Structure and composition of ferritin cores isolated from human spleen, limpet (Patella vulgata) hemolymph and bacterial (Pseudomonas aeruginosa) cells

Ferritin cores isolated from human spleen, limpet (Patella vulgata) hemolymph and bacterial (Pseudomonas aeruginosa) cells have been investigated by high resolution transmission electron microscopy, electron diffraction and chemical analysis. Hemosiderin particles isolated from thalassemic spleens also have been studied. The results show that there is a marked difference in structure and composition of the biomineral phases. Human ferritin and hemosiderin particles are single domain crystals of hydrated iron (III) oxide (ferrihydrite). Lattice fringes were low in contrast and often discontinuous within the central regions of the core. Heat treatment of human ferritins results in a 5 A shrinkage in particle size and an increase in the single crystalline nature of the core. In contrast, lattice images and electron diffraction of limpet and bacterial cores show no evidence of long-range crystallographic order. Chemical analysis indicates a high inorganic phosphate (Pi) (Fe/Pi = 1.71) content in bacterial ferritin compared with human ferritin (thalassemic) (Fe/Pi = 21.0). The high Pi content of bacterial ferritin suggests a hydrated amorphous iron (III) phosphate mineral core. Structural disorder within the limpet and bacterial cores may be associated with increased Pi content and increased oxidation in Fe(II), resulting in rapid mineral deposition. Growth of the iron (III) oxide cores in human ferritin is discussed on the basis of high resolution electron microscopy results.

The child health clinic: results of a new strategy of community care in a deprived area

Substantial changes were made in the organisation of a child health clinic serving an underprivileged population in Nottingham. A community paediatric team approach was adopted, routine medical checks were reduced, and referrals from elsewhere (including parents) were encouraged. The changes resulted in an older and more deprived population of preschool children being seen by the clinic doctors. More treatable medical disorders were detected with this approach.

Mössbauer spectroscopic studies of the cores of human, limpet and bacterial ferritins

Ferritin cores from human spleen, limpet (Patella vulgata) haemolymph and bacterial (Pseudomonas aeruginosa) cells have been investigated using 57Fe Mössbauer spectroscopy. The Mössbauer spectra were recorded over a range of temperatures from 1.3 to 78 K, all the spectra are quadrupole-split doublets with similar quadrupole splittings and isomer shifts, characteristic of iron(III), while at sufficiently low temperatures the spectra of all the samples show well-resolved magnetic splitting. At intermediate temperatures, the spectra from the human ferritin exhibit typical superparamagnetic behaviour, while those from the bacterial ferritin show behaviour corresponding to a transition from a magnetically ordered to a paramagnetic state. The spectra from the limpet ferritin show a complex combination of the two effects. The results are discussed in terms of the magnetic behaviour of small particles. The data are consistent with magnetic ordering temperatures of about 3 and 30 K for the bacterial and limpet ferritin cores, respectively, while the data indicate that the magnetic ordering temperature for the human ferritin cores must be above 50 K. These differences are interpreted as being related to different densities of iron in the cores and to variations in the composition of the cores. The human ferritin cores are observed to have a mean superparamagnetic blocking temperature of about 40 K, while that of the limpet ferritin cores is about 25 K. This difference is interpreted as being due not only to different mean numbers of iron atoms in the two types of core but also to the higher degree of crystallinity in the cores of the human ferritin.

Chronic treatment with clozapine, unlike haloperidol, does not induce changes in striatal D-2 receptor function in the rat

Comparison has been made of the effects on brain dopamine function of chronic administration of haloperidol or clozapine to rats for up to 12 months. In rats treated for 1-12 months with haloperidol (1.4-1.6 mg/kg/day), purposeless chewing jaw movements emerged. These movements were only observed after 12 months' treatment with clozapine (24-27 mg/kg/day). Apomorphine-induced (0.125-0.25 mg/kg) stereotyped behaviour was inhibited during 12 months treatment with haloperidol. Clozapine treatment was without effect. After 12 months, stereotypy induced by higher doses of apomorphine (0.5-1.0 mg/kg) was enhanced in haloperidol, but not clozapine, treated rats. Bmax for striatal 3H-spiperone binding was elevated throughout 12 months of haloperidol administration, but was not altered by clozapine treatment. Bmax for striatal 3H-NPA binding was only elevated after 12 months of haloperidol treatment; clozapine treatment was without effect. Bmax for 3H-piflutixol binding was not altered by haloperidol treatment, but was increased after 9 and 12 months of clozapine treatment. Dopamine (50 microM)-stimulated adenylate cyclase activity was inhibited after 1 month's haloperidol treatment but normal thereafter. Adenylate cyclase activity was not altered by chronic clozapine treatment. Striatal acetylcholine content was increased after 3 and 12 months of haloperidol or clozapine intake. These findings indicate that the chronic administration of the atypical neuroleptic clozapine does not produce changes in brain dopamine function which mirror those of the typical neuroleptic haloperidol. In particular, chronic administration of clozapine, unlike haloperidol, does not appear to induce striatal D-2 receptor supersensitivity. Unexpectedly, clozapine treatment, unlike haloperidol, altered D-1 receptor function.

Measured and predicted caloric expenditure in the acutely ill

Predicted energy requirements calculated from the Harris-Benedict basal energy expenditure (BEE) formulas, and caloric allowances recommended by the Food and Nutrition Board National Research Council, were compared to metabolic expenditures measured by indirect calorimetry, using a feedback-controlled gas replenishment technique with a prototype device for the continuous determination of oxygen consumption (VO2) and carbon dioxide production (VCO2). In a group of 50 acutely ill surgical patients, predicted metabolic requirements based on ideal body weight (1.75 BEE) averaged 59% greater than metabolic expenditures measured by indirect calorimetry. Metabolic requirements based on actual body weight averaged 52% greater; recommended caloric allowances averaged 39% greater. Thus, accepted methods of predicting metabolic requirements significantly overestimated the caloric needs of these acutely ill patients. These results should encourage the development of new bedside equipment for measuring VO2 and VCO2, so that indirect calorimetry can be used to guide nutritional support in the clinical setting.

Blood pressure variability in health, hypertension and autonomic failure

24h intra-arterial pressure monitoring was used to examine blood pressure variability in 5 normal volunteers, 137 subjects with suspected or established essential hypertension and 9 subjects with autonomic failure. Subjects with autonomic failure showed increased short-term blood pressure variability while active but reduced values at rest. Heart rate variability was low at all times. 24h recordings were reduced to hourly mean values and two indices of variability derived - day-night difference and average hourly change. For blood pressure, subjects with autonomic failure showed negative values of the former but high values of the latter; both indices of heart rate variability were low. In the remaining group, the relationship of these indices to constitutional factors, mean blood pressure and indices of physical activity during the study was explored. Day-night difference in systolic pressure was negatively correlated with mean pressure and average hourly change positively related to age. No other relationship was significant.

Nature of micellar calcium phosphate in cows' milk as studied by high-resolution electron microscopy

The nature of the inorganic calcium phosphate in the casein micelle of cows' milk has been studied by high-resolution electron microscopy. No periodic lattice spacings could be imaged, and diffraction patterns were of the diffuse amorphous type. Short-range order of less than 15 A may be present, but the results indicate that there is no long-range order in micellar calcium phosphate.

Supine hypertension, blood pressure variability and circadian rhythm in autonomic failure: the role of ambulatory intra-arterial monitoring

Blood pressure variation over 24 h was studied in twelve subjects with suspected or established autonomic failure using ambulatory intra-arterial monitoring. Three subjects who had been previously diagnosed as having orthostatic hypotension due to autonomic failure were found to have normal circulatory reflexes. A generally consistent circadian variation of blood pressure was seen in the other nine subjects, pressure rising gradually from its lowest point early in the morning to a peak during the early part of the night; this pattern was also found during bed rest in four subjects. Supine hypertension (an hourly mean blood pressure of greater than 170/90 mmHg) not suspected from sphygmomanometric readings was observed in four subjects, generally during the night. Heart rate variability was reduced in six subjects while short-term blood pressure variability was markedly increased.

The safety of ambulatory intra-arterial pressure monitoring: a clinical audit of 1000 studies

Between 1973 and 1981 1000 successful studies involving ambulatory monitoring of intra-arterial blood pressure were performed using percutaneous cannulation of the brachial artery. We have reviewed the clinical effects of these studies and 35 other cases where attempted cannulation was unsuccessful. One major complication occurred, when an infected haematoma arising at the cannulation site led to the formation of a false aneurysm. In only one other case was distal pulsation diminished following the study. There were 157 reported "minor" complications in 122 studies, including haematoma, haemorrhage, transient paraesthesiae in median nerve territory, and evidence of micro-emboli. A limited study using pulsed wave Doppler ultrasound revealed no significant alteration in arterial lumen size or flow in 20 subjects. The procedure was therefore associated with a much smaller incidence of clinical problems than has been reported with other investigations involving cannulation of the brachial artery.

Differential effects of continuous administration for 1 year of haloperidol or sulpiride on striatal dopamine function in the rat

Administration of haloperidol (1.4-1.6 mg/kg/day) for up to 12 months or sulpiride (102-109 mg/kg/day) for between 6 and 12 months increased the frequency of purposeless chewing jaw movements in rats. N,n-propylnorapomorphine (NPA) (0.25-2.0 mg/kg SC) did not induce hypoactivity in haloperidol-treated rats at any time; sulpiride treatment for 9 and 12 months caused a reduction in the ability of NPA to induce hypoactivity. Haloperidol, but not sulpiride, treatment enduringly inhibited low dose apomorphine effects (0.125 mg/kg SC). After 12 months, stereotypy induced by high doses of apomorphine (0.5-1.0 mg/kg) was exaggerated in haloperidol-, but not sulpiride-treated rats. Bmax for specific striatal 3H-spiperone binding was increased by haloperidol, but not sulpiride, treatment throughout the study. Bmax for 3H-piflutixol binding was not altered by chronic haloperidol or sulpiride treatment. Striatal dopamine-stimulated adenylate cyclase activity was inhibited for the 1st month of haloperidol treatment, thereafter returning to control levels; dopamine stimulation was increased after 12 months of sulpiride treatment. Striatal acetylcholine content was increased after 3 and 12 months of treatment with haloperidol, but was not affected by sulpiride. Chronic administration of sulpiride does not induce identical changes in striatal dopamine function to those caused by haloperidol.

Use of immunologic markers in obscure hematologic disease

Tumor cells from two patients with very different clinical diseases were evaluated using immunologic techniques. The first patient had a persistent T-cell lymphocytosis and other symptoms suggestive of T-cell malignancy. She also had an adnexal mass. Following surgical excision, the mass was identified as a benign teratoma that contained thymic tissue. The T-cell lymphocytosis subsided following removal of the mass. The second patient had leukemia, the cells of which were morphologically identified as myelomonocytic. Surface marker studies, however, showed the presence of monoclonal surface immunoglobulins. Enzymatic digestion of the cells showed that the antibodies were cytophilic and not produced by the tumor population. These studies emphasize the value of immunologic techniques in characterizing tumor cells.

Effect on intra-arterial blood pressure of slow release metoprolol combined with placebo or chlorthalidone

Thirty patients with essential hypertension participated in a double blind crossover trial in which they were randomly allocated to treatment with either once daily slow release metoprolol (200 mg) with placebo or once daily slow release metoprolol (200 mg) with chlorthalidone (25 mg). Ambulatory intra-arterial blood pressure was recorded continuously for 24-48 hours before treatment and two months after each change in regimen. The response of blood pressure and pulse rate to a standard exercise protocol that included supine rest and tilt, isometric, and dynamic bicycle exercise was measured during the same recording periods. Both treatments appreciably reduced blood pressure and pulse rate; mean daytime intra-arterial blood pressure was reduced from 174/95 mm Hg to 158/85 mm Hg by metoprolol plus placebo and to 143/78 mm Hg by metoprolol plus chlorthalidone. This reduction with the combined treatment was significantly greater than with metoprolol and placebo (p systolic = 0.001, p diastolic = 0.004). Mean night time pressures were reduced from 148/78 mm Hg to 139/75 mm Hg by metoprolol plus placebo and to 116/61 mm Hg by metoprolol plus chlorthalidone. Again the reduction in blood pressure was significantly greater with combined treatment (p less than 0.001) than with metoprolol plus placebo. Once daily slow release metoprolol is effective in controlling blood pressure, but this effect is greatly enhanced by the addition of a diuretic.

Effects of estrogen and testosterone on the metabolism of mevalonate by the shunt pathway

Mevalonate is metabolized by a sterol-forming and a non-sterol-forming, also called the "shunt", pathway. Effects of estrogen and testosterone administration on the shunt activity were examined in male and female Wistar and Sprague-Dawley rats. Shunt activity was determined in vivo from the yield of expired 14CO2 following [5-14C]mevalonate injection. Total mevalonate utilized was determined from the yield of expired 14CO2 following [1-14C]mevalonate injection. In the female, about 45% of mevalonate appears to be metabolized via the shunt, and in the male about 20%. This difference between male and female rats is dependent on both testosterone and estrogen, and apparently on testosterone to a greater extent. Thus estrogen treatment produced a 20-35% increase in shunt activity over castrated controls, while castration of males without hormonal treatment resulted in about a 50% increase in shunt activity, and testosterone administration returned castrated male and female shunt activity to that of intact males, or nearly so. Light/dark cycle had no effect in vivo on shunt activity, but may be critical in demonstrating sex differences in shunt activity in kidney slices.

Circadian variation of blood pressure in autonomic failure

We have monitored ambulant intra-arterial blood pressure with the Oxford system in six subjects with autonomic failure who exhibited postural hypotension. Plotting pooled hourly mean values we have demonstrated a consistent circadian trend in blood pressure that was the inverse of the normal pattern, with the highest pressures at night and the lowest in the morning. In four subjects, confinement to bed did not substantially alter this pattern. Heart rate variability was much reduced in four of the subjects, but relatively normal in two in whom blood pressure variation was also less abnormal. There was a correlation of the nadir of the blood pressure measurements with the reported time of peak incidence of orthostatic symptoms. These findings are of importance in both the management and physiologic testing of patients with this condition.

The ultrastructure of the calcium carbonate balance organs of the inner ear: an ultra-high resolution electron microscopy study

The balance organs of the inner ear of vertebrates, found as single, large growths of aragonite ('otoliths') in fish and small clumped masses ('otoconia') of either aragonite (amphibians) or calcite (mammals), have long been regarded as polycrystalline and single crystals respectively. The use of ultra-high resolution electron microscopy and electron diffraction to study comparatively crushed samples of these biominerals and samples of geological calcium carbonates, as examples of pure inorganic crystals, reveals that the biological structures are composed of microcrystals joined together by organic matrices to form composite crystals. Such structures either grow to a finite, controlled size (otoconia) or have daily growth patterns (otoliths). Mechanisms of growth are proposed to link these seemingly different patterns varying only in the number of nucleation sites and the degree of biological as against chemical control over the growth.

Nifedipine or verapamil as sole treatment of hypertension. An intraarterial study

Intraarterial ambulatory blood pressures were recorded prior to and during therapy with two different calcium ion antagonists, nifedipine and verapamil, in two separate groups of patients. In the first group, nine patients were studied off therapy and following a minimum of 6 weeks of nifedipine treatment (dose range, 20 to 60 mg twice daily). A second group of 16 patients followed the identical protocol but were prescribed verapamil (120 to 160 mg, three times daily). During both studies, patients underwent standardized physiological tests including tilt, isometric handgrip, and dynamic bicycle exercise. Both verapamil and nifedipine caused a reduction in blood pressure over most of the 24 hours studied. Nifedipine did not affect heart rate whereas verapamil caused a reduction of approximately 10 bpm. Nifedipine and verapamil did not induce postural hypotension, and the absolute responses to dynamic and isometric exercise were reduced. These results show the efficacy of slow channel inhibitors in the management of essential hypertension.

Safety and efficacy of intravenous quinidine

The safety and efficacy of intravenous quinidine were evaluated in a patient population with a high prevalence of left ventricular dysfunction and intraventricular conduction delays. Quinidine gluconate (mean dose 9.1 +/- 1.6 mg/kg) was administered during electrophysiologic study to 100 patients with ventricular or supraventricular tachyarrhythmias. Clinical heart failure was present in 68 percent of the patients. Left ventricular end-diastolic pressure, cardiac index, and left ventricular ejection fraction were abnormal in 62, 48, and 70 percent, respectively. Major intraventricular conduction delays (QRS of 120 msec or more) were present in 27 percent, and the H-V interval was prolonged (over 55 msec) in 28 percent. Despite the prevalence of these abnormalities, quinidine was discontinued because of hypotension in only 10 patients. Saline solution was infused to maintain preload in 37 percent, and hypotension responded promptly to saline solution infusion or discontinuation of quinidine infusion in all subjects. Hypotension was not more common in patients with more severe left ventricular dysfunction. QRS duration, H-V interval, QTc, and right ventricular effective refractory period increased significantly (p less than 0.001) after quinidine administration. Heart block or QRS widening of 50 percent or more did not occur. Quinidine prevented arrhythmia induction in 26 percent of patients who received full doses. Ventricular tachycardia cycle length increased in all 41 patients in whom identical forms were induced before and after quinidine (287 +/- 71 msec versus 361 +/- 93 msec, p less than 0.001). Intravenous quinidine may be administered safely to patients with intraventricular conduction delays and moderate heart failure. When antiarrhythmic efficacy is assessed by electrophysiologic study, quinidine compares favorably with other antiarrhythmic agents.

Alpha-adrenoreceptor blockade with indoramin in hypertension

We have evaluated the effects of indoramin, an alpha-adrenoreceptor blocking drug, used as sole therapy in a group of 27 patients with essential hypertension. Blood pressure and heart rate were measured continuously over prolonged ambulatory periods using an established invasive technique before and after six weeks of therapy. The protocol was randomised, double-blind, and with double-dummy placebo control. A standardised programme of physiological stress testing was also performed during each study. Placebo produced no appreciable change in the levels or patterns of blood pressure over 24-h periods, but indoramin produced a significant reduction, which was particularly marked during the night. Physiological testing did not reveal any postural hypotension, and the response to dynamic and isometric exercise was modified in level but not in degree of change. There were many unwanted effects, which may limit the clinical value of this drug.

The quantitation of arterial elasticity from Doppler flow measurements

The pattern of phasic pressure and flow in an artery is related to the components of the impedance of that artery and hence to its compliance. Phasic patterns of velocity in peripheral arteries have been recorded by using continuous wave ultrasound Doppler flowmeters coupled to high-speed spectrum analysers; this has enabled display of the stored spectral ensembles as 'sonograms'. Simultaneous recordings at proximal and distal sites in each limb of a variety of subjects were made under standard resting conditions; characteristic patterns of change in the sonogram are recognized where gross abnormalities of arterial anatomy are present. A technique is under development whereby the mean values of velocity for each 7.4 ms time slice are derived, smoothed, and the pulse described by standard Fourier transform analysis. The change of the waveform occurring during passage through the relevant arterial segment is then described by comparing the amplitude/frequency and time-delay/frequency plots at proximal and distal sites. Although results are at present preliminary, changes relating to age and known vascular abnormality are becoming apparent. Further development is in progress to determine the significance of these findings.

The effects of oxprenolol on ambulatory intra-arterial blood pressure in essential hypertension

Continuous intra-arterial blood pressure recording using the "Oxford" technique has been used to study the antihypertensive effects of oxprenolol taken three times daily in fully ambulatory patients with essential hypertension, outside hospital. During the first 24 h of treatment there was a reduction in daytime heart rate and a small reduction in daytime blood pressure. After 10 weeks treatment there was a more substantial fall in daytime blood pressure from the hour of waking, but no effect on sleeping nighttime blood pressure or heart rate. Twenty-four hour variation, as assessed by the amplitude of a fitted regression curve, showed a reduction in heart rate but not blood pressure variation. In 4 patients restudied after 11 weeks treatment with oxprenolol (tid) and cyclopenthiazide at 9 a.m. there was some evidence of an antihypertensive effect occurring during both the daytime and nighttime.

The effect of once daily beta-adrenoceptor blocker-thiazide diuretic combination on the ambulatory blood pressure

1 We have assessed the efficacy of Viskaldix, a combination of pindolol 10 mg and clopamide 5 mg using continuous intra-arterial ambulatory blood pressure monitoring. 2 Fourteen of the sixteen patients entered were studied on no therapy and following a minimum of 6 weeks at a constant dosage of Viskaldix. 3 Viskaldix produced a marked and consistent reduction of the blood pressure over the 24 h. The diurnal variation in the heart rate was decreased. 4 The results were compared with those of a similar study with once-daily pindolol where there was control during the day but not in the early morning when the blood pressures rose rapidly.

Pathways of acetoacetate's formation in liver and kidney

Specifically 14C-labeled palmitic acids were perfused through livers and incubated with slices of kidneys from rats in diabetic ketosis. The distribution of 14C in the hydroxybutyric acid formed was determined. In liver, the ratio of incorporation of 14C from [13-14C]palmitic acid into carbon 1 to carbon 3 of the hydroxybutyric acid was the same as the ratio in carbon 2 to carbon 4 from [6-14C]palmitic acid. In kidney, the carbon 1-to-carbon 3 ratio was more than twice the carbon 2-to-carbon 4 ratio. In both tissues, 14C from [16-14C] palmitic acid was preferentially incorporated into carbon 4 compared to carbon 2 of the hydroxybutyric acid, but more so in liver than kidney. These results mean that in liver, the sole pathway of acetoacetate formation is via hydroxymethylglutaryl-CoA, while in kidney it is not. Rather in kidney, acetoacetyl-CoA is converted to acetoacetate to a large extent by direct deacylation, presumably via a transferase- and/or deacylase-catalyzed reaction. In liver, most of the palmitic acid utilized is converted to acetoacetate while in kidney it is not. We previously estimated that, as a minimum, 11% of the hydroxybutyric acid excreted by the rat in diabetic ketosis is formed without hydroxymethylglutaryl-CoA as an intermediate. The kidney appears to be the source of this hydroxybutyric acid if the pathways operative in these tissues in vitro are those that also operate in vivo.

Once-daily pindolol in hypertension: an ambulatory assessment

Ambulatory monitoring of intra-arterial blood pressure was used to assess patterns of circadian blood pressure in 12 hypertensive patients who were treated with pindolol in either a once- or twice-daily dosage regimen. Neither once-daily nor twice-daily pindolol had much effect during the latter part of the night and early morning. In the six patients who agreed to further crossover studies, the hypotensive effects of once-daily therapy were not significantly different from those produced by a twice-daily regimen. While confirming the effectiveness of once-daily beta blockade in hypertension, we deduce that failure to affect nighttime blood pressure substantially is a feature independent of the dosage regimen and also, probably, of the individual beta blocker used.

Increased striatal acetylcholine after 14 months cis-flupenthixol treatment in rats suggests functional supersensitivity of dopamine receptors

Rats received continuous administration of cis-flupenthixol (0.8-1.2 mg/kg/day) or trans-flupenthixol (0.9-1.2 mg/kg/day) in drinking water for 14 months. The administration of cis-flupenthixol, but not trans-flupenthixol, caused apparent cerebral dopamine receptor supersensitivity. Thus, animals receiving cis-flupenthixol, but not trans-flupenthixol, showed enhanced apo-morphine-induced stereotyped behaviour. Dopamine concentration in striatum was not altered by drug treatment but striatal HVA and DOPAC concentrations were reduced in animals receiving cis-flupenthixol, but not trans-flupenthixol. No consistent change in Bmax of KD for specific striatal 3H-spiperone binding was observed after 14 months drug intake. However, in cis-flupenthixol treated animals a 40% increase in Bmax was observed following 2 weeks drug withdrawal. Continuous cis-flupenthixol intake increased striatal acetylcholine concentrations; trans-flupenthixol was without effect. This suggests the apparent increase in cerebral dopamine receptor supersensitivity caused by continuous long-term cis-flupenthixol administration is of functional importance in the intact animal.

Ankylosing spondylitis and adenocarcinoma of the lung

A man with long standing and severe ankylosing spondylitis, treated with radiotherapy, developed a primary adenocarcinoma of the lung in an area of apical fibrosis. The significance of this is discussed and the literature reviewed.

Intracellular localization of lead in tissues of the mute swan

The aim of this study was to examine the ultrastructure of kidney, liver, blood and intestine of a lead-poisoned bird and compare these with tissues of a healthy bird. From these results it was hoped to reveal that any abnormalities observed were due to lead poisoning and consequently suitable sections were also selected for X-ray analysis. Renal intranuclear inclusions were present in the lead-poisoned swan. X-ray analysis clearly demonstrated that these granules consist of an amorphous mass of lead probably as lead phosphate. Large numbers of electron dense granules were observed in the liver of the lead-poisoned bird and occasionally in the healthy swans liver. X-ray analysis demonstrated that these granules contain iron. Some of the red blood cells of the lead-poisoned swan have opaque granules associated with the plasma membrane, these were not observed in the healthy swan.

The 24-hour ambulatory blood pressure profile with verapamil

The blood pressure response in hypertensive subjects to chronic treatment with verapamil, a calcium antagonist (or, more precisely, a slow-channel inhibitor), was studied using the Oxford system for continuous monitoring of intraarterial blood pressure. Sixteen patients underwent continuous monitoring over a 48-hour period before and after at least 6 weeks of therapy (dose range 120-160 mg three times daily). Each monitoring period included physiologic tests designed to show the effects of different types of exercise. Verapamil produces a consistent reduction of blood pressure over 24 hours, but particularly during the day. Heart rate was similarly reduced. There was no evidence of postural hypotension, and the absolute responses to dynamic and isometric exercise were reduced. The degree of reduction of the blood pressure was consistent, suggesting that slow-channel inhibitors may be appropriate for antihypertensive therapy.

Coital blood pressure in hypertensives. Cephalgia, syncope, and the effects of beta-blockade

During the continuous monitoring of intra-arterial blood pressure in ambulant hypertensive subjects, 18 episodes of coitus were recorded in 11 subjects. Peak values of up to 300/175 mmHg found, the mean for men being 237/138 mmHg and for women 216/127 mmHg. Two patients with coital symptoms (cephalgia and syncope) showed no unusual responses and, when restudied after beta-blockade, one subject showed no reduction in peak coital blood pressure. The results complement those found previously in normal subjects and demonstrate the potential of the technique in investigating coital symptoms.

Does placebo lower blood-pressure?

The effect of placebo on blood-pressure levels in 20 hypertensive patients was examined as part of a double-blind randomised controlled trial with indoramin. Blood-pressure was measured by both standard sphygmomanometry and ambulant intra-arterial monitoring. Blood-pressure reduction during the placebo phase, as measured by sphygmomanometry in the outpatient clinic, was highly significant for both systolic and diastolic pressures. In the same subjects, concomitant assessment by ambulatory monitoring showed no significant effect of placebo on intra-arterial pressure. After indoramin treatment blood-pressures measured in the clinic showed a mean reduction of 6/8 mm Hg whereas intra-arterial monitoring showed mean reductions of 18/13 mm Hg. The placebo response, therefore, appears to be an artifact of clinic blood-pressure measurement and its use as a control value in pharmacological trials may lead to serious underestimation of the efficacy of the active drug.

Can placebo therapy influence arterial blood pressure?

1. With standard sphygmomanometric techniques used in conjunction with continuous intra-arterial monitoring the antihypertensive effect of placebo was examined in a group of patients participating in a controlled clinical trial. 2. Twelve of the 20 patients entered completed all stages of a randomized double-blind controlled trial of placebo and indoramin. Clinic blood pressure in patients receiving placebo showed reductions which were highly significant (P less than 0.001). Simultaneous intra-arterial monitoring showed no reduction of the blood pressure over the 24 h studied. 3. The clinic pressures showed minimal reduction of blood pressure in response to indoramin therapy whereas intra-arterial pressures showed a significant fall (P less than 0.01). 4. The response of the blood pressure to placebo appears to be an artifact of the indirect sphygmomanometric method and its use as a control in this study led to under-estimation of the efficacy of indoramin.

Circadian rhythms in hypertension

Continuous intra-arterial blood pressure recordings have been performed in 37 untreated ambulatory hypertensive subjects, who were investigated on an outpatient basis. Hourly data analysis demonstrated a circadian variation of both blood pressure and heart rate which were highest during the morning and fell during the late afternoon to reach a nadir during sleep. Prior to waking there was an increase in blood pressure, but not heart rate; however both blood pressure and heart rate increased briskly shortly after waking. Chronic therapy with oxprenolol (in 10 patients) reduced daytime blood pressure, but had little effect during the night-time or early morning.

A study of the antihypertensive action of xipamide using ambulatory intra-arterial monitoring

1 The antihypertensive activity of the diuretic xipamide has been studied in 18 patients with mild/moderate essential hypertension using the technique of continuous ambulatory intra-arterial blood pressure recording. Full data from 48 h blood pressure recordings before and after treatment were available from 13 patients. 2 After a mean period of 3 months' treatment with xipamide 20 mg once daily, both systolic and diastolic blood pressure were markedly reduced throughout the whole 24 h day, the reductions of systolic being statistically significant throughout the whole period, and of diastolic for 19 out of the 24 hourly periods measured. There was no postural hypotension seen during treatment and there was a conspicuous lack of side effects. 3 Xipamide would appear to be as effective as many beta-adrenoceptor blockers but without their side effects and produces a better control of blood pressure throughout the whole day and night.

Once daily beta-adrenoceptor blockade in hypertension: an ambulatory assessment

1 The ambulant intra-arterial blood pressure of eighteen hypertensive subjects was monitored before and again after 3 months treatment with thrice daily sotalol (six patients), twice daily pindolol (six patients) and once daily pindolol (six patients). 2 Three patients in the sotalol group underwent a third study having changed to a once daily regimen; similarly six patients in the pindolol groups were restudied having crossed over to the alternative pindolol dosing regimen, total daily dosage being maintained in all cases. 3 Comparison of 24 h blood pressure curves before and after treatment showed effective daytime reduction but less consistent effects at night. 4 In the crossover experiments once daily and multiple daily dosing regimens produced identical patterns of reduction over 24 h in both blood pressure and heart rate. 5 It is inferred that in the treatment of hypertension, once daily dosing with standard preparations of beta-adrenoceptor blocking agents is probable adequate.

Effects of chronic beta-blockade on intra-arterial blood pressure during motor car driving

Continuous intra-arterial blood pressure recordings during motor car driving were performed in 15 patients with untreated essential hypertension, using the "Oxford" recording technique. Each subject was an experienced driver who used his car every day, and for the study drove from his work place to the hospital during the later afternoon. This drive took place in urban traffic and the average duration was 20.9 minutes. Blood pressure during car driving was remarkably stable, and the average systolic and diastolic pressures were similar to the mean daytime pressure. After 16 weeks of treatment with oxprenolol each patient was restudied. Blood pressure during driving had dropped from 176/107 to 160/93 mmHg, but the blood pressure response to driving and blood pressure variation during driving (expressed as the coefficient of variation) were unchanged. After treatment, the mean daytime systolic pressure was lower than the mean pressure during driving, but the relative antihypertensive effect during driving was similar to that observed in the same patients during dynamic exercise on a bicycle ergometer. No drug-induced side effects occurred and there were no apparent effects on driving ability. Chronic treatment with oxprenolol reduced blood pressure during car driving without affecting the normal blood pressure response to driving.

Effects of oxprenolol on the intra-arterial blood pressure response to dynamic exercise in hypertensive men

The intra-arterial blood pressure of 20 male patients with essential hypertension was continuously recorded during dynamic exercise. Graded exercise testing on a bicycle ergometer and a stair-climbing test were performed prior to and during treatment with oxprenolol. Acute oxprenolol therapy was associated with a reduction in heart rate but little reduction in blood pressure. Chronic treatment for 14.3 weeks with oxprenolol (mean daily dose, 344 mg) was associated with a substantial reduction of blood pressure at rest and at each level of bicycle exercise. A similar antihypertensive effect was demonstrated during stair climbing. The normal blood pressure response to exercise as assessed by the relative (percentage) increase in pressure above the pre-exercise level and the rate of increase in blood pressure (per unit of work), as well as exercise tolerance, were unchanged by chronic beta-blockade with oxprenolol.

Ambulant blood pressure: reproducibility and the assessment of interventions

1. We have assessed the day-to-day reproducibility of intra-arterial blood pressure by monitoring 17 freely ambulant hypertensive patients for a period of 48 h. Eight had no change of therapeutic regimen throughout and nine took a single dose of a hypotensive agent before retiring on the second night. 2. Records were analysed to provide hourly mean values of heart rate, systolic and diastolic blood pressure. No significant differences between first and second day recordings were found except after the intervention in the second group. 3. Allowing subjects to follow their normal daily routine produces inevitable variation in their pattern of physical and other activity. However, by the use of these methods of recording and analysis, with pooled measurements from a small group of subjects, reproducibility is sufficiently good to permit the reliable assessment of therapeutic interventions.

Propranolol LA and ambulatory blood pressure

1 The technique of continuous recording of intra-arterial blood pressure in ambulant hypertensives has been used to investigate the effects of a long-acting formulation of propranolol (propranolol LA). 2 Seven subjects with untreated essential hypertension were studied before and 2 months after commencing treatment with propranolol LA once daily in the morning, results showing that smooth control of blood pressure and heart rate occurred throughout 24 h. 3 Bicycle ergometry tests performed by these subjects during both studies showed significant blood pressure reduction by propranolol LA during the mild and moderate grades of dynamic exercise. 4 In a parallel study where six treated hypertensives were monitored before and after substitution of standard propranolol by the 'LA' form, close correspondence of blood pressure throughout the 24 h occurred with each regimen.