PubMed Health⌕ Search

Biomedical subjects

W Hartmann

Publications and source records attributed to W Hartmann.

At least 73 records · Page 4Linked to original sources
PubMed1982

Protein-catalyzed phospholipid exchange in bilayer vesicles determined by flow cytometry and electron microscopy.

The protein-induced lipid transfer between phosphatidylcholine vesicles was investigated. Measurements of the degree of polarization at single vesicles were made by flow cytometry using diphenylhexatriene as the optical probe. Vesicles differing in phase transition temperature could be distinguished by their degree of polarization at a temperature where one population was in the fluid (T greater than Tt) and the other one in the quasi-crystalline (T less than Tt) state. Besides vesicles containing exchange lipids we also observed fractions of unaffected vesicles. The lipid exchange was visualized directly by freeze-fracture electron microscopy. The characteristic 'ripple' structure of phosphatidylcholine vesicles disappeared upon exchange with lipid in the fluid state.

Carrier Proteins↗
PubMed1982

[Principles for the evaluation and differentiation of single protein findings in the cerebrospinal fluid with the examples of IgG, IgA, IgM and transferrin].

Valuation methods for IgG, IgA, IgM and transferrin in normal and pathologically abnormal CSF samples are described. All proteins were determined by a modified electro-immuno-precipitation technique on cellulose acetate films in CSF which had not been concentrated. The methods for valuating IgG, IgA and transferrin were derived from criteria for the relation between each of the different proteins and the total protein concentration of normal CSF samples. Due to the limits of detection with our equipment, a different evaluation scheme was used for IgM. This was based on the changes in IgM concentration in the CSF which had a total protein content between 500 and 2.500 mg/1. These methods of valuation can be used to interpret changes in the mechanisms of the cerebral barrier function and/or the immunological status of neuropsychiatric diseases.

Blood-Brain Barrier↗
PubMed1981

Effects of truncal vagotomy and antrectomy on bombesin-stimulated pancreatic secretion, release of gastrin, and pancreatic polypeptide in the anesthetized dog.

The short-term effects of truncal vagotomy and antrectomy on bombesin-stimulated pancreatic secretion and release of gastrin and pancreatic polypeptide (PP) were studied in 18 anesthetized dogs. Together with an intravenous infusion of secretin (250 ng/kg/hr) bombesin (500 ng/kg/hr) was given before and after truncal vagotomy, antrectomy, and sham operation (N = 6 dogs per group). Peak incremental pancreatic protein output in response to bombesin was about 2-3 times higher before than after the different surgical procedures (tachyphylaxis). Neither truncal vagotomy nor antrectomy significantly altered the pancreatic protein response to bombesin when compared with sham operation. Bombesin produced a mean 1-hr increase over basal of 196 pM for gastrin, which was abolished by antrectomy but not appreciably affected by truncal vagotomy and sham operation. The mean 1-hr increment (207 pM) for PP in response to bombesin was not changed by truncal vagotomy, antrectomy, and sham operation. This study shows in the anesthetized dog that exogenous bombesin stimulates release of PP as well as gastrin; that the release of gastrin by bombesin is not vagally dependent; that neither truncal vagotomy nor antrectomy alter the release of PP by bombesin; and that the action of bombesin on pancreatic protein secretion does not depend on release of gastrin or on intact vagal nerves.

Animals↗
PubMed1981

[Cooperation of engineers and physicians in accident prevention].

Technical protection represents one of several conditions which are necessary to protect the health of working people. As men are themselves part of technical systems, an integrated approach of safety and health protection is needed. The task is not only interdisciplinary but also transdisciplinary. Safety efforts have to take into account the three elements hardware, procedures and people as well as the three interfaces between these elements. The cooperation between engineers and medical doctors on workplace inspections, on accident investigations and on reintegration of injured workers are described.

Accidents, Occupational↗
PubMed1981

[Intra-abdominal melanoma metastases and their prognosis].

Very often in advanced stages of malignant melanoma several organs are involved. In a small number of patients only intraabdominal metastases seem to occur. The analysis of 106 cases found in the literature and 6 cases from our department revealed the small bowel and the stomach as the main site of metastases, giving rise to intestinal bleeding and obstruction. Apart from emergency cases, even in the advanced stage of disease palliative procedures are indicated since the prognosis in individual cases is quite unpredictable, as seen in some cases with a survival time of up to seven years.

Abdominal Neoplasms↗
PubMed1981

[The frequency of gallstones in liver cirrhosis (author's transl)].

Out of 11 840 autopsies from 1940-1975 697 cases with cirrhosis of the liver were found. The percentages of gallstone disease in these cases was analyzed as compared to non - cirrhotic controls. 21,5% of cirrhotic patients had cholelithiasis versus 16,5% in the controls (p less than 0,001). In women 35,2% of cirrhotics versus 26,3% (p less than 0,01) and in men 16,2% versus 10,8% (p less than 0,001) were found with gallstones. Including cases with cholecystectomies the frequencies was 22,8% for cirrhosis and 19,9% for controls (men 16,9% versus 12,9%, women 37,7% versus 33,6%). These differences were not significant. The female to male ratio for the frequency of cholelithiasis was found to be 2,2 : 1 and was not altered as compared to be controls. In cirrhotic and control patients the frequency of cholelithiasis increased steadily with each decade of age, again more in women than in men. A tendency to higher frequencies for gallstones in cirrhotic patients was found from the 5th decade onwards, but this was not statistically significant.

Adult↗
PubMed1981

[Joint hospitalisation of mentally ill mothers and their children (author's transl)].

Joint admission of mothers with puerperal psychoses and their babies to the psychiatric hospital has proved successful. This not only avoids possible damage to the child and to the mother-child relationship as a result of prolonged separation; it appears that in fact the mother herself recovers more rapidly and is more self-assured in managing the child after her discharge from hospital. This, in turn, reduces the danger of a relapse and helps to stabilize the mother-child relationship. Joint admission of mother and infant is advisable whenever the neurotic signs shown by the mother centre around the relation to her baby. Joint admission is usually technically easy, while making exacting demands on the nursing staff. It requires detailed planning and organisation coupled with continual and close supervision. Under these conditions, joint hospitalisation of mother and child represents a widening of our therapeutic possibilities.

Adult↗
PubMed1980

Excimer-forming lipids in membrane research.

Pyrenedecanoic acid and pyrene lecithin are optical probes well suited to investigate lipid bilayer membranes. The method is based on the determination of the formation of excited dimers or excimers. The rate of excimer formation yields information on the dynamic molecular properties of artificial as well as of natural membranes. This article will review applications of the excimer-forming probes. Pyrene lipid probes are used to determine the coefficient of the lateral diffusion in fluid lipid membranes. Results in artificial membranes are comparable to the values obtained in erythrocyte membranes. Moreover, the excimer formation rate is a very sensitive measure of changes in membrane fluidity. Membrane fluidity is an important regulator of membrane functional proteins. For example, there is a correlation between membrane fluidity and enzyme activities of the adenylate cyclase system. The excimer formation technique is not restricted to the measurement of lateral mobility in membranes. It can also be used to determine the transversal mobility, that is, the lipid exchange between the lipid layers of one bilayer or between bilayers of different vesicles. Again, artificial as well as natural membranes can be investigated by this technique. Another important area of investigation in membrane research is the interaction between lipids and proteins. Lipids, in the presence of a protein, show a different dynamic behavior from free lipids. Because of changes in fluidity and a modified solubility of the pyrene probes within different membrane regions, our methods could also be applied to the examination of phase separation phenomena and to lipid-protein interactions.

Cholesterol↗
PubMed1980

Immunoreactive secretin release following taurocholate perfusions of the cat duodenum.

Perfusion of the cat duodenum with sodium taurocholate (TC), 120 mmol/l, at pH 6.1 increased the plasma immunoreactive (IRS) concentration from 2.2 +/- 0.7 pmol/l to 29 +/- 6.1 pmol/l during the first 20 min. This was accompanied by an increased pancreatic secretion of fluid, while the chymotrypsin output showed a "wash-out' phenomenon. TC increased both the bile-acid-dependent and the bile-acid-independent bile secretion. In comparison, HCl, 150 mmol/l, increased IRS from 0.9 +/- 0.5 pmol/l to 41 +/- 15 pmol/l, producing an increase in the pancreatic fluid secretion. However, only a slight increase in the bile-acid-independent bile secretion was found, and the bile-acid-dependent secretion did not change. The effects of TC on the pancreatic secretion were produced at concentrations occurring in cat hepatic bile.

Animals↗
PubMed1980

Stimulation of bile and pancreatic secretion by duodenal perfusion with Na-taurocholate in the cat compared with jejunal and ileal perfusion.

In the anesthetized cat duodenal perfusion with Na-taurocholate (TC, 0.2 M, pH 6.1, 290 mosmol, 45 ml x h-1) stimulated pancreatic volume (0 to 326 +/- 236 mg x 10 min-1) and bicarbonate secretion (0 to 34.2 +/- 4.1 mumol x 10 min-1), whereas pancreatic enzyme output was sparse. Simultaneously with the pancreatic response, bile flow increased from 139 +/- 74 mg to 484 +/- 146 mg x 15 min-1 (p < 0.05). During perfusion of the upper jejunum both pancreatic and biliary responses were significantly lower than the responses to duodenal TC perfusion (p < 0.05). During TC perfusion of the terminal ileum there was no response from the pancreas, whereas the increase in bile flow accounted only for an increase in the bile-acid-dependent fraction. The concomitant stimulation of both the hydrokinetic function of the pancreas and the bile-acid-independent bile flow might be mediated by a release of secretin.

Animals↗
PubMed1980

Light and electron microscopy of human liver before and during chenodeoxycholic acid therapy.

Thirteen patients (9 women, 4 men) with solitary (7) or multiple (6) radiolucent gallstones were treated with 1.0 g/day CDCA over a period of 7--17 months (mean 10.2). Routine liver function tests showed no changes compared to pre-treatment values, except a moderate elevation of SGPT activity in one patient. Serum cholesterol and serum triglyceride levels remained unchanged during therapy. 21 liver biopsies in 11 patients compared to pre-treatment controls studied by light and electron microscopy revealed no lesions in hepatic structure, especially no signs of cholestasis. Only some unspecific changes in liver ultrastructure as shown during therapy with other drugs developed during CDCA treatment (lipofuscin depositions, swollen and condensed mitochondria and a dilated rough endoplasmic reticulum). It is, therefore, concluded that CDCA therapy for gallstone dissolution has no hepatotoxic side effects.

Adult↗
PubMed1980

Detection of lymphocyte stimulation by flow cytometry: differences in cells from patients with and without neoplasia.

Fluorescence polarization measurements were performed to detect PHA-stimulation of peripheral lymphocytes in an early state. Single cell fluorescence was measured by flow cytometry using an epi-illumination design to avoid the influence of background fluorescence and multiscattering. By these arrangements the accuracy in the determination of P, the degree of polarization, could be improved over the usual cell suspension measurements. Fluorescence polarization measurements were performed on density specified human lymphocytes after incubation with fluorescein diacetate with and without preincubation with phytohemagglutinin (PHA). A group of healthy donors had an average polarization of P = 0.17 before and P = 0.12 after PHA-stimulation, whereas a group of patients with malignant disease showed an average polarization of P = 0.14 before and after PHA-stimulation.

Adult↗
PubMed1979

On two-dimensional passive random walk in lipid bilayers and fluid pathways in biomembranes.

The lateral mobility of pyrene, pyrene decanoic acid, and 1-palmitoyl-2-pyrene decanoyl-phosphatidyl choline (pyrene lecithin) in lipid bilayers is determined by the excimer formation technique. This method is applied to vesicles of lecithins differing in chain length and in the degree of saturation of the hydrocarbon chains. These values are compared with results in cephalins of different chain length and in dipalmitoyl phosphatidic acid at variable pH. The influence of cholesterol is investigated. The results are analyzed in terms of the Montroll model of two-dimensional random walk. The jump frequency of the probe molecule within the lipid lattice is obtained. The advantage of this measure of transport in lipid layers is that it does not involve lipid lattice parameters. The main results of the present work are: (i) The lateral mobility of a given solute molecule in lamellae of saturated lecithins is independent of hydrocarbon chain length and rather a universal function of temperature. (ii) In unsaturated dioleyl lecithin the amphiphatic molecules have lateral mobilities of the same size as in saturated lipids. The jump frequency of pyrene, however, is by a factor of two larger in the unsaturated lecithin. (iii) The jump frequencies in phosphatidyl ethanolamines are about equal to those in lecithins. (iv) In phosphatidic acid layers the hopping frequencies depend on the charges of the head groups of both the lipids and the probes. (v) Cholesterol strongly reduces the jump frequency in fluid layers. (vi) The lateral mobility in biological membranes is comparable to that in artificial lipid bilayers. The experimental results are discussed in terms of the free volume model of diffusion in fluids. Good agreement with the predictions made from this model is found. A striking result is the observation of a tilt in dioleyl-lecithin bilayer membranes from the hopping frequencies of pyrene and pyrene lecithin. A tilt angle of phi = 17 degrees is estimated.

Cholesterol↗