Search PubMed⌕ Search

Biomedical subjects

C Spieker

Publications and source records attributed to C Spieker.

85 records · Page 5Linked to original sources
PubMed1986

Elemental and trace element distribution in medical samples: analysis by proton-induced X-ray emission.

The analysis of trace elements is performed by proton-induced X-ray emission. The process is most effective if the velocity of the exciting particles--protons--is similar to the velocity of the electron on its orbit in the simple atomic model of Bohr. For K-shell electrons of the elements with 15 less than or equal to z less than or equal to 40 this requires proton energies of a few MeV, available from electrostatic van de Graaf accelerator machines. After knocking out the K-shell electron, the empty place is filled up by electrons jumping from higher orbits with simultaneous emission of characteristic X-rays, which are registered with a cooled Si (Li) detector. By a set of electrodes the beam can be swept across the specimen surface. Therefore this method yields an excellent correlation of trace element distribution within the morphological structure of organic tissue. In the present study the sweep went along a line perpendicular to the arterial wall layers (aortic, renal artery and heart muscle) of normotensive and spontaneously hypertensive rats. Along this line all elements and trace elements are recorded simultaneously. These are P, S, Cl, K, Ca, Fe, Cu, Zn, Br and Sr. The trace element content of the aortic wall and the renal artery, of 22 spontaneously hypertensive and 11 normotensive rats and of human heart muscle was investigated. The results demonstrate that Zn was only detected in the muscle-containing layers of the arteries. There was no different distribution between hypertensive and normotensive rats. However, Ca2+ was mainly detected in the smooth muscle-containing tunica media of hypertensive rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Ca2+ metabolism in arteries of spontaneously hypertensive rats: assessment by proton-induced X-ray emission.

Changes of intracellular Ca2+-metabolism have been considered to be of importance for the pathogenesis of essential hypertension. In the present study particle-induced X-ray emission (PIXE) was used to get information on the spatial distribution of Ca2+ in aortas and renal arteries of spontaneously hypertensive (SHR) and normotensive rats. Our findings demonstrate a significant Ca2+ elevation in the aorta and renal artery of SHR versus normotensive Wistar-Kyoto (WKY) rats (3317 +/- 734 micrograms Ca2+/g tissue versus 1623 +/- 569 micrograms Ca2+/g tissue and 3432 +/- 1867 micrograms Ca2+/g tissue versus 1050 +/- 554 micrograms Ca2+/g tissue).

Animals↗
PubMed1985

Ca2+ analysis in arteries of spontaneously hypertensive rats by proton-induced X-ray emission.

Numerous investigations have shown that Ca2+ plays an important role in the pathogenesis of hypertension. Intracellular Ca2+ measurements have been carried out with Ca(2+)-selective electrodes and the Quin 2 method. The present study used particle induced X-ray emission to investigate the Ca2+ distribution in arterial smooth muscle. This method correlates Ca2+ distribution with the morphological structure of the tissue. The Ca2+ content of the aortas and renal arteries was measured in 22 spontaneously hypertensive and 11 normotensive rats. The findings demonstrate significant Ca(2+)-elevation in the aortas of spontaneously hypertensive rats compared with the aortas of normotensive rats (3124.9 +/- 790.0 versus 2031 +/- 478 micrograms Ca2+/g; P < 0.05), whereas there was only a tendency to Ca2+ elevation in the renal arteries of spontaneously hypertensive rats compared with normotensive rats (3336.0 +/- 1798.0 versus 1533.2 +/- 1082.0 micrograms Ca2+/g; NS). The Ca2+ was mainly detected in the muscle containing tunica media.

Animals↗
PubMed1985

Essential hypertension versus secondary hypertension: discrimination by intracellular electrolytes.

Intracellular activities of sodium and calcium were determined in red blood cells in a group of 106 patients, consisting of essential and renal hypertensives and of normotensives with and without renal insufficiency. Calcium and sodium activities were elevated in essential hypertensives as compared to hypertensives suffering from renal insufficiency. Compared to normotensives without renal insufficiency higher sodium and calcium activities were measured in normotensives without renal impairment. Thus the results suggest that the determination of intracellular electrolytes might be a useful tool for the distinction of secondary hypertension. Furthermore, as yet unidentified humoral factors produced in the kidney might be involved in the regulation of the blood pressure, as a decrease in production of these hypothetic humoral factors (following the destruction of renal tissue) could be the cause for the changes in electrolyte composition.

Adult↗
PubMed1985

Influence of low and high cadmium diet in normotensive and hypertensive SH-rats.

Normotensive and SH-rats (Münster strain) were fed a cadmium-rich, normal or cadmium-poor diet. The blood pressure was slightly increased in normotensive rats after feeding a cadmium-rich diet and decreased after a cadmium-poor diet. In contrast, in SH-rats blood pressure was decreased after a cadmium-rich and increased after a cadmium-poor diet. This behavior of the blood pressure corresponded with the intra-erythrocytic Ca2+ activities. Whereas the calcium activities increased in the normotensive group after a cadmium-rich diet, the calcium activities decreased in the SH-group after cadmium feeding. It should be pointed out that normally the calcium activities were found to be elevated in SH-rats. Thus, cadmium feeding here had the same effect as a calcium antagonist.

Animals↗
PubMed1985

The evaluation of tissue Ca2+ by proton-induced x-ray emission in the arteries of spontaneously hypertensive and normotensive rats.

Numerous investigations have shown that Ca2+ plays a critical role in the pathogenesis of hypertension. The intracellular Ca2+ measurements were mainly carried out with Ca2+ selective electrodes. In the present study the particle-induced x-ray emission (PIXE) was used for investigating the Ca2+ distribution of arterial smooth muscle of spontaneously hypertensive and normotensive rats. PIXE yields a correlation of the Ca2+ distribution with the morphological structure of the arterial muscle. The Ca2+ content of the aortic wall of six spontaneously hypertensive and four normotensive rats was investigated. The results demonstrate that the tissue Ca2+ measurements found mainly in the smooth muscle containing tunica media of hypertensive rats are much higher (3105 micrograms Ca2+/g tissue +/- 569 micrograms Ca2+/g tissue) than of normotensive rats (2031 micrograms Ca2+/g tissue +/- 478 micrograms Ca2+/g tissue).

Animals↗
PubMedDate not supplied

Ambulatory 24-h blood pressure monitoring in essential hypertensives treated with the angiotensin-converting enzyme inhibitor ramipril.

A double-blind, crossover study was carried out on the antihypertensive effect of 5 mg ramipril. Continuous 24-h blood pressure monitoring was performed on 15 essential hypertensives [mean (+/- SD) blood pressure 155.2 +/- 6.5/101.3 +/- 4.8 mmHg], 24 h prior to treatment and 48 h after having received either antihypertensive therapy or placebo; the patients taking part in the study had not taken any antihypertensive treatment 4 weeks prior to the beginning of the trial. After receiving 5 mg ramipril the mean 24-h blood pressure was significantly (P less than 0.05) reduced to 148.3 +/- 5.8/91.5 +/- 5.5 mmHg. After 48 h the blood pressure increased to 153.1 +/- 4.8/96.0 +/- 6.4 mmHg. In the placebo group there was only a slight, non-significant reduction in blood pressure on day 1 (154.3 +/- 6.9/97.3 +/- 5.7 mmHg) and during day 2 the blood pressure increased to 155.4 +/- 5.3/99.5 +/- 5.9 mmHg. The results showed that a once-daily administration of 5 mg ramipril produced a reduction in blood pressure, which lasted 24 h. This simple therapeutic regime offers the advantage of being easy for patients to follow and, therefore, promotes compliance with therapy.

Adult↗
PubMedDate not supplied

Circadian blood pressure rhythms in elderly hypertensive patients.

Blood pressure was recorded for 24 h in 121 essential hypertensive patients aged between 20 and 90 years. To characterize the circadian blood pressure rhythm, the differences between the daytime blood pressures (recorded at 8-min intervals between 8 a.m. and 10 p.m.) and the night-time blood pressures (recorded at 30-min intervals between 10 p.m. and 8 a.m.) were calculated. The difference between daytime and night-time blood pressures was significantly (P less than 0.01) decreased in elderly hypertensive patients aged between 65 and 90 years compared with in those aged 20-39 years. In patients with heart insufficiency the circadian blood pressure rhythmicity was significantly (P less than 0.05) further reduced compared with in uncomplicated hypertensives. This may be explained by increased sympathetic tonus in patients with heart insufficiency and reduced vascular compliance may be the cause of the overall reduced circadian blood pressure rhythmicity in elderly hypertensive patients.

Adult↗
PubMedDate not supplied

Acute hypertension after renal allograft rejection therapy with OKT3 monoclonal antibody.

Acute rejection of renal allografts was treated with the monoclonal antibody OKT3 given intravenously. A variety of adverse events were observed on days 1 and 2 following treatment with 5 mg/day OKT3 for 10 days including heart failure, pulmonary oedema and hypertension. Continuous monitoring of 19 patients treated with OKT3 for acute renal allograft rejection detected a transient increase, lasting 2 h, in systolic and diastolic blood pressures on day 1. A larger increase in systolic and diastolic pressures lasting 11-13 h was observed on day 2. Treatment with 5 mg OKT3 on day 3 did not significantly increase systolic or diastolic pressure. It is concluded that OKT3 can aggravate hypertension and hypertensive emergencies may be encountered during the initial phase of OKT3 treatment.

Acute Disease↗
PubMedDate not supplied

A catheter-based enzyme-coupled electrode for measurement of lactate.

An enzyme-coupled electrode was incorporated into a catheter to measure the concentration of lactate solutions. The sensor output was found to be linearly dependent on the lactate concentration. The average nonlinearity over a sample of nine catheters was 5.88% full scale. Hysteresis for the device was low, with an average of 4.54% full scale. Preliminary results indicate that in-vivo measurements may be possible, which are not possible with other lactate measurement methods.

Biosensing Techniques↗