Transgenic mice overexpressing mutant TDP-43 show aberrant splicing of neurological disorders-associated gene Zmynd11 prior to onset of motor symptoms

Mutations in TDP-43 are known to cause Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD). TDP-43 binds to and regulates splicing of several RNA including Zmynd11 . Zmynd11 is a transcriptional repressor and a potential E3 ubiquitin ligase family member, known for its role in neuron and muscle differentiation. Mutations in Zmynd11 have been associated with autism with significant developmental motor delays, intellectual disability, and ataxia. Here, we show that Zmynd11 is aberrantly spliced in the brain and spinal cord of transgenic mice overexpressing a mutant human TDP-43 (A315T), and that these changes occur before the onset of motor symptoms.

Changing Demographics of Stroke Mimics in Present Day Stroke Code Era: Need of a Streamlined Clinical Assessment for Emergency Physicians

Background  There is an apparently high incidence of stroke mimics in the present-day stroke code era. The reason being is the intense pressure to run with time to achieve the “time is brain”-based goals.

Methods  The present study was a retrospective analysis of the data collected over a duration of 6 months from April 2019 to September 2019. We observed the incidence of stroke mimics among the patients for whom rapid response stroke code was activated during the study period. We also performed a logistic regression analysis to identify the clinical features which can act as strong predictors of stroke and mimics.

Results  A total of 314 stroke codes were activated of which 256 (81.5%) were stroke and 58 (18.5%) were the mimics. Functional disorders and epilepsy were the most common mimics (24.1% each). Female gender ( p = 0.04; odds ratio [OR] 2.9[1.0–8.8]), isolated impairment of consciousness ( p < 0.01; OR 4.3[1.5–12.6]), and isolated dysarthria ( p < 0.001) were the strong independent predictors for a stroke mimic. Hemiparesis was the strong independent predictor for a stroke ( p < 0.001; OR 0.0[0.0–0.1]).

Conclusion  In the present epoch of rapid response stroke management, a streamlined assessment by the emergency physicians based on the above clinical predictors may help in avoiding the misdiagnosis of a mimic as stroke.

Lessons Learned from a Fulminant Case of Reversible Cerebral Vasoconstriction Syndrome: Past Medical History Misleads the Diagnosis and Intra-Arterial Milrinone Offers Diagnostic Utility

A 34-year-old post-partum female having dermatomyositis developed headache and became comatose after a seizure episode. Magnetic resonance imaging of brain showed a massive left ganglio-capsular bleed for which decompressive surgery was done. Computed tomographic angiography showed multiple foci of narrowing and irregularities in distal cerebral vessels. In view of dermatomyositis, the diagnosis of vasculitis was considered and pulse therapy of intravenous methylprednisolone was started. The patient, however, showed no improvement and developed new brain infarcts. She was subsequently taken up for a diagnostic cerebral angiography which showed multifocal severe narrowing in bilateral major cerebral arteries. These angiographic abnormalities showed excellent reversibility to intra-arterial milrinone and hence, reversible cerebral vasoconstriction syndrome (RCVS) was diagnosed. Normal angiographic findings in the first week do not rule out the disease and a repeat angiography should be considered if the clinical suspicion of the RCVS is high. Intra-arterial milrinone has a high diagnostic utility.

High Prevalence of Asymptomatic Anterior Tarsal Tunnel Syndrome in Toddy Tappers of South India: A Case Series of 21 Participants

Background   Anterior tarsal tunnel syndrome (ATTS) is an uncommon entrapment neuropathy which occurs due to the compression of deep peroneal nerve under the inferior extensor retinaculum at the ankle. We observed a frequent occurrence of this syndrome in toddy palm tappers and hence, planned to study the association between the two.

Materials and Methods   We studied the prevalence of isolated deep peroneal neuropathy at the ankle among the asymptomatic toddy tappers enrolled over a period of 3 months.

Results   In our case series, 81% (17/21) of the study participants had ATTS of which 43% (9/21) had unilateral and 38% (8/21) had bilateral involvement. There was a strong inverse association (p < 0.001) of “duration of toddy tapping in years” with peroneal (extensor digitorum brevis) amplitudes on both the sides.

Conclusion   Our study confirms “palm tree climbing” to be an occupational etiology of ATTS.

Acute ischemic stroke thrombolysis with tenecteplase: An institutional experience from South India

Objective:

Outcome assessment of intravenous (IV) thrombolysis with tenecteplase in acute ischemic stroke.

Materials and Methods:

We consecutively enrolled acute ischemic stroke patients who underwent IV thrombolysis with tenecteplase from October 2016 to May 2017. Primary clinical efficacy outcome was defined as an improvement in the National Institute of Health Stroke Scale (NIHSS) score of ≥4 points at 24 h (h). Secondary clinical efficacy outcome was the favorable outcome on modified Rankin scale at 90 days defined as a score of 0 or 1. The safety endpoints were death rate at 90 days and symptomatic intracranial hemorrhage (SICH).

Results:

Mean NIHSS scores at baseline and 24 h were 13 (±3.81) and 9.29 (±5.74), respectively, the difference being statistically significant (P = 0.016). In this study, nine patients (64%) met the primary clinical efficacy outcome and eleven (78.5%) patients met the secondary clinical efficacy outcome. Only 1 (7%) patient developed SICH and additionally, aspiration pneumonia with subsequent death.

Conclusion:

This study confirms the efficacy and safety of tenecteplase for stroke thrombolysis in our clinical setting. Tenecteplase appears to be a suitable option for stroke thrombolysis in resource-limited settings, considering its cost-effectiveness, and ease of administration.

Prevalence of vitamin D deficiency in chronic and subacute low back pain patients in India: a triple-arm controlled study

Vitamin D is vital for musculoskeletal health and may be associated with subacute and chronic low back pain. The objective of this study was to estimate the prevalence of vitamin D deficiency among chronic low back pain (CLBP) and subacute low back pain (SLBP), and compare the same with healthy controls. This study was designed as triple-arm case-control study comprising of CLBP, SLBP, and controls. SLBP and CLBP cases were consecutively enrolled over 3 months of winter season from November 2016 to January 2017. Serum 25- (OH) vitamin D was estimated for the study subjects and categorical comparison of severity of vitamin D deficiency was done for the cases and controls. A total of 250 CLBP, 177 SLBP cases, and 248 controls were included in the study. Mean (± SD) serum vitamin D levels among CLBP, SLBP, and controls were 20.36 (± 12.56), 21.42 (± 13.20), and 20.84 (± 6.93) ng/ml respectively, the difference being statistically insignificant. There was no significant difference in the prevalence of vitamin D deficiency among CLBP, SLBP, and controls which was 53.6, 50.8, and 51.6% respectively, in the three arms. However, the categorical analysis revealed that CLBP and SLBP cases had a significantly higher prevalence of worse categories of vitamin D deficiency. Cases had significantly larger frequency (CLBP vs. controls, 43.6 vs 20.1%, P<0.001; SLBP vs. controls, 43.5 vs 20.1%, P = 0.001) of individuals with vitamin D levels ≤ 16 ng/ml (moderate deficiency upper threshold level). Thus, the severe forms of vitamin D deficiency may be causally associated with CLBP and SLBP. The results of the present study revealed that increasing severity of vitamin D deficiency may have a pathogenetic association with chronic low back pain and subacute low back pain. These results may prove to be of significance in framing of future management guidelines for the above clinical conditions.

A Comparison of the Intracerebral Hemorrhage Score and the Acute Physiology and Chronic Health Evaluation II Score for 30-Day Mortality Prediction in Spontaneous Intracerebral Hemorrhage

BACKGROUND

The intracerebral hemorrhage (ICH) score is well established as a reliable prognostic score in ICH, whereas recently, Acute Physiology and Chronic Health Evaluation II (APACHE II) has been observed to have a better discrimination in predicting mortality in primary pontine hemorrhage. Further, physiological parameters of APACHE II have been associated with outcome in ICH. This study is the first to observe a direct comparison between APACHE II and ICH scores in predicting 30-day mortality in spontaneous intracerebral hemorrhage (SICH).

MATERIALS AND METHODS

This study was a prospective observational study where we compared the receiver operating characteristic (ROCs) of baseline ICH and APACHE II scores in patients with SICH for predicting 30-day mortality outcome.

RESULTS

We observed that both APACHE II and ICH scores were good for predicting 30-day mortality with both having an area under the ROC curve of more than .8 (.831 [95% confidence interval {CI}, .740-.922; P <.001] and .892 [95% CI, .757-.932; P <.001], respectively). However, the ICH score was better discriminative (area under the curve AUC, .892 versus .831; P = .040) and better calibrated (P = .037 versus P = .089, Hosmer-Lemeshow goodness-of-fit test for logistic regression) for the same. Both APACHE II and ICH scores had a sensitivity of 87% at cutoff values of 19 and 3, respectively; however, the ICH score had a better specificity (90% versus 76.5%).

CONCLUSION

The ICH score was observed to have a better discrimination and calibration for predicting 30-day mortality in SICH.

Reply #2 to: Glycemic Choreoballism

In Response To: Lee D, Ahn, TB. Glycemic choreoballism. Tremor Other Hyperkinet Mov. 2016; 6. doi: 10.7916/D8QJ7HNF Original Article: Roy U, Das SK, Mukherjee A, et al. Irreversible hemichoreahemiballism in a case of nonketotic hyperglycemia presenting as the initial manifestation of diabetes mellitus. Tremor Other Hyperkinet Mov. 2016; 6. doi: 10.7916/D8QZ2B3F.

Effect of CPAP Therapy in Improving Daytime Sleepiness in Indian Patients with Moderate and Severe OSA

INTRODUCTION

Obstructive Sleep Apnoea (OSA) is a highly prevalent disease and a major public health issue in India. Excessive daytime sleepiness is an almost ubiquitous symptom of OSA. Epworth Sleepiness Scale (ESS) score is a validated objective score to measure the degree of daytime sleepiness. Continuous Positive Airway Pressure (CPAP) therapy has been established as the gold standard treatment modality for OSA patients. A few Indian studies have reported the effectiveness of CPAP therapy in improving ESS scores after 1^st month of CPAP use.

AIM

To observe both, short-term (one month) and long-term (three month) effects of CPAP therapy on ESS scores in moderate to severe OSA patients.

MATERIALS AND METHODS

The patients complaining of excessive day-time sleepiness, snoring and choking episodes during sleep, consecutively presenting to medicine OPD over a period of 2 years, were subjected to Polysomnography (PSG). Seventy-three patients with apnoea-hypopnea index (AHI) ≥15 were categorised as having moderate to severe forms of OSA (moderate OSA with AHI=15-30 and severe OSA with AHI >30), and were scheduled for an initial trial of CPAP therapy. Forty-seven patients reported good tolerance to CPAP therapy after a trial period of 2 weeks and comprised the final study group. ESS scores in these patients were recorded at the baseline, and after 1^st and 3^rd month of CPAP therapy, and statistically analysed for significance.

RESULTS

Mean ESS score at the baseline among moderate and severe OSA patients were 13.67±2.29 and 16.56 ±1.87, respectively. ESS score in both these subgroups improved significantly to 11.63±3.79, p=0.022, CI (0.3293-4.0106)} and 14.13 ±3.74, p < 0.001, CI (1.2991-4.5408), respectively after one month of CPAP therapy. Likewise, mean ESS scores among moderate and severe OSA patients improved significantly to 9.84 ±2.97, p = 0.022, CI (0.3293-4.0106) and 12.29 ±3.97, p <0.001, CI (2.9414-6.1385), respectively after three months of CPAP therapy.

CONCLUSION

The result of the present study shows that CPAP therapy is significantly effective in improving ESS scores in Indian patients having moderate to severe OSA. Benefits in daytime sleepiness were observed after short-term as well as long-term use of CPAP therapy.

Irreversible Hemichorea-Hemiballism in a Case of Nonketotic Hyperglycemia Presenting as the Initial Manifestation of Diabetes Mellitus

Background

Hemichorea–hemiballism (HCHB) is a hyperkinetic movement disorder with features of both chorea and ballism occurring on the same side.

Case report

We present a case of HCHB due to nonketotic hyperglycemia (NKH) that was the initial presentation of diabetes and was irreversible clinically even after 6 months of optimal blood sugar control.

Discussion

Although HCHB due to hyperglycemia is a potentially reversible condition in the majority of patients, prolonged uncontrolled hyperglycemia may cause ischemic insult and persistent symptoms. Hyperglycemia should always be kept in the list of differentials while dealing with patients who are newly diagnosed with HCHB.

Evaluation of the Serum Levels of Nitric Oxide among Diabetic Patients and its Correlation with Lipid Profile as well as Oxidative Stress in North Indian Setting

INTRODUCTION

Diabetes mellitus is a disease with a rapidly increasing prevalence, needs continue research for novel methods to both prevent and treat this disorder. Obesity and decreased physical activity are the major risk factor for the development of diabetes. Recently the emphasis is focused on oxidative stress in pathogenesis of this disease.

AIM

To assess the serum levels of Nitric Oxide (NO) among diabetic patients and its correlation with lipid profile as well as oxidative stress in north Indian setting.

MATERIALS AND METHODS

This was a cross-sectional study. Subjects suffering from type 2 diabetes for more than 1 year and age between 30 to 50 years with hyperuricaemia were included in the study. The patients were divided into three groups: Group I- Type 2 diabetics with dyslipidemia and hyperuricaemia, Group II- Type 2 diabetics with dyslipidemia and normouricaemia and Group III- Type 2 diabetics with normolipidemia and normouricaemia.

RESULTS

The nitric oxide level was significantly lower in Group I and Group II than Group III. The oxidative stress parameters had poor correlation with NO level in all the groups.

CONCLUSION

Our data suggests that there is definite role of Nitric Oxide (NO) in pathogenesis of type -2 diabetes mellitus with dyslipidemia and hyperuricaemia.

Clinical and Neuroradiological Spectrum of Metronidazole Induced Encephalopathy: Our Experience and the Review of Literature

Metronidazole is an antimicrobial agent mainly used in the treatment of several protozoal and anaerobic infections, additionally, is often used in hepatic encephalopathy and Crohn disease. Apart from peripheral neuropathy, metronidazole can also cause symptoms of central nervous system dysfunction like ataxic gait, dysarthria, seizures, and encephalopathy which may result from both short term and chronic use of this drug and is collectively termed as "metronidazole induced encephalopathy"(MIE). Neuroimaging forms the backbone in clinching the diagnosis of this uncommon entity, especially in cases where there is high index of suspicion of intoxication. Although typical sites of involvement include cerebellum, brain stem and corpus callosum, however, lesions of other sites have also been reported. Once diagnosed, resolution of findings on Magnetic Resonance Imaging (MRI) of the Brain along with clinical improvement remains the mainstay of monitoring. Here we review the key clinical features and MRI findings of MIE as reported in medical literature. We also analyze implication of use of this drug in special situations like hepatic encephalopathy and brain abscess and discuss our experience regarding this entity.

"Reverse Tigroid" Pattern in Pachygyria: A Novel Finding

Pachygyria is considered a subtype of lissencephaly which, in turn, is a spectrum of disorders caused by abnormal neuronal migration. Clinical presentation in this disorder may be varied including microcephaly, developmental delay, facial dysmorphism, seizures, and mental retardation. Magnetic resonance imaging (MRI) of brain identifies the exact nature and extent of the disease and helps in delineating further plan of management. A Tigroid pattern on axial MRI scan and leopard pattern on a sagittal plane has been classically reported in disorders of myelin formation such as metachromatic leukodystrophy and Pelizaeus–Merzbacher disease. We present here a case of pachygyria who presented to us with some atypical features including “tigroid-like stripes” and “leopard-like pattern” on MRI brain which has not been reported in the medical literature previously.

Neuromyelitis Optica Spectrum Disorder with Tumefactive Demyelination mimicking Multiple Sclerosis: A Rare Case

Neuromyelitis optica spectrum disorder (NMOSD) is a diverse condition which not only encompasses isolated longitudinally extensive transverse myelitis (LETM) and optic neuritis but also includes area postrema syndrome, acute brainstem syndrome, symptomatic narcolepsy or acute diencephalic clinical syndrome, and symptomatic cerebral syndrome. Imaging may reveal periependymal lesions surrounding the ventricular system or involvement of corticospinal tracts, area postrema, diencephalon, and corpus callosum. Rarely, there may be hemispheric tumefactive lesions that enhance in a "Cloud-like" fashion on gadolinium injection unlike in tumefactive multiple sclerosis where there is incomplete ring enhancement. Here, we present a case of aquaporin-4 positive relapsing NMOSD who presented to us with recurrent episodes of paraparesis with LETM and tumefactive lesions of brain on imaging, which enhanced in an incomplete ring like pattern resembling multiple sclerosis.

25-Hydroxy Vitamin D, Vitamin D Receptor and Toll-like Receptor 2 Polymorphisms in Spinal Tuberculosis: A Case-Control Study

Vitamin D deficiency and vitamin D receptor (VDR) gene abnormalities confer susceptibility to tuberculosis. Toll-like receptors (TLRs), such asTLR-2, are also important mediators of inflammatory response against Mycobacterium tuberculosis. We evaluated serum vitamin D, and VDR and TLR-2 gene polymorphisms in patients with spinal tuberculosis.This study comprised of 3 groups: spinal tuberculosis, pulmonary tuberculosis, and controls (each with 106 subjects). Enzyme-linked immunosorbent assay was used to measure vitamin D levels, and polymerase chain reaction-sequencing method was used to analyze VDR and TLR-2 gene polymorphisms. Patients were followed up for 6 months.Vitamin D deficiency was significantly more prevalent in patients with spinal tuberculosis (P < 0.001) and pulmonary tuberculosis (P = 0.011), versus controls. The heterozygous and mutant genotypes of VDR TaqI gene were significantly associated with spinal tuberculosis (P < 0.001; odds ratio [OR] 4.74 [2.45-9.18]) and pulmonary tuberculosis (P < 0.001; OR 3.52 [1.80-6.88]) when compared with controls. The heterozygous and mutant variants of VDR ApaI gene were significantly more common in patients with spinal tuberculosis in comparison with patients with pulmonary tuberculosis (P < 0.001; OR 2.90 [1.65-5.10]) and controls (P < 0.001; OR 6.56 [3.41-12.61]). We did not observe any significantly different results for TLR-2 gene polymorphisms. Vitamin D deficiency, VDR, and TLR-2 polymorphisms did not affect the 6-month disability.Vitamin D deficiency and VDR gene polymorphisms are significantly more prevalent in people with pulmonary and spinal tuberculosis. They may, in isolation or collectively, confer susceptibility to pulmonary and spinal tuberculosis.

Japanese Encephalitis Complicated with Obstructive Hydrocephalus

Japanese Encephalitis (JE), caused by Japanese encephalitis virus (JEV), a flavi-virus, is the most significant aetiology of arboviral encephalitis worldwide. It has resulted in epidemics of encephalitis in the Indian subcontinent. Here, we report a case of 36-year-old female who presented with a short history of fever and headache followed by altered sensorium. Funduscopic examination revealed Papilloedema. Pyogenic or viral meningoencephalitis along with complicated malaria were kept as initial differential diagnosis. Magnetic Resonance Imaging (MRI) of brain revealed involvement of posterior limb of internal capsule and bilateral thalami in the form of haemorrhagic encephalitis along with obstructive hydrocephalus. Cerebro Spinal Fluid (CSF) serology (IgM ELISA) showed JE as the causative agent. Despite extensive literature search, we could not find a case of JE reported with hydrocephalus as a complication. This case highlights the typical and atypical features of JE including imaging findings and exemplifies the way, how diversely JE can present and would thus help in preparing management paradigms accordingly.

Adult Presentation of Dyke-Davidoff-Masson Syndrome: A Case Report

Dyke-Davidoff-Masson syndrome (DDMS) is a rare disease which is clinically characterized by hemiparesis, seizures, facial asymmetry, and mental retardation. The classical radiological findings are cerebral hemiatrophy, calvarial thickening, and hyperpneumatization of the frontal sinuses. This disease is a rare entity, and it mainly presents in childhood. Adult presentation of DDMS is unusual and has been rarely reported in the medical literature.

Dystonia, myoclonus, and encephalopathy in a single patient: A rare association of moyamoya

Moyamoya disease (MMD) is a rare neurovascular disorder which pathologically, is a chronic cerebrovasculopathy. It is characterized by stenosis of the internal carotid artery (ICA) and the main branches within the circle of Willis with consecutive development of collateral vessels. There are a few cases in the literature which have described movement disorders as a manifestation of MMD; however these have been uncommonly reported in cases of moyamoya syndrome (MMS). We present a 10-year-old boy with dystonia, myoclonus and encephalopathy like features. These features in association with moyamoya, are rarely described.

Pontine Infarct Presenting with Atypical Dental Pain: A Case Report

Orofacial pain' most commonly occurs due to dental causes like caries, gingivitis or periodontitis. Other common causes of 'orofacial pain' are sinusitis, temporomandibular joint(TMJ) dysfunction, otitis externa, tension headache and migraine. In some patients, the etiology of 'orofacial pain' remains undetected despite optimal evaluation. A few patients in the practice of clinical dentistry presents with dental pain without any identifiable dental etiology. Such patients are classified under the category of 'atypical odontalgia'. 'Atypical odontalgia' is reported to be prevalent in 2.1% of the individuals. 'Atypical orofacial pain' and 'atypical odontalgia' can result from the neurological diseases like multiple sclerosis, trigeminal neuralgia and herpes infection. Trigeminal neuralgia has been frequently documented as a cause of 'atypical orofacial pain' and 'atypical odontalgia'. There are a few isolated case reports of acute pontine stroke resulting in 'atypical orofacial pain' and 'atypical odontalgia'. However, pontine stroke as a cause of atypical odontalgia is limited to only a few cases, hence prevalence is not established. This case is one, where a patient presented with acute onset atypical dental pain with no identifiable dental etiology, further diagnosed as an acute pontine infarct on neuroimaging. A 40 years old male presented with acute onset, diffuse teeth pain on right side. Dental examination was normal. Magnetic resonance imaging(MRI) of the brain had an acute infarct in right pons near the trigeminal root entry zone(REZ). Pontine infarct presenting with dental pain as a manifestation of trigeminal neuropathy, has rarely been reported previously. This stresses on the importance of neuroradiology in evaluation of atypical cases of dental pain.

Segmental neuromyotonia

Unilateral focal neuromyotonia has been rarely reported in fingers or extraocular muscles. We report a case of segmental neuromyotonia in a 20-year-old boy who presented to us with intermittent tightness in right upper limb. Electromyography revealed myokymic and neuromyotonic discharges in proximal as well as distal muscles of the right upper limb. Patient's symptoms responded well to phenytoin therapy. Such an atypical involvement of two contiguous areas of a single limb in neuromyotonia has not been reported previously. Awareness of such an atypical presentation of the disease can be important in timely diagnosis and treatment of a patient.

Glycaemic status is an important risk factor for the occurrence of diabetic retinopathy in newly diagnosed type 2 diabetic patients

Objective: To assess the frequency of diabetic retinopathy (DR) and correlation with HbA1C in newly diagnosed type 2 diabetic patients. Patients and research methods: The study was conducted at a tertiary care medical centre in north india.All patients of  >30 to <60 years of age, who were newly(within a month) diagnosed type 2 diabetes mellitus, according to world health organization(WHO)criteria and american diabetes association(ADA) recommendations,were included in the study. HbA1C was estimated from venous blood collected in ethylene diamine tetra acetic acid(EDTA) test tube, using  boronate affinity chromatography (HPLC).Diabetic retinopathy was assessed by fundus examination using  direct ophthalmoscope after dilatation of pupils.Early treatment diabetic retinopathy study(ETDRS) scale was used to assess the severity of diabetic retinopathy. Results: 28 % of the newly diagnosed cases were found to have diabetic retinopathy, of which 73.52% were of mild NPDR (non-proliferative diabetic retinopathy) and 26.47% were of moderate NPDR. Mean FPG of population with retinopathy was 194.05 ±29.82 mg/dl and that of population without retinopathy was 175.67 ± 27.71mg/dl. Mean HbA1C of population with retinopathy was 7.71±1.01%and that of population without retinopathy was 7.22 ± 0.74. Conclusions: Mild NPDR is the most common form of diabetic retinopathy in newly diagnosed type 2 DM patients. Study demonstrated a very significant positive correlation between level of glycosylated hemoglobin (HbA1C) and frequency of diabetic retinopathy in these cases. So, glycaemic status is an important risk factor for the occurrence of diabetic retinopathy.DOI: http://dx.doi.org/10.3126/ajms.v6i4.11745 Asian Journal of Medical Sciences Vol.6(4) 2015 36-39 

The COMT Val158 allele is associated with impaired delayed-match-to-sample performance in ADHD

Background

This study explored the association between three measures of working memory ability and genetic variation in a range of catecholamine genes in a sample of children with ADHD.

Methods

One hundred and eighteen children with ADHD performed three working memory measures taken from the CANTAB battery (Spatial Span, Delayed-match-to-sample, and Spatial Working Memory). Associations between performance on working memory measures and allelic variation in catecholamine genes (including those for the noradrenaline transporter [NET1], the dopamine D4 and D2 receptor genes [DRD4; DRD2], the gene encoding dopamine beta hydroxylase [DBH] and catechol-O-methyl transferase [COMT]) were investigated using regression models that controlled for age, IQ, gender and medication status on the day of test.

Results

Significant associations were found between performance on the delayed-match-to-sample task and COMT genotype. More specifically, val/val homozygotes produced significantly more errors than did children who carried a least one met allele. There were no further associations between allelic variants and performance across the other working memory tasks.

Conclusions

The working memory measures employed in the present study differed in the degree to which accurate task performance depended upon either the dynamic updating and/or manipulation of items in working memory, as in the spatial span and spatial working memory tasks, or upon the stable maintenance of representations, as in the delay-match–to-sample task. The results are interpreted as evidence of a relationship between tonic dopamine levels associated with the met COMT allele and the maintenance of stable working memory representations required to perform the delayed-match-to-sample-task.

A polystyrene based membrane electrode for cadmium(II) ions

A polystyrene based membrane of 3,4:12,13-dibenzo-2,5,11,14-tetraoxo- 1,6,10,15-tetraazacyclooctade-cane shows a Nernstian response to Cd(II) ions over a wide concentration range (3.16 x 10(-6) - 1.00 x 10(-1) mol L(-1) with a Nernstian slope of 29.8 mV/decade of concentration, between pH 2.0 and 6.0. This electrode has been found to be chemically inert and of adequate stability with a response time of 20s. The electrode gives reproducible results with a lifetime of 130 days. The membrane works satisfactorily in a partially non-aqueous medium up to a maximum 35% (v/v) content of methanol and ethanol. The practical utility of the proposed chemical sensor has been observed by using it as end-point indicator in the titration of Cd(II) ions with EDTA. The potentiometric selectivity coefficient values indicate that the membrane sensor is highly selective for Cd(II) ions over a number of cations. Small amounts of surfactants do not disturb the functioning of the sensor. This electrode has also been used to estimate cadmium ions in real samples.