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991.
Chronic low-frequency stimulation of rat fast-twitch muscle induces 3.7-fold elevations in cytochrome c oxidase activity, but remains without effect on carbonic anhydrase III (CAIII) mRNA and protein. This is in contrast with the situation in the rabbit where chronic stimulation elicits more than 10-fold elevations in CAIII activity and mRNA content which coincide with an enhanced expression of the slow myosin heavy chain (HCI). Since chronic stimulation of rat muscle does not enhance the expression of HCI, we conclude that CAIII is expressed in parallel with HCI and, therefore, is present only in type I and C fibers. 相似文献
992.
I Harbitz B Chowdhary P D Thomsen W Davies U Kaufmann S Kran I Gustavsson K Christensen J G Hauge 《Genomics》1990,8(2):243-248
Several studies point to the possibility that malignant hyperthermia (MH) in pigs is caused by a defect in the calcium release channel (CRC) of skeletal muscle sarcoplasmic reticulum. The locus for MH is closely linked to the glucosephosphate isomerase (GPI) locus, near the centromere of chromosome 6. We demonstrate synteny of the genes for CRC and GPI using somatic cell hybrid lines, and assign the CRC gene to chromosome 6p11----q21 by in situ hybridization. 相似文献
993.
Synopsis The relationship between respiration and swimming speed of larvae and juveniles (2–100 mg fresh mass) of Danube bleak, Chalcalburnus chalcoides (Cyprinidae), was measured at 15° and 20° C under hypoxic (50% air saturation), normoxic, and hyperoxic (140% air saturation) conditions. In a flow-tunnel equipped with a flow-through respirometer the animals swam at speeds of up to 8 lengths · s-1; speeds were sustained for at least two minutes. The mass specific standard, routine, and active respiration rates declined with increasing body mass at both temperatures. Metabolic intensity increased with temperature, but also the critical swimming speed (at which oxygen uptake reached its maximum) was higher at 20° than at 15° C by about 30%. Nevertheless, the oxygen debt incurred by the fish at the highest speeds was about 40%, and the net cost of swimming about 32%, lower at 20° than at 15°C. The standard metabolic rate was more strongly dependent on temperature (Q10 around 2.5) than the maximum active rate (Q10 below 2). Whereas standard and routine respiration rates were well regulated over the pO2-range investigated (8.5–25.8 kPa), the active rates showed a conformer-like pattern, resulting in factorial scopes for activity between 2 and 4. Under hypoxia, the critical swimming speed was lower than under normoxia by about 1.51 · s-1, but the net cost of swimming was also lower by about 30%. On the other hand, hyperoxia neither increased the swimming performance nor did it lead to a further increase of the metabolic cost of swimming. The hypoxia experiments suggest that in response to lowered tensions of ambient oxygen maintenance functions of metabolism not directly related to swimming may be temporarily reduced, leading to increased apparent swimming efficiency under these conditions. The responses of the larvae of Danube bleak to low temperature and low ambient oxygen are discussed in terms of the metabolic strategies by which energy-limited animals meet the challenge of environmental deterioration. 相似文献
994.
Anja Klose Peter Nicholas Robinson Andreas Gewies Lan Kluwe Dieter Kaufmann Annegret Buske Sigrid Tinschert H. Peters 《Human genetics》1998,102(3):367-371
Neurofibromatosis type 1 (NF1) is a common autosomal dominant disorder. It is caused by mutations in the NF1 gene, which comprises
60 exons and is located on chromosome 17q11.2. A total of 170 unrelated NF1 patients were screened for mutations in four exons
by temperature-gradient gel electrophoresis. Preparatory work revealed the presence of a previously uncharacterized intron
(19a) in what was previously designated exon 19; this allowed us to develop assays for genomic mutation screening in the newly
defined exons 19a and 19b. Two novel NF1 mutations were detected: a single-base insertion in exon 19a creating a frameshift,
and a second mutation affecting the splice donor site of intron 20 and leading to skipping of exon 20. A novel BsaBI polymorphism was identified in intron 19a.
Received: 11 August 1997 / Accepted: 13 November 1997 相似文献
995.
Hyperdiploidy and apparent aneusomy in mesothelial cells from non-malignant effusions as detected by fluorescence in situ hybridization (FISH) 总被引:1,自引:0,他引:1
Interphase cytogenetics by fluorescence in situ hybridization (FISH) can be used to detect malignant cells characterized by chromosomal aneuploidy. However, apparent aneusomy in normal "control" tissues has to be considered when using FISH as diagnostic tool. In effusions as model tissue exposed to metastasis, the definition of cut-off levels for background aneusomy by FISH was aimed in this study. Using centromeric probes representing chromosomes 7, 8, 11, 12, 17 and 18, extensive chromosome copy number enumeration by single-color FISH analysis was performed in pleural and ascitic effusions derived from 15 patients with various, non-malignant diseases. In all effusions, cells with gain of hybridization signals for several or all chromosomes tested were found (in up to 1.94% of cells). A consistent finding was high grade hyperdiploidy (>4 centromeric signals). Mesothelial elements mainly contributed to hyperdiploidy in effusions, as demonstrated by a combined analysis of FISH and immunocytochemistry with staining for cytokeratin. Dual-color FISH analysis showed that hyperdiploidy was predominantly corresponding to polyploidization; however, there were always minor cell populations classified as aneuploid by dual-color FISH. In conclusion, stringent criteria have to be applied to distinguish malignancy-related aneuploidy from background aneusomy by FISH. 相似文献
996.
Salmonella infection in its mammalian host can be dissected into two main components. The co-ordinate expression of bacterial virulence genes which are designed to evade, subvert or circumvent the host response on the one hand, and the host defence mechanisms which are designed to restrict bacterial survival and replication on the other hand. The outcome of infection is determined by the one which succeeds in disturbing this equilibrium more efficiently. This delicate balance between Salmonella virulence and host immunity/inflammation has important implications for vaccine development or therapeutic intervention. Novel Salmonella vaccine candidates and live carriers for heterologous antigens are attenuated strains with defined genetic modifications of metabolic or virulence functions. Although genetic defects of different gene loci can lead to similar degrees of attenuation, effects on the course of infection may vary, thereby altering the quality of the elicited immune response. Studies with gene-deficient animals indicate that Salmonella typhimurium strains with mutations in aroA, phoP/phoQ or ssrA/ssrB invoke different immune responses and that a differential repertoire of pro-inflammatory cytokines is required for clearance. Consequently, Salmonella mutants defective in distinct virulence functions offer the potential to specifically modulate the immune response for defined medical applications. 相似文献
997.
Azizbeck Nanaev Kristof Chwalisz Hans-Georg Frank Gaby Kohnen Christa Hegele-Hartung Peter Kaufmann 《Cell and tissue research》1995,282(3):407-421
The trophoblast invasion of uteroplacental arteries in the guinea pig has been studied by means of electron microscopy and immunohistochemisty. To identify trophoblast cells, smooth muscle cells, and endothelial cells, antibodies against cytokeratins, smooth muscle myosin, desmin, and vimentin were employed. Furthermore, the immunohistochemical expression patterns of nitric oxide synthase isoforms (eNOS, mNOS and bNOS) were studied and were compared with the enzyme histochemical staining for NADPH-diaphorase. Dilation of uteroplacental arteries begins prior to day 30, when trophoblast cells that coexpress endothelial and macrophage nitric oxide synthase can be found in the vicinity of the vessels and replace the surrounding peritoneal mesothelium. Trophoblast invasion of the arterial walls and the subsequent wall destruction are only secondary effects. Starting around day 50, the final steps of pregnancy-dependent vessel modifications involve intraarterial trophoblast adhesion to the endothelium and subsequent replacement of the endothelium by the trophoblast cells. These may centrifugally invade the vessel media eventually forming intraluminal plugs. These findings led us to the conclusion that in the guinea pig pregnancy-induced physiological dilation of the uteroplacental arteries is due to the effect of nitric oxide rather than being caused by trophoblast-induced media destruction.Parts of this study were supported by Grant Ka 36017-2 from the Deutsche Forschungsgemeinschaft. 相似文献
998.
Lin Zhang Christian Rittner James M. Sodetz Peter M. Schneider Thomas Kaufmann 《Human genetics》1995,96(3):281-284
Using an exon-specific polymerase chain reaction (PCR) followed by direct DNA sequence analysis we have analyzed the polymorphism of the -chain of the eighth component of human complement (C8) at the DNA level. We found that two common alleles, C8A*A and C8A*B, are characterized by the substitution of a single amino acid (Gln to Lys), which is caused by a point mutation of a single nucleotide (C to A) in exon 3 at position 187 of the mature C8 cDNA sequence. Based on this mutation, an allele-specific PCR was designed detecting the two alleles of C8A. We applied this method to type the C8A polymorphism using DNA samples from a Chinese Han population. The comparison with the data of protein typing of the same samples proved that the described method is efficient and reliable for the identification of C8A genotypes and may be valuable for further application in population studies and forensic science. 相似文献
999.
P M Ford C White H Kaufmann J MacTavish M Pearson S Ford P Sankar-Mistry P Connop 《CMAJ》1995,153(11):1605-1609
OBJECTIVE: To determine the seroprevalence of HIV infection and hepatitis C among inmates of a federal penitentiary for women. DESIGN: Voluntary, anonymous, linked, point-prevalence study involving testing of blood samples for antibodies to HIV and hepatitis C virus. PARTICIPANTS: All inmates of the multilevel security federal Prison for Women, Kingston, Ont., who volunteered to participate in the study. Inmates at this long-stay facility are from across Canada. OUTCOME MEASURE: Seroprevalence rate among participants of antibodies to HIV and hepatitis C virus. RESULTS: Of the 130 inmates available for study 113 (86.9%) agreed to donate a blood sample. One woman (0.9%) was HIV positive; 45 (39.8%) were positive for hepatitis C antibody. CONCLUSIONS: It is possible to obtain a high participation rate in a voluntary, anonymous, linked point-prevalence study in a long-stay penitentiary. The HIV seroprevalence rate of 0.9% is lower than that found in studies in provincial (short-stay) prisons. However, the high rate of antibodies to hepatitis C suggests a significant level of risk behaviour, most likely injection drug use, and suggests the potential for a rapid increase in the rate of HIV infection should the number of newly admitted HIV-positive inmates who use injection drugs rise. 相似文献
1000.
HISTONE PROTEIN TRANSITION IN DROSOPHILA MELANOGASTER : II. Changes During Early Embryonic Development 总被引:2,自引:1,他引:1
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Employing cytochemical methods it was found that during the early embryonic development of Drosophila melanogaster the nuclei contain in sequence two kinds of chromosomal proteins. The cleavage nuclei (as also the pronuclei), until shortly before the blastoderm stage, contain an atypical (or juvenile) histone, stainable with bromophenol blue but not with alkaline fast green. The typical fast green-positive histone appears at the close of the period of the synchronized cleavage mitoses, just before blastulation, when nucleoli are first produced. The amount of DNA of the cleavage nuclei, as determined cytophotometrically, is nearly constant; therefore, the DNA moiety of the nucleohistone complex seems to remain unaffected by the protein shift during embryonic development. The implications of the protein shift in relation to the histone control of gene expression are discussed. 相似文献