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Biomedical subjects

H Bader

Publications and source records attributed to H Bader.

At least 73 records · Page 4Linked to original sources
PubMed1983

Importance of the gerontology of elastic arteries in the development of essential hypertension.

After discussing the changes of elastic type vessels with age, several possibilities for the resetting of baroreceptors in elastic type vessels are proposed: (1) Short-term resetting. On the basis of the architecture of the wall of elastic type vessels and the physical behavior of tubes, a pressure control organ within the vessel wall is proposed, by which, due to change in contraction of the vascular smooth muscles, the stress of the baroreceptors is changed and with it their set point relative to the blood pressure. This change can occur within seconds. (2) Mid-term resetting. The wall of elastic type vessels thickens, after a prolonged forced increase of blood pressure, decreasing the ratio of radius to wall thickness. Since the wall stress is proportional to the ratio of radius to wall thickness and the baroreceptors depend on the wall stress, they will now regulate the blood pressure on an elevated level. This change will be accomplished within days or weeks. (3) Long-term resetting. With age the wall of elastic type vessels becomes stiffer. Due to the peculiar physical behavior of tubes, this means that the wall stress decreases at a given blood pressure. Therefore, to maintain the same mean blood pressure throughout life, the baroreceptors have to adjust to the continuously decreasing wall stress. If this does not occur, the blood pressure will rise. Actually, the calculated increase of proposed blood pressure due to the decreasing wall stress parallels the recorded increase in blood pressure with age of the general population.

Adolescent↗
PubMed1983

[Liposarcoma of the gallbladder and the peritoneum. A case report].

We report a case of a male patient who was cholecystectomized at the age of 79. We diagnosed an intramural myxoid liposarcoma of the gall bladder without signs of metastasis. Two years later at autopsy we found a diffuse spread of the same type of tumour on mesentery, omentum maius, parietal and visceral peritoneum. The unusual primary site of the tumour is pointed out referring to literature, the question of primary multicentric liposarcoma resp. diffuse peritoneal metastases is discussed.

Aged↗
PubMed1982

A model for the regulation of the calmodulin-dependent enzymes erythrocyte Ca2+-transport ATPase and brain phosphodiesterase by activators and inhibitors.

Acidic phospholipids, unsaturated fatty acids and limited proteolysis mimic the activating effect of calmodulin on erythrocyte Ca2+-transport ATPase and on brain cyclic nucleotide phosphodiesterase, as has been reported previously in several studies. Three different antagonists of calmodulin-induced activation of these enzymes were tested for their inhibitory potency on the stimulation produced by the other activators. Trifluoperazine and penfluridol were found to antagonize all the above mentioned types of activation of Ca2+-transport ATPase in the same concentration range. Both inhibitors also can reverse the activation of phosphodiesterase by oleic acid, phosphatidylserine and calmodulin at similar concentrations. However, in contrast with erythrocyte Ca2+-transport ATPase, activation of phosphodiesterase by limited tryptic digestion cannot be antagonized by penfluridol and trifluoperazine. Calmidazolium, formerly referred to as compound R 24571, was found to be a relatively specific inhibitor of calmodulin-induced activation of phosphodiesterase and Ca2+-transport ATPase, since antagonism of the other activators required much higher concentrations of the drug. The results suggest that the investigated drugs exert their inhibitory effect on calmodulin-regulated enzymes not solely via their binding to calmodulin but may also interfere directly with the calmodulin effector enzyme. In addition, a general mechanism of activation and inhibition of calmodulin-dependent enzymes is derived from our results.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1982

Multimers of anionic amphiphiles mimic calmodulin stimulation of cyclic nucleotide phosphodiesterase.

Oleic acid, phosphatidylserine and pyrenedecanoic acid were found to activate calmodulin-deficient cyclic nucleotide phosphodiesterase at concentrations above their critical micellar concentration. In contrast with calmodulin these activators do not require the presence of Ca2+ for their action. It is shown that the size of phosphatidylserine vesicles is of crucial importance with respect to the activating potency of phosphatidylserine. Fluorescence measurements with the probe pyrenedecanoic acid revealed that micelles rather than monomers are the active species for stimulation of phosphodiesterase. There are indications that this result also may be applied to the other activators.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1982

Contrasting renal effects of different antihypertensive agents in hypertensive rats with bilaterally constricted renal arteries.

Systemic and renal effects of the vasodilators dihydralazine and minoxidil were compared with those of the converting-enzyme inhibitor captopril (SQ 14225) and the AII antagonist sarisoleucin (Sar1Ile8-AII) in chronically sodium-depleted, two-kidney, two-clip hypertensive rats. Arterial blood pressure normalized in all experimental groups within 24 hours and remained normal until the end of the experiment. By day 4, plasma concentrations of creatinine and urea in animals treated by captopril or sarisoleucin were significantly higher than those measured after the administration of dihydralazine or minoxidil. Renal tubular lesions were also more frequently observed after the renin-angiotensin system (RAS) was blocked than they were after vasodilatation was induced by direct smooth muscle relaxation. Captopril and sarisoleucin stimulated the RAS more extensively than dihydralazine and minoxidil did. The results indicate that, in the presence of bilateral renal artery stenosis and sodium deprivation, systemic blood pressure normalization after the blockade of the RAS may be accompanied by acute renal failure. This may be explained partially by poststenotic renal hypotension, but it may also reflect a reduction of the GFR because of the blockade of intrarenal actions of AII.

Animals↗
PubMed1982

An investigation of sperm migration into the oviducts of the mare.

A total of 23 mares were inseminated once within 0-6 h after clinical detection of ovulation, 14 with fresh and 9 with deep-frozen semen containing 0.1 x 10(9) to 4.7 x 10(9) motile spermatozoa. Within these two groups, the mares were slaughtered 2, 4 or 6 h after insemination and their genital tracts removed. The utero-tubal junction, isthmus and ampulla ipsilateral to the ovary in which ovulation occurred were flushed separately for sperm recovery. In 1 or 2 mares of each group, the uterine horn and corpus uteri, the cervix and vagina were also flushed. Tissue samples were collected from the contralateral oviduct and the other genital regions and prepared for scanning electron microscopy to show spermatozoa distribution in situ. Flushings were also prepared for scanning electron microscopy. There were no significant differences in the extent of sperm migration and in the number of spermatozoa in the different regions of the oviduct 2, 4 or 6 h after insemination of fresh or frozen semen. There was, however, a striking difference in sperm number within the time intervals examined; the numbers were greatest at 4 h after insemination. SEM of spermatozoa in the various regions of the oviducts failed to indicate any alterations to the sperm-head membranes that could be associated with sperm capacitation. The majority of spermatozoa found in the uterotubal junction, isthmus and ampulla showed morphological integrity.

Acrosome↗
PubMed1981

[Malignant fibrous histiocytoma after supracondylar femoral fracture (author's transl)].

Supracondylar slanting fracture of the femur was treated by osteosynthesis in a 14-year-old girl. Two months after removal of the plate and screws, 10 months after the initial trauma, a malignant bone tumour in the form of malignant fibrous histiocytoma was diagnosed at the same location after a renewed fracture. The preceding trauma may be assumed to be one of the reasons for occurrence of this rare tumour.

Adolescent↗
PubMed1981

[Mechanism of action of AR-L 115 BS compared to caffeine].

The influence of 2-[(2-methoxy-4-methylsulfinyl)phenyl]-1H-imidazo[4,5-b]pyridine (AR-L 115 BS) and caffeine on Ca++-ATPase activity, Ca++-uptake and Ca++-release (efflux greater than influx:release) of the vesicles of sarcoplasmic reticulum of pig heart was investigated. In contrast to caffeine, 1 mmol/l AR-L 115 BS produced partial inhibition of Ca++-uptake of the vesicle while Ca++-release was only slightly affected. It was not possible to determine the effect of high concentrations of AR-L 115 BS and caffeine on the Ca++-ATPase activity because these substances showed a marked interference with the reagents of the reaction mixture.

Animals↗
PubMed1980

Influence of monovalent ions on the activity of the (Ca2+ + Mg2+)-ATPase and Ca2+ -transport of human red blood cells.

In reconstituted human red blood cells a difference was found in (Ca2+ + Mg2+)-ATPase activity and in Ca2+ efflux at 37 degrees C, depending on the side of the membrane at which the monovalent cations K+ and Na+ were placed. Under the conditions used, (Ca2+ + Mg2+)-ATPase activity and Ca2+ efflux was highest when K+ (35 +/- 0.5 mM (+/- S.E.), mean of four experiments) was at the inside and Na+ (130 mM) at the outside of the ghost membrane.

Biological Transport, Active↗
PubMed1980

Structure and function of the kidney in diabetic glomerulosclerosis. Correlations between morphological and functional parameters.

Histological and clinical findings in 103 middle-aged patients suffering from diabetic glomerulosclerosis (gs) (biopsy material) are reported. In diabetic gs (as in other inflammatory and non-inflammatory glomerular disease) a statistically highly significant positive correlation exists between the grade of fibrosis of the renal cortical interstitium and the serum creatinine concentration at the time of biopsy. Rank correlations exist between vessel index and relative cortical interstitial volume on the one hand as well as serum creatinine concentration on the other. Significant differences are also shown to exist between the mean values of the cortical interstitium as well as the serum creatinine concentration and the vessel index in the four grades of diabetic gs. Severe glomerular lesions may be accompanied by a normal serum creatinine concentration, only if the interstitium shows no fibrotic changes. Mild glomerular lesions, when accompanied by an interstitial fibrosis, always have elevated serum creatinine concentrations. The incidence of hypertension, proteinuria, the nephrotic syndrome and hematuria in diabetic gs appears to vary greatly. From the highly significant correlation between the cortical interstitium and the serum creatinine concentration we presume the following: Alterations of the postglomerular vessels by interstitial fibrotic changes result in an increased resistance to renal cortical blood flow with a subsequent reduction of glomerular perfusion. This reduction of the glomerular perfusion may result in a rise of the serum creatinine concentration, independently of the severity of the glomerulosclerosis. It is also conceivable that glomerular function is affected by the malfunctioning atrophic tubules in areas of interstitial fibrosis.

Biopsy↗
PubMed1979

The effect of vesiculectomy on seminal characteristics in the stallion.

Successful unilateral extirpation of an inflamed seminal vesicle in a stallion led to systematic trials of the influence of a reduction and absence of the secretion of this gland upon semen characteristics. Operations were performed by the method described for the bull. The volume of ejaculates dropped and sperm concentration per ml increased in each of 2 stallions from which the seminal vesicles had been uni- or bi-laterally removed. Total sperm number and motility remained uninfluenced, but the percentage of eosin-stained spermatozoa increased in the unilaterally operated stallion and the percentage of abnormal spermatozoa increased significantly in both. Concentration of citric acid per ml and per ejaculate was significantly reduced after bilateral vesiculectomy. Ergothioneine concentration per ml increased in the unilaterally and in the bilaterally operated stallion.

Animals↗