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Biomedical subjects

F Schmidt

Publications and source records attributed to F Schmidt.

At least 127 records · Page 7Linked to original sources
PubMed1995

An examination of the dental state of an Egyptian mummy by means of computer tomography: a contribution to 'dentistry in Ancient Egypt'.

In 1991 mummies from Leipzig collections were investigated by means of conventional X-ray techniques and by computer tomography. The dental state of one of these mummies prompted a re-examination of the question of whether a dental profession actually existed in Ancient Egypt or not. To answer this question, different types of source material are discussed.

Egypt, Ancient↗
PubMed1994

Opposite directed currents induced by the transport of dibasic and neutral amino acids in Xenopus oocytes expressing the protein rBAT.

Voltage- and current-clamp studies have been performed on a renal and intestinal protein (rBAT) which induces transport for neutral and dibasic amino acids when expressed in Xenopus oocytes. In current-clamp mode, superfusion with L-leucine caused a hyperpolarization while superfusion with L-arginine depolarized the oocyte. Accordingly, in voltage-clamp experiments dibasic amino acids and neutral amino acids induced inward and outward currents, respectively. The relationship between currents and substrate concentrations could be fitted by simple Michaelis-Menten kinetics. Currents induced by L-arginine and L-leucine were also voltage-dependent. pH changes from 6.25 to 8.75 did not affect the currents induced by saturating concentrations of L-arginine and L-leucine, but reversed the direction of L-histidine-induced currents from inward to outward. The reversal potentials as well as the apparent Km for L-histidine-induced currents were altered by the ambient pH. Currents induced by individual amino acids decreased during extended superfusion periods. However, extended superfusion with neutral amino acids increased dibasic amino acid induced currents, while prior superfusion with dibasic amino acid resulted in an increase of currents induced by neutral amino acids. The reversal potentials for L-leucine- and L-arginine-induced currents were depending on their intra- (after preloading) and extracellular concentrations. In conclusion, rBAT-mediated transport of neutral and dibasic amino acids is associated with net outward or inward currents, respectively, which may be caused by an exchange of neutral with dibasic amino acids.

Amino Acid Transport Systems, Basic↗
PubMed1994

Positive regulation by chloride channel blockers of IsK channels expressed in Xenopus oocytes.

cRNA encoding the human IsK protein was injected into Xenopus oocytes and the induced IsK channels were investigated using the two-microelectrode voltage-clamp method. Niflumic acid, mefenamic acid, flufenamic acid, and 4,4'-diisothiocyanatostilbene-2,2'- disulfonic acid, which are commonly used in Xenopus oocytes to suppress endogenous Ca(2+)-activated Cl- channels, were tested for their effects on IsK channels. At low concentrations (10 microM) all compounds increased IsK amplitude and decreased the rate of IsK deactivation. At 100 microM these compounds further decreased the rate of IsK deactivation, resulting in persistent activation of IsK, similar to what has been previously described for the action of organic cross-linkers on IsK. However, at 100 microM niflumic acid and flufenamic acid decreased the time-dependent outward current, whereas 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid and mefenamic acid caused an additional increase. When Cl- was completely substituted with gluconate, IsK had somewhat altered activation properties, but niflumic acid produced similar positive regulatory effects on IsK and shifted the voltage needed to evoke half-maximal IsK activation (V1/2) by about -20 mV. In summary, these compounds positively regulate IsK, presumably by stabilizing open IsK channels.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1993

Relation of elastosis to biochemical and immunohistochemical steroid receptor findings, Ki-67 and epidermal growth factor receptor (EGFR) immunostaining in invasive ductal breast cancer.

We studied 1073 cases of invasive ductal breast cancer, NOS for their elastic content (DEL, ductal+periductal elastosis; TEL, tumour elastosis) and compared the findings with the results of biochemical and immunohistochemical steroid hormone receptor examination. Tumours of patients up to 50 years of age and older were examined separately. In a number of tumours elastosis was also examined in relation to Ki-67 and epidermal growth factor receptor (EGFR) immunostaining. Sensitivity and specificity of DEL and TEL for predicting the receptor, Ki-67 and EGFR findings were estimated. Sensitivity of DEL and TEL for oestrogen and progesterone receptors is dependent on the degree of tumour differentiation and the degree of elastosis, increasing from DEL 1 degree and TEL 1 degree to DEL 3 degrees and TEL 3 degrees. It was more evident in grade 1 (G1) and G2 than in G3 carcinomas. Elastosis is a useful predictor of positive receptor findings particularly in G1 and G2 tumours with moderate and high-grade elastosis. It is a similarly useful predictor of negative receptor values in G3 carcinomas. The predictive value of DEL and TEL for the results of Ki-67 and EGFR immunostaining gradually decreases with increasing elastosis, consistent with the assumption that Ki-67 and EGFR identify the degree of tumour proliferation and invasion, while elastosis correlates with the degree of differentiation of breast cancer. Elastosis is a poor predictor of Ki-67 and EGFR findings in any individual breast cancer. Moderate and high-grade elastosis points to positive steroid hormone receptor assays in G1 and G2 carcinomas. In contrast, the lack of elastosis in G3 carcinomas may indicate a negative receptor assay. Both findings have a high degree of reliability.

Breast Neoplasms↗
PubMed1991

[Cefmenoxime penetration in human lacrimal sac mucosa after systemic administration].

Access to microbiological, pharmacokinetic and toxicological information is necessary for useful, controlled application of antibiotics in intraocular and periocular infections. It is important to know whether the antibiotic is effective against ophthalmologically relevant bacteria and if suprathreshold concentrations of the antibiotic can be achieved in the contaminated tissue. In the study presented we investigated the usefulness of cefmenoxime in cases of dacryocystitis. Lacrimal sac tissue--and serum specimens were obtained from 15 patients who underwent dacryocystorhinostomy 0.5 to 13 h after intravenous injection of 25 mg cefmenoxime kg. The usual Toti procedure was performed in 7 patients, whereas the other 8 underwent endonasal surgery. Out of the 15 patients 12 suffered from recurrent dacryocystitis. Before application of the antibiotic a serum control sample was obtained in all patients. The highest cefmenoxime levels in the lacrimal sac (72 mg/kg) were measured 30 min after injection. Thirteen hours after the injection, the cefmenoxime levels were too low to be measured. The levels of cefmenoxime in the lacrimal sac tissue were compared with the minimal inhibitory concentrations for the frequent occurrence of bacteria in lacrimal sac infections.

Adolescent↗
PubMed1991

[Diagnostic value of the routine thoracic image].

A considerable part of the amount of diagnostic medical radiation exposure to the population in the industrial nations is due to chest x-rays. We correlated diagnostic gain and medical indication for the screening procedure in 1000 patients referred. In fact, in only 270 patients a specific indication was given, and in only 136 cases were there pathologic findings. Our results suggest a more restrictive policy in indicating the procedure. We give proposals for optimization.

Aged↗
PubMed1990

Electrophysiologic effects and efficacy of cibenzoline on stimulation-induced atrial fibrillation and flutter and implications for treatment of paroxysmal atrial fibrillation.

The effects of intravenous cibenzoline (1.5 mg/kg) on atrial vulnerability and electrophysiology were assessed in 25 patients with documented paroxysmal atrial fibrillation (AF), in whom sustained (greater than 30 seconds) AF was induced by atrial stimulation with up to 2 extrastimuli and paced rates between 100 and 180 beats/min. In 7 patients AF persisted despite the application of cibenzoline, and in 8 patients the induction of sustained AF was prevented by cibenzoline. Intraatrial conduction time, flutter cycle length and shortest ventricular cycle length during AF were increased by cibenzoline (p less than or equal to 0.01). Sinus cycle length was decreased (p less than or equal to 0.05), whereas sinus node recovery time remained unchanged. The effective refractory period of the right atrium was not significantly affected. Eight patients with frequent episodes of paroxysmal AF received oral cibenzoline for control of paroxysmal AF irrespective of the efficacy of intravenous cibenzoline. Prevention of stimulation-induced AF predicted successful treatment of paroxysmal AF (p = 0.018). Cibenzoline could be effective in the treatment of atrial arrhythmias, and selection of an antiarrhythmic therapy for recurrent AF seems to be useful.

Administration, Oral↗
PubMed1990

Oxidation of the indole nucleus of 5-hydroxytryptamine and formation of dimers in the presence of peroxidase and H2O2.

5-Hydroxytryptamine (5-HT) is rapidly oxidized in the presence of peroxidase and H2O2. The major reaction product was isolated by gel chromatography and analyzed by mass spectroscopy. It is a 5-HT dimer formed under abstraction of two protons, most likely by the reaction at the C(4) position of two phenoxyradicals of 5-HT. In the presence of 5-HT an increased H2O2-consumption and a dose dependent reduction of the formation of reactive oxygen metabolites during H2O2 degradation was observed. The pattern of 5-HT reaction products separated by TLC was dependent on the H2O2 concentrations used. In the presence of albumen, plasma or tissue homogenates, massive binding of the 5-HT oxidation products to proteins was observed.

Albumins↗
PubMed1990

[Research schools in pharmacy. 5: Alexander Tschirch (1856-1939) and his students].

Alexander Tschirch was one of the most important teachers of pharmacy. In 1890 he was appointed Professor of Pharmacy and Pharmacognosy at Bern and he was a good director of his institute. The scientific programme is represented by 21 books, 388 papers and 158 dissertations. The main topics were investigations of plants (phytochemical) and researchs for pharmacopoeias. Tschirch had 2300 Students, 158 made their doctor-graduate and 11 are becoming professor. The research conditions in the pharmaceutical institute Bern were good and the research school of Tschirch has an important public and social recognition, also Tschirchs work provided the bases of the modern phytochemical research of plants.

History of Pharmacy↗
PubMed1989

[Diagnostic imaging of pancreatic cancer].

Despite the multitude of the imaging procedures which are nowadays at our disposal the diagnostics of the carcinoma of the pancreas and particularly of the early carcinoma is now as ever difficult. On the basis of a multicentric team study about the diagnostic course in 62 patients with diagnosed carcinoma of the pancreas we conclude to an effective diagnostic proceeding. Hereby a broad use of the ultrasound diagnostics is to be demanded and the bioptic clarification of focal findings is early to be carried out. With the help of the serial CT the differentiation between chronic pancreatitis and carcinoma of the pancreas finds particular consideration, it was successful with a reliability of 84%.

Biopsy, Needle↗
PubMed1989

Further evidence for a two-step model of glucose-transport regulation. Inositol phosphate-oligosaccharides regulate glucose-carrier activity.

The insulin effect on glucose uptake is not sufficiently explained by a simple glucose-carrier translocation model. Recent studies rather suggest a two-step model of carrier translocation and carrier activation. We used several pharmacological tools to characterize the proposed model further. We found that inositol phosphate (IP)-oligosaccharides isolated from the drug Actovegin, as well as the alkaloid vinblastine, show a partial insulin-like effect on glucose-transport activity of fat-cells (3-O-methylglucose uptake, expressed as % of equilibrium value per 4 s: basal 5.8%, insulin 59%, IP-oligosaccharides 30%, vinblastine 29%) without inducing carrier translocation. On the other hand, two newly developed anti-diabetic compounds (alpha-activated carbonic acids, BM 130795 and BM 13907) induced carrier translocation to the same extent as insulin and phorbol esters [cytochalasin-B-binding sites in plasma membranes: basal 5 pmol/mg of protein, insulin 13 pmol/mg of protein, TPA (12-O-tetradecanoylphorbol 13-acetate) 11.8 pmol/mg of protein, BM 130795 10.8 pmol/mg of protein], but produce also only 40-50% of the insulin effect on glucose-transport activity (basal 5.8%, insulin 59%, TPA 23%, BM 130795 35%). Almost the full insulin effect was mimicked by a combination of phorbol esters and IP-oligosaccharides (basal 7%, insulin 50%, IP-oligosaccharides 30%, TPA 23%, IP-oligosaccharides + TPA 45%). None of these substances stimulated insulin-receptor kinase in vitro or in vivo, suggesting a post-kinase site of action. The data confirm the following aspects of the proposed model: (1) carrier translocation and carrier activation are two independently regulated processes; (2) the full insulin effect is mimicked only by a simultaneous stimulation of carrier translocation and intrinsic carrier activity, suggesting that insulin acts through a synergism of both mechanisms; (3) IP-oligosaccharides might be involved in the transmission of a stimulatory signal on carrier activity.

3-O-Methylglucose↗