bluuebunny/crossref_metadata_2025 huggingface dataset:
The Elderly in a Period of Transition
Authors: PETROV IGNAT C.
Published: November 2007

Abstract:  The dramatic changes in overall mode of life experienced since 1989 by the people in Central and Eastern Europe (CEE) provides a good opportunity to study the aging processes and the status of the elderly. In the 1980s, CEE countries were already at an advanced stage of demographic aging of their populations. The first years of the period of transition from totalitarianism to democracy and market economies were marked with an abrupt but varying degree of economic and social deterioration in CEE. This was followed by partial improvement. Earlier, in the late 1960s and 1970s, mortality rates had increased along with a stagnation and decrease of life expectancy in CEE. This contrasted with the steady improvement in the European Union (EU) during the 1970s and 1980s. By 1989, there already was a striking gap in life expectancy between eastern and western Europe, revealing the existence of an East–West health divide. The most important health problems contributing to greater mortality in CEE proved to be cardiovascular and alcohol‐related diseases as well as violence and injury. Suicide rates also were found higher among the (elderly) population in the countries of CEE and Russia compared with the West. The gap was most expressed among the men. The reasons for deterioration in health are complex. There is evidence that negative economic and social changes can lead to psychosocial stress and to unhealthy behaviors. The morale of the elderly people in transition was affected and many‐sided. The Sofia study described here has revealed positive as well as negative personal attitudes toward the changes in life. Feelings of liberation, hope, and new perspectives were reported along with sentiments of disappointment, pessimism, and fear. In sum, transition processes have run unevenly in different countries and have had differing impacts on individuals. Nevertheless, general trends toward improving the economic, psychosocial, and health aspects of the elderly are recently prevailing.
The Science of Healthy Aging
Authors: RATTAN SURESH I. S.
Published: November 2007

Abstract:  Healthy aging and longevity depend on successful and dynamic interactions among biological, psychological, and environmental factors. Biological aging occurs mainly during the period of survival beyond the evolutionarily required essential lifespan (ELS). Natural selection processes for survival and successful reproduction have selected for a range of genetically determined ELS‐assuring maintenance and repair systems (MRSs). The progressive failure of MRSs, and the consequent accumulation of molecular heterogeneity and damage, underlie the biological basis of aging, age‐related diseases, and eventual death. However, the genetic processes of MRSs operate in a complex hierarchy of factors which range from intracellular molecular factors to physiological, psychological, environmental, and other stochastic factors, including chance. This view also facilitates setting up a framework for understanding, researching, and developing effective and realistic strategies for aging intervention, prevention, and therapies. Manipulating genes and the milieu in which genes and gene products operate opens up novel possibilities of aging intervention and prevention. Gene therapy, stem cells, and modulation through functional foods, nutriceuticals, cosmeceuticals and lifestyle alterations, including mild stress‐induced hormesis, are examples of such strategies at various levels of development and practice.
Delaying Dementia and Nursing Home Placement
Authors: McCALLUM JOHN , SIMONS LEON A. , SIMONS JUDITH , FRIEDLANDER YECHIEL
Published: November 2007

Abstract:  In order to capture the “longevity dividend,” modifiable risk factors for a diagnosis of dementia and nursing home placement were examined in a longitudinal study of an elderly cohort living in Dubbo, New South Wales, Australia. One thousand two‐hundred thirty‐three men and 1572 women 60 years and older living in the community were examined in 1988 and followed to 2002 for diagnosis of dementia and nursing home placement. There were 244 (8.7%) nursing home placements and 44% of these placements were primarily due to dementia, but dementia was a secondary diagnosis in another 20% of cases. In a proportional hazards model for dementia, any intake of alcohol predicted a 34% lower risk, and daily gardening a 36% lower risk. Daily walking predicted a 38% lower risk of dementia in men, but there was no significant prediction in women. The lowest tertile of peak expiratory flow predicted an 84% higher risk of dementia, the upper tertile of depression score predicted a 50% higher risk. The Cox proportional hazards model for nursing home placement, showed placement increased significantly with age, urinary incontinence, impaired peak expiratory flow, physical disability, and depression. The hazard of placement was significantly reduced by alcohol intake and female gender. Socioeconomic factors were not significant. Similar risk factors for dementia and nursing home placement indicate that the continuation of moderate alcohol intake, the maintenance of physical activity, especially daily gardening, and improvement of respiratory function, and the treatment of depression are recommended targets for interventions to delay or prevent major negative late‐life experiences.
Alemtuzumab Compared With Chlorambucil As First-Line Therapy for Chronic Lymphocytic Leukemia
Authors: Hillmen Peter , Skotnicki Aleksander B. , Robak Tadeusz , Jaksic Branimir , Dmoszynska Anna , Wu Jingyang , Sirard Cynthia , Mayer Jiri
Published: November 2007

Purpose

We conducted a randomized trial to evaluate the efficacy and safety of intravenous alemtuzumab compared with chlorambucil in first-line treatment of chronic lymphocytic leukemia (CLL).

Patients and Methods

Patients received alemtuzumab (30 mg three times per week, for up to 12 weeks) or chlorambucil (40 mg/m2 every 28 days, for up to 12 months). The primary end point was progression-free survival (PFS). Secondary end points included overall response rate (ORR), complete response (CR), time to alternative therapy, safety, and overall survival.

Results

We randomly assigned 297 patients, 149 to alemtuzumab and 148 to chlorambucil. Alemtuzumab had superior PFS, with a 42% reduction in risk of progression or death (hazard ratio [HR] = 0.58; P = .0001), and a median time to alternative treatment of 23.3 versus 14.7 months for chlorambucil (HR = 0.54; P = .0001). The ORR was 83% with alemtuzumab (24% CR) versus 55% with chlorambucil (2% CR); differences in ORR and CR were highly statistically significant (P < .0001). Elimination of minimal residual disease occurred in 11 of 36 complete responders to alemtuzumab versus none to chlorambucil. Adverse events profiles were similar, except for more infusion-related and cytomegalovirus (CMV) events with alemtuzumab and more nausea and vomiting with chlorambucil. CMV events had no apparent impact on efficacy.

Conclusion

As first-line treatment for patients with CLL, alemtuzumab demonstrated significantly improved PFS, time to alternative treatment, ORR and CR, and minimal residual disease–negative remissions compared with chlorambucil, with predictable and manageable toxicity.
Control of Gastric Acid Secretion in Somatostatin Receptor 2 Deficient Mice: Shift from Endocrine/Paracrine to Neurocrine Pathways
Authors: Zhao Chun-Mei , Martinez Vicente , Piqueras Laura , Wang Lixin , Taché Yvette , Chen Duan
Published: November 2007

The gastrin-enterochromaffin-like (ECL) cell-parietal cell axis is known to play an important role in the regulation of gastric acid secretion. Somatostatin, acting on somatostatin receptor type 2 (SSTR2), interferes with this axis by suppressing the activity of the gastrin cells, ECL cells, and parietal cells. Surprisingly, however, freely fed SSTR2 knockout mice seem to display normal circulating gastrin concentration and unchanged acid output. In the present study, we compared the control of acid secretion in these mutant mice with that in wild-type mice. In SSTR2 knockout mice, the number of gastrin cells was unchanged; whereas the numbers of somatostatin cells were reduced in the antrum (−55%) and increased in the oxyntic mucosa (35%). The ECL cells displayed a reduced expression of histidine decarboxylase and vesicle monoamine transport type 2 (determined by immunohistochemistry), and an impaired transformation of the granules to secretory vesicles (determined by electron microscopic analysis), suggesting low activity of the ECL cells. These changes were accompanied by an increased expression of galanin receptor type 1 in the oxyntic mucosa. The parietal cells were found to respond to pentagastrin or to vagal stimulation (evoked by pylorus ligation) with increased acid production. In conclusion, the inhibitory galanin-galanin receptor type 1 pathway is up-regulated in the ECL cells, and the direct stimulatory action of gastrin and vagal excitation is enhanced on the parietal cells in SSTR2 knockout mice. We suggest that there is a remodeling of the neuroendocrine mechanisms that regulate acid secretion in these mutant mice.
Divergent Leptin Signaling in Proglucagon Neurons of the Nucleus of the Solitary Tract in Mice and Rats
Authors: Huo Lihong , Gamber Kevin M. , Grill Harvey J. , Bjørbæk Christian
Published: November 2007

The central targets mediating the anorectic and other actions of leptin have yet to be fully identified. Although previous studies focused on the hypothalamus, leptin also acts on neurons in extrahypothalamic sites, including the nucleus of the solitary tract (NTS). Moreover, injection of leptin into the NTS of rats suppresses food intake. Within the central nervous system, glucagon-like peptide (GLP-1), a product of proglucagon, is synthesized almost exclusively in neurons of the NTS. Intracerebroventricular administration of GLP-1 inhibits energy intake, and GLP-1 receptor antagonists attenuate the anorexic effects of leptin in rats. To examine whether NTS proglucagon neurons are directly regulated by leptin, we performed double GLP-1 and phosphorylation of signal transducer and activator of transcription-3 immunohistochemistry on brain sections from ip leptin-treated mice and rats. Leptin induced phosphorylation of signal transducer and activator of transcription-3 in 100% of GLP-1 cells in the caudal brainstem of mice. In striking contrast, 0% of GLP-1-positive neurons in rats responded to leptin. We then measured regulation of NTS proglucagon mRNA using real-time RT-PCR in mice and rats fed ad libitum, fasted, or fasted and treated ip with leptin. In mice, proglucagon mRNA fell by fasting, and this was prevented by leptin administration. In rats, by contrast, proglucagon mRNA was unaffected by either fasting or leptin. Taken together, our studies reveal direct regulation of proglucagon neurons by leptin in mice but not rats along with corresponding species differences in the regulation of proglucagon mRNA expression. These data, combined with previous results, suggest a different mechanism of interaction between leptin and NTS proglucagon neurons in mice and rats.
Selective Estrogen Receptor Modulators Accelerate Cutaneous Wound Healing in Ovariectomized Female Mice
Authors: Hardman Matthew J. , Emmerson Elaine , Campbell Laura , Ashcroft Gillian S.
Published: November 2007

A lack of systemic hormones in elderly postmenopausal women leads to delayed cutaneous wound healing. This effect can be reversed by systemic or topical estrogen replacement in both humans and rodent models. Over recent years selective estrogen receptor modulators have been developed in an attempt to achieve the beneficial effects of estrogen clinically, while minimizing the detrimental side effects. The effects of selective estrogen receptor modulators on the skin are poorly understood, and the effects on wound healing have not been assessed. In this study we treated 10-wk-old ovariectomized mice with estradiol, tamoxifen (TAM), raloxifene (RAL), or vehicle and examined the effect on healing of full-thickness incisional wounds. Both TAM and RAL substantially accelerate healing, associated with a dampened inflammatory response and altered inflammatory cytokine profile. In vitro TAM and RAL demonstrate antiinflammatory activity comparable to estrogen. These results have significant implications for the clinical modulation of wound healing.
Pituitary-Specific Knockout of the Carney Complex Gene Prkar1a Leads to Pituitary Tumorigenesis
Authors: Yin Zhirong , Williams-Simons Lisa , Parlow A. F. , Asa Sylvia , Lawrence S. Lawrence S.
Published: November 2007

Carney complex (CNC) is an inherited neoplasia syndrome characterized by spotty skin pigmentation, myxomas, endocrine tumors, and schwannomas. Among the endocrine tumors that comprise the syndrome, GH-producing pituitary tumors are seen in approximately 10% of patients, although biochemical abnormalities of the GH axis are much more common. To explore the role of loss of the CNC gene PRKAR1A on pituitary tumorigenesis, we produced a tissue-specific knockout (KO) of this gene in the mouse. For these studies, we generated a mouse line expressing the cre recombinase in pituitary cells using the rat GHRH receptor promoter. These mice were then crossed with Prkar1a conditional null animals to produce tissue-specific KOs. Although prolactinomas were observed in KO and control mice, the KO mice exhibited a significantly increased frequency of pituitary tumors compared with wild-type or conventional Prkar1a+/− mice. Characterization of the tumors demonstrated they were composed of cells of the Pit1 lineage that stained for GH, prolactin, and TSH. At the biochemical level, levels of GH in the serum of KO animals were markedly elevated compared with controls, regardless of the presence of a frank tumor. These data indicate that complete loss of Prkar1a is sufficient to allow the formation of pituitary tumors and abnormalities of the GH axis, in close analogy to human patients with CNC.
Combinatorial Roles of Protein Kinase A, Ets2, and 3′,5′-Cyclic-Adenosine Monophosphate Response Element-Binding Protein-Binding Protein/p300 in the Transcriptional Control of Interferon-τ Expression in a Trophoblast Cell Line
Authors: Das Padmalaya , Ezashi Toshihiko , Gupta Rangan , Roberts R. Michael
Published: November 2007

In ruminants, conceptus interferon-τ (IFNT) production is necessary for maintenance of pregnancy. We examined the role of protein kinase A (PKA) in regulating IFNT expression through the activation of Ets2 in JAr choriocarcinoma cells. Although overexpression of the catalytic subunit of PKA or the addition of 8-bromo-cAMP had little ability to up-regulate boIFNT1 reporter constructs on their own, coexpression with Ets2 led to a large increase in gene expression. Progressive truncation of reporter constructs indicated that the site of PKA/Ets2 responsiveness lay in a region of the promoter between −126 and −67, which lacks a cAMP response element but contains the functional Ets2-binding site and an activator protein 1 (AP1) site. Specific mutation of the former reduced the PKA/Ets2 effects by more than 98%, whereas mutation of an AP1-binding site adjacent to the Ets2 site or pharmacological inhibition of MAPK kinase 2 led to a doubling of the combined Ets2/PKA effects, suggesting there is antagonism between the Ras/MAPK pathway and the PKA signal transduction pathway. Although Ets2 is not a substrate for PKA, lowering the effective concentrations of the coactivators, cAMP response element-binding protein-binding protein (CBP)/p300, known PKA targets, reduced the ability of PKA to synergize with Ets2, suggesting that PKA effects on IFNT regulation might be mediated through CBP/p300 coactivation, particularly as CBP and Ets2 occupy the proximal promoter region of IFNT in bovine trophoblast CT-1 cells. The up-regulation of IFNT in the elongating bovine conceptus is likely due to the combinatorial effects of PKA, Ets2, and CBP/p300 and triggered via growth factors released from maternal endometrium.
Interplay of Nuclear Factor-κB and B-myb in the Negative Regulation of Androgen Receptor Expression by Tumor Necrosis Factor α
Authors: Ko Soyoung , Shi Liheng , Kim Soyoung , Song Chung S. , Chatterjee Bandana
Published: November 2007

Increased androgen receptor (AR) levels are associated with prostate cancer progression to androgen independence and therapy resistance. Evidence has suggested that chronic inflammation is closely linked to various cancers including prostate cancer. Herein we show that the proinflammatory cytokine TNFα negatively regulates AR mRNA and protein expression and reduces androgen sensitivity in androgen-dependent LNCaP human prostate cancer cells. Decreased AR expression results from transcription repression involving essential in cis interaction of nuclear factor-κB (NF-κB) with the B-myb transcription factor at a composite genomic element in the 5′-untranslated region of AR. The negative regulation was abrogated when NF-κB activity was inhibited by a superrepressor of the inhibitory κB protein. In contrast, androgen-independent C4-2 (LNCaP-derived) cells fail to show AR down-regulation by TNFα, despite expression of B-myb and TNFα-induced NF-κB activity similar to that in LNCaP cells. The negatively regulated AR gene chromatin region showed TNFα-dependent enrichment of B-myb and the NF-κB proteins p65 and p50. In parallel, the histone deacetylase 1, corepressor silencing mediator of retinoid and thyroid hormone receptor and the corepressor-associated scaffold protein mSin3A were recruited to the inhibitory site. In C4-2 cells, neither NF-κB and B-myb, nor any of the corepressor components, were detected at the negative site in response to TNFα. Apoptosis was induced in TNFα-treated LNCaP cells, likely in part due to the down-regulation of AR. The androgen-independent, AR-expressing C4-2 and C4-2B (derived from C4-2) cells were resistant to TNFα-induced apoptosis. The results linking androgen dependence to the NF-κB and AR pathways may be insightful in identifying novel treatment targets for prostate cancer.
Prolactin Signaling through the Short Form of Its Receptor Represses Forkhead Transcription Factor FOXO3 and Its Target Gene Galt Causing a Severe Ovarian Defect
Authors: Halperin Julia , Devi Sangeeta Y. , Elizur Shai , Stocco Carlos , Shehu Aurora , Rebourcet Diane , Unterman Terry G. , Leslie Nancy D. , Le Jamie , Binart Nadine , Gibori Geula
Published: November 2007

Prolactin (PRL) is a hormone with over 300 biological activities. Although the signaling pathway downstream of the long form of its receptor (RL) has been well characterized, little is known about PRL actions upon activation of the short form (RS). Here, we show that mice expressing only RS exhibit an ovarian phenotype of accelerated follicular recruitment followed by massive follicular death leading to premature ovarian failure. Consequently, RS-expressing ovaries of young adults are depleted of functional follicles and formed mostly by interstitium. We also show that activation of RS represses the expression of the transcription factor Forkhead box O3 (FOXO3) and that of the enzyme galactose-1-phosphate uridyltransferase (Galt), two proteins known to be essential for normal follicular development. Our finding that FOXO3 regulates the expression of Galt and enhances its transcriptional activity indicates that it is the repression of FOXO3 by PRL acting through RS that prevents Galt expression in the ovary and causes follicular death. Coexpression of RL with RS prevents PRL inhibition of Galt, and the ovarian defect is no longer seen in RS transgenic mice that coexpress RL, suggesting that RL prevents RS-induced ovarian impairment. In summary, we show that PRL signals through RS and causes, in the absence of RL, a severe ovarian pathology by repressing the expression of FOXO3 and that of its target gene Galt. We also provide evidence of a link between the premature ovarian failure seen in mice expressing RS and in mice with FOXO3 gene deletion as well as in human with Galt mutation.
Flight performance in night-flying sweat bees suffers at low light levels
Authors: Theobald Jamie Carroll , Coates Melissa M. , Wcislo William T. , Warrant Eric J.
Published: November 2007

The sweat bee Megalopta (Hymenoptera: Halictidae), unlike most bees, flies in extremely dim light. And although nocturnal insects are often equipped with superposition eyes, which greatly enhance light capture, Megalopta performs visually guided flight with apposition eyes. We examined how light limits Megalopta's flight behavior by measuring flight times and corresponding light levels and comparing them with flight trajectories upon return to the nest. We found the average time to land increased in dim light, an effect due not to slow approaches, but to circuitous approaches. Some landings, however, were quite fast even in the dark. To explain this, we examined the flight trajectories and found that in dim light, landings became increasingly error prone and erratic, consistent with repeated landing attempts. These data agree well with the premise that Megalopta uses visual summation, sacrificing acuity in order to see and fly at the very dimmest light intensities that its visual system allows.
An antidiuretic peptide (Tenmo-ADFb) with kinin-like diuretic activity on Malpighian tubules of the house cricket, Acheta domesticus (L.)
Authors: Coast Geoffrey M. , Nachman Ronald J. , Schooley David A.
Published: November 2007

Acheta domesticus is reported to have an antidiuretic hormone that reduces Malpighian tubule secretion. Identified peptides known to work in this way (Tenmo-ADFa and ADFb, and Manse-CAP2b) were tested as candidates for the unidentified hormone, along with their second messenger,cyclic GMP. Only Tenmo-ADFb was active, but was diuretic, as was 8-bromo cyclic GMP. The activity of Tenmo-ADFb is comparable to that of the cricket kinin neuropeptide, Achdo-KII, but it is much less potent. Its activity was unaffected by deleting either the six N-terminal residues or the C-terminal phenylalanine.

At high concentrations, tubule secretion is doubled by Tenmo-ADFb and Achdo-KII, but their actions are non-additive, suggesting they have a similar mode of action. Both stimulate a non-selective KCl and NaCl diuresis, which is consistent with the opening of a transepithelial Cl–conductance. In support of this, the diuretic response to Tenmo-ADFb and Achdo-KII is prevented by a ten-fold reduction in bathing fluid chloride concentration, and both peptides cause the lumen-positive transepithelial voltage to collapse. The Cl– conductance pathway appears likely to be transcellular, because the Cl– channel blocker DPC reduces both basal and peptide-stimulated rates of secretion. The effects of 8-bromo cyclic GMP on transepithelial voltage and composition of the secreted fluid are markedly different from those of Tenmo-ADFb.

This is the first report of the antidiuretic factor Tenmo-ADFb stimulating tubule secretion. Although the actions of Tenmo-ADFb are indistinguishable from those of Achdo-KII, it is unlikely to act at a kinin receptor, because the core sequence (residues 7–12) lacks the Phe and Trp residues that are critical for kinin activity.
Temperature and food mediate long-term thermotactic behavioral plasticity by association-independent mechanisms in C. elegans
Authors: Chi Cynthia A. , Clark Damon A. , Lee Stella , Biron David , Luo Linjiao , Gabel Christopher V. , Brown Jeffrey , Sengupta Piali , Samuel Aravinthan D. T.
Published: November 2007

Thermotactic behavior in the nematode Caenorhabditis elegansexhibits long-term plasticity. On a spatial thermal gradient, C. elegans tracks isotherms near a remembered set-point(TS) corresponding to its previous cultivation temperature. When navigating at temperatures above its set-point(T>TS), C. elegans crawls down spatial thermal gradients towards the TS in what is called cryophilic movement. The TS retains plasticity in the adult stage and is reset by ∼4 h of sustained exposure to a new temperature. Long-term plasticity in C. elegans thermotactic behavior has been proposed to represent an associative learning of specific temperatures conditioned in the presence or absence of bacterial food. Here,we use quantitative behavioral assays to define the temperature and food-dependent determinants of long-term plasticity in the different modes of thermotactic behavior. Under our experimental conditions, we find that starvation at a specific temperature neither disrupts TSresetting toward the starvation temperature nor induces learned avoidance of the starvation temperature. We find that prolonged starvation suppresses the cryophilic mode of thermotactic behavior. The hen-1 and tax-6 genes have been reported to affect associative learning between temperature and food-dependent cues. Under our experimental conditions,mutation in the hen-1 gene, which encodes a secreted protein with an LDL receptor motif, does not significantly affect thermotactic behavior or long-term plasticity. Mutation in the tax-6 calcineurin gene abolishes thermotactic behavior altogether. In summary, we do not find evidence that long-term plasticity requires association between temperature and the presence or absence of bacterial food.
Morphology and kinematics of feeding in hagfish: possible functional advantages of jaws
Authors: Clark Andrew J. , Summers Adam P.
Published: November 2007

As in gnathostomes, the hagfish feeding apparatus includes skeletal, dental and muscular components. In the present study, we examined feeding morphology and kinematics in two hagfish species, Eptatretus stoutii and Myxine glutinosa, representing the two major hagfish lineages. E. stoutii have larger dental plates, larger basal plates, and stronger clavatus muscles (the major dental plate retractor) than M. glutinosa. Despite morphological differences, kinematic profiles are similar in E. stoutii and M. glutinosa. When protracted, the dental plate unfolds and exposes keratinous teeth, which are then embedded in the prey. Once food is grasped, the dental plate is retracted into the mouth. During retraction, the clavatus muscle can generate up to 16 N of force, which exceeds the bite force of some gnathostomes of similar size. In addition to producing high forces with the feeding muscles, hagfish can evert their dental plates to 180°, exceeding the gape angles attained by virtually all gnathostomes, suggesting vertebrate jaws are not the prerequisites for muscle force generation and wide gapes. We propose that dental plate protraction and retraction can be modeled as a fixed pulley that lacks the speed amplification occurring in gnathostome jaws. Hagfish gape cycle times are approximately 1 s,and are longer than those of gnathostomes, suggesting that a functional advantage of jaws is the speed that allows gnathostomes to exploit elusive prey.
Protein kinase C is an important signaling mediator associated with motility of intact sea urchin spermatozoa
Authors: White Daniel , de Lamirande Eve , Gagnon Claude
Published: November 2007

Numerous kinases and phosphatases are most likely implicated in sperm motility initiation and maintenance. Data on these signaling molecules were mostly obtained from studies conducted on in vitrodemembranated–reactivated sperm models but are not necessarily representative of the in vivo situation. We therefore investigated the effect of a variety of cell-permeable chemicals, mostly kinase inhibitors,on the motility initiation and maintenance of intact sea urchin spermatozoa. Among the 20 substances tested, the protein kinase C (PKC) inhibitor chelerythrine was the most potent, arresting motility at concentrations starting from 1.5–2 μmol l–1. Motility was also inhibited by two other PKC inhibitors as well as staurosporine. Furthermore,these inhibitors prevented the motility-associated increase in phosphorylation of at least four PKC substrates. These phospho-PKC target proteins, as assessed with an antibody specific to phosphorylated motifs of PKC substrates,were found to be associated with the flagellum, either in the Triton X-100 soluble portion or the axoneme (Triton X-100 insoluble). A phosphorylated PKC-like enzyme was also detected by immunoblotting in the flagellum, as well as a significant 50 kDa PKC cleavage product. Taken together, the data strongly indicate for the first time that, in vivo, which means on intact spermatozoa, PKC is a key signaling mediator associated with the maintenance of sea urchin sperm motility.
Lung ventilation contributes to vertical lymph movement in anurans
Authors: Hedrick Michael S. , Drewes Robert C. , Hillman Stanley S. , Withers Philip C.
Published: November 2007

Anurans (frogs and toads) generate lymphatic fluid at 10 times the rate in mammals, largely as a consequence of their very `leaky' vasculature and high interstitial compliance. Lymph is ultimately pumped into the venous system by paired, dorsally located lymph hearts. At present, it is unclear how lymphatic fluid that accumulates in central body subcutaneous lymph sacs is moved to the anterior and posterior lymph hearts in the axillary regions and how lymph is moved, against gravity, to the dorsally located lymph hearts. In this study,we tested the hypothesis that lung ventilation, through its consequent effects on lymph sac pressure, contributes to the vertical movement of lymphatic fluid in the cane toad (Chaunus marinus) and the North American bullfrog(Lithobates catesbeiana). We measured pressure in the dorsal, lateral and subvertebral lymph sacs of anesthetized cane toads and bullfrogs during artificial lung inflation and deflation. We also measured pressure in the subvertebral lymph sac, which adheres to the dorsal surface of the lungs,simultaneously with brachial (forelimb) and pubic (posterior) sac pressure during ventilation in freely behaving animals. There were highly significant(P<0.001) relationships between lung pressure and lymph sac pressures (r2=0.19–0.72), indicating that pulmonary pressure is transmitted to the highly compliant lymph sacs that surround the lungs. Subvertebral sac pressure of resting animals was not significantly different between L. catesbeiana (518±282 Pa) and C. marinus (459±111 Pa). Brachial sac compliance (ml kPa–1 kg–1) also did not differ between the two species (33.6±5.0 in L. catesbeiana and 37.0±9.4 in C. marinus). During expiration (lung deflation), reductions in expanding subvertebral sac pressure are communicated to the brachial lymph sac. Changes in brachial and pubic lymph sac pressures were correlated almost entirely during expiration rather than inspiration. The change in brachial sac pressure during expiration was 235±43 Pa for C. marinus and 215±50 Pa for L. catesbeiana, which is of sufficient magnitude to move lymph the estimated 0.5–1.0 cm vertical distance from the forelimb to the vicinity of the anterior lymph hearts. We suggest that lymph is moved during expiration to the subvertebral sac from anterior and posterior lymph sacs. During lung inflation, increased lymph sac pressure moves lymph to axillary regions, where lymph hearts can return lymph to the vascular space. Consequently, pulmonary ventilation has an important role for lymph movement and, hence, blood volume regulation in anurans.
Comparative thyroidology: thyroid gland location and iodothyronine dynamics in Mozambique tilapia (Oreochromis mossambicus Peters) and common carp (Cyprinus carpio L.)
Authors: Geven Edwin J. W. , Nguyen Nha-Khanh , van den Boogaart Marcel , Spanings F. A. Tom , Flik Gert , Klaren Peter H. M.
Published: November 2007

In teleosts, the thyroid gland is mostly found in the subpharyngeal region. However, in several species thyroid follicles are found in, for example,heart, head kidney and kidney. Such heterotopic thyroid follicles are active,and considered to work in concert with the subpharyngeal thyroid. In Mozambique tilapia (Oreochromis mossambicus) thyroid activity is,indeed, restricted to the subpharyngeal region; in common carp (Cyprinus carpio) the functional endocrine thyroid is associated with renal tissues. The subpharyngeal follicles of carp comprise only 10% of the total thyroid tissue, and these follicles neither accumulate iodide nor synthesize or secrete thyroid hormones to a significant degree. Although the shape and size of carp subpharyngeal and renal follicles vary, the epithelial cell height of the thyrocytes and thyroxine immunoreactivity do not differ, which suggests that the activity of the carp subpharyngeal thyroid follicles is dormant. Differences in thyroid physiology between the two fish species were further assessed at the level of peripheral thyroid hormone metabolism. Carp clears plasma of thyroid hormones faster than tilapia does. Furthermore, a significant amount of conjugated thyroid hormones was observed in the plasma of tilapia, which was preceded by the occurrence of thyroid hormone conjugates in the subpharyngeal region and coincides with the appearance of conjugates in the surrounding water. Apparently, plasma thyroid hormone conjugates in tilapia originate from the thyroid gland and function in the excretion of thyroid hormones. Our data illustrate the variability in teleostean thyroidology, an important notion for those studying thyroid physiology.
Mudskippers brood their eggs in air but submerge them for hatching
Authors: Ishimatsu Atsushi , Yoshida Yu , Itoki Naoko , Takeda Tatsusuke , Lee Heather J. , Graham Jeffrey B.
Published: November 2007

Intertidal mudflats are highly productive ecosystems that impose severe environmental challenges on their occupants due to tidal oscillations and extreme shifts in habitat conditions. Reproduction on mudflats requires protection of developing eggs from thermal and salinity extremes,O2 shortage, dislodgement by currents, siltation and predation. Mudskippers are air-breathing, amphibious fishes, and one of few vertebrates that reside on mudflats. They lay their eggs in mud burrows containing extremely hypoxic water, raising the question of how the eggs survive. We found that the Japanese mudskipper Periophthalmus modestus deposits its eggs on the walls of an air-filled chamber within its burrow. To ensure adequate O2 for egg development, the burrow-guarding male mudskipper deposits mouthfuls of fresh air into the egg chamber during each low tide, a behaviour that can be upregulated by egg-chamber hypoxia. When egg development is complete the male, on a nocturnal rising tide, removes the egg-chamber air and releases it outside the burrow. This floods the egg chamber and induces egg hatching. Thus, P. modestus has developed a reproductive strategy that allows it to nurture eggs in this severe habitat rather than migrating away from the mudflat. This requires that mudskipper eggs be specialized to develop in air and that the air-breathing capacity of the egg-guarding male be integrated in a complex behavioural repertoire that includes egg guarding, ferrying air to and from the egg chamber, and sensing O2 levels therein, all in concert with the tidal cycle.
A combustion model sensitivity study for CH4/H2 bluff-body stabilized flame
Authors: Hossain M , Malalasekera W
Published: November 2007

The objective of the current work is to assess the performance of different combustion models in predicting turbulent non-premixed combustion in conjunction with the k-∊ turbulence model. The laminar flamelet, equilibrium chemistry, constrained equilibrium chemistry, and flame sheet models are applied to simulate combustion in a CH4/H2 bluff-body flame experimentally studied by the University of Sydney. The computational results are compared to experimental values of mixture fraction, temperature, and constituent mass fractions. The comparison shows that the laminar flamelet model performs better than other combustion models and mimics most of the significant features of the bluff-body flame.
Effect of electrolyte on the current-carrying process in electrochemical machining
Authors: Mukherjee S K , Kumar S , Srivastava P K
Published: November 2007

Role of electrolyte [NaCl] in current-carrying processes in electrochemical machining of iron work piece has been analysed in light of Onsagar equation of strong electrolyte. Over-voltage-calculated with respect to equilibrium gap and penetration rate, shows that only a narrow range of equilibrium gap and penetration rate are admissible. It has been found that the maximum specific conductance of NaCl solution is 0.0387 ohm-1 cm-1 at 1.5 M NaCl concentration. It appears that NaCl contribute only a fraction of current, on the other hand H+ and OH-produced by electrolysis of water play an important role in the current-carrying process.
Optimal active random vibration control for smart truss structures based on reliability
Authors: Gao W , Zhang N
Published: November 2007

The current paper presents the reliability-based optimization of the location and feedback gains of active bar in a closed-loop control system for random smart truss structures under stationary random excitation. The mathematical model with reliability constraints on the root mean square value of the structural random dynamic displacement and stress response is developed based on maximization of dissipation energy due to the control action. The randomness of the structural physical materials, geometry, and damping are included in the analysis, and the applied forces are considered as stationary random excitation. The numerical characteristic corresponding to mean values and standard deviations of the stationary random responses of random smart structures is developed by the random factor method. Numerical examples of truss structures are presented to demonstrate the rationality and validity of the active control model.
Non-symmetrical plane contact of a wedge indenter
Authors: Shahani A R , Adibnazari S , Naderi D
Published: November 2007

Asymmetric contact problem of an elastic wedge and an elastic half-plane has been considered. Contact pressure distributions as well as the lengths of the contact zones are extracted analytically. The results have been compared with the results of the symmetric problem and also the FE modelling of the problem which show excellent agreement. The method of approach is a completely analytical method based on the singular integral equations. In this method, the boundary conditions of the problem are stated as some singular integrals and distribution of the contact pressure is determined. Then, with the aid of the equilibrium equations and the consistency conditions of the singular integral solution, the lengths of the contact zones are extracted. Finally, using the Muskhelishvili potential function and Legendre polynomials, a new method for calculating stress field has been established. It is shown that application of Legendre polynomials is simpler than Chebyshev polynomials which have been used widely in the previous researches.
An adaptive algorithm for compressible reacting flows using interpolating wavelets
Authors: Prosser R
Published: November 2007

A new wavelet-based method for the simulation of reacting flows on adaptive meshes is presented. The method is based on the removal of grid points whose wavelet coefficients are small with reference to some user-specified threshold. Unlike some other collocation methods, the scheme simulates flow behaviour in the physical (i.e. not transformed) domain, and the wavelets, thus, provide the method by which the derivatives appearing in the transport equations are calculated. The wavelet transformis based on a subtraction algorithm, and circumvents the hanging node problem associated with other adaptive strategies. Interpolating wavelets are applied to a compressible one-dimensional laminar flame problem with time dependent boundary conditions. We find that the resolution of the chemistry distribution is comparatively straightforward. The same is not true of the pressure field, which demonstrates sensitivity to the imposed threshold level. Conclusions and directions for future work are presented based on these findings.
A computational method for cavitational flows based on energy conservation
Authors: Huang Diangui , Zhuang Yueqing , Cai Ruizhong
Published: November 2007

In flow with cavitations, incompressible liquid and compressible vapour coexist. Phase transition in the flow results in complex thermophysical processes. The flow field is discontinuous with density varying greatly near the bubble wall. Existing computational fluid dynamics (CFD) methods cannot simulate this complex physical phenomenon accurately. In the current paper, based on primitive variables, namely pressure, velocity, and enthalpy, a new preconditioning method specifically dealing with the unsteady flow field with cavitation is established. The fundamental equations, which adopt the energy equation instead of the conventional cavitation model, are discretized using Roe's scheme to capture the discontinuous surface. A divisional computational method of state parameters for H2O, based on pressure and enthalpy, is constructed. It can be applied to liquid region, saturation region and vapour region. The examples indicate that this method can be used to capture the unsteady cavity in the flow field.
Clustering techniques and their applications in engineering
Authors: Pham D T , Afify A A
Published: November 2007

Clustering is an important data exploration technique with many applications in different areas of engineering, including engineering design, manufacturing system design, quality assurance, production planning and process planning, modelling, monitoring, and control. The clustering problem has been addressed by researchers from many disciplines. However, efforts to perform effective and efficient clustering on large data sets only started in recent years with the emergence of data mining. The current paper presents an overview of clustering algorithms from a data mining perspective. Attention is paid to techniques of scaling up these algorithms to handle large data sets. The paper also describes a number of engineering applications to illustrate the potential of clustering algorithms as a tool for handling complex real-world problems.
A wavelet cluster-based band-pass filtering and envelope demodulation approach with application to fault diagnosis in a dry vacuum pump
Authors: Jiang W , Spurgeon S K , Twiddle J A , Schlindwein F S , Feng Y , Thanagasundram S
Published: November 2007

A Morlet-like wavelet cluster-based method for band-pass filtering and envelope demodulation is described. Via appropriate choice of wavelet parameters, a wavelet cluster combined with multi-Morlet-like wavelets can be used as a band-pass filter with zero phase shift, flat topped pass-band and rapid attenuation in the transition band. It can be used to extract high frequency natural vibration components. The imaginary part of the Morlet-like wavelet cluster is the Hilbert transformation of its real part. This can be used to implement envelope demodulation and extract the envelope component of the high frequency resonance band. The method is applied for fault diagnosis relating to bearing defects in a dry vacuum pump. It is shown that the fault characteristic frequencies can be extracted effectively. The efficacy of the method is demonstrated in experimental studies.
Investigation of the failure of a liquid crystal display panel under mechanical shock
Authors: Kwon S , Lee B Y , Park S H
Published: November 2007

A new method linking experimental and theoretical approaches is proposed to precisely analyse the failure of liquid crystal display (LCD) panels under mechanical drop. Generally, the thickness of a glass plate for LCD panel is less than 0.7 mm, and thus requires sufficient strength to withstand mechanical shock. In the present work, the fracture toughness ( KIC) of panel glass obtained experimentally is compared with the stress-intensity factor ( KI) calculated using the maximum stress at weak points via a finite-element drop simulation in order to evaluate crack growth on the panel. It is demonstrated that this approach is simple but effective to determine the specification of components at the design level, including the roughness of glass panel edges. Furthermore, from a dynamic simulation, important information related to the shockproof design of an LCD panel is gathered.
Improvement on acoustic performance of the accumulator of double-cylinder rotary compressors
Authors: Huang Z Y , Jiang W K , Liu C H , Jin H S , Zhou Y
Published: November 2007

Since the accumulator is one of main contributors to the overall noise level of the rotary compressor, research on the acoustic performance of accumulators is essential. Numerical analysis based on the computational fluid dynamic method shows that large pressure fluctuations are caused mainly by periodic rotating piston. The idea that the flow phase differences of two pipes could be utilized for suppressing fluctuations is proposed. The double standpipes of an accumulator are changed to the single pipe with two branches and each branch is connected to the inlet of the compressor. Flow structures and wall pressure fluctuations for the two configurations are computed. Computational results show that wall pressure pulsations of the new accumulator are obviously lower than that of the original. The acoustic experiments were carried out under the real working conditions. Compared with the original, the new accumulator shows that the overall noise level is reduced about 1.2 dB(A) and the sound spectrum levels are also lower in a wide frequency domain, which validate the numerical and theoretical analysis.
Computation of aerodynamic noise of centrifugal fan using large eddy simulation approach, acoustic analogy, and vortex sound theory
Authors: Liu Q , Qi D , Tang H
Published: November 2007

Large eddy simulation is applied to solve the unsteady three-dimensional viscous flow in the whole impeller-volute configuration of a centrifugal fan. The results of the simulation are used to predict the impeller-volute interaction and to obtain the unsteady pressure, velocity, and vorticity fluctuations in the impeller and volute casing. The simulation at the design point is carried out with the wall-adapting local eddy-viscosity subgrid-scale model and a sliding mesh technique is applied to consider the impeller-volute interaction. The results show that a strongly unsteady flow field occurs in the impeller and volute casing of the fan, and the flow is characterized with obvious pressure and vorticity fluctuations, especially at the tongue and at the blade wake region. The large pressure fluctuation at the tongue and the large fluctuation of the blade wake vorticity appear as the blade wake is passing the tongue. Acoustic analogy and vortex sound theory are used to compute the radiated dipole and quadrupole sound fields, which are in good agreement with the experiment. The sound results show that the vortex sound theory is convenient for the broadband noise computation, and the dipole sound is much higher than the quadrupole sound. The dipoles, distributed over the volute tongue surface, are the dominant sound source of the fan.
Analysis and characterization of the behaviour of a variable geometry structure
Authors: MacAreno L M , Angulo C , López D , Agirrebeitia J
Published: November 2007

The study about a variable geometry truss is presented. The first step is a kinematic design and later an analysis using the MSC/Adams code. Then, the finite-element method with the MSC/Nastran code was used to develop a variable mathematical model to characterize its mechanical behaviour. An explanation is given of the solution selected to analyse the most complex joints. A series of measurements were carried out using different experimental techniques. The aim of photogrammetry tests is to study clearance effect in the joints. On the other hand, measurements of the stiffness were carried out to introduce these data in the finite-element model and thus characterize the accurate position of the structure.