Characterization of Rv3868, an essential hypothetical protein of the ESX-1 secretion system in Mycobacterium tuberculosis

Rv3868, a conserved hypothetical protein of the ESAT-6 secretion system of Mycobacterium tuberculosis, is essential for the secretion of at least four virulence factors. Each protein chain is approximately 63 kDa and assembles into a hexamer. Limited proteolysis demonstrates that it consists of two domains joined by a linker. The N-terminal domain is a compact, helical domain of approximately 30 kDa and apparently functions to regulate the ATPase activity of the C-terminal domain and the oligomerization. The nucleotide binding site is situated in the C-terminal domain, which exhibits ATP-dependent self-association. It is also the oligomerization domain. Dynamic fluorescence quenching studies demonstrate that the domain is proximal to the C terminus in the apoprotein and exhibits a specific movement upon ATP binding. In silico modeling of the domains suggests that Arg-429 of a neighboring subunit forms a part of the binding site upon oligomerization. Mutational analysis of binding site residues demonstrates that the Arg-429 functions as the important "sensor arginine" in AAA-ATPases. Protein NMR experiments involving CFP-10 and activity assays rule out a general chaperone-like function for Rv3868. On the other hand, ATP-dependent "open-close" movements of the individual domains apparently enable it to interact and transfer energy to co-proteins in the ESX-1 pathway.

Neuroimaging of toxic and metabolic disorders

Imaging of the brain, magnetic resonance imaging (MRI) in particular, is a key adjunctive tool in the diagnosis and management of toxic-metabolic disorders such as alcoholism, mitochondrial encephalopathies, disorders of iron or copper metabolism, exposure to carbon monoxide, radiotherapy, immunosuppressive agents, toluene, and recreational drugs. In this article, we review the neuroimaging findings of common toxic and metabolic disorders focusing on the role of conventional MRI. We also consider advanced imaging methods, such as magnetic resonance spectroscopy, diffusion MRI, and positron emission tomography. We hope this article will prove useful to trainees and practitioners in the clinical and imaging fields of the neurosciences.

Solid-pseudopapillary tumour of the pancreas: a report of a rare case

The solid pseudopapillary tumour (SPT) of the pancreas is an uncommon cystic pancreatic neoplasm mostly seen in young females. We present a large SPT in a 16-year-old female who presented with acute onset upper- and mid-quadrant abdominal pain associated with nausea and vomiting for 4 days. The lesion was demonstrated by abdominal ultrasound and by computed tomography, which was successfully removed surgically.

Modulation of AMPA receptor GluR1 subunit phosphorylation in neurons by the intravenous anaesthetic propofol

BACKGROUND

The ionotropic glutamate receptor is a potential molecular site in the central nervous system that general anaesthetics may interact with to produce some of their biological actions. Protein phosphorylation has been well documented to occur in the intracellular C-terminal domain of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) subtype of glutamate receptors, which represents a pivotal mechanism for the post-translational modulation of AMPA receptor functions. In this study, we investigated a possible influence of an i.v. anaesthetic agent propofol on the phosphorylation of AMPA receptor GluR1 subunits in cultured neurons.

METHODS

The effect of propofol on phosphorylation of GluR1 subunits at serine 831 and 845 was assayed in cultured rat striatal and cortical neurons by western blot with phospho- and site-specific antibodies.

RESULTS

Propofol consistently elevated phosphorylation of GluR1 subunits at the C-terminal serine 845 site in both striatal and cortical neurons. The elevation in phosphorylation was concentration-dependent and started at a low concentration (3 microM). This increase in serine 845 phosphorylation was rapid and sustained during the entire course of propofol exposure. In contrast to serine 845, phosphorylation of GluR1 at serine 831 was not altered by propofol in striatal and cortical neurons. Total GluR1 abundance remained unchanged in response to propofol incubation.

CONCLUSIONS

These data indicate that propofol possesses the ability to upregulate AMPA receptor GluR1 subunit phosphorylation at a specific serine 845 site in neurons and provide evidence supporting the AMPA receptor as a molecular target for general anaesthetics.

A novel connexin50 mutation associated with congenital nuclear pulverulent cataracts

PURPOSE

To screen for mutations of connexin50 (Cx50)/GJA8 in a panel of patients with inherited cataract and to determine the cellular and functional consequences of the identified mutation.

METHODS

All patients in the study underwent a full clinical examination and leucocyte DNA was extracted from venous blood. The GJA8 gene was sequenced directly. Connexin function and cellular trafficking were examined by expression in Xenopus oocytes and HeLa cells.

RESULTS

Screening of the GJA8 gene identified a 139 G to A transition that resulted in the replacement of aspartic acid by asparagine (D47N) in the coding region of Cx50. This change co-segregated with cataract among affected members of a family with autosomal dominant nuclear pulverulent cataracts. While pairs of Xenopus oocytes injected with wild type Cx50 RNA formed functional gap junction channels, pairs of oocytes injected with Cx50D47N showed no detectable intercellular conductance. Co-expression of Cx50D47N did not inhibit gap junctional conductance of wild type Cx50. In transiently transfected HeLa cells, wild type Cx50 localised to appositional membranes and within the perinuclear region, but Cx50D47N showed no immunostaining at appositional membranes with immunoreactivity confined to the cytoplasm. Incubation of HeLa cells transfected with Cx50D47N at 27 degrees C resulted in formation of gap junctional plaques.

CONCLUSIONS

The pulverulent cataracts present in members of this family are associated with a novel GJA8 mutation, Cx50D47N, that acts as a loss-of-function mutation. The consequent decrease in lens intercellular communication and changes associated with intracellular retention of the mutant connexin may contribute to cataract formation.

MRI in multiple sclerosis: what's inside the toolbox?

Magnetic resonance imaging (MRI) has played a central role in the diagnosis and management of multiple sclerosis (MS). In addition, MRI metrics have become key supportive outcome measures to explore drug efficacy in clinical trials. Conventional MRI measures have contributed to the understanding of MS pathophysiology at the macroscopic level yet have failed to provide a complete picture of underlying MS pathology. They also show relatively weak relationships to clinical status such as predictive strength for clinical progression. Advanced quantitative MRI measures such as magnetization transfer, spectroscopy, diffusion imaging, and relaxometry techniques are somewhat more specific and sensitive for underlying pathology. These measures are particularly useful in revealing diffuse damage in cerebral white and gray matter and therefore may help resolve the dissociation between clinical and conventional MRI findings. In this article, we provide an overview of the array of tools available with brain and spinal cord MRI technology as it is applied to MS. We review the most recent data regarding the role of conventional and advanced MRI techniques in the assessment of MS. We focus on the most relevant pathologic and clinical correlation studies relevant to these measures.

Endocarditis due to Chryseobacterium meningosepticum

Chryseobacterium meningosepticum is a gram negative rod widely distributed in nature. It is known to cause meningitis in neonates and premature infants. Adult infections are not common and are usually nosocomially acquired. We report an unusual case of native valve endocarditis in a 58-year-old man due to this organism. A high degree of suspicion and correct identification and sensitivity testing is required to diagnose infections by this rare isolate.

Analysis of complex formation and immune response of CFP-10 and ESAT-6 mutants

ESAT-6 and CFP-10 form a 1:1 heterodimeric complex which contributes to the virulence of Mycobacterium tuberculosis H37Rv. Based on the structure of CFP-10-ESAT-6 complex, we have selected four point mutations each of CFP-10 and ESAT-6 and have analyzed complex formation for the 25 possible combinations between wild-type and mutant CFP-10 and ESAT-6 proteins. We observed that the mutations L25R or F58R of CFP-10 and L29D or L65D of ESAT-6 lead to disruption of complex formation. We have evaluated the immunogenic responses of the wild-type and mutant CFP-10 and ESAT-6 proteins, the wild-type CFP-10-ESAT-6 complex, six complex-forming and two non-complex-forming combinations of wild-type/mutant CFP-10 and ESAT-6 proteins. CFP-10 mutants I21R, L25R, and W43R were found to have better immunogenic potential than wt-CFP-10, while none of the ESAT-6 mutants were better than wt-ESAT-6. Very interestingly, we have discovered that the non-complex-forming mixture of CFP-10-I21R and ESAT-6-L29D gives a strong immunogenic response.

Health outcome measurements in children with sleep disordered breathing

OBJECTIVE

To validate the Child Health Questionnaire, measure quality of life in children with obstructive sleep apnoea and assess the impact of surgery.

METHODS

The primary carer of a consecutive series of 42 patients with sleep disordered breathing referred to a paediatric otolaryngology clinic completed the Child Health Questionnaire (version PF 28). Questionnaires were analysed for data quality and completeness, item/scale correlation, internal consistency and discriminant validity, interscale correlation and reliability. Following overnight pulse oximetry 37 children were diagnosed with obstructive sleep apnoea and underwent adenotonsillectomy.

RESULTS

Child Health Questionnaire Physical Functioning 28 demonstrated excellent measuring characteristics in our population. Compared with normative data, children with obstructive sleep apnoea and their carers suffer a significant quality of life deficit, involving 10 of 13 subscales of the Child Health Questionnaire. This was most prominent in parental emotional impact, general health perception and family activities. There was no correlation between the severity of obstructive sleep apnoea and quality of life indices. Following surgery, there was a significant improvement in all Child Health Questionnaire subscales, which became equivalent to healthy children.

CONCLUSION

The Child Health Questionnaire Physical Functioning 28 is an accurate and reliable way of assessing the impact of obstructive sleep apnoea on the quality of life in children in Britain. This appears to be significant in most aspects of a child's life, but is fully reversed following surgery.

Anti-stress constituents of Evolvulus alsinoides: an ayurvedic crude drug

Bioactivity-guided purification of n-BuOH soluble fraction from the ethanol extract of Evolvulus alsinoides resulted in the isolation of two new compounds, 2,3,4-trihydroxy-3-methylbutyl 3-[3-hydroxy-4-(2,3,4-trihydroxy-2-methylbutoxy)-phenyl]-2-propenoate (1) and 1,3-di-O-caffeoyl quinic acid methyl ester (2) along with six known compounds, caffeic acid (3), 6-methoxy-7-O-beta-glucopyranoside coumarin (4), 2-C-methyl erythritol (5), kaempferol-7-O-beta-glucopyranoside (6), kaempferol-3-O-beta-glucopyranoside (7) and quecetine-3-O-beta-glucopyranoside (8). The structure of new compounds 1 and 2 were elucidated by spectroscopic analysis, while known compounds were confirmed by direct comparison of their NMR data with those reported in literature. This is the first report of the presence of phenolic constituents in Evolvulus alsinoides. The isolated compounds 1-5 and 8 were screened for anti-stress activity in acute stress induced biochemical changes in adult male Sprague-Dawley rats. Stress exposure has resulted in significant increase of plasma glucose, adrenal gland weight, plasma creatine kinase (CK), and corticosterone levels. Compound 1 displayed most promising antistress effect by normalizing hyperglycemia, plasma corticosterone, CK and adrenal hypertrophy, while compounds 2 and 3 were also effective in normalizing most of these stress parameters, however compounds 4, 5 and 8 were ineffective in normalizing these parameters.

Iron in chronic brain disorders: imaging and neurotherapeutic implications

Iron is important for brain oxygen transport, electron transfer, neurotransmitter synthesis, and myelin production. Though iron deposition has been observed in the brain with normal aging, increased iron has also been shown in many chronic neurological disorders including Alzheimer's disease, Parkinson's disease, and multiple sclerosis. In vitro studies have demonstrated that excessive iron can lead to free radical production, which can promote neurotoxicity. However, the link between observed iron deposition and pathological processes underlying various diseases of the brain is not well understood. It is not known whether excessive in vivo iron directly contributes to tissue damage or is solely an epiphenomenon. In this article, we focus on the imaging of brain iron and the underlying physiology and metabolism relating to iron deposition. We conclude with a discussion of the potential implications of iron-related toxicity to neurotherapeutic development.

The oncogenic potential of human papillomaviruses: a review on the role of host genetics and environmental cofactors

Human papillomaviruses (HPVs), with over 100 genotypes, are a very complex group of human pathogenic viruses. In most cases, HPV infection results in benign epithelial proliferations (verrucae). However, oncogenic types of HPV may induce malignant transformation in the presence of cofactors. For example, over 99% of all cervical cancers and a majority of vulval, vaginal, anal and penile cancers are the result of oncogenic HPV types. Such HPV types have been increasingly linked to other epithelial cancers involving the skin, larynx and oesophagus. Although viral infection is necessary for neoplastic transformation, evidence suggests that host and environmental cofactors are also required. Research investigating HPV oncogenesis is complex and quite extensive. The inability to produce mature HPV virions in animal models has been a major limitation in fully elucidating the oncogenic potential and role of associated cofactors in promoting malignant transformation in HPV-infected cells. We have reviewed the literature and provide a brief account of the current understanding of HPV oncogenesis, emphasizing the role of genetic susceptibility, immune response, and environmental and infectious cofactors.

Ligand based virtual screening and biological evaluation of inhibitors of chorismate mutase (Rv1885c) from Mycobacterium tuberculosis H37Rv

We have identified new lead candidates that possess inhibitory activity against Mycobacterium tuberculosis H37Rv chorismate mutase by a ligand-based virtual screening optimized for lead evaluation in combination with in vitro enzymatic assay. The initial virtual screening using a ligand-based pharmacophore model identified 95 compounds from an in-house small molecule database of 15,452 compounds. The obtained hits were further evaluated by molecular docking and 15 compounds were short listed based on docking scores and the other scoring functions and subjected to biological assay. Chorismate mutase activity assays identified four compounds as inhibitors of M. tuberculosis chorismate mutase (MtCM) with low K(i) values. The structural models for these ligands in the chorismate mutase binding site will facilitate medicinal chemistry efforts for lead optimization against this protein.

Validation of the Mayo Dysphagia Questionnaire

While multiple instruments characterize upper gastrointestinal symptoms, a validated instrument devoted to the measurement of a spectrum of esophageal dysphagia attributes is not available. Therefore, we constructed and validated the Mayo Dysphagia Questionnaire (MDQ). The 27 items of the MDQ underwent content validity, feasibility, concurrent validity, reproducibility, internal consistency, and construct validity testing. To assess content validity, five esophageal subspecialty gastroenterologists reviewed the items to ensure inclusion of pertinent domains. Feasibility testing was done with eight outpatients who refined problematic items. To assess concurrent validity, 70 patient responses on the MDQ were compared to responses gathered in a structured patient-physician interview. A separate group of 70 outpatients completed the MDQ twice to assess the reproducibility of each item. A total of 148 patients participated in the validation process (78 [53%] men; mean age 62). On average, the MDQ took 6 minutes to complete. A single item (odynophagia) tested poorly with a kappa value of <0.4. Otherwise, the majority of concurrent validity kappa values were in the good to excellent range with a mean of 0.63 (95% CI 0.22-0.89). The majority of reproducibility kappa values were also in the good to excellent range with a median kappa value of 0.76 (interquartile range: 0.67-0.81). Cronbach's alpha values were excellent in the range of 0.86-0.88. Spearman rank correlation coefficients to assess construct validity were also excellent in the range of 0.87-0.98. Thus, the MDQ is a concise instrument that demonstrates overall excellent concurrent validity, reproducibility, internal consistency, and construct validity for the features of esophageal dysphagia.

Dendritic cells pulsed with either secretory antigens of Mycobacterium tuberculosis or live mycobacteria show a differential expansion of Th1, Th2 and Th3 type T cells in immune mice (92.10)

Dendritic cells (DCs) can prime naïve or immune T cells and expand Th1, Th2 and Th3 type of T cells that determine protection against pathogens. While the Th1 immunity has been thought to be protective against tuberculosis, the ability of vaccines to induce Th1-Th3 immunity is unclear. Emerging tuberculosis vaccines include DNA vaccines encoding 85 complex (A, B, C), ESAT-6 and CFP-10 (ES antigens) or live attenuated Mycobacterium tuberculosis (MTB) in comparison with BCG vaccine. Interestingly, MTB H37Rv secretes all three ES antigens while BCG secretes Ag85 but lacks ESAT-6 and CFP-10. We therefore hypothesized that ES antigens and live bacteria may induce different types of T cell responses and the efficacy of vaccines delivering these would vary in mice.

METHODS: Bone marrow derived C57Bl/6 DCs were infected with live H37Rv or BCG or were pulsed with Ag85(ABC), ESAT-6 or CFP-10 antigens. After 24 h, they were cocultured with naïve T cells or immune T cells from heat killed MTB immunized mice. T cells were then stained for intracellular T-bet/IFN-&#947;, GATA3/IL-4 and Foxp3/IL-10 to determine the expansion of Th1, Th2 and Th3 response respectively.

RESULTS: ES antigens induced a strong Th1 response with very little Th2 or Th3 responses in immune T cells. Paradoxically, H37Rv and BCG induced a Th1 response as well as significant levels of Th2 and Th3 type of T cells.

CONCLUSIONS: We suggest that live mycobacterial vaccines concurrently induce deleterious Th2 and Th3 T cells during vaccination or infection that may affect the protective function of Th1 T cells.

T1- and T2-Based MRI Measures of Diffuse Gray Matter and White Matter Damage in Patients with Multiple Sclerosis

Magnetic resonance imaging (MRI) has emerged as a powerful noninvasive tool to assist in the diagnosis and monitoring of multiple sclerosis (MS). In addition, investigators have used MRI metrics as supportive outcome measures to explore drug efficacy in clinical trials. Conventional MRI surrogates provide information at the macroscopic level but lack sensitivity and specificity in identifying the full extent of underlying MS pathology. They also show relatively weak relationships to clinical status such as predictive strength for clinical change. Advanced MRI techniques involving quantitative measures of diffuse damage in normal appearing (NA) white matter (WM) and gray matter (GM) may help in resolving this apparent clinical MRI paradox. T2 hypointensity has been described in the GM of patients with MS and has been linked to physical disability, cognitive dysfunction, and brain atrophy. While this T2 hypointensity is thought to represent iron deposition, this awaits pathologic confirmation. Advanced MRI measures of iron deposition such as R2, R2*, R2' relaxometry, 3T imaging and other new approaches are beginning to be applied to studies of MS and should yield interesting information. Both T1 and T2 relaxometry have a role in detecting damage in NA brain tissue that escapes detection by conventional MRI lesion measures. For example, T2 mapping may allow an assessment of myelin content in NAWM. In this review, we will focus on MRI advances in the last 10 years pertaining to T1 and T2 measures of diffuse GM and WM damage.