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Ceviche is a traditional dish made from raw fish meat marinated in lime juice without any heat cooking step throughout its preparation process. Although the use of organic acids as antibacterial agents is well known; recent research indicates that lime juice actually can reduce the risk of V. parahemolyticus infections but it is ineffective against other potential pathogens. Despite the fact that fresh fish meat is safe; exposed organs including skin, gills and guts represent a potential source of bacterial contamination. In Mexico, diarrheal diseases are caused mainly by contaminated food; it is estimated that almost 67% of infections are due the presence of bacterial agents mainly in frozen and fresh fish. The main objective of this study was to estimate the taxonomic diversity of microbial species present in ready-to-eat ceviche using a metagenomic approach. Six samples of commercially available ceviche were subjected to DNA high throughput sequencing and bioinformatics analyses, we identified between 65,000 and 131,000 reads per sample. The predominant phyla identified through the samples were Proteobacteria, Bacteroidetes and Firmicutes. We discuss the factors involved in the microbiological quality of this kind of raw foods and how they influence the bacterial diversity within the analyzed samples.

Self-expanding metallic stents (SEMS) are the ideal treatment for malignant gastric outlet obstruction (MGOO) in patients with a short life expectancy, but stent dysfunction is frequent. The primary aim of our study was to identify the predictive factors of SEMS dysfunction in MGOO and the secondary aim was to determine the technical success, clinical success, and nutritional impact after SEMS placement.A retrospective, longitudinal study was conducted at the gastrointestinal endoscopy department of the Instituto Nacional de Cancerología in Mexico City. Patients diagnosed with MGOO that underwent SEMS placement within the time frame of January 2015 to May 2018 were included. We utilized the gastric outlet obstruction scoring system (GOOSS) to determine clinical success and SEMS dysfunction.The study included 43 patients, technical success was 97.7% (n=42), and clinical success was 88.3% (n=38). SEMS dysfunction presented in 30.2% (n=13) of the patients, occurring in6 months after placement in 53.8% (n=7) of them. In the univariate analysis, the histologic subtype, diffuse gastric adenocarcinoma (p=0.02) and the use of uncovered SEMS (p=0.02) were the variables associated with dysfunction. Albumin levels and body mass index did not increase after SEMS placement. Medical follow-up was a mean 5.8 months (1-24 months).SEMS demonstrated adequate technical and clinical efficacy in the treatment of MGOO. SEMS dysfunction was frequent and diffuse type gastric cancer and uncovered SEMS appeared to be dysfunction predictors.

El efecto del ayuno ante-mortem en la calidad de carne de conejo ha sido poco estudiado. Se utilizaron 180 conejos machos de la raza Nueva Zelanda Blanca de 2,0 kg ± 0,04 de peso vivo (PV), los cuales fueron distribuidos en cuatro tratamientos (0, 4, 8 y 12 h de ayuno). Se utilizó un diseño completamente al azar, con el peso vivo al sacrificio como covariable. Se evaluaron las pérdidas de peso vivo (PV), el rendimiento de la canal, el pH inicial de la canal y final (24 h) de la carne. En el músculo Longissimus dorsi se evaluó el color, la capacidad de retención de agua (CRA), las pérdidas de cocción y la fuerza de corte. El PV disminuyó 0, 31, 54 y 76 g respecto al peso inicial, según el orden de los tratamientos. El rendimiento de la canal con 12 h de ayuno aumentó con respecto al testigo. El pH inicial fue mayor con 8 h respecto al resto de los tratamientos; sin embargo, el pH final fue menor con 12 h de ayuno con respecto al testigo. El color no se modificó por efecto de los tratamientos. La CRA disminuyó con 4 y 8 h de ayuno y la fuerza de corte se redujo con 8 h de ayuno, ambas respecto al testigo. Cuando se incrementó el tiempo de ayuno se reduce el peso de la víscera digestiva y urinaria e incrementa el rendimiento de la canal.

Mantle cell lymphoma is an aggressive subtype of B-cell non-Hodgkin lymphoma and its incidence is 0.5/100,000 inhabitants. Gastrointestinal involvement at diagnosis is 15-30%. The aim of our study was to analyze the clinical and endoscopic characteristics of mantle cell lymphoma affecting the digestive tract.A retrospective study was conducted, based on a case series of patients with mantle cell lymphoma affecting the gastrointestinal tract that were diagnosed over a 10-year period.Ten patients (11.7%) had gastrointestinal tract involvement. The upper endoscopic findings were polypoid lesions (66%), thickened folds (44%), and nonspecific changes in the mucosa (33%). At colonoscopy, polypoid lesions were viewed in 100% of the patients and ulcerated lesions in 40%.Polypoid lesions are the most common endoscopic characteristics in patients with mantle cell lymphoma of the gastrointestinal tract. Upper endoscopy and colonoscopy should be carried out on patients with mantle cell lymphoma, even those with nonspecific symptoms, to check their gastrointestinal status. Gastrointestinal involvement has an impact on disease staging.

Malignant dysphagia is difficulty swallowing resulting from esophageal obstruction due to cancer. The goal of palliative treatment is to reduce the dysphagia and improve oral dietary intake. Self-expandable metallic stents are the current treatment of choice, given that they enable the immediate restoration of oral intake. The aim of the present study was to describe the results of using totally covered and partially covered esophageal stents for palliating esophageal cancer.A retrospective study was conducted on patients with inoperable esophageal cancer treated with self-expandable metallic stents. The 2 groups formed were: group A, which consisted of patients with a fully covered self-expandable stent (SX-ELLAOf the 69-patient total, 50 were included in the study. Group A had 19 men and 2 women and their mean age was 63.6 years (range 41-84). Technical success was achieved in 100% (n=21) of the cases and clinical success in 90.4% (n=19). Group B had 24 men and 5 women and their mean age was 67.5 years (range 43-92). Technical success was achieved in 100% (n=29) of the cases and clinical success in 89.6% (n=26). Complications were similar in both groups (33.3 vs. 51.7%).There was no difference between the 2 types of stent for the palliative treatment of esophageal cancer with respect to technical success, clinical success, or complications.

The application of biological processes in restoring oil polluted sites is growing due to their efficiency in removing different classes of pollutants. The aim of this study was to determine the ability of microorganisms present in a drilling-waste polluted soil (36,200 mg TPH kg−1 soil) to remove weathered hydrocarbons under stimulated and non-stimulated soil conditions. The hypothesis under study was whether petroleum hydrocarbons removal could be enhanced by manipulating C/N ratio, water content and addition of three agroindustrial wastes. A Box-Behnken design was employed to evaluate the effect of each variable. Results demonstrated that, for orange peels and banana trunk treatments, the variable with the largest effect (p < 0.01) on hydrocarbon removal was the C/N ratio, indicating that higher ratio (100/3) improved removal (79.5–82%). The largest effect (p < 0.001) on hydrocarbon removal for pineapple wastes was observed with higher water content (60%) achieving the highest removal (89%). After 90 d...

The purpose of this paper is to develop a new methodology for analyzing astronomical data, in particular, one of the light curves obtained in the PHEMU campaign in 1997, where the mutual phenomena between Jupiter and its satellites were observed from the Earth due to the coincidence of the equatorial plane of Jupiter and the orbit plane of the Earth. The more specific aim of this study is to determine the times of the beginning and the end of the phenomena, and the moment when the recorded light flux was at a minimum. The techniques we applied were based on the wavelet theory, which allows us to study a signal from its approximations and details at different scales. Before applying the designed algorithm to our experimental data, we considered a synthetic light curve in order to check the reliability of our method. It should be mentioned that the results are not relevant from the astronomical point of view, since no corrections for albedo or illumination were applied to the recorded data.

Background: Laparoscopy is useful to treat surgical diseases, yet tying sutures in the cavity is a challenge. A knot to secure tissue approximation, which would be hand-made, secure, simple, easy, quick, reliable, and extracorporeal without extra mechanical devices, was developed and named the Gea knot. Methods: A comparative study of the Gea knot, the Roeder knot, and the classical surgical knot, as the gold standard, using polypropylene, silk, catgut, polyglycolic acid, and Polyglactin 910, all of them of 1-0 caliber, was performed in pigs. Measurements were time to perform, slippage, and breaking point which was measured with a manual digital tensiometer. Results: The Gea knot was significantly faster statistically to perform than the Roeder knot and more resistant against rupture and slippage. The slippage rate was significantly lower statistically in the Gea knot than in the Roeder knot when Polyglactin 910 and polypropylene were used. Conclusion: The Gea knot is a good alternative for laparoscopic procedures.

Salvinia minima is an aquatic fern which presents several advantages for the phytoremediation of wastewater. However, there is no information available for the operation of Salvinia-based systems (SBS) for nutrient removal from organic matter enriched wastewater. The objective of this work was to establish the optimum range of some key parameters for the operation of Salvinia minima ponds treating anaerobic effluents of coffee wastewater (AECWW). Batch cultures were performed outdoors, under subtropical conditions (Xalapa, Veracruz, Mexico). At the first stage, various pH levels were tested. After choosing the optimum pH, two pond depths were evaluated (0.10 m and 0.27 m). It was found that the productivity in AECWW was strongly affected by the pH, as it decreased with the increase in the pH. In fact, growth was completely inhibited at pH 8.0. In contrast, productivity at a pH of 6.0 and a pond depth of 0.27 m during the summer was equivalent to 27.92 ton/ha x year. The percentage of TKN removal increased with the pH value: 51 ′2.28% at pH 5.0; 78′1.47% at pH 6.0 and. 97 ′0.80% at pH 8.0. A similar situation was found for the case of NH 4 -N removal: (55 ′0.44%, 80 ′1.1%, 99 ′0.02%). The depth of the culture had influence on the productivity, protein content and nutrient removal. It was concluded that Salvinia minima is an adequate choice for the treatment and recovery of nutrients from AECWW. The pH for optimal operation of this type of pond was 6.0. The depth of the water column should be adjusted to 0.10 m for attaining a maximum relative removal efficiency (in terms of g NH 4 -nitrogen/l x d), although the productivity would not be at its maximum under these conditions. On the contrary, depth should be adjusted to 0.27 m for reaching the maximum absolute removal efficiency (considering the total volume of the reactor) and the maximum productivity. During the late autumn and winter period, the AECWW should be diluted 1:2 in order to enhance ammonia nitrogen removal.

The phylogenetic position of the subantarctic brown macroalga Desmarestia chordalis was inferred from nuclear ribosomal DNA internal transcribed spacer sequences, which were compared with published homologous sequences of putative relatives. According to the molecular data, D. chordalis is closely related to the Antarctic species D. menziesii, and more distantly related to other taxa of similar morphology, i.e. Antarctic D. anceps and northern hemisphere D. aculeata.

"El interés en el desarrollo y uso de empaques alimenticios a base de biomateriales ha venido creciendo debido en gran medida a la necesidad de reducir y sustituir el empleo de plásticos y envases sintéticos, por materiales menos agresivos con el medio ambiente. Además, estos materiales pueden actuar como barreras semipermeables preservando las características organolépticas de productos vegetales. En este sentido, en la presente investigación se elaboraron películas comestibles a base de gelatina y carboximetilcelulosa (CMC) estudiando el efecto del contenido de glicerol y pH en sus propiedades fisicoquímicas. Asimismo, se evaluó el efecto de las películas en la vida postcosecha de frutos de guayaba. La caracterización de las películas se realizó a través de la resistencia a la ruptura, coeficiente de difusión al vapor de agua y solubilidad en agua. Estas propiedades estuvieron en función del contenido de glicerol y el pH de la solución formadora de película. Los resultados indicaron que tanto la incorporación de glicerol como el pH influyeron de manera importante en las propiedades evaluadas. Los frutos recubiertos con películas de gelatina-CMC presentaron menores pérdidas de peso y menores pérdidas de firmeza en comparación con los frutos control, sin embargo, no se identificaron diferencias en °Brix."

Recent studies reported increased presence of Blastocystis in patients with Irritable Bowel Syndrome (IBS) and an etiologic role has been proposed. The pathogenic role of Blastocystis is controversial, because it is frequently found not only in individuals with enteric symptoms but also in healthy and asymptomatic subjects. Furthermore, there are few studies of blastocistosis in Mexico.To assess the frequency of Blastocystis sp. in IBS patients using molecular techniques and to describe its phylogenetic relationship with sequences of other countries.IBS patients according to Rome III criteria were enrolled. In all patients evaluations included: colonoscopies, coproparasitoscopic studies, coproculture, fecal virus screening. PCR and sequencing for Blastocystis sp. were also performed.We recruited 11 men and 51 women with a mean age of 45.6 (SD ± 15.7) years. Eighty-six percent of the IBS patients presented a normal colonoscopy, 8% showed polyps and 6% diverticular disease. Blastocystis sp. was identified in 25% patients (all of them with normal colonoscopy), while two patients had Endolimax nana and Entamoeba histolytica/E. dispar, respectively. Phylogenetic analysis showed that major sequences of Mexican carriers clustered together with sequences of parasites from Japan and Denmark; furthermore, two sequences from IBS patients were grouped in a single cluster.Blastocystis sp. was identified in 25% of the IBS patients. Our data support the hypothesis of clonal lineages in distinct geographical areas in the world.

Simulators have been used as a training method; they allow training, skill development, standardization of techniques and the performance of a greater number of risk-free procedures. Endoscopic submucosal dissection (ESD) is the standard treatment for early gastric cancer since it allows en bloc resection of larger lesions however requires longer procedure time and has more complications than endoscopic mucosal resection.To evaluate the use of biological inanimate simulators in endoscopic training for the development of skills required for ESD.Experimental design using a biological inanimate simulator to evaluate the development of endoscopic skills. Five trained endoscopists with knowledge of the ESD technique, but without previous experience were selected. Technical success, complication rate and procedure time were evaluated. Each participant performed a self-evaluation.18 lesions of 10-20 mm in diameter were dissected, with a mean area of 2.64 ± 2 cm2 and a mean procedure time of 21.08 ± 14.01 minutes (5.48 - 48.61). Self-evaluation and instructor's evaluation showed a strong positive correlation. There was no correlation between lesion size and procedure time. There was one perforation (5.8%), which was successfully managed with one endoclip. Complications such as bleeding could not be assed.The use of inanimate biological simulators allows training in complex endoscopic procedures such as ESD with a wide safety margin. Lesion size did not correlate with procedure time. It is necessary to increase the number of procedures to improve the learning curve. This simulator does not allow evaluation of complications other than perforations.

This paper presents a new numerical approach to the study of non-periodicity in signals, which can complement the maximal Lyapunov exponent method for determining chaos transitions of a given dynamical system. The proposed technique is based on the continuous wavelet transform and the wavelet multiresolution analysis. A new parameter, the \textit{scale index}, is introduced and interpreted as a measure of the degree of the signal's non-periodicity. This methodology is successfully applied to three classical dynamical systems: the Bonhoeffer-van der Pol oscillator, the logistic map, and the Henon map., 14 pages, 6 figures

We have applied wavelet techniques to analyze GPS time-series data from REGID geodetic network, deployed at Deception Island Volcano (South Shetland Islands, Antarctica). In the present analysis wavelets are used to detect periodic components and to filter the data. The high frequency components can be associated to the orbital period of the satellites and to local tidal effects, whereas the medium frequencies seem to be related to the weather cycle. The wavelet filtering procedure is based on the SURE estimator, and a considerable reduction in noise is achieved, particularly in the Up component, whose deviation is reduced down to the deviation of the horizontal components before the denoising. An estimation of the displacements in the network for the period 2001/02 – 2005/06 is also included.

Since 1987, Spain has been continuously developing several scientific projects, mainly based on Earth Sciences, in Geodesy, Geochemistry, Geology or Volcanology. The need of a geodetic reference frame when doing hydrographic and topographic mapping meant the organization of the earlier campaigns with the main goals of updating the existing cartography and of making new maps of the area. During this period of time, new techniques arose in Space Geodesy improving the classical methodology and making possible its applications to other different fields such as tectonic or volcanism. Spanish Antarctic Geodetic activities from the 1987–1988 to 2006–2007 campaigns are described as well as a geodetic and a levelling network are presented. The first network, RGAE, was designed and established to define a reference frame in the region formed by the South Shetlands Islands, the Bransfield Sea and the Antarctic Peninsula whereas the second one, REGID, was planned to control the volcanic activity in Deception Island. Finally, the horizontal and vertical deformation models are described too, as well as the strategy which has been followed when computing an experimental geoid.

Deception Island (62.93oS, 60.57oW) is one of the few active volcanoes in the Antarctica, whose most recent eruptions took place in 1842, 1967, 1969 and 1970.

Resumen La laparoscopia representa un nuevo abordaje para la cirugia urologica ofreciendo una serie de ventajas. Su aprendizaje es un aspecto fundamental. Para la instauracion en la practica diaria es necesario mucho entrenamiento. El tiempo empleado en la curva de aprendizaje sigue siendo realmente largo y las maneras de entrenamiento escasas. En la actualidad existen los modelos artesanales de simulacion, que son aparatos sencillos y de bajo costo, ademas que pueden ser utilizados en cualquier sitio, facilitando el entrenamiento. Hicimos una revision en la literatura reciente acerca de estos modelos artesanales, que pueden en mucho facilitar el inicio del aprendizaje laparoscopio.

The placement of intraabdominal polypropylene mesh entails risks of adhesions and fistulas that can be avoided by preperitoneal placement.This comparative, open, experimental, prospective, randomized, and transversal study randomized pigs into two groups of 11 each for intraperitoneal (IPOM) or preperitoneal (TAPP) polypropylene mesh placement by laparoscopy. Diagnostic laparoscopy and tissue en-bloc resection was performed 28 days postoperatively for histopathologic analysis.The following data were observed for the two study groups: surgical time (IPOM: 35.73 +/- 4.22 min; TAPP: 58.09 +/- 6.28 min; p = or0.0001); adhesions (IPOM: 81.81%; TAPP: 27.27%; p = 0.032), grade III for IPOM and grade II for TAPP (p = 0.001); and interloop adhesions (IPOM: 81.81%; TAPP: 9.09%; p = 0.003). No fistulas were found in either group. The TAPP procedure showed better integration of mesh, without lesion to abdominal organs. Two complications, occurred with IPOM, and one with TAPP (p = 1.0, not significant).The perperitoneal technique requires more time, but has fewer adhesions and less intraabdominal inflammatory response. It is a feasible technique that may diminish risks in the laparoscopic treatment of incisional hernias with polypropylene mesh.

The purpose of this work is to present the results of a bibliometric research conducted on AIDS in Africa, Southern. The literature production and communication patterns were analysed in an attempt to obtain indicators so as to support the decision making processes related to the prevention and control of AIDS. An Internet MEDLINE bibliographic search was conducted on AIDS and Africa, Southern for the period 1980-2001. The research was limited to studies conducted on humans; and indicators related to productivity, geographic distribution by country, language and subject content were identified.A total of 1.820 postings were retrieved and analysed. Main production was distributed among South Africa (42.36%), Zimbabwe (20.44%) and Zambia (19.90%). Most of the documents corresponded to articles published in scientific journals (55.33%). English was the main language used (97.75%); and the production in collaboration of two or more authors was significant (55.61%). The subject content of the research was related mainly to Health Education, Infant, and Sex Behaviour. A high production at the national level —mainly local universities— and the influence of USA and United Kingdom academic institutions was also found. A comparison with other geographic regions as well as the lines for further research actions are described. El propósito de este trabajo es el de presentar los resultados de un proyecto de investigación bibliométrica realizado sobre SIDA en la región del Sur de África. El estudio pretende identificar los mecanismos de producción y comunicación de la literatura existentes, en un esfuerzo por apoyar a los procesos de toma de decisiones relacionados con la prevención y el control del SIDA. Se realizó una investigación bibliográfica en MEDLINE sobre SIDA (AIDS) y el Sur de África (Africa Southern), para el período 1980-2001. La investigación se limitó a estudios realizados en seres humanos; y se buscaron indicadores relacionados con el tipo de producción, periodicidad anual, distribución geográfica por país, cobertura de idioma y temática.Se encontró un total de 1.820 registros. La producción mayor se registró para South Africa (42,36%), Zimbabwe (20,44%) y Zambia (19,90%). En su mayoría, la producción correspondió a artículos publicados en revistas científicas (55,33%); en idioma inglés (97,75%) y derivada de la colaboración de dos o más autores (55,61%). La cobertura temática se orientó a estudios sobre educación para la salud, investigaciones sobre infantes, y la conducta sexual. Se encontró un alto índice de producción nacional, principalmente de universidades locales; además de la influencia en la región de instituciones académicas de los Estados Unidos de Norteamérica y el Reino Unido. Se presentan comparaciones con los resultados obtenidos de otras regiones geográficas y se describen algunas líneas de investigación necesarias para continuar este tipo de análisis.

Tobacco consumption is a public health problem. Hospitals are not free of this circumstance because there are smokers inside these institutions; thus, it is important to identify who smoke in hospitals.A general survey with closed questions was carried out among 659 workers at a tertiary level general hospital. Smoking habit was positive in 184 employees and negative in 475. The majority of smokers were married and worked in the administrative offices, 46 of which belong to the medical area. Academic level was not an important determinant for tobacco consumption. The habit began between 10 to 20 years of age, mainly in relation with a sensation of pleasure, relaxation, and the need to smoke.The main site for smoking was the working area, 70% of nonsmokers are converted passive non-voluntary smokers. It is important to take actions to avoid tobacco smoking in hospitals in pursuit of a hospital environment free of tobacco smoke.

Maximum protein accumulation (71%, w/w) and nutrient removal by a mutant strain of Spirulina maxima growing on sea water supplemented with anaerobically treated pig slurry was achieved at 30°C with constant illumination (60 to 70 μEm(-2)s(-1)), using a flow rate of 14.5 cm s(-1) (20 rev. min(-1) of a paddle wheel). Total phosphates were decreased by 99% and all ammonia-N was removed under these conditions.

Information on nutritional status of the rural Mexican population is mostly obtained from cross-sectional studies. This investigation evaluates semi-longitudinally the nutritional level of a sample of the rural population of Mexico. A total of 15,552 individuals in 2,587 households from 208 rural communities were evaluated. Body weight and height of rural boys and girls were found to be significantly lower than in their urban counterparts. Severe forms of weight for age or height for age inadequacy were more frequent in females than in males, in smaller communities than in larger ones, and in economically depressed zones than in those with a good economy. Our data showed a lower frequency of mild and moderate forms of possible malnutrition than previous studies (20 vs 50%) using as a criterion weight for age. These differences are explained on the basis of sampling bias.The nutritional status of 15,552 individuals of both sexes in 2587 households from 208 rural communities in Mexico was evaluated in a semilongitudinal nationwide study. Research was carried out from March 1982 to February 1983. The communities were randomly selected from among the 3000 with Mexican Institute of Social Security-COPLAMAR primary health care services. The 8 geoeconomic zones identified by Bassols-Batalla were represented. 10 families with at least 1 infant under 1 year old were selected in communities with under 5000 inhabitants, while 20 such families were selected from communities with 5001-20,000 inhabitants. Body weight, height or length, and arm and calf circumferences were measured in all household members in March-April 1982, and again in July-August 1982 and January-February 1983. The proportion of household heads employed primarily in agriculture ranged from 88% in the smaller communities to 32% in the larger. Families in small communities were mainly peasants in subsistence farming, while household heads in larger communities who were employed in agriculture were mostly owners of small plots. 40-54% of the mothers in communities of different sizes had 3 years or less of school attendance. Comparison of growth curves of the rural population with reference data from urban children showed similar median body weight in both groups at 2 years of age. But by age 18, median weight and height, respectively, were 8.6 kg lower and 9 cm shorter for rural boys and 5.5 kg lower and 5 cm shorter for rural girls. The most severe forms of inadequacy in weight for age were more frequent in females than males, in smaller communities than larger, and in the economically depressed zones. Severe inadequacy of height for age was more frequent in the states located on the southern Pacific Coast and the Gulf of Mexico. The frequency of mild and moderate forms of malnutrition according to weight for age was 20%, lower than the rate of 50% estimated in previous published studies. Selection of a broader range of rural communities rather than just the most marginal, and the bias introduced by selecting the sample from among communities with primary health services may explain the lower rate in this study.

Survey among the workers of a general hospital to investigate how may of them smoke by means of a closed questionnaire given to 1092 Subjects. Smoking habit was positive in 678 (62.1%) and negative in 414 (37.9%); statistical difference was significant p 0.01. The rate for nocturnal workers was 80.0 in comparison with those of the morning and evening with 55.81 and 62.38 respectively. Men smokers had 66.79 of rate and women 57.55 with no statistical difference. Cigarette was the most common form of tobacco consumption, pipe and cigars were very rate. The most important number of smokers were 31-40 (65.4% and 21-30 (62.7%) years old, very few under 21 but among these 63% were smokers. Smoking habit was more common in the groups of high schooling [correction of scolarity]. Physicians were an important group of smokers, 61.6 per cent of 284 use to smoke while working in the hospital. Other characteristics of smokers are discussed and it is concluded that is necessary to take action to get a tobacco free hospital.

Three different methods to assess haemoglobin A2 concentration (microchromatography and cellulose acetate electrophoresis with further elution of the bands or measured by densitometry) were compared among them. A statistical significant difference (P less than 0.05) was found between densitometry and the other two methods. Microchromatography and the elution method showed no statistical difference between them. The most important technical aspects of each method as well as some possible error factors were also discussed.

The percutaneous, intrahepatic inoculation of E. histolytica trophozoites in weanling hamsters produced lesions of various shapes and sizes. The time-span between inoculation and sacrifice did not correlate with the size of the lesions. Histoenzymologic technics for acid and alkaline phosphatases, adenosinetriphosphatase (ATPase) and glucose-6-phosphate dehydrogenase (G-6-P DH) showed that the necrotic material is positive to the two former phosphatases whereas ATP-ase shows distorted bile canaliculi due to profound parenchymal alterations and the presence of G-06-P DH activity in parenchyma as well as its lack of activity in necrotic material suggests that the pentose cycle is involved in the genesis of the lesion. The presence of collagen fibers surrounding the lesions suggests that during the expansion of the lesions, there is a granulomatous inflammatory stage with fibrosis immediately followed by fibrinolysis. Four zones can be distinguished in an expanding lesion: necrosis, a zone of junction between necrosis and parenchyma which depicts a crown of invasive trophozoites surrounding the necrosis, a histiocytic halo and a zone of peripheral necrosis.

This paper shows the results of a study of acute diarrhoea (AD) in 137 rural communities in Mexico. We studied 51 communities with 1000 inhabitants or less, 45 communities with 1001 to 5000 inhabitants and, 41 with 5001 to 15000 inhabitants. All in all we observed 4,796.9 persons year during a period comprised from March 1982 to February 1983. In communities with more than 5000 inhabitants there occurred 0.85 episodes of AD per person-year, whereas in the smaller ones the incidence was only 0.58 episodes per person-year p less than 0.01). In small communities the frequency was higher in families with poor water supply and inadequate excreta disposal, whereas in large communities the frequency was not affected by such services. In 95.6 percent of the cases the episodes were self-limited within the first 14 days. There were seven deaths, five occurring in children under one year of age, six in children living in small communities and, five associated with dehydration. These results suggest that the size of the community constitutes a risk factor for AD in rural areas, which deserves to be explored in further studies. The lethality observed in small communities stresses the need of programs for better treatment of this frequent disease.

This study describes the epidemiology of acute respiratory infections (ARI) in a sample of rural population of México. The study includes 137 communities from all over the country: 51 with 5001 to 15000. In each community ten families with one child under one year of age were followed. Each family was child under one year of age were followed. Each family was visited weekly by one physician from the local IMSS-COPLAMAR clinic in order to register frequency and characteristics of ARI in each family member. We followed 1359 families and observed 4796.9 persons-year. Eight thousand and two episodes of ARI were observed. The relative risk of getting ARI in children below two years of age was 2.8 and in severe malnourished was 1.8. The frequency of ARI was higher in large communities than in small ones. Eight six point eight percent of the episodes were upper respiratory infections, 95.3 percent of the cases cured, 4.6 became chronic and there were four deaths. Mortality rate was 0.8 per 1000 persons-year. Sixty nine point eight percent of the cases received antithermics, 49.3 percent antihistaminics and, 48.6 percent antibiotics.