Endotoxin, coliform, and dust levels in various types of rodent bedding

Endotoxins in grain dust, household dust, and animal bedding may induce respiratory symptoms in rodents and humans. We assayed the endotoxin, coliform, and dust levels in 20 types of rodent bedding. Endotoxin concentrations were measured by using a commercial test kit, coliform counts were determined by using conventional microbiologic procedures, and dust content was evaluated by using a rotating-tapping shaker. Paper bedding types contained significantly less endotoxin than did other bedding types; the highest levels of endotoxin were detected in hardwood and corncob beddings. The range of endotoxin content for each bedding type was: corncob bedding, 1913 to 4504 endotoxin units per gram (EU/g); hardwood bedding, 3121 to 5401 EU/g; corncob-paper mixed bedding, 1586 to 2416 EU/g; and paper bedding, less than 5 to 105 EU/g. Coliform counts varied from less than 10 to 7591 cfu/g in corncob beddings, 90 to 4010 cfu/g in corncob-paper mixed beddings, less than 10 to 137 cfu/g in hardwood beddings, and less than 10 cfu/g in paper beddings. Average dust content was less than 0.15% in all commercial bedding types. We conclude that paper bedding is the optimal bedding type for conducting LPS inhalation studies and that rodent bedding containing high levels of endotoxin may alter the results of respiratory and immunologic studies in rodents.

Dietary factors affecting uterine weights of immature CD-1 mice used in uterotrophic bioassays

A study was conducted to determine the effects of dietary factors in natural ingredient and purified diets on uterine weights of immature CD-1 mice used in uterotrophic bioassays. Factors evaluated included body weight gain, dietary phytoestrogen content, total metabolizable energy, and percent crude fiber. Fifteen to 147 mice per group, housed 5 per cage, were randomly assigned to each of the 20 test diets. The test diets were fed for 7 days to 15-day old immature female CD-1 mice and their body weight gain and uterine weights were determined. Analysis of covariance procedures were used to evaluate differences in uterine weights, after adjusting for body weight and time-related trends. Fisher's least significant difference test was used to compare adjusted uterine weights and weight gains among the test diets. Additionally, multiple linear regression procedures were used to identify those characteristics of the rodent diet that were most predictive of the adjusted uterine weights. Total metabolizable energy was significantly (P < 0.01) correlated with and was predictive of uterine weights. The following dietary variables were not significantly predictive of uterine weights: total daidzein and genistein content, percent protein, fat, N-FE (carbohydrates) or percent crude fiber. We concluded that: (1) total metabolizable energy (ME) in natural ingredient or purified diets has a significant (P < 0.01) effect on the uterine weights of immature mice used in 7-day uterotrophic bioassays; (2) a standardized, estrogen-free diet with a constant level of ME should be used for conducting uterotrophic assays when comparing results between different laboratories or when determining the estrogenic or anti-estrogenic activity of endocrine disruptor compounds; (3) the mouse uterotrophic assay remains a sensitive bioassay for assessing chemicals for estrogenic activity or for the detection of total estrogenic activity in rodent diets that may be contaminated with estrogenic compounds, and (4) chemical assays should be used to detect or measure low levels of the phytoestrogens in rodent diets.

Evolution of Fermi-liquid interactions in Sr2RuO4 under pressure

We have measured the temperature and field dependence of the resistivity of the unconventional superconductor Sr2RuO4 at pressures up to 3.3 GPa. Using the Shubnikov-de Haas effect, we find that the Fermi surface sheet believed to be primarily responsible for superconductivity becomes more two-dimensional with increasing pressure, a surprising result that is, however, consistent with a recent model of orbital-dependent superconductivity in this system. Many-body enhancements and the superconducting transition temperature all fall gradually with increasing pressure, contrary to previous suggestions of a ferromagnetic quantum critical point at approximately 3 GPa.

Extragonadal teratocarcinoma in chimeric mice

Chimeric mice often are created through the genetic manipulation of the mouse embryo in the process of developing animal models of disease. These mice have variable percentages of their somatic and germ cells derived from the donor embryonic stem cells and host blastocysts. In the development of mouse models deficient in the breast cancer susceptibility gene 2 (Brca2) or the 70-kd heat shock protein (Hsp70-2), 3-4-week-old chimeras developed single or multiple masses composed of both well-differentiated and poorly differentiated tissues derived from all three germ layers. These cases of extragonadal teratocarcinoma, a rarely reported tumor, may be related to the genetic predisposition of the 129/Ola mouse strain used to generate the embryonic stem cells.

Ganglioneuroma in the Adrenal Gland of a Rat

Necropsy was performed on a 22-month-old male Fischer 344 rat (Rattus norvegicus) that had weight loss and was icteric. Examination revealed a large, smooth, circumscribed, tan mass located at the cranial border of the right kidney. Microscopically, the mass consisted almost entirely of well-differentiated ganglion cells mixed with satellite and Schwann cells within a neurofibrillar matrix. The cells displaced the adrenal medulla and were partially surrounded by a thin rim of compressed adrenal cortex. Focal areas of hemorrhage and infiltrates of leukemic mononuclear cells were evident throughout the mass, but pheochromocytes were not detected. On the basis of findings during histologic examination, a diagnosis of adrenal medullary ganglioneuroma was made. Mononuclear cell leukemia was also diagnosed in the adrenal gland and was evident in lymphoid organs such as the spleen and mesenteric lymph nodes. Ganglioneuroma is rarely seen in rats and can be differentiated from more common complex pheochromocytomas, which consist of fewer neural components (< 80% of the mass). In rats, ganglioneuromas can develop in the central nervous system, pituitary gland, and thyroid gland. Differential diagnoses for a primary neoplasm of the adrenal gland should include carcinomas and adenomas of the adrenal cortex, and pheochromocytomas, neuroblastomas, and ganglioneuromas of the adrenal medulla.

An anthropologist's viewpoint: observations and commentary regarding "Implementation of nursing vocabularies in computer-based systems"

Those who work in the area of vocabularies, like all researchers, bring some assumptions to that work. Such assumptions include both cultural notions and beliefs specific to particular social worlds within the broader society. In this article, assumptions and beliefs expressed by participants during the conference on "Implementation of Nursing Vocabularies in Computer-based Systems" are summarized. Questions are raised concerning the relationship between cultural notions and beliefs and nursing vocabularies.

Involving patients in health care: explanation in the clinical setting

The long-term goal of our research is to improve the overall effectiveness of physicians' time, by improving the information exchange between physicians and chronic-care patients, initially migraine patients. The computer system we are constructing has a partial knowledge base about migraines, common therapies, and common side effects of those therapies. The system consists of two main programs: data collection and explanation. The design of our system is based on empirical data concerning patients' information needs.