Diphenylhydantoin induces apoptotic cell death of cultured rat cerebellar granule neurons

Apoptosis is one form of physiological or programmed cell death responsible for the selective elimination of various cell types during development. We have observed and characterized a delayed-type of neurotoxicity induced in cultured cerebellar granule neurons by diphenylhydantoin. Diphenylhydantoin toxicity of cerebellar granule neurons is time and concentration dependent. Morphological studies using Nomarski optics and staining with the fluorescent dye Hoechst 33258 demonstrate that diphenylhydantoin-induced neurotoxicity of cerebellar granule neurons is associated with cytoplasmic blebbing, heterochromatic clumping and condensation of chromatin that precede cell death. Unlike glutamate toxicity (excitotoxicity) diphenylhydantoin-induced neurotoxicity of cerebellar granule neurons is attenuated by actinomycin D and cycloheximide, and is associated with nucleosomal size DNA fragmentation. Since we have previously reported that depolarization of cultured cerebellar granule neurons with high concentrations of K+ promotes the survival of these neurons by blocking apoptosis, we examined the effects of diphenylhydantoin on the K(+)-evoked increase in intracellular calcium. Using microfluorimetry and fura-2 to measure intracellular calcium we found that neurotoxic concentrations of diphenylhydantoin markedly reduce the increase in intracellular calcium associated with elevated extracellular potassium. Taken together, these data demonstrate that exposure of cultured cerebellar granule neurons to pharmacologically relevant concentrations of diphenylhydantoin results in a delayed type of neurotoxicity characterized by the biochemical and morphological features of apoptosis.

Activation of muscarinic cholinergic receptors blocks apoptosis of cultured cerebellar granule neurons

We have recently reported that the majority of cultured rat cerebellar granule neurons undergo apoptosis when maintained in the presence of physiological concentrations of K+ (nondepolarizing conditions). We now report that exposure of cultured cerebellar granule neurons, maintained under nondepolarizing conditions, to the muscarinic cholinergic receptor (mAchR) agonists carbachol and muscarine results in a concentration- and time-dependent inhibition of apoptosis. The nicotinic cholinergic receptor agonist (-)-nicotine fails to mimic, and the nicotinic cholinergic receptor antagonist dihydro-beta-erythroidine fails to antagonize, the survival-promoting effects of carbachol. In contrast, relatively low concentrations of atropine completely prevent the effects of carbachol in blocking apoptotic death of cultured granule neurons. Although the m1- and m2-preferring mAchR antagonists pirenzepine and gallamine, respectively, fail to reverse the effects of carbachol, the m3-preferring antagonist 4-diphenylacetoxyl-N- methylpiperidine methiodide completely blocks the survival-promoting effects of carbachol. These data demonstrate that activation of the mAchR (possibly of the m3 subtype) blocks apoptosis of cultured cerebellar granule neurons. The antiapoptotic effects of mAchR agonists are not indirectly mediated via glutamate release from granule neurons, because antagonists of either N-methyl-D-aspartate or non-N-methyl-D-aspartate glutamate receptors fail to affect the antiapoptotic effects of carbachol or muscarine. Moreover, exposure of cultured cerebellar granule neurons to antiapoptotic concentrations of carbachol, in contrast to high concentrations of K+ or glutamate receptor agonists, results in only a small and transient elevation of the intracellular Ca2+ concentration, as measured by fura-2 microfluorimetry. Slow neurotransmitters such as acetylcholine, acting via their cognate G protein-coupled receptors, may prevent neuronal apoptosis in the developing (and perhaps adult) central nervous system.

Steroid potentiation and inhibition of N-methyl-D-aspartate receptor-mediated intracellular Ca++ responses: structure-activity studies

Pregnenolone sulfate and 15 related steroids were investigated for their effects on N-methyl-D-aspartate (NMDA)-induced elevations in intracellular Ca++ ([Ca++]i) in cultured rat hippocampal neurons by microspectrofluorimetry with the Ca(++)-sensitive indicator fura-2. Several pregn-5-ene steroids markedly potentiated NMDA-mediated [Ca++]i responses. Pregnenolone sulfate and its 21-acetoxy derivative and pregnenolone hemisuccinate were the most active. At a concentration of 50 microM, each produced approximately 300% potentiation of 5 microM NMDA responses. In addition, several steroids were identified that inhibited NMDA-induced elevations in [Ca++]i, the most potent of which was 3 alpha-hydroxy-5 beta-pregnan-20-one sulfate (IC50, 37 microM). Concentration-response curves for NMDA in the presence of active steroids revealed noncompetitive interaction(s) of these steroids with the NMDA receptor. Although the mechanism(s) responsible for either steroid-induced augmentation or inhibition of NMDA-receptor responses is unknown, these data suggest the presence of one or more steroid recognition sites with a high degree of structural specificity associated with NMDA receptors. These results further raise the possibility that pregn-5-ene 3-sulfates and pregnane 3-sulfates could be endogenous modulators of NMDA receptor-mediated synaptic events.

Restoration of dopamine overflow and clearance from the 6-hydroxydopamine lesioned rat striatum reinnervated by fetal mesencephalic grafts

The purpose of these experiments was to investigate the electrochemical indices of mesencephalic dopaminergic grafts as they function in the rat striatum. Sprague-Dawley rats were injected unilaterally with 6-hydroxydopamine into the medial forebrain bundle, and the effectiveness of these lesions was tested by measuring apomorphine-induced rotation. The unilaterally lesioned rats were later transplanted with fetal ventral mesencephalon. Only animals receiving ventral mesencephalon transplants showed significant decreases in rotation after grafting. High-speed chronoamperometric recording techniques using Nation-coated carbon fiber electrodes were used to evaluate dopamine (DA) overflow in the striatum of urethane-anesthetized rats. We found that 6-hydroxydopamine lesions resulted in a loss of KCl-induced DA overflow and clearance. Ventral mesencephalon grafts restored neurochemical indices. The zone of normalized DA clearance was considerably larger than that of normalized release. Furthermore, histochemical studies using tyrosine hydroxylase immunoreactivity confirmed graft survival and neurite outgrowth from the graft into the lesioned striatum. In conclusion, these findings suggest that the behavioral improvements by grafts of fetal mesencephalic tissue are accompanied by morphological and electrochemical evidence of reinnervation and the restoration of DA input. Measurement of DA clearance may reveal a wider area of reinnervation than that indicated by more traditional immunocytochemical methods.

A simple method for diagnosing traumatic occlusion of the vertebral artery at the craniovertebral junction

STUDY DESIGN

A simple method, thin-slice contrast-enhanced computed tomographic (CT) scan, was evaluated as a first-line rapid screening procedure for diagnosing traumatic occlusion of the vertebral artery at the craniovertebral junction.

OBJECTIVES

This procedure was performed in patients suffering from injuries of the high cervical spine or the craniovertebral junction. Vertebral angiography was undertaken after this procedure to confirm the diagnosis.

SUMMARY OF BACKGROUND DATA

Well-enhanced vertebral arteries can be demonstrated clearly in normal subjects by using this method. Occlusion of the vertebral artery produces delayed contrast enhancement of the proximal artery and abrupt interruption of its course.

METHODS

Thin-slice CT scan was performed from the atlas to the occipital condyles after an intravenous injection of angiograffin. The plane of the CT scan was aligned in a parallel manner to the upper margin of the atlas. The CT scanning was repeated until the contrast enhancement of the vertebral arteries became faint.

RESULTS

Occlusion of the unilateral vertebral artery was successfully diagnosed in a patient with Jefferson's fracture by using the present technique. A subsequent vertebral angiography confirmed the diagnosis.

CONCLUSIONS

The present technique should be performed as a routine screening procedure in patients suffering from injuries to the craniovertebral junction.

N-methyl-D-aspartate induces a rapid, reversible, and calcium-dependent intracellular acidosis in cultured fetal rat hippocampal neurons

The ability of NMDA to alter intracellular pH (pHi) was studied in fetal rat hippocampal neurons and glia using the pH-sensitive fluorescent indicator 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF). Brief exposure (60 sec) of hippocampal neurons to NMDA (2.5-250 microM) results in a rapid, and in most cells reversible, reduction in pHi, with full recovery to baseline pHi values taking several minutes following removal of NMDA. In contrast, little or no change in pHi was observed in glial cells exposed to these same concentrations of NMDA. The NMDA-induced acidification of neurons was concentration and time dependent, with an EC50 of 39 microM and Emax (delta pH) of -0.53. More prolonged exposure to NMDA (> or = 10 min) resulted in a more prolonged reduction in pHi values over the ensuing 20 min observation period. The intracellular acidification resulting from NMDA exposure of hippocampal neurons was blocked by the NMDA receptor antagonist 3-((+/-)-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP). Moreover, removal of extracellular Ca2+ eliminated both the selective NMDA-induced elevation in [Ca2+]i and the reduction in pHi, indicating that Ca2+ influx may be required for the decrease in pHi induced by NMDA receptor activation. Finally, the NMDA-induced reduction in pHi was not significantly attenuated when extracellular [H+] was decreased by increasing extracellular pH to 8.0. The latter suggests that an intracellular source of H+ is responsible for the NMDA-induced reduction in neuronal pHi. The reduction in neuronal pHi induced by NMDA receptor activation may mediate some of the physiological and (or) pathophysiological actions of glutamate.

Combined treatment with nicardipine, phenobarbital, and methylprednisolone ameliorates vasogenic brain edema

Free radicals formed around the edematous areas of the brain can cause lipoperoxidation of the cellular membrane, followed by calcium influx into the cell through calcium channels. These secondary insults may aggravate vasogenic brain edema. Since phenobarbital is a free radical scavenger, methylprednisolone has an antilipoperoxidation effect; and nicardipine is a calcium channel blocker, we hypothesized that combined treatment with phenobarbital, methylprednisolone, and nicardipine would be beneficial in vasogenic brain edema. This hypothesis was tested in Sprague-Dawley rats with a transdural cold-injury on the right parietal cortex. The animals were randomly divided into two groups. Animals in the treatment group were injected intraperitoneally with phenobarbital (4 mg/kg), methylprednisolone (50 mg/kg), and nicardipine (10 micrograms/kg) at 5 min and 8 hours after the cold-injury. The control animals were injected with saline. These animals were sacrificed 24 hours after the injury. The extent of brain edema was assessed by measuring the water content, the inulin distribution volume, and the distribution area of Evans blue in the brain. Our results showed that the water content of the edematous hemisphere was similar in the control and the treatment groups. However, Evans blue distribution area and inulin distribution volume of the treatment group were less than those of the control group by 12% and 31%, respectively. In conclusion, the combined treatment with phenobarbital, methylprednisolone and nicardipine is beneficial in vasogenic brain edema.

Cerebral glucose utilization and blood flow in adult spontaneously hypertensive rats

Not only blood pressure but also behavioral activity, brain morphology, and cerebral ventricular size differ between young spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. This suggests that cerebral blood flow and cerebral metabolism may vary between these two rat strains. To test this hypothesis, we measured local cerebral glucose utilization in 31 brain areas of 26-30-week-old rats. Local cerebral blood flow was also assessed in these same areas. Cerebral glucose utilization was measured by the 2-deoxyglucose method; cerebral blood flow was determined by the iodoantipyrene method. In virtually all gray matter structures, the apparent rate of glucose utilization was lower in SHR than in normotensive WKY rats; the interstrain differences varied significantly among structures and were statistically significant (uncorrected t tests) in 14 of 28 gray matter areas. Local cerebral blood flow was fairly similar in the two rat strains. The coupling of blood flow to glucose utilization varied significantly among brain areas in normotensive WKY rats as well as in SHR. In a number of gray matter structures, the coupling of flow to metabolism differed between hypertensive and normotensive animals. These data suggest that for many brain areas, either glucose utilization or glucose partitioning differs between WKY rats and SHR.

Differences and similarities in albumin and red blood cell flows through cerebral microvessels

The hypothesis that microvessels in brain parenchyma are continuously perfused by plasma but intermittently perfused by red blood cells (RBCs) was tested in awake Sprague-Dawley rats. The microvascular distribution volumes of radioiodinated serum albumin (RISA) and 51Cr- and 55Fe-labeled RBCs were measured for periods from 15 s to 30 min. Local cerebral blood flow (LCBF) was assessed by the iodoantipyrine technique. The RISA and RBC distribution volumes were constant in the 12 areas studied from 15 s onward. These data fit a model of continuous plasma flow with intermittent RBC flow (and thus support the hypothesis), but they are also consistent with other models, e.g., continuous flow of both plasma and RBCs through all perfused microvessels. In parallel with LCBF, microvascular blood volume varied greater than 10-fold among brain areas. Relative to arterial hematocrit, microvascular hematocrits were low, which indicates that the passage of RBCs through parenchymal microvessels is more rapid than that of RISA. This could be the result of both the Fahraeus effect and intermittent RBC flow.

Cerebral ischemia is the main cause for the onset of heat stroke syndrome in rabbits

During the onset of heat stroke, rabbits displayed hyperthermia (42.8 degrees C), and decreased cerebral perfusion pressure and decreased cerebral blood flow (as reflected by a prolonged cerebral circulation time) compared to those of normothermic rabbits. On the other hand febrile rabbits, during the fever plateau did not show the above responses, although they had a similar level of hyperthermia (42.4 degrees C). The data support the concept that cerebral ischemia is the main cause for the onset of the heat stroke syndrome.

[Effects of caffeine on shuttle, operating behaviors, and brain metabolism in rats]

Effects of caffeine (30, 60, and 120 mg.kg-1, ip) on shuttling and operating behaviors in 80 rats were studied. Effects of caffeine (60, 120 mg.kg-1, ip) on contents of dinucleotides and pterins in 6 brain areas of 18 rats were investigated by HPLC with fluorescent detector. The results showed that the dose of caffeine that induced augment of shuttle behavior was lower than that induced operating behavior. Caffeine 120 mg.kg-1 inhibited both shuttling and operating behavior, decreased FAD content in caudate nucleus; caffeine 60 mg.kg-1 increased FAD in cerebellum and brain stem. Caffeine 60, 120 mg.kg-1 increased brain NADH contents, decreased pterin contents, and increased biopterin contents in some brain areas.

Functional variations in parenchymal microvascular systems within the brain

Variations in microvascular system functions were observed among a number of brain areas. The rates of local blood flow varied 18-fold among areas and were extremely high in neuroendocrine structures. Marked differences in blood flow were also found within some brain structures. The volume of radiolabeled blood in perfused parenchymal microvessels ranged from 5 to 70 microliters/g and correlated closely with local cerebral blood flow. The hematocrits within parenchymal microvessels were 45-75% of the arterial hematocrit, which indicates that red cells more rapidly traverse brain microvessels than do plasma proteins. The mean transit times of blood through parenchymal microvessels were extremely short and ranged from 0.3 to 0.6 s.

The effects of chronic serum sickness on albumin distribution and glucose utilization in rat brain

The level of cerebrospinal fluid (CSF) protein is elevated in diseases and disease models that are associated with circulating immune complexes such as serum sickness. Circulatory immune complexes are known to deposit in the basal lamina of fenestrated capillaries and may, as a result, affect both capillary bed and parenchymal function. Since the brain has both fenestrated and unfenestrated capillaries and immune complexes deposit to a varying extent in the fenestrated capillaries in chronic serum sickness, cerebral capillary permeability to protein may be altered in some brain areas and lead to the elevation of CSF proteins. In addition various other cerebrovascular and metabolic functions may also be affected by this condition. In this study either radio-iodinated serum albumin (RISA) or 2-[14C]deoxyglucose (14C-2DG) was intravenously injected into control Wistar rats and Wistar rats with chronic serum sickness; subsequently the tissue levels of radioactivity were measured by quantitative autoradiography in 4 brain areas with fenestrated capillaries and 11 brain areas with unfenestrated capillaries. The 2-min distribution of RISA, which demarcates the volume of circulating plasma in perfused microvessels and is generally proportional to local plasma flow, was the same in control and experimental rats. The passage of RISA from blood into brain over 30 min was negligible in both groups; thus cerebral capillary permeability to albumin was not detectably increased in any of these 15 brain areas by chronic serum sickness. The rate of local cerebral glucose utilization, an indicator of local metabolic and neural activity, was calculated from the 14C-2DG data and was virtually identical in control and experimental rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of amobarbital on pterins and dinucleotides contents in rat brain

The effects of amobarbital (50 mg.kg-1 ip) on the brain concentrations of biopterin, pterin, reduced nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) were studied by a reverse phase high performance liquid chromatography with fluorescent detector. Amobarbital increased FAD concentrations in 5 brain areas and pterin concentration in the cortex, but decreased biopterin concentrations in the cortex and hippocampus.

Quantitative autoradiographic assessment of 55Fe-RBC distribution in rat brain

A simple in vivo technique of labeling erythrocytes (RBCs) with 55Fe was developed for quantitative autoradiography (QAR). This procedure involved injecting 5-6 ml of [55Fe]ferrous citrate solution (1 mCi/ml) intraperitoneally into donor rats. The number of labeled RBCs reached a maximum at around 7 days and declined very slowly thereafter. Labeled RBCs were harvested from donor rats and used for RBC volume measurement in awake rats. Brain radioactivity was assayed by QAR, which yielded spatial resolution of greater than 50 microns. Tight nearly irreversible binding of 55Fe to RBCs was found in vivo and in vitro. More than 99.5% of the 55Fe in the blood of donor rats was bound to RBCs. Because of this, labeled blood can be taken from donors and injected into recipients without further preparation. The tissue absorption of 55Fe emissions was the same in gray and white matter. Microvascular RBC volumes measured with 55Fe-labeled RBCs agreed with those assayed with 51Cr-labeled RBCs for many, but not all, brain areas. In conclusion, 55Fe-RBCs can be readily prepared by this technique and accurately quantitated in brain tissue by QAR.

Cerebral capillary bed structure of normotensive and chronically hypertensive rats

In this study cerebral capillary bed structure and the effects of chronic hypertension on these systems have been assessed in 6- to 7-month-old spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats. Capillary diameter (D), profile frequency (Na), volume fraction (Vv), and surface area (Sv) were quantitated by light microscopic morphometry of eight brain areas including the sensorimotor cortex and subfornical organ. Previously presented data from normotensive Sprague-Dawley rats (SpD) of similar age were also compared. Within each of the three rat strains, D, Na, Vv, and Sv varied among brain areas. For the sensorimotor cortex and subfornical organ, capillary profile frequency differed significantly among the three rat strains. In SHR and WKY, there was an inverse correlation between profile frequency and diameter, i.e., as Na increased among brain areas, D decreased. In six brain areas capillary volume fraction and surface area were identical in SHR and WKY, but were lower in SpD. Consistent differences between SHR and WKY were found only for the subfornical organ, which suggests some involvement of this structure in hypertension. Since there were few statistically significant differences between SHR and WKY and many statistically significant differences between the two normotensive strains, cerebral capillary bed structure seems to be independent of arterial blood pressure in most brain areas of these rats.

Two-way shuttlebox avoidance conditioning and brain NADH in rats

The effects of amphetamine (1.5 mg/kg) and caffeine (120 mg/kg, 75 mg/kg) on shuttle behavior and on the concentrations of reduced nicotinamide adenine dinucleotide (NADH) of the brain were studied in 56 rats from the perspective of regional brain metabolism. Amphetamine potentiated the shuttle behavior including avoidance responses and response speed, while it increased NADH concentrations in the hippocampus. The low dose of caffeine increased avoidance responses. The high dose of caffeine inhibited avoidance responses, but it had no effect on NADH concentrations in discrete brain regions.

Microlaryngoscopic surgery. An analysis of 300 cases

Microlaryngoscopic operations were performed on 300 cases of very small lesions of the vocal cord from October 1985 to December 1987 under high frequency ventilation (HFV) and compound venous anaesthesia. 233 cases were followed up for at least 1 month after operation. Among them, 91% recovered completely or improved significantly. The indications, contraindications, anaesthesia, surgical procedures, complications, results, merits and disadvantages of the microlaryngoscopic surgery were discussed in detail.

High-field nuclear magnetic resonance techniques for the investigation of a beta-cyclodextrin:indomethacin inclusion complex

The inclusion complex of indomethacin sodium salt in beta-cyclodextrin has been studied by proton NMR at high magnetic field. The continuous variation technique was used to evidence the formation of a soluble 1:1 complex in aqueous solution at physiological pH. The effective association constant was determined by the Benesi-Hildebrand procedure to be 760 M-1 at 303 K. This technique requires NMR measurements in the presence of a very large excess of one of the complex components and, since both beta-cyclodextrin and the sodium salt of indomethacin are sparingly soluble in water, NMR spectrometers operating at very high magnetic fields were used. Besides the effective association constant, the Benesi-Hildebrand approach allows a precise determination of all NMR parameters of the pure inclusion complex which may be used for a complete analysis of the geometry of this complex in solution.

Annular pancreas. Etiology, classification and diagnostic imaging

A rare type of annular pancreas, in which the tail of the annular duct is fused with the dorsal pancreatic duct to form the main duct, and its diagnostic imagings of endoscopic retrograde cholangiopancreatography, hypotonic duodenography, computed tomography and ultrasound are described. Annular pancreas is an anomaly embryologically formed by the ventral anlage of the pancreas as the duodenum rotates, mainly due to hypertrophy of the left ventral bud. According to the fusion pattern of the ventral and dorsal pancreatic ducts, annular pancreas can be divided into three types: type I, divisional annular pancreas; type II, branch annular pancreas; and type III, main duct annular pancreas. Endoscopic retrograde cholangiopancreatography, hypotonic duodenography, computed tomography and ultrasound can show the imagings of annular pancreas from different aspects, but the final diagnosis must be based on the evidence of endoscopic retrograde cholangiopancreatography or hypotonic duodenography combined with computed tomography or ultrasound.

Effect of glucagon on the motility of esophageal smooth muscle

The functions of glucagon were studied experimentally and clinically. It was found that glucagon (2 x 10(-6)g/ml) could not induce any demonstrable changes in the longitudinal contraction and tonicity of the isolated muscle of the lower esophageal body in 4 rats, nor could cause (0.2 mg iv) significant changes in swallow motility of the esophagus and lower esophageal sphincter (LES) (the esophageal barium transit time, the largest esophageal caliber, the angle of esophageal contraction, the largest LES caliber, and the amount of barium retention at LES) in 6 volunteers under serial-radiography but it (0.2 mg iv) could cause hypomotility of the stomach and duodenum in 19 volunteers. No obvious side-effects were found in 20 volunteers. The recent experimental evidences have suggested that the inhibitory effect of glucagon on the motility of the smooth muscle of the alimentary tract may not be due to its direct action on the receptor, but to its interference with intramural cholinergic neuronal transmission.

Long-term follow-up of 344 Shanghai psoriatics

344 patients with psoriasis vulgaris treated in Huashan Hospital, Shanghai were followed up for 7-30 years. 13% of them developed arthralgia and 2% had joint deformities. One patient developed erythroderma due to dexamethasone medication. Internal malignancy occurred in 2 patients (0.58%). The severity of the course of the disease was neither influenced by family history nor alcoholism, but was markedly influenced by the duration of illness and administration of anti-neoplastic drugs.

Measurement of basilar artery diameter in dogs: CT evaluation correlated with arteriography

In this study we have used a computed tomographic (CT) method using profile analysis to measure the diameter of the basilar artery. In a search for a noninvasive and repeatable method to substitute for the traditional arteriography in the evaluation of the degree of cerebral vasospasm, we employed both CT and arteriography to measure the diameter of the basilar artery in eight adult mongrel dogs weighing between 7 and 12 kg. In three of these animals, assessments were made before and after subarachnoid hemorrhage (SAH) induced by injecting autologous arterial blood into the cistern magna. It was found that the basilar artery diameter as evaluated by CT was 47% larger than that measured by arteriography. However, there was a very good correlation (n = 63, r = 0.75, p less than 0.001) between the two methods. This paper presents a new model for the measurement of the basilar artery diameter, one which may also provide a safer method for the evaluation of vasospasm in humans.