Health characteristics of inland waterway merchant marine captains and pilots.

BACKGROUND: Most published studies on seafarer health have focused on patterns of mortality, injury and communicable diseases. Little information is available regarding lifestyle-related cardio-metabolic disease in maritime populations. AIMS: To describe health characteristics of a population of US inland waterway merchant marine captains and pilots. METHODS: A cross-sectional study of the health characteristics of mariners required to complete the United States Coast Guard physical assessment at a regional medical centre from 2003-10. Variables collected included self-reported smoking status, body mass index, fasting lipids, glucose and triglyceride levels, blood pressure and treadmill time and maximal oxygen uptake as measured using the Bruce Protocol. Major medical conditions related to lifestyle and risk for metabolic syndrome were also assessed. RESULTS: There were 388 participants. The study population had high prevalence of obesity (61%), smoking (41%), high triglycerides (42%), low HDL cholesterol (47%), high blood pressure (42%), high fasting glucose (22%) and three or more features of the metabolic syndrome (39%). CONCLUSIONS: This population exhibited a high prevalence of chronic disease risk factors and could potentially benefit from health promotion programmes aimed at improving health and fitness.

Crystal-induced inflammation in canine joints. II. Importance of polymorphonuclear leukocytes.

In an experimental model, the polymorphonuclear leukocyte was found to be necessary to the inflammation induced by crystals. This conclusion is based on (a) the invariable migration of polymorphonuclear leukocytes into the synovial fluid of canine joints injected with urate crystals, (b) the experimental suppression of the synovitis by the depletion of polymorphonuclear leukocytes in animals treated with vinblastine, (c) the dependence of the degree of suppression on the degree of leukocyte mobilization into the joint space, and (d) the restoration of the inflammatory response in a leukopenic animal by perfusion with normal blood.

Crystal-induced inflammation in canine joints. I. An experimental model with quantification of the host response.

Injection of sodium urate or calcium pyrophosphate crystals into the stifle joints of anesthetized dogs almost invariably induced an acute exudative response. This response was quantified by serial measurements of intra-articular pressure, pH and leukocyte concentration. Pressure rose progressively and reflected intra-articular volume increase. The hydrogen ion concentration increased as the reaction progressed and correlated in a given exudate with the leukocyte concentration. Analysis of sequential physiologic and biochemical changes occurring in this model of crystal-induced inflammation may provide insight into the mechanisms of acute gouty arthritis in man.

Differential membranolytic effects of microcrystalline sodium urate and calcium pyrophosphate dihydrate.

Microcrystals of sodium urate produced direct lysis of erythrocyte membranes, as had been described previously for silica. Calcium pyrophosphate crystals induced modest erythrocyte hemolysis, also, and time-course experiments showed a markedly different reaction curve from those produced by silica and urate. Polyvinylpyridine-N-oxide, a strong hydrogen acceptor, was bound from solution to urate and silica, but not to calcium pyrophosphate crystals; this compound effectively blocked urate and silica, but not calcium pyrophosphate or control hemolysis. Dextran and heparin inhibited urate-but not silica-induced hemolysis. If erythrocyte and lysosome membranes react similarly to these particles, then the absence of phagosomes in gouty synovial fluid leukocytes, and the presence of these structures in pseudogout, may be explained.

Measurement of inorganic pyrophosphate in biological fluids. Elevated levels in some patients with osteoarthritis, pseudogout, acromegaly, and uremia.

A rapid and relatively simple method for measurement of inorganic pyrophosphate (PPi) in biological samples has been described. The mean +/-SEM of plasma samples from 94 normal subjects was 1.8+/-0.06 muM, giving a normal range (99% confidence limits) of 0.16 - 3.40 mumol/liter. Analysis of 17 plasma samples in duplicate showed a standard deviation of 0.18, giving a 99% probability that a single determination of plasma PPi would be +/-0.68 muM of the true value. The mean PPi levels in plasma from subjects with osteoarthritis, pseudogout, acromegaly, and uremia were significantly greater than the normal mean (P < 0.01). Samples from rheumatoid arthritis showed PPi levels distributed about a mean identical to the normal mean. Plasma inorganic orthophosphate levels correlated positively with PPi levels in samples from normal subjects and in samples from patients with osteoarthritis, pseudogout, and uremia, but not with acromegaly. This correlation was statistically significant only in the normal samples and in those from patients with osteoarthritis.

Identification of inorganic pyrophosphate in human platelets and its release on stimulation with thrombin.

Serum inorganic pyrophosphate (PPi) levels were consistently two- to threefold higher than plasma PPi prepared from the same blood. PPi was found in platelets in amounts ranging from 1.4 to 3 nmol/10(8) cells, using three different techniques for quantification. These levels are approximately 800 times higher than the mean PPi concentration in normal plasma and approximate the levels of ADP found in platelets by other workers. About 50% of platelet PPi was specifically released extracellularly after stimulation with thrombin. Timed release experiments showed a pattern of release that resembled that described for ADP and ATP. This pattern was clearly different from that shown by platelet calcium, serotonin, or beta-glucuronidase. Platelet inorganic pyrophosphatase was not released into the supernate in detectable amounts. Platelets from patients with nucleotide storage pool deficiency showed greatly reduced levels of PPi as compared with control. There was no detectable release of PPi into extracellular medium after thrombin addition to a suspension of these platelets.

Factors affecting the solubility of calcium pyrophosphate dihydrate crystals.

The solubility of triclinic calcium pyrophosphate dihydrate (CPPD) crystals was measured under varying conditions using 45Ca-labeled crystals, expressing solubility as micromoles per liter of 45Ca in solution. In a 0.1-M Tris-HC1 buffer pH 7.4, the solubility of accurately sized CPPD crystals (37-20mum) was 60muM with maximal solubility being attained after about 8 h incubation at 37degreeC. Reduction in crystal size, decrease in pH, increase in ionic strength, Mg++, citrate, and albumin all increased solubility. The most marked effects on solubility occurred when changing the calcium concentration or by enzymatic hydrolysis of inoganic pyrophosphate to orthophosphate. It was found that decreasing the ionized calcium level below 5 mg/100 ml resulted in a progressive enhancement of solubility. The observed solubility-enhancing effects of albumin could be explained solely on its calcium-binding ability and thereby, altered ionized calcium level. Diffusible calcium in synovial fluid was only 40% of the total calcium concentration, which means most joint fluids are normally near the critical concentration of 5 mg/100 ml of ionized calcium, below which solubility is enhanced. During surgery, especially parathyroidectomy, calcium levels fall, favoring dissolution of CPPD crystals. We speculate that the slight decrease in crystal size during dissolution frees them from their cartilaginous mold, resulting in a dose-dependent inflammatory reaction as they are "shed" into the joint space. Crystal shedding may be reinforced by the modest fall in joint fluid pH accompanying the inflammatory response.

A unique ectonucleotide pyrophosphohydrolase associated with porcine chondrocyte-derived vesicles.

Previous studies have shown increased nucleotide pyrophosphohydrolase (EC 3.6.1.8) (NTPPHase) activity in detergent extracts of degenerated human cartilage containing calcium pyrophosphate dihydrate (CPPD) crystals relative to those from osteoarthritis or normal cartilage. NTPPHase was later shown to be an ectoenzyme and its activity was increased in synovial fluid from patients with CPPD crystal deposits relative to fluids from other types of arthritis. We have purified a soluble 61-kD NTPPHase from conditioned media of organ-cultured porcine articular cartilage to electrophoretic homogeneity. Its NH2-terminal sequence through 26 cycles showed < 30% homology to any previously reported protein sequence. An antibody raised to a synthetic peptide corresponding to this sequence reacted with denatured but not native enzyme. This antibody reacted against a sedimentable vesicle-associated 127-kD protein in conditioned media from cultured articular cartilage or from chondrocytes in primary monolayer culture and against a series of soluble proteins in conditioned media supernatant, including a 61-kD protein representing our original isolate. No reactivity was found in 1% SDS extracts of washed cultured chondrocytes, although these contained greater NTPPHase activity than the conditioned media. Antibody to PC-1, another ectoNTPPHase, reacted with 1% SDS extracts of whole chondrocytes but not against those chromatographic fractions containing the major portion of NTPPHase activity. Release of the vesicle-associated 127-kD enzyme into conditioned medium was stimulated three- to sevenfold by TGF beta 1. The antibody also reacted with a series of soluble proteins and with 127-kD sedimentable protein in human synovial fluid. Kinetic studies supported the existence of a unique vesicle-associated NTPPHase; apparent Km (mM) of chondrocyte membrane NTPPHase was 1.5 and 3.0 at pH 7.3 and 9.88, respectively; apparent Km (mM) of vesicle associated NTPPHase was 0.83 and 1.28 at pH 7.3 and 9.88. The data suggest the existence of a unique ecto-NTPPHase associated with vesicles derived from normal articular cartilage.

Release of platelet constituents by monosodium urate crystals.

The release of human platelet constituents by the etiologic agent of gout, the monosodium urate crystal, is described here. In suspensions of washed platelets, response to urate crystals proceeded in two phases: A secretory phase involved the rapid active release of serotonin, ATP, and ADP with little loss of lactic dehydrogenase or beta-glucuronidase. A lytic phase involved the slower loss of all platelet constituents. Both phases were inhibited by iodoacetate plus dinitrophenol, suggesting an energy requirement. In ultrastructural studies, lysis of washed platelets which appeared to contain crystals was seen. Urate crystals were also shown to induce serotonin release and platelet lysis in citrated platelet-rich plasma. Since urate crystals are deposited at a variety of sites, urate crystal-platelet interaction in vivo is a possibility. Such interactions, leading to release of platelet constituents, might contribute to gouty inflammation or to enhanced atherogenesis.

Inorganic pyrophosphate pool size and turnover rate in arthritic joints.

Recent studies have shown elevated inorganic pyrophosphate (PPi) levels in most knee joint fluid supernates from patients with pseudogout (PG) or osteoarthritis (OA) and more modestly elevated levels in some supernates from patients with gout or rheumatoid arthritis (RA) relative to PPi levels found in the venous blood plasma of normal or arthritic subjects. We measured the intraarticular PPi pool and its rate of turnover to better understand the significance of the joint fluid-plasma PPi gradient. Preliminary studies in rabbits showed that (32-P)PPi passed from joint space to blood and vice versa without detectable hydrolysis. Incubation of natural or synthetic calcium pyrophosphate dihydrate (CPPD) microcrystals with synovial fluid in vitro in the presence of (32P)PPi tracer showed no change in PPi specific activity in the supernate over a 19-h period so that exchange of PPi in solution with that in CPPD microcrystals could be ignored. Clearance rates of (32P)PPi and of (33P)Pi, as determined by serially sampling the catheterized knee joints of volunteers with various types of arthritis over a 3-h period, were nearly identical. The (32P)PPi/(32P)Pi was determined in each sample. A mixture of a large excess of cold PPi did not influence the clearance rate of either nuclide. The quantity of PPi turned over per hous was calculated from the pool size as determined by isotope dilution and the turnover rate. The residual joint fluid nuclide was shown to be (32P)PPi. The PPi pool was generally smaller and the rate of turnover was greater in clinically inflamed joints. The mean plus or minus SEM pool size (mu-moles) and turnover rate (percent/hour) in PG knees was 0.23 plus or minus 0.07 and 117 plus or minus 11.9, hydrolysis rate (%/h) to Pi was 27.7 plus or minus 13.2; in OA knees: 0.45 plus or minus 0.26 and 72 plus or minus 9.2, hydrolysis 6.9 plus or minus 0.9; in gouty knees: 0.8 plus or minus 0.41 and 50 plus or minus 11.6, hydrolysis 9.8 plus or minus 2.8; and in RA knees: 0.14 plus or minus 0.14 and 114 plus or minus 35.8, hydrolysis 236 plus or minus 116. PPi turnover (mumoles/hour) correlated with the degree of OA change present in the joint as graded by radiologic criteria irrespective of the clinical diagnosis. Mean PPi turnover in joints with advanced OA was greater than in those with mild or moderate changes (P smaller than 0.001), but the mild and moderate groups showed no significant difference. We conclude that synovial PPi turnover and elevated PPi fluid concentrations are not specific for PG patients, and that these factors alone cannot be the only determinants of CPPD crystal deposition.

Pyrophosphohydrolase activity and inorganic pyrophosphate content of cultured human skin fibroblasts. Elevated levels in some patients with calcium pyrophosphate dihydrate deposition disease.

In calcium pyrophosphate dihydrate (CPPD) crystal deposition disease, metabolic abnormalities favoring extracellular inorganic pyrophosphate (PPi) accumulation have been suspected. Elevations of intracellular PPi in cultured skin fibroblasts from a single French kindred with familial CPPD deposition (19) and elevated nucleoside triphosphate pyrophosphohydrolase activity (NTPPPH), which generates PPi in extracts of CPPD crystal-containing cartilages (14) favor this suspicion. To determine whether NTPPPH activity or PPi content of cells might be a disease marker expressed in extraarticular cells, human skin-derived fibroblasts were obtained from control donors and patients affected with the sporadic and familial varieties of CPPD (CPPD-S and CPPD-F) deposition. Intracellular PPi was elevated in both CPPD-S (P less than 0.05) and CPPD-F (P less than 0.01) fibroblasts compared with control fibroblasts. Ecto-NTPPPH activity was elevated in CPPD-S (P less than 0.01) but not CPPD-F. Intracellular PPi correlated with ecto-NTPPPH (P less than 0.01). Elevated PPi levels in skin fibroblasts may serve as a biochemical marker for patients with familial or sporadic CPPD crystal deposition disease; ecto-NTPPPH activity further separates the sporadic and familial disease types. Expression of these biochemical abnormalities in nonarticular cells implies a generalized metabolic abnormality.

Diagnostic thresholds for diabetes: the association of retinopathy and albuminuria with glycaemia.

AIM: We examined the association of fasting plasma glucose (FPG), 2-h plasma glucose (2hPG) and HbA1c with retinopathy and microalbuminuria using both deciles of glycaemia and change point models, to validate current diagnostic criteria for diabetes and to identify therapeutic thresholds for glycaemic control. METHODS: The Australian Diabetes Obesity and Lifestyle study (AusDiab), conducted in 1999-2000, included adults aged > or =25 years from 42 randomly selected areas of Australia. Retinopathy and albuminuria were assessed in participants identified as having diabetes (based on self report and oral glucose tolerance test), impaired fasting glucose, impaired glucose tolerance and in a random sample with normal glucose tolerance. Data were available for 2,182 participants with retinal photographs and 2,389 with urinary albumin/creatinine results. RESULTS: The prevalence of retinopathy in the first 8 deciles of FPG and HbA1c and the first 9 deciles of 2hPG were 7.2, 6.6, and 6.3%, respectively and showed no variation with increasing glucose or HbA1c. Above these levels, the prevalence rose markedly to 18.6% in the top 2 deciles of FPG, 21.3% in the top 2 deciles of HbA1c and 10.9% in the top decile of 2hPG. The thresholds for increasing prevalence of retinopathy were 7.1 mmol/l for FPG, 6.1% for HbA1c and 13.1 mmol/l for 2hPG. The prevalence of microalbuminuria rose gradually across deciles of each glycaemic measure. Thresholds were less clear than for retinopathy, but were seen at a FPG of 7.2 mmol/l and HbA1c of 6.1%, with no evidence of a threshold effect for 2hPG. CONCLUSIONS: The prevalence of retinopathy rose dramatically in the highest deciles of each glycaemic measure, while for microalbuminuria the increase of prevalence was more gradual. The FPG values corresponded well with the WHO diagnostic cut-point for diabetes, however the 2hPG value did not. HbA1c thresholds were similar for both retinopathy and microalbuminuria and compared well to values shown in other studies. These results support current targets for FPG and HbA1c in preventing microvascular complications.

Polymyalgia rheumatica begins at 40.

Three cases of polymyalgia rheumatica with onset under age 50 are described. Most large series of patients with this entity contain a few examples of onset below age 50. This diagnosis should be made with confidence in younger patients with typical symptoms and laboratory findings, and showing complete suppressions of disease activity with relatively small daily doses (20 mg or less) of corticosteroids.

Milwaukee shoulder syndrome. Fifteen additional cases and a description of contributing factors.

Fifteen additional patients with Milwaukee shoulder syndrome are described, bringing our total series to 30 cases. The condition occurred predominantly in elderly women and was characterized by severe glenohumeral joint degeneration and dissolution of the fibrous rotator cuff. Synovial fluids contained few leukocytes, but were often blood tinged. Basic calcium phosphate crystal aggregates and particulate collagens were noted in nearly all fluids, and collagenase activity was detectable in some, but not all, fluids. The knee joints were involved with a similar process in about half of our patients. In contrast to primary osteoarthritis, lateral tibiofemoral compartment involvement was common. Factors that may predispose to this syndrome included deposition of calcium pyrophosphate dihydrate crystals, direct trauma or chronic joint overuse, chronic renal failure, and denervation.

Variations in site and levels of expression of chondrocyte nucleotide pyrophosphohydrolase with aging.

The aim of this study was to identify changes in cartilage intermediate layer protein/nucleotide pyrophosphohydrolase (CILP/NTPPH) expression in articular cartilage during aging. Adult (3-4 years old) and young (7-10 days old) porcine articular hyaline cartilage and fibrocartilage were studied by Northern blot analysis, in situ hybridization, and immunohistochemistry using a complementary DNA (cDNA) probe encoding porcine CILP/NTPPH and antibody to a synthetic peptide corresponding to a CILP/NTPPH sequence. Northern blot analysis of chondrocytes showed lower expression of CILP/NTPPH messenger RNA (mRNA) in young cartilage than in adult cartilage. In adult cartilage, extracellular matrix from the surface to the middeep zone was immunoreactive for CILP/NTPPH, especially in the pericellular matrix surrounding the middeep zone chondrocytes. In young cartilage, chondrocytes were moderately immunoreactive for CILP/NTPPH throughout all zones except the calcified zone. The matrix of young cartilage was negative except in the superficial zone. In young cartilage, CILP/NTPPH mRNA expression was undetectable. In adult cartilage, chondrocytes showed strong mRNA expression for CILP/NTPPH throughout middeep zones. Protein and mRNA signals were not detectable below the tidemark. CILP/NTPPH secretion into matrix around chondrocytes increases with aging. In this extracellular site it may generate inorganic pyrophosphate and contribute to age-related calcium pyrophosphate dihydrate crystal deposition disease.

Molecular cloning and expression of a porcine chondrocyte nucleotide pyrophosphohydrolase.

The porcine 127-kDa nucleotide pyrophosphohydrolase (NTPPHase) had been previously purified from the conditioned culture media of porcine articular cartilage. Protein sequencing of an internal 61-kDa proteolytic fragment of NTPPHase (61-kDa NTPPHase) determined the 26 N-terminal amino acids. This sequence was used to amplify a DNA fragment, which was used as a probe to clone the gene encoding the 61-kDa NTPPHase from a porcine chondrocyte cDNA library. DNA sequence analysis showed the cDNA insert to be 2509 bp, corresponding to a predicted open reading frame (ORF) encoding 599 amino acids. The 26 N-terminal amino acids of the 61-kDa NTPPHase were located within the ORF immediately downstream of a putative protease recognition region, RRKRR. This is consistent with this cDNA insert representing an internal proteolytic fragment of the full length 127-kDa NTPPHase. BLAST and FASTA analysis confirmed that the deduced amino acid sequence of 61-kDa NTPPHase was unique and did not possess a high degree of homology to sequence in the non-redundant protein and nucleotide databases. Proteins that possess limited homology (< 17%) with the 61-kDa NTTPPHase include several prokaryotic and eukaryotic ATP pyrophosphate-lyases (adenylate cyclase). Northern blot analysis of porcine chondrocyte RNA showed that the DNA encoding the 61-kDa NTPPHase hybridized to a single 4.0-kb RNA transcript. This DNA probe also hybridized to a single species of human chondrocyte RNA. Expression of a 61-kDa protein was detected by coupled in-vitro transcription/translation. Western blot analysis of this in-vitro transcription/translation reaction detected a 61-kDa protein, using an antibody raised against the peptide sequence that was originally used to clone the 61-kDa NTPPHase. These data indicate the successful in-vitro cloning and expression of the porcine chondrocyte 61-kDa NTPPHase. Future studies that utilize the gene encoding the 61-kDa NTPPHase may allow the characterization of the role of NTPPHase in calcium pyrophosphate dihydrate (CPPD) crystal deposition disease.

Simple method for measurement of lower extremity muscle strength.

A simple, rapid, reproducible method for quantification of lower extremity muscle strength was standardized. The time needed to stand 10 times from a standard chair was recorded in 139 healthy subjects, aged 20 to 85 years (77 men, 62 women). Reproducibility was 6.8 percent (+/- 3.4 percent). Neither height nor weight was related to time in either sex. Weight was related to time (p less than 0.05) after adjusting for age, but this effect was slight compared with the effect of age alone. A highly significant (p less than 0.0001) relationship between time and age was found in both sexes. Younger men performed better than younger women, although this difference was lost in the older age groups. The results of this simple test correlated well with published data on the strength of knee flexor and extensor muscles in groups of men and women of various ages. This method was used to evaluate serially six consecutive patients with classic polymyositis or dermatomyositis. Improvement after treatment with prednisone used alone or in combination with azathioprine or methotrexate was found in all cases.

The reflex sympathetic dystrophy syndrome. I. Clinical and histologic studies: evidence for bilaterality, response to corticosteroids and articular involvement.

Eleven consecutive patients fulfulling criteria for the reflex sympathetic dystrophy syndrome (RSDS) were studied by quantitative clinical methods, providing measurements of swelling (ring size), tenderness (dolorimeter) and functional capacity (grip strength). The predominantly affected extremity was clearly identified by these technics and its serial progress determined in six patients. Corticosteroid therapy predictably resulted in improvement of all treated patients. Greater tenderness was found in the joints than in the interjoint areas, indicating a possible accentuation of the disease process in juxta-articular tissues. Synovial biopsy specimens in four patients were abnormal, and the histology was presented in detail for the first time. All patients showed bilateral involvement during the study, providing evidence for a central neural mechanism in the RSDS.

The reflex sympathetic dystrophy syndrome. II. Roentgenographic and scintigraphic evidence of bilaterality and of periarticular accentuation.

Patchy osteoporosis is the primary roentgenologic manifestation of the reflex sympathetic dystrophy syndrome (RSDS). As recent clinical and histologic data suggested articular changes in RSDS, fine-detail roentgenograms were obtained in eight consecutive patients. Juxta-articular and soft-tissue swelling, osteoporosis and erosions of the subchondral bone were found. 99mTcO4 and 99mTc-EHDP scintigraphy showed localization of nuclide predominantly in the juxta-articular tissues. Serial roentgenographic, scintigraphic and quantitative bone densitometric measurements showed changes that reflected the clinical course of the disease.

Identification of collagen subtypes in synovial fluid sediments from arthritic patients.

Collagen fibers in synovial fluid sediment were described a decade ago. Since then, tissue-specific collagen molecules (types) have been characterized. Techniques were devised to identify the collagen types in joint fluid sediment. Collagens were found in 12 of 17 pellets prepared from fluid aspirates from 17 knee joints of patients with various forms of arthritis. Collagen types I and III and polypeptide chains A and B (basement membrane collagen) were specifically identified in four of seven fluids from patients with active systemic lupus erythematosus (SLE) and in a single fluid from a patient with severe septic arthritis. This "collagen profile" was identical to that of rheumatoid synovium. Type II collagen, characteristic of hyaline articular cartilage, was found in two of six fluids from osteoarthritic joints. The presence of sufficient collagen (about 5 micrograms) to permit typing was correlated with roentgenographic evidence of joint space narrowing; the presence of the "synovial" collagen profile was correlated with decreased joint fluid pH.