Biomedical subjects

Y Sakai

Publications and source records attributed to Y Sakai.

At least 217 records · Page 12Linked to original sources

PubMed1999

Organization of the genes involved in the ribulose monophosphate pathway in an obligate methylotrophic bacterium, Methylomonas aminofaciens 77a.

The 4.4-kb PstI fragment harboring the gene encoding 3-hexulose-6-phosphate synthase, rmpA, which was previously cloned from the chromosome of an obligate methylotroph, Methylomonas aminofaciens 77a, was investigated in detail. In addition to the rmpA gene, the fragment contained three open reading frames encoding transaldolase (rmpD), IS10-R (rmpI), and 6-phospho-3-hexuloisomerase (PHI) (rmpB). The rmpB gene product was overproduced in Escherichia coli cells, purified to homogeneity, and then enzymatically identified as PHI. The gene organization of the ribulose monophosphate pathway enzymes together with a transposon, IS10-R, is discussed from both evolutionary and regulatory aspects.

Aldehyde-Lyases↗

PubMed1999

The Ornstein-Uhlenbeck process does not reproduce spiking statistics of neurons in prefrontal cortex.

Cortical neurons of behaving animals generate irregular spike sequences. Recently, there has been a heated discussion about the origin of this irregularity. Softky and Koch (1993) pointed out the inability of standard single-neuron models to reproduce the irregularity of the observed spike sequences when the model parameters are chosen within a certain range that they consider to be plausible. Shadlen and Newsome (1994), on the other hand, demonstrated that a standard leaky integrate-and-fire model can reproduce the irregularity if the inhibition is balanced with the excitation. Motivated by this discussion, we attempted to determine whether the Ornstein-Uhlenbeck process, which is naturally derived from the leaky integration assumption, can in fact reproduce higher-order statistics of biological data. For this purpose, we consider actual neuronal spike sequences recorded from the monkey prefrontal cortex to calculate the higher-order statistics of the interspike intervals. Consistency of the data with the model is examined on the basis of the coefficient of variation and the skewness coefficient, which are, respectively, a measure of the spiking irregularity and a measure of the asymmetry of the interval distribution. It is found that the biological data are not consistent with the model if the model time constant assumes a value within a certain range believed to cover all reasonable values. This fact suggests that the leaky integrate-and-fire model with the assumption of uncorrelated inputs is not adequate to account for the spiking in at least some cortical neurons.

Action Potentials↗

PubMed1999

Isolation and characterization of a mouse SRY-related cDNA, mSox7.

SOX is a family of SRY-related genes, which encode transcriptional factors involved in development. In this study, we newly isolated and sequenced mouse cDNA clones for mSox7. The mSox7 gene encodes 380 amino acids containing an SRY-type HMG box. Genomic Southern analysis suggested that the mSox7 gene was a single-copy gene. Tissue specific expression of mSox7 was investigated by Northern analysis. The expression was restricted to the ovary and heart, and the size of the transcripts was estimated to be 3.6 knt. Electrophoretic mobility shift assay indicated that recombinant mSox7 polypeptide was capable of binding to a nucleotide sequence, AACAAT. Immunohistochemical study revealed that mSox7 protein was localized in oocytes in the mouse ovary.

Amino Acid Sequence↗

PubMed1999

Molecular cloning of a novel human collectin from liver (CL-L1).

Collectins are a C-lectin family with collagen-like sequences and carbohydrate recognition domains. These proteins can bind to carbohydrate antigens of microorganisms and inhibit their infection by direct neutralization and agglutination, the activation of complement through the lectin pathway, and opsonization by collectin receptors. Here we report the cloning of a cDNA encoding human collectin from liver (CL-L1 (collectin liver 1)) that has typical collectin structural characteristics, consisting of an N-terminal cysteine-rich domain, a collagen-like domain, a neck domain, and a carbohydrate recognition domain. The cDNA has an insert of 831 base pairs coding for a protein of 277 amino acid residues. The deduced amino acid sequence shows that this collectin has a unique repeat of four lysine residues in its C-terminal area. Northern blot, Western blot, and reverse transcription-polymerase chain reaction analyses showed that CL-L1 is present mainly in liver as a cytosolic protein and at low levels in placenta. More sensitive analyses by reverse transcription-polymerase chain reactions showed that most tissues (except skeletal muscle) have CL-L1 mRNA. Zoo-blot analysis indicated that CL-L1 is limited to mammals and birds. A chromosomal localization study indicated that the CL-L1 gene localizes to chromosome 8q23-q24.1, different from chromosome 10 of other human collectin genes. Expression studies of fusion proteins lacking the collagen and N-terminal domains produced in Escherichia coli affirmed that CL-L1 binds mannose weakly. CL-L1 and recombinant CL-L1 fusion proteins do not bind to mannan columns. Analysis of the phylogenetic tree of CL-L1 and other collectins indicated that CL-L1 belongs to a fourth subfamily of collectins following the mannan-binding protein, surfactant protein A, and surfactant protein D subfamilies including bovine conglutinin and collectin-43 (CL-43). These findings indicate that CL-L1 may be involved in different biological functions.

Amino Acid Sequence↗

PubMed1999

Molecular cloning and expression of Xenopus laevis requiem cDNA1.

Requiem is an apoptosis-associated gene, which was originally identified in mouse (T.G. Gabig et al., J. Biol. Chem. 269 (1994) 29515-29519). In this study, we isolated five independent cDNA clones for frog Requiem (xReq) from Xenopus laevis ovary. Sequence analysis of the multiple cDNAs has suggested that Xenopus genome contains at least two non-allelic copies of the xReq gene. The amino acid sequence deduced from the cDNAs contained a single Krüppel-type zinc-finger motif and two PHD-finger motifs. Northern analysis revealed that the ovary expressed xReq transcripts with different sizes.

Amino Acid Sequence↗

PubMed1999

Cloning and expression of Shaker alpha- and beta-subunits during inner ear development.

Sensory cells of the chicken cochlea exhibit different ion channels relative to their position along the epithelium. One of these channels conducts an A-type potassium current which is found primarily in 'short' hair cells. Here, we report the first full length cloning and developmental expression of Shaker genes from this endorgan. Clones were obtained by screening a chicken (Gallus gallus) cochlea cDNA library, using probes made from RHK1 (i.e., Kvalpha1.4) cDNA, a Shaker homologue isolated from rat heart, and hKvbeta1.2 cDNA, a beta homologue isolated from human heart. Sequence analysis revealed a chick homologue of Kvalpha1.4, with a deduced amino acid similarity of 76-79% to mammalian Kvalpha1.4, and a chick homologue of Kvbeta1.1, with a similarity of 95% to mammalian Kvbeta1.1. In addition, we isolated a variant of cKvalpha1. 4 (cKvalpha1.4(m)) that differs in its untranslated regions and shows complete similarity in its coding region, except for the deletion of a single nucleotide. During development of the inner ear, reverse transcription-polymerase chain reaction (RT-PCR) studies show that the beta-subunit is expressed as early as embryonic day 3, whereas alpha- and beta-subunits are coexpressed on embryonic days 7 to 10, 14, and in adult.

Animals↗

PubMed1999

Enhancement of enzyme reaction of magnetically anisotropic polyacrylamide gel rods immobilized with ferromagnetic powder and beta-D-galactosidase in an alternating magnetic field.

An immobilized polyacrylamide gel containing beta-D-galactosidase and Sr-Ba-ferrite was magnetized in a static magnetic field. The gel rods (10 mm long, O 2 mm) exhibiting magnetic anisotropy could move at lower than 100 Hz but not at higher than 250 Hz in an alternating magnetic field of 200 Oe. In case of immovability of gel rods, the apparent enzymic activity increased 3 times higher under exposure of an alternating magnetic field of 500 Oe (570 Hz). It could be explained that the ferromagnetic powder inside the gel might vibrate under the influence of elasticity of gel in the alternating magnetic field of 100 or 500 Oe and 0.2-12 kHz. This might facilitate faster diffusion of the substance inside the gel and transportation of the substrate and the product through the surface of gel. Consequently, the enzyme reaction was apparently activated.

Acrylic Resins↗

PubMed1999

Functional properties of two bombesin-like peptide receptors revealed by the analysis of mice lacking neuromedin B receptor.

The neuromedin B-preferring receptor (NMB-R) is one of the members of the bombesin (BN)-like peptide receptor subfamily in mammals. Previously, we have generated and characterized mice with targeted disruption of the two other BN-like peptide receptors, bombesin receptor subtype-3 (BRS-3) and gastrin-releasing peptide-preferring receptor (GRP-R). Here we describe the generation and analysis of NMB-R-deficient mice to investigate how NMB-R differs from BRS-3 and GRP-R. Compensation for NMB-R deficiency by overexpression of GRP-R and/or BRS-3 was not detected. Although the hypothermic effect of NMB was reduced by 50% in NMB-R-deficient mice, the effect of GRP infusion was comparable to the wild-type mice. In contrast, fundic smooth muscle contraction on stimulation with NMB or GRP was normal in NMB-R-deficient mice. Administration of GRP but not NMB suppressed glucose intake in both normal and NMB-R-deficient mice. These results suggest that the NMB-R has an essential role in thermoregulation, but not for smooth muscle contraction of the fundus or for the suppression of feeding behavior. In addition, the behavioral phenotypes of GRP-R-deficient mice were not observed in NMB-R-deficient mice. These data show that the functions of NMB-R and GRP-R are distinct, with only partial overlap.

Animals↗

PubMed1999

High-level and effective production of human mannan-binding lectin (MBL) in Chinese hamster ovary (CHO) cells.

We have developed a high-expression system of recombinant human mannan-binding lectin (MBL) with CHO cells. Geneticin-resistant transformants harboring human MBL cDNA in the expression vector pNOW/CMV-A were screened by immunoblot analysis for secretion of recombinant MBL. Cloning and selection by both geneticin and methotrexate resulted in the production of recombinant MBL to a final concentration of 128.8 microg/ml in media after four days of culture. SDS-PAGE and gel-filtration analyses showed that recombinant MBL is characterized by two lower-order oligomeric structures (apparent molecular weights: 1150 kDa and 300 kDa) compared to native MBL (apparent molecular weight: 1300 kDa). The recombinant human MBL has both sugar-binding and complement activation activity and, like native MBL, can inhibit hemagglutination of influenza A virus. Lectin blots with recombinant MBL indicate that it can bind such microorganisms as HIV and influenza virus suggesting that it might inhibit their infection of hosts. This high-level expression of human MBL with the full range of biological activity will be useful for studies on the immunological role of MBL in humans.

Animals↗

PubMed1999

Liver fatty acid-binding protein is a new prognostic factor for hepatic resection of colorectal cancer metastases.

BACKGROUND AND OBJECTIVES: Liver fatty acid-binding protein (L-FABP) is reported as a biological marker for enterocytic differentiation. We evaluated the prognostic value of L-FABP expression for patients undergoing hepatic resection of colorectal cancer metastases. METHODS: The study group comprised 68 patients who underwent hepatic resection for colorectal cancer metastases between 1982 and 1996 at Niigata University Medical Hospital, Niigata, Japan. L-FABP expression was immunohistochemically studied in metastatic liver tumors and their primary colorectal cancers. The relationship between L-FABP expression and patient prognoses was statistically analyzed. RESULTS: L-FABP was positively stained in 56% (38/68) of liver metastases from colorectal cancers and in 56% (38/68) of their primary tumors. Of 68 cases, 54 (79%) showed similar immunohistochemical findings between primary and metastatic tumors. Patients with L-FABP-positive liver metastases showed better prognosis than patients with L-FABP-negative metastases (P = 0.046). L-FABP expression in primary colorectal cancers more significantly (P = 0.009) affected long-term survival after hepatic surgery. Multivariate analysis revealed that the prognostic effect of L-FABP expression in primary colorectal cancers was exerted independently and that its impact was larger than conventional pathological prognosticators. CONCLUSIONS: L-FABP expression is suitable for use as a new presurgical prognostic factor for patients undergoing hepatic surgery for colorectal cancer metastases.

Adult↗

PubMed1999

Acute exercise causes mitochondrial DNA deletion in rat skeletal muscle.

The present study was conducted to determine the effects of acute overload exercise on mitochondrial DNA and the structure of skeletal muscles. Rats were forced to run for 20 min until reaching complete exhaustion. We detected the large-scale deletion (7052 bp) of mitochondrial DNA by the nested polymerase chain reaction, and also observed mitochondrial ultrastructural changes in the soleus muscle.

Animals↗

PubMed1999

Millimeter-Wave Spectrum of Fluorodiacetylene (H&sbond;C&tbond;C&sbond;C&tbond;C&sbond;F).

The millimeter-wave spectrum of HCCCCF was observed in the ground state as well as in the low-lying vibrationally excited states nu7, nu8, nu9 and also associated nu8 + nu9, 2nu9, and 3nu9 states. The HCCCCF molecule was produced by a dc glow discharge in a flowing vapor of 2,3,4,5,6-pentafluorostyrene. The l-type doubling constants determined are in good agreement with the values predicted from the harmonic force field calculation. Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

Heat shock preconditioning on mitochondria during warm ischemia in rat livers.

BACKGROUND: The aim of this study was to investigate the effects of stress tolerance from heat shock preconditioning on changes in mitochondrial functions during ischemia-reperfusion injury of the liver. MATERIALS AND METHODS: Rats were divided into a heat shock group (group HS) and a control group (group C). In group HS, rats received heat shock pretreatment 48 h prior to ischemia-reperfusion. Heat shock pretreatment was performed in a water bath at 42 degrees C for 15 min under general anesthesia. In group C, the same treatment was done with the water bath at 37 degrees C instead of at 42 degrees C. A 30-min warm ischemia by cramping the hepatoduodinal ligament (Pringle's maneuver) followed by a 60-min reperfusion was administered to all rats. Changes in membrane potential of hepatic mitochondria (MPM); mitochondrial respiratory function before ischemia (n = 5), after ischemia (n = 10), and after reperfusion (n = 10); and ATP recovery after reperfusion were compared between the groups. RESULTS: After a 30-min ischemia, MPM in group C decreased significantly and did not recover even after reperfusion. On the other hand, MPM in group HS was maintained even after a 30-min ischemia and 60 min into reperfusion as well. The respiratory control ratio (RCR) of the mitochondria in group C decreased to as low as 5.06 +/- 0.72 after a 30-min ischemia, but in group HS, RCR was maintained near a normal level. The ATP level recovered significantly earlier in group HS than in group C after reperfusion. CONCLUSIONS: Heat shock preconditioning of the liver protected mitochondria from loss of membrane integrity during ischemia and contributed to their ability to produce energy-rich phosphates during reperfusion.

Adenosine Triphosphate↗

PubMed1999

Sigmoid colon cancer presenting as complete rectal prolapse: report of a case.

We describe herein the unusual case of a 76-year-old woman who was diagnosed as having sigmoid colon cancer after presenting with complete rectal prolapse. The rectal prolapse was considered to have been caused by constipation accelerated by the colon cancer. The relationship between colorectal cancer and rectal prolapse has not yet been clarified; however, this case report suggests that rectal prolapse can present as a symptom of colorectal cancer. Thus, patients with a sudden onset of rectal prolapse should be screened for colorectal cancer.

Aged↗

PubMed1999

New simple technique for hepatic parenchymal resection using a Cavitron Ultrasonic Surgical Aspirator and bipolar cautery equipped with a channel for water dripping.

We have developed a new technique to resect hepatic parenchyma without inflow occlusion by using the Cavitron Ultrasonic Surgical Aspirator (CUSA) and bipolar cautery with a saline irrigation system. The significance of this method in hepatectomy was analyzed in comparison with historical control of hepatectomy using Pringle's maneuver. An ordinary bipolar cautery was remodeled with an infusion line to bring saline droplets down the inner surface of one arm of the tweezers through an opening about 1.5 cm proximal to its tip. The optimal flow rate of saline was approximately one drop per second. The power of bipolar cautery was adjusted to 50 watts. When the tweezer blades were approximated to 1 or 2 mm, saline droplets were directed to the tip of tweezers and could be immediately evaporated. After sonicating parenchymal cells, the tissue of small branches of Glisson's tree or small tributaries of the hepatic vein were coagulated by bipolar cautery. The coagulated cords were then easily cut by scissors. The impact of this technique on ordinary liver resections was evaluated by analyzing the postoperative clinical course in relation to the hepatic functional reserve necessary for major hepatectomy, duration of hepatectomy, and intraoperative blood loss. Hepatic resection without vascular occlusion using this technique could decrease the morbidity in patients who have less hepatic functional reserve. It could also decrease intraoperative blood loss. This new technique effectively decreased the surgical load of the remnant liver during parenchymal resection by avoiding ischemic stress. Consequently it extends the safety limits of major hepatectomy.

Electrocoagulation↗

PubMed1999

Pulmonary alveolar proteinosis in infants.

UNLABELLED: We investigated the histological and molecular characteristics of pulmonary alveolar proteinosis (PAP) in two siblings (a brother and sister) who did not exhibit respiratory distress at birth but who each developed symptoms during infancy. Histological analysis of lung specimens showed positive staining for surfactant proteins in both patients. The polymerase chain reaction revealed expression of messenger RNA for surfactant protein B (SP-B) in the lung specimens. No defect in SP-B which is characteristic of the congenital form of PAP was observed. The concentration of surfactant protein A (SP-A) in bronchial alveolar lavage (BAL) fluid was elevated in patient 1 suggesting the BAL concentration of SP-A may be a clue to the diagnosis of this form of PAP. CONCLUSION: The accumulation of surfactant protein A in two siblings with an infantile form of pulmonary alveolar proteinosis could be a clue to the diagnosis.

Biopsy↗

PubMed1999

Colocutaneous fistula after percutaneous endoscopic gastrostomy in a remnant stomach.

An 82-year-old woman underwent percutaneous endoscopic gastrostomy (PEG) 5 years after partial gastrectomy for cancer. Four months after PEG insertion, a colocutaneous fistula was noted at exchange of the PEG tube. Colocutaneous fistula is a rare and major complication of PEG with 10 reported cases to date. In eight of the 11 reported cases, including this case, fistulas appeared late (>6 weeks) after PEG insertion. This complication may heal after removal of the PEG alone, if the fistula has formed completely; otherwise a surgical approach is necessary for the treatment. Since five of the 11 reported patients had previously undergone abdominal surgery, prior abdominal surgery may increase the risk of a colonic injury after PEG. Open surgical gastrostomy is a wiser option when performing gastrostomy in patients with prior abdominal surgery.

Aged↗

PubMed1999

Management of adrenal metastasis of hepatocellular carcinoma by asynchronous resection of bilateral adrenal glands.

We report on a 65-year-old man who received asynchronous bilateral adrenalectomy for adrenal metastasis of hepatocellular carcinoma. Fifteen months after curative resection of right hepatic lobe for hepatocellular carcinoma, a metastatic lesion of the left adrenal gland was detected and left adrenalectomy was performed. Ten months after the second operation, a metastatic lesion in the right adrenal gland, associated with tumor thrombus in the inferior vena cava, was revealed. Transcatheter arterial embolization of the arteries feeding the metastatic tumor was performed, but its effects were incomplete. As there was the tumor thrombus in the inferior vena cava and no other intrahepatic recurrence or extrahepatic metastasis was found, resection of the right adrenal gland with tumor thrombus, without the employment of veno-venous bypass, was performed, followed by postoperative hormonal supplementation. Changes in the patient's alpha-fetoprotein level were clinically useful for the detection of the metastatic lesions and the evaluation of therapeutic effects. Metastasis to adrenal gland from hepatocellular carcinoma should be actively managed, and the appropriate surgical treatment selected, if intrahepatic recurrence and/or other extrahepatic metastasis are controlled. To achieve higher curability and better outcome in patients with bilateral adrenal metastasis of hepatocellular carcinoma, bilateral total adrenalectomy is indicated, accompanied by effective postoperative hormonal supplementation.

Adrenal Gland Neoplasms↗