Evaluation of PEG-coated iron oxide nanoparticles as blood pool tracers for preclinical magnetic particle imaging.

Superparamagnetic iron oxide (SPIO) nanoparticles with optimized and well-characterized properties are critical for Magnetic Particle Imaging (MPI). MPI is a novel in vivo imaging modality that promises to integrate the speed of X-ray CT, safety of MRI and sensitivity of PET. Since SPIOs are the source of MPI signal, both the core and surface properties must be optimized to enable efficient in vivo imaging with pharmacokinetics tailored for specific imaging applications. Existing SPIOs like Resovist (ferucarbotran) provide a suboptimal MPI signal, and further limit MPI's in vivo utility due to rapid systemic clearance. An SPIO agent with a long blood half-life (t1/2) would be a versatile MPI tracer with widespread applications. Here we show that a long circulating polyethylene glycol (PEG)-coated SPIO tracer, LS-008, provides excellent colloidal stability and a persistent intravascular MPI signal, showing its potential as the first blood pool tracer optimized for MPI. We evaluated variations of PEG coating and found that colloidal stability of tracers improved with the increasing PEG molecular weight (keeping PEG loading constant). Blood circulation in mice, evaluated using Magnetic Particle Spectrometry (MPS), showed that the t1/2 of SPIO tracers varied with both PEG molecular weight and loading. LS-008, coated with 20 kDa PEG at 18.8% loading capacity, provided the most promising long-term colloidal stability with a t1/2 of about 105 minutes in mice. In vivo MPI imaging with LS-008 using a 7 T/m/µ0 3D x-space MPI mouse scanner revealed a prolonged intravascular signal (3-5 hours) post-injection. Our results show the optimized magnetic properties and long systemic retention of LS-008 making it a promising blood pool MPI tracer, with potential to enable MPI imaging in cardio- and cerebrovascular disease models, and solid tumor quantification and imaging via enhanced permeation and retention.

Quantitative trait loci for resistance to Heligmosomoides bakeri and associated immunological and pathological traits in mice: comparison of loci on chromosomes 5, 8 and 11 in F2 and F6/7 inter-cross lines of mice.

A comparison of F2 and F6/7 inter-cross lines of mice, derived from CBA and SWR parental strains, has provided strong evidence for several previously undetected quantitative trait loci (QTL) for resistance to Heligmosomoides bakeri. Five QTL affecting average faecal egg counts and/or worm burdens in week 6 were detected on mouse chromosomes 5 (Hbnr9 and Hbnr10), 8 (Hbnr11) and 11 (Hbnr13 and Hbnr14). Three QTL for faecal egg counts in weeks 4 and 6 were found on both chromosomes 5 (Hbnr9) and 11 (Hbnr13 and Hbnr14). Two QTL for the mucosal mast cell protease 1 (MCPT1) response were located on chromosomes 8 (Hbnr11) and 11 (Hbnr13), two for the IgG1 antibody response to adult worms on chromosomes 5 (Hbnr10) and 8 (Hbnr11), two for PCV in week 6 on chromosomes 5 (Hbnr9) and 11 (Hbnr13), and two for the granulomatous response on chromosome 8 (Hbnr12) and 11 (Hbnr15). Our data emphasize that the control of resistance to H. bakeri is multigenic, and regulated by genes within QTL regions that have a complex range of hierarchical relationships.

Effects of airborne World Trade Center dust on cytokine release by primary human lung cells in vitro.

There are continuing concerns regarding the respiratory health effects of airborne particulate matter (PM) after the destruction of the World Trade Centre (WTC). We examined cytokine (interleukin [IL]-8, IL-6, tumor necrosis factor-alpha) release by primary human lung alveolar macrophages (AM) and type II epithelial cells after exposure to WTC PM2.5 (indoor and outdoor), PM10-2.5 (indoor), and PM53-10 (outdoor), fractionated from settled dusts within 2 months of the incident. There was an increase in AM cytokine/chemokine release at 5 and/or 50 microg/well WTC PM, which fell at 500 microg/well. Type II cells did not release tumor necrosis factor-alpha, and the increase in IL-8 and IL-6, although significant, was lower than that of AM. Respirable PM generated by the WTC collapse stimulates inflammatory mediator release by lung cells, which may contribute to the increased incidence of respiratory illness since September 11th 2001.

Host specificity of Trypanosoma (Herpetosoma) species: evidence that bank voles (Clethrionomys glareolus) carry only one T. (H.) evotomys 18S rRNA genotype but wood mice (Apodemus sylvaticus) carry at least two polyphyletic parasites.

The strongest evidence for host specificity of mammalian trypanosomes comes from parasites of the subgenus Trypanosoma (Herpetosoma). Laboratory studies have shown that T. (Herpetosoma) species will not infect an alternative host. However, this has not been demonstrated in wild populations. We screened 560 bank voles (Clethrionomys glareolus) and 148 wood mice (Apodemus sylvaticus) for trypanosomes by PCR amplification of the 18S rRNA gene. In total, 109 (19%) bank voles and 12 (8%) wood mice were infected. A HaeIII restriction site was discovered that could be used to discriminate between T. (H.) evotomys of the bank vole and T. (H.) grosi of the wood mouse. All the parasites in the bank voles were identified as T. (Herpetosoma) evotomys by RFLP-PCR. Out of the 12 wood mouse infections 10 were due to T. grosi. Two of the wood mice were infected with parasites with a novel genotype that was most similar to those of T. evotomys and T. microti of voles. Fifty-six fleas collected from the rodents were also screened for trypanosomes; 9 were infected with T. evotomys and 1 with T. grosi. One of the fleas infected with T. evotomys was collected from a wood mouse.

Copper toxicosis in the Bedlington terrier: a diagnostic dilemma.

Diagnosis of copper toxicosis (CT) in Bedlington terriers by the quantitative and qualitative assessment of copper (Cu) in, and pathology of, biopsies has been largely superseded by a DNA-based assay which uses a microsatellite marker (C04107) linked to the CT disease allele. A retrospective study was conducted comprising 154 liver biopsies from Bedlington terriers with 22 matched DNA markers to compare the two methods in the diagnosis of CT. For the biopsy method, three categories (phenotypes) were identified based on analytical and morphological criteria: 'unaffected' in 83 samples (54 per cent), where Cu was much less than 400 microg/g, and there was an absence of visual Cu or liver damage; 'intermediate' in 18 samples (12 per cent), where Cu was less than 400 microg/g, and there was limited histochemical Cu and no/equivocal damage; and 'affected' in 53 samples (34 per cent), where Cu was greater than 400 microg/g, there was histochemical Cu and liver damage was poorly related to Cu content. In the DNA assay, which was used alone on unrelated individuals, the microsatellite marker failed to identify the CT status of any of the groups. Liver biopsy remains a reliable indicator of Cu accumulation and progressive liver disease in individual dogs. The microsatellite marker C04107 has a predictive value only when supported by a pedigree.

Polymorphism at the bovine tumor necrosis factor alpha locus and assignment to BTA 23.

We have identified four single-strand conformation variants of the bovine tumor necrosis factor alpha gene by analysis of PCR-amplified fragments. The variants are inherited in Mendelian fashion and are informative for linkage mapping. We have mapped the bovine gene to Chromosome (Chr) 23 in a panel of somatic cell hybrids and observed genetic linkage to the major histocompatibility complex (BoLA) genes and microsatellite markers on bovine Chr 23 in an international bovine reference family panel. The distribution of the alleles was determined in cattle of different breeds and of different geographical origins, which included trypano-susceptible and trypano-tolerant cattle.

Parasite strain specificity of bovine cytotoxic T cell responses to Theileria parva is determined primarily by immunodominance.

The parasite strain specificity of CTL responses to Theileria parva varies among cattle immunized with the same parasite stock. We have investigated the influence of class I MHC on the strain specificity of CTL responses to T. parva in 19 cattle of defined class I phenotype immunized with either of two T. parva populations, in which protection to subsequent reciprocal challenge correlated with CTL strain specificity. In the majority of animals the response was restricted by the products of one MHC haplotype and there was a consistent bias to some haplotypes in preference to others. In 10 of 13 cattle expressing the molecularly defined MHC specificities A10 and KN104 on one haplotype, the CTL response was restricted entirely by this haplotype, thus allowing a precise analysis of the MHC restriction specificities. The MHC restriction specificity and the parasite population used for immunization both influenced the strain specificity of the response. By examining responses in identical twins immunized with different parasites or in animals before and after challenge with heterologous parasites, animals that mounted a strain-specific response to primary infection were shown to be capable of responding to Ags shared by the two parasite populations. These findings indicate that the strain specificity of CTL responses to T. parva is not determined primarily by immune response genes that define the inherent capacity to respond, but rather is a consequence of the response in individual animals being biased toward a limited number of immunodominant peptide-MHC determinants.

Sesamoid arthrodesis for hyperextension of the thumb metacarpophalangeal joint.

Forty-two sesamoid arthrodeses performed since 1986 were reviewed. Thirty-seven cases were considered successful. Hypertension recurred in 3 of the 20 procedures performed for cerebral palsy and 1 of the 21 performed in association with basal joint arthroplasty for arthritic conditions. The single post trauma case was successful. Flexion was preserved. Prevention of hyperextension of the metacarpophalangeal joint assists in reducing metacarpal adduction in cerebral palsy and has a stabilizing effect in basal joint arthroplasty.

Cytotoxic T-cells elicited in cattle challenged with Theileria parva (Muguga): evidence for restriction by class I MHC determinants and parasite strain specificity.

The MHC restriction and parasite strain specificity of cytotoxic cells elicited in a group of Theileria parva (Muguga)-immunized cattle following homologous challenge, were investigated. The cytotoxic cells were specific for parasitized target cells and in 9 of the 10 animals examined, they were clearly genetically restricted. Cytotoxicity could be inhibited by monoclonal antibodies (MoAb) to class I MHC molecules but not by MoAb to class II molecules, indicating that a large component of the response was restricted by class I MHC determinants. Low levels of inhibition of cytotoxicity were also obtained with a MoAb to the T-cell subset marker BoT8, suggesting that at least part of the response was mediated by BoT8+ lymphocytes. When cytotoxic cells from individual cattle were assayed on panels of parasitized target cells, there was a close correlation between susceptibility of the target cells to lysis and sharing of BoLA-A locus-encoded specificities with the effectors. This observation, taken together with the knowledge that within several of the sets of BoLA-A-matched targets the relevant BoLA-A specificities were on different MHC haplotypes, indicated that the responses were restricted predominantly by BoLA-A products. In individual cattle there was a striking bias in the restriction of the response to one or other BoLA-A specificity. Among the six specificities represented, responses restricted by w6, w8 and KN18 consistently predominated over responses restricted by w7, w10 and w11. In the three cattle tested for parasite strain specificity, two showed complete specificity and one partial specificity for cells infected with the parasite stock used for immunization, T. parva (Muguga).