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Biomedical subjects

M Riedel

Publications and source records attributed to M Riedel.

At least 73 records · Page 4Linked to original sources
PubMed1998

Blood-cerebrospinal fluid barrier impairment as indicator for an immune process in schizophrenia.

An impairment of the blood-cerebrospinal fluid barrier (BCB) has repeatedly been described in schizophrenic patients. A BCB impairment can be due to vascular leakage during an inflammatory process, or to neuroleptic treatment. The soluble intercellular adhesion molecule-1 (sICAM-1) has been demonstrated to be a reliable marker for an inflammatory process causing an BCB impairment. To clarify the basis of a BCB impairment in schizophrenic patients, we measured the sICAM-1 levels in CSF of 40 schizophrenic patients. High concentrations of sICAM-1 were found to be related to high concentrations of albumin, IgG and total protein in CSF. A BCB impairment was associated with high levels of sICAM-1. Our data indicate an inflammatory mechanism of BCB impairment in schizophrenics and should enrich the discussion on an expanded immunological diagnosis in schizophrenia.

Adult↗
PubMed1998

Autoantibodies against 60-kDa heat shock protein in schizophrenia.

Immunological abnormalities in schizophrenic patients have been reported for many years. However, the question of whether these parameters are involved in the pathophysiology of the disorder or represent treatment effects is still not answered. We investigated a combination of humoral and soluble immune parameters in 30 unmedicated schizophrenic patients before and during antipsychotic treatment and in 31 healthy controls. The aim of our study was to unravel an underlying immune process, to elucidate the influence of neuroleptic treatment and to identify a subgroup of schizophrenics. Antibodies against human 60-kDa heat-shock protein (HSP60), serum levels of soluble ICAM-1 and IL-2R were determined and correlated with parameters of blood-brain barrier and of psychopathology. In 10% of the drug-free but in 20% of the medicated schizophrenics, especially in females, we observed immunoreactivity against HSP60, high levels of IgG in CSF and a blood-brain barrier impairment. The high HSP antibody titres correlated with high levels of sIL-2R and sICAM-1. Only one of the controls showed antibodies against HSP60. Our results suggest that the observed immunological alterations are more pronounced during neuroleptic treatment than in the drug-free state. Whether or not this differential response to treatment with altered antibody production represents a subgroup of patients has yet to be determined.

Adolescent↗
PubMed1998

Ultrafiltration membrane surfaces with grafted polymer 'tentacles': preparation, characterization and application for covalent protein binding.

Ultrafiltration (UF) membranes from polysulfone (PSf) were functionalized by heterogeneous photo-initiated graft copolymerization of acrylic acid (AA). With radiation susceptible PSf, only proper selection of the UV energy (lambda > 350 nm; for selective excitation of the photoinitiator) yielded membranes with preserved UF barrier layer. Possibilities for adjusting structure and morphology of the graft polymer (g-PAA) layer by variation of functionalization parameters such as AA concentration and UV irradiation time were investigated. Very long grafted chains (Mw > 10(5) g mol(-1)) at varied grafting density (GD = 0.01 ... 1.2 nmol cm(-2), relative to the outer surface area) were obtained. Partial penetration of the UF barrier layer by g-PAA was verified. Covalent immobilization of bovine serum albumin (BSA), gamma-globulin (gamma-Gl) and alkaline phosphatase (APh) was achieved by coupling with a water soluble carbodiimide. Bound BSA and gamma-Gl amounts were up to gamma = 10 microg cm(-2), for membranes accessible only from the outer surface thus not using the entire pore volume. Locally addressed covalent protein immobilization after photo-patterning the PSf surface could be visualized with a fluorescent FITC-BSA conjugate. A strong salt effect onto immobilized APh activity (increase with NaCl concentration) was observed, indicating internal transport/accessibility limitations in the g-PAA layer. Correlations between PAA structure (Mw, GD) and accessibility (from BSA or gamma-G1 binding and APh activity) could be established. The 'tentacle' g-PAA functionalized PSf UF membranes having preserved UF barrier and, e.g., with surface-bound receptors will find application in cell cultures under diffusion or perfusion conditions.

Acrylic Resins↗
PubMed1998

Preoperative bronchoscopic assessment of airway invasion by esophageal cancer: a prospective study.

BACKGROUND: Bronchoscopy is frequently used to assess invasion of esophageal cancer into the tracheobronchial tree. Prospective studies evaluating the role of bronchoscopy in pretherapeutic staging of esophageal cancer are lacking. STUDY OBJECTIVES: To evaluate the diagnostic utility of fiberoptic bronchoscopy for the assessment of airway involvement by esophageal carcinoma and its resectability. PATIENTS AND METHODS: In a prospective study, we analyzed 150 bronchoscopies in 116 consecutive patients with potentially operable esophageal carcinoma, and correlated the findings with other staging modalities, intraoperative evaluation, and histopathologic data. RESULTS: One unknown additional bronchial cancer was found. In 32% of bronchoscopies performed in patients with esophageal cancer located above the tracheal bifurcation, some macroscopic abnormality was detected in the trachea and main bronchi, with mobile protrusion of the posterior tracheal wall being the most frequent abnormality (20.7%). When compared with histologic results, normal macroscopic appearance of the trachea and main bronchi had a negative predictive value of 98.5%, but the positive predictive value of all macroscopic abnormalities for the diagnosis of airway involvement was low, particularly after radiation therapy. The overall accuracy of bronchoscopy with multiple brush cytology and biopsy sampling in proving or excluding airway invasion in patients with otherwise operable conditions was 95.8% (95% confidence interval, 88.3 to 99.1%). Bronchoscopy was the sole decisive staging procedure, resulting in exclusion from surgery because of airway invasion, in 9.7% of patients with otherwise potentially operable conditions. The results of bronchoscopy and CT were discordant in 40% of the patients; the specificity and positive predictive value were higher for bronchoscopy than for CT. CONCLUSIONS: When performed as the last investigation in the staging workup, bronchoscopy with biopsy and brush cytology is a very accurate procedure in evaluating possible airway invasion of esophageal cancer; macroscopic findings alone are not reliable.

Bronchial Neoplasms↗
PubMed1997

Saccades in Gilles de la Tourette's syndrome.

Gilles de la Tourette's syndrome (GTS) is presumed to be an inherited disorder with an unclear pathophysiology. An involvement of the basal ganglia is suspected. Besides vocal tics, one of the main symptoms is the presence of motor tics. As eye movements are a specialized part of the motor system, we investigated whether they differed in some typical way in GTS patients. To study the control of saccades in GTS, different paradigms were used to elicit saccades, which were either externally triggered and visually guided or internally triggered and without visual target. GTS patients (n = 10) showed a significant increase of the latency of antisaccades, a highly impaired performance of sequences of memory-guided saccades, and an isolated reduction of the peak velocity in the antisaccades. Overall the results were similar to those found with similar paradigms in patients with Huntington's disease (HD). In analogy to the known pathology of HD, these findings can be attributed to ascending loops from the basal ganglia that inappropriately activate the frontal cortex, especially some of the eye movement-related areas there. This impairment seems to be a rather specific effect, since some oculomotor features that are preserved by structures of the frontal cortex, such as the effect of a fixation target on saccadic latency ("gap effect"), were normal.

Adolescent↗
PubMed1997

Neuroleptic treatment increases soluble IL-2 receptors and decreases soluble IL-6 receptors in schizophrenia.

The cytokines interleukin-2 (IL-2) and interleukin-6 (IL-6) increase during immune activation, they are released from activated astrocytes and microglial cells in the central nervous system (CNS), and they are able to enhance the catecholaminergic neurotransmission. This study focused on the soluble receptors of IL-2 and IL-6 (sIL-2R, sIL-6R) as a part of the regulation system of IL-2 and IL-6. We studied serum levels of sIL-2R in 30 schizophrenic patients not under neuroleptic medication during an acute exacerbation of the disease and reexamined these patients under neuroleptic treatment after clinical improvement. The sIL-6R levels of 39 schizophrenic patients were estimated under the same conditions. The results were compared with the levels of sIL-2R and sIL-6R in 42 healthy controls. No difference was found between the schizophrenic patients before neuroleptic treatment and the healthy controls. During neuroleptic treatment, however, there was a significant increase of sIL-2R levels and a significant decrease of the sIL-6R levels between the pre- and post-conditions. In comparison with healthy controls, the treatment group also showed increased sIL-2R levels and decreased sIL-6R levels. These results suggest that treatment with neuroleptics is associated with increased sIL-2R and decreased sIL-6R. Since sIL-2R bind and inactivate IL-2, whereas sIL-6R form an active complex with IL-6, the increase of sIL-2R and the decrease of sIL-6R together may reflect a functional down regulation of these activating cytokines. This suggests that neuroleptic therapy has a differentiated immunomodulatory effect.

Adolescent↗
PubMed1997

[Immunoglobulin therapy in Gilles de la Tourette syndrome].

It has known for a long time that Sydenham's chorea and tics, as seen in Gilles de la Tourette's syndrome (GTS), are phenomenologically very similar. Tics may occur as symptoms of acute Sydenham's chorea or persist over years as residual symptoms. Investigating of children suffering from GTS, including obsessive-compulsive symptoms, have provided signs of a poststreptococcal autoimmune process but also shown that treatment based on immunological interventions has been effective. We treated a 14-year-old boy showing all diagnostic criteria of GTS, familial susceptibility, and an increase in the antibody titer of streptococcal antigens with 75 immunoglobulins i.v. over 5 days. Response to this therapy was good regarding motor tics, vocal tics, and behavioral symptoms such as disturbed impulse control which still persisted after 9 months. These findings and the successful therapy underline reports of the literature and point to a pathogenetic mechanism of an immunologically triggered disturbance of the striatal dopaminergic system, at least in a subgroup of GTS.

Adolescent↗
PubMed1997

Contractile responses to histamine, serotonin, and angiotensin II are impaired by 17 beta-estradiol in human internal mammary arteries in vitro.

There is accumulating evidence that estrogen replacement therapy protects against the development of coronary atherosclerosis and myocardial infarction in postmenopausal women. The mechanism of this protective effect is uncertain. The purpose of the present study was to determine whether 17 beta-estradiol acutely modifies vascular smooth muscle contractile responses to various agonists in human arteries in vitro. Human mammary artery rings were obtained during aortocoronary bypass operations. Rings were suspended in organ baths for isometric tension measurements. Concentration response curves induced by serotonin (0.01-30 mumol/l), histamine (0.01-300 mumol/l), and angiotensin II (0.1-100 nmol/l) were generated after pre-incubation for 30 min with either 17 beta-estradiol (3 mumol/l) or solvent (0.2% ethanol). The presence of 17 beta-estradiol significantly reduced the maximal contractile effects induced by histamine, serotonin, and angiotensin II, but not by 80 mmol/l potassium chloride. It is concluded that short-term incubation with 17 beta-estradiol reduces the maximal contractile responses to serotonin, histamine, and angiotensin II. These modulating effects of estrogen on vascular tone may contribute to the proposed beneficial role of estrogen replacement therapy on the incidence of myocardial infarction in postmenopausal women.

Aged↗
PubMed1996

Regional heterogeneity of cerebral blood flow response to graded volume-controlled hemorrhage.

OBJECTIVE: Of the animal models of human hemorrhagic shock, the volume-controlled hemorrhage model appears to come closer to the clinical situation than the commonly used pressure-controlled model, since the volume-controlled model allows regulatory adjustment of blood pressure. The effects of volume-controlled hemorrhage on local cerebral blood flow (LCBF) of conscious animals are not known. The present study investigates specific reaction patterns of LCBF in comparison to mean cerebral blood flow (CBF) during graded volume-controlled hemorrhagic shock in conscious rats. METHODS: Conscious, spontaneously breathing, and minimally restrained rats were subjected to different degrees of volume-controlled hemorrhage (taking either 25, 30, 35, or 40 ml arterial blood/kg body weight (b.w.). Thirty minutes after the completion of blood taking, LCBF was determined during hemorrhagic hypovolemia using the autoradiographic iodo (14C) antipyrine method. A group of untreated rats (no hemorrhage) served as controls. LCBF was determined in 34 defined brain structures and mean CBF was calculated. RESULTS: During less severe hemorrhage (25 and 30 ml/kg b.w.) mean CBF was significantly higher than in the control group (+19% and +25%). During severe hemorrhage (35 and 40 ml/kg b.w.) mean CBF remained unchanged compared to the control values, although significant increases in LCBF could be detected in many of the brain structures analyzed (maximum +44%). The mean coefficient of variation of CBF was increased, indicating a larger heterogeneity of LCBF values at shed blood volumes of 35 and 40 ml/kg b.w. CONCLUSIONS: A comprehensive and novel description of the local distribution of CBF during graded volume-controlled hemorrhage in conscious rats shows unexpected increases in LCBF and mean CBF. This "hypovolemic cerebral hyperemia" might be caused by endogenous hemodilution, thus maintaining the blood supply to the brain during hypovolemic shock.

Animals↗
PubMed1996

Noncardiogenic pulmonary edema.

Pulmonary edema is a consequence of high pressures in the pulmonary microcirculation (predominantly capillaries) or an increase in the permeability of the alveolar-capillary barrier (generally of its endothelial aspect) or a combination of both. It occurs when the rate of transudation from the capillaries exceeds the rate of lymphatic drainage from the interstitium. If the plasma oncotic pressure is low due to hypoproteinemia, transudation of fluid occurs at lower pressures. Permeability pulmonary edema is strongly influenced by fluctuations in pulmonary capillary pressures: an increase in pulmonary capillary pressure can add a large component of hemodynamic pulmonary edema to that originating in leaky vessels. Noncardiogenic forms of pulmonary edema are described.

Humans↗
PubMed1995

Pulsatile growth hormone secretion in normal-weight and obese men: differential metabolic regulation during energy restriction.

Metabolic changes such as obesity and fasting modulate pulsatile growth hormone (GH) release in man, but the underlying mechanisms are still elusive. We studied the temporal pattern of pulsatile GH release in five normal-weight men (mean +/- SD: age, 29.8 +/- 4.9 years; body mass index [BMI], 24.3 +/- 1.8 kg/m2) and five obese men (age, 27.8 +/- 4.8 years; BMI, 38.9 +/- 4.8 kg/m2) during their regular energy consumption and the last 24 hours of a 96-hour fasting period. GH plasma levels were determined at 10-minute intervals and glucose level was measured every 20 minutes. GH pulse analysis was performed with three different algorithms. Insulin-like growth factor-I (IGF-I), IGF-II, IGF-binding proteins (IGFBP-1, -2, and -3), and IGF-binding capacity (IGF-BC) were evaluated in samples collected at 7:00 AM, 3:00 PM, and 11:00 PM. Twenty-four-hour mean GH was basally higher in normal subjects (1.1 +/- 0.6 mU/L) than in overweight subjects (0.4 +/- 0.2, P < .01 v normal). The significant fasting-induced GH increase in normal-weight men (to 5.6 +/- 2.2 mU/L, P < .05 v basal) was inversely related to BMI (r = -.86, P = .0006). GH pulse amplitudes but not frequencies were different for both groups and were increased by fasting in normal subjects but not in obese subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Gangliocytomas of the sellar region--a review.

Gangliocytomas are benign, slow growing neuronal tumors and are found for the most part in children and young adults. They are most often localized in either the spinal cord or the cerebral hemispheres. Gangliocytomas in the sellar region are extremely rare and only 43 such tumors (including 4 own cases) have ever been described in the literature. Although these tumors are genuine rarities without any epidemiological importance, they do provide some interesting information on tumorigenesis of pituitary adenomas: 65% of the sellar gangliocytomas are associated with a pituitary adenoma. 74% of patients with these tumors suffered hormonal oversecretion of at least one of the pituitary hormones (mostly growth hormone). With only one exception, the hypothalamic releasing hormone corresponding to the hormonal oversecretion syndrome could be demonstrated in the gangliocytoma immunohistochemically. Ultrastructural studies could demonstrate close cell to cell contacts between adenoma and gangliocytome cells. All these data support the hypothesis that chronic overstimulation by hypothalamic releasing hormones play a role in the development of hormone secreting pituitary adenomas. However, in contrast to sellar gangliocytemas, extrahypothalamic tumors secreting excessive hypothalamic hypophysiotropic hormones have never been associated with a pituitary adenoma. They have only been associated with pituitary cell hyperplasia. Therefore, the hypothesis can be made that hypothalamic releasing hormones only promote but do not initiate tumorigenesis of pituitary adenomas.

Adult↗
PubMed1995

Vascular responses to 17 beta-oestradiol in postmenopausal women.

The vascular responses to 17 beta-oestradiol were examined in 23 postmenopausal women (59 +/- 7 years [mean +/- SD]) using a placebo-controlled double-blind crossover design. All women received 1 mg 17 beta-oestradiol or placebo (P) sublingually on consecutive days in random order. Axial diameters and blood flow rates of the left common femoral arteries were determined before and 60-80 min after application of verum or placebo as well as 10-30 min after 10 mg isosorbide dinitrate (ISDN) with a quantitative duplex ultrasound technique. Oestradiol induced a vasodilation of femoral arteries (+6.4 +/- 4.1% of basal, P < 0.001 vs. basal and P), the vessel diameter was unchanged with placebo (+0.7 +/- 2.1%). The blood flow rate increased significantly after oestradiol application (+30 +/- 28%, P < 0.05 vs. basal and P), but not after placebo (+11 +/- 21%). Mean blood pressure and heart rate remained constant with both drugs. Despite its vasodilatory effect, ISDN significantly reduced the arterial blood flow after pretreatment with oestradiol and placebo, probably through cardiac preload reduction. In conclusion, 17 beta-oestradiol alters the vascular tone of systemic arteries resulting in a vasodilation and increase of blood flow. We suggest that these direct vascular actions may contribute to the preventive properties of oestrogens on cardiovascular diseases in postmenopausal women.

Aged↗
PubMed1994

Effects of alpha-inhibin-92 fragments and alpha-inhibin-92 antiserum on the control of follicle-stimulating hormone release in male rats.

Alpha-inhibin-92 (alpha-IB-92) has been characterized from human seminal plasma and found to be active in suppressing FSH release in vitro and in vivo. In order to determine if smaller fragments of this 92 amino acid peptide would still be active to suppress FSH release, we have evaluated 5 of these fragments for their effects on FSH and LH release in the present study. Five alpha-IB-92 fragments (1-34, 1-46, 35-65, 35-92 and 66-92) were synthesized and injected intravenously (iv) into castrated adult rats (2 days post operation). Only fragments alpha-IB-92-(35-65) and alpha-IB-92-(66-92) significantly lowered plasma FSH, but not LH, at doses of 10 micrograms. These fragments exerted a preferential FSH-suppressing effect, but their activities were less than that of alpha-IB-92. In view of the rapid action of these peptides and the preferential FSH suppressing effect, they could be useful clinically to suppress FSH release. To determine the possible physiologic significance of alpha-IB-92, we injected antiserum raised against alpha-IB-92 into immature male rats and evaluated its effects on FSH and LH release. Normal rabbit serum (NRS) or anti-alpha-IB-92 serum was injected iv through indwelling jugular catheters into conscious, unrestrained 18 day-old male rats. Blood samples (0.2 ml) were collected at various intervals. Intravenous injection of alpha-IB-92 antiserum (0.1 ml/rat) selectively elevated plasma levels of FSH but not LH from 2-8 h post-injection in 18 day-old male rats (P < 0.01). Since immunoneutralization of alpha-IB-92 significantly elevated FSH release in immature rats, alpha-IB-92 has a physiological inhibiting role in control of FSH but not LH release at this stage of development.

Animals↗
PubMed1994

Biological and clinical investigations of a glass ionomer base material.

OBJECTIVES: The purpose of this study was to investigate the biological properties of a new glass ionomer base material containing strontium glass. METHODS: The glass ionomer base material (Base Line, De Trey Dentsply) was tested for cytotoxicity using a standard agar diffusion test, for its effect upon the pulp in subhuman primates, and in a clinical study as base beneath both composite fillings and amalgam fillings. RESULTS: The material showed a cytotoxicity pattern similar to reference materials, a zinc phosphate cement and a reference glass ionomer base material, which are used successfully in clinical applications. With the pulp/dentin usage test in subhuman primates, there were no statistically significant differences between the experimental glass ionomer base material and the negative control group if bacterial contamination of the cavity floor or direct contact with the pulp was avoided. The results of the clinical study also indicated no pulp damage after one year. SIGNIFICANCE: The experimental glass ionomer base material proved to be acceptable both biologically and clinically.

Analysis of Variance↗