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Biomedical subjects

G Wolf

Publications and source records attributed to G Wolf.

At least 91 records · Page 5Linked to original sources
PubMed2001

Thrombosis associated with cytomegalovirus infection in patients with ANCA-positive vasculitis.

Three cases of venous thrombosis with pulmonary embolism in two patients associated with underlying antineutrophil cytoplasmic autoantibody (ANCA)-positive vasculitis and reactivated cytomegalovirus (CMV) infection are described. In vitro studies previously have shown that infection of endothelium with CMV increases the release of procoagulant factors and stimulates the expression of adhesion molecules. Because the endothelial cell plays a pivotal role in maintaining the equilibrium between procoagulant and anticoagulant states, injury by ANCA-positive vasculitis and additional infection with CMV may ignite a local thrombosis easily. Although venous thrombosis is uncommon in CMV infection (eg, in the immunosuppressed state after organ transplantation), the combination of vasculitis and reactivated CMV infection may have contributed to injury of the vessel wall with subsequent development of thrombosis. A better awareness of this association could improve morbidity and may lead to prevention of potentially life-threatening pulmonary embolism. Patients with ANCA-positive vasculitis and CMV infection may profit from prophylactic anticoagulant therapy with heparin or low-molecular-weight heparin.

Adult↗
PubMed2001

Online Internet-based robotic telepathology in the diagnosis of neuro-oncology cases: a teleneuropathology feasibility study.

This feasibility study examined the diagnostic accuracy of Internet-based dynamic-robotic telepathology using neuropathology cases. Randomly, 83 cases were selected from the routine diagnostic workload of the Neurosurgical Pathology Laboratory in Poznan, Poland. Telepathology diagnoses were compared with conventional paraffin section diagnosis. The neuropathologists, operating a robotically controlled motorized microscope over the Internet from 3 different Polish cities, individually reviewed the cases using computer workstations. Viewing times ranged from 2 minutes 54 seconds to 32 minutes 12 seconds per case. The mean diagnostic accuracy for telepathology diagnosis was 95%, with 2 of 3 observers achieving 100% diagnostic accuracy. Image quality was judged to be sufficient for correct evaluation, and the viewing times required to establish a final diagnosis by remote video microscopy were acceptable. Generally, user acceptance of robotic telepathology was high.

Adolescent↗
PubMed2001

[Evaluation of a computer-assisted diagnosis system in breast carcinoma].

PURPOSE: Evaluation of a computerassisted diagnosis (CAD) system (R2 linage Checker 1.2). Comparison of the results of three readers with and without knowledge of the computer results. MATERIALS AND METHODS: The mammograms of 52 patients, bilaterally in two planes each, with histologically proven carcinoma of the breast were included in the study. They were first scanned by the CAD machine and subsequently read by three readers with different degrees of experience in two sessions with and without knowledge of the computer results. RESULTS: Of the 91 views of carcinomas, the readers detected 96%, 89%, and 85%, respectively. With CAD, the values rose to 97%, 93%, and 96%. The increase of the first observer was not significant. As for the 49 areas of malignant microcalcifications, the first reader showed a significant decrease of sensitivity, the other two readers showed no significant change. The sensitivity of CAD was 74% for masses and 86% for microcalcifications at a rate of 1.8 false positive markers per image. All but two tumors were correctly marked in at least one plane. CONCLUSIONS: Use of the CAD machine led to a significant increase of sensitivity in the detection of malignant masses by two of three observers. In the case of malignant microcalcifications, and for the most experienced observer, CAD did not improve the results. The most important problem is the high rate of false positive markers.

Breast Neoplasms↗
PubMed2001

Lack of neuronal NOS has consequences for the expression of POMC and POMC-derived peptides in the mouse pituitary.

The relevance of NO in neuroendocrine signalling has been investigated by analysis of cellular expression of pro-opiomelanocortin (POMC) and the POMC-derived peptides beta-endorphin, alpha-melanocyte stimulating hormone and adrenocorticotropin. Expression patterns were studied in the pituitary gland of 150-day old wild-type and neuronal-NOS (nNOS) knock-out mice by using immunohistochemistry, in situ hybridization and Northern blot analysis. Remaining NO-generating capacities in the knock-out mice were demonstrated by immunohistochemical localization of inducible, endothelial and neuronal NOS isoforms. Quantitative analysis revealed that cellular expression of POMC mRNA was drastically reduced in the pituitary of knock-out mice in comparison to controls. In situ hybridization studies demonstrated that this reduction was most pronounced in the intermediate lobe, while the anterior lobe was much less affected. Immunostaining for the proteolytic fragments of POMC was significantly reduced in the intermediate lobe cells of knock-out mice. A moderate reduction of immunostaining for these peptides was also observed in adenopituitary cells of nNOS knock-out mice. Our data demonstrate that the lack of nNOS substantially affects cellular levels of pituitary opioid peptides, which may have consequences for the response of these animals to stress and pain.

Adrenocorticotropic Hormone↗
PubMed2001

A cluster of childhood leukaemias near two neighbouring nuclear installations in Northern Germany: prevalence of chromosomal aberrations in peripheral blood lymphocytes.

PURPOSE: Between 1990 and 1991 a leukaemia cluster was observed in children living close to the combined site of a nuclear power plant and a nuclear research facility in Elbmarsch, a region in Lower Saxony (Germany). We aim to investigate the prevalence of presumably radiation-induced chromosomal aberrations in peripheral blood lymphocytes of children in Elbmarsch and children of a control region in order to find out whether there was an uncontrolled release of radioactive material which resulted in a substantial exposure. MATERIALS AND METHODS: The frequency of dicentric and ring chromosomes in lymphocytes of the peripheral blood in 42 children in Elbmarsch and 30 children in Plön was investigated. Children in both groups had been permanent residents of the study area. RESULTS: The mean frequency of dicentric and ring chromosomes in Elbmarsch was 14/32580 cells (=0.430 x 10(-3); 95% CI 0.24-0.70 x 10(-3) cells), and in Plön it was 17/24065 cells (=0.706 x 10(-3); 95% CI 0.42-1.10 x 10(-3) cells). CONCLUSIONS: No difference in the frequency of dicentric and ring chromosomes was observed between children in Elbmarsch living close to a combined site of a nuclear power plant and a nuclear research facility and children living in the control area Plön. The power of the study to detect a threefold or higher increase in the aberration frequency was at least 0.86.

Adolescent↗
PubMed2001

Ethanol and gene expression in brain.

This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The chairs were Izuru Matusmoto and Peter A. Wilce. The presentations were (1) GABA receptor subunit expression in the human alcoholic brain, by Tracey Buckley and Peter Dodd; (2) NMDAR gene expression during ethanol addiction, by Jorg Puzke, Rainer Spanagel, Walther Zieglgansberger, and Gerald Wolf; (3) Differentially expressed gene in the nucleus accumbens from ethanol-administered rat, by Shuangying Leng; (4) Expression of a novel gene in the alcoholic brain, by Peter A. Wilce; and (5) Investigations of haplotypes of the dopamine D2-receptor gene in alcoholics, by Hans Rommelspacher, Ulrich Finckh, and Lutz G. Schmidt.

Alcoholism↗
PubMed2001

Diagnosis of bone infection using 99m Tc-HMPAO labelled leukocytes.

In order to evaluate the importance of 99mTc-hexamethylpropylene amine oxime (99mTc-HMPAO) leukocyte scintigraphy in the diagnosis of bone infection, we retrospectively reviewed 324 patients. Abnormal findings were seen in 221 patients. In the other 103 cases acute pathological inflammation could be ruled out. The patients with pathological findings were divided into four groups according to the location of the infection. This method showed the localizations of skeletal disorders and its differences to other diagnostic imaging modalities. The underlying abnormalities causing the inflammation were determined. In conclusion, 99mTc-HMPAO leukocyte scintigraphy is still a very sensitive method for either whole body screening or local detection of acute or exacerbated chronic osteomyelitis. The advantages of this method over other diagnostic imaging methods are shown.

Acute Disease↗
PubMed2001

Tissue engineering of peripheral nerves: A comparison of venous and acellular muscle grafts with cultured Schwann cells.

Bioengineering is considered to be the laboratory-based alternative to human autografts and allografts. It ought to provide "custom-made organs" cultured from patient's material. Venous grafts and acellular muscle grafts support axonal regeneration only to a certain extent because of the lack of viable Schwann cells in the graft. We created a biologic nerve graft in the rat sciatic nerve model by implanting cultured Schwann cells into veins and acellular gracilis muscles, respectively. Autologous nerve grafts and veins and acellular muscle grafts without Schwann cells served as controls. After 6 and 12 weeks, regeneration was assessed clinically, histologically, and morphometrically. The polymerase chain reaction analvsis showed that the implanted Schwann cells remained within all the grafts. The best regeneration was seen in the control; after 12 weeks the number of axons was increased significantly compared with the other grafts. A good regeneration was noted in the muscle-Schwann cell group, whereas regeneration in both of the venous grafts and the muscle grafts without Schwann cells was impaired. The muscle-Schwann cell graft showed a systematic and organized regeneration including a proper orientation of regenerated fibers. The venous grafts with Schwann cells showed less fibrous tissue and disorganization than the veins without Schwann cells, but failed to show an excellent regeneration. This might be attributed to the lack of endoneural-tube-like components serving as scaffold for the sprouting axon. Although the conventional nerve graft remains the gold standard, the implantation of Schwann cells into an acellular muscle provides a biologic graft with basal lamina tubes as pathways for regenerating axons and the positive effects of Schwann cells producing neurotrophic and neurotropic factors, and thus, supporting axonal regeneration.

Animals↗
PubMed2001

Retinoic acid homeostasis: retinoic acid regulates liver retinol esterification as well as its own catabolic oxidation in liver.

Retinol is stored in liver in the form of its esters. The retinol-esterifying enzyme lecithin:retinol acyltransferase (LRAT) catalyzes the conversion of retinol into its storage form. Expression of the LRAT mRNA is induced by retinoic acid (RA), or by dietary vitamin A, and is downregulated upon vitamin A depletion. RA also induces the expression in liver of the mRNA for CYP26, the enzyme that disposes of excess RA by oxidizing RA to 4-oxo-RA. CYP26 is downregulated upon vitamin A depletion.

Acyltransferases↗
PubMed2001

The uncoupling proteins UCP2 and UCP3 in skeletal muscle.

The uncoupling protein UCP1 aids the production of heat by uncoupling respiration from oxidative phosphorylation in brown fat of rodents. UCP1 is down-regulated during starvation to conserve energy. Levels of other uncoupling proteins named UCP2 and UCP3, which are present in skeletal muscle, increase during starvation without changing heat production. Transgenic mice ectopically over-expressing UCP3 lost weight and had less adipose tissue than controls, although they were hyperphagic. It was proposed that muscle UCP3 regulated fat oxidation rather than thermogenesis.

Animals↗
PubMed2001

The enzymatic cleavage of beta-carotene: end of a controversy.

The central cleavage of dietary beta-carotene to retinal was found to be the predominant mechanism whereby retinoids were formed in vivo in rats; apo-carotenals, indicative of eccentric cleavage of beta-carotene, were only a minor component (<5% of retinoids). A gene from maize that codes for a plant carotenoid cleavage enzyme was used to isolate a homologous gene from Drosophila. This gene, when transfected into an E Coli strain capable of synthesizing and accumulating beta-carotene, caused the central cleavage of beta-carotene, forming exclusively retinoids. The enzyme that the gene codes for, beta-carotene-15,15'-dioxygenase, was purified and characterized.

Animals↗
PubMed2001

Insulin resistance associated with leptin deficiency in mice: a possible model for noninsulin-dependent diabetes mellitus.

Leptin deficiency, found in transgenic lipodystrophic mice and in obese (ob/ob) mice, was shown to cause increased lipogenesis in liver, through action of the sterol regulatory element-binding protein-1c, and increased liver gluconeogenesis, through a decline in the insulin receptor substrate-2. The resulting stimulation of insulin secretion by the pancreas owing to high blood glucose initiates a vicious cycle of insulin resistance.

Animals↗
PubMed2001

Atrial natriuretic peptide attenuates ANG II-induced hypertrophy of renal tubular cells.

ANG II arrests LLC-PK1 cells in the G1 phase of the cell cycle and induces hypertrophy, an effect mediated by induction of p27Kip1. We studied whether atrial natriuretic peptide (ANP) may modulate ANG II-induced hypertrophy and p27Kip1 expression in tubular LLC-PK1 cells. ANP, through its fragments 3---28 and 4---27, prevented ANG II-induced cell cycle arrest. ANP inhibited >80% of ANG II-induced p27Kip1 protein expression (Western blots). ANP stimulated expression of MKP-1, a phosphatase involved in dephosphorylation of p44/42 mitogen-activated protein (MAP) kinase, up to 12 h. ANP prevented the ANG II-mediated phosphorylation peak of MAP kinase after 12 h of stimulation. 8-Bromo-cGMP mimicked all the effects of ANP. Transfection with MKP-1 antisense, but not sense, oligonucleotides abolished the modifying role of ANP on ANG II-mediated cell cycle arrest. The effect of ANP on ANG II-mediated hypertrophy of LLC-PK1 cells is regulated on the level of MAP kinase phosphorylation, a key step in the induction of p27Kip1. Although ANP and ANG II both stimulate generation of reactive oxygen species, ANP additionally induces expression of MKP-1, leading to interference with ANG II-mediated MAP kinase phosphorylation.

Angiotensin II↗