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Biomedical subjects

Y Kang

Publications and source records attributed to Y Kang.

At least 217 records · Page 12Linked to original sources
PubMed1991

Clinical evaluation of autotransfusion during liver transplantation.

The clinical suitability of intraoperative autotransfusion was evaluated in 25 patients undergoing orthotopic liver transplantation using a Cell Saver #4 (Haemonetics) with acid-citrate-dextrose anticoagulation. In the first 14 patients (phase 1), biochemical, hematologic, coagulation, and semiquantitative bacteriologic studies were performed from the collected blood, processed blood, and patients' blood before and after 500 mL of autotransfusion. The acid-citrate-dextrose solution produced adequate anticoagulation, and the system effectively removed most of the potassium, red blood cell fragments, plasma free hemoglobin, bilirubin, coagulation factors, platelets, and fibrin degradation products. Autotransfusion (500 mL) did not alter coagulation, electrolyte balance, and hematologic findings in recipients except for a clinically insignificant increase in plasma free hemoglobin. Seventeen of 56 samples of the collected blood or processed blood were positive for coagulase (-) Staphylococcus (occasional or rare), but blood cultures before and after autotransfusion were negative in all patients. In the next 11 patients (phase 2), a quantitative bacteriologic study was performed from the collected blood, processed blood, skin, bile duct stump, peritoneal cavity, and room air using a mock reservoir. The processed blood was not transfused. All blood cultures from the patients were sterile. However, coagulase (-) Staphylococcus or Bacillus sp was seen in two cultures from skin, three from the processed blood, and three from air, suggesting that room air and skin were the sources of contamination. When the patients of the two phases of study were compared, postoperative blood cultures were all sterile, and renal function was similar. Therefore, autotransfusion appears to be clinically acceptable during liver transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Pharmacokinetics and pharmacodynamics of doxacurium in normal patients and in those with hepatic or renal failure.

We determined the pharmacokinetics and duration of action of a bolus dose of doxacurium (15 micrograms/kg) in 27 patients anesthetized with isoflurane and nitrous oxide. Nine patients had normal renal and liver functions and were undergoing a variety of surgical procedures, nine were undergoing cadaveric kidney transplantation because of end-stage renal disease, and nine were undergoing cadaveric liver transplantation because of end-stage hepatocellular disease. Plasma concentrations of doxacurium were measured for 6 h after administration using a sensitive and specific capillary gas chromatographic assay. Plasma concentration versus time data were analyzed by a noncompartmental method based on statistical moments. Neuromuscular blockade was assessed by measuring the electromyographic evoked response of the adductor pollicis muscle to train-of-four stimulation of the ulnar nerve. The degree of neuromuscular blockade after doxacurium administration was described as the percent of control of the first train-of-four response. The pharmacokinetic variables were (normal vs hepatic failure vs renal failure, respectively): volume of distribution at steady state (220 +/- 110 vs 290 +/- 60 vs 270 +/- 130 mL/kg [mean +/- SD]), plasma clearance (2.7 +/- 1.6 vs 2.3 +/- 0.4 vs 1.2 +/- 0.7 mL.kg-1.min-1), mean residence time (95.2 +/- 57 vs 129.4 +/- 30 vs 270 +/- 210 min), and elimination half-life (99 +/- 54 vs 115 +/- 31 vs 221 +/- 156 min). Plasma clearance and mean residence time differed significantly between patients with renal failure and control patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Cerebral blood flow patterns at major vessel bifurcations and aneurysms in rats.

Cerebral arterial bifurcations in rats were treated to induce cerebral aneurysms experimentally, and flow patterns of latex particles introduced under a constant flow rate were analyzed with a 16-mm cine-camera and videocassette recorder. Cerebral aneurysms were produced by ligating one common carotid artery, inducing experimental hypertension, and feeding the animals beta-aminopropionitrile. After perfusion and fixation, samples of cerebral arterial bifurcations with shallow invaginations and with small aneurysms were obtained and used for analysis. Bifurcations in rats without experimental treatment were used as control specimens. Flow studies in the control bifurcations showed that the apical intimal pad, not the apex itself, acted as the flow divider. Small particles tended to accumulate at the region just distal to the apical intimal pad, where the initial aneurysmal changes are known to occur. This indicates stagnation of flow at that site. In the bifurcations with shallow invaginations and small aneurysms, a marked pressure gradient was present at the proximal end of the aneurysm orifice. A tendency for stagnation of small particles near the aneurysm wall was also observed. The wall shear stress was highest at the distal end of the aneurysmal orifice, which may be responsible for the development of these lesions.

Animals↗
PubMed1991

[Kinetic observation on BRC immune function of patients with epidemic hemorrhagic fever].

The RBC immune function of 88 patients with epidemic haemorrhagic fever (EHF) was examined kinetically with complement-labeled yeast method established by Guo Feng. The results showed that the percentage of RBC c3b receptor rossette, activity of RCIA-enhancing factor and c3 in sera of patients during the 3 different phases of EHF were markedly lower than those of the normal controls, while the percentage of RBC IC rossete, activity of RCIA-inhibiting factor and CIC in sera of the patients were manifestly higher (P less than 0.01). The change of all the indices observed above was most apparent in oliguric phase. This suggested that RBC immune function is lowered in the process of EHF.

Adult↗
PubMed1991

[The effect of free radicals on the rabbit articular chondrocytes in monolayer culture].

By using monolayer culture technique, the effect of endogenous free radicals on rabbit articular chondrocytes was studied. The free radicals were provided through the action of xanthine oxidase (XO) on xanthine (X). The amount of DNA in chondrocytes was measured with ethidium bromide method for direct fluorometric estimation of DNA. The synthesis of proteoglycan (PG) was assayed through 35S-Na2SO4 incorporation followed by inverted microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results indicated that chondrocytes could be damaged by endogenous free radicals generated by the action of XO on X, and these free radicals may be related to the pathogenesis of cartilage aging, degeneration, degenerative joint disease and arthritis.

Animals↗
PubMed1991

[Da cheng qi tang on 45Ca content of the isolated colon smooth muscle from experimental colon obstruction rats].

Da Cheng Qi Tang (DCQT) is a classical prescription of Chinese medicine for treatment of acute intestinal obstruction. In this paper, the isolated colon smooth muscle from normal and experimental colon obstruction (CO) rats were used to study the effect of DCQT on 45Ca content. The results showed that the 45Ca content on isolated colon smooth muscle (microns/g wet tissue, mean +/- S) was 0.043 +/- 0.009 in the normal and 0.057 +/- 0.012 in those treated by DCQT respectively. The content of 45Ca in CO was higher than the normal, DCQT can reduce the content of 45Ca in CO. It is known that the higher level of intracellular CA++ is related to the formation and the development of acute intestinal obstruction. The inhibitory effect of DCQT on 45Ca content may play an important role in the treatment of acute colon obstruction.

Animals↗
PubMed1990

Electrophysiological properties of pedunculopontine neurons and their postsynaptic responses following stimulation of substantia nigra reticulata.

Membrane properties and postsynaptic responses to stimulation of the substantia nigra reticulata (SNr) of the neurons in rat pedunculopontine nucleus (PPN) were studied in an in vitro parasagittal slice preparation using intracellular recording techniques. Based on electrical membrane properties, PPN neurons were classified into 3 types (types I, II and II). The unique feature of the type I neuron was the low threshold calcium spike while the type II neuron had various inward and outward rectifications. The type III neuron showed no such features as those observed in type I or II neurons. Some recorded neurons were intracellularly labeled with biocytin to study their morphology, and their transmitter phenotype was investigated by immunocytochemistry for choline acetyltransferase (ChAT). The type I and III neurons were found to be non-cholinergic, but 50% of the labeled type II neurons were immunopositive for ChAT. Morphological features of type II neurons were also different from type I or III neurons. The soma of the type II neuron was almost always more than twice as large as that of type I and III neurons. Inhibitory postsynaptic potentials (IPSPs) were induced in all 3 types of PPN neurons following stimulation of SNr. SNr-induced IPSPs were usually followed by a slow depolarizing potential from which rebound spikes were triggered. These rebound excitations were found only in type I and II neurons. These data indicate that heterogeneous groups of neurons exist in the PPN in terms of morphology, transmitter phenotypes and electrical membrane properties.

Action Potentials↗
PubMed1990

[Experimental study on the mechanism of injury and proliferation of intima in the process of cerebral aneurysm development].

Under the hypothesis that cerebral aneurysms develop partly because of defective or decreased healing process at the site of intimal injury, namely at the site of cerebral arterial bifurcation, following experiments were performed. Experiment (1): Rats were treated with ligation of one common carotid artery and ligation of posterior branches of renal artery on both sides to induce cerebral aneurysms. Three months after the treatment, the contralateral carotid artery was ligated. Two months after the ligation, they were sacrificed and examined under light and electron microscopes. In 7 of 11 bifurcations which developed small cerebral aneurysms, prominent intimal thickening with proliferated smooth muscle cells and collagen was observed in the lumen of aneurysms. In 3 of 7 bifurcations which showed no aneurysmal development, apparent intimal thickening was also found at the site where aneurysms were expected to grow. In the group treated for inducing cerebral aneurysms but not ligated the contralateral carotid artery, none of 12 bifurcations with or without aneurysms showed such intimal thickening. Experiment (2): Rats were treated for inducing cerebral aneurysms. Three months after the treatment, reserpine was injected (0.75 mg/Kg B.W./day intraperitoneally) for 2 weeks. At the next day of the last injection, they were sacrificed and examined under the light microscope. In 6 of 12 bifurcations which developed small cerebral aneurysms, prominent intimal thickening was observed in the lumen of aneurysms. In 2 of 3 bifurcations which showed no aneurysmal development, apparent intimal thickening was also found at the site where aneurysms were expected to grow. In the group treated for cerebral aneurysms but not injected reserpine, none of 10 bifurcations with or without aneurysms showed such intimal thickening. Experiment (3): Rats were treated for inducing cerebral aneurysms. Two weeks after the treatment, FSF (fibrin stabilizing factor, known as blood coagulation factor XIII) was injected (10 U/100 g B.W./day, intravenously) for 5 days. Twelve days after the start of injection, they were sacrificed and examined under light and electron microscopes. In 11 of 20 bifurcations which developed small cerebral aneurysms, prominent intimal thickening was observed in the lumen of aneurysms. In the most advanced cases, the lumen of aneurysms were completely filled with proliferated smooth muscle cells and collagen. In 5 of 10 bifurcations which showed no aneurysmal development, apparent intimal thickening was found at the site where aneurysms were expected to grow. In the group treated for inducing cerebral aneurysms but not given FSF, none of 15 bifurcations with or without aneurysms showed such intimal thickening.

Animals↗
PubMed1990

Ionization and hemodynamic effects of calcium chloride and calcium gluconate in the absence of hepatic function.

Serial serum ionized calcium concentrations were measured before and after administration of either calcium chloride or calcium gluconate during the anhepatic stage of liver transplantation in 15 patients to determine the release of ionized calcium in the absence of hepatic function. When hypocalcemia (Ca++ less than 0.8 mM) occurred during the anhepatic stage, patients were randomly assigned to treatment with chemically equivalent doses of either calcium chloride (10 mg/kg, n = 8) or calcium gluconate (30 mg/kg, n = 7). Serum concentrations of ionized calcium and citrate, hematocrit, arterial blood gas tensions, acid-base state, and hemodynamic profiles were determined before and up to 10 min after calcium therapy. In both groups of patients initial similar and rapid increases in Ca++ (0.98 +/- 0.14 mM in the calcium chloride group and 1.05 +/- 0.10 mM in the calcium gluconate group) were followed by gradual decreases over the next 10 min. Measured hemodynamic values were similar in the two groups, and neither group showed improvement in cardiovascular function after calcium therapy, possibly because of the decrease in preload that occurred during the anhepatic stage. Equally rapid increases in Ca++ after administration of calcium chloride and gluconate in the anhepatic state suggest that calcium gluconate does not require hepatic metabolism for the release of Ca++ and is as effective as calcium chloride in treating ionic hypocalcemia in the absence of hepatic function.

Adult↗
PubMed1990

Study of the elastic skeleton of intracranial arteries in animal and human vessels by scanning electron microscopy.

We studied the elastic skeleton of major cerebral arteries in rats, monkeys, and one human using scanning electron microscopy after hot formic acid extraction followed by freeze-drying. For comparison, we also examined the thoracic aorta and femoral artery of rats. The cerebral arteries of rats had one distinct internal elastic lamina connected to the thin adventitia with sponge-like medial elastic tissue. This internal elastic lamina had fenestrations, which we found to be less frequent in cerebral arteries than in extracranial arteries, and fold-like protrusions into the lumen. This finding has not been recognized before. Such protrusions were more prominent in cerebral arteries than in extracerebral arteries. At the apical intimal pad, the internal elastic lamina appeared to be continuous, making a honeycomb-like structure. The folds and fenestrations were numerous at the apex. There were no essential differences among species. Our study shows that the internal elastic lamina is not a simple sheet but part of the complicated architecture of the elastic tissue of the vessel wall. These differences in the elastic skeleton, including fenestrations and fold-like structures, in various sites of different arteries may explain the development of various localized vascular diseases.

Animals↗
PubMed1990

Effects of blood coagulation factor XIII on the development of experimental cerebral aneurysms in rats.

Pathological and experimental studies have shown that cerebral aneurysms develop in part as a result of injury to the blood vessel wall. One of the peculiar aspects of aneurysm development is a defective proliferative or healing response to such injury. To examine this phenomenon, blood coagulation Factor XIII, which is known to enhance the healing process of wounds in general, was given to rats to induce experimental cerebral aneurysms. The rats were subjected to ligation of one common carotid artery and induction of hypertension, and were fed beta-aminoproprionitrile. Two weeks thereafter, Factor XIII was injected intravenously daily for 5 days (10 U/100 gm body weight/day). Twelve days after the start of Factor XIII injections, the rats were sacrificed and examined under light and electron microscopy. In seven of 12 bifurcations which developed small aneurysms, prominent intimal thickening was observed in the aneurysm lumen. In the most advanced cases, the aneurysm lumen was completely filled with proliferated smooth-muscle cells and collagen. In five of nine bifurcations that showed no aneurysm development, apparent intimal thickening was found at the site where aneurysms might be expected to grow. In the group of rats studied for induction of cerebral aneurysms but not given Factor XIII, none of 11 bifurcations with or without aneurysms showed such intimal thickening. The results indicated that the proliferative response at the sites of aneurysm development was modified by exogenous Factor XIII.

Animals↗