Santalbic acid from quandong kernels and oil fed to rats affects kidney and liver P450

Kernels of the plant Santalum acuminatum (quandong) are eaten as Australian 'bush foods'. They are rich in oil and contain relatively large amounts of the acetylenic fatty acid, santalbic acid (trans-11-octadecen-9-ynoic acid), whose chemical structure is unlike that of normal dietary fatty acids. When rats were fed high fat diets in which oil from quandong kernels supplied 50% of dietary energy, the proportion of santalbic acid absorbed was more than 90%. Feeding quandong oil elevated not only total hepatic cytochrome P450 but also the cytochrome P450 4A subgroup of enzymes as shown by a specific immunoblotting technique. A purified methyl santalbate preparation isolated from quandong oil was fed to rats at 9% of dietary energy for 4 days and this also elevated cytochrome P450 4A in both kidney and liver microsomes in comparison with methyl esters from canola oil. Santalbic acid appears to be metabolized differently from the usual dietary fatty acids and the consumption of oil from quandong kernels may cause perturbations in normal fatty acid biochemistry.

A “universal” human influenza A vaccine

We have previously reported on a universal human influenza A vaccine, based on the external domain of the transmembrane viral M2-protein (M2e) [Nature Medicine 5 (1999) 1119]. M2-protein is scarcely present on the virus but is abundantly expressed on virus-infected cells. The external domain, M2e, is 23-amino acids long and as such weakly immunogenic. But when presented on an appropriate carrier, such as hepatitis B virus core (HBc) particles, it induces a high titer antibody response that in mice effectively protects against a potentially lethal influenza infection. The advantage of M2e as an antigen is the conservation of its sequence that has hardly changed since the first influenza virus was isolated in 1933, despite numerous epidemics and several pandemics. Various constructs, e.g. M2e fused at the N-terminus of the HBc subunit or inserted in the immuno-dominant loop, were evaluated as a vaccine. They conferred full protection when administered together with an adjuvant. Several adjuvants were tested in conjunction with intraperitoneal vaccine administration, while the non-toxic enterotoxin mutant LT(R192G) was used for intranasal vaccination. Appropriate combinations of vaccine construct and adjuvant allowed to obtain anti-M2e IgG2a serum titers above 10,000, and this provided complete protection.

A system for logging incontinence events using a simple disposable sensor

Many elderly people entering residential or nursing care are already incontinent to some degree, relying on incontinence pads to deal with the consequences. A proportion of these people have been shown to exhibit a regular pattern in their incontinence, which opens up the possibility of mitigating the problem by instituting an individual toileting regime for the person. This can reduce their reliance on incontinence pads, both improving their quality of life, and reducing the cost of care. This paper covers the development and evaluation of a sensor for detecting incontinence events, suitable for use in this setting, and describes the design of an associated electronic logger. The devices form part of an assessment system intended to identify a pattern in incontinence where it exists, and to help with the design of the toilet regime for an individual. The requirement is that the system must reliably record incontinence events, and present the information describing them in a manner appropriate to the users of the devices, who are likely to be non-technical and non-specialist.

A modified hepatitis B virus core particle containing multiple epitopes of the Plasmodium falciparum circumsporozoite protein provides a highly immunogenic malaria vaccine in preclinical analyses in rodent and primate hosts

Despite extensive public health efforts, there are presently 200 to 400 million malaria infections and 1 to 2 million deaths each year due to the Plasmodium parasite. A prime target for malaria vaccine development is the circumsporozoite (CS) protein, which is expressed on the extracellular sporozoite and the intracellular hepatic stages of the parasite. Previous studies in rodent malaria models have shown that CS repeat B-cell epitopes expressed in a recombinant hepatitis B virus core (HBc) protein can elicit protective immunity. To design a vaccine for human use, a series of recombinant HBc proteins containing epitopes of Plasmodium falciparum CS protein were assayed for immunogenicity in mice [A. Birkett, B. Thornton, D. Milich, G. A. Oliveira, A. Siddique, R. Nussenzweig, J. M. Calvo-Calle, and E. H. Nardin, abstract from the 50th Annual Meeting of the American Society of Tropical Medicine and Hygiene 2001, Am. J. Trop. Med. Hyg. 65(Suppl. 3):258, 2001; D. R. Milich, J. Hughes, J. Jones, M. Sallberg, and T. R. Phillips, Vaccine 20:771-788, 2001]. The present paper summarizes preclinical analyses of the optimal P. falciparum HBc vaccine candidate, termed ICC-1132, which contains T- and B-cell epitopes from the repeat region and a universal T-cell epitope from the C terminus of the CS protein. The vaccine was highly immunogenic in mice and in Macaca fascicularis (cynomolgus) monkeys. When formulated in adjuvants suitable for human use, the vaccine elicited antisporozoite antibody titers that were logs higher than those obtained in previous studies. Human malaria-specific CD4(+)-T-cell clones and T cells of ICC-1132-immunized mice specifically recognized malaria T-cell epitopes contained in the vaccine. In addition to inducing strong malaria-specific immune responses in naïve hosts, ICC-1132 elicited potent anamnestic antibody responses in mice primed with P. falciparum sporozoites, suggesting potential efficacy in enhancing the sporozoite-primed immune responses of individuals living in areas where malaria is endemic.

Limited humoral immunity in hepatitis C virus infection

BACKGROUND & AIMS

The extremely high rate of chronicity to hepatitis C virus (HVC) infection suggests an inefficient immune response. The humoral immune response to HCV was evaluated in 60 patients with chronic HCV infection and in 12 patients acutely infected with HCV.

METHODS

A number of recombinant HCV antigens including the core, envelope 2 (E2), nonstructural (NS) 3, NS4, and NS5 proteins, and NS4a and E2-HVR-1 peptides were used in enzyme-linked immunoassays.

RESULTS

Immunoglobulin (Ig) G antibody responses to these viral antigens, except for the HCV core, were highly restricted to the IgG1 isotype. The prevalence of antibodies of the IgG1 isotype specific for the HCV core, E2, E2-HVR1, NS3 (helicase domain), NS4, and NS5 antigens was 97%, 98%, 28%, 88%, 33%, and 68%, respectively. Antibodies of the IgG3 isotype specific for E2, E2-HVR-1, NS3, NS4, and NS5 were detected in a minority of serum samples. The IgG2 and IgG4 isotypes were rarely if ever detected. Furthermore, antibody responses to HCV viral antigens were of relatively low titer and, with the exception of anti-HCV core, were delayed in appearance until the chronic phase of infection.

CONCLUSIONS

The IgG1 restriction, low titer, and delayed appearance of antibody responses elicited during HCV infection suggest that the immunogenicity of HCV proteins is limited in the context of natural infection. Inasmuch as recombinant HCV viral antigens perform as relatively normal immunogens in small animals, we suggest that the defective humoral immune responses during HCV infection may be attributable to an "immune avoidance" strategy.

Human and murine antibody recognition is focused on the ATPase/helicase, but not the protease domain of the hepatitis C virus nonstructural 3 protein

The hepatitis C virus (HCV) nonstructural (NS) 3 protein has been shown to possess at least two enzymatic domains. The amino terminal third contains a serine-protease domain, whereas the carboxy terminal two thirds is comprised of an adenosine triphosphatase (ATPase)/helicase domain. These domains are essential for the maturation of the carboxy-terminal portion of the HCV polyprotein and catalyze the cap synthesis of the RNA genome. In this report, human and murine antibody responses induced by NS3 were characterized using a recombinant full-length NS3 (NS3-FL) protein, or the isolated protease or ATPase/ helicase domains, expressed and purified from Escherichia coli. Sera from 40 patients with chronic HCV infection were assayed in enzyme-linked immunoassays (EIAs) for antibody binding to the panel of NS3 proteins. Virtually all patient sera contained antibodies specific for NS3-FL and the ATPase/helicase domain, whereas only 10% of sera reacted with the protease domain of NS3. Human antibodies reactive with NS3-FL were highly restricted to the immunoglobulin G1 (IgG1) isotype and were inhibited by soluble ATPase/helicase, but not by the protease domain. The anti-NS3 (ATPase/helicase) reactivity decreased on denaturation by sodium dodecyl sulfate (SDS) and beta-mercaptoethanol (2ME), suggesting the recognition of nonlinear or conformational B-cell determinants. Similar to infected humans, mice immunized with NS3-FL developed high-titered primary antibody responses to the NS3 ATPase/ helicase domain, whereas an anti-NS3 protease response was not observed after primary or secondary immunizations. Thus, the human and murine humoral immune responses to the HCV NS3 protein are focused on the ATPase/helicase domain, are restricted to the IgG1 isotype in humans, and are conformationally dependent. Unexpectedly, in both species, the NS3 protease domain, present in the context of the full-length NS3, appears to possess low intrinsic immunogenicity in terms of antibody production.

Immune responses to the hepatitis C virus NS4A protein are profoundly influenced by the combination of the viral genotype and the host major histocompatibility complex

The interaction between the host major histocompatibility complex (MHC) and the genotype of the hepatitis C virus (HCV) was analysed using synthetic full-length non-structural (NS) 4A proteins, residues 1658-1712, of genotypes 1b, 2b, 3a, 4a and 5a. Human and murine antibodies specific for the five NS4A genotypes analysed focused on residues 1688-1707. In immunized B10 H-2 congenic mice, the H-2d, H-2f and H-2s haplotypes were good responders to NS4A, irrespective of the viral genotype. In contrast, the H-2k haplotype was a low or non-responder to all NS4A genotypes, except for genotype 2b. Also, H-2f- and H-2s-restricted NS4A genotype 1b-specific T-cells focused on residues 1670-1679 and 1683-1692, respectively, whereas H-2k-restricted NS4A genotype 2b-specific T-cells focused on the carboxy terminus. Interestingly, H-2f-restricted genotype 1b-specific T-cells did not cross-react with T-cell site analogues of seven other genotypes, whereas the H-2s-restricted, genotype 1b-specific T-cells cross-reacted with genotypes 1a, 4a and 5a. Thus the combination of viral genotype and host MHC profoundly influences the ability to mount an HCV NS4A-specific immune response.

Interferon-alpha treatment induces delayed CD4 proliferative responses to the hepatitis C virus nonstructural protein 3 regardless of the outcome of therapy

The proliferative responses to a hepatitis C virus (HCV) recombinant nonstructural protein 3 (rNS3) were analyzed in 9 patients with chronic HCV infection before, during, and after 24 weeks of treatment with interferon-alpha (IFN-alpha) alone or in combination with ribavirin. Regardless of the therapy and the subsequent outcome, all patients showed an increased rNS3-specific proliferative response in peripheral blood mononuclear cells in vitro within 48 weeks from the start of therapy (P < .01). The proliferating cell phenotype was CD4 and was dependent on HLA-DP/DQ/DR class II antigen presentation. rNS3 induced in vitro detectable interleukin (IL)-2, IL-10, and IFN-gamma production in some patients before or after therapy (or both). No significant differences existed between responders and relapsed responders plus nonresponders with respect to the NS3-specific CD4 T helper (Th) cell responses. Thus, IFN-alpha therapy induces HCV NS3-specific CD4 Th cell proliferation regardless of the outcome of therapy.

Antibody production against hepatitis C virus core and nonstructural 3 proteins is highly sensitive to deficits in T-cell function

The influence of suppression of CD4+ and CD8+ T cells on the humoral responses to hepatitis C virus (HCV) core and nonstructural 3 proteins was studied. An increasing viral burden cannot substitute for the lack of functional T cells in maintaining humoral HCV-specific responses.

Immunogenicity and antigenicity of the ATPase/helicase domain of the hepatitis C virus non-structural 3 protein

The immunogenicity and antigenicity of an enzymatically functional (ATPase/helicase) recombinant protein encompassing residues 1207-1612 of the hepatitis C virus (HCV) non-structural 3 (NS3) protein was characterized using B10 congenic mice. Previous studies have indicated a high frequency of NS3-specific antibodies in HCV-infected humans. Similarly, all six immunized murine haplotypes were antibody responders to the NS3 ATPase/helicase domain, with the H-2k and H-2s haplotypes as high responders. As also observed in HCV-infected humans, the murine NS3 antibodies were predominantly directed to conformational determinants. Irrespective of the murine haplotype, IgG1 predominated in the primary anti-NS3 response, whereas IgG1 and IgG2b predominated in the secondary response. The antibody responder hierarchy was reiterated at the T cell level, with the H-2k and the H-2s haplotypes as the best responders. In both the H-2d and H-2k haplotypes ATPase/helicase-primed T cells secreted interleukin 2 and interferon gamma, corroborating observations from HCV-infected humans. In the H-2d, H-2k and H-2s haplotypes the fine specificity of the T cell recognition of the ATPase/helicase domain was further characterized. Multiple, although generally weak, T cell recognition sites were found for all three haplotypes. The large size of the NS3 protein together with the presence of multiple class II binding motifs explain the high prevalence of NS3 antibodies in immunized mice and predict a similar explanation for the observed high frequency of NS3-specific antibodies in HCV-infected humans.

Resistant starch lowers fecal concentrations of ammonia and phenols in humans

We investigated the effect of resistant starch (RS) on markers of colonic protein metabolism. Eleven subjects participated in a randomized crossover study in which they consumed either high-RS (39 +/- 3 g/d, -chi +/- SEM) or low-RS (5 +/- 0.4 g/d) diets for 3 wk. All other macronutrients were kept constant. During the high-RS diet daily excretion of fecal nitrogen increased from 1.84 +/- 0.15 to 2.86 +/- 0.42 g/d (P < 0.01) and excretion of fecal phenols fell from 9.2 +/- 1.4 to 5.3 +/- 0.8 mg/d (P < 0.01). Fecal concentrations of ammonia decreased from 397 +/- 33 to 278 +/- 49 microgram/g (P < 0.01) and phenols decreased from 69 +/- 8 to 39 +/- 10 microgram/g (P < 0.001). Daily output of urinary ammonia, urea, phenols, and total nitrogen did not change significantly, but pH decreased from 6.4 +/- 0.1 to 6.2 +/- 0.1 (P < 0.05) during the high-RS period. These results suggest that RS significantly attenuates the accumulation of potentially harmful byproducts of protein fermentation in the human colon.

Use of alpha-N,N-bis[carboxymethyl]lysine-modified peroxidase in immunoassays

Horseradish peroxidase was activated by periodate oxidation of the carbohydrate moiety and then modified by the covalent attachment of alpha-N,N-bis[carboxyethyl]lysine (CM-Lys) by reductive alkylation using sodium cyanoborohydride. The resultant CM-Lys peroxidase was charged with nickel ions and then used as a specific labeling reagent for histidine-tagged recombinant proteins. This labeling method was effective for proteins that are soluble or insoluble in the absence of chaotropic agents. The labeled proteins were very effective in direct sandwich enzyme-linked immunosorbent assay for detecting antibodies against the protein in sera as demonstrated by assays for antibodies to such diverse viral proteins as hepatitis B surface and core proteins, hepatitis C core and helicase protein (NS3), and retroviral core proteins.

Effect of resistant starch on fecal bulk and fermentation-dependent events in humans

This study investigated the effect of two diets, which differed in resistant starch (RS) concentration, on fecal bulk and fermentation-dependent events in 11 humans. Amounts of RS consumed were 5.0 +/- 0.4 and 39.0 +/- 3.0 g/d (mean +/- SEM) for the low- and high-RS diets, respectively. The two diets were fed for 3 wk each in a randomized crossover design. Fecal collections were made in the third week of each study period. The high-RS diet produced an increase (P < 0.01) in total fecal output (from 138 +/- 22 to 197 +/- 37 g/d) and lowered fecal pH (6.9 +/- 0.1 to 6.3 +/- 0.1). There were significant increases (P < 0.05) in the fecal concentrations and daily excretion of butyrate (+38% and +100%, respectively) and acetate (+26% and +72%, respectively) during the high-RS period. The fecal excretion (g/d) of nonstarch polysaccharides (NSP) also rose by 50% during the high-RS diet, suggesting that the presence of starch in the colon may affect the fermentation of NSP. Subjects reported an increase in flatulence and easier defecation. These results demonstrate that RS has a significant impact on putative markers of colonic health in humans.

Food processing and maize variety affects amounts of starch escaping digestion in the small intestine

Two meals which differed greatly in resistant starch (RS) concentration, but otherwise had similar macronutrient composition (including nonstarch polysaccharides), were fed for breakfast to five subjects with ileostomies. The high-RS meal included bread made from high-amylose maize, uncooked green banana flour, and coarsely ground uncooked wheat. The low-RS meal contained bread made from low-amylose maize, cooked green banana flour, and cooked wheat. The effluent produced over 14 h was analyzed for the total amount of starch escaping digestion. In the low-RS meal 51.8 +/- 6.2 g (mean +/- SD) starch was consumed and 2.4 +/- 0.6 g recovered in the effluent, while for the high-RS meal a total of 52.7 +/- 8.8 g starch was fed and 19.9 +/- 5.2 g recovered in the effluent. The ileostomy results provided additional validation of an in vitro resistant starch assay. Scanning electron micrographs of effluent from one subject who consumed the high-amylose bread revealed that many intact starch granules escaped digestion in the small intestine.

Effect of feeding quandong (Santalum acuminatum) oil to rats on tissue lipids, hepatic cytochrome P-450 and tissue histology

Quandong kernels are a traditional Aboriginal food item; they are rich in oil and contain large amounts of an unusual fatty acid, trans-11-octadecen-9-ynoic acid (santalbic acid), but it is not known whether this acid is absorbed and/or metabolized. The oil was fed at 12.6% of total energy content in semi-synthetic diets to groups of male Sprague-Dawley rats for 10 and 20 days. Santalbic acid was found in the lipids of plasma, adipose tissue, skeletal muscle, kidney, heart and liver but not in brain. Hepatic microsomal cytochrome P-450 activity in animals fed for 20 days was significantly higher (P < 0.05) than in controls. Histopathological examination did not reveal any lesions in the tissues of any animal fed quandong oil. The fact that santalbic acid was readily absorbed, widely distributed in tissues and was associated with an elevated level of hepatic cytochrome P-450 indicates that further studies are required to investigate whether or not there is a hazard associated with the human practice of consuming quandong kernels.

Evidence for the in vivo deamidation and isomerization of an asparaginyl residue in cytosolic serine hydroxymethyltransferase

Rabbit liver cytosolic serine hydroxymethyltransferase exists in several subforms which have different isoelectric points. Incubation of the purified enzyme with chymotrypsin cleaves the enzyme at Trp14. The released amino-terminal 14-mer peptide was shown to exist in three forms of equal concentration. The peptides differ in structure only at the asparaginyl residue at position 5. In addition to asparagine at this position we found both aspartyl and isoaspartyl residues. The deamidation of Asn5 does not appear to occur during the purification of the enzyme. The in vitro rate of deamidation of Asn5 in the enzyme is more than 5-fold slower than the rate of deamidation of this residue in the free 14-mer peptide. The isoaspartyl residue at position 5 serves as a substrate for protein carboxyl methyltransferase both in the free 14-mer peptide and the native enzyme. The enzyme which has had the amino-terminal 14 residues removed by digestion with chymotrypsin still exists in several forms with different isoelectric points. Reaction of peptides from this enzyme with carboxyl methyltransferase suggests that there is at least one more asparaginyl residue in this enzyme other than Asn5 which has undergone deamidation with the formation of isoaspartyl bonds.