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Biomedical subjects

R Dodd

Publications and source records attributed to R Dodd.

36 records · Page 2Linked to original sources
PubMed1994

Duration of time from onset of human immunodeficiency virus type 1 infectiousness to development of detectable antibody. The HIV Seroconversion Study Group.

BACKGROUND: For persons newly infected with the human immunodeficiency virus type 1 (HIV-1), the time from the onset of infectivity to the development of detectable HIV-1 antibody is unknown. Persons who donate blood during this period account for nearly all instances of HIV-1 transmission from HIV-1 antibody-screened blood transfusions. STUDY DESIGN AND METHODS: To estimate the window period from infectivity to HIV-1 antibody positivity, 701 HIV-1-seropositive blood donors who made a previous seronegative donation at 40 United States blood centers were studied. The HIV-1 antibody status was determined for at least one recipient of blood from the seronegative donation preceding the seropositive donation made by 182 of the 701 donors. RESULTS: There were 39 seropositive recipients of blood from these 182 donors. Three donors were excluded from further analysis because the seropositive recipients of their blood had other HIV-1 risk factors or had HIV-1 infection before transfusion. The final study population comprised the remaining 179 donors, of whom 36 (20%) transmitted HIV-1 infection to recipients. When the interval between the seropositive donation and the preceding seronegative donation was less than 180 days, 46 percent of the donors transmitted HIV-1. In contrast, when that interval exceeded 540 days, only 2 percent transmitted HIV-1. A mathematical model was developed to explain the relationship between the probability that the previous seronegative donation occurred during the donor's window period of infectiousness, and hence transmitted HIV-1, as a function of both the window period and the duration between the seropositive and previous seronegative donations. This model indicated that the transmission data were most consistent with an average window period of 45 days. Assuming a log-normal window period distribution, it was estimated with 95 percent certainty that at least 90 percent of persons had a window period of less than 141 days. CONCLUSION: The window period averages 45 days, with few, if any, donors remaining infectious and seronegative for longer than 6 months.

Adolescent↗
PubMed1993

Factors affecting Yersinia enterocolitica (serotype O:8) viability in deliberately inoculated blood.

Interpretation of in vitro experiments using Yersinia enterocolitica in blood components requires information on factors affecting the organism's survival. Several factors were found to influence the survival of Y. enterocolitica (serotype O:8) in blood components. A 20-minute room-temperature incubation with plasma-containing components resulted in approximately 2 log10 inactivation. Inactivation could be prevented by preincubation treatment of the plasma at 55 degrees C for 1 hour, which suggests the involvement of heat-labile plasma factors. No antibacterial activity was observed in washed red cells during the 20-minute room-temperature incubation. However, Y. enterocolitica colony-forming units declined by up to 2 log10 in washed red cells during the first days of 4 degrees C storage. Use of a white cell-reduction filter on freshly inoculated samples removed approximately 1 log10 of the organism regardless of whether bacteria were suspended in saline or washed red cells. Thus, bacterial levels may be affected by plasma, cellular components, and white cell-reduction filters. However, caution should be exercised in interpreting in vitro spiking studies designed to investigate the potential benefits of white cell reduction to eliminate the growth of Y. enterocolitica because of potential differences between naturally infected and experimentally inoculated blood.

Bacterial Adhesion↗
PubMed1988

Chorionic gonadotrophin-beta mRNA, a trophoblast marker, is expressed in human 8-cell embryos derived from tripronucleate zygotes.

Human chorionic gonadotrophin beta (HCG-beta) is a trophoblast marker. Its expression is normally limited to syncytiotrophoblast cells of chorionic villi, although it is known to be secreted from the human embryo as early as 7 days post-fertilization. To examine the onset of embryonic transcriptional activity of the gene encoding this polypeptide we have performed in-situ hybridization to cellular RNAs of human tripronucleate preimplantation embryos. We see expression of HCG-beta RNA at the 6-8-cell stage, before morphological differentiation between trophectoderm and inner cell mass is apparent. We believe that this RNA is the product of de novo transcription from the embryonic genome, since transcripts are only observed in embryos of at least 2 days post-fertilization in age.

Blastocyst↗
PubMed1985

Visualization by positron emission tomography of the apparent regional heterogeneity of central type benzodiazepine receptors in the brain of living baboons.

The feasibility of visualizing the heterogeneity of benzodiazepine (BDZ) receptors in the brain of living baboons was investigated using Positron Emission Tomography. Ethyl 8-fluoro-5,6-dihydro-5-methyl 6-oxo-4H-imidazo (1,5-a) (1, 4) benzodiazepine-3-carboxylate (RO 15 1788) labelled by carbon 11 (11C-RO 15 1788) was I.V. injected for the "in vivo" labelling of the central type BDZ receptors. Displacement experiments were performed 20 minutes after the administration of the radioligand by two different cold drugs: RO 15 1788 which has an equal affinity for central type BDZ receptors, and propyl B-Carboline-3-carboxylate (B-CCP) which favours the sites located in the cerebellum. Different sensitivities to these two drugs displacement of 11C-RO 15 1788 binding "in vivo" were observed: on the one hand in the regional localization of the displacement, and on the other hand, in the amount of the radioactivity displaced. The apparent interregional heterogeneity of the displacement seen in the cerebellum and in the temporal cortex are discussed in terms of discrepancies observed "in vitro" at physiological temperature, between cerebellar and non-cerebellar BDZ central type binding sites.

Animals↗
PubMed1984

[Potent convulsant effects of a benzodiazepine inverse agonist, methyl beta-carboline-3-carboxylate in cats].

The convulsant properties of methyl beta-carboline-3-carboxylate (beta-CCM), which is a homologue of a putative benzodiazepine receptor ligand in the mammalian central nervous system, were examined in cats. Subcutaneous injection of 0.5 mg/kg of the beta-CCM produced various degrees of myoclonic jerks always accompanied by cortical spike burst. Some autonomic symptoms such as tachypnea, hypersecretion of thick mucous saliva, vomiting and mydriasis were also presented. Subcutaneous injection of 1.0 mg/kg of the compound induced a generalized tonic-clonic convulsion. Injection of the same amount of the drug 1 hour later in the same cats failed to provoke a generalized seizure. Repeated injection of the same dose 3 hours later provoked a generalized seizure, but with a longer latency. However, repetition of the experiments 24 hours after or 10 days after the first injection consistently induced the same type of generalized seizure with the same latency as the first injections. These results support the suggestion that the pharmacological effect, especially the convulsive effect, of beta-CCM is dose-related, reversible and reproducible in the same cats and among different cats. Moreover, the postictal refractory period in this model of epilepsy may continue about for 3 hours.

Animals↗
PubMedDate not supplied

Health, development and the Millennium Development Goals.

The Millennium Development Goals (MDG), which emerged from the United Nations Millennium Summit in 2000, are increasingly recognized as the over-arching development framework. As such, the MDG are increasingly guiding the policies of poor countries and aid agencies alike. This article reviews the challenges and opportunities for health presented by the MDG. The opportunities include that three of the eight MDG relate to health--a recognition that health is central to global agenda of reducing poverty, as well as an important measure of human well-being in its own right. A related point is that the MDG help to focus attention on those health conditions that disproportionally affect the poor (communicable disease, child health and maternal health), which should, in turn, help to strengthen the equity focus of health policies in low-income countries. Further, because the MDG are concrete, it is possible to calculate the cost of achieving them, which in turn strengthens the long-standing calls for higher levels of aid for health. The challenges include that, while the MDG focus on specific diseases and conditions, they cannot be achieved without strengthening health systems. Similarly, progress towards the MDG will require health to be prioritized within overall development and economic policies. In practice, this means applying a health 'lens' to processes such as civil-service reform, decentralization and the drawing-up of frameworks of national expenditure. Finally, the MDG cannot be met with the resources available in low-income countries. While the MDG framework has created pressure for donors to commit to higher levels of aid, the challenge remains to turn these commitments into action. Data are presented to show that, at current rates of progress, the health-related MDG will not be achieved. This disappointing trend could be reversed, however, if the various challenges outlined are met.

Developing Countries↗
PubMedDate not supplied

Methodologic approaches to surveillance of HIV infection among blood donors.

Blood donors make up the largest group in the United States that is tested for human immunodeficiency virus, type 1 (HIV) antibody. The blood donor population is ideal for detecting and quantifying uncommon or unrecognized modes of HIV transmission in the general population because persons at known risk for HIV infection are excluded from donating blood. The national HIV surveillance program consists of a centralized computer database of information on all donations at selected American Red Cross blood centers, which together account for about a quarter of the blood supply, and all donations at 20 regional blood centers where seropositive blood donors are interviewed to evaluate their risk factors for HIV infection and to determine their epidemiologic characteristics and motives for donation. Trends in HIV prevalence and incidence within specific demographic subgroups are determined for first-time and repeat donors. Combining the trends with HIV-risk profile data from seropositive donors provides a rate for HIV seropositive donors with no identified risk. Epidemiologic and behavioral data from seropositive donors will help in the development and evaluation of future donor deferral strategies.

Blood Banks↗