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To compare the histological, morphological and the biophysical measurements between hen and quail corneas, in order to determine which of them were better suited for use as an animal model for research into corneal refractive surgery.A study was performed using the biophysical measurements of the cornea (curvature, thickness, refraction, and axial length) of 20 animals (10 hens and 10 quails). The corneas were then prepared for histological analysis under microscopy light.The analysis showed that both groups have the same number of corneal layers as the human cornea and with an evident Bowman's layer. The thickness of the hen cornea and axial length of the eye, 225.3±18.4μm and 12.8±0.25mm, respectively, were larger than that of the quail (P.01 and P.001, respectively). The radius of curvature for the hen central cornea, 3.65±0.08mm, was greater than that for the quail (P.001), but the refractive power of each cornea was similar. The proportion of total corneal thickness of the hen stroma, 82.6%, was more similar to that of the human than was the quail stroma, 72.5%. Within the hen stroma, the density of keratocytes, 8.57±1.49 per 5,000μm(2), was about half that in the quail stroma (P.005).Because of the large size of the hen cornea, the stromal thickness and proportional similarity of the corneal layers with human cornea, the hen maybe better than the quail as an alternative species suitable for use in studies of corneal refractive surgery.

To measure the incidence rate and trend of acute leukemia (AL) in political districts of Mexico City.Descriptive longitudinal study conducted at six hospitals that care for nearly 97.5% of all cancer cases among children in Mexico City. Study data were collected in 1995 and 1996, and were analyzed in 1999, at the National Medical Center "Siglo XXI" Children's Hospital, of the Mexican Institute for Social Security. Calculations of acute leukemia annual incidence rates, standardized rates, and standardized morbidity rates (SMR) with 95% confidence intervals, were obtained for each district. Morbidity trends were assessed through average change rates.In this study we observed an increasing trend of acute lymphoblastic leukemia (ALL) incidence in five districts: Alvaro Obregon, Cuauhtemoc, Gustavo A. Madero, Iztacalco, and Venustiano Carranza. Acute myeloblastic leukemia (AML) showed no significantly statistic increase of incidence in any district. AML did show a significant SMR in Alvaro Obregon district (SMR = 2.91, 95% CI 1.63-4.80). Higher SMRs were found in the south and southwest areas of the city.Increasing incidence of ALL was observed in five districts of Mexico City. AML incidence was the highest in Alvaro Obregon district.

Elaborate and assess the degree of validity of a prognostic model for evaluating patients admitted to the Neonatal Intensive Care Unit (NICU).Cases and controls nested in a cohort.NICU of two tertiary hospitals and another second level hospital.The study was carried out in two phases. During the first phase (elaboration of a model), 336 newborns were studied; 112 belonged to the case group (dead patients) and 224 to the control group (live patients discharged). For the second phase (model validation), 300 patients were included that did not participate in the first phase, 100 cases and 200 controls.For each patient admitted to the study, clinical, paraclinical, perinatal and comorbidity factors were determined within the first 12 hours. Variables of statistical significance in the bivariate analysis were included in a logistic regression model with the objective of identifying a prognostic model.The variables that constituted the prognostic index were gestational age x birth weight, the paO2/FiO2 ratio x O2 saturation, arrest cardiac, major congenital malformations, septicemia and base excess. The model showed to have a sensitivity of 70% and a specificity of 91% during the elaboration cohort. In the validation cohort, sensitivity was 68% and specificity was 92%, a positive predictive value of 80%, negative predictive value of 85% and a correct classification rate was 84%.The Neonatal Mortality Prognostic Index (NMPI) developed in this study showed to be useful for the evaluation of hospital mortality for severely ill newborns admitted to NICU.

To assess satisfaction of attendants to a National Meeting on Medical Research in relation with the scientific quality and level of discussion of the research work.An anonymous self-applied questionnaire was handed out to gather opinions about the scientific quality, level of discussion of the research work, and overall satisfaction with the meeting. The studied population included 400 physicians, all of them authors or collaborators of the research work presented.The rate of response was 62% (n = 249). Two hundred and twenty-four approved the scientific quality (90%), and 203 were satisfied with the level of discussion of research (88%); 239 were satisfied with the meeting as a whole (96%). The factors associated with dissatisfaction regarding the quality of the scientific meeting were the masculine gender (OR = 2.7, CI 95% = 0.8-9.l, p = 0.06), having an M.Sc. or Ph.D. degree (OR = 2.3, CI 95% = 0.9-5.5, p = 0.03), and having attending prior meetings more than twice (OR = 5.0, CI 95% = 1.5-18.4, p = 0.001).Most of the attendants were satisfied with the scientific quality and discussions of the research work. The masculine gender, having an M.Sc. or Ph.D. degree, and prior assistance were the factors associated with dissatisfaction of the scientific quality of the Meeting.

Previous reports have shown that undernourished children with acute lymphoblastic leukemia (ALL) have a poorer long-term survival as compared with children with normal nourishment status. It has been shown that both the relapse and mortality rates of undernourished children with ALL are higher during the continuation phase of the chemotherapy and are apparently related to a poor tolerance of ablative chemotherapy. No previous articles have analyzed the early mortality rate of these patients.We carried out a case-control study, and have studied the effect of severe malnutrition on the mortality of 17 children with ALL during the initial induction-to-remission phase of the treatment. These 17 cases were compared with 76 controls who had survived at least the phases of induction and consolidation.It was found that the chance of dying during the initial phase of the treatment was 2.6 times higher (confidence interval 95%: 0.55-11.89) in undernourished children with ALL than in those children with normal nourishment status. The risk of death increased with the severity of undernourishment (p = 0.04).These data confirm the prognostic value of malnutrition in children with ALL and suggest that undernourishment may also influence early mortality during the induction-to-remission phase of the treatment.

To identify some differences of patients and medical characteristics related to autopsy authorization.Observational, cross-sectional study.Third-level medical care in a pediatric hospital.A specific mortality questionnaire was analyzed by members of the mortality staff, because they reviewed deaths which occurred between January 1994 and December 1995. Descriptive statistic and non-parametric tests (X2) were calculated to analyze data.A total of 408 deaths were evaluated, in which 116 autopsies were done (28.4%). Children less than 18 months of age had the highest frequencies of autopsies (33.3%-30.7%). The patients referred by other units and the autopsy application done by a medical resident, had the highest frequencies of acceptance (32.5%, 35.3%, p0.05). The detection of diagnostic and therapeutic problems were related with high frequencies of autopsies (37.7%, 36% p0.05).The results show us that some medical care factors are related to higher frequencies of autopsies. It is important to consider them in order to increase the capacity of teaching that a postmortem study has.

Cervical cancer is the most important cancer in Mexican women. Early detection is possible by means of the Papanicolaou (Pap) test; however, the coverage in Mexico is low.A cross-sectional survey was carried out in a representative sample of women from the Tlalpan area of Mexico City. Social, reproductive and health care factors associated with the lack of use of the Pap test with respect to adequate use and misuse were identified. Both bivariate and logistic regression analyses were used for the adjustment of variables.Of 1,215 women studied, 22.5% had never had a Pap smear, 42% had misused the test (90% of triennial performance), and 35.5% had adequately used the test (or = 90% of triennial performance). The main factors related to the lack of use were the following: not knowing about the Pap test (ORa = 35.16, 95% C.I. = 17.4-70.9); having fewer than 6 years of education (ORa = 4.5, 95% C.I. = 2.5-8.4); women younger than 30 years of age (ORa = 3.4 95% C.I. = 2.3-5.1); use of contraceptives (ORa = 0.4, 95% C.I. = 0.2-0.8); history of sexually transmitted diseases (ORa = 0.3, 95% C.I. = 0.1-0.8), and the principal informant about the Pap test, i.e., the health services personnel (ORa = 0.02, 95% C.I. = 0.0008-0.05).The lack of use and the misuse of Pap smears vary importantly among the different social and reproductive factors. But the principal reasons for lack of use were not knowing about the Pap test and a low educational level. We propose a greater diffusion on the benefits of the test in the Mexican population, through massive means of communication and health services.

The objective was to identify the characteristics of epidemiologic designs enabling their classification. A critical review of the literature in the clinical epidemiologic area was done to establish the main differences between designs. A meeting with experts to discuss this controversial topic and obtain criteria by consensus was organized. We propose an integral classification based on levels with two fundamental shafts: intervention and explanatory reasoning.

The objective of the study was to determine if children with high risk acute lymphoblastic leukemia (ALL) exhibit higher frequency of alterations in nutritional state during the phases of induction and consolidation of chemotherapy than children with low risk ALL, based on the arm muscle area. The design was concurrent comparative cohorts. It was performed at pediatric hematology service of the Hospital General del Centro Médico Nacional "La Raza" and hematology service of the Hospital de Pediatría del Centro Médico Nacional "Siglo XXI". One hundred-five patients were incorporated into the study: 53 with high risk (HR) ALL and 52 with low risk (LR) ALL. Basal measurements of arm circumference and tricipital skinfold were surveyed monthly (for 3 months) by standardized personnel. Altered nutritional state during follow-up was defined as the loss of 10% or more of the arm muscular area (AMA) measured at diagnosis. Statistics of proportion analysis with a significance level of 0.05 and relative risk (RR) with confidence intervals (CI) were calculated. In the first month the RR was 0.77 (CI 0.31-1.87); the LR group was the most affected. In the second month the RR was 7.31 (CI 1.41-38.03); the most affected group was the HR. In the third month the RR was 1.77 (CI 0.60-4.92); the HR group was the most affected. High-risk patients show a higher frequency of nutritional state alterations reflected in AMA during the second month after diagnosis. This may be caused by the more aggressive chemotherapy received by these patients.

To determine the frequency, time of occurrence and factors associated with the failure of the permanent peritoneal catheter during dialysis in cases of chronic renal failure (CRF).A retrospective cohort under a nested case control design was studied at a second level health care unit of the Instituto Mexicano del Seguro Social. A total of 149 catheters, double cushion straight Tenckhoff type, were evaluated in 74 patients with CRF due to diabetic nephropathy in 36/74 patients (49%). Information concerning functionality time and causes of catheter failure as well as the clinical and technical factors concerning insertion were obtained from the clinical chart.The cumulated time of dialysis was 814 months. Catheter failure occurred in 101 cases (68%): 67 due to obstruction, 24 due to infection, to leakage in 6 and to other causes in 4. Those of non-infectious origin were more frequent (p0.01). In the first month post-insertion there was a higher number of failures than after one month, (p0.0005). The global functionality of the catheter at one month, one and two years was 55%, 31% and 16%, respectively. There was a greater permanence of the catheters in continuous ambulatory peritoneal dialysis than in intermittent peritoneal dialysis (p = 0.02).It is concluded that the frequency of the peritoneal catheter failure was high; that the most frequent cause was due to non-infectious complications during the first month of insertion; and the factor associated to catheter failure was intermittent peritoneal dialysis as compared to continuous ambulatory dialysis.

The objective of this study was to determine the validity of a questionnaire to measure daily performance as an evaluation of quality of life in pediatric leukemia patients. A questionnaire of the daily activities of a child according to Lickert's criteria was done. A pilot survey was performed in patients without a chronic or disabling disease in order to assess its validity. The impression of the medical attendance of each pediatric patient with leukemia, of their daily performance, was compared with the results of the instrument. A trained nurse applied the questionnaire to 60 mothers of patients (29 female/31 male) as outpatients during the clinical review. Fifteen questionnaires were applied twice to evaluate its consistency. According to the results, 77% of the patients were in remission. 15% in relapse, and 8% during induction to remission. The mean age of the patients was 9 = 3.6 years, ranging from 2-16 years. One hundred percent of the patients obtained a satisfactory grade greater than 35 points. In conclusion, the questionnaire identified adequately the level of the daily performance in addition to the specific affected areas of the patients with leukemia. Our findings are that their level of performance is satisfactory and is not affected because of the disease or the phase of the treatment.

The aim of this study was to obtain the cut point to determine an individual's seronegativity with respect to measles using commercial reagents. To determine the test sensitivity, the serum of 22 individuals 21 years of age or older, and a positive history of measles (positive control group) was studied. For specificity, the serum of 22 children 15 to 24 months old, and no measles vaccination record nor positive history of measles (negative control group), was analyzed. The antibodies titer determination for both groups was done using the ELISA technique and the Brunell method, subsequently, as well as a ROC curve (Received Operating Curve). When the Brunell method was used, the cut points were 0.4090 (sensitivity 1.0 and specificity 0.95) and 0.5042 (sensitivity 0.95 and specificity 1.0). When a ROC curve was done the cut point was 0.4500, with a sensitivity and specificity of 100 per cent. It was also concluded that the latter is the best method to obtain this cut point, because it does not establish arbitrary values when the data distribution does not follow a normal pattern.

The simple linear regression analysis, multiple linear regression and logistic regression constitute powerful statistical analysis tools widely used in clinical research. These kinds of analyses are based upon mathematical models which at the same time are established on certain basic assumptions. The regression analysis assumptions are basically: a) that the model is really linear, b) that the distribution of data is normal (from a statistical point of view), c) that the variances of the employed data are homogeneous (homocedastics) and that the included data are independent. The regression diagnostic has become popular as a form to evaluate if the assumptions have been accomplished, one of its most important techniques is the residual analysis. A residual can be defined as the value which measures the distance between the regression line and the corresponding value of the variable "y". Among these kinds of residuals used to evaluate the assumptions of regression are: the crude residual, the standardized, of student and the jackknife. The most useful among them is the jackknife residual. The usefulness and limitations of the residuals in the evaluation of the regression analysis assumptions are described, basically referring to the identification and handling of extreme values (outliers).

1. To identify the quality degree of medical care in patients with acute leukaemia who had fever and granulocytopenia during the hospitalization period. 2. To establish the relationship between the medical care process and the results in this concern.Retrospective survey.Children's Hospital of the Mexican Institute of Social Security.Twenty three patients with acute leukaemia were studied. Also, hospitalization episode of these patients, in which they suffered fever and granulocytopenia, was randomly selected.Compliance of diagnostic and therapeutic process was measured during hospitalization, according to the protocolized recommendations made by consensus of the hospital expert group. In order to identify the quality degree of medical care, it was taken into account the protocol compliance besides the results observed in the patients. Results were assessed based on patients' survival to fever and granulocytopenia episode, as well as on fever's duration. The correlation was calculated by using Spearman's coefficient.The medical care quality of the hospital was "adequate" (85% on average). Compliance degree, including the total process was 71%; with diagnostic process 63%, and with therapeutic process 76%. The results observed in the patients were considered as "adequate" (89%). By evaluating individual cases, the medical care quality was considered excellent or adequate in 17 patients (74%) regular in five (22%) and poor in one (4%). Diagnostic process was adequate in 6 patients (26%) regular in 12 (53%) poor in three (13%) and very bad in two (8%). On the other hand, therapeutic process was excellent in 14 patients (60%) regular in one (4%) poor in six (26%) and very bad in two (9%). Results observed in 13 cases were excellent (57%) adequate in eight (35%) regular in one (4%) and very bad in one (4%). The relationship between process and result was 0.41 (P0.05) between diagnostic process and result 0.14 and, between therapeutic process and result 0.34.The medical care quality rendered to patients with leukaemia, who suffered a granulocytopenia episode and fever, was considered as adequate. Therapeutic recommendations were followed accurately, meanwhile, diagnostic process had a lower adherence. A positive relationship between process and result was observed.

Leukemia is the most frequent neoplasia in children; in our country it is the main cause of medical attention in children with cancer. The are different risk factors associated with the development of this kind of cancer.To identify which of the already known factors described in the literature associated with the development of leukemia are most frequent in the pediatric population of Mexico City.A protective case-control study was carried out using prevalent and incident cases. In two third level hospitals of Mexico City, a total of 81 children who had been diagnosed as suffering from different kind of leukemia, confirmed by biopsy of bone marrow, were select and studied. The control were 154 children from two different sources: 77 of them came from the same hospital where the cases received medical care, the selection criteria was not to have any kind of neoplasia; and 77 came from the same community where those diagnosed children cases lived, the selection criteria for this group was that they were healthy children. Both cases and community controls were visited at home and interview to complete precoded questionnaire with the different variables of the study. The information from the hospital controls was obtained during the time they stayed in the hospital. Odds ratio (OR's) for the different associations were calculated, as well as its confidence intervals at 95% (IC) accord to Cornfield and unconditioned logistic regression was carried out to control confounding variables.OR greater than 1 was found in those with familiar cancer background 1.93 (1.2-3.63); the mother being exposed to X-ray during pregnancy 1.89 (0.84-4.22); previous abortions before the child with leukemia was born 2.44 (1-06-5.68); being born from full term birth 2.42 (0.47-16.65); being born with weight greater that 3500 g 2.21 (1.04-4.33); being exposed to fertilizers 4.73 (1.04-24.14) and insecticides 1.93 (1.05-3.56). OR smaller than 1 was found in those who have been in a hospital because of an infectious disease during the first year of life 0.57 (0.17-1.74); to have suffered from chicken pox 0.59 (0.32-1.08). No association to parent's age or job was found. Multivariated analysis shows that the exposure to insecticide is the most important risk factor associated with the development of leukemia in children.We obtained positive associations to different risk factors described in the literature, having found that exposure to fertilizers is the most important risk factor and finding no association with the parent's occupation. This leads to the need of carrying out further studies to investigate, in more detail, the occupation of the father to confirm whether or not this is a risk factor.

There are different risk factors which have been related to the presence of leukemia in children. In the past years one of these factors has become relevant, the risk of living in an area near to high electric voltage lines, generators of electromagnetic fields of low frequency (EMF), which can cause development of leukemia in children.To learn whether living in an area close to EMF generator sources, electric transformers, high electric voltage distribution or transmission lines and electric substations, is a risk factor in the development of leukemia in children living in Mexico City.A projective study of case-control was accomplished. The cases were obtained from hospitals of the third level. The diagnosis of leukemia in its different varieties was confirmed through biopsy of bone marrow. The controls were selected in the same hospital from inpatients and outpatients with different problems, except neoplasia. A total sample of 81 cases and 77 controls was analyzed. The residence of the controls and cases were visited using a questionnaire coded with the different study variables. To diminish the memory bias in relation to EMF, the subjects were shown different pictures pointing out the different sources of exposures, which were asked. Having obtained the information, different odds ratios (OR) were calculated for the different associations, as well as the confidence intervals at 95% and an unconditioned logistic regression was accomplished to know the adjusted OR.There were no differences between the cases and controls according to the relative who gave the information, the current age of children, the parents's age, the social class and the parent's occupation. It was found that all the generating sources of EMF, which were involved in the study, had and OR above 1. Being the highest, the ones living near the distribution or transmission wires of high voltage with an OR of 2.63 (1.26-5.36) and 2.5 (0.97-6.67) respectively. When the distance of exposure was controlled, the highest OR was for distribution lines (OR 2.12; 0.79-5.85). When the analysis was applied to persons who have moved from the residence, it was found that the OR was above 1 in all the associations, the highest being the distribution wires and with the distance the highest was the electric substations. Furthermore, the multivariate analysis showed that the risk continued only for the distribution wires.The EMF exposure was found positive, however this is not very precise, that is why it is necessary to carry out other studies to confirm the existence of the association and correct possible biases which could appear during the research.

Objectives. 1) To identify the tests of immunological diagnosis with a high diagnostic efficiency in amebic liver abscess. 2) To determine the ideal cutoff point for such tests. 3) To identify the influence degree of the antigen used over the test efficiency. Design. Comparative survey. Study units. Analysis of 24 articles identified in the medical literature about tests of immunological diagnosis in amebic liver abscess. Measurements. Starting from the articles, operating characteristics curves (ROC) were established derived from the test application to patients with amebic liver abscess. Results. A great variability in the diagnostic efficiency was identified between the various tests, even when the analysis was focused on the investigations of a specific test. It was not possible to conclude which test had a major degree of efficiency due to such variability. The cutoff level considered as relevant was higher than the one traditionally used for indirect hemagglutination and it had concordance with the one presently accepted for the fluorescence antibodies test. By maintaining steady the spectrum of the study patients and the type of test, variability among the tests persisted. This was due to the use of different antigens. Conclusions. A great variation in the diagnostic efficiency of the analyzed tests was identified. The variation source was the type of test, the antigen used and probably the illness spectrum.

to determine the frequency and risk factors of non-compliance to oral metronidazole.comparative cross-sectional survey.111 patients who received oral metronidazole. SETTING CHARACTERISTICS: two medical units: one primary level unit and one secondary care unit of the Mexican Institute of Social Security.non-compliance was assessed by home interview and pill count.frequency of non-compliance was 55%. Risk factors for non-compliance were: female sex (OR = 3.0; p less than 0.05); side effects (OR = 3.1; p less than 0.05); low literacy (OR = 3.75; p less than 0.05). Stratified analysis showed no interaction between variables.frequency of non-compliance to metronidazole is high, and could affect the effectiveness of medical care. Female patients with low literacy and who suffer side effects are a high risk group for non-compliance.

To identify the mortality prognostic factors from a pediatric intensive care unit.Retrolective cohort study with an analysis of cases and controls (ambidirectional design). PLACE OF STUDY: The intensive care unit at a Pediatric Third Level Hospital.All of the patients admitted into the I.C.U. for a year (August 1989 to August 1990).The patients were identified when admitted into I.C.U., while evaluating their clinical course through their charts. Afterwards, they were placed into two groups, those who died while in I.C.U. (n = 49) and those in the control group which constituted the initial cohort survivors (n = 115). The prognostic factors evaluated were age, sex, diagnosis when admitted, organic failure, changes in diagnosis and treatment.164 patients were studied, with a slight predominance of the male sex (53%). The patient's age fluctuated between 1 day and 17 years of age, with a mean age of 10 months. The diagnosis established when admitted were predominantly dealing with infectious problems (n = 54, 32%). The most important prognostic factors seen during the bivaried analysis were the peritoneal dialysis (RM = 12.71, IC 95% = 2.41-98.29, P less than 0.01); a Glasgow index less than or equal to 10 points (RM = 7.33, IC 95% = 1.25-47.26, P less than 0.01), respiratory organic failure (RM = 6.32, IC 95% = 2.46-16.8, P less than 0.01) and assisted mechanical ventilation (RM = 5.61, IC 95% = 2.52-12.68, P less than 0.01).The mortality rate in I.C.U. was 30%. The most important prognostic factors associated to mortality after adjusting for severity were having a cardiovascular ailment, the need to administer blood products, a Glasgow index less than or equal to 10 points, heart and hematologic organic failure and when respiratory mechanical assistance was provided.

1. To determine the degree of correlation among different physicians concerning their initial diagnosis and 2. identify the degree of correlation between the probability that physicians assing an initial diagnosis and the number of days the patient is hospitalized, laboratory test and X-rays taken of the patient.A comparative questionnaire.Pediatric hospitalization Unit of a third level medical care ward of the Mexican Social Security Institute.All new admissions or non-programmed readmitted patients to the hospital during the months of November and December 1990.The treating physicians (Staff pediatricians (MB) and third (R3) and second (R2) year residents) were each asked to independently assign a probability (0 to 100) to each of the diagnosis emitted on the day the patient was admitted. When the patient was discharged, the number of days hospitalized as well as the number of laboratory tests and X-rays taken of the patient were added.106 patients were evaluated, a correlation was gathered between MBs and R3s of 0.79 (P less than 0.001) and among MBs and R2s of 0.83 (P less than 0.001). The correlation between resident physicians was discretely less 0.60 (P less than 0.01). When relating the probability assigned by the physicians and the number of days the patients were hospitalized, associations were observed of 0.31 (P less than 0.05), 0.15 (P less than 0.05) and 0.19 (P = 0.04) for the MB, R3 and R2s respectively. In the case of laboratory test a correlation of 0.38, 0.06 and 0.04 (MB, R3, R2 respectively) was found. None of these correlations were statistically significant. The X-rays showed a significant correlation in cases of the MBs (0.50, P less than 0.05).The probabilities assigned by the staff physician as well as the resident doctors are closely related and a lesser grade of association is seen when comparing the residents among each other. No tendencies were identified in the correlation of the probability assigned by the residents and the variables analyzed. A consistent relation was seen between the staff physician and high probabilities, longer stays, and greater number of laboratory tests and X-rays.

Meta-analysis is a research method which allows for the grouping of results from different studies relating to the same topic. Its main objective is to increase the precision surrounding the original research problem and provide a possibility to answer to different questions. This method has been developed in the areas of physics and the social sciences and has been widely accepted within the medical field. Its main use in medicine is in relation to the evaluation of therapeutic measures, yet its application has extended to the evaluation of diagnostic tests, etiological and prognostic factors. In spite of its development, there are still persisting problems in research difficult to solve because of the heterogeneity of the grouped studies, the identification of the size of the relevant effect and of the application of the results in clinical practice. The growing use of this research method within the medical field calls for its comprehension, as well as the recognition of its advantages and limitations in order for its users to be capable of judging the validity of individual meta-analysis.

In clinical pediatric research as in all research, one of the fundamental characteristics is the measurement of the studied features, either clinical, of laboratory or cabinet. A measurement must have two fundamental characteristics, for it to be considered as scientific: consistency and validity. The first one is centered on the variability of the measurement, which is due to the measuring instrument, to the subject or entity which is measured and to the individual or individuals who carry out the measuring, this is known as intra or interobserver variability, respectively. Validity is the fact of "actually" measuring what we want to measure. Both characteristics of measurement, are often mixed, between them and with other concepts, and this is the reason of not having a clear idea of what is the real meaning. This paper discusses the different terms that have been used for consistency and validity of a measurement. Also it points out how to assess consistency, from the validity, taking into account the measuring scale of the variables and the number of observers. Easy examples are used for the application of different formulas and for the interpretation of the results.

The effects of unilateral olfactory deprivation on the glial population during the olfactory bulb development have been studied. The lack of sensory stimulation has been found to be related to an increase in gliofibrillary acid protein (GFAP) in the three layers of the deprived bulbs. This increase is due to the higher number of astrocytes in the deprived bulb, which is much more noticeable in the plexiform layer than in the other two, together with a hypertrophy of the reactive astrocytes resulting in an increase in the number and thickness of their prolongations. Our results demonstrate that sensory olfactory deprivation acts as other noxius agents on the CNS, causing gliosis in the olfactory bulb. This gliosis is revealed by astrocytic hyperplasia and hypertrophy.

1. To describe the frequency of adherence to methodologic criteria proposed for assessment of diagnostic tests. 2. To identify potential bias. 3. To construct Receiver Operating Characteristic (ROC) curves based on data published on the assessed papers.Descriptive cross-sectional survey.All papers listed under diagnosis and immunological headings of amebiasis in the Index Medicus from 1970 to 1988.80 papers.a: Adherence to methodologic criteria proposed for assessment of diagnostic test. b: presence of potential bias.The adherence to methodologic criteria varied 1 to 55% of the papers. The comparison with a "gold standard" occurred in 40% the independent "blind" assessment occurred in 6% the setting for the study was described 1%. The study of an appropriate spectrum of disease was done in 11%. We were able to construct ROC curves with data from 37 papers and differences were observed among studies evaluating the same test. A high proportion of papers had potential bias.The adherence to methodologic standards is poor in the papers analyzed in this series. Consequently the frequency of potential bias was high.

The complexity of the clinical spectrum in human amebiasis and the high variability in laboratory methods used to detect Entamoeba histolytica infections have impeded the collection and evaluation of reliable epidemiological data. Thus, more sensitive, specific and standardized methods are needed in order to accurately identify infections with this parasite. An important step in the development of serological diagnostic methods is the identification and isolation of specific parasite antigens which are immunogenic in the host. In this work, we have standardized an electroimmunotransfer blot technique to characterize E. histolytica antigens recognized by antibodies present during human amebic infections. An important aspect was an investigation of technical variations in the preparation of cell lysates including the use of different protease inhibitors and solubilizing agents. The highest yield of protein was achieved by homogenization of trophozoites in the presence of 10 mM p-hydroxymercuribenzoate (pHMB) as a protease inhibitor and by lysis using Triton X-100 and a mixture of protease inhibitors. Recovery of degraded vs non-degraded proteins in the cell extracts was evaluated by gradient polyacrylamide gel electrophoresis. Both quantitative and qualitative differences were noted between the different methods of preparing soluble cell extracts. A more complete set of antigenic components was obtained by homogenization and use of pHMB. Thus parasite extracts prepared by this method were selected for protein transfer. In this, the optimal protein concentration was of 120 micrograms of protein per cm of gel width and efficient transfer of proteins to nitrocellulose sheets was achieved at 100 V for 2 hrs and at 4 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

To determine the efficacy of zymodemes of E. histolytica technique in an epidemiologic study. To report the zymodemes for the first time described in Mexico. To report the main difficulties in the correct classification of zymodemes in this study. To describe the zymodemes identified in two evaluations done in 100 healthy individuals.A cross-sectional survey and a cohort of healthy persons.We analyze the results of 1730 Robinson cultures performed in a cross-sectional survey done in the Municipality of Cadereyta, Queretaro, Mexico from October 1986 to August 1987. From positive cultures properly growth a Iysate was done and preserved in liquid nitrogen until the electrophoretic determination of 4 isoenzymes was done: EC 5.3.1.9. glucophosphate isomerase (GPI); EC 1.1.1.40 L-malate: NADP oxidoreductase (oxaloacetate decarboxylating) (ME); Ec 2.7.5.1 phosphoglucomutase (PGM); and EC 2.7.1.1 hexokinase (HK).Of 1730 cultures 289 (16.7%) developed trophozoites, in 100 (34.6%) was possible to make lysate and zymodeme. There were 67 ZNP, 3 mixtures (ZP and ZNP) and 30 ZP. There were two patterns for the first time described in Mexico (XVII and XVIII) and 30 strains had a pattern different from the 20 already described by Sargeaunt. Results observed in 100 individuals measured twice. [table: see text] There were 9 subjects in which zymodemes were isolated twice: at the first time 5 PZ and 4 NPZ, at the second time 1 PZ and 8 NPZ. At first time all 9 had negative serology and the second time one carrier of NPZ became positive.In our study one tirth of Robinson cultures positive to trophozoites reached lysate. Efficacy of zymodemes and CPS is similar. We report for the first time in Mexico two non-pathogenic zymodemes (XVII and XVIII). We also report 30 zymodemes non-classified according to the standard proposed by Sargeaunt, one explanation for this feature is the possibility of zymodemes variability or new patterns. In endemic populations zymodeme pattern varies with time in asymptomatic carriers.

A review was made of the clinical histories of 18 children who were admitted to the Emergency Department of the Hospital de Pediatría del C.M.N. (IMSS) with the diagnosis of nalidixic acid intoxication. The study covered a period of 3 years, from 1976 through 1978. There were no differences as to sex; infants under one year were most frequently attached; iatrogenesis was the most frequent mechanism. The clinical manifestations were characterized by neurological disorders of the state of alertness, hypertensive cranial syndrome and neuronal damage; there was metabolic acidosis in other cases. Treatment included gastric lavage, general measures, correction of acid-base unbalance, control of convulsive crises. Indications for the use of nalidixic acid are reviewed stressing that it must be used in urinary infections and as second choice drug.

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.