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Biomedical subjects

M V José

Publications and source records attributed to M V José.

At least 19 recordsLinked to original sources
PubMed2002

Analysis of bilateral inverse symmetry in whole bacterial chromosomes.

The positions of the 64 DNA tri-nucleotides (triplets) along the Borrelia burgdorferi chromosome were determined and cumulative position plots (CPP) were obtained. Analysis of CPP for complementary triplets revealed close correlations in complementary triplet frequencies (CTF) between opposing leading and lagging strands. Such bilateral inverse symmetry (BIS) applied also to complementary mono- and di-nucleotides and to some >3 n-tuples. At the level of individual bases BIS explains Chargaff's second parity rule for whole bacterial chromosomes. Using shuffled control sequences we show that single-base BIS was not the source of higher-order BIS. Analysis of CTF in 45 other chromosomes suggests that BIS is a general property of eubacteria. BIS at the various levels may be due to the very similar numbers of codons used in chromosomal halves. Evolutionarily, BIS could have resulted from asymmetric substitution of bases combined with genetic rearrangements. However, the provocative theoretical alternative of whole-genome inverse duplication is here considered.

Borrelia burgdorferi↗
PubMed2001

Inhibitory role of antibodies in the development of Taenia solium and Taenia crassiceps toward reproductive and pathogenic stages.

Untreated Taenia solium cysticerci obtained from different naturally infected pigs vary notably in their capacity to develop into intestinal tapeworms in prednisolone-treated hamsters, whereas cells derived from Taenia crassiceps cysticerci after 2 mo of infection almost always develop to cysticerci in the peritoneal cavity of susceptible BALB/cAnN mice. Preincubation of whole cysticerci or parasite cells with mice immunoglobulins raised against an 18-mer peptide epitope (GK-1) common to both parasites significantly interferes with both transformations. These crippling effects of antiparasite antibodies suggest new forms of immunological interference with parasite biology other than simple killing. Antibodies that cripple biological functions of the parasite, e.g., their development to reproductive or pathogenic stages, make them important protagonists in taeniasis/cysticercosis disease as classic parasitocidal antibodies. Different serum levels of crippling antibodies in the infected pigs could be responsible for the varied ability of cysticerci to convert to tapeworms. Antigens capable of inducing crippling antibodies, e.g., GK-1, could be useful as a therapeutic vaccine for pigs in order to reduce parasite transmission.

Animals↗
PubMed2000

Vaccination against Taenia solium cysticercosis in underfed rustic pigs of México: roles of age, genetic background and antibody response.

Vaccination of pigs of mixed genetic make-up, raised as rustically as done in rural Mexico, resulted in effective protection to experimental challenge against Taenia solium cysticercosis. Maximum protection was achieved if pigs were immunized at 70 days of age. There was large variation of viable parasite load within vaccinated pigs and controls, which is suggestive of significant genetic factors influencing susceptibility, besides immunization. Our results strengthen the advisability of pig vaccination for control of T. solium cysticercosis, since it lowers the number of viable cysticerci capable of transforming into tapeworms.

Age Factors↗
PubMed2000

Human tumor growth is inhibited by a vaccinia virus carrying the E2 gene of bovine papillomavirus.

BACKGROUND: Papillomavirus is the etiologic agent associated with cervical carcinoma. The papilloma E2 protein is able to regulate negatively the expression of E6 and E7 papilloma oncoproteins. Therefore, a new, highly attenuated vaccinia virus known as modified vaccinia virus Ankara (MVA), which carries the papillomavirus E2 gene, was used for the treatment of tumors associated with human papillomavirus. METHODS: Analysis of expression of the E2 gene from the recombinant vaccinia virus was performed by reverse transcription-polymerase chain reaction of RNA isolated from infected cells. Detection of the E2 protein was done by immunoprecipitation from proteins labeled with [(35)S]-methionine, isolated from infected cells. The therapeutic effect of the MVA E2 recombinant virus over human tumors was tested in nude mice bearing tumors generated by inoculation of HeLa cells. Series of 10 nude mice with tumors of different sizes were injected with MVA, MVA E2, or phosphate-buffered saline. Tumor size was monitored every week to assess growth. RESULTS: The MVA E2 recombinant virus efficiently expressed the E2 protein in BS-C-1 cells. This protein was able to repress, in vivo, the papillomavirus P105 promoter, which controls the expression of the E6 and E7 oncoproteins. In nude mice the MVA E2 virus reduced tumor growth very efficiently. In contrast, tumors continued to grow in mice treated with MVA or PBS. The life expectancy of MVA E2-treated mice was also increased three- to fourfold compared with that of animals that received MVA or PBS. CONCLUSIONS: The growth of human tumors was efficiently inhibited by the MVA E2 recombinant vaccinia virus. The absence of side effects in treated animals suggested that the MVA E2 virus is a safe biologic agent that could in the future be used in humans for the treatment of cervical carcinoma.

3T3 Cells↗
PubMed1998

Limitations of current diagnostic procedures for the diagnosis of Taenia solium cysticercosis in rural pigs.

The aim of the present study was to evaluate diagnostic procedures for porcine cysticercosis. Sera were obtained from 32 pigs reared in commercial farms, 47 pigs before and after experimental infection, 42 carefully necropsied rural pigs and 191 slaughtered pigs from rural communities in which the presence of the Taenia solium metacestode was assessed by tongue dissection. Sera were analyzed by ELISA to detect antibodies against T. solium antigens and to detect parasite antigens. Most sera from the necropsied rural pigs were also evaluated by the Western blot method. Antigen and antibody ELISA detection assays showed high sensitivity and specificity when applied to sera from pigs reared in commercial farms. In contrast, all methods (Ag-ELISA, Ab-ELISA assays, EITB and tongue inspection) showed lower sensitivity and specificity when applied to the generally lightly infected rurally reared pigs. The probability distribution of cysts in carcasses were also determined. These results emphasize the difficulties in detecting cysticercosis in rural pigs with low levels of cyst burdens.

Animals↗
PubMed1998

Randomised trial of albendazole and pyrantel in symptomless trichuriasis in children.

BACKGROUND: We aimed to find out whether symptomless infection with Trichuris trichiura is associated with impairment of growth and to assess the effect of a multiple-doses regimen of anthelmintic drugs on the growth of children. METHODS: In a community based trial, 622 Mexican children were randomly allocated one of three treatment regimens: 3 days of albendazole 400 mg daily (high efficacy); one dose of albendazole 400 mg (moderate efficacy); one dose of pyrantel (pyrantel embonate) 11 mg/kg (low efficacy). Growth was monitored for 12 months. Analyses were by intention to treat. FINDINGS: 113 (18%) children were lost to follow-up--34 from the pyrantel group, 45 from the albendazole 400 mg group, and 34 from the albendazole 1200 mg group. Among the 127 children with heavy pretreatment infections, albendazole 1200 mg was better than pyrantel in terms of an increase in arm circumference (mean 0.26 cm, p=0.044). Among the 381 children with low pretreatment levels of infection, changes in weight (mean difference between groups -0.33 kg, p=0.036), arm circumference (-0.18 cm, p=0.0095), and thickness of triceps skinfold (-0.41 mm, p=0.0031) were less in children on albendazole 1200 mg than in those on pyrantel. INTERPRETATION: Symptomless trichuriasis impairs growth and albendazole or pyrantel may affect growth, independently of a therapeutic action on parasites. Possible toxic effects of high-dose albendazole require further investigation.

Albendazole↗
PubMed1998

Probability distributions of thermodynamic affinities for heterogeneous receptor populations.

A statistical approach to characterize the thermodynamic affinity distributions of heterogeneous receptor populations in terms of stoichiometric binding constants is presented. The use of stoichiometric density distributions provides a novel description of ligand binding systems. The distributions of stoichiometric constants, Ti(Ki)'s, are obtained assuming that the distribution of site constants N(k) is known. It is found that in the case of heterogeneous systems with multivalent receptors, N(k) is an average over all the Ti(Ki)'s even when there are positive or negative site-site interactions. It is seen that in the absence or in the presence of site-site interactions the mean and the variance of the Ki's can be derived from a Scatchard plot. Some of these results are particularly applicable to bivalent heterogeneous antibody populations and other results are applicable to bivalent heterogeneous systems with different binding sites.

Antigen-Antibody Reactions↗
PubMed1997

Prevalence of infection, mean worm burden and degree of worm aggregation as determinants of prevalence of disease due to intestinal helminths.

Theoretical predictions of disease prevalence due to helminth infections based upon a simple probabilistic model which considers the infection prevalence, the mean worm burden and the degree of worm aggregation are presented. A numerical reappraisal of the likely estimates of the degree of aggregation based upon maximum likelihood estimates of the negative binomial distribution is presented. The prevalence of disease shows a positive relationship with the mean worm burden. This association is hyperbolic when helminth parasites are severely aggregated but is s-shaped when helminth parasites tend to be overdispersed. The prevalence of disease decreases with the degree of worm aggregation when the values of the mean intensity are low; as the mean intensity increases this association becomes positive. The relationship between prevalence of disease and prevalence of infection is hyperbolic for severe degrees of parasite aggregation and is s-shaped for intermediate degrees of aggregation. However, if the mean intensity is low and the degree of aggregation is high there could be a negative relationship between the prevalence of disease and the prevalence of infection. The presence of disease due to helminth parasites is feasible for determined ranges of values of the infection prevalence, mean intensity and the degree of worm clumping.

Animals↗
PubMed1996

Oscillatory fluctuations in the incidence of rotavirus infections by serotypes 1, 2, 3, and 4.

The statistical evidence for regularity in the epidemic cycles of rotavirus infection for serotypes 1, 2, 3, and 4 was examined. Hospitalization longitudinal data of the monthly incidence of rotavirus infections from the city of Melbourne, Australia during 1977-1993 were used. Periodograms were used for exploring seasonal and longer-term cycles (interepidemic periods) of rotavirus infection. There was a satisfactory agreement between the interepidemic period estimated by means of periodograms with the one predicted by theoretical epidemiological studies. Thus, there is a clear evidence of a biennial peak in the epidemiology of rotavirus. Results of the study show an evidence of the likely existence of an interepidemic cycle of 4.6-5.2 years of duration. The finding of this interepidemic cycle was unexpected, and does not arise from the alternating incidence of the 4 serotypes since this peak appears in the periodogram of each serotype.

Australia↗
PubMed1994

Epidemiological model of diarrhoeal diseases and its application in prevention and control.

In this paper, a prototype epidemiological model of acute bacterial and viral diarrhoeal diseases occurring in young children is formulated. The model is able to mimic the observed epidemiological patterns of infantile diarrhoeal diseases associated mainly with enterotoxigenic Escherichia coli or with rotavirus. The proposed mathematical model predicts a plausible pattern of the serological profile of an enteric infection. According to computer simulation experiments (CSE) with this model, it is not necessary to develop an enteric vaccine conferring total and long-lasting immunity in order to achieve protection from diarrhoeal diseases in young children. Given a protective efficacy and a finite duration of vaccine-induced protection, the optimal immunization policy must be sought. Oral rehydration therapy (ORT) intervention has a clear effect in diminishing the number of individuals dying from diarrhoeal illness. The CSE also predict an apparent reduction in age-prevalence of diarrhoeal diseases by use of ORT.

Bacterial Vaccines↗
PubMed1989

On the solution of mathematical models of herd immunity in human helminth infections.

The general solution of the mathematical model of herd immunity to human helminth infections recently proposed by Anderson and May is obtained. The numerical solution of a more accurate biological model is indistinguishable from the corresponding exact solution of a more tractable mathematical model. Computer simulations of some particular cases of this model support the notion that both ecological and immunological factors determine the observed convex patterns of age-prevalence and age-intensity curves of human helminth infections.

Animals↗
PubMed1985

Ligand binding systems at equilibrium: specificity, heterogeneity, cross-reactivity, and site-site interactions.

The simplest ligand binding model that can account for systems which consist of heterogeneous receptors that show site-site interactions and can react with several types of ligands was presented. This model was based on the grand canonical partition function whose properties and potentialities for obtaining binding functions are briefly illustrated. A computer simulation of this model was carried out in order to examine the contributions of site-site interactions on the shape of binding isotherms and on specificity curves. The shape of the binding isotherms was shown to be independent regardless of whether the path of binding was considered. However, the shape of the specificity curves was strongly dependent on site-site interactions and on the particular sequence of ligand-receptor configurations formed during the ligand binding process, leading to the conclusion that site-site interactions may influence the specificity of a system more than even very strong cross-reactions. A method based on the Ising model of statistical mechanics was also described and was used for obtaining binding functions applicable to infinite lattices which show site-site interactions and competitive binding. The results presented here point out possible errors that can arise if standard statistical methods are used to fit binding data in order to prove a given binding model.

Binding Sites↗
PubMedDate not supplied

[Epidemiology of rubella in Mexico].

An analysis of the transmission dynamics of rubella in Mexico based upon notified cases during 1983-1990 is presented. It is observed, for the first time, that the force of infection in the age-group of 15-44 years old and the average age of the infection at the national level show a slight increase simultaneously. The theoretical estimates of the interepidemic period coincide with the observed ones. The annual proportion of susceptible individuals is practically constant during 1983-1990. The intrinsic reproductive rate of rubella at national level and for the different age-groups is assessed. The annual estimates of Ro are small and they are practically unchanged for all age-groups, excepting the group of 15-44 years. The herd immunity of rubella for the different age-groups is evaluated and it is concluded that the best strategy for preventing congenital rubella in Mexico is to continue with the no vaccination policy against rubella. Nonetheless, the continuous monitoring of this policy is necessary.

Adolescent↗
PubMedDate not supplied

[Seroepidemiology of rubella in Mexico: data and theory].

The pattern of seropositivity of rubella obtained through the National Seroepidemiological Survey (NSS) of 1987-1988 is compared with the observed annual patterns of morbidity and with theoretical serological profiles based upon the age-distribution of cases. In spite of a lack of direct correspondence among the NSS results and the ones obtained from morbidity data, a relationship among the patterns and trends is observed. The theoretical methods used for inferring the proportion of seropositives as a function of age provide an inexpensive and fast alternative in order to monitor the current policy of no vaccination against rubella in Mexico.

Adolescent↗
PubMedDate not supplied

[Regionalization of Mexico based on primary health care indicators proposed by the WHO].

In order to carry out this work, the following questions were made: how has the development of the coverage of Primary Health Care (PHC) for each entity of the Mexican Republic been? has it been homogeneous? If heterogeneous, which states show similar development? and, which are the indicators of PHC that account for these differences? A statistical multimodal analysis known as Cluster analysis, based upon the PHC indicators recommended by the World Health Organization (WHO) in 1985, was carried out in order to answer the questions above made. One of the main results of this work was to identify clearly that there are important inequities among the different federal agencies regarding coverage. These differences indicate that the coverage of PHC in México has been polarized.

Delivery of Health Care↗
PubMedDate not supplied

[Composite indicators for primary health care. The case of Mexico].

In 1978 the World Health Organization proposed as a goal the following slogan: "Health for everyone in the 2000 year". Though, to obtain the covering first assistance indicators is crucial for the evaluation work and for the analysis of the health strategies. In 1981 the World Health Organization proposed 13 indicators, based on them, this work builds up three new indicators. These indicators allow to have a simple and reliable description of the covering that each one of the federal entities of the Mexican Republic keep. The 1985 WHO indicator, PROM, and our mixed indicator, Institutional Medical Assistance Request, are highly correlated. The Mixed indicators of Health Covering allow the making of global covering evaluations. Also allows the studding of all the covering relations and correlations reached with other indicators or variables.

Health Status Indicators↗
PubMedDate not supplied

[Universal history of mortality].

The history of human disease has to be based almost entirely on what we know about the changes in mortality and life expectancy; illness and suffering do not lend themselves to hard statistics, whereas births and deaths can be counted. To learn about the way diseases have been conquered in the past we have, therefore, to look at mortality. From this study we see that the major lethal diseases were conquered not so much by discovering how to treat them as by prevention. The decline on mortality began at the start of the past century, at a time of revolution and reform, and was greatly accelerated when the causes of many diseases were discovered at the end of the nineteenth century. Even in the twentieth century, the greatest improvements are still being achieved by preventive measurements.

Adolescent↗