Extreme diversity, conservation, and convergence of spider silk fibroin sequences

Spiders (Araneae) spin high-performance silks from liquid fibroin proteins. Fibroin sequences from basal spider lineages reveal mosaics of amino acid motifs that differ radically from previously described spider silk sequences. The silk fibers of Araneae are constructed from many protein designs. Yet, the repetitive sequences of fibroins from orb-weaving spiders have been maintained, presumably by stabilizing selection, over 125 million years of evolutionary history. The retention of these conserved motifs since the Mesozoic and their convergent evolution in other structural superproteins imply that these sequences are central to understanding the exceptional mechanical properties of orb weaver silks.

Comparative CD4 T-cell responses of reverse transcriptase inhibitor therapy with or without nelfinavir matched for viral exposure

BACKGROUND

Therapy of HIV infection with protease inhibitors (PIs) may be associated with improvements in CD4 T-cell number via a mechanism that is independent of effects on plasma viral load (VL).

PURPOSE

To compare CD4 responses of patients who receive reverse transcriptase inhibitor (RTI) therapies with or without a PI, matched for viral exposure.

METHODS

Patient data were analyzed from two prospective randomized trials of antiviral therapy with or without nelfinavir. Total viral exposure over 24 weeks was estimated by viral area under the curve (AUC), which reflects baseline viral load, slope of virologic decay, viral nadir, and duration of suppression. Patients were stratified into quartiles on the basis of viral AUC, and CD4 T-cell responses were evaluated between PI-containing and RTI-only treatment groups within each quartile.

RESULTS

In both trials, patients receiving nelfinavir had greater CD4 T-cell increases than patients receiving RTI alone. Analysis of variance modeling revealed increased CD4 T-cell responses in PI-treated groups at all time points after the second week. These differences were significant (p <.05) at weeks 12, 24, 28, 32, 36, 40, and 48 in one study, and weeks 1, 2, 4, 6, 8, 12, 16, 20, 24, 28, 32, 36, and 44 in the other. Within quartiles matched for viral AUC, absolute CD4 T-cell change from baseline was greater in the PI-treated patients at 84% (101/120) of time points analyzed.

CONCLUSION

Nelfinavir-containing therapy is associated with enhanced increases in CD4 T-cell number compared to RTI therapy alone with equivalent antiviral effect. These data suggest that PIs influence CD4 T-cell number through a nonvirologic effect.

Angular malalignment after intramedullary nailing of femoral shaft fractures

OBJECTIVES

To determine factors associated with angular malalignment of femoral shaft fractures treated with intramedullary nails and to determine differences in the incidence of angular malalignment based on fracture location, fracture comminution, and method of treatment (i.e., antegrade or retrograde).

DESIGN

Retrospective.

SETTING

Level I trauma center.

PATIENTS

Three hundred sixty patients with 374 femoral shaft fractures were identified from a prospectively obtained orthopaedic trauma database. Complete sets of immediate postoperative anteroposterior and lateral radiographs were available for 355 (95 percent) of the 374 fractures.

INTERVENTION

Patients were treated with antegrade (183 cases) or retrograde (174 cases) intramedullary femoral nailing.

MAIN OUTCOME MEASURE

Goniometric measurements were made on all immediate postoperative radiographs to determine the coronal plane and sagittal plane angular alignments. A multiple linear regression statistical analysis was used to determine factors associated with increasing angular malalignment. The incidence of malalignment was determined using more than 5 degrees of deformity in any plane as the definition of malalignment.

RESULTS

Proximal fracture location, distal fracture location, and unstable fracture pattern were associated with increasing fracture angulation (p < 0.001). Fracture location in the middle third, stable fracture pattern, method of treatment (i.e., antegrade or retrograde), and nail diameter were not associated with increasing fracture angulation (p > 0.05). The incidence of malalignment was 9 percent for the entire group of patients, 30 percent when the fracture was of the proximal third of the femoral shaft, 2 percent when the fracture was of the middle third, and 10 percent when the fracture was of the distal third. The incidence of malreduction was 7 percent for patients with stable fracture patterns and 12 percent for those with unstable fracture patterns.

CONCLUSIONS

Patients with fractures of the proximal third of the femoral shaft treated with intramedullary nails are at highest risk for malalignment. Proximal fracture location, distal fracture location, and unstable fracture pattern are associated with increasing fracture angulation.

Use of rank-order analysis of ordinal exposure data: application to vinyl chloride exposure

The University of Louisville currently maintains a database of work histories and exposure rankings for chemicals used in the production of polyvinyl chloride from the plant where the original angiosarcoma cases were identified. A 6-point ranking scale was used to characterize worker exposure to vinyl chloride by year, building, and job. Since this is ordinal data, non-parametric statistics have been used to evaluate exposure factors in case-control studies. Rank order analysis of vinyl chloride exposure and angiosarcoma shows a strong statistical association. In contrast, the method shows no association between vinyl chloride exposure and brain cancer. Exposure ranking is a reasonable alternative to estimation of actual dose. Rank order analysis allows for a rapid assessment of exposure-disease associations for case control studies.

Venous thromboembolism after acute stroke

BACKGROUND

Treatment for venous thromboembolism (VTE) is highly effective in preventing morbidity and mortality, yet pulmonary embolism (PE) accounts for up to 25% of early deaths after stroke. This is because the current diagnostic paradigm is reactive rather than proactive: the clinician responds to VTE when it becomes symptomatic, in the expectation that initiation of treatment will prevent progression to more serious manifestations. This approach is flawed, because sudden death from PE is frequently unheralded and nonfatal symptomatic pulmonary emboli are often unrecognized or misdiagnosed.

SUMMARY OF COMMENT

Morbidity and mortality from PE could be reduced either by more effective thromboprophylaxis or earlier diagnosis and treatment of established VTE. The fact that early use of short-term, low-dose, unfractionated heparin (UFH) is not associated with sustained, clinically meaningful benefit suggests that a fundamental change in the diagnostic approach to VTE is needed, one which requires a greater appreciation that clinically apparent events are merely the tip of the thromboembolism iceberg.

CONCLUSIONS

Research into a strategy of screening for subclinical VTE in these patients is needed, with a view to identifying a subgroup at risk of progression to symptomatic and life-threatening events, in whom outcome might be improved by anticoagulation.

A voxel-by-voxel analysis of [18F]setoperone PET data shows no substantial serotonin 5-HT(2A) receptor changes in schizophrenia

Several postmortem studies have reported regionally localized decreases in serotonin(2A) receptors (5-HT(2A)R) in schizophrenia. This was not confirmed by two recent [18F]setoperone positron emission tomography (PET) studies. In these two studies relatively large regions of interest (ROIs) were used; hence, 5-HT(2A)R changes may have been missed in some brain areas. Therefore, data from one study were analyzed on a voxel-by-voxel basis using Statistical Parametric Mapping (SPM). We also used this method to examine the relationship between 5-HT(2A)R binding potential (BP) and five PANSS-derived factors: negative, positive, activation, dysphoric and autistic preoccupation. Thirteen schizophrenic patients (10 antipsychotic-naïve, 3 antipsychotic-free; 11 M, 2 F; age 31+/-7 years) and 35 age-matched control subjects (15 M, 20 F; age 30+/-7 years) were scanned. The 5-HT(2A)R BP was determined for each voxel using the pseudoequilibrium ratio method on PET data obtained between 65 and 90 min after [18F]setoperone bolus injection. The resulting parametric 5-HT(2A)R BP images were spatially normalized using a ligand specific template. Analyses of covariance were done using SPM99 with age as covariate. In tests for the effect of schizophrenia and for partial correlations between 5-HT(2A)R BP and the five factors, corrected P values <0.05 at cluster or voxel level were considered significant. No significant differences were detected between patients and control subjects, and no significant correlations were observed between 5-HT(2A)R BP and any of the five factors. Thus, in agreement with the previous ROI studies, voxel-by-voxel analysis confirmed the lack of substantial 5-HT(2A)R BP differences between schizophrenic patients and control subjects.

Review of intraurethral suppositories and iontophoresis therapy for erectile dysfunction

This brief review examines the history of the intraurethral (IU) pharmacotherapy for the treatment of erectile dysfunction (ED). Emphasis is placed on the design, study endpoints and results of a limited number of clinical trials undertaken with PGE(1)-MUSE to demonstrate the efficacy of this unique delivery system. Next, the theory of the iontophoretic technique of drug delivery is discussed. Clinical data collected while applying these methods are presented, but are thus far limited to treatment of patients with Peyronie's disease. Iontophoresis as a drug delivery alternative may gain popularity with ED patients who fail other types of therapy or in patients with other penile disorders. International Journal of Impotence Research (2000) 12, Suppl 4, S86-S90.

Effectiveness of incidence thresholds for detection and control of meningococcal meningitis epidemics in northern Togo

BACKGROUND

Early outbreak detection is necessary for control of meningococcal meningitis epidemics. A weekly incidence of 15 cases per 100 000 inhabitants averaged over 2 consecutive weeks is recommended by the World Health Organization (WHO) for detection of meningitis epidemics in Africa. This and other thresholds are tested for ability to predict outbreaks and timeliness for control measures.

METHODS

Meningitis cases recorded for 1990-1997 in health centres of northern Togo were reviewed. Weekly and annual incidences were determined for each district. Ability of different weekly incidence thresholds to detect outbreaks was assessed according to sensitivity, specificity, and positive and negative predictive values. The number of cases potentially prevented by reactive vaccination in 1997 was calculated for each threshold.

RESULTS

Outbreaks occurred in 1995-1996 and in 1996-1997. The WHO-recommended threshold had good specificity but low sensitivity. Thresholds of 10 and 7 cases per 100,000 inhabitants in one week had sensitivity and specificity of 100% and increased the time available for intervention by more than one or two weeks, respectively. A maximum of 65% of cases could have been prevented during the 1997 epidemic, with up to 8% fewer cases prevented for each week of delay in achieving vaccine coverage.

CONCLUSIONS

In northern Togo, thresholds of 7 or 10 cases per 100,000 inhabitants per week were excellent predictors of meningitis epidemics and allowed more time for a reactive vaccination strategy than current recommendations.

Doctors' pay. What seems to be the trouble?

The long-standing method of paying GPs through a complex system of fees and allowances is under review. The proposed expansion of personal medical services pilots and an increase in the number of salaried GPs could destabilise the current system and lead to perverse outcomes. The introduction of a weighted capitation system allocating resources to health authorities and primary care trusts according to need might ensure equitable distribution of funds.

Accuracy of the OMRON M4 automatic blood pressure measuring device

Despite widespread use of the automatic blood pressure (BP) measuring device OMRON M4, there is little formal validation on its accuracy. A study was conducted to assess the accuracy of the OMRON M4 compared with the true indirect BP measured by mercury sphygmomanometer (MS). A rapid method for the evaluation of automatic blood pressure measurement devices (READ) was applied for this study. The READ is based on numerous BP measurements at rest and during a standardised postural challenge in a small number of subjects who exhibit a wide range of BPs. Blood pressure measurements were done in supine position for 10 min followed by head-up tilt for 30 min and again supine for 10 min. The automatic device (AU) and the MS were connected to one arm-cuff by means of a T connector. A stethoscope with dual sets of ear-pieces was used for duplicate MS measurements (MS1 and MS2). The MS1, MS2 and AU measurements were taken simultaneously in a blinded manner. Three units of the automatic instrument were evaluated. An average of 111 measurements per unit were performed, every BP category being present in >/=15 MS measurements. The differences between MS1 and MS2 measurements (DeltaBP: MS1-MS2) were utilized to assess the consistency of true indirect BP and the differences between AU and MS measurements (DeltaBP:AU-MS2) were utilized to assess the accuracy of the AU. The following characteristics of the OMRON M4 were assessed: (1) grade of accuracy, (2) aberration pattern, (3) consistency of the aberration-pattern, and (4) correlation between levels of BP and DeltaBP: AU-MS. For MS paired readings, 92-100% of systolic and 99-100% of diastolic readings fell within 5 mm Hg difference range, that is consistent with a British Hypertension Society grade A of both. For AU compared to MS2, 29-64% of systolic and 73-94% of diastolic readings fell within 5 mm Hg and 49-86% of systolic and 86-99% of diastolic readings fell within 10 mm Hg and the devices qualified C, D and C, respectively. All devices exhibited irregular and inconsistent aberration patterns, making the design of correction formulas impractical. In conclusion, the OMRON M4 device did not meet the requirements of the British Hypertension Society and, therefore, cannot be recommended for clinical use.

The design of a practical and reliable fall detector for community and institutional telecare

Falls are one of the greatest obstacles to independent living for frail and elderly people. Their early detection is an important step in providing people with the reassurance and confidence necessary to maintain an active lifestyle. We have investigated a worn fall detector linked to a community alarm system. A worn device is the only one which is satisfactory, provided that it generates few false alarms. The fall detector we have developed is the size of a small radio pager. It uses a two-stage detection process which senses shock and the orientation of the wearer. A fall is detected within 20 s and triggers a radio signal to a community alarm system. Tests were devised using a jointed mannequin to simulate five modes of falling to understand the effects of impact at different parts of the body. This allowed us to select the appropriate trigger threshold and wearing positions for the sensor. Prototypes were evaluated with 20 people to observe false alarms. The final design allowed reliable detection in 180 different falling scenarios.

Consumer demand in the purchase and prescription of sugar-free medicines

OBJECTIVES

To determine the current level of consumer demand in the purchase and prescription of sugar-free paediatric medicines.

DESIGN

Data were collected by administered questionnaire.

SETTING

The study was conducted in a Hospital Paediatric Dentistry Unit and a Community Dental Clinic, both within the Bro Taf area of south-east Wales.

SAMPLE AND METHODS

The parents of 240 children attending for routine dental care responded to one of two short questionnaires, depending on whether their child had received a liquid oral medicine in the preceding month.

RESULTS

Although aware of the benefits of sugar-free medicines, parents did not appear to be attempting to exercise the power of consumer demand to its full potential. They were more likely to ask a pharmacist (or pharmacist's assistant) than their general medical practitioner for a sugar-free medicine.

CONCLUSIONS

We must continue to promote sugar-free medicines. While increasing the importance that health professionals attach to such products, future campaigns should also aim to increase consumer demand.

Structure-activity relationships of omega-conotoxins at N-type voltage-sensitive calcium channels

Due to their selectivity towards voltage-sensitive calcium channels (VSCCs) omega-conotoxins are being exploited as a new class of therapeutics in pain management and may also have potential application in ischaemic brain injury. Here, the structure-activity relationships (SARs) of several omega-conotoxins including GVIA, MVIIA, CVID and MVIIC are explored. In addition, the three-dimensional structures of these omega-conotoxins and some structurally related peptides that form the cysteine knot are compared, and the effects of the solution environment on structure discussed. The diversity of binding and functional assays used to measure omega-conotoxin potencies at the N-type VSCC warranted a re-evaluation of the relationship between these assays. With one exception, [A22]-GVIA, this analysis revealed a linear correlation between functional (peripheral N-type VSCCs) and radioligand binding assays (central N-type VSCCs) for the omega-conotoxins and analogues that were tested over three studies. The binding and functional results of several studies are compared in an attempt to identify and distinguish those residues that are important in omega-conotoxin function as opposed to those that form part of the structural scaffold. Further to determining what omega-conotoxin residues are important for VSCC binding, the range of possible interactions between the ligand and channel are considered and the factors that influence the selectivity of MVIIA, GVIA and CVID towards N-type VSCCs examined.

Roles for ephrins in positionally selective synaptogenesis between motor neurons and muscle fibers

Motor axons form topographic maps on muscles: rostral motor pools innervate rostral muscles, and rostral portions of motor pools innervate rostral fibers within their targets. Here, we implicate A subfamily ephrins in this topographic mapping. First, developing muscles express all five of the ephrin-A genes. Second, rostrally and caudally derived motor axons differ in sensitivity to outgrowth inhibition by ephrin-A5. Third, the topographic map of motor axons on the gluteus muscle is degraded in transgenic mice that overexpress ephrin-A5 in muscles. Fourth, topographic mapping is impaired in muscles of mutant mice lacking ephrin-A2 plus ephrin-A5. Thus, ephrins mediate or modulate positionally selective synapse formation. In addition, the rostrocaudal position of at least one motor pool is altered in ephrin-A5 mutant mice, indicating that ephrins affect nerve-muscle matching by intraspinal as well as intramuscular mechanisms.

Regular exercise enhances insulin activation of IRS-1-associated PI3-kinase in human skeletal muscle

Insulin action in skeletal muscle is enhanced by regular exercise. Whether insulin signaling in human skeletal muscle is affected by habitual exercise is not well understood. Phosphatidylinositol 3-kinase (PI3-kinase) activation is an important step in the insulin-signaling pathway and appears to regulate glucose metabolism via GLUT-4 translocation in skeletal muscle. To examine the effects of regular exercise on PI3-kinase activation, 2-h hyperinsulinemic (40 mU. m(-2). min(-1))-euglycemic (5.0 mM) clamps were performed on eight healthy exercise-trained [24 +/- 1 yr, 71.8 +/- 2.0 kg, maximal O(2) uptake (VO(2 max)) of 56.1 +/- 2.5 ml. kg(-1). min(-1)] and eight healthy sedentary men and women (24 +/- 1 yr, 64.7 +/- 4.4 kg, VO(2 max) of 44.4 +/- 2.7 ml. kg(-1). min(-1)). A [6, 6-(2)H]glucose tracer was used to measure hepatic glucose output. A muscle biopsy was obtained from the vastus lateralis muscle at basal and at 2 h of hyperinsulinemia to measure insulin receptor substrate-1(IRS-1)-associated PI3-kinase activation. Insulin concentrations during hyperinsulinemia were similar for both groups (293 +/- 22 and 311 +/- 22 pM for trained and sedentary, respectively). Insulin-mediated glucose disposal rates (GDR) were greater (P < 0.05) in the exercise-trained compared with the sedentary control group (9.22 +/- 0.95 vs. 6.36 +/- 0.57 mg. kg fat-free mass(-1). min(-1)). Insulin-stimulated PI3-kinase activation was also greater (P < 0.004) in the trained compared with the sedentary group (3.8 +/- 0.5- vs. 1.8 +/- 0.2-fold increase from basal). Endurance capacity (VO(2 max)) was positively correlated with PI3-kinase activation (r = 0.53, P < 0.04). There was no correlation between PI3-kinase and muscle morphology. However, increases in GDR were positively related to PI3-kinase activation (r = 0.60, P < 0.02). We conclude that regular exercise leads to greater insulin-stimulated IRS-1-associated PI3-kinase activation in human skeletal muscle, thus facilitating enhanced insulin-mediated glucose uptake.

CNS acetylcholine receptor activity in European medicinal plants traditionally used to improve failing memory

Certain Lamiaceous and Asteraceous plants have long histories of use as restoratives of lost or declining cognitive functions in western European systems of traditional medicine. Investigations were carried out to evaluate human CNS cholinergic receptor binding activity in extracts of those European medicinal plants reputed to enhance or restore mental functions including memory. Ethanolic extracts were prepared from accessions of these plants and a number of other species related by genus. Amongst the plant extracts screened for contents able to displace [3H]-(N)-nicotine and [3H]-(N)-scopolamine from nicotinic receptors and muscarinic receptors, respectively in homogenates of human cerebral cortical cell membranes, the most potent extracts, prepared from one accession of Melissa officinalis, three Salvia species and Artemisia absinthium had IC50 concentrations of < 1 mg/ml. The displacement curves of some extracts were comparable with that of carbamylcholine chloride, a potent acetylcholine analogue. Choline, a weak nicotinic ligand (IC50 = 3 x 10(-4) M) was found in extracts of all plants studied at concentrations of 10(-6)-10(-5) M. These concentrations could not account for not more than 5% of the displacement activity observed. Some extracts displayed differential displacement at nicotinic and muscarinic acetylcholine receptors, with M. officinalis 0033 having the highest [3H]-(N)-nicotine displacement value and Salvia elegans with the highest [3H]-(N)-scopolamine displacement value. There was also considerable variation in cholinoreceptor interactions between different accessions of a single plant species. Although most plant extracts screened showed some nicotinic and muscarinic activity, only some showed dose-dependent receptor activity typical of materials with genuine cholinergic activity.

Telemedicine versus face to face patient care: effects on professional practice and health care outcomes

BACKGROUND

Telemedicine is the use of telecommunications technology for medical diagnosis and patient care. From its beginnings telemedicine has been used in a variety of health care fields, although widespread interest among healthcare providers has only now become apparent with the development of more sophisticated technology.

OBJECTIVES

To assess the effects of telemedicine as an alternative to face-to-face patient care.

SEARCH STRATEGY

We searched the Effective Practice and Organisation of Care Group's specialised register, The Cochrane Library, MEDLINE (1966-August 1999), EMBASE (to 1996), Cinahl (to August 1999), Inspec (to August 1996), Healthstar (1983-1996), OCLC, Sigle (to 1999), Assia, SCI (1981-1997), SSCI (1981-1997), DHSS-Data. We hand searched the Journal of Telemedicine and Telecare (1995-1999), Telemedicine Journal (1995-1999) and reference lists of articles. We also hand searched conference proceedings and contacted experts in countries identified as having an interest in telemedicine.

SELECTION CRITERIA

Randomised trials, controlled before and after studies and interrupted time series comparing telemedicine with face-to-face patient care. The participants were qualified health professionals and patients receiving care through telemedicine.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data.

MAIN RESULTS

Seven trials involving more than 800 people were included. One trial was concerned with telemedicine in the emergency department, one with video-consultations between primary health care and the hospital outpatients department, and the remainder were concerned with the provision of home care or patient self-monitoring of chronic disease. The studies appeared to be well conducted, although patient numbers were small in all but one. Although none of the studies showed any detrimental effects from the interventions, neither did they show unequivocal benefits and the findings did not constitute evidence of the safety of telemedicine. None of the studies included formal economic analysis. All the technological aspects of the interventions appear to have been reliable, and to have been well accepted by patients.

REVIEWER'S CONCLUSIONS

Establishing systems for patient care using telecommunications technologies is feasible, but there is little evidence of clinical benefits. The studies provided variable and inconclusive results for other outcomes such as psychological measures, and no analysable data about the cost effectiveness of telemedicine systems. The review demonstrates the need for further research and the fact that it is feasible to carry out randomised trials of telemedicine applications. Policy makers should be cautious about recommending increased use and investment in unevaluated technologies.

Sertindole for schizophrenia

BACKGROUND

Sertindole is an atypical antipsychotic, which is thought to give a lower incidence of extrapyramidal side effects at clinically effective doses than typical antipsychotic drugs. In December 1998, Lundbeck Ltd., the manufacturers of sertindole, voluntarily suspended the availability of the drug due to concerns about cardiac arrhythmia and sudden cardiac death associated with its use. Sertindole has therefore been withdrawn from the market pending discussion with the European Regulatory Authority over cardiac safety.

OBJECTIVES

To determine the effects of sertindole compared with placebo, typical and other atypical antipsychotic drugs for schizophrenia and related psychoses.

SEARCH STRATEGY

Electronic searches of Biological Abstracts (1980-1999), The Cochrane Library (Issue 1, 1999), The Cochrane Schizophrenia Group's Register (January 1999), EMBASE (1980-1999), LILACS (1982-1996), MEDLINE (1966-1999), PSYNDEX (1977-1995) and PsycLIT (1974-1999) were undertaken. In addition, pharmaceutical databases on the Dialog Corporation Datastar and Dialog services were searched. References of all identified studies were searched for further trials. The manufacturer of sertindole and authors of trials were contacted.

SELECTION CRITERIA

All randomised controlled trials that compared sertindole to placebo or other antipsychotic drug treatments were included by independent assessment.

DATA COLLECTION AND ANALYSIS

Citations and, where possible, abstracts were independently inspected by reviewers, papers ordered, re-inspected and quality assessed. Data were independently extracted. For homogeneous dichotomous data the risk ratio (RR), 95% confidence interval (CI) and, where appropriate, the number needed to treat (NNT) or numbers needed to harm (NNH) were calculated on an intention-to-treat basis. For continuous data, weighted mean differences (WMD) were calculated. All data were inspected for heterogeneity.

MAIN RESULTS

Two large important studies were excluded, because they did not report any usable data. The two that were included suggested that sertindole was more antipsychotic than placebo, as acceptable as placebo and better tolerated than haloperidol (NNT=9, RR 0.63 CI 0.41 to 0.96). Sertindole was associated with fewer movement disorders than haloperidol but was shown to cause more weight gain (NNH=9 RR 6.33, CI 1.92 to 20.92), rhinitis (NNH=8, RR 1.74, CI 1,28 to 2.36) and possibly male sexual dysfunction. Cardiac problems (QTc intervals of at least 500msec) were evident even in the randomised trials (NNH=13 RR 23, CI 1.37 to 386.60).

REVIEWER'S CONCLUSIONS

Because of the cardiac problems, even evident within poorly reported studies, at present sertindole should, if possible, be avoided. If sertindole is to be reintroduced, gold-standard evidence of its clinical benefits will need to far outweigh its real risks.

Diabetic emergencies: Part 2. Hyperglycaemia

Part 2 of this series explores the pathophysiology and clinical management of diabetic emergencies involving hyperglycaemia, including both diabetic ketoacidosis and the rarer hypernatremic, non-ketotic coma. Part 1 (Hypoglycaemia) was published in Accident and Emergency Nursing 7(4): 190-196.

Molindone for schizophrenia and severe mental illness

BACKGROUND

Typical antipsychotic drugs are widely used as the first line treatment for people with schizophrenia. However, the atypical class of antipsychotic drugs is making important inroads into this approach. 'Atypical' is a term widely used to describe some antipsychotics which have a low propensity to produce movement disorders, sedation and raised serum prolactin. There is some suggestion that the different adverse effect profiles of the atypical antipsychotic group make them more acceptable to people with schizophrenia. Molindone has a similar profile to quetiapine (a novel atypical antipsychotic), with very low binding to all receptors. Some authors have suggested that molindone is safer than other 'typical' antipsychotics in that extrapyramidal adverse effects are not usually seen at clinically effective antipsychotic doses and that it should therefore be classed as an atypical antipsychotic.

OBJECTIVES

To determine the effects of molindone compared with placebo, typical and other atypical antipsychotic drugs for schizophrenia and related psychoses.

SEARCH STRATEGY

Electronic searches of Biological Abstracts (1980-1999), The Cochrane Library CENTRAL (Issue 1, 1999), The Cochrane Schizophrenia Group's Register (January 1999), CINAHL (1982-1999), EMBASE (1980-1999), MEDLINE (1966-1999), LILACS (1982-1999), PSYNDEX (1977-1999), and PsycLIT (1974-1999) were undertaken. In addition, pharmaceutical databases on the Dialog Corporation Datastar and Dialog services were searched. References of all identified studies were searched for further trials. The manufacturer of molindone and authors of trials were contacted.

SELECTION CRITERIA

All randomised controlled trials that compared molindone to other treatments for schizophrenia and schizophrenia-like psychoses were included by independent assessment.

DATA COLLECTION AND ANALYSIS

Citations and, where possible, abstracts were independently inspected by reviewers, papers ordered, re-inspected and quality assessed. Data were independently extracted. Data were excluded if loss to follow up was greater than 50%. For homogeneous dichotomous data the risk ratio (RR), 95% confidence interval (CI) and, where appropriate, the number needed to treat (NNT) were calculated on an intention-to-treat basis. For continuous data, weighted mean differences (WMD) were calculated. All data were inspected for heterogeneity.

MAIN RESULTS

Thirteen studies were included in the review. Data for this compound range from very short (10 day) studies of the intramuscular preparation to trials lasting over three months. For measures of global state available data do not justify any conclusions on the comparative efficacy of molindone and placebo. When compared to other typical antipsychotics no difference in effectiveness was evidenced (doctors' RR 1.13, CI 0.69 to 1.86; nurses' RR 1.23, CI 0.82 to 1.86). It is no more or less likely than typical drugs to cause movement disorders, but causes significantly more weight loss (RR 2.78, CI 1.10 to 6.99).

REVIEWER'S CONCLUSIONS

The strength of the evidence relating to this compound is limited, owing to small sample size, poor study design, limited outcomes and incomplete reporting. Molindone may be an effective antipsychotic; however, its adverse effect profile does not differ significantly from that of typical antipsychotics, apart from the event of weight loss. At present there is no evidence to suggest that it may have an atypical profile.

Who contracts for primary care?

The implications of the 1997 NHS (Primary Care) Act have been largely overlooked in the rush to establish Primary Care Groups. Allowing health authorities to develop local contracts for primary care has far-reaching implications and is an important departure from the national system of negotiation that has characterized general practice to date. This paper describes a content analysis of a sample of Personal Medical Services (PMS) pilot contracts. In the first year little attention has been given to achieving cost savings or greater efficiency and few contracts promote clinical guidelines. The difficulties of specifying services sensitive to local health needs are highlighted and the national Statement of Fees and Allowances (the 'Red Book') may not be swiftly supplanted. However, the pilots have introduced innovations such as salaried general practitioners, nurse-led services and NHS trust-managed care. The development of local contracts provides a valuable learning experience for general practitioners and health authorities in advance of the establishment of Primary Care Trusts.

Primary care. Communal living

From this month, 80 per cent of health authorities will have at least one personal medical services pilot scheme in their area. The extension of the schemes raises concerns about equity and management issues for HAs. An HA where schemes will cover almost a third of the population has had to adopt an off-the-peg approach to development.

The Effect of Gibberellins on Flowering in Roses

The gibberellins A(1), A(3), A(5), A(8), A(19), A(20), and A(29) were identified in vegetative shoot tips of Rosa canina by comparing their mass spectra and Kovats retention indices with those of standards. Most wild roses have a short flowering season of 2-4 weeks in spring, whereas most modern cultivars flower recurrently. 'Félicité et Perpétue' is a short-season hybrid from a cross between a wild rose and a recurrent-flowering rose, whereas its sport, 'Little White Pet,' flowers recurrently. The concentrations of gibberellins (GAs) were measured in shoot apices of both cultivars. In March (before floral initiation in spring) the concentrations of GA(1) and GA(3) were respectively threefold and twofold higher in 'Félicité et Perpétue' than in 'Little White Pet.' In April (after floral initiation) the concentrations of both gibberellins were substantially greater than in March, and concentrations of GA(1) and GA(3) were, respectively, 17-fold and 12-fold greater in 'Félicité et Perpétue' than in 'Little White Pet.' It is postulated that, in 'Félicité et Perpétue,' floral initiation occurs when concentrations of GAs are low and is inhibited when concentrations of GAs are high, whereas in 'Little White Pet' concentrations of GAs remain at permissive levels throughout the growing season. Applications of GA(1) and GA(3) to axillary shoots in March inhibited floral development in 'Félicité et Perpétue' but not in 'Little White Pet.' This suggests that the combined concentration of exogenous and endogenous gibberellins might have been raised to inhibitory levels in the former but not in the latter cultivar.

Comparison of in-vitro pharmacodynamics of once and twice daily ciprofloxacin

The pharmacodynamics of ciprofloxacin were explored in an in-vitro continuous bacterial culture model of infection, by simulating two oral dosing regimens; 0.5 g 12-hourly (bd) and 1 g 24-hourly (od). Three strains of Escherichia coli (ciprofloxacin MICs 0.03, 0.5 and 2 mg/L); two strains of Pseudomonas aeruginosa (MICs 0.09 and 1.5 mg/L), two strains of Staphylococcus aureus (MICs 0.12 and 1 mg/L) and two strains of Streptococcus pneumoniae (MICs 0.5 and 2 mg/L) were used. Three pharmacodynamic parameters, T > MIC, C(max)/MIC and AUC/MIC (T = time, C(max) = peak serum concentration, AUC = area under the curve), were compared with area under the bacterial-kill curve (AUBKC) (after transformation of the AUBKC) using a simple E(max) or sigmoidal E(max) model. AUBKC was taken to be the main antibacterial effect measure. The models were compared by inspection of residuals and Akaike information criterion. E(max) models adequately described the relationship between AUC/MIC and AUBKC and between C(max)/MIC and AUBKC, but not between T> MIC and AUBKC. All three pharmacodynamic parameters are related to each other but multiple regression analysis indicated that AUC/MIC was the best individual predictor of AUBKC. Despite this, comparison of od and bd regimens indicates some advantage to od in terms of early antibacterial effect. Serum concentration-time curve shape has some importance in determining antibacterial effect. These data indicate that for ciprofloxacin AUC/MIC ratio is not the sole determinant of antibacterial effect.

Chronic treatment with finasteride daily does not affect spermatogenesis or semen production in young men

PURPOSE

Finasteride, an oral type 2, 5alpha-reductase inhibitor, is used in 1 mg. daily doses for the treatment of male pattern hair loss. A dose of 5 mg. finasteride daily reduces ejaculate volume by approximately 25%, and reduces prostate volume by approximately 20% and serum prostate specific antigen (PSA) by approximately 50% in men with benign prostatic hyperplasia. To our knowledge no data exist on the effect of 1 mg. finasteride daily on ejaculate volume or other semen parameters, or on the prostate in young men. Therefore, we studied the potential effect and reversibility of effect of 1 mg. finasteride daily on spermatogenesis, semen production, the prostate and serum PSA in young men.

MATERIALS AND METHODS

In this double-blind, placebo controlled multicenter study 181 men 19 to 41 years old were randomized to receive 1 mg. finasteride or placebo for 48 weeks followed by a 60-week off-drug period. Of the 181 men 79 were included in a subset for the collection and analysis of sequential semen samples.

RESULTS

There were no significant effects of 1 mg. finasteride on sperm concentration, total sperm per ejaculate, sperm motility or morphology. Ejaculate volume in subjects on finasteride decreased 0.3 ml. (-11%) compared to a decrease of 0.2 ml. (-8%) for placebo, with a median between treatment group difference of -0.03 ml. (1%, 90% confidence interval -10.4 to 13.1, p = 0.915). There were significant but small decreases in prostate volume (-2.6%) and serum PSA (-0.2 ng./ml.) in the finasteride group, which reversed on discontinuation of the drug.

CONCLUSIONS

Treatment with 1 mg. finasteride daily for 48 weeks did not affect spermatogenesis or semen production in young men. The effects of 1 mg. finasteride daily on prostate volume and serum PSA in young men without benign prostatic hyperplasia were small and reversible on discontinuation of the drug.

Diabetic emergencies: Part 1. Hypoglycaemia

Diabetes mellitus is a chronic, lifelong condition which can affect people of all ages, and is increasing in prevalence. Hypoglycaemia is probably the most common acute problem suffered by patients with diabetes. It is also a serious medical emergency with potentially fatal outcomes, and is the most common reason for patients with diabetes attending an accident and emergency (A&E) department. It is also a major source of anxiety for diabetics, particularly those controlled on insulin, and unfortunately, in the move towards ever tighter glycaemic control, it is inevitable that diabetics will continue to suffer from hypoglycaemia. This article examines the pathophysiology of hypoglycaemia and some of its main causes, and will look at the clinical management of the patient with hypoglycaemia, both in the community and in the A&E department. The importance of the recognition and prompt treatment of hypoglycaemia, and of the investigation of hypoglycaemia with no obvious cause are also discussed. Part 2 of the series will explore the pathophysiology and clinical management of diabetic emergencies involving hyperglycaemia, including both diabetic ketoacidosis and the rarer hypernatremic, non-ketotic coma.

Health issues in plastics production and processing

Plastic components are essential in countless applications. Plastics can be molded into virtually any shape or size and also formed into sheets, coatings, or laminates. Plastic materials may have equal strength, durability, and impact resistance as metals, yet they are often much lighter, a distinct advantage in the automobile industry. With different combinations of polymers and additives, the production of materials with unique properties and applications is seemingly limitless. Given the size and diversity of plastics-related employment, occupational health professionals are likely to be involved in assessing health issues related to plastic manufacturing and processing. As industrial and medical experience with these compounds has grown, so has the recognition of a variety of potential health hazards. Health professionals need to be familiar with the different sectors of this industry and the diverse materials and processes.

Overview of the rubber industry and tire manufacturing

The production of rubber and rubber products is a large and diverse industry. Natural rubber, obtained from plantations in Africa and Asia, accounts for only about 25% of the rubber used in industry. Synthetic alternatives, developed during World War II, are the primary sources of raw materials today. Health hazards in synthetic rubber production are primary related to exposure to monomers. An excess incidence of leukemia has been observed in styrene/butadiene rubber production, attributed to exposure to 1,3-butadiene. Excesses of cancer and respiratory disease have been reported, although specific causative agents are rarely identified. Exposures have varied greatly over the years, based on changes in materials used, work practices, and ventilation. In modern industry, exposures to noise, skin and respiratory irritants, and ergonomic stressors remain important. The tire industry, in particular, has been studied extensively over the past 50 years.

Vinyl chloride and polyvinyl chloride

Polyvinyl chloride (PVC) is an important plastic resin for construction, pipe and tubing, siding, and other uses. Exposures to vinyl chloride monomer during the early years of production resulted in an important sentinel health event: the recognition of an excess of a rare liver cancer, hepatic angiosarcoma, at facilities throughout the world. Several other syndromes, including acro-osteolysis, also have been associated with PVC, but less clearly with vinyl chloride. Extensive research ranging from large-scale epidemiologic studies to biomarker research into molecular mechanisms continues to provide valuable insight into the pathogenesis of occupational cancer.

Peripheral neuropathy caused by proteolipid protein gene mutations

Pelizaeus-Merzbacher disease (PMD) is a dysmyelinating disorder of the central nervous system typically caused by duplications or missense mutations of the proteolipid protein (PLP) gene. Most investigators have found that peripheral nerve function and structure is normal in PMD patients. We have found that null mutations of the PLP gene cause demyelinating peripheral neuropathy, whereas duplications and a proline 14 to leucine mutation do not affect nerve function. A family with a nonsense mutation at position 144, which affects only PLP but not the alternatively spliced gene product DM20, has a very mild syndrome, including normal peripheral nerve function. Our findings suggest that DM20 alone is sufficient to maintain normal nerve function and that there may be domains of PLP/DM20 that have a relatively more active role in the peripheral nervous system compared with that in the central nervous system.

Correlation between weakness and axonal loss in patients with CMT1A

We have developed a protocol to measure the progression of disability in patients with Charcot Marie Tooth (CMT) disease, particularly CMT1 over a several year period. Because CMT1 is a chronic disease, the natural history of changes occurring in such a brief period are not well understood, making clinical trials for CMT1 patients difficult to evaluate. We hypothesize that weakness in CMT1 correlates with axonal loss secondary to the abnormalities in Schwann cell myelin gene expression, which cause the disease. To test this hypothesis, we elected to carefully evaluate CMT patients by various modalities to measure strength, sensory loss, and axonal loss and demyelination and to compare these modalities to determine whether they correlated with findings on clinical examination. As suspected, patient weakness correlates more with secondary axonal loss than with demyelination, even though the primary abnormality in CMT1 is demyelination.

Famine in southern Sudan

We provide baseline information and objective testimony on severe malnutrition and high mortality in the general population of southern Sudan that is affected by chronic civil war and severe famine.

Comparison of two regimens of beta-adrenergics in acute asthma

BACKGROUND AND METHODS

Inhaled adrenergics and steroids are the main agents used in acute asthma. Dosing recommendations for adrenergics, while generally becoming more aggressive, lack prospective validation. A double blind, randomized trial of two regimens of nebulized metaproterenol was conducted in patients presenting to an Emergency Department with an acute asthma exacerbation. Asthmatics age 16-55, with no other cardio-pulmonary disease, presenting with peak expiratory flow rate (PEFR) < 30% of predicted and greater than 80 L/m were enrolled. All patients received 125 mg of methylprednisolone and theophylline, if needed, to reach therapeutic levels. The experimental group received 0.3 cc metaproterenol in 2.5 cc of saline at times 0, 20", 40", 1', 2', 3', 4', 5', 6', and 7'. The control group received metaproterenol at times 0, 1 hr, and hours 3, 5, and 7. Placebo was given to control group patients at 20", 40", 2', 4', and 6'. PEFR and vital signs were measured 10 min after each treatment. Study end points included discharge upon reaching set criteria or admission if patients were not discharged following the hour 7 treatment.

RESULTS

Seventy one patients were enrolled, 40 in experimental group and 31 in the control group. The group characteristics did not differ at entry in any significant way, and the groups began with mean expected PEFR of 23.4% and 24.5%, respectively. There were no significant differences at any point in PEFR outcomes, time to discharge, or admission rate. The experimental group showed a greater increase in pulse rate and a reduced diastolic blood pressure at 20, 40 and 60 min. The experimental group had a 12- and 8-fold increase in the risk of a pulse rate > 140 at 40 and 60 min, respectively. This group also had two moderate complications, both near the 60-minute mark. These were an induction of atrial fibrillation in one patient and ischemic electrocardiographic changes in another.

CONCLUSION

Three treatments in the first hour, and hourly thereafter showed no benefit over treatments initially, at one hour, and every other hour in acute, moderate, or severe exacerbation of asthma. Side effects were markedly increased in the control group. Such dosing should not be recommended as routine therapy.

Positionally selective growth of embryonic spinal cord neurites on muscle membranes

Motor neurons from distinct positions along the rostrocaudal axis generally innervate muscles or muscle fibers from corresponding axial levels. These topographic maps of connectivity are partially restored after denervation or transplantation under conditions in which factors of timing and proximity are eliminated. It is therefore likely that motor neurons and some intramuscular structures bear cues that bias synapse formation in favor of positionally matched partners. To localize these cues, we studied outgrowth of neurites from embryonic spinal cord explants on carpets of membranes isolated from perinatal rat muscles. Neurites from rostral (cervical) and caudal (lumbar) spinal cord slices exhibit distinct growth preferences. In many instances, rostrally derived neurites grew selectively on membranes from forelimb muscles or from a single thoracic muscle (the serratus anterior) when given a choice between these membranes and membranes from hindlimb muscles or laminin. Caudally derived neurites almost never exhibited such rostral preferences, but instead preferred membranes from hindlimb muscles or a single hindlimb muscle (the gluteus) to rostral muscles or laminin. Likewise, spinal neurites exhibited distinct position-related preferences for outgrowth on membranes of clonal myogenic cell lines derived from specific rostral and caudal muscles. Taken together these results suggest that the membranes of motor axons and myotubes bear complementary labels that vary with rostrocaudal position and regulate neuromuscular connectivity.

Use of a clinical Escherichia coli isolate expressing lux genes to study the antimicrobial pharmacodynamics of moxifloxacin

Escherichia coli isolate 16,906 expressing lux genes was used for real-time monitoring of moxifloxacin effects on bacterial metabolism compared with effects on cell replication. Viable counts showed concentration-dependent killing by moxifloxacin; real-time measurement of bioluminescence on the same cultures showed metabolic activity over 54 h, but with greater inhibition at 1 x MIC than with higher MIC multiples. Post-antibiotic effect was longer when determined using bioluminescence than by viable counts. The control-related effective regrowth time was consistent with both methods. Bioluminescent bacteria provide a rapid and sensitive means for measuring antimicrobial effects on bacterial metabolism.

Effects of castration and testosterone replacement on veno-occlusion during penile erection in the rat

AIM

To determine if androgens directly regulate veno-occlusion or if androgens act indirectly to maintain the penile structures which control outflow.

METHODS

Using CASTRATE and TESTO rats, measurement was made of mean arterial pressure (MAP), intracavernosal pressure (CCP), and intracavernosal flow (CCF) during erection resulting from stimulation of the autonomic innervation of the penis. CCP and CCF were also measured during saline infusion into the cavernosal sinuses before and after treatment with sodium nitroprusside (SNP, a nitric oxide donor drug) to fully relax cavernosal smooth muscle. Penile tissue was also collected to measure the content of alpha actin and proline and hydroxyproline to determine if brief withdrawal of androgenic support led to changes in the number of smooth muscle cells or the collagen content of the tissue.

RESULTS

Infusion of saline into the cavernosal sinuses demonstrated that veno-occlusion was defective in CASTRATE rats while veno-occlusion was fully functional in TESTO animals. Furthermore, veno-occlusion could be induced in CASTRATE rats if they were first treated with SNP. This observation suggests that failure of veno-occlusion in the CASTRATE rats is due to a deficiency in the production of NO resulting in a reduction in the degree of relaxation of the penile smooth muscle. The measurements of smooth muscle a actin and proline and hydroxyproline content of collagen showed that both were unaffected by castration and that the basic structure of the penis did not degenerate after one week without androgenic support.

CONCLUSION

These results can be interpreted to mean that androgens control the veno-occlusive mechanism indirectly via a NO dependent mechanism and not by maintaining the structures of the penis which are essential to veno-occlusion.

Orbscan pachymetry: implications of a repeated measures and diurnal variation analysis

INTRODUCTION

Corneal thickness changes reflect alterations in hydration and metabolism. Ultrasound pachymetry determinations may be adversely influenced by fluctuations in tissue hydration, whereas optical systems are apparently unaffected by these fluxes. A recently marketed, optical-based, topographic mapping system (Orbscan; Orbtek, Inc.) uses anterior and posterior corneal surface data to calculate corneal thickness.

OBJECTIVE

This new instrumentation presents as a potentially useful pachymetry tool for evaluation of corneas under hydration flux or challenge (e.g., postphotorefractive keratectomy [PRK] healing studies) and was therefore evaluated for accuracy and variability.

MEASUREMENTS

Three calibrated standards were measured in repeated fashion. Additionally, 1 test subject was measured 30 times in 1 day (5 measurements each at 8:00, 9:30, and 11:00 AM and at 1:00, 2:30, and 4:00 PM). Corresponding measurements were made at 8:00 and 11:00 AM and at 4:00 PM on 3 separate days to assess repeatability. Grouped data from 18 volunteer subjects were compared to the data of the test subject as well.

RESULTS

Pachymetry accuracy on a calibrated standard was determined to be +/-2 microm (standard deviation, n = 12). Repeated measures on the subject demonstrated a mean standard deviation of 9.08 microm for 750 thickness data points across the central 7 mm of the cornea; peripheral measurement points exhibited progressively greater variability than at the apex (analysis of variance; P<0.0001). A plot of thickness by corneal location and time of day exhibited a diurnal pattern, with the peripheral cornea exhibiting progressively greater thickness changes than the central cornea (two-way analysis of variance; P<0.00001). The data significantly correlated across days when all times of day were considered (r = 0.999). However, thickness values obtained at 8:00 AM were significantly different across days (t test; P<0.0002). The subject's data correlated very well (r = 0.9996) with the grouped volunteer data.

CONCLUSIONS

These data show this system to be useful in corneal research and in clinical settings. The data confirm early morning pachymetry to be highly variable. Additionally, the data not only indicate a diurnal variation of corneal hydration over time, but also imply the presence of a diurnal-based hydration gradient across the peripheral cornea, both of which can have significance for PRK, since excimer tissue ablation effectiveness is influenced by tissue hydration.

Analysis of potential phosphorylation sites in human T cell leukemia virus type 1 Tax

The human T cell leukemia virus type 1 (HTLV-1) Tax is a phosphoprotein, however, the contribution of phosphorylation to Tax activity is unknown. Previous studies have shown that phosphorylation of Tax occurs on serine residue(s), within one tryptic fragment, in response to 4beta-phorbol-12beta-myristate-13alpha-acetate, in both mouse and human cells. Studies were conducted in multiple cell lines to identify the specific phosphorylated serines as a prelude to functional analysis. The phosphorylation pattern of Tax was found to be different in 293T and COS-7 cells in comparison with MT-4 and Px-1 cells. However, one tryptic fragment remained consistent in comigration analyses among all cell lines. Using selected Tax serine mutants a tryptic fragment containing a serine at residue 113 believed to be the site of phosphorylation of Tax did not comigrate with the common phosphorylated tryptic fragment. Analysis of selected Tax mutants for ability to trans-activate the cytomegalovirus promoter demonstrated mutation of serine 77 to alanine reduced trans-activation by 90% compared to wild-type Tax. However, examination of the phosphorylation pattern of the serine 77 mutant demonstrated that it is not the site of phosphorylation. These studies demonstrate the importance of using relevant cell lines to characterize the role of phosphorylation in protein function.

Synthesis, pharmacological characterization, and molecular modeling of heterobicyclic amino acids related to (+)-2-aminobicyclo[3.1.0] hexane-2,6-dicarboxylic acid (LY354740): identification of two new potent, selective, and systemically active agonists for group II metabotropic glutamate receptors

As part of our ongoing research program aimed at the identification of highly potent, selective, and systemically active agonists for group II metabotropic glutamate (mGlu) receptors, we have prepared novel heterobicyclic amino acids (-)-2-oxa-4-aminobicyclo[3.1. 0]hexane-4,6-dicarboxylate (LY379268, (-)-9) and (-)-2-thia-4-aminobicyclo[3.1.0]hexane-4,6-dicarboxylate (LY389795, (-)-10). Compounds (-)-9 and (-)-10 are structurally related to our previously described nanomolar potency group II mGlu receptor agonist, (+)-2-aminobicyclo[3.1.0]hexane-2,6-dicarboxylate monohydrate (LY354740 monohydrate, 5), with the C4-methylene unit of 5 being replaced with either an oxygen atom (as in (-)-9) or a sulfur atom (as in (-)-10). Compounds (-)-9 and (-)-10 potently and stereospecifically displaced specific binding of the mGlu2/3 receptor antagonist ([3H]LY341495) in rat cerebral cortical homogenates, displaying IC50 values of 15 +/- 4 and 8.4 +/- 0.8 nM, respectively, while having no effect up to 100 000 nM on radioligand binding to the glutamate recognition site on NMDA, AMPA, or kainate receptors. Compounds (-)-9 and (-)-10 also potently displaced [3H]LY341495 binding from membranes expressing recombinant human group II mGlu receptor subtypes: (-)-9, Ki = 14.1 +/- 1.4 nM at mGlu2 and 5.8 +/- 0.64 nM at mGlu3; (-)-10, Ki = 40.6 +/- 3.7 nM at mGlu2 and 4.7 +/- 1.2 nM at mGlu3. Evaluation of the functional effects of (-)-9 and (-)-10 on second-messenger responses in nonneuronal cells expressing human mGlu receptor subtypes demonstrated each to be a highly potent agonist for group II mGlu receptors: (-)-9, EC50 = 2.69 +/- 0.26 nM at mGlu2 and 4.58 +/- 0.04 nM at mGlu3; (-)-10, EC50 = 3.91 +/- 0.81 nM at mGlu2 and 7.63 +/- 2. 08 nM at mGlu3. In contrast, neither compound (up to 10 000 nM) displayed either agonist or antagonist activity in cells expressing recombinant human mGlu1a, mGlu5a, mGlu4a, or mGlu7a receptors. The agonist effects of (-)-9 and (-)-10 at group II mGlu receptors were not totally specific, however, as mGlu6 agonist activity was observed at high nanomolar concentrations for (-)-9 (EC50 = 401 +/- 46 nM) and at micromolar concentrations (EC50 = 2 430 +/- 600 nM) for (-)-10; furthermore, each activated mGlu8 receptors at micromolar concentrations (EC50 = 1 690 +/- 130 and 7 340 +/- 2 720 nM, respectively). Intraperitoneal administration of either (-)-9 or (-)-10 in the mouse resulted in a dose-related blockade of limbic seizure activity produced by the nonselective group I/group II mGluR agonist (1S,3R)-ACPD ((-)-9 ED50 = 19 mg/kg, (-)-10 ED50 = 14 mg/kg), indicating that these molecules effectively cross the blood-brain barrier following systemic administration and suppress group I mGluR-mediated limbic excitation. Thus, heterobicyclic amino acids (-)-9 and (-)-10 are novel pharmacological tools useful for exploring the functions of mGlu receptors in vitro and in vivo.

Non-ginsenoside nicotinic activity in ginseng species

Amongst the many different therapeutic applications of ginseng are beneficial effects on age-related cognitive impairments. Ageing in the brain is associated with a loss of nicotinic receptor binding and receptor stimulation increases binding. Stimulation of the CNS (central nervous system) nicotinic receptor is considered to be beneficial in relation to symptomatic treatment and neuroprotection in age-associated cognitive disorders which involve a further receptor loss. We assessed Panax ginseng, Panax quinquefolium and several chemical constituents of these plants for nicotinic activity based on displacement of 3H-(-)nicotine from human brain cerebral cortex membranes in vitro. Dose-dependent displacement was evident in crude ethanol extracts of Panax ginseng and Panax quinquefolium. Assay of an extract of Panax ginseng showed the plant to have affinity for both the nicotinic receptor, and to a lesser extent the muscarinic receptor (IC50 2.12 mg/mL and 5.25 mg/mL respectively). Activity was largely conserved after the extraction of choline and other water soluble quaternary ammonium compounds (QAC), indicating that the activity of the plant extracts was not due to choline. Displacement binding assay of some purified chemical constituents, including a number of ginsenosides, showed that these were not primarily responsible for Panax activity. The active chemical constituent has yet to be identified, but the demonstrated nicotinic activity of ginseng warrants further investigation with reference to therapeutic activity in age-related conditions such as dementia.