Suppressor of cytokine signaling-3 preferentially binds to the SHP-2-binding site on the shared cytokine receptor subunit gp130

Suppressor of cytokine signaling-3 (SOCS-3) is one member of a family of intracellular inhibitors of signaling pathways initiated by cytokines that use, among others, the common receptor subunit gp130. The SH2 domain of SOCS-3 has been shown to be essential for this inhibitory activity, and we have used a quantitative binding analysis of SOCS-3 to synthetic phosphopeptides to map the potential sites of interaction of SOCS-3 with different components of the gp130 signaling pathway. The only high-affinity ligand found corresponded to the region of gp130 centered around phosphotyrosine-757 (pY757), previously shown to be a docking site for the tyrosine phosphatase SHP-2. By contrast, phosphopeptides corresponding to other regions within gp130, Janus kinase, or signal transducer and activator of transcription proteins bound to SOCS-3 with weak or undetectable affinity. The significance of pY757 in gp130 as a biologically relevant SOCS-3 docking site was investigated by using transfected 293T fibroblasts. Although SOCS-3 inhibited signaling in cells transfected with a chimeric receptor containing the wild-type gp130 intracellular domain, inhibition was considerably impaired for a receptor carrying a Y-->F point mutation at residue 757. Taken together, these data suggest that the mechanism by which SOCS-3 inhibits the gp130 signaling pathway depends on recruitment to the phosphorylated gp130 receptor, and that some of the negative regulatory roles previously attributed to the phosphatase SHP-2 might in fact be caused by the action of SOCS-3.

Levels of interleukin-1 beta, -8, and -10 and RANTES in gingival crevicular fluid and cell populations in adult periodontitis patients and the effect of periodontal treatment

BACKGROUND

Various cytokines have been identified at sites of chronic inflammation such as periodontitis. Cytokines are synthesized in response to bacteria and their products, inducing and maintaining an inflammatory response in the periodontium. The purpose of the present study was to investigate the involvement of interleukin-1 beta (IL-1 beta), IL-8, and IL-10 and RANTES (regulated on activation, normally T cell expressed and secreted) and the cell populations associated with the immune response in destructive periodontitis, as well as the effect of periodontal therapy on cytokine levels in gingival crevicular fluid (GCF).

METHODS

Data were obtained from 12 patients with moderate to advanced periodontitis and 6 healthy controls. Patients presenting at least 2 sites with > or =2 mm clinical attachment loss were included in the destructive periodontitis group. After monitoring for 4 months, only 6 patients showed destructive periodontitis and GCF samples and soft tissues biopsies were collected from these patients. GCF samples and biopsies were collected both from active (12 CGF samples and 6 biopsies) and inactive (12 CGF samples and 6 biopsies) sites. The comparison with healthy controls was carried out by collecting GCF samples from 6 healthy volunteers (12 samples) and biopsies during the surgical removal of wisdom teeth. In periodontal patients, clinical data and GCF samples were obtained prior to periodontal treatment (72 samples) and 2 months after periodontal therapy (72 samples). GCF was collected using a paper strip; eluted and enzyme-linked immunoabsorbent assays (ELISA) were performed to determine cytokine levels. The inflammatory infiltrate was analyzed by immunohistochemistry of gingival biopsy samples with monoclonal antibodies against CD3, CD8, CD4, CD11c, and CD19 antigens.

RESULTS

Cellular components of the inflammatory infiltrate include B and T lymphocytes and monocyte/macrophages. Active sites contained a higher number of B lymphocytes and macrophages. IL-8 and IL-1 beta and RANTES in GCF were detected in the majority of sites from periodontal patients (100%, 94% and 87%, respectively); IL-10 was found in only 43%. IL-8 was the only cytokine detected in the GCF (75%) of the control group. Moreover, IL-1 beta levels were significantly higher in active sites versus inactive sites (P <0.05). IL-8 and IL-10 and RANTES were increased in active sites; however, differences were not significant (P>0.05). A positive correlation between the IL-8 and RANTES (r = 0.677, P<0.05) was observed in periodontitis patients. Periodontal therapy reduced the total amount of IL-1 beta, IL-8, and IL-10 and RANTES. Data showed a weak correlation between the clinical parameters and the total amount of cytokines in periodontitis.

CONCLUSIONS

These data suggest that the amount of crevicular IL-1 beta, IL-8, and IL-10 and RANTES is associated with periodontal status. Removal of the bacterial plaque reduces the antigenic stimuli and consequently could modulate the chemokines present in GCF. We propose that the dynamic interactions between cytokines, their production rates, and their quantity could represent factors controlling the induction, perpetuation, and collapse of the cytokine network present in the periodontal disease.

Transgenic expression of mouse proinsulin II prevents diabetes in nonobese diabetic mice

IDDM in humans and in nonobese diabetic (NOD) mice is a T-cell-dependent autoimmune disease in which the beta-cells of the pancreatic islets are destroyed. Several putative beta-cell autoantigens have been identified, but insulin and its precursor, proinsulin, are the only ones that are beta-cell specific. (Pro)insulin may be a key autoantigen in IDDM. To address the role of proinsulin in the development of IDDM, we generated NOD mice transgenic for the mouse proinsulin II gene driven off a major histocompatibility complex (MHC) class II promoter to direct expression of the transgene to MHC class II bearing cells, including those in the thymus, with the aim of deleting proinsulin-reactive T-cells. The mononuclear cell infiltration of the islets (insulitis) is almost completely absent, and diabetes is prevented in these transgenic NOD mice. The mononuclear cell infiltration of the salivary glands (sialitis) and immune responses to ovalbumin (OVA) are not altered, indicating that the protective effect of the transgene is specific for islet pathology and not due to general immunosuppression. We conclude that autoimmunity to proinsulin plays a pivotal role in the development of IDDM.

Extracellular signal-regulated protein kinase signaling pathway negatively regulates the phenotypic and functional maturation of monocyte-derived human dendritic cells

Dendritic cells (DC) are highly specialized antigen-presenting cells that on activation by inflammatory stimuli (eg, tumor necrosis factor alpha [TNF-alpha] and interleukin-1beta [IL-1beta]) or infectious agents (eg, lipopolysaccharide [LPS]), mature and migrate into lymphoid organs. During maturation, DC acquire the capacity to prime and polarize resting naive T lymphocytes. Maturation of monocyte-derived DC (MDDC) is inhibited by the p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580. This study found that in the presence of the mitogen-activated protein kinase kinase 1-extracellular signal-regulated kinase (ERK) inhibitors PD98059 or U0126, TNF-alpha- and LPS-induced phenotypic and functional maturation is enhanced. ERK pathway inhibitors increased expression of major histocompatibility complex and costimulatory molecules; loss of mannose-receptor-mediated endocytic activity; nuclear factor-kappaB DNA-binding activity; release of IL-12 p40; and allogeneic T-cell proliferation induced by LPS or TNF-alpha. Moreover, PD98059 and U0126 enhanced LPS-triggered production of IL-12 p70. In agreement with the effect of ERK inhibitors, maturation of MDDC was delayed in the presence of serum, an effect that was reversed by U0126. These results indicate that the ERK and p38 MAPK signaling pathways differentially regulate maturation of MDDC and suggest that their relative levels of activation might modulate the initial commitment of naive T-helper (Th) cells toward Th1 or Th2 subsets. The findings also suggest that maturation of MDDC might be pharmacologically modified by altering the relative levels of activation of both intracellular signaling routes.

Requirement for alpha-CaMKII in experience-dependent plasticity of the barrel cortex

The mammalian sensory neocortex exhibits experience-dependent plasticity such that neurons modify their response properties according to changes in sensory experience. The synaptic plasticity mechanism of long-term potentiation requiring calcium-calmodulin-dependent kinase type II (CaMKII) could underlie experience-dependent plasticity. Plasticity in adult mice can be induced by changes in the patterns of tactile input to the barrel cortex. This response is strongly depressed in adult mice that lack the gene encoding alpha-CaMKII, although adolescent animals are unaffected. Thus, alpha-CaMKII is necessary either for the induction or for the expression of plasticity in adult mice.

Characterization of cellular infiltrate, detection of chemokine receptor CCR5 and interleukin-8 and RANTES chemokines in adult periodontitis

Leukocyte migration is essential for immune surveillance of tissues by focusing immune cells to sites of antigenic challenge. The control of leukocyte migration depends on the combined actions of adhesion molecules and a vast array of chemokines and their receptors. The purpose of the present study was to investigate the involvement of Interleukin-8 (IL-8), RANTES, the associated infiltrating cells and expression of CCR5 chemokine receptors in periodontitis; furthermore, the effect of periodontal therapy on these parameters was evaluated. Patients included in the study had moderate to advanced periodontal disease with at least 5-6 teeth with probing depth > 6 mm, attachment loss > or =3 mm and extensive radiographic bone loss. The inflammatory infiltrate was analyzed by immunohistochemistry in gingival biopsies obtained from subjects at the beginning of the study and 2 months after periodontal treatment. Gingival crevicular fluid (GCF) was collected for 30 seconds using periopaper strips, and chemokines were quantified by ELISA. The cellular components of the inflammatory infiltrate included B (CD19) and T (CD3, CD4+ and CD8+) lymphocytes and monocytes/macrophages (CD11c). CCR5 chemokine receptor expressing cells were exclusively found in periodontitis gingiva. IL-8 and RANTES were detected in the periodontitis group, obtaining a total amount of 212.5 pg and 42.0 pg, respectively. However, IL-8 was also detectable in the GCF of the healthy group (total amount of 44.8 pg). Periodontal therapy reduced the cell number in the infiltrate and the levels of IL-8 and RANTES, suggesting a relationship between these chemokines and periodontal status. We propose that the presence of these chemokines and the expression of chemokine receptors may represent a marker of lymphocyte subsets with the ability to migrate to inflammatory sites.

Fibronectin interaction with alpha4beta1 integrin prevents apoptosis in B cell chronic lymphocytic leukemia: correlation with Bcl-2 and Bax

B cell chronic lymphocytic leukemia (B-CLL) consists of the accumulation of malignant cells that apparently escape normal apoptotic regulation. We have studied the role of alpha4beta1 integrin/fibronectin interaction in preventing apoptosis of these cells in vitro. B cells from 16 patients showed constant expression of alpha4beta1 and little or no alpha5beta1. B-CLL cells cultured on fibronectin or two previously described fibronectin recombinant fragments (H89 and H0) which contain the ligands for alpha4beta1, consistently showed higher viability than control cells cultured on poly-lysine. The H89 fragment, containing the high affinity ligand CS-1, was the most efficient substrate with mean cell viability values of 72, 60 and 35% at days 2, 5 and 8 of culture, respectively. For control cells these values were 40, 27 and 15%, respectively. Parallel cell cycle analysis confirmed these results. The anti-apoptotic effect required direct contact with immobilized substrata since it was not observed when using B-CLL conditioned media alone or when clustering alpha4beta1 with specific mAbs in suspension. Quantitation of the apoptosis regulatory proteins Bcl-2 and Bax revealed that cells cultured on the H89 fragment showed high/moderate levels of Bcl-2 (with some interpatient variation) and low levels of Bax resulting in an elevated Bcl-2/Bax ratio. These results indicate that adhesion of B-CLL cells to fibronectin upregulate the Bcl-2/Bax ratio and this may contribute to the anti-apoptotic effect induced via alpha4beta1 integrin.

DNA immunization: induction of higher avidity antibody and effect of route on T cell cytotoxicity

Immunizations of mice with plasmid DNAs encoding ovalbumin (OVA), human Ig, and hen egg lysozyme were compared with doses of soluble protein (without adjuvant) that induced similar IgG responses. The route of immunization influenced the magnitude of the antibody (Ab) response in that intradermal (i.d.) injection elicited higher IgG Ab levels than i.m. injection in both DNA- and protein-immunized mice. Although total IgG levels were similar to soluble protein controls, the avidity of the anti-OVA Abs generated by DNA immunization were 100- and 1,000-fold higher via the i.m. or i.d. route, respectively. However, despite the generation of high-avidity Ab in DNA-immunized mice, germinal centers could not be detected in either DNA- or protein-immunized mice. Examination of the IgG subclass response showed that IgG2a was induced by i.m. DNA immunization, coinciding with elevated interferon gamma production, whereas a dominant and elevated IgG1 response, coinciding with detectable interleukin 4 production, was generated after i.d. immunization with DNA or soluble OVA and hen egg lysozyme but not human Ig protein. As expected, cytotoxic T cell (CTL) responses could be detected only after DNA immunization. I.d. immunization produced the strongest CTL responses early (2 weeks) but was similar to i.m. later. Therefore, DNA immunization can differ from protein immunization by its ability to induce rapid CTL responses and higher avidity Ab, both of which are advantageous for vaccination.

NAD(+) and axon degeneration revisited: Nmnat1 cannot substitute for Wld(S) to delay Wallerian degeneration

The slow Wallerian degeneration protein (Wld(S)), a fusion protein incorporating full-length nicotinamide mononucleotide adenylyltransferase 1 (Nmnat1), delays axon degeneration caused by injury, toxins and genetic mutation. Nmnat1 overexpression is reported to protect axons in vitro, but its effect in vivo and its potency remain unclear. We generated Nmnat1-overexpressing transgenic mice whose Nmnat activities closely match that of Wld(S) mice. Nmnat1 overexpression in five lines of transgenic mice failed to delay Wallerian degeneration in transected sciatic nerves in contrast to Wld(S) mice where nearly all axons were protected. Transected neurites in Nmnat1 transgenic dorsal root ganglion explant cultures also degenerated rapidly. The delay in vincristine-induced neurite degeneration following lentiviral overexpression of Nmnat1 was significantly less potent than for Wld(S), and lentiviral overexpressed enzyme-dead Wld(S) still displayed residual neurite protection. Thus, Nmnat1 is significantly weaker than Wld(S) at protecting axons against traumatic or toxic injury in vitro, and has no detectable effect in vivo. The full protective effect of Wld(S) requires more N-terminal sequences of the protein.

Prostaglandin E2 and the increase of intracellular cAMP inhibit the expression of interleukin 2 receptors in human T cells

We have analyzed the effect mediated by prostaglandin E2 (PGE2) and different reagents that increase intracellular cAMP on the expression of the p55 subunit (CD25) of interleukin 2 receptors (IL 2R), on the levels of CD25-specific mRNA and on the expression of high affinity IL 2R. In purified T cells, activated either by an anti-CD3 monoclonal antibody or phytohemagglutinin, the addition of PGE2 (10(-6) M), forskolin (5 X 10(-5) M), cholera toxin (0.2 microgram/ml) or dibutyryl cAMP (dBcAMP) (10(-4) M) decreased the cell surface expression of IL 2R by reducing (40%-78% inhibition) the proportions of CD25+ cells as well as the expression of high affinity IL 2R, detectable after 24 h. Furthermore, it was observed that PGE2 reduced the concentration of IL 2R-specific mRNA after a 6-h period of activation, indicating that its regulatory activity takes place at a pretranslational level. The addition of exogenous recombinant IL 2 only partially reversed the inhibition, thus suggesting that PGE2 and increased intracellular concentration of cAMP directly interfered with CD25 expression and that their effect could not be merely attributed to a lack of IL 2-dependent positive feedback. Cells cultured under the same conditions in the presence of phorbol myristate acetate, that activates protein kinase C, were refractory to the cAMP-mediated regulation. Finally, we demonstrate that both PGE2 and dBcAMP inhibit the generation of inositol metabolites after T cell activation, thus indicating that these reagents interfere with early signal transduction mechanisms which precede the synthesis of IL 2R.

The role of alpha-CaMKII autophosphorylation in neocortical experience-dependent plasticity

Calcium/calmodulin kinase type II (CaMKII) is a major postsynaptic density protein. CaMKII is postulated to act as a 'molecular switch', which, when triggered by a transient rise in calcium influx, becomes active for prolonged periods because of its ability to autophosphorylate. We studied experience-dependent plasticity in the barrel cortex of mice carrying a point mutation of the alpha-CaMKII gene (T286A), which abolishes this enzyme's ability to autophosphorylate. Plasticity was prevented in adult and adolescent mice homozygous for the mutation, but was normal in heterozygotes and wild-type littermates. These results provide evidence that the molecular switch hypothesis is valid for neocortical experience-dependent plasticity.

A second merozoite surface protein (MSP-4) of Plasmodium falciparum that contains an epidermal growth factor-like domain

Merozoite surface proteins of Plasmodium falciparum play a critical role in the invasion of human erythrocytes by the malaria parasite. Here we describe the identification of a novel protein with a molecular mass of 40 kDa that is found on the merozoite surface of P. falciparum. We call this protein merozoite surface protein 4 (MSP-4). Evidence for the surface location of MSP-4 includes (i) a staining pattern that is consistent with merozoite surface location in indirect immunofluorescent studies of cultured parasites, (ii) localization of MSP-4 in the detergent phase in Triton X-114 partitioning studies, and (iii) nucleotide sequencing studies which predict the presence of an N-terminal signal sequence and a hydrophobic C-terminal sequence in the protein. Immunoprecipitation studies of biosynthetically labelled parasites with [3H] myristic acid indicated that MSP-4 is anchored on the merozoite surface by a glycosylphosphatidylinositol moiety. Of considerable interest is the presence of a single epidermal growth factor-like domain at the C terminus of the MSP-4 protein, making it the second protein with such a structure to be found on the merozoite surface.

Expression, mutation and copy number analysis of platelet-derived growth factor receptor A (PDGFRA) and its ligand PDGFA in gliomas

BACKGROUND

Malignant gliomas are the most prevalent type of primary brain tumours but the therapeutic armamentarium for these tumours is limited. Platelet-derived growth factor (PDGF) signalling has been shown to be a key regulator of glioma development. Clinical trials evaluating the efficacy of anti-PDGFRA therapies on gliomas are ongoing. In this study, we intended to analyse the expression of PDGFA and its receptor PDGFRA, as well as the underlying genetic (mutations and amplification) mechanisms driving their expression in a large series of human gliomas.

METHODS

PDGFA and PDGFRA expression was evaluated by immunohistochemistry in a series of 160 gliomas of distinct World Health Organization (WHO) malignancy grade. PDGFRA-activating gene mutations (exons 12, 18 and 23) were assessed in a subset of 86 cases by PCR-single-strand conformational polymorphism (PCR-SSCP), followed by direct sequencing. PDGFRA gene amplification analysis was performed in 57 cases by quantitative real-time PCR (QPCR) and further validated in a subset of cases by chromogenic in situ hybridisation (CISH) and microarray-based comparative genomic hybridisation (aCGH).

RESULTS

PDGFA and PDGFRA expression was found in 81.2% (130 out of 160) and 29.6% (48 out of 160) of gliomas, respectively. Its expression was significantly correlated with histological type of the tumours; however, no significant association between the expression of the ligand and its receptor was observed. The absence of PDGFA expression was significantly associated with the age of patients and with poor prognosis. Although PDGFRA gene-activating mutations were not found, PDGFRA gene amplification was observed in 21.1% (12 out of 57) of gliomas. No association was found between the presence of PDGFRA gene amplification and expression, excepting for grade II diffuse astrocytomas.

CONCLUSION

The concurrent expression of PDGFA and PDGFRA in different subtypes of gliomas, reinforce the recognised significance of this signalling pathway in gliomas. PDGFRA gene amplification rather than gene mutation may be the underlying genetic mechanism driving PDGFRA overexpression in a portion of gliomas. Taken together, our results could provide in the future a molecular basis for PDGFRA-targeted therapies in gliomas.

Age-dependent decrease of synaptic plasticity in the neocortex of alphaCaMKII mutant mice

Synaptic long-term potentiation (LTP) and long-term depression (LTD) were studied in the visual cortex of mutant mice lacking alpha-calcium/calmodulin-dependent protein kinase II (alphaCaMKII). In adult mutants, little LTD or LTP could be elicited using standard conditioning protocols. However, substantial LTD and LTP were induced in 4- to 5-week-old mutants. Thus, the reduction in cortical plasticity in alphaCaMKII (-/-) mice is conditional, with the relevant condition being postnatal age.

Apoptosis in chronic adult periodontitis analyzed by in situ DNA breaks, electron microscopy, and immunohistochemistry

BACKGROUND

Apoptosis is an evolutionary form of physiological cell death. Previous studies suggest that apoptosis is involved in the pathogenesis of periodontal diseases. Therefore, we studied the apoptotic events in the gingival tissue of chronic adult periodontitis patients.

METHODS

Gingival tissue biopsies from 22 patients with chronic adult periodontitis and from 11 healthy controls were obtained. Criteria for patient inclusion in the periodontitis group were a minimum of 14 natural teeth, excluding third molars, with at least 10 posterior teeth; 5 to 6 sites with probing depth > or = 5 mm; attachment loss > or = 3 mm; and extensive radiographic bone loss. The control group included healthy subjects with no prior history of periodontal disease. Apoptosis was determined using the terminal TdT-mediated dUTP-biotin nick end labeling (TUNEL) technique; electron microscopic analysis; and expression of Caspase-3, Fas, FasL, Bcl-2, and p53 by immunohistochemistry.

RESULTS

TUNEL-positive cells and cells exhibiting chromatin condensation by electron microscopy were observed in the inflammatory infiltrate of biopsies obtained from periodontitis patients. Most of the TUNEL-positive cells belonged to neutrophil cell populations as they were stained with anti-myeloperoxidase. Positive staining for active-caspase 3, Fas, FasL, and p53 was only observed in the inflammatory infiltrate from periodontitis biopsies, whereas Bcl-2 cells were present in both periodontitis patients and healthy controls.

CONCLUSIONS

Our findings establish that apoptosis is induced in the periodontal tissue by host and microbial factors and support the hypothesis that apoptotic mechanisms could be implicated in the inflammatory process associated with gingival tissue destruction observed in adult periodontitis patients.

Molecular variation in a novel polymorphic antigen associated with Plasmodium falciparum merozoites

A cDNA clone encoding part of a novel polymorphic merozoite antigen from Plasmodium falciparum was isolated by screening a cDNA library with human immune serum from Papua New Guinea. Immunofluorescence microscopy and immunoblotting with affinity-purified antibodies recognized a highly polymorphic antigen, Ag956, present in schizonts and merozoites. Biosynthetic labeling and immunoprecipitation experiments demonstrated that Ag956 is proteolytically cleaved during merozoite maturation. The complete genomic sequence of Ag956 from the D10 clone of P. falciparum isolate FC27 encodes a secreted protein of calculated molecular mass 43,243 that is very hydrophilic and contains a region of unusual heptad repeats of the general structure AXXAXXX. This antigen has been named the secreted polymorphic antigen associated with merozoites (SPAM). The sequence of a second SPAM allele from the 3D7 clone of isolate NF54 reveals that the alanine heptad repeats and the hydrophilic C-terminal half of the protein are conserved. Variation among SPAM alleles is the result of deletions and amino acid substitutions in non-repetitive sequences within and flanking the alanine heptad-repeat domain. Heptad repeats in which the a and d position contain hydrophobic residues generate amphipathic alpha-helices which give rise to helical bundles or coiled-coil structures in proteins. Thus, SPAM is the first example of a P. falciparum antigen in which a repetitive sequence has features characteristic of a well-defined structural element.

Pesticides in Portuguese surface and ground waters

Pesticides used in Portuguese agricultural areas have been found in surface and ground waters. In the surface water collected in three river basins from 1983 to 1999, insecticides and herbicides were detected from the monitored pesticides, particularly atrazine, chlorfenvinphos (Z+E), alpha- and beta-endosulfan, lindane, molinate and simazine, reaching the maximum values, respectively, of 0.63, 31.6, 0.18 microg/L (alpha-endosulfan), 0.18 microg/L (beta-endosulfan), 0.24, 48 and 0.3 microg/L. In the ground water collected from the wells of seven agricultural areas from 1991 to 1998, several monitored herbicides were detected: alachlor, atrazine, metolachlor, metribuzine and simazine, reaching the maximum concentration values of 13, 30, 56, 1.4 and 0.4 microg/L, respectively. The herbicides more frequently detected were atrazine (64%), simazine (45%) and alachlor (25%). Other than these, the monitored pesticides can be present in Portuguese surface and ground waters. Therefore, to improve the analytical conditions, the use of multiresidue methods and automated techniques are desirable in future work.

Plasmodium falciparum: two antigens of similar size are located in different compartments of the rhoptry

Two previously described antigens, AMA-1 and QF3, which are located in the rhoptries of Plasmodium falciparum merozoites have polypeptides of similar relative molecular masses. On immunoblots, antibodies to both antigens recognized polypeptides of relative molecular mass 80,000 and 62,000 in all isolates tested. Two-dimensional electrophoresis showed that the isoelectric points of the two antigens were different. QF3 being more basic than AMA-1. AMA-1 was soluble in Triton X-114 whereas QF3 partitioned into the aqueous phase after temperature-dependent phase separation. In immunoelectron microscopic studies. QF3 was found in the body of the rhoptry whereas AMA-1 was consistently found in the neck of the rhoptry. Both antigens gave a punctate double-dot pattern in mature schizonts and merozoites when visualized by fluorescence microscopy, but AMA-1 antibodies also appeared to label the merozoite surface. QF3 was also detected in ring-infected erythrocytes whereas AMA-1 was not. Synthesis of both antigens was first observed in mature trophozoites and immature schizonts. Pulse-chase experiments showed that the Mr 80,000 polypeptide of the AMA-1 gene was subject to immediate processing to the Mr 62,000 product. This cleavage pattern was not stage specific. The Mr 80,000 polypeptide of QF3 was derived from a short-lived Mr 84,000 precursor polypeptide. Processing of the Mr 80,000 polypeptide to an Mr 62,000 polypeptide was restricted to the period of merozoite maturation and reinvasion. Hence AMA-1 and QF3 are different antigens with polypeptides of similar size but located in different compartments of the merozoite rhoptries.

Integral membrane protein located in the apical complex of Plasmodium falciparum

We describe the cloning of a novel antigen of Plasmodium falciparum which contains a hydrophobic domain typical of an integral membrane protein. This antigen is designated apical membrane antigen 1 because it appears to be located in the apical complex. Apical membrane antigen 1 appears to be transported to the merozoite surface near the time of schizont rupture.

Inhibition of nitric oxide synthase in experimental gram-negative sepsis

Nitric oxide (NO) has been proposed as a mediator of hypotension in septic shock. The aim of this study was to determine whether an inhibitor of NO production, NG-monomethyl-L-arginine (L-NMMA), was able to protect against death in two murine models of experimental gram-negative sepsis. L-NMMA (3-300 mg kg-1) did not improve survival in intravenous or intraperitoneal models of sepsis. Seven h after intravenous infection, L-NMMA (100 mg/kg-1) reduced serum nitrite plus nitrate levels (NO breakdown products) from 774 microM in control-treated animals to 282 microM in L-NMMA-treated animals (P < .001). This compared to a level of 103 microM in uninfected mice. L-NMMA produced little change in bacterial load following infection and did not increase hepatic damage, as measured by serum levels of ornithine carbamoyltransferase. Thus, while L-NMMA may reverse the hyporesponsiveness of peripheral circulation in sepsis, it was unable to prevent death in these models of gram-negative septic shock.

Preliminary assessment of the safety and immunogenicity of a new CTXPhi-negative, hemagglutinin/protease-defective El Tor strain as a cholera vaccine candidate

Vibrio cholerae 638 (El Tor, Ogawa), a new CTXPhi-negative hemagglutinin/protease-defective strain that is a cholera vaccine candidate, was examined for safety and immunogenicity in healthy adult volunteers. In a double-blind placebo-controlled study, no significant adverse reactions were observed in volunteers ingesting strain 638. Four volunteers of 42 who ingested strain 638 and 1 of 14 who received placebo experienced loose stools. The strain strongly colonized the human small bowel, as evidenced by its isolation from the stools of 37 of 42 volunteers. V. cholerae 638, at doses ranging from 4 x 10(7) to 2 x 10(9) vibrios, elicited significant serum vibriocidal antibody and anti-Ogawa immunoglobulin A antibody secreting cell responses.

p53 regulates the self-renewal and differentiation of neural precursors

During embryo neurogenesis, neurons that originate from stem cells located in the forebrain subventricular zone (SVZ) continuously migrate to the olfactory bulb (OB). However, other authors describe the occurrence of resident stem cells in the OB. In the present work we report that the absence of tumor suppressor protein p53 increases the number of neurosphere-forming cells and the proliferation of stem cells derived from 13.5-day embryo OB. Interestingly, differentiation of p53 knockout-derived neurospheres was biased toward neuronal precursors, suggesting a role for p53 in the differentiation process. Moreover, we demonstrate the relevance of p53 in maintaining chromosomal stability in response to genotoxic insult. Finally, our data show that neurosphere stem cells are highly resistant to long-term epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) deprivation in a p53-independent fashion, and they preserve their differentiation potential. Thus, these data demonstrate that p53 controls the proliferation, chromosomal stability and differentiation pattern of embryonic mouse olfactory bulb stem cells.

Characterization and gene sequence of the precursor of elafin, an elastase-specific inhibitor in bronchial secretions

Human bronchial mucous secretions have been shown to contain inhibitors of serine proteinases secreted by neutrophils. The role of these inhibitors is probably to control the enzymes secreted in the airways and in the lung interstitium. Three of these inhibitors have been identified and characterized: alpha 1-proteinase inhibitor, mucus proteinase inhibitor, and elafin. The elafin molecule, a 6.0 kD inhibitor of serine proteinases shows homology with mucus proteinase inhibitor. We recently isolated both molecules in bronchial secretions. In this report, we present evidence for the existence of a precursor of the elafin molecule. We have cloned and sequenced the gene for this precursor and show that it is composed of three exons. The coding information for a 117 amino acid precursor protein of elafin (inclusive of the signal peptide) is contained in the first two exons. This was confirmed at the mRNA and protein levels. By Northern Blot analysis we detected a 800 bp long product, and by immunoaffinity we detected in sputum and in cultured epithelial cell supernatant (NCI-H322 cell line) a 12 kD protein species cross-reacting with anti-elafin IgG. The finding of possible cross-linking function for the precursor in addition to its antiproteinase activity indicates a possible role for this molecule as a cross-linker agent in the extracellular matrix.