Hazard Group 3 agent decontamination using hydrogen peroxide vapour in a class III microbiological safety cabinet

AIMS

This study investigated the efficacy of hydrogen peroxide vapour (HPV) at inactivating hazard group 3 bacteria that have been presented dried from their growth medium to present a realistic challenge.

METHODS AND RESULTS

Hydrogen peroxide vapour technology (Bioquell) was used to decontaminate a class III microbiological safety cabinet containing biological indicators (BIs) made by drying standard working suspensions of the following agents: Bacillus anthracis (Ames) spores, Brucella abortus (strain S99), Burkholderia pseudomallei (NCTC 12939), Escherichia coli O157 ST11 (NCTC 12079), Mycobacterium tuberculosis (strain H37Rv) and Yersinia pestis (strain CO92) on stainless steel coupons. Extended cycles were used to expose the agents for 90 min. The HPV cycle completely inactivated B. anthracis spores, B. abortus, B. pseudomallei, E. coli O157 and Y. pestis when BIs were processed using quantitative and qualitative methods. Whilst M. tuberculosis was not completely inactivated, it was reduced by 4 log₁₀ from a starting concentration of 10⁶ colony-forming units.

CONCLUSIONS

This study demonstrates that HPV is able to inactivate a range of HG3 agents at high concentrations with associated organic matter, but M. tuberculosis showed increased resistance to the process.

SIGNIFICANCE AND IMPACT OF THE STUDY

This publication demonstrates that HPV can inactivate HG3 agents that have an organic load associated with them. It also shows that M. tuberculosis has higher resistance to HPV than other agents. This shows that an appropriate BI to represent the agent of interest should be chosen to demonstrate a decontamination is successful.

Sampling and inactivation of wet disseminated spores from flooring materials, using commercially available robotic vacuum cleaners

AIMS

Four commercially available robotic vacuum cleaners were assessed for sampling efficiency of wet disseminated Bacillus atrophaeus spores on carpet, polyvinyl chloride (PVC) and laminate flooring. Furthermore, their operability was evaluated and decontamination efficiency of one robot was assessed, using a sodium hypochlorite solution.

METHODS AND RESULTS

In an environmental chamber, robots self-navigated around 4 m² of flooring containing a single contaminated 0·25 m² tile (c. 10⁴ spores per cm² ). Contamination levels at predetermined locations were assessed by macrofoam swabs (PVC and laminate) or water soluble tape (carpet), before and after sampling. Robots were dismantled postsampling and spore recoveries assessed. Aerosol contamination was also measured during sampling. Robot sampling efficiencies were variable, however, robots recovered most spores from laminate (up to 17·1%), then PVC and lastly the carpet. All robots spread contamination from the 'hotspot' (all robots spread <0·6% of the contamination to other areas) and became surface contaminated. Spores were detected at low levels during air sampling (<5·6 spores per litre). Liquid decontamination inactivated 99·1% of spores from PVC.

CONCLUSIONS

Robotic vacuum cleaners show promise for both sampling and initial decontamination of indoor flooring.

SIGNIFICANCE AND IMPACT OF THE STUDY

In the event of a bioterror incident, e.g. deliberate release of Bacillus anthracis spores, areas require sampling to determine the magnitude and extent of contamination, and to establish decontamination efficacy. In this study, we investigate robotic sampling methods against high concentrations of bacterial spores applied by wet deposition to different floorings, contamination spread to other areas, potential transfer of spores to the operators and assessment of a wet vacuum robot for spore inactivation. The robots' usability was evaluated and how they can be employed in real life scenarios. This will help to reduce the economic cost of sampling and the risk to sampling/decontamination teams.

Persistence of influenza on surfaces

BACKGROUND

Close contact transmission (either direct or large droplet/droplet nuclei) is considered the main driver of influenza outbreaks but there is limited information regarding the role of fomites in transmission.

AIM

To investigate the surface stability of influenza strains and thereby the role of fomites in transmission.

METHODS

The viability and quantitative reverse transcription-polymerase chain reaction (qt-RT-PCR) signal of five influenza strains (A/PR/8/34/H1N1, A/Cal/7/09/H1N1, A/Cal/4/09/H1N1, A/Sol/54/06/H1N1, and A/Bris/59/07/H1N1) seeded on to three surfaces (cotton, microfibre, and stainless steel) were assessed over time. Coupons of material were seeded with 10μL of a 10⁶-10⁸pfu/mL suspension of cell culture-derived virus stock supplemented with 0.3% bovine serum albumin. Coupons were assayed by plaque assay and qt-RT-PCR at 1, 24h, and weekly for seven weeks using a vortex-mixing elution method.

FINDINGS

Viable virus was detected from coupons for up to two weeks (stainless steel) and one week (cotton and microfibre), whereas detection of viruses by PCR was made for the entire seven-week study period. No strain differences were found. Ninety-nine percent reduction values (as a function of the seeding stock) were determined to be 17.7h for cotton (R²=0.86), 34.3h for microfibre (R²=0.80), and 174.9h for stainless steel (R²=0.98).

CONCLUSION

Viable influenza was recovered from surfaces for up to two weeks. By contrast, influenza could be detected by PCR for more than seven weeks. These results have important implications for determining infection control protocols, cleaning regimes and sampling methods in healthcare settings.

Is there an infection risk when playing drums contaminated with Bacillus anthracis?

AIMS

This study aims to investigate the aerosol release of a Bacillus anthracis spore surrogate from two different types of drums while playing, by; (i) quantifying the number of spores aerosolized during playing; (ii) investigating spore recovery from drums over long time periods, and (iii) measuring differences between (i) and (ii) for two different drums types.

METHODS AND RESULTS

Two African drums were contaminated with Bacillus atrophaeus spores then sampled and played by hand over a number of days. During playing three air samplers were used to collect any aerosols generated, the choice of air samplers (Casella slit sampler, all glass impinger and six-stage Andersen sampler) allowed for characterization of the aerosols produced.

CONCLUSIONS

Spore contamination of drums was found to be long-lasting with a small percentage of the spores being detached and aerosolized during drumming. The results of these studies have been used for a quantitative risk assessment of playing drums contaminated with B. anthracis spores.

SIGNIFICANCE AND IMPACT OF THE STUDY

This demonstrates that the risk of inhalational exposure while playing drums contaminated with the levels linked to the US and UK cases is very low and that the resulting cases of inhalational anthrax can be explained by being unusual events involving highly susceptible persons.

Responding to biological incidents--what are the current issues in remediation of the contaminated environment?

Since 2000 there have been a number of biological incidents resulting in environmental contamination with Bacillus anthracis, the causative agent of anthrax. These incidents include the US anthrax attacks in 2001, the US and UK drumming incidents in 2006-2008 and more recently, anthrax contamination of heroin in 2009/2010 and 2012/2013. Remediation techniques used to return environments to normal have varied between incidents, with different decontamination technologies being employed. Many factors need to be considered before a remediation strategy or recovery option can be implemented, including; cost, time (length of application), public perception of risk, and sampling strategies (and results) to name a few. These incidents have demonstrated that consolidated guidance for remediating biologically contaminated environments in the aftermath of a biological incident was required. The UK Recovery Handbook for Biological Incidents (UKRHBI) is a project led by Public Health England (PHE), formerly the Health Protection Agency (HPA) to provide guidance and advice on how to remediate the environment following a biological incident or outbreak of infection, and is expected to be published in 2015.

Whispering gallery mode diamond resonator

We demonstrate a nearly spherical diamond whispering gallery mode resonator with quality factor (Q factor) Q=2.4×10(7) limited by material loss approaching α=4×10(-3) cm(-1). The Q factor does not depend on the wavelength: it is approximately the same at 1319 and 1550 nm. Resonators with this range of Q (<10 MHz at 1550 nm wavelength) are attractive for laser locking and stabilization. Applications such as stable compact optical comb generators as well as Raman optical frequency shifters will be feasible with further improvement of the material.

Demographic differences among populations of Northern Map Turtles (Graptemys geographica) in intact and fragmented sites

Habitat fragmentation is a leading cause of reptile declines worldwide. We examined demographic differences between populations of Northern Map Turtles, Graptemys geographica (Le Sueur, 1817), inhabiting intact and fragmented sites along the Trent–Severn Waterway (TSW) in Ontario over two field seasons. We examined population densities, sex ratios, body size, and growth rates in two control sites and two fragmented sites (where the waterway is disrupted by dams). We predicted that population density would be higher in control sites, and that sex ratios would differ among sites. Abundance was greater than expected, but densities could not be compared owing to a lack of recaptures. Sex ratios in control sites were slightly male-biased and were significantly female-biased in fragmented sites. Turtles in fragmented habitats were significantly smaller than those in control habitats. Estimated growth rates of juveniles and males were significantly reduced in fragmented populations compared with controls. We hypothesize that habitat alterations in fragmented sites are differentially affecting demographic classes because of the intersexual niche divergence observed in Map Turtles. We emphasize the need for further research to examine the interactions between habitat alteration and invasive species and the effects they are having on Northern Map Turtle populations.

Laboratory methods for assessing vaccine potency retained in aerosol outputs from nebulizers: application to World Health Organization measles aerosol project

BACKGROUND

Laboratory methods for measuring vaccine potency of nebulized aerosol are required to support clinical trials of measles aerosol vaccination.

METHODS

Measles vaccine containing the Edmonston Zagreb virus strain was reconstituted in sodium fluoride as tracer and nebulized from three devices. Emitted aerosol was collected using an impinger. Aliquots were removed from the impinger chamber for vaccine virus plaque assay and for fluoride measurement to determine aerosol output.

RESULTS

Vaccine potency retention results were adjusted to take into account the effect of aerosol output on estimates. Adjusted potency of nebulized vaccine ranged from 88% to 102%.

CONCLUSIONS

New laboratory methods to measure aerosol vaccine potency retention were reliable and accurate. The results demonstrated that Edmonston Zagreb vaccine remains robust during aerosolisation and imply that this is a viable candidate for further evaluation in the measles aerosol project.

Hospital and community acquired infection and the built environment--design and testing of infection control rooms

Negative-pressure isolation rooms are required to house patients infected with agents transmissible by the aerosol route in order to minimise exposure of healthcare workers and other patients. Housing patients in a separate room provides a barrier which minimises any physical contact with other patients. An isolation room held at negative pressure to reduce aerosol escape and a high air-change rate to allow rapid removal of aerosols can eliminate transmission of infectious aerosols to those outside the room. However, badly designed and/or incorrectly operating isolation rooms have been shown to place healthcare workers and other patients at risk from airborne diseases such as tuberculosis. Few standards are available for the design of isolation rooms and no pressure differential or air-change rates are specified. Techniques such as aerosol particle tracer sampling and computational fluid dynamics can be applied to study the performance of negative-pressure rooms and to assess how design variables can affect their performance. This should allow cost-effective designs for isolation rooms to be developed. Healthcare staff should be trained to understand how these rooms operate and there should be systems in place to ensure they are functioning correctly.

Nuclear and cytosolic calcium are regulated independently

Nuclear calcium (Ca(2+)) regulates a number of important cellular processes, including gene transcription, growth, and apoptosis. However, it is unclear whether Ca(2+) signaling is regulated differently in the nucleus and cytosol. To investigate this possibility, we examined subcellular mechanisms of Ca(2+) release in the HepG2 liver cell line. The type II isoform of the inositol 1,4,5-trisphosphate (InsP(3)) receptor (InsP(3)R) was expressed to a similar extent in the endoplasmic reticulum and nucleus, whereas the type III InsP(3)R was concentrated in the endoplasmic reticulum, and the type I isoform was not expressed. Ca(2+) signals induced by low InsP(3) concentrations started earlier or were larger in the nucleus than in the cytosol, indicating higher sensitivity of nuclear Ca(2+) stores for InsP(3). Nuclear InsP(3)R channels were active at lower InsP(3) concentrations than InsP(3)R from cytosol. Enriched expression of type II InsP(3)R in the nucleus results in greater sensitivity of the nucleus to InsP(3), thus providing a mechanism for independent regulation of Ca(2+)-dependent processes in this cellular compartment.

Cytotoxic T-cell activity is not detectable in Venezuelan equine encephalitis virus-infected mice

Previously published research has established that the immune response to the Venezuelan equine encephalitis virus (VEEV) vaccine strain TC-83 is Th 1-mediated, with local activation of both CD4+ and CD8+ T cells. This suggests that cytotoxic lymphocytes CTL may play a role in protection against virulent VEEV. Studies involving a variety of immunisation schedules with either TC-83 or strain CAAR 508 (serogroup 5) of VEEV, and six different haplotypes of mice, failed to reveal functional CTL activity against VEEV-infected targets in secondary antigen-stimulated lymphocyte cultures from either the draining lymph nodes (LN) or spleen. Nor were VEEV-specific CTL detected after immunisation of mice (three haplotypes) with recombinant vaccinia viruses (VV) expressing either the non-structural (nsP1-4) or the structural (C-E3-E2-6K-E1) genes of TC-83. Reciprocal experiments in which mice were immunised with TC-83, and their lymphocytes tested against VV recombinant-infected targets also failed to detect CTL activity. These data suggest that VEEV infection of mice does not elicit detectable CTL activity, and that CTL are unlikely to play a role in protection against virulent VEEV.

Co-immunisation with a plasmid DNA cocktail primes mice against anthrax and plague

The protective antigen (PA) of Bacillus anthracis and the V antigen of Yersinia pestis are potent immunogens and candidate vaccine sub-units. When plasmid DNA encoding either PA or V antigen was used to immunise the Balb/c mouse, a low serum IgG titre was detected (log (10)1.0 or less) which was slightly increased by boosting with plasmid DNA. However, when mice immunised with plasmid DNA were later boosted with the respective recombinant protein, a significant increase in titre (up to 100-fold) was observed. Mice primed with a combination of each plasmid and boosted with a combination of the recombinant proteins, were fully protected (6/6) against challenge with Y. pestis. This compared favourably with mice primed only with plasmid DNA encoding the V antigen and boosted with rV, which were partially protected (3/6) against homologous challenge or with mice primed and boosted with plasmid DNA encoding the V antigen which were poorly protected (1/6). Combined immunisation with the two plasmid DNA constructs followed by boosting with a combination of the encoded recombinant proteins enhanced the protective immune response to Y. pestis compared with priming only with plasmid DNA encoding the V antigen and boosting with rV. This enhancement may be due to the effect of CpG motifs known to be present in the plasmid DNA construct encoding PA.

SHP-2 complex formation with the SHP-2 substrate-1 during C2C12 myogenesis

Myogenesis is a highly ordered process that involves the expression of muscle-specific genes, cell-cell recognition and multinucleated myotube formation. Although protein tyrosine kinases have figured prominently in myogenesis, the involvement of tyrosine phosphatases in this process is unknown. SHP-2 is an SH2 domain-containing tyrosine phosphatase, which positively regulates growth and differentiation. We show that in C2C12 myoblasts, SHP-2 becomes upregulated early on during myogenesis and associates with a 120 kDa tyrosyl-phosphorylated complex. We have identified that the 120 kDa complex consists of the SHP-2 substrate-1 (SHPS-1) and the Grb2-associated binder-1 (Gab-1). SHPS-1, but not Gab-1, undergoes tyrosyl phosphorylation and association with SHP-2 during myogenesis, the kinetics of which correlate with the expression of MyoD. Either constitutive expression or inducible activation of MyoD in 10T½ fibroblasts promotes SHPS-1 tyrosyl phosphorylation and its association with SHP-2. It has been shown that p38 mitogen-activated protein kinase (MAPK) activity is required for the expression/activation of MyoD and MyoD-responsive genes. Inhibition of p38 MAPK by SB203580 in differentiating C2C12 myoblasts blocks MyoD expression, SHPS-1 tyrosyl phosphorylation and the association of SHPS-1 with SHP-2. These data suggest that SHPS-1/SHP-2 complex formation is an integral signaling component of skeletal muscle differentiation.

Microbial aerosols in general dental practice

OBJECTIVE

To measure the concentration of microbial aerosols in general dental practices and to use this information to carry out quantitative microbiological risk assessments.

METHODOLOGY

Microbial air sampling was carried out continuously during 12 treatment sessions in 6 general dental practices in the South West of England.

RESULTS

The microbial aerosol concentration in treatment rooms was generally less than 10(3) colony forming units per cubic metre of air (cfu x m(-3)). However, in 6 out of the 12 visits, at least one peak concentration with much higher numbers of bacteria was detected. The peak concentrations were associated with increased recoveries of presumptive oral streptococci suggesting these aerosols originated from the mouths of patients. These aerosol peaks dissipated within 30 minutes and no dissemination into waiting areas was detected. The peak concentrations were associated with mechanical scaling procedures (47% of procedures giving rise to a peak) and to a lesser extent by cavity preparation (11%). No aerosolised blood was detected.

CONCLUSIONS

The data have been used to generate a framework for quantifying risk of exposure of staff to aerosolised microbial pathogens in general dental practice. For example, dentists and their assistants may have a slightly higher risk of exposure to Mycobacterium tuberculosis than the general public. The use of face seal masks that have been shown to protect against aerosolised micro-organisms may reduce this exposure.

An immunological profile of Balb/c mice protected from airborne challenge following vaccination with a live attenuated Venezuelan equine encephalitis virus vaccine

The live attenuated vaccine strain of Venezuelan equine encephalitis virus (VEEV), TC-83, protects mice against challenge (subcutaneous and aerosol) with virulent VEEV but is not suitable for widescale human use. Elucidation of the immune response profile of protected mice should assist in the development of an improved vaccine. We determined the optimum dose of TC-83 required to consistently protect Balb/c mice from airborne challenge with the virulent Trinidad Donkey strain of VEEV and studied the development of humoral and cellular immune responses in protected mice between 6 h and 21 days post-vaccination. The most dramatic immune responses occurred in draining lymph nodes 24 h following vaccination with increased levels of activated B cells and T cells of both CD4(+) and CD8(+) subtypes. Activated monocyte/macrophages and natural killer cells were also seen between 6 h and 7 days post-vaccination. Serum contained detectable VEEV-specific IgG on day 5 post-vaccination with titres continuing to rise on days 7, 14 and 21. Isotypes of IgG measured on days 7 and 21 were predominantly of the IgG2a subclass, indicating that the immune response was Th1-mediated. Cytokine mRNA was quantified by RT-PCR and revealed production of the Th1 cytokine IFN-gamma and the inflammatory cytokine TNF-alpha, whereas the Th2 cytokine IL4 was not detected above control levels at any of the time points studied. This data describes key cellular immune responses at early times post-vaccination and is consistent with previous data demonstrating protection against aerosol challenge with VEEV in the absence of detectable levels of specific IgG or IgA antibody.

Survival of mycobacterial species in aerosols generated from artificial saliva

Tuberculosis is transmitted primarily by the aerosol route and the aim of this study was to measure the ability of pathogenic mycobacteria to survive in aerosols generated from artificial saliva. Aerosols of Mycobacterium avium, Mycobacterium intracellulare and Mycobacterium tuberculosis were generated and maintained in air under controlled conditions using a Henderson apparatus and a rotating drum. There were no differences in aerosol survival between the three species, and all had a poor survival rate over a period of 1 h. These data confirm epidemiological studies that close and prolonged contact with a TB patient is required for transmission of infection.

Microbial biofilm formation and contamination of dental-unit water systems in general dental practice

Dental-unit water systems (DUWS) harbor bacterial biofilms, which may serve as a haven for pathogens. The aim of this study was to investigate the microbial load of water from DUWS in general dental practices and the biofouling of DUWS tubing. Water and tube samples were taken from 55 dental surgeries in southwestern England. Contamination was determined by viable counts on environmentally selective, clinically selective, and pathogen-selective media, and biofouling was determined by using microscopic and image analysis techniques. Microbial loading ranged from 500 to 10(5) CFU. ml(-1); in 95% of DUWS water samples, it exceeded European Union drinking water guidelines and in 83% it exceeded American Dental Association DUWS standards. Among visible bacteria, 68% were viable by BacLight staining, but only 5% of this "viable by BacLight" fraction produced colonies on agar plates. Legionella pneumophila, Mycobacterium spp., Candida spp., and Pseudomonas spp. were detected in one, five, two, and nine different surgeries, respectively. Presumptive oral streptococci and Fusobacterium spp. were detected in four and one surgeries, respectively, suggesting back siphonage and failure of antiretraction devices. Hepatitis B virus was never detected. Decontamination strategies (5 of 55 surgeries) significantly reduced biofilm coverage but significantly increased microbial numbers in the water phase (in both cases, P < 0.05). Microbial loads were not significantly different in DUWS fed with soft, hard, deionized, or distilled water or in different DUWS (main, tank, or bottle fed). Microbiologically, no DUWS can be considered "cleaner" than others. DUWS deliver water to patients with microbial levels exceeding those considered safe for drinking water.

Differential role of beta(1C) and beta(1A) integrin cytoplasmic variants in modulating focal adhesion kinase, protein kinase B/AKT, and Ras/Mitogen-activated protein kinase pathways

The integrin cytoplasmic domain modulates cell proliferation, adhesion, migration, and intracellular signaling. The beta(1) integrin subunits, beta(1C) and beta(1A), that contain variant cytoplasmic domains differentially affect cell proliferation; beta(1C) inhibits proliferation, whereas beta(1A) promotes it. We investigated the ability of beta(1C) and beta(1A) to modulate integrin-mediated signaling events that affect cell proliferation and survival in Chinese hamster ovary stable cell lines expressing either human beta(1C) or human beta(1A). The different cytodomains of either beta(1C) or beta(1A) did not affect either association with the endogenous alpha(2), alpha(V), and alpha(5) subunits or cell adhesion to fibronectin or TS2/16, a mAb to human beta(1). Upon engagement of endogenous and exogenous integrins by fibronectin, cells expressing beta(1C) showed significantly inhibited extracellular signal-regulated kinase (ERK) 2 activation compared with beta(1A) stable cell lines. In contrast, focal adhesion kinase phosphorylation and Protein Kinase B/AKT activity were not affected. Selective engagement of the exogenously expressed beta(1C) by TS2/16 led to stimulation of Protein Kinase B/AKT phosphorylation but not of ERK2 activation; in contrast, beta(1A) engagement induced activation of both proteins. We show that Ras activation was strongly reduced in beta(1C) stable cell lines in response to fibronectin adhesion and that expression of constitutively active Ras, Ras 61 (L), rescued beta(1C)-mediated down-regulation of ERK2 activation. Inhibition of cell proliferation in beta(1C) stable cell lines was attributable to an inhibitory effect of beta(1C) on the Ras/MAP kinase pathway because expression of activated MAPK kinase rescued beta(1C) antiproliferative effect. These findings show that the beta(1C) variant, by means of a unique signaling mechanism, selectively inhibits the MAP kinase pathway by preventing Ras activation without affecting either survival signals stimulated by integrins or cellular interactions with the extracellular matrix. These findings highlight a role for beta(1)-specific cytodomain sequences in maintaining an intracellular balance of proliferation and survival signals.

Gene gun mediated vaccination is superior to manual delivery for immunisation with DNA vaccines expressing protective antigens from Yersinia pestis or Venezuelan Equine Encephalitis virus

Plasmids expressing the V antigen of Yersinia pestis or the E2 glycoprotein of Venezuelan Equine Encephalitis (VEE) virus were used to vaccinate mice by intra-dermal or intra-muscular injection, or by particle-mediated bombardment using the Helios gene gun. After two immunizations, groups of mice which had received 4 microg doses of plasmid DNA using the gene gun had IgG levels which were higher than in other groups manually immunised with 12-fold more plasmid DNA. The immunoglobulin isotype profile was predominantly IgG1 following inoculation with either plasmid. Our results indicate that gene gun mediated vaccination can be used to increase the magnitude of the immune response to both bacterial and viral antigens expressed by plasmid DNA.

Anaphylaxis during caesarean section in a patient with undiagnosed placenta accreta: it never rains but it pours!

Published guidelines exist for the management and investigation of suspected anaphylactic reactions associated with anaesthesia. We report a woman who had a life-threatening anaphylactic reaction during caesarean section under spinal anaesthesia, complicated by undiagnosed placenta accreta. We discuss the particular problems of the case and the practical difficulties of testing survivors of anaphylaxis: despite following the recommendations, we have been unable to identify the cause.

Expression of a recombinant form of the V antigen of Yersinia pestis, using three different expression systems

Yersinia pestis, the causative organism of plague, produces V antigen (LcrV), a bifunctional protein with regulatory and virulence roles that has been shown to be highly protective against a plague challenge. A combined sub-unit vaccine, comprising recombinant V and Fraction 1 antigens is currently being developed. We report here the expression and purification of recombinant V antigen (rV) using three different expression systems: the N-terminal GST fusion pGEX-5X-2 and pGEX-6P-2 systems from Pharmacia Biotech, and the C-terminal CBD fusion (IMPACT I) system from New England Biolabs. After cleavage from the carrier protein, the yields of rV were 25 mg l(-1) (pGEX-5X-2), 31 mg l(-1) (pGEX-6P-2) and 0.75 mg l(-1) (IMPACT I). All of the recombinant proteins were immunogenic in mice, although there were some differences in their protective efficacy against subcutaneous challenge with Y. pestis. Whilst rV antigen derived from the IMPACT I and pGEX-6P-2 systems and given in two immunising doses protected fully against challenge with 1 x 10(7) colony forming units (cfu) of Y. pestis, there was breakthrough in protection against 1 x 10(5) cfu of Y. pestis in animals immunised twice with rV from the pGEX-5X-2 system. From this study, the pGEX-6P-2 has been selected for the production of rV as a vaccine component. The pGEX-6P-2 system utilises a GST tagged PreScission Protease (a recombinant human rhinovirus 3C protease) to cleave the fusion protein, thereby allowing efficient removal of the enzyme from the final product. In addition, the enzyme is not of animal origin, therefore making it suitable for vaccine production.

Presentation of protective antigen to the mouse immune system: immune sequelae

Protective antigen (PA), the major protective component of the existing vaccine, is a potent immunogen. Protective antigen in alhydrogel induced a high serum IgG titre (> log10 4) in both the C57B16 and Balb/c mouse and the predominant subclass of antibody induced was IgG1, indicating that the response to PA was predominantly Th2 directed. When plasmid DNA encoding PA was used to immunize the Balb/c mouse, a low serum IgG titre was detected (</=log10 1), which was slightly increased by boosting with plasmid DNA. However, when mice immunized with plasmid DNA were later boosted with rPA, a significant and rapid increase in titre (up to threefold) was observed. Priming mice with PA-encoding plasmid DNA may be a mechanism of enhancing and accelerating the immune response to PA.

Recombinant vaccinia viruses protect against Clostridium perfringens alpha-toxin

Recombinant vaccinia viruses that expressed the nontoxic C-domain of Clostridium perfringens alpha-toxin were constructed. The J2R (thymidine kinase [TK] gene) and B13R (serpin 2 [SPI-2] gene) loci were used as insertion sites for the clostridial DNA, and expression of the foreign protein was measured in each case. A double recombinant that encoded the alpha-toxin truncate at the B13R locus and the protective antigen of Bacillus anthracis at the J2R locus was also constructed. Although differences in expression of the alpha-toxin C-domain were recorded, all of the vaccinia recombinants protected mice against a lethal challenge with alpha-toxin demonstrating that a recombinant vaccinia virus can be used to provide protection against a toxin challenge that is known to be solely antibody mediated.

Improved protection against Venezuelan equine encephalitis by genetic engineering of a recombinant vaccinia virus

An improved vaccine is needed against Venezuelan equine encephalitis (VEE) virus because the existing live attenuated vaccine, TC-83, causes a high incidence of adverse effects, and the Formalin-inactivated vaccine, C-84, does not protect against airborne infection. A recombinant vaccine had previously been constructed in which the VEE structural proteins were expressed by vaccinia virus. Although protection against subcutaneous challenge with VEE was achieved, the vaccine had limited efficacy against aerosolized virus. We made a similar construct (WR100) and compared its performance with that of a recombinant vaccinia virus which had been altered in two ways (WR103) in order to improve its performance as a vaccine: a synthetic promoter was inserted upstream of the VEE coding sequence to increase the amount of VEE proteins produced, and a single nucleotide in the E2 glycoprotein gene was altered to enhance immunogenicity. The WR103 virus expressed greater amounts of VEE proteins on the surface of infected cells than did WR100, and this difference was found to correspond to a 3.5-fold increase in VEE protein production. Sera from mice immunized with WR103 contained elevated levels of antibody to VEE, and enhanced protection against subcutaneous challenge with the pathogenic Trinidad donkey strain was achieved. This altered construct could form the basis for a better vaccine against VEE.

Protection against herpes B virus infection in rabbits with a recombinant vaccinia virus expressing glycoprotein D

Herpes B virus infects naturally monkeys of the macaque genus in whom it can cause recurrent oral and genital lesions. However, when the virus infects humans it causes a neurological illness with a high case fatality rate. Successful treatment is possible but this depends on diagnosis prior to the onset of respiratory arrest, and fatalities over the last 10 years have been the result of late or no diagnostic data on which to base anti-viral intervention. An effective vaccine would be an ideal way to combat the risk of herpes B virus disease in humans working with potentially infected monkeys or their tissues. A recombinant vaccinia virus expressing herpes B virus glycoprotein D (gD) was constructed and rabbits inoculated with the chimeric virus were tested for immunoglobulin responses to herpes B virus by virus neutralisation, ELISA and Western blot analyses. Anti-gD humoral responses were detected in all vaccinated animals by ELISA and Western blot but neutralising antibody was not detected prior to challenge with herpes B virus. Non-vaccinated rabbits died within 8 days of challenge while 10/11 vaccinated animals were protected against herpes B virus disease. No antibodies to herpes B virus proteins other than gD were detectable in surviving animals, suggesting minimal herpes B virus replication post challenge. Autopsies were carried out on 4/10 rabbits which had remained healthy at 31 days post challenge and the dorsal root ganglia adjacent to the inoculation site were removed. Attempts to detect herpes B virus DNA by PCR followed by hybridisation proved negative suggesting protection against latent herpes B virus infection.

Airborne movement of anthrax spores from carcass sites in the Etosha National Park, Namibia

Tests for airborne movement of anthrax spores downwind from three heavily contaminated carcass sites were carried out under a range of wind conditions. Anthrax spores were detected in just three of 43 cyclone or gelatin filter air samples taken at distances of 6, 12 and 18 m from the sites. In addition, nine positives resulted during sampling sessions in which the site was mechanically disturbed, with a further five positives being found in sessions subsequent to those in which the site had been disturbed. The three positive samples not related to man-made disturbance were associated with the highest winds experienced during the study. Despite colony counts exceeding 100 on the culture plates in three instances, calculations showed that these represented very low worst case probable spore inhalation rates for animals or humans exposed to such levels. The low number of positives, the clear pattern of rapidly declining numbers of anthrax spores with distance downwind from the centres of the sites apparent on settle plates, and the persisting levels of contamination despite wind and rain, collectively suggest that the anthrax spores were associated with fairly heavy particles, although this was not seen by electron microscopy on soil samples from the sites. Overall, the findings are interpreted as indicating that it is very unlikely that Etosha animals contract anthrax by the inhalation route while simply in transit near or across a carcass site. The significance of the observations in relation to weather conditions in the Etosha, other studies on particulate aerosols in the region, and reports of long-distance airborne movement of microbes, is discussed.

Epidermal growth factor receptor and the adaptor protein p52Shc are specific substrates of T-cell protein tyrosine phosphatase

T-cell protein tyrosine phosphatase (TCPTP) exists as two forms generated by alternative splicing: a 48-kDa endoplasmic reticulum (ER)-associated form (TC48) and a 45-kDa nuclear form (TC45). To identify TCPTP substrates, we have generated substrate-trapping mutants, in which the invariant catalytic acid of TCPTP (D182) is mutated to alanine. The TCPTP D182A substrate-trapping mutants were transiently overexpressed in COS cells, and their ability to form complexes with tyrosine-phosphorylated (pTyr) proteins was assessed. No pTyr proteins formed complexes with wild-type TCPTP. In contrast, TC48-D182A formed a complex in the ER with pTyr epidermal growth factor receptor (EGFR). In response to EGF, TC45-D182A exited the nucleus and accumulated in the cytoplasm, where it bound pTyr proteins of approximately 50, 57, 64, and 180 kDa. Complex formation was disrupted by vanadate, highlighting the importance of the PTP active site in the interaction and supporting the characterization of these proteins as substrates. Of these TC45 substrates, the approximately 57- and 180-kDa proteins were identified as p52Shc and EGFR, respectively. We examined the effects of TC45 on EGFR signaling and observed that it did not modulate EGF-induced activation of p42Erk2. However, TC45 inhibited the EGF-induced association of p52Shc with Grb2, which was attributed to the ability of the PTP to recognize specifically p52Shc phosphorylated on Y239. These results indicate that TC45 recognizes not only selected substrates in a cellular context but also specific sites within substrates and thus may regulate discrete signaling events.

Regulation of distinct stages of skeletal muscle differentiation by mitogen-activated protein kinases

The signal transduction pathway or pathways linking extracellular signals to myogenesis are poorly defined. Upon mitogen withdrawal from C2C12 myoblasts, the mitogen-activated protein kinase (MAPK) p42Erk2 is inactivated concomitant with up-regulation of muscle-specific genes. Overexpression of MAPK phosphatase-1 (MKP-1) inhibited p42Erk2 activity and was sufficient to relieve the inhibitory effects of mitogens on muscle-specific gene expression. Later during myogenesis, endogenous expression of MKP-1 decreased. MKP-1 overexpression during differentiation prevented myotube formation despite appropriate expression of myosin heavy chain. This indicates that muscle-specific gene expression is necessary but not sufficient to commit differentiated myocytes to myotubes and suggests a function for the MAPKs during the early and late stages of skeletal muscle differentiation.

Cloning, sequencing and expression of a full-length cDNA copy of the M1 double-stranded RNA virus from the yeast, Saccharomyces cerevisiae

Strains of the budding yeast, Saccharomyces cerevisiae, may contain one or more cytoplasmic viruses with double-stranded RNA (dsRNA) genomes. The killer phenomenon in yeast, in which one cell secretes a killer toxin that is lethal to another cell, is dependent upon the presence of the L-A and M1 dsRNA viruses. The L-A viral genome encodes proteins for the viral capsid, and for synthesis and encapsidation of single-stranded RNA replication cycle intermediates. The M1 virus depends upon the L-A-encoded proteins for its capsid and for the replication of its killer-toxin-encoding genome. A full-length cDNA clone of an M genome has been made from a single dsRNA molecule and shown to encode functional killer and killer-immunity functions. The sequence of the clone indicates minor differences from previously published sequences of parts of the M1 genome and of the complete genome of S14 (an internal deletion derivative of M1) but no unreported amino acid variants and no changes in putative secondary structures of the single-stranded RNA. A 118-nucleotide contiguous segment of the M1 genome has not previously been reported; 92 of those nucleotides comprise a segment of A nucleotides in the AU-rich bubble that follows the toxin-encoding reading frame.

Postoperative nausea and vomiting. Propofol or thiopentone: does choice of induction agent affect outcome?

Postoperative nausea and vomiting (PONV) has many causes, including anaesthetic drugs. Choice of induction agent may affect the incidence of PONV, though the evidence is conflicting. We have analysed our database of outcome after surgery. Data on 4173 patients were analysed using multivariate logistic regression, with an overall incidence of PONV 21.3%. Propofol, when compared to thiopentone for induction of anaesthesia, resulted in an 18% reduction in PONV (OR = 0.82, P = 0.03). The likely postoperative benefits of propofol may outweigh concerns about its additional cost.

An assessment of the Sartorius MD8 microbiological air sampler

Tests described in this paper show that gelatine membrane filters used in the MD8 microbiological air sampling system collected monodispersed aerosols between 0.7 and 1.0 microns containing viable Bacillus subtilis var. niger spores, with an efficiency of 99.9995%. Gelatine membrane filters linked to the MD8 control pump system were as effective as the well established Casella slit-to-agar device for collecting some viable bacteria, nebulized under controlled experimental conditions and naturally occurring airborne micro-organisms in a pharmaceutical plant. By using a long flexible hose connection to the control pump, the head could be positioned where sampling was required in locations remote from the pump exhaust, making it suitable for microbiological monitoring in critical locations such as laminar flow stations and isolators.

Multiple requirements for SHPTP2 in epidermal growth factor-mediated cell cycle progression

Using transient overexpression and microinjection approaches, we examined SHPTP2's function in growth factor signaling. Overexpression of catalytically inactive SHPTP2 (PTP2CS) but not catalytically inactive SHPTP1, inhibited mitogen-activated protein (MAP) kinase activation and Elk-1 transactivation following epidermal growth factor (EGF) stimulation of 293 cells. An SHPTP2 mutant with both C-terminal tyrosyl phosphorylation sites converted to phenylalanine (PTP2YF) was also without effect; moreover, PTP2YF rescued PTP2CS-induced inhibition of EGF-induced Elk-1 transactivation. PTP2CS did not inhibit transactivation by activated Ras, suggesting that SHPTP2 acts upstream of or parallel to Ras. Neither PTP2CS nor PTP2YF inhibited platelet-derived growth factor (PDGF)-induced Elk-1 transactivation. Thus, protein-tyrosine phosphatase activity, but not tyrosyl phosphorylation of SHPTP2, is required for the immediate-early responses to EGF but not to PDGF. To determine whether SHPTP2 is required later in the cell cycle, we assessed S-phase entry in NIH 3T3 cells microinjected with anti-SHPTP2 antibodies or with a glutathione S-transferase (GST) fusion protein encoding both SH2 domains (GST-SH2). Microinjection of anti-SHPTP2 antibodies prior to stimulation inhibited EGF- but no PDGF- or serum-induced S-phase entry. Anti-SHPTP2 antibodies or GST-SH2 fusion protein could inhibit EGF-induced S-phase entry for up to 8 h after EGF addition. Although MAP kinase activation was detected shortly after EGF stimulation, no MAP kinase activation was detected around the restriction point. Therefore, SHPTP2 is absolutely required for immediate-early and late events induced by some, but not all, growth factors, and the immediate-early and late signal transduction pathways regulated by SHPTP2 are distinguishable.

Different signaling roles of SHPTP2 in insulin-induced GLUT1 expression and GLUT4 translocation

Insulin activates hexose transport via at least two mechanisms: a p21ras-dependent pathway, leading to an increase in the amount of cell surface GLUT1; and a metabolic, p21ras-independent pathway, leading to translocation of the insulin-responsive transporter GLUT4 to the cell surface. Following insulin stimulation, SHPTP2, a non-transmembrane protein-tyrosine phosphatase, associates with insulin receptor substrate 1 via its Src homology 2 (SH2) domains. Microinjection of a glutathione S-transferase fusion protein encoding the N- and C-terminal SH2 domains of SHPTP2 (GST-NC-SH2) or anti-SHPTP2 antibodies into NIH-3T3 fibroblasts overexpressing the insulin receptor blocks insulin-induced DNA synthesis. Microinjection of either GST-NC-SH2 or anti-SHPTP2 antibodies into 3T3-L1 adipocytes inhibited the insulin-stimulated increase in expression of GLUT1. In contrast, translocation of GLUT4 to the cell surface was unaffected by either GST-NC-SH2 or anti-SHPTP2 antibodies. These data confirm a role for SHPTP2 in insulin-stimulated mitogenesis and indicate that whereas SHPTP2 is necessary for insulin-stimulated expression of GLUT1, it is not required for activation of the metabolic pathway leading to GLUT4 translocation.

Protein-tyrosine-phosphatase SHPTP2 couples platelet-derived growth factor receptor beta to Ras

Protein-tyrosine-phosphatase SHPTP2 (Syp/PTP-1D/PTP2C) is the homologue of the Drosophila corkscrew (csw) gene product, which transmits positive signals from receptor tyrosine kinases. Likewise, SHPTP2 has been implicated in positive signaling from platelet-derived growth factor receptor beta (PDGFR). Upon PDGF stimulation, SHPTP2 binds to the PDGFR and becomes tyrosine-phosphorylated. We have identified tyrosine-542 (pY542TNI) as the major in vivo site of SHPTP2 tyrosine phosphorylation. The pY542TNI sequence conforms to the consensus binding site for the SH2 domain of Grb2, which, by association with Sos1, couples some growth factor receptors to Ras. Following PDGF stimulation, Grb2 binds tyrosine-phosphorylated SHPTP2. Moreover, a mutant PDGFR lacking its SHPTP2 binding site displays markedly reduced Grb2 binding. These data indicate that phosphorylation of SHPTP2 couples Grb2 to PDGFR in vivo, providing a mechanism for Ras activation by PDGFR and for positive signaling via SHPTP2 and Csw.

Calcium as a permissive factor but not an initiation factor in DNA synthesis induction in cultured rat hepatocytes by the peroxisome proliferator ciprofibrate

The non-genotoxic hepatocarcinogen and peroxisome proliferating agent, ciprofibrate, is a liver mitogen both in vivo and in cultured adult rat hepatocytes, but the mechanisms of its mitogenicity have not been elucidated. We previously observed that ciprofibrate rapidly increased hepatocyte free intracellular Ca2+ concentration ([Ca2+]i), suggesting that this effect may play a role in the initiation of DNA synthesis. In the present study, we have identified a relationship between Ca2+ and the stimulation of hepatocyte DNA synthesis by ciprofibrate. Exposure of cultured adult rat hepatocytes to ciprofibrate (200 microM) for 48 hr increased DNA synthesis by approximately 2-fold, and this response was attenuated in a Ca(2+)-deficient medium and by the Ca2+ channel blockers nicardipine and verapamil. To examine the relationship between the stimulation of hepatocyte DNA synthesis and increases in [Ca2+]i by ciprofibrate, the intracellular Ca2+ chelator 5,5'-dimethyl-1,2-bis(2-aminophenoxyethane)-N,N,N',N'-tetraacetic acid (dimethyl-BAPTA) was employed. Pretreatment of hepatocytes with dimethyl-BAPTA blocked ciprofibrate-induced [Ca2+]i increase, but did not block ciprofibrate-induced hepatocyte DNA synthesis. Dimethyl-BAPTA was only effective in reducing ciprofibrate-induced DNA synthesis when present during the latter 24 hr of a 48-hr culture period. These data suggest that the early mobilization of hepatocyte [Ca2+]i by ciprofibrate does not play an initiating role in the induction of hepatocyte DNA synthesis but rather may operate as a permissive factor for the entry of ciprofibrate-treated adult rat hepatocytes into S-phase.

Activation of the SH2-containing phosphotyrosine phosphatase SH-PTP2 by its binding site, phosphotyrosine 1009, on the human platelet-derived growth factor receptor

Much progress has been made in elucidating early events in signal transduction by growth factor receptors with intrinsic tyrosine kinase activity. Upon ligand addition, these receptors dimerize and activate, becoming phosphorylated at a number of tyrosyl residues. These phosphorylation sites serve as docking points for proteins containing src homology-2 (SH2) domains. However, little is known about how phosphotyrosine phosphatases (PTPs), participate in these events. Recently, we and others molecularly cloned a ubiquitously expressed SH2 domain-containing PTP, SH-PTP2 (Syp, PTP1D, PTP2C), and found that it interacts directly with several activated growth factor receptors via its SH2 domains. Using a peptide competition assay, we now demonstrate that the major binding site for SH-PTP2 on the platelet-derived growth factor receptor is phosphotyrosine 1009. Immunoprecipitation studies indicate that SH-PTP2 is the previously unidentified "64-kDa" protein known to bind at this site. Addition of a phosphotyrosyl peptide comprising the region around Tyr-1009 stimulates SH-PTP2 activity 5-10-fold, whereas other phosphotyrosyl peptides from the platelet-derived growth factor receptor have no stimulatory effect. Our data suggest that binding of SH-PTP2 to the activated receptor in vivo should result in stimulation of SH-PTP2 activity.

Alteration of rat liver endoplasmic reticulum Ca(2+)-ATPase thiol integrity by ciprofibrate, a peroxisome proliferator

Ciprofibrate (CP), a peroxisome proliferator, has been shown to reduce rat liver endoplasmic reticulum (ER) Ca(2+)-ATPase activity both in vitro and in vivo. The ER Ca(2+)-ATPase is highly susceptible to thiol reactivity, and maintenance of maximal enzyme activity is critically dependent upon the integrity of these thiol groups. We therefore investigated whether CP alters ER Ca(2+)-ATPase thiol groups as a possible mechanism of enzyme inhibition. Using a thiol immunoblot technique, free thiol groups specifically on the ER Ca(2+)-ATPase were localized. Exposure of freshly isolated rat liver microsomes to CP (500 microM) resulted in a loss of sulfhydryl reactivity on the ER Ca(2+)-ATPase protein at 107 kDa, as identified using the thiol immunoblot assay. However, when rat liver microsomes were exposed to CP in the presence of reduced glutathione (GSH), thiol groups on the ER Ca(2+)-ATPase were protected. Also, the reduction of ER Ca(2+)-ATPase activity by CP could be ameliorated by co-incubation of rat liver microsomes with GSH. These observations indicate that CP reduces rat liver ER Ca(2+)-ATPase activity through interactions with free thiol groups located on this enzyme.

Polymerase chain reaction for detection of herpesvirus simiae (B virus) in clinical specimens

A polymerase chain reaction (PCR) was designed which is specific to Macaca fascicularis (cynomolgus monkey) isolates of B virus. The PCR primers produced the expected 188 basepair product from the Cyno 2 strain and seven other cynomolgus monkey isolates of B virus. Oligomer hybridization with a 31-mer oligonucleotide was used to confirm the origin of this product. The PCR failed to amplify DNA of Epstein-Barr virus, cytomegalovirus, varicella-zoster virus, and other alphaherpesviruses (herpes simplex virus types 1 and 2, four SA 8 isolates and three rhesus isolates of B virus). PCR testing of swabs obtained from four orally-infected cynomolgus monkeys confirmed the presence of B virus DNA in samples previously shown to be positive by culture. In addition, PCR detected B virus in several swabs from infected monkeys that were culture negative. Total DNA extracts from the trigeminal and sacral ganglia of these animals were tested by nested PCR and B virus DNA was detected in the trigeminal ganglia of 3 of the 4 orally-infected cynomolgus monkeys. Nested PCR did not detect B virus DNA in total DNA extracts obtained from the brains of the four monkeys.

Isolation of a clone partially encoding hill kangaroo X-linked hypoxanthine phosphoribosyltransferase: sex differences in methylation in the body of the gene

An X-linked clone encoding exons 4-9 of the hypoxanthine phosphoribosyltransferase (HPRT) gene was isolated from a kangaroo (Macropus robustus: Marsupialia) lambda EMBL4 genomic library. Sequence similarity between the kangaroo and eutherian HPRT coding sequences was high; however, intron sizes varied significantly between the kangaroo and other eutherian species. HpaII and HhaI sites in the body of the gene were generally hypermethylated in vivo on the active, relative to the inactive X, with sites within intron 3 showing essentially complete correspondence of activity with methylation and inactivity with unmethylation. At approximately 5 kb downstream from the gene, a switch to unmethylation of active X-linked sites occurred. This switch occurred within a cluster of HpaII and HhaI sites that may represent a CG island associated with a subsequent gene.

Nucleotide sequence analysis of genes encoding glycoproteins D and J in simian herpes B virus

The gene encoding glycoprotein D (gD) of simian herpes B virus (SHBV) was identified by hybridization with the gD gene of herpes simplex virus type 1 (HSV-1). The gene probe bound to a 2.6 kbp SalI-EcoRI fragment of SHBV DNA, which was cloned into a plasmid vector. The nucleotide sequence of the SHBV DNA fragment was determined. Two complete and one partial open reading frames (ORFs) were found. The nucleotide sequences of the two complete ORFs are 57% and 69% identical to HSV-1 genes US5 (encoding gJ) and US6 (encoding gD), respectively. The partial ORF showed 64% similarity with HSV-1 US7 (encoding gI). The SHBV gD gene revealed many features which are also found in the gD homologues of other herpesviruses. The positions of cysteine residues and receptor-binding sites for the predicted protein are shown to be highly conserved.

Reduction of rat liver endoplasmic reticulum Ca(2+)-ATPase activity and mobilization of hepatic intracellular calcium by ciprofibrate, a peroxisome proliferator

Ciprofibrate, a peroxisome proliferating agent, induces cell proliferation in rodent liver during the early periods of exposure. Since Ca2+ plays an important role in mitogenesis, we have investigated the effects of ciprofibrate on hepatic endoplasmic reticulum (ER) Ca(2+)-ATPase, which in part regulates Ca2+ homeostasis. A single oral dose of 200 mg/kg ciprofibrate to male F344 rats produced a transient decrease in liver microsomal Ca(2+)-ATPase activity to 48% of control levels at 24 hr post-exposure. Activity had returned to control levels by 48 and 72 hr after exposure. The decrease in Ca(2+)-ATPase activity was not a function of non-specific enzymatic inhibition, since activity of another microsomal enzyme, glucose-6-phosphatase, was not altered in ciprofibrate-exposed rats. Using an ATP-driven 45Ca2+ accumulation assay, rats exposed to 25, 100 and 200 mg/kg ciprofibrate exhibited a dose-dependent inhibition of liver microsomal Ca2+ accumulation at 24 hr post-exposure. Analysis of Western immunoblots using a polyclonal antibody to the liver ER Ca(2+)-ATPase revealed a marginal increase in Ca(2+)-ATPase protein content in microsomes prepared from ciprofibrate-exposed rats compared to controls 24 hr post-exposure. These data indicate that the reduction of Ca(2+)-ATPase activity is not attributable to diminished Ca(2+)-ATPase protein content in vivo and, therefore, is due to a functional inhibition of the enzyme. Ciprofibrate also produced a concentration-dependent inhibition of rat liver ER Ca(2+)-ATPase activity in vitro (IC50 approximately 170 microM). In freshly isolated rat hepatocytes, ciprofibrate elevated the free intracellular calcium concentration ([Ca2+]i) in the presence and absence of extracellular calcium. Collectively, these results suggest that ciprofibrate mobilizes hepatic [Ca2+]i via inhibition of the ER Ca(2+)-ATPase. These events may lead to an environment of elevated [Ca2+]i during the early stages of ciprofibrate exposure and may serve to augment Ca(2+)-dependent processes, thus playing a pivotal role in the acute mitogenic response.

Lobular dissecting hepatitis in the dog

Ascites and acquired portosystemic shunts were consistent findings in six dogs with a chronic hepatitis of unusual morphology and unknown etiology. The hepatitis was characterized by a mixed inflammatory infiltrate and dissection of the lobular parenchyma by reticulin and fine collagen fibers. While limiting plates were disrupted by this process, portal inflammation was inconstant and seldom marked. Biopsy samples generally had very small, sublobular regenerative nodules, but larger nodules sometimes were present postmortem. Dilated vascular channels, representing sinusoids and portal venous radicles were a prominent feature of most affected livers. The lesions differ from previously documented chronic hepatitis in the dog, and from the chronic hepatitides in man.