Impregnation of Curcumin into a Biodegradable (Poly-lactic-co-glycolic acid, PLGA) Support, to Transfer Its Well Known In Vitro Effect to an In Vivo Prostate Cancer Model

Prostate cancer (PCa) is one of the most common cancers in older men and is associated with high mortality. Despite advances in screening for early detection of PCa, a large proportion of patients continue to be diagnosed with metastatic disease, with ~20% of men showing a high tumor grade and stage. Medicinal plant extracts have a great potential to prevent/treat PCa, as well as to reduce its incidence/prevalence and improve survival rates. One of the most promising extracts is curcumin, which is a major, nontoxic, bioactive compound of Curcuma longa. Curcumin has strong antitumor activity in vitro. However, its potential beneficial in vivo affects are limited by its low intestinal absorption and rapid metabolism. In this study, curcumin was impregnated into a biodegradable poly(lactic-co-glycolic) acid (PLGA) support and characterized by FTIR and DSC, and its release by UV spectrophotometry. PLGA-curcumin was tested in different subcutaneous PCa xenograft models (PC3, 22rv1, and DU145 PCa cell-lines), and its effects evaluated by tumor progression an immuno-histochemical analysis (Trichromic, Ki67 and TUNEL stainings), were compared with those of a commercial curcumin preparation. Our results indicate that curcumin-impregnated PLGA is significantly more active (~2-fold increase) with respect to oral curcumin, which supports its use for subcutaneous administration.

Effectiveness of an intervention in multicomponent exercise in primary care to improve frailty parameters in patients over 70 years of age (MEFAP-project), a randomised clinical trial: rationale and study design

Background

Physical activity may reverse frailty in the elderly, but we encounter barriers to the implementation of exercise programs in this population. Our main aim is to evaluate the effect of a multicomponent physical activity program, versus regular medical practice, on reverting pre-frailty status among the elderly, 12 months post-intervention.

Methods

Randomized parallel group multicenter clinical trial located in primary care setting, among non-dependent and pre-frail patients > 70 years old, including 190 patients (95 intervention, 95 control group). Intervention: Multicomponent physical activity program (MEFAP, for its acronym in Spanish) with twelve 1.5 h-weekly sessions comprised of: 1. Informative session; 2. Exercises for improving aerobic resistance, muscle strength, propioception-balance and flexibility; and 3. Handing out of at-home exercise chart (twice/week). Main variable: pre-frailty according to the Fried phenotype. Secondary variables: sociodemographic, clinical and functional variables; exercise program adherence, patient satisfaction with the program and quality of life. We will perform an intention-to-treat analysis by comparing the retrogression from pre-frailty (1 or 2 Fried criteria) to robust status (0 Fried criteria) by the end of the intervention, 6 months and 12 months post-intervention. The accumulated incidence in each group will be calculated, as well as the relative risk (RR) and the number needed to treat (NNT) with their corresponding 95% confidence intervals. Protocol was approved by the Ethics Committee Hospital la Paz.

Discussion

Within the context of regular clinical practice, our results will provide evidence regarding the effects of exercise interventions on frailty among pre-frail older adults, a key population given their significant potential for functional, physical, and mental health improvement.

Trial registration

NCT03568084. Registered 26 June 2018. Date of enrollment of the first participant to the trial: July 2nd 2018.

MI130004, a Novel Antibody-Drug Conjugate Combining Trastuzumab with a Molecule of Marine Origin, Shows Outstanding In Vivo Activity against HER2-Expressing Tumors

In the search for novel payloads to design new antibody-drug conjugates (ADC), marine compounds represent an interesting opportunity given their unique chemical features. PM050489 is a marine compound that binds β-tubulin at a new site and disrupts the microtubule network, hence leading to mitotic aberrations and cell death. PM050489 has been conjugated to trastuzumab via Cys residues through a noncleavable linker, and the resulting ADC, named MI130004, has been studied. Analysis of MI130004 delivered data consistent with the presence of two molecules of PM050489 per antibody molecule, likely bound to both sides of the intermolecular disulfide bond connecting the antibody light and heavy chains. The antitumor activity of MI130004 was analyzed in vitro and in vivo in different cell lines of diverse tumor origin (breast, ovary, and gastric cancer) expressing different levels of HER2. MI130004 showed very high in vitro potency and good selectivity for tumor cells that overexpressed HER2. At the cellular level, MI130004 impaired tubulin polymerization, causing disorganization and disintegration of the microtubule network, which ultimately led to mitotic failure, mirroring the effect of its payload. Treatment with MI130004 in mice carrying histologically diverse tumors expressing HER2 induced a long-lasting antitumor effect with statistically significant inhibition of tumor growth coupled with increases in median survival time compared with vehicle or trastuzumab. These results strongly suggest that MI130004 is endowed with remarkable anticancer activity and confirm the extraordinary potential of marine compounds for the design of new ADCs. Mol Cancer Ther; 17(4); 786-94. ©2018 AACR.

Sodium Tetramethoxyborate: An Efficient Catalyst for Michael Additions of Stabilized Carbon Nucleophiles

Sodium tetramethoxyborate, easily prepared by reaction of inexpensive sodium borohydride with methanol, possesses a suitable combination of a Lewis base and a Lewis acid to catalyze Michael reactions at room temperature under practically neutral conditions. This reaction provides good to excellent yields of Michael addition products from a broad scope of Michael donor and Michael acceptor reagents.

Adsorption Behavior of Bovine Serum Albumin on Lowly Activated Anionic Exchangers Suggests a New Strategy for Solid-Phase Proteomics

Diluted solutions of bovine serum albumin (BSA) (e.g., 0.1 mg /mL) do not form detectable protein large aggregates. Using gel-filtration experiments, we determined that a diluted solution of BSA is 97% monomeric BSA and 3% dimeric. The adsorption of this diluted BSA on highly activated anionic exchangers (e,g., having 40 micromol/wet g) keeps this mainly monomeric form. When supports activated with 2 micromol/wet g are used, only dimers become adsorbed to the support, accounting for 100% of the offered BSA. When the diluted BSA solution is offered to very mildly activated anionic exchangers (even only 0.125 micromol/wet g), an unexpected adsorption of most of the BSA on the support was also observed. These very slightly activated supports are only able to adsorb very large proteins or very large protein-protein complexes, larger than BSA dimers. In fact, a rapid cross-linking of the adsorbed BSA with dextran-aldehyde reveals the formation of very large BSA-BSA complexes with molecular mass higher than 500 000 Da, complexes that may be observed for soluble BSA with very high concentrations but are not detectable at 0.1 mg/mL. Moreover, the size of the aggregates strongly depends on the concentration of the ionized groups on the support: the less activated the supports are, the higher the sizes of the complexes. It seems that the interaction of the BSA molecules on the margins of the BSA aggregate with the groups on the support may stabilize the whole protein aggregate, although some components are not interacting with the support. Aggregates could account for more than 40% of the BSA in the solution after 50 h of incubation. However, only these large BSA aggregates were adsorbed in the support.

Menin molecular interactions: insights into normal functions and tumorigenesis

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disease predisposed by heterozygous germline mutations in the MEN1 tumor suppressor gene. Biallelic loss of MEN1 resulting from small mutation and/or loss of heterozygosity occurs in a large tissue spectrum of MEN1 tumors or non-hereditary tumors. Mouse models of MEN1 underexpression or overexpression have also supported the tumor-suppressor effect of the MEN1 gene. Menin, the 610-amino-acid protein encoded by MEN1, is expressed ubiquitously and found predominantly in the nucleus. Sequence analyses do not reveal motifs of known function other than two nuclear localization sequences. Menin has been found to partner in vitro with a variety of proteins that comprise transcription factors, DNA processing factors, DNA repair proteins, and cytoskeletal proteins. The diverse functions of menin interactors suggest roles for menin in multiple biological pathways. Inactivation of menin switches its JunD partner from a downstream action of growth suppression to growth promotion. This is a plausible mechanism for menin tumorigenesis.

Transient expression in tobacco leaves of an aglycosylated recombinant antibody against the epidermal growth factor receptor

When generating stably transformed transgenic plants, transient gene expression experiments are especially useful to rapidly confirm that the foreign molecule of interest is correctly assembled and retains its biological activity. TheraCIM(R) (CIMAB S.A., Havana) is a recombinant humanized antibody against the Epidermal Growth Factor receptor (EGF-R), now in clinical trials for cancer therapy in Cuba and other countries. An aglycosylated version (Asn 297 was mutated for Gln 297) of this antibody was transiently expressed in tobacco leaves after vacuum-mediated infiltration of recombinant Agrobacterium tumefaciens that carried a binary plasmid bearing the antibody heavy and light chain genes and plant regulation signals. Protein extracts from "agroinfiltrated" leaves were tested by ELISA and Western blot, showing that the fully assembled antibody was accumulated in plant tissues. The absence of plant specific glycans did not interfere in the assembling or in the activity of the plantibody, as demonstrated in this work. Indirect immunofluorescence demonstrated that the aglycosylated antibody expressed in plants recognizes the EGF-R expressed on the surface of A431 human tumor culture cells.

Topoisomerase I-mediated DNA cleavage as a guide to the development of antitumor agents derived from the marine alkaloid lamellarin D: triester derivatives incorporating amino acid residues

The marine alkaloid lamellarin D (LAM-D) has been recently characterized as a potent poison of human topoisomerase I endowed with remarkable cytotoxic activities against tumor cells. We report here the first structure-activity relationship study in the LAM-D series. Two groups of triester compounds incorporating various substituents on the three phenolic OH at positions 8, 14 and 20 of 6H-[1]benzopyrano[4',3':4,5]pyrrolo[2,1-a]isoquinolin-6-one pentacyclic planar chromophore typical of the parent alkaloid were tested as topoisomerase I inhibitors. The non-amino compounds in group A showed no activity against topoisomerase I and were essentially non cytotoxic. In sharp contrast, compounds in group B incorporating amino acid residues strongly promoted DNA cleavage by human topoisomerase I. LAM-D derivatives tri-substituted with leucine, valine, proline, phenylalanine or alanine residues, or a related amino side chain, stabilize topoisomerase I-DNA complexes. The DNA cleavage sites detected at T downward arrow G or C downward arrow G dinucleotides with these molecules were identical to that of LAM-D but slightly different from those seen with camptothecin which stimulates topoisomerase I-mediated cleavage at T downward arrow G only. In the DNA relaxation and cleavage assays, the corresponding Boc-protected compounds and the analogues of the non-planar LAM-501 derivative lacking the 5-6 double bond in the quinoline B-ring showed no effect on topoisomerase I and were considerably less cytotoxic than the corresponding cationic compounds in the LAM-D series. The presence of positive charges on the molecules enhances DNA interaction but melting temperature studies indicate that DNA binding is not correlated with topoisomerase I inhibition or cytotoxicity. Cell growth inhibition by the 41 lamellarin derivatives was evaluated with a panel of tumor cells lines. With prostate (DU-145 and LN-CaP), ovarian (IGROV and IGROV-ET resistant to ecteinascidin-743) and colon (LoVo and LoVo-Dox cells resistant to doxorubicin) cancer cells (but not with HT29 colon carcinoma cells), the most cytotoxic compounds correspond to the most potent topoisomerase I poisons. The observed correlation between cytotoxicity and topoisomerase I inhibition strongly suggests that topoisomerase I-mediated DNA cleavage assays can be used as a guide to the development of superior analogues in this series. LAM-D is the lead compound of a new promising family of antitumor agents targeting topoisomerase I and the amino acid derivatives appear to be excellent candidates for a preclinical development.

Humanization of predicted T-cell epitopes reduces the immunogenicity of chimeric antibodies: new evidence supporting a simple method

Genetic engineering has provided several approaches to reduce immunogenicity of murine antibodies. We described previously a new method based on the humanization of the linear epitopes presented to T cells. In brief, potential immunogenic epitopes in the variable region were identified and subjected to point mutations to make them human and/or to modify amphipatic motifs. The resulting recombinant antibody retained its antigen binding affinity and was less immunogenic in monkeys than their murine or chimeric predecessors are. The present study provides two new examples of this T-cell epitope humanization approach: ior-t1A murine monoclonal antibody (mMAb), which recognizes the human-CD6 molecule, and ior-C5 mMAb, which recognizes a novel glycoprotein expressed on the surface of malignant colorectal cells. Seven amino acids were substituted in ior-C5 and eleven residues in ior-t1A, by the corresponding residues from the highest homologous human sequences. Surprisingly, the homology between re-shaped chimeric antibody variable region frameworks and human sequences was 80-90%. Experiments in monkeys showed that T1AhT and C5hT "detopes" antibodies were less immunogenic than their chimeric analogues while they retained 30-50% of antigen binding affinities. The proposed method might be of general applicability to reduce immunogenicity of chimeric antibodies with therapeutic potential.

Biotransformations catalyzed by multimeric enzymes: stabilization of tetrameric ampicillin acylase permits the optimization of ampicillin synthesis under dissociation conditions

The importance of the stabilization of the quaternary structure of multimeric enzymes has been illustrated using a model reaction with great industrial relevance: the enzymatic synthesis of ampicillin from 6-amino penicillanic acid (6APA) and phenylglycine methyl ester (PGM) catalyzed by the tetrameric enzyme alpha-amino acid ester hydrolase from Acetobacter turbidans. The stabilization of the multimeric structure of the enzyme was achieved by multi-subunit immobilization of the enzyme followed by its further solid-phase chemical intersubunit cross-linking with polyfunctional macromolecules (dextran-aldehyde). This stabilized derivative has permitted the study of the reaction under conditions where nonstabilized enzyme molecules tended to dissociate (e.g., absence of phosphate ions). Synthetic yields improved from around 65%, under conditions where the nonstabilized derivative was stable, to around 85% in conditions where only the stabilized derivative could be utilized (40% methanol and absence of phosphate ions). When using high concentrations of PGM, a significant worsening of the reaction performance was detected with a significant decrease in the yields (below 55%, using 50 mM 6APA and PGM). This problem has been sorted out by using a fed-batch reaction system. By addition of PGM continuously to the reaction mixture (to maintain the concentration between 0.5 and 3 mM), 95% of 6-APA could be transformed to antibiotic (47.5 mM) by only using a 20% excess of acylating ester.

Multifunctional epoxy supports: a new tool to improve the covalent immobilization of proteins. The promotion of physical adsorptions of proteins on the supports before their covalent linkage

Multifunctional supports containing epoxy groups are here proposed as a second generation of activated supports for covalent immobilization of enzymes following the epoxy chemistry on any type of support (hydrophobic or hydrophilic ones) under very mild experimental conditions (e.g., low ionic strength, neutral pH values, and low temperatures). These multifunctional supports have been easily prepared by modifying a small fraction (10-20%) of the epoxy groups contained in commercial epoxy supports. In this way, additional groups that were able to physically adsorb proteins (e.g., cationic or anionic groups, metal chelate, phenyl boronate) are generated on the support surface. The covalent immobilization of proteins on these supports proceeds via their initial physical adsorption on the supports (via different structural features). Then, "intramolecular" covalent linkages between some nucleophilic groups of the adsorbed enzyme (e.g., amino, thiol, or hydroxy groups) and the dense layer of nearby epoxy groups on the support are established. This two-step covalent immobilization dramatically improves the very low reactivity of epoxy groups toward nonadsorbed proteins. In this way, all other relevant practical advantages of epoxy groups for protein immobilization (their high stability and their ability to form very strong linkages with several nucleophilic enzyme residues with minimal chemical modification) can be an object of universal exploitation. The use of these new multifunctional supports exhibits important advantages regarding immobilization of enzymes previously adsorbed on hydrophobic homofunctional epoxy supports: (i) hydrophilic supports can also be used for immobilization of industrial enzymes; (ii) immobilization can also be carried out at low ionic strength; (iii) every protein contained in crude extracts from Escherichia coli and Acetobacter turbidans can be immobilized by sequentially using a set of different supports; (iv) in most cases, each enzyme has been immobilized on different supports, orientated through different structural features and very likely involving different areas of its surface. For example, three industrial enzymes (penicillin G acylase, lipase, and beta-galactosidase) could be immobilized through different strategies yielding immobilized derivatives with very different activities. The best derivatives preserved 75-100% of activity corresponding to the soluble enzymes used for immobilization, while in some cases a particular immobilization protocol promoted the full inactivation of the enzyme.

One-step purification, covalent immobilization, and additional stabilization of poly-His-tagged proteins using novel heterofunctional chelate-epoxy supports

Epoxy supports covalently immobilize proteins following a two-step mechanism; that is, the protein is physically adsorbed and then the covalent reaction takes place. This mechanism has been exploited to combine the selectivity of metal chelate affinity chromatography with the covalent immobilization capacity of epoxy supports. In this way, it has been possible to accomplish, in a simple manner, the purification, immobilization, and stabilization of a poly-His-tagged protein. To fulfill this objective we developed a new kind of multifunctional epoxy support (chelate epoxy support [CES]), which was tested using a poly-His-tagged glutaryl acylase as a model protein (an alphabeta-heterodimeric enzyme of significant industrial interest). The selectivity of the immobilization in CES toward poly-His-tagged proteins was dependent to a large extent on the density and nature of the chelated metal. The highest selectivity was achieved by using low-density chelate groups (e.g., 5 micromol/g) and metals with a low affinity (e.g., Co). However, the rate of covalent immobilization of the protein by its reaction with the epoxy groups on the support significantly increased at alkaline pH values. The multipoint attachment to the CES also depended on the reaction time. The immobilization of both glutaryl acylase subunits was achieved by incubation of the enzyme derivative at pH 10 for 24 h, with the best enzyme derivative 100-fold more stable than the soluble enzyme. By taking advantage of the selectivity properties of the novel support, we were able to immobilize up to 30 mg of protein per gram of modified Eupergit 250 using either pure enzyme or a very crude enzyme extract.

Modulation of penicillin acylase properties via immobilization techniques: one-pot chemoenzymatic synthesis of Cephamandole from Cephalosporin C

The modulation of penicillin G acylase (PGA) properties via immobilization techniques has been performed studying the acylation of 7-aminocephalosporanic acid with R-mandelic acid methyl ester. PGA from Escherichia coli, immobilized onto agarose activated with glycidol (glyoxyl-agarose), has been used for the design of a novel one-pot synthesis of Cephamandole in aqueous medium and without isolation of intermediates, through three consecutive biotransformations catalyzed by D-amino acid oxidase, glutaryl acylase and PGA.

Affinity chromatography of polyhistidine tagged enzymes. New dextran-coated immobilized metal ion affinity chromatography matrices for prevention of undesired multipoint adsorptions

New immobilized metal ion affinity chromatography (IMAC) matrices containing a high concentration of metal-chelate moieties and completely coated with inert flexible and hydrophilic dextrans are here proposed to improve the purification of polyhistidine (poly-His) tagged proteins. The purification of an interesting recombinant multimeric enzyme (a thermoresistant beta-galactosidase from Thermus sp. strain T2) has been used to check the performance of these new chromatographic media. IMAC supports with a high concentration (and surface density) of metal chelate groups promote a rapid adsorption of poly-His tagged proteins during IMAC. However, these supports also favor the promotion of undesirable multi-punctual adsorptions and problems may arise for the simple and effective purification of poly-His tagged proteins: (a) more than 30% of the natural proteins contained in crude extracts from E. coli become adsorbed, in addition to our target recombinant protein, on these IMAC supports via multipoint weak adsorptions; (b) the multimeric poly-His tagged enzyme may become adsorbed via several poly-His tags belonging to different subunits. In this way, desorption of the pure enzyme from the support may become quite difficult (e.g., it is not fully desorbed from the support even using 200 mM of imidazole). The coating of these IMAC supports with dextrans greatly reduces these undesired multi-point adsorptions: (i) less than 2% of natural proteins contained in crude extracts are now adsorbed on these novel supports; and (ii) the target multimeric enzyme may be fully desorbed from the support using 60 mM imidazole. In spite of this dramatic reduction of multi-point interactions, this dextran coating hardly affects the rate of the one-point adsorption of poly-His tagged proteins (80% of the rate of adsorption compared to uncoated supports). Therefore, this dextran coating of chromatographic matrices seems to allow the formation of strong one-point adsorptions that involve small areas of the protein and support surface. However, the dextran coating seems to have dramatic effects for the prevention of weak or strong multipoint interactions that should involve a high geometrical congruence between the enzyme and the support surface.

Immunogenetic analysis of variable regions encoding AB1 and gamma-type AB2 antibodies from the NeuGc-containing ganglioside family

The variable regions from P3, a murine monoclonal antibody (MAb) against NeuGc-containing gangliosides, and two anti-idiotype MAbs directed to P3 MAb were cloned and sequenced. Comparisons with previously reported sequences showed that P3 is a germline antibody encoded by genes from the V(H)Q52 and V(kappa)19 families. Analysis of nucleotides at the heavy chain CDR3 (H-CDR3) showed the presence of an extensive 3' N region that contains almost 50% of the nucleotides of this CDR. In addition, amino acid sequence analysis of the H-CDRs of this MAb revealed the presence of three arginines, two of which are present in the H-CDR3, that could be involved in the interaction of P3 MAb with its electronegative epitope on gangliosides. Anti-idiotype 1E10, which seems to define a "regulatory" idiotope on P3 MAb (it induces Id+ Ab3), represents a germline Ab2 that belongs to the V(H)J558 and V(kappa)10 gene families. By contrary, the anti-idiotype 3B11 is an extensively mutated antibody that belongs to the V(H)3660 and V(kappa)4/5 gene families, defining a "private" idiotope on P3 MAb. Even when different V genes contribute to the variable regions of 1E10 and 3B11 MAbs, they share an acidic motif E/D-D-Y/D-Y-D in H-CDR3, suggesting that both Ab2s recognize paratope positive residues on the Ab1. Therefore, complementary electrostatic interactions involving H-CDR3 from both Ab1 and Ab2, might provide a clue to understand the molecular basis for the generation of gamma-type anti-idiotype antibodies to V regions recognizing glycolylated ganglioside antigens.

Intramolecular C-H activation by alkylpalladium(II) complexes: insights into the mechanism of the palladium-catalyzed arylation reaction

The cyclization of [ArOCH2PdL2Cl] complexes proceeds at room temperature in CH3CN in the presence of base, such as KOPh or carbonate, to form palladacycles. The effect of substituents on the aryl moiety (p-MeO > H >p-NO2) is as expected for an electrophilic aromatic substitution by electrophilic Pd(II). The absence of isotopic effect is also consistent with this proposal. Cyclopalladation proceeds with bidentate ligands (dppf, COD and phen); although the C-H activation reactions are slower in these cases. The starting [ArOCH2Pd(PPh3)2Cl] and [ArOCH2Pd(PPh3)Cl]2 complexes were prepared by transmetalation of organostannanes [(ArOCH2)4Sn] with [Pd(PPh3)2Cl2] or [Pd(PPh3)Cl2]2, respectively. Cleavage of palladacycles with HCl also gave [ArOCH2PdL2Cl] complexes.

Coimmobilization of L-asparaginase and glutamate dehydrogenase onto highly activated supports

In the present research work, production of coimmobilized derivatives of L-asparaginase and glutamate dehydrogenase was attempted. Comparison of immobilization of each enzyme independently with coimmobilization of the two enzymes unfolded important advantages of the latter, namely a decrease in the induction period (time before the maximum reaction rate is virtually achieved) and an increase in the maximum reaction rate. The effectiveness of the independent enzyme derivatives was low; however, it was enhanced by three-fold when the enzymes were coimmobilized onto the same agarose-glutaraldehyde support. Each supporting agarose bead may in fact be viewed as a nano-reactor with in situ reaction and separation (i.e. elimination of the ammonia formed), with the nanoenvironment surrounding each enzyme molecule being essentially devoid of steric hindrance.

Structural and functional stabilization of L-asparaginase via multisubunit immobilization onto highly activated supports

A new protocol for the stabilization of the quaternary structure of multimeric enzymes has been attempted using as model enzyme (tetrameric) L-asparaginase from Escherichia coli. Such strategy is based upon multisubunit covalent immobilization of the enzyme onto activated supports (agarose-glutaraldehyde). Supports activated with different densities of reactive groups were used; the higher the density of groups, the higher the stabilization attained. However, because of the complexity of that enzyme, even the use of the highest densities of reactive groups was not enough to encompass all four subunits in the immobilization process. Therefore, a further chemical intersubunit cross-linking with aldehyde-dextran was pursued; these derivatives displayed a fully stabilized multimeric structure. In fact, boiling the modified enzyme derivative in the presence of sodium dodecyl sulfate and beta-mercaptoethanol did not lead to release of any enzyme subunit into the medium. Such a derivative, prepared under optimal conditions, retained ca. 40% of the intrinsic activity of the free enzyme and was also functionally stabilized, with thermostabilization enhancements of ca. 3 orders of magnitude when compared with its soluble counterpart. This type of derivative may be appropriate for extracorporeal devices in the clinical treatment of acute leukemia and might thus bring about inherent advantages in that all subunits are covalently bound to the support, with a longer half-life and a virtually nil risk of subunit release into the circulating blood stream.

Modulation of lipase properties in macro-aqueous systems by controlled enzyme immobilization: enantioselective hydrolysis of a chiral ester by immobilized Pseudomonas lipase

Lipase from Pseudomonas fluorescens (PFL) has been immobilized by using different immobilization protocols. The catalytic behavior of the different PFL derivatives in the hydrolytic resolution of fully soluble (R,S) 2-hydroxy 4-phenyl butanoic acid ethyl ester (HPBE) in aqueous medium was analyzed. The soluble enzyme showed a significant but low enantioselectivity, hydrolyzing the S isomer more rapidly than the R-isomer (E = 7). The enzyme, immobilized via a limited attachment to a long and flexible spacer arm, showed almost identical activity and specificity to the soluble enzyme. However, other derivatives, e.g. PFL adsorbed on supports covered by hydrophobic moieties (octyl, decaoctyl), exhibited significant hyperactivation on immobilization (approximately 7-fold). Simultaneously, the enantioselectivity of the PFL-immobilized enzyme was significantly improved (from E = 7 to E = 80). By using such derivatives, almost pure R ester isomer (e.e. > 99%) has been obtained after 55% hydrolysis of the racemic mixture of a solution of 10% (w/v) (R,S) HPBE. The derivatives could be used for 10 cycles without any significant decrease in the activity of the biocatalyst.

Formation of benzo[b]fluorenes and the benzo[a]fluorene core of the fluostatins by cyclization of diaryldiynones

[figure: see text] Thermal cyclization of 1-[2-(trimethylsilylethynyl)phenyl]-3-arylpropinones was expected to give benzo[b]fluorenones. However, benzo[a]-fluorenones were also formed as a result of a new rearrangement. These tetracycles possess the core structure of the fluostatins and isoprekinamycin.

Removal of amphipathic epitopes from genetically engineered antibodies: production of modified immunoglobulins with reduced immunogenicity

Several approaches have been developed to reduce the human immune response to nonhuman antibodies. However, chimeric antibodies and humanized antibodies often have decreased binding affinity. We described a new approach for reducing the immunogenicity of chimeric antibodies while maintaining the affinity. This approach seeks to prevent the recognition of murine immunogenic peptides from the antibody variable region by human lymphocytes. Putative immunogenic epitopes in the variable region are identified and subjected to site directed mutagenesis to make them human and/or to break the amphipathic motifs. The R3 antibody, which blocks the epidermal growth factor (EGF) receptor, was used as a model system to test this approach. Four segments containing possible amphipathic epitopes were found in the heavy variable domain using the program AMPHI. Six amino acids within two of these segments were substituted by the corresponding residues from a homologous human sequence. No mutations were made in the murine light variable domain. Experiments in monkeys suggested that the "detope" R3 antibody was less immunogenic than its chimeric analogue. A search for possible amphipathic epitopes in the Kabat database revealed the presence of conserved patterns in the different families of variable region sequences, suggesting that the proposed method may be of general applicability.

Hepatocyte growth factor in vitreous and serum from patients with proliferative diabetic retinopathy

BACKGROUND

Hepatocyte growth factor (HGF) is an endothelium specific growth factor that has been implicated in angiogenesis, a crucial event for the development of proliferative diabetic retinopathy (PDR). The aim of the study is to determine the intravitreous concentrations of HGF in diabetic patients with PDR, and to investigate whether its serum levels could contribute to its intravitreous concentration.

METHODS

17 diabetic patients and seven non-diabetic patients in whom a vitrectomy was performed were studied. Both groups were matched by serum levels of HGF. Venous blood and vitreous samples were collected simultaneously at the time of vitreoretinal surgery. Vitreous and serum HGF were determined by ELISA.

RESULTS

Intravitreous concentrations of HGF (median and range) were higher in diabetic patients (17.04 ng/ml (9.98-80)) in comparison with non-diabetic patients (5.88 ng/ml (2.57-14.20); p=0. 003). Intravitreous HGF concentrations were strikingly higher than serum HGF concentrations both in diabetic patients (17.04 ng/ml (9. 98-80) v 0.66 ng/ml (0.26-1.26); p<0.001) and in the control group (5.88 ng/ml (2.57-14.20) v 0.68 ng/ml (0.49-0.96); p=0.003). No correlation was found between serum and vitreous levels of HGF in both groups (diabetic patients, r= -0.31; p=0.5 and control subjects r= -0.15; p=0.5).

CONCLUSION

The high vitreous levels of HGF observed in diabetic patients with PDR cannot be attributed to serum diffusion across the blood-retinal barrier. Therefore, intraocular synthesis appears to be the main contributing factor for the high vitreous HGF concentrations in diabetic patients, a cytokine that seems to be directly involved in the pathogenesis of PDR.

Reversible enzyme immobilization via a very strong and nondistorting ionic adsorption on support-polyethylenimine composites

New tailor-made anionic exchange resins have been prepared, based on films of large polyethylenimine polymers (e.g., MW 25,000) completely coating, via covalent immobilization, the surface of different porous supports (agarose, silica, polymeric resins). Most proteins contained in crude extracts from different sources have been very strongly adsorbed on them. Ionic exchange properties of such composites strongly depend on the size of polyethylenimine polymers as well as on the exact conditions of the covalent coating of the solids with the polymer. On the contrary, similar coating protocols yield similar matrices by using different porous supports as starting material. For example, 77% of all proteins contained in crude extracts from Escherichia coli were adsorbed, at low ionic strength, on the best matrices, and less than 15% of the adsorbed proteins were eluted from the support in the presence of 0.3 M NaCl. Under these conditions, 100% of the adsorbed proteins were eluted from conventional DEAE supports. Such polyethylenimine-support composites were also very suitable to perform very strong and nondistorting reversible immobilization of industrial enzymes. For example, lipase from Candida rugosa (CRL), beta-galactosidase from Aspergillus oryzae and D-amino acid oxidase (DAAO) from Rhodotorula gracilis, were adsorbed on such matrices in a few minutes at pH 7.0 and 4 degrees C. Immobilized enzymes preserved 100% of catalytic activity and remained fully immobilized in 0.2 M NaCl. In addition to that, CRL and DAAO were highly stabilized upon immobilization. Stabilization of DAAO, a dimeric enzyme, seems to be due to the involvement of both enzyme subunits in the ionic adsorption.

Increase in conformational stability of enzymes immobilized on epoxy-activated supports by favoring additional multipoint covalent attachment*

Epoxy supports (Eupergit C) may be very suitable to achieve the multipoint covalent attachment of proteins and enzymes, therefore, to stabilize their three-dimensional structure. To achieve a significant multipoint covalent attachment, the control of the experimental conditions was found to be critical. A three-step immobilization/stabilization procedure is here proposed: 1) the enzyme is firstly covalently immobilized under very mild experimental conditions (e.g. pH 7.0 and 20 degrees C); 2) the already immobilized enzyme is further incubated under more drastic conditions (higher pH values, longer incubation periods, etc.) to "facilitate" the formation of new covalent linkages between the immobilized enzyme molecule and the support; 3) the remaining groups of the support are blocked to stop any additional interaction between the enzyme and the support. Progressive establishment of new enzyme-support attachments was showed by the progressive irreversible covalent immobilization of several subunits of multi-subunits proteins (all non-covalent structures contained in crude extracts of different microorganism, penicillin G acylase and chymotrypsin). This multipoint covalent attachment enabled the significant thermostabilization of two relevant enzymes, (compared with the just immobilized derivatives): chymotrypsin (5-fold factor) and penicillin G acylase (18-fold factor). Bearing in mind that this stabilization was additive to that achieved by conventional immobilization, the final stabilization factor become 100-fold comparing soluble penicillin G acylase and optimal derivative. These stabilizations were observed also when the inactivations were promoted by the enzyme exposure to drastic pH values or the presence of cosolvents.

[Quality of antihypertensive drug prescription in a health area]

OBJECTIVE

To find the compliance with previously established criteria on the quality of prescription of medication for hypertension.

DESIGN

Retrospective and concurrent evaluation study of scientific and technical quality, with processing data, using as data source the clinical history.

SETTING

Primary care teams in a Madrid Health Area.

PARTICIPANTS

873 clinical histories of hyper-intense patients in treatment with diuretics, beta-blockers, ACE inhibitors and/or calcium antagonists were chosen through systematic probabilistic sampling with a randomised start.

MEASUREMENTS AND MAIN RESULTS

Data on age, sex, recording of treatment, linked pathologies and situations conditioning the choice of medicine were gathered. Information on the defined use criteria of the various pharmacological groups was also collected. 1145 drugs were used on 873 patients. Most common were the thiazide diuretics (36%), followed by ACE inhibitors (34.4%), calcium antagonists (21%) and beta-blockers (8.6%). 72% of the patients were undergoing one single therapy. 89.7% of the cases (95% CI, 87.43-91.59) had the treatment correctly recorded in the clinical record. Of the 721 hyperintense patients over 59 years old, 70.3% (95% CI, 66.81-73.60) fitted the defined criterion for use of diuretics. 48.7% fitted the ACE inhibitor criteria defined (CI, 43.71-53.78); 85.7% the beta-blocker criteria (CI, 76.85-91.69); and 58.7% the calcium antagonist criteria (95% CI, 52.17-64.9).

CONCLUSIONS

The fit of the use of diuretics with the defined quality criterion is acceptable, while in the cases of ACE inhibitors and calcium antagonists the quality of prescription could be improved, while the use of beta-blockers is minimal.

Serum laminin as a marker of diabetic retinopathy development: a 4-year follow-up study

PURPOSE

The usefulness of laminin as a serum marker of diabetic retinopathy is a topic that generates conflicting views. The aim of the present study was to investigate the effect of diabetic retinopathy on serum laminin-P1, the larger pepsin resistant fragment of laminin, and to elucidate whether serum laminin-P1 could be an indicator of the risk for development of diabetic retinopathy.

METHODS

In a prospective study, 97 consecutive diabetic patients (35 type 1 and 62 type 2) without diabetic retinopathy and a urinary albumin excretion rate lower than 20 microg per minute were enrolled in a 4-year follow-up study. Patients who developed microalbuminuria during the study were excluded in order to avoid the influence of diabetic nephropathy on serum laminin-P1. At the end of follow-up, data from ophthalmologic studies and serum laminin-P1 were evaluated in the 66 normoalbuminuric diabetic patients who completed the study.

RESULTS

No statistical differences were observed in baseline laminin-P1 serum concentrations between patients who developed diabetic retinopathy (n = 15) and patients who remained without it during follow-up (n = 51). However, serum laminin-P1 levels obtained at the end of the study were significantly higher in patients who developed diabetic retinopathy (1.75 +/- 0.33 U/ml versus 1.47 +/- 0. 27 U/ml; P =.002). Furthermore, statistical difference was observed when initial and final values of serum laminin-P1 were compared in patients who developed diabetic retinopathy (1.56 +/- 0.27 U/ml versus 1.75 +/- 0.33 U/ml; P =.001). Remarkably, an increase in serum laminin-P1 concentration was detected in all but two of the patients who developed diabetic retinopathy. The relative risk of development of diabetic retinopathy in patients who showed an increase in serum laminin-P1 during follow-up was 5.4 (95% confidence interval, 1.32 to 22.13).

CONCLUSIONS

Serum laminin-P1 is a marker and a risk indicator of diabetic retinopathy but is not an early predictor of its development.

Vitreous levels of IGF-I, IGF binding protein 1, and IGF binding protein 3 in proliferative diabetic retinopathy: a case-control study

OBJECTIVE

To evaluate vitreous levels of IGF-I and its binding proteins IGFBP-1 and IGFBP-3 in patients with proliferative diabetic retinopathy (PDR). Because intravitreal proteins are elevated in patients with PDR due to the disruption of the blood-retinal barrier, we have corrected vitreal IGF-I and IGFBPs by total vitreal proteins to avoid this confounding factor.

RESEARCH DESIGN AND METHODS

We compared 21 diabetic patients with proliferative retinopathy (group A) and 13 nondiabetic patients (group B) in whom a vitrectomy was performed. Both groups were matched by age, serum IGF-I, IGFBP-1, and IGFBP-3 levels. Serum and vitreous levels of IGF-I, IGFBP-1, and IGFBP-3 were measured by immunological methods. Vitreal proteins were assessed by turbidimetric method.

RESULTS

Vitreal levels of IGF-I were elevated in group A (median 1.35 ng/ml [range 0.3-8.7]) in comparison with group B (median 0.25 ng/ml [range 0-1.38]), P<0.001. After adjusting by vitreal proteins [ratio IGF-I (ng/ml)/protein (mg/ml)], the differences remain significant (P<0.005). Vitreal levels of IGFBP-1 and IGFBP-3 were also elevated in diabetic patients (IGFBP-1: group A, median 1.6 ng/ml [range 0.6-20.7]; group B, median 0.4 ng/ml [range 0.3-1.9], P<0.001. IGFBP-3: group A, median 102.6 ng/ml [range 53.9-350.8]; group B, median 29.0 ng/ml [range 3.2-87.8], P<0.001). However, when the ratio IGFBP/protein was considered, the differences were not significant.

CONCLUSIONS

Intraocular synthesis contributes to elevated vitreous concentrations of IGF-I found in PDR. By contrast, unspecific increase of intravitreal proteins is the main factor explaining the elevated vitreous levels of IGFBP-1 and IGFBP-3 found in diabetic patients.

Effect of panretinal photocoagulation on serum levels of laminin in patients with diabetes: a prospective study

BACKGROUND/AIM

Laminin, a major specific non-collagenous glycoprotein of basement membrane, has been proposed as an index of diabetic retinopathy and high serum concentrations have been reported in patients with proliferative diabetic retinopathy. On the other hand, panretinal photocoagulation (PRP) prevents the progression of severe diabetic retinopathy and reverses preretinal neovascularisation. The aim of the study was to investigate the effect of PRP on serum levels of laminin in patients with diabetes.

METHODS

20 patients with diabetes undergoing PRP and 15 patients with mild or moderate non-proliferative diabetic retinopathy in whom a PRP was not performed were included in the study. Serum laminin-P1 (Lam-P1), the largest pepsin resistant fragment of laminin, was determined by radioimmunoassay in each patient before starting PRP and 3 months after it was accomplished. Similarly, a baseline and a 4 month sample were analysed in the non-photocoagulated controls.

RESULTS

Serum Lam-P1 concentrations obtained 3 months after PRP were significantly lower when compared with the initial values (1.62 (SD 0.36) U/ml v 1.91 (0.37) U/ml; p <0.001). A decrease of serum levels of Lam-P1 could be seen in all patients. By contrast, in those patients with mild or moderate non-proliferative diabetic retinopathy in whom a PRP was not performed, no significant changes were detected in serum Lam-P1 concentrations (1.72 (0.20) U/ml v 1. 74 (0.17); p=0.250).

CONCLUSION

PRP decreases serum Lam-P1 levels in patients with severe diabetic retinopathy. Thus, the studies addressed to evaluate the usefulness of Lam-P1 as a marker of diabetic retinopathy should consider previous PRP as an influencing factor. Finally, our results suggest that retinal source of Lam-P1 strongly contributes to serum Lam-P1 in patients with severe diabetic retinopathy.

Selective adsorption of poly-His tagged glutaryl acylase on tailor-made metal chelate supports

A poly-His tag was fused in the glutaryl acylase (GA) from Acinetobacter sp. strain YS114 cloned in E. coli yielding a fully active enzyme. Biochemical analyses showed that the tag did not alter the maturation of the chimeric GA (poly-His GA) that undergoes a complex post-translational processing from an inactive monomeric precursor to the active heterodimeric enzyme. This enzyme has been used as a model to develop a novel and very simple procedure for one-step purification of poly-His proteins via immobilized metal-ion affinity chromatography on tailor-made supports. It was intended to improve the selectivity of adsorption of the target protein on tailor-made chelate supports instead of performing a selective desorption. The rate and extent of the adsorption of proteins from a crude extract from E. coli and of pure poly-His tagged GA on different metal chelate supports was studied. Up to 90% of proteins from E. coli were adsorbed on commercial chelate supports having a high density of ligands attached to the support through long spacer arms, while this adsorption becomes almost negligible when using low ligand densities, short spacer arms and Zn2+ or Co2+ as cations. On the contrary, poly-His GA adsorbs strongly enough on all supports. A strong affinity interaction between the poly-His tail and a single chelate moiety seems to be the responsible for the adsorption of poly-His GA. By contrast, multipoint weak interactions involving a number of chelate moieties seem to be mainly responsible for adsorption of natural proteins. By using tailor-made affinity supports, a very simple procedure for one-step purification of GA with minimal adsorption of host proteins could be performed. Up to 20 mg of GA were adsorbed on each ml of chelate support while most of accompanying proteins were hardly adsorbed on such supports. Following few washing steps, the target enzyme was finally recovered (80% yield) by elution with 50 mM imidazole with a very high increment of specific activity (up to a 120 purification factor).

Pharmacokinetics and retinal toxicity of intravitreal liposome-encapsulated 5-fluorouridine

BACKGROUND

Fluoropyrimidines may be effective in preventing proliferative vitreoretinopathy after repair of complicated retinal detachments. Liposome encapsulation of these antiproliferative drugs may extend the intravitreal half-life and increase their efficacy.

METHODS

The current study evaluated the pharmacokinetic behavior of intravitreally injected 5-fluorouridine (5-FUR), free and encapsulated in liposomes, either conventionally or coated with collagen into 25 New Zealand rabbits. Additionally, we investigated the retinal toxicity of intravitreal injections of 100, 250 and 500 microg as well as 1 mg 5-FUR as free drug or encapsulated in liposomes in the rabbit eye.

RESULTS

The half-life of free 5-FUR after liposome injection into the vitreous cavity was 18.17+/-2.43 h, considerably longer than the half-life of free 5-FUR (0.82 h). Electrophysiologic tests did not show any changes in latency and a-wave amplitude and minimal changes in the b-wave amplitude. Histopathologic studies revealed integrity of the inner limiting membrane, and mild vacuolization in the outer retina.

CONCLUSION

Encapsulation of 5-FUR within liposomes markedly increases its intravitreal half-life. Our study suggests that liposome-encapsulated 5-FUR is not toxic to the retina even at doses of 1 mg.

Vitreous levels of vascular endothelial growth factor are not influenced by its serum concentrations in diabetic retinopathy

Vascular endothelial growth factor (VEGF) plays a major role in the development of neovascularization in proliferative diabetic retinopathy (PDR). The source of intravitreous VEGF is presumably ischaemic retina, but increased levels derived from serum cannot be excluded. The aim of the study is to determine the intravitreous concentrations of VEGF in diabetic patients with PDR and to investigate whether serum VEGF could contribute to the intravitreous concentration. For this purpose, we studied 20 diabetic patients (5 IDDM and 15 NIDDM) with PDR in whom a vitrectomy was performed (group A). Non-diabetic patients (n = 13) with other conditions requiring vitrectomy served as a control group (group B). In both groups, VEGF was determined in serum and undiluted vitreous samples obtained simultaneously. Furthermore, serum VEGF was determined in 69 healthy control subjects (group C) and 39 diabetic patients without microvascular complications (group D). Vitreous and serum VEGF was determined by ELISA (R & D Systems, Abingdon, UK); intra-assay CV 3.8%, interassay CV 5.1%. Intravitreous concentrations of VEGF were strikingly higher in group A (median 1.75 ng/ ml, range 0.33-6.66) in comparison with group B (median 0.009 ng/ml, range 0.009-0.038); p < 0.0001. This difference remained significant after adjusting for intravitreous protein concentration (p < 0.05). Differences in serum VEGF among the groups included in the study were not found. We conclude that the high vitreous levels of VEGF observed in diabetic patients with PDR cannot be attributed to serum diffusion across the blood-retinal barrier. Therefore, intraocular synthesis is the main contributing factor for the high vitreous VEGF concentrations observed in PDR.

Intrathecal morphine for postoperative analgesia following repair of frontal encephaloceles in children: comparison with intermittent, on-demand dosing of nalbuphine

STUDY OBJECTIVE

To determine the efficacy of lumbar intrathecal (i.t.) morphine in a dose of 0.02 mg/kg in providing analgesia following repair of frontal encephaloceles.

DESIGN

Prospective, open-label investigation of i.t. morphine with secondary comparison to a retrospective cohort.

SETTING

Metropolitan hospital in the Philippines.

PATIENTS

24 ASA physical status I and II children undergoing frontal encephalocele repair.

INTERVENTIONS

Following induction of general anesthesia. I.t. morphine (Group 1) was administered via single-shot technique or through a lumbar i.t. drain placed for cerebrospinal fluid drainage during the surgical procedure. Postoperative analgesia was assessed by visual analog score in patients greater than 5 years of age or a behavioral score in patients less than 5 years of age. The retrospective cohort received postoperative analgesia with intermittent doses of intravenous nalbuphine (Group 2).

MEASUREMENTS AND MAIN RESULTS

Group 1 had decreased postoperative analgesic requirements, decreased intraoperative inhalational anesthetic requirements, and a longer time to the first request for postoperative analgesia than Group 2. The time to the first request for postoperative analgesia was 16.0 +/- 9.1 hours in Group 1 and 1.6 +/- 1.2 hours in Group 2 (p < 0.0001). Six of 12 patients in Group 1 required no analgesic drugs during the first 24 postoperative hours while all 12 patients in Group 2 (p = 0.02) did require analgesic drugs during this period. The patients in Group 1 who did not require supplemental analgesic drugs maintained pain scores of 2 or less throughout the first 24 postoperative hours.

CONCLUSION

Lumbar IT morphine provides effective analgesia following repair of frontal encephaloceles in children and adolescents.

Humanization of a mouse monoclonal antibody that blocks the epidermal growth factor receptor: recovery of antagonistic activity

BACKGROUND

Antibody humanization by transplanting the complementarity determining regions (CDRs) of a murine antibody to a human framework aims to reduce the response of the human immune system against a foreign molecule. Frequently, however, some murine amino acids from the framework have to be retained to recover binding affinity.

OBJECTIVES

To redesign R3, a mouse monoclonal antibody (mAb) that binds the human epidermal growth factor (EGF)-receptor and inhibits the binding of EGF, to be a human IgG1.

STUDY DESIGN

The light and heavy chains of REI and Eu, respectively, were selected as human immunoglobulin (Ig) frameworks for CDR-grafting based on their high homology with the corresponding sequences of murine R3. Molecular modeling was used to analyze the possible effects of mutating murine residues that underlie the CDRs.

RESULTS

CDR-grafting dramatically reduced the binding capability of the antibody. Molecular modeling suggested that two amino acids (Thr 76 and Thr 93), among five immunoglobulin heavy chain variable region (VH) residues underlying the CDRs, were critical for antigen binding. The five residues were mutated back to the original murine amino acids in different combinations contained in six variants of humanized antibodies. In agreement with molecular modeling analysis. The variant in which three murine residues were retained (Ser 75, Thr 76 and Thr 93) exhibited a similar capacity to inhibit the binding of 125I-labeled EGF to its receptor as compared with the original antibody. This humanized antibody was at least 2-fold less immunogenic in African Green monkeys than the chimeric antibody.

CONCLUSIONS

Only very few mutations in the frameworks may be necessary to recover the binding capability of a humanized antibody. Molecular modeling can serve as a powerful tool to identify residues critical for binding.