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Biomedical subjects

H Itoh

Publications and source records attributed to H Itoh.

At least 883 records · Page 49Linked to original sources
PubMed1993

Orientation of actin monomers in moving actin filaments.

We have visualized, under an optical microscope, the orientations of actin monomers in individual actin filaments undergoing Brownian motion in solution, actively sliding past myosin molecules, or immobile on a surface. For the visualization, two strategies have been adopted. One is to exploit the fluorescence polarization of a fluorescent probe firmly attached to actin. Using the probe phalloidin-tetramethylrhodamine, the fluorescence was clearly polarized along the filament axis, showing alignment of the probe molecules along the filament axis. Within our temporal resolution of 33 ms and spatial resolution of better than 1 micron (average over approximately 10(2) actin monomers), the orientation of the probe (hence of actin monomers) did not change upon interaction of the filament with heavy meromyosin; myosin-induced reorientation was estimated to be a few degrees at most. This first method, while highly sensitive to small reorientations of monomers off or toward the filament axis, does not report on reorientations around the axis. To detect rotation around the filament axis, we adopted the second strategy in which we attached small plastic beads to the actin filaments. Axial turns would be immediately apparent from the movement of the beads. Preliminary observations indicate that actin filaments can slide over a heavy meromyosin-coated surface without axial rotations. Since rotations have been implicated in different experiments, we are currently investigating the source of the apparent discrepancy. The attached bead also serves as a handle through which we can apply force, via optical tweezers, on the filament. By letting the sliding actin filament pull the bead against the optical force, we were able to estimate the sliding force and its fluctuation.

Actin Cytoskeleton↗
PubMed1993

Turcot's syndrome and familial adenomatous polyposis associated with brain tumor: review of related literature.

We investigated clinical manifestations in 124 patients with a possible Turcot's syndrome whose data were taken from documented cases. The cases were subclassified mainly on the bases of the type of familial occurrence and listed in five Tables. We searched for differences in colonic manifestation, histologic type of glioma, mode of inheritance, frequency of parental consanguinity, skin lesions and other accompanying lesions among these five groups. The differences of these clinical findings suggested that glioma-polyposis syndrome should be classified as follows; (1) cases of Turcot's syndrome who had characteristic colonic and brain manifestations, (2) cases of FAP associated with glioma, (3) suspicious cases of glioma-polyposis, and (4) cases other than glioma-polyposis syndrome.

Adenomatous Polyposis Coli↗
PubMed1993

Myelodysplastic syndrome associated with relapsing polychondritis: unusual transformation from refractory anemia to chronic myelomonocytic leukemia.

The authors report an unusual case of myelodysplastic syndrome (MDS) associated with relapsing polychondritis (RP), which developed at almost the same time as MDS. The initial diagnosis was MDS, refractory anemia (RA) subtype, according to the FAB classification. Symptoms of RP were apparently controlled by oral administration of prednisolone (PSL), although MDS was not. Within 1 month after the diagnosis, monocytosis and thrombocytopenia without excess of blasts became prominent and transformation from RA to chronic myelomonocytic leukemia (CMML) was recognized. Combination chemotherapy including daunorubicin (DNR) and cytosine arabinoside (ara-c) did not subdue the progressive monocytosis and thrombocytopenia. Finally, the patient died of pulmonary hemorrhage 3 months after the onset of the disease. The prognosis of MDS may be poorly influenced by association with RP.

Anemia, Refractory↗
PubMed1993

Portal vein infusion of cancer chemotherapeutic agent emulsified with Lipiodol in regenerating liver after partial hepatectomy in rats.

Portal vein infusion of aclarubicin (ACR) emulsified with Lipiodol (LP) in regenerating liver after 70% partial hepatectomy in rats was evaluated for its safety and usefulness. DNA synthesis in regenerating liver was transiently suppressed by LP, ACR or LP+ACR, but no obvious inhibition was seen in aminopyrine N-demethylase activity and liver weights. LP significantly enhanced hepatic tissue levels of ACR and its active metabolites by long-term retention in the sinusoidal space. This study demonstrates that in rats LP has a powerful effect on the long-term retention of anticancer agents in the sinusoidal space after infusion into the portal vein, without aggravating hepatic damage by anticancer agents.

Aclarubicin↗
PubMed1993

A case of serous cystadenoma of the pancreas with focal malignant changes.

We present a serous cystadenoma of the pancreas with focal malignant changes, and describe its characteristic histological features. On gross examination, a tumor was present on the anterior surface of the body of the pancreas and measured approx 25 x 25 x 20 mm. Microscopically, most tumor cells showed the typical histological features of serous cystadenoma, characterized by a microcystic architecture and glycogen-rich cells with a uniform and bland appearance. However, in some areas, a tendency to papillary structures with fibrovascular cores was noted. These papillary lesions were composed mainly of nonmucinous, glycogen-poor epithelial cells, the nuclei of which showed a mild atypia. In addition, vascular and perivascular invasion was focally observed. However, there was no clinical evidence of local or distant metastasis. From these findings, we diagnosed this lesion as a serous cystadenoma of the pancreas with focal malignant changes rather than a serous cystadenocarcinoma of the pancreas.

Blood Vessels↗
PubMed1993

Domain structure of the 90-kDa stress protein: heparin- and antibody-binding domain.

1. To understand the physiological roles of the 90-kDa stress protein (HSP90), we investigated the heparin- and antibody-binding domains of the protein. 2. For heparin-binding sites, HSP90 was digested completely with trypsin, and the digests were applied to a heparin-Sepharose column and eluted with 1.0 M NaCl, followed by 8.0 M urea. 3. Each elutant was purified by a reverse-phase C18 column. 4. Two peptides from the NaCl-eluted fraction and no peptide from the urea-eluted fraction were purified. 5. The purified peptides were sequenced by an automated peptide sequencer. 6. One of the heparin-binding sites was present between Leu-362 and Arg-365; another was present between Leu-645 and Lys-648. 7. These two peptides were basic and considerably hydrophilic. 8. For antibody-binding sites, HSP90 was mildly digested with trypsin, electrophoresed on SDS-polyacrylamide gels and transferred to PVDF membranes. 9. The four bound of the trypsin fragments could be sequenced with a peptide sequencer. 10. There was only one antibody-binding peptide, 38 kDa, starting from Pro-2. The others showed no cross-reactivity with the antibody and started from Leu-283. 11. Therefore, the epitopes of HSP90 are present between Pro-2 and Leu-282. 12. The heparin-binding sites are present from the middle region of the HSP90 molecule, and the antigen sites are at the N-terminal domain.

Amino Acid Sequence↗
PubMed1993

Physicochemical property of bovine brain 73-kDa stress protein.

1. An approximately 70-kDa protein was purified from bovine brain using an ATP-Sepharose column. 2. The protein sample was found to contain two proteins (major 73 kDa and minor 72 kDa) on two-dimensional gel electrophoresis. 3. Antibodies raised against the 73- and 72-kDa proteins cross-reacted with stress-induced HSP73 and HSP72 from HeLa cells, respectively. 4. Heparin-binding peptides were obtained from trypsin digests of HSP73.

Amino Acid Sequence↗
PubMed1993

Localization of HSP90 in rat brain.

1. In rats, HSP90 (90-kDa heat shock protein) was abundant in the brain compared with the liver and kidney. Immunohistochemical studies showed the presence of HSP90 in almost all neurons in the brain. 2. On immunoblotting using an anti-HSP90 antibody, HSP90 was present in a lower amount in the medulla oblongata and spinal cord. 3. In the pituitary gland, some of superficial cells of the anterior lobe adjacent to the middle lobe was specifically stained with anti-HSP90 antibody.

Animals↗
PubMed1993

Age-related reduction of reflex bradycardia in conscious rats by catecholaminergic nucleus tractus solitarius lesions.

To determine whether catecholaminergic lesions in the nucleus tractus solitarius (NTS) have age-related baroreflex effects, we compared conscious 3-month- and 14-month-old rats pretreated with either 6-hydroxydopamine (6-OHDA) or vehicle injected into the NTS. Body weights fell immediately in both age groups, but after 2 weeks the weight loss persisted only in 14-month-old rats. Mean pressures and heart rates, though diminished after 3 days, were later elevated slightly in 3-month- but not in 14-month-old rats. Two weeks after 6-OHDA pretreatment, reflex tachycardia was reduced in both age groups, but reflex bradycardia was reduced only in 3-month-old and not in 14-month-old rats. Corresponding changes in vehicle-treated rats were not significant. Because 6-OHDA induced lesions in the NTS inhibited reflex bradycardia selectively at 3 but not at 14 months of age, our results suggest that catecholaminergic mechanisms in the NTS for regulating reflex bradycardia become impaired with age.

Aging↗
PubMed1993

Management of concomitant abdominal aortic aneurysm and gastrointestinal malignancy.

Selecting the most appropriate surgical approach for patients with abdominal aortic aneurysm (AAA) and gastrointestinal malignancy remains controversial. In an attempt to develop guidelines for the management of patients with these two simultaneous lesions, a retrospective review of patients who had concomitant AAA and gastrointestinal malignancy was undertaken. During the period from January 1985 to February 1993, 229 patients with AAA were admitted to our hospital. Among these, 19 patients (8%) had a gastrointestinal malignancy together with AAA and were divided into 2 groups. Group I was composed of 11 patients who underwent either a 1- or a 2-stage operation for both lesions. Group II was composed of eight patients who either underwent an operation for one lesion (six patients) or did not have any operation (two patients). Among group I, six patients underwent the two-stage operation. In four of the six patients, the malignancy was resected first. In the remaining two patients, the aneurysmectomy was performed first, because, in one patient, the aneurysm was more than 6 cm in diameter, and, in the other patient, the aneurysm was a saccular type. Among group I, five patients (two patients with gastric cancer, and one patient each with esophageal cancer, rectal cancer, and malignant lymphoma of the stomach) underwent a one-stage operation. In three of the five patients (two patients with gastric cancer and one patient with esophageal cancer), simultaneous resection was carried out by using segregated approaches, namely, the retroperitoneal approach for AAA and the transperitoneal approach for malignancy. Although the clinical characteristics of the patients were different, 8 of the 11 patients (73%) in group I are still alive, whereas only 1 of the 8 patients (13%) in group II is still alive. The principles of our surgical approaches for concomitant AAA and gastrointestinal malignancy are as follows: (1) The lesion that absolutely indicated urgent surgery was resected first. (2) If both lesions were asymptomatic, the malignancy was resected first. (3) Simultaneous resection using different approaches was useful in some patients with concomitant upper early gastrointestinal malignancy. (4) Both lesions need to be resected eventually for better long-term survival.

Aortic Aneurysm, Abdominal↗
PubMed1993

Time courses of cell electroporation as revealed by submicrosecond imaging of transmembrane potential.

Changes in the membrane conductance of sea urchin eggs, during the course of electroporation, were investigated over the time range of 0.5 microsecond to 1 ms by imaging the transmembrane potential at a submicrosecond resolution with the voltage-sensitive fluorescent dye RH292. When a rectangular electric pulse of moderate intensity was applied across an egg, a position-dependent potential developed synchronously with the pulse, as theory predicts for a cell with an insulating membrane. From the rise and fall times, the membrane capacitance of unfertilized eggs was estimated to be 0.95 microF/cm2 and the intracellular conductance 220 omega.cm. Under an electric pulse of much higher intensity, the rise of the induced potential stopped at a certain level and then slowly decreased on the microsecond time scale. This saturation and subsequent reversal of the potential development was ascribed to the introduction of finite membrane conductance, or permeabilization of the membrane, by the action of the intense pulse (electroporation). Detailed analysis indicated the following: already at 0.5 microsecond in the rectangular electric pulse, the two sides of the egg facing the positive and negative electrodes were porated and gave a high membrane conductance in the order of 1 S/cm2; the conductance on the positive side appeared higher. Thereafter, the conductance increased steadily, reaching the order of 10 S/cm2 by 1 ms. This increase was faster on the negative-electrode side; by 1 ms the conductance on the negative side was more than twice that on the positive side. The recovery of the porated membrane after the pulse treatment was assessed from the membrane conductance estimated in a second electric pulse of a small amplitude. At least two recovery processes were distinguished, one with a time constant of 7 microseconds and the other 0.5 ms, at the end of which the membrane conductance was already < 0.1 S/cm2.

Animals↗
PubMed1993

Correlation of long-term results of extra-anatomic bypass and flow waveform analysis.

To investigate the correlation between the long-term results of an extra-anatomic bypass and operative flow waveform analysis, we retrospectively reviewed 32 axillofemoral and 21 femorofemoral bypasses for between 1 and 5 years after surgical repair. For the grafts with a type O or I flow waveform pattern, the patency at 3 years (83%) and at 5 years (83%) was superior to grafts with a type II flow waveform (69 and 60%). For the axillofemoral bypass grafts with a type O or I waveform, the patency rate was 92% at 5 years. In contrast with the type II flow, the patency rate was 70% at 5 years. For the femorofemoral bypass with a type O or I and a II flow waveform, the patency at 4 years was 67 and 46%, respectively. In cases with concomitant superficial femoral artery occlusion, the flow waveform was type O or I in 23% and type II in 77%. The patency rate at 5 years was 85% for cases with a patent superficial femoral artery, and 51% for an occluded superficial femoral artery (p < 0.05). These results suggest that the long-term outcome of extra-anatomic bypass correlates with the operative flow wave analysis. In addition, good long-term results and an accurate flow wave pattern depend on the distal run-off, particularly the presence of a patent superficial femoral artery.

Adult↗
PubMed1993

Role of NO on pressure-natriuresis in Wistar-Kyoto and spontaneously hypertensive rats.

We investigated the role of the endothelium-derived relaxing factor nitric oxide (NO) on pressure-natriuresis in spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) using in vivo perfusion studies. Differences in the neural and hormonal background to the kidney were minimized by renal denervation and by holding plasma vasopressin, aldosterone, corticosterone, and norepinephrine levels constant by intravenous infusion. In WKY, elevation of renal perfusion pressure (RPP) from 115 to 157 mm Hg increased urinary sodium excretion 4.5 to 14.8 microEq/min/g kidney wt, and the slope of its linear regression was 0.21 microEq/min/g kidney wt/mm Hg. Infusion of an inhibitor of NO synthase, L-NMMA (1 mg/min/kg), lowered this slope (P < 0.05) but L-arginine (3 mg/min/kg) did not change it. By contrast, the impaired pressure-natriuresis response of SHR was ameliorated by L-arginine (slope: 0.08 to 0.16; P < 0.05), while L-NMMA did not blunt it further. GFR and renal plasma flow (RPF) were well autoregulated in both strains, but L-NMMA lowered RPF significantly (SHR: from 4.2 to 2.6 ml/min/g kidney wt; WKY: 4.5 to 2.5 ml/min/g kidney wt). Moreover, when infused simultaneously, all these individual effects of L-NMMA and L-arginine were nullified. These results suggest that NO plays an important role in the pressure-natriuresis mechanism.

Amino Acid Oxidoreductases↗
PubMed1993

Enzymuria in non-insulin-dependent diabetic patients: signs of tubular cell dysfunction.

1. To evaluate tubular damage in diabetic patients, we measured the 24 h urinary excretion of five enzymes (N-acetyl-beta-D-glucosaminidase, gamma-glutamyl transpeptidase, dipeptidyl aminopeptidase IV, alanine aminopeptidase and alkaline phosphatase) that originate in renal proximal tubular cells. 2. Studies were performed on 118 non-insulin-dependent diabetic patients, 59 non-diabetic patients with chronic renal disease and 47 normal control subjects. First, the correlation between renal function, glycaemic control and urinary enzyme excretion was investigated. Secondly, the subjects were treated by controlled diet therapy to assess the effects of better glycaemic control on urinary enzyme excretion. 3. Regardless of a diabetic or non-diabetic cause of renal dysfunction, all of the five enzymes showed abnormal urinary excretion in patients with renal insufficiency (serum creatinine concentration > 2.0 mg/dl). In diabetic patients, however, an increase in N-acetyl-beta-D-glucosaminidase excretion and a decrease in gamma-glutamyl transpeptidase excretion were noted even in those who had no signs of renal dysfunction, including microalbuminuria. Moreover, the excretion of these two enzymes had a higher degree of correlation with glycaemic control and renal function than did that of the other three enzymes. Multiple regression analysis revealed that excretion of N-acetyl-beta-D-glucosaminidase is best correlated with urinary protein (r2 = 0.35), whereas excretion of gamma-glutamyl transpeptidase is closely associated with glomerular filtration rate (r2 = 0.33). 4. In diabetic patients, diet therapy improved glycaemic control but had no effects on renal function, microalbumin excretion and beta 2-microglobulin excretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylglucosaminidase↗
PubMed1993

Involvement of endogenous cholecystokinin in the development of acute pancreatitis induced by closed duodenal loop.

Involvement of endogenous cholecystokinin (CCK) in the development of acute pancreatitis induced in rats by closed duodenal loop (CDL) was examined, and the effects of the potent and specific CCK receptor antagonist loxiglumide on this model of acute pancreatitis were evaluated. Plasma CCK bioactivity was markedly elevated 3 and 6 h after onset of acute pancreatitis. A single subcutaneous injection of 50 mg/kg body wt of loxiglumide 30 min before the induction of acute pancreatitis completely eliminated the hypercholecystokinemia. Loxiglumide given 3 h after the induction of acute pancreatitis suppressed plasma CCK bioactivity, which had risen up to 30-fold over basal value (0 h) at 3 h, to nearly the basal level. Loxiglumide pretreatment, in addition, significantly prevented the rise in serum amylase and lipase activity, as well as the increase in ascitic volume. It also ameliorated histological alterations of hemorrhagic and necrotizing pancreatitis. Reduction of plasma CCK bioactivity by loxiglumide after the onset of pancreatitis slowed the rate of progression of pancreatitis. However, pancreatic wet weight and cellular infiltration were not significantly influenced by loxiglumide treatment. These observations suggest that endogenous CCK is not involved in the initiation of acute hemorrhagic and necrotizing pancreatitis induced by CDL, but is involved in the development of pancreatitis in this model.

Acute Disease↗
PubMed1993

The natriuretic peptide family.

The natriuretic peptide system is a complicated system comprising at least three endogenous peptides, atrial natriuretic peptide, brain natriuretic peptide, and C-type natriuretic peptide and three receptors, the atrial natriuretic peptide-A receptor (guanylyl cyclase A), the atrial natriuretic peptide-B receptor (guanylyl cyclase B), and the clearance receptor. The accumulated evidence indicates that this system is implicated in the control of blood pressure, body fluid homeostasis, and vascular remodeling as both cardiac hormone and local regulator.

Animals↗
PubMed1993

Isolation and characterization of two distinct gonadotropins, GTHI and GTHII, from bonito (Katsuwonus plelamis) pituitary glands.

Two distinct glycoproteins homologous to chum salmon GTHI and GTHII were isolated from the pituitary glands of a marine fish, the bonito (Katsuwonus plelamis), and characterized by amino acid sequence analysis in order to obtain additional evidence for duality of teleost GTHs. Glycoproteins were extracted from the pituitary glands, and intact GTHI and GTHII, consisting of two distinct subunits, were purified by ion-exchange chromatography on DEAE-cellulose, rpHPLC on Asahipak C4P-50 in alkaline buffer, and gel filtration on Superdex 75. The association of the subunits was stable in GTHI (39 kD) and unstable in GTHII (30 kD) in acidic conditions. Immunoblotting revealed that antisera against beta subunits of chum salmon GTHs reacted with GTHII, but not with GTHI. In addition, none of the GTHs was stained with antiserum against human TSH beta. Sequence analysis demonstrated that bonito GTHI beta is homologous to salmon GTHI beta with 43% sequence identity, and bonito GTHII beta is homologous to salmon GTHII beta with 67% identity. Sequence identity between bonito GTHI beta and GTHII beta was only 28%. Thus, it is evident that the bonito pituitary gland produces two chemically distinct gonadotropins homologous to chum salmon GTHs.

Amino Acid Sequence↗