Effects of Asp-179 mutations in TEMpUC19 beta-lactamase on susceptibility to beta-lactams

To examine the effect of disruption of the salt bridge (between Arg-164 and Asp-179 [numbering of Ambler et al. (Biochem J. 267:269-272, 1991)]) that anchors the conserved omega-loop in class A beta-lactamases, we obtained mutant enzymes with each of the 19 other amino acid residues replacing Asp-179 in the TEM beta-lactamase encoded by pUC19 and studied the level of resistance to various beta-lactams conferred by each enzyme. All mutations of Asp-179 compromised the level of resistance to ampicillin, but most of them enhanced resistance to ceftazidime. In contrast, mutations of Asp-179 generally impaired the low levels of resistance to cefepime and aztreonam. One might expect to find clinical isolates with mutant TEM beta-lactamases with replacements of Asp-179 that express an expanded spectrum of resistance to beta-lactams including ceftazidime.

Effect of chlorpromazine on the synthesis of neutral lipids and phospholipids from [3H]glycerol in the primordial human placenta

Addition of chlorpromazine (CPZ) of 100 microM final concentration to fragments of primordial human placenta incubated in vitro with [3H]glycerol results in the following changes in the labelling of various neutral lipids and phospholipids: (1) rapid accumulation of [3H]phosphatidic acid (PA) to a 2.31 +/- 0.12-fold (mean +/- s.d., P < 0.05) higher steady-state level within 5 min; (2) a dramatic, 5-6-fold (5.74 +/- 0.31, P < 0.01) increase in [3H]phosphatidylinositol (PI) synthesis within 5-10 min, followed by progressive PI accumulation; (3) gradual accumulation of [3H]1,2-diacylglycerol (DAG) reaching approximately 1.7-fold (1.72 +/- 0.14, P < 0.05) higher steady-state level at 30 min; and (4) an approximately 20 and 30% decrease in [3H]triacylglycerol (TG) and [3H]phosphatidylcholine (PC) formation, respectively, which begins to become evident between 10-30 min. As dose-response studies indicate, accumulations of PI and DAG are most susceptible to CPZ. They respond in the concentration range of 10-50 microM, while only higher drug concentrations (100-250 microM) affect the synthesis of PA, PC and TG significantly. Finally, dioctanoylethyleneglycol (DOEG), a structural analogue of the diacyl moiety of PA and DAG, selectively inhibits the basal synthesis (0.59 +/- 0.15, P < 0.05) as well as the CPZ-induced rise (0.49 +/- 0.11, P < 0.02) of PI. These results suggest that CPZ-induced increase in the concentrations of PI and 1,2-DAG may interfere with signal-transduction pathways in the placenta of pregnant patients treated with CPZ. Furthermore, DOEG is able to antagonize the CPZ effect which directs lipid biosynthesis towards the formation of PI.

[Thyroid-stimulating hormone-secreting pituitary adenoma]

A 40-year-old male patient with a 2 years history of recurring hyperthyroidism is presented with clinical hyperthyroidism and diffuse goiter. Despite thyreostatic treatment and surgical thyroid ablation the hyperthyroidism recurred. The patient had laboratory evidence of hyperthyroidism and his serum TSH was persistently and enormously elevated (T4:214 nmol/l, T3:6.9 nmol/l, TSH:218 mIU/l)> Computed tomography and magnetic resonance imaging confirmed a pituitary mass of 7 cm in a-p diameter, with supra-, parasellar and sphenoidal extension. The pituitary adenoma was partially resected by transsphenoidal surgery, which failed to result in a substantial decrease in the serum thyrotropin level. Pituitary irradiation and a long-term somatostatin analog octreotide treatment (300-600 micrograms/die) combined with bromocriptine therapy resulted in a significant, but still incomplete suppression of thyrotropin secretion (TSH level about 15 mIU/l) and persisting mild hyperthyroidism. The size of the adenoma was unchanged during the two years of highdose octreotide treatment period. According to our best knowledge this is the first reported case of a thyrotropin-secreting pituitary adenoma in Hungary.

Pheromonal Production of and Response to Optically Active Epoxydienes in Some Geometrid Moths (Lepidoptera: Geometridae)

In pheromone extracts of calling female Chiasma clathrata L. (Lepidoptera: Geometridae), a defoliator pest of alfalfa, (Z,Z,Z)-3,6,9-heptadecatriene and (Z,Z)-6,9-cis-3,4-epoxyheptadecadiene was identified. Chiral gas chromatography using a modified cyclodextrin and synthetic reference samples proved the natural epoxide to show (3R, 4S)-configuration. In field trapping tests, only the pure (3R, 4S)-enantiom er of the epoxide attracted males. The addition of the triene component was synergistic. Males of the sympatric species Tephrina arenacearia Hbn. (Lepidoptera: Geometridae) were caught only in traps with baits containing the (3S, 4R)-enantiomer [together with a previously described minor component, (Z,Z)-3,9-cis- 6,7-epoxyheptadecadiene]. In trapping tests conducted in a different biotope, Abraxas grossulariata L. (Lepidoptera: Geometridae) males were attracted by the (3S, 4R)-enantiomer, whereas the (3R, 4S)-enantiomer attracted a close relative, Abraxas sylvata Scop. (Lepidoptera: Geometridae). The present results suggest that one of the key mechanisms responsible for pheromone specificity among both the two alfalfa geometrids and the two A braxas species in their respective biotops, may be the use of different enantiomers of the same polyenederived epoxide as a sex pheromone component. It is probable that this discrimination mechanism is widespread among moth species utilizing epoxide pheromone components

Effects of genistein on cardiac contractile force and atrial natriuretic peptide secretion in the isolated perfused rat heart

We examined the effects of a selective protein tyrosine kinase inhibitor, the isoflavonoid genistein, on haemodynamics and atrial natriuretic peptide (ANP) secretion in perfused rat heart preparations. The addition of genistein into the perfusion fluid at concentrations of 11, 22 and 37 microM for 30 min in the spontaneously beating rat hearts caused dose-dependent, sustained increases in contractile force, perfusion pressure and immunoreactive ANP secretion, while heart rate remained constant. The positive inotropic and vasoconstrictor effects of genistein were significantly (P < 0.001) greater in the paced than in spontaneously beating rat hearts. Infusion of the calcium-channel antagonist diltiazem (3 microM) inhibited the genistein-induced positive inotropic effect by 52% (P < 0.001), and KN-62 (1.5 microM), an inhibitor of Ca2+/calmodulin-dependent protein kinase II, by 34% (P < 0.001). The genistein-induced increase in immunoreactive ANP secretion was completely blocked by diltiazem (P < 0.001) while KN-62 delayed (P < 0.02) the increase of immunoreactive ANP concentration in the perfusate. These results show that genistein, at concentrations known to inhibit the activities of protein tyrosine kinases, dose-dependently increased contractile force, coronary vascular tone and ANP secretion from isolated perfused rat hearts. These cardiac effects of genistein may be mediated by elevation of intracellular Ca2+ concentration, as shown by the inhibition of inotropic and secretory effects by both L-type calcium channel antagonist and Ca2+/calmodulin-dependent protein kinase inhibitor.

Hypoxia stimulates release of ANP and BNP from perfused rat ventricular myocardium

We determined the effect of hypoxia on cellular energy state and ventricular atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and endothelin-1 (ET-1) release in an isolated perfused heart preparation after removal of all atrial tissue in 21- to 24-mo-old Wistar-Kyoto rats. After a control period (14 min), the ventricles (n = 6) were exposed to 30 min of hypoxia by changing the gas mixture to N2-CO2 (95:5 vol/vol; hypoxic period) and back to O2-CO2 (95:5 vol/vol) for 30 min (reoxygenation period). Control hearts (n = 6) were perfused throughout the experiment (74 min) with oxygenated Krebs-Henseleit phosphate-free buffer. In parallel experiments, the metabolic state of oxygenated (n = 4) and hypoxic (n = 5) ventricles was assessed using 31P-nuclear magnetic resonance (31P-NMR). Hypoxia caused a rapid decrease in left ventricular peak systolic pressure associated with a 2.1-fold increase (27.6 +/- 2.2 to 58.0 +/- 13.1 fmol/ml; P < 0.05) in the concentration of immunoreactive (ir) ANP and a 1.6-fold increase (2.5 +/- 0.2 to 3.9 +/- 0.5 fmol/ml; P < 0.05) in the [irBNP] (where brackets signify concentration) in the perfusate. In contrast, perfusate [irET-1] (1.2 +/- 0.2 fmol/ml) did not change significantly during hypoxia. 31P-NMR showed that the [ATP]-to-[ADP].[Pi] ratio was reduced during hypoxia with a simultaneous increase in intracellular monophosphates and perfusate [irANP] and [irBNP]. The decrease in the cytosolic pH during hypoxia was small. High-performance liquid chromatography of the perfusates showed that the ANP-like immunoreactive material released corresponded to the processed, low-molecular weight peptide.(ABSTRACT TRUNCATED AT 250 WORDS)

Attenuation of diacylglycerol signal in the primordial human placenta: role of phosphatidylcholine formation

Metabolic conversion of the synthetic DAG, dioctanoylglycerol (DOCG) into the dioctanoyl species of phosphatidic acid (PADOCG) and phosphatidylcholine (PCDOCG) in minced human primordial placenta incubated with [32P]phosphate was studied. Time-course experiments performed with 0.25 mM DOCG revealed a much higher capacity of the placenta to synthetize PCDOCG than PADOCG and indicated the rapid metabolism of PCDOCG. In addition, DOCG stimulated the labeling of PC whereas no such effects on the labeling of lyso-PC and PA were observed. This effect of DOCG is not related to the synthesis of PC de novo, because DOCG did not exhibit any stimulating effect on the synthesis of PC from [3H]glycerol or [3H]glucose. Experiments with varying concentrations of DOCG (0.025-0.5 mM) showed increasing rate of formation of PCDOCG over a concentration range from 0.05 to 0.5 mM whereas 0.5 mM DOCG was the lowest concentration where significant formation of PADOCG was found. Labeling of PC was about 30% over control at 0.125 mM as well as at 0.25 mM DOCG, and decreased below the control level at 0.5 mM DOCG. Labeling of PA and PI was not influenced by these DOCG concentrations. Labeling of PC, either stimulated by DOCG or not, was more sensitive to the inhibitory effect of 1 mM of the DAG analog: dioctanoylethyleneglycol (DOEG) than that of PA. Moreover, 1 mM DOEG inhibited the formation of PCDOCG without such an effect on the labeling of PADOCG. These findings indicate that in the primordial human placenta PC synthesis represents a more efficient attenuation pathway of DAG signal than the formation of PA by DAG kinase.

[Multiple endocrine neoplasia]

The authors review present knowledge on multiple endocrine neoplasias types 1 and 2. They discuss in the light of recent literature data, the natural history, diagnosis, differential diagnosis and the optimal diagnostic approaches of these disorders. A short review on the therapeutic modalities draws attention to important differences between sporadic and inherited endocrine tumors. Finally, the authors emphasize recent developments about the genetic background and the importance of molecular biologic techniques, including family screening in the diagnosis of these disorders.

Adenosine inhibits the release of atrial natriuretic peptide from the perfused rat heart

The effect of adenosine on atrial natriuretic peptide (ANP) release was studied in the perfused rat heart model. Adenosine had no effect on the heart rate of the spontaneously beating heart at a concentration of 1 microM, whereas at concentrations of 10 and 100 microM it dose-dependently decreased the frequency by 17 and 55% (P < 0.05 and P < 0.001, respectively). In the spontaneously beating hearts, immunoreactive ANP release was inhibited by adenosine at concentrations of 10 and 100 microM (P < 0.05 and P < 0.01). When heart rate was maintained constant by external pacing, inhibition of ANP release was observed only with 100 microM adenosine (P < 0.01). The results show that adenosine dose-dependently inhibits ANP release from the perfused rat heart. The effect of adenosine on ANP release was partially due to its negative chronotropic effect but the results suggest that adenosine may also have a direct inhibitory effect on ANP release in atrial myocardium.

[Flow-cytometric study of the DNA content in adrenal cortex tumors]

Flow cytometric deoxyribonucleic acid measurements were performed on 26 adrenocortical tumours and 9 non-tumours adrenals. All but one tumours were classified both histologically and clinically as benign, however, two thirds of them had abnormal deoxyribonucleic acid stemlines. Proliferative indices of adenomatous tissues were significantly higher than those of non-tumorous adrenals (p < 0.01). When compared to tumors smaller than 5 cm in size, tumours larger than 5 cm displayed significantly higher proliferative indices (p < 0.01). Thus, flow cytometry appears to have only a limited value in distinguishing between benign and malignant adrenocortical tumours, but it may provide additional information about the prognosis of these tumours.

Mineralocorticoid production of adrenal cortical adenomas

We studied in vitro and in vivo corticosteroid production as well as the presence of symptoms of an increased mineralocorticoid effect in patients with 'silent' adrenal cortical adenomas, and compared these results to those found in patients with classical mineralocorticoid excess syndromes. We found that under in vitro conditions, cells from 'silent' adrenal cortical adenomas (n = 19) produced substantial amounts of both zona glomerulosa and fasciculata steroids, although the production of steroids in these cells was lower compared to that in mineralocorticoid-producing adenoma cells (n = 26). Patients with aldosterone-producing and 'silent' adenomas had significantly increased plasma atrial natriuretic peptide levels, which remained non-suppressible after upright posture and furosemide administration. Of the 25 patients with 'silent' adenomas, 11 had low and non-stimulable plasma renin activity (PRA) before but, in most cases, not after adrenal surgery. When compared to those with normal PRA (n = 14), patients with low PRA 'silent' adenomas (n = 11) had higher blood pressure which was significantly reduced after surgery, and a mild hypokalemia before but not after surgery. Although basal plasma concentrations of aldosterone, 18-hydroxy-corticosterone, corticosterone, deoxycorticosterone, 18-hydroxy-DOC, cortisol,11-deoxycortisol and 17-hydroxy-progesterone (17-OH-P) were not increased in either groups of 'silent' adenomas, ACTH stimulation produced a hyperreactive response for all measured steroids, of which an extremely high 17-OH-P seemed to be one of the most intriguing findings. We consider that these observations in 'silent' adrenal cortical adenomas may justify surgical intervention, irrespective of the size and potential malignancy of these adenomas.

Direct inhibitory effect of etomidate on corticosteroid secretion in human pathologic adrenocortical cells

Etomidate has been shown to inhibit corticosteroid secretion in the normal adrenal gland, but its direct effect in human pathologic adrenals has not been clearly established. In the present study the effect of varying doses of etomidate (10(-11)-10(-5) M) was investigated on basal and adrenocorticotrophic hormone (ACTH)-stimulated corticosteroid secretions in isolated adrenocortical cells obtained from two patients with primary aldosteronism (adenoma and micronodular hyperplasia) and in those from a patient with Cushing's syndrome (adenoma). In cells from primary aldosteronism, increasing concentrations of etomidate (10(-11)-10(-5) M) produced a dose-dependent decrease of basal and ACTH-stimulated cortisol, aldosterone, 18-hydroxycorticosterone, and corticosterone secretions (ED50: 10(-9)-10(-8) M for each of these corticosteroids). In the same cells, the secretions of 11-deoxycortisol and deoxycorticosterone were increased in the presence of low (10(-9)-10(-7) M) but not high doses of etomidate (10(-6)-10(-5) M). In cells from Cushing's syndrome the changes in corticosteroid secretion were similar to those found in primary aldosteronism except that aldosterone and 18-hydroxycorticosterone could not be determined due to their low levels. Thus the potent inhibition of corticosteroids in human pathologic adrenocortical cells in the presence of low concentrations of etomidate may be predominantly due to inhibition of the 11 beta-hydroxylase enzyme, whereas higher doses of the drug may inhibit earlier steps of the corticosteroid biosynthetic pathway.

Low concentration of Triton X-100 inhibits diacylglycerol acyltransferase without measurable effect on phosphatidate phosphohydrolase in the human primordial placenta

Agents causing accumulation of endogenous diacylglycerols (DAG) may be helpful in studies on the intracellular regulatory effects and on the mechanisms of attenuation of this putative second messenger. In a previous study (Tóth et al., BBA 921 (1987) 417-425) we have shown a marked stimulatory effect of low micellar concentration (0.05%, v/v) of Triton X-100 on the labelling of phosphatidic acid with (32P)phosphate in minced human primordial placenta. The present results demonstrate that 0.05% Triton X-100 inhibits nearly completely the conversion of (3H)diacylglycerols into (3H)triacylglycerols in placenta fragments incubated with (3H)glucose. However, this concentration of the detergent does not have any effect on the appearance of label in the sum of acylglycerols (comprising mono-, di- and triacylglycerols) and phosphatidylcholine, indicating a lack of effect on phosphatidate phosphohydrolase. The about 5-fold elevation of (3H)diacylglycerols was attended by an approximately 3-fold rise in (3H)phosphatidic acid and a 1.3-fold increase in the labelling of phosphatidylcholine. These findings provide supportive evidence that 1,2-DAG was formed due to inhibition of DAG-acyltransferase and suggest that some of the DAG was transformed into phosphatidic acid by diacylglycerol-kinase.

[Possibilities of antioxidant therapy in the prevention of side effects of amiodarone]

The authors demonstrated the generation of a very reactive phenyl radical from amiodarone in a reducing molecular environment by pulse radiolysis study. The various antioxidants are probably not capable of preventing the generation of phenyl radical, as well as to protect against its damaging effects on the neighboring molecules. Electron microscopic studies from lung tissue of in vivo treated rats showed that the simultaneous Silibinin (a flavonoid type antioxidant) treatment with amiodarone decreased significantly the lysosomal phospholipoidosis induced by amiodarone compared with the amiodarone treated group, but it didn't prevent entirely the accumulation of lysosomal phospholipids. The in vitro lysosomal beta-glucuronidase enzyme release measured from the liver tissue of in vivo treated rats increased significantly on amiodarone treatment, the antioxidants used (Silibinin, and the dihydroquinoline type MTDQ-DA) didn't exert any favorable effect. The authors discuss in details the possible relationships between free radical reactions and lysosomal phospholipoidosis.

Atrial natriuretic peptide (ANP) in patients with chronic renal failure on maintenance haemodialysis

Atrial natriuretic peptide (ANP), a recently discovered cardiac hormone, is an important regulator of body fluid homeostasis. Twenty patients with established chronic renal failure and on maintenance haemodialysis were studied before and after dialysis with capillary dialysers. ANP was determined by RIA after extraction. Mean (+/- SD) pre-dialysis ANP concentration was 146 +/- 51 pg/ml and decreased significantly during dialysis to 68 +/- 38 pg/ml (p less than 0.001). Per cent and absolute changes in plasma ANP level correlated significantly with concomitant changes in body weight (r = 0.764; p less than 0.001 and r = 0.558; p less than 0.01, resp.) but not with changes in serum creatinine, blood pressure or serum electrolytes. The obtained results indicate that ANP levels in patients with chronic renal failure are elevated mainly due to fluid overload, and the rapid fall in ANP concentration observed during haemodialysis is caused by the removal of excess fluid from the body.

Effects of carbachol and (-)-N6-phenylisopropyladenosine on myocardial inositol phosphate content and force of contraction

1. The effects of carbachol and the A1-adenosine receptor agonist (-)-N6-phenylisopropyladenosine (PIA) on force of contraction and inositol lipid metabolism were studied in electrically driven left auricles and papillary muscles isolated from guinea-pig hearts. Both carbachol and PIA (0.01-10 microM) had concentration-dependent negative inotropic effects in auricles. In papillary muscles PIA had no inotropic effect. Carbachol also had no inotropic effect at low concentrations (0.01-1 microM) but at 10-100 microM it exerted a slight positive inotropic effect. 2. In auricles and papillary muscles both carbachol and PIA concentration-dependently increased inositol trisphosphate (IP3; significant at 1 microM). Accordingly phosphatidylinositol bisphosphate (PIP2), the precursor of IP3, was reduced. All effects of carbachol and PIA were antagonized by atropine (10 microM) and 1,3-dipropyl-8-cyclopentylxanthine (DPCPX; 20 microM) respectively, indicating receptor-mediated effects. 3. In auricles the negative inotropic effects of carbachol and PIA preceded the increase in IP3. 4. In papillary muscles the increase in IP3 preceded the slight positive inotropic effect of carbachol, indicating that the M-cholinoceptor-mediated increase in IP3 and force of contraction may be related. However, PIA showed a comparable increase in IP3 but no inotropic effect, indicating a dissociation between those parameters. 5. In conclusion, in previous studies a close relation between increases in IP3 and force of contraction has been shown after alpha 1-adrenoceptor stimulation. The present study with carbachol supports this view. However, the present data for PIA could not show such a close relationship, questioning the role of IP3 as an endogenous regulator of force of contraction.

[The role of exchangeable sodium content of the body in cases of hypertension of various etiology]

Measurement of exchangeable sodium by isotope dilution is a relatively simple, reliable method for the determination of body sodium contents, which can be used in the clinical practice without significant health hazard to the patient. When computed to body surface area, the values for exchangeable sodium can be compared in patients of different body build. Exchangeable sodium may be variably increased in different clinical conditions associated with hypertension, thus increased sodium contents of the body is of major importance in the pathogenesis of hypertension caused by all forms of mineralocorticoid excess, and in the majority of patients with chronic renal insufficiency. In several endocrine disorders, e. g., acromegaly, hypothyroidism, increased sodium space does not play any significant part in the pathogenesis of hypertension. In diabetes mellitus, exchangeable sodium may be increased already prior to the development of hypertension, however it is still a matter of debate whether this abnormality is involved in the pathogenesis of hypertension in these patients. It seems now beyond any doubt that body sodium is normal in patients with essential hypertension, including those with the low renin form of the disease; nevertheless, some data indicate that blood pressure may be volume dependent in elderly patients with essential hypertension.

The possible role of tear fluid thyroxine in keratoconus development

The normal thyroxine level in tears was found to be two orders of magnitude lower than in serum. In thyroxine function tests, keratoconus patients were found to be hypothyreotic, euthyreotic or hyperthyreotic. However, independently of their thyroid function, the tear thyroxine levels of keratoconus patients were 2-50 times higher than that of subjects free of ocular pathology. Tear thyroxine levels were higher during the progression of keratoconus and declined once corneal curvature reached a new steady value.

[Malignant histiocytosis associated with chronic hepatitis]

A case of malignant histiocytosis successfully treated with splenectomy and chemotherapy is presented. 33 months after surgery the patient's overall condition is satisfactory. The result is attributed to the fact, that in the time of the operation there was no systemic proliferation. The concomitantly present chronic viral hepatitis was worsened by the treatment.

[The significance of Campylobacter pylori infection in gastroenterologic and diabetic practice]

The presence of Campylobacter pylori was investigated in gastric antral biopsy specimens. In 50 consecutive patients undergoing upper gastrointestinal tract endoscopy microbiological cultures, histological examination and rapid urease test were parallel performed, and a 92 per cent sensitivity and 100 per cent specificity of rapid and cheap urease test were determined. Afterwards--in a prospective study--311 patients were examined for C. p. by the rapid urease test only. C. p. was detected in 92 per cent of duodenal ulcer patients, in 52 per cent of patients with gastric ulcer, in 67 per cent of non-ulcer dyspepsia, in 62 per cent of mixed diabetic patient material, and in 21 per cent only of asymptomatic volunteers. It has been found by the authors, that the rate of C. p. infection increased parallel with the continuance of diabetes and did not follow the increasing with age as in the general population. This is the first observation in the world literature concerning the correlation between C. p. and diabetes mellitus. Very close, significant correlation has been found between C. p. infection and chronic active gastritis. C. p. may play an important role in the recurrences of duodenal ulcer and in the pathogenesis of non-ulcer and diabetic dyspepsia. Further studies are planned to the correct evaluation of pathogeneity of Campylobacter pylori.

[Regression of a pituitary tumor, associated with primary hyperthyroidism, under the effect of 1-thyroxine]

The authors report on a successful medical treatment of a 36-year-old woman who had hypothyroidism and pituitary adenoma. Primary hypothyroidism was evidenced by decreased serum thyroxine (23 nmol/l; 1,77 micrograms/dl) and increased plasma thyroid-stimulating hormone (TSH) levels (108 mU/l). Pituitary mass with suprasellar expansion (1 cm in diameter) was proven by computed tomography (CT). The patient had been treated conventionally with 1-thyroxine and this medication was continued during a 1-year follow-up. Not only did she become symptom-free but control CT scanning revealed a large reduction of tumor size and the disappearance of suprasellar expansion.

The relation between thromboxane and prostaglandin synthesis in human decidua tissue: a comparison of eicosanoid synthesis in minced tissue with that in a cell-free preparation

Radiotracer studies and radioimmunoassay measurements demonstrate that minced tissues of human decidua produce chiefly thromboxane B2 (TxB2) (70% of total eicosanoids) and small amounts of prostaglandin F2 alpha (PGF2 alpha) (13%) PGD2 (8%), 6-keto-PGF1 alpha (5%) and PGE2 (4%). Inhibition of thromboxane synthesis with a specific inhibitor (OKY-1581: sodium (E)-3-[4(-3-pyridylmethyl)-phenyl]-2-methyl propenoate) increased prostaglandin formation in general, with the main product being PGF2 alpha (38%), a nonenzymic derivative of PGH2. Crude particulate fractions prepared from the same tissue synthesized two major products from [3H]arachidonate, TxB2 and 6-keto-PGF1 alpha (54 and 30%, respectively) and some PGF2 alpha and PGE2 (8-8%). However, in the presence of reduced glutathione (GSH), PGE2 became the main product (81%) (TxB2, 15%; PGF2 alpha, 2%; and 6-keto-PGF1 alpha, 2%). Half-maximal stimulation of PGE2 synthesis occurred at 46 microM GSH. The GSH concentration of tissue samples was found to be 110 +/- 30 microM. We conclude that human first trimester decidua cells possess the key enzymes of prostaglandin and thromboxane synthesis. Apparently, the production of these compounds is controlled by a specific mechanism in the tissue, which keeps PGE and prostacyclin synthesis in a reversibly suppressed state, whereas the formation of thromboxane is relatively stimulated.

Evidence for alpha 1-adrenoceptor-mediated increase of inositol trisphosphate in the human heart

In human-isolated ventricular myocardium the alpha 1-adrenoceptor agonist phenylephrine has a positive inotropic effect but its mechanism is largely unknown. We studied the effects of phenylephrine in trabeculae isolated from three nonfailing human hearts. We found that the force of contraction rose concentration-dependently (1-300 mumol/L), maximally, to about 235% of control (at 100 mumol/L). The inositol phosphates were increased to 195-262%, whereas the phosphatidylinositol phosphate and phosphatidylinositol bisphosphate decreased to 69-73% of control. The present results suggest that the alpha 1-adrenoceptor-mediated increase in inositol trisphosphate and the positive inotropic effect may be causally related in the normal human heart.

Differential effect of progesterone on the labeling of phosphatidylinositol with [3H]inositol and [32P]phosphate in the uterus of the estrogen-treated ovariectomized rat

In rat uterine mince incubated in vitro [3H]inositol was found to be incorporated into phosphatidylinositol (PI) predominantly via a pathway which could be markedly and dose dependently activated with Mn2+ (0.1-10 mM) and inhibited by Ca2+ (1-10 mM). These ions had no effect on the incorporation of [32P]phosphate (32P) into PI indicating a distinct inositol-exchange mechanism for the labeling of PI with [3H]inositol. Treatment of ovariectomized rats for 5 days with 2 micrograms estradiol dipropionate (EDP) increased about 3-fold (when measured in the presence of 1 mM Mn2+) and 4-5-fold (when measured in the presence of 1 mM Ca2+) the inositol-exchange activity in the rat uterus, and these effects were suppressed by 40 and 30% respectively by the concomitant administration of 2 mg progesterone (P). EDP alone or in combination with P increased to the same extent (by a factor of 2-3) the rate of labeling with 32P of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and plasmenylethanolamine (PmE). The labeling rate of PI was increased 1.5-1.7-fold by treatment with EDP and this increase was selectively augmented further to about 2.5-fold by the simultaneous administration of P. Treatment with P alone had no significant effect on the incorporation of either labeled precursor. Steroid hormone treatments had no effect on the amount of these phospholipids in 100 mg uterine tissue, but they increased about 1.7-fold the rate of labeling of ATP with 32P. We conclude that P, when administered together with estradiol, regulates differentially the turnover of the inositol and phosphate moieties of PI with possible physiological consequences.

Triton X-100 promotes the accumulation of phosphatidic acid and inhibits the synthesis of phosphatidylcholine in human decidua and chorion frondosum tissues in vitro

Triton X-100 is known to affect phospholipid metabolism and the generation of various signal molecules from cellular phospholipids. In the present work the effect of Triton X-100 on phospholipid metabolism of human decidua and of the primordial placenta (chorion frondosum) was studied. Triton X-100 (0.05%, v/v) added to tissue mince 30 min before the end of a 60 min incubation stimulated 2-4-fold (decidua) and 4-6-fold (placenta) the incorporation of [32P]phosphate ([32P]Pi) into phosphatidic acid, while markedly decreasing the labeling of phosphatidylcholine. Triton X-100 had no effect on the labeling of phosphatidylinositol in the decidua, and only a slight increase was observed in the placenta. When labeled glucose was used to assess phospholipid synthesis, the addition of Triton had no effect on phosphatidic acid, while decreasing the synthesis of phosphatidylcholine. Incorporation of [32P]Pi into phosphatidic acid was not accelerated by a submicellar concentration (0.01%) of Triton, whereas the synthesis of phosphatidylcholine was decreased irrespective of detergent concentration. Anionic or cationic detergents could not mimic the action of Triton on phosphatidic acid synthesis. Although Triton inhibited the synthesis of ATP in a dose-dependent manner, this could not account for the above results. Instead, it is suggested that diacylglycerol kinase and phosphocholine:CTP cytidylyltransferase are possible targets of the action of Triton X-100.

Influence of dopamine on atrial natriuretic peptide level in premature infants

The role of dopamine (DA) in the activation and/or release of atrial natriuretic peptide (ANP) was investigated in 11 premature infants during the early postnatal period. Mean plasma concentration of ANP and free DA level before DA infusion was 252.6 +/- 210 fmol/ml, and 0.4 +/- 0.2 ng/ml, respectively. DA infusion in a dose of 2 micrograms/kg/min caused a rise in plasma free DA level to 59.7 +/- 21.5 ng/ml and a significant increase in GFR, diuresis, sodium excretion and fractional sodium excretion. The plasma concentration of ANP, however, remained unchanged (252.6 +/- 210.0 vs. 213 +/- 143.0 fmol/ml). Thus, our data failed to demonstrate a stimulatory effect of DA on ANP release in premature infants. The role of the high plasma concentration of ANP in preterm neonates immediately after birth has to be clarified.

Role of atrial natriuretic peptide in sodium homeostasis in premature infants

To examine the possible involvement of atrial natriuretic peptide (ANP) in sodium homeostasis in premature infants, two groups of low birth weight infants with different dietary sodium regimens were studied. Sodium balance and plasma concentration of ANP were measured at weekly intervals for 5 weeks. At 1 week of age the study was started by dividing infants into two groups, group 1 with low and group 2 with increased sodium intake. Mean plasma concentrations of ANP were 47.7 +/- 7.6 and 51.4 +/- 9.5 fmol/ml, respectively. A steady decrease in plasma ANP concentration to 18.8 +/- 2.9 fmol/ml was observed in infants with sodium intake 1.5 mmol/kg/d (group 1), which was related to the decrease in serum sodium concentration in this group. In contrast, supplementation with NaCl 4.6 mmol/kg/d (group 2) was associated with a 30% increase in plasma ANP concentration, significantly different (P less than 0.025) from that in infants not given supplement, and was also higher than the values in full-term neonates. Our data suggest that altered sodium homeostasis induces regulatory changes in plasma ANP levels. ANP may provide a sensitive and important hormonal system for the control of sodium balance, even in premature neonates.

Assignment of anabolic-androgenic and antiandrogenic properties to some chlorine-substituted steroids on the basis of their binding characteristics to the androgen receptor of the rat seminal vesicle

In this study we investigated the affinity of several 4-chlorinated and 1-ene derivatives of 17 alpha-methyltestosterone (MT) and 17 alpha-methyl-5 alpha-dihydrotestosterone (MDHT) to the androgen receptor, and, additionally, the effect of a few MT-derived steroids on the activity of the 5 alpha-reductase enzyme present in the rat seminal vesicle. From our results we conclude, that delta 1 or/and delta 4 double bonds in ring A counteract the inhibition of receptor-binding caused by chlorine-substitution at C4; the dissociation of myotropic and androgenic effects [= M/A dissociation] of 4-chloro-MT (as compared to MT) is due to its inactivation by 5 alpha-reductase in androgen target organs and/or to the inhibition of the conversion of endogenous testosterone to DHT; the M/A dissociation of 1-ene-MT and 4-chloro-1-ene-MT may be explained by their inability to be activated by 5 alpha-reductase; for the same reason, M/A dissociation can be assigned to the effects of 4 alpha-chloro-1-ene-DHT. We determined the short-term and long-term competition of cyproterone acetate and chlormadinone acetate with [3H]DHT for receptor binding at 0 degrees C and showed, that the complexes formed by these antiandrogens with the androgen receptor have equally reduced stabilities compared to the DHT-receptor complex.

Classification of anabolic steroids using the method of competitive metabolism

The effect of increasing concentrations of testosterone (T) and 19-nortestosterone (N) on the in vitro metabolism of [3H]N in minced tissue of the rat seminal vesicle indicates that T and N are equally appropriate substrates for the 5 alpha-reductase. Experiments in which increasing concentrations of 17-methyl-T (MT) or 1-ene-MT were incubated with [3H]T and vesicular mince have revealed that the formation of [3H]5 alpha-dihydro-T is suppressed markedly by MT while 1-ene-MT has no measurable effect. Since 5 alpha-dihydro-MT binds to the androgen receptor with a higher affinity than MT does and (relative to T) MT does not exhibit myotropic-androgenic (= M-A) dissociation, it can be concluded that MT is, whereas 1-ene-MT is not a substrate for the 5 alpha-reductase. Our present and previous data suggest that N exemplifies one class of anabolic steroids that become less androgenic due to 5 alpha-reduction, it shows high myotropic activity, M-A dissociation (= 7-30) and affinity to the androgen receptor. On the other hand, 1-ene-MT belongs to another class of anabolic steroids that are not substrates for the 5 alpha-reductase, exhibit a relatively small myotropic activity, M-A dissociation (= 2-3) and receptor affinity.

Effect of estradiol and progesterone on the rate of incorporation of radiolabeled arachidonate into phospholipids and triglycerides of the rat uterus

To obtain information on the effect of estradiol (E) and progesterone (P) on the overall rate of the acylation and deacylation reactions with [3H]arachidonate ([3H]AA) in the rat uterus, we investigated the effect of chronic treatment of ovariectomized rats with 2-200 micrograms/day E-dipropionate (EPP) and with 2 mg P alone or with the combination of these steroids on the extent and the time course of the in vitro incorporation of [3H]AA into various phospholipids (PLs) and the triacylglycerol fraction (TG). The results demonstrate that physiologic doses of E leads to a rapid equilibrium of the deacylation-acylation cycle only in the case of phosphatidylinositol (PI) whereas at high (200 micrograms/day) dose level it exerts the same effect on phosphatidylcholine (PC), phosphatidylethanolamine (PE) as well as on TG. P alone has no remarkable effects in the ovariectomized rat, but it decreases markedly the incorporation of [3H]AA into PI and TG in intact animals. Furthermore, P decreases the incorporation of [3H]AA into PI in the ovariectomized rat treated with 2 micrograms/day EPP as well as attenuating the enhanced labeling of PC, PE and PI caused by higher doses. Time-course studies provide evidence that all of these effects of progesterone can be accounted for by its ability to decrease the rate of deacylation and, therefore, to prolong the time needed to attain equilibrium in the rates of acylation and deacylation reactions of the various lipids with arachidonate. These data offer a novel outlook on the regulatory role of progesterone and estrogens in uterine function.

Plant small nuclear RNAs. Nucleolar U3 snRNA is present in plants: partial characterization

Nuclei, isolated from a number of plant species by either of two independent, newly developed methods, regularly contained a common set of low-molecular-mass RNAs. Partial characterization of these RNAs, based on cell fractionation, polyacrylamide gel electrophoretic and chemical sequencing techniques, as well as comparison with literature data, revealed that, in addition to tRNA, 5S RNA and 5.8S RNA, plant nuclei contain two families of low-molecular-mass RNAs, that are counterparts of vertebrate U1 and U5 RNAs respectively, and three individual low-molecular-mass RNA species. One of these may be related to vertebrate U6 RNA. The two others are true eukaryotic U2 and U3 RNAs, respectively, on the basis of the following lines of evidence obtained from analyses of broad bean nuclear RNAs. The 3'-end portion (121 nucleotides sequenced) of broad bean U2 RNA shows a nearly perfect sequence homology with that of authentic pea U2 RNA. Broad bean U3 RNA is localized in the nucleolus and its 3'-end portion (164 nucleotides sequenced) (a) shows sequence homology with that of both rat U3 RNA (48%) and Dictyostelium D2 RNA (39%), (b) has a secondary structure which fits perfectly that proposed for both rat U3 RNA and Dictyostelium D2 RNA, and (c) contains the specific sequence which, in a model based on the primary structure of rat U3 RNA, is supposed to be involved in the processing of eukaryotic 32S pre-ribosomal RNA. This is the first report on the occurrence in plants of nucleolar U3 RNA.

Prenatal diagnosis of cystic fibrosis by trehalase enzyme assay in amniotic fluid

Amniocentesis and amniotic fluid trehalase enzyme assay were offered to 14 pregnant women at a 1 in 4 risk for a child with cystic fibrosis. Twelve of these pregnancies were screened at the 18th week of gestation; ten proceeded to term, seven following the finding of a normal trehalase activity and three despite the low enzyme level in amniotic fluid. In all ten cases prenatal diagnosis proved to be correct. In two cases with low enzyme activity parents opted for termination at the 19th week, and with PAS-Alcian Blue staining some slight histochemical lesions characteristic of cystic fibrosis were seen in the exocrine glands, including the pancreas and intestinal mucosa, of both fetuses. The total protein content in the meconium of these fetuses was significantly higher than in the controls. Results suggest that trehalase assay in the amniotic fluid is a potential prenatal test for cystic fibrosis and it appears that in fetuses with cystic fibrosis some histochemical and biochemical abnormalities can be observed as early as the 19th week of gestation. The role of ultrasound examination as an additional procedure for the prenatal diagnosis of cystic fibrosis is also discussed.

Human interferons alpha and beta have more potent priming activities than interferon gamma

The priming activities of human IFN-alpha, IFN-beta and IFN-gamma were compared on the same antiviral basis using human buffy coat leukocytes stimulated with Sendai virus or concanavalin A (Con A) to produce IFN-alpha or IFN-gamma, respectively. Pretreatment of leukocytes with any type of IFN enhanced their IFN-alpha and IFN-gamma production, but IFN-alpha and IFN-beta had more potent priming activities than IFN-gamma. IFN-alpha and IFN-gamma did not potentiate the priming activity of each other in either the IFN-alpha or the IFN-gamma producing system. Pretreatment of leukocytes with relatively high doses of IFN-alpha or IFN-beta (1000 to 3000 IU/ml) resulted in a 40- to 50-fold increase in the IFN-gamma production of Con A-stimulated leukocytes. This observation will be of use in producing IFN-gamma with a high titre.

PGE2 binding, synthesis, and distribution in hen oviduct

Prostaglandin E2 (PGE2) bound specifically to particulate fractions prepared from the vagina and uterus (shell gland) portions of the hen oviduct in a time and temperature dependent fashion. Scatchard analysis indicated a single class of high-affinity binding sites in the vagina (Kd congruent to 1 nM), whereas the myometrium exhibited two kinds of binding site populations (Kd1 congruent to 1 nM, Kd2 congruent to 20 nM). It is suggested that these binding sites represent specific PGE2 receptors mediating the effects of PGE2 in oviductal smooth muscle. Vaginal particulate fractions produced approximately four times more prostanoids from [3H]-arachidonate than did uterine preparations. In the presence of epinephrine both tissues synthesized mainly thromboxane (TxB2), PGE2, and significantly less prostaglandin F2 alpha (PGF2 alpha). Addition of glutathione (GSH) or cytosol prepared from the oviduct markedly increased the yield of PGE2 at the expense of TxB2. Of the five morphologically discrete regions of the oviduct the vagina, infundibulum, and uterus contained the highest amounts of PGE and PGF, whereas the magnum and isthmus portions contain the least. TxB2 and 6-keto PGF1 alpha could not be detected in significant quantities in either region. These studies support the notion that PGE2 play a key role in the physiology of oviposition.

[Molecular aspects of interferon induction by adenoviruses]

The capacity of adenovirus to induce interferon in the infected cells was studied. The examined adenovirus strains of early types were grouped in 2 groups according to their capacity to induce interferon and to the sensitivity of the infecting and interferon-inducing activity to UV-irradiation. A common property of adenoviruses, potent interferon inducers, is their high sensitivity to UV-irradiation.

The left part of the viral genome is sufficient for interferon induction by adenovirus type 12

Adenovirus type 12 is a potent interferon inducer on chick embryo cells. Incomplete particles induce similar levels of interferon as complete virions, even if they contain only the left 20 per cent of the genome. Empty capsids lacking DNA are not able to induce interferon, suggesting that part of the viral genome is required to trigger the cells to produce interferon.