Delayed-type cutaneous hypersensitivity to melanoma antigens and its implication in active specific immunotherapy in cancer

Summary In this study, we explored whether soluble tumor-cell surface-associated antigens (TAA) might be derived from autochthonous as well as allogeneic sources as immunogens for active specific immunotherapy. Using two popular cell membrane-bound antigen extraction techniques (3 M KCl and isotonic-hypotonic NaCl), we examined the immunogenic potential of such TAA and the specificity of immunologic host reactivity through a delayed-type cutaneous hypersensitivity reaction (DTH) as a guideline for their immunogenic potential in a human malignant melanoma model system. We found that either extraction technique could provide soluble TAA from both autochthonous and allogeneic sources capable of eliciting DTH. While evidence of positive DTH with autochthonous TAA reaffirms the immunogenicity of such TAA, the specificity of host reactivity against TAA derived from allogeneic sources is extremely difficult to establish, even with TAA partially purified by column chromatography in Sephadex G-200. Patients exhibited reactivity to other TAA derived from tumors of different histologies and often to more than one component isolated by column chromatography. Furthermore, when a group of melanoma patients was tested against a panel of melanoma antigens in any random combination, DTH to allogeneic TAA was seen in an unpredictable order and with inconsistent frequency. We conclude, therefore, that while autochthonous antigen immunizations may be justified, more careful studies will be necessary to define the antigenic profile of a given tumor (individual specificity vs shared specificity), establish specificity of alloantigens, and devise suitable methods for testing immunologic specificity for alloantigens, before rational immunotherapy with allogeneic tumor antigens will be feasible.     

Phosphorus eutrophication in the SW Frisian lake district 2. Phosphorus balances and simulation of reduction scenarios

The lakes and interconnecting canals in the S.W. Frisian lake district are highly eutrophic. In the mid-1980's a project on eutrophication and lake restoration research was started. This project was aimed at modelling water transport and phosphorus (P) dynamics and at simulating management scenarios. A simple dynamic P-balance model was used to calculate total phosphorus (TP) balances and to simulate three TP reduction scenarios in each of three lakes: Tjeukemeer, Groote Brekken and Slotermeer. The model covered three periods in 1985, 1986 and 1987. The external loads to Tjeukemeer were highest, moderate to Groote Brekken, and lowest to Slotermeer. The major P sources in the area were discharges from the surrounding polders, used mainly for agriculture, and from IJsselmeer.Despite a 75% TP-reduction in water from the surrounding polders the 0.07 mg l^–1 target level could be reached only occasionally in Tjeukemeer, while in the other two lakes this level was not even approached. The effect of a 75% reduction in water from IJsselmeer was greatest in Groote Brekken (but again approached the target only occasionally), moderate in Tjeukemeer and least in Slotermeer. The simulations showed that only a 75% reduction in both external loads (from polders and from IJsselmeer) will lead to achieving the target level in Tjeukemeer and Groote Brekken during the summer periods. In Slotermeer, a relatively isolated lake, other measures are necessary to reach the target level. The results are confirmed by an approximate theoretical analysis of the effects of load reduction.     

Detecting the coevolution of biosequences--an example of RNA interaction prediction

A probabilistic graphical model is proposed in order to detect the coevolution between different sites in biological sequences. The model extends the continuous-time Markov process of sequence substitution for single nucleic or amino acids and imposes general constraints regarding simultaneous changes on the substitution rate matrix. Given a multiple sequence alignment for each molecule of interest and a phylogenetic tree, the model can predict potential interactions within or between nucleic acids and proteins. Initial validation of the model is carried out using tRNA and 16S rRNA sequence data. The model accurately identifies the secondary interactions of tRNA as well as several known tertiary interactions. In addition, results on 16S rRNA data indicate this general and simple coevolutionary model outperforms several other parametric and nonparametric methods in predicting secondary interactions. Furthermore, the majority of the putative predictions exhibit either direct contact or proximity of the nucleotide pairs in the 3-dimensional structure of the Thermus thermophilus ribosomal small subunit. The results on RNA data suggest a general model of coevolution might be applied to other types of interactions between protein, DNA, and RNA molecules.     

Biochemical markers of ongoing joint damage in rheumatoid arthritis - current and future applications, limitations and opportunities

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease associated with potentially debilitating joint inflammation, as well as altered skeletal bone metabolism and co-morbid conditions. Early diagnosis and aggressive treatment to control disease activity offers the highest likelihood of preserving function and preventing disability. Joint inflammation is characterized by synovitis, osteitis, and/or peri-articular osteopenia, often accompanied by development of subchondral bone erosions, as well as progressive joint space narrowing. Biochemical markers of joint cartilage and bone degradation may enable timely detection and assessment of ongoing joint damage, and their use in facilitating treatment strategies is under investigation. Early detection of joint damage may be assisted by the characterization of biochemical markers that identify patients whose joint damage is progressing rapidly and who are thus most in need of aggressive treatment, and that, alone or in combination, identify those individuals who are likely to respond best to a potential treatment, both in terms of limiting joint damage and relieving symptoms. The aims of this review are to describe currently available biochemical markers of joint metabolism in relation to the pathobiology of joint damage and systemic bone loss in RA; to assess the limitations of, and need for additional, novel biochemical markers in RA and other rheumatic diseases, and the strategies used for assay development; and to examine the feasibility of advancement of personalized health care using biochemical markers to select therapeutic agents to which a patient is most likely to respond.     

UDP-N-acetylglucosamine 4'-epimerase from the intestinal protozoan Giardia intestinalis lacks UDP-glucose 4'-epimerase activity

The protozoan parasite Giardia intestinalis has a simple life cycle consisting of an intestinal trophozoite stage and an environmentally resistant cyst stage. The cyst is formed when a trophozoite encases itself within an external filamentous covering, the cyst wall, which is crucial to the cyst's survival outside of the host. The filaments in the cyst wall consist mainly of a beta (1-3) polymer of N-acetylgalactosamine. Its precursor, UDP-N-acetylgalactosamine, is synthesized from fructose 6-phosphate by a pathway of five inducible enzymes. The fifth, UDP-N-acetylglucosamine 4'-epimerase, epimerizes UDP-N-acetylglucosamine to UDP-N-acetylgalactosamine reversibly. The epimerase of G. intestinalis lacks UDP-glucose/UDP-galactose 4'-epimerase activity and shows characteristic amino acyl residues to allow binding of only the larger UDP-N-acetylhexosamines. While the Giardia epimerase catalyzes the reversible epimerization of UDP-N-acetylglucosamine to UDP-N-acetylgalactosamine, the reverse reaction apparently is favored. The enzyme has a higher Vmax and a smaller Km in this direction. Therefore, an excess of UDP-N-acetylglucosamine is required to drive the reaction towards the synthesis of UDP-N-acetylgalactosamine, when it is needed for cyst wall formation. This forms the ultimate regulatory step in cyst wall biosynthesis.     

Structure and binding analysis of Polyporus squamosus lectin in complex with the Neu5Ac{alpha}2-6Gal{beta}1-4GlcNAc human-type influenza receptor

Glycan chains that terminate in sialic acid (Neu5Ac) are frequently the receptors targeted by pathogens for initial adhesion. Carbohydrate-binding proteins (lectins) with specificity for Neu5Ac are particularly useful in the detection and isolation of sialylated glycoconjugates, such as those associated with pathogen adhesion as well as those characteristic of several diseases including cancer. Structural studies of lectins are essential in order to understand the origin of their specificity, which is particularly important when employing such reagents as diagnostic tools. Here, we report a crystallographic and molecular dynamics (MD) analysis of a lectin from Polyporus squamosus (PSL) that is specific for glycans terminating with the sequence Neu5Acα2-6Galβ. Because of its importance as a histological reagent, the PSL structure was solved (to 1.7??) in complex with a trisaccharide, whose sequence (Neu5Acα2-6Galβ1-4GlcNAc) is exploited by influenza A hemagglutinin for viral adhesion to human tissue. The structural data illuminate the origin of the high specificity of PSL for the Neu5Acα2-6Gal sequence. Theoretical binding free energies derived from the MD data confirm the key interactions identified crystallographically and provide additional insight into the relative contributions from each amino acid, as well as estimates of the importance of entropic and enthalpic contributions to binding.     

Oxidative stress in myocardial ischaemia reperfusion injury: a renewed focus on a long-standing area of heart research

Advances in the treatment of coronary artery disease have seen a significant drop in mortality and morbidity particularly amongst patients with acute myocardial infarction (MI). In particular, percutaneous trans-luminal balloon angioplasty (PTCA) with stenting to re-open atherosclerotic coronary arteries has yielded marked improvement in clinical outcome for patients with acute MI. Furthermore, with the advent of drug-eluting stents occurrence rates for coronary artery restenosis, one common clinical problem associated with angioplasty and stent deployment, have declined markedly. However, coronary restenosis in diabetic patients remains an on-going problem. The success of drug-eluting stents has seen a renewed focus on myocardial ischaemia reperfusion (IR) injury as this represents one area of research where many questions remain unanswered. In particular, the relationship between myocardial IR injury and decreased myocardial micro-vasculature re-flow post PTCA (that ultimately leads to poor clinical outcome and myocardial damage/dysfunction) is one area of research with the potential to decrease current complication rates further in patients suffering myocardial IR injury sustained during MI. This review discusses the role for oxidative stress, oxidant source(s) and both gene regulation and stem-cell therapy as potential strategic targets in the ischaemic myocardium, with the ultimate aim of providing significant cardioprotection in the setting of acute MI.     

Impalement of marine turtles (Reptitia,Chelonia: Cheloniidae and Dermochelyidae) by billfishes (Osteichthyes,Perciformes: Istiophoridae and Xiphiidae)

Synopsis Billfishes have long been known to impale a great variety of objects, but there are only two brief, obscure records of marine turtles being speared. Details are presented on these two, as well as on two other confirmed records; data from two additional unconfirmed records are also presented. In total, three species of marine turtles are known to have been impaled by three species of billfishes; a fourth species of fish and a fourth species turtle are listed in an unconfirmed case. Records come from the eastern and western Pacific as well as the eastern Atlantic. Of the four confirmed cases, the turtles survived in two, and apparently died as an effect of the spearing in the other two. In three confirmed cases only the impaled rostrum was encountered, and in one confirmed case the entire fish was found, with its rostrum piercing the turtle. There is no obvious advantage — or clear disadvantage — involved in impaling turtles. It is argued that these attacks are accidental, and the result of attempts made by the billfish to capture prey that are near the turtle. These spearings indicate that the chelonians serve as shelters for prey animals on the high seas, and thus, are further evidence of the pelagic existence of marine turtles. The impalings are evidence of a singular ecological role of the turtles — as live fish aggregation devices.