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Biomedical subjects

C W Baker

Publications and source records attributed to C W Baker.

9 recordsLinked to original sources
PubMed2001

Automated, microprocessor controlled short path thermal desorption system for analysis of volatiles in foods.

An automated short path thermal desorption system gas chromatograph (GC) accessory was constructed to facilitate the unattended analysis of up to twelve individual samples. The system is personal computer controlled, operates directly on the GC with little or no modification, and was tested in both direct thermal and purge and trap thermal desorption mode. The apparatus was evaluated for overall performance, ruggedness, baseline blanks, efficiency, and precision. Mechanical performance was flawless and a clean baseline was obtained under high sensitivity GC-FID conditions. Linearity and precision was evaluated by quantifying butylated hydroxy toluene standards, safranal in saffron spice, and cinnamic aldehyde in cookies.

Adsorption↗
PubMed2000

Studying intergenerational transmission of eating attitudes and behaviors: methodological and conceptual questions.

Associations between parent and child attitudes and behaviors related to eating and weight were examined among college-age men and women and their mothers and fathers (ns = 44, 47, 87, and 66, respectively). Parent attitudes and behaviors were assessed from the perspective of the parent and the student, and 2 pathways of influence were examined: modeling and direct criticism. In general, students' attitudes and behaviors were more strongly related to perceptions of their parents rather than to parents' own self-reports. There was more support for perceived direct criticism as a pathway of influence, particularly for daughters. Perceived criticism about eating and appearance had large associations with student attitudes and behaviors. Weight loss behavior was related to perceived criticism among daughters and to perceived paternal eating attitudes among sons. Results highlight important methodological and conceptual questions for intergenerational research.

Adolescent↗
PubMed1999

Eating attitudes and behaviors in pregnancy and postpartum: global stability versus specific transitions.

Global changes in eating attitudes were examined prospectively across pregnancy and 4 months postpartum in a sample of 90 women. In addition, specific changes in dieting behavior and weight/shape satisfaction were assessed at 4 months postpartum for concurrent and retrospective time points. Measures included the Eating Attitudes Test (EAT) and weight/shape satisfaction in pregnancy and at 4 months postpartum, as well as prepregnancy, pregnancy, and postpartum weight loss efforts. While global EAT scores were stable across time, dieting scores (Factor I) increased between pregnancy and postpartum. Weight/shape satisfaction was higher in pregnancy, and satisfaction was related to EAT scores at 4 months postpartum but not during pregnancy. Prepregnancy dieters and nondieters were best discriminated by higher weights, elevated pregnancy dieting scores, and lower postpartum weight/shape satisfaction. Results emphasize the importance of looking beyond changes in global eating attitudes and behaviors to more specific eating concerns or behaviors. Lastly, the results have implications for identifying women at risk for eating- and weight-related concerns during this period of rapid physical change.

Adaptation, Psychological↗
PubMed1999

Calcium signaling in rat pancreatic acinar cells: a role for Galphaq, Galpha11, and Galpha14.

Stimulus-secretion coupling in the pancreatic acinar cell is initiated by the secretagogues CCK and ACh and results in the secretion by exocytosis of the contents of zymogen granules. A key event in this pathway is the G protein-activated production of second messengers and the subsequent elevation of cytosolic-free Ca2+. The aim of this study was therefore to define the heterotrimeric G protein alpha-subunits present and participating in this pathway in rat pancreatic acinar cells. RT-PCR products were amplified from pancreatic acinar cell mRNA with primers specific for Galphaq, Galpha11, and Galpha14 but were not amplified with primers specific for Galpha15. The sequences of these PCR products confirmed them to be portions of the rat homologues of Galphaq, Galpha11, and Galpha14. The pancreatic-derived cell line AR42J similarly expressed Galphaq, Galpha11, and Galpha14; however, the Chinese hamster ovary (CHO) cell line only expressed Galpha11 and Galphaq. These data indicate that caution should be exercised when comparing signal transduction pathways between different cell types. The expression of these proteins in acinar cells was confirmed by immunoblotting samples of acinar membrane protein using specific antisera to the individual G protein alpha-subunits. The role of these proteins in Ca2+ signaling events was investigated by microinjecting a neutralizing antibody directed against a homologous sequence in Galphaq, Galpha11, and Galpha14 into acinar cells and CHO cells. Ca2+ signaling was inhibited in acinar cells and receptor-bearing CHO cells in response to both physiological and supermaximal concentrations of agonists. The inhibition was >75% in both cell types. These data indicate a role for Galphaq and/or Galpha11 in intracellular Ca2+ concentration signaling in CHO cells, and in addition to Galphaq and Galpha11, Galpha14 may also fulfill this role in rat pancreatic acinar cells.

Animals↗
PubMed1997

Heterotrimeric G-protein Gq/11 localized on pancreatic zymogen granules is involved in calcium-regulated amylase secretion.

The heterotrimeric G-protein Gq/11 was identified on pancreatic acinar zymogen granules and its function in calcium-regulated exocytosis was examined. Western blotting showed alphaq/11, but not alphas or alphao, to be localized to the zymogen granule membrane along with G-protein beta-subunit; all three alpha subunits were present in a plasma membrane fraction and the alphaq/11 signal was 30-fold more enriched in the plasma membrane as compared with granule membrane. Neither CCK receptors nor alpha subunits of the sodium pump, both plasma membrane markers were present on granule membranes. Immunohistochemistry of pancreatic lobules showed that alphaq/11 localized to the zymogen granule-rich apical region of acinar cells together with a much stronger signal at the basolateral plasma membrane. When the substance-P-related peptide GPAnt-2a, an antagonist of Gq/11, was introduced into streptolysin-O permeabilized acini to bypass the plasma membrane, the amylase release induced by 10 microM free calcium was potentiated in a concentration-dependent manner. By contrast, another substance-P-related peptide, GPAnt-1, an antagonist of Go and Gi, showed no effect on calcium-induced amylase release from permeabilized acini. GPAnt-2a peptide also exerted an inhibitory effect on the total GTPase activity of the purified zymogen granules and a larger inhibitory effect on the GTPase activity of the Gq/11 protein immunopurified from zymogen granules. GPAnt-1, however, did not inhibit GTPase activity of either zymogen granules or immunopurified Gq/11. These results suggest that GPAnt-2a peptide augmented calcium-induced amylase release from permeabilized acini by inhibiting GTPase activity of the Gq/11 protein on zymogen granules. We conclude that Gq/11 protein on zymogen granules plays a tonic inhibitory role in calcium-regulated amylase secretion from pancreatic acini.

Amylases↗
PubMed1997

Processor quality control in laser imaging systems.

Sensitometric techniques for performing processor quality control in laser imaging systems are analyzed in this study. The sensitivity of conventional x-ray films using simulated screen-light sensitometry is compared with helium-neon (HeNe) laser film exposed with a simulated red-light sensitometer, a standalone (reference) laser sensitometer, an experimental (unstable) laser sensitometer, and laser printers. Infrared (IR) laser film exposed with an IR laser diode and a simulated IR sensitometer are also evaluated. It is demonstrated that laser-generated step tablets provide an easy and reliable method of performing laser film processor quality control.

Helium↗
PubMed1994

Method of simulated screen sensitometry for asymmetric, low crossover medical x-ray films.

Recognition of the importance of performing simulated screen-light sensitometry of medical x-ray films for the purpose of processor quality control has increased over the past several years. As a result there is a greater need to provide new techniques for performing simulated screen-light sensitometry. Medical films with reduced intensifying screen-light crossover intended to achieve reduced blur and higher spatial resolution pose particular problems in doing simulated screen-light sensitometry if care is not taken to choose a proper simulated light sensitometer with the capability of simultaneous double-sided exposures. Misleading and incorrect sensitometric data can be obtained for film contrast evaluation if a single side exposure is used. Asymmetric, near-zero crossover films pose even greater problems as proper orientation of the film and proper degree of light output asymmetry need be achieved in order to obtain correct sensitometry. The films used in this study were three double emulsion films varying in crossover from 3% to 24%. Of the two very-low-crossover films, one had symmetric emulsion layers while the second featured emulsion layers which were asymmetric in terms of contrast and speed. Sensitometric data show several curve shapes with significant distortions, depending on orientation, for the asymmetric, low-crossover film when exposed using a single-sided exposure. Only by using a double-sided exposure and an appropriate neutral density filter to simulate the degree of screen-light asymmetry in this system could one achieve a characteristic curve comparable to that achieved by inverse square sensitometry.

Biophysical Phenomena↗
PubMedDate not supplied

Body mass index, eating attitudes, and symptoms of depression and anxiety in pregnancy and the postpartum period.

OBJECTIVE: This report describes associations between body mass index (BMI; kg/m2), eating attitudes, and affective symptoms across pregnancy and the postpartum period in a sample of 64 women. METHODS: As part of a larger study, women were recruited during pregnancy and followed prospectively to 14 months postpartum. Measures included self-reported prepregnancy and 4-month postpartum BMI as well as pregnancy, 4-month, and 14-month postpartum eating attitudes (EAT), depressive symptoms (CES-D), and anxiety symptoms (STAI). RESULTS: During pregnancy, symptoms of depression or anxiety were not significantly correlated with concurrent eating attitudes or measures of BMI. However, at 14 months postpartum, measures of eating attitudes and both depression and anxiety symptoms were associated. Measures of BMI were associated with depressive and anxiety symptoms at both 4 and 14 months postpartum. Four-month eating attitudes and BMI predicted 14-month postpartum depressive symptoms, beyond pregnancy, and 4-month postpartum measures of affective symptoms. Results suggested that overweight women were at risk for elevated anxiety at 4 months and depressive symptoms at both 4 and 14 months postpartum. CONCLUSIONS: These results provide evidence for a significant, albeit moderate, relationship between BMI, eating attitudes, and symptoms of depression and anxiety in the postpartum period that are not present during pregnancy.

Adult↗