Inheritance of cholesterol metabolism of probands with high or low cholesterol absorption

Heredity of cholesterol absorption and synthesis was studied in siblings of hypercholesterolemic probands with low and high serum cholestanol to cholesterol ratio (assumed to indicate low and high absorption of cholesterol, respectively). Cholesterol synthesis was assayed with sterol balance technique and measuring serum cholesterol precursor to cholesterol ratios (synthesis markers of cholesterol), and cholesterol absorption with measuring dietary cholesterol absorption percentage and serum plant sterol and cholestanol to cholesterol ratios (absorption markers of cholesterol). In the siblings of the low absorption families, cholesterol absorption percentage and ratios of absorption markers were significantly lower, and cholesterol and bile acid synthesis, cholesterol turnover, fecal steroids and ratios of synthesis markers significantly higher than in the siblings of the high absorption families. The ratios of absorption and synthesis markers were inversely interrelated, and they were correlated with cholesterol absorption and synthesis in the siblings. In addition, low absorption was associated with high body mass index, low HDL cholesterol, and serum sex hormone binding globulin levels, suggesting that low absorption was associated with metabolic syndrome. Intrafamily correlations were significant for serum synthesis markers, cholestanol, triglycerides, and blood glucose level. In conclusion, cholesterol absorption efficiency and synthesis are partly inherited phenomena, and they can be predicted by the ratios of non-cholesterol sterols to cholesterol in serum.     

Successful immunotherapy with matrix metalloproteinase-derived peptides in adjuvant arthritis depends on the timing of peptide administration

We have recently found that matrix metalloproteinases (MMPs) are targets for T-cell and B-cell reactivity in experimental arthritis. In the present article, we investigate whether modulation of MMP-specific T-cell responses could influence the course of adjuvant arthritis (AA). Lewis rats were treated nasally with MMP peptides prior to or after AA induction. Administration of the MMP-10 or the MMP-16 peptide prior to AA induction reduced the arthritic symptoms. In contrast, administration of the MMP-10 peptide after AA induction aggravated the arthritic symptoms. The present study shows the possible usefulness of MMP peptides for immunotherapy. However, a clear understanding of proper timing of peptide administration is crucial for the development of such therapies.     

Characterization of the binding site on the formyl peptide receptor using three receptor mutants and analogs of Met-Leu-Phe and Met-Met-Trp-Leu-Leu

The formyl peptide receptor (FPR) is a chemotactic G protein-coupled receptor found on the surface of phagocytes. We have previously shown that the formyl peptide binding site maps to the membrane-spanning region (Miettinen, H. M., Mills, J. S., Gripentrog, J. M., Dratz, E. A., Granger, B. L., and Jesaitis, A. J. (1997) J. Immunol. 159, 4045-4054). Recent reports have indicated that non-formylated peptides, such as MMWLL can also activate this receptor (Chen, J., Bernstein, H. S., Chen, M., Wang, L., Ishi, M., Turck, C. W., and Coughlin, S. R. (1995) J. Biol. Chem. 270, 23398-23401.) Here we show that the selectivity for the binding of different NH(2)-terminal analogs of MMWLL or MLF can be markedly altered by mutating Asp-106 to asparagine or Arg-201 to alanine. Both D106N and R201A produced a similar change in ligand specificity, including an enhanced ability to bind the HIV-1 peptide DP178. In contrast, the mutation R205A exhibited altered specificity at the COOH terminus of fMLF, with R205A binding fMLF-O-butyl > fMLF-O-methyl > fMLF, whereas wt FPR bound fMLF > fMLF-O-methyl approximately fMLF-O-butyl. These data, taken together with our previous finding that the leucine side chain of fMLF is probably bound to FPR near FPR (93)VRK(95) (Mills, J. S., Miettinen, H. M., Barnidge, D., Vlases, M. J., Wimer-Mackin, S., Dratz, E. A., and Jesaitis, A. J. (1998) J. Biol. Chem. 273, 10428-10435.), indicate that the most likely positioning of fMLF in the binding pocket of FPR is approximately parallel to the fifth transmembrane helix with the formamide group of fMLF hydrogen-bonded to both Asp-106 and Arg-201, the leucine side chain pointing toward the second transmembrane region, and the COOH-terminal carboxyl group of fMLF ion-paired with Arg-205.     

Anopheles Midgut Epithelium Evades Human Complement Activity by Capturing Factor H from the Blood Meal

Hematophagous vectors strictly require ingesting blood from their hosts to complete their life cycles. Exposure of the alimentary canal of these vectors to the host immune effectors necessitates efficient counteractive measures by hematophagous vectors. The Anopheles mosquito transmitting the malaria parasite is an example of hematophagous vectors that within seconds can ingest human blood double its weight. The innate immune defense mechanisms, like the complement system, in the human blood should thereby immediately react against foreign cells in the mosquito midgut. A prerequisite for complement activation is that the target cells lack complement regulators on their surfaces. In this work, we analyzed whether human complement is active in the mosquito midgut, and how the mosquito midgut cells protect themselves against complement attack. We found that complement remained active for a considerable time and was able to kill microbes within the mosquito midgut. However, the Anopheles mosquito midgut cells were not injured. These cells were found to protect themselves by capturing factor H, the main soluble inhibitor of the alternative complement pathway. Factor H inhibited complement on the midgut cells by promoting inactivation of C3b to iC3b and preventing the activity of the alternative pathway amplification C3 convertase enzyme. An interference of the FH regulatory activity by monoclonal antibodies, carried to the midgut via blood, resulted in increased mosquito mortality and reduced fecundity. By using a ligand blotting assay, a putative mosquito midgut FH receptor could be detected. Thereby, we have identified a novel mechanism whereby mosquitoes can tolerate human blood.     

Stable Polyglutamine Dimers Can Contain β-Hairpins with Interdigitated Side Chains—But Not α-Helices, β-Nanotubes, β-Pseudohelices,or Steric Zippers

A common thread connecting nine fatal neurodegenerative protein aggregation diseases is an abnormally expanded polyglutamine tract found in the respective proteins. Although the structure of this tract in the large mature aggregates is increasingly well described, its structure in the small early aggregates remains largely unknown. As experimental evidence suggests that the most toxic species along the aggregation pathway are the small early ones, developing strategies to alleviate disease pathology calls for understanding the structure of polyglutamine peptides in the early stages of aggregation. Here, we present a criterion, grounded in available experimental data, that allows for using kinetic stability of dimers to assess whether a given polyglutamine conformer can be on the aggregation path. We then demonstrate that this criterion can be assessed using present-day molecular dynamics simulations. We find that although the α-helical conformer of polyglutamine is very stable, dimers of α-helices lack the kinetic stability necessary to support further oligomerization. Dimers of steric zipper, β-nanotube, and β-pseudohelix conformers are also too short-lived to initiate aggregation. The β-hairpin-containing conformers, instead, invariably form very stable dimers when their side chains are interdigitated. Combining these findings with the implications of recent solid-state NMR data on mature fibrils, we propose a possible pathway for the initial stages of polyglutamine aggregation, in which β-hairpin-containing conformers act as templates for fibril formation.     

Reliability of an injury scoring system for horses

Background

The risk of injuries is of major concern when keeping horses in groups and there is a need for a system to record external injuries in a standardised and simple way. The objective of this study, therefore, was to develop and validate a system for injury recording in horses and to test its reliability and feasibility under field conditions.

Methods

Injuries were classified into five categories according to severity. The scoring system was tested for intra- and inter-observer agreement as well as agreement with a 'golden standard' (diagnosis established by a veterinarian). The scoring was done by 43 agricultural students who classified 40 photographs presented to them twice in a random order, 10 days apart. Attribute agreement analysis was performed using Kendall's coefficient of concordance (Kendall's W), Kendall's correlation coefficient (Kendall's τ) and Fleiss' kappa. The system was also tested on a sample of 100 horses kept in groups where injury location was recorded as well.

Results

Intra-observer agreement showed Kendall's W ranging from 0.94 to 0.99 and 86% of observers had kappa values above 0.66 (substantial agreement). Inter-observer agreement had an overall Kendall's W of 0.91 and the mean kappa value was 0.59 (moderate). Agreement for all observers versus the 'golden standard' had Kendall's τ of 0.88 and the mean kappa value was 0.66 (substantial). The system was easy to use for trained persons under field conditions. Injuries of the more serious categories were not found in the field trial.

Conclusion

The proposed injury scoring system is easy to learn and use also for people without a veterinary education, it shows high reliability, and it is clinically useful. The injury scoring system could be a valuable tool in future clinical and epidemiological studies.

     

Diffusion is capable of translating anisotropic apoptosis initiation into a homogeneous execution of cell death

Background  

Apoptosis is an essential cell death process throughout the entire life span of all metazoans and its deregulation in humans has been implicated in many proliferative and degenerative diseases. Mitochondrial outer membrane permeabilisation (MOMP) and activation of effector caspases are key processes during apoptosis signalling. MOMP can be subject to spatial coordination in human cancer cells, resulting in intracellular waves of cytochrome-c release. To investigate the consequences of these spatial anisotropies in mitochondrial permeabilisation on subsequent effector caspase activation, we devised a mathematical reaction-diffusion model building on a set of partial differential equations.     

<Emphasis Type="Italic">TRAF1/C5</Emphasis>polymorphism is not associated with increased mortality in rheumatoid arthritis: two large longitudinal studies

Introduction  

Recently an association between a genetic variation in TRAF1/C5 and mortality from sepsis or cancer was found in rheumatoid arthritis (RA). The most prevalent cause of death, cardiovascular disease, may have been missed in that study, since patients were enrolled at an advanced disease stage. Therefore, we used an inception cohort of RA patients to investigate the association between TRAF1/C5 and cardiovascular mortality, and replicate the findings on all-cause mortality. As TRAF1/C5 associated mortality may not be restricted to RA, we also studied a large cohort of non-RA patients.