Dissociations among the anxiolytic effects of septal, hippocampal, and amygdaloid lesions

Fear reactions of rats given bilateral lesions to the septum, hippocampus, or amygdala were compared with those of rats given sham lesions, in 2 animal models of anxiety: the shock-probe burying test and the elevated plus-maze test. Septal lesions produced anxiolytic effects in both tests (i.e., an increase in open-arm activity and a decrease in burying), whereas hippocampal and amygdaloid lesions produced neither of these effects. On the other hand, hippocampal and amygdaloid lesions impaired rats' passive avoidance of the electrified shock-probe, whereas septal lesions did not. These dissociations suggest that limbic structures such as the septum, amygdala, and hippocampus exert parallel but distinct control over different fear reactions.

Selective recognition of M235T angiotensinogen variants and their determination in human plasma by monoclonal antibody-based immunoanalysis

The common M235T mutation of human angiotensinogen has been shown to be associated with a 10-20% increase in plasma angiotensinOgen level and increased frequency of essential and pregnancy-induced hypertension. The detection of such a common factor in the plasma of individuals at risk could be a useful tool for modern molecular-based medicine. The recognition of M235T variants was investigated using four monoclonal antibodies (mAbs) directed against human angiotensinogen; two immunometric assays were developed. The first assay (using mAbS 7B2 and 4G3) allowed the direct determination of angiotensinogen concentrations and did not show a significant difference with the enzymatic measurement of angiotensinogen. The second assay (using mAbs 1H8 and 1C11) showed a fine distinction between the T235 mutant and M235 wild-type forms of angiotensinogen, with a greater affinity for the latter, as confirmed by biosensor BIAcore experiments. This assay was extremely sensitive in measuring the proportions of the M235 and T235 forms present in the test samples, the first time such a distinction has been achieved in the serpin family. The simple immunoanalysis of the plasma allowed the direct determination of the M235T genotype of the individual tested. Furthermore, it was shown that the T174M mutation, described as being in complete linkage disequilibrium with the M235T mutation, had no influence on these results. Moreover, this assay suggested the presence of the M235 and T235 angiotensinogens in approximately equal amounts in heterozygous plasmas. In conclusion, the immunometric assay described in this study should provide original tools for investigating the relationship between M235T genotype, plasma angiotensinogen levels, and regulation of blood pressure.

Lateral and medial septal lesions reduce anxiety in the plus-maze and probe-burying tests

Previous studies have shown that septal lesions produce anxiolytic-like effects in rat models of "anxiety" (i.e., septal lesions, like anxiolytic drugs, increase rats' open-arm exploration in the elevated plus-maze test and decrease rats' burying behavior in the shock-probe burying test). Although these anxiolytic effects occur after lesions to posterior (but not anterior) regions of the septum, their anatomical specificity has not been clearly defined with respect to classical subdivisions of the septum, such as the medial and lateral nuclei. Thus, in Experiment 1, we compared the effects of lateral or medial septal lesions on rats' anxiety reactions in the elevated plus-maze and shock-probe burying tests. Contrary to the "anxiogenic" effects of septal lesions recently found in a "conflict" model of anxiety, we found that both lateral and medial septal lesions produced equivalent anxiolytic effects in the plus-maze and shock-probe tests. In Experiment 2, we found similar anxiolytic effects whenever lesions included septal areas just anterior to the fornix (i.e., the lateral septum) but not when septal lesions were restricted to areas just posterior to the fornix (i.e., the septofimbrial and triangular septal nuclei). Taken together with our previous results, these data suggest that classical subdivisions of the septum bounded rostrally by the genu of the corpus callosum and caudally by the fornix play an exclusively excitatory role in the control of anxiety, as expressed in the plus-maze and shock-probe burying models.

[Prevalence, treatment and control of hypertension in family practice patients in France during 1994]

The aim of this study was to measure the percentage of patients with hypertension, treated hypertension and controlled hypertension, using data collected over one week by 235 general practitioners well representative of the French medical population and selected by SOFRES Médical. Practitioners had to carry out their own survey over a period of one week on all patients above 18 years of age who visited their office. They were initially instructed to use the same type of mercury sphygmomanometer, equiped with the same pneumatic cuffs of different sizes. Three consecutive blood pressure measurements were effected, the last two were recorded. Patients were considered as hypertensive if the mean of the two recorded BP measurements was > or = 140-90 mmHg, or < 140-90 mmHg under pharmacological treatment. Hypertensive patients were considered as controlled when their blood pressure levels were overall < 140-90 mmHg under treatment. According to age, two other control levels were analysed: blood pressure < 160-95 mmHg before 65 years and blood pressure < 160-90 mmHg at 65 years or more. Among 12,351 patients, 5,020 are hypertensive (4%), 2,985 under pharmacological treatment (59%) and 2,035 without treatment (4%). Among untreated patients, 9% had an hypertension above the borderline values. Before 65 years, 28% had an under treatment blood pressure < 140-90 mmHg and 71% < 160-95 mmHg. Among 65 years or more hypertensive patients, 21% had an under treatment blood pressure < 140-90 mmHg and 60% < 160-90 mmHg. Before 65 years, 25% among patients with a monotherapy remained with a blood pressure > 160-95 mmHg and 34% with a blood pressure > 160-90 mmHg among those of 65 years or more; 230 patients (5%) remained in high risk with a blood pressure > 180-105 mmHg. 176 untreated and 54 despite their treatment. This study carried out in French medical practice yield two main conclusions regarding the management of hypertension: as the prevalence of hypertensive patients is 41%: one patient out of two, high blood pressure has to be a main aim for the medical teaching. Even if a reasonable control of the blood pressure is achieved in most cases, blood pressure got a normal level for 24% only of treated hypertensive patients and too many patients were keeping high risk because they have been not or not enough treated. This study, as a real audit, gives some useful informations to general practitioners in order to improve their scores.

Doppler-derived pulmonary arterial systolic pressure in patients with known systemic arterial pressures

In the present study, we evaluated Doppler-derived systolic pulmonary artery pressure in 476 hypertensive patients. Clinical interpretation of systolic pulmonary arterial pressure should take into account age, body size, and systolic blood pressure values.

Influence of obesity on the diagnostic value of electrocardiographic criteria for detecting left ventricular hypertrophy

Easily applicable, clinically relevant electrocardiographic criteria are needed to screen large populations for left ventricular (LV) hypertrophy. The aim of this study was to evaluate, in a population of 380 hypertensive patients of both sexes, whether obesity modified the diagnostic performance of Sokolow-Lyon and Cornell voltage criteria by comparing them with echocardiographic evaluations using different indexation methods for LV mass presentation (body surface area and various powers of the height variable). For the population as a whole, Cornell voltage was better correlated to LV mass than was Sokolow-Lyon voltage (r = 0.48 and 0.36, respectively). The poorest performance of Sokolow-Lyon voltage was observed among obese patients (best r = 0.1 and 0.21 in obese women and men, respectively). Sensitivities were assessed at a 95% specificity level. In nonobese patients, using sex-adjusted voltage values (43 and 36 mm in men and women, respectively, for Sokolow-Lyon voltage, and 28 and 25 mm for Cornell voltage), the sensitivities of Cornell voltage and Sokolow-Lyon voltage were similar in men and women (near 22% and 36%, respectively), whatever the indexation method used for LV mass. In obese patients, Cornell voltage sensitivity was similar to that of nonobese patients, whereas Sokolow-Lyon voltage had a much poorer sensitivity (<10%). For simple LV hypertrophy detection criteria, Sokolow-Lyon voltage should be avoided in obese hypertensive patients and replaced by the Cornell voltage criteria, which are not influenced by the presence of obesity.

The number needed to treat: a clinically useful nomogram in its proper context

The number needed to treat is a meaningful way of expressing the benefit of an active treatment over a control. It can be used either for summarising the results of a therapeutic trial or for medical decision making about an individual patient, but its use at the bedside has been impeded by the need for time consuming calculations. A nomogram has therefore been devised that will greatly simplify the calculations. Since calculations are now easy, the number needed to treat can be used to access the value of several interventions, although it does have its limitations. In particular it should not be used when it is not known whether the relative risk reduction associated with an intervention is constant for all levels of risk, or for periods of time longer than that studied in the original trials.

Does tolerance develop to the anxiolytic effects of septal lesions?

Previous studies have shown that septal lesions produce anxiolytic-like effects in tests of rat "anxiety" (i.e., septal lesions increase open-arm exploration in the elevated plus-maze test and decrease burying in the shock-probe burying test). The present experiment examined whether "tolerance" develops to the anxiolytic effects of septal lesions, in a manner similar to that of anxiolytic drugs. Accordingly, septal- and sham-lesioned rats were repeatedly tested in the elevated plus-maze. As in previous studies using anxiolytic drugs, septal lesions produced a clear anxiolytic effect on the first test day, but this effect virtually disappeared by the third test day. Although these findings suggest "tolerance" had developed to the anxiolytic effects of septal lesions, these same rats showed clear evidence of anxiolysis when they were subsequently tested in the shock-probe burying paradigm. A second experiment showed that these basic effects did not depend critically on time since surgery. Thus, the diminution of anxiolysis induced by septal lesions in the elevated plus-maze is test-specific and does not reflect a general recovery of normal fear reactions.

Interactive electronic teaching (ISIS): has the future started?

Medical education of hypertensives as well as of other asymptomatic cardiovascular risk patients requires individualized, interactive and attractive strategies. Electronic teaching set up in hospital or clinic settings opens the way of the future, saving time and allowing more advantageous use of caretakers. ISIS (Initiation Sanitaire Informatisee et Scenarisee), a French computer assisted program for cardiovascular risk patients, combines a scientific information, divided in 12 sequential but independent modules, with a recreative imaginary trip in the world of ancient Egypt. To test the impact of this tool on patient health information retention, 158 hypertensives hospitalized in a day-hospital clinic were randomized into an intervention or ISIS group (IG, n = 79) and a control group (CG, n = 79). Both groups received cardiovascular education through standard means. In addition, IG patients underwent a 30 to 60 min session on the computer. Cardiovascular knowledge was tested by a nurse administering a standardized 28-item questionnaire before and two months after education. Retesting was done by telephone interview. A total of 138 completed questionnaires (69 from each group) were analyzed. Overall mean cardiovascular knowledge score before education (14.3 +/- 4.2, range 4-25) improved significantly after education (3.7 +/- 3.5, p = 0.0001). This improvement was more important in the IG than the CG (3.8 +/- 3.6 vs 2.4 +/- 3.2 respectively, p = 0.02), especially in hypertensives having a known disease for more than six months. Isis is now available in two languages: French and English. Patients' satisfaction and the conclusion of this comparative trial encourage confirmation of these first results in other French or English speaking populations, in order to test the long term effects of structured electronic teaching sessions on health behaviour, and to promote a wide use of computers and multimedia communication in hypertension control programs.

Recent advances in pediatric HIV

Pediatric human immunodeficiency virus (HIV) infection is a disease of mother-to-infant transmission. The World Health Organization estimates there will be ten million HIV-infected children by the end of this century. It is now thought that both intrauterine and intrapartum transmission of HIV occurs. Infants infected in utero develop clinical signs and symptoms at an earlier age than those who are infected at the time of delivery. We describe two cases that demonstrate early-onset and late-onset pediatric HIV disease, respectively. Recently, it was determined that perinatal transmission of HIV can be significantly reduced by the administration of the antiretroviral drug, zidovudine (ZDV), to HIV-positive pregnant women and their newborns, making HIV screening of pregnant women more desirable than ever. A program of universal voluntary HIV testing for pregnant women has been successfully implemented at the University of Arkansas for Medical Sciences. Details of this program are described herein.

Benefits of a computer-assisted education program for hypertensive patients compared with standard education tools

ISIS (Initiation Sanitaire Informatisée et Scénarisée), a French computer-assisted hypertension and cardiovascular risk education program, was developed to provide patients at cardiovascular risk with a modern interactive educational tool combining rigorously scientific information with the aesthetic attractiveness of multimedia communication. To test the impact of this tool on patient health information retention, 158 hypertensives hospitalized for initial work-up (day hospital) or therapeutic adjustments (3 days) were randomized into control (n = 79) and ISIS (n = 79) groups. Both groups received cardiovascular education through standard means: physicians, nurses, dietitians and pamphlets. In addition, ISIS patients underwent a 30- to 60-min session on the computer with the ISIS program. Cardiovascular knowledge was tested by the same investigator administering a standardized 28-item questionnaire before and 2 months after education. Retesting was made by telephone. At the time of first assessment, all patients were aware that they would be retested. A total of 138 completed questionnaires (69 from each group) was analyzed. Overall mean cardiovascular knowledge score before education improved significantly after education. This improvement was greater in the ISIS than the control group. These results confirm the potential of computer-assisted education in hypertensives from a specialized center.

Comparison of the oral angiotensin II receptor antagonist UP 269-6 or enalapril 20 mg on blood pressure and neurohormonal effects in salt-deplete man

We compared the response of the oral angiotensin II (Ang II) receptor antagonist (ARA) UP 269-6 with an angiotensin converting enzyme inhibitor (ACEI) enalapril 20 mg or placebo, during salt depletion in normal men. We also evaluated safety and tolerability. Sixteen healthy, normotensive male volunteers followed a standardised salt-depletion regimen for 3 days before each study day. Seven different doses of UP 269-6 (5, 10, 20, 40, 80, 120 and 180 mg) were administered double blind in a four-panel dose escalation, with enalapril and placebo randomised within each panel. Supine and erect blood pressure (BP) and heart rate (HR); serum and urinary electrolytes; plasma active renin (PAR), aldosterone, and Ang II were measured at intervals. Urinary electrolytes and aldosterone were measured for the 24 h before dosing and for 24 h after dosing. Dizziness and light-headedness on standing were reported after UP 269-6 at higher doses. Enalapril caused one episode of symptomatic postural hypotension. No other drug-related adverse events (AE) were noted. There was a dose-related decrease in supine and erect systolic and diastolic BP (SBP, DBP) with UP 269-6 at > or = 40 mg, with no change in HR. Based on the maximal decrease in mean arterial pressure (MAP), UP 269-6 at 180 mg had an effect largely comparable to that of enalapril 20 mg. There was a dose-related increase in PAR with UP 269-6. Although this was greater with UP 269-6 180 mg than with enalapril, serum and 24-h urinary aldosterone suppression was greater with enalapril than with any dose of UP 269-6.(ABSTRACT TRUNCATED AT 250 WORDS)

Which definition for echocardiographic left ventricular hypertrophy?

Left ventricular (LV) hypertrophy is diagnosed on the basis of LV mass measurement at echocardiography. However, various thresholds for defining LV hypertrophy have been published, ranging from 111 to 134 g/m2 and from 100 to 125 g/m2 in men and women, respectively. The aim of our study was to evaluate variations in the prevalence of LV hypertrophy induced by the application of different threshold values among hypertensive subjects. LV mass was calculated in 349 hypertensive patients from an M-mode LV tracing obtained by left parasternal view in 83% and by subcostal view in 17% of patients. The prevalence of LV hypertrophy ranged from 17% to 39%, according to the threshold value applied (from 10% to 47%, and from 19% to 39% in women and men, respectively). As expected, the prevalence of LV hypertrophy in obese patients of both sexes was higher when applying the usual height-indexed threshold (143 and 102 g/m for men and women, respectively) than when applying the usual body surface area-indexed threshold (134 and 110 g/m2 for men and women, respectively). The use of normalized thresholds when comparing different indexation methods (in this case, 145 g/m for men, 120 g/m for women) will minimize these variations in part due to the threshold choice. Considering the clinical and therapeutic implications associated with the presence of LV hypertrophy, better standardization of definitions is needed; this could be based either on better-designed cooperative normality studies or meta-analysis of risk stratification.

Feasibility study of N-of-1 trials with blood pressure self-monitoring in hypertension

The objective of this study was to assess individual responses to antihypertensive treatment by N-of-1 trials using blood pressure self-monitoring in 79 patients of both sexes referred to a hypertension clinic. Thirty-five patients who remained untreated (study 1) and 44 N-of-1 trial participants (study 2) were consecutively selected if their clinic blood pressure was between 160/95 and 220/115 mm Hg and there were no hypertensive complications. Blood pressure was measured daily at home for 21 days (three consecutive measures, morning and evening). Each N-of-1 trial was a single-blind treatment consisting of two successive 10-day treatment pairs, each pair comprising 5 days of placebo followed by 5 days of 20 mg enalapril once daily in the morning. Study 1 showed no significant blood pressure regression toward the mean over 20 days and justified the choice of 5-day treatment periods in study 2. In study 2, blood pressure fell significantly 12 hours after the first administration of enalapril and rose within 24 hours of the end of the 5-day active treatment period. Using evening blood pressure values (12 hours after enalapril intake) from the first treatment pair, 33 patients were classified as responders (diastolic blood pressure fall > or = mm Hg). In 16 of these 33 patients, the fall in blood pressure above 6 mm Hg was not maintained in the morning, 24 hours after drug intake. Response reproducibility was tested by comparison with the second treatment pair: the observed agreement was only 0.71 (chance-corrected agreement: 0.34) when defined according to both evening and morning values.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of a standardized personal medical record by patients with hypertension: a randomized controlled prospective trial

It is widely believed that patients' compliance can be increased by persuading them to participate in their own care. We tested whether patients with hypertension could manage their own clinical records and whether their doing so would affect the quality of their care. Two hundred patients were randomly assigned to an intervention or a control group. Those in the intervention group were asked to complete a 10-page booklet containing a personal standardized medical record. All patients were scheduled for a follow-up appointment at the end of one year and were referred to their general practitioners for interim care. At the end of the follow-up period, the proportion of patients seen was comparable in the two groups. More of the patients in the intervention group than in the control group filled out a questionnaire as requested, and more added comments. Within the intervention group, the proportion of patients seen and the fall in systolic blood pressure were significantly higher among the 44 patients who had completed the personal record as requested than among the 57 who had not. Patients who completed the personal record also had fewer compliance problems.

Renin-secreting tumors

An analysis of the renin-secreting tumors published in the literature suggests the diagnosis of JGC tumor should be evoked systematically in a young patient with severe hypertension and hypokalemia in whom a renovascular lesion has been eliminated by arteriography. A very high PRA usually is observed and blood pressure drops during converting enzyme treatment. Under acute administration of captopril, plasma renin may or may not increase, showing the inconsistency of the secretory autonomy of the tumor. The most useful examination for the localization of the tumor is the CT scan. Excessive renin production may provoke vascular lesions, left ventricular hypertrophy, and impairment of renin function that all disappear after surgical treatment, at the time when blood pressure returns to normal. Primary reninism has great physiologic importance for the hypothesis that favors the essential role of the kidney in determining the level of blood pressure. It can be considered as a unique, purely renin-dependent form of hypertension. This syndrome has no experimental equivalent and is the most caricatural form of other renin-dependent hypertension, such as renovascular disease, and probably some other forms of essential hypertension. The discovery of a renin-secreting tumor therefore constitutes a life-saving diagnosis for the patient, a subject of reflection for the specialist, and a useful tool for studies of the general mechanisms involved in enzyme biosynthesis and tumoral endocrine cell function.

Renal proliferative and phenotypic changes in rats with two-kidney, one-clip Goldblatt hypertension

Angiotensin II (AII) is a vasoconstrictive peptide with hypertrophic and mitogenic effects on many cell types. Previous studies have shown that in vivo administration of AII in rats results in proliferation of, and phenotypic changes in, many renal cell populations, but in doses also causing hypertension. Thus, it was not possible to differentiate nonhemodynamic from hypertensive effects of AII. Therefore, we studied rats with renin-dependent, AII-mediated hypertension (the two-kidney, one-clip Goldblatt model; mean systolic blood pressure 238 +/- 48 v 140 +/- 6 mm Hg in sham-operated controls). The unclipped kidneys, which were exposed to high blood pressure, developed significant glomerular and tubulointerstitial injury, tubulointerstitial cell proliferation, dense focal interstitial monocyte-macrophage influx, increased deposition of types I and IV collagen, as well as increased cellular expression of desmin and actin, in tubulointerstitial areas when examined at 11 weeks. In contrast, clipped kidneys, protected from hypertension but with high local renin expression, had minimal abnormalities. These studies suggest that in this model increased renin, and presumably AII, does not mediate significant proliferative or phenotypic changes in the kidney in the absence of hypertension at 11 weeks.

Accuracy and reproducibility of left ventricular mass measurement by subcostal M-mode echocardiography in hypertensive patients and professional bicyclists

In some patients, left ventricular (LV) mass cannot be evaluated by M-mode echocardiography because the parasternal long-axis view is not available. The aim of this study was to determine whether the subcostal view obtained by M-mode echocardiography under 2-dimensional guidance allows accurate and reproducible LV mass determination. Using the cube formula, LV mass was calculated, from parasternal and subcostal views in 96 subjects: 73 hypertensives and 23 professional bicyclists, covering a wide range of LV dimensions. M-mode tracings were read by 2 experienced echocardiographers and the interobserver variability was evaluated. With use of the subcostal view, the interobserver reproducibility, expressed as observer 1-observer 2, was excellent: -0.3 +/- 1.3 mm for LV diastolic diameter, -0.1 +/- 1.0 mm for ventricular diastolic septal thickness, 0.2 +/- 0.6 mm for diastolic free wall thickness and 0.03 +/- 16.7 g for LV mass. In 96% of cases, the difference in LV mass between the 2 observers did not exceed 30 g. With use of the parasternal and subcostal approaches, LV mass was not statistically different (202.6 +/- 2.2 g and 206.5 +/- 2.0 g, respectively) and the difference was < 52 g (clinically significant threshold) in 91 of 96 cases. It is concluded that, using the cube formula, LV mass calculation based on the subcostal view was accurate and not statistically different from that provided by the usual parasternal approach.

Effects of blocking the angiotensin II receptor, converting enzyme, and renin activity on the renal hemodynamics of normotensive guinea pigs

The effects of three renin-angiotensin system (RAS) antagonists, DuP 753, a nonpeptide angiotensin II (Ang II) receptor antagonist, MK 521, an inhibitor of converting enzyme, and Ro 42-5892, a human renin inhibitor, on renal function and hemodynamics were investigated in anesthetized, ventilated normotensive guinea pigs. This species was selected because this human renin inhibitor inhibits guinea pig renin. Glomerular filtration rate (GFR) and renal blood flow (RBF) were measured by [3H]inulinmethoxy and [14C]aminohippuric acid clearances. Animals were perfused with isotonic saline at 0.2 ml/min. After a stabilization period of 1 h, drugs were given as an intravenous (i.v.) bolus (DuP 753, 1; MK 521, 0.1; Ro 42-5892, 1 mg/kg), followed by continuous infusion (DuP 753, 3; MK 521, 0.3; Ro 42-5892, 3 mg/kg/h). These doses have been used to induce slight but significant and similar decreases in mean arterial blood pressure (MABP). The mean changes during 1-h treatment showed similar decreases in MABP: vehicle, -2 +/- 1% (n = 10); DuP 753, -13 +/- 2% (n = 10); MK 521, -15 +/- 2% (n = 10); Ro 42-5892, -13 +/- 3% (n = 10), p < 0.001. Diuresis was unchanged in the four groups. GFR (vehicle, -0.2 +/- 8.4%; DuP 753, +10.7 +/- 6.4%; MK 521, +13.2 +/- 8.6%; Ro 42-5892, +37.2 +/- 7.5%, p < 0.01) and RBF (vehicle, -0.7 +/- 6.6%; DuP 753, +10.5 +/- 6.8%; MK 521, +16.4 +/- 6.8%; Ro 42-5892, +37.9 +/- 7.8%, p < 0.01) increased in parallel with the three drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Anxiogenic stimuli in the elevated plus-maze

Untreated rats normally avoid the open arms of the "elevated plus-maze," preferring instead the closed arms, whereas rats treated with antianxiety drugs (e.g., diazepam) show far less open-arm avoidance. Although it has often been assumed that rats avoid the open arms because of novelty, height, or open space, the anxiogenic role of these stimuli in the plus-maze has not been systematically examined. In Experiment 1, rats were repeatedly exposed to the elevated plus-maze with the expectation that their "fear" of the open arms would habituate over trials. Instead, open-arm avoidance actually increased on the second trial and showed no evidence of habituating after 18 trials. In Experiment 2, three 30-min sessions of confinement to the open arms ("flooding") failed to decrease rats' open-arm avoidance. Instead, rats that had received flooding avoided the open arms significantly more than control rats during the first test. Experiment 3 showed that although diazepam-treated rats avoided the open arms less than vehicle-controls on the first test this difference dissipated across test trials. Further, diazepam had no carryover effect on rats' subsequent avoidance of the open arms in a nondrugged state. In Experiment 4, plus-maze height was varied from 50 to 6 cm, but rats did not display more open-arm activity as maze height decreased. In Experiment 5, height cues were manipulated by placing a "floor" 8 cm beneath one open arm while leaving the floor of the other open arm at 50 cm. Rats did not avoid the "low" open arm less than the "high" open arm.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical significance of the metabolic effects of antihypertensive drugs

Data from the Hypertension Treatment Trials do not indicate that the metabolic effects of the medications used, namely diuretics in all and beta-blockers in some, are of great clinical significance. Effects on lipids are mainly short-term (about one year) and the increased incidence of significant hyperglycaemia and/or diabetes in treated compared with control or placebo subjects is < 1% in most trials. The use of these drugs has improved the prognosis of subjects with both severe and less severe hypertension. Despite these findings, it is possible that medications such as the calcium blockers, ACE inhibitors, or multiple-action drugs, e.g. the alpha-beta-blockers which have no negative and possibly have some positive effects on lipids and glucose metabolism, will improve outcome still further. We must await additional long-term trials to determine this. It is possible that combinations of small doses of two different agents from different classes of drugs will prove to be the ideal approach to hypertension management in the future: efficacy is improved and any adverse metabolic effects are minimised.