In situ analysis of protein chromatography and column efficiency using magnetic resonance imaging.

Magnetic resonance imaging has been used to visualize size-based protein separations inside operating chromatography columns. The effects of flow nonuniformity have been observed and analyzed quantitatively through concentration profiles of tracers measured inside the column. Analysis of these profiles provides local and averaged intracolumn plate height values for characterization of dispersion and flow nonuniformity. The magnetic resonance measurements compare favorably with conventional chromatographic measurements of column efficiency and provide more detailed insights into nonideal column performance.

Changes in proteoglycan and collagen in cartilage in rheumatoid arthritis.

Articular cartilage from thirteen patients with rheumatoid arthritis was studied by both light and electron microscopy using recently developed staining techniques for proteoglycan. Normally proteoglycan is concentrated about active chondrocytes, but in the cartilage from these patients it was found to be diminished about most of the chondrocytes while it was increased around a few. Fragmentation of collagen and phagocytosis of the fragments by chondrocytes were also noted. This dissolution of collagen was associated with loss of proteoglycan in the matrix. These findings are consistent with the variable nature of the rheumatoid destructive process and appear to be morphological reflections of biochemical changes which formerly were thought to occur in this disease only at the cartilage-pannus junction.

Classification of degenerative arthritis.

It is suggested that the former division of degenerative arthritis into idiopathic types and those secondary to some disease process is no longer valid. Recent studies have indicated that abnormal concentrations of force on cartilage lead to the development of this disease. A classification is presented that is based on the assumption that the process is initiated by abnormal concentrations of force on normal cartilage matrix, normal concentrations of force on abnormal cartilage matrix or normal concentrations of force on normal cartilage matrix that is supported by bone of abnormal consistency.

Electron microscopic evaluation of the occurrence of matrix vesicles in cartilage.

Troubled by variations in the descriptions of shape, appearance, and content of matrix vesicles and the conflicting reports of increased numbers of vesicles in the mineralizing regions of the growth plate contrasted with larger numbers in the resting zone, we embarked on a review of matrix vesicles in the growth plate using a comparison of different fixation techniques. We found matrix vesicles resembling cell debris at all levels of the growth plate, with no particular association with mineral. Lipid bodies surrounded by a membrane of proteoglycan have also been seen in large numbers. The cell debris-like matrix vesicles have been the common finding in reports of digested centrifuged cartilage and may represent cytoplasmic processes. Lipid bodies surrounded by proteoglycan may be similar to the membrane-bound vesicle described by Ali (Fed. Proc., 35:135-142, 1987) and by Bonucci (Clin. Orthod., 78:108-133, 1971).

Colloidal chromic phosphate 32P synovectomy in antigen-induced arthritis in the rabbit.

Radioisotopes have been employed in the therapy of chronic arthritis, in particular, rheumatoid arthritis for many years. A variety of isotopes have been popularized, and in the last ten years a colloidal solution of radioactive chromic phosphate 32P has been in use apparently with equivalent efficacy to others such as 169erbium, 90yttrium, and 165dysprosium. No controlled studies on this modality have been reported and few animal studies were found. The efficacy of therapeutic doses of 32P as a medical synovectomy and its effect on rabbit joints with antigen-induced arthritis were observed in 62 arthritic knee joints in 31 adult rabbits treated on one side with 0.1 microCi of 32P, the opposite serving as control. The animals were observed over a period of 11 months and examined by histologic and biochemical means. The synovium showed no evidence of radiation necrosis in treated joints. Cartilage of treated and control joints showed similar changes consistent with chronic arthritis, persistent synovitis, progressive chondrocyte degeneration, and decreased matrix metachromasia. The radiosynovectomy had neither removed synovium nor protected the cartilage. Its efficacy in humans is therefore questionable.

Potassium-induced changes in muscle free amino acid concentrations in chicks.

Two experiments with purified crystalline amino acid diets were conducted to determine the effect of dietary potassium level on chick breast muscle free amino acid concentrations. In both experiments, concentrations of muscle free glutamine, lysine and arginine increased as dietary potassium increased from 0.12 to 0.18% and decreased as dietary potassium exceeded 0.18%. As dietary potassium increased, muscle potassium concentration increased linearly with an equivalent linear decrease in muscle sodium concentration. Peak concentration of muscle free glutamine, lysine and arginine occurred in muscle with a K+:Na+ ratio of approximately 1:4. Concentrations of the three amino acids were less in muscle with K4:Na+ ratios either less than or greater than 1.4. Breast muscle concentrations of free histidine decreased slightly, while muscle free carnosine increased substantially when dietary potassium exceeded 0.18%.

Motion of the patella during walking: a video digital-fluoroscopic study in healthy volunteers.

OBJECTIVE: The alignment of the quadriceps muscle and patella suggests that the patella should deviate laterally out of the patellar groove as the quadriceps muscle contracts during walking. The surgical treatment of patellar subluxation has been based on this presumption. The purpose of this study was to determine the movements of the patella in relation to the other bones of the knee joint during normal walking. This is the first study we know of that uses radiographs to show these movements. SUBJECTS AND METHODS: Eight healthy adult volunteers with no previous complaints referable to the knee walked on a slowly moving treadmill while their patellae were imaged fluoroscopically in the anteroposterior plane with a Toshiba C-arm. Images were retrieved, transferred to radiographic film, and randomized to prevent the observers from knowing the order of images. The position of the patella was measured and plotted in relation to fixed points of the knee. RESULTS: In each of the subjects at every gait cycle, the patella was observed to move vertically first, followed by a sudden shift to the medial side before returning to its original position. CONCLUSION: Contrary to conventional understanding, our results show that the patella deviates medially rather than laterally during walking. This occurs because of differential contraction of the components of the quadriceps muscle during walking. The management of painful and subluxated patellae must be reevaluated in light of this finding.