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Biomedical subjects

A Koch

Publications and source records attributed to A Koch.

At least 253 records · Page 14Linked to original sources
PubMed1991

Experimental investigations on the influence of anemia on gentamicin ototoxicity.

The purpose of this study was to determine whether or not anemic patients have a higher risk of gentamicin ototoxicity. Using the laboratory rat as an animal model with auditory brain-stem response measurements and surface preparations of the organ of Corti, it could be shown that cochlear damage in anemic rats treated with gentamicin was significantly higher (P less than 0.05) than in the nonanemic ones treated with the same dosages of antibiotic. Doses of gentamicin used were 50 mg/kg for 30 days and 40 mg/kg for another 75 days.

Anemia↗
PubMed1991

Differentiation of species and strains among filamentous fungi by DNA fingerprinting.

We have analyzed 11 strains and clones, representing five species (Penicillium janthinellum, P. citrioviridae, P. chrysogenum, Aspergillus niger, Trichoderma harzianum) and three genera of filamentous fungi, for the presence of hypervariable loci in their genomes by hybridization with simple repeat oligonucleotides and the DNA of phage M13. The oligonucleotide probes (CT)8, (GTG)5 and (GACA)4, as well as M13 DNA, are informative probes for fingerprinting in all genera and species tested. The probe (GATA)4 produced informative fingerprints only with the genomic DNA of A. niger. There was no similarity between the fingerprints originating from fungi of different genera and also little similarity between the fingerprints of different species belonging to the same genus. Fingerprints of strains of the same species differed only slightly from each other. Fingerprints of clones originating from one strain were identical. The results indicate that DNA fingerprinting is a powerful method to differentiate species and strains of filamentous fungi.

Aspergillus niger↗
PubMed1991

[Otoplasty. Results and complications with a modified Mustardé's technique].

In order to investigate the results obtained after surgical treatment of prominent ears with a modified method basically derived from the technique of Mustardé 340 patients had been interrogated and 150 had been examined postoperatively. In 91.4% of the cases the patients themselves and in 84.7% the surgeon was satisfied by the postoperative result. Recurrence was observed in 17% and was due partly to the intermittent use of a resorbable suture material. In some cases recurrence consisted in a slight asymmetry, that was not really disturbing and did not need a further correction. A fundamental advantage of our surgical method is the fact that the cartilage has not to be destroyed, so that ugly and unnatural rims are avoided as well as some further postoperative complications (otohematoma, perichondritis, pain and sensibility to the cold). Revision surgery even by another technique is always possible because the cartilage is left intact.

Adolescent↗
PubMed1991

[Operative correction of dysgnathism as preprosthetic management].

The prosthetic management of edentulous patients with skeletal dysgnatism is difficult. Surgical treatment as Le-Fort-I-osteotomy or sagittal split and rigid fixation with plates can be helpful. Technique, indications and additional procedures are introduced in two clinical cases.

Adult↗
PubMed1991

[Otoplasty: results of a modified form of Mustardé's method].

In order to investigate the results obtained after surgical treatment of prominent ears with a modified method basically derived from the technique of Mustardé 340 patients had been interrogated and 150 had been examined postoperatively. In 91.4% of the cases the patients themselves and in 84.7% the surgeon was satisfied by the postoperative result. Recurrence was observed in 17% and was due partly to the intermittent use of a resorbable suture material. In some cases recurrence consisted in a slight asymmetry, that was not really disturbing and did not need a further correction. A fundamental advantage of our surgical method is the fact that the cartilage has not to be destroyed, so that ugly and unnatural rims are avoided as well as some further postoperative complications (othematoma, perichondritis, pain and sensibility to the cold). Revision surgery even by another technique is always possible because the cartilage is left intact.

Ear, External↗
PubMed1991

Polyclonal B-cell stimulation by T-cells in a parasitic disease.

Polyclonal B-cell stimulation resulting in B-cell proliferation and antibody production occurs in many infectious diseases. Here, we review our data showing that CD4-positive T-cells are instrumental for such polyclonal B-cell stimulation in a chronic parasitic infection, namely murine cutaneous leishmaniasis. The mechanism used by the T-cells involves a membrane interaction between B-cells and activated T-cells which can take place in the absence of antigen, as well as the action of lymphokines such as IL-4. The membrane interaction does not seem to involve the CD4 molecule on T-cells and MHC class II molecules on B-cells, as it is the case in cognate interaction during antigen-specific stimulation of B-cells by CD4 positive T-helper cells. Whether or not adhesion molecules, e.g. of the integrin family, play a role in the triggering process, is currently under investigation.

Animals↗
PubMed1990

The value and cost-effectiveness of a home-visiting programme for psychiatric patients.

The high rate of readmissions to psychiatric hospitals constitutes a considerable problem. An attempt to reduce these by a controlled standard home-visiting procedure was carried out for 51 consecutive patients at Valkenberg Hospital, Cape Town. Readmissions were reduced by 31.5% over 1 year and the number of days in hospital by 55.6% from 3714 to 1850 days. Attendance at outpatient clinics also improved by 39%. The cost-effectiveness of this programme was also demonstrated; there was a saving of approximately R786 per patient over the year.

Adult↗
PubMed1990

The tyrosine phosphorylated carboxyterminus of the EGF receptor is a binding site for GAP and PLC-gamma.

Phospholipase C-gamma (PLC-gamma) and GTPase activating protein (GAP) are substrates of EGF, PDGF and other growth factor receptors. Since either PLC-gamma or GAP also bind to the activated receptors it was suggested that their SH2 domains are mediating this association. We attempted to delineate the specific region of the EGF receptor that is responsible for the binding, utilizing EGF receptor mutants, PLC-gamma, and a bacterially expressed TRP E fusion protein containing the SH2 domains of GAP. As previously shown, tyrosine autophosphorylation of the wild-type receptor wsa crucial in mediating the association and in agreement, a kinase negative EGF receptor could bind PLC-gamma or TRP E GAP SH2, but only when cross tyrosine phosphorylated by an active EGF receptor kinase. The importance of autophosphorylation for association was confirmed by demonstrating that a carboxy-terminal deletion of the EGFR missing four autophosphorylation sites bound these proteins poorly. To study the role of EGF receptor autophosphorylation further, a 203 amino acid EGF receptor fragment was generated with cyanogen bromide that contained all known tyrosine autophosphorylation sites. This fragment bound both TRP E GAP SH2 and PLC-gamma but only when tyrosine phosphorylated. This data localizes a major binding site for SH2 domain containing proteins to the carboxy-terminus of the EGF receptor and points to the importance of tyrosine phosphorylation in mediating this association.

Animals↗
PubMed1990

Possible role of acetaldehyde in ethanol-related rectal cocarcinogenesis in the rat.

Prospective epidemiologic studies have reported an increased risk of rectal cancer following chronic ethanol ingestion. The effect of ethanol on chemically induced colorectal carcinogenesis is controversial depending on the experimental conditions. In the present study the effect of chronic ethanol administration on acetoxymethylmethylnitrosamine-induced rectal cancer and the possible role of acetaldehyde in this process were investigated. Chronic ethanol administration resulted in an earlier occurrence of rectal tumors in this animal model. Because the concomitant administration of cyanamide, a potent acetaldehyde dehydrogenase inhibitor, showed a positive trend toward increased incidences of tumors, acetaldehyde could be involved in the ethanol-associated carcinogenesis. To measure colonic acetaldehyde, 12 chronically ethanol-fed and control rats received an acute dose of ethanol (2.5 g/kg body wt). The mucosal concentration of acetaldehyde was significantly higher in the rectum compared with the cecum (198 +/- 23 vs. 120 +/- 23 nmoles.g colon-1, p less than 0.05), but was not affected by chronic ethanol feeding. Furthermore, 6 germ-free rats had significantly lower acetaldehyde concentrations in the rectum (84 +/- 11 vs. 234 +/- 33 nmoles.g colon-1, p less than 0.01) and in the cecum (59 +/- 13 vs. 121 +/- 33 nmoles.g colon-1, p less than 0.05) compared with 6 conventional animals, and this was paralleled by the number of fecal bacteria in the 2 intestinal segments. In addition, to determine the effect of chronic ethanol feeding on colorectal cell turnover, 30 animals were pair-fed liquid diets. Using the metaphase-arrest technique, alcohol feeding induced rectal (19.1 +/- 2.0 vs. 9.1 +/- 1.8 cells.crypt-1.h-1, p less than 0.01), but not cecal (18.9 +/- 1.3 vs. 22.2 +/- 3.3 cells.crypt-1.h-1, p greater than 0.05) hyperregeneration. This was accompanied by an increase in the crypt proliferative compartment and increased mucosal ornithine decarboxylase activity (63 +/- 18 vs. 22 +/- 6 pmoles.hr-1.mg protein-1, p less than 0.05). The data show that chronic ethanol ingestion accelerates chemically induced rectal carcinogenesis and raise the possibility that acetaldehyde probably generated through bacterial ethanol oxidation may be involved in this process. The secondary hyperregeneration of the mucosa, observed after alcohol feeding, could by itself favour carcinogenesis.

Acetaldehyde↗
PubMed1990

Differentiation between negative inotropic drugs by means of potentiated post-rest contractions in guinea-pig heart.

1. It was tested using isolated guinea-pig atria whether negative inotropic drugs could be differentiated by measuring force under both equilibrium conditions and after a rest period leading to potentiated beats. 2. A drug believed to interfere with sarcoplasmic reticular function, ryanodine, preferentially suppressed potentiated beats, whereas the calcium antagonists gallopamil and felodipine selectively depressed force under continuous stimulation. 3. Gentamicin and doxorubicin also exerted characteristic effects on the two force parameters, the former resembling calcium antagonists, the latter ryanodine. 4. The method used is suitable for a descriptive classification of negative inotropic drugs, possibly according to their cellular mode of action.

Animals↗
PubMed1990

The effect of research on readmission to a psychiatric hospital.

The effects on outcome of research into the course of psychiatric illness are controversial. This study examines a cohort of research patients involved in an outcome study in which the research and clinical teams were kept separate. While research intervention of this nature would not be expected to influence outcome, the research cohort had fewer readmissions than non-research controls. This occurred despite the presence of factors which would be expected to be associated with a contrary result. It is stressed that the confounding effects of research need to be taken into account when designing follow-up studies and evaluating outcome results.

Adult↗
PubMed1989

Improving compliance in Xhosa psychiatric patients.

Compliance with psychotropic medication is particularly poor in Xhosa psychiatric patients. A study demonstrated that explicit and repeated verbal and written instructions did not increase compliance with oral medication, but that a single home visit, limited to giving instructions about medication, almost doubled the compliance rate (to 65%). Similar increases also occurred in relation to intramuscular medication and clinic attendance. The most common reason for noncompliance was found to be resistance to, or plain ignoring of, what was actually known (64%). Several possible reasons for this are proposed, the most significant being the patients' cultural and social attitudes and belief system. Recommendations for increasing compliance are given.

Black or African American↗