Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We investigated the function of monoaminergic neuron in the brainstem by measuring its metabolites using in vivo microdialysis following experimental subarachnoid hemorrhage in rats. Dialysis probe was implanted into the nucleus tractus solitarius (NTS) and continuous perfusion was then started. The perfusates were collected every 10-20 minutes and assayed by high-performance liquid chromatography (HPLC) with electrochemical detection (ECD). The main monoamine metabolites in extracellular space measured in NTS were 3,4-dihydroxy-phenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA). The extracellular content of DOPAC was abruptly increased after cisternal autologous blood (0.3ml) injection, reached a peak at 20-40 minutes, and then decreased over 120 minutes. The content of HVA and 5-HIAA changed as well as DOPAC. These results showed non-specific response for ischemia of the brainstem, because the similar changes were seen after cisternal saline injection. The disappearance rate of monoamine metabolites after pargyline administration (75 mg/kg, i.p.) at various time periods after cisternal blood injection was most rapid at 2 days after SAH and recovered gradually. In particular the decline curve of DOPAC consisted of two compartments and early compartment was disturbed more severely than late compartment. These results indicate that the functional disturbance of nerve terminals is more severe than nerve cell body in adrenergic neurons.
 ...
PMID:[Changes in monoamine metabolites measured by in vivo microdialysis of the brainstem following experimental subarachnoid hemorrhage in rats]. 137 47

Many patients survive aneurysmal SAH with minimal neurological deficits, but are at risk for developing further neurological insult from ischemia resulting from cerebral vasospasm. Nimodipine has proven to be effective in preventing this complication in a majority of patients studied, with hypotension the most severe adverse effect. Nimodipine alone, or in combination with other methods of therapy, may significantly improve the neurological outcome in this select patient population.
 ...
PMID:Nimodipine: the use of calcium antagonists to prevent vasospasm following subarachnoid hemorrhage. 214 68

The timing of surgery for the ruptured aneurysm (SAH) remains controversial. After the period of delayed surgery, the early surgery is now more and more frequently advocated. This paper, study our experience in aneurysm surgery in two different periods, considering only patients admitted in grades I to IV, excluding grade V patients (deep coma, decerebration). During the former period (1972-1984) 328 patients were admitted and considered for delayed surgery, usually during the second week following SAH. 94.5% of patients were operated upon. 5.5% patients died before surgery, from ischemia (3%) or from rebleeding (2.5%). 38.5% were admitted between (D.O-D3) after SAH, D.O being the day of SAH. Only 5.7% were operated upon between D.O-D3. The higher peak of surgery was during the second week (41.8%) and during the third week (39.2%). During the later period (1985-1988) 106 patients were admitted, 50% of them between D.O and D3 after SAH. Every patient was operated upon. The patients admitted between D.O and D3 were operated upon as follows: between D.O and D3 = 32.1%, between D4 and D6 = 22.6%, between D7 and D15 = 34%, after D16 = 11.3%. The analysis of these sub-groups demonstrates that the distribution was related to the age and clinical status. Patients being awake and under 50 years of age were considered for early surgery. Patients being obnubilated or stuporous, and over 50 years of age were planned for delayed surgery. Angiographic spasm and extension of blood in CT Scan were taken in consideration to a lesser degree.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:[The same question for the past 20 years: when should a ruptured intracranial aneurysm be surgically treated? (Experience with 434 cases)]. 228 2

During cerebral aneurysms surgery, brain tissue may suffer for global or local ischemia due to deliberate hypotension and surgical manoeuvres. Somatosensory evoked potentials (SEPs) can detect functional derangements consequent to hypoxia, before a permanent brain damage is produced. Forty two patients, undergoing cerebral aneurysms surgery for treatment of SAH, were evaluated intraoperatively with SEP recordings. It has been stressed that no permanent neurological damage is to be expected if the absolute value of Central Conduction Time (CCT) does not exceed 9.5 ms for 10 min at least and the cortical waves are visible throughout the whole procedure. SEP changes are strictly related with MAP decrease and surgical handlings.
 ...
PMID:Intra-operative monitoring by means of somatosensory evoked potentials during cerebral aneurysms surgery. 228 8

We investigated the effect of S-adenosyl-L-methionine (SAMe) on the prevention of the delayed neuronal death in rats subjected to transient and brief forebrain ischemia. As the results, SAMe dose-dependently protected the hippocampal CA1 neurons from degeneration and necrosis, whose effect was suppressed by simultaneous administration of S-adenosyl-L-homocysteine, a potent inhibitor in transmethylation. No protective effect was observed in CDP-choline, phosphatidylcholine and L-methionine. Therefore, it is necessary for the prevention of the delayed neuronal death to enhance cerebral SAMe level and to activate transmethylation using SAMe as a methyl donor in postischemic brain.
 ...
PMID:S-adenosyl-L-methionine protects the hippocampal CA1 neurons from the ischemic neuronal death in rat. 333 27

Knowledge of the local incidence of aneurysm rupture permits the conclusion that almost every patient in the population of 933,800 persons served by the authors' institution who was stricken by this catastrophe and survived long enough to be transported was treated at this center (121 patients during 34 months). Of these, 9.1% were admitted late (greater than 72 hours after subarachnoid hemorrhage (SAH]; of the remaining cases, 94.5% were seen within 24 hours and 50% within 6 hours post-SAH. Of the 121 patients, 10% were neurologically devastated on arrival, a late operation was planned for 19%, and the earliest possible surgery and nimodipine administration was selected for 71%. In this latter group, 50% of the operations were begun within 24 hours and 76% within 48 hours post-SAH. Sixty percent of all mortality and morbidity could be linked to the initial aneurysm bleed. The remaining 40% could be ascribed to potentially avoidable causes of unfavorable outcome. No less than 9.6% of all patients admitted within 24 hours after SAH suffered from "ultra-early" rebleeding during transportation or preparation for operation. The mortality rate from such rebleeding was 7.4%, compared with the 9.1% combined mortality rate from complications and late ischemia.
 ...
PMID:Significance of "ultra-early" rebleeding in subarachnoid hemorrhage. 337 85

Purine nucleotides, nucleosides, nucleobases, dinucleotides and nucleosides derivatives from acid-extracted rat liver and diaphragm were separated and quantitated by reversed-phase ion-pair high-performance liquid chromatography with a mobile phase composed of 90 mM potassium phosphate, 15 mM tetrabutylammonium hydroxide and a 1-30% methanol gradient. During 5 min of ischemia, adenine and guanine nucleotides decreased along with significant declines in NAD and increases in adenosine, inosine, hypoxanthine, xanthine, NADP and adenylosuccinate. Nitrobenzylthioinosine by gavage (5 mg/kg per day for five days) increased adenosine levels but without any alteration in nucleobase levels. Adenosine was shuttled to every available intracellular reservoir which included in declining order of magnitude GDP greater than adenosylhomocysteine greater than adenosine greater than ADP greater than AMP greater than IMP = XMP = GMP.
 ...
PMID:Demonstration of the adenosine reservoirs with nitrobenzylthioinosine in liver and diaphragm by high-performance liquid chromatography. 339 39

Experiments were carried out to test the hypothesis whether adenosine produced by ATP catabolism during ischemia can be trapped with L-homocysteine and be re-utilized during reperfusion. During intraatrial infusion of L-homocysteine (100 mg/kg/h), the ischemic accumulation of adenine nucleosides and oxypurines in dog myocardium was found to be less than 50% of that during control ischemia. A high proportion of adenosine was recovered as S-adenosyl-L-homocysteine. On reperfusion, S-adenosyl-L-homocysteine. On reperfusion, S-adenosyl-L-homocysteine tissue content remained high. After 3 hours of reperfusion approximately 50% of the accumulated S-adenosyl-L-homocysteine were still found in the tissue. Infusion of L-homocysteine did not cause an accumulation of S-adenosyl-L-homocysteine in the nonischemic myocardial tissue. L-homocysteine treatment caused a further depletion of ATP during reperfusion after 30 minutes of ischemia, which can be interpreted as a toxic effect. We conclude that L-homocysteine is indeed able to trap adenosine produced by ATP breakdown, but the reaction is not readily reversible and is therefore not useful for quick restoration of postischemic ATP levels.
 ...
PMID:Intracellular trapping of adenosine during myocardial ischemia by L-homocysteine. 375 92

Despite its efficacy in preventing rebleeding, the anticipated strong trend in favor of early intracranial surgery has not been achieved. Early intracranial operation remains a useful choice in the management of recent SAH in good-risk patients, but patients must be carefully selected on an individual basis. Many patients will undoubtedly benefit from early surgery but it is not a panacea. Further investigation of surgical treatment in combination with improved preoperative and postoperative medical therapy will be required to ameliorate the outcome of SAH. In particular, the prevention and treatment of cerebral infarction deserves attention. The results of the antifibrinolytic and timing of intracranial surgery studies point to the need for an effective prevention treatment regimen for vasospasm. Further studies about the efficacy of calcium channel blocking drugs in prevention of ischemia after SAH are needed among patients given antifibrinolytic drugs or having early operation. All the advances in treatment are predicated on prompt diagnosis of SAH in good-condition patients. The medical community needs to maintain a high degree of vigilance for the diagnosis of SAH in all patients complaining of a new, unusual or severe headache. Early referral to properly equipped and staffed medical facilities remains a keystone to effective treatment of SAH.
 ...
PMID:Early management of the patient with recent aneurysmal subarachnoid hemorrhage. 381 Jul 3

The coronary vasodilator adenosine can be formed in the heart by breakdown of AMP or S-adenosylhomocysteine (SAdoHcy). The purpose of this study was to get insight into the relative importance of these routes of adenosine formation in both the normoxic and the ischemic heart. A novel HPLC method was used to determine myocardial adenosine and SAdoHcy. Accumulation of SAdoHcy was induced in isolated rat hearts by perfusion with L-homocysteine thiolactone or L-homocysteine. The release of adenosine, inosine, hypoxanthine, xanthine and uric acid was determined. Additional in vitro experiments were performed to determine the kinetic parameters of S-adenosylhomocysteine hydrolase. During normoxia the thiolactone caused a concentration-dependent increase in SAdoHcy. At 2000 microM of the thiolactone an SAdoHcy accumulation of 0.49 nmol/min per g wet weight was found during normoxia. L-Homocysteine (200 microM) caused an increase of 0.37 and 4.17 nmol SAdoHcy/min per g wet weight during normoxia and ischemia, respectively. The adenosine concentration in ischemic hearts was significantly lower when homocysteine was infused (6.2 vs. 11.5 nmol/g; P less than 0.05). Purine release was increased 4-fold during ischemia. The Km for hydrolysis of SAdoHcy was about 12 microM. At in vitro conditions favoring near-maximal SAdoHcy synthesis (72 microM adenosine, 1.8 mM homocysteine), the synthesis rate in homogenates was 10 nmol/min per g wet weight. From the combined in vitro and perfusion studies, we conclude that S-adenosylhomocysteine hydrolase can contribute significantly to adenosine production in normoxic rat heart, but not during ischemia.
 ...
PMID:Myocardial S-adenosylhomocysteine hydrolase is important for adenosine production during normoxia. 400 94


1 2 3 4 Next >>