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Biomedical subjects

C Schmidt

Publications and source records attributed to C Schmidt.

At least 271 records · Page 15Linked to original sources
PubMed1996

[Postoperative MRI morphology of the anterior cruciate ligament after primary ligament suture or ligament-plasty. A prospective study of 50 patients].

AIM: Identification of typical postoperative change after anterior cruciate ligament reconstruction (sutures, tendon grafts) and comparison with clinical tests and ultrasound. PATIENTS AND METHODS: 50 patients with anterior cruciate ligament ruptures were examinated with MRI (1.0 T, surface coil, sagittal T1-3DFT-Fast and sagittal spin-echo), US and clinical function tests (Lachmann, pivot-shift, anterior drawer test). RESULTS: In 19 of 21 patients with continuous low-intensity ligament structures in the MRI, knee stability was very good or good in the clinical tests and US. In 17 of 20 patients with a diagnosis of partial rupture at MRI, we also found a stable knee. 5 of 7 patients with the MRI-signs of ligament rupture showed knee stability at US and clinical tests. Furthermore, at MRI we found minor effusions in 10 patients, meniscus tears in 8 patients and ligament impingement in 2 patients. CONCLUSION: MRI is a valuable method for evaluating and assessing anterior ligament reconstructions. We found a good correlation between the continuous low-intensity ligaments at MRI and knee-stability. In contrast there is a bad correlation between discontinuous ligament structures at MRI and clinical stability of the knee. MRI seems to provide more information than US and clinical tests (for example: minor effusion, meniscus tears, ligament impingement, bone lesions).

Anterior Cruciate Ligament↗
PubMed1996

Subcutaneous T-cell lymphoma: a case report and additional observations.

Subcutaneous T-cell lymphoma is rare. Differentiation from several clinically similar entities such as malignant histiocytosis, histiocytic cytophagic paniculitis, Weber-Christian disease, and systemic lymphoma can be difficult. Our patient presented with plaquelike lesions on her lower extremities, fevers, hepatic dysfunction, and a laboratory-proven coagulopathy. Examination of a skin biopsy specimen revealed a benign-appearing histiolymphocytic infiltrate with panniculitis and erythrophagocytosis. Immuno-histochemical staining of the infiltrate demonstrated a predominance of T cells. At autopsy, an atypical T-cell infiltrate was noted in the skin, subcutis, and other organs. Subcutaneous T-cell lymphoma is a rare type of peripheral T-cell lymphoma whose diagnosis is problematic. Based on the initial difficulty finding the lymphomatous infiltrate in our case, it is conceivable that previously reported cases of histiocytic cytophagic panniculitis, malignant histiocytosis, and Weber-Christian disease were in fact unrecognized cases of lymphoma.

Diagnosis, Differential↗
PubMed1996

[Laser-Doppler flowmetry and arterial diseases of the limbs. Correlations with measurement of transcutaneous oxygen pressure].

The place of laser-Doppler flowmetry is not well established among the other techniques of evaluation of local microcirculatory blood flow. We conducted a study in 15 controls (mean age 49.5 yrs, 30 limbs) and 37 patients with peripheral arterial occlusive disease (PAOD) (mean age 59.1 yrs, 67 limbs, 50 mild ischemia and 17 severe ischemia) and assessed the local blood flow with laser-Doppler (Perimed PF3) and transcutaneous oximetry (Hellige Oxymonitor); both probes being heated at 44 degrees C. Transcutaneous oxygen tension (TcpO2 mmHg) and laser-Doppler fluxes (LDF in perfusion units PU) were measured at the foot dorsum in resting horizontal supine position and leg dependency (30 controls, 67 PAOD) and during post-ischemic reactive hyperemia (36 PAOD). The results (mean +/- sd) were compared within each group (controls, mild ischemia, severe ischemia) by means of a paired t-test, between the different groups by a variance analysis and correlations by a Spearman test. LDF decreased from supine position to leg dependency in the control group (24.1 +/- 22.2 PU horizontal vs 19.0 +/- 26.2 dependent, N = 30, p < .05) but not in the PAOD group (mild ischemia respectively 46.0 +/- 41 vs 42.9 +/- 35 PU, N = 50; severe ischemia 41.3 +/- 27 vs 48.6 +/- 42 PU, N = 17). LDF was significantly higher at rest: mild ischemia 46 +/- 41 (N = 50), severe ischemia 41.3 +/- 27 (N = 17) vs controls 24.1 +/- 22 PU (p < .005). LDF increased during hyperemia in controls (peak flux 42.4 +/- 28.9 PU, p < .00001) and in patients with mild ischemia (46.0 +/- 42 vs 32.5 +/- 39 PU at rest, N = 29, p < .005) but not in severe ischemia (29.4 +/- 18 vs 28.7 +/- 33 PU at rest, N = 7). TcpO2 at rest (65.9 +/- 14 mmHg in 30 controls) decreased significantly in mild ischemia (55.6 +/- 16 mmHg, N = 48) and severe ischemia (32.1 +/- 26 mmHg, N = 17, p < .005). On leg dependency, TcpO2 increased in mild ischemia (70.2 +/- 13 leg dependent vs 52.6 +/- 12 mmHg horizontal, N = 21, p < .001) and severe ischemia (respectively 35.6 +/- 24 and 26.1 +/- 15 mmHg, N = 10, p < .01). No correlations were found between LDF parameters and TcpO2 except in patients with severe ischemia (LDF horizontal and dependent with TcpO2 dependent).

Adolescent↗
PubMed1995

Allocation of perineuronal nets and parvalbumin-, calbindin-D28k- and glutamic acid decarboxylase-immunoreactivity in the amygdala of the rhesus monkey.

Lattice-like coatings, known as perineuronal nets, were lectin-cytochemically stained with the Wisteria floribunda agglutinin in the lateral nucleus and the intermediate division of the basal nucleus of the amygdala in rhesus monkeys. Perineuronal nets were demonstrated around neurons with parvalbumin- or calbindin-D28k-immunoreactivity, but not around calretinin-containing cells. In parallel dual-peroxidase staining experiments, it was demonstrated that lattice-like coatings exclusively surround GABAergic neurons in this brain region. The novel finding of calbindin-D28k-immunoreactivity in neurons ensheathed by perineuronal nets amplifies the panel of revealed markers in such nerve cells and indicates their cytochemical heterogeneity.

Amygdala↗
PubMed1995

Strong regulation of slow anion channels and abscisic acid signaling in guard cells by phosphorylation and dephosphorylation events.

Recent evidence suggests that slow anion channels in guard cells need to be activated to trigger stomatal closing and efficiently inactivated during stomatal opening. The patch-clamp technique was employed here to determine mechanisms that produce strong regulation of slow anion channels in guard cells. MgATP in guard cells, serving as a donor for phosphorylation, leads to strong activation of slow anion channels. Slow anion-channel activity was almost completely abolished by removal of cytosolic ATP or by the kinase inhibitors K-252a and H7. Nonhydrolyzable ATP, GTP, and guanosine 5'-[gamma-thio]triphosphate did not replace the ATP requirement for anion-channel activation. In addition, down-regulation of slow anion channels by ATP removal was inhibited by the phosphatase inhibitor okadaic acid. Stomatal closures in leaves induced by the plant hormone abscisic acid (ABA) and malate were abolished by kinase inhibitors and/or enhanced by okadaic acid. These data suggest that ABA signal transduction may proceed by activation of protein kinases and inhibition of an okadaic acid-sensitive phosphatase. This modulation of ABA-induced stomatal closing correlated to the large dynamic range for up- and down-regulation of slow anion channels by opposing phosphorylation and dephosphorylation events in guard cells. The presented opposing regulation by kinase and phosphatase modulators could provide important mechanisms for signal transduction by ABA and other stimuli during stomatal movements.

Journal Article↗
PubMed1995

Adenosinergic modulation of respiratory neurones and hypoxic responses in the anaesthetized cat.

1. The modulatory effects of intracellularly injected adenosine on membrane potential, input resistance and spontaneous or evoked synaptic activity were determined in respiratory neurones of the ventral respiratory group. 2. The membrane potential hyperpolarized and sometimes reached values which were beyond the equilibrium potential of Cl(-)-dependent IPSPs. At the same time, neuronal input resistance decreased. 3. Spontaneous and stimulus-evoked postsynaptic activities were decreased, as were mean respiratory drive potentials. 4. Systemic injection of the A1 adenosine receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX; 0.01-0.05 mg kg-1) resulted in an increase in mean peak phrenic nerve activity when arterial chemoreceptors were denervated. In contrast, phrenic nerve activity decreased when arterial chemoreceptors were left intact. 5. The depressant effect of adenosine on synaptic activity was abolished after systemic DPCPX administration. DPCPX caused an increase in respiratory drive potentials, increased the amplitude of stimulus-evoked IPSPs, and hyperpolarized membrane potential. 6. Administration of DPCPX blocked the early hypoxic depression of stimulus-evoked IPSPs, doubled the delay of onset of hypoxic apnoea and shortened the time necessary for recovery of the respiratory rhythm. 7. The data indicate that adenosine acts on pre- and postsynaptic A1 receptors resulting in postsynaptic membrane hyperpolarization and depression of synaptic transmission. Blockade of A1 receptors increases respiratory activity, indicating that adenosine A1 receptors are tonically activated under control conditions. Further activation contributes to the hypoxic depression of synaptic transmission in the respiratory network.

Adenosine↗
PubMed1995

Scatter factor/hepatocyte growth factor is essential for liver development.

Polypeptide growth factors are important effectors of cell growth and differentiation in vitro and are thought to be critical for processes such as specification of cell fate, tissue growth and organogenesis in vivo. Scatter factor/hepatocyte growth factor (SF/HGF) is the prototype of an emerging family of growth factors that resemble in their domain structure and mechanism of activation the blood proteinase plasminogen. The cellular responses of SF/HGF are mediated by the c-Met tyrosine kinase receptor. Here we report that mice lacking SF/HGF fail to complete development and die in utero. The mutation affects the embryonic liver, which is reduced in size and shows extensive loss of parenchymal cells. In addition, development of the placenta, particularly of trophoblast cells, is impaired. Thus, SF/HGF is essential for the development of several epithelial organs.

Animals↗
PubMed1995

Pharmacokinetics of orally administered cyclosporine in patients with Crohn's disease.

Cyclosporine pharmacokinetics were reported to be influenced in patients with Crohn's disease. To explore the relationship between Crohn's disease and cyclosporine pharmacokinetics, this investigation was performed in 20 patients with varying Crohn's Disease Activity Index (CDAI). A single oral dose of 300 mg of cyclosporine was given and serial blood samples were obtained over 52 hours. Cyclosporine whole blood concentrations were determined by a specific monoclonal radioimmunoassay. Pharmacokinetic parameters were comparable with those of healthy volunteers. No statistically significant difference between the pharmacokinetic parameters of the patients with CDAI values less than 150 and those with CDAI values 150 or greater could be shown. Although several factors associated with the pathology of Crohn's disease theoretically could influence the pharmacokinetics of orally administered cyclosporine, this investigation did not identify statistically significant differences in cyclosporine pharmacokinetics in Crohn's disease patients with different disease activities or different localization of inflammation as compared with healthy volunteers. However, if large parts of the small bowel were removed, a decrease of absorption of cyclosporine could be observed. In any case, it is important to be aware of the clinical variability of Crohn's disease and its potential implications in cyclosporine absorption.

Administration, Oral↗
PubMed1995

Presence of a P1 bacteriophage sequence in transforming plasmids of Pleurotus ostreatus.

Replicative plasmids pP01 and pP02, recovered from Pleurotus ostreatus transformants, contain an insert of bacteriophage origin. These plasmids have been amplified by the polymerase chain reaction (PCR) and have been shown to represent a low-grade component in the initial preparation of the vector pAN7-1. The pP01 and pP02 plasmids share an insert (P01A) of virtual identity with a SmaI-BamHI genomic fragment of P 1 bacteriophage and retain remnants of a polylinker at the 5' end of this fragment. Such an insert undoubtedly represents an in vitro-generated event and did not arise, as suggested previously, by recombination of pAN7-1 with the P. ostreatus genome. The P. ostreatus transformants, however, do select for the minority pP0 plasmid, apparently recognizing the P01A insert as a heterologous or surrogate replicon.

Aspergillus↗
PubMed1995

Improved bronchial cleansing in intensive care patients with a new double-lumen catheter.

OBJECTIVES: A new double lumen catheter with a small channel for application of rinsing solution in deeper parts of the endobronchial tree was developed and its efficiency was tested in two trials. DESIGN: Comparison of the new catheter in 2 controlled studies with the traditional way of suctioning and with conventional endotracheal lavage in a randomized block design. SETTING: Intensive care unit of a university hospital. PATIENTS: In the first study, endobronchial cleansing with the new catheter was compared to the traditional way of suctioning in 12 long-time ventilated patients. In the second study, 28 ventilated patients received either conventional lavage or lavage with the new catheter. INTERVENTIONS: In the first trial the bronchial system of each patient was suctioned 25 times with a conventional technique or cleansed by using the new catheter. In the second study, patients alternatively received conventional lavage 88 times or lavage 88 times with the new catheter. MEASUREMENTS AND RESULTS: Drained secretions averaged 0.84 +/- 0.28 ml using conventional cleaning as compared to 11.02 +/- 0.84 ml with the new catheter. This was accompanied by a significant (p < 0.001) increase in PaO2 of 24.20 +/- 7.90 mmHg after 10 min compared to nearly unchanged PaO2 after normal suctioning. In the second study, suctioned volume was 2.48 +/- 0.21 ml using conventional endotracheal lavage and 10.55 +/- 0.47 ml using the new catheter. Use of the double-lumen catheter induced a significant increase in PaO2 by 30.90 +/- 3.90 mmHg within 10 min. The changes in PaO2 correlated with the drained volume. CONCLUSION: Both studies show that suctioning with the new double lumen catheter allows drainage of a larger volume of secretions and results in a greater improvement of oxygenation.

Aged↗
PubMed1995

Changes of the methylation pattern of the c-myc gene during in vitro aging of IMR90 human embryonic fibroblasts.

DNA modification by cytosine methylation has received considerable interest in the context of mammalian cell differentiation but is discussed controversially with respect to cellular aging. As the expression of c-myc affects strongly cellular aging and terminal differentiation, we have analysed the sequence-specific methylation pattern of the c-myc gene during proliferative aging in vitro of human embryonic fibroblasts. In this study, both, 5-methylcytidine sensitive restriction enzymes as well as genomic sequencing were used. The overall methylation pattern was found essentially stable during proliferative aging. However, specific hypermethylation of exon II during aging was observed. Furthermore, one specific cytidine located in the consensus sequence of the DNA binding factor PEBP2 was found completely methylated during most of the course of proliferative aging of the cells but became demethylated as the cells reached the end of their proliferative life span. Our results indicate the importance of establishing the sequence-specific changes of the methylation pattern of the genome during in vitro aging.

Base Sequence↗
PubMed1995

A mouse model for Down syndrome exhibits learning and behaviour deficits.

Trisomy 21 or Down syndrome (DS) is the most frequent genetic cause of mental retardation, affecting one in 800 live born human beings. Mice with segmental trisomy 16 (Ts65Dn mice) are at dosage imbalance for genes corresponding to those on human chromosome 21q21-22.3--which includes the so-called DS 'critical region'. They do not show early-onset of Alzheimer disease pathology; however, Ts65Dn mice do demonstrate impaired performance in a complex learning task requiring the integration of visual and spatial information. The reproducibility of this phenotype among Ts65Dn mice indicates that dosage imbalance for a gene or genes in this region contributes to this impairment. The corresponding dosage imbalance for the human homologues of these genes may contribute to cognitive deficits in DS.

Alzheimer Disease↗