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Biomedical subjects

U Schmidt

Publications and source records attributed to U Schmidt.

At least 199 records · Page 11Linked to original sources
PubMed1994

The antigonadotrophic effect of melatonin in Syrian hamsters is modulated by prostaglandin.

PGE2 was shown to play an essential role in the gonado-inhibiting effect of melatonin in Syrian hamsters by transforming the neuroendocrine signal to gonadal reactivity. Prostaglandin is a vital link in the transduction of photoperiodic information into gonadal function and the difference in its levels brought about by melatonin given at different times of the day could explain the phenomenon why gonadal involution occurs only upon administration of melatonin towards the end of the day. It appears also that the melatonin signal is decoded in the pituitary, probably involving the short loop negative feedback of LH on LH-RH hormones.

Animals↗
PubMed1994

Urapidil permeates the intact blood-brain barrier.

OBJECTIVE: To determine the plasma and cerebrospinal fluid (CSF) levels of urapidil after i.v. administration and the effect on CSF serotonin and 5-hydroxyindoleacetic acid (5-HIAA) concentrations. DESIGN: Open, single-dose study. SETTING: Post-surgery following neurosurgical removal of the hypophysis (n = 5) or aneurysm clipping (n = 1). PATIENTS: 6 patients, aged 32-71 years, with intact blood-brain barrier (BBB); 1 patient was studied twice. INTERVENTIONS: Single dose of 25 mg urapidil i.v. as prophylaxis of BP increase during extubation or as treatment of hypertensive episodes. MEASUREMENTS AND RESULTS: Urapidil, serotonin and 5-HIAA were measured by HPLC in CSF during 8 h after urapidil administration. Urapidil was detected in CSF as soon as 5 min after injection in 3 patients. The concentration ratio of plasma/CSF after the distribution phase was about 5:1. No significant effect on serotonin and 5-HIAA in CSF was seen. CONCLUSION: After administration of a therapeutic dose, urapidil permeates the BBB and may interact with central 5-HT1A-receptors.

Adrenergic alpha-Antagonists↗
PubMed1994

The prevalence of eating disorders in thyroid disease: a pilot study.

The aim of this study was to determine the prevalence of eating disorders and partial syndromes in women with thyroid disease. Female patients between the ages of 18 and 45 who attended a specialist thyroid clinic, in 1990, were asked to complete two self-report questionnaires (Bulimic Investigatory Test, Edinburgh, BITE and General Health Questionnaire, GHQ). High scoring patients were invited to attend for a research interview. The case notes of non-responders were examined. Seventy-three patients were entered into the study and 50 subjects returned their questionnaires (69%). Eleven patients scored highly on the BITE, nine of these patients also scoring highly on the GHQ, as did a further 12 patients. Ten patients were interviewed; of these, three patients (4%) met DSM111R criteria for bulimia nervosa and three patients met criteria for an eating disorder not otherwise specified. These results suggest that there is an increased prevalence of eating disorders in women thyroid patients.

Adolescent↗
PubMed1994

Well-differentiated (oncocytoid) neuroendocrine carcinoma of the larynx with multiple skin metastases: a brief report.

A 63-year-old woman presented with a history of increasing dysphagia of about two weeks duration. Laryngoscopy revealed a nonulcerated supraglottic epitheliomatous lesion that morphologically appeared well-differentiated and distinctly oncocytoid. Although the tumour lacked any criteria for malignancy such as cellular atypia, pleomorphism or necroses, it recurred twice after primary surgery and later gave rise to multiple painful skin metastases. The diagnosis of an oncocytoid differentiated neuroendocrine carcinoma of the larynx (laryngeal carcinoid) was made. Misinterpretation of laryngeal carcinoids is common, but can be avoided if one is familiar with this rare variant of laryngeal neoplasms.

Carcinoid Tumor↗
PubMed1994

Influence of halothane on the effect of cAMP-dependent and cAMP-independent positive inotropic agents in human myocardium.

Volatile anaesthetics have a variety of effects on the myocardium, namely a negative inotropic effect and a catecholamine sensitizing effect. The present study was designed to see if the hydrocarbon anaesthetics interact specifically with subcellular targets of the myocardial cell, by examining the effects of halothane in the presence of positive inotropic agents with different mechanisms of action. Experiments were performed in isolated electrically driven left ventricular preparations (1 Hz, 37 degrees C, Ca2+ 1.8 mmol litre-1) from human hearts obtained at cardiac surgery. The concentration-response curves of noradrenaline, milrinone, BayK 8644 and Ca2+ were investigated in the absence and in the presence of halothane. Halothane enhanced the efficacy of noradrenaline and milrinone but not of Ca2+ or BayK 8644. The potency of milrinone was also increased by halothane, whereas the potency of BayK 8644 was decreased and those of noradrenaline and Ca2+ were unchanged. Halothane differentially influences the effects of agents with different positive inotropic mechanisms. This experimental approach can be taken as a functional method to localize the mechanisms of action of the inhalation anaesthetics in human myocardium, namely sensitization of cAMP formation and interaction with L-type Ca2+ channels.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1994

Effects of single intravenous administration of urapidil and diltiazem in patients with nonfixed pulmonary hypertension secondary to chronic obstructive lung disease.

In patients with chronic obstructive lung disease (COLD), pulmonary hypertension (PH) often develops in addition over the course of years. In this study, the acute effects of urapidil and diltiazem in patients with mild PH secondary to COLD were investigated. Eighteen male and 2 female patients, aged 42-78 years, received in randomized, single-blind fashion single intravenous (i.v.) doses of either urapidil (35-50 mg, n = 10) or diltiazem (25 mg, n = 10). Mean pulmonary artery pressure (MPAP), pulmonary wedge pressure (PWP), mean arterial blood pressure (BP) (MAP), and arterial and central venous blood gases were determined at rest and during exercise (starting with 25 W with increases in 25-W steps) before and after drug administration. Urapidil caused a significant reduction in MPAP (from 19 +/- 7 to 15 +/- 4 mm Hg, p < 0.01), PWP (from 9 +/- 3 to 7 +/- 2 mm Hg, p < 0.05), but not significantly in MAP at rest, whereas with diltiazem only MAP was decreased (from 103 +/- 14 to 98 +/- 12 mm Hg, p < 0.05) and MPAP and PWP were not significantly increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1994

Cloning, heterologous expression, and sequencing of a novel proline iminopeptidase gene, pepI, from Lactobacillus delbrueckii subsp. lactis DSM 7290.

The gene for proline iminopeptidase from Lactobacillus delbrueckii subsp. lactis DSM 7290 coding for an enzyme that hydrolyses the synthetic substrate L-prolyl-beta-naphthylamide (Pro-beta NA) was cloned in Escherichia coli. An enzymic plate assay was used to screen for positive clones. The gene, designated pepI, was subcloned into vector pUC18 and sequenced. The nucleotide sequence revealed an 882 bp open reading frame encoding 294 amino acids, coding for an enzyme with a calculated molecular mass of 32883 Da. By cloning under control of the lac promoter the peptidase was highly expressed. Sequence analysis showed that pepI is of a new sequence type, distinct from all peptidases so far sequenced. Amino acid homology to the active site of a Pseudomonas putida esterase and inhibitor studies of the enzyme imply involvement of a serine residue in catalysis.

Amino Acid Sequence↗
PubMed1994

The failing human heart is unable to use the Frank-Starling mechanism.

There is evidence that the failing human left ventricle in vivo subjected to additional preload is unable to use the Frank-Starling mechanism. The present study compared the force-tension relation in human nonfailing and terminally failing (heart transplants required because of dilated cardiomyopathy) myocardium. Isometric force of contraction of electrically driven left ventricular papillary muscle strips was studied under various preload conditions (2 to 20 mN). To investigate the influence of inotropic stimulation, the force-tension relation was studied in the presence of the cardiac glycoside ouabain. In skinned-fiber preparations of the left ventricle, developed tension was measured after stretching the preparations to 150% of the resting length. To evaluate the length-dependent activation of cardiac myofibrils by Ca2+ in failing and nonfailing myocardium, the tension-Ca2+ relations were also measured. After an increase of preload, the force of contraction gradually increased in nonfailing myocardium but was unchanged in failing myocardium. There were no differences in resting tension, muscle length, or cross-sectional area of the muscles between both groups. Pretreatment with ouabain (0.02 mumol/L) restored the force-tension relation in failing myocardium and preserved the force-tension relation in nonfailing tissue. In skinned-fiber preparations of the same hearts, developed tension increased significantly after stretching only in preparations from nonfailing but not from failing myocardium. The Ca2+ sensitivity of skinned fibers was significantly higher in failing myocardium (EC50, 1.0; 95% confidence limit, 0.88 to 1.21 mumol/L) compared with nonfailing myocardium (EC50, 1.7; 95% confidence limit, 1.55 to 1.86 mumol/L). After increasing the fiber length by stretching, a significant increase in the sensitivity of the myofibrils to Ca2+ was observed in nonfailing but not in failing myocardium. These experiments provide evidence for an impaired force-tension relation in failing human myocardium. On the subcellular level, this phenomenon might be explained by a failure of the myofibrils to increase the Ca2+ sensitivity after an increase of the sarcomere length.

Calcium↗
PubMed1994

[Injuries of the dens axis in childhood. Biomechanical analysis and surgical and conservative treatment of 2 cases].

Odontoid "fractures" in children are in fact typical lesions of the cartilaginous plate ("synchondrosis") separating the odontoid process from the body of the axis, 54 cases of which have been described in the literature so far. In our review we report about two 2-year-old children who were back-seat passengers restrained by four-point children's seat belts, in a car involved in a head-on motor vehicle accident. According to the accident research unit of our institution, trauma sustained in such circumstances is adequate for the causation of odontoid lesions in healthy children. Head-on collisions at a speed absorption of at least 40 km/h is described as a typical mechanism of such injury. Both children were immediately symptomatic, and the diagnosis was easily made from the X-rays. Neither child had neurologic deficits, which is in keeping with the literature, where neurologic injuries were found to have been reported exclusively in conjunction with head injuries. After closed reduction, conservative treatment was initiated in one child, in whom the extent of the anterior dislocation was smaller than the diameter of the odontoid shaft. In cases of major dislocation and more pronounced instability we recommend primarily open reduction and osteosynthesis with adequate implants. Our second case was treated with a halo fixator and a plaster vest for 12 weeks, but despite anatomic reduction there was no healing of the odontoid process. After temporary posterior fusion of C1/C2 we reamed the synchondrosis from an anterior approach and performed autogenous bone grafting. The posterior cerclage wire was removed after 5 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Accidents, Traffic↗
PubMed1994

[Liver complications of HELLP syndrome--an indication for emergency liver transplantation?].

Three patients were treated suffering from a severe HELLP-syndrome. The problems as far as the diagnostic and therapy are concerned are discussed. All three patients had to be operated on in an emergency state. The operations were performed due to acute and severe abdominal bleeding. Two of the patients needed liver transplantation as an emergency procedure, one of them died after hepatectomy waiting for a graft. Another one died seven weeks after successful transplantation due to prolonged sepsis. The third patient is more than one year after transplantation alive and doing well.

Adult↗
PubMed1994

Sensitization of adenylate cyclase by halothane in human myocardium and S49 lymphoma wild-type and cyc- cells: evidence for inactivation of the inhibitory G protein Gi alpha.

Halothane has been reported to sensitize the myocardium towards the effects of exogenous catecholamines in patients and laboratory animals. This study was aimed at investigating the catecholamine-sensitizing effects of halothane as well as the underlying subcellular mechanisms in human myocardium. Halothane augmented the positive inotropic effect of isoprenaline but not of Ca2+. The increase of the effect of isoprenaline by halothane was more pronounced in failing myocardium, with increased Gi, than in nonfailing donor hearts. Halothane (1%) increased basal as well as isoprenaline-, NaF-, cholera toxin-, and guanylylimidodiphosphate [Gpp(NH)p]-stimulated adenylate cyclase in human myocardial membranes (p < 0.05). Treatment of membranes with pertussis toxin increased adenylate cyclase by 40% and abolished the effect of halothane. Halothane had no effect on forskolin-stimulated adenylate cyclase. The same results, i.e., a pertussis toxin-sensitive increase of adenylate cyclase stimulation by halothane, were obtained in S49 cyc-, wild-type, or recombinant Gs alpha-reconstituted cyc- cell membranes. Carbachol-stimulated guanosine-5'-O-(3-[35S]thio)triphosphate binding was not influenced by halothane, but halothane attenuated the inhibition of adenylate cyclase by Gpp(NH)p in S49 cyc- cells. These data show that halothane stimulates adenylate cyclase and sensitizes adenylate cyclase after stimulation by beta-adrenoceptor agonists and guanine nucleotides due to an impairment of Gi alpha function. This mechanism may play a role in the halothane sensitization of myocardial adenylate cyclase towards catecholamines.

Adenylyl Cyclases↗
PubMed1994

[Value of computerized tomography in diagnosis of small intestine injuries after blunt abdominal trauma].

Intestinal injury is increasing in frequency among persons sustaining blunt abdominal trauma, and the consequences of delayed recognition of intestinal injuries are serious. This critical retrospective analysis evaluates the role for CT in the diagnosis of blunt abdominal trauma, including hollow visceral injury. CT scan, when used in conjunction with a history emphasizing the mechanism of injury and a careful physical examination, is highly accurate in detecting small bowel injuries. CT is less helpful in distinguishing between different types of small bowel injury. Intestinal wall thickening with low-density fluid in the abdominal cavity strongly suggests rupture. Until further experience is gained with CT, free intraperitoneal fluid in the absence of solid organ injury should be regarded as an indication for exploratory laparotomy.

Abdominal Injuries↗
PubMed1993

Subchronic toxicity of 2,3,7,8-tetrabromodibenzo-p-dioxin in rats.

2,3,7,8-Tetrabromodibenzo-p-dioxin (2,3,7,8-TBDD) was administered daily to male and female rats for 91 days by gavage. Ten male and 10 female rats per group received 0.01, 0.1, 1, 3, or 10 micrograms 2,3,7,8-TBDD/kg body weight per dose per day, solubilised in arachis oil. At 1 microgram/kg per day and above, body weight gain was dose-dependently reduced by treatment. Animals in the 3 and 10 micrograms/kg dose groups showed symptoms of wasting syndrome. Fifty percent of the animals in the 3 micrograms/kg dose-group died and all animals of the highest dose (10 micrograms/kg) died or had to be killed in extremis. Hematological investigations indicated changes--mainly in the 1 and 3 micrograms/kg dose-groups--in hemoglobin content, packed cell volume and number of thrombocytes. The prothrombin-time was markedly prolonged after 3 micrograms/kg in week 13. Clinical chemistry performed at the end of treatment revealed an increase in plasma alkaline phosphatase (APh), aspartate aminotransferase, ASAT and alanine aminotransferase, ALAT (females only) in the highest surviving dose-group (3 micrograms/kg). Marginal changes of APh and ASAT were seen in rats in the 1 microgram/kg dose-group. In the same animals, total bilirubin was elevated. Triglycerides were reduced mainly at 1 and 3 micrograms/kg. Serum thyroxin was reduced, beginning with a marginal change at 0.1 micrograms/kg, triiodothyronine was elevated, starting with a dose of 1 microgram/kg. Thymus weights were reduced in rats of the 1, 3 and 10 micrograms/kg dose-groups. Histopathological analysis showed atrophy of the lymphatic tissue in thymus and spleen. Investigations of the liver indicated peliosis hepatis after treatment with 3 or 10 micrograms/kg. Activities of microsomal enzymes (ethoxyresorufin O-deethylase, ethoxycoumarin O-deethylase, aryl hydrocarbon hydroxylase, UDP-glucuronyltransferase) investigated in liver, lung and kidney were dose-dependently elevated after 13 weeks of treatment. At a dose of 3.0 micrograms/kg, activities were below those of the dose 1.0 microgram/kg, probably due to liver toxicity. The induction ratio of kidney was generally higher than in liver and lung. No signs of treatment-related toxicity were observed in the 0.01 and 0.1 micrograms/kg groups after the subchronic administration of 2,3,7,8-TBDD by gavage.

Adipose Tissue↗