Rapid cold hardening delays the onset of anoxia-induced coma via an octopaminergic pathway in Locusta migratoria

Rapid cold hardening (RCH) is a short-term hormesis that occurs in many invertebrate species, especially in insects. Although RCH is best known as enhancing cold tolerance, it can also enhance anoxic tolerance. When exposed to prolonged anoxia, insects enter a reversible coma, which is associated with spreading depolarization (SD) in the central nervous system (CNS). In this study, we investigated the effects of RCH and octopamine (OA) on anoxia-induced SD in L. migratoria. OA is an insect stress hormone that has roles in many physiological processes. Thus, we hypothesized that OA is involved in the mechanism of RCH. First, we found that RCH affects the K⁺ sensitivity of the locust blood brain barrier (BBB) in a way similar to the previously described effects of OA. Next, using SD as an indicator of anoxia-induced coma, we took a pharmacological approach to investigate the effects of OA and epinastine (EP), an octopaminergic receptor (OctR) antagonist. We found that OA mimics, whereas EP blocks, the effect of RCH on anoxia-induced SD. This study demonstrates that OA is involved in the mechanism of RCH in delaying the onset of anoxia-induced locust coma and contributes to determining the mechanism of RCH that modulates insect stress tolerances.

Immediate and Long-Term Outcome of Acute H2S Intoxication Induced Coma in Unanesthetized Rats: Effects of Methylene Blue

BACKGROUND

Acute hydrogen sulfide (H2S) poisoning produces a coma, the outcome of which ranges from full recovery to severe neurological deficits. The aim of our study was to 1--describe the immediate and long-term neurological effects following H2S-induced coma in un-anesthetized rats, and 2--determine the potential benefit of methylene blue (MB), a compound we previously found to counteract acute sulfide cardiac toxicity.

METHODS

NaHS was administered IP in un-sedated rats to produce a coma (n = 34). One minute into coma, the rats received MB (4 mg/kg i.v.) or saline. The surviving rats were followed clinically and assigned to Morris water maze (MWM) and open field testing then sacrificed at day 7.

RESULTS

Sixty percent of the non-treated comatose rats died by pulseless electrical activity. Nine percent recovered with neurological deficits requiring euthanasia, their brain examination revealed major neuronal necrosis of the superficial and middle layers of the cerebral cortex and the posterior thalamus, with variable necrosis of the caudate putamen, but no lesions of the hippocampus or the cerebellum, in contrast to the typical distribution of post-ischemic lesions. The remaining animals displayed, on average, a significantly less effective search strategy than the control rats (n = 21) during MWM testing. Meanwhile, 75% of rats that received MB survived and could perform the MWM test (P<0.05 vs non-treated animals). The treated animals displayed a significantly higher occurrence of spatial search than the non-treated animals. However, a similar proportion of cortical necrosis was observed in both groups, with a milder clinical presentation following MB.

CONCLUSION

In conclusion, in rats surviving H2S induced coma, spatial search patterns were used less frequently than in control animals. A small percentage of rats presented necrotic neuronal lesions, which distribution differed from post-ischemic lesions. MB dramatically improved the immediate survival and spatial search strategy in the surviving rats.

Effects of Alda-1, an Aldehyde Dehydrogenase-2 Agonist, on Hypoglycemic Neuronal Death

Hypoglycemic encephalopathy (HE) is caused by a lack of glucose availability to neuronal cells, and no neuroprotective drugs have been developed as yet. Studies on the pathogenesis of HE and the development of new neuroprotective drugs have been conducted using animal models such as the hypoglycemic coma model and non-coma hypoglycemia model. However, both models have inherent problems, and establishment of animal models that mimic clinical situations is desirable. In this study, we first developed a short-term hypoglycemic coma model in which rats could be maintained in an isoelectric electroencephalogram (EEG) state for 2 min and subsequent hyperglycemia without requiring anti-seizure drugs and an artificial ventilation. This condition caused the production of 4-hydroxy-2-nonenal (4-HNE), a cytotoxic aldehyde, in neurons of the hippocampus and cerebral cortex, and a marked increase in neuronal death as evaluated by Fluoro-Jade B (FJB) staining. We also investigated whether N-(1,3-benzodioxole-5-ylmethyl)-2,6-dichlorobenzamide (Alda-1), a small-molecule agonist of aldehyde dehydrogenase-2, could attenuate 4-HNE levels and reduce hypoglycemic neuronal death. After confirming that EEG recordings remained isoelectric for 2 min, Alda-1 (8.5 mg/kg) or vehicle (dimethyl sulfoxide; DMSO) was administered intravenously with glucose to maintain a blood glucose level of 250 to 270 mg/dL. Fewer 4-HNE and FJB-positive cells were observed in the cerebral cortex of Alda-1-treated rats than in DMSO-treated rats 24 h after glucose administration (P = 0.002 and P = 0.020). Thus, activation of the ALDH2 pathway could be a molecular target for HE treatment, and Alda-1 is a potentially neuroprotective agent that exerts a beneficial effect on neurons when intravenously administered simultaneously with glucose.

Axonal pathology in traumatic brain injury

Over the past 70years, diffuse axonal injury (DAI) has emerged as one of the most common and important pathological features of traumatic brain injury (TBI). Axons in the white matter appear to be especially vulnerable to injury due to the mechanical loading of the brain during TBI. As such, DAI has been found in all severities of TBI and may represent a key pathologic substrate of mild TBI (concussion). Pathologically, DAI encompasses a spectrum of abnormalities from primary mechanical breaking of the axonal cytoskeleton, to transport interruption, swelling and proteolysis, through secondary physiological changes. Depending on the severity and extent of injury, these changes can manifest acutely as immediate loss of consciousness or confusion and persist as coma and/or cognitive dysfunction. In addition, recent evidence suggests that TBI may induce long-term neurodegenerative processes, such as insidiously progressive axonal pathology. Indeed, axonal degeneration has been found to continue even years after injury in humans, and appears to play a role in the development of Alzheimer's disease-like pathological changes. Here we review the current understanding of DAI as a uniquely mechanical injury, its histopathological identification, and its acute and chronic pathogenesis following TBI.

Cold hardening modulates K+ homeostasis in the brain of Drosophila melanogaster during chill coma

Environmental temperature is one of the most important abiotic factors affecting insect behaviour; virtually all physiological processes, including those which regulate nervous system function, are affected. At both low and high temperature extremes insects enter a coma during which individuals do not display behaviour and are unresponsive to stimulation. We investigated neurophysiological correlates of chill and hyperthermic coma in Drosophila melanogaster. Coma resulting from anoxia causes a profound loss of K(+) homeostasis characterized by a surge in extracellular K(+) concentration ([K(+)](o)) in the brain. We recorded [K(+)](o) in the brain during exposure to both low and high temperatures and observed a similar surge in [K(+)](o) which recovered to baseline concentrations following return to room temperature. We also found that rapid cold hardening (RCH) using a cold pretreatment (4°C for 2h; 2h recovery at room temperature) increased the peak brain [K(+)](o) reached during a subsequent chill coma and increased the rates of accumulation and clearance of [K(+)](o). We conclude that RCH preserves K(+) homeostasis in the fly brain during exposure to cold by reducing the temperature sensitivity of the rates of homeostatic processes.

Isolated ACTH deficiency presenting with a glucocorticoid-responsive triphasic wave coma

We report the case of a 58-year-old woman who presented with acutely developed coma characterized by electroencephalographic triphasic waves (TWs) in the absence of metabolic derangement. The patient's coma and TWs were promptly resolved after the administration of glucocorticoids, and thereafter isolated ACTH deficiency was diagnosed. Isolated ACTH deficiency may present with glucocorticoid-responsive acute encephalopathy without hypoglycemia, hyponatremia, or systemic hypotension. Electroencephalographic TWs or bursts of slow waves may be a clue to the diagnosis of this rare condition in patients with coma of unknown origin.

Glial Hsp70 protects K+ homeostasis in the Drosophila brain during repetitive anoxic depolarization

Neural tissue is particularly vulnerable to metabolic stress and loss of ion homeostasis. Repetitive stress generally leads to more permanent dysfunction but the mechanisms underlying this progression are poorly understood. We investigated the effects of energetic compromise in Drosophila by targeting the Na(+)/K(+)-ATPase. Acute ouabain treatment of intact flies resulted in subsequent repetitive comas that led to death and were associated with transient loss of K(+) homeostasis in the brain. Heat shock pre-conditioned flies were resistant to ouabain treatment. To control the timing of repeated loss of ion homeostasis we subjected flies to repetitive anoxia while recording extracellular [K(+)] in the brain. We show that targeted expression of the chaperone protein Hsp70 in glial cells delays a permanent loss of ion homeostasis associated with repetitive anoxic stress and suggest that this is a useful model for investigating molecular mechanisms of neuroprotection.

Metabolic and neurologic sequelae in a patient with long-standing anorexia nervosa who presented with septic shock and deep hypoglycemia

OBJECTIVE

To report the case of a 48-year female with chronic remitting anorexia nervosa who was found comatose at home and admitted to our hospital with a deep hypoglycemia (glucose level 0.6 mmol/L; 11 mg/dL) and septic shock secondary to a bilateral pneumonia.

METHOD

Case report.

RESULTS

After admission to the critical care unit, she further displayed a number of pronounced complications known to be associated with anorexia, including hypophosphatemia, disturbed liver functions and depression of all three hematological cell lines. The neurological recovery of the patient was complicated by encephalopathy and transient tetraparesis. With initial deep hypoglycemia at presentation and persisting coma, magnetic resonance imaging performed 5 days later did not demonstrate characteristic post-hypoglycemic abnormalities. Neuroradiological examination did however reveal the presence of extensive calcifications in the basal ganglia known as Fahr's syndrome.

DISCUSSION

The potential relation between anorexia nervosa and Fahr syndrome has not been described before. The fact that this patient survived a glucose level that is usually associated with a very poor outcome is probably related to its special origin.

[Thalamic metabolism and neurological outcome after traumatic brain injury. A voxel-based morphometric FDG-PET study]

OBJECTIVE

to study the relationship between thalamic metabolism and neurological outcome in patients who had sustained a traumatic brain injury (TBI).

METHODS

nineteen patients who had sustained a severe TBI and ten control subjects were included in this study. Six of the 19 patients had a low level of consciousness (vegetative state or minimally conscious state), while thirteen showed normal consciousness. All patients underwent a PET with 18F-FDG, 459.4 +/- 470.9 days after the TBI. The FDG-PET images were normalized in intensity, with a metabolic template being created from data derived from all subjects. The thalamic trace was generated automatically with a mask of the region of interest in order to evaluate its metabolism. A comparison between the two groups was carried out by a two sample voxel-based T-test, under the General Linear Model (GLM) framework.

RESULTS

patients with low consciousness had lower thalamic metabolism (MNI-Talairach coordinates: 12, -24, 18; T = 4.1) than patients with adequate awareness (14, -28, 6; T = 5.5). Control subjects showed the greatest thalamic metabolism compared to both patients groups. These differences in metabolism were more pronounced in the internal regions of the thalamus.

CONCLUSIONS

the applied method may be a useful ancillary tool to assess neurological outcomes after a TBI, since it permits an objective quantitative assessment of metabolic function for groups of subjects. Our results confirm the vulnerability of the thalamus to suffering the effects of the acceleration-deceleration forces generated during a TBI. It is hypothesized that patients with low thalamic metabolism represent a subset of subjects highly vulnerable to neurological and functional disability after TBI.

Brain interstitial fluid TNF-alpha after subarachnoid hemorrhage

OBJECTIVE

TNF-alpha is an inflammatory cytokine that plays a central role in promoting the cascade of events leading to an inflammatory response. Recent studies have suggested that TNF-alpha may play a key role in the formation and rupture of cerebral aneurysms, and that the underlying cerebral inflammatory response is a major determinate of outcome following subrarachnoid hemorrhage (SAH).

METHODS

We studied 14 comatose SAH patients who underwent multimodality neuromonitoring with intracranial pressure (ICP) and cerebral microdialysis as part of their clinical care. Continuous physiological variables were time-locked every 8h and recorded at the same point that brain interstitial fluid TNF-alpha was measured in brain microdialysis samples. Significant associations were determined using generalized estimation equations.

RESULTS

Each patient had a mean of 9 brain tissue TNF-alpha measurements obtained over an average of 72h of monitoring. TNF-alpha levels rose progressively over time. Predictors of elevated brain interstitial TNF-alpha included higher brain interstitial fluid glucose levels (beta=0.066, p<0.02), intraventricular hemorrhage (beta=0.085, p<0.021), and aneurysm size >6mm (beta=0.14, p<0.001). There was no relationship between TNF-alpha levels and the burden of cisternal SAH; concurrent measurements of serum glucose, or lactate-pyruvate ratio.

INTERPRETATION

Brain interstitial TNF-alpha levels are elevated after SAH, and are associated with large aneurysm size, the burden of intraventricular blood, and elevation brain interstitial glucose levels.

[Vegetative state (prolonged coma) as manifestation of stable pathological state]

Complex examination of 25 patients in vegetative state was performed before and after correction of secondary brain damage. Catamnesis over a period of at least 6 months was traced. Preliminary results showed that better recovery of consciousness and cognitive functions was observed if before treatment diffuse glucose hypometabolism was significantly more widespread than morphological changes. Minimal positive dynamics was detected in cases in which the reduction of glucose metabolism was minimal. This and other paradoxical results become explainable if to consider vegetative state as stable pathological state of the brain. This open new approaches to treatment of this group of patients.

Life-threatening dextromethorphan intoxication associated with interaction with amitriptyline in a poor CYP2D6 metabolizer: a single case re-exposure study

We report a case of life-threatening intoxication and a controlled re-exposure study to dextromethorphan. A 60-year-old man developed postsurgical neuropathic cervical pain treated by hydromorphone, gabapentin, clonazepam, and amitriptyline. He received a dextromethorphan preparation for a catarrhal syndrome. Two days later, he was admitted into an emergency department in a profound coma. Thirty-six hours later, after withdrawal of all drugs, the situation normalized. A genotyping for UDP-glucuronyltransferase 1A1 and CYP2D6 was followed by a re-exposure study. During the three days, vital parameters and side effects of drugs were prospectively recorded. The second day, dextromethorphan was introduced. No significant impairment in parameters nor influence on analgesic efficacy were noted. Dextromethorphan concentrations suggested an accumulation without reaching any steady state. Somnolence was noted for plasma concentrations around 100ng/mL. The CYP2D6*4 variant leading to a poor metabolizer phenotype was found. Moreover, this phenotype was potentially aggravated by amitriptyline intake. This study allowed the identification and the confirmation of the cause of the coma. In conclusion, it is probably wise to recommend avoiding dextromethorphan in patients taking tricyclic antidepressants or another inhibitor of CYP2D6. Drug-drug interactions are probably underdiagnosed and underreported, and drugs considered as safe may induce serious complications.

[Use of amantadine sulfate (PK-MERZ) during emergence from coma: results of a multicenter study]

The paper gives the results of the first multicenter study of the efficiency of using amantadine sulfate (PK-Merz) in patients with acute cerebral disease during coma emergence. The study has shown a positive effect of this drug at coma emergence, which manifested itself as clinical improvement and a better outcome of the disease. Full objectivism of the findings requires further studies.

[Coma: etiology, diagnosis, and treatment]

Coma is the disorder of consciousness because of the damage to diffused bilateral cerebral hemisphere cortex or reticular activating system. Coma can be caused by neurogenic (head brain injury), metabolic (endogenic), and toxic (exogenic) factors. To determine the cause of metabolic and toxic coma, laboratory tests are performed; in case of neurogenic coma, the neurologic examination is essential, when five systems are evaluated: the level of consciousness (according to Glasgow Coma Scale or Full Outline of Unresponsiveness Scale), photoreaction of pupils and ophthalmoscopic examination, oculomotoric, motoric, and cardiopulmonary systems. For the treatment of coma, adequate oxygenation and correction of blood circulation disorders are important. The treatment of metabolic coma is guided by special schemes; antidotes often are needed in the treatment of toxic coma, and surgery helps if traumatic brain injury is present. The prognosis and outcomes of the comatose patient depend on the age and comorbid diseases of the patient, the underlying cause of coma, timely medical help and its quality, and intensive treatment and care of the patient in coma.

Magnetic resonance spectroscopy in adult-onset citrullinemia: elevated glutamine levels in comatose patients

BACKGROUND

Adult-onset type II citrullinemia is an inborn error of urea cycle metabolism that can lead to hyperammonemic encephalopathy and coma. However, type II citrullinemia is rare outside Japan, and diagnosis and treatment can be delayed. Magnetic resonance spectroscopy may be a useful adjunct to magnetic resonance imaging, and has been applied to noninvasively study chemical metabolism in the human brain.

PATIENTS

We describe 2 patients with type II citrullinemia who presented with episodic postprandial somnolence and coma. Diffusion-weighted magnetic resonance imaging showed bilaterally symmetrical signal abnormalities of the insular cortex and cingulate gyrus. On magnetic resonance spectroscopy, glutamine and glutamate levels were elevated, and choline and myo-inositol levels were decreased. The diagnosis of citrullinemia was confirmed based on elevated plasma ammonia and citrulline levels.

CONCLUSION

Characteristic features found at the time of magnetic resonance imaging and magnetic resonance spectroscopy may be helpful for early diagnosis of type II citrullinemia in adult patients who present with hyperammonemic encephalopathy and coma.

[The beginnings of modern biological psychiatry in Hungary: the atropine coma. A historical overview]

In the authors' opinion modern biological psychiatry in Hungary started with the investigations into the biological mechanism of atropine coma therapy. Atropine coma was used in the period between 1950 and 1975 mainly in the treatment of various psychoses and obsessive compulsive disorder. In a previous communication the method, indications and adverse effects of atropine coma were outlined and the professional and broader social reasons for its eventual disappearance were discussed. In this paper the therapeutic effectiveness and research into the biological mode of action of atropine coma are summarized. Although thousands of patients received atropine coma therapy in the United States and in several Central-Eastern European countries including Hungary, this therapeutic modality is hardly ever features even in papers on the history of psychiatry. This is all the more surprising because initial therapeutic results with atropine coma were favourable and it seemed to be a more safe and efficient treatment than the more widely used insulin coma.

[Hyperammonemia type II as an example of urea cycle disorder]

Ornithine transcarbamylase deficiency is the most common inherited urea cycle disorder. Its clinical manifestations as lethargy, vomites, coma and cerebral edema are the effect of the higher concentration of the ammonia in plasma. Hyperammonemia, caused by mutation in ornithine transcarbamylase gene, is often considered as a reason of coma by pediatricians but skipped by internist, although it is the third reason of hepatic coma in adults. This article is the recapitulation of published studies and their implication on everyday clinical practice.

Endozepines in recurrent stupor

Stupor is a condition from which the subject can be aroused only by vigorous stimuli. Most patients with stupor have a diffuse organic cerebral dysfunction. Rarely stupor is recurrent and no specific causes can be found. Patients with idiopathic recurrent stupor were awakened by i.v. administration of an antagonist (flumazenil) of the benzodiazepine recognition site located in the GABA(A) receptor. Since no exogenous benzodiazepines were detected in plasma and cerebrospinal fluid by high performance liquid chromatography, an excess of endogenous benzodiazepine-like compounds (endozepines) was proposed as the cause of stupor. The existence of endozepines, their widespread distribution in the CNS and their involvement in hepatic encephalopathy are established. However, the origin of these compounds, how biosynthesis occurs and the mechanisms and causes through which they alter brain functions are poorly understood. The fact that a number of synthetic benzodiazepines are difficult to detect using conventional techniques and the discovery that some cases of recurrent stupor were caused by fraudulent administration of lorazepam question whether the concept of endozepine recurrent stupor can be sustained. This review summarizes the state of endozepine physiology and pharmacology and the clinical syndromes attributed to their involvement. A diagnostic work-up to define endozepine-induced recurrent stupor is suggested.

Proton MR spectroscopy detected glutamate/glutamine is increased in children with traumatic brain injury

Adults with traumatic brain injury (TBI) have been shown by invasive methods to have increased levels of the excitatory neurotransmitter glutamate. It is unclear whether glutamate release contributes to primary or secondary injury and whether its protracted elevation is predictive of a poor outcome. Preliminary studies at our institution in adults found that early increases in magnetic resonance spectroscopy (MRS)-detected glutamate/glutamine (Glx) were associated with poor outcomes. We therefore studied 38 children (mean age, 11 years; range, 1.6-17 years) who had TBI with quantitative short-echo time (STEAM, TE = 20 msec) proton MRS, a mean of 7 +/- 4 (range, 1-17) days after injury in order to determine if their occipital or parietal Glx levels correlated with the severity of injury or outcome. Occipital Glx was significantly increased in children with TBI compared to controls (13.5 +/- 2.4 vs. 10.7 +/- 1.8; p = 0.002), but there was no difference between children with good compared to poor outcomes as determined by the Pediatric Cerebral Performance Category Scale score at 6-12 months after injury. We also did not find a correlation between the amount of Glx and the initial Glasgow Coma Scale score, duration of coma, nor with changes in spectral metabolites, including N-acetyl aspartate, choline, and myoinositol. In part, this may have occurred because, in this study, most patients with poor outcomes were studied later than patients with good outcomes, potentially beyond the time frame for peak elevation of Glx after injury. Additional early and late studies of patients with varying degrees of injury are required to assess the importance to the pathophysiology of TBI of this excitatory neurotransmitter.

Metabolic Correction of Gas Exchange Disturbances in Rats with Barbiturate Coma

Krebs cycle intermediates normalized gas exchange and decreased the mortality rate in rats with barbiturate coma. Treatment with other substrates including glucose and products of glycolysis was ineffective. Oxygen inhalation had no effect on oxygen consumption and indexes of external respiration. Our results suggest that deficiency of endogenous intermediates of the Krebs cycle, but not disturbances in oxygen mass transfer, serves as a limiting factor for oxygen consumption in rats with barbiturate coma.

Mitochondrial DNA deletion in a child with megaloblastic anemia and recurrent encephalopathy

A 3 1/2-year-old boy presented with megaloblastic anemia and recurrent episodes of severe lactic acidosis and coma. At age 4 years, he developed sepsis and died; postmortem examination failed to show any gross abnormality in any tissue. Biochemical analysis of muscle showed decreased activities for all respiratory chain enzymes except complex II. Muscle histochemistry revealed diffuse cytochrome c oxidase deficiency. Southern blot analysis of mitochondrial DNA from muscle, liver, and blood showed a heteroplasmic single mitochindrial DNA deletion of 2.4 kb, which removed the genes for cytochrome c oxidase I and II and the transfer ribonucleic acid genes for serine and aspartic acid. Single large-scale deletions in mitochondrial DNA have been associated with Pearson's syndrome, Kearns-Sayre syndrome, and progressive external ophthalmoplegia. This patient's presentation is unusual and suggests an overlap between Pearson's syndrome and Kearns-Sayre syndrome.

[Method of pharmacological treatment of the consequences of hypoxia in critically ill patients with acute poisoning]

The multi-factor effect of pharmacological preparations reamberine and citotoflavine, which contain succinate, in critical conditions is preconditioned by the impact they produce on a total energy deficit caused by a long-term hypoxia. The correction of energy deficit improves the therapy of patients in coma, which resulted from poisonings by neurotropic substances. The therapeutic effect manifested itself through a shorter state of coma from 25 to 12.5%. However, an analysis of died patients, who received the metabolic antihypoxants, showed that these drugs are not effective, when the time lapse from poisoning to medical aid exceeded 20 hours. When perftoran, a corrector of oxygen transport, and antihypoxant cytoflavin were added to the therapy scheme, it resulted in that 22 of 24 patients, who were also taken to clinic in the state of coma after 20 and more hours, survived, while all patients in the comparison group (20 patients) died despite an intensive therapy.

[Recurrent idiopathic stupor in a patient: responsibility of exogenous or endogenous benzodiazepines?]

Recurrent transitory consciousness loss represents a neurological diagnostic difficulty. A 56 year old man was hospitalised for recurrent stupor episodes. Explorations allowed to exclude hepatic, renal or respiratory failures, epilepsy or sleep disorder. During a stuporous state, since the patient was clearly awakened by flumazenil administration, the retained diagnosis was idiopathic recurrent stupor, a rare and not well-known disease. The authors discuss the possible effect of a treatment with zolpidem, though its pharmacokinetic characteristics did not correspond to the patient manifestations, and the possible responsibility of endogenous benzodiazepines in the genesis of this trouble.

Systematic review of prediction of poor outcome in anoxic-ischaemic coma with biochemical markers of brain damage

OBJECTIVE

To investigate whether accurate prognostic rules can be derived from the combined results of studies concerning prediction of poor prognosis in anoxic-ischaemic coma with biochemical markers of brain damage in cerebrospinal fluid (CSF) or serum.

DESIGN

A meta-analysis of prognostic studies in anoxic-ischaemic coma, selected from Medline and EMBASE databases, according to predefined criteria.

SUBJECTS

Twenty-eight studies, with a total of 802 unselected, consecutive patients, in which tests, sampling time and outcome measures were described unequivocally and results were described using clear cut-off values or raw data.

MAIN OUTCOME MEASURES

Poor outcome, defined as death or vegetative state, versus good outcome, defined as any other outcome state.

ANALYSES

The overall prognostic accuracy of these variables was expressed as the 95% CIs of the pooled false-positive test rate and the pooled positive-likelihood ratios.

RESULTS

Only markers in CSF (creatine kinase isoenzyme (CKBB) >204 U/l, neuron specific enolase (NSE) >33 ng/ml, lactate dehydrogenase (LDH) >82 U/l and glutamate oxaloacetate (GOT) >62 U/l) reached a 0% false-positive rate. However, due to small sample sizes, the confidence limits were wide. The accuracy of prediction of poor outcome seemed acceptably high for CSF-CKBB (pooled false-positive rate 0% [95% CI 0-2.3%]; pooled positive-likelihood ratio 33.2 [95% CI 4.8-230.2]), but this result was based on two retrospective studies without blinding of the treating physicians for the test result.

CONCLUSIONS

Because of small numbers of patients studied and methodological limitations the combined results are not sufficiently accurate to provide a solid basis for non-treatment decisions.

Protein ubiquitination in rat brain following hypoglycemic coma

Hypoglycemic coma of 30 min duration selectively damages CA1 pyramidal neurons and the crest of dentate gyrus (DG) granule cells in hippocampus. Here, we show by high-resolution confocal microscopy and biochemical analysis that 30 min of hypoglycemic coma induces the ubiquitination and aggregation of several proteins in rat brain tissues. Protein ubiquitination and aggregation occurred in the CA1 and DG regions as early as the end of 30 min of hypoglycemic coma and lasted until neuronal death in the late recovery period after hypoglycemia. In comparison, the neurons surviving hypoglycemia were less affected. On western blots, ubiquitinated proteins (ubi-proteins) were present mainly in Triton-insoluble pellets, indicating that they are irreversibly aggregated. We conclude that proteins are ubiquitinated and aggregated in neurons after hypoglycemia prior to their death. We hypothesize that protein ubiquitination and aggregation may contribute to neuronal damage after hypoglycemia.

[Lipid peroxidation and its connection with the change in composition and antioxidant properties of lipids in comatogenic forms of acute viral hepatitis B]

81 patients of acute viral hepatitis B (AVHB) without symptoms of acute hepatic encephalopathy, 39 AVHB patients with such symptoms and 115 age and sex match healthy controls were biochemically and clinically investigated. Besides usual biochemical analyses, some special parameters such as interrelationship between the patterns of lipid peroxidation (LPO) (conjugated dienes and ketodienes and the lipid antioxidant activity) and alterations in lipid composition (content of total lipids, phospholipids and cholesterol) were studied in blood serum. Concentration of LPO products in patients with mild, moderate and severe AVHB without symptoms of encephalopathy was found to be significantly lower than in controls. Relative content of phospholipids in the total lipid fraction as well as antioxidant activity of lipids were elevated, while relative content of cholesterol and level of lipid oxidation were lowered. Increasing of antioxidant activity and decreasing of LPO products coincides with the severity of disease. Intensification of LPO occurs only in patients with symptoms of acute hepatic encephalopathy (in coma and precoma). High levels of LPO products and low levels of total phospholipids in blood serum were found in these patients. The persistence of a high level of peroxides in AVHB suggests the existence of severe, irreversible lesions. Among the patients a risk for the development of severe outcome was found. We suppose that the parameters of oxidative stress may be useful as early prognostic factor and that antioxidants may be a useful for the optimal therapy of comatogenous state of AVHB.

Alteration of cyclic adenosine monophosphate response element binding protein in rat brain after hypoglycemic coma

In the current study, the temporal and regional changes of the transcription factor cyclic adenosine monophosphate response element binding protein (CREB) were investigated in rat brains subjected to 30 minutes of hypoglycemic coma followed by varied periods of recovery using Western blot and confocal microscopy. The total amount of CREB was not altered in any area examined after coma. The level of the phosphorylated form of CREB decreased during coma but rebounded after recovery. In the relatively resistant areas, such as the inner layers of the neocortex and the inner and outer blades of the dentate gyms (DG), phospho-CREB increased greater than the control level after 30 minutes of recovery and continued to increase up to 3 hours of recovery. In contrast, little or no increase of phospho-CREB was observed during the recovery period in the outer layers of the neocortex and at the tip of the DG, that is, regions that are selectively vulnerable to hypoglycemic insults. The current findings suggest that a neuroprotective signaling pathway may be more activated in the resistant regions than in the vulnerable ones after hypoglycemic coma.

Evidence that kynurenine pathway metabolites mediate hyperbaric oxygen-induced convulsions

Metabolism of tryptophan (TRP) through the kynurenine (KYN) pathway in brain, liver, and kidney produces intermediates including the neuroactive agonist quinolinic acid (QA) and the antagonists kynurenic acid (KA) and anthranilic acid (AA) for N-methyl D-aspartate (NMDA) receptors in the central nervous system. We hypothesized that elevated concentrations of QA, KA, or AA can moderate the convulsions that are observed during exposure of rats to hyperbaric oxygen (HBO). We found that i.p. administration of TRP or KYN (both of which cross the blood-brain barrier) had no effect on HBO-induced seizures. However, AA (administered i.p.) or gavage administration of the KYN pathway blocking drug Ro 61-8048, both of which enter the brain from the circulatory system, affect the time to first convulsion and/or coma during HBO in a manner consistent with a modulatory role for seizure activity.

Differential phosphorylation at Ser473 and Thr308 of Akt-1 in rat brain following hypoglycemic coma

We analyzed both total Akt-1 and phosphorylation of Akt-1 at residues Ser473 and Thr308 (phospho-Akt-1(Ser474) and phospho-Akt-1(Thr308), respectively) in the outer and inner layers of cortex following 30 min of hypoglycemic coma by Western blot analyses and confocal microscopy. The total amount of Akt-1 was not altered in any area examined. Phospho-Akt-1(Ser474), however, increased significantly in both layers of cortex at 0 and 30 min of recovery, but returned to control level at 3 h of recovery. In the vulnerable area (outer layer of cortex), no upregulation of phospho-Akt-1(Thr308) was observed at any time points examined. In the resistant area like inner layer of cortex, however, phospho-Akt-1(Thr308) was significantly over the control level at 3 h of recovery. Confocal microscopy result indicates that most of phospho-Akt-1(Thr308) had already moved into nucleus at 3 h of recovery. Our results suggest that Akt-1, when phosphorylated at Thr308, may play a protective role for neurons in the resistant regions of the brain.

Myxedema coma of both primary and secondary origin, with non-classic presentation and extremely elevated creatine kinase

Myxedema coma is a rare, often fatal endocrine emergency that concerns elderly patients with long-standing primary hypothyroidism; myxedema coma of central origin is exceedingly rare. Here, we report a 37-year-old woman in whom classical symptoms of hypothyroidism had been absent. Six years earlier, she had severe obstetric hemorrhage and, shortly after, two subsequent episodes of pericardial effusion. On the day of admission, pericardiocentesis was performed for the third episode of pericardial effusion. Because of the subsequent grave arrhythmias and unconsciousness, she was transferred to our ICU. Prior to the endocrine consultation, a silent myocardial infarction had been suspected, based on the extremely high serum levels of creatine kinase (CK) and isoenzyme CK-MB. However, based on thyroid sonography, pituitary computed tomography, elevated titers of antithyroid antibodies and pituitary stimulation tests, the final diagnosis was myxedema coma of dual origin: an atrophic variant of Hashimoto's thyroiditis and post-necrotic pituitary atrophy (Sheehan syndrome). Substitutive therapy caused a prompt clinical amelioration and normalization of CK levels. Our patient is the first case of myxedema coma of double etiology, and illustrates how its presentation deviates markedly from the one endocrinologists and physicians at ICU are prepared to encounter. In addition, cardiac problems as those of our patient should not discourage from substitutive treatment (using L-thyroxine and the gastrointestinal route of absorption), if the age is relatively low.

[The effect of laser hemotherapy on the acid glycosaminoglycan content of the liver and blood plasma in rats in the dynamics of an alcoholic coma]

The aim of the study was determination of the content of acid glycosaminoglicans (GAG) in hepatic tissue and blood plasma of rats in the course of alcoholic coma and in response to laser irradiation of venous blood. The alcoholic intoxication was achieved by introduction of 40% ethanol through a metal probe into the stomach. The content of acid GAG was defined according to Diche. Alcoholic coma caused reduction of GAG levels in hepatic tissue and an increase in blood plasma which were correlated with the severity of neurological state. Laser irradiation of venous blood promoted a trend to normalization of GAG content in the investigated tissues. A relative reduction in GAG plasma levels after laser hemotherapy indicates effectiveness of the conducted therapy.

Brain oxygen tension in severe head injury

OBJECTIVE

Ensuring adequate cerebral oxygenation and perfusion is of fundamental importance in the treatment of patients with acute cerebral disorders. Online continuous monitoring of brain oxygenation is possible with a parenchymal microelectrode that measures local brain oxygen tension. The ultimate question is whether therapeutic approaches can be targeted on the basis of such monitoring. Before this question can be addressed, the technique requires validation in the clinical setting. The frequency of occurrence of low values and its relation to outcome need to be established.

METHODS

One hundred one comatose head-injured patients (Glasgow Coma Scale score < or = 8) were studied. Local brain oxygen tension probes were inserted in an undamaged part of the frontal region. Patients were treated in conformance with the European Brain Injury Consortium guidelines. Outcome at 6 months was determined by Glasgow Outcome Scale score.

RESULTS

Early brain tissue hypoxia was frequently observed, despite aggressive treatment for intracranial pressure and cerebral perfusion pressure. Values lower than 15 mm Hg, for a duration longer than 30 minutes, were observed in 57 patients. Values lower than 10 mm Hg in 42 patients, and lower than 5 mm Hg in 22 patients, were observed during the first 24 hours. Depth and duration of tissue hypoxia were related to outcome and proved to be an independent predictor of unfavorable outcome and death.

CONCLUSION

Monitoring the partial oxygen pressure of local brain tissue is a safe and reliable method for regulating cerebral oxygenation. Because brain tissue hypoxia occurs frequently and is significantly related to poor outcome, future efforts should be aimed at the treatment of brain tissue hypoxia. The effects of such brain hypoxia-targeted treatment need to be established in a multicenter study.

[Hypoglycemia and the brain: metabolism and the mechanisms of neuronal damage]

Hypoglycaemia is a widely distributed pathological state, which develops in case of insulinoma of pancreas, alcohol intoxication, lever and gastrointestinal problems [2, 4, 7, 8, 9, 11, 28]. The most important clinic aspect is that it is associated with treatment of diabetes [2, 7, 8, 19, 28]. Hypoglycaemia may lead to irrecoverable damage to neurons and persistent disruption of the cerebral functions--post-hypoglycaemic encephalopathy; therefore, the metabolic changes resulting from neuroglycopenia and their relationship with neurotic disturbances, as well as the biochemical mechanisms leading to irrecoverable damage to cells are of special interest. Hypoglycaemia is a unique possibility to study these mechanisms, because it leads to cell damage even if there is no disturbance of oxygen supply to brain and intracellular acidosis [35, 38, 133].

Brain O2 consumption and glutamate release during hypoglycemic coma in piglets are temperature sensitive

Hypoglycemic injury in the mature brain is mediated by excitotoxicity, which is worsened by disordered cellular energy metabolism. The role of excitotoxicity in relation to brain energy metabolism during hypoglycemia has not been studied in the immature brain. Brain oxygen consumption (CMRO2) increases during hypoglycemia in piglets, whereas CMRO2 decreases in adult pig models. We tested the hypothesis that increased CMRO2 during hypoglycemic coma is temperature dependent and coincides with increased excitatory amino acids (EAA). We measured cerebral blood flow (CBF), CMRO2, and cortical microdiaysate EAA in pentobarbital-anesthetized piglets during hypoglycemic coma and during 2 h of recovery and in normoglycemic controls. In warmed animals brain temperature was kept normothermic (38.5 degrees C). In unwarmed animals brain temperature was allowed to fall (37.6 degrees C). During hypoglycemia CBF increased similarly in warmed animals and unwarmed animals; CMRO2 increased in warmed animals but not unwarmed animals. Glutamate increased during coma and increased more in warmed animals than unwarmed animals but normalized quickly during recovery. EEG recovered earlier in unwarmed animals. We conclude that during a hypoglycemic coma in the immature brain, CMRO2 and glutamate are increased in a temperature-dependent manner.

Influence of hypoglycemic coma on brain water and osmolality

To study the effects of pronounced hypoglycemia on brain osmolality and brain edema formation, fasted rats were rendered hypoglycemic by injection of insulin, and subjected to 30 min of hypoglycemic coma. Recovery was accomplished by glucose administration. The change in water content in different brain regions was measured as a change in specific gravity after 30 min of hypoglycemic coma, or 30, 60, and 180 min after glucose administration. Plasma and brain tissue osmolality were measured in separate animals. The results show a significant decrease in specific gravity (increase in water content) in all structures measured (caudoputamen, neocortex, hippocampus, and cerebellum) at the end of the period of coma, as well as after 30 min and 60 min of recovery. At 180 min of recovery, brain water was normalized. The edema affected all structures to the same degree regardless of their vulnerability to hypoglycemic damage. Brain tissue osmolality showed a tendency to decrease with decreasing tissue glucose content. The decrease was significant (P<0.01) at 30 min of isoelectric coma. In the recovery phase, normal brain osmolality was restored within 30 min. Measurements of blood-brain barrier (BBB) permeability after 30 min of hypoglycemic coma showed no extravasation of Evan's blue, though a small but significant increase in the permeability for aminoisobutyric acid (AIB) in caudoputamen and in cerebellum was found. To analyze the importance of tissue acidosis for formation of edema, hypoglycemic animals were made acidotic by increasing the CO2 concentration in inspired air to produce an arterial plasma pH of 6.8-6.9. In these animals the edema was of a similar degree to the normocapnic animals, and the permeability for AIB was normal. We conclude that osmolytic mechanisms are not the primary cause of the selective neuronal vulnerability in hypoglycemic coma. Furthermore, the BBB is largely intact during a hypoglycemic insult.

Cerebrospinal fluid levels of biopterin, nitric oxide metabolites, and immune activation markers and the clinical course of human cerebral malaria

Cerebrospinal fluid samples from 130 children who presented with cerebral malaria were investigated to elucidate the impact of biopterin production, NO formation, and local immune activation on the clinical course of this disease. Biopterin levels were significantly lower in patients who were in a deeper coma (P = .02). Cerebrospinal fluid concentrations of NO were significantly higher in children who died than in survivors (P = .037); however, this was not the case for macrophage activation markers, neopterin, and soluble tumor necrosis factor receptor p75 (sTNFR-75). Biopterin, neopterin, and sTNFR-75 but not NO concentrations were significantly related to each other. Low biopterin levels in deep coma are compatible with an impaired local Th1 response, but the low levels could also be due to the scavenging of radicals or to decreased neurotransmitter synthesis. Local production of NO, most likely by nonimmune mechanisms, may be detrimental in cerebral malaria; however, this appears not to be the case for local Th1-mediated immune pathways.

Evidence for altered central noradrenergic function in experimental acute liver failure in the rat

These is increasing evidence to suggest that central noradrenergic mechanisms may contribute to the central nervous system manifestations of acute liver failure. To further elucidate this possibility, extracellular brain concentrations of the monoamines, noradrenaline (NA), dopamine (DA), and serotonin, were measured by high-performance liquid chromatography with electrochemical detection in microdialysates from the extracellular compartment of frontal cortex in rats with acute (ischemic) liver failure at various times during the progression of encephalopathy and brain edema, as well as in obligate control groups of animals. In addition, binding sites for the noradrenergic receptor subtype ligands, [3H]-prazosin (alpha1 sites), [3H]-RX821002 (alpha2 sites), and [125]I-iodopindolol (beta sites), were assessed using quantitative receptor autoradiography in regions of the brains of rats at coma stage of acute liver failure and of control groups of animals. Coma stages of encephalopathy in acute liver failure were associated with selectively increased noradrenaline concentrations (P < .05) and a concomitant selective loss of alpha1 and beta1 sites in frontal cortex and thalamus. These findings add to a growing body of evidence that central noradrenergic function is modified in acute liver failure and suggest that alpha1/beta1 receptor-mediated noradrenergic mechanisms may play a role in the pathogenesis of brain edema and encephalopathy in this condition.

Brainstem auditory evoked potentials (BAEPs) and somatosensory evoked potentials (SEPs) in enteric encephalopathy (EE)

BAEPs and SEPs were studied in 25 patients of enteric encephalopathy in acute phase and the results were compared with 25 healthy control persons. In the study the important observations of BAEPs were delayed peak latency of wave III, wave V and delayed ILP I-V, and of SEPs was prolonged peak latency of N20. The electrophysiological evidence suggests metabolic cause for the coma and the SEP changes were similar to those observed in cerebral malaria reported earlier in this laboratory.

Brain tissue pO2-monitoring in comatose patients: implications for therapy

Monitoring of brain tissue partial pressure of O2 (ti-pO2) is a promising new technique that allows early detection of impending cerebral ischemia in brain-injured patients. The purpose of this study was to investigate the effects of standard therapeutic interventions used in the treatment of intracranial hypertension in comatose patients on cerebral oxygenation. In the neurosurgical intensive care unit ti-pO2, arterial blood pressure, intracranial pressure (ICP), cerebral perfusion pressure (CPP) and jugular bulb oxygen saturation (SjvO2) were prospectively studied (0.1 Hz acquisition rate) in 23 comatose patients (21 with severe traumatic brain injury, 2 with intracerebral hematoma) during various treatment modalities: elevation of CPP with dopamine (n = 35), lowering of the head (n = 22), induced arterial hypocapnia (n = 13), mannitol infusion (n = 16), and decompressive craniotomy (n = 1). Ischemic episodes ('IE' = ti-pO2 < 10 mmHg for > 15 min) within the first week after the insult were always associated with unfavorable neurological outcome. Elevation of CPP from 32 +/- 2 to 67 +/- 4 mmHg significantly improved ti-pO2 by 62% (13 +/- 2 to 21 +/- 1 mmHg) and reduced ICP indicating intact cerebral autoregulation. Further raising CPP from 68 +/- 2 to 84 +/- 2 mmHg did not alter ti-pO2. Mannitol-induced ICP reduction from 23 +/- 1 to 16 +/- 2 mmHg did not affect ti-pO2, nor did lowering of the head from 30 degrees to 0 degree. Hyperventilation from an endtidal pCO2 of 29 +/- 3 to 21 +/- 3 mmHg normalized ICP and CPP, but significantly reduced ti-pO2 from 31 +/- 2 to 14 +/- 3 mmHg. Decompressive craniotomy in a 15-year old patient with refractory intracranial hypertension instantly restored ti-pO2. Based on the present data, our understanding of many interventions previously believed to improve brain oxygenation might have to be re-evaluated. A CPP > 60 mmHg emerges as the most important factor determining sufficient brain tissue pO2. Any intervention used to further elevate CPP does not improve ti-pO2, to the contrary, hyperventilation even bears the risk of inducing brain ischemia.

[Nerve tissue-specific proteins in the assessment of the permeability of the hemato-encephalic barrier in comatose states in children]

The role of functional state of hematoencephalic barrier (HEB) was estimated in terms of development of pathological process in coma. The quantitative determination of neurospecific protein (NSP), exactly of alpha 1 and of alpha 2 cerebral globulins (produced by astrocytes and oligodendroglial cells) was used for estimation of HEB state. The clinical examination of 138 children in comatose state caused by different factor (meningitis, encephalitis, cerebrocranial trauma, infectious toxicosis) was performed. Enzyme immuno-assay of alpha 1 and of alpha 2 cerebral globulins allowed to control HEB's functional state objectively in "brain-blood" direction: in cases of alteration of HEB's function the autoantibodies to NSP may penetrate into cerebral tissue and cause nonspecific reaction in form of edema or inflammation. The membrane stabilizing effect of Dexamethazone was established.

Lactate and excitatory amino acids measured by microdialysis are decreased by pentobarbital coma in head-injured patients

Primary traumatic brain injury and secondary ischemic/hypoxic injury are being increasingly characterized at the neurochemical level. Neurochemical monitoring using microdialysis has shown that these forms of tissue damage share many common features. In particular, anaerobic glycolysis with increased lactate production and release of excitatory amino acids into the extracellular space are seen in both conditions. Clinical microdialysis studies have heretofore focused on methodological issues, establishment of basal analyte values, and clinico-neurochemical correlation. Here we report the neurochemical consequences of therapeutic intervention in head injury. Specifically, induction of thiopental coma to manage severe increased intracranial pressure in seven patients was associated with a 37% reduction of lactate, 59% reduction of glutamate, and 66% reduction in aspartate in the extracellular space of the brain.

Proton magnetic resonance spectroscopy in the evaluation of children with congenital heart disease and acute central nervous system injury

We studied nine infants and children, aged 1 week to 42 months, with severe acute central nervous system injuries associated with cardiac disease or corrective operations by means of single-voxel proton magnetic resonance spectroscopy to determine whether this technique would be useful in predicting neurologic outcome. Proton magnetic resonance spectroscopic data were acquired from the occipital gray and parietal white matter (8 cm3 volume, stimulated echo-acquisition mode sequence with echo time of 20 msec and repetition time of 3.0 seconds) a median of 9 days after operation (range 3 to 42 days). Data were expressed as ratios of areas under metabolite peaks, including N-acetyl compounds, choline-containing compounds, creatine and phosphocreatine, and lactate. Four patients had cerebral insults before operation, one had both a preoperative and a perioperative insult, three had perioperative insults, and one had a prolonged cardiac arrest 2 days after operation. Outcomes (Glasgow Outcome Scale scores) were assigned at discharge and 6 to 12 months after injury. Six patients were in a vegetative state or had severe impairment at discharge, and two still had severe impairment at 6- to 12-month follow-up. Proton magnetic resonance spectroscopy showed lactate in these two patients, along with markedly reduced ratios of N-acetyl compounds to creatine compounds. The other four patients with severe impairment recovered to a level of mild disability at follow-up. Proton magnetic resonance spectroscopy showed no lactate in these four patients; however, one patient showed moderately reduced ratio of N-acetyl compounds to creatine compounds. The three patients who had mild or moderate impairment at discharge showed no lactate and mild or no changes in metabolite ratios; follow-up revealed normal or mild outcomes. Overall, we found that the presence of lactate and markedly reduced ratios of N-acetyl compounds to creatine compounds were predictive of severe outcomes at discharge and long-term follow-up, whereas no lactate and mild or no changes in ratios suggested potential for recovery with at least a mild disability. Continuing investigations are in progress to determine the optimal selection of candidates and timing of proton magnetic resonance spectroscopic studies.

Effect of L-carnitine supplementation on acute valproate intoxication

We analyzed urinary valproate (VPA) metabolites and carnitine concentrations in a child who accidentally ingested 400 mg/kg VPA. The concentration of 4-en VPA, the presumed major factor in VPA-induced hepatotoxicity, was markedly increased, without liver dysfunction or hyperammonemia. The other major abnormality was decreased beta-oxidation and markedly increased omega-oxidation. After L-carnitine supplementation, VPA metabolism returned to normal. The level of valproylcarnitine was not increased and therefore was not affected by L-carnitine. L-Carnitine may be useful in treating patients with coma after VPA overdose.

Glycogen accumulated in the brain following insults is not degraded during a subsequent period of ischemia

The primary objective of this study was to attempt to induce excessive intraglial acidosis during ischemia by subjecting rats to an initial insult which leads to post insult accumulation of glycogen, presumed to accumulate primarily in astrocytes. The initial insults were 15 min of transient forebrain ischemia, 30 min of hypoglycemic coma, and intraperitonial injection of methionine-sulphoximine (MSO). In the first two of these insults, glycogen content in neocortex increased to 6-7 mM kg(-1) after 6 h of recovery, and in MSO-treated animals even higher values were measured 24 h after administration ( 12 mM kg(-1)). In spite of this glycogen loading, the amount of lactate formed during a subsequent ischemic insult (of 5-30 min duration) did not exceed values usually obtained during complete ischemia in animals with normal glycogen contents (tissue lactate contents of 15 mM kg(-1)) This was because appreciable amounts of glycogen (3-7 mM kg(-1)) remained undegraded even after 30 min of ischemia. The undigested part largely reflected the extra amount of glycogen accumulated after the initial insults. It is discussed whether this part is unavailable to degradation by phosphorylase.