Voxel-based morphometric MRI post-processing in MRI-negative focal cortical dysplasia followed by simultaneously recorded MEG and stereo-EEG

We aim to report on the usefulness of a voxel-based morphometric MRI post-processing technique in detecting subtle epileptogenic structural lesions. The MRI post-processing technique was implemented in a morphometric analysis program (MAP), in a 30-year-old male with pharmacoresistant focal epilepsy and negative MRI. MAP gray-white matter junction file facilitated the identification of a suspicious structural lesion in the right frontal opercular area. The electrophysiological data by simultaneously recorded stereo-EEG and MEG confirmed the epileptogenicity of the underlying subtle structural abnormality. The patient underwent a limited right frontal opercular resection, which completely included the area detected by MAP. Surgical pathology revealed focal cortical dysplasia (FCD) type IIb. Postoperatively the patient has been seizure-free for 2 years. This study demonstrates that MAP has promise in increasing the diagnostic yield of MRI reading in challenging patients with "non-lesional" MRIs. The clinical relevance and epileptogenicity of MAP abnormalities in patients with epilepsy have not been investigated systematically; therefore it is important to confirm their pertinence by performing electrophysiological recordings. When confirmed to be epileptogenic, such MAP abnormalities may reflect an underlying subtle cortical dysplasia whose complete resection can lead to seizure-free outcome.

Wavelet analysis for single molecule localization microscopy

Localization of single molecules in microscopy images is a key step in quantitative single particle data analysis. Among them, single molecule based super-resolution optical microscopy techniques require high localization accuracy as well as computation of large data sets in the order of 10(5) single molecule detections to reconstruct a single image. We hereby present an algorithm based on image wavelet segmentation and single particle centroid determination, and compare its performance with the commonly used gaussian fitting of the point spread function. We performed realistic simulations at different signal-to-noise ratios and particle densities and show that the calculation time using the wavelet approach can be more than one order of magnitude faster than that of gaussian fitting without a significant degradation of the localization accuracy, from 1 nm to 4 nm in our range of study. We propose a simulation-based estimate of the resolution of an experimental single molecule acquisition.

Assessment of trends of ofloxacin resistance in Mycobacterium tuberculosis

PURPOSE

Ofloxacin (OFX) is one of the potent fluoroquinolone (FQ) recommended to treat MDR-TB. Over a decade, the preexposure of this drug for the treatment of other bacterial infections has resulted in acquisition of FQ resistance among Mycobacterium tuberculosis strains. Considering this possibility, a study was undertaken in a tertiary care center in the capital city (India) to assess the drug resistance trends of OFX among susceptible and multidrug resistant (MDR) strains of M. tuberculosis.

MATERIALS AND METHODS

A total of 102 M. tuberculosis isolates (47 susceptible to first-line drugs and 55 MDR isolates) were screened for susceptibility testing of OFX with a critical concentration of 2 μg/ml by Lowenstein Jensen (LJ) proportion method.

RESULTS

The results showed 40 (85.1%) isolates among 47 susceptible isolates and 34 (61.8%) isolates among 55 MDR isolates, were found to be susceptible to OFX. Fisher's exact test showed significant P-value (0.0136) demonstrating 1.377 fold (95% confidence interval) increased risk to become resistant to OFX than susceptible isolates. These finding shows decreased OFX susceptibility is not only limited to MDR isolates but also increasingly seen in susceptible strains as a result of drug abuse.

CONCLUSIONS

Our finding were not alarming, but highlights the general risk of acquiring resistance to OFX, jeopardizing the potential for these drugs to be used as second-line anti-TB agents in the management of drug-resistant TB and creating incurable TB strains .

Evaluation of nucleic acid probe for rapid identification of Mycobacterium tuberculosis complex in extra-pulmonary culture isolates

Patients infected with Non-tuberculous mycobacteria (NTM) usually do not respond to conventional anti-tubercular treatment and are misdiagnosed as infection with multi-drug resistant strains of mycobacterium tuberculosis (M.tb) due to lack of correct species identification, particularly in the developing countries like India. One of the challenges faced by clinicians in the treatment of tuberculosis is the absence of an easy, reliable and rapid identification tool that can accurately differentiate disease caused by M.tb complex from NTM. Keeping this in consideration, the performance of species specific nucleic acid probe i.e. Accuprobe was assessed and compared with conventional niacin production, nitrate reductase assay techniques for identification of M.tb complex in 80 mycobacterial isolates obtained from different extra-pulmonary sites. Accuprobe identified 62 isolates (77.5%) as M. tuberculosis complex and remaining 18 isolates (22.5%) as NTM whereas 64 isolates (80%) were identified as M.tb and rest 16 (20%) were interpreted as NTM by conventional biochemical techniques. The overall agreement between both techniques was 96.9% The sensitivity, specificity, positive predictive value(PPV) and negative predictive value (NPV) shown by accuprobe were 96.9%, 100%, 96.9%, and 88.9% respectively. Thus, accuprobe has showed impressive sensitivity and specificity giving results in < 3 hrs from culture-positive isolates and have sure edge over conventional biochemical methods which are, nonetheless, labour intensive and cumbersome to perform thus delaying prompt mycobacterial identification.

Bihemispheric brain stimulation facilitates motor recovery in chronic stroke patients

OBJECTIVE

Motor recovery after stroke depends on the integrity of ipsilesional motor circuits and interactions between the ipsilesional and contralesional hemispheres. In this sham-controlled randomized trial, we investigated whether noninvasive modulation of regional excitability of bilateral motor cortices in combination with physical and occupational therapy improves motor outcome after stroke.

METHODS

Twenty chronic stroke patients were randomly assigned to receive 5 consecutive sessions of either 1) bihemispheric transcranial direct current stimulation (tDCS) (anodal tDCS to upregulate excitability of ipsilesional motor cortex and cathodal tDCS to downregulate excitability of contralesional motor cortex) with simultaneous physical/occupational therapy or 2) sham stimulation with simultaneous physical/occupational therapy. Changes in motor impairment (Upper Extremity Fugl-Meyer) and motor activity (Wolf Motor Function Test) assessments were outcome measures while functional imaging parameters were used to identify neural correlates of motor improvement.

RESULTS

The improvement of motor function was significantly greater in the real stimulation group (20.7% in Fugl-Meyer and 19.1% in Wolf Motor Function Test scores) when compared to the sham group (3.2% in Fugl-Meyer and 6.0% in Wolf Motor Function Test scores). The effects outlasted the stimulation by at least 1 week. In the real-stimulation group, stronger activation of intact ipsilesional motor regions during paced movements of the affected limb were found postintervention whereas no significant activation changes were seen in the control group.

CONCLUSIONS

The combination of bihemispheric tDCS and peripheral sensorimotor activities improved motor functions in chronic stroke patients that outlasted the intervention period. This novel approach may potentiate cerebral adaptive processes that facilitate motor recovery after stroke.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that for adult patients with ischemic stroke treated at least 5 months after their first and only stroke, bihemispheric tDCS and simultaneous physical/occupational therapy given over 5 consecutive sessions significantly improves motor function as measured by the Upper Extremity Fugl-Meyer assessment (raw change treated 6.1 ± 3.4, sham 1.2 ± 1.0).

Ictal bigeminy

Seizures can influence cardiac autonomic function and cause abnormalities in the electrocardiogram (EKG). A case of stereotypical bigeminy during left temporal lobe seizures recorded in the epilepsy monitoring unit is presented. The mechanism is likely due to spread of the ictal discharge to primary visceromotor regions in the left insula (Island of Reil). This case illustrates the potential influence of ictal brain activity on cardiac electrophysiology.

Mutation detection rate and spectrum in familial hypercholesterolaemia patients in the UK pilot cascade project

Cascade testing using DNA-mutation information is now recommended in the UK for patients with familial hypercholesterolaemia (FH). We compared the detection rate and mutation spectrum in FH patients with a clinical diagnosis of definite (DFH) and possible (PFH) FH. Six hundred and thirty-five probands from six UK centres were tested for 18 low-density lipoprotein receptor gene (LDLR) mutations, APOB p.Arg3527Gln and PCSK9 p.Asp374Tyr using a commercial amplification refractory mutation system (ARMS) kit. Samples with no mutation detected were screened in all exons by single strand conformation polymorphism analysis (SSCP)/denaturing high performance liquid chromatography electrophoresis (dHPLC)/direct-sequencing, followed by multiplex ligation-dependent probe amplification (MLPA) to detect deletions and duplications in LDLR.The detection rate was significantly higher in the 190 DFH patients compared to the 394 PFH patients (56.3% and 28.4%, p > 0.00001). Fifty-one patients had inadequate information to determine PFH/DFH status, and in this group the detection rate was similar to the PFH group (25.5%, p = 0.63 vs PFH). Overall, 232 patients had detected mutations (107 different; 6.9% not previously reported). The ARMS kit detected 100 (44%) and the MLPA kit 11 (4.7%). Twenty-eight (12%) of the patients had the APOB p.Arg3527Gln and four (1.7%) had the PCSK9 p.Asp374Tyr mutation. Of the 296 relatives tested from 100 families, a mutation was identified in 56.1%. In 31 patients of Indian/Asian origin 10 mutations (two previously unreported) were identified. The utility of the ARMS kit was confirmed, but sequencing is still required in a comprehensive diagnostic service for FH. Even in subjects with a low clinical suspicion of FH, and in those of Indian origin, mutation testing has an acceptable detection rate.

The use of E-test for the drug susceptibility testing of Mycobacterium tuberculosis - a solution or an illusion?

AIM

To evaluate E-test as a tool for rapid determination of drug susceptibility against the conventional LJ method focusing on reliability, expense, ease of standardization and performance of the technique in low resource settings.

MATERIALS AND METHODS

A total of 74 clinical isolates (2004-2005) of Mycobacterium tuberculosis were tested using E-test for susceptibility to streptomycin (STM), isoniazid (INH), rifampicin (RIF) and ethambutol (EMB) by E-strip and LJ (LJPM) proportion methods.

RESULTS

The LJPM method, the gold standard, detected resistance against STM in 16.2%, INH in 40.5%, RIF in 18.9% and EMB in 27% cases. In comparison, the resistance values showed by E-test was 66.67% for STM, 57.14% for INH 71.43% for RIF and 80% for EMB. The susceptible correlation was 90.32% for STM, 73.91% for INH, 93.33% for RIF and 59.26% for EMB. E-test correctly identified only eight of the 12 (66.6%) MDR isolates and wrongly identified four isolates which were not MDR. The overall agreement between the two methods was only 48.6%. Resistant isolates showed false positive resistance observed while using E-strip towards all the drugs.

CONCLUSION

E-strips are not quite feasible as a replacement for LJ-proportion method on a large scale due to high risk of cross contamination, laboratory infection, expense associated with it and high false positive resistance observed to all first line drugs. However, the good correlation observed for RIF between the two methods indicates that E-test could contribute to the role in rapid screening of MDR TB isolates as rifampicin mutations are invariably observed in MDR TB isolates.

Tenofovir-associated renal and bone toxicity

OBJECTIVES

The aims of the study were to describe the clinical presentation and renal and bone abnormalities in a case series of HIV-infected patients receiving treatment with tenofovir (TDF), and to recommend appropriate screening for toxicity related to TDF.

METHODS

Patients were identified from referrals to a specialist HIV renal clinic. Patients were included if treatment with TDF was assessed as the primary cause of the renal function impairment and clinical data were available prior to and following discontinuation of TDF treatment. Data were collected from case note review and clinic databases.

RESULTS

Twenty-two patients (1.6% of all those who received TDF) were identified with TDF-associated renal toxicity. All had normal serum creatinine prior to TDF therapy. All presented with proteinuria. On stopping TDF, renal function improved. Eight patients had confirmed Fanconi syndrome. Twelve patients presented with bone pain and osteomalacia was confirmed on an isotope bone scan in seven of these patients. The findings (in those patients tested) of tubular proteinuria, reduced tubular transport maximum of phosphate (TmP), and glycosuria were all consistent with the proximal tubule being the site of toxicity.

CONCLUSION

Renal toxicity remains a concern in patients treated with TDF. Clinical presentation may be with renal dysfunction, Fanconi syndrome or osteomalacia. Our investigations suggest proximal tubular toxicity as a common pathogenic mechanism.

Concomitant TB and cryptococcosis in HIV-infected patients

Four cases of concomitant tuberculosis and cryptococcosis infection in HIV-positive patients are described. As the HIV pandemic progresses and the proportion of patients with end-stage disease increases, a high suspicion of incidence and unusual forms of infections must always be kept in mind.

Isolation and characterization of naphthalene-degrading bacteria from sediments of Cadiz area (SW Spain)

Petroleum hydrocarbon contamination of harbor sediments from shipping activity, fuel oil spills, and runoffs are becoming a great concern because of the toxicity and recalcitrance of many of the fuel components. Polycyclic aromatic hydrocarbons (PAHs) are of most concern due to their toxicity, low volatility, resistance to degradation, and high affinity for sediments. Microorganisms, especially bacteria, play an important role in the biodegradation of these hydrocarbons. The objective of the present study was to characterize and isolate PAH-(naphthalene) degrading bacteria in the coastal sediments of Cadiz (SW Spain), since this area is mostly polluted by PAH occurrence. A total of 16 naphthalene-utilizing bacteria were isolated from these sites. Introduction of bacteria isolated from contaminated sediments into mineral medium contributed to the increased rate of hydrocarbon utilization. The bacterial isolates obtained from these sites are very potent in utilizing naphthalene and crude oil. It would be interesting to assess if the selected naphthalene-degrading isolates may degrade other compounds of similar structure. Hence these isolates could be very helpful in bioremediating the PAH-contaminated sites. Further pursue on this work might represent eco-friendly solution for oil contamination on sea surface and coastal area.

European AIDS Clinical Society (EACS) guidelines on the prevention and management of metabolic diseases in HIV

BACKGROUND

Metabolic diseases are frequently observed in HIV-infected persons and, as the risk of contracting these diseases is age-related, their prevalence will increase in the future as a consequence of the benefits of antiretroviral therapy (ART).

SUMMARY OF GUIDELINES

All HIV-infected persons should be screened at regular intervals for a history of metabolic disease, dyslipidaemia, diabetes mellitus, hypertension and alteration of body composition; cardiovascular risk and renal function should also be assessed. Efforts to prevent cardiovascular disease will vary in intensity depending on an individual's absolute risk of ischaemic heart disease and should be comprehensive in nature. Lifestyle interventions should focus on counselling to stop smoking, modify diet and take regular exercise. A healthy diet, exercise and maintaining normal body weight tend to reduce dyslipidaemia; if not effective, a change of ART should be considered, followed by use of lipid-lowering medication in high-risk patients. A pre-emptive switch from thymidine analogues is recommended to reduce the risk of development or progression of lipoatrophy. Intra-abdominal fat accumulation is best managed by exercise and diet. Prevention and management of type 2 diabetes mellitus and hypertension follow guidelines used in the general population. When using medical interventions to prevent and/or treat metabolic disease(s), impairment of the efficacy of ART should be avoided by considering the possibility of pharmacokinetic interactions and compromised adherence. Specialists in HIV and specialists in metabolic diseases should consult each other, in particular in difficult-to-treat cases.

CONCLUSION

Multiple and relatively simple approaches exist to prevent metabolic diseases in HIV-infected persons; priority should be given to patients at high risk of contracting these diseases.

Role of enteric fever in ileal perforations: an overstated problem in tropics?

PURPOSE

To determine the role of enteric fever in ileal perforations.

METHODS

A prospective cohort of 47 patients of ileal perforation was subjected to clinical examination and investigations for APACHE II scoring. Blood, ulcer edge biopsy, mesenteric lymph node and peritoneal aspirate were subjected to culture to determine the predominant aerobic bacterial isolate and its antibiogram.

RESULTS

Seven patients (14.9%) required intensive care and seven (14.9%) developed septicaemia. Mortality was 17%. Highest isolation rate was seen in ulcer edge (70.2%) followed by lymph node (66%) culture. The bacterial spectrum was Escherichia coli (23.4%), Enterococcus faecalis (21.3%), Salmonella enterica serovar Typhi (6.3%), Salmonella enterica serovar Paratyphi A (4.2%), etc.

CONCLUSIONS

Enteric fever organisms are not the predominant causative agents of ileal perforations. Culture of ulcer edge biopsy, lymph node is crucial for aetiological diagnosis. The use of APACHE II triaging and prescription of antimicrobials based on the local pattern of susceptibility profile of the aetiological agent is recommended.

Clinical and mycological profile of cryptococcosis in a tertiary care hospital

This study examined the extent of cryptococcosis in clinically diagnosed cases of meningitis in HIV-1 seropositive and apparently immunocompetent patients. One hundred and forty-six samples, obtained from 126 chronic meningitis patients comprised of cerebrospinal fluid (CSF), blood, sputum and urine. The samples were processed by standard microbiological procedures. Cryptococcal isolates were identified by microscopy, cultural characteristics, melanin production on niger seed agar and hydrolysis of urea. The isolates were further speciated on cannavanine glycine bromothymol blue (CGB) media. Cryptococcal antigen detection of CSF samples was performed by latex agglutination test (LAT). Minimum inhibitory concentration (MIC) of amphotericin B for the isolates was also tested. Cryptococcosis was diagnosed in 13 patients (eight HIV-1 seropositive and five apparently immunocompetent). Cryptococcus neoformans var. neoformans was the predominant isolate. Cryptococcal antigen was detected in all, whereas microscopy could detect yeast cells in nine patients. The isolates were sensitive to amphotericin B. CD4 cell counts ranged from 8 to 96/cu mm. The study concludes that all CSF samples with clinical diagnosis of subacute and chronic meningitis should be subjected to tests for detection of Cryptococcus in clinical laboratory irrespective of the immune status.