Accurate method for rapid biomass quantification based on specific absorbance of microalgae species with biofuel importance.

The development of microalgae culture technology has been an integral part to produce biomass feedstock to biofuel production. Due to this, numerous attempts have been made to improve some operational parameters of microalgae production. Despite this, specialized research in cell growth monitoring, considered as a fundamental parameter to achieve profitable applications of microalgae for biofuels production, presents some opportunity areas mainly related to the development of specific and accurate methodologies for growth monitoring. In this work, predictive models were developed through statistical tools that correlate a specific micro-algal absorbance with cell density measured by cell count (cells∙per ml), for three species of interest for biofuels production. The results allow the precise prediction of cell density through a logistic model based on spectrophotometry, valid for all the kinetics analysed. The adjusted determination coefficients ( r adj 2 ) for the developed models were 0·993, 0·995 and 0·994 for Dunaliella tertiolecta, Nannochloropsis oculata and Chaetoceros muelleri respectively. The results showed that the equations obtained here can be used with an extremely low error (≤2%) for all the cell growth ranges analysed, with low operational cost and high potential of automation. Finally, a user-friendly software was designed to give practical use to the developed predictive models.

Diagnosis of multiple sclerosis using multifocal ERG data feature fusion.

The purpose of this paper is to implement a computer-aided diagnosis (CAD) system for multiple sclerosis (MS) based on analysing the outer retina as assessed by multifocal electroretinograms (mfERGs). MfERG recordings taken with the RETI-port/scan 21 (Roland Consult) device from 15 eyes of patients diagnosed with incipient relapsing-remitting MS and without prior optic neuritis, and from 6 eyes of control subjects, are selected. The mfERG recordings are grouped (whole macular visual field, five rings, and four quadrants). For each group, the correlation with a normative database of adaptively filtered signals, based on empirical model decomposition (EMD) and three features from the continuous wavelet transform (CWT) domain, are obtained. Of the initial 40 features, the 4 most relevant are selected in two stages: a) using a filter method and b) using a wrapper-feature selection method. The Support Vector Machine (SVM) is used as a classifier. With the optimal CAD configuration, a Matthews correlation coefficient value of 0.89 (accuracy = 0.95, specificity = 1.0 and sensitivity = 0.93) is obtained. This study identified an outer retina dysfunction in patients with recent MS by analysing the outer retina responses in the mfERG and employing an SVM as a classifier. In conclusion, a promising new electrophysiological-biomarker method based on feature fusion for MS diagnosis was identified.

Coding Prony's method in MATLAB and applying it to biomedical signal filtering.

BACKGROUND: The response of many biomedical systems can be modelled using a linear combination of damped exponential functions. The approximation parameters, based on equally spaced samples, can be obtained using Prony's method and its variants (e.g. the matrix pencil method). This paper provides a tutorial on the main polynomial Prony and matrix pencil methods and their implementation in MATLAB and analyses how they perform with synthetic and multifocal visual-evoked potential (mfVEP) signals. This paper briefly describes the theoretical basis of four polynomial Prony approximation methods: classic, least squares (LS), total least squares (TLS) and matrix pencil method (MPM). In each of these cases, implementation uses general MATLAB functions. The features of the various options are tested by approximating a set of synthetic mathematical functions and evaluating filtering performance in the Prony domain when applied to mfVEP signals to improve diagnosis of patients with multiple sclerosis (MS). RESULTS: The code implemented does not achieve 100%-correct signal approximation and, of the methods tested, LS and MPM perform best. When filtering mfVEP records in the Prony domain, the value of the area under the receiver-operating-characteristic (ROC) curve is 0.7055 compared with 0.6538 obtained with the usual filtering method used for this type of signal (discrete Fourier transform low-pass filter with a cut-off frequency of 35 Hz). CONCLUSIONS: This paper reviews Prony's method in relation to signal filtering and approximation, provides the MATLAB code needed to implement the classic, LS, TLS and MPM methods, and tests their performance in biomedical signal filtering and function approximation. It emphasizes the importance of improving the computational methods used to implement the various methods described above.

Posttransplantation diabetes mellitus after liver transplant and the impact of family history of diabetes in a Mexican cohort.

INTRODUCTION AND AIMS: Posttransplantation diabetes mellitus (PTDM) is a serious long-term complication that has a negative impact on graft and patient survival. The purpose of the present study was to describe the incidence of PTDM in a Mexican cohort and evaluate its association with a previous family history of diabetes (FHD). METHODS: A retrospective single-center cohort study was conducted on patients undergoing liver transplantation (LT). The primary outcome was time from LT to PTDM. The diagnosis of PTDM was established using the ADA criteria. A mediation analysis that used adjusted Cox regression models and considered pretransplant prediabetes a mediator was performed, to determine the total effect and direct effect of FHD on PTDM. RESULTS: A total of 152 patients were included, with a median follow-up time of 41 months; 19.2% (n = 29) had pretransplant diabetes. During the follow-up time, 15% of patients developed PTDM (n = 23), with an incidence rate of 4.71 cases/100 person-years. PTDM was significantly higher in patients with FHD, compared with those with no FHD (8.72 cases/100 person-years vs 2.04 cases/100 person-years, respectively; p = 0.001). The adjusted hazard ratio of PTDM for FHD was 4.14 (95% CI 1.60-10.7), p = 0.005) and 3.48 (95% CI 1.35-9.01, p = 0.010), when further controlled for pretransplant prediabetes. CONCLUSION: The occurrence of PTDM was similar to that reported in most international studies. As with type 2 diabetes, family history plays an important role in the development of PTDM, even after accounting for pretransplant prediabetes. Patients with FHD should undergo a stricter metabolic program.

Current vision on diagnosis and comprehensive care in hepatic encephalopathy.

The first clinical guidelines on hepatic encephalopathy were published in 2009. Almost 14 years since that first publication, numerous advances in the field of diagnosis, treatment, and special condition care have been made. Therefore, as an initiative of the Asociación Mexicana de Gastroenterología A.C., we present a current view of those aspects. The manuscript described herein was formulated by 24 experts that participated in six working groups, analyzing, discussing, and summarizing the following topics: Definition of hepatic encephalopathy; recommended classifications; epidemiologic panorama, worldwide and in Mexico; diagnostic tools; conditions that merit a differential diagnosis; treatment; and primary and secondary prophylaxis. Likewise, these guidelines emphasize the management of certain special conditions, such as hepatic encephalopathy in acute liver failure and acute-on-chronic liver failure, as well as specific care in patients with hepatic encephalopathy, such as the use of medications and types of sedation, describing those that are permitted or recommended, and those that are not.

Approach to the patient with cholestasis and jaundice syndrome. Joint AMH, AMG, and AMEG scientific position statement.

The term cholestasis refers to bile acid retention, whether within the hepatocyte or in the bile ducts of any caliber. Biochemically, it is defined by a level of alkaline phosphatase that is 1.67-times higher than the upper limit of normal. Cholestatic diseases can be associated with an inflammatory process of the liver that destroys hepatocytes (hepatitis), withjaundice (yellowing of the skin and mucus membranes, associated with elevated serum bilirubin levels), or with both, albeit the three concepts should not be considered synonymous. Cholestatic diseases can be classified as intrahepatic or extrahepatic, depending on their etiology. Knowing the cause of the condition is important for choosing the adequate diagnostic studies and appropriate treatment in each case. A complete medical history, together with a thorough physical examination and basic initial studies, such as liver ultrasound and liver function tests, aid the clinician in deciding which path to follow, when managing the patient with cholestasis. In a joint effort, the Asociación Mexicana de Hepatología (AMH), the Asociación Mexicana de Gastroenterología (AMG) and the Asociación Mexicana de Endoscopia Gastrointestinal (AMEG) developed the first Mexican scientific position statement on said theme.

ZnO-based dye solar cell with pure ionic-liquid electrolyte and organic sensitizer: the relevance of the dye­oxide interaction in an ionic-liquid medium.

The use of non-volatile electrolytes and fully organic dyes are key issues in the development of stable dye-sensitized solar cells (DSCs). In this work we explore the performance of ZnO-based DSCs sensitized with an indoline derivative coded D149 in the presence of a pure ionic-liquid electrolyte. Commercial nanostructured zinc oxide and an electrolyte composed of iodine plus (1) pure 1-propyl-3-methyl imidazolium iodide (PMII) and (2) a blend of PMII with low-viscosity ionic liquids were employed to construct the devices. Without further additives, the fabricated devices exhibit remarkable short-circuit photocurrents and efficiencies under AM1.5 simulated sunlight (up to 10.6 mA cm−2, 2.9% efficiency, 1 sun, active area = 0.64 cm2) due to the high surface area of the ZnO film and the high absorptivity of the D149 dye. Impedance spectroscopy is used to characterize the devices. It is found that the addition of the low-viscosity ionic-liquid improves the transport features (leading to a better photocurrent) but it does not alter the recombination rate. The robustness of the dye­oxide interaction is tested by applying continuous illumination with a Xenon-lamp. It is observed that the photocurrent is reduced at a slow rate due to desorption of the D149 sensitizer in the presence of the ionic liquid. Exploration of alternative ionic-liquid compositions or modification of the ZnO surface is therefore required to make stable devices based on ZnO and fully organic dyes.

Psychosocial evaluation for liver transplantation: A brief guide for gastroenterologists. / Evaluación psicosocial para trasplante hepático: una guía breve para gastroenterólogos.

Liver transplantation is a lifesaving treatment that improves survival and quality of life. The procedure requires adequate transplant candidate selection carried out by a multidisciplinary team. Psychosocial evaluation is a necessary part of recipient selection and its primary aims are to identify problems and psychosocial needs of the patient and his/her family, to improve transplantation outcomes. Different psychosocial conditions are considered risk factors for morbidity and mortality after transplantation. The presence of those factors per se is not an absolute contraindication, thus adequate evaluation promotes equal access to healthcare, improves results, and optimizes resources. The present review provides an overview of and guidelines for the most important psychosocial issues during the pretransplantation phase.

Asociación Mexicana de Hepatología A.C. Clinical guideline on hepatitis B.

Hepatitis B virus (HBV) infection continues to be a worldwide public health problem. In Mexico, at least three million adults are estimated to have acquired hepatitis B (total hepatitis B core antibody [anti-HBc]-positive), and of those, 300,000 active carriers (hepatitis B surface antigen [HBsAg]-positive) could require treatment. Because HBV is preventable through vaccination, its universal application should be emphasized. HBV infection is a major risk factor for developing hepatocellular carcinoma. Semi-annual liver ultrasound and serum alpha-fetoprotein testing favor early detection of that cancer and should be carried out in all patients with chronic HBV infection, regardless of the presence of advanced fibrosis or cirrhosis. Currently, nucleoside/nucleotide analogues that have a high barrier to resistance are the first-line therapies.

Asociación Mexicana de Hepatología A.C. Clinical guideline on hepatitis B. / Asociación Mexicana de Hepatología A.C. Guía Clínica de Hepatitis B.

Hepatitis B virus (HBV) infection continues to be a worldwide public health problem. In Mexico, at least three million adults are estimated to have acquired hepatitis B (total hepatitis B core antibody [anti-HBc]-positive), and of those, 300,000 active carriers (hepatitis B surface antigen [HBsAg]-positive) could require treatment. Because HBV is preventable through vaccination, its universal application should be emphasized. HBV infection is a major risk factor for developing hepatocellular carcinoma. Semi-annual liver ultrasound and serum alpha-fetoprotein testing favor early detection of that cancer and should be carried out in all patients with chronic HBV infection, regardless of the presence of advanced fibrosis or cirrhosis. Currently, nucleoside/nucleotide analogues that have a high barrier to resistance are the first-line therapies.

Hemophagocytic syndrome following alemtuzumab treatment for multiple sclerosis: A case report.

BACKGROUND: Alemtuzumab is a monoclonal antibody targeting CD-52, used for treating relapsing-remitting multiple sclerosis (RRMS). METHODS: We present a case of a 44-year-old male with RRMS who was admitted due to fever and jaundice after starting treatment with alemtuzumab 12 months ago. RESULTS: He was diagnosed with hemophagocytic syndrome (HS). Liver biopsy revealed images of hemophagocytosis in Kupffer cells of lobular sinusoid. Management consisted of treatment with corticosteroids. CONCLUSION: HS is a severe condition marked by an excessive activation of the immune system that leads to a rapid and progressive multi-organ failure, so it is important to consider it in the differential diagnosis of a fever syndrome following the administration of alemtuzumab.

Diagnostic ability of multifocal electroretinogram in early multiple sclerosis using a new signal analysis method.

PURPOSE: To determine if a novel analysis method will increase the diagnostic value of the multifocal electroretinogram (mfERG) in diagnosing early-stage multiple sclerosis (MS). METHODS: We studied the mfERG signals of OD (Oculus Dexter) eyes of fifteen patients diagnosed with early-stage MS (in all cases < 12 months) and without a history of optic neuritis (ON) (F:M = 11:4), and those of six controls (F:M = 3:3). We obtained values of amplitude and latency of N1 and P1 waves, and a method to assess normalized root-mean-square error (FNRMSE) between model signals and mfERG recordings was used. Responses of each eye were analysed at a global level, and by rings, quadrants and hemispheres. AUC (area under the ROC curve) is used as discriminant factor. RESULTS: The standard method of analysis obtains further discrimination between controls and MS in ring R3 (AUC = 0.82), analysing N1 waves amplitudes. In all of the retina analysis regions, FNRMSE value shows a greater discriminating power than the standard method. The highest AUC value (AUC = 0.91) was in the superior temporal quadrant. CONCLUSION: By analysing mfERG recordings and contrasting them with those of healthy controls it is possible to detect early-stage MS in patients without a previous history of ON.

The Mexican consensus on nonalcoholic fatty liver disease. / Consenso mexicano de la enfermedad por hígado graso no alcohólico.

Nonalcoholic fatty liver disease (NAFLD) affects nearly one third of the population worldwide. Mexico is one of the countries whose population has several risk factors for the disease and its prevalence could surpass 50%. If immediate action is not taken to counteract what is now considered a national health problem, the medium-term panorama will be very bleak. This serious situation prompted the Asociación Mexicana de Gastroenterología and the Asociación Mexicana de Hepatología to produce the Mexican Consensus on Fatty Liver Disease. It is an up-to-date and detailed review of the epidemiology, pathophysiology, clinical forms, diagnosis, and treatment of the disease, whose aim is to provide the Mexican physician with a useful tool for the prevention and management of nonalcoholic fatty liver disease.

[Spontaneous bacterial peritonitis as form of presentation of idiophatic nephrotic syndrome in a black adult]. / Peritonitis bacteriana espontánea como forma de presentación de síndrome nefrótico idiopático en un adulto de raza negra.

Spontaneous bacterial peritonitis is a serious and frequent complication in childhood nephrotic syndrome. However, this type of complication is very rare in adult nephrotic patients. In the review realized only 15 cases are published with this complication, and none of them after the year 2000. Later we expose the case of a male of 25 years old, proceeding of senegal, with spontaneous bacterial peritonitis, acute renal failure and coagulopatia for malnutrition as form of presentation of a nephrotic syndrome flowery. Besides across the contributed case different aspects of the epidemiology and of the managing of these patients are discussed as well as the last publications on the options of treatment of the glomerulopatia responsible of the clinical symptoms.

Brief Test of Attention: Normative data for the Latin American Spanish speaking adult population.

OBJECTIVE: To generate normative data on the Brief Test of Attention (BTA) across 11 countries in Latin America, with country-specific adjustments for gender, age, and education, where appropriate. METHOD: The sample consisted of 3,977 healthy adults who were recruited from Mexico, Argentina, Peru, Paraguay, Honduras, Chile, Cuba, Puerto Rico, Guatemala, El Salvador, and Bolivia. Each subject was administered the BTA as part of a larger neuropsychological battery. A standardized five-step statistical procedure was used to generate the norms. RESULTS: The final multiple linear regression models explained between 11-41% of the variance in BTA scores. Although men had higher scores on the BTA in Honduras, there were no other significant gender differences, and this one effect size was small. As a result, gender-adjusted norms were not generated. CONCLUSIONS: This is the first normative multicenter study conducted in Latin America to create norms for the BTA; this study will have an impact on the future practice of neuropsychology throughout Latin America.

Hypotension, bradycardia, and asystole after high-dose intravenous methylprednisolone in a monitored patient.

We report a case of hypotension, bradycardia, and asystole after intravenous administration of high-dose methylprednisolone in a 73-year-old patient who underwent electrocardiographic (ECG) monitoring throughout the episode. There was a history of ischemic cardiac disease 9 years earlier. The patient was admitted with a pulmonary-renal syndrome with hemoptysis, rapidly progressive renal failure, and hypoxemia that required mechanical ventilation in the intensive care unit. After receiving advanced cardiopulmonary resuscitation, the patient recovered cardiac rhythm. The ECG showed a junctional rhythm without ventricular arrhythmia. This study reviews the current proposed mechanisms of sudden death after a high dose of intravenous methylprednisolone (IVMP). These mechanisms are not well understood because, in most cases, the patients were not monitored at the moment of the event. Rapid infusion and underlying cardiac disease were important risk factors in the case reported here, and the authors discount ventricular arrhythmia as the main mechanism.

Nutrition, dieting, and fitness messages in a magazine for adolescent women, 1970-1990.

PURPOSE: This study was designed to characterize nutrition and fitness messages presented between 1970-1990 in a magazine for adolescent women; to evaluate whether these messages changed over time; and to assess the body shape portrayed as desirable, and whether this changed over time. METHODS: A data collection form was developed to code nutrition and fitness-related written items, advertisements and recipes, and the page coverage allocated to these items. Body shape was assessed by measuring bust:waist and hip:waist ratios of photographs of models wearing bathing suits or underwear. Magazines from even years between 1970-1990 (n = 132) were coded. RESULTS: Both nutrition-related and fitness-related coverage emphasized weight loss and physical appearance. Half the major nutrition-related articles presented a weight-loss plan, and weight loss was frequently addressed in other nutrition articles. The primary reasons presented for following a nutrition of fitness plan were to lose weight and become more attractive. Statements that the product or service would promote weight loss were found in 47% of nutrition-related advertisements. Nutrition coverage did not exhibit a net change over time, whereas fitness coverage increased (F = 6.6, p < .005), and the ratio of nutrition: fitness coverage changed from 10:1 in 1970 to 0.75:1 in 1990. Models' body shapes were less curvaceous than those in magazines for adult women, and the hip:waist ratio decreased over time (F = 7.3, p < .01). CONCLUSIONS: The nutrition and fitness messages in this magazine for adolescent women emphasize body shape and appearance, similar to findings from adult women's magazines, and contribute to the cultural milieu in which thinness is an expectation for women. Between 1970-1990, the emphasis on fitness increased, and the body shape of models tended to become more linear.

[A 21-year-old male patient with nephrotic syndrome and "idiopathic" AA amyloidosis]. / Varón de 21 años con síndrome nefrótico y amiloidosis AA "idiopática".

A case is reported of a 21 year old man who suffered from Castleman's disease and systemic secondary amyloidosis. He was otherwise healthy until development of a history of edema and nocturia over 3 weeks. Physical examination was normal apart from ankle swelling. Renal biopsy showed amyloid deposits in the glomerulus with gentian violet and congo red. Positive staining by antibody against serum amyloid A protein was demonstrated. Nine months later because of persistent nephrotic syndrome, an abdominal tomography was performed and a mesenteric mass was detected. The patient underwent abdominal surgery. The histopathological examination showed plasma cell variant of Castleman disease and AA amyloidosis in the mass. After the removal of mesenteric mass, the proteinuria gradually decreased and disappeared, and no systemic findings were present.