Mercuric chloride effects on rat renal redox enzymes activities: SOD protection

This study was done to determine the effect of mercuric chloride treatment on the redox cycle enzymes in rat kidney ex-vivo. Glutathione peroxidase (GSH-Px) and catalase (Cat) activities were measured in kidney homogenates from rats with different nonprotein sulfhydrils levels and different mercury content. The results indicated that GSH-Px activity was enhanced in mercury-treated rats in direct relationship with kidney mercury content, whereas Cat activity was increased in the presence of the highest mercury kidney content obtained. Superoxide dismutase (SOD) was administered to rats prior to mercury chloride injection and renal function, development of lipid peroxidation and renal glutathione level were measured 1 h later. Renal function, renal glutathione, and renal lipid peroxidation production were maintained similar to control values. Moreover, SOD pretreatment also protected kidney from mercuric chloride histological alterations observed 24 h post mercury treatment. Thus, an inhibition of renal redox cycle enzymes "in vivo," did not appear to be an important determinant of the increased lipid peroxidation observed during mercuric chloride nephrotoxicity.

[Anesthesia with isoflurane in air and with isoflurane and nitrous oxide]

BACKGROUND

The aim of this study is to control the depth, the quality of recovery of total inhalation isoflurane anesthesia with or without nitrous oxide.

DESIGN

Controlled comparative study was carried out on 51 patients, aged 40-54 yr, ASA 1, undergoing saphenectomy, in an University Clinic.

METHODS

Induction: thiopental (3.5 mg kg), atracurium (0.6 mg kg) i.v. Patients were randomly assigned to: group 1 (26 patients), 5% isoflurane in air, by mask; group 2 (25 patients), 3% isoflurane and 60% N2O, by mask. Maintenance: group 1, 2% isoflurane in air; group 2, 1.2% isoflurane and 60% N2O. During anesthesia, consciousness and analgesia level were monitored by EEG Compressed Spectral Array, and clinical signs of pain by Evans' test; arousal time evaluation by "Time to correct response test". The subjective impressions, eventual dreams and recalls were collected using a standard set of questions one hour after the end of anesthesia and 24 hours later. One hour before anesthesia and two hours after the end of surgical procedures, a psychomotor performance recovery evaluation was performed using Zazzo's "deux barrages" test.

DATA ANALYSIS

Student's "t" test.

RESULTS

Adequate anesthetic depth was documented in all patients. Recovery time was statistically longer in isoflurane group (group 1 16.7 sd 2.2 minutes vs 10.3 sd 1.9 minutes group 2, p < 0.01). No patient reported recalls relative to anesthetic period. Two hours after recovery no significant differences in psychomotor performance tests were recorded.

CONCLUSIONS

Isoflurane anesthesia in air, in adequate concentrations, provides a sufficient level of analgesia, hypnosis, amnesia, without clinical side effects.

[Effect of dopexamine in splanchnic perfusion during surgery of the abdominal aorta]

Abdominal aortic surgery has significant effects on cardiac and splanchnic perfusion. The purpose of this study was to examine the effects of dopexamine, an inodilator drug, on hemodynamic and splanchnic perfusion with measurement of gastric intramucosal pH, by the method of gastric tonometry, during abdominal aneurysm resection. Twenty-five patients undergoing excision of an aortic abdominal aneurysm were randomly divided into two groups. During aortic cross-clamping Group II patients received dopexamine infusion, at a dose of 1 microgram/kg/m, and at a dose of 0.5 micrograms/kg/m from declamping to the end of the surgery. Whereas Group I patients did not receive a dopexamine infusion. During aortic cross-clamping the intramucosal pH value decreased in Group I patients, but did not change in Group II patients. Heart rate, cardiac index, and mixed venous oxygen saturation increased significantly during dopexamine infusion, whereas systemic vascular resistance was reduced. During aortic cross-clamping dopexamine was a useful agent in improving splanchnic blood flow, cardiac index venous saturation. Also, since the drug produces dose related hemodynamic changes of rapid onset and reversibility, it is possible to interrupt the infusion before aortic declamping to avoid the decrease in the intramucosal pH value.

Effect of different renal glutathione levels on renal mercury disposition and excretion in the rat

Mercury renal disposition has been studied following HgCl2 injection (5.0 mg/kg body wt., s.c.) in controls, diethylmaleate and N-acetylcysteine-treated rats. The different treatments were used to generate statistically different degrees of non-protein sulfhydryls concentration in kidneys. Diethylmaleate (4 mmol/kg body wt., i.p.) diminished kidney glutathione levels to 25% and N-acetylcysteine (2 mmol/kg body wt., i.p.) increased kidney non-protein sulfhydryls levels up to 75% compared with new controls. The amount of mercury in the kidneys, the mercury excretion rate in urine and the mercury plasma disappearance curves were calculated during 3 h post HgCl2 injection. BUN was measured in plasma at the same time period to determine the onset of kidney damage. The results indicate a higher HgCl2 renal clearance in N-acetylcysteine-treated rats compared to controls and less renal mercury accumulation. The data agree with diminished renal toxicity. On the other hand, renal mercury accumulation was higher and mercury renal clearance lower in diethylmaleate-treated animals, associated with higher renal toxicity. The results suggest that non-protein sulfhydryl levels (principally glutathione) might determine renal accumulation of mercury as well as its elimination rate and hence might enhance or mitigate the nephrotoxicity induced by the metal.

Acetaminophen nephrotoxicity in male Wistar rats

Acute acetaminophen (APAP) nephrotoxicity was studied in male Wistar rats 1 h after different APAP single doses (200, 500 and 1000 mg/kg body wt, i.p.). Significant impairments in glomerular filtration rate (GFR) and clearance of p-aminohippuric acid (ClPAH) were observed in a dose-dependent way, although tubular parameters measured, water and electrolyte fractional excretion, remained at control values, while the urine to plasma osmolality ratios (Uosm/Posm) were diminished in APAP-1000 rats (control = 2.93 +/- 0.20, APAP-1000 = 1.40 +/- 0.04). The time course of renal function was also studied in APAP-1000 mg/kg-treated animals; parallel impairments were observed in GFR, ClPAH and tubular functions. Maximal alteration was observed at 16 h and restorement began at 24 h post-injection. Glucose renal handling, either at low or at high tubular glucose loads, remained at control values. Thus, our data suggest that the early stage of acetaminophen nephrotoxicity might be due to renal hemodynamic changes which might induce an alteration in tubular function principally in distal structures of medullary tissue, as shown by the Uosm/Posm results. These effects occurred coupled with a diminution in hepatic glutathione (GSH) levels at every APAP dose and in renal GSH levels in APAP-1000 mg/kg-treated rats. Moreover, renal damage was observed both in the presence or absence of hepatic damage.

Effectiveness of N-acetylcysteine in protecting against mercuric chloride-induced nephrotoxicity

Mercuric chloride (HgCl2)-induced nephrotoxicity, as measured by functional and biochemical parameters was evaluated in rats at different kidney non-protein sulfhydryls (NPS) levels. Diethylmaleate (DEM) induced a 75% of NPS diminution 1 h after the administration. Renal function (clearance) and biochemical measurements (gamma-glutamyltranspeptidase activity in urine, and lipoperoxides in kidney tissue) were impaired when the animals were HgCl2-treated. Values were highly impaired when the kidneys were NPS-depleted and were improved when NPS pools were previously increased although they were not similar to control values. DEM treatment promoted a higher accumulation of HgCl2 in both kidney and liver while NAC-treatment reduced significantly the metal content in these organs. These data are in favour of a positive relationship among mercury content and organ injury. On the other hand, mercury content increased while NPS levels diminished. NPS might play a role in the HgCl2 detoxification and thus avoids mercury accumulation and mercury effects.

[Tuberculin reaction in healthy infants vaccinated with BCG at birth]

Tuberculin test with PPD RT-23 with Tween 80 (2 TU strength), was performed to 228 infants under two years of age. None of them had any history of contact with tuberculosis. All were healthy, well-nourished infants, and had been vaccinated with BCG at birth. A positive PPD reaction (greater than 6 mm), was found only in 8.8%, of them and 16.2% had no BCG scar on examination; 14.9% of the studied infants had negative PPD (0-5 mm) reactions together with absent BCG scars. These findings are significantly different from those previously reported by chilean authors, which showed higher proportion of positive (greater than = 6 mm) reaction to 2 TU PPD in infants from similar populations that had been vaccinated with different BCG preparations than our patients. These results suggest the need to evaluate the efficacy of the BCG vaccines that are currently being used in our country to determine the factors that may affect it and the protection that they afford.

[Effects of extracorporeal circulation and hypothermia on cellular immune activity in patients undergoing heart surgery]

Aspecific cellular reactivity was assessed in patients who underwent open heart surgery. The authors conclude that depressed PMN activity measured as O2- production is not linked to anaesthesiological procedures, hemodilution and hypothermia. No conclusive reports are possible on the role of pulmonary reinfusion or plasmatic and cellular mechanism of depression.

[Therapy with ketotifen in breast-fed infants with asthma]

Fifty asthmatic infants under 10 months of age included in a double blind placebo controlled trial lasting nine months. The whole group received continuous bronchodilator therapy with fenoterol + ipratropium in the first month. This was gradually discontinued in the second month, and half of the children began to receive ketotifen 0.35 mg each 12 hours, and the other placebo. The treatment was maintained for months. During this period, both groups received bronchodilators only in the presence of wheezing attacks. Bronchodilator consumption, symptoms registered in a diary card, results of a medical examination practiced each 10 days, and symptoms/bronchodilator requirements relationship were considered in the evaluation. Both groups showed a significant reduction in their symptom after the continuous bronchodilator use period. Control group did not experience further improvement within the next months, despite raising bronchodilators use. Ketotifen group improved all parameters evaluated and diminished their bronchodilator consumption. These changes reached statistical significance after three months ketotifen treatment. In the follow-up posttreatment, ketotifen group remained with significative less symptoms (p less than 0.001).

Bronchodilator effect of fenoterol and ipratropium bromide in infants with acute wheezing: use of MDI with a spacer device

Twenty-eight infants admitted to Exequiel González Cortes Children's Hospital because of acute wheezing (AW) were randomly assigned to three study groups. Fenoterol (FNT), ipratropium bromide (IB), and placebo were administered respectively to children in the different groups by means of metered dose inhalers (MDI) with spacers, using doses of 3 puffs every hour, for 4 hours. The degree of bronchial obstruction was assessed clinically and scored with the single-blind method every hour prior to each treatment. The criterion of a bronchodilator effect was a significant decrease in the degree of bronchial obstruction at subsequent scorings. The scores of the three groups were compared using the Student's t test for matched samples. The same test was also applied to the independent samples for determining the superiority of one treatment, FNT or IB, over the other. The results indicated a significant decrease in the scores of the groups receiving FNT and IB (P less than 0.05); this did not occur in the group in which placebo was used. FNT produced a more rapid and sustained effect than IB (P less than 0.05). Significant bronchodilator effect was obtained in infants with AW when repeated doses of FNT or IB were administered with MDI and spacers. This effect was significantly greater in the group treated with FNT.

Use of nebulized bronchodilators in infants under 1 year of age: analysis of four forms of therapy

The main purpose of this study was to evaluate four different forms of treatment in young infants admitted for acute wheezing (AW). Seventy-nine infants less than one year of age were randomly assigned to one of five groups. Group 1 received nebulized fenoterol plus ipratropium bromide, group 2 fenoterol, group 3 fenoterol plus steroids, and group 4 aminophylline, IV, plus steroids and oral fenoterol; the control group, or group 5, received nebulized normal saline solution. Clinical evaluation was done by means of a scoring system. The effectiveness of treatments was estimated by a score decrease in the first 24 hours, by the percentage of patients whose scores did not decrease during the same period, and by the number of days in the hospital. All infants had significantly decreased scores, except those in the control group; the aminophylline group included a greater percentage of patients who did not abate their scores, and they stayed in the hospital for more days than those in the other groups. The fenoterol group had the shortest hospital stay. All four treatments produced objective clinical improvement in bronchial obstruction. However, the nebulized bronchodilator treatments were more effective than aminophylline IV in decreasing scores on the first day, and they resulted in shorter hospitalization.

Effects of nebulized fenoterol, associated with ipratropium or steroids, on the heart rate of infants under one year of age with acute wheezing

The main objective of this study was to evaluate the effect of fenoterol alone or associated with ipratropium bromide or steroid on the heart rate in young children. Ninety-four infants less than 1 year of age were randomly allocated to receive nebulized fenoterol alone, fenoterol plus ipratropium bromide, fenoterol plus corticosteroids, or normal saline solution. An increase in heart rate was observed in all four groups. The increases were statistically significant (P less than 0.001) in all three treatment groups, and no difference between them was observed (F = 0.65, NS). However, the heart rate remained within clinically acceptance limits. We conclude that nebulized fenoterol alone or combined with ipratropium or steroids can be safely used in the treatment of wheezy infants.