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S J Russell

Publications and source records attributed to S J Russell.

At least 91 records · Page 5Linked to original sources
PubMed1995

Retroviral retargeting by envelopes expressing an N-terminal binding domain.

We have engineered ecotropic Moloney murine leukemia virus-derived envelopes targeted to cell surface molecules expressed on human cells by the N-terminal insertion of polypeptides able to bind either Ram-1 phosphate transporter (the first 208 amino acids of amphotropic murine leukemia virus surface protein) or epidermal growth factor receptor (EGFR) (the 53 amino acids of EGF). Both envelopes were correctly processed and incorporated into viral particles. Virions carrying these envelopes could specifically bind the new cell surface receptors. Virions targeted to Ram-1 could infect human cells, although the efficiency was reduced compared with that of virions carrying wild-type amphotropic murine leukemia virus envelopes. The infectivity of virions targeted to EGFR was blocked at a postbinding step, and our results suggest that EGFR-bound virions were rapidly trafficked to lysosomes. These data suggest that retroviruses require specific properties of cell surface molecules to allow the release of viral cores into the correct cell compartment.

Base Sequence↗
PubMed1995

Enhanced transduction efficiency of retroviral vectors coprecipitated with calcium phosphate.

Retroviral vectors are being used increasingly in clinical gene therapy protocols but low transduction frequencies are presenting a significant obstacle to progress. In this paper we report a simple method to enhance the efficiency of ex vivo retroviral gene transfer. Calcium chloride is added to the vector stock and calcium phosphate precipitates out of solution in complex with the retroviral vectors. When such coprecipitated vectors were used for gene transfer, the vector titres were increased at least five-fold and as much as 50-fold compared with the titres obtained in standard polybrene-enhanced infection protocols. Titre enhancement was not dependent on the starting concentration of vector, was equally effective for ecotropic and amphotropic vectors on a variety of mouse and human cells, and was not associated with any alteration in vector host range properties. The method may be of value to concentrate retroviral vectors and to enhance the efficiency of gene transfer in selected human gene therapy protocols.

Animals↗
PubMed1994

Replicating vectors for gene therapy of cancer: risks, limitations and prospects.

There are good theoretical arguments for exploring the use of replicating gene-transfer vectors for human cancer therapy. Such vectors should be derived from weakly pathogenic human viruses with initially broad tissue tropism. Coat protein engineering and promoter engineering might be used successfully to narrow the tropism of the vector, enhancing its ability to target tumour cells. Killing of uninfected 'bystander' tumour cells could be achieved through prodrug activation by a vector-encoded enzyme. Rapid elimination of infused vector particles by circulating antiviral antibody would limit access to tumour deposits after repeated administration, but might be circumvented by the use of infectious nucleic acid which is poorly imunogenic [64]. This putative therapeutic strategy is illustrated in Figure 1.

Gene Transfer Techniques↗
PubMed1994

Apolipoprotein E associates with beta amyloid peptide of Alzheimer's disease to form novel monofibrils. Isoform apoE4 associates more efficiently than apoE3.

Late-onset and sporadic Alzheimer's disease are associated with the apolipoprotein E (apoE) type 4 allele expressing the protein isoform apoE4. Apolipoprotein E binds avidly to beta amyloid (A beta) peptide, a major component of senile plaque of Alzheimer's disease, in an isoform-specific manner. The apoE4 isoform binds to A beta peptide more rapidly than apoE3. We observed that soluble SDS-stable complexes of apoE3 or apoE4, formed by coincubation with A beta peptide, precipitated after several days of incubation at 37 degrees C with apoE4 complexes precipitating more rapidly than apoE3 complexes. A beta(1-28) and A beta(1-40) peptides were incubated in the presence or absence of apoE3, apoE4, or bovine serum albumin for 4 d at 37 degrees C (pH 7.3). Negative stain electron microscopy revealed that the A beta peptide alone self-assembled into twisted ribbons containing two or three strands but occasionally into multistranded sheets. The apoE/A beta coincubates yielded monofibrils 7 nm in diameter. ApoE4/A beta coincubates yielded a denser matrix of monofibrils than apoE3/A beta coincubates. Unlike purely monofibrillar apoE4/A beta coincubates, apoE3/A beta coincubates also contained double- and triple-stranded structures. Both apoE isoforms were shown by immunogold labeling to be uniformly distributed along the A beta peptide monofibrils. Monofibrils appeared earlier in apoE4/A beta than in apoE3/A beta in time-course experiments. Thus apoE3 and apoE4 each interact with beta amyloid peptide to form novel monofibrillar structures, apoE4 more avidly, a finding consistent with the biochemical and genetic association between apoE4 and Alzheimer's disease.

Alzheimer Disease↗
PubMed1994

Gene transfer technologies for the gene therapy of cancer.

Gene therapy for cancer relies upon the delivery of a therapeutic gene to a target cell population which may comprise either the tumour cells themselves or specific host effector cells with anti-tumour activity. In addition, gene delivery may be targeted directly to the tumour cells in vivo or towards cells explanted from the patient. The precise requirements of the delivery system depend upon the specific therapeutic strategy being used. In each case, however, delivery must be accurate, efficient and must result in correctly regulated expression of the gene in only the desired cell type. Equally important, the delivery system must be safe for both the patient and the community as a whole. Here, we summarize the types of gene therapy which have been proposed for the treatment of cancer and review how currently available delivery systems are suited to each of these individual strategies.

Adenoviridae↗
PubMed1994

Replicating vectors for cancer therapy: a question of strategy.

Direct gene transfer to tumor cells in vivo may have considerable therapeutic potential, provided that a high enough efficiency of gene delivery can be achieved. All other things being equal (e.g. dose, route of administration), a replicating vector should give a higher efficiency of gene transfer than a nonreplicating vector due to local spread from the initially transduced cells. Almost any virus could provide the basis for a replicating gene transfer vector but, for the treatment of human cancer, the choice is greatly constrained by issues of public safety and potential efficacy. Public safety considerations point to viruses of low pathogenicity which are already prevalent in the human population whilst efficacy considerations point to viruses which replicate efficiently in the tumor cells to be targeted. Additional factors influencing the suitability of individual viruses as a basis for replicating vectors include the availability of an infectious molecular clone, the capacity for foreign gene insertion, genomic stability, potential for targeting by coat protein engineering or promoter engineering, cell-cycle dependence and availability of an effective vaccine.

Gene Transfer Techniques↗
PubMed1994

Haemorrhagic cystitis in paediatric bone marrow transplant patients: an association with infective agents, GVHD and prior cyclophosphamide.

The frequency of haemorrhagic cystitis (HC) is evaluated in a paediatric population undergoing bone marrow transplantation (BMT) and its relationship to therapy with cyclophosphamide (CY) prior to conditioning for BMT (prior CY), infectious agents and graft-versus-host disease (GVHD) assessed. HC was defined as macroscopic haematuria with early onset HC occurring within 2 days of and delayed onset beyond 2 days from CY infusion. Sixty-three children received a total of 65 BMTs between July 1988 and January 1991, with 60 children receiving CY and 3 l/m2/24 h of post-hydration fluid post-CY as part of their conditioning. There were no cases of early onset HC. Eleven (17%) children had a total of 19 episodes of delayed onset HC. Overall, an infective agent was identified in the urine at the time of 17 of 19 (89%) episodes of HC. While papovavirus was the most common organism (12 episodes), adenovirus (2), cytomegalovirus (1) and bacteria (3) were also identified. The frequency of HC in transplants complicated by acute GVHD grade II-IV was 40% (p = 0.016), in children who had received prior CY was 43% (p < 0.001) and in mismatched transplants was 32% (p = 0.06). Four children who developed GVHD had exacerbations of symptoms associated with the use of high-dose steroid therapy. Our results suggest that most cases of delayed onset HC are temporally associated with an infective organism, predominantly papovavirus, and identify GVHD and prior CY as risk factors. Increased symptomatology was associated with acute GVHD and its treatment and this may be explained by the added immune suppression, resulting in greater viral reactivation and further mucosal damage.

Adolescent↗
PubMed1993

The contribution of contact and non-contact residues of antibody in the affinity of binding to antigen. The interaction of mutant D1.3 antibodies with lysozyme.

We have analysed the contribution of residues of the D1.3 Fv fragment to binding of hen egg lysozyme. We altered residues at the contact interface by site-directed mutagenesis, and determined the affinity of the mutant Fv fragments for lysozyme by fluorescence quench titration. We found that a band of residues at the centre of the contact interface were much more important for binding affinity than those at the periphery. We also subjected the seFv fragment to random mutagenesis to simulate somatic mutation and affinity maturation. By display of the mutants on the surface of filamentous phages, and selection of the phages with biotinylated lysozyme, we were able to select mutants with modest improvements in binding affinity to lysozyme. By combining the mutations we obtained a scFv fragment with a fivefold improved affinity (Kd approximately 0.6 nM compared to wild-type Kd = 3.3 nM). However, none of the altered residues leading to improved affinity was located in the contact interface. This indicates that the interactions of a few residues at the centre of the contact interface are responsible for the binding affinity to antigen, but that these interactions can be modulated by alterations of residues outside the binding site. This may represent a typical mechanism for the affinity maturation of antibodies.

Animals↗
PubMed1993

Immunization with interleukin-2-secreting allogeneic mouse fibroblasts expressing melanoma-associated antigens prolongs the survival of mice with melanoma.

The survival of C57BL/6 mice (H-2b) bearing B16 melanoma (H-2b) was prolonged if the animals were treated solely by immunization with an interleukin-2 (IL-2)-secreting allogeneic cell construct that expressed melanoma-associated antigens (MAA) along with major histocompatibility complex (MHC) class-I determinants (H-2k; RLBA-IL-2 cells). This was the case if the mice were immunized simultaneously with, or 6 days following, the injection of viable B16 cells. Under similar conditions, the survival of tumor-bearing mice immunized with an allogeneic cell construct (H-2k) that expressed MAA but did not secrete IL-2 (RLBA-ZipNeo cells), or with an allogeneic construct (H-2k) that secreted IL-2 but did not form MAA (LM-IL-2 cells), was also prolonged. However, in these instances, the period of survival was significantly shorter than that of mice immunized with the cell construct that combined IL-2 secretion with the expression of MAA. Tumor-bearing mice immunized with non-transfected LM(TK-) cells (H-2k), or irradiated B16 cells (H-2b) failed to survive longer than untreated mice. Although the survival of the treated animals was prolonged, in most instances tumor growth recurred. The recurrent tumors in mice treated with the allogeneic cell constructs formed melanin and were histologically indistinguishable from tumors in untreated mice. Cells from the recurrent tumors were resistant to further immunotherapy and to cytotoxic effector cells obtained from the spleens of mice immunized with the same cellular immunogen used initially. The injection of IL-2-secreting syngeneic B16 cells into C57BL/6 mice invariably resulted in the appearance of non-IL-2-secreting melanomas. Under similar circumstances, tumors failed to develop in C57BL/6 mice injected with IL-2-secreting, or non-secreting, allogeneic cell constructs. Thus, the expression of allogeneic antigens protected the mice from growth of the cellular immunogens.

Animals↗
PubMed1993

Retroviral vectors displaying functional antibody fragments.

We have made retrovirus particles displaying a functional antibody fragment. We fused the gene encoding an antibody fragment directed against a hapten with that encoding the viral envelope protein (Pr80env) of the ecotropic Moloney murine leukemia virus. The fusion gene was co-expressed in ecotropic retroviral packaging cells with a retroviral plasmid carrying the neomycin phosphotransferase gene (neo), and retroviral particles with specific hapten binding activities were recovered. Furthermore the hapten-binding particles were able to transfer the neo gene and the antibody-envelope fusion gene to mouse fibroblasts. In principle, the display of antibody fragments on the surface of recombinant retroviral particles could be used to target virus to cells for gene delivery, or to retain the virus in target tissues.

3T3 Cells↗
PubMed1993

Mutation of Asp20 of human interleukin-2 reveals a dual role of the p55 alpha chain of the interleukin-2 receptor.

Mutation of Asp20 in human interleukin-2 (IL-2) to Lys is known to result in an IL-2 molecule with unchanged binding to the p55 subunit of the IL-2 receptor, but with greatly decreased affinity for the p75 subunit (Collins, L., Tsien, W.-H., Seals, C. et al. Proc. Natl. Acad. Sci USA 1988. 85: 7709). Here we demonstrate that Lys20 IL-2 competed with a reduced (10-fold) affinity for high-affinity IL-2 receptors on two murine cell lines HT2 and CTLL. In parallel with this difference in receptor interaction, Lys20 IL-2 stimulated half-maximal HT2 cell proliferation at a 10-fold higher concentration than wild-type IL-2. However, half-maximal stimulation of CTLL cells required a 100-fold higher concentration of Lys20 IL-2. A similar 100-fold reduction in bioactivity of Lys20 IL-2 was observed for primary, activated, human or murine lymphocytes. Anti-p55 antibodies increased the concentration of Lys20 IL-2 required to stimulate HT2 cells to that required for CTLL cells. These data suggest that CTLL cells, while able to bind Lys20 IL-2 with high affinity, are lacking a p55-dependent function necessary for optimal stimulation. Therefore, p55 has a dual role, being important both for high-affinity IL-2 binding and for optimal cell triggering.

Animals↗
PubMed1993

Hypolipidemic effects of nicotinic acid in patients with familial defective apolipoprotein B-100.

Familial defective apolipoprotein B-100 (FDB) is a dominantly inherited disorder associated with hypercholesterolemia, in which an amino acid substitution in apolipoprotein B-100 results in low-density lipoprotein (LDL) particles that bind poorly to the LDL receptor and accumulate in plasma. Patients with FDB described to date have been heterozygous for this disorder, and their plasma contains both normal and defective-binding LDL particles. We have evaluated the hypocholesterolemic effects of nicotinic acid (3 g/d) in four patients with FDB, and compared the response to that of nine patients with heterozygous familial hypercholesterolemia (FH). Concentrations of LDL decreased by 24% in patients with FDB and by 14% in patients with FH. These results support the view that drugs which reduce LDL synthesis may be particularly effective in the treatment of patients with FDB.

Adult↗
PubMed1993

Comparison of the potential therapeutic effects of interleukin 2 or interleukin 4 secretion by a single tumour.

Engineering of a variety of rodent tumour cells to secrete either interleukin 2 (IL-2), or interleukin 4 (IL-4), has been demonstrated to reduce their tumorigenicity. However the mechanisms of action of secreted IL-2 and IL-4 have not been compared in a single rodent tumour. Here we demonstrate that the weakly immunogenic murine fibrosarcoma FS29 had reduced growth rate and in some cases was rejected by syngeneic animals, when modified to secrete either IL-2 or IL-4, but not IL-5. Immunohistochemical analysis of tumour nodules undergoing regression showed stimulation of a largely lymphocytic infiltrate by IL-2 and a macrophage and granulocyte infiltrate, with a small number of lymphocytes by IL-4. Indeed, secretion of low levels of IL-2 and IL-4 in combination resulted in optimal rejection, suggesting that the two cytokines might mobilise different and complementary effector cell mechanisms. Both IL-2 and IL-4-secreting cells failed to induce the rejection of admixed, unmodified FS29 cells. The loss of cytokine secreting cells from such admixtures occurred more rapidly for IL-2-secreting cells. Injection of IL-4-secreting, but not IL-2-secreting FS29 cells could protect mice from a delayed challenge with unmodified FS29 cells. These data suggest that IL-4 secretion stimulates the better long-term host anti-tumour response.

Animals↗
PubMed1993

A genetic approach to idiotypic vaccination.

Treatment of cancer with vaccines is an attractive prospect, but few tumours express suitable target antigens. With B-cell lymphomas, the idiotypic immunoglobulin (Ig) of the malignant B-cell should provide a suitable target but this requires a vaccine to be created for each patient. We propose a strategy for making such vaccines: first to clone the V genes of the idiotypic Ig, and second to inject the patient with the cloned DNA (genetic immunisation) in order to elicit an immune response against the encoded Ig. We have previously shown that the V genes of the idiotypic Ig can be identified from human lymph node biopsies by polymerase chain reaction amplification, cloning, and sequencing. In this report, we show that anti-idiotypic antibodies can be elicited by direct injection of an expression vector that encodes the V genes of murine antibodies (the V genes of B1.8, a murine hybridoma or of BCL1, a murine lymphoma line). This finding suggests a simple approach to the preparation of idiotypic vaccines for patients with B-cell lymphoma, which also circumvents the need for adjuvants.

Animals↗
PubMed1993

Cytokine gene transfer as a therapeutic strategy.

Cytokine gene therapy for cancer could involve either the direct delivery of cytokine genes to established tumours to stimulate their rejection or the injection of cytokine-secreting tumour cells to stimulate an immune response that could reduce metastatic disease. To assess the feasibility of the first approach, we have compared the ability of different cytokine-secreting tumour cells to induce the rejection of admixed, unmodified cells. While interleukin (IL)-2- or interleukin-4-secreting tumour cells were ineffective, interferon-gamma (IFN-gamma)-secreting cells could induce rejection of 10% admixed, unmodified cells. Because direct gene delivery to tumours is unlikely to be 100% efficient, these data suggest that IFN-gamma may be the most suitable of these cytokines for this approach. However, we have demonstrated that injection of IL-2-secreting tumour cells, following primary tumour excision, can prevent the development of metastases and prolong survival of rats. This suggests that IL-2-secreting tumour cells can be effective in the treatment of metastatic disease.

Animals↗
PubMed1993

A unique haplotype of the apolipoprotein B-100 allele associated with familial defective apolipoprotein B-100 in a Chinese man discovered during a study of the prevalence of this disorder.

The prevalence of familial defective apolipoprotein (apo) B-100 (FDB) was determined by sampling 5,160 volunteer subjects from among 14,058 eligible employees of a bank in California. The sample was ethnically diverse (44.6% of the population was non-Caucasian). The prevalence of FDB in the study population was 0.08% with a 90% confidence interval of 0.01-0.14%. Four subjects were found to have the apoB 3500 codon mutation by mutagenic polymerase chain reaction, which creates an MspI site at the 3500 codon of normal alleles but not alleles coding for the Arg-->Gln mutation of FDB. Three of these were Caucasian and born in North America. The fourth was a native of China. Haplotype analysis of the affected allele of the Chinese subject using 10 markers described by Ludwig and McCarthy (1990. Am. J. Hum. Genet. 47: 712-720) revealed a unique haplotype that differed from the haplotype of all other subjects with FDB. This unique allele had 30 repeats of a 3' hypervariable element instead of 48 as was found in the allele associated with FDB in other subjects, and in the 3' region there was an EcoRI site that was also not present in the allele most commonly found in association with FDB. We conclude that the prevalence of FDB in our ethnically diverse population is lower than that reported in previous studies of predominantly Caucasian populations and that the Chinese subject represents either an independent mutation or possibly recombination at the 3' end of the apoB gene, an event not previously described.

Adult↗
PubMed1992

Principles of antibody therapy.

The success of monoclonal antibodies in clinical practice is dependent on good design. Finding a suitable target is the most important part as other properties of the antibody can be altered by genetic engineering. Antibodies that target lymphocyte antigens offer less toxic immunosuppressive treatment than currently available drugs and the first monoclonal antibody approved for human use is an immunosuppressive agent for treating rejection of renal transplants. Human trails of monoclonal antibodies to treat septic shock have been done and antibodies are also being developed to target common pathogens such as herpes simplex virus. Although monoclonal antibodies against cancer have been much heralded, their success has been limited by the poor access to the inside of tumours. Treatment of blood cancers has been more successful and a human antibody against B cell malignancies is being clinically tested. As knowledge about natural immune responses and antibody engineering increases many more monoclonals are likely to feature in clinical practice.

Antibodies, Monoclonal↗