Search PubMed⌕ Search

Biomedical subjects

H Yokoi

Publications and source records attributed to H Yokoi.

At least 55 records · Page 3Linked to original sources
PubMed1999

Identification of prostaglandin F-producing cells in the liver.

Prostaglandin (PG) F synthase forms PGF(2alpha) and 9alpha, 11beta-PGF2 from PGH2 and PGD2, respectively. PGH2 is synthesized from arachidonic acid by cyclooxygenase (COX) and then metabolized to various PGs and thromboxane by specific enzymes. PGD2 is synthesized from PGH2 by PGD synthase. To identify PGF2-producing cells in the rat liver, the occurrence and localization of PGF synthase and COX were studied with immunochemical and immunohistochemical techniques using anti-liver-type PGF synthase and anti-COX antibodies. In Western blot analyses, positive bands of liver-type PGF synthase and constitutive COX-1 were observed at positions approximately 37 kDa and 70-72 kDa, respectively. However, inducible COX-2 was not detected. In the immunohistochemical study, PGF synthase was present in the cytoplasm of the sinusoidal endothelial cells. COX-1 was present on the membranes of the nucleus and endoplasmic reticulum of the endothelial cells and Kupffer cells. Double immunostaining for PGF synthase and COX-1 showed that both enzymes were present in the same endothelial cells. These results suggest that the main site of PGF2 synthesis in the liver is the sinusoidal endothelial cell.

Animals↗
PubMed1999

Clinicopathological features and outcome of hepatic resection for intrahepatic cholangiocarcinoma in Japan.

As a result of an increasing number of studies on the surgical treatment of intrahepatic cholangiocarcinoma (ICC), knowledge of its biological characteristics has been accumulating. We analyzed the clinicopathological features and outcome of 36 of 48 surgical patients with histologically proven ICC (75.0%) who underwent hepatic resection between March 1979 and July 1998. According to tumor location, 12 patients had the central type and 24, the peripheral type. The incidence of portal vein tumor thrombus and lymph node metastasis was higher in the central type than in the peripheral type. All 12 patients with the central type had stage IV disease, and none of them underwent complete resection, whereas 12 of the 24 patients with peripheral type tumors had stage IV disease; complete resection was achieved in 12 of the 24 patients with peripheral type tumors (50%). Outcome after resection was significantly poorer in the patients with the central type. The macroscopic type of lesion in the resected specimens was the mass-forming type in 15 patients (41.7%), the mass-forming + periductal-infiltrating type in 15 patients (41.7%), the periductal-infiltrating type in 3 patients (8.3%) and the intraductal growth type in 3 patients (8.3%). The macroscopic tumor type was associated with mode of tumor spread and outcome. All 3 patients with the intraductal growth type are alive without tumor recurrence 26-138 months after surgery. The survival rate was much higher in the patients with the mass-forming type than in those with the mass-forming + periductal-infiltrating type. Importantly, the outcome in the 17 patients who underwent resection for stage IV-B disease and who accounted for 47.2% of patients with resection in the present series was very poor, almost the same as that in the 12 patients who did not undergo resection. By selecting patients based on the biological characteristics of the tumor and taking into account patients' quality of life, complete surgical resection can be performed safely and is associated with long-term survival.

Aged↗
PubMed1999

Rapid and sensitive vasopressin heteronuclear RNA responses to changes in plasma osmolality.

The plasma concentration of arginine vasopressin (AVP) is closely regulated by plasma osmolality. In this study, we used intronic in-situ hybridization to investigate the transcriptional activity of the AVP gene in the supraoptic nucleus (SON) and paraventricular nucleus (PVN) after intraperitoneal (i.p.) injection of hypertonic saline inducing small changes in plasma osmolality in rats. After ip injection of 900 mOsm/kg saline (2% BW), plasma [Na] reached the highest level at 10 min (900 mOsm/kg, 146+/-1 mEq/l; 290 mOsm/kg, 139+/-1 mEq/l, P<0.01) and maintained that level until 30 min. The expression of AVP heteronuclear (hn) RNA in the SON and PVN increased significantly as early as 10 min and peaked 30 min after ip injection of the hypertonic saline. AVP hnRNA expression showed a significant increase even after a 2 mEq/L elevation in plasma [Na] concentration, and increased dose-dependently in response to the concentration of saline injection (290-900 mOsm/kg). These results demonstrate that, similar to AVP secretion, AVP gene transcriptional activity in the SON and PVN is closely regulated by plasma osmolality.

Animals↗
PubMed1999

Prospective study of a protocol for selection of treatment of acute pancreatitis based on scoring of severity.

BACKGROUND/AIM: Since July 1994, we have been conducting a prospective study of a protocol for selection of treatment of acute pancreatitis based on scoring of severity. METHODS: From July 1994 to June 1998, 56 patients with acute pancreatitis were enrolled in this study. The protocol employed was based on the results of our retrospective study. On admission, the prognosis score (scoring of severity of acute pancreatitis based on the criteria of the Ministry of Health and Welfare of Japan) and APACHE II score were calculated, and early treatment was selected according to the protocol. RESULTS: All of the 26 patients with gallstone pancreatitis and 28 of 30 patients with non-gallstone pancreatitis were successfully treated and had good outcome. There were 2 deaths in non-gallstone pancreatitis. In selection of early treatment according to the scoring of severity, we suggested that when the prognosis score is 2 or more and the APACHE II score of 8 or more, gallstone pancreatitis should be treated by biliary drainage, and non-gallstone pancreatitis by peritoneal lavage. When infected pancreatic necrosis is exhibited, surgery is indicated. CONCLUSION: Our new management protocol for acute pancreatitis based on the prognosis score and APACHE II score appear to be useful for accurately scoring severity and selecting the treatment methods.

Acute Disease↗
PubMed1999

Effect of IS-741 (a new synthetic antiinflammatory agent) on acute necrotizing pancreatitis in dogs. Significance of its inhibitory effect on cytosolic phospholipase A2.

IS-741, a new synthetic anti-inflammatory agent, is known to have some inhibitory effect on cytosolic phospholipase A2 (cPLA2), an enzyme which hydrolyzes cellular phospholipids, liberating fatty acids and lysophospholipids and providing the precursor substrates for the biosynthesis of eicosanoids and platelet-activating factor. cPLA2 is therefore an attractive target for the development of novel therapies. During infusion of lactated Ringer's solution at a rate of 10 ml/kg/h, acute pancreatitis was induced in dogs by injecting autologous gallbladder bile into the main pancreatic duct. The dogs were then divided into two groups: group A (nontreatment), no treatment during the experiment, and group B (IS-741), intravenously injected with IS-741 at 6 and 30 h after induction of acute pancreatitis. As a result, the survival rate was significantly higher in group B than in group A. Mean arterial pressure and PaO2 were well maintained in group B as compared with group A. The NAG index, which is known to be markedly increased in renal tubular damage, was significantly lower in group B than in group A. Histological examination of the pancreas, lung, and kidney in group B showed milder changes than in group A. cPLA2 activity in the pancreas, lung and renal cortex was much lower in group B than in group A, but sPLA2 activity in these tissues did not differ significantly between the two groups. In conclusion, IS-741 exerts a potentially therapeutic effect on experimental acute pancreatitis by mitigating the degree of damage in the pancreas, lung, and kidney. The inhibitory effect of IS-741 on cPLA2 may contribute to one of the antiinflammatory mechanisms of actions of this agent.

Animals↗
PubMed1999

Modified standard pancreaticoduodenectomy for the treatment of pancreatic head cancer.

Since 1980 extended surgery has been used to treat pancreatic cancer in many institutions in Japan in the hope of achieving curative resection and a good outcome. The resection rate increased, but the final outcome was unsatisfactory, and the question of postoperative quality of life (QOL) following extended surgery has instead become the central issue. During the past 22 years (October 1976 to June 1998) 169 of the 188 patients with invasive pancreatic ductal carcinoma at Mie University Hospital were treated surgically. A standard operation was performed in the early period (October 1976 to April 1981, n = 34), an extended operation was performed in the middle period (May 1981 to March 1993, n = 100), and a modified standard operation was performed in the late period (April 1993 to June 1998, n = 35). 'Standard operation' means pancreaticoduodenectomy (PD) with D1 lymph node dissection (regional), and 'extended operation' means PD with D2-D3 lymph node dissection. Our 'modified standard operation' consists of PD with lymph node dissection limited to the anterior pancreaticoduodenal (APD), posterior pancreaticoduodenal (PPD), pyloric (PY), hepatoduodenal ligament (HDL), common hepatic artery (CH) and right half of the superior mesenteric (SM) nodes. Thus, the extent of lymph node dissection in the modified standard procedure lies between the level in the standard and extended procedure, but the PD is the same, with only slight modification in the reconstruction procedure. We consider the standard operation to be a less curative procedure and the extended operation to be a very stressful procedure and accordingly we have modified it (modified standard operation) in our recent cases out of consideration for patients' QOL. We found that postoperative QOL and survival were much better in the late period than in the early and middle periods.

Humans↗
PubMed1999

[Correlation of risk area and reverse redistribution of 99mTc-sestamibi SPECT in acute myocardial infarction following direct PTCA].

Redistribution of 99mTc-sestamibi is negligible in usual circumstances, but recent reports demonstrated reverse redistribution is detectable in acute myocardial patients. Correlation of risk area, observed in 99mTc-sestamibi "freezed" SPECT image at onset, and delayed images at 5-25 days after onset (post-PTCA image) is evaluated in 19 acute myocardial infarction patients treated with direct PTCA. Reverse redistribution was observed in 85% of reperfused area. Linear relationship of % uptake in each SPECT segment between onset and post-PTCA images (taken at 0.5, 4, and 6 hours after injection) is evaluated and the relationship improves over time course. The correlation coefficient between onset and 6 hours-delayed image is 0.88, and the visual concordance shows 77% of score matching. Delayed 99mTc-sestamibi SPECT image on reperfused AMI seems to represent risk area with some underestimation. It may be useful to estimate both risk and salvaged areas on early and delayed SPECT with a single 99mTc-sestamibi injection.

Adult↗
PubMed1999

[Efficacy of hemostatic puncture closing device for hemostasis and early ambulation after coronary angiography and angioplasty: results of a multicenter trial].

To assess the efficacy and safety of a hemostatic puncture closing device for reducing patient immobilization after cardiac catheterization from a percutaneous femoral artery approach, we conducted a prospective, randomized trial at 4 participating centers. A total of 240 patients (183 men, 57 women, mean age 61 +/- 10 yr; 157 patients underwent diagnostic angiography, 83 patients underwent coronary angioplasty) were randomized to either the device group (n = 120) or the manual compression group (n = 120). There were no statistical differences in age, gender, weight or sheath size between the 2 groups. A 7, 8F sheath was used in 53 patients of the device group and in 43 patients of the manual compression group. One hundred and two patients (85%) in the device group and 96 patients (80%) in the manual compression group received heparin. Protamine was used in one patient of the device group and 23 patients of the manual compression group. Activated clotting time just prior to sheath removal was 206 +/- 64 sec in the device group and 170 +/- 47 sec in the manual compression group (p < 0.01). Successful placement of the device was achieved in 118 of 120 patients (98%). Time to hemostasis was significantly shorter in the device group (0.8 +/- 3.2 vs 12.2 +/- 5.3 min, p < 0.01). Time to ambulation could be reduced in the device group (5.3 +/- 3.7 vs 10.9 +/- 5.1 hr, p < 0.01). The following complication rates occurred in the device group as compared with the manual compression group: hematoma, 16% vs 10%; bleeding, 8% vs 3%; pseudoaneurysm, 0% vs 1%, respectively. None of these differences was statistically significant. These results indicate that early ambulation using a hemostatic puncture closing device is feasible without significantly increasing the risk of peripheral vascular complications.

Adult↗
PubMed1999

Human antibody isotype responses to Schistosoma japonicum egg antigen.

Schistosoma japonicum-infected subjects from Hubei province of China were investigated to determine the class and subclass of the antibody response to soluble egg antigen (SEA), using an enzyme-linked immunosorbent assay. The subjects were 50 acute and 55 chronic cases. In acute cases, the mean OD values for IgA, IgE and IgG3 were very high, while the positive ratios of IgA and IgE were only 78% and 74%, respectively. The positive ratios of IgG, IgM, IgG1, IgG3 and IgG4 were all above 90%. In chronic cases, the mean OD values for IgG, IgG3 and IgG4 were very high, and the positivity rates of IgG, IgG1, IgG3 and IgG4 were all above 90%. Comparing the two study groups, the mean OD values of IgM, IgA, IgE were higher in acute cases than those of chronic cases (p < 0.0001), while the mean OD values of IgG, IgG4 were higher in chronic cases than in acute cases (p < 0.05). The mean OD values of IgG3 in both groups were high and those of IgG2 in both groups were low.

Acute Disease↗
PubMed1998

Correlation analysis between fatty acid compositions of zooplankter individuals, fed on different phytoplankton species by means of pyrolysis-gas chromatography combined with on-line methylation.

Pyrolysis-gas chromatography (Py-GC) combined with on-line methylation was applied to a correlation analysis between the distributions of fatty acid components in the lipids of zooplankter individuals and those of ingested algae using principal component analysis (PCA). Py-GC in the presence of organic alkali, tetramethylammonium hydroxide (TMAH), was used to estimate the apparent distributions of fatty acid components contained in a single individual zooplankter weighing several tens of micrograms and a small sample size of ingested algae samples in the order of 10 microg. The observed fatty acid compositions were used as a database for the PCA in order to discriminate the zooplankton and ingested algae samples. The result obtained indicated that the fatty acid compositions of zooplankton individuals used in this work were significantly reflected in those of their ingested food in spite of some contribution from isomerization and/or elongation of fatty acid components during digestion of the ingested algae phytoplankton in living zooplankters.

Animals↗
PubMed1998

Central administration of urocortin inhibits vasopressin release in conscious rats.

Urocortin (UCN) is a new mammalian member of the corticotropin releasing factor (CRF) family and supposed to be an endogenous ligand for type 2 CRF receptors. Previous studies have revealed that UCN mRNA exists in the supraoptic nucleus (SON), and that water deprivation increases UCN immunoreactivity in SON. In this study, we examined the effect of centrally-administered UCN on arginine vasopressin (AVP) release in conscious rats. Intracerebroventricular (i.c.v.) injection of UCN (5.0 microg/rat) significantly attenuated AVP release induced by hyperosmolality at 30 min after the injection. In contrast, CRF (5.0 microg/rat) injected i.c.v. had no significant effect on AVP release. These results suggest that central UCN play an inhibitory role in osmoregulation of AVP release.

Animals↗
PubMed1998

Stenting after thrombectomy with the AngioJet catheter for acute myocardial infarction.

The presence of massive intracoronary thrombi may contraindicate stenting. The AngioJet catheter rheolytic thrombectomy prepared the road for an easy and uneventful stenting in 2 patients with acute myocardial infarction (AMI) and thrombi. This combination provides a promising strategy for patients with AMI and angiographic evidence of massive thrombi.

Aged↗
PubMed1998

Initial and follow-up results of the ACS multi-link stent: a single center experience.

The Palmaz-Schatz (PS) stent has effectively reduced restenosis; however its rigidity makes it sometimes difficult or impossible to deliver. The initial and follow-up outcomes with the ACS Multi-Link stent (deployed from April to November 1995) were evaluated in 70 patients (79 lesions): unplanned in 34% (abrupt closure 1%; threatened closure 5%; suboptimal results 28%) and planned in 66%. Three to six month follow-up angiograms were analyzable in 67 lesions; 96% procedural (in nine lesions PS stenting had failed) and 95% clinical success were achieved. In-hospital mortality was 1.4%. Myocardial infarction occurred in 2.9%, and subacute stent thrombosis in 1.4%. Stenting improved immediately the minimal luminal diameter (from 0.97+/-0.41 mm to 2.72+/-0.31 mm), but at 6 months it had decreased to 1.89+/-0.44 mm. Angiographic restenosis (<50% diameter stenosis) occurred in 11, a rate of 16.4%; target lesion revascularization (TLR) was required in six (re-PTCA in five or bypass surgery in one; 6/67=8.7%). Actuarial 1-2 year survival rate was 91%, 80% surviving free from major complications or need for TLR. We conclude that the ACS Multi-Link stent can be implanted in lesions unsuited for the PS stent with a high success rate, and an anticipated restenosis rate perhaps comparable to with the PS stent.

Aged↗
PubMed1998

Steroid 5 alpha-reductase type 1 immunolocalized in the adrenal gland of normal, gonadectomized, and sex hormone-supplemented rats.

Steroid 5alpha-reductase in the rat adrenal gland is supposed to play a role in the catabolism of adrenal steroids. We showed immunohistochemically the cellular and subcellular localization of 5alpha-reductase in the rat adrenal gland, using a polyclonal antibody against 5alpha-reductase rat type 1. In the adrenal cortex, positive immunoreaction was found in the cells of the zonae fasciculata and reticularis but was absent in those of the zona glomerulosa. The positive staining was restricted to the cytoplasm but not to the nucleus, Golgi complexes or mitochondria. The staining intensity showed a marked change depending on the steroidal milieu. Gonadectomy for 6 weeks increased the immunoreaction, regardless of the sex. Testosterone replacement for the last 2 weeks considerably reduced the immunoreaction in 6-week-castrated males, and estradiol supplement for the last 2 weeks also resulted in the marked reduction of immunostaining in 6-week-gonadectomized females. In the adrenal medulla, the immunoreaction was localized in the supporting cells and the Schwann cells but not in the chromaffin cells. In these cells, the immunoreaction was not affected by steroidal treatments. These findings suggest that the expression of 5alpha-reductase in the rat adrenal cortex is regulated by sex hormones from the gonads, and the enzyme may participate in the conversion of adrenal steroids depending on the steroidal environment, although the functional significance of the enzyme in the adrenal medulla remains unclarified.

Adrenal Cortex↗
PubMed1998

Age-associated decrease in response of rat aquaporin-2 gene expression to dehydration.

It is well known that urine-concentrating ability decreases with aging and that this decreasing ability results from a reduced sensitivity of the renal collecting duct to arginine vasopressin (AVP). AVP regulates the water channel (aquaporin-2:AQP2) through V2 receptors and increases the water permeability of the collecting duct. To elucidate the mechanism of change with aging in urine-concentrating ability, we investigated the change of V2 receptor and AQP2 mRNA expression in young (8-week-old) and older (7-month-old) rats after dehydration for 2 days. After dehydration, plasma AVP levels in older rats were higher than young rats, and urinary osmolality in older rats was lower than young rats. By Northern blot analysis, there was no significant difference between young and older rats in both V2 receptor and AQP2 mRNA expression before dehydration. After dehydration, V2 receptor mRNA expression in young and older rats decreased in the same degree, suggesting the downregulation of V2 receptors may occur in the mRNA level. Northern blot analysis and in situ hybridization histochemistry showed that AQP2 mRNA expression increased and the increased expression in older rats was less than in young rats. The present study suggests the reduced response of AQP2 mRNA expression to dehydration, observed in 7-month-old rats, might be partially responsible for the decreasing urine-concentrating ability with aging.

Aging↗
PubMed1998

Antiserum against neuropeptide FF augments vasopressin release in conscious rats.

We previously reported that centrally administered neuropeptide FF (NPFF) inhibited arginine vasopressin (AVP) release. In this study, immunoneutralization of central NPFF was performed to evaluate the role of endogenous NPFF in the regulation of AVP release. Intracerebroventricular (ICV) injection of antiserum against NPFF (Anti-NPFF) significantly augmented the plasma AVP increase induced by hyperosmolality [intraperitoneal injection of hypertonic saline (600 mOsm/kg, 2% BW)] at 60 min after ICV injection compared with normal rabbit serum (NRS) (NRS: 4.20+/-0.30 pg/ml, Anti-NPFF: 5.83+/-0.46 pg/ml, p < 0.01). Anti-NPFF did not cause significant change in plasma osmolality, plasma volume or arterial blood pressure. This evidence indicates that endogenous NPFF might be physiologically involved in osmoregulation of the plasma AVP level through its inhibitory action.

Amino Acid Sequence↗
PubMed1998

Evidence that immature rat liver is capable of participating in steroidogenesis by expressing 17alpha-hydroxylase/17,20-lyase P450c17.

Steroid hydroxylase cytochrome P450c17 has been previously purified from microsomal fractions of immature rat livers. In this study, we investigated the expression of P450c17 in rat livers to understand a role of steroidogenesis in the extrasteroidogenic tissue. Upon immunoblot analysis utilizing liver microsomes from rats, P450c17 was detected in 1 and 3 week old rats but not in adult rats. Data from immunohistochemical studies also showed a similar age-dependent expression of P450c17 and indicated that P450c17 detected in immature rat livers is localized in cells surrounding interlobular veins. This age-dependent expression of P450c17 in rat livers was observed in both sexes. Upon enzymatic analysis utilizing microsomal fractions from livers, levels of 17alpha-hydroxylase and 17,20-lyase activity for pregnenolone and progesterone increased by 3 weeks and dramatically reduced at 7 weeks, which is consistent with the expression level of P450c17. These data clearly indicate that P450c17 is expressed in immature rat liver to produce 17alpha-hydroxysteroids and C19-steroids. Based upon immunoblot analysis, the expression level of P450c17 in immature rat livers was approximately one third of that in testis. Compared expression level of P450c17 and total volume of organs between liver and testis, the total amount of steroid metabolites produced by liver P450c17 could be greater than that produced by gonadal P450c17. Because of the absence of P450c17 in rat adrenal glands, rat liver could be the major site for producing 17alpha-hydroxysteroids and C19-steroids in this particular period of life. Although physiological products formed by P450c17 in liver and their roles remain to be elucidated, this study suggests a large capacity of prepubertal rat liver for participating the production of steroid hormones and a putative importance of 17alpha-hydroxysteroids and C19-steroids, such as cortisol and androstendione, which are generally believed to be minor components of steroid hormones in rodents.

Animals↗