Altered activity of midbrain dopamine neurons following 7-day withdrawal from chronic cocaine abuse is normalized by D2 receptor stimulation during the early withdrawal phase

Using in vivo single-unit recording in rats, we compared the effects of continuous cocaine infusion via minipump or single daily injections (both 40 mg/kg/d x 14 days, S.C.) on the activity of putative dopamine (DA) neurons in the substantia nigra pars compacta (SNC) and ventral tegmental area (VTA). On days 1-5 after cocaine withdrawal, animals were further treated with single daily injections of DA agonists. On withdrawal day 7 continuous cocaine caused a reduction in spontaneously active neurons in the SNC and reduced bursting in the VTA. In contrast, intermittent cocaine resulted in an increase in the number of active neurons in the VTA. These changes were all reversed by apomorphine or quinpirole given during the first 5 withdrawal days. The D1 antagonist SCH 39166 did not antagonize the effects of apomorphine in either region. The role of D2 receptors in modulating baseline DA activity during intermediate cocaine withdrawal is discussed.

Sulfation of chondroitin sulfate in human articular cartilage. The effect of age, topographical position, and zone of cartilage on tissue composition

The chondroitin ABC lyase digestion products of normal human femoral condyle articular cartilage and of purified aggrecan were analyzed for their mono- and nonsulfated disaccharide composition. Changes in the total tissue chemistry were most pronounced during the period from birth to 20 years of age, when the -[GlcAbeta,3GalNAc6]- disaccharide content increased from approximately 50% to 85% of the total disaccharide content and there was a concomitant decrease in the content of the 4-sulfated disaccharide. In general, the disaccharide content of the deeper layers of immature cartilage were richer in the 4-sulfated residue than the upper regions of the tissue. As the tissue aged and decreased in thickness, the disaccharide composition became more evenly 6-sulfated. The newly synthesized chondroitin sulfate chains had a similar composition to the endogenous chains and also underwent the same age and zonal changes. The monoclonal antisera 3B3(+) and 2B6(+) were used to immunolocalize the unsaturated 6- and 4-sulfated residues generated at the reducing termini of the chondroitin sulfate chains by digestion with chondroitin ABC lyase, and these analyses indicated that the sulfation pattern at this position did not necessarily reflect the internal disaccharide composition of the chains. In summary, the sulfation pattern of chondroitin sulfate disaccharides from human normal articular cartilage varies with the age of the specimen, the position (topography) on the joint surface, and the zone of cartilage analyzed. Furthermore, these changes in composition are a consequence of both extracellular, post-translational processing of the core protein of aggrecan and changes in the sulfotransferase activity of the chondrocyte.

Improvement of the BCR three step sequential extraction procedure prior to the certification of new sediment and soil reference materials

The Standards, Measurements and Testing Programme (formerly BCR) of the European Commission proposed a three-step sequential extraction procedure for sediment analysis, following extensive expert consultations and two interlaboratory studies. This scheme was recently used to certify the extractable trace element contents of a sediment reference material (CRM 601). Although this procedure offers a means to ensure the comparability of data in this field, some difficulties concerning the interlaboratory reproducibility still remain, and a new project is currently being conducted to determine the causes of poor reproducibility in the extraction scheme. The final objective of the project is the certification of new sediment and soil reference materials for their extractable contents of Cd, Cr, Cu, Ni, Pb and Zn. This paper presents the results of a small-scale interlaboratory study, which aimed to test a revised version of the extraction schemes by comparing the original and the modified protocols using the CRM 601 sample. This work offers an improvement to the BCR sequential extraction procedure through intercomparison exercises. This improved procedure will allow the obtaining of CRMs to validate analytical data in the analysis of soils and sediments, and it will also facilitate comparability of data in the European Union.

Symptoms reported by elderly patients with isolated systolic hypertension: baseline data from the SYST-EUR trial. Systolic Hypertension in Europe

OBJECTIVES

To determine the symptomatic well-being of elderly persons with isolated systolic hypertension.

DESIGN AND SETTING

Well-being determined during the placebo run-in period prior to entry to the Systolic Hypertension in Europe (SYST-EUR) trial.

SUBJECTS

641 People, 60 years or older with an average sitting blood pressure of 173/86 mm Hg.

OUTCOME MEASURES

33 Symptomatic complaints determined by a standard interview.

RESULTS

The 437 women complained of 25% of the symptoms and the 204 men 21% (P<0.001). A markedly higher prevalence was observed in women compared with men for: pain in the joints of the hands (35% of women complained of this against 22% of men); 'racing heart' (33% against 17%); dry eyes (16% against 6%); blurring of vision (35% against 23%); cramps in the legs (43% against 31%); and a sore throat (15% against 7%). Nocturia was the most frequent complaint (68% in both sexes). Eight symptoms increased with age and one (rash) tended to decline. With increasing systolic pressure women also reported more headaches, unsteadiness, blurring of vision, irregular heart beat and 'racing heart' but, of these, only headaches increased with diastolic pressure. These observations were made after adjusting for age, blood sugar and body mass index (BMI) and were not observed in men. Higher blood sugars were associated with mouth ulcers, 'racing heart', blurring of vision and cramps in the legs. A higher BMI was associated with six symptoms, and a lower age of leaving education with eight. In men, alcohol consumption was related to 'racing heart', and smoking to wheezing and having a dry cough.

CONCLUSIONS

A high level of complaint was associated with female gender, increasing age, blood sugar and BMI and a low age of leaving education.

Calcium channel blockade and cardiovascular prognosis in the European trial on isolated systolic hypertension

In the double-blind Systolic Hypertension in Europe (Syst-Eur) Trial, active treatment was initiated with nitrendipine (10 to 40 mg/d) with the possible addition of enalapril (5 to 20 mg/d) and/or hydrochlorothiazide (12.5 to 25 mg/d) titrated or combined to reduce sitting systolic blood pressure by at least 20 mm Hg to <150 mm Hg. In the control group, matching placebos were used similarly. In view of persistent concerns about the use of calcium channel blockers as first-line antihypertensive drugs, this report explored to what extent nitrendipine, administered alone, prevented cardiovascular complications. Age at randomization averaged 70.2 years and systolic/diastolic blood pressure 173.8/85.5 mm Hg. Of 2398 actively treated patients, 1327 took only nitrendipine (average dose, 23.4 mg/d), and 1042 progressed to other treatments including nitrendipine (n=757; 35.7 mg/d), enalapril (n=783; 13.4 mg/d), and/or hydrochlorothiazide (n=294; 21.0 mg/d). Compared with the whole placebo group (n=2297), patients receiving monotherapy with nitrendipine had 25% (P=0.05) fewer cardiovascular end points, and those progressing to other active treatments showed decreases (P</=0. 01) in total mortality (40%), stroke (59%), and all cardiovascular end points (39%). Among the control patients, 863 used only the first-line placebo. Compared with this subgroup, patients receiving monotherapy with nitrendipine showed a nearly 50% (P</=0.004) reduction of all types of end points, including total and cardiovascular mortality. The full relative benefit from nitrendipine was seen as early as 6 months after randomization. To ascertain that the benefit conferred by the dihydropyridine was not due to selection bias, the 1327 patients remaining on monotherapy with nitrendipine were matched by gender, age, previous cardiovascular complications, and systolic blood pressure at entry with an equal number of placebo patients. In this analysis, nitrendipine reduced (P</=0.05) cardiovascular mortality by 41%, all cardiovascular end points by 33%, and fatal and nonfatal cardiac end points by 33%. Despite the limitations inherent in post hoc analyses, the present findings suggest that the calcium channel blocker nitrendipine, given as a single antihypertensive medication, prevents cardiovascular complications in older patients with isolated systolic hypertension.

Contrasting effects of chronic paroxetine on 5-HT1A control of dorsal raphe cell firing and 5-HT release

To test the role of 5-HT1A receptors in the action of antidepressants, we investigated the effect of chronic paroxetine (10 mg/kg, p.o. for 21 days) on functional assays of 5-HT1A sensitivity. We constructed cumulative concentration response curves to the selective 5-HT1A agonist (+)-8-OH-DPAT on both extracellular recordings of 5-HT neurones and electrically stimulated 5-HT release in dorsal raphe brain slices. Chronic paroxetine desensitized the 5-HT1A receptors controlling firing, with an increase in EC50 from 10.7 nM to 46.2 nM 8-OH-DPAT. Chronic paroxetine did not, however, desensitize the 5-HT1A receptors controlling 5-HT release but increased the 8-OH-DPAT Emax from 54.9% to 79.2% inhibition of 5-HT release. These data suggest that there are either two distinct populations of 5-HT1A receptors or separate second messenger systems, one controlling 5-HT release and another influencing firing. Furthermore chronic paroxetine treatment can differentially modulate these different populations.

Ambulatory blood pressure monitoring and postprandial hypotension in elderly patients with isolated systolic hypertension. Systolic Hypertension in Europe (SYST-EUR) Trial Investigators

The present analysis was undertaken to evaluate postprandial (PP) changes in blood pressure (BP) assessed with ambulatory BP monitoring (ABPM) in elderly subjects with isolated systolic hypertension (ISH) on conventional measurement. A total of 530 patients (335 women and 195 men, aged 60-100 years, median 70 years) who performed an ABPM during the placebo run-in period of the Syst-Eur trial were included into the analysis. The PP changes in BP and heart rate (HR) were calculated by subtracting the mean systolic BP (SBP), diastolic BP (DBP) and HR in the 2 h preceding the main meal from the corresponding means covering the 2 h after the meal. The reproducibility of the postprandial fall in BP and heart rate (PPH) was assessed by contrasting the first and second ABPM in a subgroup of 147 patients who performed two ABPM's during the placebo run-in period. The mean SBP and DBP decreased and reached the nadir 2 h after the main meal while HR did not change. When PPH was assessed by comparing BP in the 2 h before and after the meal, both SBP and DBP decreased significantly (respectively -6.6 mm Hg, -5.4 mm Hg; P < 0.001). In 67.6% of all patients a decrease in SBP was observed and in 24.1% it exceeded 16 mm Hg. The corresponding values for DBP were 71.3% and 24.5% (DBP decreased more than 12 mm Hg). A greater fall in DBP was associated with a greater decrease in HR (r = 0.20, P < 0.001), while changes in SBP and HR were not interrelated. Regression analysis did not identify any significant covariate of PPH. Group means of PPH could be reproduced without significant changes in their values, but the within-subject reproducibility of the PP changes was low. There were no differences in PPH according to the place of residence of the patients. In conclusion, the descriptive analysis of the meal-induced changes in ABPM in elderly subjects with ISH showed that in every day circumstances most of them experience falls in both SBP and DBP within 2 h after the meal.

Actions of tramadol, its enantiomers and principal metabolite, O-desmethyltramadol, on serotonin (5-HT) efflux and uptake in the rat dorsal raphe nucleus

Tramadol is an atypical centrally acting analgesic agent with relatively weak opioid receptor affinity in comparison with its antinociceptive efficacy. Evidence suggests that block of monoamine uptake may contribute to its analgesic actions. Therefore, we have examined the actions of (+/-)-tramadol, (+)-tramadol, (-)-tramadol and O-desmethyltramadol (M1 metabolite) on electrically evoked 5-HT efflux and uptake in the dorsal raphe nucleus (DRN) brain slice, measured by fast cyclic voltammetry. Racemic tramadol and its (+)-enantiomer (both 5 mumol litre-1) significantly blocked DRN 5-HT uptake (both P < 0.05) and increased stimulated 5-HT efflux (P < 0.01 (+/-)-tramadol; P < 0.05 (+)-tramadol). The (-)-enantiomer and metabolite, O-desmethyltramadol, were inactive at the concentration tested (5 mumol litre-1). For both (+/-)-tramadol and the (+)-enantiomer, the action on 5-HT efflux preceded an effect on 5-HT uptake, suggesting that uptake block was not the cause of the increased 5-HT efflux and that tramadol might therefore have a direct 5-HT releasing action. This activity, at clinically relevant concentrations, may help to explain the antinociceptive efficacy of tramadol despite weak mu opioid receptor affinity and adds to evidence that tramadol exerts actions on central monoaminergic systems that may contribute to its analgesic effect.

The mago nashi gene is required for the polarisation of the oocyte and the formation of perpendicular axes in Drosophila

BACKGROUND

Drosophila axis formation requires a series of inductive interactions between the oocyte and the somatic follicle cells. Early in oogenesis, Gurken protein, a member of the transforming growth factor alpha family, is produced by the oocyte to induce the adiacent follicle cells to adopt a posterior cell fate. These cells subsequently send an unidentified signal back to the oocyte to induce the formation of a polarised microtubule array that defines the anterior-posterior axis. The polarised microtubules also direct the movement of the nucleus and gurken mRNA from the posterior to the anterior of the oocyte, where Gurken signals a second time to induce the dorsal follicle cells, thereby polarising the dorsal-ventral axis.

RESULTS

In addition to its previously described role in the localisation of oskar mRNA, the mago nashi gene is required in the germ line for the transduction of the polarising signal from the posterior follicle cells. Using a new in vivo marker for microtubules, we show that mago nashi mutant oocytes develop a symmetric microtubule cytoskeleton that leads to the transient localisation of bicoid mRNA to both poles. Furthermore, the oocyte nucleus often fails to migrate to the anterior, causing the second Gurken signal to be sent in the same direction as the first. This results in a novel phenotype in which the anterior of the egg is ventralised and the posterior dorsalised, demonstrating that the migration of the oocyte nucleus determines the relative orientation of the two principal axes of Drosophila. The mago nashi gene is highly conserved from plants to animals, and encodes a protein that is predominantly localised to nuclei.

CONCLUSIONS

The mago nashi gene plays two essential roles in Drosophila axis formation: it is required downstream of the signal from the posterior follicle cells for the polarisation of the oocyte microtubule cytoskeleton, and has a second, independent role in the localisation of oskar mRNA to the posterior of the oocyte.

Chronic paroxetine desensitises 5-HT1D but not 5-HT1B autoreceptors in rat lateral geniculate nucleus

The present study examined the effect of chronic paroxetine (10 mg/kg p.o., 21 days) on the 5-HT1B and 5-HT1D autoreceptors controlling 5-HT efflux in slices of rat ventrolateral geniculate nucleus. Electrically stimulated 5-HT efflux (10 pulses, 200 Hz, 0.1 ms, 10 mA) was measured using fast cyclic voltammetry. Peak 5-HT efflux was greater (P < 0.01) after chronic paroxetine (22.2 +/- 1.4 nM, mean +/- S.E.M.) than water (15.8 +/- 1.4 nM). 5-HT efflux was inhibited by CP 93129 (1 nM-10 microM) and sumatriptan (1 nM-1 microM), agonists at 5-HT1B and 5-HT1D receptors, respectively. Chronic paroxetine did not affect the sensitivity of the 5-HT1B autoreceptor but shifted the sumatriptan concentration-response curve to the right (P < 0.05). These data suggest that chronic paroxetine increases evoked 5-HT efflux. This may be the result of desensitisation of 5-HT1D but not 5-HT1B autoreceptors.

(+)-WAY 100135, a partial agonist, at native and recombinant 5-HT1B/1D receptors

1. We have studied the effects of the purportedly selective 5-HT1A receptor antagonist (+)-WAY 100135 on electrically stimulated 5-hydroxytryptamine (5-HT) efflux in the ventrolateral geniculate nucleus (vLGN), and its affinity at human 5-HT1B and 5-HT1D receptors stably expressed in Chinese hamster ovary (CHO) cells. 2. On short 'pseudo single pulse' stimulations (20 pulses at 100 Hz, 190 ms train duration), (+)-WAY 100135 (1.0 microM) decreased 5-HT efflux in the vLGN to 68 +/- 8% of pre-drug values (P < 0.01). This decrease could be blocked by the 5-HT1D/1B receptor antagonist GR 127935 (50 nM). Conversely, when long stimulations (20 pulses at 20 Hz, 950 ms train) were used, (+)-WAY 100135 had no effect on 5-HT efflux (84 +/- 8% of pre-drug values) although both methiothepin (200 nM) and GR 127935 (50 nM) caused significant increases (to 175 +/- 18 and 130 +/- 10% of pre-drug values, respectively). 3. Paroxetine (100 nM), the selective 5-HT reuptake inhibitor, increased stimulated 5-HT efflux and reuptake half-life (to 145 +/- 18% and 649 +/- 121%, respectively) on pseudo single pulse stimulations. When (+)-WAY 100135 was added in combination with the uptake blocker, the effect of paroxetine on stimulated 5-HT efflux was potentiated to 282 +/- 48% (P < 0.01) without further effect on the 5-HT reuptake half-life. 4. The affinity and intrinsic activity of (+)-WAY 100135 were determined at recombinant human 5-HT1B and 5-HT1D receptors expressed in CHO cells, by use of radioligand binding and [35S]-GTP gamma S binding (+)-WAY 100135 was a partial agonist at human 5-HT1B and 5-HT1D receptors with moderately high affinity for 5-HT1D receptors (pEC50 = 7.61). 5. In conclusion, (+)-WAY 100135 was found to be not a selective 5-HT1A autoreceptor antagonist but may act as a partial agonist at the 5-HT1B/1D receptor, displaying agonist or antagonist properties depending on the stimulation protocol used and the resultant 5-HT 'tone' at the receptor.

Coronary artery stenting postcardiac transplant: a report of two cases

Coronary atherosclerosis remains a significant cause of morbidity and mortality following cardiac transplantation. Coronary artery bypass grafting, percutaneous transluminal coronary angioplasty, and directional coronary atherectomy have all been presented as attempted treatment options in this population with generally suboptimal results. Endovascular stenting is a new transcatheter treatment modality with unique potential advantages as compared to other transcatheter revascularization techniques. This report presents the use of endovascular stenting and 6-mo follow-up in two orthotopic cardiac transplant recipients with proximal stenotic posttransplant graft atherosclerosis.

Assessment of cardiopulmonary resuscitation in the membership examination of the Royal College of Physicians

The poor performance of doctors in cardiopulmonary resuscitation has been described in several studies. The problem has been addressed in the last few years by simplifying treatment algorithms, establishing standards of competence, and creating a training framework. Resuscitation skills are also assessed during formal examinations such as those for the membership of the Royal College of Physicians (MRCP(UK)). In 1994 and 1996, we assessed the resuscitation skills of the candidates at our centre during the short-case section of the MRCP examination. With the correct preparation, there was no difficulty in carrying out detailed assessment of basic life support, defibrillation and advanced life support. This assessment was carried out separately from that of the examiners and did not interfere with the running of the short cases. The resuscitation skills of this small sample of an important group of doctors in training grades were unsatisfactory, and we suggest that more should be done to raise standards.

Synergism of 5-HT 1B/D antagonists with paroxetine on serotonin efflux in rat ventral lateral geniculate nucleus slices

Serotonin (5-HT) efflux in rat ventral lateral geniculate nucleus (vLGN) slices was evoked by electrical stimulation (20 pulses at 100 Hz, 10 mA, 190 ms train) and measured, along with 5-HT uptake, by fast cyclic voltammetry at implanted carbon fibre microelectrodes. Paroxetine (100 nM), a selective serotonin reuptake inhibitor (SSRI), increased stimulated 5-HT efflux to 194 +/- 25% of pre-drug values at maximum (mean +/- SEM, n = 5) and the half-life of uptake to 684 +/- 135%. When given alone, neither the selective 5-HT 1B antagonist isamoltane (1 microM) nor the 5-HT 1D/B antagonist GR 127935 (50 nM), affected 5-HT efflux or uptake under this stimulation paradigm. When added in combination with paroxetine, both isamoltane and GR 127935 significantly potentiated the effect of paroxetine on stimulated 5-HT efflux: isamoltane to 302 +/- 48% at maximum (p < 0.05 vs. paroxetine alone), GR 127935 to 318 +/- 95% (p < 0.05 vs. paroxetine alone) of pre-drug values. Neither isamoltane nor GR 127935 had any effect on 5-HT uptake. The selective 5-HT 1A antagonist WAY 100635 (10 nM) had no effect on 5-HT efflux or uptake, alone or in combination with paroxetine. These data suggest that, under these experimental conditions, paroxetine gives rise to tonic activation of the vLGN terminal 5-HT autoreceptors. Furthermore, these data show that 5-HT 1B and possibly 5-HT 1D antagonists block this inhibitory autoreceptor tone and may thus be a useful addition to SSRI treatment in the clinic.

Comparison of once daily and twice daily nisoldipine as monotherapy in essential hypertension

Twenty-four patients completed a dose ranging study of the effect of nisoldipine as monotherapy in the treatment of hypertension. This randomized double-blind study consisted of two crossover phases in each of which once and twice daily treatment were compared. In the first treatment phase the total daily dose of nisoldipine was 10 mg, which increased to 20 mg during the second phase. Trough blood pressure measurements were made 12/24 h postdose. During the first phase the blood pressure values following treatment with nisoldipine 5 mg twice daily were significantly lower than with 10 mg once daily. However, when the daily dose was increased to 20 mg there was no significant difference between the two treatment regimens. There was also no significant difference between nisoldipine 5 mg twice daily and 10 mg twice daily but the results for 20 mg once daily were significantly lower than for 10 mg once daily. Four patients withdrew from the study because of adverse events, one while on placebo and three while on nisoldipine therapy. Between 33 percent and 47 percent of patients reported adverse events during nisoldipine treatment but the majority of adverse events reported were mild and did not require treatment withdrawal. Nisoldipine twice daily appeared to be more effective and better tolerated than once daily treatment for 24-h blood pressure control.

Ambulatory monitoring uncorrected for placebo overestimates long-term antihypertensive action. Systolic Hypertension in Europe (SYST-EUR) Trial Investigators

This study compares blood pressure (BP) changes during active antihypertensive treatment and placebo as assessed by conventional and ambulatory BP measurement. Older patients (> or = 60 years, n=337) with isolated systolic hypertension by conventional sphygmomanometry at the clinic were randomized to placebo or active treatment consisting of nitrendipine (10 to 40 mg/d), with the possible addition of enalapril (5 to 20 mg/d) and/or hydrochlorothiazide (12.5 to 25 mg/d). At baseline, clinic systolic/diastolic BP averaged 175/86 mm Hg and 24-hour and daytime ambulatory BPs averaged 148/80 and 154/85 mm Hg, respectively. After 13 months (median) of active treatment, clinic BP had dropped by 22.7/7.0 mm Hg and 24-hour and daytime BPs by 10.5/4.5 and 9.7/4.3 mm Hg, respectively (P<.001 for all). However, clinic (9.8/1.6 mm Hg), 24-hour (2.1/1.1 mm Hg), and daytime (2.9/1.0 mm Hg) BPs decreased also during placebo (P<.05, except for daytime diastolic BP); these decreases represented 43%/23%, 20%/24%, and 30%/23% of the corresponding BP fall during active treatment. After subtraction of placebo effects, the net BP reductions during active treatment averaged only 12.9/5.4, 8.3/3.4, and 6.8/3.2 mm Hg for clinic, 24-hour, and daytime BPs, respectively. The effect of active treatment was also subject to diurnal variation (P<.05). Changes during placebo in hourly systolic and diastolic BP means amounted to (median) 21% (range, -1% to 42%) and 25% (-3% to 72%), respectively, of the corresponding changes during active treatment. In conclusion, expressed in millimeters of mercury, the effect of antihypertensive treatment on BP is larger with conventional than with ambulatory measurement. Regardless of whether BP is measured by conventional sphygmomanometry or ambulatory monitoring, a substantial proportion of the long-term BP changes observed during active treatment may be attributed to placebo effects. Thus, ambulatory monitoring uncorrected for placebo or control observations, like conventional sphygmomanometry, overestimates BP responses in clinical trials of long duration.

Integrated care pathways: effective tools for continuous evaluation of clinical practice

The critical examination of clinical practice should be an integral part of patient care. It includes the development and implementation of guidelines, together with continuous evaluation of clinical process and outcomes to improve the quality of care provided. Clinical audit has not been successful in achieving this. The use of Integrated Care Pathways facilitates the introduction of guidelines and the continuous evaluation of clinical practice. Improvements are achieved by frequently revising the pathways to reflect current, local best practice. Integrated Care Pathways define the expected course of events in the care of a patient with a particular condition, within a set time-scale. A pathway is divided into time intervals during which specific goals and expected progress are defined, together with appropriate investigations and treatment. A pathway reflects the activities of a multidisciplinary team and can incorporate established guidelines and evidence-based medicine. It is usually unique to the institution in which it was developed. The pathway forms part of the clinical record of every patient. All variations from the pathway are documented, and the reasons for the variations analysed. Solutions are developed to address the causes of potentially avoidable variation, and the pathway is revised to incorporate these improvements. Integrated Care Pathways provide a powerful audit tool, as all aspects of the process and outcome of clinical practice can be constantly monitored. Variations from set standards are minimized, and improvements are rapidly incorporated into routine practice and subsequently re-evaluated.

Serotonin efflux in the rat ventral lateral geniculate nucleus assessed by fast cyclic voltammetry is modulated by 5-HT1B and 5-HT1D autoreceptors

Fast cyclic voltammetry (FCV) was used to measure electrically stimulated monoamine efflux in the rat ventral lateral geniculate nucleus (vLGN). The electrochemical characteristics of the released species resembled 5-HT but not dopamine or noradrenaline. Amine efflux was abolished by the sodium channel blocker tetrodotoxin (0.1 microM), Ro 4-1284 (1.0 microM), the fast-acting reserpine analogue, and removal of Ca2+ from the superfusate. Amine efflux was unaffected by the monoamine oxidase inhibitor clorgyline (0.1 microM). Of paroxetine (0.1 microM), desipramine (50 nM) and vanoxerine (0.5 microM), selective blockers of 5-HT, noradrenaline and dopamine uptake respectively, only paroxetine increased monoamine efflux (to 194 +/- 25%, mean +/- SEM) and prolonged the removal half-life (to 638 +/- 105%). The non-specific 5-HT1 antagonist methiothepin (0.2 microM) increased 5-HT efflux on long (20 pulses at 20 Hz) but not short trains (20 pulses at 100 Hz). When tested on pseudo-one-pulse stimulations (5 pulses, 100 Hz), the selective 5-HT1A agonist 8-OHDPAT (1.0 microM) had no effect. CP 93129 (0.3 microM), the selective 5-HT1B agonist, decreased 5-HT efflux to 37 +/- 4% of control and was antagonised by the 5-HT1B blocker isamoltane (0.5 microM) and by the 5-HT1D/B antagonist GR 127935 (50 nM). The preferential 5-HT1D agonist sumatriptan (0.5 microM) also decreased 5-HT efflux, to 55 +/- 6% and was antagonised by GR 127935 (50 nM) but not isamoltane (0.5 microM). These results suggest that 5-HT released in the vLGN can be measured by FCV. Furthermore, released 5-HT is taken up by the 5-HT transporter and may be under the influence of 5-HT1B and 5-HT1D autoreceptors.

Delay times in the administration of thrombolytic therapy: the Brighton experience

We reviewed the effectiveness of a strategy involving paramedic ambulances and community education to reduce the delay to thrombolytic therapy in patients admitted with acute myocardial infarction, by analysing delay times recorded during routine treatment. Rapid identification and treatment of patients with acute myocardial infarction who were eligible for thrombolysis was carried out in the Accident and Emergency and Cardiac Care Units. Two hundred seventy-four patients were admitted with acute myocardial infarction over an 18-month period and treated with anistreplase (168) or streptokinase (106). The following median times were recorded: symptom onset to administration of thrombolytic therapy, 142 min (range 43-980 min); symptom onset to ambulance arrival, 60 min; ambulance with patient to arrival in hospital, 35 min; time to treatment in hospital ('door to needle time'), 25 min; in-hospital delays were notably shorter for patients given anistreplase as opposed to streptokinase. Shortened delays for the delivery of thrombolytic therapy can be achieved by a strategy involving public education, the availability of resuscitation ambulances, and close liaison with the Accident and Emergency Department.

The acceptability of resin therapy to patients attending a hospital lipid clinic

Low dose cholestyramine ('Questran A') and colestipol ('Colestid Orange') were compared in a blinded two period crossover study of 55 patients attending a hospital lipid clinic. Colestipol was rated higher on a combined acceptability/palatability score. Both treatments reduced low density lipoprotein (LDL) cholesterol to a similar extent.

The effect of paroxetine on 5-HT efflux in the rat dorsal raphe nucleus is potentiated by both 5-HT1A and 5-HT1B/D receptor antagonists

Serotonin (5-HT) efflux in slices of rat dorsal raphe nucleus (DRN) was evoked by pseudo one pulse electrical stimulation (20 pulses at 100 Hz, 190 ms train duration) and measured, along with 5-HT uptake, by fast cyclic voltammetry (FCV). The selective serotonin re-uptake inhibitor (SSRI) paroxetine (10(-7) M) increased 5-HT efflux to 147 +/- 6% of pre-drug values at maximum (mean +/- SEM, n = 5) and the half-life of uptake to 443 +/- 38%. The non-selective 5-HT1 antagonist methiothepin (2 x 10(-7) M) increased 5-HT efflux to 147 +/- 9% at maximum but had no effect on uptake half-life. In contrast, (+)-WAY 100135 (10(-6) M) and GR 127935 (5 x 10(-8) M), selective antagonists at 5-HT1A and 5-HT1B/D receptors, respectively, affected neither 5-HT efflux nor uptake. When given in combination with paroxetine, the antagonists significantly increased the effect of paroxetine on efflux: methiothepin to 228 +/- 24% (P < 0.001), (+)-WAY 100135 to 212 +/- 31% (P < 0.05) and GR 127935 to 203 +/- 23% (P < 0.01). These data suggest that, under these experimental conditions, DRN 5-HT autoreceptors are tonically activated in the presence of the uptake blocker and that the antagonists act by blocking this counteracting autoinhibitory tone. The data also strongly indicate that 5-HT efflux in the rat DRN is under the control not only of 5-HT1A but also of 5-HT1B/D receptors.

Evidence that 5-hydroxytryptamine release in rat dorsal raphé nucleus is controlled by 5-HT1A, 5-HT1B and 5-HT1D autoreceptors

Electrically stimulated 5-hydroxytryptamine (5-HT) release was monitored in slices of rat dorsal raphé nucleus (DRN) by fast cyclic voltammetry. Pseudo-single pulse stimulations (5 pulses at 100 Hz) were used to enable the effect of various receptor agonists to be seen without competition from endogenously released transmitter. The selective 5-HT1A receptor agonist, (+)-8-OH-DPAT (1.0 microM) decreased stimulated 5-HT release to 31 +/- 3% of controls. This decrease was inhibited by the 5-HT1A receptor antagonists, (+)-WAY-100135 (1.0 microM) and WAY-100635 (0.1 microM) but not by the 5-HT1D/B antagonist, GR127935 (0.05 microM). The selective 5-HT1B receptor agonist, CP-93129 (0.3 microM) decreased stimulated 5-HT release to 61 +/- 4% of control. This effect was antagonized by the 5-HT1B receptor antagonist, isamoltane (0.5 microM) but not by (+)-WAY-100135. The 5-HT1D agonist, sumatriptan (0.5 microM) decreased stimulated 5-HT release to 52 +/- 2% of controls. This decrease was blocked by GR-127935 but not by WAY-100635. These results suggest that 5-HT release in the rat DRN is under the control of 5-HT1A, 5-HT1B and 5-HT1D autoreceptors.

The effect of age and liver disease on the pharmacokinetics of the calcium antagonist, nisoldipine

Two studies were performed-one in elderly, hypertensive patients and one in patients with chronic liver disease-to investigate the effect of age and liver disease upon the pharmacokinetics of nisoldipine, a dihydropyridine-type calcium antagonist. The effect of acute and chronic administration of nisoldipine (once and twice daily) was investigated in 17 elderly hypertensive patients. Compared with previously published data from young healthy volunteers, the values for Cmax and AUC appear to be higher in elderly hypertensive patients while Tmax and half-life were unchanged. Nisoldipine significantly reduced both systolic and diastolic blood pressure when given acutely to elderly hypertensive patients. Major alterations in the pharmacokinetics of nisoldipine were found in 7 patients with chronic liver disease when compared with the elderly hypertensives and healthy volunteers. The values for AUC, Cmax, half-life and volume of distribution were all higher than expected from the volunteer data while clearance was lower. One patient receiving primidone had very low nisoldipine levels, suggesting that the concomitant administration of agents that may induce the metabolism of nisoldipine should be discouraged. Nevertheless, comparisons of nisoldipine plasma levels after acute and chronic administration showed no evidence of any accumulation in either patient population in the doses used. The drug was generally well tolerated although 1 patient with chronic liver disease was withdrawn due to fluid retention.

A comparison of once daily versus twice daily nisoldipine as monotherapy in patients over 65 years of age

The antihypertensive effect of the calcium antagonist nisoldipine was investigated in 33 elderly hypertensive patients. This randomised double-blind study involved a dose titration of both once and twice daily nisoldipine from 5 mg up to a maximum of 20 mg/day, with placebo treatment both before and after nisoldipine. Blood pressure measurements were made 12/24 h post-dose to assess 24 h blood pressure control. The majority of patients required a daily dose of 20 mg. There were no significant differences seen between the two treatment regimens. Nisoldipine given either once or twice daily, significantly reduced blood pressure when compared to baseline values. Three patients withdrew from the study because of adverse events whilst on nisoldipine once daily treatment. Overall the incidence of adverse event was higher on once daily treatment, although the majority were mild and did not require withdrawal of treatment. Nisoldipine effectively lowered the blood pressure of these elderly hypertensive patients and was reasonably well-tolerated.

Ambulatory pressure decreases on long-term placebo treatment in older patients with isolated systolic hypertension. Syst-Eur Investigators

OBJECTIVE

This long-term study investigated the widely accepted hypothesis that ambulatory pressure does not decrease in patients given placebo.

METHODS

One hundred and twelve older (> or = 60 years) outpatients with isolated systolic hypertension were recruited. Treatment consisted of a placebo during a 3-month baseline period and long-term follow-up.

RESULTS

At baseline, on placebo treatment, clinic systolic/diastolic (SBP/DBP) blood pressure (+/- SD) averaged 176 +/- 12/86 +/- 7 mmHg and 24-h SBP/DBP 151 +/- 15/81 +/- 10 mmHg. These pressures were unaltered in 51 patients in whom the baseline measurements were repeated after a further month on placebo. After the 112 patients had received placebo for 1 year (median), clinic SBP/DBP fell by 6.6 +/- 15.9 (P < 0.001)/1.4 +/- 7.4 (P = 0.06)mmHg and 24-h SBP by 2.4 +/- 10.7 mmHg (P < 0.05), whereas 24-h DBP did not change significantly. The 24-h SBP decreased more with higher baseline level and longer follow-up (5-21 months).

CONCLUSIONS

These findings in older patients with isolated systolic hypertension suggest that in long-term studies the ambulatory pressure may slightly but significantly decrease on a placebo. Like those using conventional sphygmomanometry, long-term studies using non-invasive ambulatory monitoring require a placebo-controlled design.

Campylobacter fetus diarrhea in a Hutterite colony: epidemiological observations and typing of the causative organism

Following a case of Campylobacter fetus sepsis and meningitis in a 4-month-old female member of a Hutterite colony, an epidemiological investigation revealed at least 18 cases of diarrhea in other members of the colony. C. fetus was isolated from 7 of 15 fecal samples submitted from affected persons. A case control study suggested that persons who worked in the abattoir were 2.03 times more likely to have had diarrhea, but none of the risk factors studied were significant. The epicurve of the outbreak was inconclusive as to the likely mode of spread of C. fetus. All of the C. fetus strains isolated from the blood of the infant and from the fecal samples were the same by biochemical and antibiotic susceptibility tests. Pulsed-field gel electrophoresis showed that all isolates produced identical restriction endonuclease patterns and differed from other nonepidemiologically related strains of C. fetus.

Role of cardiorespiratory abnormalities, smoking and dive characteristics in the manifestations of neurological decompression illness

1. Blind analysis of contrast echocardiograms to detect intracardiac shunts, blind analysis of lung function tests for evidence of small airways disease, smoking history and dive characteristics were examined in an attempt to explain neurological symptoms that occurred within 5 min of surfacing from unprovocative dives. 2. Pulmonary abnormalities were significantly more frequent in those divers without intracardiac shunts (50%) than in those with shunts (0%). Smoking was more common in those divers without shunts (55% versus 15%), although this just failed to reach conventional significance levels. Divers without shunts experienced cerebral rather than spinal symptoms after significantly shallower dives with lower tissue nitrogen loads. Depths of dives, tissue nitrogen loads and clinical manifestations in those divers without shunts were similar to the findings in divers who had symptoms after rapid ascents. Despite conservative dive profiles, clinical manifestations in divers with shunts resembled those observed after missed decompression stops. 3. The findings suggest that occult lung disease, and probably smoking, increase the risk of neurological symptoms, even after unprovocative dives, and the similarity of the dive profiles and clinical manifestations to cases with rapid ascents suggest that pulmonary barotrauma and arterial gas embolism are responsible. In divers with intracardiac shunts the different dive profiles and clinical manifestations imply that there is another mechanism, involving different tissue and bubble nitrogen kinetics resulting in venous gas liberation and peripheral amplification in embolized tissues, rather than paradoxical embolism per se.

General medicine and related medical specialties--consultant survey 1991

A census of all consultant physicians in England and Wales was carried out on 2 January 1991 by the Royal College of Physicians of London. The total number, 3,573, agreed closely (97%) with the numbers known to the Department of Health (DoH). Of this total, 1,352 were general physicians. Their commonest specialty interests were cardiology, endocrinology, gastroenterology, and thoracic medicine; one-sixth of the geriatricians held posts with some general medical component. In all specialties there is a bulge in the number of consultants aged 40-50. This will lead to a substantial increase in the number of vacancies in the early part of the next century, and will need careful manpower planning. The proportion of women consultants in medical specialties, with perhaps the exception of dermatology, haematology, and geriatric medicine, remains low at 13%. An adequate 'safety net' of junior staff for the care of adult emergencies was present in most main district hospitals at the time of this census.

Simultaneous "real-time" electrochemical and electrophysiological recording in brain slices with a single carbon-fibre microelectrode

Many previous studies have demonstrated the value of carbon-fibre microelectrodes (CFMs) for single-unit activity recording and for fast cyclic voltammetry. In this report we show that these two independent methodologies can be combined at a single CFM and used to study simultaneous electrochemical and electrophysiological events in brain slices. In superfused slices of rat locus coeruleus, dorsal raphe and substantia nigra, we were able to record stable electrophysiological signals and stimulated monoamine efflux for periods of at least 2 h, thereby allowing quantitative pharmacological interventions. The simultaneous recording of amine efflux and unit activity at the same locus facilitates comparison of drug effects at pre- and post-synaptic sites. Furthermore, the system described here uses commercially available instrumentation. The circuitry is described and examples of its application are shown.

Rigors in tuberculosis

Rigors are not a recognized characteristic of miliary tuberculosis. We report two patients presenting with persistent rigors, thought to be suggestive of acute pyogenic infection, who were subsequently found to have miliary tuberculosis. In both cases, there was significant diagnostic delay. Miliary tuberculosis should therefore be included in the differential diagnosis of any patient presenting with unexplained rigors.

Neurochemical evidence of functional A10 dopamine terminals innervating the ventromedial axis of the neostriatum: in vitro voltammetric data in rat brain slices

The neostriatum (CPu) and nucleus accumbens (NAc) receive their primary dopamine (DA) afferents from the A9 and A10 cell groups, respectively. Anatomical evidence has, however, shown that some clusters of A10 afferents innervate the medial (periventricular) aspect of the CPu14. The present study used fast cyclic voltammetry (FCV) at carbon fibre microelectrodes to locate and measure the size of these clusters on the basis of diagnostic differences in DA efflux in A9 and A10 terminal regions. All experiments were conducted in CPu or NAc slices superfused with oxygenated artificial CSF at 32 degrees C. Carbon fibre microelectrodes were placed 80 microns below the slice surface and bipolar stimulating electrodes were located 200 microns away. Except in experiments where the stimulation frequency, pulse width or number of pulses were investigated, DA efflux was evoked using 0.1 ms, 10 mA pulses applied singly (1p) or in 20 pulse trains (20p) at 50 Hz and monitored using FCV. The CPu was first mapped on the basis of the ratio of 20p:1p DA efflux. The CPu consisted mainly (64%) of low ratio (< 3) sites while the NAc core comprised exclusively high ratio (> 6) loci. Population analysis revealed a small percentage (10%) of striatal sites with high (> 6) ratios. These high ratio sites matched the reported distribution of A10 afferent clusters, being found almost entirely along the ventromedial axis of the CPu. Individual clusters of high ratio sites (20p:1p ratios > 6), 'mapped' on the basis of evoked 20p DA efflux, were found to be irregular in outline and around 500 microns across. In order to characterise the clusters further, the influence of stimulation frequency, train duration (number of pulses) and pulse width on DA efflux were examined. Peak DA efflux in the clusters and NAc occurred at 50 Hz while the striatal matrix had a flat frequency response. Both clusters and NAc showed a similar dependence of DA efflux on the number of pulses in the stimulus train. In the CPu matrix, DA efflux was less dependent on the number of pulses. In the striatal matrix, increasing the stimulation pulse width enhanced DA efflux on trains more than on single pulses while, in both NAc and striatal clusters, there was no preferential effect on trains. The medial location of these clusters within the CPu more closely matches the anatomical distribution of the A10 afferents of Gerfen et al. than the more evenly dispersed striosomes.(ABSTRACT TRUNCATED AT 400 WORDS)

A decision aid for diagnosis of liver lesions on MRI

Abdominal magnetic resonance imaging (MRI) plays an important role in the evaluation of liver abnormalities. The interpretation of MR images requires expert training in a rapidly changing field. DAFODILL (Decision Aid for Diagnosing Liver Lesions) is a decision-support tool designed to aid radiologists in the diagnosis of hepatic lesions seen on MRI. DAFODILL uses a knowledge base of MRI findings and a belief-network inference engine to generate probabilistic differential diagnoses of the most commonly encountered hepatic lesions. DAFODILL performs limited image processing to identify clinically relevant features, which are presented to the user for confirmation before they are used by the network. Preliminary evaluation of an initial version of the system suggests that DAFODILL may be a useful tool for radiology residents and nonexpert radiologists in interpreting MR images of the liver.