Developing Integrated Approaches for Testing and Assessment (IATAs) in order to support nanomaterial safety

Due to the unique characteristics of nanomaterials (NM) there has been an increase in their use in nanomedicines and innovative medical devices (MD). Although large numbers of NMs have now been developed, comprehensive safety investigations are still lacking. Current gaps in understanding the potential mechanisms of NM-induced toxicity can make it challenging to determine the safety testing necessary to support inclusion of NMs in MD applications. This article provides guidance for implementation of pre-clinical tailored safety assessment strategies with the aim to increase the translation of NMs from bench development to clinical use. Integrated Approaches to Testing and Assessment (IATAs) are a key tool in developing these strategies. IATAs follow an iterative approach to answer a defined question in a specific regulatory context to guide the gathering of relevant information for safety assessment, including existing experimental data, integrated with in silico model predictions where available and appropriate, and/or experimental procedures and protocols for generating new data to fill gaps. This allows NM developers to work toward current guidelines and regulations, while taking NM specific considerations into account. Here, an example IATA for NMs with potential for direct blood contact was developed for the assessment of haemocompatibility. This example IATA brings together the current guidelines for NM safety assessment within a framework that can be used to guide information and data gathering for the safety assessment of intravenously injected NMs. Additionally, the decision framework underpinning this IATA has the potential to be adapted to other testing needs and regulatory contexts.

The human neurokinin B gene, TAC3, and its promoter are regulated by Neuron Restrictive Silencing Factor (NRSF) transcription factor family

We have previously shown that one of the major determinants directing the expression of the preprotachykinin-A (TAC1) gene, which encodes the neuropeptide substance P, is the transcription factor Neuronal Restrictive Silencer Factor (NSRF), which is also termed Repressor Element-1 Silencing Factor (REST). In rodent models of epilepsy, NRSF and its truncated isoform short NRSF (sNRSF), also termed REST4, are increased as an immediate response to seizure. In similar models the neurokinin B (NKB) gene (TAC3) is also induced and NKB has also been shown to be proconvulsant. In this communication we have demonstrated that both the TAC3 endogenous gene and its promoter are regulated, directly or indirectly, by the NRSF transcription factors resulting in both the increased expression of the endogenous gene and increased reporter gene activity. We demonstrate by chromatin immunoprecipitation analysis that NRSF and sNRSF will bind to the NKB promoter in vivo. Consistent with a model in which NRSF modulation of TAC3 gene expression is a mechanism that operates during epilepsy, the observed increases in both the level of the endogenous gene and the activity of the NKB promoter by these NRSF variants, were diminished by the action of the anticonvulsant drug, carbamazepine.

Endostatin therapy reveals a U-shaped curve for antitumor activity

Developing continuous systemic delivery of endostatin has been a goal of many laboratories. We have employed a method of gene therapy utilizing different viral constructs. Here, we report that a new serotype of adeno-associated viruses, which incorporates canine endostatin, provides dose-dependent transgene expression in the circulation after intramuscular injection in mice. Elevated levels of endostatin remained stable in the circulation for at least 4 months. In vitro assays determined that the protein expressed was biologically active. Antitumor activities of the above construct demonstrated a U-shape curve, where the maximum activity was observed within a certain critical concentration range. These data suggest that an optimum dose range may be required to achieve therapeutic efficacy in large animal models.

Implications of a genomic search for autophagy-related genes in trypanosomatids

Autophagy is the process by which cellular components are directed to and degraded in the vacuole or lysosome and has been studied largely in yeasts. We present here an in silico genomic analysis of trypanosomatid autophagy aimed at highlighting similarities and differences with autophagy in other organisms. Less than half of the yeast autophagy-related proteins examined have certain putative orthologues in trypanosomatids. A cytosol-to-vacuole transport system is clearly lacking in these organisms. Other absences are even more unexpected and have implications for our understanding of the molecular mechanisms of autophagy. The results are consistent with taxon-specific addition of components to a core autophagy machinery during evolution.

Intracellular pH, intrauterine growth and the insulin resistance syndrome

Defects of both sodium-hydrogen exchange (NHE) and sodium-lithium countertransport (SLC) have been described in subjects at increased risk of coronary heart disease (CHD). Sodium transport is linked to the regulation of cell volume, intracellular pH and cell growth, which may explain aspects of this association. However, impaired growth in early life is also linked to adult CHD, and 'programmed' alterations of cell behaviour are postulated to be responsible for this. In this study, therefore, we examined whether NHE or SLC in adults are predicted by anthropometric measures at birth, as well as being associated with insulin resistance syndrome (IRS) variables in adulthood. Red cell SLC was measured in 26 adults, and NHE in dermal fibroblasts from another 15 subjects characterized anthropometrically at birth. SLC activity correlated with LDL cholesterol, triglycerides and urate (r=0.42 - 0.49; 0.05 > P>0.01), but not birth anthropometry. NHE V(max) correlated with plasma insulin (r=0.80; P<0.001), but birth weight was unrelated to V(max), K(m) or Hill coefficient for H(i)(+). However, pH(i) correlated with birth weight (r=0.74; P=0.002), insulin sensitivity (r=0.52; P<0.05), fasting glucose (r=-0.52; P<0.05) 2 h insulin (r=0.51; P<0.05) 2 h glucose (r=-0.54; P<0.05). In conclusion, red cell SLC is related to IRS variables, but not with birth weight measures. In contrast, low intracellular pH(i) is related to both low birth weight and adult insulin resistance, suggesting it might be a 'programmed' cell phenotype, although this is not apparently explained by altered NHE kinetics.

Oligomerization-dependent regulation of motility and morphogenesis by the collagen XVIII NC1/endostatin domain

Collagen XVIII (c18) is a triple helical endothelial/epithelial basement membrane protein whose noncollagenous (NC)1 region trimerizes a COOH-terminal endostatin (ES) domain conserved in vertebrates, Caenorhabditis elegans and Drosophila. Here, the c18 NC1 domain functioned as a motility-inducing factor regulating the extracellular matrix (ECM)-dependent morphogenesis of endothelial and other cell types. This motogenic activity required ES domain oligomerization, was dependent on rac, cdc42, and mitogen-activated protein kinase, and exhibited functional distinction from the archetypal motogenic scatter factors hepatocyte growth factor and macrophage stimulatory protein. The motility-inducing and mitogen-activated protein kinase-stimulating activities of c18 NC1 were blocked by its physiologic cleavage product ES monomer, consistent with a proteolysis-dependent negative feedback mechanism. These data indicate that the collagen XVIII NC1 region encodes a motogen strictly requiring ES domain oligomerization and suggest a previously unsuspected mechanism for ECM regulation of motility and morphogenesis.

Low dependency residents in private nursing homes in Glasgow

OBJECTIVES

To investigate why nursing home care had been recommended for elderly people who were assessed subsequently as being of low dependency.

DESIGN

Examination of community care assessment documentation for low dependency residents to assess reasons for recommending nursing home care; comparison of these with data from a subsequent SCRUGs (Scottish Care Resource Utilisation Groups) assessment.

SETTING AND SUBJECTS

Three hundred and four residents within eight private nursing homes in Glasgow.

RESULTS

Twenty six percent of the residents were described as being of low dependency. Of these, 44% had dementia and 6% personal care needs alone; 29% had medical problems which required nursing input, but not necessarily to a level requiring nursing home care. Information in the community care assessment often described a higher level of need than that identified subsequently. From the information given in the medical component of the community care assessment it was often unclear why the decision to recommend nursing home care was made.

CONCLUSION

Admission to nursing homes may be encouraged by over-emphasiZing care requirements, by placing emphasis on safety rather than independence and by inadequate recording of information. Elderly people who cannot remain at home need improved assessment procedures, better understanding of their needs and a wider range of accommodation options.

Liquid chromatographic determination of FP-21399 in plasma of patients with HIV infection

A high-performance liquid chromatographic (HPLC) analysis method for the novel anti-HIV drug FP-21399 in human plasma was developed. The method employed the combination of organic solvent extraction and solid phase extraction. Analysis of FP 21399 and two major metabolites was achieved within 18 min using a reverse phase Puresil Cl 8 analytical column (4.6 x 150 mm, 5 microm, Waters) with a mobile phase of water-acetonitrile containing 20 mM triethylamine acetate (apparent pH 7.0). Linear gradient of mobile phase was applied as water-acetonitrile from 78:22 (v/v) to 55:45 over 8 min, and held at this ratio for the next 4 min. An ultraviolet-visible detector was operated at 265 mn from 0 to 8 min and at 600 mn from 8 min and after. The retention time of FP-21399 was 8.8 min and a linear response was observed over the concentration range 0.01 100 microg ml(-1) (r = 0.994). Lower limit of quantitation was found to be 0.01 microg ml(-1). Intra- and inter-assay precision varied in the range of 0.2 to 8% and 1-12%, respectively. The bias ranged from -17-3% for all analyses. A series of clinical plasma specimens were successfully analyzed using this method. The strategies for the method optimization on HIPLC separation and extraction procedure are discussed as well.

The spectrum of patched mutations in a collection of Australian basal cell carcinomas

Inactivating mutations in the human patched (PTCH) gene have been identified in both familial and sporadic basal cell carcinomas (BCCs). In some tumors mutations have been detected in both alleles thereby supporting the role of PTCH as a tumor suppressor gene. We have analyzed 22/23 coding exons of PTCH for mutations in 44 sporadic BCCs, and detected 10 novel mutations in nine tumors. In two of the mutant tumors the remaining allele was inactivated by loss of heterozygosity. Five novel PTCH polymorphisms were also identified. Most of the variations found were C>T substitutions at dipyrimidine sites, supporting previous studies which indicate a role for ultraviolet-B in the genesis of sporadic BCCs.

The bis-azo compound FP-21399 inhibits HIV-1 replication by preventing viral entry

The bis-azo compound FP-21399 inhibits HIV-1 infection. We now show that FP-21399 acts on the HIV-1 envelope glycoprotein to prevent viral replication. This compound targets the entry step of the HIV-1 replication cycle as demonstrated by time-of-addition and single cycle viral entry assays. The entry of SIVmac239, which uses the same coreceptors (CD4/CCR5) as HIV-1, was not inhibited by FP-21399, indicating that the antiviral effect of FP-21399 is specific for the HIV-1 envelope glycoprotein and is not dependent upon the cellular receptors CD4 and CCR5. FP-21399 inhibits neither the activity of HIV-1 reverse transcriptase nor the expression of HIV-1 early mRNA. Finally, this compound inhibits gp120 shedding of the T-tropic virus. Our results suggest that the anti-HIV activity of FP-21399 is due to its interaction with HIV-1 gp120/41 complex during viral entry.

De novo mutations of the Patched gene in nevoid basal cell carcinoma syndrome help to define the clinical phenotype

The demonstration that mutations in the Patched (PTCH) gene cause nevoid basal cell carcinoma syndrome (NBCCS) has led to the identification of the exact molecular lesion in a percentage of individuals with the syndrome. In addition, it has been possible to determine, through molecular analysis of parents and other relatives of these individuals, if the mutation is inherited or has arisen de novo. We have previously reported 28 mutations in individuals with NBCCS, and here we present an additional 4 novel mutations. We have also analyzed relatives of a number of the individuals in whom we have found mutations. In total we have identified 8 individuals who carry a de novo mutation in the PTCH gene. In 5 of these cases, clinical and radiological examination had not unequivocally ruled out a diagnosis in one of the parents. This helps to define the clinical phenotype and suggests that diagnostic criteria in this complex syndrome may require review.

FP-21399 blocks HIV envelope protein-mediated membrane fusion and concentrates in lymph nodes

The identification of fusin and other chemokine receptors as coreceptors for HIV-1 has renewed the interest in agents that may prevent viral entry. Polyanionic compounds such as dextran sulfate, curdian sulfate, and suramin act on the V3 loop of the viral envelope and may prevent its interaction with fusin. These agents show activity against a wide range of HIV-1 strains, but have undesirable circulating half-life, bioavailability, and toxicity. We have developed a small molecule inhibitor of HIV-1 that has several advantages over these other agents. FP-21399 is a novel compound of the bis(disulfonaphthalene) dimethoxybenzene class that blocks entry of HIV into CD4+ cells and blocks fusion of infected and noninfected CD4+ cells. This compound only weakly inhibits binding of CD4 and gp120, at concentrations much greater than are required to block viral entry. Furthermore, FP-21399 can block the interaction between gp120 and antibodies directed against the V3 loop, but does not block binding of antibodies directed against the V4 loop. Animal studies demonstrate that FP-21399 is concentrated in lymph nodes, making it a promising compound for anti-HIV therapy. In SCID mice reconstituted with human immune cells, maintenance of HIV-1 infection was blocked by a 5-day treatment with low doses of FP-21399, suggesting that lymph node accumulation may contribute to antiviral activity. Finally, attempts to generate drug-resistant virus in cell culture resulted in only weakly resistant variants with IC90 values that are much lower than concentrations of FP-21399 found in lymph nodes.

Most germ-line mutations in the nevoid basal cell carcinoma syndrome lead to a premature termination of the PATCHED protein, and no genotype-phenotype correlations are evident

The human homologue of the Drosophila segment polarity gene patched is implicated in the development of nevoid basal cell carcinoma syndrome (NBCCS) and in the genesis of sporadic basal cell carcinomas. In order to examine the phenotypic variability in NBCCS and to highlight functionally important domains of the PTCH protein, we have now screened 71 unrelated NBCCS individuals for mutations in the PTCH exons. We identified 28 mutations that are distributed throughout the entire gene, and most (86%) cause protein truncation. As part of this analysis, we demonstrate that failure of one NBCCS family to show clear linkage to chromosome 9q22.3-31 is most likely due to germinal mosaicism. We have identified three families bearing identical mutations with variable phenotypes, suggesting phenotypic variability in NBCCS is a complex genetic event. No phenotype genotype correlation between the position of truncation mutations and major clinical features was evident. Two missense mutations have been identified, and their location within transmembrane domains supports the notion that PTCH may have a transport function. The preponderance of truncation mutants in the germ line of NBCCS patients suggests that the developmental defects associated with the disorder are most likely due to haploinsufficiency.

Mutations of the human homolog of Drosophila patched in the nevoid basal cell carcinoma syndrome

The nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant disorder characterized by multiple basal cell carcinomas (BCCs), pits of the palms and soles, jaw keratocysts, a variety of other tumors, and developmental abnormalities. NBCCS maps to chromosome 9q22.3. Familial and sporadic BCCs display loss of heterozygosity in this region, consistent with the gene being a tumor suppressor. A human sequence (PTC) with strong homology to the Drosophila segment polarity gene, patched, was isolated from a YAC and cosmid contig of the NBCCS region. Mutation analysis revealed alterations of PTC in NBCCS patients and in related tumors. We propose that a reduction in expression of the patched gene can lead to the developmental abnormalities observed in the syndrome and that complete loss of patched function contributes to transformation of certain cell types.

Association of proinsulin-like molecules with lipids and fibrinogen in non-diabetic subjects--evidence against a modulating role for insulin

Elevated concentrations of proinsulin-like molecules, other than insulin, may be associated with abnormalities of cardiovascular risk factors, promoting atherogenesis and thrombosis. Using specific assays we examined the relationship of levels of insulin, intact proinsulin and des-31,32 proinsulin to blood pressure, lipids, fibrinogen, factor VII and albumin excretion rate in 270 europids with normal glucose tolerance. After correcting for age and body mass index, fasting and 2-h insulin concentrations were significantly associated with those of total and LDL-cholesterol (r = 0.18-0.22), HDL-cholesterol (both r = -0.20) and triglycerides (r = 0.21 and 0.18), but not with blood pressure. Concentrations of intact and des-31,32 proinsulin showed significant associations with those of total and LDL-cholesterol (r = 0.20-0.23), HDL-cholesterol (r = -0.31 and -0.32) and triglycerides (r = 0.22 and 0.26). Fasting insulin and intact proinsulin concentrations were significantly associated with fibrinogen (r = -0.15 and 0.18). Concentrations of proinsulin-like molecules comprised less than 10% of all insulin-like molecules, and so were calculated not to influence previously described relationships between insulin concentrations and cardiovascular risk factors measured using non-specific assays. In multiple regression analyses des-31,32 proinsulin concentration was more strongly associated with those of HDL-cholesterol (negatively), LDL-cholesterol and triglycerides than fasting insulin concentrations, while intact proinsulin replaced insulin concentrations in their relationships with fibrinogen. Our results show correlations between dyslipidaemia and proinsulin-like molecules at concentrations at which biological, insulin-like, activity appears unlikely. We also show relationships between LDL-cholesterol and fibrinogen and the proinsulin-like molecules.(ABSTRACT TRUNCATED AT 250 WORDS)

Protein synthesis in lysates of Aedes albopictus cells infected with vesicular stomatitis virus

Aedes albopictus cells (clone LT-C7) showed a marked cytopathic effect and inhibition of protein synthesis (both host and viral) after infection with vesicular stomatitis virus (VSV), but only if (i) cultures were incubated at 34 degrees C rather than 28 degrees C and (ii) serum was present in the medium (S. Gillies and V. Stollar, Mol. Cell. Biol. 2:66-75, 1982). To learn more about how protein synthesis is shut off in VSV-infected A. albopictus cells, we have compared cell-free protein synthesis in extracts prepared from VSV-infected cells and control cells. Extracts prepared 6 h after infection from VSV-infected cells maintained at 34 degrees C in the presence of serum reflected what was observed with intact cells in at least two respects: (i) they showed a markedly diminished capacity to carry out protein synthesis (whether directed by endogenous or exogenously added mRNA), and (ii) there was decreased phosphorylation in vitro by [gamma-32P]ATP of a specific ribosomal protein (Gillies and Stollar, Mol. Cell. Biol. 2:66-75, 1982). In addition, and consistent with a block at the level of initiation, the formation of 80S initiation complexes, as measured by binding of VSV 12 to 18S mRNA, was reduced in the inactive extracts. Addition of an S-100 fraction from uninfected cells to the inactive extract reversed each of the aforementioned changes; i.e., it restored protein synthetic activity, it stimulated the formation of 80S initiation complexes, and it increased phosphorylation of the specific ribosomal protein referred to above. The active component in the S-100 fraction was heat labile and non-dialyzable and, upon ammonium sulfate fractionation of the S-100 fraction, was found in the 40 to 70% saturation fraction. Our findings suggest that VSV infection of A. albopictus cells inhibits protein synthesis by inactivating a macromolecular component, probably a protein, in the S-100 fraction which may be involved in the initiation of protein synthesis. More specifically, we suggest that this component is involved in the joining of the ribosomal subunits to form 80S initiation complexes.

Conditions necessary for inhibition of protein synthesis and production of cytopathic effect in Aedes albopictus cells infected with vesicular stomatitis virus

The relationship between the development of cytopathic effect (CPE) and the inhibition of host macromolecular synthesis was examined in a CPE-susceptible cloned line of Aedes albopictus cells after infection with vesicular stomatitis virus. To induce rapid and maximal CPE, two conditions were required: (i) presence of serum in the medium and (ii) incubation at 34 degrees C rather than at 28 degrees C. In the absence of serum, incubation of infected cultures at 34 degrees C resulted in a significant increase in viral protein and RNA synthesis compared with that observed at 28 degrees C. However, when serum was present in the medium, by 6 h after infection protein synthesis (both host and viral) was markedly inhibited when infected cells were maintained at 34 degrees C. RNA synthesis (host and viral) was also inhibited in vesicular stomatitis virus-infected cells maintained at 34 degrees C with serum, but somewhat more slowly than protein synthesis. Examination of polysome patterns indicated that when infected cultures were maintained under conditions which predispose to CPE, more than half of the ribosomes existed as monosomes, suggesting that protein synthesis was being inhibited at the level of initiation. In addition, the phosphorylation of one (or two) polysome-associated proteins was reduced when protein synthesis was inhibited. Our findings indicate a strong correlation between virus-induced CPE in the LT-C7 clone of A. albopictus cells and the inhibition of protein synthesis. Although the mechanism of the serum effect is not understood, incubation at 34 degrees C probably predisposes to CPE and inhibition of protein synthesis by increasing the amount of viral gene products made.

Translation of vesicular stomatitis and Sindbis virus mRNAs in cell-free extracts of Aedes albopictus cells

We have developed a cell-free system from Aedes albopictus (mosquito) cells which is able to carry out endogenous protein synthesis and is stable to freezing and thawing. Successful preparation of extracts was found to depend on the presence of purified placental RNase inhibitor during cell breakage. Micrococcal nuclease-treated extracts translated exogenously added Sindbis 26S or vesicular stomatitis virus mRNA with a high degree of fidelity, demonstrating that initiation of protein synthesis had occurred. Evidence is presented showing that when cell fractions containing intracellular membranes were used to translate vesicular stomatitis virus mRNA, the G protein was glycosylated and inserted into microsomal vesicles. Additional studies indicate that initiation of protein synthesis in this system is dependent on a capped and methylated 5'-terminal structure in the mRNA.

Viral RNA polymerases: electron microscopy of reovirus reaction cores

The Kleinschmidt technique has been used to observe reovirus cores that have synthesized messenger RNA. Some individual viral cores probably synthesize all ten messenger RNA molecules in vitro. Each messenger RNA molecule appears to be attached to a different site on the core surface, implying that there are probably a number of different enzymic sites in each core.