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Biomedical subjects

K Okamoto

Publications and source records attributed to K Okamoto.

At least 19 recordsLinked to original sources
PubMed2007

Effects of epidural anaesthesia on surgical stress-induced immunosuppression during upper abdominal surgery.

BACKGROUND: Previously, we have demonstrated that surgical stress rapidly induced transient hyporesponsiveness of blood cells to endotoxin and that monocyte mCD14 and HLA-DR expression decreased soon after the start of surgery under general anaesthesia. This study was designed to investigate the effects of epidural anaesthesia on surgical stress-induced immunosuppression in patients undergoing upper abdominal surgery. METHODS: After having obtained informed consent, patients were randomly allocated to receive general anaesthesia (Group G) or general anaesthesia with epidural anaesthesia (Group E). Perioperative changes in neutrophil phagocytic activity, neutrophil respiratory burst activity, monocyte mCD14 and HLA-DR expression, plasma IL-10 concentration, and the LPS-induced TNF-alpha production in whole blood were measured. RESULTS: Surgical stress rapidly depressed neutrophil phagocytic activity, monocyte mCD14 and HLA-DR expression, and LPS-induced TNF-alpha production ex vivo (P < 0.05 vs preoperation) in both Group G and Group E. In contrast, the plasma IL-10 concentration increased significantly 2 h after the start of surgery (P < 0.05) in both groups. There were no significant differences between the two groups. The neutrophil respiratory burst activity did not change during the operation in either group. CONCLUSION: This study showed that the innate immune system is suppressed from the early period of upper abdominal surgery. Subgroup analysis suggested that epidural anaesthesia to T4 dermatome as well as general anaesthesia may not protect patients from this immunosuppression. These results in part explain the impairment of host-defense mechanisms seen in the perioperative period.

Anesthesia, Epidural↗
PubMed2006

Fluctuating serotonergic function in premenstrual dysphoric disorder and premenstrual syndrome: findings from neuroendocrine challenge tests.

RATIONALE: Premenstrual dysphoric disorder (PMDD) has been assumed to be a subtype of premenstrual syndrome (PMS) with depressive symptoms, such as depressive mood, tension, anxiety, and mood liability during luteal phase. At present, no conclusion has been established about serotonergic function in PMDD. OBJECTIVE: The purpose of this study was to investigate the serotonergic function of PMDD subjects in comparison to PMS without PMDD subjects and normal controls via neuroendocrine challenge tests. SUBJECTS AND METHODS: Twenty-four women (seven with PMDD, eight with PMS without PMDD, and nine normal controls) were tested on three occasions (follicular phase, early luteal phase, and late luteal phase) receiving paroxetine 20 mg orally as a serotonergic probe at 8:00 A: .M: . Plasma ACTH and cortisol were measured prior to the administration and every hour for 6 h thereafter. RESULTS: As a whole, there were significant differences in serotonergic function measured by ACTH and cortisol responses to paroxetine challenge across these three groups. PMDD subjects showed higher serotonergic function in follicular phase but lower serotonergic function in luteal phase, compared with women with PMS without PMDD and normal controls. CONCLUSION: The present findings suggest that PMDD women have fluctuating serotonergic function across their menstrual cycles and that the pattern may be different from PMS without PMDD.

Administration, Oral↗
PubMed2006

K-ras mutations and cell kinetics in Helicobacter pylori associated gastric intestinal metaplasia: a comparison before and after eradication in patients with chronic gastritis and gastric cancer.

BACKGROUND: Helicobacter pylori related gastric intestinal metaplasia (IM) is considered to be a precancerous lesion. AIMS: To identify the effects of H pylori eradication on K-ras mutations, cell kinetics in IM and histological changes in patients with and without gastric cancers in a one-year prospective study. METHODS: Patients included group A (n = 39), chronic gastritis, and group B (n = 53), intestinal-type early gastric cancer patients who had all undergone endoscopic mucosal resection (n = 25) or surgical resection (n = 28). K-ras codon 12 mutations in IM were examined, followed by DNA sequencing analysis. Proliferating and apoptotic cells were detected with anti-Ki-67 antibody and using the TUNEL method, respectively. RESULTS: The incidence of K-ras mutations in the cancer was only 3.8%. The mutant K-ras in IM was observed more frequently in group A (46.2%) than in group B patients (1.9%) (p<0.005). After eradication, the K-ras mutations significantly declined to 12.8% in group A (p<0.005). The mutation pattern of K-ras codon 12 before eradication was that GGT was mainly changed to AGT (50%) in group A. AGT transformation was not affected by treatment. Apoptosis in IM showed an increase after H pylori eradication in both groups (p<0.05 in group A) although no histological improvement in IM was observed. The monocyte score was significantly higher in group A than in group B (p<0.05); the score improved significantly after eradication. CONCLUSIONS: K-ras mutations in IM do not always play a role in gastric carcinogenesis but cell kinetics, especially apoptosis, in IM may contribute to it. There are early events in K-ras mutations which are influenced by H pylori infection; some mutations may also be selected by eradication. These unstable K-ras mutations in IM may be related to lymphocyte infiltration caused by H pylori infection.

Apoptosis↗
PubMed2006

Contribution of peripheral 5-HT2A or 5-HT3 receptors to Fos expression in the trigeminal spinal nucleus produced by acute injury to the masseter muscle during persistent temporomandibular joint inflammation in rats.

We investigated the contribution of peripheral 5-HT2A or 5-HT3 receptors to Fos expression in the trigeminal spinal nucleus (VSP) following acute masseter muscle injury in male rats with or without temporomandibular joint (TMJ) inflammation persisting for 7 days. TMJ inflammation was evoked by an injection of complete Freund's adjuvant (CFA). Two hours after formalin injection into the masseter muscle produced Fos-like immunoreactivity (Fos-LI) in several regions of the VSP and upper cervical spinal cord (C2), such as ventrolateral (vl) area of the trigeminal subnucleus caudalis (Vc)/subnucleus interpolaris (Vi) transition (vl-Vi/Vc), paratrigeminal nucleus (dPa5), middle portion of the Vc (mid-Vc) and Vc/C2 transition (Vc/C2) regions in both groups. Significant increases in the number of Fos-LI were observed in these areas in CFA group compared with non-CFA group. TMJ inflammation alone did not induce a significant level of Fos-LI in the VSP. In order to assess the effect of antagonizing 5-HT2A or 5-HT3 receptors on formalin-induced Fos-LI, rats were pre-treated with local (masseter muscle) administration of ketanserin or tropisetron (0.01, 0.1 mg/rat) 20 min prior to formalin injection. In CFA group, these antagonists given locally reduced the Fos-LI response in the laminae I-II at the mid-Vc and Vc/C2 regions. These antagonists reduced the Fos-LI response in the dPa5, but not in the vl-Vi/Vc region. The Fos-LI response was not affected by i.v. administration of ketanserin (0.01, 0.1 mg/rat) or tropisetron (0.01 mg/rat). In non-CFA group, these antagonists given locally did not reduce the Fos-LI response. These results suggest that peripheral 5-HT2A and 5-HT3 receptors contribute to nociceptive processing in the masseter muscle in TMJ inflammatory conditions.

Animals↗
PubMed2006

Laparoscopic incisional hernia repair. A new mesh fixation method without stapling.

BACKGROUND: Recent advances in laparoscopic surgery have made various abdominal surgeries possible. To avoid wound infection, mesh repair of abdominal incisional hernias is performed laparoscopically. Here we present a new procedure to fix mesh to the abdominal wall. SURGICAL TECHNIQUE: Four anchoring sutures are made using a suture-grasping device; the additional transabdominal sutures are then made with a modified double-needle device. Additional circumferential fixation with tacks is not necessary. CONCLUSIONS: This new mesh fixation method involves simple suturing techniques and is less time consuming than the conventional procedure.

Abdominal Wall↗
PubMed2006

"Ventral" area in the rat auditory cortex: a major auditory field connected with the dorsal division of the medial geniculate body.

The rat auditory cortex is made up of multiple auditory fields. A precise correlation between anatomical and physiological areal extents of auditory fields, however, is not yet fully established, mainly because non-primary auditory fields remain undetermined. In the present study, based on thalamocortical connection, electrical stimulation and auditory response, we delineated a non-primary auditory field in the cortical region ventral to the primary auditory area and anterior auditory field. We designated it as "ventral" area after its relative location. At first, based on anterograde labeling of thalamocortical projection with biocytin, ventral auditory area was delineated as a main cortical terminal field of thalamic afferents that arise from the dorsal division of the medial geniculate body. Cortical terminal field (ventral auditory area) extended into the ventral margin of temporal cortex area 1 (Te1) and the dorsal part of temporal cortex area 3, ventral (Te3V), from 3.2-4.6 mm posterior to bregma. Electrical stimulation of the dorsal division of the medial geniculate body; evoked epicortical field potentials confined to the comparable cortical region. On the basis of epicortical field potentials evoked by pure tones, best frequencies were further estimated at and around the cortical region where electrical stimulation of the dorsal division of the medial geniculate body evoked field potentials. Ventral auditory area was found to represent frequencies primarily below 15 kHz, which contrasts with our previous finding that the posterodorsal area, the other major recipient of the dorsal division of the medial geniculate body; projection, represents primarily high frequencies (>15 kHz). The posterodorsal area is thought to play a pivotal role in auditory spatial processing [Kimura A, Donishi T, Okamoto K, Tamai Y (2004) Efferent connections of "posterodorsal" auditory area in the rat cortex: implications for auditory spatial processing. Neuroscience 128:399-419]. The ventral auditory area, as the other main cortical region that would relay auditory input from the dorsal division of the medial geniculate body to higher cortical information processing, could serve an important extralemniscal function in tandem with the posterodorsal area. The results provide insight into structural and functional organization of the rat auditory cortex.

Acoustic Stimulation↗
PubMed2006

A Novel real-time dosimetry technique based on radiation-induced surface activation.

A novel real-time dosimetry technique based on radiation-induced surface activation (RISA) phenomenon has been proposed that is similar to ultraviolet surface activation known typically in anatase-type titanium dioxide. It has been found that the RISA phenomenon occurs on the surface of an oxidised semiconductor or oxidised metal film by radiation incidence. The RISA dosemeter has the following advantageous characteristics: (1) output of the RISA dosemeter is proportional to the dose equivalent rate in harsh environments, (2) fluctuation of output of the RISA dosemeter irradiated by (60)Co gamma-rays is <2.5% beyond the total dose equivalent of 1.8 MSv, (3) the transient current observed in simple insulators for a few seconds or more after onset of irradiation was not detected in the RISA dosemeter and (4) this dosemeter worked well even at high temperatures.

Computer Systems↗
PubMed2006

Arrayed-waveguide grating with uniform loss properties over the entire range of wavelength channels.

We propose an arrayed-waveguide grating that shows uniform loss properties over the entire range of wavelength channels by combining two light waves with adjacent diffraction orders at its output. We applied this configuration to an arrayed-waveguide grating with 32 channels and a 50 GHz spacing and were able to reduce the deviations in loss to less than 1.0 and 1.8 dB over one and three free spectral ranges, respectively.

Journal Article↗
PubMed2006

Erasure of methylation imprint at the promoter and CTCF-binding site upstream of H19 in human testicular germ cell tumors of adolescents indicate their fetal germ cell origin.

Genome-wide epigenetic modification plays a crucial role in regulating genome functions at critical stages of development. In particular, DNA methylation is known to be reprogrammed on a genome-wide level in germ cells and in preimplantation embryos, although it is relatively stable in somatic cells. In this reprogramming process, the genome becomes demethylated, and methylated de novo during later stages of development. Reprogramming of DNA methylation in male germ cells has not been fully investigated. Testicular germ cell tumors (TGCTs) possess a pluripotential nature and display protean histology from germ cells to embryonal and somatic cell differentiation. These properties make TGCT a unique model for studying germ cell development and gametogenesis in respect of DNA reprogramming. In order to obtain an insight into the epigenetic dynamics of TGCTs, we conducted a comprehensive analysis of differential methylated regions (DMRs) on H19 and IGF2 in TGCTs compared with testicular malignant lymphomas. In the present study, we show that methylation imprint at the promoter and CTCF-binding site upstream of H19 was completely erased in both seiminomatous and non-seminomatous TGCTs, whereas differential methylation was observed in testicular lymphomas. The erasure of methylation imprint was also observed in TGCTs with malignant transformation. We found biallelic unmethylation at the promoter and the CTCF-binding site upstream of H19 is required, but not sufficient for the biallelic expression of H19 in TGCTs. These data suggest that factors other than methylation contribute to transcriptional regulation of imprinted genes in TGCTs. The present data have shown that TGCTs carry distinctive epigenetic profiles at the core-imprinting domain of H19/IGF2 from other neoplasms of somatic cell origin. The data also suggest that both seminomatous and non-seminomatous TGCTs carry methylation profiles similar to fetal germ cells, but not adult germ cells, indicating the origin of TGCTs as fetal germ cells.

Adolescent↗
PubMed2006

Spindle cell metaplasia arising in thyroid adenoma: characterization of its pathology and differential diagnosis.

Spindle cell metaplasia in thyroid adenoma or carcinoma is rare and its pathological features are not well characterized. Distinction of this entity from medullary or anaplastic carcinoma has an important clinical implication. We encountered a case of thyroid follicular adenoma associated with spindle cell metaplasia. It showed "tumor in tumor appearance" and neoplastic spindle cells were positive for thyroglobulin, thyroid transcription factor-1, vimentin and focally chromogranin A and somatostatin (SS). MIB-1 index was <1%. Ultrastructure of the spindle cells was reminiscent of follicular cell origin. From the findings from our case, spindle cell metaplasia appears to be a benign clinical entity, suggestive of multidirectional differentiation of follicular cells.

Adenoma↗
PubMed2006

Bronchogenic glomangiomyoma with local intravenous infiltration.

Most glomus tumours occur in the dermis and subcutaneous tissues. Lung glomus tumours are quite rare. The current authors present the first reported case of a lung-derived glomangiomyoma, the rarest variant of glomus tumour. A 56-yr-old female was admitted with haemoptysis. Chest computed tomography showed an approximately 5-cm-diameter mass in the right lower lobe with mucoid impaction. After a right lower lobectomy, a diagnosis of glomangiomyoma was made. The tumour had grown endobronchially and its maximal diameter was 5.5 cm. Although cytologically benign, glomus tumour cells had visibly infiltrated neighbouring vessels. These results suggest that a bronchogenic glomangiomyoma has a low-grade malignancy potential and warrants close follow-up.

Carcinoma, Bronchogenic↗
PubMed2006

Dietary fat and meat intake and idiopathic pulmonary fibrosis: a case-control study in Japan.

SETTING: There is sparse epidemiologic information regarding the role of dietary factors in the development of idiopathic pulmonary fibrosis (IPF). OBJECTIVE: To examine the relationship between specific types of fatty acids and selected foods high in fat and IPF in Japan. DESIGN: Included were 104 cases aged > or = 40 years who had been diagnosed in the last 2 years in accordance with the most recent criteria. Controls aged > or = 40 years consisted of 56 hospitalised patients diagnosed as having acute bacterial pneumonia and four out-patients with common cold. RESULTS: Intake of saturated fatty acids, mono-unsaturated fatty acids, n-6 polyunsaturated fatty acids and meat was independently associated with an increased risk of IPF. Specifically, the multivariate OR for comparison of the highest with the lowest quartile of intake of saturated fatty acids was 6.26 (95%CI 1.79-24.96, P for trend = 0.01) and for meat it was 7.19 (95%CI 2.15-27.07, P for trend = 0.02). Intake of cholesterol, n-3 polyunsaturated fatty acids, fish, eggs and dairy products was not related to the risk. CONCLUSION: These findings suggest that consumption of saturated fatty acids and meat may increase the risk of IPF.

Adult↗
PubMed2005

Laparoscopic lymph node dissection around the inferior mesenteric artery for cancer in the lower sigmoid colon and rectum: is D3 lymph node dissection with preservation of the left colic artery feasible?

BACKGROUND: When we perform laparoscopic lymph node dissection around the inferior mesenteric artery (IMA), we preserve the left colic artery (LCA) to maintain the blood supply to the proximal sigmoid colon. In this study, we present our laparoscopic D2 and D3 lymph node (LN) dissection technique and evaluate its applicability and safety. METHODS: We performed LN dissection on 23 rectal and lower sigmoid colon cancer cases from April 2002 to December 2004. For D3 LN dissection, the incision to the mesosigmoid extends to just before the root of the IMA, which is exposed with an ultrasonic cutting and coagulating surgical device to avoid bleeding. Then, the arterial wall is exposed with a dissecting electrocautery spatula down to the LCA, at least 2 cm of which is exposed. Adipose tissue surrounding the IMA and inferior mesenteric vein is dissected. For D2 LN dissection, we partially expose the IMA to confirm the location of the LCA. RESULTS: The mean times taken for D2 and D3 LN dissections were 36.2 and 68.2 min, respectively. Both procedures took longer in male patients. There was a trend for the procedure overall to take less time in female patients. However, D2 dissection took significantly longer in male than female patients (p < 0.05). In women, D3 dissection took significantly longer than D2 (p < 0.05), but this trend was not seen in men. Increased experience among surgeons with this procedure was associated with significantly faster LN dissections in men (p < 0.05), but not in women (p = 0.493). Pearson product moment analysis identified a relationship between body mass index (BMI) and the time taken for D2 LN dissection (r = 0.765), but not D3 LN dissection (r = 0.158). There was no treatment-related morbidity with this technique. CONCLUSIONS: This method was safe and feasible for all patients in this series, but takes longer to perform in male patients.

Aged↗
PubMed2005

Topography of projections from the primary and non-primary auditory cortical areas to the medial geniculate body and thalamic reticular nucleus in the rat.

The functional significance of parallel and redundant information processing by multiple cortical auditory fields remains elusive. A possible function is that they may exert distinct corticofugal modulations on thalamic information processing through their parallel connections with the medial geniculate body and thalamic reticular nucleus. To reveal the anatomical framework for this function, we examined corticothalamic projections of tonotopically comparable subfields in the primary and non-primary areas in the rat auditory cortex. Biocytin was injected in and around cortical area Te1 after determining best frequency at the injection site on the basis of epicortical field potentials evoked by pure tones. The rostral part of area Te1 (primary auditory area) and area temporal cortex, area 2, dorsal (Te2D) (posterodorsal auditory area) dorsal to the caudal end of area Te1, which both exhibited high best frequencies, projected to the ventral zone of the ventral division of the medial geniculate body. The caudal end of area Te1 (auditory area) and the rostroventral part of area Te1 (a part of anterior auditory field), which both exhibited low best frequencies, projected to the dorsal zone of the ventral division of the medial geniculate body. In contrast to the similar topography in the projections to the ventral division of the medial geniculate body, collateral projections to the thalamic reticular nucleus terminated in the opposite dorsal and ventral zones of the lateral and middle tiers of the nucleus in each pair of the tonotopically comparable cortical subfields. In addition, the projections of the non-primary cortical subfields further arborized in the medial tier of the thalamic reticular nucleus. The results suggest that tonotopically comparable primary and non-primary subfields in the auditory cortex provide corticofugal excitatory effects to the same part of the ventral division of the medial geniculate body. On the other hand, corticofugal inhibition via the thalamic reticular nucleus may operate in different parts of the ventral division of the medial geniculate body or different thalamic nuclei. The primary and non-primary cortical auditory areas are presumed to subserve distinct gating functions for auditory attention.

Acoustic Stimulation↗
PubMed2005

Monoclonal antibody A7-superparamagnetic iron oxide as contrast agent of MR imaging of rectal carcinoma.

Superparamagnetic iron oxide (SPIO)-based colloid has been used clinically as a tissue-specific magnetic resonance contrast agent. We coupled monoclonal antibody A7 (Mab A7), which reacts specifically with human colorectal carcinoma, to Ferumoxides (SPIO) and examined the accumulation of this conjugate in xenografted tumours in nude mice. We examined in vitro immunoreactivity of Mab A7 coupled to Ferumoxides and its in vivo distribution in nude mice with human colorectal carcinoma. Magnetic resonance imaging of tumour-bearing nude mice was performed 72 h after injection of A7-Ferumoxides. A7-Ferumoxides retained binding activities that were nearly identical to intact Mab A7. More of the radiolabelled A7-Ferumoxides accumulated in the tumour than normal mouse IgG-Ferumoxides from 12 h onwards after injection (P<0.05). Both A7-Ferumoxides and normal mouse IgG-Ferumoxides disappeared from blood linearly over time. The accumulation levels in normal tissue decreased linearly over time but were lower than levels in tumours from 6 h. In magnetic resonance T2-weighted imaging of the tumour-bearing nude mice, signal intensity was reduced at the margin of the tumour by injection of A7-Ferumoxides. Mab A7 coupled to Ferumoxides is potentially suitable as a magnetic resonance contrast agent for detecting local recurrence of rectal carcinoma.

Animals↗
PubMed2005

Experimental observation of the 1/3 magnetization plateau in the diamond-chain compound Cu3(CO3)2(OH)2.

The magnetic susceptibility, high field magnetization, and specific heat measurements of Cu3(CO3)2(OH)2, which is a model substance for the frustrating diamond spin chain model, have been performed using single crystals. Two broad peaks are observed at around 20 and 5 K in both magnetic susceptibility and specific heat results. The magnetization curve has a clear plateau at one third of the saturation magnetization. The experimental results are examined in terms of theoretical expectations based on exact diagonalization and density matrix renormalization group methods. An origin of magnetic anisotropy is also discussed.

Journal Article↗
PubMed2005

Differential modulation of TMJ neurons in superficial laminae of trigeminal subnucleus caudalis/upper cervical cord junction region of male and cycling female rats by morphine.

Sex differences in the cellular responses to morphine were examined in an animal model of temporomandibular joint (TMJ) pain. TMJ-responsive neurons were recorded in the superficial laminae at the trigeminal subnucleus caudalis/upper cervical cord (Vc/C(2)) junction region, the initial site of synaptic integration for TMJ afferents, in male and cycling female rats under barbiturate anesthesia. Unit activity was evoked by local injection of bradykinin into the TMJ capsule at 30 min intervals and the effects of morphine sulfate (0.03-3 mg/kg, i.v.) were assessed by a cumulative dose regimen. Morphine caused a dose-related inhibition of bradykinin-evoked unit activity in males and diestrous females in a naloxone-reversible manner, while evoked unit activity in proestrous females was not reduced. The apparent sex hormone-related aspect of morphine analgesia was selective for evoked unit activity, since the spontaneous activity of TMJ units was reduced similarly in all groups, while the convergent cutaneous receptive field area of TMJ units did not change in any group. These results were consistent with the hypothesis that sex hormone status interacts with pain control systems to modify neural activity at the level of the Vc/C(2) junction region relevant for TMD pain.

Action Potentials↗