Aureliano Hernández

Hypoxic ascites in broilers: a review of several studies done in Colombia.

In Bogotá, Colombia, broilers developed ascites due to pulmonary hypertension of hypoxic origin at 2638 m above sea level. This disease has tremendous economic impact in various countries of the world and is characterized by pulmonary hypertension, hypertrophy and hyperplasia of the right ventricle of the heart, increased hematocrit and hemoglobin values, and ascites. This entity appears to be influenced by management practices and by inability of broilers to adapt to high altitude.

Nitric Oxide Synthase Expression in the Endothelium of Pulmonary Arterioles in Normal and Pulmonary Hypertensive Chickens Subjected to Chronic Hypobaric Hypoxia

Abstract SUMMARY. To determine whether or not exposure to chronic hypoxia and subsequent development of pulmonary hypertension syndrome (PHS) induce alterations in endothelial nitric oxide (NO) production in broilers pulmonary vascular bed of broilers, we studied the expression of nitric oxide synthase enzyme in pulmonary endothelial cells by a nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase histochemical staining reaction. For this purpose, 60 broilers of three different ages (17, 30, and 42 days) were used. The animals were distributed in two groups: a) 30 healthy (nonhypertensive) broilers and b) 30 chicks with PHS. All broilers in group b had fewer NADPH-diaphorase-positive endothelial cells in arterioles than did the nonhypertensive broilers. These differences were highly significant (P < 0.01). These results demonstrate for, the first time in broilers, that hypoxia-induced pulmonary hypertension is associated with a decrease of endothelial-derived NO expression in pulmonary vessels.

Endothelial hyperpolarizing factor increases acetylcholine-induced vasodilatation in pulmonary hypertensive broilers arterial rings

Pulmonary arterial hypertension (PAH) develops as result of imbalances between endothelium derived vasoconstrictors and vasodilators. Pulmonary hypertensive broiler chickens (PHBs) are deficient in NO production and endothelin-1 (ET-1) excess. With respect to prostacyclin, it appears that it does not alter vascular pulmonary tone in broilers. However, the role of Endothelium-Derived Hyperpolarizing Factor (EDHF) in PAH in broilers has not been determined. The possible involvement of EDHF in acetylcholine (Ach) induced vasodilatation was studied in pulmonary arterial rings taken from PHB and non-pulmonary hypertensive broilers (NPHBs). Ach induced higher vasodilatation in PHB than in NPHB. This dilatation seems to be directly related to the degree of PAH. Ach derived vasodilatation was inhibited, in PBH but not in NPHB, by blocking EDHF action with K(+) or Apamin plus Charybdotoxin. It is proposed EDHF as an important vasodilator in the pulmonary arteries of PHB, which may play a compensatory role in PAH pathophysiology.

Endothelin-1 Molecular Ribonucleic Acid Expression in Pulmonary Hypertensive and Nonhypertensive Chickens

Four hundred 1-d-old Cobb broilers were distributed in 3 groups: group A comprised broilers maintained under natural hypobaric hypoxia (Bogotá, Colombia); group B comprised broilers under relative normoxia (Villavicencio, Colombia); and group C comprised broilers maintained at 460 m above sea level (Villavicencio, Colombia) from d 1 to 25 of age, and then moved to 2,638 m above sea level (Bogotá, Colombia). Broilers were designated as nonpulmonary hypertensive (NPHB) and pulmonary hypertensive (PHB), to estimate possible differences between them in the lung expression of endothelin 1 (ET-1) mRNA at 24 and 42 d of age. In group A, 12 NPHB and 12 PHB were used for determination of ET-1 mRNA expression at 42 d. In group B, nonPHB were found, and therefore, ET-1 mRNA expression was detected in 48 NPHB, 24 of them in each age group (24 and 42 d). In group C, only NPHB were encountered at 42 and 53 d, and ET-1 mRNA expression was determined at 42 d in 24 birds. The ET-1 mRNA levels of PHB of group A at 42 d were significantly higher than the correspondent ones in NPHB of groups A (P < 0.001) and C (P < 0.05) at the same age. No differences in ET-1 mRNA expression were encountered between NPHB of groups A and B at 42 d (P > 0.05). However, ET-1 mRNA expression was higher in group C than the correspondent one in NPHB of groups A and B at 42 d (P < 0.001). The present data suggest that ET-1 may play a major role in pulmonary hypertension pathophysiology. It is possible that chickens should be exposed to hypobaric hypoxia before d 24, as a requisite to develop pulmonary hypertension. These results might provide clues for future studies in pulmonary vasoconstriction and vascular remodeling.

Síndrome de hipertensión pulmonar ¿un origen genético en pollos de engorde?

At least 83 % of non-synonimous polymorphisms which are of the simple nucleotide type have been identified in high performance commercial birds, such as Broiler, Layer and Silkie. This has allowed the collection of information about the variation rate in the nucleotide sequence in the chicken genome. The abovementioned variation occurs at 5 x 10-3 intervals in the nucleotide chain. It is important to look for associations among those variations, related to key phenotype characters, such as disease resistance or susceptibility. An example is the pulmonary arterial hypertension in meat-type broilers, a syndrome which accounts for nearly 30 % of mortality. A step toward the identification of these associations has been implemented by using both molecular technologies and statistical models that allow the generation of quick results useful in the implementation of breeding and selection programs. The present document describes both, the methodology for sequencing the domestic chicken genome and the polymorphism identification within candidate genes of susceptible broiler chickens prone to develop hypoxic pulmonary hypertension. Current implications to increase the knowledge about native species genome related to the use of molecular genetics are also discussed.

Serum concentration of sex-steroids, endometrial expression of their receptors, and endometrial morphology during the estrous cycle in Bos taurus Criollo and crossbred cows

ABSTRACT Romosinuano (Romo) and Costeño con cuernos (CCC) are Bos taurus criollo breeds (adapted to the conditions of the tropics) that presented higher plasmatic Progesterone (P4) concentration during the luteal phase compared to non-adapted genotypes. The central hypothesis was that these P4 concentrations could modulate the uterine receptivity. Blood and endometrial biopsy samples were obtained on days 0, 5, 10, 15, and 20 of the estrous cycle (day 0 = estrus) of animals of different genotypes [Romo (n = 14), CCC (n = 14), and Crossbreed Brahman × Holstein (Cross, n = 13)]. Tissue-samples were used for morphometry and immunohistochemistry analyses. Data analyses were performed with Proc Mixed of SAS. The criollo breeds have higher P4 concentrations on days 5 and 15, higher values of superficial glandular area (all days) and density (days 0, 5, 10, and 15) than Cross cows (P < 0.05). ESR1 and PGR immunostaining were higher on days 0, 5, and 15 and on days 0 and 15, respectively for CCC and Romo when compared to Cross (P < 0.05). In conclusion, tropical adapted bovine breeds possess more receptive to embryo uterine environment than non-adapted breeds. This is mediated by a higher serum progesterone concentration, a strong P4 signaling, and greater developed uterine-gland morphology.

In vitro effect of endothelin-1 and nifedipine on pulmonary vascular contraction of pulmonary hypertensive and non-pulmonary hypertensive chickens

ABSTRACT Endothelin-1 (ET-1) is relevant to the pathogenesis of pulmonary arterial hypertension (PAH) in several species, including broiler chickens. In ET-1-induced vasoconstriction, L-type voltage-operated calcium channels (VOCCs) play a crucial role. In this study, the effect that ET-1 and the calcium channel blocker (CCB) nifedipine have on ET-1-induced vascular contraction in pulmonary artery rings of both, non-pulmonary hypertensive chickens (NPHC) and pulmonary hypertensive chickens (PHC), was evaluated. A significant increase response in ET-1 was observed for PHC vascular rings with respect to those of NPHC (p < .05). Incubation with 1 μM nifedipine did not completely reverse the contraction induced by 1 × 10−7 M ET-1 in both NPHC and PHC rings, suggesting the participation of additional calcium sources procured via influx through L-type VOCC. Nifedipine reduced, to a higher degree, the contraction induced by ET-1 in NPHC (50%) when compared with that observed in PHC rings (30.7%). Thus, the ET-1-induced vasoconstriction processes are more efficient in PHC, and the influx of calcium into the cell through the L-type VOCC is presumably only a fraction of the necessary calcium for ET-1-induced vasoconstriction. It is suggested that blocking calcium uptake through alternative pathways (receptor-operated calcium channels and storage-operated calcium channels) may produce a vasodilation effect of considerable therapeutic significance in PHC.

Vascular density, protein and mRNA expression of hypoxia-inducible factor 2alpha, vascular endothelial growth factor and its type 2 receptor in the yolk sac membrane of three- and four-day-old chicken embryos incubated at 355 and 1378 metres above sea level

Vascular density of the yolk sac membrane (YSM), protein and mRNA expression of hypoxia-inducible factor 2alpha (HIF-2α), vascular endothelial growth factor (VEGF-A) and its type 2 receptor (FLK-1) in the YSM were compared in subjects incubated at two different altitudes: 355 and 1378 metres above sea level (masl) in Colombia. On days 3 or 4 of incubation, higher vascular density of YSMs (p<0.05 both of the days), relative expression of HIF-2α mRNA (p<0.01 and p<0.001 days 3 and 4, respectively), VEGF-A mRNA (p<0.01 and p<0.001 days 3 and 4, respectively) and FLK-1 mRNA (p<0.001 and p<0.0001 day 3 and 4, respectively) were encountered in embryos incubated at 1378 masl as compared to those incubated at 355 masl. Information is presented about immunoexpression of HIF-2α, VEGF-A and its receptor FLK-1 in the endoderm, mesoderm and ectoderm in the YSM on days 3 and 4, and it is demonstrated that endothelial cells in the YSM on day 3 of incubation express HIF-2α, which had not been previously reported.

Hypoxic Pulmonary Arterial Hypertension in the Chicken Model

The incidence and clinical evolution of PH in various strains of commercial chickens maintained under a natural hypoxic tropical environment in the Bogota plane at 2638 m above sea level (masl) have been evaluated over several years, using direct observation of animals, electrocardiography, morphometric studies, hematocrit and hemoglobin changes, histochemical, immunohistochemical and molecular procedures.