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Biomedical subjects

A Parker

Publications and source records attributed to A Parker.

At least 109 records · Page 6Linked to original sources
PubMed1997

Synovial membrane inflammation and cytokine production in patients with early osteoarthritis.

OBJECTIVE: To establish the presence of inflammation in and cytokine production by synovial membranes from patients with various stages of early osteoarthritis (OA), with knee pain, normal knee radiographs, and arthroscopic evidence of chondral damage. METHODS: Synovial membrane samples were obtained from the knees of 63 patients at the time of arthroscopy for unexplained knee pain or at the time of joint replacement surgery. Evaluations of synovial membrane variables including thickness of lining layer, vascularity, and inflammatory cell infiltrate were by a blinded observer. In a subset of 20 patients, production of interleukin 1 alpha (IL-1 alpha), interleukin 1 beta (IL-1 beta), tumor necrosis factor alpha (TNF-alpha), and IL-1 receptor antagonist (IL-1ra) at the mRNA and protein levels was determined using in situ hybridization with biotin labeled ribo-probes and immunohistochemistry. RESULTS: There was evidence of thickening of the lining layer, increased vascularity, and inflammatory cell infiltration in synovial membranes from patients with all grades of OA, with the most marked changes seen in synovial tissue from patients with advanced grades of OA. Similarly, production of IL-1 alpha, IL-1 beta, and TNF-alpha was present in synovial membranes from all patients with OA, irrespective of the degree of articular cartilage damage. There was a trend to decreased levels of IL-1ra in synovial membranes from patients with OA that did not attain statistical significance. Similarly, there was a decrease in the ratio of IL-1ra to IL-1 alpha and beta with increasing grades of OA. CONCLUSION: Chronic inflammatory changes with production of proinflammatory cytokines are a feature of synovial membranes from patients with early OA, with the most severe changes seen in patients at the time of joint replacement surgery resembling those seen in rheumatoid arthritis. This low grade synovitis results in the production of cytokines that may contribute to the pathogenesis of OA.

Adolescent↗
PubMed1997

Synovial membrane cytokine profiles in reactive arthritis secondary to intravesical bacillus Calmette-Guérin therapy.

We describe the cellular infiltrate and cytokine profile in sequential synovial membrane biopsies from a patient with acute followed by chronic synovitis after intravesical bacillus Calmette-Guérin (BCG) therapy for an in situ transitional cell carcinoma of the bladder. Histological and immunohistochemical analysis of 3 synovial biopsies were done sequentially over a 9 month period. The patient was HLA-B27 positive, but HLA-DR4 negative, and did not have the "shared epitope." Unlike other cases, this patient's arthritis did not respond initially to nonsteroidal antiinflammatory drugs and was exacerbated by corticosteroid therapy. The synovitis took a neutrophilic form, with marked synovial membrane content of interleukin 8 (IL-8) and tumor necrosis factor alpha (TNF-alpha). It subsequently developed into chronic lymphoplasmacytoid synovitis, similar to rheumatoid arthritis (RA), with decreased IL-8 but continuing IL-1 and TNF-alpha production in the synovial membrane. The synovitis resolved to a fibrotic synovium with residual thickening of the synovial lining layer and continued production of TNF-alpha. Thus, during the evolution of this arthritis, the synovial layer and continued production of TNF-alpha. Thus, during the evolution of this arthritis, the synovial membrane yielded a cellular infiltrate and cytokine content that had marked similarities with that seen in RA; however, the arthritis eventually remitted spontaneously.

Aged↗
PubMed1997

Variability in cytokine and cell adhesion molecule staining in arthroscopic synovial biopsies: quantification using color video image analysis.

OBJECTIVE: To investigate the variability in immunostaining for cytokines and cell adhesion molecules using multiple arthroscopically directed synovial biopsies from within a rheumatoid knee joint, quantitated by color video image analysis. METHODS: Needle arthroscopic biopsies were taken from multiple sites (4-7 sites) around a knee joint in 8 patients with rheumatoid arthritis (RA). In 5 patients, immunoperoxidase staining for the cytokines tumor necrosis factor alpha (TNF-alpha), interleukin 8 (IL-8), and IL-1beta as well as the IL-1 receptor antagonist protein (IL-1ra) was performed. In 3 patients, immunoperoxidase staining for the cell adhesion molecules E-selectin (CD62E), P-selectin (CD62P), intercellular adhesion molecule 1 (ICAM-1, CD54), and platelet endothelial cell adhesion molecule (PECAM, CD31) was performed. Immunostaining was quantified using color video image analysis. RESULTS: The overall probability of paired biopsies from the same RA knee joint being significantly different from each other due to sampling variation was at most 22% for cytokine staining (usually less than 10%). There were no significant differences between intrabiopsy and interbiopsy variability for cell adhesion molecule staining of the sublining and vessels. CONCLUSION: The variability in cytokine and cell adhesion molecule staining within any single biopsy usually reflects the variability between biopsies taken from different sites in the same rheumatoid joint when the immunostaining is quantified using color video image analysis. Therefore, only a small number of synovial biopsies are required to accurately determine the cytokine and cell adhesion molecule expression in a single joint.

Aged↗
PubMed1997

High-throughput synthesis of functionalized oligonucleotides.

Functionalization of oligonucleotides with fluorescent dyes, biotin, and other reporter and capture labels is efficient, reliable, and convenient on the ABI 3948. The entire process of sequence entry, oligonucleotide synthesis, cleavage, deprotection, purification, quantitation, and sample collection is automated. Up to 48 oligonucleotides can be produced during unattended operation. The OneStep columns are filled with a mixture of nucleoside-loaded and underivatized, high-cross link, non-swelling polystyrene beads to conduct both synthesis and purification. Real-time, quantitative PCR, FRET hybridization, sequencing and genetic analysis experiments show the positive performance effects of the combined synthesis and purification of fluorescent dye-labelled primers and probes.

Automation↗
PubMed1996

Uncoupling of stem cell inhibition from monocyte chemoattraction in MIP-1alpha by mutagenesis of the proteoglycan binding site.

We have studied the role of proteoglycans in the function of Macrophage Inflammatory Protein-1 alpha (MIP-1alpha), a member of the proteoglycan binding chemokine family. Sequence and peptide analysis has identified a basic region within MIP-1alpha which appears to be the major determinant of proteoglycan binding and we have now produced a mutant of MIP-1alpha lacking the basic charges on two of the amino acids within this proteoglycan binding site. This mutant (Hep Mut) appears to have lost the ability to bind to proteoglycans. Bioassay of Hep Mut indicates that it has retained stem cell inhibitory properties but has a compromised activity as a monocyte chemoattractant, thus suggesting uncoupling of these two properties of MIP-1alpha. Receptor studies have indicated that the inactivity of Hep Mut on human monocytes correlates with its inability to bind to CCR1, a cloned human MIP-1alpha receptor. In addition, studies using proteoglycan deficient cells transfected with CCR1 have indicated that the proteoglycan binding site in MIP-1alpha is a site that is also involved in the docking of MIP-1alpha to the monocyte receptor. The site for interaction with the stem cell receptor must therefore be distinct, suggesting that MIP-1alpha utilizes different receptors for these two different biological processes.

Amino Acid Sequence↗
PubMed1996

Interaction of perirhinal cortex with the fornix-fimbria: memory for objects and "object-in-place" memory.

Four monkeys (Macaca mulatta) were trained preoperatively in an automated object-in-place memory task in which they learned 20 new scenes in each daily session. In the object-in-place memory task, the correct, rewarded response in each scene is to a particular object of a pair, which always occupies a particular position in a unique background that has been generated using randomly chosen colors and shapes. Each animal then underwent two surgeries, with a period of testing after each. In the first, control surgery, each animal had either a unilateral lesion of the perirhinal cortex or unilateral fornixfimbria transection, combined with section of the body and splenium of the corpus callosum and the anterior commissure (to prevent interhemispheric transfer of visual information). The disconnection was completed in the second surgery, after which all animals had a unilateral perirhinal cortex ablation in one hemisphere, unilateral fornix-fimbria transection in the contralateral hemisphere, and partial forebrain commissurotomy. The monkeys performance was compared for the learning of 200 scenes, preoperatively and after each surgery. After control surgery, the animals were mildly impaired on the object-in-place task. After disconnection, the animals showed a severe impairment in object-in-place memory. We conclude from this that, in episodic memory, the perirhinal cortex provides input of visual object information to the subiculum, hippocampus, and fornix.

Animals↗
PubMed1996

Identification of the extracellular matrix binding sites for insulin-like growth factor-binding protein 5.

Fibroblast extracellular matrix (ECM) contains two forms of insulin-like growth factor-binding proteins (IGFBPs), IGFBP-3 and IGFBP-5. These studies were undertaken to identify the regions within IGFBP-5 that mediate its binding to fibroblast ECM. Synthetic peptides were prepared that were homologous with two regions of basic amino acids within IGFBP-5 (Arg201-Arg218 and Ala131-Thr141). Increasing concentrations of both peptides competed with IGFBP-5 for binding to ECM but the Arg201-Arg218 peptide was more potent. Mutagenesis was used to define the effect of substituting for these basic residues on ECM binding. Substitution for two peptide B residues K134A and R136A reduced binding by 40%. Substitution of a single basic residue within the peptide A region (K211N) reduced binding to ECM by 49%. Substitution for K211N, K134A, and R136A reduced binding by 52%. More extensive substitutions in the peptide A region, e.g. K211N,R214A,K217A,R218N, resulted in a greater (e.g. 88%) decrease. The positional location of basic residues appeared to be more important than the total number of substitutions since the mutant K202N,K206A,R207A had a 79% reduction in ECM binding. Two basic regions of IGFBP-5 contribute to its binding to ECM, but the region containing amino acids 201-218 has a greater contribution. ECM binding is mediated by charged residues and acts to stabilize IGFBP-5 by protecting it from proteolysis.

Amino Acid Sequence↗
PubMed1996

Association between air pollution and acute childhood wheezy episodes: prospective observational study.

OBJECTIVE: To examine the association between the air pollutants ozone, sulphur dioxide, and nitrogen dioxide and the incidence of acute childhood wheezy episodes. DESIGN: Prospective observational study over one year. SETTING: District general hospital. SUBJECTS: 1025 children attending the accident and emergency department with acute wheezy episodes; 4285 children with other conditions as the control group. MAIN OUTCOME MEASURES: Daily incidence of acute wheezy episodes. RESULTS: After seasonal adjustment, day to day variations in daily average concentrations of ozone and sulphur dioxide were found to have significant associations with the incidence of acute wheezy episodes. The strongest association was with ozone, for which a non-linear U shaped relation was seen. In terms of the incidence rate ratio (1 at a mean 24 hour ozone concentration of 40 microg/m3 (SD=19.1)), children were more likely to attend when the concentration was two standard deviations below the mean (incidence rate ratio=3.01; 95% confidence interval 2.17 to 4.18) or two standard deviations above the mean (1.34; 1.09 to 1.66). Sulphur dioxide had a weaker log-linear relation with incidence (1.12; 1.05 to 1.19 for each standard deviation (14.1) increase in sulphur dioxide concentration). Further adjustment for temperature and wind speed did not significantly alter these associations. CONCLUSIONS: Independent of season, temperature, and wind speed, fluctuations in concentrations of atmospheric ozone and sulphur dioxide are strongly associated with patterns of attendance at accident and emergency departments for acute childhood wheezy episodes. A critical ozone concentration seems to exist in the atmosphere above or below which children are more likely to develop symptoms.

Acute Disease↗
PubMed1996

Substitution of specific amino acids in insulin-like growth factor (IGF) binding protein 5 alters heparin binding and its change in affinity for IGF-I response to heparin.

Heparin binding to insulin-like growth factor (IGF)-binding protein 5 (IGFBP-5) leads to a 17-fold decrease in its affinity for IGF-I, and a region that contains several basic amino acids (Arg201-Arg218) may be involved in this affinity shift. In the present study, mutagenesis was used to analyze the effect of substitutions for basic amino acids in the Arg201-Arg218 region of IGFBP-5 on heparin-binding and the heparin-induced affinity shift. Nine mutant forms were prepared. Their association constants (Ka) for IGF-I were similar to native IGFBP-5. When 10 microg/ml of heparin was added, the Ka of native IGFBP-5 decreased 17-fold, and the Ka of the K134A/R136A mutant decreased 16-fold. In contrast, substitutions for specific basic amino acids in the Arg2O1-Arg218 region decrease the affinity shift to 1.1-3.2-fold. Lys 211 was especially important. When a mutant containing that single substitution was tested, heparin caused only a 2.5-fold reduction in IGF-I affinity. Affinity cross-linking studies showed that heparin was equipotent in inhibiting the formation of 125I-IGF-I-K134A/Rl36A mutant complexes compared to native IGFBP-5. In contrast, heparin had minimal effects on the formation of complexes between 125I-IGF-I and the other mutants. The heparin-binding activity of each mutant was determined. Four mutants, R201A/K202N, K202A/K206A/R207A, R201A/K202N/K206N/K208N, and K211N/R214A/K217A/R218A, had reduced heparin binding compared to native IGFBP-5. The other five mutants, including the K21IN mutant, showed no change in heparin binding. The four mutants with reduced heparin binding could be dissociated from heparin-Sepharose with much lower NaCl concentrations, indicating that they had reduced affinity. These findings suggest that Arg201 Lys202, LysS206, and Arg214 are important for heparin binding. In contrast, LyS211 is not important for the binding of IGFBP-5 to heparin, but substitution for it reduced the heparin-induced affinity shift.

Affinity Labels↗
PubMed1996

Effects of pulse methylprednisolone on cell adhesion molecules in the synovial membrane in rheumatoid arthritis. Reduced E-selectin and intercellular adhesion molecule 1 expression.

OBJECTIVE: To investigate the effects of a 1,000-mg intravenous pulse of methylprednisolone succinate (MP) on cell adhesion molecule expression on the synovial vascular endothelium in patients with rheumatoid arthritis (RA). METHODS: Sequential arthroscopic biopsy samples were taken before and 24 hours after MP administration (10 patients) and at the time of RA flare (2 patients) and after retreatment with MP (1 patient). Immunoperoxidase staining for E-selectin (CD62E), P-selectin (CD62P), intercellular adhesion molecule 1 (ICAM-1; CD54) and platelet-endothelial cell adhesion molecule (PECAM; CD31) was performed, and the staining was quantified by color video image analysis. RESULTS: MP caused a rapid (within 24 hours) and substantial decrease in the expression of E-selectin on the synovial vascular endothelium, with a smaller reduction in ICAM-1 expression on synovial vascular endothelium and the synovial lining. There were no similar effects on synovial membrane P-selectin or PECAM expression. CONCLUSION: A potential mechanism by which MP impairs neutrophil trafficking into inflamed RA joints might be by reducing E-selectin, and possibly, ICAM-1, expression in the synovial membrane.

Aged↗
PubMed1996

An improved amplification and sequencing strategy for phylogenetic studies using the mitochondrial large subunit rRNA gene.

Numerous molecular systematic studies have employed variation in the mitochondrial large subunit (16s) rRNA gene to infer patterns of relationship among species and higher taxa. The primers most commonly employed in 16s rRNA amplification and sequencing bracket an approximately 600 bp portion of this gene. However, most of the informative variation occurs within a 200 bp subset of this segment. We describe a novel primer pair designed to amplify this variable region in a wide range of taxa, allowing broader application and considerable streamlining of data acquisition for studies using this gene.

Animals↗
PubMed1996

Interdecadal heterogeneity in mitochondrial DNA of Atlantic haddock (Melanogrammus aeglefinus) from Georges Bank.

Atlantic haddock of Georges Bank are characterized by large fluctuations in population size and a recent collapse of the commercial fishery. DNA extracted from dried scales of Georges Bank haddock, archived by the U.S. National Marine Fisheries Service (NMFS), reveals significant heterogeneity in frequencies of four mitochondrial DNA control region haplotypes between 1975 and 1985 cohorts. Several processes may be responsible for this temporal variation, the most attractive hypothesis being that haddock from other geographic regions episodically contribute to the Georges Bank gene pool. Thus, the population of haddock spawning on Georges Bank may not be genetically discrete and, with respect to Atlantic haddock, Georges Bank may not be viewed as a closed system.

Animals↗
PubMed1995

Olfactory-visual associative learning in monkeys depends on intrahemispheric olfactory-visual interaction.

Three Cynomolgus monkeys (Macaca fasicularis) learned a series of food-visual conditional discrimination problems. In each problem, 1 of 2 possible food items was presented at the beginning of each trial and acted as an instruction cue as to which of 2 visually distinct stimulus objects the monkey must displace on that trial to obtain a further food reward. Following surgical disconnection of olfactory-visual intrahemispheric interaction, the monkeys were unable to use olfactory properties of the food items to guide visual choices. These results show both that olfactory differences between foodstuffs are a powerful olfactory stimulus, which can enter into cross-modal association with visual stimuli, and that this association depends on an intrahemispheric pathway of olfactory-visual interaction.

Afferent Pathways↗
PubMed1995

Properties of an insulin-like growth factor-binding protein-4 protease that is secreted by smooth muscle cells.

Smooth muscle cells (SMC) secrete insulin-like growth factor (IGF)-binding protein-4 (IGFBP-4) and an IGFBP-4 protease. The purpose of this study was to determine the characteristics of this IGFBP-4 protease and to compare its inhibitor profile to those of IGFBP-5 and IGFBP-2 proteases, which are also present in SMC-conditioned medium. Cultured SMC were exposed to serum-free medium for periods of 24-72 h, and the amount of proteolytic activity in the conditioned medium was assessed by its capacity to degrade pure IGFBP-4. Minimal activity (e.g. < 20% of IGFBP-4 degraded in 24 h at 37 C) was present in conditioned medium unless IGF-I or IGF-II was added. This resulted in more than 60% of the intact IGFBP-4 being degraded in 14 h. The activity was a calcium-dependent serine protease and was inhibited by EDTA or 3,4-dicloroisocoumarin. Calcium, but not zinc, could restore proteolytic activity. Heparin alone inhibited IGFBP-4 proteolysis by more than 60%. When heparin cofactor-II and antithrombin-III (AT-III) were added alone, they each had an effect. The combination of heparin plus AT-III was no more active than heparin alone, but the combination of heparin cofactor-II and heparin resulted in near complete inhibition. Peptides that contained the active sites of AT-III or alpha 1-antichymotrypsin were potent inhibitors of the IGFBP-4 protease. The medium also contained proteolytic activities for IGFBP-2 and IGFBP-5. Comparison of the inhibitor profiles for the IGFBP-4 and IGFBP-5 proteolytic activities revealed major differences, but the IGFBP-2 proteolytic activity was very similar to that of the IGFBP-4 protease. IGFBP-4 zymography showed a band with a molecular mass estimate of 48 kilodaltons. In contrast, when IGFBP-2 was used as the substrate, a single band at 36 kilodaltons was visualized. These data taken together with the protease inhibitor results suggest that the IGFBP-2, IGFBP-4, and IGFBP-5 proteases are members of a similar family of calcium-dependent serine proteases, but they are distinct proteases. As IGFBP-4 is a potent inhibitor of IGF action, and the activity of this protease is regulated by IGF exposure, the protease represents a novel system for regulating the actions of IGF-I in this cell type.

Animals↗
PubMed1994

Heparin, heparan sulfate, and dermatan sulfate regulate formation of the insulin-like growth factor-I and insulin-like growth factor-binding protein complexes.

The mechanisms by which insulin-like growth factor-I (IGF-I) is released from insulin-like growth factor binding proteins (IGFBPs) and then binds to its receptor have not been defined. This study was designed to determine the role of glycosaminoglycans in altering the formation of the IGF-I.IGFBP complexes. Heparin inhibited formation of the IGF-I.IGFBP-5 complex and also separated preformed IGF-I.IGFBP-5 complexes. Heparin also inhibited formation of the IGF-I.IGFBP-3 complex; however, it did not inhibit formation of complexes between IGF-I and IGFBP-1, -2, or -4. Heparin exposure was associated with a 17-fold decrease in the affinity of IGFBP-5 for IGF-I. A synthetic peptide that contains residues from Arg221 to Arg238 of IGFBP-5, and a heparin binding domain prevented the inhibitory effects of heparin on formation of the IGF-I.IGFBP-5 complex. It did not directly compete with IGF-I for binding to IGFBP-5, suggesting that heparin binding to this region of IGFBP-5 resulted in a conformational change in IGFBP-5 which lowered its affinity for IGF-I. Other glycosaminoglycans that contained O-linked sulfates in the 2 or 3 carbon positions of iduronic acid, e.g. heparan sulfate and dermatan sulfate, also inhibited the IGF-I.IGFBP-5 complex formation, whereas those that did not, such as keratan sulfate or hyaluronic acid, had minimal effects. Anionic polysaccharides that contained O-sulfate groups in the 2 or 3 positions, such as dextran sulfate, pentosan polysulfate, and fucoidan, also had inhibitory activity. The findings suggest a role for these compounds in inhibiting IGF-I.IGFBP interactions, thus making IGF-I available to bind to its receptor.

Amino Acid Sequence↗
PubMed1994

Cytomegalovirus in upper gastrointestinal ulcers.

Cytomegalovirus (CMV), an important cause of severe infections in immunocompromised patients, can cause ulcerations anywhere in the gastrointestinal tract, most commonly stomach and colon. Only a few cases of CMV inclusions in gastrointestinal ulcers have been reported in normal hosts. We undertook a prospective study of the incidence of CMV in gastroduodenal ulcerations in immunocompetent patients. Thirty-eight patients who were referred for evaluation of dyspepsia, hematemesis, melena, guaiac-positive stools, or iron deficiency anemia and who had gastric or duodenal ulcerations without stigmata of recent hemorrhage or visible vessel were enrolled in the study. Six biopsies obtained from the ulcer base and margin were submitted for histologic examination, shell-vial viral cultures, and monoclonal antibody testing. Thirty-two patients had gastric ulcer and six had duodenal bulbar ulcer ranging in size from 8 to 20 mm in diameter. Forty-four percent of patients had been taking aspirin or nonsteroidal antiinflammatory drugs (NSAIDs) within 10 days of ulcer discovery. Evaluation of all biopsies in 38 patients failed to document any evidence of CMV by light microscopy, viral cultures, or monoclonal antibody testing. CMV infection is uncommon in the gastrointestinal tract of immunocompetent patients with gastroduodenal ulcers. Even within areas of previous mucosal injury induced by nonsteroidal drugs, no evidence of CMV "superinfection" was found. We conclude that CMV infection is not a significant factor in routine peptic or NSAID-induced ulcer disease, and the discovery of CMV inclusions in gastroduodenal ulcerations should lead to a search for an immunocompromised state.

Adult↗