The Wiskott-Aldrich syndrome: studies of platelets, basophils and polymorphonuclear leucocytes

Platelets, basophils and neutrophils from a patient with the Wiskott-Aldrich syndrome (WAS) were exposed to stimuli that activate specific membrane receptor or directly initiate biochemical events (e.g. the Ca2+ ionophore A23187 and ionomycin or arachidonic acid). Platelets from this patient did not aggregate in response to ADP, collagen, thrombin or adrenaline, which activate specific membrane receptors. Platelet aggregation, however, was normal in response to compound A23187, ionomycin or exogenous arachidonic acid. Histamine release from basophils of the WAS patient was normal in response to anti-IgE, a formylated peptide (f-met peptide), and to A23187. Similarly, the release of the lysosomal enzymes, beta-glucuronidase and lysozyme, from neutrophils of the WAS patient in response to serum treated zymosan (Zx), f-met peptide, and A23187 was not significantly different from that of his parents and 13 normal donors. These results suggest that the primary defect in WAS is selectively present in platelets and is located in a biochemical step between receptor activation and Ca2+ influx and/or initiation of arachidonate metabolism.

IgE-mediated activation of human heart in vitro

We used human cardiac tissue from the right atrial appendages of patients undergoing corrective heart surgery to study content and de novo synthesis of mediators in the human heart. Human heart tissue contained 1.7 +/- 0.1 micrograms/g wet weight of histamine (mean +/- S.E.M.) and spontaneously produced 6-keto-PGF1 alpha (38.4 ng/g wet weight/min), PGF1 alpha (1.9 ng/g wet weight/min), PGE (1.7 ng/g wet weight/min) and thromboxane B2 (TxB2) (1.7 ng/g wet weight/min). Spontaneous release of PGD2, leukotriene C4 and histamine was negligible. Rabbit anti-human IgE (1-10 micrograms/ml) dose-dependently induced the release of histamine (5 to 15% of the total histamine content) and of PGD2 (5 to 100 ng/g of wet tissue). The effect of anti-IgE was dose-related and reached a maximum after 30-45 min of incubation. A significant linear correlation (rs = 0.90; p less than 0.001) was found between de novo synthesis of PGD2 and the secretion of histamine induced by anti-IgE challenge of human heart. These results support the concept that PGI2 is the main, but not the sole, product of arachidonic acid metabolism synthesized by human heart in vitro. Additionally, anti-IgE challenge of human heart in vitro induces the release of histamine and PGD2. The local concentrations of these mediators appear high enough to play some role in the modulation of several cardiac functions in vivo.

Physiological concentrations of zinc inhibit the release of histamine from human basophils and lung mast cells

We have previously shown that physiological concentrations of zinc (congruent to 7 X 10(-6) M) inhibit the release of histamine from human basophil leukocytes (Marone et al., J. Pharmacol. Exp. Ther. 217: 292, 1981). In these experiments we compared the effect of zinc chloride on the release of chemical mediators from human basophils and mast cells isolated from human lung. Preincubation (5 min, 37 degrees C) of human basophils and lung mast cells with zinc chloride (10(-6)-3 X 10(-5) M) caused dose-related inhibition of histamine and peptide leukotriene C4 (LTC4) release induced by anti-IgE. Increase Ca2+ concentrations (0.3 to 6 mM) in the extracellular medium completely reversed the inhibitory effect of zinc on anti-IgE-mediated histamine secretion. Zinc chloride was a competitive antagonist of the action of Ca2+ in histamine secretion induced by anti-IgE with a dissociation constant (Kd) of about 10(-5) M in both the basophil and mast cell systems. Thus physiological concentrations of zinc inhibit the release of histamine from human basophils and lung mast cells, presumably by blocking Ca2+ uptake induced by anti-IgE activation.

Noninvasive techniques in clinical pharmacology. Time intervals in assessment of vasodilators in coronary artery disease

We enrolled 15 male volunteers with angiographic evidence of coronary artery disease (CAD) to investigate the effects of sublingual administration, on different days, at random, of placebo and three drugs with different action such as isosorbide dinitrate, nifedipine and molsidomine. We recorded simultaneously electrocardiogram, phonocardiogram and carotid pulse at paper speed of 100 mm/s; blood pressure was measured by auscultatory method. We calculated the systolic time intervals (STI) being noninvasive indices of left ventricular function and the ratio of diastolic time to heart rate (%D), well related to coronary blood flow in patients with severe obstructive lesions. Placebo decreased heart rate (HR) without effects on STI or %D. Isosorbide dinitrate induced a prolonged pre-ejection period (PEP) (by decreasing preload), tachycardia and a significantly decreased %D, suggesting a fall in coronary blood flow time. Nifedipine decreased diastolic blood pressure and values of PEP (by decreasing afterload) without effects on %D. Finally, molsidomine prolonged PEP (by decreasing preload) without reflex induced tachycardia and changes of %D. In conclusion, mechanocardiography can be useful in noninvasive assessment of vasodilators in CAD patients.

Human basophil releasability. I. Age-related changes in basophil releasability

Releasability of human basophils (i.e., the response to a standard stimulus) is an important parameter in several pathophysiologic conditions. We studied the IgE (anti-IgE)- and non-IgE-mediated (f-met peptide and Ca2+ ionophore A23187) releasability of human basophils obtained from 63 normal donors whose ages ranged from 1 to 86 years. The maximum percent of histamine release induced by anti-IgE was significantly correlated (rs = 0.57; p less than 0.001) with the age of donors. The sensitivity to a standard concentration of anti-IgE (3 X 10(-2) mcg/ml) was also correlated with the age of cell donors (rs = 0.68; p less than 0.001). In the population of 63 donors tested, the maximum percent of histamine release and the cell sensitivity to anti-IgE appeared to be independent of the serum concentration of IgE. However, we found a positive correlation (rs = 0.55; p less than 0.05) between serum IgE level and anti-IgE-induced histamine release in the group less than 20 years of age. In contrast, a negative correlation (rs = -0.32; p less than 0.05) between serum IgE level and anti-IgE-induced histamine secretion was found in the group greater than 21 years of age. The maximum percent of histamine release induced by f-met peptide and Ca2+ ionophore A23187 appeared to be independent to both the age of the donors and the serum IgE level.(ABSTRACT TRUNCATED AT 250 WORDS)

Reversal of left ventricular hypertrophy following treatment with beta-blockers: experience with tertatolol

Hypertrophy in response to increasing blood pressure in primary hypertension leads to important functional consequences for the left ventricle. In fact, the progression of hypertensive heart disease, from an adaptive left ventricular hypertrophy with compensated ventricular function to severe hypertrophy with left ventricular failure, has been long thought to be related to the severity and duration of hypertension. Antihypertensive treatment seems to prevent or minimize the occurrence of left ventricular hypertrophy, but questions arise as to whether this therapy is also able to restore normal hemodynamic conditions, or at least to minimize the hemodynamic abnormalities. This review aims at summarizing current knowledge on the effects of the antihypertensive treatment with beta-blockers, including tertatolol, on hypertension-induced left ventricular hypertrophy. The pathogenetic mechanisms underlying the cardiovascular changes associated with hypertension are discussed. A decrease in left ventricular wall thickness as well as in left ventricular mass has been reported in most of the studies performed with different types of beta-adrenergic blocking agents. The extent of this reduction seems to be related not only to the fall in systemic blood pressure, but also to a decrease in sympathetic stimulation. With regard to the functional consequences of hypertension, the reversal of left ventricular hypertrophy following antihypertensive treatment with beta-blockers is usually associated with an improvement in left ventricular performance. This phenomenon can hardly be ascribed to the direct effects of beta-blocking agents. It is more likely to be related to the concomitant reduction in the afterload and to the improved left ventricular compliance, associated with a decrease in left ventricular wall thickness.

Myocardial hypertrophy in rats exposed to simulated high altitude

Myocardial hypertrophy in Sprague-Dawley adult rats exposed to hypobaric hypoxia (0.40 atmosphere of air/18 h daily for 7 days) in a hypobaric chamber was investigated. Changes in the myocardial mass were evaluated on the basis of the dry heart weight and expressed as mg/100 g of total body weight (mean +/- SEM). Data are presented indicating that: chronic hypobaric hypoxia causes a significant degree of myocardial hypertrophy in rats; hypertrophic process involves both ventricles (the right more than the left); removal of the hypoxic stimulus leads to the disappearance of hypertrophy when evaluated as an increase in dry heart weight; hypoxia affects the synthesis of a significant amount of connective tissue in the left ventricle, which is not exposed to pressure load. The rôle of neurohumoral factors (i.e., adrenergic stimulation and catecholamines) in the development of the ventricular hypertrophy is suggested.

Asymptomatic transient ST changes during ambulatory ECG monitoring in diabetic patients

The reported higher incidence of painless myocardial infarction in diabetic patients suggests that asymptomatic transient myocardial ischemia may also be frequent in diabetes. To explore this possibility 51 subjects with type II diabetes, aged 43 to 71 years (mean +/- SEM 56 +/- 8), 70 nondiabetic patients with coronary artery disease (mean age 55 +/- 5), and 40 nondiabetic patients without overt coronary disease (age 54 +/- 9) were studied. Thirty-eight of the 51 diabetic patients (74%) had evidence of associated coronary disease and 19 (37%) had evidence of previous myocardial infarction. All subjects underwent continuous 24-hour ambulatory ECG monitoring. In 18 of 51 diabetic patients 93 episodes (73% of the total number) of asymptomatic ST segment changes were recorded; the total number of symptomatic episodes was 36, and they were observed in seven patients (27%). Forty-eight (60%) asymptomatic and 32 symptomatic episodes of significant ST changes were found in nondiabetic patients with coronary artery disease. When patients with previous myocardial infarction were examined separately, asymptomatic episodes of significant ST changes were observed in 10 of 19 diabetic patients and in 5 of 25 nondiabetic patients with coronary artery disease (p less than 0.05). In an additional 28 diabetic patients who underwent exercise stress test, 15 exhibited an abnormal ECG response; however, only five of them (33%) were symptomatic. This study suggests that the incidence of transitory myocardial ischemia, as assessed by ambulatory ECG monitoring and exercise stress test, is higher in type II diabetic patients than in nondiabetic control subjects with coronary artery disease.

24-hour blood pressure recording in patients with orthostatic hypotension

Continuous intra-arterial blood pressure measurement and electrocardiograms were obtained in two ambulatory patients with orthostatic hypotension due to autonomic dysfunction. Systolic and diastolic arterial pressure presented marked variations which took place mainly during the day and were related to several physical activities; however, marked falls in blood pressure were also observed during sleep and at the moment of arousal. A peak incidence of hypotensive events was found in the afternoon, mainly in the hours following the afternoon meal. Recording was repeated after 3 weeks of treatment with propranolol, 40 mg t.i.d. In patient 1, beta blockade drastically reduced the number and severity of hypotensive episodes, while propranolol failed to control blood pressure in patient 2, who experienced a higher number of hypotensive events during treatment. Findings of this study may be relevant to the management of patients with orthostatic hypotension and should contribute to a more accurate characterization of blood pressure profile in autonomic dysfunction.

Histamine release from human basophils by pepstatin A

Pepstatin A, a pentapeptide isolated from cultures of actinomycetes, induced histamine secretion from human basophils in the concentration range of 3 X 10(-7) to 10(-4) M. The characteristics of this reaction were similar to those of f-met-peptide-induced histamine release: pepstatin A-induced release required Ca2+ and the release reaction was complete within 2 min at 22 or 37 degrees C, but did not occur at 4 degrees C. Release by both pepstatin A and f-met-peptide was reversibly inhibited by two non-releasing analogs of f-met-peptide, CBZ-Phe-Met and BOC-Met-Leu-Phe. Further, there was complete cross-desensitization between pepstatin A and f-met-peptide, while cells desensitized to pepstatin A released normally with anti-IgE and vice versa. A variety of pharmacological agents had similar effects on both pepstatin A and f-met-peptide-induced release (e.g., no enhancement with D2O; marked enhancement with cytochalasin B). We suggest that pepstatin A induces histamine release from human basophils by activating a cell surface receptor(s), also activated by the synthetic tripeptide f-met-peptide.

Indenolol: a new antihypertensive agent: efficacy, toxicity, and hemodynamic effects in a crossover double-blind study with metoprolol

The antihypertensive efficacy of a new agent, indenolol, was compared with that of the well-established antihypertensive drug, metoprolol, and its hemodynamic effects were investigated using echocardiography. Eighteen hypertensives completed a double-blind, crossover, randomized study using indenolol and metoprolol. Two four-week courses with indenolol or metoprolol were preceded and followed by a two-week placebo period; the total duration of the study was 14 weeks. Indenolol proved to be significantly more effective than metoprolol in decreasing blood pressure values at rest (P less than .05). Furthermore, three patients that failed with metoprolol were successfully treated with indenolol. Both drugs induced a significant decrease in cardiac output that was mediated mainly through a reduction in heart rate, because stroke volume, left ventricle circumferential fiber shortening velocity, and ejection fraction were not significantly reduced by either drug. However, after indenolol, a significant direct relationship was found between the basal values of both cardiac output (r = .809) and total peripheral resistance (r = .800), and the reduction of these parameters. On the contrary, after metoprolol only, the correlation between the basal value of cardiac output and its reduction was significant (r = .790).

Participation of endogenous catecholamines in the regulation of left ventricular mass in progeny of hypertensive parents

To investigate whether adrenergic activity is a determinant of left ventricular hypertrophy in human hypertension, in each of 10 normotensive subjects with two hypertensive parents we have examined the relationship between changes in echocardiographic parameters of left ventricular anatomy and those in circulating catecholamine levels induced by three, 3 week periods of different sodium and potassium intakes. A high sodium-normal potassium regimen induced a significant reduction in upright plasma norepinephrine (from 599 +/- 89 to 379 +/- 45 pg/ml, p less than .01) and in posterior wall (PWT) and interventricular septal (IVST) thickness, as well as in the left ventricular mass index (LVMi). Changes in upright plasma norepinephrine concentrations correlated with those in IVST (r = .822, p less than .01) and in LVMi (r = .833, p less than .01). A low sodium-normal potassium diet resulted in increases in supine and upright plasma norepinephrine levels (from 356 +/- 44 to 488 +/- 89 pg/ml, p less than .001; and from 565 +/- 42 to 744 +/- 33 pg/ml, p less than .01) as well as increases in IVST and LVMi (from 97 +/- 7 to 107 +/- 7 g/m2, p less than .001). The changes in norepinephrine levels in supine and upright subjects correlated with changes in IVST (r = .836, p less than .01 and r = .796, p less than .01) and in LVMi (r = .931, p less than .001 and r = .947, p less than .001). No significant change in plasma catecholamine concentrations or in PWT, IVST, or LVMi was detected after a low sodium-high potassium regimen.(ABSTRACT TRUNCATED AT 250 WORDS)

Carotid sinus reflex control of coronary blood flow in human subjects

Systemic and coronary hemodynamics were assessed before and during a reduction in carotid transmural pressure. This reduction was induced by means of a pneumatic neck chamber in 15 normal subjects and 15 hypertensive patients with a normal coronary arteriogram. A reduced baroreflex responsiveness was demonstrated in hypertensive patients as compared with normal subjects by evaluating both the reflex bradycardia evoked by intravenous administration of phenylephrine and the reflex increase in blood pressure during carotid sinus hypotension. In normal subjects, the reduction in carotid transmural pressure induced a significant increase in mean blood pressure, total peripheral resistance, cardiac output, heart rate, coronary vascular resistance, coronary blood flow assessed by the continuous thermodilution method and myocardial oxygen consumption. In hypertensive patients, the same stimulus significantly increased mean blood pressure, cardiac output, heart rate and coronary blood flow while no significant change was detected in coronary vascular resistance and myocardial oxygen consumption. The increase in mean blood pressure, total peripheral resistance and cardiac output was significantly higher in normal subjects than in hypertensive patients. These results suggest that in normal subjects carotid sinus hypotension evokes reflex coronary vasoconstriction, whereas this response is blunted in hypertensive patients with reduced baroreflex sensitivity.

Late phase of nitroglycerin-induced coronary vasodilatation blunted by inhibition of prostaglandin synthesis

In chloralose-anesthetized dogs with the left circumflex coronary artery perfused at constant flow, the effects of increasing doses of indomethacin or naproxen on the coronary and systemic hemodynamic responses to a 5 microgram intracoronary injection of nitroglycerin (NTG) were evaluated. The integrated areas of NTG-induced coronary vasodilatation were reduced after administration of indomethacin or naproxen. The extent of this reduction was increased progressively by augmenting the dose of indomethacin and naproxen up to 1.5 and 7 mg/kg, respectively. We also assessed the extent of cyclooxygenase inhibition induced by indomethacin or naproxen through the radioimmunoassay of thromboxane B2, which reflects thrombin-induced activation of platelet thromboxane A2 production during whole blood clotting. The level of inhibition progressively increased and complete inhibition was attained with 1.5 mg/kg indomethacin and 7 mg/kg naproxen. Further increase in dosage failed to induce further reduction of integrated areas of coronary vasodilatation, and a correlation was found between the extent of the reduction of the integrated areas of coronary vasodilatation and the dose of indomethacin (r = .828, n = 35, p less than .001) or naproxen (r = .729, n = 35, p less than .001). Finally, the NTG-induced maximum fall in coronary perfusion pressure remained unmodified after inhibition of prostaglandin synthesis, but there was a faster return of the perfusion pressure to the basal value.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for an adenosine A2/Ra receptor on human basophils

5'-N-ethylcarboxamideadenosine (NECA) greater than 2-chloroadenosine greater than adenosine greater than (-)-N6-(R-phenyl-isopropyl)-adenosine greater than (+)-N6-(S-phenylisopropyl)-adenosine, in that order of potency, inhibited in vitro antigen-induced histamine release from human basophils in a dose-dependent fashion. Inhibition occurred only during the first stage of antigen-induced histamine release and the nucleosides failed to inhibit the release caused by the Ca2+ ionophore, A23187. 6-nitrobenzylthioinosine and dipyridamole, which inhibit adenosine uptake, and erythro-9-(2-hydroxy-3-nonyl)adenine, which blocks adenosine metabolism, did not impair the inhibition caused by NECA and adenosine. 8-phenyltheophylline and theophylline, two competitive antagonists of adenosine receptors, blocked the inhibition caused by NECA and adenosine. These data suggest that NECA and other adenosine analogs activate a specific cell surface adenosine receptor which possesses properties similar to those of an adenosine A2/Ra receptor.

Evaluation of the efficacy of slow-release nifedipine in systemic hypertension by ambulatory intraarterial blood pressure monitoring

We assessed the effect on blood pressure of administration of slow-release nifedipine tablets (20 mg) by continuous intraarterial blood pressure monitoring (Oxford system) in 10 patients with untreated essential hypertension. Blood pressure was recorded under control conditions and during nifedipine therapy. During each monitoring period patients were instructed to perform various types of exercise. The initial dose of nifedipine was 20 mg twice a day (8:00 a.m. and 8:00 p.m.). For patients in whom arterial pressure control was not achieved, the dose of the drug was increased at weekly intervals, first to 40 mg in the morning and 20 mg at night and then to 40 mg twice a day. The average daily dose was 52 mg. Nifedipine twice a day significantly reduced systolic and diastolic blood pressures both during the day and during the night. The rise in blood pressure due to dynamic or isometric exercise or to mental testing was blunted. Heart rate did not change. Orthostatic hypotension was not observed, and there were only minor side effects, which did not require withdrawal of the patient from the trial. Bioavailability of nifedipine from this preparation was satisfactory, as shown by plasma concentrations which remained constantly in the therapeutic range. Thus, slow-release nifedipine given twice a day represents an effective treatment in patients with essential arterial hypertension. The reduced frequency of administration required may improve patient compliance with this treatment.