[Cardiovascular effects of calcium antagonists]

In this brief review, the most relevant points of the history of calcium-antagonists are described including their use in Chinese medicine. The mechanism of action on the heart and peripheral vessels is also reported. Finally, the therapeutic use of calcium antagonists in arterial hypertension is discussed.

[Pharmacokinetics and nephrotoxicity of aminoglycoside antibiotics]

Aminoglycoside antibiotics are characterized by a quick fall of blood levels (half-life 2-3 hours) and by a very slow urinary excretion (they can be detected in the urine up to 10-20 days after therapy is discontinued). This peculiar pharmacokinetic feature of these antibiotics may be attributed to some rapid steps of their pharmacokinetics (glomerular filtration, tubular reabsorption or uptake, storage in the renal cells) followed by a very slow step (transfer from these cells to tubular lumen with following urinary excretion). The aminoglycosides are very polar compounds and their uptake by tubular cells is mediated by an active transport. The uptake is responsible for the storage in the corticorenal cells. It is generally held that the storage, because of its long duration, is responsible for the nephrotoxicity, although the correlation between storage and nephrotoxicity is denied by some authors. Some practical implications of aminoglycoside pharmacokinetics could be: a) Kidney damage by aminoglycosides is often reversible, but the potential risk of nephrotoxicity must be considered to be still present at the time of the interruption of therapy. Therefore the measures during aminoglycoside therapy (prophylaxis of risk factors, monitoring of renal function, etc.) are to be continued also in the period immediately after the interruption of therapy. b) In animals some factors (high-calcium diet, calcium blockers, ACE inhibitors) are able to reduce aminoglycoside nephrotoxicity; some of them are operating through inhibition of uptake. It would be desirable to test the possible ability of these factors to reduce aminoglycoside nephrotoxicity in humans.

[On the eventual psychotropic, cardiovascular and aphrodisiac properties of yohimbine, an old drug with new indications]

The authors examined pharmacological actions of Yohimbine, an indolic alkaloid alpha-2-adrenoceptor antagonist. Several specific functions have been attributed to the alpha-2-adrenoceptor such as reduction of sympathetic outflow and pre-synaptic inhibition of noradrenergic neurons. Particularly the following are discussed: behavioural, antidepressant and anxiogenic effects: aphrodisiac effect; cardiovascular effects and metabolic effects.

Evidence for the presence of specific binding sites for corticoids in mouse liver plasma membranes

The specific binding of [3H]cortisol to plasma membranes purified from mouse liver, studied by the ultrafiltration method, shows the existence of specific binding sites for cortisol. The kinetic parameters of this binding are KD = 4.4 nM and Bmax = 685 fmol/mg protein in presence of 1 microM of corticosterone. With respect to the binding of 4 nM [3H]cortisol to the membrane, the affinities of the steroids decreased in the following order: deoxycorticosterone greater than corticosterone greater than progesterone greater than cortisol greater than prednisolone greater than testosterone greater than 20 beta-hydroxyprogesterone greater than cortisone. Estradiol, dexamethasone, ouabain and triamcinolone acetonide do not have affinity for this binding site. Neither Ca2+ nor Mg2+ affected the binding of [3H]cortisol to the plasma membranes. Likewise, the presence of agonists and antagonists of alpha and beta-adrenergic receptors did not modify the binding of [3H]cortisol. The results suggest that the plasma membrane binding site characterized is more specific for corticoids and is different from nuclear glucocorticoid and progesterone receptors.

[Measurement of benzene in the urban area of Naples]

The aim of this study is to determine the occurrence of benzene in the air of the city of Naples. A simplified gas-chromatographic method that is sensitive and provides accurate measurements of ambient concentration of benzene has been used. In the centre of Naples the concentration of hydrocarbons depends strongly upon vehicle exhaust.

[Drugs used in the therapy of peptic ulcer with special reference to H2 receptor blockaders]

Drugs used in the management of peptic ulcer are reviewed with special attention to the possibilities offered by H2 receptor antagonists. In this context, histaminergic transmission and distribution of H2 receptors are briefly reviewed. Among other substances, special interest has been raised by H+ and K+-dependent ATPase inhibitors; the most recently introduced derivatives of these substances which are as yet in the experimental stage, are also listed.

[Sterols from Gynostemma pentafillum]

The sterol fraction of Gynostemma pentafillum contains beta-sito sterol and isofucosterol. The identification of these compounds has been carried out through NMR and MS data.

Characterization of specific binding sites for corticosterone in mouse liver plasma membrane

The specific binding of [3H]corticosterone to mouse liver purified plasma membrane fractions is a saturable, reversible, and temperature-dependent process. Only one type of independent and equivalent binding sites has been determined in plasma membrane (Kd = 4.1 nM and Bmax = 3368 fmol/mg). As can be deduced from displacement data obtained in plasma membrane, the high-affinity binding site is different from nuclear glucocorticoid, nuclear progesterone, and Na+, K(+)-ATPase digitalis receptors. Probably this corticosterone binding site or receptor is the same one determined previously for [3H]cortisol in mouse liver plasma membrane. Such beta- and alpha-adrenergic antagonists as propranolol and phentolamine did not affect [3H]corticosterone binding to plasma membranes; therefore, this binding site is independent of these receptors. The binding sites in plasma membranes are not exclusive for corticosterone, but other steroids are also bound with very different affinities.

Mexiletine for the treatment of ventricular arrhythmias associated with chronic obstructive pulmonary disease

Ventricular arrhythmias complicating chronic obstructive pulmonary disease, when refractory to the correction of acidosis and hypoxia, may lead to a poor prognosis. Mexiletine efficacy was assessed in 14 patients (pts.) with chronic obstructive pulmonary disease and premature ventricular contractions; they entered a cross-over trial consisting of 7-day therapy with oral placebo and mexiletine (200 mg q.i.d.). The hourly means of premature ventricular contractions, their hourly peaks and the severity scores of arrhythmias were compared. The analysis of linear regression showed a slight spontaneous variability of premature ventricular contractions in the study group. Unexpectedly, the highly homogeneous data raised the question if this method of evaluation for anti-arrhythmic therapy reaches a satisfactory conclusion. Nevertheless, treatment with mexiletine significantly reduced the premature ventricular contractions count and their hourly peak (p less than 0.001) as well as their severity score (p less than 0.001). Analysis of linear regression and confidence intervals confirmed the efficacy of the drug. According to the statistical method used, antiarrhythmic therapy with mexiletine generally achieved its purpose in pts. with chronic obstructive pulmonary disease.

Glycogen phosphorylase activation by progesterone in liver

Glycogen phosphorylase activity is increased before protein synthesis activation by progesterone. This effect is not blocked by antibiotics (actinomycin D and cycloheximide) that are known to inhibit mRNA or protein synthesis. At times similar to those of phosphorylase activation, cAMP are not enhanced, as would be expected considering the classical glycogenolytic cascade, but depleted with respect to control values. A little earlier, cGMP levels are significantly increased.

Functional characterization of muscarinic receptors in rat parotid acini

The muscarinic agonist, carbamylcholine, stimulated amylase secretion in rat parotid acini 6-fold, the 86Rb efflux 5-fold, the 45Ca efflux 5-fold and the accumulation of inositol monophosphate, bisphosphate, trisphosphate and tetrakisphosphate 4-, 4-, 3- and 3-fold, respectively. The EC50 of carbamylcholine on these parameters were 0.4, 0.5, 1.3, 12, 12, 6 and 9 microM, suggesting spareness between phospholipase C activation and amylase secretion. These muscarinic responses were inhibited by four muscarinic antagonists with an order of potency on all parameters and on receptor occupancy (using N-[methyl-3H]scopolamine as a tracer): atropine greater than hexahydrosiladifenidol greater than pirenzepine greater than AF-DX 116. The pA2 of these antagonists on carbamylcholine-stimulated amylase secretion were 9.72 for atropine, 8.14 for hexahydrosiladifenidol, 7.16 for pirenzepine and 6.22 for AF-DX 116, indicating that the parotid muscarinic receptors were of an M2 subtype 83-fold more sensitive to hexahydrosiladifenidol than to AF-DX 116.

Somatostatin and SMS 201-995 reverse the impairment of cognitive functions induced by cysteamine depletion of brain somatostatin

The involvement of somatostatin in the organization of cognitive functions was studied. We assessed changes in learning and memory processes by studying the effects of cysteamine, a compound that decreases somatostatin-like immunoreactivity in the brain, somatostatin and the potent somatostatin analogue, SMS 201-995, on active avoidance behaviour, assessed with a shuttle box apparatus, or on passive avoidance behaviour. Cysteamine induced a loss of the conditioned active avoidance response acquired after 3 weeks of daily trials. The effect was observed 2 h (-29%) and 4 h (-51%) after cysteamine treatment (300 mg/kg s.c.) and disappeared after 24 h. Intracerebroventricular administration of somatostatin or SMS 201-995 to cysteamine-treated rats significantly reversed the cysteamine effects on the conditioned avoidance responses. Similar results were obtained on passive avoidance behaviour. We also investigated the effect of cysteamine treatment on brain somatostatin-sensitive adenylate cyclase. We observed that adenylate cyclase activity in the frontal cortex of cysteamine-pretreated animals was more sensitive to inhibition by the SRIF analogue, SMS 201-995, than it was in control animals. This effect was observed at concentrations of SMS 201-995 that were ineffective in control tissue. These results show that disruption of somatostatinergic transmission affects cognitive functions of rats.

[Enalapril and acebutolol in essential arterial hypertension. Comparison of the 2 drugs and evaluation of their combination]

The effects of a mid-term antihypertensive treatment with Acebutolol (A) 400 mg once-daily alone, Enalapril (E) 20 mg once-daily alone and their combination (A + E) in 12 hypertensive patients (pts.) have been evaluated. The diastolic (DBP) and systolic (SBP) blood pressure values have been evaluated in supine and upright position and at the end of an exercise test. Basic values obtained after 3 weeks of treatment with placebo have been matched with values observed after 3 months of each treatment (A; A + E; E). In order to evaluate the effectiveness of the combination, pts. were divided into two groups: the first group was given A, than A + E and finally E; in the second group the order was reversed. Our findings showed a more significant reduction of DBP in supine and upright position and after exercise (p less than .05) and of SBP in supine and upright position (p less than .05) after treatment with E. The addition of A to E did not produce a further significant reduction in blood pressure values except after exercise (p less than .01).

Increased phospholipid methylation and glycogen phosphorylase activation after a single dose of dexamethasone in mouse liver

Two different effects on phospholipid methylation and glycogen phosphorylase a activation were accomplished by treating mice livers with dexamethasone. A biphasic effect on the glycogen phosphorylase a was determined in the homogenated liver of dexamethasone-treated animals: The enzymatic activity increased between 45 to 90 min and decreased about 3 h. Moreover, the increased activity of glycogen phosphorylase a was also found in adrenalectomized mice. Also, the incorporation of ethanolamine into PE1) and PC1) after 15 min of hormone-administration was 77% and 270%, respectively, over the control values. The increase in phospholipid methylation was maintained during the first hour. After 4 h the hormone-treated animals also showed significant differences compared to the controls. Finally, studies of total lipid phosphorus content in the liver fail to show any differences between control and hormone-treated mice.

Somatostatin inhibition of anterior pituitary adenylate cyclase activity: different sensitivity between male and female rats

Somatostatin (SRIF) is a potent inhibitor of growth hormone (GH) secretion. Although cyclic AMP (cAMP) has been suggested as intracellular mediator of SRIF action, a complete characterization of its effect and the different sensitivity between male and female animals, has not yet been carried out. In this study SRIF inhibited basal and GH-releasing factor (GRF) stimulated anterior pituitary adenylate cyclase activity with a greater effectiveness in male than in female glands. Similarly SRIF reduction of forskolin-stimulated anterior pituitary adenylate cyclase activity, was more pronounced in male than in female animals. By using pertussis toxin (PTX), which uncouples inhibitory receptors from adenylate cyclase catalytic subunit, SRIF inhibition of both basal and forskolin-stimulated adenylate cyclase activity was nearly abolished. These results show that anterior pituitary SRIF receptors are coupled in an inhibitory fashion with adenylate cyclase enzyme, and that male rat adenohypophyses are more responsive to SRIF inhibition.

High-performance liquid chromatographic determination of norfloxacin in human tissues and plasma with fluorescence detection

A high-performance liquid chromatographic method with fluorimetric detection is described for the quantitative determination of norfloxacin in renal and prostatic tissues and in plasma. It consists of tissue pretreatment, purification by solid-state extraction and separation and quantification by high-performance liquid chromatography on a C8 reversed-phase column. Analytical recoveries ranged from 95.2 to 97.6%. Within-day and between-day precision were assessed by analysing serum containing 50 and 500 ng/ml norfloxacin. At each concentration, the within-day precision was less than or equal to 3.6% (coefficient of variation; n = 10) and the day-to-day precision was less than or equal to 5.3% (n = 10). The limit of detection was 1 ng/ml.

Characterization of cortisol binding sites in chicken liver plasma membrane

1. The presence of sites specifically binding [3H]cortisol in plasma membrane isolated from chicken liver has been determined. The kinetic parameters of this binding are: Kd = 4.5 nM and Bmax = 2225 fmol/mg protein in presence of 10(-6) M progesterone. 2. The affinities of several natural and synthetic steroids for the membrane binding site respect to the binding of 4 nM [3H]cortisol without competitor increased in the following order: Testosterone less than pregnenone less than dexamethasone less than progesterone less than prednisolone less than corticosterone less than deoxycorticosterone. 3. Other steroids such as estradiol, ouabain and triamcinolone acetonide does not bind to the plasma membrane. 4. Metal ions such as Ca2+ and Mg2+ did not modify the binding of [3H]cortisol. 5. Neither propranolol nor phentolamine, beta- and alpha-adrenergic antagonists affected [3H]cortisol binding to the plasma membranes. 6. The result suggest that the binding site detected is more specific for glucocorticoids and it is different of nuclear glucocorticoid receptor and progesterone receptor.

Two independent effects of cortisol on chicken liver

Activities of two key enzymes of glycogen metabolism have been measured after an acute administration of cortisol to 3d-old chickens. Glycogen synthase activity is enhanced 2-3 hours after a cortisol injection, and this activation is blocked by use of protein synthesis inhibitors. Glycogen phosphorylase activity is enhanced at an early stage, and this effect is not suppressed by protein synthesis inhibitors. Liver cAMP levels are not increased concomitantly with this early activation of glycogen phosphorylase; indeed they are depleted. These results point to the existence of an effect of cortisol previous to and independent of its nuclear interaction, and not mediated by an activation of the membrane adenylate cyclase.

Glycogenolytic effect of cortisol previous to its interaction with the cell nucleus in mouse liver

Activities of hepatic glycogen synthase a and glycogen phosphorylase a have been studied in mouse liver at different times after an acute intraperitoneal administration of hydrocortisone. It has been observed an increase of glycogen synthase a activity and a decrease of glycogen phosphorylase a between 2 and 3.5 hours after cortisol injection. An early effect, previous to the synthase activation has been discovered. Cortisol caused an increase of glycogen phosphorylase a activity in mice 45 min after injection. This early effect of cortisol is independent of protein synthesis and it does not imply an increase in cAMP levels.

HPLC determination of benzydamine and its metabolite N-oxide in plasma following oral administration or topical application in man, using fluorimetric detection

A method for the extraction and quantification of benzydamine and its metabolite N-oxide by liquid chromatography with fluorescence detection in plasma samples is described. This method has adequate sensitivity, specificity and is reproducible. The use of the extraction column allowed a recovery of both benzydamine and its metabolite of over 97% to be obtained. The plasma levels of benzydamine and its metabolite N-oxide were studied after oral administration as sugar-coated tablets or topical application to the vaginal mucosa as a cream to 6 healthy volunteers. After topical application, the plasma concentrations of the unchanged drug and its metabolite are lower than those obtained following oral administration. These data further stress the concept that, whenever possible, topical use should be considered the treatment of choice since, along with a more selective therapy, the incidence of systemic side effects can be considerably reduced.

Liquid-chromatographic determination of progesterone in serum, with spectrophotometric detection

In this precise, accurate, and specific liquid-chromatographic procedure for determining progesterone in serum, the serum is diluted 10-fold with water/methanol (65/35 by vol), and the progesterone is extracted from the sample by passage through a column of graphitized carbon black (Carbopack B, Supelco). After washing the column, we elute the progesterone with chloroform/methanol (90/10 by vol), which is then evaporated. The progesterone is separated on a reversed-phase C18 column with a mobile phase of acetonitrile/water, (46/54 by vol) at a flow rate of 1.6 mL/min. The eluted compound is detected by absorbance at 242 nm. Analytical recoveries for progesterone varied from 96.0 to 97.8%. Within-day and day-to-day precision, determined by analyzing pooled serum, ranged from 3.4 to 6.4%, and 4.1 to 7.9%, respectively. The limit of detection was about 0.2 micrograms/L. Numerous drugs and steroids tested did not interfere. Results correlated (r = 0.997) well with those by radioimmunoassay.

Liquid-chromatographic determination of progesterone in serum, with spectrophotometric detection

In this precise, accurate, and specific liquid-chromatographic procedure for determining progesterone in serum, the serum is diluted 10-fold with water/methanol (65/35 by vol), and the progesterone is extracted from the sample by passage through a column of graphitized carbon black (Carbopack B, Supelco). After washing the column, we elute the progesterone with chloroform/methanol (90/10 by vol), which is then evaporated. The progesterone is separated on a reversed-phase C18 column with a mobile phase of acetonitrile/water, (46/54 by vol) at a flow rate of 1.6 mL/min. The eluted compound is detected by absorbance at 242 nm. Analytical recoveries for progesterone varied from 96.0 to 97.8%. Within-day and day-to-day precision, determined by analyzing pooled serum, ranged from 3.4 to 6.4%, and 4.1 to 7.9%, respectively. The limit of detection was about 0.2 micrograms/L. Numerous drugs and steroids tested did not interfere. Results correlated (r = 0.997) well with those by radioimmunoassay.

Phosphatidylethanolamine methyltransferase activity in chick liver microsomes

The synthesis of phosphatidylcholine from phosphatidylethanolamine is carried out by chick liver microsomes (Gallus domesticus). Different concentrations of PE, NPE and NNPE were used as exogenous substrates. Saturation of the S-adenosylmethionine has been found for the three different reactions with or without exogenous substrate. Kinetic parameters have been determined for this enzyme system in chick liver microsomes. The three methyl reactions had a similar pH profile with an optimum at pH = 8. Divalent ions such as Ca2+ or Mg2+ did not stimulate the enzyme activity. The results suggest that the synthesis of phosphatidylcholine from phosphatidylethanolamine by chick liver microsomes exhibits a kinetic pattern with different aspects than that described for other animal or human preparations.

[Sterols from Basidiomycetes]

Sterols of three Basidiomycetes were determined. The main sterol was ergosta-5,7,22-trien-3 beta-ol, accompanied by other closely related sterols. Cholesterol was found only in trace amounts.

Effect of a single dose of triiodothyronine on the uptake of (methyl-14C)choline into chick liver phospholipids

The effects of a single dose of 3,3'-5-triiodothyronine (T3) on the uptake of (methyl-14C) choline into liver phosphatidylcholine (PC) and lysophosphatidylcholine (LPC) were studied in chicks as a function of time up to 6 h after injection of the radioactive precursor. In all cases, chicks received the T3 dose intraperitoneally 5 h before injection of the labelled compound. T3 enhances the incorporation of 14C-choline into liver PC, showing a biphasic response; the main uptake occurs between 2 and 3 h after administering the precursor. A smaller but significant hormone-dependent increase in incorporation of the labelled compound is observed in the case of LPC. Lipid P associated to PC and LPC remains constant throughout the experiment, and does not vary with hormone treatment. It is suggested that T3-injection increases, either directly or through other metabolic processes, PC and LPC turnover in chick liver cells.

An interaction of testosterone with cell membranes

The existence of an early effect of testosterone, prior to the effects dependent upon interaction between the hormone-citosolic receptor complex and the cellular nucleus, has been explored in the present paper, in 3-day old chickens. Liver glycogen phosphorylase activity is increased before protein synthesis activation, and furthermore this effect is not blocked by antibiotics (actinomicin D and cycloheximide) inhibitor of protein synthesis. When liver phosphorylase is activated, cAMP levels are not enhanced, as would be expected, but deeply depleted. The hypothesis of a phosphorylase-kinase activation due to an increase in the intracellular Ca++ concentration is considered.

Cholesterol biosynthesis in chicken liver: effect of triiodothyronine

The effect of a single injection of L-triiodothyronine (T3) on the levels of liver cholesterol and liver 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) has been studied in chicken. A minimal dose of 8 micrograms/animal produces its maximal effects after 12 h. T3 enhances both HMGR activity and cholesterol levels in liver. Both effects are suppressed when protein synthesis inhibitors (actinomycin D or cycloheximide) are administered along with the hormone. Solubilized and membrane-bound HMGR activities are equally influenced by the hormone. The in vitro addition of T3 does not affect the HMGR activity. It is concluded that T3 increases cholesterol biosynthesis in chicken liver through the activation of de novo protein synthesis.

Effect of a single dose of T3 on the uptake of (2-14C)-ethanolamine into chicken liver phospholipids

The effect of a single dose of 3,3',5-triidothyronine (T3) on the (2-14C)-ethanolamine uptake into liver phosphatidylethanolamine (PE) and lysophosphatidylethanolamine (LPE) were determined in chicken over a period of 0.25 to 6 h after radioactive precursor injection. In all cases animals received the T3 dose intraperitoneally 5 h before the injection of the labeled compound. T3 enhances the incorporation of (2-14C)-ethanolamine into liver PE and LPE. The maximum uptake takes place at 0.25 h for LPE and 0.5 h for PE after the precursor administration. A great and significant hormone-dependent increase in the incorporation of labeled compound is observed in LPE. Lipid P associated to PE and LPE remains constant throughout the experiment, and does not vary with hormone treatment. It is suggested that T3-injection increases, either directly or through other metabolic processes, PE and LPE turnover in chicken liver cells.

[Blood levels of lead and delta-aminolevulinic dehydratase activity in a Spanish population. Effect of occupational exposure and social habits]

The effect of tobacco and alcohol on the delta-amino levulinic dehydratase (ALA-D) activity and lead level in blood is studied in a population of workers with or without exposure to lead due to their work. The lead level in the blood of workers without exposure is about 15.9 +/- 1.7 micrograms/100 ml and is unaltered by sex. The ALA-D level for men and women is 289.7 +/- 15 U/100 ml and 255.9 +/- 10 U/100 ml respectively, the difference being due mainly to the smaller hematocrit for women. Without lead exposure smoking moderately does not change the ALA-D or the lead level, whereas alcoholic drink consumption increases the lead level but does not affect the ALA-D activity. When both factors concur the ALA-D activity decreases, while the lead level increases. With lead exposure, however, neither the ALA-D activity nor the lead level undergoes any change, with of without smoking and drinking, since the values have been completely altered by the exposure. A close relationship between ALA-D activity and lead level in blood has been found in each case.

[Liver phospholipid metabolism in Gallus domesticus (author's transl)]

A method is described for the extraction and thin-layer chromatographic separation of phospholipids. Eight separate phospholipid fractions are easily distinguishable. Liver phospholipid metabolism in Gallus domesticus has been studied in newborn chicken (less than 24 h old). (1-14C) serine, 3-14C) serine, (2-14C) ethanolamine and (methyl-14C) choline were used as radioactive precursors. Serine is incorporated as lysophosphatidylserine, ethanolamine as phosphatidylethanolamine, and choline as L-alpha-glycerophosphorylcholine. The observed pathways for serine and ethanolamine incorporation and turnover are the same as those described for mammals; the main pathway for choline is the synthesis of phosphatidylcholine from lysophosphatidylcholine.

Aortico-left ventricular tunnel in infancy. Two surgical cases

Two infants with aortico-left ventricular tunnel and associated aortic valvular disease were operated upon. The first patient, age 28 months, had successful surgical closure of the anomalous communication. Four years postoperatively he is asymptomatic, but mild aortic regurgitation persists. The second infant, aged 3 months (the youngest reported surgical case), also had severe aortic stenosis (dysplastic valve) and mitral regurgitation. She died, twelve hours after the operation, from intractable left ventricular failure. On the basis of the previously reported cases (22), the clinical profile of the malformation is outlined with special reference to associated aortic valve lesions. Early operation is recommended because of the poor natural history of the condition.