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Biomedical subjects

Y Doi

Publications and source records attributed to Y Doi.

At least 397 records · Page 22Linked to original sources
PubMed1989

[Correlation of various types of perfusion defects with supraventricular and ventricular arrhythmias in hypertrophic cardiomyopathy].

To ascertain the relationship between the types of myocardial perfusion defects and supraventricular and ventricular tachyarrhythmias in hypertrophic cardiomyopathy (HCM), 26 patients were studied with dipyridamole-loading thallium-201 scintigraphy and the results were correlated with 24-hour ambulatory ECG, echocardiograms and hemodynamic data. Myocardial perfusion defects were detected in 10 of the 26 patients (38%); three with large defects (LD) and seven with multiple small defects (SD). The patients with defects had greater degree of asymmetric septal hypertrophy (1.82 +/- 0.49 vs 1.27 +/- 0.38, p less than 0.01) and lower cardiac indices (2.35 +/- 0.31 vs 2.70 +/- 0.43, p less than 0.05) than did the patients without defects. Paroxysmal atrial fibrillation (PAf) and/or paroxysmal supraventricular tachycardia (PSVT) were observed in six of the 10 patients with defects (60%) and in four of the 16 patients without defects (25%). Ventricular tachycardia (VT) was identified in six of the 10 patients with defects (60%) but in only three of the 16 patients without defects (19%) (p less than 0.05). Among 10 patients with defects, PAf and/or PSVT were present in six of the seven patients with SD, but not in any of the patients with LD (p less than 0.05). VT was present in five of the seven patients with SD and in one of the three patients with LD. In conclusion, 1) perfusion defects in HCM are associated with greater degree of asymmetric septal hypertrophy, the lower cardiac indices, and higher prevalences of PAf, PSVT and VT; 2) Perfusion defects can be classified in two types; ie., multiple small defects and large defects; 3) Patients with multiple small defects commonly have PAf, PSVT as well as VT. This correlation may be of clinical importance, particularly in evaluating the causes of the defects and mechanisms of these arrhythmias.

Adolescent↗
PubMed1989

[Self-setting apatite cement. 8. Dissolution and remineralization behavior of 45Ca-apatite cement].

Self-setting apatite cement hardens into a mass of single phase apatite when mixed with diluted phosphoric acid. Structurally this mass consists of two types of apatite, i.e. the seed apatite used as a setting accelerator and the matrix apatite formed afterward in the reaction of dicalcium phosphate dihydrate (DCPD) and tetracalcium phosphate (Te-CP). To investigate the dissolution behavior of self-setting apatite cement in detail, two types of 45Ca labeled apatite cement were prepared. In one, the seed apatite was labeled with 45Ca (45Ca-HAp cement) and in the other the matrix apatite was labeled with 45Ca through use of 45Ca-DCPD (45Ca-DCPD cement). Solubility, estimated from the concentration of 45Ca released in 1 mM of organic acid (e.q. acetic, lactic, or citric acid) with initial pH adjusted to 4.0 at 37 degrees C, was approximately zero for 45Ca-HAp cement, whereas the solubility of 45Ca-DCPD cement was approximately the same as unlabeled cements used so far. This finding suggests that dissolution of the matrix apatite governs dissolution of the set cement, though comparison of X-ray diffraction patterns and electron micrographs of the seed apatite and apatite in the set cement showed no essential difference in crystallinity and crystal shape. The fact that the matrix apatite was formed by enveloping the seed apatite may account for the preferential dissolution of matrix apatite. In synthetic saliva labeled with 45Ca having a degree of supersaturation with respect to apatite comparable to rest saliva, 45Ca concentration in solution decreased once the cement pellet was introduced.(ABSTRACT TRUNCATED AT 250 WORDS)

Apatites↗
PubMed1989

[Self-setting apatite cement. VII. Barium-apatite as radio-opaque medium].

Addition of barium hydroxyapatite (BaAp) successfully bestowed clinically acceptable radioopacity to the self-setting apatite cement consisting of an equimolar mixture of tetracalcium phosphate and dicalcium phosphate dihydrate. To accelerate the setting reaction which was retarded by Ba2+ released from BaAp at a lower pH during first stage of spatulation with 20 mM phosphoric acid, calcium hydroxyapatite (CaAp) was added to the cement mixture. At about 20 wt% of BaAp and 20 wt% CaAp, the setting reaction proceeded at a neutral or weak alkaline pH, which is one of the most promising aspects of the self-setting cement and assures that this type of cement may be the least irritating of the dental cements presently available. The cement spatulated at L/P = 0.4 set within 10 minutes and its radiopacity was comparable to or more than that of tooth enamel. The wet compressive strength of the set cement stored for one day in synthetic saliva at 37 degrees C was approximately 100 kgf/cm2. Although this value is almost one fourth that of 40 wt% CaAp cement, this cement appears to be strong enough to apply as root canal filling material.

Barium↗
PubMed1989

[Detection and classification of coronary artery disease by dipyridamole perfusion scintigraphy: its prognostic significance].

To detect coronary artery disease (CAD) noninvasively and to predict the occurrence of future cardiac events, 671 patients were evaluated using dipyridamole perfusion scintigraphy. 1. Although chest pain and ST depression were induced by the administration of dipyridamole in 34% and 22% of the patients, respectively, and additional intravenous aminophylline was needed in 19% of the patients, dipyridamole perfusion scintigraphy could be completed in nearly all patients. In contrast, treadmill exercise test was not accomplished in 24% of the patients. 2. The patients were classified in three groups by scintigraphic perfusion defects; i.e., group I (322 patients) with fixed defects, group II (107 patients) with reversible defects, and group III (242 patients) without perfusion defects. The patients in Group I were subclassified three groups according to three high risk parameters (extensive fixed defect, partial redistribution and diffuse slow washout)--group Ia (69 patients) with two or more high risk parameters, group Ib (144 patients) with one high risk parameter and group Ic (109 patients) without high risk parameters. 3. Coronary angiography performed in 377 patients revealed significant CAD (luminal narrowing greater than or equal to 50%) in 96%, 89%, 56%, 90% and 8% of the patients in groups Ia, Ib, Ic, II and III, respectively. Multi-vessel CAD was present in 87%, 32%, 11%, 51% and 2% of the patients in each group, respectively.

Adolescent↗
PubMed1989

[Clinical significance of prominent negative T waves induced by exercise test].

The significance of deep T wave inversion during and after exercise in patients with coronary artery disease has not been studied well. Using the treadmill exercise test (modified Bruce's protocol) and coronary arteriography, we evaluated 361 patients suspected of having coronary artery disease. Results were compared for patients who developed significant T wave inversions of greater than 8 mm (prominent negative T wave: PNT) and for patients who had significant down-sloping ST depressions (DS). Sixteen patients had PNT (4%) which became maximum three to five min after exercise, and ranged in depth from 8 to 15 mm (10.9 +/- 2.4 mm). There were 83 patients with DS (23%). Exercise duration was 3.3 +/- 1.4 min in the PNT group and 4.4 +/- 1.9 min in the DS group (p less than 0.01). Prevalence of three-vessel disease or left main trunk disease was 88% (14 patients) in the PNT group, 28% in the DS group, and 19% (70 patients) in the entire 361 patients. Among the 14 patients who had three-vessel disease or left main trunk disease in the PNT group, the degree of multiple stenoses exceeded 90% in the major coronary arteries and that of the left main trunk stenosis exceeded 75%. The two remaining patients included one with two-vessel disease and severe 99% narrowing of the major coronary arteries and one patient having one-vessel disease with vasospastic angina during exercise. Prevalence of coronary revascularization was 69% in the PNT group and 36% in the DS group (p less than 0.025).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[A case of lymphangioma of penis].

A 9-year-old boy was seen with chief complaint of a penile mass with pain. The movable mass was palpable in the subcutaneous tissue of the penis apart from the median raphe. The mass was excised enbloc. Histological examination revealed that the mass was a lymphangioma of penis consisting of several endothelial-lined cysts. Convalescense was uneventful. Eighteen cases of lymphangioma or lymphangiectasia of penis including the present case in the Japanese literature are reviewed.

Child↗
PubMed1989

[A renal trauma: evaluation by dynamic CT].

To document the severity and degree of renal injury multiple studies may be necessary, including excretory urography, nephrotomography, arteriography and ultrasonographic examination. Even these extensive studies fail at times to provide sufficient information for treatment of the injury. However, the parenchymal injuries and extrarenal hematomas are depicted more accurately by computed tomography (CT). Moreover, dynamic CT can assess parenchymal enhancement during the capillary phase. Therefore, dynamic CT is useful in assessing the renal contusion and hematoma. In addition, it appears to be highly reliable and relatively noninvasive means of diagnosing renal trauma.

Humans↗
PubMed1989

[Clinical significance of negative dipyridamole perfusion scintigram].

Six hundred seventy-one patients who had dipyridamole perfusion scintigraphy were classified into two groups; ie, 242 patients without perfusion defect (Group A) and 429 patients with perfusion defect (Group B). Clinical significance of negative scintigram was then assessed and correlated with coronary angiographic findings and prevalence of cardiac events. 1) Significant coronary artery disease (greater than 50% luminar narrowing) was present in 7 of 92 patients (8%) in Group A and in 235 of 285 patients (82%) in Group B. Multi-vessel coronary artery disease was found only in 2 patients (2%) in Group A and in 119 patients (42%) in Group B. 2) During a mean follow-up period of 29 months, 48 cardiac death (8%) and 19 nonfatal cardiac events (3%) occurred in 619 medically treated patients. These cardiac complications were observed in 7 of 242 patients (3%) in Group A and in 60 of 377 patients (16%) in Group B, including 4 (2%) and 44 (12%) cardiac deaths, respectively. In conclusion, it is rare to see severe organic coronary artery disease and future cardiac event in patients with negative dipyridamole perfusion scintigram. It may be, therefore, stated that it is unnecessary to perform coronary angiography in these patients, unless they have symptoms which cannot be controlled medically.

Adolescent↗
PubMed1988

Adrenal renin: a possible local hormonal regulator of aldosterone production.

The complete renin-angiotensin system is present in the adrenal cortex: prorenin, renin, angiotensinogen, angiotensin I and II, and converting enzyme. Most of the renin found is probably synthesized there since the renin concentration increases after nephrectomy, and the mRNA for renin is present. The renin-angiotensin system has the highest activity in the zona glomerulosa cells, the site of aldosterone formation. A low-sodium diet or a high-potassium diet, or nephrectomy markedly increases the adrenal renin concentration in the zona glomerulosa cells without any effect on the fasciculata-medullary cells. There is a close correlation between adrenal renin and aldosterone production. The adrenal renin angiotensin system may be a local regulator of aldosterone production.

Adrenal Glands↗
PubMed1988

Biphasic effects of alcohol drinking on methamphetamine metabolism in man.

In methamphetamine (MAP) addicts, long-term ethanol ingestion 3-4 times per week induced an increased rate of p-hydroxylation of MAP and amphetamine (AMP). Simultaneous ingestion of ethanol and MAP inhibited both p-hydroxylation of MAP and AMP and N-demethylation of MAP in inebriated addicts. The p-hydroxylation of MAP and AMP was also significantly inhibited in daily drinkers despite the almost total absence of urinary ethanol. This suggests that the intensity of MAP-induced behavioral and psychological effects in MAP addicts may, in part, depend upon their drinking habits.

Adult↗