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Biomedical subjects

H Yu

Publications and source records attributed to H Yu.

At least 775 records · Page 43Linked to original sources
PubMed1985

Fever and proximal tubular function in acute pyelonephritis.

The urinary excretion of alpha 1-microglobulin (alpha 1M), beta 2-microglobulin (beta 2M), retinol-binding protein (RBP) and N-acetyl-beta-D-glucosaminidase (NAG) as markers of proximal tubular dysfunction was measured in various forms of urinary tract infections (UTI) and in fever due to non-renal infections. The urinary concentration of these proteins was significantly increased in acute pyelonephritis compared with acute cystitis and asymptomatic bacteriuria. Tubular proteinuria and enzymuria could also be demonstrated in subjects with fever of non-renal origin and corresponded to the findings of pyelonephritis. It is suggested that fever per se is the most likely cause of the tubular proteinuria seen in acute pyelonephritis. In localizing an acute UTI characterization of the urinary protein profile seems to have no advantage over a carefully measured body temperature. The urinary excretion of alpha 1M,beta 2M and RBP were highly correlated, while urinary NAG activity was less correlated to these low-molecular weight proteins. Fibrin degradation product D (FDP-D) was detected in the urines in 60% of the patients with acute pyelonephritis and in one third of those with acute cystitis. The estimation of FDP in urine therefore seems to be of little value in the level diagnosis of UTI.

Acetylglucosaminidase↗
PubMed1985

Purified colicin as cytotoxic agent of neoplasia: comparative study with crude colicin.

Purification of a bacteriocin, colicin, from Escherichia coli HSC10, is described. A 1,800 fold purified colicin was obtained and found to be an acidic polypeptide with a molecular weight of 82,000 daltons. The effect of colicin on bacterial and mammalian cells during the transition from a crude to a pure preparation is given. A turbidimetric assay for bacterial growth inhibition and 3H-thymidine uptake inhibition for measuring the effect on mammalian cells, was used. Colicin HSC10 caused DNA loss from the bacteriocin-sensitive mammalian cells, which increased with dose and time of exposure. Therefore, flow-cytometry, which detects DNA loss from the bacteriocin-affected mammalian cells, was also used to evaluate the bacteriocin potency. Similar quantitative results were obtained to those using 3H-thymidine uptake inhibition, in terms of microgram protein of pure colicin required to affect adversely 50% of the cells. The bacteriocins were found to retain their activity following freezing and thawing, both as crude and pure preparations, against both bacterial and mammalian cells.

Amino Acids↗
PubMed1984

Cluster analysis of chromatographic profiles of urine proteins.

A method to examine and classify the chromatograms of urinary proteins, separated on a fast protein liquid chromatography system, is presented. For the analyses a measure of similarity between chromatogram profiles is defined and this is used to implement a statistical cluster analysis technique for the identification of a system of classification. The resulting classification can be related to a clinical assessment of the proteinuria of the sample urines, which are from patients with various renal disorders.

Chromatography, High Pressure Liquid↗
PubMed1983

Osmotic deformation of red blood cell ghosts induced by carbohydrates.

The osmotic response of bovine red blood cell ghosts to a series of sugars is studied by light scattering. The sealed and right-side-out ghosts are prepared by the procedure of Steck and Kant (Steck, T.L. and Kant, J.A. (1974) Methods Enzymol. 31, 172-180), swollen in a hypotonic phosphate-buffered saline solution and their size and shape determined by elastic and quasielastic light scattering. Different carbohydrates are then added to the suspending medium in order to examine the osmotic responses, and the osmotic deformation of ghosts is shown to be spherically symmetric. Having thus established the deformation behavior, we then rank the osmotic activity of a carbohydrate relative to a standard, i.e., raffinose. It is found that the osmotic response of the ghosts to sucrose is about the same as that to raffinose, and the response to the smaller carbohydrates simply follows the number of carbons in various sugars; glucose and fractose are about 1.7 times less effective than raffinose, and pentaerythritol and meso-erythritol are 2.3 times less effective. Glyceraldehyde, which is 3.6 times less effective than raffinose, is the least effective sugar analog among those that we have tested.

Animals↗
PubMed1983

Urinary protein profiles after burn injury.

A study of the change of urinary protein excretion has been made in 26 patients followed from the time of admission to time of discharge from the Yorkshire Regional Burn Centre (7-200 days). Total protein, IgG and albumin (as indicators of glomerular function) and alpha 1-microglobulin, beta 2-microglobulin, retinol binding protein and N-acetyl-beta-D-glucosaminidase (as indicators of proximal tubular function) as well as the patterns on SDS polyacrylamide gel electrophoresis were examined. Patients were divided into three groups according to their urinary protein profiles. The first group was 3 patients who showed little or no evidence of proteinuria; the second group consisted of 7 patients who showed a mild and transient tubular proteinuria, all of whom recovered normal function within one week. The third group, 16 patients, developed moderate to severe proteinuria usually started as a mixed pattern of glomerular and tubular proteinuria, characterized by the excretion of a high level of total protein. After a few days, this pattern changed to a typical tubular proteinuria and the latter could last for as long as 200 days; in some of these patients a secondary increase of low molecular weight protein excretion occurred either due to a latent renal complication or induced by the administration of aminoglycosides. There is a close correlation between the intensity and patterns of the proteinuria and the severity and clinical progress of the burn.

Acetylglucosaminidase↗
PubMed1983

Alpha-1-microglobulin: an indicator protein for renal tubular function.

A comparison of urinary alpha 1-microglobulin concentrations to the behaviour of other indicators of renal tubular disorders, beta 2-microglobulin, retinol-binding protein and N-acetyl-beta-D-glucosaminidase (NAG) has been made. In acute tubular disorders the concentrations of urinary beta 2M and RBP are highly correlated (r = 0.89) but this is less marked for alpha 1M and beta 2M (r = 0.55) and alpha 1M and RBP r = 0.48. NAG tends to run a parallel course to alpha 1M concentrations but lags behind the recovery of low molecular weight protein reabsorption following injury of the tubular cells. The concentrations of alpha 1M, and in particular its stability at low pH suggest that this protein may be useful in screening for tubular abnormalities and detecting chronic asymptomatic renal tubular dysfunction. Urinary alpha 1M greater than 15 mg/g creatinine is strongly suspicious of a proximal tubular dysfunction. The distinction between pure tubular proteinuria and mixed glomerular and tubular proteinuria requires further analysis.

Adult↗
PubMed1982

Aggregation equilibria of Escherichia coli RNA polymerase: evidence for anion-linked conformational transitions in the protomers of core and holoenzyme.

The aggregation equilibria of Escherichia coli RNA polymerase core and holoenzyme have been studied by velocity sedimentation as a function of [NaCl] both in the presence and in the absence of MgCl2. Effects of other anions (F- and I-), pH, and temperature have also been examined. Diffusion coefficients obtained by quasi-elastic light scattering (QLS) at high and low salt concentrations were used in conjunction with sedimentation coefficients under these conditions to obtain molecular weights of the protomer and aggregates of the core enzyme. At low salt concentration, core aggregates to a tetramer in the absence of MgCl2 and to an octamer in the presence of MgCl2. Some ambiguity exists in the interpretation of the sedimentation and QLS data for holoenzyme. The sedimentation results are consistent with the formation of dimers at low salt, both in the presence and in the absence of MgCl2. In all cases, equilibrium constants were calculated assuming a simple monomer--j-mer stoichiometry. These equilibrium constants are extremely sensitive functions of the concentration and type of monovalent anion. In Cl-, aggregation of both core and holoenzyme begins abruptly when the salt concentration is reduced below approximately 0.2 M (at a protein concentration of approximately 0.30 mg/mL); for core, substitution of I- for Cl- suppresses aggregation while F- enhances aggregation at a fixed anion concentration. No specific effect of monovalent cations (Na+, NH4+) is observed; Mg2+ has no effect on holoenzyme dimerization and has little effect on the salt range of core aggregation, though the stoichiometries of the core aggregates in the presence and absence of Mg2+ differ. Anion effects on these equilibria were modeled by assuming that a class of anion-binding sites on the protomer is not present in the aggregate, so that anion release accompanies aggregation. Analytical expressions for several models of the effect of anions on the aggregation equilibria were derived by using the method of binding polynomials. The salt dependence of the aggregation equilibria in the absence of Mg2+ appears inconsistent with a model in which the anion-binding sites on the protomer are independent (noncooperative), but it is well described by a model in which anion binding to the protomers occurs in a completely cooperative manner. The molecular basis of this apparent cooperative effect of anions on the aggregation equilibria is proposed to be an allosteric effect of anions on conformational equilibria of the protomers of core polymerase and the holoenzyme. Implications of such a salt-dependent conformational transition for the DNA-binding interactions of the enzyme are considered.

Anions↗
PubMed1981

Lateral diffusion of photopigments in photoreceptor disk membrane vesicles by the dynamic Kerr effect.

The lateral diffusion of photopigment molecules in the photoreceptor disk membranes, osmotically swollen into spherical vesicles, has been investigated by dynamic Kerr effect measurements. Upon application of a rapidly reversing bipolar electric field to dilute aqueous suspensions of bovine disk membrane vesicles, the birefringence transient shows a characteristic rise and a deep dip corresponding to the first and second pulses, respectively. The birefringence transient is ascribed to the slowly induced dipole moment caused by electric field induced displacement of the photopigment distribution on the vesicular surface. The lateral translational diffusion coefficient is estimated from the time constant of the slowly induced dipole as D = (3.3 +/- 1.2) X 10(-9) cm2 s-1. When spermine, a cationic tetraamine, is bound to the disk membrane vesicles, the relaxation time of the slowly induced dipole is shown to become longer, indicating that the birefringence mechanism is indeed due to the field-induced photopigment displacement.

Animals↗