Adenylate cyclase-cyclic AMP-phosphodiesterase system in microdissected brain areas of normotensive and spontaneously hypertensive rats

The topographical distribution of the adenylate-cyclase-cyclic adenosine monophosphate-phosphodiesterase system was investigated in specific brain areas of rats, and compared with spontaneously hypertensive rats. In normotensive animals, brain cyclic adenosine monophosphate levels were quite uniform (between 7.14 and 13.04 pmol/mg protein) with highest concentrations in catecholamine-containing cell groups. In contrast, the distribution of basal adenylate cyclase and phosphodiesterase activity is not uniform. The unstimulated adenylate cyclase activity was very low in the striatum and catecholamine-containing cell groups in the medulla oblongata (A1C1-cell groups) and very high in the central gray matter and the cerebellum, where the lowest phosphodiesterase activities were measured. In spontaneously hypertensive rats, altered cyclic adenosine monophosphate levels were found in 17 of 36 brain areas investigated in comparison to those of normotensive rats. Increased concentrations were found in regions which are known to participate in the central regulation of blood pressure (nucleus of the solitary tract, A1C1 catecholaminergic cell groups in the ventrolateral medulla oblongata, locus coeruleus) and in the periaqueductal central gray matter, the hippocampus and the cingulate cortex. Lower levels were measured only in hypothalamic nuclei, especially in the paraventricular and dorsomedial nucleus. No significant differences in basal adenylate cyclase activity were found in spontaneously hypertensive rats compared with Wistar-Kyoto control rats, while phosphodiesterase activity was generally higher in spontaneously hypertensive rats, most significantly in the medulla oblongata. Present data show that characterization of the adenylate cyclase-cyclic adenosine monophosphate-phosphodiesterase system helps to localize structural and/or functional differences between the spontaneously hypertensive rat and its normotensive control rat and indicate that more than one functional system is affected in spontaneous hypertension.

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.

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.

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.

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.

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.

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.

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.

[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.

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.

Entorhinal and prepiriform cortices of the European hedgehog. A histochemical and densitometric study based on a comparison between Timm's sulphide silver method and the selenium method

The Timm and selenium staining techniques, based on silver amplification of endogenous zinc, produce an electron-dense precipitate in boutons. The staining characteristics of the two methods were compared by examining two allocortical regions, prepiriform cortex and entorhinal cortex, in the brain of the European hedgehog. In the 3 layers of prepiriform cortex and the 6 layers of entorhinal cortex the methods revealed sublayers, which allows a precise delimitation of areas 28M, 28L, a short transition zone, and the prepiriform cortex. The lamination of the entorhinal cortex of the hedgehog is similar to that found in the rat, but appears less distinct. This may point to a lower degree of afferent organization. For light microscopical investigations, the selenium technique appears superior to Timm's method because it produces a more distinct zonation pattern.

Evidence on the local character of spatial frequency channels in the human visual system

The question has been raised as to whether there exists any transfer of information between neighboring retinal areas following presentation of spatially limited optical stimuli. Our experiments were aimed at mechanisms by which spatial frequency information could be transferred from one part of the visual field to another. Within a 0.9 degree X 2.5 degree section of the 3.6 degree X 2.5 degree testfield the observers adapt to a number of moving sinusoidally-modulated brightness or hue gratings of different spatial frequencies. As known by many publications the sensitivity to spatial frequencies changes in the adapted area. We find that this influence on the contrast threshold decreases as the distance to the adaptation section increases. Hence our results suggest mechanisms within the visual system mathematically best described by a local spectrum analysis.

Freeze-drying and analysis of plant and other biological material

The freeze-drying of biological material, which is to be quantitatively analyzed (micro-amount level) for compounds of low or intermediate molecular weight, should be either omitted or handled under strict control. This is because compounds such as amino acids, sugars, flavonoids, glycosides, coenzymes, peptides, etc., might be removed from concentrates and (or) the ground biological material by the high vacuum.

[Relapse in acute lymphoblastic leukemia of childhood--treatment and results (author's transl)]

Twelve children with their first relapse of acute lymphoblastic leukemia who had the same initial therapy were treated on an out-patient basis. After 28 days all entered second remission. Medium remission duration was 11 months. At the end of the study seven patients were in continuous complete remission. Of the twelve children seven suffered bone marrow, two meningeal, two testicular relapses and one a combined bone marrow and meningeal relapse. Side effects were compatible with an out-patient treatment.

Assessment of adriamycin cardiotoxicity in children by systolic time intervals

In a prospective study, 44 children receiving Adriamycin (ADR) for various neoplastic diseases underwent serial estimations of the systolic time intervals (STI) for the noninvasive assessment of left ventricular myocardial performance. Five of the 44 children developed clinical signs of ADR-related congestive heart failure at a cumulative dose of less than 550 mg/m2 body surface area. Clinical symptoms, changes in the electrocardiogram and in the chest X-ray were preceded in every case by changes of the STI, mainly a prolongation of the left ventricular pre-ejection period (PEP), or a decrease of the ejection time (ET)/pre-ejection period (PEP) ratio (ET/PEP). A continous increase of the PEP and a decrease of the ET/PEP-ratio also gave an indication of myocardial dysfunction during ADR treatment in the other children without clinical signs of congestive heart failure. This subclinical cardiotoxic effect of ADR below the critical cumulative dose of 550 mg/m2 was observed in children with pre-existent myocardial damage, with preceding thoracic irradiation, or during concurrent chemotherapy, of which cyclophosphamide seemed to be most important. Thus, the estimation of the STI proved helpful and reliable in the early detection of incipient heart failure and in the selection of high risk patients in children receiving ADR treatment.