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1.
Child Care Health Dev ; 41(6): 882-94, 2015 Nov.
Article in English | MEDLINE | ID: mdl-26355195

ABSTRACT

BACKGROUND: Empirical evidence suggests that the Solihull Approach parenting group, 'Understanding Your Child's Behaviour' (UYCB), can improve child behaviour and parental well-being. However, little is known about parents' in-depth experience of participating in the UYCB programme. This study provides an in-depth qualitative evaluation of UYCB, focussing on possible moderating factors and mechanisms of change that may inform programme development. METHOD: Ten parents (eight mothers and two fathers), recruited from seven UYCB groups across two locations, were interviewed within 7 weeks of completing the group and again 10 months later. Data were analysed using interpretative phenomenological analysis. RESULTS: Four themes were identified: 'Two Tiers of Satisfaction', 'Development as a Parent', 'Improved Self-belief' and 'The "Matthew Effect"'. In summary, the majority of parents were immensely satisfied at both completion and follow-up: they valued an experience of containment and social support and perceived improvement in specific child difficulties, their experience of parenting, their confidence and their coping. Most parents appeared to have developed more reflective and empathic parenting styles, with self-reported improved behaviour management. Theoretical material was well received, although some struggled with technical language. Positive outcomes appeared to be maintained, even reinforced, at follow-up, and were associated with having few initial child difficulties, perceiving improvement at completion and persevering with the recommendations. Two participants, whose children had the most severe difficulties, perceived deterioration and felt that the group was insufficient for their level of difficulties. CONCLUSION: Through in-depth analysis of parental experiences, UYCB appears to achieve its aims and communicate well its theoretical principles, although change may also occur through processes common to other group programmes (e.g. social support). Recommendations, stemming from the experiences of these parents, include simplified language, separate groups for parents with complex needs, greater emphasis on the importance of perseverance, and additional support for parents who appear to be struggling to make changes.


Subject(s)
Child Behavior , Parenting , Parents/psychology , Adolescent , Child , Child, Preschool , Consumer Behavior , England , Evaluation Studies as Topic , Female , Follow-Up Studies , Health Promotion/methods , Humans , Infant , Infant, Newborn , Male , Parent-Child Relations , Parents/education , Program Evaluation , Self Concept
2.
Clin Neurol Neurosurg ; 132: 37-40, 2015 May.
Article in English | MEDLINE | ID: mdl-25764998

ABSTRACT

BACKGROUND: Cerebral tumours can rapidly progress to life-threatening complications yet referral pathways often result in non-significant diagnoses. We aimed to identify the determinants of referrals resulting in significant neurological diagnoses after specialist review. METHODS: We reviewed all urgent brain cancer referrals to the neurology service at a British district general hospital between January 2009 and September 2013. Time to appointment, frequency of significant neurological diagnoses, appropriateness of referrals and referral heterogeneity across GP practices were measured as determinants of non-significant diagnoses. RESULTS: 31/105 patients received significant neurological diagnoses (29.5%), including ten (9.5%) tumours (7 malignant), although 2 patients were admitted prior to clinic. There was significant heterogeneity between primary care physicians in referral frequency (p = 0.008) and significant diagnoses (p = 0.005). Non-significant diagnoses were more common in inappropriate referrals and if patients were unaware of the potential diagnosis. Seizures or subacute focal symptoms were more likely to result in a significant neurological diagnosis than isolated headache syndromes (odds ratio 3.45, 1.34-18.4, p = 0.008). DISCUSSION: Despite a significant number of important neurological diagnoses and tumours, there were frequent inappropriate or low-risk referrals resulting in non-significant diagnoses, particularly if a headache syndrome was the sole reason for referral.


Subject(s)
Brain Neoplasms/diagnosis , Brain Neoplasms/therapy , Referral and Consultation/organization & administration , Adult , Aged , Female , Headache/diagnosis , Humans , Male , Middle Aged , Nervous System Diseases/diagnosis , Nervous System Diseases/therapy , Neurologic Examination , Retrospective Studies , Risk Assessment , Seizures/diagnosis , Treatment Outcome , United Kingdom
3.
Acute Med ; 13(2): 65-7, 2014.
Article in English | MEDLINE | ID: mdl-24940568

ABSTRACT

Some forms of focal epilepsy, including temporal lobe epilepsy, are rarely associated with ictal bradycardia and sinus node arrest. We report a case of a previously healthy man presenting with syncope in whom telemetry revealed sinus arrest. Initial treatment was with permanent pacemaker implantation and it was only following a subsequent grand mal seizure that other symptoms suggestive of temporal lobe epilepsy were documented. Anti-epileptic medication was subsequently commenced with resolution of all symptoms. There are few previously reported cases of syncope and documented sinus node arrest as the presenting feature of temporal lobe epilepsy.


Subject(s)
Epilepsy, Temporal Lobe/diagnosis , Sinus Arrest, Cardiac/etiology , Syncope/etiology , Adult , Anticonvulsants/therapeutic use , Carbamazepine/therapeutic use , Epilepsy, Temporal Lobe/drug therapy , Humans , Male , Pacemaker, Artificial , Seizures/drug therapy , Seizures/etiology , Sinus Arrest, Cardiac/surgery , Syncope/surgery , Telemetry
4.
Aliment Pharmacol Ther ; 33(7): 739-47, 2011 Apr.
Article in English | MEDLINE | ID: mdl-21306407

ABSTRACT

BACKGROUND: The clinical classification of hepatic encephalopathy is largely subjective, which has led to difficulties in designing trials in this field. AIMS: To review the current classification of hepatic encephalopathy and to develop consensus guidelines on the design and conduct of future clinical trials. METHODS: A round table was convened at the 14th International Society for Hepatic Encephalopathy and Nitrogen Metabolism (ISHEN) meeting. Key discussion points were the nomenclature of hepatic encephalopathy and the selection of patients, standards of care and end-points for assessing the treatment and secondary prevention of hepatic encephalopathy. RESULTS: It was generally agreed that severity assessment of hepatic encephalopathy in patients with cirrhosis, whether made clinically or more objectively, should be continuous rather than categorical, and a system for assessing the SONIC (Spectrum of Neuro-cognitive Impairment in Cirrhosis) was proposed. Within this system, patients currently classified as having minimal hepatic encephalopathy and Grade I hepatic encephalopathy would be classified as having Covert hepatic encephalopathy, whereas those with apparent clinical abnormalities would continue to be classified as overt hepatic encephalopathy. Some aspects of the terminology require further debate. Consensus was also reached on the patient populations, standards of care and endpoints to assess clinical trial outcomes. However, some compromises had to be made as there is considerable inter- and intravariability in the availability of some of the more objective surrogate performance markers. CONCLUSIONS: The objectives of the round table were met. Robust, defendable guidelines for the conduct of future studies into hepatic encephalopathy have been provided. Outstanding issues are few and will continue to be discussed.


Subject(s)
Clinical Trials as Topic/standards , Hepatic Encephalopathy/classification , Research Design/standards , Hepatic Encephalopathy/therapy , Humans , Patient Selection , Severity of Illness Index , Terminology as Topic
5.
Neurogastroenterol Motil ; 21(12): 1319-25, 2009 Dec.
Article in English | MEDLINE | ID: mdl-19594690

ABSTRACT

Fatigue is a common debilitating symptom in patients with primary biliary cirrhosis (PBC). The mechanism of fatigue is still poorly understood. However, it has been reported that levels of the steroid dehydroepiandrosterone sulphate (DHEAS) are reduced in plasma of patients with PBC, and substitutive therapy has been suggested to improve fatigue symptoms experienced during the course of this disease. In this study, we tested the effect of DHEAS on whole body fatigue in rats following bile duct ligation (BDL). Fatigue was estimated by the time spent on an electrified grid as a result of falling off a treadmill and by performance of rats on an infrared beam monitor which allows the assessment of travelled distance and stereotypic movement activities. On day 5 after BDL surgery, cholestatic rats exhibited increased whole body fatigue as reflected by significantly increased time spent on the electrified grid, reduced travelled distance and reduced stereotypic movements. Administration of 5 mg kg(-1) of DHEAS to BDL rats for three consecutive days significantly normalized their behaviour. Fatigue scores were also found to be reduced in cirrhotic rats 4 weeks after BDL surgery, and DHEAS treatment for 3 days reduced fatigue scores at this stage. Dehydroepiandrosterone sulphate treatment was sufficient to increase brain levels of DHEAS in the BDL rats in a manner that is significantly and highly correlated with those of plasma DHEAS and brain dehydroepiandrosterone (DHEA). Substitutive therapies with DHEAS or DHEA could represent novel approaches in the management of fatigue due to cholestasis-induced liver failure.


Subject(s)
Bile Ducts/physiology , Cholestasis/complications , Dehydroepiandrosterone Sulfate/therapeutic use , Fatigue/drug therapy , Fatigue/etiology , Animals , Cholestasis/metabolism , Chromatography, High Pressure Liquid , Dehydroepiandrosterone Sulfate/metabolism , Gas Chromatography-Mass Spectrometry , Injections, Intraperitoneal , Ligation , Liver Function Tests , Male , Mass Spectrometry , Motor Activity/drug effects , Motor Activity/physiology , Physical Conditioning, Animal , Rats , Rats, Sprague-Dawley
6.
Neurogastroenterol Motil ; 20(8): 949-57, 2008 Aug.
Article in English | MEDLINE | ID: mdl-18482252

ABSTRACT

Hepatic encephalopathy (HE) is a neuropsychiatric complication of both acute and chronic liver failure characterized by progressive neuronal inhibition. Some neurosteroids are potent positive allosteric modulators of the gamma-aminobutyric acid (GABA)-A receptor complex, and 'increased GABAergic tone' has been proposed to explain the neuroinhibition characteristics of HE. Brain levels of the neurosteroids pregnenolone, allopregnanolone and tetrahydrodesoxycorticosterone (THDOC) and the functional status of the GABA-A receptor complex were assessed in rats following portacaval anastomosis (PCA). Effects of indomethacin, an inhibitor of the 3alpha-hydroxysteroid dehydrogenase enzyme involved in neurosteroid synthesis, on PCA rat locomotor activity and brain neurosteroid levels were also assessed. Significant increases of the neurosteroid pregnenolone (2.6-fold), allopregnanolone (1.7-fold) and THDOC (4.7-fold) were observed in brains of PCA rats. Brain levels of these neurosteroids were in the nanomolar range, sufficient to exert positive allosteric modulatory effects at the GABA-A receptor. Indomethacin (0.1-5 mg kg(-1)) ameliorated dose-dependently the locomotor deficit of PCA rats and concomitantly normalized brain levels of allopregnanolone and THDOC. Increased brain levels of neurosteroids with positive allosteric modulatory actions at the neuronal GABA-A receptor offer a cogent explanation for the notion of 'increased GABAergic tone' in HE. Pharmacological approaches using agents that either reduce neurosteroid synthesis or modulate the neurosteroid site on GABA-A receptor could offer new therapeutic tools for the management and treatment of HE.


Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Ataxia/physiopathology , Brain/drug effects , Indomethacin/pharmacology , Motor Activity/drug effects , Portacaval Shunt, Surgical , Steroids/metabolism , Animals , Brain/metabolism , Brain Chemistry , Desoxycorticosterone/analogs & derivatives , Desoxycorticosterone/chemistry , Desoxycorticosterone/metabolism , Hepatic Encephalopathy/physiopathology , Humans , Male , Molecular Structure , Pregnanolone/chemistry , Pregnanolone/metabolism , Pregnenolone/chemistry , Pregnenolone/metabolism , Rats , Rats, Sprague-Dawley , Receptors, GABA-A/metabolism , Steroids/chemistry
7.
Neurogastroenterol Motil ; 20(6): 671-9, 2008 Jun.
Article in English | MEDLINE | ID: mdl-18282171

ABSTRACT

Fatigue is one of the most common non-specific symptoms associated with several disease states including liver diseases. Recently, it was reported that levels of progesterone metabolites such as allopregnanolone (3alpha,5alpha-tetrahydroprogesterone; 3alpha,5alpha-THP) and isopregnanolone (3beta,5alpha-THP) were increased in plasma of patients with chronic fatigue syndrome. We hypothesize that THP metabolites might be associated with fatigue commonly observed in chronic liver diseases. We evaluated fatigue scores and plasma levels of five progesterone metabolites in 16 patients with primary biliary cirrhosis (PBC), 12 patients with chronic hepatitis C (CHC) and 11 age-matched controls. The fatigue impact scale (FIS) ratio was significantly increased (P < 0.01) in patients with PBC and CHC compared to controls. Plasma levels of 3alpha,5alpha-THP and pregnanolone (3alpha,5beta-THP) were significantly increased in PBC and CHC patients. The other progesterone metabolites, i.e. 3beta,5alpha-THP, 3beta,5beta-THP and 3alpha,5alpha-tetrahydrodeoxycorticosterone were either undetectable or detected only in some patients. Plasma levels of 3alpha,5alpha-THP and 3alpha,5beta-THP were found to be significantly higher in patients with fatigue (P < 0.05), while those of patients without fatigue were not significantly different from controls. Both 3alpha,5alpha-THP and 3alpha,5beta-THP are positive allosteric modulators of the gamma-aminobutyric acid type A (GABA-A) receptor and readily cross the blood-brain barrier. The present preliminary findings suggest that increased inhibition through GABA-A receptors due to the accumulation of neuroinhibitory steroids may represent an important pathophysiological mechanism of fatigue in chronic liver diseases.


Subject(s)
Fatigue/blood , Hepatitis C, Chronic/blood , Liver Cirrhosis, Biliary/blood , Neurotransmitter Agents/blood , Pregnanolone/blood , Severity of Illness Index , Adult , Aged , Fatigue/complications , Fatigue/diagnosis , Female , Hepatitis C, Chronic/complications , Hepatitis C, Chronic/diagnosis , Humans , Liver Cirrhosis, Biliary/complications , Liver Cirrhosis, Biliary/diagnosis , Male , Middle Aged , Neurotransmitter Agents/physiology
10.
Metab Brain Dis ; 20(3): 169-79, 2005 Sep.
Article in English | MEDLINE | ID: mdl-16167195

ABSTRACT

Ammonia is thought to be central in the pathogenesis of hepatic encephalopathy and has been of importance to generations dating back to the early Egyptians. Hippocrates 2500 years ago described 'encephalopathy' simply translated as 'inside head suffering.' Over 1500 papers have been written on hepatic encephalopathy since 1966, but only a minority of these actually refer to the original observation of hepatic encephalopathy and the link with ammonia made by Marcel Nencki and Ivan Pavlov in 1893 with very little acknowledgement being made to the early landmark studies which described the importance of the muscle and kidneys in maintaining ammonia homeostasis as well as the liver and gut. Furthermore, infection was recognized as being an important modulator of brain function by the ancient Greek physicians and philosophers. This review focuses upon the original experiments of Nencki and Pavlov and describes how they fit into what we understand about the pathophysiology and treatment of hepatic encephalopathy today.


Subject(s)
Ammonia/toxicity , Hepatic Encephalopathy/etiology , Ammonia/metabolism , Animals , Hepatic Encephalopathy/therapy , Humans
12.
Indian J Gastroenterol ; 22 Suppl 2: S59-61, 2003 Dec.
Article in English | MEDLINE | ID: mdl-15025258

ABSTRACT

Brain edema and consequent increase in intracranial pressure is a major complication of acute liver failure (ALF) and is a major cause of death in this condition. Rapid accumulation of ammonia in brain has been implicated in the pathogenesis of brain edema in ALF. Increased brain ammonia may cause brain swelling via the osmotic effects of an increase in astrocytic glutamine concentration or by inhibition of glutamate removal from brain extracellular space. Acute liver failure results in altered expression of several genes in the brain, some of which code for proteins involved in central nervous system function such as the glutamate transporter GLT-1, the astrocytic structural protein, glial fibrillary acidic protein, and the water channel protein, aquaporin IV. Loss of expression of GLT-1 results in increased extracellular brain glutamate. Therapeutic measures currently used to prevent and treat brain edema in acute liver failure include mannitol; strategies aimed at lowering of gut ammonia production are generally ineffective. Studies in experimental animals suggest that mild hypothermia or the use of L-ornithine-L-aspartate may be useful in the prevention of brain edema in these patients.


Subject(s)
Brain Edema/metabolism , Brain Edema/prevention & control , Liver Failure, Acute/complications , Ammonia/metabolism , Animals , Astrocytes/metabolism , Brain Edema/physiopathology , Dipeptides/therapeutic use , Humans , Hypothermia, Induced , Intracranial Pressure , Liver Failure, Acute/physiopathology
13.
Metab Brain Dis ; 16(1-2): 55-65, 2001 Jun.
Article in English | MEDLINE | ID: mdl-11726089

ABSTRACT

Hepatic Encephalopathy (HE) is a serious neuropsychiatric condition of both acute and chronic liver failure. Acute liver failure is characterized by rapid evolution of HE and by brain edema. Portal-Systemic encephalopathy (PSE) is particularly prevalent following treatment of portal hypertension or ascites by the TIPS procedure. Available evidence currently suggests that neurotransmission changes rather than brain energy failure are the primary cause of HE. Recent studies both in autopsied brain tissue from HE patients as well as in experimental animal models of HE reveal that liver failure results in altered expression of several genes coding for proteins having key roles in the control of neuronal excitability. Such alterations include decreased expression of the glutamate transporter GLT-1, and increased expression of monoamine oxidase (MAO-A isoform), the "peripheral-type" benzodiazepine receptor (PTBR) as well as constitutive neuronal nitric oxide synthase (nNOS). Such changes result in altered protein expression and in increased extracellular brain glutamate, increased degradation of monoamine neurotransmitters, increased synthesis of neurosteroids with inhibitory properties, and increased production of nitric oxide (respectively) in brain in chronic liver failure. In the case of GLT-1, PTBR, and nNOS, alterations in expression result from exposure to ammonia and/or manganese, two neurotoxic agents shown previously to be increased in brain in liver failure.


Subject(s)
Hepatic Encephalopathy/metabolism , Hepatic Encephalopathy/physiopathology , Neurotransmitter Agents/metabolism , Humans
14.
Metab Brain Dis ; 16(1-2): 95-102, 2001 Jun.
Article in English | MEDLINE | ID: mdl-11726093

ABSTRACT

Evidence from both clinical and experimental studies demonstrates that mild hypothermia prevents encephalopathy and brain edema in acute liver failure (ALF). As part of a series of studies to elucidate the mechanism(s) involved in this protective effect, groups of rats with ALF resulting from hepatic devascularization were maintained at either 37 degrees C (normothermic) or 35 C (hypothermic), and neurological status was monitored in relation to cerebrospinal fluid (CSF) concentrations of ammonia and lactate. CSF was removed via implanted cisterna magna catheters. Mild hypothermia resulted in a delay in onset of encephalopathy and prevention of brain edema, CSF concentrations of ammonia and lactate were concomitantly decreased. Blood ammonia concentrations, on the other hand, were not affected by hypothermia in ALF rats. These findings suggest that brain edema and encephalopathy in ALF are the consequence of ammonia-induced impairment of brain energy metabolism and open the way for magnetic resonance spectroscopic monitoring of cerebral function in ALF. Mild hypothermia could be beneficial in the prevention of severe encephalopathy and brain edema in patients with ALF awaiting liver transplantation.


Subject(s)
Brain Edema/prevention & control , Hypothermia, Induced , Lactic Acid/cerebrospinal fluid , Liver Failure, Acute/complications , Ammonia/blood , Ammonia/cerebrospinal fluid , Animals , Brain/metabolism , Brain Edema/cerebrospinal fluid , Brain Edema/etiology , Energy Metabolism , Hepatic Encephalopathy/metabolism , Hepatic Encephalopathy/therapy , Liver Failure, Acute/cerebrospinal fluid , Liver Failure, Acute/therapy , Male , Rats , Rats, Sprague-Dawley , Water/metabolism
15.
J Neurosci Res ; 66(5): 967-71, 2001 Dec 01.
Article in English | MEDLINE | ID: mdl-11746425

ABSTRACT

Cerebral edema and hepatic encephalopathy are major complications of acute liver failure. Brain herniation caused by increased intracranial pressure as a result of cell swelling is the major cause of death in this condition. Evidence available currently suggests that the rapid accumulation of ammonia by the brain is the major cause of the central nervous system complications of acute liver failure. Increased brain ammonia may cause cell swelling via the osmotic effects of an increase in astrocytic glutamine concentrations or by inhibition of glutamate removal from brain extracellular space. Acute liver failure results in altered expression of several genes in brain, some of which code for important proteins involved in CNS function such as the glucose (GLUT-1) and glutamate (GLT-1) transporters, the astrocytic structural protein glial fibrillary acidic protein (GFAP) the "peripheral-type" benzodiazepine receptor (PTBR) and the water channel protein, aquaporin IV. Loss of expression of GLT-1 results in increased extracellular brain glutamate in acute liver failure. Experimental acute liver failure also results in post-translational modifications of the serotonin and noradrenaline transporters resulting in increased extracellular concentrations of these monoamines. Therapeutic measures currently used to prevent and treat brain edema and encephalopathy in patients with acute liver failure include mild hypothermia and the ammonia-lowering agent L-ornithine-L-aspartate.


Subject(s)
Ammonia/metabolism , Astrocytes/metabolism , Gene Expression Regulation/physiology , Hepatic Encephalopathy/metabolism , Liver Failure, Acute/complications , Animals , Excitatory Amino Acid Transporter 2/genetics , Excitatory Amino Acid Transporter 2/metabolism , Glial Fibrillary Acidic Protein/genetics , Glial Fibrillary Acidic Protein/metabolism , Hepatic Encephalopathy/physiopathology , Hepatic Encephalopathy/therapy , Humans , Liver Failure, Acute/metabolism , Liver Failure, Acute/physiopathology , Receptors, GABA-A/genetics , Receptors, GABA-A/metabolism
17.
Inhal Toxicol ; 13(12): 1151-63, 2001 Dec.
Article in English | MEDLINE | ID: mdl-11696878

ABSTRACT

The use of the additive methylcyclopentadienyl manganese tricarbonyl in unleaded gasoline has resulted in increased attention to the potential toxic effects of manganese (Mn). Hypothetically, people with chronic liver disease may be more sensitive to the adverse neurotoxic effects of Mn. In this work, bioaccumulation of Mn, as well as histopathology and neurobehavioral damage, in end-to-side portacaval anastomosis (PCA) rats exposed to Mn phosphate via inhalation was investigated. During the week before the PCA operation, 4 wk after the PCA operation, and at the end of exposure, the rats were subjected to a locomotor evaluation (day-night activities) using a computerized autotrack system. Then a group of 6 PCA rats (EXP) was exposed to 3050 microg m(-3) (Mn phosphate) for 8 h/day, 5 days/wk for 4 consecutive weeks and compared to a control group (CON), 7 PCA rats exposed to 0.03 microg m(-3). After exposure, the rats were euthanized and Mn content in tissues and organs was determined by neutron activation analysis. The manganese concentrations in blood (0.05 microg/g vs. 0.02 microg/g), lung (1.32 microg/g vs. 0.24 microg/g), cerebellum (0.85 microg/g vs. 0.64 microg/g), frontal cortex (0.87 microg/g vs. 0.61 microg/g), and globus pallidus (3.56 microg/g vs. 1.33 microg/g) were significantly higher in the exposed group compared to the control group (p <.05). No difference was observed in liver, kidney, testes, and caudate putamen between the two groups. Neuronal cell loss was assessed by neuronal cell counts. The loss of cells in globus pallidus and caudate putamen as well as in frontal cortex was significantly higher (p <.05) for the EXP group. Assessment of the locomotor activities did not reveal any significant difference. This study constitutes a first step toward our understanding of the potential adverse effects of Mn in sensitive populations.


Subject(s)
Neurotoxicity Syndromes/pathology , Organometallic Compounds/metabolism , Organometallic Compounds/toxicity , Portacaval Shunt, Surgical , Administration, Inhalation , Animals , Brain/pathology , Circadian Rhythm/drug effects , Male , Manganese/pharmacokinetics , Motor Activity/drug effects , Neurons/drug effects , Neurons/pathology , Neurotoxicity Syndromes/psychology , Particle Size , Pilot Projects , Rats , Rats, Sprague-Dawley
19.
Brain Res ; 918(1-2): 10-9, 2001 Nov 09.
Article in English | MEDLINE | ID: mdl-11684037

ABSTRACT

We have characterized the temporal changes in iNOS, MnSOD and nitrotyrosine immune reactivity in a rat model of permanent middle cerebral artery occlusion under acute hyperglycemic or normoglycemic conditions followed by either 3- or 24-h recovery. We found that the macroscopic labeling pattern for all three antibodies colocalized with the ischemic core and penumbra which was determined by cresyl violet histological evaluation in adjacent sections. Hyperglycemia induced prior to ischemia resulted in earlier infarction which correlated with increased immunoreactivity for iNOS, MnSOD and nitrotyrosine. In the penumbral region of the frontal cortex, labeling of specific cell structures was largely limited to cortical neurons near the corpus callosum and was apparent earlier in the hyperglycemic rats. Increased polymorphonuclear leukocyte adhesion in blood vessels was observed at 24 h in the hyperglycemic group. At both of the recovery times studied, we observed only minor vascular staining for nitrotyrosine and none for iNOS. Our results are consistent with hyperglycemia resulting in an early and concomitant increase in both superoxide and nitric oxide production which can lead to peroxynitrite formation that then nitrates tyrosine residues. It would appear that hyperglycemic ischemia contributes to the early induction of key enzymes involved in nitric oxide bioavailability.


Subject(s)
Brain Ischemia/complications , Cerebral Cortex/enzymology , Hyperglycemia/complications , Nitric Oxide Synthase/metabolism , Superoxide Dismutase/metabolism , Tyrosine/analogs & derivatives , Tyrosine/metabolism , Animals , Blood Vessels/enzymology , Blood Vessels/pathology , Blood Vessels/physiopathology , Brain Ischemia/enzymology , Brain Ischemia/physiopathology , Cerebral Cortex/injuries , Cerebral Cortex/physiopathology , Cerebrovascular Circulation/physiology , Disease Models, Animal , Hyperglycemia/enzymology , Hyperglycemia/physiopathology , Immunohistochemistry , Infarction, Middle Cerebral Artery/complications , Infarction, Middle Cerebral Artery/enzymology , Infarction, Middle Cerebral Artery/physiopathology , Male , Nerve Degeneration/enzymology , Nerve Degeneration/pathology , Nerve Degeneration/physiopathology , Neuroglia/enzymology , Neuroglia/pathology , Neurons/enzymology , Neurons/pathology , Nitric Oxide/metabolism , Oxygen/metabolism , Rats , Rats, Sprague-Dawley
20.
J Neurochem ; 78(3): 560-8, 2001 Aug.
Article in English | MEDLINE | ID: mdl-11483659

ABSTRACT

Although earlier studies on thiamine deficiency have reported increases in extracellular glutamate concentration in the thalamus, a vulnerable region of the brain in this disorder, the mechanism by which this occurs has remained unresolved. Treatment with pyrithiamine, a central thiamine antagonist, resulted in a 71 and 55% decrease in protein levels of the astrocyte glutamate transporters GLT-1 and GLAST, respectively, by immunoblotting in the medial thalamus of day 14 symptomatic rats at loss of righting reflexes. These changes occurred prior to the onset of convulsions and pannecrosis. Loss of both GLT-1 and GLAST transporter sites was also confirmed in this region of the thalamus at the symptomatic stage using immunohistochemical methods. In contrast, no change in either transporter protein was detected in the non-vulnerable frontal parietal cortex. These effects are selective; protein levels of the astrocyte GABA transporter GAT-3 were unaffected in the medial thalamus. In addition, astrocyte-specific glial fibrillary acidic protein (GFAP) content was unchanged in this brain region, suggesting that astrocytes are spared in this disorder. Loss of GLT-1 or GLAST protein was not observed on day 12 of treatment, indicating that down-regulation of these transporters occurs within 48 h prior to loss of righting reflexes. Finally, GLT-1 content was positively correlated with levels of the neurofilament protein alpha-internexin, suggesting that early neuronal drop-out may contribute to the down-regulation of this glutamate transporter and subsequent pannecrosis. A selective, focal loss of GLT-1 and GLAST transporter proteins provides a rational explanation for the increase in interstitial glutamate levels, and may play a major role in the selective vulnerability of thalamic structures to thiamine deficiency-induced cell death.


Subject(s)
ATP-Binding Cassette Transporters/metabolism , Astrocytes/physiology , Down-Regulation/physiology , Glutamic Acid/metabolism , Thalamus/metabolism , Wernicke Encephalopathy/metabolism , Amino Acid Transport System X-AG , Animals , Antimetabolites/pharmacology , Biological Transport , Carrier Proteins/metabolism , Disease Models, Animal , Humans , Immunoblotting , Immunohistochemistry , Intermediate Filament Proteins , Male , Parietal Lobe/metabolism , Pyrithiamine/pharmacology , Rats , Rats, Sprague-Dawley , Statistics as Topic , Thiamine Deficiency/chemically induced , Thiamine Deficiency/metabolism , Wernicke Encephalopathy/chemically induced
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