GHKL, an emergent ATPase/kinase superfamily

An interesting recent development is the recognition of a novel ATP-binding superfamily that includes diverse protein families such as DNA topoisomerase II, molecular chaperones Hsp90, DNA-mismatch-repair enzymes MutL and histidine kinases. The most singular unifying feature of this superfamily is the unconventional Bergerat ATP-binding fold. The far-reaching significance of this commonality is still in the process of being explored.

NMR structure of the histidine kinase domain of the E. coli osmosensor EnvZ

Bacteria live in capricious environments, in which they must continuously sense external conditions in order to adjust their shape, motility and physiology. The histidine-aspartate phosphorelay signal-transduction system (also known as the two-component system) is important in cellular adaptation to environmental changes in both prokaryotes and lower eukaryotes. In this system, protein histidine kinases function as sensors and signal transducers. The Escherichia coli osmosensor, EnvZ, is a transmembrane protein with histidine kinase activity in its cytoplasmic region. The cytoplasmic region contains two functional domains: domain A (residues 223-289) contains the conserved histidine residue (H243), a site of autophosphorylation as well as transphosphorylation to the conserved D55 residue of response regulator OmpR, whereas domain B (residues 290-450) encloses several highly conserved regions (G1, G2, F and N boxes) and is able to phosphorylate H243. Here we present the solution structure of domain B, the catalytic core of EnvZ. This core has a novel protein kinase structure, distinct from the serine/threonine/tyrosine kinase fold, with unanticipated similarities to both heatshock protein 90 and DNA gyrase B.

Solution structure of the homodimeric core domain of Escherichia coli histidine kinase EnvZ

Escherichia coli osmosensor EnvZ is a protein histidine kinase that plays a central role in osmoregulation, a cellular adaptation process involving the His-Asp phosphorelay signal transduction system. Dimerization of the transmembrane protein is essential for its autophosphorylation and phosphorelay signal transduction functions. Here we present the NMR-derived structure of the homodimeric core domain (residues 223-289) of EnvZ that includes His 243, the site of autophosphorylation and phosphate transfer reactions. The structure comprises a four-helix bundle formed by two identical helix-turn-helix subunits, revealing the molecular assembly of two active sites within the dimeric kinase.

Histidine kinases: diversity of domain organization

Histidine kinases play a major role in signal transduction in prokaryotes for the cellular adaptation to environmental conditions and stresses. Recent progress in the three-dimensional structure determination of two representative members of histidine kinases, EnvZ (class I) and CheA (class II), has revealed common structural features, as well as a kinase catalytic motif topologically similar to those of the ATP-binding domains of a few ATPases. They have also disclosed that there are significant differences in domain organization between class I and II histidine kinases, possibly reflecting their distinct locations, functions and regulatory mechanisms. In spite of this diversity, both class I and II histidine kinases use similar four-helix bundle motifs to relay phosphoryl groups from ATP to regulatory domains of response regulators. The previously known so-called transmitter domain of histidine kinase is further dissected into two domains: a CA (Catalytic ATP-binding) domain and a DHp (Dimerization Histidine phosphotransfer) domain for class I, or a CA domain and an HPt (Histidine-containing Phosphotransfer) domain for class II histidine kinases. From a comparative analysis of the CA domains of EnvZ, CheA and their ATPase homologues, the core elements of the CA domain have been derived. The apparent resemblance between DHp and HPt domains is only superficial, and significant differences between them are discussed.

Protein tyrosine phosphatases and neural development

During neural development, cells interact dynamically with each other and with the extracellular matrix, using cell signaling to control differentiation, axonogenesis, and survival. Enzymes that regulate protein tyrosine phosphorylation often lie at the core of such cell signaling. Protein tyrosine phosphatases (PTPases) are recognized as being of central importance here, and a growing family of PTPases are now known to be expressed in embryonic neurons and glia. Both receptor-like and cytoplasmic enzymes have been identified. The receptor family includes immunoglobulin superfamily members that influence cell-cell adhesion, proteoglycans that control neurite growth, and enzymes in Drosophila that regulate axon guidance and target cell recognition. Cytoplasmic PTPases are implicated in nerve cell commitment and potentially in the regulation of cell survival. This review outlines what we currently know about PTPases in the nervous system and presents concepts concerning their possible modes of action.

The critical role of the conserved Thr247 residue in the functioning of the osmosensor EnvZ, a histidine Kinase/Phosphatase, in Escherichia coli

The histidine kinase/phosphatase EnvZ helps Escherichia coli adapt to osmotic shock by controlling the phosphorylation state of the transcription factor OmpR, which regulates the levels of the outer membrane porin proteins OmpF and OmpC. We examined the effects of mutating the highly conserved Thr(247) residue in EnvZ. Using purified C-terminal domains of wild-type and mutant EnvZ proteins, we demonstrate that Thr(247) plays a vital role in EnvZ function, variously affecting its autokinase and phosphotransferase activities, but mostly its function as a phosphatase. The cytoplasmic domain of EnvZ (EnvZc) is composed of three segments: the linker domain (residues 180-222), domain A (residues 223-289), and domain B (residues 290-450). It has been shown that the isolated domain A itself can dephosphorylate phosphorylated OmpR. Here we show that mutating Thr(247) to Arg in domain A abolishes its phosphatase activity. Furthermore, using an in vivo beta-galactosidase activity assay of Taz1-1 (hybrid of the aspartate receptor Tar and EnvZ) constructs of the Thr(247) mutants in RU1012 cells expressing ompC-lacZ, we demonstrate that the external signal primarily down-regulates the phosphatase activity of EnvZ. Of the nine EnvZc(T247X) mutants (X = Ser, Ala, Cys, Lys, Asn, Glu, Gln, Tyr, or Arg) analyzed, only Ser functionally substituted for Thr at this position, whereas all the others displayed constitutive expression of beta-galactosidase.

Reverse phosphotransfer from OmpR to EnvZ in a kinase-/phosphatase+ mutant of EnvZ (EnvZ.N347D), a bifunctional signal transducer of Escherichia coli

EnvZ of Escherichia coli is a transmembrane histidine kinase belonging to the family of two-component signal transducing systems prevalent in prokaryotes and recently discovered in eukaryotes. In response to changes in medium osmolarity EnvZ regulates the level of phosphorylated OmpR, its conjugate response-regulating transcription factor for ompF and ompC genes. EnvZ has dual opposing enzymatic activities; OmpR-phosphorylase (kinase) and phospho-OmpR-dephosphorylase (phosphatase). The osmotic signal is proposed to regulate the ratio of the kinase to the phosphatase activities of EnvZ to modulate the level of OmpR phosphorylation. In this work we used a COOH-terminal fragment of a previously identified kinase-/phosphatase+ EnvZ mutant (EnvZ-N347D) to demonstrate that the phosphoryl group on phospho-OmpR is transferred back to EnvZ to the same histidine residue (His243) that is utilized for the autokinase reaction by the wild type protein. Phospho-EnvZ-N347D thus formed could also transfer its phosphoryl group back to OmpR. The phosphotransfer reaction from phospho-OmpR to EnvZ.N347D was inhibited by ADP while Mg2+ ions stimulated the dephosphorylation reaction, resulting in release of inorganic phosphate. These results indicate that the energy levels of phosphoryl groups on OmpR and EnvZ are very similar and that the phosphatase reaction in the EnvZ.N347D mutant involves a reversal of the phosphotransfer reaction from EnvZ to OmpR using the identical His243 residue.

Contributions of specific causes of death to lost life expectancy in severe mental illness

The life expectancy gap between people with severe mental illness (SMI) and the general population persists and may even be widening. This study aimed to estimate contributions of specific causes of death to the gap. Age of death and primary cause of death were used to estimate life expectancy at birth for people with SMI from a large mental healthcare case register during 2007-2012. Using data for England and Wales in 2010, death rates in the SMI cohort for each primary cause of death category were replaced with gender- and age-specific norms for that cause. Life expectancy in SMI was then re-calculated and, thus, the contribution of that specific cause of death estimated. Natural causes accounted for 79.2% of lost life-years in women with SMI and 78.6% in men. Deaths from circulatory disorders accounted for more life-years lost in women than men (22.0% versus 17.4%, respectively), as did deaths from cancer (8.1% versus 0%), but the contribution from respiratory disorders was lower in women than men (13.7% versus 16.5%). For women, cancer contributed more in those with non-affective than affective disorders, while suicide, respiratory and digestive disorders contributed more in those with affective disorders. In men, respiratory disorders contributed more in non-affective disorders. Other contributions were similar between gender and affective/non-affective groups. Loss of life expectancy in people with SMI is accounted for by a broad range of causes of death, varying by gender and diagnosis. Interventions focused on multiple rather than individual causes of death should be prioritised accordingly.

Mortality in first-contact psychosis patients in the U.K.: a cohort study

BACKGROUND

The excess mortality following first-contact psychosis is well recognized. However, the causes of death in a complete incidence cohort and mortality patterns over time compared with the general population are unknown.

METHOD

All 2723 patients who presented for the first time with psychosis in three defined catchment areas of the U.K. in London (1965-2004, n=2056), Nottingham (1997-1999, n=203) and Dumfries and Galloway (1979-1998, n=464) were traced after a mean of 11.5 years follow-up and death certificates were obtained. Data analysis was by indirect standardization.

RESULTS

The overall standardized mortality ratio (SMR) for first-contact psychosis was 184 [95% confidence interval (CI) 167-202]. Most deaths (84.2%, 374/444) were from natural causes, although suicide had the highest SMR (1165, 95% CI 873-1524). Diseases of the respiratory system and infectious diseases had the highest SMR of the natural causes of death (232, 95% CI 183-291). The risk of death from diseases of the circulatory system was also elevated compared with the general population (SMR 139, 95% CI 117-164) whereas there was no such difference for neoplasms (SMR 111, 95% CI 86-141). There was strong evidence that the mortality gap compared with the general population for all causes of death (p<0.001) and all natural causes (p=0.01) increased over the four decades of the study. There was weak evidence that cardiovascular deaths may be increasing relative to the general population (p=0.07).

CONCLUSIONS

People with first-contact psychosis have an overall mortality risk that is nearly double that of the general population. Most excess deaths are from natural causes. The widening of the mortality gap over the last four decades should be of concern to all clinicians involved in delivering healthcare.

A comparison of symptoms and family history in schizophrenia with and without prior cannabis use: implications for the concept of cannabis psychosis

BACKGROUND

There is considerable interest in cannabis use in psychosis. It has been suggested that the chronic psychosis associated with cannabis use, is symptomatically distinct from idiopathic schizophrenia. Several studies have reported differences in psychopathology and family history in people with schizophrenia according to whether or not they were cannabis users. We set out to test the hypotheses arising from these studies that cannabis use is associated with more bizarre behaviour, more thought disorder, fewer negative symptoms including blunted affect, more delusions of reference, more paranoid delusions and a stronger family history of schizophrenia.

METHOD

We used a case register that contained 757 cases of first onset schizophrenia, 182 (24%) of whom had used cannabis in the year prior to first presentation, 552 (73%) had not and 3% had missing data. We completed the OPCRIT checklist on all patients and investigated differences in the proportion of people with distractibility, bizarre behaviour, positive formal thought disorder, delusions of reference, well organised delusions, any first rank symptom, persecutory delusions, abusive/accusatory hallucinations, blunted affect, negative thought disorder, any negative symptoms (catatonia, blunted affect, negative thought disorder, or deterioration), lack of insight, suicidal ideation and a positive family history of schizophrenia, using chi square tests. Logistic regression modelling was then used to determine whether prior cannabis use affected the presence of the characteristics after controlling for age, sex and ethnicity.

RESULTS

There was no statistically significant effect of cannabis use on the presence of any of the above. There remained however a non-significant trend towards more insight (OR 0.65 p=0.055 for "loss of insight") and a finding of fewer abusive or accusatory hallucinations (OR 0.65 p=0.049) of borderline significance amongst the cannabis users. These were in the hypothesised direction. There was no evidence of fewer negative symptoms or greater family history amongst cannabis users.

CONCLUSION

We found few appreciable differences in symptomatology between schizophrenic patients who were or were not cannabis users. There were no differences in the proportion of people with a positive family history of schizophrenia between cannabis users and non-users. This argues against a distinct schizophrenia-like psychosis caused by cannabis.

A monomeric histidine kinase derived from EnvZ, an Escherichia coli osmosensor

Histidine kinases function as dimers. The kinase domain of the osmosensing histidine kinase EnvZ of Escherichia coli consists of two domains: domain A (67 residues) responsible for histidine phosphotransfer and dimerization, and domain B (161 residues) responsible for the catalytic and ATP-binding function. The individual structures of these two domains have been recently solved by NMR spectroscopy. Here, we demonstrate that an enzymatically functional monomeric histidine kinase can be constructed by fusing in tandem two domains A and one domain B to produce a single polypeptide (A-A-B). We show that this protein, EnvZc[AAB], is soluble and exists as a stable monomer. The autophosphorylation and OmpR kinase activities of the monomeric EnvZc[AAB] are similar to that of the wild-type EnvZ, while OmpR-binding and phosphatase functions are reduced. V8 protease digestion and mutational analyses indicate that His-243 of only the amino proximal domain A is phosphorylated. Based on these results, molecular models are proposed for the structures of EnvZc[AAB] and the kinase domain of EnvZ. The present results demonstrate for the first time the construction of a functional, monomeric histidine kinase, further structural studies of which may provide important insights into the structure-function relationships of histidine kinases.

Ovarian fibroma--clinical and histopathological characteristics

Twenty-three cases of ovarian fibroma, comprising 3% of all benign tumors seen over a 20-year period, were analyzed. It was unilateral in all cases affecting more commonly the left ovary (70%). Whilst a majority of cases (77%) were encountered in the reproductive age group, the tumor was rare before the second decade. Only in 13% of cases was ascitis clinically detectable. This was not influenced by the size and weight (average of 9.3 x 10.8 x 11.1 cm and 959 g, respectively) of the tumors; a smooth-surfaced tumor was, however, associated with a greater amount of peritoneal fluid. Varying degrees of calcification in some tumors are detectable on ultrasonography and occasionally on abdominal radiography. The classical Meig's Syndrome was seldom encountered. The histopathological features, diagnostic problems and management are discussed.

Relationship between rigidity-flexibility and cognitive abilities in adulthood

The interrelationship of measures of rigidity-flexibility and of psychometric intelligence is examined. The latent factors of Attitudinal Flexibility, Motor-Cognitive Flexibility, and Psychomotor Speed are derived from the Test of Behavioral Rigidity, and factors of Inductive Reasoning, Spatial Orientation, Verbal Ability, Numeric Ability, Verbal Memory, and Perceptual Speed are derived from the Thurstone Primary Mental Abilities Test and the Educational Testing Service Kit of Factor-Referenced Tests. The data base in this study comes from the fifth wave of the Seattle Longitudinal Study (N = 1,628; age range, 22-95 years). The Rigidity-Flexibility factors were found to be independent of the cognitive domain. Also, longitudinal stability of the factor structure of the rigidity-flexibility domain was confirmed for 837 participants tested in both 1977 and 1984.

Clinical evaluation of the electronic nose in the diagnosis of ear, nose and throat infection: a preliminary study

The term electronic nose describes an electronic system that is able to mimic the human sense of smell. Electronic noses have been developed over the last 10 or more years to perform a variety of identification tasks in various industries. More recently electronic noses have attracted new interest in their application in the field of medical diagnosis. The aim of this study is to explore the use of an electronic nose to identify and classify pathogens associated with ear, nose and throat (ENT) infections. In this study 90 bacterial swab samples were collected from 90 patients with ENT infections. Some of these samples were analysed immediately with a commercial electronic nose (Cyranose C320). Similar numbers of swabs were also taken from the same site of infection and were sent for microbiology culture and sensitivity. The electronic nose diagnosis was compared with the microbiology diagnosis and it was found that the electronic nose diagnosis was correct in 88.2 per cent of the cases, which is an encouraging result.

Protective or pathogenic immune response to genital chlamydial infection in women--a possible role of cytokine secretion profile of cervical mucosal cells

Little is known about genital mucosal immune response to chlamydial infection in women with or without sequelae (Chlamydia positive women with or without fertility disorders as infertility and multiple spontaneous abortions). Cervical lymphocytes were stimulated with chlamydial EBs and cytokine secretion was determined by ELISA, RT-PCR and ELISPOT assays. Stimulated cervical cells from women with fertility disorders (FD) secrete significantly (P<0.05) higher levels of IL-1beta, IL-6, IL-8 and IL-10 and cells from fertile women secrete significantly higher levels of IL-12 and IFN-gamma compared to other groups. RT-PCR analysis showed similar results for IFN-gamma and IL-12. For IL-10 and IL-4, mRNA expression levels were significantly higher (P<0.05) in cells obtained from women with FD compared to other groups. Results for ELISPOT assay were similar as those of RT-PCR. The results suggest that cytokine secretion profile of cervical cells may decide whether infection does not hamper fertility or will develop fertility disorder.

Cigarette smoke promotes HIV infection of primary bronchial epithelium and additively suppresses CFTR function

Recurrent lung infections are a common cause of morbidity and mortality in people living with HIV and this is exacerbated in smokers even when administered combination antiretroviral therapy (cART). The incidence of pneumonia is increased with smoking and treatment interruption and is directly dependent on viral load in patients when adjusted for CD4 counts. CFTR dysfunction plays an important role in aberrant airway innate immunity as it is pivotal in regulating mucociliary clearance (MCC) rates and other antibacterial mechanisms of the airway. In our earlier work, we have demonstrated that bronchial epithelium expresses canonical HIV receptors CD4, CCR5 and CXCR4 and can be infected with HIV. HIV Tat suppresses CFTR mRNA and function via TGF-β signaling. In the present study, we demonstrate that cigarette smoke (CS) potentiates HIV infection of bronchial epithelial cells by upregulating CD4 and CCR5 expression. HIV and CS individually and additively suppress CFTR biogenesis and function, possibly explaining the increased incidence of lung infections in HIV patients and its exacerbation in HIV smokers.

Using routine clinical and administrative data to produce a dataset of attendances at Emergency Departments following self-harm

Background

Self-harm is a significant public health concern in the UK. This is reflected in the recent addition to the English Public Health Outcomes Framework of rates of attendance at Emergency Departments (EDs) following self-harm. However there is currently no source of data to measure this outcome. Routinely available data for inpatient admissions following self-harm miss the majority of cases presenting to services.

We aimed to investigate (i) if a dataset of ED presentations could be produced using a combination of routinely collected clinical and administrative data and (ii) to validate this dataset against another one produced using methods similar to those used in previous studies.

Methods

Using the Clinical Record Interactive Search system, the electronic health records (EHRs) used in four EDs were linked to Hospital Episode Statistics to create a dataset of attendances following self-harm. This dataset was compared with an audit dataset of ED attendances created by manual searching of ED records. The proportion of total cases detected by each dataset was compared.

Results

There were 1932 attendances detected by the EHR dataset and 1906 by the audit. The EHR and audit datasets detected 77 % and 76 % of all attendances respectively and both detected 82 % of individual patients. There were no differences in terms of age, sex, ethnicity or marital status between those detected and those missed using the EHR method. Both datasets revealed more than double the number of self-harm incidents than could be identified from inpatient admission records.

Conclusions

It was possible to use routinely collected EHR data to create a dataset of attendances at EDs following self-harm. The dataset detected the same proportion of attendances and individuals as the audit dataset, proved more comprehensive than the use of inpatient admission records, and did not show a systematic bias in those cases it missed.

Nux vomica 30 prepared with and without succession shows antialcoholic effect on toads and distinctive molecular association

Adult toads, Bufo melanostictus, were administered Nux vomica (Nux v) 30 prepared with and without succussion on the tongue. The drug was mixed with sterile distilled water at the rate 0.05ml/ml water and given orally 0.05ml/individual. The control consisted of blank ethanol solution. Seeds of Strychnos nuxvomica were ground and extracted with 90% ethanol in the laboratory. Nux v 30 was prepared by successive dilution and succussion in 30 steps, Nux v 30 u was prepared by successive dilution only. Four hours after treatment, toads were given 25% ethanol i.p. at 8g/kg body weight. The duration of ethanol induced sleep time was recorded for each toad. Both Nux v 30 and Nux v 30 u significantly reduced ethanol induced sleep time in toads as compared to their respective controls. Electronic, infra red and nuclear magnetic resonance spectra of Nux v 30, Nux v 30 u and their diluent medium (90% ethanol) show marked differences from each other. These dilutions and ethanol 30 and ethanol 30 u show marked differences from each other with respect to spin-lattice relaxation time (T1) and chemical shift. The difference has been attributed to the variation in intra and inter-molecular association of ethanol and water.

Physicochemical and disintegrant properties of glutinous rice starch of Mizoram, India

The objective of the current work is to characterize the physicochemical and disintegrant properties of a starch obtained from a novel glutinous rice variety from Mizoram, India. Different properties such as total starch, apparent amylose content, protein and moisture content, along with micromeritic properties were evaluated. Viscosity was determined by Brookfield viscometer, DSC and FTIR spectroscopic analyses were also performed. The disintegrant efficiency was evaluated after dicalcium phosphate tablets were prepared using the starch as binder-disintegrant at different concentrations. The total starch content was found to be 83.48% with 2.83% crude protein and 10.22% moisture content. The average particle size of the starch was also found to be 11.39μm. DSC and FTIR analysis shows the starch possesses typical characteristics of starches. Results from disintegration efficiency study also showed that the starch possesses significant disintegration property and the disintegration efficiency increases with increase in concentration of the starch.

Unemployment, ethnicity and psychosis

OBJECTIVE

This study describes the incidence of psychosis in unemployed people and determines whether unemployment has a greater impact on the development of psychosis amongst Black minority groups than White groups.

METHOD

Patients with a first diagnosis of Research Diagnostic Criteria psychosis, in a defined area of London from 1998 to 2004, were identified. Crude and standardised incidence rates of psychosis amongst unemployed people for each ethnic group were calculated. Poisson regression modelling tested for interactions between unemployment and ethnicity.

RESULTS

Hundred cases occurred amongst employed people and 78 cases occurred amongst the unemployed people. When standardised to the employed White population of the area, White unemployed people had a standardised incidence ratio (SIR) of 11.7 (95% CI 6.4-19.7), Black Caribbean people had a SIR of 60.1(95% CI 39.3-88) and Black African people had a SIR of 40.7 (95% CI 25.8-61.1). There was no interaction however between ethnicity and unemployment (Likelihood ratio test P = 0.54).

CONCLUSION

Rates of psychosis are high amongst unemployed people in south London and extremely high amongst Black Caribbean and Black African unemployed people. There was no evidence however that the minority groups were particularly sensitive to the stresses, limitations or meaning of unemployment.

Effect of VMH lesion on sucrose-fed analgesia in formalin pain

The ingestion of sucrose (ad libitum) produces an immediate analgesic response to phasic noxious stimuli. The underlying mechanism for the analgesic effect of sucrose is attributed to its palatability, which mediates analgesia probably by the release of beta-endorphin in the hypothalamus. The present study was designed to explore the role of ventromedial hypothalamus in the mediation of sucrose-fed analgesia. Adult male albino rats each received (20%) sucrose solution orally through a separate bottle until they had ingested 4-5 ml. Their behavioral responses to tonic noxious stimulus in a formalin test were studied in pre- and postsucrose-fed rats of control and in the VMH lesion groups. The average pain rating of a 60-min session significantly (p < 0.01) decreased after sucrose feeding in control rats, from 1.94 +/- 0.13 to 1.45 +/- 0.14, but sucrose feeding by the VMH lesion rats did not alter their tonic nociceptive response from a 1.70 +/- 0.07 presucrose-fed state to a 1.71 +/- 0.08 postsucrose-fed state. VMH lesion per se did not alter the nociceptive response in comparison with controls. The results suggest that sucrose feeding produces analgesia to tonic noxious stimulus, which is abolished by lesion of the VMH, thereby indicating a significant role of VMH in sucrose-fed analgesia.

Relationship between rigidity-flexibility and cognitive abilities in adulthood

The interrelationship of measures of rigidity-flexibility and of psychometric intelligence is examined. The latent factors of Attitudinal Flexibility, Motor-Cognitive Flexibility, and Psychomotor Speed are derived from the Test of Behavioral Rigidity, and factors of Inductive Reasoning, Spatial Orientation, Verbal Ability, Numeric Ability, Verbal Memory, and Perceptual Speed are derived from the Thurstone Primary Mental Abilities Test and the Educational Testing Service Kit of Factor-Referenced Tests. The data base in this study comes from the fifth wave of the Seattle Longitudinal Study (N = 1,628; age range, 22-95 years). The Rigidity-Flexibility factors were found to be independent of the cognitive domain. Also, longitudinal stability of the factor structure of the rigidity-flexibility domain was confirmed for 837 participants tested in both 1977 and 1984.