Biomedical subjects

L V Kirchhoff

Publications and source records attributed to L V Kirchhoff.

59 records · Page 4Linked to original sources

PubMed1980

A case-control study of Hodgkin's disease in Brazil. I. Epidemiogic aspects.

A number of epidemiologic variables were investigated in a case-control interview study, conducted in São Paulo, Brazil, of 70 Hodgkin's disease (HD) patients, 70 tumor control subjects matched for age and sex, and 128 siblings of the patients. The major epidemiologic findings were a high percentage of total cases among children, with a high sex ratio, a relative predominance of the mixed cellularity histologic subtype, and a bimodal age-specific incidence curve with the highest rates among young adults and the elderly. When the matched controls were used as the comparison group, high socioeconomic status (SES) was found to be associated with an increased risk for HD (p = 0.001). On the basis of the case-sibling comparison, an association between prior tonsillectomy and risk for HD was found (p = 0.04), and the relative risk for HD among tonsillectomized persons as compared to individuals who had not had the operation was 2.5. Other variables, including sibship size, birth order, marital status, occupational exposure, prior use of amphetamines or diphenylhydantoin, intensity of exposure to children and history of viral illnesses were not found to be determinants of risk for HD in this study.

Adolescent↗

PubMed1980

A case-control study of Hodgkin's disease in Brazil II. Seroepidemiologic studies in cases and family members.

A case-control study of antibody titers to the viral capsid antigen of Epstein-Barr virus was carried out in 70 patients with Hodgkin's disease (HD) and in 92 siblings, 50 parents and 19 children of the HD patients, each paired with a control matched for age and sex. The geometric mean titer (GMT) of the HD patients was significantly greater than that of the controls (t69 = 6.30, p < 0.0005), and the proportion of HD cases with titers greater than or equal to 1:320 was significantly elevated (35.5% vs. 2.9%). No significant differences in GMTs were found when the HD patients were grouped by sex or by histologic subtype. An inverse correlation between age and titer was noted among HD patients but not among controls. The GMT of the 161 relatives of the HD cases was similar to that of their respective controls. Likewise, there was no significant elevation of the GMT of the subset consisting of family members of HD patients with high titers when compared to controls. However, when the GMT of the family members of HD patients with high titers was compared to that of the relatives of the HD patients with low titers, a significant difference was found (t159 = 2.54, p < 0.01).

Adolescent↗

PubMedDate not supplied

Maxicircle genomic organization and editing of an ATPase subunit 6 RNA in Trypanosoma cruzi.

The DNA sequence of a 5736-nucleotide (nt) Trypanosoma cruzi maxicircle fragment was determined. Sequence comparisons indicate that its 5' terminus is the homologue of the downstream portion of the NADH dehydrogenase subunit 7 gene and that its 3' region is homologous to the maxicircle unidentified reading frame II gene. The region between these two gene segments contains six additional genes that encode mitochondrial proteins, including ATPase subunit 6 (A6). Comparison of the A6 maxicircle DNA sequence with that of an A6 cDNA indicates that the A6 RNA is extensively edited throughout its length. A 49-nt sequence that could serve as template for transcription of a guide RNA for editing a segment of the A6 RNA was found in one of 24 minicircle variable regions sequenced. Moreover, the presence of an RNA having this sequence was demonstrated in an RNAse protection assay. This is the first identification of a guide RNA template in a T. cruzi minicircle. Taken together, our findings suggest that T. cruzi and Trypanosoma brucei brucei are phylogenetically closer to each other than they are to Leishmania tarentolae, despite the relative similarity of the life cycles of the latter and T. cruzi.

Adenosine Triphosphatases↗

PubMedDate not supplied

Use of the polymerase chain reaction for detecting Trypanosoma cruzi in triatomine vectors.

Determination of the rate of Trypanosoma cruzi infection in its triatomine vectors is an element in control programmes directed at reducing transmission of the organism to humans. Traditionally, T. cruzi has been detected in these insects by microscopical examination of intestinal contents or excreta. The sensitivity of this laborious process has not been defined because of the lack of a bench-mark method against which microscopical examination could be compared. The purpose of this study was to compare the sensitivity of a polymerase chain reaction (PCR) assay with that of microscopical examination for detecting T. cruzi in Triatoma infestans nymphs that had fed on patients with chronic Chagas disease. To this end, we analysed 54 pairs of samples, each containing 2 groups of 10 insects, obtained by feedings on 19 patients with chronic T. cruzi infection, 17 of whom were fed upon 3 times. One group of insects in each pair was analysed by PCR and the other by microscopical examination of excreta. Overall, the PCR assay gave positive results in 32 of 54 groups of insects examined (59%), whereas only 7 of 54 groups (13%) were positive by microscopical examination (P = 0.038). These results demonstrate that the PCR assay is significantly more sensitive for the detection of T. cruzi in triatomine vectors than is microscopical examination, and suggest that the PCR assay could be a useful tool in epizootiological studies.

Animals↗

PubMedDate not supplied

Prevalence of antibody to Trypanosoma cruzi among blood donors in Los Angeles, California.

Transfusion-associated Chagas' disease is a serious public health problem in Central and South America. With the recent influx of immigrants from Chagas' disease-endemic areas, concern about the risk of disease from blood transfusion has increased in the United States. To assess the prevalence of Trypanosoma cruzi infection in one area, 1024 consecutive blood donations from 988 voluntary blood donors at a medical center in Los Angeles County were screened serologically. The median age of donors screened was 32.5 years; 53.4 percent were male, and 38.4 percent were born in Chagas' disease-endemic countries. All donor sera were tested by complement fixation (CF) and indirect immunofluorescence (IIF) tests. A radioimmunoprecipitation assay (RIPA) was also done on all sera from CF- or IIF-reactive donors and an equal number of sera from nonreactive donors. A second serum specimen was obtained, and interviews were completed for 18 (67%) of 27 donors with an initial CF titer greater than or equal to 8 or an IIF titer greater than or equal to 64. The overall seroreactivity (by CF and IIF) was 1.1 percent (11/988). One donor (0.1%) had antibody specific to the 72- and 90-kDa antigens of T. cruzi on RIPA. Seven recipients of blood components from the seroreactive donors were located and were seronegative at 3 to 6 months. Seroreactive donors were 3.6 times more likely to have been born or to have resided in Mexico or Central America, 8.7 times more likely to have donated blood in the past, and 11.8 times more likely to have a history of malaria prophylaxis or treatment.

Adolescent↗