Clostridium difficile-associated diarrhea in a region of Quebec from 1991 to 2003: a changing pattern of disease severity

BACKGROUND

Recent reports suggest that Clostridium difficile colitis may be evolving into a more severe disease. During the second half of 2002 we noted an increase in the number of patients with severe C. difficile-associated diarrhea (CDAD) in our institution. We describe cases of CDAD at our institution over a 13-year period and investigate changes in illness severity.

METHODS

We undertook a retrospective chart review of all cases of CDAD diagnosed at the Centre hospitalier universitaire de Sherbrooke from Jan. 1, 1991, to Dec. 31, 2003. Because the hospital serves a well-defined population of Quebec, we were also able to calculate population-based incidence during this period. We abstracted data on individual patients from patient charts and from hospital and pharmacy computer databases. We defined cases of CDAD as having a positive C. difficile cytotoxicity assay result, or endoscopic or histopathological evidence of pseudomembranous colitis. A case was considered complicated if one or more of the following was observed: megacolon, perforation, colectomy, shock requiring vasopressor therapy, or death within 30 days after diagnosis.

RESULTS

A total of 1721 cases of CDAD were diagnosed during the study period. The incidence increased from 35.6 per 100,000 population in 1991 to 156.3 per 100,000 in 2003; among patients aged 65 years or more, it increased from 102.0 to 866.5 per 100,000. The proportion of cases that were complicated increased from 7.1% (12/169) in 1991-1992 to 18.2% (71/390) in 2003 (p < 0.001), and the proportion of patients who died within 30 days after diagnosis increased from 4.7% (8/169) in 1991-1992 to 13.8% (54/390) in 2003 (p < 0.001). A high leukocyte count (20.0 small ha, Cyrillic 10(9)/L or greater) and an elevated creatinine level (200 micromol/L or greater) were strongly associated with adverse outcomes: in 2003, 45 (40.9%) of 110 patients with a high leukocyte count or creatinine level, or both, had complicated CDAD and 28 (25.5%) died within 30 days after diagnosis. After adjustment for age and other confounding factors, patients initially given oral vancomycin therapy had a risk of progression to complicated CDAD that was 79% lower than the risk among patients initially treated with metronidazole (adjusted odds ratio 0.2, 95% confidence interval 0.06-0.8, p = 0.02).

INTERPRETATION

An epidemic of CDAD with an increased case-fatality rate has had important consequences on the elderly population of our region. Our observational data suggest that the equivalence of vancomycin and metronidazole in the treatment of CDAD needs to be questioned.

How does parkinsonism start? Prodromal parkinsonism motor changes in idiopathic REM sleep behaviour disorder

Parkinsonism, as a gradually progressive disorder, has a prodromal interval during which neurodegeneration has begun but cardinal manifestations have not fully developed. A systematic direct assessment of this interval has never been performed. Since patients with idiopathic REM sleep behaviour disorder are at very high risk of parkinsonism, they provide a unique opportunity to observe directly the development of parkinsonism. Patients with idiopathic REM sleep behaviour disorder in an ongoing cohort study were evaluated annually with several quantitative motor measures, including the Unified Parkinson's Disease Rating Scale, Purdue Pegboard, alternate-tap test and timed up-and-go. Patients who developed parkinsonism were identified from this cohort and matched according to age to normal controls. Their results on motor testing from the preceding years were plotted, and then assessed with regression analysis, to determine when markers first deviated from normal values. Sensitivity and specificity of quantitative motor markers for diagnosing prodromal parkinsonism were assessed. Of 78 patients, 20 developed parkinsonism. On regression analysis, the Unified Parkinson's Disease Rating Scale first intersected normal values at an estimated 4.5 years before diagnosis. Voice and face akinesia intersected earliest (estimated prodromal interval = 9.8 years), followed by rigidity (4.4 years), gait abnormalities (4.4 years) and limb bradykinesia (4.2 years). Quantitative motor tests intersected normal values at longer prodromal intervals than subjective examination (Purdue Pegboard = 8.6 years, alternate-tap = 8.2, timed up-and-go = 6.3). Using Purdue Pegboard and the alternate-tap test, parkinsonism could be detected with 71-82% sensitivity and specificity 3 years before diagnosis, whereas a Unified Parkinson's Disease Rating Scale score >4 identified prodromal parkinsonism with 88% sensitivity and 94% specificity 2 years before diagnosis. Removal of action tremor scores improved sensitivity to 94% and specificity to 97% at 2 years before diagnosis (cut-off >3). Although distinction between conditions was often difficult, prodromal dementia with Lewy bodies appeared to have a slower progression than Parkinson's disease (prodromal interval = 6.0 versus 3.8 years). Using a cut-off of Unified Parkinson's Disease Rating Scale >3 (excluding action tremor), 25% of patients with 'still-idiopathic' REM sleep behaviour disorder demonstrated evidence of possible prodromal parkinsonism. Therefore, using direct assessment of motor examination before parkinsonism in a REM sleep behaviour disorder, we have estimated a prodromal interval of ∼4.5 years on the Unified Parkinson's Disease Rating Scale; other quantitative markers may detect parkinsonism earlier. Simple quantitative motor measures may be capable of reliably detecting parkinsonism, even before a clinical diagnosis can be made by experienced movement disorders neurologists.

Long-term oxygen therapy can reverse the progression of pulmonary hypertension in patients with chronic obstructive pulmonary disease

Sixteen patients with severe chronic obstructive pulmonary disease (COPD) (average values at the onset of O2 therapy: FEV1, 891 +/- 284 ml; PaO2, 50.2 +/- 6.6 mmHg; PaCO2, 51.0 +/- 6.4 mmHg) underwent 3 consecutive right heart catheterizations. The first was performed 47 +/- 28 months (T0) before the onset of long-term O2 therapy (LTO2). The second was performed just before the onset of LTO2 (T1). The third was performed after 31 +/- 19 months of LTO2 (T2). Oxygen therapy (15 to 18 h/day) was prescribed on the basis of usual criteria. From T0 to T1, PaO2 decreased from 59.3 +/- 9.4 to 50.2 +/- 6.6 mmHg, and mean pulmonary arterial pressure (Ppa) worsened from 23.3 +/- 6.8 to 28.0 +/- 7.4 mmHg (p less than 0.005). From T1 to T2, PaO2 was stable, whereas Ppa decreased from 28.0 +/- 7.4 to 23.9 +/- 6.6 mmHg (p less than 0.05). Pulmonary hypertension improved in 12 of the 16 patients. Before the onset of LTO2 (from T0 to T1), there was a yearly increase in Ppa of 1.47 +/- 2.3 mmHg, whereas during LTO2 a yearly decrease of 2.15 +/- 4.4 mmHg was observed, and the difference between these 2 values was highly significant. The changes in Ppa either from T0 to T1 or from T1 to T2 were not associated with concomitant changes in cardiac output or pulmonary capillary wedge pressure but were related to changes in pulmonary vascular resistance. These results suggest that LTO2 for 15 to 18 h/day can reverse the progression of pulmonary hypertension in a high percentage of patients with severe COPD, but that normalization of Ppa is rarely observed.

Cryptogenic organizing pneumonia. Characteristics of relapses in a series of 48 patients. The Groupe d'Etudes et de Recherche sur les Maladles "Orphelines" Pulmonaires (GERM"O"P)

Cryptogenic organizing pneumonia (COP) is a clinicopathologic syndrome characterized by rapid resolution with corticosteroids, but frequent relapses when treatment is tapered or stopped. We retrospectively studied relapses in 48 cases of biopsy-proven COP. One or more relapses (mean 2.4 +/- 2.2) occurred in 58%. At first relapse, 68% of patients were still under treatment for the initial episode. Compared with the no-relapse group, nine patients with multiple (>/= 3) relapses had longer delays between first symptoms and treatment onset (22 +/- 17 versus 11 +/- 8 wk, p = 0.02), and elevated gamma-glutamyltransferase (124 +/- 98 versus 29 +/- 13 IU/L, p = 0.001) and alkaline phosphatase (190 +/- 124 versus 110 +/- 68 IU/L, p = 0.04) levels. Relapses did not adversely affect outcome. Corticosteroid treatment side effects occurred in 25% of patients. Standardized treatment in 14 patients allowed a reduction of prednisone cumulated doses (p < 0.05) without affecting outcome or relapse rate. We conclude that: (1) delayed treatment increases the risk of relapses; (2) mild cholestasis identifies a subgroup of patients with multiple relapses; (3) relapses do not affect outcome, and prolonged therapy to suppress relapses appears unnecessary; (4) a standardized treatment allows a reduction in steroid doses.

On the evolution of Tn21-like multiresistance transposons: sequence analysis of the gene (aacC1) for gentamicin acetyltransferase-3-I(AAC(3)-I), another member of the Tn21-based expression cassette

The aminoglycoside-3-O-acetyltransferase-I gene (aacC1) from R plasmids of two incompatibility groups (R1033 [Tn1696], and R135) was cloned and sequenced. In the case of R1033, it was shown that the aacC gene is coded by a precise insertion of 833 bp between the aadA promoter and its structural gene in a Tn21 related transposon (Tn1696). This insertion occurs at the same target sequence as that of the OXA-1 beta-lactamase gene insertion in Tn2603. Upstream of the aacC gene, we found an open reading frame (ORF) which is probably implicated in the site-specific recombinational events involved in the evolution of this family of genetic elements. These results provide additional confirmation of the role of Tn21 elements as naturally occurring interspecific transposition and expression cassettes.

Environmental risk factors for REM sleep behavior disorder: a multicenter case-control study

OBJECTIVE

Idiopathic REM sleep behavior disorder is a parasomnia characterized by dream enactment and is commonly a prediagnostic sign of parkinsonism and dementia. Since risk factors have not been defined, we initiated a multicenter case-control study to assess environmental and lifestyle risk factors for REM sleep behavior disorder.

METHODS

Cases were patients with idiopathic REM sleep behavior disorder who were free of dementia and parkinsonism, recruited from 13 International REM Sleep Behavior Disorder Study Group centers. Controls were matched according to age and sex. Potential environmental and lifestyle risk factors were assessed via standardized questionnaire. Unconditional logistic regression adjusting for age, sex, and center was conducted to investigate the environmental factors.

RESULTS

A total of 694 participants (347 patients, 347 controls) were recruited. Among cases, mean age was 67.7 ± 9.6 years and 81.0% were male. Cases were more likely to smoke (ever smokers = 64.0% vs 55.5%, adjusted odds ratio [OR] = 1.43, p = 0.028). Caffeine and alcohol use were not different between cases and controls. Cases were more likely to report previous head injury (19.3% vs 12.7%, OR = 1.59, p = 0.037). Cases had fewer years of formal schooling (11.1 ± 4.4 years vs 12.7 ± 4.3, p < 0.001), and were more likely to report having worked as farmers (19.7% vs 12.5% OR = 1.67, p = 0.022) with borderline increase in welding (17.8% vs 12.1%, OR = 1.53, p = 0.063). Previous occupational pesticide exposure was more prevalent in cases than controls (11.8% vs 6.1%, OR = 2.16, p = 0.008).

CONCLUSIONS

Smoking, head injury, pesticide exposure, and farming are potential risk factors for idiopathic REM sleep behavior disorder.

Purification and Characterization of Three Chitosanase Activities from Bacillus megaterium P1

Bacillus megaterium P1, a bacterial strain capable of hydrolyzing chitosan, was isolated from soil samples. Chitosan-degrading activity was induced by chitosan but not by its constituent d-glucosamine. Extracellular secretion of chitosanase reached levels corresponding to 1 U/ml under optimal conditions. Three chitosan-degrading proteins (chitosanases A, B, and C) were purified to homogeneity. Chitosanase A (43 kilodaltons) was highly specific for chitosan and represented the major chitosan-hydrolyzing species. Chitosanases B (39.5 kilodaltons) and C (22 kilodaltons) corresponded to minor activities and possessed comparable specific activities toward chitosan, chitin, and cellulose. Chitosanase A was active from pH 4.5 to 6.5 and was stable on the basis of activity up to 45 degrees C. The optimum temperature for enzymatic chitosan hydrolysis was 50 degrees C. Kinetic studies on chitosanase A suggest that the enzyme is substrate inhibited. The apparent K(m) and V(max) determined at 22 degrees C and pH 5.6 were 0.8 mg/ml and 280 U/mg, respectively. End products of chitosan hydrolysis by each of the three chitosanases were identified as glucosamine oligomers, similar to those obtained for previously reported chitosanase digestions.

Strenuous working conditions and musculo-skeletal disorders among female hospital workers

The relations between working conditions and various aspects of health among female hospital workers were studied in 26 departments of large hospitals in the Paris area in 1986; 90% of the workers of these departments filled in a questionnaire about their working conditions, sociodemographic characteristics and health in the previous 12 months and attended a medical examination. The study sample included 1505 women. The main cause of sick leave was musculoskeletal disorders and affected 16% of the women. Back pain was described by 47% of the women, and treatment for musculo-skeletal disorders by 28%. Three working conditions were considered to characterize the posture at work: standing more than six hours a day, bending over more than ten times per hour, and maintaining an uncomfortable posture. A cumulative posture index was constructed by adding for each worker the number of the working conditions to which she had been exposed. A cumulative lifting index was constructed in a similar way from the four following characteristics: lifting weights of more than 15 kg, lifting patients more than ten times a day, making beds normally or often, and pushing beds or trolleys more than ten minutes a day. A mixed index was then constructed associating the two previous ones. The relations between these indexes and musculoskeletal disorders (MSD) were studied after adjustment for potential confounders such as age, obesity, number of children, travel duration, sport practice, occupational level, number of years in the occupation, previous attack of back pain, and mental health (assessed by the score to the general health questionnaire). The logistic regressions of MSD indicators on the mixed index and other risk factors showed that MSD was about twice as frequent among women with a maximal load in posture and/or in lifting than among women with no more than one medium index (tiring posture or lifting). These facts support the necessity for improvement of the work load in hospitals.

Role of p97 and syntaxin 5 in the assembly of transitional endoplasmic reticulum

Transitional endoplasmic reticulum (tER) consists of confluent rough and smooth endoplasmic reticulum (ER) domains. In a cell-free incubation system, low-density microsomes (1.17 g cc(-1)) isolated from rat liver homogenates reconstitute tER by Mg(2+)GTP- and Mg(2+)ATP-hydrolysis-dependent membrane fusion. The ATPases associated with different cellular activities protein p97 has been identified as the relevant ATPase. The ATP depletion by hexokinase or treatment with either N-ethylmaleimide or anti-p97 prevented assembly of the smooth ER domain of tER. High-salt washing of low-density microsomes inhibited assembly of the smooth ER domain of tER, whereas the readdition of purified p97 with associated p47 promoted reconstitution. The t-SNARE syntaxin 5 was observed within the smooth ER domain of tER, and antisyntaxin 5 abrogated formation of this same membrane compartment. Thus, p97 and syntaxin 5 regulate assembly of the smooth ER domain of tER and hence one of the earliest membrane differentiated components of the secretory pathway.

Role of the ATP-binding domain of the human papillomavirus type 11 E1 helicase in E2-dependent binding to the origin

Replication of the genome of human papillomaviruses (HPV) is initiated by the recruitment of the viral E1 helicase to the origin of DNA replication by the viral E2 protein, which binds specifically to the origin. We determined, for HPV type 11 (HPV-11), that the C-terminal 296 amino acids of E1 are sufficient for interaction with the transactivation domain of E2 in the yeast two-hybrid system and in vitro. This region of E1 encompasses the ATP-binding domain. Here we have examined the role of this ATP-binding domain, and of ATP, on E2-dependent binding of E1 to the origin. Several amino acid substitutions in the phosphate-binding loop (P loop), which is implicated in binding the triphosphate moiety of ATP, abolished E2 binding, indicating that the structural integrity of this domain is essential for the interaction. The structural constraints imposed on the E1 P loop may differ between HPV-11 and bovine papillomavirus type 1 (BPV-1), since the P479S substitution that inactivates BPV-1 E1 is tolerated in the HPV-11 enzyme. Other substitutions in the E1 P loop, or in two other conserved motifs of the ATP-binding domain, were tolerated, indicating that ATP binding is not essential for interaction with E2. Nevertheless, ATP-Mg stimulated the E2-dependent binding of E1 to the origin in vitro. This stimulation was maximal at the physiological temperature (37 degrees C) and did not require ATP hydrolysis. In contrast, ATP-Mg did not stimulate the E2-dependent binding to the origin of an E1 protein containing only the C-terminal domain (353 to 649) or that of mutant E1 proteins with alterations in the DNA-binding domain. These results are discussed in light of a model in which the E1 ATP-binding domain is required for formation of the E2-binding surface and can, upon the binding of ATP, facilitate and/or stabilize the interaction of E1 with the origin.

The functional activity of alpha 1-proteinase inhibitor in bronchoalveolar lavage fluids from healthy human smokers and non-smokers

Cigarette smoking is an important risk factor for pulmonary emphysema. In vitro experiments document cigarette smoke-induced inactivation of alpha 1-proteinase inhibitor, a protein which is thought to protect the lung interstitium against the deleterious action of neutrophil elastase. To assess the relevance of this in in vitro findings, we have measured the functional activity of alpha 1-proteinase inhibitor collected by bronchoalveolar lavage from twenty healthy volunteers (10 heavy smokers and 10 non-smokers). The total inhibitor concentration was measured by radial immunodiffusion. The active inhibitor concentration was determined by virtue of its elastase inhibitory capacity. We used pure and active site-titrated porcine pancreatic elastase and a kinetic assay with succinyl-trialanine-p-nitroanilide in order to get reliable and accurate results. In smokers and in non-smokers the percentage of functionally active alpha 1-proteinase inhibitor in bronchoalveolar lavage fluid is 54 +/- 12 and 38 +/- 14%, respectively. This difference is not significant. Serum alpha 1-proteinase inhibitor is 100% active in both groups. Our data disagree with previous reports suggesting the presence of fully active alpha 1-proteinase inhibitor in bronchoalveolar lavage fluid of non-smokers and of partially active inhibitor in the lavage fluid of smokers.

Characterization of recombinant HPV6 and 11 E1 helicases: effect of ATP on the interaction of E1 with E2 and mapping of a minimal helicase domain

To better characterize the enzymatic activities required for human papillomavirus (HPV) DNA replication, the E1 helicases of HPV types 6 and 11 were produced using a baculovirus expression system. The purified wild type proteins and a version of HPV11 E1 lacking the N-terminal 71 amino acids, which was better expressed, were found to be hexameric over a wide range of concentrations and to have helicase and ATPase activities with relatively low values for K(m)(ATP) of 12 microm for HPV6 E1 and 6 microm for HPV11 E1. Interestingly, the value of K(m)(ATP) was increased 7-fold in the presence of the E2 transactivation domain. In turn, ATP was found to perturb the co-operative binding of E1 and E2 to DNA. Mutant and truncated versions of in vitro translated E1 were used to identify a minimal ATPase domain composed of the C-terminal 297 amino acids. This fragment was expressed, purified, and found to be fully active in ATP hydrolysis, single-stranded DNA binding, and unwinding assays, despite lacking the minimal origin-binding domain.

Chronic exposure to beta-hydroxybutyrate impairs insulin action in primary cultures of adult cardiomyocytes

Type 1 and type 2 diabetic patients often show elevated plasma ketone body concentrations. Because ketone bodies compete with other energetic substrates and reduce their utilization, they could participate in the development of insulin resistance in the heart. We have examined the effect of elevated levels of ketone bodies on insulin action in primary cultures of adult cardiomyocytes. Cardiomyocytes were cultured with the ketone body beta-hydroxybutyrate (beta-OHB) for 4 or 16 h, and insulin-stimulated glucose uptake was evaluated. Although short-term exposure to ketone bodies was not associated with any change in insulin action, our data demonstrated that preincubation with beta-OHB for 16 h markedly reduced insulin-stimulated glucose uptake in cardiomyocytes. This effect is concentration dependent and persists for at least 6 h after the removal of beta-OHB from the media. Ketone bodies also decreased the stimulatory effect of phorbol 12-myristate 13-acetate and pervanadate on glucose uptake. This diminution could not be explained by a change in either GLUT-1 or GLUT-4 protein content in cardiomyocytes. Chronic exposure to beta-OHB was associated with impaired protein kinase B activation in response to insulin and pervanadate. These results indicate that prolonged exposure to ketone bodies altered insulin action in cardiomyocytes and suggest that this substrate could play a role in the development of insulin resistance in the heart.

Transfusions enriched for W3/25+ helper/inducer T lymphocytes prevent spontaneous diabetes in the BB/W rat

Transfusions of spleen cells are known to prevent spontaneous autoimmune diabetes in susceptible BB/W rats, while T cell-depleted transfusions are ineffective. To characterize further the protective cell(s), we transfused young diabetes prone rats with splenocytes from diabetes resistant BB/W rats that were treated in vitro to enrich them in either OX8+ (suppressor/cytotoxic) T cells or W3/25+ (helper/inducer) T cells. Diabetes subsequently occurred in 19 of 29 (66%) recipients of OX8-enriched, W3/25-depleted cells and 20 of 37 (54%) controls, but in only 7 of 30 (23%) recipients of W3/25-enriched, OX8-depleted cells (p less than 0.005). Transfusion of spleen cells from diabetes resistant donor rats pretreated in vivo to deplete OX8+ cells also prevented diabetes in susceptible BB/W recipients. We conclude that transfusions of W3/25+ helper/inducer splenic T lymphocytes obtained from diabetes resistant animals prevent spontaneous diabetes in the BB/W rat.

Identification of domains of the human papillomavirus type 11 E1 helicase involved in oligomerization and binding to the viral origin

The E1 helicase of papillomavirus is required, in addition to host cell DNA replication factors, during the initiation and elongation phases of viral episome replication. During initiation, the viral E2 protein promotes the assembly of enzymatically active multimeric E1 complexes at the viral origin of DNA replication. In this study we used the two-hybrid system and chemical cross-linking to demonstrate that human papillomavirus type 11 (HPV11) E1 can self-associate in yeast and form hexamers in vitro in a reaction stimulated by single-stranded DNA. Self-association in yeast was most readily detected using constructs spanning the E1 C-terminal domain (amino acids 353 to 649) and was dependent on a minimal E1-E1 interaction region located between amino acids 353 and 431. The E1 C-terminal domain was also able to oligomerize in vitro but, in contrast to wild-type E1, did so efficiently in the absence of single-stranded DNA. Sequences located between amino acids 191 and 353 were necessary for single-stranded DNA to modulate oligomerization of E1 and were also required, together with the rest of the C terminus, for binding of E1 to the origin. Two regions within the C-terminal domain were identified as important for oligomerization: the ATP-binding domain and region A, which is located within the minimal E1-E1 interaction domain and is one of four regions of E1 that is highly conserved with the large T antigens of simian virus 40 and polyomavirus. Amino acid substitutions of highly conserved residues within the ATP-binding domain and region A were identified that reduced the ability of E1 to oligomerize and bind to the origin in vitro and to support transient DNA replication in vivo. These results support the notion that oligomerization of E1 occurs primarily through the C-terminal domain of the protein and is allosterically regulated by DNA and ATP. The bipartite organization of the E1 C-terminal domain is reminiscent of that found in other hexameric proteins and suggests that these proteins may oligomerize by a similar mechanism.

Transbronchial needle aspiration in the diagnosis of sarcoidosis

A total of 258 patients with suspected sarcoidosis underwent transbronchial needle aspiration lymph node biopsies and forceps bronchial biopsies during rigid bronchoscopy. Transbronchial needle aspiration biopsies revealed noncaseating granulomas in 66.3 percent of patients. When transbronchial needle aspiration biopsies were combined with forceps bronchial biopsies, the positive rate increased to 77.7 percent. No major complication occurred when using transbronchial needle aspiration. Rigid bronchoscopy with transbronchial needle aspiration biopsies appears to offer a sensitive and specific alternative to more invasive techniques used in the diagnosis of sarcoidosis.

The tus gene of Escherichia coli: autoregulation, analysis of flanking sequences and identification of a complementary system in Salmonella typhimurium

The tus gene of Escherichia coli encodes a DNA-binding protein that, when bound to terminator sites, blocks replication forks. One of these sites, TerB, is immediately upstream from tus, and we have determined that the 5' end of tus mRNA is in the TerB site, that tus is autoregulated and that pTus is a very low efficiency promoter. Analysis of the DNA upstream from tus and TerB indicates a set of sensor/regulator genes which are comparable to envZ/ompR. Although tus mutants exhibit no growth phenotype in laboratory conditions, Salmonella typhimurium and E. coli have nevertheless maintained similar termination systems. Sequence homology can be demonstrated by Southern hybridizations, and the systems also exhibit functional complementation: the Tus protein of S. typhimurium blocks DNA replication at the TerA site of E. coli.

Self-association of herpes simplex virus type 1 ICP35 is via coiled-coil interactions and promotes stable interaction with the major capsid protein

The ordered copolymerization of viral proteins to form the herpes simplex virus (HSV) capsid occurs within the nucleus of the infected cell and is a complex process involving the products of at least six viral genes. In common with capsid assembly in double-stranded DNA bacteriophages, HSV capsid assembly proceeds via the assembly of an outer capsid shell around an interior scaffold. This capsid intermediate matures through loss of the scaffold and packaging of the viral genomic DNA. The interior of the HSV capsid intermediate contains the viral protease and assembly protein which compose the scaffold. Proteolytic processing of these proteins is essential for and accompanies capsid maturation. The assembly protein (ICP35) is the primary component of the scaffold, and previous studies have demonstrated it to be capable of intermolecular association with itself and with the major capsid protein, VP5. We have defined structural elements within ICP35 which are responsible for intermolecular self-association and for interaction with VP5. Yeast (Saccharomyces cerevisiae) two-hybrid assays and far-Western studies with purified recombinant ICP35 mapped a core self-association domain between Ser165 and His219. Site-directed mutations in this domain implicate a putative coiled coil in ICP35 self-association. This coiled-coil motif is highly conserved within the assembly proteins of other alpha herpesviruses. In the two-hybrid assay the core self-association domain was sufficient to mediate stable self-association only in the presence of additional structural elements in either N- or C-terminal flanking regions. These regions also contain conserved sequences which exhibit a high propensity for alpha helicity and may contribute to self-association by forming additional short coiled coils. Our data supports a model in which ICP35 molecules have an extended conformation and associate in parallel orientation through homomeric coiled-coil interactions. In additional two-hybrid experiments we evaluated ICP35 mutants for association with VP5. We discovered that in addition to the C-terminal 25 amino acids of ICP35, previously shown to be required for VP5 binding, an additional upstream region was required. This region is between Ser165 and His234 and contains the core self-association domain. Site-directed mutations and construction of chimeric molecules in which the self-association domain of ICP35 was replaced by the GCN4 leucine zipper indicated that this region contributes to VP5 binding through mediating self-association of ICP35 and not through direct binding interactions. Our results suggest that self-association of ICP35 strongly promotes stable association with VP5 in vivo and are consistent with capsid formation proceeding via formation of stable subassemblies of ICP35 and VP5 which subsequently assemble into capsid intermediates in the nucleus.

Identification of domains of the HPV11 E1 protein required for DNA replication in vitro

The HPV E1 and E2 proteins along with cellular factors, are required for replication of the viral genome. In this study we show that in vitro synthesized HPV11 E1 can support DNA replication in a cell-free system and is able to cooperate with E2 to recruit the host polymerase alpha primase to the HPV origin in vitro. Deletion analysis revealed that the N-terminal 166 amino acids of E1, which encompass a nuclear localization signal and a cyclin E-binding motif, are dispensable for E1-dependent DNA replication and for recruitment of pol alpha primase to the origin in vitro. A shorter E1 protein lacking the N-terminal 190 amino acids supported cell-free DNA replication at less than 25% the efficiency of wild-type E1 and was active in the pol alpha primase recruitment assay. An even shorter E1 protein lacking a functional DNA-binding domain due to a truncation of the N-terminal 352 amino acids was inactive in both assays despite the fact that it retains the ability to associate with E2 or pol alpha primase in the absence of ori DNA. We provide additional functional evidence that E1 interacts with pol alpha primase through the p70 subunit of the complex by showing that p70 can be recruited to the HPV origin by E1 and E2 in vitro, that the domain of E1 (amino acids 353-649) that binds to pol alpha primase in vitro is the same as that needed for interaction with p70 in the yeast two-hybrid system, and that exogenously added p70 competes with the interaction between E1 and pol alpha primase and inhibits E1-dependent cell-free DNA replication. On the basis of these results and the observation that pol alpha primase competes with the interaction between E1 and E2 in solution, we propose that these three proteins assemble at the origin in a stepwise process during which E1, following its interaction with E2, must bind to DNA prior to interacting with pol alpha primase.

Induction of LFA-1 independent human B cell proliferation and differentiation by binding of CD40 with its ligand

Engagement of CD40 on resting B cells in the presence of IL-4 triggers B cell proliferation, differentiation and homotypic adhesion. This study was designed to investigate the role of LFA-1/ICAM-1 interactions in homotypic adhesion and proliferation of CD40-activated human B lymphocytes. Freshly isolated B cells were cultured in vitro in the presence of IL-4 and of L cells expressing CD40L, the CD40 ligand. The addition to the culture medium of LFA-1 and ICAM-1 antibodies inhibited homotypic B lymphocyte adhesion. However, these antibodies failed to affect B lymphocyte proliferation and antibody production. These results indicate that aggregation and proliferation are independent events although both induced by CD40 activation.

The Cdc42/Rac1 regulator CdGAP is a novel E-cadherin transcriptional co-repressor with Zeb2 in breast cancer

The loss of E-cadherin causes dysfunction of the cell-cell junction machinery, which is an initial step in epithelial-to-mesenchymal transition (EMT), facilitating cancer cell invasion and the formation of metastases. A set of transcriptional repressors of E-cadherin (CDH1) gene expression, including Snail1, Snail2 and Zeb2 mediate E-cadherin downregulation in breast cancer. However, the molecular mechanisms underlying the control of E-cadherin expression in breast cancer progression remain largely unknown. Here, by using global gene expression approaches, we uncover a novel function for Cdc42 GTPase-activating protein (CdGAP) in the regulation of expression of genes involved in EMT. We found that CdGAP used its proline-rich domain to form a functional complex with Zeb2 to mediate the repression of E-cadherin expression in ErbB2-transformed breast cancer cells. Conversely, knockdown of CdGAP expression led to a decrease of the transcriptional repressors Snail1 and Zeb2, and this correlated with an increase in E-cadherin levels, restoration of cell-cell junctions, and epithelial-like morphological changes. In vivo, loss of CdGAP in ErbB2-transformed breast cancer cells impaired tumor growth and suppressed metastasis to lungs. Finally, CdGAP was highly expressed in basal-type breast cancer cells, and its strong expression correlated with poor prognosis in breast cancer patients. Together, these data support a previously unknown nuclear function for CdGAP where it cooperates in a GAP-independent manner with transcriptional repressors to function as a critical modulator of breast cancer through repression of E-cadherin transcription. Targeting Zeb2-CdGAP interactions may represent novel therapeutic opportunities for breast cancer treatment.

The elastase inhibitory capacity and the alpha 1-proteinase inhibitor and bronchial inhibitor content of bronchoalveolar lavage fluids from healthy subjects

Pulmonary emphysema is currently thought to be due to an elastase-antielastase imbalance with resultant destruction of alveolar structures. The present study was aimed at testing whether alpha 1-proteinase inhibitor (alpha 1 PI) is the major component of the antielastase screen of the lower respiratory tract of healthy subjects. Bronchoalveolar lavage was performed in 8 nonsmokers (27.8 +/- 3.8 years) and 9 smokers (25 +/- 0.96 years). The lavage fluids were tested for leukocyte and pancreatic elastase inhibitory capacity (LEIC and PEIC) and immunoreactive alpha 1 PI and bronchial inhibitor (brI) content. The mean +/- s.e.m. levels of LEIC, PEIC, alpha 1 PI and brI were 0.16 +/- 0.039, 0.042 +/- 0.006, 0.09 +/- 0.007 and 0.013 +/- 0.002 mol/mol albumin, respectively. Thus, on the average, the molar concentration of brI was about 14% that of alpha 1 PI. The difference between LEIC and alpha 1 PI did not reach statistical significance (P = 0.0503). The PEIC was however significantly lower than the alpha 1 PI levels (P less than 0.05), indicating that the lavage fluids contained both active and inactive alpha 1 PI. Nonsmokers and smokers did not differ in their LEIC, PEIC, alpha 1 PI and brI levels. When the data were examined on an individual basis, the subjects could be divided into 2 groups: group I (n = 9; 3 nonsmokers, 6 smokers) whose LEIC/alpha 1 PI molar ratios were higher than unity and group II (n = 8; 5 nonsmokers, 3 smokers) whose LEIC/alpha 1 PI molar ratios were equal or lower than unity. Group I subjects had significantly higher LEIC values (0.26 +/- 0.05 mol elastase inhibited/mol albumin) than group II individuals (0.055 +/- 0.006; P less than 0.001) but the two groups had similar levels of immunoreactive alpha 1 PI (0.09 and 0.08 mol alpha 1 PI/mol albumin for group I and II, respectively), functionally active alpha 1 PI (percentage of active alpha 1 PI: 53% and 37% for group I and II, respectively) and immunoreactive brI (0.016 and 0.010 mol brI/mol albumin for group I and II, respectively). These results suggested that the lavage fluids from group I contained significant amounts of undefined leukocyte elastase inhibitor(s). Gel filtration of a lavage fluid from group I showed that the undefined elastase inhibitor(s) co-eluted with brI. Most of the lavage fluids were still able to inhibit leukocyte elastase following removal of alpha 1 PI by perchloric acid precipitation.(ABSTRACT TRUNCATED AT 400 WORDS)