Biomedical subjects

Takashi Koyama

Publications and source records attributed to Takashi Koyama.

At least 19 recordsLinked to original sources

PubMed2007

Staging of carcinoma of the uterine cervix and endometrium.

Carcinoma of the uterine cervix and endometrium are common gynecologic malignancies. Both carcinomas are staged and managed by means of the International Federation of Gynecology and Obstetrics (FIGO) staging system. In uterine cervical cancer, the FIGO staging system is determined preoperatively by limited conventional procedures. Although this system is effective for early stage disease, it has inherent inaccuracies in advanced stage diseases and does not address nodal involvement. CT and MR imaging are widely used as comprehensive imaging modalities to evaluate tumor size and extent, and nodal involvement. MR imaging is an excellent modality for depicting invasive cervical carcinoma and can provide objective measurement of tumor volume, and provides high negative predictive value for parametrial invasion and stage IVA disease. In contrast, endometrial cancer is surgically staged. Beside recognition of the important prognostic factors, including histologic subtype and grade, accurate assessment of the tumor extent on preoperative MR imaging is expected to greatly optimize surgical procedure and therapeutic strategy. Contrast-enhanced MR imaging can offer "one stop" examination for evaluating the depth of myometrial invasion cervical invasion and nodal metastases. Evaluation of myometrial invasion on MR imaging may be an alternative to gross inspection of the uterus during the surgery.

Contrast Media↗

PubMed2007

An abdominal aortic rupture due to seatbelt blunt injury: report of a case.

A 66-year-old man, who was a passenger in a car involved in a low-speed head-on motor vehicle accident, was rushed to our hospital. His abdomen was tender and distended. An enhanced computed tomography scan showed a massive retroperitoneal hematoma, and its three-dimensional imaging revealed an active leak of the contrast medium from the aortic bifurcation. He went into shock, and was immediately transferred to the operating theater. Through a median laparotomy, a ruptured site measuring 5 mm in diameter was found at the aortic bifurcation and it was closed with sutures under a proximal aortic control. The other organs showed no evidence of injury. Because of the remarkable edema of the bowel, mesentery, and retroperitoneum, the abdomen was temporarily closed with a mesh sheet to prevent the occurrence of abdominal compartment syndrome. A delayed closure was then successfully performed 4 days later, and he was discharged with no residual sequelae 17 days after the initial operation.

Abdominal Cavity↗

PubMed2006

Cine MR imaging of uterine peristalsis in patients with endometriosis.

Endometriosis is one of the most important causes of infertility; however the precise mechanism by which it affects female fertility is unclear. The objective of this study was to study the functional aspects of the uterus by evaluating uterine contractility in patients with endometrial cysts of the ovary. The study population was recruited from two institutes and consisted of 26 women (periovulatory (10), luteal (13), and menstrual phase (3); age range: 19-51 years) with untreated endometriosis; the control group consisted of 12 healthy women (age range: 22-41 years). Cine MR imaging obtained by a 1.5T magnet was visually evaluated at 12x faster than real speed, focusing on the presence of uterine peristalsis, the direction and frequency of peristalsis, and the presence of sustained uterine contractions. Uterine peristalsis was identifiable in 3/10, 3/13, and 3/3 of the endometriosis patients in each menstrual cycle, respectively, and in 11/12, 3/12, and 5/12 of their control subjects. Peristaltic detection rate and frequency were significantly less for the endometriosis group than for the controls in the periovulatory phase only (p<0.05). Sustained contractions were recognized in 19/36 control subjects and in 13/26 endometriosis patients, but the difference was not significant. Uterine peristalsis appears to be suppressed during the periovulatory phase in patients with endometriosis, which may have an adverse effect on sperm transport.

Adult↗

PubMed2006

Investigation of uterine peristalsis diurnal variation.

BACKGROUND: In women of reproductive age, wavelike movements of the subendometrial myometrium, which is called uterine peristalsis, is considered to be related with fertility and menstrual problems. This is because the direction and frequency of peristalsis is known to be different among menstrual cycle phases. However, nothing is known as regarding diurnal variations. This study was designed to evaluate for the presence of a diurnal variation in uterine peristalsis. MATERIALS AND METHODS: MR studies were performed on 12 volunteers of reproductive age using a 1.5-T magnet, four times per day (at 0800, 1300, 1800 and 2300 h) during three (periovulatory, luteal and menstrual) phases of one menstrual cycle. Sixty images were obtained by half-Fourier acquisition single-shot turbo spin echo every 2 s and displayed on cine mode. Semiautomated software was utilized to discern the presence of peristaltic waves, as well as peristaltic frequency and direction. The presence of sustained contractions was visually determined. RESULTS: There was no statistically significant difference during the daytime for frequency and direction of uterine peristalsis for all menstrual cycle phases. Nonetheless, peristaltic frequency and direction fluctuated during each cycle. Statistically significant peristaltic suppression was observed in association with sustained contractions during the periovulatory phase. CONCLUSIONS: A diurnal variation was not observed for uterine peristalsis. Sporadic changes in peristaltic frequency were observed and appear to be closely related to sustained uterine contractions.

Adult↗

PubMed2006

Specific and flexible roles of heparan sulfate modifications in Drosophila FGF signaling.

Specific sulfation sequence of heparan sulfate (HS) contributes to the selective interaction between HS and various proteins in vitro. To clarify the in vivo importance of HS fine structures, we characterized the functions of the Drosophila HS 2-O and 6-O sulfotransferase (Hs2st and Hs6st) genes in FGF-mediated tracheal formation. We found that mutations in Hs2st or Hs6st had unexpectedly little effect on tracheal morphogenesis. Structural analysis of mutant HS revealed not only a loss of corresponding sulfation, but also a compensatory increase of sulfation at other positions, which maintains the level of HS total charge. The restricted phenotypes of Hsst mutants are ascribed to this compensation because FGF signaling is strongly disrupted by Hs2st; Hs6st double mutation, or by overexpression of 6-O sulfatase, an extracellular enzyme which removes 6-O sulfate groups without increasing 2-O sulfation. These findings suggest that the overall sulfation level is more important than strictly defined HS fine structures for FGF signaling in some developmental contexts.

Animals↗

PubMed2006

Characterization of Japanese flounder (Paralichthys olivaceus) NK-lysin, an antimicrobial peptide.

The NK-lysin cDNA of Japanese flounder, Paralichthys olivaceus, consists of 657bp, containing an open reading frame (ORF) of 444bp, which encodes 147 amino acid residues. The amino acid sequence of Japanese flounder NK-lysin has 21% identity to porcine NK-lysin and bovine NK-lysin, 23% to equine NK-lysin, and 46% to zebrafish NK-lysin-like protein. Multiple alignments of Japanese flounder NK-lysin and other known saposin-like proteins revealed that the six cysteine residues important for structural folding are completely conserved. The Japanese flounder NK-lysin gene is approximately 2kb and consists of five exons and four introns. Japanese flounder NK-lysin mRNA constitutive expression was mainly detected in gills, heart, head kidney, intestines, peripheral blood leukocytes (PBLs), spleen and trunk kidney, and was detected at low levels in liver, muscle and ovary. However, expression was not detected in brain, skin and stomach of apparently healthy Japanese flounder. Gene expression of Japanese flounder NK-lysin was not inducible by lipopolysaccharide (LPS) treatment. A synthesized NK-lysin peptide, consisting of 27 amino acid residues, showed antimicrobial activity against Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Photobacterium damselae subsp. piscicida.

Amino Acid Sequence↗

PubMed2006

MR features of physiologic and benign conditions of the ovary.

In reproductive women, various physiologic conditions can cause morphologic changes of the ovary, resembling pathologic conditions. Benign ovarian diseases can also simulate malignancies. Magnetic resonance imaging (MRI) can play an important role in establishing accurate diagnosis. Functional cysts should not be confused with cystic neoplasms. Corpus luteum cysts typically have a thick wall and are occasionally hemorrhagic. Multicystic lesions that may mimic cystic neoplasms include hyperreactio luteinalis, ovarian hyperstimulation syndrome, and polycystic ovary syndrome. Recognition of clinical settings can help establish diagnosis. In endometrial cysts, MRI usually provides specific diagnosis; however, decidual change during pregnancy should not be confused with secondary neoplasm. Peritoneal inclusion cysts can be distinguished from cystic neoplasms by recognition of their characteristic configurations. Ovarian torsion and massive ovarian edema may mimic solid malignant tumors. Recognition of normal follicles and anatomic structures is useful in diagnosing these conditions. In pelvic inflammatory diseases, transfascial spread of the lesion should not be confused with invasive malignant tumors. Radiologic identification of abscess formation can be a diagnostic clue. Many benign tumors, including teratoma, Brenner tumor, and sex-cord stromal tumor, frequently show characteristic MRI features. Knowledge of MRI features of these conditions is essential in establishing accurate diagnosis and determining appropriate treatment.

Diagnosis, Differential↗

PubMed2006

Esophageal cancer: evaluation with triple-phase dynamic CT--initial experience.

PURPOSE: To prospectively assess which phase of a triple-phase dynamic contrast material-enhanced multi-detector row computed tomography (CT) protocol is optimal for visualization of esophageal cancer. MATERIALS AND METHODS: The study was supported by the local ethical committee; all patients gave written informed consent. Thirty-one lesions in 28 consecutive patients (26 men, two women; mean age, 65 years; range, 53-87 years) with histopathologically confirmed esophageal cancer were evaluated with triple-phase dynamic CT performed at 5, 35, and 65 seconds (first arterial, second arterial, and venous phases) after attenuation of 200 HU was obtained at the descending aorta. Qualitative image analysis was performed to assess appearance and conspicuity of the tumor. Appearances of all 31 lesions were classified into three categories-not identifiable, focal enhancement with or without minimal (<1 cm) wall thickening, and focal mass lesion or obvious (>1 cm) wall thickening. Results were compared with surgical or endoscopic ultrasonographic findings. Quantitative assessment included regions-of-interest measurement of the tumor and normal esophageal wall and the difference between those measurements. A paired t test was used to determine which phase showed the highest tumor attenuation and tumor-to-normal esophageal wall attenuation differences. RESULTS: At visual assessment, 30 lesions were identified in the second arterial phase. Of these 30 lesions, eight were focal enhancements; the best conspicuity was during the second arterial phase. Furthermore, seven of these eight lesions were T1 cancers. The remaining 22 lesions were enhanced masses or wall thickening. Twenty-one of these 22 tumors also showed best conspicuity in the second arterial phase. The greatest attenuation of tumors in the second arterial phase was 130.0 HU, and the difference in attenuation between tumor and normal esophageal wall was 50.6 HU in the second arterial phase, which were significantly higher than those in the other two phases (P<.01, each). CONCLUSION: The second arterial phase of dynamic CT is the optimal phase for visualization of esophageal cancer.

Adenocarcinoma↗

PubMed2006

Spectrum of MR features in adenomyosis.

Magnetic resonance (MR) imaging is a highly accurate non-invasive technique for the diagnosis of adenomyosis. Typical MR features include either diffuse or focal thickening of the junctional zone or an ill-defined area of low signal intensity in the myometrium on T2-weighted MR images. Occasionally, the islands of ectopic endometrial tissue can be identified as punctate foci of high signal intensity. Less commonly, adenomyosis can present as a well-circumscribed form known as adenomyoma, adenomyotic cyst characterized by the presence of haemorrhagic cyst, or adenomyomatous polyp protruding into the uterine cavity. The MR appearances of adenomyosis may occasionally fluctuate in response to hormonal stimulation and treatment. MR imaging is helpful not only in monitoring the treatment effect of hormonal therapy, but also in predicting therapeutic effect. In cases of endometrial cancer in the uterus with adenomyosis, evaluation of myometrial invasion may become difficult. Rarely, endometrial cancer may arise directly from adenomyosis resulting from malignant transformation of endometrial glands, creating diagnostic challenges. Differential diagnosis of adenomyosis on MR imaging include physiological myometrial contraction and almost all myometrial lesions, and they should be carefully differentiated from adenomyosis by identifying typical clinical and MR features in these lesions. Precise knowledge of the spectrum of MR features in adenomyosis greatly helps in determining an accurate diagnosis and appropriate management of the patients.

Adenomatous Polyps↗

PubMed2006

Apoptosis induced by chemotherapeutic agents involves c-Jun N-terminal kinase activation in sarcoma cell lines.

Molecular mechanisms underlying chemotherapeutic agent-induced apoptosis in sarcoma cells are not well known. Induction of apoptosis is regulated by several components including mitogen-activated protein kinases (MAPKs) comprising ERK, p38MAPKs, and c-Jun N-terminal kinase (JNK). In the present study, we examined whether activation of JNK is induced by the chemotherapeutic agents cis-diaminedichloroplatinum (cisplatin, CDDP) or doxorubicin (DXR), and whether the ectopic expression of constitutively active (MKK7-JNK1) or dominant-negative form of JNK (dnJNK) influenced apoptosis in response to the CDDP or DXR in sarcoma cell lines MG-63 and SaOS-2. The CDDP or DXR induced JNK activation in the both cell lines, as assessed by Western blotting using phosphospecific antibodies. A transient expression of the activated form of JNK sensitized the MG-63 and SaOS-2 cells to the drug-induced apoptosis, while dnJNK1 reduced the proportion of apoptotic cell death. Apoptosis was determined by flow cytometry using annexin-V Cy5. Collectively, our results indicate that JNK activation is involved in apoptotic cell death in sarcoma cell lines following stimulation with CDDP or DXR.

Antineoplastic Agents↗

PubMed2006

Current status of body MR imaging: fast MR imaging and diffusion-weighted imaging.

The recent technical advances in fast MR imaging have greatly enhanced the clinical value of MR imaging of the body. Advances in T(1)-weighted images have enabled the acquisition of dynamic contrast-enhanced MR imaging, which is currently central to hepatic MR imaging for detection and characterization of liver tumors and is also useful for the evaluation of myometrial invasion in uterine cor-pus cancer. Advances in rapid T(2)-weighted MR imaging with single-shot fast spin-echo images have enabled MR cholangiopancreatography and MR urography. Application of respiratory triggering can also provide T(2)-weighted images of high quality. Cine MR imaging utilizing ultrafast MR sequences enables the assessment of the respiratory motion of the lung for evaluating thoracic wall invasion by tumors. Diffusion-weighted images can provide excellent tissue contrast based on molecular diffusion and have the potential to demonstrate malignant tumors. Quantitative measurement of apparent diffusion coefficient values may also be valuable in distinguishing malignancies from benign lesions.

Diffusion↗

PubMed2006

Primary structure and properties of ribonuclease Bm2 (RNase Bm2) from Bryopsis maxima.

A base non-specific ribonuclease (RNase Bm2) was isolated from a green algae (Ulvophyceae, Bryopsis maxima) as a single band on SDS-PAGE, and its primary structure and enzymatic properties, including base specificity, were investigated. The amino acid sequence of RNase Bm2 was homologous to many RNase T2 family RNases, and their characteristic CAS sequences were also conserved. The molecular mass of RNase Bm2 was 24444 Da, and its optimal pH was 5.5. RNase Bm2 was a poly U preferential RNase, similar to RNase MC1 from bitter gourd. The base specificity of this RNase suggested that the base specificity of the B1- and B2-base binding sites of RNase Bm2 were G > or = U > C >> A and U > G > C >> A, respectively. The estimated active site of RNase Bm2 was very similar to that of RNase MC1 from bitter gourds; however, a tyrosine residue at the B1-base binding site that is conserved for all RNase T2 family RNases was replaced by a tryptophan residue. Here we discuss the effect of this replacement on the base specificity of RNase Bm2 and the phylogenetic relationship of RNase T2 family enzymes.

Amino Acid Sequence↗

PubMed2006

[A case of advanced rectal carcinoma with multiple lung metastases responding to irinotecan combined with 5-fluorouracil and l-leucovorin (IFL) as neoadjuvant chemotherapy (NAC)].

A 53-year-old man, admitted for inguinal hernia, complained of body weight loss in a preoperative condition check. We examined the digestive tract and diagnosed stage IV advanced rectal carcinoma with multiple lung metastases. It caused ileus, so emergency colostomy was performed. After that his general condition recovered, and two cycles of neoadjuvant chemotherapy (NAC) by irinotecan combined with 5-fluorouracil and l-leucovorin (IFL) therapy were performed on an outpatient basis. Lung metastatic nodules disappeared. We established a diagnosis of down staging for stage IIIa, and performed a lower anterior resection with D 2 lymph node dissection to allow a curability-A resection. The pathological effect of NAC was Grade 2. Post-operatively, two cycles of IFL therapy were then performed. There has been no sign of recurrence, and no adverse effects by chemotherapy have been seen during this treatment. Thus, NAC by IFL therapy can be one of the useful treatment approaches for patients with advanced rectal cancer.

Adenocarcinoma↗

PubMed2005

Development of gene transfer technology for black tiger shrimp, Penaeus monodon.

An effective foreign gene transfer method for shrimp would have several potential uses in the shrimp culture industry, such as in preventing infectious diseases. We evaluated two gene transfer methods and used black tiger shrimp, Penaeus monodon, as a model target species. For a promoter, we used the 1,592-bp promoter region of the EF-1alpha gene, a house-keeping gene, of kuruma shrimp Marsupenaeus japonicus. The promoter region was linked to either the gene for green fluorescence protein (GFP) or the gene for chloramphenicol acetyl transferase (CAT). The fusion genes were designated pJEF-GFP and pJEF-CAT, respectively. The pJEF-GFP gene was introduced into fertilized eggs of black tiger shrimp by microinjection and particle gun bombardment. The survival rate of the microinjected eggs was 17.6%, and 1.0% of the treated embryos were found to be GFP-positive. However, the GFP-positive embryos were damaged and embryogenesis did not progress. The survival rate of the particle-bombarded eggs was 60.6%, and 0.42% of the treated embryos were found to be GFP-positive. Ubiquitous GFP expression was observed from 8 hr post-fertilization and these embryos developed and hatched normally. The pJEF-CAT gene was introduced into fertilized eggs of black tiger shrimp using the optimized conditions of the particle gun bombardment. CAT activity was observed from 1 to 7 days post-fertilization, with the highest activities being observed at 5 and 7 days post-hatching.

Animals↗

PubMed2005

Dysmenorrhea: evaluation with cine-mode-display MR imaging--initial experience.

PURPOSE: To prospectively evaluate uterine contractility during menstruation and its relation to primary dysmenorrhea by using magnetic resonance (MR) imaging with cine mode display. MATERIALS AND METHODS: The university ethics committee approved the study protocol, and all subjects gave written informed consent. Nineteen healthy women were examined during menstrual cycle days 1-3 by using a 1.5-T-magnet unit. Sixty serial half-Fourier rapid acquisition with relaxation enhancement MR images of the uterus were obtained every 3 seconds for 3 minutes and displayed in cine mode. MR images were analyzed in terms of thickness of the inner low-signal-intensity myometrial layer, presence of endometrial distortion, and uterine peristalsis detectability. Pain was assessed by using a four-point scale. For 56 MR imaging cases, the association between MR imaging findings and pain degree was examined with Spearman correlation and Mann-Whitney tests. MR imaging findings in the dysmenorrheic and eumenorrheic subject groups were compared by using Mann-Whitney and chi(2) tests. The area of the uterine myometrium in both groups was calculated for quantitative assessment of uterine contraction and was compared between the groups by using the Student t test. RESULTS: MR imaging findings revealed marked changes during cycle days 1-3. Thickness of the inner low-signal-intensity myometrial layer and endometrial distortion were significantly associated with pain degree (P < .001), while uterine peristalsis was undetectable when pain was severe or moderate. The area of the uterine myometrium significantly decreased during cycle days 1-3 in the dysmenorrheic group, as compared with that in the eumenorrheic group (P = .010). CONCLUSION: MR imaging features of the uterus on cycle days 1-3 correlated with pain degree. Cine-mode-display MR imaging is a potential tool for evaluating dysmenorrhea.

Adult↗

PubMed2005

High 18F-fluorodeoxyglocose uptake in adrenal histoplasmosis; a case report.

Adrenal histoplasmosis is one of the most common adrenal granulomatous infections in endemic areas. Although CT or MRI findings of adrenal histoplasmosis have been documented, there are no reports regarding 18F-fluorodeoxyglocose (FDG) positron emission tomography (PET) findings. We report a case of bilateral adrenal histoplasmosis showing a significantly high uptake of 18F-fluorodeoxyglocose on PET study. Adrenal histoplasmosis should be considered as one of the differential diagnoses in cases of adrenal tumors with intense FDG uptake, even in non-endemic areas.

Adrenal Gland Diseases↗

PubMed2005

Posterior cul-de-sac obliteration associated with endometriosis: MR imaging evaluation.

PURPOSE: To retrospectively evaluate the accuracy of magnetic resonance (MR) imaging in depicting posterior cul-de-sac obliteration in patients with endometriosis. MATERIALS AND METHODS: Institutional review board approval was not required for this retrospective study, but informed consent was obtained from all patients. MR images obtained between January 1989 and December 2000 in 57 women (mean age, 39 years; age range, 26-52 years) with histologically confirmed endometriosis were retrospectively evaluated by four radiologists independently. All patients underwent laparotomy or laparoscopy less than 1 month after MR imaging. MR images were evaluated for the presence and location of endometrial implants and adhesions. MR images were also scored for the presence of five findings: retroflexed uterus, elevated posterior vaginal fornix, intestinal tethering or tethered appearance of rectum in direction of uterus, faint strands between uterus and intestine, and fibrotic plaque or nodule covering serosal surface of the uterus. Interobserver agreement for each of the five findings and for the overall diagnosis of cul-de-sac obliteration was calculated. Sensitivity, specificity, accuracy, positive and negative predictive values, and kappa statistics were determined. RESULTS: Laparotomy or laparoscopy revealed posterior cul-de-sac obliteration in 30 patients. Overall, the four radiologists had mean accuracies of 89.0% and 76.3% for diagnosing endometrial implants and adhesions, respectively, at MR imaging. Overall, the radiologists achieved mean sensitivity, specificity, accuracy, and positive and negative predictive values of 68.4%, 76.0%, 71.9%, 76.6%, and 68.5%, respectively, in diagnosing posterior cul-de-sac obliteration. The best accuracy (mean value, 64.5%) was obtained with the finding of fibrotic plaque in the uterine serosal surface. Readers agreed on the observations 63.2%-91.2% of the time. For the impression of the presence or absence of posterior cul-de-sac obliteration, interobserver agreement varied between substantial and moderate: Mean interobserver agreement was 78.4% (range, 70.2%-84.2%), and mean kappa was 0.57 (range, 0.40-0.67). Mean accuracy of MR imaging for diagnosing posterior cul-de-sac obliteration was 71.9%. CONCLUSION: These results suggest that use of the described MR imaging findings may enable diagnosis of posterior cul-de-sac obliteration.

Adult↗

PubMed2005

A semiautomated technique for evaluation of uterine peristalsis.

PURPOSE: To evaluate the capability of a newly developed semiautomatic analysis technique for evaluation of uterine peristalsis in comparison with visual assessment. MATERIALS AND METHODS: Cine magnetic resonance (MR) images were obtained from 16 normal volunteers in periovulatory phase. Sixty-eight studies were evaluated by both visual evaluation and by a semiautomated computer assisted software. The software was developed by applying an automated contour tracking method and enables objective analysis of frequency, amplitude, velocity, and direction. Assessments were based on: 1) the recognition of peristalsis, 2) peristaltic direction and frequency, and 3) the way of recognizing peristaltic direction. The data obtained by both modalities were compared with those of previously reported ultrasound (US) findings. RESULTS: Uterine peristalsis was identified in all studies by both objective and visual analyses. There was no significant difference in the identification of peristalsis, recognition of peristaltic directions, or peristaltic frequency (P > 0.05). Data were well in accordance with those in US literature. Peristaltic direction was recognized either by configuration change in the endometrium or by conduction of low signal intensity in the subendometrial myometrium and there was statistically no difference. CONCLUSION: Evaluation of uterine peristalsis by the semiautomatic analysis accorded well with the results obtained visual assessments and previous US findings.

Adult↗