In silico prediction of the interaction of legacy and novel per- and poly-fluoroalkyl substances (PFAS) with selected human transporters and of their possible accumulation in the human body.

Per- and poly-fluorinated compounds constitute a wide group of fluorocarbon chemicals with widespread industrial applications, ranging from non-stick coating in cookware to water surfactants, from fire-fighting foams to water-repellent coatings on textiles. Presently, over 12,000 PFAS are known worldwide. In recent years, extensive research has focused on investigating the biological effects of these molecules on various organisms, including humans. Here, we conducted in silico simulations to examine the potential binding of a representative selection of PFAS to various human proteins known to be involved in chemical transportation and accumulation processes. Specifically, we targeted human serum albumin (HSA), transthyretin (TTR), thyroxine binding protein (TBG), fatty acid binding proteins (FABPs), organic anion transporters (OATs), aiming to assess the potential for bioaccumulation. Molecular docking simulations were employed for this purpose, supplemented by molecular dynamics (MD) simulations to account for protein flexibility, when necessary. Our findings indicate that so-called "legacy PFAS" such as PFOA or PFOS exhibit a higher propensity for interaction with the analysed human protein targets compared to newly formulated PFAS, characterised by higher branching and hydrophilicity, and possibly a higher accumulation in the human body.

A novel SWCNT platform bearing DOTA and ß-cyclodextrin units. "One shot" multidecoration under microwave irradiation.

The functionalization of single-walled carbon nanotubes (SWCNTs) via microwave-assisted grafting reactions enables efficient multidecoration in a single step. A novel water-soluble SWCNT platform was prepared via the simple 1,3-dipolar cycloaddition of azomethine ylides under dielectric heating. Thanks to a single grafting reaction the CNT surface binds in a 1 : 1 ratio an amino acidic ß-cyclodextrin (ß-CD) derivative and the DOTAMA moiety (1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid monoamide). This novel "one shot" synthesis, compared with multistep functionalizations, preserves the SWCNT's structural integrity (TEM images). Besides thermogravimetric analyses, the determination of the amount of ß-CD and DOTA moieties grafting onto the SWCNT's surface was performed on the basis of phenolphthalein and gadolinium complexation, respectively.

Improved adhesion to mucosal cells of water-soluble chitosan tetraalkylammonium salts.

Chitosan is a natural polymer whose bioadhesive properties make it a useful material for filming over and protecting damaged or sensitive mucosae. Much effort has been expended to develop this employ, and new applications are in the offing. The aim of the present study was to optimize the synthesis under sonochemical conditions of water-soluble chitosan tetraalkylammonium salts and to assess the mucoadhesive properties of the resulting water-soluble cationic polyelectrolytes. Aqueous solutions of several tetralkylammonium chitosan derivatives, viz. N-trimethyl- (1), N-diethylmethyl- (2), N-carboxymethyl- (3) and N-[N,N-diethylaminomethyl(diethyldimethylene ammonium)(n)]methylchitosan (4) were tested along with the parent biopolymer and its citric acid salt (5), both at neutral and acidic pH. We used a published technique for evaluating in vitro bioadhesion to isolated buccal cells, a mucosal model that can predict bioadhesive behavior in vivo. Derivatives 1 and 4 gave the best results.

Cold-induced alteration in the global structure of the male sex chromosome of In1BM2(reinverted) of Drosophila melanogaster is associated with increased acetylation of histone 4 at lysine 16.

In Drosophila melanogaster, dosage compensation occurs through hypertranscription of sex-linked genes in males. The hypertranscription involves acetylation of histone 4 at lysine 16 (H4K16) on amale X-chromosome, brought about by a histone acetyltransferase encoded by the dosage compensation gene, males absent on the first (mof). We report a phenomenon in the strain In(1)B(M2)(reinverted) of D. melanogaster where the global structure of the male X-chromosome can be altered at the third instar larval stage through a 4-h cold shock at 12+/-1 degrees C. We show that the cold shock results in a transient hyperacetylation of H4K16 and an increased expression of MOF. Control proteins H4 acetylated at lysine 5, and the dosage compensation gene msl-2, do not show any change in expression after cold shock. Cytology of the male X-chromosome at different time points during cold shock and recovery, suggests that the hyperacetylation of H4 at lysine 16 causes the X-chromosome to corkscrew into itself, thereby achieving the cold-induced change in the higher order structure of the male polytene X-chromosome. Our studies suggest a role for H4K16 in maintaining the structure of the male X-chromosome in Drosophila.

Cellular labeling with Gd(III) chelates: only high thermodynamic stabilities prevent the cells acting as 'sponges' of Gd3+ ions.

MR-labeling of cells may be carried out by adding a Gd-based contrast agent to the incubation media. The amount of gadolinium internalized in HTC and C6 cells upon incubation with Gd-DTPA-BMA is circa one order of magnitude higher than those found with Gd-DTPA, Gd-DOTA and Gd-HPDO3A, respectively. The comparison of relaxometric and mass spectrometry determinations allows us to establish that only a minor fraction of intact Gd-DTPA-BMA is internalized into the cells. Moreover the binding/uptake behavior shown by Gd-DTPA-BMA resembles that found when GdCl(3) is added to the incubation medium. We suggest that the lower stability of Gd-DTPA-BMA is responsible for a shift in the dissociation equilibrium that results in the net transfer of Gd(3+) ions on the cell membrane followed by a slower internalization process. The transmetallation process is mediated by components of the incubation media, among which a dominant role is represented by phosphate anions. The uptake of Gd(3+) ions is clearly reflected in the drastic decrease of cell viability observed for cells labeled with Gd-DTPA-BMA.

Clinical evaluation of ZD6474, an orally active inhibitor of VEGF and EGF receptor signaling, in patients with solid, malignant tumors.

BACKGROUND: ZD6474 selectively inhibits the tyrosine kinase activity of vascular endothelial growth factor receptor and epidermal growth factor receptor. The safety, tolerability and pharmacokinetics of ZD6474 were assessed in a phase I dose-escalation study of patients with advanced solid tumors. PATIENTS AND METHODS: Adult patients with tumors refractory to standard treatments received once-daily oral ZD6474 (50-600 mg) in 28-day cycles, until disease progression or unacceptable toxicity was observed. RESULTS: Seventy-seven patients were treated at doses of 50 mg (n=9), 100 mg (n=19), 200 mg (n=8), 300 mg (n=25), 500 mg (n=8), and 600 mg (n=8). Adverse events were generally mild, and the most common dose-limiting toxicities (DLT) were diarrhea (n=4), hypertension (n=4), and rash (n=3). The incidence of most adverse events appeared to be dose-dependant. In the 500 mg/day cohort, 3/8 patients experienced DLT and this dose was therefore considered to exceed the maximum tolerated dose. Pharmacokinetic analysis confirmed that ZD6474 was suitable for once-daily oral dosing. CONCLUSIONS: Once-daily oral dosing of ZD6474 at 300 mg/day is generally well tolerated in patients with advanced solid tumors, and this dose is being investigated in phase II trials.

Targeting cells with MR imaging probes based on paramagnetic Gd(III) chelates.

The low sensitivity is the major disadvantage of MRI as compared to PET. Therefore, amplification strategies are necessary for specific pathway labeling. This survey is aimed at exploring different routes to the entrapment of Gd(III) chelates in various type of cells at amounts sufficiently large to allow MRI visualization. Namely, the obtained results have been summarized in terms of internalization via i) pinocytosis; ii) phagocytosis; iii) receptors; iv) receptor mediated endocytosis; v) transporters; vi) transmembrane carrier peptides. MRI visualization of cells appears possible when the number of internalized Gd(III) chelates is of the order of 10(7)-10(8)/cell. Pinocytosis shows to be particularly useful for labeling cells that can be incubated for several hours in the presence of high concentrations of Gd-agent. This approach appears very effective for labeling stem cells. Nanoparticles filled with Gd-chelates can be used for an efficient loading of cells endowed with a good phagocytic activity. Entrapment via receptors most often results in receptor mediated endocytosis. Suitably functionalized monomeric and multimeric Gd-chelates can be considered for being internalized by this route as well as supramolecular systems such as those formed between Avidin and biotinylated Gd-complexes. Exploitation of up-regulated transporters of nutrients in tumor cells appears to be a promising route for their differentiation from healthy cells. Finally, properly designed systems entering the cells by means of penetrin-like peptides deserve great attention.

[Comparison of management of advanced cancer in various organs].

The management of advanced cancer presents the greatest challenge to physicians involved in oncology. There will usually be a large burden of disease; cure is unlikely; and the needs of the patient in terms of pain control and palliation will also be important over and above the direct treatment of the disease. Different issues will arise depending on the site and pathological type of the cancer. Increasingly over the past few years, treatment protocols and guidelines have been developed for different cancers, but these can only be rough guides rather than definite treatment recommendations. Additionally in most cancers advanced disease offers the opportunity for evaluation of new treatments in Phase II studies and other trials. With the new generation of molecular targeted therapies, such as EGFR inhibitors, striking results are being seen in advanced disease that compare favourably with what has been seen previously. Other agents such as those which attack the tumour vasculature may also have promise in this setting. Palliation is also an important aspect of the management of advanced disease, and pain control in particular is an important component of patient management. In summary, the treatment of advanced disease provides a test bed for new agents, but this need to develop better cancer therapies must be balanced against patient needs for a pain-free and comfortable end to life.

Combined results from solution studies on intact influenza virus M1 protein and from a new crystal form of its N-terminal domain show that M1 is an elongated monomer.

The amino-terminal domain of influenza A virus matrix protein (residues 1-164) was crystallized at pH 7 into a new crystal form in space group P1. This packing of the protein implies that M1(1-164) was monomeric in solution when it crystallized. Otherwise, the structure of the M1 fragment in the pH 7 crystals was the same as the monomers in crystals formed at pH 4 where crystal packing resulted in dimer formation [B. Sha and M. Luo, 1997, Nature Struct. Biol. 4, 239-244]. Analysis of intact M1 protein, the N-terminal domain, and the remaining C-terminal fragment (residues 165-252) in solution also showed that the N-terminal domain was monomeric with the same dimensions as determined from the crystal structure. Intact M1 protein was also monomeric but with an elongated shape due to the presence of the C-terminal part. Circular dichroism showed that the C-terminal part of M1 contained helical structure. A model for soluble M1 is presented, based on the assumption that the C-terminal domain is spherical, in which the N- and C-terminal domains are connected by a linker sequence which is available for proteolytic attack.

Membrane interaction of influenza virus M1 protein.

The M1 protein of influenza virus is thought to make contact with the cytoplasmic tails of the glycoprotein spikes, lipid molecules in the viral membrane, and the internal ribonucleoprotein particles. Here we show electron micrographs of negatively stained virus particles in which M1 is visualized as a 60-A-long rod that touches the membrane but apparently is not membrane inserted. Photolabeling with a membrane restricted reagent resulted in labeling of the transmembrane region of haemagglutinin but not of M1, also suggesting that most of M1 is not embedded into the hydrophobic core of the viral membrane. Finally, in vitro reconstitution experiments using soluble M1 protein and synthetic liposomes or Madin-Darby canine kidney cell membranes suggest that M1 can bind to negatively charged liposomes and to the cellular membranes and that this binding can be prevented under high-salt conditions. Although none of these experiments prove that there does not exist a minor fraction of M1 that is membrane inserted, it appears that most of M1 in the virus is membrane associated through electrostatic interactions.

Syntheses and relaxation properties of mixed gadolinium hydroxypyridinonate MRI contrast agents.

The tripodal ligand tris[(3-hydroxy-1-methyl-2-oxo-1,2- didehydropyridine-4-carboxamido)ethyl]amine (TREN-Me-3,2-HOPO) forms a stable Gd3+ complex that is a promising candidate as a magnetic resonance imaging (MRI) contrast agent. However, its low water solubility prevents detailed magnetic characterization and practical applicability. Presented here are a series of novel mixed ligand systems that are based on the TREN-Me-3,2-HOPO platform. These new ligands possess two hydroxypyridinone (HOPO) chelators and one other chelator, the latter of which can be easily functionalized. The ligands described use salicylamide, 2-hydroxyisophthalamide, 2,3-dihydroxyterephthalamide, and bis(acetate) as the derivatizable chelators. The solution thermodynamics and relaxivity properties of these new systems are presented. Three of the four complexes (salicylamide-, 2-hydroxyisophthalamide-, and 2,3-dihydroxyterephthalamide-based ligands) possess sufficient thermodynamic stability for in vivo applications. The relaxivities of the three corresponding Gd3+ complexes range from 7.2 to 8.8 mM-1 s-1 at 20 MHz, 25 degrees C, and pH 8.5, significantly higher than the values for the clinically employed polyaminocarboxylate complexes (3.5-4.8 mM-1 s-1). The high relaxivities of these complexes are consistent with their faster rates of water exchange (< 100 ns), higher molecular weights (> 700), and greater numbers of inner-sphere coordinated water molecules (q = 2) relative to those of polyaminocarboxylate complexes. A mechanism for the rapid rates of water exchange is proposed involving a low energy barrier between the 8- and 9-coordinate geometries for lanthanide complexes of HOPO-based ligands. The pathway is supported by the crystal structure of La[TREN-Me-3,2-HOPO] (triclinic P1: Z = 4, a = 15.6963(2) A, b = 16.9978(1) A, c = 17.1578(2) A, alpha = 61.981(1) degrees, beta = 75.680(1) degrees, gamma = 71.600(1) degrees), which shows both 8- and 9-coordinate metal centers in the asymmetric unit, demonstrating that these structures are very close in energy. These properties make heteropodate Gd3+ complexes promising candidates for use in macromolecular contrast media, particularly at higher magnetic field strengths.

A randomized, double-blind, placebo-controlled study with pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) as an adjunct to chemotherapy for adults with de novo acute myeloid leukemia.

To determine the safety, biologic, and clinical benefits of pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF; Amgen, Thousand Oaks, CA) after myelosuppressive chemotherapy in acute myeloid leukemia (AML), 108 adult patients with de novo AML were randomized to receive either PEG-rHuMGDF (2.5 microg/kg/d or 5 microg/kg/d) for up to 21 doses (group A), a single dose of 2.5 microg/kg PEG-rHuMGDF, 7 daily doses of 2.5 microg/kg PEG-rHuMGDF (group B), or placebo. The greatest biologic activity was seen in group A with a median peak platelet count of 1,084 x 10(9)/L, occurring at a median 9 days after the last dose of study drug, compared with 517 x 10(9)/L and 390 x 10(9)/L in group B and placebo group, respectively. Thrombocytosis (platelets >1,000 x 10(9)/L) was seen at rates of 52%, 8%, and 9% in groups A, B, and placebo, respectively, but were not associated with any adverse event. There was no effect on median time to transfusion independent platelet recovery (> or = 20 x 10(9)/L). The median time to neutrophil recovery (> or = 500/microL) and red blood cell transfusion requirements were similar in all groups, and there was no apparent stimulation of leukemia. PEG-rHuMGDF was biologically active and well tolerated. Further investigation of dose and scheduling is required, specifically earlier dosing before and during chemotherapy.

Unfolding studies of human adenovirus type 2 fibre trimers. Evidence for a stable domain.

Adenovirus fibres are trimeric proteins that protrude from the 12 fivefold vertices of the virion and are the cell attachment organelle of the virus. They consist of three segments: an N-terminal tail, which is noncovalently attached to the penton base, a thin shaft carrying 15 amino acid pseudo repeats, and a C-terminal globular head (or knob) which recognizes the primary cell receptor. Due to their exceptional stability, which allows easy distinction of native trimers from unfolded forms and folding intermediates, adenovirus fibres are a very good model system for studying folding in vivo and in vitro. To understand the folding and stability of the trimeric fibres, the unfolding pathway of adenovirus 2 fibres induced by SDS and temperature has been investigated. Unfolding starts from the N-terminus and a stable intermediate accumulates that has the C-terminal head and part of the shaft structure (shown by electron microscopy). The unfolded part can be digested away using limited proteolysis, and the precise digestion sites have been determined. The remaining structured fragment is recognized by monoclonal antibodies that are specific for the trimeric globular head and therefore retains a native trimeric structure. Taken together, our results indicate that adenovirus fibres carry a stable C-terminal domain, consisting of the knob with five shaft-repeats.

Recombinant human megakaryocyte growth and development factor increases levels of circulating haemopoietic progenitor cells post chemotherapy in patients with acute myeloid leukaemia.

By participating in a randomized safety and efficacy study of pegylated-recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) post induction and consolidation chemotherapy for de novo acute myeloid leukaemia, serial determinations of circulating haemopoietic progenitor cells were performed during 18 chemotherapy courses in eight patients (three receiving placebo; one, 2.5; and four, 5.0 microg/kg/d MGDF, respectively). Whereas failure to achieve complete remission (CR) was generally associated with poor progenitor cell increments following chemotherapy, substantial progenitor cell mobilization consistently occurred during haemopoietic recovery in patients entering, or in CR, with significantly higher peak values in patients receiving 5 microg/kg/d of MGDF as compared to controls. The median increases of progenitor cell numbers by chemotherapy alone and chemotherapy plus 5.0 microg/kg/d MGDF over that in normal individuals with steady-state haemopoiesis were 10- and 45-fold for CFU-GM, 3- and 17-fold for BFU-E, and 2- and 18-fold for CFU-mix. CFU-Mk levels were not increased above normal by chemotherapy alone but were 15-fold enhanced by chemotherapy plus MGDF. Recruitment of CD34+ cells post chemotherapy was also potentiated by MGDF. Our results suggest MGDF as a potent agent to augment progenitor cell mobilization after successful induction or consolidation chemotherapy in patients with AML.

Characterization of rabies virus nucleocapsids and recombinant nucleocapsid-like structures.

Rabies virus nucleoprotein (N) was produced in insect cells using the baculovirus expression system described by Préhaud et al. (Virology 178, 486-497, 1990). The protein was either purified on a CsCl gradient, resulting in a mixture of nucleocapsid-like structures and beaded rings, as observed by electron microscopy, or on a glycerol gradient that resulted in a preparation of the rings only. The rings and nucleocapsid-like structures had the same morphological characteristics as viral nucleocapsids. N in these structures is an 84 A long and thin molecule that is spaced at around 34 A along the length of the nucleocapsid, identical in shape and spacing as the nucleoprotein in nucleocapsids of rabies virus and very similar to those of vesicular stomatitis virus. The recombinant nucleocapsids contained RNA with a stoichiometry similar to that found in viral nucleocapsids. The RNA bound in the beaded rings was a subset of the insect cellular RNA. One of the RNA species was partially sequenced and, although a positive identification could not be made, could correspond to a tRNA. With respect to sensitivity to trypsin and RNase digestion, the recombinant and viral nucleocapsids behaved similar. Trypsin cleaved a 17 kDa fragment from the carboxy terminus of N with only a very small effect on the morphology of the nucleocapsids. RNase A completely digested the resident RNA in both viral and recombinant nucleocapsids into fragments of 4-5 nt long, again with no effect on the morphology of the nucleocapsids. Thus, when the RNA is cleaved, the structure must be maintained by protein-protein contacts. Experiments to remove the resident RNA from viral and recombinant rabies virus nucleocapsids failed, whereas the same methods used to eliminate the RNA from vesicular stomatitis virus nucleocapsids was successful.

Influence of metabolic and genetic factors on tumour necrosis factor-alpha and lymphotoxin-alpha production in insulin-dependent diabetes mellitus.

The potential role of tumour necrosis factors (TNFs) in autoimmunity and insulin-dependent diabetes mellitus (IDDM) led us to determine in vitro TNF-alpha and lymphotoxin-alpha (LT-alpha, TNF-beta) production in IDDM patients according to TNF polymorphism. LT-alpha production of peripheral blood mononuclear cells (PBMC) was lower in diabetic subjects (m = 0.30 +/- 0.2 ng.10(-6) cells) than controls (m = 0.68 +/- 0.3 ng.10(-6) cells, p < 0.05), and early age-at-onset was correlated with low LT-alpha production (rs = 0.8, p = 0.0006). TNF-alpha production was the same in patients and controls, but patients with HbA1c > or = 8% had a higher TNF-alpha production (m = 3.05 +/- 1.2 ng.10(-6) cells) than those with HbA1c < 8% (m = 1.31 +/- 0.33 ng.10(-6) cells, p < 0.05). A study of the microsatellite TNFa region close to the LTA gene showed that the presence of the TNFa1 allele in HLA-(DR3) subjects was associated with increased risk of IDDM. TNFa1-positive subjects (both patients and controls) also had lower LT-alpha production than other subjects. These results indicate that low LT-alpha production is an additional risk factor for IDDM and that poor glycaemic control in patients is associated with enhanced PBMC TNF-alpha production which causes an imbalance between TNF-alpha and LT-alpha production in IDDM patient.

Conformational flexibility and polymerization of vesicular stomatitis virus matrix protein.

The matrix protein of vesicular stomatitis virus (VSV) plays a pivotal role in viral assembly. We previously demonstrated the ability of M protein to self-associate at low salt concentrations. Now, we show the ability of M protein to polymerize in the presence of ZnCl2 in a nucleation-dependent manner. Analysis of kinetics revealed that the nuclei are probably made of three or four molecules of M. These results are consistent with the idea that in vitro self association of M protein is not due to amorphous aggregation but rather reflects an intrinsic ability of M to polymerize. Using attenuated total reflectance Fourier transform infrared spectroscopy, we showed that M polymerization is associated with an increase in the beta-sheet content of the protein. We propose a model explaining both the apparent M protein solubility in infected cells and how M polymerization could promote viral assembly. Data available for other negative strand viruses suggest that M polymerization may be the general basis of viral assembly.

A randomized, double-blind, placebo-controlled, phase III study of filgrastim in remission induction and consolidation therapy for adults with de novo acute myeloid leukemia. The International Acute Myeloid Leukemia Study Group.

The safety and efficacy of filgrastim as an adjunct to acute myeloid leukemia (AML) induction and consolidation therapy was assessed in this prospective double-blind, randomized, placebo-controlled, multicenter trial. A total of 521 consecutive de novo AML patients aged 16 or more years were randomized to receive filgrastim (5 microg/kg/d subcutaneously) or placebo after standard induction as well as consolidation chemotherapy. Blinded study drug was given from 24 hours after chemotherapy until the absolute neutrophil count was >/=1.0 x 10(9)/L for 3 consecutive days. The overall complete remission rate was 68%. After a median follow-up of 24 months (range 5 to 40) the median disease-free survival was 10 months (95% confidence interval [CI], 8.7 to 10.8) and the median overall survival was 13 months (95%CI, 12.2 to 14.6). These did not differ between treatment groups. Patients receiving filgrastim experienced neutrophil recovery 5 days earlier after induction 1 than those receiving placebo (P < .0001). This was accompanied by reductions in the duration of fever (7 v 8.5 days; P = .009), parenteral antibiotic use (15 v 18.5 days; P = .0001), and hospitalization (20 v 25 days; P = .0001). Similar reductions were seen after induction 2 and the consolidation courses. There was a significant reduction in the number of patients requiring systemic antifungal therapy in the filgrastim group during induction treatment (34% v 43%; P = .04). In conclusion, filgrastim is safe in that it had no negative impact on the prognosis of the AML patients. In addition, it effectively reduced the duration of neutropenia, leading to significant clinical benefits by reducing the duration of fever; requirement for parenteral anti-infectives, specifically amphotericin B; and the duration of hospitalization.