Biomedical subjects

A McClelland

Publications and source records attributed to A McClelland.

At least 37 records · Page 2Linked to original sources

PubMed1997

Prevention of rhinovirus infection in chimpanzees by soluble intercellular adhesion molecule-1.

Intercellular adhesion molecule-1 (ICAM-1) is the cell surface receptor for the major class of human rhinoviruses, and tICAM453, a truncated, soluble form of ICAM-1, has been shown previously to be a potent in vitro inhibitor of rhinovirus. In this report, we have investigated the in vivo efficacy of tICAM453 for the prophylaxis of rhinovirus serotype 16 infection in the chimpanzee. Because chimpanzees do not show clinical symptoms of infection after rhinovirus challenge, infection was followed by measuring antirhinovirus serum antibody responses and detection of virus shedding. By both of these measures, intranasal application of tICAM453 was efficacious in preventing rhinovirus infection in chimpanzees subsequently challenged with infectious doses of virus. These results suggest that the use of soluble rhinovirus receptor to inhibit virus binding to host cells should be feasible in humans.

Administration, Intranasal↗

PubMed1996

Complete short-term correction of canine hemophilia A by in vivo gene therapy.

Hemophilia A is a severe bleeding disorder caused by a deficiency in clotting factor VIII (FVIII). A canine model that closely mimics the human disease was used to determine if an adenoviral vector expressing a human FVIII cDNA could be used to correct the hemophilia A phenotype. Within 48 hours after peripheral vein administration of the vector to FVIII-deficient dogs, the hemophilic phenotype was corrected, based on determination of the activated clotting time, the activated partial thromboplastin time, and the cuticle bleeding time. Direct measurement of human FVIII in the dog plasma showed FVIII expression at amounts well above the human therapeutic level. FVIII expression in treated dogs was short-term, lasting 1 to 2 weeks, due to the development of a human FVIII-specific inhibitor antibody response. These data provide the first demonstration of in vivo gene therapy of hemophilia A.

Adenoviridae↗

PubMed1996

Sustained expression of therapeutic levels of human factor VIII in mice.

Deficiency of coagulation factor VIII (FVIII) results in hemophilia A, a common hereditary bleeding disorder. Using a human FVIII-encoding adenoviral vector, Av1ALAPH81, we have demonstrated expression of therapeutic levels of human FVIII in mice sustained for more than 5 months after vector administration. Administration of a high dose (4 x 10(9) plaque-forming units [pfu]) of Av1ALAPH81 to mice resulted in a peak expression of 2,063 ng/mL of human FVIII in the mouse plasma, with levels decreasing to background by weeks 15 to 17. Normal FVIII levels in humans range from 100 to 200 ng/mL and therapeutic levels are as low as 10 ng/mL. Alternatively, administration of 8- to 80-fold lower vector doses (5 x 10(8) pfu to 5 x 10(7) pfu) to normal adult mice resulted in expression of FVIII at therapeutic levels sustained for at least 22 weeks. Detailed analysis of vector toxicity indicated that the high vector dose caused a dramatic elevation of liver-specific enzyme levels, whereas an eight-fold lower vector dose was significantly less hepatotoxic. The data presented here demonstrate that administration of lower, less toxic vector doses allow long-term persistence of FVIII expression.

Adenoviruses, Human↗

PubMed1996

High-level tissue-specific expression of functional human factor VIII in mice.

Hemophilia A results from subnormal levels of blood coagulation factor VIII (FVIII) and is an attractive target for gene therapy. However, progress has been impeded by features of FVIII biology such as low mRNA accumulation and the instability of the protein. We have shown previously that a FVIII adenoviral vector, Av1ALH81, allowed high-level expression of human FVIII in mice sustained for several weeks. Here, we have generated a second FVIII adenoviral vector, Av1ALAPH81, in which an intron was introduced into the FVIII expression cassette. Administration of Av1ALAPH81 to mice resulted in significantly increased FVIII plasma levels, 1,046 +/- 163 ng/ml compared to 307 +/- 93 ng/ml of FVIII detected in mice that received Av1ALH81. Normal FVIII levels in humans are 100-200 ng/ml and therapeutic levels are as low as 10 ng/ml. Therapeutic levels are defined as the amount of FVIII necessary to convert severe hemophilia to a moderate or mild hemophiliac condition. The increased potency of the second FVIII adenoviral vector allowed the administration of significantly lower, less toxic vector doses, while retaining the potential for high FVIII expression. Furthermore, we demonstrate that adenoviral-mediated expression of human FVIII can be limited to the liver by inclusion of a liver-specific promoter, thereby achieving the first step in regulated expression of human FVIII in vivo.

Adenoviruses, Human↗

PubMed1996

Transient immunosuppression permits successful repetitive intravenous administration of an adenovirus vector.

The in vivo administration of adenovirus vectors frequently elicits a neutralizing antibody response which eliminates or substantially reduces the efficacy of subsequent treatments. Methods to overcome this significant barrier to repeat delivery will be required for the application of adenovirus-based gene therapy in the treatment of chronic disease. We have evaluated the relationship between the initial vector dose and the effectiveness of a second vector administration. C57BL/6 mice injected intravenously with up to 10(7) p.f.u. of a lacZ adenovirus vector, Av1lacZ4, expressed significant levels of human factor IX when injected with 2 x 10(8) p.f.u. of the factor IX vector, Av1H9F, 5 weeks later. An initial dose of 10(8) p.f.u. of Av1lacZ4 completely prevented expression of factor IX following the second administration due to the generation of neutralizing antibody. However, transient immunosuppression with deoxyspergualin (DSG) or cyclophosphamide at the time of initial exposure to 10(8) p.f.u. of Av1lacZ4 prevented the formation of anti-adenovirus neutralizing antibody and permitted an effective second administration of a factor IX vector. Furthermore, transient immunosuppression with cyclophosphamide concomitant with delivery of the factor IX vector enabled an effective administration of a third vector encoding human factor VIII. This approach, together with strategies to prolong the persistence of adenoviral vector expression, should permit long-term therapy with adenovirus-based vectors.

Adenoviruses, Human↗

PubMed1995

In vivo gene delivery and expression of physiological levels of functional human factor VIII in mice.

Hemophilia A is caused by blood coagulation factor VIII (FVIII) deficiency and is an attractive target for gene therapy. However, features of FVIII physiology, such as the instability of the mRNA and protein, have provided obstacles to the design of a feasible strategy for the transfer and expression of the human FVIII gene in vivo. We have constructed a recombinant adenoviral vector, Av1ALH81, that contains the human FVIII cDNA from which the B-domain has been deleted (BDD FVIII) and extensively characterized this vector in vitro and in vivo. In vitro, HepG2, human hepatoma cells, transduced with Av1ALH81 secreted high levels of biologically active human BDD FVIII measured by the Coatest bioassay (> 2,400 mU per 10(6) cells per 24 hr). Administration of Av1ALH81 to mice, via tail vein, resulted in expression of human BDD FVIII in the mouse plasma at levels averaging 307 +/- 93 ng/ml 1 week post-injection, measured by a sensitive human FVIII-specific ELISA. Normal FVIII levels in humans are 100-200 ng/ml, and therapeutic levels are as low as 10 ng/ml. Purification of the human FVIII from the mouse plasma, and subsequent Coatest analysis, revealed that the human FVIII produced in the mice was biologically active. In addition, the duration of FVIII expression in vivo was followed, and high-level FVIII expression was sustained over a period of several weeks. The finding that an adenoviral vector can mediate high-level expression of human FVIII in an animal model provides the basis for the development of gene therapy for hemophilia A.

Adenoviridae↗

PubMed1995

Endorsement and memory bias of self-referential pain stimuli in depressed pain patients.

This study investigates information processing in chronic pain patients by comparing the responses of depressed pain patients, non-depressed pain patients and non-pain control subjects. Each subject contributed two scores: endorsement of adjectives as descriptors of themselves and their best-friends; and free recall of the presented words. The stimuli consisted of depression-related, pain-related and neutral control adjectives, and each content category was split into negative and positive valence. The four-way interaction between group, reference, content and valence was significant both in the recall data and the endorsement data. Further analysis revealed that depressed pain patients exhibited a bias towards self-referential negative pain words, but not towards self-referential negative depression information. These results are interpreted in line with content specificity theory of information processing and have implications for targeting cognitive interventions with pain patients.

Adult↗

PubMed1995

Human adenovirus serotypes 3 and 5 bind to two different cellular receptors via the fiber head domain.

The adenovirus fiber protein is responsible for attachment of the virion to cell surface receptors. The identity of the cellular receptor which mediates binding is unknown, although there is evidence suggesting that two distinct adenovirus receptors interact with the group C (adenovirus type 5 [Ad5]) and the group B (Ad3) adenoviruses. In order to define the determinants of adenovirus receptor specificity, we have carried out a series of competition binding experiments using recombinant native fiber polypeptides from Ad5 and Ad3 and chimeric fiber proteins in which the head domains of Ad5 and Ad3 were exchanged. Specific binding of fiber to HeLa cell receptors was assessed with radiolabeled protein synthesized in vitro, and by competition analysis with baculovirus-expressed fiber protein. Fiber produced in vitro was found as both monomer and trimer, but only the assembled trimers had receptor binding activity. Competition data support the conclusion that Ad5 and Ad3 interact with different cellular receptors. The Ad5 receptor distribution on several cell lines was assessed with a fiber binding flow cytometric assay. HeLa cells were found to express high levels of receptor, while CHO and human diploid fibroblasts did not. A chimeric fiber containing the Ad5 fiber head domain blocked the binding of Ad5 fiber but not Ad3 fiber. Similarly, a chimeric fiber containing the Ad3 fiber head blocked the binding of labeled Ad3 fiber but not Ad5 fiber. In addition, the isolated Ad3 fiber head domain competed effectively with labeled Ad3 fiber for binding to HeLa cell receptors. These results demonstrate that the determinants of receptor binding are located in the head domain of the fiber and that the isolated head domain is capable of trimerization and binding to cellular receptors. Our results also show that it is possible to change the receptor specificity of the fiber protein by manipulation of sequences contained in the head domain. Modification or replacement of the fiber head domain with novel ligands may permit adenovirus vectors with new receptor specificities which could be useful for targeted gene delivery in vivo to be engineered.

Adenoviruses, Human↗

PubMed1995

Phenotypic correction of hypercholesterolemia in apoE-deficient mice by adenovirus-mediated in vivo gene transfer.

To investigate the potential use of apoE in gene therapy of hyperlipidemias, an adenoviral vector was constructed that contained the human apoE3 cDNA under the control of the RSV promoter (Av1RE). Transduction of HepG2 cells resulted in the overexpression of human apoE secreted into the culture medium. Intravenous injection of 5 x 10(11) Av1RE vector particles into apoE-deficient mice resulted in expression of human apoE3 in mouse plasma at levels of 1.2 +/- 0.4 micrograms/L (mean +/- SEM, n = 5) 7 days after injection. Mice injected with the control vector Av1Lacz4 did not express detectable levels of human apoE. Average plasma cholesterol concentrations were reduced approximately eightfold from 737.5 +/- 118 mg/dL (mean +/- SEM, n = 6) to 98.2 +/- 4.4 mg/dL (mean +/- SEM, n = 5) and were unaffected in the control vector group. Expression of human apoE resulted in a shift in the plasma lipoprotein distribution from primarily VLDL and LDL in the control mice to predominantly HDL in the Av1RE-treated group. Western blot analysis of fast protein liquid chromatography-fractionated mouse plasma showed that the human apoE protein was associated with VLDL, LDL, and HDL. Correction of the hyperlipidemic condition found in the apoE-knockout mouse strain by direct in vivo gene transfer establishes the potential of this approach for treatment of hyperlipidemia caused by apoE deficiency or malfunction in human disease.

Adenoviridae↗

PubMed1994

Crystallographic and cryo EM analysis of virion-receptor interactions.

Cryoelectron microscopy has been used to determine the first structure of a virus when complexed with its glycoprotein cellular receptor. Human rhinovirus 16 (HRV16) complexed with the two amino-terminal, immunoglobulin-like domains of the intercellular adhesion molecule-1 (ICAM-1) shows that ICAM-1 binds into the 12 A deep "canyon" on the surface of the virus. This is consistent with the prediction that the viral receptor attachment site lies in a cavity inaccessible to the host's antibodies. The atomic structures of HRV14 and CD4, homologous to HRV16 and ICAM-1, showed excellent correspondence with observed density, thus establishing the virus-receptor interactions.

Cell Adhesion Molecules↗

PubMed1994

Interpretation bias in responses to ambiguous cues in pain patients.

Pain patients and control subjects responses to ambiguous cues were compared in two separate investigations. In the first, pain patients, control subjects and physiotherapists were asked to produce a list of spontaneous associations to ambiguous cues (such as terminal and growth). To control for mood effects the experiment was repeated with three more groups: Pain patients, osteopaths and a control group. Measures of anxiety and depression were incorporated in the analysis. Results indicate that pain patients systematically produce more pain related associations than the other groups, and that this effect is independent of anxiety and depression levels. The discussion concentrates on the implications of these findings both for the theory of pain processing and for clinical interventions.

Adult↗

PubMed1993

Structure of a human rhinovirus complexed with its receptor molecule.

Cryoelectron microscopy has been used to determine the structure of a virus when complexed with its glycoprotein cellular receptor. Human rhinovirus 16 complexed with the two amino-terminal, immunoglobulin-like domains of the intercellular adhesion molecule 1 shows that the intercellular adhesion molecule 1 binds into the 12-A deep "canyon" on the viral surface. This result confirms the prediction that the viral-receptor attachment site lies in a cavity inaccessible to the host's antibodies. The atomic structures of human rhinovirus 14 and CD4, homologous to human rhinovirus 16 and intercellular adhesion molecule 1, showed excellent correspondence with observed density, thus establishing the virus-receptor interactions.

Antigens, CD↗

PubMed1993

Adenovirus mediated expression of therapeutic plasma levels of human factor IX in mice.

Gene therapy strategies designed to combat haemophilia B, caused by defects in clotting factor IX, have so far concentrated on ex vivo approaches. We have now evaluated adenoviral vector-mediated expression of human factor IX in vivo. Injection of the vector Av1H9B, which encodes human factor IX cDNA, into the tail veins of mice resulted in efficient liver transduction and plasma levels of human factor IX that would be therapeutic for haemophilia B patients. However, levels slowly declined to baseline by nine weeks and were not re-established by a second vector injection. These results address both the advantages and obstacles to the use of adenoviral vectors for treatment of haemophilia B.

Adenoviruses, Human↗

PubMed1993

Self-referential selective memory in pain patients.

The effect of self-reference on recall bias for pain stimuli was compared in chronic pain patients and controls. It was hypothesized that self-referential encoding would result in better recall of pain stimuli in chronic pain patients. In contrast, it was predicted that a non-pain control group would display no recall bias for pain-associated stimuli, regardless of the encoding reference. Subjects were tested in two conditions. The first condition (self-referential) involved encoding a list of words constructed from sensory pain, affective and neutral words. Elaboration at the encoding stage was achieved by asking subjects to imagine themselves in situations involving these words. Subjects were also asked to rate the likelihood of these situations occurring on a scale of 1 to 5 (from 1 = 'will not happen' to 5 = 'certain to happen'). The second condition (other-person reference) repeated this task in reference to another person with a matched list of words. A 2 x 2 x 3 factorial analysis of variance based on group x reference (self and other) x word type (sensory, affective and neutral) was carried out on recall scores, with the likelihood ratings as a covariate. Results reveal a significant three-way interaction. The analysis indicated that, while pain patients show an increase in recall of sensory words and a decrease in recall of neutral words when these are encoded in reference to themselves, control subjects show no difference in recall of these word types regardless of the encoding condition. The results support the notion that pain patients selectively recall more pain-associated words in comparison with other word types. However, this effect is only true for stimuli encoded in reference to themselves. It is proposed that this processing bias may contribute to the maintenance of a sense of helplessness and exacerbate the emotional impact of the pain experience.

Adult↗

PubMed1992

Preliminary X-ray crystallographic analysis of intercellular adhesion molecule-1.

Crystals of the two amino-terminal domains of intercellular adhesion molecule-1, the receptor for the major group of human rhinovirus serotypes, diffract to 3.0 A resolution. The crystals are trigonal in space group P3(1)21 or P3(2)21 with cell dimensions of a = b = 55.7 A, c = 166.3 A, with probably six molecules per unit cell.

Antigens, CD↗

PubMed1991

Identification of monoclonal antibody epitopes and critical residues for rhinovirus binding in domain 1 of intercellular adhesion molecule 1.

Intercellular adhesion molecule 1 (ICAM-1) is the cellular receptor for the major group of human rhinoviruses (HRVs) and the adhesion ligand of lymphocyte function-associated antigen 1. Analysis of a series of chimeric exchanges between human and murine ICAM-1 shows that two distinct epitopes recognized by monoclonal antibodies that block rhinovirus attachment and cell adhesion map to the N-terminal first domain of ICAM-1. Furthermore the specificity for HRV binding is entirely contained within the first 88 amino acids. Mutagenesis of the four sites of N-linked glycosylation within the second domain shows that carbohydrate is not involved in virus recognition. Homologue replacement mutagenesis localizes the epitopes for virus-blocking antibodies to two regions of domain 1 predicted to form beta strand D and the loop between the F and G strands of an immunoglobulin-fold structure. Analysis of virus binding to the mutants predicts a large surface of contact between HRV and ICAM-1 domain 1 but shows that the regions most important for virus binding are coincident with the monoclonal antibody epitopes.

Amino Acid Sequence↗

PubMed1991

Mechanisms of receptor-mediated rhinovirus neutralization defined by two soluble forms of ICAM-1.

The majority of human rhinoviruses use intercellular adhesion molecule 1 (ICAM-1) as a cell surface receptor. Two soluble forms of ICAM-1, one corresponding to the entire extracellular portion [tICAM(453)] and one corresponding to the two N-terminal immunoglobulin-like domains [tICAM(185)], have been produced, and their effects on virus-receptor binding, virus infectivity, and virus integrity have been examined. Results from competitive binding experiments indicate that the virus binding site is largely contained within the two N-terminal domains of ICAM-1. Virus infectivity studies indicate that tICAM(185) prevents infection by direct competition for receptor binding sites on virus, while tICAM(453) prevents infection at concentrations 10-fold lower than that needed to inhibit binding and apparently acts at the entry or uncoating steps. Neutralization by both forms of soluble ICAM-1 requires continual presence of ICAM-1 during the infection and is largely reversible. Both forms of soluble ICAM-1 can alter rhinovirus to yield subviral noninfectious particles lacking the viral subunit VP4 and the RNA genome, thus mimicking virus uncoating in vivo, although this irreversible modification of rhinovirus is not the major mechanism of virus neutralization.

Animals↗

PubMed1991

The facts behind the figures: a reply to Enderby and Davies (1989).

In 1989, Enderby and Davies discussed the type and pattern of speech and language therapy provision which would be required to service the needs of the speech- and language-impaired population of the UK, on the basis of statistical information drawn from a wide range of sources. In this paper, some methodological issues arising from their study are addressed and an argument made that alternative models of service provision should be considered when planning for future needs.

Cerebrovascular Disorders↗