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Biomedical subjects

M Tamura

Publications and source records attributed to M Tamura.

At least 37 records · Page 2Linked to original sources
PubMed2004

[Radiology of radiosurgery].

Proper understanding of the fundamentals of radiosurgery and the main principles of radiobiology is a key point for the development and adaptation of therapeutic strategies and for the definition of indications. The prediction of local effects of radiosurgery requires taking into account both the target Volume and the marginal dose (energy,...) and not only the marginal dose which alone is poorly predictive of the outcome. Other additional factors such as topography, age, previous irradiations,... are likely to influence this risk relationship. The comparison of different dose regimens leads to proposing theoretical models for calculating radiobiological equivalences: the Biological Equivalent Dose (BED) Using these models one can think in terms of the practical consequences of dose fractionation. This allows, depending on the medical context, identifying the potential advantages of the radiosurgery or of a fractionated regimen. For small mid-sized vestibular schwannomas this approach indicates a clear advantage for a single-dose regimen. Retrospectively it has been possible to identify the dose-Volume relationship to the risk of neuropathy for facial motor function, facial sensitivity, and hearing.

Dose Fractionation, Radiation↗
PubMed2004

[Changing radiological results, pitfalls and criteria of failure].

RATIONALE: To evaluate the morphological changes occurring during the Years following radiosurgery in order to better define the cure-failure parameters. MATERIAL AND METHODS: Between July 1992 and January 2002 the otoneurosurgical group of the Timone Hospital in Marseille have operated 1000 vestibular schwannomas. The MR imaging performed before (at diagnosis) during and after radiosurgery (6 months, 1 year, 2 years, 3 years, 5 years, 7 years and 10 years) was carefully studied. Systematically six lenghts measurements were obtained for each lesion. RESULTS: Preoperatively 129 patients were had progressive tumors. At time of radiosurgery, median tumor Volume was 732mm3 (mean: 1346, range: 20-14405). According to the Koos topographical classification, lesions were stage I in 80 patients, stage II in 538 patients, stage III in 322 patients and stage IV in 56 patients. A clear loss of the central enhancement was visible on the postoperative MR control at 6 months and/or 1 Year in 45.5% of patients. In 64% of these patients, this loss of the central contrast enhancement have disappeared. A significant increase of the tumor size was recorded in 15% of the patients. The median increase was 62% (mean: 78%, range: 30-350%). Progression led to salvage surgery (either resection or radiosurgery), in only 3% of the patients. CONCLUSION: The specificity of the morphological changes after radiosurgery, when ignored, can lead to misinterpretation and eventually to inappropriate decisions, dangerous for the patient. The analysis of our results had led us to consider continuous progression after 3 Years as mandatory to retain the diagnosis of failure.

Diffusion Magnetic Resonance Imaging↗
PubMed2004

Injury of the lacrimal component of the nervus intermedius function after radiosurgery versus microsurgery.

RATIONALE: Due to the synergetic role of the facial nerve and the nervus intermedius in the mechanical protection of the eye, vestibular schwannomas (VS) and/or their treatment are dangerous for the visual function. Our goal was to evaluate and compare the impact of the tumor itself, and the microsurgery (MS) or radiosurgery (RS). MATERIAL AND METHOD: A functional questionnaire evaluating among other items the patient's complaints related to the eye was addressed to a series of 100 patients, 3 years after GKS of a previously unresected unilateral VS. Answers were compared with those of a group of 100 patients operated microsurgically. A Shirmer test was additionally performed before radiosurgery, and more than 2 years after radiosurgery in 46 patients. RESULTS: The risk of dry eye and burning eye was much higher in patients operated by MS compared to patients operated by GKS due to the high incidence of facial palsy in the former (57/99) and the its absence in the later (0/80). In the population operated microsurgically, the presence of a permanent facial palsy (57 patients among 99 responding to the questionnaire) was, of course, associated with a high rate of complaints about burning eye (n=18) and crying eye (n=23). Among patients from the two arms with no facial palsy, a dry eye was reported by 8/64 after GKS and 7/42 after MS (NS) and a burning eye by 9/64 after GKS and 9/42 after MS (NS). Thus patients with no clinical signs of impairement of the VII motor nerve accounted for 14% of the cases signs indicating injury of the intermedius nerve with the same probability whatever the kind of surgery. When no permanent facial palsy was observed a crocodile tear syndrome was more frequently observed after MS (4/42 versus 1/64, p=0.07). This suggests an early lesion of the VII motor and intermedius, and a subsequent abnormal regrowth. The only patient reporting a crocodile tear syndrome after GKS turned out to have presented transiently a discret deficit of orbicular muscle signaling transient partial facial nerve injury. In absence of facial palsy, a "crying eye" was reported more frequently after MS (16/42 versus 9/64, p=0.01), leading us to suspect frequent infraclinical VII nerve injury in patients with no obvious facial palsy operated by MS. Patients tested with Shirmer test, before and more than 2 Years after, were improved in 28.3%, stable in 56.5%, and worse in 15.2%. CONCLUSIONS: This study is the first demonstrating that radiosurgery can induce nervus intermedius injury in a small percentage of cases (14%). These patients had been treated 11 years ago with what we can consider as "archeoGKS technology" compared to today's refinements. The impact of modern GKS on the nervus intermedius is currently under evaluation in our group. However, symptoms related to the eye either due to the injury of the nervus intermedius or of the VII motor or both are much more frequent after MS than after RS.

Adolescent↗
PubMed2004

[Preserving hearing function after Gamma Knife radiosurgery for unilateral vestibular schwannoma].

OBJECTIVE: The majority of the patients still lose hearing function in spite of the technical advances in microsurgery. We wanted to evaluate preservation of hearing function potential after Gamma Knife Surgery. MATERIAL AND METHOD: In Marseille, we performed 1000 Gamma-Knife procedures for vestibular schwannomas between July 1992 and January 2002. This population included 175 patients undergoing first intention surgery for a unilateral schwannoma with functional preoperative hearing (Gardner and Robertson 1 or 2) who were studied with a follow-up longer than 3 Years. Univariate and multivariate analysis was performed. RESULTS: Numerous parameters significantly influenced the probability of functional hearing preservation at 3 years. The overall rate of preservation was 60%. The main parameters of predictability were limited hearing loss (Gardner and Robertson stage 1 versus 2) before radiosurgery, presence of tinnitus as the initial symptom, young age and the small tumor size. Preservation of functional hearing at 3 years was 77.8% when the patient was initially in stage I, 80% when the patient's first symptom was tinnitus, and 95% when the patient had both. In these patients, the probability of functional preservation at 5 years was 84%. CONCLUSION: We report a large population of patients treated by radiosurgery with initial functional hearing. These results demonstrate that a large percentage of selected patients can preserve functional hearing after Gamma Knife Surgery, their chances of functional preservation being greater than after microsurgery or simple surveillance.

Adolescent↗
PubMed2004

[Gamma Knife surgery for VII nerve schwannomas].

RATIONALE: Radical resection of VII nerve schwannomas classically implies a high risk of severe facial palsy. Due to the rarity of facial palsy after Gamma Knife surgery (GKS) of vestibular schwannomas the evaluation of GKS in this specific difficult group of patient appears rational. We have found no similar evaluation in the literature. METHOD: Among 1.000 schwannomas of the cerebello-pontine angle operated in Marseilles, France between July 1992 and March 2003, 9 have been diagnosed as originating from the VII. Criterias for this diagnosis are the involvement of the second or third portion of the VII nerve canal (7 patients) and/or peroperative observation during a previous microsurgery (2 patients). The rare facial palsy after vestibular schwannomas radiosurgery occurring usually before 18 Months have been considerated only the patients with more than 2 Years of follow-up (8 patients). RESULTS: Four of these patients had the experience of a previous spontaneous facial palsy one (3 patients) or several times (1 patient). A normal motor facial function was observed only in 2 cases before GKS (House 2 in 6 patients, House 3 in one). The follow-up was 2-7 Years for the evaluable patients. None of these have developed or worsened facial palsy, two have improved their preoperative facial palsy. To date, all tumors have been evaluated. The specificity and heterogeneity of this group of patients led us to develop an original classification in 4 anatomical types presenting different clinical and surgical difficulties. CONCLUSION: This first study demonstrates that radiosurgery allows treating these patients while preserving a normal motor facial function. Because of this advantage, GKS must be considered as a first option for all small to middle sized facial nerve schwannomas.

Adult↗
PubMed2004

[Perioperative targeting brachytherapy for lung cancer invading the chest wall].

We evaluated the efficacy of perioperative targeting brachytherapy for lung cancer invading the chest wall. Between 1998 and 2003, 7 patients underwent perioperative targeting brachytherapy for lung cancer invading the chest wall. There were 5 male and 2 female patients. The mean age was 63.3 years, with a range of 45 to 77 years. All patients underwent complete resection including the chest wall combined resection. During the operation, plastic afterloading catheters fixed on the Vicryl mesh at interval of 1 cm were placed on the site of chest wall resection. From the third to sixth day after the operation, 15 to 32 Gy of radiation was delivered over 3 or 4 days using a high dose rate remote afterloading system. The area targeted for brachytherapy was determined by a computed tomography (CT) scanner translator with a computer program for radiation planning. The median postoperative hospital stay was 35 days. Local recurrences were observed in 2 patients, but there was no evidence of recurrence in the margin of the resected chest wall. We believe that this short period of treatment and the low side effects enhances the quality of the patients. Prevention of local recurrence was achieved in short term follow-up.

Aged↗
PubMed2003

Tei index determined by tissue Doppler imaging in patients with pulmonary regurgitation after repair of tetralogy of Fallot.

The myocardial performance index (Tei index) determined by the pulsed Doppler method is a simple and noninvasive measurement for assessing global right ventricular (RV) function. This index can also be obtained by tissue Doppler imaging (TDI). The effects of significant pulmonary regurgitation (PR) on the determination of the Tei index by these two methods have not been investigated. We examined 15 patients (6.3 +/- 2.2 years) with significant PR after repair of tetralogy of Fallot (TOF) and 24 age-matched healthy children. Myocardial wall motion velocities at the tricuspid annulus were assessed during systole (Sa), early diastole (Ea), and late diastole (Aa) from a four-chamber view. Pulsed Doppler-Tei index and TDI-Tei index were measured as reported previously. The Tei index obtained by the pulsed Doppler method in TOF patients did not differ from that in normal children (0.30 +/- 0. 12 vs 0.32 +/- 0.07, p = not significant). TDI showed that TOF patients had significantly decreased Ea, Aa, and Sa velocities compared to those of normal children. Both isovolumic contraction time and isovolumic relaxation time in TOF patients were significantly longer than those in normal children (88 +/- 18 vs 62 +/- 23 msec and 46 +/- 11 vs 21 +/- 12 msec, respectively; p < 0.0001), although the duration of Sa did not differ between the two groups. Consequently, the Tei index as measured by TDI was significantly greater in TOF patients than in normal children (0.48 +/- 0.07 vs 0.30 +/- 0.07, p < 0.0001). The Tei index measured by the pulsed Doppler method is limited in its ability to assess RV function in patients with significant PR. However, the Tei index determined by TDI is a sensitive indicator of RV function in these patients, and it appears to be a promising new means of assessing global RV function in patients with significant PR.

Blood Flow Velocity↗
PubMed2003

Angle-resolved mapping of the fermi velocity in a quasi-two-dimensional organic conductor.

We demonstrate a new method for determining the Fermi velocity in quasi-two-dimensional (Q2D) conductors. Application of a magnetic field parallel to the conducting layers results in periodic open orbit quasiparticle trajectories along the Q2D Fermi surface. Averaging of this motion over the Fermi surface leads to a resonance in the interlayer microwave conductivity. The resonance frequency is simply related to the extremal value of the Fermi velocity perpendicular to the applied field. Thus, angle dependent microwave studies enable a complete mapping of the in-plane Fermi velocity. We illustrate the applicability of this method for the highly 2D organic conductor kappa-(BEDT-TTF)2I3.

Journal Article↗
PubMed2003

Inhibition of attachment of virions of Norwalk virus to mammalian cells by soluble histone molecules.

Viral infection is usually initiated by the binding of virus particles to specific receptor molecule(s) on the host cell surface. Blocking of this step prevents the following step, penetration into the cell. In the present study, we investigated the virus-cell interactions of virions of Norwalk virus (NV), a major etiological agent for viral diarrhea. We found that histone was an extremely strong NV-binding protein. Histone H1, a heterologous histone molecule, appeared to be able to interact not only with NV particles, but also with the cell surface. Histone H1 appeared capable of effectively preventing the attachment of NV to intestinal cells, but not of other viruses. No cytotoxic effects of histone were observed under the assay conditions. These results indicate that nonsecretory histone molecules may inhibit the attachment of viruses to cells like lactoferrins. Our results suggest that by searching virus-binding molecules, we might find antiviral agents, even for new viruses.

Animals↗
PubMed2003

Oral premedication with fentanyl may be a safe and effective alternative to oral midazolam.

BACKGROUND AND OBJECTIVE: Although midazolam is commonly given orally to infants and small children for premedication, the taste is sometimes unacceptable even when mixed with syrup. We tested the efficacy and safety of oral fentanyl compared with oral midazolam in a randomized open-label study. METHODS: Fifty-one children, aged 12-107 months and weighing 10-25 kg, were randomly assigned to fentanyl or midazolam treatment groups. Midazolam (5 mg) or fentanyl (0.1 mg) was given orally from a small bottle with a small orifice 30 min before transfer to the preoperative holding room. The excitation-sedation conditions of the patients were assessed before and after general anaesthesia. RESULTS: The preoperative scores did not differ significantly between the two groups. No major complications were observed in either group. Postoperative vomiting occurred in 5 of 27 (18.5%) patients treated with oral fentanyl and in none of 24 of those treated with midazolam. CONCLUSIONS: Oral administration of fentanyl 30 min before entrance to the holding room for an operation from a bottle with a small orifice is a premedication option for children between 1 and 8 yr of age.

Adjuvants, Anesthesia↗
PubMed2003

Near-infrared spectroscopy evaluated as a technique for estimating udder haemodynamics in the lactating cow.

Near-infrared spectroscopy (NIRS) that requires few compact instruments is a non-invasive and continuous method of monitoring haemodynamics in living organs. To assess the feasibility of using NIRS in evaluating the udder haemodynamics in six dairy cows, a probe component consisting of a light-emitting diode and a phototransistor was attached to the left side of the udder surface. Real-time variation of tissue haemodynamics was analysed and the data were transferred to the computer by way of a radiotelemetry system. On induction of temporary congestion by applying pressure with the hand pressed firmly against the left milk vein for 20 s, concentration of oxyhaemoglobin decreased throughout the 20-s duration of congestion, and concentration of deoxyhaemoglobin increased. A surge in blood volume was also observed from the beginning of congestion, then the volume attenuated to baseline. The data demonstrated that the reading seen on the monitor reflects the real-time status of the mammary gland. NIRS shows promise as a useful approach to physiological studies.

Animals↗
PubMed2003

Heterogeneity in residual function of MeCP2 carrying missense mutations in the methyl CpG binding domain.

Rett syndrome is a neurodevelopmental disorder with severe mental retardation caused by mutations in the MECP2 gene. Mutations in the MECP2 gene are also associated with other genetic disorders, including X linked mental retardation in males. Missense mutations identified so far are present primarily in the methyl CpG binding domain (MBD) of MECP2. Here, the functional significance of 28 MBD missense mutations identified in patients were analysed by transient expression of the mutant proteins in cultured cells. The effects of mutations were evaluated by analysis of the affinity of MeCP2 to pericentromeric heterochromatin in mouse L929 cells and on transcriptional repressive activity of MeCP2 in Drosophila SL2 cells. These analyses showed that approximately one-third (9/28) of MBD missense mutations showed strong impairment of MeCP2 function. The mutation of the R111 residue, which directly interacts with the methyl group of methyl cytosine, completely abolished MeCP2 function and mutations affecting beta-sheets and a hairpin loop have substantial functional consequences. In contrast, mutations that showed marginal or mild impairment of the function fell in unstructured regions with no DNA interaction. Since each of these mutations is known to be pathogenic, the mutations may indicate residues that are important for specific functions of MeCP2 in neurones.

Animals↗
PubMed2003

Induction of cyclooxygenase-2 in human endometrial stromal cells by malignant endometrial epithelial cells: evidence for the involvement of extracellularly regulated kinases and CCAAT/enhancer binding proteins.

We previously reported that human malignant endometrial epithelial cell conditioned medium (MECM) up-regulated cyclooxygenase (COX)-2 mRNA and protein levels in human normal endometrial stromal cells (ESC). Here we showed that pretreatment with a selective inhibitor of the extracellularly regulated kinase (ERK)1/2 signaling pathway blocked the MECM-induced COX-2 expression in ESC. Transient transfection assays indicated critical roles of a cAMP response element (CRE,-59/-53 bp) and a nuclear factor for interleukin (IL)-6 expression (NF-IL6) site (-132/-124 bp) in the regulation of basal and MECM-induced activity of COX-2 gene promoter in ESC. Employing electrophoretic mobility shift assays, we demonstrated that increased functional binding of CCAAT/enhancer binding protein (C/EBP)alpha, C/EBPbeta and upstream stimulatory factor-2 to the CRE and C/EBPalpha and C/EBPbeta to the NF-IL6 site were, at least in part, responsible for MECM-induced COX-2 expression in ESC. Moreover, overexpression of C/EBPalpha and C/EBPbeta significantly induced COX-2 promoter activity in ESC. Collectively, these results suggest that the basal and MECM-induced transcription of the COX-2 gene in ESC is regulated through a combination of the CRE and the NF-IL6 site by functional interactions of C/EBPalpha and C/EBPbeta.

Base Sequence↗
PubMed2003

[Surgical treatment for pulmonary metastasis from submandibular gland cancer].

We reviewed surgical result of 5 patients with pulmonary metastasis from submandibular gland cancer. Pathological diagnosis was adenoid cystic carcinoma in 2 patients, carcinoma in pleomorphic adenoma in 1, epidermoid carcinoma in 1, and mucoepidermoid tumor in 1. Disease free interval from resection of the primary lesion to diagnosis of pulmonary metastasis was ranging from 7 to 76 months. Lobectomy was performed in 2 patients and partial lung resection in 3. Three patients died of tumor recurrence 12 to 28 months after lung resection and 2 patients with a single metastatic lesion have survived as long as 42 and 150 months after the operation. This study suggests that surgical treatment may be effective for pulmonary metastasis, especially for a single metastatic lesion, from submandibular gland cancer.

Adult↗
PubMed2003

[Usefulness of mini loop retractor in video-assisted thoracic surgery].

We have developed a technique using a Mini Loop Retractor II and successfully performed video-assisted thoracoscopic surgery (VATS) in 32 patients. It is inserted into the pleural cavity through a skin puncture and a loop at its distal end is easily, and is freely adjustable in dimensions so that it can act as a retractor or holding forceps. Mini Loop Retractor II was very useful instruments in VATS.

Humans↗
PubMed2002

Regeneration of transformed verbena (Verbena x hybrida) by Agrobacterium tumefaciens.

Verbena (Verbena x hybrida), an important floricultural species, was successfully regenerated from stem segments on Murashige and Skoog's basal medium supplemented with thidiazuron and indole-3-acetic acid. A transformation system was developed using cvs. Temari Scarlet, Temari Sakura, Tapien Rose and TP-P2. Agrobacterium tumefaciens strain Agl0 harboring the sGFP gene was infected into stem segments. Transformation efficiency was improved by evaluating and manipulating the age of the plant material, the concentration of kanamycin in the medium during selection, and the length of the culture period in the dark. After 2-3 months of culture on the selection medium, GFP-positive shoots were obtained in all four of the cultivars tested. These shoots were successfully acclimated and set flowers within 2-3 months in a greenhouse. GFP was expressed in all of the organs including the floral parts. Stable genomic transformation was confirmed by Southern blot analysis. No morphological differences were observed between the transformed plants and their host plants.

Agrobacterium tumefaciens↗
PubMed2002

Characterization of virulence plasmid types in Rhodococcus equi isolates from foals, pigs, humans and soil in Hungary.

Rhodococcus equi isolates (204) obtained from foals (lung abscesses, lymph nodes, nasal discharge, rectal swabs) bred in 15 studs located throughout Hungary, isolates from soil samples, lymph nodes of pigs and from lesions of human patients were examined to determine genotypic diversity of virulence-associated plasmids. Isolates were tested for the presence of 15-17 kDa virulence-associated protein antigen (VapA) and 20k Da (VapB) genes by polymerase chain reaction (PCR). Plasmid DNAs were isolated and analysed by digestion with restriction endonucleases for estimation of size and comparison of polymorphisms. Of 146 clinical isolates from foals in 15 studs, 129 (88.3%) gave positive results for the VapA gene, showing a 564 bp product of the expected size in the PCR amplification. Of the 129 clinical isolates from foals, 123 contained an 85 kb type I plasmid and the remaining six contained an 87 kb type I plasmid. Of 48 soil isolates from two horse studs, 26 (54.2%) were positive for VapA gene and contained an 85 kb type I plasmid. Of three pig isolates, one was positive for VapA gene and contained an 85 kb type I plasmid, and the remaining two were positive for the VapB gene, showing a 827 bp product of the expected size in the PCR amplification and were R. equi of intermediate virulence which contained a 95 kb type S5 plasmid. Of the seven human isolates, five were positive for VapB gene by PCR, these were R. equi of intermediate virulence, which contained a 95 kb type S5 plasmid. These results revealed that virulent R. equi strains harbouring a virulence plasmid of 85 kb type I or 87 kb type I, which have been found in clinical isolates from Europe and North and South America, are widespread in Hungary. Furthermore, same intermediately virulence plasmid type was found in both human and pig isolates.

Actinomycetales Infections↗