Phase II study of gemcitabine, oxaliplatin in combination with panitumumab in KRAS wild-type unresectable or metastatic biliary tract and gallbladder cancer.

BACKGROUND: Current data suggest that platinum-based combination therapy is the standard first-line treatment for biliary tract cancer. EGFR inhibition has proven beneficial across a number of gastrointestinal malignancies; and has shown specific advantages among KRAS wild-type genetic subtypes of colon cancer. We report the combination of panitumumab with gemcitabine (GEM) and oxaliplatin (OX) as first-line therapy for KRAS wild-type biliary tract cancer. METHODS: Patients with histologically confirmed, previously untreated, unresectable or metastatic KRAS wild-type biliary tract or gallbladder adenocarcinoma with ECOG performance status 0-2 were treated with panitumumab 6 mg kg(-1), GEM 1000 mg m(-2) (10 mg m(-2) min(-1)) and OX 85 mg m(-2) on days 1 and 15 of each 28-day cycle. The primary objective was to determine the objective response rate by RECIST criteria v.1.1. Secondary objectives were to evaluate toxicity, progression-free survival (PFS), and overall survival. RESULTS: Thirty-one patients received at least one cycle of treatment across three institutions, 28 had measurable disease. Response rate was 45% and disease control rate was 90%. Median PFS was 10.6 months (95% CI 5-24 months) and median overall survival 20.3 months (95% CI 9-25 months). The most common grade 3/4 adverse events were anaemia 26%, leukopenia 23%, fatigue 23%, neuropathy 16% and rash 10%. CONCLUSIONS: The combination of gemcitabine, oxaliplatin and panitumumab in KRAS wild type metastatic biliary tract cancer showed encouraging efficacy, additional efforts of genetic stratification and targeted therapy is warranted in biliary tract cancer.

Evaluation of the activated partial thromboplastin time assay for clinical monitoring of PEGylated recombinant factor VIII (BAY 94-9027) for haemophilia A.

Patients with haemophilia (PWH) are usually monitored by the one-stage activated partial thromboplastin time (aPTT) factor VIII (FVIII) assay. Different aPTT activators may affect clotting time (CT) and FVIII:C levels in patients treated with PEGylated FVIII. To evaluate the characteristics of PEGylated FVIII (BAY 94-9027) in various aPTT clotting assays, and to identify suitable aPTT reagents for monitoring BAY 94-9027 during the treatment of PWH, BAY 94-9027 and World Health Organization (WHO) 8th FVIII standards (WHO-8) were spiked into pooled and individual severe haemophilia A plasma at 1.0, 0.25 and 0.05 IU mL(-1) . Five commercial aPTT reagents widely used in clinical laboratories were compared and evaluated for BAY 94-9027 activity in plasma from PWH. BAY 94-9027 and WHO-8 bestowed similar CT and excellent precision when ellagic acid (SynthAFax, Dade Actin, and Cephascreen) aPTT reagents were used. In contrast, BAY 94-9027 showed significantly prolonged CT and poor precision compared with WHO-8 using silica aPTT reagents (APTT-SP and STA PTT 5). Furthermore, free 60-kDa polyethylene glycol (PEG), used for the conjugation of FVIII, showed a dose-dependent prolongation of CT in the APTT-SP assay. There was no effect on the SynthAFax-APTT, prothrombin time, or FXIa-initiated thrombin generation assay, demonstrating that the PEG moiety on FVIII has no general effect on the coagulation cascade. In summary, ellagic aPTT reagents (SynthAFax, Dade Actin, and Cephascreen) are most suitable for evaluating potency of BAY 94-9027 and should be the preferred aPTT reagents used in clinical laboratories for monitoring FVIII activity after infusion of BAY 94-9027 to PWH.

von Willebrand factor contributes to longer half-life of PEGylated factor VIII in vivo.

PEGylation of B-domain deleted factor VIII (PEG-FVIII-BDD) prolongs the half-life of the molecule by approximately twofold in animals (Mei et al., Blood 2010; 116: 270). To investigate the role of von Willebrand factor (vWF) in the catabolism of PEG-FVIII-BDD in vivo, a FVIII-BDD mutant (F8V), which is incapable of binding vWF, was generated by deleting the vWF-binding region in the a3 domain of FVIIII-BDD. F8V was expressed, purified and PEGylated by site-specific conjugation. The biochemical and biological properties of F8V and PEGylated F8V (PEG-F8V) were evaluated in vitro and in vivo. The specific activity of purified F8V by a chromogenic assay was similar to FVIII-BDD and PEGylation had minimal impact on the specific activity of F8V in this assay. Analysis by Biacore indicated that both F8V and PEG-F8V display greatly reduced vWF binding in vitro. Pharmacokinetic studies in FVIII knockout (HaemA) mice showed that the terminal half-life (T1/2 ) of F8V was dramatically reduced relative to FVIII-BDD (0.6 h vs. 6.03 h). PEGylation of F8V promoted a significant increase in T1/2 , although PEGylation did not fully compensate for the loss in vWF binding. PEG-F8V showed a shorter T1/2 than PEG-FVIII-BDD both in HaemA mice (7.7 h vs. 14.3 h) and in Sprague-Dawley male rats (2.0 ± 0.3 h vs. 6.0 ± 0.5 h). These data demonstrated that vWF contributes to the longer T1/2 of PEG-FVIII-BDD. Furthermore, this suggests that the clearance of the FVIII:vWF complex, through vWF receptors, is not the sole factor which places an upper limit on the duration of PEG-FVIII circulation in plasma.

Comparative effectiveness of adding Omega-3 or Vitamin D to standard therapy in preventing and treating episodes of painful crisis in pediatric sickle cell patients.

OBJECTIVE: Sickle Cell Anemia (SCA), also called the Sickle Cell Disease (SCD), is an inherited hematological disorder characterized by a syndrome of acute anemia and a painful crisis. The sickling hemoglobin, Hgb-S causes viscosity and inflammation of blood vessels. Eventually, the red blood cells get eliminated from the circulation process, which leads to hemolytic anemia. This study examined the comparative effectiveness of supplementation of Omega-3 or vitamin-D to standard therapy (hydroxyurea + Ibuprofen) used for prevention and treatment of pain crises in pediatric patients living with SCD. PATIENTS AND METHODS: 165 patients participated in this randomized, double-blind, standard therapy-controlled, parallel-design trial. The patients were randomly divided into three groups, receiving three capsules of either 1,000 mg Omega-3 fish oil (400 mg EPA and 300 mg DHA) or 1.5 mL vitamin-D (2,800 IU/7 ml) daily for 10 months plus the standard therapy. Lactate dehydrogenase, high-density lipoprotein (HDL), low-density lipoprotein (LDL), hematocrit, reticulocyte count, and white-blood-cell count were determined at baseline (month zero) and end of the 10th month. The pain severity was measured using the visual analog scale method (VAS). Therefore, a 10-cm ruler with a VAS design was used to determine the patient pain intensity. The baseline time point was defined as the time spot before starting to deliver the experimental medication to the patients (month zero). At that time, the biodata of the patient on the frequency of pain episodes and the rest of the variables were collected, and the baseline data were one-year retrospective data. RESULTS: Of 165 patients enrolled in the trial, 150 were included in the final analysis. At the end of the study, there was a significant increase in serum LDL and HDL in the Omega-3 group as compared with the control group (mean of 82 mg/dL vs. 57 mg/dL; p < 0.01 and mean of 47 mg/dL vs. 43 mg/dL; p < 0.028, respectively). Other laboratory parameters were significantly influenced. The number of painful crises and pain levels was significantly decreased in the Omega-3 group compared with the control group (mean of one-episode vs. mean of three episodes; p = 0.01, mean of three on pain scale vs. six on pain scale; p = 0.018). CONCLUSIONS: Results showed that Omega-3 was more effective than vitamin-D or standard treatment alone relative to pain crises and most of the other studied items. Vitamin-D was more effective than standard therapy alone. Clinicians should consider the addition of Omega-3 supplements to the standard therapy and a de-escalation dose plan for the hydroxyurea medication.

Cost-effectiveness analysis of adding omega-3 or vitamin D supplementation to standard therapy in treating painful crises of pediatric sickle cell disease patients.

OBJECTIVE: Painful crises represents a predominant complication of sickle cell disease (SCD). The only approved treatments for painful crises in many countries are hydroxyurea plus potent analgesics. Our earlier clinical trial concluded that omega-3 and vitamin D had a potential therapeutic impact on painful crises. However, there is limited research evaluating their therapeutic applications and cost-effectiveness. This paper aims at comparing the cost-effectiveness of omega-3 and vitamin D supplementation to the standard therapy in treating painful crises among children with SCD. PATIENTS AND METHODS: Cost-effectiveness analyses of daily supplementation of omega-3 and vitamin D were performed. The economic evaluation was based on data derived from a prospective 10-month randomized clinical trial (n = 165 patients; 15 patients dropped). 50 patients were recruited into the omega-3 + standard therapy group (hydroxyurea and folic acid daily with ibuprofen as needed), 50 patients into the vitamin D + standard therapy group, and 50 patients receiving standard therapy alone served as a control group. Outcome measures from the randomized clinical trial were used to determine incremental effectiveness. Cost estimates were calculated from the healthcare payer's perspective. The analysis considered the improvement in various outcome measures and are presented here as percent change from baseline to determine the incremental effectiveness and the incremental cost for the treatment of both interventions. RESULTS: Adding omega-3 or vitamin D to the standard therapy was more cost-effective than standard treatment alone. Vitamin D was a cheaper but less cost-effective alternative for most outcomes between the two treatments, including LDL-C and HDL-C. It was also more cost-effective but less clinically effective in reducing vaso-occlusive crisis episodes and pain severity. Omega-3 supplementation was significantly more cost-effective than vitamin D supplementation and the standard treatment for those measures. CONCLUSIONS: The present study showed that using vitamin D and omega-3 as add-on treatments for a painful crisis in pediatric sickle cell disease could have overall cost-saving and clinical benefits. However, further studies with a longer treatment duration are needed to establish more significant effects of the interventions for better policy and clinical decision-making.

Nanoparticle shape and configuration analysis by transmission electron tomography.

Tomographic reconstruction by transmission electron microscopy is used to reveal three-dimensional nanoparticle shapes and the stacking configurations of nanoparticle ensembles. Reconstructions are generated from bright-field image tilt series, with a sample tilt range up to +/- 70 degrees, using single or dual tilt axes. We demonstrate the feasibility of this technique for the analysis of nanomaterials, using appropriate acquisition conditions. Tomography reveals both cubic and hexagonal close-packing configurations in multi-layered arrays of size-selected In nanospheres. By tomography and phase-contrast lattice imaging, we relate the three-dimensional shape of PbSe octahedral nanoparticles to the underlying crystal structure. We also confirm simple-cubic packing in multi-layers of PbSe nanocubes and see evidence that the particle shapes have cubic symmetry. The shapes of TiO(2) nanorod bundles are shown by tomographic reconstruction to resemble flattened ellipsoids.

Mitochondrial gene expression changes in cultured human skin cells following simulated sunlight irradiation.

BACKGROUND: Exposure of skin to simulated sunlight irradiation (SSI) has being extensively researched and shown to be the main cause for changes in the skin including changes in cellular function and generation of reactive oxygen species (ROS). This oxidative stress can subsequently exert downstream effects and the subcellular compartments most affected by this oxidative stress are mitochondria. The importance of functional mitochondrial morphology is apparent as morphological defects are related to many human diseases including diabetes mellitus, liver disease, neurodegenerative diseases, aging and cancer. OBJECTIVE: The main objective of this study was to evaluate solar radiation-induced changes in mitochondrial gene expression in human skin cells using a Q-Sun solar simulator to deliver a close match to the intensity of summer sunlight. METHODS: Spontaneously immortalised human skin epidermal keratinocytes (HaCaT) and Human Dermal Fibroblasts (HDFn) were divided into two groups. Group A were irradiated once and Group B twice 7days apart; following irradiation, mitochondrial gene expression was evaluated 1, 4 and 7days post primary exposure for group A and 1, 4, 7 and 14days post-secondary exposure for group B. RESULTS: Both the epidermal and dermal cells displayed significant reduced expression of the genes analysed for mitochondrial morphology and function; however, epidermal cells displayed this reduction post SSI earlier then dermal cells at multiple time points. CONCLUSION: The data presented here reinforces the fact that epidermal cells, while displaying a heightened sensitivity to sunlight, are less prone to changes in gene expression, while dermal cells, which appear to be more resilient are possibly more prone to genomic instability and mitochondrial damage.

A first-in-human study of the safety, tolerability, pharmacokinetics and pharmacodynamics of PF-06741086, an anti-tissue factor pathway inhibitor mAb, in healthy volunteers.

Essentials Tissue factor pathway inhibitor (TFPI) is an antagonist of FXa and the TF-FVIIa complex. PF-06741086 is an IgG1 monoclonal antibody that targets the Kunitz-2 domain of TFPI. Single doses of PF-06741086 were evaluated in a phase 1 study in healthy volunteers. Data from this study support further investigation of PF-06741086 in individuals with hemophilia. SUMMARY: Background Tissue factor pathway inhibitor (TFPI) is a protease inhibitor of the tissue factor-activated factor VII complex and activated FX. PF-06741086 is a mAb that targets TFPI to increase clotting activity. Objectives This study was a randomized, double-blind, sponsor-open, placebo-controlled, single intravenous or subcutaneous dose escalation study to evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of PF-06741086. Patients/Methods Volunteers who provided written informed consent were assigned to cohorts with escalating dose levels. Safety endpoints included treatment-emergent adverse events (TEAEs), infusion/injection site reactions, vital signs, electrocardiogram, and coagulation and hematology laboratory parameters. Pharmacokinetic (PK) and pharmacodynamic (PD) endpoints included exposures of PF-06741086 in plasma and measures of PF-06741086 pharmacology, respectively. Results Forty-one male volunteers were recruited overall. Thirty-two were dosed with PF-06741086 from 30 mg subcutaneously to 440 mg intravenously. All doses were safe and well tolerated. TEAEs were mild or moderate in severity, laboratory abnormalities were transient, there were no serious adverse events, there were no infusion/injection site reactions, and no dose escalation stopping criteria were met. Plasma exposures of PF-06741086 increased greater than proportionally with dose under the same dosing route. Coagulation pharmacology was demonstrated via total TFPI, dilute prothrombin time, D-dimer, prothrombin fragment 1 + 2 and thrombin generation assay parameters. Conclusions Single doses of PF-06741086 at multiple dose levels were safe and well tolerated in a healthy adult male population. The safety, PK and PD data from this study support progression to a multiple-dose study in hemophilic patients.

Early migration of Sarcocystis neurona in ponies fed sporocysts.

Sarcocystis neurona is the most important cause of equine protozoal myeloencephalitis (EPM), a neurologic disease of the horse. In the present work, the kinetics of S. neurona invasion is determined in the equine model. Six ponies were orally inoculated with 250 x 10(6) S. neurona sporocysts via nasogastric intubation and killed on days 1, 2, 3, 5, 7, and 9 postinoculation (PI). At necropsy, tissue samples were examined for S. neurona infection. The parasite was isolated from the mesenteric lymph nodes at 1, 2, and 7 days PI; the liver at 2, 5, and 7 days PI; and the lungs at 5, 7, and 9 days PI by bioassays in interferon gamma gene knock out mice (KO) and from cell culture. Microscopic lesions consistent with an EPM infection were observed in brain and spinal cord of ponies killed 7 and 9 days PI. Results suggest that S. neurona disseminates quickly in tissue of naive ponies.

The Impact of Pathologic Complete Response in Patients with Neoadjuvantly Treated Locally Advanced Rectal Cancer-a Large Single-Center Experience.

Small cohort studies demonstrated better oncologic outcomes for patients with pathologic complete response (PathCR) after neoadjuvant treatment for locally advanced rectal cancer. This study reviews long-term outcomes of a large cohort of clinically stage II/III rectal cancer patients who received neoadjuvant chemoradiation and surgery. This is a retrospective analysis of a single-center cohort, including all clinical stage II/III rectal cancer patients who received neoadjuvant chemoradiation and surgery between 2004 and 2014 (n = 271). Cox regressions were done to assess the influence of PathCR on recurrence-free survival (RFS) and overall survival (OS), adjusting for postoperative chemotherapy, clinical AJCC staging, comorbidity, and age where appropriate. PathCR patients had significantly lower distant recurrence rates (4 vs. 15.8%; P = 0.028) and lower disease-specific mortality rates (0 vs. 8.1%; P = 0.052), compared to patients with residual disease. PathCR was associated with longer RFS (HR, 5.6 [95% CI 1.3-23.1] P = 0.018) and longer OS (HR, 3.4 [1.31-10.0] P = 0.014) compared to having pathological residual disease. This large single-center study shows that patients with PathCR have significant longer RFS and OS than patients with residual disease on pathology after neoadjuvant chemoradiation.

Development and evaluation of a Sarcocystis neurona-specific IgM capture enzyme-linked immunosorbent assay.

Equine protozoal myeloencephalitis (EPM) is a serious neurologic disease of horses caused primarily by the protozoal parasite Sarcocystis neurona. Currently available antemortem diagnostic testing has low specificity. The hypothesis of this study was that serum and cerebrospinal fluid (CSF) of horses experimentally challenged with S neurona would have an increased S neurona-specific IgM (Sn-IgM) concentration after infection, as determined by an IgM capture enzyme linked immunoassay (ELISA). The ELISA was based on the S neurona low molecular weight protein SNUCD-1 antigen and the monoclonal antibody 2G5 labeled with horseradish peroxidase. The test was evaluated using serum and CSF from 12 horses experimentally infected with 1.5 million S neurona sporocysts and 16 horses experimentally infected with varying doses (100 to 100,000) of S neurona sporocysts, for which results of histopathologic examination of the central nervous system were available. For horses challenged with 1.5 million sporocysts, there was a significant increase in serum Sn-IgM concentrations compared with values before infection at weeks 2-6 after inoculation (P < .0001). For horses inoculated with lower doses of S neurona, there were significant increases in serum Sn-IgM concentration at various points in time after inoculation, depending on the challenge dose (P < .01). In addition, there was a significant increase between the CSF Sn-IgM concentrations before and after inoculation (P < .0001). These results support further evaluation of the assay as a diagnostic test during the acute phase of EPM.

Mitochondrial tolerance to single and repeat exposure to simulated sunlight in human epidermal and dermal skin cells.

BACKGROUND: Sunlight represents the primary threat to mitochondrial integrity in skin given the unique nature of the mitochondrial genome and its proximity to the electron transport chain. The accumulation of mitochondrial DNA (mtDNA) mutations is a key factor in many human pathologies and this is linked to key roles of mitochondrial function in terms of energy production and cell regulation. OBJECTIVE: The main objective of this study was to evaluate solar radiation induced changes in mitochondrial integrity, function and dynamics in human skin cells using a Q-Sun solar simulator to deliver a close match to the intensity of summer sunlight. METHODS: Spontaneously immortalised human skin epidermal keratinocytes (HaCaT) and Human Dermal Fibroblasts (HDFn) were divided into two groups. Group A were irradiated once and Group B twice 7days apart and evaluated using cell survival, viability and mitochondrial membrane potential (MMP) and mass at 1, 4 and 7days post one exposure for Group A and 1, 4, 7 and 14days post second exposure for Group B. RESULTS: Viability and survival of HaCaT and HDFn cells decreased after repeat exposure to Simulated Sunlight Irradiation (SSI) with no recovery. HDFn cells showed no loss in MMP after one or two exposures to SSI compared to HaCaT cells which showed a periodic loss of MMP after one exposure with a repeat exposure causing a dramatic decrease from which cells did not recover. Mitochondrial Mass in exposed HDFn cells was consistent with control after one or two exposures to SSI; however mitochondrial mass was significantly decreased in HaCaT cells. CONCLUSION: Data presented here suggests that mitochondria in epidermal cells are more sensitive to sunlight damage compared to mitochondria in dermal cells, despite their origin, confirming a skin layer specific sensitivity to sunlight, but not as expected.

Identification and function probing of an antithrombin IIIß conformation-specific antibody.

UNLABELLED: ESSENTIALS: Antithrombin III (AT)ß binds heparin with higher affinity than ATα. A conformation-specific antibody against ATß, TPP2009, was made to investigate ATß in hemostasis. TPP2009 bound specifically to heparin-ATß and greatly reduced the anticoagulant effect of AT. This antibody was effective in elucidating the importance of ATß in hemostasis. BACKGROUND: Antithrombin III (AT)ß is an isoform of AT that lacks the post-translational carbohydrate modification at Asn135. This isoform binds heparin with greater affinity than ATα, and has been shown to target antithrombotic function to the extracellular vascular endothelial injury site. OBJECTIVES: To characterize a conformation-specific antibody against ATß and begin to investigate the role of ATß in maintaining hemostasis. METHODS: Surface plasmon resonance (SPR), antigen binding and functional assays were conducted to characterize the mode of action of antibodies generated against heparin-bound ATß (ATß*H) by the use of phage display. RESULTS: SPR and binding studies showed that one of the antibodies, TPP2009, bound specifically to ATß*H and glycosaminoglycan-associated ATß on endothelial cells. In diluted prothrombin and activated factor X (FXa)-induced clotting assays, TPP2009 dose-dependently reduced the anticoagulant effect of heparin in non-hemophilic and FVIII-deficient human plasma, with half-maximal effective concentrations (EC50 ) of 10.5 nm and 4.7 nm, respectively. In AT-deficient human plasma, TPP2009 dose-dependently inhibited the effects of exogenously added ATß and heparin. In purified systems with ATß and pentasaccharide, TPP2009 restored > 91% of FXa activity. TPP2009 dose-dependently reversed the effects of heparin in rabbit (EC50 , 25.7 nm) and cynomolgus monkey (EC50 , 21.5 nm) plasma, but not in mouse plasma. TPP2009 was also effective in partially restoring FXa activity in rabbit and cynomolgus monkey plasma treated with FVIII function-neutralizing antibodies. CONCLUSIONS: TPP2009 specifically targets a unique conformational epitope on ATß*H and blocks ATß-mediated anticoagulation. It effectively promotes coagulation in plasma, indicating the importance of ATß in hemostasis.

Mutations at positions 153 and 328 in Escherichia coli alkaline phosphatase provide insight towards the structure and function of mammalian and yeast alkaline phosphatases.

In order to understand some of the differences between human placental, human, Saccharomyces cerevisiae and Escherichia coli alkaline phosphatases in specific activity, activation by magnesium, and pH versus activity profiles, the X-ray crystal structures of three mutant E. coli alkaline phosphatases have been determined. The aligned sequences of alkaline phosphatases from mammalian, yeast and E. coli show that 25 to 30% of the amino acids are absolutely conserved and the active site residues are completely conserved with the exception of residues 153, 328 and 155. The bacterial enzyme has a salt-bridge, Asp153/Lys328, near the third metal binding site which, based on sequence homology, is apparently absent in the yeast and mammalian enzymes. The human enzymes have histidine at positions 153 and 328, and the yeast enzyme has histidine at position 328. In the E. coli enzyme, Asp153 was replaced by histidine (D153H), Lys328 was replaced by histidine (K328H), and a double mutant (DM) was constructed containing both mutations. The structure of the K328H enzyme was refined using cross-validation to a resolution of 2.3 A with a working R-factor of 0.181 and a free R-factor of 0.249. The DM structure was determined to a resolution of 2.5 A with a working R-factor of 0.166 and a free R-factor of 0.233. The structure of the D135H enzyme, which has been reported to a resolution of 2.4 A, has been re-refined using cross-validation to a working R-factor of 0.179 and a free R-factor of 0.239 for controlled comparisons with the two new structures. In all three structures the most significant changes are related to the bound phosphate inhibitor and the identity of the metal ion in the third binding site. The changes in the position of the phosphate group and the alterations at the third metal binding site indicate the structural basis for the variations in the steady-state kinetic parameters previously reported for these enzymes.

Characterization of heterodimeric alkaline phosphatases from Escherichia coli: an investigation of intragenic complementation.

Escherichia coli alkaline phosphatase (EC 3.1.3.1) belongs to a rare group of enzymes that exhibit intragenic complementation. When certain mutant versions of alkaline phosphatase are combined, the resulting heterodimeric enzymes exhibit a higher level of activity than would be expected based upon the relative activities of the parental enzymes. Nine previously identified alkaline phosphatase complementation mutants were re-examined in this work in order to determine a molecular explanation of intragenic complementation in this experimental system. The locations of these mutations were determined by DNA sequence analysis after PCR amplification of the phosphatase-negative phoA gene. Most of the mutations involved ligands to metal-binding sites. Each of the mutant enzymes was re-created by site-specific mutagenesis, expressed, purified, and kinetically characterized. To investigate cooperativity between the two subunits, we analyzed heterodimeric forms of some of the site-specific mutant enzymes. To enable the isolation of the heterodimeric alkaline phosphatase in pure form, the overall charge of one subunit was altered by replacing the C-terminal Lys residue with three Asp residues. This modification had no effect on the kinetic properties of the enzyme. Heterodimeric alkaline phosphatases were created using two methods: (1) in vitro formation by dissociation at acid pH followed by reassociation at slightly alkaline pH conditions in the presence of zinc and magnesium ions; and (2) in vivo expression from a plasmid carrying two different phoA genes. Increases in k(cat), as well as a large reduction in the p-nitrophenyl phosphate K(m) were observed for certain combinations of mutant enzymes. These results suggest that the structural assembly of E. coli alkaline phosphatase into the dimer induces cooperative interactions between the monomers necessary for the formation of the functional form of the holoenzyme.

Kinetic and structural consequences of replacing the aspartate bridge by asparagine in the catalytic metal triad of Escherichia coli alkaline phosphatase.

In each subunit of the homodimeric enzyme Escherichia coli alkaline phosphatase, two of the three metal cofactors Zn2+ and Mg2+, are bound by an aspartate side-chain at position 51. Using site-specific mutagenesis, Asp51 was mutated both to alanine and to asparagine to produce the D51A and D51N enzymes, respectively. Over the range of pH values examined, the D51A enzyme did not catalyze phosphate ester hydrolysis above non-enzymic levels and was not activated by the addition of millimolar excess Zn2+ or Mg2+. Replacement of Asp51 by asparagine, however, resulted in a mutant enzyme with reduced activity and a higher pH optimum, compared with the wild-type enzyme. At pH 8.0 the D51N enzyme showed about 1% of the activity of the wild-type enzyme, and as the pH was raised to 9.2, the activity of the D51N enzyme increased to about 10% of the value for the wild-type enzyme. Upon the addition of excess Mg2+ at pH 9.2, the D51N enzyme was activated in a time-dependent fashion to nearly the same level as the wild-type enzyme. The affinity for phosphate of the D51N enzyme decreased tenfold as the concentration of Mg2+ increased. Under optimal conditions, the k(cat)/K(m) ratio for the D51N enzyme indicated that it was 87% as efficient as the wild-type enzyme. To investigate the molecular basis for the observed kinetic differences, X-ray data were collected for the D51N enzyme to 2.3 angstroms resolution at pH 7.5, and then to 2.1 angstroms resolution at pH 9.2 with 20 mM MgCl2. The two structures were then refined. The low magnesium, low pH D51N structure showed that the third metal site was unoccupied, apparently blocked by the amide group of Asn51. At this pH the phosphate anion was bound via one oxygen atom, between the zinc cations at the first and second metal sites, which strongly resembled the arrangement previously determined for the D153H enzyme at pH 7.5. In the high magnesium, high pH D51N structure, the third metal site was also vacant, but the phosphate anion bound closer to the surface of the enzyme, coordinated to the first metal site alone. Electron density difference maps provide evidence that magnesium activates the D51N enzyme by replacing zinc at the second metal site.

Lipitoids--novel cationic lipids for cellular delivery of plasmid DNA in vitro.

BACKGROUND: Although synthetic nonviral vectors hold promise for the delivery of plasmid DNA, their gene-transfer efficiencies are far from matching those of viruses. To systematically investigate the structure-activity relationship of cationic lipids, a small library of cationic lipid-peptoid conjugates (lipitoids) was synthesized. The compounds were evaluated for their ability to form complexes with plasmid DNA and to mediate DNA transfer in vitro. RESULTS: Lipid-peptoid conjugates were conveniently prepared in high yield using solid-phase synthesis. Several lipitoids condensed plasmid DNA into 100 nm spherical particles and protected the DNA and DNase digestion. A subset of lipitoids with a repeated (aminoethyl, neutral, neutral) sidechain trimer motif conjugated with dimyristoyl phosphatidyl-ethanolamine (DMPE) mediated DNA transfer with high efficiency. CONCLUSIONS: Automated solid-phase synthesis of cationic lipids allowed the rapid synthesis of a diverse set of transfection reagents. The most active compound DMPE-(Nae-Nmpe-Nmpe)3 (Nae, N-aminoethyl glycine; Nmpe, N-p-methoxyphenethyl-glycine) is more efficient than lipofectin or DMRIE-C (two commercial cationic lipid transfection reagents) and is active in the presence and absence of serum. The activity in the presence of serum suggests potential for applications in vivo.

Hypothyroxinemia in cardiac arrest.

Thyroid function was evaluated in cardiac arrest (CA), a condition associated with marked activation of the pituitary-adrenal axis. Blood samples were obtained in 24 patients immediately after diagnosis of CA and again ten minutes later. Samples were also obtained from 22 patients admitted consecutively to the intensive care unit (ICU). Abnormalities of thyroid indexes among patients on the ICU who had not experienced CA were low triiodothyronine (T3) in 45%, low thyroxine (T4) in 32%, low free T4 (equilibrium dialysis) in 21%, and elevated reverse T3 levels in 36%. The alterations of thyroid values were both more common and marked in patients with CA, with abnormally low T3 in 84% of the patients, low T4 in 65%, low free T4 in 65%, and high reverse T3 in 80%. Thyroxine-binding globulin and prealbumin concentrations were below the normal range in 40% and 21% of patients with CA. A thyroid hormone-binding inhibitor was detected in 38% of patients with CA. Thyroglobulin level was slightly high in patients with CA but not significantly different from controls on the ICU. The abnormalities present at zero minutes were further exaggerated ten minutes after CA. We conclude that abnormalities on tests measuring thyroid function are extremely common during the cardiovascular emergency of CA.

Intraperitoneal injection of genetically modified, human mesothelial cells for systemic gene therapy.

An ideal cell type for ex vivo gene therapy should be easy to biopsy, propagate, and genetically engineer in culture, should be transplantable using simple procedures, and should express therapeutic proteins at useful levels. The mesothelial cell appears to satisfy these criteria. Several thousand proliferative mesothelial cells were present in typical specimens of nonpathologic human peritoneal fluid obtained by needle aspiration. These divided rapidly in a specialized medium to yield pure cultures of approximately 10(7) cells within 2 weeks. The replicative lifespan of mesothelial cells cultured from adults was approximately 42-52 population doublings, permitting expansion and cryopreservation of a lifetime supply of autologous cells from one fluid sample. Cells transduced with a human growth hormone (hGH) adenoviral vector secreted 100-300 microg of hGH/10(6) cells per day for at least 6 weeks in culture when maintained at quiescence. Intraperitoneal injection of transduced cells into athymic mice resulted in rapid systemic delivery of hGH, with peak plasma levels of 0.1-1 microg/ml declining over 3 weeks to <1 ng/ml. Mice receiving a second injection of engineered cells displayed the same plasma hGH levels and duration as naive mice. Cells labeled with a beta-galactosidase vector were identifiable by in situ enzymatic staining as clusters attached to peritoneal surfaces at multiple sites for at least 19 days after injection. Cells serially passaged through about three-quarters of their lifespan before transduction and injection were as effective at hGH delivery as earlier-passage cells. These results indicate the clinical potential for ex vivo gene therapy using mesothelial cells.

Interleukin-1 and cutaneous inflammation: a crucial link between innate and acquired immunity.

As our primary interface with the environment, the skin is constantly subjected to injury and invasion by pathogens. The fundamental force driving the evolution of the immune system has been the need to protect the host against overwhelming infection. The ability of T and B cells to recombine antigen receptor genes during development provides an efficient, flexible, and powerful immune system with nearly unlimited specificity for antigen. The capacity to expand subsets of antigen-specific lymphocytes that become activated by environmental antigens (memory response) is termed "acquired" immunity. Immunologic memory, although a fundamental aspect of mammalian biology, is a relatively recent evolutionary event that permits organisms to live for years to decades. "Innate" immunity, mediated by genes that remain in germ line conformation and encode for proteins that recognize conserved structural patterns on microorganisms, is a much more ancient system of host defense. Defensins and other antimicrobial peptides, complement and opsonins, and endocytic receptors are all considered components of the innate immune system. None of these, however, are signal-transducing receptors. Most recently, a large family of cell surface receptors that mediate signaling through the NF-kappaB transcription factor has been identified. This family of proteins shares striking homology with plant and Drosophila genes that mediate innate immunity. In mammals, this family includes the type I interleukin-1 receptor, the interleukin-18 receptor, and a growing family of Toll-like receptors, two of which were recently identified as signal-transducing receptors for bacterial endotoxin. In this review, we discuss how interleukin-1 links the innate and acquired immune systems to provide synergistic host defense activities in skin.