Anibal Llanos - Academia.edu (original) (raw)

Papers by Anibal Llanos

Journal of Biomechanics, 2023

PubMed, Apr 1, 1979

Plasma lecithin: cholesterol acyltransferase (LCAT) activity was studied in 100 normal full-term ... more Plasma lecithin: cholesterol acyltransferase (LCAT) activity was studied in 100 normal full-term newborn infants during the first few days of life. The present study shows that plasma LCAT activity present at birth-though at much lower levels than those in the maternal blood-undergoes a fall after birth followed by a rise. It is also shown that the activity of the plasma LCAT enzyme is not strictly linked to the esterification of plasma-free cholesterol in the first three days after birth. However, from the fourth day onwards, there was a good correlation between LCAT activity and esterification of plasma-free cholesterol. The results suggest that plasma LCAT in newborn infants could be partially derived from maternal sources.

PubMed, Sep 1, 1987

The existence of the ductus venosus in mammalian fetal liver determines a different blood flow in... more The existence of the ductus venosus in mammalian fetal liver determines a different blood flow in the right and left lobes. This asymmetry is associated to a decrease in oxygen delivery to the right lobe. Some stages in oxygen metabolism are related to the formation of free radicals that can induce cellular damage dependent on the tissue oxygen concentration and on the activity of the enzymatic and non enzymatic systems involved in the tissue protection. In the present study, the differences in the lipid peroxidative status and some parameters related to the protection against oxygen toxicity between both lobes in the sheep fetal liver were analyzed and compared to the same parameters in the dam liver.

The Journal of Pediatrics, Aug 1, 1976

Biology of Reproduction, Nov 1, 2021

Living at high altitudes and living with prostatic illness are two different conditions closely r... more Living at high altitudes and living with prostatic illness are two different conditions closely related to a hypoxic environment. People at high altitudes exposed to acute, chronic or intermittent hypobaric hypoxia turn on several mechanisms at the system, cellular, and molecular level to cope with oxygen atmosphere scarcity maintaining the oxygen homeostasis. This exposure affects the whole organism and function of many systems, such as cardiovascular, respiratory, and reproductive. On the other hand, malignant prostate is related to the scarcity of oxygen in the tissue microenvironment due to its low availability and high consumption due to the swift cell proliferation rates. Based on the literature, this similarity in the oxygen scarcity suggests that hypobaric hypoxia, and other common factors between these two conditions, could be involved in the aggravation of the pathological prostatic status. However, there is still a lack of evidence in the association of this disease in males at high altitudes. This review aims to examine the possible mechanisms that hypobaric hypoxia might negatively add to the pathological prostate function in males who live and work at high altitudes. More profound investigations of hypobaric hypoxia’s direct action on the prostate could help understand this exposure’s effect and prevent worse prostate illness impact in males at high altitudes.

Vascular Pharmacology, 2022

BACKGROUND Fetal chronic hypoxia is associated with blood flow redistribution and oxidative damag... more BACKGROUND Fetal chronic hypoxia is associated with blood flow redistribution and oxidative damage in the brain, leading to increased perinatal morbimortality. Melatonin reduces oxidative stress, improves vascular function, and has neuroprotective effects. OBJECTIVES This study aimed to determine the effects of an oral melatonin treatment to pregnant ewes at high-altitude, on the cerebrovascular function of their neonates. STUDY DESIGN Ten high-altitude pregnant sheep received either vehicle or melatonin (10 mg/d) during the last third of gestation until delivery. Postnatal daily hemodynamic measurements were recorded from lambs until 12 days old. In addition, lambs were submitted to a graded oxygenation protocol to assess cerebrovascular responses. Subsequently, lambs were euthanized, and middle cerebral arteries (MCA) were collected for vascular function, protein levels, and morphostructural analyses. RESULTS Antenatal treatment doubled plasma levels of melatonin in pregnant ewes. Melatonin increased carotid flow and decreased carotid vascular resistance in the lambs by the end of the first week. Furthermore, melatonin increased MCA's maximal vasoconstrictor and vasodilator responses, associated with nitric oxide-dependent and independent mechanisms. CONCLUSIONS An oral treatment with melatonin during pregnancy promotes postnatal cerebral perfusion in chronically hypoxic neonates. Melatonin is a potential treatment for cerebrovascular dysfunction due to perinatal chronic hypoxia.

not for the birds! Last Word on Point:Counterpoint: High altitude is/is You might find this addit... more not for the birds! Last Word on Point:Counterpoint: High altitude is/is You might find this additional info useful... 5 articles, 3 of which can be accessed free at:This article cites

Frontiers in Physiology, 2022

Calcium signaling is key for the contraction, differentiation, and proliferation of pulmonary art... more Calcium signaling is key for the contraction, differentiation, and proliferation of pulmonary arterial smooth muscle cells. Furthermore, calcium influx through store-operated channels (SOCs) is particularly important in the vasoconstrictor response to hypoxia. Previously, we found a decrease in pulmonary hypertension and remodeling in normoxic newborn lambs partially gestated under chronic hypoxia, when treated with 2-aminoethyldiphenyl borinate (2-APB), a non-specific SOC blocker. However, the effects of 2-APB are unknown in neonates completely gestated, born, and raised under environmental hypoxia. Accordingly, we studied the effects of 2-APB-treatment on the cardiopulmonary variables in lambs under chronic hypobaric hypoxia. Experiments were done in nine newborn lambs gestated, born, and raised in high altitude (3,600 m): five animals were treated with 2-APB [intravenous (i.v.) 10 mg kg–1] for 10 days, while other four animals received vehicle. During the treatment, cardiopulmona...

Frontiers in Physiology, 2021

The authors previously demonstrated that newborn llama (NBLL) express high levels of α1 adrenergi... more The authors previously demonstrated that newborn llama (NBLL) express high levels of α1 adrenergic receptors, which provide a potent vasoconstriction response when compared with newborn sheep (NBSH) gestated at sea level. However, data regarding the impact of chronic gestational hypobaric hypoxia on α-adrenergic vasoconstriction in the neonatal life has not been studied. We evaluated if gestation under chronic hypobaric hypoxia modifies α1-adrenergic vasoconstrictor function in NBLL and NBSH. We compared the vasoconstrictor response induced by potassium and α-adrenergic stimuli in isolated small femoral arteries of NBLL and NBSH gestated at high altitude (HA; 3,600 m) or low altitude (LA; 580 m). The maximal contraction (RMAX) and potency (EC50) to potassium, noradrenaline (NA), and phenylephrine (PHE) were larger in HA-NBLL than LA-NBLL. RMAX to potassium, NA, and PHE were lower in HA-NBSH when compared with LA-NBSH and potency results were similar. Competitive blockade with prazos...

Frontiers in Bioengineering and Biotechnology, 2020

Journal of Pineal Research, 2019

Frontiers in Endocrinology, 2019

Revista médica de Chile, 2019

Nitric Oxide, 2019

Nitric oxide (NO) is the main vasodilator agent that drives the rapid decrease of pulmonary vascu... more Nitric oxide (NO) is the main vasodilator agent that drives the rapid decrease of pulmonary vascular resistance for the respiratory onset during the fetal to neonatal transition. Nevertheless, the enhanced NO generation by the neonatal pulmonary arterial endothelium does not prevent development of hypoxic pulmonary hypertension in species without an evolutionary story at high altitude. Therefore, this study aims to describe the limits of the NO function at high-altitude during neonatal life in the sheep as an animal model without tolerance to perinatal hypoxia. We studied the effect of blockade of NO synthesis with l-NAME in the cardiopulmonary response of lowland (580 m) and highland (3600 m) newborn lambs basally and under an episode of acute hypoxia. We also determined the pulmonary expression of proteins that mediate the actions of the NO vasodilator pathway in the pulmonary vasoactive tone and remodeling. We observed an enhanced nitrergic function in highland lambs under basal conditions, evidenced as a markedly greater increase in basal mean pulmonary arterial pressure (mPAP) and resistance (PVR) under blockade of NO synthesis. Further, acute hypoxic challenge in lowland lambs infused with l-NAME markedly increased their mPAP and PVR to values greater than baseline, whilst in highland animals under NO synthesis blockade, these variables did not show additional increase in response to low PO2. Highland animals showed increased pulmonary RhoA expression, decreased PSer188-RhoA fraction, increased PSer311-p65-NFқβ fraction and up-regulated smooth muscle α-actin, relative to lowland controls. Taken together our data suggest that NO-mediated vasodilation is important to keep a low pulmonary vascular resistance under basal conditions and acute hypoxia at low-altitude. At high-altitude, the enhanced nitrergic signaling partially prevents excessive pulmonary hypertension but does not protect against acute hypoxia. The decreased vasodilator efficacy of nitrergic tone in high altitude lambs could be in part due to increased RhoA signaling that opposes to NO action in the hypoxic pulmonary circulation.

American journal of physiology. Regulatory, integrative and comparative physiology, Jun 24, 2016

Exposure to high-altitude chronic hypoxia during pregnancy may cause pulmonary hypertension in ne... more Exposure to high-altitude chronic hypoxia during pregnancy may cause pulmonary hypertension in neonates, as a result of vasoconstriction and vascular remodeling. We hypothesized that susceptibility to pulmonary hypertension, due to an augmented expression and activity of the RhoA/Rho-kinase (ROCK) pathway in these neonates, can be reduced by daily administration of fasudil, a ROCK inhibitor. We studied 10 highland newborn lambs with conception, gestation and birth at 3,600m in Putre, Chile. Five highland controls (HLC) were compared to 5 highland lambs treated with fasudil (HL-FAS; 3 mg kg(-1) day(-1), intravenously administered for 10 days). Ten lowland controls were studied in Lluta (50m; LLC). During the 10 days of fasudil's daily administration, the drug decreased pulmonary arterial pressure (PAP) and resistance (PVR), basally and during a superimposed episode of acute hypoxia. HL-FAS small pulmonary arteries showed diminished muscular area and a reduced contractile response...

Respiratory Physiology & Neurobiology, 2012