The onset of atherosclerotic lesion formation in hypercholesterolemic rabbits is delayed by iron depletion.

The theory that iron may play a significant role in atherogenesis by promoting the formation of free radicals is controversial. Previous results using the new technique of nuclear microscopy showed a seven-fold increase in iron concentrations within newly formed atherosclerotic lesions in hypercholesterolemic rabbits compared to healthy artery tissue. In a follow-up time sequence study described here, we show that iron accumulation occurs at the onset of lesion formation. In addition, weekly bleeding decreases the iron uptake into the artery wall and delays the onset of atherogenesis. These results provide direct evidence for a key role of iron in initiating atherogenesis.     

In vitro sensitivity of virulent Acanthamoeba culbertsoni to a variety of drugs and antibiotics

Ferrante A., Rowan-Kelly B. and Thong Y. H. 1984. In vitro sensitivity of virulent Acanthamoeba culbertsoni to a variety of drugs and antibiotics. International Journal for Parasitology14: 53–56. Effective chemotherapy for diseases caused by species of Acanthamoeba has been hampered because of the marked resistance of these amoebae to a variety of antimicrobial agents. In the present study, we investigated the sensitivity of A. culbertsoni to a spectrum of antimicrobial agents previously not examined against either A. culbertsoni or other species of Acanthamoeba. The antimicrobial agents previously not tested against Acanthamoeba species displayed either little or no activity; isoniazid, rifamycin, tinidazole and rolitetracycline, marginal activity; primaquine, or strong activity; ketoconazole, mefloquine, colistin (polymixin E) and AmB methyl ester. Interestingly, the amoeba showed marked sensitivity to colistin (MIC = 0–0195 μg/ml).     

A solid-phase synthesis of three aza-, iminoaza- and reduced aza-peptides from the same precursor

Summary Using the Boc-strategy, a step-by-step synthesis on the PAM solid support of three aza-, iminoaza- and reduced aza-peptide homologues is described. From the same hydrazinocarbonyl peptide-PAM precursor, the coupling of either a Boc-amino acid or a Boc-amino aldehyde gives rise to an aza-peptide or an iminoaza-peptide, containing the C^α-CO-NH-N^α-CO-NH-C^α or C^α-CH=N-N^α-CO-NH-C^α surrogate, of the peptide motif, respetively. In situ reduction of the latter by NaBH₃CN leads to a reduced aza-peptide containing the C^α-CH₂-NH-N^α-CO-NH-C^α moiety. The key step synthesis of the hydrazinocarbonyl peptide-PAM precursor is carried out by coupling on the growing peptide chain theN-Boc-azaamino acid chloride obtained by the action of triphosgene on the, correspondingN-Boc-hydrazine. These modifications have been introduced in position 1–2 of the YLGYLEQLLR benzodiazepine-like decapeptide.     

Sociodemographic and motivational characteristics of parents who volunteer their children for clinical research: a controlled study.

OBJECTIVE--To determine the sociodemographic and motivational characteristics of parents who volunteer their children for clinical research. DESIGN--A questionnaire was administered to parents who volunteered their children for a randomised, double blind, placebo controlled trial of a drug to treat asthma and to a control group of parents whose children were eligible for the trial but had refused the invitation. SETTING--A children''s hospital in Australia. SUBJECTS--68 Parents who had volunteered their children and 42 who had not; a response rate of 94% and 70%, respectively. MAIN OUTCOME MEASURES--Responses of parents to questionnaire designed to assess their perceptions, attitudes, and health seeking behaviour as well as sociodemographic data. RESULTS--Volunteering parents were less well educated with only 15% (10/68) of mothers and 16% (11/68) and of fathers having had a tertiary or university education compared with 26% (11/42) of mothers and 45% (19/42) in the non-volunteering group. Fewer volunteering parents had professional or administrative jobs than did non-volunteering parents (mothers 6% (4/68); fathers 9% (6/68) v mothers 14% (6/42); fathers 31% (13/42)). Volunteering parents had less social support, and they displayed greater health seeking behaviour and consumed more habit forming substances. They were motivated by a desire to help others and to contribute to medical research, but they were also searching for more information and better ways to help their own children. CONCLUSION--Parents who volunteer their children for medical research are significantly more socially disadvantaged and emotionally vulnerable.     

Conformational disturbance induced by AzPro/Pro substitution in peptides

Summary Consequences inherent to the substitution of aza-proline (AzPro) for proline in the octapeptide TTSAPTTS, representative of the tandem repeat motif present in the peptide backbone of MUC5AC mucin, were analysed in terms of conformational perturbation and O-glycosylation aptitude. In DMSO solution, we observed the same tendency previously noted in AzPro-tripeptide models, i.e. AzPro prevents β-turn formation in which it would occupy the i+1 position, and therefore behaves quite opposite to Pro, whereas both AzPro and Pro can support a β-turn in the i+2 position with a cis disposition of the preceding tertiary amide function. The former structural modifications do not prevent O-glycosylation to take place at the same specific site, but it occurs at a reduced rate.     

Conformational requirements for molecular recognition of acetylcholine receptor main immunogenic region (MIR) analogues by monoclonal anti-MIR antibody: A two-dimensional nuclear magnetic resonance and molecular dynamics approach

The conformational properties of two [D -A⁷⁰, A⁷⁶] and [Aib⁷⁰, A⁷⁶] analogues of the α67–76 Torpedo acetylcholine receptor fragment, with low binding capacity for the anti main immunogenic region (MIR) antibodies, were studied in DMSO by two-dimensional nmr techniques and molecular dynamics simulations. The results were compared to the free and bound conformations of the [A⁷⁶] analogue, which has twice more affinity for the anti-MIR monoclonal antibody 6 (mAb6), than the natural Torpedo sequence. It appeared that a single substitution of the A⁷⁰, at a crucial position, by the D -A⁷⁰ or Aib⁷⁰, could modify completely the conformational behavior of the peptide and reduced its recognition by the anti-MIR antibody. The WNPADY rigid structure at the N-terminal part was essential for antibody recognition. The adjacent more flexible C-terminal sequence (GGIK) gives additional stability to the monoclonal antibody–peptide complex probably due to an adequate orientation of the peptide side chains in the complex, by setting them in close contact with the antibody. © 1993 John Wiley & Sons, Inc.     

Latent likelihood ratio tests for assessing spatial kernels in epidemic models

One of the most important issues in the critical assessment of spatio-temporal stochastic models for epidemics is the selection of the transmission kernel used to represent the relationship between infectious challenge and spatial separation of infected and susceptible hosts. As the design of control strategies is often based on an assessment of the distance over which transmission can realistically occur and estimation of this distance is very sensitive to the choice of kernel function, it is important that models used to inform control strategies can be scrutinised in the light of observation in order to elicit possible evidence against the selected kernel function. While a range of approaches to model criticism is in existence, the field remains one in which the need for further research is recognised. In this paper, building on earlier contributions by the authors, we introduce a new approach to assessing the validity of spatial kernels—the latent likelihood ratio tests—which use likelihood-based discrepancy variables that can be used to compare the fit of competing models, and compare the capacity of this approach to detect model mis-specification with that of tests based on the use of infection-link residuals. We demonstrate that the new approach can be used to formulate tests with greater power than infection-link residuals to detect kernel mis-specification particularly when the degree of mis-specification is modest. This new tests avoid the use of a fully Bayesian approach which may introduce undesirable complications related to computational complexity and prior sensitivity.

     

A simplified method for the efficient purification and refolding of recombinant human TRAIL

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) belongs to the TNF cytokine superfamily that specifically induces apoptosis in a broad spectrum of human cancer cell lines but not in most healthy cells. The antitumor potential of recombinant human TRAIL (rhTRAIL) has attracted great attention among biologists and oncologists. However, attempts to express rhTRAIL in Escherichia coli often results in limited yield of bioactive protein due to the formation of inclusion bodies (IBs), which are dense insoluble particulate protein aggregates inside cells. We describe herein a highly simplified method to produce pure bioactive rhTRAIL using E. coli. The method is straightforward and requires only basic laboratory equipment, with highly efficient purification and high yield of renaturation, and may also be applied to produce other proteins that form IBs in E. coli.