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Biomedical subjects

M Schweiger

Publications and source records attributed to M Schweiger.

At least 127 records · Page 7Linked to original sources
PubMed1986

Isolation of ADP-ribosyltransferase by affinity chromatography.

An affinity adsorbent for ADP-ribosyltransferase (EC 2.4.2.30) has been synthesized by coupling 3-aminobenzamide to Sepharose 4B. Using this material, ADP-ribosyltransferase from human placenta has been purified from crude extract to homogeneity within a few hours. The enzyme has an apparent Km for NAD+ of 52 microM. Its molecular mass is 115,000 as determined by gel electrophoresis. The enzyme is DNA dependent and stimulated by histone, its temperature optimum is at 25 degrees C, and its pH optimum is around pH 9. alpha-NAD+, thymidine, caffeine, theophylline, theobromine, 3-methoxybenzamide, and nicotinamide inhibit the enzyme. Purification of ADP-ribosyltransferases from horse, rat, and chicken liver was also achieved with the method described.

Animals↗
PubMed1986

The FI gene product of bacterial virus Lambda is related to the E. coli chromosomal protein NS2 and is involved in intracellular DNA organization.

A likely function of the Lambda FI gene product (gpFI) is condensation of developmental forms of the bacteriophage DNA in the host cell. Several characteristics of gpFI support this hypothesis: it is similar in its structure and properties to E. coli NS proteins whose involvement in the bacterial DNA condensation has been established and it comigrates with DNA during fractionation of host cell lysate through a sucrose gradient.

Amino Acid Sequence↗
PubMed1986

Macronutrient intake, plasma large neutral amino acids and mood during weight-reducing diets.

Influence of diet composition on mood during weight-reducing diets was studied in healthy young women of normal weight. A broad range of macronutrient intake was achieved by means of divergent dietary instructions for the composition of a 1,000 kcal per day diet adhered to for six weeks. Global mood during the last three weeks of the diet was significantly better in the "vegetarian" than in the "mixed" diet group. During this time a significant correlation was observed between relative carbohydrate intake and global mood (r = -0.74; p less than 0.01) and between the ratio of plasma tryptophan to other large neutral amino acids (a predictor of tryptophan flow into brain) and global mood (r = -0.52; p less than 0.05). Results suggest that group differences are related to differences in carbohydrate intake. It is hypothesized that impairment of central serotonergic function due to reduced tryptophan availability can prompt mood deterioration in situations of relatively low carbohydrate intake.

Adult↗
PubMed1986

Dieting influences the menstrual cycle: vegetarian versus nonvegetarian diet.

Eighteen healthy, normal-weight women aged 19 to 27 years who had regular ovulatory menstrual cycles volunteered for the study. Blood was drawn on Mondays, Wednesdays, and Fridays throughout the control cycle and during a 6-week diet period that began with commencement of a new cycle. Nine women followed a vegetarian diet and nine a nonvegetarian diet. Both groups lost an average of 1 kg body weight/week. Seven of nine women in the vegetarian group became anovulatory. During the vegetarian diet the average luteinizing hormone (LH) values were significantly decreased during the midcycle and the luteal phase. Estradiol (E2) and progesterone (P) values were significantly lower during the luteal phase. In contrast, the nonvegetarian group did not show significant reduction of LH, E2, and P values during any part of the menstrual cycle. Seven of nine women in the nonvegetarian diet group maintained ovulatory cycles with no changes in cycle length or in the length of the follicular phase. In one woman who became anovulatory, E2 values did not increase during the follicular phase.

3-Hydroxybutyric Acid↗
PubMed1986

DNA repair in human cells: in Cockayne syndrome cells rejoining of DNA strands is impaired.

Fibroblasts from patients with Cockayne Syndrome (CS) are hypersensitive to UV light. DNA repair was analyzed in these cells by sedimentation behaviour of DNA nucleoids in sucrose gradients and compared to normal control cells. The initiation of repair, the incision of the DNA strand next to the UV lesion appeared to be normal. The rejoining of DNA stretches, however, is retarded in CS cells. DNA repair synthesis of UV damages was measured by autoradiography of [14C]thymidine incorporation into resting cells. Up to 4 h the DNA repair synthesis was comparable with normal cells. From 4 to 7 h the incorporation of radioactive precursors declined in CS cells. Besides a defective DNA polymerase this could be due to accelerated excorporation of radioactive nucleotides as a consequence of delayed ligation. In ligation the enzyme itself could be affected as well as its activation by ADP-ribosylation. Nicotine adenine dinucleotide (NAD+) is needed for the ADP ribosylation process. The cellular NAD+ content, however, was found to be the same in normal and in CS fibroblasts. Increase of the extracellular NAD+ supply accelerated the rejoining of UV damaged DNA in CS cells.

Cell Line↗
PubMed1986

Transient expression of a plasmid gene, a tool to study DNA repair in human cells: defect of DNA repair in Cockayne syndrome; one thymine cyclobutane dimer is sufficient to block transcription.

Transfected recombinant DNA with regulatory elements such as eukaryotic promoter and termination sites is transiently expressed in human fibroblast cells. Utilizing an expression vector containing the simian virus 40 (SV 40) early control region followed by the E. coli chloramphenicol acetyltransferase (CAT) gene, we investigated the ability of normal, Xeroderma pigmentosum and Cockayne Syndrome cells to repair UV lesions in transfected DNA. Fibroblasts from Xeroderma pigmentosum patients which cannot excise pyrimidine cyclobutane dimers were unable to restore expression of UV irradiated CAT gene. An UV dose inducing one thymine cyclobutane dimer in the transcribed strand of the CAT gene blocked its transcription in these repair deficient cells. Normal cell were able to repair the lesions in transfected DNA during an incubation period of about 40 h and in this way could overcome the UV block. In several fibroblast cell lines from patients suffering from Cockayne Syndrome expression of UV damaged CAT gene was restored significantly less than in normal fibroblasts, indicating that Cockayne Syndrome is associated with a UV repair defect.

Alkylating Agents↗
PubMed1985

A model of lambda DNA arrangement in the viral particle.

The icosahedral shape of the lambda head suggests a 12-subunit structure of the collapsed DNA inside. The internal space of an icosahedron can optimally be filled by 12 geometrical figures each of which is a combination of a cone and more than half of a sphere. Such a pear-like geometrical figure is, in fact, formed spontaneously by DNA collapsed under certain conditions in vitro (Eickbush & Moudrianakis, 1978). It is proposed that a pear-like structure formed by about 4000 bp is the fundamental structural subunit of packaged lambda DNA. A possible arrangement of the 12 subunits inside the phage head relative to the tail is discussed. We hypothesize that lambda DNA is packaged into proheads in its condensed form. A driving force promoting the DNA translocation could be an ATP-dependent activity of a DNA topoisomerase (gpA/gpNu1), which would induce further reduction in the linking number of the already strongly negatively supercoiled DNA by rotation of one DNA strand around the other. The additional strain accumulated at the end of DNA molecule bound by the topoisomerase beyond a critical value would lead to regional collapse of the viral genome into a pear-like structure.

Animals↗
PubMed1985

Percutaneous transluminal coronary angioplasty--effect of the moveable guide wire on the complication rate.

Beginning with the first percutaneous transluminal coronary angioplasty (PTCA) performed at Baystate Medical Center, 152 consecutive procedures were analyzed. Sixty were done using USCI-G (nonsteerable) series catheters. In two patients both a G and S (steerable) catheter were used. In 90 procedures the S system was used exclusively. Among the attempted angioplasties with the G series catheter, the percutaneous transluminal coronary angioplasty was successful in 47 (78%). Eight coronary occlusions were induced and all these patients underwent coronary bypass surgery. There were no deaths, but three patients (5%) had acute myocardial infarctions (MI). The two patients in whom both G and S catheters were used had occlusions. One went to surgery and died postoperatively of uncontrollable ventricular arrhythmias. The other patient had a myocardial infarction and recovered. Of the 90 attempts with the exclusive use of the steerable system, 75 were successful (83%). Three coronary occlusions were induced in the 90 attempts and two of the patients had coronary artery bypass surgery. None of the three sustained a myocardial infarction. In summary, the proportion of patients requiring emergency surgery was significantly reduced from 13.3% (8 of 60) to 2.2% (2 of 90) (p=0.02), the incidence of myocardial infarction was reduced from 5 to 0%, and there was a slight increase in the siccess rate of the procedure after the introduction of the steerable system. It is concluded that the steerable system increases the safety of PTCA.

Adult↗
PubMed1985

Progressive muscular dystrophy (Duchenne): biochemical studies by flow-cytometry.

The peanut lectin (PNL) receptor density of the cell membrane and several metabolic parameters of cultured fibroblasts of normal human individuals and of patients with muscular dystrophy were measured by simultaneous two and three parameter flow cytometry. The PNL-receptor density was significantly decreased on muscular dystrophy fibroblasts (between 20.7 and 33.6%) as compared to normal fibroblasts. The cell volume, the esterase activity, the intracellular pH, and the percentage of proliferating cells of both types of fibroblasts were not significantly altered. The mean cell volume of different fibroblast cultures varied between 2500 and 6000 micron 3. The concentration of the intracellular esterase activity of fibroblasts was low (0.169 relative units) as compared to lymphocytes and granulocytes of the peripheral blood (1.56 and 2.17 relative units). The fibroblasts had an acidic intracellular pH of 6.52 while lymphocytes and granulocytes had basic pH values of 7.30 and 7.17. Some of the fibroblasts were in the S + G2/M phase of the cell cycle (20%). The study shows that the measurement of biochemical parameters of vital and fixed single fibroblasts by flow-cytometry is of great interest for the recognition of differences between normal individuals and muscular dystrophy patients.

Cell Cycle↗
PubMed1985

Megakaryoblastic micromegakaryocytic crisis in chronic myeloid leukemia.

Atypical megakaryoblasts (MKB) or megakaryocytes (MK) are occasionally present in the peripheral blood during the terminal development of chronic myeloid leukemia (CML). We report on a 49-year-old female suffering from Ph1 chromosome-positive CML with typical megakaryoblastic transformation in the peripheral blood and in the bone marrow. The small "blasts" were at the most only slightly larger and were occasionally even smaller than lymphocytes but showed megakaryoblastic or atypical megakaryocytic differentiation. The cytoplasmic cytochemical pattern of the atypical megakaryocytic cells was identical to that of large atypical thrombocytes. Platelet peroxidase was detected upon electron-microscopic (EM) examination. Immunologic characterization disclosed the presence of MK-specific antigens. When cultured in vitro on agar, the blasts transformed spontaneously into large mature MK, exhibiting characteristic cytochemical and immunological patterns. Cytogenetic examination of peripheral blood showed severe abnormalities. The patient did not respond to therapy and died 3 months after manifestation of the blast crisis.

Bone Marrow Cells↗
PubMed1985

[Colorectal cancer as surgical emergency].

295 out of 3014 patients (9.8%) treated for colorectal carcinoma between 01/1969 and 12/1983 presented as emergencies. The postoperative mortality rate of 28% was high in the emergency group compared with 6% after elective surgery. The tumor stage was far more advanced with 27% distant metastases. The overall 37% 5-year-survival rate was significantly different from that after elective operations (57%, p.o. deaths not included). Differences were statistically not significant when respective UICC-stages were compared.

Colonic Neoplasms↗
PubMed1985

Identification of a high molecular weight polypeptide that may be part of the circadian clockwork in Acetabularia.

In the chloroplast fraction of the unicellular and uninucleate green alga Acetabularia, we have detected a M(r) approximately 230,000 protein (p230) whose synthesis exhibits a pronounced endogenous diurnal rhythm. As judged by scanning densitometry of fluorographs of NaDodSO(4)/polyacrylamide gels, the synthesis of other proteins in the same fraction was independent of the time in the cycle. The incorporation of [(35)S]methionine into p230 was completely inhibited by cycloheximide, whereas chloramphenicol had no effect. This strongly suggests that p230 is translated on 80S ribosomes. Eighthour periods of exposure to cycloheximide produced a shift in the phase of the oscillation of p230 synthesis. The results are consistent with the hypothesis that p230 is essential for expression of circadian rhythms in Acetabularia.

Journal Article↗
PubMed1985

Fibroblasts from patients with Fanconi's anemia are not deficient in excision of thymine dimer.

Fibroblasts from a patient with Fanconi's anemia were reported to show a defective excision of pyrimidine dimer [15]. We developed a sensitive radioimmuno assay which is specific for thymine dimer, the main ultraviolet photoproduct, and reinvestigated the thymine dimer excision in fibroblasts from patients with Fanconi's anemia. The analysis of 7 Fanconi's anemia cell lines did not agree with the claim mentioned above that was derived from only one Fanconi's anemia cell line. All cell lines we studied, including the cell line used previously [15], excised thymine dimer from their DNA with excision rates similar to those of normal fibroblasts. Additionally, in two Fanconi's anemia and in two normal fibroblast cell lines the repair capacity was examined.

Adult↗
PubMed1984

A synthetic hapten for induction of thymine-dimer-specific antibodies.

High specificity and sensitivity of thymine cyclobutane dimer (thy[]thy) detection were obtained by a radioimmunoassay. Attempts to raise thy[]thy-monospecific antibodies with antigens produced according to conventional methods were unsuccessful. Thy[]thy-specific antibodies could only be raised by using a new strategy to bind thy[]thy to protein: thymine was activated by trimethylsilylation and alkylated at N1 yielding N1-thyminebutanoic acid which was dimerised by ultraviolet treatment. The resulting derivative of thymine cyclobutane dimer was coupled to bovine serum albumin by the active-ester method. The new strategy appears to be generally applicable for binding haptens, such as DNA bases, photoproducts etc, to proteins via a derivative containing a carboxyl group. Immunisation of rabbits with the thy[]thy-bovine-serum-albumin conjugate prepared by the new method resulted in a highly specific antiserum which allows detection of thy[]thy down to 0.06 p mol (15pg). The thy[]thy-specific radioimmunoassay was applied to measure thy[]thy formed in human fibroblasts which were exposed to sunlight at altitudes of 600 m or 2300 m. The amounts of thy[]thy formed in an hour corresponded to doses of 14 J m-2 and 24 J m-2, respectively, of an ultraviolet light lamp emitting predominantly 245-nm light.

Animals↗
PubMed1984

[Carcinoma of the colon. Results of surgical therapy].

The results of surgical treatment in 1032 patients with adenocarcinoma of the colon are demonstrated. In 90% a tumorresection was carried out. In 83% this resection was curative. The more advanced cancers could be found in the colon above the sigmoid. Preoperative tumor complications occurred more frequently in this area. The postoperative mortality rate after resektion of colonic carcinomas was overall 8.3% (elective surgery 6.6%; emergency surgery 20%). In the right colon an anastomotic leakage happened in 5.6%, in the left colon in 9.1%. In the right colon this complication was with a mortality rate of 67%, twice as high. The analysis of the survival rates proved that prognosis depends on the tumor stage, not on the location of the colonic cancer.

Adenocarcinoma↗
PubMed1984

Traumatic ventricular septal defect following closed-chest massage: a new approach to closure.

A 59-year-old man underwent a quadruple coronary bypass. Nine hours postoperatively, cardiac arrest developed; it was preceded by bradycardia resistant to pacing. Closed-chest massage resulted in a rapid recovery of stable cardiac function followed by the development of cardiogenic shock. A new systolic murmur was appreciated 36 hours following arrest. It was diagnosed at catheterization as a ventricular septal defect that was subsequently found to lie in the posterior ventricular septum, and two operations were necessary to effect closure. The final operation was performed with exposure of the septal defect through the right atrium. Sixteen months after operation, the patient remained well. To our knowledge, this is the first reported instance of a ventricular septal defect occurring secondary to closed-chest massage and also of the closure of a traumatic defect using a right atrial approach.

Female↗