Prospects for a Vaccine for Clostridium difficile

Clostridium difficile diarrhoea and colitis is a new disease that is attributable to broad spectrum antibiotic therapy. During the past 2 decades C. difficile has become one of the most common nosocomial pathogens in the developed world. As changing demographics create an increasingly elderly population and the use of broad spectrum antimicrobials continues to expand, C. difficile is likely to become increasingly problematic. Disease caused by this organism is caused by the inflammatory actions of its 2 toxins, A and B, on the intestinal mucosa. Human antibody responses to these toxins are common in the general population and in patients with C. difficile-associated disease. There is substantial, albeit inconclusive, evidence to indicate that antitoxin antibodies provide protection against severe, prolonged or recurrent C. difficile diarrhoea. Immunity induced by oral or parenteral passive administration of antibody is protective in animal models of C. difficile infection. In humans, intravenous passive immunisation with pooled human immunoglobulin has been successful in the treatment of recurrent and severe C. difficile colitis. Human trials of oral passive immunotherapy with bovine immunoglobulin therapy are in progress. Formalin-inactivated culture filtrate from toxigenic C. difficile, as well as purified and inactivated toxins, have been used to successfully immunise animals. Similar preparations are under investigation as possible human vaccines. Antibiotic therapy is effective in treating most individual patients with C. difficile diarrhoea, but has proven ineffective in reducing the overall incidence of nosocomial infection. Active immunisation is probably the most promising approach to long term control of this difficult iatrogenic disease.     

Teratogenicity of anticonvulsant drugs. IV: The association of clefting and epilepsy

Cleft lip with or without cleft palate (CL/P) is the most common congenital malformation reported among infants of epileptic mothers. This study sought to examine the relative roles of anticonvulsant teratogenicity and other factors responsible for this association. Among 175 families with a proband with isolated CL/P, there were 13 parents with epilepsy and a high frequency of other family members with CL/P and epilepsy. Evaluation of the 13 cases suggested that teratogenicity of anticonvulsant drugs was not the primary factor responsible for the observed association of maternal epilepsy and clefting. Among 140 families with a proband with clefting other than CL/P, there were no instances of parental epilepsy observed.     

Clinical comparison of the Roche Septi-Chek and Dupont Isolator blood culture systems

A study was conducted to compare the recovery of clinical isolates by the DuPont Isolator and Roche Septi-Chek blood culture systems. A total of 5,262 blood culture specimens were processed by the two systems. Of these, 358 cultures contained significant isolates: 219 were positive in both systems, 68 were recovered only by Isolator, 71 were recovered by Septi-Chek only (not statistically significant). Of the isolates recovered in both systems, 159 were positive the same day, 55 were recovered first by Isolator, and 5 were recovered first by Septi-Chek. In cases where Isolator recovered organisms first, the average difference in time was one to two days. Regarding particular groups of organisms, there was no difference between the systems in recovery of Enterobacteriaceae, anaerobes, yeast, and gram-positive bacteria, except for Streptococcus pneumoniae. Septi-Chek recovered S. pneumoniae significantly more often. These results suggest that these two systems are essentially comparable, except with S. pneumoniae, although the Isolator frequently provided results more rapidly.     

Laforin preferentially binds the neurotoxic starch-like polyglucosans, which form in its absence in progressive myoclonus epilepsy

Lafora disease (LD) is a fatal and the most common form of adolescent-onset progressive epilepsy. Fulminant endoplasmic reticulum (ER)-associated depositions of starch-like long-stranded, poorly branched glycogen molecules [known as polyglucosans, which accumulate to form Lafora bodies (LBs)] are seen in neuronal perikarya and dendrites, liver, skeletal muscle and heart. The disease is caused by loss of function of the laforin dual-specificity phosphatase or the malin E3 ubiquitin ligase. Towards understanding the pathogenesis of polyglucosans in LD, we generated a transgenic mouse overexpressing inactivated laforin to trap normal laforin's unknown substrate. The trap was successful and LBs formed in liver, muscle, neuronal perikarya and dendrites. Using immunogold electron microscopy, we show that laforin is found in close proximity to the ER surrounding the polyglucosan accumulations. In neurons, it compartmentalizes to perikaryon and dendrites and not to axons. Importantly, it binds polyglucosans, establishing for the first time a direct association between the disease-defining storage product and disease protein. It preferentially binds polyglucosans over glycogen in vivo and starch over glycogen in vitro, suggesting that laforin's role begins after the appearance of polyglucosans and that the laforin pathway is involved in monitoring for and then preventing the formation of polyglucosans. In addition, we show that the laforin interacting protein, EPM2AIP1, also localizes on the polyglucosan masses, and we confirm laforin's intense binding to LBs in human LD biopsy material.     

The search for a marsupial XIC reveals a break with vertebrate synteny

X-chromosome inactivation (XCI) evolved in mammals to deal with X-chromosome dosage imbalance between the XX female and the XY male. In eutherian mammals, random XCI of the soma requires a master regulatory locus known as the ‘X-inactivation center’ (XIC/Xic), wherein lies the noncoding XIST/Xist silencer RNA and its regulatory antisense Tsix gene. By contrast, marsupial XCI is imprinted to occur on the paternal X chromosome. To determine whether marsupials and eutherians share the XIC-driven mechanism, we search for the sequence equivalents in the genome of the South American opossum, Monodelphis domestica. Positional cloning and bioinformatic analysis reveal several interesting findings. First, protein-coding genes that flank the eutherian XIC are well-conserved in M. domestica, as well as in chicken, frog, and pufferfish. However, in M. domestica we fail to identify any recognizable XIST or TSIX equivalents. Moreover, cytogenetic mapping shows a surprising break in synteny with eutherian mammals and other vertebrates. Therefore, during the evolution of the marsupial X chromosome, one or more rearrangements broke up an otherwise evolutionarily conserved block of vertebrate genes. The failure to find XIST/TSIX in M. domestica may suggest that the ancestral XIC is too divergent to allow for detection by current methods. Alternatively, the XIC may have arisen relatively late in mammalian evolution, possibly in eutherians with the emergence of random XCI. The latter argues that marsupial XCI does not require XIST and opens the search for alternative mechanisms of dosage compensation.     

Traumatic Memories: Empirical Foundations, Forensic and Clinical Implications

This article reviews empirical research on memories for negative personal experiences among adults. It examines basic concepts (including neural underpinnings), theoretical models of the affect-memory relationship, and data from three sources: victims or witnesses to crimes and atrocities, "flashbulb memories" for traumatic events, and laboratory simulations of shocking experiences. Evidence suggests that memories for traumatic experiences contain more central than peripheral detail, are reasonably accurate and well-retained for very long periods, but are not completely indelible. Assertions of eyewitness memory's vulnerability to change through suggestion have overstated the evidence. Forensic and clinical implications are discussed and a plea issued for more study of the memory phenomena that characterize posttraumatic stress disorder (PTSD) and are the focus of trauma survivors' treatment.     

Rapid identification by the Micro-ID system of Enterobacteriaceae detected by urine screening.

Previous studies have demonstrated that organisms detected by urine screening can be processed for rapid identification and antimicrobial susceptibility testing directly from urine or urine screening broth. In the present study, an improved method for processing such specimens was evaluated. Organisms were harvested by centrifugation from positive urine screening broth, and inocula were prepared for rapid identification by the Micro-ID system and rapid susceptibility testing by the Autobac system. Nearly 2,500 urine specimens were analyzed by urine screening, and 206 specimens had significant growth of gram-negative, oxidase-negative bacilli. These organisms, prepared by the centrifugation procedure, were identified and tested for susceptibility to antimicrobial agents. For comparison, identifications by the Micro-ID system and antimicrobial susceptibility tests by the Autobac system were performed on the same organisms the next day with inocula prepared from colonies growing from standard urine cultures. The results demonstrated that 95% of the organisms were correctly identified by this procedure, and susceptibility testing by the rapid method gave results in 94% agreement with the standard method. These results demonstrate that organisms detected by urine screening can be accurately identified and tested for antimicrobial susceptibility after centrifugation from urine screening broth. This system provides a practical procedure or same-day reporting of urine culture results.     

Rapid detection and identification of human adenovirus species by adenoplex, a multiplex PCR-enzyme hybridization assay

Human adenoviruses (AdV) have been implicated in a wide variety of diseases and are ubiquitous in populations worldwide. These agents are of concern particularly in immunocompromised patients, children, and military recruits, resulting in severe disease or death. Clinical diagnosis of AdV is usually achieved through routine viral cell culture, which can take weeks for results. Immunofluorescence and enzyme-linked immunosorbent assay-based techniques are more timely but lack sensitivity. The ability to distinguish between the six different AdV species (A to F) is diagnostically relevant, as infections with specific AdV species are often associated with unique clinical outcomes and epidemiological features. Therefore, we developed a multiplex PCR-enzyme hybridization assay, the Adenoplex, using primers to the fiber gene that can simultaneously detect all six AdV species A through F in a single test. The limit of detection (LOD) based on the viral 50% tissue culture infective dose/ml for AdV A, B, C, D, E, and F was 10(-2), 10(-1), 10(-1), 10(-2), 10(-1), and 10(-2), respectively. Similarly, the LOD for the six DNA controls ranged from 10(2) to 10(3) copies/ml. Twelve common respiratory pathogens were tested with the Adenoplex, and no cross-reactivity was observed. We also validated our assay using clinical specimens spiked with different concentrations of AdV strains of each species type and tested by multiplex PCR and culture. The results demonstrated an overall sensitivity and specificity of Adenoplex of 100%. This assay can be completed in as few as 5 h and provides a rapid, specific, and sensitive method to detect and subtype AdV species A through F.     

Gluthatione-S-transferase P1 polymorphism I105V in familial and sporadic prostate cancer

Several reports suggest that the glutathione-S-transferase (GST) family of enzymes is involved in a variety of cancers, due to their carcinogen-detoxification properties. A polymorphism in codon 105 of the pi variant (GSTP1 I105V), which affects the enzymatic activity of the enzyme, has been linked to the incidence of cancers from different organs. However, the published data in prostate cancer (PCa) is controversial. Some studies report an association with the GSTP1 I105V polymorphism and sporadic PCa, whereas other studies report no association. Recently, one study showed a positive correlation between the GSTP1 I105V polymorphism and familial PCa in a Japanese population. In the present study, we assessed the correlation of the GSTP1 I105V polymorphism with familial and sporadic PCa in an American population. We analyzed DNA samples from 438 patients with familial PCa, 499 patients with sporadic PCa, and 510 controls. We found no significant association between the GSTP1 I105V polymorphism and familial or sporadic PCa when compared to the control group [odds ratio (OR) =1.0 (0.74-1.37); P=0.58]. Moreover, no association was found after stratification for age of diagnosis, Gleason grade, or lymph node involvement [OR =0.84 (0.65-1.09), P=0.37]. These data indicate that there is no associated risk for sporadic or familial PCa in American families containing the GSTP1 I105V polymorphism.