A56 DEVELOPMENT OF A PROGNOSTIC SURVIVAL MODEL FOR PATIENTS DIAGNOSED WITH PANCREATIC CANCER IN ONTARIO

Background

Pancreatic adenocarcinoma (PAC) is a deadly disease with an overall 5-year survival of less than 8%. The current literature on patient outcomes are limited by small samples sizes and patients enrolled in clinical trials. There are no prognostic tools for patients with pancreatic cancer.

Purpose

To develop a prognostic survival model for patients with pancreatic cancer

Method

All patients with a diagnosis of pancreatic cancer cancer from January 2007 to December 2020 were identified through the Ontario Cancer Registry. The primary outcome was survival. The cohort was used to develop a multivariable cox proportional hazards regression model with baseline characteristics under a backward stepwise variable selection process to predict the risk of mortality. Covariates included patient age, sex, tumour location, cancer stage, treatment types, distance to a cancer centre, hospitalizations, comorbidities, access to family physician, and symptoms as captured using the Edmonton Symptom Assessment System datasets.

Result(s)

There was a total of 17,450 pancreatic cancer patients in the cohort, 48% of which were female and the mean age was 72 years. 44% of patients presented with a tumor in the head of the pancreas. Among those with stage data (44%), 24% were stage IV at diagnosis. Mean survival was approximately 0.7 years. Approximately 60% were hospitalized in the 3 months prior to diagnosis. Almost all patients had a family doctor rostered (95%). In multivariate analysis, key predictors of survival assessed at the time of diagnosis were age, sex, tumour location in the pancreas, stage at diagnosis, pain, appetite functional status and treatment choice (all p<0.001). Using these variables, we created a prediction model that can estimate one-year probability of death with high discrimination (area under the curve = 0.82, c-statistic 0.76).

Conclusion(s)

Our model accurately predicts one-year pancreatic cancer survival risk using clinical symptom and performance status data. The model has the potential to be a useful prognostic tool that can be completed by patients and their caregivers in support of patient-centered care.

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CIHR

Disclosure of Interest

None Declared

Breast cancer diagnosis and treatment wait times in specialized diagnostic units compared with usual care: a population-based study

Background

Breast assessment sites (bass) were developed to provide expedited and coordinated care for patients being evaluated for breast cancer (bca) in Ontario. We compared the diagnostic and treatment intervals for patients diagnosed at a bas and for those diagnosed through a usual care (uc) route.

Methods

This population-based, cross-sectional study of patients diagnosed with bca in Ontario during 2007-2015 used linked administrative data. "Diagnostic interval" was the time from the earliest cancer-related health care encounter before diagnosis to diagnosis; "treatment interval" was the time from diagnosis to treatment. Diagnosis at a bas was determined from the patient's biopsy and mammography institutions. Interval lengths for the bas and uc groups were compared using multivariable quantile regression, stratified by detection method.

Results

The diagnostic interval was shorter for patients who were bas-diagnosed than for those who were uc-diagnosed, with adjusted median differences of -4.0 days [95% confidence interval (ci): -3.2 days to -4.9 days] for symptomatic patients and -5.4 days (95% ci: -4.7 days to -6.1 days) for screen-detected patients. That association was modified by stage at diagnosis, with larger differences in patients with early-stage cancers. In contrast, the treatment interval was longer in patients who were bas-diagnosed than in those who were uc-diagnosed, with adjusted median differences of 4.2 days (95% ci: 3.8 days to 4.7 days) for symptomatic patients and 4.2 days (95% ci: 3.7 days to 4.8 days) for screen-detected patients.

Conclusions

Diagnosis of bca through a bas was associated with a shorter diagnostic interval, but a longer treatment interval. Although efficiencies in the diagnostic interval might help to reduce distress experienced by patients, the longer treatment intervals for patients who are bas-diagnosed remain a cause for concern.

Heparin Effect on Bone Density

In order to provide estimates of the risks of symptomatic osteoporosis and reduced bone density in premenopausal women treated with long-term (greater than 1 month) heparin therapy, we evaluated a cohort of 61 consecutive premenopausal women previously treated with long-term heparin (cases) and a group of controls matched for age, parity and duration between the last pregnancy and evaluation. All patients underwent dual photon absorptiometry of the lumbar spine and single photon absorptiometry of the wrist and most cases underwent plain lateral radiography of the thoracolumbar spine in order to exclude silent fractures. Although none of the cases suffered symptomatic fractures (0 of 61, 95% confidence intervals 0.0 to 5.9%), there was a significantly greater proportion of cases than controls with bone density below our pre-defined levels. The long-term implications of our findings are uncertain but because it is possible that the reduction in bone density predisposes women to fractures, this potential risk should be considered when treating women with long-term heparin.

Association between the time to surgery and survival among patients with colon cancer: A population-based study

Factors associated with time-to-surgery (TTS) and survival in colon cancer has not been well studied. Cancer Care Ontario recommends surgery within 42 days of diagnosis and that 90% of patients meet this benchmark. We describe factors associated with TTS and survival in routine clinical practice.

METHODS

Retrospective population-based cohort study of patients receiving elective colonic resection after diagnosis of colon cancer in Ontario, Canada from 2002 to 2008 followed until 2012. Factors associated with TTS were identified using multivariate log-binomial and Quantile regression at 42 days and 90th percentiles. The association between TTS and cancer-specific (CSS) and overall survival (OS) were examined using multivariate Cox regression.

RESULTS

4326 patients; median age 71 years and 52% male. Median TTS was 24 days (IQR 14-37); at the 90th percentile 56 days. Factors associated with TTS ≥ 42 days and >90th percentile included older age, co-morbid illness, surgeon volume, and stage I disease (P < 0.05 for all). In patients whose TTS was either at 42 days or 90th percentile, those ≥80 years old waited two weeks longer than those <60 years, individuals with co-morbid illness waited 10 days longer than without co-morbidity, and patients with stage I disease waited 10 days longer than those with stage IV disease (P < 0.05 for all). Delay in TTS > 42 days or >90th percentile was not associated with OS or CSS.

CONCLUSION

Age, co-morbidity, and stage of cancer are associated with TTS. There was no association between TTS and CSS or OS.

Alendronate for steroid-induced osteopenia in children with acute lymphoblastic leukaemia or non-Hodgkin’s lymphoma: results of a pilot study

Background/objectives. Osteopenia is a significant morbidity in children undergoing therapy for acute lymphoblastic leukaemia (ALL) or non-Hodgkin’s lymphoma (NHL). We conducted a pilot study to assess the impact of alendronate on whole body bone mineral content (WB-BMC), lumbar spine bone mineral density (LS-BMD), biochemical measures of bone mineral metabolism, as well as gross motor function and health-related quality of life (HRQL) in children undergoing therapy for ALL or NHL.

Methods. Ten children (nine boys) between the ages of 3.6 and 14.6 years, on identical maintenance chemotherapy for ALL or NHL were treated with oral alendronate once weekly, and daily calcium supplementation, for a period of six months. Outcome measures were WB-BMC and LSBMD; biochemical measures of bone mineral metabolism including plasma osteocalcin, C-terminal telopeptide of type I collagen (CTx), serum calcium, 25-hydroxy-vitamin D (25-OHD), and parathyroid hormone (PTH); as well as assessments of motor function and HRQL.

Results. A gain in Z score was observed in 7/9 evaluable patients for WB-BMC (mean increase of 0.49) and LS-BMD (0.51). Plasma osteocalcin and CTx showed a change in bone turnover favouring formation over resorption. Serum calcium and 25- OHD remained normal throughout treatment. After an initial spike, serum PTH returned to baseline values at week 4. Measures of motor function showed some improvement and there were modest gains in HRQL.

Conclusions. Alendronate therapy was tolerated well. Further study in a larger sample of children with ALL or NHL is warranted, in the context of a randomized clinical trial.

Abnormal error processing in depressive states: a translational examination in humans and rats

Depression has been associated with poor performance following errors, but the clinical implications, response to treatment and neurobiological mechanisms of this post-error behavioral adjustment abnormality remain unclear. To fill this gap in knowledge, we tested depressed patients in a partial hospital setting before and after treatment (cognitive behavior therapy combined with medication) using a flanker task. To evaluate the translational relevance of this metric in rodents, we performed a secondary analysis on existing data from rats tested in the 5-choice serial reaction time task after treatment with corticotropin-releasing factor (CRF), a stress peptide that produces depressive-like signs in rodent models relevant to depression. In addition, to examine the effect of treatment on post-error behavior in rodents, we examined a second cohort of rodents treated with JDTic, a kappa-opioid receptor antagonist that produces antidepressant-like effects in laboratory animals. In depressed patients, baseline post-error accuracy was lower than post-correct accuracy, and, as expected, post-error accuracy improved with treatment. Moreover, baseline post-error accuracy predicted attentional control and rumination (but not depressive symptoms) after treatment. In rats, CRF significantly degraded post-error accuracy, but not post-correct accuracy, and this effect was attenuated by JDTic. Our findings demonstrate deficits in post-error accuracy in depressed patients, as well as a rodent model relevant to depression. These deficits respond to intervention in both species. Although post-error behavior predicted treatment-related changes in attentional control and rumination, a relationship to depressive symptoms remains to be demonstrated.

Predicting pneumococcal community-acquired pneumonia in the emergency department: evaluation of clinical parameters

The aim of this study was to quantify the value of clinical predictors available in the emergency department (ED) in predicting Streptococcus pneumoniae as the cause of community-acquired pneumonia (CAP). A prospective, observational, cohort study of patients with CAP presenting in the ED was performed. Pneumococcal aetiology of CAP was based on either bacteraemia, or S. pneumoniae being cultured from sputum, or urinary immunochromatographic assay positivity, or positivity of a novel serotype-specific urinary antigen detection test. Multivariate logistic regression was used to identify independent predictors and various cut-off values of probability scores were used to evaluate the usefulness of the model. Three hundred and twenty-eight (31.0%) of 1057 patients with CAP had pneumococcal CAP. Nine independent predictors for pneumococcal pneumonia were identified, but the clinical utility of this prediction model was disappointing, because of low positive predictive values or a small yield. Clinical criteria have insufficient diagnostic capacity to predict pneumococcal CAP. Rapid antigen detection tests are needed to diagnose S. pneumoniae at the time of hospital admission.

Anatomical distribution of vertebral fractures: comparison of pediatric and adult spines

SUMMARY

We compared the distribution of vertebral fractures in adults and children and found that fractures occurred in different locations in the two age groups. This likely relates to the different shape of the immature spine.

INTRODUCTION

We hypothesized that the anatomical distribution of vertebral fractures (VF) would be different in children compared to adults.

METHODS

We compared the distribution of VF defined using the Genant semi-quantitative method (GSQ method) in adults (N = 221; 545 fractures) and in children early in the course of glucocorticoid therapy (N = 44; 94 fractures).

RESULTS

The average age in the adult cohort was 62.9 years (standard deviation (SD), 13.4 years), 26% was male, the mean lumbar spine Z-score was -1.0 (SD, 1.5), and the corresponding T-score was -2.4 (SD, 1.4). The pediatric cohort median age was 7.7 years (range, 2.1-16.6 years), the mean lumbar spine Z-score was -1.7 (SD, 1.5), 52% was male, and disease categories were acute lymphoblastic leukemia (66%), rheumatological conditions (21%), and nephrotic syndrome (14%). The VF distribution was biphasic in both populations, but the peaks differed in location. In adults, the peaks were at T7/T8 and at T12/L1. In children, the focus was higher in the thoracic spine, at T6/T7, and lower in the lumbar spine, at L1/L2. When children were assessed in two age-defined sub-groups, a biphasic VF distribution was seen in both, but the upward shift of the thoracic focus to T6 was observed only in the older group, with the highest rates of fracture present between ages 7 and 10 years.

CONCLUSIONS

These results suggest that the anatomical distribution of VF differs between children and adults, perhaps relating to the different shape of the immature spine, notably the changing ratio of kyphosis to lordosis.

Functional enrichment analysis with structural variants: pitfalls and strategies

Interpreting the phenotypic consequences of human structural variation remains challenging. Functional enrichment analysis, which can identify functional enrichments among genes affected by structural variants, is providing significant biological insights into the genotype-phenotype relationship. In this review, we discuss the different approaches and choices in the application of this technique to human structural variation. We consider the importance of choosing the right background distribution for detection, the significance of the gene selection criteria, the effects of tissue-specific gene length biases and discuss sources of functional annotations with a focus on Gene Ontology and mouse phenotypic resources. Throughout this review, we highlight potential sources of significant bias that are of particular concern to the analysis of structural variants, and illustrate the importance of examining the expectations upon which enrichment analysis techniques depend.

Bone mineral status after treatment of malignant lymphoma in childhood and adolescence

The relationship between bone mineral mass and cumulative dose of corticosteroids (CDC) was investigated in 42 children and adolescents treated for Hodgkin disease (HD; n = 22) and non-Hodgkin lymphoma (NHL; n = 20). The median age at the time of the study was 24.1 years for HD survivors and 14.1 years for NHL survivors. Dual-energy X-ray absorptiometry [bone mineral density of the lumbar spine (LS-BMD) expressed as Z-scores] and peripheral quantitative computed tomography at the distal radius [trabecular volumetric BMD (vBMD-trab)] were undertaken. Osteopenia (Z-score < -1.00) was found in 9/22 patients with HD and 10/20 with NHL, while 34% (HD = 6, NHL = 8) had a vBMD-trab below the normal range. The CDC correlated inversely with LS-BMD Z-score (r =-0.41, P = 0.007). There was a statistically significantly higher vBMD-trab in patients who received low (1-4 g/m(2)) compared with high (>or=20 g/m(2)) CDC (P = 0.031). Treatment of malignant lymphoma with high CDC is a risk factor for development of osteopenia.

Absorption, distribution, metabolism and excretion of the cholecystokinin-1 antagonist dexloxiglumide in the dog

Single oral doses of 14C-dexloxiglumide were rapidly and extensively absorbed in dogs and also eliminated rapidly with a short half-life. Following single intravenous doses, dexloxiglumide was characterised as a drug having a high clearance (30.7 and 27.0 ml/min/kg in males and females respectively), a low volume of distribution (Vss, 0.34 and 0.27 L/kg in males and females respectively) and a moderate systemic availability (about 33%). It was extensively bound to plasma proteins (89%). Dexloxiglumide is mainly cleared by the liver. Its renal clearance was minor. In only the kidney, liver and gastrointestinal tract, were concentrations of 14C generally greater than those in plasma. 14C concentrations generally peaked at 0.25h and declined rapidly during 24h being present only in a few tissues (such as the kidney, liver and gastrointestinal tract) at 24h. Single intravenous or oral doses were mainly excreted in the faeces (77-89%), mostly during 24h. Urine contained up to 7.5% dose. Mean recoveries during 7 days ranged between 93-97%. Biliary excretion of 14C was prominent (64% dose during 24h) in the disposition of 14C which was probably also subjected to some limited enterohepatic circulation. Unchanged dexloxiglumide was the major component in plasma. Urine and faeces contained several 14C-components amongst which unchanged dexloxiglumide was the most important (eg. about 55% dose in faeces). LC-MS/MS of urine and bile extracts showed that dexloxiglumide was metabolised mainly by O-demethylation and by conjugation with glucuronic acid.

Absorption, distribution, metabolism and excretion of the cholecystokinin-1 antagonist dexloxiglumide in the rat

Single oral doses of 14C-dexloxiglumide were rapidly and extensively absorbed in rats, and eliminated more slowly by females than by males. The respective half-lives were about 4.9 and 2.1 h. Following single intravenous doses, dexloxiglumide was characterised as a drug having a low clearance (6.01 and about 1.96 ml/min/kg in males and females respectively), a moderate volume of distribution (Vss, 0.98 and about 1.1 L/kg in males and females respectively) and a high systemic availability. It was extensively bound to plasma proteins (97%). Dexloxiglumide is mainly cleared by the liver. Its renal clearance was minor. In only the liver and gastrointestinal tract, were concentrations of 14C generally greater than those in plasma. Peak 14C concentrations generally occurred at 1-2 h in males and at 2-4 h in females. Tissue 14C concentrations then declined by severalfold during 24 h although still present in most tissues at 24 h but only in a few tissues (such as the liver and gastrointestinal tract) at 168 h. Decline of 14C was less rapid in the tissues of females than in those of males. Single intravenous or oral doses were mainly excreted in the faeces (87-92%), mostly during 24 h and more slowly from females than from males. Urines contained less than 11% dose. Mean recoveries during 7 days when 14C was not detectable in the carcass except in one female rat ranged between 93-101%. Biliary excretion of 14C was prominent (84-91% dose during 24 h) in the disposition of 14C which was also subjected to facile enterohepatic circulation (74% dose). Metabolite profiles in plasma and selected tissues differed. In the former, unchanged dexloxiglumide was the major component whereas in the latter, a polar component was dominant. Urine, bile and faeces contained several 14C-components amongst which unchanged dexloxiglumide was the most important (eg. up to 63% dose in bile). LC-MS/MS showed that dexloxiglumide was metabolised mainly by hydroxylation in the N-(3-methoxypropyl)pentyl sidechain and by O-demethylation followed by subsequent oxidation of the resulting alcohol to a carboxylic acid.

Efficacy of home-based exercise for improving quality of life among elderly women with symptomatic osteoporosis-related vertebral fractures

This randomized controlled trial was designed to investigate the effect of a 6-month home-based exercise program versus control (usual activities) on quality of life for postmenopausal women with osteoporosis who had at least one vertebral fracture. Twelve-month assessments of outcomes were completed to determine if women would continue exercising with minimal supervision and if benefit could be sustained. The home exercise program followed a "lifestyle exercise" approach where participants completed exercises 60 min per day, 3 days a week and could complete exercises in small periods of time throughout the day. Exercise activities included stretching, strength training and aerobics (i.e. walking). Participants were assessed at baseline, 6 months, and 12 months using the Osteoporosis Quality of Life Questionnaire (OQLQ), the Sickness Impact Profile (SIP), a balance test, and the Timed Up And Go test. Bone mineral density was assessed at baseline and 12 months for both the lumbar spine and femoral neck. Quality of life (OQLQ) improved over 6 months in the exercise group compared to the control group in the domains of symptoms (P=0.003), emotion (P=0.01) and leisure (P=0.03). Results from the balance test indicated a greater effect in the exercise group over 12 months (P<0.05). There were no significant differences between groups in measures of Timed Up and Go, SIP at 6 and 12 months, and femoral neck and lumbar spine bone mineral density at 12 months. Home-based exercise with minimal supervision improves quality of life in elderly women with vertebral fractures. Future research is needed to determine if home exercise programs reduce falls and fall-related injuries in the elderly.

Pharmacokinetics and metabolism of the cholecystokinin antagonist dexloxiglumide in male human subjects

1. Mean concentrations of total (14)C and of dexloxiglumide at the end of single 20-min infusion doses of (14)C-dexloxiglumide (200 mg) to four healthy male subjects were 18.5 microg eq x ml(-1) and 19.5 microg ml(-1) respectively. The mean plasma clearance (0.22 l h(-1) x kg(-1)) and mean volume of distribution (V(ss) = 0.18 l kg(-1)) were low. 2. Single oral doses of a solid formulation of (14)C-dexloxiglumide (200 mg) to the same subjects appeared to be rapidly and well absorbed. Mean peak plasma concentrations (C(max)) of total (14)C (2.8 microg eq x ml(-1)) and of dexloxiglumide (2.2 microg x ml(-1)) occurred at about 1.5 h. Systemic availabilities of the oral dose based on total (14)C and dexloxiglumide were 70 and 48%, respectively. Thus, a proportion of an oral dose was subjected to presystemic elimination and the absorbed dose mainly eliminated by metabolism. Binding of dexloxiglumide to plasma proteins was extensive (96.6-99.2%). 3. Total (14)C was excreted mainly in the faeces. Mass balance of (14)C excretion was almost complete within 7 days when a mean of > 93% of the dose had been recovered. After the intravenous (i.v.) dose, mean totals of 23.7 and 69.8% of the dose were excreted in urine and faeces, respectively, during 7 days, and 19.5 and 73.7% of the dose, respectively, after the oral dose. The data were consistent with biliary excretion and perhaps some enterohepatic circulation of conjugates of dexloxiglumide and at least one of its metabolites. 4. LC-MS/MS of urine extracts showed that dexloxiglumide was metabolized by oxidation and conjugation. The former included at least two metabolites formed by monohydroxylation in the N-(3-methoxypropyl) pentyl side chain, and O-demethylation of this side chain followed by subsequent oxidation of the resultant alcohol to the dicarboxylic acid. At least one glucuronide was also present in urine. The main components in faeces appeared to be dexloxiglumide and a dicarboxylic metabolite formed by O-demethylation followed by oxidation of the N-(3-methoxypropyl) side chain. Both compounds were identified as their corresponding methyl esters formed because acid and methanol were used in the extraction procedure. Dexloxiglumide and the dicarboxylic acid were presumably excreted in bile as the glucuronic acid conjugates.

Excessive degradation of type II collagen in articular cartilage in equine osteochondrosis

Articular osteochondrosis (OCD) occurs in both man and animals. The etiology remains to be determined. Studies of OCD lesions in animals may provide clues as to its pathogenesis. The aim of our study was to determine whether there was evidence for increased degradation namely proteoglycan (PG) release and type II collagen cleavage in articular cartilage harvested from OCD lesions. We examined ex vivo explants at post-mortem from equine OCD lesions and macroscopically normal site and age matched cartilage. These were cultured over a 10 day period in serum-free medium. Type II collagen cleavage was measured in articular cartilage and media using an Elisa assay to detect the COL2-3/4C(short) epitope, which is generated on cleavage of the triple helix of type II collagen by collagenases. PG release was measured by a dye-binding assay. Cumulative release of PG and COL2-3/4C(short) and their contents in cartilage at the end of the culture period were determined. In OCD lesions there was a significant increase in type II collagen cleavage by collagenase but no evidence for increase of PG degradation. These findings point to a selective increase in type II collagen cleavage by collagenases, in OCD lesions of the kind observed in osteoarthritis. Further work is needed to determine whether changes represent primary or secondary events in the pathogenesis of OCD.

Gene structure and expression of the mouse adipocyte enhancer-binding protein

The adipocyte enhancer-binding protein (AEBP1) is a transcriptional repressor with carboxypeptidase activity. AEBP1 expression is down-regulated during adipogenesis. Aortic carboxypeptidase-like protein (ACLP) is a non-nuclear isoform of AEBP1 that has an N-terminal extension of 380 amino acids. ACLP expression is up-regulated during vascular smooth muscle cell differentiation. To gain insight into the regulation of AEBP1 isoform expression, we have determined the structural organization of the mouse AEBP1 gene. This gene extends over 10 kb, has 21 exons, and gives rise to two mRNAs (AEBP1 and ACLP). The 9th intron is retained in the mature AEBP1 transcript. Thus, ACLP encodes an additional 380 amino acids N-terminal to the first ATG codon of AEBP1 which is located in exon 10. RT-PCR experiments showed that both transcripts are expressed ubiquitously in all mouse tissues examined, while Western blot analysis suggested that expression is translationally regulated. Our results provide evidence that two isoforms of AEBP1 with very different functions are produced by an alternative splicing mechanism. This represents a new example of regulation of subcellular localization by protein truncation.

Estimation of P-values for global alignments of protein sequences

MOTIVATION

The global alignment of protein sequence pairs is often used in the classification and analysis of full-length sequences. The calculation of a Z-score for the comparison gives a length and composition corrected measure of the similarity between the sequences. However, the Z-score alone, does not indicate the likely biological significance of the similarity. In this paper, all pairs of domains from 250 sequences belonging to different SCOP folds were aligned and Z-scores calculated. The distribution of Z-scores was fitted with a peak distribution from which the probability of obtaining a given Z-score from the global alignment of two protein sequences of unrelated fold was calculated. A similar analysis was applied to subsequence pairs found by the Smith-Waterman algorithm. These analyses allow the probability that two protein sequences share the same fold to be estimated by global sequence alignment.

RESULTS

The relationship between Z-score and probability varied little over the matrix/gap penalty combinations examined. However, an average shift of +4.7 was observed for Z-scores derived from global alignment of locally-aligned subsequences compared to global alignment of the full-length sequences. This shift was shown to be the result of pre-selection by local alignment, rather than any structural similarity in the subsequences. The search ability of both methods was benchmarked against the SCOP superfamily classification and showed that global alignment Z-scores generated from the entire sequence are as effective as SSEARCH at low error rates and more effective at higher error rates. However, global alignment Z-scores generated from the best locally-aligned subsequence were significantly less effective than SSEARCH. The method of estimating statistical significance described here was shown to give similar values to SSEARCH and BLAST, providing confidence in the significance estimation.

AVAILABILITY

Software to apply the statistics to global alignments is available from http://barton.ebi.ac.uk.

CONTACT

geoff@ebi.ac.uk

Scooter injuries in children

OBJECTIVES

To study the causes, patterns of injury and use of safety equipment in children presenting with 'push/kick' scooter-related injuries. To draw comparisons with in-line skate, skateboard and bicycle injuries and to suggest strategies for injury prevention.

METHODS

A retrospective review of medical data was undertaken for 12 consecutive months to September 2000. All children aged < 15 years who had attended the Sydney Children's Hospital with scooter, in-line skate (rollerblade), skateboard or bicycle injuries were identified. Children with scooter injuries for the latter 6 month period were contacted by telephone and interviewed, together with their parents, using a structured questionnaire.

RESULTS

There was a marked rise in the number of scooter injuries from October 1999 to September 2000. Sixty-one per cent of these injuries occurred during the final 3 months of the study period, making scooters the most common cause of injury in the studied groups for this period. Forty-two per cent of scooter injuries were fractures. Only 3% of children used safety equipment at the time of injury, despite 86% owning some form of safety equipment. Children were less likely to use safety equipment with a scooter than with any other form of activity studied. (Chi-squared P=0.000).

CONCLUSIONS

Scooters are a common cause of childhood injury, resulting in injury patterns similar to those caused by in-line skates, skateboards and bicycles. Safety equipment is rarely worn when scooters are ridden. Injury patterns and riding styles suggest that if existing guidelines for in-line skating, skateboarding and bicycling are modified and applied to scooters, a reduction in injury numbers may be achieved.

Abilities and attainment in Smith-Magenis syndrome

This study reports on cognitive abilities and attainment in 29 children and 21 adults with Smith-Magenis syndrome. There were 13 boys and 16 girls aged 6 to 16 years, and nine men and 12 women aged 16 to 52 years. All had mild to severe learning disabilities* with no differences overall between verbal and performance skills, but with a particular profile of cognitive strengths and weaknesses. Levels of attainment and of adaptive behaviour were strikingly low, and the group of adults emerged as much more dependent on carers than might have been expected from their general level of intellectual functioning. Reasons for this discrepancy are explored in terms of the severe behavioural difficulties characteristic of the syndrome.

Selective assembly and remodelling of collagens II and IX associated with expression of the chondrocyte hypertrophic phenotype

The assembly and resorption of the extracellular matrix in the physis of the growth plate are poorly understood. By examining isolated fetal growth plate chondrocytes in culture and using immunochemical methods we show that type II collagen, proteoglycan aggrecan, and type IX collagen are assembled into a matrix that is initially enriched in type II collagen over proteoglycan and type IX collagen. When compared to the content of the COL2 domain in the alpha(1)(IX) chain it is evident that the majority ( 90%) of type IX molecules lack the NC4 domain unlike in articular cartilage. During matrix assembly the molar ratio of type II/COL2 of alpha(1)(IX) varied from 25:1 to 2.5:1. Following expression of the hypertrophic phenotype (initiation of type X collagen synthesis) there are parallel changes in both collagen and proteoglycan contents (inversely related to collagenase cleavage of type II collagen). The NC4 domain is then selectively, rapidly and irreversibly removed as mineralization is initiated, leaving the alpha(1)(IX) chain COL2 domain. Subsequently as mineralization progresses type II and type IX collagen (COL2 domain), but not the proteoglycan aggrecan, are resorbed coincident with a markedly increased cleavage of type II collagen by collagenase as mineral is deposited in the matrix. This study, therefore reveals a carefully orchestrated series of events in matrix assembly and resorption that prepares the extracellular matrix for mineralization.

A radiation hybrid map of the rat genome containing 5,255 markers

A whole-genome radiation hybrid (RH) panel was used to construct a high-resolution map of the rat genome based on microsatellite and gene markers. These include 3,019 new microsatellite markers described here for the first time and 1,714 microsatellite markers with known genetic locations, allowing comparison and integration of maps from different sources. A robust RH framework map containing 1,030 positions ordered with odds of at least 1,000:1 has been defined as a tool for mapping these markers, and for future RH mapping in the rat. More than 500 genes which have been mapped in mouse and/or human were localized with respect to the rat RH framework, allowing the construction of detailed rat-mouse and rat-human comparative maps and illustrating the power of the RH approach for comparative mapping.

Heparin improves gas exchange during experimental acute lung injury in newborn piglets

Although intrapulmonary fibrin deposition is a pathognomonic feature of acute lung injury, it remains uncertain whether thrombin inhibitors affect clinically important outcomes. We hypothesized that both heparin and antithrombin (AT) concentrate improve gas exchange during experimental respiratory distress syndrome. We also tested whether combination therapy is more beneficial than monotherapy. Forty-eight newborn piglets were randomized within 12 litters to one of four groups in a factorial design: (1) AT; (2) heparin; (3) AT plus heparin; (4) untreated control animals. After lung lavage and 4 h of barovolutrauma, mechanical ventilation was continued for 24 h during which ventilator pressures and inspired oxygen were adjusted to maintain normal blood gases. The arterial/ alveolar oxygen tension ratio (a/A ratio) and the ventilator efficiency index (VEI) at 18 and 24 h were compared by repeated measures analysis of variance (ANOVA). In contrast to our hypothesis, only heparin improved gas exchange, and we found little evidence of an interaction with AT. The a/A ratio was 0.48 +/- 0.27 (mean +/- SD) in the presence of heparin versus 0.33 +/- 0.26 in its absence; p = 0.01. Corresponding VEI was 0.30 +/- 0.12 versus 0.25 +/- 0.14; p = 0.04. Hyaline membrane formation was also decreased in heparin-treated animals (p = 0.02).

A physical map of 30,000 human genes

A map of 30,181 human gene-based markers was assembled and integrated with the current genetic map by radiation hybrid mapping. The new gene map contains nearly twice as many genes as the previous release, includes most genes that encode proteins of known function, and is twofold to threefold more accurate than the previous version. A redesigned, more informative and functional World Wide Web site (www.ncbi.nlm.nih.gov/genemap) provides the mapping information and associated data and annotations. This resource constitutes an important infrastructure and tool for the study of complex genetic traits, the positional cloning of disease genes, the cross-referencing of mammalian genomes, and validated human transcribed sequences for large-scale studies of gene expression.

Induction of arthritis in BALB/c mice by cartilage link protein: involvement of distinct regions recognized by T and B lymphocytes

Both type II collagen and the proteoglycan aggrecan are capable of inducing an erosive inflammatory polyarthritis in mice. In this study we provide the first demonstration that link protein (LP), purified from bovine cartilage, can produce a persistent, erosive, inflammatory polyarthritis when injected repeatedly intraperitoneally into BALB/c mice. We discovered a single T-cell epitope, located within residues 266 to 290 of bovine LP (NDGAQIAKVGQIFAAWKLLGYDRCD), which is recognized by bovine LP-specific T lymphocytes. We also identified three immunogenic regions in bovine LP that contain epitopes recognized by antibodies in hyperimmunized sera. One of these B-cell regions is found in the most species-variable domain of LP (residues 1 to 36), whereas the other epitopes are located in the most conserved regions (residues 186 to 230 and 286 to 310). The latter two regions contain an AGWLSDGSVQYP motif shared by the G1 globulin domain of aggrecan core protein, versican, neurocan, glial hyaluronan-binding protein, and the hyaluronan receptor CD44. Our data reveal that the induction of arthritis is associated with antibody reactivities to B-cell epitopes located at residues 1 to 19. Together, these observations show that another cartilage protein, LP, like type II collagen and the proteoglycan aggrecan, is capable of inducing an erosive inflammatory arthritis in mice and that the immunity to LP involves recognition of both T- and B-cell epitopes. This immunity may be of importance in the pathogenesis of inflammatory joint diseases, such as juvenile rheumatoid arthritis, in which cellular immunity to LP has been demonstrated.

Autoimmunity to cartilage link protein in patients with rheumatoid arthritis and ankylosing spondylitis

OBJECTIVE

To determine whether patients with rheumatoid arthritis (RA) and ankylosing spondylitis (AS) express cellular immunity to cartilage link protein (LP).

METHODS

LP was purified from human fetal epiphyseal and bovine adult nasal cartilage. It was used in proliferation assays with the peripheral blood lymphocytes (PBL) isolated from 83 patients with RA, 21 patients with AS, and 30 healthy controls.

RESULTS

Patients with RA (34%) and AS (71%) expressed a significantly higher prevalence of cellular immune responses to human LP compared with the healthy control group (13%). Such significant differences were not observed for bovine LP. Half the patients with RA responding to LP exhibited cellular immunity to both human and bovine protein. In the AS group, PBL from a majority of responders to LP recognized only human LP.

CONCLUSION

These data suggest that LP is a potential autoantigen in the development of RA and AS and that cellular immune reactivity to common and distinct LP epitopes in patients with RA and AS may play a role in the pathogenesis of these diseases.

Arthritis induced by proteoglycan aggrecan G1 domain in BALB/c mice. Evidence for t cell involvement and the immunosuppressive influence of keratan sulfate on recognition of t and b cell epitopes

Our previous work showed that the proteoglycan aggrecan can induce erosive polyarthritis and spondylitis in BALB/c mice, and that the G1 domain of the proteoglycan aggrecan (G1) is the arthritogenic region. In this study, two T cell epitopes residing on G1 within residues 70-84 (peptide G5) and 150-169 (peptide G9) were identified using synthetic peptides and aggrecan-specific T cell lines. Two G1-specific T cell hybridomas exclusively responded to peptide G5. When the G5-specific T cell line was injected intraperitoneally into BALB/c mice, it induced acute inflammatory arthritis in joints, but only in those that had been injected with the epitope recognized by these T cells. Furthermore, we also demonstrate that the keratan sulfate chain(s) (KS) on G1 possess immunosuppressive properties with respect to T and B cell epitope recognition. T cell lines that recognize both G1 and peptide G5 show an increased response to G1 after KS is removed. Antibodies in hyperimmune sera of mice immunized with G1 show increased epitope recognition (quantitative and qualitative) after KS removal before immunization. These studies reveal that a T cell line specific to an epitope on the G1 domain of aggrecan, also recognizing a corresponding mouse G1 epitope, can induce arthritis by adoptive transfer and homing to the intraarticular epitope, thereby implicating T cells in arthritis development caused by immunity to the G1 domain of aggrecan. Moreover, the presence of KS on G1 can inhibit arthritis development by suppressing T and B cell epitope recognition.

Homozygous protein C deficiency: description of a new mutation and successful treatment with low molecular weight heparin

We present a kindred with a new mutation of the protein C gene, in which the proband had an unusual clinical presentation. The relationship between warfarin induced skin necrosis and level of anticoagulation was investigated. The pharmacokinetics of protein C concentrate was assessed to determine frequency of replacement therapy. The clinical and biochemical efficacy of therapy with low molecular weight heparin (LMWH) was assessed. The effect of long-term LMWH on bone density in the growing child was monitored using whole body densitometry. Warfarin therapy required an INR of greater than 3.5 to avoid skin necrosis. If protein C replacement was to be used, doses of 100 U/kg/day would have been required to maintain protein C levels consistently at or above 0.20 U/ml. While receiving prophylactic therapy with LMWH for almost 3 years, there were no episodes of recurrent thrombosis, no skin necrosis and no bleeding. Biochemical markers of in vivo thrombin generation were suppressed and within the normal range. Bone density continued to increase at the normal rate throughout the treatment period. LMWH is an effective form of long-term therapy for homozygous protein C deficient patients with measurable protein C levels.

Immunity to cartilage link protein in patients with juvenile rheumatoid arthritis

OBJECTIVE

To determine whether children with juvenile rheumatoid arthritis (JRA) express cellular immunity to cartilage link protein.

METHODS

Link protein was purified from human fetal epiphyseal and bovine adult nasal cartilage. It was used in proliferation assays with the peripheral blood lymphocytes isolated from 54 children with JRA and 22 nonarthritic controls.

RESULTS

Patients with JRA expressed a significantly higher prevalence of cellular proliferation to human link protein compared with the control group, independent of whether they had pauciarticular, polyarticular, or systemic disease. In the case of bovine link protein, significant differences were only noted for the polyarticular group. There was significant correlation between the immunity to bovine and to human link proteins. Furthermore, immune responses to both molecules correlated with measures of joint disease activity.

CONCLUSION

These results suggest that immunity to link protein may play a role in the pathogenesis of JRA.

Altered mineral metabolism and bone mass in children during treatment for acute lymphoblastic leukemia

Children with acute lymphoblastic leukemia (ALL) often develop bone pain, abnormal gait, and unusual fractures while in remission and receiving continuing chemotherapy. A prospective longitudinal cohort study was undertaken of bone mass and biochemical mineral status in 40 consecutive children (27 male, 13 female, aged 0.3-17.0 years) receiving therapy on the Dana-Farber Cancer Institute protocol 87-01. Radiography, lumbar spine dual-photon absorptiometry, and biochemical measurements of mineral status were performed at diagnosis and at 6-month intervals throughout 24 months of chemotherapy. Eleven patients were not completely evaluated (4 deaths and 7 off study). Radiographic evidence of osteopenia was observed in 10, 64, and 76% at diagnosis, 12 and 24 months, respectively. Fractures occurred in 39% of children during treatment. Reduction in bone mineral content (BMC), as measured by Z scores, occurred in 64% of patients and was most severe in those greater than 11 years of age at diagnosis. Reduction in BMC during the first 6 months of therapy had a positive predictive value of 64%, while an increase in BMC had a negative predictive value of 82% for subsequent fracture. By 6 months of therapy, 31/37 (84%) children were hypomagnesemic, of whom 16 (52%) were hypermagnesuric. Plasma osteocalcin was subnormal at diagnosis in 29/40 (73%) but increased to normal by 6 months of treatment. Vitamin D status was normal throughout, but plasma 1,25-dihydroxyvitamin D remained subnormal in greater than 70% of children. Urinary cross-link N-telopeptide was normal at diagnosis and became elevated in 58% of children by the end of therapy. Suppressed bone mineralization is evident at diagnosis in a minority of children with ALL. Skeletal morbidity and a reduction in bone mineral mass become more prevalent during treatment, with increased bone resorption, perhaps mainly as a consequence of corticosteroid administration.

Vitamin D and calcium in the prevention of corticosteroid induced osteoporosis: a 3 year followup

OBJECTIVE

To determine the efficacy and safety of vitamin D 50,000 units/week and calcium 1,000 mg/day in the prevention of corticosteroid induced osteoporosis.

METHODS

A minimized double blind, placebo controlled trial in corticosteroid treated subjects in a tertiary care university affiliated hospital. The sample was 62 subjects with polymyalgia rheumatica, temporal arteritis, asthma, vasculitis, or systemic lupus erythematosus. The primary outcome measure was the percentage change in bone mineral density (BMD) of the lumbar spine in the 2 treatment groups from baseline to 36 mo followup.

RESULTS

BMD of the lumbar spine in the vitamin D and calcium treated group decreased by a mean (SD) of 2.6% (4.1%) at 12 mo, 3.7% (4.5%) at 24 mo, and 2.2% (5.8%) at 36 mo. In the placebo group there was a decrease of 4.1% (4.1%) at 12 mo, 3.8% (5.6%) at 24 mo, and 1.5% (8.8%) at 36 mo. The observed differences between groups were not statistically significant. The difference at 36 mo was-0.693% (95% CI -5.34, 3.95).

CONCLUSION

Vitamin D and calcium may help prevent the early loss of bone seen in the lumbar spine as measured by densitometry of the lumbar spine. Longterm vitamin D and calcium in those undergoing extended therapy with corticosteroids does not appear to be beneficial.

Immunity to the G1 globular domain of the cartilage proteoglycan aggrecan can induce inflammatory erosive polyarthritis and spondylitis in BALB/c mice but immunity to G1 is inhibited by covalently bound keratan sulfate in vitro and in vivo

Earlier work from this laboratory showed that the human proteoglycan aggrecan from fetal cartilages can induce a CD4+ T cell-dependent inflammatory polyarthritis in BALB/c mice when injected after removal of chondroitin sulfate chains. Adult keratan sulfate (KS)-rich aggrecan does not possess this property. We found that two CD4+ T cell hybridomas (TH5 and TH14) isolated from arthritic mice recognize bovine calf aggrecan and the purified G1 domain of this molecule, which also contains a portion of the interglobular domain to which KS is bound. These hybridoma responses to G1 are enhanced by partial removal of KS by the endoglycosidase keratanase or by cyanogen bromide cleavage of core protein. KS removal results in increased cellular uptake by antigen-present cells in vitro. After removal of KS by keratanase, G1 alone can induce a severe erosive polyarthritis and spondylitis in BALB/c mice identifying it as an arthritogenic domain of aggrecan. The presence of KS prevents induction of arthritis presumably as a result of an impaired immune response as observed in vitro. These observations not only identify the arthritogenic properties of G1 but they also point to the importance of glycosylation and proteolysis in determining the arthritogenicity of aggrecan and fragments thereof.

Reproducibility of dual-energy x-ray absorptiometry

The purpose of this investigation was to determine the short-term reproducibility of measurements of whole-body and subregion bone mass and density, as well as body composition, made by dual energy x-ray absorptiometry. Bone mineral content, bone mineral density and body composition were measured on two occasions, 1 to 2 weeks apart, in 21 women (average age, 20.9 [standard deviation 1.6] years). The method errors of the duplicate measurements, expressed as a percentage of the combined mean values from the two sets of measurements (i.e., as a coefficient of variation), for whole-body bone mineral content, bone mineral density, lean tissue mass and fat mass were 1.6%, 1.1%, 1.4% and 1.8% respectively. The method errors for bone mineral density in the hip were 2.2%, 1.1% and 2.5% for the neck, trochanter and Ward's triangle respectively. On the basis of the method errors and the expected treatment effects, the sample sizes needed for intervention trials (e.g., exercise training) were calculated. All of the whole-body and most of the subregion bone mineral density and lean tissue mass measurements made by dual-energy x-ray absorptiometry were sufficient for detecting the small changes (about 2%) expected in trials with 20 subjects, whereas measurements of subregion bone mineral content and fat mass were less precise.

Increased damage to type II collagen in osteoarthritic articular cartilage detected by a new immunoassay

A new immunoassay was developed to detect denaturation of type II collagen in osteoarthritis (OA). A peptide, alpha 1 (II)-CB11B, located in the CB11 peptide of type II collagen, was synthesized and used to produce a monoclonal antibody (COL2-3/4m) of the IgG1 (kappa) isotype. This reacts with a defined epitope in denatured but not native type II collagen and the alpha 3 chain of type XI collagen. The latter is present in very small amounts (about 1% wt/wt) in cartilage relative to the alpha 1 (II) chain. By using an enzyme-linked immunosorbent assay, type II collagen denaturation and total type II collagen content were determined. The epitope recognized by the antibody was resistant to cleavage by alpha-chymotrypsin and proteinase K which were used to extract alpha 1 (II)-CB11B from the denatured (alpha-chymotrypsin soluble) and residual native (proteinase K soluble) collagen alpha-chains, respectively, present in human femoral articular cartilage. Type II collagen content was significantly reduced from a mean (range) of 14% (9.2-20.8%) of wet weight in 8 normal cartilages to 10.3% (7.4-15.0%) in 16 OA cartilages. This decrease, which may result in part from an increased hydration, was accompanied by an increase in the percent denaturation of type II collagen in OA to 6.0% of total type II collagen compared with 1.1% in normal tissue. The percent denaturation was ordinarily greater in the more superficial zone than in the deep zone of OA cartilage.

Benign lymphoepithelial lesions of the parotid

Persistent generalized lymphadenopathy has been well described in patients with seropositivity to the human immunodeficiency virus (HIV). Moreover, isolated enlargement of the parotid gland and parotid lymphadenopathy have been noted much more frequently over the past few years. Histologically, these lesions demonstrate follicular hyperplasia, cystic dilatation of the ducts lined by pseudo-stratified squamous epithelium, and lymphocytic infiltrates. They are generally considered to be benign lymphoepithelial lesions of the parotid or hyperplastic periparotid lymph nodes. The relationship of this entity to the AIDS-related complex (ARC) and the subsequent development of AIDS is not clear. Over the past 7 years, we have seen 50 patients with parotid enlargement in whom the diagnosis of benign lymphoepithelial lesion was made. Fine-needle aspiration was performed in 32 patients. Although not conclusively diagnostic, needle aspirates ruled out primary salivary glandular pathology. Most patients gave a history of intravenous drug abuse. HIV tests have been performed on a routine basis only in the last 2 years, and these were positive in the majority of the patients. Thirty-five patients underwent surgical excision. In the initial 20 patients, we routinely performed parotid exploration, identification of the facial nerve, and superficial parotidectomy. In the last 15 patients, we changed our surgical approach to parotid exploration and excision of the mass in the tail of the parotid. The exposure of the posterior belly of the digastric muscle, with identification and removal of the deep jugular node, has become routine. In each case, we found an enlarged lymph node in the deep jugular region, which was not clinically palpable preoperatively. The rate of surgical complications was minimal, and, after resection of the mass, patients improved symptomatically. If the patient shows obvious signs of AIDS, a nonsurgical approach with repeated aspirations should be considered, and treatment with zidovudine offered.

The induction of arthritis in mice by the cartilage proteoglycan aggrecan: Roles of CD4+ and CD8+ T cells

Peripheral arthritis is produced in BALB/c mice after hyperimmunization with the cartilage proteoglycan aggrecan (PG). Adoptive transfer studies have suggested the roles of T cells including CD8+ T cells in the disease process. To evaluate the roles of CD4+ and CD8+ T cell subsets in vivo in the induction of this disease by immunization, PG-immunized mice were treated with isotype-controlled rat IgG2b monoclonal anti-CD4 or anti-CD8 antibodies, or were left untreated. CD4+ T cell depletion resulted in total inhibition of the disease with markedly decreased anti-PG antibody responses. CD8+ T cell depletion, however, significantly enhanced the severity of the disease without affecting peak anti-PG antibodies, as compared to the control mice. These results demonstrate a crucial role for CD4+ T cells in the pathogenesis of this disease. However, CD8+ T cells do not seem to be required for the induction of arthritis by immunization but instead may play an immunoregulatory role.

Characterization of proteoglycan-reactive T cell lines and hybridomas from mice with proteoglycan-induced arthritis

Hyperimmunization with chondroitin sulfate-depleted fetal human cartilage proteoglycan (HFPG) leads to the development of peripheral arthritis and spondylitis in BALB/c mice. Chondroitin-sulfate-depleted adult human cartilage proteoglycan (HAPG) is much less effective at inducing arthritis. These observations suggest age differences in the presence of arthritogenic proteoglycan (PG) epitopes. Earlier studies from this laboratory have indicated an important role for PG-reactive T cells in the pathogenesis of this arthritis model. To investigate further the cellular immunity to PG in mice, two T cell lines, JY.A and JY.D, and two T cell hybridomas, TH5 and TH14, were isolated from mice with PG-induced arthritis and characterized. Two patterns of reactivity to PG emerged from the analysis of these T cells. One pattern, as demonstrated by the T cell line JY.D and the two T cell hybridomas, TH5 and TH14, was characterized by reactivity to HFPG, HAPG, chondroitin sulfate-depleted bovine cartilage PG, the G1 domain (hyaluronate binding region) of bovine cartilage PG and bovine link protein. The epitope(s) recognized by these T cells appear to be part of the homologous regions shared between the G1 domain and the link protein. The second pattern of reactivity, as demonstrated by the T cell line JY.A, was characterized by reactivity to HFPG but not to HAPG or the other PG Ag or bovine link protein. All the T cell lines and hybridomas had a CD4+, CD8- phenotype, possibly belonged to the TH1 subset (IL-2+, IL-4-), and were MHC class II restricted. These studies indicate that HFPG has T cell epitopes in common with HAPG (such as in the G1 domain) and different than those in HAPG. The significance of this data in terms of PG structure, changes with age, and induction of arthritis remains to be established.

Characterization of proteoglycan-reactive T cell lines and hybridomas from mice with proteoglycan-induced arthritis

Hyperimmunization with chondroitin sulfate-depleted fetal human cartilage proteoglycan (HFPG) leads to the development of peripheral arthritis and spondylitis in BALB/c mice. Chondroitin-sulfate-depleted adult human cartilage proteoglycan (HAPG) is much less effective at inducing arthritis. These observations suggest age differences in the presence of arthritogenic proteoglycan (PG) epitopes. Earlier studies from this laboratory have indicated an important role for PG-reactive T cells in the pathogenesis of this arthritis model. To investigate further the cellular immunity to PG in mice, two T cell lines, JY.A and JY.D, and two T cell hybridomas, TH5 and TH14, were isolated from mice with PG-induced arthritis and characterized. Two patterns of reactivity to PG emerged from the analysis of these T cells. One pattern, as demonstrated by the T cell line JY.D and the two T cell hybridomas, TH5 and TH14, was characterized by reactivity to HFPG, HAPG, chondroitin sulfate-depleted bovine cartilage PG, the G1 domain (hyaluronate binding region) of bovine cartilage PG and bovine link protein. The epitope(s) recognized by these T cells appear to be part of the homologous regions shared between the G1 domain and the link protein. The second pattern of reactivity, as demonstrated by the T cell line JY.A, was characterized by reactivity to HFPG but not to HAPG or the other PG Ag or bovine link protein. All the T cell lines and hybridomas had a CD4+, CD8- phenotype, possibly belonged to the TH1 subset (IL-2+, IL-4-), and were MHC class II restricted. These studies indicate that HFPG has T cell epitopes in common with HAPG (such as in the G1 domain) and different than those in HAPG. The significance of this data in terms of PG structure, changes with age, and induction of arthritis remains to be established.