Effect of dietary fats on the incidence of 7,12-dimethylbenz(a)-anthracene-induced tumors in rats

Female rats have been fed high fat diets containing either polyunsaturated or saturated fat. After being fed either of the diets for 4 weeks, some of the animals received an intragastric dose of 7,12-dimethylbenz(a)anthracene (DMBA). At this point, the diets of half of the animals were interchanged so that animals previously fed the polyunsaturated fat diet were fed the saturated fat diet and vice versa. The cumulative incidence of tumor-bearing rats among DMBA-dosed rats was greater when the polyunsaturated fat diet was fed. The mean induction time of tumors decreased and the proportion of tumor-bearing rats which developed malignant tumors increased when the polyunsaturated fat diet was fed. This promotional effect of the polyunsaturated fat diet was exerted only when the diet was fed after DMBA administration.     

Expression of p53 and ALZ-50 immunoreactivity in rat cortex: effect of prenatal exposure to ethanol

Neuronal death is an active process that results in the upregulation of antigens recognized by ALZ-50 and p53. Since prenatal exposure to ethanol can induce the postnatal death of cortical neurons, we examined the effects of ethanol on the in vivo expression of both the ALZ-50-positive antigen and p53. Pregnant rats were fed one of three diets, a liquid diet containing ethanol (Et), an isocaloric and isonutritive diet (Ct), or chow and water (Ch). Segments of frontoparietal cortex from fetuses and pups were examined for ethanol-induced changes (a) in the expression of ALZ-50 and p53 immunoreactivity using a quantitative immunoblotting assay and (b) in the distribution of ALZ-50- and p53-positive cells using immunohistochemistry. In control rats, ALZ-50 identified a 56-kDa peptide that was transiently expressed postnatally and peak expression occurred on postnatal day (P) 6 to P12. In Et-treated rats, peak expression was attained earlier (on P3) and was about three times of that achieved in the controls. The anti-p53 antibody identified three proteins (28, 56, and 58 kDa). Peak expression in control rats occurred during the second postnatal week and only the 58-kDa protein was expressed in appreciable amounts in adult cortex. Each p53-positive protein was affected by ethanol exposure. The 28- and 56-kDa p53-positive proteins were affected by ethanol much in the same way as was the ALZ-50-positive antigen. That is, the timing and amount of peak expression were earlier and lower, respectively, in the Et-treated rats. The postnatal expression of the 58-kDa protein was halved following prenatal exposure to ethanol. Both ALZ-50 and anti-p53 immunoprecipitated proteins are p53- and ALZ-50-positive, respectively. Thus, ethanol alters the expression of the ALZ-50- and p53-positive proteins and presumably the timing of neuronal death in the developing cortex. The parallel effects of prenatal ethanol exposure on the 56-kDa ALZ-50-positive antigen and the 28- and 56-kDa p53-positive proteins and the coprecipitation of the proteins are consistent with the notion that ALZ-50 recognizes a form of p53.     

Surgical management of retinal detachments related to coloboma of the choroid

We examined the influence of extruded chickpeas and wheat relative to casein and wheat in a dimethylhydrazine (DMH)-induced colon tumor study in male Sprague-Dawley rats. The three diets, based on a modified AIN76 rodent diet with fat present at 10 g/100 g dry matter (DM), were as follows: casein with wheat starch (Cas/S) as control, casein with wheat (Cas/W) and chickpeas with wheat (CP/W). All diets were fed from 5 wk of age throughout the 28-wk study. At 28 wk, there was a significantly lower incidence of large intestinal tumors in rats fed Cas/W relative to those fed CP/W ( 11 vs. 56%, chi-square test, P = 0.018). The colonic tumor burden (tumors/tumor-bearing animal) was not different in Cas/W-fed and CP/W-fed rats (1 vs. 1.7), but the tumor mass index was significantly lower in the former group (0.22 vs. 1.21, P = 0.026). Rats fed the CP/W diet had significantly lower plasma cholesterol concentration (P < 0.01) than rats fed the other two diets. The cecal contents of rats fed the CP/W diet had significantly greater relative weights (46%, P < 0.05) than those of the Cas/W-fed rats; this was associated with higher concentrations of all short-chain fatty acids. Fecal analyses showed significantly (P < 0.05) higher concentrations of total fat (54%), total steroids (83%) and secondary bile acids (179%) in the CP/W-fed rats relative those fed Cas/W. There were higher concentrations of nitrogen in the feces of CP/W rats relative to the Cas/W-fed rats (84%, P < 0.05), associated with greater fecal weights (67%, P < 0.05). Although wheat and its fibers have been shown to be protective against DMH-induced cancers in rats, this was not the case in this study in which chickpeas (45 g/100 g diet) provided the protein and were an important source of soluble fiber. Elevated fat, secondary bile acid concentrations and/or nitrogenous compounds could be responsible for the increased colon tumorigenesis seen and may reflect a legume effect.     

Influence of diets containing high and low risk factors for colon cancer on early stages of carcinogenesis in human flora-associated (HFA) rats

Germ-free rats colonised with a human intestinal flora were fed diets containing high risk (HR) or low risk (LR) factors for colorectal cancer, and putative biomarkers were evaluated in the colonic mucosa; (i) proliferation, (ii) 1,2-dimethylhydrazine (DMH)-induced aberrant crypt foci and (iii) DMH-induced DNA damage. The HR diet was high in fat (45% of calories) and low in calcium and fibre, reflecting levels characteristic of typical western diets. The LR diet was low in fat (<5% of calories), and high in calcium and fibre. The nutrient/energy ratio of the two diets were similar. Mucosal crypt cell proliferation, assessed after microdissection, was higher on the LR diet (mean number of mitoses per crypt was 2.65 on the LR diet, and 1.62 on the HR diet; P < 0.05). Aberrant crypt foci (ACF) were assessed in the mucosa 12 weeks after DMH treatment. On the HR diet there were significantly more small ACF with 1 and 2 crypts per focus, but fewer ACF with 3, 5 and 7 or more crypts per focus. There was no significant difference in total ACF or the total number of crypts. The effect of diet on DNA damage in the colon was assessed in vivo by the comet assay. Animals were fed a HR or LR diet for 12 weeks before treatment with DMH or saline. For carcinogen-treated animals, DNA damage was significantly higher in colon cells from animals on the HR diet. On the LR diet both DNA damage and the induction of small ACF were reduced despite an increase in cell proliferation. The increase in large ACF on the LR diet may be attributable to elevated crypt cell proliferation possibly increasing crypt fission rates.     

Effects of cocaethylene on dopamine and serotonin synthesis in Long-Evans and Sprague-Dawley brains

BACKGROUND: Primary liver cancer is an important health problem in Korea, where hepatitis B virus (HBV) infection is prevalent. The authors conducted a prospective cohort study to evaluate the protective effect of HBV vaccination against liver cancer in adults. METHODS: A total of 370,285 males aged > or = 30 comprised the study population. They were clinically free of liver diseases, and had not been vaccinated against HBV at enrolment. The results of HBV surface antigen (HBsAg) and antibody to HBsAg (anti-HBs) marker positivity and those of the vaccination programme which took place during 1985 were used for the construction of the cohort. About 5% (n = 18,914) were HBsAg positive, 78,094 were anti-HBs positive, and 273,277 were negative for both. Among the candidates for HBV vaccination (n = 273,277), 35,934 (13.2%) people had been vaccinated against HBV during 1985. Cases of liver cancer were ascertained by record linkage and from medical records covering 1986-1989. A multivariate log-linear model was used to test statistical significance and to estimate relative risks (RR). RESULTS: The total follow-up period was 1,404,566 person-years, with an average of 3 years and 10 months. A total of 302 incident cases were ascertained. The overall incidence rate of liver cancer was 21.7 per 100,000 person-years. With reference to the incidence level among the unvaccinated and uninfected, the RR of primary liver cancer among the chronically infected and that of the unvaccinated and infected was 18.1 (95% CI: 14.2-22.9) and 0.34 (95% CI: 0.19-0.60), respectively. The RR among the vaccinated group was 0.58 (95% CI: 0.31-1.09). CONCLUSIONS: This study suggested that artificial immunization through HBV vaccination, even in adulthood, reduces the risk of liver cancer. It might also offer a practicable means of primary prevention, especially in areas with hyperendemicity of HBV infection.     

Angiotensin-converting enzyme gene polymorphism is associated with coronary heart disease in non-insulin-dependent diabetic patients evaluated for 9 years

OBJECTIVES: To assess effects of vaccination against fescue toxicosis on weight gain, serum prolactin and cholesterol concentrations, and alkaline phosphatase (ALP) activity in mice fed an endophyte-infected (EI) or endophyte-free (EF) fescue diet. ANIMALS: 50 six-week-old male BALB/c mice. PROCEDURE: Mice were randomly allocated to the following 5 groups: 1, vaccinated intraperitoneally with a bovine serum albumin-ergotamine (EG) conjugate and fed an EI fescue diet; 2, orally vaccinated with cholera toxin (CT) subunit B-EG conjugate mixed with free CT and fed an EI fescue diet; 3, not vaccinated and fed an EI fescue diet; 4, passively vaccinated with monoclonal antibodies specific for ergovaline (EV) and fed an EI fescue diet; and 5, not vaccinated and fed an EF fescue diet. RESULTS: Antibodies against EG and EV were in serum of mice of groups 1 and 4, respectively. Secretory IgA and IgG coproantibodies against EG were induced in mice of group 2. Weight increased in groups 1 and 2 and tended to be increased in group 4 versus group 3. Prolactin concentration was similar in all groups; cholesterol concentration was decreased in groups 1, 3, and 4, compared with group 5. Compared with that in group 5, serum ALP activity decreased in groups 1 and 4 and was further decreased in group 1, compared with that in groups 2 and 3; it was negatively correlated with anti-EG titer. CONCLUSIONS AND CLINICAL RELEVANCE: Induction of anti-EG antibodies and administration of EV monoclonal antibodies tended to increase short-term weight gain in this murine model of fescue toxicosis. However, systemic IgG antibodies against EG or EV antibodies were not protective against decreases in serum ALP activity and cholesterol concentrations. Clinical significance of decreased ALP activity associated with vaccination is unknown, but represents a worsening of a response often associated with fescue toxicosis in cattle.     

Oral and parenteral vaccination of mice with protein-ergotamine conjugates and evaluation of protection against fescue toxicosis

Acremonium coenophialum produces ergopeptide alkaloids in tall fescue (Festuca arundinacea Schreb.). These ergot alkaloids decrease serum alkaline phosphatase (ALP) activity, serum cholesterol and prolactin concentrations, as well as average daily gains (ADG) in cattle. The objective of this study was to evaluate the protection of anti-ergotamine antibodies induced by either oral or parenteral vaccination with protein-ergotamine conjugates or passive vaccination with anti-ergovaline, monoclonal antibodies in a murine model of fescue toxicosis. Ergotamine (EG) was conjugated to bovine serum albumin (BSA) and cholera toxin subunit B (CTB) by the Mannich reaction. Mice were blocked based on weight and randomly allocated into five groups of 10 mice each. Treatment groups were as follows: (1) group vaccinated intraperitoneally (ip) with a BSA-EG conjugate and fed an endophyte-infected (EI) fescue diet (BSA-EG group); (2) group orally vaccinated with a CTB-EG conjugate mixed with free cholera toxin (CT) and fed an EI fescue diet (CTB-EG group); (3) nonvaccinated group fed an EI fescue diet (EI group); (4) group passively vaccinated with anti-ergovaline, monoclonal antibodies and fed an EI fescue diet (MoAB group); and (5) nonvaccinated group fed an endophyte-free (EF) fescue diet (EF group). The EI diet contained 1.5 ppm of Ergovaline (EV), whereas no EV was detected in the EF diet.Respective diets were similar upon nutritional analysis. Unvaccinated mice in the EI group exhibited features of fescue toxicosis as indicated by decreased serum ALP activity and cholesterol, and decreased weight gain as compared to mice in the EF group. Antibodies against EG and EV were present in sera of mice in the BSA-EG and MoAB groups, respectively. Mice orally vaccinated with the CTB-EG conjugate developed secretory IgA (sIgA) antibodies and short-lived, systemic IgG responses against EG. Weight gains were increased in the BSA-EG and CTB-EG groups and tended to be increased in the MoAB group vs. the unvaccinated EI group. Serum ALP activity was decreased in the BSA-EG and MoAB groups as compared to the EF group. Serum ALP activity was further decreased in the BSA-EG vaccinated group as compared to the EI group. Cholesterol concentrations were decreased in the EI, BSA-EG and MoAB groups as compared to the EF group. Prolactin concentrations were similar in all groups.     

Dietary vitamin D affects cell-mediated hypersensitivity but not resistance to experimental pulmonary tuberculosis in guinea pigs

Outbred, Hartley strain guinea pigs were fed purified diets varying only in their levels of vitamin D. The amounts of vitamin D in the diets were adjusted to represent 0, 25, 50, 100, or 200% of the recommended level (1,180 IU/kg of body weight) for guinea pigs. In some experiments, half of the animals in each diet group were vaccinated with Mycobacterium bovis BCG vaccine at the time the diets were introduced. Six weeks later, all guinea pigs were infected by the respiratory route with a low dose of virulent M. tuberculosis H37Rv. Vitamin D-deficient animals exhibited marked reductions in levels of the major vitamin D metabolite, 25-hydroxyvitamin D3, in plasma. Altered vitamin D intake was accompanied by changes in antigen (purified protein derivative)-induced, cell-mediated immune responses both in vivo (tuberculin hypersensitivity) and in vitro (lymphoproliferation). Dermal tuberculin reactivity developed more slowly in vitamin D-deficient guinea pigs but eventually achieved normal levels. The proliferation of splenocytes cultured with purified protein derivative was suppressed by both deficiency and excess of dietary vitamin D. Vitamin D status did not affect the abilities of naive guinea pigs to control primary, pulmonary tuberculosis, nor did it influence the protective efficacy of BCG vaccination. We conclude that changes in dietary vitamin D are associated with alterations in some cellular immune functions but may not be an important determinant of disease outcome in pulmonary tuberculosis, as has been suggested previously.     

Accelerated viraemia in cats vaccinated with fixed autologous FIV-infected cells

We have vaccinated cats with fixed autologous FIV infected PBMC to determine whether autologous presentation of antigen is capable of inducing a protective immune response against homologous challenge. To this end autologous PBMC were infected with a FIV molecular clone (19k1). When infection was established, cells were inactivated by dialysis against paraformaldehyde. Upon vaccination, cats developed a virus specific immune response as measured by ELISA against the Gag protein of FIV. No antibodies against the envelope protein were detected with a peptide ELISA. Virus neutralizing antibodies however could be detected with a neutralization assay based on infection of CrFK cells, but not in an assay based on infection of primary T-cells. Although vaccination led to the induction of these virus-specific immune responses, vaccinated cats were not protected against homologous challenge but showed an accelerated viraemia upon infection. This was shown both by PCR and cell-associated viral load. The possible mechanisms underlying this observation are discussed in this paper.     

Isotype responses to candidate vaccine antigens in protective sera obtained from mice vaccinated with irradiated cercariae of Schistosoma mansoni

In experimental schistosomiasis, sera of mice multiply vaccinated with radiation-attenuated cercariae of Schistosoma mansoni passively transfer resistance against cercarial challenge to naive mice. To further characterize these sera, we tested their protective capacities in two mouse strains (C57BL/6J and CBA/J) and compared the antigen-specific isotype compositions of the different protective sera by means of the enzyme-linked immunosorbent assay. By using an array of purified schistosomal antigens, the patterns of antibody titers and isotypes differed for each experimental group and antigen. In the most-protective C57BL/6J sera, high levels of immunoglobulin G1 (IgG1), IgG2a, and IgG2b bound to heat shock protein 70 and the integral membrane protein Sm23, whereas recognition of these antigens by less-protective CBA/J sera was lower. Glutathione S-transferase (GST) was recognized predominantly by IgM antibodies of all vaccinated groups, and a significant portion of this response was directed against carbohydrate epitopes. Antibodies specific for triosephosphate isomerase, paramyosin, and Sm32 (hemoglobinase) were present in less-protective sera and thus seem less relevant for passive transfer of resistance. The results of this study suggest a contribution of IgG antibodies specific for heat shock protein 70 and Sm23, and possibly a contribution of GST-specific IgM antibodies, to the protective effect of sera from C57BL/6J mice vaccinated with irradiated cercariae.     

Effect of vaccination of hens with an avirulent strain of Salmonella typhimurium on immunity of progeny challenged with wild-Type Salmonella strains

The avirulent Salmonella typhimurium chi3985 was used to vaccinate white leghorn chickens at 16 and 18 weeks of age, and the effect of maternal antibody on Salmonella colonization of progeny of vaccinated hens was assessed with S. typhimurium F98 or chi3985. Progeny of hens that had been vaccinated at 1 and 3 or 2 and 4 weeks of age with chi3985 were used to determine the effect of maternal immunity on vaccine efficacy. Vaccination of hens induced long-lasting Salmonella-specific antibodies which were transferred into eggs and were detected as immunoglobulin G (IgG) in the egg yolk. Maternal antibody was detected in the progeny of vaccinated birds as IgG and IgA in serum and intestinal fluid, respectively. The titer of maternally transmitted IgG or IgA was highest in the first week of life of the progeny and declined with age. Maternal antibodies prevented colonization of the chicks by S. typhimurium chi3985 and reduced colonization by S. typhimurium F98. Overall, chicks from vaccinated hens had significantly higher antibody responses than did the progeny of nonvaccinated hens after oral infection with Salmonella strains. Maternal antibody reduced the efficacy of vaccination of progeny with chi3985 at 1 and 3 weeks of age. But vaccination at 2 and 4 weeks of age induced excellent protection against challenge with S. typhimurium F98 or S. enteritidis 27A PT 8 in birds from vaccinated hens and in specific-pathogen-free chickens. Vaccination of chickens at 2 and 4 weeks of age has been shown to protect the birds against challenge with homologous and heterologous Salmonella serotypes. A combination of vaccination of adult animals and use of the progeny of vaccinated birds will enhance effective control of Salmonella infections in the poultry industry. This will complement the present control of Salmonella-associated food poisoning caused by Salmonella enteritidis in eggs because the avirulent S. typhimurium vaccine strain chi3985 induced excellent protection against S. enteritidis in chickens.     

Circulating p53 antibodies as early markers of oral cancer: correlation with p53 alterations

p53 aberrations are early events in the pathogenesis of betel- and tobacco-related oral malignancies. Accumulation of p53 protein in oral lesions may elicit a humoral immune response against p53 protein in these patients. p53 antibodies (Abs) were analyzed in 183 sera obtained from patients with premalignant or malignant oral lesions and normal individuals by enzyme-linked immunoassay using recombinant p53 protein as antigen. These results were correlated with accumulation of p53 protein in patients' matched oral tissue specimens. Circulating p53 Abs were observed in 24 of 70 (34%) cancer patients and 15 of 50 (30%) patients with premalignant oral lesions. p53 Abs showed a significant association with increase in tumor size and dedifferentiation of tumors, factors indicative of poor prognosis. Expression of p53 protein was analyzed in 43 matched oral lesions (18 premalignant and 25 malignant cases). All the p53-seropositive patients (7 leukoplakia and 11 squamous cell carcinoma) showed elevated levels of p53 protein in matched oral lesions. However, the total number of patients seropositive for p53 Abs was lesser than that of patients exhibiting p53 protein accumulation in oral lesions. Four of the 63 normal healthy individuals who were heavy consumers of tobacco (smoking/chewing) and betel were found to be positive for p53 Abs. Detection of circulating p53 Abs in patients with premalignant oral lesions suggests that humoral immune response against p53 protein is an early event in oral oncogenesis and may be a surrogate marker for both p53 alteration and preclinical cancer.     

Influence of the specific T cell response on seroconversion after measles vaccination in autologous bone marrow transplant patients

Six patients who were seronegative to measles after autologous bone marrow transplantation (ABMT) were vaccinated with a live attenuated measles vaccine. The specific T helper cell response was studied by measuring lymphocyte proliferation induced by measles antigen and B cell response by measles specific IgG by ELISA. Blood samples were drawn before, at 1-3 months, and at 1 year after vaccination. It was found that a pre-existing T cell response correlated with an impaired B cell response 1 year after vaccination (r = 0.83, P = 0.04), whereas no correlation was found between IgG titers before vaccination and IgG titer increase, or T cell response after vaccination. Furthermore, there was a transient negative correlation between the T cell response at 1-3 months after vaccination and the T cell response before vaccination (r = -0.90, P = 0.04) that became positive at 1 year after vaccination (r = 0.90, P = 0.02). In conclusion, in patients seronegative to measles who were revaccinated with measles vaccine after ABMT, a pre-existing T cell response correlated with an impaired B cell response, while pre-existing low-level IgG antibodies had no significant influence on the IgG titer rise. A sustained T cell response to measles antigen before vaccination may thus be one possible explanation for measles vaccine failure in ABMT patients.     

Vaccination with glutaraldehyde-fixed bovine respiratory syncytial virus (BRSV)-infected cells stimulates a better immune response in lambs than vaccination with heat-inactivated cell-free BRSV

The lamb model was used to investigate the possible protective effects of vaccination with inactivated viral antigens against experimental infection with bovine respiratory syncytial virus. Two groups of eight lambs were vaccinated with either glutaraldehyde-inactivated cell-associated virus or heat-inactivated cell-free virus and subsequently challenged with live virus, along with a group of naive lambs. The virus was shed for significantly longer periods, and the virus titres in nasal secretions were significantly higher in the group of naive lambs than in the two groups of vaccinated lambs. The period of virus-shedding in nasal secretions and virus titres was significantly lower (p < 0.01) in the group of lambs immunized with the cell-associated preparation. The same antigen stimulated better cellular immune responses as measured by virus-specific cytotoxicity or by virus-specific lymphocyte proliferation. However, priming with inactivated vaccines had no significant effect on lymphocyte responses to phytohaemagglutinin, which was found to be significantly reduced (p < 0.01) following challenge with live virus.     

D-amphetamine and L-5-hydroxytryptophan-induced behaviours in mice with genetically-altered expression of the alpha2C-adrenergic receptor subtype

We have analyzed human T-cell responses in parallel with serum immunoglobulin G (IgG) antibody levels after systemic vaccination with the Norwegian group B Neisseria meningitidis outer membrane vesicle (OMV) vaccine. Ten adult volunteers, with no or very low levels of serum IgG antibodies against meningococci, received three doses intramuscularly of the OMV vaccine (at weeks 0, 6, and 46). T-cell proliferation against the OMV vaccine, purified outer membrane proteins (PorA and PorB), and control antigens (Mycobacterium bovis BCG vaccine and tetanus toxoid) was measured by thymidine incorporation of peripheral blood mononuclear cells before and after vaccination. The results showed that vaccination with OMV elicits strong primary and booster T-cell responses specific to OMV as well as the PorA (class 1) protein and significant, but markedly lower, responses against the PorB (class 3) protein. The median responses to OMV and PorA were 26 and 16 times the prevaccination levels, respectively. Most of the vaccinees showed low T-cell responses against OMV and PorA before vaccination, and the maximum T-cell responses to all vaccine antigens were usually obtained after the second vaccine dose. We found a positive correlation between T-cell responses and anti-OMV IgG antibody levels (r = 0.50, P < 0.0001, for OMV and PorA). In addition, we observed a progressive increase in the percentage of CD45R0+ (memory) CD4-positive T cells (P = 0.002). In conclusion, we have shown that the Norwegian OMV vaccine against meningococcal B disease induced antigen-specific T-cell responses, kinetically accompanied by serum IgG responses, and that vaccination increased the proportion of memory T-helper cells.     

Effect of missed hemodialysis treatments on mortality in patients with end-stage renal disease

Dietary fibre is believed to protect against a range of Western diseases, including colorectal cancer. Whole plant cell walls make up most of the dietary fibre in Western diets, but their role in disease protection has rarely been studied. At least in vitro, suberized plant cell walls possess novel properties that suggest they could have exceptional potential for cancer protection. Our aim was to test in a rat model the abilities of suberized cell walls from potato skins and commercial cork to decrease gastrointestinal transit time and to protect against the development of aberrant crypts, an early marker of colon cancer. Groups of six rats were fed a modified AIN-76 diet as the control diet and this diet supplemented with 5% dietary fibre from the following sources: commercial cork, commercial-cork cell walls and potato-skin cell walls. A diet supplemented with wheat bran was used as a positive control. The colon carcinogen IQ (2-amino-3-methylimidazo[4,5-f]quinoline) was administered for 3 weeks and after another 12 weeks the number of aberrant crypts determined. Transit times were determined after feeding the diets for 4 weeks. Compared with rats fed the control diet, rats fed diets supplemented with the suberized cell-wall preparations had decreased transit times and had significantly fewer aberrant crypts, with no aberrant crypt foci containing four or more crypts. The diets supplemented with suberized cell walls were more effective than thediet supplemented with wheat bran. We conclude that suberized and lignified cell walls, but particularly suberized, may play an important role in protection against Western diseases, including colorectal cancer. Failure to distinguish suberized and lignified plant cell walls from other sources of non-starch polysaccharides may provide a major limitation in current assessments of the role of dietary fibre in preventing colorectal cancer in humans.     

Low dietary protein impairs blood coagulation in BHE/cdb rats

The influence of dietary protein on blood coagulation tests was evaluated in BHE/cdb rats. Three experiments were conducted in order to compare effects of diets with low (8 g/100 g diet) or high (38 g/100 g diet) protein, to establish values for coagulation tests at intermediate (12-30 g/100 g diet) concentrations of dietary protein, and to compare feeding identical quantities of diets with 8 g protein/100 g diet vs. 18 g protein/100 g diet. After 4 wk of feeding the semipurified diets, bleeding time exceeded 15 min in the groups fed low protein diets, compared to a range of 3-6 min for the groups fed high protein diets. Several in vitro tests of coagulation were abnormal in the rats fed low protein diets. For example, prothrombin time averaged 27 +/- 8 s in rats fed 8 g protein/100 g diet plus beef tallow, but 17 +/- 1 s in rats fed 38 g protein/100 g diet plus tallow. The coagulation deficit in rats fed low protein was not affected by fat source (tallow vs. menhaden oil), but fibrinogen was elevated in rats fed diets with menhaden oil. Conversely, no differences in coagulation tests were observed among rats fed 12-30 g protein/100 g diet. Bleeding times ranged from 7 to 9 min, and prothrombin time was 17-18 s. Significant differences in plasma fibrinogen concentration and prothrombin time were observed in rats fed 8 vs. 18 g protein/100 g diet at a fixed rate of 6 g/100 g body weight. Platelet and blood cell numbers were unaffected by dietary protein. The evidence for multiple deficits in the coagulation system suggests that hepatic function in BHE/cdb rats may become impaired when the rats are fed low protein diets of the composition used here.     

Genetic vaccination against the melanocyte lineage-specific antigen gp100 induces cytotoxic T lymphocyte-mediated tumor protection

Melanocyte lineage-specific antigens, such as gp100, have been shown to induce both cellular and humoral immune responses against melanoma. Therefore, these antigens are potential targets for specific antimelanoma immunotherapy. A novel approach to induce both cellular and humoral immunity is genetic vaccination, the injection of antigen-encoding naked plasmid DNA. In a mouse model, we investigated whether genetic vaccination against the human gp100 antigen results in specific antitumor immunity. The results demonstrate that vaccinated mice were protected against a lethal challenge with syngeneic B16 melanoma-expressing human gp100, but not control-transfected B16. Both cytotoxic T cells and IgG specific for human gp100 could be detected in human gp100-vaccinated mice. However, only adoptive transfer of spleen-derived lymphocytes, not of the serum, isolated from protected mice was able to transfer antitumor immunity to nonvaccinated recipients, indicating that CTLs are the predominant effector cells. CTI, lines generated from human gp100-vaccinated mice specifically recognized human gp100. Interestingly, one of the CTL lines cross-reacted between human and mouse gp100, indicating the recognition of a conserved epitope. However, these CTLs did not appear to be involved in the observed tumor protection. Collectively, our results indicate that genetic vaccination can result in a potent antitumor response in vivo and constitutes a potential immunotherapeutic strategy to fight cancer.     

Special Committee on HIV discusses AIDS, Committee goals

Intraperitoneal glucose tolerance tests were performed at 4-week intervals in groups of weanling rats before and after feeding with maize- or cassava-based diets with and without adequate protein and sublethal cyanide supplementation. Weaning weights were doubled (increase of about 50 g) after 4 weeks on control (maize-based with adequate protein) and protein-replete diets. Weight gain on the protein-deficient diets was much less (22 g or 50%), a pattern maintained by the rats on these diets until the age of 12 weeks. Plasma thiocyanate levels were identical at weaning and after 8 weeks of the control diet but increased by 200-300% after 4 weeks intake of the cassava or cyanide-supplemented feeds. Levels returned to normal in all groups after a further 4 weeks feeding with the control diet. Glucose tolerance (as assessed by the area under the 2 h glucose v. time curve) was impaired to a varying extent in the rats after 4 weeks on the various diets: protein-replete cassava and protein-deficient maize diets by 50% protein-deficient cassava diet by 300%, and cyanide-supplemented protein-deficient maize diet by 150%. The derangement in the rats on the protein-replete cassava diet was unaffected by a further 4 weeks intake of the control diet, unlike in the other groups where there was significant improvement in the glucose tolerance indices at the same time. It is concluded that in growing rats: (1) cassava intake and protein malnutrition may have independent and additive effects on the genesis of glucose intolerance, (2) cyanide supplementation of a cassava-free protein-replete diet has no effect on glucose tolerance.     

Vaccination with DNA encoding an immunodominant myelin basic protein peptide targeted to Fc of immunoglobulin G suppresses experimental autoimmune encephalomyelitis

We explore here if vaccination with DNA encoding an autoantigenic peptide can suppress autoimmune disease. For this purpose we used experimental autoimmune encephalomyelitis (EAE), which is an autoaggressive disease in the central nervous system and an animal model for multiple sclerosis. Lewis rats were vaccinated with DNA encoding an encephalitogenic T cell epitope, guinea pig myelin basic protein peptide 68-85 (MBP68-85), before induction of EAE with MBP68-85 in complete Freund's adjuvant. Compared to vaccination with a control DNA construct, the vaccination suppressed clinical and histopathological signs of EAE, and reduced the interferon gamma production after challenge with MBP68-85. Targeting of the gene product to Fc of IgG was essential for this effect. There were no signs of a Th2 cytokine bias. Our data suggest that DNA vaccines encoding autoantigenic peptides may be useful tools in controlling autoimmune disease.