Bends: detection of circulating gas emboli with external sensor.

Circulating gas emboli associated with rapid decompression are detectable in superficial vessels of animals by the use of an ultrasonic Doppler flowmeter transducer which is applied externally.

The treatment of mitochondrial myopathies and encephalomyopathies.

This paper briefly summarizes the results of a long-term, open pharmacotherapy trial in 16 patients with well-characterized mitochondrial disease. Outcome measures included repeated clinical evaluation, 31P-NMR spectroscopy and near-infrared spectroscopy. Treated patients appeared to survive longer with less functional disability and medical complications than typically seen in clinical practice.

In vitro effects of glucocorticoid on mitochondrial energy metabolism.

A systematic study of the effects of the synthetic glucocorticoid, methylprednisolone (MP), on respiration and energy coupling in tightly-coupled mitochondria isolated from rat tissues has been initiated. In intact rat skeletal muscle, liver and heart mitochondria, incubation, in vitro, with greater than or equal to 0.1 mM MP caused inhibition of the state 3 respiratory rates with succinate and NAD-linked substrates. In skeletal muscle and heart mitochondria, the oxidation of succinate was significantly more sensitive to MP than was that of the NAD-linked substrates. No effects were seen at low concentrations (less than 0.02 mM) of MP. In all three tissues, these data together with analysis of the partial reactions of the electron transport chain and steady-state kinetic analysis of cytochrome reduction indicated that in isolated mitochondria high concentrations of MP: (a) inhibit the oxidation of NAD-linked substrates at the level of the respiratory chain between the primary NADH dehydrogenase flavoprotein and coenzyme Q, most likely at the iron-sulfur centers or coenzyme Q-binding proteins of complex I; and (b) inhibit succinate oxidation in intact (but not disrupted) mitochondria, not by inhibiting electron transfer along the respiratory chain, but possibly at the level of succinate transport into the mitochondria. The results of these studies suggest that the therapeutic effects of MP in mitochondrial disease result from indirect effects rather than direct effects on the mitochondrial membrane. More importantly, the absence of an effect at low MP concentrations provides the baseline information needed for further studies to be carried out in vivo.

The treatment of Friedreich's ataxia with amantadine hydrochloride.

Amantadine hydrochloride (AH) was orally administered to 16 patients with Friedreich's ataxia. We evaluated patient response with the functional ataxia scoring scale and calculated a total disability score. The mean percent improvement of the total disability score was 29.5%; for ambulatory patients alone it was 45.5%. No significant side effects were encountered. AH appears to be a safe and effective symptomatic treatment of Friedreich's ataxia.

Cardiomyopathy, mental retardation, and autophagic vacuolar myopathy.

Two brothers had nonobstructive hypertrophic cardiomyopathy, mental retardation, and vacuolar myopathy, and their mother died of cardiopathy at age 31. Seven families with this syndrome have been described; heredity appears to be X-linked dominant or autosomal dominant, with different expressivity in males and females. The biochemical cause of this lysosomal storage disease is unknown.

Fatal farm injuries among young children.

Death certificate data concerning farm-related injury deaths among children 0 to 9 years of age in Wisconsin and Illinois for the period of 1979 to 1985 were reviewed. Average annual farm-related injury death rates were 3.2 per 100,000 rural children in Wisconsin (62 deaths) and 1.5 per 100,000 in Illinois (32 deaths). Rates were three times higher among boys than girls. The occurrence of two harvest-related peaks and the absence of fatality in children less than 1 year of age suggest that presence of children on the farm when supervision is diminished is a key factor in farm-related fatalities. Moving machinery (tractors, wagons, and trucks) was the source of injury in approximately 55% of all deaths. Drowning accounted for 15% of all farm-related deaths. Two fatalities related to gravity box wagons could have easily been prevented with simple safety devices. These findings suggest a need for developing environmental interventions in farms. This will require the allocation of more resources to farm safety programs and a revision of current farm safety legislation.

Effect of N-acetylcysteine on mitochondrial function following traumatic brain injury in rats.

Efficacy of N-acetylcysteine (NAC) in traumatic brain injury (TBI)-induced mitochondrial dysfunction was evaluated following controlled cortical impact injury in rats. Respiratory function and calcium transport of rat forebrain mitochondria from injured and uninjured hemispheres were examined. NAC significantly restored mitochondrial electron transfer, energy coupling capacity, calcium uptake activity and reduced calcium content absorbed to brain mitochondrial membranes when examined 12 h post-TBI if NAC was administered i.p. 5 min before injury or 30 min or 1 h postinjury. Glutathione (reduced form, GSH) levels in brain tissues were decreased at all time points examined over a 14-day observation period, while mitochondrial GSH levels significantly decreased only at 3 days and 14 days following TBI. NAC treatment given within 1 h greatly restored brain GSH levels from 1 h to 14 days and mitochondrial GSH levels from 12 h to 14 days post-TBI. NAC did not show protective effects when given 2 h postinjury. Our data indicate that NAC administered postinjury at an early stage can effectively restore TBI-induced mitochondrial dysfunction and the protective effect of NAC may be related to its restoration of GSH levels in the brain.

Amelioration of mitochondrial function by a novel antioxidant U-101033E following traumatic brain injury in rats.

In the present study, a severe traumatic brain injury (TBI) was produced over the right parietal cortex of rats using the controlled cortical impact injury (CCII) model. TBI perturbed calcium homeostasis and impaired electron transfer and energy coupling activities of forebrain mitochondria isolated from injured hemispheres with a maximal injury at 12-72 h. Efficacy of the blood-brain barrier penetrating antioxidant U-101033E on TBI-induced mitochondrial impairment was evaluated. In the dose-response experiment, two i.v. boluses (vehicle or 1-10 mg/kg of U-101033E) were administered at 5 min and 2h post-TBI. Forebrain mitochondria from each hemisphere were examined at 12 h post-injury. With respect to forebrain mitochondrial dysfunction, the drug showed a bell-shaped dose-response curve with an optimal dose of 3 mg/kg (n = 5, p < 0.05 vs. vehicle). In the time-course experiment, two i.v. boluses of 3 mg U-101033E/kg (the optimal dose) were given at 5 min and 2 h post-injury and forebrain mitochondria were examined at 6 h-14 days post-injury. U-101033E significantly restored electron transfer, energy coupling capacity, and Ca2+ transport capacity during 6 h to 14 days post-injury. Our data indicate that the antioxidant U-101033E administered post-injury at proper dosage can effectively restore TBI-induced mitochondrial dysfunction and support the contention that oxidative stress plays an important role in the pathogenesis of TBI.

Mitochondrial dysfunction and calcium perturbation induced by traumatic brain injury.

Traumatic brain injury (TBI) is associated with primary and secondary injury. A thorough understanding of secondary injury will help to develop effective treatments and improve patient outcome. In this study, the GM model of controlled cortical impact injury (CCII) of Lighthall (1988) was used with modification to induce lateral TBI in rats. Forebrain mitochondria isolated from ipsilateral (IH) and contralateral (CH) hemispheres to impact showed a distinct difference. With glutamate + malate as substrates, mitochondria from the IH showed a significant decrease in State 3 respiratory rates, respiratory control indices (RCI), and P/O ratios. This decrease occurred as early as 1 h and persisted for at least 14 days following TBI. The State 3 respiratory rates, RCI, and P/O ratios could be restored to sham values by the addition of EGTA to the assay mixture. A significant amount of Ca2+ was found to be adsorbed to the mitochondria of both the IH and the CH with higher values seen in the IH. The rate of energy-linked Ca2+ transport in the IH was significantly decreased at 6 and 12 h. These data indicate that CCII-induced TBI perturbs cellular Ca2+ homeostasis and results in excessive Ca2+ adsorption to the mitochondrial membrane, which subsequently inhibits the respiratory chain-linked electron transfer and energy transduction.

Mitochondrial dysfunction after experimental traumatic brain injury: combined efficacy of SNX-111 and U-101033E.

We recently demonstrated that posttraumatic administration of the N-type calcium channel blocker SNX-111 (S) and a novel blood-brain barrier penetrating antioxidant U-101033E (U), significantly alleviated mitochondrial dysfunction induced by traumatic brain injury (TBI) in rats. The present study was designed to determine whether a combination of S and U, which act on different biochemical mechanisms of secondary brain injury, would be more efficacious than either drug alone. Brain mitochondria from injured and uninjured hemispheres were isolated and examined at 12 h post TBI induced by a severe controlled cortical impact injury. S at 1.0 mg/kg significantly increased both State 3 and 4 rates and produced a slight increase in P/O ratio, and there was virtually no change in RCI. U at 1.0 mg/kg did not show any protection. However, the combined treatment of S at 1.0 mg/kg and U at 1.0 mg/kg eliminated the uncoupling effect of S, and restored not only State 3 rates and P/O ratios but also RCI to near sham values. These results provide further evidence that both reactive oxygen species and perturbation of cellular calcium homeostasis participate in the pathogenesis of TBI-induced mitochondrial dysfunction, and support the idea of using combined therapy with lower drug doses.

Gastric mucosal damage due to aspirin and copper aspirinate assessed by gastric mucosal potential difference changes.

When the gastric mucosa is damaged by antiinflammatory agents, such as aspirin, gastric mucosal potential difference (GPD) decreases and may or may not return to predamage values after the agent is removed. The magnitude and time course of the gastric potential difference changes have been suggested as a measure of mucosal damage. Male Sprague-Dawley rats were fasted, anesthetized, and surgically prepared for measurement of GPD by placement of electrodes in the gastric lumen and spleen. Test mixtures of aspirin, copper aspirinate, copper sulfate, or mixtures of aspirin and copper sulfate were administered by gavage, and subsequent changes in GPD were recorded. The area between the extrapolated control (baseline) GPD and the damage GPD was determined. The product of this area and the maximum change in GPD, the Reizindex (RI), was calculated. Values for all copper (II)-containing systems, including those with no aspirin, were significantly greater than aspirin alone. It was concluded that factors other than mucosal damage may contribute to a reduction in GPD and, therefore, an increase in Reizindex.

Impaired cerebral mitochondrial function after traumatic brain injury in humans.

OBJECT: Oxygen supply to the brain is often insufficient after traumatic brain injury (TBI), and this results in decreased energy production (adenosine triphosphate [ATP]) with consequent neuronal cell death. It is obviously important to restore oxygen delivery after TBI; however, increasing oxygen delivery alone may not improve ATP production if the patient's mitochondria (the source of ATP) are impaired. Traumatic brain injury has been shown to impair mitochondrial function in animals; however, no human studies have been previously reported. METHODS: Using tissue fractionation procedures, living mitochondria derived from therapeutically removed brain tissue were analyzed in 16 patients with head injury (Glasgow Coma Scale Scores 3-14) and two patients without head injury. Results revealed that in head-injured patients mitochondrial function was impaired, with subsequent decreased ATP production. CONCLUSIONS: Decreased oxygen metabolism due to mitochondrial dysfunction must be taken into account when clinically defining ischemia and interpreting oxygen measurements such as jugular venous oxygen saturation, arteriovenous difference in oxygen content, direct tissue oxygen tension, and cerebral blood oxygen content determined using near-infrared spectroscopy. Restoring mitochondrial function might be as important as maintaining oxygen delivery.

Improvement in mitochondrial dysfunction as a new surrogate efficiency measure for preclinical trials: dose-response and time-window profiles for administration of the calcium channel blocker Ziconotide in experimental brain injury.

OBJECT: Determining the efficacy of a drug used in experimental traumatic brain injury (TBI) requires the use of one or more outcome measures such as decreased mortality or fewer neurological and neuropsychological deficits. Unfortunately, outcomes in these test batteries have a fairly large variability, requiring relatively large sample sizes, and administration of the tests themselves is also very time consuming. The authors previously demonstrated that experimental TBI and human TBI induce mitochondrial dysfunction. Because mitochondrial dysfunction is easy to assess compared with neurobehavioral endpoints, it might prove useful as an outcome measure to establish therapeutic time windows and dose-response curves in preclinical drug testing. This idea was tested in a model of TBI in rats. METHODS: Animals treated with the selective N-type voltage-sensitive calcium channel blocker Ziconotide (also known as SNX-111 and CI-1009) after cortical impact displayed significant improvement in brain mitochondrial function. When a single intravenous bolus injection of 4 mg/kg Ziconotide was given at different time intervals, ranging from 15 minutes before injury to 10 hours after injury, mitochondrial function was improved at all time points, but more so between 2 and 6 hours postinjury. The authors evaluated the effects on mitochondrial function of Ziconotide at different doses by administering 0.5 to 6 mg/kg as a single bolus injection 4 hours after injury, and found 4 mg/kg to be the optimum dose. CONCLUSIONS: The authors established these time-window profiles and dose-response curves on the basis of mitochondrial outcome measures in a total of 42 rats because there were such low standard deviations in these tests. Establishing similar time-window profiles and dose-response curves by using neurobehavioral endpoints would have required using 114 rats in much more elaborate experiments.

Alterations in cerebral energy metabolism induced by traumatic brain injury.

Energy metabolism of the brain is unique, possessing high aerobic metabolism with no significant capacity for anaerobic glycolysis and limited tissue stores of glucose. A steady supply of oxygen and glucose is essential in order to maintain cerebral function and integrity. Extensive research in experimental and human head injury has been conducted regarding the delivery of oxygen and outcome. This research has provided evidence which indicates that in addition to the availability of oxygen and glucose, other factors, such as perturbation of mitochondrial energy transducing processes which also follow head trauma, play significant roles. In this paper, the salient findings from biochemical studies of experimental and clinical brain injury are summarized and indicate that the mitochondrial respiratory chain-linked oxidative phosphorylation and calcium transport are compromised by trauma-induced brain injury and support the idea that oxidative stress and perturbation of cellular calcium homeostasis play significant roles in traumatic brain injury.

Mitochondrial dysfunction after experimental and human brain injury and its possible reversal with a selective N-type calcium channel antagonist (SNX-111).

We have recently demonstrated in a rat model that traumatic brain injury induces perturbation of cellular calcium homeostasis with an overload of cytosolic calcium and excessive calcium adsorbed on the mitochondrial membrane, consequently the mitochondrial respiratory chain-linked oxidative phosphorylation was impaired. We report the effect of a selective N-type calcium channel blocker, SNX-111 on mitochondrial dysfunction induced by a controlled cortical impact. Intravenous administration of SNX-111 at varying times post injury was made. The concentration titration profile revealed SNX-111 at 4 mg kg-1 to be optimal, and the time window to be administration at 4 h post-injury, in line with that reported on the effect of SNX-111 in experimental stroke. Under optimal conditions, SNX-111 significantly improved the mitochondrial respiratory chain-linked functions, such as the electron transfer activities with both succinate and NAD-linked substrates, and the accompanied energy coupling capacities measured as respiratory control indices (RCI) and ATP synthesis (P/O ratio), and the energy linked Ca2+ transport. In order to assess the applicability of these data to the clinical setting, we have initiated studies with brain tissue which has to be resected during surgical treatment. Five patients suffered from brain trauma, one from intracranial hypertension due to stroke (noninfarcted tissue was taken), and one from epilepsy. Our data revealed that brain mitochondria derived from the patient with intracranial hypertension and the patient with epilepsy were tightly coupled with good respiratory rates with glutamate and malate as substrates, and high P/O ratios. The rates of respiration and ATP synthesis were severely impaired in the brain mitochondria isolated from traumatized patients. These results indicate that investigation of brain mitochondrial functions can be used as a measure for trauma-induced impairment of brain energy metabolism. The time window for the effect of SNX-111 in mitochondrial function and the (preliminary) similarity between mitochondrial dysfunction in experimental animals and humans make the drug appear to be well suited for clinical trials in severe head injury.

Mitochondrial encephalomyopathies.

Mitochondrial encephalomyopathies are neurodegenerative disorders characterized by ragged-red myopathy and encephalopathy, which are recognized with increasing frequency. This article presents the clinical features; pertinent historical, biochemical, and genetic aspects; evaluation; and treatment of mitochondrial encephalomyopathies of childhood and the adult years.

Impaired NADH-CoQ reductase activity in a child with moyamoya syndrome.

A 33-month-old boy with recurrent stroke-like episodes had angiographic features characteristic of moyamoya syndrome. Mitochondrial encephalomyopathy was suspected because of lactic acidosis and ptosis. Studies of oxidative metabolism on isolated skeletal muscle mitochondria revealed impairment of NADH-coenzyme Q reductase activity. Mitochondrial metabolic disorders may cause moyamoya syndrome when other known associated factors are absent.

Partial cytochrome b deficiency and generalized dystonia.

An 18-year-old female had clinical features of idiopathic torsion dystonia with bilateral hypodense putaminal lesions on computed tomography. Mitochondrial encephalomyopathy was suspected because of persistent lactic acidemia and myopathy. Studies of oxidative metabolism on isolated skeletal muscle mitochondria revealed partial cytochrome b deficiency indicating a defect in the cytochrome b- c1 complex. This finding represents a unique, multisystem syndrome of progressive dystonia, putaminal degeneration, myopathy, and mitochondrial cytochrome b deficiency. Mitochondrial metabolic disorders may be a cause of torsion dystonia when other known associated factors are absent.

Alcohol and drug use among homosexual men and women: epidemiology and population characteristics.

Homosexual men and women have been described as at high risk for alcohol and drug abuse, due to psychosocial variables such as stress levels or the cultural importance of bar settings. However, there are few actual data in this regard. This paper presents the findings of a large (n = 3400) survey of a homosexual population regarding population characteristics and patterns of alcohol and drug use. Psychosocial variables that may account for substance use patterns both generally and in this population are discussed in an accompanying paper. Substantially higher proportions of the homosexual sample used alcohol, marijuana, or cocaine than was the case in the general population. Contrary to other reports, this was not accompanied by higher rates of heavy use, although homosexuals did show higher rates of alcohol problems. In the general population women consume less drugs and alcohol than do men, and substance use substantially declines with age. Neither of these patterns were found for the homosexual sample, thus creating overall higher rates of substance abuse. This may reflect differences between homosexuals and the general population in their adherence to sex-role stereotypes and age-related social role changes, as well as culturally specific stressors and vulnerability to substance use.

Psychosocial and cultural factors in alcohol and drug abuse: an analysis of a homosexual community.

Homosexual men and women may be at risk for alcohol and drug abuse due to psychosocial variables such as drinking styles, stress, or the cultural importance of bars. The study of psychosocial variables in homosexual culture may help us understand how they operate generally. This paper describes the findings of a large (n = 3400) survey of homosexual population. The core hypothesis was that stress and other psychosocial variables have their primary effects among people made vulnerable to substance abuse by individual expectancies and/or cultural values. Tension reduction expectancies of alcohol effects had substantial effects on alcohol and drug abuse, as did the use of bars as a social resource, a vulnerability variable more specific to urban homosexual culture. Further, stress affected alcohol-drug problems only among people who were "vulnerable" via expectancies and values, and both high risk styles of substance use and simple consumption levels had much stronger effects on problems among vulnerable respondents, thus supporting the stress-vulnerability perspective. Individual differences in social role status was related to alcohol and drug problems, and may explain differences between homosexual and general populations.