p62/SQSTM1 in liver diseases: the usual suspect with multifarious identities

p62/Sequestosome-1 (SQSTM1) is a selective autophagy receptor that recruits and delivers intracellular substrates for bulk clearance through the autophagy lysosomal pathway. Interestingly, p62 also serves as a signaling scaffold to participate in the regulation of multiple physiological processes, including oxidative stress response, metabolism, inflammation, and programmed cell death. Perturbation of p62 activity has been frequently found to be associated with the pathogenesis of many liver diseases. p62 has been identified as a critical component of protein aggregates in the forms of Mallory-Denk bodies (MDBs) or intracellular hyaline bodies (IHBs), which are known to be frequently detected in biopsy samples from alcoholic steatohepatitis (ASH), non-alcoholic steatohepatitis (NASH), and hepatocellular carcinoma (HCC) patients. Importantly, abundance of these p62 inclusion bodies is increasingly recognized as a biomarker for NASH and HCC. Although the level of p62 bodies seems to predict the progression and prognosis of these liver diseases, understanding of the underlying mechanisms by which p62 regulates and contributes to the development and progression of these diseases remains incomplete. In this review, we will focus on the function and regulation of p62, and its pathophysiological roles in the liver, by critically reviewing the findings from preclinical models that recapitulate the pathogenesis and manifestation of these liver diseases in humans. In addition, we will also explore the suitability of p62 as a predictive biomarker and a potential therapeutic target for the treatment of liver diseases, including NASH and HCC, as well as recent development of small-molecule compounds for targeting the p62 signaling axis.

Trajectory of immune evasion and cancer progression in hepatocellular carcinoma

Immune evasion is key to cancer initiation and later at metastasis, but its dynamics at intermediate stages, where potential therapeutic interventions could be applied, is undefined. Here we show, using multi-dimensional analyses of resected tumours, their adjacent non-tumour tissues and peripheral blood, that extensive immune remodelling takes place in patients with stage I to III hepatocellular carcinoma (HCC). We demonstrate the depletion of anti-tumoural immune subsets and accumulation of immunosuppressive or exhausted subsets along with reduced tumour infiltration of CD8 T cells peaking at stage II tumours. Corresponding transcriptomic modification occur in the genes related to antigen presentation, immune responses, and chemotaxis. The progressive immune evasion is validated in a murine model of HCC. Our results show evidence of ongoing tumour-immune co-evolution during HCC progression and offer insights into potential interventions to reverse, prevent or limit the progression of the disease.

Performance and 12 month outcomes of a wire free fractional flow reserve system for assessment of coronary artery disease, first experience in south east asia

Funding Acknowledgements

Type of funding sources: None.

Background

Fractional flow reserve (FFR) using an invasive pressure wire has a Class 1A recommendation for guiding coronary revascularization in stable coronary artery disease (CAD). Angiography based ‘wire free’ FFR is an emerging technique which determines the physiological significance of a coronary lesion without requirement of a pressure wire or induction of hyperemia. It also eliminates potential complications associated with introduction of wires into the coronary arteries.

Objective

To assess the 12-month clinical outcomes of PCI deferral, guided by an angiography based fractional flow reserve (CAFFR) system. The primary end point was a composite of death from any cause, myocardial infarction (MI) or target vessel revascularization (TVR)

Methods

This was a prospective, single center study involving 69 patients (93 vessels) with angiographic stenosis of 30%-90%. Patients with CAFFR of <0.80 or poor image quality were excluded leaving 29 patients (31 vessels) for analysis. All recruited patients had a CAFFR >0.80 and thus, PCI deferral.

Wired FFR was done for comparison on 14 patients (48%) at the operator’s discretion.

Results

The mean age was 59 ± 12.6 years old. Majority of patients (83%) were male. 12 (42%) patients were diabetic, 18 (62%) were hypertensive, 17 (59%) had dyslipidemia and 18 (62%) had a smoking history. The mean LVEF was 52+/-11.4%. 72% of the patients had a recent acute coronary syndrome. We assessed the LAD artery in 15 (52%) vessels. The mean CAFFR and FFR was 0.87 ± 0.04 and 0.89 ± 0.05 respectively. The values showed agreement with each other with no statistically significant proportional bias on the Bland Altman plot (linear regression t test: t=-1.19, p = 0.257). CAFFR values >0.80 showed 100% correspondence to negative FFR values (>0.80). There were zero procedural complications from CAFFR measurement.

At 12 months, all 29 patients were alive. Only 1 patient (3.4%) met the primary end point (TVR for angina). 89.6% (26) patients remained in CCS class 1 on follow up.

Conclusion

CAFFR shows good agreement with wired FFR. The 12-month outcome data shows that CAFFR guided PCI deferral is safe and comparable to the gold standard of wired FFR guided PCI deferral. Further analysis with a larger patient pool and longer follow-up is warranted. Abstract Figure. Bland-Altman plot of FFR and CAFFR

Three year clinical outcomes of fractional flow reserve guided coronary revascularization using a monorail pressure sensor microcatheter

Funding Acknowledgements

Type of funding sources: None.

Background

Fractional flow reserve (FFR) has a Class 1A recommendation for guiding coronary revascularization in stable coronary artery disease. Deferral of revascularization for coronary stenosis of FFR >0.80 has shown favorable long-term outcomes, yet the adoption in real-world practice is limited. To date, there is no study on FFR guided PCI in the Malaysian population.

Objective

(1) To explore the 3-year clinical outcome of FFR guided coronary revascularization.

(2) To compare the clinical outcome of FFR guided deferral of coronary revascularization versus FFR guided revascularization. The primary outcome was a composite of all cause mortality, non fatal myocardial infarction (MI) and ischemia driven target vessel revascularization (TVR)

Results

Thirty-five patients were lost to follow up leaving 78 patients (95 vessels) for final analysis. The mean age was 59.3 ± 9.4 years old. 69 (88.5%) patients were male, 24 (30.7%) had diabetes mellitus, 58 (74.3%) had dyslipidemia, 61 (78.2%) had hypertension and 45 (57.7%) were smokers. The mean LVEF was 56.7 ± 14.7%. FFR to the LAD artery was performed in 64 (82%) patients. Based on the FFR value of 0.80, 47 (60.2%) patients had FFR guided deferral of coronary revascularization and 31 (39.7%) patients had FFR guided revascularization.

At 3 years, 11 (14.1%) patients met the primary outcome, mainly driven by all-cause mortality (11.5%). The primary outcome was met in 14.9% of FFR guided deferral versus 12.9% of FFR guided revascularization (p = 0.828). All-cause mortality was 12.7% in patients with FFR guided deferral compared to 9.7% in patients with FFR guided revascularization at 3 years (p = 0.712). 

Cox proportional hazards model did not demonstrate any independent predictors associated with the primary outcome or all cause mortality. 

Conclusion

FFR guided deferral of revascularization was safe and had comparable long-term clinical outcomes to FFR guided PCI. To our knowledge, this is the first study on long-term clinical outcome on FFR guided revascularization in Malaysia. Abstract Figure. Kaplan-Meier curve primary end point  Abstract Figure. Kaplan-Meier curve all cause mortality

The BAX-binding protein MOAP1 associates with LC3 and promotes closure of the phagophore

MOAP1 (modulator of apoptosis 1) is a BAX-binding protein tightly regulated by the ubiquitin-proteasome system. Apoptotic stimuli stabilize MOAP1 protein and facilitate its interaction with BAX to promote apoptosis. Here we show that in contrast to being resistant to apoptotic stimuli, MOAP1-deficient cells are hypersensitive to cell death mediated by starvation rendered by EBSS treatment. MOAP1-deficient cells exhibited impairment in macroautophagy/autophagy signaling induced by EBSS. Mechanistic analysis revealed that MOAP1-deficient cells had no notable defect in the recruitment of the pre-autophagosomal phosphatidylinositol-3-phosphate (PtdIns3P)-binding proteins, ZFYVE1/DFCP1 and WIPI2, nor in the LC3 lipidation mechanism regulated by the ATG12-ATG5-ATG16L1 complex upon EBSS treatment. Interestingly, MOAP1 is required for facilitating efficient closure of phagophore in the EBSS-treated cells. Analysis of LC3-positive membrane structures using Halo-tagged LC3 autophagosome completion assay showed that predominantly unclosed phagophore rather than closed autophagosome was present in the EBSS-treated MOAP1-deficient cells. The autophagy substrate SQSTM1/p62, which is normally contained within the enclosed autophagosome under EBSS condition, was also highly sensitive to degradation by proteinase K in the absence of MOAP1. MOAP1 binds LC3 and the binding is critically dependent on a LC3-interacting region (LIR) motif detected at its N-terminal region. Re-expression of MOAP1, but not its LC3-binding defective mutant, MOAP1-LIR, in the MOAP1-deficient cells, restored EBSS-induced autophagy. Together, these observations suggest that MOAP1 serves a distinct role in facilitating autophagy through interacting with LC3 to promote efficient phagophore closure during starvation.Abbreviations CQ: Chloroquine; EBSS: Earle's Balanced Salt Solution; GABARAP: Gamma-Amino Butyric Acid Receptor Associated Protein; IF: Immunofluorescence; IP: Immunoprecipitation; LAMP1: Lysosomal-Associated Membrane Protein 1; LIR: LC3-Interacting Region; MAP1LC3/LC3: Microtubule Associated Protein 1 Light Chain 3; MEF: Mouse Embryonic Fibroblast; MOAP1: Modulator of Apoptosis 1; PE: Phosphatidylethanolamine; PtdIns3K: class III PtdIns3K complex I; PtdIns3P: Phosphatidylinositol-3-phosphate; STX17: Syntaxin 17; ULK1: unc-51 like autophagy activating kinase 1.

MOAP-1-mediated dissociation of p62/SQSTM1 bodies releases Keap1 and suppresses Nrf2 signaling

Nrf2 signaling is vital for protecting cells against oxidative stress. However, its hyperactivation is frequently found in liver cancer through excessive build‐up of p62/SQSTM1 bodies that sequester Keap1, an adaptor of the E3‐ubiquitin ligase complex for Nrf2. Here, we report that the Bax‐binding protein MOAP‐1 regulates p62‐Keap1‐Nrf2 signaling through disruption of p62 bodies. Upon induction of cellular stresses that stimulate formation of p62 bodies, MOAP‐1 is recruited to p62 bodies and reduces their levels independent of the autophagy pathway. MOAP‐1 interacts with the PB1‐ZZ domains of p62 and interferes with its self‐oligomerization and liquid–liquid phase separation, thereby disassembling the p62 bodies. Loss of MOAP‐1 can lead to marked upregulation of p62 bodies, enhanced sequestration of Keap1 by p62 and hyperactivation of Nrf2 antioxidant target genes. MOAP‐1‐deficient mice exhibit an elevated tumor burden with excessive levels of p62 bodies and Nrf2 signaling in a diethylnitrosamine (DEN)‐induced hepatocarcinogenesis model. Together, our data define MOAP‐1 as a negative regulator of Nrf2 signaling via dissociation of p62 bodies.

P13 Safety and efficacy of sacubitril-valsartan initiation during and after acute decompensated heart failure with reduced ejection fraction

Background

The PIONEER-HF trial has demonstrated the safety of Sacubitril-Valsartan initiation during acute decompensated heart failure (ADHF) compared to Enalapril. The efficacy outcome was also addressed by the surrogate end point of reduction in NT-proBNP. However, the safety and efficacy of Sacubitril-Valsartan initiation during ADHF compared to initiation after ADHF was unknown.

Objectives

(1) To compare the safety and efficacy of Sacubitril-Valsartan initiation during ADHF(inpatient) to initiation after ADHF(outpatient). (2) To explore the echocardiogram parameters associated with Sacubitril-Valsartan initiation during ADHF(inpatient) versus after ADHF(outpatient).

Methods

We enrolled patients diagnosed with heart failure with reduced ejection fraction (HFrEF) initiated on Sacubitril-Valsartan from February 2017 to December 2018. The baseline characteristics, echocardiogram parameters (changes in LVEF and positive remodeling), composite safety outcomes (hypotension, interruption of Sacubitril-Valsartan and worsening of renal function), and efficacy outcomes (cardiac death, readmission for heart failure) were compared.

Results

Thirty-seven patients were identified out of which 21 patients started Entresto after ADHF (outpatient group) and 16 patients during ADHF (inpatient group). The median follow-up duration was 196 days (IQR: 105 to 328days). The baseline characteristics were similar between the 2 groups. Outpatient groups achieved a significantly higher maximally tolerable dose of Sacubitril-Valsartan compared to inpatient group (median 400mg/day versus 200mg/day, p = 0.008) despite a similar starting dose (median 100mg/day versus 100mg/day, p = 0.127). The composite efficacy outcomes were similar between the 2 groups (4.8% versus 18.8%, p = 0.296). The composite safety outcome was similar between the groups (18.8% versus 4.8%, HR5.70 p = 0.054, 95%CI 0.967 to 33.60). Both groups achieved a significant improvement in LVEF after initiation of Sacubitril-Valsartan therapy: mean LVEF 23.44 ± 7.88% to 34.30 ± 13.88% (p = 0.001) in outpatient group; mean LVEF 22.99 ± 11.31% to 38.81 ± 13.91% (p = 0.002) in inpatient group. Reverse remodeling (reduction of LVESV≥15%) was similar between the 2 groups (61.9% versus 50.0%, p = 0.506).

Conclusions

Among patients with HFrEF in ADHF, initiation of Sacubitril-Valsartan therapy during or after ADHF led to similar safety and efficacy. Overall, there was a significant improvement in LVEF and positive remodeling of the LV regardless of the timing of initiation of therapy.

Modulator of apoptosis-1 is a potential therapeutic target in acute ischemic injury

Modulator of apoptosis 1 (MOAP-1) is a Bax-associating protein highly enriched in the brain. In this study, we examined the role of MOAP-1 in promoting ischemic injuries following a stroke by investigating the consequences of MOAP-1 overexpression or deficiency in in vitro and in vivo models of ischemic stroke. MOAP-1 overexpressing SH-SY5Y cells showed significantly lower cell viability following oxygen and glucose deprivation (OGD) treatment when compared to control cells. Consistently, MOAP-1^-/- primary cortical neurons were observed to be more resistant against OGD treatment than the MOAP-1^+/+ primary neurons. In the mouse transient middle cerebral artery occlusion (tMCAO) model, ischemia triggered MOAP-1/Bax association, suggested activation of the MOAP-1-dependent apoptotic cascade. MOAP-1^-/- mice were found to exhibit reduced neuronal loss and smaller infarct volume 24 h after tMCAO when compared to MOAP-1^+/+ mice. Correspondingly, MOAP-1^-/- mice also showed better integrity of neurological functions as demonstrated by their performance in the rotarod test. Therefore, both in vitro and in vivo data presented strongly support the conclusion that MOAP-1 is an important apoptotic modulator in ischemic injury. These results may suggest that a reduction of MOAP-1 function in the brain could be a potential therapeutic approach in the treatment of acute stroke.

Modulator of apoptosis 1 (MOAP-1) is a tumor suppressor protein linked to the RASSF1A protein

Modulator of apoptosis 1 (MOAP-1) is a BH3-like protein that plays key roles in cell death or apoptosis. It is an integral partner to the tumor suppressor protein, Ras association domain family 1A (RASSF1A), and functions to activate the Bcl-2 family pro-apoptotic protein Bax. Although RASSF1A is now considered a bona fide tumor suppressor protein, the role of MOAP-1 as a tumor suppressor protein has yet to be determined. In this study, we present several lines of evidence from cancer databases, immunoblotting of cancer cells, proliferation, and xenograft assays as well as DNA microarray analysis to demonstrate the role of MOAP-1 as a tumor suppressor protein. Frequent loss of MOAP-1 expression, in at least some cancers, appears to be attributed to mRNA down-regulation and the rapid proteasomal degradation of MOAP-1 that could be reversed utilizing the proteasome inhibitor MG132. Overexpression of MOAP-1 in several cancer cell lines resulted in reduced tumorigenesis and up-regulation of genes involved in cancer regulatory pathways that include apoptosis (p53, Fas, and MST1), DNA damage control (poly(ADP)-ribose polymerase and ataxia telangiectasia mutated), those within the cell metabolism (IR-α, IR-β, and AMP-activated protein kinase), and a stabilizing effect on microtubules. The loss of RASSF1A (an upstream regulator of MOAP-1) is one of the earliest detectable epigenetically silenced tumor suppressor proteins in cancer, and we speculate that the additional loss of function of MOAP-1 may be a second hit to functionally compromise the RASSF1A/MOAP-1 death receptor-dependent pathway and drive tumorigenesis.

Neuroimaging in refractory epilepsy. Current practice and evolving trends

Identification of the epileptogenic zone is of paramount importance in refractory epilepsy as the success of surgical treatment depends on complete resection of the epileptogenic zone. Imaging plays an important role in the locating and defining anatomic epileptogenic abnormalities in patients with medically refractory epilepsy. The aim of this article is to present an overview of the current MRI sequences used in epilepsy imaging with special emphasis of lesion seen in our practices. Optimisation of epilepsy imaging protocols are addressed and current trends in functional MRI sequences including MR spectroscopy, diffusion tensor imaging and fusion MR with PET and SPECT are discussed.

Magnetic Resonance Imaging of Asians with Multiple Sclerosis was Similar to that of the West

Magnetic resonance imaging (MRI) of the brain is the most important paraclinical diagnostic test in multiple sclerosis (MS). The appearance of MRI in Asians with MS is not well defined. We retrospectively surveyed the first brain and spinal cord MRI in patients diagnosed to have MS, according to Poser's criteria in seven regions throughout Asia to define the MRI changes among Asians with MS. There were 101 patients with first brain, and 86 with first spinal cord MRI, 66 of whom had both. The brain MRI showed a mean of 17 lesions per patient in T2 weighted images, mostly asymptomatic. Almost all the lesions were in the white matter, particularly in the juxtacortical, deep and periventricular white matter. A third of the lesions were greater than 5 mm, 14% enhanced with gadolinium. There were more supratentorial than infratentorial lesions at a ratio of 7.5: 1. Ninety five percent of the spinal cord lesions were in cervical and thoracic regions, 34% enhanced with gadolinium. The lesions extended over a mean of 3.6 +/- 3.3 vertebral bodies in length. Fifty (50%) of the brain and 54 (63%) of the spinal MRI patients had the optic-spinal form of MS. The MRI of the optic-spinal and classical groups of patients were similar in appearance and distribution, except that the optic-spinal MS patients have fewer brain but longer and more severe spinal cord lesions. In conclusion, the brain and spinal cord MRI of Asian patients with MS was similar to that of the West, although, in this study, Asian MS patients had larger spinal cord lesions.

Periodic lateralized epileptiform discharges (PLEDs) in cerebral lupus correlated with white-matter lesions in brain MRI and reduced cerebral blood flow in SPECT

This is a case report on an uncommon correlation between periodic lateralized epileptiform discharges (PLEDs) and white-matter lesions in cerebral lupus, and with a reduced cerebral blood flow (CBF) in single-photon emission computed tomography (SPECT). A 47-year-old woman with a long-term history of systemic lupus erythematosus (SLE) presented with a seizure followed by frontal lobe dysfunction clinically. An electroencephalogram (EEG) showed bilateral independent PLEDs in the frontal region. A magnetic resonance image of the brain showed white-matter changes in the frontal periventricular region. Cerebral angiogram did not reveal any evidence of vasculitis. A cerebral SPECT with tracer injected during the EEG showing PLEDs showed a reduction in CBF in the frontal regions. Clinical recovery was observed with intravenous immunoglobulin. This case shows that PLEDs can be seen with white-matter changes in SLE.

Clinical and pathological manifestations of human henipavirus infection

The clinicopathological features of human Nipah virus and Hendra virus infections appear to be similar. The clinical manifestations may be mild, but if severe, includes acute encephalitic and pulmonary syndromes with a high mortality. The pathological features in human acute henipavirus infections comprise vasculopathy (vasculitis, endothelial multinucleated syncytia, thrombosis), microinfarcts and parenchymal cell infection in the central nervous system, lung, kidney and other major organs. Viral inclusions, antigens, nucleocapsids and RNA are readily demonstrated in blood vessel wall and numerous types of parenchymal cells. Relapsing henipavirus encephalitis is a rare complication reported in less than 10% of survivors of the acute infection and appears to be distinct from the acute encephalitic syndrome. Pathological evidence suggests viral recrudescence confined to the central nervous system as the cause.

Lack of association of ABCB1 and PXR polymorphisms with response to treatment in epilepsy

It is proposed that overexpression of P-glycoprotein (P-gp), encoded by the ABC subfamily B member 1 (ABCB1) gene, is involved in resistance to antiepileptic drugs (AEDs) in about 30% of patients with epilepsy. Genetic variation and haplotype patterns are population specific which may cause different phenotypes such as response to AEDs. Although several studies examined the link between the common polymorphisms in the ABCB1 gene with resistance to AEDs, the results have been conflicting. This controversy may be caused by the effect of some confounders such as ethnicity and polytherapy. Moreover, expression of the ABCB1 gene is under the control of pregnane X receptor (PXR). Evidence showed that PXR gene contribute to the response to treatment. The aim of this study was to assess the association of ABCB1 and PXR genetic polymorphisms with response to the carbamazepine (CBZ) or sodium valproate (VPA) monotherapy in epilepsy. Genotypes were assessed in 685 Chinese, Indian, and Malay epilepsy patients for ABCB1 (C1236T, G2677T, C3435T) and PXR (G7635A) polymorphisms. No association between these polymorphisms and their haplotypes, and interaction between them, with response to treatment was observed in the overall group or in the Chinese, Indian, and Malay subgroups. Our data showed that these polymorphisms may not contribute to the response to CBZ or VPA monotherapy treatment in epilepsy.

Antioxidant Activities and Total Phenolic Content of Aqueous Extract of Pleurotus ostreatus (Cultivated Oyster Mushroom)

Pleurotus ostreatus better known as oyster mushroom is widely cultivated and consumed as food in Malaysia. The present study aims to assess the antioxidative potential and total phenolic content of P. ostreatus aqueous extract. The antioxidant activities were evaluated against DPPH and ABTS radical-scavenging activity, ferric-reducing antioxidant power (FRAP) and β-carotene-linoleate bleaching assay, and the Folin-Ciocalteu method for total phenolic content (TPC). The DPPH and ABTS radical-scavenging activity was found to be 63.20% and 87.29% respectively; antioxidant activity using FRAP at 1.45 mM FE/100g and β-carotenelinoleate bleaching assay was 83.51%, while the TPC was found to be 798.55 mg GAE/100g. These antioxidant activities were compared to synthetic antioxidant, BHA and ascorbic acid. Ascorbic acid showed highest scavenging effects on DPPH and ABTS radical, followed by P. ostreatus and BHA (at maximum safety limit). The ferric reducing power of P. ostreatus was significantly higher than BHA and ascorbic acid. The antioxidant activity as assessed in β-carotene-linoleate bleaching assay was found to be higher in BHA compared to P. ostreatus. The aqueous extract of P. ostreatus was found to respond differently in antioxidant assays. The antioxidative activity of the aqueous extract of P. ostreatus correlated with its total phenolic content. Generally, the antioxidant activities of P. ostreatus' aqueous extract are comparable to that of BHA and ascorbic acid to a certain extent.

ABCB1 C3435T polymorphism and the risk of resistance to antiepileptic drugs in epilepsy: a systematic review and meta-analysis

OBJECTIVE

The C3435T, a major allelic variant of the ABCB1 gene, is proposed to play a crucial role in drug-resistance in epilepsy. The C/C genotype carriers reportedly are at higher risk of pharmacoresistance to AEDs, but only in some studies. The hypothesis of the C-variant associated risk and resistance to antiepileptic drugs (AEDs) has been hampered by conflicting results from inadequate power in case-control studies. To assess the role of C3435T polymorphism in drug-resistance in epilepsy, a systematic review and meta-analysis was conducted.

METHODS

Databases were obtained from the Cochrane Library, MEDLINE, EMBASE, major American and European conference abstracts, and www.google.my for genetic association studies up to February 2010. All the case-control association studies evaluating the role of ABCB1 C3435T in pharmacoresistance to AEDs were identified. The new definition of treatment outcome from International League Against Epilepsy (ILAE) was used for including studies for sub-analysis. To measure the strength of genetic association for the gene variant, the odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using models of both fixed- and random-effects for comparisons of the alleles and genotypes with co-dominant (C/C vs. T/T, C/T vs. T/T), dominant (C/C+C/T vs. T/T), and recessive (C/C vs. C/T+T/T) models in overall and in ethnicity subgroups. The 19 studies were selected for the next sub-analysis based on the new definition of drug-responsiveness and drug-resistance from ILAE. The same analysis was also performed for treatment outcome and ethnicity subgroups.

RESULTS

A total of 22 association studies including 3231 (47.8%) drug-resistant patients and 3524 (52.2%) drug-responsive patients or healthy controls (genotyped for C3435T) were pooled in this meta-analysis. The allelic association of ABCB1 C3435T with risk of drug-resistance was not significant under fixed-effects model, 1.06 (95% CI 0.98-1.14, p=0.12) and random-effects model, 1.10 (0.93-1.30, p=0.28) in overall and in the subgroup analysis by ethnicity. Similar results were also obtained for all genetic models in the stratified analyses by new definition of drug-resistance by ILAE and ethnicity subgroups. There was no publication bias.

CONCLUSION

We failed to show an association between the ABCB1 C3435T polymorphism and the risk of drug-resistance suggesting a revision in contribution of this polymorphism in the multi-drug transporters hypothesis of pharmacoresistance to AEDs in epilepsy.

A review of multiple sclerosis with Asian perspective

Multiple sclerosis, although a rare disease in Asia, often presents significant diagnostic challenges to clinicians. There has been rapid advancement in the understanding of the underlying genetic influence, pathophysiology, investigation and treatment recently. This paper reviewed the latest development of various aspects of the disease and examined the differences between the manifestations of Asian and Western patients. The implications of these differences to investigation and treatment were also touched upon.

Rapid detection and serotyping of dengue virus by multiplex RT-PCR and real-time SYBR green RT-PCR

INTRODUCTION

Dengue fever and dengue haemorrhagic fever currently rank highly among the newly-emerging infectious diseases, and are considered to be the most important arboviral disease worldwide. The definitive diagnosis is culture analysis, but practical considerations limit its use. Also, the period for viral detection is limited. Within a day or two after fever subsides, rising levels of antibodies interfere with viral cultures. An alternative to this quandary is the use of viral RNA detection assays. In our laboratory, a reverse transcriptase polymerase chain reaction (RT-PCR) assay was developed using a set of degenerate primers.

METHODS

This multiplex RT-PCR assay was evaluated with 280 samples collected during the year 2003. These groups include prototype dengue virus (serotypes 1-4), acute serum from which the dengue virus was isolated, seronegative acute samples (culture negative) but whose convalescent samples seroconverted, and sera positive for other microbial diseases. This assay was then modified into a real-time SYBR Green RT-PCR assay. Sensitivity and specificity of both assays were compared.

RESULTS

The multiplex RT-PCR assay was able to detect 134 samples whereas SYBR Green RT-PCR assay was able to detect 178 out of 306 samples. Both assays were 100 percent specific. Further analysis of 53 samples showed that the virus could be amplified at IgM positive/negative values of up to 4.2, and up to six days after onset of fever. The viral detection rate was inversely proportional to the day of fever onset as well as IgM values.

CONCLUSION

The sensitivity and specificity of the conventional multiplex RT-PCR assay are 98.18 percent and 100 percent, respectively, and for the real-time SYBR Green assay, 99.09 percent and 100 percent, respectively. The melting curve analysis allows all four dengue serotypes to be discriminated based on distinct melting temperature value. The accuracy and speed of this multiplex RTPCR assay makes it a suitable test for the diagnosis of dengue and for epidemiological surveillance.

Cutaneous silent periods in the evaluation of cord compression in cervical spondylosis

OBJECTIVE

The clinical diagnosis of cervical spondylotic myelopathy (CSM) may be challenging in patients with cervical spondylosis (CS). Routine nerve conduction studies (NCS) may not evaluate cord compression adequately.

METHODS

We obtained cutaneous silent periods (CSP) in 26 consecutive patients presenting with clinical features of CS, in comparison with 30 normal controls. The results were also compared with transcranial magnetic stimulation (TMS) findings, and magnetic resonance imaging of the cervical cord as the gold standard.

RESULTS

CSP findings showed similarly high sensitivity of up to 96% with TMS in evaluating cervical cord dysfunction.

CONCLUSION

In specific clinical settings, CSP is of value for the diagnosis of CSM in CS. CSP measurement is advocated as a simple and rapid diagnostic adjunct to NCS in evaluating CS patients with possible cord compromise.

Intraoperative monitoring study of ipsilateral motor evoked potentials in scoliosis surgery

Ipsilateral motor evoked potentials (MEPs) in spinal cord surgery intraoperative monitoring is not well studied. We show that ipsilateral MEPs have significantly larger amplitudes and were elicited with lower stimulation intensities than contralateral MEPs. The possible underlying mechanisms are discussed based on current knowledge of corticospinal pathways. Ipsilateral MEPs may provide additional information on the integrity of descending motor tracts during spinal surgery monitoring.

Transcranial magnetic stimulation screening for cord compression in cervical spondylosis

OBJECTIVE

Cervical spondylosis (CS) often results in various degrees of cord compression, which can be evaluated functionally with transcranial magnetic stimulation (TMS). We investigate the use of TMS as a screening tool for myelopathy in CS.

METHODS

We prospectively studied 231 patients classified into Groups 1 to 4 based on MRI grading of severity of cord compromise. TMS elicited central motor conduction times and motor evoked potential (MEP) amplitudes in all 4 limbs. The results were compared with those from 45 healthy controls.

RESULTS

TMS showed 98% sensitivity and 98% specificity for cord abnormality using MRI as reference standard.

CONCLUSIONS

MEP abnormalities are useful for electrophysiological evaluation of cord compression in CS. While TMS is not a substitute for MRI, it is of value as a rapid, inexpensive and non-invasive technique for screening patients before MRI studies.

Pectoralis major motor evoked potentials in cervical spondylosis

Myelopathy is a severe complication of cervical spondylosis (CS). We studied 27 consecutive patients with CS referred for evaluation for possible myelopathy using transcranial magnetic stimulation. The findings were compared with those from 20 normal controls. Magnetic resonance imaging was utilized to assess the degree of cord compromise. Central motor conduction time (CMCT) abnormalities showed equivalent diagnostic yield with pectoralis major (PM) recordings, as compared with combined first dorsal interossei and abductor hallucis recordings. Our findings show that CMCT measurement with PM recordings is of value as a diagnostic adjunct in the electrophysiological evaluation of myelopathy in CS.

Candida spondylodiscitis and epidural abscess: management with shorter courses of anti-fungal therapy in combination with surgical debridement

Epidural abscess associated with candidal spondylodiscitis is rarely seen, particularly when it involves the cervical and thoracic spine. We report two such cases that were successfully managed with early surgical debridement, as well as medical therapy with intravenous amphotericin followed by oral fluconazole. The literature related to candidal spinal infection is reviewed, and a rational approach to the management of this uncommon condition is proposed. A good outcome may generally be expected with early diagnosis as well as appropriate surgical and pharmacological treatment. Oral fluconazole appears to be useful in the management of candida spondylodiscitis complicated by epidural abscess formation. Treatment until a normal ESR is attained is ideal, and this may be as short as 3 months when surgical drainage has been adequately performed.

Legal issues in the treatment of a violent manic patient in a non-gazetted setting: a case report

INTRODUCTION

Psychiatrists in non-gazetted treatment settings, like psychiatric wards in restructured general hospitals and private hospitals, face a major problem when psychiatric patients who require admission are either not competent or refuse to consent to admission and treatment, although they are clearly in need of such inpatient management. Admission to the state mental hospital is often refused by their relatives for a number of reasons, like the stigma attached to admission to such a hospital, and the fear that future employment prospects might be affected.

CLINICAL PICTURE

Mr X, a manic, violent patient, had no insight into his disorder and refused admission and treatment for his manic episode. He was the head of a large corporation, and his relatives were apprehensive he would make decisions that could jeopardize the company.

TREATMENT

He refused oral medication, could not tolerate parenteral haloperidol and had lithium nephrotoxicity. Inpatient electroconvulsive therapy had to be administered, after which he responded satisfactorily.

CONCLUSION

The legal implications in this case, like consent for treatment and admission, and ethical issues, are discussed.

Overriding fifth finger: an unusual sign in lower brachial plexopathy

Hand deformities are often useful clinical signs. To our knowledge, they have not been described in association with brachial plexus lesions. A 28-year-old female presented with sudden left shoulder pain and medial forearm parasthesia. Examination showed the left fifth finger adducting and flexing over the dorsal aspect of the fourth finger. Neurophysiological studies and MRI supported a brachial plexus lesion. The physical sign was not present 5 months post onset and the patient experienced near complete clinical improvement. The unusual physical sign occurred in association with neuralgic amyotrophy. Its occurrence can be explained in terms of transient patchy involvement of nerve fascicles in the brachial plexus.

Vacuum Electrolysis Reactor Technique for Quantitation of 13-Carbon Isotope Enrichment at the C1-Position of Formic Acid and Acetic Acid

A specialized vacuum electrolysis reactor was designed, constructed, and utilized for 13-carbon isotope analysis of formic acid-13C and acetic acid-13C, each highly enriched at the C1-position. This reusable reactor was equipped with two platinum wire electrodes, miniature stir bar, and sidearm reaction chamber. The associated technique developed for 13-carbon isotope analysis is based upon electrolytic generation of carbon dioxide into the preevacuated reactor followed by gas inlet mass spectrometry. It proved practical to degas and electrolyze 95% formic acid (without added electrolyte) due to adequate ionic conductivity. Formic acid-13C (nominally 99 at. % 13C) was measured by electrolytic CO2 generation to be 98.9 at. % 13C. To analyze various 13C-isotopic permutations of acetic acid, lithium and acid were separately added to reactor compartments, vacuum degassed, and stirred to produce an acidic solution. Thus, acetic acid-1-13C that was nominally 99 at. % 13C1 was determined by vacuum electrolysis to be 98.9 at. % 13C1. Further, acetic acid-2-13C that was isotope depleted at the C1-position (and known to be 99 at. % 13C at C2) gave 0.8 at. % 13C by mass spectrometry.

Systematic correlation of transcranial magnetic stimulation and magnetic resonance imaging in cervical spondylotic myelopathy

STUDY DESIGN

A prospective study over a 3.5-year period involving transcranial magnetic stimulation and magnetic resonance imaging.

OBJECTIVES

To assess the correlation of transcranial magnetic stimulation and magnetic resonance imaging in cervical spondylotic myelopathy qualitatively and statistically.

SUMMARY OF BACKGROUND DATA

Cervical spondylotic myelopathy presents with different degrees of cord compression, which can be assessed by magnetic resonance imaging. There are no large studies correlating transcranial magnetic stimulation and magnetic resonance imaging findings in this condition.

METHODS

A total of 141 patients with a clinical diagnosis of cervical spondylotic myelopathy were prospectively studied over a 3.5-year period. They were classified into Groups 1 to 4 based on severity of cervical cord changes on magnetic resonance imaging. All had transcranial magnetic stimulation and central motor conduction time measurements within 2 months of the magnetic resonance imaging study.

RESULTS

Twenty-eight, 49, 28, and 36 patients were classified into Groups 1 to 4, respectively. Mean upper limb and lower limb central motor conduction times correlated with the severity of magnetic resonance cord compression. The absence of central motor conduction time abnormalities correlated reliably with the absence of cervical cord impingement as in Group 1. Statistically significant right left difference in central motor conduction time in the lower limbs was seen between Groups 1 (no cord changes) and Group 2 (mild cord impingement). Eight other patients with diagnoses other than cervical spondylotic myelopathy all showed central motor conduction time abnormalities. The sensitivity and specificity for transcranial magnetic stimulation for differentiating the presence from absence of magnetic resonance imaging cord abnormality were 100% and 84.8%, respectively.

CONCLUSIONS

Transcranial magnetic stimulation showed excellent correlation with magnetic resonance imaging findings and can be considered as an effective technique for screening patients for cervical cord abnormalities before magnetic resonance imaging in the clinical setting. The findings in this study have relevant implications in the pathophysiology, management, and health costs of cervical spondylotic myelopathy.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) in a Chinese family: clinical, radiological and skin biopsy features

We describe the clinical, radiological, genetic and skin biopsy findings of the first Chinese family with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Of the 43-member family tree extending over three generations, eight had typical clinical features of CADASIL with recurrent ischemic stroke. In the three surviving affected family members, brain MRI showed extensive leukoaraiosis. Genotyping revealed heterozygous C to T mutation at nucleotide 406 in exon 3. Unusual clinical features were cerebellar infarction as a presenting complaint and a late age of onset with mild symptoms at age 69. A novel finding is the suggestion of a direct correlation between clinical disease severity and the quantity of ultrastructural pathognomonic granular osmophilic material (GOM) seen on skin biopsy.

Intra-operative monitoring in scoliosis surgery with multi-pulse cortical stimuli and desflurane anesthesia

STUDY DESIGN

Prospective, observational study.

SETTING

Country General Hospital, Singapore.

OBJECTIVE

Intraoperative monitoring (IOM) with motor-evoked potentials (MEPs) assesses the integrity of cortical spinal tracts during scoliosis surgery. MEPs are sensitive to the effects of inhalational anesthetic agents. We evaluate the use of desflurane in combination with multipulse cortical stimulation in this study.

METHODS

In all, 10 consecutive neurologically normal subjects underwent scoliosis surgery with desflurane anesthesia (0.5 maximum alveolar concentration) and five pulse cortical stimulation (250 Hz) from two stimulators in parallel configuration, delivering a maximum intensity of 160 mA.

RESULTS

Consistent MEPs were obtained from the abductor hallucis and tibialis anterior in nine of ten and five of five of subjects, respectively. Baseline coefficients of variations were below 16% for both muscles.

CONCLUSION

This combination of anesthetic and stimulation protocols is efficacious for IOM during spinal cord surgery. Our findings support the use of desflurane for successful acquisition of MEPs during scoliois surgery as an alternative anesthetic regime.

Nipah virus infection, an emerging paramyxoviral zoonosis

The Nipah virus outbreak represented one of several bat-derived paramyxoviruses that has emerged during the last decade to cause severe human and animal disease. The pathogenesis of Nipah infection is associated with its ability to infect blood vessels and extravascular parenchyma in many organs, particularly in the central nervous system. The clinical manifestations of acute Nipah infection range from fever and mild headache to a severe acute encephalitic syndrome in which there is a high mortality. Much remains to be understood about this new disease, including its intriguing ability to cause relapsing encephalitis in some survivors. This review provides an overview of the Nipah outbreak, focussing on what is presently known about it as an infectious disease, including the clinical aspects, pathology and pathogenesis.

Prevalence of peripheral artery disease in urban high-risk Malaysian patients

Atherosclerosis is a progressive, disseminated condition that affects all the vascular beds. Peripheral arterial disease (PAD), a manifestation of atherosclerosis, measured non-invasively in the legs by ankle-brachial index (ABI) is associated with increased cardiovascular morbidity and mortality. Though several studies in the western industrialised countries have shown that PAD is widely prevalent in the general older population at risk, not much data are available in the South East Asian developing countries. We have conducted an epidemiological survey on the prevalence of PAD in high-risk patients at an urban hospital in Malaysia. A total of 301 consecutive patients aged 32-90 years were recruited during their follow-up clinic visits for established cardiovascular disease, ischaemic stroke or diabetes mellitus > or = 5 years. All participants underwent ABI measurement and were subjected to the Edinburgh claudication questionnaire to assess leg symptoms. The prevalence of PAD in our high-risk population was 23%, of which only 27% were symptomatic with the classical intermittent claudication. All the patients with PAD were diagnosed at the time of the study. PAD was found in 33% of patients with pre-existent cardiovascular disease, 28% in patients with ischaemic stroke and 24% in diabetic patients. PAD was also highly prevalent among the younger patients. Our study has shown that PAD is highly prevalent among high-risk Malaysian patients and is not necessarily a disease of older age. Only 27% of these patients were symptomatic. All the subjects with PAD were diagnosed at the time of the study, which would suggest it is an unrecognised and underdiagnosed condition, even in patients with atherosclerotic risk factors.

Tensile properties, tension-tension fatigue and biological response of polyetheretherketone-hydroxyapatite composites for load-bearing orthopedic implants

Polyetheretherketone-hydroxyapatite composites were developed as alternative materials for load-bearing orthopedic applications. The amount of hydroxyapatite (HA) incorporated into the polyetheretherketone (PEEK) polymer matrix ranges from 5 to 40 vol% and these materials were successfully fabricated by injection molding. This study presents the mechanical and biological behavior of the composite materials developed. It was found that the amount of HA in the composite influenced the tensile properties. Dynamic behavior under tension-tension fatigue revealed that the fatigue-life of PEEK-HA composites were dependent on the HA content as well as the applied load. The biological responses of PEEK-HA composites carried out in vivo verified the biocompatibility and bioactive nature of the composite materials.

Nipah encephalitis outbreak in Malaysia

INTRODUCTION

Between September 1998 and June 1999, there was a severe outbreak of viral encephalitis among the pig farm workers in Malaysia.

METHODS

This is a review of the published literature related to the outbreak with the focus on human diseases.

RESULTS

The encephalitis was caused by a newly discovered paramyxovirus related to Hendra virus, later named Nipah virus. There were 265 patients with acute encephalitis. The disease is thought to spread from pig to man through close contact. The risk of human-to-human spread is thought to below. The disease affected mainly adult Chinese males, half of whom had affected family members. The disease presented mainly as acute encephalitis with a short incubation period of less than two weeks, with the main symptoms of fever, headache, and giddiness followed by coma. Distinctive clinical signs include segmental myoclonus, areflexia and hypotonia, hypertension, and tachycardia. Initial cerebrospinal fluid was abnormal in 75% of patients. Serology was helpful in confirming the diagnosis. Magnetic resonance imaging showed distinctive changes of multiple, discrete, and small high signal lesions, best seen with fluid-attenuated inversion recovery (FLAIR) sequences. Mortality was high at 40% and death was probably due to severe brainstem involvement. The main necropsy finding in acute encephalitis was that of disseminated microinfarction associated with vasculitis and direct neuronal involvement. Ribavirin was able to reduce the mortality by 36%. Relapse encephalitis was seen in 7.5% of those who recovered from acute encephalitis, and late-onset encephalitis in 3.4% of those with initial non-encephalitic or asymptomatic diseases. The mean interval between initial illness and the onset of the complication was 8.4 months. The relapse and late-onset encephalitis which manifested as focal encephalitis arose from recurrent infection.

CONCLUSION

Nipah virus, a recently discovered paramyxovirus, causes a unique encephalitis with high mortality as well as relapse and late-onset encephalitis. The infection is mainly spread from pigs to man.

Potentiation of noise-induced hearing loss by amikacin in guinea pigs

Noise and aminoglycosides initially attack cochlear outer hair cells (OHCs). Distortion product otoacoustic emissions (DPOAEs) are used for the early diagnosis of damage to OHCs. The effects of sub-damaging doses of amikacin, an aminoglycoside antibiotic agent, on noise-induced hearing loss (NIHL) were examined in guinea pigs. Animals were grouped by gender and exposed to broadband noise at 105 dB SPL for 12 h and/or injected i.m. with either amikacin (100 mg/kg/day) or saline for 10 days. Auditory brainstem response (ABR) thresholds, along with DPOAE amplitudes, were measured serially before and after noise exposure. DPOAE amplitudes decreased and ABR thresholds elevated immediately after noise exposure and then gradually recovered. At all frequencies, the emission amplitudes recovered completely to pre-exposure baseline values by 4 days after noise exposure. There was no effect of amikacin on either the ABR threshold or DPOAE amplitudes, in animals treated with amikacin only. However, amikacin significantly prolonged the effect of noise exposure on DPOAE amplitude but not on the noise-induced temporary threshold shift (TTS) of the ABR. In animals treated with a combination of noise and amikacin, significant changes in DPOAE amplitudes were still observed at 4 weeks after cessation of noise exposure. No gender difference in the responses to noise and/or amikacin could be demonstrated. The present findings indicate that even sub-damaging dosages of amikacin might impair recovery from NIHL in guinea pigs.

Auditory abnormalities associated with unilateral renal agenesis

OBJECTIVE

To evaluate the relationship between unilateral renal agenesis and auditory abnormality, and to determine the clinical spectrum of hearing impairment in such patients.

METHODS

Seventy-five children with unilateral renal agenesis underwent auditory examinations. The subjects comprised 35 males and 40 females. Fourteen females had mullerian abnormalities. Another 75 schoolchildren with the same gender profile were selected for audiometric testing as a control group. Children with sonographically evident urogenital system abnormalities were excluded from the control group.

RESULTS

The prevalence of auditory abnormalities in children with unilateral renal agenesis (4/75) (5.3%) was higher than in the control group (0%). The prevalence in children with urogenital anomalies was significantly higher in patients with renal agenesis than in the normal population (28.5%). Audiometric results showed that four of the 75 children manifested ipsilateral sensorineural hearing impairment, particularly in the high-frequency range. All were females with coexisting genital abnormalities. Two were diagnosed with mild sensorineural hearing impairment while the other two had moderate hearing loss.

CONCLUSIONS

The results of our study suggest that neurosensory hearing loss was found to be associated with renal agenesis. Further audiometric follow-up of children with renal agenesis seems worthwhile.

The Torg--Pavlov ratio in cervical spondylotic myelopathy: a comparative study between patients with cervical spondylotic myelopathy and a nonspondylotic, nonmyelopathic population

STUDY DESIGN

A radiologic study to compare the Torg--Pavlov ratios between patients with cervical spondylotic myelopathy and a nonspondylotic, nonmyelopathic population.

OBJECTIVES

To determine and compare the Torg--Pavlov ratios between the two groups of patients.

SUMMARY OF BACKGROUND DATA

Patients with congenital cervical spinal canal stenosis are more likely to develop cervical spondylotic myelopathy. The Torg--Pavlov ratio eliminates errors related to magnification, a problem with determination of spinal canal stenosis from direct measurements of plain cervical spine radiographs. There has only been one other study that directly compares the Torg--Pavlov ratio between patients with cervical spondylotic myelopathy and a normal control population.

METHODS

The preoperative plain lateral cervical spine radiographs of 28 patients with cervical spondylotic myelopathy requiring surgical decompression were compared with radiographs of 88 nonspondylotic, nonmyelopathic patients. The Torg--Pavlov ratio was computed for each level from C3 to C7.

RESULTS

The study showed that the Torg--Pavlov ratio is significantly smaller (P < 0.001) in myelopathic patients (mean 0.72 +/- 0.08) compared with the control patients (mean 0.95 +/- 0.14). This was so when individual levels and the mean values were compared. Age was also found to be a significant factor (P = 0.002), although lesser in magnitude when compared with the Torg--Pavlov ratio (P = 0.0001).

CONCLUSIONS

The Torg--Pavlov ratio is significantly lower in patients with cervical spondylotic myelopathy compared with a nonspondylotic, nonmyelopathic population. It could possibly be used to predict the likelihood of developing cervical spondylotic myelopathy.

Delayed post-irradiation bulbar palsy in nasopharyngeal carcinoma

In a hospital series of 70 patients on follow-up after radiotherapy for nasopharyngeal carcinoma, 14 patients (20%) developed delayed post-irradiation bulbar palsy 1 to 18 years after radiotherapy (mean 5.5 years). Functional disability was moderate to severe. Three patients had aspiration pneumonia with one mortality. Post-irradiation bulbar palsy was a common complication and probably resulted from direct neuronal damage.

Na+,K+-ATPase and Ca2+-ATPase activities in the cochlear lateral wall following surgical induction of hydrops

Na+,K+-ATPase and Ca2+-ATPase activities have not been studied quantitatively in the cochlea affected by endolymphatic hydrops. The present study was designed to measure quantitatively the Na+,K+-ATPase and Ca2+-ATPase activities in the cochlear lateral wall and the threshold of auditory brainstem response (ABR) for guinea pigs in the early stages (=2 months) of experimentally induced endolymphatic hydrops. A significant negative association was demonstrated between Ca2+-ATPase activity and the change in ABR threshold for hydropic cochleae (P=0.014), but not for control cochleae (P=0.123), although no such significant association was revealed between Na+,K+-ATPase activity and any change in ABR threshold for both hydropic cochleae (P=0.751) and control cochleae (P=0.352). A significant increase in Ca2+-ATPase activity in the cochlear lateral wall was observed for the hydropic ear, in which normal ABR thresholds were maintained, as compared to the control ear. On the contrary, a mild decrease in Ca2+-ATPase activity in the cochlear lateral wall was observed for the hydropic ear, in which ABR thresholds increased significantly. The present findings suggest that alterations of Ca2+-ATPase activity in the cochlear lateral wall may implicate disturbed calcium-homeostasis in the inner ear, resulting in hearing dysfunction in the early stages of experimentally induced endolymphatic hydrops.

Treatment of acute Nipah encephalitis with ribavirin

Nipah virus, a newly identified paramyxovirus caused a severe outbreak of encephalitis in Malaysia with high fatalities. We report an open-label trial of ribavirin in 140 patients, with 54 patients who were managed prior to the availability of ribavirin or refused treatment as control. There were 45 deaths (32%) in the ribavirin arm; 29 deaths (54%) occurred in the control arm. This represents a 36% reduction in mortality (p = 0.011). There was no associated serious side effect. This study suggests that ribavirin is able to reduce the mortality of acute Nipah encephalitis.

Effects of gentamicin and pH on [Ca2+]i in apical and basal outer hair cells from guinea pigs

Aminoglycosides are widely used antibiotics and frequently produce acute ototoxicity. In this study we attempted to comparatively investigate the effects of gentamicin on Ca2+ influx of apical and basal outer hair cells (OHCs) isolated from guinea-pig cochlea. Since the solution of gentamicin sulfate salt is acidic (pH 3.1-3.3), we also explored the effect of external acidification on Ca2+ influx. By means of fura-2 microspectrofluorimetry, we measured the intracellular calcium concentration ([Ca2+]i) of OHCs bathed in Hanks' balanced salt solution (pH 7.40) during either a resting state or high K+-induced depolarization. Our results show that at the resting state, the baseline [Ca2+]i in apical OHCs (94+/-2.0 nM) was slightly lower than that in basal OHCs (101.1+/-2.4 nM). By contrast, the increase in [Ca2+]i evoked by high K+ depolarization in apical OHCs was about two-fold greater than that in basal OHCs. Nifedipine (30 microM) abolished the increased [Ca2+]i in both types of OHCs, suggesting that Ca2+ influx was mainly through L-type Ca2+ channels of OHCs. While gentamicin and extracellular acidification (pH 7.14) can separately attenuate this increase in [Ca2+]i in both types of OHCs, their suppressive effects are additive in basal OHCs, but not in apical OHCs. The implications of these findings are that: (1) apical and basal OHCs behave differently in response to depolarization-increased [Ca2+]i, and (2) basal OHCs are more vulnerable to the impairment of Ca2+ entry during depolarization by a combination of gentamicin and extracellular acidification, which is correlated with the clinical observation that ototoxicity of aminoglycosides at the basal coil of OHCs is more severe than that at the apical coils. Moreover, the possibility that extracellular acidification may enhance the acute ototoxic effects of aminoglycosides should be considered especially in topical applications.