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Biomedical subjects

R Baba

Publications and source records attributed to R Baba.

At least 19 recordsLinked to original sources
PubMed2004

Using a flat-panel detector in high resolution cone beam CT for dental imaging.

OBJECTIVES: Cone beam CT (CBCT) requires a two-dimensional X-ray detector. In the several CBCT systems developed for dental imaging, detection has been by the combination of an X-ray image intensifier and charge-coupled device (CCD) camera. In this paper, we propose a new CBCT system in which the detector is of the flat-panel type and evaluate its performance in dental imaging. METHODS: We developed a prototype CBCT that has a flat-panel-type detector. The detector consists of a CsI scintillator screen and a photosensor array. First, the flat panel detector and image intensifier detector were compared in terms of the signal-to-noise ratio (SNR) of projected images. We then used these data and a theoretical formula to evaluate noise in reconstructed images. Second, reconstructed images of a bar pattern phantom were obtained as a way of evaluating the spatial resolution. Then, reconstructed images of a skull phantom were obtained. RESULTS: The SNR of the developed system was 1.6 times as high as that of a system with an image intensifier detector of equal detector pitch. The system was capable of resolving a 0.35 mm pattern and its field of view almost completely encompassed that of an image intensifier detector which is used in dentomaxillofacial imaging. The fine spatial resolution of the detector led to images in which the structural details of a skull phantom were clearly visible. CONCLUSIONS: The system's isotropically fine resolution will lead to improved precision in dental diagnosis and surgery. The next stage of our research will be the development of a flat panel detector system with a high frame acquisition rate.

Algorithms↗
PubMed2001

Characterization of the Chromophore Orientation of Rhodamine B Amphiphiles in Langmuir-Blodgett Monolayers.

SHG (second harmonic generation) interferometry and linear dichroism measurements were applied to the characterization of Langmuir-Blodgett monolayers composed of rhodamine B derivatives on hydrophilic fused silica substrates. When excited with a Nd-YAG laser, the contribution of dimeric species composed of rhodamine B chromophores to the nonlinear optical behavior was large, even though the relative concentration of the dimers was small. This implies the formation of noncentrosymmetrically oriented dimers with a relatively higher nonlinear molecular susceptibility, beta. Therefore, a unique phenomenon was observed; that is, the relative phase of the SH light shifted depending on the incident light polarization (p and s). In addition, it was found that the relatively standing up orientation was favored for the dimer, while a strongly tilted orientation was favored for the monomer. Copyright 2001 Academic Press.

Journal Article↗
PubMed2000

Hypoplastic basement membrane of the lens anlage in the inheritable lens aplastic mouse (lap mouse).

Adult homozygous lap mice show various eye abnormalities such as aphakia, retinal disorganization, and dysplasia of the cornea and anterior chamber. In the fetal eye of a homozygous lap mouse, the lens placode appears to develop normally. However, the lens vesicle develops abnormally to form a mass of cells without a cavity, and the mass vanishes soon afterward. Apoptotic cell death is associated with the disappearance of the lens anlage. We examined the basement membranes of the lens anlage of this mutant by immunohistochemical methods under light microscopy using antibodies against basement membrane components of the lens anlage, type IV collagen, fibronectin, laminin, heparan sulfate proteoglycan, and entactin and by transmission electron microscopy. Immunohistochemistry showed the distribution and intensity of antibody binding to the lens anlage to be almost the same for each these antibodies regardless of the stage of gestation or whether the anlagen were from normal BALB/c or lap mice. Thus, positive continuous reactions were observed around the exterior region of the lens anlage from day 10 of gestation for type IV collagen, fibronectin, laminin, heparan sulfate proteoglycan antibodies, and at least from day 11of gestation for entactin antibody. The basement membrane lamina densa of both normal and lap mice was shown by electron microscopy to be discontinuous at days 10 and 10.5 of gestation. However, by day 11 the lamina densa was continuous in the lens anlagen of normal mice but still discontinuous in the lap mice. By day 12 of gestation, the lamina densa had thickened markedly in normal mice, whereas in lap mice it remained discontinuous and its thinness indicated hypoplasia. These results indicate that, while all basement components examined are produced and deposited in the normal region of the lens anlage in the lap mouse, the basement membrane is, for some reason, imperfectly formed. The time at which hypoplasia of the basement membrane was observed in this mutant coincided with the stage during which apoptosis in the lens anlage occurred. This result may indicate a possibility of the relationship between the basement membrane and apoptosis in this mutant.

Animals↗
PubMed2000

[An electron microscopic study of the relation between epithelial cell damage and eosinophilia in the nasal mucosa of patients with nasal allergy].

To determine the relationship between epithelial damage and eosinophilia in the nasal mucosa of patients with nasal allergy, we examined the nasal mucosa (obtained by surgery) from 74 patients with allergic rhinitis, using light and electron microscopy. The extent of eosinophilia correlated significantly to grades of epithelial damage and torn tight junctions of the epithelial cells. No significant relationships were found between the severity of nasal symptoms and the extents of eosinophilia or grades of torn tight junctions of the epithelial cells. More than 50% specific granules in eosinophils in the allergic nasal mucosa showed normal findings. There were no significant relationships between the extent of eosinophil degranulation and grades of epithelial damage. Based on our results, the release of tubular vesicular structures from the eosinophil granule may be one form of eosinophil degranulation in the nasal mucosa of patients with nasal allergy.

Adult↗
PubMed1999

Oxygen uptake efficiency slope as a useful measure of cardiorespiratory functional reserve in adult cardiac patients.

In this study we aimed to elucidate the validity and usefulness of the oxygen uptake efficiency slope (OUES) in the evaluation of adult cardiac patients. Cardiopulmonary exercise tests were performed on a treadmill by 50 adult patients with chronic heart failure. The OUES was calculated from data for the first 75%, 90%, and 100% of exercise duration. The OUES is derived from the following equation: VO(2)=ax logV(E)+b, where VO(2) is oxygen uptake (ml/kg/min), V(E) is minute ventilation (l/kg/min), and the constant "a" represents OUES. We also determined the ventilatory anaerobic threshold (VAT). The correlation coefficient of the logarithmic curve-fitting model was [mean (SD)] 0.986 (0.009). The OUES could be used to discriminate effectively between New York Heart Association functional classes (P < 0.001). OUES and maximum VO(2) were significantly correlated (r=0.78, P < 0.01). Agreement between the OUES values for the first 90%, 75%, and 100% of the exercise was excellent (intraclass correlation coefficient = 0.99). Our results suggest that OUES is applicable to adult cardiac patients as an objective, effort-independent estimation of cardiorespiratory functional reserve.

Aged↗
PubMed1999

Role of the oxygen uptake efficiency slope in evaluating exercise tolerance.

OBJECTIVE: To investigate the interprotocol agreement of oxygen uptake efficiency slope (OUES). METHODS: 16 Japanese children and adolescents (10 boys and six girls) underwent two sessions of maximal exercise testing according to the following two treadmill protocols: the standard Bruce protocol and the rapidly increasing staged (RIS) protocol. Maximal oxygen uptake (VO2max), the ventilatory anaerobic threshold (VAT), and the OUES were obtained from the gas analysis data. Agreement between the protocols was tested by means of the Bland-Altman method. RESULTS: Interprotocol agreement was excellent for the OUES (limit of agreement, -18% to 17% of the mean value), slightly less good for VO2max (limit of agreement, -20% to 24% of the mean value), and poor for the VAT (limit of agreement, -31% to 31% of the mean value). CONCLUSION: These results confirm the clinical usefulness of the OUES as a measure of evaluating exercise tolerance in the paediatric population.

Adolescent↗
PubMed1999

The alteration of nasal resistance before and after local exposure to heated aerosol in perennial allergic rhinitis.

To determine the patho-physiological effects of heated vapour to the normal or allergic nasal mucosa, we measured the nasal resistance before and after a 10 min. exposure of hyperthermal (43.0 degrees C) aerosol to the nasal mucosa in normal subjects and perennial allergic rhinitis patients. In the allergic patients the mean nasal resistances after hyperthermal stimulation were significantly higher than those resistances without stimulation, both in expiration or inspiration. No significant differences of nasal resistances in normal individuals during the whole schedule with and without heated aerosol stimulation were found on expiration or inspiration. The local heated aerosol exposure increases the nasal resistance in nasal allergic patients while in normal subjects no changes were found, and the reaction may have arisen from a non-specific hypersensitivity of the susceptible allergic nasal mucosa.

Administration, Inhalation↗
PubMed1999

Reproducibility of the oxygen uptake efficiency slope in normal healthy subjects.

BACKGROUND: To elucidate the intertest agreement of the oxygen uptake efficiency slope (OUES) in comparison with those of the maximal oxygen uptake (VO2max) and the ventilatory anaerobic threshold (VAT). METHODS EXPERIMENTAL DESIGN: A comparative study. SETTING: Institutional practice. A total of 19 healthy volunteers underwent two sessions of maximal exercise testing with an interval of no more than 7 days. The testing was conducted on a cycle ergometer with the work rate increased by either 20, 30, or 40 Watts (W)/min so that the subject would reach exhaustion within 9 to 12 min of exercise. VAT was defined as the level of oxygen uptake (VO2) at which either an increase in the ventilatory equivalent for oxygen without a concomitant increase in the ventilatory equivalent for carbon dioxide or a change in the slope of the linear relationship between carbon-dioxide production (VCO2) and VO2 occurred. OUES was determined by the following equation: VO2 = a log VE + b, where VE was minute ventilation and "a" was the OUES. Intertest reproducibility was assessed by coefficient of repeatability (COR). RESULTS: The intertest reproducibility of VO2max and OUES were excellent (COR = 570 ml/min [16%] and 740 [20%], respectively). VAT showed poor agreement between the two tests (COR = 650 ml/min [31%]). CONCLUSIONS: Results show that OUES is reproducible and reliable, supporting the clinical usefulness of this index.

Adult↗
PubMed1998

Apoptosis in the lens anlage of the heritable lens aplastic mouse (lap mouse).

Adult homozygous lap mice show various eye abnormalities, such as aphakia, retinal disorganization, and dysplasia of the cornea and anterior chamber. In the fetal eye of a homozygous lap mouse, the lens placode seems to develop normally. However, the lens vesicle progresses abnormally to form a mass of cells without a cavity, and the mass vanishes soon afterward. We examined cell death in the lens anlage of this mutant. The lens anlagen of homozygous lap and normal mice from days 10 to 12 of gestation were observed by light microscopy after DNA end-labeling by immunohistochemistry and by transmission electron microscopy. By light microscopy, a slight frequency of cell death was detected in the lens anlage encircling the surface ectoderm and in the anlage or in the anlage of both homozygous lap mice and normal mice at day 10 of gestation. Cell death was seen in the lens anlage encircling the surface ectoderm in the normal mouse and sporadically in the anlage of the homozygous lap mouse at day 10.5 of gestation. Cell death was visible at the area of the lens vesicle attached to the surface ectoderm and encircling the surrounding surface ectoderm in the normal mouse, and in the lens anlage encircling the surface ectoderm and the apex areas of the lens anlage in the homozygous lap mouse at day 11 of gestation. At day 12 of gestation, almost no cell death was observed in the lens anlage of the normal mouse. However, extensive areas of cell death were still seen in the lens anlage at its apex, at the inner region, and encircling the surface ectoderm in the homozygous lap mouse. Electron microscopic observation showed that the dead cells observed in the lens anlagen by light microscopy in normal and lap mice are the result of apoptosis. In lap mice, cells with cytoplasmic condensation were observed mainly at days 10 and 10.5 of gestation. Many apoptotic bodies which had been phagocytosed by adjacent cells were seen predominantly at day 11 of gestation. At day 12 of gestation, apoptotic bodies phagocytosed by adjacent cells, which were seen at day 11, were still predominant, but there were more apoptotic bodies per cell and more digested apoptotic bodies than at day 11. These results indicate that cell death, resulting from apoptosis is involved in the disappearance of the lens anlage of lap mice.

Animals↗
PubMed1998

Ventilatory control during exercise in normal children.

We investigated the relation between age and respiratory control during exercise in 80 children aged 6.4-17.6 y (42 male, age, 11.6 +/- 3.3 y; body weight, 41.3 +/- 14.7 kg; and 38 female, age, 12.6 +/- 2.7 y; body weight, 42.5 +/- 9.3 kg). Exercise tests were performed on a treadmill after a standard symptom-limited Bruce protocol. Data were analyzed separately for boys and girls. At rest and at peak exercise, the ratio of minute ventilation to carbon dioxide production (VE/VCO2), the ratio of effective alveolar ventilation to carbon dioxide production (VA/VCO2), the ratio of pulmonary dead space to tidal volume (Vd/Vt), and arterial PCO2 (PaCO2) were not correlated with age. At the exercise intensity of ventilatory anaerobic threshold, the PaCO2 increased, and the VA/VCO2 decreased, significantly with age, whereas the Vd/Vt was not related to age. Linear regression analysis demonstrated that the slope of the relationship between VE and VCO2 (deltaVE/deltaVCO2) and the slope of the relationship between VA and VCO2 (deltaVA/deltaVCO2) decreased with age. There were no gender differences in the regression slopes and the intercepts of the relationships. Results show that younger children breathe more during exercise to eliminate a given amount of CO2 to keep PaCO2 set point slightly but significantly lower than older children. This age dependence must be considered in investigating ventilatory control during exercise in children.

Adolescent↗
PubMed1998

Contributing factors in non-union of the humeral shaft fracture and the results of treatments.

Out of 218 fractures of humeral shaft treated in the department, 23 (10.5%) of them developed non-union. 14/23 (60.9%) fracture were located in middle third. Transverse (52.2%), short oblique (17.4%) and comminuted fracture (13.0%) constituted about 82% of all initial fracture pattern. Twelve cases (52.5%) were initially treated with hanging cast. Radial nerve palsy occurred in 4/23 (17.4%) of patient and all of them located at lower third of humerus and only one recovered after eight weeks of injury. Factors such as middle third comminuted opened fractures, soft tissue interposition, improper immobilization and poor patient compliance were found to be directly associated with the non-union. All non-unions healed following plating and bone grafting. Overall 17/23 patient (74%) had good results, 4/23 (17%) fair and 2/23 (9%) with poor functional results.

Adult↗