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C L Harris

Publications and source records attributed to C L Harris.

At least 19 recordsLinked to original sources
PubMed2002

Tailoring anti-complement therapeutics.

Complement is a core component of the immune system, which performs vital roles in immune surveillance. However, the active products that enable complement to perform its physiological roles can inappropriately target self tissues and cause pathology. Complement-mediated inflammation and tissue destruction is an important drive to pathology in diseases as diverse as rheumatoid arthritis and dementia. Two decades ago there were no agents that could be used therapeutically to inhibit the activation of complement, but increased understanding of the natural control of complement in vivo has markedly changed this situation. The realization that drugs mimicking the action of the complement regulatory proteins present on self cells, and in plasma, could effectively control pathological activation of complement has opened the door to the use of anticomplement therapy in disease. Here we will review the development of anticomplement therapeutics from the first generation agents, which are unmodified recombinant forms of natural regulators, to recent strategies for making better drugs. We will describe strategies for targeting the anticomplement activity to the site of disease, and for extending the plasma half-life of the agent. Finally, we will illustrate a novel approach to the delivery of anticomplement agents, making prodrugs that are activated only at disease sites thus minimizing the deleterious effects of systemic complement inhibition.

Animals↗
PubMed2002

Coupling complement regulators to immunoglobulin domains generates effective anti-complement reagents with extended half-life in vivo.

Complement activation and subsequent generation of inflammatory molecules and membrane attack complex contributes to the pathology of a number of inflammatory and degenerative diseases, including arthritis, glomerulonephritis and demyelination. Agents that specifically inhibit complement activation might prove beneficial in the treatment of these diseases. Soluble recombinant forms of the naturally occurring membrane complement regulatory proteins (CRP) have been exploited for this purpose. We have undertaken to design better therapeutics based on CRP. Here we describe the generation of soluble, recombinant CRP comprising rat decay accelerating factor (DAF) or rat CD59 expressed as Fc fusion proteins, antibody-like molecules comprising two CRP moieties in place of the antibody Fab arms (CRP-Ig). Reagents bearing DAF on each arm (DAF-Ig), CD59 on each arm (CD59-Ig) and a hybrid reagent containing both DAF and CD59 were generated. All three reagents inhibited C activation in vitro. Compared with soluble CRP lacking Fc domains, activity was reduced, but was fully restored by enzymatic release of the regulator from the Ig moiety, implicating steric constraints in reducing functional activity. In vivo studies showed that DAF-Ig, when compared to soluble DAF, had a much extended half-life in the circulation in rats and concomitantly caused a sustained reduction in plasma complement activity. When given intra-articularly to rats in a model of arthritis, DAF-Ig significantly reduced severity of disease. The data demonstrate the potential of CRP-Ig as reagents for sustained therapy of inflammatory disorders, including arthritis, but emphasize the need for careful design of fusion proteins to retain function.

Animals↗
PubMed2001

PIG-M transfers the first mannose to glycosylphosphatidylinositol on the lumenal side of the ER.

Glycosylphosphatidylinositol (GPI) acts as a membrane anchor of many cell surface proteins. Its structure and biosynthetic pathway are generally conserved among eukaryotic organisms, with a number of differences. In particular, mammalian and protozoan mannosyltransferases needed for addition of the first mannose (GPI-MT-I) have different substrate specificities and are targets of species- specific inhibitors of GPI biosynthesis. GPI-MT-I, however, has not been molecularly characterized. Characterization of GPI-MT-I would also help to clarify the topology of GPI biosynthesis. Here, we report a human cell line defective in GPI-MT-I and the gene responsible, PIG-M. PIG-M encodes a new type of mannosyltransferase of 423 amino acids, bearing multiple transmembrane domains. PIG-M has a functionally important DXD motif, a characteristic of many glycosyltransferases, within a domain facing the lumen of the endoplasmic reticulum (ER), indicating that transfer of the first mannose to GPI occurs on the lumenal side of the ER membrane.

Amino Acid Sequence↗
PubMed2001

Identity and similarity in repetition blindness: no cross-over interaction.

The difficulty in reporting both occurrences of a repeated item is a phenomenon referred to as repetition blindness (RB). RB has been proposed to result from temporal limitations in creating separate episodic tokens for a twice-activated type. Recently, Chialant and Caramazza (Cognition 63 (1997) 79-119) disputed the conventional view that RB for non-identical words (orthographic RB, as in lice and lick) results from the same mechanism as identity RB, and proposed that orthographic RB arises from competition for lexical selection. Supporting evidence was that identical and merely similar words showed different amounts of RB as a function of stimulus onset asynchrony (lag). Four experiments failed to replicate Chialant and Caramazza's finding that identity RB decreases, but orthographic RB increases, as a function of lag. Instead, RB for all stimuli, including homonym pairs, declined monotonically with lag. These results are consistent with a common mechanism underlying RB for identical and orthographically similar words and with prior research suggesting that RB in similar words occurs at a sublexical level.

Adult↗
PubMed2001

Enhancement of complement-mediated lysis by a peptide derived from SCR 13 of complement factor H.

Complement factor H (fH) is an important regulator of complement activation. It contributes to protection of cells against homologous complement attack. In this study we tested the effect of fH-depletion of normal human serum (NHS) on lysis of antibody-coated sheep and human erythrocytes (EshA and EhuA). In the absence of fH, lysis of sensitised Esh and Ehu was clearly increased. Addition of fH to fH-depleted serum re-established protection of cells against complement similar to that seen with NHS. A fH-derived peptide (pepAred), covering the N-terminal half of SCR 13 in fH, was able to enhance complement-mediated lysis of EhuA significantly. However, the oxidised form of this peptide (pepAox) had no effect. Biotinylated pepAred, but not pepAox, was able to directly bind to cells. Additionally, pepAred competed with direct fH-cell interaction which was observable only after treatment of purified fH with mercaptoethanol. Only pepAred increased the amount of C3 fragments and reduced levels of fH detectable on cells as shown by FACS analysis and radio-immuno assay. Furthermore, fH and factor I (fI)-mediated cleavage of agarose bound C3b into iC3b was decreased in the presence of pepAred. These data indicate that a fH-derived peptide can enhance complement-mediated lysis. We will continue to investigate whether the use of a fH peptide can be exploited for therapeutical purposes.

Amino Acid Sequence↗
PubMed2001

Characterization of glycosylphosphatidylinositol-anchored decay accelerating factor (GPI-DAF) and transmembrane DAF gene expression in wild-type and GPI-DAF gene knockout mice using polyclonal and monoclonal antibodies with dual or single specificity.

Decay-accelerating factor (DAF, CD55) is a glycosylphosphatidylinositol (GPI)-linked membrane inhibitor of complement activation. While human and other mammalian species contain only one DAF gene, two distinct DAF genes, referred to as GPI-DAF and transmembrane (TM)-DAF, respectively, have been identified in the mouse. Using several independently generated monoclonal and polyclonal antibodies, either with dual or single specificity for GPI-DAF and TM-DAF gene products, we have examined the expression of the two DAF genes in tissues of the wild-type and a strain of knockout mouse whose GPI-DAF gene has been inactivated. By fluorescence-activated cell sorting (FACS) analysis, we found that DAF protein is present on the wild-type mouse erythrocytes and lymphocytes but no signal was detectable on the same cells of GPI-DAF gene knockout mice. Both T and B lymphocytes and splenic macrophages express the GPI-DAF gene but the expression level is higher on B lymphocytes than on T lymphocytes. Within the T cell population, both CD4+ and CD8+ T cells are positive. DAF protein was detected by immunohistochemistry at high levels on wild-type mouse spermatids and mature sperm. In contrast, only mature sperm stained positive in the GPI-DAF gene knockout mouse testis, suggesting that GPI-DAF but not the TM-DAF gene is expressed on spermatids. Examination of the fetoplacental unit at the day 7.5 stage revealed that GPI-DAF but not the TM-DAF gene is expressed in the maternal decidua cells surrounding the trophoectoderm of the embryo. No DAF expression was detected on trophoblast or the embryo proper. These findings suggest that although the TM-DAF gene is irrelevant on mouse blood cells, the two DAF genes may have different roles in germ cell development and/or mature sperm function. Because complement receptor 1-related gene/protein y (Crry) has been shown to be expressed on early mouse embryos, the complete lack of GPI-DAF and TM-DAF gene expression in early mouse development may explain the observed sensitivity of Crry-deficient embryos to maternal complement attack.

Animals↗
PubMed2001

Tissue distribution of products of the mouse decay-accelerating factor (DAF) genes. Exploitation of a Daf1 knock-out mouse and site-specific monoclonal antibodies.

Decay-accelerating factor (DAF) is a membrane regulator of C3 activation that protects self cells from autologous complement attack. In humans, DAF is uniformly expressed as a glycosylphosphatidylinositol (GPI)-anchored molecule. In mice, both GPI-anchored and transmembrane-anchored DAF proteins are produced, each of which can be derived from two different genes (Daf1 and Daf2). In this report, we describe a Daf1 gene knock-out mouse arising as the first product of a strategy for targeting one or both Daf genes. As part of the work, we characterize recently described monoclonal antibodies against murine DAF protein using deletion mutants synthesized in yeast, and then employ the monoclonal antibodies in conjunction with wild-type and the Daf1 knock-out mice to determine the tissue distribution of the mouse Daf1 and Daf2 gene products. To enhance the immunohistochemical detection of murine DAF protein, we utilized the sensitive tyramide fluorescence method. In wild-type mice, we found strong DAF labelling of glomeruli, airway and gut epithelium, the spleen, vascular endothelium throughout all tissues, and seminiferous tubules of the testis. In Daf1 knock-out mice, DAF labelling was ablated in most tissues, but strong labelling of the testis and splenic dendritic cells remained. In both sites, reverse transcription-polymerase chain reaction analyses identified both GPI and transmembrane forms of Daf2 gene-derived protein. The results have relevance for studies of in vivo murine DAF function and of murine DAF structure.

Animals↗
PubMed2001

The lipopolysaccharide co-receptor CD14 is present and functional in seminal plasma and expressed on spermatozoa.

CD14 is a 54 000-molecular weight (MW) glycolipid-anchored membrane glycoprotein, expressed on myeloid cells, which functions as a member of the lipopolysaccharide (LPS) receptor complex. Soluble forms of CD14 have been reported in plasma, cerebrospinal fluid, amniotic fluid and breast milk. In plasma and breast milk, soluble CD14 has been implicated as a regulator of T- and B-cell activation and function. Expression of CD14 in the male reproductive system has not previously been investigated. We here show that soluble CD14 is present in seminal plasma at levels comparable to those in serum. Spermatozoa expressed CD14 on their membranes, as demonstrated by fluorescence microscopy and flow cytometry. Post-vasectomy, the levels of seminal plasma CD14 (spCD14) were much reduced, implying an origin distal to the point of transection of the vas deferens. Ultracentrifugation analyses demonstrated that spCD14 was not associated with lipid complexes, indicating that it lacks the glycolipid anchor. Purified spCD14 mediated activation by LPS of CD14-negative cells. These findings suggest that CD14 may play a hitherto unexplored role in immune defence and cell activation in the male reproductive tract.

Blotting, Western↗
PubMed2001

Agreement between general practice prescription data and self-reported use of hormone replacement therapy and treatment for various illnesses.

BACKGROUND: Epidemiological studies of the effects of hormone replacement therapy (HRT) often rely on exposure data and information on past health from self-administered questionnaires. The accuracy with which women report current use of HRT and the specific preparation in use is not known. This study aims to compare aspects of self-reported use of HRT and treatment for various conditions with data from general practice prescription records. METHODS: Reported questionnaire data on use of HRT were compared with those on the general practice prescription record for 570 women participating in the Million Women Study from two general practices in the UK. RESULTS: There was excellent agreement between data from the self-administered questionnaire and the prescription record: 96% agreement (kappa = 0.91) for current use of HRT, 95% agreement (kappa = 0.90) for any use of HRT during the period covered by the prescription record, and 97% agreement (kappa = 0.95) among current users for whether the HRT preparation contained oestrogen alone, combined oestrogen/progestogen, or some other constituents. Among former HRT users who provided questionnaire information on the preparation they used most recently, there was 69% agreement on the proprietary preparation used and 97% agreement (kappa = 0.93) on the hormonal constituents used. Agreement between reported treatment for various conditions and the presence of a prescription appropriate for that condition ranged from 89-99% (kappa 0.53-0.92), and was highest for thyroid disease and asthma. CONCLUSION: Important aspects of use of HRT, such as type of preparation currently being used, are reported very reliably by women completing a self-administered questionnaire.

Drug Prescriptions↗
PubMed2001

Obsessive-compulsive disorder and immunocompetence.

OBJECTIVE: A postinfectious, autoimmune response may be associated with the development of pediatric obsessive-compulsive disorder (OCD). According to this model, antistreptococcal antibodies cross-react with basal ganglia neurons following streptococcus infection. This autoimmune reaction disrupts a basal ganglia-thalamocortical circuit and generates obsessive-compulsive symptoms. One implication of this model is that prolonged immunologic stress may be a risk factor for OCD. That is, immunologic stress may compromise the blood-brain barrier and permit the influx of antistriatal antibodies into the central nervous system. This article explores one part of this putative relationship by investigating whether adult OCD patients, compared to members of other psychiatric groups, demonstrate a higher incidence of recurrent infections and other conditions suggestive of compromised immune function. METHOD: To test this hypothesis, we conducted a medical records review of 100 consecutive patients evaluated at a private psychiatric clinic specializing in the treatment of anxiety disorders. Sixty-five patients met diagnostic criteria for an Axis-I syndrome. Primary diagnoses included OCD, posttraumatic stress disorder, social anxiety disorder, generalized anxiety disorder, panic disorder with agoraphobia, and dysthymic disorder. Each medical record was reviewed for the presence of target syndromes or presenting symptoms suggestive of compromised immune function. RESULTS: Chart review revealed an increased rate of immune-related symptoms and syndromes among OCD patients in comparison to other anxiety and mood disorder groups. Groups did not differ significantly in the incidence of non-immune symptoms and syndromes. CONCLUSION: Adult OCD patients appear to have an increased rate of immune-related diseases above and beyond that seen in other psychiatric disorders.

Adult↗
PubMed2001

Illusory words created by repetition blindness: a technique for probing sublexical representations.

When two orthographically similar words are displayed using rapid serial visual presentation (RSVP), the repeated letters in the second critical word (W2) are not detected, leading to a deficit in reporting this word, a phenomenon known as repetition blindness (RB). The unrepeated letters in W2 do appear to be detected and available to feed activation to words compatible with them (Morris & Harris, 1999). When a fragment was strategically placed in the RSVP stream, as in GROW throw ank, observers reported seeing thank more often than in the control condition BEAT throw ank. Illusory words were facilitated by repetition blindness only when the recombining letters maintained their position in the words. Illusory word report was insensitive to the phonological similarity of the recombining letters; equal quantities of illusory words were created by sequences like china CHEAT THR (-->threat) and swung SWEAT THR (-->threat). In addition to being an interesting phenomenon in its own right, the illusory words paradigm may have considerable use as a tool for probing the perceptual units underlying visual word recognition.

Adult↗
PubMed2001

Are individual or consecutive letters the unit affected by repetition blindness?

When 2 similar words (e.g., react reach) are briefly sequentially displayed, the 2nd word may be omitted from the report, a phenomenon known as repetition blindness (RB). Previous researchers have suggested that consecutive letters are the unit affected by RB. Six experiments provided new data on orthographic RB. Two letters at the beginning or end of words resulted in RB, as did alternating interior letters (tactile earthly) and 3 letters with different relative positions (arid bird). However, no RB was found with a single final letter (show view). Observed RB may reflect pattern completion because RB for pairs like throat theory was reduced when the nonrepeated letters (eory) were consistent with only a single word. The experiments point to a model of orthographic RB in which both individual letters and letter sequences of length 2 or more play a role.

Adult↗
PubMed2000

Neurocognitive function in antisocial personality disorder.

Recent neuroimaging studies and neuropsychological test findings support the contention that prefrontal dysfunction is associated with psychopathic personality traits and antisocial behavior. However, conflicting results have arisen regarding performance on measures of frontal executive function. We administered a neuropsychological test battery consisting of measures sensitive to frontal lobe dysfunction and a battery of personality questionnaires and clinical scales sensitive to antisocial personality disorder (APD) subjects presenting with prominent psychopathic personality features and matched control subjects. We also monitored the subjects' electrodermal activity during the presentation of emotionally charged stimuli. APD subjects showed greater neuropsychological deficits on measures sensitive to orbitofrontal dysfunction in comparison to control participants. Moreover, APD subjects were electrodermally hyporesponsive to aversive stimuli relative to control group members. APD subjects did not demonstrate performance deficits on classical tests of frontal executive function. Participants also underwent clinical assessment. As expected, APD subjects were less conscientious, self-reproaching, guilt-prone, and socially anxious than matched control subjects. Moreover, the scores indicated that APD subjects were more venturesome and uninhibited relative to control subjects. Contrary to expectations, APD subjects and community control subjects did not differ on a self-report measure of sensitivity to specific phobic situations.

Antisocial Personality Disorder↗
PubMed2000

Pigs express multiple forms of decay-accelerating factor (CD55), all of which contain only three short consensus repeats.

We report the cloning of cDNAs encoding multiple isoforms of the pig analogue of human decay-accelerating factor (DAF; CD55). Screening of a pig muscle cDNA library using a human DAF probe identified a single clone that encoded a DAF-like molecule comprising three short consensus repeats (SCR) homologous with the amino-terminal three SCR in human DAF, a serine/threonine-rich (ST) region, and sequence compatible with a transmembrane domain and cytoplasmic tail. Northern blot and RT-PCR analysis showed that pig DAF was expressed in a wide range of tissues. Additional isoforms of DAF were sought using RT-PCR and 3'-rapid amplification of cDNA ends followed by sequencing. Isoforms containing a GPI anchor and with differing lengths of ST region were identified; no isoform containing a fourth SCR was found. Cloning of the GPI-anchored isoform from granulocytes confirmed that it was identical with the original transmembrane isoform through the three SCR and first portion of ST and was derived from a frame shift caused by splicing out 176 bp of sequence. A panel of mAbs was generated and used to analyze the distribution and anchoring of pig DAF in circulating cells. Pig DAF was expressed on all circulating cells and was transmembrane anchored on erythrocytes, but completely or partially GPI anchored on granulocytes and mononuclear cells. The transmembrane isoform of pig DAF was expressed on Chinese hamster ovary cells and was shown to affect regulatory activity for the classical pathway of human complement, but was only marginally active against pig serum.

Amino Acid Sequence↗
PubMed2000

Human and rodent decay-accelerating factors (CD55) are not species restricted in their complement-inhibiting activities.

Homologous complement activation is restricted on cells by the complement regulators, decay-accelerating factor (DAF), membrane cofactor protein (MCP) and CD59. These proteins act in concert with other membrane structures to protect cells from homologous complement attack. In contrast, cells are usually sensitive to heterologous complement attack. It has been suggested that species-specific restriction of complement activation can be attributed to the inability of regulators to inhibit across species. We have investigated the capacities of human, rat and mouse analogues of DAF to regulate homologous and heterologous complement. Cells transfected with cDNA encoding these analogues were protected from heterologous complement attack. C3b-deposition experiments indicated that whilst cells were best protected by DAF from the same species, all three analogues inhibited human, rat and mouse complement. Comparable results were obtained in haemolysis assays using soluble, recombinant forms of the proteins. Inhibition of the classical pathway (CP) was best achieved with homologous DAF, although human DAF also inhibited rat complement, rat DAF also inhibited human complement and mouse DAF inhibited complement from all species. Human DAF was the best inhibitor of alternative pathway (AP)-mediated attack, inhibiting complement from all species. Mouse DAF inhibited mouse and rat AP, whilst rat DAF inhibited only rat AP. These data indicate that human and rodent analogues of DAF are not species restricted and highlights interesting differences in the capacity to regulate AP and CP. This has implications in broader fields of research, such as xenotransplantation, where cross-species regulation of complement is of paramount importance.

Animals↗
PubMed2000

Effect of subarachnoid morphine administration on extubation time after coronary artery bypass graft surgery.

OBJECTIVE: To determine the effects of 2 low doses of intrathecal morphine on extubation time and on postoperative analgesic requirements after coronary artery bypass graft (CABG) surgery. DESIGN: A prospective, randomized, double-blind, placebo-controlled study. SETTING: Tertiary-care university hospital. PARTICIPANTS: Fifty adult patients scheduled for elective primary CABG surgery. INTERVENTIONS: Patients were randomized to receive placebo, 250 microg, or 500 microg intrathecal morphine, preoperatively. Intraoperative fentanyl and midazolam were limited to 15 microg/kg and 20 microg/kg intravenously. Patients were extubated in the intensive care unit by a blinded observer using predefined extubation criteria. MEASUREMENTS AND MAIN RESULTS: Time to extubation and postoperative requirements for morphine, midazolam, nitroglycerin, and sodium nitroprusside were recorded by a blinded observer. Extubation times were 441 +/- 207 minutes versus 325 +/- 188 minutes versus 409 +/- 245 minutes for the placebo, 250-microg, and 500-microg groups (p = 0.27). Postoperative morphine requirements in the 250-microg and 500-microg groups were 13.6 +/- 7.8 mg and 11.7 +/- 7.4 mg, compared with 21.3 +/- 6.2 mg in the placebo group (p = 0.001). There were no differences among the study groups with regard to postoperative midazolam, nitroglycerin, and sodium nitroprusside requirements. CONCLUSIONS: Despite decreased postoperative morphine requirements, intrathecal morphine administration did not have a clinically relevant effect on extubation time after CABG surgery. This study suggests that 250 microg is the optimal dose of intrathecal morphine to provide significant postoperative analgesia without delaying tracheal extubation.

Adolescent↗
PubMed2000

Orthographic repetition blindness.

Repetition blindness (RB) is the failure to report the second occurrence of a repeated word, when words are sequentially and briefly displayed (Kanwisher, 1987). RB is also observed for non-identical words, such as home, dome. Explanations for non-identity RB assume that similarity at the level of the whole word causes the second word to be suppressed ("similarity inhibition"). Three experiments demonstrate that RB is robust for diverse types of orthographic relatedness, including critical words that share only their first initial letter, their last two letters, first three letters, middle three letters, beginning and final letters, three alternating letters, and three non-aligned letters (as in chance hand). The theoretical construct of similarity inhibition may be able to account for these data, although one mechanism previously proposed in the literature, neighbourhood inhibition, is probably not a useful way to explain the data on RB for words sharing only one or two letters. We introduce an alternative explanation for orthographic RB: Only the repeated letters are suppressed, and amount of RB depends on how easily the perceiver can reconstruct the target word from the non-suppressed letters.

Adult↗