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Biomedical subjects

J Bachmann

Publications and source records attributed to J Bachmann.

At least 37 records · Page 2Linked to original sources
PubMed1993

[Left ventricular dilatation after myocardial infarct].

The aim of this prospective study was to investigate if left ventricular dilatation is confined to the early months following myocardial infarction, or if it is a progressive process over several years. One hundred patients (pts) who suffered from stable angina or had undergone myocardial infarction, could be examined twice by coronary arteriography including ventriculography in an interval of 52 +/- 14 months. The patients were retrospectively divided into three groups: 41 pts (group A) had coronary heart disease without prior myocardial infarction, in 29 pts (group B) the first examination was performed within (mean 2 +/- 1 mo.) and in 30 pts (group C) beyond 6 months after myocardial infarction (mean 32 +/- 24 mo). The three groups were comparable concerning clinical data, but more pts with former myocardial infarction had multi-vessel disease (34 of 59 vs 16 of 41 pts) and depressed left ventricular function. Left ventricular angiography was performed in RAO view 30 degrees after enddiastolic pressure (LVEDP) was registered. Left ventricular enddiastolic and endsystolic volumes (EDVI and ESVI) were calculated by use of a modified Simpson's rule equation. In group A, EDVI and LVEDP remained constant, whereas ESVI increased slightly but significantly. Pts of group B and C had significantly higher volumes, which increased significantly in both groups over a mean of 52 months. About half the pts suffered from ventricular dilatation independent of progression of underlying coronary sclerosis. Consecutively, left ventricular ejection fraction decreased and LVEDP rose significantly in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Role of tissue renin in the pathophysiology of hypertension in TGR(mREN2)27 rats.

A transgenic rat line, TGR(mREN2)27, was established by introducing the murine Ren-2 gene into the genome of rats by microinjection techniques. These rats exhibit severe hypertension, making them an interesting model in which to study the role of renin in the pathophysiology of hypertension. However, although the additional renin gene is the only genetic difference compared with control rats, the exact mechanism of hypertension in TGR(mREN2)27 rats is still unclear. It cannot be attributed to a stimulation of the endocrine renin-angiotensin system or to an overexpression of renin in the kidney, since plasma and kidney renin and renin gene expression in the kidney are low in these animals. Here we describe recent progress made toward elucidating mechanisms of hypertension in TGR(mREN2)27 rats. 1) TGR(mREN2)27 rats were bred to homozygosity. The development of high blood pressure in homozygous rats is accelerated compared with that of heterozygous rats. This is paralleled by a higher mortality rate in homozygous TGR(mREN2)27 rats. Blood pressure and mortality rate of homozygous transgenic rats were effectively reduced by 10 mg captopril per kilogram body weight. 2) Treatment of 8-week-old heterozygous TGR(mREN2)27 rats with 10 mg/kg body wt per day of the angiotensin II receptor antagonist DuP 753 for 4.5 weeks normalized blood pressure. After withdrawal of the drug, blood pressure increased rapidly, reaching control levels after 3 weeks. In another group of TGR(mREN2)27 rats treated with 0.5 mg/kg per day, there was no change in blood pressure. Plasma renin and plasma angiotensin II were significantly higher in the high-dose group compared with the low-dose group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Cortex Hormones↗
PubMed1991

Sexual dimorphism of blood pressure: possible role of the renin-angiotensin system.

The prevalence of hypertension in men is higher than in women and the onset of this disease is earlier in male than in female subjects. In spontaneously hypertensive rats, males also have higher blood pressures than females. Evidence from epidemiological, physiological, molecular biological and morphological studies concerning this sexual dimorphism is reviewed. We demonstrate that the gonadal steroids testosterone and estrogen have important effects on the gene regulation of the renin-angiotensin system. This may in part contribute to the sexual dimorphism in blood pressure control. The direct effect of steroid hormones on genes related to hypertension provides a suitable paradigm to improve our understanding of molecular and cellular mechanisms of cardiovascular control.

Angiotensin II↗
PubMed1991

Effect of plasma from patients with essential hypertension on vascular resistance in the isolated perfused rat kidney.

1. Isolated perfused rat kidneys were used to study the effects of plasma fractions obtained by gel filtration from essential hypertensive patients (n = 40) and from normotensive subjects (n = 36) on resistance vessels. Perfusion pressure was recorded at a constant flow. 2. Plasma fractions were obtained by gel filtration and contained substances with a molecular mass in the range 1000-1500 Da. The plasma fractions from hypertensive patients used in this study had been shown to increase blood pressure after intravenous injection in rats. 3. In the isolated rat kidneys, the hypertensive fractions increased perfusion pressure by 20 +/- 17 mmHg (mean +/- SD, range 5-58 mmHg, n = 40). The analogous fractions from normotensive subjects did not change perfusion pressure significantly. 4. In Ca2(+)-free medium containing 2 mmol/l ethyleneglycol bis-(aminoethyl ether)tetra-acetate, the change in perfusion pressure induced by active plasma fractions was reduced by 95.2 +/- 6.3%. Addition of nifedipine to the perfusion medium reduced, but did not abolish, the pressure response of the kidneys. 5. In solutions containing phentolamine or saralasin, vasoconstriction was not reduced. 6. Thus in the active fractions from hypertensive plasma, a vasopressor agent with direct action on resistance vessels can be demonstrated. This substance probably acts by increasing Ca2+ influx in vascular smooth muscle cells.

Adult↗
PubMed1990

Effect of plasma from essential hypertensives on vascular tone of aortic strips, isolated perfused mesentery and isolated perfused kidney.

Different vascular models of normotensive Wistar rats, including aortic strips, isolated perfused mesentery and isolated perfused kidney, were used to study hemodynamic effects of plasma fractions obtained by gel filtration from the blood of essential hypertensive and normotensive subjects. Plasma fractions from essential hypertensives studied had been shown to increase blood pressure after intravenous injection in rats. In the aortic strips, 50 microliters of a hypertensive fraction (HF) elicited a calcium-dependent contraction of 0.14 +/- 0.035 mN (n = 20, p less than 0.05), which was inhibited by nifedipine, whereas tension of the strips was not significantly changed by normotensive fractions (NF) (n = 17). In the isolated perfused mesentery preparation, no significant change of perfusion pressure by HF or NF could be demonstrated (n = 10). In the isolated perfused kidney, a transient increase of perfusion pressure was induced by HF (19.5 +/- 16.6 mm Hg, n = 40, P less than 0.001) but not by NF. This increase was abolished in calcium-free, 2 mmol/l EGTA containing perfusion medium. The response was diminished, but not abolished by nifedipine. These data demonstrate vasopressor properties of plasma from essential hypertensives, which might be the consequence of a circulating vasoconstrictor substance in the blood of essential hypertensives.

Adult↗
PubMed1990

Effect of plasma from essential hypertensives on tension of aortic strips.

The effect of fractions of plasma from essential hypertensive (n = 27) and normotensive subjects (n = 26) on the tension of aortic strips (n = 27) from normotensive rats was examined. The fractions obtained from hypertensive patients had been shown to increase blood pressure, when injected intravenously in a normotensive rat. In aortic strips the hypertensive fractions elicited a transient relaxation of variable amplitude and subsequently a sustained contraction. The normotensive fractions did not alter tension of the strips significantly. In Ca2+ free medium and after addition of nifedipine hypertensive plasma fractions did not induce a contraction, whereas in Na+ free medium the contraction was not abolished. It is concluded that in the fraction of hypertensive plasma containing substances with a molecular weight in the range of 1000-1500 Da a vasopressor agent with direct actions on arterial smooth muscle is present. The substance probably acts by increasing Ca2+ influx in vascular smooth muscle.

Adult↗
PubMed1985

Potential human health effects of acid rain: report of a workshop.

This report summarizes the potential impact of the acid precipitation phenomenon on human health. There are two major components to this phenomenon: the predepositional phase, during which there is direct human exposure to acidic substances from ambient air, and the post-depositional phase, in which the deposition of acid materials on water and soil results in the mobilization, transport, and even chemical transformation of toxic metals. Acidification increases bioconversion of mercury to methylmercury, which accumulates in fish, increasing the risk to toxicity in people who eat fish. Increase in water and soil content of lead and cadmium increases human exposure to these metals which become additive to other sources presently under regulatory control. The potential adverse health effects of increased human exposure to aluminum is not known at the present time.

Acids↗
PubMed1984

[Syndrome of supravalvular aortic stenosis (Williams-Beuren syndrome) in association with changes in the kidney and efferent urinary tract].

We investigated the urinary tract in 19 out of 30 children having the Williams-Beuren-Syndrome. 14 of these children showed all signs of the syndrome, whereas 8 children had only the typical cardiological findings without the pathognomonic facies and without major mental retardation. These two different types will be designed as type I and type II respectively. In 12 of the children belonging to type I there were anomalies of the kidneys and the lower urinary tract including 1 child having nephrocalcinosis. The various anomalies were found as single or combined lesions. As for type II there was only 1 child (out of 5) that showed a stenosis of the urethra and at the origin of the ureter in combination with a hydronephrosis. The frequency of anomalies of the urinary tract appears to be very high in type I. However, because of the small number of patients it is impossible to reach statistical significance in comparing the different frequencies within type I and type II. Further investigations are necessary to clarify the problem.

Aortic Valve Stenosis↗
PubMed1983

Comparison of two methods of profile prediction in surgical treatment of mandibular prognathism.

Two methods for prediction of the soft tissue profile subsequent to oblique subcondylar osteotomy for correction of mandibular protrusion were evaluated. The first one included distalization of the mandible into an Angle Class I relationship. The amount of distalization and any vertical changes were transferred to the tracing, and the anticipated new profile was drawn. The second method was based on the profile means of a group of "normal" persons and was aimed at correction of both sagittal and vertical discrepancies. Fifty patients were studied. A double set of prediction tracings was made according to both methods; and the results were compared with the actual postoperative results and with a "normal" control group. Both methods were usable, as the predictions were considered satisfactory if they were within one standard deviation from the mean of the control group. The sagittal changes were somewhat exaggerated by both analyses. The vertical changes were much better expressed by the profile prediction. Such changes are difficult to create by the vertical subcondylar osteotomy. Consequently, the model prediction seems most suitable for planning profile changes in surgical techniques that include mobilization of one main mandibular fragment.

Adult↗