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Biomedical subjects

D Heck

Publications and source records attributed to D Heck.

35 records · Page 2Linked to original sources
PubMed1991

Calcification of aortic wall in cholesterol-fed rabbits.

Development of the mineralization process in the course of atherogenesis was studied using the cholesterol-fed rabbit model. The aorta samples were investigated by means of proton and electron microprobes, infrared spectroscopy and X-ray diffraction as well as selected histochemical staining. Blood serum was analysed every 2 weeks to determine the content of cholesterol, triglycerides, inorganic phosphorus, ionized calcium, elemental composition as well as activity of alkaline phosphatase. It was found that the administered diet did not disturb the calcium and phosphorus homeostasis. Histochemical findings confirmed the formation of lipid-rich lesions blocking the lumen of the vessel. The dystrophic calcification was observed only in the atheroma, while in the tunica media a slight mineralization similar to that found in controls was observed after 210 days of the diet. In the atheroma the only phase detected was a defective hydroxyapatite. The perfection of the crystals, as well as the diameter of the deposits, increased during the course of the diet reaching about 2 microns after 210 days. The crystals were not contaminated with carbonate groups regardless of the duration of the diet.

Animals↗
PubMed1991

Evaluation of the Ca2+ distribution in aortic tissue of spontaneously hypertensive and normotensive rats.

In the present study, particle-induced X-ray emission (PIXE) was used to get information on the spatial distribution of Ca2+ in aortas of spontaneously hypertensive rats (SHR) and normotensive controls aged 1 week, 4 weeks, and 12 weeks. To differentiate changes in Ca2+ metabolism in hypertensive arteries from secondary phenomena due to the arteriosclerosis, the animals were examined in the earliest stage of hypertension. It was found that the Ca2+ content was not elevated in the aortic smooth muscle of SHR aged 1 week (n = 11), as compared to normotensive controls (n = 10) (186.8 +/- 89.9 micrograms Ca2+/g tissue v 254.0 +/- 173.3 micrograms Ca2+/g). The Ca2+ content was raised (P less than .05) in the aortic smooth muscle of SHR aged 4 weeks (n = 13), as compared to 12 WKY rats (4 weeks) (726.0 +/- 130.4 micrograms Ca2+/g tissue v 440.3 +/- 214.4 micrograms Ca2+/g) and in 17 SHR (3 months), as compared to 13 WKY rats, respectively (3390.1 +/- 729.9 micrograms Ca2+/g tissue v 1632.1 +/- 569.5 micrograms Ca2+/g). The results confirm the age-related increase in the arterial Ca2+ content in normotensive rats and demonstrate additionally that this age-related rise in arterial Ca2+ content is accelerated in SHR.

Animals↗
PubMed1991

Anterior (cranial) cruciate ligament transection in the dog: a bona fide model of osteoarthritis, not merely of cartilage injury and repair.

To help elucidate the longterm outcome in the unstable knees of dogs that have undergone anterior cruciate ligament (ACL) transection, conventional radiography, gait analysis and magnetic resonance imaging (MRI) were performed serially on 3 dogs over a 45-month period after ACL transection. Gait analysis showed that vertical forces generated by the cruciate deficient leg were smaller than those produced by the contralateral leg, but the decrease in loading was not progressive and clinical findings did not suggest that the dogs developed pain in the unstable limb. Despite progressive osteophytosis and subchondral sclerosis, as seen on plain radiographs, MRI demonstrated that articular cartilage in the unstable knee was thicker than that in the contralateral knee 36 months after ACL transection. Nine months later, however, striking focal loss of articular cartilage was seen in the unstable knee of each dog. Our study, which provides the first longterm observations of the changes in the unstable knee after ACL transection, shows that they represent progressive osteoarthritis and emphasizes that a prolonged phase of cartilage hypertrophy may precede the stage of cartilage breakdown.

Animals↗
PubMed1988

Age-dependent increase in arterial smooth muscle calcium in spontaneously hypertensive rats.

Alterations in cellular calcium metabolism in essential hypertensive and in the SHR have been described. In the present study, particle-induced X-ray emission (PIXE) was used to get some information on the spatial distribution of Ca2+ in aortas of spontaneously hypertensive rats (SHR) and normotensive controls aged 1 week, 4 weeks, and 12 weeks. It was found that the Ca2+ content was not elevated in the aortic smooth muscle of SHR aged 1 week (n = 9) as compared to normotensive controls (n = 8) (186.8 +/- 89.9 micrograms Ca2+/g tissue vs 254.0 +/- 73.7 micrograms Ca2+/g tissue. The Ca2+ content was significantly raised in the aortic smooth muscle of SHR aged 4 weeks (n = 9) as compared to 4-weeks-old WKY rats (n = 12) (726.0 +/- 130.4 Ca2+/g tissue vs 440.3 +/- 214.4 Ca2+ micrograms/g tissue and in SHR aged 3 months (n = 15) as compared to WKY rats (n = 12), respectively (3317.0 +/- 734.0 micrograms Ca2+/g tissue vs. 1632.0 +/- 569.6 micrograms Ca2+/g tissue). The results confirm the age-related increase in the arterial Ca2+ content in normotensive rats and demonstrate additionally that this age-related rise in arterial Ca2+ content is accelerated in SHR.

Aging↗
PubMed1988

Investigation of inorganic deposits in selected organic matrices.

Inorganic deposits in the wall of human and animal arteries and in experimental tumor (Morris hepatoma 7777) were examined using proton induced X-ray emission (PIXE) and PIXE in combination with proton microprobe (micro-PIXE) techniques. The sections adjacent to the irradiated ones part were submitted to histological investigations and one part of the material was additionally investigated by infrared (IR) spectroscopy. For identification of mineral deposits, the micro-PIXE method appeared the most sensitive. The mineral deposits were detected in the artery samples, even in those without visible morphological changes, as well as in tumor samples. The deposites showed different localization and composition, depending on age and type of vessel. There were also differences between human and animal arteries. IR spectroscopy revealed the presence of carbonate apatite within the artery samples from old individuals. Matching of histological observations with data obtained by micro-PIXE method allows a better correlation of morphological and analytical results.

Animals↗
PubMed1988

Analysis of Ca2+ in aortic tissue: age-dependent Ca2+ content in spontaneously hypertensive rats and in normotensive controls.

In the present study particle-induced X-ray emission (PIXE) was used to analyse the spatial distribution of Ca2+ in aortic tissue of spontaneously hypertensive rats (SHR) and normotensive controls aged 1 week, 4 weeks and 12 weeks. Ca2+ was not elevated in the aortic smooth muscle of SHR aged 1 week (n = 9) compared with normotensive controls (n = 8; 186.8 +/- 89.9 micrograms Ca2+/g tissue). Ca2+ was significantly increased in the aortic smooth muscle of SHR aged 4 weeks (n = 9) compared with 4-week-old Wistar-Kyoto (WKY) rats (n = 12; 726.0 +/- 130.4 micrograms Ca2+/g tissue versus 440.3 +/- 214.4 micrograms Ca2+/g tissue) and in SHR aged 3 months (n = 15) compared with WKY (n = 12), (3317.0 +/- 734.0 tissue versus 1632.0 +/- 569.6 micrograms Ca2+/g tissue, respectively). The results confirm an age-related increase in arterial Ca2+ in normotensive rats and demonstrate that this age-related rise is accelerated in SHR.

Animals↗
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

Elemental composition of the human atherosclerotic artery wall.

The elemental composition of the human atherosclerotic popliteal artery was examined using the proton-induced X-ray-emission (PIXE) method. The application of a narrow proton beam (3 X 10 micron 2) enabled us to determine not only the concentrations of Cl, K, Ca, Fe, Cu, Zn, Br and Pb, but also their localization in different artery-wall regions. The highest mean concentrations of Cl, K, Zn and Br were found in the tunica media. In the investigated sections the distribution of Ca and Fe varied: sometimes, these elements were prevalent in the tunica intima, whereas in other cases, the highest concentrations were observed in the tunica media or tunica adventitia. The concentration profiles of each element were characterized by many sharp, narrow peaks. The highest concentrations of Ca and Fe showed such high levels that only one explanation is possible, i.e. the presence of crystals. The correlation of Ca peaks with those of Zn and Fe is discussed. The usefulness of the micro-PIXE method for the investigation of biomedical materials is also considered.

Aged↗
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

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

Physicochemical characterization of the inorganic phases in the aortic wall of young individuals.

The autopsy samples of human aortic wall were investigated to determine the structure of the inorganic deposits formed at the onset of the mineralization process. The studies were concentrated on the material for which histochemical staining of randomly selected sections did not reveal the presence of minerals. The highly mineralized human media samples as well as broad spectrum of model compounds were investigated for comparative purposes. It was found that the inorganic phase at the onset of tunica media mineralization is composed of a few compounds including octacalcium phosphate as the predominant Ca-P compound, and a Mg-compound, probably magnesium carbonate or double/triple salts containing magnesium carbonate.

Adolescent↗
PubMedDate not supplied

Artery wall calcification: correlation of atherosclerosis with mineralization.

Popliteal arteries from 14 individuals (17-85 y old) were investigated. The concentrations and localizations of P, S, Cl, K, Ca, Fe, Cu, Zn and Br were measured by means of PIXE and micro-PIXE methods. The presence of PO4(3-) and CO3(2-) groups was assessed using the IR technique. The amount of P and Ca increased with age approaching at places 9% and 20% and mineral deposits were detected in tunica media. At the same time an increase in the Ca/P ratio and in the crystallinity of deposits was observed. The samples from old individuals also contained more CO3(2-) groups. The concentrations and localization of Zn and Br showed artery wall layer-dependent changes. In some places of the artery wall, minerals were also found in young persons. They were not correlated with places of blood vessel branching.

Adolescent↗