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Biomedical subjects

H Geiger

Publications and source records attributed to H Geiger.

At least 109 records · Page 6Linked to original sources
PubMed1989

Does cadmium contribute to the development of renal parenchymal hypertension?

In our study we investigated 36 out-patients with renal disease, 22 of whom were hypertensive. In all patients proteinuria was present (4.30 +/- 5.05 g protein/day) and kidney diseases were verified by renal biopsy. Blood cadmium in non-smokers was significantly (p less than 0.05) lower than in smokers. We found a positive correlation between cadmium-concentration of blood and urine (p less than 0.01, R = 0.44) and between cadmium-concentration of blood and blood uric acid (p less than 0.01, R = 0.44). Proteinuria was weakly correlated with cadmium concentration of urine (p less than 0.05, R = 0.35). Patients with renal hypertension showed a significantly higher (p less than 0.05) urine cadmium excretion per day (1.60 +/- 1.12 micrograms/day) compared to normotensives with a disease of the kidney (1.14 +/- 1.47 micrograms/day). Our results indicate that cadmium may be involved in the development of hypertension in patients with renal disease.

Cadmium↗
PubMed1989

Cadmium and renal hypertension.

In our study we investigated 36 patients with renal disease, 22 of whom were hypertensive. In all proteinuria was present (4.30 +/- 5.05 g protein/day) and renal lesions were proved by renal biopsy. Blood cadmium in non-smokers was significantly (P less than 0.05) lower than in smokers. We found a positive correlation between cadmium concentrations in blood and urine (P less than 0.01, r = 0.44) and between cadmium concentration in blood and serum uric acid levels (P less than 0.01, r = 0.44). Proteinuria was weakly correlated with cadmium concentration in urine (P less than 0.05, r = 0.35). Patients with hypertension showed a significantly higher (P less than 0.05) urine cadmium excretion per day (1.60 +/- 1.12 micrograms/day compared with normotensives with disease of the kidney (1.14 +/- 1.47 micrograms/day). Our results indicate that cadmium may be involved in the development of hypertension in patients with renal disease.

Cadmium↗
PubMed1989

Role of cadmium in hypertensive patients with renal parenchymal disease.

In our study we investigated 36 out-patients with renal disease; 22 of them were hypertensive. In all patients proteinuria was present (4.30 +/- 0.82 g protein/d) and renal involvement has been proved by renal biopsy. Blood cadmium in nonsmokers was significantly (P less than .05) lower than in smokers. Patients with renal hypertension showed a significantly higher (P less than .05) urine cadmium excretion/d (1.60 +/- 0.23 micrograms/d) compared to normotensives with a disease of the kidney (1.14 +/- 0.38 micrograms/d). Our results indicate that cadmium may be involved in the development of hypertension in patients with renal disease.

Cadmium↗
PubMed1989

Improved sexual function in hemodialysis patients on recombinant erythropoietin: a possible role for prolactin.

As it was reported that correction of anemia in long-term hemodialysis patients by recombinant human erythropoietin (r-HuEPO) is associated with improved sexual function, we conducted the present study to further delineate the mechanism(s) by which this is brought about. Serum prolactin, testosterone, and parathyroid hormone (PTH) levels were followed during 4 months of r-HuEPO therapy. Within 4 months of treatment with r-HuEPO, hematocrit values rose from 23.7 +/- 1.2 to 35.7 +/- 0.2% and hemoglobin increased from 7.3 +/- 0.3 to 11.3 +/- 0.4 g/100 ml. In parallel, serum prolactin values decreased significantly from 66.9 +/- 9.3 to 9.6 +/- 2.6 ng/ml in females and from 39.5 +/- 10.5 to 10.3 +/- 1.0 ng/ml in male dialysis patients. Testosterone concentrations were low in male patients and remained unchanged during r-HuEPO therapy. Baseline PTH values were elevated (1,880 +/- 220 pg/ml) in patients of both sexes and declined to 1,410 +/- 180 pg/ml during treatment with r-HuEPO. However, this difference did not reach statistical significance. Sexual function improved in 4 out of 7 males and 5 out of 9 female patients began to menstruate regularly again. It appears that treatment of anemia in end-stage renal disease by r-HuEPO improves sexual function via normalization of elevated serum prolactin concentrations.

Adult↗
PubMed1988

Glandular adenylate cyclase system in genetic hypertension: age-dependent response to catecholamines.

The parotid excretion of cAMP was measured in normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) in this study. In addition, adenylate cyclase activity in parotid gland tissue was determined. The cAMP excretion rate was increased immediately after isoproterenol infusion. This elevation was more pronounced in young (6-8 weeks) than in older (16-18 weeks) animals, both in WKY and in SHR. These data demonstrate a diminished cAMP response to isoproterenol application with respect to the age of the animals. This could indicate that there is an age-dependent functional alteration of the beta-adrenoceptor-adenylate cyclase complex. In agreement with the results of these in vivo studies, the stimulation of adenylate cyclase activity of the parotid gland by isoproterenol or fluoride was enhanced in young SHR and lowered in old SHR when compared to their normotensive controls of the same age. One may conclude that the sympathetic activity is enhanced in young SHR, and that the beta-adrenoceptor system is hypersensitive to adrenoceptor agonists. This might contribute to the development of hypertension in SHR. Sixteen to eighteen weeks old SHR showed a diminished cAMP output following isoproterenol application when compared to normotensive control rats of the same age. The reduction of the response to isoproterenol stimulation in old SHR seems to be related to a reduced sensitivity to catecholamine stimulation.

Adenylyl Cyclases↗
PubMed1988

Atrial natriuretic factor in specific brain areas of spontaneously hypertensive rats.

Atrial natriuretic peptides (atrial natriuretic factor, ANF) are present in a great number of brain areas inside and outside of the blood-brain barrier. The pattern of distribution implies the involvement of ANF in different physiological functions, such as blood pressure regulation, electrolyte and fluid homeostasis, and modulation of the neuroendocrine system. To further investigate a possible involvement of central ANF in spontaneous hypertension, we measured levels of ANF in 18 selected, microdissected brain areas of prehypertensive (4-week-old) and hypertensive (12-week-old) spontaneously hypertensive rats (SHR) and their normotensive control, Wistar-Kyoto rats (WKY), by radio-immunoassay. ANF was significantly decreased in seven brain areas in SHR at both ages investigated; the most pronounced decreases were found in the subfornical organ, in the perifornical and periventricular hypothalamic nuclei, and in the medial preoptic nucleus. In addition, in young SHR ANF was significantly decreased in the organum vasculosum laminae terminalis and increased in the median eminence. After the development of hypertension, a significant decrease of ANF could be detected in four more brain areas (bed nucleus of the stria terminalis, paraventricular and arcuate nuclei, dorsal raphe nucleus) of SHR, as compared with normotensive controls, and the increase in the median eminence was no longer detectable. These results suggest a role for ANF in genetic hypertension and the specific importance of certain brain regions.

Animals↗
PubMed1987

Prostacyclin (PGI2) induces rapid depletion of cyclic AMP levels in brain nuclei of rats.

Intravenous injection of prostacyclin (100 micrograms/kg) in rats resulted in a decrease of systolic blood pressure within 2 minutes. Concentrations of cAMP in 15 brain regions and nuclei were determined by radioimmunoassay. In lower brain stem nuclei, such as the nucleus of the solitary tract and the lateral reticular nucleus (A1 and C1 catecholaminergic cell groups) cAMP levels were depleted significantly, while in others, including the locus coeruleus and the periaqueductal central gray, cAMP levels did not show any alterations. Levels of cAMP were also depleted in some of the hypothalamic nuclei (periventricular, anterior hypothalamic, ventromedial), and in cerebral cortical areas. Lowered cAMP levels in brain areas might indicate lower cellular activity in cells participating in baroreceptor control mechanisms.

Animals↗
PubMed1987

Alterations in the adenylate cyclase-cAMP-phosphodiesterase system in the locus coeruleus during the development of spontaneous hypertension of the rat.

The quantitatively most important noradrenergic cell group of the brain is the locus coeruleus. Significantly increased cAMP concentration could be measured in spontaneously hypertensive rats in comparison to normotensive Wistar-Kyoto control rats at every stage investigated. Furthermore, both the basal activity and maximal stimulation of Ca++- and GTP-dependent adenylate cyclase as well as phosphodiesterase activity were significantly decreased in the spontaneously hypertensive rats at 14 weeks of age. The possible role of the locus coeruleus in spontaneous hypertension is presumed in counterregulatory mechanisms against rising blood pressure.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1987

A self-organizing neural network sharing features of the mammalian visual system.

This paper describes a neural network model whose structure is designed to closely fit neuroanatomical and -physiological data, and not to be most suitable for rigorous mathematical analysis. It is shown by computer simulation that a process of self-organization that departs from a fixed retinotopic order at peripheral layers and includes Hebbian modifications of synaptic connectivity at higher processing levels leads to a system that is capable of mimicking various functions of visual systems: In the initial state the overall structure of the network is preset, individual connections at higher levels are randomly selected and their strength is initialized with random numbers. For this model the outcome of the self-organization process is determined by the stimulation during the developmental phase. Depending on the type of stimuli used the model can either develop towards a feature-selective "preprocessor" stage in a complex vision system or towards a subsystem for associative recall of abstract patterns. This flexibility supports the hypothesis that the principles embodied are rather universal and can account for the development of various nervous system structures.

Animals↗
PubMed1987

A strategy for testing established human plasma protein manufacturing procedures for their ability to inactivate or eliminate human immunodeficiency virus.

The manufacturing procedures used for the preparation of human plasma proteins that were established before AIDS was first described may reasonably be expected to provide AIDS safe products. Such manufacturing procedures are heat treatment at 60 degrees C in solution for ten hours, described as pasteurization, preparation of human immunoglobulins by ethanol precipitation, pepsin treatment, and sulfonation. To test whether these methods effectively inactivated and/or eliminated the AIDS causing human immunodeficiency virus (HIV), nine volumes or more of plasma or a plasma fraction taken from a production lot were spiked with HIV using one volume of a HIV concentrate and were then subjected to exactly the same procedure as that specified for the manufacturing process. HIV infectivity titres of the initial HIV/plasma protein mixtures and of the resulting products after treatment were determined by the H9 cell assay. In all cases studied complete inactivation/elimination of the added HIV was achieved. We therefore conclude that pasteurization of human plasma proteins or the manufacturing procedure used for the isolation of immunoglobulins from plasma pools result in final products which do not contain any infectious HIV and which are thus safe in that they cannot be vehicles for the transmission of AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Effect of angiotensin-converting enzyme inhibitors captopril and enalapril on cAMP content of specific brain areas in spontaneously hypertensive rats.

1. The influence of two angiotensin-converting enzyme inhibitors, captopril and enalapril, on the cAMP content of microdissected brain areas was examined in spontaneously hypertensive rats. Both drugs depleted systolic arterial blood pressure significantly. 2. Captopril and enalapril increased the level of cAMP in catecholaminergic cell groups in the lower brain-stem. Captopril was more effective in the substantia nigra, while enalapril treatment resulted in high cAMP levels in the ventrolateral medulla oblongata (A1 catecholaminergic cell group). 3. Both drugs, especially captopril, depleted cAMP content in the cingulate cortex. 4. No changes in cAMP levels were measured in the primary baroreceptor centre (nucleus of the solitary tract) following either captopril or enalapril treatment.

Animals↗
PubMed1986

Participation of various brain nuclei in the altered time course of genetic hypertension in SHR dependent on changes in calcium metabolism.

Variations in calcium alimentation influence the development of high blood pressure in genetic hypertensive rats. Different calcium feeding and changes in parathyroid hormone status cause altered cAMP-content in specific brain areas. All animals with high calcium diet show significant elevated cAMP-content in the locus coeruleus, irrespective of parathyroid status. These findings support the hypothesis that elevated cAMP-concentrations reflect an increased depressor activity of the locus coeruleus.

Animals↗
PubMed1986

[Modern methods for the manufacture of therapeutic coagulation factors].

In a modern therapy concept coagulation factor concentrates are widely used for prophylaxis of bleeding events and in intensive care medicine. In the past their use was limited by the risk of transmitting virus diseases to the patient. Therefore, it was a challenge to modern plasma fractionation to develop purification processes which are able to eliminate and inactivate viruses. At present several methods for virus inactivation are used; their efficiency is not finally proven. Practical experience exists with a method in which viruses are inactivated by heat treatment in solution. A similar process is used since more than 40 years to produce albumin and was proven to be safe. Today, all coagulation factor preparations can be treated by this inactivation method and produced in large scale. Together with a high degree of viruses elimination during the purification process the therapy with coagulation factors has become much safer.

Antithrombin III↗