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Biomedical subjects

W P Tew

Publications and source records attributed to W P Tew.

14 recordsLinked to original sources
PubMed1985

Relative molecular weight and concentration determination of sodium hyaluronate solutions by gel-exclusion high-performance liquid chromatography.

Gel-exclusion chromatography coupled with HPLC instrumentation can be used to determine the molecular weight of highly purified sodium hyaluronate in solution. The method is very reproducible, precise, and rapid, and allows molecular weight determinations up to 2 million to be done in the presence of considerable impurities. This technique offers considerable advantages over traditional light-scattering, sedimentation equilibrium, and viscometry methods for molecular weight determinations, in that HPLC-gel exclusion is rapid and not subject to errors arising from impurities. Simultaneous with molecular weight measurements, sodium hyaluronate concentrations can be determined with a lower range of 0.1 to 0.3 mg/ml dependent upon the sensitivity of the refractive index-detecting system. Unlike the carbazole reaction, this technique is unaffected by low-molecular-weight impurities such as monosaccharides or substances with relative molecular weights less than 18,000.

Chromatography, Gel↗
PubMed1982

Prevention of phosphate-induced progression of uremia in rats by 3-phosphocitric acid.

Male Sprague-Dawley rats were rendered uremic by surgical removal of 70% of functioning renal mass. This produced a rapid threefold rise in serum creatinine to 0.87 +/- 0.067 (SEM) mg/dl at 2 weeks postoperatively which declined subsequently to a value of 0.64 +/- 0.06 (SEM) and remained stable thereafter for an additional 4 weeks in animals maintained on a diet with normal phosphate content. Increase of dietary phosphate content to 2.2% at 2 weeks after surgery produced a significant and progressive increase in serum creatinine to values fourfold higher than the mean values in comparable partially nephrectomized control animals maintained on a diet with normal phosphate content (P less than 0.001). This deterioration in renal function was associated with extensive nephrocalcinosis, tubular dilatation, cellular necrosis, and marked interstitial inflammation. 3-phosphocitric acid, a compound which has been shown to prevent calcium phosphate crystal growth as well as to prevent in vivo nephrocalcinosis, was very effective in preventing this phosphate-induced deterioration of renal function and in preventing any significant increase in renal calcium content in animals fed a high phosphate diet. This compound was also effective in preventing the renal histologic changes associated with phosphate-induced uremia.

Animals↗
PubMed1982

Cartilaginous debris in the injured human knee. Correlation with arthroscopic findings.

Cytologic analysis of filtered synovial lavage was compared with the independent arthroscopic findings in 70 patients with knee pain secondary to injury. Correlation existed between the arthroscopic evaluation of the articular surfaces and the presence of cartilaginous fragments and their microscopic features. Study of the filtered lavage was carried out without knowledge of the patient's clinical status or arthroscopic findings. Patients with unblemished articular surfaces and normal menisci demonstrated essentially no fragments in the synovial lavage. Minimal fibrillation of the articular surface with normal menisci was associated with few cartilage fragments per sample. Patients with moderate to severe fibrillation of the articular surface requiring a surface altering procedure, demonstrated significantly more fragments per sample. Chondrocyte nuclei were visible in these fragments, often arranged in multicellular clusters. Isolated lesions of the meniscus were associated with cartilage fragments that did not contain chondrocyte nuclei. Microscopic analysis of synovial lavage may serve as a useful diagnostic adjunct in the evaluation of the painful knee and the study of the pathogenic role of cartilage fragments is osteoarthrosis.

Adolescent↗
PubMed1981

Identification of cartilage wear fragments in synovial fluid from equine joints.

Synovial fluids from 72 equine joints were examined for the presence of cartilage debris, and these findings were compared to findings from visual inspection of the articular cartilage surfaces at necropsy. Synovial fluids from 25 joints with visual cartilage damage contained one or more large particles of articular cartilage. Cartilage fragments were not found in synovial fluids from 42 of the 47 apparently normal joints; thus, a correlation may exist between cartilage debris in the synovial fluid and lesions of the articular surfaces.

Animals↗
PubMed1981

Phosphocitrate inhibits mitochondrial and cytosolic accumulation of calcium in kidney cells in vivo.

Synthetic 3-phosphocitrate, an extremely potent inhibitor of calcium phosphate crystallization as determined in a nonbiological physical-chemical assay, has many similarities to a mitochondrial factor that inhibits crystallization of nondiffracting amorphous calcium phosphate. In order to determine whether phosphocitrate can prevent uptake and crystallization of calcium phosphate in mitochondria in vivo, it was administered intraperitoneally to animals given large daily doses of calcium gluconate or parathyroid hormone, a regimen that causes massive accumulation and crystallization of calcium phosphate in the mitochondria and cytosol of renal tubule cells in vivo. Administration of phosphocitrate greatly reduced the net uptake of Ca2+ by the kidneys and prevented the appearance of apatite-like crystalline structures within the mitochondrial matrix and cytosol of renal tubule cells. Phosphocitrate, which is a poor chelator of Ca2+, did not reduce the hypercalcemia induced by either agent. These in vivo observations therefore indicate that phosphocitrate acts primarily at the cellular level to prevent the extensive accumulation of calcium phosphate in kidney cells by inhibiting the mitochondrial accumulation or crystallization of calcium phosphate.

Animals↗
PubMed1980

Synthesis and characterization of phosphocitric acid, a potent inhibitor of hydroxylapatite crystal growth.

Human urine and extracts of rat liver mitochondria contain apparently identical agents capable of inhibiting the precipitation or crystallization of calcium phosphate. Its general properties, as well as 1H NMR and mass spectra, have suggested that the agent is phosphocitric acid. This paper reports the synthesis of phosphocitric acid via the phosphorylation of triethyl citrate with o-phenylene phosphochloridate, hydrogenolysis of the product to yield triethyl phosphocitrate, hydrolytic removal of the blocking ethyl groups and also chromatographic purification. An enzymatic assay of phosphocitrate is described. Synthetic phosphocitrate was found to be an exceedingly potent inhibitor of the growth of hydroxylapatite seed crystals in a medium supersaturated with respect to Ca2+ and phosphate. Comparative assays showed phosphocitrate to be much more potent than the most active precipitation-crystallization inhibitors previously reported, which include pyrophosphate and ATP. 14C-Labeled phosphocitrate was bound very tightly to hydroxylapatite crystals. Such binding appeared to be essential for its inhibitory activity on crystal growth. Citrate added before but not after, phosphocitrate greatly enhanced the inhibitory potency of the latter. This enhancement effect was not given by other tricarboxylic acids. The monoethyl ester of phosphocitrate had no inhibitory effect on hydroxylapatite crystal growth.

Calcium Phosphates↗
PubMedDate not supplied

Synovial fluid analysis by ferrography.

Ferrography is a technique for magnetically harvesting and separating metallic particles from aqueous and non-aqueous suspensions. We have adapted this method of analysis to the study of cartilaginous and osseous wear particles, as well as fragments of soft tissue, found in the synovial fluid of human joints. As ferrography employes magnetism to harvest particles and arrange them in an orderly fashion, it is first necessary to impart a positive magnetic susceptibility to the biological materials. The trivalent paramagnetic cation of the rare earth element erbium is used for this purpose. Based on this principle, a method for the ferrographic analysis of synovial fluid has been devised, which is presently being employed in the study of human joint disease. Using this technique, improved diagnosis of arthritis may be possible. In addition, it may lead to a deeper understanding of the aetiology and pathogenesis of degenerative arthritis and other destructive joint diseases.

Arthritis↗