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The postnatal development of the complexes of the electron transport chain in mitochondria isolated from rat brain synaptosomes was investigated. Synaptosomal brain mitochondria were isolated from rats aged 10-60 days, and the activities of mitochondrial complex I, complex II-III, complex IV and complex V were measured. There was a significant increase in the activity of II-III from day 10 to day 15 and complex IV from day 10 to day 21, thereafter the activities of complexes I-III and IV did not change significantly. The activity of complex I did not change significantly during the period 10-60 days post partum. In synaptic mitochondria, complex V activity was higher than in non-synaptic mitochondria, whereas the activity of complex I was lower than in non-synaptic mitochondria. These data show that the complexes of the respiratory chain within synaptic mitochondria have activities different from those of non-synaptic mitochondria and may have major implications for the relative susceptibility of mitochondria in different brain cell types to neurotoxins such as MPP+, hypoxic/ischaemic damage and oxidative stress.

The effect of depletion of reduced glutathione (GSH) on brain mitochondrial function and N-acetyl aspartate concentration has been investigated. Using pre-weanling rats, GSH was depleted by L-buthionine sulfoximine administration for up to 10 days. In both whole brain homogenates and purified mitochondrial preparations complex IV (cytochrome c oxidase) activity was decreased, by up to 27%, as a result of this treatment. In addition, after 10 days of GSH depletion, citrate synthase activity was significantly reduced, by 18%, in the purified mitochondrial preparations, but not in whole brain homogenates, suggesting increased leakiness of the mitochondrial membrane. The whole brain N-acetyl aspartate concentration was also significantly depleted at this time point, by 11%. It is concluded that brain GSH is important for the maintenance of optimum mitochondrial function and that prolonged depletion leads also to loss of neuronal integrity. The relevance of these findings to Parkinson's disease and the inborn errors of glutathione metabolism are also discussed.

The efficacy of cystine, ascorbate and trolox, a vitamin E analogue, at protecting against nitric oxide-mediated mitochondrial complex IV damage has been investigated in cultured astrocytes. Of these compounds, only trolox afforded protection. It is suggested that lipid peroxidation is responsible for nitric oxide-mediated mitochondrial damage and that inhibitors of this process may be of therapeutic benefit in conditions where excessive nitric oxide production is implicated.

Some NMR resonances which have previously been observed but not identified in mammalian brain tissue extracts have been shown to arise from ethanolamine. This conclusion is drawn from a systematic study of the perchloric acid extracts of rodent brain tissue in which several NMR experiments were used to assign the peaks unambiguously. The extraction procedure used in this work gave samples with highly reproducible spectra, and ethanolamine was observed in all our extract samples. A localized increase in the concentration of ethanolamine was seen in the spectra of extracts produced from a cerebral infarct induced by occlusion of the middle cerebral artery in the rat.

The eubacterial genus Rickettsia belongs to the alpha subgroup of the phylum Proteobacteria. This genus is usually divided into three biotypes on the basis of vector host and antigenic cross-reactivity characteristics. However, the species Rickettsia bellii does not fit into this classification scheme; this organism has characteristics common to both the spotted fever group and the typhus group biotypes and also exhibits some unique features. Sequences of the 16S rRNA and 23S rRNA genes from Rickettsia rickettsii (spotted fever group), Rickettsia prowazekii (typhus group), and R. bellii were studied to determine the position of R. bellii in the rickettsial classification scheme. The 23S rRNA gene sequences described in this paper are the first 23S rRNA sequences reported for any member of the Rickettsiaceae. The 23S rRNA gene contains substantially more phylogenetic information than is contained in the 16S rRNA sequences, and the 23S rRNA gene sequence has diverged about 1.9 times faster in the three Rickettsia species which we studied. Taken together, the molecular data obtained from the two genes indicate that R. bellii is not a member of either the spotted fever group or the typhus group; rather, this organism appears to be the product of a divergence which predates the separation of the genus into the spotted fever group and the typhus group. Consequently, different combinations of the ancestral characteristics retained by R. bellii have been retained in the more derived lineages of the genus.(ABSTRACT TRUNCATED AT 250 WORDS)

Data from all patients registered blind from diabetic retinopathy in Avon during a 16 month period were analysed with regard to management before hospital referral. The main findings were: 50% of the patients had no screening for retinopathy and were known to be diabetic; 25% were regularly screened for retinopathy (three quarters by local opticians); 22% were newly diagnosed as diabetic at the time of hospital referral. The degree of visual loss at the time of first hospital attendance was found to be marked (average 4.4 Snellen lines of acuity) but was not significantly different for different sources of referral. Only one eye of one patient had normal acuity at first attendance and 88% had lost two or more lines; 72% of registrations were a result of diabetic maculopathy. Delay from waiting for hospital appointments did not contribute significantly to the outcome in the group of patients studied.

The Ca(2+)-independent form of nitric oxide synthase was induced in rat neonatal astrocytes in primary culture by incubation with lipopolysaccharide (1 microgram/ml) plus interferon-gamma (100 U/ml), and the activities of the mitochondrial respiratory chain components were assessed. Incubation for 18 h produced 25% inhibition of cytochrome c oxidase activity. NADH-ubiquinone-1 reductase (complex I) and succinate-cytochrome c reductase (complex II-III) activities were not affected. Prolonged incubation for 36 h gave rise to a 56% reduction of cytochrome c oxidase activity and a 35% reduction in succinate-cytochrome c reductase activity, but NADH-ubiquinone-1 reductase activity was unchanged. Citrate synthase activity was not affected by any of these conditions. The inhibition of the activities of these mitochondrial respiratory chain complexes was prevented by incubation in the presence of the specific nitric oxide synthase inhibitor NG-monomethyl-L-arginine. The lipopolysaccharide/interferon-gamma treatment of the astrocytes produced an increase in glycolysis and lactate formation. These results suggest that inhibition of the mitochondrial respiratory chain after induction of astrocytic nitric oxide synthase may represent a mechanism for nitric oxide-mediated neurotoxicity.

The effects of 1-methyl-4-phenylpyridinium (MPP+) on the oxygen consumption, ATP production, H2O2 production, and mitochondrial NADH-CoQ1 reductase (complex I) activity of isolated rat brain mitochondria were investigated. Using glutamate and malate as substrates, concentrations of 10-100 microM MPP+ had no effect on state 4 (-ADP) respiration but decreased state 3 (+ADP) respiration and ATP production. Incubating mitochondria with ADP for 30 min after loading with varying concentrations of MPP+ produced a concentration-dependent decrease in H2O2 production. Incubation of mitochondria with ADP for 60 min after loading with 100 microM MPP+ caused no loss of complex I activity after washing of MPP+ from the mitochondrial membranes. These data are consistent with MPP+ initially binding specifically to complex I and inhibiting both the flow of reducing equivalents and the production of H2O2 by the mitochondrial respiratory chain, without irreversibly damaging complex I. However, mitochondria incubated with H2O2 in the presence of Cu2+ ions showed decreased complex I activity. This study provides additional evidence that cellular damage initiated by MPP+ is due primarily to energy depletion caused by specific binding to complex I, any increased damage due to free radical production by mitochondria being a secondary effect.

The purpose of this study was to determine the extracellular concentrations of N-acetylaspartate (NAA) in the rat cerebral cortex, striatum, and hippocampus of halothane-anaesthetised rats by intracerebral microdialysis, and to examine the effects of high K(+)-induced local depolarisation, which provokes synchronous neurotransmitter release, cell swelling, and acid-base changes. Basal levels of NAA in the extracellular fluid (ECF) were determined by the zero net flux method. Tissue levels of NAA in the cortex, striatum, and hippocampus were 8.4, 5.7, and 7.2 mmol/kg, respectively. The corresponding extracellular concentrations of NAA were much lower (35.1, 83.7, and 23.0 microM). High tissue/ECF concentration ratios may suggest little release or leakage of NAA under basal conditions, and potent reuptake mechanisms for NAA in the cellular membrane of CNS cells. There was no change in ECF NAA during K(+)-induced local depolarising stimuli produced in the striatum, but NAA levels consistently increased after the K+ stimuli, irrespective of whether or not Ca2+ was present in the perfusion medium. These data confirm that NAA is not a neurotransmitter and suggest strongly that NAA is not directly involved in the release and reuptake or metabolism of neuroactive compounds. The increase of NAA in the ECF immediately after K+ stimulation may reflect an involvement in brain osmoregulation and/or acid-base homeostasis.

We report the isolation of cDNA clones encoding the somatic form of the E1 alpha subunit of the pyruvate dehydrogenase complex of rat. The deduced amino acid sequence has 99.5, 98, and 97% identity, respectively, with the orthologous proteins of mouse, human, and pig and 98.5% identity with a rat E1 alpha sequence reported previously. The cDNAs isolated in this and earlier studies predict different E1 alpha subunit mRNA sizes and amino acid sequences. These differences have been investigated by PCR, northern blot hybridization, and RNase protection. We have used our E1 alpha cDNA, in conjunction with cDNA probes to the E1 beta, E2, and E3 catalytic subunits of rat pyruvate dehydrogenase complex and also to rat citrate synthase, to perform RNase protection assays of developing rat whole brain RNA. The results show a 2.5-fold increase in the concentration of each of the subunit mRNAs and a 1.2-fold increase in citrate synthase mRNA from late foetal stage to 5 days post partum. Thereafter, the mRNA levels remained constant. These data indicate that the respective six- and threefold increases in the amounts of pyruvate dehydrogenase complex and citrate synthase found to occur in rat brain between birth and adulthood are mediated principally by translational and/or posttranslational mechanisms.

The postnatal development of the complexes of the electron transport chain in isolated rat brain mitochondria were investigated. Nonsynaptosomal brain mitochondria were isolated from rats aged 1-60 days, and the activities of mitochondrial complexes I, II-III, IV, V and citrate synthase were measured. There was a significant increase in the activity of complex I from postnatal day 1 to day 21, and in the activities of complex II-III, complex IV and citrate synthase from postnatal day 1 to day 60. In contrast, the activity of complex V increased significantly between postnatal day 1 and day 10 where it attained adult levels. These data are consistent with the increasing demand for mitochondrial ATP production as the brain develops and as aerobic glycolysis becomes the major pathway for energy production.

Nucleotide sequence comparisons were used to investigate the evolution of P transposable elements and the possibility that horizontal transfer has played a role in their occurrence in natural populations of Drosophila and other Diptera. The phylogeny of P elements was examined using published sequences from eight dipteran taxa and a new, partial sequence from Scaptomyza elmoi. The results from a number of different analyses are highly consistent and reveal a P-element phylogeny that contradicts the phylogeny of the species. At least three instances of horizontal transfer are necessary to explain this incongruence, but other explanations cannot be ruled out at this time.

cDNA clones encoding the testis-specific form of the rat pyruvate dehydrogenase complex E1 alpha subunit have been isolated. Comparison of the predicted amino acid sequence with those of the somatic and testis-specific E1 alpha forms of man and mouse and the somatic E1 alpha form of rat indicates the change of a serine residue, believed to be phosphorylated in vivo by pyruvate dehydrogenase E1 alpha-specific kinase, to an alanine at position 233. The implications of this change are discussed. Northern blot analysis and RNase protection assays indicate that the expression of mRNA encoding testis-specific E1 alpha subunit is restricted to testis whereas mRNA for the somatic form is found in all tissues analyzed, albeit in very small amounts in testis.

This article presents a format of aeromedical decision-making used in neurology cases referred to a U.S. Navy Special Board of Flight Surgeons (SBFS) from 1988 to 1990. The format consists of a series of questions addressing aeromedical concerns, an aeromedical disposition flowchart, and a decision analysis tree. Decision Analysis is a tool used in clinical medicine to assist decision-making under conditions of uncertainty. The Decision Analysis approach may be applied to complex aeromedical disposition questions that face flight surgeons. The concept of risk assessment as it applies to decision-making and aeromedical disposition is discussed. The outcome of 24 neurology cases referred for aeromedical disposition are presented.

The metabolic capability for the complete oxidation of glucose, i.e. aerobic glycolysis, is highly developed in the brains of neurologically mature (precocial) species at birth, whereas this activity is severely limited in the brains of neurologically immature (non-precocial) species such as the rat and human. The latter utilize a mixture of glucose and ketone bodies for synthetic and energetic activities and the advent of neurological competence associated with the capability for complete dependence on and oxidation of glucose must await the development of key enzymes such as the pyruvate dehydrogenase complex (PDHC). A similar relationship appears to exist with respect to the development of neurological maturity of different brain regions in a single species, the rat. The development of the enzymes of energy metabolism of neonatal rat brain will be discussed with respect to the energy fuels available to the neonatal brain. In particular mechanisms by which the PDHC develops in neonatal brain will be evaluated. Evidence suggests that this is due to a specific increase in enzyme protein in contrast to a general increase in mitochondrial activity.

Loss of spatial awareness has been implicated as a direct causal factor in 4-10% of serious aircraft mishaps and 10-20% of fatal aircraft mishaps (7). Spatial disorientation in flight usually results from misperception of visual, vestibular, or proprioceptive cues. Pathologic causes have rarely been implicated. A student naval aviator with recurrent loss of spatial awareness due to a defective vestibulo-ocular reflex (VOR), presumably from vestibular neuronitis in adolescence, is reported. His chief complaint, an inability to focus on the instrument panel during turbulent instrument meteorological conditions (IMC), resulted in spatial disorientation and adverse flight attitude. A simple test of visual-vestibular interaction, the dynamic visual acuity test, could identify a defective vestibulo-ocular reflex in aviation personnel. An absent or defective vestibulo-ocular reflex has potential for disorientation in instrument flight. A comprehensive vestibular function test battery is indicated in individuals with recurrent or overwhelming spatial disorientation who fail a screening dynamic visual acuity test. The aeromedical disposition of vertigo and dysequilibrium is discussed.

Background and Purpose: Victims of air embolism often recover rapidly on hyperbaric treatment then deteriorate again, even if hyperbaric treatment is continued. In previous animal experiments, lidocaine has been shown to improve recovery of somatosensory evoked response amplitude after air embolism. However, animals in these experiments rarely deteriorated. We have shown that the induction of air embolism and transient hypertension in canines produces deterioration despite hyperbaric treatment, and we decided to test the effect of lidocaine on somatosensory evoked potential recovery and cerebral blood flow in this model., Methods: Dogs were treated with repeated doses of lidocaine or equivalent volumes of saline during hyperbaric therapy after internal carotid air embolism and transient hypertension. The investigators were unaware of treatment group assignment during the experiments. The amplitude of the median nerve somatosensory evoked potential and cerebral blood flow measured with carbon-14-labeled iodoantipyrine autoradiography were used to assess effect of therapy., Results: Lidocaine-treated dogs recovered 60 +/- 10% (mean +/- 95% confidence limits) of the baseline somatosensory evoked potential amplitude 220 minutes after air embolism; saline-treated dogs recovered 32 +/- 10% (a significant difference at p less than 0.01). Lidocaine-treated dogs also had higher cerebral blood flow values than saline-treated dogs 220 minutes after air embolism., Conclusions: Lidocaine ameliorated the delayed deterioration of evoked potential associated with air embolism and hypertension in this canine model. The improved cerebral blood flow may be a mechanism of action of lidocaine or an associated effect of improved neuronal survival.

Chronic administration of diphenylene iodonium (DPI) to rats has been shown to model the characteristics of mitochondrial myopathy. Using this model the efficacy of menadione therapy has been assessed. Menadione treatment of rats injected with DPI was associated with improved weight gain and increased survival rate. This was accompanied by an improvement in muscle function as judged by analysis of isometric twitch tension of the gastrocnemius muscle (1 Hz for 20 min). The decline in phosphocreatine (PCr) levels in the gastrocnemius muscle during stimulation and delayed recovery in PCr after stimulation were similar in the menadione treated and untreated models. Menadione treatment of the DPI model resulted in a resting intramuscular pH significantly lower than control or untreated DPI rats, but a similar decline in intramuscular pH to the DPI rats during stimulation. The changes in metabolite levels were broadly similar in both the menadione treated and untreated DPI models following stimulation, although the changes, except for increased lactate concentration, were generally less marked in the menadione-treated DPI model.

Polypeptides of beef heart mitochondrial complex I were isolated from 15 mg of solubilized beef heart mitochondria using antibodies immobilized on an agarose chromatography column. The preparation was examined by SDS electrophoresis and Western blotting using affinity-purified antibodies to complex I and compared to beef heart complex I purified according to the conventional method of Hatefi and Rieske. There was a high degree of homology between the two preparations as judged by SDS-polyacrylamide electrophoresis and by immunoblotting with seven affinity-purified antibodies to various complex I subunits. This method could be applied to the preparation of complex I subunits from small samples such as human muscle biopsy specimens.

Twenty-three patients with mitochondrial myopathies and mitochondrial DNA deletions in muscle were studied by means of deletion mapping and sequencing, histochemistry and polarography. Histochemistry showed significantly less focal cytochrome oxidase deficiency relative to number of ragged red fibres when the deletion did not involve reading frames for cytochrome oxidase subunits. Polarography in such patients showed defects exclusively involving complex I, in contrast to the others with larger deletions who generally had more diffuse respiratory chain defects. Analysis of other published histochemical data showed similar findings to our own. It is concluded that translation of a proportion of deleted mitochondrial DNAs occurs in at least some patients with mitochondrial DNA deletions, implying that deleted and normal mitochondrial genomes share transfer RNAs within mitochondria in such cases.

The utilization of lactate, glucose, 3-hydroxybutyrate, and glutamine has been studied in isolated brain cells from early newborn rats. Isolated brain cells actively utilized these substrates, showing saturation at concentrations near physiological levels during the perinatal period. The rate of lactate utilization was 2.5-fold greater than that observed for glucose, 3-hydroxybutyrate, or glutamine, suggesting that lactate is the main metabolic substrate for the brain immediately after birth. The apparent Km for glucose utilization suggested that this process is limited by the activity of hexokinase. However, lactate, 3-hydroxybutyrate, and glutamine utilization seems to be limited by their transport through the plasma membrane. The presence of fatty acid-free bovine serum albumin (BSA) in the incubation medium significantly increased the rate of lipogenesis from lactate or 3-hydroxybutyrate, although this was balanced by the decrease in their rates of oxidation in the same circumstances. BSA did not affect the rate of glucose utilization. The effect of BSA was due not to the removal of free fatty acid, but possibly to the binding of long-chain acyl-CoA, resulting in the disinhibition of acetyl-CoA carboxylase and citrate carrier.

There is strong inferential evidence for recent horizontal gene transfer of the P (mobile) element to Drosophila melanogaster from a species of the Drosophila willistoni group. One potential vector of this transfer is a semiparasitic mite, Proctolaelaps regalis DeLeon, whose morphology, behavior, and co-occurrence with Drosophila are consistent with the properties necessary for such a vector. Southern blot hybridization, polymerase chain reaction (PCR) amplification, and DNA sequencing showed that samples of P. regalis associated with a P strain of D. melanogaster carried P element sequences. Similarly, Drosophila ribosomal DNA sequences were identified in P. regalis samples that had been associated with Drosophila cultures. These results have potentially important evolutionary implications, not only for understanding the mechanisms by which genes may be transferred between reproductively isolated species, but also for improved detection of some host-parasite and predator-prey relationships.

In depolarised anoxic synaptosomes, in which lactate production was significantly raised compared with normoxic conditions, calcium uptake, net acetylcholine release, and the intrasynaptosomal calcium concentration were all significantly lowered. In contrast, lactate production in synaptosomes incubated under aglycaemic- and ischaemic-type conditions was significantly lower and basal calcium uptake, acetylcholine release, and intrasynaptosomal calcium concentration were elevated compared with normoxia. In addition, the increase in intrasynaptosomal calcium concentration under the ischaemic-type condition appeared to be greater than could be accounted for by the rise in calcium uptake alone. Intrasynaptosomal pH reflected the lactate production under each condition investigated. Addition of exogenous lactate to normoxic synaptosomes mimicked the effects observed in anoxia, suggesting that lactate itself may have blocked the calcium uptake, inhibiting the rise in intrasynaptosomal calcium and acetylcholine release occurring in depolarised anoxic synaptosomes. When lactate was added to ischaemic synaptosomes, the large rise in intrasynaptosomal calcium concentration, calcium uptake, and acetylcholine release were decreased, suggesting that lactate may have a protective role in preventing cell death by calcium overload under ischaemic-type conditions. Evidence is presented to suggest that the effect of L-lactate was due to the lactate moiety itself rather than the associated acidosis.

Previously, we have used the isolated perfused rat brain (IPRB) to demonstrate authentic cerebral synthesis of the lipid mediator platelet-activating-factor (Kumar, R., Harvey, S.A.K., Kester, M., Hanahan, D.J. and Olson, M.S. (1988) Biochim. Biophys. Acta 963, 375-383). The present study demonstrates that this fluorocarbon perfusion technique maintains the integrity of the blood-brain barrier (BBB), as evidenced by the small volume (1.77-3.33%) accessible to [carboxyl-14C]inulin. 51-66% of the brain was accessible to 3H2O, except for the spinal cord which is poorly perfused (16% accessible to 3H2O). There is no effective perfusion of muscle tissue associated with the preparation (less than 6% accessible to 3H2O). Fast Fourier Transform analysis of digitized EEG data showed that in low frequency bands (less than 7.5 Hz) the IPRB had reduced electrical activity relative to the whole conscious animal. The GABA antagonist bicuculline, which has convulsant effects in vivo, causes a 3-4-fold increase in overall (root-mean-square) electrical activity, but decreases further the relative amplitude of low frequencies. With appropriate corrections, measurement of the oxygen consumption of the IPRB can be made without the necessity for venous cannulation. Oxygen consumption of the IPRB is flow-dependent. At a perfusion rate of 1.54 ml/min per g, unstimulated oxygen consumption of the IPRB is 2.07-2.23 mumol/min per g, or 67-72% of the consumption of the brain in vivo. Administration of bicuculline to the IPRB causes a 31% increase in lactate efflux, but only a 15% increase in oxygen uptake, suggesting that the preparation becomes functionally ischemic. Measurement of ATP/ADP levels in control and bicuculline-treated IPRBs confirms this. Other workers have used the IPRB as a model for the cerebral effects of pharmacological agents and of metabolic insult. The present study shows that under various experimental conditions oxygen uptake, analytical EEG measurements, and the integrity of the blood-brain barrier all can be monitored.

Nucleophilic attack of tert-butyl/phenylpyridines 3 on 1-chloro-2,4-dinitrobenzene 4 results in the formation of tert-butyl/phenyl substituted 2,4-dinitrophenylpyridinium chlorides 5. Benzoyl hydrazide and pyridyl acid hydrazides 6 were reacted with the pyridinium chlorides 5 furnishing the 2,4-dinitroanilino derivatives 7, which were subsequently hydrolyzed with water: p-dioxane to yield N-[pyridyl(phenyl)carbonylimino]-tert-butyl/phenylpyridinium ylides 8. The title compounds 9, N-[pyridyl(phenyl)carbonylamino]-tert-butyl/phenyl-1,2,3,6- tetrahydropyridines, were obtained by sodium borohydride reduction of the pyridinium ylides 8. The anti-inflammatory activities of compounds 9a-p were determined using the carrageenan-soaked sponge model of inflammation in Sprague Dawley rats. All compounds tested showed moderate to good anti-inflammatory effects compared to indomethacin. Compounds 9b, 9c and 9p were the most active analogs of the group in this model.

Reoxygenation of the hypoxic myocardium results in a number of processes, including an O2-dependent increase in total tissue Ca2+ and cell lysis in which mitochondrial electron transport plays a key role. In the present study we have isolated mitochondria from perfused rat hearts subjected to hypoxia and found no change in their respiratory function relative to controls. In contrast, mitochondria isolated immediately after reoxygenation of hypoxic-perfused hearts exhibited a specific and significant decrease in NADH:CoQ reductase (Complex I; EC 1.6.5.3) activity, as measured both polarographically and spectrophotometrically. Isolated cardiomyocytes subjected to a similar protocol of hypoxia/reoxygenation also exhibited a specific decrease in Complex I activity. Myocardial perfusion with media containing Ruthenium Red protected against the reoxygenation-dependent loss of Complex I activity. These observations taken together suggest that mitochondrial Ca2+ uptake on reoxygenation is implicated in the mechanism of the specific loss of Complex I activity.

Deletions of the mitochondrial genome were identified in 21 out of 58 patients (36 percent) with mitochondrial myopathies, 47 of whom had defects in the mitochondrial respiratory chain. In cases with Complex I defects, the deleted regions of mtDNA, were confined to structural genes encoding Complex I subunits but additionally involved the intervening tRNA genes and in one case included the large and small rRNA genes. In cases with more extensive loss of respiratory chain function, the deletions eliminated genes encoding subunits of Complexes I, IV and V, as well as several tRNAs. Complex I and Complex IV polypeptides were usually normal in deleted cases. This was in contrast to 7 out of 22 patients without detectable mtDNA deletions, who showed specific deficiencies of subunits encoded by nuclear genes. Further studies in one of these cases pointed to defective translocation of the Rieske precursor from the cytosol into the mitochondria. The genetic basis of the disease in 15 cases without detectable deletions or specific subunit deficiencies, remains unknown. The multiple biochemical abnormalities encountered in these cases would be consistent with more subtle alterations of the mitochondrial genome.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is thought to produce parkinsonism in humans and other primates through its inhibition of complex I. The recent discovery of mitochondrial complex I deficiency in the substantia nigra of patients with Parkinson's disease has provided a remarkable link between the idiopathic disease and the action of the neurotoxin MPTP. This article shows that complex I deficiency in Parkinson's disease is anatomically specific for the substantia nigra, and is not present in another neurodegenerative disorder involving the substantia nigra. Evidence is also provided to show that there is no correlation between L-3,4-dihydroxyphenylalanine therapy and complex I deficiency. These results suggest that complex I deficiency may be the underlying cause of dopaminergic cell death in Parkinson's disease.

A Navy helicopter pilot was found to have a suprasellar mass during evaluation for primary infertility and mildly elevated prolactin level. Extensive evaluation revealed no other abnormalities. After 1 year of followup without radiographic tumor enlargement, he was returned to flying duties with continuing medical monitoring. Aeromedical considerations for tumors in the juxtasellar region are reviewed, including neuroendocrine disorders, neuro-ophthalmologic defects, and neurological impairment. The impact of improved diagnostic capabilities on aeromedical disposition is discussed.

Injuries to the cervical region have been associated with high-G loads sustained during air combat maneuvering (ACM) in high performance fighter aircraft. The spectrum of injuries ranges from mild neck pain to musculoskeletal strain, injury to the nerve roots or spinal cord, and fracture of the cervical spine. A 36-year-old fighter pilot with 2,800 h in tactical jet aircraft developed progressive cervical dystonia (spasmodic torticollis), following an ACM flight. The patient was successfully treated with local intramuscular injections of botulinum toxin into the affected cervical muscles, resulting in total relief of his spasmodic torticollis. The aeromedical considerations of this rare complication of exposure to G forces in high performance aircraft are discussed.

Some of the different molecular pathologies of respiratory-chain dysfunction in human mitochondrial myopathies will be reviewed in relation to the findings in 58 cases. Deletions of mitochondrial DNA were identified in 21 cases [36%]. There was some correlation between the sites of the deletion and the mitochondrial biochemistry in patients with defects of Complex I but not in cases with more extensive loss of respiratory chain activity. Complex I and Complex IV polypeptides were usually normal in deleted cases. Non-deleted cases, however, often showed specific subunit deficiencies which involved the products of both nuclear and mitochondrial genes. Immunoblots of respiratory-chain polypeptides in one case pointed to defective translocation of the Rieske precursor from the cytosol into the mitochondria. The pathogenic role of circulating autoantibodies to specific matrix proteins and the nature of the target antigens in two patients with mitochondrial encephalomyopathies and respiratory-chain dysfunction will also be discussed.

L-Lactate (4-32 mM) added exogenously to resting or depolarised rat forebrain synaptosomes led to a significant decrease in intrasynaptosomal pH. Similarly depolarisation-induced increases in intrasynaptosomal calcium, calcium uptake, and acetylcholine release were all inhibited. These effects mimicked those previously observed in synaptosomes under anoxic conditions and suggest that lactate may be involved in limiting the damage due to calcium accumulation occurring during ischaemia. D-Lactate (added exogenously up to 32 mM) did not produce similar effects on these parameters even though the concentrations of intrasynaptosomal D-lactate reached levels comparable to those obtained with L-lactate (at 8-16 mM exogenous concentration). The results suggest that the mechanism of action of lactate on these parameters is stereospecific for the L-enantiomer. The effect of glucose availability on lactate production was assessed to explore the role of substrate availability on ischaemia/anoxic events. When exogenous glucose was increased (10-60 mM), there was no further increase in lactate production in normoxic synaptosomes, which suggests that glucose is not limiting under these conditions. When glucose was removed, as may occur in complete ischaemia, there was a significant decrease in lactate production after 60 min under anoxic or normoxic conditions. It would seem likely therefore that the mechanism underlying the changes observed in synaptosomes incubated under conditions reflecting complete ischaemia does not involve lactate.

Over the past 25 years, there have been an increasing number of fish tumor epizootics recognized in discrete geographical areas in North America. This is consistent with an association between tumor development in fish and exposure to waterborne contaminants as a result of increased industrialization. Reports of fish tumor epizootics from the literature, plus acquisitions at the Registry of Tumors in Lower Animals, Smithsonian Institution originate from 41 geographical regions in North America. Epizootics of hemic, neural, connective tissue, and gonial neoplasms seem unrelated to environmental pollution, but epizootics of hepatic and epidermal neoplasms appear to be caused or strongly influenced by environmental pollution. The 14 species with epizootic liver tumors are all bottom feeding fish, and tumor-bearing fish are generally located in areas where chemical contaminants are concentrated. Epidermal neoplasms are also found in fish near polluted areas, but a direct cause-and-effect link with chemical carcinogens is not clear.

A 15-yr-old boy with mitochondrial encephalomyopathy and NADH CoQ reductase (Complex I) deficiency is presented. Immunoblotting demonstrated specific deficiencies of the 24 kDa FeS protein of Complex I and subunit II of Complex IV. The patient's serum contained an antibody to a specific mitochondrial matrix polypeptide of apparent Mr 41 kDa. The specific polypeptide deficiencies involve products of nuclear (24 kDa FeS protein) and mitochondrial (subunit II) genes and suggest some intergenomic regulation. The relevance of the circulating antibody to the pathogenesis of the patient's Complex I deficiency is discussed.

The structure and function of mitochondrial respiratory-chain enzyme proteins were studied postmortem in the substantia nigra of nine patients with Parkinson's disease and nine matched controls. Total protein and mitochondrial mass were similar in the two groups. NADH-ubiquinone reductase (Complex I) and NADH cytochrome c reductase activities were significantly reduced, whereas succinate cytochrome c reductase activity was normal. These results indicated a specific defect of Complex I activity in the substantia nigra of patients with Parkinson's disease. This biochemical defect is the same as that produced in animal models of parkinsonism by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and adds further support to the proposition that Parkinson's disease may be due to an environmental toxin with action(s) similar to those of MPTP.

This article reviews the available medical data that form the basis for the U.S. Navy's policy on aeromedical disposition of Human Immunodeficiency Virus (HIV) seropositive flyers. Following a brief review of military HIV antibody testing and clinical evaluation, this article addresses the main issue in the Navy's aeromedical disposition policy--the subtle neurologic sequelae of HIV infection or HIV encephalopathy. Following a review of the available knowledge of HIV involvement in the nervous system, the aeromedical considerations that form the basis of Navy policy of permanently grounding without waiver all HIV seropositive flyers is discussed.

A series of Clostridium perfringens-related gastrointestinal outbreaks occurred over a period of several months among elderly, chronic care patients in a psychiatric hospital. Several serotypes of C. perfringens and many nontypeable isolates were found. The distribution of certain serotypes and the incidence of detection of enterotoxin in fecal extracts were related to wards on which patients were resident (six wards were involved). Several patients were reported to have chronic or recurring fecal incontinence or diarrhea or both. With a background of elevated spore counts of several serotypes and chronic diarrhea, only detection of enterotoxin could provide definitive evidence of C. perfringens etiology in gastoenteritis cases.

1. Data are provided that indicate that the rat brain acetoacetyl-CoA deacylase is almost exclusively mitochondrial. Developmental studies show that this enzyme more than doubles its activity during suckling (0--21 days) and then maintains this activity in adults (approx. 1.1 units/g wet wt.). 2. Kinetic studies (on the acetoacetyl-CoA deacylase) in a purified brain mitochondrial preparation give a Vmax. of 47 nmol/min per mg of protein, and a Km for acetoacetyl-CoA of 5.2 micron and are compatible with substrate inhibition by acetoacetyl-CoA above concentrations of 47 micron. 3. The total brain 3-hydroxy-3-methyl-glutaryl-CoA synthase remains constant in the developing and adult rat brain (approx. 1.2 units/g wet wt.). This enzyme is located in both the mitochondrial and cytosolic fractions. During suckling (0--21 days) the mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase represents approx. one-third of the total, but this increases markedly to about 60% of the total in the adult. The cytosolic enzyme correspondingly falls to approx. 40% of the total. 4. The role of the acetoacetyl-CoA deacylase in providing cytosolic acetoacetate for biosynthetic activities in the developing brain is discussed.

Organ cultures of human and guinea-pig genital mucosa were inoculated with Neisseria gonorrhoeae, and the association of the bacteria with the epithelial surface of each tissue was studied by light microscopy and by scanning electron microscopy. Gonococci attached to the mucosa of human fallopian tube, adhering specifically to the surface of non-ciliated epithelial cells. In contrast, gonococci rarely attached to the mucosal surface of guinea-pig uterine horn, vagina or bladder, although organisms were occasionally seen associated with the submucosal tissue in areas where the epithelium had sloughed, and in extracellular mucus secretions. There is no evidence from this study that gonococci adhere to guinea-pig tissue in a manner analogous to that seen with human genital tissue.

Synaptosomes from several regions of the rat brain were found to exhibit half-maximal rates of 14CO2 output and [14C]acetylcholine synthesis from D-[U-14C]glucose at glucose concentrations approx. 50-fold lower than those required by the brain in situ. However, synaptosomal acetylcholine synthesis was found not to be directly proportional to substrate oxidation as measured by 14CO2 output. When synaptosomes had been exposed to anoxia in vitro, their metabolic indices (14CO2 and [14C]acetylcholine synthesis, and adenine nucleotide levels) were found not to be significantly different from control aerobic values, unless they had been subjected to veratridine depolarization. This is in accord with previous findings that neither the absolute metabolic rates nor the vulnerability to hypoxic damage exhibited by brain in situ is reflected by brain slices in vitro, unless these are stimulated by depolarization. The use of synaptosomes as a model for synaptic damage in vivo is discussed.