On the sex ratio of urinary cation excretion obtained from Intersalt and other epidemiological studies

Large differences exist within populations in the dietary intake of nutrients between men and women and these differences are still largely unknown. Using data obtained from the Intersalt study and from other relevant epidemiological studies, the sex ratio of the 24 h urinary excretion of different cations was obtained. Highly significant correlations (P less than 0.001) were found between the 24 h urinary cation and creatinine excretions of men and women. Highly variable sex ratios of 24 h urinary excretion of cations were obtained between populations, presumably due to the different levels of physical activity between men and women. The sex ratio of blood pressure did not correlate with the sex ratio of the 24 h urinary excretion of sodium, potassium, calcium or magnesium, but correlated significantly with the sex ratio of the BMI (P less than 0.01). On a global scale men had a nearly 22% higher urinary excretion of cations than women, pointing towards a 22% higher dietary intake of the cations considered.

Syringoma--an unusual cause of pruritus vulvae

A case of syringoma of the vulva causing severe vulval pruritus is presented. The patient was thought to have either vulval dystrophy or nonspecific inflammation. Unexpectantly the diagnosis of syringoma was made on pathological examination of biopsy specimens. This unusual case is presented as the presenting symptoms and macroscopic appearance was atypical for syringoma.

Composite mucinous and granulosa-cell tumor of ovary: case report of a unique neoplasm

A 63-year-old woman presented with signs and symptoms of an estrogen-producing ovarian tumor. At laparotomy, this tumor proved to be a multilocular right ovarian mass 20 cm in greatest diameter. The cystic spaces were lined by typical benign mucinous epithelium of the endocervical type, while the greatly thickened cyst walls contained a diffuse proliferation of granulosa cells. These two disparate components were intimately mixed at a variably complex interface to form a composite tumor. While composite tumors showing sex cord-stromal and epithelial elements are well documented, they have all, to date, been of moderately to poorly differentiated androblastomatous or Sertoli-Leydig cell type, associated with heterologous mucinous elements of intestinal differentiation. The combination of granulosa-cell tumor with mucinous elements of endocervical or müllerian type has not hitherto been reported and is of uncertain histogenesis.

Sodium, potassium, body mass, alcohol and blood pressure in three United Kingdom centres (the INTERSALT study)

Standardised data on blood pressure, 24 h urinary electrolyte excretion, body mass index (BMI) and alcohol intake were collected as part of the INTERSALT study in 598 men and women aged 20-59 years, selected randomly from three population groups in the United Kingdom. For the three centres combined, mean systolic blood pressure was 121.4 mm Hg and diastolic pressure 72.1 mm Hg, urinary sodium excretion 152.1 mmol/24 h, urinary potassium excretion 61.0 mmol/24 h, urinary sodium/potassium ratio 2.64 and BMI 25.2 kg/m2. Prevalence of heavy alcohol drinking in men (greater than or equal to 300 ml/week) was 27.5 per cent. Applying overall INTERSALT regression coefficients to the United Kingdom data suggested that modest changes in average sodium and potassium intakes, together with reductions in the prevalence of obesity and (in men) of heavy alcohol drinking could lead to important reductions in average population blood pressures and the prevalence of hypertension. The potential of this multifactorial approach to blood pressure control was illustrated by stratifying individuals within each of the United Kingdom centres by sodium and potassium excretion, BMI and alcohol intake. The 20 (out of 299) men considered at 'lower risk' for high blood pressure with respect to the above variables had systolic pressure lower by 11 mm Hg (P less than 0.01); for the 27 (out of 299) 'lower risk' women, systolic pressure was lower by 5 mm Hg (P = 0.06). These non-pharmacological approaches towards more favourable blood pressure levels could be accompanied by reductions in mortality from stroke and coronary heart disease.

Antagonism of the effects of 5-hydroxytryptamine on the rabbit isolated vagus nerve by BRL 43694 and metoclopramide

Depolarization and reduction in the C fibre compound action potential (C spike) in response to 5-HT were recorded simultaneously from rabbit isolated vagus nerve. 5-HT (0.1-100 mumol/l) was applied cumulatively and EC50 and IC50 values measured from individual concentration-response curves. Blockade of 5-HT responses by the 3-indazole carboxamide, BRL 43694, was investigated and compared with the blocking action of metoclopramide. BRL 43694 was a selective antagonist of 5-HT responses. A concentration of 10 nmol/l BRL 43694, which nearly abolished the depolarization and reduction of the C spike evoked by 5-HT (100 mumol/l), had no effect on similar responses evoked by DMPP (100 mumol/l) or GABA (100 mumol/l). Blockade of 5-HT responses by BRL 43694 (0.3 nmol/l) was slow in onset, a plateau blockade occurring after equilibrium of tissue with antagonist for 2 to 3 h. Metoclopramide induced a blockade of rapid onset. The maximal blockade was apparent within 30 min of application. Full recovery in the responsiveness of the tissue to 5-HT was observed within 30 min of washing out metoclopramide. BRL 43694 at concentrations of 0.3, 1, 3 and 10 nmol/l caused a progressive rightward shift of the concentration-response curves to 5-HT. At the highest concentration of antagonist, there was some depression of the maximal 5-HT response. The apparent pA2 estimated from the Schild equation was 10.03 +/- 0.09 (mean +/- SEM, n = 20) against 5-HT depolarization and 10.31 +/- 0.1 against C spike reduction. Schild plots had slopes not significantly different from 1.0.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of the actions of 5-hydroxytryptamine on the rabbit isolated vagus nerve

Depolarization and reduction in the C fibre compound action potential (C spike) in response to 5-HT were recorded simultaneously from rabbit isolated vagus nerve. 5-HT (0.1-100 mumol/l) was applied either as single concentrations or cumulatively and EC50 and IC50 values measured from individual concentration-response curves. The EC50 values for depolarization (cumulative curves: 2.33, 1.64-3.33 mumol/l, geometric means and 95% confidence limits, n = 31; non-cumulative curves: 3.99, 2.89-5.52 mumol/l, n = 9) were significantly higher than IC50 values for C spike reduction (cumulative curves: 1.25, 0.91-1.74 mumol/l, n = 30; non-cumulative curves: 1.41, 0.72-2.76 mumol/l, n = 8). Complex effects on the C spike were observed, suggesting a susceptible group of C fibres and a 5-HT-resistant component to the C fibre action potential. The motor nerve C fibres in the vagus nerve appear insensitive to 5-HT, whereas the sensory C fibres were sensitive to 5-HT. Phenylbiguanide had a similar selective effect on the C spike, while the depolarizing agents, 1,1-dimethyl-4-phenylpiperazinium (DMPP) and gamma-aminobutyric acid (GABA) did not. Cumulative concentration-response curves for depolarization and C spike reduction could be repeated reproducibly if an interval of 90 min was left between determinations. Up to 6 curves could be generated from one preparation. The 5-HT uptake inhibitor, citalopram (0.1 and 1 mumol/l), had no effect on cumulative concentration-response curves.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the effects of isoflurane and halothane on intraocular pressure

Intraocular pressure (IOP) was measured in four groups of patients receiving isoflurane or halothane in consecutively increasing or decreasing concentrations (1.0, 2.0 and 3.0 MAC in 70% nitrous oxide). IOP decreased significantly in all groups irrespective of whether the higher or the lower concentration of the volatile agent was used first. There were no further significant changes in IOP whether the concentrations were increased or decreased, suggesting no dose-relation. Maximum reductions in IOP were slightly greater in those receiving the higher concentrations of the volatile agents first (64 and 66% with isoflurane and halothane, respectively) in comparison to those receiving the lower concentrations first (54 and 46%, respectively).

Propofol sedation after open heart surgery. A clinical and pharmacokinetic study

One hundred adult patients who required mechanical ventilation after open heart surgery for coronary revascularisation were studied. All received a standard premedication and a high dose opioid anaesthetic. On arrival in the intensive care unit they were allocated randomly to receive either propofol or midazolam to maintain sedation within a predetermined range. Patients who received propofol underwent extubation of the trachea, using standard criteria, after a mean time (log-transformed) of 7.6 minutes after sedation for approximately 17 hours. The corresponding time was 125 minutes in those given midazolam. There were significantly higher morphine requirements during sedation, and higher arterial carbon dioxide tensions 30 minutes after extubation of the trachea, in patients who received midazolam. Pharmacokinetic analysis in 20 patients showed that the elimination half-life of propofol was prolonged (470 minutes) and clearance was reduced (1.14 litres/minute) compared with subjects who had not undergone cardiopulmonary bypass. The rapid clinical recovery was reflected in a rapid redistribution half-life (13.4 minutes), but this was also longer than the redistribution time of 2-4 minutes in other patients.

Body mass index versus height and weight in relation to blood pressure. Findings for the 10,079 persons in the INTERSALT Study

In INTERSALT, an international study of electrolytes and blood pressure, body mass index (kg/m2) was found to relate independently to blood pressure. These relations were assessed in 10,079 men and women aged 20-59 years from 52 centers around the world, based on a standardized protocol, central training of observers, a central laboratory, and extensive quality control. The purpose of the present analyses was to determine whether weight, directly adjusted for height, related to blood pressure as strongly as did body mass index. For all men and women combined, with adjustment for age, sex, alcohol intake, smoking, and sodium and potassium excretion in addition to height, the partial correlations of blood pressure with weight were 0.221 for systolic blood pressure and 0.238 for diastolic blood pressure. These values were slightly larger than the partial correlations for body mass index with blood pressure, which were 0.215 and 0.229, respectively. Although the regression coefficients for body mass index with systolic pressure had been larger in men than in women, suggesting a stronger association of systolic pressure with weight in men, the models with weight directly adjusted for height indicated that the difference in systolic pressure associated with a 10-kg difference in weight was 3.0 mmHg in both men and women. The corresponding weight-associated diastolic pressure differences ranged from 2.00 mmHg in women aged 40-59 years to 2.7 mmHg in men aged 20-39. In addition, with control for weight, height had a significant inverse association with blood pressure. The results of these analyses support the use of weight, with direct adjustment for height, as a useful and practical substitute for body mass index in analyses of the association of adiposity with blood pressure.

Action of antiepileptic and anaesthetic drugs on Na- and Ca-spikes in mammalian non-myelinated axons

The actions of the antiepileptic drugs phenytoin, carbamazepine and phenobarbitone, and the local anaesthetic drugs lignocaine and procaine on sodium-dependent and calcium-dependent compound action potentials (Na- and Ca-spikes) have been compared in rat preganglionic cervical sympathetic nerves, using extracellular recording techniques. There was no discernible difference in the frequency dependence of Na-spike block over the frequency range 0.2-20 Hz between these two groups of drugs. However the antiepileptic drugs were more potent blockers of the Ca-spike, whereas the local anaesthetics were more potent on the Na-spike. It is proposed that a dual action of antiepileptics, a frequency-dependent block of sodium currents combined with a block of calcium currents, may explain their efficacy in the treatment of seizures.

Vulvar adenosquamous carcinoma arising in a hidradenoma papilliferum, with rapidly fatal outcome: case report

A 65-year-old woman with adenosquamous carcinoma of the vulva arising in a hidradenoma papilliferum died from disseminated tumor 2 months after local excision. The light and electron microscopic features of the lesion are presented. The possible origins of vulvar adenosquamous carcinoma are discussed.

INTERSALT study findings. Public health and medical care implications

INTERSALT found a significant association between 24-hour urine sodium excretion and systolic blood pressure in individuals. There was also a significant association between sodium and slope (increase) of blood pressure with age across population samples. The weight of evidence from animal-experimental, clinical, intervention, and epidemiological data favors a causal relation. INTERSALT data from 52 centers in 32 countries permit an estimate of effect on average population blood pressure of lower sodium intake. Based on the sodium-blood pressure association in individuals, it was estimated that a habitual population sodium intake that was lower by 100 mmol/day (e.g., 70 vs. 170 mmol/day) would correspond to an average population systolic pressure that was lower by at least 2.2 mm Hg. This size difference in systolic blood pressure in major US and UK population studies is associated with 4% lower risk of coronary death and 6% lower risk of stroke death in middle age. If habitual diet is both lower in sodium and higher in potassium with lower alcohol intake and less obesity, INTERSALT data estimate average population systolic pressure would be lower by 5 mm Hg. This was calculated to correspond to a 9% lower risk of coronary death and a 14% lower risk of stroke death. INTERSALT cross-population data also suggest that, with a 100 mmol/day lower sodium intake over the life span, the average increase in population systolic pressure from age 25 to 55 years would be less by 9 mm Hg, corresponding at age 55 to a 16% lower risk of subsequent coronary death and 23% lower risk of stroke death.(ABSTRACT TRUNCATED AT 250 WORDS)

The INTERSALT study: results for 24 hour sodium and potassium, by age and sex. INTERSALT Co-operative Research Group

The relations by age and sex of urinary sodium, potassium and sodium/potassium ratio to blood pressure were examined in the 5,045 men and 5,034 women of the INTERSALT Study. With adjustment for age, and combining (pooling) regression coefficients over the 52 centres of the study, sodium excretion was positively and significantly related to the blood pressure of individuals in both men and women. These positive and significant relationships were also found in seven of eight age-sex specific analyses. In most analyses, z-scores suggested stronger associations in women than in men: the size of regression coefficients in women was as much as twice that of the corresponding coefficients in men. In age-specific analyses for men and women combined, sodium excretion was positively related to blood pressure, significantly so for systolic pressure at all ages and for diastolic pressure at ages 50-59; regression coefficients tended to be larger at older compared to younger ages. Results for sodium/potassium ratio in individuals were similar to those for sodium, being stronger in women than in men, and (at least for systolic pressure) at older compared to younger ages. With adjustment for confounding variables, potassium excretion was negatively and significantly related to the blood pressure of individuals; again these relationships tended to be more marked at older ages. Across the centres, median sodium excretion was positively and significantly related to the slope of systolic and diastolic blood pressure with age in men, in both the 52 and 48 centre analyses, and with and without adjustment for confounding variables.(ABSTRACT TRUNCATED AT 250 WORDS)

The INTERSALT study: an addition to the evidence on salt and blood pressure, and some implications

The balance of evidence from animal studies, clinical observations, human experimental studies, and epidemiological studies favours a causal association between sodium and blood pressure. INTERSALT is the largest and most comprehensive study yet published on the sodium-blood pressure relationship, and its significant findings in individuals gives further support to a judgment of causality, although it is likely that the size of the relationship is underestimated. Trials of sodium restriction in individuals have generally shown an effect on blood pressure similar to that predicted from population studies. The effect seems to be more marked at older ages, at higher blood pressures and with more severe sodium restriction. In treated hypertensive patients, sodium restriction (either alone or in combination with weight loss and moderation of alcohol intake) can reduce the amount of medication required to control blood pressure, and in some cases blood pressure may be controlled by dietary measures alone, particularly in those whose hypertension is 'mild' (i.e., uncomplicated and with less marked elevations of pressure). The Portuguese salt trial showed that intervention at the community level can be successful in lowering both sodium intake and blood pressure, although this was not achieved in a community trial in Belgium. In the light of the evidence on sodium and blood pressure, recommendations on sodium intake are made with respect both to the individual, and to the population as a whole.

The INTERSALT study: relations of body mass index to blood pressure. INTERSALT Co-operative Research Group

In INTERSALT, the relationship between body mass index (kg/m2) and blood pressure was studied in 10,079 men and women aged 20-59, sampled from 52 centres around the world, based on a standardised protocol with central training of observers, a central laboratory and extensive quality control. Body mass index-blood pressure relationships were first studied in men and women within each centre, and results of these regression analyses were then pooled for all 52 centres. With adjustment for age, alcohol intake, smoking, and sodium and potassium excretion, body mass index was positively associated with systolic blood pressure among men in 51 of 52 centres and among women in 47, significantly so in 24 and 27, respectively. Body mass index was positively associated with diastolic blood pressure in 51 and 49 centres in men and women, respectively, significantly so in 33 and 31. When the within centre regression coefficients were pooled, the pooled coefficients were highly significant in all analyses (P less than 0.001), and were similar for those aged 20-39 and 40-59. Overall, a 10 kg difference in body weight was associated on average with a 3.0 mmHg difference in systolic and a 2.2 mmHg difference in diastolic pressure. In further analyses across centres, median body mass index was related significantly to median systolic blood pressure, median diastolic pressure and the prevalence of hypertension in both men and women. Body mass index was related to the slopes of systolic and diastolic blood pressure with age in women, but not in men. These INTERSALT findings confirm the importance of the association between body weight and blood pressure. Differences of 2-3 mmHg in systolic blood pressure on a population basis have been shown to be associated with differences in stroke mortality rates of 6-9 per cent and in coronary death rates of 4-6 per cent.

Blood pressure in four remote populations in the INTERSALT Study

Four remote population samples (Yanomamo and Xingu Indians of Brazil and rural populations in Kenya and Papua New Guinea) had the lowest average blood pressures among all 52 populations studied in INTERSALT, an international cooperative investigation of electrolytes and blood pressure. Average systolic blood pressure was 103 versus 120 mm Hg in the remaining INTERSALT centers; diastolic blood pressure in these four population samples averaged 63 versus 74 mm Hg in the 48 other centers. There was little or no upward slope of blood pressure with age; hypertension was present in only 5% of the rural Kenyan sample and virtually absent in the other three centers. Also in marked contrast with the rest of the centers was level of daily salt intake, as estimated by 24-hour urinary sodium excretion. Median salt intake ranged from under 1 g to 3 g daily versus more than 9 g in the rest of INTERSALT populations. Average body weight was also low in these four centers, with no or low average alcohol intake, again unlike the other centers. The association within these four centers between the above variables and blood pressure was low, possibly reflecting their limited variability. While several other INTERSALT centers also had low average body weight or low prevalence of alcohol drinking, when this was accompanied by much higher salt intake (7-12 g salt or 120-210 mmol sodium daily), hypertension prevalence ranged from 8% to 19%. These findings confirm previous reports that in populations with a low salt intake, there is little or no hypertension or rise of blood pressure with age.(ABSTRACT TRUNCATED AT 250 WORDS)

Onset and duration of clinical relaxation of atracurium and vecuronium in patients on chronic nifedipine therapy

The onset and duration of clinical relaxation of atracurium and vecuronium were studied in patients on chronic nifedipine therapy and compared to similar groups of patients not on such a therapy. Neuromuscular block was monitored by recording the integrated electromyogram of the hypothenar muscles (using a 'Datex Relaxograph') following stimulation of the ulnar nerve with a train-of-four stimulation. Neither the time to onset of maximum block (3.0-3.4 min) nor the duration of clinical relaxation (36-40 min) differed significantly between the groups indicating no significant interaction in humans between atracurium and vecuronium and chronic nifedipine therapy.

A comparative study of proliferating (borderline) and invasive epithelial ovarian tumours in young women

A series of 18 patients with proliferating or borderline ovarian tumours and 18 with invasive ovarian tumours is discussed. Proliferating tumours occurred at a younger mean age than invasive disease, and presented at an earlier stage, both contributing factors to their more favourable outlook. Histopathological assessment revealed that the majority of both proliferating and invasive tumours were of serous origin. Mucinous cell type occurred less often as did the endometrioid and clear cell types. The management of the proliferating tumours involved 'radical' surgical procedures in 11 of 18 (61.6%) patients. Only 7 patients (38.8%) had conservative surgical procedures performed. Six patients (33%) had adjuvant chemotherapy while 2 (11%) also underwent abdominopelvic irradiation. All patients with invasive disease had radical surgery and adjuvant chemotherapy and 2 also received abdominopelvic irradiation. The fact that epithelial malignancies of the ovary do occur in younger women needs to be remembered by gynaecologists contemplating surgical procedures on younger patients with adnexal masses. Proliferating or borderline tumours tend to occur more frequently in the younger age groups, and contrary to the implication of their name, they are associated with significant morbidity and mortality.

Extraovarian peritoneal serous papillary carcinoma. A clinicopathologic study of 31 cases

The rate and clinical features of patients admitted to King George V Hospital with extraovarian peritoneal serous papillary carcinoma during a 9-year period were reviewed. In this time, 31 of 236 (13%) patients with an initial diagnosis of invasive serous ovarian carcinoma fulfilled the surgicopathologic criteria for this entity. All patients had disseminated tumor equivalent to ovarian Stage III and IV disease (International Federation of Gynecology and Obstetrics [FIGO]) and with predominantly high-grade neoplasms. They were managed by surgical exploration, tumor debulking where possible, and postoperative chemotherapy. A comparison with a contemporaneous series of 139 patients with primary epithelial ovarian carcinoma matched for stage and grade of disease and managed similarly showed no difference in actuarial survival. The median survival times were 11.3 months for patients with extraovarian serous papillary carcinomas and 13.5 months for patients with equivalent primary ovarian neoplasms. The features of the disease and the treatment regimens used are discussed.

A pilot study of sexual lifestyle in a random sample of the population of Great Britain

Rates of sexual-partner change and patterns of high-risk behaviour are important determinants of the spread of HIV. We carried out a survey to assess the feasibility of studying sexual lifestyle in a random sample of the British population, aged 16-64 years, in November 1987. Two thousand and seventy-seven households were selected using a multi-stage probability sampling procedure. Seven hundred and eight-five adults participated in a structured interview. The schedule included demographic details, attitudes to AIDS, numbers of sexual partners in different time periods, history of homosexuality and contact with prostitutes. An interview was obtained in 61% of households where contact was made, but the overall response rate was low (48%). There was marked variability between individuals in numbers of sexual partners in given time intervals. Men and women in younger cohorts had experienced first sexual intercourse earlier and had higher numbers of sexual partners than people in older cohorts. Surprisingly few reported high-risk behaviour such as homosexuality and use of prostitution. The methodological problems in trying to obtain unbiased and valid data on sexual behaviour are discussed. Further work is necessary to improve the response rate and questionnaire design.

The INTERSALT study: main results, conclusions and some implications

INTERSALT is an epidemiological study of electrolyte excretion and blood pressure in 10,079 men and women from 52 centres and 32 countries. The data were collected according to strict protocol with extensive quality control, and were analysed both in individuals and across centres. In the individual analysis, with adjustment for confounding variables, significant positive associations were observed between blood pressure and twenty-four hour sodium excretion, body mass index and alcohol intake, and significant negative associations between blood pressure and potassium excretion. For a number of reasons, it is likely that the size of these relationships was underestimated. Across centres, linear slope of blood pressure with age was positively related to median sodium excretion. These observations imply that a policy combining changes in sodium and potassium intake with reductions in obesity and alcohol consumption could bring important public health benefits.

Public health measures for blood pressure control in the whole community

One approach to the prevention of blood pressure-associated cardiovascular disease is to find increased numbers of "hypertensives" and bring them under treatment. A complementary approach is to attempt to change the blood pressure distribution of the whole population. It can be calculated that, if the association between blood pressure level and mortality were reversible, a reduction of diastolic blood pressure of 5 mmHg in the population mean would be associated with a substantial reduction in cardiovascular mortality. The assumption of reversibility of risk of coronary heart disease may be more reasonable in the long than in the short term. The evidence from INTERSALT and other studies suggests that readily achievable changes in sodium and potassium intake, in body mass index and in alcohol intake, could lead to average blood pressure change across a whole population of 5 mmHg. A major task for public health is the implementation of such life-style changes among different social class and ethnic groups.

Inhibition of Ca-spikes in rat preganglionic cervical sympathetic nerves by sympathomimetic amines

1. Propagated Ca-spikes were recorded from isolated cervical sympathetic nerve trunks of the rat when bathed in a solution containing 5 mM Ca2+, 0.5 or 1 microM tetrodotoxin (to block Na currents) and 1 mM 4-aminopyridine (to reduce K currents). 2. Spikes persisted when external Ca2+ was replaced with Sr2+ or Ba2+, but were blocked by the addition of the following inorganic Ca-channel blockers (in descending order of potency): Cd2+ greater than La3+ greater than Ni2+ greater than Co2+ greater than Mn2+ greater than Mg2+. 3. Ca-spike amplitude was reduced by up to 90% by (-)-noradrenaline (IC50 1.5 microM). The following sympathomimetic amines imitated this effect (in descending order of potency): clonidine greater than or equal to (-)-adrenaline greater than or equal to [(-)-noradrenaline] greater than or equal to dopamine greater than (-)-phenylephrine greater than or equal to (+/-)-amidephrine. 4. Ca-spike inhibition by (-)-noradrenaline was antagonized by phentolamine (pA2 6.5). Yohimbine was about 10 times weaker than phentolamine; (+/-)-propranolol (1 microM) and prazosin (10 microM) had no clear effect. 5. (-)-Noradrenaline reduced the amplitude of the compound action potential recorded from the superior cervical sympathetic ganglion following supramaximal preganglionic trunk stimulation when recorded in normal Krebs solution and hyperpolarized the ganglion with respect to the post-ganglionic trunk. Depression of the transmitted ganglionic action potential was antagonized by phentolamine (5 microM) but not by yohimbine (1 microM); in contrast 1 microM yohimbine completely prevented the ganglionic hyperpolarization. (-)-Noradrenaline did not hyperpolarize the preganglionic cervical sympathetic nerve trunk under these recording conditions. 6. It is suggested that inhibition of transmitter release from sympathetic preganglionic fibres produced by noradrenaline results from a depression of the voltage-gated Ca current in the fibres and/or their terminals, and that this action is mediated by an alpha-adrenoceptor which does not fully conform to either alpha 1 or alpha 2 subtypes.

The depolarizing action of 5-hydroxytryptamine on rabbit isolated preganglionic cervical sympathetic nerves

This study describes a depolarizing action of 5-hydroxytryptamine (5-HT) on rabbit isolated preganglionic cervical sympathetic nerves using an extracellular recording technique. From cumulative concentration-response curves for 5-HT (1 mumol/l-1 mmol/l), the mean maximal depolarization was shown to be 277 +/- 32 microV and EC50 was 9.4 mumol/l (6.5-13.6 mumol/l, geometric mean, 95% confidence limits, n = 42). The responses to 5-HT displayed marked tachyphylaxis. When cumulative concentration-response curves to 5-HT and 2-methyl-5-HT were determined in the same preparations (n = 4), the mean maximal response to 5-HT was 519 +/- 167 microV, EC50 32.2 mumol/l (8.8-118 mumol/l) and the mean maximal response to 2-methyl-5-HT was 317 +/- 63 microV, EC50 35.1 mumol/l (12.9-95.5 mumol/l, geometric means, 95% confidence limits). The action of selective 5-HT antagonists was tested on repeated cumulative concentration-response curves to 5-HT. Neither methiothepin (0.1-1 mumol/l, n = 3) nor ketanserin (0.1-1 mumol/l, n = 3) had an action on 5-HT responses. The selective 5-HT3 antagonists MDL 72222, ICS 205-930 and SDZ 206-830 were all potent antagonists of the 5-HT depolarizations. The action of these antagonists was quantified by determining the apparent pA2 from the dose ratios and a Schild plot.(ABSTRACT TRUNCATED AT 250 WORDS)

Reproductive performance in C57BL and I strain mice

Mice of the I strain are regarded as difficult to breed. To characterize and elucidate the cause of poor reproductive performance in I strain mice, records of reproductive performance were analyzed from Cancer Research Laboratory, Kirschbaum Memorial Laboratory and Strong Research Laboratories which had bred the I strain mice and a control strain, C57BL, and compared with data from Jackson Laboratory and from three dietary studies conducted in this laboratory. Reproductive performance in the I strain mice is characterized by fewer productive matings, fewer litters and smaller litters than C57BL mice. Also, fewer mice of the I strain survive to weaning. These factors result in the production of only half as many mice per dam in the I strain as the C57BL mice. The fewer number of litters is not due to a greater proportion of resorptions in the I mice, nor are there differences in the survival of either sex. Diets which contain slightly higher (8-12 mg per kg of diet) amounts of pyridoxine (PN) than recommended (1-6 mg per kg of diet) improve performance in the I strain. However, 410 or 1230 mg PN does not increase productivity further. That survival rate of the C57BL mice improves with higher amounts of PN (410 and 1230 mg diets), suggests another dietary factor may be limiting for I strain mice. The reproductive performance in I strain mice is better with diets which result in a higher body weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Synthesis and immunological evaluation of N-terminal, noncrossreactive tachykinin antigens

The N-terminal hexa- or pentapeptide sequences of the three mammalian tachykinins substance P, neurokinin A, and neurokinin B have been synthesized by the conventional solid-phase procedure with 6-aminocaproyl-S-(acetamidomethyl)cysteine as a C-terminal spacer and attachment function. A fourth sequence, with an additional N-terminal 6-aminocaproyl residue on the substance P-hapten sequence, was cyclized N- to C-terminally. For this purpose, a four-level protection scheme has been applied: BOC-TFA for N-terminal protection and cleavage; TFA-stable but HF-labile anchoring function and side-chain protection; S-acetamidomethyl for semipermanent thiol protection. The side chain amino function of Lys was protected with NO2Z, stable against HF but readily cleaved with hydrogenation. The hapten sequences were coupled to maleimidated BSA, after the Acm group was removed by mercury/hydrogen sulfide treatment. Mice immunized with the three linear hapten sequences produced sera that were specific in enzyme-linked immunosorbant assay for the presented hapten and the respective tachykinin but displayed no crossreactivity at all toward the other haptens nor to one of the other tachykinins. It is concluded that this approach produced antisera, specific and selective for its respective mammalian tachykinins.

Sodium and blood pressure: positive associations in a north London population with consideration of the methodological problems of within-population surveys

Blood pressure (BP) and 24-hr urinary sodium (Na) and potassium (K) excretion were measured in 58 men and women aged 40 and above who were selected randomly from the age-sex register of a general practice in North London. All 58 urine collections were reported as complete, but only 28/56 (50%) were classified as 'complete' by the excretion of a biological marker, p-aminobenzoic acid (PABA). Reliability of Na excretion estimated from repeated urine collections was 0.86, indicating that variability of Na excretion within individuals in this middle-aged and elderly population was low. Systolic blood pressure (SBP) was significantly related to 24-hr Na excretion and to 24-hr Na/creatinine ratio. After adjustment for age, sex and body mass index, a SBP-Na regression coefficient of 0.091 mmHg/mmol Na (P = 0.02) was observed. On simple regression analysis, a significant association was also found between diastolic blood pressure and Na (P = 0.04). In the sub-group classified as 'complete' collectors by PABA excretion, BP-Na regression coefficients were larger than in analyses of the sample as a whole. BP was not significantly related to K or Na/K.

Intra-ocular pressure changes during induction of anaesthesia and tracheal intubation. A comparison of thiopentone and propofol followed by vecuronium

Intra-ocular pressure was measured during induction of anaesthesia with propofol (n = 40) or thiopentone (n = 40) followed by vecuronium to facilitate tracheal intubation which was carried out 3 minutes after the administration of relaxant. The average induction doses were 2.15 and 4.83 mg/kg for propofol and thiopentone, respectively. Half the patients in each group received a supplementary dose of the same induction agent (propofol 1.0 mg/kg or thiopentone 2.0 mg/kg) (corrected) prior to intubation. Both propofol and thiopentone produced a significant reduction in intra-ocular pressure which decreased further after administration of vecuronium as well as the second smaller dose of the induction agents. Intra-ocular pressure prior to intubation was lower in the two propofol groups in comparison to the corresponding thiopentone groups. Intubation was associated with an increase in intra-ocular pressure but it still remained significantly below the baseline values except in the group given one dose of thiopentone. Supplementary doses of induction agents before intubation attenuated the increase in intra-ocular pressure. Propofol was significantly more effective in this respect and this group showed the lowest intra-ocular pressure throughout the study period. However, administration of propofol resulted in a 30% incidence of pain on injection and a decrease in systolic arterial pressure of more than 30% in about half the patients.

Intraocular pressure changes during rapid sequence induction of anaesthesia: comparison of propofol and thiopentone in combination with vecuronium

Intraocular pressure (IOP) was measured during rapid sequence induction of anaesthesia using thiopentone or propofol as the induction agent and vecuronium for neuromuscular blockade. Vecuronium was administered in a dose of 0.15 mg kg-1 approximately 35 s before the induction agent. IOP was measured with a handheld applanation tonometer before anaesthesia, following administration of the induction agent, immediately after tracheal intubation and cuff inflation and 1, 2 and 3 min later. IOP in the propofol group was significantly lower than in the thiopentone group, except immediately after induction, when reduction in IOP was similar and significant with both agents. IOP following intubation in patients in whom anaesthesia was induced with thiopentone was not significantly different from baseline values, but showed a significant increase from the pressure before intubation. In contrast, IOP after intubation in the propofol group remained not only significantly less than the baseline value, but also showed only a minimal and insignificant change in comparison with values before intubation. The frequency of side effects was low in both groups except for a significantly greater reduction in arterial pressure in those receiving propofol.

The effects of vecuronium on intra-ocular pressure

The effects of vecuronium on intra-ocular pressure were investigated in doses of 0.1 mg/kg during steady state anaesthesia (n = 5), 0.1 mg/kg as part of a normal sequence induction preceded by thiopentone (n = 10), and 0.15 mg/kg as part of a rapid sequence induction with vecuronium administered prior to thiopentone (n = 10). Administration of vecuronium during steady state anaesthesia was associated with a significant decrease. Vecuronium produced a small reduction in pressure during a normal sequence induction, following a significant reduction after thiopentone. Tracheal intubation during normal sequence and rapid sequence inductions produced increases in pressure above the pre-intubation value (significantly so in the case of normal sequence induction); however, the intra-ocular pressure always remained below the pre-induction value, which suggests that vecuronium 0.15 mg/kg is a suitable relaxant as part of a rapid sequence induction technique where the use of suxamethonium is contraindicated.

Diet, alcohol, body mass, and social factors in relation to blood pressure: the Caerphilly Heart Study

Data for 387 men who had completed seven-day weighed dietary records as part of the Caerphilly Heart Study were examined for relations of alcohol, diet, body mass index (BMI), and other variables to blood pressure. These included age, smoking, exercise, and social class. For men not on antihypertensive treatment (n = 356) regression analysis showed that age (p less than 0.001), BMI (p less than 0.05), and alcohol intake (p less than 0.01) were significantly related to systolic blood pressure, and BMI (p less than 0.001) and alcohol intake (p less than 0.01) to diastolic blood pressure. In addition, protein intake (p less than 0.05) was significantly and inversely related to the risk of being hypertensive, but other dietary variables were not related to blood pressure. For men on antihypertensive treatment (n = 31) significant inverse correlations were observed between diastolic blood pressure and the intakes of potassium (p less than 0.01), fibre (p less than 0.001), polyunsaturated fat (p less than 0.01), and a number of other dietary variables. Reasons for these differences are discussed.

Hepatitis B vaccine: immunogenicity and follow-up including two year booster doses in high-risk health care personnel in a London teaching hospital

One hundred forty-four adult health care personnel (aged 18-62 years, median 33 years) considered at high risk of future HBV infection were vaccinated with a plasma-derived hepatitis B vaccine (20 micrograms HBVax at 0, 1, and 6 months) and followed-up for 2 years. Anti-HBs was present in only 6.9% prior to vaccination, and prescreening to detect this group would not have been cost-effective. At 9 months, 8.3% were nonresponders and a further 9% had anti-HBs levels less than 50 mIU/ml. Multivariate analysis showed that age was the single most important determinant of a poor response. In 47 of 52 individuals retested 2 years later, anti-HBs levels had fallen by 80% or more, and in four it had become undetectable. Response to a booster dose at this stage was excellent, with anti-HBs levels 3 months later much higher than at the end of the initial course. Additional booster doses of vaccine in two of the initial nonresponders at 14 and 22 months, respectively, also led to seroconversion. Although a significant proportion of health care workers in this study did not make a satisfactory response to the hepatitis B vaccine, later booster doses were very effective in subsequently increasing anti-HBs levels.

Enzyme Immunoassay for Detection of Salmonella in Foods: Collaborative Study

A collaborative study was performed in 25 laboratories to validate an enzyme immunoassay (EIA) procedure utilizing 2 specific monoclonal antibodies for rapid detection of Salmonella in foods. The EIA was compared with the standard culture procedure for detection of Salmonella in 6 food types: ground black pepper, soy isolate, dried whole eggs, milk chocolate, nonfat dry milk, and raw deboned turkey, Uninoculated and inoculated samples were included in each food group analyzed, with the exception of poultry which was naturally contaminated. There was no significant difference in the productivity of the EIA and culture procedures at the 5% level for any of the 6 foods. The enzyme immunoassay screening method has been adopted official first action.

Hydrophobic Grid Membrane Filter Method for Aerobic Plate Count in Foods: Collaborative Study

Twenty-one laboratories participated in a collaborative study to validate a hydrophobic grid membrane filter (HGMF) method for aerobic plate count by comparing its performance against the AOAC/APHA pour plate method. Raw milk, raw poultry, whole egg powder, flours, and spices were included in the study. Counts obtained by the HGMF and pour plate methods did not differ significantly, except in the case of whole egg powder, for which the HGMF method produced significantly higher counts. The hydrophobic grid membrane filter method for aerobic plate count in foods has been adopted official first action.

Effect of pretreatment with ranitidine on the hypnotic action of single doses of midazolam, temazepam and zopiclone. A clinical study

Patients receiving midazolam, temazepam or zopiclone by mouth as premedication for minor gynaecological surgery were pretreated with either ranitidine or an inert tablet. Pretreatment with ranitidine was associated with a greater degree of drowsiness at 20 and 40 min after midazolam, and a shorter mean time to peak hypnotic effect than in the non-pretreated group. Ranitidine did not affect the degree of drowsiness in the patients receiving temazepam or zopiclone.

Age and nature of operation influence the pharmacokinetics of midazolam

The pharmacokinetics of midazolam were studied in surgical patients given 0.3 mg kg-1 i.v. for either the induction of anaesthesia, or postoperative sedation following cardiopulmonary bypass. The short elimination half-life of midazolam (2.4 h in patients less than 50 yr undergoing minor surgery) was significantly, although not markedly, prolonged with age (4.1 h in patients greater than 50 yr undergoing minor procedures) and by the nature of the operation (3.8 h after major operative procedures). These changes were the result of alterations in clearance and volume of distribution with age, and in volume of distribution with nature of operation.

The influence of H2 receptor antagonists on the plasma concentrations of midazolam and temazepam

This study shows that 1 day's treatment with cimetidine or ranitidine causes a raised relative systemic availability of orally administered midazolam (p less than 0.01), but pretreatment with a common emulsion antacid does not alter bioavailability. Temazepam bioavailability after oral administration is unchanged after either H2 receptor antagonist, or after the emulsion antacid. The difference in the systemic availability of the two benzodiazepines following pretreatment with either cimetidine or ranitidine may be explained by inhibition of the mixed function oxidase system in the liver. Drugs with a relatively high liver extraction ratio, such as midazolam, are likely to be affected to a greater extent than those with a low extraction ratio, such as temazepam. The clinical relevance of these findings is yet to be determined.