Biomedical subjects

S Miyazaki

Publications and source records attributed to S Miyazaki.

At least 289 records · Page 16Linked to original sources

PubMed1997

Switch from conventional to high-flux membrane reduces the risk of carpal tunnel syndrome and mortality of hemodialysis patients.

The use of a high-flux membrane, which eliminates larger molecular weight solutes with better biocompatibility, has steadily increased since the discovery of beta-2 microglobulin (beta 2m) amyloidosis in 1985. The long-term effects of a dialyzer membrane on morbidity and mortality are not completely understood. To examine the membrane effect as a factor of carpal tunnel syndrome onset and mortality, multivariate Cox regression analysis with time-dependent covariate was conducted on 819 patients from March 1968 to November 1994 at a single center. Two hundred and forty-eight of the patients were either switched from the conventional to high-flux membrane or treated only with a high-flux membrane. Fifty-one patients underwent a CTS operation and 206 died. Membrane status (on high-flux or on conventional) was considered as time-dependent covariate and risk was adjusted for age, gender, type of renal disease and calendar year of dialysis initiation. The relative risk of CTS was reduced to 0.503 (P < 0.05) and mortality 0.613 (P < 0.05) by dialysis on the high-flux membrane, compared to the conventional membrane. Serial measurements of beta 2m indicated significantly lower beta 2m to persist in patients on the high-flux membrane. The high-flux membrane decreased the risk of morbidity and mortality substantially. Larger molecule elimination was shown important not only for preventing beta 2m amyloidosis, but for prolonging survival of dialysis patients as well.

Adult↗

PubMed1997

Effects of all-trans-retinoic acid on superoxide generation in intact neutrophils and a cell-free system.

To determine the pathophysiology of the retinoic acid syndrome which occurs during all-trans-retinoic acid (ATRA) treatment of acute promyelocytic leukaemia patients, we investigated the direct effects of ATRA on the function of human neutrophils. We found that ATRA (10-200 microM) dose-dependently stimulated superoxide (O2-) generation in intact neutrophils. The maximal activity of ATRA-stimulated O2- generation was 3.0 nmol/min/10(6) cells. Adding EGTA to the assay mixture did not affect the activity nor was the intracellular free calcium concentration changed upon stimulation. The treatment of neutrophils with 0.1 microM staurosporine, an antagonist of protein kinase C, for 10 min, enhanced the activity of ATRA-stimulated O2- generation up to 186% of that for control samples. Wortmannin (1 microM), an inhibitor of phosphatidylinositol 3-kinase (PI 3-kinase), reduced this stimulatory activity by 67%. These results suggest that ATRA activates the signalling pathway related to PI 3-kinase rather than that utilizing calcium and protein kinase C. ATRA enhanced the O2- generated in a sodium-dodecyl-sulphate (SDS) cell-free system, resulting in rates up to 288% higher than that seen with SDS alone. This enhancement was not affected by pretreatment with staurosporine or wortmannin. ATRA may thus directly activate and/or enhance the function of neutrophils.

Androstadienes↗

PubMed1997

Defective response to thrombopoietin and impaired expression of c-mpl mRNA of bone marrow cells in congenital amegakaryocytic thrombocytopenia.

Congenital amegakaryocytic thrombocytopenia (CAMT) is an uncommon disorder in newborns and infants, characterized by isolated thrombocytopenia and megakaryocytopenia in the first year without physical anomalies. The defect of thrombopoiesis is not well understood. Recently, thrombopoietin (TPO), the ligand for the c-mpl receptor, was cloned. Accumulating evidence from in vitro and in vivo studies indicate that TPO plays a key role in the regulation of megakaryocytopoiesis. In this study we examined the effect of TPO on megakaryocyte colony formation from a patient with CAMT using a plasma-containing methylcellulose clonal culture. The in vitro results demonstrated a defective response to TPO in megakaryocyte colony formation from bone marrow mononuclear cells (MNC) of the patient. although interleukin-3 (IL-3) but not stem cell factor (SCF) induced only a small number of megakaryocyte colonies. These findings indicated that thrombocytopenia in CAMT could not be corrected by administration of TPO in vitro. Additionally, clonal cultures containing SCF, IL-3, IL-6 and erythropoietin showed decreased numbers of erythroid and myelocytic progenitors in the bone marrow of the patient. The serum TPO level measured by enzyme-linked immunosorbent assay was significantly higher than that in healthy controls. By PCR, marrow MNC from healthy children and from a patient with essential thrombocytosis expressed c-mpl mRNA, whereas no c-mpl mRNA was detected in marrow MNC from the patient with CAMT. There was no difference in the CD34 expression and c-kit mRNA between the CAMT patient and healthy children. The results of this study suggest that the pathophysiology in CAMT may be a defective response to TPO in haemopoietic cells through impaired expression of c-mpl mRNA.

Bone Marrow↗

PubMed1997

New murine model of bronchopneumonia due to cell-bound Haemophilus influenzae.

This murine model of nontypeable (unencapsulated) Haemophilus influenzae (NTHI) bronchopneumonia used organisms bound to mouse fetal lung (MFL) cells as an inoculum. Pretreatment of the mice with 40 microL of 1% formalin 3 days before intranasal instillation of the bacteria was necessary to allow infection. The number of NTHI recovered from the lungs plus trachea on day 7 after instillation was >100 times the number originally inoculated. Later, however, the number of recovered bacteria diminished gradually, and by day 14 it was almost identical to the original inoculum size. Serum IgM also peaked on day 7 after infection, after which IgG increased while IgM decreased. Histologically, bronchoalveolar infiltration of neutrophils was observed on day 3 after inoculation and continued at least for the following 4 days. The present experiment demonstrates that MFL cells can protect bacteria that have invaded the cells from the opsonizing and killing activities of host humoral defense mechanisms.

Animals↗

PubMed1997

Is structural flexibility of antigen-binding loops involved in the affinity maturation of anti-DNA antibodies?

Effects of somatic mutations in Ig variable region genes on the affinity maturation of autoantibodies were investigated using single precursor B cell-derived anti-double-stranded DNA mAb generated from an autoimmune disease-prone (NZB x NZW)F1 mouse. Analyses of DNA sequences, homology modeling on a graphic computer and molecular dynamics simulation of antigen-binding sites showed that any single site of mutation and changes in the electrostatic or hydrogen-bonding potential of the residues and in the three-dimensional structure could not solely explain the difference in DNA-binding activities. However, a significant increase in the flexibility of antigen-binding Fv loops, particularly VL CDR1 and VH CDR3, was associated with affinity-maturated anti-DNA antibodies. Such high flexibility of the FV loops may provide the environment where the antibodies could effectively interact with antigen DNA, a model consistent with the 'induced-fit' hypothesis of antigen-antibody interactions.

Amino Acid Sequence↗

PubMed1997

Antibiotic MICs and short time-killing against Helicobacter pylori: therapeutic potential of kanamycin.

We compared the susceptibility of Helicobacter pylori to several antibiotics, expressed as MICs and as bactericidal effectiveness in short (3 h) time-killing studies. Of the antimicrobial agent tests, clarithromycin and amoxycillin had the lowest MIC50, 0.063 and 0.125 mg/L respectively, for 24 strains of H. pylori. Minocycline, levofloxacin and lansoprazole followed, with MIC50s of 0.5, 1, and 2 mg/L, respectively. Three-hour time-killing studies using a standard strain demonstrated a different pattern. At 4 x MIC, kanamycin, metronidazole and clarithromycin produced 4.4, 2.6 and 2.1 log decreases in viability, whereas the remaining seven antibiotics (including amoxycillin) were less bactericidal. Amoxycillin's lack of bactericidal activity during brief incubations was confirmed by examining several different clinically isolated H. pylori strains. Clarithromycin's effect, on the other hand, was strain- and concentration-dependent. Kanamycin was the most potent antibiotic in short time-killing studies, with concentrations of 1 x MIC and 4 x MIC producing a reduction of more than 2 and 4 log respectively in all ten strains. Our data suggest that the MIC of antimicrobial agents against H. pylori does not necessarily predict their activity in short time-killing studies. Furthermore, our short time-kill data suggest kanamycin as a potential therapeutic choice for H. pylori infection, even though this agent's MIC would suggest limited activity.

Amoxicillin↗

PubMed1997

Spatiotemporal dynamics of intracellular calcium in the mouse egg injected with a spermatozoon.

Oscillatory rises in intracellular Ca2+ concentration ([Ca2+]i) are the pivotal signal in the fertilization of mammalian eggs. The spatiotemporal dynamics of [Ca2+]i rises in mouse eggs subjected to intracytoplasmic sperm injection (ICSI) were analysed by Ca2+ imaging and compared with those subjected to in-vitro fertilization (IVF). The first Ca2+ transient occurred 15-30 min after ICSI in most eggs, and was followed by Ca2+ oscillations which lasted for at least 6 h at intervals of approximately 10 min. The pattern of Ca2+ oscillations, an initial relatively larger Ca2+ transient followed by smaller Ca2+ transients, was similar to that at fertilization. Confocal Ca2+ imaging during early Ca2+ transients showed that, in fertilized eggs, [Ca2+]i increased in a wave which started from the sperm attachment site and propagated across the egg cytoplasm. In eggs subjected to ICSI, [Ca2+]i increased gradually and then a Ca2+ spike was generated when [Ca2+]i reached a certain level. The [Ca2+]i rise occurred in the whole egg, associated with neither a wave nor significant heterogeneity between the cortical and central regions. It is suggested that cytosolic factor(s) may leak from the injected spermatozoon, diffuse slowly in the egg cytoplasm, and then cause a synchronous Ca2+ release from intracellular Ca2+ stores.

Animals↗

PubMed1997

Long-term unrestrained measurement of stride length and walking velocity utilizing a piezoelectric gyroscope.

Long-term monitoring of stride length and walking velocity is considered to provide useful information for making decisions on treatment of patients with gait disabilities. The purpose of this study was to develop a device with the following design criteria: lightweight, easy attachment, little hindrance to the natural gait pattern, sufficient memory to record for one day, and practicality in clinical use. The prototype consists of a piezoelectric gyroscope, which detects angular velocity of the thigh of one leg in the sagittal plane, and a microprocessor-based maximum/minimum detector/data logger of a cyclic analog signal associated with the gait cycle. The accuracy of the device was evaluated in 20 normal subjects, seven above-the-knee (A/K) amputees, and ten hemiplegic patients, and relative accuracy within +/-15% was obtained, except for two special cases.

Adult↗

PubMed1997

Rapid decrease of urinary pyridinoline excretion in growth hormone deficient children following discontinuation of growth hormone therapy.

In order to examine the effect of growth hormone on urinary pyridinoline excretion, 32 patients with complete or partial growth hormone deficiency had their urinary pyridinoline excretion measured while receiving growth hormone and for 14 days after it was discontinued. There was a significant positive correlation between increases in growth velocities during the first year of growth hormone administration compared to before it, and the ratio of the urinary pyridinoline excretion levels while receiving growth hormone to those after discontinuation. Therefore, urinary pyridinoline excretion rapidly decreased in patients with growth hormone deficiency when the administration of growth hormone was stopped. Exogenous growth hormone appears to stimulate bone resorption in these patients.

Adolescent↗

PubMed1997

A case of X-linked alpha-thalassemia/mental retardation syndrome: analysis of hemoglobin by an automated glycated hemoglobin analyzer.

A 5-year-old male patient with X-linked alpha-thalassemia/mental retardation syndrome is reported. He showed multiple minor anomalies including characteristic facial abnormalities, alpha-thalassemia, severe mental retardation, and hypogonadism. Analysis of his hemoglobin by high performance liquid chromatography using an automated glycated hemoglobin analyzer revealed an abnormal peak. Identification of an abnormal peak by an automated glycated hemoglobin analyzer will aid in the diagnosis of patients with X-linked alpha-thalassemia/mental retardation syndrome.

Abnormalities, Multiple↗

PubMed1997

An 11-year-old girl with reflex sympathetic dystrophy successfully treated by thoracoscopic sympathectomy.

We report on an 11-year-old girl with reflex sympathetic dystrophy (RSD) complaining of severe pain in her right upper extremity. Oral administration of narcotics or non-steroid anti-inflammatory drugs gave no relief in pain. Thoracoscopic electrocauterization of the thoracic sympathetic ganglion at the level of T3 was performed 3 months after the start of symptoms, and brought complete resolution of pain.

Arm↗

PubMed1997

In vitro and in vivo antibacterial activities of CS-940, a new fluoroquinolone, against isolates from patients with respiratory infections.

We compared the in vivo and in vitro activities of CS-940, a new fluoroquinolone, with those of a group of other drugs. The activities of CS-940 against gram-positive cocci and gram-negative rods, including methicillin-susceptible Staphylococcus aureus and penicillin-resistant Streptococcus pneumoniae, were comparable to those of tosufloxacin, with MICs at which 90% of the strains were inhibited (MIC90s) of 0.5 microg/ml or less. Against methicillin-resistant S. aureus, CS-940 was as active as tosufloxacin, with a MIC90 of 16 microg/ml. The efficacy of CS-940 against murine respiratory infections due to S. pneumoniae or Haemophilus influenzae was better than those of tosufloxacin and sparfloxacin. The efficacy of oral doses of CS-940 reflected not only potent in vitro activity but also a high transmigration ratio from the bloodstream to lung tissues.

Animals↗

PubMed1997

Immunomodulating effect of fosfomycin on gut-derived sepsis caused by Pseudomonas aeruginosa in mice.

We evaluated the protective effect of fosfomycin (FOM) and an enantiomer of fosfomycin [FOM (+); an isomer of FOM with no bactericidal activity] on murine gut-derived sepsis caused by Pseudomonas aeruginosa. Endogenous bacteremia was induced by administering cyclophosphamide (CY) and ampicillin to specific-pathogen-free mice fed P. aeruginosa. Treatment of mice with FOM at 250 mg/kg of body weight per day twice a day after the second CY administration significantly increased the survival rate compared to that for control mice treated with saline. Treatment with FOM (+) at 20 and 100 mg/kg also significantly increased the survival rate (from 30% for control mice to 80% for treated mice). The bacterial counts in the liver and blood were both significantly lower in FOM(+)-treated mice in comparison with those in liver and blood of saline-treated control mice. FOM(+) administration affected neither the bacterial colonization in the intestinal tract nor the leukocyte counts in the peripheral blood of the mice. After intravascular inoculation of P. aeruginosa, treatment of mice with FOM (+) did not enhance bacterial clearance from the blood of mice pretreated or not enhance bacterial clearance from the blood of mice pretreated or not pretreated with CY, FOM(+) significantly suppressed tumor necrosis factor alpha, interleukin-1 beta, and interleukin-6 levels in the serum of mice after gut-derived sepsis. These results indicate that both FOM and FOM(+) have protective effects against P. aeruginosa bacteremia, despite a lack of specific activity of FOM(+), and suggest that FOM may possess immunomodulating activity and that it induces a protective effect. The protective mechanism is speculated to be that FOM modulates the vivo production of inflammatory cytokines.

Adjuvants, Immunologic↗

PubMed1997

Effect of pulsed output ultrasound on the transdermal absorption of indomethacin from an ointment in rats.

The effect of pulsed output ultrasound (1 MHz) with on/off ratios of 1:2, 1:4 and 1:9 on transdermal absorption of indomethacin from an ointment was studied in rats. Ultrasound energy was supplied for between 10 and 19 min at a range of intensities (1.0-2.5 W.cm-2), energy levels commonly used for therapeutic purposes. The on/off pulsed ratio, intensity and the time of application were found to play an important role in the transdermal phonophoretic delivery system of indomethacin; 1:2 pulsed output ultrasound appeared to be the most effective in improving the transdermal absorption. The highest penetration was observed at an intensity of 1.0 W.cm-2 and application time of 15 min. With pulsed output it was possible to use higher intensities of ultrasound without increasing skin temperature or damaging skin.

Administration, Cutaneous↗

PubMed1997

[Preparation and evaluation of solid dispersions of pilocarpine hydrochloride for alleviation of xerostomia].

This investigation was carried out to try the application of pilocarpine hydrochloride (PC) solid dispersion as sustained release dosage form. Four preparations of PC with ethylcellulose and/or hydroxypropylmethylcellulose phthalate were prepared by the organic solvent method. The preparation D including PC: ethylcellulose: hydroxypropylmethylcellulose phthalate (1:9:10 at weight ratio) showed the best sustained release behavior in dissolution test among four preparations. The preparation D was examined by powder X-ray diffractometry and differential scanning calorimetry, and confirmed to be solid dispersion. Saliva secretory effect of preparation D was examined in healthy male volunteers, and its effect for Xerostomia was showed.

Cellulose↗

PubMed1997

Inflammatory pseudotumor of the liver--MR imaging findings.

Using retrospective studies, we have investigated the possibility of obtaining characteristic findings of inflammatory pseudotumor of the liver by magnetic resonance (MR) imaging. We examined 8 patients (involving 8 masses) who had been histologically diagnosed as having an inflammatory pseudotumor in the liver. The histological studies were performed on an excised specimen of 1 mass, and on aspiration needle biopsy specimens and the clinical courses of the other 7 masses. T1 weighted images (T1WI) and T2 weighted images (T2WI) were obtained on MR imaging. MR imagings were analyzed for visualized patterns, patterns of internal structure and patterns of contrast enhancement of dynamic MR imaging. The 8 masses were visualized as hypointense on T1WI and hyperintense on T2WI by MR imaging. Dynamic MR imaging revealed that 1 mass was markedly enhanced peripherally while another mass was homogeneously enhanced, and that enhancement was most marked immediately after injection of contrast medium and then gradually disappeared. Vessels were observed in 4 masses (the portal vein in 2 masses, the hepatic vein in 1 mass, and portal and hepatic veins in 1 mass), and these vessels were clearly visualized on T1WI. The MR imaging findings from the early stage of an inflammatory pseudotumor showed a pattern similar to that of hepatic tumors with rich blood flow. The portal vein or hepatic vein was found in the tumor in half the patients, suggesting that this characteristic was useful for diagnosis of an inflammatory pseudotumor in the liver.

Aged↗

PubMed1997

[Content determination of baicalin and baicalein in shuanghuanglian powdery injection by the method of HPLC-ECD].

The contents of baicalin and baicalein in Shuanghuanglian Powdery Injection have been determined by the method of HPLC-ECD under following conditions: column-ERC-ODS-1161, 6 mm x 100 mm; temperature-55 degrees C; mobile phase-0.1 mol/L KH2PO4, acetic acid and tetrahydrofuran (1000:100:190); flow rate-0.8 ml/min; detector voltage-+650 mV. The result shows the limit of detection for baicalin and baicalein to be 25 ng and 50 ng respectively, with an average recovery of 100.1% and 99.7% respectively. Highly reproducible, rapid, simple, convenient and accurate, this method is good for the content determination of baicalin and baicalein in Chinese medicinal herbs and preparations.

Chromatography, High Pressure Liquid↗

PubMed1997

Sympathetic nerve response to microgravity induced by parabolic flight.

The aim of this study was to clarify how muscle sympathetic nerve activity (MSNA) in humans, which plays an important role in blood pressure control against gravity, is altered under microgravity conditions. Subjects were seated in a jet aircraft with their legs extended. MSNA was recorded microneurographically from the tibial nerve of the sitting subjects with simultaneous monitoring of electrocardiogram, blood pressure, respiration, and intrathoracic blood volume during parabolic flights. In the Air Force training area, the aircraft made parabolas up to 10 times. At the entry to microgravity, intrathoracic blood volume increased, systemic blood pressure was elevated, and MSNA was suppressed. However, this MSNA suppression lasted only 10-15 sec, and then followed by an enhancement to the end of the parabolas. We conclude that MSNA is suppressed at the onset of microgravity during parabolic flight in response to loading of the cardiopulmonary volume receptor due to a cephalad body fluid shift. However, this MSNA suppression is transient during such dynamic gravitational changes as those induced by parabolic flight, probably modulated by arterial baroreceptors.

Adult↗