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Biomedical subjects

A W Yu

Publications and source records attributed to A W Yu.

At least 37 records · Page 2Linked to original sources
PubMed1997

Dialysis adequacy of Asian patients receiving small volume continuous ambulatory peritoneal dialysis.

The usage of three x 2 liter daily exchanges is adopted as the standard CAPD regime in Hong Kong over the last 10 years due to budgetary constraint. This dialysis prescription is considered suboptimal in Western standard. However, the necessity of maintaining Kt/V > 1.7 for CAPD dialysis adequacy is not unanimously agreed. We performed a cross-sectional study of 117 patients on CAPD. Seventy-eight percent of our patients had 3 x 2 liter daily exchange while the rest had 4 daily exchanges. Fifteen percent of patients were diabetic. Patients with Kt/V < 1.7 were similar to those with Kt/V > 1.7 in age, duration of CAPD, BUN, plasma creatinine, albumin, peritonitis rate, and incidence of hypertension. Patients with Kt/V > or = 1.7 had higher hemoglobin, higher nPCR, more residual renal function; and more of them received 4 daily exchanges. Their peritoneal permeability did not differ. Their employment and rehabilitation status was also similar. Our 5-year survival was 79% despite a lower Kt/V. Notably, the protein catabolic rate of our patients was higher than that in Western patients. This is likely due to dietary difference. Our study suggests small-volume dialysis may be acceptable in Asian population with smaller body size given the financial constraint.

Adult↗
PubMed1996

Neutrophil attractant protein-1 interleukin 8 and its autoantibodies in IgA nephropathy.

Human neutrophil attractant protein-1/interleukin 8 (IL-8) has been shown to activate neutrophils to degranulate in vitro and to be a potent chemotactic agonist for neutrophils and lymphocytes in vitro and in vivo. There is accumulating evidence that neutrophils are involved in inflammatory injury in IgA nephropathy (IgAN). We studied the serum levels of IL-8 and its autoantibodies of the IgA or IgG class in 36 patients with IgAN in comparison with 31 healthy controls and 26 patients with other primary glomerulonephritides (CGN). Interleukin 8 was more frequently detected in sera of patients with IgAN and their serum levels were significantly higher than those of healthy controls. The free IL-8 autoantibodies of the IgA, but not IgG class, were more frequently detected in patients with IgAN and their serum levels were significantly elevated compared with both groups of controls. The complexed IL-8 autoantibodies of either class were not different among the three groups of subjects. Again the ratio of free to complexed IL-8 autoantibodies of the IgA class was raised in patients with IgAN. Histologic examination revealed increased polymorphs and monocyte/macrophage infiltration in IgAN compared with other glomerulonephritides. When the serum levels of IL-8 and IL-8 autoantibodies were compared between IgAN patients with milder pathology and those with more severe pathology, the latter group had significantly higher serum levels of free and complexed IL-8 autoantibodies of the IgA class. These observations suggest a possible role for IL-8 and its autoantibodies of the IgA class in the inflammatory process of IgAN. These autoantibodies may provide a clinically useful marker for the diagnosis of disease severity.

Adult↗
PubMed1996

Serologic study of immunoglobulin A-fibronectin aggregates in immunoglobulin A nephropathy.

The immunoglobulin A (IgA)-fibronectin aggregates, detected by enzyme-linked immunosorbent assay using either antifibronectin or collagen I as binding protein, were previously found to be raised in the circulation of patients with IgA nephropathy (IgAN). It has been suggested that IgA-fibronectin aggregates are involved in the pathogenesis and that the plasma IgA-fibronectin level may even be of diagnostic value in IgAN. Nevertheless, a recent report has questioned the specificity of these assays as plasma IgA may interact with immobilized IgG and these assays detect not only IgA-fibronectin, but also total plasma IgA. These doubts render the interpretation of raised IgA-fibronectin aggregates in IgAN impossible. We isolated total IgA, in plasma by jacalin-agarose. Monomeric and polymeric IgA1 were distinctly separated by fast protein liquid chromatography. When the fast protein liquid chromatography fractions were analyzed for IgA-fibronectin using the antifibronectin capture assay, increased optical density values were predominantly observed in polymeric IgA but not in monomeric IgA. Similar findings were found when the fast protein liquid chromatography fractions were studied using a novel gelatin-anti-IgA assay that avoided nonspecific interaction between plasma IgA and immobilized IgG used as the capture antibody in antifibronectin capture assay. Using our gelatin-anti-IgA assay, we failed to demonstrate a diagnostic increase in IgA-fibronectin aggregates in polymeric IgA from patients with IgAN compared with controls. Our finding of circulating IgA-fibronectin aggregates in patients with IgAN comparable to those of healthy controls did not support the notion that these aggregates may have a pathogenetic role or diagnostic value in IgAN.

Antibodies↗
PubMed1996

Use of low-dose low molecular weight heparin in hemodialysis.

We investigated the lowest effective dosage of low molecular weight (LMW) heparin for hemodialysis in comparison to unfractionated (UF) heparin. Initial hemodialysis sessions were undertaken in 10 uremic patients with UF heparin of the dose habitually required for each patient. Four-hour hemodialysis sessions were then undertaken with LMW heparin (nadroparin) in a single bolus (200 anti-Xa unit Institut Choay/kg [aXaU IC/kg], 175 aXaU IC/kg, 150 aXaU IC/kg, or 125 aXaU IC/kg; two sessions for each dosage). Anti-Xa levels and activated partial thromboplastin time (APTT) were monitored hourly during dialysis. Fiber bundle volume of dialyzer was measured before and after dialysis. Urea clearance was determined at the onset and completion of dialysis. There were no episodes of excessive bleeding, clotting of dialyzers, or clots in air traps with UF heparin or LMW heparin. A 35% increase in APTT above baseline was observed in all dialysis sessions 1 hour after LMW heparin bolus, but the APTT decreased rapidly thereafter. The anti-Xa levels exceeded 0.5 U/mL for all sessions using LMW heparin irrespective of the dosage. No significant reduction of urea clearance was found in dialysis with either UF or LMW heparin. No reduction of fiber bundle volume of dialyzer was observed in dialysis with either UF or LMW heparin, although a small reduction (3%) was observed in dialysis with LMW heparin at 125 aXaU IC/kg. We concluded that the use of LMW heparin for hemodialysis is safe and effective as compared with UF heparin. The lowest effective dosage can be reduced to 125 aXaU IC/kg in high-risk patients to reduce hemorrhagic complications.

Adult↗
PubMed1996

Effect of an pyruvate-based peritoneal dialysis solution on the pH of a residual peritoneal dialysis fluid.

An acidic (pH 5.2) pyruvate-based peritoneal dialysis solution or an equally acidic lactate-based counterpart was added to a residual fluid (i.e., peritoneal effluent) obtained from each of 6 continuous ambulatory peritoneal dialysis patients. It was found that the residual fluids were able to raise the pH of the resultant residual fluid/peritoneal dialysis solution mixture to a higher level in the case of the pyruvate-based solution than in the case of the lactate-based one.

Ascitic Fluid↗
PubMed1996

Effects of a pH 7.4, lactate-based and a pH 7.4, bicarbonate-based peritoneal dialysis solutions on neutrophil superoxide generation.

Neutrophil superoxide formation was similar when cells were incubated in self-made, non-autoclaved pH 7.4, lactate-based peritoneal dialysis solutions or in their self-made, non-autoclaved, pH 7.4, bicarbonate-based counterparts. On the other hand, commercially available, autoclaved, pH 7.4, lactate-based peritoneal dialysis solutions resulted in inhibition of superoxide production when compared to their self-made, non-autoclaved, pH 7.4, lactate-based or bicarbonate-based counterparts. The cause for this inhibition of superoxide generation is at present unknown.

Adult↗
PubMed1995

Collection of a representative fraction of total spent hemodialysate.

We describe a method of obtaining a small representative fraction of spent dialysate by placing a side tube in the dialysate drainage tube. The side tube, capped with a small-gauge needle, is used to collect the specimen. Fractions obtained in this fashion are found to have a composition similar to that of the remaining spent dialysate.

Hemodialysis Solutions↗
PubMed1995

Effect of dialysate temperature on central hemodynamics and urea kinetics.

Use of cool dialysate is associated with increased intradialytic blood pressure, but the hemodynamic mechanism is unknown. Whether changes in dialysate temperature affect muscle blood flow, which may the alter the degree of urea compartmentalization, also is unknown. We measured hemodynamics and blood and dialysate-side urea kinetic indices in nine hemodialysis patients during two cool (35.0 degrees C) versus two warm (37.5 degrees C) dialysate treatments. The % change in mean arterial pressure was different when using the cool (+6.5 +/- 9.7 mm Hg) versus the warm (-13.4 +/- 3.6) dialysate (P < 0.01), despite comparable amounts of fluid removal. Percent changes in cardiac output were similar with the two dialysates, and thus the blood pressure effect was due primarily to changes in total peripheral resistance (% delta TPR, cool +26 +/- 13.6, warm +8.6 +/- 14.5; P < 0.02). During cool dialysate use tympanic membrane temperature changed by -0.51 +/- 0.23 degree C, whereas body temperature increased by 0.52 +/- 0.14 degree C during use of warm dialysate. Measured urea recovery normalized to the predialysis urea nitrogen concentration was similar with the two treatments: cool 31.3 +/- 0.039 liter-1; warm 29.7 +/- 0.021; P = NS. In a second study, post-dialysis urea rebound values from 15 seconds to 30 minutes, expressed as the percent of the post-dialysis SUN, were similar after the two treatments: cool 11.79 +/- 1.4; warm 12.21 +/- 2.27, P = NS.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1995

Neutrophil intracellular pH after exposure of neutrophils to a euhydric, lactate-based peritoneal dialysis solution and its euhydric, bicarbonate-based counterpart.

The effects of euhydric, lactate-based peritoneal dialysis solutions and those of their euhydric, bicarbonate-based counterparts, on neutrophil intracellular pH are comparable. This similarity in effects on intracellular acidity may have bearings on the influences of these solutions on cellular functions in general.

Adolescent↗
PubMed1994

Detection of functional and dimeric activin A in human marrow microenvironment. Implications for the modulation of erythropoiesis.

Activin A, which was initially recognized as a gonadal protein, was implicated in the modulation of erythropoiesis through a paracrine control in the bone marrow microenvironment. Present studies demonstrate that, in contrast to T lymphocytes and cultured skin fibroblasts, human marrow stromal cells produce a functional and dimeric beta A beta A molecule (i.e., activin A). RT-PCR further indicates that both alpha and beta A mRNAs of inhibin A/activin A are produced in human stromal cells. The level of beta A subunit mRNAs, however, is in large excess over that of alpha subunit mRNAs, suggesting the predominant production of beta A beta A dimers, as well as some inhibin A (alpha beta A). It should be noted, however, that the beta A subunit can form dimeric proteins other than activin A, such as activin AB (beta A beta B) and inhibin A (alpha beta A). Hence, the presence of the beta A subunit may not necessarily indicate the production of the activin A molecule in any tissue. Therefore, a special quantitative sandwich ELISA assay specific for the dimeric beta A beta A molecule was developed for the measurement of activin A. With this assay, production of activin A in marrow stromal cells is found to be greatly enhanced by cytokines and inflammatory mediators such as TNF-alpha, IL-1 alpha, and lipopolysaccharide. These studies thus suggest that inflammatory cytokines are the inducers for activin A, probably serving a role of up-regulating activin A production locally in bone marrow microenvironment. At present, activin A is not known to play any role in inflammatory reaction; this study may thus raise the possibility that activin A performs more functions than are currently recognized. Alternatively, the enhanced production of this molecule in the bone marrow microenvironment may be regarded as a compensatory mechanism in host defenses, countering inflammatory mediators that are known to suppress erythropoiesis.

Activins↗
PubMed1994

Employing L-lactic acid powder in the preparation of a dry "acid concentrate" for use in a bicarbonate-based dialysis solution-generating system: experience in hemodialysis patients.

By replacing the liquid acetic acid present in the "acid concentrate" of a bicarbonate-based dialysis solution-generating system with an equimolar amount of solid L-lactic acid and by using the dry forms of the remaining constituents, we were able to create a dry "acid concentrate" just prior to use, and successfully employed this "acid concentrate" to produce a bicarbonate-based solution to hemodialyze patients.

Bicarbonates↗