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Biomedical subjects

K Kuroda

Publications and source records attributed to K Kuroda.

At least 73 records · Page 4Linked to original sources
PubMed2000

Prenatal evaluation of cephalopagus conjoined twins by means of three-dimensional ultrasound at 13 weeks of pregnancy.

Cephalopagus twinning, an extremely rare type of conjoined twins, is characterized by the anterior union of the upper half of the body, with two faces each situated on the opposite side of a conjoined head. The prognosis for cephalopagus twins is extremely poor because surgical separation is not an option. Thus early prenatal diagnosis of cephalopagus twins is important to provide an opportunity for pregnancy termination if desired. However, in many instances, cephalopagus twins are misdiagnosed as a singleton pregnancy because of the extreme degree of fusion which makes accurate demonstration of the abnormalities very difficult. This report presents a case of cephalopagus twins which was confirmed at 13 weeks of gestation using three-dimensional ultrasound.

Adult↗
PubMed2000

Basement membrane alterations in psoriasis are accompanied by epidermal overexpression of MMP-2 and its inhibitor TIMP-2.

Psoriasis is most probably an inherited disease characterized by cell proliferation, angiogenesis, and an inflammatory process. The pathophysiology remains unknown, although an alteration in cell-cell and cell-matrix adhesion versus an autoimmune process has been proposed as the primary defect. Here, we show evidence of a new mechanism involving basement membrane alterations accompanied by keratinocyte overexpression of matrix metalloproteinase (MMP) 2 and tissue inhibitor of MMP-2 (TIMP-2) in both uninvolved and involved psoriatic skin. Immunocytochemistry with antibodies against collagen IV (alpha1, alpha2 chains) and laminins (alpha2, alpha5, beta1, gamma1 chains) revealed gaps, folding, and reduplication of the epidermo-dermal basement membrane. There was overexpression of MMP-2 in the cytoplasm of suprabasal keratinocytes. Gelatin zymography revealed pro-MMP-2 and its activated form, a-MMP-2, in both uninvolved and involved psoriatic skin, whereas pro-MMP-9 was only present in involved skin. TIMP-2 was expressed at the cell surface of psoriatic involved suprabasal keratinocytes whereas it was restricted to basal keratinocytes in uninvolved areas. Western blots showed a marked increase in a-MMP-2 and TIMP-2 in uninvolved and involved psoriatic skin although it was more pronounced in the latter. MT1-MP, known to activate pro-MMP-2, was increased in involved areas. In situ hybridization revealed strong signals of MMP-2 mRNA in both uninvolved and involved psoriatic epidermis. The overexpression of MMP-2 in uninvolved and involved psoriatic epidermis supports the concept that the primary alteration may reside in the keratinocyte. In addition, the presence of the activated form of MMP-2 could be responsible for cell-cell and cell-matrix changes noted in psoriatic epidermis.

Basement Membrane↗
PubMed2000

Diazepam-binding inhibitor-like activity in rat cerebrospinal fluid after stimulation by an aversive quinine taste.

Cerebrospinal fluid (CSF) taken from rats after stimulation by an aversive quinine taste (hereafter called quinine CSF) administered into the fourth ventricle of mice suppressed their intake of 5% sucrose solution. We examined the effects of CSF on glutathione-induced tentacle ball formation (TBF) of hydra to determine the change in CSF components associated with aversive taste stimuli. The suppressive activity of quinine CSF on TBF in the presence of 3 microM S:-methyl-glutathione (GSM) was markedly lower than that of CSF obtained from control rats (control CSF). Pronase-treated quinine CSF had suppressive activity similar to that of control CSF. The active principle passed through an ultrafiltration membrane, with a molecular weight cut-off of 30 kDa, but not through one with a cut-off of 3 kDa. A peptide fragment of diazepam-binding inhibitor (DBI) nullified the suppression of TBF at 3 microM GSM by control CSF. The nullifying activity of quinine CSF was not observed after treatment with a benzodiazepine receptor preparation that was able to bind DBI. When flumazenil, a benzodiazepine receptor antagonist, was given to mice, the suppression of the intake of 5% sucrose solution by quinine CSF was partially reversed. It is suggested that quinine CSF contains a DBI-like substance.

Animals↗
PubMed2000

Binding of influenza type A viruses to group B Streptococcus and haemagglutination by virus-bound bacteria.

We studied the bindings of human influenza A type viruses to group B Streptococcus (GBS), types Ia, II, III and IV, of sialic acid (SA)alpha2-3 linkage, using A/PR/8/34(H1N1) and A/Memphis/1/71(H3N2). The viruses were found to bind to all types of GBS, with the exception of PR/8/34 for GBSII, and to elute from GBSIa, III and IV at 37 degrees C, except GBSII. Electron microscopy confirmed these behaviours of the influenza viruses. The virus-binding capability of GBS types seemed to depend on the side chain length of the terminal SA. Treatment of GBSIa, III and IV, except enzyme-resistant type II, with bacterial neuraminidase resulted in the loss of virus-binding capability of GBS. These findings confirmed that SAalpha2-3 linkage of GBS capsules functions as receptor for human influenza viruses. When singular bacteria were prepared from mainly chain-like GBS with sonication, viruses were found to bind to them more efficiently. Untreated and sonicated GBS were both aggregated with high doses of virus. Furthermore, using A/Memphis/1/71(H3N2) and GBSII, we found that virus-bound GBS, untreated or sonicated, caused haemagglutination (HA). The morphological evidence that chicken erythrocytes were bridged with virus-bound native GBSII, supporting occurrences of HA, was obtained. Statistical analysis suggested that HA by virus-bound sonicated (singular) GBS was mediated by bacteria bound by at least two or three virus particles.

Animals↗
PubMed2000

Specific accumulation of polysaccharide-linked hydroxycinnamoyl esters in the cell walls of irregularly shaped and collapsed internode parenchyma cells of the dwarf rice mutant Fukei 71.

We examined a novel rice mutant, Fukei 71 (Oryza sativa L.), for alterations in the levels of hydroxycinnamoyl esters that are linked to cell wall polysaccharides and lignin units. In this mutant, a recessive mutation at a single locus caused the collapse of parenchyma cells in the internodes. Light microscopy revealed that the abnormal walls of internode parenchyma cells of Fukei 71 were stained by the Mäule reaction, which is specific for syringyl units in phenolic compounds. These walls were not stained by Wiesner's reagent (phloroglucinol-HCl), which reacts cinnamaldehyde in lignin. Levels of p-coumaric acid (PCA) and ferulic acid (FA) were apparently elevated in the abnormal tissue of the mutant. Western blotting analysis with antibodies specific for phenylalanine ammonia-lyase (PAL) revealed higher levels of PAL in the abnormal parenchyma tissue of Fukei 71 than in the parenchyma tissue of the parent cultivar Fujiminori. These results and the observation that PAL was produced at a greatly elevated level indicated that the phenylpropanoid pathway that leads to the biosynthesis of polysaccharide-linked FA and PCA was abnormally activated in the irregularly shaped and collapsed internode parenchyma cells, in which the biosynthesis of lignin is normally repressed.

Cell Wall↗
PubMed2000

Preferential activity of wild-type and mutant tumor necrosis factor-alpha against tumor-derived endothelial-like cells.

Tumor-derived endothelial-like cells (tEC) were prepared by culturing human umbilical vein endothelial cells (HUVEC) in the presence of HT1080 human fibrosarcoma-conditioned medium. tEC showed higher permeability and less cell-adhesion activity than normal HUVEC (nEC). Tumor necrosis factor-alpha (TNF) is known to have tumor-vasculature disrupting activity. tEC showed higher cytotoxicity to recombinant human TNF (rhTNF) than nEC, and was not observed using HUVEC cultured with WI38 human diploid cell-conditioned medium as a medium-control. These results demonstrate that tEC acquire physiological properties of tumor-associated vasculature, and may be a useful model system for the study of the mechanisms of TNF antitumor action. The TNF-mutant RGD-V29 (code No. F4614), which has an inserted 4Arg-Gly-Asp sequence and an 29Arg-->Val replacement, was found to induce greater preferential destruction of tEC compared to rhTNF. When the preferential activities were evaluated in terms of 30% cytotoxicity (IC30) ratio (nEC/tEC), the ratio was 460 for RGD-V29 compared to 4.2 for rhTNF. RGD-V29 also exhibited cell-adhesive function and bound preferentially to the p55 TNF-receptor. Both these properties of RGD-V29 contributed to the tEC selective cytotoxicity, indicating that the RGD ligands and selective p55 receptor binding on the cells, although uncharacterized, are involved in tEC targeting. Therefore, the TNF mutant RGD-V29 may show greater selectivity toward tumor vasculature than wild-type TNF.

Binding, Competitive↗
PubMed2000

Costello syndrome with decreased gene expression of elastin in cultured dermal fibroblasts.

We report a case of Costello syndrome. A 2-year-old Japanese boy presented with a 'coarse' face, curly hair and loose skin of the dorsal aspect of the hands and feet with dark pigmentation. A skin biopsy of the dorsal aspect of the left hand revealed hyperkeratosis and papillomatosis of the epidermis, hyperpigmentation of the basal layer, and shortening and rupture of elastic fibers of the dermis. Electron microscopy of dermal elastic fibers showed a decreased amount of elastin with an exposed appearance of microfibrils. In Northern blot analysis of cultured dermal fibroblasts, elastin mRNA levels were reduced, suggesting a decrease in elastin production at the lesions of loose skin.

Abnormalities, Multiple↗
PubMed2000

Biochemical studies of dopaminergic activation by stimuli of corn oil in the oral cavity in mice.

We investigated the effects of corn oil stimuli in the oral cavity on monoaminergic neurones by measuring the amount of monoamines and their metabolites in brains of mice. Intraoral injection of corn oil (0.1 ml) increased dopamine (DA) turnover rate in the cortex 3, 5 and 10 min after injection in mice. A significant increase of DA turnover rate was also observed in midbrain 10 min after the corn oil injection. Turnover rates of noradrenaline (NA) and serotonin (5-HT) were not affected by the corn oil injection in any of the regions or times tested. In the chronic study, DA and 5-HT contents in the left and right cortexes and 5-HT contents in diencephalon in the chronic corn oil-fed group were significantly higher than those in the-control but NA contents were not significantly different between the two groups in all regions. In conclusion, the present results suggested that the stimuli of corn oil in the oral cavity might activate dopaminergic systems in the brain of mice and its chronic stimuli might increase DA contents in the brain. Although 5-HT contents increased in the brains of mice by the chronic corn oil intake, its physiological implication remains to be elucidated.

Animals↗
PubMed2000

Simple and rapid determination of Gtpase activity by capillary electrophoresis without radioisotope.

In order to determine guanosine-5'-triphosphatase (GTPase) activity, we developed a simple, rapid and reliable method that utilizes capillary electrophoresis without radioisotope. Tubulin-GTPase was used for simple measurement of GTPase activity utilizing capillary electrophoresis. Tubulin, a component of microtubules, was incubated with guanosine-5'-triphosphate (GTP) in 100 mM 2-(N-morpholino) ethanesulfonic acid (MES) buffer (pH 6.5). Guanosine-5'-diphosphate (GDP) was determined as the hydrolyzed product of GTP. Guanosine-5'-monophosphate, GDP and GTP in the filtrate of the mixture were clearly separated using 10 mM MES buffer (pH 6.5) (migration time, 3.8, 5.5 and 7.2 minutes, respectively) with a fused-silica capillary column. The quantification of GDP was based on the peak area, which increased linearly with the concentration of GDP from 1 to 50 microM (r2=0.995). The peak area and migration time had good reproducibility; the intra-assay coefficient of variation (n=6) was 1.3% for peak area and 0.6% for migration time. As an application of this method, we examined the effect of dimethylarsinic acid, an effective antimitotic agent, on tubulin-GTPase. Dimethylarsinic acid inhibited tubulin-GTPase activity in a dose-dependent manner. The inhibition was not complete and the maximum decrease of the activity was about 50% at 200 microM dimethylarsinic acid. Thus, since this method is clean, simple and rapid, its application to the study of various GTPase proteins is expected to be useful.

Buffers↗
PubMed2000

[A case of posttraumatic severe ventriculitis treated by intraventricular lavage].

A 44-year-old male was admitted in a state of semicoma, tonic convulsion and elevated body temperature nine days after sustaining head injury. He had severe nuchal rigidity. Computed tomography revealed dilation of ventricles and swelling of the brain parenchyma. We performed cerebrospinal fluid (CSF) drainage of both lateral ventricles immediately. The fluid drained from both ventricles was just like pus. We diagnosed the patient's condition as posttraumatic ventriculitis and meningitis. We performed intraventricular lavage (IL) which was our ventricular irrigating technique. IL was repeated until the 7th day postoperatively. The CSF data improved immediately. Continuous spinal drainage (CSD) also was used for CSF drainage from the 7th day postoperatively. The patient recovered without the need for CSF shunt. Some authors have reported the usefulness of continuous intraventricular irrigation (CIVI) for treatment of severe ventriculitis. However, their patients required CSF shunt surgeries. Such shunts are likely to become infected more frequently than routine shunting. Our IL was able to drain pus and inflammatory products in the ventricles before the formation of septations in the ventricles. We emphasize that IL in combination with CSD is able to bring about good results for patients with severe ventriculitis.

Adult↗
PubMed2000

[A case of intracerebral and subarachnoid hemorrhage of unknown origin with preceding headache].

We report a case of a 31-year-old female with multiple intracerebral hemorrhage and subarachnoid hemorrhage. She presented with headache one week before hemorrhage, and a CT scan performed at that time showed no abnormal findings. Neurological examination on admission revealed mild disturbance of consciousness, papilledema, and mild left hemiparesis. CT scans demonstrated intracerebral hemorrhage in the right caudate head and left frontal subcortex, and diffuse subarachnoid hemorrhage. Cerebral angiogram and laboratory examination revealed no abnormal findings. Erythrocyte sedimentation rate, C reactive protein and antiphospholipid antibody were within normal ranges. The patient underwent removal of hematoma by craniotomy. One week after the operation, a subcutaneous hematoma in the area of the craniotomy was found. Cerebral angiography demonstrated an aneurysm of the right superficial temporal artery, which was remote from the craniotomy. This aneurysm was surgically removed and examined. Histopathological examination revealed the presence of a pseudoaneurysm but no inflammation. Although primary angitis of the central nervous system was suspected to be the cause of this disease, a definite diagnosis could not be obtained.

Adult↗
PubMed1999

Delta-induced Notch signaling mediated by RBP-J inhibits MyoD expression and myogenesis.

Signaling induced by interaction between the receptor Notch and its ligand Delta plays an important role in cell fate determination in vertebrates as well as invertebrates. Vertebrate Notch signaling has been investigated using its constitutively active form, i.e. the truncated intracellular region which is believed to mimic Notch-Delta signaling by interaction with a DNA-binding protein RBP-J. However, the molecular mechanism for Notch signaling triggered by ligand binding, which leads to inhibition of differentiation, is not clear. We have established a myeloma cell line expressing mouse Delta1 on its cell surface which can block muscle differentiation by co-culture with C2C12 muscle progenitor cells. We showed that Delta-induced Notch signaling stimulated transcriptional activation of RBP-J binding motif, containing promoters including the HES1 promoter. Furthermore, ligand-induced Notch signaling up-regulated HES1 mRNA expression within 1 h and subsequently reduced expression of MyoD mRNA. Since cycloheximide treatment did not inhibit induction of HES1 mRNA, the HES1 promoter appears to be a primary target of activated Notch. In addition, a transcriptionally active form of RBP-J, i.e. VP16-RBP-J, inhibited muscle differentiation of C2C12 cells by blocking the expression of MyoD protein. These results suggest that HES1 induction by the Delta1/Notch signaling is mediated by RBP-J and blocks myogenic differentiation of C2C12 cells by subsequent inhibition of MyoD expression.

Animals↗
PubMed1999

Phosphorylation and dephosphorylation of the B subunit of DNA polymerase alpha-primase complex in the early embryogenesis of Drosophila.

In the early embryos of Drosophila, the B subunit of the DNA polymerase alpha-primase complex was found to migrate more slowly during the first 13 mitotic cycles than that from cycle 14 using SDS-polyacrylamide gel electrophoresis. Lambda phosphatase treatment showed that the reduced migration was caused by phosphorylation of the B subunit. Detailed analysis using the partially purified B subunit indicated that most of the B subunit until cycle 13 was a phosphorylated form while the B subunit of cycle 14 was a dephosphorylated form.

Animals↗
PubMed1999

Seasonal changes in the freezing behavior of xylem ray parenchyma cells in four boreal hardwood species

The freezing behavior of xylem ray parenchyma cells in several boreal hardwood species, namely, Betula platyphylla, Populus canadensis, P. sieboldii, and Salix sachalinensis, was examined by differential thermal analysis (DTA), cryo-scanning electron microscopy (Cryo-SEM), and freeze-fracture replica electron microscopy. Although DTA profiles of samples harvested in summer and in winter suggested that the xylem ray parenchyma cells in all four species responded to freezing stress by extracellular freezing, Cryo-SEM showed clearly that the xylem ray parenchyma cells in all these species responded to freezing stress by shallow supercooling in summer and by extracellular freezing in winter. It is suggested that DTA failed to reveal the true freezing behavior of xylem ray parenchyma cells because of an overlap of temperature ranges between the high-temperature exotherm and the low-temperature exotherm and/or because of the limited extent of the LTE. The seasonal changes in freezing behavior of xylem ray parenchyma cells in all these boreal species, which are results of seasonal cold acclimation, support the hypothesis that a gradual shift of freezing behavior in xylem ray parenchyma cells from shallow supercooling in hardwood species that grow in tropical zones to extracellular freezing in hardwood species that grow in cold areas might be a result of the evolutionary adaptation of hardwood species to cold climates. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Comparison of p53 and bcl-2 expression in initial, synchronous, and metachronous colorectal adenomas.

To investigate the significance of p53 and bcl-2 expression in metachronous colorectal adenomas arising in the remaining colon after carcinoma resection, we analyzed p53 and bcl-2 expression immunohistochemically in initial adenomas (type I), synchronous adenomas with concurrent carcinoma (type II), and metachronous adenomas arising after resection of initial adenomas (type III) or carcinoma (type IV). The incidence of p53 immunoreactivity in type IV adenomas with mild dysplasia was significantly higher than that in type I, type II, or type III adenomas with mild dysplasia. bcl-2 immunoreactivity was more frequently detected in type IV adenomas with mild dysplasia than in type I or type III adenomas with mild dysplasia. Coexpression of p53 and bcl-2 was detected in 16% of the type IV adenomas, this being a significantly higher frequency than that seen in the type I, type II, or type III adenomas. These results suggest that the evaluation of p53 and bcl-2 in metachronous adenomas in the remaining colon after resection of carcinoma may be a useful biologic marker for assessing the risk of cancer development.

Adenoma↗
PubMed1999

A case of spinocerebellar ataxia type 6 mimicking olivopontocerebellar atrophy.

Spinocerebellar ataxia type 6 (SCA6) is an autosomal dominant, slowly progressive cerebellar ataxia without multisystem involvement. We report a 57-year-old woman with genetically confirmed SCA6 who showed clinical features of olivopontocerebellar atrophy. Conventional T2-weighted and FLAIR MRI demonstrated high signal in the middle cerebellar peduncles, in addition to mild atrophy of the pons and cerebellum.

Female↗