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Biomedical subjects

W Strittmatter

Publications and source records attributed to W Strittmatter.

At least 19 recordsLinked to original sources
PubMed1998

The first constant domain (C(H)1 and C(L)) of an antibody used as heterodimerization domain for bispecific miniantibodies.

Bispecific miniantibodies were constructed by genetically fusing the C(H)1 domain of an IgG1 to the C-terminus of a single-chain Fv fragment (scFv-425), specific for the EGF receptor, and fusing the C(L) domain of a kappa light chain to the C-terminus of a scFv specific for CD2 (scFv-M1). An efficient dicistronic gene arrangement for functional expression in Escherichia coli was constructed. Immunoblots demonstrated correct domain assembly and the formation of the natural C(H)1-C(L) disulfide bridge. Gel filtration confirmed the correct size, sandwich ELISAs demonstrated bispecific functionality, and SPR biosensor measurements determined binding to EGF-R in comparison to bivalent constructs. Bispecific anti-EGF-R/anti-CD2 miniantibodies are candidates for the immunotherapy of cancer.

Amino Acid Sequence↗
PubMed1996

A fusion protein of IL-8 and a Fab antibody fragments binds to IL-8 receptors and induces neutrophil activation.

A fusion protein was generated by genetic engineering which combined a Fab fragment of a monoclonal antibody directed to the human epidermal growth factor receptor with the biologically active N-terminally truncated 2-72 amino acid form of the human chemokine IL-8. The Fab IL-8 fusion protein was expressed in E. coli and antibody binding and IL-8 activity were determined. Our data indicate that the N-terminus of IL-8 remains functional for receptor interaction. The fusion protein showed specific binding to IL-8 receptors, induced IL-8 mediated chemotactic activity, and the release of MPO activity. However, N-terminal fusion of IL-8 to the carboxyl terminus of the Fab fragment resulted in reduced binding to IL-8 receptors and consequently to reduced biologic activity of IL-8. The affinity of the antibody arm for EGF-R was improved when compared to a monovalent Fab. Fusion proteins as described herein may represent improved therapeutics for cancer therapy based on their potential to selectively increase and prolong cytokine concentration in the tumour. Since chemokines such as IL-8 recruit effector cells and stimulate effector cell function in situ, a lymphocyte-independent anti-tumour activity followed by tumour-specific immunity could be proposed.

Antibodies, Monoclonal↗
PubMed1996

High volumetric yields of functional dimeric miniantibodies in Escherichia coli, using an optimized expression vector and high-cell-density fermentation under non-limited growth conditions.

Functional bivalent miniantibodies, directed against the epidermal growth factor receptor, accumulated to more than 3 gl-1 in high-cell-density cultures of Escherichia coli RV308(pHKK) on a pilot scale. The miniantibodies consist of scFv fragments with a C-terminal hinge followed by a helix-turn-helix motif, which homodimerizes in vivo. The improved expression vector pHKK is characterized by the hoklsok suicide system, improving plasmid maintenance, and the inducible lac pl o promoter system with the very strong T7g10 Shine-Dalgarno sequence. The expression unit is flanked by terminators. The prototrophic RV308 cells were cultivated in glucose mineral salt medium and reached a cell density of 145 g dry biomass l-1 after 33 h. After induction, growth continued almost unchanged for a further 4 h with concomitant miniantibody formation. In the fedbatch phase, the concentration of glucose was kept almost constant at the physiological level of approximately 1.5 gl-1, using on-line flow injection analysis for control. Surprisingly, E. coli RV308(pHKK) did not accumulate significant amounts of the metabolic by-product acetate under these unlimited aerobic growth conditions.

Acetates↗
PubMed1996

Bifunctional NHS-BAT ester for antibody conjugation and stable technetium-99m labeling: conjugation chemistry, immunoreactivity and kit formulation.

UNLABELLED: Conjugation chemistry and kit formulated binding of the NHS ester of 6-(4'-(4"-carboxyphenoxy)butyl)-2, 10-dimercapto-2,10-dimethyl-4,8-diazaundecane (NHS-BAT ester) to monoclonal antibodies (MAbs) was investigated. The functionalities of the resulting BAT conjugated and 99mTc-labeled MAbs BW 431/26, MAb 425 and bispecific MDX210 (fragment construct) were tested by immunoreactivity and immunoscintigraphy. METHODS: The kinetics and chemistry of the conjugation reaction were monitored by high-performance liquid chromatography, size-exclusion chromatography and positive fast-atom-bombardment mass spectra (FAB-MS). The 99mTc BAT-MAbs were tested with various immunoreactivity assays. The biodistribution of 99mTc-BAT-BW 431/26 in rats was compared with directly labeled BW 431/26. RESULTS: At pH 8.5 and 25 degrees C, the reactivity of the NHS-BAT ester was high with 90% completion after 30 min. The conjugation yield of 19 microM MAb and 228 microM NHS-BAT ester amounted to 30%. Higher NHS-BAT ester concentrations afforded higher BAT-to-MAb ratios. According to FAB-MS, the conjugation competing hydrolysis surprisingly occurred at the NHS ring. Almost quantitative 99mTc labeling was achieved after 5 min at 25 degrees C. Immunoreactivity of the 99mTc-BAT antibodies showed > 90% recovery and proved to be insensitive to BAT-to-MAb ratios of up to 10. The 99mTc-BAT-BW 431/26 showed similar organ distribution but revealed less urinary excretion compared with the directly labeled BW 431/26. Immunoscintigraphy with 99mTc-labeled and BAT-BW 431/26 and BAT-MAb 425 showed the respective biological function in vivo. CONCLUSION: According to straightforward conjugation chemistry, the ease of 99mTc labeling and the application of a simple ultrafiltration technique, the NHS-BAT ester represents a nondestructive, universally applicable biofunctional ligand to introduce stable 99mTc protein binding sites. Kit formulated conjugation/labeling can be performed with little time requirements and laboratory experience.

Animals↗
PubMed1994

Induction of tumour cell lysis by a bispecific antibody recognising epidermal growth factor receptor (EGFR) and CD3.

A bispecific antibody construct (bAb) recognising CD3 and epidermal growth factor receptor (EGFR) was studied in vitro. Human peripheral blood lymphocytes (PBL), pre-activated with monoclonal antibody OKT-3 or with irradiated tumour cells, were armed with the bAb construct and targeted to autologous and allogeneic tumour target cells in culture. bAb EGFR x CD3 promoted significant cytolysis even at a concentration of 1 ng/ml. The specificity of target cell lysis was provided by the EGFR specificity of the bAb, as tumour cells negative for EGFR were not lysed. However, not only EGFR-positive tumour cells but also EGFR-positive normal cells were killed. Human renal cancer cell lines and the normal autologous kidney cell cultures expressing the same level of EGFR molecules were lysed to a similar extent. These results may contribute toward the planning of future clinical trials with such bAb.

Antibodies, Bispecific↗
PubMed1994

Complex genetic disease: can genetic strategies in Alzheimer's disease and new genetic mechanisms be applied to epilepsy?

Strategies used in molecular genetics have changed modern neurology. The gene or genes responsible for several major neurologic diseases have now been identified using "reverse" or positional genetics. Unexpected new genetic mechanisms have been discovered in human neurologic diseases, including (a) identical mutations of the prion protein gene in Creutzfeldt-Jakob disease and fatal familial insomnia with the phenotypic expression directed by an accompanying polymorphism; (b) stable duplications of chromosome 17 in Charcot-Marie-Tooth disease (type 1A) that involve many genes, only one of which appears to cause neuropathy; and (c) highly variable, dynamic mutations in myotonic dystrophy, fragile X syndrome, and Kennedy's syndrome that modulate variable expressivity in multiple tissues. There is growing recognition that neurologic diseases are often complex genetic diseases with multifactorial rather than simple modes of inheritance. For example, genetic association/linkage strategies have interacted with biochemistry and immunopathology studies to produce new insights into the disease mechanism of late-onset Alzheimer's disease. The role of apolipoprotein E in late-onset Alzheimer's disease is an example of how new analytical techniques of genetic disease can be applied to dissect multiple genes. Similar research strategies are suggested for the study of epilepsy as a complex disease.

Alleles↗
PubMed1993

Induction of tumor-cell lysis by bi-specific antibody recognizing ganglioside GD2 and T-cell antigen CD3.

Human tumor cells expressing ganglioside GD2 were lysed by various effector populations targeted with an anti-CD3-anti-GD2 bi-specific antibody (BAb CD3 x GD2). This antibody-heteroconjugate was prepared by chemically cross-linking the OKT-3 monoclonal antibody (MAb) reactive with CD3 antigen on T lymphocytes with the ganglioside MAb ME 361, which binds preferentially to the tumor-associated ganglioside GD2. The specificity of target-cell lysis by the cytotoxic T cells (CTL) was mediated by the specificity of the targeting antibody: GD2-negative cells were not lysed in the presence of the CD3 x GD2 BAb. A dose-dependent response was observed in a range of 10 to 10,000 ng/ml. In contrast, 2 other BAbs recognizing the tumor-associated antigens EGF-R and TKB-2 had greater potency to mediate tumor-cell lysis than the GD2 x CD3 BAb. Peripheral-blood cells (PBL) stimulated with OKT-3 MAb or with irradiated tumor cells in a mixed lymphocyte culture (MLTC) could be induced to lyse GD2-positive tumor cells in the presence of CD3 x GD2 BAb. The tumor-cell lysis could be mediated by autologous or allogeneic effector cells. NK cells had no influence on the BAb-induced cytotoxicity.

Antibodies↗
PubMed1988

Purification and characterization of eight class 5 outer membrane protein variants from a clone of Neisseria meningitidis serogroup A.

Methods published for the purification of P.II proteins from Neisseria gonorrhoea have been modified to allow the purification of class 5 proteins from Neisseria meningitidis serogroup A bacteria. The five class 5 protein electrophoretic variants detected within an epidemic in the Gambia (a, b, c, d, and e) and three other variants (f, g, and h) found within other isolates of the same clone in West Africa have been purified with yields of 6-28 mg. The NH2-terminal amino acid sequence for variant c differs from those of the other class 5 proteins, whereas the latter are very similar to the sequence predicted for two class 5 proteins from DNA analyses of serogroup C meningococci and determined for 8 P.II proteins from gonococci. Numerous other regulatory, chemical, and serological differences were found between the c protein and the other class 5 proteins such that we recommend that the class 5 proteins be subdivided into two subclasses. mAbs have been isolated that distinguish between these two protein subclasses and Western blotting with these antibodies enabled us to conclude that both protein subclasses were found in bacteria isolated from different epidemics and pandemics of the last 50 yr.

Amino Acid Sequence↗
PubMed1987

Characterisation of protein co-extracted together with LPS in Escherichia coli, Salmonella minnesota and Yersinia enterocolitica.

The porin proteins of Escherichia coli, Yersinia enterocolitica, and Salmonella minnesota were found to co-extract by the phenol-chloroform-petroleum ether method together with the R lipopolysaccharide of these strains. Lipopolysaccharide free protein recovered from the phenolic residue of the phenol-chloroform-petroleum ether extract migrated as a Mr 36-37,000 protein. We could demonstrate that the protein was extracted from bacteria as a high molecular weight protein-lipopolysaccharide complex. Once exposed to phenolic conditions, the protein was no longer soluble in the phenol-chloroform-petroleum ether extraction mixture, indicating a highly specific lipopolysaccharide-protein association.

Amino Acids↗
PubMed1986

Isolation and preliminary biochemical characterization of the gonococcal H.8 antigen.

We have presented a method for the extraction and isolation of the gonococcal H.8 antigen. There was no evidence of contamination by other gonococcal proteins, phospholipids, or LPS. The purified H.8 antigen was subjected to preliminary analysis and appeared to be a proteolipid consisting of both protein and lipid components. The amino acid composition was unusual; the peptide portion of the antigen was an alanine and proline-rich molecule that lacked aromatic and sulfur-containing amino acids. The overall amino acid composition is hydrophobic. A lipid constituent was also identified; it was made up of at least two lipid components, which were unique to the H.8 molecule. The chemical nature of the association of the protein and lipid is presently unknown, but it is clearly a tenacious one.

Amino Acids↗
PubMed1984

Fibrillation of a cardiac region and the tachycardia mode of a two-oscillator system.

The interaction between two nonlinear oscillators is discussed, each one representing a region of the heart and characterized by a specific type of phase transition curve (PTC) which has been derived from human ECG-recordings. Besides the normal conduction a tachycardia mode is studied where the excitation is reflected by each oscillator (reentry). It turns out that under specific physiologically plausible conditions this tachycardia mode cannot be terminated by an external stimulus. Under periodic stimulation the response of the tachycardia mode is chaotic. Within a sheet of nonlinear oscillators the tachycardia mode serves as an ectopic focus or a region of reentry which induces fibrillation of the whole tissue.

Arrhythmias, Cardiac↗
PubMed1983

Structural studies on the non-toxic lipid A from Rhodopseudomonas sphaeroides ATCC 17023.

The lipid A isolated from Rhodopseudomonas sphaeroides ATCC 17023 has been investigated. A sequence of analyses indicated beta-D-glucosaminyl-1,6-D-glucosamine as the sugar backbone carrying phosphate groups at C-1 of the reducing glucosamine and C-4 of the non-reducing glucosamine. Both 3-(7-tetradecenoyl)oxytetradecanoic and 3-oxotetradecanoic acid are linked to the NH2 groups. Two residues of 3-hydroxydecanoic acid are linked to hydroxy groups at C-3 of both reducing and non-reducing glucosamine, and the hydroxy group of 3-hydroxydecanoic acid is free. In free lipid A, the hydroxy group at C-4 of the reducing glucosamine and at C-6 of the non-reducing glucosamine are unsubstituted. The latter probably arises from a 3-deoxy-D-manno-octulosonate linkage. The structural similarities and dissimilarities existing between lipid A of R. sphaeroides, which is non-toxic, and lipid A types such as those from Salmonella, which are toxic, are discussed.

Chemical Phenomena↗
PubMed1983

Nontoxic lipopolysaccharide from Rhodopseudomonas sphaeroides ATCC 17023.

Chemical analysis of the lipopolysaccharide from Rhodopseudomonas sphaeroides ATCC 17023, isolated by the phenol-chloroform-petroleum ether method, revealed the presence of glucuronic acid, 2-keto-3-deoxyoctonate, threonine, and phosphorus in the polysaccharide moiety. The lipid A component contained glucosamine, glucosamine phosphate, amide-bound 3-oxotetradecanoic acid and 3-hydroxytetradecanoic acid, and ester-bound 3-hydroxydecanoic acid and 7-tetradecenoic acid. Structural similarity of the lipid A from R. sphaeroides ATCC 17023 to enterobacterial lipid A is indicated by the existence of a serological cross-reaction occurring between the lipid A from R. sphaeroides ATCC 17023 and that from Salmonella minnesota R595. The lipopolysaccharide and lipid A of R. sphaeroides, however, were found to be neither toxic in mice nor pyrogenic in rabbits.

Carbohydrates↗