Brazilian journal of medical and biological research = Revista brasileira de pesquisas médicas e biológicas
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Braz. J. Med. Biol. Res. · May 2005
Cardiopulmonary bypass alters the pharmacokinetics of propranolol in patients undergoing cardiac surgery.
The pharmacokinetics of propranolol may be altered by hypothermic cardiopulmonary bypass (CPB), resulting in unpredictable postoperative hemodynamic responses to usual doses. The objective of the present study was to investigate the pharmacokinetics of propranolol in patients undergoing coronary artery bypass grafting (CABG) by CPB under moderate hypothermia. We evaluated 11 patients, 4 women and 7 men (mean age 57 +/- 8 years, mean weight 75.4 +/- 11.9 kg and mean body surface area 1.83 +/- 0.19 m(2)), receiving propranolol before surgery (80-240 mg a day) and postoperatively (10 mg a day). ⋯ In conclusion, increases in drug distribution could be explained in part by hemodilution during CPB. On the other hand, the increase of biological half-life can be attributed to changes in hepatic metabolism induced by CPB under moderate hypothermia. These alterations in the pharmacokinetics of propranolol after CABG with hypothermic CPB might induce a greater myocardial depression in response to propranolol than would be expected with an equivalent dose during the postoperative period.
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Improving the course and outcome of patients with acute respiratory distress syndrome presents a challenge. By understanding the immune status of a patient, physicians can consider manipulating proinflammatory systems more rationally. In this context, corticosteroids could be a therapeutic tool in the armamentarium against acute respiratory distress syndrome. ⋯ The major continuing problem is when to administer corticosteroids and how to monitor their use. The inflammatory mechanisms are continuous and cyclic, sometimes causing deterioration or improvement of lung function. This article reviews the mechanisms of action of corticosteroids and the results of experimental and clinical studies regarding the use of corticosteroids in acute respiratory distress syndrome.
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Braz. J. Med. Biol. Res. · Feb 2005
Effect of air pollution on pediatric respiratory emergency room visits and hospital admissions.
In order to assess the effect of air pollution on pediatric respiratory morbidity, we carried out a time series study using daily levels of PM10, SO2, NO2, ozone, and CO and daily numbers of pediatric respiratory emergency room visits and hospital admissions at the Children's Institute of the University of Sao Paulo Medical School, from August 1996 to August 1997. In this period there were 43,635 hospital emergency room visits, 4534 of which were due to lower respiratory tract disease. The total number of hospital admissions was 6785, 1021 of which were due to lower respiratory tract infectious and/or obstructive diseases. ⋯ NO2 was positively associated with all outcomes. Interquartile range increases (65.04 microg/m3) in NO2 moving averages were associated with an 18.4% increase (95% confidence interval, 95% CI = 12.5-24.3) in emergency room visits due to lower respiratory tract diseases (4-day moving average), a 17.6% increase (95% CI = 3.3-32.7) in hospital admissions due to pneumonia or bronchopneumonia (3-day moving average), and a 31.4% increase (95% CI = 7.2-55.7) in hospital admissions due to asthma or bronchiolitis (2-day moving average). The study showed that air pollution considerably affects children's respiratory morbidity, deserving attention from the health authorities.
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Braz. J. Med. Biol. Res. · Jan 2005
Participation of ATP-sensitive K+ channels in the peripheral antinociceptive effect of fentanyl in rats.
We examined the effect of several K+ channel blockers such as glibenclamide, tolbutamide, charybdotoxin (ChTX), apamin, tetraethylammonium chloride (TEA), 4-aminopyridine (4-AP), and cesium on the ability of fentanyl, a clinically used selective micro-opioid receptor agonist, to promote peripheral antinociception. Antinociception was measured by the paw pressure test in male Wistar rats weighing 180-250 g (N = 5 animals per group). Carrageenan (250 microg/paw) decreased the threshold of responsiveness to noxious pressure (delta = 188.1 +/- 5.3 g). ⋯ The selective blockers of ATP-sensitive K+ channels glibenclamide (40, 80 and 160 microg/paw) and tolbutamide (80, 160 and 240 microg/paw) dose dependently antagonized the antinociception induced by fentanyl (1.5 microg/paw). In contrast, the effect of fentanyl was unaffected by the large conductance Ca2+-activated K+ channel blocker ChTX (2 microg/paw), the small conductance Ca2+-activated K+ channel blocker apamin (10 microg/paw), or the non-specific K+ channel blocker TEA (150 microg/paw), 4-AP (50 microg/paw), and cesium (250 microg/paw). These results extend previously reported data on the peripheral analgesic effect of morphine and fentanyl, suggesting for the first time that the peripheral micro-opioid receptor-mediated antinociceptive effect of fentanyl depends on activation of ATP-sensitive, but not other, K+ channels.
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Braz. J. Med. Biol. Res. · Oct 2004
Glutamatergic neurotransmission modulates hypoxia-induced hyperventilation but not anapyrexia.
The interaction between pulmonary ventilation (V E) and body temperature (Tb) is essential for O2 delivery to match metabolic rate under varying states of metabolic demand. Hypoxia causes hyperventilation and anapyrexia (a regulated drop in Tb), but the neurotransmitters responsible for this interaction are not well known. Since L-glutamate is released centrally in response to peripheral chemoreceptor stimulation and glutamatergic receptors are spread in the central nervous system we tested the hypothesis that central L-glutamate mediates the ventilatory and thermal responses to hypoxia. ⋯ Under normoxia, KYN (N = 5) or MCPG (N = 8) treatment did not affect V E or Tb compared to saline (N = 6). KYN and MCPG injection caused a decrease in hypoxia-induced hyperventilation (595 +/- 49 for KYN, N = 7 and 525 +/- 84 ml kg-1 min-1 for MCPG, N = 6; P < 0.05) but did not affect anapyrexia (35.3 +/- 0.2 for KYN and 34.7 +/- 0.4 masculine C for MCPG) compared to saline (912 +/- 110 ml kg-1 min-1 and 34.8 +/- 0.2 masculine C, N = 8). We conclude that glutamatergic receptors are involved in hypoxic hyperventilation but do not affect anapyrexia, indicating that L-glutamate is not a common mediator of this interaction.