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Biomedical subjects

C Cheng

Publications and source records attributed to C Cheng.

210 records · Page 12Linked to original sources

Applications and mechanisms of charge-remote fragmentation.

Studies on the applications, energetics, and mechanisms of charge-remote fragmentations are reviewed, with emphasis given to those articles published after 1992. Independent of the charge status, charge-remote fragmentations are analogous to gas-phase thermolysis. Under collisional activation and with a fixed charge, ions containing long-chain or poly-ring structures undergo charge-remote fragmentations, generating productions that are structurally informative. Interpretation of the production spectra enables one to elucidate molecular structures. Although charge-remote fragmentations have been successfully used in the structural determination of fatty acids, phospholipids, glycolipids, triacylglycerols, steroids, peptides, ceramides, and other systems, the energetics and mechanisms of these reactions are still debated because none of the existing mechanisms can explain all the experimental data.

Ceramides↗

Expression profiles of 50 xenobiotic transporter genes in humans and pre-clinical species: a resource for investigations into drug disposition.

Carrier-mediated transporters play a critical role in xenobiotic disposition and transporter research is complicated by species differences and their selective tissue expression. The purpose of this study was to generate a comprehensive data set of xenobiotic transporter gene expression profiles in humans and the pre-clinical species mouse, rat, beagle dog and cynomolgus monkey. mRNA expression profiles of 50 genes from the ABC, SLC and SLCO transporter superfamilies were examined in 40 human tissues by microarray analyses. Transporter genes that were identified as enriched in the liver or kidney, or that were selected for their known roles in xenobiotic disposition, were then compared in 22 tissues across the five species. Finally, as clinical variability in drug response and adverse reactions may be the result of variability in transporter gene expression, variability in the expression of selected transporter genes in 75 human liver donors were examined and compared with the highly variable drug metabolizing enzyme CYP3A4.

Animals↗

Determinants of fertility decline in China, 1981: analysis of intermediate variables.

This study examines the proximate determinants of fertility in China by making use of the data collected by the One-per-Thousand Sample Fertility Survey of 1982. The results indicate that the most important inhibitor of potential fertility is deliberate control. Its contribution to fertility change has been far greater than all other proximate determinants. The marital structure of the population is also an important factor, while lactational infecundability and induced abortion are relatively unimportant. Comparative results by using data from the In-depth Fertility Survey conducted in Shanghai Municipality, Hebei and Shaanxi Provinces in April 1985 agree well in the ranking of the four intermediate factors. The findings point to successful family planning program and government population policies, which propelled the fertility transition to a substantial degree. Further research needs and policy implications of the results of the study are discussed.

Adolescent↗

Coping style of individuals with functional dyspepsia.

OBJECTIVES: The objectives of the study described here were to 1) examine the coping style of patients with functional dyspepsia (FD) and 2) adopt a new interview questionnaire to examine the extent of discriminativeness in the use of coping strategies across different stressful situations. METHODS: A matched case-control design was adopted to compare differences among a target group of 30 patients with FD, a pain control group of 30 patients with rheumatism, and a control group of 30 healthy persons. A new interview questionnaire, the Coping Flexibility Interview Schedule, was used to assess subjects' experience of stressful life events, use of coping strategies, and perceived severity of major FD symptoms. RESULTS: Subjects with FD perceived their experienced stressors as more uncontrollable and as having a greater impact (p < .05). They also used more direct-action strategies but fewer divert attention, acceptance, social support, and relaxation strategies when handling stressful life events (p < .05). A significant group-by-controllability interaction effect was found (p < .001), indicating that FD subjects tended to use coping strategies nondiscriminatively, whereas both rheumatic and healthy subjects tended to use coping strategies more discriminatively across stressful life events of different extents of controllability. CONCLUSIONS: These results indicate that FD patients are characterized by a nondiscriminative, action-oriented coping style. The implications of this finding for the extant body of research and the advantages of using our interview questionnaire, which has a more flexible format, are discussed.

Adaptation, Psychological↗

Seeking medical consultation: perceptual and behavioral characteristics distinguishing consulters and nonconsulters with functional dyspepsia.

OBJECTIVE: Subjects with functional dyspepsia (FD) in most previous studies have been confined to those who sought medical consultation. The generalizability of results from these studies to individuals with FD who do not seek medical consultation is limited. This study examined 1) differences in perceptual and behavioral characteristics between "nonconsulters" and "consulters" with FD and 2) the influence of these characteristics on dyspeptic and psychological symptoms. METHODS: A matched case-control design was used to compare differences among 43 nonconsulters with FD, 43 consulters with FD, and 43 healthy individuals. Subjects' monitoring perceptual style, confrontative coping behaviors, dyspeptic symptoms, anxiety, and depression were assessed by using well-validated questionnaires. RESULTS: FD consulters exhibited higher levels of monitoring, confrontative coping, anxiety, and depression than FD nonconsulters and healthy subjects (p values < .01). Results from discriminant analysis revealed that all these variables reliably predicted the membership of the three groups. Significant Monitoring by Confrontative Coping interaction effects were also found, indicating the conjoint influences of these variables on dyspeptic and psychological symptoms. CONCLUSIONS: These results show that FD nonconsulters are distinguishable from FD consulters by their perceptual style, coping behaviors, and psychological symptoms. Both monitoring perceptual style and confrontative coping behaviors may magnify dyspeptic and psychological symptoms in individuals with FD, especially those who seek medical consultation.

Adaptation, Psychological↗

Total pelvic exenteration: results from a multispecialty team approach to complex cancer surgery.

Total pelvic exenteration is often the only curative option for recurrent or locally advanced pelvic cancers, but it carries a high risk of mortality and morbidity. A dedicated multispecialty team operative approach may provide the expertise to perform this uncommon procedure with favorable outcomes. Data were analyzed from a prospectively collected computerized database. There were 14 patients (2 men; mean age, 54.6 +/- 3.6 years) with mainly cervical cancers, of which 71.4% were recurrent. Anesthetic time was 5 +/- 0.9 hours, intraoperative blood loss was 2.1 +/- 0.5 liters, and postoperative hospitalization was 22 +/- 9.9 days. An ileal conduit was performed in all patients, but intestinal continuity was restorable with colonic J-pouch in 71.4% of the patients. There was no mortality at 30 days or during hospitalization. Complication rates were 35.7%, accounting for reoperations in 28.6%. Recurrences were detected in 50% patients at a mean follow-up of 53.1 +/- 9.2 months. The mean time for cancer recurrence was 13.3 +/- 3.3 months. Fifty percent of those patients had otherwise survived to date. We conclude that a dedicated multispecialty team may perform total pelvic exenteration with minimum mortality and acceptable morbidity.

Adult↗

Evaluation of the BAX system for detection of Listeria monocytogenes in foods: collaborative study.

A multilaboratory study was conducted to compare the automated BAX system and the standard cultural methods for detection of Listeria monocytogenes in foods. Six food types (frankfurters, soft cheese, smoked salmon, raw, ground beef, fresh radishes, and frozen peas) were analyzed by each method. For each food type, 3 inoculation levels were tested: high (average of 2 CFU/g), low (average of 0.2 CFU/g) and uninoculated controls. A total of 25 laboratories representing government and industry participated. Of the 2335 samples analyzed, 1109 were positive by the BAX system and 1115 were positive by the standard method. A Chi square analysis of each of the 6 food types, at the 3 inoculation levels tested, was performed. For all foods, except radishes, the BAX system performed as well as or better than the standard reference methods based on the Chi square results.

Chi-Square Distribution↗