Abdominal aortic aneurysm screening reduces mortality: meta-analyses of randomized, controlled trials.
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Aged↗
Biomedical subjects
N Kawai
Publications and source records attributed to N Kawai.
An optical spectrum of the afterglow of a gamma-ray burst at a redshift of z = 6.295.
The prompt gamma-ray emission from gamma-ray bursts (GRBs) should be detectable out to distances of z > 10 (ref. 1), and should therefore provide an excellent probe of the evolution of cosmic star formation, reionization of the intergalactic medium, and the metal enrichment history of the Universe. Hitherto, the highest measured redshift for a GRB has been z = 4.50 (ref. 5). Here we report the optical spectrum of the afterglow of GRB 050904 obtained 3.4 days after the burst; the spectrum shows a clear continuum at the long-wavelength end of the spectrum with a sharp cut-off at around 9,000 A due to Lyman alpha absorption at z approximately 6.3 (with a damping wing). A system of absorption lines of heavy elements at z = 6.295 +/- 0.002 was also detected, yielding the precise measurement of the redshift. The Si ii fine-structure lines suggest a dense, metal-enriched environment around the progenitor of the GRB.
Journal Article↗
Early hemostatic therapy using recombinant factor VIIa in a collagenase-induced intracerebral hemorrhage model in rats.
Neurological deterioration during the first day after intracerebral hemorrhage (ICH) is associated with early hematoma growth in 18 to 38% of patients. While clinical studies continue to evaluate efficacy of activated recombinant factor VII (rFVlla) for reducing frequency of early hematoma growth, there have been no studies investigating the effect of rFVIIa on early hematoma growth. We used a collagenase-induced ICH model in the rat to evaluate the effects of rFVIIa on early hematoma growth. Two hours after injection of 0.14 U of type IV bacterial collagenase in 10 microL of saline into the basal ganglia, a small amount of blood collected in the striatum. The ICH gradually increased in size, extending posteriorly to the thalamus by 24 hours after injection. Intravenous administration of rFVIIa immediately after collagenase injection decreased average hematoma volume at 24 hours compared with vehicle-treated group (168.1 +/- 13.4 mm3 vs. 118.3 +/- 23.0 mm3, p < 0.01). There was also a decrease in total hemoglobin content in rats treated with rFVlla compared with vehicle-treated rats (optical density at 550 nm: 0.87 +/- 0.08 vs. 0.71 +/- 0.09, p < 0.05). There was no difference in cortical brain water content overlying the hematoma between the rFVlla- and vehicle-treated groups (81.4 +/- 0.7% vs. 81.7 +/- 0.4%). Our study indicates that treatment with rFVIla may be useful in reducing the frequency of early hematoma growth in ICH patients.
Animals↗
The afterglow of GRB 050709 and the nature of the short-hard gamma-ray bursts.
The final chapter in the long-standing mystery of the gamma-ray bursts (GRBs) centres on the origin of the short-hard class of bursts, which are suspected on theoretical grounds to result from the coalescence of neutron-star or black-hole binary systems. Numerous searches for the afterglows of short-hard bursts have been made, galvanized by the revolution in our understanding of long-duration GRBs that followed the discovery in 1997 of their broadband (X-ray, optical and radio) afterglow emission. Here we present the discovery of the X-ray afterglow of a short-hard burst, GRB 050709, whose accurate position allows us to associate it unambiguously with a star-forming galaxy at redshift z = 0.160, and whose optical lightcurve definitively excludes a supernova association. Together with results from three other recent short-hard bursts, this suggests that short-hard bursts release much less energy than the long-duration GRBs. Models requiring young stellar populations, such as magnetars and collapsars, are ruled out, while coalescing degenerate binaries remain the most promising progenitor candidates.
Journal Article↗
Discovery of the short gamma-ray burst GRB 050709.
Gamma-ray bursts (GRBs) fall into two classes: short-hard and long-soft bursts. The latter are now known to have X-ray and optical afterglows, to occur at cosmological distances in star-forming galaxies, and to be associated with the explosion of massive stars. In contrast, the distance scale, the energy scale and the progenitors of the short bursts have remained a mystery. Here we report the discovery of a short-hard burst whose accurate localization has led to follow-up observations that have identified the X-ray afterglow and (for the first time) the optical afterglow of a short-hard burst; this in turn led to the identification of the host galaxy of the burst as a late-type galaxy at z = 0.16 (ref. 10). These results show that at least some short-hard bursts occur at cosmological distances in the outskirts of galaxies, and are likely to be caused by the merging of compact binaries.
Journal Article↗
Detection of a radio counterpart to the 27 December 2004 giant flare from SGR 1806-20.
It was established over a decade ago that the remarkable high-energy transients known as soft gamma-ray repeaters (SGRs) are located in our Galaxy and originate from neutron stars with intense (< or = 10(15)G) magnetic fields-so-called 'magnetars'. On 27 December 2004, a giant flare with a fluence exceeding 0.3 erg cm(-2) was detected from SGR 1806-20. Here we report the detection of a fading radio counterpart to this event. We began a monitoring programme from 0.2 to 250 GHz and obtained a high-resolution 21-cm radio spectrum that traces the intervening interstellar neutral hydrogen clouds. Analysis of the spectrum yields the first direct distance measurement of SGR 1806-20: the source is located at a distance greater than 6.4 kpc and we argue that it is nearer than 9.8 kpc. If correct, our distance estimate lowers the total energy of the explosion and relaxes the demands on theoretical models. The energetics and the rapid decay of the radio source are not compatible with the afterglow model that is usually invoked for gamma-ray bursts. Instead, we suggest that the rapidly decaying radio emission arises from the debris ejected during the explosion.
Journal Article↗
Fibre-type composition of rabbit jaw muscles is related to their daily activity.
Skeletal muscles contain a mixture of fibres with different contractile properties, such as maximum force, contraction velocity and fatigability. Muscles adapt to altered functional demands, for example, by changing their fibre-type composition. This fibre-type composition can be changed by the frequency, duration and presumably the intensity of activation. The aim of this study was to analyse the relationship between the spontaneous daily muscle activation and fibre-type composition in rabbit jaw muscles. Using radio-telemetry combined with electromyography, the daily activity of five jaw muscles was characterized in terms of the total duration of muscle activity (duty time) and the number of activity bursts. Fibre-type composition of the muscles was classified by analysing the myosin heavy chain content of the fibres. The amount of slow-type fibres was positively correlated to the duty time and the number of bursts only for activations exceeding 20-30% of the maximum activity per day. Furthermore, cross-sectional areas of the slow-type fibres were positively correlated to the duty time for activations exceeding 30% of the maximum activity. The present data indicate that the amount of activation above a threshold (> 30% peak activity) is important for determining the fibre-type composition and cross-sectional area of slow-type fibres of a muscle. Activation above this threshold occurred only around 2% of the time in the jaw muscles, suggesting that contractile properties of muscle fibres are maintained by a relatively small number of powerful contractions per day.
Animals↗
Burst characteristics of daily jaw muscle activity in juvenile rabbits.
Muscle activation varies with different behaviors and can be quantified by the level and duration of activity bursts. Jaw muscles undergo large anatomical changes during maturation, which are presumably associated with changes in daily muscle function. Our aim was to examine the daily burst number, burst length distribution and duty time (fraction of the day during which a muscle was active) of the jaw muscles of juvenile male rabbits (Oryctolagus cuniculus). A radio-telemetric device was implanted to record muscle activity continuously from the digastric, superficial and deep masseter, medial pterygoid and temporalis during maturation week 9-14. Daily burst characteristics and duty times were determined for activations, including both powerful and non-powerful motor behavior. All muscles showed constant burst numbers, mean burst lengths and duty times during the recording period. Including all behavior, the temporalis showed significantly larger daily burst numbers (205,000) and duty times (18.2%) than the superficial and deep masseter (90,000; 7.5%). Burst numbers and duty times were similar for the digastric (120,000; 11.1%) and medial pterygoid (115,000; 10.4%). The temporalis and deep masseter showed many short low activity bursts (0.05 s), the digastric showed many long bursts (0.09 s). For activations during powerful behaviors the superficial masseter and medial pterygoid had the largest burst numbers and duty times. Both muscles showed similar burst characteristics for all activation levels. It was concluded that activation of the jaw muscles is differently controlled during powerful and non-powerful motor behaviors and the functional organization of motor control patterns does not vary from 9 to 14 weeks of age.
Action Potentials↗
The frictional coefficient of the temporomandibular joint and its dependency on the magnitude and duration of joint loading.
In synovial joints, friction between articular surfaces leads to shear stress within the cartilaginous tissue, which might result in tissue rupture and failure. Joint friction depends on synovial lubrication of the articular surfaces, which can be altered due to compressive loading. Therefore, we hypothesized that the frictional coefficient of the temporomandibular joint (TMJ) is affected by the magnitude and duration of loading. We tested this by measuring the frictional coefficient in 20 intact porcine TMJs using a pendulum-type friction tester. The mean frictional coefficient was 0.0145 (SD 0.0027) after a constant loading of 50 N during 5 sec. The frictional coefficient increased with the length of the preceding loading duration and exceeded 0.0220 (SD 0.0014) after 1 hr. Application of larger loading (80 N) resulted in significantly larger frictional coefficients. In conclusion, the frictional coefficient in the TMJ was proportional to the magnitude and duration of joint loading.
Algorithms↗
Shear properties of the temporomandibular joint disc in relation to compressive and shear strain.
Shear stress can result in fatigue, damage, and irreversible deformation of the temporomandibular joint disc. Insight into the dynamic shear properties of the disc may give insight into the mechanism inducing tissue failure due to shear. We tested the hypothesis that the dynamic shear properties of the disc depend on the amount of shear and compressive strain. Twenty-four porcine discs were used for dynamic shear tests. The specimens were clamped between the plates of a loading apparatus under compressive strains of 5%, 10%, and 15%. Dynamic shear was applied to the specimen by a sinusoidal strain of, respectively, 0.5%, 1.0%, and 1.5%. Both the dynamic elasticity and viscosity were proportional to compressive strain and inversely proportional to shear strain. These shear characteristics suggest a significant role of compressive and shear strain on the internal friction of the disc.
Algorithms↗
Radiographic examination of dentigerous cysts in the transitional dentition.
OBJECTIVES: To examine radiographically the relationship between the deciduous tooth and dentigerous cyst of the permanent successor during the transitional dentition. METHODS: From a retrospective review of all patients who visited our institution from April 1988 to August 2001, 70 patients under 16 years of age who had histologically confirmed dentigerous cysts that had developed from the central incisor to the second premolar were identified. These 70 patients were investigated using panoramic and periapical radiographs. RESULTS: In most cases (54 cases; 77.1%) the cyst was in the premolar region. Of the 54 premolars with dentigerous cysts, the overlying deciduous tooth had already been lost in 7 cases. Of the 47 remaining premolars with associated deciduous tooth, 35 (74.5%) had bone resorption of the periapical or bifurcation region, or irregular resorption of the associated deciduous tooth. Of the remaining 12 deciduous teeth with no periapical lesions, 9 had been treated with root canal therapy. Thus, 44 of these 47 cases (93.6%) had the possibility of inflammation at the deciduous tooth associated with the dentigerous cyst. Evidence from one case in the present study suggesting the process by which cyst development occurs is also given. CONCLUSION: Inflammatory change at the apex of the deciduous tooth may bring on a dentigerous cyst of the permanent successor.
Adolescent↗
Treatment of cold injury-induced brain edema with a nonspecific matrix metalloproteinase inhibitor MMI270 in rats.
Blood-brain barrier (BBB) disruption is a critical event leading to vasogenic brain edema and secondary brain damage after cold injury-induced brain trauma. Matrix metalloproteinases (MMPs) are implicated in BBB disruption in this model. The purpose of this study was to examine the effects of MMI270, a synthetic nonspecific MMP inhibitor, on cold injury-induced brain edema in rats. Treatment with MMI270, a bolus injection at a dose of 30 mg/kg, was started immediately after the induction of cold injury and was continued at a dose of 40 mg/kg/day using an intraperitoneal osmotic minipump. At 24 hours after the cold injury, the brain water content and the BBB permeability to Evans Blue (EB) were determined. The secondary brain lesion was assessed using hematoxylin and eosin (H-E) staining at 7 days after the cold injury. Compared with the untreated control group, treatment with MMI270 significantly reduced the brain water content in the ipsilateral core and intermediate areas and protected the BBB integrity to EB in the ipsilateral core area. The secondary lesion was significantly smaller in the MMI270-treated animals compared with the untreated animals. Our results indicate that treatment with MMI270 in rats exhibits protection in acute brain edema formation and secondary brain lesion by attenuating the BBB permeability after cold injury.
Animals↗
The use of mild hypothermia for patients with severe vasospasm: a preliminary report.
The purpose of this study was to determine the effect of mild hypothermia on cerebral ischaemia due to severe vasospasm, which was refractory to medical and intravascular treatments and to assess the brain protection of this treatment in patients who underwent delayed aneurysm clipping after presenting with ischaemic neurological deficits. Mild hypothermia (32-34 degrees C of brain temperature) was employed in two groups: (1) Patients (Hunt and Kosnik grades I to II) who showed progressive neurological deficits due to vasospasm and did not respond to conventional therapy (Group 1) and (2) Patients who received delayed aneurysm clipping after presenting with ischaemic neurological deficits due to vasospasm (Group 2). Seven of 8 patients in both Groups showed a favorable outcome with mild hypothermia (good recovery in 5 and moderate disability in two patients). Mild hypothermia is considered to be effective on critical cerebral ischaemia due to vasospasm even after failure to response the conventional therapies and to provide brain protection in delayed aneurysm clipping.
Body Temperature↗
Review article: inflammation-related promotion of gastrointestinal carcinogenesis--a perigenetic pathway.
Chronic inflammation has been reported to accelerate neoplasmas in gastrointestinal tract. Certain bacteria including Helicobacter pylori directly interact with host cells, induce proinflammatory cytokines and stimulate production of free radicals. Free radicals cause mutations in target cells so that neoplastic clones are established. Accumulation of such genetic alterations may cause malignant transformation of some established clones. In addition, inflammatory alterations may promote growth, expansion and invasion of gastrointestinal epithelial cells. The latter changes caused by inflammation may occur even without further genetic mutations or epigenetic alterations, and therefore may be categorized as 'perigenetic alterations' of neoplastic cells. For an example, tumour necrosis factor alpha (TNF-alpha) plays pivotal roles not only in the reduction but also in the growth, invasion and metastases of certain neoplasmas. Our studies show that TNF-alpha increases intracellular radical production, degradates E-cadherin / beta-catenin complex and promotes dispersion and migration in epithelial cells transformed with an activated src oncogene (v-src). These data indicate that an inflammatory cytokine induces the malignant potential of src-activated neoplastic cells. Interestingly, TNF-alpha also induced these phenotypic changes in nonmutated cells whose c-Src was activated by TGF-alpha, suggesting that the invasive properties of the cell were not necessarily related to gene mutation. Furthermore, certain radical scavengers suppressed the invasive phenotype of the cells. These results indicate that perigenetic alterations are an important target of pharmacological intervention of carcinogenesis.
Cell Communication↗
Dynamic shear properties of the temporomandibular joint disc.
Shear stress might be an important factor associated with fatigue failure and damage of the temporomandibular joint disc. Little information, however, is available on the dynamic behavior of the disc in shear. Since the disc is an anisotropic and viscoelastic structure, in the present study the dependency of the dynamic shear behavior on the direction and frequency of loading was examined. Ten porcine discs were used for dynamic shear tests. Shear stress was applied in both anteroposterior (A-P test) and mediolateral (M-L test) directions. The dynamic moduli increased as the loading frequency increased. The dynamic elasticity was significantly larger in the A-P test than in the M-L test, although the dynamic viscosity was similar in both tests. The present results suggest that non-linearities, compression/shear coupling, and intrinsic viscoelasticity affect the shear material behavior of the disc, which might have important implications for the transmission of load in the temporomandibular joint.
Animals↗
Serum thymidine kinase and soluble interleukin-2 receptor predict recurrence of malignant lymphoma.
Before and after therapy, serum thymidine kinase (TK) and soluble interleukin-2 receptor (sIL-2R) were serially determined in 28 patients with malignant lymphoma (ML). In 15 patients achieving and maintaining complete remission (CR) for more than 2 years, serum TK and sIL-2R were unchanged or decreased gradually. In contrast, logarithmic linear increases of TK and sIL-2R were observed in 13 relapsed patients. The increments of the serum markers occurred more than 10 months before the relapse. A significant positive correlation between the slope of the line for TK and that for sIL-2R was noted. The doubling time for TK estimated from the slope also showed a positive correlation with that for sIL-2R. Taken together, serum TK and sIL-2R were shown to be quite sensitive and interrelated serum markers for the recurrence of ML. Slopes of logarithmic linear increase, which are proper and specific for the individual patients, are inversely correlated with the doubling time and reflect proliferation of ML. We conclude that serum TK and sIL-2R are better predictors of relapse than LDH and the international prognostic index (IPI).
Adult↗
Effects of brain hypothermia on brain edema formation after intracerebral hemorrhage in rats.
Patients with intracerebral hemorrhage (ICH) may deteriorate progressively after the initial ictus because of the brain edema around the hematoma. Recently, thrombin has become known to play an important role in the brain edema formation after ICH. In this study, we examined the effect of brain hypothermia on brain edema formation after hematoma and thrombin injection into the brain in rats and clarified the mechanism of hypothermia on brain damage. Anesthetized Sprague-Dawley rats received an injection of 100 microL of autologous blood or 10 units of bovine thrombin into the basal ganglia. Animals were divided into the normothermic and hypothermic groups, which were housed in a room at 25 degrees C and in a cold room at 5 degrees C respectively, for 24 hours. Brain water content was significantly reduced with hypothermia in the cortex (80.8 vs. 79.7% p < 0.05) after hematoma induction. After thrombin injection, brain water content was also significantly reduced with hypothermia in the basal ganglia (84.5 vs. 82.2%; p < 0.01), accompanied by a significant reduction in blood-brain barrier (BBB) permeability to Evan's blue (29.4 vs. 11.6 ng/g tissue; p < 0.05) and in accumulation of polymorphonuclear leukocytes (3.03 vs. 0.27 U of myeloperoxidase/g tissue; p < 0.01). This study indicates that brain hypothermia significantly reduces brain edema formation after hematoma and thrombin injection into the brain in rats. Inhibition of thrombin-induced BBB breakdown and inflammatory response with hypothermia appear to contribute to brain protection in this model.
Animals↗
The combination of ionizing radiation and expression of a wild type p53 gene via recombinant adenovirus induced a prominent tumour suppressing effect in human oral squamous cell carcinoma.
Human oral squamous cell carcinoma (SCC) cell lines HSC4 and SAS were infected with wild type p53 (wt-p53)-encoding adenovirus (AxCAip53) and subsequently irradiated to investigate the effectiveness of p53 gene therapy in combination with radiation therapy for treating oral SCC. Western blot analysis using anti-p53 monoclonal antibody showed that a large amount of mutant p53 protein was accumulated in HSC4 cells, while no detectable p53 protein was observed in SAS cells. The induction of p53 expression by AxCAip53 infection was clearly observed in both HSC4 and SAS cells. A clonogenic cell survival assay demonstrated that AxCAip53 infection alone, or X-irradiation alone, significantly inhibited the growth of cancer cells, but that combined treatment was most effective, even in mutant p53-accumulated HSC4 cells. Flow cytometric analysis showed that the apoptotic pathway was induced in virus treated and radiation treated cells. Taken together, these findings suggest that the combination of p53 gene therapy and radiation therapy has a possibility to effectively treat oral SCC defective in p53 function.
Adenoviridae↗