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Biomedical subjects

T Shimada

Publications and source records attributed to T Shimada.

At least 973 records · Page 54Linked to original sources
PubMed1981

Use of saliva for monitoring unbound free cortisol levels in serum.

In order to verify the clinical usefulness of saliva in assessing the adrenocortical function, we measured saliva cortisol levels by a radioimmunoassay after extraction with dichloromethane, and compared the results with the levels of serum unbound cortisol determined by the method of equilibrium dialysis. Paired samples of saliva and serum were obtained from 10 healthy male volunteers. Morning levels of saliva cortisol and serum unbound cortisol were 0.99 +/- 0.42 and 1.56 +/- 0.54 microgram/100 ml, respectively, where serum total cortisol was 19.28 +/- 3.56 microgram/100 ml. A well-defined diurnal rhythm and a greater response to ACTH stimulation were observed in saliva cortisol than in serum total cortisol. Kinetic study of injected cortisol revealed almost identical values for the compartments of saliva cortisol and serum unbound cortisol. The correlation coefficient (r) between the levels of saliva cortisol and serum unbound cortisol was 0.893 (p less than 0.001, n = 150). From these results we concluded that the measurement of saliva cortisol can be used sufficiently to monitor unbound free concentrations in serum.

Adrenal Cortex↗
PubMed1981

Effect of diltiazem on pacing-inducing ischemia in conscious dogs with coronary stenosis: improvement of postpacing deterioration of ischemic myocardial function.

The effects of diltiazem on regional myocardial function were examined in conscious dogs subjected to rapid cardiac pacing during coronary arterial stenosis. Ultrasonic dimension gauges were implanted within the left ventricle for measurement of the control and ischemic segment lengths. During coronary stenosis, percent shortening in the ischemic segment decreased by 18 percent. Heart rate was then suddenly increased by rapid cardiac pacing and this resulted in a further reduction of ischemic segmental shortening. On cessation of pacing, there was early potentiation of rate of increase of left ventricular pressure (dP/dt) and of control segmental shortening with subsequent exponential decay in sequential beats. In the ischemic segment, percent shortening returned to the control level in the first postpacing beat, became severely depressed at 5 seconds after pacing and gradually returned to the control level over the subsequent 5 minutes. Twenty minutes after administration of diltiazem, cardiac pacing was repeated in the same manner and there was less marked potentiation of dP/dt of the first postpacing beat. There ws no significant change in the postpacing dimension and function of the control segment; however, in the ischemic segment, although shortening of the first beat after termination of the pacing was similar, the post stimulation deterioration of shortening was significantly improved, percent shortening being augmented from 7.4 to 10.6 percent at 5 seconds (p less than 0.05). These findings indicate that diltiazem exerts protective effects on the ischemic myocardium by promoting a rapid recovery from ischemia.

Animals↗
PubMed1981

Covalent binding of polychlorinated biphenyls to proteins by reconstituted monooxygenase system containing cytochrome P-450.

Incubation in the presence of NADPH and molecular oxygen of 14C-labeled polychlorinated biphenyls (PCBs) and two tetrachlorobiphenyl (TCB) isomers with a reconstituted system containing NADPH-cytochrome P-450 reductase and cytochrome P-450, both purified from liver microsomes of phenobarbital(PB)-pretreated rabbits, led to covalent binding of radioactive metabolites of PCBs and TCBs to the protein components of the system. A rabbit liver cytosol fraction added to the system provided more binding sites for the activated metabolites and thus increased the extent of binding markedly. The binding reaction depended absolutely on the reductase, cytochrome P-450 and NADPH, and required dilauroyl phosphatidylcholine and sodium cholate for maximal activity. A further stimulation of the binding was attained by including cytochrome b5 in the reconstituted system. Four forms of cytochrome P-450, purified from liver microsomes of PB- and 3-methylcholanthrene(MC)-treated rabbits and rats, were used to reconstitute the PCB- and TCB-metabolizing systems, and it was found that PB-inducible forms of the cytochrome from both animals were more active than those inducible by MC in catalyzing the PCB- and TCrome P-450, purified from liver microsomes of PB- and 3-methylcholanthrene(MC)-treated rabbits and rats, were used to reconstitute the PCB- and TCB-metabolizing systems, and it was found that PB-inducible forms of the cytochrome from both animals were more active than those inducible by MC in catalyzing the PCB- and TCrome P-450, purified from liver microsomes of PB- and 3-methylcholanthrene(MC)-treated rabbits and rats, were used to reconstitute the PCB- and TCB-metabolizing systems, and it was found that PB-inducible forms of the cytochrome from both animals were more active than those inducible by MC in catalyzing the PCB- and TCB-binding reaction. Sodium dodecyl sulfate(SDS)-polyacrylamide gel electrophoresis indicated that, in the system containing the reductase, cytochrome P-450 and cytochrome b5, PCB metabolites bound to the reductase and cytochrome P-450, but not to cytochrome b5. In the presence of the liver cytosol fraction, the binding took place to many cytosolic proteins in addition to the reductase and cytochrome P-450.

Animals↗
PubMed1981

The formation of azoxy-2-phenylethane during the biological oxidation of phenylethylamine by rabbit liver microsomes.

Incubation of phenylethylamine with rabbit liver microsomes, divalent manganese and a NADPH generating system leads to the formation of azoxy-2-phenylethane, among other metabolic products. Approximately 38 nmol of the azoxy compound is formed form 10 mumol of phenylethylamine during a 30 min incubation. Azoxy-2-phenylethane was identified by comparison of its chromatographic (thin-layer, high pressure liquid and gas chromatography) properties with those of an authentic standard and was confirmed by mass spectrometry. The metabolism of phenylethylamine to azoxy-2-phenylethane appears completely dependent on the presence of divalent manganese; no reaction was observed in the absence of this metal or in the presence of equivalent concentrations of cupric ions. Azoxy-2-phenylethane was mutagenic, with S-9 activation, in S. typhimurium strains TA 100 and TA 1535 but not in TA 98 or TA 1537. This report constitutes the first demonstration of the formation of an aliphatic azoxy compound from the corresponding amine by a mammalian system.

Animals↗
PubMed1981

A Kr-81m inhalation method for detection of absence of uniform ventilation in asthma.

In an attempt to compare inhalation methods in detecting abnormal patterns of ventilation, the following four techniques were applied in 12 asthmatic patients: spontaneous respiration with a Kr-81m gas-air mixture (SP technique); serial inhalation of a Kr-81m gas-air mixture from the level of residual volume to total lung capacity (VC technique); bolus inhalation of 10 ml or Kr-81m gas from the level of residual volume, followed by air, to total lung capacity (RV technique); bolus inhalation of 10 ml of Kr-81m gas from the level of functional residual capacity, followed by air, to total lung capacity (FRC technique). Before exercise, abnormalities were detected by the RV and FRC techniques, but no abnormalities were detected by SP and VC techniques. On studies done after exercise, the abnormalities were detected by all the described techniques. However, they were best demonstrated by the RV technique and shown least well by the VC method.

Adolescent↗
PubMed1981

Removal of extracellular materials by HCL-tween treatment.

Glutaraldehyde-fixed tissues were treated with HCl and tween 20 to remove such extracellular materials as collagen fibers and basal laminae. In the HCl-treatment the collagen fibers were digested, while in the tween-treatment the basal laminae were removed. By this method the basal interdigitations of cells of the proximal tubule and the pericytes on th capillary wall were clearly demonstrable by scanning electron microscopy (SEM).

Animals↗
PubMed1981

[Echocardiographic features of false tendons: with special reference to phonocardiographic significance (author's transl)].

Echocardiographic features consistent with the findings of false tendons (FTs) were described in five out of 1,000 consecutive cases, and they were studied in order to determine whether FT was responsible for the systolic murmurs. Three had heart diseases including aortic regurgitation, 3 degrees AV-block with aortic regurgitation, and pericarditis and mitral stenosis, and the remainder cases had no heart disease. M-mode echocardiograms showed abnormal linear echoes in the outflow tract of the left ventricle in three cases, and in the left ventricle toward the apex in another two cases. Two-dimensional echocardiograms revealed long string-like echoes stretching from the upper parts of the interventricular septum across the ventricular cavity to the lateral wall of the left ventricle in three cases in the long and short axis views or four chamber view. In another two cases, there were long slender echoes binding the lower parts of the interventricular septum and the left ventricle in the apical view. These string-like echoes seemed to represent FTs reported previously in autopsy cases. Phonocardiography with pharmacological study (amyl nitrite and methoxamine) showed no significant systolic murmur, for which Fts had been considered to be responsible, even in a dilated left ventricle. We conclude that (1) M-mode and two-dimensional echocardiograms can demonstrate the presence of FTs, (2) two-dimensional echocardiograms might be utilized in differentiating FTs from other abnormal linear echoes in the outflow tract of the left ventricle seen in M-mode echograms, and (3) FTs do not necessarily cause systolic murmur.

Adult↗
PubMed1981

[Effects of verapamil on systolic time intervals and relaxation time in hypertrophic cardiomyopathy (author's transl)].

In order to determine the effect of verapamil, a calcium-channel blocking agent, on systolic performance and relaxation in hypertrophic cardiomyopathy (HCM), 12 patients with HCM and 10 normal subjects were studied. Echocardiograms, phonocardiograms, carotid pulses, and apex cardiograms were recorded simultaneously at the control state and 5, 10, and 15 min after intravenous injection of 10 mg of verapamil. After verapamil administration, heart rate was unchanged, while systolic blood pressure was slightly reduced in both groups. In normal subjects no significant changes were observed in systolic time intervals, such as ET, delta ET, PEP, delta PEP and PEP/ET, and mean VCF, except slightly prolonged delta ET after 5 min of the injection. The duration of isovolumic relaxation, (IIa-D) interval, taken as the period from the aortic valve closure (IIa) to the onset of mitral valve cusp separation and the time from IIa to the O point of the apex cardiogram, (IIa-O) interval, were 58 +/- 5 and 123 +/- 16 msec, respectively. The maximum velocity of the left ventricular posterior wall in early diastole (PWDV) was 128 +/- 10 mm/sec. These intervals and the velocity were not significantly changed after verapamil administration. In patients with HCM, ET and delta ET were unchanged, but PEP and delta PEP prolonged at 10 and 15 min after verapamil administration. PEP/ET was increased and mean VCF was reduced at 15 min after injection. In comparison with normal subjects, IIa-D interval and Ha-O interval were prolonged definitely at control, 92 +/- 21 and 190 +/- 28 msec, respectively. PWDV was slower than normal, 86 +/- 18 mm/sec at control. After verapamil, these intervals were shortened and PWDV fastened significantly. These results indicated that verapamil is regarded to have slight intrinsic negative inotropic action, suggesting the beneficial effect to reduce intraventricular pressure gradient, and also improve impaired myocardial relaxation in HCM.

Adult↗