Biomedical subjects

H Yokoi

Publications and source records attributed to H Yokoi.

At least 73 records · Page 4Linked to original sources

PubMed1998

Sonochemical polymerization of benzene derivatives: the site of the reaction.

Sonochemical polymerization of benzene and halogen-substituted benzenes has been studied. The difference of absorption spectra of polymerization products can be explained qualitatively using bond energies of the primary products. The relative rate constant of the polymerization reaction is apparently proportional to the inverse of the vapour pressure of the liquids. Using this relation, we analysed the relative rate constant of the polymerization in benzene/chrolobenzene mixtures. From this, we conclude that sonochemical polymerization proceeds in the vapour phase of a bubble.

Journal Article↗

PubMed1998

Steroid 5alpha-reductase type 1 immunolocalized in the rat peripheral nervous system and paraganglia.

Steroid 5alpha-reductase is an enzyme that converts a number of steroids with a C-4, 5 double bond and C-3 ketone to 5alpha-reduced metabolites. This enzyme has been suggested to play a role in brain development and myelination in the rat nervous system. In the present study, we examined the cellular and subcellular localization of the enzyme immunocytochemically in the rat peripheral nervous system and paraganglia using a polyclonal antibody against rat 5alpha-reductase type 1. Light and electron microscopical studies localized 5alpha-reductase in the Schwann cells of myelinated and unmyelinated nerve fibres, the satellite cells of the ganglia, the enteric glial cells and the supporting/sustentacular cells of the paraganglia. In the myelinated nerve fibres, immunoreactivity was observed in the outer loops, the nodes of Ranvier and the Schmidt-Lanterman incisures. Subcellularly, the immunoreactivity was localized in the cytoplasm of various glial cells. No immunoreactivity was observed in the myelin membrane, the axon or the neuronal perikaryon. These findings suggest that 5alpha-reductase is widely distributed in glial cells, and that, in addition to myelination, 5alpha-reduced steroids play a role in some glial functions in the peripheral nervous system.

Animals↗

PubMed1998

The effects of a thromboxane A2 synthesis inhibitor and a prostaglandin I2 analogue on experimental acute necrotizing pancreatitis in rats.

To elucidate the role of thromboxane A2 (TxA2) and prostaglandin I2 (PGI2) in acute necrotizing pancreatitis (ANP) in rats and to determine the effect of the TxA2 synthesis inhibitor OKY-046 and the PGI2 analogue OP-2507, the levels of two prostanoids (TxB2, 6-keto PGF1alpha) and two types of phospholipase A2 (PLA2) activity (cytosolic and secretory) were measured in plasma and three tissues (pancreas, lung, and kidney) after injection of a mixed solution of 5% sodium taurocholate and 0.1% trypsin into the pancreatic duct to induce ANP. The survival rate 24 h after inducing ANP was 33.3% in the nontreated group, versus 83.3 and 58.3% in the groups treated with OKY-046 and OP-2507, respectively. Only the group treated with OKY-046 showed significant improvement compared with the nontreated group. The plasma, pancreatic, and pulmonary TxB2 levels decreased significantly in the group treated with OKY-046, and the histopathological changes were not as severe. The levels of pancreatic and pulmonary cytosolic PLA2 activities decreased, and plasma and pancreatic secretory PLA2 activities also decreased. In conclusion, the levels of both types of PLA2 activity and TxA2 production decreased, and the survival rate improved as a result in the group treated with OKY-046, but OP-2507 had no effect on ANP. TxA2 and two types of PLA2 activity play an important role in the process of aggravation of acute pancreatitis.

6-Ketoprostaglandin F1 alpha↗

PubMed1998

A case of inflammatory pseudotumor of the liver causing elevated serum CA19-9 levels.

Inflammatory pseudotumor of the liver is a rare lesion characterized by proliferating fibrovascular tissue admixed with inflammatory cells. A 50-yr-old Japanese man was hospitalized because of upper abdominal pain and high fever. Computed tomography revealed a poorly demarcated, low density mass in the left lobe of the liver, and abnormal laboratory findings included WBC 9340/mm3, CRP 10.5 mg/dl, and marked elevation of CA19-9 to 1167.9 U/ml. Endoscopic retrograde cholangiography showed irregularity of the intrahepatic bile duct of the left lateral segment, and the lateral segmental branches of the portal vein were not visualized on the venous phase of abdominal angiography. Ultrasound-guided liver biopsy was performed, but malignant disease, including intrahepatic cholangiocarcinoma, could not be completely ruled out. The patient underwent left hepatic lobectomy with lymph node dissection. Histopathological examination yielded a definitive diagnosis of inflammatory pseudotumor. The lesion was immunohistochemically stained for CA19-9 by the ABC method, and the biliary epithelium in severely inflamed portal canals was found to be positive. The markedly elevated preoperative level of CA 19-9 decreased to almost within the normal range and the patient remains well 2 yr 9 months after surgery, without any complications.

Angiography↗

PubMed1998

Regulation of vasopressin synthesis and release by area postrema in rats.

There is evidence indicating that the area postrema (AP), the most caudal circumventricular organ located on the dorsal surface of the medulla, is involved in several physiological regulations. In this study, we investigated the role of AP in the regulation of arginine vasopressin (AVP) synthesis and release, using rats of which the AP was lesioned 6 weeks previously. The level of plasma AVP in the AP lesioned (APX) group was significantly lower than in the sham operated (Sham) group in the basal state. AVP release induced by either hyperosmolality or hypovolemia was significantly attenuated by APX. To clarify the role of AP in AVP synthesis in the hypothalamus, we examined the AVP gene expression using in situ hybridization. AVP messenger RNA levels in paraventricular (PVN) and supraoptic nuclei (SON) in the APX group were significantly lower than in the Sham group in the basal state. Moreover, the AVP messenger RNA levels in PVN and SON in the APX group were also significantly lower than in the Sham group after water deprivation for 3 days. These results suggest that AVP synthesis and release are tonically stimulated by AP in the basal state and that AVP synthesis and release in stimulated states are also regulated, at least partially, by AP.

Animals↗

PubMed1998

Vectorcardiographic evaluation of myocardial infarct size: departure parameters are superior to conventional spatial parameters.

To determine whether the departure parameters derived from a "departure loop" of a vectorcardiogram are more accurate than conventional spatial parameters in evaluating myocardial infarct size, 74 patients with first-onset myocardial infarction (MI) were studied. The correlation between the departure parameters (amplitudes in scalar leads of the departure loop) and the percent defect volume of thallium myocardial scintigrams (%DV) was compared with that of the spatial parameters (magnitude, azimuth, and elevation of the original QRS loop). In anteroseptal MI, the amplitude of a 20-msec vector in the z-axis and the azimuth of a 30-msec vector (H30) were significantly correlated with %DV (r=0.783, p<0.001 and r=0.572, p<0.05). In anteroseptal MI with involvement of the lateral wall, the amplitude of a 30-msec vector in the x-axis and H30 showed significant correlation with %DV (r=0.802, p<0.001 and r=0.772, p<0.01). In inferior and inferoposterior MI, the amplitude of a 30-msec vector in the y-axis and the elevation of a 30-msec vector were significantly correlated with %DV (r=0.920, 0.891, p<0.001 and r=0.871, 0.678, p<0.01, respectively). In conclusion, the departure parameters are more accurate than the spatial parameters for evaluation of myocardial infarct size.

Aged↗

PubMed1998

[The role and expression of CD27/CD70 in tonsil].

We studied the expression and function of CD27 and CD70, which are reported to play an important role in the T-B cell interaction in tonsillar lymphocytes of patients with chronic tonsillitis. In comparison of CD27 and CD70 in peripheral lymphocytes of each patients, no significant difference was found. Furthermore, CD27 and CD70 in T-B cell interaction and antibody production in the tonsil was studied. Our findings was confirmed that CD27 and CD70 are involved in interactions between T/T, T/B and B/B cells. A comparative study of CD27- CD4+ cells and CD70+ CD4 cells, so-called memory cells in the T cell subset, was made in tonsillar lymphocytes and peripheral lymphocytes. No significant difference was found in the presence of CD27+ CD4+ cells, but the CD27- CD4+ cells increased in tonsillar lymphocytes. This suggests recurrent antigenic stimulation and the presence of memory cells in tonsillar lymphocytes. Localization of CD27 and CD70 in tonsillar tissue was also investigate.

Antibody Formation↗

PubMed1998

High level of lipoprotein(a) is a strong predictor for progression of coronary artery disease.

Elevated levels of serum lipoprotein(a) [Lp(a)] are reported to be associated with risk of atherosclerosis and thrombosis. Little is known about the influence of Lp(a) on the progression of coronary artery disease. We evaluated the association of serum Lp(a) and the long-term changes of angiographic severity in patients who underwent repeated coronary angiography at intervals of more than 2 years. We evaluated 70 patients, and divided them into 3 groups by angiographic findings. Median Lp(a) concentration was significantly higher in the progression group (N=36) than in the no-change group (N=23) or the regression group (N=11) (32.4 vs 22, 19.3 mg/dl, p<0.05). Furthermore, the progression group had more patients whose Lp(a) levels were greater than 30 mg/dl (p=0.006), while in the regression group all patients were under 30 mg/dl. Stepwise logistic regression analysis for progression of lesions showed that Lp(a) > or =30 mg/dl remained significant, giving an estimated odds ratio (OR) of 2.46 (p= 0.005). In the subgroup analysis, OR in patients with mild lesions was reduced to 2.05 (p<0.05) while in patients with severe lesions OR was increased to 3.39 (p=0.003). The serum Lp(a) level has a close correlation with angiographic progression, and may be an important predictor for progression.

Aged↗

PubMed1998

Initial Experience with the ACS Multi-Link Stent: Serial Angiographic Follow-Up and Comparison with the Palmaz-Schatz Stent in Matched Lesions.

To evaluate the efficacy of the more flexible ACS Multi-Link stent, a prospective angiographic follow-up study was performed. Implantation of the ACS Multi-Link stent was attempted in 70 consecutive patients with 79 coronary lesions from April to November 1995. Clinical success defined as final % diameter stenosis of < 50% without death, bypass surgery or Q-wave myocardial infarction was achieved in 95% of the patients. There was 1 in-hospital death due to acute pulmonary embolism. In-hospital subacute stent occlusion occurred in 2 cases. Follow-up angiograms were obtained in 62 (83%) eligible lesions. The minimal luminal diameter improved from 0.97 +/- 0.41 to 2.72 +/- 0.30 mm, but started to decrease at 1 month (2.38 +/- 0.42 mm), and continued to decrease throughout the 6 months (1.96 +/- 0.41 mm). Angiographic restenosis (stenosis ³ 50%) occurred in 16% of the lesions, a rate smaller though not significantly different from the 25% with the Palmaz-Schatz stent. A revascularization procedure of the target lesion was required in 6% of the patients. Multivariate analysis identified lack of post-dilatation, type of lesion, lesion length and pre-procedural reference diameter to be predictors of angiographic restenosis. In conclusion, the ACS Multi-Link stent can be implanted successfully with a low complication rate and a clinical outcome at least comparable to the Palmaz-Schatz stent.

Journal Article↗

PubMed1998

Initial Experience with the ACS MultiLink Stent: Serial Angiographic Follow-up and Comparison with the Palmaz-Schatz Stent in Matched Lesions.

To evaluate the efficacy of the more flexible ACS Multi-Link stent, a prospective angiographic follow-up study was performed. Implantation of the ACS Multi-Link stent was attempted in 70 consecutive patients with 79 coronary lesions from April to November 1995. Clinical success defined as final % diameter stenosis of < 50% without death, bypass surgery nor Q wave myocardial infarction was achieved in 95% of the patients. There was 1 in-hospital death due to acute pulmonary embolism. In-hospital subacute stent occlusion occurred in 2 cases. Follow-up angiograms were obtained in 62 (83%) eligible lesions. The minimal luminal diameter improved from 0.97 +/- 0.41 to 2.72 +/- 0.30 mm, but started to decrease at 1 month (2.38 +/- 0.42 mm), and continued to decrease throughout the 6 months (1.96 +/- 0.41 mm). Angiographic restenosis (stenosis ³ 50%) occurred in 16% of the lesions, a rate smaller though not significantly different from the 25% with the Palmaz-Schatz stent. A revascularization procedure of the target lesion was required in 6% of the patients. Multivariate analysis identified lack of post-dilatation, type of lesion, lesion length and pre-procedural reference diameter to be predictors of angiographic restenosis. In conclusion, the ACS Multi-Link stent can be implanted successfully with a low complication rate and a clinical outcome at least comparable to the Palmaz-Schatz stent.

Journal Article↗

PubMed1998

Decreased expression of cold-inducible RNA-binding protein (CIRP) in male germ cells at elevated temperature.

Physiological scrotal hypothermia is necessary for normal spermatogenesis and fertility in mammals. Cirp is a recently identified cold-inducible RNA-binding protein that is inducible at 32 degrees C in mouse somatic cells in vitro. Cirp is constitutively expressed in the testis of mouse and structurally highly similar to RBM1, a candidate for the human azoospermia factor. To elucidate the role played by Cirp in spermatogenesis, we investigated its expression levels during spermatogenesis and after heat stress. In the mouse testis, cirp mRNA was detected in the germ cells, and the level varied depending on the stage of differentiation. Also, a high level of Cirp protein was detected immunohistochemically in the nucleus of primary spermatocytes. Expression of Cirp was decreased in the GC-2spd(ts) mouse germ cell line when culture temperature was raised from 32 degrees C to 37 degrees C. When mouse testis was exposed to heat stress by experimental cryptorchidism or immersion of the lower abdomen in warm (42 degrees C) water, the expression of Cirp was decreased in the testis within 6 hours after either treatment. In human testis with varicocele analyzed immunohistochemically, germ cells expressed less Cirp protein than those in the testis without varicocele. These results demonstrated that CIRP expression is down-regulated at elevated temperature in male germ cells of mice and humans. Analysis of Cirp expression in the testes will help elucidate the molecular mechanisms leading to male infertility.

Adult↗

PubMed1998

Light and electron microscopic immunocytochemistry on the localization of 17 alpha-hydroxylase/C17,20-lyase (P450c17) in the rat placenta.

The rat placenta is the primary source of androgens during the second half of pregnancy. Androgens are converted to estrogens in the ovaries and contribute to the maintenance of normal pregnancy. We immunocytochemically characterized the cellular and subcellular localization of cytochrome P450 of 17 alpha-hydroxylase/C 17,20-lyase (P450c17), an enzyme responsible for androgen synthesis, in the rat placenta. We also observed the fine structure of the placenta by electron microscopy. The rat placenta had a different structure from the primate, and contained four zones: labyrinth, basal zone, decidua basalis, and metrial gland. The labyrinth had three trophoblastic layers and fetal endothelium, and P450c17 immunoreactivity was homogeneously localized in the three trophoblastic layers but not in the fetal endothelium. In the basal zone, various types of trophoblasts were observed, and the immunoreaction was localized in small basophilic cells and giant cells. The intensity of staining was heterogeneous among these cells. The decidua basalis showed no immunostaining. Subcellular localization of the enzyme was in the cytoplasm, but not in the nucleus or mitochondria. The present study demonstrated a steroidogenic potency in both the labyrinth and the basal zone, although it was shown only in the basal zone in previous studies.

Animals↗

PubMed1998

[A case of spontaneous hemopneumothorax occurred after thoracic drainage].

A 21-year-old man; complaining of left chest pain and dyspnea, was admitted to our hospital with a diagnosis of spontaneous pneumothorax. Though chest X-ray on admission did not show hemothorax, chest drainage revealed intrapleural bleeding. As chest X-ray on the following day showed evident fluid level, emergency operation was carried out with a diagnosis of spontaneous hemopneumothorax. Bleeding point was a ruptured vessel between parietal pleura and bulla in apex of lung. The bulla was resected following hemostasis. After improvement of complicating postoperative re-expansive pulmonary edema, the patient was discharged on the 18th postoperative day. On treatment of spontaneous hemopneumothorax, existence of such a case as ours should be taken into account.

Adult↗

PubMed1998

[PTCA for acute coronary syndrome].

The use of intravenous thrombolytic therapy have revolutionized the medical management of acute MI, prolonging survival and preserving LV function. Yet, despite these important beneficial effects, many deficiencies exist, such as the fewer lytic eligible patients, the low rate of complete reperfusion and high incidence of recurrent Ischemia and intracranial hemorrhage. To improve on these deficiencies, several PTCA strategies for acute MI have emerged, including primary PTCA, rescue PTCA, immediate PTCA, and delayed PTCA. If skilled intervention-list and cath lab team are available, the optimal reperfusion strategy is primary PTCA. If a cath lab is not available and the patient is eligible for thrombolysis, intravenous thrombolytic therapy should be administered. Nevertheless, PTCA still has significant limitations, including complex lesion morphology and restenosis. Preliminary experience support the feasibility and safety of coronary stenting in the setting of acute MI. A randomized trial using the heparin-coated Palmaz-Schatz stent for primary stenting in MI is ongoing. Until a randomized trial data are available, we recommend stenting for provisional stenting.

Acute Disease↗

PubMed1998

[Elevated levels of plasma homocysteine related to saphenous vein graft disease after coronary artery bypass graft surgery].

Elevated levels of plasma homocysteine may be an independent risk factor for coronary atherosclerosis. This study investigated whether plasma homocysteine levels are related to atherosclerotic lesions of saphenous vein grafts after coronary artery bypass surgery. Homocysteine levels were measured in fasting plasma by high-performance liquid chromatography and total cholesterol, triglyceride, high density lipoprotein cholesterol and lipoprotein (a) were also evaluated in 40 patients (mean age 65 +/- 8 years, mean interval after bypass surgery: 6.1 +/- 3.1 years, range 1-13 years). The vein graft disease group was defined as patients with angiographical stenosis of > or = 50% in any vein graft (n = 23). The other patients were defined as the no-vein graft disease group (n = 17). Patients who had a history of chronic renal failure or anatomic lesions of saphenous vein grafts were excluded. The distributions of homocysteine were skewed. Median homocysteine levels were 11.9 nmol/ml in all subjects. Homocysteine levels in the vein graft disease group were significantly higher than in the no-vein graft disease group (median 15.1 vs 10.6 nmol/ml, p = 0.01). In the analysis of plasma lipids, high-density lipoprotein cholesterol levels were significantly lower in the vein graft disease group than in the no-vein graft disease group (mean 37 +/- 11 vs 48 +/- 13 mg/dl, p = 0.01). Multiple regression analysis showed that elevated levels of homocysteine were an independent risk factor for saphenous vein graft disease after coronary artery bypass surgery. These findings indicate that elevated levels of plasma homocysteine are related to atherosclerotic lesions of saphenous vein grafts after coronary artery bypass surgery as well as coronary atherosclerosis.

Aged↗

PubMed1997

Cloning and characterization of human CIRP (cold-inducible RNA-binding protein) cDNA and chromosomal assignment of the gene.

Cold stress induces in microorganisms the synthesis of several proteins that are involved in various cellular processes such as transcription, translation and recombination. Recently, the cold-inducible RNA-binding protein (Cirp) was found to be induced in rodent cells by mild cold stress (32 degrees C). Cirp consists of an N-terminal RNA-binding domain and a C-terminal Gly-rich domain, and plays an essential role in cold-induced suppression of cell proliferation. We report here the cloning of a cDNA encoding an 18-kDa protein with 95.3% identity in an amino-acid sequence to that of mouse Cirp. The human CIRP gene has been mapped to the chromosomal locus 19p13.3 by fluorescence in-situ hybridization. CIRP mRNA is constitutively expressed in all cell lines examined, including K562, HepG2, NC65, HeLa, T24, and NEC8 cells. In all of them, the levels of CIRP mRNA and protein were increased within 12 h after a temperature down-shift from 37 degrees C to 32 degrees C. These results demonstrated that CIRP is a cold-shock protein in human cells. Identification of CIRP may provide a clue to the regulatory mechanisms of cold responses in human cells.

Amino Acid Sequence↗

PubMed1997

Interventional treatment for children with severe coronary artery stenosis with calcification after long-term Kawasaki disease.

BACKGROUND: About 4% of children with Kawasaki disease (KD) eventually develop ischemic heart disease, which is often associated with calcified stenosis. We assessed the utility of the percutaneous transluminal coronary rotational ablation (PTCRA) in children with coronary artery stenosis after KD. METHODS AND RESULTS: Four children (three boys and one girl; age, 12 to 13 years) with coronary artery stenosis underwent percutaneous transluminal coronary angioplasty (PTCA) and PTCRA 11.8+/-0.9 years after the onset of KD. Morphology of the coronary artery wall was evaluated by intravascular ultrasound imaging. In one patient, the targeted lesion for intervention was in the left anterior descending artery (90% stenosis); in the other three patients, it was in the middle of the right coronary artery (75% to 90% stenosis). PTCA failed in three patients because of severe stenosis with calcification. However, PTCRA proved effective, with stenosis rates reduced from 90% to 25%. Follow-up coronary angiography performed 4 months after the procedure demonstrated no restenosis, but mild aneurysms occurred in two patients. CONCLUSIONS: This study suggests that PTCRA is useful for revascularizing coronary arteries with severe stenosis and calcification as long-term sequelae of KD. Intravascular ultrasound imaging is useful in assessing the coronary artery wall pathology and in selecting the best treatment intervention.

Adolescent↗

PubMed1997

Increased transcript level of RBM3, a member of the glycine-rich RNA-binding protein family, in human cells in response to cold stress.

Although the cold-shock responses of microorganisms have been extensively investigated, those of mammalian cells are just beginning to be understood. Recently, CIRP, a member of the glycine-rich RNA-binding protein (GRP) family, has been identified as the first cold-shock protein in mammalian cells. Here, we report that RBM3, another member of the GRP family, is induced in human cells in response to cold stress (32 degrees C). RBM3 transcripts were constitutively expressed in all cell lines examined including K562, HepG2, NC65, HeLa, and T24 cells. In all of them, the transcript levels of RBM3 were increased at 24 h after the 37 to 32 degrees C temperature down-shift. In NC65 cells, the kinetics of RBM3 induction was different from that of CIRP. Protein synthesis inhibitors cycloheximide and puromycin induced RBM3 transcripts, but cadmium chloride, H2O2, ethanol, and osmotic shock had no effect. Combined with the different tissue distribution of expression, these results suggest that RBM3 and CIRP play distinct roles in cold responses of human cells.

Carcinoma, Hepatocellular↗