Biomedical subjects

M Ito

Publications and source records attributed to M Ito.

At least 559 records · Page 31Linked to original sources

PubMed2000

Two types of Bacillus subtilis tetA(L) deletion strains reveal the physiological importance of TetA(L) in K(+) acquisition as well as in Na(+), alkali, and tetracycline resistance.

The chromosomally encoded TetA(L) protein of Bacillus subtilis is a multifunctional tetracycline-metal/H(+) antiporter that also exhibits monovalent cation/H(+) antiport activity and a net K(+) uptake mode. In this study, B. subtilis mutant strains JC112 and JC112C were found to be representative of two phenotypic types of tetA(L) deletion strains that are generated in the same selection. Both strains exhibited increased sensitivity to low tetracycline concentrations as expected. The mutants also had significantly reduced ability to grow in media containing low concentrations of K(+), indicating that the net K(+) uptake mode is of physiological consequence; the deficit in JC112 was greater than in JC112C. JC112 also exhibited (i) greater impairment of Na(+)- or K(+)-dependent growth at pH 8.3 than JC112C and (ii) a greater degree of Co(+2) as well as Na(+) sensitivity. Studies were initiated to explore the possibility of two different patterns of compensatory changes in other ion-translocating transporters in these mutants. Increased expression of two loci has thus far been shown. Increased expression of czcD-trkA, a locus with a proposed involvement in K(+) uptake, occurred in both mutants. The increase was highest in the presence of Co(2+) and was higher in JC112 than in JC112C. Deletion of czcD-trkA resulted in diminished growth of the wild-type and both mutant strains at low [K(+)], supporting a significant role for this locus in K(+) uptake. Expression of yheL, which is a homologue of the Na(+)/H(+) antiporter-encoding nhaC gene from Bacillus firmus OF4, was also increased in both tetA(L) deletion strains, again with higher up-regulation in JC112. The phenotypes resulting from deletion of yheL were consistent with a modest role for YheL in Na(+)-dependent pH homeostasis in the wild type. No major role for YheL was indicated in the mutants in spite of the overexpression. The studies underscore the multiple physiological functions of TetA(L), including tetracycline, Na(+), and alkali resistance and K(+) acquisition. The studies also reveal and begin to detail the complexity of the response to mutational loss of these functions.

Alkalies↗

PubMed2000

Retrospective diagnosis of diphtheria by detection of the Corynebacterium diphtheriae tox gene in a formaldehyde-fixed throat swab using PCR and sequencing analysis.

The tox gene of Corynebacterium diphtheriae was detected in a formaldehyde-fixed throat swab taken from a 68-year-old man who was reported to have died of suffocation due to a pharyngeal tumor. DNA templates prepared from bacterial cells fixed with 10% formaldehyde were subjected to a PCR analysis with tox gene-specific PCR primers. The resultant 112-nucleotide-long PCR product was sequenced using a dye terminator method, and an expected 57-nucleotide-long internal sequence of the tox gene was detected. This method is applicable for retrospective diagnosis in diphtheria cases in which only a formaldehyde-fixed clinical sample is available.

Base Sequence↗

PubMed2000

The interaction between the Drosophila secreted protein argos and the epidermal growth factor receptor inhibits dimerization of the receptor and binding of secreted spitz to the receptor.

Drosophila Argos (Aos), a secreted protein with an epidermal growth factor (EGF)-like domain, has been shown to inhibit the activation of the Drosophila EGF receptor (DER). However, it has not been determined whether Aos binds directly to DER or whether regulation of the DER activation occurs through some other mechanism. Using DER-expressing cells (DER/S2) and a recombinant DER extracellular domain-Fc fusion protein (DER-Fc), we have shown that Aos binds directly to the extracellular domain of DER with its carboxyl-terminal region, including the EGF-like domain. Furthermore, Aos can block the binding of secreted Spitz (sSpi), a transforming growth factor alpha-like ligand of DER, to the extracellular domain of DER. We observed that sSpi stimulates the dimerization of both the soluble DER extracellular domain (sDER) and the intact DER in the DER/S2 cells and that Aos can block the sSpi-induced dimerization of both sDER and intact DER. Moreover, we have shown that, by directly interacting with DER, Aos and SpiAos (a chimeric protein that is composed of the N-terminal region of Spi and the C-terminal region of Aos) inhibit the dimerization and phosphorylation of DER that are induced by DER's overexpression in the absence of sSpi. These results indicate that Aos exerts its inhibitory function through dual molecular mechanisms: by blocking both the receptor dimerization and the binding of activating ligand to the receptor. This is the first description of this novel inhibitory mechanism for receptor tyrosine kinases.

Animals↗

PubMed2000

Percutaneous in vivo gene transfer to the peripheral lungs using plasmid-liposome complexes.

The purpose of this study was to investigate a new method of in vivo gene transfer to the lung parenchyma by the percutaneous approach. The plasmid that contains the gene for firefly luciferase driven by a cytomegalovirus (CMV) promoter (pCMVL) in combination with cationic lipids was percutaneously injected into the lung parenchyma. Luciferase activities were localized to the lobes of the lung where the plasmids with cationic lipids were injected. Percutaneous injection of the plasmid containing the human endothelin-1 (hET-1) gene driven by a CMV promoter (pRc/CMVhET-1) in combination with cationic lipids into the lungs caused pulmonary fibrosis localized to the injection site in the peripheral lungs. We concluded that percutaneous in vivo gene transfer to the lungs is a unique and important approach to introduce exogenous gene expression in the limited area of the lung parenchyma. This method of gene transfer will be applicable for human gene therapy for targeted areas of peripheral lung and will also be useful to assess the function of the proteins expressed by a gene in the local area of the lungs.

Adenocarcinoma↗

PubMed2000

In vivo estimation of contraction velocity of human vastus lateralis muscle during "isokinetic" action.

To determine the shortening velocities of fascicles of the vastus lateralis muscle (VL) during isokinetic knee extension, six male subjects were requested to extend the knee with maximal effort at angular velocities of 30 and 150 degrees /s. By using an ultrasonic apparatus, longitudinal images of the VL were produced every 30 ms during knee extension, and the fascicle length and angle of pennation were obtained from these images. The shortening fascicle length with extension of the knee (from 98 to 13 degrees of knee angle; full extension = 0 degrees ) was greater (43 mm) at 30 degrees /s than at 150 degrees /s (35 mm). Even when the angular velocity remained constant during the isokinetic range of motion, the fascicle velocity was found to change from 39 to 77 mm/s at 150 degrees /s and from 6 to 19 mm/s at 30 degrees /s. The force exerted by a fascicle changed with the length of the fascicle at changing angular velocities. The peak values of fascicle force and velocity were observed at approximately 90 mm of fascicle length. In conclusion, even if the angular velocity of knee extension is kept constant, the shortening velocity of a fascicle is dependent on the force applied to the muscle-tendon complex, and the phenomenon is considered to be caused mainly by the elongation of the elastic element (tendinous tissue).

Adult↗

PubMed2000

Analysis of urgent colonoscopy for lower gastrointestinal tract bleeding.

BACKGROUND: Three hundred and forty-five patients who underwent urgent colonoscopy for acute hematochezia during the past 20 years (from 1976 to 1995) were retrospectively analyzed. METHODS: Urgent colonoscopy was defined as endoscopy performed within 24 h after a bleeding episode. Preparation was initially minimal with a water or glycerine enema. Recently, however, polyethylene glycol is used. RESULTS: The overall diagnostic accuracy for bleeding site detection was 89.1% (307 cases). Successful insertion was made to the ileocecal region in 193 cases (55.9%). The disease most frequently discoverd by urgent colonoscopy was transient ischemic colitis (62 cases). Negative urgent colonoscopy specimens (18 cases) were later diagnosed by other methods as being small intestinal bleeding foci. In 10 cases, initial colonoscopy failed to detect the bleeding foci. Endoscopic hemostasis was performed in 48 cases. Permanent hemostasis succeeded in 32 cases (66.7%). Complications of urgent colonoscopy were fever after the examination (22 cases) and hypotension during endoscopy (7 cases). CONCLUSION: Urgent colonoscopy is considered to be a safe and useful examination for acute lower gastrointestinal bleeding and hemostasis.

Acute Disease↗

PubMed2000

Correlation between progesterone binding sites on human spermatozoa and in vitro fertilization outcome.

We investigated whether the expression of progesterone-binding sites on human sperm acrozomal membrane is correlated with in vitro fertilization outcome. In motile sperm we evaluated percentage of progesterone-binding sperm (%PB) and of acrozome-reacted sperm (%AR), collected from 39 male partners undergoing an in vitro fertilization program (IVF), by labeling the sperm with progesterone-conjugated BSA-labeled FITC (P-BSA-FITC) and pisum sativum agglutinin labeled-FITC (PSA-FITC). Mean %PB in 30 fertilized cases was significantly higher than that in 9 fertilization failures (9.0 +/- 5.1 vs. 22.3 +/- 14.8%, p < 0.01). Furthermore, %PB shows a strong positive correlation with fertilization rate in IVF (r = 0.44) and %AR (r = 0.62), but not with sperm concentration and sperm motility. These results suggest that the expression of progesterone receptor on the sperm was related to the sperm fertilizability, and the evaluation of %PB was useful for predicting the fertilization outcome of IVF.

Cell Membrane↗

PubMed2000

Nitric oxide affects angiotensin II pressor response: possible mechanism of attenuated pressor response during pregnancy and etiology of pregnancy-induced hypertension.

OBJECTIVE: To investigate the mechanism of attenuated pressor responses to several vasoconstrictors during gestation, we sought to characterize the effects of N(G)-monomethyl-L-arginine (L-NMMA) and L-arginine (L-Arg) on the pressor response to the infusion of angiotensin II in rats. METHODS: L-NMMA and L-Arg were infused intraperitoneally into rats at a constant rate by means of an osmotic minipump. The L-NMMA group received an infusion of L-NMMA (3 mg/day) daily for 13 days, whereas the L-NMMA plus L-Arg group received L-NMMA (3 mg/day) daily for 4 days, followed by L-NMMA plus L-Arg (12 mg/day) daily for 9 days. Sham-operated rats served as controls. The animals were anesthetized on day 13, and catheters were placed into the femoral artery and vein. After the animals had recovered from anesthesia, the pressor response to intravenous bolus doses of angiotensin II (50, 100, 200, and 400 ng/kg) were determined after recovery from anesthesia. RESULTS: While the baseline mean arterial blood pressure was not affected by L-NMMA, with or without L-Arg, the pressor response to angiotensin II in the L-NMMA group was significantly increased as compared with that in the control group, at doses of 50, 100, and 200 ng/kg. The response of the L-NMMA plus L-Arg group did not differ significantly from that of the control group. CONCLUSION: Results indicate that the infusion of a nitric oxide synthase inhibitor, at a dose insufficient to produce hypertension, increases the pressor response to angiotensin II.

Angiotensin II↗

PubMed2000

Urinary orotic acid levels in normal pregnancy and pregnancy-induced hypertension.

Our objective was to study the urinary levels of orotic acid in normal pregnancy and in pregnancy-induced hypertension. Such levels were measured using high-performance liquid chromatography with column-switching. The levels of urinary orotic acid (micromol/g creatinine) in normal pregnancy (n = 14) were 6.9 +/- 2.3 (first trimester), 10.1 +/- 2.4 (20 weeks) and 12.0 +/- 3.7 (30 weeks). In pregnancy-induced hypertension (n = 14), the corresponding levels were 6.5 +/- 1.7, 7.8 +/- 2.7 and 7.6 +/- 2.3, respectively. Normal pregnant subjects individually showed a significant elevation at 20 and 30 weeks of gestation as compared with those in the first trimester (p < 0.01). A high consumption of arginine in nitric oxide production during normal pregnancy may cause a physiological elevation of urinary orotic acid. The absence of an elevation in pregnancy-induced hypertension may be associated with a decrease in nitric oxide production.

Arginine↗

PubMed2000

Coasting may reduce the severity of the ovarian hyperstimulation syndrome in patients with polycystic ovary syndrome.

The aim of our study was to determine the efficacy of postponing administration of human chorionic gonadotropin while continuing daily gonadotropin-releasing hormone agonist therapy ('coasting') to prevent the occurrence of severe ovarian hyperstimulation syndrome (OHSS) for patients with polycystic ovary (PCO) syndrome. Five patients with PCO who had been hospitalized due to severe OHSS in previous in vitro fertilization and embryo transfer or intrauterine insemination cycles at the Tottori University Hospital were included in the study. The rates of mature oocytes and fertilization were comparable between the cycles. A singleton pregnancy was achieved in a patient during the coasting cycle, and none of the women developed severe OHSS in coasting cycles. The results suggest that coasting may be an alternative method for reducing the severity of OHSS in patients with PCO.

Adult↗

PubMed2000

Athymic nude rats develop severe pulmonary hypertension following monocrotaline administration.

OBJECTIVE: To investigate the significance of the presence or absence of the thymus in the development of pulmonary hypertension (PH) following monocrotaline (MCT) administration, the degree of MCT-induced PH (MCT-PH) in athymic nude (F344/N Jcl-rnu) rats was compared with that in their euthymic (rnu/+) littermates. METHODS: Histopathological studies of the lung in terms of interstitial edema, congestion, thickening of the alveolar wall, inflammatory cell infiltration and degeneration of arteries were performed by staining with hematoxylin-eosin (HE), elastin van Gieson and Masson's trichrome. The medial wall thickness of the small pulmonary arteries and the weight ratio of the right ventricular free wall (RV) to that of the left ventricle plus septum [RV/(LV + S) weight ratio] were used as indices of the degree of PH. Toluidine blue staining was performed to estimate the number of the mast cells in the lung interstitium. RESULTS: Interstitial edema was significantly severer in MCT- injected euthymic rats than in MCT-injected athymic nude rats (p < 0.01); in contrast, the thickening of the alveolar wall was severer in MCT-injected athymic nude rats than in MCT-injected euthymic rats (p < 0.05). The degree of MCT-PH, as determined by the medial wall thickness of the small pulmonary arteries and RV/(LV + S) weight ratio in MCT-injected athymic nude rats, was significantly severer than in MCT-injected euthymic rats (p < 0.05 and p < 0.01, respectively). The number of mast cells was significantly greater in MCT-injected athymic nude rats than in MCT-injected euthymic rats (p < 0.01). The degree of the medial wall thickness of the small pulmonary arteries was significantly correlated with RV/(LV + S) weight ratio (p < 0.05) as well as with the number of mast cells in MCT-injected rats. CONCLUSIONS: Athymic nude rats developed severer PH than euthymic rats along with a greater number of mast cells and severer histopathological changes, such as thickening of the alveolar wall. Mast cell proliferation was considered to play a pivotal role in the development of PH in MCT-PH.

Animals↗

PubMed2000

Regulation of CD69 expression on eosinophil precursors by interferon-gamma.

The purpose of this study was to determine whether interferon-gamma (IFN-gamma) induced CD69 expression by eosinophil precursors. Eosinophil precursors were induced from CD34+ cord blood cells using recombinant human interleukin-3 (IL-3) and interleukin-5 (IL-5). On day 14 of culture, cells constitutively expressed CD69 and the IFN-gamma receptor (IFN-gammaR). Stimulation with IFN-gamma for 24 h did not affect IFN-gammaR expression by the cells. On the other hand, IFN-gamma significantly upregulated CD69 expression by the precursors after 24 h of incubation. A specific JAK2 inhibitor (AG-490) caused a concentration-dependent suppression of IFN-gamma-induced CD69 expression by the precursors. In conclusion, these results indicate that IFN-gamma induces CD69 expression by eosinophil precursors via the activation of JAK2.

Antigens, CD↗

PubMed2000

Arteriovenous malformation of the medulla oblongata supplied by the anterior spinal artery in a child: treatment by microsurgical obliteration of the feeding artery.

We report a unique case of a 3-year-old boy with a pial arteriovenous malformation (AVM) in the medulla. The patient presented with a subarachnoid hemorrhage. Magnetic resonance (MR) imaging revealed a 3 x 1 cm flow void area in the premedullary cistern that was compressing the medulla posteriorly. Cerebral angiography and MR angiography showed an aneurysm-like vascular pouch that was fed by the anterior spinal artery and had multiple draining veins. The case was diagnosed as a fistula-type AVM. Treatment options consisted of endovascular embolization or open surgery. We used a left far lateral approach to obliterate the anterior spinal artery. Immediately after the clip was applied to the feeding artery, the pouch began to shrink, and the color of the draining veins changed from red to blue. An intraoperative angiography showed that the AVM had disappeared. The patient recovered fully 1 month after surgery. This case was classified as fistula-type AVM, pial arteriovenous fistula (AVF). Microsurgical obliteration of the anterior spinal artery is considered to be the treatment of choice for perimedullary AVF located in the premedullary cistern if the endovascular treatment is not considered to be feasible.

Arteries↗

PubMed2000

Complete antithrombin deficiency in mice results in embryonic lethality.

Antithrombin is a plasma protease inhibitor that inhibits thrombin and contributes to the maintenance of blood fluidity. Using targeted gene disruption, we investigated the role of antithrombin in embryogenesis. Mating mice heterozygous for antithrombin gene (ATIII) disruption, ATIII(+/-), yielded the expected Mendelian distribution of genotypes until 14.5 gestational days (gd). However, approximately 70% of the ATIII(-/-) embryos at 15.5 gd and 100% at 16.5 gd had died and showed extensive subcutaneous hemorrhage. Histological examination of those embryos revealed extensive fibrin(ogen) deposition in the myocardium and liver, but not in the brain or lung. Furthermore, no apparent fibrin(ogen) deposition was detected in the extensive hemorrhagic region, suggesting that fibrinogen might be decreased due to consumptive coagulopathy and/or liver dysfunction. These findings suggest that antithrombin is essential for embryonic survival and that it plays an important role in regulation of blood coagulation in the myocardium and liver.

Animals↗

PubMed2000

A novel mutation in DAX1 causes delayed-onset adrenal insufficiency and incomplete hypogonadotropic hypogonadism.

Mutations in the DAX1 gene cause X-linked adrenal hypoplasia congenita (AHC) and hypogonadotropic hypogonadism (HHG). In affected boys, primary adrenal insufficiency occurs soon after birth or during early childhood; HHG is recognized at the expected time of puberty. In this report, we describe the novel phenotype of a man who presented with apparently isolated adrenal insufficiency at 28 years of age. Examination revealed partial pubertal development and undiagnosed incomplete HHG. Gonadotropin therapy did not improve his marked oligospermia, suggesting a concomitant primary testicular abnormality. Genomic analysis revealed a novel missense mutation, I439S, in DAX1. The mutant DAX-1 protein was studied for its ability to function as a transcriptional repressor of target genes. Consistent with the patient's mild clinical phenotype, the I439S mutation conferred intermediate levels of repressor activity of DAX-1 when compared with mutations associated with classic AHC. This unique case extends the clinical spectrum of AHC to include delayed-onset primary adrenal insufficiency in adulthood and milder forms of HHG. Furthermore, in accordance with findings in Ahch (Dax1) knockout mice, the clinical features in this patient suggest that DAX-1 function is required for spermatogenesis in humans, independent of its known effects on gonadotropin production.

Adrenal Glands↗

PubMed2000

Expansion of human NOD/SCID-repopulating cells by stem cell factor, Flk2/Flt3 ligand, thrombopoietin, IL-6, and soluble IL-6 receptor.

Here, we demonstrate a significant ex vivo expansion of human hematopoietic stem cells capable of repopulating in NOD/SCID mice. Using a combination of stem cell factor (SCF), Flk2/Flt3 ligand (FL), thrombopoietin (TPO), and a complex of IL-6 and soluble IL-6 receptor (IL-6/sIL-6R), we cultured cord blood CD34(+) cells for 7 days and transplanted these cells into NOD/SCID mice. Bone marrow engraftment was judged successful when recipient animals contained measurable numbers of human CD45(+) cells 10-12 weeks after transplantation. When cells were cultured with SCF+FL+TPO+IL-6/sIL-6R, 13 of 16 recipients were successfully engrafted, and CD45(+) cells represented 11.5% of bone marrow cells in engrafted recipients. Cells cultured with a subset of these factors were less efficiently engrafted, both as measured by frequency of successful transplantations and prevalence of CD45(+) cells. In animals receiving cells cultured with all 4 factors, human CD45(+) cells represented various lineages, including a large number of CD34(+) cells. The proportion of CD45(+) cells in recipient marrow was 10 times higher in animals receiving these cultured cells than in those receiving comparable numbers of fresh CD34(+) cells, and the expansion rate was estimated at 4.2-fold by a limiting dilution method. Addition of IL-3 to the cytokine combination abrogated the repopulating ability of the expanded cells. The present study may provide a novel culture method for the expansion of human transplantable hematopoietic stem cells suitable for clinical applications.

Animals↗

PubMed2000

Disruption of the fibroblast growth factor-2 gene results in decreased bone mass and bone formation.

Basic fibroblast growth factor (FGF-2), an important modulator of cartilage and bone growth and differentiation, is expressed and regulated in osteoblastic cells. To investigate the role of FGF-2 in bone, we examined mice with a disruption of the Fgf2 gene. Measurement of trabecular bone architecture of the femoral metaphysis of Fgf2(+/+) and Fgf2(-/-) adult mice by micro-CT revealed that the platelike trabecular structures were markedly reduced and many of the connecting rods of trabecular bone were lost in the Fgf2(-/-) mice. Dynamic histomorphometry confirmed a significant decrease in trabecular bone volume, mineral apposition, and bone formation rates. In addition, there was a profound decreased mineralization of bone marrow stromal cultures from Fgf2(-/-) mice. This study provides strong evidence that FGF-2 helps determine bone mass as well as bone formation.

Alkaline Phosphatase↗

PubMed2000

Current therapy for West syndrome in Japan.

We sent questionnaires concerning the current therapy for West syndrome to 208 institutions at which pediatric care members of the Japan Epilepsy Society were working. Of these, 129 (62%) institutions responded. Vitamin B6 was the preferred first-line drug, followed by the combination of vitamin B6 and valproate or monotherapy with valproate. Corticotropin was the third choice among the drugs. The dosage of corticotropin was lower than previously reported. The treatment of West syndrome is not well established at present and further research is needed to improve the therapeutic protocol.

Adrenocorticotropic Hormone↗