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Biomedical subjects

M Anton

Publications and source records attributed to M Anton.

At least 73 records · Page 4Linked to original sources
PubMed1991

Functional analysis of a C-terminally altered TonB protein of Escherichia coli.

Deletions within the 3'-end of the cloned Escherichia coli tonB gene were constructed and recombined into the chromosome. Deletions affecting the last eight C-terminal amino acids (aa) yielded functionally active TonB, whereas deletion of the last 15 C-terminal aa, which removed the C-terminal hydrophobic region of TonB, abolished TonB function entirely. Distribution of TonB within cell compartments was not significantly affected by any of the deletions. All deletion derivatives were less stable than wild-type TonB. A major degradation product of approx. 29 kDa was observed for all TonB derivatives, indicating that it was an N-terminal fragment. The possibility is discussed that the C-terminal hydrophobic region is involved in the intramolecular interaction rather than in the membrane association of TonB.

Amino Acid Sequence↗
PubMed1991

Histological grading and DNA content as predictors of distant metastases in squamous cell carcinoma of the uterine cervix.

Squamous cell carcinoma of the uterine cervix with distant metastases can be treated by adjuvant chemotherapy. The at-risk patients are those with histologically proven metastases, the presence of tumour in paracervical tissue and parametrium, evidence of vascular invasion, a great depth of invasion, or poor tumour differentiation. Our studies lead us to believe that differentiation and DNA content are also important criteria.

Aneuploidy↗
PubMed1990

Oxygenation of mitochondrial membranes by the erythroid lipoxygenase. Consequences for membrane properties.

The reticulocyte lipoxygenase is able to oxygenate mitochondrial membranes. The main products formed during this reaction are 15S-hydroperoxy-5Z,8Z,11Z,13E-eicosatetraenoic acid (15-HETE) and 13S-hydroperoxy-9Z,11E-octadecadienoic acid (13-HODE). The oxygenation of mitochondrial membranes is accompanied by an inactivation of enzymes localized in the outer and inner mitochondrial membranes, by a drastic change of the passive electric properties and by a destruction of the iron-sulfur clusters of the outer mitochondrial membrane. The possible mechanism of the processes leading to these functional changes is discussed.

Animals↗
PubMed1990

[The effect of general anesthesia on the position of the eye].

In 100 children operated on account of strabismus the authors tried to assess whether changes in the position of the eyeballs during general anaesthesia with the stretch test can contribute towards the decision on the magnitude of the surgical operation. At the same time they compared changes in the position of the eyeballs during intubation anaesthesia by means of nitrous oxide and halothane with anaesthesia with ketamine, administered by the i.m. or i.v. route. They found that in 92% of the examined subjects the position of the eyeballs changed during general anaesthesia, most frequently the convergent deviation diminished. During ketamine anaesthesia the changes were more marked. The stretch test was in 73% of the patients normal, in 93% it was equal in both eyes. Based on the results, the authors conclude that neither the evaluation of changes of the eyeballs during general anaesthesia nor the stretch test can make the dosage of the surgical operation in concomitant strabismus more accurate.

Anesthesia, General↗
PubMed1990

[Mesodermal dysgenesis].

The authors present an account on a 12-year-old girl with ectomesodermal dysgenesis of the Rieger type syndrome. The disease was manifested at the age of nine months by transient diffuse corneal opacity, while the intraocular pressure was normal. In addition to typical corneal changes and changes in the angle of the chamber other associated somatic symptoms included megalocornea, high myoptic astigmatism, cleft soft palate, hypoplasia of the upper jaw, partial anodontia, marked thoracic kyphosis, scoliosis, generalized hypermobility and taxicity of the joints and torticollis. Examination revealed an uncommon pathological karyotype 46, XX, t/1,4 (p36, q23). Cytogenetic examination of the parents and siblings of the proband did not disclose any numerical or structural aberrations. The authors reflect on possible causes of the development of the disease and on the differential diagnosis.

Abnormalities, Multiple↗
PubMed1989

Oxygenation of mitochondrial membranes by the reticulocyte lipoxygenase. Action on monoamine oxidase activities A and B.

Incubation of isolated rat liver mitochondria with the pure rabbit reticulocyte lipoxygenase caused a time-dependent inactivation of the monoamine oxidase activities A and B. Furthermore, a conversion of the monoamine oxidase into a diamine oxidase was observed. The inactivation kinetics for both monoamine oxidase activities A and B showed a biphasic behaviour; a reversible short-term inhibition during the first 5 min of incubation was followed by an irreversible inactivation of the enzyme. The kinetic studies suggest that the slow irreversible inactivation of the monoamine oxidase activities is due to secondary reactions subsequent to the initial attack of the lipoxygenase on the mitochondrial outer membrane. During the interaction of the lipoxygenase with the mitochondria, only about 1.5% of the polyenoic fatty acids present in the mitochondrial membranes were oxygenated. The predominant products formed during the interaction of the lipoxygenase with the mitochondrial membranes are (13S)-hydro(pero)xy-9Z,11E-octadecadienoic acid and (15S)-hydro(pero)xy-5,8,11,13(Z,Z,Z,E)-eicosatetraenoic acid.

Animals↗
PubMed1989

Schistosoma mansoni antigens recognized in Biomphalaria glabrata hemolymph by monoclonal antibodies.

In order to identify and characterize Schistosoma mansoni antigens in Biomphalaria glabrata, we examined 19 murine monoclonal antibodies (Mabs) for specific binding to schistosome larvae. None of the murine Mabs induced by infection or by immunization with a crude cercarial antigen (CCA) served this purpose. Two Mabs out of 9 (KCSme22-3 and KCSme22-4) induced by soluble egg antigens reacted with CCA but not with normal snail (NSN) extract. We selected these 2 for studies on detection and characterization of schistosomal antigens in snails. When employed in an ELISA, they differentially detected schistosomal antigens in extracts and cell-free hemolymph (plasma) of infected snails. The selected Mabs bind to cercarial surface as demonstrated by the indirect fluorescent antibody technique (IFAT) with paraformaldehyde-fixed cercariae. The epitopes corresponding to the selected Mabs are periodate sensitive, suggesting the glycoprotein nature of the antigens recognized. Immunoblotting analysis employing the selected Mab revealed 1 antigen in CCA (Mr = 205 kDa) and 3 antigens in snail plasma (Mr = 220 kDa, 180 kDa, and 135 kDa). Schistosomal antigens were first detectable in the snails' plasma 2 weeks after snail infection, and their quantity increased afterwards.

Animals↗
PubMed1989

[Intraperitoneal administration of high doses of cisplatin in advanced ovarian carcinoma].

42 patients with advanced ovarian carcinoma were treated with large doses of cis-DDP by the i.p. route. The toxic effects of platinum were reduced by the i.v. administration of thisulphate. Depending on age and the general condition of the patient, 200-270 mg cis-DDP were administered in one series. Ascites disappeared in 54.7% patients, partial remission of the tumour was achieved in 28.5%, complete histopathological remission confirmed by second look operation in 26.2% and in 21.4% the result was doubtful.

Adenocarcinoma↗
PubMed1988

Erythropoietin-induced polycythemia in athymic mice following transplantation of a human renal carcinoma cell line.

An established cloned human renal carcinoma line RC-1, which has been continuously maintained in culture for several years and which produces erythropoietin, was injected s.c. into BALB/c athymic mice and produced tumors. Tumorigenicity was directly correlated with the number of RC-1 cells inoculated. Tumor cell histology resembled the original patient-derived tumor. Tumor-bearing mice developed hepatosplenomegaly and significant reticulocytosis with elevated hemoglobin and hematocrit values that were proportional to tumor mass. In addition, red cell mass and blood volume of nude mice increased over 100% as compared to control mice or to animals bearing nonrelevant neoplasms. Large amounts of immunoreactive erythropoietin could be extracted from the nude mouse RC-1 tumors. These results indicate that the RC-1 cell line is tumorigenic and produces biologically active erythropoietin in vivo in athymic mouse hosts, thus providing a reproducible model to study ectopic erythropoietin production and its regulation in vivo.

Animals↗
PubMed1984

Probable role of endogenous endotoxins in hepatocytolysis during murine hepatitis caused by frog virus 3.

Three new observations bear out the role of endogenous endotoxins in the pathogenesis of murine hepatitis caused by frog virus 3. First, the LD50 of endotoxin is 20 times lower in mice pretreated for 2.5 hr with a sublethal dose of frog virus 3 than in untreated mice. Animals inoculated with one sublethal dose of lipopolysaccharide 2.5 hr after injection of one sublethal dose of virus die, all having developed extensive hepatocellular necrosis. This hypersensitivity varies according to the intensity of virus-induced destruction of Kupffer cells, which are the intrahepatic target of the virus. Second, mortality is significantly lower and the interval between infection and death longer in axenic mice, which are largely protected from portal endotoxemia. Third, the impairment of some biologic activities of endotoxin (through treatment with polymyxin B or indomethacin, for example) protects mice against hepatic damage and death. Likewise, mice rendered tolerant to endotoxins, and C3H/HeJ mice, which are genetically resistant to endotoxins, survive challenge with frog virus 3 and are refractory with regard to hepatocytolysis . These findings suggest that, in hepatitis caused by frog virus 3, endogenous endotoxins are responsible for extensive hepatocytolysis since virus-induced damage to the hepatic reticuloendothelial system prevents their detoxification.

Animals↗
PubMed1983

Lipoxygenase from rabbit reticulocytes: iron content, amino acid composition and C-terminal heterogeneity.

Purified lipoxygenase from rabbit reticulocytes contains 1 g atom iron per molecule. The amino acid composition shows that the enzyme contains 11 cysteine residues but no disulfide bridges and contains a relatively high content of hydrophobic amino acids. The enzyme shows heterogeneity in the C-terminus. With the tritium labeling method the amino acids His, Asn and Ile were found in the C-terminal region. The absorption co-efficient was found to be 1.68 (E0.1% 280 1 cm) in the native state and 1.77 in the unfolded state.

Amino Acid Sequence↗
PubMed1982

Sensitization of mice to methylphenidate.

Mice that received five daily injection of methylphenidate HCl, 10-75 mg/kg, showed an increased running response to methylphenidate, cocaine, and amphetamine. Sensitization to methylphenidate persisted for at least 50 days. Repeated IP injections of methylphenidate into mice with unilateral striatal lesions increased ipsilateral turning in response to methylphenidate, but decreased contralateral turning after apomorphine. The climbing response to apomorphine in intact, methylphenidate-sensitized mice was also decreased. There was no change in either basal or dopamine-stimulated adenyl cyclase activity in the striata of sensitized mice, but there was a 36% increase in the specific binding of haloperidol. The rate of turnover of striatal dopamine was increased in sensitized mice. These results suggest that pretreatment with methylphenidate may alter the sensitivity of presynaptic dopamine receptors.

Adenylyl Cyclases↗