Multiple antigenic peptides facilitate generation of anti-prion antibodies

Recent reports have demonstrated the ability of anti-prion antibodies to inhibit PrPSc propagation. Due to the relatively poor immunogenic properties of both PrPC and PrPSc, the generation of anti-prion antibodies still causes a significant problem in the development of immunotherapeutic strategies. This study examines the potential of multiple antigenic peptides (MAPs) to raise an antibody response to prion derived sequences in mice. The MAP was constructed of a four spiked ring. Two spikes containing human or mouse derived prion amino acid sequences and two spikes containing the universally promiscuous tetanus toxoid sequence (aa 830-844) which was used to assist T-cell-dependent B-cell antibody production. Following vaccinations with the MAP or MAP plus adjuvant, sera were taken and antibody titres assessed. The MAP containing only the mouse sequence failed to elicit a significant antibody response. MAPs containing human prion sequences elicited antibody production to the corresponding prion sequence. Further analysis also demonstrated that these peptides were able to generate antibody responses that recognize conserved human and mouse sequences. These homologous sequences contain the heralded PrPSc specific sequence 'Tyr-Tyr-Arg' and therefore these MAPs may have some therapeutic potential.

Inhalation anaesthesia for castration of newborn piglets: experiences with isoflurane and isoflurane/NO

The aim of this study was to evaluate the inhalation anaesthesia with isoflurane and isoflurane/N2O by mask induction for routine castration of piglets under 14 days of age.

MATERIAL AND METHODS

Eighty-five male piglets aged between 4 and 12 days were used in a matched pair test. Two piglets of the same litter with the same weight were selected. One was castrated with, the other without anaesthesia. Induction was performed with either isoflurane (group ISO) or isoflurane/nitrous oxide (group ISO/N2O) in oxygen through a modified bain-breathing system. Induction time was 90 and 60 s for group ISO and group ISO/N2O, respectively. The disappearance of the palpebral reflex was recorded. The reaction of the piglets during castration was judged according to a scoring system separately for both testicles during skin incision and dissection of the spermatic cord. The scores were added and mean values were calculated. Total anaesthesia time, castration time and quality of recovery was recorded. Blood was collected from all piglets immediately after castration for measurement of ACTH and beta-endorphin values. Statistical analysis were performed by the Kruskal-Wallis test for nonparametric data and one-way anova (NCSS 2000, Kaysville, UT, USA).

RESULTS

Induction of anaesthesia proved to be smooth in all cases. The palpebral reflex disappeared after 36.5 s in group ISO/N2O versus 51 s in group ISO. Mean castration scores were 0.6 in group ISO and 0 in group ISO/N2O, whereas 7.7 in piglets with no anaesthesia. These scores were significantly different. Mean anaesthesia time was 128 s (30-390) for group ISO and 123 s (70-220) for group ISO/N2O. No deaths occurred. The differences in the levels of ACTH and beta-endorphins in the blood plasma in the different groups showed no statistical difference.

DISCUSSION

This study demonstrates that isoflurane or isoflurane/N2O anaesthesia by mask induction proves to be a safe, short and reliable method in piglets undergoing castration. Reaction to the castration procedure were significantly reduced. Stress hormone values were not different between the groups because of a large individual difference.

Cell mediated immune responses against human prion protein

Vaccination approaches that may provide protection against the abnormal form of prion protein (PrPSc) have recently focused on the ability of antibodies to prevent PrPSc propagation. Progress has been hampered due to the difficulty in generating antibody responses in wild type mice, which is believed to be a consequence of T cell tolerance to the normal form of prion protein (PrPC). The problem of tolerance can be avoided using transgenic mice unable to express PrPC. This study examines active PrP specific T cell responses that can be produced in PrP null (PrP 0/0) mice using simple peptide vaccination procedures. Spleenocytes recovered from vaccinated PrP 0/0 mice were tested in vitro for their specificity with T cell recognition demonstrated through a proliferative response to the peptide. Analysis of mRNA also indicates the stimulation of a heterogenous population of T cells with an increase in cytokines and cytotoxicity associated mRNA. Responsive T cells were expanded using a T cell cloning procedure and demonstrated an ability to recognize the mature human prion protein. These clones may potentially be used to negate the problem of T cell tolerance in wild type mice.

Immunogenicity of a recombinant human immunodeficiency virus (HIV)-canarypox vaccine in HIV-seronegative Ugandan volunteers: results of the HIV Network for Prevention Trials 007 Vaccine Study

In the first preventative human immunodeficiency virus (HIV) vaccine study to be carried out in Africa, 40 HIV-seronegative Ugandan volunteers were randomly assigned to receive a canarypox vector containing HIV-1 clade B (env and gag-pro) antigens (ALVAC-HIV; n = 20), control vector containing the rabies virus glycoprotein G gene (n = 10), or saline placebo (n = 10). Cytotoxic T lymphocyte activity against target cells expressing clade A, B, and D antigens was assessed using standard chromium-release and confirmatory interferon-gamma enzyme-linked immunospot (ELISPOT) assays. Neutralizing antibody responses to cell line-adapted strains and primary isolates in all 3 clades were also tested. Twenty percent of vaccine recipients generated detectable cytolytic responses to either Gag or Env, and 45% had vaccine-induced HIV-specific CD8(+) T cell responses, as measured by the ELISPOT assay. In contrast, only 5% of the control group had vaccine-specific responses. Neutralizing antibodies against primary and laboratory-adapted HIV-1 clade B strains were seen in 10% and 15% of vaccine recipients, respectively, but responses against clades A and D were not detected. Although the immunogenicity of this clade B-based vaccine was low, ALVAC-HIV elicited CD8(+) T cell responses with detectable cross-activity against clade A and D antigens in a significant proportion of vaccine recipients.

Cellular immune responses against hepatitis C virus: the evidence base 2002

Hepatitis C virus (HCV) is an RNA virus which is estimated to persistently infect about 170 million people worldwide. After acute infection, there is an initial period during which long-term outcome is decided. There is strong evidence that the cellular immune responses, involving both CD4+ and CD8+ T lymphocytes, are involved at this stage and it is their effectiveness which determines outcome. What is not understood is what determines their effectiveness. The most important component of this is likely to be some aspect of epitope selection, itself dictated by host MHC. Thus, to understand host immunity to HCV, we need to have a detailed understanding of the peptides involved in T lymphocyte responses. In this review, we discuss the peptide epitopes that have been identified so far, and their potential significance. We relate this to a scheme of host defence which may be useful for understanding natural and vaccine-induced immunity.

Detection of cis-trans isomers of a synthetic peptide fragment of erythropoietin

The synthesis of the protected fragment t-butoxycarbonyl-alanine-isoleucine-serine(benzyl)-proline (Pro)-Pro-OH derived from the hormone erythropoietin is described. The analysis of the peptide by high-pressure liquid chromatography (HPLC) and thin-layer chromatography (TLC) yields apparently inconsistent results. Although HPLC consistently indicates the presence of only one component, TLC reveals a number of distinct species. Because satisfactory amino acid analysis and fast atom bombardment-mass spectrometry results are obtained, we think it possible that the distinct components arise from the cis-trans isomerization of the peptide bonds to the prolyl residues. An analysis using capillary electrophoresis under basic conditions identifies four components in the final product. Also, under similar conditions proton nuclear magnetic resonance spectroscopy is able to confirm the presence of cis and trans isomers. The results from this study demonstrate the usefulness of each of the four techniques in identifying the isomerism of the standard amino acid-Pro bond with respect to the peptide's ionic state.

Specific proliferative T cell responses and antibodies elicited by vaccination with simian immunodeficiency virus Nef do not confer protection against virus challenge

The efficacy of immunizing with a combination of simian immunodeficiency virus (SIV) Nef vaccines was evaluated. Four vaccinates received three intradermal immunizations with recombinant vaccinia virus that expressed SIV Nef, followed by three intramuscular immunizations with rDNA also expressing SIV Nef. Finally, the four vaccinates received two subcutaneous boosts with recombinant SIV Nef protein. This immunization protocol elicited anti-Nef antibodies in all of the vaccinates as well as specific proliferative responses. However, specific cytotoxic T cell responses were not detected before virus challenge. All vaccinates were challenged intravenously with 10 MID(50) of SIVmacJ5 along with four controls. All eight subjects became infected after SIV challenge and there were no group-specific differences in virus load as measured by virus titration and vRNA analysis. The results of this study support indirectly the report from Gallimore and colleagues (Nat Med 1995;1:1667) suggesting that CD8(+) T lymphocyte responses are required for Nef-based vaccines to restrict SIV infection. If Nef-based vaccines are to be beneficial in controlling infection with immunodeficiency viruses, then it will be necessary to develop more effective immunization protocols that elicit potent CD8(+) cell responses reproducibly.

Catastrophic shifts in ecosystems

All ecosystems are exposed to gradual changes in climate, nutrient loading, habitat fragmentation or biotic exploitation. Nature is usually assumed to respond to gradual change in a smooth way. However, studies on lakes, coral reefs, oceans, forests and arid lands have shown that smooth change can be interrupted by sudden drastic switches to a contrasting state. Although diverse events can trigger such shifts, recent studies show that a loss of resilience usually paves the way for a switch to an alternative state. This suggests that strategies for sustainable management of such ecosystems should focus on maintaining resilience.

Sustained dysfunction of antiviral CD8+ T lymphocytes after infection with hepatitis C virus

Hepatitis C virus (HCV) sets up persistent infection in the majority of those exposed. It is likely that, as with other persistent viral infections, the efficacy of T-lymphocyte responses influences long-term outcome. However, little is known about the functional capacity of HCV-specific T-lymphocyte responses induced after acute infection. We investigated this by using major histocompatibility complex class I-peptide tetrameric complexes (tetramers), which allow direct detection of specific CD8+ T lymphocytes ex vivo, independently of function. Here we show that, early after infection, virus-specific CD8+ T lymphocytes detected with a panel of four such tetramers are abnormal in terms of their synthesis of antiviral cytokines and lytic activity. Furthermore, this phenotype is commonly maintained long term, since large sustained populations of HCV-specific CD8+ T lymphocytes were identified, which consistently had very poor antiviral cytokine responses as measured in vitro. Overall, HCV-specific CD8+ T lymphocytes show reduced synthesis of tumor necrosis factor alpha (TNF-alpha) and gamma interferon (IFN-gamma) after stimulation with either mitogens or peptides, compared to responses to Epstein-Barr virus and/or cytomegalovirus. This behavior of antiviral CD8+ T lymphocytes induced after HCV infection may contribute to viral persistence through failure to effectively suppress viral replication.

Importance of the P4' residue in human granzyme B inhibitors and substrates revealed by scanning mutagenesis of the proteinase inhibitor 9 reactive center loop

The cytotoxic lymphocyte serine proteinase granzyme B induces apoptosis of abnormal cells by cleaving intracellular proteins at sites similar to those cleaved by caspases. Understanding the substrate specificity of granzyme B will help to identify natural targets and develop better inhibitors or substrates. Here we have used the interaction of human granzyme B with a cognate serpin, proteinase inhibitor 9 (PI-9), to examine its substrate sequence requirements. Cleavage and sequencing experiments demonstrated that Glu(340) is the P1 residue in the PI-9 RCL, consistent with the preference of granzyme B for acidic P1 residues. Ala-scanning mutagenesis demonstrated that the P4-P4' region of the PI-9 RCL is important for interaction with granzyme B, and that the P4' residue (Glu(344)) is required for efficient serpin-proteinase binding. Peptide substrates based on the P4-P4' PI-9 RCL sequence and containing either P1 Glu or P1 Asp were cleaved by granzyme B (k(cat)/K(m) 9.5 x 10(3) and 1.2 x 10(5) s(-1) M(-1), respectively) but were not recognized by caspases. A substrate containing P1 Asp but lacking P4' Glu was cleaved less efficiently (k(cat)/K(m) 5.3 x 10(4) s(-1) M(-1)). An idealized substrate comprising the previously described optimal P4-P1 sequence (Ile-Glu-Pro-Asp) fused to the PI-9 P1'-P4' sequence was efficiently cleaved by granzyme B (k(cat)/K(m) 7.5 x 10(5) s(-1) M(-1)) and was also recognized by caspases. This contrasts with the literature value for a tetrapeptide comprising the same P4-P1 sequence (k(cat)/K(m) 6.7 x 10(4) s(-1) M(-1)) and confirms that P' residues promote efficient interaction of granzyme B with substrates. Finally, molecular modeling predicted that PI-9 Glu(344) forms a salt bridge with Lys(27) of granzyme B, and we showed that a K27A mutant of granzyme B binds less efficiently to PI-9 and to substrates containing a P4' Glu. We conclude that granzyme B requires an extended substrate sequence for specific and efficient binding and propose that an acidic P4' substrate residue allows discrimination between early (high affinity) and late (lower affinity) targets during the induction of apoptosis.

Environmental health and antisocial behavior: implications for public policy

Antisocial behavior persists as a preeminent public policy issue in the United States. A more critical assessment of both the policies and the programs designed to address this problem is necessary, and new risk factors for antisocial behavior need to be investigated. Sufficient evidence exists to hypothesize that exposure to neurotoxins may be a risk factor for antisocial behavior. Neurotoxins such as lead have been demonstrated to affect the cognitive development of children, and impaired cognition is accepted as a risk factor for antisocial behavior. Little consideration has been given, however, to the possible link between neurotoxins and human behavior. This paper presents a biologically and socially plausible justification for this association, reviews the supporting evidence, and emphasizes the need for additional investigation of the phenomenon. Elucidation of this risk factor may lead to new strategies for preventing or mitigating antisocial behaviors among youth and adults.

Local regulation of glucocorticoid activity in sites of inflammation. Insights from the study of tuberculosis

In sites of inflammation there is a change in the equilibrium between the enzymes that inactivate cortisol by conversion to cortisone and those that reactivate cortisone by conversion to cortisol. Current evidence suggests that during an immune response with a Type 1 cytokine profile such as tuberculosis, there is locally enhanced reductase activity with locally increased cortisol concentrations due to recruitment of cortisone. This results in enhanced cortisol mediated feedback on the inflammatory process, and deviation of the response towards Type 2. Preliminary data suggest that eventually, in the presence of Type 2 cytokine polarization, the enzyme equilibrium may reverse again and cortisol is then locally inactivated to cortisone. Together with changes in glucocorticoid receptor expression and function this may result in local cortisol resistance and susceptibility to tissue damage mediated by proinflammatory cytokines. These observations help to explain the sequence of events in several infectious, inflammatory and autoimmune diseases.

Synthesis and kinetic evaluation of peptide alpha-keto-beta-aldehyde-based inhibitors of trypsin-like serine proteases

New, synthetic peptide analogues bearing a C-terminal basic alpha-keto-beta-aldehyde moiety were prepared as novel inhibitors of the trypsin-like serine proteases. The compounds, Ac-Leu-Leu-Arg-COCHO, Ac-Arg-Gln-Arg-COCHO and Boc-Val-Leu-Lys-COCHO were evaluated kinetically against trypsin and three other trypsin-like serine proteases, tryptase, plasmin and thrombin, all of which are implicated as mediators of important disease processes. Results illustrate that alpha-keto-beta-aldehydes are potent inhibitors, with similar potency to comparable peptide aldehydes, and intriguingly, appearto act, in some instances, by a novel mechanism of action. Ac-Leu-Leu-Arg-COCHO, an analogue of the natural product leupeptin, is a potent, tight-binding inhibitor of trypsin (Ki(final) = 1.9 microM), plasmin (Ki(final) = 4.9 microM) and tryptase (Ki(final) = 1.2 microM) and an irreversible inactivator of thrombin (k2nd 4,500 M(-1).min(-1)). Boc-Val-Leu-Lys-COCHO was found to be a tight-binding inhibitor of its target protease plasmin (Ki(final) = 3.1 microM) and was inactive against thrombin. Ac-Arg-Gln-Arg-COCHO was a slow-binding inhibitor of tryptase (Ki(final) = 1.6 microM) and also irreversibly inactivated trypsin (k2nd = 8,920 M(-1) min(-1)). Peptides or peptidomimetics with a C-terminal basic alpha-keto-beta-aldehyde function thus provide a useful new molecular template for the development of new therapeutic agents against a wide range of disorders, such as coagulopathies and asthma, which may be mediated by the aberrant activity of trypsin-like serine proteases.

Strategies for the inhibition of serine proteases

Serine proteases have been shown to play a multifarious role in health and disease. As a result, there has been considerable interest in the design and development of synthetic inhibitors of these enzymes. In view of their diverse roles in biological processing events, one of the great challenges in such endeavours has been the need to produce compounds with exquisite selectivity. Inhibitor design has been broadly guided by the use of either peptide- or heterocyclic-based compounds, designed to exploit the known substrate specificity characteristics of individual enzymes. This review describes the thinking and strategies employed in such efforts.

A study of the anti-invasive properties of N-alpha-phthalimidomethyl-ketomethylene tripeptide-based metalloprotease inhibitors

We have developed matrix metalloprotease (MMP) inhibitors based on synthetic peptides incorporating a non-cleavable peptide-bond isostere at the site of the putative scissile bond. These inhibitors, N-alpha-phthaloyl-Gly-psi(CO-CH2)-Leu-Tyr-Ala-NH2 (Pht-G-CH2-LYA-NH2) and N-alpha-phthaloyl-Gly-psi(CO-CH2)-Leu-Tic-Ala-NH2 (Pht-G-CH2-LTcA-NH2) were kinetically evaluated against the type IV collagenases, gelatinase A (MMP-2) and B (MMP-9), and compared with an exactly analogous chelating-based inhibitor, N-alpha-mercaptoacetyl-Leu-Tyr-Ala-NH2 (HSCH2CO-LYA-NH2). The peptide inhibitors were also tested for their anti-invasive effects on breast carcinoma cell lines using a modification of the Boyden chamber assay. Gelatin zymography was utilized to identify gelatinolytic activities present in media removed from cultured breast cancer cells. Of the two N-alpha-phthalimidomethyl-ketomethylene peptide-based inhibitors, Pht-G-CH2-LYA-NH2 proved the more effective inhibitor of MMP-2 and MMP-9 (Ki 34.27 and 45.75 microM, respectively). However, when tested against two breast cancer cell lines, T47D and MDA-MB-231, both inhibitors were able to effectively reduce tumour cell invasion through a type IV collagen matrix by up to 91.2%. Of particular interest was the observation that Pht-G-CH2-LYA-NH2 was the most potent inhibitor of invasion by the highly aggressive MDA-MB-231 cells, despite the cells' relative lack of active secreted metalloprotease activity. The results obtained from this kinetic and anti-invasive analysis of the new inhibitors suggest that compounds incorporating the N-alpha-phthalimidomethyl-ketomethylene peptide-bond isostere may have potential for development as new agents with anti-metastatic properties.

Observers' reaction to parent-child intimacy

A study was carried out to examine how people react to acts of intimacy between parent and child. Based on an extensive series of studies reported in 1998 by Reis who found less intimate interactions between two men who are friends than between men or women or between two women who are friends, it was reasoned that intimacy between two males may violate norms of our culture, so it was predicted that people would react less favorably to intimacy between father and son than to intimacy between father and daughter, mother and daughter, or mother and son. Men (n = 19) and women (n=26), most of whom were 18-24 years of age, read versions of a mother or father having an intimate interaction (lap-sit, hair-stroke, hug/kiss) with an 11-yr.-old daughter or son and then rated the act on a 7-point scale from good to bad. As predicted, the undergraduates rated intimate interactions between father and son less favorably than those between father and daughter, mother and daughter, and mother and son.

Evaluation of a model of intervention to create a visually enriched environment

Within a day resource for people with learning disabilities 'stand-alone' signing training proved ineffectual to sustain lasting change in the formalised gestural behaviours of carers. Consideration was given to setting conditions pre- and post-training and a new model of delivery evolved, designed in partnership with day resource staff. Aims of intervention were to promote the adoption and active use of signing as an aid to communication and move towards a partnership framework which values the role of carers as co-facilitators and lessens dependency on the therapist. This paper describes and evaluates a training model which was found to be successful in translating knowledge into changes in practice and discusses the critical factors which should be built into future interventions.

System dynamics and action research in aged care

This paper documents an Action Research project undertaken to implement a Continuity of Care Model in anExtended Care Centre. System Dynamics modelling and group-modelling techniques were used to examine andimprove patient length of stay (LOS). Several indicators of success of the project are noted. They included thereduction of LOS, improvements in teamwork and staff morale, and various systemic adaptations in other parts ofthe health care sector. Upstream providers responded to the reductions in patient numbers by swamping the Centrewith intractable patients. This effectively reduced up-stream providers' LOS, and returned the Centre's LOS to pre-interventionlevels.

Inhibition of Escherichia coli glucosamine synthetase by novel electrophilic analogues of glutamine--comparison with 6-diazo-5-oxo-norleucine

A series of electrophilic glutamine analogues based on 6-diazo-5-oxo-norleucine has been prepared, using novel synthetic routes, and evaluated as inhibitors of Escherichia coli glucosamine synthetase. The gamma-dimethylsulphonium salt analogue of glutamine was found to be one of the most potent inactivators of this enzyme yet reported, with an apparent second order rate constant (k2/Ki) of 3.5 x 10(5) M(-1) min(-1).