X chromosome monosomy in primary and overlapping autoimmune diseases.

Female predominance is a common characteristic for autoimmune diseases attributed to the combined effect of hormonal influence and genetic factors. Since X chromosome has immunologically important genes, the age related X chromosome loss could contribute to the development of autoimmunity. X chromosome monosomy (XCM) has been associated with primary biliary cirrhosis (PBC) and systemic sclerosis. Herein, using fluorescence in situ hybridization (FISH) with specific centromeric probes, we report the rate of XCM in interphase nuclei in women with Reynolds syndrome (RS), an overlapping condition of PBC and systemic sclerosis (SSc). Frequency of nuclei with XCM was 12.1% (CI 95%, 8.5-17.1) in RS, 10% (7.1-13.9) in PBC, 9.2% (6.0-13.9) in SSc and 6.4% (5.1-8) in age-matched healthy controls. We found a significantly higher XCM frequency in RS PBC and SSc groups of patients when compared with controls, p<0.01, p<0.05 and p<0.05 respectively. XCM was highest in the RS group but not statistically different from PBC and SSc patients. Fetal-maternal microchimerism prevalence evaluated by Q-PCR for SRY sequences varies among groups, although no statistical differences were observed. Besides the above, we found an apparently important additive effect (89.1%) of PBC and SSc on the prevalence of XCM cells in RS patients. Another interesting finding was that the prevalence of XCM cells seems not to be dependent on the time of evolution of the AID studied. Moreover, the shorter time of evolution and the higher prevalence of XCM interphase nuclei observed in RS patients sustain our hypothesis of the additive effect abovementioned.

[Risk factors related to allergic diseases at Mexico City]. / Factores de riesgo relacionados con enfermedades alérgicas en la Ciudad de México.

BACKGROUND: Several studies suggest that the prevalence of allergic diseases has been increasing worldwide in recent years; then it is very important to identify some risk factors that could be related. OBJECTIVE: To know some hereditary and environmental risk factors that could be related to the development of allergic diseases in open population from Mexico City. PATIENTS AND METHOD: It was an open-population, cross-sectional trial, in two phases with a random sample size of 4272 individuals in 214 public health centers. A questionnaire was applied by health workers. Statistical analysis was made with Excel 97-2004 using the Mann-Whitney U test for continuous variables and chi-square-test for discrete variables. p < 0.001 was considered statistically significant. RESULTS: The prevalence of allergic diseases in Mexico City was 42.6%, allergic rhinitis was the most frequent. The most important risk factors for allergic diseases were: family history of atopy in first and second degree; early consumption of cow's milk; early weaning with cereal, egg, beef, fish and pulses; living with some animals, indoor plants, active and passive smoking, to keep stuffed toys in the rooms, as well as living in dwellings with dust, cold temperatures, wall saltpeter and with dampness (mold growth). CONCLUSION: Because genetic factors can not be modified, it is important to identify environmental factors related to the development of allergic diseases in order to promote preventive measures.

[Prevalence of allergic diseases in Mexico City]. / Prevalencia de las enfermedades alérgicas en la Ciudad de México.

BACKGROUND: There is a considerable variation in the prevalence of allergic disorders in developing countries. These differences may be attributable to different methodological problems and to the lack of operational definitions. Several studies suggest that the prevalence of allergic diseases has been increasing worldwide in recent years. However, in Mexico, there is no data in open population. OBJECTIVE: To know in open population the prevalence of allergic diseases in the counties of Mexico City, the frequence of symptoms in each allergic disease, the therapeutic modalities that patients seek, the school and work annual absences and the amount of money that each patient spends in antiallergic drugs. PATIENTS AND METHODS: It was an open-population, cross-sectional trial, in two phases with a random sample size of 8,000 individuals from 214 public health centers. Statistical analysis was made with Excel 97-2004: Mann-Whitney U test for continuous variables and chi-square-test for discrete variables, p < 0.05 was considered statistically significant. RESULTS: The prevalence of allergic diseases in Mexico City was 42.6%, allergic rhinitis was the most frequent. Children are the largest age group affected. The highest prevalence was found in Tlahuac county. Coexistence of allergic diseases was found in 19.9%. The 44.2% of allergic patients attended to their general practitioner. 20.4% of all patients spent 10-20% of their income in medicines and 26% do not have money to buy antiallergic drugs. School and work annual absences are 3.37 +/- 3.86 and 6.2 +/- 12.84 days, respectively. CONCLUSION: Allergic diseases must be considered a public-health problem in Mexico City.

Pore morphology and interconnectivity in a mesoporous/macroporous polyhedral silica foam material.

The pore system of a highly swollen, block-copolymer-templated, polyhedral silica foam material is investigated by a combination of transmission electron microscopy, nitrogen sorption, and NMR cryoporometry. The adsorption-desorption hysteresis and melting-freezing hysteresis data recorded by the respective methods provide pore volume and access channel sizes that virtually coincide for the two used methods. This provides a consistent picture where polyhedral foam cells of 60-70 nm diameter are interconnected by cylindrical access channels with several characteristic sizes for the latter.

Surface melting of octamethylcyclotetrasiloxane confined in controlled pore glasses: curvature effects observed by 1H NMR.

We have measured the thickness of the pre-molten surface layer that appears at the interface of octamethylcyclotetrasiloxane (OMCTS) to the matrix in controlled pore glasses with pore diameters ranging 7.5-73 nm. Except for the glass with the largest pores, the layer thickness data for different pore diameters fall on a single master curve when plotted versus Tm - T, where Tm is the size-dependent volume melting point of the pore-confined OMCTS. Hence, at a single temperature, the surface layer thickness depends strongly on the curvature of the pore wall and therefore that of the solid-liquid interface. For temperatures where it exceeds two monolayers, the layer thickness depends logarithmically on Tm - T; for the glass with the largest pores, this turns into a power law with the exponent -1/2. The results are interpreted in terms of a continuous model of the solid-liquid interface with an arbitrary curvature. Because OMCTS is a weakly polar molecule with close to spherical shape, our data also lend themselves to Lennard-Jones type simulations.

NMR cryoporometry with octamethylcyclotetrasiloxane as a probe liquid. Accessing large pores.

Octamethylcyclotetrasiloxane is presented and investigated as probe liquid for NMR cryoporometry or DSC-based thermoporometry. This compound which may imbibe into both hydrophilic and hydrophobic pores is shown to exhibit a melting point depression that is larger than that for other cryoporometric probe materials such as cyclohexane. The transverse relaxation time differs by more than three orders of magnitude between the solid and liquid states, separated by a sharp phase transition. Hence, as demonstrated in controlled pore glasses, octamethylcyclotetrasiloxane can provide pore size distributions for materials with pore sizes up to the micrometer range.

Maintenance of subcutaneous cavities with CO2.

UNLABELLED: Since mechanical retractors in endoscopic plastic surgery cause certain drawbacks, we developed a model in dogs, which, by insufflating CO2 into a subcutaneous cavity, we were able to maintain. We evaluated the magnitude of subcutaneous emphysema and absorption of CO2 by insufflating different pressures and the efficacy of external pressure on the skin with the purpose of limiting the subcutaneous emphysema. Sixteen dogs were divided in 3 groups, A, B, and C. We controlled the pulmonary function by using a volume-cycle ventilator. In all groups, we maintained a subcutaneous cavity by insufflating CO2. Groups A and C were insufflated at 15 mm Hg; group B, at 8 mm Hg. We placed circumferential Esmarch bandages on the thorax of groups B and C to delimit superiorly and inferiorly the surgical area. Arterial blood gas analyses (ABGA) were taken from the femoral artery 60 minutes after intubation, 60 minutes after Esmarch bandage was placed and at the end of the CO2 insufflation. Statistically, results were analyzed by Wilcoxon test. P < 0.05 was considered statistically significant. Group A showed extensive subcutaneous emphysema. Two dogs died. The systemic increase of the CO2 showed a median of 9.6 mm Hg (P < 0.05). In Group B, Esmarch bandages caused increase in CO2, with a median of 1.65 mm Hg (P < 0.028). None of these dogs showed subcutaneous emphysema during the insufflation after CO2 insufflation pressure augmented with a median of 3.7 mm Hg (P < 0.028). In Group C, chest restriction increased CO2 median of 6.1 mm Hg (P < 0.043), and subcutaneous emphysema shown was less extensive than group A. The CO2 increased after insufflation a median of 16 mm Hg (P < 0.043). CONCLUSIONS: Subcutaneous cavities can be maintained open with CO2 insufflation at 8 mm Hg, limiting perfectly the surgical area; as done with Esmarch bandages, it reduces CO2 absorption and makes this procedure safe.

Inorganic salt hydrates as cryoporometric probe materials to obtain pore size distribution.

The depression of the melting temperature of Zn(NO3)2.6H2O was used to obtain the pore size distributions in controlled pore glasses. Measured by 1H NMR, the average value of the temperature depression DeltaT and the known average pore size yield K=DeltaT.d approximately 116 K.nm as the material-dependent factor for Zn(NO3)2.6H2O in the Gibbs-Thompson equation. The melting temperature is close to room temperature. Hence, this salt hydrate and some related other ones are better materials than water (K approximately 50 K.nm) for cryoporometric studies of systems with hydrophilic pores. The data also provide 46 mN/m for the solid-liquid surface tension of this salt hydrate.

[Non-erosive gastroesophageal reflux disease. Incidence of clinical forms, characteristics of esophageal exposure to acid and symptomatic correlations]. / Enfermedad por reflujo gastroesofágico no erosiva. Frecuencia de sus variedades clínicas, características de la exposición esofágica al ácido y correlación sintomática.

BACKGROUND: It is estimated that up to 70% of community-based patients with heartburn have no evidence of esophageal mucosal injury or non-erosive gastroesophageal reflux disease (NERD). Studies in NERD patients using esophageal pH monitoring and symptom index (SI) have suggested different subgroups or clinical forms. OBJECTIVE: Our aim was to investigate frequency of different subgroups of patients with NERD according to esophageal pH-monitoring parameters and SI, and to determine esophageal acid exposure characteristics and the relationship between symptoms and acid reflux in NERD. MATERIAL AND METHODS: Patients with heartburn at least 3 times per week during 12 weeks during the last year and negative upper GI endoscopy were studied. All patients were submitted to 24 h esophageal pH-metry and SI was calculated. Patients were classified into three groups: group I, patients with abnormal pH-metry; group II, patients with normal pH-metry and positive SI (> or = 50%), and group III, patients with normal pH-metry and negative SI (< 50%). Total number of reflux episodes, length of episode, % time pH < 4, and Johnson-DeMeester score were evaluated. RESULTS: Three hundred patients, 206 women and 94 men, were included. A total of 137 (46%) were classified in group I, 62 (21%) in group II, and 101 (33%) in group III. There were no significant differences in gender and age among groups. All pH parameters were significantly higher in group I. In group II, there was good correlation between heartburn and acid reflux. Esophageal acid exposure in group III was minimal and there was no relationship among symptoms and acid reflux episodes. CONCLUSIONS: Subjects with NERD represent a heterogeneous group of patients. Three subgroups of patients with NERD were identified by pH-metry and SI; a) patients with abnormal acid exposure; b) patients with hypersensitive esophagus (heartburn with physiologic amounts of acid reflux), and c) patients with no correlation between symptoms and acid reflux.

[Variations in a 24-year period of colorectal and gastric cancer in Mexico]. / Variaciones en un periodo de 24 años del cáncer colorrectal y gástrico en México.

OBJECTIVE: Gastric cancer (CG) and colorectal cancer (CCR) are the two most common neoplasms of the digestive system in the world. We performed a study to determine incidence and relation between CG and CCR in five hospitals in Mexico City. METHODS: Patients with admitted diagnosis of CG and CCR at Hospital General de Mexico, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Hospital Español de México, Centro Médico Nacional "20 de Noviembre" from the Instituto de Salud y Seguridad Social para Trabajadores del Estado, and Hospital Central Militar from January 1978 to December 2001 were studied. RESULTS: A total of 7,136 patients were studied. (CG 3,830, CCR 3,306). At Instituto Nacional de Ciencias Médicas y Nutrición "Salvador Zubirán" CG was the most common digestive neoplasm; from 1999, ratio was inverted to < 1. At Hospital General de México, from the beginning and until 1984, ratio was > 2, and later had an average of 1.31. For Hospital Español, ratio always was < 1 without changes. At Centro Médico Nacional "20 de Noviembre", initially CCR was more frequent, then CG, and finally CCR. At Hospital Central Militar ratio was constant, > CG. At the beginning, was global behavior > CG, ratio seemed to invert, but since 1998 CG/CCR ratio was < 1 and continued that way. CONCLUSIONS: In this study, we found that changes of CG/CCR ratio in a period of 24 years showed elevation of CCR incidence at five Mexican hospitals.

[Assay validation for determining nitrites and nitrates in biological fluids]. / Valoración de un método para determinar nitritos y nitratos en muestras biológicas.

INTRODUCTION: Nitric oxide is an important modulator of numerous physiological and pathophysiological processes. An indirect form to detect NO production has been the quantification of its stable end products, nitrites and nitrates (NO2- + NO3-). These metabolites can be detected with a commercial kit, but it is somewhat expensive and not accessible to some laboratories in our country. OBJECTIVE: To validate an easy, accessible and less expensive assay for detecting nitrates and nitrites in biological fluids. MATERIAL AND METHODS: In this study we determined nitrates and nitrites by reducing nitrates enzymatically with nitrate reductase, followed by nitrites quantification using the Griess reagent. To validate the assay, NO3- concentration was evaluated in aliquots with known amounts of sodium nitrate, also NO2- + NO3- concentrations were detected in plasma containing known amounts of sodium nitrate, finally NO2- + NO3- levels were evaluated in plasma (n = 17) and ascites (n = 11) samples of cirrhotic patients. In samples of patients, NO2- + NO3- levels were also detected by using a commercial kit. RESULTS: The assay that we describe here detects nitrates in the range between 25 to 400 microM/L and nitrites between 25 to 100 microM/L. When specific concentrations of nitrates were added to plasma samples, the recovery percentage in most cases was greater than 95%. In plasma samples of cirrhotic patients, average concentrations of NO2- + NO3- was 44.6 +/- 22.4 microM (mean +/- SD), similar to that found using the commercial kit, 40.9 +/- 18.3 microM/L (p = 0.107). In ascitis samples, similar results using both methods were seen, 64.5 +/- 42.0 vs. 58.2 +/- 39.3 microM/L (p = 0.172) respectively. CONCLUSIONS: Our results suggest that the method described here could be considered as an alternative instead of commercial kits to determine NO2- + NO3- in plasma and ascites samples. In addition, this assay results more attractive because, it does not, require special equipment, it is very accessible to most laboratories, it may be use to assay one or more samples at any given time, but the most important advantage, is its cost effectiveness; thus each sample determination is about one fifth of the cost using the commercial kit.

Usefulness of cryohemolysis test in the diagnosis of hereditary spherocytosis

The clinical suspicion of hereditary spherocytosis (HS) must be confirmed at the clinical laboratory. The osotic fragility test (OFT) and the autohemolysis test (AHT) are the worlwide accepted assays to establish a definitive diagnosis of HS; however, they have some disadvantages. We describe herein our experience with the cryohemolysis test (CHT) as a tool to confirm the HS diagnosis. We included four groups of subjects, namely, patients with clinical HS, patients with mechanical heart valve prosthesis, malignant hematological diseases and healthy blood donors. CHT was carried out in all the groups, while OFT and AHT only in the HS patients and healthy individuals. OFT and AHT were performed according to previously described techniques. CHT was performed using red blood cells incubated in a hypertonic solution, preheated for 10 min and then tranferred to an ice bath for an additional 10 min. The resulting cryohemolysis was determined mesuring the free hemoglobin in the sample. There were no differences among the groups in terms of general characteristics. All HS suspicious patients had a positive OFT and AHT. CHT was positive in all patients from the HS group but in none of the subjects from the control groups (p<0.001). We found that CHT is a faster and easier-to-perform assay compared with OFT and AHT. Moreover, using CHT, the zone between normal and abnormal results is wider than OFT or AHT. We propose 0.7 to 11 percent hemolysis as reference values for CHT

Famotidina versus cimetidina en el tratamiento de la úlcera duodenal no complicada: estudio multicéntrico / Famotidine versus cimetidine in the treatment of uncomplicated duodenal ulcer: a multicenter study

La famotidina es un nuevo antagonista de receptores H2, con gran selectividad y afinidad para el sitio de enlace. Hipotéticamente, tiene mayor potencia y duración de efecto. Se llevó a cabo este estudio aleatorio y abierto, multicéntrico con el fin de evaluar la eficacia y seguridad de 40 mg de famotidina contra 800 mg de cimetidina, administrados como dosis única nocturna, en pacientes con úlcera duodenal no complicada. La respuesta al tratamiento se valoró endoscópicamente a las cuatro o seis semanas; se realizaron estudios clínicos y bioquímicos para evaluar la seguridad de la droga. Se estudiaron 90 sujetos, 47 recibieron famotidina y 43 cimetidina. A las cuatro semanas, las tasas de cicatrización fueron de 81% en el grupo con famotidina y 67% en el de cimetidina (P = 0.11). A las seis semanas los porcientes de cicatrización fueron de 98% y 88% respectivamente (P = 0.08). En los sujetos que no recibieron medicación anti-ulcerosa previa y/o en aquellos que tenían lesiones de > 1 cm, las tasas de cicatrización a las 4 semanas de tratamiento con famotidina fueron significativamente mayores (P < 0.05) a las obtenidas con cimetidina. El dolor diurno mejoró a la primera semana en el 93% y 83% de los pacientes que recibieron famotidina y cimetidina, respectivamente (P = 0.11); en cuanto al dolor nocturno, las tasas de mejoría fueron de 88% y 91% al cabo del mismo tiempo (P = 0.43). Se observaron efectos colaterales (atribuibles posiblemente a los fármacos) en seis pacientes (dos con famotidina y cuatro con cimetidina), todos ellos leves y reversibles una vez suspendido el trtatamiento. Los resultados sugieron que 40 mg de famotidina tienen utilidad y seguridad similares a 800 mg de cimetidina

Utilidad clínica de los criterios de Ranson en la evaluación pronóstica de los enfermos con pancreatitis aguda / Clinical utility of Ranson's criteria in prognostic evaluation of patients with acute pancreatitis

Con el fin de evaluar si los criterios de Ranson son útiles y aplicables en nuestro medio, revisamos los expedientes de 106 sujetos en quenes se estableció el diagnóstico de pancreatitis aguda (PA) durante el período comprendido de enero de 1975 a diciembre de 1984. Cuarenta fueron mujeres y 66 hombres. La edad varió entre 17 y 79 años (x ñ DE = 45,0 ñ 45.0 ñ 15.3 años). En cada caso se buscaron los once criterios descritos originalmente por Ranson y cols, y se anotaron el número de criterios posibles (aquellos que se buscaron y estaban anotados en los expedientes) y el de criterios presentes (los que existiendo fueron "positivos" de acuerdo a los parámetros del autor). Dos de los once (deshidrogenasa lácta y secuestro estimado de líquidos) fueron considerados como no evaluables. Sólo 15 de los enfermos (14%) tuvieron 10 criterios posibles. Los enfermos con PA grave mostraron una clara tendencia a presentar leucocitosis, hiperglicemia, hipocalcemia y elevación de urea. ªo hubieron diferencias significativas entre los otros parámetros evaluados. La morbilidad y mortalidad se incrementó proporcionalmente al número de signos presentes, pese a ello, encontramos una correlación directa ente el número de criterios posibles y el de criterios presentes, es decir entre mayor es el número de criterios buscados existe mayor posibilidad de encontrarlos alterados. Concluimos que los criterios de Ranson pueden ser útiles en la evaluación pronóstica de los enfermos com PA pero que su aplicación clínica en nuestro medio podría verse limitada por la disponibilidad en la obtención de todos los parámetros de laboratorio evaluados por este autor

Perfil de la investigación médica publicada en México: Un analisis de sus estrategias / Profile of clinical research published in Mexico: an analysis of its strategies

Con objeto de conocer los objetivos y las estrategias metodológicas empleados en la investigación médica publicada en México, se analizaron los trabajos, de cuatro revistas ampliamente conocidas y difundidas en nuestro medio: el Boletín Médico del Hospital Infantil de México, la Revista de Investigación Clínica, la Revista Médica del I.M.S.S. y Salud Pública de México. Durante el periodo estudiado se publicaron 161 artículos, de los cuales 75 (46%) fueron considerados elegibles para su análisis. Por su objetivo, predominaron las descripciones de cuadro clínico y/o evolución (29%) y evaluación de eficacia terapéutica (19%). Por su diseño, en su mayoría fueron observacionales, descriptivos, transversales, prolectivos y abiertos. Se concluye que la mayor parte de la investigación clínica publicada en México, por su objetivo, puede clasificarse en número pequeño de rubros y que en su elaboración con frecuencia se utilizan estrategias metodológicas débiles

La capacidad de crítica en investigación clínica en un grupo de residentes de medicina interna: I. El conocimiento práctico comparación entre el juicio apreciativo global y el razonamiento analitico / Critical appraisal ability of clinical research by a group of internal medicinal residents: I. Comparison of global appreciative judgmetn with analytical reasoning

Se investig'ó la capacida de crítica en investigación clínica en dos grupos: 47 residentes de medicina Interna (grupo experimental) y diez integrantes del personal administrativo (grupo control). El instrumento de medición se construyó con cinco trabajo de investigación resumidos, ya publicado o propuestos a consideración editorial, valido previamente a su aplicación que incluía dos aspectos: el juicio apreciativo global (JAG) y el razonamiento analítico (RA). Se encontraron diferencias altamente significativas en los resultados del JAG y el RA, entre el grupo experimental y el control. En ambos grupos se apreció una clara tendenia a sobreestimar la calidad de los trabajos valorados (JAG). En el grupo experimental se observó que el año académico (1§, 2§ ó 3§) no influyó significativamente en los resultados del JAG y el RA. No se encontró correlación significativa entre el JAG y el RA en ninguno de los dos grupos. Tomando como límite inferior a los resultados del grupo control, el desempeño del grupo experimental fue superior en el JAG con respecto al RA. Se concluye la importancia de explorar conductas (aprendizaje) relacionadas con la práctica (la capacidad de crítica en investigación clínica( ya que es la que a fin de cuentas, determina la forma en que se lleva a cabo ese gran conglomerado del saber y del hacer que es la investigación clínica

La capacidad crítica en investigación clínica en un grupo de residentes de medicina interna: II. Comparación del conocimiento teórico con el práctico / Critical appraisal ability of clinical research by a group of internal medicine residents: II. Comparison of the retical and practical knowñledge

Se estudió la capacidad de crítica en investigación clínica en los mismos grupos del estudio previo: 47 residentes de medicina interna y diez miembros del personal administrativo. En esta ocasión se exploró el conocimiento teórico: conjunto de conceptos y nociones relativos a la metodología de la investigación clínica (CT) a través de un instrumento que fue validado previamente a su aplicación. Se encontraron diferencias altamente significativas entre los dos grupos. El año académico no tuvo impacto apreciable en los resultados del grupo experimental. No se observó asociación significativa entre el CT por un lado y el juicio apreciativo global (JAG) y el razonamiento analítico (RA) por el otro, en ninuno de los dos grupos. Tomando como límite inferior a los resultados del grupo control, el desempaño del grupo experimental fue inferior en el conocimiento teórico con respecto al JAG y el RA. Se concluye que la teoría y la práctica (JAG y RA) de la capacidad de crítica en investigación clínica, son dominios diferentes por lo que no es válido afirmar que el conocimiento teórico sea equivalente al conocimiento práctico