bluuebunny/crossref_metadata_2025 huggingface dataset:
Thyroid Dysfunction in Women with Systemic Sclerosis
Authors: MARASINI BIANCA , FERRARI PIER ALDA , SOLARO NADIA , SELMI CARLO
Published: October 2007

Abstract:  Hypothyroidism has been frequently reported in systemic sclerosis (SSc), but whether SSc itself increases the risk of thyroid dysfunction is still controversial. The aim of the present study was to determine whether routine thyroid function screening in SSc should be warranted. Serum levels of free triiodothyronine, free thyroxine, and thyroid‐stimulating hormone, and the presence of thyroid‐specific autoantibodies (antithyroid peroxidase and antithyreoglobulin) were measured in 79 women with SSc and 81 age‐matched women with osteoarthritis (OA) serving as controls. Hyperthyroidism was found in 2 of 79 (2.5%) SSc and in 4 of 81 (5%) OA cases. Hypothyroidism was found in 16 of 79 (20%) patients with SSc (subclinical in 14/16 cases) and in 9 of 81 (11%) patients with OA (subclinical in all cases; P= 0.131). Antithyreoglobulin antibodies were present in 14% versus 13% patients (SSc versus OA, P= NS), whereas antithyroid peroxidase antibodies were present in 23% versus 11% patients (SSc versus OA, P= 0.057). The risk of hypothyroidism was significantly higher in antithyroid peroxidase‐positive patients (P < 0.0001), irrespective of the primary diagnosis, and greater in women with OA (OR = 24.6, 95% CI 4.3–141.9, P < 0.0001) than SSc (OR = 4.2, 95% CI 1.2–14.3, P= 0.035). SSc is not independently associated with an increased risk of thyroid dysfunction, but antithyroid peroxidase antibodies may identify a subset of patients at risk of developing thyroid dysfunction.
The Immunology of Rheumatoid Arthritis
Authors: SCRIVO ROSSANA , DI FRANCO MANUELA , SPADARO ANTONIO , VALESINI GUIDO
Published: October 2007

Abstract:  Rheumatoid arthritis (RA) is represents the most common chronic inflammatory joint disease and is still a major medical challenge because of unsolved issues related to the etiologic and pathogenetic questions. Intensive research has been conducted over the last years that focused on the inappropriate activation of the immune system: although T cells have long been deemed to play a central role in the origin and propagation of joint inflammation, data accumulated so far have widened this perspective recognizing the contribution of other cells, as well as the major histocompatibility complex class II proteins and a composite set of costimulatory signals responsible for the production of proinflammatory cytokines and other soluble mediators implicated in tissue destruction typical of the disease. This paper will provide an insight into the immune system in RA, dissecting cellular and humoral aspects both in serum and in synovium of patients.
Accelerated Atherosclerosis in Rheumatoid Arthritis
Authors: SZEKANECZ ZOLTÁN , KEREKES GYÖRGY , DÉR HENRIETT , SÁNDOR ZSUZSA , SZABÓ ZOLTÁN , VÉGVÁRI ANIKÓ , SIMKOVICS ENIKÖ , SOÓS LILLA , SZENTPÉTERY ÁGNES , BESENYEI TIMEA , SZÜCS GABRIELLA , SZÁNTÓ SÁNDOR , TAMÁSI LÁSZLÓ , SZEGEDI GYULA , SHOENFELD YEHUDA , SOLTÉSZ PÁL
Published: October 2007

Abstract:  Cardiovascular disease is a leading cause of mortality in rheumatoid arthritis (RA). Endothelial dysfunction often precedes manifest atherosclerosis. Both traditional, Framingham risk factors and inflammation‐associated factors are involved in RA‐associated atherosclerosis. Among imaging techniques, the early determination of common carotid intima‐media thickness (ccIMT), flow‐mediated vasodilation (FMD), and nitroglycerine‐mediated vasodilation (NMD) may be useful to determine atherosclerosis and endothelial dysfunction. We and others found increased ccIMT and impaired FMD in RA patients. Among immunological and metabolic laboratory markers, anticyclic citrullinated peptide (anti‐CCP) antibodies, IgM rheumatoid factor, circulating immune complexes, pro‐inflammatory cytokines including tumor necrosis factor‐α (TNF‐α) and interleukin‐6 (IL‐6), Th0/Th1 T cells, homocysteine, dyslipidemia, decreased folate and vitamin B12 production, and impaired paraoxonase activity may all be involved in the development of vascular disease in RA. The early diagnosis of endothelial dysfunction and atherosclerosis, active immunosuppressive treatment, the use of drugs that control atherosclerosis, changes in sedentary lifestyle, and the close follow‐up of RA patients may help to minimize cardiovascular risk in these individuals.
Increased Production of the Soluble Tumor‐Associated Antigens CA19‐9, CA125, and CA15‐3 in Rheumatoid Arthritis
Authors: SZEKANECZ ÉVA , SÁNDOR ZSUZSA , ANTAL‐SZALMÁS PÉTER , SOÓS LILLA , LAKOS GABRIELLA , BESENYEI TIMEA , SZENTPÉTERY ÁGNES , SIMKOVICS ENIKÖ , SZÁNTÓ JÁNOS , KISS EMESE , KOCH ALISA E. , SZEKANECZ ZOLTÁN
Published: October 2007

Abstract:  Some tumor‐associated antigens (TAAs) are expressed on inflammatory cells. We previously detected carcinoembryonic antigen (CEA; CD66) in the rheumatoid (RA) synovium. The production of CEA, CA19‐9, CA125, and CA15.3, may be increased in patients with RA, scleroderma, lupus, and Sjögren's syndrome (SS). Some of these TAAs contain sialylated carbohydrate motifs and they are involved in tumor‐associated cell adhesion and metastasis. We assessed levels of TAAs in the sera of RA patients and healthy subjects. Serum TAA levels were correlated with disease markers including serum rheumatoid factor (RF), C‐reactive protein (CRP), and anti‐CCP antibody levels, DAS28, age disease duration. TAAs including CEA, CA15‐3, CA72‐4, CA125, and CA19‐9, and neuron‐specific enolase (NSE) were assessed by immunoassay in the sera of 75 patients with RA and 50 age‐ and sex‐matched healthy controls. Normal upper limits for these TAAs were 3.4 μg/L, 25 kU/L, 6.9 kU/L, 35 kU/L, 34 kU/L, and 16.3 μg/L, respectively. There were significantly more RA patients showing abnormally high levels of CA125 (10.8% versus 7.1%), CA19‐9 (8.1% versus 0%), and CA15‐3 (17.6% versus 14.3%) in comparison to controls (P < 0.05). The mean absolute serum levels of CA125 (23.9 ± 1.8 versus 16.8 ± 2.2 kU/L) and CA19‐9 (14.2 ± 1.2 versus 10.5 ± 1.6 kU/L) were also significantly higher in RA compared to controls (P < 0.05). Among RA patients, serum CEA showed significant correlation with RF (r= 0.270; P < 0.05). None of the assessed TAAs showed any correlation with CRP, anti‐CCP, DAS28, age or disease duration. The concentration of some TAAs may be elevated in the sera of patients with established RA in comparison to healthy subjects. CEA, CA19‐9, CA125, and CA15‐3 contain carbohydrate motifs and thus they may be involved in synovitis‐associated adhesive events. Furthermore, some TAAs, such as CEA, may also correlate with prognostic factors, such as serum RF levels.
Precocious Atherosclerosis in Rheumatoid Arthritis
Authors: GERLI ROBERTO , SHERER YANIV , BOCCI ELENA BARTOLONI , VAUDO GAETANO , MOSCATELLI SHEILA , SHOENFELD YEHUDA
Published: October 2007

Abstract:  The risk of cardiovascular (CV) disease increases in patients with rheumatoid arthritis (RA). This is due to a number of different triggers including traditional and disease‐related factors. Among established risk factors for CV disease, smoking may exert a more dangerous effect on arterial wall in RA than in the general population by a synergic effect with inflammatory processes of the disease. Although persistent inflammation and immune dysregulation of RA may contribute to favor other well‐known CV risk factors, such as dyslipidemia, it is now clear that the disease itself represents an independent risk factor for CV disease by the action of RA chronic inflammatory process as well as humoral and cell‐mediated immune mechanisms. There is evidence that CV risk is associated with severity and extension of the disease and it is of interest the fact that the presence of circulating anticyclic citrullinated peptide antibodies appears to be associated with stronger evidence of subclinical atherosclerosis in RA.
Preclinical Impairment of Coronary Flow Reserve in Patients with Rheumatoid Arthritis
Authors: ATZENI FABIOLA , SARZI‐PUTTINI PIERCARLO , DE BLASIO GIUSEPPE , DELFINO LUIGI , TOMASONI LIVIO , TURIEL MAURIZIO
Published: October 2007

Abstract:  Cardiovascular involvement in rheumatoid arthritis (RA) is common, although the true prevalence of cardiac abnormalities is difficult to measure, as much disease remains clinically silent. The pathogenesis of cardiac lesions in RA is related to the primary disorder of microcirculation with diffuse arteriolar and capillary lesions. Previous studies demonstrated that coronary flow reserve (CFR) is impaired in patients with connective tissue diseases (CTD). This review focuses on transthoracic Doppler echocardiography as a noninvasive method used to assess CFR in RA patients. CFR is early reduced in RA patients without clinical evidence of heart disease as a result of impaired microcirculation. CFR seems a useful technique able to follow‐up and to assess effects of new drugs on RA patients.
Cartilage Oligomeric Matrix Protein Level in Rheumatic Diseases
Authors: MOROZZI GABRIELLA , FABBRONI MARTA , BELLISAI FRANCESCA , PUCCI GABRIELLA , GALEAZZI MAURO
Published: October 2007

Abstract:  Cartilage oligomeric matrix protein (COMP) is a tissue‐specific noncollagenous protein that was first detected in the serum and the synovial fluid of patients suffering from rheumatic disorders, such as rheumatoid arthritis, reactive arthritis, juvenile chronic arthritis, and osteoarthritis. In this review, the authors consider serum COMP levels in different diseases and discuss their study of patients with rheumatoid arthritis treated with anti‐TNF‐α, to evaluate whether COMP is able to predict a rapid and sustained clinical response to these drugs. They observe that patients with high COMP levels have a lower ACR 70 response independently of the state of systemic inflammation, and conclude that COMP seems to have a pathogenetic role that is independent of the mechanisms regulating inflammatory processes.
Autoantibodies from Sjögren's Syndrome Trigger Apoptosis in Salivary Gland Cell Line
Authors: SISTO MARGHERITA , LISI SABRINA , LOFRUMENTO DARIO , D'AMORE MASSIMO , SCAGLIUSI PASQUALE , MITOLO VINCENZO
Published: October 2007

Abstract:  The presence of serum autoantibodies has been associated with Sjögren's syndrome (SS), an autoimmune rheumatic disease that targets salivary and lachrymal glands. The association of apoptosis with autoantibodies production seems to play a role in the pathogenesis of glandular damage. The best‐defined antibodies in SS are those reacting with the ribonucleoprotein antigens SS‐A (Ro) and SS‐B (La). Anti‐Ro antibodies are found in about 70–90%, and anti‐La in approximately the same frequency, of patients with primary SS. The objective of this work was to explore whether anti‐Ro and anti‐La autoantibodies purified from Sjögren IgG fractions are able to trigger apoptotic process in the human salivary gland cell line A‐253. Anti‐Ro and anti‐La autoantibodies were purified on protein G Sepharose affinity column and used for the A‐253 cell treatment. Apoptosis induced by autoantibodies was revealed by FACS analysis, and the active caspase‐3 and the cleaved caspase‐3 substrate poly (ADP‐ribose) polymerase (PARP) was demonstrated by colorimetric assay and Western blot. This report shows that anti‐Ro and anti‐La autoantibodies, but not healthy IgG, activate the caspase‐3 and determine the cleavage of PARP in A‐253 cells. Apoptosis triggered by Sjögren autoantibodies could be responsible for the impairment of the secretory function in the salivary glands.
The Influence of Sex Steroids on Sjögren's Syndrome
Authors: POROLA PAULIINA , LAINE MIKAEL , VIRKKI LIISA , PODUVAL PRASEET , KONTTINEN YRJÖ T.
Published: October 2007

Abstract:  Sjögren's syndrome is an autoimmune disease affecting the exocrine glands, most typically salivary and lacrimal glands. In Sjögren's syndrome, the acinar cells of these glands are damaged and destroyed, leading to diminished secretion of saliva and tear fluid. Accordingly, the current American‐European criteria of Sjögren's syndrome include xerostomia (dry mouth) and keratoconjunctivitis sicca (dry eyes). In addition to these sicca symptoms and signs, the diagnostic criteria require autoimmune features in the form of Sjögren's syndrome SS‐A and/or SS‐B autoantibodies and lymphocyte infiltrates in labial salivary glands. Majority of patients with Sjögren's syndrome are women and the diagnosis is usually done when they are 40–50 years old. The cause of Sjögren's syndrome is unknown, but taking into account the female dominance and the late onset, our hypothesis is that sex steroids play a key role in the etiology of Sjögren's syndrome. More specifically, we believe that the driving factor behind Sjögren's syndrome could be lack of androgens. It has been shown that patients with Sjögren's syndrome have low concentrations of circulating dehydroepiandrosterone sulfate (DHEA‐S) compared to age‐matched healthy controls. Our hypothesis is that patients with Sjögren's syndrome suffer from an insufficient local androgen effect in the exocrine target tissues of the disease because of low systemic levels and/or ineffective local intracrine handling of DHEA‐S prohormone. To further clarify the role of sex steroids and the eventual deficiency of androgens, salivary glands are studied using protein markers regulated by androgens or estrogens.
Cross‐Reactive Epitopes on β2‐Glycoprotein‐I and Saccharomyces cerevisiae in Patients with the Antiphospholipid Syndrome
Authors: KRAUSE I. , BLANK M. , CERVERA R. , FONT J. , MATTHIAS T. , PFEIFFER S. , WIES I. , FRASER A. , SHOENFELD Y.
Published: October 2007

Abstract:  Anti‐Saccharomyces cerevisiae antibodies (ASCA), directed against the phosphopeptidomannan (PPM) part of the cell wall of the yeast, have been identified as an important and specific serological marker for Crohn's disease. We evaluated the prevalence and properties of ASCA in APS patients. Thirty‐one out of 155 APS patients tested positive for ASCA (20.0%), compared to 5.0% in healthy controls (P < 0.05). The presence of ASCA was not associated with any specific manifestation of APS. The ASCA found to be the population of anti‐β2GPI antibodies (Abs). Affinity purified anti‐β2GPI from ASCA‐positive sera on a β2GPI column, bound specifically the PPM, as shown by direct binding and competition assays (95‐98%). The PPM inhibited differentially the anti‐β2GPI binding to β2GPI. Since the anti‐β2GPI anti‐PPM could bind only native form of β2GPI and not the recombinant form, we assume that these specific anti‐β2GPI subpopulations of Abs are directed to the glycosylated site of the molecule. In conclusion, a subpopulation of anti‐β2GPI is specific to the glycosylated site of the β2GPI molecule that cross‐reacts with PPM.
Pregnancies Complicated with Antiphospholipid Syndrome: The Pathogenic Mechanism of Antiphospholipid Antibodies
Authors: DI SIMONE NICOLETTA , LUIGI MERONI PIER , MARCO D'ASTA , FIORELLA DI NICUOLO , SILVIA D'IPPOLITO , CLARA D'ALESSIO MARIA , ALESSANDRO CARUSO
Published: October 2007

Abstract:  There are several possible mechanisms by which antiphospholipid antibodies (aPL) may have adverse effects on placental functions. Examination of placentas and first‐trimester decidua from antiphospholipid syndrome–complicated pregnancies has found little evidence of specific thrombotic placental pathology. It is now generally accepted that the clinically relevant aPL bind to proteins with affinity for phospholipids. The most important epitope for antiphospholipid syndrome–related aPL resides on β2‐glycoprotein‐I (β2GPI). aPL detected by anti‐β2GPI assays are associated with fetal loss. During differentiation to syncytium, trophoblasts express cell membrane anionic phospholipids that can bind β2GPI. Adhered β2GPI can be recognized by the antibodies that, once bound, interfere with trophoblast cell maturation, resulting in defective placentation. The improved outcome of pregnancies treated with heparin stimulated interest on the drug's mechanism of action. Several mechanisms could explain its beneficial effects in addition to a direct effect of heparin on the coagulation cascade. It might reduce the binding of aPL, inflammation by inhibiting complement activation, and might facilitate implantation. Further investigations are needed to better understand how aPL induce obstetric complications and to better clarify the functional role of heparin in the human placenta, leading to more successful therapeutic options.
C5a Receptor‐Deficient Mice Are Protected from Thrombophilia and Endothelial Cell Activation Induced by Some Antiphospholipid Antibodies
Authors: ROMAY‐PENABAD ZURINA , LIU X XIAOWEI , MONTIEL‐MANZANO GUADALUPE , De MARTÍNEZ ELIZABETH PAPALARDO , PIERANGELI SILVIA S.
Published: October 2007

Abstract:  Recent findings indicate that complement activation—involving specifically C3 and C5—contributes to antiphospholipid (aPL)‐mediated thrombosis. Two complement effector pathways are initiated by the cleavage of C5, C5a and C5b, which leads to the formation of the C5b‐9 membrane attack complex. To delineate and distinguish the role of C5a from the C5b‐9 membrane attack complex seeded by C5b, we examined the in vivo effects (thrombosis) of aPL on C5a receptor‐deficient (C5aR−/−) mice. C5aR−/− and C5aR+/+ mice were injected with IgM or with IgG from two different patients with APS (IgM‐APS or IgG‐APS) or with control IgM or IgG (IgM‐NHS or IgG‐NHS) twice. Complement fixing activity of the Ig fractions and anticardiolipin activity in the sera of the mice were determined by enzyme‐linked immunosorbent assay. Surgical procedures to study thrombus dynamics were performed. IgM‐APS but not IgG‐APS fixed C1q to cardiolipin‐coated plates. IgM‐APS significantly enhanced thrombus size in C5aR+/+ mice compared to C5aR+/+ mice treated with IgM‐NHS (3198 ± 2361 μm2 versus 585 ± 460 μm2). C5aR−/− mice treated with IgM‐APS showed a significant reduction in thrombi size as compared with C5aR+/+ mice (676 ± 690 μm2 versus 3198 ± 2361 μm2; P= 0.001). IgG‐APS enhanced thrombus formation significantly in C5aR+/+ when compared to IgG‐NHS‐treated mice (3507 ± 965 μm2 versus 1321 ± 798 μm2), and these effects were not altered in C5aR−/− mice (3400 ± 1681 μm2). The data indicate that C5aR−/− mice are protected from the thrombogenic effects of some aPL antibodies.
Epstein–Barr Virus and Cytomegalovirus in Autoimmune Diseases
Authors: BARZILAI O. , SHERER Y. , RAM M. , IZHAKY D. , ANAYA J.M. , SHOENFELD Y.
Published: October 2007

Abstract:  To date, it is believed that the origin of autoimmune diseases is one of a multifactorial background. A genetic predisposition, an immune system malfunction or even backfire, hormonal regulation, and environmental factors all play important roles in the pathogenesis of autoimmune diseases. Among these environmental factors, the role of infection is known to be a major one. Epstein–Barr virus (EBV) and cytomegalovirus (CMV) are considered to be notorious as they are consistently associated with multiple autoimmune diseases. A cohort of 1595 serum samples, of 23 different autoimmune disease groups, was screened for evidence of prior infection with EBV and CMV. All samples were screened for antibodies against EBV nuclear antigen‐1 (IgG), EBV viral capsid antigen (IgG and IgM), EBV early antigen (IgG), EBV heterophile antibody, and CMV (IgG and IgM) antibodies using Bio‐Rad's BioPlex 2200. A new association is proposed between EBV and polymyositis, as results show a significant increase in titers of various EBV target analytes when compared with healthy controls. Our results also support prior information suggesting the association between EBV and multiple autoimmune diseases, including SLE, antiphospholipid syndrome, rheumatoid arthritis, multiple sclerosis, pemphigus vulgaris, giant cell arthritis, Wegener's granulomatosis, and polyarteritis nodosa (PAN). Elevated CMV IgG titers were observed in sera of SLE patients. Our data support the theory that EBV is notoriously associated with many autoimmune diseases. CMV appears to be associated to autoimmune diseases as well, yet establishing this theory requires further investigation.
c-Jun N-terminal Kinase Inhibitor II (SP600125) Activates Müllerian Inhibiting Substance Type II Receptor-Mediated Signal Transduction
Authors: Renlund Nina , Pieretti-Vanmarcke Rafael , O’Neill Francis H. , Zhang LiHua , Donahoe Patricia K. , Teixeira Jose
Published: October 2007

Müllerian inhibiting substance (MIS), the hormone required for Müllerian duct regression in fetal males, is also expressed in both adult males and females, but its physiological role in these settings is not clear. The expression of the MIS type II receptor (MISRII) in ovarian cancer cells and the ability of MIS to inhibit proliferation of these cells suggest that MIS might be a promising therapeutic for recurrent ovarian cancer. Using an MISRII-dependent activity assay in a small-molecule screen for MIS-mimetic compounds, we have identified the c-Jun N-terminal kinase inhibitor SP600125 as an activator of the MIS signal transduction pathway. SP600125 increased the activity of a bone morphogenetic protein-responsive reporter gene in a dose-dependent manner and exerted a synergistic effect when used in combination with MIS. This effect was specific for the MISRII and was not seen with other receptors of the TGFβ family. Moreover, treatment of mouse ovarian cancer cells with a combination of SP600125 and paclitaxel, an established chemotherapeutic agent used in the treatment of ovarian cancer, or with MIS enabled inhibition of cell proliferation at a lower dose than with each treatment alone. These results offer a strong rationale for testing the therapeutic potential of SP600125, alone or in combination with already established drugs, in the treatment of recurrent ovarian cancer with a much-needed decrease in the toxic side effects of currently employed therapeutic agents.
Inactivation of the Oxytocin and the Vasopressin (Avp) 1b Receptor Genes, But Not the Avp 1a Receptor Gene, Differentially Impairs the Bruce Effect in Laboratory Mice (Mus musculus)
Authors: Wersinger Scott R. , Temple Jennifer L. , Caldwell Heather K. , Young W. Scott
Published: October 2007

The Bruce effect is a pheromonally mediated process whereby exposure to chemosensory cues from an unfamiliar male terminates pregnancy in a recently mated female. Pharmacological and genetic evidence implicates both oxytocin (Oxt) and vasopressin (Avp) in the regulation of social memory in males, but less work has been done in females. We tested the extent to which the Avp receptors (Avprs) 1a and 1b and Oxt are essential for the Bruce effect, a phenomenon that relies on olfactory memory. Adult female mice were paired with stimulus males and monitored for the presence of sperm plugs. Wild-type, heterozygous, and homozygous knockout (KO) females for either the Avpr1a, Avpr1b, or Oxt genes were randomly assigned to one of the following treatment groups: 1) alone (mate removed, no second exposure to another animal); 2) paired continuously (mate kept with female for 10–14 d); 3) familiar male (mate removed, reintroduced 24 h later); or 4) unfamiliar male (mate removed, BalbC male introduced 24 h later). Regardless of genotype, 90–100% of females in the alone or paired continuously groups became pregnant. The Oxt KO females terminated their pregnancies regardless of whether their original mate or an unfamiliar male was reintroduced. The Avpr1b KO mice failed to terminate pregnancy in the presence of an unfamiliar male. The Avpr1a KO mice exhibited a normal Bruce effect. These data demonstrate that both Oxt and the Avpr1b are critical for the normal expression of the Bruce effect but have different effects on the interpretation of social cues.
Sperm release strategies in marine broadcast spawners: the costs of releasing sperm quickly
Authors: Marshall Dustin J. , Bolton Toby F.
Published: October 2007

When under competition for fertilisations, males are thought to increase their reproductive success by releasing as many sperm as possible into the reproductive arena and in many species, this prediction holds. For marine invertebrates, which utilise the ancestral strategy of broadcast spawning eggs and sperm, however, it appears that males tend to release their sperm more slowly than females release their eggs. Marine invertebrate eggs typically have a relatively slow permanent block to polyspermy (whereby eggs become impermeable to further sperm attachment), and for several minutes after fertilisation, sperm can continue to attach to a fertilised egg. We hypothesised that releasing sperm slowly minimises the `wastage' of sperm on already fertilised eggs. We simulated different sperm release rates in a flume using the broadcast spawning polychaete, Galeolaria caespitosa. Sperm release rates strongly affected overall fertilisation success: higher release rates resulted in lower fertilisation rates. Laboratory studies confirmed that the `permanent' block to polyspermy in G. caespitosa took less than a minute to form but this lag was sufficient to result in some sperm wastage. Thus upstream, fertilised eggs that have not formed a permanent block to polyspermy can remove sperm from the pool that would otherwise fertilise downstream sibling eggs. We suggest that while electrical blocks to polyspermy evolved in response to excess sperm, permanent blocks to polyspermy could have evolved in response to sperm limitation (insufficient sperm).
Non-linearity and non-smoothness in multi-body dynamics: Application to woodpecker toy
Authors: Slavič J , Boltežar M
Published: October 2007

The introduction of the article gives a short historical overview of the modelling of multi-body dynamics with unilateral contacts. The unilateral contacts formulation as introduced by Pfeiffer and Glocker is adapted to discretely defined body shapes. By using two-step collision detection, a fast and exact collision detection is achieved. The procedures are tested on a numerical example of the woodpecker toy and the results are compared with those of other authors who used a simpler mathematical model.
Two-dimensional and three-dimensional self-sustained flow oscillations in interrupted fin heat exchangers
Authors: Croce G , D'Agaro P
Published: October 2007

A numerical analysis of three-dimensional flow structures in a nominally two-dimensional fin geometry is presented. A sinusoidal louvred fin is considered. The heat transfer enhancement is achieved by combining boundary layer interruptions and vortical structures induced by the corrugation of the base fin. The fin shape and pitch, as well as flow conditions, are representative of typical automotive application. A wide ranging values of Reynolds number are investigated, spanning the steady laminar regime, the unsteady periodic laminar flow, and the chaotic transitional flow. Two- and three-dimensional numerical solutions are compared, looking for the onset of three-dimensional instabilities. At low values of the Reynolds number, up to the steady-unsteady flow transition, the flow is two-dimensional. As soon as unsteady oscillation appears, the simulation results show three-dimensional flow structures, even in a nominally two-dimensional geometry. The typical longitudinal vortex size is evaluated. In the periodic unsteady regime, fully three-dimensional computations yield time-averaged Nusselt number and friction factor significantly higher than those predicted by two-dimensional models. Furthermore, these flow structures induce an early transition from the periodic regime to the chaotic regime. In the chaotic regime, however, the heat transfer enhancement due to the three-dimensional flow structures is much lower.
Dynamic analysis and simulation of a six degree of freedom Stewart platform manipulator
Authors: Guo H B , Li H R
Published: October 2007

This article presents the explicit compact closed-form dynamic equations in the task-space by applying the combination of the Newton—Euler method with the Lagrange formulation including the dynamics of the legs for the Stewart platform manipulator. The kinematics analysis of the manipulator is given and the velocity and the acceleration formulae needed to derive the dynamic equations are also derived. The driving forces acting on the legs are determined according to the dynamic formulation. The formulation has been implemented in routines and has been used for studying a few inverse dynamic problems of a specific Stewart platform manipulator. Simulation results reveal the effect of the leg inertia and that of its parts, respectively, on the dynamics of the complete system, and numerical examples show the effectiveness of the proposed method and the dynamic equations of the Stewart platform manipulator.
When does a notch behave like a crack?
Authors: Dini D , Hills D A
Published: October 2007

The characteristic asymptotic fields at the tip of sharp, semi-infinite cracks and notches are first compared with corresponding features present in selected finite bodies (edge cracks and notches). This gives an explicit view of the gradual divergence of the semi-infinite and finite problem solutions as the observation point becomes remote from the tip. Hence, upper bounds for the local plastic zone to be characterized by the singular field are known. Asymptotic solutions for semi-infinite rounded features are introduced, whose remote fields may be matched to the sharp singular fields through the medium of the corresponding generalized stress intensity factor. Thus the semi-infinite sharp and rounded problems converge remotely but diverge as the apex of the feature is approached. This comparison sets a lower bound for loads at which the outer boundary of the plastic zone is characterized by the singular field. Thus, the range of loads for the plastic zones to be controlled by the singular solutions are derived. We then proceed to compare critically the nature of the semi-infinite sharp notch and semi-infinite crack states of stress, defining the circumstances in which these are alike.

All these elements considered together enable the closeness of various notch plastic zones to that of the classical semi-infinite crack to be gauged.
Effect of inlet port on the flow in the cylinder of an internal combustion engine
Authors: Yasar A , Sahin B , Akilli H , Aydin K
Published: October 2007

In this study, the characteristics of flow emerging from the inlet of the intake port in the cylinder were investigated experimentally. A particle image velocimetry (PIV) technique was used to measure the velocity distribution in order to observe and analyse the flow behaviour. High-image-density PIV provided acquisition of patterns of instantaneous and averaged vorticity and velocity, revealing the detail of the flow characteristics in the cylinder cavity. With this measuring technique, it is possible to study the effect of intake valve geometry on the flow behaviours.

The results showed that the flow structure changed substantially along the cylinder stroke due to the geometry of the intake valve port.
Numerical and experimental analyses of radial cams with circular-arc profiles
Authors: Lanni C , Carbone G , Ceccarelli M , Ottaviano E
Published: October 2007

Cam profiles with circular arcs can be useful for low-cost transmissions and for applications in micromachines. They are usually designed by means of graphical techniques. Recently, at Laboratory of Robotics and Mechatronics (LARM) in Cassino, a research line addressed the problems of modern design and characterization of cams with circular-arc profiles by looking at computer-oriented formulations and by investigating experimentally the operation characteristics. In this article, we have given an overview of the results achieved for radial cams and also attempted to extend to a general case that is useful for studying and validating any planar cam profile. The approach is algebraic, because it is based on the geometry of the mechanical design of circular-arc profiles. The experimental analysis has been conceived for a low-cost easy-operation performance of the circular-arc profiles, using a suitable test-bed that has been designed at LARM in Cassino. The results of the experimental tests are useful to validate both the numerical design procedure and the designed cam profiles. Examples are reported to illustrate the practical engineering feasibility of the proposed analysis procedures for radial cams with circular-arc profiles.
Re-analysis of modal values by the change of design parameter
Authors: Lee J Y , Aminudin B A , Oh J-E
Published: October 2007

This study predicts the modified structural eigenvectors and eigenvalues due to the change in the mass and stiffness of a structure. The sensitivity coefficient is calculated iteratively using the original dynamic characteristics. The method is illustrated by a numerical example of a cantilever beam. An analysis of the mass and stiffness changes was performed and estimates made to predict change amount. The predicted amount changes in natural frequency and in vibration mode were compared, and it was found that the predicted dynamic characteristics using the modified mass and stiffness results showed good agreement.
Collapse of square metal tubes in splitting and curling mode
Authors: Huang X , Lu G , Yu T X
Published: October 2007

This paper presents a further investigation into the energy absorbing behaviour of axially splitting and curling square mild steel and aluminium tubes. Both quasi-static and dynamic tests were conducted. A simple quasi-static kinematic model is developed which describes all the main features of the deformation process. It is assumed in this model that cracks start from the four corners and propagate along the axial direction due to continuous fracture/tearing. The free side plates so formed by cracks roll up into four curls with a constant radius. Formulas for the average crush force, curl radius, and the energy absorption are achieved by analysing the ‘far-field’ and ‘near-tip’ deformation events and the bending moment at the crack tip. This quasi-static model is also extended and used for dynamic cases to explore strain-rate effects in splitting square metal tubes. Solutions are presented and detailed comparisons are made between theoretical predictions and experimental results.
Making better springs using aspects of chaos theory
Authors: Wood D A
Published: October 2007

This paper outlines two projects concerned with the quality testing of wire and strip metal used for the formation of springs and attempts of in-line control of a (helical) spring coiling machine for wire. The Fracmat project was a highly successful attempt to test wire for its coilability, which is known to be due to sequential variability. Methods from chaos theory, notably the Packard-Takens plot, were used to extract information that had otherwise been ignored to produce a test that could successfully distinguish between good wire and poor wire which otherwise satisfied all other available quality tolerances.
Robust vibration control of a flexible arm subjected to torque disturbance
Authors: Choi S-B
Published: October 2007

This paper presents a perturbation estimator in sliding mode control system and applies it to vibration control of a flexible arm subjected to torque disturbance. The proposed estimator is featured by an integrated average value of the imposed perturbation over a certain sampling period. By implementing this type of estimator, undesirable chattering phenomenon can be effectively alleviated in the estimation process. In addition, the proposed method offers a flexibility for tuning the ratio of the estimation sampling time to the control input sampling time. In order to demonstrate the effectiveness of the proposed methodology, a single-link flexible arm is constructed. After formulating the governing equation of motion, a sliding mode controller which is integrated with the proposed estimator is designed. Vibration control performances of the flexible arm subjected to sinusoidal torque disturbances are evaluated through both computer simulation and experimental realization.
Injection characteristics of non-swirling and swirling annular liquid sheets
Authors: Ibrahim E A , McKinney T R
Published: October 2007

A simplified mathematical model, based on body-fitted coordinates, is formulated to study the evolution of non-swirling and swirling liquid sheets emanated from an annular nozzle in a quiescent surrounding medium. The model provides predictions of sheet trajectory, thickness, and velocity at various liquid mass flowrates and liquid-swirler angles. It is found that a non-swirling annular sheet converges towards its centreline and assumes a bell shape as it moves downstream from the nozzle. The bell radius and length are more pronounced at higher liquid mass flowrates. Both the thickness and the stream-wise velocity of the non-swirling annular sheet are reduced with an increase in mass flowrate. The introduction of swirl results in the formation of a diverging hollow-cone sheet. The hollow-cone divergence from its centreline is enhanced by an increase in liquid mass flowrate or liquid-swirler angle. The hollow-cone sheet radius, curvature, and stream-wise velocity increase, whereas its thickness is diminished as a result of increasing the mass flowrate or liquid-swirler angle. The tangential velocity is greater at higher mass flowrates or smaller liquid-swirler angles. The present results are compared with previous studies and conclusions are drawn.
A method for solving compressible flow equations in an unsteady free stream
Authors: Karabasov S A , Hynes T P
Published: October 2007

The paper presents a method to increase the computational accuracy by preserving additional constraints on the numerical solution. The new technique can noticeably increase the precision of a standard finite-volume flow solver by a modification to the flux computation procedure without changing its essential features. The efficiency of this method is demonstrated by application to the prediction of sound from high-speed helicopter blades. Several open domain boundary conditions for this application are also developed and compared for a model problem of a two-dimensional transonic aerofoil in an unsteady free stream.
Vibration-based damage detection in structures using time series analysis
Authors: Trendafilova I
Published: October 2007

The paper considers some possibilities to use pure time series analysis for damage diagnosis in vibrating structures. It introduces the basics of the state space methodology and discusses a number of possible methods to extract damage sensitive features from the state space representation of the attractor of a vibrating system. The discussed methods can be divided into two groups: methods that use non-linear dynamics characteristics and methods based on the statistical characteristics of the distribution of points on the attractor. Each possible damage feature is introduced separately and the advantages and shortfalls of its application are discussed. The application of the suggested techniques is demonstrated on a test case of a reinforced concrete plate.
Theoretical and practical investigations regarding the influence of the Serration's geometry and position on the tooth surface roughness by shaving with plunge gear cutter
Authors: Hsu R-H , Fong Z-H
Published: October 2007

Surface roughness of the work gear after plunge shaving is primarily affected by the arrangement of the serrations. A mathematical model for the serration cutting edge of the plunge shaving cutter is proposed, taking into consideration the necessary hollow tooth form. On the basis of the proposed mathematical model, the influence of the serration's geometry and position of the plunge shaving cutter on the tooth surface roughness of shaved gear are studied. The shaving process is divided into two categories: up-cutting and down-cutting. The surface roughness of the work gear is improved if the cutting edge of the serrations is arranged for up-cutting as much as possible. Experiments were conducted to validate the up-cutting assumption.
Noise reduction in linear variable differential transformer data of recoil motion measurement by numerical methods
Authors: Bhatnagar R M
Published: October 2007

The measurement of recoil distance versus time by various methods such as the recoil potentiometer, photo electric transducer, slide wire, accelerometer, revolving drum system, and linear variable differential transformer (LVDT) has been used for gross muzzle brake efficiency measurements and recoil system performance evaluation by the calculation of recoil velocities. For a long recoil-length gun system, a combination of recoil potentiometer and LVDT is used extensively. In order to dispense with the use of recoil potentiometer in the above combination, the article proposes the use of the least-square-fit-based Richardson's extrapolation method and mean square velocity calculation for the accurate determination of free recoil velocity. The mean square velocity calculation is based on Parseval's theorem. The proposed method is based on the comparative evaluation of second- and third-order finite difference method, Richardson's fourth-order method, and the least-square-fit-based Richardson's extrapolation. The least-square-fit-based Richardson's extrapolation gives the lowest value of residual entropy. This is because the maximum likelihood estimators for Gauss probability distribution function and least-square estimators for the coefficients of polynomial representing recoil velocity time curve are coincident. The results of each of the four methods combined with the mean square velocity method were compared, and the least-square-fit-based Richardson's extrapolation was found to be accurate and consistent. The method can be used even when low pass filter is included in the LVDT circuit for stand-alone use.
Ride quality investigation of an electrorheological seat suspension to minimize human body vibrations
Authors: Han Y M , Jung J Y , Choi S B , Choi Y T , Wereley N M
Published: October 2007

This paper presents vibration control performance of a semi-active electrorheological (ER) seat suspension incorporating a vibration model of the human body. A cylindrical type of ER seat damper is manufactured and its field-dependent damping force is experimentally evaluated. A human body model is derived and integrated with the governing equations of an ER seat suspension, which consists of seat, spring, and ER seat damper. The seat-driver model is then reduced through a balanced model reduction in order to design a state observer from which the state of each human body segment is obtained for evaluation. A semi-active skyhook controller is then designed, and control responses (ride quality) are evaluated in both time and frequency domains through computer simulation and experimental realization. In addition, a comparison of the proposed semi-active ER seat suspension to a conventional passive seat suspension system is undertaken.
Differentiation between ‘good’, ‘borderline’, and ‘poor’ ASTM lubricant standards by ring zone sampling and multivariate data analysis
Authors: Aruna M A , G Datoo A N , Fox M F
Published: October 2007

The relative degradation of lubricant formulations corresponding to ASTM sequence IIIF and VG, ‘good’, ‘borderline’, and ‘poor’ test lubricants was investigated by piston ring zone sampling from an operating petrol engine over 25 hour test runs. Chemical/physical analyses of the lubricant samples for each formulation gave a data base that was examined by several multivariate techniques.

Very clear separation is obtained between the ‘good’, ‘borderline’, and ‘poor’ lubricant formulations. Further analyses of base oil and additive pack contributions to the data base show that the ‘good/pass’ lubricant formulation maintains a close cohesive grouping of physical and chemical properties throughout the test. The ‘poor/fail’ lubricant formulation properties move towards the ‘good/pass’ formulation as the test proceeds. The ‘borderline’ lubricant formulation loses additive pack effectiveness after ∼ 60 per cent of the test duration, thereafter giving erratic database result ‘outliers’.

Ring zone sampling of lubricant formulations, their chemical/physical analyses together with chemometrics is an effective, rapid, and cost effective method for separating the ASTM sequence III and V performance levels of ‘good’, ‘borderline’, and ‘poor’ lubricant formulations.
Improving driving ability for a two-wheeled inverted-pendulum-type autonomous vehicle
Authors: Kim Y , Kim S H , Kwak Y K
Published: October 2007

As the use of robotic mechanisms in various fields increases, the dynamics of many kinds of mechanism have to be thoroughly understood and analysed for safe and stable operation. This study is concerned with the enhancement of floor-driving ability for a two-wheeled inverted-pendulum-type autonomous vehicle. This type of robotic mechanism is innately unstable, therefore stabilization of the robot's body posture is primarily needed. For more stable driving at high speeds, the exact dynamics of this robotic mechanism was investigated using Kane's dynamic modelling. By analysing the dynamics and the system as a whole, the vehicle's stability at higher speeds was improved. The experimental results with various types of motion confirmed the enhancement of the robot's driving ability.
An improved non-dimensional model of wet-cooling towers
Authors: Qureshi B. A. , Zubair S. M.
Published: October 2007

A general non-dimensional mathematical model of cooling towers is improved by including evaporation of water. The solution still consists of adjusting the assumed straight air-saturation line to the real air-saturation data, but a new constant ( H) is added as well. Two solutions are proposed and the accuracy of each method is checked against data from the literature and also compared with the original solution. The first method shows a maximum decrease of 4.4 per cent in error, whereas in the second method, the maximum error was found to be 3.3 and 6.8 per cent when the inlet air was unsaturated and saturated, respectively.
Finite element simulation of mechanical stress relieving in welded pipe—flange joint
Authors: Siddique M , Abid M
Published: October 2007

The mechanical stress relieving (MSR) treatment is commonly employed as post-weld stress relieving process in pressure vessels. Its application to piping system is rarely reported in the literature. This article presents a three-dimensional finite-element analysis for MSR in welded pipe—flange joint of carbon—manganese steel. Sequentially coupled transient, non-linear thermo-mechanical analysis for single pass gas metal arc welding is first performed to calculate welding residual stresses. Subsequently, separate parametric studies for three different types of MSR loads including internal pressure, external pressure, and axial pull are performed on the pre-stressed model and stress-relieving behaviour is studied. The method of post-weld MSR has found an effective way for mitigation of the residual stresses in the piping systems. It is concluded that both the internal pressure and the axial pull have significant effect on the residual stresses on the inner surface of the joint.