Endovascular repair of acute uncomplicated aortic type B dissection promotes aortic remodelling: 1 year results of the ADSORB trial.

OBJECTIVES: Uncomplicated acute type B aortic dissection (AD) treated conservatively has a 10% 30-day mortality and up to 25% need intervention within 4 years. In complicated AD, stent grafts have been encouraging. The aim of the present prospective randomised trial was to compare best medical treatment (BMT) with BMT and Gore TAG stent graft in patients with uncomplicated AD. The primary endpoint was a combination of incomplete/no false lumen thrombosis, aortic dilatation, or aortic rupture at 1 year. METHODS: The AD history had to be less than 14 days, and exclusion criteria were rupture, impending rupture, malperfusion. Of the 61 patients randomised, 80% were DeBakey type IIIB. RESULTS: Thirty-one patients were randomised to the BMT group and 30 to the BMT+TAG group. Mean age was 63 years for both groups. The left subclavian artery was completely covered in 47% and in part in 17% of the cases. During the first 30 days, no deaths occurred in either group, but there were three crossovers from the BMT to the BMT+TAG group, all due to progression of disease within 1 week. There were two withdrawals from the BMT+TAG group. At the 1-year follow up there had been another two failures in the BMT group: one malperfusion and one aneurysm formation (p = .056 for all). One death occurred in the BMT+TAG group. For the overall endpoint BMT+TAG was significantly different from BMT only (p < .001). Incomplete false lumen thrombosis, was found in 13 (43%) of the TAG+BMT group and 30 (97%) of the BMT group (p < .001). The false lumen reduced in size in the BMT+TAG group (p < .001) whereas in the BMT group it increased. The true lumen increased in the BMT+TAG (p < .001) whereas in the BMT group it remained unchanged. The overall transverse diameter was the same at the beginning and after 1 year in the BMT group (42.1 mm), but in the BMT+TAG it decreased (38.8 mm; p = .062). CONCLUSIONS: Uncomplicated AD can be safely treated with the Gore TAG device. Remodelling with thrombosis of the false lumen and reduction of its diameter is induced by the stent graft, but long term results are needed.

Human IgE against the major allergen Bet v 1--defining an epitope with limited cross-reactivity between different PR-10 family proteins.

BACKGROUND: The interaction between IgE and allergen is a key event at the initiation of an allergic response, and its characteristics have substantial effects on the clinical manifestation. Despite this, the molecular details of the interaction between human IgE and the major birch allergen Bet v 1, one of the most potent tree allergens, still remain poorly investigated. OBJECTIVE: To isolate Bet v 1-specific human monoclonal IgE and characterize their interaction with the allergen. METHODS: Recombinant human IgE were isolated from a combinatorial antibody fragment library and their interaction with Bet v 1 assessed using various immunological assays. The structure of one such IgE in the single-chain fragment variable format was determined using X-ray crystallography. RESULTS: We present four novel Bet v 1-specific IgE, for one of which we solve the structure, all with their genetic origin in the IGHV5 germline gene, and demonstrate that they target two non-overlapping epitopes on the surface of Bet v 1, thereby fulfilling the basic criteria for FcεRI cross-linkage. We further define these epitopes and for one epitope pinpoint single amino acid residues important for the interaction with human IgE. This provides a potential explanation, at the molecular level, for the differences in recognition of isoforms of Bet v 1 and other allergens in the PR-10 protein family displayed by IgE targeting this epitope. Finally, we present the first high-resolution structure of a human allergen-specific IgE fragment in the single-chain fragment variable (scFv) format. CONCLUSIONS AND CLINICAL RELEVANCE: We here display the usefulness of allergen-specific human monoclonal IgE as a tool in studies of the crucial molecular interaction taking place at the initiation of an allergic response. Such studies may aid us in development of better diagnostic tools and guide us in the development of new therapeutic compounds.

Impaired antibody responses but normal proliferation of specific CD4+ T cells in mice lacking complement receptors 1 and 2.

Severely impaired Ab responses are seen in animals lacking C (complement) factors C2, C3 or C4 as well as CR1/2 (C receptors 1 and 2). The molecular mechanism behind this phenomenon is not understood. One possibility is that C-containing immune complexes are endocytosed via CR2 on B cells and presented to specific CD4+ T cells, which would then proliferate and provide efficient help to specific B cells. In vitro, B cells can endocytose immune complexes via CR1/2 and present the Ag to T cells. Whether absence of this Ag presenting function in Cr2(-/-) mice (mice lacking CR1/2) explains their low Ab response is unclear. To address this question, Cr2(-/-) and wild type mice were transferred with OVA-specific T cells, obtained from the DO11.10 strain which has a transgenic TCR recognizing an OVA peptide. The animals were subsequently immunized with sheep red blood cells (SRBC) conjugated to OVA. Interestingly, proliferation of the OVA-specific T cells was normal in Cr2(-/-) mice, although their Ab response to both SRBC and OVA was severely impaired. These observations suggest that the impaired Ab response in Cr2(-/-) mice cannot be explained by a lack of appropriate induction of T cell help.

IgE enhances specific antibody and T-cell responses in mice overexpressing CD23.

IgE administered with its specific antigen in vivo induces enhanced proliferation of specific T cells as well as enhanced production of specific antibodies. Both effects are dependent on the low-affinity receptor for IgE (CD23) and the underlying mechanism is thought to be increased antigen presentation following uptake of IgE/antigen complexes via CD23(+) B cells. By contrast, CD23 negatively regulates antibody responses to antigens administered with alum, i.e. without IgE. This effect has been observed as low IgG1 and IgE responses in transgenic mice overexpressing CD23 (CD23Tg). The present study was designed to test whether IgE could enhance antibody and T-cell responses in CD23Tg animals or whether CD23's downregulatory effect precludes IgE-mediated enhancement. IgE-anti-TNP administered with OVA-TNP enhances the OVA-specific antibody responses in wild-type (wt) and CD23Tg mice equally well. Interestingly, the total magnitude of antibody responses to IgE + OVA-TNP and to uncomplexed OVA-TNP, as well as to sheep erythrocytes and keyhole limpet haemocyanine, were lower in the CD23Tg mice. IgE induced proliferation of OVA-specific CD4(+) T cells to the same degree in wt and CD23Tg mice. The effect on T cells was dependent on CD23(+) B cells as demonstrated in in vitro proliferation assays. In conclusion, CD23 does indeed have dual immunoregulatory effects in the same animal. The receptor mediates enhancement of antibody and T-cell responses to IgE-complexed antigen, most likely via increased presentation of complexed antigen, while it negatively regulates the total antibody response to a variety of antigens.

Antibody-mediated regulation of the immune response.

Antibodies administered in vivo together with the antigen they are specific for can regulate the immune response to that antigen. This phenomenon is called antibody-mediated feedback regulation and has been known for over 100 years. Both passively administered and actively produced antibodies exert immunoregulatory functions. Feedback regulation can be either positive or negative, resulting in >1000-fold enhancement or >99% suppression of the specific antibody response. Usually, the response to the entire antigen is up- or downregulated, regardless of which epitope the regulating antibody recognizes. IgG of all isotypes can suppress responses to large particulate antigens like erythrocytes, a phenomenon used clinically in Rhesus prophylaxis. IgG suppression works in mice lacking the known Fc-gamma receptors (FcgammaR) and a likely mechanism of action is epitope masking. IgG1, IgG2a and IgG2b administered together with soluble protein antigens will enhance antibody and CD4+ T-cell responses via activating FcgammaR, probably via increased antigen presentation by dendritic cells. IgG3 as well as IgM also enhance antibody responses but their effects are dependent on their ability to activate complement. A possible mechanism is increased B-cell activation caused by immune complexes co-crosslinking the B-cell receptor with the complement-receptor 2/CD19 receptor complex, known to lower the threshold for B-cell activation. IgE-antibodies enhance antibody and CD4+ T-cell responses to small soluble proteins. This effect is entirely dependent on the low-affinity receptor for IgE, CD23, the mechanism probably being increased antigen presentation by CD23+ B cells.

IgG3-mediated enhancement of the antibody response is normal in Fc gammaRI-deficient mice.

Antibodies, administered together with their specific antigen, can feedback-regulate antibody responses to this antigen. IgG1, IgG2a and IgG2b enhance antibody responses to soluble protein antigens. This effect is primarily mediated by FcRs as enhancement is impaired in FcR gamma-/- mice, reported to lack Fc gammaRI and Fc gammaRIII because of deletion of the common FcR gamma chain. Also IgG3 can enhance antibody responses. However, this effect is unperturbed in FcR gamma-/- mice but severely impaired in complement-depleted animals and in animals lacking complement receptor 1 and 2. Although this argues against involvement of Fc gammaRs, FcR gamma-/- mice may express one-fifth of the normal levels of Fc gammaRI and, in addition, Fc gammaRI has been suggested to bind IgG3. We re-investigated the dependence of IgG3-mediated enhancement on Fc gammaRs using a mouse strain selectively lacking Fc gammaRI and found that IgG3-mediated enhancement is completely normal. Unlike IgE and IgG2a, which are both thought to enhance T-cell proliferation via FcR-mediated antigen presentation, IgG3 was a poor enhancer of T-cell proliferation both in vivo and in vitro. These findings argue against a significant involvement of Fc gammaRs in IgG3-mediated enhancement of antibody responses and support our previous conclusion that complement plays a major role.

Prevalence of annoyance attributed to electrical equipment and smells in a Swedish population, and relationship with subjective health and daily functioning.

BACKGROUND: Self-reported annoyance from electrical equipment has been in evidence since the mid-1980s, and the first reports of illness from everyday chemicals arose in the 1960s. However, the extent of the problem has not yet been fully established. AIMS: The aim of this study was to estimate the prevalence of annoyance related to electrical and chemical factors in a Swedish general population, and to assess possible relationships with subjective health and daily functioning. METHODS: In total, 13,604 subjects, representative of the population of Scania, Sweden, answered a survey containing five questions regarding annoyance from five environmental factors: fluorescent tube lighting, visual display units, other electrical equipment, air that smells of chemicals, and other smells. The survey also obtained data on self-reported health (SRH-7), mental well-being [General Health Questionnaire (GHQ)-12], work situation and daily functioning. RESULTS: Almost one-third of the respondents reported annoyance from at least one environmental factor. Annoyance was more frequent among women, subjects of working age and immigrants. Subjects who reported environmental annoyance scored higher on GHQ-12 and lower on SRH-7, indicating impaired subjective physical and mental well-being. They were also more likely to report deteriorated daily functioning. CONCLUSIONS: Annoyance related to electrical and/or chemical factors was common in a Swedish population. Subjects reporting environmental annoyance rated their overall health significantly poorer than the general population. The association with subjective health and functional capacity increased with severity of annoyance, which suggests that there is some connection between environmental annoyance, well-being and functional capacity.

Interactions between Local Anaesthetic Agents and Poly(N-isopropyl acrylamide) through Phase Behavior, Surface Tension, and Adsorption Measurement.

The interaction between the local anaesthetic agents prilocaine and lidocaine, on one hand, and poly(N-isopropyl acrylamide) (pNIPAM), on the other, is investigated through studies of the polymer phase behavior and through surface tension and adsorption measurements. In particular, the cloud points (CP) for pNIPAM in the presence of lidocaine and prilocaine under different conditions were compared to the effects of electrolytes and alcohols. It was found that the electrolytes affect the CP of pNIPAM in a lyotropic manner, whereas alcohols depress the CP of pNIPAM in an alkyl chain length dependent way; i.e., the longer the chain, the larger the decrease in CP. Lidocaine and prilocaine affect the CP of pNIPAM in a pH-dependent manner. Below the pK(a) of lidocaine and prilocaine, these cosolutes do not substantially affect the CP in the concentration range investigated, but rather behave analogous to simpler electrolytes. Above the pK(a), on the other hand, they strongly depress the CP already at low concentrations. In parallel, at low pH, the surface tension reduction due to lidocaine or prilocaine is marginal, whereas at high pH the surface tension is reduced considerably. Thus, the poor solubility of prilocaine and lidocaine at high pH causes these to become more surface active and simultaneously interact in a more pronounced way with pNIPAM. Furthermore, it was found from ellipsometry that an adsorbed pNIPAM layer contracts when lidocaine is added, presumably due to a lidocaine-pNIPAM interaction similar to that causing pNIPAM to phase separate. Analogous to this, it was demonstrated that an adsorbed pNIPAM layer shrinks and swells reversibly when the temperature is cycled above and beneath the CP. Copyright 2001 Academic Press.

The selective S-alkylation of a methionine residue in an elapid venom cardiotoxin.

1. The reaction of cardiotoxin with iodoacetamide or iodomethane at pH 3.0 afforded the corresponding methionine sulphonium derivatives. The major products were S-alkylated at Met-26 whilst the minor products were S-alkylated at both Met-24 and -26. 2. Reaction with iodoacetamide under denaturing conditions led to a reversal of the relative abundances of the two derivatives in the respective reaction mixtures. 3. The derivative S-methylated at Met-26 was about 5-fold less toxic than the parent cardiotoxin. That derivatised at both Met-24 and -26 was non-toxic, indicating the importance of Met-24. 4. The results are discussed in the light of a structural model, previous chemical modifications and 1H-NMR data. It appeared that Met-24 is important for the integrity of an important structural feature of cardiotoxin.

Properties of some 3-nitrotyrosyl elapid venom cardiotoxins.

Nitration of the invariant Tyr-22 in Hemachatus haemachates cardiotoxin 12B did not greatly decrease lethality, and the haemolytic potency towards guinea-pig erythrocytes remained unchanged. This residue is thus non-essential for cardiotoxin to exert its biological action. Nitration of Naja haje annulifera and Naja melanoleuca cardiotoxins VII1 decreased but did not abolish the lethalities and haemolytic potencies. Thus Tyr-25 and Tyr-51 were concluded to have no direct functional role in cardiotoxin lethality. The pKa values of the phenolic hydroxyl groups of the tyrosine residues appeared to be important for certain properties of cardiotoxin in solution. No evidence could be produced to show that Tyr-51 is unreactive to nitration under normal (non-denaturing) conditions.

Pharmacological study on angusticeps-type toxins from mamba snake venoms.

Five angusticeps-type toxins, F7, F8 and C10S2C2 from Dendroaspis angusticeps and C and FS2 from D. polylepis polylepis, were tested for action on the chick biventer cervicis nerve-muscle, the frog rectus abdominis muscle and the mouse phrenic nerve-diaphragm preparations. In the chick muscle, none of these toxins exhibited any stimulatory effect up to 100 micrograms/ml. In the frog muscle, the response to acetylcholine, but not to carbachol, was enhanced dose dependently by F7 and C. No appreciable effect was observed with the other three toxins. In the mouse diaphragm, also only F7 and C augmented responses to indirect stimulation and produced spontaneous fasciculations. On tetanic stimulation, a marked Wedensky inhibition was observed. Their stimulatory effect was abolished by d-tubocurarine. In the presence of d-tubocurarine as well as in the denervated mouse diaphragm, neither toxin increased responses to direct stimulation. In low-calcium (0.6 mM) or high magnesium (4.2 mM) medium, the stimulatory effect of both toxins was markedly attenuated. The resting membrane potential of the mouse diaphragm was not changed. The amplitude and frequency of MEPPs and the quantal content and the half-decay time of EPPs was increased. Both toxins also produced a stimulatory effect on the isolated guinea-pig ileum, which was abolished by atropine. In the rat atrial preparation, both toxins caused negative inotropic and chronotropic effects, which were reversed by atropine. If pretreated with atropine, these effects were completely prevented. Both F7 and C markedly inhibited the cholinesterase activity of the homogenized mouse diaphragm and frog rectus abdominis muscle but not that of the chick biventer cervicis muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

1H nuclear-magnetic-resonance studies of the conformation of cardiotoxin VII2 from Naja mossambica mossambica.

The membrane toxin VII2 from the venom of Naja mossambica mossambica was investigated in aqueous solution by one-dimensional and two-dimensional high-resolution nuclear magnetic resonance (NMR) techniques at 360 MHz. The spectral characterization included identification of the complete spin systems for several amino acid residues, nuclear Overhauser effect measurements, the use of chemically induced dynamic nuclear polarization and studies of the pH dependence of the NMR spectrum. Data from homologous toxins, in particular direct lytic factor 12B from Haemachatus haemachatus, were used to establish assignments of aromatic and methyl proton resonances. From these experiments a short, triple-stranded fragment of antiparallel beta structure could be determined, which includes the residues 23-27, 43-46 and 60-62. Furthermore, the nuclear Overhauser effect measurements indicate close proximity in the protein conformation of the aromatic rings of Trp-14, Tyr-25 and Tyr-59, and the side chain of Ile-46.

Purification and some properties of two proteinase inhibitors (DE-1 and DE-3) from Erythrina latissima (broad-leaved erythrina) seed.

Two proteinase inhibitors, DE-1 and DE-3, were purified from Erythrina latissima seeds. Whereas DE-1 inhibits bovine chymotrypsin and not bovine trypsin, DE-3 inhibits trypsin but not chymotrypsin. The molecular weights and the amino acid compositions of the two inhibitors resemble the corresponding properties of the Kunitz-type proteinase inhibitors. The N-terminal primary structure of DE-3 showed homology with soybean trypsin inhibitor (Kunitz) and also with the proteinase inhibitors (A-II and B-II) from Albizzia julibrissin seed.

The preparation of 3-nitrotyrosyl derivatives of three elapid venom cardiotoxins.

Nitration studies using tetranitromethane were conducted on the tyrosine residues of cardiotoxins, naja melanoleuca VII1, Naja haje annulifera VII1 and Hemachatus haemachates toxin 12B. Various partially and fully nitrated derivatives were formed. Analysis of the products of nitrating naja melanoleuca VII1 showed that the average relative reactivities of the three tyrosine residues were Tyr-25 greater than Tyr-22 greater than Tyr-51. It was significant that Tyr-51 could be easily modified in both N. melanoleuca VII1 and N. haje annulifera VII1. In contrast, other workers had found Tyr-51 in N. naja atra cardiotoxin to be unreactive towards tetranitromethane except under denaturing conditions. Fully nitrated derivatives of N. melanoleuca VII1 (Tyr-22, -25 and -51), N haje annulifera VII1 (Tyr-22 and -51) and H. haemachates 12B (Tyr-22), prepared under mild reaction conditions, were isolated by ion-exchange and hydrophobic interaction chromatographies. All three derivatives were pure by disc gel electrophoresis at pH 8.9 and amino acid analysis. They were therefore suitable for spectral and biological studies. The results were compared and contrasted to; those of other workers.

The oxidation of methionine and its effect of the properties of cardiotoxin VII1 from Naja melanoleuca venom.

Methionine residues 24 and 26 of cardiotoxin VII1 from Naja melanoleuca were oxidised to sulphoxides using N-chlorosuccinimide at pH 8.5. The number of equivalents of oxidant required for complete oxidation suggested that the methionine side-chains existed in a relatively "exposed" conformational state in cardiotoxin. The oxidised cardiotoxin was devoid of lethality. It was also non-haemolytic, both on its own and in the presence of phospholipase A2. However, it was still able to precipitate with anti-cardiotoxin antibody. CD studies indicated that the polypeptide backbone conformation was intact in the oxidised cardiotoxin but some perturbation of tyrosine residues was evident. The possibility of a direct or indirect involvement of the methionine residues in the biological activity of the cardiotoxin is discussed.

Snake venom toxins. The primary structure of protein S4C11. A neurotoxin homologue from the venom of forest cobra (Naja melanoleuca).

Six minor protein constituents (S4C10-S4C15) have been isolated from the venom of Naja melanoleuca. The complete amino acid sequence of S4C11 has been established and indicates that it is a homologue of the neurotoxins which are found in elapid venoms. The other proteins appear from the amino acid compositions to be homologues of the cyto- or cardiotoxins found in cobra venoms. Protein S4C11 has a low toxicity, failing to kill mice at an intravenous dose of 20 mug/g body weight. The sequence of the first 25 residues out of the total of 65, was determined using the automatic sequenator. The remainder of the sequence was derived with the aid of tryptic and chymotryptic peptides. The sequence showed the unusual feature of having 65 amino acid residues including 10 half-cystine residues.