Distribution of metals in tissues of captive and wild Morelet's crocodiles and the potential of metallothioneins in blood fractions as a biomarker of metal exposure.

The distribution of Hg, Cd, Cu, and Zn in keratinized tissues, blood fractions, and excretory organs, and MTs in blood fractions and excretory organs was determined in captive, semicaptive, and wild Morelet's crocodiles and they were compared to select the most useful non-destructive tissues for the monitoring of metal exposure and to assess the potential of MTs as a biomarker. Our results indicate blood plasma, claws, and caudal scutes altogether are suitable tissues for xenobiotic metals exposure, with concentrations in blood plasma being an indicator of recent exposure, whereas concentrations in claws and caudal scutes are indicators of chronic exposure. Results in keratinized tissues suggest they are an important detoxification strategy in crocodiles, and claws presented the highest concentrations of metals in both captive (Hg = 0.44 ± 0.23 µg g-1, Cd = 11.10 ± 5.89 µg g-1, Cu = 45.98 ± 23.18 µg g-1, Zn = 124.75 ± 75.84 µg g-1) and wild populations (Hg = 1.31 ± 0.32 µg g-1, Cd = 26.47 ± 21.15 µg g-1, Cu = 191.75 ± 165.91 µg g-1, Zn = 265.81 ± 90.62 µg g-1). Thus, they are an appropriate tool for assessing metal exposure in populations where scutes clipping as a marking technique is not allowed, and their collection is less complicated than with other tissues. MTs are a suitable biomarker in blood plasma, whereas in erythrocytes detoxification processes might depend on hemoglobin, rather than MTs. Future studies should consider the implementation of these tools for the monitoring of wild populations.

Mercury and metallothioneins in blood fractions and tissues of captive Morelet's crocodiles in Quintana Roo, Mexico.

Even though studies of heavy metals and their relation with metallothioneins (MTs) in reptile tissues have been conducted, research on heavy metals and MTs in organs and blood fractions of crocodylians is limited. To date there are no studies on the distribution of MTs in organs and their relation with mercury (Hg), or the concentration of MTs in plasma and erythrocytes of crocodylians. In order to understand the role of MTs in crocodiles, our aim was to assess the detoxification mechanisms for exposure to metals in Morelet's crocodile (Crocodylus moreletii) by using two biomarkers (Hg and MTs) in blood fractions and tissues, and comparing them with concentrations between two populations of crocodiles, one previously wild and currently captive (Theme Park) and another raised in a Wildlife Management Unit (WMU). The caudal scutes from the Theme Park showed higher concentrations of Hg than those from the skin in the WMU samples, and significant negative relationships were observed between the total length (TL) and Hg in the scutes. The significant negative relationship between Hg and hemoglobin (Hb) may be due to disorders in the oxidation process and even denature of this protein, while the positive trend observed between MTs and Hb is consistent with the detoxifying functions and the protection against oxidative damage. This study is the first to report Hg in the erythrocytes of crocodylians and the use of MTs for testing the potential of these biomarkers as a tool to assess Hg exposure in crocodile's habitats.

Knowledge of bisphosphonate-related osteonecrosis of the Jawsamong Mexican dentists.

BACKGROUND: Bisphosphonate-related osteonecrosis is an infrequent but potentially serious complication. Its treatment remains complex, and in some cases can be mutilating. Prevention, a correct diagnosis and opportune management are crucial. MATERIAL AND METHODS: A cross-sectional study was made, interviewing 410 dentists with the aim of assessing their knowledge of the subject. RESULTS: Practically all of the dental professionals (99.7%) were found to lack sufficient knowledge of the prevention, diagnosis and management of bisphosphonate-related osteonecrosis. CONCLUSIONS: Actions including increased diffusion in the professional media and inclusion of the subject in training programs are needed in order to enhance the knowledge of bisphosphonate-related osteonecrosis among dentists and thus prevent complications in this group of patients.

Metals and metallothioneins in Morelet's crocodile (Crocodylus moreletii) from a transboundary river between Mexico and Belize.

The aim of this study was to determine concentrations of heavy metals (cadmium [Cd] and mercury [Hg]) and metallothioneins (MTs) in blood plasma and caudal scutes of Morelet's crocodile (Crocodylus moreletii) from Rio Hondo, a river and natural border between Mexico and Belize. Three transects of the river (approximately 20 km each) were surveyed in September 2012 and April 2013, and samples were collected from 24 crocodiles from these areas. In blood plasma, Cd (7.6 ± 9.6 ng/ml) was detected in 69 % of samples (n = 9); Hg (12.2 ± 9.2 ng/ml) was detected in 46 % of samples (n = 6); and MTs (10,900 ± 9,400 ng/ml) were detected in 92 % of samples (n = 12). In caudal scutes samples, Cd (31.7 ± 39.4 ng/g) was detected in 84 % of samples (n = 12) and Hg (374.1 ± 429.4 ng/g) in 83 % of samples (n = 20). No MTs were detected in caudal scutes. Hg concentrations in scutes from the Rio Hondo were 2- to 5-fold greater than those previously reported in scutes from other localities in northern Belize. In blood plasma, a significant positive relationship between Hg and body size was observed. Mean concentrations of Cd and MTs in size classes suggest that MTs may be related to Cd exposure. This is the first report of MT presence in crocodile blood.

Performance of alginate films for retention of L-(+)-ascorbic acid.

In view of acting as controlled delivery systems for nutritional supplementation, therapy or antioxidant activity at interfaces, alginate films of different copolymer composition and glycerol plasticizer levels were developed in the presence of Ca(2+) for achieving higher stability of L-(+)-ascorbic acid (AA). The ability of the alginate network to preserve AA from hydrolysis, tested by storage under vacuum at 25 °C, only decreased with the relative humidity (RH) increase when alginates were mainly constituted by guluronic-guluronic acid blocks (GG), whereas also decreased with the glycerol level increase when mannuronic-mannuronic acid (MM) and/or alternating guluronic-mannuronic (GM+MG) flexible blocks were present in higher proportions. This result could be probably related to the lower capability of the latter alginate block compositions to immobilize water in the network as they are not able to constitute Ca(2+) mediated junction zones where water molecules are highly retained. Films also studied under air storage showed that even at less favorable conditions of RH and glycerol levels, both GG and GM+MG enriched alginate networks in general preserved AA from oxidation. It also demonstrated that hydrolysis is the principal way by which AA is lost when supported in films.

[Stem cell implant with neck-head decompression for aseptic necrosis of the femoral head]. / Implante de células madre con descompresión cérvico-cefálica por necrosis aséptica de la cabeza femoral.

Adult aseptic necrosis of the femoral head progresses from its reversible phase, stages I-II-III (Ficat-ARCO), to stages IV-V coxarthrosis, and this represents a health problem. An observational, descriptive, prospective, case-series type of study was conducted to prove the hypothesis that the boring decompression of the femoral neck-head cancellous layer, together with the local implantation of multipotent adult autologous stem cells processed according to Ficoll at approximate amounts of 16.1 x 10(6) cells/ml, is the treatment of choice for stages I-II-III of aseptic necrosis of the femoral head. These cells create the necessary tissue conditions to preserve the structure of the femoral head thus avoiding or delaying its degeneration and the resulting prosthetic arthroplasty. A total of 16 patients with a diagnosis of stages I-II-III aseptic necrosis of the hip, ages 40-70, all of whom were at the reversible stage and accepted the above mentioned procedure, were included. The evaluation was conducted in June 2011 applying Harris' pain-function scale. Its score was used to determine the mean, the standard deviation and the median. Pain relief and functional recovery without surgical or immune complications were proven. According to Harris' score, 3 stage-III patients were under the median. One stage-III patient required prosthetic arthroplasty, so 93.7% of the patients retained their femoral head more than 2 years after the surgery. We conclude that the proposed procedure is the procedure of choice for stages I-II and it makes us be more selective in the case of stage III necrosis.

Isolation of pectin-enriched products from red beet (Beta vulgaris L. var. conditiva) wastes: composition and functional properties.

The present work was dedicated to the development of an extraction process for red beet (Beta vulgaris L. var. conditiva) by-products that preserves the high molecular weight of the macromolecules with the primary aim of waste upgrading. Our study concerns the extraction of pectin-enriched products with potential thickening properties for their usage in food formulation, as well as with some healthy physiological effect, by using citrate buffer (pH = 5.2) either alone or with enzymes (hemicellulase or cellulase) active on cell wall polysaccharide networks. Considering that red beet tissue contains ferulic acid, which cross-links pectin macromolecules through arabinose residues to anchor them into the cell wall, an alkaline pretreatment was also evaluated in order to perform polysaccharide hydrolysis in the cell wall network to accomplish higher renderings. Chemical composition and yield, as well as the in vitro glucose retention exerted by the isolated fiber products were finally analyzed.

Epithelial cells isolated from chicken jejunum: an experimental model for the study of the functional properties of amino acid transport system b(0,+).

The transport of lysine has been investigated in epithelial cells isolated from chicken jejunum. The kinetics of lysine transport and the pattern of interaction with zwitterionic amino acids were consistent with system b(0,+) activity, the broad-spectrum and Na(+)-independent amino acid transporter. The half-saturation constant for lysine entry (K(m)+/-S.E.) was 0.029+/-0.002 mM and the flux was not affected significantly by Na(+) replacement with choline. Lysine influx was inhibited by L-leucine both in Na(+) and choline medium with inhibition constants (K(i)+/-S.E.) 0.068+/-0.006 mM (in Na(+)) and 0.065+/-0.009 mM (in choline). Other inhibitory amino acids (K(i)+/-S.E.) were (mM): L-tyrosine (0.073+/-0.018), L-methionine (0.15+/-0.015), L-cystine (0.42+/-0.04), L-cysteine (1.1+/-0.07), L-isoleucine (1.1+/-0.09), L-glutamine (1.8+/-0.16) and L-valine (2.5+/-0.13). Lysine exit was trans-accelerated (approx. 20 fold) by 2 mM L-lysine and L-leucine. The flux was resistant to pretreatment of the cells with p-chloromercuriphenylsulfonate (0.2 mM), which is an inhibitor of system y(+)L, the broad-spectrum and cation-modulated transporter.

Mammalian amino acid transport system y+ revisited: specificity and cation dependence of the interaction with neutral amino acids.

A reevaluation of the specificity of system y+, the classical transporter for cationic amino acids is presented. System y+ has been defined as a transporter for cationic amino acids that binds neutral amino acids with lower affinity in the presence of Na+. The discovery of other transporters for cationic amino has suggested that some properties, originally attributed to system y+, may relate to other transport systems. Uncertainty concerns mainly, the affinity for neutral amino acids and the cation dependence of this interaction. Neutral amino acids (13 analogues tested) were found to bind to system y+ in human erythrocytes with very low affinity. Inhibition constants (Kiy, mm) ranged between 14.2 mm and >400 mm, and the strength of interaction was similar in the presence of Na+, K+ or Li+ (145 mm). In choline medium, no interaction was detected up to 20 mm of the neutral amino acid. Guanidinium ion (5 mm, osmolarity maintained with choline) potentiated neutral amino acid binding; the effect was most important in the case of l-norvaline which aligned with guanidinium ion is equivalent to arginine. This suggests cooperative interaction at the substrate site. The specificity of system y+ was shown to be clearly distinct from that of system y+L, a cationic amino acid transporter that accepts neutral amino acids with high affinity in the presence of Na+ and which influenced the classical definition of system y+.

Immune response to three doses of quadrivalent rotavirus vaccine: 1-year follow-up.

Twenty-eight children who received three doses of the quadrivalent rotavirus vaccine with 4 x 10(5) plaque-forming units (p.f.u.) were followed during a year after vaccination. Serum samples were obtained and evaluated for rotavirus IgA and neutralizing antibodies against vaccine and human rotavirus strains. At the end of the study, up to 61% of the children showed an increase in circulating IgA antibody levels. Nearly all of the vaccinated children increased their neutralizing antibody titres against the vaccine strains, and 25-54% against human rotavirus serotypes. After comparing the vaccinees with a population of children naturally infected with serotype G1 in the same study area, we conclude that three doses of 4 x 10(5) p.f.u. of the quadrivalent vaccine should prepare the child against future severe rotavirus diarrhea.

Norwalk virus infection in Venezuela.

The presence of antibodies against Norwalk virus (NV) was studied in sera from different Venezuelan populations, using an enzyme immuno-assay (EIA) based on recombinant NV protein. Antibodies to NV were found in 47%-53% of urban subjects from Caracas, 83% of rural subjects from the west of the country, and 73%-93% of Amerindian subjects. The prevalences found in the rural and Amerindian groups were significantly higher than that in the urban group. Although about 50% of the children studied were seropositive for NV by the age of 5 years, only four (0.4%) of 1120 faecal samples from children with diarrhoea which were tested for the presence of NV antigen by sandwich EIA were found positive. An increase of at least 4-fold in the titre of anti-NV IgA was found in three (5%) of 61 pairs of sera taken during and 1 month after an acute episode of diarrhoea not due to rotavirus. NV was therefore not a predominant aetiological cause of gastro-enteritis in young children in Venezuela between 1993 and 1995, although it can be the cause of diarrhoea in infants.

System y+L: the broad scope and cation modulated amino acid transporter.

The properties are discussed of system y+L, a broad scope amino acid transporter which was first identified in human erythrocytes. System y+L exhibits two distinctive properties: (a) it can bind and translocate cationic and neutral amino acids, and (b) its specificity varies depending on the ionic composition of the medium. In Na+ medium, the half-saturation constant for L-lysine influx was 9.5 +/- 0.67 microM and the inhibition constant (Ki) for L-leucine was 10.7 +/- 0.72 microM. L-Leucine is the neutral amino acid that binds more powerfully, whereas smaller analogues, such as L-alanine and L-serine interact less strongly (the corresponding inhibition constants were Ki,Ala, 0.62 +/- 0.11 mM; Ki,Ser, 0.49 +/- 0.08 mM). In the presence of K+, the carrier functions as a cationic amino acid specific carrier, but Li+ is able to substitute for Na+ facilitating neutral amino acid binding. The effect of the inorganic cations is restricted to the recognition of neutral amino acids; translocation occurs at similar rates in the presence of Na+, K+ and Li+. The only structural feature that appears to impair translocation is bulkiness and substrates with half-saturation constants differing by more than 100-fold translocate at the same rate. This suggests that translocation is largely independent of the forces of interaction between the substrate and the carrier site. System y+L activity has been observed in Xenopus laevis oocytes injected with the cRNA for the heavy chain of the 4F2 human surface antigen. 4F2hc is an integral membrane protein with a single putative membrane-spanning domain and it remains to be clarified whether it is part of the transporter or an activator protein.

Efficacy of the rhesus rotavirus-based quadrivalent vaccine in infants and young children in Venezuela.

BACKGROUND: Rotaviruses are the principal known etiologic agents of severe diarrhea among infants and young children worldwide. Although a rhesus rotavirus-based quadrivalent vaccine is highly effective in preventing severe diarrhea in developed countries, in developing countries its efficacy has been less impressive. We thus conducted a catchment study in Venezuela to assess the efficacy of the vaccine against dehydrating diarrhea. METHODS: In this randomized, double-blind, placebo-controlled trial, 2207 infants received three oral doses of the quadrivalent rotavirus vaccine (4x10(5) plaque-forming units per dose) or placebo at about two, three, and four months of age. During approximately 19 to 20 months of passive surveillance, episodes of gastroenteritis were evaluated at the hospital. RESULTS: The vaccine was safe, although 15 percent of the vaccinated infants had febrile episodes (rectal temperature, > or =38.1 degrees C) during the six days after the first dose, as compared with 7 percent of the controls (P<0.001). However, the vaccine gave 88 percent protection against severe diarrhea caused by rotavirus and 75 percent protection against dehydration, and produced a 70 percent reduction in hospital admissions. Overall, the efficacy of the vaccine against a first episode of rotavirus diarrhea was 48 percent. Horizontal transmission of vaccine virus was demonstrated in 15 percent of the vaccine recipients and 13 percent of the placebo recipients with rotavirus-positive diarrhea. CONCLUSIONS: In this study in a developing country, the quadrivalent rhesus rotavirus-based vaccine induced a high level of protection against severe diarrheal illness caused by rotavirus.

Monoclonal antibody affinities of structurally related modified nucleosides.

A scale of relative affinities of a series of 2'-deoxycytidine and cytidine (CD) derivatives was established based on the data of cross-reactivities of these compounds as well as the displacements obtained from a competitive ELISA. No correlation could be established between the nucleosides modifying structures and the affinities. This can be explained by the possibilities of the modifying structures of intra- and intermolecular nonimmunospecific interactions owing to their degree of functionalization.

Homotypic immune response to primary infection with rotavirus serotype G1.

Some aspects of rotavirus humoral immunity were assessed on the basis of distinguishing serotype-specific specificities (VP4/VP7) by using rotavirus reassortants, human and animal strains in neutralization assays in serum samples obtained during the acute phase, and 1, 6 and 12 months after primary natural infection. In this study, all the infecting virus strains were characterized as G type and some also as P type. Primary natural infection induces a significantly greater homotypic neutralization response than heterotypic response. In addition, there was no significant difference in the number of homotypic or heterotypic responses following reinfection. Transplacentally acquired homotypic antibodies were associated with protection against dehydration during rotavirus gastroenteritis.

Evaluation of chemiluminescent detection of bromodeoxyuridine-labeled DNA.

Colorimetric immunoenzymatic procedures using monoclonal antibodies to detect 5-bromo-2-deoxy-uridine-DNA in hybridization experiments are not sensitive enough. We have developed a chemiluminescent immunodot assay to improve the sensitivity of the immunoenzymatic procedure, and attained a suitable detection level for single-stranded DNA. This new chemiluminescent immunodot assay has also been used to detect our recently synthesized cytidine analogue by means of its corresponding monoclonal antibody.

Molecular weight and kinetic parameters of DNA undergoing pulsed field gel electrophoresis.

Functions relating DNA size to reorientation time (Tr) should improve the theoretical basis to design pulsed field gel electrophoresis experiments. We initially developed a quantitative approach to calculate Tr based on kinetic data: DNA migration per pulse (d), and pulse time duration. Using this procedure with some modifications and a computer controlled pulsed field electrophoresis switching unit, we obtained the Trs of several DNA molecules of known molecular weight and analyzed the functional dependence between these parameters. The function obtained was used to interpolate the Tr values of yeast (Saccharomyces cerevisiae) chromosomes. We also interpolated the sizes of yeast chromosomes I and VI, and compared them with those obtained by another independent method, using lambda-mers and polynomial functions relating lambda-mers migration and DNA sizes. The equation obtained should be useful to separate chromosomes by PFGE and to study the genomes of microorganisms, parasites and mammals. (Arch Med Res 1994; 25:193).

Grand mal seizure and clobutinol overdose.

We report the case of a previously healthy girl who developed a grand mal seizure after an inappropriate dose of clobutinol and had a good response to iv diazepam.

Modelo paramétrico para el análisis de potenciales relacionados a eventos múltiples / Parametric model for the analysis of potentials related to multiple events

En este trabajo se presenta un método para la estimación de los potenciales relacionados a eventos (PRE) contenidos en segmentos de electroencefalograma (EEG). El modelo presupone que en el dominio del tiempo los potenciales relacionados a eventos múltiples (PREM) se superponen aditivamente. Cada componente es de morfología constante pero su amplitud y latencia pueden variar. Se presenta un algoritmo máximo verosímil para la estimación de la forma de onda de cada componente que utiliza una estimación a priori de sus latencias. El algoritmo fue valiado con PREM simulados por computadora y utilizado en la descripción de potenciales evocados auditivos de tallo cerebral de humanos y potenciales evocados auditivos de latencia media de humanos y primates