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Biomedical subjects

S Shimizu

Publications and source records attributed to S Shimizu.

At least 289 records · Page 16Linked to original sources

Tissue response of a small saccular aneurysm after incomplete occlusion with a Guglielmi detachable coil.

A 49-year-old woman had a small saccular aneurysm that was incompletely occluded with a Guglielmi detachable coil (GDC). She died from rupture of another aneurysm 42 days after the treatment. Autopsy for the embolized aneurysm revealed no neoendothelium at the aneurysmal neck, but an organized thrombus was observed limited to the periphery of the aneurysmal lumen. Although isolation of the aneurysm was not apparent, loose embolization with this method may help to reinforce the aneurysmal wall.

Aneurysm, Ruptured↗

[Estimation of left internal thoracic artery flow reserve after coronary artery bypass grafting using Doppler flow wire].

The usefulness of the left internal thoracic artery (LITA) for aortocoronary bypass grafting is now established. Reports of variation in LITA graft function are rare. Graft flow was measured using a Doppler flow wire to estimate graft function in 27 patients (24 males, 3 females) who underwent LITA grafting to the left anterior descending artery. Patients were classified into the following 3 groups: Group A consisted of 9 patients with normal left ventricular function and no native flow; Group B consisted of 11 patients with normal ventricular function and good native flow; Group C consisted of 7 patients with abnormal left ventricular function and no native flow. LITA graft function was also estimated 1 year after operation in 12 of these 27 patients (4 in each group). Diastolic/systolic velocity ratio (DSVR) and flow reserve were determined in the proximal, middle, and distal portions of the LITA graft and native left anterior descending artery before and after papaverine administration (8-10 mg). DSVR was significantly higher in the distal portion than in the proximal portion (p < 0.01), but this value did not change after papaverine administration. After 1 year, DSVR in the proximal portion was significantly higher in Group C than in Groups A or B (p < 0.05 for both). Four weeks after operation, the flow reserve of the distal portion was significantly higher in Group A than in Group C (p < 0.001). After 1 year, this value was significantly higher in Group A than in either Groups B or C (p < 0.01, p < 0.001, respectively). The rate of increase in flow reserve in the distal portion was significantly greater in Group A (23.4%) than in groups B (2.53%) or C (1.94%; p < 0.05 for both). The distal portion of the LITA was the best measurement site, since the flow pattern in the LITA graft varied throughout all portions. Diastolic flow velocity in the LITA graft was dominant in patients with myocardial damage. The results indicate that flow reserve of the LITA graft depends on antegrade native coronary flow and distal myocardial damage.

Coronary Artery Bypass↗

Ecotropic viral integration site-1 is activated during, and is sufficient for, neuroectodermal P19 cell differentiation.

Expression of the ecotropic viral integration site-1 (Evi1) proto-oncogene during murine embryonal development is observed by in situ hybridization in primary head folds and neural crest-derived cells associated with the peripheral nervous system and embryonic mesoderm. To elucidate whether expression of Evi1 is involved in early neuroectodermal or mesodermal differentiation, we used murine embryonal carcinoma P19 cells as a model for the study of early embryonic differentiation. After retinoic acid (RA) treatment with aggregation, expression of Evi1 was detected during neural differentiation in P19 cells. However, Evi1 was not expressed in P19 cells during mesodermal differentiation after DMSO treatment with aggregation. Enforced expression of Evi1 in P19 cells induced neuron-specific microtubule-associated protein-2 microtubule-associated protein-2 and TrkA expression in the absence of RA under monolayer culture. After incubation with RA with aggregation, the Evi1 clones expressed microtubule-associated protein-2 continuously but did not express glial fibrillary acidic protein as an astrocyte marker protein until 12 days of culture. Thus, the overexpression of Evi1 leads to neural differentiation of P19 cells and blocks further differentiation into astrocytes by RA treatment, suggesting that Evi1 might be an important transcription factor for regulation of early neuroectodermal differentiation.

Animals↗

Hypoxia and alkalinization inhibit endothelium-derived nitric oxide but not endothelium-derived hyperpolarizing factor responses in porcine coronary artery.

We investigated the mechanisms by which hypoxia and alkalinization inhibit the endothelium-dependent relaxation to Substance P (SP) in porcine coronary artery. In a KCl contracture, the major component of the SP response is endothelium-derived nitric oxide (EDNO), whereas with receptor-mediated 9,11-dideoxy-llalpha, 9alpha-epoxymethanoprostaglandin F(2alpha) (U46619) stimulation, the SP response is dependent on both EDNO and endothelium-derived hyperpolarization factor. Intracellular alkalinization by NH(4)Cl reduced the peak of SP responses when arteries were contracted with KCl, whereas with U46619 stimulation, the peak was little effected but the duration was shortened. In endothelial cell-denuded arteries, alkalinization with NH(4)Cl shifted the sodium nitroprusside concentration-relaxation relations rightward. The effects of NH(4)Cl in SP- and sodium nitroprusside-induced relaxations were attenuated by decreasing extracellular pH (pH(o)) from 7.4 to 7.2, which normalized intracellular pH (pH(i)) to control levels. In contrast, in U46619 contractures, the SP response in the presence of a NO synthase inhibitor was unaffected by NH(4)Cl. Moreover, hypoxia blunted but did not abolish the responses to SP for U46619 contractures; addition of KCl, however, abolished the SP response under hypoxia. Endothelial [Ca(2+)](i) was measured with fura-2 differentially loaded only into endothelial cells on intact arteries. Despite the attenuation of the SP response in KCl contractures by NH(4)Cl or hypoxia, endothelial [Ca(2+)](i) responses were unchanged. Our results suggest that hypoxia and alkalinization inhibit EDNO but not endothelium-derived hyperpolarization factor relaxations through a mechanism(s) not involving endothelial cell [Ca(2+)](i). Inhibition of EDNO relaxation by alkalinization with NH(4)Cl is likely to occur at the level of activation of guanylate cyclase and/or at a step downstream in smooth muscle.

Ammonium Chloride↗

Synthesis of Giant Zeolite Crystals by a Bulk-Material Dissolution Technique.

Using a quartz glass tube as a bulk silica source under aqueous hydrothermal conditions afforded giant crystals of MFI zeolite about 3 mm in size (see photo). Similar procedures were successfully applied to bulk aluminosilicate ceramics to synthesize large crystals of other zeolites, such as ANA, JBW, CAN, and SOD.

Journal Article↗

[An old man presenting with fluctuating bilateral multiple cranial nerve palsies and positive test for perinuclear antineutrophil cytoplasmic antibody].

A 70-year-old man admitted to a local hospital because of facial muscle weakness, tinnitus and facial pain in left side, was then given corticosteroid with a tentative diagnosis of Bell's palsy and his symptoms gradually improved. Since these symptoms recurred six months later, he was referred to our neurological service. As his brain CT revealed diffuse thickening and enhancement of the dura mater, he was thought to have hypertrophic pachymeningitis (HP). Intravenous antibiotics were started for aspiration pneumonia and his neurological symptoms gradually improved. HP caused by bacterial infection was thus likely and antibiotics, rifampicin and metronidazole, were administered orally as an outpatient. However, one month later, these symptoms were worsened with headache and double vision. He was then rehospitalized. MR imagings of the head with gadolinium disclosed diffuse meningeal thickening and enhancement, especially of the left-sided cerebellar tentorium. Erythrocyte sedimentation rate and C-reactive protein were moderately elevated. Serum angiotensin converting enzyme was within normal range. The test for cytoplasmic antineutrohil cytoplasmic antibody (ANCA) in the serum was negative, however, that for perinuclear ANCA was positive at a titer of 99 EU. Lumbar puncture showed normal findings and negative culture results for bacteria, fungi or mycobacteria. Dural biopsy specimens showed non-specific granulomatous inflammation of the dura with epithelioid histiocytes and Langerhans type multinuclear giant cells with caseous necrosis, however, with no presence of fungi or tubercle bacilli. After the oral administration of cyclophosphamide (100 mg, daily) and prednisolone (40 mg, daily), his neurological symptoms and laboratory findings have been gradually improved and he is well one year after discharge. This case together with previous reports suggests that ANCA positive HP without evidence of other organ involvements may belong to the limited form Wegener's granulomatosis. In the literatures of idiopathic HP, the treatment effect with corticosteroid alone is initially favorable, but transient. On the other hand, using the combined therapy of cyclophosphamide and prednisolone, the remission has been achieved in more than 90% of patients with WG. These data suggest that P-ANCA positive HP should be treated with a combination of corticosteroid and cyclophosphamide.

Aged↗

[The relationship between the histopathological atypia and expression of beta-catenin in colonic neoplasms resected by endoscopy; comparison with that of p53 protein].

Previous studies have reported predominantly nuclear localization of beta-catenin as a role for colorectal carcinogenesis. In this study, we examined the immunohistochemical expression of beta-catenin and p53 protein in 90 colonic neoplasms {33 carcinomas in adenoma (CIA), 28 high grade adenomas and 29 low grade adenomas}, resected by colonic endoscopy. Out of 33 CIAs. 28 (84.8%) cases showed predominantly nuclear localization of beta-catenin, and that was significantly higher than those of both high grade (46.4%) and low grade (13.8%) adenomas. The positiveness of p53 expression in CIAs was 51.5% (17/33), while 17.9% in high grade and 3.4% in low grade adenomas. However, there was no correlation between both protein expressions (p = 0.3472, chi 2 test). The results suggests that nuclear localization and accumulation of beta-catenin is earlier event than that of p53 mutation in adenoma-carcinoma sequence, and is useful as a marker in histopathological diagnosis for malignant conversion as well as p53.

Adenoma↗

[Nicotinic acid and nicotinamide].

Nicotinic acid and nicotinamide are called niacin. They are the antipellagra vitamin essential to many animals for growth and health. In human being, niacin is believed necessary together with other vitamins for the prevention and cure of pellagra. Niacin is widely distributed in nature; appreciable amounts are found in liver, fish, yeast and cereal grains. Nicotinamide is a precursor of the coenzyme NAD and NADP. Some of the most understood metabolic processes that involve niacin are glycolysis, fatty acid synthesis and respiration. Niacin is also related to the following diseases: Hartnup disease; blue diaper syndrome; tryptophanuria; hydroxykynureninuria; xanthurenic aciduria; Huntington's disease.

Humans↗

[Pantothenic acid].

Pantothenic acid is the antipellagra vitamin essential to many animals for growth and health. It is widely distributed in nature; appreciable amounts are found in liver and some microorganisms. Bound forms of pantothenic acid, such as coenzyme A and 4'-phosphopantetheine, play important roles in various metabolic processes, especially, in fatty acid synthesis and degradation.

Animals↗

[Elderly dyserythropoietic anemia first diagnosed after presentation of hemorrhagic gastric ulcer].

A 71-year-old man presented with epigastralgia and tarry stool. Laboratory examination showed anemia (Hb 7.1 g/dl) due to hemorrhagic gastric ulcer and positive Coombs' test without features of hemolysis. Initial bone marrow smears disclosed normal granulocytes and megakaryocytes, but only erythroid hyperplasia with multinuclearity and megaloblastosis was identified. Cytogenetic studies revealed normal karyotype. Congenital dyserythropoietic anemia (CDA) type II was initially suspected. Serologically, however, acid hemolysis and anti-I * i tests were negative as were the results of another Coombs' test. The second bone marrow aspiration disclosed a marked decrease in multinucleated erythroblasts together with an increase in those that had internuclear chromatin bridges. Electron microscopy of bone marrow specimens demonstrated morphological features of CDA types I and II, thus yielding a final diagnosis of elderly dyserythropoietic anemia, which is similar to both CDA types. It was suggested that the reactive secretion of erythropoietin due to bleeding played a role in these pathologic changes.

Aged↗

[Sequential changes in hormone levels in postmenopausal breast cancer patients under long-term treatment with an aromatase inhibitor. Kanagawa AI Study Group].

Sequential changes in hormone levels were assessed for one year in postmenopausal breast cancer patients administered the aromatase inhibitor fodrozole hydrochloride hydrate (Afema) in order to evaluate its efficacy and safety in long-term treatment. Forty patients received Afema alone as postoperative adjuvant therapy, while 30 received it with 5-FU. Plasma estrone and estradiol levels decreased significantly in both groups (p < 0.001) and were not affected by body mass index (BMI). Plasma androstenedione and testosterone levels increased within the normal range. Aldosterone levels hit bottom 3 months after treatment was started, and tended to return to the pre-treatment baseline thereafter. Plasma cortisol levels increased significantly within the normal range. FDP and alpha 2-PIPC, parameters related to blood coagulation and fibrinolysis, showed no significant change. Adverse reactions, mainly nausea and elevation of LDH levels, were all slight. Thus, long-term administration of Afema resulted in significant decreases in estrogen levels with few adverse reactions regardless of the BMI, suggesting that it can be safely used as effective postoperative adjuvant therapy.

Aged↗

Positive washing cytology in patients with pancreatic cancer indicates a contraindication of pancreatectomy.

BACKGROUND: Although peritoneal washing cytology has been widely used in the field of gynecology, it has not been performed so frequently in patients with pancreatic cancer. Only a few papers have reported surgical implications of peritoneal washing cytology. MATERIALS AND METHODS: We reviewed results of peritoneal washing cytology performed immediately after laparotomy in 50 Japanese patients with pancreatic cancer. The 50 patients were divided into two groups according to the results of cytology. Clinicopathological findings were compared between these two groups. RESULTS: Cytology of peritoneal washing was positive in 13 (26%) of the 50 patients. Nine of the 13 patients had no visible peritoneal dissemination. There were no significant differences regarding the age, tumor size and serum level of the carcinoembryonic antigen. Moderately to poorly differentiated adenocarcinoma and perineural invasion (ne3) and lymphatic permeation (ly3) of marked degree were more frequent in the positive group than in the negative group (p < 0.01). The survival curve of the 37 patients with negative cytology was significantly better than that of the 13 with positive cytology (p < 0.01). Four of 13 patients with positive cytology underwent a potentially curative resection but died within 12 months. Three of these four patients died of peritonitis carcinomatosa with massive malignant ascites and one died of local recurrence. CONCLUSIONS: Positive peritoneal washing cytology is not rare in patients with pancreatic cancer and indicates a contraindication of pancreatectomy.

Adenocarcinoma↗

Nitrilase catalyzes amide hydrolysis as well as nitrile hydrolysis.

While amides were reported to be completely inert as substrates for all nitrilases reported to date, the nitrilase from Rhodococcus rhodochrous J1, which catalyzes the hydrolytic cleavage of the C-N triple bond in nitrile to form acid and ammonium, was surprisingly found to catalyze hydrolysis of amide to acid and ammonium stoichiometrically. This nitrilase exhibited a Km of 2.94 mM for benzamide, similar to that for benzonitrile as the original substrate (2.10 mM), but the Vmax for benzamide was six orders of magnitude lower than that for benzonitrile. Benzamide inhibited the nitrilase reaction in a reversible, apparently competitive manner. A mutant nitrilase containing alanine or serine instead of Cys165, which is essential for nitrilase catalytic activity, showed no amidase activity. This observation demonstrated that Cys165 plays a crucial role in the hydrolysis of amides as well as nitriles. Together with some reports that certain nitrilases were previously noted to produce low amounts of amide as a by-product from nitrile, the above unexpected findings suggested the existence of a common tetrahedral intermediate in the nitrilase reaction involving nitrile or amide as a substrate.

Aminohydrolases↗

Bcl-2 prevents caspase-independent cell death.

Nitric oxide (NO) is implicated in apoptosis and has both cytotoxic and cytoprotective effects. Exogenous NO induced the death of PC12 and HeLa cells via a process showing features of both apoptosis and necrosis, with chromatin condensation, nuclear compaction, and mitochondrial swelling. Activation of caspases was not observed during NO-induced cell death. In addition, cell death was not inhibited by peptide caspase inhibitors or by expression of p35, a baculovirus-encoded caspase inhibitor, indicating that NO-induced cell death was independent of caspases. NO-induced cell death was enhanced by Bax expression in a caspase-independent manner and prevented by the anti-cell death protein Bcl-2. Although Bcl-2 has previously been shown to prevent cell death by inhibiting caspase activation, these results indicate that it can also prevent cell death via a caspase-independent mechanism.

Adrenal Gland Neoplasms↗

Chiral alcohol synthesis with microbial carbonyl reductases in a water-organic solvent two-phase system.

Production of chiral 4-chloro-3-hydroxybutanoate ethyl esters (CHBE) was performed through microbial asymmetric reduction of 4-chloroacetoacetate ethyl ester (CAAE). The enzymes reducing CAAE to (R)- and (S)-CHBE were found to be produced by Sporobolomyces salmonicolor and Candida magnoliae, respectively. The enzyme of S. salmonicolor is a novel NADPH-dependent aldehyde reductase (AR) belonging to the aldo-keto reductase superfamily. When AR-overproducing Escherichia coli transformant cells or C. magnoliae cells were incubated in an organic solvent-water two-phase system, 300 or 90 mg/mL of CAAE was almost stoichiometrically converted to (R)- or (S)-CHBE (> 92% ee), respectively.

Alcohol Oxidoreductases↗

Bax interacts with the permeability transition pore to induce permeability transition and cytochrome c release in isolated mitochondria.

Cytochrome c release and the mitochondrial permeability transition (PT), including loss of the transmembrane potential (Deltapsi), play an important role in apoptosis. Using isolated mitochondria, we found that recombinant Bax and Bak, proapoptotic members of the Bcl-2 family, induced mitochondrial Deltapsi loss, swelling, and cytochrome c release. All of these changes were dependent on Ca2+ and were prevented by cyclosporin A (CsA) and bongkrekic acid, both of which close the PT pores (megachannels), indicating that Bax- and Bak-induced mitochondrial changes were mediated through the opening of these pores. Bax-induced mitochondrial changes were inhibited by recombinant Bcl-xL and transgene-derived Bcl-2, antiapoptotic members of the Bcl-2 family, as well as by oligomycin, suggesting a possible regulatory effect of F0F1-ATPase on Bax-induced mitochondrial changes. Proapoptotic Bax- and Bak-BH3 (Bcl-2 homology) peptides, but not a mutant BH3 peptide nor a mutant Bak lacking BH3, induced the mitochondrial changes, indicating an essential role of the BH3 region. A coimmunoprecipitation study revealed that Bax and Bak interacted with the voltage-dependent anion channel, which is a component of PT pores. Taken together, these findings suggest that proapoptotic Bcl-2 family proteins, including Bax and Bak, induce the mitochondrial PT and cytochrome c release by interacting with the PT pores.

Animals↗