Experimental human infection with the dog hookworm, Ancylostoma caninum

Objective: To investigate possible routes for human infection by the dog hookworm (Ancylostoma caninum). Design, setting and participant. Relatively small numbers of infective larvae were administered orally and percutaneously to an informed healthy volunteer (J K L) under medical supervision, at intervals between May 1998 and May 1999. Main outcome measures: Symptoms; weekly blood eosinophil counts; faecal microscopy. Results: A marked blood eosinophilia followed a single oral exposure to 100 infective larvae, while faecal examination remained negative. Eosinophil counts then declined gradually, although a rapid, spontaneous rise several months later, at the beginning of spring, possibly indicated reactivation of dormant larvae. Blood eosinophil numbers did not rise significantly after percutaneous infection with 200 larvae. A subsequent, smaller, oral inoculum of 20 larvae provoked an eosinophil response similar to that of the first experiment. Conclusions: Our findings suggest that, following ingestion, some infective larvae of A. caninum develop directly into adult worms in the human gut (as they do in dogs). While the percutaneous route might be the most common means of human exposure to canine hookworm larvae, leading generally to subclinical infection, oral infection may be more likely to provoke symptomatic eosinophilic enteritis.

Kinetic parameters associated with self-heating of New Zealand coals under adiabatic conditions

Adiabatic self-heating tests were carried out on five New Zealand coal samples ranging in rank from lignite to high-volatile bituminous. Kinetic parameters of oxidation were obtained front the self-heating curves assuming Arrhenius behaviour. The activation energy E (kJ mol(-1)) and the pre-exponential factor A (s(-1)) were determined in the temperature range of 70-140 degreesC. The activation energy exhibited a definite rank relationship with a minimum E of 55 kJ mol(-1) occurring at a Suggate rank of similar to6.2 corresponding to subbituminous C. Either side of this rank there was a noticeable increase in the activation energy indicating lower reactivity of the coal. A similar rank trend was also observed in the R-70 self-heating rate index values that were taken from the initial portion of the self-heating curve front 40 to 70 degreesC. From these results it is clear that the adiabatic method is capable of providing reliable kinetic parameters of coal oxidation.

Sox18 mutations in the ragged mouse alleles ragged-like and opossum

The ragged (Ra) spontaneous mouse mutant is characterised by abnormalities in its coat and cardiovascular system. Four alleles are known and we have previously described mutations in the transcription factor gene Sox18 in the Ra and Ra-J alleles. We report here Sox18 mutations in the remaining two ragged alleles, opossum (Ra-op) and ragged-like (Ragl). The single-base deletions cause a C-terminal frameshift, abolishing transcriptional trans-activation and impairing interaction with the partner protein MEF2C. The nature of these mutations, together with the near-normal phenotype of Sox18-null mice, suggests that the ragged mutant SOX18 proteins act in a dominant-negative fashion. The four ragged mutants represent an allelic series that reveal SOX18 structure-function relationships and implicate related SOX proteins in cardiovascular and hair follicle development. (C) 2003 Wiley-Liss, Inc.

Early pregnancy factor suppresses the infiltration of lymphocytes and macrophages in the spinal cord of rats during experimental autoimmune encephalomyelitis but has no effect on apoptosis

Early pregnancy factor (EPF) is a secreted protein with immunosuppressive and growth factor properties that has been shown to suppress acute experimental autoimmune encephalomyelitis (EAE) induced with myelin basic protein (MBP) in Lewis rats. EAE is associated with infiltration of the central nervous system (CNS) with inflammatory cells. Spontaneous recovery involves the loss of T lymphocytes from the CNS and the selective apoptosis of Vbeta8.2(+) cells. In the present study, T cell, macrophage (CD11b/c(+)) and B cell (CD45RA(+)) populations in spinal cord and popliteal lymph nodes (LN) of Lewis rats with EAE were quantitated and apoptosis was studied. Rats were treated with EPF or vehicle. Following treatment on day 14 after inoculation with MBP, neither 1 x 100 mug nor 2 x 100 mug doses of EPF affected the total number of cells infiltrating the spinal cord on day 15, although the higher dose caused a decrease in the number of CD5(+) and CD11b/c(+) cells. Treatment with 2 x 100 mug/day from days 10 to 14 decreased the total number of infiltrating cells, and the numbers of CD5(+), CD11b/c(+) and CD45RA(+) cells. Apoptosis was unaffected. No alteration on the number or type of inflammatory cells in the popliteal LN was observed after treatment on days 10-14. However, treatment with EPF from days 0 to 11 increased the total number of T and B cells and CD5(+) T cells found on day 12 in the LN. Similarly, there was an increase in the frequency of MBP-reactive cells in the LN as determined by limiting dilution analysis. These results suggest that EPF treatment reduces the numbers of lymphocytes and macrophages in the CNS, possibly through an effect on cell trafficking. (C) 2003 Elsevier B.V. All rights reserved.

Synthesis and characterization of delta-atracotoxin-ar1a, the lethal neurotoxin from venom of the Sydney funnel-web spider (Atrax robustus)

delta-Atracotoxin-Ar1a (delta-ACTX-Ar1a) is the major polypeptide neurotoxin isolated from the venom of the male Sydney funnel-web spider, Atrax robustus. This neurotoxin targets both insect and mammalian voltage-gated sodium channels, where it competes with scorpion alpha-toxins for neurotoxin receptor site-3 to slow sodium-channel inactivation. Progress in characterizing the structure and mechanism of action of this toxin has been hampered by the limited supply of pure toxin from natural sources. In this paper, we describe the first successful chemical synthesis and oxidative refolding of the four-disulfide bond containing delta-ACTX-Ar1a. This synthesis involved solid-phase Boc chemistry using double coupling, followed by oxidative folding of purified peptide using a buffer of 2 M GdnHCl and glutathione/glutathiol in a 1:1 mixture of 2-propanol (pH 8.5). Successful oxidation and refolding was confirmed using both chemical and pharmacological characterization. Ion spray mass spectrometry was employed to confirm the molecular weight. H-1 NMR analysis showed identical chemical shifts for native and synthetic toxins, indicating that the synthetic toxin adopts the native fold. Pharmacological studies employing whole-cell patch clamp recordings from rat dorsal root ganglion neurons confirmed that synthetic delta-ACTX-Ar1a produced a slowing of the sodium current inactivation and hyperpolarizing shifts in the voltage-dependence of activation and inactivation similar to native toxin. Under current clamp conditions, we show for the first time that delta-ACTX-Ar1a produces spontaneous repetitive plateau potentials underlying the clinical symptoms seen during envenomation. This successful oxidative refolding of synthetic delta-ACTX-Ar1a paves the way for future structure-activity studies to determine the toxin pharmacophore.

Microscopic structure of opalescent and nonopalescent pecans

The ultrastructure of pecans was investigated using light microscopy, environmental scanning electron microscopy, scanning electron microscopy, and transmission electron microscopy. Specific methodology for the sample preparation of pecans for electron microscopy investigations was developed. Electron microscopy of the ultrastructure of opalescent (discoloration of the interior) and nonopalescent kernels revealed that cellular damage was occurring in opalescent kernels. The damage was due to cell wall and membrane rupture, which accounted for the release of oil throughout the kernel. This rupture is due to the lower level of calcium in the cell membranes of opalescent pecans, as shown by energy dispersive X-ray spectrometry, making them more susceptible to damage.