Calcium channel blockers--are they diuretics?

Seven untreated patients with essential hypertension but without target organ damage were admitted to hospital. Urine was collected the following day from 08.00 to 13.00 h, 13.00 to 18.00 h, and 18.00 to 08.00 h. The protocol was repeated the next day following 30 mg oral nicardipine. Intra-arterial blood pressure (IABP), plasma volume, and plasma renin activity (PRA) also were measured daily. Following the single-dose study, the patients were treated as outpatients and received oral nicardipine 20, 30, or 40 mg four times daily. They were readmitted 2 months later for further study, at which time the protocol was repeated. Urine output between 08.00 and 13.00 h significantly increased after the single- and multiple-dose studies. Following the single-dose study, this diuresis was associated with a natriuresis. Urine output increased over the 24 h following multiple-dose treatment, but this increase was not statistically significant. During the multiple-dose 24 h study, there was an increase in urinary potassium (P less than 0.05). Mean IABP was reduced significantly after the single- and multiple-dose studies (P less than 0.02 and less than 0.05, respectively). During the study, there were no significant changes in plasma volume, weight, or plasma renin activity.

Selenium responsive myositis during prolonged home total parenteral nutrition in cystic fibrosis

The need for routine supplementation of total parenteral nutrition solutions with selenium (Se) has not been clearly defined. Although clinical selenium deficiency in patients on prolonged total parenteral nutrition has been reported, it is rarely observed in the United States. We report a 19-year-old woman with cystic fibrosis who developed muscle pain and weakness after 3 months on total parenteral nutrition which was not supplemented with Se. Coincident with her onset of symptoms, markedly elevated serum creatine kinase values were observed compared to baseline levels. Subsequent evaluations revealed undetectable (less than 0.02 microgram/ml) serum and urine Se levels in this patient. In addition, electromyographic evidence of myositis and nonspecific membrane irritability was documented. Therapy with oral Se rapidly reversed her symptoms and normalized with serum creatine kinase values over a 10-day period. Prolonged treatment with Se was required to achieve normal values of Se in the serum. Patients with severe pancreatic insufficiency, such as cystic fibrosis, may be at risk for clinical Se deficiency if on prolonged total parenteral nutrition without supplementation. Elevated creatine kinase levels should alert physicians to the possibility of Se deficiency in such patients.

The Birmingham Trial of permanent pacing in patients with intraventricular conduction disorders after acute myocardial infarction

Patients surviving 2 weeks after myocardial infarction who had persistent conduction disorder (right bundle branch block alone or associated with left anterior or posterior hemiblock [LPH] or LPH alone) were allocated at random to permanent pacing or control groups. Throughout follow-up, up to 5 years, there was no significant difference in survival: at 2 years 14 of 23 (61%) of paced patients had died compared with 11 of 27 (41%) control patients. Progression of conduction disorder was not observed and measurement of infranodal conduction time (HV interval) did not predict outcome. Ventricular tachyarrhythmias were an important cause of death in these patients and pacing appears to offer no benefit.

Influence of variation in dietary sodium intake on biochemical indices of sympathetic activity in normal man

The effects of variation in dietary sodium intake on biochemical indices of sympathetic activity were investigated in normal subjects. Sodium restriction for 7 days (mean urinary sodium excretion 21 mmol/day, s.e.m. = 4) increased supine plasma noradrenaline concentration significantly (1.78 nmol/l, s.e.m. = 0.23) compared to levels during medium sodium intake (1.31 nmol/l, s.e.m. = 0.14) and high sodium intake (1.35 nmol/l, s.e.m. = 0.25), when urinary sodium excretion averaged 186 (s.e.m. = 24) and 310 (s.e.m. = 43) mmol/l respectively. Plasma adrenaline concentrations did not vary significantly. During sodium restriction, the apparent release rate of noradrenaline increased significantly; noradrenaline clearance remained unchanged. No changes were observed in the heart rate response after beta-adrenoceptor stimulation with isoprenaline, suggesting that increased sympathetic activity during sodium restriction did not necessarily alter cardiac beta-receptor sensitivity. The responses to cardiac autonomic blockade with propranolol and atropine did not vary with sodium intake. These observations suggest that the sympathetic response to sodium restriction may not be generalized, excluding, in particular, the sympathetic nerves to the heart.

Baroreflex setting and sensitivity after acute and chronic nicardipine therapy

Intra-arterial pressure, baroreflex sensitivity and the baroreflex set point were measured in eight patients with essential hypertension during a control period and then after acute treatment (2 h after a 30 mg oral dose) and after chronic treatment (at least 2 months) with nicardipine hydrochloride, a calcium channel antagonist. Mean intra-arterial blood pressure fell after the acute treatment from 130 +/- 14 (SD) control to 118 +/- 11 mmHg, P less than 0.05, and after chronic treatment to 112 +/- 19 mmHg, P less than 0.05. Heart rate increased from 72 +/- 11 control to 81 +/- 16 beats/min, P less than 0.05, during acute treatment indicating activation of the baroreflex control mechanism, but returned to control values with chronic treatment (72 +/- 11 control vs 69 +/- 9 beats/min chronic), indicating a significant shift to the left of the baroreflex set point. There was no change in baroreflex sensitivity after either acute or chronic treatment (control 4.7, acute 4.3, chronic 5.1 ms/mmHg, P not significant for all values). Nicardipine significantly reduces mean intra-arterial pressure both acutely and chronically; the latter is associated with a return of the heart rate to control values due to resetting of the baroreflex control mechanism.

Feed associated haemorrhagic disorder in pigs accompanied by pancreatic lesions

The introduction of a new batch of feed to 400 pigs aged five to eight weeks resulted in 38 deaths and further morbidity associated with multiple haemorrhages. Signs abated within two days of withdrawal of the feed. Widespread haemorrhages were present in many tissues including the pancreas. Additional pancreatic lesions comprised focal necrosis, atrophy and fibrosis of exocrine tissue. The condition was reproduced experimentally in pigs and vitamin K protected mice against the injurious effects of the feed. The cause was not determined but it is speculated that more than one toxic factor and an imbalance of nutritional factors may have been present in the diet.

The effect of nifedipine on arterial pressure and reflex cardiac control

Nine patients with untreated essential hypertension (mean casual blood pressure 173/109 +/- 14/7 mm Hg) (+/- SD) were studied in the control state and after 16 weeks of treatment with nifedipine, 10 mg orally every 8 hours. Direct arterial blood pressure monitored continuously over 24 hours showed that nifedipine significantly reduced systolic and diastolic blood pressure throughout the day and the night. The variability of blood pressure was not altered by nifedipine therapy. There was no significant change in heart rate after nifedipine therapy. Chronic nifedipine therapy increased forearm blood flow and decreased forearm vascular resistance, consistent with its action as a vasodilator. The absolute blood pressure responses to tilt, handgrip and cold were reduced, but the percent increase in pressure was not altered by therapy. Plasma renin activity was not altered by chronic nifedipine therapy. At each study, the sensitivity and setting of the baroreflex response to i.v. phenylephrine was measured. After chronic nifedipine therapy there was resetting of the sinoaortic baroreflex and an increase in its sensitivity. Successful control of blood pressure with nifedipine led to a significant reduction in the left ventricular mass index.

Effect of environment on blood pressure: home versus hospital

The effect of environment on blood pressure was studied by recording intra-arterial pressure continuously in nine patients with essential hypertension during controlled periods of activity and rest at home and in hospital. Mean systolic pressure was higher at home (152 +/- 16 mm Hg) than in hospital (138 +/- 11 mm Hg, p less than 0.01), the difference being greatest during the period of activity (165 +/- 21 v 142 +/- 13 mm Hg, p less than 0.001); heart rates and diastolic pressures did not differ significantly at these times. Systolic pressure recorded by conventional sphygmomanometry was also higher at home (173 +/- 23 v 159 +/- 23 mm Hg, p less than 0.01), as was diastolic pressure (98 +/- 10 v 89 +/- 11 mm Hg, p less than 0.02). Systolic pressure was consistently higher at home, and this effect was independent of the pressure of an observer. This must be taken into consideration when assessing blood pressure and efficacy of treatment in hospital.

Cardiovascular response in black and white hypertensives

Sixteen untreated black patients with mild-to-moderate hypertension and no evidence of target organ damage were matched for age, sex, casual blood pressure (BP), and socioeconomic status with 16 white hypertensives. All patients were studied under standardized conditions in the hospital where they underwent continuous intraarterial ambulatory monitoring of BP and assessment of BP control mechanisms. BP characteristics over prolonged periods of recording were similar for both groups, as were sinoaortic baroreflex activity and pressor response to isometric and dynamic exercise and to cold. Fasting cholesterol and triglyceride levels in both groups were similar. Resting plasma renin activity (PRA) was significantly lower in blacks, but no difference was observed in resting plasma norepinephrine levels. Urinary excretion of NA+ and K+ was also similar in both groups. Thus, results showed that casual BPs matched for black and whites, and recorded over a prolonged period, were similar in pattern, variability, and response to pressor stimuli. It appears that, if BP contributes to the different patterns of morbidity in blacks and whites, it is more likely to be the actual level of BP rather than differences in BP characteristics.

Applications of multidimensional computer graphics in medical systems

Multidimensional computer graphics are demonstrated in two medical systems applications in this paper. First, multidimensional computer graphics are utilized for descriptive purposes to show the differences among 10 physician specialty groups for multivariate data available at admission to medical school. Second, multidimensional computer graphics are demonstrated as a method that can be used for screening school applicants. The novel method utilized to represent multivariate data requires the plotting of a face. Each feature of a face--for example, face height or ear diameter-can be utilized to represent a different dimension of multivariate data. Each face then represents a vector whose elements are the mean values of multiple variables, or it represents a multivariate observation.

Assessment of left-ventricular mass and its response to antihypertensive treatment

50 patients with mild to moderate essential hypertension underwent M-mode echocardiography and continuous intra-arterial ambulatory monitoring of blood pressure. Indices of left-ventricular (LV) mass were derived from echocardiographic data by standard formulae. 43 of the patients were followed up for 12+/-7 months with repeat M-mode echocardiography, and casual blood-pressure measurements. 25 of these patients received antihypertensive therapy and 18 were untreated. Mean 24 h systolic blood pressure was significantly correlated with echocardiographic LV mass; mean 24 h diastolic blood pressure was also correlated, but the relation was weaker. In the treated group there was a significantly greater fall in blood pressure and LV mass index than in the untreated group, and there was a significant correlation between the fall in systolic blood pressure and the fall in LV mass index in the treated group. Systolic blood pressure appears to be an important factor in the pathogenesis of LV hypertrophy, and in hypertensive patients changes in LV mass assessed by echocardiography correlate with changes in blood pressure.

Protein Malnutrition and complement activity in guinea pigs, germ-free and conventional rats

Malnutrition produces a pronounced effect on the complement system of man and animals. There is little information, however, to indicate whether individual complement components are affected at different stages of age. In the following studies, we have demonstrated that in guinea pigs and in both conventional and germ-free rats, protein malnutrition adversely affects the complement system. The levels of complement components C2 and C3 are suppressed by protein malnutrition at an early stage while C4 and C8 are less affected by malnutrition. Experiments in germ-free animals demonstrated that decreased complement component levels can be directly associated with decreased synthesis and/or secretion of components. In conventional animals, further reductions in complement levels could occur as a result of infection associated with malnutrition.

Effects of chronic beta-adrenoceptor antagonism on plasma catecholamines and blood pressure in hypertension

Plasma catecholamines were measured before and after treatment with beta-adrenoceptor antagonists in 17 hypertensive patients. Chronic treatment with beta-adrenoceptor antagonists caused substantial reductions in heart rate and intra-arterial blood pressure recorded continuously during ambulation. Before treatment, a quantitative relationship was observed between plasma norepinephrine and blood pressure and heart rate during a variety of activities; a similar relationship was also observed after chronic treatment five of six patients, suggesting that plasma norepinephrine remains an index of sympathetic activity despite the influence of beta-adrenoceptor antagonism. After treatment, plasma norepinephrine tended to be higher at any level of blood pressure, although not significantly so. Chronic treatment caused no significant change in mean resting plasma levels of norepinephrine and epinephrine. During exercise, plasma norepinephrine and epinephrine levels were significantly elevated above control after acute but not after chronic treatment. These observations do not support the hypothesis that beta-adrenoceptor antagonist drugs lower blood pressure in hypertensive man through a sympatholytic mechanism in he central nervous system or at peripheral presynaptic receptors.

Plant stress detection by remote measurement of fluorescence

Chlorophyll fluorescence of mature lemon trees was measured with a Fraunhofer line discriminator (FLD). An increase in fluorescence was correlated with plant water stress as measured by stomatal resistance and twig water potential.

Changes in plasma noradrenaline and adrenaline during isometric exercise

1. Plasma noradrenaline and adrenaline were measured radioenzymatically in twelve hypertensive and four normotensive subjects before and during handgrip. In the resting arm (n=11), plasma noradrenaline increased by 17% (P<0.01) and plasma adrenaline by 27% (P<0.001). In the exercising arm, plasma adrenaline increased by 97% (P<0.005) but the mean increase of noradrenaline of 10% was not significant (P>0.1). 2. The noradrenaline response suggests a small and variable sympathetic adrenergic response; the significant difference (P<0.05) in adrenaline responses between resting and exercising arms may reflect local variation in tissue clearance.

Factors determining direct arterial pressure and its variability in hypertensive man

Intra-arterial pressure was recorded continuously in 26 patients with uncomplicated essential hypertension under standardized conditions. Recordings were analyzed beat by beat to obtain mean pressures and variability, expressed as the standard deviation of the frequency histogram. The major factors influencing variability were the level of pressure and the intensity of physical activity; systolic variability increased with progressive impairment of sino-aortic baroreflexes. Diastolic pressure increased with the level of sympathetic activity as reflected by plasma norepinephrine levels. After allowance for the decrease of plasma renin activity (PRA) with age, direct relationships were observed between PRA (log values) and the level of pressure and systolic variability; plasma angiotensin II values did not correlate. Systolic variability increased with the systolic response to cold but was unrelated to the response to dynamic or isometric exercise. Variability also tended to increase with obesity and was unrelated to age, sex, or race.

Comparison of once and twice daily administration of acebutolol in hypertension

1 Thirteen hypertensive patients completed a double-blind comparison of placebo, acebutolol 200 mg twice daily and acebutolol 400 mg once daily, administered for 4 weeks in random order. 2 Blood pressure and heart rate were significantly reduced by both acebutolol treatments. The mean reduction of resting pressure 12 h after 200 mg twice daily (12/7 mmHg) was similar to that 24 hr after 400 mg once daily (13/9 mmHg). 3 Compared to placebo, reductions in exercise heart rate and systolic pressure at 12 h after 200 mg twice daily and 24 h after 400 mg once daily were significant and similar. 4 Beta-adrenoceptor antagonism was also assessed by inhibition of the heart rate response to sublingual glyceryl trinitrate taken in the standing position. Both acebutolol treatments reduced the response; the reduction after twice daily treatment (mean 25 beats/min) was significantly greater than after once daily treatment (mean 19 beats/min). 5 There was no difference in blood pressure control between acebutolol administered once and twice daily in a total daily dose of 400 mg.

The influence of physical activity on arterial pressure during ambulatory recordings in man

1. Ambulatory blood pressure recordings were made over a 48 h period on six hypertensive patients. The conditions of study were standardized, particularly with regard to physical activity, and during one period of each day the patients were randomly allocated to be active or inactive. 2. Results show that blood pressure was highest during physical activity and lowest during sleep. There was no significant difference between the arterial pressures measured during the same physical activities carried out at the same time each day. However, during the same time on consecutive days when activity was randomized, there was a significant difference between the pressure recordings during physical activity compared with those during inactivity. Heart rate changes showed a similar trend during the randomized period. 3. Physical activity and sleep have a profound effect on continuous arterial blood pressure recordings and these are independent of time alone. These observations should be taken into account when using this ambulatory system to assess hypotensive therapy.

Sequential changes in plasma noradrenaline during bicycle exercise

1. Forearm venous plasma noradrenaline, heart rate and intra-arterial blood pressure were measured sequentially during and after upright bicycle exercise in five normotensive and six hypertensive patients. 2. Plasma noradrenaline increased significantly between 4 and 8 min during exercise. 3. On stopping exercise blood pressure and heart rate decreased rapidly whilst plasma noradrenaline increased in each subject to reach a maximum at a median time of 108 s after exercise. 4. Plasma noradrenaline decreased in five of six normotensive patients between the end of exercise and 2 min after exercise performed in the supine position. 5. Evidence in favour of a reflex increase in sympathetic activity after upright exercise is discussed.

Plasma noradrenaline concentrations at different vascular sites during rest and isometric and dynamic exercise

1. Blood samples were obtained simultaneously from femoral artery and vein, pulmonary artery and antecubital vein at rest and during isometric and dynamic exercise in six patients during cardiac catheterization and plasma noradrenaline was measured radioenzymatically. 2. Analysis of variance indicated that differences between vascular sites were not significant, whereas differences between patients (P less than 0.001) and differences between activities (P less than 0.001) were significant. 3. Mean systemic arterial concentrations tended to be lower than pulmonary arterial concentrations during each activity, although the difference was not significant. 4. We conclude that forearm venous plasma noradrenaline concentrations are representative of those from other sites.

Factors determining the variability of arterial pressure in hypertension

1. Intra-arterial pressure was recorded continuously in 26 patients with uncomplicated essential hypertension under standardized conditions. Pressure was analysed beat by beat by computer and variability measured as the standard deviation of the normally distributed frequency histogram. 2. Variability was strongly influenced by physical activity, being least during sleep and increasing progressively with bed rest and ambulation. Variability during daytime was not related to time. 3. Systolic variability correlated directly with systolic pressure. An independent inverse relationship with baroreflex sensitivity was observed. Systolic variability tended to increase with obesity. 4. None of the following were related independently with variability: age; race; sex; plasma renin activity; plasma angiotensin II; plasma noradrenaline; plasma adrenaline.

Cold-pressor test

Twenty-one patients with enlargement of the cavernous sinus were studied with CT and MR imaging. Eighteen of the patients also had cerebral angiography. MR was superior to CT in differentiating parasellar aneurysms from neoplastic masses. MR was also superior to both CT and angiography in defining the relationships of cavernous sinus neoplasms to the internal carotid artery, pituitary gland, optic chiasm, infundibulum, and fifth cranial nerves. Only in the definition of bone erosion or hyperostosis was MR inferior to another method (CT). We conclude that MR should be the initial diagnostic study in patients with symptoms of a parasellar mass, with supplementation when necessary by CT and angiography.

Effects of beta-adrenoreceptor antagonists on sino-aortic baroreflex sensitivity and blood pressure in hypertensive man

1. Sensitivity of the sino-aortic baroreflex was investigated before and after acute (23 patients) and chronic (23 patients) beta-adrenoreceptor antagonism in patients with essential hypertension. 2. Sensitivity was inversely related to age (r = -0.60) and systolic blood pressure (r = -0.46); a positive relationship was noted between sensitivity and initial pulse intervals (r = 0.40). 3. Sensitivity increased significantly in patients less than 40 years of age after chronic treatment. No change occurred after acute treatment or in older patients treated chronically. 4. The fall in ambulatory intra-arterial blood pressure after chronic treatment was unrelated to alteration of baroreflex sensitivity.

Changes in plasma norepinephrine, blood pressure and heart rate during physical activity in hypertensive man

We have investigated the changes in plasma norepinephrine and blood pressure and heart rate during a range of physical activities in eight hypertensive subjects in order to determine whether changes in plasma norepinephrine reflect changes in sympathetic activity. Blood pressure was recorded over 24 hours from an intra-arterial cannula. Plasma norepinephrine, measured by a sensitive radioenzymatic method, increased progressively with increasing levels of physical activity. In each subject a statistically significant linear relationship was observed between the logarithm of plasma norepinephrine and systolic blood pressure. Analysis of variance showed that 66% of the variance of plasma norepinephrine was associated with changes in blood pressure and heart rate. These observations support the hypothesis that plasma norepinephrine reflects short-term changes in sympathetic activity. Use of the quantitative relationship described, in conjunction with measurements of norepinephrine metabolism, may help to determine the significance of increased levels of plasma norepinephrine observed in some hypertensive patients.

Influence of once-daily administration of beta-adrenoceptor antagonists on arterial pressure and its variability

Intra-arterial pressure was recorded over 24 h in hypertensive patients before and during long-term treatment with beta-adrenoceptor antagonists given once daily under standardised conditions. Arterial pressure was reduced throughout the 24 h after the last dose as was variability of pressure during physical activity; variability during sleep and rest did not change significantly.

Onset and duration of beta-adrenergic receptor blockade following single oral dose acebutolol hydrochloride (Sectral)

1. The onset and duration of action of once daily acebutolol (400 mg) on resting and exercise heart rate and blood pressure were studied in normal subjects in a double-blind, cross-over trial against placebo. Subjects were studied 1.5, 3, 8 and 24 h after the first dose and 24 h after the fifth dose. 2. Resting and exercise heart rate and blood pressure were significantly reduced within 90 min of the first dose. 3. A significant reduction in these variables persisted throughout 24 h after the fifth daily dose. However, at 24 h the effects were considerably attenuated, the falls in resting and exercise systolic blood pressure being only 5%. 4. A linear relationship was noted between log serum drug level and percentage reduction of exercise heart rate.

Successful treatment of pneumatosis coli with oxygen

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The detection by immunodiffusion of tumour associated antigenic components in extracts of human bronchongenic carcinoma

Antisera to extracts of a variety of bronchogenic carcinoma were raised in rabbits and extensively absorbed with immunoadsorbents prepared with normal lung extracts cyanogen bromide linked to Sepharose 4B, and glutaraldehyde insolubilized normal lung extracts. The antisera were tested by immunodiffusion against a panel of extracts from a variety of bronchogenic carcinoma, foetal lung extracts and pools of normal lung extracts. The results indicate that two distinct antigenic components are associated with bronchogenic carcinoma; one which is present in a high percentage of the tumour extracts tested and appears to have partial identity with a foetal lung component, and one (or more) which is not foetal and appears to have higher cross-reactivity (but not exclusively) with tumours of the same pathological type. Attempts to detect either antibody or antigens relating to these components in the serum of patients with bronchogenic carcinoma by these techniques were unsuccessful. The foetal cross-reacting component was neither carcinoembryonic antigen and alpha1-foetoprotein.

The use of immunoadsorbent columns for the isolation of antibodies specific for antigens associated with human bronchogenic carcinoma

An immunoadsorbent technique is described whereby tumour-specific antibodies may be isolated. Extracts from normal human lung tissue were pooled and bound to cyanogen bromide activated Sepharose 4B. Antisera raised in rabbits to a variety of extracts from human bronchogenic carcinoma were passed through these immunoadsorbent columns to yield antisera specific for tumour-associated antigens as demonstrated by immunodiffusion and immunoelectrophoresis.