Study on pharmacological effect of bile salts, sodium scymnol sulfate, from Rhizoprionodon acutus. I. Effect of scymnol, chimaerol and sodium scymnol sulfate on cerebral anoxia

The effects of scymnol, chimaerol and sodium scymnol sulfate, prepared from the bile of Rhizoprionodon acutus, on cerebral anoxia were investigated in experimental models of hypoxia, ischemia and histotoxic anoxia in mice. Scymnol, at a dose of 100 mg/kg, showed a significant protective action against cerebral anoxia in all of the models studied and significantly increased the partial oxygen pressure of the arterial blood. The anti-anoxic activity of scymnol was found to be slightly greater than that of idevenone. A similar protective effect of sodium scymnol sulfate was seen at doses higher than 100 mg/kg. The survival time on hypoxia was significantly prolonged in the animals pretreated with chimaerol.

Protective effect of hachimi-jio-gan, an oriental herbal medicinal mixture, against cerebral anoxia

The protective effect of Hachimi-jio-gan (HJ) against cerebral anoxia was investigated with various experimental models in mice. Minimal effective dose of HJ which significantly prolonged the survival time was 0.5 g/kg, p.o. for normobaric hypoxia and 0.5 g/kg, p.o. for KCN- (4 mg/kg, i.v.) induced anoxia. HJ reduced the duration of coma induced by a sublethal dose of KCN (1.8 mg/kg, i.v.) in a dose-dependent manner. Furthermore HJ potentiated the anti-anoxic effect of physostigmine and the effect of HJ was diminished by the treatment with atropine.

Cocaine induces rapid loss of intracellular free Mg2+ in cerebral vascular smooth muscle cells

Acute exposure of cultured canine cerebral vascular smooth muscle cells to low concentrations of cocaine HCl (10(-9) to (10(-7) M) resulted in significant, rapid (1 min) loss of intracellular free Mg ions ([Mg2+]i); these reductions (12-25%) in [Mg2+]i were reversible upon exposure to normal, Mg(2+)-containing physiological salt solution. These findings help to provide a rational basis for why cocaine can result in cerebrovasospasm and stroke.

Quinolinate potentiates the neurotoxicity of excitatory amino acids in hypoxic neuronal tissue in vitro

Excitatory amino acids (EAAs) in the central nervous system are involved in both neurotransmission and neurotoxicity. Quinolinate (QUIN) is a neurotoxic endogenous tryptophan metabolite that has been linked to Huntington's disease, Alzheimer's disease, and many inflammatory diseases. We used the rat hippocampal slice preparation and its electrophysiology to study the interaction of QUIN with glutamate receptor agonists such as N-methyl-D-aspartate (NMDA), glutamate, aspartate, kainate, and AMPA ((R,S)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate). The majority of slices could tolerate an exposure to 10-min hypoxia (86% recovered their neuronal function), but doses of glutamate receptor agonists which were harmless under normoxic conditions, significantly reduced this recovery rate under hypoxic conditions. QUIN, at doses that even under hypoxic conditions were innocuous (20-50 microM), potentiated the neurotoxic effects of all the glutamate receptor agonists tested in hypoxic hippocampal slices. The NMDA antagonist D,L-2-amino-5-phosphonovalerate blocked this potentiation while 7-chlorokynurenate, at a dose sufficient to block the effect of NMDA alone, was ineffective in blocking the potentiation of NMDA toxicity by QUIN. Non-toxic analogues of QUIN (6-methyl-QUIN and 2,3-pyrazine dicarboxylate) were also able to potentiate NMDA toxicity in hypoxic slices. The results of these experiments provided indirect evidence that QUIN is an endogenous potentiator of the NMDA and the kainate receptor subtypes; therefore, we postulate that QUIN has a specific modulatory binding site on all glutamate receptor subtype complexes. Regardless of its site of interaction, the importance of QUIN as a potentiator of the agonistic activation of these receptors cannot be overemphasized.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies on the effects of endothelin-1 (ET-1) and endothelin-3 (ET-3) in brain hypoxia and on the participation of brain prostanoids in their actions

The effects of endothelin-1 (ET-1) and endothelin-3 (ET-3) in brain hypoxia have been studied in mice using the following experimental models: hypobaric hypoxia induced by low atmospheric pressure, histotoxic hypoxia induced by 12.5 mg/kg KCN i.p., and complete ischemia induced by decapitation. ET-1 and ET-3 were injected intracerebroventricularly (i.c.v.) 15 min before the tests. Forebrain tissue concentrations of 6-keto-PGF1 alpha and thromboxane B2 (TxB2) were measured 15 min following i.c.v. administration of ET-1 (5 pmol/mouse) and ET-3 (10 pmol/mouse). ET-1 (1-5 pmol/mouse) and ET-3 (5-25 pmol/mouse) showed a dose-dependent increase in the survival/gasping time in all models of hypoxia. The effect reached its maximum between 15 and 30 min after ET administration and lasted for about 120 min. ET-1 and ET-3 did not significantly change the brain levels of 6-keto-PGF1 alpha and TxB2. The protective effect of ET-1 and ET-3 was unexpected, because endothelins (ETs) are the most potent vasoconstrictors known, and in doses close to those used in this study they cause vasoconstriction and decrease in cerebral blood flow. The protection was not likely to be due either to stimulation of the endogenous release of prostacyclin (PGI2) or to a decrease in the deleterious prostanoid thromboxane A2 (TxA2). Additional experiments are necessary to explain the cerebroprotective effects of ET-1 and ET-3.

Is admission after intravenous heroin overdose necessary?

STUDY OBJECTIVES

To investigate the time of onset and incidence of complications in patients presenting to the emergency department with an IV heroin overdose and the need for routine admission of such patients.

METHODS

A retrospective chart review of hospital and emergency medical service records of 124 patient visits involving IV heroin overdose over a five-month period. We also reviewed the death certificates of 115 persons having succumbed to a narcotic overdose over a 44-month period and compared these with our hospital records.

SETTING

Urban county hospital.

TYPE OF PARTICIPANTS

Patients presenting to the ED with an IV heroin overdose.

RESULTS

There were five deaths in the ED, 12 hospital admissions, and 107 patients who were discharged home. Neither delayed onset of pulmonary edema nor recurrence of respiratory depression was observed. Of the 115 persons having succumbed to a narcotic overdose, eight had been seen previously at our hospital for a heroin overdose. There is no evidence that any of these eight deaths would have been prevented by a 24-hour hospital observation period.

CONCLUSION

Complications arising from an IV overdose of heroin are usually evident on arrival in the ED or shortly thereafter. On retrospective review we have found no evidence that admission to the hospital and 24 hours of observation are of benefit to patients who are awake, alert, and lacking evidence of pulmonary complications after an IV heroin overdose.

Ouabain-induced changes of calcium and potassium in slices of hippocampus of the rat: comparison to hypoxia and effect of R 56865

Simple and reliable in vitro models of cerebral ischaemia are important for the identification of antiischaemic/antihypoxic compounds. Alterations of the concentrations of potassium and calcium were recorded in slices of hippocampus of the rat. The slices were subjected to hypoxia in the presence and absence of intoxication with glucose or ouabain (1 mmol/l). Normoxic slices of hippocampus showed an extracellular space of 57% and a tissue concentration of potassium of 45 mmol/kg wet wt. A cellular concentration of potassium of 92 mmol/kg was calculated. Hypoxia, in the presence of glucose, only slightly reduced tissue concentrations of potassium and did not influence concentrations of calcium. Omission of glucose during hypoxia led to tissue concentrations of potassium below 10 mmol/kg, within 10-30 min of hypoxia. Concentrations of calcium only increased from 3.3 to 3.5 mmol/kg after 30 min of hypoxia, without glucose. Intoxication with ouabain is proposed as alternative experimental model of ionic movements, associated with cerebral ischaemia/hypoxia. Tissue concentrations of potassium fell rapidly to values below 10 mmol/kg, within 5 min and concentrations of calcium rose to 5.2 mmol/kg, within 30 min of intoxication with ouabain. In quantitative terms, the model for cerebral ischaemia with intoxication with ouabain is suggested to be superior to the model based on hypoxia without glucose. To verify intoxication with ouabain as an experimental model for ischaemic/hypoxic insults, the effect of an investigational drug with antiischaemic/hypoxic properties (R 56865) was evaluated in the model. The drug R 56865 produced dose-dependent attenuation of the fall in tissue concentrations of potassium, between 3 x 10(-7) and 5 x 10(-6) mol/l.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebral lesions in preterm infants after tocolytic indomethacin

The incidence and type of cerebral lesions in 159 infants born before 30 weeks gestation were studied, using ultrasound. Indomethacin was given as part of tocolytic management to mothers with a high incidence of early rupture of membranes and preterm labour; and 76 fetuses were exposed to the drug as a result. For the remaining 83 pregnancies, in which there was a high incidence of chronic fetal distress and in utero hypoxia, tocolysis was either not started or limited to fenoterol. The neonatal course was similar for both groups of infants, except that patent ductus arteriosus was less commonly diagnosed in the 76 infants exposed to indomethacin. However, the incidence of periventricular leukomalacia was increased among infants exposed to any tocolytic agent; and cystic lesions occurred more commonly in those exposed to indomethacin.

MK-801 ameliorates delayed amnesia, but potentiates acute amnesia induced by CO

The effects of non-competitive N-methyl-D-aspartate receptor antagonists on amnesia induced by carbon monoxide (CO) were investigated, since they have neuroprotective effects on delayed degeneration induced by ischemia. In the mice exposed to CO, acute and delayed amnesia were induced. (+)-MK-801 and (-)-MK-801 improved the delayed amnesia, but the effects of phencyclidine (PCP) were weak. (+)-MK-801 and PCP potentiated the acute amnesia. From these results, it is suggested that there is a stereoselectivity in the effects of MK-801 on CO-induced amnesia and that CO-induced delayed amnesia animals could be used as an ischemic amnesia model.

Fatal angioedema associated with enalapril

A 65-year-old male with a long history of congestive heart failure presented to the emergency room with facial swelling 7 h after the first dose of enalapril. He was treated with diphenhydramine and hydrocortisone which improved his angioedema. However, there was a profound relapse of the angioedema followed by respiratory arrest. He suffered severe anoxic brain damage and died five days later. It is likely that the long half-life of enalapril lead to this rebound phenomenon. Enalapril induced angioedema is reviewed with suggestions for management.

Dental anesthetic death. An unusual autoerotic episode

The details of an unusual autoerotic death are presented; the postulated method of induction of cerebral hypoxia was inhalation of nitrous oxide from a dental anesthetic machine; the theme of dental anesthesia, presumably an elaborate bondage fetish, recurred in documentary material found at the scene.

[Pharmacological studies on Y-8894. (IV). Ameliorative effect on a cerebral energy metabolism disorder induced by KCN]

The amelioration of energy metabolic disturbance in cerebral anoxia is valuable for the treatment of various cerebral ischemic diseases and insufficiency. In this study, the effect of Y-8894 on the cerebral energy metabolism was investigated using a KCN-induced cerebral anoxia model with mice. The intravenous injection of a lethal dose of KCN (2.5 mg/kg) induced rapid and marked decreases of brain glucose, phosphocreatine and ATP contents, with a remarkable enhancement of lactate and AMP levels, indicating a severe disorder of the cerebral energy metabolism. This phenomenon was also shown by an irreversible deterioration of the energy charge potential (ECP), an index of the cerebral energy state. The treatment with Y-8894 (30 mg/kg, i.p.) remarkably ameliorated this KCN-induced energy metabolic disturbance: markedly reducing the changes in brain phosphocreatine, glucose and lactate contents, while keeping ATP, AMP and ECP at nearly their normal levels. In addition, these changes in the Y-8894 treated group recovered promptly to normal, whereas those in the control group were irreversible. In normal mice, Y-8894 induced a significant increase in the cerebral glucose content without affecting either the cerebral glycolytic metabolism or the energy state. The present findings suggest that Y-8894 has an ameliorative effect on the cerebral energy metabolic disturbance, and this effect likely plays an important role in the improvement of amnesia and other neurological deficits related to cerebral anoxia.

[Effects of 4-(o-benzylphenoxy)-N-methylbutylamine hydrochloride (bifemelane) on the synthesis of acetylcholine in anemic hypoxia]

Pretreatment of mice with 4-(o-benzylphenoxy)-N-methylbutylamine hydrochloride (bifemelane) protected against effects of anemic hypoxia. Befemelane delayed the loss of the righting reflex (from 17.8 +/- 1.3 to 21.9 +/- 1.2 min, p less than 0.05) and death (from 19.6 +/- 1.3 to 23.3 +/- 1.1, p less than 0.05) in mice with anemic hypoxia (induced with NaNO2). Pretreatment with bifemelane ameliorated the reduction in the synthesis of acetylcholine from labeled precursors in anemic hypoxia. Namely, it reduced the inhibition of acetylcholine synthesis from labeled choline (from 3.8 +/- 0.5 to 9.4 +/- 1.2 pmole/mg protein at 30 mg/kg, p less than 0.01), but not significant at 15 mg/kg. However it (15 mg/kg) caused a significant increase in the incorporation of [U-14C] glucose into acetylcholine compared to the value for hypoxic animals (from 5 +/- 0.5 to 9 +/- 1 dpm/mg protein, p less than 0.001). Under normal conditions, concentrations of acetylcholine and glucose in the brain were significantly increased by the 30 mg/kg of bifemelane, while the synthesis of acetylcholine from choline was significantly decreased. This reduction of synthesis might be caused by the increased acetylcholine concentrations in the brain. Fifteen mg/kg of bifemelane significantly increased the concentrations of glucose, 14C-acid soluble fraction and the synthesis of acetylcholine from [U-14C] glucose. In the in vitro experiments, cholinesterase activity was significantly inhibited by the bifemelane (1.47 microM). However, its inhibitory effects were about 1/9000 of physostigmine sulfate, which might be too weak to increase the acetylcholine concentration in the brain.(ABSTRACT TRUNCATED AT 250 WORDS)

[Pharmacological studies on sufoxazine (Y-8894). (II). Anti-anoxic effect]

The anti-anoxic effect of sufoxazine was investigated in various cerebral anoxia models with mice, in comparison with those of various cerebroactive drugs. Sufoxazine reduced dose-dependently the duration of coma induced by a sublethal dose of KCN (1.8 mg/kg, i.v.), significantly stimulating recovery from the coma at 5 mg/kg, i.p. and 30 mg/kg, p.o. It also protected against a lethal dose of KCN (2.5 mg/kg, i.v.). Sufoxazine prolonged the survival time of mice subjected to hypobaric and normobaric hypoxia. Dihydroergotoxin and ifenprodil gave similar protection in the KCN-induced anoxia models, but produced adverse effects in the hypoxia models. Calcium hopantenate exerted similar but weak protection only at a dose as high as 300 mg/kg, i.p. These findings suggest that sufoxazine has an anti-anoxic action superior to those of the other cerebroactive drugs used.

Fatal poisoning by 1,1,1-trichloroethane after prolonged survival

A fatal case of 1,1,1-trichloroethane (methyl chloroform) poisoning, in which the patient survived, without recovering consciousness, for more than 3 years, is described. The brain showed symmetrical infarction of the lenticular nuclei and of the occipital cortex, changes which may have been the cause of neurological manifestations during life. The pattern of cerebral hypoxia was similar to, but not identical with that found in carbon monoxide poisoning, and might be specific for 1,1,1-trichloroethane poisoning.

[EEG in the prognosis of toxic coma: reflections apropos of unusual data]

During acute intoxications, the first EEG may show persistence or abolition of cerebral activity, but the possibility of recovery after isoelectric tracing in toxic comas must be emphasized. EEG patterns frequently suggest the probability of hypnotic tranquilizer poisoning; 4 types of EEG are encountered corresponding to different grades of toxic coma. Recurrent periods of electrical silence alternating with bursts of activity are habitually recorded in carus comas with hypothermia due to acute barbiturate intoxication, with good prognosis. The possibility of a neurological disturbance associated with drug overdose must be raised whenever an asymmetric tracing is encountered. Serial recordings may detect complications such as: a localized lesion, anoxia or, very rarely, typical paroxysmal abnormalities reappearing in comitial patients before emergence from a toxic coma. Paradoxical monomorphic delta activity corresponding to improvement must not be considered as an aggravation. Peculiar EEG findings occur after oral trichlorethylene poisoning, with temporary clinical deterioration and intermittent periods of electrical silence; recovery is possible. An alpha-like pattern after cardiac arrest of toxic origin has a poor prognosis. The appearance of alternating patterns suggests the development of irreversible brain damage.

[Thiopental for the prevention of severe brain damage after carbon monoxide poisoning. Case report on 3 cases]

Three cases of severe carbon monoxide poisoning are described presenting with deep coma, generalised extensor spasms and myoclonia as symptoms of acute midbrain syndrome. Despite this poor prognosis all patients survived without essential neurological impairment. This favourable outcome is thought to be due to the administration of thiopentone for the amelioration of hypoxic brain damage in dosages commonly employed in anaesthesia.

Cerebral hypoxia from bicarbonate infusion in diabetic acidosis

To study the delivery of oxygen to the cerebral tissue during metabolic acidosis and its therapy with bicarbonate (NaHCO3), oxygen partial pressure of the cisternal fluid was measured in 12 experiments of HCl-induced acidemia and eight experiments of diabetic ketoacidosis in 16 unanesthetized dogs. Full correction of acidosis with bicarbonate caused a significant (P less than 0.05) decrease in Pcsf 2: in the HCl acidotic dogs, Pcsfo2 decreased from 53.9 +/- 2.2 torr to 45.9 +/- 2.3 torr within one hour; in the ketoacidotic dogs, Pcsfo2 decreased for 48.5 +/- 5.4 torr to 26.7 +/- 6.6 torr within six hours. In the ketoacidotic dogs not treated with bicarbonate, there was no significant change in Pcsfo2. An inverse relationship (P less than 0.01) between the cisternal lactic acid level and the cisternal PO2 was also observed. It is concluded that NaHCO3 therapy in diabetic ketoacidosis decreases the cerebral O2 availability and that cerebral hypoxia contributes to the brain dysfunction encountered after the initiation of such therapy in acidemia.