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Biomedical subjects

R D Wegner

Publications and source records attributed to R D Wegner.

At least 55 records · Page 3Linked to original sources
PubMed1987

Monoclonal antibody with specificity to mitotic chromosomes of primates.

Fusion of a cell in mitosis with a cell in interphase results in the condensation of chromatin in the interphase nucleus into chromosomes. Premature chromosome condensation is caused by certain proteins, called mitotic factors, that are present in the mitotic cell and are localized on chromosomes. Extracts from mitotic cells were used to immunize mice to produce monoclonal antibodies specific for cells in mitosis. Among the antibodies obtained, the MPM-4 antibody defines a 125-kD polypeptide antigen located on mitotic chromosomes by indirect immunofluorescence. Although the polypeptide antigen is present in approximately equal concentrations in extracts of interphase cells and mitotic cells, as revealed by immunoblots, it cannot be detected cytologically in the former. Cell fractionation experiments showed that the 125-kD antigen is found in the cytoplasm of interphase cells and metaphase cells, but is concentrated in fractions containing metaphase chromosomes, although not detectable in interphase nuclei. Even though the antigen is apparently primate-specific, it binds to mitotic chromosomes and prematurely condensed chromosomes in human-rodent cell hybrids without regard to the species of origin of the mitotic inducer. The presence of the antigen in the cytoplasm of interphase cells and the chromosomes of mitotic cells suggests a relationship between the presence of the antigen on chromosomes and the process of chromosome condensation and decondensation.

Animals↗
PubMed1986

Dermatoglyphic peculiarities in families with X-linked mental retardation and fragile site Xq27: a collaborative study.

The dermatoglyphic patterns of fingertips, palms and soles of 75 male patients with X-linked mental retardation and fra-Xq27 and of 28 obligate female heterozygotes were analyzed and compared with the data from 200 male and 200 female control individuals. The results show that there is a strong association between the fra-X-syndrome and dermatoglyphic peculiarities observed in male patients and also in female heterozygotes. The characteristic dermatoglyphic features of the fra-X-syndrome are: increased frequencies of radial loops, whorls and arches on the fingertips, a pronounced transversal course of palmar ridges, lower a-b RC, absence of c-triradii on the palms, abnormal palmar and plantar creases, dysplasia of the papillary ridges and low frequencies of true patterns on the soles. Some of these patterns were found in the female carriers of fra-Xq27 also. The combination of palmar and plantar patterns, expressed by a "log. score-Index", provides a high degree of discrimination between the male patients with fra-X-syndrome and the control group. A preliminary log. score-Index was developed also for the female heterozygotes. A "phantom picture" of the dermatoglyphic stigmata is constructed. We suggest that dermatoglyphic examination of the members of families suspected for fra-Xq27-syndrome can be useful for predicting this state and for diagnosing male hemizygotes and carrier females.

Adolescent↗
PubMed1986

Cri du chat-syndrome in combination with partial trisomy 9 p.

A partial monosomy 5p leading to the Cri du chat-Syndrome combined with a partial trisomy 9p was observed in a mentally defective boy with typical clinical features for both syndromes. This chromosomal aberration is inherited from a t [5; 9] (p. 13.3; 13.1) translocation carrier father. Further family investigations showed many balanced translocation carriers through several generations.

Abnormalities, Multiple↗
PubMed1983

A new inducible fragile site on chromosome 3(p14.2) in human lymphocytes.

A fragile site on chromosome 3(p14.2) was found in lymphocytes of two unrelated patients. Expression of the trait with 6%-18% affected cells could only be demonstrated under culture conditions favouring a low concentration of folic acid. Family investigations proved the maternal transmission of the cytologic marker in one case. In contrast to other fragile sites chromatid type aberrations predominated.

Abnormalities, Multiple↗
PubMed1983

Caffeine-mediated release of alpha-radiation-induced G2 arrest increases the yield of chromosome aberrations.

Severe and partly irreversible G2 arrest caused by americium-241 alpha-particles in Chinese hamster V79 cells acted as a competing process to the yield of detectable aberrant mitoses at metaphase. With increasing dose of alpha-radiation an increasing fraction of cells was irreversibly arrested in G2 with the consequence of interphase death before the first post-irradiation mitosis. This irreversible G2 arrest (demonstrated by flow cytofluorometry and mitotic indices) could be overcome by adding caffeine 8 hours after irradiation, the time point of maximum G2 arrest (80-90 per cent of all cells). Within 3.5 hours the number of aberrant mitoses increased by this treatment from 54 to 96 per cent and from 65 to 99.9 per cent for doses of 1.75 and 4.38 Gy of alpha-particles, respectively. The aberration frequency per mitotic cell, scored as chromatid and isochromatid breaks, rings, interchanges and dicentrics increased by a factor of about 3 after releasing G2 arrested cells. The frequency distribution of aberrations per cell revealed that, after 4.38 Gy, 58 per cent of the formerly G2-arrested cells had more than five aberrations per cell compared to only 8 per cent without the interaction of caffeine.

Alpha Particles↗
PubMed1983

Investigation into the possible genetic effects of diagnostic ultrasound.

The mutagenic effect of DUS (diagnostic ultrasound) was examined using two generators emitting continuous waves and pulsed waves, respectively. Three different test systems for mutagenic activity were employed in this study. 1. The frequency of sister chromatid exchanges (SCEs) was determined in metaphase chromosomes of human lymphocytes and of Chinese hamster ovary (CHO) cells sonicated at different stages of the cell cycle. 2. The induction of DNA single strand breaks was tested in CHO cells treated with continuous wave ultrasound. Following sonication an endonuclease was introduced into the cells converting single strand breaks to chromosomal aberrations scorable in the following metaphase. 3. The influence of DUS on the number of point mutations was evaluated in the Ames test. A tester strain of Salmonella typhimurium indicating base substitutions was sonicated. At the present stage, all results proved to be completely negative and could thus not support the view of any mutagenic activity of diagnostic ultrasound.

Animals↗
PubMed1982

12-O-tetradecanoylphorbol 13-acetate-inducible proteins are synthesized at an increased rate in Bloom syndrome fibroblasts.

A set of proteins, which in normal fibroblasts were barely, if at all, detectable, were synthesized at an increased rate in fibroblasts from patients with Bloom syndrome (BS). The same set of proteins was induced in normal human fibroblasts by treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA). In BS cells, TPA caused a further 2-fold increase in the rate of synthesis. Production of these proteins was inhibited by the addition of fluocinolone acetonide to the culture medium. One of the proteins (XHF1) present at high levels in BS fibroblasts and in TPA-treated cells was also induced by irradiation with ultraviolet light. This protein was secreted into the culture medium. Most other TPA-inducible proteins were cytoplasmic. Among other human mutants prone to chromosome aberrations we found one of three tested cases of Fanconi anemia and one case of ataxia-telangiectasia that showed increased spontaneous rates of synthesis of the TPA-inducible proteins. In these cases, however, the induction by TPA was like that seen in healthy fibroblasts.

Bloom Syndrome↗
PubMed1980

Has diagnostic ultrasound mutagenic effects?

Chinese hamster ovary cells were treated with ultrasound from a fetal pulse detector (Eucotone, Siemens) operated at 10 mW/cm2 and 2.2 MHz. The frequencies of structural chromosomal aberrations and of sister chromatid exchanges were not increased by the treatment. There was no indication of single-strand breaks induced by ultrasound in the G2 phase of the cell cycle.

Animals↗
PubMed1980

Different sensitivity of diploid and trisomic cells from patients with Down syndrome mosaic after treatment with the trifunctional alkylating agent trenimon.

Normal and trisomic cells of patients with Down syndrome mosaic offer the unique possibility to study the effect of an additional chromosome no. 21 against an identical genetic background. Here we show that a significant increase in the frequency of Trenimon induced sister chromatid exchanges (SCEs) and chromosome aberrations can be found in trisomic lymphocytes and fibroblasts as compared to disomic cells. The relative increase was clearly higher for chromosomal breaks than for SCEs.

Alkylating Agents↗
PubMed1980

Activity of rRNA genes in cells of a patient with Down syndrome mosaic.

Disomic and trisomic cells of a patient with Down syndrome mosaic were used to study the effect of the additional chromosome 21 against an identical genetic background. The frequency of AG staining and the participation in satellite associations were determined for each pair of acrocentric chromosomes. The additional chromosome 21 of the trisomic cells and its homologues proved to be regularly Ag positive. Therefore the trisomic cells showed more AG positive chromosomes and more satellite associations per cell than the diploid cells. Thus, no compensation for the additional rRNA-gene dose could be found in the cells of the trisomic line.

Cells, Cultured↗