Implementing E-MOTIVE for detection and treatment of postpartum haemorrhage in South Africa

Postpartum haemorrhage is the leading cause of preventable maternal mortality in South Africa. In a significant breakthrough in the management of PPH, the E-MOTIVE trial found that a multifaceted health service intervention reduced severe PPH after vaginal delivery by 60% in 78 hospitals in Nigeria, Kenya, Tanzania and SA. The E-MOTIVE approach comprises objective blood loss measurement monitored every 15 minutes during the first hour after delivery to detect PPH early and trigger a bundle of first-line treatments, including massaging the uterus, oxytocin infusion, tranexamic acid infusion, intravenous crystalloid fluids, examination for the cause, emptying the bladder and, if necessary, escalation of care. E-MOTIVE was integrated into the existing Essential Steps in Managing Obstetric Emergencies algorithm. Certain research-related elements of the trial setting cannot be replicated in routine practice. Therefore, we need to develop local strategies to ensure the essential clinical elements of the intervention are implemented. Potential strategies include incorporating the E-MOTIVE principles into national guidelines, ongoing training strategies and ensuring all facilities are equipped with necessary medication, equipment and delegations. This breakthrough intervention provides hope for women in SA, and requires a purposeful, co-ordinated implementation strategy on a national scale to reach all levels of the health service.

073 Posterior reversible encephalopathy syndrome (PRES) complicating anti-NMDA receptor encephalitis (NMDARE) with ovarian teratoma

Introduction

Anti-N-methyl-D-aspartate receptor antibody-associated encephalitis (NMDARE) is a form of autoimmune encephalitis typically affecting young women, often associated with an ovarian teratoma. Clinical features include psychiatric disturbances, seizures, dyskinesia, dysautonomia, and cardiac dys- rhythmias. Here we present a case of NMDARE complicated by posterior reversible encephalopathy syndrome (PRES). This complication has not been reported previously.

Case

A 17-year-old girl presented with acute psychosis. The neurological examination was unremark- able. MRI brain revealed left hippocampal T2 signal hyperintensity; there was a CSF lymphocytosis. NMDA-receptor antibodies in serum and CSF were detected and intravenous methylprednisolone was commenced. Progressive agitation lead to ITU admission. Plasma exchange and intravenous immuno- globulins were administered. MRI pelvis revealed a left ovarian cyst which was removed (laparoscopic salpingo-oophrectomy). Gross inspection and histopathology confirmed an ovarian teratoma. Persistently elevated blood pressure was noted for a week on ITU, associated with clinical deterioration. Rituximab was administered. A repeat MRI brain the next day revealed hyperintensities in temporo-parietal and occipital regions consistent with PRES. The second dose of rituximab was withheld. Clinical and radiologi- cal improvement was noted after a week, and the patient was discharged home.

Discussion

Encephalitis mediated dysautonomia may lead to disruption of cerebral autoregulation cul- minating in PRES. The administration of rituximab may also have contributed. This case exemplifies the uncommon complications associated with NMDARE.

dr.dvinayan@gmail.com

Cortical myoclonus and epilepsy in a family with a new SLC20A2 mutation

Idiopathic basal ganglia calcification (IBGC) or primary familial brain calcification is a rare genetic condition characterized by an autosomal dominant inheritance pattern and the presence of bilateral calcifications in the basal ganglia, thalami, cerebellum and cerebral subcortical white matter. The syndrome is genetically and phenotypically heterogeneous. Causal mutations have been identified in four genes: SLC20A2, PDGFRB, PDGFB and XPR1. A variety of progressive neurological and psychiatric symptoms have been described, including cognitive impairment, movement disorders, bipolar disorder, chronic headaches and migraine, and epilepsy. Here we describe a family with a novel SLC20A2 mutation mainly presenting with neurological symptoms including cortical myoclonus and epilepsy. While epilepsy, although rare, has been reported in patients with IBGC associated with SLC20A2 mutations, cortical myoclonus seems to be a new manifestation.

Relationship between 'on-treatment platelet reactivity', shear stress, and micro-embolic signals in asymptomatic and symptomatic carotid stenosis

BACKGROUND

Assessment of 'high on-treatment platelet reactivity (HTPR)' could enhance understanding of the pathophysiology of first or recurrent vascular events in carotid stenosis patients on antiplatelet therapy.

METHODS

This prospective, multi-centre study assessed antiplatelet-HTPR status and its relationship with micro-emboli signals (MES) in asymptomatic vs. symptomatic ≥ 50-99% carotid stenosis. Platelet function/reactivity was assessed under 'moderately high shear stress' with the PFA-100^® and 'low shear stress' with VerifyNow^® and Multiplate^® analysers. Bilateral 1-h transcranial Doppler ultrasound of the middle cerebral arteries classified patients as MES + ve or MES - ve.

RESULTS

Data from 34 asymptomatic patients were compared with 43 symptomatic patients in the 'early phase' (≤ 4 weeks) and 37 patients in the 'late phase' (≥ 3 months) after TIA/ischaemic stroke. Median daily aspirin doses were higher in early symptomatic (225 mg; P < 0.001), but not late symptomatic (75 mg; P = 0.62) vs. asymptomatic patients (75 mg). There was a lower prevalence of aspirin-HTPR in early (28.6%; P = 0.028), but not late symptomatic (38.9%; P = 0.22) compared with asymptomatic patients (56.7%) on the PFA-100^®, but not on the VerifyNow^® or Multiplate^® (P ≤ 0.53). Early symptomatic patients had a higher prevalence of aspirin-HTPR on the PFA-100^® (28.6%) vs. VerifyNow^® (9.5%; P = 0.049), but not Multiplate^® assays (11.9%, P = 0.10). There was no difference in aspirin-HTPR prevalence between any symptomatic vs. asymptomatic MES + ve or MES - ve subgroup.

DISCUSSION

Recently symptomatic moderate-severe carotid stenosis patients had a lower prevalence of aspirin-HTPR than their asymptomatic counterparts on the PFA-100^®, likely related to higher aspirin doses. The prevalence of antiplatelet-HTPR was positively influenced by higher shear stress levels, but not MES status.

The Psychiatric Phenotype of Anti-NMDA Receptor Encephalitis

In its early stages, anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis is often characterized by prominent psychiatric manifestations that can lead to delays in diagnosis and treatment. The authors aimed to address this problem by providing a detailed description of the psychiatric phenotype and demographic features that may influence presentation. Eighty-six patients with positive serum NMDAR antibodies were identified, 22 of whom met diagnostic criteria for anti-NMDAR encephalitis. Medical notes were reviewed retrospectively to rate psychiatric symptoms using standardized scales. Clinical and demographic characteristics were compared for patients with and without psychosis. Patients with psychosis exhibited severe psychopathology with a characteristic phenotype: severe and disproportionate cognitive disturbance (p<0.005) with high negative symptom scores and excitability. Those presenting with psychotic symptoms were significantly younger than those without (p<0.005). Patients with anti-NMDAR encephalitis present with a somewhat distinct cluster of psychiatric symptoms not commonly seen in functional psychoses. When encountered, this atypical pattern should warrant further investigation and a high index of suspicion for anti-NMDAR encephalitis. The more prominent psychotic features in younger adults may reflect greater susceptibility of the young brain to exogenous psychosis.

Investigating adults with early-onset epilepsy and intellectual or physical disability

This article focuses on investigating adults with early-onset epilepsy and intellectual or physical disability within adult neurology services. We aim to guide general neurologists in the diagnostic reassessment of people with epilepsy and complex neurological problems of unknown cause. Following an overview, we address imaging, electroencephalography, genetic studies and metabolic testing, and give examples where diagnosis directly influences treatment. Aetiological diagnosis serves to inform prognosis, guide treatment and provide a framework for genetic counselling.

Glial fibrillary acidic protein antibody-positive meningoencephalomyelitis

Glial fibrillary acidic protein antibody-positive meningoencephalomyelitis is a newly described, possibly under-recognised, severe inflammatory condition of the nervous system. The clinical presentation is variable but most commonly is a combination of meningitis, encephalitis and myelitis; other manifestations may include seizures, psychiatric symptoms and tremor. There is a significant association with malignancies, often occult, and with other autoimmune conditions. Although the disease responds well to corticosteroids acutely, it typically relapses when these are tapered, and so patients need long-term immunosuppression. We report a young man presenting with subacute meningoencephalitis and subsequent myelitis, and discuss the typical presentation and management of this severe but treatable condition.

Review article: acute severe ulcerative colitis - evidence-based consensus statements

BACKGROUND

Acute severe ulcerative colitis (ASUC) is a potentially life-threatening complication of ulcerative colitis.

AIM

To develop consensus statements based on a systematic review of the literature of the management of ASUC to improve patient outcome.

METHODS

Following a literature review, the Delphi method was used to develop the consensus statements. A steering committee, based in Australia, generated the statements of interest. Three rounds of anonymous voting were carried out to achieve the final results. Acceptance of statements was pre-determined by ≥80% votes in 'complete agreement' or 'agreement with minor reservation'.

RESULTS

Key recommendations include that patients with ASUC should be: hospitalised, undergo unprepared flexible sigmoidoscopy to assess severity and to exclude cytomegalovirus colitis, and be provided with venous thromboembolism prophylaxis and intravenous hydrocortisone 100 mg three or four times daily with close monitoring by a multidisciplinary team. Rescue therapy such as infliximab or ciclosporin should be started if insufficient response by day 3, and colectomy considered if no response to 7 days of rescue therapy or earlier if deterioration. With such an approach, it is expected that colectomy rate during admission will be below 30% and mortality less than 1% in specialist centres.

CONCLUSION

These evidenced-based consensus statements on acute severe ulcerative colitis, developed by a multidisciplinary group, provide up-to-date best practice recommendations that improve and harmonise management as well as provide auditable quality assessments.

A chondrocyte infiltrated collagen type I/III membrane (MACI® implant) improves cartilage healing in the equine patellofemoral joint model

Autologous chondrocyte implantation (ACI) has improved outcome in long-term studies of joint repair in man. However, ACI requires sutured periosteal flaps to secure the cells, which precludes minimally-invasive implantation, and introduces complications with arthrofibrosis and graft hypertrophy. This study evaluated ACI on a collagen type I/III scaffold (matrix-induced autologous chondrocyte implantation; MACI(®)) in critical sized defects in the equine model.

METHODS

Chondrocytes were isolated from horses, expanded and seeded onto a collagen I/III membrane (ACI-Maix™) and implanted into one of two 15-mm defects in the femoral trochlear ridge of six horses. Control defects remained empty as ungrafted debrided defects. The animals were examined daily, scored by second look arthroscopy at 12 weeks, and necropsy examination 6 months after implantation. Reaction to the implant was determined by lameness, and synovial fluid constituents and synovial membrane histology. Cartilage healing was assessed by arthroscopic scores, gross assessment, repair tissue histology and immunohistochemistry, cartilage glycosaminoglycan (GAG) and DNA assay, and mechanical testing.

RESULTS

MACI(®) implanted defects had improved arthroscopic second-look, gross healing, and composite histologic scores, compared to spontaneously healing empty defects. Cartilage GAG and DNA content in the defects repaired by MACI implant were significantly improved compared to controls. Mechanical properties were improved but remained inferior to normal cartilage. There was minimal evidence of reaction to the implant in the synovial fluid, synovial membrane, subchondral bone, or cartilage.

CONCLUSIONS

The MACI(®) implant appeared to improve cartilage healing in a critical sized defect in the equine model evaluated over 6 months.

Increased thrombin generation potential in symptomatic versus asymptomatic moderate or severe carotid stenosis and relationship with cerebral microemboli

INTRODUCTION

The importance of thrombin generation in the pathogenesis of TIA or stroke and its relationship with cerebral microembolic signals (MES) in asymptomatic and symptomatic carotid stenosis has not been comprehensively assessed.

METHODS

Plasma thrombin generation parameters from patients with moderate or severe (≥ 50%) asymptomatic carotid stenosis were compared with those from patients with symptomatic carotid stenosis in the early (≤ 4 weeks) and late phases (≥ 3 months) after TIA or stroke in this prospective, pilot observational study. Thrombin generation profile was longitudinally assessed in symptomatic patients with data at each time point. Bilateral transcranial Doppler ultrasound monitoring of the middle cerebral arteries was performed whenever possible to classify patients as MES-positive or MES-negative.

RESULTS

Data from 31 asymptomatic, 46 'early symptomatic' and 35 'late symptomatic' patients were analysed. Peak thrombin (344.2 nM vs 305.3 nM; p = 0.01) and endogenous thrombin potential (1772.4 vs 1589.7; p = 0.047) were higher in early symptomatic than asymptomatic patients. Peak thrombin production decreased in symptomatic patients followed up from the early to late phase after TIA or stroke (339.7 nM vs 308.6 nM; p = 0.02). Transcranial Doppler ultrasound data were available in 25 asymptomatic, 31 early symptomatic and 27 late symptomatic patients. Early symptomatic MES-positive patients had a shorter 'time-to-peak thrombin' than asymptomatic MES-positive patients (p=0.04), suggesting a more procoagulant state in this early symptomatic subgroup.

DISCUSSION

Thrombin generation potential is greater in patients with recently symptomatic than asymptomatic carotid stenosis, and decreases over time following TIA or stroke associated with carotid stenosis. These data improve our understanding of the haemostatic/thrombotic biomarker profile in moderate-severe carotid stenosis.

The Confidential Enquiry into Maternal Deaths in South Africa: a case study

The Confidential Enquiry into Maternal Deaths (CEMD) in South Africa has been operational for 15 years. This case study describes the process of notification and independent assessment of maternal deaths, predominantly in facilities. In the earlier years of the Enquiry, institutional maternal mortality ratio increased and was 176.2 per 100 000 live births in the 2008-10 triennium; thereafter it decreased to 146.7 in the 2011/12 period. The slow progress was due to the significant contribution of HIV/AIDs to maternal mortality and challenges in implementing the recommendations that were devised from the findings of the Enquiry. Nevertheless, the CEMD process has been maintained and strengthened so it is currently able to perform routine maternal death surveillance at both national and district levels, identify deficiencies within the health system, generate reports and also provide early warning about alarming trends such as the increasing numbers of deaths due to caesarean-section-associated haemorrhage.

The appropriateness of a proton pump inhibitor prescription

Proton pump inhibitors (PPIs) are one of the most commonly prescribed groups of drug in Ireland, at great expense to the Irish healthcare executive. This study aims to evaluate the appropriateness of PPI prescriptions on admission and discharge in a tertiary referral hospital. All non-elective admissions in the Emergency Department in one week were included in the study. 102 patients in total were included, with 36 (35.4%) treated with a PPI on admission. Of these, only 3 (8.3%) had a clear indication noted as per current NICE guidelines. 18 new in-hospital PPI prescriptions were documented. 11 (61%) of which were present on discharge prescriptions. Continuing PPI prescription on discharge into the community may be inappropriate, costly and potentially harmful. Brief interventions aimed at reducing inappropriate PPI prescriptions have been shown to be effective at reducing the cost and potential harm of unnecessary treatment.

SUDEP and epilepsy-related mortality in pregnancy

Although data are limited, research in 2004 estimated a 10-fold increase in mortality in pregnancy in the United Kingdom in women with epilepsy (WWE) compared to women without epilepsy. We highlight epilepsy mortality in pregnancy based on the 2011 report of the United Kingdom Confidential Enquiries into Maternal Deaths, relating its findings to previous reports and epilepsy-rates in pregnancy. Among 2,291,493 maternities (2006-2008), we estimated 0.6% or 13,978 were in WWE. Fourteen deaths were epilepsy-related, of which 11 (79%) were sudden and unexpected (SUDEP). Nine occurred during pregnancy and five were postpartum. Nine (64%) were in women taking lamotrigine, seven as monotherapy. We estimated that 1:1,000 women died from epilepsy (mostly SUDEP) during or shortly after pregnancy. Epilepsy-related mortality is a significant risk in pregnancy. Antiepileptic drug-related factors may be relevant. The high proportion of women taking lamotrigine may reflect United Kingdom prescribing practice. Recent observations from the European and International Registry of Antiepileptic Drugs and Pregnancy (EURAP), whereby women on lamotrigine, the levels of which significantly decrease in pregnancy, had more difficulties with epilepsy control, argue against this being the sole explanation. Given the potential risks, every attempt should be made to prevent seizures, particularly convulsive, during pregnancy and postpartum. This, we believe, includes being proactive in maintaining lamotrigine levels during pregnancy.

Increased endothelial activation in recently symptomatic versus asymptomatic carotid artery stenosis and in cerebral microembolic-signal-negative patient subgroups

BACKGROUND AND PURPOSE

von Willebrand factor propeptide (VWF:Ag II) is potentially a more sensitive marker of acute endothelial activation than von Willebrand factor antigen (VWF:Ag). These biomarkers have not been simultaneously assessed in asymptomatic versus symptomatic carotid stenosis patients. The relationship between endothelial activation and cerebral microembolic signals (MESs) detected on transcranial Doppler ultrasound is unknown.

METHODS

In this multicentre observational analytical study, plasma VWF:Ag and VWF:Ag II levels in patients with ≥50% asymptomatic carotid stenosis were compared with those from patients with ≥50% symptomatic carotid stenosis in the 'early' (≤4 weeks) and 'late' (≥3 months) phases after transient ischaemic attack or ischaemic stroke. Endothelial activation was also longitudinally assessed in symptomatic patients during follow-up. Transcranial Doppler ultrasound monitoring classified patients as MES-positive or MES-negative.

RESULTS

Data from 31 asymptomatic patients were compared with those from 46 early symptomatic and 35 late phase symptomatic carotid stenosis patients, 23 of whom had undergone carotid intervention. VWF:Ag II levels were higher in early (12.8 μg/ml; P < 0.001), late (10.6 μg/ml; P = 0.01) and late post-intervention (10.6 μg/ml; P = 0.038) symptomatic patients than asymptomatic patients (8.9 μg/ml). VWF:Ag levels decreased in symptomatic patients followed up from the early to late phase after symptom onset (P = 0.048). Early symptomatic MES-negative patients had higher VWF: Ag II levels (13.3 vs. 9.0 μg/ml; P < 0.001) than asymptomatic MES-negative patients.

CONCLUSIONS

Endothelial activation is enhanced in symptomatic versus asymptomatic carotid stenosis patients, in early symptomatic versus asymptomatic MES-negative patients, and decreases over time in symptomatic patients. VWF:Ag II levels are a more sensitive marker of endothelial activation than VWF:Ag levels in carotid stenosis. The potential value of endothelial biomarkers and concurrent cerebral MES detection at predicting stroke risk in carotid stenosis warrants further study.

Clinical and biochemical improvements in a patient with MNGIE following enzyme replacement

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare autosomal recessive metabolic disorder caused by a deficiency of thymidine phosphorylase (TP, EC2.4.2.4) due to mutations in the nuclear gene TYMP. TP deficiency leads to plasma and tissue accumulations of thymidine and deoxyuridine which generate imbalances within the mitochondrial nucleotide pools, ultimately leading to mitochondrial dysfunction.¹ MNGIE is characterized clinically by leukoencephalopathy, external ophthalmoplegia, peripheral polyneuropathy, cachexia, and enteric neuromyopathy manifesting as gastrointestinal dysmotility. The condition is relentlessly progressive, with patients usually dying from a combination of nutritional and neuromuscular failure at an average age of 37 years.² Allogeneic hematopoietic stem cell transplantation (AHSCT) offers a permanent cure. Clinical and biochemical improvements following AHSCT have been reported but it carries a high mortality risk and is limited by matched donor availability.³ A consensus proposal for standardizing AHSCT recommends treatment of patients without irreversible end-stage disease and with an optimally matched donor; a majority of patients are ineligible and thus there is a critical requirement for an alternative treatment.⁴

Increased platelet activation in early symptomatic vs. asymptomatic carotid stenosis and relationship with microembolic status: results from the Platelets and Carotid Stenosis Study

BACKGROUND

Cerebral microembolic signals (MES) may predict increased stroke risk in carotid stenosis. However, the relationship between platelet counts or platelet activation status and MES in symptomatic vs. asymptomatic carotid stenosis has not been comprehensively assessed.

SETTING

University teaching hospitals.

METHODS

This prospective, pilot observational study assessed platelet counts and platelet activation status, and the relationship between platelet activation and MES in asymptomatic vs. early (≤ 4 weeks after TIA/stroke) and late phase (≥ 3 months) symptomatic moderate or severe (≥ 50%) carotid stenosis patients. Full blood count measurements were performed, and whole blood flow cytometry was used to quantify platelet surface activation marker expression (CD62P and CD63) and circulating leucocyte-platelet complexes. Bilateral simultaneous transcranial Doppler ultrasound monitoring of the middle cerebral arteries was performed for 1 h to classify patients as MES positive or MES negative.

RESULTS

Data from 31 asymptomatic patients were compared with 46 symptomatic patients in the early phase, and 35 of these patients were followed up to the late phase after symptom onset. The median platelet count (211 vs. 200 × 10(9)  L(-1) ; P = 0.03) and the median percentage of lymphocyte-platelet complexes was higher in early symptomatic than asymptomatic patients (2.8 vs. 2.4%; P = 0.001). The percentage of lymphocyte-platelet complexes was higher in early symptomatic than in asymptomatic patients with ≥ 70% carotid stenosis (P = 0.0005) and symptomatic patients recruited within 7 days of symptom onset (P = 0.028). Complete TCD data were available in 25 asymptomatic, 31 early phase symptomatic and 27 late phase symptomatic patients. Twelve per cent of asymptomatic vs. 32% of early phase symptomatic (P = 0.02) and 19% of late phase symptomatic patients (P = 0.2) were MES positive. Early symptomatic MES-negative patients had a higher percentage of lymphocyte-platelet complexes than asymptomatic MES-negative patients (2.8 vs. 2.3%; P = 0.0085).

DISCUSSION

Recently, symptomatic carotid stenosis patients have had higher platelet counts (potentially reflecting increased platelet production, mobilization or reduced clearance) and platelet activation status than asymptomatic patients. MES were more frequently detected in early symptomatic than asymptomatic patients, but the differences between late symptomatic and asymptomatic groups were not significant. Increased lymphocyte-platelet complex formation in recently symptomatic vs. asymptomatic MES-negative patients indicates enhanced platelet activation in this early symptomatic subgroup. Platelet biomarkers, in combination with TCD, have the potential to aid risk-stratification in asymptomatic and symptomatic carotid stenosis patients.

Local gene delivery of heme oxygenase-1 by adeno-associated virus into osteoarthritic mouse joints exhibiting synovial oxidative stress

OBJECTIVE

To evaluate the role of synovial oxidative stress on joint pathology in a spontaneous mouse model of osteoarthritis (OA) by intra-articular (IA) delivery of recombinant adeno-associated virus (rAAV) expressing anti-oxidant protein heme oxygenase-1 (HO-1).

METHODS

Joint transduction by rAAV vectors was evaluated with serotype 1, 2, 5 and 8 capsids carrying LacZ gene administered by IA injections into STR/ort mice. Transduced cell types were identified by β-galactosidase staining in sectioned joints. Effect of oxidative stress on AAV transduction of primary synoviocytes in vitro was quantitated by fluorescence-activated cell sorting (FACS) analysis. In vivo, the efficacy of rAAV1/HO-1 was tested by IA administration into STR/ort mice followed by histopathological scoring of cartilage. Levels of 3-nitrotyrosine (3-NT) and HO-1 were assessed by immunohistochemistry (IHC) of joint sections.

RESULTS

Administration of a rAAV1 based vector into OA mouse joints resulted in transduction of the synovium, joint capsule, adipocytes and skeletal muscle while none of the serotypes showed significant cartilage transduction. All OA joints exhibited significantly elevated levels of oxidative stress marker, 3-NT, in the synovium compared to OA-resistant CBA-strain of mice. In vitro studies demonstrated that AAV transgene expression in primary synoviocytes was augmented by oxidative stress induced by H(2)O(2) and that a rAAV expressing HO-1 reduced the levels of oxidative stress. In vivo, HO-1 was increased in the synovium of STR/ort mice. However, delivery of rAAV1/HO-1 into OA joints did not reduce cartilage degradation.

CONCLUSIONS

AAV-mediated HO-1 delivery into OA joints during active disease was not sufficient to improve cartilage pathology in this model.

Hylan G-F 20 maintains cartilage integrity and decreases osteophyte formation in osteoarthritis through both anabolic and anti-catabolic mechanisms

OBJECTIVE

To perform a molecular mechanism-based investigation of the chondroprotective potential of hylan G-F 20.

METHOD

The effects of hylan G-F 20 on IL-1β-induced glycosaminoglycan (GAG) depletion and matrix metalloproteinase (MMP) expression in bovine and human cartilage explants were evaluated. Three weekly intra-articular hylan G-F 20 or control injections were administered 4 weeks post-operatively to rabbits with surgically induced osteoarthritis (OA). Cartilage histopathologic scores and osteophyte size were evaluated at 1, 4, and 8 weeks post-injections. Histomorphometry and immunostaining were used to quantify cartilage area and type II collagen (Col II) intensity, and real-time polymerase chain reaction (PCR) was used to examine the mRNA levels of Col2A1, MMP-13, -16 and IL-1β at 1 week.

RESULTS

Hylan G-F 20 retained GAG in IL-1β-exposed bovine and human cartilage explants and abrogated IL-1β-mediated increases in MMP-1, -3, and -13 in human explant culture. Hylan G-F 20‒treated OA joints had significantly better cartilage integrity at 1 and 4 weeks post-treatment and significantly smaller osteophytes at 4 weeks compared with control. Col2A1 mRNA increased with hylan G-F 20 treatment, which correlated with a trend toward increased Col II immunostaining. MMP-13 and -16 mRNAs increased in OA cartilage, but were not significantly altered by hylan G-F 20. IL-1β mRNA was undetectable in cartilage and unaltered in the synovium.

CONCLUSIONS

Hylan G-F 20 improved cartilage integrity and decreased osteophyte formation in the rabbit model of OA. Our results suggest that hylan G-F 20 may stimulate cartilage repair by increasing Col II, and inhibit IL-1β-mediated matrix degradation by decreasing MMPs.

Clinical experience with oral lacosamide as adjunctive therapy in adult patients with uncontrolled epilepsy: a multicentre study in epilepsy clinics in the United Kingdom (UK)

INTRODUCTION

Lacosamide (LCS) is a new antiepileptic drug (AED) licensed in the European Union (EU) and United States (US) in 2008.

AIMS

To evaluate the efficacy and tolerability of add-on LCS in an out-patient epilepsy clinic setting to obtain useful information for everyday practice.

METHODS

We pooled data retrospectively from the case note of patients with refractory epilepsy in whom LCS had been prescribed in 19 hospitals across the United Kingdom.

RESULTS

Four hundred and three patients were included (mean age 41.9 years, 50.6% women, 18.1% with learning disabilities (LD)). Mean follow-up (FU) was 11.6 months (range one day to 42 months). Most patients (86.9%) presented with symptomatic partial epilepsy (SPE) and 80% were taking two or more antiepileptic drugs (AEDs) when LCS was added (mean 2, range 0-4). Retention rates were 80% at six months, 68% at one year and 45% at two years. The efficacy of LCS was evaluated at three months and at the final FU. At three months one hundred and eight patients (31.1%) reported ≥ 50% seizure reduction and 32 (9.2%) were seizure free. At the final FU 102 (37.5%) reported ≥ 50% seizures reduction and 28 (9.8%) were seizure free. One hundred and ninety three patients (48.7%) reported adverse effects (AEs). The most frequent were sedation and dizziness, followed by nausea. Lacosamide was discontinued in 150 patients (38%), 60 due to AEs alone.

CONCLUSION

LCS appears to be an effective and safe AED when used as adjunctive therapy in patients with refractory partial epilepsy.

Pregabalin as adjunctive therapy for partial epilepsy: an audit study in 96 patients from the South East of England

INTRODUCTION

Pregabalin (PGB) was licensed in the EU in 2004 as an adjunctive therapy in partial epilepsy. It is also licensed for neuropathic pain and generalised anxiety.

AIMS

To identify the clinical usefulness and side effects of add-on PGB in out-patient epilepsy clinics.

METHODS

We performed an audit on 96 consecutive patients (44 male) prescribed PGB for refractory epilepsy. Mean follow-up, for those who remained on PGB, was 23 months (range 12-39 months).

RESULTS

Fifty patients remained on PGB, 37 of whom reported clear improvement in seizure frequency. Among these 37 patients, 1 was seizure free for 15 months; 29 had a seizure reduction of >50%; and 7 improved by <50%. Eight patients reported a decrease in seizure severity without change in seizure frequency. Nine patients reported an incidental improvement in anxiety. Side effects were reported by 25 patients out of the 50 patients still on treatment: 12 reported drowsiness or tiredness, 8 weight gain, 7 dizziness, 2 headache, 2 cognitive side effects, 1 irritability, 1 itchiness, 1 anxiety, and 1 transient rash. Among the 46 patients who discontinued treatment, 9 had worsening of seizure frequency, 27 lack of efficacy and 9 intolerable side effects necessitating withdrawal (4 dizziness or drowsiness, 2 weight gain, 1 peripheral oedema, 1 pain in arms and legs, 1 irritability and cognitive side effects). One patient had a seizure related death (probably drowning) within 1 month of starting PGB.

CONCLUSION

Pregabalin seems to be an effective and well-tolerated anti-epileptic drug when used as add-on treatment in patients with refractory partial epilepsy.

Idiopathic Generalized Epilepsy with Absences: Syndrome Classification

In a cohort of 275 Caucasians with a broad IGE phenotype, patients with absences were classified. Criteria of the 1989 Commission on Classification of the International League Against Epilepsy for Childhood Absence Epilepsy (CAE 1989 criteria) were compared with the stricter criteria of the ILAE Task Force for Classification and Terminology (CAE 2005 criteria). Among the 129 patients with absences without significant myoclonus, 50 had juvenile absence epilepsy 44 had CAE according to the CAE 1989 criteria and only 30 had CAE according to the CAE 2005 criteria. We found a significantly better outcome in patients considered as CAE by the CAE 2005 criteria, compared with those excluded. Strict criteria for classification of absence syndromes leave many patients unclassified. However, diagnostic criteria used to classify CAE patients have prognostic significance. We propose that patients are classified as having benign CAE or as having CAE with the adverse prognostic factors indicated.

Erythropoietin Safety and Efficacy in Chronic Allograft Nephropathy

BACKGROUND

Patients with chronic allograft nephropathy (CAN) very frequently suffer anemia. Correction of anemia by means of recombinant erythropoietin (rEpo) is possible and useful, but safety and efficacy must be assessed.

METHODS

This multicenter, prospective, open study included patients with a cadaver renal transplant, CAN, and non-ferropenic anemia. The aim of the study was to determine the safety and efficacy of treatment with rEpo to target hematocrit (HCT) values around 35% and/or hemoglobin (Hb) levels of 11 g/dL.

RESULTS

Twenty-four patients were included: 71% males and 29% females aged 49.5 +/- 14 years. At last follow-up, 48% did not show anemia-related symptoms, and 19% experienced adverse events possibly or probably related to rEpo. In 86% of cases, anemia was corrected and in 71%, graft survival was conserved. Patients whose anemia was not corrected had poor initial renal function (sCr 5 +/- 1 mg/dL vs sCr 3.2 +/- 1 mg/dL, P = .028). Patients with graft survival showed correction of anemia (P = .001) on a relatively low dose of rEpo and without a significant increase in blood pressure.

CONCLUSIONS

All patients who had graft survival and only half of those who lost their graft showed a correction of anemia. The rEpo treatment neither accelerated nor decelerated renal failure. The difference between patients in whom anemia was corrected, or not, did not depend upon the previous level of HCT/Hb, but upon worse renal function. Thus, rEpo in patients with CAN is safe and effective, so administration should be initiated early to avoid adverse events deriving from anemia.

Paracetamol overdose as a result of dental pain requiring medical treatment – two case reports

Two cases of unintentional paracetamol overdose are presented. Over a one month period these patients presented to an Accident and Emergency (A&E) department with symptoms of paracetamol toxicity, following the ingestion of large quantities of analgesia for the self treatment of dental pain. In one case the patient had no access to a dentist. Both patients required admission under the care of the medical on-call team and required anti-toxicity treatment to prevent permanent liver injury. Subsequent referrals were made to the oral and maxillofacial surgery team who provided emergency dental treatment and advice on further dental care. This paper highlights the significant signs and symptoms of paracetamol overdose about which dental practitioners should be aware. It also describes the management principles required to prevent potentially life threatening liver damage. Discussion is also made of the potential impact on patients struggling to cope with pulpal pain without access to a general dental practitioner.

No Association of Single Nucleotide Polymorphisms in the ?-Opioid Receptor Subunit Gene with Idiopathic Generalized Epilepsy

We have investigated the reported association (p = 0.019) between the A118G single nucleotide polymorphism (SNP) of the opioid receptor micro subunit gene (OPRM1) and idiopathic absence epilepsy (IAE). Five SNPs, including A118G, were investigated by association studies in a sample of 240 probands with idiopathic generalized epilepsy (IGE), including 110 with IAE, and 257 controls. No significant association was found for A118G with IGE or IAE. The difference between the two studies was in the control samples that had significantly different allele frequencies (p = 0.00005), suggesting that population stratification may explain the earlier significant association with IAE. In the current study, none of the other four SNPs was significantly associated with IGE or IAE. Our results provide no support for association of A118G with either IAE or IGE and also exclude association in our sample of a small-to-moderate gene effect with IGE from a large part of OPRM1.

A novel functional role for the highly conserved alpha-subunit KVGFFKR motif distinct from integrin alphaIIbbeta3 activation processes

BACKGROUND

The highly conserved integrin alpha-subunit membrane-proximal motif KVGFFKR plays a decisive role in modulating the activation of integrin alphaIIbbeta3. Previously, we have shown that a platelet permeable palmityl (pal)-peptide with this seven amino acid sequence can directly activate alphaIIbbeta3 leading to platelet aggregation.

OBJECTIVES

To investigate further the role of the KVGFFKR motif in integrin alphaIIbbeta3 function.

METHODS

We used two sequence-specific complementary model systems, palmityl pal-peptides in platelets, and mutant alphaIIbbeta3-expressing Chinese Hamster Ovary (CHO) cell lines.

RESULTS

In platelets we show that the two phenylalanine amino acids in pal-KVGFFKR (pal-FF) peptide are critical for stimulating platelet aggregation. Pal-FF peptide treatment of platelets also gives rise to a tyrosine phosphorylation signal despite the presence of inhibitors of fibrinogen binding. In CHO cells, a double alanine substitution, alphaIIb(F992A, F993A)beta3, induces constitutive integrin activation but prevents actin stress fiber formation upon adhesion to fibrinogen, suggesting that alphaIIbbeta3-mediated cytoskeletal reorganization is also dependent on F992 and F993. This further highlights a critical role for the two phenylalanine residues in both of these alphaIIbbeta3-mediated processes.

CONCLUSION

In addition to regulating integrin alphaIIbbeta3 activation state, the KVGFFKR motif also influences cytoskeletal reorganization. This activity is critically determined by F992 and F993 within the seven amino acid sequence.

Monitoring modulators of platelet aggregation in a microtiter plate assay

Platelets play a central role in maintaining biological hemostasis. Inappropriate platelet activation is responsible for thrombotic diseases such as myocardial infarction and stroke. Therefore, novel agents that can inhibit platelet activation are necessary. However, assays that monitor platelet aggregation are generally time-consuming and require high volumes of blood and specialized equipment. Therefore, a medium- to high-throughput assay that can monitor platelet aggregation would be considered useful. Such an assay should be sensitive, comparable to the "gold standard" assay of platelet aggregometry, and able to monitor multiple samples simultaneously but with low assay volumes. We have developed such a microtiter assay. It can assay an average of 60 independent treatments per 60 ml blood donation and demonstrates greater sensitivity than the current gold standard assay, namely platelet aggregation in stirring conditions in a platelet aggregometer. The microtiter plate (MTP) assay can detect known inhibitors of platelet function such as indomethacin, aspirin, and ReoPro. It is highly reproducible when using standard doses of agonists such as thrombin receptor-activating peptide (20 microM) and collagen (0.19 mg/ml). Finally, the MTP assay is rapid and sensitive and can detect unknown platelet-modulating agents from a library of compounds.

Evidence for a differential functional regulation of the two beta(3)-integrins alpha(V)beta(3) and alpha(IIb)beta(3)

The functional regulation of integrins is a major determinant of cell adhesion, migration and tissue maintenance. The binding of cytoskeletal proteins to various sites of integrin cytoplasmic domains is a key mechanism of this functional regulation. Expression of recombinant integrin alpha(IIb)beta(3) and alpha(M)beta(2) lacking the GFFKR-region in CHO cells results in constitutively activated integrins. In contrast, CHO cells stably expressing either a GFFKR-deleted alpha(V(del))beta(3) or a FF to AA-substituted alpha(V(AA))beta(3) do not reveal a constitutively activated integrin. Adhesion to immobilized fibrinogen is strongly impaired in alpha(V(del))beta(3) or alpha(V(AA))beta(3)-expressing cells, whereas it is not impaired in alpha(IIb)beta(3) and alpha(M)beta(2), both lacking the GFFKR-region. In a parallel plate flow chamber assay, alpha(V)beta(3)-expressing cells adhere firmly to fibrinogen and spread even at shear rates of 15 to 20 dyn/cm(2), whereas alpha(V(del))beta(3) or alpha(V(AA))beta(3) cells are detached at 15 dyn/cm(2). Actin stress fiber formation and focal adhesion plaques containing alpha(V)beta(3) are observed in alpha(V)beta(3) cells but not in alpha(V(del))beta(3) or alpha(V(AA))beta(3)-expressing cells. As an additional manifestation of impaired outside-in signaling, phosphorylation of pp125(FAK) was reduced in these cells. In summary, we report that the GFFKR-region of the alpha(V)-cytoplasmic domain and in particular two phenylalanines are essential for integrin alpha(V)beta(3) function, especially for outside-in signaling. Our results suggest that the two beta(3)-integrins alpha(IIb)beta(3) and alpha(V)beta(3) are differentially regulated via their GFFKR-region.

A palmitylated peptide derived from the glycoprotein Ib beta cytoplasmic tail inhibits platelet activation

The platelet receptor GPIb/IX/V mediates a crucial role in hemostasis, yet the signaling mechanisms involved are incompletely understood. The complex consists of four polypeptides GPIb alpha, GPIb beta, GPIX and GPV. We identified an amino acid sequence in the cytoplasmic tail of the GPIb beta subunit between residues R151 and A161 that is highly conserved across species and hypothesized that it has functional importance. To target this motif, we synthesized a corresponding cell-permeable palmitylated peptide (Pal-RRLRARARARA) and investigated its effect on platelet function. Pal-RRLRARARARA completely inhibited low dose thrombin- and ristocetin-induced aggregation in washed platelets but only partially inhibited collagen- and U46619-induced aggregation. Thromboxane production in platelets stimulated with thrombin was significantly reduced by Pal-RRLRARARARA compared with collagen. Activation of the integrin alpha IIb beta 3 in response to thrombin was significantly reduced when platelets were preincubated with Pal-RRLRARARARA. The adhesion of washed platelets to von Willebrand factor (VWF) under static conditions was significantly reduced by Pal-RRLRARARARA. Under conditions of high shear, the velocity of platelets rolling on VWF was significantly increased when platelets are preincubated with Pal-RRLRARARARA. This study defines a novel function for the RRLRARARARA motif of GPIb beta in platelet activation.

Extracellular protons inhibit the activity of inward-rectifying potassium channels in the motor cells of Samanea saman pulvini

The intermittent influx of K+ into motor cells in motor organs (pulvini) is essential to the rhythmic movement of leaves and leaflets in various plants, but in contrast to the K+ influx channels in guard cells, those in pulvinar motor cells have not yet been characterized. We analyzed these channels in the plasma membrane of pulvinar cell protoplasts of the nyctinastic legume Samanea saman using the patch-clamp technique. Inward, hyperpolarization-activated currents were separated into two types: time dependent and instantaneous. These were attributed, respectively, to K+ -selective and distinctly voltage-dependent K(H) channels and to cation-selective voltage-independent leak channels. The pulvinar K(H) channels were inhibited by external acidification (pH 7.8-5), in contrast to their acidification-promoted counterparts in guard cells. The inhibitory pH effect was resolved into a reversible decline of the maximum conductance and an irreversible shift of the voltage dependence of K(H) channel gating. The leak appeared acidification insensitive. External Cs (10 mM in 200 mM external K+) blocked both current types almost completely, but external tetraethylammonium (10 mM in 200 mM external K+) did not. Although these results do not link these two channel types unequivocally, both likely serve as K+ influx pathways into swelling pulvinar motor cells. Our results emphasize the importance of studying multiple model systems.

A Val193Met mutation in GPIIIa results in a GPIIb/IIIa receptor with a constitutively high affinity for a small ligand

We have identified a patient designated as (GTa) with Glanzmann's Thrombasthenia (GT) diagnosed on the basis of a prolonged bleeding time and failure of the patient's platelets to aggregate. The number of glycoprotein (GP)IIb/IIIa receptors on the platelet surface was 37% of normal and those receptors displayed a defect in soluble fibrinogen binding. Nevertheless, GTa platelets showed increased adhesion to solid-phase fibrinogen and binding affinity for the RGD-mimetic (3)H-SC52012, a non-peptide GPIIb/IIIa antagonist. Dithiothreitol (DTT) and ADP enhanced the affinity for [(3)H]-SC52012 in normal platelets, but had little effect in GTa platelets. These findings suggested that GTa platelets were locked in an altered affinity state. Genetic analysis showed that GTa was a compound heterozygote for the GPIIIa gene. One allele showed a deletion at the 3' end of exon 3 resulting in a premature stop codon. The second GPIIIa allele had a G to A transition at nucleotide 577, resulting in a Val193Met substitution. HEK 293T cells transfected with mutant GPIIb/IIIaV193M bound [(3)H]-SC52012 with a higher affinity than wild-type GPIIb/IIIa, and this was not increased by DTT. The mutant receptor distinguishes between platelet adhesion and aggregation, and demonstrates the phenotype that may be expected when platelet aggregation alone is inhibited.

Potassium-efflux channels in extensor and flexor cells of the motor organ of Samanea saman are not identical. Effects of cytosolic calcium

Leaflet movements in the mimosa-family tree Samanea saman stem from coordinated volume changes of cells in the leaf motor organs in the adaxial and abaxial motor cells ("flexors" and "extensors"). Shrinking, initiated by dissimilar light signals in extensors and in flexors, depends in both cell types on K(+) efflux via depolarization-dependent potassium (K(D)) channels. To compare between flexor and extensor K(D) channels and to test for a possible interaction of these channels with the Ca(2+)-mobilizing phosphoinositide cascade evoked in these motor cells by the "shrinking signals," we probed the channels with varying (5 nM-3 mM) cytosolic free-Ca(2+) concentration ([Ca(2+)](cyt)) in patch-clamped inside-out excised membrane patches. Ca(2+) was not required for K(D) channel activation. [Ca(2+)](cyt) of 600 nM decreased the mean number of open K(D) channels in flexors, as monitored at -30 mV. Detailed analysis revealed that in flexors millimolar [Ca(2+)](cyt) decreased the maximum number of open channels, but simultaneously increased K(D) channel opening probability by negatively shifting the half-maximum-activation voltage by 40 to 50 mV. Thus, the promoting and the inhibitory effects at millimolar [Ca(2+)](cyt) practically cancelled-out. In contrast to flexors, none of the gating parameters of the extensor K(D) channels were affected by [Ca(2+)](cyt). Irrespective of [Ca(2+)](cyt), the steady-state gating of extensor K(D) channels was slightly but significantly more voltage sensitive than that of flexors. The unitary conductances of flexor and extensor K(D) channels were similar and decreased by approximately 20% at millimolar [Ca(2+)](cyt). It is intriguing that the extensor K(D) channels were significantly less K(+) selective than those in flexors.

Patients' perspectives on services for epilepsy: a survey of patient satisfaction, preferences and information provision in 2394 people with epilepsy

The objectives of this study were to provide a comprehensive survey of satisfaction with care, care preferences and information provision for patients with epilepsy, and to formulate recommendations for the development of epilepsy services based on the findings. A questionnaire was distributed to 4620 patients who were currently receiving antiepileptic drugs for epilepsy, regardless of aetiology, duration or severity. Two different samples of patients with epilepsy were questioned: the first an unselected sample drawn from primary care, and the second consisting of consecutive patients drawn from hospital clinics. There were 2394 responses to the questionnaire. Satisfaction with primary and hospital care was high, both overall and for specific aspects. However, two major shortcomings were identified. First, few respondents felt that their care was shared between hospital and GP. Secondly, provision of information about epilepsy was perceived to be poor, particularly by the elderly. Younger patients and patients with severe epilepsy had a higher satisfaction with and preference for hospital care, whereas older age groups were more satisfied with and preferred primary care. Patients' main reasons for preferring primary care were that it was more personal and the GP was more familiar with them, and secondary care was preferred because the hospital doctor knew more about epilepsy. In conclusion, we have conducted the largest representative UK survey of patients' perceptions and views of the care available for epilepsy. Although patient satisfaction was high, information provision is poor and the shared care model is not operating effectively. We recommend that an emphasis be placed on methods for improving the interface between primary and secondary care. The setting up of hospital epilepsy centres, as recommended by the recently published Clinical Standards Advisory Group report on epilepsy, would provide a focus for these efforts and for information provision.

NHS services for epilepsy from the patient's perspective: a survey of primary, secondary and tertiary care access throughout the UK

The aims of this study were to estimate the proportion of patients with epilepsy who made primary care and/or hospital outpatient medical consultations within 1 year; to formulate a model of the explanatory variables that influence whether patients consult or not; and to estimate the frequency of referral to, and waiting time for, hospital outpatient clinics in patients with new-onset seizures. Suggestions are offered for improvement of epilepsy services based on the findings. A questionnaire was distributed to 3455 unselected patients identified at population level from primary care practices in all NHS regions of the UK. There were 1652 respondents with epilepsy of all types, irrespective of aetiology, duration or severity. Fifty-two per cent of the whole sample made at least one medical consultation of any type specifically for epilepsy (42.0% primary care, 30.5% hospital, 20.4% both). Most patients with controlled epilepsy (74.5%) had no consultations. Of patients with severe epilepsy, 27.5% made no primary care consultations, 43.4% no hospital consultations and 14.1% no consultations of either type. Gender did not influence the likelihood of either GP or hospital consultations in patients with either controlled or active epilepsy. Increasing seizure frequency was associated with a greater likelihood of one or more hospital consultations for epilepsy, whereas increasing duration of epilepsy was associated with a decreased likelihood of either type of consultation. Age affected consultation rates: of those patients over the age of 65 years, only 29.9% made a medical consultation for epilepsy, compared to 53.8% of young adults. Patients under the age of 17 years were less likely to have consulted a GP and more likely to have consulted a hospital doctor. Ninety percent of new-onset patients had been referred to a hospital doctor, and the mean wait was 6.5 weeks. In conclusion, many patients with epilepsy, including severe epilepsy, are not receiving specialist input, and a significant proportion are receiving no medical supervision. The elderly are over-represented in this group. Care tends to be polarized between hospital or primary care, falling short of the ideal of shared care. It will be important to address the influences on consultation seeking in epilepsy, particularly for those patients currently under no medical supervision.

The platelet integrin alpha IIbbeta 3 has an endogenous thiol isomerase activity

Integrins are cysteine-rich heterodimeric cell-surface adhesion molecules that alter their affinity for ligands in response to cellular activation. The molecular mechanisms involved in this activation of integrins are not understood. Treatment with the thiol-reducing agent, dithiothreitol, can induce an activation-like state in many integrins suggesting that cysteine-cysteine dithiol bonds are important for the receptor's tertiary structure and may be involved in activation-induced conformational changes. Here we demonstrate that the platelet-specific integrin, alpha(IIb)beta(3), contains an endogenous thiol isomerase activity, predicted from the presence of the tetrapeptide motif, CXXC, in each of the cysteine-rich repeats of the beta(3) polypeptide. This motif comprises the active site in enzymes involved in disulfide exchange reactions, including protein-disulfide isomerase (EC ) and thioredoxin. Intrinsic thiol isomerase activity is also observed in the related integrin, alpha(v)beta(3), which shares a common beta-subunit. Thiol isomerase activity within alpha(IIb)beta(3) is time-dependent and saturable, and is inhibited by the protein-disulfide isomerase inhibitor, bacitracin. Furthermore, this activity is calcium-sensitive and is regulated in the EDTA-stabilized conformation of the integrin. This novel demonstration of an enzymatic activity associated with an integrin subunit suggests that altered thiol bonding within the integrin or its substrates may be locally modified during alpha(IIb)beta(3) activation.

Potassium-efflux channels in extensor and flexor cells of the motor organ of Samanea saman are not identical. Effects of cytosolic calcium

Leaflet movements in the mimosa-family tree Samanea saman stem from coordinated volume changes of cells in the leaf motor organs in the adaxial and abaxial motor cells ("flexors" and "extensors"). Shrinking, initiated by dissimilar light signals in extensors and in flexors, depends in both cell types on K(+) efflux via depolarization-dependent potassium (K(D)) channels. To compare between flexor and extensor K(D) channels and to test for a possible interaction of these channels with the Ca(2+)-mobilizing phosphoinositide cascade evoked in these motor cells by the "shrinking signals," we probed the channels with varying (5 nM-3 mM) cytosolic free-Ca(2+) concentration ([Ca(2+)](cyt)) in patch-clamped inside-out excised membrane patches. Ca(2+) was not required for K(D) channel activation. [Ca(2+)](cyt) of 600 nM decreased the mean number of open K(D) channels in flexors, as monitored at -30 mV. Detailed analysis revealed that in flexors millimolar [Ca(2+)](cyt) decreased the maximum number of open channels, but simultaneously increased K(D) channel opening probability by negatively shifting the half-maximum-activation voltage by 40 to 50 mV. Thus, the promoting and the inhibitory effects at millimolar [Ca(2+)](cyt) practically cancelled-out. In contrast to flexors, none of the gating parameters of the extensor K(D) channels were affected by [Ca(2+)](cyt). Irrespective of [Ca(2+)](cyt), the steady-state gating of extensor K(D) channels was slightly but significantly more voltage sensitive than that of flexors. The unitary conductances of flexor and extensor K(D) channels were similar and decreased by approximately 20% at millimolar [Ca(2+)](cyt). It is intriguing that the extensor K(D) channels were significantly less K(+) selective than those in flexors.

A fast signal-induced activation of Poly(ADP-ribose) polymerase: a novel downstream target of phospholipase c

We present the first evidence for a fast activation of the nuclear protein poly(ADP-ribose) polymerase (PARP) by signals evoked in the cell membrane, constituting a novel mode of signaling to the cell nucleus. PARP, an abundant, highly conserved, chromatin-bound protein found only in eukaryotes, exclusively catalyzes polyADP-ribosylation of DNA-binding proteins, thereby modulating their activity. Activation of PARP, reportedly induced by formation of DNA breaks, is involved in DNA transcription, replication, and repair. Our findings demonstrate an alternative mechanism: a fast activation of PARP, evoked by inositol 1,4,5,-trisphosphate-Ca(2+) mobilization, that does not involve DNA breaks. These findings identify PARP as a novel downstream target of phospholipase C, and unveil a novel fast signal-induced modification of DNA-binding proteins by polyADP-ribosylation.

Surface expression of glycoprotein ib alpha is dependent on glycoprotein ib beta: evidence from a novel mutation causing Bernard-Soulier syndrome

Bernard-Soulier syndrome is a rare bleeding disorder caused by a quantitative or qualitative defect in the platelet glycoprotein (GP) Ib-IX-V complex. The complex, which serves as a platelet receptor for von Willebrand factor, is composed of 4 subunits: GPIb alpha, GPIb beta, GPIX, and GPV. We here describe the molecular basis of a novel form of Bernard-Soulier syndrome in a patient in whom the components of the GPIb-IX-V complex were undetectable on the platelet surface. Although confocal imaging confirmed that GPIb alpha was not present on the platelet surface, GPIb alpha was readily detectable in the patient's platelets. Moreover, immunoprecipitation of plasma with specific monoclonal antibodies identified circulating, soluble GPIb alpha. DNA-sequence analysis revealed normal sequences for GPIb alpha and GPIX. There was a G to A substitution at position 159 of the gene encoding GPIb beta, resulting in a premature termination of translation at amino acid 21. Studies of transient coexpression of this mutant, W21stop-GPIb beta, together with wild-type GPIbalpha and GPIX, demonstrated a failure of GPIX expression on the surface of HEK 293T cells. Similar results were obtained with Chinese hamster ovary alpha IX cells, a stable cell line expressing GPIbalpha that retains the capacity to re-express GPIX. Thus, we found that GPIbbeta affects the surface expression of the GPIb-IX complex by failing to support the insertion of GPIb alpha and GPIX into the platelet membrane. (Blood. 2000;96:532-539)