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Biomedical subjects

J Roberts

Publications and source records attributed to J Roberts.

At least 505 records · Page 28Linked to original sources
PubMed1986

Influence of reduced concentration of L-glutamine on growth and viability of cells in monolayer, in spheroids, and in experimental tumours.

L-Glutamine is a requirement for many cells in tissue culture, an intermediate in many metabolic pathways, and an alternative substrate to glucose for energy metabolism. These properties suggest that glutamine concentration might be a determinant of cell viability in tumours, especially in regions that are deficient in other metabolites. We have therefore studied the effects of glutamine depletion on single cells in culture, on spheroids and on experimental tumours. Absence of glutamine suppressed the growth rate of two cell lines, but cells cultured for up to 6 h in the absence of glutamine had no decrease in plating efficiency. There was little effect on growth of MGH-U1 (human bladder cancer) spheroids of varying the glutamine concentration in the range of 0.1 to 2 mM and spheroids exposed to these concentrations did not develop central necrosis. Lower concentration of glutamine suppressed the rate of spheroid growth, and spheroids did not grow in the absence of glutamine. Pseudomonas 7A glutaminase reduced the survival of cells in glutamine-free culture and prevented growth of spheroids. Glutaminase was injected into mice bearing experimental tumours to reduce blood levels of glutamine; some animals also received 15 Gy radiation to their tumours to assess the effects of glutamine levels on surviving nutrient-deprived (i.e. hypoxic) cells. Glutaminase had no effect on cell survival in the Lewis lung tumour or in MGH-U1 xenografts, with or without radiation; glutaminase caused dose-dependent growth delay of the KHT tumour, which was additive to that caused by radiation. The present results suggest that (i) short-term changes of glutamine concentration have small effects on cell viability; and (ii) depletion of glutamine levels in blood through the in vivo use of glutaminase is unlikely to produce major therapeutic effects against nutrient-deprived cells in solid tumours.

Animals↗
PubMed1986

Excessive daytime sleepiness and the pathophysiology of narcolepsy-cataplexy: a laboratory perspective.

The main disabling symptom of narcolepsy-cataplexy is shown to be the unrelenting excessive daytime sleepiness (EDS) based upon controlled studies of socioeconomic effects and the poor response to treatment. Objective performance deficits mainly involve tests of ability to sustain performance on repetitive boring tasks and are reversible by improved alertness. Physiologically, EDS is seen to represent relatively slow waxing and waning of alertness rather than punctate microsleeps. Evidence is provided for complex cerebral evoked potentials (P300, contingent negative variation) being very sensitive EDS measures comparable to the multiple sleep latency test (MSLT). EDS appears to have qualitatively somewhat different forms mainly reflecting pressure for REM sleep (REM sleepiness) or pressure for NREM sleep (NREM sleepiness), which have different effects on cerebral evoked potentials as well as subjective and objective (MSLT) differences. It is argued that in pathophysiological terms narcolepsy may best be considered a disease of state boundary control.

Cataplexy↗
PubMed1986

Parenteral nutrition in obstetrics and gynecology.

Parenteral nutrition is required to maintain and restore an anabolic state when oral or enteral routes are not feasible. Despite 16 years of parenteral nutrition availability, reports about parenteral therapy in gynecologic patients or during pregnancy have not been published until relatively recently. Most information is anecdotal but suggests that this mode of therapy is safe, effective, and occasionally life-saving. Parenteral nutrition is used most commonly in women with gynecologic malignancies who are unable to obtain adequate nourishment either during or after surgery, radiation, or chemotherapy. Parenteral alimentation during pregnancy has been used mostly to provide adequate nutrition for those who suffer from prolonged hyperemesis or when there is difficulty in absorption of adequate nutrients. The proper selection and administration of dextrose, fat, protein, vitamins, trace elements, and electrolytes for pregnant women has been associated with apparent favorable perinatal outcomes. Preterm deliveries and intrauterine fetal growth retardation are relatively common and relate to the preexisting or a coexisting medical or obstetric complication. Nutritional assessment before therapy should include a detailed diet history and establishment of baseline clinical and laboratory parameters. Oral or enteral feedings should be attempted beforehand if possible to conserve high costs and potential complications. Parenteral requirements are extrapolated from recommended daily allowances for oral intake, allowing for adjustments in variable absorption. Standardized formulations and fat emulsions are available at pharmacies in many hospitals, making ordering of complex solutions easier, more efficient, and cost effective. Metabolic and septic complications occur infrequently with close monitoring. Few women require intravenous therapy for very long, and home parenteral nutrition is rarely necessary.

Adolescent↗
PubMed1986

Immunosuppression following alloantigen exposure: a role for lymphocyte Fc gamma-receptor blocking antibodies.

In this study we have shown that IgG class, noncytotoxic, Fc gamma-receptor blocking antilymphocyte antibodies can de detected in a high proportion of patients who have previously been exposed to alloantigens, i.e. multiple transfused uraemic patients, haemophiliacs and male homosexuals. These antilymphocyte antibodies appear to cross-react with human spermatozoa. Monomeric IgG preparations from these patients were also found to significantly impair T-cell responsiveness in vitro. Depression of cell mediated immunity by these antibodies may contribute to prolonged graft survival in uraemic patients but may also predispose to infection.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Effects of aging at the adrenergic cardiac neuroeffector junction.

Adrenergic neural degeneration was seen to increase with age. This is thought to contribute to the decreased cardiac content of the transmitter. Pharmacologically, it was found with the use of tyramine that virtually all of the norepinephrine (NE) pool is available for release, and that there is no difference in the amount of NE released in relation to age. Cardiac responsiveness to adrenergic agonists decreases with age. Our results suggest that this is caused in great measure by increased activity of the prejunctional, neuronal uptake mechanism in the older animal.

Aging↗
PubMed1985

[13N]Ammonia and L-[amide-13N]glutamine metabolism in glutaminase-sensitive and glutaminase-resistant murine tumors.

The short-term metabolic fate of labeled nitrogen derived from [13N]ammonia or from L-[amide-13N]glutamine was determined in murine tumors known to be resistant (Ridgeway Osteogenic Sarcoma (ROS] or sensitive (Sarcoma-180 (S-180)) to glutaminase therapy. At 5 min after intraperitoneal injection of [13N]ammonia or of L-[amide-13N]glutamine, only about 0.7% of the label recovered in both tumors was in protein and nucleic acid. After [13N]ammonia administration, most of the label (over 80%) was in a metabolized form; a large portion of this metabolized label (50-57%) was in the urea fraction with a smaller amount in glutamine (37-42%). The major short-term fate of label derived from L-[amide-13N]glutamine was incorporation into components of the urea cycle with smaller amounts in the acidic metabolites and in acidic amino acids. No labeled urea was found during in vitro studies in which S-180 tumor slices were incubated with [13N]ammonia, suggesting that the [13N]urea formed in the tumor in the in vivo experiments was not due to de novo synthesis through carbamyl phosphate in the tumor. Both tumors exhibited very low glutamine synthetase activity. Following glutaminase treatment, glutamine synthetase and gamma-glutamyltransferase activities, while remaining low, increased in the resistant tumor but not in the sensitive tumor; this increase may be related to the insensitivity of the ROS tumor toward glutaminase treatment.

Amino Acids↗
PubMed1985

Animal rights.

Explore the source record for details and available documents.

Animals↗
PubMed1985

Prevalence of dermatologic disease in the United States: a review of the National Health and Nutrition Examination Survey, 1971-1974.

The National Health and Nutrition Examination Survey, 1971-1974, provides the only data on the prevalence of dermatologic disease in the United States. Details are given about specific diagnoses, disability, disfigurement, discomfort, and the relationship of skin change to environmental and occupational exposure. One-third of the individuals, which extrapolates to 60 million Americans, had dermatological problems that should have been seen at least once by a physician. Of those, at least a third considered their skin problems to be a handicap, 10% a handicap to employment or housework. These data provide a basis for evaluating the effect of environment and occupation and should be of interest to those concerned with chronic effects of mechanical injury to the skin.

Adolescent↗
PubMed1985

Multiple primary cancers of the respiratory tract: a case of synchronous carcinoma of the larynx, carcinoma of the floor of the mouth, and dual primary bronchogenic carcinomas.

Multiple primary cancers of the respiratory tract are no longer considered uncommon. We describe a patient with synchronous carcinoma of the larynx, carcinoma of the floor of the mouth, and dual primary bronchogenic carcinomas. The clinical presentation, course, and treatment of this condition are discussed. Clinicians should be aware that multiple primary cancers of the respiratory tract are being reported more frequently and any tumor of this area demands a detailed examination of the entire tract at the time of diagnosis and careful, regular follow-up.

Adenocarcinoma↗
PubMed1985

Taking the center to market.

Community mental health centers have seldom been involved in marketing their services. Marketing is defined as responding sensitively to human needs, not hucksterism, and is an appropriate activity for centers. Centers are vulnerable because of declining federal funding and in order to serve the poor, must also service other populations with greater ability to pay for services or face retrenchment. Over the past twenty years, locally controlled centers have broadened their missions to serve many types of personal and family problems, not just the chronically ill. Centers should omit "mental health" for their names because of the stigma. Guidelines for creation of a positive image including name and logo selection, color, open houses, and ad campaigns are given using Madison Center (formerly the Mental Health Center of St. Joseph County) as a case study. Reactions of other providers, creative delivery of services through consultation and education, market segmentation and message levels of advertising are also discussed.

Advertising↗
PubMed1985

An integrative model of cash collections for mental health centers.

Little has been published regarding Community Mental Health Centers and the collection of fees from clients. As centers of the 1980s have faced a sudden decrease in government funding, an effective system of cash collections has become paramount. Many locally-controlled centers have changed their mission to serving a broad spectrum of people with personal problems as well as the chronically mentally ill. This paper documents a system used by a midwestern center resulting in a 230% increase in client fee collections over four years. An integrative model describes collections assessment, developing an accountability system, basic principles of collections, fee setting and client mix. The ability to serve the poor, chronically mentally ill in the future will depend on the ability to serve the broader population of a community.

Accounting↗
PubMed1985

Immune complexes in the acquired immunodeficiency syndrome (AIDS): relationship to disease manifestation, risk group, and immunologic defect.

Immune complex assays (and other immunologic tests) were performed on sera from 162 patients with the acquired immunodeficiency syndrome (AIDS) and 275 AIDS-related subjects. Immune complexes were detected in 89% of AIDS patients and 93% of homosexual men with lymphadenopathy. Immune complex levels in AIDS patients were not associated with a particular risk group or with types of opportunistic infection or malignancy; however, they correlated with other laboratory features of the immune defect (depression in T helper cells and T helper/suppressor-cell ratio, and IgG levels). Immune complexes were also detected in a lesser proportion of risk-group controls (homosexual men, hemophiliacs, Haitians). In risk-group controls, immune complex levels were associated with certain features reflecting sexual practice, blood product exposure, or infection, but these features did not account for the higher levels found in AIDS patients. In appropriate situations, immune complex assays may be of value as screening tests or, possibly, as prognostic indicators for AIDS or AIDS-related syndromes.

Acquired Immunodeficiency Syndrome↗
PubMed1985

A colorimetric assay of pancreatic lipase: rapid detection of lipase and colipase separated by gel filtration.

A rapid assay for pancreatic lipase (E.C., glycerol-ester hydrolase 3.1.1.3) is described. The assay is based on the color change of a pH indicator as butyric acid is released from the substrate tributyrin. A mixture made with tributyrin and the water soluble components of the assay is ideally suited for use as a rapid test as, for example, when assaying chromatography fractions. Quantitative data can be obtained by measuring the disappearance of absorbance at 557 nm versus a blank reaction. The assay has been used in the rapid preparation of colipase-free lipase and colipase.

Chromatography, Gel↗