Study of the diversity and short-chain fatty acids production by the bacterial community in overweight and obese Mexican children.

Obesity and overweight are health problems of multifactorial etiology, which may include changes in the microbiome. In Mexico, more than 30 % of the child population between 5 and 11 years of age suffer from being overweight or are obese, which makes it a public health issue in progress. The purpose of this work was to measure the short-chain fatty acid concentration by high-performance liquid chromatography (HPLC), and to characterize the bacterial diversity by ion torrent semiconductor sequencing, of 16S rDNA libraries prepared from stools collected from a sample of well-characterized Mexican children for normal weight, overweight, and obese conditions by anthropometric and biochemical criteria. We found that triglyceride levels are increased in overweight and obese children, who presented altered propionic and butyric acid concentrations in feces. In addition, although the colon microbiota did not show a clear bacterial dysbiosis among the three conditions, the abundance of some particular bacteria was changed with respect to normal controls. We conclude from our results that the imbalance in the abundance of at least nine different bacteria as well as altered short-chain fatty acid concentration in feces is associated to the overweight and obese conditions of Mexican children.

[Update of consensus recommendations of the Chilean Hypertension Society about ambulatory blood pressure monitoring]. / Actualización de las recomendaciones sobre el uso de la monitorización ambulatoria de presión arterial. Documento de consenso de la Sociedad Chilena de Hipertensión.

Ambulatory blood pressure monitoring (ABPM) is a valuable tool to evaluate the blood pressure pattern, to identify hypertensive patients, to diagnose white coat and masked hypertension and in situations in which a tight control of hypertension is crucial. This is an update of 1999 consensus recommendations about the use to ABPM, considering that there is new evidence concerning its benefits, and the clinical experience with its application has increased. Equipment programming, its installation, the interpretation and analysis of the data are described, and a report sheet for patients is included. New recommendations have been added to the accepted indications. Normal blood pressure ranges for children and pregnant women have been replaced by new data.

[Evaluation of a breakfast as screening test for the detection of gestational diabetes]. / Evaluación de un desayuno como prueba de tamiz para la detección de diabetes gestacional.

A standard breakfast was evaluated as a screening test (BT) for gestational diabetes in a case-control study. The breakfast had a high carbohydrate content and was designed based on women's preferences in a similar sample. Women were selected with a standard 50 g, 1 hour glucose screening test (GT). Fifteen women had a positive GT and 15 had a negative test. A glucose tolerance test (GTT) and a standard breakfast (719 kcal) were performed to all women. Age, weight, height, tricipital and subscapular skinfold thicknesses were obtained by previously standardized personnel and glucose levels were determined by an automatic technique (oxidase glucose). Ten women had gestational diabetes. Sensitivity and specificity were calculated for the GT and several values of the BT, in order to identify the threshold and optimum time. Concordance of both screening tests with GTT was calculated through Kappa test. For the BT, a sensitivity of 0.90 and specificity of 1.00 with a glucose level > or = 140 mg/L (7.2 mmol/L) at 60 and 90 minutes were found. The 60 minutes timing were preferred due to a shorter waiting time to performed the test. Concordance of GTT with GT and BT was 0.53 and 0.92 respectively, both statistically significant. GT had high frequency of false negative values (6/15) that explain the low kappa value. Standard breakfast can be used as an alternative method for assessing carbohydrate tolerance in pregnancy with a better physiological response in these women.

Association of Venezuelan equine encephalitis virus subtype IE with two equine epizootics in Mexico.

Two outbreaks of encephalitis consistent with an etiology of Venezuelan equine encephalitis (VEE) virus occurred in equines on the Pacific coast of southern Mexico in 1993 (Chiapas State) and in 1996 (Oaxaca State). In Chiapas, there were 125 cases, of which 63 were fatal and in Oaxaca, there were 32 cases and 12 fatalities. Virus was isolated from two horses from each outbreak, including three brain isolates and one from blood. Virus isolates (93-42124, ISET-Chi93, Oax131, and Oax142) were shown by indirect immunofluorescence, hemagglutination inhibition, monoclonal antibody ELISA, and nucleotide sequencing to be VEE virus, subtype IE, a type previously thought to be equine-avirulent. Genetic characterization and phylogenetic analysis indicated that the outbreak viruses were identical or nearly identical to one another and that they were closely related to equine-avirulent IE strains from Guatemala and the Gulf coast of Mexico. In a plaque-reduction neutralization test, sera collected from healthy horses in Chiapas and Oaxaca reacted significantly better with isolate 93-42124 than with Guatemala IE isolate 68U201, suggesting that subtle genetic changes may have resulted in alteration of neutralization domains. It is not clear whether these differences may also influence equine virulence. However, renewed VEE virus subtype IE activity in Mexico, and its apparent conversion to equine virulence, underscores the need for increased surveillance, additional laboratory and epidemiologic studies in VEE-endemic regions, and possibly new vaccines.

First reported outbreak of classical dengue fever at 1,700 meters above sea level in Guerrero State, Mexico, June 1988.

An outbreak of classical dengue fever occurred from March to August 1988 in the city of Taxco, Guerrero State, Mexico. Taxco is at an elevation of 1,700 meters above sea level, and this study represents the highest altitude at which an outbreak of dengue has been documented. An investigation was conducted to obtain serologic confirmation of dengue infection, determine the extent of the outbreak, and identify risk factors for dengue illness. Toxorhynchites cell lines were used for viral isolation, and hemagglutination inhibition was used to measure anti-dengue antibody titers. The case definition used in the investigation was any person with fever, headache, myalgias, and arthralgias, or rash or retroocular pain. Dengue virus type 1 was isolated from five acute cases. Of 1,686 persons living in the affected area, 42% (715) met the case definition. Large (200-liter) water containers were significantly associated with infection (relative risk = 1.7, 95% confidence interval 1.5-1.9). The effect of altitude on epidemic transmission is most likely modulated by seasonal temperatures. The epidemiologic and serologic confirmation of a dengue outbreak at 1,700 meters above sea level represents the capability of Aedes aegypti to adapt to new environments, and the potential for epidemic spread in cities at comparable altitudes or higher.

[Seroepidemiology of measles in Mexico]. / Seroepidemiología del sarampión en México.

Measles is an illness of universal distribution and great social impact. According to the WHO, the annual deaths due to this disease amount to more than a million children in the world. The objectives of this paper are to estimate the seroprevalence of titer of antibodies to measles in the population of 12 to 59 months of age in Mexico and identify the determinants of the immunity state. From the National Seroepidemiology Survey, 5,232 blood samples of children between 12 and 59 months of age, were analyzed, their blood samples were considered positive when the antibody titers were greater or equal to 1:4, tested by hemagglutination inhibition using sensitized erythrocytes. The National seroprevalence was 76.2 per cent. By age group, an increment in positive level was observed age increased. The seroprevalence was 56 per cent in children of 12 to 24 month and 82 per cent for children 48 to 59 month of age. The history of vaccination was obtained verbally; 62.5 per cent of seropositive didn't have vaccination history and 82.5 per cent were of those vaccinated were positive. By place of residence, at rural level (populations less than 2,500 inhabitants) 74 per cent positives, compared to 79 per cent in children of urban areas. All risk factor were significant, based on a univariate analysis, being the one with greatest risk those with negative vaccine history and children of one year of age. The efficiency of the vaccine estimation was of 63.6 per cent. Risk factors related to the vinculation of immunity protection to measles or seropositives were age, and verbal history of vaccination.

Immunization of six-month-old infants with different doses of Edmonston-Zagreb and Schwarz measles vaccines.

Because measles causes an estimated 2 million deaths per year among children in developing countries, including a substantial proportion of infants less than nine months old--the age at which vaccination is recommended--there has been interest in using different strains of vaccine and higher doses to achieve immunization of younger infants. We conducted a randomized trial of three different doses of Edmonston-Zagreb and of Schwarz measles vaccines in infants to evaluate the effect of the strain and dose of vaccine on the serologic response and acute adverse reactions to vaccination. Six-month-old infants received a standard, medium, or high dose of one of the vaccines, and nine-month-old infants received a standard dose. Antibody levels were measured before and after vaccination, by means of a plaque-reduction neutralization assay, in 1061 six-month-olds and 299 nine-month-olds. Edmonston-Zagreb vaccine produced higher rates of seroconversion and seropositivity than comparable doses of Schwarz vaccine. Among the six-month-old infants, the seroconversion rate 18 weeks after vaccination with the standard dose of Edmonston-Zagreb vaccine was 92 percent, that with the medium dose was 96 to 97 percent, and that with the high dose was 98 percent; the rates for the corresponding doses of Schwarz vaccine were 66 percent, 76 percent, and 91 percent, respectively. Higher seroconversion rates were observed with an increase in the dose of either Edmonston-Zagreb (P less than 0.01) or Schwarz (P less than 0.001) vaccine. The seroconversion rates produced by high and medium doses of Edmonston-Zagreb vaccine in six-month-olds were equal to or significantly higher than the rate produced by a standard dose of Schwarz vaccine in nine-month-olds (87 percent). Clinical adverse reactions were not associated with the strain or dose of a vaccine. We conclude that Edmonston-Zagreb vaccine is more immunogenic than Schwarz vaccine in infants and can induce effective immunization against measles at six months of age.

Dengue epidemics on the Pacific Coast of Mexico.

Dengue epidemics in three Mexican cities were investigated with retrospective surveys and virus isolations from acute cases. These epidemics were part of the continuing extension of dengue in Mexico since 1978 after 15 years without transmission. Serotype 1 dengue infection predominated in all epidemics, but in one city, type 2 strains were also isolated. The following findings were consistent in all three cities: 1) illness history provided evidence of presence of infection months before the epidemic became evident, 2) there was a very sharp and progressive increase of dengue illness attack rates by age, 3) there were no interpretable relationships between illness and the presence of different types of breeding sights in the home, 4) socioeconomic status was strongly negatively related to illness, and 5) geographical factors not related to the other measured variables had a strong effect on illness rates reflecting the focality of transmission. In addition, there was evidence of a strong protective effect against illness by the use of mosquito netting or the presence of screens on houses, but these relationships were not universal to all three cities.

[Etiology of suppurative otitis media in pediatrics]. / Etiología de la otitis media supurada en pediatría.

A study on the etiology of bacterial infectious processes of the middle ear in children was carried out in 50 patients with ages between 3 months and 12 years at two of the children's hospitals depending from the Federal District Department. Male infants were found to be preferably affected. In 46% of cases, Staphylococcus aureus was found; also, gram-negative germs appeared in 26%. Comments are made on the possible causes of the variants this report presents in relation with the literature on the etiology of otitis media in pediatrics. Stress is placed on the necessity to support antimicrobial treatment with cultures to determine the etiology of the process.

Seroepidemiologic studies in Oaxaca, Mexico. II. Survey for arbovirus antibody.

A serologic survey was conducted in south-western Mexico to obtain information on human experience with arbovirus infections. Sera were collected from two semitropical areas along the Pacific coast of Oaxaca State, two mountain areas above 1,700 meters and the interior valley at 1,500 meters. Of the 610 sera tested for group A antibody, 4.9 per cent were positive in the hemagglutination-inhibition (HI) test to Venezuelan (VE), 11 per cent to Eastern, and none to Western encephalitis viruses. In neutralization tests the antibody was shown to be probably due to VE virus infections. When sera were screened for group B antibodies in the HI test, 32 per cent were positive with St. Louis encephalitis (SLE), 19 per cent with Ilhéus, and 4 per cent with yellow fever viruses. The pattern of reactions suggested that SLE or an antigenically related virus was responsible for the antibody detected. An unusually high rate was found in a mountain area at 2,000 meters: 41 per cent of 113 persons tested were seropositive to SLE. Of 493 sera screened by complement-fixation test, 6 per cent were positive to Nepuyo, 4 per cent to Patois, and 3 per cent to Tlacotalpan viruses.

A comparitive study of virulences, plaque morphologies and antigenic characteristics of Venezuelan encephalitis virus strains

Virulences of VE virus strains from tropical regions of the North and South American continents were studied in adult Syrian hamsters, Swiss albino mice and cotton rats. Virulence profiles were based on frequency and time of illness and death following subcutaneous inoculation of small doses of virus as collected in nature or after only a few passages in laboratory hosts. Forty-one strains from Mexico, USA-Florida, Panama, Colombia, and Venezuela uniformity killed hamsters inoculated s.c. with 4-1000 PFU; incubation periods were usually 3-6 days, but some Panamanian and USA-Florida strains had incubation periods 1-2 days longer than strains from other countries. All of 37 strains from these countries regularly produced illness in adult mice, but killed only 71-82 percent; in adult cotton rats, signs of illness were not recognized, but death occurred in 18-30 percent. Variations in virulence profiles for mice and cotton rats among 28 Mexican strains were ogten as great as those seen among 9 strains from USA-Florida, Panama, Colombia and Venezuela. Virus strains from the Bush Bush areas of Trinidad, however, had distinctive virulence profiles. All 5 of these strains killed hamsters only after prolonged incubation periods of more than 5 days, and killed only 1 of 25 mice; neither of two strains killed cotton rats. Young and Johnson reported (Amer. J. Epid., 1969, 89 286-307) that these Trinidad strains should antigenically be classified as Mucambo rather than VE virus. The TC 83 attenuated strain of VE virus in a dose of 500 PFU given s.c. killed no hamsters, mice or cotton rats, but in some experiments employing larger doses, up to 20 percent hamsters became ill and 5-10 percent died without apparent relationship to dose. Plaque sizes and morophologies of 19 VE and 5 Trinidad Mucambo virus strains in primary chicken embryonic cell cultures did not correlate with virulence for hamsters, mice, cotton rats or man, nor with geographic, host or tissue source or year of collection. In sera of cotton rats and mice 3-4 weeks after s.c. inoculation, titers of VE virus HI antibody measured with hemagglutinin from a Mexican virus strain were similar for strains from Mexico, Colombia and Venezuela. However they were lower with USA-Florida and TC 83 virus strains and with Trinidad Mucambo virus strains, suggesting that these viruses differ antigenically from Mexican, Colombian and Venezuelan strains. Nevertheless the attenuated TC 83 vaccine virus protected adult mice against s.c. challenge by 28 Mexican and 8 other VE virus strains from USA-Florida, Panama, Colombia and Venezuela, suggesting that immunologically distinct types of VE virus based on cross-protection do not exist in these countries. (AU)