The carbochromene derivative AD6 reduces the TxB2/6-keto-PGF1 alpha ratio in cerebral cortex during hypoxia and recovery and leukotriene synthesis in brain tissue, in the rat

Pretreatments of rats with the Carbochromene derivative AD6 (4 mg/kg i.p., 2 h before sacrifice) resulted in elevation of brain levels of 6-keto-PGF1 alpha in cerebral cortex under physiological conditions, had no effect on levels of TxB2 and 6-Keto-PGF1 alpha at 30 min of hypoxia (respiration of 5% O2 in N2) and prevented the accumulation of TxB2 occurring in brain at 5 min of recovery after hypoxia. In addition, the accumulation of LTC4 and B4 in brain slices incubated in the presence of the Ca++ ionophore A23187 and arachidonic acid, was reduced in samples obtained from pretreated rats. The drug, thus, had favourable effects on the 6-keto-PGF1 alpha/TxB2 ratio in normal conditions, as well as in conditions of altered oxygen supply. In addition it reduced the formation of compounds, the leukotrienes, which may exert pro-inflammatory activities on the cerebral microcirculation.

Reduced protection against hepatitis B virus following vaccination in patients with type 1 (insulin-dependent) diabetes

Twenty patients with well controlled Type 1 (insulin-dependent) diabetes of at least 10 years duration and 47 control subjects were vaccinated against the hepatitis B virus using the Hevac B vaccine. The vaccine was administered into the deltoid region on three occasions at intervals of 1 month. Thereafter a fourth dose was given to subjects still negative for antibody to hepatitis B surface antigen (HbsAb). The median rise of HbsAb titres was 230 mIU/ml in normal subjects and 50 mIU/ml in diabetic patients (p less than 0.001). Eight patients (40%) failed to reach HbsAb titres above 30 mIU/ml, the level considered to give optimal protection against the infection, whereas only one normal control subject failed to reach this level. Five patients (25%) showed no response despite a fourth dose of the vaccine. There was an increased frequency of HLA-DR7 in low responders and a decreased (less than 1.5) helper/suppressor lymphocyte ratio. Diabetic patients are thus less likely to mount a protective antibody response following vaccination against hepatitis. Since hepatitis B surface antigen is reported to be considerably more common in diabetic patients than control subjects, infection with hepatitis B virus may have a greater risk of chronicity in diabetes.

Changes in systemic and pulmonary vascular reactivity in hypertension following nifedipine and verapamil

Excessive vascular tone and overresponsiveness to adrenergic stimuli characterize the hemodynamics of the greater and the lesser circulation in hypertension. We tested whether calcium entry blockade with verapamil (11 cases) or nifedipine (11 cases) may improve the vascular regulation in high blood pressure. Mental arithmetic and cold were used as adrenergic activators. The former stimulus produced obvious elevation of epinephrine plasma concentration, increase of cardiac output (CO), slight systemic vasodilatation, pulmonary vasoconstriction, and rise of blood pressure in both circuits. After calcium antagonists, the epinephrine reaction to the arithmetic test was significantly attenuated, variations in CO and systemic blood pressure were unchanged, pulmonary vasoconstriction was abolished, and the pressure rise in the lesser circuit was halved. The cold pressor test increased norepinephrine plasma concentration (NE pc), systemic and pulmonary blood pressure, and vascular resistance and did not alter CO. The attained NE pc during cold was unvaried after verapamil and significantly enhanced after nifedipine; pressure and resistance responses of the two circuits were almost unchanged after the former, whereas systemic and pulmonary vascular resistance rises were importantly attenuated after the latter compound, resulting in much lower pressure reactivity. A modulation of the sympathoadrenal reaction, per se, can explain changes in the systemic and in the pulmonary vasomotion with calcium blockade during arithmetic. It would seem that after verapamil the sympathetic system was still activated during cold to such an extent as to maintain the same vasoconstrictor potency. NE pc suggests that the sympathetic discharge was not reduced by nifedipine.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of hypoxia and recovery on brain eicosanoids and carbohydrate metabolites in rat brain cortex

The effects of hypoxia (respiration of 5% O2 for 30 min) and recovery (respiration of air up to 30 min) on brain levels of carbohydrate metabolites, of free arachidonate (FAA) and of several eicosanoids (E) were studied in the rat. Animals were sacrificed before or after 30 min of hypoxia, and during recovery, by microwave radiation (MW). At the end of the hypoxic period, arterial pO2 was reduced to 28 mm Hg and glycemia was elevated. Brain lactate and glucose levels were also elevated, whereas glycogen was unchanged. Levels of free FAA and of E were practically unchanged. During recovery, arterial pO2 values were raised above prehypoxic levels at 5 min and returned to normal within 30 min. The elevated serum glucose declined at 5 min and values returned to normal at 30. Brain glucose was still elevated at 5 min and returned to normal, together with lactate, at 30 min. Brain FAA did not change during recovery, but levels of prostaglandin F2 alpha (PGF2 alpha), prostaglandin E2 (PGF2) and thromboxane B2 (TxB2) were raised, at 5 min, and those of 6-keto-PGF1 alpha were reduced with respect to pre-hypoxia. At the end of recovery, all E were lower than during hypoxia. The results indicate that changes of brain E occur only during recovery from hypoxia. At 5 min of recovery, at high arterial pO2 values, concentrations of all E were elevated, with the exception of 6-keto-PGF1 alpha which was reduced. At 30 min a marked reduction of E levels was observed, possibly resulting from increased clearance following elevation of cerebral blood flow.

Invasive candidiasis does not complicate short-term cimetidine treatment of duodenal ulcer

The purpose of this study was to record the frequency of invasive candidiasis of duodenal ulcer and to determine whether or not it is enhanced by cimetidine treatment. Our multicenter prospective trial involved 99 patients with endoscopically proven duodenal ulcer who were undergoing a 4- or 8-week cimetidine (800 mg/day) treatment program. At the endoscopic examination, performed before and after the 4- or 8-week treatment, three biopsy samples were taken from the ulcer edge or from the healed tissue. Ulcer infiltration by Candida was presumed by the presence of mycetes in stained tissue samples. Healing rate was 76% at 4 weeks and 89.9% at 8 weeks. Candida infiltration was not seen in any biopsy specimen. Short-term treatment with cimetidine does not promote invasion of mycetes into the duodenal ulcer lesion.

In situ hybridization of human immunodeficiency virus (HTLV-III) in cryostat sections of lymph nodes of lymphadenopathy syndrome patients

The presence of human immunodeficiency virus (HIV, or HTLV-III) genome sequence was investigated by means of in situ hybridization in cryostat sections of lymph nodes from lymphadenopathy syndrome (LAS) patients. The technique employed involved the modification of the DNA probe by chemical insertion of an antigenic sulfone group in cytosine moieties and the visualization of DNA by a double-antibody immunohistochemical reaction. The hybrid formation was revealed in five out of ten cases: in all positive samples, HIV was mainly observed in the cytoplasm of lymph node cells. The method of in situ hybridization described in the present paper is specific and has some advantages if compared with other techniques based on the use of DNA probes labelled with radioisotopes or biotin by nick translation.

Lipid and phospholipid fatty acid composition of plasma, red blood cells, and platelets and how they are affected by dietary lipids: a study of normal subjects from Italy, Finland, and the USA

A pilot study was conducted of males 40-45 years old from rural areas of three countries to study the long-term effects of dietary fats on the lipids of plasma, red blood cells (RBCs), and platelets. Differences were observed in cholesterol and phospholipid levels of plasma. Total phospholipids of RBCs and platelets were similar in all three countries. The pattern of individual phospholipids of RBCs in the Finnish and Italian samples differed from the American samples. In all plasma and RBC glycerolphospholipids, the monounsaturated fatty acids were highest in the Italian and the saturated fatty acids were highest in the Finnish samples; PUFAs were highest in the USA samples. Platelet glycerolphospholipids followed similar fatty acid patterns. We concluded that the fatty acid compositions of the glycerolphospholipids of plasma, RBCs, and platelets reflect the major dietary fatty acids.

The lesser circulation in patients with systemic hypertension

The elevated blood pressure and vascular resistance in patients with systemic hypertension are paralleled by a proportional rise in pressure and resistance in the lesser circulation. We evaluated the hypothesis that the increased systemic reaction to adrenergic stimulation is shared by the pulmonary vessels. For this purpose we investigated nine normotensive subjects and 24 patients with moderate primary hypertension during mental arithmetic and the cold pressor test. Both groups responded to both stimuli, with a pressure reaction that during arithmetic was mediated through an increase of cardiac output, and a reaction during the cold pressor test mediated through a predominant rise in systemic vascular resistance. The pressure changes were emphasized in the hypertensive population. Pressure in the pulmonary artery in normotensive subjects was not affected by cold and was slightly raised (systolic) during arithmetic. In hypertensive patients, on the other hand, systolic and diastolic pressures were consistently augmented by both tests, and pulmonary arteriolar resistance rose by 42% and 29% of control during the cold pressor test and arithmetic, respectively. Changes in resistance reflected neurally mediated vasoconstriction and not variations in the passive relationship between pressure and flow, since during arithmetic, for a similar rise in flow the driving pressure across the lungs was steady in normotensive subjects and rose significantly in hypertensive patients. In these same patients pressure was augmented by cold in the absence of substantial changes in flow. At baseline and during tests pulmonary wedge pressure, pleural pressure, arterial blood gases, and pH were similar in the two populations.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary vascular supersensitivity to catecholamines in systemic high blood pressure

Pulmonary pressure and arteriolar resistance are elevated in uncomplicated primary systemic hypertension. This study was carried out in 16 men with this form of hypertension and in 9 healthy men to compare 1) their pulmonary vascular reactivity to endogenous catecholamines released during mental arithmetic and cold pressor tests, and 2) the dose-response relation to exogenous epinephrine and norepinephrine. Arithmetic and cold pressor tests were associated, respectively, with a predominant increase in plasma epinephrine and norepinephrine concentration; changes were significantly greater in hypertensive men. During the two tests, pulmonary arteriolar resistance in the normotensive group was reduced by 13% and augmented by 7% of baseline, respectively, whereas it was raised by 31 and 70%, respectively, in the hypertensive group. In normal subjects, the dose (microgram)-response (delta dynes) relation to epinephrine was 1 = -4, 2 = -9, 3 = -9 and 4 = -10; to norepinephrine it was 2 = +3, 4 = +6, 6 = +7 and 8 = +7. In hypertensive patients, the respective relations were 1 = +18, 2 = +44, 3 = +59 and 4 = +77; and 2 = +39, 4 = +54, 6 = +76 and 8 = +98. Group differences were highly significant. In each of these circumstances, the driving pressure across the lungs was significantly augmented in the hypertensive but not the normotensive group. Both epinephrine and norepinephrine have a vasoconstrictor influence on the lesser circulation as a consequence of vascular overreactivity. The opposite changes in resistance between normotensive and hypertensive subjects produced by epinephrine suggest that a constrictor vascular supersensitivity becomes active in the pulmonary circuit with the development of systemic high blood pressure.

Nitrendipine vs. long-acting nifedipine in mild, moderate and severe hypertension

Long-acting nifedipine and nitrendipine, a nifedipine analogue, have been proposed for single-drug therapy of hypertension. In this study we compared the two preparations in three groups (10 subjects in each group) of mild (group 1), moderate (group 2), and severe (group 3) hypertensives. Drugs were administered for seven days (20 mg every 8 hr), according to a randomized, double-blind, crossover design. Blood pressure and heart rate readings were taken hourly, from 8 A.M. to 7 P.M., for the duration of the trial. In group 1, pressure was lowered to normal levels by both compounds and did not recover in the interval between one dose and the other, so that it remained normal throughout the day. In group 2, from an average of 170/109, values were reduced by the two preparations to 140/90 mm Hg within two hours, and then they tended to recover. This tendency was interrupted by the next dose. Because of this pattern, compared with the placebo period, pressure was substantially reduced during the twelve hours of the day; however, for a certain span it remained higher than normal. In group 3, the immediate responses to the two drugs were similar (from an average of 208/130, pressure was lowered to an average of 170/95 mm Hg), and then it tended to rise again and recovery was faster with nifedipine. Although pressure was significantly reduced throughout the day by both preparations, normotension was never achieved in this group. Neither drug induced a tachycardia reaction, altered renal or cardiac function, or affected body weight or plasma renin activity. The tendency to produce dependent edema was less pronounced with nitrendipine. In conclusion, these calcium channel antagonists were equally effective in mild and moderate hypertension, while in the severe from the action of nitrendipine was more persistent. Within the limits of the drug regimens used in this study, it seems that both preparations as monotherapy may be satisfactory in mild, questionable in moderate, and inadequate for severe hypertension, although the action of nitrendipine is more lasting.

Ethanol administration in the rat decreases prostacyclin production by isolated brain microvessels

The effects of short- and long-term ethanol administration to rats on basal levels and formation of prostacyclin (PGI2) measured as 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), and on lipid class content and fatty acid composition of isolated brain microvessels (BMV) were studied. After acute treatment (2 h, at the peak of plasma ethanol concentration) basal 6-keto-PGF1 alpha levels in BMV and release on incubation were reduced to 50% of control values. After chronic administration (15 days), PGI2 release was reduced to about 40% of control values, without changes in basal levels. Total lipid, phospholipid, and cholesterol levels in BMV, measured after prolonged administration of alcohol, were not modified. Also, only minor changes in the fatty acid composition of individual phospholipid classes were detected. The observed reduction of PGI2 synthesis in BMV thus could not be related to changes of the fatty acid precursor pool in the preparation. Precursor release and/or the biosynthetic pathways may be affected by ethanol administration.

Effects of CDP-choline on platelet aggregation and the antiaggregatory activity of arterial wall in the rat

The effects of the acute (250 mg/kg) and chronic (250 mg/kg for two weeks) treatments with CDP-choline on platelet aggregation and thromboxane formation and on the platelet antiaggregatory activity of thoracic aorta, have been studied in the rat. The acute administration resulted mainly in reduced platelet reactivity to aggregating agents, with no change of platelet thromboxane formation. The antiaggregatory activity of aortic walls was also concomitantly reduced. After chronic treatment, the major effect was a greater antiaggregatory activity of the vessel wall in respect of the control values, whereas platelet function was not affected. CDP-choline treatment, thus exerts favourable effects especially in the acute treatment, by reducing platelet reactivity.

Dietary interventions in north Karelia, Finland and south Italy. Modification of thromboxane B2 formation in platelets of male subjects only

The effects of dietary interventions, based on changes of total fat, saturated fatty acids and cholesterol contents and of the polyunsaturated/saturated (P/S) fatty acid ratio of the diet, were studied in normal male and female subjects, living in North Karelia, Finland, and South Italy. In North Karelia the increase of P/S ratio (from 0.15 to 1.2) of the diet for a 6-week period resulted in reduced thromboxane B2 (TxB2) production by collagen-stimulated platelets only in male subjects, whereas plasma total, LDL and HDL cholesterol were reduced in both sexes. After a 6-week return to the original diet, plasma lipid levels were restored in all subjects. In the South Italy study, changes in platelet TxB2 production were observed only after return to the original diet in male subjects. Total and LDL cholesterol were significantly increased during the dietary intervention and returned toward baseline levels after switch back to the original diet. These data indicate that the increase of the P/S ratio in the diet reduces platelet TxB2 formation only in men.

Diets rich in saturated, monounsaturated and polyunsaturated fatty acids differently affect plasma lipids, platelet and arterial wall eicosanoids in rabbits

New Zealand male rabbits, on a moderate dietary fat intake (10.2% w/w) received, as the major dietary lipid, butter, olive oil and corn oil, respectively, for a period of 8 weeks. At the end of the dietary treatment, plasma total cholesterol was significantly decreased in the corn oil group, compared to butter, whereas the olive-oil-consuming rabbits had an intermediate cholesterolemia; the corn oil and olive oil groups had significantly elevated high-density lipoprotein (HDL) cholesterolemia, compared to the butter group. Maximal platelet aggregability, with collagen and arachidonic acid, did not appear to differ in the three treatment groups. Thromboxane B2 release in the sera of treated rabbits was slightly higher after corn oil administration. The arterial release of prostacyclin (PGI2), tested by perfusing platelet-rich plasma through the aorta of donor rabbits, was lowest in the corn oil group. Corn oil is the most effective dietary fat in reducing cholesterolemia, but it may also reduce PGI2 release from arteries. Butter has the most unfavorable effect on lipidemia and HDL-cholesterol, whereas dietary olive oil shows an intermediate lipid-lowering activity but preserves arterial PGI2 production.

Platelets from aged rats aggregate more, but are more sensitive to prostacyclin

The balance between vascular eicosanoids has been explored in young (1 month of age) and aged (11 month of age) rats. PRP from mature rats was more reactive to collagen (lower threshold, greater amplitude of aggregation curve and higher TxB2 formation) than PRP from young animals. Release of 6-keto-PGF1 alpha from PRP-perfused isolated aortas (pg@ul) was higher and the inhibition of PRP aggregation after perfusion correspondingly greater, in mature rats. Platelets from aged rats were more sensitive to exogenous prostacyclin (higher inhibition of aggregation and greater accumulation of cAMP). The fatty acid compositions of plasma and platelet lipids were not different in the two age groups. Compensatory mechanisms were operating in the aged rats, counteracting the greater platelet aggregability with higher vascular prostacyclin production and greater sensitivity of platelets to this eicosanoid.

Pulmonary vascular overreactivity in systemic hypertension. A pathophysiological link between the greater and the lesser circulation

This study was undertaken to test whether the emphasized systemic vasomotion during sympathetic activation in hypertension is shared by the pulmonary circulation. To this end, 10 normotensive and 29 primary hypertensive subjects were investigated during adrenergic stimulation by mental arithmetic and cold pressor test. Both stimuli induced a systemic pressor reaction in both groups, which was mediated through an increase in cardiac output and a mild reduction in vascular resistance during arithmetic and through a predominant rise in systemic vascular resistance during cold. Each of these changes was emphasized in the hypertensive population as compared with the normotensive one. Pressure in the pulmonary artery remained unchanged during cold and was slightly raised (systolic) during arithmetic in normotensive subjects. On the contrary, in hypertensive subjects systolic and diastolic pulmonary pressures were consistently augmented by both stimuli, and pulmonary arteriolar resistance (dyn sec cm-5) rose from 92 in the baseline to 125 (p less than 0.01) during arithmetic and to 124 (p less than 0.01) during the cold test. This reaction is interpreted as reflecting a neurally mediated vasoconstriction and not as the consequence of mechanical or chemical changes, since no difference was observed in pulmonary wedge pressure, pleural pressure, arterial blood gas levels, and pH between controls and hypertensive subjects in the steady state and during either stressful stimulation. Baseline pulmonary arteriolar resistance was also found to correlate positively with systemic vascular resistance in the hypertensive group. When pressure changes occurred, the time course was similar in the two circuits; resistance increased to a proportionally similar degree in the two districts during the cold stimulus.(ABSTRACT TRUNCATED AT 250 WORDS)

[Nifedipine as a vasodilator antihypertensive with a rapid action]

On occasion, blood pressure rises so precipitously and severily, or the clinical setting in which hypertension occurs is so critical, that prompt pressure lowering becomes crucial to prevent disabling, or even lethal complications. Such hypertensive emergencies more commonly complicate the accelerated phase of untreated or poorly treated hypertension of various etiologies. There is also a group of conditions that qualify as hypertensive emergencies not so much because of the actual height of the pressure, but rather because of complicating disorders that make even moderate pressure elevation harmful. These include aortic dissection, intracranial bleeding and acute left ventricular failure. Two fundamental concepts in the management of hypertensive emergencies are: immediate and effective therapy is required and takes precedence over time-consuming diagnostic procedures; the choice of the drugs will depend on how their time course of action and hemodynamic and metabolic effects meet the needs of the clinical situation. It is well proven that nifedipine reduces Ca-dependent vascular smooth muscle tone by direct interference with transmembrane Ca supply and thereby counteracts every kind of contractile tension development of the vascular wall: the higher the wall tension, the easier relaxation in induced by a given concentration of the compound. Because of this, it has become quite clear from recent studies that: nifedipine is a potent antihypertensive agent.(ABSTRACT TRUNCATED AT 250 WORDS)