Biomedical subjects
Publications and source records attributed to U Friedrich.
By aid of fluorescent centromere markers in chromosome No. 3 it could be shown that crossing over in a translocation quadrivalent had occurred on two occasions in a father who is carrier of a 3/5 translocation. This case demonstrates that marker chromosomes cannot always be used to trace the parental origin of structurally abnormal chromosomes.
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The lengths of the secondary constrictions of chromosomes 1, 9, and 16 vary with the degree of contraction of the chromosomes but these constrictions contract to a lesser degree than the euchromatic portions of the chromosomes. The regression coefficient for the regression of the length of the secondary constriction on the length of the euchromatic part of the chromosomes is shown to be larger for large constrictions. It is furthermore shown that there is a linear correlation between the regression coefficient and the size of the secondary constriction in question. This linear correlation makes it possible to correct the lengths of the secondary constrictions to the lengths expected when contraction is average. The correction method is used in a sample of 30 couples, and on the basis of this sample, the normal limits for the lengths of the secondary constrictions in chromosomes 1, 9, and 16 are defined.
We have analyzed forward-mutation specificity in S49 mouse T lymphoma cells. Our criteria of specificity were based upon relative mutabilities of a panel of 3 genetic markers: resistance to 6-thioguanine (6TGr), dibutyryl cAMP (bt2cAMPr), and ouabain (OUAr). We tested 2 monofunctional alkylating agents, ethyl methane-sulfonate (EMS) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), and 2 heterocyclic compounds, ICR-191 and aflatoxin B1 (AFb1). AFB1 was activated with rat-liver microsomal S9 plus cofactors. Expression-time lags of each genetic marker ranged from 2 days of OUAr mutations to 6 and 8 days for bt2cAMPr and 6TGr cells, with stable induced mutant fractions thereafter. The relative activity of each agent for each marker was assessed on the basis of its mutagenic efficiency at equitoxic doses. Specificity differences between the agents were determined by taking ratios of mutagenic efficiencies (RME) for the 3 possible pairs of markers. From these quantitative correlations and other data we conclude that both MNNG and EMS induce ouabain resistance (and probably bt2cAMPr and 6TGr) by similar mechanisms, almost certainly base substitutions. In contrast, ICR-191 and AFB1 are respectively less than 2 and 3% as efficient as MNNG for OUAr mutant induction relative to the activity of each agent for 6TGr mutagenesis. We infer that ICR-191 and AFB1 very rarely cause base substitutions in S49 cells, but that their activities are consistent with production of deletions, insertions or chromosomal aberrations. S49 cells demonstrate an unusually high specificity of mutagenesis at the OUAr locus compared to several other rodent cell lines. Thus, this panel of markers in S49 cells can be used as a sensitive, reliable screening system for mutagen detection and to discriminate among major classes of mutagenic mechanisms.
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Two patients with an inverted duplication of bands 8p21-p23 are described. The gene for glutathione reductase (GSR; E.C.1.6.4.2) has previously been localized to band 8p21. In one of the patients subband 8p21.1 was included in the duplication; GSR activity in the red blood cells was increased. In the other patient, subband 8p21.1 was not included in the duplication and GSR activity was normal. This allows GSR to be assigned to subband 8p21.1. Including the present 2 patients, at least 13 cases of this abnormality have been published. We have obtained data on at least 8 further cases (unpublished). We conclude that inv dup (8p) is a non-randomly occurring de novo structural aberration in man. The GSR results in our cases prove that breakpoints can be different in different patients. Clinical symptoms and signs include some common features but show marked interpatient variation which should, at least in part, be caused by the differences in break-points. A detailed collaborative study to determine the clinical and epidemiological features of this entity is recommended.
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A case of malignant choroid plexus papilloma of the brain with severe hypodiploidy is presented. The hypodiploidy was estimated by means of flow cytometric measurements of the nuclear DNA content in two investigations with an interval of 21 months. The latter investigation was supplemented with chromosome analyses including quinacrine bonding. A modal chromosome number of 34 to 35 was found with a consistent loss of one chromosome Nos. 2, 3, 4, 5, 10, 13, 14, 15, 17, and 18, and no major structural changes. The corresponding calculated DNA content per nucleus correlated very well with the measured content, which was found to be 75% of the male diploid amount. The paper briefly discusses cell survival in extreme hypodiploidy and provides a comparison with cases from the literature in which banding analysis gives comparable information.
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Twenty patients managed with Adaptic, Concise-capsule, Epoxydent, and a dispersion alloy (all class II cavities) were re-examined after three years. Between 20% to 45% of the composite fillings had been replaced in this time period, but only 5% of the amalgam fillings had been renewed. Marginal defects were diagnosed with the probe in 53% to 89% of the composite fillings (amalgam, 21%); marginal discoloration was observed in 61% to 100% of the cases. With the exception of Adaptic (discolorations found in "only" 44% of the cases), all other composite fillings were discolored (100%). The following reduction in tooth structure was noted after a three year period: amalgam, 0 micron +/- 112 micron; Expoxydent, 56 micron +/- 138 micron; Adaptic, 224 micron +/- 151 micron; Concise, 201 micron +/- 93 micron.
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Thoracic teratomas are rare in children. They present a heterogeneous and problematic group of tumours. Extramediastinal lesions are unusual. Tomography is of particular value in cases of mediastinal teratomata, as this allows differentiation between the tumour and the heart. Of 31 cases of intrapulmonary teratoma that have been described, only 3 were in children. The authors report a unique case of combined mediastinal and intrapulmonary teratoma.
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A patient with a de novo inversion of chromosome 2 is described. Two of her three children have the same inversion.
Six cases of partial trisomy 1q, including four cases from the literature and our own two observations are summarized with respect to their clinical symptoms. Distinct similarities of the external aspect and of internal malformations allow the delineation of a syndrome of partial trisomy 1q.
Two unrelated families are presented with repeated occurrences of a congenital syndrome of which the main stigmata were polycystic kidneys and occipital encephalocele (Meckel syndrome). Prenatal diagnosis, followed by interruption of pregnancy, was performed in one case. The diagnosis was based on an increase of amniotic alpha-fetoprotein (AFP), and on the mode of growth and cell types of cultured amniotic cells. In another similarly examined case the diagnosis was suspected, but the parents did not wish the pregnancy to be interrupted. The child was stillborn and malformed. AFP values are presented and discussed in relation to the observed malformations. Neural tube defects are associated with an increase of AFP in amniotic fluid, but, as in normal pregnancies, the values decrease with increasing gestational age. On the other hand, kidney malformations seem to be associated with AFP values which remain high or even increase with increasing gestational age.
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