Effect of temperature on serum protein binding characteristics of phenytoin in monotherapy paediatric patients with epilepsy.

OBJECTIVES: To determine the effects of temperature on binding characteristics of phenytoin to serum proteins in paediatric patients with epilepsy. METHOD: Serum samples examined in the study were obtained from 41 paediatric patients (23 male, 18 female) with epilepsy on phenytoin monotherapy. Their age ranged from 1 to 15 years (mean +/- SD, 10;2 +/- 4;0 years). Protein binding of phenytoin was evaluated by ultrafiltration under current laboratory routine conditions (25 +/- 3 degrees C) or at a temperature of 37 degrees C. The in vivo binding parameters of phenytoin to serum proteins were determined using a binding equation derived from the Scatchard equation for a one-site binding model. RESULTS: Significant differences were observed in serum concentrations of unbound phenytoin at the two temperatures (P < 0;05). The mean association constant L/micromol (K) of phenytoin to serum proteins is 0.016 L/micromol at 25 +/- 3 degrees C and 0;009 L/micromol at 37 degrees C, while mean total concentration of binding sites (n(Pt)) seems to be similar between the two temperatures (682 micromol/L for 25 +/- 3 degrees C and 746 micromol/L for 37 degrees C). Significant differences were observed in binding characteristics of phenytoin to serum proteins for the different temperature conditions of ultrafiltration (P < 0;05). CONCLUSION: Our study confirms that binding affinity for phenytoin-serum protein interaction is approximately 44% lower at 37 degrees C than at 25 +/- 3 degrees C and consequently, binding potential (K.n(Pt)) is approximately 38% lower at 37 degrees C than at 25 +/- 3 degrees C.

In vivo binding characteristics of phenytoin to serum proteins in monotherapy pediatric patients with epilepsy.

AIM: The aim of the present study was to determine the binding characteristics of phenytoin (PHT) to serum proteins in the pediatric population. Binding parameters of PHT to serum proteins in our study were conducted to compare with in vivo or in vitro binding parameters of PHT to serum proteins in adult subjects reported by other investigators. SUBJECTS AND MATERIALS: Serum samples in the study were obtained from 40 pediatric patients (16 male, 24 female) receiving PHT monotherapy. Their age ranged from 1 to 15 years (9.2 +/- 3.6 years, mean +/- SD). The in vivo population binding parameters of PHT to serum proteins and theoretical minimal unbound serum PHT fraction (fu) were determined using an equation derived from the Scatchard equation. RESULTS: The association constant (Ka) was 0.014 l/micromol, while the total concentration of binding sites (n(Pt)) was 747 micromol/l. The number of binding sites per albumin molecule (n) was 1.13, while binding ability (n x Ka) was 0.0161/micromol. The fu was 0.087. The n x Ka is approximately 1.2 times higher in PHT monotherapy adult patients of Pospisil et al. [1992] (i.e. 0.0191 l/micromol) than in all our patients. The association constant is approximately 1.3 times higher in the in vitro study of Monks et al. [1978] (i.e. 0.0186 l/micromol) than in our study, while n is similar between the two studies. The fu in our pediatric patients is similar to the unbound serum PHT fraction in adult patients receiving PHT therapy reported by Richens [1979] (i.e. 0.1). CONCLUSION: Our results suggest that there may be small differences in the binding characteristics of PHT to serum proteins between Japanese pediatric and non-Japanese adult subjects. The unbound serum fraction of PHT in pediatric patients with epilepsy can be assumed to be relatively constant in the therapeutic concentration range of PHT.

Effect of temperature on binding characteristics of phenytoin to serum proteins in monotherapy adult patients with epilepsy.

The effects of temperature on binding characteristics of phenytoin (PHT) to serum proteins were determined in adult patients with epilepsy. Serum samples examined in the study were obtained from 47 adult patients (29 men, 18 women) with epilepsy on PHT monotherapy. Ages ranged from 18 to 64 years (mean [SD], 36.8 [12.1] years). Protein binding of PHT was evaluated by ultrafiltration under current laboratory routine conditions (25 +/- 3 degrees C) or at a temperature of 37 degrees C. The in vivo binding parameters of PHT to serum proteins were determined using a binding equation derived from the Scatchard equation for a one-site binding model. Significant differences were observed in serum concentrations of unbound PHT between paired data (P <.05). The mean association constants (K) of PHT to serum proteins are 0.009 L micromol(-1) at 25 +/- 3 degrees C and 0.003 L micromol(-1) at 37 degrees C, whereas mean total concentrations of binding sites [n(Pt)] are 1215 micromol L(-1) for 25 +/- 3 degrees C and 2263 micromol L(-1) for 37 degrees C. Significant differences were observed in binding characteristics of PHT to serum proteins between the data determined in different conditions of ultrafiltration (P <.05). Our study confirms that binding affinity for PHT-serum protein interaction is approximately 67% lower at 37 degrees C than at 25 +/- 3 degrees C, and, consequently, binding potential [K.n(Pt)] is approximately 38% lower at 37 degrees C than at 25 +/- 3 degrees C.

In vivo binding characteristics of phenytoin to serum proteins in monotherapy for adults with epilepsy.

The aim of the present study was to determine the binding characteristics of phenytoin (PHT) to serum proteins in the adults. Binding parameters of PHT to serum proteins in our study were compared with in vivo or in vitro binding parameters of PHT to serum proteins reported by other investigators. Serum samples in the study were obtained from 36 adult patients (17 men, 19 women) receiving PHT monotherapy. A total of 43 steady-state concentrations were analyzed in the study. Patients' age ranged from 16 to 73 years (mean [SD], 42.9 [14.7] years). The in vivo population binding parameters of PHT to serum proteins and theoretical minimal unbound serum PHT fraction (fu) were determined using an equation derived from the Scatchard equation. The association constant (K) was 0.014 L x micromol(-1), whereas the total concentration of binding sites (n(Pt)) was 754 micromol x L(-1). The number of binding sites per albumin molecule (n) was 1.16, whereas binding ability (n.K) was 0.016 L x micromol(-1). The fu was 0.087. The n.K is approximately 1.2 times higher in PHT monotherapy patients of Pospísil and Perlík (ie, 0.0191 L x micromol(-1)) than in all our patients. The association constant is approximately 1.3 times higher in the in vitro study of Monks et al (ie, 0.0186 L x micromol(-1)) than in our study, whereas n is similar between the two studies. The fu in our patients is similar to the unbound serum PHT fraction in patients receiving PHT therapy reported by Richens (ie, 0.1). Our results suggest that there may be small differences in the binding affinity of PHT to serum proteins between in vivo and in vitro studies. The unbound serum fraction of PHT in epileptic patients can be assumed to be relatively constant in the therapeutic concentration range of PHT.

No gender effect on binding characteristics of phenytoin to serum proteins in monotherapy for adult patients with epilepsy.

The aim of the present study was to determine the gender-related binding characteristics of phenytoin (PHT) to serum proteins in adult patients with epilepsy. Serum samples examined in the study were obtained from 80 adult patients (40 men and 40 women) with epilepsy on PHT monotherapy. Their age ranged from 16 to 64 years (mean [SD], 36.0 [11.7] years). Protein binding of PHT was evaluated by ultrafiltration under current laboratory routine conditions (25 +/- 3 degrees C). The in vivo binding parameters of PHT to serum proteins were determined using a binding equation derived from the Scatchard equation for a one-site binding model. No significant differences were observed in age and serum concentrations of albumin between male and female patients (p > 0.05), but significant differences were observed in serum concentrations of total and unbound PHT between the two groups (p < 0.05). The mean association constant of PHT to serum proteins is the same value of 0.008 L micromol(-1) between male and female patients, whereas total concentration of binding sites seems to be similar between the two groups (1389 micromol L(-1) for men and 1345 micromol L(-1) for women). No significant differences were observed in binding characteristics of PHT to serum proteins between male and female patients (p > 0.05). Our results show that gender does not have a significant effect on the binding characteristics of PHT to serum proteins in adult patients receiving monotherapy under normal pathophysiologic conditions.

Protection against cis-diamminedichloroplatinum-induced nephrotoxicity by 2,3-dimercaptosuccinic acid in rats.

The present study was designed to examine the usefulness of 2,3-dimercaptosuccinic acid (DMSA) for the purpose of reducing cis-diamminedichloroplatinum (DDP)-induced nephrotoxicity and effective clinical use of DDP and safe. The effectiveness of DMSA on the DDP-excretion in rat kidney was observed by measuring the platinum concentration using Atomic Absorption Instrument. Co-administration of DMSA (1.0 or 2.0 mmol/kg) 1 hour after DDP injection (20 mumol/kg) showed more decrease in the platinum concentration than that immediately after DDP injection. The alleviating effect of DMSA on DDP toxicity was evaluated by lipid peroxidation, enzymatic antioxidants, and glutathione levels. The administration of DDP alone caused a significant increase in lipid peroxidation and significant decreases in enzymatic antioxidants and glutathione levels in the kidney. Co-administration of DMSA (2.0 mmol/kg) 1 hour after DDP injection showed the most effective reduction of these enzymatic damages caused by DDP. These findings suggested that the co-administration of DMSA (2.0 mmol/kg) 1 hour after DDP injection leads DDP to effective excrete from renal tissue and suppresses the lipid peroxide reaction and results in reduction of nephrotoxicity.

Temperature effect on serum protein binding kinetics of phenytoin in monotherapy patients with epilepsy.

The effects of temperature on the binding kinetics of phenytoin (PHT) to serum proteins were determined in patients with epilepsy. Serum samples examined in the study were obtained from 59 patients (31 male, 28 female) with epilepsy on PHT monotherapy. Their age ranged from 3 to 64 years (mean (SD), 23.3 (16.3) years). Protein binding of PHT was evaluated by ultrafiltration under current routine laboratory conditions (25 +/- 3 degrees C) or at a temperature of 37 degrees C. The in vivo binding parameters of PHT to serum proteins were determined using a binding equation derived from the Scatchard equation for a one-site binding model. Significant differences were observed in serum concentrations of unbound PHT between paired data (P < 0.05). The mean association constant (K) of PHT to serum proteins is 0.011 microM-1 at 25 +/- 3 degrees C and 0.006 microM-1 at 37 degrees C, while mean total concentration of binding sites (n(Pt)) is 1002 microM for 25 +/- 3 degrees C and 1112 microM for 37 degrees C. Significant differences were observed in the binding kinetics of PHT to serum proteins for the different temperature conditions of ultrafiltration (P < 0.05). Our study confirms that binding affinity for PHT-serum protein interaction is approximately 45% lower at 37 degrees C than at 25 +/- 3 degrees C and consequently, binding potential (K.n(Pt)) is approximately 39% lower at 37 degrees C than at 25 +/- 3 degrees C.

Effects of eosinophil granule major basic protein on phosphatidylcholine secretion in rat type II pneumocytes.

Eosinophils are involved in inflammatory diseases such as asthma. We previously reported that activated eosinophils increased the phosphatidylcholine (PC) secretion in primary cultures of rat type II pneumocytes. Increased PC secretion was confirmed to be partly mediated by superoxide anions released from activated eosinophils. However, the influence of eosinophil granule proteins on PC secretion is unknown at present. In this study, we determined whether eosinophil major basic protein (MBP) influences PC secretion. MBP dose dependently increased the PC secretion in rat type II pneumocytes without producing any cell damage. The MBP-induced increase in PC secretion was significantly reduced by preadministration of either H-7, a protein kinase inhibitor, or 1, 2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-AM, a chelator of intracellular Ca2+, but not by H-89, a protein kinase inhibitor. Our results suggest that the MBP-induced increase in PC secretion may provide mechanical stability and protect against lung atelectasis.

Effects of fatty acids on serum binding between furosemide and valproic acid.

The effects of fatty acids, including oleate, on the interaction between furosemide and valproic acid in sera at respective serum therapeutic concentration levels were investigated using an ultrafiltration technique. The free fraction of furosemide was significantly increased in the presence of valproic acid. Mutual displacement experiments indicated that furosemide and valproic acid share a common high affinity binding site on human serum albumin (HSA). The serum free fraction of furosemide was increased by the presence of six or more fatty acid molecules per HSA molecule. This fatty acid-induced increase in the unbound fraction of furosemide was further increased by the binding of valproic acid. However, the inhibition of furosemide binding to serum for a fatty acid-valproic acid-furosemide system is nearly the same as the additive effect of fatty acid and valproic acid on the furosemide to serum. Thus, the mechanism for the displacement of HSA-bound furosemide by valproic acid was concluded to be different from that for fatty acid-catalyzed displacement.

Serum protein binding kinetics of phenytoin in monotherapy patients.

OBJECTIVES: To determine the binding characteristics of phenytoin to serum proteins in the Japanese population and to compare these with those reported by other investigators. METHOD: Serum samples examined in the study were obtained from 72 patients (35 males, 37 females) receiving phenytoin monotherapy. The patients' ages ranged from 1 to 73 years (1-15 years, 36 subjects; 16-44 years, 20 subjects; 45-64 years, 13 subjects; > or = 65 years, 3 subjects). RESULTS: The in vivo population binding parameters of phenytoin to serum proteins and theoretical minimal unbound serum phenytoin fraction (fu) were determined using the Scatchard equation. The association constant (K) was 0.020 1/micromol, while the total concentration of binding sites (n(Pt) was 556 micromol/l. The number of binding sites per albumin molecule (n) was 0.85, while binding ability (n.K) was 0.017 l/micromol. The fu was 0.083. The n.K is approximately 1.1 times higher in patients of Pospísil et al. (26) (i.e. 0.0191 l/micromol) than in all our patients. The association constant is approximately 1.1 times higher in our study than in the in vitro study of Monks et al. (23) (i.e. 0-0186 l/micromol), while n is similar between the two studies. The fu in our patients is similar to the unbound serum phenytoin fraction in adult patients receiving phenytoin therapy reported by Richens (2) (i.e. 0.1). CONCLUSION: Our results suggest that there may be small differences in the binding characteristics of phenytoin to serum proteins between Japanese and non-Japanese subjects. The unbound serum fraction of phenytoin in our patients with epilepsy can be assumed to be relatively constant in the therapeutic concentration range of phenytoin.

Effects of xanthine derivatives on phosphatidylcholine secretion in rat type II pneumocytes in the presence of activated eosinophils.

We have previously reported that activated eosinophils enhanced the phosphatidylcholine (PC) secretion in type II pneumocytes. In this study, we have determined whether xanthine derivatives affect the PC secretion increased by activated eosinophils. Theophylline enhanced the increased PC secretion at 10(-5) M. 8-Phenyltheophylline dose-dependently enhanced the PC secretion. The enhanced secretion by either theophylline at 10(-5) M or 8-phenyltheophylline was suppressed by superoxide dismutase in combination with catalase. Pentoxifylline did not enhance the PC secretion increased by activated eosinophils, although it increased the PC secretion by itself. The PC secretion increased by theophylline at 10(-3) M or pentoxifylline was not suppressed by superoxide dismutase in combination with catalase. The present results suggest that xanthine derivatives increased the PC secretion in the co-culture of type II pneumocytes and activated eosinophils possibly through the inhibition of phosphodiesterases or the antagonism of adenosine receptors of the eosinophils.

[Effect of biological membrane stabilizing drugs (coenzyme Q10, dextran sulfate and reduced glutathione) on adriamycin (doxorubicin)-induced toxicity and microsomal lipid peroxidation in mice].

The protective effects of the biological membrane stabilizing drugs, coenzyme Q10 (CoQ), dextran sulfate (DS) and reduced glutathione (GSH), on doxorubicin (adriamycin, ADM)-induced toxicity and microsomal lipid peroxidation were studied in mice. The mice administered ADM with combined treatment of CoQ, DS or GSH showed a significantly longer survival time than the ADM control group (which were injected with 15 mg/kg of ADM twice). The optimum protective doses of these drugs against ADM-induced toxicity were 10 mg/kg/day (p.o.) for CoQ, 100 mg/kg/day (s.c.) for DS and 100 mg/kg/day (i.p.) for GSH. The survival times of the mice (expressed as a percent of the treated group per control group) were 224.1% for CoQ, 220.7% for DS and 213.7% for GSH. The groups treated with these drugs showed a significant decrease in mouse liver and heart microsomal lipid peroxidation in comparison to that of the ADM control group. These results suggest that the heart microsomal lipid peroxidation levels may be one of the indications of ADM-induced cardiac toxicity. These drugs tested in the present study may stabilize the heart microsomal membrane lipid or may improve the myocardiac mitochondrial functions over those in ADM-treated mouse.

Protective effects of various drugs on adriamycin (doxorubicin)-induced toxicity and microsomal lipid peroxidation in mice and rats.

The protective effects of clinically used drugs on the toxicity and microsomal lipid peroxidation induced by doxorubicin (adriamycin, ADM), an anthracycline type antitumor agent, were studied in mice and rats. Regarding the effects of anthracyclines (aclarubicin, ACL; daunorubicin, DAU; ADM; epirubicin, EPI; pirarubicin, PIR) on rat liver microsomal lipid peroxidation, ACL had the smallest effect, and effectiveness increased in the order of PIR, ADM, DAU and EPI. The increasing effect of lipid peroxidation induced by these drugs was closely correlated with the decrease in the body weight of mice administered intraperitoneally at a dose of 20 mg/kg and in rats at LD50 of the drugs. The survival times of ADM-administered mice (which were injected 15 mg/kg of ADM twice) treated with the following drugs, expressed as a percent of that of the control group, were 236% for adenosine triphosphate, 224% for coenzyme Q10 (Co Q), 235% for dextran sulfate (DS), 123% for dipyridamole, 121% for flavin adenine dinucleotide, 213% for reduced glutathion, 155% for inositol nicotinate, 157% for nicardipin and 297% for nicomol. The rat heart microsomal lipid peroxidation levels in vivo may be one of the indications of ADM-induced toxicity. The levels treated with DS correlated well with the development of ADM-induced toxicity: mouse survival time, change of body weight and tissue wet weight loss. Another type of drug, such as Co Q, may improve the myocardiac mitochondrial functions compared to those of ADM-administered mice.

[Effects of anthracycline drugs (aclarubicin, daunorubicin, doxorubicin, epirubicin, pirarubicin) on mouse acute toxicity and rat liver microsomal lipid peroxidation].

Effects of anthracycline type antitumor agents (aclarubicin, ACL; daunorubicin, DAU; doxorubicin, DOX; epirubicin, EPI; pirarubicin, PIR) on the acute toxicity to mouse, rat liver microsomal lipid peroxidation and mitochondrial functions in vitro were studied. ACL showed the least production of liver microsomal lipid peroxidation in all tested anthracyclines in the increasing order of PIR, DOX, DAU and EPI. The increase of production of lipid peroxidation induced by these drugs correlated well with the decrease in body weight of mice administered i.p. at 20 mg/kg and 50% lethal dose of these drugs. On the effect of mitochondrial function, all drugs tested decreased the oxygen uptake of state 3 and the level of respiratory control index. ACL showed the most severe inhibition of these functions in all drugs. These observations suggest that the degree of microsomal lipid peroxidation induced with the anthracycline drugs was related to the development of the drug acute toxicity.

Tissue concentration of doxorubicin (adriamycin) in mouse pretreated with alpha-tocopherol or coenzyme Q10.

The tissue concentration of doxorubicin (adriamycin; ADM) and its major metabolite (aglycone I) was examined in mice pretreated with alpha-tocopherol (VE) or coenzyme Q10 (CoQ). In VE-pretreated group, the concentrations of aglycone I of the liver (1, 3 and 5 h after the administration), kidney (1 and 3h) and heart (3h) were significantly higher than those in the saline group. The clinical application of VE or CoQ concomitant with anti-tumor drugs especially ADM, requires caution.

Effect of aclarubicin and doxorubicin on rat liver mitochondrial oxidative phosphorylation.

The effects of Aclarubicin (aclacinomycin A; ACM) and Doxorubicin (adriamycin; ADM) on oxidative phosphorylation in rat liver mitochondria were studied in vitro. The state 3 oxygen uptake of mitochondria was reduced by only 2% by 20 microM of ADM, while the same concentration of ACM caused a 67% reduction. When 20 microM of ADM acted on state 4a oxygen uptake of mitochondria, only a slight decrease in state 3, state 4b, dinitrophenol-stimulated respiration and the respiratory control index was observed. In contrast 20 microM of ACM caused significant inhibition of all the above factors when compared with the controls. It was concluded that ACM has strong inhibitory action on the mitochondrial electron transfer system in vitro, and that one can expect functional failure of mitochondria to occur clinically during adverse response to the administration of this drug.

Effect of high dose alpha-tocopherol acetate on the toxicity and tissue distribution of adriamycin (doxorubicin).

The effect of alpha-tocopherol acetate (VE) on the toxicity and tissue distribution of adriamycin (ADM) in mice was studied. After the administration of ADM in 2 doses of 15 mg/kg, mice pretreated with olive oil survived 7.1 +/- 1.0 days, while mice pretreated with VE in ten doses of 500 mg/kg/day (subcutaneously) survived 5.5 +/- 1.7 days (p less than 0.01). The total concentration of ADM and its major metabolite, aglycone I in the liver (1, 3, 5 h), kidneys (1, 3 h), and heart (3 h), as determined by high performance liquid chromatography was significantly higher in the VE-pretreated group (four doses of 500 mg/kg/day) than in the olive oil-pretreated group. The aglycone levels of the VE-pretreated group were significantly higher than those of the olive oil-pretreated group in the liver, kidney and heart, but there was no significant difference between the groups in the levels of the unmetabolized form. Considering these results, the administration of VE concomitant with anti-tumor drugs, including ADM, requires great caution.

Effect of high dose alpha-tocopherol and alpha-tocopherol acetate pretreatment on adriamycin (doxorubicin) induced toxicity and tissue distribution.

When two doses (15 mg/kg) of adriamycin (ADM) were administered to ICR mice pretreated with 500 mg/kg/day of alpha-tocopherol (VE) and alpha-tocopherol acetate (VE-AC) respectively, both the VE and the VE-AC pretreatment groups showed a significant shortening of survival time compared to control group. The concentration of ADM and of total aglycone (AD-NE) was determined in the tissue of mice given a single dose of 15 mg/kg of ADM after pretreatment with 500 mg/kg of VE and VE-AC, respectively, high values were found in liver, kidney and heart tissue compared to the control group. And, particularly the heart tissue of the group pretreated with VE showed significantly higher values of ADM and AD-NE. High AD-NE levels were noted in mouse liver mitochondria (Mt), after pretreatment with both VE and VE-AC, with a significantly higher concentration in the VE-pretreated group. A comparison of the uptake of ADM and AD-NE into mouse Mt pretreated with VE or VE-AC in vitro, showed no difference in the ADM value from that of the control group, but both the VE- and the VE-AC-pretreated groups had significantly higher in AD-NE concentrations compared to the control group.

Protection against adriamycin (doxorubicin)-induced toxicity in mice by several clinically used drugs.

Protective effects of clinically used drugs against adriamycin (ADM)-induced toxicity were studied in ICR mice. The control mice, which were administered 15 mg/kg of ADM twice, survived 7.48 +/- 1.99 days (mean +/- S.D.). The survival times of mice treated with the following drugs, expressed as a percent of that of the control group, were 293.6% for coenzyme Q10 (Co Q10, 2 mg/kg), 402.2% for dextran sulfate (MDS, 300 mg/kg), 121.6% for flavin adenine dinucleotide (20 mg/kg), 236.3% for adenosine triphosphate disodium (50 mg/kg), 213.7% for reduced glutathione (100 mg/kg), 121.6% for phytonadione (50 mg/kg), 155.2% for inositol nicotinate (Ino-N, 500 mg/kg), 335.5% for nicomol (1000 mg/kg), 157.5% for nicardipine (10 mg/kg) and 123.3% for dipyridamol (50 mg/kg). Anti-hyperlipemic agents such as MDS, nicomol, Ino-N and Co Q10 strongly protected against the ADM-induced toxicity, and the mice administered these drugs lived significantly longer than the control mice. The mechanism of the protective effect was discussed.

Effect of dextran sulfate on the survival time and mitochondrial function of Adriamycin (doxorubicin)-treated mice.

The effect of dextran sulfate on the survival time and mitochondrial function of adriamycin (ADM)-treated mice was studied. ADM-induced toxicity in mice was reduced by treatment with dextran sulfate (60, 100, 300, and 600 mg/kg, sc). The optimum dextran sulfate dose for protection against ADM-induced toxicity in mice was about 200 mg/kg/day (sc) and 100 mg/kg/day (po). Groups treated with dextran sulfate (300 mg/kg) had significantly improved mitochondrial function as measured by oxygen uptake of state 3 (p less than 0.01), dinitrophenol-altered respiration (p less than 0.01), and respiratory control index level (p less than 0.01). From these observations, it was concluded that ADM-induced toxicity due to reduced mitochondrial function can be ameliorated by the membrane stabilizing effect of dextran sulfate.