Search PubMed⌕ Search

Biomedical subjects

A Maeda

Publications and source records attributed to A Maeda.

At least 271 records · Page 15Linked to original sources
PubMed1994

[A case report of type A acute aortic dissection, which arose from true aneurysm in aortic arch].

A 69-year-old woman was admitted to our hospital because of back pain. Examinations showed type A acute aortic dissection, which arose from true aneurysm in aortic arch, and emergency operation was considered. Deep hypothermic selective cerebral perfusion was carried out for brain protection. Ascending to aortic arch was replaced with 24 mm woven Dacron graft. There was no postoperative neurological complication.

Acute Disease↗
PubMed1994

[Study of 5'-DFUR treatment as postoperative adjuvant chemotherapy for stomach and colorectal cancer. Tokai GATS Group (pilot study)].

In order to study preliminary the safety of 5'-DFUR treatment as postoperative adjuvant therapy, intermittent and continuous treatment regimens were administered to patients undergoing curative resection of carcinomas of the stomach and the colorectum. Two treatment schedules were employed: 5'-DFUR was either given continuously in a daily oral dose of 600 mg/patient (continuous group) or for 2 weeks in a daily oral dose of 1,200 mg/patient followed by 2 weeks of no treatment (intermittent group). Twenty-one stomach cancer patients and 34 colorectal cancer patients were registered in the study. The rates of adverse drug reactions in the patients who completed treatment were 20.0% (2/10) in the continuous group and 50.0% (4/8) in the intermittent group of gastric cancer patients, and 16.6% (2/12) in the continuous group and 17.6% (3/17) in the intermittent group of colorectal cancer patients. The main adverse drug reactions were gastrointestinal symptoms. The incidence of diarrhea, a problematic side effect of 5'-DFUR, was 4.5% (1/22) in the continuous group and 12.0% (3/25) in the intermittent group. There were no statistically significant differences between the continuous group and the intermittent group in regard to the incidence of adverse drug reactions and survival rate. In addition, as there were no serious adverse drug reactions, both treatment regimens were demonstrated to be highly safe when administered as postoperative adjuvant therapy.

Administration, Oral↗
PubMed1993

Water structural changes in lumirhodopsin, metarhodopsin I, and metarhodopsin II upon photolysis of bovine rhodopsin: analysis by Fourier transform infrared spectroscopy.

Difference Fourier transform infrared spectra of lumirhodopsin, metarhodopsin I, and metarhodopsin II versus rhodopsin were recorded with hydrated films of bovine rod outer segments at 200, 240, and 270 K. In the region between 3700 and 3450 cm-1, the O-H stretching vibrational bands of water were identified by H(2)18O and 2H2O shifts. Lumirhodopsin and metarhodopsin I exhibit almost identical spectral shape in this region. The O-H stretching vibration band of water was detected at 3533 cm-1 upon formation of lumirhodopsin and metarhodopsin I and at 3641 cm-1 upon formation of metarhodopsin II. The results suggest that hydrogen bonding of water molecules in the protein is stronger in lumirhodopsin and metarhodopsin I, intermediates with a protonated Schiff base, than in metarhodopsin II with an unprotonated Schiff base. This is similar to the case of photoreaction of bacteriorhodopsin, in which stronger hydrogen bonding of water is formed in the L intermediate than the M intermediate [Maeda, A., Sasaki, J., Shichida, Y., & Yoshizawa, T. (1992) Biochemistry 31, 462-467].

Animals↗
PubMed1993

The post-translational processing of ras p21 is critical for its stimulation of mitogen-activated protein kinase.

The point-mutated active form of ras p21 is known to activate mitogen-activated protein (MAP) kinase/extracellular signal-regulated kinase (ERK) in intact mammalian cells and Xenopus oocytes, although the direct target molecule of ras p21 remains to be identified. To elucidate the role of the post-translational processing of ras p21 for the MAP kinase activation, we established the cell-free system in which ras p21 activated MAP kinase. The guanosine 5'-(3-O-thio)triphosphate (GTP gamma S) bound form of post-translationally processed Ki-ras 4B p21 activated MAP kinase in the cytosol fraction of Xenopus oocytes, but the GTP gamma S bound form of post-translationally unprocessed Ki-ras 4B p21 or the GDP bound form of processed or unprocessed Ki-ras 4B p21 was far less effective. The GTP gamma S bound form of processed Ki-ras 4B p21 activated recombinant ERK2 in the presence of the cytosol fraction of Xenopus oocytes, but the unprocessed protein was far less effective. These results provide a complete biochemical assay for ras p21 to activate MAP kinase in a cell-free system and indicate that all the elements downstream of ras p21 necessary for the MAP kinase activation are cytosolic and that the post-translational processing of ras p21 is important for the MAP kinase activation.

Animals↗
PubMed1993

A protein factor for ras p21-dependent activation of mitogen-activated protein (MAP) kinase through MAP kinase kinase.

To identify the direct target molecule of ras p21 in higher eukaryotes, we have recently developed the cell-free system in which ras p21 activates mitogen-activated protein (MAP) kinase/extracellular signal-regulated kinase (ERK). In this cell-free system, the guanosine 5'-[gamma-thio]triphosphate- bound form of Ki-ras p21, but not the GDP-bound form, activates endogenous Xenopus MAP kinase as well as recombinant ERK2 in the presence of the cytosol fraction of Xenopus oocytes. We separated two protein factors from the cytosol fraction of Xenopus oocytes by column chromatography: one was the inactive form of MAP kinase kinase and the other was a factor tentatively named ras p21-dependent ERK-kinase stimulator (REKS). The former and latter showed M(r) values of approximately 45,000 and 150,000-200,000, respectively, as estimated by gel filtration. Both factors were necessary for Ki-ras p21-dependent activation of MAP kinase/ERK2. These results indicate that an additional protein factor (REKS) is essential for Ki-ras p21 to activate MAP kinase through MAP kinase kinase.

Animals↗
PubMed1993

Time-resolved infrared spectral analysis of the KL-to-L conversion in the photocycle of bacteriorhodopsin.

Time-resolved infrared spectra of the hydrated film of light-adapted bacteriorhodopsin were recorded from earlier than 200 ns to 450 microseconds after light excitation in the 1800-900-cm-1 region on a newly designed dispersive-type infrared spectrometer [Iwata & Hamaguchi (1989) Appl. Spectrosc. 44, 1431-1437]. Both the KL-to-L and L-to-M conversions were detected in this time range. The spectral shape of KL is similar to K measured at 77 K except for the intense hydrogen out-of-plane vibrational band at 984 cm-1. The kinetics of this band are different from those of the other KL-specific bands at 1510, 1296, and 956 cm-1. Since the hydrogen out-of-plane vibrational bands are intensified by twists of the polyene chain, a change in the twist of the chromophore is suggested within the lifetime of KL. During the decaying process of L, the KL-specific vibrational bands are observed in parallel with L, indicating that KL and L are in equilibrium.

Bacteriorhodopsins↗
PubMed1993

Effects of solvent preservation with or without gamma irradiation on the material properties of canine tendon allografts.

We studied the effects of solvent preservation with and without gamma irradiation on the material properties and morphology of canine tendons. Twenty-four paired tendons were harvested from both hind limbs of eight dogs. The tendons from the right legs were divided into three treatment groups of eight tendons each. In the first group, the tendons were subjected to solvent preservation for sterilization and drying (solvent group). In the second group, the tendons were treated in the same manner and then were sterilized by gamma irradiation (solvent/gamma group). The same treatments were applied to the tendons in the third group but in reverse order (gamma/solvent group). Tendons from the contralateral left legs were frozen immediately for use as controls for each corresponding treatment group. Histologically, the tendons treated with solvent, with or without gamma irradiation, had a more prominent wavy pattern in the collagen fibers than the control tendons. Mechanically, the tangent moduli for the solvent, solvent/gamma, and gamma/solvent groups were 58, 53, and 99%, respectively, of each contralateral control. The respective tensile strengths were 85, 39, and 86% of that of the contralateral control. The tendons in the solvent/gamma group underwent the most severe changes in material properties; the tendons in the gamma/solvent group changed the least. This suggests that gamma irradiation followed by solvent drying is the procedure of choice for the preservation of tendon allografts.

Animals↗
PubMed1993

Inhibition of mouse hepatitis virus multiplication by antisense oligonucleotide, antisense RNA, sense RNA and ribozyme.

Antisense nucleic acids against specific sequences of mouse hepatitis virus (MHV)-RNAs were tested for their inhibitory effects on viral multiplication in mouse DBT cells. An antisense oligonucleotide containing a sequence complementary to leader RNA was synthesized and shown to induce a significant inhibitory effect on the multiplication of MHV-JHM. A vector which expressed the antisense or sense mRNA7 of MHV was transfected into DBT cells. A decreased multiplication of MHV was observed in both cell lines. The transfected cell line which expressed ribozyme against the 5'-end of the MHV genome was established. The rate of inhibition of MHV-multiplication and the quantity of synthesized virus-specific mRNAs in this transfected cell line were the same for both antisense and sense RNA. These results show that antisense nucleic acids might be eligible for use as antiviral agents against MHV multiplication.

Animals↗
PubMed1993

Differentiation of Dunn osteosarcoma cells in response to dibutyryl cyclic 3',5'-adenosine monophosphate.

We investigated the effects of dibutyryl cyclic adenosine 3',5'-monophosphate (Bt2cAMP) on the differentiation of Dunn osteosarcoma cells. Flow-cytometric analysis and DNA synthesis assay showed that Bt2cAMP decreased the cell population in the S phase in a time- and dose-dependent manner. Also, the cells showed distinct morphological and functional alterations; the cell morphology changed to a fibroblast-like appearance with long and thin protoplasmic processes, the knobs or blebs on both the cell membrane and nuclear membrane disappeared and the intracellular alkaline phosphatase activity increased. Moreover, Bt2cAMP-treated cells secreted a large quantity of fibronectin, which was deposited on the extended cell surface in the culture medium. Thus, Dunn osteosarcoma cells are differentiated morphologically and functionally by Bt2cAMP, and might be transformed to benign precursor cells.

Alkaline Phosphatase↗
PubMed1993

The evidence of human herpesvirus 6 infection in the lymph nodes of Hodgkin's disease.

Human herpesvirus 6 (HHV-6), the causative agent of exanthem subitum, has been implicated in other diseases. Recently HHV-6-specific sequences have been detected by Southern blot analysis and polymerase chain reaction in the lymph nodes of three patients with Hodgkin's disease. The pathological localization of HHV-6, however, is still unknown. In order to study the pathological role of HHV-6 in Hodgkin's disease, we investigated, by immunohistochemical and molecular methods, two lymph node biopsies taken from a 7-year-old boy with Hodgkin's disease during the course of disease evolution. Although the histopathological findings of the first biopsy differed from those of the second, HHV-6 antigens and sequences could be detected in both lymph nodes by immunohistochemistry and in situ hybridization, respectively. HHV-6 was localized in macrophages, predominantly in lymphoid follicles, but not in Reed-Sternberg cells. Antibody titres to HHV-6 were consistent with reactivation of latency. Neither cytomegalovirus nor Epstein-Barr virus was present. Our data suggest a role for HHV-6 in the pathogenesis of Hodgkin's disease.

Antibodies, Viral↗
PubMed1993

Human urinary excretion of L-histidine-related compounds after ingestion of several meats and fish muscle.

1. After oral administration of the muscle of skipjack tuna, about 90% of ingested anserine (Ans) was excreted quickly into urine as Ans (8%) and pi-methylHis (82%), indicating the fast decomposition of Ans into pi-methylHis. This was also the case for chicken muscle ingestion. 2. After eel muscle ingestion, carnosine (Car) excretion was only 1% of the ingested whereas almost no increase was found in His, a constituent of Car, indicating the re-utilization of this essential amino acid. Similar results were also obtained from beef and pork ingestion. 3. In all cases, the urinary excretion of these compounds reached a maximum within 7 hr after ingestion and returned to the level of meat-free diet within 40 hr.

Adolescent↗
PubMed1993

Inactivation of rifampin by Nocardia brasiliensis.

Rifampin was glycosylated by a pathogenic species of Nocardia, i.e., Nocardia brasiliensis. The structures of two glycosylated compounds (RIP-1 and RIP-2) isolated from the culture broth of the bacterium were determined to be 3-formyl-23-(O-[beta-D-glucopyranosyl])rifamycin SV and 23-(O-[beta-D-glucopyranosyl])rifampin, respectively. Both compounds lacked antimicrobial activity against other gram-positive bacteria as well as the Nocardia species.

Glycosylation↗
PubMed1993

Computer-assisted three-dimensional image analysis of cerebral amyloid angiopathy.

BACKGROUND AND PURPOSE: Microaneurysms and fibrinoid necrosis of cerebral cortical arteries have been reported to be related to the pathogenesis of intracerebral hemorrhage associated with cerebral amyloid angiopathy. To elucidate the pathogenesis of such vascular lesions, we conducted the present study. METHODS: Five hundred serial sections from brain tissue of a patient with severe amyloid angiopathy and intracerebral hemorrhage were analyzed histologically and immunohistochemically. Three-dimensional reconstructions of the vascular lesions were performed using a computer-assisted image analysis system. RESULTS: The microaneurysms were found to develop in small cortical arteries with diameters of about 40 to 50 microns. They were spindle-shaped dilatations, with a maximum diameter of about 200 microns, and appeared within vascular segments bearing severe amyloid deposition. In the walls of the aneurysms, the intima was thickened, and the media and adventitia showed thinning and disruption. Fibrinoid necrosis was found in the vascular walls of the most dilated, middle portions of the aneurysm. The vascular walls undergoing fibrinoid necrosis did not show any beta/A4 or cystatin C but presented with fibrinogen-like immunoreactivities, indicating invasion of plasma components. CONCLUSIONS: These results suggested the following sequential events for the pathogenesis of the cerebral amyloid angiopathy-associated vascular lesions leading to hemorrhage: (1) damage of the media and adventitia due to severe amyloid deposition results in dilatation of the cortical arteries, (2) the vascular dilatation progresses and is accompanied by thickening of the intima and disruption of the media and adventitia (microaneurysm formation), (3) plasma components invade to the vascular wall (fibrinoid necrosis), and (4) finally, hemorrhage develops.

Aged↗
PubMed1993

[The effect of the motion of forefoot joint at the force exerted upon the floor during walking exercise].

In walking exercise the human body is exposed to external forces. Some of them are produced by constraints such as surface, shoes or opponent. In kick action of walking, the ground reaction force (GRF) is the most important external force. The magnitude of the GRF, its direction, and point of application have an influence on the load on the human body. The purpose of this study is to clarify the role of forefoot joint (artt. metatarsophalangeae) at the force exerted upon the floor during kick action of walking. The device used in this study to analyze the GRF and its three components consists of Kistler's force platform. Output from force transducer was collected online with a TEAC data recorder and MEM-4101 minicomputer. The impact force measurements were taken from the anterior-posterior force time curves at the take-off for 1 subject walking 10 trials at 2 m/sec with 2 different pairs of shoes (Shoes 1: thin sole of 4mm, and Shoes 2: thick sole of 40mm) and without shoes. High speed (200f/sec) cinematography was also used to analyze the angular displacement of forefoot joint at the take-off of walking exercise. The force acting at the forefoot joint may produce the anterior-posterior force of the GRF which is defined as the propelling power acting on the human body during walking exercise. The result showed that the impact force peak occurred 40-60 msec before take-off and the propelling part of kick action accounted for only about 6% of the external force.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise↗
PubMed1993

Inactivated products of rifampicin by pathogenic Nocardia spp.: structures of glycosylated and phosphorylated metabolites of rifampicin and 3-formylrifamycin SV.

Rifampicin (1) was converted into four inactivated products by pathogenic Nocardia, RIP-1 and RIP-2 by N. brasiliensis and RIP-3 and RIP-4 by N. otitidiscaviarum. MS and NMR analysis showed the compounds to be 3-formyl-23-[O-(beta-D-glucopyranosyl)]rifamycin SV (2), 23-[O-(beta-D-glucopyranosyl)]rifampicin (3), 21-(O-phosphoryl)rifampicin (4) and 3-formyl-21-(O-phosphoryl)-rifamycin SV (5), respectively.

Drug Resistance↗
PubMed1993

[Coronary artery bypass grafting in six patients with familial hypercholesterolemia].

UNLABELLED: From June 1989 through November 1991, six patients with familial hypercholesterolemia underwent surgical treatments. The surgical procedures were coronary artery bypass grafting (CABG) alone 4, ligation of coronary aneurysm + CABG 1, and CABG + femoro-femoral bypass 1. There were no operative or hospital deaths. Early post operative patency rate of the grafts was 100%. CASE PRESENTATION: A 44-year-old man whose anginal pain recurred 11 years after CABG. Coronary angiogram revealed stenosis and a large aneurysm in the circumflex coronary artery. Previous grafts to the left anterior descending coronary artery and diagonal branch were patent. Ligation of the aneurysm and internal mammary artery bypass grafting were performed. Postoperatively, the patient has remained asymptomatic. Our data indicate that CABG for FH patients is effective in the early postoperative period.

Adult↗
PubMed1993

[A case report of congenitally bicuspid aortic valve and ascending aortic aneurysm treated by wheat operation].

A 59-year-old man who complained of palpitation was diagnosed as having a congenitally bicuspid aortic valve, severe aortic regurgitation, and an ascending aortic aneurysm. He underwent aortic valve replacement and conduit replacement by the modified Wheat technique. Since this technique requires no coronary artery anastomosis, it causes no problems associated with reconstruction of the coronary artery. Postoperative angiogram revealed no aneurysm formation of the aortic root or paravalvular leakage. This case suggest that aneurysm of the ascending aorta with aortic regurgitation is more effectively treated by the modified Wheat technique if cephalad displacement of the coronary ostium is not extensive.

Aorta↗