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Biomedical subjects

H Iwata

Publications and source records attributed to H Iwata.

At least 19 recordsLinked to original sources
PubMed1992

Localization of basic fibroblast growth factor-like immunoreactivity in the rat brain.

The immunohistochemical localization of basic fibroblast growth factor (bFGF) was studied in the adult rat brain, using a specific antibody against a synthetic bFGF fragment (the N-terminal 12 residues). Widespread but uneven regional localization of bFGF-like immunoreactive neurons and fibers was observed. Ependymal cells were also stained. The immunoreactive neurons were found in the cerebral cortex, olfactory bulb, septum, basal magnocellular nuclei, thalamus, hypothalamus, globus pallidus, hippocampus, amygdala, red nucleus, central gray of the midbrain, cerebellum, dorsal tegmental area, reticular formation, cranial motor nuclei and spinal cord. Immunoreactive fiber bundles and nerve terminals were also detected. These results indicate that bFGF is produced by or present in a specific neuronal cell population of the central nervous system.

Amino Acid Sequence↗
PubMed1992

Cell-cell interaction in graft rejection responses: induction of anti-allo-class I H-2 tolerance is prevented by immune responses against allo-class II H-2 antigens coexpressed on tolerogen.

The intravenous sensitization of C57BL/6 (B6) mice with class I H-2-disparate B6-C-H-2bm1 (bm1) spleen cells results in almost complete abrogation of anti-bm1 CD8+ helper (proliferative and interleukin 2-producing) T cell (Th) activities. Although an appreciable portion of CD8+ cytotoxic T lymphocyte (CTL) precursors themselves remained after this regimen, such a residual CTL activity was eliminated after the engrafting of bm1 grafts, and these grafts exhibited prolonged survival. In contrast, the intravenous sensitization with (bm1 x B6-C-H-2bm12 [bm12])F1 cells instead of bm1 cells failed to induce the prolongation of bm1 graft survival as well as bm12 and (bm1 x bm12)F1 graft survival. In the (bm1 x bm12)F1-presensitized B6 mice before as well as after the engrafting of bm1 grafts, anti-bm1 CTL responses that were comparable to or slightly stronger than those observed in unpresensitized mice were induced in the absence of anti-bm1 Th activities. bm1 graft survival was also prolonged by intravenous presensitization with a mixture of bm1 and bm12 cells but not with a mixture of bm1 and (bm1 x bm12)F1 cells. The capacity of CD4+ T cells to reject bm12 grafts was eliminated by intravenous presensitization with antigen-presenting cell (APC)-depleted bm12 spleen cells. However, intravenous presensitization with APC-depleted (bm1 x bm12)F1 cells failed to induce the prolongation of bm1 graft survival under conditions in which appreciably prolonged bm12 graft survival was induced. More surprisingly, bm1 graft survival was not prolonged even when the (bm1 x bm12)F1 cell presensitization was performed in CD4+ T cell-depleted B6 mice. This contrasted with the fact that conventional class I-disparate grafts capable of activating self Ia-restricted CD4+ as well as allo-class I-reactive CD8+ Th exhibited prolonged survival in CD4+ T cell-depleted, class I-disparate cell-presensitized mice. These results indicate that: (a) intravenous presensitization with class I- and II-disparate cells fails to reduce anti-allo-class I rejection responses that would otherwise be eliminated using only class I-disparate cells; (b) such failure is generated according to the coexpression of both classes of alloantigens on a single cell as tolerogen; and (c) allo-class II antigens coexpressed on tolerogen function to activate CD4+ as well as non-CD4+ Th leading to the generation of anti-class I effector T cell responses.

Animals↗
PubMed1992

Agarose for a bioartificial pancreas.

Islets were encapsulated into 5% concentration agarose microbeads. The effect of microencapsulation on islet allograft survivals was determined using a streptozotocin-induced diabetic (STZ) mouse and a nonobese diabetic (NOD) mouse as recipients. All five STZ BALB/c mice receiving microencapsulated islets (C57BL/6) maintained normoglycemia indefinitely. When NOD mice were used as recipients of the bioartificial pancreas, four of five grafts (islets from C3H/He) functioned for more than 80 d. Two of five NOD mice maintained normoglycemia until animals were sacrificed at 102 and 192 postoperative d. Microbeads made of commercially available agarose can effectively prolong alloislets functioning in the STZ-diabetic mouse and even in the NOD mouse (animal model of human type I diabetes) without the use of any immunosuppressive drug.

Animals↗
PubMed1992

Synthesis of antibiotic-loaded hydroxyapatite beads and in vitro drug release testing.

Various forms of hydroxyapatite (HAP) materials have been developed for use as bone grafts. Since the risk of local infection is associated with surgery, it seems reasonable to incorporate drugs such as antibiotics into implant materials. We therefore investigated the characteristics of drug incorporation into a spherical porous HAP bead (diameter = 8.48 mm, bulk porosity = 0.439) and its in vitro release behavior. Cefotiam (CTM) was used as a model antibiotic. Because of nonuniform pore distribution in the bead, distribution of CTM was estimated from the amounts of CTM experimentally determined at three different sites: the surface, halfway to the center, and the center of the beads. The results indicated that 90% of the drug was incorporated in the concentric outer 0.387 (radius = 1) section of the bead. CTM was released with a short lag time when the dry HAP bead was placed in water. Incorporation of CTM with egg phosphatidylcholine eliminated initial lag time and decreased the release rate of the drug from the bead. The lipid load was useful in controlling the release of CTM from the beads. In addition, to protect relatively unstable drugs from humidity and avoid contamination of drug-incorporated HAP beads an apparatus was designed with which the beads could be enclosed in vials in vacuo and under aseptic conditions on a bench-scale basis.

Bacterial Infections↗
PubMed1992

Symptoms of construction workers exposed to whole body vibration and local vibration.

To study the effects of construction machinery operation on subjective symptoms, a questionnaire survey was carried out among construction machinery operators by a self-reporting method. Subjects were 184 power shovel operators, 127 bulldozer operators, 44 forklift operators as operator groups, and 44 office workers as a control. Their ages were in a range of 30-49 years. The questionnaire contained 20 symptoms referring to fatigue, digestive problems, and upper or lower limbs or back problems. The prevalence rate and symptom characteristics were examined. The dominant symptoms of the operator groups were stiff shoulder, low back pain, and stomach symptoms. The prevalence rate of low back pain was significantly different between forklift operators and controls. No significant differences were found in the symptoms of upper limbs and fingers between operator groups and controls. The prevalence of Raynaud's phenomenon was 0.5%-2.3% in the operator groups and 2.3% in the control group.

Adult↗
PubMed1992

Hand-arm vibration syndrome and its prevalence in the present status of private forestry enterprises in Japan.

Currently there are no limitations on age of employment on private forestries in Japan. Hence, it was hypothesized that in these kind of enterprises, elderly chain saw operators, or those with long-term exposure, might be at higher risk of developing hand-arm vibration syndrome (HAVS). We consequently investigated the prevalence of HAVS in 447 chain saw workers on private forestries in Gifu Prefecture, Japan, with particular reference to age and exposure period. Of this population, 43 (9.6%) had signs and symptoms of vibration-induced white finger (VWF), and among these workers the severity of finger blanching was significantly correlated (P less than 0.01) with the exposure period. Classification of all subjects by exposure period showed that workers with greater than or equal to 30 years' exposure had higher prevalences of VWF (20.9%) and numbness of the hands (25.4%) compared to other groups. Significant differences (P less than 0.01) were found between the functional capacities of workers with VWF and those of control subjects. We concluded that (a) the elderly chain saw operators and those with longer exposure should be moved to other jobs with a lower or no risk of exposure to vibration, and (b) the results of screening tests, even without cold water immersion (which we did not employ, in order to protect workers' hands), could be helpful for the identification of workers with VWF.

Forestry↗
PubMed1992

The natural course of osteoarthritis of the hip due to subluxation or acetabular dysplasia.

In 59 patients, 86 hips with subluxation or hip dysplasia were examined to determine the natural course of the condition and select suitable treatment. Thirty-three percent of the joints (13/39 hips) developed early osteoarthritis from pre-osteoarthritis within an average term of 9.2 years, while the remaining, sixty-six percent (31/47 hips) developed advanced-stage osteoarthritis from early osteoarthritis within an average term of 7.8 years. Patients were classified into advanced and non-advanced groups according to radiographic analysis of the advanced groups according to radiographic analysis of the advance of the disease and statistical analysis was performed. In pre-osteoarthritis, centre-edge angle, slope of the acetabular roof, acetabular head index, acetabular depth ratio and Japanese Orthopaedic Association (JOA) hip score were significant predictors, while in early osteoarthritis, a broken Shenton's line, cranial joint space and JOA score were significant. On the basis of multiple parameters, formulas for predicting development in patients with pre-osteoarthritis, those with early osteoarthritis, and all patients together were established, with an accuracy of 87%, 71%, and 68%, respectively.

Acetabulum↗
PubMed1992

Evolutionary relationships among the gnat-transmitted orbiviruses that cause African horse sickness, bluetongue, and epizootic hemorrhagic disease as evidenced by their capsid protein sequences.

The amino acid sequences of four major capsid proteins of African horse sickness virus (serotype 4, AHSV-4) have been compared with those of Bluetongue virus of sheep. Epizootic hemorrhagic disease virus of deer, and the phylogenetic relationships established. Complete nucleotide sequence analysis of three RNA segments (L2, L3, and M6) of AHSV-4 and their encoded products, VP2, VP3, and VP5, together with previously published data for VP7 (Roy et al., 1991), have revealed that of the four capsid proteins the innermost protein, VP3, is the most conserved, and the outermost protein, VP2, is the most variable. Some 57-58% of the aligned BTV-10 and EHDV-1 VP3 amino acids are identical with those of AHSV-4. This compares to an identity of 79% between the BTV and EHDV VP3 sequences. For the VP7 proteins 64% of the aligned amino acids are identical between BTV-10 and EHDV-1, while they share 44-46% amino acid residues with the aligned VP7 protein of AHSV-4. By contrast, the VP2 proteins of the three viruses share only 19-24% identical amino acids. Various other comparative analyses of the proteins indicate that the VP2 species of the three orbiviruses are similar. Unlike VP2, the other outer capsid protein, VP5 is more conserved among the three viruses. On alignment, the VP5 of AHSV-4 has some 43-45% identical amino acids with that of BTV-10 and EHDV-1. Between BTV and EHDV, 62% of the aligned sequences are identical.

African Horse Sickness Virus↗
PubMed1992

IgM-producing renal plasmacytoma.

A seventy-six-year-old woman with plasmacytoma presenting as a renal mass died three months after diagnosis. Bone surveys disclosed no lytic lesions. Gallium-67 scan showed an avid uptake of the radionuclide in the renal mass. Histologic and immunofluorescence studies of resected specimens demonstrated that the renal parenchyma was destroyed by sheets of immature plasma cells producing IgM-lambda and by massive deposits of amorphous, eosinophilic substance stained with anti-mu and anti-lambda antisera. The literature is reviewed. We believe this case is the first one of well-documented IgM-producing renal plasmacytoma.

Aged↗
PubMed1992

Solidifying liquid with novel initiation system for detachable balloon catheters.

In endovascular surgery, to permanently hinder blood inflow into an aneurysm for example, a catheter is percutaneously introduced into an artery and the balloon is positioned and inflated by a solidifying liquid and then released into the diseased part. A novel solidifying liquid for the inflated balloon curable under the continuous feeding of oxygen through the wall of the balloon is described here. Glucose oxidase which oxidizes glucose producing hydrogen peroxide was used for polymerization of the solidifying liquid. This solidifying liquid cured even in the presence of oxygen and water. It was radiopaque when mixed with the iodinated X-ray contrast chemical iopamidol. In addition, the solidified liquid had appropriate mechanical properties. The endovascular surgery could be carried out safely using it.

Catheterization↗
PubMed1992

The activity of dipeptidyl peptidase II and dipeptidyl peptidase IV in mice immunized with type II collagen.

We investigated the activity of peptidases in the serum of mice with experimental polyarthritis that was induced by the injection of type II collagen, an experimental model of human rheumatoid arthritis. The activity of dipeptidyl peptidase II (DPP II) was increased and that of dipeptidyl peptidase IV (DPP IV) was decreased resulting in the significant increase of the serum DPP II/DPP IV ratio in the polyarthritic mice compared with that of controls. These results indicate that the DPP II/DPP IV ratio is a novel index of disease activity in mice with collagen-induced polyarthritis and may be useful in assessing the activity of rheumatoid arthritis in humans.

Animals↗
PubMed1992

Serial changes observed by magnetic resonance imaging in the intervertebral disc after chemonucleolysis. A consideration of the mechanism of chemonucleolysis.

Changes in the intervertebral disc after chemonucleolysis in 26 patients were observed by magnetic resonance imaging for 1 year, and from the results a mechanism for chemonucleolysis was considered. A reduction in size of the herniation was not recognized 2 weeks after treatment, when chymopapain had caused necrosis of the disc, but began after 4 weeks, when regeneration of the disc had occurred. The herniation was further reduced after 3 months, and the disc had become fibrocartilaginous in a cicatricial process. Marked decrease in disc signal was observed after 2 weeks, and never recovered. From these facts, it is considered that chymopapain might never cause primary diminution of disc herniation, and any reduction of herniation that occurs is due to the effects of a secondary cicatricial contraction.

Adolescent↗
PubMed1992

Characterization of the genes encoding two of the major capsid proteins of epizootic haemorrhagic disease virus indicates a close genetic relationship to bluetongue virus.

The sequences of the genes of two of the major capsid proteins of epizootic haemorrhagic disease virus serotype 1 (EHDV-1, Orbivirus genus, Reoviridae) have been determined by analyses of cDNA clones representing the L2 and S7 RNA segments. The EHDV-1 S7 RNA segment, which encodes the VP7 core protein, is 1162 nucleotides in length and has the capacity to encode 349 amino acids (M(r) 38,243). The EHDV-1 L2 RNA segment, which encodes the outer capsid VP2 protein (M(r) 113,249) is 2968 nucleotides in length and has an open reading frame of 971 codons. The potential secondary structure of the EHDV-1 S7 mRNA species, in particular that of the terminal regions, is comparable to those of the corresponding segments of bluetongue virus (BTV) and African horse sickness virus (AHSV); the EHDV-1 L2 mRNA species has a secondary structure similar to that of the L2 mRNA of BTV. The EHDV-1 VP2 and VP7 proteins, as well as those of the other two major structural proteins of EHDV published previously (the inner core VP3 protein and the second outer capsid, VP5), are closely related to the corresponding proteins of BTV. The EHDV and BTV VP7 sequences are more distantly related to the sequence of the AHSV VP7 protein published recently.

Amino Acid Sequence↗
PubMed1992

Estrogen receptor, c-erbB-2 and nm23/NDP kinase expression in the intraductal and invasive components of human breast cancers.

Expression of the c-erbB-2 oncoprotein (ErbB-2) and the nm23 anti-metastatic gene product (nucleoside diphosphate [NDP] kinase) was examined in the intraductal and invasive components of 63 fresh human breast cancer tissues. The expression of estrogen receptor (ER) as a marker of hormone dependency and the Ki-67 protein as a proliferative cell marker was also examined. ErbB-2 and ER were positive in 77.8% (28/36) and 64.7% (22/34) of the intraductal components, and in 43.6% (27/62) and 57.1% (36/63) of the invasive components, respectively. NDP kinase was positive in 58% (18/31) of intraductal, and in 30.9% (17/55) of invasive areas. The average Ki-67-positive cell rates were 5.9% in the intraductal, and 10.7% in the invasive components. Thus, the cells within the intraductal component of breast cancer appear to have different characteristics from the invasive component, not only in markers of proliferative ability, but also in the expression of oncogenes and hormone receptors.

Biomarkers, Tumor↗
PubMed1992

Effects of long-term oral administration of amiodarone on the electromechanical performance of rabbit ventricular muscle.

1. The effects of long-term administration of oral amiodarone on transmembrane action potential and contraction of ventricular muscle were investigated in rabbits. 2. ECGs of rabbits that received oral amiodarone 50 mg or 100 mg kg-1 daily for 4 weeks, showed a significant prolongation of RR, QT and corrected QT (QTc) intervals, whereas PQ and QRS were unaffected. Serum and myocardial tissue amiodarone concentrations were 0.14-0.18 micrograms ml-1 and 1.47-3.63 micrograms g-1 wet wt. respectively. 3. Right ventricular papillary muscles isolated from treated rabbits were characterized by a moderate prolongation of action potential duration (APD) compared with controls. A slight decrease of the maximum upstroke velocity (Vmax) was also observed at the higher dose. The APD prolongation by chronic amiodarone, unlike acute effects of sotalol, E-4031, Cs+ and 4-aminopyridine, did not show marked reverse use-dependence. 4. APD and Vmax restitution following slow basic stimuli (0.03 Hz) were unaffected by chronic treatment with amiodarone. 5. Acute application of amiodarone (10 microM) caused a significant decrease in APD and developed tension, as well as a marked use-dependent Vmax inhibition with fast recovery kinetics. 6. These findings suggest that a major and consistent electro-physiological effect of chronic amiodarone is repolarization delay (Class-III action) showing minimal frequency-dependence. However, when amiodarone above a certain concentration is present in the extracellular space, a fast kinetic Class-I action would be added as an acute effect.

Action Potentials↗
PubMed1992

[Detection of Neisseria gonorrhoeae in first-voided urine sediments from male urethritis patients by polymerase chain reaction].

Neisseria gonorrhoeae was detected from first-voided urine sediments of male patients with urethritis by polymerase chain reaction (PCR). Urine and urinary sediment were treated with proteinase K, and DNA was further purified by phenol extraction. Two oligonucleotides based on sequences within a ribosomal RNA gene from N. gonorrhoeae were used as primers for the PCR. A DNA fragment of 206 bp specific for N. gonorrhoeae was amplified by PCR and detected by agarose gel electrophoresis. In 19 specimens of urine sediments collected from 21 patients in whom N. gonorrhoeae was isolated from urethral swab by culture, 206 bp DNA fragment was amplified by PCR. In all specimens of urine sediments from 24 patients in whom cultures for N. gonorrhoeae were negative, no DNA was amplified by the PCR. The overall coincidence rate between the PCR for detecting N. gonorrhoeae in first-voided urine sediments and culture in urethral swab was 95.6% (43/45). PCR procedure for detection of pathogens from first-voided urine sediments would be noninvasive and would be applied for the diagnosis of gonococcal urethritis and chlamydial urethritis.

Chlamydia trachomatis↗