PubMed Health⌕ Search

Biomedical subjects

J Degroot

Publications and source records attributed to J Degroot.

11 recordsLinked to original sources
PubMed2006

Urinary pentosidine does not predict cartilage loss among subjects with symptomatic knee OA: the BOKS Study.

OBJECTIVE: Age-related changes in articular cartilage are likely to play a role in the etiology of osteoarthritis (OA). One of the major changes in the extracellular matrix of cartilage is the age-related accumulation of advanced glycation end products (AGEs). Pentosidine, an AGE crosslink, is one of the few characterized AGEs and is considered an adequate marker for the many AGEs that are formed in vivo. We used data from a longitudinal observation study to determine if urinary pentosidine could serve as a marker to predict cartilage loss. METHODS: We conducted a prospective analysis of data from the Boston Osteoarthritis of the Knee Study (BOKS); a completed natural history study of knee OA. All subjects in the study met American College of Rheumatology (ACR) criteria for knee OA. Knee magnetic resonance (MR) images were scored for cartilage in 14 plates of the knee using the Whole Organ Magnetic Resonance Imaging Score (WORMS) semiquantitative grading scheme. Within the BOKS population, a nested sample of 127 subjects (39% of the whole sample) who had both baseline pentosidine and longitudinal magnetic resonance imaging (MRI) measurements (MRIs performed at baseline and 30 months later) was assessed. Urinary pentosidine was assayed and normalized to creatinine to account for differences in urine concentrations. We analyzed the data using three different methods to assess if baseline measures of pentosidine predicted subsequent cartilage loss on MRI. These were (1) analysis 1: logistic regression with the outcome cartilage loss in any plate; (2) analysis 2: proportional odds model where the outcome was defined as 0=no cartilage loss, 1=cartilage loss in one plate, 2=cartilage loss in two plates, and 3=cartilage loss in at least three plates; and (3) analysis 3: Poisson regression with the outcome the number of plates with cartilage loss. All analyses were adjusted for age, sex and Body Mass Index (BMI). RESULTS: At baseline the mean (standard deviation) age was 67 (9) years and 54% were male. The results for the three analytic steps are as follows: Analysis 1: the odds ratio for cartilage loss is 1.01 (95% confidence interval (CI) 0.93-1.09) with 1 unit increase in pentosidine. Analysis 2: the odds ratio for more cartilage loss is 0.99 (95% CI 0.92-1.06) with 1 unit increase in pentosidine. Analysis 3: the relative number of plates with cartilage loss decreased was 1.00 (95% CI 0.95-1.03) with a 1 unit increase in pentosidine. CONCLUSION: Urinary pentosidine does not predict knee cartilage loss. Previous studies have suggested that local content within cartilage of AGEs is elevated in persons at high risk for progression. Our data suggest that these changes are not measurable systemically. Alternatively, urinary pentosidine levels reflect cartilage degradation in all joints (thus whole body cartilage breakdown) and may therefore not relate to OA severity in a single knee joint.

Aged↗
PubMed2005

Glucosamine decreases expression of anabolic and catabolic genes in human osteoarthritic cartilage explants.

OBJECTIVE: To investigate the effect of glucosamine (GlcN) in a human osteoarthritic explant model on expression of genes involved in anabolic and catabolic activities of chondrocytes. METHODS: Human osteoarthritic explants, obtained during knee arthroplasty surgery, were pre-cultured (3 days) and treated with glucosamine-hydrochloride (GlcN-HCl) or glucosamine-3-sulphate (GlcN-S) at 0.5mM and 5mM (4 days). RNA was isolated from the explants and real time RT-PCR was performed. Additionally, total matrix metalloproteinase (MMP) activity was measured in culture medium. RESULTS: Addition of 5mM GlcN led to significant down-regulation of aggrecan (2.65-7.73-fold) and collagen type II (7.75-22.17-fold) gene expression, indicating inhibited anabolic activity. Considering catabolic activities, 5mM GlcN significantly down-regulated aggrecanase-1 and MMP3 and 5mM GlcN-S additionally down-regulated aggrecanase-2 and tissue inhibitor of MMP gene expression significantly. Gene expression was not significantly altered by 0.5mM GlcN. Total MMP activity in culture medium was only significantly reduced after addition of 5mM GlcN-HCl. CONCLUSION: The effects of GlcN on gene expression in a human osteoarthritic explant model suggest that enzymatic breakdown of the extra-cellular matrix might be reduced by the addition of 5mM GlcN. Additionally, restoration of already damaged cartilage is not to be expected, because gene expression of anabolic genes is also down-regulated. We suggest that chondroprotective properties of GlcN in vivo may be based on inhibiting further degradation due to catabolic activities, rather than on the ability to rebuild cartilage.

Aged↗
PubMed2005

Urinary CTX-II levels are associated with radiographic subtypes of osteoarthritis in hip, knee, hand, and facet joints in subject with familial osteoarthritis at multiple sites: the GARP study.

OBJECTIVE: To assess the relation between the urinary concentrations of type II collagen C-telopeptide (UCTX-II) and radiographic signs of osteoarthritis (ROA) in the GARP (Genetics, Arthrosis and Progression) study. METHODS: UCTX-II levels were measured in GARP study participants, who are sibling pairs predominantly with symptomatic osteoarthritis at multiple sites. Kellgren and Lawrence scores were used to assess ROA in the knees, hips, hands, and vertebral facet joints, and spinal disc degeneration. A proportionate score was made for each joint location, based on the number of joints with ROA. The sum total ROA score represents a measure of cartilage abnormalities within each patient. By using linear mixed models the total ROA score and the joint site specific ROA scores were correlated with the UCTX-II level. RESULTS: In 302 subjects the mean (SD) and median (range) for UCTX-II were 265 (168) and 219 (1346) ng/mmol creatine, respectively. There was a significant association between the total ROA score and UCTX-II levels. Subsequent multivariate analysis showed that the joint site specific ROA score at all joint sites, except for spinal disc degeneration, contributed independently to this association. CONCLUSIONS: The total ROA score of GARP patients, representing cartilage abnormalities at the most prevalent ROA joint locations, showed an excellent correlation with UCTX-II levels. The specific ROA scores at the hip, hand, facet, and knee joints additively and independently explained this association. Even in patients with osteoarthritis at multiple sites, UCTX-II may be a sensitive quantitative marker of ROA.

Adult↗
PubMed2005

Urinary excretion of collagen degradation markers by sows during postpartum uterine involution.

Incomplete uterine involution is the putative cause of the increased embryo mortality and reproductive failure often exhibited by sows that lactate for less than 21 days. Since such short lactation lengths are common in American swine production, an effective technique to monitor the postpartum involution process and test this hypothesis might be valuable. Rapid and extensive catabolism of uterine collagen is essential for normal postpartum involution. The objective of this study was to characterize postpartum excretion of two biochemical markers of collagen degradation. In experiment I, urine samples were collected from five sows every other day from the day before parturition (day -1), through a 21-day lactation, to day 8 postweaning. The collagen crosslinks hydroxylysyl pyridinoline (HP), which is present in many tissues, and lysyl pyridinoline (LP), which is primarily concentrated in bone, were assayed by both ELISA and HPLC. Urinary levels of both free (ELISA) and total (HPLC) HP and LP increased (P < 0.001) approximately two-fold during lactation. The mean molar ratio of total HP:LP increased (P < 0.001) from 6.6 +/- 1.6 at day 1 to a maximum of 10.2 +/- 1.5 at day 7 postpartum and averaged 9.1 +/- 0.3 for the entire sampling period. These data are consistent with a postpartum increase of soft tissue collagen catabolism since bone has a low HP:LP ratio of 4 and soft tissues like the uterus have a high HP:LP ratio of >/=20 because they contain only trace amounts of LP. Since HPLC (total) and ELISA (free) crosslinks estimates were highly correlated (r = 0.85-0.91, P < 0.001) in experiment I, only the less technical ELISA technique was used in experiment II. Urine samples were collected from 21 sows every third day from day 1 to 19 of lactation. Sows from this second group exhibited one of four distinct crosslinks excretion patterns: peak on day 1 (n = 3), peak on day 7 (n = 4), peak on day 10, 13 or 16 (n = 7), or no peak (n = 7). This variation of postpartum crosslinks excretion among sows was not related to parity, body weight, lactation body weight change, litter size, or litter birth weight. Overall, data from experiments I and II indicate that urinary HP does increase postpartum in a pattern temporally consistent with uterine involution. However, significant variation among sows in the magnitude and timing of peak HP excretion was evident.

Amino Acids↗
PubMed2005

Study of cartilage and bone layers of the bearing surface of the equine metacarpophalangeal joint relative to different timescales of maturation.

REASONS FOR PERFORMING STUDY: A detailed and comprehensive insight into the normal maturation process of the different tissues that make up functional units of the locomotor system such as joints is necessary to understand the influence of early training on musculoskeletal tissues. OBJECTIVES: To study simultaneously the maturation process in the entire composite structure that makes up the bearing surface of a joint (cartilage, subchondral and trabecular bone) in terms of biochemical changes in the tissues of juvenile horses at 2 differently loaded sites of the metacarpophalangeal joint, compared to a group of mature horses. HYPOTHESIS: In all the structures described above developmental changes may follow a different timescale. METHODS: Age-related changes in biochemical characteristics of the collagen part of the extracellular matrix (hydroxylysine, hydroxyproline, hydroxypyridinum crosslinks) of articular cartilage and of the underlying subchondral and trabecular bone were determined in a group of juvenile horses (n = 13) (Group 1, age 6 months-4 years) and compared to a group of mature horses (n = 30) (Group 2, >4 years). In both bony layers, bone mineral density, ash content and levels of individual minerals were determined. RESULTS: In cartilage, subchondral bone and trabecular bone, virtually all collagen parameters in juvenile horses were already at a similar (stable) level as in mature horses. In both bony layers, bone mineral density, ash- and calcium content were also stable in the mature horses, but continued to increase in the juvenile group. For magnesium there was a decrease in the juvenile animals, followed by a steady state in the mature horses. CONCLUSIONS: In horses age 6 months-4 years, the collagen network of all 3 layers within the joint has already attained a mature biochemical composition, but the mineral composition of both subchondral and trabecular bone continues to develop until approximately age 4 years. POTENTIAL RELEVANCE: The disparity in maturation of the various extracellular matrix components of a joint can be assumed to have consequences for the capacity to sustain load and should hence be taken into account when training or racing young animals.

Age Factors↗
PubMed1980

High affinity of alpha-foetoprotein for arachidonate and other fatty acids.

Fatty acid analysis of purified bovine alpha-foetoprotein showed it to contain 2.7 mol of fatty acid/mol of alpha-foetoprotein. Purified alpha-foetoprotein focused at isoelectric point 4.8. Removal of bound ligands from alpha-foetoprotein by charcoal treatment changed its isoelectric point to 5.2. This change could be reversed by addition of exogenous fatty acids to the defatted alpha-foetoprotein. Albumin isolated from the same foetal calf serum source as alpha-foetoprotein contained 1.4 mol of fatty acid/mol of protein. alpha-Foetoprotein and albumin contained comparable amounts of fatty acids with 14 to 18 carbon atoms, but alpha-foetoprotein contained 16 times as much of the long-chain polyunsaturated fatty acids as albumin. alpha-Foetoprotein was found to have slightly higher affinity for palmitate and linoleate and severalfold higher affinity for arachidonate than albumin. These findings suggest that alpha-foetoprotein may play a role in the foetal metabolism of the long-chain polyunsaturated fatty acids.

Animals↗
PubMed1979

Lysozyme sensitivity of pantothenate-deficient Lactobacillus plantarum grown with exogenous fatty acids.

A pantothenic acid deficiency in Lactobacillus plantarum reduces lipid synthesis, prevents normal uptake and retention of extracellular amino acids and markedly increases sensitivity of these cells to lysozyme induced lysis. Pantothenate-deficient cells provided with exogenous fatty acids synthesize additional lipids and express nearly normal solute transport activities. The present study has shown that such cells retain a heightened sensitivity to lysozyme induced lysis. These observations indicate that the lysozyme sensitivity of pantothenate-deficient cells is not produced as in indirect effect of membrane lipid depletion, but represents an independent consequence of pantothenate insufficiency.

Fatty Acids↗
PubMed1979

Composition of lipids bound to pure cytochrome P-450 of cholesterol side-chain cleavage enzyme from bovine adrenocortical mitochondria.

Phospholipids bound to highly purified cytochrome P-450 from bovine adrenocortical mitochondria, part of the enzyme complex responsible for catalyzing the conversion of cholesterol to pregnenolone, have been examined for comparison with the bulk phospholipids of the mitochondria from the same tissue. In both cases, the major phospholipids are phosphatidylcholine (PC) (37%) and phosphatidylethanolamine (PE) (56%), as well as smaller amounts of sphingomyelin and diphosphatidylglycerol. The fatty acid compositions of the four classes of phospholipids and of the neutral lipids bound to the pure enzyme are indistinguishable from those of the respective mitochondrial lipids. They are also similar to those of mitochondria from other organs except for high levels of arachidonate and low levels of diphosphatidylglycerol.

Adrenal Cortex↗