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Biomedical subjects

Y Imai

Publications and source records attributed to Y Imai.

At least 217 records · Page 12Linked to original sources
PubMed2000

Essential role of Bmp7 (snailhouse) and its prodomain in dorsoventral patterning of the zebrafish embryo.

Bone morphogenetic proteins (Bmps) are signaling molecules that have been implicated in a variety of inductive processes. We report here that zebrafish Bmp7 is disrupted in snailhouse (snh) mutants. The allele snh(st1) is a translocation deleting the bmp7 gene, while snh(ty68) displays a Val->Gly exhange in a conserved motif of the Bmp7 prodomain. The snh(ty68) mutation is temperature-sensitive, leading to severalfold reduced activity of mutant Bmp7 at 28 degrees C and non-detectable activity at 33 degrees C. This prodomain lesion affects secretion and/or stability of secreted mature Bmp7 after processing has occurred. Both snh(st1) and snh(ty68) mutant zebrafish embryos are strongly dorsalized, indicating that bmp7 is required for the specification of ventral cell fates during early dorsoventral patterning. At higher temperature, the phenotype of snh(ty68) mutant embryos is identical to that caused by the amorphic bmp2b mutation swirl swr(ta72) and similar to that caused by the smad5 mutation somitabun sbn(dtc24). mRNA injection studies and double mutant analyses indicate that Bmp2b and Bmp7 closely cooperate and that Bmp2b/Bmp7 signaling is transduced by Smad5 and antagonized by Chordino.

Amino Acid Sequence↗
PubMed2000

Involvement of Iba1 in membrane ruffling and phagocytosis of macrophages/microglia.

Ionized calcium binding adaptor molecule 1, Iba1, is an EF hand calcium binding protein whose expression is restricted to macrophages/microglia. In this study, Iba1 was shown to colocalize with F-actin in membrane ruffles induced by macrophage colony-stimulating factor and in phagocytic cups formed during zymosan phagocytosis. Expression of mutant Iba1 carrying either N- or C-terminal deletions or carrying a substitution in the calcium binding domain, suppressed the membrane ruffling and the phagocytosis. These results indicate that Iba1 is a key molecule in membrane ruffling and the phagocytosis of macrophages/microglia. Furthermore, Iba1 colocalized with a small GTPase Rac in the membrane ruffles and the phagocytic cups. The Iba1 mutants also suppressed membrane ruffling induced by dominant active Rac1V12, but do not affect microspikes by Cdc42V12 and stress fibers by RhoAV14. These observations suggest that Iba1 is involved in Rac and calcium signaling pathways.

Actins↗
PubMed2000

Left cervical aortic arch with aortic coarctation and saccular aneurysm.

Cervical aortic arch is a very rare malformation and is occasionally accompanied by other cardiovascular anomalies. A 48-year-old male patient had a left cervical aortic arch with aortic coarctation and saccular aneurysm distal to the coarcted segment. The major clinical manifestations were upper body hypertension with a 50-mmHg discrepancy between the upper and lower limbs and a loud continuous murmur in the upper chest and back. Magnetic resonance angiography successfully depicted the anomalous aorta, and the aortic coarctation and aneurysm were surgically resected and the thoracic aorta was reconstructed. The discrepancy in blood pressure diminished after the operation, but antihypertensive medication was continued to satisfactorily control the hypertension.

Aorta, Thoracic↗
PubMed2000

Office blood pressure variability as a predictor of brain infarction in elderly hypertensive patients.

Large 24-h blood pressure (BP) variability and an excessive drop in BP during nighttime are associated with a higher risk of cardiovascular events. Data are lacking regarding the prognostic significance of variability in BP measured during office visits. We analyzed the relationship between office BP variability and the risk of brain infarction in elderly patients receiving antihypertensive therapy. Patients who experienced their first-ever stroke at the age of 60 years or over were registered in the study. At least 2 sex- and age-matched control patients were registered for each case patient. Office BP at each clinic visit and known cardiovascular risk factors were recorded. The BP variability was defined as the variation coefficient (VC) of office BP. In this report, we analyze the data of brain infarction patients. The VC of both systolic and diastolic BPs was significantly higher in the brain infarction patients than in the control patients. Higher office BP variability was associated with a higher risk of brain infarction after adjustment for BP level and other confounding factors. Regarding diastolic BP, the association of brain infarction with the maximal value for the difference of office BPs taken at any consecutive two visits (Max-deltaBP) or the difference between the highest and lowest values of office BP (BP-range) recorded during a 1-year period prior to the event was also significant. In conclusion, a retrospective case-control study suggested that office BP variability was an independent predictor of brain infarction. Either the Max-deltaBP or the BP-range may be surrogate indices of diastolic BP variability.

Aged↗
PubMed2000

Detection of Salmonella by using the colorimetric DNA/rRNA sandwich hybridization in microtiter wells.

A rapid and readily available DNA probe kit was developed for the detection of Salmonella spp. This kit utilized the colorimetric DNA/rRNA sandwich hybridization method in microtiter wells. Within 3 hr Salmonella spp. in selective enrichment broth cultures were detected by the DNA probe kit. The kit effectively identified all of 187 strains of Salmonella tested and yielded no false-positive reactions in the examination of 674 pure cultures of non-salmonellae. The DNA probe kit could detect 10(5) cfu/ml in pure culture. A total of 379 naturally contaminated samples (raw chicken meat, liquid egg, animal feeds, poultry feces and frozen foods) were tested, both by the standard culture method and the DNA probe kit. The 169 of these samples were culture positive and 210 were culture negative. The sensitivity of the DNA probe kit was 98.2% (166/169) and the specificity was 99.5% (209/210). These results show that the DNA probe kit is a useful tool to examine a large number of various samples for contamination by Salmonella spp. in food and livestock industry.

Animal Feed↗
PubMed2000

Cryofiltration and oral corticosteroids provide successful treatment for an elderly patient with cryoglobulinemic glomerulonephritis associated with hepatitis C virus infection.

A 75-year-old man was admitted due to nephrotic syndrome, purpura on the legs, which was associated with hepatitis C virus (HCV), and type II mixed cryoglobulinemia. Renal biopsy revealed features of cryoglobulinemic glomerulonephritis. Since the patient was elderly and the HCV genotype was Ib, interferon-alpha for reducing HCV was not indicated. Four sessions of cryofiltration and the administration of corticosteroids improved the proteinuria and renal function strikingly without adverse effects. This case demonstrates that an elderly patient who has nephrotic syndrome caused by cryoglobulinemic glomerulonephritis associated with HCV can be treated safely by cryofiltration with low doses of oral corticosteroids.

Adrenal Cortex Hormones↗
PubMed2000

Isolation and characterization of Na+/Ca2+ exchanger gene and splicing isoforms in mice.

The Na+/Ca2+ exchanger gene NCX1 is ubiquitously expressed in mammalian tissues, and encodes several isoforms through alternative RNA splicing. In this report, we describe the gene structure that gives rise to the multiple isoforms, and the tissue-specific expression of these isoforms in mice. The mouse NCX1 gene contains a cluster of six exons (A, B, C, D, E, and F) which encode a variable region in the large intracellular loop of the protein, as previously reported in rabbits and humans. Using reverse transcription-polymerase chain reaction (RT-PCR), expression of the isoforms was examined in several tissues. We also identified a novel splice variant, which originate from exons A, C, D, and F. These findings provide new insights into the significance of the large repertoire of NCX1 isoforms.

Alternative Splicing↗
PubMed2000

Products of hemolysis in the subarachnoid space inducing spreading ischemia in the cortex and focal necrosis in rats: a model for delayed ischemic neurological deficits after subarachnoid hemorrhage?

OBJECT: The pathogenesis of delayed ischemic neurological deficits after subarachnoid hemorrhage has been related to products of hemolysis. Topical brain superfusion of artificial cerebrospinal fluid (ACSF) containing the hemolysis products K+ and hemoglobin (Hb) was previously shown to induce ischemia in rats. Superimposed on a slow vasospastic reaction, the ischemic events represent spreading depolarizations of the neuronal-glial network that trigger acute vasoconstriction. The purpose of the present study was to investigate whether such spreading ischemias in the cortex lead to brain damage. METHODS: A cranial window was implanted in 31 rats. Cerebral blood flow (CBF) was measured using laser Doppler flowmetry, and direct current (DC) potentials were recorded. The ACSF was superfused topically over the brain. Rats were assigned to five groups representing different ACSF compositions. Analyses included classic histochemical and immunohistochemical studies (glial fibrillary acidic protein and ionized calcium binding adaptor molecule) as well as a terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay. Superfusion of ACSF containing Hb combined with either a high concentration of K+ (35 mmol/L, 16 animals) or a low concentration of glucose (0.8 mmol/L, four animals) reduced CBF gradually. Spreading ischemia in the cortex appeared when CBF reached 40 to 70% compared with baseline (which was deemed 100%). This spreading ischemia was characterized by a sharp negative shift in DC, which preceded a steep CBF decrease that was followed by a slow recovery (average duration 60 minutes). In 12 of the surviving 14 animals widespread cortical infarction was observed at the site of the cranial window and neighboring areas in contrast to findings in the three control groups (11 animals). CONCLUSIONS: The authors conclude that subarachnoid Hb combined with either a high K+ or a low glucose concentration leads to widespread necrosis of the cortex.

Animals↗
PubMed2000

Effects of graded levels of dietary casein and corn oil on total cholesterol and triacylglycerol in plasma and liver of rats.

With the intention of examining the effects of dietary protein and oil levels on total cholesterol (T-CHOL) and triacylglycerol (TG) concentrations in the plasma and liver, male Wistar rats, weighing about 170 g, were fed diets containing graded levels of casein and corn oil for 2 wk. At the 5, 20, and 30% levels of dietary corn oil, plasma T-CHOL concentrations were generally enhanced in proportion to the rise of dietary casein level, but plasma TG contents were scarcely influenced by the level. At the 8 to 35% casein levels, plasma T-CHOL and TG concentrations were the highest at the 5% corn oil level, followed in order by the 20 and 30% levels of oil. At the 5 and 20% oil levels, hepatic T-CHOL contents were hardly changed at the 8 to 30% casein levels, but enhanced at the 35% casein level. At the 30% oil level, the T-CHOL contents tended to be changed proportionally to casein levels. At all levels of casein, hepatic T-CHOL contents tended to be relatively high at the 30% corn oil, middle at the 20% oil, and low at the 5% one. At each corn oil level, TG contents in the liver tended to be elevated at the 8 to 15% casein levels and highly preserved at the 15 to 25% ones. Then, the raised TG contents declined at the 5 and 20% levels of corn oil and remained constant at the 30% oil. At each casein level, the contents of hepatic TG were generally high at the 30% oil level, followed in order by the 20 and 5% oil levels. These results indicated that plasma and liver T-CHOL concentrations were proportionately enhnaced by the increase in casein level, and plasma TG contents were hardly affected by the level and hepatic TG ones were lowered by relatively lower or higher casein level, and the rise in corn oil level generally reduced plasma T-CHOL and TG concentrations, but raised hepatic ones.

Animals↗
PubMed2000

Elution of bisphenol A from composite resin: a model experiment.

To understand the leaching characteristics of bisphenol A (BPA) from composite resins, we prepared experimental composite resins containing known amounts of BPA and examined the BPA elution from the resins in water and methanol at 37 degrees C. The concentration of BPA in each eluate was determined by high performance liquid chromatography. Cumulative BPA release was calculated and plotted against extraction time. The elution of BPA was rapid during a 6-hr period for both solvents, and then declined and continued steadily. Plots of square root of the amount of BPA leached against logarithm of extraction time produced good linear relationships from a 6-hr period thereafter. Extrapolation of the relationship enabled prediction of the amount of BPA to be leached in the long term. The present results suggested that little or no estrogenic effect due to long-term elution of BPA from commercial Bis-GMA-based resins is expected in practice.

Benzhydryl Compounds↗
PubMed2000

Analysis of major components and bisphenol A in commercial Bis-GMA and Bis-GMA-based resins using high performance liquid chromatography.

The purpose of this study was to examine the quality of commercially available Bis-GMA because concerns about Bis-GMA and Bis-GMA-based resins have been recently expressed in dentistry. Four major components and bisphenol A, which is a compound of recent controversy, were quantitatively analyzed using high performance liquid chromatography (HPLC) in three commercial Bis-GMA and six Bis-GMA-based composite resins. The contents of genuine Bis-GMA, Iso-bis-GMA, Bis-GMA-H, and Bis-GMA-M as well as the total content of the four monomers were 45.7-57.5%, 19.9-26.2%, 1.8-5.0%, 0.6-15.0% and 83.7-85.6% in the commercial Bis-GMAs, or 3.8-9.1%, 1.7-4.3%, 0.1-0.5%, 0.1-2.0% and 5.8-14.0% in composite resins, respectively. There were some differences in the composition of the major components between domestic and foreign materials. Bisphenol A contents in the unpolymerized composite resins were 1.5-10.2 micrograms/g resin.

Benzhydryl Compounds↗
PubMed2000

Differential scanning calorimetric study of acrylic resin powders used in dentistry.

The thermal behavior of eight dental acrylic resin powders was studied using differential scanning calorimetry (DSC). In addition, high performance liquid chromatography was performed to supplement the DSC analysis. The HPLC analysis revealed that the contents of residual monomers and benzoyl peroxide (BPO) in the powders were 0.01-0.97 mass% and 0.25-1.28 mass%, respectively. All the resin powders produced one broad exothermic peak, while a mixture of BPO and PMMA powders generated two peaks. One peak pattern was assigned to the decomposition of BPO included within the polymer particles. The results suggested that BPO was present inside the particles and little BPO was mixed into the resin powders. Moreover, the present study demonstrated a unique useability of DSC in characterizing resin powders.

Acrylic Resins↗
PubMed2000

What's new in imaging? New magnetic resonance imaging of esophageal cancer using an endoluminal surface coil and antibody-coated magnetite particles.

An endoluminal surface coil: Esophageal cancer was studied by high resolution magnetic resonance imaging (MRI) to determine the histopathologic basis for signal intensity in these lesions and to determine the potential of this modality for evaluating the depth of cancer invasion. In a basic study, 14 tumors were examined with a 1.5-T superconductive MR system using a surface coil. The esophageal wall could be differentiated into four layers on the T1-weighted images and seven layers on the T2-weighted images. The signal intensity of the tumor varied from low to intermediate on the T1- and T2-weighted images. The submucosal layer is important in evaluating cancer invasion on the T2-weighted images. In a clinical study, 30 patients with esophageal cancer were examined with a 1.5-T superconductive MR system using an endoluminal surface coil. In terms of depth of cancer invasion, the accuracy rate of MRI using the endoluminal surface coil was 83%. In conclusion, MRI with an endoluminal surface coil will be a useful examination for esophageal cancer in the future. Antibody-coated magnetite particles: A highly specific and effective MRI contrast agent was prepared by coating superparamagnetite particles with monoclonal antibodies (MAbs) directed against epidermal growth factor receptors (EGFRs), which are overexpressed in esophageal squamous cell carcinoma. The agent was shown to have EGFR-specific MRI contrast capacity in vivo in athymic rats bearing TE8 or H69 tumors. Immunospecific MRI using magnetite particles coated with MAbs against EGFR seems to be useful in the diagnosis of squamous cell carcinoma of the esophagus.

Animals↗
PubMed2000

[Pulmonary outflow tract reconstruction with autologous tissue during the Ross procedure: right ventricular characteristics in mid-term follow-up].

BACKGROUND: The Ross procedure requires the interposition of prosthetic or homograft extracardiac conduits to establish ventricle-pulmonary artery connection (RV-PA). These materials usually require multiple reoperations because of conduit failure. To avoid the re-replacement of currently available conduits, usage of autologous tissue may be preferable to reconstruct RV-PA connection during the Ross procedure, especially in the pediatric age group. METHOD: Ten patients (mean age 8.7 years, range 2-23) with congenital aortic valve disease underwent the Ross procedure between June, 1996 and July, 1998. To establish RV-PA continuity, autologous aortic wall including aortic valve with a gusset of pericardial tissue was used in six patients, rolled pericardial conduit with fresh pericardial bicuspid valve in three and one direct anastomosis of pulmonary posterior wall onto the right ventricle with a fresh pericardial monocusp valved patch. All patient's postoperative courses were uneventful. All patients were followed up (mean follow-up period: 21.6 +/- 6.6 months) and postoperative right ventricular characteristics, cardio-thoracic ratio (CTR) on chest X-ray and pulmonary valve function were evaluated. RESULTS: Postoperative right ventricular end-diastolic volume, right ventricular ejection fraction and right ventricular end-diastolic pressure did not change significantly (RVEDV: 128 to 113% of normal, RVEF: 56.4 to 51.5%, RVEDP: 5.9 to 10.1 mmHg). Pulmonary regurgitation during follow-up was mild in six patients and moderate in four. However, CTR decreased significantly over time (preop.: 56.5% postop.: 58.5%, late period: 53.4%). CONCLUSION: Our results support the concept of the reconstruction of pulmonary outflow tract without foreign materials during the Ross procedure. Longer follow-up are necessary to define the possible limitation of this technique.

Adult↗
PubMed2000

Accumulation of cAMP evoked by acetylcholine stimulation in rat submandibular acinar cells: observation of exocytosis, fluid secretion and [Ca2+]i.

The effects of cAMP accumulation evoked by acetylcholine (ACh) stimulation were studied in rat submandibular acinar cells by observing the exocytotic events, swelling of intercellular canaliculi (IC) and intracellular Ca2+ concentration ([Ca2+]i), which were monitored using an optical microscope. ACh stimulation evoked transient increases followed by sustained increases in the frequency of exocytotic events and IC swelling, while isoproterenol (isoprenaline; IPR) stimulation evoked sustained increases in these parameters. BAPTA treatment reduced the frequency of exocytotic events evoked by 5 microM ACh in the absence of extracellular Ca2+, and further addition of Rp-cAMPS or H-89 (protein kinase A (PKA) inhibitors) eliminated the remaining ACh-evoked responses (50 %). Addition of PKA inhibitors in the presence of extracellular Ca2+ reduced the frequency of exocytotic events evoked by 500 microM ACh in non-BAPTA-loaded cells. However, IC swelling evoked by 5 microM ACh was not affected by addition of PKA inhibitors, and was eliminated in BAPTA-loaded cells perfused with Ca2+-free solution. These results indicate that the IC swelling is regulated by [Ca2+]i and the frequency of exocytotic events is regulated by both [Ca2+]i and [cAMP]i during ACh stimulation. Addition of H-89 inhibited the capacitative Ca2+ entry into ACh-stimulated acinar cells. Biochemical analysis revealed that ACh stimulation increased the cAMP content in perfused submandibular glands. These results indicate that ACh stimulates the accumulation of cAMP in submandibular acinar cells and that this accumulation of cAMP modulates Ca2+-regulated exocytosis.

Acetylcholine↗
PubMed2000

Prognostic significance of self-measurements of blood pressure.

BACKGROUND: Self-measurements of blood pressure may offer some advantage in diagnostic and therapeutic evaluation and in management of patients. However, the most important limitation of self-measurement is that there are limited data available about the prognostic value of this information. RESULTS: Authors of several previous reports demonstrated that self-measurement reflects target-organ damage better than does casual measurement of blood pressure. So far, investigators in Tecumseh and Ohasama studies have provided pilot data on prognostic value of self-measurements. Investigators in Ohasama study demonstrated that self-measurements predict cardiovascular morbidity and mortality and all-cause mortality better than do casual measurements of blood pressure. Investigators in Tecumseh study demonstrated that self-measurement can predict future development of sustained hypertension and of diastolic dysfunction. These preliminary results suggest that self-measurements have strong predictive power for endpoints and surrogate measures of cardiovascular target-organ damage. CONCLUSION: The final answer on the prognostic significance of self-measurement has not been given. Prognostic studies designed to compare casual measurement of blood pressure, self-measurement, and ambulatory blood pressure monitoring are needed.

Blood Pressure Determination↗