Exploring Chihuahuan Desert diversification in the gray-banded kingsnake, Lampropeltis alterna (Serpentes: Colubridae).

Within many biomes, the cause of phylogeographic structure remains unknown even across regions throughout North America, including within the biodiverse Chihuahuan Desert. For example, little is known about population structure or the timing of diversification of Chihuahuan endemics. This is due largely to the lack of population genomic studies within this region. We generated ultra-conserved element data for the gray-banded kingsnake (Lampropeltis alterna) to investigate lineage divergence and historical demography across the Chihuahuan Desert. We found three unique lineages corresponding to the Trans-Pecos and Mapimian biogeographic regions of the Chihuahuan Desert, and a distinct population in the Sierra Madre Occidental. Using several mutation rates to calibrate the timing of divergence among these lineages, we show that lineage divergence likely occurred during the Pleistocene, which indicates that careful consideration needs to be used when applying mutation rates to ultra-conserved elements. We suggest that biogeographic provinces within the Chihuahuan Desert may have served as allopatric refugia during climatic fluctuations of the Quaternary. This work serves as an important template for further testing biogeographic hypotheses within the region.

Cryptic diversity in the Mexican highlands: Thousands of UCE loci help illuminate phylogenetic relationships, species limits and divergence times of montane rattlesnakes (Viperidae: Crotalus).

With the continued adoption of genome-scale data in evolutionary biology comes the challenge of adequately harnessing the information to make accurate phylogenetic inferences. Coalescent-based methods of species tree inference have become common, and concatenation has been shown in simulation to perform well, particularly when levels of incomplete lineage sorting are low. However, simulation conditions are often overly simplistic, leaving empiricists with uncertainty regarding analytical tools. We use a large ultraconserved element data set (>3,000 loci) from rattlesnakes of the Crotalus triseriatus group to delimit lineages and estimate species trees using concatenation and several coalescent-based methods. Unpartitioned and partitioned maximum likelihood and Bayesian analysis of the concatenated matrix yield a topology identical to coalescent analysis of a subset of the data in bpp. ASTRAL analysis on a subset of the more variable loci also results in a tree consistent with concatenation and bpp, whereas the SVDquartets phylogeny differs at additional nodes. The size of the concatenated matrix has a strong effect on species tree inference using SVDquartets, warranting additional investigation on optimal data characteristics for this method. Species delimitation analyses suggest up to 16 unique lineages may be present within the C. triseriatus group, with divergences occurring during the Neogene and Quaternary. Network analyses suggest hybridization within the group is relatively rare. Altogether, our results reaffirm the Mexican highlands as a biodiversity hotspot and suggest that coalescent-based species tree inference on data subsets can provide a strongly supported species tree consistent with concatenation of all loci with a large amount of missing data.

Morulustatin, A Disintegrin that Inhibits ADP-Induced Platelet Aggregation, Isolated from the Mexican Tamaulipan Rock Rattlesnake (Crotalus lepidus morulus).

The Tamaulipan rock rattlesnake (Crotalus lepidus morulus) is a montane snake that occurs in the humid pine-oak forest and the upper cloud forest of the Sierra Madre Oriental in southwestern Tamaulipas, central Nuevo Leon, and southeastern Coahuila in Mexico. Venom from this rattlesnake was fractionated by High-Performance Liquid Chromatography for the purpose of discovering disintegrin molecules. Disintegrins are non-enzymatic, small molecular weight peptides that interfere with cell-cell and cell-matrix interactions by binding to various cell receptors. Eleven fractions were collected by anion exchange chromatography and pooled into six groups (I, II, III, IV, V, and VI). Proteins of the six groups were analyzed by SDS-PAGE and western blot using antibodies raised against a disintegrin. The antibodies recognized different protein bands in five (II, III, IV, V, and VI) of six groups in a molecular mass range of 7 to 105 kDa. Western blot analysis revealed fewer protein bands in the higher molecular mass range and two bands in the disintegrin weight range in group II compared with the other four groups. Proteins in group II were further separated into nine fractions using reverse phase C18 chromatography. Fraction 4 inhibited platelet aggregation and was named morulustatin, which exhibited a single band with a molecular mass of approximately 7 kDa. Mass spectrometry analysis of fraction 4 revealed the identification of disintegrin peptides LRPGAQCADGLCCDQCR (MH+ 2035.84) and AGEECDCGSPANCCDAATCK (MH+ 2328.82). Morulustatin inhibited ADP-induced platelet aggregation in human whole blood and was concentration-dependent with an IC50 of 89.5 nM ± 12.

Comparison of venom composition and biological activities of the subspecies Crotalus lepidus lepidus, Crotalus lepidus klauberi and Crotalus lepidus morulus from Mexico.

The rock rattlesnakes Crotalus lepidus comprise a group (lepidus, klauberi, morulus and maculosus) of poorly known mountain cold-tolerant snakes in Mexico. In particular, Crotalus lepidus morulus is a snake endemic of the northeast of Mexico, whereas Crotalus lepidus klauberi and C. l. lepidus are distributed in some regions of the north and central Mexico and southern U. S. Until now very little data are available from C. lepidus subspecies from Mexico, as the terrain inhabited by these snakes is generally steep and rugged. In this work, we have determined some biochemical and biological properties of C. l. morulus, C. l. klauberi and C. l. lepidus crude venoms. Some minor differences in venoms were noted in SDS-PAGE, HPLC profile and MALDI-TOF mass spectrometry analysis. Partial sequences of metalloproteinases, phospholipases A2 (PLA2) and galactose-specific lectins were identified in the venoms. Venoms of C. l. klauberi and C. l. lepidus had significantly higher hemorrhagic and lethal activities than C. l. morulus venom. Proteolytic activity in azocasein was higher in C. l. morulus venom, whereas gelatin hydrolysis was higher in C. l. klauberi. Fibrinogenolytic and PLA2 activities were very similar in all venoms tested. The histological observations in the gastrocnemius muscle damaged by venoms from all the subspecies confirmed myonecrotic and hemorrhagic activities (at 3 and 24 h), which resulted in a poor regenerative response after 14 days. However, C. l. lepidus and C. l. klauberi venom induced a higher increase in the plasma activity of creatine kinase (CK), evidencing higher myotoxicity, whereas paw edema-inducing activity was higher in C. l. lepidus venom. The results indicate that the venoms from the three subspecies have similar protein profiles in electrophoresis, HPLC and molecular weight determinations. However, differences were found in the biological activities in mice. Notably, the venoms of C. l. lepidus and C. l. klauberi present higher toxicity (lower LD50) and hemorrhagic activity than C. l. morulus venom.

Pollution biomarkers in the spiny lizard (Sceloporus spp.) from two suburban populations of Monterrey, Mexico.

Environmental pollution may severely impact reptile species in urbanized areas. The magnitude of the impact is analyzed in the present study using lizard tail tips for the quantitative evaluation of enzymatic biomarkers of pollution. Spiny lizards (Sceloporus serrifer and S. torquatus) were collected from two suburban localities in the Monterrey metropolitan area, Mexico: Chipinque Ecological Park, a natural protected area, and El Carmen Industrial Park (IP), a highly polluted site. Different enzymes were used as biomarkers including: acetylcholinesterase (AChE), butyrylcholinesterase (BChE), carboxylesterase (CaE), alkaline phosphatase (ALP), acid phosphatase (ACP), superoxide dismutase (SOD) and glutathione S-transferase (GST). The levels of AChE, BChE and ACP activity were not significantly different between localities. AChE and BChE, commonly used as biomarkers of neurotoxic polluting agents (e.g. organophosphate pesticides) do not appear to be affecting the populations from the study locations. In contrast, the levels of CaE, GST, ALP and SOD were significantly different between the localities. These biomarkers are regularly associated with oxidative stress and processes of detoxification, and generally indicate pollution caused by heavy metals or hydrocarbons, which are common in industrial sites. The data resulting from the analysis of these biomarkers indicate that these polluting agents are affecting the populations of Sceloporus in IP. The present work validates the possibility of conducting additional ecotoxicological studies using biomarkers in combination with a nondestructive sampling technique in species of spiny lizards that are abundant in many North America areas.

A multilocus perspective on the speciation history of a North American aridland toad (Anaxyrus punctatus).

Interpretations of phylogeographic patterns can change when analyses shift from single gene-tree to multilocus coalescent analyses. Using multilocus coalescent approaches, a species tree and divergence times can be estimated from a set of gene trees while accounting for gene-tree stochasticity. We utilized the conceptual strengths of a multilocus coalescent approach coupled with complete range-wide sampling to examine the speciation history of a broadly distributed, North American warm-desert toad, Anaxyrus punctatus. Phylogenetic analyses provided strong support for three major lineages within A. punctatus. Each lineage broadly corresponded to one of three desert regions. Early speciation in A. punctatus appeared linked to late Miocene-Pliocene development of the Baja California peninsula. This event was likely followed by a Pleistocene divergence associated with the separation of the Chihuahuan and Sonoran Deserts. Our multilocus coalescent-based reconstruction provides an informative contrast to previous single gene-tree estimates of the evolutionary history of A. punctatus.

Hipertensión arterial en el adulto mayor / Hypertension in the elder

El presente trabajo se efectuó con el objeto de realizar un estudio prospectivo, comparativo y descriptivo, sobre la frecuencia de la hipertensión arterial en nuestro medio. Se conformaron dos grupos de sujetos: menores de 60 años (grupo I) y mayores de 60 (grupo II). Se detectaron 150 pacientes (30 por ciento) con hipertensión arterial entre 500 sujetos mayores de 60 años; y 90 (13 por ciento) en 700 individuos menores de 60 años. No se encontraron diferencias estadísticamente significativas durante el estudio. El 81 por ciento del grupo I y el 80 por ciento del grupo II tuvieron una respuesta favorable desde el inicio de su tratamiento hasta los cuatro meses que duró su evaluación

Infarto cerebral secundario a vasoespasmo por angiografía / Cerebral infraction following a vasospasm by angiography

En este estudio presentamos un caso de infarto cerebral secundario a la realización de una angiografía. Revisamos la fisiopatología, clasificación de la enfermedad vascular y se realiza una revisión del tratamiento del vasoespasmo cerebral

Tromboembolia pulmonar, estudio clínico / Pulmonar thromboembolism, a clinical study

El presente trabajo se efectuó con el objeto de realizar un estudio comparativo entre pacientes en cuanto a cuadro clínico, factores de riesgo, laboratorio, radiología,electrocardiograma y gammagrama perfusorio, así como para reconocer la fuente embolígena, y ubicar la tasa de morbimortalidad. Se detectaron 40 casos de TEP en un lapso de dos años; 50% correpondió a cada grupo etario, las diferencias significativas detectadas para los factores de riesgo con el método de la Chi cuadrada y la prueba exacta de Fisher correspondieron a las variables poliglobulia, reposo y obesidad en el caso del grupo II (los pacientes mayores de 60 años de edad). el elecrtocardiograma y radiología con valores normales en el grupo I (los menores de 60 años). la tasa de mortalidad fue de 27%; el 73% restante evolucionó satisfactoriamente.