Search PubMed⌕ Search

Biomedical subjects

M Naito

Publications and source records attributed to M Naito.

At least 163 records · Page 9Linked to original sources
PubMed1999

Evaluation of the pancreas: a comparison of single thick-slice MR cholangiopancreatography with multiple thin-slice volume reconstruction MR cholangiopancreatography.

OBJECTIVE: The purpose of this study was to assess abilities of single thick-slice MR cholangiopancreatography and multiple thin-slice multiprojection volume reconstruction (MPVR) MR cholangiopancreatography to evaluate diseases in and around the pancreas. SUBJECTS AND METHODS: Eighty-nine patients underwent both single and MPVR MR cholangiopancreatography using a single-shot fast spin-echo technique. Image quality (five-point scale), visualization of the common bile and pancreatic ducts (three-point scale), stenotic, dilatational, or cystic changes of the pancreatic ducts, and other pathologic findings were evaluated. RESULTS: Image quality was high for single and MPVR MR cholangiopancreatography (4.1+/-0.7 and 4.5+/-0.6, respectively). Misregistration was noted in 19 patients with MPVR MR cholangiopancreatography. Ducts on and around the greater duodenal papilla and the common bile duct were revealed better using MPVR than single MR cholangiopancreatography (p < .05). Overall sensitivity, specificity, and accuracy for detection of stenosis of the main pancreatic ducts were 83.3%, 93.6%, and 88.8%, respectively, using single MR cholangiopancreatography and 76.2%, 97.9%, 87.6%, respectively, using MPVR MR cholangiopancreatography. Dilatation of the pancreatic ducts (100%) and cystic changes (n = 17 and n = 19, respectively) were well seen using either single or MPVR MR cholangiopancreatography. Although stenotic changes of the nondilated main pancreatic ducts and their branches were difficult to evaluate using single (62.5% and 14.3%, respectively) or MPVR (43.8% and 21.4%, respectively) MR cholangiopancreatography, single MR cholangiopancreatography better depicted ductal continuity. CONCLUSION: For evaluation of the pancreas, single and MPVR MR cholangiopancreatography provide complementary data; thus, we recommend using a combination of these two MR cholangiopancreatography techniques.

Adult↗
PubMed1999

In vivo and in vitro evidence of blood-brain barrier transport of a novel cationic arginine-vasopressin fragment 4-9 analog.

The blood-brain barrier (BBB) transport and metabolism of a novel arginine-vasopressin fragment 4-9 [AVP(4-9), isoelectric point; (pI) = 9.2] analog, that is, cationic AVP(4-9) (C-AVP(4-9), PI = 9.8), were examined in vivo and in vitro. At 45 min after an i.v. administration to mice, the cerebrum-to-plasma concentration ratios of (35)S-labeled AVP(4-9) and (125)I-labeled C-AVP(4-9) were 0.103 and 0.330 ml/g cerebrum, respectively, and the BBB permeation clearances were 1.47 x 10(-4) and 3.10 x 10(-4) ml/min/g cerebrum, respectively. In the in vitro study using mouse brain capillary endothelial cells immortalized by SV40 infection (MBEC4), the acid-resistant binding values of (35)S-labeled AVP(4-9) and (125)I-labeled C-AVP(4-9) to MBEC4 at 120 min were 0.93 and 1.95 microliter/mg protein (as the cell/medium ratios), respectively. (35)S-labeled AVP(4-9) showed two-phase saturable acid-resistant binding, and its half-saturation constants (K(D)) were 3.8 nM (high affinity) and 45.7 microM (low affinity). (125)I-labeled C-AVP(4-9) showed single-phase saturable acid-resistant binding, with a K(D) value of 16.4 microM. The acid-resistant binding of (125)I-labeled C-AVP(4-9) was significantly dependent on temperature and medium osmolarity. The acid-resistant binding of (125)I-labeled C-AVP(4-9) was inhibited by dancylcadaverine, phenylarsine oxide (endocytosis inhibitors), 2,4-dinitrophenol (a metabolic inhibitor), and AVP(4-9), poly(L-lysine), and protamine (cationic substances), but not by poly(L-glutamic acid) (an anionic peptide) and the V(1) and V(2) vasopressin receptor antagonists. In addition, the conversion of C-AVP(4-9) to AVP(4-9) in the cerebral homogenate was confirmed by HPLC and mass spectrometry. The present results demonstrate that C-AVP(4-9) is transported through the BBB more effectively than AVP(4-9), via absorptive-mediated endocytosis, and that C-AVP(4-9) is converted to the neuroactive parent peptide, AVP(4-9), in the cerebrum.

Animals↗
PubMed1999

Transtrochanteric curved varus femoral osteotomy for spondyloepiphyseal dysplasia tarda. A case report.

A female with spondyloepiphyseal dysplasia (SED) tarda suffered bilateral hip pain since about the age of ten. Her radiographs revealed subluxation and irregularity of the hip joints with acetabular dysplasia. Transtrochanteric varus osteotomy was performed on her left femur at 13 years of age and on her right femur at 14 years of age. The congruities of both hips improved after surgery. At follow-up, she had no pain in either hip even after walking for an extended period. Improved activity in daily life was noted.

Adolescent↗
PubMed1999

Fibrin gel induces the migration of smooth muscle cells from rabbit aortic explants.

A major step in the pathogenesis of atherosclerosis is the vectorial migration of smooth muscle cells (SMCs) from the arterial media into the intima. Although subcultured SMCs usually show synthetic phenotype, the behaviour of contractile SMCs may be crucial for the subsequent migration of the cells. In the present study, we utilized an in vitro assay system to evaluate the effects of fibrin gels on the migration of SMCs from explants taken from rabbit aorta. After cultured for 5-7 days in a serum-free condition, SMCs appeared from explants covered with fibrin gel. The cells were positive on immunostaining for SMC specific alpha-actin. No migration of SMCs from the control explants without fibrin gel was observed. Then the percentage of explants showing cell migration and the number of migrating cells increased with time. The migration of SMCs into fibrin gels was not dependent on the concentration of fibrinogen used for the preparation of fibrin gel in the range of 1.5-3 mg/ml. Variations of thrombin concentration in the range of 0.25-1.25 U/ml had no significant effect. However, there was less migration of SMCs with higher concentrations of thrombin. Thrombin inhibitors, hirudin and PPACK had no significant effect on the migration of SMCs. An RGD-containing peptide, GRGDS inhibited the migration of SMCs although a control peptide GRGES at the same concentration had no significant effect. A monoclonal antibody to alphavbeta3, LM609, completely inhibited the migration of SMCs from the explants, suggesting that alphavbeta3 integrin is involved in the migration of SMCs into fibrin gels. SMCs which migrated from the explants showed the positive staining with the monoclonal antibodies against SMC myosin heavy chain isoforms, SMemb, SM1 and SM2, suggesting that they are in an intermediate state changing from contractile to synthetic state. In conclusion, the present study showed that fibrin gel induces the migration of SMCs from explants into itself and the process may not need other growth factors or cytokines.

Animals↗
PubMed1999

[A clinicobacteriologic study on clavulanic acid/amoxicillin in pediatric acute otitis media].

We carried out clinical and bacteriological studies on clavulanic acid/amoxicillin and amoxicillin in pediatric acute otitis media at 14 general practice settings. The results are summarized as follows. 1. The major isolated organisms from content of middle ear effusion were Streptococcus pneumoniae 31.8%, Haemophilus influenzae 35.8% and Moraxella subgenus Branhamella catarrhalis 1.5%. Similar results were observed for the major isolates organisms from content of nasopharynx Streptococcus pneumoniae 31.1%, Haemophilus influenzae 33.9% and Moraxella subgenus Branhamella catarrhalis 19.2%. 2. 42.2% of S. pneumoniae isolated from middle ear effusion were drug resistant S. pneumoniae (PISP, PRSP) and they were increasing year by year. 3. 46.7% of S. pneumoniae isolated from nasopharyngeal swab were drug resistant S. pneumoniae (PISP, PRSP) and they were increasing year by year. The incidence of drug resistant S. pneumoniae isolated from all cases and organisms were 26.3% and 14.5%, respectively. 4. On MIC90, antimicrobial activity of CVA/AMPC against Streptococcus pneumoniae, Haemophilus influenzae and Moraxella subgenus Branhamella catarrhalis was superior to SBTPC. 5. In the evaluation of clinical efficacy, bacteriological efficacy and utility, CVA/AMPC-treated group was significantly superior to AMPC-treated group. 6. Adverse reactions were observed in 22% of CVA/AMPC-treated group, involving diarrhea and loose stool.

Acute Disease↗
PubMed1999

[A clinicobacteriologic study on clavulanic acid/amoxicillin in pediatric sinusitis].

We carried out clinical and bacteriological studies on clavulanic acid/amoxicillin and amoxicillin in pediatric sinusitis at 11 general practice settings. The results are summarized as follows. 1. The major isolated organisms from content of middle meatus were Streptococcus pneumoniae 32.2%, Haemophilus influenzae 32.0% and Moraxella subgenus Branhamella catarrhalis 25.1%. Similar results were observed for the major isolates from nasopharynx. 2. 62.1% of S. pneumoniae isolated were drug resistant S. pneumoniae (PISP, PRSP) and they were increasing year by year. 3. Drug resistant S. pneumoniae was isolated from 38.6% of all cases. 4. Regarding MIC90, CVA/AMPC showed superior antimicrobial activity against Streptococcus pneumoniae, Haemophilus influenzae and Moraxella subgenus Branhamella catarrhalis. 5. The clinical efficacy, bacteriological efficacy and utility of CVA/AMPC-treated group were 78%, 58% and 72.8%, respectively, and they were significantly superior to AMPC-treated group. 6. Adverse reactions were observed in 11.2% of CVA/AMPC group, involving diarrhea and stool loose and there was no statistical deference from those of AMPC group.

Amoxicillin↗
PubMed1999

High-affinity efflux transport system for glutathione conjugates on the luminal membrane of a mouse brain capillary endothelial cell line (MBEC4).

Cumulative evidence suggests that several organic anions are excreted from the brain to the blood across the blood-brain barrier. In the present study, we carried out a kinetic investigation of the transport activity in MBEC4, an immortalized cell line established from BALB/c mouse cerebral microvessel endothelial cells. The presence of an efflux system in intact cells was examined by using monochlorobimane (MCB), which is conjugated with glutathione intracellularly to produce glutathione bimane (GS-B). The efflux of GS-B was inhibited by ATP depletion and also by 1-chloro-2, 4-dinitrobenzne, a precursor of 2,4-dinitrophenyl-S-glutathione, in a concentration-dependent manner. Using this MBEC4 monolayer, we investigated the direction of this transport activity. Although the efflux of GS-B was observed on both luminal and abluminal sides of MBEC4 monolayer, the profile differed for the two sides with respect to the concentration dependence of MCB; the analysis suggested the presence of high-affinity transport system on the luminal side. To investigate the mechanism for the transport, we examined the ATP-dependent uptake of GS-B into the membrane vesicles prepared from MBEC4. ATP-dependent uptake systems with high (Km = 35 nM) and low (Km = 14 microM) affinities were identified. These results suggested that this high-affinity transport system of glutathione conjugates is expressed on the luminal side of the blood-brain barrier and is involved in the detoxification of xenobiotics.

Animals↗
PubMed1998

Bifurcated dendritic cell differentiation in vitro from murine lineage phenotype-negative c-kit+ bone marrow hematopoietic progenitor cells.

We have recently established the culture system to generate dendritic cells (DCs) from murine Lin-c-kit+ bone marrow hematopoietic progenitor cells (HPCs) in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) + stem cell factor (SCF) + tumor necrosis factor-alpha (TNF-alpha). We present here the identification of two DC precursor subsets originated from HPCs with the phenotype of CD11b-/dullCD11c+ and CD11b+hiCD11c+ that develop independently at early time points (days 4 to 6) in the same culture conditions. Both of CD11b-/dullCD11c+ and CD11b+hiCD11c+ precursors could differentiate at day 10 to 14 into CD11b-/dullCD11c+ mature DCs with typical morphology, phenotype, and the ability to stimulate allogenic mixed leukocyte reaction (MLR). However, the endocytic capacity of fluorescein isothiocyanate-dextran was markedly reduced during the differentiation. CD11b-/dullCD11c+ precursors expressed high levels of Ia, CD86, CD40, and E-cadherin molecules, but not c-fms transcript, and mature DCs derived from this precursor subset continue to express abundant E-cadherin antigen, a discernible marker for Langerhans cells. In contrast, CD11b+hiCD11c+ precursors expressed c-fms mRNA, but low levels of Ia, CD86, and E-cadherin, whereas CD40 was undetectable. CD11b-/dullCD11c+ mature DCs differentiated from these precursors displayed abundant c-fms mRNA and nonspecific esterase activity. Interestingly, CD11b+hiCD11c+ precursors, but not CD11b-/dullCD11c+ precursors, may be bipotent cells that can be induced by M-CSF to differentiate into macrophages. All of these results suggest that CD11b-/dullCD11c+ and CD11b+hiCD11c+ cells are distinct DC precursors derived from Lin-c-kit+ HPCs, which differentiate into mature DCs through bifurcated and independent DC differentiation pathways.

Animals↗
PubMed1998

Physiologic regulation of postovulatory neutrophil migration into vagina in mice by a C-X-C chemokine(s).

Leukocytes, particularly neutrophils, infiltrate into female genital organs after ovulation in both humans and mice. In mice, a female sexual cycle consists of 5 phases: proestrus, estrus, metestrus-1, metestrus-2, and diestrus. Ovulation occurs at estrus; at metestrus-2, a large number of neutrophils infiltrate into the vaginal epithelium accompanied by an increased neutrophil number in vaginal lavage fluid. Concomitantly, concentrations of a functional IL-8 homologue, murine macrophage inflammatory protein (MIP)-2, were increased significantly in vaginal lavage fluid at metestrus-2 as compared with other phases. On the contrary, MIP-2 was not detected in plasma during the whole course of a sexual cycle. Moreover, immunohistochemical analyses demonstrated that MIP-2 protein expression was prominent at the upper layer of the vaginal epithelium at metestrus-2, in contrast to a marginal staining in the vaginal epithelium at proestrus and estrus. These results suggest that a C-X-C chemokine, MIP-2, was produced physiologically in the vaginal epithelium in a sexual cycle-dependent manner. Furthermore, the administration of neutralizing anti-IL-8R homologue Abs at proestrus abrogated leukocyte infiltration into the vagina at metestrus. However, anti-MIP-2 Abs reduced leukocyte influx at metestrus by approximately 50%. Thus, a murine IL-8 homologue, MIP-2, and its related molecules physiologically regulate neutrophil migration into the vagina in a sexual cycle-dependent manner.

Animals↗
PubMed1998

Effect of crosslinking by factor XIIIa on the migration of vascular smooth muscle cells into fibrin gels.

We evaluated the migration of vascular smooth muscle cells into crosslinked fibrin gels, using an in vitro assay system. Vascular smooth muscle cells from bovine fetal aorta migrated into non-crosslinked and crosslinked fibrin gels and showed a characteristic elongated spindle-shaped appearance with long cytoplasmic processes. The cells displayed two-fold increase in migration into crosslinked fibrin gels compared to non-crosslinked gels, suggesting the importance of fibrin crosslinking by factor XIIIa on its three-dimensional structure for the migration of smooth muscle cells.

Animals↗
PubMed1998

2-Deoxyglucose inhibits chemotherapeutic drug-induced apoptosis in human monocytic leukemia U937 cells with inhibition of c-Jun N-terminal kinase 1/stress-activated protein kinase activation.

Human monocytic leukemia U937 cells undergo apoptosis when treated with antitumor drugs, such as etoposide, camptothecin and mitomycin C. The molecular mechanism of the drug-induced apoptosis is not well understood. In this study, we found that 2-deoxyglucose (2DG), an analog of D-glucose and an inducer of glucose-regulated stress, inhibited anticancer drug-induced but not tumor necrosis factor-alpha-induced apoptosis of U937 cells. 2DG did not reduce initial cellular damage caused by etoposide, an inhibitor of topoisomerase II, suggesting that 2DG affected subsequent cellular responses involved in apoptosis. 2DG inhibited the etoposide-induced activation of c-Jun N-terminal kinase 1/stress-activated protein kinase (JNK1/SAPK) and the subsequent activation of CPP32, both of which are positive regulators for etoposide-induced apoptosis of U937 cells. Our results indicate that 2DG inhibits apoptosis by blocking the signals from cellular DNA damage for JNK1/SAPK activation.

Antineoplastic Agents, Phytogenic↗
PubMed1998

Adult Sandhoff's disease: R505Q and I207V substitutions in the HEXB gene of the first Japanese case.

We describe a 31-year-old Japanese man with adult Sandhoff s disease presenting as spinocerebellar degeneration. There was a marked cerebellar atrophy on MRI, and proliferation of abundant PAS-positive foamy macrophages in the rectal mucosa. The activities of total beta-Hex, beta-Hex A, and beta-Hex B in leucocytes of the patient were 14%, 15%, and 6% of control values, respectively. However, oligosacchariduria or ultrastructural storage materials in liver tissue were nil. Direct sequencing of cDNA and genomic DNA, and restriction digestion revealed two different homozygous base substitutions in the HEXB gene: the G1514-->A substitution (R505Q) and the A619-->G substitution (1207V). The parents were consanguineous. His healthy mother, an enzymatic heterozygous carrier, was homozygous for 1207V, but heterozygous for R505Q mutation. Thus, the patient is probably homozygous for both base substitutions and a R505Q mutation may be linked to the phenotype of adult Sandhoff's disease.

Adult↗
PubMed1998

Production of germ-line chimeras by transfer of cryopreserved gonadal primordial germ cells (gPGCs) in chicken.

Gonadal primordial germ cells (gPGCs) were collected from gonadal anlage of 5-day-old White Leghorn (WL) embryos. Collected gPGCs were suspended in freezing medium containing 10% dimethyl sulphoxide (DMSO). The cell-suspension was frozen at 1 degree C/min until the temperature reached -80 degrees C; cells were then immersed in liquid nitrogen at -196 degrees C and stored up to 3 mo. Approximately 100 frozen/thawed gPGCs were injected into the dorsal aorta of each Barred Plymouth Rock (BPR) embryo from which blood was drawn prior to germ-cell injection. The injected embryos were incubated until hatched, and hatched chicks were raised until sexually mature. Upon reaching sexual maturity, a progeny test was performed by mating recipient chicks with normal BPR of the opposite sex. Of 840 progeny produced from 4 gPGC recipients, 74 chicks (8.8%) were phenotypically white. Present results demonstrate that frozen/thawed gPGCs collected from gonadal anlage are capable of producing germ-line chimeras in chicken.

Animals↗
PubMed1998

Distribution of heme oxygenase isoforms in rat liver. Topographic basis for carbon monoxide-mediated microvascular relaxation.

Carbon monoxide (CO) derived from heme oxygenase has recently been shown to play a role in controlling hepatobiliary function, but intrahepatic distribution of the enzyme is unknown. We examined distribution of two kinds of the heme oxygenase isoforms (HO-1 and HO-2) in rat liver immunohistochemically using monoclonal antibodies. The results showed that distribution of the two isoforms had distinct topographic patterns: HO-1, an inducible isoform, was observed only in Kupffer cells, while HO-2, a constitutive form, distributed to parenchymal cells, but not to Kupffer cells. Both isoforms were undetectable in hepatic stellate cells and sinusoidal endothelial cells. Of the two isoforms, HO-2 in the parenchymal cell rather than HO-1 in the Kupffer cell, appears to play a major role in regulation of microvascular tone. In the perfused liver, administration of HbO2, a CO-trapping reagent that can diffuse across the fenestrated endothelium into the space of Disse, elicited a marked sinusoidal constriction, while administration of a liposome-encapsulated Hb that cannot enter the space had no effect on the microvascular tone. These results suggest that CO evolved by HO-2 in the parenchymal cells, and, released to the extrasinusoidal space, served as the physiological relaxant for hepatic sinusoids.

Animals↗
PubMed1998

The novel fibronectin-binding motif and key residues of mycobacteria.

The binding motifs of the immunodominant antigen (Ag) alpha-Ag (Ag 85 complex B) of Mycobacterium kansasii for human fibronectin were examined using digested fragments. We defined two fibronectin-binding epitopes on 27 amino acids from 84 to 110 and on 20 amino acids from 211 to 230. The epitopes were almost conserved in the closely related Ag 85 complex of other mycobacteria species. Inhibition of fibronectin binding to intact alpha-Ag molecules was observed with peptide-(84-110), but not with peptide-(211-230). Peptide-(84-110) could also inhibit fibronectin binding to all components of the Ag 85 complex of Bacillus Calmette-Guérin (Ag 85A, Ag 85B, and Ag 85C). Further study with synthetic peptides defined 11 residues from 98 to 108 as the minimum motif. Six residues (98FEWYYQ103) were critical for interacting with fibronectin. The motif revealed no homology to other known prokaryotic and eukaryotic fibronectin-binding proteins. The defined motif of alpha-Ag is novel and unique for mycobacteria.

Amino Acid Sequence↗
PubMed1998

Genetically recessive mutant of human monocytic leukemia U937 resistant to tumor necrosis factor-alpha-induced apoptosis.

Tumor necrosis factor-alpha (TNF-alpha) is a cytokine that induces apoptosis in various cell systems by binding to the TNF receptor (TNFR). To study TNF-alpha-induced apoptosis, we isolated and characterized a novel TNF-alpha-resistant variant, U937/TNF clone UA, from human monocytic leukemia U937 cells. The UA cells resist apoptosis induced by TNF-alpha and anti-Fas antibody but not by anticancer drugs, such as VP-16 and Ara-C. Somatic cell hybridization between U937 and UA showed that apoptosis resistance to TNF-alpha in UA was genetically recessive. The hybridization analysis also showed that UA and another recessive mutant clone, UC, belong to different complementation groups in TNF-alpha-induced apoptosis signaling. In UA cells, TNF-alpha-induced disruption of mitochondrial membrane potential and CPP32 activation were abrogated. Expression of TNFR, Fas, and Bcl-2 family proteins was not changed in UA cells. These results suggest that the apoptosis resistant UA cells could have a functional defect in apoptosis signaling from the TNFR to mitochondria and interleukin-1beta converting enzyme (ICE) family protease activation. UA cells could be used to study signaling linkage between cell death-inducing receptor and mitochondria.

Apoptosis↗