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Biomedical subjects

M Nakamura

Publications and source records attributed to M Nakamura.

At least 145 records · Page 8Linked to original sources
PubMed2003

Androgen and the blocking of radiation-induced sensitization to Fas-mediated apoptosis through c-jun induction in prostate cancer cells.

PURPOSE: To clarify the key mechanism by which androgen makes prostate cancer cells highly resistant to Fas-mediated apoptosis. MATERIALS AND METHODS: The role of c-jun induction by 10 nM dihydrotestosterone (DHT) in 5 Gy radiation-induced up-regulation of Fas and sensitization to the apoptosis was studied by using the human prostate cancer cell line LNCaP. RESULTS: On exposure to 5 Gy radiation, LNCaP cells demonstrated high sensitization to Fas-mediated apoptosis through increased Fas expression, stabilized p53 expression and binding to p53 response elements within the promoter and first intronic region of the Fas gene. Following treatment with DHT, in vivo binding of p53 to its response elements was strongly inhibited. In addition, DHT significantly up-regulated c-jun expression through extracellular stress-regulated kinase (ERK) activation, and transfection of an antisense oligonucleotide for c-jun or ERK inhibition by PD98059 cancelled DHT-mediated suppression of radiation-induced transactivation of Fas gene and sensitization to Fas-mediated apoptosis. CONCLUSIONS: Radiation-induced Fas sensitization in prostate cancer cell was mediated through p53-dependent transactivation of the Fas gene, which can be blocked by androgen stimulation mainly through induction of c-jun.

Androgens↗
PubMed2003

Warming by resistive heating maintains perioperative normothermia as well as forced air heating.

BACKGROUND: Even mild perioperative hypothermia is associated with several severe adverse effects. Resistive heating has possible advantages compared with other active warming systems because it can heat several fields independently. To assess this new warming system, we measured core temperature in patients during surgery who were warmed with circulating water mattresses, forced air covers or resistive heating covers. METHODS: Twenty-four patients undergoing laparoscopic cholecystectomy were randomly assigned to (i) circulating water mattress (38 degrees C), (ii) forced air warming (set to 'medium') or (iii) carbon-fibre resistive warming (38 degrees C). Warming was applied throughout anaesthesia and surgery. The groups were compared using one-way ANOVA and Student-Newman-Keuls tests. RESULTS: Confounding factors were similar among the groups. Core temperatures in each group decreased for 20 min, but subsequently increased in the forced air and resistive heating groups. There was no significant difference between the forced air and resistive heating groups at any time. In contrast, core temperature in the circulating water group continued to decrease. Consequently, core temperature in the circulating water group was significantly lower than in the other groups 30 min after anaesthetic induction and at later times. CONCLUSIONS: Resistive heating maintains core body temperature as well as forced air heating and both are better than circulating water. Resistive heating offers the advantage of adjustable heating pods.

Adult↗
PubMed2003

Expression of Dmrt1 protein in developing and in sex-reversed gonads of amphibians.

Many genes are known to be involved in gonadal differentiation in vertebrates. Dmrt1, a gene that encodes a transcription factor with a DM-domain, is considered to be one of the essential genes controlling testicular differentiation in mammals, birds, reptiles, amphibians and fish. However, it still remains unknown which testicular cells of animals other than mice and chicks express Dmrt1 protein. For an explanation of its role(s) in testicular differentiation in vertebrates, the expression of the Dmrt1 protein needs to be studied. For this purpose, we conducted an immunohistochemical study of this protein in an amphibian by using an antibody specific for Dmrt1. No positive signal was found in the indifferent gonad of tadpoles of Rana rugosa at early stages. However, in the testis of tadpoles at later stages (XV-XXV) and in frogs one month after metamorphosis, this protein was expressed in interstitial cells and Sertoli cells. In the testis of adult frogs, germ cells also expressed Dmrt1 protein. RT-PCR analysis revealed that the gene for this protein was not transcribed at any time during ovarian development, but was expressed in the female to male sex-reversed gonad. This was true when immunohistological studies were performed. In addition, Southern blot analysis showed DMRT1 to be an autosomal gene. Taken together, our findings indicate that Dmrt1 protein is expressed by interstitial cells, Seroli cells and germ cells in the testis of R. rugosa. Dmrt1 may thus be very involved in the testicular differentiation of amphibians.

Animals↗
PubMed2003

Evaluation of static bone cavities with CT and MRI.

OBJECTIVES: To determine by CT and MRI the contents of static bone cavities (SBCs), which are thought to be formed by aberration of the submandibular gland. METHODS: Non-contrast-enhanced and contrast-enhanced CT was performed on 12 subjects (10 male and 2 female; age 18-64 years; mean age 57 years) in whom SBCs had been discovered incidentally on panoramic radiographs during routine dental treatment. MRI was also performed on 3 of the 12 subjects. RESULTS: No submandibular gland tissue was seen in the SBCs in any of the cases. However, fatty tissue of low attenuation was found in the SBCs in all cases on CT images. Blood vessels were seen in the SBCs in 10 cases, and enhanced soft tissue in contact with the bone cavity wall was seen in the SBCs in 2 cases. Blood vessels in the SBCs were observed on MR images in all three cases. Dilatation of the cavity blood vessels was seen in all 10 cases. Slight tortuosity of the blood vessels was seen in 4 of the 10 cases. CONCLUSIONS: Examination of contrast-enhanced CT images and MR images revealed that the contents of SBCs were not aberrations of the submandibular gland, as has generally been thought, but fatty tissue, blood vessels and soft tissue.

Adipose Tissue↗
PubMed2003

Epidemiological characteristics of acute pulmonary thromboembolism in Japan.

AIM: In Japan, acute pulmonary thromboembolism (APTE) is still rare, but the number of patients with APTE has been steadily increasing. It is important for early diagnosis and early management of APTE to recognize epidemiological characteristics of this condition. METHODS: We investigated the epidemiological characteristics of 252 patients with APTE who were admitted to our institutions between 1975 and 2001. APTE was more prevalent in women that in men. It was observed the most in the age group between 50s to 70s, especially in women. Many patients had prolonged immobilization, recent major operation, obesity, or cancer, as risk factors for venous thromboembolism. One hundred and thirty-eight patients developed APTE in hospital; 60 patients were in Department of Internal Medicine, 28 in General Surgery, 15 in Orthopedics, 15 in Obstetrics and Gynecology, and 20 in other services. RESULTS: Among 58 patients with malignancy, 43% had cancers in digestive organs, 21% in gynecological, and 17% in urological. Among 61 patients who were examined for the presence of thrombophilia, 13 patients had inherited thrombophilia (8 protein C deficiency, 4 protein S deficiency, and 1 antithrombin III deficiency) 11 had antiphospholipid antibodies which indicated thrombophilia. Five out of the above 61 patients (8%) had no obvious risk factors including thrombophilia. CONCLUSION: The findings in our patients were almost the same as those in Western patients, except for some points. These results might be useful to establish a preventive approach for APTE in Japan.

Acute Disease↗
PubMed2003

Secondary infections with beta-hemolytic streptococci in skin lesions.

Secondary infections (SI) in skin lesions are common. In the present study 40 beta-hemolytic streptococci were isolated from 36 patients suffering from SI due to various skin diseases. Staphylococcus aureus coexisted with beta-hemolytic streptococci in 29 of these cases (81%), and beta-hemolytic streptococci were often associated with coagulase-negative staphylococci and gram-positive rods. Eighteen patients (50%) carried beta-hemolytic streptococci predominantly. In most cases of SI due to atopic dermatitis (AD), the predominant species was S. aureus, while in other skin diseases, S. aureus and beta-haemolytica streptococci were predominant in approximately 50% of the patients, except for SI due to tumors and viral diseases. The mean age of patients with SI and beta-hemolytic streptococci was 37 years and that of patients with SI and predominant S. aureus was 32 years. The lower mean age found for S. aureus was due to SI found in patients with AD. This study emphasizes the polymicrobial microbiology of SI.

Adolescent↗
PubMed2003

[A survey on the dioxin level in breast milk in coastal and inland region].

OBJECTIVE: To study the dioxin level of breast milk among Chinese mothers, and to assess the dioxin intake of new-born babies from mother's milk and compare with the Tolerable Daily Intake (TDI) of dioxin. METHODS: The CALUX bioassay was used to detect the dioxin concentration of the first time mother's milk among the inland samples (Shenyang region; 32 cases) and the coastal city samples (Dalian region; 47 cases). RESULTS: The median value of the dioxin Toxic Equivalence (TEQ) in breast milk in the Dalian region was 15.84 pg TEQs.g(-1) fat, which was significantly higher than that in the Shenyang region 7.21 pg TEQs.g(-1) fat (P < 0.01). CONCLUSION: The dioxin level in breast milk in Chinese is at the world's average level. The dioxin intake of the new-born babies during the period of lactation was higher than the lowest limit of the Tolerable Daily Intake (TDI) proposed by WHO. This situation should be noticed by the related authorities.

China↗
PubMed2003

Bound thrombin-induced upregulation of myosin heavy chain isoform, SMemb messenger RNA expression in cultured rabbit vascular smooth muscle cells.

To investigate whether bound thrombin can induce modulation of SMemb expression in vascular smooth muscle (VSM) cells, messenger RNA (mRNA) expression was measured by in situ hybridization (ISH) and reverse transcription-polymerase chain reaction (RT-PCR) in cultured rabbit aortic VSM cells. To test the concentration- and time-dependent effect of bound thrombin on the expression of SMemb, confluent VSM cells were incubated for 48 h in 10% FBS-DMEM containing 0, 3, 10 and 30 units/ml of bound thrombin. In addition, the confluent VSM cells were incubated for 6, 12, 24 and 48 h in 10% FBS-DMEM containing 10 units/ml of bound thrombin. Consequently, bound thrombin significantly increased SMemb mRNA in a concentration- and time-dependent manner. When compared with the effect of rabbit fibrinogen (10 microg/ml) and native thrombin (10 units/ml), SMemb mRNA was significantly increased by bound thrombin and was slightly increased by native thrombin, but not by fibrinogen. Other myosin heavy chain (MHC) isoform (SM1 and SM2) mRNA expressions were not changed by fibrinogen, native thrombin or bound thrombin. ISH revealed that there was no significant difference in the expression of MHC mRNAs among fibrinogen, native thrombin or bound thrombin. Western blot analysis demonstrated that the SMemb protein level was significantly increased by 2.5-fold by bound thrombin. When the clot-forming activities in cultured medium containing native thrombin or bound thrombin were measured from 0.5 to 48 h, the activity of bound thrombin declined more slowly than that of native thrombin. In conclusion, bound thrombin could upregulate the expression of SMemb mRNA and protein in cultured VSM cells and the activity of bound thrombin was maintained for longer than that of native thrombin in culture medium.

Animals↗
PubMed2002

Primary processes of laser-induced selective dimer-layer removal on Si(001)-(2x1).

Excitation with nanosecond-laser pulses at fluences well below the melt threshold removes Si dimers on the Si(001)-(2x1) surface and induces atomic-Si desorption through an electronic mechanism. The rate of this photoinduced reaction depends superlinearly on the excitation intensity, and is enhanced resonantly at the photon energy where the optical transition injects holes into the dimer backbond surface-band state. The results reveal the crucial role of surface holes and their nonlinear localization in the bond rupture of Si dimers on this surface.

Journal Article↗
PubMed2002

Haemodynamic assessment in patients with dural arteriovenous fistulae: dynamic susceptibility contrast-enhanced MRI.

Cerebral haemodynamics in patients with dural arteriovenous fistulae (DAVF) have not been fully investigated and their effects are not clear. Our purpose was to assess impaired haemodynamics in patients with DAVF using dynamic susceptibility contrast-enhanced MRI (DSC-MRI). We used this technique in eight control subjects (group I) and 17 patients with DAVF who were scheduled to undergo or had already undergone endovascular embolisation and/or surgical excision. There were seven patients with cavernous sinus DAVF (CSDAVF) and the other ten had unilateral transverse/sigmoid sinus DAVF. All patients with CSDAVF underwent DSC-MRI preoperatively (group II) and those with transverse/sigmoid sinus DAVF underwent preoperative DSC-MRI (group III) and postoperative (group IV) assessment. The ratios of relative cerebral blood volume (rCBV), cerebral blood flow (rCBF) and mean transit time (rMTT) were calculated relative to contralateral values. Patients in group II had no significant haemodynamic impairment in grey (GM) or white matter (WM), but cerebellar rMTT were significantly prolonged ( P<0.05). Group III showed haemodynamic impairment characterised by significant increase in rCBV, prolongation of rMTT and decrease in rCBF in GM ( P<0.05). Significantly increased rCBV and prolonged rMTT in the GM ( P<0.05) were obvious in group III patients irrespective of retrograde leptomeningeal venous drainage (RLVD). In group IV, rCBV and rCBF returned to normal values, whereas rMTT was still significantly prolonged in GM ( P<0.05). Our study indicates that patients with CSDAVF may have impaired cerebellar perfusion, and that those with transverse/sigmoid sinus DVAF can have disturbed cerebral haemodynamics, even in the absence of RLVD.

Arteriovenous Fistula↗
PubMed2002

Transplantation of in vitro-expanded fetal neural progenitor cells results in neurogenesis and functional recovery after spinal cord contusion injury in adult rats.

Neural progenitor cells, including neural stem cells, are a potential expandable source of graft material for transplantation aimed at repairing the damaged CNS. Here we present the first evidence that in vitro-expanded fetus-derived neurosphere cells were able to generate neurons in vivo and improve motor function upon transplantation into an adult rat spinal-cord-contusion injury model. As the source of graft material, we used a neural stem cell-enriched population that was derived from rat embryonic spinal cord (E14.5) and expanded in vitro by neurosphere formation. Nine days after contusion injury, these neurosphere cells were transplanted into adult rat spinal cord at the injury site. Histological analysis 5 weeks after the transplantation showed that mitotic neurogenesis occurred from the transplanted donor progenitor cells within the adult rat spinal cord, a nonneurogenic region; that these donor-derived neurons extended their processes into the host tissues; and that the neurites formed synaptic structures. Furthermore, analysis of motor behavior using a skilled reaching task indicated that the treated rats showed functional recovery. These results indicate that in vitro-expanded neurosphere cells derived from the fetal spinal cord are a potential source for transplantable material for treatment of spinal cord injury.

Age Factors↗
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

Measurement of analyzing power for proton-carbon elastic scattering in the coulomb-nuclear interference region with a 22-GeV/c polarized proton beam.

The analyzing power for proton-carbon elastic scattering in the Coulomb-nuclear interference region of momentum transfer, 9.0x10(-3)<-t<4.1x10(-2) (GeV/c)(2), was measured with a 21.7 GeV/c polarized proton beam at the Alternating Gradient Synchrotron of Brookhaven National Laboratory. The ratio of hadronic spin-flip to nonflip amplitude, r(5), was obtained from the analyzing power to be Rer(5)=0.088+/-0.058 and Imr(5)=-0.161+/-0.226.

Journal Article↗
PubMed2002

Changes in activities of enzymes related to energy metabolism in peripheral leukocytes of diabetic dogs with glycemic control by intensive insulin treatment.

Changes in plasma glucose, immunoreactive insulin (IRI), and free fatty acids (FFA) concentrations and activities of enzymes related to energy metabolism in peripheral leukocytes were measured in type 1 diabetic dogs induced by streptozotocin administration before and after intensive insulin treatments. Before the insulin treatment, the plasma glucose concentrations were over 16.7 mmol/L and the activities of enzymes remarkably decreased in leukocytes of the diabetic dogs. In particular, malate dehydrogenase (MDH) activities decreased significantly. After glycemic control was achieved by insulin treatment, the plasma glucose concentrations were maintained between 6.8 and 7.7 mmol/L and the activities of enzymes restored to those in the control dogs. The changes in ML ratio (cytosolic MDH/lactate dehydrogenase specific activity ratio) reflected faithfully to metabolic conditions of animals and were considered to be a useful parameter to evaluate glycemic control and the effect of injected insulin in the diabetic dogs.

Animals↗
PubMed2002

Intraoperative lymphatic mapping and sentinel lymph node biopsy in patients with papillary carcinoma of the thyroid gland.

We examined the feasibility of sentinel lymph node biopsy for thyroid cancer. Thirty-eight patients with papillary thyroid carcinoma underwent intraoperative lymphatic mapping and sentinel lymph node biopsy. At surgery, we exposed the thyroid gland and used a tuberculin syringe to inject 0.2 ml of 1% patent blue dye directly into the thyroid mass. The lymphatics and the lymph node dyed with blue dyes, was excised as a sentinel lymph node. Modified radical neck dissection was performed following sentinel lymph node biopsy and the diagnostic ability of sentinel lymph node biopsy was examined. A sentinel lymph node was identified successfully in 27 (71%) of 38 patients. Sentinel lymph node biopsy removed one to three lymph nodes (median, two nodes). Eighteen patients had paratracheal sentinel lymph nodes, five patients had jugular sentinel lymph nodes, and four patients had both. Histological nodal metastasis was recognized in 16 of 27 cases. The positive rate of cancer metastases in sentinel lymph nodes was 58%, which was significantly higher than 11% in non-sentinel lymph nodes. Diagnostic ability of sentinel lymph node biopsy showed that accuracy was 89%, sensitivity was 84%, and specificity was 100%. Our preliminary study indicated that sentinel lymph node biopsy was available on detection of non-palpable nodal metastasis in the patients with thyroid cancer; however, further experience and refinement are needed.

Adult↗
PubMed2002

Pyrazinamide resistance associated with pncA gene mutation in Mycobacterium tuberculosis in Japan.

Thirty Japanese clinical isolates of Mycobacterium tuberculosis were analysed by pyrazinamide susceptibility testing and pyrazinamidase assay, as well as polymerase chain reaction for single-strand conformational polymorphism and direct sequencing of the gene encoding pyrazinamidase (pncA). All sensitive isolates showed pyrazinamidase activity and a wild-type pncA gene, but three resistant isolates had pncA gene mutations and lacked pyrazinamidase activity. The latter isolates showed a minimum inhibitory concentration of at least 100 mg/l by the 7H10 agar proportion method and 400 mg/l by the 7H9 liquid medium method. Isolate 28 showed T-to-C change at position 11, leading to Leu4 --> Ser substitution; isolate 29 had an 8-bp deletion from position 382; and isolate 30 had A-to-C change at position 29, leading to Gln10 --> Pro substitution. The deletion has not been described previously. This is the first demonstration of pncA gene mutations in PZA-resistant M. tuberculosis strains isolated from Japanese patients.

Amidohydrolases↗