scispace - formally typeset
Search or ask a question
Author

Leon Sokoloff

Bio: Leon Sokoloff is an academic researcher from Stony Brook University. The author has contributed to research in topics: Chondrocyte & Fetal bovine serum. The author has an hindex of 21, co-authored 41 publications receiving 6761 citations.

Papers
More filters
Journal ArticleDOI
TL;DR: Variables from the medical history, physical examination, laboratory tests, and radiographs were used to develop sets of criteria that serve different investigative purposes and these proposed criteria utilize classification trees, or algorithms.
Abstract: For the purposes of classification, it should be specified whether osteoarthritis (OA) of the knee is of unknown origin (idiopathic, primary) or is related to a known medical condition or event (secondary). Clinical criteria for the classification of idiopathic OA of the knee were developed through a multicenter study group. Comparison diagnoses included rheumatoid arthritis and other painful conditions of the knee, exclusive of referred or para-articular pain. Variables from the medical history, physical examination, laboratory tests, and radiographs were used to develop sets of criteria that serve different investigative purposes. In contrast to prior criteria, these proposed criteria utilize classification trees, or algorithms.

6,160 citations

Journal ArticleDOI
TL;DR: The data provide evidence that hyaluronate and PSLF act synergistically in the boundary lubricating activity of animal joints.
Abstract: Although hyaluronate is not a boundary lubricant in cartilaginous and latex:glass bearings, a distinct interaction with purified synovial lubricating factor (PSLF) was demonstrated by three means: 1) enhancement of lubricating ability in an artificial test system; 2) viscometry; 3) electron microscopy. The interaction was of a physical rather than a specific chemical type; it varied with the degree of purification of PSLF and of hyaluronate. The interaction accounts for retention of the relatively small PSLF molecule (∼280 kDa) with the synovial mucin on a 0.22 μm filter. The data provide evidence that hyaluronate and PSLF act synergistically in the boundary lubricating activity of animal joints.

86 citations

Journal ArticleDOI
TL;DR: When articular chondrocytes from rabbits 2 to 3 months old were transferred from confluent monolayer to spinner culture, they ceased to proliferate but deposited large quantities of metachromatic extracellular material, leading to marked depression of sulfated glycosaminoglycan (GAG) synthesis.
Abstract: When articular chondrocytes from rabbits 2 to 3 months old were transferred from confluent monolayer to spinner culture, they ceased to proliferate but deposited large quantities of metachromatic extracellular material Return of the suspended cells to monolayer conditions resulted in renewal of DNA and marked depression of sulfated glycosaminoglycan (GAG) synthesis The GAG of rabbit articular cartilage were heterogeneous and included 49% hyaluronate, 116% unsulfated chondroitin, 187%, disulfated chondroitin and 24% dermatan sulfate in addition to chondroitin sulfates 4 and 6 Monolayer cultured chondrocytes produced higher levels of sulfated GAG but much smaller quantities of hyaluronate than did dermal fibrocytes The GAG synthesized by chondrocytes in spinner culture closely resembled those of whole cartilage or synthesized by whole cartilage in organ culture

84 citations

Journal ArticleDOI
TL;DR: No significant stimulatory effect was shown by transferrin, thrombin, L-glutamine, putrescine, selenous acid, dexamethasone, 7S nerve growth factor, or multiplication-stimulating activity.
Abstract: The ability of purified growth factors, insulin, ascorbate, and several other compounds to stimulate DNA synthesis by rabbit articular chondrocytes was studied in monolayer culture. Platelet-derived growth factor (1 U/ml), pituitary fibroblast growth factor (1-100 ng/ml), and epidermal growth factor (1-50 ng/ml) were stimulatory in a basal medium supplemented with 1% heat-inactivated fetal bovine serum. Insulin, 1-50 micrograms/ml, has small growth-promoting effects but acted synergistically with platelet-derived, pituitary fibroblast, and epidermal growth factors. Increasing concentrations of serum up to 10% enhanced the growth-promoting action of the purified factors, but not of insulin. There were indications of cooperation between insulin and bovine serum albumin and dexamethasone. Ascorbate (0.2 mM) reduced or had little growth-promoting action in the basal medium. At 5 and 10% serum concentrations, however, ascorbate promoted DNA synthesis as effectively as the purified growth factors. No significant stimulatory effect was shown by transferrin, thrombin, L-glutamine, putrescine, selenous acid, dexamethasone, 7S nerve growth factor, or multiplication-stimulating activity.

81 citations

Journal ArticleDOI
TL;DR: The content of serum and its several peptide and hormonal components thus have divergent effects on growth and proteoglycan synthesis in cell culture, and this phenomenon must be taken into account in studying biochemical processes and pharmacologic reactions of articular chondrocytes in vitro.
Abstract: The effect of 3 purified peptide growth factors--platelet-derived growth factor (PDGF), epidermal growth factor (EGF), pituitary fibroblast growth factor (FGF)--heat-inactivated fetal bovine serum (FBS), insulin, and 0.2 mM ascorbate on synthesis of sulfated proteoglycan by rabbit articular chondrocytes was studied in monolayer culture. Growth of the cells increased linearly as the concentration of heat-inactivated FBS rose from 0 to 30%. Glycosaminoglycan (GAG) synthesis (35SO4/micrograms DNA) was enhanced as the concentration of heat-inactivated FBS went from 0 to 5%. At higher levels of serum, radiosulfate incorporation declined progressively. Two modes of study of the test factors were used: 1) the dose of the factor was increased while the serum concentration was fixed at a low basal level (1% heat-inactivated FBS); 2) the dose of the test factor was kept constant but the level of heat-inactivated FBS varied from 0 to 10%. There was an inverse relationship between GAG and DNA synthesis when proliferation of cells was increased by EGF and platelet lysate. PDGF (1 U/ml) stimulated radiosulfate incorporation as well as DNA formation in the serum-free medium; the values for GAG synthesis did not increase as the serum concentration increased, but the cell mass did. The action of FGF was intermediate between that of EGF and PDGF: with 50 ng FGF/ml, increasing concentrations of serum caused a large progressive reduction of radiosulfate incorporation as growth was stimulated. In basal medium, however, FGF caused mild enhancement of GAG synthesis. Insulin increased aggregatable proteoglycan production far out of proportion to its growth-promoting activity in the presence of 1% heat-inactivated FBS. The response was effaced when higher concentrations of serum were employed. Ascorbate had a unique anabolic effect, increasing both cell growth and proteoglycan synthesis that is not suppressed by higher concentrations of serum. The content of serum and its several peptide and hormonal components thus have divergent effects on growth and proteoglycan synthesis in cell culture. This phenomenon must be taken into account in studying biochemical processes and pharmacologic reactions of articular chondrocytes in vitro.

69 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: The revised criteria for the classification of rheumatoid arthritis (RA) were formulated from a computerized analysis of 262 contemporary, consecutively studied patients with RA and 262 control subjects with rheumatic diseases other than RA (non-RA).
Abstract: The revised criteria for the classification of rheumatoid arthritis (RA) were formulated from a computerized analysis of 262 contemporary, consecutively studied patients with RA and 262 control subjects with rheumatic diseases other than RA (non-RA). The new criteria are as follows: 1) morning stiffness in and around joints lasting at least 1 hour before maximal improvement; 2) soft tissue swelling (arthritis) of 3 or more joint areas observed by a physician; 3) swelling (arthritis) of the proximal interphalangeal, metacarpophalangeal, or wrist joints; 4) symmetric swelling (arthritis); 5) rheumatoid nodules; 6) the presence of rheumatoid factor; and 7) radiographic erosions and/or periarticular osteopenia in hand and/or wrist joints. Criteria 1 through 4 must have been present for at least 6 weeks. Rheumatoid arthritis is defined by the presence of 4 or more criteria, and no further qualifications (classic, definite, or probable) or list of exclusions are required. In addition, a "classification tree" schema is presented which performs equally as well as the traditional (4 of 7) format. The new criteria demonstrated 91-94% sensitivity and 89% specificity for RA when compared with non-RA rheumatic disease control subjects.

19,409 citations

Journal ArticleDOI
TL;DR: The burden of four major musculoskeletal conditions: osteoarthritis, rheumatoid arthritis, osteoporosis, and low back pain, which affects nearly everyone at some point in time and about 4-33% of the population at any given point is described.
Abstract: Musculoskeletal conditions are a major burden on individuals, health systems, and social care systems, with indirect costs being predominant. This burden has been recognized by the United Nations and WHO, by endorsing the Bone and Joint Decade 2000-2010. This paper describes the burden of four major musculoskeletal conditions: osteoarthritis, rheumatoid arthritis, osteoporosis, and low back pain. Osteoarthritis, which is characterized by loss of joint cartilage that leads to pain and loss of function primarily in the knees and hips, affects 9.6% of men and 18% of women aged > 60 years. Increases in life expectancy and ageing populations are expected to make osteoarthritis the fourth leading cause of disability by the year 2020. Joint replacement surgery, where available, provides effective relief. Rheumatoid arthritis is an inflammatory condition that usually affects multiple joints. It affects 0.3-1.0% of the general population and is more prevalent among women and in developed countries. Persistent inflammation leads to joint destruction, but the disease can be controlled with drugs. The incidence may be on the decline, but the increase in the number of older people in some regions makes it difficult to estimate future prevalence. Osteoporosis, which is characterized by low bone mass and microarchitectural deterioration, is a major risk factor for fractures of the hip, vertebrae, and distal forearm. Hip fracture is the most detrimental fracture, being associated with 20% mortality and 50% permanent loss in function. Low back pain is the most prevalent of musculoskeletal conditions; it affects nearly everyone at some point in time and about 4-33% of the population at any given point. Cultural factors greatly influence the prevalence and prognosis of low back pain.

3,361 citations

Journal ArticleDOI
TL;DR: Given the limitations of the data on which they are based, this report provides the best available prevalence estimates for arthritis and other rheumatic conditions overall, and for selected musculoskeletal disorders, in the US population.
Abstract: Objective To provide a single source for the best available estimates of the national prevalence of arthritis in general and of selected musculoskeletal disorders (osteoarthritis, rheumatoid arthritis, juvenile rheumatoid arthritis, the spondylarthropathies, systemic lupus erythematosus, scleroderma, polymyalgia rheumatica/giant cell arteritis, gout, fibromyalgia, and low back pain). Methods The National Arthritis Data Workgroup reviewed data from available surveys, such as the National Health and Nutrition Examination Survey series. For overall national estimates, we used surveys based on representative samples. Because data based on national population samples are unavailable for most specific musculoskeletal conditions, we derived data from various smaller survey samples from defined populations. Prevalence estimates from these surveys were linked to 1990 US Bureau of the Census population data to calculate national estimates. We also estimated the expected frequency of arthritis in the year 2020. Results Current national estimates are provided, with important caveats regarding their interpretation, for self-reported arthritis and selected conditions. An estimated 15% (40 million) of Americans had some form or arthritis in 1995. By the year 2020, an estimated 18.2% (59.4 million) will be affected. Conclusion Given the limitations of the data on which they are based, this report provides the best available prevalence estimates for arthritis and other rheumatic conditions overall, and for selected musculoskeletal disorders, in the US population.

2,667 citations

Journal ArticleDOI
TL;DR: Clinical criteria for the classification of symptomatic idiopathic (primary) osteoarthritis of the hands were developed from data collected in a multicenter study and required that at least 3 of these 4 criteria be present to classify a patient as having OA of the hand.
Abstract: Clinical criteria for the classification of patients with hip pain associated with osteoarthritis (OA) were developed through a multicenter study. Data from 201 patients who had experienced hip pain for most days of the prior month were analyzed. The comparison group of patients had other causes of hip pain, such as rheumatoid arthritis or spondylarthropathy. Variables from the medical history, physical examination, laboratory tests, and radiographs were used to develop different sets of criteria to serve different investigative purposes. Multivariate methods included the traditional "number of criteria present" format and "classification tree" techniques. Clinical criteria: A classification tree was developed, without radiographs, for clinical and laboratory criteria or for clinical criteria alone. A patient was classified as having hip OA if pain was present in combination with either 1) hip internal rotation greater than or equal to 15 degrees, pain present on internal rotation of the hip, morning stiffness of the hip for less than or equal to 60 minutes, and age greater than 50 years, or 2) hip internal rotation less than 15 degrees and an erythrocyte sedimentation rate (ESR) less than or equal to 45 mm/hour; if no ESR was obtained, hip flexion less than or equal to 115 degrees was substituted (sensitivity 86%; specificity 75%). Clinical plus radiographic criteria: The traditional format combined pain with at least 2 of the following 3 criteria: osteophytes (femoral or acetabular), joint space narrowing (superior, axial, and/or medial), and ESR less than 20 mm/hour (sensitivity 89%; specificity 91%). The radiographic presence of osteophytes best separated OA patients and controls by the classification tree method (sensitivity 89%; specificity 91%). The "number of criteria present" format yielded criteria and levels of sensitivity and specificity similar to those of the classification tree for the combined clinical and radiographic criteria set. For the clinical criteria set, the classification tree provided much greater specificity. The value of the radiographic presence of an osteophyte in separating patients with OA of the hip from those with hip pain of other causes is emphasized.

2,447 citations

Journal ArticleDOI
01 Aug 1982-Cell
TL;DR: Using SDS-polyacrylamide gel electrophoresis of intact collagen chains and two-dimensional cyanogen bromide peptide mapping, this work demonstrated a complete return to the differentiated collagen phenotype and demonstrates a reversible system for the study of gene expression.

2,296 citations