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Biomedical subjects

J S Roberts

Publications and source records attributed to J S Roberts.

At least 19 recordsLinked to original sources
PubMed1995

Pregnancy, lactation, and menopause: how physiology and gender affect the toxicity of chemicals.

We explore ways in which biological events and nonbiological gender factors in women's lives can mediate the toxicity of chemicals to women. We examine the physiologic changes that accompany pregnancy, lactation, and menopause in order to discuss how these changes might influence the target organ dose and distribution of toxic chemicals within women's bodies. We suggest that the interactions between divalent metals and calcium metabolism and those between lipophilic chemicals and fat metabolism could modulate the toxicity of metallic and lipophilic toxins in women over the course of a lifetime. These hypotheses need careful research consideration.

Drug-Related Side Effects and Adverse Reactions↗
PubMed1990

Influenza vaccine and anticoagulation control in patients receiving warfarin.

The effects of a trivalent split virion influenza vaccine on anticoagulation control were prospectively evaluated in a sample of well-controlled warfarin recipients. Vaccine-induced changes in prothrombin time ratios were not detected during one month of follow-up after immunisation. The results are supported by the findings of other studies conducted in this country and the USA, which have all refuted the conclusions of early reports that suggested a possible interaction between warfarin and influenza vaccine.

Aged↗
PubMed1989

An evaluation of measles, mumps and rubella vaccine in a population of Yorkshire infants.

In October 1988 combined measles, mumps and rubella (MMR) vaccination replaced monocomponent measles as part of the routine childhood vaccination programme in the United Kingdom. Prior to this policy change a study was undertaken in 335 children aged 15 months, to evaluate the clinical reactions and immunogenicity of the new combined MMR vaccine (Trimovax, Immravax, Merieux), in comparison with an established monocomponent measles vaccine (Rouvax, Merieux). Parents were asked to select whether their child should receive MMR vaccine or measles monocomponent; over 95% chose MMR. Children who were given the MMR vaccine had seroconversion rates of 96% for measles, 97% for mumps and 100% for rubella, whilst those who received monocomponent measles vaccine had a seroconversion rate of 100%. The number of side effects reported was similar with both vaccines; all were mild and self-limiting. The results from this study confirm the efficacy and low reactogenicity of MMR vaccine and support its use as part of the routine childhood immunisation programme in the United Kingdom.

Female↗
PubMed1989

Phenotypic heterogeneity of spontaneous lymphomas of CWD mice.

Animals of the inbred mouse strain, CWD, express endogenous murine leukemia viruses early in life and have a high incidence of spontaneous neoplasms. We found that approximately one half of these animals died of malignant lymphoma by the age of 16 months. Splenic enlargement was seen in all mice, but thymic involvement was unusual. One half of the CWD tumors were diffuse lymphoblastic or immunoblastic lymphomas while the remainder were large cell, small cell, or mixed cell lymphomas. Analysis of DNAs from 12 tumors for immunoglobulin and T-cell receptor gene rearrangements revealed that all six of the lymphoblastic and immunoblastic lymphomas were of T-cell origin, as was one tumor of small cleaved cells. Four of the others were clonal B-cell lymphomas and one was of uncertain lineage. Assays of a limited number of tumors for the expression of the Thy 1.2 and IgM molecules confirmed the diversity in the cellular phenotype. The results indicate that CWD mice develop primarily splenic lymphomas with an unusual degree of heterogeneity in the tumor cell phenotypes as compared with the thymic lymphomas found in other high leukemia strains. The CWD strain is a useful new model for studies of retroviral leukemogenesis and the relationship between the histopathology and immunophenotype of malignant lymphomas.

Animals↗
PubMed1989

Tuberculin testing: comparison of imotest with Heaf and Mantoux.

Immunisation against tuberculosis is still recommended for secondary school children in the UK. Only children who do not react to tuberculin tests are offered vaccination. We report the results of two studies, carried out to evaluate a new applicator of the disposable Imotest multiple puncture tuberculin test. The results demonstrate that Imotest is well tolerated and compares favourably with the Heaf and Mantoux tests. Imotest detected significantly more tuberculin responders than Heaf.

Child↗
PubMed1988

Mechanism of selection of class II recombinant murine leukemia viruses in the highly leukemic strain CWD.

The development of spontaneous lymphomas in CWD mice is associated with the expression of endogenous ecotropic murine leukemia viruses (MuLV) and the formation of recombinant viruses. However, the pattern of substitution of nonecotropic sequences within the envelope genes of the CWD class II recombinant viruses differs from that seen in class I recombinant MuLVs of AKR, C58, and HRS mice. To determine how CWD host genes might influence the envelope gene structure of the recombinant viruses, we characterized the responses of these mice to two different types of exogenous MuLVs. Neonatal mice injected the HRS class I recombinant PTV-1 became infected and developed T-cell lymphomas more rapidly than controls did. The inoculation of CWD mice with the leukemogenic AKR ecotropic virus SL3-3 led to the formation of recombinant MuLVs with a novel genetic structure and class II-like envelope genes, although SL3-3 generates class I recombinants in other strains. These results suggest that the absence of class I recombinant MuLVs in CWD mice is not related to the restriction of the replication or oncogenicity of class I viruses or to the absence of an appropriate ecotropic virus that can generate class I recombinants. More likely, the genes of CWD mice that direct the formation or selection of class II recombinant viruses affect the process of recombination between the ecotropic and nonecotropic envelope gene sequences.

Animals↗
PubMed1988

Privilege delineation in a demanding new environment.

The delineation of clinical privileges is one of the most important means for hospitals to ensure high-quality care. Competition, cost control, and public accountability have created the need for hospitals to assure effective privilege delineation processes. Hospitals should focus on issues of practice variation, continuity of care, volume of services provided and planned, and the integration of ethical considerations into clinical decisions. How information is obtained, verified, and acted upon is reviewed within the organizational framework of the hospital. Several leaders within the hospital, such as the clinical department chairs and members of the medical staff executive committee, have important functions in the clinical privilege delineation process. Granting clinical privileges is a critical hospital function that requires a commitment by the governing body, management, and medical staff leaders.

Clinical Competence↗
PubMed1985

Effect of energy intake on the promotion of mammary carcinogenesis by dietary fat.

The effect of low-fat and high-fat diets on the induction of mammary carcinomas by 1-methyl-1-nitrosourea (MNU) was studied in female Sprague-Dawley rats. All rats were given MNU (25 mg/kg body wt) at 50 days of age. For the first 17 weeks after carcinogen administration, they were fed a purified diet containing either 5 or 20% fat incorporated into agar gel. Food intake was restricted, so that the amounts fed provided the same amount of net utilizable energy each day for both groups, regardless of the fat content of the diets. From 17 to 32 weeks, the diets were fed ad libitum. During the restricted feeding period, there was no significant difference in tumor incidence or in the number of tumors detected between the groups. During the weeks in which animals were fed ad libitum, significantly more tumors appeared in the high-fat group than in the low-fat group. The data provide support for the hypothesis that consumption of a high-fat diet can lead to an enhancement of mammary carcinogenesis. It appears, however, that diets must be consumed ad libitum for the stimulatory effect on tumor occurrence to be exhibited.

Animals↗
PubMed1982

Effects of early cold adaptation on food efficiency and dietary-induced thermogenesis in the adult rat.

The food intakes of male and female rats (Harvard strain) adapted to cold (5 degrees C) starting at weaning were studied in the cold and during reacclimation to 25 degrees C. Following 24 hr food deprivation, the male rats regained the weight they had lost without making up for the food they had missed (increased food efficiency), while the female rats ate 75% more food than they had missed in regaining their body weights (decreased food efficiency), independent of the temperature at which the animals were housed. On a high fat diet, both cold groups gained less weight than did the two control groups. However, each female group gained significantly less weight than its same temperature male group. Dietary-induced thermogenesis was significantly enhanced in male cold adapted rats 3 months after reacclimation to the zone of thermal neutrality but not in cold adapted female rats. Sex and strain differences are discussed. These data indicate that early chronic cold exposure results in both immediate and long-term changes in food efficiency and metabolism in adult rats, but the effects vary with the sex of the animal.

Acclimatization↗