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J C Moore

Publications and source records attributed to J C Moore.

At least 55 records · Page 3Linked to original sources
PubMed1995

A role for microfilaments but not microtubules in processing soluble antigens.

Ag processing involves multiple intracellular membrane transport events required for delivery of Ag to degradative compartments in the endocytic pathway of antigen-presenting cells (APC) and transport of newly synthesized class II MHC proteins to compartments where peptide loading occurs. Movement and distribution of various subcellular vesicles have been shown to involve elements of the cytoskeletal network. We have examined the role of microtubules and microfilaments in Ag processing and presentation by B lymphoblastoid cells. Experiments with nocodazole or colchicine, drugs that disrupt the microtubule network, demonstrate that intact microtubules are not required for efficient processing of soluble Ag in these cells. Cytochalasins, which disrupt actin microfilaments, are observed to partially inhibit processing of soluble Ag. Inhibition is reversible and dependent on both the dose of drug and length of exposure. Control experiments demonstrate that the effect does not result from drug toxicity or decreased Ag uptake. Treatment of APC with cytochalasin B does not block delivery of internalized protein to dense lysosomes. However, the ability of the cells to catabolize internalized protein is partially inhibited. Our results suggest that microfilament-dependent, but not microtubule-dependent, vesicular transport may be required for efficient Ag processing in B lymphoblastoid cells.

Actin Cytoskeleton↗
PubMed1994

Membrane interactions influence the peptide binding behavior of DR1.

We analyzed the binding of an influenza matrix protein-derived peptide, MAT(17-31), to cell surface and purified DR1. The pH dependence of peptide binding was dramatically influenced by the membrane environment. Cell surface binding was enhanced at low pH, with little or no binding detected at neutral pH and optimal binding at pH 4. By contrast, hydrogen ion concentration had minimal effect on peptide binding to purified DR1. Exposure to low pH in the absence of peptide did not affect the peptide binding capacity of cell-associated DR1. Purified DR1 was stable at low pH, excluding the possibility that enhanced binding was offset by a competing denaturation event at low pH. The striking effect of pH on peptide binding characteristic of cell surface DR1 was recovered after reconstitution of purified DR1 in B cell membranes by detergent dialysis. This behavior was partially recovered by reconstitution of full-length, but not truncated DR1 in vesicles containing purified lipid. Our results demonstrate that interactions involving membrane components influence the peptide-binding behavior of DR1.

Amino Acid Sequence↗
PubMed1994

Requirement for protein synthesis in antigen processing by B cells.

The role de novo protein synthesis plays in Ag processing by B cells was investigated. Cycloheximide (CHX) inhibited Ag processing in normal and transformed B cells. B lymphoblastoid cells required a 2-6 hr longer CHX pretreatment period than splenic B cells to inhibit Ag processing function. Immunoprecipitation experiments demonstrated that the half-life of class II/invariant chain (Ii) complexes was similar in normal and transformed B cells. B lymphoblastoid cells differed from splenic B cells in that a significant fraction of total class II-associated p31 Ii was modified with sialic acid (Ip). The kinetics of loss of class II-associated Ip in CHX-treated cells correlated with loss of Ag processing function. In addition, the half-life of a subpopulation of class II molecules that are unstable in sodium dodecyl sulfate at room temperature was greater in transformed cells. Our results suggest that B lymphoblastoid cells, but not splenic B cells, contain a long-lived pool of class II/Ii complexes that can bind and present peptides generated in endosomal compartments for a significant time period after cessation of protein synthesis.

Animals↗
PubMed1993

A europium fluoroimmunoassay for measuring binding of antigen to class II MHC glycoproteins.

A dissociation-enhanced lanthanide fluoroimmunoassay employing europium-streptavidin and time-resolved fluorimetry was developed to measure binding of biotin-labeled peptides to class II MHC proteins. Binding of biotin-peptides as measured by this assay was saturable and inhibited in the presence of unlabeled peptide. Background fluorescence was minimal and there was a direct relationship between signal and biotin-peptide/class II complex concentration from 1.3 pmol to less than 1 fmol total class II. The sensitivity of the assay and the ability to selectively capture specific class II proteins from detergent lysates of cells with solid phase mAb made it possible to measure formation peptide/class II complexes in live APC cultured with biotin-labeled insulin. This assay is expected to be useful for routine measurement of peptide/class II binding and biochemical analysis of Ag processing events.

Amino Acid Sequence↗
PubMed1993

Surface ultrastructure of human dermis and wounds.

Scanning electron microscopic observations of the de-epidermalized surfaces of wounds and control skin reveal the architecture of dermal collagen. At wound edges there is a transition from the normal regular rete peg structure through erratically shaped finger-like projections with buds, to the relatively flat surface of granulation tissue. A corresponding change in the ultrastructure of dermal collagen is seen from normal areas where bundles of thick fibres are made up from finer fibrils, through a transitional zone where only fine fibrils are visible, to the granulation tissue where a disorganised amorphous structure is seen. It is suggested that the fibrous tissue surface at the edges of healing wounds is extensively remodelled after it is covered by epidermal cells.

Basement Membrane↗
PubMed1993

Assessment of disturbance on soil ecosystems.

Given the complexity of ecosystems, the high degree of interactions among species, and the numerous responses of systems to disturbance, it is unlikely that simple assays developed for other systems would adequately serve to monitor soil systems. Apart from the questionable applicability of non-soil techniques, protocols to monitor soil biota in a standardized manner have not been developed. To monitor soils, a five-phase plan is proposed. The plan involves: (1) a thorough survey of the systems biota; (2) laboratory toxicity trials on indicator species (Folsomia candida); (3) field tests on indicator processes (litter decomposition); (4) field monitoring of indicator functional groups (nematodes); (5) the development of standardized statistical techniques and simulation models. Each phase of the plan was designed to capture a different aspect of food web structure and function.

Animals↗
PubMed1993

Soil invertebrate/micro-invertebrate interactions: disproportionate effects of species on food web structure and function.

The preservation of biodiversity requires an appreciation of food web structure and an understanding of how disturbance alters their structure and function. Theoretical and empirical studies of food webs demonstrate that food webs possess a regular structure. Food chain length appears limited to three to four transfers, and, complexity and diversity are constrained. When ecosystem energetics are considered, species within food webs are seen to form interactive assemblages that process matter at different rates and respond to disturbance differently. Disturbance may affect the diversity of a system, or, may influence the relative importance of one species assemblage over another. Moreover, predicting the impact of disturbance on a system is difficult as species that comprise and process a small fraction of the system's biomass may control a disproportionate fraction of the system's biomass and diversity. Seven food webs at four sites were used in a modeling exercise to demonstrate this point. Field studies involving the role of mycorrhizal fungi yielded results consistent with the modeling studies as the types of plant species present, the level of production and the diversity of production were related to the levels of mycorrhizal fungi in the soils following disturbance. The results indicate that all species are important to ecosystem structure and function and that the monitoring of ecosystems and conservation efforts should expand their emphasis to the preservation of ecosystem integrity as well as that of individual species.

Animals↗
PubMed1993

Factors affecting tooth movement in sliding mechanics.

The force system operating between bracket and wire in sliding mechanics has been examined analytically using simple beam theory with the object of providing further information on the cause of bracket binding. The results were checked on an enlarged model system, and satisfactory agreement between experiment and theory was obtained. It is shown that for a given bracket tip the restoring couple varies not only with the flexural rigidity (EI) of the wire, the bracket width and span length, but also with the position of the bracket along the span. In addition, as tipping occurs a net vertical force is brought into play which is initially intrusive, but becomes extrusive as retraction proceeds.

Elasticity↗
PubMed1993

Downwind drift and deposition of malathion on human targets from ground ultra-low volume mosquito sprays.

Malathion was sprayed using a truck-mounted ultra-low volume (ULV) aerosol generator. The generator was operated at 41.4 kPa (6 psi) at flow rate of 128 ml (4.3 fl. oz.) per min. Malathion concentrations were measured at selected positions on live, stationary human subjects wearing protective clothing and placed along a transect at right angles to the path of the truck. Two standing subjects were exposed downwind to the malathion spray at 7.6 and 15.2 m. A third subject was exposed while jogging in the same direction as the spray vehicle and 1.5 m from the spray path. No significant differences (P > 0.05) in total amount of malathion deposited on subjects was demonstrated. During the last 4 sprays, average amounts of malathion deposited on ground level at 15.2, 30.4 and 91.2 m were not significantly different (P > 0.05). Malathion dermal residues were compared with the acute LD50 value (4,100 mg/kg) for a 70 kg adult male. Calculated malathion dermal exposures were less than the acute lethal dose for a human subject by 4 orders-of-magnitude or more.

Adult↗
PubMed1992

Calpain activity in patients with thrombotic thrombocytopenic purpura is associated with platelet microparticles.

Thrombotic thrombocytopenic purpura (TTP) is characterized by thrombocytopenia and disseminated platelet thrombi throughout the microvasculature. Studies by our group have demonstrated calcium-dependent proteolytic activity (calpain) that is no longer detectable in the serum of patients with acute TTP after their recovery. The purpose of this study was to investigate if the protease activity of TTP was detectable in plasma and, therefore, not an in vitro phenomenon secondary to the formation of serum. Additionally, we looked for evidence of membrane association of the active protease in the patients' samples, which would explain the persistence of its activity in the presence of plasma inhibitors. Acute TTP samples, both serum and plasma, were collected from 10 patients with TTP. Calpain was measured using bioassays for enzyme activity and also by detection of the protein using immunoblotting with an anticalpain monoclonal antibody (MoAb). In all instances, calpain could be detected both functionally and antigenically in the acute TTP sera and plasma. No calpain activity could be detected in any of the controls, although antigenic calpain was detectable in one sample from a patient who had undergone cardiopulmonary bypass surgery. To investigate whether the calpain was associated with microparticles in the plasma, the TTP plasma samples were ultrafiltered and ultracentrifuged. Activity was not lost by passage across a 0.2-micron filter but was detectable only in the pellet following ultracentrifugation. Membrane association of the calpain in the microparticles also was demonstrated using solubilization with Triton X-100. Immunoprecipitation studies demonstrated that the calpain activity could be removed by MoAbs against platelet membrane glycoproteins (IX and IIb/IIa) but not by a MoAb against red blood cell membrane glycophorin. These studies indicate that active calpain is associated with platelet microparticles in plasma from patients with TTP.

Blood Platelets↗
PubMed1992

Aortic stenosis and bleeding gastrointestinal angiodysplasia: is acquired von Willebrand's disease the link?

An association between aortic stenosis and haemorrhage from gastrointestinal angiodysplasia has been recognised for many years, but no explanation for this link has been found. Remarkably, aortic valve replacement, rather than bowel resection, corrects the bleeding. Aortic stenosis can be complicated by acquired von Willebrand's disease type IIA (vWD-IIA), which is corrected after valve replacement, and gastrointestinal angiodysplasia is a common site of bleeding in older patients with acquired or congenital vWD. Could the stenotic aortic valve lead to an acquired, reversible deficiency of the largest multimers of plasma von Willebrand factor (equivalent to vWD-IIA) and thus explain the association with gastrointestinal haemorrhage?

Angiodysplasia↗
PubMed1992

Thrombotic thrombocytopenic purpura.

Thrombotic thrombocytopenic purpura is an uncommon disorder, but it continues to be of considerable interest. The disease mechanisms are unclear and the aetiology is unknown. Perhaps most enigmatic of all, the mode of action of plasma therapy, which successfully induces remission in about two-thirds of cases, is wholly inexplicable. There are currently several areas of debate on the subject of thrombotic thrombocytopenic purpura. This paper addresses these points of contention: the definition of the disease, its distinction from haemolytic uraemic syndrome, the nature of the platelet aggregating factors in the plasma of patients with acute disease, the importance of the abnormalities of von Willebrand's factor observed in the acute and quiescent phases of the disease, the nature of the factor in normal plasma that induces remission, and the possible causes of the observed superiority of plasma exchange combined with plasma infusion, over plasma infusion alone.

Calpain↗
PubMed1990

Craniofacial osseous restoration with osteoinductive proteins in a collagenous delivery system.

Implants fabricated from mixtures of extracted bovine bone proteins and highly purified human type I collagen have been tested for efficacy in the restoration of osseous defects. Experimental implants composed of osteoinductive proteins and collagen, and control implants composed of collagen alone were placed in 15 x 15 mm cranial defects in New Zealand white rabbits. Implants harvested at 10, 12 and 14 week intervals were subjected to histological evaluation as well as quantitative analysis utilizing a computer morphometric planimeter. Defects filled with control implants displayed highly variable repair with a mean of 31% bony healing. Experimental implants were consistently effective in inducing significant bony regeneration with a mean of 91% repair within the time range of the study. In light of these results, it is apparent that an osteoinductive-collagenous implant system represents an efficacious treatment modality in osseous reconstruction and augmentation.

Animals↗
PubMed1990

Calpain proteolysis of von Willebrand factor enhances its binding to platelet membrane glycoprotein IIb/IIIa: an explanation for platelet aggregation in thrombotic thrombocytopenic purpura.

We have previously observed calpain activity (calcium-dependent cysteine protease) in sera from patients with acute thrombotic thrombocytopenic purpura (TTP). The calpain activity was not present following recovery and was not detected in other thrombocytopenic disorders. We postulated that this enzyme could participate in the pathogenesis of TTP. Because other investigators have demonstrated abnormalities of von Willebrand factor (vWF) in patients with TTP, we proposed that calpain might interact with vWF in TTP. To challenge this hypothesis, we measured the binding of untreated and calpain-treated vWF to normal and ADP or calpain activated platelets. Untreated vWF bound in a specific and saturable fashion to activated platelets, but only at low (30 microM) calcium concentrations. Von Willebrand factor did not bind to activated platelets at physiological (2 mM) calcium concentrations. Calpain proteolysis of vWF changed the binding characteristics of the vWF so that it had greatly increased binding to both ADP and calpain activated platelets. The calpain-proteolyzed vWF bound to activated platelets at both low and physiological calcium concentrations, and was capable of causing platelet aggregation. The calpain-proteolyzed vWF bound to the activated platelets via glycoproteins IIb/IIIa as demonstrated by inhibition studies using monoclonal antibodies against glycoproteins IIb/IIIa and Ib. It also had a high binding affinity and was capable of inhibiting the binding of radiolabelled fibrinogen to the activated platelets at physiological calcium concentrations. Calpain also proteolyzed fibrinogen, but the calpain altered fibrinogen had normal platelet reactivity. These studies provide further insight into the pathogenesis of the platelet aggregation of thrombotic thrombocytopenic purpura. Calpain proteolyses vWF and can produce the characteristic loss of large multimers seen on sodium dodecyl sulphate (SDS)-agarose gel electrophoresis. The altered vWF is highly reactive with activated platelets and binds to platelet glycoproteins IIb/IIIa and participates in formation of the platelet aggregates that characterize this disease.

Binding, Competitive↗
PubMed1990

The platelet aggregating factor(s) of thrombotic thrombocytopenic purpura.

Thrombotic thrombocytopenic purpura is characterized by disseminated platelet aggregates throughout the microcirculation and a large body of clinical, experimental and pathological evidence implicates in vivo platelet aggregation as being pivotal in the disease. For this reason considerable energy has been spent by many investigators to identify a platelet aggregating factor. The understated reason for these studies is that the characterization of such a factor could lead to the subsequent identification of a medication or a plasma factor that could neutralize the aggregating factor. Although a platelet aggregating factor has been suspected to play a causal role in TTP for almost 50 years, only in recent years have investigators systematically attempted to identify such a factor. One group has identified a 37 kD protein in the plasma of TTP patients which can initiate platelet aggregation through a unique pathway of aggregation and this factor can be inhibited by normal IgG. The other group of workers (ourselves) have provided evidence that the platelet aggregating factor of TTP is calpain. Thus, the very nature of the aggregating factor, and by implication its inhibitors, is very different for the two groups, and it may take other investigators to resolve whether there are multiple platelet aggregating factors of TTP. Nonetheless, it is apparent that recent research has dramatically improved our understanding of this uncommon but important disorder and it is possible that such investigations will lead to more successful treatments of this condition.

Blood Coagulation Factors↗
PubMed1989

Changes in red nucleus neuronal development following maternal alcohol exposure.

The red nucleus of Swiss Webster mouse fetuses was examined for morphological changes following maternal ethanol exposure. Pregnant females were given a liquid diet containing 30% or 0% ethanol-derived calories. Changes in numerical density of neurons and in neuronal nuclear volume were found in the rostral red (RR) nucleus of ethanol-exposed pups but not in the caudal red (CR) nucleus. Because of the integrative nature of the RR, changes in neuronal morphology that might relate to synaptic connections could affect the behavioral response mechanisms of these offspring.

Animals↗