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Biomedical subjects

G Schmidt

Publications and source records attributed to G Schmidt.

At least 397 records · Page 22Linked to original sources
PubMed1986

Inhibitory effect of nifedipine on cholecystokinin-induced gallbladder contraction in man.

A prospective study was performed on seven male and eight female patients with normal hepatobiliary findings to investigate the effect of 20 mg nifedipine on cholecystokinin-induced gallbladder contraction. Each patient received 1 IDU (Ivy dog unit) cholecystokinin per kg body weight intravenously on two consecutive days, with additional administration of 20 mg nifedipine sublingually on the second day. Gallbladder volumes were assessed by ultrasonography over a period of 25 minutes. Cholecystokinin induced a maximal reduction in the mean initial volume of 56.8 +/- 3.6%. After nifedipine, this volume change was significantly reduced to 30.9 +/- 5.1% (p less than 0.001). Thus our data suggest for the first time that the calcium-channel-blocking agent nifedipine can have an effect on human gallbladder kinetics.

Adult↗
PubMed1985

Small-angle neutron scattering study of lateral phase separation in dimyristoylphosphatidylcholine-cholesterol mixed membranes.

The small-angle neutron scattering (SANS) technique developed previously is used to study the lateral phase separation in dimyristoylphosphatidylcholine (DMPC)-cholesterol mixed vesicles in the L alpha (35 degrees C) and L beta' (7 degrees C) phase of DMPC. To increase the sensitivity of the previous method, we apply the so-called inverse contrast variation technique where contrast matching is performed at a constant H2O/D2O ratio by varying the ratio of DMPC with deuterated and protonated hydrocarbon chains. Phase boundaries can be determined to an accuracy of +/- 0.5 mol %. In parallel experiments phase separation in the L beta' phase was also studied by freeze-fracture electron microscopy. For DMPC in the L alpha phase complete miscibility is clearly established up to cholesterol molar fractions of xc = 0.14. Strong evidence is provided that this is also the case up to xc approximately equal to 0.45. Cholesterol is no longer soluble above this limit and precipitates as small crystallites. For the L beta' phase (7 degrees C) phase boundaries are clearly established at xc1 = 0.08 and xc2 = 0.24, and very strong evidence is provided for two additional boundaries at xc3 = 0.435 and xc4 approximately equal to 1.0. At 0 less than or equal to xc less than or equal to xc1 the mixture forms a tilted solid solution in both the L beta' and P beta' phase while at xc1 less than or equal to xc less than or equal to xc2 this phase coexists with a nontilted mixture containing 24 mol % cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS)

Cholesterol↗
PubMed1985

Effects of tolbutamide on blood flow in islets and exocrine tissue of the rat pancreas.

The influence of tolbutamide (20 mg/kg and 100 mg/kg i.v.) on blood flow to the entire pancreatic gland and to its endocrine tissue was studied in anaesthetized rats. Non-radioactive microspheres 8.8 micron diameter were used for determination of local blood flow rates. The islet tissue was subsequently stained intravitally with dithizone. The organ was subdivided into small samples, frozen and thawed then scanned in the microscope for spheres in endocrine and exocrine tissue, respectively. Tolbutamide only insignificantly affected total organ blood flow (0.53 ml X min-1 X g-1, controls; 0.61 ml X min-1 X g-1 lower dose; 0.39 ml X min-1 X g-1 higher dose) but significantly increased the percent islet perfusion (3.0% controls; 6.6% lower dose; 10.5% higher dose of tolbutamide). The results favour the view that these vascular effects might facilitate insulin release into the systemic circulation.

Animals↗
PubMed1985

Ca2+-induced phase separation in black lipid membranes and its effect on the transport of a hydrophobic ion.

Voltage jump-current relaxation studies have been performed with dipicrylamine-doped black membranes of binary lipid mixtures. As in the case of the carrier-mediated ion transport (Schmidt, G., Eibl, H. and Knoll, W. (1982) J. Membrane Biol. 70, 147-155) no evidence was found that the neutral lipid phosphatidylcholine (DPMPC) and the charged phosphatidic acid (DPMPA) are heterogeneously distributed in the membrane over the whole range of composition. However, besides a continuous dilution of the surface charges of DPMPA by the addition of DPMPC molecules, different structural properties of mixed membranes influence the kinetics of the dipicrylamine transport. The addition of Ca2+ to the electrolyte induces a lipid phase separation within the membrane into two fluid phases of distinctly different characteristics of the translocation of hydrophobic ions. Thus, it is possible to determine a preliminary composition phase diagram for the DPMPA/DPMPC mixtures as a function of the Ca2+ concentration.

Adsorption↗
PubMed1985

Increased excretion of harman by alcoholics depends on events of their life history and the state of the liver.

Based on the hypothesis of a relationship between the concentration of trace amines like tetrahydroisoquinolines (TIQ's) and beta-carbolines (BC's) in the brain and an increased voluntary ingestion of ethanol, the concentrations of ethanol, acetaldehyde and harman (a beta-carboline) were examined in a group of 20 alcoholics. The patients excreted a higher amount of harman into the urine than non-alcoholics on the day of admission (harman-1) as well as at the end of the detoxication period, 14 days later (harman-14). Certain factors were related to the increased excretion of harman by alcoholics: The younger the patient when he/she consumed ethanol for the first time, the higher the concentration of acetaldehyde in the blood and the amount of harman (harman-14) excreted in the urine. Furthermore, the younger the patient when he/she was intoxicated with ethanol for the first time the higher the amount of harman (harman-14) in the urine. Patients with first grade relatives who were alcoholics excreted more harman (harman-14) than those without such relatives. The following variables were not related to harman-14: The average amount of ethanol consumed daily during the 6 months prior to admission, the presence of signs of intoxication and symptoms of withdrawal at admission to hospital, and the consumption of other psychotropic substances. A negative correlation was found between the state of the liver, as assessed by liver histology and gamma-glutamate transferase (gamma-GT) levels, and the concentration of harman in the urine. Thus, some events in the patient's history as well as the state of the liver are important for the increased excretion of harman into urine of alcoholics.

Acetaldehyde↗
PubMed1985

Occlusion of inner ear vessels by magnetic forces applied to circulating metallic iron particles.

We describe a method for the photometric assay of the content of carbonyl iron powder in the blood and discuss a process comparing the in vitro effects of bar magnets on flowing carbonyl iron powder suspensions. We have used this method experimentally on laboratory animals and have induced thrombosis of inner ear vessels with magnetic forces following injections of the carbonyl iron powder.

Animals↗
PubMed1985

Acute effects of antiarrhythmic drugs on stable ventricular premature beats. Controlled comparison of lorcainide and lidocaine.

Nineteen patients with refractory but stable ventricular premature beats (VPB) received 3 medications intravenously at 24-h intervals. Lorcainide (2 mg/kg) and placebo were given double-blind in randomized sequence and the third treatment was 100 mg lidocaine, the standard reference drug. Continuous ECG recordings were made for the first 2 hours after administration to study the antiarrhythmic effect; the stability of the arrhythmia, the absence of residual and of period effects, and the interdrug differences in efficacy were statistically evaluated. Lorcainide significantly reduced the frequency of VPB during the 2-hour period, whereas the effect of lidocaine was more short-lived. The median individual peak reduction in VPB was 96% for lorcainide and 47% for lidocaine. No significant reduction in VPB was observed with placebo. Adverse effects were acceptable with either active treatment.

Adult↗
PubMed1985

Endoscopy of the terminal ileum. Diagnostic yield in 400 consecutive examinations.

A prospective study was undertaken to investigate the feasibility and diagnostic yield of ileoscopy as an extension of total colonoscopy. The distal 15 to 40 cm of the terminal ileum were visualized in 400 of 555 consecutive patients submitted to total colonoscopy (72 percent). Intubation of the terminal ileum was not successful in 42 patients (8 percent), not tried in 63 (11 percent), and hampered by inadequate colonic cleansing in 50 (9 percent). We observed 13 patients with terminal ileitis and seven rare findings such as nonspecific ileal ulcer or non-Meckelian diverticulum, etc., adding to a total of 20 pathologic findings in 400 examinations (5 percent). In a further group of 98 patients, useful diagnostic information was gained by the demonstration of normal ileal findings, making ileoscopy clinically valuable in 118 of 400 examinations (29.5 percent) in this series. We suggest routine endoscopy of the terminal ileum in all patients with suspected or established inflammatory bowel disease and/or persistent diarrhea, lower gastrointestinal tract bleeding, or irritable bowel syndrome, in whom the diagnostic procedure includes colonoscopy. In patients with colorectal tumors or polyps, the diagnostic yield will be unrewarding.

Adolescent↗
PubMed1985

What's new in steroid and nonsteroid drug effects on gastroduodenal mucosa?

A survey is given on the damaging effect of acetylsalicylic acid, other nonsteroidal antiinflammatory drugs and corticosteroids on the gastroduodenal mucosa. The results of blood loss studies and endoscopic investigations are reviewed. Also, the histologic aspects of such damage are discussed. Modern concepts of the pathophysiology of these lesions stress the cytoprotective role of endogenous prostaglandins. Epidemiologic data strongly support an association between frequent and heavy intake of acetylsalicylic acid and gastric ulcer as well as gastrointestinal bleeding, whereas the association with duodenal ulcers is far less clearly established. Conclusive evidence is currently unavailable proving the superiority of other nonsteroidal antiinflammatory drugs in this regard. The ulcerogenic potency of corticosteroids at least in the small or medium dose range probably has been overstated in the past. Intensive ulcer therapy making use of H2 receptor antagonists often allows healing of small ulcers with a diameter up to 1 cm despite continued treatment with low dose corticosteroids or nonsteroidal antiinflammatory drugs, whereas continuation of these drugs is associated with very poor healing in ulcers larger than this size. The danger of perforation has to be taken into consideration.

Adrenal Cortex Hormones↗
PubMed1985

Interactions between progestins and estradiol on serum lipids in the rat.

In female rats the influence of progestins of the estrane type [norethisterone acetate (NEA), norgestrel (NG) and dienogest (DEG)] and of the pregnane type [chlormadinone acetate (CMA), progesterone (P)] on total cholesterol (TC) and high-density-lipoprotein cholesterol (HDL-C) in serum has been investigated in combination with estradiol (E). E increased TC (45%) and HDL-C (12%). NEA, NG and DEG alone decreased TC maximally by 58% and HDL-C maximally by 67%, CMA and P were without influence. In combination with E, the gestagens NEA, NG and DEG suppressed the E-induced increase of TC and HDL-C, whereas CMA and P did not counteract the TC increase. The effects of estrogen/gestagen combinations on HDL-C in the serum of rats are similar to those in men, but species differences in the lipoprotein metabolism must be taken into consideration.

Animals↗
PubMed1985

[Initial experiences with MR in liver tumors].

We examined 21 patients with focal lesions of the liver. Routinely we used T1 weighted, proton weighted and T2 weighted measurement modes, mainly with repetition times of 1.6 sec and echo delay times of 35 or 120 msec. Using these parameters we can see characteristic changes of the signals of the liver tumours. Cystic lesions usually show a strong decrease of the signal in the T1 weighted images in comparison with the normal liver pattern, in the proton weighted images a weak decrease but also in some cases a weak increase of the signal; in the T2 weighted images they show signals of very great intensity. We can differentiate haemangioma of cystic lesions because of the very strong signal in the proton weighted images in comparison with the normal liver pattern, which we could not see in any other focal liver disease. Metastases and hepatoma produced low signal intensity in the T1 weighted image. The proton weighted and the T2 weighted images show signals with a slightly greater intensity compared with the normal pattern, i.e. a very good possibility to distinguish hepatoma and metastases from cystic lesions or haemangioma. The differentiation from hepatoma and metastases cannot be made with NMR up to now. We are also not able to differentiate the focal nodular hyperplasia (FNH) from metastases. We used a 0.35 T supraconductive magnetic system.

Cysts↗