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Biomedical subjects

P Barr

Publications and source records attributed to P Barr.

10 recordsLinked to original sources
PubMed1992

The effect of thymidine on the antibacterial and antiviral activity of zidovudine.

The effect of thymidine and deoxyadenosine on the antiviral and antibacterial effect of zidovudine was studied in human immunodeficiency virus type 1 (HIV-1) Escherichia coli and Salmonella typhimurium. In quantitative assays, 10 micrograms mL-1 thymidine was shown to increase the 50% inhibitory concentration (IC50) of zidovudine for HIV-1 by approximately 100-fold and to reduce zidovudine (1 microM)-induced protection of C8166 cells from 2.04 to 0.18 log syncytial-forming units. Thymidine also antagonized the antibacterial effect of zidovudine for two E. coli and three S. typhimurium species in a dose-dependent manner; 10 micrograms mL-1 of thymidine increased the minimum inhibitory concentration of zidovudine for E. coli strains by 10-40-fold and for S. typhimurium strains by three-fold. Deoxyadenosine reduced the minimum inhibitory concentration of zidovudine against all five bacterial strains but had no effect on the IC50 of zidovudine for HIV-1, nor did it significantly reverse the antagonism of the antibacterial and antiviral activity of thymidine. The induction of the SOS response in E. coli was reversed in a dose-dependent manner by thymidine while the presence of deoxyadenosine increased induction of the SOS response by zidovudine at suboptimal concentrations.

Deoxyadenosines↗
PubMed1991

The use of dexamethasone in full-term infants with severe respiratory failure and pulmonary barotrauma.

Eight full-term infants (mean gestation 39.9 weeks [range 37-42] and mean birthweight 3642 g [range 3060-4200]) with severe respiratory failure (median oxygenation index 28 [range 16-65] and median arterial/alveolar PO2 ratio (a/APO2) 0.094 [range 0.038-0.165]) and pulmonary barotrauma were treated with Dexamethasone, 0.5 mg/kg per day, from the median age of 5 days (range 3-22). Six of the eight (75%) infants survived. They were weaned from mechanical ventilation and extubated a median of 2.5 days after commencing treatment with Dexamethasone. Two infants died and one of them suffered recurrent pneumothoraces. There was a significant improvement in oxygenation in the seven infants who survived the 72 h period of observation. Their median oxygenation index was 24 when Dexamethasone was commenced compared with 8 after 12 h (P less than 0.05) and 10 after 36 h (P less than 0.025). Their a/APO2 ratio was 0.095 when Dexamethasone was commenced compared with 0.289 after 12 h (P less than 0.05) and 0.207 after 36 h (P less than 0.025). There was a significant increase in the infants' arterial mean blood pressure associated with Dexamethasone therapy and one infant developed Staphylococcus aureus septicaemia. In this uncontrolled study of eight full-term infants with severe respiratory failure and pulmonary barotrauma, the use of Dexamethasone was associated with significant improvement in oxygenation and rapid weaning from mechanical ventilation.

Barotrauma↗
PubMed1990

Cellular and humoral immune responses to a recombinant P. falciparum CS protein in sporozoite-immunized rodents and human volunteers.

The immune responses of sporozoite-immunized rodents and of human volunteers exposed to multiple bites of irradiated Plasmodium falciparum infected mosquitos have been investigated using a yeast-derived recombinant P. falciparum circumsporozoite (rPfCS) protein. The murine immune response to immunization with rPfCS was not genetically restricted. Nine different murine haplotypes, when immunized with rPfCS, developed high levels of antisporozoite antibodies detectable by IFA and RIA. In addition, injection of rPfCS induced a secondary antibody response in P. falciparum sporozoite-primed mice. Murine T-cell epitopes were mapped in the C terminus of the rPfCS protein using overlapping synthetic peptides. The human T-cell response was investigated using T-cell clones derived from peripheral blood lymphocytes (PBL) of a P. falciparum sporozoite-immunized volunteer. A total of 40 CD4+ T-cell clones were obtained. Stimulation indices ranged from 2.5 to 103.4 following challenge with rPfCS in the presence, but not in the absence, of antigen-presenting cells. The clones were specific for rPfCs and did not proliferate or secrete lymphokines when challenged with yeast-derived recombinant P. vivax or P. berghei CS protein or with a yeast-extract control. The clones also recognized the native CS protein in extracts of P. falciparum, but not P. berghei or P. cynomolgi, sporozoites.

Animals↗
PubMed1989

Conserved repetitive epitope recognized by CD4+ clones from a malaria-immunized volunteer.

T cell clones obtained from a human volunteer immunized with Plasmodium falciparum sporozoites specifically recognized the native circumsporozoite (CS) antigen expressed on P. falciparum sporozoites, as well as bacteria- and yeast-derived recombinant falciparum CS proteins. The response of these CD4+ CD8- cells was species-specific, since the clones did not proliferate or secrete gamma interferon when challenged with sporozoites or recombinant CS proteins of other human, simian, or rodent malarias. The epitope recognized by the sporozoite-specific human T cell clones mapped to the 5' repeat region of the CS protein and was contained in the NANPNVDPNANP sequence.

Amino Acid Sequence↗
PubMed1989

Cholinergic regulation of female sexual behavior in rats demonstrated by manipulation of endogenous acetylcholine.

Infusions of the cholinesterase inhibitor, eserine, into the lateral ventricle of the brain facilitated lordosis in ovariectomized, estrogen primed female rats. Lordosis was also facilitated by infusions of 5 or 10 micrograms acetylcholine when this was accompanied by a low dose of eserine. Systemic treatment with the muscarinic antagonist, atropine (2 mg), completely blocked the facilitative effects of eserine and acetylcholine. In female rats made highly receptive by treatment with estrogen and progesterone, lordosis was inhibited by infusion of scopolamine into the lateral ventricles. These results agree with previous findings that sexual receptivity is regulated in part by endogenous cholinergic activity.

Acetylcholine↗
PubMed1987

Exchange lists: revised 1986.

A committee composed of members of The American Dietetic Association and the American Diabetes Association has revised Exchange List for Meal Planning. Changes were made, as deemed necessary, on the basis of nutritional recommendations for persons with diabetes as understood in 1986. Major changes include rewriting the text to make it more useful in the education of persons with diabetes; changing the order of the exchange lists to emphasize a high-carbohydrate, high-fiber diet, as well as to better reflect the order of foods in menu planning; adding symbols to foods high in fiber and sodium; changing nutritive values for the starch/bread and fruit lists; adding lists of combination foods, free foods, and foods recommended only for occasional use; developing a data base; and initiating a plan for field testing and evaluation. The committee also developed a simplified meal planning tool, Healthy Food Choices, to be used for initial or "survival" level education. In poster format, foods are grouped by calories into six food groups. Approximate portion sizes of commonly used foods are listed. Blank lines are provided for the nutrition counselor to write in a suggested menu or meal plan for the client. Because the booklet does not use the word "diabetes" specifically, it is appropriate as a general teaching tool.

Diabetes Mellitus↗
PubMed1986

Dynamic process captured on a single image: an approach to screening for abnormal superior vena caval flow.

A strategy for displaying and archiving dynamic quantitative data from scintigraphic imaging is described and applied to diagnosing obstructed thoracic veins. A prospective series of 25 patients with concurrent radiographic contrast and tracer venograms along with 49 controls showed a 33% sensitivity, comparable to previously published data. The use of first harmonic Fourier analysis enhanced the screening value of the test by identifying all abnormals. Moreover, this format captured the dynamic physiologic data on a single photograph. This technique is readily available to nearly any nuclear imaging laboratory equipped with a gamma camera and a computer.

Computers↗