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Biomedical subjects

M Contreras

Publications and source records attributed to M Contreras.

At least 91 records · Page 5Linked to original sources
PubMed1994

Is the unpaid/paid donation debate for better or for worse?--advantages of unpaid donations.

It is suggested that the best quality blood and blood products are obtained from voluntary unpaid donations as these are given for genuine altruistic reasons. Voluntary donors have no reason to give false information about lifestyle factors which might place them at risk of transmitting infectious agents. There is therefore a reduced risk of obtaining blood during the 'window' period of HIV infection. In addition if a component of a donation transmits an infectious agent, the fractionation plant can be informed to exclude the plasma from that donation or even recall the pertinent blood products. Several countries are already self-sufficient in blood and blood products, based on a voluntary, unpaid donor system.

AIDS Serodiagnosis↗
PubMed1994

Transplacental IgG subclass concentrations in pregnancies at risk of haemolytic disease of the newborn.

The relationship of haemolytic disease of the newborn (HDN) to the transplacental passage of the four IgG subclasses was assessed at various gestational ages by comparing the maternal and fetal IgG subclass concentrations in 34 pregnancies at risk of HDN with those in 30 pregnancies not at risk. Higher maternal and fetal IgG1 levels were attained in pregnancies at risk of HDN than in pregnancies not at risk. In contrast, a slight decrease in maternal IgG2 and IgG4 levels occurred in pregnancies at risk of HDN, as compared with a slight rise in maternal IgG2 and IgG4 levels in pregnancies not at risk of HDN. Changes in fetal IgG2 and 4 concentrations in either type of pregnancy were very similar, showing only slight increases between the 19th and 34th week of gestation. A slight decrease in maternal IgG3 occurred in both types of pregnancy. In contrast, higher and fairly steady levels of fetal IgG3 were observed in fetuses not at risk of HDN throughout gestation, when compared with those in 'at risk' pregnancies. However, the statistical reliability of these results is not clear since only small numbers of samples were tested and because wide variations in IgG concentrations were observed. The IgG subclass concentrations in 50 paired maternal and cord blood samples were also measured and revealed that IgG1 levels were substantially higher in cord rather than maternal blood; cord and maternal IgG2, 3 and 4 levels, on the other hand, were fairly similar.

Erythroblastosis, Fetal↗
PubMed1993

Prevalence of antibodies to human T cell leukaemia/lymphoma virus in blood donors in north London.

OBJECTIVES: To determine the prevalence of antibodies to the human T cell leukaemia/lymphoma viruses (HTLV-I and HTLV-II) in blood donors in north London in order to assess the economic impact and the logistic effects that routine screening would have on the blood supply. DESIGN: All donations collected by the north London blood transfusion centre between January 1991 and June 1991 were screened for antibodies to HTLV-I and HTLV-II by modified, improved Fujirebio gel particle agglutination test. Positive samples were titrated and retested as necessary. SUBJECTS: 96,720 unpaid volunteers, who gave 105,730 consecutive donations of blood and plasma. SETTING: North London blood transfusion centre. MAIN OUTCOME MEASURE: Observed numbers of donors confirmed to be seropositive for HTLV by reference laboratories. RESULTS: Of 2622 (2.5%) initially reactive samples, 414 (0.4% of all samples) gave a titre of > or = 1 in 16 on the modified agglutination test. Thirty five of the 414 serum samples yielded positive results on one of two enzyme linked immunosorbent assays (ELISA (Cambridge Biotech and Abbot)), and none of these results were confirmed by either reference laboratory. Five samples yielded positive results on both ELISAs and all five of these were confirmed to contain antibodies to HTLV. One of the five contained antibodies to HTLV-II and the others antibodies to HTLV-I. Four seropositive donors were white women whose only risk factor for infection was sexual contact. The fifth (positive for antibodies to HTLV-II) was an Anglo-Caribbean man who admitted to previous misuse of intravenous drugs. CONCLUSION: The prevalence of antibodies to HTLV in blood donors in north London was one in 19,344 (0.005%). Up to 100 donors a year might be identified in the United Kingdom as being infected with HTLV, although prevalence in different regions may vary considerably.

Adult↗
PubMed1993

Occult blood and fecal leukocytes as screening tests in childhood infectious diarrhea: an old problem revisited.

During a 24-month period 446 children with diarrhea and 16 controls had examination of their stools for leukocytes and for occult blood. Fecal leukocytes were found in 36, 16 and 18% of children with Salmonella-Shigella-Campylobacter, rotavirus or enterotoxigenic Escherichia coli, or cryptosporidial diarrhea, respectively. Similarly 43, 39 and 38% of these groups, respectively, as well as 13% of controls had occult blood. Notably 70% of 10 Shigella cases had fecal leukocytes. In 166 children with mixed pathogens leukocytes were seen in 27 and 8% of children with Salmonella-Shigella-Campylobacter or noninvasive pathogen, respectively. Likewise 44 and 18% of these groups had occult blood. Agreement between both tests being positive was poor, the highest result being 50% for Shigella. Dysentery combined with both tests positive was associated with 15 (88%) cases of invasive agents present in stool cultures, and combination of dysentery with fecal leukocytes was associated with 21 (72%) cases of invasive agents recovered. The results of these tests should be interpreted in the context of the clinical situation. A combined clinical-epidemiologic and screening tests-based approach to infectious diarrhea of childhood is suggested.

Campylobacter Infections↗
PubMed1993

[Pseudopodagra caused by hydroxyapatite. Report of 3 cases].

Calcium hydroxyapatite crystals deposit in periarticular soft tissues usually translates itself clinically through pain and mobility limitation of affected joint. Compromise of small joints in feet is infrequent, less than 1% of all cases. Recently pseudopodagra crises have been described due to the deposit of this material in soft tissues adjacent to metatarsal or phalangeal first joint. Its clinical expression is practically undistinguishable from gout crises. Three new cases of pseudopodagra due to hidroxyamatite are presented and some considerations are made concerning this clinical entity and its differential diagnosis in relation to gout.

Adolescent↗
PubMed1992

[Serologic diagnosis of Lyme disease in patients with undifferentiated arthritis. Diagnostic problems].

BACKGROUND: Arthritis is a frequent manifestation of Lyme disease. The diagnosis of this disease is especially supported by serological techniques which however have false positives or negatives. The aim of this study was to establish the frequency of serologies positive to Borrelia burgdorferi in patients with non-filiated arthritis and in other well defined rheumatic diseases. METHODS: A prospective study was performed to detect antibodies (AB) versus Borrelia burgdorferi in 43 patients with undifferentiated arthritis and in 100 patients with articular disease of precise diagnosis (rheumatoid arthritis, systemic lupus erythematosus, psoriasis arthropathy, and reactive arthritis/Reiter's syndrome). The technique was performed by indirect immunofluorescence and was repeated by enzymoimmunoassay in doubtful or positive results. Titers greater than 1/256 were considered as positive. RESULTS: Positive serology was found in two patients with undifferentiated arthritis and in one patient with Reiter's syndrome. None of the three patients referred the antecedent of erythema chronicum migrans. Positive serology was not observed in any of the patients with rheumatoid arthritis, systemic lupus erythematosus or psoriatic arthritis. CONCLUSIONS: A small proportion of patients with undifferentiated arthritis or Reiter's syndrome presented positive serology at low titers versus Borrelia burgdorferi with the interpretation of these results being difficult. The frequency of seropositivity in rheumatoid arthritis and systemic lupus erythematosus is very low.

Adult↗