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Biomedical subjects

H Masaki

Publications and source records attributed to H Masaki.

At least 253 records · Page 14Linked to original sources
PubMed1989

[Surgical treatment of coarctation of the aorta and interrupted aortic arch].

From December, 1984, through April, 1987, ten infants with coarctation of the aorta and six with interrupted aortic arch underwent staged repair of aorta and other cardiac lesions. Simultaneous pulmonary artery banding was performed in six of 8 patients with ventricular septal defect (VSD) and in all of seven patients with complex cardiac lesions. With first operation, there were no operative deaths and two late deaths. Eight of 14 survivors underwent total correction of associated lesions at three to 17 months after initial operation. VSD was closed in five patients with one operative death. One patient required pulmonary artery debanding alone because of decrease of VSD size. The Damus-Kaye-Stansel operation was performed successfully in one patient with Taussig-Bing anomaly and the Jatene operation was done in one with transposition of the great arteries. Based on these results, we prefer staged repair with pulmonary artery banding for coarctation or interruption of the aorta associated with complex cardiac lesions.

Aorta, Thoracic↗
PubMed1989

[Two cases of miliary tuberculosis following prosthetic valve replacement].

Pyrexia which occurs at late stage after prosthetic heart valve replacement must be suspected to be caused by prosthetic valve endocarditis (PVE). However, since confirmatory diagnosis is difficult, we are concerned about the treatment for so many cases. We encountered two cases who were suspected PVE at late stage after prosthetic aortic valve replacement and diagnosed miliary tuberculosis at autopsy. Here, we present a report of the two cases.

Aged↗
PubMed1989

[Early and late results of St. Jude Medical prosthesis in aortic and mitral portion].

January, 1980 to December, 1988, 118 patients underwent aortic (AVR) (45), mitral (MVR) (55), aortic and mitral (DVR) (21) valve replacement with a tilting disc valve prosthesis, the St. Jude Medical. Age ranged from 11 to 69 years (mean 49). There were seven death within thirty days after the surgery (AVR 1, MVR 5, DVR 1). Follow-up is complete and ranges from 1 month to 107 months (total 392, 4 patient-year (pt-yr), AVR 127.7 pt-yr, MVR 182.6 pt-yr, DVR 82.0 pt-yr). In the AVR group, three late deaths have occurred and actuarial survival at 8 years is 89 +/- 5%. Five patients have sustained thromboembolic episodes from linearized rate of 4.7%/patients-year, and the probability of remaining free of thromboembolism at 8 years is 83 +/- 7% in survivors longer than thirty days after the surgery. In the MVR group, one late death has occurred and actuarial survival at 8 years is 87 +/- 5%. Two patients have sustained thromboembolic episodes from linearized rate of 1.1%/patient-years, and the probability of remaining free of thromboembolism at 8 years is 86 +/- 1% in survivors longer than thirty days after the surgery. In the DVR group, four late deaths have occurred and actuarial survival at 8 years is 75 +/- 12%. Two patients have sustained thromboembolic episodes from linearized rate of 2.4%/patients-year, and the probability of remaining free of thromboembolism at 8 years is 85 +/- 5% in survivors longer than thirty days after the surgery. There is no significance of actuarial survival rate among three groups, but the rate of thromboembolism in AVR group is significantly higher than in other MVR and DVR groups in the first 20 months. Reoperation was carried out in one patient because of perivalvular leak. There have been no thromboses of the SJM valve and no mechanical valve failure. Because of this experience, The St. Jude Medical heart valve prosthesis is our prosthesis of choice for any patient undergoing valve replacement with a mechanical prosthesis.

Adolescent↗
PubMed1988

Coronary flow characteristics of left coronary artery in aortic regurgitation before and after aortic valve replacement.

In 6 patients with pure aortic regurgitation, the velocity waveform in the left anterior descending coronary artery (LAD) was measured using an 80-channel 20-MHz-pulse Doppler velocimeter before and immediately after aortic valve replacement. All patients showed normal coronary angiograms. Flow velocity was analyzed by both zero-cross and fast Fourier transform methods in real time. The LAD flow in severe aortic regurgitation was characterized by an increase in the systolic flow component, a small and rapidly decreased diastolic flow, an irregular velocity profile across the vessel, and a wider velocity spectrum. After aortic valve replacement, systolic flow decreased by 36.3 +/- 21.7% (p less than 0.01), whereas diastolic flow increased by 81.4 +/- 51.8% (p less than 0.05). The ratio of diastolic flow to total LAD flow increased from 63 +/- 13% to 82 +/- 7% (p less than 0.05). The velocity profile became more parabolic and had a narrow spectrum. These results suggest that operation for aortic regurgitation induces beneficial effects on the myocardial inflow immediately after valve replacement.

Adult↗
PubMed1988

Colicin E8, a DNase which indicates an evolutionary relationship between colicins E2 and E3.

Colicin E8-J and its immunity protein were characterized with regard to their activities and gene structures. Colicin E8 is a complex of proteins A and B; protein A (the naked E8) exhibits an apparently nonspecific DNase activity that is inhibited by protein B (the immunity protein), as in the case of colicin E2. The nucleotide sequence of the downstream half of the colicin operon of ColE8-J was determined to be highly homologous to that of ColE2-P9, with the exception of the hot spot region of the 3'-terminal segment of the colicin gene and the adjacent immunity gene. The immE2-like gene of ColE3-CA38 was, as assumed previously, extensively homologous to the immE8 gene of ColE8-J, and thus, ColE8-J was shown to be situated between ColE2-P9 and ColE3-CA38 in the evolution of the E-group Col plasmids.

Amino Acid Sequence↗
PubMed1988

[Studies on tissue PO2 and biochemical analysis of the skeletal muscle of legs with chronic arterial occlusive diseases].

Measurements of maximum tissue PO2 during 100% O2 inhalation (PtO2max) and biochemical analysis of the skeletal muscle were performed in 3 legs without ischemia and 14 legs with chronic arterial occlusive disease requiring amputation. There were significant good correlations between PtO2max and levels of pH, lactate, enzymes (CPK, LDH, Aldolase) and ATP in the skeletal muscle with ischemia. In regions in which PtO2max was below 10mmHg, ischemic changes in the muscle were considered to be irreversible. On the contrary, primary wound healing was obtained in regions with 40mmHg or more of PtO2max. Measurements of the PtO2max of the ischemic muscles provided much useful information concerning the reversibility of muscle ischemia and for decision of the amputation level.

Adenosine Triphosphate↗
PubMed1987

Unusual genetic codes and a novel gene structure for tRNA(AGYSer) in starfish mitochondrial DNA.

The nucleotide sequence of a 3849-bp fragment of starfish mitochondrial genome was determined. The genes for NADH dehydrogenase subunits 3, 4, 5, and COIII, and three kinds of (tRNA(UCNSer), tRNA(His), and tRNA(AGYSer) were identified by comparing with the genes of other animal mitochondria so far elucidated. The gene arrangement of starfish mitochondrial genome was different from those of vertebrate and insect mitochondrial genomes. Comparison of the protein-encoding nucleotide sequences of starfish mitochondria with those of other animal mitochondria suggested a unique genetic code in starfish mitochondrial genome; both AGA and AGG (arginine in the universal code) code for serine, AUA (isoleucine in the universal code but methionine in most mitochondrial systems) for isoleucine, and AAA (lysine) for asparagine. It was also inferred that these AGA and AGG codons are decoded by serine tRNA(AGYSer) originally corresponding to AGC and AGU codons. This situation is similar to the case of Drosophila mitochondrial genome. Variations in the use of AGA and AGG codons were discussed on the basis of the evolution of animals and decoding capacity of various tRNA(AGYSer) species possessing different sizes of the dihydrouridine (D) arm.

Animals↗
PubMed1986

Effects of excess dietary tyrosine or certain xenobiotics on the cholesterogenesis in rats.

Comparison of the effects of excess dietary tyrosine, DDT, chlorobutanol (Chloretone) or butylated hydroxyanisole (BHA) on serum cholesterol, hepatic activities of the rate-limiting enzyme of cholesterol synthesis,3-hydroxy-3-methylglutaryl coenzyme A reductase (EC 1.1.1.34) and in vivo rates of the hepatic cholesterol synthesis measured by 3H2O incorporation were investigated in rats. Serum cholesterol concentration was significantly higher in rats fed the DDT, chlorobutanol, BHA or excess tyrosine diets than in rats fed the control diet for 7 days. Serum cholesterol concentration remained higher compared to control rats when excess tyrosine was fed for 21 d. When rats were fed a basal diet after feeding a tyrosine excess diet for 2 wk, liver weight and serum cholesterol level returned to normal within 7 d. The incorporation of 3H2O into liver cholesterol and the activity of liver 3-hydroxy-3-methylglutaryl coenzyme A reductase were greater in rats fed excess tyrosine or certain xenobiotics than in control rats. Present results suggested that the increase in serum cholesterol concentration due to excess dietary tyrosine or certain xenobiotics is mainly attributable to the stimulation of liver cholesterol synthesis.

Administration, Oral↗