There is little information on the population status of the ocelot Leopardus pardalis in Mexico. In the Sierra Abra-Tanchipa Biosphere Reserve, in San Luis Potosí, ocelots are affected by habitat ...loss and fragmentation as a result of increased agricultural development. We used photographic identification in camera-trapping capture–recapture surveys to determine population abundance and density during the dry season and subsequent early and late humid seasons during April 2011–March 2012. We recorded 80 photographs of 15 individuals (10 males, one female, and four of undetermined sex) in 7,786 camera-days. Abundance was estimated using a closed capture heterogeneity model, yielding an estimated population of 9 ± SE 3 in the dry season and 21 ± SE 8 and 15 ± SE 5 during the subsequent early and late humid seasons, respectively. Spatially explicit density estimates were 0.04 and 0.03–0.18 individuals per km2 for the dry and humid seasons, respectively, and were similar (P > 0.612) among seasons. Peaks in ocelot activity occurred during 20.00–04.00. We conclude that the ocelots of the Sierra Abra-Tanchipa Reserve have a low population density and may face geographical and biological isolation as a result of habitat conversion. Continued monitoring and improved understanding of the movements and habitat preferences of ocelots are necessary to ensure their continued persistence, and connectivity between this population and others in north-east Mexico.
Siphonaptera are hematophage parasite vectors of both human and animal diseases. We aimed to identify ectoparasites parasitizing a coyote population (Canis latrans) in the northwest region of the ...Flora and Fauna Protection Area Médanos de Samalayuca, Chihuahua, Mexico. We captured 21 coyotes (15 males and 6 females) during the summer and winter of 2018. The individuals were anesthetized and thoroughly examined for ectoparasites. We found that 43% of the coyotes were infested. Based on characteristics such as the absence of pronotal and genal combs in the head, we identified 15 specimens as Pulex irritans. This is the first report of P. irritans in coyotes in Médanos de Samalayuca Chihuahua, Mexico.
•Siphonaptera are hematophage parasites globally distributed, with the exception of Antarctica and are vectors to important diseases.•Pulex irritans also known as the human flea is of great importance in public health and veterinary medicine.•Pulex irritans can transmit bacteria causing diseases of high relevance such as plague, borreliosis, and rickettsiosis.•This is the first report of P. irritans in Samalayuca Chihuahua, Mexico.
Background
Food protein‐induced enterocolitis (FPIES) is an uncommon, non‐IgE‐mediated food allergy that usually debuts in infancy with profuse vomiting, lethargy, and pallor 2–4 h following ...ingestion of the offending food. Its immune mechanism is not known. We aimed to describe the clinical features and outcome of children with fish‐FPIES as well as to investigate on cellular immune response implicated.
Methods
Prospective and follow‐up clinical study of children with FPIES by fish over a period between 2004 and 2013 was conducted. Measurement in vitro of both cytokine production in peripheral blood mononuclear cells (PBMCs) and expression of HLA‐DR in monocyte‐derived dendritic cells stimulated with fish extracts.
Results
Sixteen children (seven male and nine female) were included, with a mean age of onset at 10 months. Diagnosis was established after a median of 4 reactions. Twelve patients were treated in emergency room, and two were admitted in intensive care. Patch tests were positive in six patients. Skin prick tests (SPTs) and specific IgE to all fish tested were negative. Only three children reached tolerance at a mean age of 4.5 years. Eight children avoided fish because of positive oral food challenge (OFC) after 6 years of age. Other patients have not been challenged because of parent refusal to OFC or a recent diagnosis. TNF‐α was increased in patients, and a significant elevation of the HLA‐DR marker was also observed in these patients vs. control donors.
Conclusions
FPIES caused by fish in many cases presents with severe clinical manifestations. Patch test has poor diagnostic value, and OFC is the gold standard to test tolerance. The cytokine TNF‐α may be implicated in the clinical symptoms. Higher expression of HLA‐DR in dendritic cells has also been detected in our patients.
The stereoselective normal electron demand Diels−Alder reactions of chiral 1,2-diaza-1,3-butadienes, derived from acyclic carbohydrates having different configurations (1−6), with diethyl ...azodicarboxylate (DEAD) are disclosed. Reactions proceed slowly in benzene solution at room temperature, but are greatly accelerated by microwave irradiation to form the corresponding functionalized 1,2,3,6-tetrahydro-1,2,3,4-tetrazines (7−18) in good yields. The observed stereoselectivity is markedly dependent on the relative stereochemistry at C-1‘,2‘. Thus, 1,2-diazoalkenes derived from per-O-acylated sugars having threo configuration at C-1‘,2‘ give tetrazines with a high facial selectivity, whereas those having erythro configuration at C-1‘,2‘ afford products in lower diastereomeric ratios. The facial diastereoselection has been rationalized by a PM3 computational study. These results prove that in the transition structures (TSs) the reacting azoalkene exhibits formal negative charges at C-3 and N-2, the former being of greater magnitude, while the heterodienophile displays a partial positive charge at the substituent attached to the nitrogen atom. Accordingly, a stabilizing electrostatic interaction will only occur in TSs involving an endo orientation of the azodicarboxylate in its approach to the azadiene, a fact consistent with the experimental observations.
During the reproductive season of the white-tailed deer, 36 diluted semen samples from deer were evaluated before freezing, and at the time of thawing. The samples were obtained by electro ...ejaculation from three sedated deer with a mixture of Zoletil ® and xylazine hydrochloride. Samples were diluted with three commercial extenders Biladyl ®, Trilady ® and Bioxcell ® and frozen by applying two freezing curves, the one used for sheep and goat, and the recommended for deer semen. The response variable was the Semen Quality Index for Deer (SQID%) obtained from the estimation of the percentage of gross motility, progressive motility, alive sperms, normal sperms and sperm concentration. The results of the statistical analysis showed differences (p = 0.0301) between the extenders before freezing, resulting Bioxcell ® with greater SQID (60.77%), while for Triladyl ® and Biladil ® rates were 48.39% and 33.01%, respectively. As for the evaluated freezing curves, no differences were found (p = 0.5502) between the recommended curve for deer semen and the curve used for sheep and goat semen. In the present study, the use of the SQID as response variable turned out to be useful in the assessment of diluents and freezing curves.
The magnetic deshielding caused by the amido group on CON−CHα protons of secondary amides can easily be correlated with DFT-based structures at the B3LYP/6-31G* level of theory via a novel algorithm ...that refines previous models, such as the classical McConnell equation. The shift is given by δ = a + 2.16 cos2(α − 35)/d, where α denotes the virtual dihedral angle resulting from linking the carbonyl and the α-carbons and d is the distance (Å) between the shifted proton and the carbonyl oxygen. Notably, in this equation a is a parameter that can be optimized for different solvents, namely, CDCl3, DMSO-d 6, and D2O. For the development of these correlations, the preferential conformation of amides is taken from the optimized structures in the gas phase obtained at the DFT level. The deshielding on anti and gauche protons in both rotamers of (Z)-acetamides and E/Z isomers of formamides has been evaluated. This methodology has proved to be highly reliable, allowing us to discard ab initio or DFT conformational arrangements when shifts calculated by the above-mentioned equation differ from the experimental values. Thus, the anti disposition between the CHα proton and the N−H bond appears to be the more stable conformation of simple amides. For amides bearing only one proton at Cα, a local syn minimum can equally be characterized. The rotational barriers around the CON−alkyl bond along with the pyramidalization of the amido group have also been reassessed. As the conformation is taken away from anti or local syn minima, the nonplanarity of the amido group appears to increase.
The intermolecular 3 + 2 cycloaddition of carbohydrate-derived 1,2-diaza-1,3-butadienes and 1,3-thiazolium-4-olates provides a conceptual basis for the problem of diastereofacial preference in the ...acyclic series of unsaturated sugars. Experimental results employing a side chain of d-arabino configuration have shown the stereodifferentiation exerted by the first stereogenic center that renders the Re,Re face of the acyclic sugar-chain azadiene eligible for cycloaddition (J. Org. Chem. 2000, 65, 5089). The results of the present work, now utilizing an alternative framework of d-lyxo configuration, evidence the discriminating power of the second stereogenic carbon, which induces the preferential approach to the Re,Si face of the heterocyclic dipole. This scheme of face selectivity is also grounded in theoretical calculations at a semiempirical level. In addition to dihydrothiophenes, which are the expected products of the 3 + 2 cycloaddition, bicyclic systems based on dihydrothieno2,3-cpiperidine skeleton can also be obtained.
A series of highly funtionalized β-lactams and thiiranes can be generated on treatment of 1,3-thiazolium-4-olates (thioisomünchnones) with aliphatic aldehydes. Although in some cases a variety of ...products have been obtained, the present paper now provides a mechanistic rationale to explain the product distribution based on stereoelectronic effects. Thus, ring fragmentation of the initial 3+2 cycloadduct is essentially dictated by the electronic character of the aryl substituent on the nitrogen atom of the parent thioisomünchnone. However, further evolution of such cycloadducts into β-lactams or thiiranes is governed by steric effects to a large extent. Evidence for such interactions has been obtained by computing PM3-optimized diastereomeric transition structures in the reaction of a thioisomünchnone with a chiral aliphatic aldehyde.
A series of carbohydrate-based tetrahydropyridazines are prepared by the hetero-Diels−Alder reaction of the chiral 1,2-diaza-1,3-butadienes 1 and 2 with acrylonitrile. Reactions are regiospecific, ...and the observed diastereoselection is consistent with a preferred attack to the Re face of the heterodiene unit, as the chiral sugar placed at C4 does largely protect the opposite Si face. The stereochemistry of the major cycloadduct 4 has been firmly established by an X-ray crystallographic study that, in addition, reveals a conformation placing the cyano group in axial orientation. Cycloadducts such as 9 and 11, in which the axial cyano group and the carbohydrate moiety exhibit a cis relationship, undergo a facile E2 elimination that relieves the steric congestion. A detailed computational study is reported to provide better insight into the factors that influence this asymmetric cycloaddition. A DFT study (B3LYP/6-31G*) on a reduced model does correctly predict the regiochemistry observed experimentally, while the facial diastereoselection is modeled at a semiempirical (PM3) level on the parent reagents, thereby accounting for the steric factor provided by the chiral substituent. The calculations also indicate that the axial orientation of the cyano group can be rationalized in terms of a stabilizing anomeric effect.
A series of 2-(N-methyl)benzylamino-1,3-thiazolium-4-olates (2-aminothioisomünchnones) react with chiral 1,2-diaza-1,3-butadienes derived from carbohydrates to afford a diastereomeric mixture of ...(4R,5S)- and (4R,5R)-4,5-dihydrothiophenes. These substrate-controlled cycloadditions are chemoselective, regiospecific, and proceed with a high facial diastereoselection. A theoretical rationale at semiempirical level does justify the stereochemical outcome observed in the experiments.
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