bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Porphyromonas gingivalis on human gingival fibroblasts from healthy and inflamed tissues
Authors: Al‐Shibani Nouf , Windsor L. Jack
Published: June 2008

Background and Objective:  This study compared the ability of human gingival fibroblasts (HGFs) isolated from healthy and inflamed gingival tissues to degrade collagen in the presence and absence of Porphyromonas gingivalis supernatant.

Material and Methods:  Human gingival fibroblasts were cultured from explants of 21 healthy and 21 inflamed periodontal tissues. The HGFs that grew out of the explants were seeded in the center of six‐well plates coated with collagen in the presence and absence of 10%P. gingivalis supernatant. An inflamed and a healthy cell line were also evaluated with Arg‐gingipain. After 6 days, Coomassie Blue was used to visualize the collagen cleavage.

Results:  The collagen was totally cleaved in 12 (aggressive) of the 21 cell lines isolated from the inflamed tissues in the presence of P. gingivalis. The remaining nine cell lines (non‐aggressive) cleaved only the collagen underneath the cell colonies in the presence of P. gingivalis. Of the healthy tissues, five (aggressive) of the 21 cell lines cleaved all the collagen and 16 cell lines (non‐aggressive) only cleaved the collagen underneath the cell colonies in the presence of P. gingivalis. All the collagen was cleaved by an aggressive cell line and only the collagen underneath the cell colonies was cleaved by a non‐aggressive cell line in the presence of Arg‐gingipain.

Conclusion:  The collagen in the wells was more readily cleaved by the inflamed than by the healthy cell lines, and the difference was statistically significant (p = 0.0278). Arg‐gingipain gave identical results to the P. gingivalis supernatant.
In Situ Cleavage of the Acidic Domain from the p115 Tether Inhibits Exocytic Transport
Authors: Satoh Ayano , Warren Graham
Published: June 2008

Golgins are coiled‐coil proteins involved in Golgi architecture and function. A complex of golgins (p115, GM130 and giantin), together with the rab1 guanosine triphosphatase and cis Golgi SNAREs, helps to mediate fusion processes at the entry face of the Golgi apparatus. The C‐terminal acidic domain of p115 binds specifically to GM130 and giantin. However, deletion of this domain in vivo appears to have no effect on exocytic transport when using an RNA interference depletion/rescue approach (Puthenveedu MA, Linstedt AD. Gene replacement reveals that p115/SNARE interactions are essential for Golgi biogenesis. Proc Natl Acad Sci U S A 2004;101:1253–1256). In this study, we have used a different approach introducing a tobacco etch virus (tev) protease cleavage site into p115 so that the C‐terminal domain can be rapidly and specifically released in vivo by microinjection of the tev protease. The results show that cleavage inhibits exocytic transport to the cell surface.
Oral graft‐versus‐host disease
Authors: Imanguli MM , Alevizos I , Brown R , Pavletic SZ , Atkinson JC
Published: June 2008

Objective:  Graft‐versus‐host disease (GVHD) is a leading cause of morbidity and mortality in patients receiving hematopoietic cell transplant. It is estimated that 40–70% of engrafted patients surviving the initial transplant eventually develop chronic GVHD (cGVHD), which can persist for months to years and require long‐term management from multiple disciplines. This review describes the oral component of this transplant complication.

Design:  The search related to GVHD patho‐biology, salivary gland disease after hematopoietic cell transplant and treatments for oral GVHD encompassed literature from 1966 through 2008. Searches were limited to the MEDLINE/PubMed database and English language literature in peer‐reviewed journals.

Results:  Our understanding of the patho‐biology of oral cGVHD is based on studies of other affected tissues. It is difficult to determine the prevalence and incidence of salivary gland disease after transplant because there is no universally accepted case definition. In general, clinical trials for treatment of oral cGVHD have been too small to make strong recommendations for use in clinical practice.

Conclusions:  Larger well‐designed clinical studies are needed to understand the patho‐biology of oral cGVHD and determine best treatments for this disease.
Peroxiredoxin I is differentially expressed in multiple myelomas and in plasmablastic lymphomas
Authors: Demasi APD , Magalhães MHC , Furuse C , Araújo NS , Junqueira JLC , Araújo VC
Published: June 2008

Background:  Plasmablastic lymphoma (PBL) and multiple myeloma (MM) are B cell‐derived malignancies that share many morphologic and immunophenotypic traits, making the differential diagnosis particularly complicated. We have recently demonstrated that peroxiredoxin I (PrdxI) is expressed in plasma cells but not in B lymphocytes, suggesting that its expression is development‐associated.

Aim:  To analyze PrdxI expression in PBL and in MM in order to study its utilization as an additional diagnostic molecular tool.

Methods and results:  Eight cases of PBL and nine of MM were studied by immunohistochemistry. We have demonstrated that PrdxI expression is closely connected with the immunoglobulin production capacity of the cells, which means high in MM, but absent in PBL cases, except one, wherein few cells were stained.

Conclusions:  We hypothesize PrdxI as a component of the unfolded protein response (UPR), an adaptive pathway essential for plasma cell differentiation. As we have not detected immunoglobulin in our PBL cases, we suggest that UPR was not activated in the cells, accounting for the impediment of the developmental process, and for the inhibition of PrdxI expression observed. PrdxI could be considered an additional plasma cell functional marker and could also be speculated as a therapeutic target in the treatment of MM.
The Anatomy of the Distal Vagina: Towards Unity
Authors: O'Connell Helen E. , Eizenberg Norm , Rahman Marzia , Cleeve Joan
Published: June 2008

Introduction

Factual presentations of sexual anatomy are required for educational purposes, for clinical and more general communication about sexual matters. To date, unambiguous, accurate and objective images with appropriate labeling to enhance specificity in communication have been lacking.

Aim

The aim of this presentation is to provide a comprehensive overview of anatomy of the distal vagina. We aim to simplify the anatomy to reduce the confusion of historical descriptions. In doing so, we aim to avoid sacrificing any of the specific detail. This would aid communication between clinicians, researchers, and the nonclinician regarding this anatomy.

Outcome Measures and Methods

This article reviews the historical and current anatomical literature. Systematic dissection and photography, histological study, and magnetic resonance imaging have been used as the basis for this presentation. Digital technology has been used to label, color, and highlight photography to provide clarity and permit diagramatization of photography. No distortion has otherwise been used in presenting images from cadavers or anatomical research.

Results

The anatomy of the distal vagina and surrounding structures is shown and described in detailed. The distal vagina, clitoris, and urethra form an integrated entity covered superficially by the vulval skin and its epithelial features. These parts have a shared vasculature and nerve supply and during sexual stimulation respond as a unit though the responses are not uniform.

Conclusion

Significant progress has been made in the field of female sexual anatomy and its pictorial representation. This may facilitate further progress in the related fields of female sexual health and education.
Intracavernous Growth Differentiation Factor-5 Therapy Enhances the Recovery of Erectile Function in a Rat Model of Cavernous Nerve Injury
Authors: Fandel Thomas M. , Bella Anthony J. , Lin Guiting , Tantiwongse Kavirach , Lin Ching-Shwun , Pohl Jens , Lue Tom F.
Published: June 2008

Introduction

Neurogenic erectile dysfunction remains a serious complication in the postprostatectomy population. Effective protective and regenerative neuromodulatory strategies are needed.

Aim

To determine the effect of growth differentiation factor-5 (GDF-5) on erectile function and its mechanism in a rat model of cavernous nerve (CN) injury.

Main Outcome Measures

Erectile function was assessed by CN electrostimulation at 4 weeks. Penile tissues were examined by real-time polymerase chain reaction (PCR) and immunohistochemical analyses.

Methods

Forty-eight male Sprague-Dawley rats were randomly divided into six equal groups: one group underwent sham operation (uninjured controls), while five groups underwent bilateral CN crush. Crush-injury groups were treated at the time of injury with intracavernous injection of a slow-release suspension of liquid microparticles containing no GDF-5 (vehicle), 0.4 µg (low concentration), 2 µg (intermediate concentration), or 10 µg GDF-5 (high concentration). One untreated group served as injured controls.

Results

GDF-5 enhanced erectile recovery and significantly increased intracavernous pressure in the low and intermediate-concentration groups vs. injured controls. Low-concentration GDF-5 demonstrated the best functional preservation, as the intracavernous pressure increase in this group did not differ significantly from uninjured controls. A dose-response relationship was confirmed for the effects of GDF-5 in penile tissue. Low-concentration GDF-5 showed better preservation of the penile dorsal nerves and antiapoptotic effects in the corpus cavernosum (P < 0.05 vs. injured controls). Although high concentration GDF-5 did not confer meaningful erectile recovery, this dose was more effective at decreasing transforming growth factor-β than low-concentration GDF-5.

Conclusion

Intracavernous injection of low (0.4 µg) or intermediate-concentration GDF-5 (2 µg) was effective in preserving erectile function in a rat model of neurogenic erectile dysfunction. The underlying mechanism appears to involve neuron preservation and antiapoptosis.
Clinical and Psychosocial Factors Associated with Quality of Life in Alcohol-Dependent Men with Erectile Dysfunction
Authors: Ponizovsky Alexander M.
Published: June 2008

Introduction

Men with alcohol dependence (AD) commonly suffer from alcohol-induced sexual (erectile) dysfunction (ED) and have poor quality of life (Qol). Knowledge about the factors associated with Qol in such patients is lacking.

Aim

To identify in men who sought medical help for both AD and ED the variables that best predicted feelings of satisfaction with life and with specific life domains.

Main Outcome Measures

The Quality of Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q). Secondary study measures were the International Index of Erectile Function (IIEF), Beck Depression Inventory (BDI-13), General Health Questionnaire (GHQ-12), Rosenberg's General Self-Esteem Scale (RGSES), and the Multidimensional Scale of Perceived Social Support (MSPSS).

Methods

Within an open-label sildenafil trial, 101 men aged 18–50 years with an International Classification of Diseases, Tenth Edition diagnosis of AD and concomitant ED were interviewed and completed the questionnaires. Multivariate analyses were applied to establish predictors of life satisfaction and factors mediating the relation between ED and life satisfaction.

Results

ED and self-rated depressive symptoms, emotional distress, self-esteem, and perceived social support were found to be significantly associated with Qol and its component domains. Altogether they explained 18–38% of the variance in the Qol ratings. Depressive symptomatology, distress, and self-esteem, individually, demonstrated a mediating effect on the relation between ED and Qol. Finally, self-esteem was shown to be the primary mediator in this relationship.

Conclusion

The results of the study show that self-esteem is the primary factor, and depressive symptoms and severe emotional distress are secondary factors mediating the effects of ED on Qol in male patients seeking medical help for both AD and ED. An integrated pharmacopsychosocial approach targeting the underlying ED as well as the mediating emotional conditions could improve Qol of these patients and thus help them to stop using alcohol.
Global warming potential of wheat production in Western Australia: a life cycle assessment
Authors: Biswas Wahidul K. , Barton Louise , Carter Daniel
Published: June 2008

This study presents a greenhouse gas (GHG) life cycle assessment of 1 tonne of wheat transported to port in south‐western Australia, including emissions from prefarm, onfarm and postfarm stages. The prefarm stage included GHG emissions from agricultural machinery, fertiliser and pesticide production. The onfarm stage included GHG emissions from diesel use, liming and nitrous oxide (N2O) emissions from N fertiliser applications. The postfarm stage included grain storage and transportation to the port. GHG emissions decreased from 487 to 304 kg carbon dioxide (CO2) equivalents when we used regional‐specific data for N2O emissions instead of the IPCC default value for the application of synthetic N fertilisers to land (1.0%). Fertiliser production in the prefarm stage contributed significantly (35%) to GHG, followed by onfarm CO2 emissions (27%) and emissions from transportation of inputs and wheat (12%). N2O emissions from paddock represented 9% of the total GHGs emitted. We recommend utilising regionally specific data for soil N2O emissions, rather than international default values, when assessing GHG for agricultural production systems.
Extracellular matrix profiles in the progression to heart failure
Authors: Graham H. K. , Horn M. , Trafford A. W.
Published: June 2008

The myocardial extracellular matrix (ECM), which preserves the geometry and integrity of the myocardium, is a dynamic structure whose component proteins are maintained by a finely controlled homeostatic balance between deposition and degradation. One of the key targets in cardiology is the elucidation of the molecular mechanisms which mediate pathological remodelling of this matrix causing the transition from compensatory hypertrophy to congestive decompensated heart failure. In response to injury or increased workload, cardiac remodelling including myocyte hypertrophy, develops as the heart attempts to compensate for increased wall stresses. Persistence of these stresses over extended time periods leads to disruption of ECM homeostasis resulting in irreversible maladaptive cardiac remodelling, ventricular dilatation and finally heart failure. ECM remodelling is regulated by the matrix metalloproteinases (MMPs) and their endogenous inhibitors (TIMPs). Clinical studies and experimental models of cardiac disease states have reported alterations in the balance between the MMPs and TIMPs in the failing heart and crucially at intermediate time points in the progression to failure. This article reviews the recent clinical, genetic and experimental approaches employed to compare ECM, MMP and TIMP profiles in healthy, compensated and failing hearts and identifies common themes in the perturbation of ECM homeostasis in the transition to heart failure.
Dilatation in the femoral vascular bed does not cause retrograde relaxation of the iliac artery in the anaesthetized pig
Authors: Markos F. , Ruane‐O’Hora T. , Snow H. M. , Kelly R. , Wainwright C. , Skene K. , Drake‐Holland A. J. , Noble M. I. M.
Published: June 2008

Aim:  We tested the hypothesis that dilatation of a feeding artery may be elicited by transmission of a signal through the tissue of the arterial wall from a vasodilated peripheral vascular bed.

Methods:  In eight pentobarbital anaesthetized pigs, acetylcholine (ACh, an endothelium‐dependent vasodilator) was injected intra‐arterially above (upstream) and below (downstream) a test segment of the left iliac artery, the diameter of which was measured continuously by sonomicrometry.

Results:  Under control conditions, ACh injections upstream and downstream of the test segment caused dilatation. Downstream injection dilated the peripheral arterioles, resulting in increased blood flow and proximal dilatation. This is a shear stress, nitric oxide (NO)‐dependent response. The experiment was then repeated after applying a stenosis to prevent the increased flow caused by downstream injection of ACh; the stenosis was placed either above the site of diameter measurement to allow retrograde conduction, or below that site to prevent distally injected ACh reaching the measurement site. Under these conditions, downstream injection of ACh had a minimal effect on the shear stress of the test segment with no increase in test segment diameter. This was not due to endothelial damage or dysfunction as injection of ACh upstream still caused a large increase in test segment diameter.

Conclusions:  Our results indicate that dilatation of the feeding artery of a vasodilated bed is caused by increased shear stress within the feeding artery and not via a signal transmitted through the arterial wall from below.
‘Fundamentalisms’ Compared
Authors: Munson Henry
Published: June 2008

The term ‘fundamentalist’ is often used indiscriminately. In this essay, the term is used to refer to movements that insist on strict conformity to a sacred text and to a moral code ostensibly based on it. Such movements often also articulate secular grievances such as nationalistic resentment of foreign domination. To focus only on the fundamentalist dimension of such groups is, in some cases at least, to ignore some of the principal sources of their appeal. One should avoid assuming that moral outrage ostensibly provoked by the violation of traditional religious values is really a mere reflection of nationalistic, ethnic, or other social grievances. But one should also avoid ignoring social grievances when the available evidence suggests that they are in fact relevant.
The Neurocognition of Referential Ambiguity in Language Comprehension
Authors: Nieuwland Mante S. , Van Berkum Jos J. A.
Published: June 2008

Referential ambiguity arises whenever readers or listeners are unable to select a unique referent for a linguistic expression out of multiple candidates. In the current article, we review a series of neurocognitive experiments from our laboratory that examine the neural correlates of referential ambiguity, and that employ the brain signature of referential ambiguity to derive functional properties of the language comprehension system. The results of our experiments converge to show that referential ambiguity resolution involves making an inference to evaluate the referential candidates. These inferences only take place when both referential candidates are, at least initially, equally plausible antecedents. Whether comprehenders make these anaphoric inferences is strongly context dependent and co‐determined by characteristics of the reader. In addition, readers appear to disregard referential ambiguity when the competing candidates are each semantically incoherent, suggesting that, under certain circumstances, semantic analysis can proceed even when referential analysis has not yielded a unique antecedent. Finally, results from a functional neuroimaging study suggest that whereas the neural systems that deal with referential ambiguity partially overlap with those that deal with referential failure, they show an inverse coupling with the neural systems associated with semantic processing, possibly reflecting the relative contributions of semantic and episodic processing to re‐establish semantic and referential coherence, respectively.
University–Industry Links and Regional Development: Thinking beyond Knowledge Spillovers
Authors: Davies Tamsin
Published: June 2008

The use, nature and movement of knowledge have a central place in recent debates concerning contemporary economies. Within this context, knowledge spillovers from universities to industry are believed to be an important driver of innovation. Because these spillovers are thought to be geographically localised, they have a potentially important role in developing the regional economy. However, the concept of the knowledge spillover, although widely accepted in the literature, is not unproblematic. This article explores the theoretical assumptions behind the academic knowledge spillover, namely that academic knowledge is a public good, inherently tacit and context‐independent. It argues that such assumptions make knowledge spillovers between universities and firms appear more likely than they in fact are. Instead, a mixture of informal and formal, market‐related activities enable knowledge flow between universities and industry. Knowledge flows are governed by processes of transfer, translation and transformation that impact on the mobilities of different types of knowledge. However, the mechanisms authors have proposed for knowledge spillovers, such as social networks, are still important. As far as the contributions, such linkages make to regional development are concerned, these may be affected by both the socio‐cultural environment of the region and extra‐regional factors.
Accessing Higher Education: The Influence of Cultural and Social Capital on University Choice
Authors: Brooks Rachel
Published: June 2008

Over recent years, sociologists of education have paid increasing attention to the higher education sector. They have highlighted the ways in which, despite the significant expansion in the number of university places available in many countries across the world, access to and choices about higher education continue to be strongly influenced by social class. This article provides an overview of recent literature in this field and explores how scholars have tended to explain this influence by drawing on Pierre Bourdieu's concepts of habitus and cultural and social capital.
Perinatal and chronic hypothyroidism impair behavioural development in male and female rats
Authors: Van Wijk N. , Rijntjes E. , Van De Heijning B. J. M.
Published: June 2008

A lack of thyroid hormone, i.e. hypothyroidism, during early development results in multiple morphological and functional alterations in the developing brain. In the present study, behavioural effects of perinatal and chronic hypothyroidism were assessed during development in both male and female offspring of hypothyroid rats. To induce hypothyroidism, dams and offspring were fed an iodide‐poor diet and drinking water with 0.75% sodium perchlorate; dams starting 2 weeks prior to mating and pups either until the day of killing (chronic hypothyroidism) or only until weaning (perinatal hypothyroidism) to test for reversibility of the effects observed. Neuromotor competence, locomotor activity and cognitive function were monitored in the offspring until postnatal day 71 and were compared with age‐matched control rats. Early neuromotor competence, as assessed in the grip test and balance beam test, was impaired by both chronic and perinatal hypothyroidism. The open field test, assessing locomotor activity, revealed hyperactive locomotor behavioural patterns in chronic hypothyroid animals only. The Morris water maze test, used to assess cognitive performance, showed that chronic hypothyroidism affected spatial memory in a negative manner. In contrast, perinatal hypothyroidism was found to impair spatial memory in female rats only. In general, the effects of chronic hypothyroidism on development were more pronounced than the effects of perinatal hypothyroidism, suggesting the early effects of hypothyroidism on functional alterations of the developing brain to be partly reversible and to depend on developmental timing of the deficiency.
l‐carnitine supplementation attenuates intermittent hypoxia‐induced oxidative stress and delays muscle fatigue in rats
Authors: Dutta Arkadeb , Ray Koushik , Singh Vijay K. , Vats Praveen , Singh Som N. , Singh Shashi B.
Published: June 2008

The concept of l‐carnitine (l‐CAR) supplementation to improve muscular performance is based on the role of l‐CAR in regulating aerobic metabolism. l‐CAR has also been found to attenuate free radical‐induced oxidative stress in various pathological conditions. Thus, it was hypothesized that l‐CAR may reduce intermittent hypoxia (IH)‐induced oxidative stress and thereby benefit skeletal muscle performance. Thirty‐six adult male Sprague–Dawley rats were divided into three groups: unexposed control; IH exposed (6 h day−1 for 7 consecutive days), IH exposed with l‐CAR supplementation (100 mg (kg body weight)−1 day−1). Electrical stimulation was used to induce six tetanic muscular contractions in the gastrocnemius muscle after completion of exposure. Percentage mean performed work (PW), time of decay to 50% peak force of contraction (T50), and peak force of contraction (FPeak) were measured during tetanic contractions. Mean frequency (MF) was measured using electromyography between tetanic contractions. Muscle damage was indirectly measured from plasma creatine kinase (CK) and lipid hydroperoxide (LHP) levels. The levels of thiobarbituric acid reactive substances (TBARS), protein carbonyl (PC) and LHP were estimated in the muscle tissue to investigate the efficacy of l‐CAR in attenuating oxidative stress. Significant reduction in TBARS, PC and LHP levels and CK activity in the l‐CAR‐supplemented IH group as compared to the IH placebo group suggests that l‐CAR reduces oxidative damage and thereby delays muscular fatigue, which was evident from MF, T50, PW and FPeak. From these studies, we conclude that l‐CAR delays muscle fatigue by the reducing free radical‐induced oxidative damage of IH exposure.
Differential roles of endothelin‐1 ETAand ETBreceptors and vasoactive intestinal polypeptide in regulation of the airways and the pulmonary vasculature in isolated rat lung
Authors: Janosi Tibor , Peták Ferenc , Fontao Fabienne , Morel Denis R. , Beghetti Maurice , Habre Walid
Published: June 2008

The available treatment strategies against pulmonary hypertension include the administration of endothelin‐1 (ET‐1) receptor subtype blockers (ETAand ETBantagonists); vasoactive intestinal polypeptide (VIP) has recently been suggested as a potential new therapeutic agent. We set out to investigate the ability of these agents to protect against the vasoconstriction and impairment of lung function commonly observed in patients with pulmonary hypertension. An ETAblocker (BQ123), ETBblocker (BQ788), a combination of these selective blockers (ETA+ ETBblockers) or VIP (V6130) was administered into the pulmonary circulation in four groups of perfused normal rat lungs. Pulmonary vascular resistance (PVR) and forced oscillatory lung input impedance (ZL) were measured in all groups under baseline conditions and at 1 min intervals following ET‐1 administrations. The airway resistance, inertance, tissue damping and elastance were extracted from theZLspectra. While VIP, ETAblocker and combined ETAand ETBblockers significantly prevented the pulmonary vasoconstriction induced by ET‐1, ETBblockade enhanced the ET‐1‐induced increases in PVR. In contrast, the ETAand ETBblockers markedly elevated the ET‐1‐induced increases in airway resistance, while VIP blunted this constrictor response. Our results suggest that VIP potently acts against the airway and pulmonary vascular constriction mediated by endothelin‐1, while the ETAand ETBblockers exert a differential effect between airway resistance and PVR.
Identification of ezrin as a target of gastrin in immature mouse gastric parietal cells
Authors: Pagliocca Adelina , Hegyi Peter , Venglovecz Viktoria , Rackstraw Stephen A. , Khan Zara , Burdyga Galina , Wang Timothy C. , Dimaline Rod , Varro Andrea , Dockray Graham J.
Published: June 2008

The gastric acid‐secreting parietal cell exhibits profound morphological changes on stimulation. Studies in gastrin null (Gas‐KO) mice indicate that maturation of parietal cell function depends on the hormone gastrin acting at the G‐protein‐coupled cholecystokinin 2 receptor. The relevant cellular mechanisms are unknown. The application of differential mRNA display to samples of the gastric corpus of wild‐type (C57BL/6) and Gas‐KO mice identified the cytoskeletal linker protein, ezrin, as a previously unsuspected target of gastrin. Gastrin administered in vivo or added to gastric glands in vitro increased ezrin abundance in Gas‐KO parietal cells. In parietal cells of cultured gastric glands from wild‐type mice treated with gastrin, histamine or carbachol, ezrin was localized to vesicular structures resembling secretory canaliculi. In contrast, in cultured parietal cells from Gas‐KO mice, ezrin was typically distributed in the cytosol, and this did not change after incubation with gastrin, histamine or carbachol. However, priming with gastrin for approximately 24 h, either in vivo prior to cell culture or by addition to cultured gastric glands, induced the capacity for secretagogue‐stimulated localization of ezrin to large vesicular structures in Gas‐KO mice. Similarly, in a functional assay based on measurement of intracellular pH, cultured parietal cells from Gas‐KO mice were refractory to gastrin unless primed. The priming effect of gastrin was not attributable to the paracrine mediator histamine, but was prevented by inhibitors of protein kinase C and transactivation of the epidermal growth factor receptor. We conclude that in gastrin null mice there is reduced ezrin expression and a defect in ezrin subcellular distribution in gastric parietal cells, and that both can be reversed by priming with gastrin.
Inhibition of Rac1 decreases the severity of pancreatitis and pancreatitis‐associated lung injury in mice
Authors: Binker Marcelo G. , Binker‐Cosen Andres A. , Gaisano Herbert Y. , Cosen‐Binker Laura I.
Published: June 2008

Pancreatitis is a disease with high morbidity and mortality. In vitro experiments on pancreatic acini showed that supramaximal but not submaximal cholecystokinin (CCK) stimulation induces effects in the acinar cell that can be correlated with acinar morphological changes observed in the in vivo experimental model of cerulein‐induced pancreatitis. The GTPase Rac1 was previously reported to be involved in CCK‐evoked amylase release from pancreatic acinar cells. Here, we demonstrate that pretreatment with the Rac1 inhibitor NSC23766 (100 μm, 2 h) effectively blocked Rac1 translocation and activation in CCK‐stimulated pancreatic acini, without affecting activation of its closely related GTPase, RhoA. This specific Rac1 inhibition decreased supramaximal (10 nM) CCK‐stimulated acinar amylase release (27.% reduction), which seems to be connected to the reduction observed in serum amylase (46.6% reduction) and lipase levels (46.1% reduction) from cerulein‐treated mice receiving NSC23766 (100 nmol h−1). The lack of Rac1 activation also reduced formation of reactive oxygen species (ROS; 20.8% reduction) and lactate dehydrogenase release (LDH; 24.3% reduction), but did not alter calcium signaling or trypsinogen activation in 10 nM CCK‐stimulated acini. In the in vivo model, the cerulein‐treated mice receiving NSC23766 also presented a decrease in both pancreatic and lung histopathological scores (reduction in oedema, 32.4 and 66.4%; haemorrhage, 48.3 and 60.2%; and leukocyte infiltrate, 53.5 and 43.6%, respectively; reduction in pancreatic necrosis, 65.6%) and inflammatory parameters [reduction in myeloperoxidase, 52.2 and 38.9%; nuclear factor κB (p65), 61.3 and 48.6%; and nuclear factor κB (p50), 46.9 and 44.9%, respectively], together with lower serum levels for inflammatory (TNF‐α, 40.4% reduction) and cellular damage metabolites (LDH, 52.7% reduction). Collectively, these results suggest that pharmacological Rac1 inhibition ameliorates the severity of pancreatitis and pancreatitis‐associated lung injury through the reduction of pancreatic acinar damage induced by pathological digestive enzyme secretion and overproduction of ROS.
The Measurement of Nonlinear Damping in Single-Degree-of-Freedom Systems
Authors: Rice H. J. , Fitzpatrick J. A.
Published: June 2008

The measurement and correct modelling of damping is of crucial importance in the prediction of the dynamical performance of systems for a wide range of engineering applications. In most cases, however, the experimental methods used to measure damping coefficients are extremely basic and, in general, poorly reported. This paper shows that damping is a deceptive parameter which is prone to subtle nonlinear distortion which often appears to satisfy general linear criteria. An efficient experimental method which provides for the measurement of both the linear and nonlinear damping for a single-degree-of-freedom system is proposed. The results from a numerical simulation study of a model with “drag” type quadratic damping are shown to give reliable estimates of parameters of the system when both random and impulse excitation techniques are used.
Fan Casing Noise Radiation
Authors: Koopmann G. H. , Neise W. , Cunefare K. A.
Published: June 2008

This paper presents a method for assessing the extent of casing noise radiation of a centrifugal fan relative to the aeroacoustic sources associated with the inlet box of the fan. Central to the method is a boundary element program which is used to compute the acoustic pressures on the surfaces of the fan casing in terms of its surface vibration which in this case was measured experimentally. Data from an earlier experiment was used as the starting point for this study. Available data included sound pressure measurements near and away from the inlet box of the fan and vibration measurements over the casing of the fan. Noise from the outlet duct of the fan was purposely highly attenuated. Computations of sound pressure, intensity, and power indicated that, at the blade passing frequency (300 Hz), the aerodynamic sources generated near the entrance plane of the inlet box of the fan dominate the noise spectrum in the field. On the other hand, at the first subharmonic frequency of the blade tone (150 Hz), the sound power generated from the inlet box and fan casing are within 3 dB of each other. Thus, for effective noise control at this frequency, it would be necessary to include both noise sources in the overall treatment.
On the Stability Criteria for Conservative Gyroscopic Systems
Authors: Huseyin K.
Published: June 2008

Two alternative but equivalent stability criteria for linear conservative gyroscopic systems are presented. The development of the criteria is based on the concept of symmetrizability associated with general matrices, and the results are in terms of the matrices describing the dynamical system. Although the new criteria involves a scalar parameter, the restrictions associated with an earlier result are removed, and the scope of application is broadened. An illustrative example is presented.
Dynamic Stability Analysis of High Speed Axially Moving Bands With End Curvatures
Authors: Wang K. W.
Published: June 2008

Measurements of vibration on continuous bands driven by rotating wheels show that the end curvature of the spans can greatly affect the system dynamic characteristics [1,2]. Significant error in the predicted response of a span can occur if the end curvature is neglected. To understand the global dynamic behavior of such systems under high speed operating conditions, a nonlinear model of axially moving bands with finite end curvatures is developed and analyzed in this paper. It is shown that a pitch-fork bifurcation from the trivial equilibrium state will occur at the critical speed of a perfectly straight, axially moving band and the original trivial equilibrium configuration will become unstable. However, for bands with finite end curvatures, the classical critical speed theory does not apply. The equilibrium configuration will continuously change with increasing band speed, but will remain stable. Multiple equilibrium states will occur at sufficiently high band speed, and the minimum speed for this phenomenon to happen increases with the end curvature of the band. Large oscillation coupling the multiple equilibrium states will be induced by large enough initial disturbance. The disturbance required for this to occur varies with the band end curvature and transport speed. The study provides us with new insight and guidelines toward optimizing this class of high speed mechanical systems.
Chaotic Response of a Slider Crank Mechanism
Authors: Peurach J. , Tongue B. H.
Published: June 2008

A physical and corresponding theoretical model of a slider-crank mechanism is presented that approximates the single mode response of a continuous beam under a time periodic excitation in which the spatial distribution of the forcing is in the form of a half sine wave. The purpose of the model is to investigate the existence of chaos in systems having rigid members, as opposed to the highly flexible structures most often seen in chaotic demonstrations. The experimental construct displays complicated dynamical responses, including chaos, while the idealized theoretical model only supports the existence of a period one response. However, it is shown that the addition of an extremely small external perturbation will cause the response to demonstrate what appears to be a robustly chaotic response. A comparison of the Lyapunov exponents between this construct and the experimental model show close agreement.
A Set of Orthogonal Plate Functions for Flexural Vibration of Regular Polygonal Plates
Authors: Liew K. M. , Lam K. Y.
Published: June 2008

A computationally efficient and very accurate numerical method is proposed for vibration analysis of regular polygonal plates with any combinations of clamped, simply-supported and free boundary conditions. The method involves the use of two-dimensional orthogonal polynomials generated by the Gram-Schmidt recurrence procedure. For the cases of simply supported and fully clamped hexagonal and octagonal plates, the results obtained agreed very well with those existing in the literature. The frequencies and mode shapes for several hexagonal and octagonal plates subjected to mixed boundary conditions are also presented.
Characteristic Wave Surfaces in Anisotropic Laminated Plates
Authors: Liu G. R. , Tani J. , Ohyoshi T. , Watanabe K.
Published: June 2008

A numerical method is used to determine the dispersion relation (an eigenvalue equation) of plane wave propagation in an anisotropic laminated plate. A phase velocity surface, phase slowness surface, phase wave surface, group velocity surface, group slowness surface, and group wave surface are defined and their formulae are deduced from the Rayleigh quotient and the orthogonality condition of the eigenvectors of the eigenvalue equation. The six characteristic surfaces can be used to illustrate the characteristics of plane waves and waves generated from a point source in an anisotropic laminated plate. As numerical examples, the characteristic surfaces are computed for graphite/epoxy angle ply laminated plates and for a hybrid one. The results for the graphite/epoxy laminated plates are compared with those obtained by Moon’s approximate theory.
An Application of the Generalized Polynomial Expansion Method to Nonlinear Rotor Bearing Systems
Authors: Hwang Jon Li , Shiau Ting Nung
Published: June 2008

The Generalized Polynomial Expansion Method (GPEM) is utilized to model a large-order flexible-rotor system with nonlinear supports. With the application of GPEM, a set of nonlinear ordinary differential equations are obtained. A hybrid method which combines the merits of the Harmonic Balance Method (HBM) and the Trigonometric Collocation Method (TCM) is used to solve for the nonlinear response of the system. This hybrid method together with reduction techniques can efficiently solve for the motion of the system. The overall algorithm presented provides a very efficient technique for investigating the periodic response of large-order nonlinear rotor systems. Two examples are used to illustrate the merits of the method.
Finite Element Large-Amplitude Free and Forced Vibrations of Rectangular Thin Composite Plates
Authors: Chiang C. K. , Mei C. , Gray C. E.
Published: June 2008

A finite element formulation is presented for determining the large-amplitude free and steady-state forced vibration responses of arbitrarily laminated anisotropic composite rectangular thin plates. The nonlinear stiffness and harmonic force matrices of an arbitrarily laminated composite rectangular plate element are developed for nonlinear free and forced vibration analyses. The linearized updated-mode method with nonlinear time function approximation is employed for the solution of the system nonlinear eigenvalue equations. The finite element results are compared with available approximate continuum solutions. The amplitude-frequency relations for convergence with gridwork refinement, different boundary conditions, aspect ratios, lamination angles, number of plies, and uniform versus concentrated loads are presented.
Stability and Instability of a Two-Mode Rotor Supported by Two Fluid-Lubricated Bearings
Authors: Muszynska A. , Grant J. W.
Published: June 2008

This paper is a continuation of the series of papers on application of the improved fluid force model for lightly loaded shafts rotating in a fluid environment. The fluid force model is based on the strength of the circumferential flow. The considered two-mode rotor is supported in two fluid-lubricated bearings, thus it contains two potential sources of instability. The eigenvalue solution predicts thresholds of stability and provide natural frequencies and modes of the system, including the flow-induced mode. The nonlinear model of the rotor/bearing system allows for evaluation of parameters of after instability onset self-excited vibrations (whirl and whip). Experimental data illustrate the dynamic phenomena predicted by the model. In particular, they show an undocumented new phenomenon, the simultaneous existence of two whip vibrations with frequencies corresponding to two modes of the rotor. A radial preload of the rotor results in journal eccentric position inside the bearings, which causes specific changes in the fluid forces (an increase of radial stiffness and reduction of circumferential velocity) providing better stability of the rotor. This effect is illustrated by the experimental data, as well as is predicted by the model.
Effects of Gear Box Vibration and Mass Imbalance on the Dynamics of Multistage Gear Transmission
Authors: Choy F. K. , Tu Y. K. , Zakrajsek J. J. , Townsend D. P.
Published: June 2008

The objective of this paper is to present a comprehensive approach to analyze the dynamic behavior of multi-stage gear transmission systems with the effects of gear box induced vibrations and rotor mass-imbalances. The modal method, using undamped frequencies and planar mode shapes, is used to reduce the degree of freedom of the system. The various rotor-bearing stages as well as the lateral and torsional vibrations of each individual stage are coupled through localized gear mesh tooth interactions. Gear box vibrations are coupled to the gear stage dynamics through bearing support forces. Transient and steady state dynamics of lateral an torsional vibrations of the geared system are examined in both time and frequency domains. Vibration signature analysis techniques will be developed to interpret the overall system dynamics and individual modal excitations under various operating conditions. A typical 3- staged geared system is used as an example. Effects of mass imbalance and gear box vibrations on the system dynamic behavior are presented in terms of modal excitation functions for both lateral and torsional vibrations. Operational characteristics and conclusions are drawn from the results presented.
Vibration Suppression Using a Constrained Rate-Feedback-Threshold Control Strategy
Authors: Zimmerman D. C. , Inman D. J. , Juang J.-N.
Published: June 2008

A finite time, minimum force rate-feedback-threshold controller is developed to bring a system with or without known external disturbances back into an “allowable” state bound in finite time. The disturbances are assumed to be expandable in terms of Fourier series. The optimal control is defined by a two-point boundary value problem coupled to a set of definite integral constraints. Quasi-closed form solutions are derived which replace the solution of the two-point boundary value problem and definite integral constraints with the solution of algebraic equations and the calculation of matrix exponentials. Examples are provided which demonstrate the threshold control technique and compare the quasi-closed form solutions with numerical and MACSYMA generated exact solutions.
A Global Simulation Model for Hermetic Reciprocating Compressors
Authors: de los Santos M. A. , Cardona S. , Sa´nchez-Reyes J.
Published: June 2008

This article presents a simulation model for reciprocating hermetic compressors. The acoustical behavior of both admission and discharge circuits is analyzed by invoking the discrete element model. Cavities are considered as elastic elements and ducts as rigid elements with inertia according to this model. Reed valves are modeled as systems of three degrees of freedom, and are studied by using modal analysis. The percussive version of Lagrange equations is used to describe the impact between valves and stops or seats. Results from the theoretical model are checked with those experimentally obtained for a real compressor.
A Contribution to Doubly Asymptotic Approximations: An Operator Top-Down Derivation
Authors: Nicolas-Vullierme B.
Published: June 2008

As a contribution to the theory of Doubly Asymptotic Approximations (DAAs), a formal operator top-down derivation specialized to steady-state motions is proposed for the Neumann exterior problem associated to the Helmholtz equation. It generalizes previously published ones which relied either on a modal approach [1] or on a scalar approach for a model problem [2]. The proposed derivation is based on an integral representation of the solution of the Helmholtz equation in an unbounded domain: first, two asymptotic expansions of the representation with respect to the nondimensional wave number k are obtained in the low-k and the high-k ranges; then these expansions are matched. This procedure allows to point out that some geometrical physical and mathematical assumptions underlie the validity of high order continuous forms of the DAAs. Special attention is then devoted to their discretized counterparts which are compared to previously published ones. In both cases it suggests further investigation of some interesting and open geometry and numerical analysis problems.
Modal Analysis of Multiple Eigenvalue Systems by Data Dependent Systems
Authors: Mehta N. P. , Pandit S. M.
Published: June 2008

This note outlines an extension of the Data Dependent Systems (DDS) methodology to the modal analysis of vibratory systems with eigenvalues of arbitrary multiplicity. DDS [1, 2] is a time-series approach to system analysis that combines a rational modeling strategy with elements of linear system theory. The use of an appropriate state-space setting makes it a powerful tool for system identification, and the approach has been successfully applied to the modal characterization of mechanical systems in references [2–4], which provide many examples with real life data.