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Biomedical subjects

H Ahn

Publications and source records attributed to H Ahn.

10 recordsLinked to original sources
PubMed1991

Thoracic aortic aneurysm associated with aortitis--case reports and histological review.

Ten cases of post-inflammatory aneurysm of the thoracic aorta were studied morphologically using aortic wall and aortic valve tissue resected during the surgical repair of the lesions. Four cases of aortic aneurysm in Behcet's disease showed massive perivascular infiltration of the lymphocytes and plasma cells in adventitia and vasa vasorum. Fibrous obliteration of the vasa vasorum was seen, and neutrophilic infiltration was also associated in two cases with recurrent prosthetic valve failure. Three cases of aortic aneurysm associated with Takayasu's arteritis showed similar histologic features, but giant cells and histiocytic reactions were additional findings. Plasma cell infiltration was more pronounced compared to the Behcet's aortitis. One case of luetic aortitis showed a non-specific chronic inflammatory reaction with florid endothelial cell proliferation. One case of ankylosing spondylitis showed fibrous thickening at the periannular portion of the aortic valve cusps, but this finding was also seen in an aortic valve of a patient with Behcet's disease. One case without any disease association showed similar features of chronic inflammation with granuloma formation. The findings suggest that they have similar histologic features indistinguishable in terms of the clinical disease association, but a granulomatous reaction could be expected in Takayasu's arteritis.

Adult↗
PubMed1991

[Antigenic localities in the tissues of Metagonimus yokogawai observed by immunogoldlabeling method].

In order to determine the antigenic localization in the tissues of the adult Metagonimus yokogawai, immunogoldlabeling method was applied using serum immunoglobulins(IgG) of cats which were infected with isolated metacercariae from Plecoglossus altivelis. The sectioned worm tissue was embedded in Lowicryl HM 20 medium and stained with infected serum IgG and protein A gold complex(particle size: 12 nm). It was observed by electron microscopy at each tissue of the worm. The gold particles were observed on the tegumental syncytium as well as cytoplasm of tegumental cells and epithelial lamella of the caecum. The gold particles were not observed on the basal lamina of the tegument, interstitial matrix of the parenchyma, the muscle tissue and mitochondria of the tegument. The gold particles were specifically labeled in the secretory granules in the vitelline cells. They were also labeled on the lumen of bladder and egg shell. The above findings showed that antigenic materials in the tissue of adult worms were specifically concentrated on the tegumental syncytium as well as cytoplasm of tegumental cells and epithelial lamella of the caecum.

Animals↗
PubMed1990

A moving-actuator type electromechanical total artificial heart--Part II: Circular type and animal experiment.

A new type of electromechanical total artificial heart (TAH) based on circular rolling-cylinder mechanism was developed to overcome critical problems in motor-driven artificial hearts such as large size and difficulties in fitting the heart to atrial remnants and arterial vessels. Its performance and reliability were evaluated in mock circulation and in an animal implant experiment. The total weight and volume of the pump is 650 g and 600 mL, respectively. This new pump was implanted in a calf for total heart replacement and 96 h of survival was achieved. The whole system, including pump, controller, and control algorithm performed well enough to improve the prospect of eventual clinical application of our TAH system.

Animals↗
PubMed1989

Intra-aortic balloon counterpulsation with special reference to determinants of survival.

From 1981 through 1985 intra-aortic balloon counterpulsation (IABP) was required by 90 patients on a total of 91 occasions. They included 85 (3.1%) of the 2751 patients undergoing open-heart surgery during that time. IABP was used preoperatively in 13 cases, to assist weaning from cardiopulmonary bypass in 64, postoperatively in nine, and without cardiac surgery in five cases. Complications arose from IABP in 24/90 patients (27%). The overall short-term survival rate following IABP was 61%, and the long-term (mean 23 months) rate was 51%. Early recovery of cardiac function was the main determinant of survival. Female sex, renal failure and postinfarction ventricular septal defect and mitral incompetence were over-represented among the nonsurvivors. IABP therefore is useful in reversible left ventricular dysfunction, whereas inadequate perfusion of vital organs with potential for failure of more than one organ system implies diminished likelihood of survival.

Aged↗
PubMed1989

Demonstration of species-specific and cross reactive components of Paragonimus westermani crude worm antigen by EITB.

Enzyme-linked immunoelectrotransfer blot (EITB) using crude worm antigen of adult Paragonimus westermani was performed for human patients sera to identify the species-specific components. Crude antigen was obtained by homogenizing and centrifuging 24-week old adult worms at 10,000 rpm for 60 minutes in phosphate buffered saline (PBS, pH 7.2) containing phenyl methyl sulfonyl fluoride (PMSF). Gradient sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was performed and blotted electrophoretically onto a sheet of nitrocellulose paper. The sheet was cut into strips and exposed to sera diluted 1: 200 with PBS. SDS-PAGE showed 26 protein bands ranging 229 to 10 kDa. Of them 229, 91, 60, 50, 35-31, 27, 25, 21, 17, 11 and 10 kDa components showed positive reaction with serum antibody of patients with P. westermani. Sera of patients infected with Clonorchis sinensis reacted with 35-31, 19, and 11 kDa bands. Human sera from cysticercosis and diphyllobothriasis cases showed non-specific cross reactions with 229, 35-31, 27, 25 and 17 kDa bands. Protein bands of 91, 60, 21 and 10 kDa showed strong positive reaction without cross reactions with sera from other helminthic infections.

Animals↗
PubMed1989

Laser Doppler flowmetry in experimental mesenteric vascular occlusion.

The performance of the laser Doppler-signal (measuring blood flow) and the direct current-signal (measuring the amount of backscattered light) were studied in isolated segments of feline small intestine during arterial or venous occlusion. Following total arterial or venous occlusion, the LD-signal rapidly fell to 16% and 29% of control values, respectively. The DC-signal decreased significantly (to 78% of control, p less than 0.001) in response to venous occlusion but did not change significantly following arterial occlusion. After total venous occlusion, the amount of backscattered light was sometimes insufficient to allow flow measurement, probably due to high light absorption in the congested tissue. After ligation of the vascular stalk, the LD-signal soon decreased to 10-15% of control but did not reach the baseline until 4-6 hours. It is suggested that this residual LD-signal is caused by activity in the muscularis layer in the early phase of intestinal infarction.

Animals↗
PubMed1977

Neurometrics.

Explore the source record for details and available documents.

Aged↗
PubMedDate not supplied

A tether-free, moving actuator total artificial heart.

An electromechanical moving-actuator TAH was developed and implanted for 5 days in a calf experiment. The efficiency and durability were further improved using pendulous motion of the actuator. This new pendulum pump has a circular motion produced by gear mechanisms connected to the motor. It has a height (from valves to housing bottom) of 7 cm and centrally directed inlets and outlets for good fittability. Active filling (-10 mmHg) inside inner blood sacs was produced by the suction effects of the outer sacs attached to a moving actuator. Two acute animal experiments were performed using the pendulum pump with a Coridale sheep (50 kg weight), and a male calf (70 kg weight). A test was made of 30 minutes of tether-free operation of the implanted pendulum pump inside the small chest of the calf. The pump shows the engineering feasibility of the implantable electrical TAH inside a human chest cavity.

Animals↗
PubMedDate not supplied

Intraoperative assessment of blood flow and tissue viability in small-bowel ischemia by laser Doppler flowmetry.

Laser Doppler flowmetry (LDF) was used for intraoperative assessment of blood flow and tissue viability in 23 patients with small-bowel ischemia, and the signal levels in ischemic bowel were compared with previously obtained reference values from normal ileum and jejunum. The average LD signal was 6.8 +/- 2.9 V in nonischemic bowel, 0.3 +/- 0.2 V in segments with macroscopically irreversible ischaemia and 2.1 +/- 1.2 V in segments with clinically uncertain viability. In 12 cases with strangulated bowel it was possible, following LDF, to avoid resecting nine of ten bowel segments with clinically uncertain viability. In four of the six patients with mesenteric vascular occlusion, LDF indicated that clinical judgement had underestimated the extent of severe ischemia. Among the five cases of iatrogenic ischemia there was one failure, with postoperative irreversible ischemia and anastomotic leakage. LDF is concluded to be a useful method for intraoperative assessment of intestinal blood flow in patients with small-bowel ischemia and it provides substantial information on tissue viability affecting surgical strategy.

Adolescent↗