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Biomedical subjects

J C Allen

Publications and source records attributed to J C Allen.

At least 343 records · Page 19Linked to original sources
PubMedDate not supplied

Glucocorticoid and polyamine involvement in zinc uptake by COMMA-1D mammary epithelial cells.

The objective was to determine if a mammary cell line shows glucocorticoid stimulation of Zn uptake, and to determine whether polyamines mediate this stimulation. 65Zn uptake by COMMA-1D mouse mammary epithelial cells over a 24-h period increased significantly in cells administered 10(-7) or 10(-6) M hydrocortisone. Incorporation of 65Zn over a 1-h period was not hydrocortisone-responsive, suggesting that these incubation times represent uptake into different pools. The rate of entry into the cells over a 15-min period was significantly increased by supplementing cells with hydrocortisone with or without prolactin. Initially, cells grown in lactogenic hormone-supplemented media (10(-6) M hydrocortisone + 5 micrograms/mL ovine prolactin) had up to 65% greater 65Zn uptake over 24 h than cells in nonsupplemented growth media. 65Zn uptake from hormone media with the spermidine synthesis inhibitor methylglyoxal-bis-(guanylhydrazone) (MGBG, 10(-5)M) added was less than from growth media. Exogenous spermidine (10(-6)-10(-3)M) added to the MGBG + hormone media increased 65Zn uptake. Difluoromethylornithine (DFMO), an inhibitor of spermidine synthesis that blocks ornithine decarboxylase, caused a slight dose-dependent decrease in 65Zn uptake over the range 10(-6)-5 x 10(-3)M (p < 0.002) and tended to decrease 65Zn-uptake in lactogenic hormone-stimulated cells with 8 h of incubation, but not at other times. These data show that Zn uptake in mammary epithelial cells can be hormonally mediated by glucocorticoids and suggest that polyamines may be intracellular mediators of this effect.

Animals↗
PubMedDate not supplied

Can anthropometric measurements and diet analysis serve as useful tools to determine risk factors for insulin-resistant diabetes type 2 among white and black Americans?

OBJECTIVE: Central obesity is implicated in the development of insulin resistance by increasing insulin demand and eventually leading to hyperinsulinemia. Anthropometric measurements have been helpful in determining the risk factors in developing diabetes mellitus type 2. In this study we investigated whether anthropometric measurements differ among diabetics of different races. We also evaluated whether nutrient intake of these individuals was related to anthropometric measurement changes. METHODS: Subjects were recruited from four groups: white control (n = 10), black control (n = 10), white diabetic (n = 5), and black diabetic (n = 10). The diabetic subjects had type 2 diabetes with insulin resistance on insulin monotherapy (age and sex matched). The following determinations were made: diet analysis, body mass index (kg/m(2)), the ratio of waist (umbilical level) to hip (maximum at buttocks) circumference, the ratio of waist to thigh (mid-thigh), and body fat percentage. RESULTS: The micronutrient consumption was fairly similar in all groups with the exception of vitamin A (greatest consumption in the white control group, P < 0.05; and the lowest consumption in the black control group, P < 0.05). The data also suggested that central obesity (greatest waist-to-hip ratio) was present in the individuals with type 2 diabetes. The higher total fat, including saturated, monounsaturated, polyunsaturated, and cholesterol, intake in the diabetic groups were observed. CONCLUSION: The type of fat consumed may be as important as the total fat consumption in the development of insulin resistance. The diet analysis can provide valuable information about the dietary habits of an individual and the possible causes of metabolic problems leading to a disease state. However, genetic factors must be considered when looking at diabetes incidence in different ethnic groups. For example, even though the black diabetic group consumed less fat in comparison with the other groups, their body fat percentages were higher. Therefore, we cannot conclude that high fat intake is primarily responsible for increased body fat percentage. Although anthropometric measurements are a useful tool in risk assessment, researchers should consider anatomic differences among different racial groups as covariables. Diet analysis when used in conjunction with anthropometric measurements can serve as a useful tool to detect whether metabolic alterations are related to dietary habits.

Abdomen↗
PubMedDate not supplied

Brain stem gliomas: a classification system based on magnetic resonance imaging.

MR scans of 87 pediatric patients with brain stem gliomas were retrospectively reviewed to develop a new classification scheme based on MR imaging. The scheme that has been developed utilizes primarily T2-weighted images, as these most accurately show tumor extent. Tumors are characterized as to location of origin, focality, direction and extent of tumor growth, degree of brain stem enlargement, degree of exophytic growth, and presence or absence of cysts, necrosis, hemorrhage, and hydrocephalus. The use of this classification allowed identification of differences in a population of patients who were selected to be as similar as possible. This system will aid in the assessment of new protocols for treatment of brain stem tumors.

Adolescent↗
PubMedDate not supplied

Complications of chemotherapy in patients with brain and spinal cord tumors.

Complications of chemotherapy in pediatric brain tumor patients tend to be acute and short-lived with some special exceptions such as permanent hearing impairment secondary to cisplatin, infertility and an increased risk of second primary neoplasms. Chemotherapy will be better tolerated and probably more effective in brain tumor patients following a major surgical resection, especially when agents such as cisplatin and cyclophosphamide are administered which require intensive intravenous hydration. Neoadjuvant or pre-radiotherapy chemotherapy administration may reduce chemotherapy-related side effects such as leukoencephalopathy secondary to high-dose intravenous methotrexate, neutropenia and thrombocytopenia following intensive chemotherapy, especially when craniospinal radiotherapy is required. The use of bone marrow ablative chemotherapy followed by autologous marrow rescue poses a new spectrum of organ toxicities. New supportive care measures significantly improved tolerance of chemotherapy such as mesna, a drug minimizing hemorrhagic cystitis following ifosfamide, ondonsetron, a highly effective antiemetic, and the hematopoietic growth factors such as G-CSF and GM-CSF which reduce the incidence and severity of symptomatic neutropenia. Chemotherapy may prolong life in patients with recurrent disease and contribute to curative therapy in newly diagnosed patients. The neurooncology community is becoming more familiar with the measures to improve its tolerance and thereby increase its efficacy.

Antineoplastic Agents↗
PubMedDate not supplied

Elucidation of the different effects of polyamines and other naturally-occurring inhibitors of cell proliferation (chalones) on T-lymphocyte and granulocyte colony growth in vitro.

Using T-lymphocyte and granulocyte colony assays with truly proliferating cells the effects of the polyamine spermine and of other naturally-occurring inhibitors of cell proliferation have been differentiated. It has been confirmed that spermine, in the presence of fetal calf serum, is a potent inhibitor of cell proliferation. This inhibition could be reversed by the addition of either 3-hydroxybenzyl-oxyamine or 4-bromo-3-hydroxybenzyl-oxyamine, both of which are inhibitors of the polyamine oxidase. In comparison, fractions isolated from calf thymus were shown to inhibit lymphocyte, but not granulocyte colony growth, indicating their tissue specificity and lymphocyte chalone activity. Further this inhibition was not reversed by polyamine oxidase inhibitors demonstrating that polyamines were not the inhibitory principles in this preparation.

Animals↗
PubMedDate not supplied

Improved enzyme-linked immunosorbent assay for determination of soy protein in meat products.

An indirect, competitive enzyme-linked immunosorbent assay (ELISA) has been developed for quantitation of soy protein in meat products. The methodology allows rapid aqueous extraction of meat samples into a liquid form suitable for assay. The assay is highly specific for soy protein and is designed to measure soy protein levels between 1 and 10% of the wet weight of the sample. Standardized, stabilized reagents for carrying out the procedure are commercially available in a kit. The analysis, including sample preparation, can be completed within a workday, and the actual immunoassay in less than 60 min.

Animals↗
PubMedDate not supplied

Session on malpractice.

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Insurance, Liability↗