Suppression of aggregation and calcium mobilisation in bovine platelets by external magnesium

We have examined the effect of increasing external Mg2+ and removing external Ca2+ on bovine platelet activation (measured by time taken for OD to recover to basal following shape change) and thrombin-induced Ca2+ transients. Increasing Mg2+ prolonged the duration of the recovery, both with and without external Ca2+, whereas Mg2+ removal shortened this parameter. In resting platelets, increasing external Mg2+ to 2.5 mM or above reduced basal [Ca2+](i), but had no significant effect when external Ca2+ was removed. Increasing external Mg2+ altered the time-course of the thrombin-induced rise in [Ca2+](i) with or without [Ca2+](o). There was no significant change in OD in a platelet suspension exposed to the highest dose (20 mM) of [Mg2+](o), indicating that the observed effects were not accompanied by significant changes in cell volume. These results suggest that (a) the effect of Mg2+ on bovine platelet function and Ca2+ mobilisation occurs through Ca2+-dependent and Ca2+-independent mechanisms, and (b) significant aggregation can occur in bovine platelets even in the absence of external Ca2+.

Randomized phase II trial of cisplatin/gemcitabine with or without LY293111, a multiple eicosonaid pathway modulator, in patients with chemotherapy naïve advanced non-small cell lung carcinoma

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Background: The eicosanoid pathway is altered in NSCLC. Pharmacological activators of peroxisome proliferator-activated receptor-gamma (PPARγ) have been shown to inhibit lung tumors in vitro. LY293111 inhibits the eicosanoid pathway, is a PPARγ agonist and modulates adipophilin and adiponectin expression levels in vitro. LY293111 is well tolerated and can be administered with cisplatin/gemcitabine. A randomized phase II study in NSCLC was undertaken. Methods: Pts with stage IIIB/IV NSCLC were randomized to two doses of LY293111 (200 mg BID (Arm A) or 600 mg BID (Arm B) or placebo (Arm C) alone for 7 days followed by concurrent cisplatin (75 mg/m2;d1) and gemcitabine (1250 mg/m2;d1,8) q21 days. Treatment was continued until disease progression or toxicity. Primary endpoint was PFS with 75% power to detect 33% improvement compared to placebo (5 months). Calculated sample size was 65 pts/arm (195 total) with a one sided type I error of 0.2. Changes in adipophilin mRNA expression and adiponectin serum levels were assessed at baseline and day 7. Results: Between 09/03 and 07/04, 201 pts were randomized and 195 treated. Demographics (all pts): M:F (65%:35%); median age 61 (range 27–87); stage IIIB/IV (15%:85%); ECOG PS (0:36%;1:64%). Demographics were well balanced between the 3 arms. Most common CTC grade 3/4 toxicities were nausea (8%), vomiting (7%), fatigue (6%) and diarrhea (6%) with only diarrhea related to dose of LY293111 (p=0.03). Response rates (CR+PR) were similar in all 3 arms (A:20%; B:27%; C:21%). There was no significant difference in median PFS (95% CI) between the arms (A: 4.6 months (3.2–5.0); B:6.0 months (4.6–7.2); C:6.0 months (5.2–7.0)). Median survival (95% CI) was similar in all 3 arms (A: 7.3 months (6.2–9.4); B:7.9 months (7.2–9.7); C: 9.0 months (7.7–12.5). Median change in serum adiponectin levels at d7 were significantly higher in arm B vs. placebo (p < 0.05). Adipophilin expression at d7 was increased in a dose dependent manner (p=NS) in arms A and B vs. placebo. Conclusions: LY293111 in combination with cisplatin/gemcitabine did not increase median PFS compared to placebo in pts with NSCLC. Pharmacodynamic modulation was observed but did not impact efficacy.

[Table: see text]

Quality of life measurement in the head and neck cancer radiotherapy clinic: is it feasible and worthwhile?

Quality of Life (QOL) is now a standard end-point in clinical trials. The aim of this non-cohort study was to assess the practical issues surrounding the collection of QOL data in a non-trial setting, and to determine whether it is feasible and worthwhile. Ninety-two patients attending clinics before, or at least 3 months after radiotherapy for head and neck cancer were asked to complete the University of Washington QOL questionnaire (Version 4) and the Hospital Anxiety and Depression Scale. The three most important QOL domains cited by patients after radiotherapy related to saliva production, swallowing and taste. Most patients were able to complete both questionnaires in less than 10 min and reported little difficulty in understanding and completing them. The questionnaires indicated possible clinically significant levels of anxiety and depression in 31% and 16%, respectively. We perceived several benefits of routine QOL data collection in the clinic and this has now been adopted in our own practice.

L-H transition in the mega-amp spherical tokamak

H-mode plasmas have been achieved on the MAST spherical tokamak at input power considerably higher than predicted by conventional threshold scalings. Following L- H transition, a clear improvement in energy confinement is obtained, exceeding recent international scalings even at densities approaching the Greenwald density limit. Transition is accompanied by an order-of-magnitude increase in edge-density gradient, a marked decrease in turbulence, the efficient conversion of internal electron Bernstein waves into free space waves, and the onset and saturation of edge poloidal rotation.

9-cis-retinoids: biosynthesis of 9-cis-retinoic acid

Retinoids function through conformational alterations of ligand-dependent nuclear transcription factors, the retinoic acid receptors, and retinoid X receptors. 9-cis-Retinoic acid is a known biological ligand for retinoid X receptors, but its synthesis pathway in vivo is largely unknown. Recently, we identified a cis-retinol dehydrogenase (cRDH) that oxidizes 9-cis-retinol to 9-cis-retinal. Since both the expression of cRDH mRNA and its substrate are found in liver, we studied 9-cis-retinol metabolism and 9-cis-retinoic acid biosynthesis in two hepatic-derived cell types, Hep G2 hepatoma cells and HSC-T6 stellate cells. Both cell lines accumulate similar amounts of 9-cis-retinol provided in the medium. However, Hep G2 cells preferentially incorporate all-trans-retinol when equimolar concentrations of all-trans- and 9-cis-retinol were provided. In contrast, HSC-T6 cells did not exhibit a preference between all-trans- and 9-cis-retinol under the same conditions. Esterification of 9-cis-retinol occurred in both cell types, likely by acyl-CoA:retinol acyltransferase and lecithin:retinol acyltransferase. In vitro enzyme assays demonstrated that both cell types can hydrolyze 9-cis-retinyl esters via retinyl ester hydrolase(s). In Hep G2 cells, 9-cis-retinoic acid synthesis was strongly inhibited by high concentrations of 9-cis-retinol, which may explain the low levels of 9-cis-retinol in liver of mice. Cell homogenates of Hep G2 can convert all-trans-retinol to 9-cis-retinal, suggesting that the free form of all-trans-retinol may be used as a source for 9-cis-retinol and, thus, 9-cis-retinoic acid synthesis. Our studies provide the basis for identification of additional pathways for the generation of 9-cis-retinoic acid in specialized tissues.

H-Mode operation in the START spherical tokamak

H-mode operation has been achieved in high current (I(p)>200 kA) plasmas in the START spherical tokamak for both neutral-beam-injection-heated and Ohmic discharges. The transition to H mode features the development of well-defined edge pedestals in density and temperature, which signifies the formation of an edge-transport barrier, and associated edge-localized modes. Recent operation at plasma currents exceeding 250 kA shows that these features are accompanied by increases in energy confinement time. This is the first clear demonstration of the H-mode regime in a spherical tokamak.

Metabolism of angiotensin-(1-7) by angiotensin-converting enzyme

Angiotensin converting enzyme (ACE) inhibitors augment circulating levels of the vasodilator peptide angiotensin-(1-7) [Ang-(1-7)] in man and animals. Increased concentrations of the peptide may contribute to the antihypertensive effects associated with ACE inhibitors. The rise in Ang-(1-7) following ACE inhibition may result from increased production of the peptide or inhibition of the metabolism of Ang-(1-7)-similar to that observed for bradykinin. To address the latter possibility, we determined whether Ang-(1-7) is a substrate for ACE in vitro. In a pulmonary membrane preparation, the ACE inhibitor lisinopril attenuated the metabolism of low concentrations of 125I-Ang-(1-7). The primary product of 125I-Ang-(1-7) metabolism was identified as Ang-(1-5). Using affinity-purified ACE from canine lung, HPLC separation and amino acid analysis revealed that ACE functioned as a dipeptidyl carboxypeptidase cleaving Ang-(1-7) to the pentapeptide Ang-(1-5). The ACE inhibitors lisinopril and enalaprilat (1 micromol/L), as well as the chelating agents EDTA, o-phenanthroline, and DTT (0.1-1 mmol/L) abolished the generation of Ang-(1-5) and did not yield other metabolic products. Ang-(1-5) was not further hydrolyzed by ACE. Kinetic analysis of the hydrolysis of Ang-(1-7) by ACE revealed a substrate affinity of 0.81 micromol/L and maximal velocity of 0.65 micromols min(-1) mg(-1). The calculated turnover constant for the peptide was 1.8 sec(-1) with a catalytic efficiency (Kcat/Km) of 2200 sec(-1) mmol/L(-1). These findings suggest that increased levels of Ang-(1-7) following ACE inhibition may be due, in part, to decreased metabolism of the peptide.

Leeds Undergraduate Medical Education Conference, 7-8 July 1995

The Leeds Undergraduate Medical Education Conference (LUMEC) was held on 7-8 July 1995. This conference, devoted entirely to undergraduate medical education, was unique in that it was organized entirely by four medical students. It attracted a wide and enthusiastic audience and excellent speakers. Professor Charles George (Chairman, Education Committee, General Medical Council) spoke about Tomorrow's Doctors, Dr Mark Bailey (Part-chairman, Medical Students' Committee of the British Medical Association) responded with 'Today's Students on Tomorrow's Doctors', and Dr Fleur Fisher (Ethics, Science and Information Division, British Medical Association) focused on the central place of ethics and communication skills in medicine. Professor Sam Leinster (Director of Medical Studies, Liverpool University) and Professor Tim de Dombal (Director, Clinical Information Science Unit, Leeds University) debated the need for new technology and radical change in the curriculum. Finally, Dr Stella Lowry (International Division, British Medical Association) considered the assessment of staff and Mrs Joy Crosby (Curriculum Facilitator, Dundee Medical School) discussed the assessment of students. Discussions focused on a variety of areas, including the need for change, the control of the money available for teaching and the problems of assessment.

A reevaluation of antibiotic prophylaxis in laparoscopic cholecystectomy

Antibiotic prophylaxis for cholecystectomy, although somewhat controversial, is nevertheless a routine component of surgical care. With the advent of laparoscopic cholecystectomy, this routine practice of antibiotic prophylaxis needs to be reevaluated. The present investigation was undertaken to determine the incidence of postsurgical infection in patients receiving antibiotic prophylaxis compared with patients receiving chlorhexidine gluconate scrub the evening before surgery. A total of 448 patients were enrolled in the study. Thirty-two of these patients were excluded because of the presence of intrinsic risk factors for infection. Two hundred twenty-eight patients received antibiotic prophylaxis, and 188 patients were enrolled in the non-antibiotic group. A total of 14 infections occurred in the antibiotic prophylaxis group, whereas no infections occurred in the chlorhexidine group. These results suggest that meticulous antiseptic skin cleansing is sufficient for prevention of postsurgical infection following laparoscopic cholecystectomy. Antibiotic prophylaxis should be used only in those patients exhibiting intrinsic risk factors, such as cholecystitis.

Problem-solving for better health

An outline is given of an approach to the health-for-all goals which involves optimizing resource use, prioritizing people's well-being, achieving excellence and a measurable impact at all levels of care, and solving health problems in a broad developmental context.

Collaboration in coronary heart disease prevention

Health visitors are ideally placed in primary care to offer effective dietary and life-style advice as part of a team approach to coronary heart disease prevention, write Alan Jones et al. Results from a dietary and life-style intervention trial programme suggest that dietitians, who are limited in numbers, should be used as a resource to provide expert dietary advice and training to the more numerous health visitors. In this way CHD risk factor identification can be developed into effective intervention.

A high incidence of asthma and respiratory symptoms in 4-11 year old children

A study assessing the prevalence of respiratory symptoms in two primary schools in Birmingham, U.K. was performed. A questionnaire was delivered to pupils in both schools after which three open days were conducted in one of the schools, where probable asthmatics were identified and referred to their General Practitioner, Chest Clinic or a school asthma clinic. In this school 49% of responders and 52.9% in the control school were symptomless on questionnaire: 31% and 20.8%, respectively, had probable asthma, falling to 20% and 15.5% if a positive response to the question on recent recurrent wheeze was disregarded as indicating asthma. Using the total population as a denominator, the overall asthma prevalence was 20% which is significantly higher compared to previous English rates. Forty-two were seen at the Chest Clinic, 14 being followed for more than two visits. None were on regular anti-asthma treatment initially; 12/14 were taking prophylactic treatment on follow-up. In the two schools, 10.0% and 14.2% of responders were 'chesty' with 'colds' having no other typical asthmatic symptoms: these children should be studied further. This high incidence of respiratory symptoms in primary school children could represent a national trend or just a local increase.

The effect of symptom presentation on delay in asthma diagnosis in children in a general practice

Analysis of 187 children diagnosed as having asthma since 1984 in a general practice population is described. Reasons were sought for possible delay in diagnosis so that appropriate steps could subsequently be taken to minimize further delay. Even in an asthma aware practice (original prevalence 8.8%) a delay of approximately 40% of the total age of the child at diagnosis is shown. This delay does not appear to diminish even for children up to 10 years of age. Asthma is more likely to be missed or labelled as 'bronchitis' in children who cough repeatedly, rather than those who wheeze occasionally. As many as 45% of asthmatic children may have had 'bronchitis' diagnosed and treated instead of asthma, so that a diagnosis of repeated 'bronchitis' merely detracts from underlying asthma.