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Biomedical subjects

M Schmidt

Publications and source records attributed to M Schmidt.

At least 631 records · Page 35Linked to original sources
PubMed1992

Response of myogenic determination factors to cessation and resumption of electrical activity in skeletal muscle: a possible role for myogenin in denervation supersensitivity.

1. We have prepared probes specific for the chicken myogenic determination genes MyoD, myogenin, myf5, and herculin and have investigated the expression of these genes in response to denervation and acute electrical stimulation in neonate chick muscle, using ribonuclease protection. 2. Upon denervation, herculin mRNA remains essentially unchanged, myf5 transcript levels approximately double, and MyoD message is up-regulated by two- to fivefold. In contrast, the message coding for myogenin, barely detectable in innervated muscle, rises dramatically (approximately 200-fold) on the second day after nerve section; in this respect it resembles acetylcholine receptor (AChR) alpha-, gamma- and delta-subunit mRNAs. Cohybridization experiments reveal that the increase in myogenin mRNA slightly precedes the rise in AChR alpha-subunit message. 3. Electrical stimulation of denervated muscle leads to an immediate decline in myogenin and AChR alpha-subunit mRNAs, with half-lives of less than an hour and approximately 4 hr, respectively; message stability measurements suggest that this is effected through a rapid shutdown of transcription. Messages coding for MyoD, myf5, and herculin decay much more slowly, as a result of slower turnover. 4. Previous experiments have indicated the involvement of a de novo induced (Tsay, H.-J., Neville, C. M., and Schmidt, J., FEBS Lett. 274:69-72, 1990) autocatalytic (Neville, C. M., Schmidt, M., and Schmidt, J., NeuroReport 2:655-657, 1991) transcription factor in the denervation-triggered up-regulation of AChR alpha-subunit expression; the denervation and electrical stimulation experiments reported here are compatible with the notion that myogenin is that factor.

Amino Acid Sequence↗
PubMed1992

Plasmodium falciparum: identification and purification of the phosphoglycerate kinase of the malaria parasite.

Multiplication of the human malaria parasite Plasmodium falciparum within red blood cells is an energy-dependent process and glucose consumption increases dramatically in infected red blood cells (IRBC) versus normal red blood cells (NRBC). The major pathway for glucose metabolism in P. falciparum IRBC is anaerobic glycolysis. Phosphoglycerate kinase (PGK) is one of the key enzymes of this pathway as it generates ATP. We found that the PGK specific activity in P. falciparum IRBC is seven times higher than that in NRBC. The parasitic origin of the increase in PGK activity is confirmed by isoelectric focusing. Indeed, two P. falciparum isoenzymes with neutral isoelectric points were detected. P. falciparum PGK in purified form has a molecular mass of 48 kDa. Antiserum raised against purified P. falciparum PGK specifically recognizes the 48-kDa protein band in P. falciparum and also reacts with P. berghei and P. yoelii IRBC lysates but does not cross-react with PGK associated with NRBC.

Animals↗
PubMed1992

Development of myelinated and unmyelinated fibers of human vagus nerve during the first year of life.

As an important component of cardiorespiratory control, the vagus nerve and its maturation were evaluated in normal infants in order to provide standards of comparison with infants with dysfunctional neural control mechanisms. Myelinated and unmyelinated fibers in the cervical vagus nerve were examined in 27 term infants. Number of fibers, axon diameters, and myelin thickness were compared among four age groups. The histograms of axon size exhibited a skewed distribution that persisted during the age range examined for both myelinated and unmyelinated vagus fibers. Fiber size distributions of myelinated fibers, however, already showed an incipient multimodal distribution after 3 months. No major increase was observed in the average axon size of myelinated and unmyelinated fibers. A significant increase was observed, however, in the average content of myelin in myelinated fibers expressed as myelin thickness, number of lamellae or g ratio (internal/external diameter). These results suggest an active myelination during the first 9 months of life without a major change in the axonal characteristics of the fibers. A marginal increase in the density of myelinated fibers with age, both in terms of total number and the relation to unmyelinated fibers, suggests a slow transition from unmyelinated to myelinated fibers during the first year of life, particularly during the first 3 months. The present morphometric parameters indicate an active deposition of myelin before the maturation of cross-axonal dimensions. The distribution of g ratios also suggests that optimal conduction velocity is compromised only in a fraction of all vagal myelinated fibers.

Aging↗
PubMed1992

Isolation and characterization of a retrovirus from the fish genus Xiphophorus.

A cell line (BsT) established from neoplastic embryonal tissues of the platyfish (Xiphophorus maculatus) released spontaneously retrovirus-like particles. The particles have a buoyant density of 1.16 g/ml, a mean diameter of 100 nm and the morphology of immature retroviruses. The particle-associated proteins p70, p65, and p28 react with an antiserum directed against the major internal feline leukemia virus structural protein p27. The particles are associated with a reverse transcriptase. The purified enzyme has a molecular weight of about 70 kDa and prefers the template primers poly(rA):oligo(dT), poly(dC):oligo(dG), and poly(rC):oligo(dG) in the presence of Mn2+. The enzyme activity is inhibited by antibodies directed against the reverse transcriptase of feline leukemia virus and simian sarcoma virus. The particles contain a ribonucleic acid of about 70 S. In an endogenous reverse transcriptase reaction nucleic acids in the range of 0.2 to 0.4 kb were synthesized. In Northern blots with these nucleic acids as probe, three transcripts of about 8.5, 4.2, and 1.5 kb were detected in BsT cells. Southern blot analysis with the same probe demonstrates related sequences in the DNA of BsT cells and the platyfish and swordtail (Xiphophorus helleri). Hybridization experiments with the LTR-gag region of the feline leukemia virus show homologous sequences in the Xiphophorus genome.

Animals↗
PubMed1992

The freezability of biopsied bovine embryos.

A biopsy of 1-5 blastomeres was taken from 86 bovine compacted morulae, using a technique, that did minimal damage to the zona pellucida. As soon as possible after the micromanipulation the embryos were frozen, without sealing the penetrated zona pellucida. In order to evaluate the viability of the biopsied frozen-thawed embryos, half of them were transferred to synchronized recipients while the remaining half were co-cultured to evaluate the developmental capacity. A control group of 43 intact embryos was subjected to the same procedures. This study revealed a slight, but not significant, decrease in the pregnancy rate of the biopsied embryos after freezing and thawing, although the embryos by co-culture with bovine oviduct epithelial cells revealed normal morphology and developmental rate. It is concluded that the described biopsy technique did not compromise the freezability of 7-day-old bovine embryos.

Journal Article↗
PubMed1992

Identification and purification of glucose phosphate isomerase of Plasmodium falciparum.

The multiplication of malaria parasites within red blood cells is energy dependent. Since these parasites lack a functional tricarboxylic acid cycle, the energy needs of the parasite are met by anaerobic glycolysis of exogenous glucose. High levels of glycolytic enzymes such as fructose-1,6-diphosphate aldolase, phosphoglycerate kinase and pyruvate kinase have been detected in infected erythrocytes. Here we report a 4-9 times increase in glucose phosphate isomerase (GPI) activity of infected erythrocytes over that of normal erythrocytes. This increase is of parasitic origin, as additional enzyme bands were observed in lysates of infected erythrocytes. The expression of GPI parallels parasite maturation and reaches a maximum at the trophozoite/schizont stage. Two distinct but closely related activity patterns consisting of 3-4 GPI isoenzymes (not shown in normal erythrocytes) with neutral to weakly acidic isoelectric points were observed in 6 P. falciparum isolates tested by isoelectric focusing. The purified P. falciparum GPI has an apparent size of 66 kDa. No size variation was observed in the 6 P. falciparum isolates studied. Furthermore, antiserum raised against this protein in BALB/c mice specifically inhibits parasite encoded GPI activity while no effect was observed on host enzyme activity.

Animals↗
PubMed1992

Vaccination against hepatitis A: comparison of different short-term immunization schedules.

A total of 114 healthy young adults were immunized with hepatitis A vaccine using different vaccination schedules. Individuals received either a single dose (group 1), two doses given simultaneously (group 2), two doses at days 0 and 14 (group 3) or at days 0 and 28 (group 4), or three doses at days 0, 7 and 21 (group 5). Two weeks after a single dose, seroconversion rates between 77 and 85% were achieved (groups 1, 3, 4). All individuals immunized with two doses within two weeks (groups 2, 3, 5) had antibodies to hepatitis A vaccine (anti-HAV positive) by week 3; these participants also showed clearly higher mean anti-HAV values (geometric mean titres, GMTs) at this time than those individuals vaccinated only once. GMTs at week 8 were 560 IU/l in group 5, 236, 339 and 428 IU/l in groups 2-4 and 102 IU/l in group 1. Of participants with anti-HAV at week 8, 82 were again tested 4 months later; all were still seropositive. Ten individuals were tested during the first three weeks at 3-4 day intervals for anti-HAV immunoglobulin M (IgM); specific IgM responses were not detectable before day 10 but were present in eight of 10 vaccinees by day 14.

Adult↗
PubMed1992

Comparison of the anti-emetic efficacy of different doses of ondansetron, given as either a continuous infusion or a single intravenous dose, in acute cisplatin-induced emesis. A multicentre, double-blind, randomised, parallel group study. Ondansetron Study Group.

A total of 535 chemotherapy naive, hospitalised patients (263 male/272 female) scheduled to receive cisplatin (50-120 mg m-2)-containing regimens participated in a randomised, double-blind, parallel group study to evaluate the efficacy and safety of three intravenous dose schedules of ondansetron in the prophylaxis of acute nausea and emesis. One hundred and eighty two patients received a loading dose of 8 mg of ondansetron followed by a 24 h infusion of 1 mg h-1 (group 1); 180 and 173 patients received single doses of 32 mg (group II) and 8 mg (group III) respectively, followed by a 24 h placebo infusion. Complete and major control (less than or equal to 2 emetic episodes) of acute emesis was achieved in 74% of patients in group I, 78% in group II and 74% in group III. Seventy seven per cent of the patients in group I, and 75% of patients in groups II and III respectively experienced no or mild nausea during the 24 h observation period. A retrospective stratification of the efficacy data on the basis of patient gender showed the response rate in females to be significant lower (43% vs 67%; less than 0.001). Ondanestron was well tolerated; mild headache was the most commonly reported adverse event (11% of patients) with a similar incidence in the three groups of patients. In conclusion, a single intravenous dose of 8 mg of ondansetron given prior to chemotherapy is as effective as a 32 mg daily dose given as either a single dose of a continuous infusion in the prophylaxis of acute cisplatin-induced emesis.

Adult↗
PubMed1992

Activity of some lysosomal enzymes in plasma and leucocytes of rabbits exposed to effect of retinol and hydrocortisone.

Observing activity of some lysosomal enzymes in blood serum and leucocytes of rabbits subjected to injection of 200,000 units of retinol and 25 mg of hydrocortisone/kg of body weight it was found that: 1. In the effect of retinol administration there was an increase in the activity AP, BGAL, BGLU, AspAT and lipase in blood serum after 72 hours and NAGL after 168 hours while in leucocytes BGAL and NAGL after 72 hours and AGAL after 168 hours. 2. As a result of hydrocortisone injection the activity of all the enzymes examined (except Ala-Na) in blood serum increased markedly already after 24-48 hours. 3. In leucocytes hydrocortisone caused a significant increase in the activity of AP, BGRD, NAGL, BGAL, AGAL and cathepsin D. 4. The glucose level in blood plasma decreased after 48 hours and 120 hours after hydrocortisone injection and 168 hours after retinol injection.

Animals↗
PubMed1992

An intriguing Y chromosome in Heteromys anomalus (Rodentia, Heteromyidae).

The mitotic chromosomes of the pocket mouse Heteromys anomalus (Rodentia, Heteromyidae) from Venezuela were analyzed by means of conventional staining and various banding techniques. The karyotype of this species is distinguished by a Y chromosome with exceptional banding properties. The very large heterochromatic Y long arm shows a remarkable bright quinacrine fluorescence, but only moderate or dull fluorescence when labeled with other AT base pair-specific fluorochromes. The implications of these findings are discussed.

Animals↗
PubMed1992

Minute Y chromosome derived marker in a child with gonadoblastoma: cytogenetic and DNA studies.

A 12 year old girl referred for chromosome analysis because of short stature was found to have karyotype mos 45,X/46,X,+mar. The marker chromosome was observed in 58% of her blood lymphocytes. It was a small, pale staining, spherical fragment with GTL banding and showed faint differentiation along its length with CBG banding. DNA analysis using Y specific probes showed the absence of the testicular determining region and the presence of some short arm and centromeric Y chromosomal material. In situ hybridisation confirmed that the Y chromosomal material was associated with the marker chromosome. At laparotomy the patient was found to have streak gonads. Gonadectomy was subsequently performed and histological examination showed dysgenetic gonads with a dysgerminoma arising from a gonadoblastoma in the left gonad. This case shows that even very small Y derived marker chromosomes with pericentric material can predispose the phenotypic female to gonadal neoplasia.

Base Sequence↗
PubMed1992

[Results of surgical management of scapula fractures. 78th Annual Meeting of the Swiss Society of Accident Surgery and Occupational Diseases, 4-5 September 1992 in Olten].

The follow-up of 8 patients with scapular fractures showed a high rate of complications with 3 infections and problems with the osteosynthetic material. This did not effect the results in any case, most results were good. The indication for the operation should be proved restrictively, the following operative treatment should be minimal invasive. CPM-devices were used after operation and had a positive effect.

Adult↗
PubMed1992

Specific and sensitive measurement of FK506 and its metabolites in blood and urine of liver-graft recipients.

A specific and sensitive assay for quantifying the immunosuppressant FK506 and its metabolites in blood and urine was developed. 32-O-Acetyl FK506 was synthesized and used as internal standard. FK506 and its metabolites were purified from the samples by solid-liquid extraction and were injected into a high-performance liquid chromatographic (HPLC) system linked to a mass spectrometer (MS) by particle-beam interface. The FK506 derivatives were separated from interfering material by use of a 100 x 4 mm C8 analytical column and water/acetonitrile or water/methanol gradient elution; they were detected by negative chemical ionization with methane as reagent gas. The limit of detection was 25 pg in a standard solution, and the limit of quantification in blood was 250 pg (extracted from 1 mL of blood). The CV was 11.3% at 5 ng, and no interferences with other drugs were found.

Chromatography, High Pressure Liquid↗
PubMed1992

Immunoglobulin prophylaxis during intensive treatment of acute lymphoblastic leukemia in children.

60 children with acute lymphoblastic leukemia were sequentially randomized at the time of diagnosis: Immunoglobulin (Endobulin, Immuno) was administered intravenously to 30 patients at a dose 100 mg/kg/week during the first 3 months, followed by 2 x 200 mg/kg/month immunoglobulin during the 4., 5., 6. months. No immunoglobulin was administered to the control patients. We studied the effect of immunoglobulin prophylaxis on the number of days with fever, number of cases with bacteriologically proved infections, length and frequency of antibiotic therapy. Our data confirm the efficacy of immunoglobulin prophylaxis during the intensive phase of leukemia therapy in children.

Child↗
PubMed1992

[Concentration of Fe, Fe-binding capacity, Cu and Zn in the plasma of piglets before and after oral administration of iron sulfate solution].

In piglets, the influence of the ingestion of Fe-enriched faeces, of the oral application of Fe-dextran (containing 150, 200 or 250 mg Fe) up to the 8th hour as well as the intramuscular injection of Fe-dextran (150 mg Fe) on the 2nd and 3rd day after birth on Fe-resorption was analysed. On the 5th to the 7th and on the 12th to the 14th day after birth the highest increase in the Fe-concentration and the highest values of the Fe-binding capacity of the plasma after the oral application of a solution of Fe-sulphate (containing 20 mg Fe/kg body weight) were confirmed in the piglets with the ingestion of Fe-enriched faeces and in the control piglets without Fe-supplementation. The increase of the iron concentration in the plasma induced a decrease in the concentration of Cu in some cases and of Zn in the plasma in most cases. The biggest increase in body weight was established in the piglets that ingested Fe-enriched faeces.

Administration, Oral↗
PubMed1992

Coculture of bovine demiembryos prior to freezing.

Pregnancy rates after transfer of frozen/thawed bisected embryos, demiembryos, have until now been very low. In the present study it was attempted to improve the freezability rate of demiembryos by culturing them on a monolayer of bovine oviduct epithelial cells (BOEC) prior to freezing. The cultured frozen/thawed demiembryos showed a lower developmental rate than intact embryos. The pregnancy rate (23%) following transfer was not different from the pregnancy rate after transfer of unfrozen demiembryos (26%). The calving rate (4%), however, was significantly lower than the calving rate after transfer of fresh demiembryos (23%). Although the overall pregnancy rate achieved in this study was low, it can be concluded that a co-culture period upon BOEC prior to freezing does not improve the viability of frozen demiembryos.

Animals↗