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Y Yamamoto

Publications and source records attributed to Y Yamamoto.

At least 73 records · Page 4Linked to original sources
PubMed2004

Quantum teleportation with a quantum dot single photon source.

We report the experimental demonstration of a quantum teleportation protocol with a semiconductor single photon source. Two qubits, a target and an ancilla, each defined by a single photon occupying two optical modes (dual-rail qubit), were generated independently by the single photon source. Upon measurement of two modes from different qubits and postselection, the state of the two remaining modes was found to reproduce the state of the target qubit. In particular, the coherence between the target qubit modes was transferred to the output modes to a large extent. The observed fidelity is 80%, in agreement with the residual distinguishability between consecutive photons from the source. An improved version of this teleportation scheme using more ancillas is the building block of the recent Knill, Laflamme, and Milburn proposal for efficient linear optics quantum computation.

Journal Article↗
PubMed2004

Negligent homicide by traumatic asphyxia.

We presented an unusual case of negligent homicide by thorax compression, which is the expanded concept of traumatic asphyxia. A 58-year-old man was restrained in the prone position by six prison officers. They were ordered by their superiors to continue restraining him for about 15 min and the victim died. At the forensic autopsy, typical findings of thorax compression with intramuscular hemorrhages on the back and multiple fractures of the ribs were observed. No evidence of neck compression/smothering or other fatal issues likely to occur by chest compression was found. The reconstruction of the scene corresponded exactly with the localization of the injuries found in the victim. This is the first case of death by pure thorax compression without other fatal factors during intentional restraint, in which the force causing the chest compression was distinctly determined by the autopsy and reconstruction.

Asphyxia↗
PubMed2004

Additive antitumour effect of the epidermal growth factor receptor tyrosine kinase inhibitor gefitinib (Iressa, ZD1839) and the antioestrogen fulvestrant (Faslodex, ICI 182,780) in breast cancer cells.

A high expression level of epidermal growth factor receptor (EGFR)/HER1 has been suggested to lead to a shorter survival time and resistance to endocrine therapy in patients with breast cancer. To test the hypothesis that inhibition of the EGFR signalling pathway affects the antitumour effect of endocrine therapy, an EGFR tyrosine kinase inhibitor (EGFR-TKI), gefitinib, and an oestrogen receptor (ER) antagonist, fulvestrant, were administered to human breast cancer cells. A total of five human breast cancer cell lines were used. The effects of single or combined treatments with gefitinib and/or fulvestrant on cell growth, cell cycle progression and apoptosis were analysed. Changes in the expression levels of cyclin-dependent kinase inhibitors, p21 and p27, an antiapoptotic factor, Bcl-2, and a proapoptotic factor, Bax, were also investigated. All cell lines tested were sensitive to gefitinib (50% growth inhibitory concentration, 10-28.5 microM). Breast cancer cell lines with a high expression level of HER1 or HER2 were more sensitive to gefitinib than the others. Gefitinib induced a significant G1-S blockade in ER-positive KPL-3C cells. Gefitinib induced significant apoptosis in HER1-overexpressing MDA-MB-231 cells. Gefitinib additively increased the antitumour effect of fulvestrant in all three ER-positive cell lines in a medium supplemented with 17beta-oestradiol. The combined treatment promoted cell cycle retardation in KPL-3C cells, which is associated with an upregulation of p21 by fulvestrant and gefitinib, respectively. Apoptosis was associated with downregulation of Bcl-2 by gefitinib in MDA-MB-231 cells. These results suggest an additive interaction between the EGFR-TKI gefitinib and the antioestrogen fulvestrant in ER-positive breast cancer cells.

Antineoplastic Agents↗
PubMed2004

A new technique of microvascular suturing: the chopstick rest technique.

With the conventional techniques of tying knots during microvascular anastomosis or neural suturing, time may be lost due to various reasons. The loose end of the suture often falls down into the operative field and gets stuck to the surrounding tissues. In the process of retrieving the suture, the surrounding tissues can be picked up together with the suture. When the posterior wall technique [Br J Plast Surg 34 (1981) 47, Plast Reconstr Surg 69 (1982) 139, Microsurgery 8 (1987) 22, J Reconstr Microsurg 15 (1999) 321] is used, the loose end of the suture may be stuck to the backside of the vessel and may be hard to grab. In order to avoid those problems, a new way of tying a microsuture was developed. By avoiding contact of the loose end of the suture to the surrounding tissue at any point during tying, the microvascular anastomosis can be performed quicker and more efficiently.

Humans↗
PubMed2004

Neonatal manipulations of oxytocin alter expression of oxytocin and vasopressin immunoreactive cells in the paraventricular nucleus of the hypothalamus in a gender-specific manner.

Early postnatal manipulations of oxytocin have long-term behavioral and physiological consequences; the present study examined the hypothesis that oxytocin or its absence influences the subsequent expression of either oxytocin or arginine vasopressin in the CNS. On postnatal day 1 female and male prairie voles (Microtus ochrogaster) received a single i.p. injection of oxytocin (3 microg), oxytocin antagonist (0.3 microg), or 50 microl of isotonic saline or were only handled. On postnatal days 1, 8 and 21, brains were fixed, sectioned and stained for oxytocin or vasopressin immunoreactivity and analyzed as a function of age, treatment and sex. Both oxytocin and vasopressin immunoreactivity were observed on day 1 in the supraoptic and paraventricular nuclei (PVN) of the hypothalamus. Numbers of oxytocin and vasopressin neurons increased with age in both nuclei. Females treated on postnatal day 1 with oxytocin or oxytocin antagonist displayed a significant increase in oxytocin immunoreactivity on day 21 in the PVN. In contrast, males treated with antagonist tended to have decreased vasopressin immunoreactivity in the same region. These results revealed that the effects of neonatal manipulation of oxytocin are age-dependent, site-specific and sexually dimorphic. The long-lasting effects of neonatal exposure to exogenous oxytocin and oxytocin antagonist indicate a role for oxytocin in the development of the CNS during the neonatal period, affecting the development of the oxytocinergic system in females and the vasopressinergic system in males. The developmental effects observed suggest one possible mechanism by which neonatal exposure to oxytocin or neonatal inhibition of endogenous oxytocin produces long-lasting behavioral and physiological alterations and could play a role in the development of male- and female-typical behavior.

Animals↗
PubMed2004

Development of a phantom compatible for MRI and hyperthermia using carrageenan gel--relationship between dielectric properties and NaCl concentration.

A phantom has previously been developed containing carrageenan, agarose and gadolinium chloride (called CAG phantom) for MRI with 1.5 T. T(1) and T(2) relaxation times of this phantom are independently changeable by varying concentrations of relaxation-time modifiers to simulate relaxation times of the various types of human tissues. The CAG phantom has a T(1) value of 202-1904 ms and a T(2) value of 38-423 ms, when the GdCl(3) concentration is varied from 0-140 micromol/kg and the agarose concentration is varied from 0-1.6%. A new phantom has now been developed (called CAGN phantom), made by adding an electric conductive agent, NaCl, to the CAG phantom for use in the areas of MRI and hyperthermia research. Dielectric properties of the CAGN phantom were measured and the results of experiments were expressed by the Cole-Cole equation in the frequency range of 5-130 MHz. The relationship between the conductivity of the CAGN phantom and the concentration of NaCl was expressed by a linear function in the frequency range of 1-130 MHz. The linear function involves a parameter of frequency and, when the frequency is 10 MHz, the conductivity of the CAGN phantom can be changed from 0.27-1.26 Sm(-1) by increasing the NaCl concentration from 0-0.7%. The CAGN phantom developed can be employed in basic experiments for non-invasive temperature measurement using MRI and as a loading phantom for MRI with up to 3 T.

Carrageenan↗
PubMed2004

Cardiopulmonary haemodynamic changes after severe head injury.

Haemodynamic studies were performed by pulmonary artery catheter in 15 patients with severe head injury. To our knowledge, few data are available about the detailed haemodynamic changes after head injury using pulmonary artery catheter. All patients were assessed by the Glasgow Coma Scale, computed tomography and intracranial pressure monitoring. We divided the patients into hypotensive and normotensive groups. All patients showed a high pulmonary vascular resistance and a high pulmonary capillary wedge pressure, probably due to pulmonary vasoconstriction. In the hypotensive group, the two major changes were a marked decrease of the cardiac index and a slight increase of systemic vascular resistance. The low cardiac index was the result of heart failure secondary to myocardial dysfunction. In contrast, the normotensive group was characterized by a high systemic vascular resistance that was induced by generalized vasoconstriction. Increased intracranial pressure is initially associated with an increase of the cardiac index and systemic vascular resistance, so patients with severe head injury also suffer from profound circulatory disturbance.

Adult↗
PubMed2004

Quantitative detection of periodontal pathogens using real-time polymerase chain reaction with TaqMan probes.

Quantitative analysis, with identification of periodontopathic bacteria, is important for the diagnosis, therapeutic evaluation and risk assessment of periodontal disease. We developed a highly sensitive and specific method using real-time polymerase chain reaction (PCR) to detect and quantify six periodontal bacteria: Porphyromonas gingivalis, Tannerella forsythia, Actinobacillus actinomycetemcomitans, Treponema denticola, Prevotella intermedia, and Prevotella nigrescens. Species-specific TaqMan probe/primer sets were designed according to 16S ribosomal RNA gene sequences. Plaque and tongue debris specimens were collected from 10 patients with advanced periodontitis and 10 periodontal healthy individuals and analyzed. All species, except for P. nigrescens, were detected in samples from diseased sites in significantly greater numbers than in those from healthy sites, whereas greater numbers of P. nigrescens were found in the controls. These results suggest that the present real-time PCR method with the designed probe/primer sets enabled sensitive detection of the six periodontal bacteria, and may also assist future microbial studies of periodontal diseases.

Aggregatibacter actinomycetemcomitans↗
PubMed2004

Usefulness of synthetic phospholipid in measurement of activated partial thromboplastin time: a new preparation procedure to reduce batch difference.

Commercial activated partial thromboplastin time (APTT) reagents prepared with phospholipid extracted from animal or plant sources often differ in their response to heparin and coagulation factors and in their reference values. It is also known that there are variations in phospholipid composition and preparation procedure. The present study attempted to demonstrate that an APTT reagent based on synthetic phospholipids (phosphatidylethanolamine, phosphatidylcholine and phosphatidylserine), which are substances of high purity and homogeneity, reduces batch-to-batch difference when compared with two traditional APTT reagents derived from rabbit brain and soybean. Three types of APTT reagent (SYN-APTT, RBT-APTT, SOY-APTT), prepared respectively from synthetic phospholipid, rabbit brain, and soybean, were tested. The total batch-to-batch difference was coefficient of variation (CV) 0.7-2.4% in the five reagents prepared from synthetic phospholipid (SYN-APTT), but CV 1.5-10.3% in the two traditional reagents (RBT-APTT and SOY-APTT). Additionally, high-performance liquid chromatography (HPLC) analysis showed clear variation in the phospholipid composition of the RBT-APTT and SOY-APTT reagents. In conclusion, the SYN-APTT reagent derived from synthetic phospholipid was shown to reduce batch-to-batch difference, and we therefore suggest that synthetic phospholipid is a substance useful in the preparation of APTT reagent and could contribute to stability of supply and uniform diagnosis.

Animals↗
PubMed2004

Pre-decondensed sperm head injections into female pronuclei result in chromosomal mingling, zygotic cleavage, and adequate embryonic and fetal development up to delivery of healthy offspring: a novel method of assisted syngamy.

Investigation of the developmental potential post-injection of a pre-decondensed or non-pre-decondensed sperm head into the female pronucleus of a pre-activated oocyte. Rat pre-activated oocytes were treated with intrapronuclear pre-decondensed sperm head injections (IPSHI) (n = 133) or intrapronuclear non-pre-decondensed sperm head injections (INPSHI) (n = 138). All injected oocytes were transferred to pseudopregnant female recipients. Rat IPSHI techniques resulted in the delivery of five healthy offspring. Rat INPSHI techniques did not result in any pregnancies. Rat IPSHI techniques can result in delivery of healthy offspring. Successful performance of human IPSHI techniques might serve as a novel method to manage cases of intracytoplasmic sperm injection failure due to lack of development of male pronucleus or due to failure in pronuclei fusion.

Animals↗
PubMed2004

Streptococcus mutans strains harboring collagen-binding adhesin.

A previously unidentified 120-kDa protein was detected in Streptococcus mutans strain Z1 and was involved in the cold-agglutination of the strain. We have identified the gene, designated cnm, as being involved in the agglutination of strain Z1 following random mutagenesis. The amino acid sequence of the deduced Cnm protein exhibited high similarity to those of collagen-binding adhesins from staphylococci and other organisms. To confirm whether the protein is involved in collagen-binding, we cloned a cnm gene fragment, overexpressed it in E.coli, and prepared crude extracts. The extracts containing recombinant protein exhibited binding to immobilized collagen and laminin but not to fibronectin. Compared with the parental strain Z1, the cold-agglutination-negative mutant 05A02 exhibited reduced binding to collagen and laminin but retained that to fibronectin. This gene was detected in some strains of S. mutans. Therefore, the cnm gene encoded a new strain-specific member of the collagen-binding adhesin family.

Adhesins, Bacterial↗
PubMed2004

Decreased fractal correlation in diurnal physical activity in chronic fatigue syndrome.

OBJECTIVES: Our objectives were to study the temporal correlation of physical activity time series in patients with chronic fatigue syndrome (CFS) during normal daily life and to examine if it could identify the altered physical activity in these patients. METHODS: Fractal scaling exponents of diurnal and nocturnal physical activity time series in 10 CFS patients and 6 healthy control subjects (CON) were calculated by the detrended fluctuation analysis (DFA) and the wavelet transform modulus maxima (WTMM) method. We hypothesized that, due to their illness- and/or fatigue-induced resting episodes, altered physical activity patterns in CFS patients might be observed at the interruption of activity bursts. Thus, we further developed a new method, the wavelet transform negative modulus maxima (WTNMM) method, which could evaluate the temporal correlation at the interruption of activities. We compared the fractal scaling exponents for CFS and CON by each method. RESULTS: Both for CFS and CON, we found the fractal time structures in their diurnal physical activity records for at least up to 35 minutes. No group difference was found in nocturnal activities. The WTNMM method revealed that, in diurnal activities, CFS patients had significantly (p < 0.01) smaller fractal scaling exponent (0.87 +/- 0.03) compared to controls (1.01 +/- 0.03). Such a difference was identified neither by the DFA nor WTMM method. CONCLUSIONS: CFS patients had more abrupt interruptions of voluntary physical activity during diurnal periods in normal daily life, probed by the decreased correlation in the negative modulus maxima of the wavelet-transformed activity data, possibly due to their exaggerated fatigue.

Chronic Disease↗
PubMed2004

Adverse effects of energy restriction on changes in immunoglobulins and complements during weight reduction in judoists.

AIM: A preliminary study to investigate the combined effects of dietary restriction and weight reduction through exercise on markers of immune function in college judoists before and after a single competition. METHODS: Forty-nine judoists participated in the study. Thirty-eight athletes combined exercise and dietary restriction (WR group), and 11 athletes did not require dietary restriction (EX group). Changes in anthropometric parameters, energy intake, concentrations of serum immunoglobulins and complements, and white blood cell counts were assessed at 4 time points: 20 days (pre-values), 4 days and 1 day before the competition, and 7 days after the competition. RESULTS: Compared with pre-values, the WR group exhibited significant decreases in body weight (-2.8 kg at 1 day before) and fat free mass (-1.7 kg at 1 day before); there were no changes in these variables in the EX group. The WR group exhibited significant decreases in IgG, IgM and C3 at 7 days after the competition (all p<0.01). In the EX group, significant decreases in IgM and C3 (both p<0.05) were observed at 7 days after the competition, though to a lesser degree than in the WR group. CONCLUSIONS: Energy restriction seemed to exacerbate alterations in immune markers such as immunoglobulin and complement induced by vigorous exercise at 7 days after a competition. Although the changed values were still within normal limits, we hypothesize that the potential cumulative effect of these changes over many competitions in 1 year might well induce abnormal levels with a possibly harmful clinical effect on judoists.

Adult↗
PubMed2003

Augmented cytoplasmic Smad4 induces acceleration of TGF-beta1 signaling in renal tubulointerstitial cells of hereditary nephrotic ICGN mice with chronic renal fibrosis; possible role for myofibroblastic differentiation.

The Institute of Cancer Research (ICR)-derived glomerulonephritis (ICGN) mouse is a hereditary model animal for nephrotic syndrome with chronic renal tubulointerstitial fibrosis. In most fibrotic diseases, myofibroblastic differentiation is considered to play crucial roles in pathogenesis of fibrosis and is dominantly regulated by the transforming growth factor (TGF)-beta1 signaling system. To reveal the pathogenic mechanism of chronic renal fibrosis in ICGN mice, we examined the expression and localization of TGF-beta1 signal transducer proteins (TGF-beta receptor-I and -II, Smad2/3 and Smad4) in kidney sections and in primarily cultured tubulointerstitial fibroblasts (TIFs). In kidneys of ICGN mice, many tubulointerstitial cells were differentiated to myofibroblastic cells and were alpha-smooth muscle actin (alphaSMA)-positive. The numbers of alphaSMA-positive TIFs prepared from kidneys of ICGN mice (ICGN-TIFs), but not those of ICR control mice (ICR-TIFs), increased during cell culture. No significant differences in production or activation of TGF-beta1 between ICGN-TIFs and ICR-TIFs were seen by enzyme-linked immunosorbent assay. In vitro transcriptional reporter assay for TGF-beta1 and Western immunoblotting for TGF-beta1 signal transducers showed no notable differences in the expression levels of TGF-beta receptor-I or -II or Smad2/3 between these TIFs. However, augmented cytoplasmic Smad4 protein in ICGN-TIFs, but not ICR-TIFs, seemed to cause hypersensitivity against TGF-beta1, and the eventual nuclear localization of Smad2/3-Smad4 complex was increased in ICGN-TIFs. Thus, the abnormal cytoplasmic augmentation of Smad4 induces acceleration of TGF-beta1 signaling in the renal tubulointerstitial cells of ICGN mice.

Animals↗
PubMed2003

Two types of rhythm in the respiratory network output in the isolated ventrolateral medulla in the neonatal rats.

Effects of substance P and extracellular [K(+)](o) on respiratory motor activity in the ventrolateral medulla in neonatal rat (0-4 days old) brainstem-spinal cord preparation were studied. In addition to fictive eupneic rhythm (8-13 bursts/minute), the respiratory motor output was composed of biphasic bursts which might underlie the sigh pattern in vivo. These bursts had considerably lower frequency (0.15-0.86 bursts/minute) and appeared when inspiratory neurons generated augmented biphasic discharges. The two rhythms were differently affected when the respiratory network excitability was increased by substance P or decreased by lowering external [K(+)](o), the effects on biphasic burst frequency being considerably greater. The augmented bursts could suppress inspiratory, but not pre-inspiratory neuron discharge, suggesting that pre-inspiratory neurons formed a supplementary rhythmic network which was not directly affected by biphasic burst generation.

Animals↗
PubMed2003

Mitral valve injury during balloon valvuloplasty for an infant with severe aortic stenosis: spatial evaluation using three-dimensional echocardiography.

We report on a 4-month-old infant with mitral valve injury that was induced by percutaneous balloon valvuloplasty for severe aortic valve stenosis. Three-dimensional echocardiography revealed a laceration at the anterior leaflet of the mitral valve. The mitral valve injury was successfully repaired by surgical operation 1 year after the valvuloplasty. This unexpected complication is associated with anatomical disorders of congenital aortic stenosis, including hypoplastic left ventricle, short chordae tendae, and large papillary muscles.

Aortic Valve Stenosis↗