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Biomedical subjects

H Ashida

Publications and source records attributed to H Ashida.

At least 127 records · Page 7Linked to original sources
PubMed1989

Effects of LTP-inducing tetanic stimulations of the perforant path on the commissural inhibition and facilitation of dentate granule cell discharge.

Effects of diazepam (1 mg/kg, i.p.) on the commissural influences on granule cells were first examined to further assess its GABAergic inhibitory mechanism. Whereas the commissural inhibition at an interval of 5-8 ms of the contralateral dentate-perforant path (CP) combined stimulus was not enhanced by diazepam, the commissural facilitation at a CP interval of 11-20 ms was reduced, suggesting that the GABAergic inhibition is involved in rather a part of the commissural facilitation at a CP interval of 11-20 msec than a part of the 'commissural' inhibition at a shorter CP interval. Based on the results of diazepam, effects of high-frequency stimulations of the perforant path on the commissural inhibition of dentate granule cells were then examined, in relation to their effects on the dentate paired-pulse depression. These stimulations produced the long-term potentiation of the perforant path-dentate excitatory synapse and significant reduction of the paired-pulse depression. The commissural inhibition at a CP interval of 5-8 ms remained unchanged following tetanization. The commissural facilitation at a CP interval of 11-20 ms was, however, slightly enhanced by tetanic stimulations and a statistical significance was obtained at a CP interval of 19 ms. These results imply that tetanic stimulations of the perforant path selectively reduce the GABAergic component of the commissural inhibition, as well as that of the paired-pulse depression.

Action Potentials↗
PubMed1989

Long-lasting reduction of dentate paired-pulse depression following LTP-inducing tetanic stimulations of perforant path.

Effects of high-frequency stimulations of the perforant path on the dentate paired-pulse depression were examined in urethane-anesthetized rats. The tetanic stimulations produced a long-term potentiation (LTP) of the excitatory synaptic transmission at the perforant path-dentate granule cell synapses in almost all animals examined. The strength of the early paired-pulse depression at an inter-pulse interval (IPI) of 20 ms decreased significantly for at least 60 min after the tetanic stimulations, whereas the late paired-pulse depression at an IPI of 2 s remained almost unchanged. The reduction of the early paired-pulse depression was stepwise augmented by each of successive tetanic stimulations given at an interval of 10 min. A preceding antidromic stimulation of the mossy fibers depressed the population spike amplitude of perforant path response at an interval of 5-9 ms. The strength of the antidromic depression of population spike also decreased following the perforant path tetanic stimulations. These results suggest that tetanic stimulations of the perforant path produce a long-lasting reduction of the GABAergic recurrent inhibition in the dentate area associated with LTP. The possible mechanisms of the decrease in GABAergic inhibition produced by tetanic stimulations and its possible effects on the development of LTP with succeeding tetanic stimulations were discussed.

Action Potentials↗
PubMed1989

Microcomputer-controlled laboratory system for field potential experiments.

A microcomputer-controlled laboratory system for hippocampal field potential experiments was constituted. This system realized the quasi-simultaneous processing of execution of stimulation, data acquisition, data display and data analysis by means of a microcomputer for the first time. To attain this quasi-simultaneous processing, a new algorithm for drawing a tangent on the wave-form of the potential was contrived, which enabled rapid analysis of an arbitrary population spike even in the case of generation of double spikes. The system has the following functions: (1) execution of the programmed stimulation paradigm, (2) analog/digital (A/D) conversion of the evoked field potential with a sampling interval of more than 50 microseconds per channel, (3) display of the A/D converted wave-form data on a CRT and storage of the data on a floppy disk, (4) on-line analysis of the population excitatory postsynaptic potential (EPSP) and population spike, (5) more detailed off-line analysis of the field potentials, and (6) output of the wave-form data and measured values through a printer and an X-Y plotter.

Action Potentials↗
PubMed1989

Results of distal splenorenal shunt with versus without splenopancreatic disconnection.

From December 1973 to December 1987, we performed a distal splenorenal shunt (DSRS) in 112 cases of portal hypertension, including 107 with postnecrotic liver cirrhosis and 5 with idiopathic portal hypertension (IPH). They comprised about 50% of our surgical cases with esophageal varices. In 1981, we modified our operative procedure towards a more extended splenopancreatic disconnection (SPD) in order to prevent the "stealing" of the shunt through the pancreatic vein. In one group of 69 patients who underwent DSRS alone, the operative mortality was 2.9%; postoperative encephalopathy was seen in 17.4%, late hepatic failure in 40.6%, and recurrence of varices in 4.3%. In the other group, 43 patients who underwent DSRS with SPD, there were no operative deaths, no encephalopathy (better than DSRS alone at p less than 0.05), and late hepatic failure was seen in only 9.3% (better than DSRS alone at p less than 0.025), while the recurrence rate of 7% was the only statistical increase. These data show that DSRS + SPD can improve chances of survival.

Collateral Circulation↗
PubMed1989

Depletion of hepatic coenzyme A derivatives is one of the markers of the toxicity of orally administered secondary autoxidation products of linoleic acid in rat.

When 400 mg/rat/day of secondary autoxidation products of linoleic acid was orally administered 3 times to rats, they died at 30-40 h after the third dose. To search the markers of the toxicity of secondary products in vivo, the rats were killed at 24h after the third dose, and conditions of their digestive tracts and liver were analyzed. In the stomach, macroscopically, inflation, retention of undigested food, and edema were seen. Slight congestions were detected in the small intestines. It was considered that these injuries led to reduction in food consumption and then depression of the growth, but did not lead to the death of the animals. The lipid peroxide levels in the liver and the activities of its detoxifying enzymes were increased as compared to those in the control groups. The hepatic lipid contents and unsaturated fatty acid compositions were also not changed. The endogenous lipid peroxidation, therefore, did not give the rats a severe stress. The activities of hepatic acetyl-CoA carboxylase and carnitine palmitoyltransferase were 20 and 35% lower than those of control, respectively. The levels of CoASH, acetyl-CoA, and long-chain acyl-CoA were 1/9, 1/2, and 1/4 of those in control, respectively. Thus, one of the markers of the toxicity of secondary products was the depletion of hepatic CoA derivatives. In rat, bio-energy was reduced by the decrease in the intestinal absorption of nutrients, and the depletion of hepatic CoA derivatives also failed to supply energy with beta-oxidation.

Animals↗
PubMed1989

Succinate dehydrogenase and synthetic pathways of glucose 6-phosphate are also the markers of the toxicity of orally administered secondary autoxidation products of linoleic acid in rat liver.

In order to find the markers of the toxicity of the autoxidized lipids in the liver, rats were given a lethal amount of secondary autoxidation products of linoleic acid (400 mg/rat/day for 3 days) and then changes in the hepatic metabolic functions were analyzed. A decrease in acetyl-CoA level to half caused by the depletion of CoASH was reported in an associated paper (J. Nutr. Sci. Vitaminol., 35, 11-23, 1989). Citrate, isocitrate, and 2-oxoglutarate also decreased to half the level of those of the control group. Reduction in isocitrate dehydrogenase activity was only 25%, while NADH2 and ATP levels remained unchanged. Thus, the reduction in the citrate cycle activity was due to the decrease in acetyl-CoA. The activity of mitochondrial succinate dehydrogenase was decreased to 1/5. Other appreciable changes were depletion of glucose 6-phosphate and fructose 6-phosphate, accumulation of glucose 1-phosphate, reductions in hexokinase, phosphofructokinase, glucose-6-phosphatase, phosphoglucomutase, and phosphogluconate dehydrogenase activities, and decrease in the NADPH2 level. It was considered that these changes were caused by the depletion of glucose 6-phosphate whose synthetic pathways were abnormal. Therefore, the markers of the hepatotoxicity of secondary products were the changes in the CoASH level and the activities of succinate dehydrogenase and synthetic pathways for glucose 6-phosphate.

Animals↗
PubMed1989

[Interventional radiology of benign bile duct diseases].

The authors describe percutaneous interventional procedure for bile duct benign disease from our own experiences and review of the literatures. Percutaneous dilatation of bile duct stricture is widely employed but is associated with 20-30% recurrence rate. It may be the limitation of present procedure and controversy still exists about long-term post dilatation stent. Self-expandable stainless steel stent have potential advantage and it's future development is expected. Percutaneous removal of common bile duct from percutaneously placed biliary drainage is not routine procedure. Endoscopic sphincterectomy is preferred as initial non-surgical treatment. But recent technological improvement makes this technique safe and simple. Balloon dilatation of Ampullar of Fater and extraction of stone into the duodenum is a effective alternative to endoscopic sphincterectomy. Percutaneous removal of multiple intrahepatic stones with choledochoscopic guidance is well accepted method. Adequate selection of access route and balloon dilatation of multiple stenosis are essential for a success. Extra-corporal shock wave lithotripsy is one adjunct in difficult cases.

Adult↗
PubMed1989

Portal and mesenteric venous thrombosis as a complication of endoscopic sclerotherapy.

We report on the occurrence of portal and mesenteric venous thrombosis in two patients who underwent endoscopic injection sclerotherapy (EIS) for bleeding esophageal varices. One patient was diagnosed at autopsy, and portal and mesenteric venous thrombosis was not suspected during life. The second patient was suspected on ultrasound examination and was diagnosed by angiography. In the second case, therapy was effective and symptoms disappeared. He was treated by a distal splenorenal shunt after he had stabilized for 1 month. During the operation, no evidence of mesenteric infarction was found. The venous phase of the superior mesenteric arteriogram 1 month after surgery revealed an organized thrombosis in the right intrahepatic portal branches. No other thrombi were seen. This patient is the first reported who has survived portal and mesenteric venous thrombosis after sclerotherapy.

Aged↗
PubMed1989

Severe hemolysis after distal splenorenal shunt.

We report a case of severe hemolysis after distal splenorenal shunt. Hemolysis was suddenly recognized at the time splenorenal venous anastomosis was completed, and it continued on the operative day and the first postoperative day. After the shunt, the intraoperative splenic venous blood flow was approximately double its previous level, as measured by electromagnetic flowmeter. Angiographic partial splenic embolization was performed on the second postoperative day, and then hemolysis stopped suddenly. This suggested that hemolysis after distal splenorenal shunt was related to increased splenic blood flow and acceleration of erythrocyte destruction.

Hemoglobinuria↗
PubMed1988

Effect of orally administered 9-oxononanoic acid on lipogenesis in rat liver.

9-Oxononanoic acid, which is one of the major products of the autoxidation of linoleic acid, was administered orally to rats and its effect on hepatic lipid metabolism was investigated. The de novo synthesis of fatty acids was strongly reduced 30 h after the administration of 100 mg of 9-oxononanoic acid as compared to that in the saline-administered group. Activity of acetyl-CoA carboxylase decreased by 60% and the activity of carnitine palmitoyltransferase increased by 35% in the test group. The level of triacylglycerols in serum was low and the level of free fatty acids remained unchanged. Thus, the administration of 9-oxononanoic acid decreased hepatic lipogenesis. It is generally believed that the reduction in lipogenesis is facilitated by a decrease in the NADPH level. The ratio of NADPH/NADP in the test group, however, became high as compared to that in the control group, and the activities of glucose 6-phosphate and isocitrate dehydrogenases increased. On the other hand, the levels of CoA derivatives, especially long-chain acyl-CoA, were higher in the test group than in the control. Therefore, the reduction of hepatic lipogenesis in the 9-oxononanoic acid group could be attributed to the inhibition of acetyl-CoA carboxylase by the accumulated long-chain acyl-CoA.

Acetyl-CoA Carboxylase↗
PubMed1988

Objective evaluation of differences in patterns of EEG topographical maps by Mahalanobis distance.

The purpose of this work was to develop a method to objectively evaluate differences in topographical patterns between 2 groups of isopotential maps. Previous evaluations by other investigators had been based on subjective judgment which created problems in describing differences in patterns, particularly when the differences were subtle. In the method presented in this report, the differences are evaluated by the Mahalanobis distance calculated from polynomial coefficient vectors obtained from unbiased polynomial interpolation in order to calculate values of picture elements in the 2-dimensional maps. One polynomial coefficient vector corresponds to one pattern of the map, containing both EEG and locational information. Examples of the evaluation are shown in the maps of fast activities induced by the injection of thiopental, diazepam or both drugs to an adult volunteer. In 5 experimental situations (A, control; B, thiopental; C, thiopental and diazepam; D, diazepam; and E, diazepam and thiopental administration), the polynomial coefficient vectors were obtained. When Mahalanobis distances (Q value) between the 2 maps for the 5 situations, arranged in 8 different combinations, were calculated, the values corresponded significantly to the pattern differences found between the maps. The greater the Q value, the more dominant the pattern difference. The objective evaluation method presented in this report has significant advantages over the subjective method previously reported and should be of interest to investigators attempting to quantify topographical pattern differences.

Adult↗
PubMed1988

An electromyography in spastic diplegia.

To evaluate the pathologic state accurately and objectively, fifteen patients with spastic diplegia were examined with surface electromyography (EMG) of the rectus femoris, medial hamstring, anterior tibial and gastrocnemius muscles. Seven showed disturbed reciprocal innervation (disturbed group) and 8 showed reciprocal innervation (non disturbed group). The disturbance of reciprocal innervation on EMG showed a positive correlation with delay in onset of crawling by 10 months (p less than 0.05), a low level of motor development (p less than 0.005) and more abnormal CT findings. Four patients in the disturbed group showed various abnormalities in X-rays of the hips. Surface EMG findings of crawling muscle may be useful for understanding the pathologic state of crawling in spastic diplegia.

Cerebral Palsy↗
PubMed1988

The effects of orally administered linoleic acid and its autoxidation products on intestinal mucosa in rat.

Linoleic acid and its autoxidation products, hydroperoxides and their secondary products, were orally administered to rats (350 mg each/rat). Hemorrhage was seen in the alimentary canal at 6 h after the dose of hydroperoxides. To examine their toxicities on intestinal mucosa, the activities of mucous enzymes (sucrase, maltase, and alkaline phosphatase) were measured. Hydroperoxides and their secondary products decreased the enzyme activities in jejunum at 6 h after the doses and increased them in both jejunum and ileum at 15 h, as compared to linoleic acid or saline solution. The decrease of enzyme activity was marked in the hydroperoxide group and the increase was marked in the secondary product group. Then, in in vitro experiments, the effects of autoxidation products on these enzymes were determined. Autoxidation products inactivated only alkaline phosphatase. Thus, the results in vivo disagreed with those in vitro. It was assumed that autoxidation products orally administered attacked a membrane of intestinal microvilli whereas in vitro they directly affected the enzymes.

Administration, Oral↗
PubMed1988

[Improvement of selectivity of distal splenorenal shunt and its clinical analysis].

Follow up studies of 96 patients who underwent distal splenorenal shunt (DSRS) were performed and the loss of selectivity of DSRS was evaluated. We have established the indications for DSRS since 1980 and modified the procedures for DSRS--complete or incomplete splenopancreatic disconnection of the splenic vein (SPD)--since 1981. Twenty two of 47 patients operated before 1980 and 9 of 49 patients operated after 1980 were died of liver failure, being statistically significant (p less than 0.05). There were no significant differences in the incidence of development of encephalopathy before and after 1980 (7 patients before 1980 and 6 patients after 1980). Twenty eight of 69 patients without SPD and one of 16 patients with incomplete SPD were died of liver failure, being statistically significant (p less than 0.025). Twelve of 69 patients without SPD developed encephalopathy, while none of 27 patients with complete or incomplete SPD developed encephalopathy (p less than 0.05). It was suggested, therefore, that our established indications and DSRS with complete or incomplete SPD might be suitable for the selective shunt operation for esophageal varices.

Esophageal and Gastric Varices↗
PubMed1987

Effect of orally administered secondary autoxidation products of linoleic acid on carbohydrate metabolism in rat liver.

The effects of orally administered secondary autoxidation products of linoleic acid in rat liver were investigated. Their administration led to two toxic effects on hepatic carbohydrate metabolism, as compared to the administration of saline or linoleic acid used as controls. One effect was depletion of glucose 6-phosphate and fructose 6-phosphate caused by the reduction of glycolysis and glycogenolysis, accompanied by decreases in glycogen synthesis and pentose phosphate cyclic activity. The reduction in these metabolic systems seems unlikely to occur because phosphofructokinase was regulated by ATP or citrate enzymatically, because their accumulation in the liver was not detected in the secondary products. Another toxic effect was the depletion of oxaloacetate and isocitrate caused by the reduction in enzyme activity of the mitochondrial citrate cycle. On the basis of these results, the hepatotoxic effects of secondary products are discussed as follows: the incorporated secondary products impaired the activities of hexokinase and phosphoglucomutase in the liver. The reduction in these enzyme activities resulted in the depletion of glucose 6-phosphate and fructose 6-phosphate, which led ultimately to decreases in the activities of phosphofructokinase, the pentose phosphate cycle, and glycogen synthesis. Moreover, the secondary products disturbed the mitochondrial membrane, resulting in a decrease in the activity of the citrate cycle, which was accompanied by depletion of its metabolites.

Adenine Nucleotides↗