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Biomedical subjects

W Jung

Publications and source records attributed to W Jung.

At least 253 records · Page 14Linked to original sources
PubMed1982

Biliary secretion of sodium fluorescein in primary monolayer cultures of adult rat hepatocytes and its stimulation by nicotinamide.

Addition of sodium fluorescein to primary cultures of rat hepatocytes resulted in a rapid uptake of the dye by the hepatocytes and a subsequent accumulation in bile canaliculi-like structures. A similar distribution was obtained with fluorescein diacetate. Concentrations of Na-fluorescein accumulating within canaliculi varied over a wide range, often far exceeding that used in the medium. Ouabain strongly blocked cellular uptake, thus also impairing secretion of Na-fluorescein, whereas colchicine affected neither process. Taurolithocholate had virtually no influence on uptake, but markedly reduced the number of fluorescent canaliculi. Furthermore, fluorescent canaliculi could be discharged by addition of I M-sucrose in Hank's buffer, without affecting viability of the cultured cells. The percentage of canicular structures accumulating high amounts of Na-fluorescein markedly increased during cultivation for 7 days, concomitant with the progressive development of originally small and sporadic canaliculi into an anastomosing network of slender channels. This canalicular proliferation was strikingly reinforced by 20 mM-nicotinamide, resulting in an impressive network of canaliculi within 2-3 days. Nicotinamide also supported the secretion of Na-fluorescein, which could be stimulated further by addition of dehydrocholate. These results suggest that cultured hepatocytes are able to re-create a functional biliary polarity at least with respect to the biliary secretion of Na-fluorescein.

Animals↗
PubMed1982

Alterations in activity and ultrastructural localization of several phosphatases on the surface of adult rat hepatocytes in primary monolayer culture.

Several enzymes associated with the hepatocyte cell surface, alkaline phosphatase (AP), 5'-nucleotidase (5'N), Mg++- and total Na+K+Mg++-ATpase, were assayed and localized cytochemically in order to gain insight into alterations of the plasma membrane components during reassociation of hepatocytes in primary monolayer culture. During a period of 4 days the activities of 5'nucleotidase and alkaline phosphatase increased spontaneously up to three- and four-fold, respectively. Dexamethasone reinforce the rise of alkaline phosphatase activity but retarded the increase of that of 5'nucleotidase. However, after the third day the level of 5'nucleotidase activity converged with the untreated controls. The activities of Mg++- and Na+K+Mg++-ATPase, which closely paralleled each other, remained essentially unchanged throughout cultivation and were not affected by dexamethasone. Cytochemical demonstration of alkaline phosphatase, 5'nucleotidase and Mg++-ATPase, using the lead salt method, revealed the potential presence of reaction product on the whole cell surface. However, the cells did not react uniformly, particularly on bile canalicular membranes. This heterogeneity seems to be due to different stages of canalicular development and to different functional states of the cultured hepatocytes.

5'-Nucleotidase↗
PubMed1982

Influence of prostacyclin on regional blood flow distribution in anesthetized dogs.

Prostacyclin (PGI2), a major metabolite of arachidonic acid, is widely distributed throughout the cardiovascular system and may influence vascular smooth muscle tone. To evaluate the effects of PGI2 on regional blood flow distribution in anesthetized dogs, the tracer microsphere reference sample method was used. Intravenous PGI2 infusions (0.5 and 1.0 microgram/kg/min) increased renal, adrenal, splenic, small intestinal, brain and pituitary blood flow, whereas pancreatic, fundic and skeletal muscle perfusion were diminished by PGI2. Hepatic and myocardial blood flow remained unchanged. This study demonstrates striking differences in regional vascular sensitivity to PGI2, which should be kept in mind when evaluating the potential therapeutic usefulness of PGI2 in a variety of clinical situations.

Anesthesia↗
PubMed1982

Primary cultures of rat hepatocytes as a model system of canalicular development, biliary secretion, and intrahepatic cholestasis. I. Distribution of filipin-cholesterol complexes during de novo formation of bile canaliculi.

Hepatocytes in primary monolayer culture reconstitute structural intact bile canaliculi sealed by tight junctions. Using filipin as a cytochemical marker for cholesterol-like membrane components in conjunction with the techniques of freeze fracture and thin sectioning, we have studied the distribution of cholesterol during the development of the biliary pole of cultured hepatocytes. It was found that the development of bile canaliculi is characterized in its very early stage by huge accumulations of filipin-cholesterol complexes located at distinct domains of the contiguous membrane. They were surrounded by junction formation zones almost devoid of these complexes, in which the alignment of intramembranous particles takes place. Maturation of the bile canaliculi was accompanied by dispersion of cholesterol within the canalicular membrane and its removal by segregation of cholesterol-rich membrane whorls and vesicles into the lumen. Finally, the luminal membranes, and particularly the areas studied with microvilli, contained only very few filipin-cholesterol complexes. In some cases, these seemed to be still arranged in small clusters. These alterations suggest a crucial role of cholesterol-rich membrane domains during initiation of a biliary polarity. On the other hand, cholesterol-poor (thus probably more fluid) areas might be required for the assembly of tight junctions, and appear to constitute the secretory active apical membrane present in the mature bile canaliculus.

Animals↗
PubMed1982

Primary cultures of rat hepatocytes as a model system of canalicular development, biliary secretion, and intrahepatic cholestasis. II. Taurolithocholate-induced alterations of canalicular morphology and of the distribution of filipin-cholesterol complexes.

Hepatocytes in primary monolayer culture treated with taurolithocholate showed distinct ultrastructural changes localized primarily to the bile canalicular membrane. These alterations comprised disturbance and proliferation of tight junctions, dilatation of the canaliculi, loss of microvilli, thickening of the pericanalicular ectoplasm, and bizarre lamellar transformations of canaliculi. In freeze-fracture replicas the lamellae projecting into the canalicular lumen were found to be devoid of intramembranous particles. Localization by the use of filipin of cholesterol in plasma membranes of taurolithocholate affected hepatocytes revealed an extensive accumulation of cholesterol in membranes of dilated canaliculi, and also in outpouchings of the contiguous membrane in the ultimate vicinity. Furthermore, a pronounced segregation of cholesterol-rich membrane material into the lumen of dilated canaliculi and into enlargements of the intercellular space could be observed in thin sections. In contrast, a total absence of cholesterol was noted in the lamellar projections of the bizarre transformed canaliculi. The reliability of these findings and their consequences for the mechanism of taurolithocholate-induced cholestasis are discussed and it is suggested that the incorporation of cholesterol into the canalicular membrane reflects only one aspect of the cholestatic effect of taurolithocholate. An additional aspect seems to comprise the dislocation of membrane bound proteins and perhaps other membrane components. This is probably caused by independent mechanisms.

Animals↗
PubMed1981

Are aminosugars ototoxic?

The ototoxicity of the kanamycin fragment 3-amino-3- deoxy-D-glucose (3-aminoglucose, kanosamine), was investigated by perilymphatic perfusion in the guinea pig. Concentrations of 10 or 28 mM of this compound had no effect on cochlear microphonic potentials (CM), contrasting with previous observations (Owada 1962). Kanamycin at 1 mM decreased CM significantly under otherwise identical conditions. The action of kanamycin was at least partially reversible.

Animals↗
PubMed1981

[Vessel structure and blood supply of free skin transplants in animal experiments in relation to their vessel supply].

In the total abdominal island skin flap of the rat based on both epigastric vessels in the groin, postoperative development after arterial or venous or complete division of the neurovascular bundle was documented. Photographic documentation, planimetry of the surviving skin area were used as methods together with evaluation of the blood supply of the flaps by Xe-133 clearance. The resulting new architecture of vessels was shown photomacroscopically by Indian ink injection. The function of arterial inflow and venous outflow was shown by microangiographical fluorescent methods. Hence, it was possible to combine special operation methods with definite new vessel structures, typical necrotic areas and postoperative mean value clearance results. Due to the difference of the xenon clearance results in individual cases, this method proved incapable of giving a safe prognosis on the survival of the special flap. Fluorescent microangiography pointed to the type of surgery which had been selected, and allowed functional evaluation of the blood supply of the flap.

Angiography↗
PubMed1980

Brain angiotensin II stimulates release of pituitary hormones, plasma catecholamines and increases blood pressure in dogs.

1. The mechanisms of central angiotensin II blood pressure effects in conscious dogs on normal or sodium-deficient diets were examined. 2. The biosynthesis of brain angiotensin II in cerebrospinal fluid from its local precursor angiotensinogen was induced in vivo by injection of 0.5 unit of hog kidney renin through a chronically implanted cannula into the third brain ventricle in conscious dogs. 3. Intracerebroventricular administration of renin induced an increase of arterial blood pressure and a marked drinking response under both dietary regimens. Sodium restriction had no effect on the magnitude of the central angiotensin pressor response. 4. Plasma concentrations of renin and angiotensin II decreased, and plasma antidiuretic hormone, noradrenaline, adrenaline and corticosterone increased, in both groups of dogs. 5. Simultaneous intraventricular administrations of captopril with renin inhibited the central renin effects. Intracerebroventricular injections of [Sar1, Val5, Ala8] angiotensin II alone increased plasma renin and angiotensin II concentrations. 6. It is concluded that endogenous brain angiotensin II participates in central mechanisms of blood pressure regulation by the stimulation of the release of antidiuretic hormone, adrenocorticotrophic hormone, adrenaline and noradrenaline.

Angiotensin II↗
PubMed1980

[The interaction of methemoglobin and modified poly-(hydroxyethylmethacrylates) studied by spectroscopic methods].

The interaction between methemoglobin (MetHb) and macroporous matrices on the basis of polymethacrylates was investigated by means of optical and e.p.r. spectroscopy. The spectroscopic data show that the adsorption of MetHb to imidazole-containing matrices occurs by complex formation between matrix-bound imidazole and the iron of the prosthetic group, with all 4 polypeptide chains of the MetHb molecule being included in the interaction. The adsorption to hydrophobic side chains containing matrices leads, via the protein-matrix interaction, to considerable disturbances of iron protoporphyrin IX in equilibrium or formed from protein-contacts, which are of general importance with respect to the functional variablity and control, respectively, of iron porphyrins in hemoproteins. In case of matrix containing n-hexyl groups deoxyHb is oxidized by O2 to MetHb, instead of being oxygenated to HbO2. Not all prosthetic groups are able to bind N-3. With the increase in hydrophobicity of the matrix a conformational change is enforced leading in the beta-chains to the direct interaction between iron and sulfur of cysteine (beta-cys 92), as it is proved in all cytochrome P-450 and other model compounds.

Animals↗
PubMed1979

Effects of modern loop diuretics on the inner ear a quantitative evaluation using computer technics.

The effects of some modern high ceiling loop diuretics on the guinea-pig's inner ear are tested. Short-time experiments are run registrating the cochlear microphonic potentials (CMP) before and after i.v. bolus injections of a diuretic. A 100-point matrix program is performed by automatic sampling of the CMPs after stimulating by five frequencies at 20 sound pressure levels each. Data can be plotted in different scales within 10 min after the end of a whole-day experiment. The data are on-line processed by a IBM 1800 computer.

Animals↗
PubMed1976

Blood pressure response to central and peripheral injection of angiotensin II and 8-C-phenylglycine analogue of angiotensin II in rats with experimental hypertension.

1. We have compared the effect of central and peripheral administration of angiotensin II and (1-succinamoly-5-valine-8-phenylglycine)angiotensin II on blood pressure of male conscious unrestrained rats with normal blood pressure, and with spontaneous hypertension or chronic renal hypertension. 2. After central and peripheral injection of angiotensin II all rats exhibited a significant dose-related increase in blood pressure. 3. Administration of the analogue was without effect in normotensive rats. Ten-weeks-old rats with spontaneous hypertension showed a significant blood pressure decrease after central injection, but an increase after peripheral injection. This centrally induced decrease could not be observed in spontaneously hypertensive rats 14 weeks old. In these animals the analogue increased the blood pressure. In rats with chronic renal hypertension in contrast to peripheral injection, central administration decreased the pressure significantly. 4. Plasma renin activity was not changed after central injection of the analogue in normotensive rats. 5. These observations suggest the participation of the intrinsic brain isorenin-angiotensin system in central blood pressure regulation in these forms of experimental hypertension.

Angiotensin II↗
PubMed1975

[Clofibrate treatment of diabetics with hyperproteinemias (author's transl)].

The effect of a six weeks clofibrate treatment on lipid metabolism was investigated in a collective of 38 constantly maladjusted elderly diabetics with an average of 30% overweight and various forms of hyperlipoproteinemias. Clofibrate produced a significant lowering of the mean triglyceride and cholesterol levels, whereas no such effect was observed in an untreated control group. Related to the various types of hyperlipoproteinemia (IIa, IIb and IV), the group treated with clofibrate showed a rate of normalization of nearly 50%, while the rate of improvement in the untreated control group was 10%.

Adult↗
PubMed1975

[The radiofibrinogen test in differential diagnosis of fresh deep venous thrombosis].

The radio-fibrinogen test is a simple and sensitive method for diagnosing deep vein thrombosis. Intravenously administered radioactive labelled fibrinogen is incorporated as radioactive fibrin in freshly developing thrombi, and such labelled thrombi may be detected on the body surface with nuclear medical equipment. Homologous iodine 125 labelled fibrinogen is chiefly used since it is known not to transmit viral hepatitis. The weak gamma emittor 125-I allows the use of a portable scintillation detector rate meter with an easily moved measuring device. This bedside method does not involve discomfort for the patient. The correlation between ascending phlebography and the radioactive fibrinogen test is more than 90 percent. The radiofibrinogen test may be used to study thromboembolic diseases, to evaluate drugs for prevention of thromboembolic complications and to confirm clinically suspected fresh deep vein thrombi. Details of the method as used in several thousand measurements are given.

Diagnosis, Differential↗
PubMed1975

[Evoked response audiometry of the guinea pig before and after drop in hearing induced by furosemid (author's transl)].

Using particular surface electrodes evoked response audiometry (ERA) can be applied to small laboratory animals without any sedation or anaesthesia. In addition to other methods we have studied in this way the influence of extreme doses of Furosemid on the guinea pig inner ear. 6-20 mg Furosemid per 100 g of bodyweight (about 100 times the human therapy dose) were applicated i.v. within 5 min resulting in a drop of hearing immediately. For the anaesthesized animal the cochlear microphonic potentials (CM) decrease simultaneously, indicating Furosemid to act at the inner ear itself. By both methods recovery of inner ear function is seen to start about 10 min later according to the little biological half life of Furosemid. As being restricted in respect of time for the CM-measurements we are sure about reversibility only by the ERA-method.

Animals↗