Quantitative analysis of blood cells and inflammatory factors in wounds.

OBJECTIVE: The aim of this study was to quantify blood cells and inflammatory markers, involved in the healing process, in exudates from wounds in different healing phases, to assess these markers in order to identify the inflammatory phase of the wounds. METHOD: Patients who presented with postsurgical wounds, which closed by first and second intention, and those who presented with pressure ulcers (PUs), which were closed by second intention, were included in the study. RESULTS: We examined wounds from 37 patients and collected samples from 52 wounds in the inflammatory phase, 30 in the proliferative phase and 29 in the maturation phase. The number of neutrophils and platelets in the exudate collected from wounds in the inflammatory phase was significantly higher (p<0.001), while the number of lymphocytes, was significantly lower in exudate from wounds in the inflammatory phase (p<0.001). Wound c-reactive protein (CRP) and immunoglobulin G (IgG) levels were higher in the inflammatory group (p<0.001). We found a significantly positive correlation between CRP levels and the percentage of neutrophils and monocytes (r=0.346, p=0.004; r=0.293, p=0.015), and a significantly negative correlation between CRP levels and the percentage of lymphocytes (r=-0.503, p<0.001). A stepwise logistic regression analysis was used to identify an optimal combination of these biomarkers. The optimal biomarker combinations were neutrophils + monocytes + platelets + IgG + CRP, with an area under the curve (AUC) of 0.981 [confidence interval (CI) 95%: 0.955-1.000, p<0.001] for the diagnosis of wounds in the inflammatory phase. The optimal cutpoint yielded 96.9 % sensitivity and 94.6 % specificity. The biomarker combination predicted the inflammatory phase and was superior to individual biomarkers. CONCLUSION: Our findings suggest that the combination of the markers, percentage of neutrophils and monocytes, platelets, CRP and IgG levels could be useful prognostic indicators of the inflammatory phase.

Sox2 functionally interacts with ßAPP, the ßAPP intracellular domain and ADAM10 at a transcriptional level in human cells.

Sox2 (SRY (Sex-determining region Y)-related high mobility group (HMG) box 2) is a transcription factor that serves key roles in controlling the balance between stem cells maintenance and commitment to differentiated lineages throughout the lifetime. Importantly, Sox2 deficiency results in early embryonic lethality whereas the down-regulation of Sox2 expression triggers neurodegeneration in the adult mouse brain. Moreover, Sox2 is decreased in the brain of Alzheimer's disease (AD) patients and co localizes with the ß-amyloid precursor protein (ßAPP) in stem cells. Here we report the existence of functional interactions between Sox2 and ßAPP, the ßAPP intracellular domain AICD50 and the α-secretase ADAM10 in human cells. We first show, as observed in embryonic stem cells, that ßAPP overexpression in HEK293 cells results in an increase of Sox2 immunoreactivity and we further establish the transcriptional nature of this pathway. Moreover, overexpression of the pro-apoptotic C-terminal ßAPP-derived AICD50 metabolite leads to the down-regulation of Sox2 transcription whereas the pharmacological inhibition of endogenous AICD production increases Sox2 expression in both HEK293 and SH-SY5Y cell lines. In addition, we demonstrate that Sox2 is a potent activator of the non amyloidogenic processing of ßAPP as shown by the Sox2-dependent augmentation of ADAM10 catalytic activity, immunoreactivity, promoter transactivation and mRNA levels with no modification of the activity and the expression of the ß-secretase BACE1. Finally, the fact that γ-secretase inhibition induces an increase of ADAM10 protein levels in SH-SY5Y cells further supports the occurrence of functional AICD/Sox2/ADAM10 interactions. Altogether, our study identifies and characterizes new functional cross-talks between Sox2 and proteins involved in AD, thereby adding support to the view that Sox2 likely behaves as a protective factor during the development of this neurodegenerative disease.

Publication trends in newspapers and scientific journals for SSRIs and suicidality: a systematic longitudinal study.

Background In the period 2003-2008, the regulatory authorities issued several warnings restricting the use of selective serotonin re-uptake inhibitors (SSRIs) in paediatrics, in reaction to safety concerns regarding the risk of suicidality. In this study, the SSRIs and suicidality controversy serves as a template to analyse the long-term publication trends regarding the benefit/risk profile of medications. The aim is to ascertain differences (in terms of numbers, categories and timing) between negative and positive newspaper and journal articles on SSRIs and suicidality and to ascertain correlations between changes in the reports and regulatory warnings. Methods A systematic review of scientific articles (Embase) and the Netherlands (NL) and the UK newspapers (LexisNexis) was performed between 2000 and 2010. Categorisation was done by 'effect' (related treatment effect), 'type of article' and 'age group'. The articles' positive-to-negative effect ratio was determined. Differences in distribution of effect categories were analysed across sources, type of article and age group using the Mann-Whitney (two subgroups) or Kruskal-Wallis test (three or more). Findings In total, 1141 articles were categorised: 352 scientific, 224 Dutch and 565 British newspaper articles. Scientific articles were predominantly on research and were positive, whereas newspaper articles were negative (ratios=3.50-scientific, 0.69-NL and 0.94-UK; p<0.001). Articles on paediatrics were less positive in scientific journals and more negative in newspapers (ratios=2.29-scientific, 0.26-NL and 0.20-UK; p<0.001), while articles on adults were positive overall (ratios=10.0-scientific, 1.06-NL and 1.70-UK; p<0.001). In addition, negative-effect reporting trends were exacerbated following regulatory warnings and were generally opinion articles, both in scientific journals and in newspapers (2003/2004 and after 2007). Interpretation The authors found a positive publication tendency inherent in journal research articles. This apparent positive publication bias present in scientific journals, however, does not seem to prevent the dissemination of 'bad' news about medications. The negative tendency present in Dutch and British newspapers was perceivable in the paediatrics group and during the warnings, indicating that national news media have informed the public about this international drug safety controversy on time.

Galactomannan from Caesalpinia spinosa induces phenotypic and functional maturation of human dendritic cells.

Plant polysaccharides present an interesting potential as immunomodulators, particularly in the induction of antitumoral responses, principally because of their molecular complexity and low in vivo toxicity. Activation of dendritic cells (DCs) could improve antitumoral responses usually diminished in cancer patients, and natural adjuvants provide a possibility of inducing this activation. Herein, we investigated the immunomodulatory activity of a neutral plant polysaccharide Galactomannan on human monocyte-derived DCs (MDDC). MDDCs were stimulated with Galactomannan (GLM) from Caesalpinia spinosa and both phenotypic and functional activities were assessed by flow cytometry and real-time PCR. The phagocytic ability of MDDCs was determined by using E-coli pHrodo particles and induction of T-lymphocyte allostimulation was determined after T-cell staining with carboxyfluorescein succinimidyl ester (CFSE). In MDDCs, purified Galactomannan induced phenotypic maturation revealed by increased expression of CD83, CD86, CD206, and HLA-DR. Functional experiments showed the loss of particulate antigen uptake in Galactomannan-stimulated DCs and increased alloantigen presentation capacity. Finally, Galactomannan increased protein and mRNA levels of pro-inflammatory cytokines including IL-1ß, IL-6, IL-8, IL-12p70, and TNF-α. These data reveal that Galactomannan obtained from Caesalpinia spinosa promotes effective activation of MDDCs. This adjuvant-like activity may have therapeutic applications in clinical settings where immune responses need boosting.

[Prognostic value of the sTREM-1 plasma values in patients with sepsis: a cohort study]. / Valor pronóstico de los niveles plasmáticos de sTREM-1 en pacientes con sepsis: un estudio de cohortes.

OBJECTIVE: To evaluate the association between plasma levels of soluble Triggering Receptor Expressed on Myeloid Cells-1 (sTREM-1) and mortality of patients with sepsis. DESIGN: Prospective cohort study. SETTING: Two general Intensive Care Units. PATIENTS: Patients with sepsis in whom sTREM-1 plasma levels were determined daily in the first 3 days of their presentation. VARIABLES OF INTEREST: Mortality at 28 days. RESULTS: We analyzed 121 patients (23% severe sepsis, 44% septic shock, 33% non-severe sepsis). Mortality at 28 days was 24.8%. The initial sTREM-1 levels were slightly higher in nonsurvivors than in survivors (median 366.9 versus 266.5 pg/ml, p=0.2668). An increase in sTREM-1 levels higher than 90 pg/ml within the first 3 days (delta-TREM) was associated with an excess of mortality (hazard ratio [HR] 2.68, p=0.0047), with a sensitivity of 47% and a specificity of 78%. This excess of mortality disappeared after adjusting for severity by Cox analysis (adjusted HR 1.07, p=0.8665). CONCLUSIONS: The increase in the levels of sTREM-1 during the first 3 days of evolution is associated with an excess of mortality in critically ill patients with sepsis. This is explained by the greater initial severity of these patients. The discriminative capacity of this finding is insufficient to be clinically useful.

Seroepidemiology of Toxoplasma gondii infection in pregnant women in rural Durango, Mexico.

The epidemiology of Toxoplasma gondii infection in pregnant women in rural Mexico is largely unknown. The seroepidemiology of T. gondii infection in 439 pregnant women from 9 communities in rural Durango State, Mexico was investigated. Using commercial enzyme-linked immunoassays, sera were tested for T. gondii IgG, IgM, and avidity antibodies. Prevalences of T. gondii IgG antibodies in the communities varied from 0% to 20%. Overall, 36 (8.2%) of the 439 women had IgG T. gondii antibodies. Ten (2.3%) women had also T. gondii IgM antibodies; IgG avidity was high in all IgM-positive women, suggesting chronic infection. None of the women, however, had delivered a known T. gondii-infected child. The seroprevalence was significantly higher (P < 0.05) in women from low socio-economic conditions (14%) than in those with higher socio-economic status (6.6%). Multivariate analysis showed that T. gondii infection was associated with soil floors at home (adjusted OR = 2.89; 95% CI: 1.12-7.49). This is the first epidemiological study of T. gondii infection in pregnant women in rural Mexico.

Structural insights into the design of inhibitors for the L1 metallo-beta-lactamase from Stenotrophomonas maltophilia.

One mechanism by which bacteria can escape the action of beta-lactam antibiotics is the production of metallo-beta-lactamases. Inhibition of these enzymes should restore the action of these widely used antibiotics. The tetrameric enzyme L1 from Stenotrophomonas maltophilia was used as a model system to determine a series of high-resolution crystal structures of apo, mono and bi-metal substituted proteins as well as protein-inhibitor complexes. Unexpectedly, although the apo structure revealed only few significant structural differences from the holo structure, some inhibitors were shown to induce amino acid side-chain rotations in the tightly packed active site. Moreover, one inhibitor employs a new binding mode in order to interact with the di-zinc center. This structural information could prove essential in the process of elucidation of the mode of interaction between a putative lead compound and metallo-beta-lactamases, one of the main steps in structure-based drug design.

High pressure liquid chormatography determination of the concentration and integrity of L-thyroxine in free T4 stock solution

Characterization studies were designed to evaluate the concentration and integrity of the L-thyroxine (T4) molecule (3,5,3',5'-tetraiodothyronine) in the free T4 stock solution (FT4SS) (code 99544). The determination of the concentration of T4 in FT4SS is critical to ensure that the free T4 calibrators and controls are manufactured with the least number of adjustments possible. The most significant conclusions drawn from these characterization studies are the following: (1) An accurate and sensitive HPLC method has been developed to measure the T4 concentration in FT4SS. The root cause of the failure of FT4SS to pass retest/ review is the presence of an unknown T4 degradation product with significantly higher molar extinction coefficient at 230 nm than T4 itself. The L-thyroxine concentration reference comparison spectrophotometric test with the current 43 to 58 ug/ml specification range (as per scp.99544, ed. 13A) is adequate to monitor the generation of the unknown T4 degradation product. The characterized T4 degradation product is not 3,5,3'-triiodo-thyronine (T3) and it is suspected that the identity of the degradation product is reverse T3 (3,3',5'-triiodothyronine). The use of sodium l-thyroxine pentahydrate (Na- T4-5H2O) as the equivalent of T4 (free base) is adequate provided that an excess of 15over the desired amount of T4 is weighed.

Radio-guided surgery improves outcome of therapeutic excision in non-palpable invasive breast cancer.

Intratumoral injection of a radiocolloid for lymphatic mapping enables the therapeutic excision of clinically occult breast cancer with the aid of a gamma-ray detection probe. The aim of this study was to determine the success rate of radio-guided tumour excision in addition to a guide wire and to identify factors predicting clear margins. Sixty-five consecutive patients underwent radio-guided tumour excision after intratumoral injection of 99mTc-nanocolloid guided by ultrasound or stereotaxis. A localization wire was inserted after scintigraphy had been performed (group 1). The results were compared with retrospective data from 67 consecutive patients who underwent therapeutic wire-directed excision alone (group 2). Factors predicting clear margins (> or = 1 mm) were determined in a logistic regression model. Adequate margins were obtained in 83% of group 1 and in 64% of group 2 (P = 0.014). The invasive component was incompletely excised in two patients in group 1 and in 14 patients in group 2. Further surgery was performed in four patients in group 1 and in 14 patients in group 2. Factors predictive of clear margins were decreasing pathological tumour diameter (P = 0.035), increasing weight of the specimen (P = 0.046), absence of microcalcifications (P = 0.004) and absence of carcinoma in situ component (P = 0.024). Radio-guided excision was an independent predictor of complete excision of the invasive component (P = 0.012). The application of radio-guided surgery combined with wire localization seems to improve the outcome of therapeutic excision of non-palpable invasive breast cancer compared with wire-directed excision alone.

Immature granulocyte detection by the SE-9000 haematology analyser during pregnancy.

The objective of this study was to determine the nature of the alarm for immature granulocytes appearing in haemograms from pregnant women, as detected by the immature cell information channel (IMI) of the SE-9000 automated haematology analyser. Of all tests run on pregnant women in a 4-month period (n = 698), the first 100 haemograms with immature granulocyte alarms (14.33%) were collected. Each of these samples was then stained with Wright-Giemsa stain. The following variables were also analysed: age of the mother, trimester and days of gestation, type of delivery, weight and sex of the baby, and Apgar score. Most pregnant women were in the third trimester of gestation (82%) when an alarm was noted on the IMI channel. Of the patients, 62% had normal deliveries. The most frequent complication was obstructed delivery (23%). Mean percentages by microscopic counts of band cells, metamyelocytes, and myelocytes were 2.99, 0.45, and 0.19%, respectively. There was a statistically significant correlation for all cell types between the SE-9000 and the manual count method. No association was observed between the presence of immature granulocytes and the clinical variables analysed. The SE-9000 analyser shows high sensitivity in the IMI channel for detection of immature forms.

JLK isocoumarin inhibitors: selective gamma-secretase inhibitors that do not interfere with notch pathway in vitro or in vivo.

gamma-Secretase activity is involved in the generation of Abeta and therefore likely contributes to the pathology of Alzheimer's disease. Blocking this activity was seen as a major therapeutic target to slow down or arrest Abeta-related AD progression. This strategy seemed more doubtful when it was established that gamma-secretase also targets other substrates including Notch, a particularly important transmembrane protein involved in vital functions, at both embryonic and adulthood stages. We have described previously new non-peptidic inhibitors able to selectively inhibit Abeta cellular production in vitro without altering Notch pathway. We show here that in vivo, these inhibitors do not alter the Notch pathway responsible for somitogenesis in the zebrafish embryo. In addition, we document further the selectivity of JLK inhibitors by showing that, unlike other described gamma-secretase inhibitors, these agents do not affect E-cadherin processing. Finally, we establish that JLKs do not inhibit beta-site APP cleaving enzymes (BACE) 1 and BACE2, alpha-secretase, the proteasome, and GSK3beta kinase. Altogether, JLK inhibitors are the sole agents to date that are able to prevent Abeta production without triggering unwanted cleavages of other proteins.

Tetrahedral aminopeptidase: a novel large protease complex from archaea.

A dodecameric protease complex with a tetrahedral shape (TET) was isolated from Haloarcula marismortui, a salt-loving archaeon. The 42 kDa monomers in the complex are homologous to metal-binding, bacterial aminopeptidases. TET has a broad aminopeptidase activity and can process peptides of up to 30-35 amino acids in length. TET has a central cavity that is accessible through four narrow channels (<17 A wide) and through four wider channels (21 A wide). This architecture is different from that of all the proteolytic complexes described to date that are made up by rings or barrels with a single central channel and only two openings.

Maintenance of transient chaos using a neural-network-assisted feedback control.

A stable period-3 orbit in the parametric vicinity of a chaotic attractor is destabilized using two distinct feedback strategies. This results in the inception and subsequent maintenance of the otherwise short-lived chaotic transients. Both the techniques employed are based on the exclusion of trajectories from the near vicinity of the open loop stable period-3 attractor; the first relies on the traditional proportional feedback method while the second one includes a predictive term enabling delimitation of exclusion zones for the system dynamics. The implementation of these strategies involves construction of appropriate reference models in the form of an artificial-neural-network approximator.

Solution structure of the squash trypsin inhibitor MCoTI-II. A new family for cyclic knottins.

The "knottin" fold is a stable cysteine-rich scaffold, in which one disulfide crosses the macrocycle made by two other disulfides and the connecting backbone segments. This scaffold is found in several protein families with no evolutionary relationships. In the past few years, several homologous peptides from the Rubiaceae and Violaceae families were shown to define a new structural family based on macrocyclic knottin fold. We recently isolated from Momordica cochinchinensis seeds the first known macrocyclic squash trypsin inhibitors. These compounds are the first members of a new family of cyclic knottins. In this paper, we present NMR structural studies of one of them, MCoTI-II, and of a beta-Asp rearranged form, MCoTI-IIb. Both compounds display similar and well-defined conformations. These cyclic squash inhibitors share a similar conformation with noncyclic squash inhibitors such as CPTI-II, and it is postulated that the main effect of the cyclization is a reduced sensitivity to exo-proteases. On the contrary, clear differences were detected with the three-dimensional structures of other known cyclic knottins, i.e., kalata B1 or circulin A. The two-disulfide cystine-stabilized beta-sheet motif [Heitz et al. (1999) Biochemistry 38, 10615-10625] is conserved in the two families, whereas in the C-to-N linker, one disulfide bridge and one loop are differently located. The molecular surface of MCoTI-II is almost entirely charged in contrast to circulin A that displays a well-marked amphiphilic character. These differences might explain why the isolated macrocyclic squash inhibitors from M. cochinchinensis display no significant antibacterial activity, whereas circulins and kalata B1 do.

Functional determinants of the Epstein-Barr virus protease.

Herpesvirus proteases are essential for the production of progeny virus. They cleave the assembly protein that fills the immature capsid in order to make place for the viral DNA. The recombinant protease of the human gamma-herpesvirus Epstein-Barr virus (EBV) was expressed in Escherichia coli and purified. Circular dichroism indicated that the protein was properly folded with a secondary structure content similar to that of other herpesvirus proteases. Gel filtration and sedimentation analysis indicated a fast monomer-dimer equilibrium of the protease with a K(d) of about 60 microM. This value was not influenced by glycerol but was lowered to 1.7 microM in the presence of 0.5 M sodium citrate. We also developed an HPLC-based enzymatic assay using a 20 amino acid residue synthetic peptide substrate derived from one of the viral target sequences for the protease. We found that conditions that stabilised the dimer also led to a higher enzymatic activity. Through sequential deletion of amino acid residues from either side of the cleavage site, the minimal peptide substrate for the protease was determined as P5-P2'. This minimal sequence is shorter than that for other herpesvirus proteases. The implications of our findings are discussed with reference to the viral life-cycle. These results are the first ever published on the EBV protease and represent a first step towards the development of protease inhibitors.

Structural biology of C1: dissection of a complex molecular machinery.

The classical pathway of complement is initiated by the C1 complex, a multimolecular protease comprising a recognition subunit (C1q) and two modular serine proteases (C1r and C1s) associated as a Ca2+-dependent tetramer (C1s-C1r-C1r-C1s). Early studies have allowed identification of specialized functional domains in these proteins and have led to low-resolution models of the C1 complex. The objective of current studies is to gain deeper insights into the structure of C1, and the strategy used for this purpose mainly consists of dissecting the C1 components into modular fragments, in order to solve their three-dimensional structure and establish the structural correlates of their function. The aim of this article is to provide an overview of the structural and functional information generated by this approach, with particular emphasis on the domains involved in the assembly, the recognition function, and the highly specific proteolytic properties of C1.

Comparison of preference for rizatriptan 10-mg wafer versus sumatriptan 50-mg tablet in migraine.

Rizatriptan (MAXALT, a registered trademark of Merck & Co. Inc.) is a selective 5-HT(1B/1D) receptor agonist with rapid oral absorption and early onset of action in the acute treatment of migraine. This randomized, open-label, crossover outpatient study assessed the preference of 481 patients for rizatriptan 10-mg rapidly disintegrating tablets versus sumatriptan (IMIGRAN, a registered trademark of GlaxoWellcome PLC) 50-mg tablets in the treatment of a single migraine attack with each therapy. Almost twice as many patients preferred rizatriptan 10-mg rapidly disintegrating tablet to sumatriptan 50-mg tablet (64.3 vs. 35.7%, p < or = 0.001). Faster relief of headache pain was the most important reason for the preference, cited by 46.9% of patients preferring rizatriptan and 43.4% of patients who preferred sumatriptan. Headache relief at 2 h was 75.9% with rizatriptan and 66.6% with sumatriptan (p < or = 0.001), with rizatriptan being superior to sumatriptan within 30 min of dosing. Fifty-five percent of patients were pain free 2 h after rizatriptan, compared with 42.1% treated with sumatriptan (p < or = 0.001), rizatriptan being superior within 1 h of treatment. Forty-one percent of patients taking rizatriptan were pain free at 2 h and had no recurrence or need for additional medication, compared to 32.3% of patients on sumatriptan. Rizatriptan was also superior to sumatriptan in terms of the proportions of patients with no nausea, phonophobia or photophobia, and patients with normal function 2 h after treatment intake (p < 0.05). More patients were (completely, very or somewhat) satisfied 2 h after treatment with rizatriptan (73.3%) than 2 h after treatment with sumatriptan (59.0%) (p < or = 0.001). Additionally, 2 h after the dose, more patients found rizatriptan to be very convenient, convenient or somewhat convenient (87.2%) than they did sumatriptan (76.3%) (p < or = 0.001). Both active treatments were well tolerated. The most common side effects with rizatriptan and sumatriptan were nausea (6.6 and 6.9% of patients, respectively), dizziness (6.1 and 5.8%) and somnolence (7.4 and 6.7%).

Squash trypsin inhibitors from Momordica cochinchinensis exhibit an atypical macrocyclic structure.

Three trypsin inhibitors (TIs), from the seeds of the squash Momordica cochinchinensis (MCo), have been isolated and purified using gel filtration, ion exchange chromatography, and reverse-phase HPLC. Their sequences could be determined only after proteolytic cleavages. In the case of MCoTI-I and -II, it was shown that their polypeptide backbones are cyclic, a structure that has never been described in squash TIs. They contain 34 amino acid residues with 3 disulfide bridges and measured molecular masses of 3453.0 and 3480.7, respectively. They are the largest known macrocyclic peptides containing disulfide bridges. Their sequences show strong homology to other squash TIs, suggesting a similar three-dimensional structure and an analogous mechanism of action. A model of MCoTI-II was constructed by analogy to the crystal structure of the complex between bovine trypsin and CMTI-I, indicating that the linker connecting the two termini is flexible and does not impose significant geometrical constraints. This flexibility allows an Asp-Gly peptide bond rearrangement to occur in this region, giving rise to two isoforms of MCoTI-II. Although the importance of cyclization is not clear, it might confer increased stability and resistance to proteolysis. A minor species, MCoTI-III, was also characterized as containing 30 amino acid residues with a molecular mass of 3379.6. This component possesses a linear backbone with a blocked N-terminus. MCoTIs represent interesting candidates for drug design, either by changing their specificity of inhibition or by using their structure as natural scaffolds bearing new binding activities.

Grafting an RGD motif onto an epidermal growth factor-like module: chemical synthesis and functional characterization of the chimeric molecule.

A novel protein was engineered by inserting the GRGDS motif of fibronectin within the 14-residue loop of the EGF-like module from human complement protease C1r. The resulting chimeric EGF-RGD module (52 residues, three disulfide bridges) was assembled by automated solid-phase synthesis using the t-Boc strategy. Using reduced/oxidized glutathione, the EGF-RGD module was folded as efficiently as the natural C1r-EGF module, resulting in formation of the appropriate disulfide bridge pattern as shown by mass spectrometry and N-terminal sequence analyses of thermolytic fragments. Circular dichroism and NMR measurements provided further indication that introduction of the GRGDS motif had no significant effect on the folding. Using Chinese Hamster Ovary (CHO) cells bearing the integrin receptors specific for fibronectin and vitronectin, EGF-RGD was shown to induce cell adhesion via the introduced GRGDS motif. Cell binding was inhibited specifically and efficiently by the synthetic peptide GRGDSP and by fibronectin, and to a much lesser extent by vitronectin, whereas the monoclonal antibody PB1 directed to the alpha5 subunit of alpha5beta1 integrin had no effect. The ability of EGF-RGD to trigger significant cell spreading and intracellular signaling was also demonstrated using immunofluorescence and confocal microscopy.

Mapping of the interaction between the immunodominant loop of the ectodomain of HIV-1 gp41 and human complement protein C1q.

The human immunodeficiency virus type 1 transmembrane envelope glycoprotein gp41 has been previously shown to activate the C1 complex of human complement through direct interaction with its C1q subunit. The major interaction site has been located within the gp41 immunodominant region (residues 590-620), and a synthetic peptide overlapping residues 601-613 of gp41 (sequence GIWGCSGKLICTT) was shown to inhibit binding of gp41 to C1q in vitro (Thielens, N.M., Bally, I.M., Ebenbichler, C.F., Dierich, M.P. & Arlaud, G.J. (1993) J. Immunol. 151, 6583-6592). The ectodomain of gp41 (s-gp41) was secreted from the methylotrophic yeast Pichia pastoris and purified by immunoaffinity chromatography. Enzymatic deglycosylation of the recombinant s-gp41 was necessary to allow its in vitro interaction with C1q. A solid-phase competition assay was used to monitor the effect of mutant peptides derived from segment 601-613 of gp41 on the binding of deglycosylated s-gp41 to C1q. Whereas mutation of Ser606 had no effect, replacement of Ile602, Trp603, Lys608, Leu609 and Ile610 by Ala abolished the ability of the resulting peptides to inhibit binding of s-gp41 to C1q, suggesting that these residues participate in the interaction between gp41 and C1q. These findings are discussed in the light of a structural model of the immunodominant loop of gp41. It is proposed that the recognition of gp41 by C1q is driven by hydrophobic interactions, and that the sites of gp41 responsible for interaction with gp120 and C1q partly overlap.