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Biomedical subjects

R Schmidt

Publications and source records attributed to R Schmidt.

At least 271 records · Page 15Linked to original sources
PubMed1997

The mutation masculinizer (man) defines a sex-determining gene with maternal and zygotic functions in Musca domestica L.

In Musca domestica, the primary signal for sex determination is the dominant factor M, which is assumed to regulate a postulated female-determining gene F. Presence of M prevents expression of F so that male development ensues. In the absence of M, F can become active, which dictates the female pathway. The existence of F is inferred from FD. a dominant factor that is epistatic to M. We describe a new mutation masculinizer, which has all the properties expected for a null or strongly hypomorphic allele of F: (1) it maps to the same chromosomal location as FD, (2) homozygous man/man animals develop as males, (3) homozygous man/man clones generated in man/+ female larvae differentiate male structures, (4) man has a sex-determining maternal effect. About a third of the morphological males synthesize yolk proteins, which indicates that they are intersexual in internal structures. The maternal effect of man is complete in offspring that derive from homozygous man/man pole cells transplanted into female hosts. In this case, all man/+ progeny become fertile males that do not produce yolk proteins A sex-determining maternal effect has previously been demonstrated for FD. Like F, maternal man' is needed for zygotic man' to become active, providing further evidence that man is a loss-of-function allele of F.

Animals↗
PubMed1997

The Y-chromosomal and autosomal male-determining M factors of Musca domestica are equivalent.

In Musca domestica, male sex is determined by a dominant factor, M, located either on the Y, the X or on an autosome. M prevents the activity of the female-determining gene F. In the absence of M, F becomes active and dictates female development. The various M factors may represent translocated copies of an ancestral Y-chromosomal M. Double mutants and germ line chimeras show that MY, MI, MII, MIII and MV perform equivalent functions. When brought into the female germ line, they predetermine male development of the offspring. This maternal effect is overruled by the dominant female-determining factor FD. MI and MII are weak M factors, as demonstrated by the presence of yolk proteins in MI/+ males and by the occurrence of some intersexes among the offspring that developed from transplanted MI/+ and MII/+ pole cells. The arrhenogenic mutation Ag has its focus in the female germ line and its temperature-sensitive period during oogenesis. We propose that MI and Ag represent allelic M factors that are affected in their expression. Analysis of mosaic gonads showed that in M. domestica the sex of the germ line is determined by inductive signals from the surrounding soma. We present a model to account for the observed phenomena.

Animals↗
PubMed1997

The impact of sociodemographic, environmental, and behavioral factors, and cerebrovascular risk factors as potential predictors of the mattis dementia rating scale.

BACKGROUND: Age and education have been found to affect the Mattis Dementia Rating Scale (MDRS) score of elderly normals, but there have been no studies assessing the influence of environmental and behavioral factors on this scale. Their role as potential predictors of the MDRS total score was investigated. METHODS: The MDRS was administered to 1,927 normal elderly subjects in the setting of a stroke prevention study. Results were correlated with 16 sociodemographic, environmental, and behavioral factors, and cerebrovascular risk factors. Study statistics resulted from multiple logistic regression analysis. RESULTS: Results indicated that higher age and arterial hypertension were associated with poorer cognitive performance, while better education and moderate general life stress exerted a positive effect on the participants' test results. CONCLUSIONS: Thus, besides the well-established factors of age and educational level, moderate general life stress and hypertension were identified as relevant predictors in determining the MDRS test performance of elderly normals.

Aged↗
PubMed1997

A randomized, double-blind, dose-response comparison of epidural fentanyl versus sufentanil analgesia after cesarean section.

This study was designed to determine and compare the dose-response characteristics, speed of onset, and relative potency of single-dose epidural fentanyl (F) and sufentanil (S) for postoperative pain relief. Eighty women undergoing cesarean section (C/S) with epidural 2% lidocaine with epinephrine (1:200,000) were randomly assigned to receive double-blind epidural administration of F (25, 50, 100, or 200 microg) or S (5, 10, 20, or 30 microg) (n = 10 per group) upon complaint of pain postoperatively. Visual analog scales (VAS, 0-100 mm) were used to assess pain and sedation at baseline; at 3, 6, 9, 12, 15, 20, 25, 30, 45, and 60 min; and every 30 min until further analgesia was requested. The study was terminated at 30 min if satisfactory analgesia was not achieved. Side effects were recorded. A dose-response was demonstrated for both opioids. F 25 microg and S 5 microg were ineffective, with significantly fewer women achieving VAS scores <10 mm (P < 0.05 compared with F 100 or 200 microg and S 20 or 30 microg). F 100 and 200 microg and S 20 and 30 microg all achieved VAS scores <10 mm in all women with no differences in time to 50% reduction in VAS (mean 11-16 min) and no differences in duration of analgesia (mean 117-138 min). The 50% and 95% effective dose values for each opioid to achieve a VAS score <10 mm were F 33 microg and 92 microg and S 6.7 microg and 17.5 microg. There were no differences among groups in sedation scores or side effects. Our data suggest that the relative analgesic potency of epidural S:F is approximately 5 and that there are no differences between the opioids in the onset, duration, and effectiveness of analgesia when equianalgesic doses are administered postoperatively after lidocaine anesthesia for C/S.

Adult↗
PubMed1997

Expression of the RET/PTC fusion gene as a marker for papillary carcinoma in Hashimoto's thyroiditis.

Hashimoto's thyroiditis is an inflammatory disease of the thyroid gland with autoimmune etiology. Patients afflicted with Hashimoto's have a higher risk of thyroid malignancies such as papillary thyroid carcinoma. In the present study, we investigated the frequency of papillary thyroid carcinoma specific genes in patients diagnosed with Hashimoto's disease. The newly identified oncogenes RET/PTC1 and RET/PTC3 provide useful and specific markers of the early stages of papillary carcinoma as they are highly specific for malignant cells. Using a sensitive and specific reverse transcriptase-polymerase chain reaction (RT-PCR) assay, we found messenger RNA (mRNA) expression for the RET/PTC1 and RET/PTC3 oncogenes in 95% of the Hashimoto's patients studied. All Hashimoto's patients presenting without histopathologic evidence of papillary thyroid cancer showed molecular genetic evidence of cancer. These data suggest that multiple, independent occult tumors exist in these patients at high frequency.

Adult↗
PubMed1997

Mycoplasma crocodyli sp. nov., a new species from crocodiles.

Organisms with the typical characteristics of mycoplasmas were isolated from joints and lungs of crocodiles. The results of growth inhibition tests and immunobinding assays showed that the 24 mycoplasma strains isolated were identical and distinct from previously described Mycoplasma, Entomoplasma, Mesoplasma, and Acholeplasma species. These organisms represent a new species, for which the name Mycoplasma crocodyli is proposed. M. crocodyli ferments glucose and maltose, does not produce films and spots, does not hydrolyze arginine, esculin, and urea, reduces tetrazolium chloride, and possesses phosphatase activity. It lyses and adsorbs bovine, ovine, and rabbit erythrocytes. Cholesterol or serum is required for growth. The optimum growth temperature is 37 degrees C. The G + C content of the DNA is 27.6 mol%. This organism causes exudative polyarthritis in crocodiles. The type strain of M. crocodyli is strain MP145 (= ATCC 51981).

Alligators and Crocodiles↗
PubMed1997

Mycoplasma lagogenitalium sp. nov., from the preputial smegma of Afghan pikas (Ochotona rufescens rufescens).

Organisms with characteristics typical of mycoplasmas were isolated from the preputial smegma of Afghan picas (Ochotona rufescens rufescens). The results of growth inhibition tests, metabolic inhibition tests, and immunobinding assays showed that the isolated strains were identical and that they were distinct from previously described Mycoplasma, Entomoplasma, Mesoplasma, and Acholeplasma species. These organisms represent a new species, for which the name Mycoplasma lagogenitalium is proposed. M. lagogenitalium ferments glucose, does not hydrolyze arginine or urea, reduces tetrazolium chloride, possesses phosphatase activity, does not digest gelatin or casein, and does not produce films or spots. It lyses sheep erythrocytes and does not adsorb sheep, rabbit, or horse erythrocytes. Cholesterol or serum is required for growth. The growth temperature is 37 degrees C. The guanine-plus-cytosine content of the DNA is 23.0 +/- 1.0 mol%. The type strain is M. lagogenitalium 12MS (= ATCC 700289T).

Animals↗
PubMed1997

The Arabidopsis downy mildew resistance gene RPP5 shares similarity to the toll and interleukin-1 receptors with N and L6.

Plant disease resistance genes operate at the earliest steps of pathogen perception. The Arabidopsis RPP5 gene specifying resistance to the downy mildew pathogen Peronospora parasitica was positionally cloned. It encodes a protein that possesses a putative nucleotide binding site and leucine-rich repeats, and its product exhibits striking structural similarity to the plant resistance gene products N and L6. Like N and L6, the RPP5 N-terminal domain resembles the cytoplasmic domains of the Drosophila Toll and mammalian interleukin-1 transmembrane receptors. In contrast to N and L6, which produce predicted truncated products by alternative splicing, RPP5 appears to express only a single transcript corresponding to the full-length protein. However, a truncated form structurally similar to those of N and L6 is encoded by one or more other members of the RPP5 gene family that are tightly clustered on chromosome 4. The organization of repeated units within the leucine-rich repeats encoded by the wild-type RPP5 gene and an RPP5 mutant allele provides molecular evidence for the heightened capacity of this domain to evolve novel configurations and potentially new disease resistance specificities.

Alleles↗
PubMed1997

Integration of Langerhans cells into a pigmented reconstructed human epidermis.

The majority of in vitro reconstructed human epidermis is composed of keratinocytes only. Recently, the introduction of melanocytes into epidermal reconstructs has enlarged their field of application. The completion of reconstructed epidermis by introducing Langerhans cells remained an important challenge because Langerhans cells, unlike the other epidermal cell types, cannot be subcultured and expanded. To solve this problem, we used cord blood-derived CD34+ hematopoietic progenitors. Seeding these cells, after induction of their differentiation by granulocyte macrophage-colony stimulating factor and tumor necrosis factor-alpha, onto a reconstructing epidermis, composed of keratinocytes and melanocytes, gives rise to a pigmented epidermis with melanocytes in the basal layer and resident epidermal Langerhans cells located suprabasally. Interestingly, the same result was obtained by co-seeding a mixture of keratinocytes, melanocytes, and nondifferentiated CD34+ hematopoietic progenitors on the dermal equivalent, indicating that keratinocytes provide the environmental conditions for hematopoietic progenitors to differentiate into resident epidermal Langerhans cells, expressing major histocompatibility complex class II molecules, CD1a antigen, and Birbeck granules.

Antigens, CD34↗
PubMed1997

Stationary-phase mutants of Sinorhizobium meliloti are impaired in stationary-phase survival or in recovery to logarithmic growth.

A screening method was used to identify Sinorhizobium meliloti mutants which are affected in stationary-phase survival. Of 20,000 individual colonies mutagenized with transposon Tn5-B20, 10 mutant strains which showed poor or no survival in the stationary phase were identified. Analyses of expression patterns of the promoterless lacZ genes in the mutant strains revealed individual induction patterns. Most strains were induced in stationary phase as well as under carbon limitation and in pure H2O, but none of the mutants was induced under heat, alkali stress conditions, or low oxygen tension. Plant inoculation tests revealed that the symbiotic proficiency of the mutants was not affected. Two mutants, however, showed gene induction not only in the stationary phase under free-living conditions but also in the bacteroid state. A long-term starvation test was carried out to examine the ability of the 10 mutants to survive prolonged stationary-phase conditions. All mutants showed a clear decrease in the colony-forming ability under the chosen experimental conditions. Staining with green and red fluorescent nucleic acid stain showed that the mutants fell into two different classes. Seven mutants died during stationary phase; the three other mutants remained viable but did not resume growth after prolonged starvation. Five of the ten Tn5-B20 insertions were cloned from the genomes of the mutant strains. Nucleotide sequence analyses established that the transposon had inserted in five distinctive genes. Database searches revealed that four of the tagged loci corresponded to already characterized genes whose gene products are involved in important cellular processes such as amino acid metabolism or aerobic respiration.

Alleles↗
PubMed1997

Infection of primary cells by adeno-associated virus type 2 results in a modulation of cell cycle-regulating proteins.

It has been demonstrated that infection of primary human cells with adeno-associated viruses (AAV) leads to a decrease in cellular proliferation and to growth arrest. We analyzed the molecular basis of this phenomenon and observed that infection with AAV type 2 (AAV2) had an effect on several factors engaged in the control of the mammalian cell cycle. In particular, all of the pRB family members, pRB, p107, and p130, which are involved in G1 cell cycle checkpoint control, were affected. After infection, a shift from hyper- to hypophosphorylated forms was observed. Cyclins A and B1, which are required for G1/S transition and progression into mitosis, respectively, were downregulated at the transcriptional level as well as at the protein level, whereas the G1 cyclins D1 and E remained unaffected. In addition, the steady-state levels of cyclin-dependent kinases CDK1 and CDK2 and of transcription factor E2F-1 were diminished. Of all the factors known to be involved in phosphorylation of pRB family proteins, only the CDK inhibitor p21WAF1 exhibited a response to AAV2 infection. p21WAF1 mRNA was quickly and progressively upregulated in a p53-independent manner over at least 72 h. Consistent with the increased p21WAF1 protein levels, cyclin E- and cyclin A-dependent kinase activities declined to low levels and E2F-p130-cyclin-CDK2 complexes were disrupted. From these data, we conclude that the major effect of AAV2 infection on primary human fibroblasts appears to be upregulation of p21WAF1 gene expression and thus cell cycle arrest by the suppression of pRB family protein phosphorylation.

Carrier Proteins↗
PubMed1997

Role of renal nerves and endogenous dopamine in amino acid-induced glomerular hyperfiltration.

The present study was performed to clarify whether urinary dopamine excretion (UDAV) and renal nerves are involved in the increase in glomerular filtration rate (GFR) induced by amino acid (AA) infusion. In thiopental-anesthetized rats, L-phenylalanine-free solutions of 10 AA (10%) either with (AATyr, n = 10) or without (AA0, n = 10) L-tyrosine (0.5%) were infused. Compared with baseline values, AATyr increased GFR from 0.83 +/- 0.05 to 1.00 +/- 0.04 ml.min-1.100 g-1 (P < 0.01) and UDAV almost fivefold from 5.81 +/- 0.46 to 28.1 +/- 7.4 pmol.min-1.100 g-1 (P < 0.01). In contrast, infusion of AAo increased GFR as did AATyr but did not significantly change UDAV. The DA2-receptor antagonist S(-)-sulpiride dose-dependently (0.5 to 15 micrograms.min-1.100 g-1) inhibited the GFR response to AA infusion but did not affect UDAV. In rats that had undergone chronic bilateral renal denervation (DNX), the AA-induced hyperfiltration was abolished completely, regardless of whether L-tyrosine was present. DNX did not affect basal UDAV, but the increase in UDAV in response to AATyr was attenuated compared with rats with innervated kidneys. Renal sodium excretion was increased almost twofold due to AA infusion and did not correlate with UDAV significantly. The data suggest 1) that urinary dopamine does not play a significant role in the regulation of kidney function, 2) that renal innervation is essential in the GFR response to systemic AA infusion, and 3) that a dopaminergic mechanism apart from tubular dopamine excretion is involved as well.

Amino Acids↗
PubMed1997

Innervation territories of mechanically activated C nociceptor units in human skin.

Innervation territories of mechanically activated C nociceptor units in human skin. J. Neurophysiol. 78: 2641-2648, 1997. Innervation territories of single mechanically activated C nociceptors in the skin of the leg and foot were explored in normal human subjects. Microneurographic recordings were obtained in the peroneal nerve from 70 mechano-heat responsive (CMH) and 7 mechano-(but not heat) responsive (CM) units. Units were identified by their constant long-latency response to intracutaneous electrical stimulation of their terminals. Responsiveness to mechanical, heat, or transcutaneous electrical stimuli was verified by transient slowing of conduction velocity after activation by such stimuli. We determined their thresholds to mechanical stimuli (mean 33.7 mN, median 30 mN, range 3-750 mN) and heat (mean 42.5 degrees C, median 42.5 degrees C, range 37-49 degrees C). Most mechano-receptive fields (mRFs) were found on the foot dorsum (60 units) and some on the lower leg (14 units) and toes (3 units). Most units had one continuous mRF, but 10 units had more complex fields. Areas of mRFs mapped with a von Frey filament (750 mN) ranged from 10 to 363 mm2 (mean, 106 mm2). The mRFs were oval or irregularly shaped with greatest diameters ranging from 3 to 45 mm. Mean areas of mRFs were largest on the lower leg (198 mm2), smaller on the foot dorsum (88 mm2), and smallest on the toes (35 mm2). Forty-nine of the 77 units had identical mRFs and electro-receptive fields (eRFs). Twenty-six units had larger eRFs than mRFs, whereas the opposite was found for two units only. Areas of eRFs ranged from 16 to 511 mm2 (mean 121 mm2). An estimate of the innervation density based on the present data and the presumed number of C fibers in cutaneous fascicles of the peroneal nerve suggests a considerable overlap of nociceptive endings in the skin. Such overlapping nociceptor innervation in the skin allows for substantial spatial summation in response to punctate noxious stimuli, which may be a prerequisite for high accuracy in localizing painful events from a C-fiber input. The reduction in size of innervation territories distally allows for finer discrimination of spatial dimensions of noxious stimuli distally as compared with proximal regions of the extremities. Mean maximal diameters of the mechano-receptive fields of CMH and CM units on the lower leg (22.3 mm) and foot (15.3 mm) are of similar size as the radius of axon reflex flares evoked by noxious mechanical stimuli in these regions.

Adult↗
PubMed1997

Pyogenic infectious spondylitis: clinical, laboratory and MRI features.

Pyogenic infectious spondylitis (PIS) is an uncommon but serious inflammatory disorder of the discovertebral junction with frequent involvement of neural structures including the spinal cord. We report a series of 41 patients (age range 21-75 years, mean age 59 years) with primary PIS confirmed by signal abnormality of the intervertebral disk and adjacent vertebral bodies on magnetic resonance imaging. The prevailing clinical symptom was focal back pain aggravated by percussion in 90% of patients. Radicular signs or symptoms were present in 59% and spinal cord symptoms in 29% of patients, respectively. Evidence of inflammation consisted of an elevated sedimentation rate in 76%, leukocytosis in 61% and fever in 61% of individuals. Predisposing factors such as diabetes mellitus, previous nonspinal surgery and other sites of infection or inflammation were identified in 17 (41%) patients and 30 (73%) were older than 50 years. The lumbar spine was most often affected and PIS was associated with an epidural abscess in 15 (37%) patients. Increased alertness for PIS in the context of focal back pain with clinical or laboratory signs of inflammation is needed to speed up its detection.

Abscess↗
PubMed1997

Apolipoprotein E polymorphism and silent microangiopathy-related cerebral damage. Results of the Austrian Stroke Prevention Study.

BACKGROUND AND PURPOSE: Microangiopathy-related cerebral damage (MARCD) includes white matter abnormalities and lacunar infarctions and represents a common MRI observation in subjects above 50 years of age. The risk factors of such brain abnormalities are not fully determined. The goal of this study was to determine whether the genetic heterogeneity of apolipoprotein E (apoE) contributes to the occurrence of MARCD. METHODS: Brain MRI (1.5 T) was performed in 280 individuals (ages 50 to 75 years) without neuropsychiatric disease randomly selected from the official register of residents of the city of Graz, Austria. All study participants underwent apoE genotyping, carotid Doppler sonography, electrocardiography, echocardiography, and a complete blood chemistry panel. MARCD was defined as evidence of early confluent and confluent white matter hyperintensities or lacunes. Carotid atherosclerosis was graded on a five-point scale ranging from not present (0) to complete occlusion (5). RESULTS: MARCD occurred in 61 individuals (21%). The distribution of apoE genotypes differed significantly between subjects with and without MARCD (P = .036). Subjects with such findings more commonly had the epsilon 2/epsilon 3 genotype (24.6% versus 10%) at similar frequencies of genotypes containing the epsilon 4 allele. The epsilon 2/epsilon 3 genotype was associated with lower levels of total cholesterol (P = .0009), LDL cholesterol (P = .00001), and apolipoprotein B (P = .00001). Also, there was a nonsignificant trend toward less cardiac disease. Other major vascular risk factors and carotid abnormalities were similar among the various genotypes. Multiple logistic regression analysis created a model of significant MARCD predictors, including age (odds ratio [OR], 1.1 per year), hypertension (OR, 3.4), and the apoE epsilon 2/epsilon 3 genotype (OR, 3.0). CONCLUSIONS: These data suggest an association between the apoE epsilon 2/epsilon 3 genotype and MARCD despite favorable effects on the lipid profile and cardiac disease.

Aged↗