Computer-assisted patient information system.
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Humans↗
Biomedical subjects
M Yamaki
Publications and source records attributed to M Yamaki.
Studies on radiopaque composites containing ZrO2-SiO2 fillers prepared by the sol-gel process.
Radiopacity can facilitate diagnostic observations adjacent to dental composites. To produce radiopaque SiO2-based fillers, ZrO2-SiO2 powders containing up to 45wt% ZrO2 were manufactured by the sol-gel process. The radiopacity of experimental composites containing Bis-GMA+TEGDMA+CQ+DMAEMA monomer mixture (25 wt%) and ZrO2-SiO2 fillers (75 wt%) was evaluated and compared to that of human enamel and two commercial composites with different radiopacity. It became evident that the radiopacity of the experimental composites increased linearly with zirconium content and could match that of the control materials, while the composite containing 15wt% ZrO2-85wt% SiO2 filler possessed radiopacity analogous to that of human enamel. It was demonstrated here that the radiopacity of the composites could be precisely controlled by adjusting the ZrO2 content in ZrO2-SiO2 fillers. These radiopacity-adjustable composites have the potential to be very useful filling materials by enabling dentists to accurately distinguish secondary caries adjacent to the composite restorations.
Analysis of Variance↗
ADH resistance of LLC-pk1 cells caused by overexpression of cAMP-phosphodiesterase type-IV.
The studies of animal models of nephrogenic diabetes insipidus (NDI) suggest that abnormally high activity of cAMP phosphodiesterase (cAMP-PDE), may cause unresponsiveness to the diuretic effect of AVP. We explored whether overexpression of one of the cAMP-PDE type isozymes, PDE-IV, in [8-Arg]-vasopressin (AVP) sensitive renal epithelial LLC-PK1 cells can prevent the hormone-elicited cAMP increase. LLC-PK1 cells were stably transfected with ratPDE3.1 cDNA (which encodes for rolipram-sensitive PDE-IV), inserted in plasmid pCMV5 and then were compared with sham-transfected LLC-PK1 cells and wild LLC-PK1 cells. In the stably transfected clone (LLC-PK1-S #16), the rolipram-sensitive PDE-IV activity was about five times higher than in controls, whereas activities of other types of PDEs were not different. The presence of cognate mRNA for PDE-IV was confirmed by Northern blot. Whereas in the control cells (wild LLC-PK1 cells and sham-transfected LLC-PK1 cells), the incubation with 10(-7) M AVP increased cAMP more than tenfold, the LLC-PK1-S#16 cells with overexpressed cAMP-PDE were resistant to cAMP-increasing effects of AVP and forskolin. However, in the same LLC-PK1-S#16 cells the cGMP increases in response to nitroprusside were not diminished. The AVP-dependent cAMP accumulation in LLC-PK1-S#16 cells with overexpressed PDE-IV was restored by addition of roliprams which decreased cAMP-PDE activity to the levels similar to those in wild LLC-PK1 cells and sham-transfected LLC-PK1-#A1 cells. In contrast, inhibitors of other PDE isozymes (PDE-I or PDE-III) had little or no effect. Our findings show that excessive activity of cAMP-PDE, in this case of isozyme PDE-IV, can cause resistance to AVP which is analogous to that observed in collecting ducts of mice with hereditary nephrogenic diabetes insipidus.
3',5'-Cyclic-AMP Phosphodiesterases↗
Effects of post-curing by heat on the mechanical properties of visible-light cured inlay composites.
The aim of this study was to evaluate the effects of post-curing by heat on the mechanical properties of visible-light (V-L) cured three inlay composites and three posterior filling composites. One group was only photo-cured according to the manufacturers' recommended methods, while the other group was heat-treated at 100 degrees C for 15 min following initial cure by V-L. Knoop hardness, diametral tensile strength and compressive strength were measured to evaluate the mechanical properties. Cure performance was checked out by the solvent immersion test. Upon secondary-curing by heat, it was confirmed that the mechanical properties of the composites were increased moderately and the cure performance of the composites was also improved.
Composite Resins↗
Radiopacity of 12 visible-light-cured dental composite resins.
The radiopacity of 12 VL-cured composite resins was determined with reference to an aluminum step-wedge. Two anterior composites were radiolucent while two anterior and one anterior/posterior composites exhibited the radiopacity equal to, or slightly greater than, that of human enamel. Three posterior and one inlay composites possessed the radiopacity equivalent to, or in tiny excess of, that of human enamel. Three posterior composites had the radiopacity, fairly exceeding that of human enamel. Chemical analyses of the filler particles were carried out with SEM/EDX. It became evident that radiopaque fillers contained at least one radiopaque oxide component such as BaO, ZrO2 and Yb2O3 with varying concentrations. In general, the radiopacity of the composite resin was linearly proportional to the amount of the radiopaque oxide in the filler. It was suggested that ZrO2 was radiopacifier equivalent to, or even stronger than, BaO.
Composite Resins↗
Dental high-speed cutting of four cast alloys.
The purpose of this study was to evaluate dental high-speed cutting behaviour of four cast alloys, namely Ag-Pd-Cu-Au alloy, Ag-Zn-In-Sn alloy, Ni-Cr alloy and Ti. Weight-load cutting tests were conducted on four cast alloys, using two rotary cutting instruments, namely a diamond point and a carbide bur, both driven by an air-turbine handpiece. While the constant transverse load of 80 g was applied on the workpiece for 5s, the handpiece speed was measured during cutting as well as the volume of workpiece removal which took place. The cutting tests were repeated 10 times. We found that the cutting volumes of soft Ag-Pd-Cu-Au alloy and Ag-Zn-In-Sn alloy were considerably larger than those of hard Ni-Cr alloy and Ti. It was also clarified that the cutting effectiveness of the carbide bur was generally superior to that of the diamond point. With continuing use, however, the cutting capability of the carbide bur tended to decline while that of the diamond point remained quasi-constant.
Dental Alloys↗
Role of ATP-sensitive K+ channel on ECG ST segment elevation during a bout of myocardial ischemia. A study on epicardial mapping in dogs.
BACKGROUND: ATP-sensitive K+ channels are activated when the myocardium becomes ischemic. However, the role of the ATP-sensitive K+ current in the emergence of ECG ST changes during ischemia remained unclarified. METHODS AND RESULTS: The left anterior descending coronary artery (LAD) was cannulated and perfused with arterial blood from the carotid artery through a bypass tube in 8 anesthetized, open-chest dogs. An array of 60 unipolar electrodes mounted on a sock was used to record epicardial electrograms of the whole heart. Pinacidil (10 micrograms.kg-1 x min-1), an ATP-sensitive K+ channel opener, was infused into the bypass tube for 2 minutes, and the electrograms were recorded before and after the infusion. The elevation of the ST segment and the increase of QRST area were observed spatially over the LAD-perfused region. At the electrode showing the largest ST segment elevation, the activation recovery interval, an index of action potential duration, was shortened from 202 +/- 9 to 111 +/- 18 milliseconds (P < .001). These electrographic changes were similar to those noted in 2-minute coronary occlusion (n = 8). The extent of ST segment elevation during coronary occlusion was attenuated after the intravenous pretreatment with glibenclamide (0.3 mg/kg), a blocker of the KATP channel (n = 5). CONCLUSIONS: The findings of this study suggest that the activation of ATP-sensitive K+ channels during a bout of acute myocardial ischemia plays an important role in the emergence of ECG ST elevation.
Action Potentials↗
Hardness and fracture toughness of commercial core composite resins.
One important mechanical property of core composite resins is fracture toughness, KIC, which expresses serviceability in the oral cavity, such as the resistance to marginal fracture. KIC values of eight commercial core composite resins were examined by the single-edge notched-beam (S.E.N.B.) method. Two composites containing about 80 wt% Si3N4 fillers exhibited both the highest KIC value of around 2.0 MN.m-3/2 and the highest hardness value. The other six composites containing 66 to 86 wt% SiO2-based fillers had KIC values of around 1.2 to 2.0 MN.m-3/2, and there was a tendency toward higher KIC values as hardness increased. It was speculated that the clinical acceptability of core composite resins could be broadened, if dental clinicians selected composites with higher KIC values.
Composite Resins↗
Isozymes of cyclic-3',5'-nucleotide phosphodiesterases in renal epithelial LLC-PK1 cells.
Metabolism of cAMP and cGMP by the major types (families) of cyclic-3',5'-nucleotide phosphodiesterases (PDE) was studied in confluent renal epithelial LLC-PK1 cells grown in vitro. LLC-PK1 cells mainly contain the cAMP-specific rolipram-sensitive PDE type-IV (PDE-IV), the Ca(2+)-calmodulin dependent PDE type-I and cGMP-specific PDE type-V; all these PDEs are mainly localized in cytosol. Analysis of PDE activities in soluble extract of LLC-PK1 cell homogenate by FPLC ionex chromatography on Mono-Q column also disclosed the presence of low activities of cGMP-stimulated PDE-II and PDE-III. Moreover, activity of PDE-IV was resolved into four distinct chromatographic peaks. The increase of cAMP level in response to incubation of intact LLC-PK1 cells with vasopressin (AVP) was markedly enhanced in the presence of rolipram, but not in the presence of other PDE isozyme-specific inhibitors. Incubation with AVP and atriopeptin (ANP) together resulted in increase in cGMP and a small decrease of cAMP accumulation in LLC-PK1 cells. Results of these studies first show that the LLC-PK1 cells contain all five major types of PDE isozymes where PDE-IV, PDE-I and PDE-V are quantitatively predominant. The rolipram-sensitive PDE-IV, present in several chromatographically distinct forms, appears to be the key PDE isozyme involved in control of cAMP generated in response to stimulation by AVP in LLC-PK1 cells.
3',5'-Cyclic-AMP Phosphodiesterases↗
Characterization of inorganic fillers in visible-light-cured dental composite resins.
Inorganic fillers in seven visible-light (VL)-cured dental composite resins were examined for their size, composition, phase and content, employing the following analytical instruments. SEM observations indicated that five samples could be classified into the hybrid type while the remaining two belonged to micro-filled and sub-micron types. EDX analyses revealed that five samples contained BaO while others lacked BaO. XRD analyses showed that three were in vitreous phase, two were in the crystalline phase and two were mixtures of both. DTG thermal analyses indicated that the hybrid type composites had the higher inorganic filler content (wt%) than the composites of two other types. In conclusion, wide varieties exist in the inorganic fillers in VL-cured dental composite resins currently utilized.
Aluminum Oxide↗
In-vitro and in-vivo wear profile of composite resins.
The aim of this study was to evaluate in-vitro wear by two types of slurry of 10 commercial composite resin materials (seven hybrid and three microfilled composites). There was great variation in the in-vitro wear pattern by two types of slurry. The wear rate of microfilled composites was greater than that of hybrid composites, and a negative correlation was observed between wear rate and Knoop hardness values among all materials when hydroxyapatite slurry was used. In contrast, the wear rate of hybrid composites was greater than that of microfilled composites when abraded by green carborundum slurry. These abraded surfaces were compared with SEM micrographs of in-vivo composites surface after 4 years of service. The profile of in-vivo wear surfaces was found to be similar to that of in-vitro wear surfaces abraded with hydroxyapatite slurry.
Composite Resins↗
Cyclic 3',5'-nucleotide diesterases in dynamics of cAMP and cGMP in rat collecting duct cells.
We studied cyclic 3',5'-nucleotide phosphodiesterase (PDE) isozymes and their role in adenosine 3',5'-cyclic monophosphate (cAMP) and cGMP metabolism in a rat inner medullary collecting duct (IMCD) cell line. The homogenized and fractionated IMCD cells of cAMP-PDE and all of cGMP-PDE activity were found in the cytosol. The majority of cytosolic cAMP-PDE (greater than 50%) was isozyme PDE-IV; the Ca(2+)-calmodulin-sensitive PDE-I was present only in cytosol. Preincubation of IMCD cells with PDE-IV inhibitor rolipram markedly (5x) enhanced levels of cAMP both basal and in the presence of [Arg8]vasopressin (AVP). Cilostamide (for PDE-III) or vinpocetine had no effect, whereas PDE-I inhibitor 8-methoxymethyl-3-isobutyl-1-methylxanthine (8-MeoM-IBMX) enhanced AVP-dependent cAMP levels. Exposure of IMCD cells to 2 microM ionomycin decreased both basal and AVP-stimulated cAMP. Depletion of Ca2+ by preincubation of IMCD cells in the Ca(2+)-free medium with ethylene glycol-bis (beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid markedly enhanced the stimulatory response of cAMP to AVP, and addition of 8-MeoM-IBMX further enhanced the AVP response. The levels of cGMP, basal or in response to atriopeptin (ANP), were not affected by PDE-V inhibitor zaprinast, but both inhibitors of PDE-I, 8-MeoM-IBMX and vinpocetine, increased basal cGMP, and 8-MeoM-IBMX also increased cGMP levels enhanced by ANP. The depletion of Ca2+ from IMCD cells alone had no effect on cGMP levels, but effects of 8-MeoM-IBMX and vinpocetine on the ANP-stimulated cGMP levels were enhanced.(ABSTRACT TRUNCATED AT 250 WORDS)
2',3'-Cyclic-Nucleotide Phosphodiesterases↗
Localization of mRNAs coding for isozymes of plasma membrane Ca(2+)-ATPase pump in rat kidney.
We have studied localization of mRNAs coding isozymes of rat plasma membrane Ca(2+)-adenosinetriphosphatase pump (rPMCA) in the rat kidney, with use of reverse transcription (RT) with subsequent amplification by polymerase chain reaction (PCR). When zones of the kidney were separated by macrodissection, a large amount of mRNA coding isozyme rPMCA1 was found in all zones; mRNA for isozyme rPMCA2 was abundant in cortex and in outer medulla, and mRNA for isozyme rPMCA3 was prominent in outer medulla. The mRNAs were analyzed in microdissected cortical nephron segments by use of RT-PCR approach described previously [T. Moriyama, H. R. Murphy, B. M. Martin, and A. Garcia-Perez. Am. J. Physiol. 258 (Renal Fluid Electrolyte Physiol. 27): F1470-F1474, 1990]. We detected mRNA for isozyme rPMCA2 in microdissected distal convoluted tubules (DCT) and in cortical thick ascending limbs (CTAL) and, less consistently, also in proximal convoluted tubule and in glomeruli. The mRNA for isozyme rPMCA1 was abundant in glomeruli but was absent in all examined cortical tubular segments. Our results document that mRNAs for all three major isozymes of rPMCA are present and show a unique distribution in the three major zones of rat renal parenchyma. Specific mRNA coding for rPMCA2 was detected in cortical tubules, namely in CTAL and DCT, whereas mRNA coding isozyme rPMCA1 was found in glomeruli. We suggest that isozyme rPMCA2 might be specifically related to epithelial cells and their function, whereas rPMCA1 is probably a component of nonepithelial cells including these in glomeruli.
Animals↗
Relation between recovery sequence estimated from body surface potentials and T wave shape in patients with negative T waves and normal subjects.
BACKGROUND: Advances in analytical methods of the epicardial electrical potentials allowed us to demonstrate spatial distributions of local recovery. Because local recovery will be reflected in events on body surface ECG mapping, abnormalities in recovery sequence that may be responsible for the origin of negative T waves can be detected from body surface potentials. METHODS AND RESULTS: Eighty-seven unipolar ECGs were recorded simultaneously from the entire thorax in patients having negative T waves on left anterior precordial leads and in normal subjects. These included 40 patients with anterior myocardial infarction (MI), 21 patients with left ventricular hypertrophy (LVH), and 44 male volunteers. We measured Tmax time, defined as the instant of maximal first derivative of the T wave as the index of local recovery (Wyatt's method). Parameters related to T wave potentials were positive T wave amplitude, negative T wave amplitude, and T integral. Significant correlations were observed between the Tmax time and each of the T wave potentials. The T wave potentials were dependent on Tmax times. In the anterior MI, the late Tmax times were located on the upper left anterior chest and early Tmax times on the lower right lateral chest. In the LVH, the area showing a delayed recovery was displaced in a left downward direction compared with anterior MI. CONCLUSIONS: Body surface Tmax time distributions clearly separate two negative T wave groups, i.e., anterior MI and LVH. Appearance of the negative T waves correlates well with the presence of the area with delayed Tmax time on the spatial distribution.
Adult↗
Spectral analysis of 87-lead body surface signal-averaged ECGs in patients with previous anterior myocardial infarction as a marker of ventricular tachycardia.
BACKGROUND: There were few studies on the relation between the body surface distribution of high- and low-frequency components within the QRS complex and ventricular tachycardia (VT). METHODS AND RESULTS: Eighty-seven signal-averaged ECGs were obtained from 30 normal subjects (N group) and 30 patients with previous anterior myocardial infarction (MI) with VT (MI-VT[+] group, n = 10) or without VT (MI-VT[-] group, n = 20). The onset and offset of the QRS complex were determined from 87-lead root mean square values computed from the averaged (but not filtered) ECG waveforms. Fast Fourier transform analysis was performed on signal-averaged ECG. The resulting Fourier coefficients were attenuated by use of the transfer function, and then inverse transform was done with five frequency ranges (0-25, 25-40, 40-80, 80-150, and 150-250 Hz). From the QRS onset to the QRS offset, the time integration of the absolute value of reconstructed waveforms was calculated for each of the five frequency ranges. The body surface distributions of these areas were expressed as QRS area maps. The maximal values of QRS area maps were compared among the three groups. In the frequency ranges of 0-25 and 150-250 Hz, there were no significant differences in the maximal values among these three groups. Both MI groups had significantly smaller maximal values of QRS area maps in the frequency ranges of 25-40 and 40-80 Hz compared with the N group. The MI-VT(+) group had significantly smaller maximal values in the frequency ranges of 40-80 and 80-150 Hz than the MI-VT(-) group. These three groups were clearly differentiated by the maximal values of the 40-80-Hz QRS area map. CONCLUSIONS: It was suggested that the maximal value of the 40-80-Hz QRS area map was a new marker for VT after anterior MI.
Electrocardiography↗
Dipyridamole electrocardiography test for the assessment of the severity of coronary artery disease.
The purpose of this study was to investigate the relationship of dipyridamole-induced ST changes to the severity of coronary artery disease. The subjects were 100 patients without myocardial infarction who underwent coronary arteriography for the diagnosis of coronary artery disease. The dipyridamole injection test (D) (0.568 mg/kg/4 min), and symptom-limited treadmill exercise test (T) were performed separately. Body surface electrocardiographic mapping of 87 leads was performed in both tests. The incidences of significant ST depression greater than or equal to 0.10 mV, number of leads showing significant ST depression (nST) and the maximal voltage of ST depression (maxST) in D and T were compared to the number of diseased coronary arteries. In patients without significant coronary stenosis (0VD group), the incidence of ST depression in the dipyridamole test was significantly lower than that in the treadmill test (D 9% vs T 47%, p less than 0.01). While, in one vessel disease (1VD), two vessel disease (2VD), and three vessel disease (3VD) groups, there was no significant difference in the incidence of ST depression between the dipyridamole test and the treadmill test (in 1VD, D 44% vs. T 65%; in 2VD, D 67% vs. T 93%; and in 3VD, D 93% vs. T 96%). In the dipyridamole test, nST was 0.6 +/- 2.4 in 0VD, 4.5 +/- 6.9 in 1VD, 4.1 +/- 4.5 in 2VD, and 10.6 +/- 8.1 in 3VD. Significant differences were found between 0VD and 1VD (P less than 0.05), 0VD and 3VD (P less than 0.01), 1VD and 3VD (P less than 0.01), and 2VD and 3VD (p less than 0.01). The maxST in the dipyridamole test was 0.02 +/- 0.04 mV in 0VD, 0.10 +/- 0.12 mV in 1VD, 0.13 +/- 0.11 mV in 2VD, and 0.22 +/- 0.11 mV in 3VD. Significant differences were found between 0VD and 1VD (p less than 0.01), 0VD and 2VD (p less than 0.01), 0VD and 3VD (p less than 0.01), 1VD and 3VD (p less than 0.01), and 2VD and 3VD (P less than 0.01). For the diagnosis of 3VD, the dipyridamole ECG test had as high a sensitivity (93% vs 96%), higher specificity (68% vs 38%, p less than 0.01), and higher predictive accuracy (75% vs 54%, p less than 0.01) than the treadmill test.(ABSTRACT TRUNCATED AT 400 WORDS)
Adult↗
Dipyridamole electrocardiography test for the detection of severe coronary artery stenoses.
To investigate the relationship between dipyridamole-induced ST depression and the severity of coronary artery stenosis, the dipyridamole injection test (D) at 0.568 mg/kg/4 min, and the symptom limited treadmill exercise test (T) were performed separately in 16 normal volunteers and 167 patients who underwent coronary arteriography [91 patients without myocardial infarction (non-MI group) and 76 patients with previous myocardial infarction (MI group)]. Standard 12-lead electrocardiogram and body surface mapping of 87 leads were recorded in both tests. None of the normal volunteers had significant ST depression (greater than or equal to 0.10 mV) in D or T. Regarding the non-MI group, D had as high an incidence of ST depression as T (83% vs 93%) in patients with maximal coronary stenosis greater than or equal to 90%, while in those with maximum coronary stenosis less than 90%, D had a lower incidence of ST depression than T (16% vs 48%, p less than 0.01). For the MI group, the incidence of ST depression was compared to the maximal coronary artery stenosis supplying the non-infarcted area. In patients with maximal coronary artery stenosis greater than or equal to 90%, D had as high an incidence of ST depression as T (71% vs 64%). While, D had a lower incidence of ST depression than T (19% vs 35%, p less than 0.05) in those with maximum coronary artery stenosis less than 90%. For the diagnosis of coronary artery stenosis of greater than or equal to 90%, D had as high sensitivity (non-MI group, 82% vs 93%; MI group, 71% vs 64%) and higher specificity (non-MI group, 84% vs 52%, p less than 0.01; MI group, 81% vs 65%, p less than 0.05) compared with T. This study demonstrated that dipyridamole ECG is a sensitive and specific test to detect severe coronary artery stenosis.
Adult↗
Presence of lower temperature-dependent antibody with low avidity to C100-3 (HCV) antigen in voluntary blood donors.
Serum samples with lower temperature-dependent antibody with low avidity to C100-3 (HCV) antigen were found in 0.19% of 23,197 voluntary blood donors at this blood center. They showed positive C100-3 antibody activity at 24 C but not at 37 C. The antibody activity bound to C100-3 antigen at lower temperature disappeared after incubation for 60 min at 37 C or treatment with 8 M urea. Other markers of hepatitis C virus infection, especially the presence of HCV-RNA were demonstrated in some of these serum samples and the importance of this phenomenon is discussed with regard to virus screening of blood donors for hepatitis C.
Antibody Affinity↗