Biomedical subjects

K Aoki

Publications and source records attributed to K Aoki.

At least 55 records · Page 3Linked to original sources

PubMed2003

Bone mineral density of the mandible in ovariectomized rats: analyses using dual energy X-ray absorptiometry and peripheral quantitative computed tomography.

INTRODUCTION: Although previous studies have shown that maxillary molar extraction in ovariectomized (OVX) animals causes mandibular loss of bone, it is still questionable as to whether estrogen deficiency affects mandibles with functional occlusion. MATERIALS AND METHODS: To answer this question, 13-week-old female Sprague-Dawley rats were bilaterally OVX or sham-operated. After 109 days, the bone mineral density (BMD) of the femurs and mandibles was measured using dual-energy X-ray absorptiometry (DEXA) and peripheral quantitative computed tomography (pQCT). RESULTS: In DEXA analysis, although the BMD of the total mandible of the OVX rats was similar to that of the sham-operated rats, the BMD of the condylar region in the OVX rats had decreased by 12.5%. In pQCT analysis, decrease in trabecular BMD of the mandibular bone was detectable but low in the molar region (maximal 13%), whereas no difference was seen in cortical BMD. In the femurs, the trabecular bone prominently decreased in OVX rats (30% decrease in pQCT analysis) as previously reported. CONCLUSION: This study revealed regional differences in the mandibular bone decrease in OVX rats. Although the mechanism of low susceptibility of the mandible to estrogen-deficient conditions remains unknown, it is likely that mechanical stress derived from functional occlusion is preventing bone loss in this pathological condition. Furthermore, this study demonstrated the advantage of pQCT in analyzing rat mandibular bone.

Absorptiometry, Photon↗

PubMed2003

Male predominance among Japanese adult patients with late-onset hemorrhagic cystitis after hematopoietic stem cell transplantation.

Late-onset hemorrhagic cystitis (LHC) after hematopoietic stem cell transplantation (HSCT) is mainly caused by viral infections. We retrospectively analyzed the records of 141 Japanese adult patients who underwent a first allogeneic HSCT from 1995 to 2002. In all, 19 patients developed LHC a median of 51 days after HSCT. Adenovirus (AdV) was detected in the urine of 10 LHC patients, of whom eight had AdV type 11. Five of the six available serum samples from these patients were also positive for AdV type 11, but the detection of AdV in serum was not associated with a worse outcome. Male sex and the development of grade II-IV acute graft-versus-host disease were identified as independent significant risk factors for LHC. Male predominance was detected in LHC after HSCT, as has been previously shown in children with AdV-induced acute HC. The detection of AdV DNA in serum did not predict a poor outcome.

Adenoviridae Infections↗

PubMed2003

Adenovirus-mediated gene transfer of interferon alpha improves dimethylnitrosamine-induced liver cirrhosis in rat model.

Several lines of evidence suggest that interferon (IFN)-alpha is effective in suppression of liver cirrhosis (LC) as well as hepatitis C virus (HCV) infection, which is a major cause of LC in Japan. However, IFN-alpha often causes systemic toxicity such as flu-like symptoms, which precludes the IFN-alpha dose escalation required for clinical efficacy. Since IFN-alpha is rapidly degraded in the blood circulation, only a small amount of subcutaneously injected IFN-alpha protein can reach the target organ, the liver. It is expected that on-site IFN-alpha production in the liver overcomes the limitation of the conventional parenteral IFN-alpha administration. An adenovirus vector expressing the rat IFN-alpha gene (AxCA-rIFN) was injected intravenously into rats with dimethylnitrosamine-induced LC. While the subcutaneous IFN-alpha protein injection led to a transient elevation of the cytokine both in the liver and serum, the vector-mediated IFN-alpha gene transduction induced a significant amount of IFN-alpha detected in the liver but not in the serum. The injection of AxCA-rIFN prevented the progression of the rat LC, and improved the survival rate of the treated rats. Although no significant toxicity was noted in the animals, we showed that IFN-alpha gene expression in the liver can be efficiently downregulated by the Cre/loxP-mediated shut-off system, in case the IFN-alpha overdose becomes a problem. The study suggested for the first time the advantage and feasibility of IFN-alpha gene therapy for LC.

Adenoviridae↗

PubMed2003

Effect of milrinone on vecuronium-induced neuromuscular block.

We examined the effect of milrinone, a phosphodiesterase III inhibitor, on neuromuscular block induced by vecuronium. Thirty adult patients were randomly assigned to one of two equal groups: the milrinone group and the control group. Subjects in the milrinone group received an intravenous loading dose of milrinone 5 microg x kg-1x min-1 for 10 min, followed by an infusion at a rate of 0.5 microg x kg-1x min-1. Subjects in the control group received normal saline at a rate of 0.1 ml x kg-1 x h-1. Thirty minutes after the beginning of the infusion of milrinone, anaesthesia was induced with intravenous thiopental 4 mg x kg-1 and fentanyl 2 microg x kg-1, and was maintained with isoflurane in oxygen and nitrous oxide. Neuromuscular blockade was monitored electromyographically at the adductor pollicis muscle. The times from the administration of vecuronium 0.1 mg.kg-1 to the onset of neuromuscular block and the return of the first, second, third, and fourth response of the train-of-four were compared between the two groups. Times to the recovery of the ratio of the first twitch to the control twitch to 25%, 50% and 75%, and times to the recovery of train-of-four ratio to 25%, 50% and 75% were also compared between the two groups. The onset of neuromuscular block in the milrinone group was significantly slower than in the control group. The times to the returns of the four twitches of the train-of-four, times to recovery of the ratio of the first twitch to the control twitch to 25% and 50%, and the times to the recovery of the train-of-four ratio to 25% and 50% were significantly shorter in the milrinone group than in the control group. We conclude that milrinone delays the onset of neuromuscular blockade but hastens its recovery in anaesthetised patients receiving vecuronium.

Adult↗

PubMed2003

Leiomyosarcoma of the kidney in a dog.

A leiomyosarcoma that occurred in the right kidney of a dog (7-year-old female Labrador retriever) was studied pathologically. On histological examination, tumour cells were spindle-shaped, the cell density was high, and complex fasciculated tumour cells showing longitudinal and transverse cross-sections were observed. Both ends of the nuclei were rounded, the nucleoli were clear and many images of nuclear division were observed. Immunohistochemically, tumour cells reacted intensely with anti-vimentin antibody and anti-actin smooth muscle antibody, and mildly with anti-desmin antibody. On electron microscopy, the nuclei of tumour cells were rounded at both ends and elongated elliptically, and a large number of microfibrils with focal density and dense patches were observed in the cytoplasm. This is a case report of a very rare leiomyosarcoma of the dog kidney.

Animals↗

PubMed2003

A new method using a bacterium for dissolution of urinary stones.

PURPOSE: A bacterium, Thiobacillus thiooxidans, oxidizes inorganic sulfur compounds to sulfuric acid to obtain energy for growth. We examined dissolution of urinary stones by the bacteria and studied optimal conditions for the dissolution in human urine. METHODS: Thiobacillus thiooxidans (IFO No. 13 701) was purchased from Hakko Kenkyujyo, Co., Osaka, Japan. The bacteria were grown stationary for 7 days at 30 degrees C in medium. The pH of the medium was changed from pH 4.82 to 1.95 for 28 days. Growth of the bacteria was also examined in human urine by addition of different amounts of sodium thiosulfite. The dissolution of human urinary stones was examined in the bladder of Wistar rat containing the bacteria (1 x 10(8)) for 7 days. 20 ml of 5 % sodium thiosulfite were injected intraperitoneally once a day. Histological changes of urinary tracts and blood test were also examined. As a control, two rats were examined in the same methods without the bacteria. RESULTS: The number of bacteria was increased in human urine depending on the concentration of sodium thiosulfite. Among different kinds of urinary stones, calcium phosphate stone was most dissolved, 78 % reduction of dry weight in the rat bladder. Calcium oxalate, uric acid and magnesium phosphate stones were not well dissolved. But the stone weights in the control rats were increased twice. Slight inflammation was found in the rat bladder. There were no abnormal findings in the blood test. CONCLUSIONS: Thiobacillus thiooxidans can be used for dissolution of urinary stones. This new technique may be useful for dissolution of fragments after ESWL and crystals covered by a urinary stent. Optimal conditions and safety methods should be developed for clinical use.

Acidithiobacillus thiooxidans↗

PubMed2003

Decrease of T-helper 2 and T-cytotoxic 2 cells at implantation sites occurs in unexplained recurrent spontaneous abortion with normal chromosomal content.

BACKGROUND: In normal pregnancy, predominant type 2 cytokines help maintain pregnancy, and a T-helper (Th)1 type response is associated with unexplained recurrent spontaneous abortion (RSA). However, Th2 and T-cytotoxic (Tc)2 cells have not been localized at the implantation site in RSA. METHODS: Twenty-one cases with RSA were classified into RSA with normal chromosomal content (RSA-N, n = 10) and RSA with abnormal chromosomal content (RSA-A, n = 11). As a control, we selected 15 gestational age-matched cases of induced abortion with no history of spontaneous abortion. We immunostained paraffin-embedded decidual sections for a specific Th2 and Tc2 cell marker termed 'chemo-attractant receptor-homologous molecule expressed on Th2 cells (CRTH2)' and T-cell markers CD3 and CD8. The numbers and percentages of Th2 (CRTH2(+)CD8(-)CD3(+)) and Tc2 (CRTH2(+)CD8(+)) cells were compared between the decidua basalis and decidua parietalis. RESULTS: Th2 and Tc2 cells accumulated in the decidua basalis in normal pregnancy. Accumulation of Tc2 cells and both Th2 and Tc2 cells decreased in the decidua basalis in RSA-A and RSA-N respectively. The number and percentage of Th2, and Tc2 cells in the decidua parietalis were similar in normal pregnancy, RSA-A and RSA-N. CONCLUSION: Decreased Th2 and Tc2 cells at the implantation site may contribute to RSA-N.

Abortion, Habitual↗

PubMed2003

Long-term treatment with sterigmatocystin, a fungus toxin, enhances the development of intestinal metaplasia of gastric mucosa in Helicobacter pylori-infected Mongolian gerbils.

BACKGROUND: Helicobacter pylori is a human gastric carcinogen. Sterigmatocystin (ST), a fungus toxin, is a risk factor of gastric cancer. Cytotoxin-vacuolation toxin A (VacA) present in supernatants of H. pylori suspensions can cause gastritis and ulcer. The aim of this study was to examine the effects of H. pylori, ST and VacA in Mongolian gerbils. METHODS: Male Mongolian gerbils (n = 196) were treated with H. pylori supernatants (10 ml/1000 mg) mixed with diet or inoculated intragastrically with H. pylori alone or with ST (100 or 1000 ppb), and then killed 27 months later. Gastric tissue sections were stained with haematoxylin and eosin (H&E), periodic acid-Schiff (PAS), Alcian blue (AB, pH 2.5) and with immunostaining for PCNA and p53 expression. RESULTS: In H. pylori-infected gerbils, the normal mucosa was replaced by hyperplastic epithelium. Severe gastritis, cystic dilatation of gastric glands, hyperplastic polyps and intestinal metaplasia were observed. In H. pylori + ST (1000 ppb) gerbils, intestinal metaplasia was significantly more frequent than in H. pylori alone animals. No pathological changes were observed in the H. pylori supernatant group. Osseous metaplasia was observed in the H. pylori + ST (100 ppb) group. Serum gastrin levels of the H. pylori + ST (1000 ppb) group were significantly higher than those of the other groups. PCNA labelling index and p53 index of infected gerbils were significantly higher than those of uninfected groups. CONCLUSION: H. pylori causes gastritis, ulcer and intestinal metaplasia. ST enhances the development of intestinal metaplasia and increases gastrin levels in H. pylori-infected Mongolian gerbils.

Animals↗

PubMed2002

Sigma-nucleus potential in A=28.

We have studied the (pi(-),K+) reaction on a silicon target to investigate the sigma-nucleus potential. The inclusive spectrum was measured at a beam momentum of 1.2 GeV/c with an energy resolution of 3.3 MeV (FWHM) by employing the superconducting kaon spectrometer system. The spectrum was compared with theoretical calculations within the framework of the distorted-wave impulse approximation, which demonstrates that a strongly repulsive sigma-nucleus potential with a nonzero size of the imaginary part reproduces the observed spectrum.

Journal Article↗

PubMed2002

Role of MAPK in chronic cerebral vasospasm.

This study was undertaken to investigate the role of p44/42 MAPK in a dog double hemorrhage model of subarachnoid hemorrhage (SAH), and whether MEK inhibitors can alter the degree of SAH-induced vasoconstriction. The diameter of the basilar artery, which was compared with day 0 angiogram, decreased gradually in a time-dependent manner from day 3 (80%), day 5 (68%) through day 7 (53.5%). The level of MAPK (p44/42) immunoprecipitation peaked on day 3 and remained enhanced through day 7 (P < 0.05). MEK inhibitor PD98059 significantly reduced p44/42 MAPK immunoprecipitation and significantly reversed vasospasm and increased residual diameter to 79.0% on day 7. These results demonstrated that p44/42 MAPK kinase is involved in the pathogenesis of cerebral vasospasm. The MEK inhibitor PD98059 might be useful in the treatment of vasospasm.

Animals↗

PubMed2002

Protonic diffusion in high-pressure ice VII.

Near ambient pressures, molecular diffusion dominates protonic diffusion in ice. Theoretical studies have predicted that protonic diffusion will dominate at high pressures in ice. We measured the protonic diffusion coefficient for the highest temperature molecular phase of ice VII at 400 kelvin over its entire stable pressure region. The values ranged from 10(-17) to 10(-15) square meters per second at pressures of 10 to 63 gigapascals. The diffusion coefficients extrapolated to high temperatures close to the ice VII melting curve were less by a factor of 10(2) to 10(3) than a superionic criterion of approximately 10(-8) square meters per second, at which protons would diffuse freely.

Journal Article↗

PubMed2002

Proton energy spectra in the nonmesonic weak decay of 12lambdaC and 28lambdaSi hypernuclei.

Numbers of protons per Gamma hypernuclear weak decay were measured as a function of proton energy above 40 MeV, explicitly identifying production of Gamma hypernuclei by the (pi+,K+) reaction. The ratios between the neutron-stimulated to proton-stimulated nonmesonic decay widths, Gamma((Lambda)n-->nn)/Gamma((Lambda)p-->np) ( = Gamma(n)/Gamma(p)) were extracted by fitting the proton energy spectra. The present result claims that the proton yields are suppressed and the Gamma(n)/Gamma(p) ratios are close to 1 both for 12LambdaC and 28LambdaSi in contradiction to theoretical expectations based on meson exchange models.

Journal Article↗

PubMed2002

Metabolic alterations in cerebrospinal fluid from double hemorrhage model of dogs.

OBJECTIVE: Even though cerebral vasospasm after subarachnoid hemorrhage (SAH) causes cerebral ischemia or infarction, the metabolic alterations in cerebrospinal fluids (CSF) after SAH have not been studied. This study was undertaken to measure the levels of glucose, lactate, pyruvate and glutamate in CSF from double hemorrhage dog models. METHOD: Thirty-two mongrel dogs of either sex, weighing 15-30 kg, underwent double hemorrhage by percutaneous needle puncture of the cisterna magna and injection of autologous blood on day 0 and day 2. The dogs were then sacrificed on day 3, 5 and 7, after collecting CSF. In another study, the dogs were treated with mitogen-activated protein kinase (MAPK) inhibitors PD98059 and U0126, and caspase-2 and caspase-3 inhibitors from day 3 to day 6 after initial blood injection. CSF was collected on day 7 before dogs were sacrificed. The concentration of glucose, lactate, pyruvate and glutamate in CSF was measured by photometrical method. RESULTS: Compared with CSF collected on day 0, glucose was decreased on days 5-7, lactate was increased on days 2-7, pyruvate was increased on days 2-7, and glutamate was increased on days 3-7 (P < 0.05). In the groups treated with MAPK or caspase inhibitors, most of the metabolic alterations remained unchanged as compared with CSF from untreated dogs. Clinically, caspase inhibitors-2 and -3, and MAPK inhibitor U0126 all failed to prevent vasospasm. MAPK inhibitor PD98059 partially prevented vasospasm. CONCLUSION: Our data demonstrated a metabolic alteration of glucose, glutamate, lactate and pyruvate in CSF during cerebral vasospasm. This metabolic change is consistent with the time course of cerebral vasospasm. This study suggests that brain energy metabolites and excitative amino acids are altered during cerebral vasospasm.

Analysis of Variance↗

PubMed2002

Monitoring of cytomegalovirus reactivation after allogeneic stem cell transplantation: comparison of an antigenemia assay and quantitative real-time polymerase chain reaction.

Cytomegalovirus (CMV) antigenemia and quantitative real-time polymerase chain reaction (PCR) were compared for monitoring of CMV reactivation after allogeneic stem cell transplantation. The number of CMV antigen-positive cells by the antigenemia assay and the level of CMV DNA by real-time PCR correlated well. The sensitivity and specificity of the antigenemia assay was 55.4% and 95.5%, respectively, using real-time PCR as the reference standard. The probability of positive antigenemia at day 100 was 76.5%, with a median of first detection at day 37 in 51 patients, compared with a positive PCR of 84.3% and day 33, respectively. When HLA-identical sibling donor transplant recipients and other donor transplant recipients were analyzed separately, there was no difference between the two tests. However, temporal patterns of first detection of CMV antigen-positive cells and CMV DNA differed between HLA-identical and alternative recipients; patients without CMV (29%) or with sporadic positive PCR results (14%) were more common in HLA-identical sibling transplants, whereas patients with simultaneous antigenemia and positive PCR occurred more in alternative transplants (48%). Two of 51 patients (4%) developed CMV colitis despite antigenemia-guided prophylaxis, but both were successfully treated with ganciclovir. Although PCR is more sensitive than antigenemia, both tests are useful in the early detection of CMV after allogeneic stem cell transplantation.

Adolescent↗

PubMed2002

Stomach cancer-related mortality rate is higher in young Japanese women than in men.

This study compares stomach cancer-related mortality rates in Japan with those in European and Asian countries and analyzes trends in stomach cancer-related mortality rates according to gender in young Japanese over the period of 1957-1997. From official death certification numbers and population estimates, we obtained stomach cancer-related mortality rate for all ages and various ages according to gender. Japan's ranking compared to other countries in death percentage of all cancers which are attributable to stomach cancer was fourth for both men and women. In Japan and Ireland, total elimination of deaths from stomach cancer in men resulted in increased life expectancy of 0.68 and 0.22 y respectively, whereas the corresponding figures for women were 0.42 and 0.14 y respectively. The sex ratios of stomach cancer-related mortality rates were 0.75, 0.63, 0.80 and 0.94 for 25-29, 30-34, 35-39 and 40-44 y age groups, respectively, in 1997. The sex ratio of relative risk ranged from 0.62 to 0.92 in 25-40 y age groups during the observation period. The life expectancy in 30-34 y age group increased by 0.66 y for men and 0.41 y for women in 1995 after elimination of stomach cancer-related deaths. Our results suggest that stomach cancer-related mortality rates are still high in Japan and young women are at higher risk of stomach cancer-related death relative to young men and that sex ratio is stable or slightly decreased over the 40-y period. It is important to monitor this trend continuously in the next few years.

Adult↗

PubMed2002

Sweating response in physically trained men to sustained handgrip exercise in mildly hyperthermic conditions.

To investigate the effects of physical training on heat loss response to sustained handgrip exercise (non-thermal factors), we compared the sweating response during isometric handgrip exercise to mild hyperthermia in physically trained and untrained subjects. Seven trained and untrained male subjects (maximal oxygen uptake 62.7 +/- 2.4 and 42.7 +/- 1.6 mL kg-1 min-1, respectively, P < 0.05) performed isometric handgrip exercises at 20, 35 and 50% maximal voluntary contraction (MVC) for 60 s. The study was conducted in a climatic chamber with a regulated ambient temperature of 35 degrees C and relative humidity of 50% to induce sweating response at rest by rising skin temperature without a marked change in internal temperature. Sublingual and mean skin temperatures (thermal factors) in both trained and untrained groups were essentially constant throughout all exercise intensities. Changes in heart rate, mean arterial blood pressure, and rating of perceived exertion with increased exercise intensity were similar in both groups. Sweating rate (SR) on the limbs (mean value of forearm and thigh) was significantly greater in the trained group than in the untrained group at 50% MVC (P < 0.05). In addition, the slopes of the relationship between increased SR and exercise intensity (% MVC) on the trunk (chest) and limbs were significantly greater in the trained group than in the untrained group (P < 0.05). Our results suggest that the sweating response caused by non-thermal factors against a background of changing thermal factors was enhanced by physical training. It is also thought that the enhanced sweating response may be especially evident on the limbs than on the trunk, such as improvement of sweating response associated with thermal factors.

Adult↗

PubMed2002

Sweating responses to a sustained static exercise is dependent on thermal load in humans.

The purpose of this project was to test the hypothesis that internal temperature modulates the sweating response to sustained handgrip exercise. Ten healthy male subjects immersed their legs in 43 degrees C water for 30-40 min at an ambient temperatures of 30 degrees C and a relative humidity of 50%. Sweating responses to 50% maximal voluntary contraction isometric handgrip exercise (IH) were measured following the onset of sweating (i.e. following slight increases in internal temperature), and after more pronounced increases in internal temperature. Oesophageal temperature (Tes) was significantly lower during the first bout of exercise (37.54 +/- 0.07 degrees C) relative to the second bout (37.84 +/- 0.12 degrees C; P < 0.05). However, the increase in mean sweating rate (SR) from both the chest and forearm (non-glabrous skin) was significantly greater during the first IH bout relative to the second bout (P < 0.05). Increases in mean arterial blood pressure and palm SR (glabrous skin) did not differ significantly between exercise bouts, while heart rate and rating of perceived effort were significantly greater during the second bout of IH. As Tes and mean skin temperature did not change during either bout of exercise, the changes in SR from non-glabrous skin between the bouts of IH were likely because of non-thermal factors. These data suggest that sweating responses from non-glabrous skin during IH vary depending on the magnitude of thermal input as indicated by differing internal temperatures between bouts of IH. Moreover, these data suggest that the contribution of non-thermal factors in governing sweating from non-glabrous skin may be greatest when internal temperature is moderate (37.54 degrees C), but has less of an effect after greater elevations in internal temperature (i.e. 37.84 degrees C).

Adult↗

PubMed2002

Experimental validation of a combined electromagnetic and thermal model for a microwave drying of capillary porous materials inside a rectangular wave guide (effects of irradiation time, particle sizes and initial moisture content).

In this paper, the experimental validation of a combined electromagnetic and thermal model for a microwave drying of capillary porous materials inside a rectangular wave guide is presented. The effects of the irradiation time, particle sizes and the variation of initial moisture content on the microwave drying kinetics are clarified in detail, considering the interference between incident and reflected waves in the capillary porous materials. The established model has allowed us to determine the space-time evolution of electric field, temperature and moisture content within capillary porous materials during microwave drying process.

Journal Article↗