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Biomedical subjects

R Schmidt

Publications and source records attributed to R Schmidt.

At least 19 recordsLinked to original sources
PubMed1992

PFGE-resolved RFLP analysis and long range restriction mapping of the DNA of Arabidopsis thaliana using whole YAC clones as probes.

The cleavage patterns of 23 rare-cutting restriction endonucleases (rcREs) on high molecular weight DNA, isolated from leaves of Arabidopsis thaliana (Arabidopsis), have been analysed using pulsed field gel electrophoresis (PFGE). The DNA digested with rcREs can be used for restriction fragment length polymorphism (RFLP) analysis. We show that RFLPs are more readily identified in restriction fragments that require resolution by PFGE than in smaller restriction fragments. Taking advantage of the low dispersed repetitive DNA content of the Arabidopsis genome, whole yeast artificial chromosomes (YACs) were used as probes to PFGE resolved genomic DNA. This enabled whole YAC clones to be used as RFLP markers and long range restriction maps to be constructed. These techniques should enhance the analysis of regions of the genome of Arabidopsis (and other organisms with low levels of dispersed repetitive DNA) that are the subject of chromosome walking strategies to isolate particular loci.

Arabidopsis↗
PubMed1992

Mental and physical state in subclinical hyperthyroidism: investigations in a normal working population.

We investigated whether subclinically hyperthyroid individuals selected from a nonpatient working population exhibit similar impairments to those found in studies with patients. Sixteen subclinically hyperthyroid subjects without apparent reason (SH-0) and 15 subclinically hyperthyroid subjects on levothyroxine (SH-T4) were compared with 27 euthyroid controls with respect to signs and symptoms of hyperthyroidism, sleep, depressivity, ability to concentrate, anxiety, and other dimensions of well-being. We found that SH-T4 exhibited significantly higher TT4 levels, TT4/TBG ratios, and more palpitations than controls. Furthermore, they slept less. The SH-0 subjects reported being in a better mood and less touchy than controls. Psychometric results of all groups were within the normal range. A comparison of this study to previous studies reveals that TT4 levels or TT4/TBG ratios may play a crucial role in the development of the predominantly nervous symptoms in subclinical hyperthyroidism. Possible reasons for the discrepancies between results in hospital and nonhospital settings are discussed.

Adult↗
PubMed1992

Magnetic resonance imaging signal hyperintensities in the deep and subcortical white matter. A comparative study between stroke patients and normal volunteers.

Mixed population studies suggest a relationship between deep and subcortical white matter hyperintensities on magnetic resonance imaging and cerebrovascular disease. To further clarify this issue we compared the prevalence and extent of such signal abnormalities between a group of 133 consecutive stroke patients (mean age, 54.7 +/- 16.7 years) and 101 normal volunteers (mean age, 54.7 +/- 13.1 years). Diabetes and cardiac disease were significantly more common in patients than in normal subjects. Prevalence rates of clinically silent lesions were 44% and 47.5%, respectively. Beginning confluent and confluent foci were seen in 19.5% of patients, but in only 7.5% of normal subjects. Significant univariate correlations were found for the presence and extent of lesions with age, diabetes, cardiac disease, severity of extracranial carotid arteriosclerosis, and arterial hypertension, but not with the diagnosis of stroke or the type of brain infarction. Multivariate regression analysis established age and diabetes mellitus as the only independent predictors of white matter damage. We conclude that more extensive white matter abnormalities in stroke patients stem from their higher rate of cerebrovascular risk factors but are unrelated to the occurrence of ischemic attacks per se.

Adolescent↗
PubMed1992

Chilling sensitivity of Arabidopsis thaliana with genetically engineered membrane lipids.

Upon transfer of a genetically engineered Escherichia coli gene for glycerol-3-phosphate acyltransferase (plsB) to Arabidopsis thaliana (L.) Heynh., the gene is transcribed and translated into an enzymatically active polypeptide. This leads to an alteration in fatty acid composition of membrane lipids. From these alterations it is evident that the enzyme is located mainly inside the plastids. The amount of saturated fatty acids in plastidial membrane lipids increased. In particular, the fraction of high-temperature melting species of phosphatidylglycerol is elevated. These molecules are thought to play a crucial role in determining chilling sensitivity of plants. An increase in sensitivity could be observed in the transgenic plants during recultivation after chilling treatment. Implications for the hypothesis of phosphatidylglycerol-determined chilling sensitivity are discussed.

Arabidopsis↗
PubMed1992

Subclinical hyperthyroidism: physical and mental state of patients.

We investigated whether subclinical hyperthyroidism [subnormal basal thyroid-stimulating hormone (TSH) level, attenuated TSH response to thyrotropin-releasing hormone (TRH) stimulation, peripheral thyroid hormones within normal range] is accompanied by physical and mental changes. Thirty-five subclinically hyperthyroid patients (27 female, 8 male) were compared with 60 overtly hyperthyroid patients (51 female, 9 male) and with 28 euthyroid control patients (18 female, 10 male) with respect to physical symptoms, affective state, short-term memory, ability to concentrate and psychomotor performance. Patients with subclinical hyperthyroidism ranged between the other two groups. The major difference between controls and subclinically hyperthyroid patients was an increase in frequency of nervous symptoms and symptoms due to an increase of metabolic rate and thermal regulation changes. The major differences between subclinically hyperthyroid and overtly hyperthyroid patients were psychomotor impairment and symptoms of increased metabolic rate. Self-ratings of affective state tended to be similar in patients with subclinical and overt hyperthyroidism. The ability to concentrate and short-term memory were not impaired in any group. Symptoms in patients with subclinical hyperthyroidism probably result from central changes which lead to attenuated TSH responses to TRH, or from elevated but still normal thyroxine levels, which possibly enhance the effect of catecholamines.

Adult↗
PubMed1992

Malignant placental site trophoblastic tumor associated with placental abruption, fetal distress, and elevated CA-125.

The second pregnancy of 27-year-old woman, gravida 2, para 2 was complicated by a low alpha-fetoprotein and symptoms of chronic placental abruption. She delivered by cesarean section at 35 weeks for fetal distress at which time a biopsy of the uterus revealed a placental site trophoblastic tumor (PSTT). She rapidly developed intraabdominal spread of the neoplasm which did not respond to chemotherapy and she died 10 weeks later. Her CA-125 was elevated to 5360 mu/ml and this decreased after hysterectomy. This patient is reported to highlight a very malignant course of PSTT that was associated with a live-born male infant.

Abruptio Placentae↗
PubMed1992

Investigations of the acute toxic, cytogenetic, and embryotoxic activity of buminafos.

The organophosphorus herbicide buminafos (O,O-dibutyl-(1-butylaminocyclohexyl)-phosphonate) was tested for its acute toxic, cytogenetic, and embryotoxic activity on different strains of mice. The oral LD50 value for male NMRI mice was determined to be 3500 mg/kg. Single oral doses of 175, 1000, and 2000 mg/kg did not cause any significant enhancement in the percentage of chromosome aberrations in bone marrow cells of male NMRI mice. After oral administration of 500 and 1000 mg/kg buminafos to pregnant Halle:DBA and Halle:AB mice at Days 6-15 of gestation no embryotoxic effects were observed. The cytogenetic inactivity of buminafos in the bone marrow chromosome assay corresponds to negative findings in other mutagenicity tests.

Animals↗
PubMed1992

Neuronal plasticity depending on a glycoprotein synthesized in goldfish leptomeninx.

Transcription of a calcium and zinc binding, nervous system-specific cell adhesion glycoprotein, ependymin, in goldfish leptomeninx was significantly enhanced after active avoidance conditioning, followed by enhanced translation and secretion. Inactivation of secreted ependymin by injected antisera interfered with behavioral adaptations. In addition to the site of synthesis in reticular cells of the leptomeninx electronmicroscopic immunochemistry localized the protein to tectal neurons of the superficial plexiform and the periventricular cell layers. Detection of ependymin in cells where it is not synthesized, namely in neurons, suggests a re-uptake during functional activity of the CNS and assigns a pivotal role to the cerebrospinal and interstitial brain fluids for the distribution of protein factors that support axonal growth and neuronal plasticity.

Animals↗
PubMed1992

[Experimental studies on magnetic resonance tomographic and magnetic resonance angiographic imaging of poststenotic flow patterns].

A phantom has been developed, which permits the perfusion of defined stenosis with variable flow rates. The post-stenotic flow patterns were imaged by means of conventional MRI sequences and special angiographic sequences using a 1.5 total body scanner (Gyroscan S15, Philips). For conventional MRI images, spin-echo-sequences (TR 500 ms, TE 27 ms with reconstruction of the magnitude and phase images) and gradient-echo-sequences (TR 60 ms, TE 27 ms, flip angle 15 degrees with reconstruction of the magnitude images) were used. For MR angiography 2D inflow (multiple-single-slice-technique, TR 40 ms, TE 14 ms, flip angle 60 degrees) and flow-adjusted-gradient-sequences (TR 24 ms, TE 10 ms, flip angle 60 degrees) were performed. In addition to an analysis of the appearances, the length of the changed signal intensity beyond the stenosis was evaluated. For constant flow rates it increases with the severity of the stenosis. For a constant stenosis the length of the post-stenotic signal change alters with flow rate. The changes also depend on the direction of flow and the gradients of the chosen sequences. The comparison of magnitude and phase images allows the discrimination between turbulent and non-turbulent flow. It therefore appears possible to estimate the severity of arteriosclerotic occlusive disease by means of MRI in the future.

Blood Flow Velocity↗
PubMed1992

[Local 133xenon clearance in the eye and comparative in vitro wash-out time determination in patients with monoclonal gammopathy].

The authors investigated the dependence of the local clearance of 133xenon to the viscosity of the blood. Increase of viscosity of blood compared with decrease of local clearance of 133xenon by patients with monoclonal gammopathy were demonstrated. It was also shown that using the Beta-part of radiation of 133xenon is sufficient for looking for wash-out-times of the anterior eye segment. However, use of 133xenon in isotonic solution is also possible in other ophthalmological diseases for differentiation.

Animals↗
PubMed1992

Hepatic contrast-enhancing properties of manganese-mesoporphyrin and manganese-TPPS4. A comparative magnetic resonance imaging study in rats.

OBJECTIVES: Manganese (III) mesoporphyrin (Mn-mesoporphyrin), a synthetic and stable complex, was investigated for its hepatic magnetic resonance imaging (MRI) properties and compared with manganese tetrakis-(4 sulfonatophenyl) porphyrin (Mn-TPPS4). METHODS: Liver abscesses (n = 10) and tumors (n = 14) were induced in rats. These rats then underwent MRI at 2.0 T. Animals received one of the two contrast agents, and measurement of lesion enhancement was performed. RESULTS: At an intravenous dose of 0.035 mmol/kg, Mn-mesoporphyrin caused significant enhancement of normal liver parenchyma and increased the lesion-to-liver contrast in both the models of heptic liver abscess and metastatic liver disease. Mn-TTPS4 at an intravenous dose of 0.04 mmol/kg typically enhanced both lesion and normal liver parenchyma and therefore did not improve the lesion-to-liver contrast. CONCLUSIONS: The hepatotrophic properties of Mn-mesoporphyrin indicate its potential as an intravenous contrast agent for liver imaging.

Animals↗
PubMed1992

Tetrazolium [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] reduction by mycoplasmas.

We investigated 22 mycoplasma and acholeplasma species for their ability to reduce tetrazolium salts by using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. The test results were evaluated visually, as well as spectrophotometrically, by using an enzyme-linked immunosorbent assay reader. Our results were very similar to the results obtained when the tetrazolium salt reduction assay described by Aluotto et al. was used. However, the MTT reduction assay appeared to be better because it is faster, more objective and sensitive, easier to evaluate, and less expensive; in addition, it allows quantitative determinations. By using regression analysis a linear correlation between formazan production and the number of colony-forming units was demonstrated for all of the species investigated, indicating that the MTT assay can also be used for growth, toxicity, or chemosensitivity tests for the mycoplasma species that are capable of reducing tetrazolium salts.

Acholeplasma↗
PubMed1992

Differential expression of calgranulin A and B in various epithelial cell lines and reconstructed epidermis.

The monoclonal antibody F12, raised against epidermal cells from a psoriatic lesion, decorated antigens highly expressed in psoriatic epidermis and in cultured normal human keratinocytes. In normal human skin, F12 reacted only with follicular keratinocytes. Characterization of the immunoprecipitated antigens by two-dimensional gel electrophoresis revealed their identity with calgranulin A and B. A semiquantitative study with various established epithelial cell lines demonstrated that the expression of calgranulin A and B in hyperproliferative keratinocytes correlates with their potential to undergo terminal differentiation. In epidermis reconstructed in vitro, the antigen expression was stimulated by retinoids and suppressed under vitamin A starvation.

Antibodies, Monoclonal↗
PubMed1992

The prevalence of cerebral damage varies with migraine type: a MRI study.

Studies on the prevalence of MRI signal abnormalities in the brains of migraineurs have yielded controversial results. In order to provide further data on this issue we reviewed the MRI scans of 38 migraine patients without current neurologic symptoms (mean age 35.8 +/- 11.9 years). In addition, we compared the findings in those 24 migraineurs under 50 years without major cerebrovascular risk factors (mean age 30.1 +/- 9.0 years) to that in 14 headache and risk factor free volunteers (mean age 37.8 +/- 5.3 years). Overall, focal areas of hyperintense signal were seen in 15 (39%) patients. They were present on both proton density and T2-weighted spin-echo sequences. Lesion prevalence varied according to the type of headache (18% in migraine without aura, 53% in migraine with typical aura, 38% in basilar migraine). The subset of migraine patients under 50 years exhibited MRI signal abnormalities more than twice as often as controls (33% vs. 14%). Punctate white matter hyperintensities were the predominant finding and were seen in 10 of 15 individuals with MRI lesions. More striking signal abnormalities consisted of symmetrical areas of hyperintensity lateral to the posterior horns in two 24 year old patients and of extensive white matter damage with lacunar infarcts in a 59 year old woman. Our findings confirm a higher prevalence of MRI lesions in a mixed group of migraineurs than in headache free individuals. Signal abnormalities are most often non-specific, however their occurrence relates to the type of migraine.

Adolescent↗
PubMed1992

Comparison of magnetic resonance imaging in Alzheimer's disease, vascular dementia and normal aging.

MRI scans of 27 patients with probable Alzheimer's disease (mean age 68.2 years), 31 patients with vascular dementia (mean age 69.9 years) and 18 normal controls (mean age 66.3 years) were compared to evaluate possible distinguishing parenchymal abnormalities among these groups. Atrophy was quantitated by subjective rating, linear and volumetric measurements. A number of findings were significantly more common in vascular dementia than in the other subsets. These included (1) basal ganglionic/thalamic hyperintense foci, (2) thromboembolic infarctions, (3) confluent white matter and (4) irregular periventricular hyperintensities. Signal abnormalities on intermediate T2-weighted scans in the uncal-hippocampal or insular cortex were frequently and almost exclusively noted in Alzheimer's disease. Moderate and severe cortical and ventricular atrophy and a third ventricular to intracranial width ratio larger than 7% were good discriminators between demented groups and normally aging controls. Selective atrophy measurements, however, failed to separate dementia syndromes. These results suggest that MRI has the potential to increase the accuracy of the clinical diagnosis of Alzheimer's disease and vascular dementia.

Aged↗