Biomedical subjects

T Kuroda

Publications and source records attributed to T Kuroda.

At least 91 records · Page 5Linked to original sources

PubMed2000

In vitro plasma protein binding and cellular uptake of ATX-S10(Na), a hydrophilic chlorin photosensitizer.

ATX-S10(Na), a hydrophilic chlorin photosensitizer having an absorption maximum at 670 nm, is a candidate second-generation photosensitizer for photodynamic therapy (PDT) for cancer treatment. In this study, we examined plasma protein binding, cellular uptake and subcellular targets of ATX-S10(Na) in vitro. Protein binding ratios of 50 microg / ml ATX-S10(Na) in rat, dog and human plasma were 73.0%, 87.2% and 97.7%, respectively. Gel filtration chromatography revealed that 1 mg / ml ATX-S10(Na) bound mainly to high-density lipoprotein (HDL) and serum albumin at the protein concentration of 0.4%, with binding ratios of 46% and 36%, respectively. The free form of ATX-S10(Na) was mostly incorporated into T.Tn cells, and its cellular uptake was partially but significantly inhibited by endocytosis inhibitors such as phenylarsine oxide, chloroquine, monensin and phenylglyoxal, and by chilling the cells to 4 degrees C. However, ouabain, harmaline, sodium cyanide, probenecid and aspartic acid did not influence the uptake of ATX-S10(Na), suggesting that cellular uptake of ATX-S10(Na) was not related to sodium-potassium pump activity, sodium-dependent transporter activity, mitochondrial oxidative respiration, organic anion transporter activity or aspartic acid transporter activity. By fluorescence microscopy, lysosomal localization of ATX-S10(Na) was observed in T.Tn cells. However, electron microscopic observation revealed that many subcellular organelles such as mitochondria, endoplasmic reticulum, ribosomes, Golgi complex and plasma membrane were damaged by PDT using 25 microg / ml ATX-S10(Na) soon after laser irradiation at 50 J / cm(2), and tumor necrosis was rapidly induced. This result indicated that ATX-S10(Na) was widely distributed within the cell.

Animals↗

PubMed2000

A two-component multidrug efflux pump, EbrAB, in Bacillus subtilis.

Genes (ebrAB) responsible for ethidium resistance were cloned from chromosomal DNA of Bacillus subtilis ATCC 9372. The recombinant plasmid produced elevated resistance against ethidium bromide, acriflavine, pyronine Y, and safranin O not only in Escherichia coli but also in B. subtilis. It also caused an elevated energy-dependent efflux of ethidium in E. coli. EbrA and EbrB showed high sequence similarity with members of the small multidrug resistance (SMR) family of multidrug efflux pumps. Neither ebrA nor ebrB was sufficient for resistance, but introduction of the two genes carried on different plasmids conferred drug resistance. Thus, both EbrA and EbrB appear to be necessary for activity of the multidrug efflux pump. In known members of the SMR family, only one gene produces drug efflux. Thus, EbrAB is a novel SMR family multidrug efflux pump with two components.

Acriflavine↗

PubMed2000

Jaw-tongue reflex: afferents, central pathways, and synaptic potentials in hypoglossal motoneurons in the cat.

The tongue position is reflexively controlled by the jaw position (the jaw-tongue reflex). The purpose of this study was to clarify the mechanism of this reflex in terms of afferents, central pathways, and synaptic potentials in hypoglossal motoneurons in the cat. Intracellular recordings from hypoglossal motoneurons revealed that electrical stimulation of the temporalis muscle nerve evoked excitatory and inhibitory post-synaptic potentials in hypoglossal motoneurons. The threshold of temporalis muscle nerve stimulation for evoking the synaptic potentials was higher than 2.0 times the nerve threshold. The amplitude of the potentials increased with stimulus intensity up to 5.0 times the nerve threshold. Punctate light pressure applied to the temporalis muscle induced a tonic depolarizing potential in hypoglossal motoneurons on which action potentials as well as depolarizing synaptic activation noise were superimposed. On the other hand, electrical stimulation of the temporalis muscle during jaw-opening could slightly inhibit the electromyographic activities in the genioglossus and styloglossus muscles. Lesions including the Probst's tract at the level caudal to the trigeminal motor nucleus abolished both excitation and inhibition in hypoglossal motoneurons induced by tonic depression of the lower jaw, but exerted no effects on either the tonic stretch reflex or the trigemino-hypoglossal reflex. In contrast, lesions including the trigeminal spinal tract produced no changes in either excitation or inhibition of hypoglossal motoneurons induced by temporalis muscle afferents, whereas the excitation of hypoglossal motoneurons was abolished by the lesions. We conclude that the group II muscle spindle afferents from the temporalis muscle are primarily responsible for evoking the jaw-tongue reflex.

Afferent Pathways↗

PubMed2000

Effects of head and body position on two- and three-dimensional configurations of the upper airway.

This study was carried out to test the hypothesis that changes in head/body position induce changes in upper-airway dimensions. Contiguous images were obtained by means of magnetic resonance imaging in normal awake subjects during nasal breathing. A statistical analysis was made on 5 consecutive slices, including the most constricted sites in both the retropalatal and retroglossal regions. Dimensional changes in the upper airway in association with changes in head/body position were evaluated. In the retropalatal region, there was a significant decrease in the lateral dimension in the lateral recumbent position compared with that in the supine position. The cross-sectional area in the retroglossal region was significantly increased in both the "supine with the head rotated" and "lateral recumbent" positions. This change was accompanied by significant volumetric changes in the retroglossal region. Thus, sleeping with the head rotated may be effective for improving upper-airway obstruction.

Adult↗

PubMed2000

Species differences in oral bioavailability of methotrexate between rats and monkeys.

The contributions of incomplete absorption and a first-pass effect to the low bioavailability (BA) of methotrexate (MTX) were evaluated pharmacokinetically in rats and monkeys which respectively have a lower and higher aldehyde oxidase (AO) activity than humans. Plasma concentration profiles of MTX in rats showed linear and nonlinear pharmacokinetics respectively after intravenous (i.v.) and oral dosing of 0.1, 0.5 or 2.5 mg/kg MTX. In rats, most of the dose was excreted as the parent compound into bile and urine after i.v. dosing of 0.5 mg/kg MTX, while the radioactivity was largely eliminated in expired air after oral dosing of 0.5 mg/kg 14C-MTX. Elimination in expired air fell markedly following antibiotics treatment. 7-Hydroxymethotrexate (7-OH-MTX), formed from MTX by AO, was detected in monkey plasma after i.v. and oral dosing of 0.5 mg/kg MTX, but not in rat plasma. The ratio of the cumulative urinary excretion of 7-OH-MTX to MTX in monkeys was higher after oral dosing than after i.v. dosing. The low BA in rats (10% at 0.5 mg/kg) was shown to be mainly due to incomplete absorption, including limited absorption and degradation to 2,4-diamino-N10-methylpteroic acid (DAMPA) and glutamic acid (Glu) by the carboxypeptidase of intestinal bacteria. The low BA in monkeys (5% at 0.5 mg/kg) was shown to be mainly due to the extensive first-pass effect, including metabolism to 7-OH-MTX.

Animals↗

PubMed2000

An efficient synthesis of the anti-asthmatic agent T-440: a selective N-alkylation of 2-pyridone.

6,7-Diethoxy-1-[1-(2-methoxyethyl)-2-oxo-1,2-dihydropyridin- 4-yl]naphthalene-2,3-dimethanol [T-440, (1)] is a potential anti-asthmatic agent based on selective phosphodiesterase 4 inhibition. It was necessary for the further evaluation of 1 to develop an efficient synthetic route for 1, especially the construction of the 1-(2-methoxyethyl)-2-pyridone moiety. We examined an N-selective alkylation of pyridone derivative (2) in basic media. 2-Methoxyethylation of 2 with 2-methoxyethyl iodide utilizing LiH as the base gave predominantly an N-alkyl pyridone derivative (3a) in 82% yield (N/O-alkylation=92/8), which is compatible with an ab initio calculation of transition-state structures for the methylation of 2-pyridone. Single crystallization of a crude mixture of 3a and 4a furnished pure 3a, which is a key synthetic intermediate of 1.

Alkylation↗

PubMed2000

[Influence of spontaneous otoacoustic emission (SOAE) on transiently evoked otoacoustic emission (TEOAE)].

The literature has reports on the influence of spontaneous otoacoustic emission (SOAE) on transiently evoked otoacoustic emission (TEOAE), but most do not take factors such as age, gender, and hearing level into consideration. We focused on these conditions. Subjects were 78 women with normal hearing aged 19 to 24 years (mean = 21.4). All had pure tone thresholds of 15 dB HL or better at 1 kHz, 2 kHz, and 4 kHz. ILO88 was used to record TEOAE and SOAE. Echo power (EP) and reproducibility (Repro) were compared between groups with and without SOAE. No significant audiometric difference was seen between groups. Total echo power (TEP) and whole reproducibility (WR) were significantly greater in the group having SOAE, consistent with previous reports (p < 0.01). EP and Repro classified by frequency bands were also significantly greater in the group having SOAE at 1 kHz to 4 kHz. Subjects were divided based on the number of SOAE and the above parameters compared. We found that as the SOAE number increased, EP and Repro increased. In conclusion, the existence of SOAE influences TEOAE parameters and must be taken into account during clinical testing.

Adult↗

PubMed2000

[A long-term follow-up case of multiple impacted teeth associated with large follicular cyst in maxilla].

Longitudinal record of a case of multiple impacted teeth associated with large follicular cyst in the right maxilla was presented. The patient was an 8-year-10-month-old girl whose chief complaint was delayed eruption of the right upper incisor. Clinical examination revealed a large follicular cyst in the right maxillary sinus, which greatly displaced teeth germs. Marsupialization followed by orthodontic extrusion successfully brought unerupted teeth into their positions. Greatly displaced upper right canine, which was as high as the floor of the orbit, erupted spontaneously after reduction of the lesion. During the subsequent years, the patient developed crowded dentition and reduced overbite, which needed additional orthodontic treatment with extraction of premolars. The patient was 26-years 8-months old upon completion of treatment. The surgical, orthodontic, and periodontological aspects of the case were reexamined. Marsupialization of dentigerous cysts can preserve impacted teeth, however, the outcome might be affected by several factors such as overall growth of facial bones.

Adult↗

PubMed2000

Clinical significance of anticentromere antibodies in patients with systemic lupus erythematosus.

OBJECTIVE: To clarify the clinical significance of anticentromere antibodies (ACA) in patients with systemic lupus erythematosus (SLE). METHODS: Two hundred sixteen patients with SLE who were treated in our department were surveyed cross sectionally for the presence of ACA using indirect immunofluorescence on HEp-2 cell lines. ACA were identified by their discrete speckled pattern. Antibodies to the major centromere protein, CENP-B, were also studied with ELISA. Serial determinations of anti-CENP-B were carried out using stored serum samples, if available. RESULTS: ACA were recognized in 12 (5.6%) patients with SLE. All patients were receiving steroid therapy, with a mean dose of prednisolone of 14.4 mg/day. These patients also tested positive for anti-CENP-B with high titers despite the low serological disease activity in most. Three or more CREST features were observed in 2 patients and 2 others had no such features. Both patients without CREST features had a relatively short disease duration. The age at onset of SLE was significantly higher and Raynaud's phenomenon was more frequent in patients with ACA than in patients without ACA. In 8 of 10 patients tested, retrospective analysis using stored sera revealed no consistent change in anti-CENP-B titers over time. CONCLUSION: The presence of ACA in patients with SLE is apparently more frequent than previously believed. Patients with SLE with ACA may be a distinct subgroup. A longterm followup is warranted to fully determine the clinical significance of ACA in patients with SLE.

Adolescent↗

PubMed2000

[A case of gastric cancer with multiple liver metastasis responding to combined chemotherapy with low-dose cisplatin and 5-fluorouracil].

A 68-year-old man who had Borrmann type 4 gastric cancer with multiple liver metastases was admitted to our hospital on October 20, 1998. He was considered nonresectable and placed on neoadjuvant chemotherapy consisting of low-dose CDDP and 5-FU. After 9 weeks of administration, the liver metastases had disappeared on abdominal computed tomography, but the primary lesion had progressed. On May 12, 1999, a total gastrectomy with a partial resection of the transverse colon and resectional biopsy of a white nodule of the liver were performed. This was a non-curative operation because of the peritoneal dissemination. A histopathological examination of the liver nodule revealed that the cancer cells had disappeared. The patient had an uneventful postoperative course and 4 weeks of chemotherapy were added. He remains alive with no symptoms or re-growth of the liver metastatic tumor 4 months after the surgery.

Adenocarcinoma↗

PubMed2000

Dexa-measured bone density changes over time after intertrochanteric hip fractures.

The local bone density after an intertrochanteric hip fracture changes over time. In this study, bone density was measured in proximal femur and third lumbar vertebrae in patients treated for an intertrochanteric hip fracture at various periods. There were 60 patients (mean age 71.4 years) and 50 control patients (mean age 62.4 years). Bone density measurements were performed with Dual energy X-ray absorptiometry (DEXA). Bilateral measurements of the greater trochanter, lesser trochanter and femoral diaphysis as well as the third lumbar vertebrae were performed. Each area showed different course of change. The bone density of the greater trochanter and the lesser trochanter in the injured side increased after three months as compared with the control. After three years, the bone density of the greater trochanter decreased. The bone density of the femoral diaphysis and the third vertebrae gradually decreased over time. The authors suggest that bone density changes under the influence of callus formation, bone remodeling, decrease in daily activity, and use of ambulatory aids, etc.

Absorptiometry, Photon↗

PubMed2000

Preservation of rat palatal scar tissue myofibroblasts in organ culture.

In order to modulate palatal scar tissue, especially its myofibroblastic component, there is a pressing need for an in vitro model of this tissue. In the present, study we established an organ culture model of the rat palatal scar tissue. After excision of palatal mucoperiosteum, explants from the developing immature scar tissue and from the normal palatal mucosa were used to observe myofibroblasts in vivo and their maintenance in organ culture. Explants were cultured at the gas-liquid interface in serum-free Waymouth's MB 752/1 medium and in a humid atmosphere containing 55% O2/5% CO2 in air at 37 degrees C for 3 days. Viability of the cultured explants was evaluated with morphological and histological criteria and BrdU incorporation. After organ culture, the scar tissue showed good preservation of the in vivo histology. The myofibroblasts and smooth muscle cells of the cultured scar tissues showed continuous expression of alpha-smooth muscle actin (alpha-SMA), mimicking the in vivo situation. In the normal tissues, only smooth muscle cells of the blood vessels expressed alpha-SMA. These results demonstrate that the established model provides a useful in vitro experimental tool for investigating the palatal scar tissue in general and its myofibroblasts in particular.

Actins↗

PubMed1999

Characterization of the LolA-LolB system as the general lipoprotein localization mechanism of Escherichia coli.

The major outer membrane lipoprotein (Lpp) of Escherichia coli requires LolA for its release from the cytoplasmic membrane, and LolB for its localization to the outer membrane. We examined the significance of the LolA-LolB system as to the outer membrane localization of other lipoproteins. All lipoproteins possessing an outer membrane-directed signal at the N-terminal second position were efficiently released from the inner membrane in the presence of LolA. Some lipoproteins were released in the absence of externally added LolA, albeit at a slower rate and to a lesser extent. This LolA-independent release was also strictly dependent on the outer membrane sorting signal. A lipoprotein-LolA complex was formed when the release took place in the presence of LolA, whereas lipoproteins released in the absence of LolA existed as heterogeneous complexes, suggesting that the release and the formation of a complex with LolA are distinct events. The release of LolB, an outer membrane lipoprotein functioning as the receptor for a lipoprotein-LolA complex, occurred with a trace amount of LolA, and therefore was extremely efficient. The LolA-dependent release of lipoproteins was found to be crucial for the specific incorporation of lipoproteins into the outer membrane, whereas lipoproteins released in the absence of LolA were nonspecifically and inefficiently incorporated into the membrane. The outer membrane incorporation of lipoproteins including LolB per se was dependent on LolB in the outer membrane. From these results, we conclude that lipoproteins in E. coli generally utilize the LolA-LolB system for efficient release from the inner membrane and specific localization to the outer membrane.

Bacterial Outer Membrane Proteins↗

PubMed1999

Different roles of two types of endothelin receptors in partial ablation-induced chronic renal failure in rats.

Recent work has drawn attention to endothelin as a likely contributor to renal pathogenesis. To elucidate the mechanism of progressive renal disease, we investigated the mRNA expression of endothelin and endothelin receptors, and the effect of endothelin ET(A), and/or ET(B) receptor antagonists on disease progression in the remnant kidney model. Proteinuria progressively increased in rats subjected to 5/6 nephrectomy (Nx) after 8 weeks (from 25+/-3 to 221+/-28 microg min(-1) kg(-1)). Creatinine clearance (Ccr) after renal ablation gradually decreased by 8 weeks (from 5.04+/-0.42 to 2. 68+/-0.26 ml min(-1) kg(-1)). Together with maximal proteinuria and decreased renal function, there was an increase in cortical mRNA expression of prepro endothelin-1 and endothelin ET(A) receptor expression, but a decrease in endothelin ET(B) receptor expression and in urinary excretion of endothelin-1. Administration (1-3 mg/day) of S-0139, (+)-disodium 27-[(E)-3-[2-[(E)-3-carboxylatoacryloylamino]-5-hydroxyphenyl]a crylay loxy]-3-oxoolean-12-en-28-oate, an endothelin ET(A) receptor-specific antagonist, had a beneficial effect on the evolution of the disease, preventing the appearance of intense proteinuria (113+/-11) and decreased Ccr (3.97+/-0.33). High blood pressure was observed in rats with 5/6 Nx and was decreased by S-0139 administration. To examine whether treatment modalities that decrease endothelin ET(B) receptor signaling have a deleterious effect on the kidney remnant, the effect of 97-618, an endothelin ET(B) receptor-specific antagonist, 4-tert-butyl-N-[5-(2-methoxyphenoxy)-6-(4-oxobutoxy)pyromidine+ ++-4-yl]b enzenesulfonamide, was also examined on the action of S-0139. Concomitant administration of S-0139 and 97-618 reversed the beneficial effect of S-0139 alone in the remnant kidney on proteinuria and renal functional impairment. These findings indicate that endothelin participates in the pathogenesis of proteinuria and glomerular injury and that an endothelin ET(A) receptor-specific antagonist could be useful in the treatment of some forms of human nephritis. The loss of endothelin ET(B) receptor seems to be important in the progression of renal disease.

Animals↗

PubMed1999

Hepatoma-derived growth factor-related protein (HRP)-1 gene in spermatogenesis in mice.

Hepatoma-derived growth factor (HDGF)-related protein (HRP)-1, a member of the HDGF gene family, showed testis-specific expression in mice. HRP-1 expression in spermatogenesis was analyzed in the testis of normal and azoospermic mice by Northern blot and immunohistochemistry. HRP-1 gene message was not expressed in the ovary and its product was detected only in the nuclei of germ cells, not in somatic cells. The HRP-1 gene is expressed through pachytene spermatocyte to round spermatid. HRP-1 gene expression was not detected in the testis of cryptorchid mice or in some strains of mutant mice. These findings suggest that the testis-specific HRP-1 gene may play an important role in the phase around meiotic cell division.

Animals↗

PubMed1999

Differential responses to parathyroid hormone-related protein (PTHrP) deficiency in the various craniofacial cartilages.

PTHrP null mutant mice exhibit skeletal abnormalities both in the craniofacial region and limbs. In the growth plate cartilage of the null mutant, a diminished number of proliferating chondrocytes and accelerated chondrocytic differentiation are observed. In order to examine the effect of PTHrP deficiency on the craniofacial morphology and highlight the differential feature of the composing cartilages, we examined the various cartilages in the craniofacial region of neonatal PTHrP deficient mice. The major part of the cartilaginous anterior cranial base appeared to be normal in the homozygous PTHrP deficient mice. However, acceleration of chondrocytic differentiation and endochondral bone formation was observed in the posterior part of the anterior cranial base and in the cranial base synchondroses. Ectopic bone formation was observed in the soft tissue-running mid-portion of the Meckel's cartilage, where the cartilage degenerates and converts to ligament in the course of normal development. The zonal structure of the mandibular condylar cartilage was scarcely affected, but the whole condyle was reduced in size. These results suggest the effect of PTHrP deficiency varies widely between the craniofacial cartilages, according to the differential features of each cartilage.

Animals↗

PubMed1999

Novel, potent, and selective phosphodiesterase-4 inhibitors as antiasthmatic agents: synthesis and biological activities of a series of 1-pyridylnaphthalene derivatives.

The structural requirements for potent and selective PDE4 inhibition were revealed in a 1-pyridylnaphthalene series, and the best compound (3kg, T-2585.HCl) was chosen for further biological evaluation (PDE4 inhibition IC50 = 0.13 nM, selectivity PDE3/4 ratio = 14 000). Compound 3kg showed potent antispasmogenic activities (ED50 = 0.063 mg/kg for reduction of antigen-induced bronchoconstriction, intravenously; ED50 = 0.033 mg/kg for reduction of histamine-induced bronchoconstriction, intraduodenally) in guinea pigs with little cardiovascular effects. Furthermore, 3kg induced significantly weaker emetic effects than RP73401 after oral administration in ferrets and intravenous administration in dogs (3kg, none of 4 ferrets vomited at a dose of 10 mg/kg, po and none of 8 dogs vomited at a dose of 0.3 mg/kg, iv; RP73401, 4 of 8 ferrets vomited at a dose of 3 mg/kg, po and 6 of 8 dogs vomited at a dose of 0.3 mg/kg, iv); that is compatible with the lower affinity for the high-affinity rolipram binding site (3kg, 2.6 nM; RP73401, 0. 85 nM). This may imply that 3kg has an improved therapeutic ratio because of a broad margin between the Ki value of binding affinity and the IC50 value of PDE4 inhibition (ratio = 0.050).

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed1999

Interferon-gamma inhibits the myofibroblastic phenotype of rat palatal fibroblasts induced by transforming growth factor-beta1 in vitro.

Interferon-gamma (IFN-gamma), a multifunctional cytokine, has been noted as a potential therapeutic agent for various fibrotic disorders, including excessive scar tissue formation. We previously reported that transforming growth factor-beta1 (TGF-beta1) induced the myofibroblastic phenotype in palatal fibroblasts derived from palatal mucosa, and that such effects might have a close link to palatal scar formation. In the present study, we examined the effects of IFN-gamma on TGF-beta1-pretreated palatal fibroblasts for the purpose of clarifying the suppressive potency against myofibroblastic phenotype expression in vitro. IFN-gamma significantly altered the spindle morphology of TGF-beta1-pretreated palatal fibroblasts into the polygonal one that was similar to the non-treated palatal fibroblasts. This change was parallel with a decrease in the expression of alpha-smooth muscle actin protein, a marker for myofibroblast, as determined by immunoblot analysis. Northern blot analysis showed that IFN-gamma inhibited proalpha2(I) collagen mRNA expression that was stimulated by TGF-beta1 pretreatment for 24 h. Furthermore, IFN-gamma decreased the cell contractility enhanced by TGF-beta1 pretreatment for 24 h in a three-dimensional collagen gel culture system. These results suggest that IFN-gamma may have negative effects with regard to controlling the myofibroblastic phenotype induced by TGF-beta1 in palatal fibroblasts.

Actins↗