because of elevated MS-AFP levels.

Amniotic Fluid↗