Search PubMed⌕ Search

Biomedical subjects

K Sakata

Publications and source records attributed to K Sakata.

At least 109 records · Page 6Linked to original sources
PubMed2000

Delayed CSF pseudocyst following shunt malfunction after myelomeningocele repair.

We report a case of delayed cerebrospinal fluid (CSF) pseudocyst following shunt malfunction in a 20-year-old patient with myelomeningocele. Magnetic resonance (MR) images and a radioimmunoassay shunt-gram detected the CSF fistula at the old scar of the myelomeningocele repaired 20 years before. Since the revision of the shunt system failed to keep the pseudocyst, the lesion was successfully directly repaired. Treatment of the delayed CSF pseudocyst following shunt malfunction thus requires a radical operation of the lesion.

Adult↗
PubMed2000

[Usefulness of the urea method in nasal discharge analysis].

We examined urea used as a dilution marker of broncho-alveolar lavage fluid to determine whether it was also useful as a dilution marker of nasal lavage fluid. We measured the concentration of urea in nasal secretions and peripheral blood for 91 cases. As a comparison, we also measured the total protein and albumin in nasal secretions and peripheral blood. The urea concentrations in nasal secretions were strongly correlated with that in peripheral blood (coefficient of correlation 0.925). The urea concentration in nasal secretions was approximately 2.4 times higher than the level in peripheral blood. No correlation was observed between total protein or albumin levels in nasal secretions and those in peripheral blood. In two patients with Japanese cedar pollinosis, we measured histamine concentration in nasal lavage fluid. Although no change in histamine concentration was observed by direct measurement, after the values were corrected for urea level, an increase in histamine was clearly observed during the cedar pollen season. The urea method was found to be useful as a dilution marker for nasal lavage fluid.

Adult↗
PubMed2000

Altered synaptic transmission in the hippocampus of the castrated male mouse is reversed by testosterone replacement.

PURPOSE: To determine the effect of castration on hippocampal function, we have investigated synaptic transmission in the castrated male mouse in vivo. We also examined whether administering testosterone can reverse the changes. MATERIALS AND METHODS: Male 12 weeks-old C57BL/6J mice were divided into three experimental groups; sham-castration (Control), the castration group (Cast), and the castration plus testosterone propionate group (Cast+TP). Field excitatory postsynaptic potentials (fEPSP) were evoked in the CA1 area of the hippocampus by stimulating the commissural fibers of the contralateral hippocampus. Field EPSPs were evoked in the granular cells of the dentate gyrus (DG) by stimulating the ipsilateral perforant path fibers. RESULTS: Laminar analysis of the fEPSPs in the hippocampal CA1 pyramidal cell layer did not differ significantly between the three experimental groups. However, paired pulse facilitation (PPF) of the fEPSP with short inter-stimulus intervals (30 to 100 msec) was significantly suppressed in Cast group. This suppression was reversed by testosterone injection (Cast+TP). Longterm potentiation (LTP) in the CA1 pyramidal neurons by high frequency stimulation (HFS) did not differ significantly between the three experimental groups, whereas potentiation evoked by primed burst stimulation (PBS) was much weaker in the Cast group compared with the Control group. Testosterone injection restored the PBS-induced potentiation to the control level. Synaptic transmission between perforant pathway and the granule cells in the dentate gyrus (DG) did not differ significantly among the three experimental groups. CONCLUSIONS: Suppression of PPF and impairment of the potentiation by PBS in CA1 hippocampal neurons was observed in castrated male mice and these changes were reversed by testosterone injection. These findings suggest that altered synaptic transmission in the castrated male mouse is caused by disturbance of inhibitory neuronal networks that are influenced by testosterone.

Animals↗
PubMed2000

Expression of matrix metalloproteinases (MMP-2, MMP-9, MT1-MMP) and their inhibitors (TIMP-1, TIMP-2) in common epithelial tumors of the ovary.

Matrix metalloproteinases (MMPs) are known to play an important role in cancer cell invasion by mediating the degradation of extracellular matrix proteins. The activity of such MMPs are regulated by tissue inhibitors of metalloproteinases (TIMPs). In this study, we investigated the immunohistochemical expression of MMP-2, MT1-MMP, TIMP-2, MMP-9, and TIMP-1 in 114 epithelial ovarian tumors (14 adenomas, 22 borderline tumors, and 78 adenocarcinomas). mRNA expression of MMP-2, MT1-MMP, and TIMP-2 was determined by RT-PCR in selected samples. The diffuse positive rates of MMP-2, MT1-MMP, TIMP-2, and MMP-9 in ovarian carcinomas were significantly higher than those in the borderline and in benign tumors. Conversely, the diffuse positive rate of TIMP-1 was higher in the benign and borderline ovarian tumors than that in ovarian carcinomas. The percentages of the cases with triple diffuse positive expression for MMP-2, MT1-MMP, and TIMP-2 within the same tumor was significantly higher in malignant tumors than those in borderline and in benign tumors. With respect to clinical stage, the triple diffuse positive rate in advanced-stage (stage II/III/IV) carcinomas was significantly higher than that in early-stage (stage I) carcinomas. A significantly higher triple diffuse positive rate was also observed in high-grade (grade 2/3) disease than in low-grade (grade 1) disease. Considerable levels of mRNA expression of MMP-2, MT1-MMP and TIMP-2 were detected in all selected samples that showed triple diffuse positive immunostaining, confirming the co-expression of MMP-2, MT1-MMP, and TIMP-2 at the transcriptional level within the same tumor. All cases with diffuse positive expression for MMP-9 showed regional or negative TIMP-1 expression. The diffuse positive rate of MMP-9 was significantly higher in ovarian carcinomas with lymph node metastasis than in those without lymph node metastasis. Our results suggest that the overexpression of MMP-2, MT1-MMP, TIMP-2, and MMP-9 and down-regulation of TIMP-1 may contribute to the development or enhanced growth capacity of ovarian tumors. Co-expression of MMP-2, MT1-MMP, and TIMP-2 within the same tumor seems to play an important role in the progression of ovarian cancer. Elevated MMP-9 expression together with low expression of TIMP-1 may also contribute to the lymph node metastasis of ovarian carcinoma cells.

Female↗
PubMed2000

Effects of cilnidipine on lipids, lipoproteins and fibrinolytic system in hypertensive patients.

Sixteen Japanese patients of both sexes aged 46-78 years with essential hypertension were studied at the cardiac clinic of the Department of Cardiology, Shizuoka General Hospital, Shizuoka, Japan. Serum lipids, lipoproteins, plasma fibrinolytic parameters, renin and noradrenaline were determined before and after 3 months of cilnidipine treatment. Systolic and diastolic blood pressures and heart rate were reduced while renin and noradrenaline levels remained unchanged after cilnidipine treatment. Total cholesterol and tissue plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1) and t-PA-PAI-1 complex were reduced. Changes in the other lipids, lipoproteins and fibrinolytic parameters were not significant after cilnidipine treatment. A negative correlation was found between low-density lipoprotein cholesterol and t-PA antigen levels after cilnidipine treatment. In conclusion, cilnidipine was effective for the treatment of hypertension and did not cause reflex tachycardia in Japanese patients. Cilnidipine treatment produced a beneficial lipid profile (decrease in total cholesterol), but did not show a consistent effect on fibrinolytic parameters in hypertensive patients. The metabolic interaction between beneficial lipid changes and fibrinolysis will be of value to better our understanding of the antiatherogenic effects of cilnidipine treatment in hypertensive patients.

Aged↗
PubMed2000

Clinicocytopathological and immunohistochemical study of adenoma malignum of the uterine cervix.

Adenoma malignum is a rare type of very highly differentiated adenocarcinoma of the uterine cervix, and is quite difficult to diagnose because there are few findings definitely suggesting malignancy on cytologic or histologic examination. We recently encountered four patients with adenoma malignum and reviewed their clinicocytopathological and immunohistochemical findings. The most characteristic symptom was a watery discharge and an enlarged cervix was palpable, while multiple cystic lesions (MCL) were observed by transvaginal and abdominal ultrasonography, CT or MRI. On cytodiagnosis, the cervical gland cells formed large sheets or showed a palisading arrangement. Slightly enlarged nuclei and yellowish-orange staining of the cytoplasmic mucus were the characteristic findings. On histological examination, many cervical glands of different sizes were present and extended deep into the muscle layer, while branching or papillary growth into the lumen was also observed. On immunohistochemical study, HIK1083, a monoclonal antibody for gastric gland mucous cell mucin, was found to be positive in 3 of 4 cases, and this was fairly useful in the diagnosis of adenoma malignum.

Adenocarcinoma↗
PubMed2000

Rice at the forefront of plant genome informatics.

As rice genomicsdata continue to accumulate at a rapid rate, are becoming more valuable to warehouse and access large and rigorous data sets. This article gives an overview of available resources on rice bioinformatics and their role in elucidating and propagating biological and genomic information in rice. Of particular focus here is the informatics infrastructure developed at the Rice Genome Research Program (RGP) following an extensive rice genome analysis. The database named INE (Integrated Rice Genome Explorer) integrates the genetic and physical mapping information with the genome sequence being generated in collaboration with the International Rice Genome Sequencing Project (IRGSP). Database links are initially evaluated using an interoperable query tool to explore and compare data across the rice and maize genome databases and potential application to multiple crop database querying. A proposed logistics for interlinking these resources is presented to integrate, manipulate and analyze information on the rice genome. One of the biggest challenges of rice bioinformatics lies in the emerging role of rice as a model system among grass crop species. In view of the importance of comparative genetics in the formulation of new knowledge on plant genomes and genes, comparative bioinformatics remains an essential strategy to gain new insights on the needs and expectations on rice genomics.

Chromosome Mapping↗
PubMed1999

Involvement of ppGpp, ribosome modulation factor, and stationary phase-specific sigma factor sigma(S) in the decrease in cell viability caused by spermidine.

Accumulation of spermidine in Escherichia coli causes a decrease in cell viability at the late stationary phase of cell growth. The mechanism underlying this effect has been studied. Spermidine accumulation caused an increase in the level of ppGpp and a decrease in ribosome modulation factor (RMF) and stationary phase-specific sigma factor sigma(S), both of which are believed to be involved in cell viability. Transformation of E. coli with the gene for stringent factor, which synthesizes ppGpp, also caused a significant decrease in the levels of RMF and sigma(S) factor and a decrease in cell viability. The results strongly suggest that the accumulation of ppGpp is also involved in the decrease in cell viability and that the sigma(S) factor assists the function of RMF in cell viability.

Bacterial Proteins↗
PubMed1999

Modulation by L- and D-isoforms of amino acids of the L-glutamate response of N-methyl-D-aspartate receptors.

N-Methyl-D-aspartate (NMDA) receptor subtypes epsilon 1 and zeta 1 were coexpressed in Xenopus oocytes for the investigation of the magnitude of augmentation of the L-glutamate response by 20 common L-amino acids and their 19 D-isoforms. Simultaneous application of L- and D-alanine, -cysteine, and -serine, or glycine and L-glutamate potentiated the glutamate-induced current. Other amino acids produced only marginal effects. Analysis of the relationship between the response and amino acid size revealed that the critical threshold size is between those of cysteine and aspartate. No amino acid alone induced a current. The effects of L- and D-alanine, -cysteine, and -serine applied with L-glutamate were concentration-dependent. Molecular modeling of these three amino acids revealed a positive relationship between the charge at an atom of the side chain and the receptor sensitivity, which may explain the efficacies of these amino acids.

Alanine↗
PubMed1999

Differential inhibition by ferrous ions of [3H]MK-801 binding to native N-methyl-D-aspartate channel in neonatal and adult rat brains.

In vitro addition or pretreatment with >/=1 microM ferrous chloride markedly inhibited in a concentration-dependent manner [3H]dizocilpine (MK-801) binding to an open ion channel associated with the N-methyl-D-aspartate (NMDA) receptor in rat brain synaptic membranes. The addition of NMDA agonists invariably attenuated the inhibition of [3H]MK-801 binding in hippocampal synaptic membranes previously treated with ferrous chloride, without significantly affecting that in cerebellar synaptic membranes. In the absence of spermidine, ferrous chloride was more potent in inhibiting binding in the cerebral cortex and hippocampus in adult rats than in those in rats at 3 days after birth, while in the striatum [3H]MK-801 binding was 10 times more sensitive to inhibition by added ferrous chloride in neonatal rats than in adult rats. Addition of spermidine significantly attenuated the potency of ferrous chloride to inhibit binding in the cerebral cortex of adult rats, with facilitation of the inhibition in newborn rats. Moreover, spermidine significantly reduced the inhibitory potency of ferrous chloride in neonatal rat striatum, without markedly affecting that in adult rat striatum. These results suggest that ferrous ions may interfere with opening processes of the native NMDA channel through molecular mechanisms peculiar to neuronal development in a manner associated with the polyamine recognition domain.

Animals↗
PubMed1999

Identification of a gene for a polyamine transport protein in yeast.

Properties of a membrane protein encoded by YLL028w were examined using yeast cells transformed with the gene. The transformed cells became resistant to polyamine toxicity, and the resistance was overcome by bafilomycin A1, an inhibitor of vacuolar H+-ATPase. Although spermine uptake activity of the transformed cells was almost the same as that of wild type cells, the uptake activity of vacuolar membrane vesicles from the transformed cells was higher than that from wild type cells. The transformed cells became resistant to MGBG (methylglyoxal bis(guanylhydrazone)) and paraquat, but not Ni2+ and Co2+, suggesting that the protein encoded by YLL028w is a transport protein specific for polyamines. When the YLL028w gene was disrupted by inserting the HIS3 gene, the cells became sensitive to polyamines, and spermine uptake activity of the vacuolar membrane vesicles decreased significantly. The accumulated spermine in YLL028w gene-disrupted cells decreased greatly compared with that in wild type cells. The results indicate that a membrane protein encoded by YLL028w (TPO1) is a polyamine transport protein on the vacuolar membrane.

Base Sequence↗
PubMed1999

Cloning of a bovine orphan transporter and its short splicing variant.

We have isolated a cDNA (bv7-3) encoding a member of the Na+,Cl(-)-dependent transporter family and its short splicing variant (bv7-3s) by screening a bovine retina cDNA library. Sequence analysis revealed that bv7-3 encodes a protein of 729 amino acids and is a bovine homologue of the rat orphan transporter v7-3-2. bv7-3s contains 265 amino acids, sharing 252 N-terminal amino acids with bv7-3. Both mRNAs for bv7-3 and bv7-3s were detected in nervous system by Northern blot analysis. In immunofluorescence analysis in transfected HEK 293T cells, myc-tagged bv7-3 was mainly detected on the plasma membrane, whereas myc-tagged bv7-3s showed a pattern of intracellular membrane staining.

Alternative Splicing↗
PubMed1999

Prognostic factors of nasopharynx tumors investigated by MR imaging and the value of MR imaging in the newly published TNM staging.

PURPOSE: To examine the usefulness of MR imaging for predicting local control of nasopharyngeal carcinoma (NPC) and the value of MR imaging in the newly published fifth edition of the TNM classification. METHODS AND MATERIALS: We studied 29 patients with NPC with MR imaging and CT before and after treatment. Staging was done according to the fourth and newly published fifth editions of the International Union Against Cancer (UICC) staging system. The radiotherapy protocol was designed to deliver 66 to 68 Gy to the primary tumor and clinically involved nodes. RESULTS: MR proved better than CT at identifying obliteration of the pharyngobasilar fascia, invasion of the sinus of Morgagni, through which the cartilaginous portion of the eustachian tube and the levator veli palatini muscle pass, invasion of the skull base, and metastases to lymph nodes in the carotid and retropharyngeal spaces. All seven patients without invasion of the pharyngobasilar fascia had local control. The local control rates of patients with invasion of the skull base were not good (60 to 73%). There was no apparent relationship between tumor volume determined by T1-weighted MR images and local control when the tumor volume was more than 20 cc. The newly published N staging system appears to successfully identify the high-risk group for distant metastasis as N3. In our series, four of five patients with N3 disease developed distant metastases. CONCLUSION: Deep infiltration of the tumor is a more important prognostic factor in NPC than tumor volume. Since the newly published T staging system requires a search for tumor invasion into soft tissue such as parapharyngeal space and bony structures, MR imaging may be indispensable for the newly published NPC staging system.

Adolescent↗
PubMed1999

Propensity of ectopic liver to hepatocarcinogenesis: case reports and a review of the literature.

Two patients with ectopic liver are described. In one patient, a small ectopic liver attached to the gastric serosa developed hepatocellular carcinoma (HCC). The preoperative diagnosis was an alpha-fetoprotein (AFP)-producing carcinoma and a malignant ulcer of the stomach. Total gastrectomy and esophago-jejunostomy were performed. The tumor that measured 4 x 2 x 2 cm contained an AFP-producing HCC and normal liver tissue. In another patient who had alcoholic cirrhosis, ectopic liver on the serosa of the gallbladder was found to have the same histological changes as the mother liver. A survey of the literature disclosed more than 20 cases in which HCC developed outside the liver; the liver did not have HCC. By contrast, there was only one report on HCC occurring in the liver in the presence of a noncancerous, relatively large accessory liver lobe. Because ectopic liver does not have a complete vascular and ductal system as a normal liver, it is perhaps functionally handicapped and more prone to hepatocarcinogenesis.

Carcinoma, Hepatocellular↗