William P. Tew

Use of the coulombic interactions of the lanthanide series to identify two classes of Ca2+ binding sites in mitochondria

Abstract The degree of inhibition of respiration-dependent vs respiration-independent Ca2+ binding by rat liver mitochondria by different members of the lanthanide family was used to establish the existence of two different classes of Ca2+ binding sites. The distinction is based on the differences in cation:site interactions between the two classes of sites and the members of the lanthanide series. Lanthanide inhibition of respiration-dependent Ca2+ uptake suggests that the binding site is specific for the calcium ion. Those members of the lanthanide family whose ionic radii are nearer that of Ca2+ are the best inhibitors. The inhibition of respiration-independent Ca2+ binding is much different, indicating non-specific cation absorption.

Synovial fluid analysis and equine joint disorders

Summary In this report, we review our experience of comprehensive synovial fluid analysis in over 2500 equine cases studied over the past two years. These investigations have indicated that synovial membrane inflammation and articular degeneration are important factors in many common joint disorders and contribute significantly to joint dysfunction. Information gained through synovial fluid analysis can indicate the nature and extent of intra-articular pathologies and is a valuable adjunct to other diagnostic techniques in establishing diagnoses, selecting treatments, and developing realistic prognoses. Variations in joint fluid parameters were shown in this study to be useful in differentiating a normal joint from such disorders as traumatic effusion acute synovitis, chronic synovitis and leukocytic synovitis. The most helpful synovial fluid parameters in this study were relative viscosity, hyaluronic acid, mucin clot, protein, leukocyte count and cartilage fragments.

Influence of phosphocitrate, a potent inhibitor of hydroxyapatite crystal growth, on mineralization of cartilage and bone

Summary An in vivo bone induction system was used to study the effect of phosphocitrate, a potent inhibitor of calcium phosphate crystallization, on the initial stages of mineralization. Subcutaneous transplantation of coarse powders of demineralized rat diaphyseal bone matrix into allogenic recipients results in a well defined sequence of mineralization steps involving cartilage formation, calcification and bone formation. Phosphocitrate when administered locally or systemically had no effect on the mineralization of either cartilage or bone. Dose levels were chosen to be consistent with that of a previous study which demonstrated that ethane-1-hydroxy-1, 1-diphosphonate (EHDP), a similarly effective in vitro inhibitor of hydroxyapatite crystallization, has a strong inhibitory effect on the initial mineralization steps. Since EHDP is not metabolized in vivo , the lack of effect of phosphocitrate in this study is suggestive of possible enzymatic hydrolysis at the calcification site which may regulate the level of phosphocitrate.

A rapid extraction technique for atomic absorption determinations of kidney calcium

Abstract A simple method of extracting calcium from kidney tissue prior to atomic absorption measurements of calcium in experimental models of nephrocalcinosis is described. This technique results in substantial time savings over traditional ashing or acid-digestion techniques for monitoring the rate and extent of calcification of the kidney. Comparisons of calcium in the kidneys of mice maintained on regimens which produce both intra- and extracellular calcification by both extraction and ashing techniques produced statistically equivalent results. Brief sonication of the tissue in a butanol-HCl-lanthanum medium effectively extracted calcium allowing accurate determination of tissue calcium without ashing. This technique has proven very useful when numerous samples must be processed daily.

Inhibition of PTH-Induced Nephrocalcinosis by Phosphocitrate

Earlier studies from this Institution have suggested that phosphocitrate may play an important role in the regulation of physiological calcification1,2. It has been proposed as a constituent of normal urine and mitochondrial extracts which can prevent the transformation of amorphous calcium phosphate to crystalline phases.

Demonstration by synovial fluid analysis of the efficacy in horses of an investigational drug (L-1016)

Summary A glycosaminoglycan polysulfate ester, L-1016, was administered intra-articularly over a period of six-weeks to selected horses with joint disorders which demonstrated by synovial fluid analysis lesions and/or degeneration of the articular cartilage and impairment of synovial membrane function. Over the course of treatment, significant changes in synovial fluid viscosity and protein were observed. In general, these laboratory data were reflected directly in clinical observations. Response to the treatment was characterized by decreases in outward signs of swelling, increases in flexion and lessening of lameness.

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 patients 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.

Prevention of Phosphate Induced Progression of Experimental Uremia by 3-Phosphocitric Acid

Excess dietary phosphate produces progressive increase in calcium content of the kidney and also leads to progressive deterioration of renal function1–3. The important variables responsible for determination of both the rate of deposition of calcium and loss of renal function are the quantity of dietary phosphate, the amount of functioning renal tissue and the level of parathyroid activity3,4. Given sufficient reduction in the size of the functioning renal mass, progressive deposition of calcium can be demonstrated in the kidney of animals maintained on a diet of normal phosphate content5. The histologic changes associated with these progressive calcium deposits provide convincing evidence of the structural damage produced, apparently resulting from cellular damage associated with calcium phosphate deposition 3,6.