Factors associated with practice of colorectal cancer screening among primary care physicians in a Chinese population: A cross-sectional study

Objectives: Primary care physicians (PCPs) are influential in colorectal cancer (CRC) screening uptake in the community. This study aims to evaluate the factors associated with PCPs’ practice of CRC screening among asymptomatic patients in a Chinese population. Methods: A validated postal questionnaire was sent to all practicing PCPs who were members of a community-based network in Hong Kong. Three separate rounds of reminder letters were sent to non-respondents. Binary logistic regression analysis was used with ever-referral for CRC screening in the past 12 months as the outcome variable. Predictor variables include physicians’ gender, clinical experience, types of practice, and attitudes towards CRC screening. Results: Of 428 eligible physicians, 263 (61.4%) responded. A total of 187 physicians (71.1%) had referred patients for CRC screening in the past 1 year. Among all asymptomatic patients aged 50 years or older, physicians reported referring only 3.0% (1.0–10.0%) [median (interquartile range)] of patients. Colonoscopy (57.0%) and fecal occult blood testing (FOBT) (46.4%) were the most commonly recommended tests for these asymptomatic patients. Family history of CRC (58.6%) and patients’ concern about CRC (50.2%) were major reasons for referral. PCPs in private practice (adjusted odds ratio [aOR] 2.60, 95% C.I. 1.21–5.59) and those with positive attitude towards CRC screening (aOR 2.27, 95% C.I. 1.15–4.48) were more likely to recommend CRC screening. Conclusions: PCPs’ attitude towards CRC screening is a significant determinant of its practice. Future studies should identify and strengthen the influencers of PCPs’ attitude to enhance CRC screening rates.     

Progressive atrophy of the thymus in mice carrying Lewis lung carcinoma grafts

Summary A rapid and progressive thymus atrophy in B₆D₂ mice following transplantation of Lewis lung carcinoma cells is reported. Spleen weight, however, increased in tumor-carrying animals. Tumor extracts failed to induce these alterations. The mechanism of these perturbations of the immune system in tumor-carrying animals is discussed.This work was supported by the Norwegian Cancer Society     

Proton Pump Activity of Mitochondria-rich Cells : The Interpretation of External Proton-concentration Gradients

We have hypothesized that a major role of the apical H⁺-pump in mitochondria-rich (MR) cells of amphibian skin is to energize active uptake of Cl⁻ via an apical Cl⁻/HCO₃ ⁻-exchanger. The activity of the H⁺ pump was studied by monitoring mucosal [H⁺]-profiles with a pH-sensitive microelectrode. With gluconate as mucosal anion, pH adjacent to the cornified cell layer was 0.98 ± 0.07 (mean ± SEM) pH-units below that of the lightly buffered bulk solution (pH = 7.40). The average distance at which the pH-gradient is dissipated was 382 ± 18 μm, corresponding to an estimated “unstirred layer” thickness of 329 ± 29 μm. Mucosal acidification was dependent on serosal pCO₂, and abolished after depression of cellular energy metabolism, confirming that mucosal acidification results from active transport of H⁺. The [H⁺] was practically similar adjacent to all cells and independent of whether the microelectrode tip was positioned near an MR-cell or a principal cell. To evaluate [H⁺]-profiles created by a multitude of MR-cells, a mathematical model is proposed which assumes that the H⁺ distribution is governed by steady diffusion from a number of point sources defining a set of particular solutions to Laplace''s equation. Model calculations predicted that with a physiological density of MR cells, the [H⁺] profile would be governed by so many sources that their individual contributions could not be experimentally resolved. The flux equation was integrated to provide a general mathematical expression for an external standing [H⁺]–gradient in the unstirred layer. This case was treated as free diffusion of protons and proton-loaded buffer molecules carrying away the protons extruded by the pump into the unstirred layer; the expression derived was used for estimating stationary proton-fluxes. The external [H⁺]-gradient depended on the mucosal anion such as to indicate that base (HCO₃ ⁻) is excreted in exchange not only for Cl ⁻, but also for Br⁻ and I⁻, indicating that the active fluxes of these anions can be attributed to mitochondria-rich cells.