Distribution of lead in lactating mice and suckling offspring with special emphasis on the mammary gland

The distribution of lead in lactating mice and suckling offspring was studied with whole body autoradiography at 4 and 24 h after a single intravenous injection of 203Pb (50 nmol Pb/kg) to the dams. In the lactating mice on day 14 of lactation, the highest uptake of radioactivity at 4 h after administration was recorded in renal cortex, skeleton and liver. A high uptake was also evident in the mammary gland. At 24 h after administration, the radioactivity had decreased in most organs except in the skeleton. In the suckling pups, exposed to lead only via dams' milk for 24 h, the highest level of radioactivity was present in the intestinal mucosa and a much lower level of radioactivity was present in the skeleton. The mammary glands from mice given three daily intravenous injections of 240 mumol Pb/kg were examined with X-ray microanalysis. At 4 h after the last injection, lead was found associated with casein micelles both inside the alveolar cell and in the milk lumen, indicating that lead is excreted into the milk, bound to casein, via the Golgi secretory system.     

Selenium and lead: mutual detoxifying effects

Antagonistic toxic effects of selenium and lead were studied in growing rats. Chronic lead intoxication was produced by cutaneous application of lead naphthenate solution (80-200 mg Pb/kg body weight) for a period of 8 weeks and chronic selenium intoxication was induced by giving 5 ppm, 10 ppm and 15 ppm selenium in drinking water. The growth rate and food consumption of rats receiving selenium in addition to lead approached normal rate while animals treated with only one of them showed hampered growth rate and lower food consumption. The enzymatic activity of delta-aminolevulinic acid dehydrase (ALA-D) in whole blood, liver and kidney and liver P-450 enzyme activity were normal in rats receiving both selenium and lead. The enzymic activities assayed were, however, depressed in the animals receiving either lead or selenium. Assay of lead and selenium in liver, brain, kidney and blood was carried out. Rats receiving both metals and higher concentrations of these metals in the organs studied, as compared to those only receiving one component. The data seem to indicate that the effect of selenium on the toxic effects of lead is similar to its protective role against methylmercury intoxication.     

Effect of 5-fluoroindole-2-carboxylic acid (an antagonist of the NMDA receptor-associated glycine site) on the anticonvulsive activity of conventional antiepileptic drugs

5-Fluoroindole-2-carboxylic acid, an antagonist of the glycine site within the NMDA receptor complex, administered intraperitoneally in doses of 150 and 200 mg/kg, 120 min before electroconvulsions, significantly raised the convulsive threshold from 6.8 to 7.9 and 8.3 mA, respectively. At lower doses, it did not influence the threshold. However, lethality was observed 24h after administration of the threshold-elevating doses of this glycine site antagonist. 5-Fluoroindole-2-carboxylic acid (100 mg/kg), applied together with carbamazepine, valproate or phenobarbital, significantly reduced their ED50 values against maximal electroshock - from 13.9 to 7.5 mg/kg, from 291 to 242 mg/kg, and from 18.6 to 11.1 mg/kg, respectively. At the dose of 50 mg/kg, it also potentiated the protective activity of carbamazepine. However, 5-fluoroindole-2-carboxylic acid, up to 100 mg/kg, did not affect the anti-convulsive activity of diphenylhydantoin. When applied at doses equal to their ED50 values against maximal electroshock-induced convulsions, carbamazepine (13.9 mg/kg), phenobarbital (18.6 mg/kg) and valproate (291 mg/kg) did not affect the motor performance of mice in the chimney test. 5-Fluoroindole-2-carboxylic acid (100 mg/kg produced a significant motor impairment, at 50 mg/kg it did not affect the motor performance. The combined treatment of 5-fluoroindole-2-carboxylic acid (100 mg/kg) with carbamazepine, phenobarbital or valproate, providing a 50% protection against maximal electroshock, resulted in motor impairment. Only the combination of 5-fluoroindole-2-carboxylic acid (50 mg/kg) with carbamazepine (8.6 mg/kg) did not significantly influence this parameter. Almost all of the antiepileptic drugs studied, when administered at doses equal to their ED50 values against maximal electroshock, did not influence retention in the passive avoidance task, which is a measure of long-term memory. Only valproate (291 mg/kg) worsened long-term memory. The combined treatment of 5-fluoroindole-2-carboxylic acid (100 mg/kg) with carbamazepine or phenobarbital, providing a 50% protection against maximal electroshock, did not affect the retention. The combination of 5-fluoroindole-2-carboxylic acid (100 mg/kg) with valproate (242 mg/kg) caused a significant impairment of long-term memory and mortality of 50% of animals 24h following the administration. The results suggest that the blockade of the strychnine-insensitive glycine site may lead to an enhancement of the protective activity of some conventional antiepileptic drugs, which is associated with pronounced side-effects and lethality in some cases.     

Treatment of lead toxicity in calves

Thiamine hydrochloride alone or in combination with calcium edetate (Ca-EDTA) was used to treat experimentally-induced lead toxicity in calves. In 12 calves lead toxicity was induced by po administration of 5 mg lead acetate/kg/d until the development of overt signs. The calves were divided into 3 groups: untreated control; thiamine-treated; and thiamine+Ca-EDTA-treated. The use of 25 mg thiamine/kg sc twice daily cured 2/4 calves, whereas 4/4 calves recovered with 25 mg thiamine+110 mg Ca-EDTA/kg iv twice daily. Lead concentrations in blood and tissues were significantly lower and histopathologic lesions were less pronounced in the treated calves. Treatment with thiamine+Ca-EDTA was more effective than the use of thiamine alone.     

Blood lead of intravenous drug users

Ethanol, morphine, cocaine and amphetamine were examined in place conditioning. After determination of initial preferences, animals were conditioned with ethanol (1 g/kg), morphine (5 mg/kg), cocaine (5 mg/kg) and amphetamine (5 mg/kg) alone or with combinations of these drugs plus naloxone (1 mg/kg). Naloxone prevented the ability of all drugs used to produce a place preference. The reinforcing properties of ethanol and morphine were reduced by sodium nitroprusside at a dose equal to 1/10 of LD50 given before preference testing. Molsidomine (1/10 LD50 and 1/20 LD50) altered the expression of the conditioned place preference produced by ethanol but not by morphine. Results of the present study suggest the involvement of endogenous opioids and probably of nitric oxide in the rewarding actions of drugs of abuse.     

Absorption, disposition kinetics, and metabolic pathways of cyclohexene oxide in the male Fischer 344 rat and female B6C3F1 mouse

Cyclohexene oxide (CHO) is a monomer intermediate used in the synthesis of pesticides, pharmaceuticals, and perfumes. Although CHO has a variety of industrial uses where direct human exposure is possible, very little is known about its fate in the body. Therefore, the objectives of this study were to determine the absorption, distribution, metabolism, and excretion of cyclohexene oxide after oral, intravenous, and dermal exposure in male Fischer 344 rats and female B6C3F, mice. After intravenous administration of [14C]CHO (50 mg/kg), CHO was rapidly distributed, metabolized, and excreted into the urine. Plasma concentrations of CHO rapidly declined and were below the limit of detection within 60 min. Average (+/- SD) values for terminal disposition half-life, apparent volume of distribution at steady-state, and systemic body clearance were: 19.3 +/- 1.6 min; 0.44 +/- 0.08 liter/kg; and 31.3 +/- 0.5 ml/kg * min, respectively. After oral administration of [14C]CHO (10 and 100 mg/kg), it was found that 14C-equivalents were rapidly excreted in the urine of both species. At 48 hr, the majority of the dose (73-93%) was recovered in urine, whereas fecal elimination accounted for only 2-5% of the dose. At no time after oral administration was parent CHO detected in the blood. However, its primary metabolite cyclohexane-1,2-diol was present for different lengths of time depending on the dose. Four metabolites were detected and identified in mouse urine by MS: cyclohexane-1,2-diol; cyclohexane-1,2-diol-O-glucuronide; N-acetyl-S-(2-hydroxycyclohexyl)-L-cysteine; and cyclohexane-1,2-diol-O-sulfate. The sulfate conjugate was not present in rat urine. Topical application of [14C]CHO (60 mg/kg) provided poor absorption in both species. The majority of 14C-equivalents applied dermally were recovered from the charcoal skin trap (approximately 90% of the dose). Only 4% of the dose was absorbed, and the major route of elimination was via the urine. To evaluate the toxicity of CHO, animals were given daily doses of CHO orally and topically for 28 days. No statistically significant changes in final body weights or relative organ weights were noted in rats or mice treated orally with CHO up to 100 mg/kg or up to 60 mg/kg when given topically. Very few lesions were found at necropsy, and none were considered compound related. In conclusion, regardless of route, CHO is rapidly eliminated and excreted into the urine. Furthermore, after either oral or dermal administration, it is unlikely that CHO reaches the systemic circulation intact due to its rapid metabolism, and is therefore unable to cause toxicity in the whole animal under the test conditions used in this study.     

Synergistic antithrombotic effects of argatroban and ticlopidine in the rat venous thrombosis model

Argatroban, a synthetic thrombin inhibitor, and ticlopidine, an anti-platelet agent, are major antithrombotic agents. We investigated the antithrombotic effects of a combination of argatroban and ticlopidine in the rat venous thrombosis model. Argatroban or ticlopidine inhibited thrombus formation in a dose-dependent manner; 50% inhibition (ED50) is obtained with 1.0 mg/kg/h (infusion) argatroban or 30 mg/kg (p.o.) ticlopidine. The combination of argatroban and ticlopidine inhibited thrombus formation in a dose-dependent manner; ED50 is obtained with 0.25 mg/kg/h argatroban plus 10 mg/kg ticlopidine and 0.5 mg/kg/h argatroban plus 3 mg/kg ticlopidine, whereas 0.5 mg/kg/h argatroban alone or 10 mg/kg ticlopidine alone had negligible effect (<20% inhibition). Isobole analysis showed that the antithrombotic effects of the combination of argatroban and ticlopidine involved synergism with potentiation. In contrast, the combination of argatroban and ticlopidine did not prolong the bleeding time synergistically. These data showed that the combination therapy of argatroban and ticlopidine should be clinically beneficial, but the different administration route may restrict the clinical usage.     

Photodynamic therapy of the ciliary body with tin ethyl etiopurpurin and tin octaethyl benzochlorin in pigmented rabbits

BACKGROUND AND OBJECTIVES: The authors used a pigmented rabbit model to investigate two photosensitizers, tin ethyl etiopurpurin (SnET2) and tin octaethyl benzochlorin (BNZ 203), to determine their potential for creating ciliary body injuries during photodynamic therapy (PDT). MATERIALS AND METHODS: The biodistribution of SnET2 (n = 10) and BNZ 203 (n = 9) was studied by fluorescence microscopy using a low light detection system, based on charged-coupled device photography, with digital image processing at 1 and 24 hours after injection. PDT with SnET2 (n = 8; 664 +/- 7-nm light; 75 mW/cm2; 50 or 100 J/cm2; 1-mm spot size) and BNZ 203 (n = 6; 689 nm; 75 mW/cm2; 50 or 100 J/cm2; 1-mm spot size) was performed at 24 hours post-injection. The control subjects for SnET2 (n = 5) and BNZ 203 (n = 3) were given a maximal light dose (100 J/cm2). RESULTS: Both photosensitizers demonstrated an intravascular distribution at 1 hour that shifted to a ciliary body distribution at 24 hours (SnET2 much greater than BNZ 203). In addition, the SnET2 demonstrated suborgan localization to the nonpigmented ciliary body epithelium. Both photosensitizing agents were able to produce selective injury to the rabbit ciliary body (SnET2 much greater than BNZ 203), with evidence of a small component of thermal damage (SnET2 greater than BNZ 203). CONCLUSIONS: PDT with SnET2 or BNZ 203 can produce selective injury to the pigmented rabbit ciliary body. The nonpigmented ciliary body epithelium exhibits selective retention of SnET2. This finding warrants further investigation.     

High prevalence of hepatitis C virus infection in patients with non-Hodgkin''s lymphoma at the onset. Preliminary results of an Italian multicenter study]

Inhibitors of carbonic anhydrase activity have been found to increase blood and organ PCO2 and to increase blood flow (BF) in individual organs. To determine whether carbonic anhydrase inhibition coordinately induces an increase in BF in several organs, we assayed the effect of the carbonic anhydrase inhibitor, acetazolamide (AZ), on BF in rabbit organs using the colored microsphere (CM) assay. Eight female white rabbits were anesthetized with ketamine and urethane, and administered three sequential doses of 4 mg/kg AZ. After each dose, the rabbits were injected with 9 x 10(5) CMs of different colors, and arterial blood was collected. We found that AZ had no effect on blood pressure, body temperature, hemoglobin concentration, or PaCO2. In contrast, 12 mg/kg AZ significantly increased PaO2 and significantly decreased base excess. When we measured organ BF, we observed, in response to 12 mg/kg AZ, an 82% increase in brain BF and a 55% increase in kidney BF, but no change in BF of the liver, stomach wall, or abdominal muscle. These findings suggest that the inhibition of carbonic anhydrase activity by AZ, which decreases the rate of CO2 conversion to HCO3-, causes the retention of CO2 in tissues and organs, and thus increases BF in specific organs. Administration of carbonic anhydrase inhibitors, such as AZ, may increase BF to the brain and kidney without reducing PaO2, thereby increasing the supply of oxygen in conditions involving hypoxia such as ischemia and shock.     

Evaluation of the echinocandin antifungal MK-0991 (L-743,872): efficacies in mouse models of disseminated aspergillosis, candidiasis, and cryptococcosis

The in vivo activity of the Merck antifungal echinocandin drug candidate MK-0991 (L-743,872) was evaluated in mouse models of disseminated candidiasis, aspergillosis, and cryptococcosis. The echinocandins are potent inhibitors of 1,3-beta-D-glucan synthase. Two models of disseminated candidiasis were used. In a Candida albicans mouse survival model with both DBA/2N and CD-1 mice, estimates of the 50% effective doses (ED50s) of MK-0991 were 0.04 and 0.10 mg/kg of body weight/dose at 21 days after challenge, respectively. In a C. albicans target organ assay (TOA) with DBA/2N mice, MK-0991 at levels of > or =0.09 mg/kg/dose significantly reduced the numbers of C. albicans CFU/g of kidneys compared to the numbers in the kidneys of control mice from 1 to 28 days after challenge. Even when given as a single intraperitoneal dose either 30 min or 24 h after challenge, MK-0991 was effective and significantly reduced the numbers of C. albicans CFU/g of kidney compared to those in the controls. MK-0991 was >300-fold less active when it was administered orally than when it was administered parenterally. MK-0991 was efficacious in mouse TOAs against other C. albicans strains and Candida species including Candida tropicalis, Candida (Torulopsis) glabrata, Candida lusitaniae, Candida parapsilosis, and Candida krusei. MK-0991 was ineffective against disseminated Cryptococcus neoformans infections. In the model of disseminated aspergillosis in mice, MK-0991 at doses of > or =0.02 mg/kg/dose significantly prolonged the survival of DBA/2N mice, with estimates of the ED50 and ED90 of MK-0991 being 0.03 and 0.12 mg/kg/dose, respectively, at 28 days after challenge. MK-0991 is a potent, parenterally administered therapeutic agent against disseminated candidiasis and aspergillosis that warrants further investigation in human clinical trials.     

The renal effects of the water-soluble, non-folylpolyglutamate synthetase-dependent thymidylate synthase inhibitor ZD9331 in mice

ZD9331 is a novel, potent thymidylate synthase (TS) inhibitor which does not require polyglutamation by folylpolyglutamate synthetase (FPGS) for its activity. In contrast to Tomudex (ZD1694), ZD9331 may therefore be active against tumours with low FPGS activity. ZD9331 shows anti-tumour activity by both 24-h infusion and bolus administration in the murine thymidine kinase-deficient (TK -/-) lymphoma L5178Y. In view of the history of renal toxicity with some earlier TS inhibitors and the possible therapeutic use of bolus ZD9331, we have examined the effects of bolus ZD9331 dose and route of administration on plasma and kidney pharmacokinetics and renal function in mice. Renal function was assessed by measuring [14C]inulin clearance, and drug concentrations were assayed by reverse-phase high-performance liquid chromatography (HPLC). Renal function was unaffected by ZD9331 up to 150 mg kg(-1) either i.v. or i.p. However, at 200 mg kg(-1), glomerular filtration rate was significantly inhibited following i.v. but not i.p. administration. Pharmacokinetic studies showed that these effects were consistent with the markedly higher plasma drug concentrations occurring during early times following i.v. dosing, although the plasma drug profiles were otherwise similar for both routes. Kidney drug concentrations were slightly elevated in i.v.- versus i.p.-treated animals at the low dose (50 mg kg(-1)), with a correspondingly larger area under the curve. However, at the highest dose (200 mg kg(-1)), peak kidney drug concentrations were 20-fold higher following i.v. administration than after i.p., with marked kidney retention, resulting in a 50-fold greater kidney drug exposure for the i.v. versus the i.p. route. These data show that ZD9331 is non-nephrotoxic at active anti-tumour doses (50 mg kg(-1) i.p.) in mice, and only at very high bolus i.v. doses is there impaired renal function as a result of very high peak plasma concentrations. These adverse effects can be readily overcome by i.p. administration, indicating the likely need for short infusions in clinical settings.     

Localization of Six4/AREC3 in the developing mouse retina; implications in mammalian retinal development

BACKGROUND: We designed an antisense phosphorothioate oligodeoxynucleotide (oligo) to specifically inhibit the expression of rat intercellular adhesion molecule-1 (ICAM-1) mRNA (IP-9125). METHODS: IP-9125 oligo was delivered intravenously by osmotic pump alone or in combination with cyclosporine (CsA) to recipients in order to prevent the rejection of kidney or heart allografts. In additional experiments, kidney allografts were perfused with IP-9125 before grafting. RESULTS: IP-9125 inhibited ICAM-1 mRNA and ICAM-1 protein expression in rat aortic endothelial cells; scrambled controls IP-12140 and IP-13944 were ineffective. Untreated ACI (RT1a) recipients rejected Lewis (RT1l) kidney allografts at a mean survival time of 8.5+/-1.1 days. A 14-day intravenous administration of 2.5 mg/kg/day IP-9125 prolonged the survival of kidney allografts to 39.2+/-16.4 days; 5.0 mg/kg/day, to 43.0+/-17.5 days; and 10.0 mg/kg/day, to 50.4+/-21.6 days. In contrast, a scrambled control IP-12140 was not effective. A combination of 10 mg/kg/day IP-9125 and 1.0 mg/kg/day CsA delivered for 14 days synergistically extended kidney allograft survival times 88.5+/-7.5 days. In contrast, the combination of 10.0 mg/kg/day control IP-12140 with CsA was ineffective (20.7+/-3.2 days) when compared with CsA alone (20.2+/-4.0 days). Similar results were obtained for heart transplants in recipients treated with IP-9125 alone or in combination with CsA. Furthermore, in situ immunostaining showed that IP-9125 significantly reduced the expression of ICAM-1 protein in kidney allografts. Finally, perfusion of kidney grafts alone with 20.0 mg per 2 ml of IP-9125 protected kidney allografts from rejection (37.5+/-7.5 days; P < 0.001), whereas perfusion with 20 mg per 2 ml of control IP-12140 was ineffective (12.6+/-5.0 days). CONCLUSIONS: Rat ICAM-1 IP-9125 oligo inhibits ICAM-1 protein expression in vitro and in vivo as well as blocks allograft rejection when used for pretreatment of donors, graft perfusion, or postoperative treatment of recipients.     

Biokinetics of lead in various organs of rats using radiotracer technique

Uptake, distribution, and elimination of lead in various organs of rats have been studied using a radiotracer technique. The elimination data for various organs, except whole blood, is fitted to a double-exponential function using a computer program. The biological half-lives along with the percent elimination of lead by two different decay modes in testis, epididymis, prostate, and seminal vesicles are being reported together with that in liver, kidney, blood, and whole body. It is evident from this study that the elimination of lead is limited for all the organs and permits lead accumulation in the bone, where it is stored and becomes almost unavailable for elimination. Lead levels in blood, testis, and femur of lead acetate-fed rats measured using atomic absorption spectroscopy have been correlated to the uptake of 210Pb in various organs.     

Mobilization of lead by calcium versenate and dimercaptosuccinate in the rat

1. Calcium disodium ethylenediaminetetraacetate (CaNa2 EDTA) and meso-2,3-dimercaptosuccinic acid (DMSA) individually and in permutation-combination in various doses (0.1, 0.2 and 0.4 mmol/kg bodyweight) were investigated for their efficacy to mobilize lead from vital tissues into urine and faeces and to restore the lead-sensitive biochemical parameters in lead pre-exposed rats with a view to develop the most acceptable treatment regimen for lead poisoning with a minimal loss of endogenous essential elements. 2. The combined therapy was more effective than a single chelator treatment. 3. The combination of 0.2 mmol/kg CaNa2EDTA + 0.4 mmol/kg DMSA caused a lower depletion of zinc, calcium and iron but possessed almost equal capability to that of 0.4 mmol/kg CaNa2EDTA + 0.4 mmol/kg DMSA to produce urinary as well as faecal excretion of lead, to reduce the tissue burden of lead, including that of the brain, and to reverse lead-induced biochemical alterations. 4. The combination of 0.2 mmol/kg CaNa2EDTA + 0.4 mmol/kg DMSA has shown a definite improvement over previously reported combinations in terms of removal of lead from tissues, particularly the brain, restoration of urinary delta-aminolevulinic acid levels and a decrease in the loss of body zinc and is, therefore, recommended for the treatment of lead intoxication.     

Lead in tissues of deceased lead smelter workers

Smelter workers are exposed to a number of metals and other substances in dust, fumes and gases. The concentrations of lead in liver, lung, kidney, brain, hair and nails were determined in 32 deceased, long-term exposed male lead smelter workers, and compared with those of 10 male controls. The lead levels in liver, lung, kidney and brain were analyzed by atomic absorption spectrophotometry. X-ray fluorescence was used for the determinations in hair and nails. Lead in blood had been determined repeatedly in the lead workers since 1950, which made it possible to calculate a time-integrated blood lead index for each worker. The highest lead levels in soft tissues were found in liver, followed in order of concentration by kidney, lung and brain, among both exposed workers and controls. These organ lead concentrations were all significantly higher among the workers as compared with the control group (p < or = 0.02). The largest difference between workers and controls was found in brain tissue (ratio between median values = 5.6). The lead levels in hair and nails were of the same magnitude in the two groups. The workers showed positive correlations between lead concentrations in liver and kidney (Spearman's rho = rs = 0.59; p < 0.001), liver and hair (rs = 0.51; p = 0.003), liver and nails (rs = 0.52; p = 0.002) and hair and nails (rs = 0.52; p = 0.002). Lead concentrations in kidney correlated well with lead levels in hair (rs = 0.57; p = 0.001) and nails (rs = 0.51; p = 0.003), respectively. The positive correlation between the lead concentrations in liver and kidney indicates that these organs belong to the same soft tissue lead pool in the body. In retired lead workers, positive correlations were observed between the lead concentrations in liver and the cumulative blood lead index (CBLI) (rs = 0.50; p = 0.016), as well as between lead levels in kidney and CBLI (rs = 0.51; p = 0.014).     

Effect of papain-induced emphysema on the distrubtion of pleural surface pressure

In vivo experiments using 203Pb and radioactively labelled precursors such as [14C] arginine and [3H] tryptophan were performed to identify lead binding components in rat liver. The distribution of lead in 9 tissues and the intracellular distribution in liver and kidney was also investigated. Male rats were injected intravenously with 18 mug of 203Pb/rat and the 203Pb radioactivity was measured in whole tissues as well as in nuclei, mitochondria, lysosomes, microsomes and soluble fractions obtained by centrifugation of liver and kidney homogenates. The subcellular fractions from liver were purified and fractionated into macromolecular components by ultracentrifugation, gel filtration, ion exchange chromatography and solvent extraction. Nuclei were fractionated into membranes, chromatin proteins (histone and residual non-histone proteins) and DNA. Most of the lead was detected in the nuclear membrane fraction bound exclusively to membrane proteins and absent in phospholipids. The intranuclear lead was associated with histone fractions and other basic or very weakly acid proteins as indicated by the incorporation of [14C] arginine and [3H] tryptophan. Lead was present in the chromatographically purified DNA fraction but whether lead was really bound to the nucleic acid was not determined. Mitochondria were fractionated into heavy, soluble and light subfractions representing the inner membranes, the intramitochondrial matrix and the outer membranes respectively. These subfractions contained appreciable quantities of lead. No appreciable lead was present in lipids of the mitochondrial membranes. Significant quantities of lead were associated with the endoplasmic reticulum. Fractionation of microsomes into rough and smooth membranes showed that lead was almost exclusively bound to membranes of rough-surfaced microsomes associated with the heavy rough membrane subfraction. No significant lead was present in the free polysome subfraction or in lipids from the endoplasmic reticulum. More than one lead binding site was identified in the soluble fraction, the high molecular weight components representing the most important lead binding site.     

Beneficial effects of the combination of idebenone and manidipine 2HCl on neurological deficits and histological changes following cerebrovascular lesions in stroke-prone spontaneously hypertensive rats

We investigated the effects of the combination of idebenone, an energy metabolism enhancer, and manidipine 2HCl, a dihydropyridine-derivative calcium antagonist, on neurological deficits and histological changes in the brain and kidneys of stroke-prone spontaneously hypertensive rats (SHRSP) with cerebrovascular lesions (stroke). The SHRSP were kept on a 1% NaCl solution as their drinking water to synchronize the onset of stroke. After the onset of stroke symptoms, the salt solution was replaced with tap water. On the day following the onset of stroke, idebenone (50 mg/kg), manidipine 2HCl (2 mg/kg) or a combination of idebenone (50 mg/kg) and manidipine 2HCl (2 mg/kg) was administered orally once a day for 3 weeks. In the combination group and manidipine 2HCl-treated group, the neurological deficits after the onset of stroke were ameliorated during the entire experimentalperiod. Especially, the combination significantly decreased the number of days with severe neurological deficits as compared to the control group. The combination and manidipine 2HCl significantly recovered the decrease in body weight and ameliorated the increase of brain weight, which was mainly caused by edema, significantly as compared to the control group. Manidipine 2HCl ameliorated the histological changes in the brain. In the combination group, the histological changes in both the brain and the kidneys were ameliorated. In conclusion, the combination of idebenone and manidipine 2HCl significantly ameliorated the neurological deficits and the histological changes in the brain and the kidney of SHRSP with stroke as compared to each individual treatment. We concluded that manidipine 2HCl enhances the therapeutic effect of idebenone in the treatment of cerebrovascular diseases.     

Effects of methyltestosterone on insulin secretion and sensitivity in women

The frequent coexistence of hyperandrogenism and insulin resistance is well established; however, whether a cause and effect relationship exists remains to be established. In this study we tested the hypothesis that short-term androgen administered to women would induce insulin resistance. To test this hypothesis, regularly menstruating, nonobese women were studied before and during methyltestosterone administration (5 mg tid for 10-12 days) by the hyperglycemic (n=8) and euglycemic, hyperinsulinemic (n=7) clamp techniques. Short-term methyltestosterone administration had no significant effects on the fasting levels of glucose, insulin, c-peptide, glucagon, or glucose turnover. During the hyperglycemic clamp studies, the mean glucose level during the final hour was 203+/-2 and 201+/-1 mg/dL in the methyltestosterone and control studies, respectively. The insulin response to this hyperglycemic challenge was slightly but not significantly greater during methyltestosterone treatment (first phase 59+/-8 vs. 50+/-8 microU/mL in controls; second phase 74+/-9 vs. 67+/-9 microU/mL in controls; total insulin response 133+/-16 vs. 117+/-15 microU/mL in controls). In spite of this, glucose uptake was reduced from the control study value of 10.96+/-1.11 to 7.3+/-0.70 mg/kg/min by methyltestosterone (P < 0.05). The ratio of glucose uptake per unit of insulin was also significantly reduced from a control study value of 14.3+/-1.4 to 9.4+/-1.3 mg/kg/min per microU/mL x 100 during methyltestosterone administration. In the euglycemic hyperinsulinemic clamp studies, insulin was infused at rates of 0.25 and 1.0 mU/kg/min to achieve insulin levels of approximately 25 and 68 microU/mL, respectively. During low-dose insulin infusion, rates of endogenous hepatic glucose production were equivalently suppressed from basal values of 2.37+/-0.29 and 2.40+/-0.27 mg/kg/min to 0.88+/-0.25 and 0.77+/-0.26 mg/kg/min in the methyltestesterone and control studies respectively. Whole body glucose uptake during low-dose insulin infusion was minimally affected. During the high-dose insulin infusion, endogenous hepatic glucose production was nearly totally suppressed in both groups. However, whole body glucose uptake was reduced from the control value of 6.11+/-0.49 mg/kg/min to 4.93+/-0.44 mg/kg/min during methyltestosterone administration (P < 0.05). Our data demonstrate that androgen excess leads to the development of insulin resistance during both hyperglycemic and euglycemic hyperinsulinemia. These findings provide direct evidence for a relationship between hyperandrogenemia and insulin resistance, and its associated risk factors for cardiovascular disease.     

Hepato-splanchnic blood flow and oxygen extraction capabilities during experimental tamponade: effects of endotoxin

We studied the hepato-splanchnic vascular response and changes in O2 extraction capabilities to a reduction in blood flow following endotoxemia. Fourteen anesthetized and mechanically ventilated dogs were divided into two groups of seven each. Group 1 received 2 mg/kg of E. coli endotoxin, and group 2 served as a control. After initial fluid resuscitation following endotoxic shock, regional blood flow estimated by an ultrasonic technique increased similarly in the hepatic artery, portal vein, and mesenteric artery, but microvascular blood flow estimated by a laser Doppler technique was lower in the liver than in the intestinal mucosa. When blood flow was reduced by cardiac tamponade, endotoxin-treated animals had greater whole body and regional critical O2 delivery (DO2crit) and lower whole body, liver, and intestinal critical O2 extraction ratios (O2ERcrit). DO2crit was higher in the liver than in intestine but O2ERcrit was similar in the two organs. Whole body DO2crit at the onset of organ O2 supply dependency was similar under control (9.4 +/- 1.9 mL/kg. min for whole body, 10.3 +/- 4.7 mL/kg. min for liver, and 10.0 +/- 2.6 mL/kg. min for intestine) and endotoxic conditions (13.6 +/- 3.2 mL/kg. min for whole body, 15.6 +/- 2.7 mL/kg. min for liver, and 15.4 +/- 8.7 mL/kg. min for intestine). We conclude that fluid-resuscitated endotoxic shock in dogs is characterized by blood flow redistribution within the liver and intestine. Microvascular depression may be more severe in the liver than in the intestinal mucosa, although the whole body, the liver, and the intestine became O2 supply-dependent simultaneously.     

Effects of chloroquine treatment on antioxidant enzymes in rat liver and kidney

The effect of chloroquine (CHQ) administration on antioxidant enzymes in rat liver and kidney was studied. Male Sprague-Dawley rats were administered 20 mg/kg CHQ once a week for 4 weeks (chronic treatment) or a single dose at 10 or 20 mg/kg (acute treatment). Antioxidant enzyme activities were determined in cytosolic fractions of liver and kidney, whereas reduced glutathione (GSH) and malondialdehyde (MDA) were determined in tissue samples. Results indicate minimal effects of acute CHQ treatment, whereas chronic treatment with CHQ differentially affected antioxidant enzymes in the two organs. Superoxide dismutase activity was increased nearly twofold, while activities of selenium glutathione peroxidase (GPX), catalase, and NAD (P) H: quinone oxidoreductase were decreased in livers of CHQ-treated rats compared to controls. No significant effects of CHQ on glutathione reductase, GSH, and MDA levels were seen in the liver. Fewer effects of CHQ were observed in the kidney where a decrease in GPX activity and an increase in MDA levels was seen. Lowering of antioxidant enzymes activities in the liver by CHQ could render the organ more susceptible to subsequent oxidative stress; while increased MDA production after CHQ treatment in the kidney indicate that the organ is being subjected to oxidative stress. This could have implications for prolonged chloroquine intake.