Filamentous nestin and nonmuscle myosin IIB are associated with a migratory phenotype in neonatal rat cardiomyocytes.

Cardiomyocyte migration represents a requisite event of cardiogenesis and the regenerative response of the injured adult zebrafish and neonatal rodent heart. The present study tested the hypothesis that the appearance of the intermediate filament protein nestin in neonatal rat ventricular cardiomyocytes (NNVMs) was associated in part with the acquisition of a migratory phenotype. The cotreatment of NNVMs with phorbol 12,13-dibutyrate (PDBu) and the p38α/ß mitogen-activated protein kinase inhibitor SB203580 led to the de novo synthesis of nestin. The intermediate filament protein was subsequently reorganized into a filamentous pattern and redistributed to the leading edge of elongated membrane protrusions translating to significant lengthening of NNVMs. PDBu/SB203580 treatment concomitantly promoted the reorganization of nonmuscle myosin IIB (NMIIB) located predominantly at the periphery of the plasma membrane of NNVMs to a filamentous phenotype extending to the leading edge of elongated membrane protrusions. Coimmunoprecipitation assay revealed a physical interaction between NMIIB and nestin after PDBu/SB203580 treatment of NNVMs. In wild-type and heterozygous NMIIB embryonic hearts at E11.5-E14.5 days, nestin immunoreactivity was identified in a subpopulation of cardiomyocytes elongating perpendicular to the compact myocardium, at the leading edge of nascent trabeculae and during thickening of the compact myocardium. In mutant embryonic hearts lacking NMIIB protein expression, trabeculae formation was reduced, the compact myocardium significantly thinner and nestin immunoreactivity undetectable in cardiomyocytes at E14.5 days. These data suggest that NMIIB and nestin may act in a coordinated fashion to facilitate the acquisition of a migratory phenotype in neonatal and embryonic cardiomyocytes.

The World Federation of Neurology and the challenges in Environment Neurology.

Since its establishment the World Federation of Neurology (WFN) has manifested a keen interest in the environment and its relation to neurological diseases. Thus, in 2007 the WFN renamed the "Neurotoxicological Research Group" to "Environmental Neurology Research Group". In this short article, we review some recent events which illustrate the WFN involvement in Environmental Neurology as well its concerns about global health matters involving environmental issues.

Pax9 is required for cardiovascular development and interacts with Tbx1 in the pharyngeal endoderm to control 4th pharyngeal arch artery morphogenesis.

Developmental defects affecting the heart and aortic arch arteries are a significant phenotype observed in individuals with 22q11 deletion syndrome and are caused by a microdeletion on chromosome 22q11. TBX1, one of the deleted genes, is expressed throughout the pharyngeal arches and is considered a key gene, when mutated, for the arch artery defects. Pax9 is expressed in the pharyngeal endoderm and is downregulated in Tbx1 mutant mice. We show here that Pax9-deficient mice are born with complex cardiovascular malformations that affect the outflow tract and aortic arch arteries with failure of the 3rd and 4th pharyngeal arch arteries to form correctly. Transcriptome analysis indicated that Pax9 and Tbx1 may function together, and mice double heterozygous for Tbx1/Pax9 presented with a significantly increased incidence of interrupted aortic arch when compared with Tbx1 heterozygous mice. Using a novel Pax9Cre allele, we demonstrated that the site of this Tbx1-Pax9 genetic interaction is the pharyngeal endoderm, therefore revealing that a Tbx1-Pax9-controlled signalling mechanism emanating from the pharyngeal endoderm is required for crucial tissue interactions during normal morphogenesis of the pharyngeal arch artery system.

Neurological complications in patients with Plasmodium vivax malaria from Karachi, Pakistan.

BACKGROUND: Malaria remains an endemic disease in Pakistan with an estimated healthcare burden of 1.6 million cases annually, with Plasmodium vivax accounting for 67% of reported cases. P. vivax is the most common species causing malaria outside of Africa, with approximately 13.8 million reported cases worldwide. METHOD: We report a series of P. vivax cases with cerebral involvement that presented at Aga Khan University Hospital, Karachi, Pakistan. RESULTS: The majority of the patients presented with high-grade fever accompanied by projectile vomiting and abnormal behaviour, seizures, shock and unconsciousness. Seven of 801 patients with P. vivax monoinfection presented or developed cerebral complications. P. vivax infections were diagnosed based on peripheral smears and rapid diagnostic testing. CONCLUSION: P. vivax infection can lead to severe complications, although not with the frequency of Plasmodium falciparum infection. Current cases highlight an increasing trend of cerebral complications caused by P. vivax.

Imaging Cleared Embryonic and Postnatal Hearts at Single-cell Resolution.

Single clonal tracing and analysis at the whole-heart level can determine cardiac progenitor cell behavior and differentiation during cardiac development, and allow for the study of the cellular and molecular basis of normal and abnormal cardiac morphogenesis. Recent emerging technologies of retrospective single clonal analyses make the study of cardiac morphogenesis at single cell resolution feasible. However, tissue opacity and light scattering of the heart as imaging depth is increased hinder whole-heart imaging at single cell resolution. To overcome these obstacles, a whole-embryo clearing system that can render the heart highly transparent for both illumination and detection must be developed. Fortunately, in the last several years, many methodologies for whole-organism clearing systems such as CLARITY, Scale, SeeDB, ClearT, 3DISCO, CUBIC, DBE, BABB and PACT have been reported. This lab is interested in the cellular and molecular mechanisms of cardiac morphogenesis. Recently, we established single cell lineage tracing via the ROSA26-CreERT2; ROSA26-Confetti system to sparsely label cells during cardiac development. We adapted several whole embryo-clearing methodologies including Scale and CUBIC (clear, unobstructed brain imaging cocktails and computational analysis) to clear the embryo in combination with whole mount staining to image single clones inside the heart. The heart was successfully imaged at single cell resolution. We found that Scale can clear the embryonic heart, but cannot effectively clear the postnatal heart, while CUBIC can clear the postnatal heart, but damages the embryonic heart by dissolving the tissue. The methods described here will permit the study of gene function at a single clone resolution during cardiac morphogenesis, which, in turn, can reveal the cellular and molecular basis of congenital heart defects.

Variants at IRX4 as prostate cancer expression quantitative trait loci.

Genome-wide association studies (GWAS) have identified numerous prostate cancer-associated risk loci. Some variants at these loci may be regulatory and influence expression of nearby genes. Such loci are known as cis-expression quantitative trait loci (cis-eQTL). As cis-eQTLs are highly tissue-specific, we asked if GWAS-identified prostate cancer risk loci are cis-eQTLs in human prostate tumor tissues. We investigated 50 prostate cancer samples for their genotype at 59 prostate cancer risk-associated single-nucleotide polymorphisms (SNPs) and performed cis-eQTL analysis of transcripts from paired primary tumors within two megabase windows. We tested 586 transcript-genotype associations, of which 27 were significant (false discovery rate ≤10%). An equivalent eQTL analysis of the same prostate cancer risk loci in lymphoblastoid cell lines did not result in any significant associations. The top-ranked cis-eQTL involved the IRX4 (Iroquois homeobox protein 4) transcript and rs12653946, tagged by rs10866528 in our study (P=4.91 × 10(-5)). Replication studies, linkage disequilibrium, and imputation analyses highlight population specificity at this locus. We independently validated IRX4 as a potential prostate cancer risk gene through cis-eQTL analysis of prostate cancer risk variants. Cis-eQTL analysis in relevant tissues, even with a small sample size, can be a powerful method to expedite functional follow-up of GWAS.

Exome sequencing identifies recurrent SPOP, FOXA1 and MED12 mutations in prostate cancer.

Prostate cancer is the second most common cancer in men worldwide and causes over 250,000 deaths each year. Overtreatment of indolent disease also results in significant morbidity. Common genetic alterations in prostate cancer include losses of NKX3.1 (8p21) and PTEN (10q23), gains of AR (the androgen receptor gene) and fusion of ETS family transcription factor genes with androgen-responsive promoters. Recurrent somatic base-pair substitutions are believed to be less contributory in prostate tumorigenesis but have not been systematically analyzed in large cohorts. Here, we sequenced the exomes of 112 prostate tumor and normal tissue pairs. New recurrent mutations were identified in multiple genes, including MED12 and FOXA1. SPOP was the most frequently mutated gene, with mutations involving the SPOP substrate-binding cleft in 6-15% of tumors across multiple independent cohorts. Prostate cancers with mutant SPOP lacked ETS family gene rearrangements and showed a distinct pattern of genomic alterations. Thus, SPOP mutations may define a new molecular subtype of prostate cancer.

A computational framework discovers new copy number variants with functional importance.

Structural variants which cause changes in copy numbers constitute an important component of genomic variability. They account for 0.7% of genomic differences in two individual genomes, of which copy number variants (CNVs) are the largest component. A recent population-based CNV study revealed the need of better characterization of CNVs, especially the small ones (<500 bp).We propose a three step computational framework (Identification of germline Changes in Copy Number or IgC2N) to discover and genotype germline CNVs. First, we detect candidate CNV loci by combining information across multiple samples without imposing restrictions to the number of coverage markers or to the variant size. Secondly, we fine tune the detection of rare variants and infer the putative copy number classes for each locus. Last, for each variant we combine the relative distance between consecutive copy number classes with genetic information in a novel attempt to estimate the reference model bias. This computational approach is applied to genome-wide data from 1250 HapMap individuals. Novel variants were discovered and characterized in terms of size, minor allele frequency, type of polymorphism (gains, losses or both), and mechanism of formation. Using data generated for a subset of individuals by a 42 million marker platform, we validated the majority of the variants with the highest validation rate (66.7%) was for variants of size larger than 1 kb. Finally, we queried transcriptomic data from 129 individuals determined by RNA-sequencing as further validation and to assess the functional role of the new variants. We investigated the possible enrichment for variant's regulatory effect and found that smaller variants (<1 Kb) are more likely to regulate gene transcript than larger variants (p-value = 2.04e-08). Our results support the validity of the computational framework to detect novel variants relevant to disease susceptibility studies and provide evidence of the importance of genetic variants in regulatory network studies.

Incidental MRI lesions suggestive of multiple sclerosis in asymptomatic patients in Karachi, Pakistan.

The objective of this study was to identify asymptomatic patients with brain MRI lesions suggestive of multiple sclerosis (MS) in a low-prevalence area of Pakistan. Brain MRIs for 864 patients were reviewed at the Aga Khan University (Karachi, Pakistan) during an 8-month period of 2006 and 2007 to identify patients with lesions suggestive of MS. The lesions were characterised based on modified Barkhof criteria. Six (two females) (0.7%) of 864 patients fulfilled brain MRI criteria suggestive of MS. The mean number of MRI lesions (total lesions on T2) were 9 (range 5-14). Although Pakistan is considered a low-prevalence area for MS, 0.7% of brain MRI scans in patients without clinical MS symptoms showed lesions fulfilling brain MRI criteria of MS.

Multiple sclerosis in Pakistan.

We describe retrospective data from the largest series of patients (n=142) with multiple sclerosis (MS) from Pakistan. Mean age at onset was 27 years, with a female to male ratio of 1.45:1. The disease onset was polysymptomatic in 75% patients. Motor weakness was the most common onset symptom (70%), followed by sensory symptoms (45%). Optico-spinal type of MS was seen in only 3% of patients The course was relapsing-remitting (RR) in 81%, primary progressive (PP) in 21%, and secondary progressive (SP) in 4% of patients. Almost three-fourths of the patients were moderately (45%) or severely (31%) disabled at the time of evaluation. Two-thirds of patients with severe disability had a mean disease duration of only 5.2 years. In conclusion, MS is not uncommon in Pakistan, and many patients were found to have severe disability despite short disease duration.

MS in Asian countries.

This paper reviews all available English language literature on MS from Asian countries published between 1970 and 2005. Although limited data are available, the review reveals that western Asia--including the Middle East--has the highest prevalence of MS across the continent, and that MS in Asia largely resembles conventional MS in western countries. Opticospinal MS (a distinct clinical entity from conventional MS) is more common in eastern Asian regions. Larger epidemiological and genetic studies, with more complete ascertainment in various Asian populations, are needed so that we can understand the diversity of Asian MS.

Stroke-associated pneumonia: microbiological data and outcome.

INTRODUCTION: Pneumonia is a common complication after acute stroke. It affects the outcome adversely. However, data regarding microbiology of stroke-associated pneumonia and its effect on outcome is scarce. METHODS: Stroke-associated pneumonia was identified through chart review of all ICD-9 identified adult stroke patients admitted to our hospital over a period of four years (1998-2001). The demographical, laboratory, radiological, microbiological data and outcome of patients with stroke-associated pneumonia were recorded and analysed. RESULTS: 443 patients with stroke were admitted over the four-year period and 102 (23 percent) had stroke-associated pneumonia. Their ages range from 28 to 100 (mean 64+/-14) years. 69 (68 percent) were men. Median length of stay was nine days compared to four days for all stroke patients. 68 (67 percent) patients manifested pneumonia within 48 hours and 34 (33 percent) after 48 hours of admission. Yield of tracheal aspirate cultures was 38 percent and that of chest radiographs was 25 percent. Pseudomonas aeruginosa and Staphylococcus aureus were the most common organisms (12 percent each) followed by Streptococcus pneumoniae and Klebsiella pneumoniae (4 percent each). Patients with infiltrates on chest radiographs were more likely to have positive tracheal aspirate cultures (p-value is 0.003). 35 patients (34 percent) expired during hospital stay. Positive chest radiographs and tracheal aspirates were independent predictors of prolonged hospital stay (p-value is less than 0.005). CONCLUSION: Pneumonia is a common medical complication of stroke. It is associated with a high mortality and prolongs the hospital stay. The yield of chest radiographs and tracheal aspirates is low. However, these are independent predictors of prolonged hospital stay. Pseudomonas aeruginosa and Staphylococcus aureus are most common organisms in stroke-associated pneumonia.

Extra temporal involvement in herpes simplex encephalitis.

Temporal lobe abnormalities on brain imaging have been described as strong evidence for herpes simplex encephalitis (HSE) in appropriate clinical settings. Extra temporal abnormalities are less well described in these patients. We retrospectively reviewed 20 patients of HSE and found extra temporal involvement in 11 (55%) patients. Three patients (15 %) had pure extra temporal abnormalities. Twelve patients (60%) had temporal lobe involvement, four patients (20%) had pure temporal lobe involvement and five patients (25%) had normal CT/MRI scans. Our study suggests that extra temporal involvement on brain imaging is common in HSE and in a significant minority of the patients this can even be the sole abnormality.

Prognostic indicators in patients with intracranial tuberculoma: a review of 102 cases.

OBJECTIVE: To see the characteristics, course and outcome of patients suffering from intracranial tuberculoma. METHODS: Retrospective review of 102 patients diagnosed as intracranial tuberculoma at a tertiary care center over 10 years. RESULTS: A total of 102 cases were seen with an age range of 1 to 75 years (mean, 30 years). Predisposing factors included Diabetes mellitus (8 patients) and pregnancy or puerperium (7 patients). Five pediatric patients had tuberculoma despite documented BCG vaccination. Fever (59%), headache (57%), meningeal irritation (36%) were the commonest presenting features; one-third of patients were drowsy or comatosed at presentation. Cerebrospinal fluid analysis was performed in 63 patients, of whom 88% had elevated protein, 83% had low glucose, and 84% had pleocytosis (one-third with neutrophilia). Forty-nine (50%) patients had clinical or laboratory evidence of concomitant tuberculous meningitis. Chest radiographs showed active or old tuberculous infection (25%), with a miliary pattern in 20%. Two-thirds of subjects had multiple tuberculomas (mean, 4.5 lesions per patient) on contrast CT or MRI scan. Hydrocephalus was present in 37 (37%) patients of which 21 required shunt surgery. Thirty-nine patients had > 9 months of follow up; 17 patients showed complete recovery, 20 patients had partial recovery, and 2 patients had no response. Coma at presentation and miliary pattern on chest X-ray were predictors of poor prognosis. CONCLUSION: The study demonstrate that fever, headache, signs of meningeal irritation and cranial nerve palsies are common presenting features. Complete recovery was seen in 40% patients. Coma and military TB are predictors of poor prognosis.

Spectrum of complications and mortality of bacterial meningitis: an experience from a developing country.

OBJECTIVE: The aim of this study was to obtain data on predisposing factors, causative organisms and their associated mortality and complications related to acute bacterial meningitis. METHODS: The chart review of all patients in whom acute bacterial meningitis was diagnosed at The Aga Khan University Hospital from January 1995 through December 2001. RESULTS: One hundred ninety-four patients were included in study. There were 146 males and 48 females. The mean age of our study population was 41 +/- 12.3 years. One hundred and ninety (97.9%) patients had community-acquired meningitis; only 4 (2.0%) patients developed meningitis nosocomially. The two most common predisposing factors were diabetes mellitus (13.9%) and otitis media (7.7%) among all 194 patients. A significant proportion of patients with complications had diabetes mellitus (24.6%, p < 0.001). CSF and blood cultures were positive in 53 (27.3%) and 42 (21.6%) patients respectively; there was no statistical difference found. The most common organisms isolated were Streptococcus pneumoniae in 35 (36.8%) patients followed by Neisseria meningitides in 30 (31.5%) patients. Approximately 68% of positive cultures yielded S. pneumoniae and N. meningitides (p < 0.0001). The overall mortality rate was 22.1%. The mortality rate for Streptococcus pneumoniae was 17.1%. The highest mortality was observed in patients with Pseudomonal meningitis where all four patients expired followed by mortality rate of 85.7% in Escherichia coli afflicted patients (p < 0.001). Complications occurred in 73 (37.6%) patients with persistent complications in 31 (42.4%) patients. Complications resolved in 34 (46.5%) patients. The most common complications were seizures (12.8%) and cranial nerve palsies (11.3%). Seizures were more likely to occur in older patients (p < 0.05) whereas hydrocephalus was more common in younger patients (p < 0.05). CONCLUSION: Bacterial Meningitis remains a serious disease associated with substantial morbidity and mortality. Most cases are community acquired with S. Pneumoniae being the most common pathogen. Old age, diabetes mellitus, a positive culture, seizures as a complication and late stage in the disease are the important predictors of a poor outcome.