126
|
Abstract
Epidemiology works in a public domain, gathering the results of surveys and trials into forms of knowledge which are made available to many stakeholders. Health policy makers, lawyers, the media, medical technology companies, and those who use and deliver health services all have legitimate interests in epidemiology. There is unfortunately no common language in which each of these stakeholders can express their interest in the outcomes of epidemiological studies. The largest and most important gap exists between those who use computational data and those who use cultural and linguistic models to generate their explanations. Methods have been described, however, which allow the identification of all legitimate stakeholders before epidemiological studies are undertaken. Identifying the stakeholders, however, will serve no purpose unless there is a prior commitment by epidemiologists to respect both reductionist and narrative accounts of truth.
Collapse
|
127
|
Little M. Resource constraints and moral pressures: can we still afford ourselves? THE AUSTRALIAN AND NEW ZEALAND JOURNAL OF SURGERY 1998; 68:757-9. [PMID: 9814735 DOI: 10.1111/j.1445-2197.1998.tb04670.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have reached a phase of diminishing returns in medicine. Increasing costs produce smaller and smaller incremental benefits in health status. Medical scientists continue to work within the ideology of the Enlightenment, whereby advances in knowledge will eventually lead to control of health and welfare. The enormous costs of this ideology have led to two new ideologies: those of economic rationalism and managerialism. At the public level, the Western liberal emphasis on the value of individual life is generally held to justify the amount of public money spent on health. Those who frame health policy are influenced to some extent by this ideal, but we cannot continue to develop costly interventions without constraint. To overcome this impasse, we might accept that economic rationalism provided a proper base for health care; or we might redefine disease so that more people were excluded from treatment programmes; or we might agree to limit medical research in costly areas; we might change our ethical thinking to emphasize classical utilitarianism; or we might undertake systematic studies of community values and opinions to find out what people really want from their health and welfare services. There are serious ethical problems with each of these solutions, except for the last: the idea of modifying services to take note of community values. Testing community values is difficult, but there are ways of doing it, and there have been some exercises in which the process has been undertaken with some success. The recent Constitutional convention suggests that it may even be possible in Australia.
Collapse
|
128
|
Little M, Jordens CF, Paul K, Montgomery K, Philipson B. Liminality: a major category of the experience of cancer illness. Soc Sci Med 1998; 47:1485-94. [PMID: 9823044 DOI: 10.1016/s0277-9536(98)00248-2] [Citation(s) in RCA: 179] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Narrative analysis is well established as a means of examining the subjective experience of those who suffer chronic illness and cancer. In a study of perceptions of the outcomes of treatment of cancer of the colon, we have been struck by the consistency with which patients record three particular observations of their subjective experience: (1) the immediate impact of the cancer diagnosis and a persisting identification as a cancer patient, regardless of the time since treatment and of the presence or absence of persistent or recurrent disease; (2) a state of variable alienation from social familiars, expressed as an inability to communicate the nature of the experience of the illness, its diagnosis and treatment; and (3) a persistent sense of boundedness, an awareness of limits to space, empowerment and available time. These subjectivities were experienced in varying degree by all patients in our study. Individual responses to these experiences were complex and variable. The experiences are best understood under the rubric of a category we call "liminality". We believe that all cancer patients enter and experience liminality as a process which begins with the first manifestations of their malignancy. An initial acute phase of liminality is marked by disorientation, a sense of loss and of loss of control, and a sense of uncertainty. An adaptive, enduring phase of suspended liminality supervenes, in which each patient constructs and reconstructs meaning for their experience by means of narrative. This phase persists, probably for the rest of the cancer patient's life. The experience of liminality is firmly grounded in the changing and experiencing body that houses both the disease and the self. Insights into the nature of the experience can be gained from the Existentialist philosophers and from the history of attitudes to death. Understanding liminality helps us to understand what it is that patients with cancer (and other serious illnesses) seek from the system to which they turn for help. Its explication should therefore be important for those who provide health care, those who educate health care workers and those concerned to study and use outcomes as administrative and policy making instruments.
Collapse
|
129
|
Abstract
For the treatment of minimal residual disease in patients with leukemias and malignant lymphomas, we constructed a heterodimeric diabody specific for human CD19 on B cells and CD3epsilon chain of the T cell receptor complex. The bispecific diabody was expressed in Escherichia coli using a vector containing a dicistronic operon for co-secretion of V(H)3-V(L)19 and V(H)19-V(L)3 single-chain Fv fragments (scFv). It was purified in one step by immobilized metal affinity chromatography (IMAC) from the periplasmic extract and culture medium. Flow cytometry experiments revealed specific interactions of the diabody with both CD3 and CD19 positive cells, to which it bound with affinities close to those of the parental scFvs. It was less stable than anti-CD3 scFv but more stable than anti-CD19 scFv when incubated in human serum at 37 degrees C. In cytotoxicity tests, the diabody proved to be a potent agent for retargeting peripheral blood lymphocytes to lyse tumor cells expressing the CD19 antigen. The efficiency of cell lysis compared favorably with that obtained with a bispecific antibody (BsAb) of the same dual specificity that was prepared by the quadroma technique.
Collapse
|
130
|
Little M, Hudson DW, Pereira PL. Antivenoms and helicopter rescue services. Med J Aust 1998; 169:229-30. [PMID: 9734588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
|
131
|
Rondot S, Anthony KG, Dübel S, Ida N, Wiemann S, Beyreuther K, Frost LS, Little M, Breitling F. Epitopes fused to F-pilin are incorporated into functional recombinant pili. J Mol Biol 1998; 279:589-603. [PMID: 9641980 DOI: 10.1006/jmbi.1998.1773] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In order to develop a system which allows infection by an epitope-specific phage-antibody via an F-pilus expressing that epitope, a study on the expression of foreign sequences on F-pilin was undertaken. Initially, a plasmid library was constructed with random sequences encoding one to five amino acid residues fused to the C terminus of F-pilin (traA) which was used to complement an F-plasmid with an amber mutation in traA. Functional F-pilin fusions were detected using the filamentous phage, fUSE2, which transduces tetracycline resistance, as well as immunoblots using a monoclonal antiserum specific for the acetylated N terminus of pilin. All the clones selected expressed the pilin-fusions and displayed full sensitivity towards fUSE2 infection, which was indistinguishable from the wild-type F-pilin. The sequences of fUSE2-sensitive clones when compared to randomly selected clones which were not fUSE2-sensitive, revealed no obvious pattern in the amino acid residues fused to the C terminus, except for a preference for a hydrophilic amino acid at position +1. Mutating the C-terminal Leu in wt (wild-type) pilin to Ser blocked pilus assembly and fUSE2 infection; the pilin was correctly processed but the level of acetylation at the N terminus appeared to decrease. Fusing a known epitope (myc) directly to the C terminus blocked processing of F-pilin leading to loss of F-pilus assembly and function. The introduction of random sequences between traA and this epitope yielded fully recombinant, functional F-pili but this appeared to be due to processing of the extension by an unidentified protease leading to loss of the epitope. Surface expression of another epitope (G2-10) was clearly demonstrated by immuno-electron microscopy of pili with a G2-10 monoclonal antibody. A different five amino acid residue spacer between the F-pilin C terminus and the G2-10 epitope produced a system that was transfer-proficient and fUSE2-sensitive, but the pili were barely detectable by immunoblots or by electron microscopy. While the underlying rules that govern successful epitope expression at the C terminus of F-pilin remain elusive, many types of foreign sequences can be displayed with varying degrees of success. Our results also suggest that pilin sequence determines a number of steps in the complex pathway for pilus assembly.
Collapse
|
132
|
Jellinek M, Little M. Supporting child psychiatric services using current managed care approaches: you can't get there from here. ARCHIVES OF PEDIATRICS & ADOLESCENT MEDICINE 1998; 152:321-6. [PMID: 9559705 DOI: 10.1001/archpedi.152.4.321] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
For-profit behavioral health care companies have transformed the way mental health services are provided for children. Using marketplace approaches, companies have "carved out" mental health services for many patients receiving care from pediatricians. This report details specific approaches used by these firms to maximize profits, minimize the role of child and adolescent psychiatrists, and limit clinical services. Understanding for-profit carveouts will help primary care pediatricians appreciate the likely consequences of such reimbursement incentives for the care of children and their families.
Collapse
|
133
|
Little M. Euthanasia--crossing the Rubicon or at the cross roads? AUSTRALIAN AND NEW ZEALAND JOURNAL OF MEDICINE 1998; 28:55-56. [PMID: 9544387 DOI: 10.1111/j.1445-5994.1998.tb04459.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
|
134
|
Murphy JM, Wehler CA, Pagano ME, Little M, Kleinman RE, Jellinek MS. Relationship between hunger and psychosocial functioning in low-income American children. J Am Acad Child Adolesc Psychiatry 1998; 37:163-70. [PMID: 9473912 DOI: 10.1097/00004583-199802000-00008] [Citation(s) in RCA: 177] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE Using large-scale surveys from nine states, the Community Childhood Hunger Identification Project (CCHIP) estimates that 8% of American children under the age of 12 years experience hunger each year. CCHIP operationalizes child hunger as multiple experiences of parent-reported food insufficiency due to constrained resources. The current study examined the relationship between food insufficiency and school-age, low-income children's psychosocial functioning. The study also assessed the interinformant (parent versus child) reliability and time-to-time reliability of the CCHIP measure. METHOD Two hundred four school-age children and their parents from four inner-city public schools were interviewed using parent, teacher, and clinician report measures of psychosocial functioning. Ninety-six children and their parents were reinterviewed 4 months later. RESULTS Hungry and at-risk for hunger children were twice as likely as not-hungry children to be classified as having impaired functioning by parent and child report. Teachers reported higher levels of hyperactivity, absenteeism, and tardiness among hungry/at-risk children than not-hungry children. Parent and child reports of hunger were significantly related to each other, and time-to-time reliability of the CCHIP measure was acceptable. CONCLUSIONS Results of this study suggest that intermittent experiences of food insufficiency and hunger as measured by CCHIP are associated with poor behavioral and academic functioning in low-income children. The current study also supports the validity and reliability of the CCHIP measure for assessing hunger in children.
Collapse
|
135
|
Welschof M, Little M, Dörsam H. Production of a Human Antibody Library in the Phage-Display Vector pSEX81. METHODS IN MOLECULAR MEDICINE 1998; 13:593-603. [PMID: 21390868 DOI: 10.1385/0-89603-485-2:593] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Human monoclonal antibodies (MAbs) are more suitable than MAbs of animal origin for clinical applications because of lower hypersensitivity reactions, less formation of circulating immune complexes and lower anti-immunoglobulin responses The classical production of human MAbs via the hybridoma technique or Epstein-Barr virus (EBV) transformation is limited by the instability of cell lines, low antibody production, and the problems of imununizing humans with certain antigens (1,2). A promising alternative 1s the production of human recombinant antibodies (3). Recombinant DNA technology has made it possible to clone human antibody genes in vectors and to generate antibody expression libraries (4-7). One approach has been to amplify and recombine the IgG repertoire of an "immunized" donor. This has been used to isolate several antibodies related to diseases (8,9). In order to obtain more universal antibody libraries the naive IgM repertoire of several "unimmunized" donors were pooled (10,12). The complexity of the combinatorial libraries has been further increased by creating the so-called "semisynthetic" antibody libraries (22-14).
Collapse
|
136
|
Kleinman RE, Murphy JM, Little M, Pagano M, Wehler CA, Regal K, Jellinek MS. Hunger in children in the United States: potential behavioral and emotional correlates. Pediatrics 1998; 101:E3. [PMID: 9417167 DOI: 10.1542/peds.101.1.e3] [Citation(s) in RCA: 199] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
OBJECTIVE Results from a recent series of surveys from 9 states and the District of Columbia by the Community Childhood Hunger Identification Project (CCHIP) provide an estimate that 4 million American children experience prolonged periodic food insufficiency and hunger each year, 8% of the children under the age of 12 in this country. The same studies show that an additional 10 million children are at risk for hunger. The current study examined the relationship between hunger as defined by the CCHIP measure (food insufficiency attributable to constrained resources) and variables reflecting the psychosocial functioning of low-income, school-aged children. METHODS The study group included 328 parents and children from a CCHIP study of families with at least 1 child under the age of 12 years living in the city of Pittsburgh and the surrounding Allegheny County. A two-stage area probability sampling design with standard cluster techniques was used. All parents whose child was between the ages of 6 and 12 years at the time of interview were asked to complete a Pediatric Symptom Checklist, a brief parent-report questionnaire that assesses children's emotional and behavioral symptoms. Hunger status was defined by parent responses to the standard 8 food-insufficiency questions from the CCHIP survey that are used to classify households and children as "hungry," "at-risk for hunger," or "not hungry." RESULTS In an area probability sample of low-income families, those defined as hungry on the CCHIP measure were significantly more likely to have clinical levels of psychosocial dysfunction on the Pediatric Symptom Checklist than children defined as at-risk for hunger or not hungry. Analysis of individual items and factor scores on the Pediatric Symptom Checklist showed that virtually all behavioral, emotional, and academic problems were more prevalent in hungry children, but that aggression and anxiety had the strongest degree of association with experiences of hunger. CONCLUSION Children from families that report multiple experiences of food insufficiency and hunger are more likely to show behavioral, emotional, and academic problems on a standardized measure of psychosocial dysfunction than children from the same low-income communities whose families do not report experiences of hunger. Although causality cannot be determined from a cross-sectional design, the strength of these findings suggests the importance of greater awareness on the part of health care providers and public health officials of the role of food insufficiency and hunger in the lives of poor children.
Collapse
|
137
|
Little M, Dübel S, Kipriyanov S, Breitling F. Recent developments in antibody engineering. METHODS IN MOLECULAR MEDICINE 1998; 13:555-580. [PMID: 21390866 DOI: 10.1385/0-89603-485-2:555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Rapid growth in the field of antibody engineering occurred after it was shown that functional antibody fragments could be secreted into the periplasmic space and even into the medium of Escherichia coli by fusing a bacterial signal peptide to the antibody's N-terminus (1,2). These findings allowed scientists to transfer the principles of the immune system for producing specific antibodies to a given antigen into a bacterial system (3). It was now possible to establish antibody libraries in E. coli that could be directly screened for binding to antigen. This was accomplished at first by transforming E coli with plasmids containing polymerase chain reaction (PCR)-amplified immunoglobulin families from the lymphocytes of immunized mice. Immunogen-reactive recombinant antibodies were then selected by an enzyme-linked immunosorbent assay (ELISA) of the bacterial supernatant from isolated bacterial colonies (4). This procedure was subsequently improved upon by inserting the antibody operon into bacteriophage λ. Antibody libraries were then able to be efficiently transfected into E. coli and plaque lift-offs of lysed bacterial colonies on nitrocellulose could be screened for reactivity to a radioactive labeled immunogen (5-7).
Collapse
|
138
|
Braunagel M, Little M. Construction of a semisynthetic antibody library using trinucleotide oligos. Nucleic Acids Res 1997; 25:4690-1. [PMID: 9358184 PMCID: PMC147064 DOI: 10.1093/nar/25.22.4690] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
A semisynthetic antibody library composed of single chain Fv fragments (scFv) was constructed by replacing the heavy chain CDR3 region of a human scFv by a random sequence of eight amino acids using trinucleotide codons. After cloning into a phage display vector, an antibody library was generated with a complexity of 8 x 10(8) independent clones. The library was screened for binders to dinitrophenol, fluorescein isothiocyanate and 3-nitro-4-hydroxy-5-iodophenylacetic acid. scFv antibodies that specifically bound the antigen were obtained in each case.
Collapse
|
139
|
Brocks B, Rode HJ, Klein M, Gerlach E, Dübel S, Little M, Pfizenmaier K, Moosmayer D. A TNF receptor antagonistic scFv, which is not secreted in mammalian cells, is expressed as a soluble mono- and bivalent scFv derivative in insect cells. IMMUNOTECHNOLOGY : AN INTERNATIONAL JOURNAL OF IMMUNOLOGICAL ENGINEERING 1997; 3:173-84. [PMID: 9358270 DOI: 10.1016/s1380-2933(97)00011-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Single chain antibodies (scFv) are usually produced in E. coli, but generation of certain scFv derivatives, such as complex fusion proteins or glycosylated forms of scFv is restricted to eukaryotic expression systems. We investigated the production of soluble mono- and bivalent single chain antibodies (scFv) in eukaryotic cells and describe a cassette vector system for mammalian and baculovirus expression which is compatible with an established vector system for bacterial expression and phage display selection of scFvs. The applied model scFv was derived from a murine antibody (H398) against human tumor necrosis factor receptor 1 (TNFR60), known to be a potent antagonist of TNF action in its monomeric form and a potential therapeutic agent for treatment of TNF-mediated diseases. Surprisingly, the monomeric scFv form of H398 (scFv H398) is expressed but not secreted in different mammalian cells. In contrast, in insect cells using recombinant baculovirus, a monovalent scFv H398 and a bivalent scFv fusion protein with an human IgG1 Fc region were expressed and secreted with correctly processed signal sequence. Concerning the influence of valency of the model Ab and its derivatives on antigen binding affinity and neutralisation of TNF activity, we found that the mono- and bivalent form of scFv H398 possesses the same characteristics as proteolytically produced Fab H398 and original mAb H398, respectively. Furthermore, fusion of the Ig Fc protein to scFv H398 increase the in vitro half-life at 37 degrees C. We conclude that the described cassette vectors readily allow the eukaryotic expression of mono- and bivalent scFv derivatives to analyse the influence of valency of scFv molecules on antigen binding and biological activity.
Collapse
|
140
|
Dörsam H, Rohrbach P, Kürschner T, Kipriyanov S, Renner S, Braunagel M, Welschof M, Little M. Antibodies to steroids from a small human naive IgM library. FEBS Lett 1997; 414:7-13. [PMID: 9305722 DOI: 10.1016/s0014-5793(97)00966-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Human antibodies specific for digoxigenin, estradiol, testosterone and progesterone have been isolated from a small combinatorial IgM repertoire (4 x 10(7)) of single chain antibodies (scFv). The affinities of both the anti-estradiol and antiprogesterone scFv were approximately 10(8) M(-1). Naive IgM genes appeared to be highly represented, since only the heavy chain variable domain of the anti estradiol antibody contained differences to corresponding germline sequences. The light chain variable domain of the progesterone receptor was also identical to a germline sequence, showing that it is possible for completely naive antibodies to bind steroids with affinities comparable to those obtained after a secondary immune response.
Collapse
|
141
|
Law MH, Algar E, Little M. Allelic imbalance at chromosome 1q21 in Wilms tumor. CANCER GENETICS AND CYTOGENETICS 1997; 97:54-9. [PMID: 9242218 DOI: 10.1016/s0165-4608(96)00342-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The Wilms tumor suppressor gene 1, WT1, located on chromosome 11p13 is mutated in only a subset of Wilms tumors. Cytogenetic studies of Wilms tumors show that the most frequent structural anomalies after those affecting chromosome 11p are rearrangements of 1q, suggesting that there is a gene involved in Wilms tumor etiology in this region. The WT1 target sequence +P5 (D1S3309E), isolated using whole-genome polymerase chain reaction (PCR), binds all WT1 isoforms in vitro and has been mapped to 1q21-22. As +P5 may mark a 1q Wilms tumor gene, constitutional and tumor DNA from 33 Wilms tumor patients (36 tumors) was screened for allele imbalance using microsatellite markers from 1p21 to 1q44. Although no gross rearrangements of the +P5 region were found, this study demonstrates allele imbalance for 1q in 12% of patients (5/36 tumors), defining a smallest region of overlap at 1q21. This finding supports a role for 1q21 in Wilms tumorigenesis.
Collapse
|
142
|
Terness P, Welschof M, Moldenhauer G, Jung M, Moroder L, Kirchhoff F, Kipriyanov S, Little M, Opelz G. Idiotypic vaccine for treatment of human B-cell lymphoma. Construction of IgG variable regions from single malignant B cells. Hum Immunol 1997; 56:17-27. [PMID: 9455490 DOI: 10.1016/s0198-8859(97)00145-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Immunoglobulin idiotypes (Id) of malignant B cells represent highly specific markers which can be used for vaccination. PCR-amplification of immunoglobulin genes enables the rapid production of large amounts of Id vaccines. However, the separate amplification and subsequent recombination of heavy and light chains can lead to a loss of the relevant Id. To preserve the original chain pairs, we used single malignant B cells derived from an immunocytoma patient. Cytoplasm was extracted and the mRNA transcribed into cDNA. The VH and VL genes were then amplified by PCR and cloned into a vector for expression in E. coli. Id production was checked using an anti-Id mouse monoclonal Ab raised against the patient's tumor-specific IgG. One out of 3 constructs expressed the relevant Id. Analysis of the first 31 light chain residues revealed an identical sequence for the malignant B cells' IgG and the recombinant Id construct. Exchange of either the heavy or light chain with an unrelated chain resulted in loss of the Id. An unrelated sequence derived from the c-myc protein is coupled to the Id vaccine. The lymphoma patient was shown to have Abs to the c-myc sequence. This sequence therefore, increases the Id+ Ab's antigenicity. CD spectroscopy showed an alpha-helical structure for the c-myc epitope. In conclusion, a B-cell lymphoma autovaccine was produced containing immunogenic sequences that do not alter the steric conformation of the tumor-specific Id.
Collapse
|
143
|
Fuchs P, Breitling F, Little M, Dübel S. Primary structure and functional scFv antibody expression of an antibody against the human protooncogen c-myc. Hybridoma (Larchmt) 1997; 16:227-33. [PMID: 9219032 DOI: 10.1089/hyb.1997.16.227] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The immunoglobulin heavy- and light-chain variable region (Vh and Vl) genes were isolated from Myc1-9E10 hybridoma cells, which secreted monoclonal antibody against human oncogen c-myc. The expression vector pOPE52-c-myc was constructed for the recombinant production in E. coli. A 30 kDa single chain fragment (scFv) expression product was found in the periplasmic space by SDS-PAGE and immunoblotting. A significant fraction was processed correctly as demonstrated with an antiserum recognizing the processed aminoterminus only. The specific binding of the scFv fragment to the peptide epitope of the maternal monoclonal antibody was demonstrated and the primary sequence of the variable regions was determined. Sequence comparison with previously published partial Vh and Vl sequences from this hybridoma cell line revealed a genetic heterogeneity for the light chain variable region. The potential use of this scFv as a new tool for detection and purification of tagged proteins, for adding costimulatory signals to the surface of cancer cells as well as for analyzing c-myc function in the living cell by cytoplasmic expression is discussed.
Collapse
|
144
|
Zewe M, Rybak SM, Dübel S, Coy JF, Welschof M, Newton DL, Little M. Cloning and cytotoxicity of a human pancreatic RNase immunofusion. IMMUNOTECHNOLOGY : AN INTERNATIONAL JOURNAL OF IMMUNOLOGICAL ENGINEERING 1997; 3:127-36. [PMID: 9237097 DOI: 10.1016/s1380-2933(97)00070-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Immunotoxins based on plant and bacterial proteins are usually very immunogenic. Human ribonucleases could provide an alternative basis for the construction of less immunogenic reagents. Two members of the human RNase family, angiogenin and eosinophil-derived neurotoxin (EDN), have been fused to a single chain antibody against the transferrin receptor, which is known to be internalised by endocytosis. The fusion proteins proved to be very efficient inhibitors of protein synthesis using various cell lines. It is not yet known whether the side effects of angiogenin and EDN will compromise their potential use as immunotoxins. OBJECTIVES The goal of this work was to construct a human immunotoxin with no harmful side effects. Bovine pancreatic ribonuclease has been shown to be as potent as ricin at abolishing protein synthesis on injection into oocytes. We therefore decided to clone its human analogue, which is fairly ubiquitous and per se non-toxic. An immunofusion of human pancreatic RNase with a single chain antibody against the transferrin receptor was tested for its ability to inhibit protein synthesis in three different human tumor cell lines. STUDY DESIGN DNA coding for the human pancreatic RNase was cloned partially from a human fetal brain cDNA library and then completed by PCR using a human placental cDNA library as a template. The RNase gene was then fused with a DNA coding for an single chain antibody against the transferrin receptor (CD71). After expressing the fusion protein in E. coli, the gene product was isolated from inclusion bodies and tested for cytotoxicity. RESULTS This fusion protein inhibited the protein synthesis of three human tumor cell lines derived from a melanoma, a renal carcinoma and a breast carcinoma, with IC50s of 8, 5 and 10 nM, respectively. These values were comparable with those using a similar fusion protein constructed with eosinophil derived neurotoxin (EDN) as the toxic moiety (IC50s of 8, 1.2 and 3 nM, respectively). The slightly lower activities of the human pancreatic RNase-scFv (pancRNase-scFv) with two of the cell lines suggests that fewer molecules are reaching the cytoplasmic compartment, since it was twice as active as EDN-scFv in inhibiting the protein synthesis of a rabbit reticulocyte lysate. CONCLUSION These results demonstrate that the human pancreatic RNase, which is expected to have a very low immunogenic potential in humans with no inherent toxicity, may be a potent cytotoxin for tumor cells after antibody targeting.
Collapse
|
145
|
Terness P, Welschof M, Kohl I, Moroder L, Navolan D, Dufter C, Little M, Opelz G. Epitope mapping and gene structure analysis of a human immunosuppressive natural IgG-anti-IgG autoantibody. Immunol Lett 1997. [DOI: 10.1016/s0165-2478(97)86490-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
146
|
Holmes G, Boterashvili S, English M, Wainwright B, Licht J, Little M. Two N-terminal self-association domains are required for the dominant negative transcriptional activity of WT1 Denys-Drash mutant proteins. Biochem Biophys Res Commun 1997; 233:723-8. [PMID: 9168922 DOI: 10.1006/bbrc.1997.6545] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Patients with Denys-Drash syndrome (DDS) have been shown to be constitutionally heterozygous for mutations of the WT1 gene. Almost all DDS mutations inactivate or remove the DNA-binding zinc finger region of WT1 and the resulting mutant proteins appear to act in a dominant negative manner. This may occur via WT1 self-association, which has been shown to involve the first 180 amino acids. By creating a series of N-terminal deletions, we have further investigated WT1 self-association using a yeast di-hybrid system and an in vitro protein binding assay. Our results suggest that there are two distinct domains within the N-terminal region facilitating self-association, residing from amino acids 1-45 and 157-253. Co-transfection of WT1 with progressively shorter N-terminal constructs demonstrates that both of these sites are required for a dominant negative activity as assessed by activation of a reporter construct.
Collapse
|
147
|
Kipriyanov SM, Moldenhauer G, Martin AC, Kupriyanova OA, Little M. Two amino acid mutations in an anti-human CD3 single chain Fv antibody fragment that affect the yield on bacterial secretion but not the affinity. PROTEIN ENGINEERING 1997; 10:445-53. [PMID: 9194170 DOI: 10.1093/protein/10.4.445] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Recombinant antibody fragments directed against cell surface antigens have facilitated the development of novel therapeutic agents. As a first step in the creation of cytotoxic immunoconjugates, we constructed a single-chain Fv fragment derived from the murine hybridoma OKT3, that recognizes an epitope on the epsilon-subunit of the human CD3 complex. Two amino acid residues were identified that are critical for the high level production of this scFv in Escherichia coli. First, the substitution of glutamic acid encoded by a PCR primer at position 6 of VH framework 1 by glutamine led to a more than a 30-fold increase in the production of soluble scFv. Second, the substitution of cysteine by a serine in the middle of CDR-H3 additionally doubled the yield of soluble antibody fragment without any adverse effect on its affinity for the CD3 antigen. The double mutant scFv (Q,S) proved to be very stable in vitro: no loss of activity was observed after storage for 1 month at 4 degrees C, while the activity of scFv containing a cysteine residue in CDR-H3 decreased by more than half. The results of production yield, affinity, stability measurements and analysis of three-dimensional models of the structure suggest that the sixth amino acid influences the correct folding of the VH domain, presumably by affecting a folding intermediate, but has no effect on antigen binding.
Collapse
|
148
|
Welschof M, Terness P, Kipriyanov SM, Stanescu D, Breitling F, Dörsam H, Dübel S, Little M, Opelz G. The antigen-binding domain of a human IgG-anti-F(ab')2 autoantibody. Proc Natl Acad Sci U S A 1997; 94:1902-7. [PMID: 9050877 PMCID: PMC20015 DOI: 10.1073/pnas.94.5.1902] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Recent studies revealed an immunoregulatory role of natural IgG-anti-F(ab')2 antibodies in both healthy individuals and patients with certain diseases. The implication of anti-F(ab')2 antibodies in the pathogenesis of diseases prompted us to study the gene segment structure of their antigen-binding domains and their binding characteristics. cDNA was prepared from the lymphocytes of a patient with a high IgG-anti-F(ab')2 serum titer. Variable heavy and light gene segments were amplified by PCR and inserted into a phagemid surface expression vector. Single-chain antibodies displayed on the phage surface were screened for binding to F(ab')2 fragments. The subsequent analysis of 95 single clones demonstrated that they all bound specifically to F(ab')2. Sequence analyses of 12 clones showed that 11 were identical and 1 contained a silent point mutation in the heavy chain and three amino acid exchanges in the light chain. The heavy chains belonged to the V(H)3 and the light chains to the V(kappa)2 gene family. The 11 identical light-chain genes were completely homologous to a germ-line sequence (DPK-15). Binding assays showed that the single-chain antibodies bind to F(ab')2, but not to Fab, Fc, or intact IgG. This binding pattern was confirmed by surface plasmon resonance studies, which revealed a relatively high affinity (Ka = 2.8 x 10(7) M(-1)). The strong binding capacity was further demonstrated by competitive inhibition of the serum anti-IgG antibody's interaction with antigen. The present study defines for the first time to our knowledge the gene segment structure of the antigen-binding domain of two human IgG-anti-F(ab')2 autoantibody clones and describes the binding kinetics of the purified monomeric fragments.
Collapse
|
149
|
Kipriyanov SM, Moldenhauer G, Little M. High level production of soluble single chain antibodies in small-scale Escherichia coli cultures. J Immunol Methods 1997; 200:69-77. [PMID: 9005945 DOI: 10.1016/s0022-1759(96)00188-3] [Citation(s) in RCA: 149] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We have investigated the effect of growth and induction conditions on the production of soluble single-chain Fv antibody fragments in Escherichia coli under the control of wt lac promoter. The scFv was directed into the periplasmic space by a pelB leader sequence. Addition of sucrose to the medium gave a 15-25-fold increase in the yield of soluble scFv-phOx (3.0 mg/l) for bacterial shake-tube cultures and an increase of 80-150-fold (16.5 mg/l) for shake-flask cultures. Using flask culture in the presence of 0.4 M sucrose, a significant amount of scFv was released into the medium. We found that the scFv could be made to accumulate in the periplasm or be secreted into the medium by simply changing the incubation conditions and the concentration of the inducer. The ratio between soluble antibody fragments and insoluble scFv aggregates proved to be dependent on the strength of the promoter. Lowering the incubation temperature below 20 degrees C had no effect on the yield of soluble antibody fragments in the periplasm, but they were no longer secreted into the medium. An example of high level production in shake-flask cultures and one-step purification by immobilized metal affinity chromatography (IMAC) is described for a soluble scFv specific for the T cell surface antigen CD3. The biological activity of the purified anti-CD3 scFv was demonstrated by flow cytometry. This method should be especially useful for the functional screening of a large number of clones in small-scale cultures.
Collapse
|
150
|
Kipriyanov SM, Little M. Affinity purification of tagged recombinant proteins using immobilized single chain Fv fragments. Anal Biochem 1997; 244:189-91. [PMID: 9025933 DOI: 10.1006/abio.1996.9918] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
|