Search PubMed⌕ Search

Biomedical subjects

P Weber

Publications and source records attributed to P Weber.

At least 343 records · Page 19Linked to original sources
PubMed1976

[Microspectrometric quantification of 4-hydroxypentenal binding to protein thiols in Ehrlich ascites tumor cells].

After 30 minutes in 5.10(-3) M hydroxypentenal (HPE) the microscopically determinable proteinthiols (PSH) stained with DDD-Fastblue B decrease from 1,07 . 10(-14) to 0,61 . 10(-14) moles/cell. The loss of PSH of 0,46 . 10(-14) moles has a confidential range (99%) of +/- 0,12. As HPE reacts with thiols by an addition to the C3 = C2-group, the aldehydic group remains reactive and can be recognized intracellulary and quantitatively determined with 2,4-dinitrophenylhydrazine, whereby an uptake of 0,63 . 10(-14) moles of HPE per single cell is observed (confidential range +/- 0,11). The broad overlapping of the confidential ranges indicates clearly that the loss of PSH corresponds to the uptake of HPE. From the statistical distribution diagrams it can be seen that the PSH of practically all cells take part in the reaction, if however, to very different extent; the cells with high PSH concentrations being the most reactive ones.

Aldehydes↗
PubMed1975

The histochemical application of dansylhydrazine as a fluorescent labeling reagent for sialic acid in cellular glycoconjugates.

A new method for the fluorescent staining of stalic acid-containing glycoconjugates in fixed tissues is described. The procedure uses mild periodate oxidation, followed by condensation with dansylhydrazine and reduction of the hydrazones to hydrazines. The specificity of the reaction for sialic acid is tested on model glycoconjugates. The procedure gives superior resolution in comparison to the standard periodate Schiff procedure for cellular carbohydrates.

Animals↗
PubMed1975

Angiotensin stimulated AVP-release in humans.

Release of arginine vasopressin (AVP) from rat neurohypophysis in in vitro studies is significantly augmented by the addition of angiotensin (A-II), and in in vivo studies in dogs renin and A-II were found to stimulate secretion of AVP. Both these results suggest the existence of a direct relationship between the salt regulating renin-angiotensin-aldosterone system and the water controlling AVP system. To evaluate whether such observations apply also in man a sensitive double antibody radioimmunoassay for AVP was developed [17, 18]. Basal plasma levels of AVP in recumbent humans without salt and fluid restriction at room temperature were 3.4 plus or minus 2.2 pg/ml, and 30 min after the onset of an A-II infusion at a concentration of 3-30 ng/min-kg, a significant increase of AVP was found. Maximum measurements were 2-5 times basal levels which returned to normal within 90 min. During the A-II infusion one also noted a 20 mm Hg rise in blood pressure, accompanied by a significant decrease in plasma renin activity. During the same period serum osmolality and serum sodium concentration did not change. Elevation of blood pressure by norepinephrine was not followed by any detectable change of plasma AVP levels, thus excluding a nonspecific blood pressure effect.

Angiotensin II↗
PubMed1975

Experimental oliguric acute renal failure: protective effects of renomedullary autotransplants.

An acute circulatory renal failure (ARF) was induced in 18 rabbits by temporary ischemia of the remaining kidney 8 days after unilateral nephrectomy and subcuteaneous autotransplantation of renomedullary tissue.--Mortality in the postischemic course was 50% in treated animals but 100% in the control group (n = 18) without autotransplantation. In the postischemic period plasma urea concentration was significantly lower (p smaller than 0.005) in the surviving transplanted animals and excretion of sodium and water significantly higher (p smaller than 0.005) as compared with the control group. Plasma renin values which were significantly lower than thos of the control(p smaller than 0.005) had decreased significantly even as compared with the initial values. These results indicate that hormonal substances are produced in interstitial cells of renomedullary autotransplants exerting a distinct protective effect against experimental acute renal failure. Decreased plasma renin activity may point to an inhibition of circulating and/or intrarenal renin by lipids originating from the transplants. Changes in sodium and water excretion indicate effects of circulating prostaglandins

Acute Kidney Injury↗
PubMed1975

Plasma renin activity and renal sodium and water excretion following infusion of arachidonic acid in rats.

Plasma renin activity (PRA) and urinary sodium and water excretion were measured following infusion of the prostaglandin (PG) precursor arachidonic acid (C20:4) in normal hydrated rats (saline i.v.:0.5 ml/hr/100 g body weight) and in rats with moderate volume expansion (saline i.v.:1.5 ml/hr/100 g body weight). Nonhypotensive doses of C20:4(40-70 mu/min/100 g b.w.) increased PRA in both normal and volume-expanded rats (p less than 0.05, and p less than 0.025, respectively). In volume-expanded rats, C20:4 was followed by reduced lrine volume (p less than 0.01) and sodium excretion (p less than 0.001) in comparison to volume-expanded control rats, whereas in normal hydrated rats these parameters remained unchanged after C20:4. The present results indicate that the C20:4-stimulated PG-synthetase system can increase PRA independently of the extracellular fluid volume. Furthermore, these results suggest a complex interrelationship between PG-synthetase action, activation of the renal renin-angiotensin system and urinary water and sodium excretion.

Animals↗
PubMed1975

Reaction constants of renin in juxtaglomerular apparatus and plasma renin activity after renal ischemia and hemorrhage.

Reaction constants of renin in juxtaglomerular apparatus and plasma renin activity after renal ischemia and hemorrhage. During and after total renal ischemia and acute hemorrhage, renin activity in plasma (PRA) and microdissected juxtaglomerular apparatus (JGA) of rabbits were investigated. In controls, the apparent Michaelis-Mentoen constant (MMC) of semipurified standard renin of rabbits was 1025 plus or minus 223 SD ng/ml. Plasma renin of normal rabbits showed similar values: 1062 plus or minus 138 SD ng/ml. Intrarenal JGA renin, however, showed a great scatter of MMC (920 to 4760 ng/ml) and a significantly higher mean value of 2572 plus or minus 1156 SD ng/ml (pis less than 0.001). After complete renal ischemia by clamping both renal arteries for a 90-min period, the following results wereobtained: 1) Sixty min after the beginning of ischemia, PRA decreased from 20.9 plus or minus 9.8 SD to 7.6 plus or minus 5.2 SD ng/ml-hr (P is less than 0.05) and increased to 103, 68 and 42 ng/ml-hr 10, 30 and 90 min after removal of the clamps, respectively (P is less than 0.05).

Animals↗
PubMed1975

Radioimmunoassay of arginine vasopressin in human plasma.

Antibodies for the radioimmunoassay of arginine vasopressin (AVP) described here were produced in rabbits using synthetic AVP coupled to rabbit gamma-globulin with carbodiimide. In three out of six rabbits, significant antibody titres were obtained. Using the best antisera produced, 40% of labeled AVP was bound at a final dilution of 1:50.000. After iodination of synthetic AVP with 125I using the chloramin-T method, a gel filtration on Sephadex G-25 was performed to purify the iodinated AVP. For separation of antibody bound and free hormone, a second antibody precipitation was used. There was no crossreactivity with oxytocin. AVP was extracted from plasma after ammoniumsulfate precipitation of the proteins by adsorption to Florisil. The recovery of AVP added to plasma in amounts between 5-25 pg/ml was 60 +/- 15% (n equals 6). The minimum amount of AVP detectable was 1 pg per ml plasma. The plasma level in normal adults under standard conditions was 3.4 +/- 2.2 pg/ml. This is in agreement with data recently published by other researchers. The applicability and reproducibility was further tested in measurements of samples taken hourly during the entire day under water diuresis and after hormonal stimulation of AVP.

Animals↗
PubMed1975

[Preoperative radiotherapy of bladder cancer].

Based on the observation of 58 patients with carcinoma of the bladder the effect of preoperative irradiation is reported. After application of 3500 Rad in about four weeks the examination of the surgery preparations revealed histological absence of tumor cells in one third of the cases approximately. The irradiation technique used is described and also the effects and side-effects of synchronization induced by 5-fluorouracil in a part of the group. Consequences for the therapeutic proceeding with regard to the carcinoma of the bladder are discussed.

Bone Marrow Diseases↗