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Biomedical subjects

M Schmid

Publications and source records attributed to M Schmid.

At least 487 records · Page 27Linked to original sources
PubMed1986

Preferential somatic pairing between homologous heterochromatic regions of human chromosomes.

The cytidine analog 5-azacytidine (5-azaC) induces an undercondensation of the heterochromatin in human chromosomes 1, 9, 15, 16, and Y when it is added in low concentrations to the late S-phase of growing lymphocyte cultures. In interphase nuclei, these heterochromatic regions are frequently somatically paired. The somatic pairing configurations are preserved up to metaphase stage in the 5-azaC-treated cultures and are thus susceptible to a direct microscopical examination. The statistical analysis of 1,000 somatic pairing configurations from 5-azaC-treated cells showed that the somatic pairing between the heterochromatic regions of homologous chromosomes is preferred over that between nonhomologous chromosomes.

Azacitidine↗
PubMed1986

[Familial studies of systemic lupus erythematosus. HLA markers and complotypes].

Particular susceptibility to systemic lupus erythematosis (SLE) could be due to a certain alleles of class I, II or III of the major histocompatibility complex (MHC). The existence of total hereditary deficiencies of factor 2 or 4 of the complement in this syndrome suggests the presence of silent alleles which could conceivably play a determining role in the appearance of SLE. In this study, the HLA haplotypes and complotypes (C2, C4, Bf) were determined in 20 individuals suffering from SLE, and compared with 108 healthy, genotyped individuals. The results obtained showed a significant increase in the frequency of C4 BQ0 in patients compared with that found in controls (chi 2 = 12.27, p less than 0.001, Relative Risk = 3.78), and confirm the HLA association, DR3/SLE (chi 2 = 5.45, p less than 0.02, RR = 2.53).

Adult↗
PubMed1985

Familial microtia, meatal atresia, and conductive deafness in three siblings.

We report on three sibs with right-sided microtia, meatal atresia, and conductive deafness. Two of the sibs also had right-sided palatoplegia. These sibs may have the autosomal-recessive form of microtia (No. 25180, McKusick [1983]), of which few familial cases are known to date. The malformation is due to a disturbance of the development of the first and second branchial arches. Review of the literature shows that microtia and meatal atresia with or without middle-ear involvement are developmental field defects which, either isolated or as a part of the facio-auriculo-vertebral spectrum, may occur (1) sporadically, (2) as component manifestation of syndromes, (3) as a multifactorial, or (4) as an apparent Mendelian trait.

Abnormalities, Multiple↗
PubMed1985

Familial paracentric inversion inv(2)(q31q36).

A paracentric inversion of chromosome 2 is described for the first time. The breakpoints were localized in the bands q31 and q36. The paracentric inversion was initially identified in a female with repeated abortions and thereafter detected in eight other family members over three generations. The meiotic consequences and the risk for liveborn unbalanced chromosomal recombinants is discussed.

Abortion, Habitual↗
PubMed1985

A male with a monocentric Yq isochromosome and presence of a Yp-specific DNA sequence.

We describe clinical features and laboratory findings in a physically and mentally retarded male with underdeveloped testes, a seemingly monocentric isochromosome of Yq but the presence of a Yp-specific DNA sequence at a single dose of unknown genomic localisation, and the presence of H-Y antigen at normal male titer. Our data contribute to the fine mapping of the human Y chromosome by correlating phenotypic features with results from karyotypic, immunologic, and molecular hybridisation analyses.

Adolescent↗
PubMed1985

Chromosome banding in Amphibia. IX. The polyploid karyotypes of Odontophrynus americanus and Ceratophrys ornata (Anura, Leptodactylidae).

The somatic and meiotic chromosomes of the South American leptodactylid toads Odontophrynus americanus, Ceratophyrys ornata, and C. cranwelli were analysed both with conventional staining and differential banding techniques. The karyotypes of O. americanus were tetraploid; those of C. ornata octaploid. Ceratophrys cranwelli is a diploid species whose karyotype displays great similarities with that of C. ornata. The high frequency of multivalent pairing configurations in the meioses of O. americanus and C. ornata indicate that these animals were of autopolyploid origin. The conventionally stained somatic chromosomes of O. americanus can be arranged into sets of four similar chromosomes (quartets); those of C. ornata, into sets of eight similar chromosomes (octets). The banding patterns revealed heterogeneity within some quartets of O. americanus, dividing each of them into two pairs of homologous chromosomes. In analogy, some octets of C. ornata can be subdivided into two quartets of chromosomes with homologous bands. These structural heterogeneities within the quartets and octets are interpreted as a "diploidization" of the polyploid karyotypes. Diploidization leads to genomes that are polyploid with respect to the amount of genetic material and diploid with respect to chromosomal characteristics and the level of gene expression. In tetraploid O. americanus, the number of nucleolus organizer regions (NORs) and their DNA content is proportional to the degree of ploidy. In contrast, up to eight NORs have been deleted in the octoploid C. ornata. These NOR losses are discussed as a possible reason for the reduction of genetic activity in polyploid genomes.

Animals↗
PubMed1985

Evolutionary conservation of fragile sites induced by 5-azacytidine and 5-azadeoxycytidine in man, gorilla, and chimpanzee.

Lymphocyte cultures from man, gorilla, and chimpanzee were treated with 5-azacytidine and 5-azadeoxycytidine. These cytidine analogues induce common fragile sites in the chromosome bands 1q42 and 19q13 of man. A rare fragile site is induced by 5-azadeoxycytidine in the band 1q24. The optimum conditions required for inducing these new fragile sites were determined by a series of experiments. The common fragile site in human chromosome 1q42 also exists in the gorilla and chimpanzee in the homologous band 1p32. The fragile site in human chromosome 19q13 was demonstrated in the gorilla in the homologous chromosome band 20q13. These are the first examples found of evolutionary highly conserved fragile sites in homologous chromosome bands in related primate species. The interaction between 5-azacytidine, 5-azadeoxycytidine, and chromosomal DNA; the evolutionary conservation of genes located within or closely adjacent to the fragile sites in the chromosome 1 of Hominoidea; and the phylogenetic origin of the two new common fragile sites are discussed.

Animals↗
PubMed1985

Hepatitis B vaccination campaign in a low endemicity area.

Between January 1982 and December 1983 14,666 high-risk individuals in the Canton of Zurich, which has one million inhabitants, received 36,234 hepatitis B vaccine injections. The annual number of acute hepatitis B cases dropped from an estimated 220 to 280 in 1981 to 177 in 1982 and 133 in 1983. This drop of 40-50% resulted mainly from reduced numbers of cases among health care workers, drug addicts and homosexuals. Vaccination was a factor responsible for the reduced incidence of hepatitis B among health care workers and drug addicts, high-risk categories substantial proportions of which had been vaccinated. There was no evidence of a secondary protective effect of vaccination extending to other high-risk groups.

Hepatitis B↗
PubMed1985

HLA and multiple sclerosis: population and families study.

Association between HLA and multiple sclerosis (MS) was investigated at the population level on 100 MS patients genotyped for HLA-A, B, C, DR and Bf, Glo, and on 155 patients phenotyped for the same HLA antigens. Association between MS and DR2 was clearly confirmed, although its strength is rather weak. No other genetic marker could be related to the disease, no haplotype nor any allelic combination could be recognized as MS specific, and antigen genotype frequencies among the diseased could not ascertain the mode of inheritance, although dominance is very likely. Computer analysis between HLA, Bf, Glo and age of the patient, sex, age of onset and evolution of MS, impairment indexes, titres of anti-DNA and anti-measles antibodies in CSF did not show any interaction. Twenty sib pairs and two trios of MS were also studied; they showed no significant distortion with the random distribution of haplotypes. DR2 gene frequency, however, was significantly higher in sib pairs showing one or two haplotypes than in HLA different affected siblings. Three crossing-overs were identified which suggest where the HLA-linked MS susceptibility (MSS) gene could be located within the HLA segment, while other epistatic MSS genes or environmental factors are likely to be important.

Female↗
PubMed1985

HLA antigens and seronegative rheumatoid arthritis.

HLA antigens and clinical features in a series of 46 Caucasian patients (40 females, 6 males) and definite repeatedly seronegative rheumatoid arthritis (RA) of more than two years' duration (mean 11.6 years) were compared with those in 77 seropositive RA patients and 110 controls of the same ethnic and geographic origin. Seronegative RA appeared to be less often erosive than seropositive RA, and seronegative patients had fewer extra-articular features. The frequency of the HLA antigen DR1 was raised in seronegative patients as compared with controls (p = 0.006, relative risk = 3) and with seropositive patients (p less than 0.05). HLA-DR4 was slightly increased in seronegative patients compared with controls (p less than 0.05) but was clearly less so than in seropositive patients (p less than 0.005). Early onset of disease was very significantly associated with HLA-DR1 in seronegative patients (p = 0.007), whereas HLA-DR4 was present more frequently in seropositive patients with onset prior to age 35 (p less than 0.05). No correlation between HLA antigens and intolerance to drugs was found in seronegative patients, whereas in seropositive patients side effects to gold salts were associated with DR3. These results suggest that seropositive and seronegative RA have distinct HLA-DR associations, especially in disease of early onset, in addition to well established clinical differences.

Adolescent↗
PubMed1985

Cholestasis in alcoholic chronic pancreatitis. Diagnostic value of the transaminase ratio for differentiation between extra- and intra-hepatic cholestasis.

In our long-term study of alcoholic chronic pancreatitis (median follow-up time, 10.4 years) 84 of 173 patients (48.6%) developed transient or persistent cholestasis with or without hyperbilirubinemia. We studied the discriminative value of the ASAT/ALAT ratio to differentiate intrahepatic (IHC) and extrahepatic cholestasis (EHC; due to stenosis of the distal common bile duct) in 75 of these patients. In 45 patients with persistent or recurrent cholestasis (group A) the cause of cholestasis was documented by accurate morphological methods. Thirty of the other 39 patients with transient cholestasis (group B) were classified on the basis of the overall clinical evaluation. Of 37 patients with IHC 36 had an ASAT/ALAT ratio of 1.5 or higher (one patient had normal values for both transaminases). Out of 38 patients classified as EHC 29 had an ASAT/ALAT ratio of 1.4 or lower (9 with normal transaminases being excluded). One patient with cholangitis secondary to EHC had a transient elevation of the ASAT/ALAT ratio to above 2.5. Thus our data suggest that in alcoholic chronic pancreatitis associated with cholestasis an ASAT/ALAT ratio of 1.4 or lower (or normal transaminases) usually indicates EHC. Diagnostic study and surgical decompression is mandatory in these cases if EHC persists.

Alanine Transaminase↗