In vivo methods for imaging blood-brain barrier function and dysfunction

The blood-brain barrier (BBB) is the interface between the central nervous system and systemic circulation. It tightly regulates what enters and is removed from the brain parenchyma and is fundamental in maintaining brain homeostasis. Increasingly, the BBB is recognised as having a significant role in numerous neurological disorders, ranging from acute disorders (traumatic brain injury, stroke, seizures) to chronic neurodegeneration (Alzheimer's disease, vascular dementia, small vessel disease). Numerous approaches have been developed to study the BBB in vitro, in vivo, and ex vivo. The complex multicellular structure and effects of disease are difficult to recreate accurately in vitro, and functional aspects of the BBB cannot be easily studied ex vivo. As such, the value of in vivo methods to study the intact BBB cannot be overstated. This review discusses the structure and function of the BBB and how these are affected in diseases. It then discusses in depth several established and novel methods for imaging the BBB in vivo, with a focus on MRI, nuclear imaging, and high-resolution intravital fluorescence microscopy.

Identification and Phylogenetic analysis of thermophilic sulfate-reducing bacteria in oil field samples by 16S rDNA gene cloning and sequencing

Thermophilic sulfate-reducing bacteria (SRB) have been recognized as an important source of hydrogen sulfide (H2S) in hydrocarbon reservoirs and in production systems. Four thermophilic SRB enrichment cultures from three different oil field samples (sandstone core, drilling mud, and production water) were investigated using 16S rDNA sequence comparative analysis. In total, 15 different clones were identified. We found spore-forming, low G+C content, thermophilic, sulfate-reducing Desulfotomaculum-related sequences present in all oil field samples, and additionally a clone originating from sandstone core which was assigned to the mesophilic Desulfomicrobium group. Furthermore, three clones related to Gram-positive, non-sulfate-reducing Thermoanaerobacter species and four clones close to Clostridium thermocopriae were found in enrichment cultures from sandstone core and from production water, respectively. In addition, the deeply rooted lineage of two of the clones suggested previously undescribed, Gram-positive, low G+C content, thermophilic, obligately anaerobic bacteria present in production water. Such thermophilic, non-sulfate-reducing microorganisms may play an important ecological role alongside SRB in oil field environments.

The isolation of super-sensitive anti-hapten antibodies from combinatorial antibody libraries derived from sheep

The complexity and expense of producing anti-hapten monoclonals via the traditional hybridoma route and the preferential selection of antibodies that recognise the conjugated form of the hapten, over antibodies that specifically recognise free hapten, are two of the more important problems that have limited the development and application of anti-hapten antibodies. The advent of phage display technology allows the rapid isolation of monoclonal antibody fragments from libraries of different antibodies (>10(8)) displayed on the surface of filamentous bacteriophages. Much of the power of this new approach lies in the flexibility with which these libraries can be screened for suitable binders. Using an optimised selection procedure, we have isolated from a sheep antibody phage display library, super-sensitive anti-hapten antibodies specific for the herbicide and environmental pollutant, atrazine. In particular, two phage clones have been isolated that can be expressed cheaply and in quantity in Escherichia coli, demonstrate excellent stability in nonphysiological conditions and are exciting prospects for immunoassay applications including ELISA, dip-stick formats, on-line monitoring and biosensor technologies. In ELISA formats they show low levels of cross reactivity with related molecules and a limit of detection of a 1-2 parts per trillion (p.p.t.), well within the 100 p.p.t. required by EC legislation.

Multimeric humanized varicella-zoster virus antibody fragments to gH neutralize virus while monomeric fragments do not

Murine monoclonal antibody 206 (MAb mu206) binds to gH, the varicella-zoster virus (VZV) fusogen, neutralizing the virus in vitro in the absence of complement and inhibiting cell-to-cell spread and egress of VZV in cultured cells. We have humanized this antibody to generate MAb hu206 by complementarity determining region grafting. MAb hu206 retained binding and in vitro neutralizing activity, as well as cross-reactivity with ten different VZV strains. Single-chain antibody fragments (scAb) derived from MAb hu206 were produced in Escherichia coli. These scAb retained the binding properties of the whole antibody. However, monomeric scAb exhibited markedly reduced neutralizing activity compared to the bivalent parental MAb hu206. Shortening the peptide linker joining the V(H) to the V(kappa) domain from 14 to 5 or even 0 residues encouraged multimerization and increased neutralizing efficacy. The fact that Fab fragments enzymatically generated from whole MAb hu206 lost their neutralizing potency lent support to the proposal that valency is important for VZV neutralization at this epitope.

Relationship between follicle size and gonadotrophin surge attenuating factor (GnSAF) bioactivity during spontaneous cycles in women

BACKGROUND

We have previously demonstrated that follicles < or =11 mm diameter from women undergoing IVF contain higher concentrations of gonadotrophin surge attenuating factor (GnSAF) bioactivity than large follicles from the same ovaries.

METHODS

To determine whether this finding is relevant to spontaneous cycles, follicular fluid aspirated from 37 follicles between 3 and 25 mm in diameter from 14 pairs of ovaries from regularly cycling women undergoing total abdominal hysterectomy and bilateral salpingoophorectomy for benign gynaecological disease was pooled into size categories (3 + 4, 5 + 6, 7 + 8, 9 + 10, 11 + 12, 14 + 15, 18 and 25 mm). These pools were bioassayed for GnSAF and inhibin-A, inhibin-B and activin-A concentrations were determined.

RESULTS

Follicles of 5 + 6 mm diameter contained the highest concentrations of GnSAF bioactivity (reducing GnRH-induced LH secretion to 38 +/- 8% of control, P < 0.001), while those of 25 mm diameter contained one quarter of this concentration (reducing GnRH-induced LH secretion to 72 +/- 2% of control, P < 0.05). GnSAF bioactivity was closely related to follicle size (r = -0.836, P < 0.01), but not to inhibin-A, inhibin-B or activin-A concentrations.

CONCLUSIONS

The finding that small follicles contain high concentrations of GnSAF bioactivity, which fall as folliculogenesis progresses during spontaneous cycles, support the hypothesis that GnSAF has a role in preventing the premature onset of the LH surge in women.

Construction, production, and characterization of humanized anti-Lewis Y monoclonal antibody 3S193 for targeted immunotherapy of solid tumors

The Lewis Y (Ley) antigen is a blood group-related antigen that is expressed in a high proportion of epithelial cancers (including breast, colon, ovary, and lung cancer) and is an attractive target for monoclonal antibody-directed therapy. The murine monoclonal 3S193 (IgG3) was generated in BALB/c mice by immunization with Ley-expressing cells of the MCF-7 breast carcinoma cell-line. The murine 3S193 showed high specificity for Ley in ELISA tests with synthetic Ley and Ley-containing glycoproteins and glycolipids and also reacted strongly in rosetting assays and cytotoxic tests with Ley-expressing cells. We generated a humanized form of the murine 3S193 antibody by linking cDNA sequences encoding the variable region of murine 3S913 with frameworks of the human KOL heavy chain and REI K chain. The genes for the humanized 3S193 monoclonal antibody IgG1 were transfected into mouse myeloma NS0 cells and cloned for the establishment of high antibody-producing colonies. Humanized 3S193 antibody was subsequently produced through in vitro culture and under good manufacturing practice conditions using hollow-fiber bioreactors. The purified humanized 3S193 (hu3S193) was subsequently characterized and validated for use in preliminary immunotherapy investigations. hu3S193 reacted specifically with Ley antigen, with similar avidity to the murine form. hu3S193 demonstrated potent immune effector function, with higher antibody-dependent cell-mediated cytotoxicity than its murine counterpart and potent complement-dependent cytotoxicity (ED50, 1.0 microg/ml). The in vivo immunotherapeutic potential of hu3S193 was assessed in a human breast xenograft model using MCF-7, Ley-positive cells. Six i.v. doses of up to 1 mg of hu3S193 were administered to animals bearing established tumors (120-130 mm3) with no significant effect on tumor growth. In contrast, in an MCF-7 xenograft preventive model, a 1-mg hu3S193 dosage schedule was able to significantly slow tumor growth compared with placebo and isotype-matched control IgG1 antibody. hu3S193 has promise for immunotherapy of Ley-positive tumors and is currently entering Phase I clinical trials.

Analysis of the diversity of a sheep antibody repertoire as revealed from a bacteriophage display library

We have applied bacteriophage display technology to construct and analyze the diversity of an IgG library of >1 x 108 clones from an adult sheep immunized against the hapten atrazine. We have identified eight new VH gene families (VH2-VH9) and five new Vkappa gene families (VkappaV-VkappaIX). The heavy and kappa light chain variable region gene loci were found to be far more diverse than previously thought.

Cloning and expression of single chain antibody fragments in Escherichia coli and Pichia pastoris

The potential of recombinant antibody fragments is likely to be fulfilled only if they can be produced routinely at high concentrations. We have compared the ability of Escherichia coli and Pichia pastoris to produce functional recombinant single chain antibody (scAb) fragments. Two scAb fragments were expressed, an antihuman type V acid phosphatase (TRAP) and an anti-Pseudomonas aeruginosa lipoprotein I. We report here that, while expression from P. pastoris resulted in a significantly increased level of expression of the anti-TRAP scAb compared to E. coli, neither fragment was able to bind its target antigen as well as the bacterial product.

Reduced toxicity of expression, in Escherichia coli, of antipollutant antibody fragments and their use as sensitive diagnostic molecules

Single-chain antibody fragments (scAb), specific for the chlorophenoxy acid herbicide mecoprop, have been expressed and purified from the bacterium Escherichia coli. Co-expression with the colE1-compatible, arabinose-inducible, skp expression vector pHELP1 prevented bacterial lysis and significantly increased both total and functional expression yield. The periplasmic protein, SKP, may have a role as a generic detoxification protein. Surface plasmon resonance (BIAcore 2000) analysis confirmed that the purified scAb retained similar binding kinetics to the monoclonal antibody (Mab) from which it was cloned. In competition ELISA, the bacterial scAb showed the same specificity for mecoprop and a related herbicide, MCPA, as the Mab but an increase in sensitivity for free antigen in all ELISA formats. Bacterially expressed antibody fragments provide a simple, sensitive and cost-effective alternative to the traditional production of diagnostic Mabs via tissue culture.

Escherichia coli skp chaperone coexpression improves solubility and phage display of single-chain antibody fragments

Expression of single-chain antibody fragments (scAb)in the periplasm of Escherichia coli often results in low soluble product yield and cell lysis. We have increased scAb solubility and prevented cell culture lysis by coexpressing the E. coli Skp chaperone gene. A mutant Skp cistron was linked to a bacteriophage T7 gene 10 translational initiation region and placed either downstream of a scAb gene within an isopropyl beta-d-thiogalactopyranoside-inducible expression cassette or on a separate colE1-compatible arabinose-inducible vector. Increases in scAb solubility reflected the amount of coexpressed Skp. A bacteriophage display vector that was also engineered to coexpress Skp permitted display of a virtually undisplayable scAb and should prove useful in expanding library sizes.

Comparative sensitivity of immunoassays for haptens using monomeric and dimeric antibody fragments

A single-chain anti-atrazine antibody fragment, scAb (single-chain Fv with a CK domain), was expressed in Escherichia coli, and monomeric and dimeric species were preferentially purified from periplasmic extracts by chromatography upon nickel chelate immunosorbent columns or by immunoaffinity purification using a constant domain (CK) tag. Recombinant monomeric and dimeric antibody fragments, Fab, and intact monoclonal antibodies were compared in assays by competition between free atrazine in solution and (a) immobilized atrazine-bovine serum albumin conjugate (indirect assay) or (b) atrazine-alkaline phosphatase (direct assay). Recombinant antibody fragments provided a lower detection limit than either Fab or intact monoclonal antibody in both assay formats. Monomeric fragments displayed a sensitivity of detection down to 0.1 ppb, compared to 1.0 ppb for dimeric fragments and the parental monoclonal.

Production of a functional single chain antibody attached to the surface of a plant virus

A potato virus X (PVX) vector was used to express a single chain antibody fragment (scFv) against the herbicide diuron, as a fusion to the viral coat protein. The modified virus accumulated in inoculated Nicotiana clevelandii plants and assembled to give virus particles carrying the antibody fragment. Electron microscopy was used to show that virus particles from infected leaf sap were specifically trapped on grids coated with a diuron-BSA conjugate. The results demonstrate that the PVX vector can be used as a presentation system for functional scFv.

Differential efficiency of expression of humanized antibodies in transient transfected mammalian cells

Transient transfections are commonly used in the preliminary assessment of comparative levels of expression, biologic activity, and affinity of recombinant antibody molecules, but apparent expression levels can vary up to 200-fold. We have compared the expression levels of various humanized antibodies and "mixed and matched" heavy and light chains in transiently transfected CHO cells using replicate, small-scale transfections within single or replicate experiments to control for variation in transfection efficiency. We have found that each antibody is expressed with a characteristic efficiency, determined by a combination of factors including the level of light-chain synthesis, heavy- and light-chain "compatibility," and CDR/framework interactions to provide a compact Fv module.

Retention of neutralising activity by recombinant anti-pneumolysin antibody fragments

The variable domains of a neutralising (prevents erythrocyte lysis) anti-pneumolysin monoclonal antibody have been cloned and expressed as functional protein in Escherichia coli. Purification of the anti-pneumolysin single-chain antibody fragment, via antibody-affinity or metal-chelate affinity chromatography, resulted in product that was predominantly in a dimeric or monomeric form, respectively. The dimeric single-chain antibody fragment showed a higher sensitivity and affinity for immobilised antigen in both ELISA and BIAcore studies. The dimeric single-chain antibody fragment was as effective at protecting erythrocytes from lysis as the parent monoclonal. The monomeric, low affinity single-chain antibody fragment, showed reduced neutralising potency. As antibiotic resistant Streptococcus pneumoniae strains continue to show an increasing word-wide distribution, recombinant, neutralising antibody fragments, may provide an additional class of molecules useful in the treatment of toxaemia.

Colorimetric method for detecting amplified nucleic acids

Methods for detecting and measuring the success of nucleic acid sequence amplifications can be developed by detecting the by-products of amplification procedures. One method includes the detection of inorganic phosphate (Pi) during or on completion of the PCR. The method requires modification of assay conditions to prevent thermal- and template-independent enzymatic activity from nonspecifically hydrolyzing dNTPs. Detection of Pi by the traditional Fiske-SubbaRow method provides a sensitivity similar to ethidium bromide staining of amplified products. The method offers a simple and rapid assay for amplified nucleic acids and can be useful in assays where confirmation of the amplified DNA product is not essential.

Binding characteristics of anti-atrazine monoclonal antibodies and their fragments synthesised in bacteria and plants

Single-chain antibody fragments (scAb), specific for the herbicide atrazine, have been expressed in the bacterium Escherichia coli and in transgenic tobacco plants. The scAb could be purified as a monomer (monovalent) via a hexa-histidine tail or as a dimer (divalent) by antibody affinity chromatography. In competition ELISA, the bacterial scAb showed the same specificity for atrazine and related triazine herbicides as the parental mAb cell line, but both plant and bacterial monomeric scAbs showed increased sensitivity to free atrazine. Surface plasmon resonance (BIAcore 2000) analysis confirmed that purified scAb, derived from plant or bacteria, retained similar association rates as the mAb. However, the monomeric plant and bacterial scAbs showed a lower affinity for immobilised antigen, than the equivalent dimeric scAbs or mAb. This decrease in affinity was due to a 10 fold slower dissociation rate and is likely due to loss of the avidity contribution of dimeric molecules.

Stabilization of antibody fragments in adverse environments

Antibody fragments have the potential to be used as sensitive and specific binding agents in a broad range of industrial applications. Genetic manipulation has been used to design a series of antibody fragment configurations with a flexible linker and/or a disulphide bond between the heavy chain and light chain of an antibody fragment against the herbicide atrazine. The thermostability and stability to a range of denaturants, polar and non-polar solvents, surfactants and proteases have been compared. It has been found that a novel antibody fragment construct (STAB: stabilized antibody) containing both a flexible linker and a disulphide bond can be effectively produced and shows greatly improved stability in these diverse environments. These STABs should be useful in environmental diagnostics and remediation, and may provide a generic approach for stabilizing antibody fragments in formulations containing detergents and penetrants for topical application in the pharmaceutical and cosmetic industries.

The use of alkaline phosphatase-labelled oligonucleotide probes as culture confirmation reagents for identification of commercially important bacteria

A range of rRNA-targeted alkaline phosphatase labelled oligonucleotide probes was tested for use as culture confirmation reagents for the rapid identification of micro-organisms. The probes were specific to clinically important bacteria (Helicobacter pylori and Mycobacterium tuberculosis), fish and shellfish pathogens (Renibacterium salmoninarum and Vibrio vulnificus), food spoilage bacteria (Listeria spp. and L. monocytogenes), for bacteria of biotechnological importance (Streptomyces spp.) and for bacteria associated with the oil industry (Sulphate-reducing bacteria, SRB). A universal bacterial probe and a eukaryotic probe were included in the study as positive and negative controls, respectively. A total of 93 bacterial strains was screened. With the exception of a large number of cross-reactions of the SRB probe (specificity value of 29.4%) and a single cross-reaction of the R. salmoninarum probe (specificity value of 97.7%), dot blot analysis indicated that each probe hybridized 100% specifically to the organisms tested. A simple culture confirmation method was then developed using these probes to enable the identification of bacterial colonies using a simple hybridization procedure.

Expression and characterisation of single-chain antibody fragments produced in transgenic plants against the organic herbicides atrazine and paraquat

Single-chain antibody fragments (scAbs), which have a human C-kappa constant domain and a hexa-histidine tail attached to the carboxy terminus of the single-chain Fv (ScFv) fragments to facilitate purification, have been raised against the herbicides paraquat and atrazine and expressed in transgenic Nicotiana tabacum cv. Samsun NN. Prior to purification, the anti-atrazine scAb is expressed as up to 0.014% of soluble leaf protein and has a binding profile in ELISA, against an atrazine-bovine serum albumin (BSA) conjugate, similar to that of the scAb produced in Escherichia coli. Competition ELISA has shown that the plant-derived scAb also recognises free atrazine. Following antibody affinity purification to isolate dimers, the affinity for immobilised antigen approaches that of the parental monoclonal antibody. This was confirmed by surface plasmon resonance analysis. The purified scAb also recognises related triazine herbicides. When isolated from cell-suspension cultures, the anti-paraquat scAb binds to a paraquat conjugate in a concentration-dependent manner, with a profile similar to the parental monoclonal antibody. This is the first demonstration that functional scAbs against organic pollutants can be produced in transgenic plants and that the scAbs may be appropriate for the development of immunoassay-based detection systems.

The herpes simplex virus type 1 U(L)17 gene encodes virion tegument proteins that are required for cleavage and packaging of viral DNA

Previous studies have suggested that the U(L)17 gene of herpes simplex virus type 1 (HSV-1) is essential for virus replication. In this study, viral mutants incorporating either a lacZ expression cassette in place of 1,490 bp of the 2,109-bp U(L)17 open reading frame [HSV-1(deltaU(L)17)] or a DNA oligomer containing an in-frame stop codon inserted 778 bp from the 5' end of the U(L)17 open reading frame [HSV-1(U(L)17-stop)] were plaque purified on engineered cell lines containing the U(L)17 gene. A virus derived from HSV-1(U(L)17-stop) but containing a restored U(L)17 gene was also constructed and was designated HSV-1(U(L)17-restored). The latter virus formed plaques and cleaved genomic viral DNA in a manner indistinguishable from wild-type virus. Neither HSV-1(deltaU(L)17) nor HSV-1(U(L)17-stop) formed plaques or produced infectious progeny when propagated on noncomplementing Vero cells. Furthermore, genomic end-specific restriction fragments were not detected in DNA purified from noncomplementing cells infected with HSV-1(deltaU(L)17) or HSV-1(U(L)17-stop), whereas end-specific fragments were readily detected when the viruses were propagated on complementing cells. Electron micrographs of thin sections of cells infected with HSV-1(deltaU(L)17) or HSV-1(U(L)17-stop) illustrated that empty capsids accumulated in the nuclei of Vero cells, whereas DNA-containing capsids accumulated in the nuclei of complementing cells and enveloped virions were found in the cytoplasm and extracellular space. Additionally, protein profiles of capsids purified from cells infected with HSV-1(deltaU(L)17) compared to wild-type virus show no detectable differences. These data indicate that the U(L)17 gene is essential for virus replication and is required for cleavage and packaging of viral DNA. To characterize the U(L)17 gene product, an anti-U(L)17 rabbit polyclonal antiserum was produced. The antiserum reacted strongly with a major protein of apparent Mr 77,000 and weakly with a protein of apparent Mr 72,000 in wild-type infected cell lysates and in virions. Bands of similar sizes were also detected in electrophoretically separated tegument fractions of virions and light particles and yielded tryptic peptides of masses characteristic of the predicted U(L)17 protein. We therefore conclude that the U(L)17 gene products are associated with the virion tegument and note that they are the first tegument-associated proteins shown to be required for cleavage and packaging of viral DNA.

Production of soluble single-chain T-cell receptor fragments in Escherichia coli trxB mutants

Antibodies and T cell receptors (TCR) both belong to the immunoglobulin superfamily whose members are characterised by the possession of one or more immunoglobulin domains. The production of soluble single chain antibody fragments in Escherichia coli has, in recent years, become a routine laboratory procedure. In contrast, the production of T cell receptors in bacteria has remained problematic as the majority of the recombinant protein is insoluble. In this paper we show that single chain TCR produced in E. coli BL21 (DE3) and directed to the periplasm was also insoluble and that this was in part due to the failure of the cell protein processing machinery to cleave the pelB leader sequence. This problem was overcome by expressing the single chain TCR in the cytoplasm of E. coli which carry an inactive thioredoxin reductase gene. This strain allows the formation of disulphide bonds in the cell cytoplasm which we believe encourages the correct folding of the recombinant protein. We have constructed both a human and mouse single chain TCR in these bacteria and demonstrated using BIAcore technology that these molecules have folded in a conformation which allows their recognition by conformational specific ligands. In addition, we have used one of our soluble single chain TCR preparations to isolate a TCR specific Fab molecule from a phage antibody library.

Complications of hysterectomy

Hysterectomy is a popular operation that has a number of complications associated with it. The most common are hemorrhage, infection, and injuries to adjacent organs. Unintended major surgical procedures and second operations occur in approximately 4% of patients undergoing hysterectomy. Laparoscopic hysterectomy is a controversial new procedure that has both advocates and detractors. In skilled hands, the complication rate of laparoscopic hysterectomy does not exceed that of traditional hysterectomy methods. At the present time, there is a growing consensus that removal of the uterus only does not lead to an increase in psychosexual morbidity. It also appears that hysterectomy procedures have little, if any, effect on lower urinary tract function.

Natural antibodies that react with V-region peptide epitopes of DNA-binding antibodies are made by mice with systemic lupus erythematosus as disease develops

Cross-reactive idiotypes (CRI) have been detected on anti-DNA autoantibodies associated with lesions typical of systemic lupus erythematosus. In order to analyse the antigenic make up of idiotypes on anti-DNA monoclonal antibodies (mAb) V-88 (IgG1 kappa) and F-423 (IgG3 kappa), derived respectively from an adult (NZB x NZW)F1 and a fetal MRL/Mp-lpr/lpr mouse, a set of overlapping hexapeptides representing the VH and VL regions of mAb V-88 and F-423 were synthesized and reacted with a range of sera in pepscan enzyme-linked immunosorbent assays (ELISA) taken from normal and lupus mouse strains. Serum pools were collected both from normal BALB/c and lupus MRL/Mp-lpr/lpr and (NZB x NZW)F1 mice at 10, 20 and 30 weeks of age and analysed for the presence of spontaneously produced anti-V-region peptide IgM and IgG antibodies. IgM antibodies from both the lupus mice reacted with the same V-region epitopes, and although some epitopes mapped to similar locations in the two mAb, the maps for V-88 and F-423 were not identical. In MRL/Mp-lpr/lpr mice, as lupus disease progressed there was a switch from IgM antibodies to IgG anti-peptide antibodies whose specificity for the peptide antigens coincided with but was better defined than that of the IgM antibodies. The identified idiotopes were located in both complementary determining regions (CDR) and framework region (FR) regions, indicating that some contribute to CRI shared by other related antibodies, while others were unique to either mAb V-88 or F-423. In conclusion, we have dissected and identified a mosaic of antibody V-region idiotopes that contribute to the idiotype of an anti-DNA autoantibody and against which autoantibodies are made naturally in lupus disease.

A humanized antibody against human cytomegalovirus (CMV) gpUL75 (gH) for prophylaxis or treatment of CMV infections

A humanized monoclonal antibody that binds to the 86-kDa glycoprotein, gpUL75 (gH), of human cytomegalovirus (CMV) has been developed. The six complementarity determining regions of the heavy and light chains of the mouse antibody HCMV16 were transferred to human antibody framework sequences and combined with human antibody constant regions to produce a complete antibody. The reshaped antibody recognized cells infected with a variety of virus strains and neutralized clinical isolates of CMV as efficiently as laboratory strains in a conventional plaque reduction assay. This antibody provides a potential agent for the prevention or treatment of CMV infections in humans.

Early complications of laparoscopic hysterectomy

Since Reich first described laparoscopic hysterectomy (LH) in 1989, a number of series have appeared in the literature detailing complications of this procedure. This review included all series obtained through a MEDLINE search from April 1989 through October 1994. Also included were series from the Journal of Gynecologic Surgery, Gynaecological Endoscopy, and the Journal of the American Association of Gynecologic Laparoscopists. Rates of various complications were calculated and compared with existing standards for abdominal and vaginal hysterectomy. Hemorrhage and injury to adjacent organs were fairly similar between traditional hysterectomy methods and LH. Infectious morbidity, however, was decreased in LH. Caution should be used in interpreting these data, as these initial reports come predominantly from leading experts in the field of endoscopic surgery. Whether these rates can be duplicated in a community hospital is debatable.

Simultaneous detection of microorganisms in soil suspension based on PCR amplification of bacterial 16S rRNA fragments

The effect of buffer composition on simultaneous PCR amplification of 16S rRNA gene fragments of five bacterial species was examined using a number of different buffer systems. Tris-based PCR buffers at final concentrations of 10 mM proved unreliable. However, when the final concentration of Tris was increased to 75 mM, all five samples were routinely detected. The use of other buffers, 3-[(1,1-dimethyl-2-hydroxyethyl)amino]-2-hydroxypropanesulfonic acid (AMPSO) and 3-[cyclohexylamino]-2-hydroxy-1-propanesulfonic acid (CAPSO), resulted in PCR amplification of five products even at low final concentrations (10 mM). The presence of certain proteins in the amplification reaction could overcome an inhibitory effect seen when soil suspension was present in the reaction, as might occur when testing field samples for the presence of bacteria. Bovine serum albumin was found to be the most effective additive tested in overcoming inhibition.

Cloning of a cellulase gene from the rumen anaerobe Fibrobacter succinogenes SD35 and partial characterization of the gene product

A gene encoding an enzyme which degrades cellulose (end-1) was isolated from a library of Fibrobacter succinogenes SD35 DNA fragments and expressed in pUC18. The product of end-1 showed significant activity against carboxymethylcellulose but relatively minor activity against lichenan, xylan and avicel. The nucleotide sequence indicated a product of 388 amino acids with a molecular mass of 50.2 kDa. This was in agreement with the molecular size estimated by gel electrophoresis. No significant DNA sequence similarity was identified with any published endoglucanase.

Early complications of abdominal and vaginal hysterectomy

In 1982, the Collaborative Review of Sterilization (CREST) study was published, reviewing the complications accompanying and following both abdominal and vaginal hysterectomy. This review was undertaken to see how these rates have changed in the ensuing years. All large series of abdominal and vaginal hysterectomy complications published subsequent to the CREST study were reviewed. Additionally, other studies that focused on specific complications were reviewed. It is concluded that the following changes related to hysterectomy morbidity have occurred since the publication of the CREST study: 1) the use of blood transfusion has diminished due to concern regarding human immunodeficiency virus contamination; 2) the rate of urinary tract infection has decreased primarily due to routine use of prophylactic antibiotics; and 3) inadvertent injury to the bladder has been noted more frequently at a rate of 1 to 2 percent. A particularly important category of complication is "unintended major surgical procedures which accompany or follow hysterectomy." This has been shown to occur at a rate of approximately 4 percent on general gynecology services. Finally, risk factors that add to the morbidity of hysterectomy are discussed.

Expression of monovalent and bivalent antibody fragments in Escherichia coli

The technology of humanization of rodent antibodies has opened the way for a broad range of therapeutic antibodies with very low immunogenicity, which are, therefore, suitable for repeated dosing. Such intact antibodies have extended serum half-lives and biodistribution profiles very similar to human antibodies. For some applications, however, the ideal therapeutic should have reduced serum half-life and altered biodistribution patterns typical of antibody fragments, such as Fab or single chain Fv. Bispecific antibody fragments offer exciting additional therapeutic possibilities, but their successful manufacture and purification on a large scale require the development of new methods. Antibody fragments often assemble in Escherichia coli as monovalent fragments with reduced affinities. We describe the spontaneous assembly of bivalent antibody fragments in E. coli and methods of purification that yield either bivalent or monovalent molecules as required.

Cloning, expression and characterization of a single-chain antibody fragment to the herbicide paraquat

New cost effective methods for the detection and removal of pesticides from water samples are required to meet modern safety standards. The recent development of techniques to produce antibody fragments in bacteria has provided the opportunity to exploit antibodies as specialized chemicals for affinity detection/removal technologies. The variable heavy and light polypeptide chains of the anti-paraquat monoclonal antibody PQXB1/2 have been cloned into the single-chain antibody (ScAb) expression vector pBG1. The construct was expressed in Escherichia coli and 0.4 mg functional antibody produced from 1 dm3 of induced culture. Characterization of ScAb by antigen binding profile and competition ELISA showed it to have a sensitivity one order of magnitude below that of the parent monoclonal. ScAb was purified as a monomer or dimer and analysed by HPLC size exclusion chromatography. When immobilized on polystyrene beads the ScAb could remove 85% of a paraquat-bovine serum albumin conjugate from solution in a single step.

Separation and concentration of bacteria with immobilized antibody fragments

New methods to quantitatively remove bacteria from food and water samples are required to meet modern safety standards. The recent development of techniques to make Fab/Fv/scFv fragments in bacteria has provided the opportunity to exploit antibodies as specialized chemicals for affinity removal technologies. Single-chain fragments against Pseudomonas aeruginosa have been expressed in Escherichia coli, purified via a fused poly-histidine tail and immobilized upon polystyrene beads. The resulting immunoaffinity columns have been shown to effectively remove greater than 90% of an applied 10 million bacteria after a single passage through the column. Column material in the absence of single-chain retained less than 10% of the bacteria. Pseudomonas were also removed from milk, mixed bacterial cultures and when present at low cell densities.

Identification of framework residues required to restore antigen binding during reshaping of a monoclonal antibody against the glycoprotein gB of human cytomegalovirus

Introduction of the complementary determining regions (CDRs) from a murine antibody to a human monoclonal antibody is an important technique (humanization) in the development of human immunotherapeutics. We have humanized murine monoclonal antibody HCMV37 which binds to the gB envelope glycoprotein of human cytomegalovirus. Simple transfer of the murine HCMV37 CDRs into heavy- and light-chain framework regions (FRs) based on human NEW and REI, respectively, together with human IgGI and K constant regions, abolished antigen binding because of a suboptimal heavy chain. Replacement of human VH amino acids Leu70, Val71 and Arg94 with murine residues Thr70, Arg71 and Asn94 was insufficient to improve affinity. However, significant restoration of binding was obtained by substitution of human VH amino acids Thr28, Phe29, Ser30 with murine residues Ser28, Ile29, Thr30, in conjunction with the position 94 change. Residue 71, often regarded as critical for antigen binding, was not a major factor.

Specificity analysis of blood group Lewis-y (Le(y)) antibodies generatedagainst synthetic and natural Le(y) determinants

Le(y)-reactive monoclonal antibodies (mAbs) were generated in mice by immunization with synthetic Le(y) neoglycoproteins or with Le(y)-expressing cells. Serological analysis indicated that mAbs raised against synthetic Le(y) (i) reacted strongly with synthetic Le(y) but poorly with natural Le(y), (ii) cross-reacted with Le(x) or H-type 2 structures, and (iii) were IgG1, IgG2a, or IgG2b. mAbs raised against Le(y)-expressing cells (i) reacted with both synthetic Le(y) and natural Le(y), (ii) were of two types: cross-reactive with Le(x) or H-type 2 structures or specific for Le(y), and (iii) were IgM or IgG3. One of the mAbs raised against natural Le(y), mAb 3S193 (IgG3), showed high specificity for Le(y) in ELISA tests with synthetic Le(y) and Le(y) containing glycoproteins and glycolipids; it also reacted strongly in rosetting assays and cytotoxic tests with Le(y)-expressing cells. mAb 3S193 did not lyse O, A, AB, and B human erythrocytes in the presence of human complement. In flow cytometry, there was weak reactivity with granulocytes, a reactivity also observed with two previously described highly specific Le(y) mouse mAbs--BR55-2 (IgG3) and B3 (IgG1). A humanized version of mAb 3S193 has been constructed, and the specificity pattern and reactivity for Le(y) remain very similar to mouse mAb 3S193.

Sequences of heavy and light chain variable regions from four bovine immunoglobulins

Oligodeoxyribonucleotide primers based on the 5' ends of bovine IgG1/2 and lambda constant (C) region genes, together with primers encoding conserved amino acids at the N-terminus of mature variable (V) regions from other species, have been used in cDNA and polymerase chain reactions (PCRs) to amplify heavy and light chain V region cDNA from bovine heterohybridomas. The amino acid sequences of VH and V lambda from four bovine immunoglobulins of different specificities are presented.

Efficient generation of a reshaped human mAb specific for the alpha toxin of Clostridium perfringens

We have used the technique of antibody reshaping to produce a humanized antibody specific for the alpha toxin of Clostridium perfringens. The starting antibody was from a mouse hybridoma from which variable (V) region nucleotide sequences were determined. The complementarity-determining regions (CDRs) from these V regions were then inserted into human heavy and light chain V region genes with human constant region gene fragments subsequently added. The insertion of CDRs alone into human frameworks did not produce a functional reshaped antibody and modifications to the V region framework were required. With minor framework modifications, the affinity of the original murine mAb was restored and even exceeded. Where affinity was increased, an altered binding profile to overlapping peptides was observed. Computer modelling of the reshaped heavy chain V regions suggested that amino acids adjacent to CDRs can either contribute to, or distort, CDR loop conformation and must be adjusted to achieve high binding affinity.

Initial experience with the Boyle uterine elevator

Since 1990, our institution has used the Boyle uterine elevator in 57 abdominal hysterectomies. The device aids in retraction of the uterus and minimizes the use of self-retaining retractors and bowel packing. The uterine elevator also aids in dissection of the bladder and incision of the cardinal and uterosacral ligaments. The mean hospital stay has been reduced to 2.6 days. Postoperative complications are rare. We conclude that this device is a useful adjunct in the performance of abdominal hysterectomy.

Expression of foreign genes in mammalian cells using an antibody fusion system

An expression system is described whereby a gene product is expressed fused to an antibody Fab fragment to form an antibody-like molecule. The antigen binding function of the original antibody is retained and the foreign gene replaces the CH2 and CH3 regions of the heavy chain. The fusion protein is secreted as if it were an antibody, and can be purified using the antigen-binding function of the Fab-like part of the molecule. In principle, any open reading frame can be expressed and it is not necessary to develop an individual purification scheme, or any analytical reagents such as antibodies, for the expressed protein, as both these functions can be performed by the Fab part of the fusion protein. In practice, the nature of the nonantibody part of the fusion influences the efficiency of expression and secretion, and detailed guidance is given on trouble-shooting and maximizing expression.

Spontaneous assembly of bivalent single chain antibody fragments in Escherichia coli

The ability of immunoglobulin Fab and single chain (ScFv) fragments to penetrate effectively into tissue from the vascular system has made these molecules excellent candidates as drug delivery systems and imaging tools. This study investigates the use of single chain antibody fragment bacterial expression vectors as a possible strategy for the production of these molecules. We have modified the pSW1-VHD1.3-VKD1.3-TAG1 vector [Ward et al. (1989) Nature 341, 544-546] which originally, when expressed in E. coli, produced an Fab fragment. In an effort to improve the affinity of the parent vector product a novel single chain antibody construct which encodes a protein with anti-P. aeruginosa activity was generated using a 14 amino acid linker [Chaudhary et al. (1990) Proc. natn. Acad. Sci. U.S.A. 87, 1066-1070]. In addition to the heavy and light chain variable domain genes, our construct also contained the light chain kappa constant domain gene to aid purification of the fragments. To underline this difference from the conventional ScFv fragment we have described this protein as a ScAb. The ScAb generated had an antigen binding capacity similar to the parent anti-P. aeruginosa antibody but was superior to the recombinant anti-P. aeruginosa Fab fragment. On HPLC and non-denaturing gel electrophoresis analysis, the ScAb was found to exist in multimeric forms while the Fab fragment existed only as a single unit. Dimeric ScAb had a similar antigen binding profile to the parent antibody.

Cloning and expression in Escherichia coli of the cDNA encoding human cardiac troponin I

We have cloned and sequenced the human cardiac troponin I (cTnI)-encoding cDNA with the aim of expressing the cDNA in Escherichia coli. The cDNA was successfully expressed as a fusion product with beta-galactosidase and as an unfused protein. Both polypeptides were recognised by an anti-human cTnI antibody.

Humanized antibodies

Hybridoma technology enabled rodent monoclonal antibodies to be created against human pathogens and cells, but these had limited clinical utility. Protein engineering is now generating antibodies for treatment of infectious disease, autoimmune disease and cancer by 'humanizing' rodent antibodies. Humanized antibodies have improved pharmacokinetics, reduced immunogenicity and have been used to clinical advantage.

Humanized antibodies

Hybridoma technology enabled rodent monoclonal antibodies to be created against human pathogens and cells, but these had limited clinical utility. Protein engineering, reviewed her by Greg Winter and William Harris, is now generating antibodies for treatment of infectious disease, autoimmune disease and cancer by 'humanizing' rodent antibodies. Humanized antibodies have improved pharmacokinetics, reduced immunogenicity and have been used to clinical advantage.

Total knee arthroplasty without patellar resurfacing. Clinical outcomes and long-term follow-up evaluation

Total knee arthroplasty (TKA) without resurfacing of the patella by a single surgeon was reviewed retrospectively in 125 patients: 66 patients (79 knees) were included in the final study group, 32 patients were deceased, 13 were without current address and not able to be contacted, and 14 patients were unable to complete a questionnaire because of severe illness or language barrier. All patients had a diagnosis of osteoarthrosis. The decision to leave the patella unresurfaced was based on the presence of satisfactory patellar articular cartilage, absence of eburnated bone, congruent patellofemoral tracking, normal anatomic patellar shape, and no evidence of crystalline disease or an inflammatory synovitis. A lateral retinacular release was performed in 13 knees (16.5%) to facilitate congruent patellar tracking. The follow-up period averaged 7.5 years (range, 2.4-15.5 years). There were no component revisions and no reoperations. The mean Knee Society score improved from 23.2 to 89.9 postoperatively and the function score improved from 58.4 to 92.0 postoperatively. Mild anterior knee pain was reported in 19%. Satisfaction with the surgical result was expressed in 89.5% of patients; 4% were somewhat satisfied; 2.6% were somewhat dissatisfied; and 4% were neutral. Of the patients who had mixed bilateral TKA (one TKA with unresurfaced patella, the other resurfaced), 46% rated both as equal; 46% preferred the TKA with the resurfaced patella; and 7.7% preferred the unresurfaced patella. In patients meeting the selection criteria outlined above, TKA without resurfacing of the patella provided satisfactory long-term results and a high degree of patient satisfaction with an absence of mechanical complications and no reoperations at the average 7.5-year follow-up evaluation.(ABSTRACT TRUNCATED AT 250 WORDS)

Uterine dehiscence following laparoscopic myomectomy

BACKGROUND

Laparoscopic myomectomy is a new procedure that is growing in popularity. The natural history of pregnancy following laparoscopic myomectomy is unknown.

CASE

A 24-year-old white woman, gravida 0, with infertility and endometriosis, conceived after a laparoscopic procedure that included myomectomy. At 34 weeks' gestation, the patient experienced uterine dehiscence at the site of myomectomy. An emergency cesarean delivery was performed and the uterus was oversewn. Both mother and infant had satisfactory hospital courses.

CONCLUSION

Meticulous closure of the myometrial bed following myomectomy is difficult via the laparoscope, and this could interfere with the integrity of the scar. If further studies confirm this experience, then laparoscopic myomectomy may need to be limited to patients who do not desire further childbearing.

Methods for assessing condition-specific and generic functional status outcomes after total knee replacement

Many assume that, relative to generic measures, condition-specific health measures are both more sensitive to the condition's severity and more specific because they are less affected by other conditions. We analyzed the sensitivity and specificity of the generic SF-36, condition-specific scales based on the SF-36, and condition-specific measures based on the Knee Society's Clinical Rating System in a study of osteoarthritis patients following knee replacement. As hypothesized, knee-specific role function and pain measures were more specific than generic measures among patients with other comorbid conditions, and less so among patients with only knee problems. Physical function scales of both types were equally specific. Clinical indicators based on x-ray and range of motion were only weakly related to all measures of function.