Biomedical subjects
M Schmidt
Publications and source records attributed to M Schmidt.
Preparation and metabolic characterization of liver parenchymal cells from the pre- and neonatal period.
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Translocation of the nucleolus organizer region to the human X chromosome.
We report the unique finding of a satellited X chromosome in a woman with Turner syndrome and a mosaic karyotype 45,X/46,X,mar(X)(sat,QFQ55),var(21)(sat,QFQ55). In PHA-stimulated lymphocytes and in lymphoblast culture, the satellited X chromosome was consistently late replicating. The translocated nucleolus organizer region (NOR) genes in the stalk of the satellite, however, remained transcriptionally active, and an unusual, late-replicating band was seen at the distal end of Xp. Analysis of fibroblast clones containing the satellited X chromosome suggests that the mar(X) is relatively stable.
Macro-creatine kinase type 1. Immunological studies in 14 patients with comments on clinical significance.
Circulating autoantibodies directed at creatine kinase (CK) BB isozyme are detected in plasma in the form of an immune complex (immunoglobulin CK BB) termed macro-CK type 1. Fourteen patients presented a falsely elevated CK MB isozyme fraction as measured by the immunoinhibition method; they were found to have IgG-CK BB complexes, which was considered to be indirect evidence of circulating anti-CK BB autoantibodies. No evident clinical association between the detection of this autoantibody in complexed form and autoimmune disease could be established, there was no significantly increased incidence of other autoantibodies, and there was no specific alteration in immunoglobulin and complement levels; however, the HLA haplotype A1,B8,DR3, which is known to be associated with autoimmunity, was present in five patients.
Transient hyperphosphatasemia of infancy.
Six patients with transient hyperphosphatasemia of infancy (THI) are described and compared to similar cases reported in the literature. THI appears to be more common than usually thought and may occur in healthy children as well as in patients with various clinical disorders. The evolution of such children seems uniformly normal. Invasive diagnostic procedures should therefore be avoided in this benign condition.
[Preventive chemotherapy in tuberculosis].
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[Questions from clinicians to the radiologist regarding the diagnosis of metabolic bone diseases].
Macromorphological X-ray findings in metabolic bone disease can establish the diagnosis only in advanced stages. Micromorphological X-ray diagnostic procedures will support the diagnosis even at an early stage. Measurement of minerals is an adjuvant method for early diagnosis and survey of therapy in metabolic bone diseases. The measurement of calcium phosphate metabolism and description of bone histology (histomorphometry) and radiological morphology enables the type and stage of osteopathy to be diagnosed. The combination of diagnostic methods is helpful in distinguishing bone diseases with increased turnover, impaired bone modelling and absorption, disturbed mineralization and ectopic calcification. Within the metabolic osteopathies, osteoporosis is gaining importance as a socioeconomic problem; therefore, early diagnosis and treatment are of relevance. Hyper-, hypoparathyroidism and osteoidosis are curable if early diagnosed.
Abdominal surgery in three adult male Asian elephants.
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Number and distribution of putative cholinergic neurons in the cat retina.
The number and distribution of putative cholinergic amacrine cells in cat retina was demonstrated by immunocytochemical localization of choline acetyltransferase (ChAT), the synthesizing enzyme for acetylcholine. In whole mount preparations of the cat retina ChAT-immunoreactive neurons were found in the inner nuclear layer (presumably amacrine cells) and in the ganglion cell layer (presumably displaced amacrine cells). The density of ChAT-labelled neurons increased from about 280 cells/mm2 in peripheral retina, to about 2750 cells/mm2 in the central area. There were always more ChAT-positive cells in the ganglion cell layer (50-70%) than in the amacrine cell layer. Two narrow dendritic strata were labelled in the inner plexiform layer.
Characterization of a high affinity piretanide receptor on kidney membranes.
The tritiated loop diuretic, piretanide, is a useful ligand for specific diuretic receptors which are present in the plasma membranes of renal medullary cells. Its high specific activity (30 Ci X mmol-1) made it possible to demonstrate the existence of a high affinity receptor (Kd approximately 5 nM) and a binding site with low affinity. High affinity binding is saturable, reversible and displaceable by a number of non-radioactive loop diuretics. Structural analogues, devoid of diuretic activity, do not displace piretanide binding. No specific binding occurs in liver or spleen membranes.
Structure and genomic organization of a new family of murine retrovirus-related DNA sequences (MuRRS).
A new class of murine retrovirus-related sequences (MuRRS) is described. These 5.7 kb long transposon-like DNA-elements start and end with approximately 600 bp long repeats identical to previously identified solitary LTR-like elements (LTR-IS). There are about 50 - 100 5.7 kb elements and about 500 - 1000 solo LTR-IS elements per mouse haploid genome. Sequence analysis of one cloned MuRRS element revealed several possible open reading frames with partial sequence homologies to retroviral gag, pol and env genes.
[The role of neutropenia in bacterial infections in children with malignant diseases under cytostatic therapy].
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Cytogenetic findings in a case of Sézary syndrome.
Repeated cytogenetic studies were carried out on a Sézary syndrome patient during a 1-year period. The presence of a single clone of heteroploid (60-86 chromosomes) cells was a permanent finding in the PHA-stimulated blood cultures. The bone marrow was normal. Sister chromatid exchange (SCE) value was relatively lower in heteroploid cells.
[Persistence of antibodies against hepatitis B surface antigens after vaccination against hepatitis B].
In 195 patients vaccinated against hepatitis B the course of anti-HBs concentration was followed over 4 years. Persistence of anti-HBs proved to be dependent on the level of anti-HBs concentration after basal immunization: in 14 subjects with a maximal anti-HBs level between 10 and 100 IU/l the level had dropped to less than 10 IU/l (considered to be the lowest prophylactic concentration), while 7 were anti-HBs negative. Of those who had 101-1000 IU/l after initial immunization 49% had anti-HBs levels under 10 IU/l after 4 years, while 18% were negative. Among subjects with concentrations 1001-10 000 IU/l after the third immunization only 7% had values below 10 IU/l after 4 years, 4.2% were negative. All those who, after the third immunization, had had anti-HBs levels above 10 000 IU/l, 4 years later still had anti-HBs levels of more than 100 IU/l (mean 581 IU/l). Quantitative anti-HBs determination after triple vaccination against hepatitis B thus makes it possible to predict the duration of protection and to determine the timing of re-vaccination.
Immune responses to late booster doses of hepatitis B vaccine.
Nineteen healthy young adults were vaccinated with plasma-derived hepatitis B vaccine at months 0, 1, and 12, and their immune responses were compared to those of a similar group of 20 vaccinees immunized at months 0, 1, and 6. Late booster injections at 12 months produced nearly fivefold higher geometric mean anti-HBs levels than those of the control group. The higher anti-HBs values may lead to longer persistence of anti-HBs and thus to longer protection against hepatitis B.
Evidence for a relationship between DNA methylation and DNA replication from studies of the 5-azacytidine-reactivated allocyclic X chromosome.
We examined the sequence of DNA synthesis of the human active, inactive and reactivated X chromosomes in mouse-human hybrid cells. The two independent reactivants, induced by 5-azacytidine (5-azaC), expressed human hypoxanthinephosphoribosyl transferase (HPRT), and one also expressed human glucose-6-phosphate dehydrogenase (G6PD) and phosphoglycerate kinase (PGK). Restriction enzyme analysis of DNA methylation at the re-expressed loci revealed hypomethylation of CpG clusters, that characterizes the relevant genes on the active X. The transfer of active and inactive X chromosomes from the native environment of the human fibroblast to the foreign environment of the hybrid cell did not affect the specific replication sequence of either human X chromosome. The silent X chromosome when reactivated, remained allocyclic, and the first bands to replicate were the same as prior to reactivation. In one reactivant, however, further progression of replication was significantly altered with respect to the order in which bands were synthesized. This alteration in the replication of the silent X following 5-azaC-induced reactivation suggests that DNA methylation may modulate the replication kinetics of chromosomal DNA.