Abstract 4361: The plasma proteome as a cardiovascular disease risk assessment tool in cancer survivors

Cardiovascular disease (CVD) is the most common non-cancer cause of death in cancer survivors and there is an unmet clinical need for easy, accurate, and safe CVD prognostic risk-stratification in adult cancer survivors. This study investigated whether a previously validated 27-plasma protein prognostic model for four-year cardiovascular (CV) events could have such a utility. We used the 27-plasma protein model to predict the four-year risk of a CV event (myocardial infarction, stroke, transient ischemic attack, heart failure hospitalization, death) in 906 participants with a prior history or active malignancy of any type of cancer and compared predictive results to follow-up CV outcome data. The participants were from the BASEL VIII or ARIC (visit 3) studies with a medically adjudicated prior diagnosis of cancer. BASEL VIII is an observational cohort study in patients with suspected coronary artery disease. ARIC is a multi-site cohort study funded by the NHLBI, NCI, and NPCR investigating risk factors for CV health. A subset analysis was conducted to assess model performance in participants with no prior history of CVD and those with stable CVD. The 27-plasma protein model accurately stratified participants into 4 distinct and non-overlapping (95% CI) risk bins. The median time to event for all cancer survivors who had an event in this study was 1.3 years. Observed 4-year event rates across the 4 risk bins (low, medium-low, medium-high, and high) were 11.0%, 17.3%, 31.2% and 60.2%, respectively, which were higher than stratified event rates from our previously published metacohort analyses (5.6%, 11.2%, 20.0% and 43.4%, respectively) in participants with elevated CVD risk factors (e.g., prior events, diabetes, kidney disease and suspected coronary artery disease). The plasma protein model accurately predicted 4-year CVD risk with a C-index of 0.71 (0.68, 0.74) and 4-year AUC of 0.74 (0.69, 0.79). Performance of the protein model was comparable between participants with no prior history of CVD (C-Index: 0.69; AUC: 0.71) and stable CVD (C-Index: 0.69; AUC: 0.72), demonstrating the model accurately predicts CV event risk in cancer survivors regardless of cardiovascular history. Cancer survivors in this cohort can be distinguished with 4-year CV event rates as high as 60.2%, underscoring the urgent need for an easy and accurate risk stratification tool for this population. Prognostic protein testing may provide a novel tool for CVD risk assessment in adult cancer survivors.

Citation Format: Emma V. Troth, Matthew Ayala, Jessica Chadwick, Erin Hales, Michael Hinterberg, Jessica N. Kuzma, Clare Paterson, Rachel Ostroff, Joan E. Walter, Christian Mueller, Josef Coresh. The plasma proteome as a cardiovascular disease risk assessment tool in cancer survivors. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4361.

Multiple trauma management in mountain environments - a scoping review : Evidence based guidelines of the International Commission for Mountain Emergency Medicine (ICAR MedCom). Intended for physicians and other advanced life support personnel

Background

Multiple trauma in mountain environments may be associated with increased morbidity and mortality compared to urban environments.

Objective

To provide evidence based guidance to assist rescuers in multiple trauma management in mountain environments.

Eligibility criteria

All articles published on or before September 30th 2019, in all languages, were included. Articles were searched with predefined search terms.

Sources of evidence

PubMed, Cochrane Database of Systematic Reviews and hand searching of relevant studies from the reference list of included articles.

Charting methods

Evidence was searched according to clinically relevant topics and PICO questions.

Results

Two-hundred forty-seven articles met the inclusion criteria. Recommendations were developed and graded according to the evidence-grading system of the American College of Chest Physicians. The manuscript was initially written and discussed by the coauthors. Then it was presented to ICAR MedCom in draft and again in final form for discussion and internal peer review. Finally, in a face-to-face discussion within ICAR MedCom consensus was reached on October 11th 2019, at the ICAR fall meeting in Zakopane, Poland.

Conclusions

Multiple trauma management in mountain environments can be demanding. Safety of the rescuers and the victim has priority. A crABCDE approach, with haemorrhage control first, is central, followed by basic first aid, splinting, immobilisation, analgesia, and insulation. Time for on-site medical treatment must be balanced against the need for rapid transfer to a trauma centre and should be as short as possible. Reduced on-scene times may be achieved with helicopter rescue. Advanced diagnostics (e.g. ultrasound) may be used and treatment continued during transport.

P634 Right atrial mechanics determined by speckle tracking strain as a more physiologic correlation in pulmonary hypertension

Introduction

Right atrial dilation has also been established as a marker of adverse outcomes in pulmonary hypertension (PH), while right atrial mechanics remain relatively understudied.

Purpose

Transthoracic echocardiography is a practical and widely used tool for risk stratification in PH. We hypothesized that right atrial (RA) strain components [RA reservoir function (ƐR), peak RA contraction (ƐCT) and RA conduit function (ƐCD)] correlates better with strong prognostic parameters as 3D right ventricle ejection fraction (3D RV EF), 6 minutes walking test, systolic pulmonary artery pressure (SPAP) and B-type natriuretic peptide (BNP).

Methods

19 patients with diagnostic PH, type 2 patients were excluded. RA strain was analyzed and determined a correlation with right ventricle function and pulmonary variables.

Results

Morphology correlation was poor with all the variables as SPAP, 6 Minutes walking test, BNP, only RA/LA index has a good correlation with BNP (R = 0.76, P = 0.0004). Right atrial mechanics with strain has good correlation: ƐR correlates with BNP (R= -0.70, P = 0.001) and with SPAP (R= -0.68, P = 0.001). ƐCD correlates with BNP (R=-0.75;P = 0,0002) and with SPAP (R=-0.68, P = 0.001). ƐCT has no correlation with E/e, 3D RV EF, SPAP, pulmonary vascular resistance (PVR), 6 minutes walking test neither BNP. Right atrial deformation sum correlations with 3D RV EF (R= -0.70, P = 0.001), with SPAP (R= -0.72, P = 0.0005), with PVR (R= -0.68, P = 0.001) and with BNP (R=-0.71, P = 0.001).

Conclusion

Right atrium morphological characteristics have poor correlation with variables that evaluate right ventricle function and with variables that predicts outcomes, as BNP, in this patients population. Only RA/LA index as morphology parameter has good correlation with BNP level. Meanwhile right atrial mechanics analyzed by strain has strong correlation with other variables of severity at PH. Right atrial deformation sum has better correlation than other strain parameters in our study.

Abstract P634 Figure. RIGHT ATRIAL DEFORMATION SUM CORRELATION

Enhancement of Peroxidase Stability Against Oxidative Self-Inactivation by Co-immobilization with a Redox-Active Protein in Mesoporous Silicon and Silica Microparticles

The study of the stability enhancement of a peroxidase immobilized onto mesoporous silicon/silica microparticles is presented. Peroxidases tend to get inactivated in the presence of hydrogen peroxide, their essential co-substrate, following an auto-inactivation mechanism. In order to minimize this inactivation, a second protein was co-immobilized to act as an electron acceptor and thus increase the stability against self-oxidation of peroxidase. Two heme proteins were immobilized into the microparticles: a fungal commercial peroxidase and cytochrome c from equine heart. Two types of biocatalysts were prepared: one with only covalently immobilized peroxidase (one-protein system) and another based on covalent co-immobilization of peroxidase and cytochrome c (two-protein system), both immobilized by using carbodiimide chemistry. The amount of immobilized protein was estimated spectrophotometrically, and the characterization of the biocatalyst support matrix was performed using Brunauer-Emmett-Teller (BET), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), and Fourier transform infrared (FTIR) analyses. Stability studies show that co-immobilization with the two-protein system enhances the oxidative stability of peroxidase almost four times with respect to the one-protein system. Thermal stability analysis shows that the immobilization of peroxidase in derivatized porous silicon microparticles does not protect the protein from thermal denaturation, whereas biogenic silica microparticles confer significant thermal stabilization.

Dasatinib compared to imatinib (IM) in patients (pts) with newly diagnosed chronic-phase chronic myelogenous leukemia in chronic phase (CML-CP): Twelve-month efficacy and safety from the phase III DASISION study

LBA6500

Background: Dasatinib is a highly potent BCR-ABL kinase inhibitor. Once daily dasatinib demonstrated high rates of durable complete cytogenetic response (CCyR) with 73% progression-free survival and 87% overall survival at 3 yrs in pts with CML-CP post IM failure. DASISION compares efficacy and safety of dasatinib and IM as initial treatment of CML-CP.

Methods: 519 pts with Ph(+) newly diagnosed CML-CP stratified by Hasford risk were randomized to dasatinib 100 mg QD (n = 259) or IM 400 mg QD (n = 260). The primary endpoint was 12-mo rate of confirmed CCyR (cCCyR; CCyR on 2 consecutive analyses; any # of metaphases). Other endpoints were rates of and times to CCyR and major molecular response (MMR).

Results: Pts characteristics were well balanced. Minimum follow-up was 12 mos; median treatment duration was 14 mos. 85% of dasatinib and 81% of IM pts remained on study. Median dose intensity was 99 mg/d for dasatinib and 400 mg/d for IM. cCCyR rate was superior for dasatinib vs IM (77% vs 66%, P = 0.0067). 12-mo CCyR and MMR rates ( Table ) were higher for dasatinib vs IM (CCyR: 83% vs 72%; MMR: 46% vs. 28%). MMR was obtained significantly faster with dasatinib (HR 2.0, P < 0.0001) as was CCyR (HR 1.5, P < 0.0001). Rates of transformation to AP/BC were 1.9% for dasatinib and 3.5% for IM. Grade 3/4 anemia (10% vs 7%) and neutropenia (21% vs 20%) were similar across arms; thrombocytopenia was more common for dasatinib (19% vs. 10%). Non-hematologic adverse drug reactions (all grades) in ≥10% of pts (dasatinib vs. IM) were fluid retention (19% vs 42%; including pleural effusion, all grade 1 or 2, 10% vs. 0%), nausea (8% vs. 20%), vomiting (5% vs. 10%), myalgia (6% vs.12%), muscle inflammation (4% vs. 17%) and rash (11% vs. 17%).

Conclusions: Dasatinib showed significantly higher and faster rates of CCyR and MMR vs IM. Given the predictive value of 12-mo CCyR and MMR and the favorable tolerability of dasatinib, dasatinib may improve long-term outcomes in pts with newly diagnosed CML-CP.

[Table: see text]

[Table: see text]

Toxicity of ultraviolet radiation exposure to the lens expressed by maximum tolerable dose

The maximum tolerable dose (MTD2.3:16) for avoidance of cataract on exposure to ultraviolet radiation (UVR)-300 nm in the rat was here estimated at 3.65 kJ/m2. Sprague-Dawley rats were unilaterally exposed to UVR in the 300 nm wavelength region. One week after the exposure, the intensity of forward light scattering was measured. Toxicity for continuous response events can be estimated with MTD. Current safety standards for avoidance of cataract after exposure to UVR are based on a binary response event. It has, however, recently been shown that UVR-induced cataract is a continuous dose-dependent event. MTD provides a statistically well-defined criterion of toxicity for continuous response events.

Biocatalytic chlorination of aromatic hydrocarbons by chloroperoxidase of Caldariomyces fumago

Chloroperoxidase from Caldariomyces fumago was able to chlorinate 17 of 20 aromatic hydrocarbons assayed in the presence of hydrogen peroxide and chloride ions. Reaction rates varied from 0.6 min(-1) for naphthalene to 758 min(-1) for 9-methylanthracene. Mono-, di- and tri-chlorinated compounds were obtained from the chloroperoxidase-mediated reaction on aromatic compounds. Dichloroacenaphthene, trichloroacenaphthene, 9,10-dichloroanthracene, chloropyrene, dichloropyrene, dichlorobiphenylene and trichlorobiphenylene were identified by mass spectral analyses as products from acenaphthene, anthracene, pyrene and biophenylene respectively. Polycyclic aromatic hydrocarbons with 5 and 6 aromatic rings were also substrates for the chloroperoxidase reaction. The importance of the microbial chlorination of aromatic pollutants and its potential environmental impact are discussed.

An action spectrum for UV-B radiation and the rat lens

PURPOSE

To determine an action spectrum for UV-B radiation and the rat lens and to show the effect of the atmosphere and the cornea on the action spectrum.

METHODS

One eye of young female rats was exposed to 5-nm bandwidths of UV-B radiation (290, 295, 300, 305, 310, and 315 nm). Light scattering of exposed and nonexposed lenses was measured 1 week after irradiation. A quadratic polynomial was fit to the dose-response curve for each wave band. The dose at each wave band that produced a level of light scattering greater than 95% of the nonexposed lenses was defined as the maximum acceptable dose (MAD). Transmittance of the rat cornea was measured with a fiberoptic spectrophotometer. The times to be exposed to the MAD in Stockholm (59.3 degrees N) and La Palma (28 degrees N) were compared.

RESULTS

Significant light scattering was detected after UV-B at 295, 300, 305, 310, and 315 nm. The lens was most sensitive to UV-B at 300 nm. Correcting for corneal transmittance showed that the rat lens is at least as sensitive to UV radiation at 295 nm as at 300 nm. The times to be exposed to the MAD at each wave band were greater in Stockholm than in La Palma, and in both locations the theoretical time to be exposed to the MAD was least at 305 nm.

CONCLUSIONS

After correcting for corneal transmittance, the biological sensitivity of the rat lens to UV-B is at least as great at 295 nm as at 300 nm. After correcting for transmittance by the atmosphere, UV-B at 305 nm is the most likely wave band to injure the rat lens in both Stockholm and La Palma.

Very high expression of an anti-carcinoembryonic antigen single chain Fv antibody fragment in the yeast Pichia pastoris

In this paper we report the development of a recombinant strain of the yeast Pichia pastoris, which secretes an anti-carcinoembryonic antigen single chain Fv (scFv) antibody fragment to the culture supernatant as a biologically active protein, at levels of 1.2 g l(-1). The yeast scFv was purified by IMAC, with a final yield of approximately 0.440 g of 93% pure scFv per liter of culture supernatant. The specific activity in ELISA of the yeast scFv was almost three times higher than that of a bacterial periplasmic counterpart. These results reaffirm that the yeast P. pastoris is a suitable host for high level production of scFv antibody fragments with potential in vivo diagnostic and therapeutic applications.

[Surgical treatment of anorectal fistulas. A 17-year experience at the Instituto Nacional de la Nutrición "Salvador Zubirán"]

INTRODUCTION

Surgical treatment for anorectal fistula may be difficult because of the risk of recurrence, prolonged healing or anal incontinence following the operation.

OBJECTIVE

To analyze the experience with the surgical management of ano-rectal fistula during a period of 17 years.

PATIENTS AND METHODS

The medical records of 105 patients with anorectal fistulas were reviewed retrospectively, with analysis of demographic and clinical data, operative treatment, and results.

RESULTS

There were 73% men and 27% women. Mean age was 45 years. 86% had an underlying chronic disease, most frequently diabetes mellitus (21%) and obesity (14%). No anatomic classification of the fistulous tract was done in 86% of cases, and inter-sphincteric tracts were the most frequent type in the classified cases. In 90% of cases, treatment was fistulectomy. Complications occurred in 13% of cases, mainly delayed healing (6.5%). Recurrent disease was documented in 11 cases (10%), and the majority were treated with a new fistulectomy. There were no cases with anal incontinence following the operation.

CONCLUSIONS

The necessity of performing the anatomic classification of ano-rectal fistula should be emphasized. Fistulectomy was the most frequent surgical procedure.

A bacterial single-chain Fv antibody fragment that inhibits binding of its parental anti-E-selectin monoclonal antibody to activated human endothelial cells

Using the polymerase chain reaction, we cloned, modified, and linked antibody variable (V) region coding genes from a mouse hybridoma, and produced a bacterial single-chain Fv (scFv) antibody fragment specific for E-Selectin. A vector of pBR322 origin, bearing the tryptophan promoter and the ompA bacterial signal peptide, was used to direct scFv expression to periplasm. The vector included a six-histidine coding sequence 5' to the scFv for the purification of the expressed protein using immobilized metal affinity chromatography (IMAC). We found that the VH-Linker-VL 32-33 kDa scFv remained insoluble after cellular fractionation, and transmission electron microscopy showed the new protein to be present in the periplasm as inclusion bodies. The scFv was solubilized using urea, purified using IMAC, and renatured to its active form. In a competitive enzyme-linked immunosorbent assay with activated human vein endothelial cells in the solid phase, the scFv competed for binding with the original monoclonal antibody.

High cytoplasmic expression in E. coli, purification, and in vitro refolding of a single chain Fv antibody fragment against the hepatitis B surface antigen

A single-chain Fv (scFv) antibody fragment against the hepatitis B surface antigen (HBsAg) was expressed in Escherichia coli in the form of two independent fusion proteins, with either 60 ('long') or 27 ('short') amino acid N-terminal encoding sequences related to human interleukin-2. Both fusion proteins were expressed insolubly and at high levels in the bacterial cytoplasm (approximately 30% of total bacterial protein in MM294 cells at a laboratory scale). When recombinant cells were cultured in 5-1 fermentors, expression and optical density increased 2- and 4-fold, respectively, compared to a previous periplasmic insoluble version of the same anti HBsAg scFv. After extraction and solubilization in urea, the cytoplasmic scFvs were purified using immobilized metal ion affinity chromatography, followed by DTT treatment, and refolding by dialysis against a basic pH buffer containing EDTA. The refolded scFvs recognized the recombinant HBsAg in ELISA. Results of an ELISA where antigen affinity chromatography repurified scFvs were used as standards, indicated that refolding efficiencies were high: 56.2% for the 'short' fusion scFv, and 50.6% for the 'long' fusion scFv. Corrected final yields of active scFv were 30.3 and 27.3 mg l-1, respectively, for the aforementioned fusion proteins, 5-6 times better than those reported for the periplasmic scFv variant.

[Retrorectal tumors]

OBJECTIVES

To analyze the clinical presentation, and diagnostic and therapeutic implications in patients with retro-rectal tumors.

METHODS

This paper reports two patients. Both patients had constipation and change in bowel habits, and the physical examination revealed the retro-rectal neoplasia. One of the patients had rectal intra-luminal invasion due to a schwannoma and underwent a transanal excision, with subsequent recurrence that required a combined abdomino perineal resection due to invasion of the tumor to the anorectal angle. The second patient had a teratoma and had a good outcome after a trans-sacral resection of the neoplasia.

CONCLUSIONS

Clinical suspicion is imperative to diagnose these rare tumors. Treatment of choice is complete resection of the tumor. Localization of the neoplasia, as evidenced by image studies will help to decide the best surgical approach.

The human breast cancer cell line IIB-BR-G has amplified c-myc and c-fos oncogenes in vitro and is spontaneously metastatic in vivo

IIB-BR-G is an undifferentiated, highly heterogeneous, hormone receptor negative human breast cancer cell line previously established in our laboratory from a patient's primary tumor. An in vitro growing cell line (IIB-BR-G) and a xenotransplanted tumor growing in nude mice (IIB-BR-G(NUDE)) were derived. To further characterize these systems, immunocytochemical analysis was performed for differentiation antigens (PEM 200 kDa, CEA, NCA 90 kDa), blood-group related antigens (Le(x), sTn), oncogenes and tumor suppressor gene products (Her-2/neu protein, p53), metastasis-related cathepsin D and CD63/5.01 Ag, and the chemokine monocyte chemotactic protein 1 (MCP-1). Expression of markers was heterogeneous in these different systems. Previously reported karyotypic analysis has shown extensive chromosomal alterations including double min. Searching for oncogene amplification, we detected augmented copy number of c-myc and c-fos, the last one with two rearranged fragments. No amplification was found for c-erbB-2 in the cell line or in IIB-BR-G(NUDE), although this oncogene was amplified in the patient's primary tumor DNA. The differences observed between the patient's tumor, the cell line and the IIB-BR-G(NUDE) tumors are probably due to clonal expansion of cell variants not present in the original tumor. Electron microscopy of IIB-BR-G growing cells revealed epithelial characteristics with abundant dense granules, presumably secretory, distributed all over the cytoplasm and great nuclear pleomorphism. In vitro, IIB-BR-G cells showed a significant number of invading cells by Matrigel assay. After nearly 40 sequential subcutaneous passages of the original xenograft through nude mice, 80% of recipients developed spontaneous metastases, primarily to the lung and lymph nodes. Since this experimental model allowed to analyze changes produced in cancer cells from the primary tumor during adaptation to in vitro and in vivo growth, our results provide novel insights on the behaviour of hormone independent metastatic breast cancer.

Acute copper intoxication after a Cu-Ca EDTA injection in rats

It has been claimed that Cu-Ca EDTA releases the Cu slowly into the blood when injected as a therapeutic agent for Cu deficiency, but when overdosing occurs, animals may die in a few hours after the injection, suggesting that Cu release is faster than expected. A total of 30 rats were divided into six equal groups and injected with Cu-Ca EDTA at 4, 6, 13, 33 or 64 mg/kg body weight, the sixth group acted as control. All rats were sacrificed 24 h later, with the exception of rats from groups 33 and 64 that died 7 and 2 h postinjection respectively. The rate of Cu transference to the liver increased linearly with the dose, from (X +/- S.E.) 14.88 +/- 3.14 in group 4, to 134.47 +/- 21.86 microg/h in group 64. Injected animals developed liver and kidney degeneration, hemorrhage and necrosis, which increased in severity with the Cu dose. Liver Cu accumulation was highest for group 13 (866.8 +/- 84.23 ppm DM), while in group 64 reached only 167.0 +/- 14.99 ppm. It is concluded that during acute Cu poisoning, the rate of transfer is responsible for the liver and kidney damage, rather than the total amount of transferred Cu to those organs, as it is the case in chronic Cu poisoning. The high rate of Cu transfer possibly surpasses the intrinsic mechanisms of Cu deposition and free Cu is left into the cell with the development of necrosis.

Antigen recognition characteristics and comparative performance in immunoaffinity purification of two monoclonal antibodies specific for the hepatitis B virus surface antigen

In this paper we describe the antigen recognition characteristics, variable region base and amino acid sequence, and performance as immunoaffinity chromatography ligands of two MAb specific to the alpha determinant of the HBsAg, derived from the same fusion. We show that the epitope recognized by CB-Hep.0 (IgM) is probably associated to an intrachain disulfide bond in the antigen. On the other hand, CB-Hep.1 (IgG2b) recognizes a heat-resistant non-conformation dependent antigenic determinant on HBsAg. PCR-cloning and sequencing of the variable regions of these two MAb indicated that both heavy chain variable regions were originated from the usage of the same germinal V and J genes. However, the outstanding differences in the size of the VH CDR3, and the absolute difference in the light chain sequences, suggest that the hybridomas were originated from different precursor B lymphocytes. With respect to their use as immunoaffinity chromatography ligands for the purification of a recombinant HBsAg, we found that the IgM immunogel exhibited increased performance with respect to amount of eluted antigen, and final recovery. This difference in overall performance could be attributed to a series of factors: the higher valence number of IgM, a dissimilar distribution of IgM and IgG in the activated gel particles, and differences in antigen recognition between both MAb. Our results suggest that IgM antibodies may be useful in immunopurification, particularly if the antigen is structurally complex and has a high density of repeating epitopes.

Vitamin D prophylaxis in children with a single dose of 150000 IU of vitamin D

OBJECTIVE

To determine the efficacy of a single oral dose of 150,000 IU of vitamin D2 at the beginning of autumn for preventing winter vitamin D deficiency in children in Ushuaia (55 degrees S).

DESIGN

The study was prospective.

SUBJECTS

79 children clinically healthy with 8.6 +/- 1.4 y of age (X +/- s.d.).

INTERVENTIONS

Fasting serum venous samples and 2 h urine samples were obtained immediately before and 6 w and 5 mon after the vitamin D dose. Parents informed consent was obtained previous to the study. In a subgroup of 30 children serum levels of calcium (sCa), phosphorus (sP), total alkaline phosphatase (TAP), 25 hydroxyvitamin D (25 OHD), parathyroid hormone (PTH) and the urine calcium/creatinine ratio in a 2 h urine sample (UCa/UCreat) were measured. In the whole group sCa and the ratio uCa/ucreat were measured.

RESULTS

After 150,000 IU of vitamin D2 administration, serum 25 OHD levels at the end of winter (17.0 +/- 9.4 ng/ml) were similar to those at the beginning of autumn (18.7 +/- 10.7 ng/ml), but significantly higher from those obtained in a previous study without vitamin D (9.8 +/- 3.8 ng/ml, P < 0.001). PTH levels were higher at the end of winter (P < 0.02), but this augmentation was lower than the increment observed without vitamin D. Plasma calcium levels and the urine calcium/creatinine ratio were lower at 5 months after vitamin D2 dose (P < 0.02 and P < 0.05 respectively). In the total group the serum calcium was lower after the fifth month (P < 0.05). The Uca/Ucreat ratio was lower at 6 w and 5 mon (P < 0.05 and P < 0.001).

CONCLUSION

A single dose of 150,000 IU of vitamin D maintained appropriate levels of 25 OHD without inducing hypercalcemia nor hypercalciuria, but a winter increment of PTH (smaller than in the group without vitamin D) was not inhibited.

Production, purification and characterization of an anti-(carcinoembryonic antigen) recombinant single-chain Fv antibody fragment

Specific targeting of radioactive agents to tumour cells has been the main objective of the in vivo use of monoclonal antibodies and their fragments. In particular, specific antibodies to carcinoembryonic antigen (CEA)-expressing tumours can be used either for diagnosis or therapy, if targeting could be improved. The expression of antibody fragments in bacteria allows the preparation of engineered molecules with antigen-binding properties and a better penetration into the tumour. A specific anti-CEA single-chain Fv fragment was produced in bacteria and purified. Its binding activity has been demonstrated in ELISA, immunocytochemistry, immunohistochemistry, fluorescence-activated cell sorting and the kinetic parameters determined by the plasmon surface resonance.

Epitope mapping, V-region DNA sequence, and neutralizing Fab fragments of two monoclonal antibodies against the HIV-1 V3 loop

BACKGROUND

Experimental evidence suggests that neutralizing antibodies could constitute an important factor in the control of AIDS progression and that the V3 loop of gp120 constitutes the main target for such purposes. We have previously developed two neutralizing murine monoclonal antibodies (Mabs) against the V3 region of the HIV-1 MN strain.

OBJECTIVES

To characterize those Mabs in terms of fine specificity and DNA sequence of their V regions and to study if Fab fragments retain their neutralizing potential in vitro.

STUDY DESIGN

A set of 12-mer alanine substituted peptides were employed for epitope mapping using two ELISA procedures: (1) indirect, with each peptide bound to polystyrene plates, and (2) competitive, with co-incubation of peptides and Mabs in solution. The V regions of both Mabs were PCR amplified from cDNA and their nucleotide sequences were determined. Finally, Fab fragments of Mab 10F10 were generated and their neutralizing capacity against the MN isolated was assessed.

RESULTS

We first restricted the minimal length of the epitopes recognized by 2C4 and 10F10 to the 12-mer peptide KRIHIGPGRAFY. The core of the epitopes recognized by Mabs 2C4 and 10F10 were IHIGP-R and IHIG-R, respectively. While substitution of proline in position 7 completely abolished the binding of 2C4, it only reduced that of 10F10 by 50%. Finally, Fab fragments of Mab 10F10 were still able to neutralize the HIV-1 MN strain in vitro.

CONCLUSION

This subtle distinction in the fine mapping of the epitope recognized by Mabs 2C4 and 10F10 should correspond to three amino acid differences that we found in the heavy chain V-regions. The Fab fragments of Mab 10F10 retained the neutralizing capacity. This indicates that HIV neutralization by anti V3 Mabs is an Fc independent process.

Purification and application of a single-chain Fv antibody fragment specific to hepatitis B virus surface antigen

Immobilized metal affinity chromatography (IMAC) has been recently applied to the purification of of recombinant proteins bearing multi-histidine domains at their N or C terminus. We have now used this procedure for the single-step purification of an anti-Hepatitis B virus surface antigen (HBsAg) single-chain Fv (scFv) antibody fragment. Adjusting the metal ion (Cu+2 or Ni+2) and elution conditions (pH or imidazole), we efficiently separated active scFv forms from inactive molecules. Achieved purity was 93%, with a 20% yield with respect to the scFv content in the initial material. The pure scFv was coupled to CNBr-activated Sepharose 4B and compared the original monoclonal antibody (MAb) CB-Hep.1 in the immunoaffinity purification of a vaccine recombinant HBsAg (r-HBsAg). Results indicate that eluted antigen per mg of coupled ligand was similar for the scFv and the MAb when pure r-HBsAg was used as starting material. Preliminary results with unpurified starting material are also encouraging.

A point mutation in a murine immunoglobulin V-region strongly influences the antibody yield in Escherichia coli

Recombinant DNA technology has made it possible to produce specific Fab and scFv antibody (Ab) fragments in prokaryotic host cells. Using vectors designed for periplasmic expression of encoded Ab fragments, we have been studying how the sequence and genetic localization of the light chain (L-chain) variable region gene of a mouse Ab (CB-Nm.1) determined the level of Ab production. The variable region was shown to belong to the V kappa V family and contained a previously unreported Ile72. Nine different Ab constructions were tested in monocistronic (scFv) or dicistronic (Fab) operons for their ability to affect the synthesis level of the L-chain. When the gene coding for the L-chain was located downstream from the Fd fragment gene, the substitution of codons encoding Ile by a codon encoding Thr was found to be crucial for any expression of the L-chain fragment. This was, however, not accompanied by an increase in L-chain-specific mRNA, neither was there any change in the size of the mRNA. The fact that the unmutated L-chain protein was produced from cells transformed with certain other constructions indicated that the protein as such was not incompatible with the prokaryotic environment. Together, this suggested that the translation process was involved in the restricted production of the L-chain. Thus, surprisingly small substitutions significantly affected the expression level, a fact that will have important implications on the library size expressed in prokaryotic hosts, including phage-displayed Ab libraries.

Variable region sequence modulates periplasmic export of a single-chain Fv antibody fragment in Escherichia coli

Using PCR, we have cloned antibody heavy and light chain variable region (VH and VL) coding sequences specific for a recombinant hepatitis B virus surface antigen (HBsAg) and assembled these for expression as single-chain Fv (scFv) fragments in Escherichia coli periplasm using the ompA signal peptide. The vectors also encoded N- or C-terminal His6 extensions to allow for the purification of the expressed proteins using immobilized metal affinity chromatography (IMAC). We found that the VH-linker-VL configuration of the scFv was not exported to the periplasm but remained associated with cellular insoluble material, from which it could be extracted, renatured to its active form by gentle dialysis and purified using IMAC. The molecular size of the scFv suggests that the ompA signal peptide was not processed. Based on previous reports, we hypothesized that the arginine in framework 1 (FR1) of the VH might interfere with translocation to the periplasm by means of the signal peptide. Because no arginines are present in FR1 of VL, we reversed the order of the V-regions in the scFv and observed efficient export of the active scFv to the periplasm. Furthermore, when the arginine in FR1 of VH was mutated to glycine in the original VH-linker-VL construct, active scFv was also exported to the periplasm. Thus, exposed positive charges near the signal peptide may account for at least some of the often-encountered difficulties in bacterial scFv expression.

Intra- and extracellular expression of an scFv antibody fragment in E. coli: effect of bacterial strains and pathway engineering using GroES/L chaperonins

We have studied the influence of bacterial host on the secretion of single-chain Fv antibody fragment (scFv), the production of this antibody fragment as intracellular fusion protein, and the effect of chaperonin coexpression on intracellular antibody expression. Seven bacterial strains were transformed with a vector carrying the genes encoding the variable regions of an anti-CEA scFv antibody and the ompA leader sequence (ptrp/ompA/scFvCEA). Expression and secretion of this antibody fragment were highest in the W3110 strain, as determined by Western blot analysis and enzyme immunoassay, where the scFv fragment amounted to approximately 30% of the total periplasmic protein. Except for BMH71-18, the other strains were unsuitable for antibody fragment expression, suggesting screening of bacterial strains as an important parameter. For intracellular expression, the scFv was expressed as a fusion protein with a 26-amino acid N-terminal fragment of human interleukin-2 (IL-2), using the pIL-2f/scFvCEA vector. The fusion protein was expressed at 30% of total biomass and retained antigen binding after in vitro refolding. Co-expression of chaperonin-encoding plasmid pGroES/L with pIL-2f/scFv increased the intracellular production of the fusion protein twofold, with a similar increase in the final amount of active scFv antibody fragment that could be obtained after in vitro refolding. The chaperonins had no effect on secretion of scFv antibody fragments, using the ptrp/ompA/scFvCEA.

Chaperonin assisted phage display of antibody fragments on filamentous bacteriophages

We have used the GroE chaperonins to assist in the packing of a new phage display vector, pEXmide3. Titers of the packed phagemid increased almost 200-fold from approximately 4 x 10(11) cfu/ml, without coexpression of the GroE proteins, to approximately 7 x 10(13) cfu/ml with their coexpression. Equal titers of non-assisted and assisted phagestocks exhibited the same antigen specificity and ELISA reactivity, indicating the same frequency of displayed Fab-fragments. While the diversity of antibody libraries depends on the bacterial transformation efficiency, the copy number of each antibody is determined by subsequent amplification of the phage, thus chaperonin assisted phagemid packing in bacteriophage M13 can be used as a general and simple tool to increase the amplification level of expressed Fab fragments. pEXmide3 was developed for display of Fab and single chain Fv-fragments (scFv), using restriction enzymes that do not cut, or cut with low frequencies, in genes encoding immunoglobulin variable domains. The vector allows cloning of genes for the variable domains linking these to predetermined human constant domains or cloning of the entire light and heavy Fab chains. A modification of the pelB leader sequence, with a glutamine to alanine substitution at residue 18, was used for export of the light chain.

Bacterial single-chain antibody fragments, specific for carcinoembryonic antigen

We have produced single-chain antibody (scFv) fragments in bacteria specific for carcinoembryonic antigen (CEA). Polymerase chain reaction (PCR) was used for the cloning and modification of the heavy and light variable regions (VH and VL) of the mouse monoclonal antibody (MAb) CB-CEA.1. A 14-amino acid linker was used in the synthesis of the scFv gene. The VH and VL regions were amplified from cDNA by PCR using 5' end FR1 and 3' end constant region primers, and then sequenced. VH was then amplified by PCR using an exact 5' end FR1 primer, and a phosphorylated (PP) 3' end primer for J2 that also encoded the first 7 amino acids of the linker. VL was amplified with a PP 5' end primer for FR1, also encoding the remaining 7 amino acids of the linker, and a 3' end primer for J5, plus a stop codon and a BglII restriction site. The fragments were ligated and reamplified with the PP VH 5' and VL 3' end primers. The VH-linker-VL structure was blunt-cloned into expression vectors bearing the tryptophan promoter and pelB or ompA signal peptide sequences. Culture supernatant, bacteria pellet and periplasm preparations were assayed in Western blot and a protein of about 27 kDa was identified with rabbit antibodies specific for the Fab of CB-CEA.1. Bacterial supernatant and periplasm preparations also inhibited the recognition of CEA by HRP-labeled CB-CEA.1 in enzyme-linked immunosorbent assay (ELISA). Periplasm preparations were purified by affinity chromatography with specific anti-idiotypic MAbs. The Western blot of the eluates identified a protein of approximately 27 kDa that blocked the recognition of CEA by HRP-labeled CB-CEA.1 in ELISA. The VH-linker-VL structure was cloned into a vector bearing the lacZ promoter and the pelB signal peptide. The recombinant bacterial clones also expressed about 27 kDa scFv, specific for CEA.

Primer design for the cloning of immunoglobulin heavy-chain leader-variable regions from mouse hybridoma cells using the PCR

To facilitate the rapid cloning and sequencing of rearranged murine heavy-chain variable regions, we have designed a set of universal primers using conserved sequences of leader (signal peptide), framework one and constant regions of the immunoglobulin heavy-chain genes. RNA was extracted from the mouse hybridoma cells secreting monoclonal antibodies: IOR-T3 (anti-CD3), C6 (anti-P1 of N. meningitidis B385), IOR-T1 (anti-CD6), CB-CEA.1 (anti-carcinoembryonic antigen), CB-Fib.1 (anti-human fibrin) and CB-Hep.2 (anti-hepatitis B surface antigen). First-strand cDNA was synthesized and amplified using PCR. The primers successfully amplified correct size fragments from cDNA prepared from all hybridomas. These methods will facilitate the cloning and sequencing of mouse immunoglobulin variable regions.

Specific amplification of rearranged immunoglobulin variable region genes from mouse hybridoma cells

In this article we show how the polymerase chain reaction (PCR) and primers designed for conserved sequences of leader (L), framework one (FR1) and constant (CONST) regions of immunoglobulin light and heavy chain genes can be used for the cloning and sequencing of rearranged antibody variable regions from mouse hybridoma cells. RNA was extracted from the mouse hybridoma cells secreting MAbs: IOR-T3a (anti-CD3), C6 (anti-P1 of N. meningitidis B385), IOR-T1 (anti-CD6), CB-CEA.1 (anti-carcinoembryonic antigen), and CB-Fib.1 (anti-human fibrin). First strand cDNA was synthesized and amplified using PCR. The newly designed primers are superior to others reported recently in the literature. Isolated PCR DNA fragments of C6 and IOR-T3a were sequenced after asymmetric amplification, or M13 cloning. The FR1/CONST primer combinations selectively amplified mouse lights chain of groups kappa II, V, and VI, and heavy chains of groups IIa and IIc. The L/CONST primers for light chains amplified light chains from all four hybridomas. These methods greatly facilitate structural and functional studies of antibodies by reducing the efforts required to clone and sequence their variable regions.

Relation of gastroesophageal sphincter pressure and esophageal contractile waves to age in man

Gastroesophageal sphincter pressure (GESP) and contractile waves of the esophagus were measured in 113 normal subjects ranging in age between 2 months and 74 years. The amplitude and duration of the peristaltic waves of the thoracic esophagus were similar in both children and adults. Resting GESP pressures were dependent upon age. In children under one year, high pressures were recorded. The high pressures gradually diminished until between 15 and 24 years, whereafter they remained at similar values up to 65 years. After this age, a further decline in pressure was observed. The importance of these findings are discussed.

Long-term clinical, radiological and manometric follow-up of patients with achalasia of the esophagus treated with esophagomyotomy

Twenty adult patients with achalasia of the esophagus were treated with an anterior esophagomyotomy and fundic patch. A significant decrease in resting gastroesophageal sphincter pressure was obtained immediately after surgery (p less than 0.001). One case was lost and the rest were followed up for 34 months. Patients had no esophageal symptoms and resting gastroesophageal sphincter pressure remained in low values. Surgical procedure is an adequate and definitive treatment for this disease.