Biomedical subjects
Publications and source records attributed to Y Lee.
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The effect of pH on the kinetics of the following transhydrogenation reactions catalyzed by energized and nonenergized submitochondrial particles has been studied: NADH leads to 3-acetylpyridine adenine dinucleotide phosphate (AcPyADP), NADH leads to thionicotinamide adenine dinucleotide phosphate (thioNADP), NADPH leads to AcPyADP, and NADPH leads to thioNADP. The effect of membrane energization on reaction rates can be approximated in the case of NADH leads to AcPyADP and thioNADP transhydrogenations, or equaled in the case of NADPH leads to AcPyADP and thioNADP transhydrogenations by lowering the assay pH to less than or equal to 6.0. For the reactions NADH leads to AcPyADP and thioNADP under energy-linked conditions, substrate Km values are lowest and Vmax values are highest at pH 7 to 7.5, the optimum pH for mitochondrial energy transduction processes. Under non-energy-linked conditions, however, Km values were lowest and Vmax values were highest at the most acid conditions (pH = 5.5) examined. Plots of ln (Vmax/Km) (an index of enzyme-substrate affinity to form a complex) versus pH showed the highest affinity at pH 7 to 7.5 for energy-linked conditions. Similar plots for non-energy-linked conditions. Similar plots for non-energy-linked conditions. Similar plots for non-energy-linked conditions showed a sharp and linear increase in the value of ln (Vmax/Km) as the assay pH was lowered from 8.5 to 6 to 6.5. This was followed by a less steep line down to pH 5.5, with a clear break at pH 6 to 6.5. These results suggested the involvement of ionizable group(s) with pK value(s) at pH 6 to 6.5 affecting enzyme-substrate binding under non-energy-linked conditions. An analogous mechanism, possibly by way of proton-induced conformation change of the transhydrogenase enzyme (EC 1.6.1.1), might be involved in increasing enzyme-substrate affinity and consequently the rate of transhydrogenation under energy-linked conditions.roton-induced conformation change of the transhydrogenase enzyme (EC 1.6.1.1), might be involved in increasing enzyme-substrate affinity and consequently the rate of transhydrogenation under energy-linked conditions.
This is a retrospective and all inclusive study of 925 patients who had isolated lymph node biopsies for diagnosis from 1973 to 1977. Overall, 60% of the nodes had benign lesions, 28% carcinoma, and 12% lymphoma. The comparable figures for abdominal nodal biopsies were 63%, 33% and 4%; for intrathoracic nodes, 73%, 26% and 1%; for peripheral nodes, 56%, 29% and 15%. Detailed distribution according to specific site of nodal biopsy, histological subtypes, age, and sex of patients are presented. Statistically, age is the most important factor useful in estimating the probability of whether the lymphadenopathy is due to a benign or malignant process.
Huge mediastinal masses in infants are often difficult to diagnose, and thymic enlargement must be considered in each instance, especially when the mass is located anteriorly. In the patient reported on here, the mass occupied approximately 60% of the chest cavity, and surgical intervention was required to establish the precise histological diagnosis. This proved to be massive hyperplastic thymus.
A method for the simultaneous enumeration of human lymphocyte subpopulations was developed by mixing lymphocytes, sheep red blood cells and immunobeads. Thymus-dependent lymphocytes (T cells) are detected by rosette formation with AET-treated sheep blood cells, and thymus-independent lymphocytes (B cells) are identified by rosette formation with polyacrylamide gel coated with antibody specific to both light chains (chi and lambda) of immunoglobulin. The major advantage of this technique is that it is simple, convenient and reproducible. This method also detects lymphocytes possessing both T and B cell markers (double-marker lymphocytes). Three different types of rosettes are distinquishable under light-microscopic observation, and this method may be valuable in clinical use.
A simple, reproducible method for preservation of lymphocyte rosettes in agarose-gel as supporting medium had been developed. The method allows many test samples to be stored and examined under similar conditions, and rosette-forming cells to be identified by the morphologic features.
This paper describes a method for the simultaneous determination of human thymus-dependent lymphocyte (T cell) and thymus-independent lymphocyte (B cell) populations by mixing lymphocytes, sheep red blood cells, and immunobeads. This method also detects lymphocytes possessing both T and B cell markers. T cells are detected by rosette formation with AET-treated sheep red blood cells and B cells are identified by rosette formation with polyacrylamide gel coated with antibody specific to immunoglobulin classes. The major advantages of this technique is that it is simple, convenient, and reproducible. Three different types of rosettes are distinguishable under light microscopic observation. The detection of double marker lymphocytes, using this combined technique, may have further application in clinical investigation.
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An enzymatic assay method for the microdetermination of unbound bilirubin in newborn icteric sera is described. Unbound bilirubin is oxidized to colorless compounds by peroxidase in the presence of hydrogen peroxide derived from glucose by the mediation of glucose oxidase. In this method, the bilirubin is not significantly degraded before the addition of peroxidase, in contrast to the method using hydrogen peroxide. The oxidation rate is determined by spectrophotometry and chloroform extraction is eliminated. The unbound bilirubin concentration can be determined from the initial oxidation velocity of total bilirubin. The Michaelis constant, KM, was approximately 20 micrometer. The coefficient of variation for icteric serum determination was 4.4--6.5%. The concentration of unbound bilirubin was reduced after five days of storage at -20 degrees C. The bilirubin-albumin affinity was studied with purified albumin and adult serum. The dissociation constants were 2 x 10(-8) M and 5 x 10(-9) M, respectively, at bilirubin/albuminor molar ratios below 1.0. Clinically, serum samples from 75 icteric newborn infants were analysed, and the sera of premature infants were found to have remarkably high levels of unbound bilirubin compared to those of fullterm infants. The sera of a Rhesus immunization infant and an ABO incompatibility infant were remarkably higher than that of the nonhemolytic icteric sera. The unbound bilirubin concentration was also affected, in an in vitro study, by the addition of hemolysate.
In order to elucidate the role of lysolecithin in membranes, we have examined the effect of lysolecithin on the structure and permeability of lecithin bilayer membranes. Small L-alpha-dimyristoyllecithin (DML) vesicles with myristoyllysolecithin (MLL) incorporated as well as small L-alpha-dipalmitoyllecithin (DPL) vesicles with palmitoyllysolecithin (PLL) were studied by nuclear magnetic resonance (NMR) methods at temperatures both above and below the alpha-gel in equilibrium liquid crystalline phase transition temperature (Tc) and as a function of the concentration of the incorporated lysolecithin. Europium (III) ion was used as a probe to measure the permeability of the vesicular bilayer membrane. At temperatures below Tc, these vesicles were found to be extremely permeable to europium (III) ions. The ion translocation was found to be too fast to be measured by the NMR method under these conditions. However, above the phase transition temperature the ionic permeability decreases to a rate which could be conveniently monitored, and the permeability was shown to increase with temperature and lysolecithin concentration. Analysis of the lysolecithin concentration dependence suggests the formation of ion channels within the lipid bilayer involving four lysolecithin molecules. The data below Tc suggest a phase separation below the phase transition temperature of the host lipid, leading to the formation of patches of lysolecithin molecules within the lecithin matrix. These lysolecithin clusters are presumably long-lived under these conditions and are sufficiently structurally perturbed or disordered to serve as channels for rapid ion permeation.
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Reports in the literature that study the frequency of cancer in individual who have had their tonsils or appendix or both removed are reviewed. Some investigators found a high incidence of solid cancers - in particular, breast and colon neoplasms - in female patients who have had appendectomy, but others disagreed. The association of tonsillectomy and/or appendectomy with the later development of malignant lymphomas is not proven.
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