Estimation of milk yield based on udder measures of Pelibuey sheep using artificial neural networks.

Udder measures have been used to assess milk yield of sheep through classical methods of estimation. Artificial neural networks (ANN) can deal with complex non-linear relationships between input and output variables. In the current study, ANN were applied to udder measures from Pelibuey ewes to estimate their milk yield and this was compared with linear regression. A total of 357 milk yield records with its corresponding udder measures were used. A supervised learning was used to train and teach the network using a two-layer ANN with seven hidden structures. The globally convergent algorithm based on the resilient backpropagation was used to calculate ANN. Goodness of fit was evaluated using the mean square prediction error (MSPE), root MSPE (RMSPE), correlation coefficient (r), Bayesian's Information Criterion (BIC), Akaike's Information Criterion (AIC) and accuracy. The 15-15 ANN architecture showed that the best predictive milk yield performance achieved an accuracy of 97.9% and the highest values of r2 (0.93), and the lowest values of MSPE (0.0023), RMSPE (0.04), AIC (- 2088.81) and BIC (- 2069.56). The study revealed that ANN is a powerful tool to estimate milk yield when udder measures are used as input variables and showed better goodness of fit in comparison with classical regression methods.

Bioactive compounds and antibacterial activities in crystallized honey liquefied with ultrasound.

The effect of ultrasound on the crystal size, phenols, flavonoids, Maillard products and antibacterial activity of crystallized honeys was studied. Three multifloral honeys (M), one monofloral (MO) and one honeydew (HD) honey were used. Ultrasound was performed at 42 kHz for different times (0, 5, 10 and 15 min). The antibacterial activities were tested against Salmonella typhimurium, Bacillus subtilis, Pseudomonas aeruginosa, Listeria monocytogenes, Staphylococcus aureus and Escherichia coli. In all honeys, the parameters analyzed had significant differences ((P < 0.05)). After 15 min of ultrasound the HD had increments of 44 mg of gallic acid/100 g of honey in phenols, and some M showed increase in flavonoids (5.64 mg of quercitin /100 g of honey) and improvement in inhibition against Salmonella typhimurium was 13.1%. In some honeys the correlation between phenols or flavonoids and antibacterial activity were significant ((P < 0.05)). No correlation was found between Maillard products and antibacterial activity. The ultrasound treatment effect on the crystal size, phenols, flavonoid, Maillard products, and antibacterial activity of crystallized honeys were different in each honey.

In-Plane Structure of the Liquid-Vapor Interface of an Alloy: A Grazing Incidence X-ray Diffraction Study of Bismuth:Gallium.

The liquid-vapor interface of a bismuth-gallium mixture (0.2 percent bismuth and 99.8 percent gallium) at 36 degrees C has been studied by grazing incidence x-ray diffraction. The data show, in agreement with thermodynamic arguments, that bismuth is heavily concentrated in the liquid-vapor interface. The x-ray diffraction data are interpreted with the assistance of a simple model that represents the interface as a partial monolayer of bismuth. This analysis leads to the conclusion that the bismuth concentration in the interface is about 80 percent, that there is no significant mixing of gallium and bismuth in the interface, and that the structure function of the interfacial bismuth is like that of supercooled bulk liquid bismuth.

Skeletal muscle PO2 during hypoxemia and isovolemic anemia.

We subjected anesthetized mechanically ventilated rabbits (n = 6) to sequential exchanges of blood for a 6% dextran solution and compared their responses with those obtained in a previous study on progressive hypoxemia (n = 7). Right atrial PO2 (PVO2)RA and hindlimb PO2 (PVO2)limb, measured at the level of the iliac bifurcation, were compared with tissue PO2 (PtiO2) histograms obtained with an array of surface microelectrodes placed over the biceps femoris muscle. Systemic O2 consumption (VO2) was measured with the expired gas method. Cardiac output and systemic O2 transport (TO2) were calculated. Six exchanges of blood for dextran produced decreases in hemoglobin from 10.8 +/- 0.4 to 2.7 +/- 0.2 g/dl (P less than 0.001). Critical TO2 (TO2crit), defined as the level of TO2 associated with initial decreases in control VO2, was similar for anemia and hypoxemia (40.5 +/- 5.6 and 40.1 +/- 5.3 ml.min-1.kg-1, respectively). At any given TO2 other than control TO2, the levels of (PVO2)RA and (PVO2)limb were greater in anemia than in hypoxemia (P less than 0.01), but the mean and the distribution of the PtiO2 histograms were similar in both conditions. Mean PtiO2 was significantly less than (PVO2)RA or (PVO2)limb, except for those values obtained during the control period. These results confirm our previous finding that PVO2 is not an accurate index of PtiO2 under conditions of tissue hypoxia. Furthermore, similar PtiO2 levels during anemia and hypoxemia suggest that VO2 is limited by decreases in O2 diffusion from the capillaries to the cells.

Relationship of venous PO2 to muscle PO2 during hypoxemia.

Anesthetized mechanically ventilated rabbits were subjected to progressive hypoxemia (n = 7) to determine the relationship of venous PO2 (PvO2) to skeletal muscle PO2 (PtiO2). Measures of arterial PO2 (PaO2), right atrial PO2 [(PvO2)RA], and hindlimb PO2 [(PvO2)limb], were obtained from the carotid artery, right atrium, and inferior vena cava, just above the level of the iliac bifurcation. Biceps femoris muscle PtiO2 was measured with a surface O2 microelectrode having eight measuring points. PaO2 was decreased from 90.3 +/- 5.4 to 26.8 +/- 0.8 Torr in five consecutive steps, followed by reoxygenation to 105.6 +/- 10.5 (SE) Torr. Measurements were obtained after each decrement in PaO2. A total of 128 measures of PtiO2 were obtained per experimental stage. The mean and distribution of the muscle PtiO2 histogram were determined. Measurements were compared with analysis of variance and the Newman-Keuls post hoc method. (PvO2)limb had similar values as the average muscle PtiO2 (PtiO2) for PaO2 values greater than 52.1 +/- 4.3 Torr, where (PvO2)limb became greater than PtiO2 (P less than 0.05). The lowest measures of (PvO2)limb and PtiO2 were 15.9 +/- 0.7 and 4.0 +/- 0.1 Torr, respectively (P less than 0.01). The PtiO2 histograms showed no evidence of increased microvascular heterogeneity with hypoxemia. We conclude that in hypoxemia PvO2 is greater than muscle PtiO2. This difference may be related to the establishment of significant physicochemical O2 gradients from erythrocyte to tissue cell.

Production of microbubbles from axisymmetric flow focusing in the jetting regime for moderate Reynolds numbers.

We analyze both experimentally and numerically the formation of microbubbles in the jetting regime reached when a moderately viscous liquid stream focuses a gaseous meniscus inside a converging micronozzle. If the total (stagnation) pressure of the injected gas current is fixed upstream, then there are certain conditions on which a quasisteady gas meniscus forms. The meniscus tip is sharpened by the liquid stream down to the gas molecular scale. On the other side, monodisperse collections of microbubbles can be steadily produced in the jetting regime if the feeding capillary is appropriately located inside the nozzle. In this case, the microbubble size depends on the feeding capillary position. The numerical simulations for an imposed gas flow rate show that a recirculation cell appears in the gaseous meniscus for low enough values of that parameter. The experiments allow one to conclude that the bubble pinch-off comprises two phases: (i) a stretching motion of the precursor jet where the neck radius versus the time before the pinch essentially follows a potential law, and (ii) a final stage where a very thin and slender gaseous thread forms and eventually breaks apart into a number of micron-sized bubbles. Because of the difference between the free surface and core velocities, the gaseous jet breakage differs substantially from that of liquid capillary jets and gives rise to bubbles with diameters much larger than those expected from the Rayleigh-type capillary instability. The dependency of the bubble diameter upon the flow-rate ratio agrees with the scaling law derived by A. M. Gañán-Calvo [Phys. Rev. E 69, 027301 (2004)], although a slight influence of the Reynolds number can be observed in our experiments.

Determinantes Sociales de la Salud: postura oficial y perspectivas críticas / Social Determinants of Health: official stance and critical views

La relación entre las desigualdades socioeconómicas y el proceso salud enfermedad ha sido demostrada desde hace ya algún tiempo. Su estudio y posibilidades de intervención, han sido motivo de análisis de actores académicos e institucionales que asumen posturas según la ideología o corriente de pensamiento en la que se inscriben. Con el ánimo de analizar las causas de las inequidades en salud y hacer algunas recomendaciones, la Organización Mundial de la Salud estableció en el año 2005 la Comisión sobre Determinantes Sociales de la Salud. Perspectivas latinoamericanas como la Medicina Social y la Salud Colectiva reconocen la preocupación de la Organización Mundial de la Salud, sin embargo critican la posición asumida por la Comisión y organizan la discusión alrededor de los ejes conceptual, ético y de acción política, proponiendo, a diferencia de la Comisión, buscar las causas de la inequidad y sus vías de solución en lo que significa la determinación social. Cuestionamientos al enfoque de los determinantes sociales de la Comisión llegaron también desde autores como Vicente Navarro, para quien no son las desigualdades las que matan, sino los responsables de esas desigualdades, llamando la atención sobre las relaciones de poder que se ocultan y sobre los responsables y beneficiarios de la inequidad. Finalmente con el objetivo de analizar la determinación social y la ubicación jerárquica de los determinantes sociales, se presenta el problema del hambre, inscrito en un circuito de reproducción y determinación que permite ubicar la particularidad y la generalidad en permanente interrelación.

The relationship between socioeconomic inequalities and the health-disease process has long been demonstrated. Its study and possibilities for intervention have been submitted to analysis by academic and institutional actors which take more or less critical stances depending on their paradigms. In order to analyze the causes of health inequities and provide some recommendations, the World Health Organization established the Commission on Social Determinants of Health in 2005. Latin American approaches such as Social Medicine and Collective Health recognize the concern of the World Health Organization, yet they strongly criticize the position taken by the Commission, and organize the discussion around the conceptual, ethical and political action axes; in addition, and unlike the Commission, they propose to search for the causes of inequity and its solution in the meaning of social determination. Likewise, authors such as Vicente Navarro also questioned the Commission’s approach to social determinants. For Navarro, it is not inequalities that kill people, but the actors responsible for those inequalities. He also draws the attention towards the hidden power relationships and the entities responsible for inequity and those benefitting from it. Finally, in order to analyze the social determination and the hierarchical location of the social determinants of a particular problem, the issue of hunger is presented as embedded in a reproduction-determination cycle that makes it possible to locate the specificity and generality that are in constant interplay.

[Scintigraphic criteria for the diagnosis of pulmonary embolism]. / Criterios centelleográficos para el diagnóstico de las embolias pulmonares.

The natural history of pulmonary embolism is described, together with the physiopathologic alterations and the clinical manifestations of this disease, correlating these with the various patterns of pulmonary perfusion usually found by lung scintigraphy with 99mTc-MAA in patients with thromboembolic lung disease. By using data found in the literature, the operating characteristics (sensitivity, specificity, and accuracy) and the predictive values of the different scintigraphic patterns, were calculated for populations with different prevalences of pulmonary embolism. It is concluded that perfusion lung scintigraphy is a non-invasive, objective and fast procedure, very sensitive to alterations of the regional blood flow, but that is not specific for embolism. In some cases it can replace pulmonary angiography but in others, its results may indicate the performance of invasive procedures.

[Bayesian analysis of myocardial scintigraphy using 99mTc-Sn(II)-methylenediphosphonate and using 99mTc-Sn(II)-pyrophosphate]. / Análisis bayesiano de la centelleografía miocárdica con 99mTc-Sn (II)-metilendifosfonato y con 99mTc-Sn (II)-pirofosfato.

Myocardial scintigraphy with 99mTc-Sn (II)-Methylenediphosphonate (MDP) and with 99mTc-Sn (II) pyrophosphate (PPi) was performed in 185 patients with proven acute myocardial infarction (90 with MDP; 95 with PPi), and in 65 subjects with acute chest pain of a different etiology (37 with MDP; 28 with PPi), during the first five days after the onset of illness. Sensitivity, specificity and accuracy of the procedure were higher with PPi (0.895, 0.893, 0.894) than with MDP (0.822, 0.865, 0.835) in the diagnosis of AMI. Based on the usual clinical electrocardiographic and biochemical criteria, the likelihood of AMI on the population studied with MDP was of 70.9% and with PPi of 77.2%. Application of Bayes' theorem showed an increase in the likelihood of AMI, when myocardial scintigraphy was positive, from 70.9% to 93.7% when MDP was used, and from 77.2% to 96.6 when PPi was the tracer, with incremental ruling in gaings of 22.8% and 19.4%) respectively. A normal scintigraphy, on the other hand, reduced the likelihood of AMI from 70.9% to 33.4% when MDP was used, and from 77.2% to 29.2% when PPi was the tracer, with respective incremental ruling-out gains of 37.5% and 48.0%. Although homogeinity between the populations studied with each tracer was not proven, existing practical, clinical and biochemical evidence allows the conclusion that PPi is a better agent than MDP in the study of patients with acute chest pain.

[Predictive value of 99m-Tc-Sn(II) methylene diphosphonate in the study of acute myocardial infarction]. / Los valores predictovos de la centelleografía con 99m Tc-Sn (II) metilendifosfonato en el estudio del infarto agudo del miocardio.

Myocardial scintigraphy with 99mTc-Sn (II)-Methylenediphosphonate (MDP) was performed in 90 patients with proven acute myocardial infarction (AMI), and in 37 subjects with acute chest pain of a different etiology, during the first five days after the onset of their illness. The procedure was 82.2% sensitive, 86.5% specific, and 83.5 accurate for the diagnosis of AMI. Based on the usual clinical, electrocardiographic and biochemical criteria, the likelihood of AMI in this population was of 70.9% before the scintigraphic test. Application of Bayes' Theorem showed an increase in the likelihood of AMI, from 70.9% to 93.7%, when myocardial scintigraphy was positive, an incremental ruling-in-gain of 22.8%. A normal scintigraphy, on the other hand, reduced the likelihood of AMI, from 70.9% to 33.4%, an incremental ruling-out gain of 37.5%. It is concluded that myocardial scintigraphy with MDP is an important clinical procedure for the study of patients with acute chest pain: a positive test tends to confirm AMI, while a normal image, although it reduces the likelihood of this disease, is not particularly helpful in ruling it out.

[Pulmonary scintigraphy using the inhalation of monodispersed radioactive aerosols. Preliminary report]. / La centelleografía pulmonar mediante la inhalación de aerosoles radiactivos monodispersos. Informe preliminar.

This article describes a method for inhalatory lung scintigraphy (ILS) by the use of radioactive monodisperse aerosols, with particles smaller than 2 microns. We discuss the findings in normal subjects, in patients with pulmonary embolism (PE) or/and obstructive pulmonary disease (OPD), and in individuals with severe pulmonary hypertension. This procedure has several advantages over the use of radioactive gases, such as 133Xe and 81Krm: lower cost, easier to perform, several scintigraphic projections in one study, acquisition of perfusion and inhalatory images in a single session, and inhalatory and perfusion images with identical spatial resolution and similar data density. It is concluded that ILS with radioactive monodisperse aerosols is a useful method for the study of OPD and in conjunction with perfusion lung scintigraphy is helpful in the diagnosis of PE.

[Evaluation of radioactive phosphate scintillography in relation to time elapsed after acute myocardial infarct]. / Evaluación de la centelleografía con fosfatos radiactivos en relación con el tiempo de evolución del infarto agudo del miocardio.

A consecutive series of 205 myocardial scans, performed with 99mTc-labeled phosphates, in 185 patients with acute chest pain, were independently evaluated by comparing myocardial concentration intensity of the tracer to that in bone, and by rating this intensity by a six-category rating scale, which imply five criterion levels for calling an image "positive". The optimal criterion level was determined for each day of evolution of illness, as the one in which a shift to a more lax criterion level produces a bigger increment in false-positive results than in True-positive results, and in which a shift to a stricter criterion level causes a greater decrease in true positive results than in false-negative results. In all instances, the optimal criterion level was that with a moderate (2+) myocardial tracer concentration, lower than rib uptake, but with a focal pattern of myocardial distribution of the tracer (2F). By using this optimal criterion level, our results agree with the general consensus in that the procedure's usefullness is restricted to the first five days of evolution of illness. However, our daily statistical analysis showed that the best period to obtain the maximal diagnostic efficiency lies between the third and fourth days after the onset of acute chest pain. A negative result during this period, in patients with ECG and CPK serum concentration compatible with acute myocardial infarction, should be considered of prognostic significance, since it may translate a defficient colateral coronary circulation.

[Plasma cortisol response after stimulation with ACTH in postmature newborns (author's transl)]. / Respuesta adrenocortical tras estímulo ACTH en recién nacidos postmaduros.

Authors have studied, in three series of newborns-I) normal term: II) small for date, and III) postmature-, the basal levels of plasmatic cortisol and after stimulation with ACTH. Blood samples were obtained at the 48 hours and 10 days of life, respectively. There are not significative differences in the three groups neither in the basal levels of plasmatic cortisol nor after stimulation (p greater than 0.05). These results show no correlation between postmaturity and fetal adrenal primary or secondary hypocorticism.

[Formation and migration of radioactive microemboli to the lung during radiovenography]. / Formación y migración de microembolias radiactivas al territorio pulmonar durante la radiovenografía.

Two patients with lower extremity thrombophlebitis were studied by radionuclide venography with macroaggregated albumin labelled with 99mTc. Data analysis was performed with a new method. It generated sequential series of imagen (1-2 sec/frame) of the transit of the tracer through leg, thigh, and abdomen, allowing a more precise definition of temporal changes on regional radioactivity. This method rendered the first real evidence of the binding of the tracer to pre-existent venous thrombi, of the dislodgement of these and their gradual fragmentation during their transit to the lungs. The patients had no complaints during or after the study. Lung scanning, performed 24 hours later, showed slight alteration on regional lung perfusion in one case, and none in the other. It is concluded that radioactive microemboli to the lungs is a minor complication of radionuclide venography, which does not justify prevention. This could only nullify the sensitivity of the procedure.

[Evaluation of the experience of the observer in the interpretation of myocardial scintillography with radioactive phosphates]. / Valoración de la experiencia del observador en la interpretación de la centelleografía del miocardio con fosfatos radiactivos.

Two-hundred-and five myocardial scans with radioactive phosphates, performed in 185 patients interned at the Coronary Care Unit due to acute chest pain (147 myocardial infarcts: 58 coronary heart disease), were independently interpreted by six observers with different degrees of experience on the lectures of these kind of images (two nuclear physicians, two cardiologists, and two fellows of the Nuclear Medicine Unit). A series of six different grades of myocardial concentration of the radioactive phosphates, related to its osseous concentration were followed. Each observer reported the grade of concentration he found in each image. The fraction of myocardial infarcts and of coronary heart disease found by each observer in every grade of concentration were calculated. With these data, it was determined the optimal criterion level of each observer by which he attained the minor incidence of false negative and false positive results. Four observers found their optimal criterion level on 2F, where grades 0-2D are considered as negative, and grades 2F-4 are considered as positive. One observer found his optimal level at 2D (0-1: -; 2D-4: +) and other at 1 (0: -; 1-4: +. By using a decision matrix which relates results of the test with a binary outcome (normal, abnormal) to the actual diagnosis, also with a binary outcome (infarct, no infarct), the ratios for "sensitivity", "specificity" and "accuracy" were derived for each observer performing at his particular optimal criterion level. Our results suggests that the observer performance depends on his particular degree of experience in interpreting nuclear medical images and on his visual perception. It was concluded that it is necessary to periodically evaluate the individual optimal criterion level of the physicians in charge of the lectures of the myocardial images with radioactive phosphates, liable to shift with time in relation to the experience of the observer. The need of a more objective procedure to quantitate myocardial concentration of the radioactive phosphates is also implied.

[Usefulness of technetium 99m diphosphate scintellography in the diagnosis of acute myocardial infarction. Electrocardiographic correlation]. / Utilidad de la centelleografía con tecnesio 99m-difosfonatos para el diagnóstico de infarto agudo del miocardio. Correlación electrocardiográfica.

We made myocardial gammagraphies on a group of 141 patients with acute thoracic pain, using 99 mtc diphosphonates. We obtained images with three projections (LOA, LL and PA); for reading the gammagraphy we used the diagnostic criteria of Berman and Cols. Studying 106 patients with acute myocardial infarction we found affirmative diagnosis in 89 cases (83.93%). In another group, 32 patients with chest angina, the results were negative in 20 cases (62.5%). We got a total of eight false positive images in patients showing post-infarction aneurism, post-defibrillation damage, and myocardial metastatic tumors. This method showed a specificity of 62.9%. Correlation with the electrocardiogram refering to the localization of the infarction, was of 85.39%. This method proved to be of high sensibility and specificity in confirming the diagnosis of acute myocardial infarction or establishing it with certainty in some patients when the electrocardiogram fails and, in some cases, to find out about the evolution and prognostic of the acute myocardial infarction.

Qualitative radionuclide angiocardiography in the diagnosis of corrected transposition.

Seven patients with corrected transposition were studied by qualitative radionuclide angiocardiography. In four patients with situs solitus with apex on the left, the pulmonary artery was in a medial and posterior position, to the right of the aorta, with its root attached to the morphological left ventricle positioned on the right. The aorta arose from the ventricle placed on the left and had an anterior position. The ventricle located on the right has a triangular shape. In the case of situs solitus with dextroversion, the pulmonary artery was to the right of the aorta and had a right-to-left direction. The ventricle placed on the right was ovoid. In one single case of situs inversus with levoversion, the pulmonary artery was on the left, emerging from the morphological left ventricle placed on the left, and was ovoid in shape, while the aorta was on the right arising from the morphological right ventricle. In one case of situs inversus with dextrocardia, atrioventricular relationships were the same as in levoversion but the apex was on the right and the morphological left ventricle was triangular. Qualitative radionuclide angiocardiography is a simple and non-invasive method for obtaining morphological data for the precise diagnosis of corrected transposition.

[Upper digestive hemorrhage in patients older than 60 years of age]. / Hemorragia digestiva superior en pacientes mayores de 60 años.

We reviewed 286 records of patients older than 60 years with upper GI bleeding from 1985 to 1990. The average age was 72.7 +/- 8.9 y. The most common etiologies were: Gastric Ulcer 26%, Erosive gastritis 24%, Esophageal varices 16%, Duodenal Ulcer 13%, Miscellaneous 17% and Unknown causes 3%. Global mortality rate was 38% and the most frequent cause was variceal bleeding in 36%.