Does ischemia with reperfusion lead to oxidative damage to proteins in the brain?

Recent results suggest that even relatively brief periods of ischemia in gerbils (10 min) lead to oxidative damage to brain proteins, reflected in an increased carbonyl content in the soluble protein fraction and a decreased glutamine synthetase (GS) activity. Since we failed to reproduce these findings in rats subjected to 15 min of transient ischemia, we explored whether oxidative damage to proteins could be observed after longer ischemic periods. To that end, one middle cerebral artery was occluded in rats for either 1 or 3 h, with recirculation periods of 0 min, 15 min, 1 h, and 6 h. Protein carbonyl content and GS activity were determined in focal and perifocal tissues and compared with values obtained in the same areas on the contralateral side. Ischemia, particularly of 3-h duration, followed by various reperfusion periods was accompanied by a significant (16-35%) decrease in the concentration of proteins of the soluble protein fraction. However, in no group was there an increased carbonyl content of the remaining proteins in this fraction. When expressed per milligram of protein, GS activity remained unchanged or rose somewhat. An inconsistent (and moderate) decrease in GS activity was present only if GS activity was expressed per milligram of wet tissue. The present findings, which fail to document oxidative damage to proteins following focal ischemia of 1- or 3-h duration, are thus radically different from those obtained in gerbils. The results suggest that appreciable species differences exist and raise the question of whether free radical-mediated oxidation of proteins is an invariable component of ischemic brain damage.

Novel, potent, and orally active substance P antagonists: synthesis and antagonist activity of N-benzylcarboxamide derivatives of pyrido[3,4-b]pyridine.

A series of 4-phenylisoquinolone derivatives were synthesized and evaluated for NK1 (substance P) antagonist activity. Highly potent antagonists, 4-phenyl-3-isoquinolone-N-benzylcarboxamides (11), were discovered from the structure-activity relationship studies on the isoquinolone-urea lead 1a. Optimization of the activity in this series resulted in the development of 5-phenyl-6-pyrido[3,4-b]pyridine-N-benzylcarboxamides (30) which are highly potent orally active NK1 antagonists. Among the compounds synthesized, N-[3,5-bis(trifluoromethyl)benzyl]-7,8-dihydro-N,7-dimethyl-8-oxo-5- (substituted phenyl)-6-pyrido[3,4-b]pyridinecarboxamides (30a,f,g) showed excellent antagonist activities with IC50 values (in vitro inhibition of [125I]-BH-SP binding in human IM-9 cells) of 0.21-0.34 nM and ED50 values (in vivo inhibition of capsaicin-induced plasma extravasation in guinea-pig trachea, iv) of 0.017-0.030 mg/kg. These compounds exhibited significantly potent activity upon oral administration with ED50 values of 0.068-0.17 mg/kg. Conformational studies on 30g indicated that the two stable conformers of 30g are quite similar to those of CP-99,994.

Relationship of milk intake and vitamin K supplementation to vitamin K status in newborns.

Vitamin K status was evaluated by measuring blood acarboxyprothrombin (PIVKA-II) levels on the fifth day of life. The incidence of PIVKA-II-positive infants was higher in breast-fed babies than in those given supplementary (mixed) feeding. The median of total amount of milk intake during the first 3 days was significantly lower in PIVKA-II-positive infants than in PIVKA-II-negative infants among infants given both types of feedings. In addition, there was a significant negative correlation between a positive PIVKA-II proportion and the amount of milk intake in the breast-fed babies. The minimum dose of vitamin K2 necessary to prevent a positive PIVKA-II reading was 15 micrograms among babies with a normal absorption potential.

In vitro closing behavior of the St. Jude Medical heart valve in the pulmonary position. Valve incompetence originating in the prosthesis itself.

We examined the in vitro closing behavior of the St. Jude Medical heart valve, simulating (1) a low-pressure system, (2) the anatomic peculiarity of the right ventricular outflow tract and the main pulmonary artery, and (3) disturbed diastolic compliance of the right ventricle. The variables in the experiment were the load impedance to the pump and the valve orientation. The results were as follows. The sequence of closure of the two semidiscs was based on the valve orientation; reduction in impedance caused the semidisc that closed last to remain open, while the other semidisc continued its open-close motion; further reduction in impedance prevented the semidisc, which continued its open-close motion, from closing completely. These results highlight the forces involved in semidisc closure and the existence of a threshold of force for completion of semidisc closure. Further, the results demonstrate that under certain circumstances the threshold cannot be exceeded via those forces. Therefore this incompetence must originate in the prosthesis itself. In this regard, we suggest an urgent need to reconsider the indications for St. Jude Medical heart valve pulmonic implantation. Finally, we advocate the necessity for an in vitro assessment of valve prostheses in a low-pressure system, to evaluate the safety of right-sided placement.

Successful surgical repair of truncus arteriosus with interrupted aortic arch in infancy by an anterior approach.

A 98-day-old infant was successfully operated on for truncus arteriosus (type I) with interrupted aortic arch (type B) using a one-stage anterior approach. The interrupted aortic arch was reconstructed by direct anastomosis between the ascending and descending aorta. The ventricular septal defect was closed, and a 12-mm porcine valved conduit was placed on the right side of the ascending aorta to establish continuity between the right ventricle and pulmonary artery. Surgical procedures for the repair of this malformation are the focus of discussion.

Relationship between brain damage and memory impairment in rats exposed to transient forebrain ischemia.

The relationship between changes in learning behavior and neurological damage following transient forebrain ischemia was studied in rats. The transient forebrain ischemia was induced by 4-vessel occlusion, and behavioral experiments were started 4 weeks later when histological damage to the brain seemed to have stabilized. Histological evaluation of brain damage was conducted after completion of the behavioral studies. The rats showed marked learning impairment in a radial maze task done from 4 to 10 weeks after ischemia. In particular, there was an increase in the number of working memory errors according to the duration of forebrain ischemia. However, the same rats showed good avoidance responses in a passive avoidance task done 12 weeks after ischemia. The rats also showed good acquisition of escape response in a water maze task carried out 13 weeks after ischemia, but showed slight impairment of spatial navigation in the transfer test. Marked neuronal degeneration was observed in the hippocampal pyramidal cells of the rats exposed to ischemia. This neuronal damage was closely related to memory impairment in the radial maze task, as demonstrated by a significant negative correlation (r = -0.609 or -0.709) between the number of surviving neurons and the number of reference or working memory errors. These results suggest that rats exposed to transient forebrain ischemia show marked impairment of both reference and working memories as a result of postischemic hippocampal damage.

Increase in basic fibroblast growth factor-like immunoreactivity in rat brain after forebrain ischemia.

Using immunohistochemical techniques, a study was conducted to determine whether basic fibroblast growth factor (bFGF) is generated as one of the 'self-repair' responses in rat brain following transient forebrain ischemia. In normal brain, slight bFGF-like immunoreactivity was observed. However, in rats exposed to 20 min of forebrain ischemia, intense bFGF-like immunoreactivity was observed in the CA1 subfield of the hippocampus and the caudate putamen, and marked activity was evident in the temporal cortex, corpus callosum and the CA4 subfield of the hippocampus. Marked neuronal degeneration was also observed in these brain regions following forebrain ischemia. These results suggest that induction of bFGF-like immunoreactivity may be related to the healing which follows brain ischemia.

Proto-oncogene c-fos is transiently induced in the rat cerebral cortex after forebrain ischemia.

The amounts of mRNAs for proto-oncogene c-fos and structural protein beta-actin were measured in the rat cerebral cortex after transient forebrain ischemia. A transient and specific induction of c-fos mRNA was noticed in the cerebral cortex 30-90 min after ischemia followed by decline to control value. In contrast, the level of mRNA for beta-actin was not altered throughout the recirculation period examined. These results suggest specific role of c-fos gene after brain damage.

Beneficial effect of CV-4151 (Isbogrel), a thromboxane A2 synthase inhibitor, in a rat middle cerebral artery thrombosis model.

Effects of thromboxane A2 (TXA2) synthase inhibitors (CV-4151 and ozagrel) on cerebral thrombosis and cerebral damage were examined in a rat middle cerebral artery (MCA) thrombosis model and their potencies were compared with the conventional antithrombotic agents, aspirin and ticlopidine. CV-4151 significantly inhibited photochemically induced MCA thrombosis by oral (1 and 10 mg/kg) and intravenous (1 mg/kg) administration. Ozagrel (10 mg/kg, p.o.) also inhibited it. The potency of CV-4151 was about 10 times stronger than that of ozagrel, being comparable with the inhibition of blood TXA2 generation. Aspirin (100 mg/kg, p.o.) and ticlopidine (300 mg/kg, p.o.) showed an inhibitory tendency on MCA thrombosis. Twenty-four h after photochemical stimulation, cerebral edema and cerebral infarction were observed, and the lactate content in the brain increased. CV-4151 and ozagrel prevented this edema, and the antiedema effects of the drugs were correlated with the antithrombotic effect on thrombotic MCA occlusion. CV-4151 (10 mg/kg, p.o.), furthermore, significantly reduced the infarct size and inhibited the increase in lactate content. These results indicate that TXA2 synthase inhibitors inhibit cerebral damage by inhibition of MCA occlusion with thrombosis, probably resulting from the inhibition of TXA2 generation, and their effects are superior to those of aspirin and ticlopidine. TXA2 might play an important role in cerebral damage in the MCA thrombosis model. CV-4151 might be a useful drug for the treatment of cerebral thrombosis and for the prevention of cerebral infarction.

Senescence-accelerated mouse (SAM): age-related reduced anxiety-like behavior in the SAM-P/8 strain.

Age-related behavioral changes in the passive avoidance, food neophobia, elevated plus-maze, and water-lick conflict tests were studied using substrains of senescence-accelerated mouse (SAM-P/8 and SAM-R/1) at 2 to 20 months of age. SAM-P/8 mice exhibited a significant impairment of acquisition of passive avoidance compared with SAM-R/1 mice when they were trained repeatedly, and the acquired response in SAM-P/8 mice rapidly diminished in contrast to good retention in SAM-R/1 mice. SAM-P/8 mice showed an age-related decrease in the latency to eat novel food after a 24-h food deprivation as compared with SAM-R/1 mice at 2 to 12 months of age, despite no significant difference in latency to eat familiar food between the two strains. In the elevated plus-maze test, SAM-P/8 mice had apparent increases in the number of entries into open arms and time spent on open arms in comparison to SAM-R/1 mice at 4 through 12 months of age; this difference became obvious with aging, implying age-associated reduced anxiety in the SAM-P/8 strain. In addition, SAM-P/8 mice exhibited a significant increase in punished water drinking compared to SAM-R/1 mice in the water-lick conflict test, although unpunished water intake in SAM-P/8 mice did not differ from that in the SAM-R/1 control. Aged SAM-R/1 mice, 20 months old, exhibited low anxiety-like behavior in the food neophobia and elevated plus-maze tests such as was seen in SAM-P/8 mice, when compared with young (4-month-old) SAM-R/1 mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Age-related changes in learning and memory in the senescence-accelerated mouse (SAM).

Age-related changes in learning ability were studied in senescence-accelerated mice (SAM) reared under specific pathogen-free (SPF) conditions. SAM-P/8/Ta (SAM-P/8, senescence-prone substrain) showed an age-associated increase in spontaneous motor activity (SMA) compared with SAM-R/1/Ta (SAM-R/1, senescence-resistant substrain) in a novel environment when the activity was measured in the light period, although there was no significant difference in the dark period. In observations of the circadian rhythm of SMA, SAM-P/8 showed a significant increase in diurnal SMA. In SAM-P/8 mice, the acquisition of passive avoidance response was slightly but significantly impaired even at 2 months of age, compared with SAM-R/1 control; the impairment became obvious with aging. In a one-way active avoidance task, SAM-P/8 did not show any impairment in the acquisition of avoidance response at 2 and 4 months of age. However, significant impairment was observed in SAM-P/8 at 12 months of age. The impairments of avoidance tasks were not due to a decrease in shock sensitivity, as indicated by no significant change in the flinch-jump threshold. In a water-filled multiple T-maze task, there was no difference in the number of errors between the two groups. With regard to the performance time to reach the goal, however, SAM-P/8 showed a mild prolongation at 2 months of age, and the prolongation became marked with advancing age.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebral embolization impairs memory function and reduces cholinergic marker enzyme activities in various brain regions in rats.

Cerebral embolization was produced by injecting microspheres into the left internal carotid artery in rats. In these embolized rats, passive avoidance response was impaired at early stages after the embolization (3 days, 1 and 2 weeks), but 4 to 8 weeks later, recovery was achieved. A reduction in the activities of choline acetyltransferase (CAT) in the left side of the occipital cortex and hippocampus was observed in parallel with the impairment of learning behavior. These results suggest that impairments in the septo-hippocampal cholinergic pathways are likely to be closely related with the behavioral impairment in these rats.

Characteristics of memory impairment in cerebral embolized rats at the chronic stage.

The effect of cerebral embolization on learning and memory in rats was studied at the chronic stage (8 weeks or more after embolization). At the chronic stage, embolized rats showed no significant change in emotional behavior, but exhibited an increase in ambulation in the open-field test. Rats with cerebral embolization exhibited marked impairment of the response was observed at the chronic stage. In a two-way active avoidance task, embolized rats showed accelerated acquisition of the avoidance response in comparison with a sham-operated control group. However, at the chronic stage, embolized rats exhibited marked impairment of light-dark discrimination learning. Spatial memory impairment was also observed in embolized rats, as demonstrated by a significant decrease in initial correct responses and an increase in total errors in the radial maze task. Upon microscopic examination, multi-focal necroses were detected in several brain regions, being particularly obvious in the hippocampus and internal capsule of the embolized hemisphere. These results demonstrate that embolized rats show definite impairment of memory and learning at the chronic stage, and suggest that the impairment may be qualitatively different from that observed at the early stage.

Cerebral embolization leads to memory impairment of several learning tasks in rats.

The effects of cerebral embolization, produced by injecting microspheres into the left internal carotid artery, on passive and active avoidance tasks and water filled multiple T-maze task, were studied in male Wistar rats. The rats with cerebral embolization were markedly impaired acquisition and retention of the one-trial passive avoidance response. The impairment depended on the number of microspheres injected and continued for 2 weeks. The cerebral embolized rats were also impaired acquisition of two-way active avoidance response in a shuttle box. These impairments are not due to decrease in shock sensitivity, because there was no significant change in the flinch-jump threshold. The embolized rats also exhibited a significant disturbance in performance of water filled multiple T-maze learning. These results suggest that rats with cerebral embolization are impaired in three different types of learning tasks, and may be useful as an animal model for the vascular type of dementia.

Protective effect of idebenone against hypoxia in mice.

The effects of idebenone on survival time of mice subjected to hypoxia induced by N2 and CO2 inhalation and KCN injection were studied. Idebenone (10, 20, 50 and 100 mg/kg, i.p.) prolonged the survival time of mice exposed to a hypoxic condition (98% N2, 2% O2) in a dose-dependent manner: significant prolongations were observed at doses higher than 20 mg/kg. The drug also exerted a similar elongation effect at the same doses under conditions of 100% CO2 gas inhalation and KCN injection (3 mg/kg, i.v.). The results suggest that idebenone protects against hypoxia by improving cerebral energy metabolism.

Effects of idebenone on memory impairment induced in ischemic and embolization models of cerebrovascular disturbance in rats.

Two rat models of memory impairment in passive avoidance learning induced by cerebrovascular disturbance, were established to estimate the effects of a cerebral metabolic enhancer, idebenone. Transient and global cerebral ischemia in rats, produced by 4-vessel occlusion for 200 s immediately after the acquisition trial of passive avoidance learning, shortened the latencies in the retention test trial performed 24 h later. This retrograde amnesia was reversed significantly by idebenone administered orally or intraperitoneally at the doses of 10 and 30 mg/kg before the retention test trial. Idebenone at a dose of 10 mg/kg, given intraperitoneally before or immediately after the ischemia, also markedly inhibited the appearance of amnesia. In the second model, permanent and cerebral hemisphere embolization produced by injecting 2,000 microspheres into the internal carotid artery, significantly impaired passive avoidance learning performed 7 days later. The repeated administration of idebenone (30 mg/kg, i.p.). once a day after the embolization, significantly improved the impairment of passive avoidance learning in the embolized rats. Furthermore, physostigmine and arginine-vasopressin as reference compounds improved the impairment of passive avoidance learning in these models. These findings suggest that idebenone ameliorates memory impairment induced by cerebral vascular disturbance in rats.

[A case of familial juvenile Alzheimer's disease with apallic state at the relatively early stage and various neurological features--a clinicopathological study].

A case of familial juvenile Alzheimer's disease with apallic state at the relatively early stage and various neurological features was reported. A 33-year-old woman showed a progressive dementia followed by apallic state at the relatively early stage, and died of cardiac failure at the age of 45. Neurological examination disclosed chorea, myoclonus, rigidity, pyramidal sign, and generalized convulsion. Neuropathologically, extensive senile changes such as senile plaques, neurofibrillary tangles, and granurovascular degenerations were observed in the brain, chiefly in the cerebral cortex and limbic system. The present case was characterized by a severe neuronal loss in the subcortical gray matter such as the caudate nucleus, dentate nucleus, substantia nigra, and thalamus as well as a marked myelin loss and axonal damages in the cerebral white matter. This case suggested a combination of multisystemic degeneration and a primary degeneration of the cerebral white matter. The additional peculiar aspects in this case were the senile plaques and amyloid angiopathy in the cerebellar cortex, and the senile plaques and grumose degeneration in the cerebellar dentate nucleus. In the clinicopathological standpoint, the apallic state in this case could be attributed to a severe degeneration of the cerebral white matter in addition to the cerebral cortical deterioration. Furthermore, the occurrence of chorea and myclonus might be contributed to the severe degeneration of the caudate nucleus and to the degeneration of the dentate nucleus, particularly to the grumose degeneration, respectively.

[Surgical treatment of aortic arch aneurysm associated with the aberrant right subclavian artery].

A 64-year-old man, who had an aneurysm of aortic arch associated with the aberrant right subclavian artery, was treated successfully. He was pointed out to have an aneurysm of aortic arch three years ago. Three years later angiograms and computed tomography revealed that it became larger compared with the initial finding. He underwent a replacement of the aortic arch using a woven Dacron graft under open distal method. Aberrant subclavian artery was not involved in the aneurysm. But because the left subclavian artery was involved in it, a woven Dacron graft was interposed between the ascending aorta and left subclavian artery. Postoperative course was uneventful and there were no complications.

[Size and configuration of the functional aortic root after the arterial switch operation for complete transposition of the great arteries].

Twelve patients with complete transposition of the great arteries who had arterial switch operation were investigated by postoperative cineangiogram to assess the size and configuration of the functional aortic root. Three patients underwent Damus-Kaye-Stansel operation and the remaining nine received Lecompte modification of Jatene operation. Aortogram showed trivial or mild aortic regurgitation in six patients who underwent Jatene operation but no regurgitation was detected in patients after Damus-Kaye-Stansel operation, arterial switch operation without coronary relocation. The patients were divided into two groups according to the aortographic findings: AR(-); patients with competent aortic valve, AR(+); patients with incompetent aortic valve. Comparison was made between these two groups, measuring new aortic root diameter at three levels. The systolic diameter of distal aortic root was significantly enlarged in AR(+) group as compared to AR(-) group. These results suggest that the relocation of the coronary arteries and the dilatation of aortic root may contribute to aortic regurgitation after Jatene operation.