Influence of nonionic organic solutes on various reactions of energy conservation and utilization

Comparing two local anesthesia techniques for extracorporeal shock wave lithotripsy

OBJECTIVES

To evaluate the efficacy of a eutectic mixture of local anesthetics (EMLA) cream compared with dimethyl sulfoxide (DMSO) with lidocaine during extracorporeal shock wave lithotripsy (ESWL) in a prospective randomized study.

METHODS

Of 167 patients, 85 received 10 g of EMLA cream (EMLA group) and 82 received 10 g of 40% DMSO (DMSO group) with an amount of lidocaine equal to that in the lidocaine gel, applied to the skin of the flank at the area of entry of the shock wave marked by the urologist. A second-generation lithotriptor Siemens Lithostar was used. The degree of pain was rated by the patients using a 10-point visual analog scale.

RESULTS

In 80 patients in the EMLA group (94%), the entire procedure was performed with no, minor, or tolerable pain after the application of EMLA cream (pain score 5.2 +/- 1.3). In 5 EMLA patients (6%), EWSL was interrupted because of intolerable pain. Of the 82 DMSO patients, 80 (98%) underwent the entire procedure with no, minor, or tolerable pain after the application of DMSO with lidocaine (pain score 3.7 +/- 1.1). In 2 DMSO patients (2%), EWSL was interrupted because of intolerable pain. The pain scores were significantly lower for the DMSO group than for the EMLA group (P = 0.011).

CONCLUSIONS

Our findings have indicated that the pain scores were significantly lower for the DMSO group than for the EMLA group. In addition to the local anesthetic effect of DMSO, diuretic, anti-inflammatory, muscle relaxant, and hydroxyl radical scavenger effects can be important for patients undergoing ESWL. These effects should be evaluated with new studies of patients undergoing ESWL.

Prevention of hepatic cirrhosis in rats by hydroxyl radical scavengers

BACKGROUND/AIMS

Reactive oxygen species and oxidative stress were implicated in hepatic stellate cell activation and liver fibrosis. The aim of the present study was to examine whether the administration of free radical scavengers in vivo would prevent experimentally-induced hepatic cirrhosis in rats.

METHODS

Cirrhosis was induced by administration of thioacetamide (TAA; 200 mg/kg, i.p.) twice/week, for 12 weeks. Rats were treated concurrently with either dimethylsulfoxide (DMSO; 4 g/kg, s.c. or p.o.) or dimethylthiourea (DMTU; 200 mg/kg i.p.) three times a week.

RESULTS

Liver fibrosis (histopathological score, spleen weight, and hepatic hydroxyproline) was abolished in rats treated with TAA and either DMSO or DMTU (P < 0.001). Accordingly, the hepatic expression of alpha smooth muscle actin, tissue inhibitor of metalloproteinase 2 and collagen alpha1 (I) gene were inhibited. The hepatic level of methane-sulfinic acid (produced by the interaction of DMSO with hydroxyl radicals) was increased in rats treated with TAA + DMSO (P = 0.0005) and decreased after pretreatment of these rats with DMTU (P = 0.008). However, the hepatic levels of malondialdehyde, lipid peroxides and protein carbonyls were not lower in the DMSO- and DMTU-treated groups.

CONCLUSIONS

The administration of free radical scavengers prevented the development of TAA-induced liver cirrhosis probably associated with decreased oxidative stress.

The hydroxyl radical scavengers dimethylsulfoxide and dimethylthiourea protect rats against thioacetamide-induced fulminant hepatic failure

BACKGROUND/AIMS

Reactive oxygen species, proinflammatory cytokines, glutathione depletion and nitric oxide have all been implicated in the pathogenesis of fulminant hepatic failure. The aim of the present study was to examine the respective roles of these factors in the pathogenesis of thioacetamide-induced fulminant hepatic failure in rats.

METHODS

Fulminant hepatic failure was induced by 3 consecutive intraperitoneal injections of thioacetamide (400 mg/kg) at 24-h intervals. Rats were pretreated with one of the following agents: the free radical scavengers dimethylsulfoxide (4 g/kg every 6 h) or dimethylthiourea (200 mg/kg every 12 h), the glutathione donor, N-acetylcysteine (130 or 200 mg/kg every 6 h), or the anti-tumor necrosis factor-alpha agents pentoxifylline (100 and 200 mg/kg) and soluble tumor necrosis factor receptor (100 or 1000 microg/rat). The nitric oxide synthase inhibitor N-mono-methyl arginine ester (L-NAME, 0.1 mg/ml) was administered in the drinking water, starting 7 days prior to thioacetamide administration.

RESULTS

Serum levels of liver enzymes, blood ammonia and prothrombin time and the stage of hepatic encephalopathy were significantly improved in rats treated with dimethylsulfoxide or dimethylthiourea compared to the other treatment groups (p<0.001). Liver histology and the survival rate in these rats were not adversely affected by thioacetamide administration (p<0.001), while in all the other treatment groups those parameters were similar to control rats with fulminant hepatic failure. Furthermore, dimethylsulfoxide ameliorated liver damage and improved survival even when its administration was initiated 8 and 16 h after the first thioacetamide injection. The hepatic concentration of methanesulfinic acid, which is produced after direct interaction of dimethylsulfoxide with hydroxyl radicals, was increased five-fold in rats treated with thioacetamide+dimethylsulfoxide (p<0.001), suggesting a role for hydroxyl radical scavenging in the protection from fulminant hepatic failure in this model. In the group of thioacetamide-treated rats that were pretreated with L-NAME, liver enzymes, blood ammonia levels and the mortality rate were higher than in the control group, treated with thioacetamide only.

CONCLUSIONS

In thioacetamide-induced fulminant hepatic failure, the hydroxyl radical scavengers dimethylsulfoxide and dimethylthiourea prevent liver injury. Neither N-acetylcysteine nor antagonists of tumor necrosis factor-alpha are protective in this rat model. Inhibition of nitric oxide formation aggravates liver damage and reduces the survival of rats with thioacetamide-induced liver damage.

Response of the electrochromic dye, merocyanine 540, to membrane potential in rat liver mitochondria

Merocyanine binds extensively to rat liver mitochondria in spite of the presence of a sulfonic acid group which would suggest only limited penetration through the membrane. Passive binding shows both tight and weak binding components and is dependent on salt concentration and ionic strength in accord with the Gouy-Chapman theory. The binding of merocyanine to mitochondria is accompanied by both a fluorescence enhancement and a spectral shift. Induction of an electrical field by either respiration or K+ diffusion potential results in a partial reversal of the spectral shift seen on dye binding. At low temperature, the merocyanine spectral response to an electrical field is biphasic, consisting of a fast phase with a t1/2 of less than 1 sec at 15 degrees C and a slower phase which may vary considerably in rate and extent with conditions. The spectral shift during the two phases appears similar, but differ in sensitivity to ionic strength and temperature. The spectral shift during the fast phase at 15 degrees C indicates that the major component is a decrease in bound monomer and an increase in the aqueous dimer, indicating an "on-off" mechanism. It is suggested that the fast and slow phases of the merocyanine response may be due to two different populations of dye, possibly located at the outer and inner surfaces, respectively, of the mitochondrial membrane. The electrophoretic movement of the dye located in the membrane interior would result in the temperature-sensitive slow phase response. Demonstration of the proportionality of the fast phase response to the magnitude of the membrane potential suggests the usefulness of merocyanine in studies with mitochondrial systems.

The bioenergetics of mitochondria after cryopreservation

The functional characteristics of rat liver mitochondria after cryopreservation with and without the addition of the cryoprotectant dimethyl sulfoxide (Me2SO) were evaluated. As criteria of functional integrity, polarographic measurements of substrate-linked oxygen consumption and luminescent assay of adenosine triphosphate (ATP) synthesis were considered before and after cryopreservation. The results demonstrated that mitochondrial damage after freezing was indicated by the polarographic studies but was not evident when ATP synthesis was considered. Me2SO present during cryopreservation was partially protective for mitochondrial substrate-linked oxygen consumption; however, simple exposure to and dilution from Me2SO effected some changes in mitochondrial function.

The relevance of cryoprotectant "toxicity" to cryobiology

Cryoprotective agents are essential for the cryopreservation of almost all biological systems. These additives, however, do not usually permit 100% survival after freezing and thawing, though from a theoretical point of view they should be able to fully suppress all known types of freezing injury. In view of the known biological and physicochemical effects of cryoprotectants, it is suggested that the toxicity of these agents is a key limiting factor in cryobiology. Not only does this toxicity prevent the use of fully protective levels of additive, but it may also be manifested in the form of cryoinjury over and beyond the cryoinjury due to classical causes. Evidence for this extra injury ("cryoprotectant-associated freezing injury") is reviewed. It is suggested that better suppression of toxicity is possible and will lead to advances in cryopreservation.

Pharmacology of DMSO

A wide range of primary pharmacological actions of dimethyl sulfoxide (DMSO) has been documented in laboratory studies: membrane penetration, membrane transport, effects on connective tissue, anti-inflammation, nerve blockade (analgesia), bacteriostasis, diuresis, enhancement or reduction of the effectiveness of other drugs, cholinesterase inhibition, nonspecific enhancement of resistance to infection, vasodilation, muscle relaxation, antagonism to platelet aggregation, and influence on serum cholesterol in experimental hypercholesterolemia. This substance induces differentiation and function of leukemic and other malignant cells. DMSO also has prophylactic radioprotective properties and cryoprotective actions. It protects against ischemic injury.

Role of dimethyl sulfoxide in prostaglandin-thromboxane and platelet systems after cerebral ischemia

Direct and empirical evidence indicates that intravenous administration of DMSO can arrest or reverse cerebral and extracerebral ischemia following experimental or clinical injury. When the delivery of oxygen and nutrients to the tissue is deficient or unavailable (as in ischemia), cell damage or death with all its attending pathological consequences becomes an end-point. In the brain, this equates to build-up of intracranial pressure, impairment of neural transmission to vital centers, and loss of function or death. We have reviewed a number of studies that show the usefulness of DMSO in preventing significant pathology from developing in various experimental injury models and in clinical subjects. We have proposed that the action of DMSO in biochemical, morphological, and functional subsystems is not specific but rather interactive. Figure 5 illustrates this point. Any one effect by DMSO on these subsystems that does not affect the others seems highly unlikely. How DMSO or similar drugs affect these systems, could provide important clues in clarifying the pathogenesis of ischemia and in reducing its severity. We conclude from the available evidence that ischemic injury is a dynamic process constantly promoting biochemical, vascular, and morphological changes and that DMSO is able to intervene at various levels of this pathochemical cascade. DMSO may do this by its ability to normalize tissue perfusion when this is lacking or impaired. We speculate that this effect by DMSO is predominantly on the PG-TX and platelet systems, since these appear to be the most important candidates implicated in vessel occlusion and spasm. It is further concluded from the available and theoretical evidence presented here, that clinical trials using DMSO in cerebral and extracerebral organ ischemia should be designed in order to evaluate the efficacy of this compound to other antithrombogenic therapies. It is reasonable to assume that DMSO may provide a primary approach to the treatment of cerebral, myocardial, renal, and platelet-induced ischemic disorders.

Spore germination in Dictyostelium discoideum. II. Effects of dimethyl sulfoxide on post-activation lag as evidence for the multistate model of activation

Mutant spores of Dictyostelium discoideum, strain SG-10, differ from wild type spores in their ability to spontaneously germinate, to be activated with 5% Dimethyl Sulfoxide (DMSO), and to be deactivated with 0.2 M sucrose. Both heat-activated wild type and mutant spores began to swell after a lag of 60-75 min at ambient temperature. Suspension of heat activated spores in 5% DMSO resulted in blockage of spore swelling and a concomitant severe inhibition of respiration; removal of 5% DMSO allowed resumption of respiration and the spores began to swell after a lag of only 15 min. It was concluded that 5% DMSO allowed the early reactions (M) to proceed but blocked the later reactions (R) of post-activation lag. Treatment of one day old spores with 20% DMSO solution for 30-120 min quantitatively activated the population. The post-activation lag time was directly dependent on the time of 20% DMSO treatment. Spores activated with 20% DMSO treatment could be deactivated by incubation at 0 degrees C; the spores most quickly deactivated at 0 degrees C were those within 10 min of swelling. Mitochondrial transport inhibitors such as azide and cyanide caused deactivation in an analogous manner. It is hypothesized that spores proceed to the second portion of the lag phase called (R) before the environment determines if dormancy is reimposed or if germination will proceed. The sensitive strain (SG-10) showed a greater degree of "damage" than the wild type after supraoptimal treatment with 40% DMSO. The spores became more resistant with age to the "damaging" action of 40% DMSO. All the observed effects of DMSO treatment were compatible with our multistate model of activation which suggests that the early portion of the lag phase (M) may involve a relative uncoupling of oxidative phosphorylation while the later portion (R) may require tight coupling.