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Biomedical subjects

J Schmidt

Publications and source records attributed to J Schmidt.

At least 577 records · Page 32Linked to original sources
PubMed1989

Positive and negative control of nod gene expression in Rhizobium meliloti is required for optimal nodulation.

We show that expression of common nodulation genes in Rhizobium meliloti is under positive as well as negative control. A repressor protein was found to be involved in the negative control of nod gene expression. Whereas the activator NodD protein binds to the conserved cis-regulatory element (nod-box) required for coordinated regulation of nod genes, the repressor binds to the overlapping nodD1 and nodA promoters, at the RNA polymerase binding site. A model depicting the possible interaction of the plant-derived nod gene inducer (luteolin), the NodD and the repressor with the nod promoter elements is presented. Mutants lacking the repressor exhibited delayed nodulation phenotype, indicating that fine tuning of nod gene expression is required for optimal nodulation of the plant host.

Journal Article↗
PubMed1989

Biochemical characterization of a virus-induced osteosarcoma-like osseous lesion in vitro.

Chondroprogenitor cells present in the apical and lateral parts of the mandibular condyle from neonatal mice differentiate towards the osteoblastic lineage and form bone within 7 days in culture. Infection of condylar explants with the FBR osteosarcoma virus (FBR MSV) results in the transformation of cells in the progenitor zone, previously identified as the target for the virus, and the formation of a transplantable osteosarcoma-like lesion. Morphological and biochemical changes in this system were investigated in the course of tumor development. Virus infection was followed by a significant increase in cell density and 3H-thymidine incorporation within the progenitor zone at the early stage of culture. In later stages, cell density and 3H-thymidine incorporation were lower than in control tissue. The 3H-thymidine labeling index gave similar results in infected and control tissues until day 7. Then, a significantly higher labeling index was found in the progenitor zone of infected condyles. At this stage, the proliferative effect of the virus even affected the cartilagenous core of the tissue. Quantitative alkaline phosphatase activity increased between day 3 and day 7 and was particularly high in the zone of infected cells. In addition, infected tissues consistently revealed a higher uptake of 45Ca, and deposition of the radioisotope along irregularly formed bone trabecules in the transformed tissue. The results suggest that there is an enhancement of tissue maturation following infection with the FBR osteosarcoma virus. Although biochemical investigations of whole condyles showed few differences in the total values of alkaline phosphatase activity, 3H-thymidine incorporation, DNA content, and 45Ca uptake, the histochemical assays revealed clear differences in the distributional pattern of these parameters within infected and control condyles.

Alkaline Phosphatase↗
PubMed1989

Effects of leukemogenic retroviruses on condylar cartilage in vitro: an ultrastructural study.

Mandibular condyles of late embryonic NMRI mice were used in an in vitro organ culture system to study the effect of bone tumor-derived murine leukemia viruses OS-5 MuLV and OA MuLV known to induce osteopetrosis and osteomas. Skeletal precursor cells present in the condylar tissue normally undergo rapid differentiation in vitro which results in new bone formation. The infection of condyles with either OS-5 MuLV or OA MuLV markedly interfered with the normal developmental pattern of the organ leading to the formation of an atypical, heavily mineralized tissue. Many spindlelike cells and pleomorphic cells were encountered, whereas fibroblastlike cells were found to penetrate an underlying collagen substratum. These observations indicate that bone tumor-inducing leukemogenic retroviruses directly affect cartilage and/or bone precursor cells resulting in pathologic developments in the skeleton.

Animals↗
PubMed1989

Comparative studies on the protein composition of hymenopteran venom reservoirs.

The proteins of venom reservoirs from 25 hymenopteran species from 21 genera were investigated with regard to their protein composition and immunological similarities. It was found that low mol. wt proteins and polypeptides are typical for the venoms of ants, social wasps and bees. Six species of ichneumonoid parasitic wasps lack these low mol. wt proteins. Except for bee venoms none of the low mol. wt proteins contain mannose. The venoms of ichneumonoid parasites and ants contained primarily acidic proteins, whereas those of social wasps and bees contained abundant neutral and basic proteins. Immunological analysis showed that a number of venom proteins from parasitic braconid (Chelonus) wasps shared conserved immunoreactive determinants with the venom proteins of higher Hymenoptera, including some not of parasitic habit. Implications of phylogenetic relationships among hymenopteran species are discussed.

Animals↗
PubMed1989

Increased brain water content in pseudotumour cerebri measured by magnetic resonance imaging of brain water self diffusion.

Brain water self diffusion was investigated by magnetic resonance scanning in 7 patients fulfilling conventional diagnostic criteria for pseudotumour cerebri. Quantitative diffusion measurements were obtained using single spin echo pulse sequences with pulsed magnetic field gradients of different magnitude. In all patients the diffusion images showed an increased diffusion in various brain regions when compared with the diffusion coefficients for corresponding regions in healthy subjects. In 3 pseudotumour patients the increased self diffusion was localized to the periventricular regions, while 4 patients had increased diffusion in the whole brain. The findings indicate the presence of increased brain water content both intra- and extracellularly suggesting that patients with pseudotumour have two defects of pathogenetical significance: intracellular water accumulation and increased resistance to cerebrospinal fluid (CSF) outflow leading to an interstitial oedema.

Adult↗
PubMed1989

Skeletal muscle denervation activates acetylcholine receptor genes.

Transcriptional activity of acetylcholine receptor subunit genes was investigated in innervated and denervated chick skeletal muscle. The sciatic nerve of 3-d-old White Leghorn chicks was sectioned unilaterally; after various intervals, nuclei were isolated from operated and sham-operated animals, and run-on assays performed. Nuclei were incubated with 32P-UTP, and total RNA was extracted and hybridized onto filters containing an excess of subunit-specific DNA. Specific transcripts were detected by autoradiography and quantitated densitometrically. A sharp increase in transcriptional activity was observed to begin approximately 1/2 d after the operation and peak 1 d later when transcriptional rates reached approximately seven-, six-, and fivefold control levels for the alpha-, delta-, and gamma-subunit genes, respectively. The specificity of the effect was ascertained by normalization to total RNA synthesis and by the demonstration that several nonreceptor genes respond differently to denervation. These results suggest that a denervation signal reaches the genome to induce receptor expression. In addition, since the increase in mRNA levels significantly exceeds what can be accounted for by increased gene activity, posttranscriptional effects are suggested.

Animals↗
PubMed1989

Immunohistochemical demonstration of immunoglobulin A in human sebaceous and sweat glands.

Immunoglobulin A (IgA) mediated humoral defense mechanisms have been detected on all mucous membrane surfaces. There are only a few papers about the presence of IgA in human skin. In order to demonstrate the occurrence of IgA in sebaceous and sweat glands, biopsies of normal human skin were investigated and compared to intestinal mucosa. Two different commercially available anti-IgA antibodies were used. For light microscopy peroxidase-anti-peroxidase (PAP) or avidin-biotin complex (ABC) staining was used, and for electron microscopy protein-A-gold (PAG) labeling was performed on tissue sections. Specifically decorated IgA was found in sebaceous glands as well as in various portions of eccrine glands. In sebaceous glands, the maximum of IgA concentration was seen near the mouth of pilosebaceous ducts. Sweat ducts exhibited a continuous coat of IgA, whereas secretory portions contained only singular scattered IgA positive cells. Immunoelectron microscopy suggests endocytotic uptake and processing of IgA in the glandular cells. These results indicate strongly that IgA are secreted by normal human sebaceous and sweat glands. Because it is well known that IgA plays an important role in inactivation of invading viruses, bacteria, and other antigenic structures on mucous membranes, it appears that IgA in sebum and sweat fulfil a similar function on the outer body surface.

Adolescent↗
PubMed1989

[The spectrum of bacterial strains and problems of antibiotic prophylaxis in an intensive care unit].

Out of a total number of 1,935 patients of a mainly cardiac surgically orientated intensive care unit, 103 material extractions and 111 germ diagnoses with resistance examinations were carried out in 60 patients. The infection rate was 3.1%. Thirty-two of the 60 patients died (53.3%). Fifty-seven patients (95%) underwent open-heart surgery. With respect to the total number of open-heart operations (n = 1,345), the rate of severe infections was 4.23%. The germ spectrum reveals a predominance of "problem germs", especially pseudomonas and enterobacteria. The results of the resistance examinations show that no antibiotic combination is suitable for complete germ elimination. Cefotiam (halospor) is effective against 50% of the germs. Problems of an antibiotic prophylaxis are shown. Recommendations are given to restrict antibiotic prophylaxis to 24 hours perioperatively, preferably using a cephalosporin preparation.

Anti-Bacterial Agents↗
PubMed1989

[The role of gastrectomy in the treatment of hemorrhaging stomach ulcers].

It is reported about 6 patients whose bleeding gastric ulcers required gastrectomy as ultima ratio. The operative technique depends on the individual case. Gastrectomy is indicated in patients with diffuse bleeding from erosions or multiple ulcers especially combined to coagulation disorders or in patients with recurrence bleeding after previous gastric resection. We saw no letal complication in spite of unfavourable initial conditions and major operating trauma. There were no essential postoperative complications except of one patient. The definite hemostasis seems to be most important for the prognosis of such critically ill patients.

Aged↗
PubMed1989

The antihypoxic effect of ethymisole: a comparison with other nootropic drugs.

Ethymisole reveals a potent antihypoxic effect which is produced probably both by an acute free radical scavenging property and a persisting restitutive component of action. This is seen in its effect on posthypoxic inhibition of dopamine release from striatum slices of adult rats. Though ethymisole is considered a drug which increases brain adaptive potency, it does not modify the stimulus-response relation of potassium-evoked dopamine release in an adaptation-like manner, as it is seen after a long-lasting piracetam treatment.

Animals↗
PubMed1989

Colonization of pregnant women and their newborn infants with group B streptococci in the Gondar College of Medical Sciences.

In a study of Group B streptococcal carriage, 200 postpartum women and 80 newborn infants were investigated in the Gondar College of Medical Sciences from January to April 1987, using swabs from the vagina and rectum, and from the throat and external ear, respectively. We found a colonization rate of 9% (18/200) in the mothers and 5% (4/80) in the neonates. The serological typing of the 25 isolated strains showed 60% (15/25) to be Type Ib/c and 16% (4/25) to be Type Ia strains. Therefore, in newborn infants with infections, diagnostic and bacteriological procedures should include a search for Group B Streptococci.

Carrier State↗
PubMed1989

A sensitive method for the determination of the mitochondrial susceptibility factor (MSF).

A sensitive method for the determination of the activity of MSF in the cytosol of reticulocytes is described. It is based on the fact that proteolysis products from the mitochondria containing stroma of immature reticulocytes (fraction I) are only liberated if MSF is added. The reproducibility of the method is documented with partly purified MSF. A drawback is the limited range of MSF which can be tested.

Animals↗
PubMed1989

Influence of hypoxia on the age dependent stimulus-effect-relation of K+-induced dopamine release from rat brain structures.

There is a well defined correlation between stimulus intensity (potassium concentration) and the so-called fractional efflux rate of radio-labelled neurotransmitter from loaded brain structures. K+-induced dopamine release shows an age-dependent parallel shift of the stimulus-effect-relation which obviously reflects quantitative developmental changes during maturation (increasing release) and involution (restricted release) of neuronal structures and functions without modification of involved mechanisms in a qualitative manner. On the other side, mild hypoxia results in quite different, even opposite changes of the stimulus-effect-relation exhibiting the most diverse vulnerability and reactivity of neuronal stimulus-release-coupling at different age.

Aging↗
PubMed1989

New aspects in mechanisms of antihypoxic piracetam action.

A long-term piracetam treatment leads to an improved stimulus-effect-coupling of potassium stimulated dopamine release: The maximum effect of the potassium stimulus is already obtained in presence of much lower Ca++-concentrations (Ca++-economizing effect) than normally. In consequence of the improved stimulus-effect-coupling by piracetam treatment the dose-dependent inhibitory effect of the calcium antagonist flunarizine on the fractional efflux rate of dopamine is decreased. The volume of vesicular structures is not involved in the piracetam effect.

Animals↗
PubMed1989

[Satisfaction with inpatient management. Development of a questionnaire and initial validity studies].

In Germany methodologically reliable procedures to assess patients satisfaction with inpatient health care are almost totally missing. With reference to the well known American CSQ-Questionnaire (Attkisson et al.) a 17-items questionnaire (to assess satisfaction) was developed and presented to a sample of 300 patients undergoing inpatient treatment within a psychosomatic clinic (the rate of responding was about 80%). With a concise form of the questionnaire (Zuf-8, 8 items) an economical and reliable test-instrument is presented in this paper to measure general satisfaction, which also was investigated in regard to item- and factor analysis. This method seems suitable for measuring patient satisfaction with inpatient psychosomatic treatment. The investigated scales of satisfaction show a statistically significant correlation with additionally obtained patient characteristics. This inquiry also suggests that it might be rewarding to pursue the often neglected phenomenon of questionnaires filled out incomplete as an indicator of latent dissatisfaction.

Adult↗