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Biomedical subjects

A Becker

Publications and source records attributed to A Becker.

At least 37 records · Page 2Linked to original sources
PubMed1991

Gangliosides improve a memory deficit in pentylenetetrazol-kindled rats.

Epileptic patients often show impairments in a number of cognitive functions. Kindling is considered to be a useful experimental model for human epilepsy. Recently we have demonstrated a learning impairment in a shuttle box experiment in pentylenetetrazol (PTZ)-kindled rats. This model offers the possibility to investigate the relation between repeated convulsions and their consequences on learning and on the other side to test the effectiveness of substances on both processes. Although systemic application of gangliosides has neither an effect on the development of seizures induced by repeated injections of PTZ, nor on seizures induced by PTZ in kindled animals, the treatment protects against the memory-impairing effect of convulsions. These findings suggest a new useful strategy in the therapy of epileptic patients with the aim of diminishing the psychosocial problems in persons with seizure disorders: a combination of the anticonvulsive basic therapy and gangliosides.

Animals↗
PubMed1991

Pharmacological effects on two inbred substrains of AB mice.

Mice of the two substrains AB/Gat and AB/Hal from the Jena AB inbred strain differ in behavior from each other by their aggressiveness occurring especially in the latter group after maturity. In order to ascertain the neurobiological background of aggressiveness, we injected mice of both substrains with either haloperidol, diazepam, or hexobarbital and measured their response on motor activity. In a second experiment, the reaction to a seizure evoking agent (pentylenetetrazol) was determined. Mice of both substrains were found to differ significantly in their reaction to haloperidol or diazepam injection. In contrast to that no changes in motor activity could be detected following hexobarbital administration. Animals of the aggressive AB/Hal substrain reacted more pronounced to pentylenetetrazol than those of the AB/Gat group. In conclusion, the varying aggressiveness of both AB mice substrains may be due to differences in dopaminergic and GABAergic neurotransmission.

Aggression↗
PubMed1991

Pattern of NADPH-diaphorase active neurons in rat forebrain is unchanged after pentylenetetrazol kindling.

The activity of NADPH-diaphorase in rat telencephalic structures has been revealed by use of a histochemical method. Multiple neurons belonging to different nuclei were found to contain the enzyme. Furthermore, diaphorase reactive nerve fibres and terminal fields were observed to be widely distributed throughout rat brain. Chemical kindling induced by pentylenetetrazol (PTZ) did not effect the regional distribution and cellular localization of the enzyme in the rat CNS.

Animals↗
PubMed1991

Poor development of outer dense fibers as a major cause of tail abnormalities in the spermatozoa of asthenoteratozoospermic men.

For a reasonable analysis of sperm motility, consideration should be given to the morphology of the flagellum. Among various tail disturbances, the present paper describes a structural shaft defect that is characterized by variations in diameter, poor outline and/or lacking endpiece. Electron microscopical examinations, especially the negative staining technique, have shown that in addition to membrane alterations there is one essential cause for the limited extension of the outer dense fibres. This disturbance may be of genetic origin or due to toxic or inflammatory influences. Further molecular biological studies are required to detect the actual cause of this defect, for which there is so far no adequate therapy.

Humans↗
PubMed1991

[Laser Doppler in angiology: clinical relevance or expensive game?].

The analysis of 55 articles about the Laser-Doppler in Angiology with a total of 2425 patients and controls shows very promising results concerning the applicability in daily clinical medicine. However, to establish the method as a basic-test in angiology and vascular surgery, standardized procedures and provocation-tests should be developed in future prospective trials.

Arterial Occlusive Diseases↗
PubMed1991

[Radiologic and clinical follow-up of central venous indwelling catheters in home parenteral nutrition].

In the course of three weeks we examined 42 patients with central indwelling venous catheters for HPN clinically and radiologically for the development of catheter-related complications. Mean patient age was 48 years. In total 47 catheters were implanted. Their mean dwelling time was 37 weeks with the total dwelling time of all catheters amounting to 1773 weeks. In 26%, obstruction of the upper venous systems was the most frequent clinical catheter related complications. However, radiographs showed thrombotic changes on the vessel walls and/or catheter tips in 51%. In the total survey, 66% of the catheters dislocated from the original application site. Overall, 30% of the catheters dislocated into a peripheral vein. The high flexibility of the silicone catheter is probably responsible for this high dislocation rate. Malposition of the catheter represents a major risk in the development of thrombosis and obstruction of the upper venous system. As the catheter is necessary for the patients' survival and the position of the catheter can be corrected after placement we think that routine chest x-rays should be done at least every four weeks.

Adolescent↗
PubMed1991

[Perioperative use of antibiotics for preventive indications].

The prevention of infections in surgical patients undergoing an operation is a major challenge. One of the several possibilities is the administration of appropriate antibiotics during the perioperative period. For this type of prophylactic use the agent selected should be given before contamination--a single dose is very often sufficient. Common indications for antibiotic prophylaxis are: operations involving a high chance of contamination and those that have hither to be clean but in which the implications of infections would be highly threatening.

Anti-Bacterial Agents↗
PubMed1991

Modulation of the antinociceptive effect of morphine by casomorphin derivatives.

Some D-amino acid-substituted derivatives of bovine beta-casomorphin1-5 (CM) were found to share a particular affinity to central opioid receptors. As far as the antinociceptive potency of CM derivatives and their ability to produce tolerance is concerned, possible interactions of two selected CMs (Tyr-Pro-Phe-D-Pro-Gly, D-Pro4 and Tyr-Pro-D-Phe-Pro-Gly, D-Phe3) with morphine and, moreover, the doses necessary to induce tolerance were studied. Antinociception was tested by using the hot-plate test in experiments with mice. It was found that both CMs injected in doses up to 1 mumol/kg were not able to produce any sign of antinociception. It is all the more so interesting since such non-antinociceptive doses of D-Phe3 decreased analgesia induced by 15 mumol/kg morphine significantly. This could be regarded as a consequence of delta-receptor occupation by D-Phe3 and a resulting shift in the mu-receptor-mediated signal transduction. Finally, we found that repeated applications (once daily over a period of 20 days) induced a detectable tolerance to morphine. This suggests that opioid analgesia and tolerance must not be mediated by the same mechanisms and, moreover, that the mechanisms responsible for the development of tolerance are able to react more sensitive to an opioid.

Amino Acid Sequence↗
PubMed1991

[Electron microscopy findings in human spermatozoa with flagellar defects].

Spermatozoal motility disorders must be interpreted with reference to whether the flagella are intact or impaired. A new classification of alterations of midpiece and flagellum includes a shaft disturbance that is increasingly often observed and can be recognized by light microscopy. Electron microscope examinations have shown that missing or poorly developed outer dense fibres are one cause of this flagellar disorder. As suitable longitudinal sections are rarely obtained in transmission electron microscopy, the negative staining technique was used in addition for this purpose. This method was found to be most suitable for an exact analysis of the periaxonemal structures of the sperm flagellum. Consideration of this hitherto unknown flagellar disturbance is important, because various therapeutic approaches have had little success so far and patients should be referred in good time for other gynaecological or andrological treatments.

Cell Membrane↗
PubMed1990

Tissue- and species-specific expression of cytochrome c oxidase isozymes in vertebrates.

Cytochrome c oxidase was isolated from brown fat tissue of the rat and compared with the isozymes from rat liver and heart, which differ at least in subunits VIa and VIII. ELISA titrations of COX from the three tissues with monospecific antisera to all 13 subunits of the rat liver enzyme showed differences between the three enzymes. The N-terminal amino-acid sequence analysis of subunits VIa and VIII from SDS-PAGE gel bands of the three enzymes indicates the occurrence of three different isozymes in the rat. N-terminal amino-acid sequence analysis of subunits VIa and VIII from cytochrome c oxidase of bovine and human heart demonstrates also species-specific differences in the expression of the 'liver-type' and 'heart-type' of subunits VIa and VIII.

Adipose Tissue, Brown↗
PubMed1990

Cloning and expression of a membrane antigen of Entamoeba histolytica possessing multiple tandem repeats.

Entamoeba histolytica causes amebic dysentery and amebic liver abscess, major causes of morbidity and mortality worldwide. We have used differential hybridization screening to isolate an E. histolytica-specific cDNA clone. The cDNA was found to encode a serine-rich E. histolytica protein (SREHP) containing multiple tandem repeats. The structural motif of SREHP resembles some of the repetitive antigens of malarial species, especially the circumsporozoite proteins. A recombinant trpE fusion protein containing the tandem repeats of SREHP was recognized by immune serum from a patient with amebiasis, demonstrating that SREHP is a naturally immunogenic protein. An antiserum raised against the recombinant fusion protein specifically bound to two distinct bands with apparent molecular masses of 46 and 52 kDa in a crude preparation of E. histolytica trophozoite membranes. This antiserum also inhibited E. histolytica trophozoite adhesion to Chinese hamster ovary cells in vitro. The ability to isolate E. histolytica-specific genes, and to express those genes in Escherichia coli, may be important in studying the molecular basis of E. histolytica pathogenesis and for the future development of vaccines.

Amino Acid Sequence↗
PubMed1990

Familial trends in palatal canines, anomalous lateral incisors, and related phenomena.

Our previous studies have established a strong link between small, peg-shaped and missing lateral incisors, and palatally-displaced maxillary canine teeth. Since these anomalies of lateral incisor development are known to be under strong genetic control, the hypothesis was that first degree relatives of patients with palatal canines would themselves show a raised prevalence of the anomalies. The present study also investigated a possible link between palatal canines and lateness in development of the dentition, and a relative absence of crowding, both of which are phenomena that have been mentioned both by us and elsewhere as similarly linked phenomena. Results showed that anomaly of the lateral incisors was found to be four times that of the general population and that positive links with late development of the dentition and a relative absence of crowding were also seen.

Adolescent↗
PubMed1990

Effects of beta-casomorphin derivatives on gastrointestinal transit in mice.

Some D-amino acid-substituted derivatives of beta-casomorphin (CM) were found to exhibit a special affinity to central opiate receptors. Concerning their affinity to peripheral opiate receptors our knowledge is still limited. The results of our experiments indicate that CM derivatives interfere with peripheral opiate receptors and that there is a close connection with the affinity to different subtypes of this receptor.

Amino Acid Sequence↗
PubMed1990

[Chorioretinitis in congenital toxoplasmosis].

The goal of this study was to establish the incidence of chorioretinitis in 100 infants whose mothers presented a seroconversion during the pregnancy. It is a retrospective study over 6.5 years. There were 17 cases of latent congenital toxoplasmosis (56.7%) and 13 cases of clinical congenital toxoplasmosis (43.3%). Three infants presented with chorioretinitis: one at birth in a context of general stroke, the two others at 2 and 17 months after birth, despite treatment. The risk of retinochorioditis was the same in the case of latent or clinical congenital toxoplasmosis. The fall in the antibody titre was not a good criterion of cure; the percentage of lymphocytes in the cerebrospinal fluid could constitute a better criterion. This study confirmed the efficacy of systemic treatment of congenital toxoplasmosis.

Antibodies, Protozoan↗