Biomedical subjects

T Sugahara

Publications and source records attributed to T Sugahara.

At least 55 records · Page 3Linked to original sources

PubMed2000

Chromosome translocation in residents of the high background radiation areas in southern China.

We performed a cytogenetical study using chromosome painting analysis on 9 residents of the naturally high background radiation areas (HBRA) and 8 residents of the control areas in southern China. The estimated dose (air kerma) of each resident measured by an electric pocket dosimeter showed 2.20-4.23 mGy/year in HBRA and 0.56-0.70 mGy/year in the control areas. A total of 14,096 cells (1,566 cells/case) in the former and 17,522 cells (2,190 cells/case) in the latter were analyzed. Children, both in HBRA and in the control areas, had translocations at low frequencies. The frequency of translocations among elder individuals varied widely and it was not possible to detect dose effect although it was detected in dicentrics. The effect of radiation on the induction of chromosome aberrations, which have a statistically potential risk of causing malignant or congenital diseases, seems to be less significant than those of metabolic factors and/or mutagenic agents (excluding radiation) even in HBRA in China.

Aged↗

PubMed2000

Dose measurement, its distribution and individual external dose assessments of inhabitants in the high background radiation areas in China.

As a part of the China-Japan cooperative research on natural radiation epidemiology, we have carried out a dose-assessment study to evaluate the external exposure to natural radiation in the high background radiation areas (HBRA) of Yangjiang in Guangdong province and in the control areas (CA) of Enping prefecture since 1991. Because of the difficulties in measuring the individual doses of all inhabitants directly by personal dosimeters, an indirect method was applied in which the exposed individual doses were estimated from the environmental radiation doses measured by survey meters and the occupancy factors of each hamlet. We analyzed the dose in the hamlets and the variation in the occupancy factors to obtain the parameters of dose estimation on the inhabitants in selected hamlets; Madi and several hamlets of different dose levels in HBRA and Hampizai hamlet in CA. With these parameters, we estimated individual dose rates and compared them with those obtained from direct measurement using dosimeters carried by selected individuals. The results obtained are as follows. 1) The environmental radiation doses are influenced by the natural radioactive nuclide concentrations in building materials, the age of the building and the arrangement of the houses in a hamlet. There existed a fairly large and heterogeneous distribution of indoor and outdoor environmental radiations. The indoor radiation doses were due to exposure from the natural radioactive nuclides in the building materials and were about two times as large as the outdoor radiation doses. The difference between indoor and outdoor doses was not observed in CA. 2) The occupancy factor was influenced by the age of individuals and by the season of the year. The occupancy factor was higher for infants and aged individuals than for other age groups. This lead to higher dose rates of exposure to those age groups. 3) A good correlation was observed between the dose assessed indirectly and that measured directly and the correlation factor was 0.97.

Background Radiation↗

PubMed2000

Comparison between palatal configurations in UCLP infants with and without a Hotz plate until four years of age.

OBJECTIVE: To evaluate the efficacy of presurgical orthopedic treatment three dimensionally, we previously developed a novel measuring system and described the efficacy of the treatment until 18 months of age. The aim of this study was to compare palatal configuration in complete unilateral cleft lip and palate (UCLP) infants fitted with a Hotz plate to those without it until four years of age using the same measuring system. PATIENTS: Twenty complete UCLP infants were divided into two groups. A Hotz plate was used with 12 patients who first visited our clinic from January 1990 to March 1992 and was not used with an additional eight patients who first visited from April 1992 to July 1993. MAIN OUTCOME MEASURES: Palatal casts taken from birth until four years of age were measured three dimensionally and were compared between the two groups. RESULTS AND CONCLUSIONS: The width of the palate was larger in the group with a Hotz plate than in the group without it at four years of age. No difference was observed between the anteroposterior distance of the palate in the two groups at four years of age. Similarly, the alveolar arch form did not differ between the two groups. The degree of curvature of the palatal surface was smaller in the group with a Hotz plate than in the group without it. These data were similar to data obtained at 18 months of age.

Child, Preschool↗

PubMed2000

Evaluation of dural sinus invasion and extension of extra-axial intracranial tumors. The advantages of a high-resolution postcontrast 3-D gradient-echo technique.

OBJECTIVE: To assess the usefulness of a postcontrast 3-D Fourier transform (3DFT) gradient-echo (GRE) technique in dural sinus invasion and extension of extraaxial intracranial tumors in comparison with a conventional spin-echo (SE) technique. MATERIAL AND METHODS: Fourteen consecutive patients with 15 extra-axial tumors in contiguity with the dural sinus, including 14 meningiomas and 1 adenoid cystic carcinoma, underwent postcontrast T1-weighted SE and GRE MR studies. Detectability of dural sinus invasion and extension was evaluated using two sequences by two neuroradiologists in a blinded manner and compared with surgical results. Quantitative analysis was also performed to calculate the contrast-to-noise ratio (CNR) between lesion and dural sinus on SE and GRE images. The data were analyzed statistically using a matched paired t-test. RESULTS: In the qualitative evaluation, the detectability of dural sinus invasion in 3DFT-GRE images was superior to that using SE images. The mean CNR for all lesions was 3.86 on SE images and 5.63 on 3DFT-GRE images (p = 0.03). CONCLUSION: For evaluation of dural sinus invasion and the extension of extra-axial tumors, postcontrast 3DFT-GRE MR images were superior to conventional SE images.

Adult↗

PubMed2000

Posttherapeutic intraaxial brain tumor: the value of perfusion-sensitive contrast-enhanced MR imaging for differentiating tumor recurrence from nonneoplastic contrast-enhancing tissue.

BACKGROUND AND PURPOSE: Differentiation of tumor recurrence from treatment-related changes may be difficult with conventional MR imaging when newly enhancing lesions appear. Our aim was to determine the value of perfusion-sensitive contrast-enhanced MR imaging for differentiating recurrent neoplasm from nonneoplastic contrast-enhancing tissue. METHODS: Twenty patients in whom new enhancing lesions developed within irradiated regions were examined prospectively with perfusion-sensitive contrast-enhanced MR imaging. Twelve of them also underwent thallous chloride Tl 201 single-photon emission tomography (201Tl-SPECT). Normalized relative cerebral blood volume (rCBV) ratios and thallium indexes were evaluated to determine whether the new enhancing lesions were recurrent or not. Five instances of tumor recurrence and one of radiation necrosis were verified histologically; in the others, tumor recurrence was distinguished by lesions that progressively increased in size on serial MR examinations over at least 5 months, and nonneoplastic contrast-enhancing tissue was distinguished by lesions that disappeared or decreased in size on serial MR studies over at least 9 months. RESULTS: When normalized rCBV ratios were higher than 2.6 or lower than 0.6, enhancing lesions were either recurrent (n = 5) or nonneoplastic contrast-enhancing tissue (n = 3), respectively. All nonneoplastic contrast-enhancing tissue had a low thallium index, whereas three of four recurrent lesions had a high index. CONCLUSION: An enhancing lesion with a normalized rCBV ratio higher than 2.6 or lower than 0.6 may suggest tumor recurrence or nonneoplastic contrast-enhancing tissue, respectively. In these cases, further examination with 201Tl-SPECT may not be necessary. However, when the normalized rCBV ratio is between 0.6 and 2.6, 201Tl-SPECT may be useful in making the differentiation.

Adolescent↗

PubMed1999

Usefulness of diffusion-weighted MRI with echo-planar technique in the evaluation of cellularity in gliomas.

The purpose of this study was to evaluate the utility of diffusion-weighted magnetic resonance imaging (MRI) with echo-planar imaging (EPI) technique in depicting the tumor cellularity and grading of gliomas. Twenty consecutive patients (13 men and 7 women, ranging in age from 13 to 69 years) with histologically proven gliomas were examined using a 1.5 T superconducting imager. Tumor cellularity, analyzed with National Institutes of Health Image 1.60 software on a Macintosh computer, was compared with the minimum apparent diffusion coefficient (ADC) and the signal intensity on the T2-weighted images. The relationship of the minimum ADC to the tumor grade was also evaluated. Tumor cellularity correlated well with the minimum ADC value of the gliomas (P = 0.007), but not with the signal intensity on the T2-weighted images. The minimum ADC of the high-grade gliomas was significantly higher than that of the low-grade gliomas. Diffusion-weighted MRI with EPI is a useful technique for assessing the tumor cellularity and grading of gliomas. This information is not obtained with conventional MRI and is useful for the diagnosis and characterization of gliomas.

Adolescent↗

PubMed1999

3D TOF turbo MR angiography for intracranial arteries: phantom and clinical studies.

This work investigated whether turbo magnetic resonance angiography (MRA) can replace conventional MRA in screening examination of intracranial arteries. A phantom was used to evaluate the effect of the zero-filling interpolation (ZFI) technique on spatial resolution and partial volume effect. Thirty-one consecutive patients underwent both turbo MRA with a slice thickness of 0.7 mm (data were measured as 1.33 mm sections) and conventional MRA with 1.0 mm sections. In the phantom studies, ZFI did not improve the spatial resolution, but the partial volume effect was somewhat reduced. In the clinical evaluation, turbo MRA showed better signal-to-noise and contrast-to-noise ratios of the intracranial major vessels than conventional MRA. The lesions included cerebral aneurysms less than 3 mm in diameter, occlusive vascular disease, arteriovenous malformations, and arteriovenous fistulas. These were all depicted on both turbo MRA and conventional MRA. Turbo MRA is a useful screening procedure because of its capability of delineating lesions in approximately half the usual imaging time. J. Magn. Reson. Imaging 1999;10:939-944.

Adult↗

PubMed1999

Development of a 3-D measurement and evaluation system for facial forms with a liquid crystal range finder.

A 3-D measurement and evaluation system for facial forms was developed with a liquid crystal range finder (LCRF). Its mechanical resolution was approximately/= 0.4 mm, and it was capable of measuring >30000 points from the entire facial surface in one second. An original program was developed to identify facial landmarks using not only linear distances, but also 3D-curvatures and discriminant analysis of the RGB data. With this program, the 3-D identification of anthropometrical points became possible with high accuracy. Due to the rapidity of the measuring apparatus and morphological evaluation system, it became possible to analyze the facial forms of infants such as cleft lip patients three dimensionally, without any sedation. Therefore, 97 normal infants (mean: 4.3 months of age) were measured and analyzed with this system. A cleft lip infant was measured and compared with the normal infants before and after cleft lip surgery, and the improved points and remaining problems were clearly recognized.

Cephalometry↗

PubMed1999

Levels of human defensin-1, an antimicrobial peptide, in saliva of patients with oral inflammation.

OBJECTIVE: The purpose of this study was to investigate the presence of an antimicrobial peptide, human defensin-1, in the saliva of patients with oral inflammation. STUDY DESIGN: Whole saliva samples were collected from patients with oral inflammation and from healthy volunteers. Human defensin-1 in saliva was isolated and purified by reversed-phase high-performance liquid chromatography. The amino acid sequence and molecular weight of defensin-1 were determined. The concentration of defensin-1 in saliva was quantified by high-performance liquid chromatography. Serum C-reactive protein concentration was measured by particle-enhanced turbidimetric immunoassay. RESULTS: The salivary defensin-1 concentration was significantly higher in patients with oral inflammation than in healthy volunteers; furthermore, in patients with oral inflammation, the concentration was significantly higher before treatment than after treatment. In the patients with oral inflammation, there was a strong positive correlation between salivary defensin-1 concentration and serum C-reactive protein concentration. CONCLUSIONS: The findings suggest that defensin-1 in saliva may be a convenient marker of inflammation associated with oral disease.

Adult↗

PubMed1999

Experimental study of bone formation from autogenous periosteal graft following insulin-like growth factor I administration.

The present study evaluates the effect of insulin-like growth factor I (IGF-I) administration on bone formation following grafted periosteum. Twenty-four Japanese white rabbits were randomly assigned into one IGF-I administered group (1 mg for 14 days) and a second control group. Grafted periosteum taken from the tibia was placed under the submandibular muscles. At 14, 21, and 28 days following the operation, the grafted periosteum was extirpated and examined. Throughout all stages of the experiment, active bone formation was confirmed histologically and radiographically in both control and experimental groups. In addition, a micro-CT scan was used to observe three-dimensional micro structures in newly formed bone and to measure the trabecular bone thickness as a marker of bone development. As a result, a significant increase in bone formation in the IGF-I group was observed when compared with the findings in the control group. Trabecular bone thickness in the IGF-I group was significantly greater when compared with the control group at 14 days and 21 days following grafting (P < 0.01). At 28 days following grafting, there were no significant differences, suggesting that administration of IGF-I may play an important role in inducing bone formation from grafted periosteum in the early stages.

Animals↗

PubMed1999

Computer aided three-dimensional analysis of nostril forms: application in normal and operated cleft lip patients.

The appearance of the nostril in cleft lip patients is very important in the subjective assessment of naso-labial forms and patient satisfaction. To improve the outcome of plastic surgery, a computer aided diagnostic system was developed. Facial forms were measured with a three-dimensional optical scanner (Ogis Range Finder RFX-IV) XYZ coordinates (256x240) and RGB (red, green, blue) image (512x480) data sets were then obtained with the apparatus. The nostril area was determined by discriminant analysis of the RGB data, and the landmarks of the nostril were extracted under geometric conditions. To assess the reliability of this technique with head inclination, five volunteers were measured in seven postures. Landmark stability was within approximately 1 mm when the Frankfort plane was 45-60 degrees. Subsequently, this system was applied to two cleft lip patients who had undergone a secondary nasal correction. For control data, 37 healthy adults (22 males and 15 females) were measured in the same manner. Nasal asymmetry in the unilateral case and wide and flat nostrils in the bilateral case were greatly improved after surgery. Conversely, the volume of the nasal tip decreased. This system was a great help in the diagnosis of nostril abnormalities.

Adolescent↗

PubMed1999

Value of dynamic susceptibility contrast magnetic resonance imaging in the evaluation of intracranial tumors.

The degree of tumor malignancy generally correlates to tumor grade, and the direct measurement of tumor vasculature is desired. Dynamic susceptibility contrast magnetic resonance imaging can provide relative cerebral blood volume and, therefore, is one of the most reliable methods to evaluate tumor vasculature in vivo. Tumor vessel size is extremely variable due to complex tumor angiogenesis, and the gradient-echo echo-planar imaging (GE-EPI) technique, which is sensitive to the total vascular bed, is well suited for this purpose. As many studies have shown, dynamic susceptibility contrast magnetic resonance imaging is more useful for grading glioma than conventional magnetic resonance imaging. We found that this technique can also provide supplementary information to differentiate between malignant lymphoma and glioma because the absence of tumor neovascularization of malignant lymphoma leads to low rCBV, which is in contrast to those of malignant gliomas. Indeed, this technique can be used for the differentiation of extra-axial tumors such as between meningioma and neurinoma. Recently, this technique has been focused toward determining the stereotactic biopsy site, monitoring the embolization of effect in meningioma, or evaluation of treatment effects after radiation therapy. However, the value of tumor rCBV is affected by many conditions such as the T1 relaxivity effects of gadolinium in the extravascular space. To establish the usefulness of this technique, further examination will be needed.

Adult↗

PubMed1999

A case of Pai syndrome.

A fourth patient suspected of having Pai syndrome is described. The female baby had a median cleft of the upper lip, a polypoid skin mass in the right nostril, and a conjunctival lipoma in the right eye. A median alveolar cleft was in the oral cavity. The polypoid skin mass was attached to the nasal septum, and a histologic examination disclosed mature adipose tissue with normal skin and no cartilaginous tissue. A computed tomographic scan revealed a lipoma of the corpus callosum. However, the patient was neurologically normal, and her electroencephalogram was also normal. Her growth and development have been within normal limits, and no convulsions have occurred.

Brain Neoplasms↗

PubMed1999

Defensin-1, an antimicrobial peptide present in the saliva of patients with oral diseases.

OBJECTIVES AND DESIGN: A preceding paper has noted a detection of defensin-1 (HNP-1), a peptide with antimicrobial and cytotoxic properties, in the saliva of patients with oral squamous cell carcinoma. The present study deals with the presence of HNP-1 in the saliva of patients with various oral diseases. METHODS: Whole saliva samples were obtained from the patients. HNP-1 in the saliva was isolated and purified by HPLC and the amino acid sequence of the peptide was determined. The molecular weight of HNP-1 was measured by mass spectrometry. The concentration of HNP-1 in saliva was determined by comparing the height of eluted HNP-1 with that of a synthetic HNP-1 standard. RESULTS: The concentrations of HNP-1 in the saliva of patients with oral lichen planus (n = 5), leukoplakia (n = 4), and glossitis associated with iron deficiency (n = 4) were 8.3 +/- 4.3 micrograms ml-1, 13.2 +/- 7.9 micrograms ml-1, and 11.4 +/- 4.9 micrograms ml-1, (mean +/- s.d.), respectively. These concentrations were significantly higher than those in healthy subjects (0.8 microgram ml-1) (P < 0.01). In contrast, salivary HNP-1 concentrations in patients with glossodynia (n = 4) and oral discomfort (n = 4) were similar to those in healthy subjects. CONCLUSIONS: Since HNP-1 is a non-specific defensive peptide present in neutrophils, it may play an important role in the protection against diseases such as oral lichen planus, leukoplakia, and glossitis associated with iron deficiency.

Adult↗

PubMed1999

Brain lesions: when should fluid-attenuated inversion-recovery sequences be used in MR evaluation?

PURPOSE: To compare qualitatively and quantitatively the contrast of brain lesions detected with fluid-attenuated inversion-recovery (FLAIR) and intermediate-weighted sequences at magnetic resonance (MR) imaging. MATERIALS AND METHODS: In this prospective study, 47 patients suspected of having a brain lesion underwent MR imaging with FLAIR, intermediate-weighted, and T2-weighted sequences. Qualitative assessment was performed of lesion conspicuity, detection, overall image artifact, and additional clinical information. Contrast and contrast-to-noise ratio (CNR) were calculated between lesions and the normal brain or cerebrospinal fluid (CSF). RESULTS: FLAIR images were equal to intermediate-weighted images for overall lesion conspicuity and detection but were associated more often with image artifacts. Lesion-to-background contrast was significantly higher on FLAIR than on intermediate-weighted images. FLAIR images failed to demonstrate multiple sclerosis (MS) plaques located in the basal ganglia and brain stem. CONCLUSION: Although FLAIR images provided additional information in some cases, they did not have distinct advantages over intermediate-weighted images. When cases of MS are evaluated, intermediate-weighted images are preferable to FLAIR images. Except in cases of MS, either FLAIR or intermediate-weighted sequences should be added to T2-weighted sequences at MR imaging.

Adolescent↗

PubMed1999

Cancer mortality among radiological technologists in Japan: updated analysis of follow-up data from 1969 to 1993.

A retrospective cohort study was conducted for 12,195 male radiological technologists who received the occupational exposure to low dose radiation over a long term. A total of 1,097 deaths including 435 from cancer were ascertained by Koseki and death certificates from 1969 to 1993. Cancer mortality among the study population was basically compared with that of whole Japanese men. The significant low SMRs were obtained for all cancers, stomach and lung cancer partly due to Healthy Worker Effect, unlike the results of the early reports with some inappropriateness in the methods. Apparent high risks of lymphatic and hematopoietic cancers were observed, although none of site-specific cancers revealed the statistically significant increase. For these cancers, the SMRs among old sub-cohort were somewhat higher than those of young sub-cohort, whereas similar SMRs for solid cancer were obtained between the two sub-cohorts. The SMR for leukemia reached statistically significant level of 1.75 (95% CI: 1.07-2.71) when using whole professional and technical workers as a standard population. The study results might suggest that the chronic exposure to low-dose radiation enhanced the risk of lymphatic and hematopoietic cancers.

Adult↗

PubMed1999

[Differential diagnosis of astrocytic tumors].

Primary brain tumors are subdivided into two basic groups: tumors of neuroglial origin (so-called gliomas) and nonglial tumors. The most common glioma is astrocytoma. In this review article, we describe the differential diagnosis of benign and malignant astrocytic tumors (astrocytoma, anaplastic astrocytoma, and glioblastoma) on conventional MR images. Regardless of the degree of histopathologic differentiation or anplasia, all infiltrating gliomas are clinically malignant. Therefore, it is important to diagnose the infiltrative nature of the tumors on MR images. Characteristic MR findings including signal intensity, contrast enhancement, and localization of the astrocytic tumors are discussed.

Adult↗

PubMed1999

Detection of intracranial hemorrhage with susceptibility-weighted MR sequences.

BACKGROUND AND PURPOSE: Detection of hemorrhage is important in the diagnosis and management of a variety of intracranial diseases. We evaluated the sensitivity of the following sequences for depicting chronic hemorrhagic foci associated with susceptibility dephasing: gradient-recalled echo (GRE) imaging, GRE-type single-shot echo-planar imaging (GRE-EPI), spin-echo-type single-shot echo-planar imaging (SE-EPI), turbo spin-echo (TSE) imaging, half-Fourier single-shot turbo spin-echo (HASTE) imaging, and segmented HASTE (s-HASTE) imaging. To our knowledge, no previous comparison has been made with these techniques in the same patient. METHODS: Fifty patients with suspected chronic hemorrhage were examined prospectively with the above six sequences. Contrast-to-noise ratio (CNR), sensitivity to detection of lesions, conspicuity of internal architecture, and sensitivity to small hemorrhagic foci were evaluated. RESULTS: Hemorrhagic foci were found in 35 patients. The CNR of the GRE, GRE-EPI, SE-EPI, TSE, s-HASTE, and HASTE sequences was 30.9, 23.7, 3.6, 6.1, -29.3, and -13.1, respectively; the number of small hemorrhagic foci detected was 85, 96, 44, 22, two, and one, respectively, for the supratentorial white matter; 70, 40, 19, four, zero, and zero, respectively, for the supratentorial cortical/subcortical region; and 73, 50, 26, 37, zero, and zero, respectively, for the infratentorial/skull-base region. CONCLUSION: The GRE sequence was best for detecting susceptibility dephasing associated with chronic intracranial hemorrhage. GRE-EPI, while comparable to GRE in the supratentorial compartment, was reduced in its sensitivity near the skull base, and may be used as an alternative to GRE in uncooperative, unsedated, pediatric, or claustrophobic patients. SE-EPI should not be used in screening for intracranial hemorrhage.

Adolescent↗