Activation of Wnt signaling rescues neurodegeneration and behavioral impairments induced by beta-amyloid fibrils.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder, which is probably caused by the cytotoxic effect of the amyloid beta-peptide (Abeta). We report here molecular changes induced by Abeta, both in neuronal cells in culture and in rats injected in the dorsal hippocampus with preformed Abeta fibrils, as an in vivo model of the disease. Results indicate that in both systems, Abeta neurotoxicity resulted in the destabilization of endogenous levels of beta-catenin, a key transducer of the Wnt signaling pathway. Lithium chloride, which mimics Wnt signaling by inhibiting glycogen synthase kinase-3beta promoted the survival of post-mitotic neurons against Abeta neurotoxicity and recovered cytosolic beta-catenin to control levels. Moreover, the neurotoxic effect of Abeta fibrils was also modulated with protein kinase C agonists/inhibitors and reversed with conditioned medium containing the Wnt-3a ligand. We also examined the spatial memory performance of rats injected with preformed Abeta fibrils in the Morris water maze paradigm, and found that chronic lithium treatment protected neurodegeneration by rescuing beta-catenin levels and improved the deficit in spatial learning induced by Abeta. Our results are consistent with the idea that Abeta-dependent neurotoxicity induces a loss of function of Wnt signaling components and indicate that lithium or compounds that mimic this signaling cascade may be putative candidates for therapeutic intervention in Alzheimer's patients.

Anti-proliferative effect of two novel palmitoyl-carnitine analogs, selective inhibitors of protein kinase C conventional isoenzymes.

Previous studies have shown that palmitoyl-carnitine is an anti-proliferative agent and a protein kinase C inhibitor. Two new palmitoyl-carnitine analogs were synthesized by replacing the ester bond with a metabolically more stable ether bond. An LD50 value in the nM range was found in anti-proliferative assays using HL-60 cells and was dependent on the alkyl-chain length. The inhibitory action of these water-soluble compounds on protein kinase C in vitro was greatly increased with respect to palmitoyl-carnitine and was dependent on the length of the alkyl chain. Its effect was mediated by an increase in the enzyme's requirement for phosphatidylserine. Inhibition of the in situ phosphorylation of a physiological platelet protein kinase C substrate and of phorbol ester-induced differentiation of HL-60 cells was also observed. Finally, to test for isoenzyme selectivity, several human recombinant protein kinase C isoforms were used. Only the Ca2+-dependent classic protein kinase Cs (alpha, betaIota, betaIotaIota and gamma) were inhibited by these compounds, yet the activities of casein kinase I, Ca2+/calmodulin-dependent kinase and cAMP-dependent protein kinase were unaffected. Thus, these novel inhibitors appear to be both protein kinase C and isozyme selective. They may be useful in assessing the individual roles of protein kinase C isoforms in cell proliferation and tumor development and may be rational candidates for anti-neoplasic drug design.

How do researchers influence decision-makers? Case studies of Mexican policies.

Though the problems translating or applying research in policy-making are legion, solutions are rare. As developing countries increase their capacities to develop effective local solutions to their health problems, they confront the research/policy dilemma. Yet few descriptive studies of research-policy links can be found from developing countries, and the relevance of European and North American models and data is questionable. We report the results of a descriptive study from Mexico of the relationship between health research and policy in four vertical programmes (AIDS, cholera, family planning, immunization). We interviewed 67 researchers and policy-makers from different institutions and levels of responsibility. We analyzed interviewee responses looking for factors that promoted or impeded exchanges between researchers and policy-makers. These were, in turn, divided into emphases on content, actors, process, and context. Many of the promoting factors resembled findings from studies in industrialized countries. Some important differences across the four programmes, which also distinguish them from industrialized country programmes, included extent of reliance on formal communication channels, role of the mass media in building social consensus or creating discord, levels of social consensus, role of foreign donors, and extent of support for biomedical versus social research. We recommend various ways to increase the impact of research on health policy-making in Mexico. Some of the largest challenges include the fact that researchers are but one of many interest groups, and research but one input among many equally legitimate elements to be considered by policy-makers. Another important challenge in Mexico is the relatively small role played by the public in policy-making. Further democratic changes in Mexico may be the most important incentive to increase the use of research in policy-making.

High-affinity binding of fatty acyl-CoAs and peroxisome proliferator-CoA esters to glutathione S-transferases effect on enzymatic activity.

Acyl-CoAs are present at high concentrations within the cell, yet are strongly buffered by specific binding proteins in order to maintain a low intracellular unbound acyl-CoA concentration, compatible with their metabolic role, their importance in cell signaling, and as protection from their detergent properties. This intracellular regulation may be disrupted by nonmetabolizables acyl-CoA esters of xenobiotics, such as peroxisome proliferators, which are formed at relatively high concentration within the liver cell. The low molecular mass acyl-CoA binding protein (ACBP) and fatty acyl-CoA binding protein (FABP) have been proposed as the buffering system for fatty acyl-CoAs. Whether these proteins also bind xenobiotic-CoA is not known. Here we have identified new liver cytosolic fatty acyl-CoA and xenobiotic-CoA binding sites as glutathione S-transferase (GST), using fluorescent polarization and a acyl-etheno-CoA derivative of the peroxisome proliferator nafenopin as ligand. Rat liver GST and human liver recombinant GSTA1-1, GSTP1-1 and GSTM1-1 were used. Only class alpha rat liver GST and human GSTA1-1 bind xenobiotic-CoAs and fatty acyl-CoAs, with Kd values ranging from 200 nM to 5 microM. One mol of acyl-CoA is bound per mol of dimeric enzyme, and no metabolization or hydrolysis was observed. Binding results in strong inhibition of rat liver GST and human recombinant GSTA1-1 (IC50 at the nanomolar level for palmitoyl-CoA) but not GSTP1-1 and GSTM1-1. Acyl-CoAs do not interact with the GSTA1-1 substrate binding site, but probably with a different domain. Results suggest that under increased acyl-CoA concentration, as occurs after exposure to peroxisome proliferators, acyl-CoA binding to the abundant class alpha GSTs may result in strong inhibition of xenobiotic detoxification. Analysis of the binding properties of GSTs and other acyl-CoA binding proteins suggest that under increased acyl-CoA concentration GSTs would be responsible for xenobiotic-CoA binding whereas ACBP would preferentially bind fatty acyl-CoAs.

[Social sciences and AIDS]. / Ciencias sociales y SIDA.

PIP: The social nature of AIDS and its transmission in the context of social relations that are intimate and resistant to social control, justify assigning the social sciences a significant role in fighting AIDS. The social sciences should be involved in conceptualizing, understanding, and modifying the processes favoring the spread of AIDS and hampering treatment. Various approaches have evolved in the response of the social sciences to AIDS, from a focus on behavior to increased interest in structural aspects and more recently to a concern with issues of power and vulnerability. The social sciences did not contribute much that was new at the Twelfth World Conference on AIDS in Geneva, but some results of previous social science research have been significant, such as affirmation that sex education does not speed initiation of sexual activity and definition of possible strategies for work with intravenous drug users. The work of social scientists has demonstrated the importance of the gender perspective and the need for mechanisms of qualitative and quantitative evaluation, true community participation, and respect for human rights in all actions related to the epidemic. The most immediate challenge for social scientists will be to find ways to reduce the vulnerability resulting from inequality.^ieng

Enhanced differentiation of HL-60 leukemia cells to macrophages induced by ciprofibrate.

Ciprofibrate, an hypolipidaemic peroxisome proliferator, induced differentiation of HL-60 cells. The effect was greatly potentiated by phorbol 12-myristate 13-acetate at a concentration where neither phorbol ester nor ciprofibrate alone had any effect on these cells. As occurs for HL-60 cell differentiation induced by high phorbol ester concentration, the ciprofibrate-induced phorbol ester-dependent differentiation of HL-60 cells proceeded through the monocytic/macrophage pathway and induced the phosphorylation of proteins with similar molecular weights suggesting that increased protein kinase C activity may be involved in the effect. The peroxisome proliferator-activated receptor (PPARalpha) transcription factor is expressed in HL-60 cells, but no changes were observed in its expression upon HL-60 cell differentiation.

Isolation of intact organelles by differential centrifugation of digitonin-treated hepatocytes using a table Eppendorf centrifuge.

A quick subcellular fractionation procedure using differential centrifugation, which is applicable to isolated and cultured cells, is presented. This technique was developed for studying the subcellular localization of phosphorylated proteins in isolated liver cells after various stimuli, but is also applicable to many other situations. The main difference with the usual techniques is that by including digitonin in the homogenization buffer, the procedure is greatly shortened. Furthermore, because the soluble fraction is separated from the particulate fraction very early in the fractionation procedure, subcellular organelles are not exposed to phosphatases and other soluble enzymes such as esterases and proteases during the fractionation. The entire procedure is carried out in an Eppendorf centrifuge, which allows isolation of the cytosolic fraction in less than 1 min, a washed nuclear fraction in about 4 min, a mitochondrial fraction in less than 10 min, and a washed light mitochondrial L fraction in about 40 min. Judging by the behavior of marker enzymes and the morphology of the fractions, the method is highly comparable to classical procedures.

Mexico and Central America.

PIP: This article reviews the literature on migration and HIV/AIDS in Mexico and Central America, including Belize, Costa Rica, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, and Panama. Most migrants travel to the US through Mexico. US-Mexico trade agreements created opportunities for increased risk of HIV transmission. The research literature focuses on Mexico. Most countries, with the exception of Belize and Costa Rica, are sending countries. Human rights of migrants are violated in transit and at destination. Migration policies determine migration processes. The Mexican-born population in the US is about 3% of US population and 8% of Mexico's population. About 22% arrived during 1992-97, and about 500,000 are naturalized US citizens. An additional 11 million have a Mexican ethnic background. Mexican migrants are usually economically active men who had jobs before leaving and were urban people who settled in California, Texas, Illinois, and Arizona. Most Mexican migrants enter illegally. Many return to Mexico. The main paths of HIV transmission are homosexual, heterosexual, and IV-drug-injecting persons. Latino migrants frequently use prostitutes, adopt new sexual practices including anal penetration among men, greater diversity of sexual partners, and use of injectable drugs.^ieng

Overexpression of mdr2 gene by peroxisome proliferators in the mouse liver.

BACKGROUND: In mice, fibrates induce mdr2 gene expression, and its encoded P-glycoprotein in the canalicular domain of hepatocytes, as well as increasing biliary phospholipid output. It is not known whether this effect is restricted to fibrates or is a common property of peroxisome proliferators. AIMS: To test the effect of structurally unrelated peroxisome proliferators on mdr2 gene expression and biliary phospholipid output, and to explore the molecular mechanism(s) of mdr2 gene induction. METHODS: Male CFI mice were fed on a diet supplemented with several peroxisome proliferators: phenoxyacetic acid herbicides, plasticizers, acetylsalicylic acid and partially hydrogenated fish oil. RESULTS: Increased levels of mdr2 mRNAs, assessed by Northern blot analysis, were observed in the liver of mice treated with phenoxyacetic acid herbicides: 2,4,5-trichlorophenoxyacetic acid 570+/-133%, 2,4-dichlorophenoxyacetic acid 233+/-54% (p<0.005); plasticizers: di-(2-ethylhexyl)phthalate 282+/-78%, di-(isoheptyl)phthalate 163+/-40%, phthalic acid dinonyl ester 225+/-48% (p<0.01); and partially hydrogenated fish oil 372+/-138% (p<0.005). P-glycoprotein traffic ATPase content increased in the canalicular domain of hepatocyte of mice treated with the herbicide 2,4,5-trichlorophenoxyacetic acid and with partially hydrogenated fish oil (108% and 87%, respectively, p<0.05) as well as biliary phospholipid output (106% and 74%, respectively, p<0.05). In 2,4,5-trichlorophenoxyacetic acid-fed mice we found five-fold increase on mdr2 transcription rate, assessed by nuclear run-off assay. CONCLUSIONS: Peroxisome proliferators induce mdr2 gene, its encoded P-gp in the canalicular domain of hepatocytes and increase biliary phospholipid output. The modulation of mdr2 gene might be part of the pleiotrophic response of peroxisome proliferation in mice liver and seems to be regulated mainly at a transcriptional level.

Development and evaluation of a health education intervention against Taenia solium in a rural community in Mexico.

A comprehensive study was undertaken in a rural community in the state of Morelos, Mexico to evaluate health education as an intervention measure against Taenia solium. An educational program was developed to promote recognition and knowledge of the transmission of the parasite and to improve hygienic behavior and sanitary conditions that foster transmission. The effects of educational intervention were evaluated by measuring changes in knowledge and practices and prevalence of human taeniasis and swine cysticercosis before and after the campaign. The health education strategy was implemented with the active participation of the population based on the information obtained from a sociologic study. A questionnaire was designed and used before, immediately after the intervention, and six months later. Statistically significant improvements occurred in knowledge of the parasite, its life cycle, and how it is acquired by humans; however, changes in behavior related to transmission were less dramatic and persistent. The prevalences of cysticercosis in pigs at the start of the education intervention were 2.6% and 5.2% by lingual examination and antibody detection (immunoblot assay), respectively, and approximately one year after the intervention they were 0% and 1.2% (P < 0.05). These changes were accompanied by significant reductions in the reported access of pigs to sources of infection and freedom to roam. We conclude that health education, developed along with community involvement, reduced opportunities for transmission of T. solium in the human-pig cycle.

PIP: Neurocysticercosis is an important health problem in Mexico, as well as in many other countries of Latin America, Asia, and Africa where conditions permit completion of the cestode's life cycle in pigs and humans. A study was conducted in a rural community in the state of Morelos, Mexico, to determine whether health education could be an effective measure against Taenia solium. An educational program was developed with community input to promote recognition and knowledge of the transmission of the parasite and to improve hygienic behavior and sanitary conditions which foster transmission. The effects of the educational intervention were then assessed by measuring changes in knowledge, practices, and the prevalence of human taeniasis and swine cysticercosis before and after the campaign. Statistically significant improvements occurred with regard to knowledge of the parasite, its life cycle, and how it is acquired by humans. However, changes in behavior related to transmission were less marked and persistent. Lingual examination and antibody detection found cysticercosis among 2.6% and 5.2% of pigs, respectively, at the start of the intervention. At approximately 1 year after the intervention, prevalences had declined to 0% and 1.2%. The decline was accompanied by significant reductions in the reported access of pigs to sources of infection and freedom to roam.

["We do what we can": health service providers facing the utilization problem]. / "Hacemos lo que podemos": los prestadores de servicios frente al problema de la utilización.

This study presents the second part of the general results obtained by a qualitative study conducted within the National Health Survey II. The object of this study was to identify main patterns and micro-social determinants which affect the process of selection and utilization of health services in order to propose policies aimed at more equity, quality and efficiency in health service delivery. The study was conducted in urban areas among the middle and middle-low class sectors. A total of 192 individual open-ended interviews and eight focus groups were completed among health users in four cities. Also, 61 service providers both from public and private services were interviewed. Since a previous work reported findings related to health service users, this study focuses only on the results pertaining to health service providers. The first part briefly discusses the study design which allowed to explore the meaning that actors--health service providers--attach to their job and working conditions. The second part presents the main findings. The sense of economic and material precariousness with which health providers from public institutions do their work is among the most important results. Common conflicts between health service users and providers are also mentioned, mainly those which arise from the organizational problems of the health center and from the scarcity of the basic drug stock. The third part reports the main coincidences and divergences between health service users and providers. Some of the divergences may be the reason for the under-utilization of health services. The work concludes with a series of policy recommendations aimed at improving the quality and opportunity of health services provided by public institutions for the needs of the population.

[From "how many" to "why": the utilization of health services from the perspective of the users]. / Del "cuánto" al "por qué": la utilización de los servicios de salud desde la perspectiva de los usuarios.

Parallel to the National Health Survey-II, in 1994 a qualitative study was conducted on the patterns and microsocial determinants of health services utilization. The study was conducted in eight urban areas from all over the country among middle class and middle-low class sectors. A total of 192 individual open-ended interviews and eight focus groups were completed among users of health services; 61 service providers both from public and private services were also interviewed. This paper reports the main findings regarding the users' perspective. The first part summarizes the conceptual and methodological design. The second part presents the results from the users' point of view. Individuals distinguish between "becoming sick" and "falling sick"; preventive measures are adopted when becoming sick, in order to avoid falling sick. Another finding refers to the population tendency to add up different and even contradictory curative paradigms, as opposed to the modern medical paradigm which tends to exclude any competing alternative knowledge. A third series of findings refers to the dilemmas that utilizing health services poses for the population, given the high costs, and the low quality that characterize these services, according to the users' point of view. This paper concludes with a series of recommendations for policies, aimed at improving the quality of the health services provided to the population.

Microbial removal of chlorinated phenols during aerobic treatment of effluents from radiata pine kraft pulps bleached with chlorine-based chemicals, with or without hemicellulases.

The removal of chlorophenolic compounds from kraft mill effluents bleached with chlorine (cBKME) or chlorine plus hemicellulases (bBKME) was studied in reactors of aerobic treatment lagoons. In these laboratory models, a stable microbial population removed biochemical oxygen demand at similar rates of the mill lagoon. Complete removal of nine chlorophenols and chloroguaiacols during microbial treatment of these effluents was detected by gas chromatography. Abiotic removal was only observed with 2,4-dichlorophenol and 2,4,5-trichlorophenol. There were no significant differences in degradative ability between microorganisms acclimated to grow in reactors fed with cBKME or bBKME. The latter had a lower content of adsorbable organic halogen and chlorophenols than cBKME. Microorganisms acclimated to cBKME or bBKME were only able to grow on phenol or guaiacol as sole carbon source. However, these microorganisms removed (0.1-0.5 mM) 4-chlorophenol, 2,4-dichlorophenol and 2,4-dichlorophenoxyacetate with BKME as primary carbon source. Under these conditions, 2,4,6- and 2,4,5-trichlorophenol, 4,5-dichloroguaiacol, 4,5,6-trichloroguaiacol and tetrachloroguaiacol were not removed. These results suggest that the microbial removal of bleaching chlorophenols and chloroguaiacols during aerobic treatment, probably takes place only because of their very low concentration (1-200 ppb) in BKME.

Species differences in the intracellular distribution of ciprofibroyl-CoA hydrolase. Implications for peroxisome proliferation.

Peroxisomal proliferators (HPP), such as ciprofibrate and clofibric acid, are species-specific drugs. Since HPP-coenzyme A derivatives might be involved in their action, we studied the subcellular distribution of liver ciprofibroyl-CoA hydrolase in rat and in two HPP-unresponsive species, humans and guinea pig. Total activity was similar in the three species and was not induced by clofibric acid treatment. In guinea pig, as in humans, the enzyme is localized in the mitochondrial and soluble fractions and no changes are observed after drug treatment. In the rat, the enzyme has a microsomal localization, but upon clofibric acid treatment it changes to a mitochondrial and soluble distribution, as in unresponsive species. These results raise the possibility that drug-induced hydrolases in rats might be normally expressed in humans and guinea pigs.

Saturable binding sites for the coenzyme A ester of nafenopin, a peroxisome proliferator, in rat liver cytosol.

1. At least three different molecular weight binding sites exist in rat liver cytosol for nafenopin-CoA, the coenzyme A ester and metabolic product of the carcinogenic peroxisome proliferator nafenopin. No binding sites for the free drug were observed. 2. Polypeptides of 35-40 kDa molecular weight range where no acyl-CoA binding proteins have been previously described bind the highest proportion of nafenopin-CoA (60-70%). Binding is displaceable by the CoA esters of other peroxisome proliferators (ciprofibrate and tibric acid) and also by oleoyl-CoA but by palmitoyl-CoA. Direct binding studies show that 35-40-kDa polypeptides bind oleoyl-CoA but not oleic or palmitic acid, or palmitoyl-CoA. 3. Polypeptides of 10-14 and 65-70 kDa also bind nafenopin-CoA. However, in contrast with 35-40-kDa polypeptides they also bind oleic and palmitic acid as well as their correspondent acyl-CoA thioesters.

[Campaigns against AIDS in Mexico: the sounds of silence or a bridge over troubled waters?]. / Las campañas contra el SIDA en México: los sonidos del silencio o puente sobre aguas turbulentas?

This paper analyzes the mass media campaigns developed by the Mexican Council for AIDS Control and Prevention (CONASIDA) from 1987 to 1994. This paper presents the lessons learned, a discussion of obstacles and mistakes, and the different evaluation methods which have been used in CONASIDA'S mass media communication strategies and their results. Knowing the opinion of some clue informants was considered relevant--taking into account that evaluations were made by and at CONASIDA--and seven in-depth interviews were conducted among intellectuals, non-governmental organizations (NGO) leaders and public opinion leaders. The importance of society's involvement in AIDS prevention is stated, and two examples of mass media campaigns developed by civil groups are commented. A section about the importance of research as a requisite to produce preventive messages is included, along with some examples. Finally, some conclusions are presented, useful to us, as well as others, in developing new educational campaigns.

Changing physician prescribing patterns: evaluation of an educational strategy for acute diarrhea in Mexico City.

This paper presents the results of an intervention strategy designed to decrease drug prescription and increase the use of oral rehydration therapy (ORT) in the treatment of acute diarrhea aimed at family medicine practitioners in two primary health care units of the Mexican Social Security Institute. The intervention consisted of six successive stages: 1) Baseline study of prescribing practices by all 69 physicians in both clinics; 2) Training workshop attended by 36 physicians, including a critical analysis of relevant up-to-date literature, review of results of stage I, discussion of a previously designed treatment algorithm for acute diarrhea, and modification of it according to participant's experience; 3) Post-workshop evaluation; 4) Establishment of a peer review committee to discuss the treatment behavior of participating physicians; 5) Mid-term evaluation for 2 months after the committee stopped functioning; 6) Long-term evaluation at 6, 12 and 18 months, of 20 physicians who received the complete intervention (study group) and 20 physicians who received none (control group). The treatment behaviors of the study and control groups were similar on baseline, but differed significantly (P < 0.01) in the post-workshop evaluation. The study group showed a reduction in the use of antibiotics (from 78.8% to 39.3%) and restrictive diets (47.3% to 12.4%), and increased the use of ORT (31.4% to 58.4%) for children younger than 5 years old with acute diarrhea. In the mid-term evaluation, the use of antibiotics by the study group decreased to 27.6%, prescription of restrictive diets decreased to 6.4%, and use of ORT increased to 73.8% (P < 0.01, in all cases). In the long-term evaluation, persistent positive prescribing behavior was still present in the study group, with a significant difference (P < 0.05) compared to the control group, where no modification was found in the prescribing behavior throughout the study. The average proportion of cases treated according to the algorithm by the study group increased in 29.2% (31.3 to 60.5%) after the workshop, and 45.2% (31.3 to 76.5%) after peer review committee. This behavior was maintained during 18 months after the intervention (74%). The control group showed no significant modification in the average proportion of cases treated according to the algorithm during the study (2 years 7 months). The active participation of physicians in the workshop and in the peer review committee was identified as the key to the short and long-term success of the educational strategy.