Biomedical subjects

D O Clegg

Publications and source records attributed to D O Clegg.

At least 55 records · Page 3Linked to original sources

PubMed1995

Minocycline in rheumatoid arthritis. A 48-week, double-blind, placebo-controlled trial. MIRA Trial Group.

OBJECTIVE: To assess the safety and efficacy of minocycline in the treatment of rheumatoid arthritis. DESIGN: A double-blind, randomized, multicenter, 48-week trial of oral minocycline (200 mg/d) or placebo. SETTING: 6 clinical centers in the United States. PATIENTS: 219 adults with active rheumatoid arthritis who had previous limited treatment with disease-modifying drugs. MEASUREMENTS: As the primary outcomes, 60 diarthrodial joints were examined for tenderness, and 58 joints were examined for swelling (hips excluded). Grip strength, evaluator's global assessment, morning stiffness, Modified Health Assessment Questionnaire, patient's global assessment, hematocrit, erythrocyte sedimentation rate, platelet count, and IgM rheumatoid factor levels were also assessed; radiographs of both hands and wrists were taken. RESULTS: 109 and 110 patients were randomly assigned to receive minocycline and placebo, respectively. At entry, demographic, clinical, and laboratory measurements were similar in both groups. Most patients had mild to moderate disease activity and some evidence of destructive disease. At the week 48 visit, 79% of the minocycline group and 78% of the placebo group continued to receive the study medication. At 48 weeks, more patients in the minocycline group than in the placebo group showed improvement in joint swelling (54% and 39%) and joint tenderness (56% and 41%) (P < 0.023 for both comparisons). The minocycline group also showed greater improvement in hematocrit, erythrocyte sedimentation rate, platelet count, and IgM rheumatoid factor levels (all P values < 0.001), and more patients receiving minocycline had laboratory values within normal ranges at 48 weeks. For the remaining outcomes, P values ranged from 0.04 to 0.76, all greater than the critical value of 0.005 (Bonferroni adjustment for multiple comparisons). The frequency of reported side effects was similar in both groups, and no serious toxicity occurred. CONCLUSIONS: Minocycline was safe and effective for patients with mild to moderate rheumatoid arthritis. Its mechanisms of action remain to be determined.

Administration, Oral↗

PubMed1995

Non-linkage of a T-cell receptor gamma chain microsatellite (D7S485) to rheumatoid arthritis in multiplex families.

A highly informative microsatellite marker, D7S485, from the T-cell receptor gamma (TCRG) locus, has been used to study segregation of TCRG genes in 26 multiplex rheumatoid arthritis (RA) families. We used the sib-pair method to assess excess identity-by-descent sharing among affected members in these families and the LINKAGE package of programs was used to calculate two-point lod scores for the D7S485 marker. There was no evidence for segregation of TCRG genes with RA in affected siblings and significantly negative lod scores were obtained from linkage analyses using both autosomal dominant and recessive models of inheritance.

Adolescent↗

PubMed1995

Differential localization and functional role of calsequestrin in growing and differentiated myoblasts.

Calsequestrin (CSQ) is the low affinity, high capacity Ca(2+)-binding protein concentrated within specialized areas of the muscle fiber sarcoplasmic reticulum (a part of the ER) where it is believed to buffer large amounts of Ca2+. Upon activation of intracellular channels this Ca2+ pool is released, giving rise to the [Ca2+]i increases that sustain contraction. In order to investigate the ER retention and the functional role of the protein, L6 rat myoblasts were infected with a viral vector with or without the cDNA of chicken CSQ, and stable clones were investigated before and after differentiation to myotubes. In the undifferentiated L6 cells, expression of considerable amounts of heterologous CSQ occurred with no major changes of other ER components. Ca2+ release from the ER, induced by the peptide hormone vasopressin, remained however unchanged, and the same occurred when other treatments were given in sequence to deplete the ER and other intracellular stores: with the Ca2+ pump blocker, thapsigargin; and with the Ca2+ ionophore, ionomycin, followed by the Na+/H+ ionophore, monensin. The lack of effect of CSQ expression on the vasopressin-induced [Ca2+]i responses was explained by immunocytochemistry showing the heterologous protein to be localized not in the ER but in large vacuoles of acidic content, positive also for the lysosomal enzyme, cathepsin D, corresponding to a lysosomal subpopulation. After differentiation, all L6 cells expressed small amounts of homologous CSQ. In the infected cells the heterologous protein progressively decreased, yet the [Ca2+]i responses to vasopressin were now larger with respect to both control and undifferentiated cells. This change correlated with the drop of the vacuoles and with the accumulation of CSQ within the ER lumen, where a clustered distribution was observed as recently shown in developing muscle fibers. These results provide direct evidence for the contribution of CSQ, when appropriately retained, to the Ca2+ capacity of the rapidly exchanging, ER-located Ca2+ stores; and for the existence of specific mechanism(s) (that in L6 cells develop in the course of differentiation) for the ER retention of the protein. In the growing L6 myoblasts the Ca(2+)-binding protein appears in contrast to travel along the exocytic pathway, down to post-Golgi, lysosome-related vacuoles which, based on the lack of [Ca2+]i response to ionomycin-monensin, appear to be incompetent for Ca2+ accumulation.

Animals↗

PubMed1995

Integrin alpha 2 beta 1 mediates interactions between developing embryonic retinal cells and collagen.

In the developing nervous system, the extracellular matrix provides a source of extrinsic cues to guide determination of cell fate, neuroblast migration, axon outgrowth and synapse formation. In the neural retina, undifferentiated neuroepithelial precursor cells contact extracellular matrix that contains multiple collagen types. Collagens have been shown to support retinal cell adhesion and neurite outgrowth, but the integrin receptors mediating neuronal responses are not understood. Here we provide evidence that integrin alpha 2 beta 1 acts as a collagen receptor in the developing avian retina and examine its expression pattern. Using a recently described monoclonal antibody, MEP-17, alpha 2 protein was detected in the developing retina by immunofluorescence in tissue sections and dissociated cells, and by immunoprecipitation. At embryonic day 4 (E4), when the majority of retinal cells are undifferentiated neuroepithelial cells, alpha 2 immunoreactivity in sections was widespread and about half of cells dissociated in culture were alpha 2 positive. At E6, after the retinal ganglion cell layer had differentiated, immunoreactivity in sections decreased in the central, more developed portion of the retina and 25% of dissociated cells were alpha 2 positive. E6 retinal ganglion cells, identified by neurofilament immunoreactivity, did not express detectable alpha 2 immunoreactivity. Immunoprecipitation experiments using E6 extracts demonstrated that the alpha 2 subunit was paired with the beta 1 integrin subunit. By E12, alpha 2 immunoreactivity in sections was confined to the extreme peripheral retina, although the antigen may be masked since expression levels comparable to or slightly higher than E6 could be detected in dissociated cells and extracts. By employing function blocking antibodies, it was shown that alpha 2 beta 1 integrin is necessary for cell adhesion and process outgrowth by embryonic retinal cells on collagens I and IV. Although alpha 2 expression continued through E12, alpha 2 activity was down regulated with increasing embryonic age, since alpha 2-dependent adhesion and outgrowth declined. These data suggest a role for alpha 2 beta 1 in neuroepithelial cell interactions with collagen rather than for axon extension by retinal ganglion cells.

Animals↗

PubMed1995

Glucose-induced alteration of integrin expression and function in cultured human mesangial cells.

Alteration in mesangial volume, due to an increase of the matrix surrounding mesangial cells, is a hallmark indicator of nephropathy in diabetes. Mesangial cells may also play a significant role in the development of nephropathy. Therefore, we examined the effect of glucose on the expression of integrins by cultured human mesangial cells and their ability to interact with collagen IV, a major component of the mesangial matrix. Human mesangial cells were grown in 5 and 25 mM glucose and their integrin profile was examined by immunoprecipitation and flow cytometry in each experimental condition. The results indicate that when mesangial cells were grown in 25 mM glucose, the expression of integrin subunit alpha 2, was increased, while the alpha 1 subunit was considerably decreased, as compared to cells grown in 5 mM glucose. Additionally, mesangial cells were tested for their ability to adhere to collagen IV in a solid-phase assay in the presence of neutralizing antibodies to integrin subunits. The results of these experiments indicate that both alpha 1 and alpha 2 complexed to beta 1 (alpha 2 beta 1 and alpha 1 beta 1) are major mesangial cell receptors for adhesion to collagen IV both in 5 and 25 mM glucose. The two receptors act in concert to mediate adhesion of mesangial cells to type IV collagen. When cell surface expression of the alpha 1 subunit in 25 mM glucose was reduced, the alpha 2 subunit was involved in adhesion to a greater extent than it was in 5 mM glucose. Immunoperoxidase histochemical studies localized both alpha 1 and alpha 2 integrin subunits in the mesangium of normal adult kidneys, suggesting that in vivo interaction with collagen IV could involve both of these receptors. These observations suggest that glucose-induced alterations in integrin expression may modify the ability of mesangial cells to interact with collagen IV.

Antibodies, Monoclonal↗

PubMed1994

Functional identification of integrin laminin receptors that mediate process outgrowth by human SY5Y neuroblastoma cells.

Treatment of the human neuroblastoma cell line SY5Y with nerve growth factor (NGF) induces terminal neuronal differentiation of a subpopulation of cells which can be selected by treatment with a DNA synthesis inhibitor. We have examined the interactions of naive (untreated) and NGF-differentiated SY5Y cells with laminin, and identified integrin receptors that mediate laminin-induced process outgrowth. Differentiated cells displayed a greater capacity for process extension, which correlated with increased expression of integrin laminin receptors. Both naive and differentiated cells expressed integrins alpha 1/beta 1, alpha 2/beta 1, and alpha 3/beta 1 but the differentiated population expressed about 5-fold higher levels of alpha 1/beta 1 and about 2-fold more alpha 2/beta 1 and alpha 3/beta 1 on their surface. Function blocking monoclonal antibodies were used to identify integrin receptors mediating process outgrowth. The anti-alpha 1 monoclonal antibody SR84 was shown to block alpha 1 function and inhibit process outgrowth on laminin. Despite the presence of multiple integrins which have been shown to bind laminin in other cell types, alpha 1/beta 1 mediated the majority of process outgrowth in both naive and differentiated cells, with a minor role played by alpha 3/beta 1. These data indicate that alpha 1/beta 1 function is required for process outgrowth on laminin by SY5Y cells and suggest that increased expression may be a crucial aspect of neuronal differentiation.

Antibodies, Monoclonal↗

PubMed1994

HLA-linked rheumatoid arthritis.

Twenty-eight pedigrees were ascertained through pairs of first-degree relatives diagnosed with rheumatoid arthritis (RA). RA was confirmed in 77 pedigree members including probands; the absence of disease was verified in an additional 261 pedigree members. Pedigree members were serologically typed for HLA. We used likelihood analysis to statistically characterize the HLA-linked RA susceptibility locus. The genetic model assumed tight linkage to HLA. The analysis supported the existence of an HLA-linked RA susceptibility locus, estimated the susceptibility allele frequency as 2.16%, and estimated the lifetime penetrance as 41% in male homozygotes and as 48% in female homozygotes. Inheritance was recessive in males and was nearly recessive in females. In addition, the analysis attributed 78% of the variance within genotypes to genetic or environmental effects shared by siblings. The genetic model inferred in this analysis is consistent with previous association, linkage, and familial aggregation studies of RA. The inferred HLA-linked RA susceptibility locus accounts for approximately one-half of familial RA, although it accounts for only approximately one-fifth of the RA in the population. Although other genes may account for the remaining familial RA, a large portion of RA cases may occur sporadically.

Adolescent↗

PubMed1994

Comparison of hydroxychloroquine and placebo in the treatment of the arthropathy of mild systemic lupus erythematosus.

OBJECTIVE: To compare the relative safety and efficacy of hydroxychloroquine (HCQ) and placebo (Pl) in the treatment of the articular complaints of systemic lupus erythematosus (SLE). METHODS: Seventy-one patients with mild SLE requiring < or = 10 mg of prednisone or equivalent daily and with arthritis or arthralgias were entered into a 48-week prospective, controlled, double blind multicenter trial and randomly assigned to either HCQ or Pl. RESULTS: Both HCQ and Pl were well tolerated in the 48-week trial. There were no remissions. With the exception of the patient assessment of joint pain, all other joint measures were similar between the groups. Twenty-nine patients withdrew before the end of the trial although only 2 patients withdrew for adverse drug effects. CONCLUSION: Our study found subjective pain relief as the only statistically significant difference in joint count variables from HCQ in the treatment of the articular manifestations of SLE.

Adult↗

PubMed1994

Comparison of aminobenzoate potassium and placebo in the treatment of scleroderma.

OBJECTIVE: To determine the safety and efficacy of aminobenzoate potassium (KPAB) in treating the skin manifestations of scleroderma. METHODS: Via a 48-week prospective, randomized, double blind, placebo controlled trial we compared the efficacy of KPAB 12 g/day with matching placebo. Outcome measures included skin mobility and thickening scores, patient and physician global assessments and, measurements of maximal oral aperture and hand range of motion. RESULTS: Of 146 patients who entered the study, 76 (52%) completed. Demographics of the study population included age 49 +/- 13 years, 83% women, mean (range) disease duration was 104 (7-600) months. There were no differences in the demographics of the KPAB vs placebo nor the group that completed the study compared with the withdrawal group. There were no clinical or statistically significant differences between the KPAB and the placebo treated groups in any of the outcome measures. Subgroup analyses of skin mobility and skin thickening based on age, extent of disease, severity of disease, duration of disease and involved vs uninvolved skin were performed, but no differences were noted. The overall compliance to the medical regimen was > or = 75% in 93% of patients completing the study. Eighteen patients in the KPAB group and 6 placebo patients withdrew due to adverse drug reactions (ADR). The most common withdrawals for ADR were gastrointestinal intolerance and headaches. All ADR resolved following withdrawal of medication. CONCLUSION: KPAB did not alter the skin changes of scleroderma in a group of patients with relatively longstanding stable disease. KPAB was reasonably well tolerated in this group of patients.

4-Aminobenzoic Acid↗

PubMed1993

Expression of the calsequestrin gene in chicken cerebellum Purkinje neurons.

Intracellular rapidly exchanging Ca2+ stores are identified and defined in terms of intralumenal low-affinity, high-capacity Ca(2+)-binding proteins, of which calsequestrin (CS) is the prototype in striated muscles. In chicken striated muscles, there is a single gene for CS [Choi and Clegg (1990) Dev. Biol. 142, 169-177]. In the chicken brain, the gene for CS was found to be selectively expressed in Purkinje neurons, as judged by Northern blotting, in situ hybridization and immunocytochemistry. The synthetic machinery for CS was found to be restricted to the cell body, i.e. excluded from dendrites and axon.

Animals↗

PubMed1993

Characterization of a beta-nerve growth factor expression vector for mammalian cells.

A mammalian expression vector that directs expression of murine beta-nerve growth factor (beta-NGF) from a murine sarcoma virus long terminal repeat (LTR) promoter element was constructed and characterized. The vector, designated pLTRSNGF, was stably transfected into murine L-cells, and beta-NGF mRNA and protein levels were quantified and compared to endogenous levels in control L-cells. Transfection of pLTRSNGF resulted in an approximate doubling of both beta-NGF mRNA and mature beta-NGF protein secreted into the media. Transfection of pLTRSNGF into rat PC 12 cells resulted in colonies of autocrine-differentiating cells that extended dense networks of neurites in the absence of added NGF, indicating that the beta-NGF produced from the vector is biologically active.

Animals↗

PubMed1993

Early undifferentiated connective tissue disease: III. Outcome and prognostic indicators in early scleroderma (systemic sclerosis).

OBJECTIVE: To characterize the course of early scleroderma and to delineate prognostic factors present within 1 year of disease onset that might identify patients at high risk. DESIGN: Inception cohort study. SETTING: Ten university-based rheumatology clinics participating in the Cooperative Systematic Studies of Rheumatic Diseases Program. PATIENTS: Forty-eight patients who had had scleroderma for less than 1 year. MEASUREMENTS: Fifteen patients with early scleroderma who died were compared with those still living during the initial study period (1982 to 1992). Kaplan-Meier survival estimation and Cox proportional hazards analysis were used to analyze baseline variables for their ability to predict survival duration. RESULTS: Eight of 15 deaths were due to cardiac or pulmonary system failure. The estimated 5-year survival rate was 68%. Baseline factors that were the most predictive of a poor outcome included the presence of abnormal cardiopulmonary signs and abnormal urine sediment (pyuria, hematuria). CONCLUSION: Evidence of early cardiopulmonary disease, renal disease, inflammation, or immune activation may identify a subset of patients with scleroderma who will experience rapidly progressive disease and early death.

Adult↗

PubMed1993

Comparison of naproxen and acetaminophen in a two-year study of treatment of osteoarthritis of the knee.

OBJECTIVE: To compare the relative safety and efficacy of naproxen and acetaminophen in the treatment of osteoarthritis (OA) of the knee. The major outcome measures were radiographic progression and withdrawal from the trial due to lack of efficacy. METHODS: One hundred seventy-eight patients with OA of the knee were enrolled in a 2-year prospective, controlled, double-blind multicenter trial and were randomly assigned to receive acetaminophen (ACT) or naproxen (NPX) treatment. RESULTS: After 6 weeks of treatment, modest improvement in pain on motion and in physician's global assessment was seen in both the ACT and the NPX groups, and the NPX group also had modest improvement in pain at rest and in 50-foot walk time. Sixty-two patients completed the 2-year study. Among these patients, radiographic progression was similar in the 2 treatment groups. Withdrawal from the trial due to lack of drug efficacy was slightly more frequent among patients in the ACT group (22% versus 16%), but withdrawal due to adverse drug effects was slightly more common in the NPX group (23% versus 18%). CONCLUSION: The efficacy of ACT treatment and NPX treatment was similar, although it was slightly better for NPX. The toxicity rate was slightly lower with ACT. However, the high rate of withdrawal in both treatment groups suggests that neither is satisfactory for the treatment of OA.

Acetaminophen↗

PubMed1993

The effect of long-term methotrexate therapy on hepatic fibrosis in rheumatoid arthritis.

OBJECTIVE: To evaluate the progression of hepatic fibrosis in patients with rheumatoid arthritis (RA) treated with methotrexate (MTX). METHODS: Fifteen patients receiving MTX for RA were prospectively studied by electron microscopic analysis of biopsy specimens. RESULTS: Five of the 15 patients had evidence of increased hepatic collagen after 2 years of MTX therapy. CONCLUSION: Hepatic fibrosis may progress in a subgroup of RA patients treated with MTX.

Arthritis, Rheumatoid↗

PubMed1992

Comparison of auranofin, methotrexate, and the combination of both in the treatment of rheumatoid arthritis. A controlled clinical trial.

OBJECTIVE: To compare the relative safety and efficacy of auranofin (AUR), methotrexate (MTX), and the combination of both in the treatment of active rheumatoid arthritis (RA). METHODS: Three hundred thirty-five patients with active RA were entered into a 48-week, prospective, controlled, double-blind, multicenter trial and were randomly assigned to 1 of 3 treatment groups. RESULTS: Two hundred eleven patients completed the trial. No remissions were seen, and there were no statistically significant differences among the treatment groups in the clinical or laboratory variables measured. Patients taking AUR alone had a slower onset of response than did patients taking MTX alone or in combination. Withdrawals because of adverse drug reactions were slightly more common for those taking combination therapy, but the differences were not statistically significant. Withdrawals because of lack of response were more common for single-drug therapy, with the difference between AUR and the combination reaching statistical significance. No unexpected adverse drug effects were identified, and all reactions resolved without sequelae. CONCLUSION: Except for fewer withdrawals because of lack of response, combination therapy did not demonstrate any advantage in efficacy over single-drug treatment within the time frame of the study.

Adolescent↗

PubMed1991

Evidence against a laminin receptor role for calsequestrin.

Calsequestrin, a muscle calcium binding protein, has been shown to bind the extracellular matrix protein laminin and evidence has been presented that CAL (initially called aspartactin) is on the cell surface, consistent with a role as a laminin receptor (1). In this report, we present evidence that does not support a laminin receptor function for CAL. We found that CAL immunoreactivity could not be detected on live cultured chick myotubes unless they were permeabilized with detergent. Furthermore, polyclonal anti-CAL antibodies did not perturb myotube adhesion to laminin or the rate of myoblast fusion on laminin. Expression of the CAL cDNA in a melanoma cell line that was poorly adherent to laminin did not increase adhesion to laminin. In these cells, CAL could not be detected on the cell surface, and the majority of CAL was found to be secreted into the media.

Animals↗

PubMed1991

Selective in vivo removal of rheumatoid factor by an extracorporeal treatment device in rheumatoid arthritis patients.

A prospective phase II trial was conducted to assess the feasibility, tolerance, and efficacy of a device designed for selective removal of rheumatoid factor from the plasma of rheumatoid arthritis patients. The device contained terpolymer hydrogel-coated plates with chemically attached, aggregated human immunoglobulin G, and it operated as an immunoaffinity column. Sixty-one patients aged 25 to 73 underwent weekly plasmapheresis treatments (the primary therapy phase). During the trial, patients continued current rheumatoid arthritis medications without dose adjustments. All patients received two to six treatments (primary therapy). Responding patients were eligible to continue apheresis treatment every 2 to 6 weeks (maintenance therapy). No serious, untoward side effects were noted in the course of this study; of 640 treatments, only 2 (in different patients) were aborted, one because of complaints of dizziness and angioedema and the other because of chest tightness and shortness of breath. Except for a significant (p less than 0.05) decrease in serum iron, no significant changes in complete blood count, serum electrolytes, renal and hepatic function tests, or serum C3 and C4 were noted. Although the trial was not designed to determine clinical efficacy, patients noted less morning stiffness, longer time to onset of fatigue, and improved global pain assessment (p less than 0.004); significant objective improvements were noted in joint pain, tenderness, swelling, and the number of affected joints (p less than 0.001). One-half of the treated patients had at least a 50 percent improvement in objective measures of antirheumatic activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Intracellular Ca2+ stores in chicken Purkinje neurons: differential distribution of the low affinity-high capacity Ca2+ binding protein, calsequestrin, of Ca2+ ATPase and of the ER lumenal protein, Bip.

To identify intracellular Ca2+ stores, we have mapped (by cryosection immunofluorescence and immunogold labeling) the distribution in the chicken cerebellar cortex of an essential component, the main low affinity-high capacity Ca2+ binding protein which in this tissue has been recently shown undistinguishable from muscle calsequestrin (Volpe, P., B. H. Alderson-Lang, L. Madeddu, E. Damiani, J. H. Collins, and A. Margreth. 1990. Neuron. 5:713-721). Appreciable levels of the protein were found exclusively within Purkinje neurons, distributed to the cell body, the axon, and the elaborate dendritic tree, with little labeling, however, of dendritic spines. At the EM level the protein displayed a dual localization: within the ER (rough- and smooth-surfaced cisternae, including the cisternal stacks recently shown [in the rat] to be highly enriched in receptors for inositol 1,4,5-triphosphate) and, over 10-fold more concentrated, within a population of moderately dense, membrane-bound small vacuoles and tubules, identified as calciosomes. These latter structures were widely distributed both in the cell body (approximately 1% of the cross-sectional area, particularly concentrated near the Golgi complex) and in the dendrites, up to the entrance of the spines. The distribution of calsequestrin was compared to those of another putative component of the Ca2+ stores, the membrane pump Ca2+ ATPase, and of the ER resident lumenal protein, Bip. Ca2+ ATPase was expressed by both calciosomes and regular ER cisternae, but excluded from cisternal stacks; Bip was abundant within the ER lumena (cisternae and stacks) and very low within calciosomes (average calsequestrin/Bip immunolabeling ratios were approximately 0.5 and 36.5 in the two types of structure, respectively). These results suggest that ER cisternal stacks do not represent independent Ca2+ stores, but operate coordinately with the adjacent, lumenally continuous ER cisternae. The ER and calciosomes could serve as rapidly exchanging Ca2+ stores, characterized however by different properties, in particular, by the greater Ca2+ accumulation potential of calciosomes. Hypotheses of calciosome biogenesis (directly from the ER or via the Golgi complex) are discussed.

Animals↗