Plasma aldosterone concentrations in chronic renal disease

The disagreement in the literature concerning the role of aldosterone in the maintenance of potassium homeostasis in chronic renal disease might be partially explained by differences in plasma renin activity (PRA) among individual patients. Therefore, a study was done in 28 selected patients with varying degrees of renal insufficiency whose serum potassium and PRA concentrations were within the normal range. The results indicate that at comparable serum potassium and PRA concentrations, plasma aldosterone is in most instances elevated when creatinine clearance is lower than 50% of normal.     

Effect of blockade of angiotensin II on blood pressure, renin and aldosterone in cirrhosis

1-Sar-8-ala angiotensin II (saralasin) was infused intravenously in graded doses of from 0.1 to 10 mug/kg/min to five patients with cirrhosis and ascites after three days of restricted sodium intake. In each patient blockade of AII by saralasin produced a marked fall in blood pressure, a rise in plasma renin activity (PRA) and plasma renin concentration (PRC) and, in four of the five, a fall in plasma aldosterone (PA). The rise in PRA and PRC correlated poorly with changes in blood pressure. The effects of saralasin rapidly reversed after cessation of the infusion. Plasma volume was normal or high in each case. Three patients were mildly hypotensive in the control state, and all five were resistant to the pressor effect of infused AII. After three days of salt loading, the above effects of saralasin were diminished but not abolished. In four normal subjects, after salt depletion, saralasin infusion induced qualitatively similar but much smaller changes in blood pressure, PRA and PRC. In two cirrhotic patients without ascites, after salt depletion, saralasin infusion caused a rise in blood pressure with no significant changes in PRA, PRC or PA. These results provide evidence that in patients with cirrhosis and ascites circulating AII is active in support of blood pressure, in direct suppression of renal renin release, and in stimulation of aldosterone release.     

Effect of bedrest on circadian rhythms of plasma renin, aldosterone, and cortisol

Previous studies of normal men after 5 d of bedrest showed that circulatory instability on head-up tilt or standing is preceded by increased plasma renin activity (PRA) at bedrest. In the present study, the circadian rhythms of PRA, aldosterone, and cortisol have been observed in five normal men on a constant diet. In ambulatory controls, PRA and aldosterone increased normally after standing. On the third morning of bedrest, PRA was higher than before, and at noon, PRA was higher than in standing controls. The nocturnal peaks of PRA resulting from episodic renin secretion during sleep were higher after bedrest. Plasma aldosterone was also increased by bedrest. The findings are compatible with the theory that intermittent beta-adrenergic nerve activity during sleep is increased after bedrest, but other factors, such as loss of body sodium and a lower plasma volume, may also be involved.     

Auto-immunity in certain thyroid diseases

In the years 1971-74, 88 patients were admitted to the Department of Otorhinolaryngology of the Finsen Institute because of thyroid disease. In 37 of these patients, who had also been tested for antibodies against the thyroid, the diagnosis was confirmed histologically. The existence of circulating antibodies against thyroid tissue was found to reflect the degree of lymphocyte infiltration in the thyroid gland, and is thus of significance in the evaluation of the patients' prognosis and potential risk at surgery.     

Plasma renin activity and blood corticosteroids in the Australian lungfish Neoceratodus forsteri

Four developmental stages of Xenopus laevis embryos were fixed in standard electron microscopic fixatives with 1% lanthanum nitrate added. This treatment reveals a lanthanum staining material (LSM) on the cell surface and in extracellular spaces. Morula and blastula stage cells have a small amount of LSM; in blastulae, 3 +/- 3 SD % of the cell surface is coated with LSM. In early gastrulae, 29 +/- 6 SD % of the cell periphery is covered with LSM. In late gastrulae, 82 +/- 13 SD % of the cell periphery is either coated with LSM or faces a space with LSM in it. There is also an appreciable accumulation of LSM within extracellular spaces during gastrulation.     

Antibodies against thyroid gland peroxidase and thyroglobulin in various thyroid diseases

Autoantibodies to thyroperoxidase (anti-TPOAb) and thyroglobulin (anti-TgAb) were measured in 564 patients with various thyroid disorders and in 59 healthy subjects using chemiluminometric immunoassay. The frequency of elevated titers was 8.6% in healthy subjects, 76.2% in patients with untreated hyperthyroidism and diffuse goiter, 80.7% in patients with relapse of hyperthyroidism. 83.4% of patient with hyperfunction changed spontaneously to hypothyroidism and 71.5% of patients with hypothyroidism and goiter had antibodies above the normal range. Unexpectedly low prevalence of autoantibodies were detected in patients with primary myxoedema without goiter (48.2%) and in patients with endocrine ophthalmopathy and euthyroidism (33.2%). In the subgroup of patients with hyperthyroidism under methimazole treatment we found an incidence of positivity of 56% and the mean of positive values was lower compared with the untreated ones. In 42.8% of patients with hyperthyroidism and diffuse goiter treated successfully by methimazole, surgery or radioiodine elevated concentrations of antibodies could be detected, however they were in remission for more than five years. 197 (82.4%) of the patients with positive antibody titers showed higher concentrations to peroxidase compared with thyroglobulin. 57.9% of serum samples positive for anti-TPOAb were negative for anti-TgAb, whereas 9.4% of samples positive for anti-TgAb were anti-TPOAb negative. The diagnosis of thyroid autoimmunity could generally be based on measurement of anti-TPOAb with additional measurement of anti-TgAb in special cases.     

Plasma renin activity in tachistin-stimulated hypercalcemia and under the effect of chlorazine

The aim of the present study was to elucidate the correlation between the Renin secretion and increased Plasma Calcium concentration and the role of Calmodulin in this process. Plasma Renin activity was determined radioimmunologically in 31 white rats, that were grouped as follows: group I - 7 controls loaded for 6 days perorally with 0.5 ml/200 g b.w. glycerin and injected i.m. for 6 days with 0.1 ml/200 g b.w. with 0.9% NaCl; group II - 8 rats, treated for 6 days with Tachistin 0.0025 mg/200 g b.w., dissolved in glycerin 0.5 ml/200 g b.w.; group III - 5 rats, treated with Tachistin 0.005 mg/200 g b.w. in the same manner; group IV - 5 rats injected i.m. with Chlorazin 0.5 mg/200 g b.w. for 6 days; group V - 6 rats, loaded with double dose Tachistin and with Chlorazin 0.5 mg/200 g b.w. for 6 days. Blood samples were taken intracardially on the seventh day from the beginning of the experiment and were analyzed with kits of Sorin-Biomedica-Italy. Our results suggest that the hypercalcemia induced by Tachistin caused a dose-dependent increase of PRA and Ca-Calmodulin complex is the dominant second messenger of Renin secretion.     

Actions of growth hormone-release inhibiting hormone (somatostatin) on the renin aldosterone system

Contractile responses of rings of ductus arteriosus from fetal and neonatal guinea pigs were studied in buffered Krebs-Henseleit solutions of various oxygen tensions. Oxygen-induced contraction of ductus arteriosus increased with gestational age, peaking at term and attenuating within 24 h after birth. Contractions of ductus in response to potassium were not different in term and preterm fetuses. Maximal contractile response of pre- and postductal aortic rings to oxygen was 8.3% of the maximal oxygen-induced contraction of ductal rings from the same fetuses. Pulmonary artery was quite insensitive to oxygen. Of 12 ductus exposed to bradykinin in the absence of oxygen seven contracted (maximal response was obtained with 15.0 ng/ml). Exposure of ductus to bradykinin in the absence of oxygen enhanced subsequent contractions of ductal smooth muscle rings to air. Atropine failed to inhibit the oxygen-induced contraction of ductus. These data suggest that acetylcholine is not essential for oxygen-induced contraction of the guinea pig ductus arteriosus.     

Neuromuscular disorders in thyroid gland diseases

To establish the basis of the interpretative method is congruous with finding a solid basis--epistemologically speaking--to the analytic theory. This basis would be the means to transform this theory into a real science with its necessary adecuation among method, act and object of knowledge. It is only from a scientific stand that the psychoanalytic theory will be able to face successfully the reductionisms that menace it, be it the biologist-naturalism with its explanations of the psychic phenomena by means of mechanisms and biologic models or be it the speculative ideologies with their nucleus of technical praxis which make it impossible for the social-factic sciences to become real sciences. We propose as interpretative method the union of two models: the teleologic one which makes possible the appearance of intelligible, contingent and variable explanations between an antecedent and a consequent on one side, and on the other, the analogic model with its two moments: the comparative and the symbolic one. These moments makes possible the comparison and the union between antecedent and consequent baring in mind the "natural" ambiguity of the subject-object in question. The principal objective of the method--as a regulative idea in the Kantian sense--would be the search of univocity as regards the choice of one and only one sense from all the possible senses that "explain" the motive relationship or motive-end relationship in order to make the interpretation scientific. This status of scientificity should obey the rules of explanation: that the interpretations be derived effectively from the presupposed theory, that they really explain what they claim to explain, that they are not contradictory or contrary in the same ontologic level. We postulate that the synthesis of the two mentioned models, the teleologic-explanative and the analogic one allows us to find a possibility to make clear the "dark" sense of the noun interpretation and in this way the factibility of speaking of an interpretative method that develops the real concrete object by producing the formal and abstract one--which for us is the behaviour of the subject--. In this way the interpretations come to be teleological explanations overdetermined by an analogical relationship. This means that they produce the formal and abstract object -the method--which is in itself an intelligible, continguent and variable relationship between an antecedent and a consequent permitting in this way the emergence of a symbolic comparison to explain the real concrete. The symbolic explanations and comparisons are strictly derived from the presupposed theory, the theoretical body of psychoanalysis.     

Telomerase activity in benign and malignant thyroid diseases

BACKGROUND: Telomerase, an enzyme associated with cellular immortality, is expressed by most malignant cells and is inactive in most normal somatic cells, with the excitation of proliferative stem cells, male germ cells, and activated lymphocytes. The measurement of telomerase activity in clinically obtained tissue samples may provide useful information as both a diagnostic and prognostic marker. In this study, we sought to determine whether telomerase activity might prove helpful in the assessment of benign and malignant thyroid tumors. METHODS: A modified, semiquantitative polymerase chain reaction-based telomeric repeat amplification protocol assay was used for detection of telomerase activity in 59 samples obtained at thyroidectomy, including 15 thyroid cancers, 22 benign thyroid diseases, and 22 adjacent normal thyroid tissues. RESULTS: Four of 13 differentiated thyroid carcinomas (30%) and 2 of 2 medullary carcinomas (100%) expressed telomerase activity. Unexpectedly, we also detected activity in 3 of 22 (14%) adjacent normal thyroid tissues and 6 of 22 (28%) benign thyroid diseases. Pathologic review of the telomerase-positive benign specimens revealed that many contained extensive lymphoid infiltrates with germinal centers (six of nine, 67%), as did two of four telomerase-positive papillary carcinomas. CONCLUSIONS: In contradistinction to other epithelial carcinomas, telomerase does not appear to be frequently reactivated in differentiated thyroid carcinomas.     

Role of tissue renin in the regulation of aldosterone biosynthesis in the adrenal cortex of nephrectomized rats

OBJECTIVE: The conventional surgical treatment of isolated critical stenosis of the left main coronary artery (LMCA) leads to the definitive occlusion of LMCA, restores only a retrograde perfusion to a rather extensive myocardial area and consumes bypass material. Direct surgical angioplasty avoids these inconveniences. METHODS: Between June 1985 and August 1996, 49 surgical angioplasties have been performed in 47 patients. LMCA was approached posteriorly in the first 11 procedures, and an anterior approach was preferred in the last 38 because of better exposure. The onlay patch consisted of saphenous vein in 37 cases; pericardium was used in 12 cases, and only for ostial stenosis. RESULTS: No technical failure occurred in the last 28 cases. 44 procedures, (90%), succeeded, but 1 patient (2.3%) died later of a massive air embolism, and 2 patients needed conventional CABG after 3 and 5 months, respectively. The 35 survivors still benefiting from a successful LMCA angioplasty on the long term are free of ischemia after a mean follow-up of 75 months (2-136). Angiographic restudy was obtained in 30 patients (70%) at an average of 38 months and revealed an excellent result in 26 (87%). In 10 patients, a late angiographic restudy at an average of 71 months (32-119) still revealed a perfect result. CONCLUSION: Provided that well-defined contra-indications (involvement of the distal bifurcation, heavy calcification) are respected, LMCA surgical angioplasty deserves a place in the array of surgical strategies.     

Alterations in plasma volume, plasma constituents, renin activity and aldosterone induced by maximal exercise in the horse

Plasma volume (PV) decreased by 13 per cent following the completion of 1,000 m of maximal exercise in the horse. This study demonstrated that the critical reduction in PV following maximal exercise occurred within 10 mins of completion of exercise, as previously reported in man. Total plasma protein (TPP) increased by 23 per cent at 2 and 5 mins, and by 21 per cent at 10 mins post exercise. Therefore, it does not appear to be an accurate measurement to assess the degree of PV contraction in the horse. Protein was apparently added to the intravascular space either during or following exercise. The changes in osmolality correlated strongly with those in sodium, which is the primary determinant of alterations in plasma tonicity. The increase in osmolality (12 per cent) was similar to the reduction in PV (13 per cent) concluding that a transient hypotonic fluid loss had occurred. The increase in plasma renin activity (PRA) following maximal exercise was followed by an increase in aldosterone (ALD) concentration in both magnitude and time course. Alterations in PV should be considered when interpreting electrolyte and serum enzyme activity data collected following maximal exercise.