Influence of carcinogen binding by lactic acid-producing bacteria on tissue distribution and in vivo mutagenicity of dietary carcinogens

The aims of this investigation were to determine whether viable cultures of lactic acid-producing organisms (LAB) can bind dietary carcinogens and to assess the consequences of binding for the absorption from the gut, distribution in the body and in vivo genotoxicity of ingested carcinogens. The carcinogens used in this study were ones known to be present in the human diet, namely benzo[a]pyrene (B(a)P, aflatoxin B1 (AFB1) and the cooked food carcinogens 2-amino-3-methyl-3H-imidazo[4,5-f]quinoline (IQ), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 5-phenyl-2-amino-1-methylimidazo [4,5-f]pyridine (PhIP) and 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2). They represent a range of structural types so that the specificity of any binding effects could be addressed. Of the carcinogens tested, B(a)P and Trp-P-2 were bound most effectively by the two LAB strains Bifidobacterium longum and Lactobacillus acidophilus. AFB1 was poorly bound, while MeIQx, MeIQ, PhIP and IQ were bound to an intermediate degree. The extent of the binding of the heterocyclic amine carcinogens was dependent on the pH conditions during incubation and this effect was more apparent with B. longum than with L. acidophilus. Using the host-mediated assay (HMA), an in vivo bacterial mutation assay, it was demonstrated that the administration of bacterial cell suspensions of B. longum and L. acidophilus did not lead to a reduction in induced mutagenicity by MeIQ, MeIQx or Trp-P-2, detectable in the liver of treated mice compared with controls. The lack of a protective effect could not be attributed to a short period of contact between bacterial cells and mutagens, since similar results were obtained after preincubating bacteria and mutagens together at pH 5 for 50-60 min, to maximize the binding, before gavaging the mice. Lack of activity of B(a)P in the HMA prevented the determination of the effect of LAB on genotoxicity of the polycyclic aromatic hydrocarbon. However, it is clear from the radiolabel distribution study that the amount of the carcinogen entering the blood was not significantly reduced by B. longum administration. In addition, the amount of radiolabelled B(a)P that reached the target organs (liver, lungs and heart) was also not affected by the LAB administration. A similar lack of inhibitory effect of B. longum on blood concentration and accumulation in the liver of Trp-P-2 was apparent. The results of the present study suggest that although LAB may bind carcinogens in vitro, this does not lead to major changes in absorption and distribution of carcinogens in the body, or in their genotoxic activity in the liver.     

Do vaginal lactobacilli prevent preterm labour?

OBJECTIVE: To determine the prevalence of Lactobacillus spp. in vaginal flora during pregnancy and to assess the protective effects of lactobacilli against preterm labour. DESIGN: Cross-sectional analysis of Lactobacillus spp. in the vaginal flora of the pregnant coloured population of the Western Cape. PARTICIPANTS: A total of 480 consecutive pregnant women, aged 13-48 years, seen at their first visit to the Tygerberg Hospital antenatal clinic. MAIN OUTCOME MEASURES: Preterm labour, i.e. before 34 and 37 weeks' gestation, premature rupture of membranes, intra-uterine growth retardation and perinatal deaths. RESULTS: A total of 163 patients had negative cultures and 317 positive cultures for lactobacilli, aerobes or both. Delivery before 37 weeks occurred in 18% and 20% of the two groups, respectively. Lactobacillus only was cultured from 116 patients and Lactobacillus and/or other aerobes from 201 patients. Preterm labour occurred in 20% of the first group and in 19% of the second group. The perinatal outcome in patients from whom lactobacilli only were cultivated did not differ from patients from whom other aerobes and lactobacilli or other aerobes only were cultured. CONCLUSION: In patients at high risk for preterm labour, the presence of lactobacilli in the vagina does not seem to play a protective role.     

Hepatitis C virus genotypes in liver transplant recipients: impact on posttransplant recurrence, infections, response to interferon-alpha therapy and outcome

BACKGROUND: End-stage liver disease due to hepatitis C virus (HCV) is the most common indication for liver transplantation in U.S. veterans. We investigated the influence of HCV genotypes on the incidence and timing of recurrent HCV hepatitis, survival, infectious morbidity, and response to interferon-alpha therapy in this unique patient population. METHODS: HCV genotype was determined by direct sequencing of the NS5 region of HCV with type-specific primers. RESULTS: Genotype 1a (66%, 32/47) was the predominant genotype. Type 1b was found in 25% (12/47) of patients and type 2b was found in 9% (4/47). Histopathologically recurrent HCV hepatitis developed in 53% (25/47) of the patients after transplantation. This group included 45% (14/31) of the patients with type 1a, 67% (8/12) of the patients with type 1b, and 25% (1/4) of the patients with type 2b (P>0.5). The time to recurrence and the severity of HCV recurrence as defined by aminotransferase levels or Knodell scores were not different among the three genotypes. There was a trend toward a higher incidence of major infections in patients with type 1b (75%) versus type 1a (48%) and type 2b (50%) (P=0.11). The response to interferon-a therapy did not differ significantly among the genotypes. Mortality at 5 years was 16% (5/31) in patients with genotype 1a, 42% (5/12) in patients with genotype 1b, and 50% (2/4) in patients with genotype 2b (P=0.06). CONCLUSIONS: The incidence, time to recurrence, and response to interferon-alpha therapy did not differ between the various genotypes in our liver transplant recipients. However, there was a trend toward higher infectious morbidity and overall mortality in patients with genotype 1b after transplantation.     

A system of measuring surface relief and elasticity of the skin

An opticoelectronic system for measurement of a surface microprofile and elasticity of the skin in real time has been developed operating with a source of radiation having small time coherence. The frequency of measurement is 120 Hz, accuracy at least 3 microns. The system can be used for anthropological inspections, study of age and pathological changes in the skin.     

Molecular analysis of ligand binding to the second cluster of complement-type repeats of the low density lipoprotein receptor-related protein. Evidence for an allosteric component in receptor-associated protein-mediated inhibition of ligand binding

The low density lipoprotein receptor-related protein (LRP), a member of the low density lipoprotein receptor gene family, mediates the cellular uptake of a diversity of ligands. A folding chaperone, the 39-kDa receptor-associated protein (RAP) that resides in the early compartments of the secretory pathway inhibits the binding of all ligands to the receptor and may serve to prevent premature binding of ligands to the receptor during the trafficking to the cell surface. To elucidate the molecular interactions that underlie the interplay between the receptor, RAP, and the ligands, we have analyzed and delineated the binding sites of plasminogen activator inhibitor-1 (PAI-1), tissue-type plasminogen activator (t-PA).PAI-1 complexes, RAP, and the anti-LRP Fab fragment Fab A8. To that end, we have generated a series of soluble recombinant fragments spanning the second cluster of complement-type repeats (C3-C10) and the amino-terminal flanking epidermal growth factor repeat (E4) of LRP (E4-C10; amino acids 787-1165). All fragments were expressed by stably transfected baby hamster kidney cells and purified by affinity chromatography. A detailed study of ligand binding to the fragments using surface plasmon resonance revealed the presence of three distinct, Ca2+-dependent ligand binding sites in the cluster II domain (Cl-II) of LRP. t-PA.PAI-1 complexes as well as PAI-1 bind to a domain located in the amino-terminal portion of Cl-II, spanning repeats E4-C3-C7. Adjacent to this site and partially overlapping is a high affinity RAP-binding site located on repeats C5-C7. Fab A8, a pseudo-ligand of the receptor, binds to a third Ca2+-dependent binding site on repeats C8-C10 at the carboxyl-terminal end of Cl-II. Next, we studied the RAP-mediated inhibition of ligand binding to LRP and to Cl-II. As expected, we observed a strong inhibition of t-PA.PAI-1 complex and Fab A8 binding to LRP by RAP (IC50 congruent with 0.3 nM), whereas in the reverse experiment, competition of t-PA. PAI-1 complexes and Fab A8 for RAP binding to LRP could only be shown at high concentrations of competitors (>/=1 microM). Interestingly, even though the equilibrium dissociation constants for the binding of RAP to LRP and to Cl-II are similar, the binding of the ligands to Cl-II is only prevented by RAP at concentrations that are at least 2 orders of magnitude higher than those required for inhibition of ligand binding to LRP. Our results favor models that propose RAP-induced allosteric inhibition of ligand binding to LRP that may require LRP moieties that are located outside Cl-II of the receptor.     

Infectious complications occurring in liver transplant recipients receiving mycophenolate mofetil

PURPOSE: To determine the causes of visual impairment in a population-based group of visually impaired preterm children. METHODS: Ophthalmological examination and magnetic resonance imaging or computed tomography of the brain were performed in all visually impaired preterm children born 1989-95 in V?rmland. RESULTS: Ten of 18 children had periventricular leukomalacia affecting the optic radiation, six had other lesions or malformations in the posterior visual pathways/cortex, but no child had visually impairing retinopathy of prematurity. CONCLUSION: We conclude that cerebral lesions or malformations are common causes of the visual functional deficit in visually impaired children born preterm. Brain damage should be suspected in a prematurely born child who presents with either of the signs: fixation difficulties, strabismus or nystagmus.     

Immunity to p53 induced by an idiotypic network of anti-p53 antibodies: generation of sequence-specific anti-DNA antibodies and protection from tumor metastasis

The general overexpression of p53 by different types of tumor cells suggests that p53 immunity might be generally useful for tumor immunotherapy. We describe here the induction of immunity to p53 and resistance to tumor metastasis using an idiotypic network. Mice were immunized with domain-specific anti-p53 monoclonal antibodies (Ab1): PAb-248 directed to the N-terminus; PAb-246 directed to the specific DNA-binding region; or PAb-240 directed to a mutant p53 that does not bind specific DNA. Immunized mice responded by making anti-idiotypic antibodies (Ab2) specific for the Ab1 inducer. Ab1 PAb-246 induced Ab2 that, like p53 itself, could bind the specific DNA oligonucleotide sequence of the p53 responsive element. Mice immunized with Ab1 PAb-240 or PAb-246 spontaneously made Ab3 anti-p53 antibodies that reflected the specificity of their Ab1 inducers: Ab1 PAb-246 induced Ab3 specific for wild-type p53; PAb-240 induced Ab3 specific for mutant p53. Ab1 PAb-248 induced only Ab2. The spontaneously arising Ab3 were of T cell-dependent IgG isotypes. Peptides from the complementarity determining regions of the Ab1 antibodies PAb-240 and PAb-246 could also induce Ab3 anti-p53. Finally, mice that produced Ab3 anti-p53 acquired resistance to tumor metastases. Therefore, an anti-idiotypic network built around certain domains of p53 seems to be programmed within the immune system, specific Ab2 antibodies can mimic the DNA binding domain of p53, and Ab3 network immunity to p53 can be associated with resistance to tumor cells.     

Reducing cancer risk among Native American adolescents

BACKGROUND: This article discusses the development, implementation, and preliminary testing of an intervention to reduce cancer risks through tobacco use prevention and dietary modification among Native American youth in the Northeastern United States. METHODS: The intervention outcome study includes a research design and outcome measurement instruments. In collaboration with Native American communities, reservations, and organizations in the Northeastern United States, implementation of the design quantifies the separate and combined effects of a tobacco use prevention and a dietary modification intervention. RESULTS: Native American youths in the tobacco prevention intervention and in the combined tobacco and dietary intervention increased their knowledge of tobacco facts and their awareness of the motives of tobacco advertising, and showed higher ratings for an ability to resist peer pressure and to refuse offers of tobacco use between pretest and posttest. Youths in the combined intervention were significantly less apt to report smoking of any kind. Youths in the tobacco use prevention-only condition reported significantly less smoking than their counterparts in the dietary modification-only condition and control condition on 4 of 8 measurement items. As for dietary variables, pretest to posttest measurement scores showed that, after receiving the curriculum, youths in the dietary modification intervention and in the combined intervention improved their knowledge of the health implications of consuming dietary fat, fiber, fruits, and vegetables. Youths in the dietary modification and combined intervention also improved their scores of knowledge related to cancer risk-reducing nutritional practices, cultural dietary habits, and healthy food choices available for Native American cultures. Youths in the dietary modification-only condition report significantly increasing their consumption of complex carbohydrates and significantly decreasing their fat intake between pretest and posttest occasions. CONCLUSIONS: Data from this longitudinal study suggest the value of the FACETS curriculum for helping Native American youth reduce their risks for cancer associated with tobacco use and dietary preference and consumption patterns. In particular, results indicate the enhanced effects of the combined tobacco use prevention and dietary modification intervention for preventing tobacco use and for improving youths' knowledge and attitudes with regard to tobacco use and diet. Further, the study demonstrates the value of collaborating with Native American organizations to design a cancer risk-reducing curriculum and to implement tests of that curriculum.