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Biomedical subjects

Y Yang

Publications and source records attributed to Y Yang.

At least 1,423 records · Page 79Linked to original sources
PubMed1987

Phospholipid methylation in canine myocardium: kinetic characteristics and the effect of endotoxin administration.

The kinetic characteristics and the effect of endotoxin administration on the enzymatic methylation of phospholipids in dog heart microsomes were studied using S-adenosyl-L-[methyl-3H]methionine as a methyl donor. Kinetic studies in control dogs reveal that the stepwise methylation of phosphatidylethanolamine to phosphatidylcholine was catalyzed by three different enzymes. Methyltransferase I catalyzed the methylation of phosphatidylethanolamine to phosphatidyl-N-monomethylethanolamine, had a very low Km (approximately 1.5 microM) for S-adenosylmethionine, and a pH optimum of 6.5, and it was stimulated by Mg2+ and Ca2+. Methyltransferase II catalyzed the methylation of phosphatidyl-N-monomethylethanolamine to phosphatidyl-N,N-dimethylethanolamine, had a low Km (8-12 microM) for S-adenosylmethionine, and a pH optimum of 8.5, and it was stimulated by low concentrations (less than 1 mM) of Ca2+ but was unaffected by Mg2+. Methyltransferase III catalyzed the formation of phosphatidylcholine from phosphatidyl-N,N-dimethylethanolamine, had a high Km (approximately 33 microM) for S-adenosylmethionine, and a pH optimum of 9.5, and it was unaffected by Mg2+ or Ca2+. Experiments with trypsin digestion indicate that methyltransferases I and III were partially embedded while methyltransferase II was completely exposed to the surface of the membrane. Endotoxin administration (2 and 4 hr) decreased the Km and Vmax by 30 to 36% and 24 to 37.7%, respectively, for S-adenosylmethionine. Since the enzymatic methylation of phospholipids has been implicated to play an important role in the regulation of membrane structure and function, the endotoxin-induced decreases in the Km and Vmax of phospholipid-methylating enzymes in dog heart microsomes may contribute to the development of myocardial dysfunction in endotoxin shock.

Animals↗
PubMed1987

Argon laser angioplasty with a laser probe.

A preliminary basic study of argon laser angioplasty with the use of a specially designed probe is presented. Arterial specimens were harvested from 10 amputated lower extremities. The studies included the evaluation of coaxial laser angioplasty in 10 partially or totally occluded arteries; the observation of the effect of perpendicularly applied laser energy on 35 thrombi, 54 soft and 10 hard atherosclerotic, and 51 normal arterial walls; the comparison of laser energy requirements for coaxial vessel lumen enlargement or recanalization vs. perpendicular penetration in 10 occluded, hard atherosclerotic arteries; and the spectrographic analysis of calcium density gradient in two specimens. The results showed that the power required for vessel lumen enlargement was 10 +/- 6 J/mm of atherosclerotic vessel (mean +/- standard deviation). The probe followed the original arterial lumen, did not perforate the vessel wall, and created a smooth, enlarged path. The power required to penetrate perpendicularly to a similar depth for thrombi, soft and hard atherosclerotic plaques, and normal arterial walls was 15 +/- 4, 30 +/- 15, 65 +/- 32, and 246 +/- 123 J/mm, respectively. In the hard calcified specimens, laser energy required for coaxial lumen enlargement or recanalization was significantly less than that for perpendicular penetration (p less than 0.05), which correlated with the calcium density map indicating an increase from inside to outside.

Arterial Occlusive Diseases↗
PubMed1987

Involvement of a nucleolar component, perichromonucleolin, in the condensation and decondensation of chromosomes.

A component of the nucleolar material, perichromonucleolin (PCN), was identified by a specific antiserum against nucleoli obtained from a scleroderma patient. The distribution and changes of PCN during the mitotic cycle were followed using this antiserum and indirect immunofluorescence microscopy. Based upon the behavior of PCN during mitosis, it could be differentiated into chromosomal and nonchromosomal portions. During prophase the former gradually associates with the surface of the condensing chromosomes and forms the coat or pellicle around the metaphase and anaphase chromosomes. This pellicle PCN is carried by the anaphase chromosomes to the daughter nuclei. During the time from telophase to interphase, the pellicle PCN dissociates from the decondensing chromosomes and is incorporated into the new nucleoli. The nonchromosomal PCN, after the breakdown of the nuclear membrane, distributes in the cytoplasmic region around the condensed chromosomes and diffuses into the cytoplasm during anaphase. Preliminary biochemical analysis by immunoblotting showed that the PCN consists of two main proteins with molecular masses of 36 kDa and 30 kDa.

Animals↗
PubMed1987

Relationships between ionizing radiation, bone marrow transplantation and leukemogenesis.

Studies of the relationships between ionizing radiation, bone marrow transplantation and leukemogenesis were carried out in 343 LACA mice. The recipients (female) were given whole-body irradiation with 7 or 8 Gy of Co-60 gamma-rays, while the donors (male) were given whole-body irradiation with 3, 1.5, 0.5, 0.1, 0.05 and 0 Gy of Co-60 gamma-rays. Each recipient was intravenously infused with 1-3 X 10(7) of the mixed marrow cells of donors. In the result, the average incidence of surviving over 1 month was 86% in the recipients. Myelocytic leukemia developed in all the transplanted groups, the average incidence being 88.5%. Leukemia was observed in 1.5-2.5 months after transplantation in the recipients receiving marrow cells from donors exposed to 3 Gy, but in 5-8 months in other groups. It was demonstrated by the analysis of Y-chromosome that the leukemic cells were derived from the donor's marrow cells. The results suggest that marrow transplantation for the mice irradiated by Co-60 gamma-rays of lethal dose can protect them from death, but promote the development of leukemia. Radiation can induce production of factors which lead to leukemic transformation of engrafted normal marrow cells in the irradiated mice; the direct damage of DNA caused by radiation is not the unique factor that gives rise to leukemia.

Animals↗
PubMed1987

Intimal response of saphenous vein to intraluminal trauma by stimulated angioscopic insertion.

Endothelial damage after simulated angioscopic insertion was evaluated in 22 dogs by radioimmunoassay of endogenous 6-keto-prostaglandin F1 alpha (stable product of prostacyclin produced by the endothelium) by means of a closed perfusion system and scanning electron microscopy. In 20 dogs, a 1.7 mm diameter polyethylene tube similar in size and physical characteristics to a commercially available angioscope was passed once into the distal venotomy site and out of the proximal venotomy site for a total distance of 15 cm in the left saphenous vein (group A) and 10 times in both directions in the right saphenous vein, destroying all valves (group B). The vein segments were examined immediately after simulated angioscopic insertion and at intervals of 2, 3, and 4 weeks. The remaining two dogs were used as control animals to establish baseline prostacyclin production. All veins were patent when harvested. Scanning electron microscopy revealed globular and contracted endothelial cells in some areas of group A veins, whereas partial longitudinal absence of endothelial cells was noted in group B veins. Intimal coverage was complete by 2 weeks in group A veins and between 3 and 4 weeks in group B veins. Prostacyclin synthesis of group B veins was significantly less than that of group A at day 1 and at 2 weeks after operation (p less than 0.05), reaching that of control vein synthesis by 4 weeks. This study suggests that simulated angioscopic trauma of the luminal surface of the canine saphenous vein had no negative effect on early patency.

6-Ketoprostaglandin F1 alpha↗
PubMed1987

Direct vision valvulotomy for nonreversed vein graft.

A new and easy technique using an angioscope in a nonreversed, isolated vein bypass is suggested herein. Direct vision valvulotomy with an angioscope in nonreversed vein graft saves operating time, prevents tearing of the vein wall and inaccurate incision of the valves.

Evaluation Studies as Topic↗
PubMed1987

Direct vision valvulotomy in in situ venous bypass.

The autogenous saphenous venous bypass is accepted as an optimal procedure for distal arterial reconstruction. However, serious complications, including incomplete valvulotomy, laceration of the venous wall and persistent arteriovenous communications, are found in in situ bypasses. To avoid these complications, a new and simple technique using an angioscope in the in situ venous bypass has been developed. Angioscopy prevents tearing of the vein wall and avoids inaccurate incision of the valves.

Endoscopy↗
PubMed1986

Neutron field measurements at the Aladdin Synchrotron Light Source.

The neutron field near the inflector of the 800-MeV electron storage ring was studied. Photon-induced neutrons are produced by 100-MeV electrons bombarding the inflector during injection into the synchrotron ring. Neutrons were measured with moderating detectors made of 15 X 15 X 20 cm Lucite blocks and Au activation foils. Detector response was established with a Pu-Be neutron source and a 25.4-cm polyethylene sphere and Au foil detector. The neutron yield was 0.97 +/- 0.14 X 10(12) kJ-1. For 1.38 W of electron pulse power, the dose equivalent rate 1 m aside and 1 m above the inflector was 4.35 +/- 0.47 mu Sv s-1 and 3.13 +/- 0.23 mu Sv s-1, respectively. A measured dose equivalent transmission curve for polyethylene yielded an attenuation coefficient of 15.7 m-1.

Electrons↗
PubMed1986

The competence and bacteriologic effect of the telescoped intestinal valve after small bowel resection.

In 20 dogs the distal one-third of the small intestine and the proximal 10 cm of the ascending colon were resected. Bowel continuity was established by the telescoping technique to create an intestinal valve in ten dogs (group A) and by conventional end-to-end anastomosis in ten dogs (group B). Diarrhea and weight loss were similar in both groups. The ileal bacterial growth was significantly higher than the jejunum in group A (P less than 0.001) but not in group B. The jejunal bacterial growth in group B was significantly higher than that in group A (P less than 0.01). Intestinal transit times were 212 +/- 16.0, 219 +/- 152.4, and 163 +/- 85.8 minutes for normal dogs, groups A and B respectively. The competence of the normal ileocecal valve, the telescoped valve, and conventional anastomosis were 56 +/- 1.7, 49.9 +/- 17.4 and 13.2 +/- 7.8 cm of barium, respectively. Artificial intestinal valve formed by the telescoping technique is safe, simple, and effective in reducing bacterial overgrowth in the jejunum and appears to prolong intestinal transit time.

Animals↗
PubMed1986

Patterns of pannus growth of the expanded polytetrafluoroethylene vascular graft with special attention to the intimal hyperplasia formation.

Serial histologic observations of the healing process of expanded polytetrafluoroethylene (PTFE) vascular grafts in dogs were performed. The common iliac arteries of 12 mongrel dogs were replaced with a 2-cm segment of 6 mm PTFE graft, bilaterally. The grafts were studied microscopically after the animals were killed at 4, 8, 12, 16, 20, and 24 weeks. All the grafts remained patent up to 24 weeks. Special attention was paid to the histological characteristics of pannus growth, which were divided into two types: smooth appearing and irregular. The former type was characterized by smooth, thinner connective tissue growth along the graft, and the latter was defined as irregular-shaped pannus containing large and small thrombi. Only pannus of the smooth type showed similar growth patterns and growth rates. These findings suggest essentially that pannus develops smoothly from both ends of the graft; however, thrombi disturbed this growth pattern. In 24 grafts, eight nodular lesions of the pannus (greater than 500 mu in height) were found: five distally and three proximally. All eight lesions were found within 3 mm of the anastomoses. Among these eight lesions, five were on the completely healed pannus, and the remainings were all on the irregular pannus. This suggests that thrombi organization followed by nodular lesions are major offending factors that lead to the formation of intimal hyperplasia.

Animals↗