SIDE EFFECTS OF TUBERCULOSIS TREATMENT WITH FIXED-DOSE COMBINATIONS.

This paper aimed to explore the therapeutic effect and safety of Fixed-dose Combinations (FDCs) on tuberculosis. A computer search was carried out to review the literature related to clinical randomized controlled trials (RCTs) and clinical controlled trails (CCTs) on the curative effect and safety of treating pulmonary tuberculosis with FDCs. The results demonstrated that, in the 22 studies examined, comparison of sputum negative conservation rate of treating smear-positive pulmonary tuberculosis with FDCs and single drug, the relative risk (RR) value and 95% confidence interval (CI) were 1.02 (1.01, 1.03) and 1.01 (1.00, 1.02), respectively, at the end of the 2nd month and 6th month (P<0.05), while comparison of the relapse rate within six months showed that RR value and 95% CI was 1.72 (0.98, 3.02) (P>0.05). No statistically significant differences were found between the two groups in total occurrence of the rates of side effects pertaining to skin reaction, gastrointestinal tract side reaction, occurrence rate of liver and gall side reaction or occurrence rate of drug withdrawal because of side effects (P>0.05). After sensitivity analysis, it was found that occurrence rate of gastrointestinal tract side effects and occurrence rate of liver and gall side effects were unstable. All the findings suggest that the curative effect of treating tuberculosis with FDCs is better than that of a single drug. More reliable evidence is required since the safety evaluation results are not stable.

Sulfonylurea receptor ligands modulate stretch-induced ANF secretion in rat atrial myocyte culture.

Stretch-induced atrial natriuretic factor (ANF) secretion was studied in cultures of neonate atrial appendage myocytes. Stretch, applied for 40 min by hypotonic swelling, increased the mean area of 44 individually imaged myocytes by 4.8-8.8% (P < 0.0001) at 6 min and by 2.3-6.2% (P < 0.05) at 35 min. Stretch increased immunoreactive ANF release by 42% (P < 0.05) from a baseline of 315 pg/ml. The ATP-sensitive K(+) (K(ATP))-channel blocker tolbutamide (100 micromol/l) increased the stretch-stimulated release to 84% (P < 0.01) over baseline, whereas lower concentrations (1, 10, and 30 micromol/l) had no stimulatory effect. The K(ATP)-channel opener diazoxide (0.1, 1, 10, 30, and 100 micromol/l) inhibited stretch- plus tolbutamide-stimulated ANF release in a concentration-dependent manner, with IC(50) = 2.2 micromol/l, although 100 micromol/l diazoxide did not reduce the increase in mean cell area. The stretch-stimulated K(ATP) current, monitored in 82 whole cell recordings with sulfonylurea receptor (SUR) ligands, was inversely correlated with the stretch-induced ANF release (r(2) = 0.79, P < 0. 0001). In the absence of stretch, the K(ATP) current had no relationship with baseline ANF release, and baseline ANF release was not affected by the K(ATP)-channel modulators. The results show that SUR ligands that open K(ATP) channels inhibit stretch-induced ANF release in atrial myocytes, in correlation with the stretch-activated K(ATP) current. The subcellular site of action of the SUR ligands-plasmalemma or intracellular organelles-remains to be determined.

Improved oxygenation after discontinuing neuromuscular blockade.

OBJECTIVE: To evaluate the effects of prolonged neuromuscular blockade (NMB) on oxygenation and duration of mechanical ventilation in children with respiratory failure. DESIGN: Retrospective case control study. SETTING: The pediatric intensive care unit (PICU) of a tertiary university hospital. PATIENTS: All children (n = 68) in the PICU ventilated for pulmonary parenchymal disease for 3 days or longer over a 4 1/2 year period. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Diagnoses, pediatric risk of mortality scoring, indications for, and duration of, mechanical ventilation and neuromuscular blockade, and blood gas data with corresponding ventilator parameters were extracted from the medical records. Twenty-eight patients received NMB at the initiation of mechanical ventilation and this was continued for 72 h or longer. Cessation of NMB was associated with a significant improvement in ventilator parameters and oxygenation index. The subset of children with respiratory syncytial virus disease (RSV) receiving prolonged NMB had longer ventilator courses compared to those in whom NMB was not used, despite similar demographics, severity of illness and oxygenation impairment. CONCLUSIONS: Stopping NMB is associated with a rapid improvement in oxygenation and prolonged use of NMB in children with RSV is associated with a protracted ventilatory course. DEFINITION: Oxygenation index (OI)*: Mean Airway Pressure x FiO2 x 100/PaO2* Higher scores represent deterioration in oxygenation.

ATP-sensitive potassium channels regulate stimulated ANF secretion in isolated rat heart.

Perfused hearts (n = 127) were exposed to acute hypoxia (10% O2 for 12 or 20 min) or left atrial stretch (increase in atrial pressure) in the presence or absence of 100 mumol/l ATP-sensitive potassium channel blocker (tolbutamide) or openers (pinacidil and diazoxide). Hypoxia alone elicited a prolonged atrial natriuretic factor (ANF) release, peaking at 74% over baseline (P < 0.01); with tolbutamide, ANF secretion peaked at 132% over baseline (P < 0.01). Pinacidil and diazoxide abolished the ANF response to hypoxia (P < 0.01). Atrial stretch alone (1 mmHg) transiently (2 min) increased ANF by 56% (P < 0.05); with tolbutamide, ANF increased transiently by 124% and showed a prolonged increase of 52% (P < 0.05). With tolbutamide, graded stretch (0.5-2.3 mmHg) induced a bell-shaped transient (2-min) increase of ANF release [-3% at 0.5 mmHg, 124% (P < 0.05) at 1.0 mmHg, 80% (P < 0.05) at 1.48 mmHg, and 14% at 2.22 mmHg] and a saturating prolonged ANF response. Tolbutamide increased the ANF response nonsignificantly at lower doses (30 mumol/l) and had no effect at 1 mumol/l. Pinacidil abolished the stretch-induced ANF release. These results suggest that ATP-sensitive potassium channels are extremely potent modulators of stimulated ANF secretion.

Calf's lung surfactant extract in acute hypoxemic respiratory failure in children.

OBJECTIVE: Open-label trial of the safety and short-term efficacy of calf's lung surfactant in pediatric respiratory failure. DESIGN: Multi-institutional, uncontrolled, observational trial. SETTING: Six pediatric intensive care units of tertiary medical centers. PATIENTS: Twenty-nine children with acute hypoxemic respiratory failure, characterized by diffuse, bilateral, pulmonary infiltrates, need for ventilator support, and an oxygenation index of > or = 7. INTERVENTIONS: Up to four doses of intratracheal surfactant (80 mL/m2). MEASUREMENTS AND MAIN RESULTS: Ventilator parameters, arterial blood gases, and derived oxygenation and ventilation indices were recorded before, and at intervals after, surfactant administration. Complications and outcome measures were also noted. There was immediate improvement in oxygenation and moderation of ventilator support associated with surfactant administration in 24 of 29 patients. A modest but statistically insignificant effect was seen with subsequent doses. The only complications occurred in three patients who developed airleaks, two of which were coincident with surfactant administration. The overall mortality rate was 14%, which compares favorably with other published series. CONCLUSIONS: Administration of calf's lung surfactant appears to be safe and is associated with rapid improvement in oxygenation and moderation of ventilator support in children with acute hypoxemic respiratory failure. These results set the stage for a randomized, controlled study.

Invasive monitoring in infants with respiratory syncytial virus infection.

OBJECTIVE: Coincident with a change in the physician staff in our pediatric intensive care unit (PICU), the frequency and duration of invasive monitoring were decreased. We examined the impact of this change on outcomes, complications, and hospital charges in infants admitted to the PICU with respiratory syncytial virus (RSV) infection. STUDY DESIGN: We reviewed medical records of all children less than 1 year of age who were admitted to the PICU from January 1989 to July 1993 with confirmed RSV infection. Patient characteristics, therapeutic interventions, outcomes, and hospital charges were extracted and compared. RESULTS: Seventy-eight patients were identified, 38 admitted from January 1989 through July 1991 (group 1) and 40 from July 1991 through July 1993 (group 2). The groups were well matched in age, preexisting disease, and cardiorespiratory status on admission. Group 1 had significantly greater use of invasive monitoring, pharmacologic paralysis, inotropes, blood products, antibiotics, and parenteral nutrition. Outcomes were not different, but group 1 patients had significantly longer stays, more complications, and higher hospital charges. CONCLUSIONS: Routine use of invasive monitoring of PICU patients with RSV disease was associated with increased laboratory testing, overtreatment, and significant increases in costs and morbidity without improvement in outcome.

Synergistic regulation of ANF in isolated rat hearts.

The interaction between cardiac sympathetic stimulation of atrial natriuretic factors (ANF) release and left atrial stretch was examined in groups (n = 5 or 6) of isolated, perfused (10 ml/min), paced rat hearts. Left atrial stretch, produced by an increase in atrial pressure of 1.1 +/- 0.2 mmHg over 8 min, transiently (4 min) increased ANF release by 46 +/- 4% over baseline (220 pg/ml buffer; P < 0.05). Infusion of 1 microM norepinephrine (NE) over 28 min caused a sustained increase in ANF release of 76 +/- 10% (P < 0.05). Atrial stretch plus NE caused additive effects on ANF release during stretch but 2.4 times the additive effects after stretch (P < 0.05). To examine whether resting tension modulates the ANF response to sympathetic stimulation, the left atrium was stretched throughout the experiment by increasing the atrial pressure by 1-1.5 mmHg. Infusion of 1 microM NE over 28 min increased ANF release by 216 +/- 46% (P < 0.01) in the prestretched heart, compared with a calculated summed increase of 85% due to NE alone plus prestretch alone. Infusion of 0.5 microM veratridine, known to stimulate ANF via mechanical effects on the heart, increased ANF release by 88 +/- 3% (P < 0.01). Scorpion venom, known to dose dependently stimulate ANF secretion via activation of neuronal sodium channels, elicits a negligible increase in ANF release at the threshold concentration of 0.1 microM. The combined infusion of 0.5 microM veratridine plus 0.1 microM venom increased ANF release by 239 +/- 53% (n = 6, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Neural control of the endocrine rat heart.

Although atrial stretch is the accepted stimulus for atrial natriuretic factor (ANF), in vivo studies suggest a stretch-independent, neurally induced ANF release mechanism. Thus the hypothesis that cardiac nerves can stimulate ANF secretion was tested in the Langendorff-perfused, paced rat heart. Venom from the scorpion Centruroides sculpturatus was used to activate neuronal sodium channels, veratridine was added to activate sodium channels (predominantly in myocytes), and electrical stimulation was applied to the right atrial appendage. The efficacy of nerve stimulation was verified by measurements of increased neuropeptide Y in the effluent. ANF levels in the effluent increased by 120% over baseline with 0.5 microM scorpion venom and by 88% with 0.5 microM veratridine (P < 0.01). Cardiac mechanics did not explain the large, concentration-dependent ANF response to the scorpion venom, since changes in the left ventricular developed pressure were small, opposite to those induced by veratridine, and unaffected by sympathectomy or adrenergic receptor blockade. Prior chemical sympathectomy and adrenergic receptor blockade almost abolished the ANF response to scorpion venom but hardly affected the ANF response to veratridine. Addition of 1 microM tetrodotoxin abolished all ANF responses. Electrical stimulation of the atrial appendage increased the ANF secretion by 60.2% (P < 0.02), in conjunction with neuropeptide Y, whereas control stimulations were ineffective. These studies unequivocally demonstrate that stimulation of cardiac sympathetic nerves potently stimulates ANF secretion.

Lower brain stem controls cardiac ANF secretion.

The purpose of these studies was to investigate whether the central nervous system (CNS) can modulate the plasma level of atrial natriuretic factor (ANF). In anesthetized, spontaneously breathing rats, electrical stimulation was stereotaxically applied bilaterally to four medullary nuclei: 1) the rostral nucleus of the solitary tract (rNTS), 2) the intermediate portion of the NTS (iNTS), 3) the ventrolateral nucleus ambiguus (NA) 0.3 mm rostral to obex, and 4) the rostral ventrolateral medulla (RVL). Electrical stimulation of the rNTS and RVL caused a 55 +/- 18% (P less than 0.025, n = 6) and 187 +/- 80% (P less than 0.001, n = 5) increase in plasma ANF, respectively, compared with baseline (56-88 pg/ml), whereas sham stimulations had no effect on plasma ANF release. In contrast, electrical stimulation of the iNTS and the NA elicited a 35 +/- 6 (P less than 0.01, n = 7) and 31 +/- 6% (P less than 0.05, n = 5) decrease in plasma ANF, respectively. In artificially ventilated rats, unilateral electrical stimulation of the RVL induced a 94 +/- 39 (left RVL, n = 6, P less than 0.01) and 186 +/- 68% (right RVL, P less than 0.01, n = 5) increase in plasma ANF over baseline. Unilateral microinjection of L-glutamate into RVL also resulted in a 81 +/- 23% (n = 9, P less than 0.01) increase in plasma ANF compared with baseline and vehicle control injections. These results suggest that activation of the central sympathetic system potently stimulates the secretion of cardiac ANF.

Neural control of ANF release in hypoxia and pulmonary hypertension.

Hypoxia causes the release of atrial natriuretic factor (ANF), but the mechanisms are not yet understood. This study examined the relative contribution of pulmonary arterial hypertension, neural pathways, increased heart rate, or increased atrial size to the ANF response. Alveolar hypoxia [fractional concentration of O2 in inspired gas (FIo2) = 0.1] or pulmonary arterial hypertension (25-45 mmHg) was induced for 10 min in four series (n = 4-12 each) of anesthetized, mechanically ventilated pigs. During hypoxia, plasma ANF concentrations increased by 129 +/- 52 (SE) pg/ml (or 271 +/- 105%) over baseline (35 +/- 7 pg/ml; P less than 0.01) (series 1). There was also a significant increase of pulmonary arterial pressure, heart rate, central venous pressure, and pulmonary capillary wedge pressure. Repeated pulmonary hypertension induced by intravenous air infusion caused a repeated and reversible 125 +/- 14% increase (P less than 0.001) of plasma ANF, and this response was totally abolished by lesion of the cervical vagosympathetic trunks (series 2). Lesion of these nerves 1 h before hypoxia also decreased the ANF response to hypoxia by 45-58% (P less than 0.01), whereas responses of heart rate and atrial pressures were unchanged (series 3). The ANF response to hypoxia, expressed in percent of baseline, was not affected by 0.2 mg/kg propranolol (PR) (no PR: 145 +/- 63%; PR: 151 +/- 82%; not significantly different from series 1 and control, series 3), although the increase in heart rate (no PR: 61 +/- 15 beats/min) was almost abolished (PR: 17 +/- 5 beats/min) (series 4). Hypoxia caused no significant changes in right and left atrial peak volume regardless of propranolol, as measured with an electrical conductance catheter. The results indicate that a new neural reflex of probably pulmonary arterial origin mediates approximately 50% of the ANF response to hypoxia. The remaining ANF response remains to be explored further and cannot be explained by conventional release mechanisms such as atrial stretch and pulsatility alone.