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Biomedical subjects

M Okazaki

Publications and source records attributed to M Okazaki.

At least 631 records · Page 35Linked to original sources
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Damped oscillation analysis of natural and artificial periodontal membranes.

The mechanical mobility of human teeth was studied by using a wave data treatment system with an accelerometer attached to a personal computer. The healthy teeth in different generations of men and women, who ranged in age from their teens to their forties, showed similar damped oscillation patterns. The spring constant and coefficient of viscous damping were estimated by using a viscoelastic model of damped oscillation with 1 degree of freedom. The coefficient of viscous damping increased dramatically with increases in the damping factor, whereas the spring constant scarcely varied. Silicone membranes were used as model periodontal membranes. The coefficient of viscous damping decreased with increases in silicone membrane thickness. Collagen membranes, which are expected to function as artificial periodontal membranes, were adhered to the model tooth by drying collagen gel and fixed with apatite-collagen composites. The collagen membranes showed damped oscillation wave patterns similar to those of human periodontal membranes.

Adult↗
PubMedDate not supplied

Differences in solubility of two types of heterogeneous fluoridated hydroxyapatites.

Two types of heterogeneous fluoridated apatites, H-F and F-H, were synthesized by supplying fluoride over the whole range of the degree of fluoridation (X = 0-1.0) during the initial or final half of the experimental period. Although X-ray diffraction patterns and scanning electron microscopy (SEM) photographs of both H-F and F-H type apatites were not significantly different, high-resolution transmission electron microscopy (HR-TEM) showed quite different features; H-F type apatites were elongated hexagons with electron beam damage in the core, while F-H type apatites were rather wider hexagons and approached the typical hexagon of fluorapatite. These results supported the previous speculations on the two different types of heterogeneous fluoridated hydroxyapatites synthesized with fluoride concentration stoichiometrically equivalent to that of fluorapatite: hydroxyapatite covered with fluorapatite and fluorapatite covered with hydroxyapatite. The apparent solubility of H-F type apatites decreased with increases in degree of fluoridation, while that of F-H type apatites decreased markedly and then remained almost constant.

Apatites↗
PubMedDate not supplied

Inhibiting action of carbohydrates on the growth of fluorapatite crystals.

Hydroxyapatite (HAp) and fluorapatite (FAp) were synthesized in the presence of carbohydrates (glucose, fructose, galactose and sucrose). X-ray diffraction analysis showed that the crystallinity of two FAp groups that were synthesized in the presence of glucose or sucrose decreased with the increase in carbohydrate content. In SEM photographs we found that the size of their crystals was small and the shape changed. However, FAp groups that were snythesized in the presence of fructose or galactose showed little change in their crystallinity and shape. Four carbohydrates had some influence on size, but not on shape or crystallinity when synthesizing HAp. These results suggest that glucose and/or sucrose has a chemical affinity to FAp and inhibits the growth of FAp crystals.

Analysis of Variance↗
PubMedDate not supplied

Clinical significance of natriuretic peptides and cyclic GMP in hemodialysis patients with coronary artery disease.

BACKGROUND: Plasma concentrations of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and cyclic guanosine monophosphate (cGMP) are suitable markers of 'dry body weight' (DW) in hemodialysis (HD) patients. However, it is still unknown whether these markers can be applied to patients with renal failure and coronary artery disease (CAD). We examined the reliability of these peptides as volume markers in HD patients with CAD. We also assessed the relationship between natriuretic peptides and indices of left ventricular (LV) function. METHODS: Plasma concentrations of ANP, BNP and cGMP were determined before and after HD in patients with CAD (group 1, n = 19, mean age 63 +/- 12 years) and were compared with those of patients without cardiac disease (group 2, n = 20, age 61 +/- 15 years). Using data obtained by cardiac catheterization, we examined the relationship between natriuretic peptides and indices of LV function in HD patients with CAD. RESULTS: Baseline ANP (244 +/- 205 pg/ml), BNP (713 +/- 928 pg/ml) and cGMP (29.6 +/- 21.6 pmol/ml) were significantly higher in group 1 than in 11 healthy volunteers (18.6 +/- 9.9 pg/ml, 7.7 +/- 7.6 pg/ml, cGMP 8.9 +/- 4.9 pmol/ml, respectively). HD significantly reduced plasma ANP (87 +/- 75 pg/ml) and BNP (477 +/- 702 pg/ml) although they were still above normal control. HD reduced plasma cGMP (7.2 +/- 4.5 pmol/ml) to normal values, suggesting the elimination of cGMP across the dialyzers. Baseline levels of ANP, BNP and cGMP in group 2 were less than those of group 1 but higher than the control. HD reduced natriuretic peptides in group 2 to levels lower than those in post-HD group 1. After HD, there was no significant correlation between reductions in body weight and changes in ANP or BNP. Baseline ANP and BNP levels closely correlated with pulmonary artery pressure, pulmonary artery wedge pressure, left ventricular end-diastolic pressure and left ventricular ejection fraction. A significant correlation was observed between BNP levels and the severity of CAD. CONCLUSION: ANP, BNP and cGMP seem to be a useful markers for fluid overload but not for DW in HD patients with CAD. Plasma ANP and BNP might be useful markers for left ventricular function.

Atrial Natriuretic Factor↗
PubMedDate not supplied

Immunohistochemical detection of estrogen receptor in invasive human breast cancer: correlation with heat shock proteins, pS2 and oncogene products.

The authors immunohistochemically studied the expression of the estrogen receptor (ER), 27-kD heat shock protein (HSP27) and pS2 in 118 invasive primary human breast cancers. Positive nuclear staining of the ER was detected in 64% of the cases and was closely correlated with the biochemical assay (p < 0.0001). ER-positive tumors were significantly decreased with tumor size and stage (p < 0.001 each), but not with lymph node status. Positivity of the ER was correlated with the cytoplasmic expression of HSP27 (p < 0.005), pS2 (not significant) and HSP70 (not significant). ER negativity was significantly correlated with the expression of p53, epidermal growth factor receptor (EGFR) and c-erbB-2 (p < 0.05 each). Thus, it was concluded that ER-positive breast carcinomas, relatively small in size, preferentially expressed HSP27, HSP70 and pS2 and that ER-negative tumors, relatively large in size, were predisposed to express p53, EGFR and c-erbB-2.

Breast Neoplasms↗