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PubMed2003

Chronic infection and coronary artery disease.

On a variety of fronts, chronic infection has been found to be significantly associated with the development of atherosclerosis and the clinical complications of unstable angina, myocardial infarction, and stroke. For the most part, these relationships are still just associations. Failure to confirm initial reports of serologic associations also has been common. Specific causative relationships on par with that determined between H pylori and peptic ulcer disease have not yet been established. Potential mechanisms whereby chronic infections may play a role in atherogenesis are myriad. In the case of C pneumoniae, the effect may result from direct vessel wall colonization that may damage the vessel either directly or indirectly by initiating immunologic responses. In other cases the effect may simply be that of enhancing the pre-existing chronic inflammatory response of the body to standard risk factors such as hyperlipidemia. Even though the infectious agent may not directly infect the vessel wall, it may perform its critical role from afar. Chronic infection might also influence pre-existing plaque by enhancing T-cell activation or other inflammatory responses that may participate in the destabilization of the intimal cap. Hence chronic infection may play a role either in the initiation, progression, or the destabilization of atherosclerotic plaques. The infectious agents with the most evidence to support an etiologic role in atherosclerosis include C pneumoniae and cytomegalovirus. Evidence is mounting for a variety of other potential agents including other herpes viruses, influenza, other specific bacteria (such as M pneumoniae), and chronic infections with common bacterial agents (periodontal disease, chronic bronchitis, and chronic urinary tract infection, among others) [191]. Future studies are expected to elucidate further the pathophysiologic relationship between chronic infection and atherosclerosis and to evaluate further the potential of a variety of treatment approaches, including antibiotics.

Bacterial Infections↗
PubMed1999

Characterization and processing of prostate specific antigen (hK3) and human glandular kallikrein (hK2) secreted by LNCaP cells.

Prostate specific antigen (PSA, hK3) in serum is predominantly complexed to alpha-1-antichymotrypsin (ACT), but a minor fraction remains in a free form despite the very large excess of serine protease inhibitors and alpha-2-macroglobulin. The fraction of free to total PSA is significantly lower in prostate cancer (CaP) compared to benign prostatic hyperplasia (BPH) which provides improved discrimination of these conditions. The molecular nature of free PSA in the circulation and the reason for its varying concentration in malignant and benign conditions is currently not known. The objective of the present investigation was to study the secretion of PSA and human glandular kallikrein 2 (hK2) by the LNCaP prostate cancer cell line, and to purify and characterize both proteins. LNCaP PSA was thoroughly characterized by immunological characterization, SDS-PAGE, isoelectric focusing, gel filtration, aminoterminal sequencing, reverse-phase chromatography, mass spectrometry and enzymatic activity measurements. LNCAP cells produced approximately equal amounts of zymogen (proPSA) and the one-chain mature form of PSA, whereas there was no evidence for the secretion of any internally cleaved forms. LNCaP cells secreted hK2 into the growth medium at about 3-5% of the amount of PSA. One-chain, mature PSA and hK2 obtained when LNCaP cells were grown in the presence of fetal bovine serum, had no enzymatic activity, but were active when the cells were grown in the absence of serum. Using enzymatically active recombinant hK2, it was possible to activate proPSA secreted by LNCaP cells. ProPSA formed two bands with high isoelectric points (8.2 and 8.4), which disappeared when proPSA was converted to mature PSA with hK2. Cancerous cells produce the zymogen forms of PSA, which by their isoelectric pI points seem to be found in serum of prostate cancer patients, but not BPH patients. Mature, one-chain PSA is inactive in the presence of serum. These findings may be highly relevant for the understanding of the generation of free and complexed PSA in the circulation.

Journal Article↗
PubMed1997

Immunologic reactivity on one year follow-up of subjects without allergy to Hymenoptera stings.

We studied Hymenoptera stings in 72 pest-control operators without any previous systemic reactions to Hymenoptera stings, and investigated their venom-specific IgE levels in serial specimens collected over one year. At the initial evaluation, venom-specific IgE was present in 25 (34.7%) of 72 pest-control operators, and venom-specific IgE titer significantly decreased as the time interval from the last sting increased (p < 0.001). In most cases, venom-specific IgE disappeared less than 3 years after the last sting. On the other hand, the ratio of subjects with positive CAP for venom-specific IgE was significantly increased with an elevation of total serum IgE level (p < 0.001). After the one year follow-up, venom-specific IgE titer in the 25 subjects with positive CAP decreased significantly (p = 0.026). Total serum IgE level modified the decline significantly (p = 0.011), but the time interval from the last sting did not. In elevated total IgE level (>250 IU/ml), the decline of venom-specific IgE tended to be slow.

Adult↗
PubMed2004

Increased numbers of B-1 cells and enhanced responses against TI-2 antigen in mice lacking APS, an adaptor molecule containing PH and SH2 domains.

APS (adaptor molecule containing PH and SH2 domains) is an intracellular adaptor protein that forms an adaptor family along with Lnk and SH2-B. While experiments using cultured cell lines have demonstrated that APS is phosphorylated in response to various stimuli, its in vivo functions remain unclear. We attempted to determine the physiological roles of APS by generating APS-deficient (APS(-/-)) mice. APS(-/-) mice were viable and fertile and showed no abnormalities or growth retardation. Immunologically, APS(-/-) mice showed normal development and distribution of lymphocytes and myeloid cells, except for increased numbers of B-1 cells in the peritoneal cavity. APS(-/-) mice exhibited an enhanced humoral immune response against trinitrophenol-Ficoll, a thymus-independent type 2 antigen, while APS(-/-) B-2 cells exhibited normal proliferative responses and tyrosine phosphorylation of intracellular proteins upon B-cell receptor (BCR) cross-linking. APS colocalized with filamentous actin (F-actin) accumulated during the capping of BCRs in APS-transgenic B cells. After BCR stimulation, F-actin contents were lower in APS(-/-) B-1 cells than in wild-type B-1 cells. Our results indicate that APS might have a novel regulatory role in actin reorganization and control of B-1 cell compartment size.

Actins↗
PubMed1981

Early changes in concanavalin A-stimulated lymphocytes detected by the fluorescent probe N-phenyl-1-naphthylamine.

The hydrophobic fluorescent cell-membrane probe N-phenyl-1-naphthylamine (NPN) is a useful investigative tool for studies of early lymphocyte activation. NPN-labelled mouse thymus cells incubated with 5 micrograms/ml concanavalin A (Con A) for 30 min at 37 degrees C gave a reproducible increase in mean cell-fluorescence intensity measured by microfluorimetry on 100 single cells. The dose-response curve was similar to that obtained by 3H-thymidine assay. Increased fluorescence was not observed in the presence of 10 mM alpha-methyl mannoside, 5 mM sodium azide, 10(-5) M cytochalasin B, or Ca2+-free culture medium. However, incubation with 10(-5) M colchicine did not alter the probe response. Fluorescence change was also shown by spleen cells from a normal mouse but not from an athymic mouse, indicating T cell dependence of the response. Comparison with other lectins showed that increased fluorescence followed incubation with phytohaemagglutinin, and the non-mitogenic wheat germ lectin, but there was no change with succinyl-Con A, and decreased fluorescence with pokeweek mitogen. Use of fluorescent-labelled lectins showed that the NPN fluorescence change did not correlate with surface receptor patching and capping. Increased phospholipid-fatty acid turnover and subsequent increased membrane fluidity with alteration of molecular polarity are suggested as likely explanations of increased NPN fluorescence.

1-Naphthylamine↗
PubMed1984

Reduction in the antigenicity of whey proteins by heat treatment: a possible strategy for producing a hypoallergenic infant milk formula.

Residual antigenic protein in heat-denatured cow's milk whey and in two commercial infant milk formulas was determined using enzyme-linked immunosorbent assays specific for beta-lactoglobulin, alpha-lactalbumin, bovine serum albumin, bovine IgG1 and alpha-casein. This immunochemical assessment of antigenicity was related to the capacity of the preparations to sensitize immunologically when fed to guinea-pigs for 2 weeks. Antibody production was measured and the susceptibility of the animals to systemic anaphylaxis was assessed by injecting them intravenously with heated or unheated milk proteins. Whey protein that had been heated at 100 degrees or 115 degrees for 30 min was extensively denatured and, in contrast to pasteurized whey, failed to sensitize guinea-pigs for anaphylaxis. Antibody production was undetected or very low. The proteins in SMA powder and SMA Gold Cap liquid concentrate were less denatured and animals given these formulas prepared according to the maker's instructions produced relatively high levels of antibodies to beta-lactoglobulin and alpha-casein and a majority developed anaphylaxis when injected intravenously with these products. As well as failing to sensitize, whey that had received severe heat treatment did not, in most cases, elicit anaphylaxis when injected into animals that had been sensitized with unheated milk. Discrimination between antibodies of the IgG1 and IgG2 subclasses specific for beta-lactoglobulin showed that IgG1, the principal anaphylactic antibody in guinea-pigs, was preferentially depressed in animals drinking heat-denatured milk preparations. The results suggest that heat denaturation of whey protein may be a logical and simple strategy for producing a hypoallergenic baby milk. Nevertheless, the value of experiments in guinea-pigs for predicting results in man is uncertain and the proposal awaits assessment in clinical trials.

Anaphylaxis↗
PubMed1997

Characterization of the promoter region of the rat testis-specific histone H1t gene.

Histone H1t is synthesized only in male germ cells during the late pachytene stage of meiosis and is retained in spermatids until the nucleus elongates. Transgenic experiments suggest that spermatocyte-directing sequences lie within 140 base pairs of the cap site. To study the mechanism of this specificity we compared the DNase I footprints made on the immediate promoter regions of H1t and H1d (a typical somatic H1) by testis and liver extracts and observed both common and differentially protected regions. The common footprints of H1t included an Sp1 consensus (GC box 1) and a CCAAT motif. Electrophoretic mobility shift assays (EMSA) identified ubiquitous binding factors for GC box 1 and a binding factor for the CCAAT element that we identified immunologically as H1TF2. H1t-specific footprints occurred over the palindrome CCTAGG and a GC-rich sequence downstream of the TATA box (GC box 2). EMSA analysis of the palindrome identified testis-specific as well as ubiquitous binding factors. UV irradiation of a palindrome-binding reaction generated a cross-linked doublet of about 50 kDa from both testis and liver. Protein factors that bound to the GC box 2 sequence were similar from testis and liver, and GC box 1 and an Sp1 consensus competed for them. In vitro transcription directed by H1t occurred at comparable levels in testis and liver extracts. The importance of both GC box 1 and CCAAT elements was demonstrated by deletion analysis and by oligonucleotide competition. No dependence on the H1t palindrome was observed for in vitro transcription.

Animals↗
PubMed1989

Binding of plasma membrane glycoproteins to the cytoskeleton during patching and capping is consistent with an entropy-enhancement model.

Concentrations of concanavalin A that induced patching and capping of cell surface receptors on Dictyostelium discoideum also induce binding of the receptors to the cortical cytoskeleton, which was isolated by density-gradient centrifugation. The receptors were solubilized by deoxycholate, purified by affinity chromatography, and used to determine whether the receptors bound directly to the cytoskeletal protein, actin. As the concentration of actin was increased, many of the receptors became bound to purified filamentous rabbit muscle actin, even in the absence of concanavalin A. As in the ligation-induced binding of receptors to the cortical cytoskeleton in cells, concanavalin A induced much stronger binding of the purified receptors to filamentous actin. The results were consistent with a previously stated hypothesis that induction of receptor binding to the cytoskeleton during their patching and capping is driven by clustering the receptors, which reduces their translational entropy and by doing so enhances their avidity for the cytoskeleton.

Actins↗
PubMed2002

Manifold significance of serum eosinophil cationic protein in asthmatic children.

Asthma is the result of complex interaction between different cells, mediators and nervous system that leads to an inflammatory response accompanied by increased bronchial hyperactivity. Its clinical manifestations include recurrent cough, wheezing and difficult breathing. The purpose of this study was to establish the possibility of diagnosing inflammation in asthmatic patients based on the assessment of serum eosinophil cationic protein (ECP), and of following the efficacy of asthmatic treatment by the levels of inflammation mediators. In a prospective study, 134 children aged 1 to 18 (mean 8) years underwent serum ECP assessment. Experimental group included 87 patients with asthma, 56 boys and 31 girls, mean age 9.1 (range 2-17) years. Control group included patients with recurrent non-allergic disorders, 27 boys and 20 girls aged 1-16 (mean 6.1) years. Serum ECP was assessed using the Pharmacia CAP system ECP-FEIA method, i.e. fluoroimmunoassay test for quantitative assessment of serum ECP levels. Serum values of ECP were significantly higher in asthmatics than in controls (p = 0.001). Our results showed that increased levels of serum ECP to significantly correlate with increased eosinophil (p = 0.018) and immunoglobulin E (p = 0.003) levels. Increased ECP levels reflect the degree of inflammation and correlate with the clinical picture severity in asthmatic patients. Assessment of serum ECP levels can reveal eosinophilic activity, and indirectly detect immunologic inflammation in asthmatics. It is possible to follow the dynamics of immunologic inflammation during the course of treatment as well as treatment efficacy.

Adolescent↗
PubMed1987

DNP-phycobiliproteins, fluorescent antigens to study dynamic properties of antigen-IgE-receptor complexes on RBL-2H3 rat mast cells.

In RBL-2H3 rat mucosal mast cells, the crosslinking of cell-surface IgE-receptor complexes by multivalent antigens initiates a sequence of responses leading to degranulation. We have developed a family of dinitrophenol (DNP)-conjugated fluorescent antigens to study dynamic membrane events associated with these responses. Lysyl groups on the phycobiliproteins, B-phycoerythrin and C-phycocyanin, were labelled with DNP, yielding fluorescent conjugates that cause the release of [3H]serotonin from anti-DNP-IgE-primed RBL-2H3 cells. The binding of these antigens to IgE-receptor complexes was observed by fluorescence microscopy and quantified by flow cytometry. Incubation with 1 microgram/ml DNP42-B-phycoerythrin stimulates maximum degranulation from IgE-saturated cells. Under these conditions, approximately 26 X 10(3) molecules of DNP42-B-phycoerythrin are bound per cell at equilibrium. The rate and extent of antigen binding and of antigen-stimulated mediator release decrease in parallel as the concentration and DNP:protein ratio of the fluorescent conjugates is reduced. Secretion stops immediately when the nonfluorescent monovalent antigen, DNP-lysine, is added to degranulating cell suspensions. DNP-lysine also displaces surface-bound antigen when added during the first minutes after multivalent antigen. However, the ability of DNP-lysine to displace surface-bound DNP42-B-phycoerythrin from IgE-receptor complexes decreases progressively with time. Treatment with dihydrocytochalasin B and several analogs that prevent antigen-stimulated F-actin assembly enhances secretion and delays the transition of antigen to its DNP-lysine-resistant form. Cytochalasin treatment also permits the long-range movement of antigen into surface caps.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2004

Opposing effects of aluminum on inward-rectifier potassium currents in bean root-tip protoplasts.

Inward currents in root cap protoplasts of the aluminum-tolerant cultivar, Dade, of Phaseolus vulgaris L. were investigated using the whole-cell patch-clamp technique. The properties of these currents were similar to those seen in inward rectifying K+ channels in other plant tissues. Replacing bath K+ with Na+ nearly abolished the observed currents. Higher bath K+ concentrations increased inward currents. AlCl3 in pH 4.7 bath solutions caused inward K+ currents to activate more rapidly and at more positive voltages when compared with AlCl3 free solutions. In 10 microM AlCl3 the activated inward K+ currents were significantly larger than in the AlCl3-free solution at all voltages except at the most negative voltage of -174 mV and the least negative of -74 mV. In contrast, in 80 microM Al3+, when hyperpolarizing voltages were most negative, the inward K+ currents were inhibited relative to the currents in 10 microM AlCl3. Enhancement of inward K+ currents by AlCl3 is consistent with Al3+ binding to the external surface of the root cap protoplast, decreasing the surface charge, thus causing the channels to sense a more negative membrane potential. Inhibition of inward K+ currents with higher AlCl3 concentrations and more negative voltages is consistent with Al3+ block of K+ channels.

Aluminum↗
PubMed1990

Large anaplastic cell Ki-1 positive malignant lymphoma with peculiar endocytotic vacuoles.

Unusual intracytoplasmic inclusions are occasionally seen in some variants of malignant lymphoma. We report here a case of large anaplastic cell malignant lymphoma with peculiar vacuoles of probable endocytotic origin. Immunological findings demonstrated the characteristics of activated cells typical of a large anaplastic cell Ki-1 positive lymphoma. The tumour cells exhibited a phenotype of peripheral helper-inducer T-cells. The intracytoplasmic vacuoles were positive with the T surface marker antibodies. Ultrastructurally, these inclusions were closely related to the microvesicle-containing vacuoles reported in signet ring cell lymphomas of B or T cell lineage. The mechanism of cytoplasmic vacuole formation is discussed. An endocytotic origin is possible. The resemblance to the "capping" phenomenon in small lymphocytes is stressed.

Adult↗
PubMed2000

IgE binding to almond proteins in two CAP-FEIA-negative patients with allergic symptoms to almond as compared to three CAP-FEIA-false-positive subjects.

BACKGROUND: Allergy to almonds has been frequently reported, but data on the identification of the almond allergens, as well as on the reliability of the methods for in vitro detection of specific IgE for these allergens, are scant. This study aimed to identify the almond allergens and to evaluate the reliability of the CAP-FEIA as the standard system for detection of almond-specific IgE with clinical significance. METHODS: Immunoblotting performed with an almond-protein extract was carried out on the sera of five patients who had previously been tested by the CAP-FEIA system; two of these patients had tested negative with the CAP-FEIA system but suffered life-threatening laryngeal edema after eating almonds, whereas the other three subjects, who had tested positive with CAP-FEIA, did not present any symptoms subsequent to almond ingestion. RESULTS: The sera of the two symptomatic CAP-FEIA-negative patients had IgE that bound only to a 37-kDa protein in immunoblotting. On the contrary, the sera of the three asymptomatic subjects all showed IgE binding to two almond proteins of 62 and 50 kDa, corresponding to the glycosylated components of the extract. CONCLUSIONS: The results here presented suggest that, at least for the examined subjects, the positivity to almond, as measured with a standard laboratory method, is due to the presence of the 62/50-kDa glycoproteins with little or no immunologic significance, and not to the binding to the 37-kDa polypeptide, which appears to be a true almond allergen.

Adult↗
PubMed1991

Alterations in distribution of surface and intracellular antigens during epididymal maturation of rat spermatozoa.

The surface membrane of mammalian spermatozoa is known to undergo considerable conformational and organizational changes during epididymal maturation. However, much less is known about remodelling of intracellular membranes. In this communication we have used specific immunological markers to study the behavior of several antigens both on and within rat spermatozoa as they mature in the epididymis. Four monoclonal antibodies (McAbs) designated 5B1, 1B5, 2D6, and 1B6 were used to probe testicular and caput and cauda epididymal spermatozoa by indirect immunofluorescence and immunogold labeling techniques. None of the McAbs bound to testicular spermatozoa; in all cases, they became reactive only on spermatozoa which had reached the caput epididymis. McAb 5B1 was restricted to the outer acrosomal membrane (OAM) of the acrosomal cap domain. The epitope first appeared on antigen(s) with molecular mass (Mr) of approximately 200 kDa in immature spermatozoa, but later in mature spermatozoa the antigen(s) had Mr of approximately 160 kDa. The antigen(s) recognized by 1B5 McAb on the other hand was initially distributed over the OAM of the entire acrosomal domain (cap + equatorial segment), but during maturation it became progressively more restricted in area until in cauda spermatozoa only the anterior tip of the OAM bound the McAb. McAb 2D6 also bound to the entire OAM and acrosomal contents of caput spermatozoa, but, unlike 5B1 and 1B5 McAbs, reactivity was transient. That is, staining was first detected in caput spermatozoa but then disappeared in corpus and cauda spermatozoa. In contrast to all of the above, 1B6 McAb bound to the surface membrane overlying the entire head domain of caput spermatozoa, but during maturation it became restricted to the postacrosomal domain. These results indicate that, in addition to remodeling of the surface membrane during epididymal maturation, extensive processing of intracellular membrane antigens also takes place and that it is very active within the acrosome. The nature of these intracellular processing events remains to be elucidated, but they may have important consequences for membrane fusion and cell recognition phenomena during fertilization.

Animals↗
PubMed1979

Ultrastructural localization of guinea pig spermatozoal autoantigens on germinal cells by immunoperoxidase techniques.

Three guinea pig spermatozoal autoantigens S, P and T, each one able to induce autoimmune aspermatogenic orchiepididymitis and autoantibodies, were ultrastructurally localized in male germinal cells by immunoperoxidase techniques. Both living and prefixed sectioned cell preparations were treated and examined. Fab antibody fragments were used to study intracellular antigens (whole antibodies were inefficient). Water-soluble S and P autoantigens were found in acrosomal structures in the same sites: proacrosomal and acrosomal granules of the young spermatids, on the head caps of spermatids and acrosomal cap of spermatozoa, along the inner and outer acrosomal membranes and in the outer zone of the acrosomal matrix of the same cells. S was never found in the inner zone of spermatid or spermatozoa acrosomes, while P was present in this inner zone, but only of young spermatids. Water-insoluble T autoantigen was found on the plasmalemma and outer acrosomal membranes of spermatids and spermatozoa, inside the spermatid cytoplasm and, sometimes, on the inner acrosomal membrane of young spermatids. The specificity of the immunological localization for each antigen was confirmed by testing with specific antisera following absorption with homologous and heterologous antigens. No other testicular cell type (including Sertoli cells per se) was found to bear S, P or T autoantigens. When use was made of autoimmune sera obtained through autologous whole spermatozoa, the observed staining was an additive combination of what was observed when using the preceding three immune sera, anti-S, anti-P and anti-T.

Animals↗
PubMed1995

Immunomodulation by LFA3TIP, an LFA-3/IgG1 fusion protein: cell line dependent glycosylation effects on pharmacokinetics and pharmacodynamic markers.

LFA3TIP, a fusion protein comprised of the first extracellular domain of LFA-3 fused to the hinge, CH2, and CH3 domains of human IgG1 inhibits responses of human and non-human primate T cells in vitro. In seeking to optimize the expression efficiency to prepare large quantities of LFA3TIP for primate studies, the protein was produced in both the CHO (Chinese hamster ovary) and murine NS-0 myeloma cell lines. Although LFA3TIP derived from these cell lines performs identically in vitro in CD2 receptor binding and T cell assays, examination of a pharmacodynamic marker-the reduction in CD2+ lymphocyte numbers-following the administration of equal doses of NS-0 or CHO derived LFA3TIP to baboons, suggested that the effect of the NS-0 derived material was less sustained. Pharmacokinetic analysis of the materials in baboons and mice shows that LFA3TIP produced by NS-0 cells is rapidly cleared from circulation relative to the product derived from CHO cells. The disparate clearance profiles correlate with distinct glycosylation patterns, with LFA3TIP derived from NS-0 cells being less extensively sialylated than that from CHO cells due in part to alpha-galactosyl capping of selected lactosamine moieties in the N-linked glycans of NS-0 derived LFA3TIP. Moreover, enzymatic desialylation of CHO derived LFA3TIP results in a glycoprotein with an evanescent serum profile when administered to mice and baboons. These results correlate the extent of N-acetylneuraminic acid capping with the clearance rates of LFA3TIP derived from the two distinct cell lines, and underscore the importance of evaluating glycosylation dependent PK parameters when choosing production cell lines for recombinant immunotherapeutics.

Adjuvants, Immunologic↗
PubMed1998

Bacterial infections and atherosclerosis.

On a variety of fronts, chronic bacterial infection is being found to be significantly associated with the development of atherosclerosis and the clinical complications of unstable angina, myocardial infarction, and stroke. Although for the most part, these are still just associations, and specific causative relationships on the par with that determined for Helicobacter pylori and peptic ulcer disease have not been determined. Further studies may well lead to a similar conclusion about these potential mechanisms whereby chronic infections may play a role in atherosclerosis on myocardial infarction. As in the case of Chlamydia pneumoniae, the affect may result from direct vessel wall colonization and infection. This local infection may either react directly on the vessel wall or indirectly through its initiation of a number of immunologic responses. In other cases, the influence of chronic infection on the progression of atherosclerosis may be related to an indirect affect of enhancing the chronic inflammatory response of the body. Even though the infectious agent may not directly infect the vessel wall it may have a critical affect acting from afar. There is a potential that chronic bacterial infection may aggravate pre-existing plaque by enhancing T cell activation as well as other inflammatory responses that may participate in the destabilization of the intimal cap resulting in plaque rupture, progression to acute ischemic syndromes, and ultimate enlargement of the atherosclerotic plaque. Consequently, chronic bacterial infection may play a role in the initiation, the progression, or the destabilization of atherosclerotic plaques. Further studies that are presently ongoing and planned for the near future are expected to not only further elucidate the pathophysiology related with the association between chronic bacterial infection and atherosclerosis but also evaluate whether antibiotic treatment may result in clinical benefit to the patient.

Arteriosclerosis↗
PubMed1991

Radixin is a novel member of the band 4.1 family.

Radixin is an actin barbed-end capping protein which is highly concentrated in the undercoat of the cell-to-cell adherens junction and the cleavage furrow in the interphase and mitotic phase, respectively (Tsukita, Sa., Y. Hieda, and Sh. Tsukita. 1989 a.J. Cell Biol. 108:2369-2382; Sato, N., S. Yonemura, T. Obinata, Sa. Tsukita, and Sh. Tsukita. 1991. J. Cell Biol. 113:321-330). To further understand the structure and functions of the radixin molecule, we isolated and sequenced the cDNA clones encoding mouse radixin. Direct peptide sequencing of radixin and immunological analysis with antiserum to a fusion protein were performed to confirm that the protein encoded by these clones is identical to radixin. The composite cDNA is 4,241 nucleotides long and codes for a 583-amino acid polypeptide with a calculated molecular mass of 68.5 kD. Sequence analysis has demonstrated that mouse radixin shares 75.3% identity with human ezrin, which was reported to be a member of the band 4.1 family. We then isolated the cDNA encoding mouse ezrin. Sequence analysis and Northern blot analysis revealed that radixin and ezrin are similar but distinct (74.9% identity), leading us to conclude that radixin is a novel member of the band 4.1 family. In erythrocytes the band 4.1 protein acts as a key protein in the association of short actin filaments with a plasma membrane protein (glycophorin), together with spectrin. Therefore, the sequence similarity between radixin and band 4.1 protein described in this study favors the idea that radixin plays a crucial role in the association of the barbed ends of actin filaments with the plasma membrane in the cell-to-cell adherens junction and the cleavage furrow.

Amino Acid Sequence↗