Biomedical subjects

K Siller

Publications and source records attributed to K Siller.

9 recordsLinked to original sources

PubMed2000

Early phase karyotype analysis of chromosome segregation after formation of mouse-mouse hybridomas with chromosome painting probes.

FISH analysis with chromosome painting probes allows, better than karyotyping after Giemsa banding, the study of chromosome segregation after hybridoma formation. FISH is particularly useful for intraspecies hybrids and allows visualization of small chromosome fragments. Cell hybrids were constructed between P3 x 63Ag8.653 mouse myeloma cells and lymphocytes from BALB/c mice by PEG fusion and by selection in hypoxanthine azaserine medium. Three hybridomas (A4, D8, F10) were selected and, after cloning, the cells were cultivated in vitro over a period of 28 days. During this time in culture, air-dried metaphase spreads were prepared by standard methods. For FISH chromosome painting, digoxigenin- and biotin-labeled mouse chromosome painting probes and rhodamine-antidigoxigenin antibodies and fluorescein-avidin were used for dual color detection. Total chromosome numbers and the numbers of mouse chromosomes 1, X, 6 and 12 were estimated as function of days in culture. Mean chromosome numbers of 78 (D8), 82 (F10) and 150 (A4) were observed. The major rearrangements of chromosome numbers occured in the first 28 days in culture and did not change significantly between day 28 and day 56. Mouse chromosome #12, which had the largest chromosome fragments in the parent myeloma, remained stable while the number of X chromosomes, which were significantly fragmented already in the parent myeloma, decreased by approximately 50%.

Animals↗

PubMed2000

A test for the determination of sustained attention in patients with obstructive sleep apnea syndrome.

BACKGROUND AND OBJECTIVES: To investigate the parameter daytime sleepiness in patients with the sleep apnea syndrome (SAS), a test for measurement of sustained attention was developed. The present studies were performed on volunteers undergoing preemployment medical examinations and SAS patients to determine the extent to which test results are in agreement with the symptoms of SAS and traffic accident reports, and also with daytime sleepiness, and whether learning or therapeutic effects can be seen with repeated tests prior to and following treatment with nasal continuous positive airway pressure (nCPAP). METHODS PARTICIPANTS: 125 healthy volunteers, and two groups of 28 SAS patients each. DESIGN: Study A: The volunteers underwent a single attention test and completed a questionnaire concerned with traffic accidents and symptoms of sleep-related breathing disorders. Study B: SAS patients underwent two attention tests before treatment. Study C: SAS patients underwent one attention test before and one after nCPAP therapy. RESULTS: Study A: The error rate in volunteers without symptoms of sleep-related breathing disorders (51 persons) was 4.7 +/- 4.3% (number of errors 14.1 +/- 12.9), 95% CI: 1.2 (number of errors 3.6). No dependence of the error rate on age, BMI or sex was found. In persons with a history of apneic events (n = 10), the error rate was 10.6 +/- 10.0% (number of errors 31.8 +/- 30), in those with more than two accidents during the last 5 years (n = 4), it was increased to 15.3 +/- 9.7% (number of errors 45.9 +/- 29.1). Study B: Among SAS patients, no significant learning effect was seen, and prolongation of the test duration beyond 30 min had no effect on the test results. Study C: The error rate improved significantly with nCPAP [10.6 +/- 13.5 vs. 6.4 +/- 8.9% (number of errors 31.8 +/- 40. 5 vs. 19.2 +/- 26.7), p < 0.001]. CONCLUSIONS: The attention test can be helpful for the measurement of daytime sleepiness, and CPAP therapy can improve test performance.

Accidents, Traffic↗

PubMed1993

Serologic validation of HIV infection in a tropical area.

We have defined human immunodeficiency virus type 1 (HIV-1) serologic reactivity in Brazilians living in an area endemic for tropical diseases. Enzyme-linked immunosorbent assay (ELISA) and Western blot (WB) analyses were performed on 342 patients with diseases including Chagas' disease, schistosomiasis, typhoid fever, helminthiasis, and cutaneous and visceral leishmaniasis. Nine percent of the visceral leishmaniasis patients' sera reacted in the HIV-1 ELISA but all were WB negative. All other sera from these patients were HIV negative. A total of 224 HIV-1 ELISA repeatedly positive sera also were HIV-1 WB tested. They were drawn from a total population of 19,230 individuals, including AIDS patients, blood donors, homosexual men, intravenous drug users, pregnant women, individuals with hemophiliac, and tuberculosis and sexually transmitted disease patients. The WB results were analyzed using five different interpretive criteria for WB positivity. The Centers for Disease Control (CDC) and the World Health Organization (WHO) criteria were the most sensitive and specific for identifying HIV-1-infected individuals. The WB pattern was similar to that seen in the United States. Envelope (ENV) protein antibodies were highly predictive of HIV-1 infection; none of the AIDS patients lacked ENV protein reactivity. We conclude that among the tropical diseases studied, only visceral leishmaniasis is associated with false-positive HIV-1 ELISA tests. Current CDC and WHO criteria for interpretation of HIV-1 WB tests are appropriate for Brazil.

Acquired Immunodeficiency Syndrome↗

PubMed1992

A developmentally regulated plasmalemmal antigen present in synaptosomes but not in growth cones.

Monoclonal antibody 2L4 was generated against rat synaptosomes but does not cross-react with nerve growth cones. Expression of the 2L4 antigen is developmentally regulated in a manner that is, in part, the opposite of the expression of the 5B4-CAM antigen, a marker of neuronal outgrowth belonging to the N-CAM family. While 5B4-CAM appears and increases during sprouting and then decreases to reach low levels in the adult, the 2L4 antigen appears only late in development, when neuronal outgrowth ceases, at or around the time of synaptogenesis. Once expressed, the antigen is found on the entire plasmalemmal surface of the neuron, but seems to be enriched at synaptic endings, at least of some neuron types. Biochemical analyses involving blotting of non-denaturing gels and immunoaffinity chromatography identify the antigen as a pair of polypeptides with similar, basic isoelectric points. These polypeptides form a somewhat diffuse, probably glycosylated band at 67 kDa and may be part of a hetero-oligomeric complex. The localization, biochemical, and developmental results suggest that the 2L4 antigen is a plasmalemmal marker of maturing and/or mature neurons whose expression may be triggered by synaptogenesis.

Aging↗

PubMed1974