bluuebunny/crossref_metadata_2025 huggingface dataset:
Polarization and apoptosis of T cell subsets in idiopathic thrombocytopenic purpura
Authors: CHANG‐LIN W. U. , JIAN‐CHENG X. U. E. , FANG L. I. U. , HONG X. I. A. O. , XUE‐MIN Z. H. U. O. , QUN C. H. E. N. , XUE‐WEN L. V.
Published: May 2007

It is well known that idiopathic thrombocytopenic purpura (ITP) is an acquired organ‐specific autoimmune hemorrhagic disease and dysfunctional cellular immunity is considered important in the pathophysiology of ITP, however, polarization and apoptosis profiles of T lymphocytes remain unclear completely. In this paper, we investigated the polarization of T cell subsets, the expressions of apoptotic proteins Fas/FasL on T cell subsets and the level of antiapoptotic gene bcl‐2 and bax mRNA in the bcl‐2 family, then discussed the role of them in ITP pathogenesis. We demonstrated that the ratios of Th1/Th2 and Tc1/Tc2 in ITP children increased obviously, the average percentages of Th1 and Th2 also increased clearly, but the average percentages of Tc1 and Tc2 did not changed. In ITP children, the expressions of Fas, FasL on Th, Th1, Th2, Tc, Tc1 and Tc2 increased significantly. The expressions of FasL on Th1 and Tc1 increased sharply vs. Fas, whereas the expressions of Fas on Th2 and Tc2 increased obviously vs. FasL. The expressions of bcl‐2 mRNA in ITP children increased significantly, but the expressions of bax mRNA decreased, the ratios of bcl‐2/bax mRNA were improved obviously and there were positive correlation between the ratios of Th1/Th2 (IFN‐γ+T/IL‐4+T) and the ratios of bcl‐2/bax mRNA. Taken together, our findings indicate that ITP is Th1 type cell predominant disease although the precise mechanisms await further functional assay. This abnormal polarization of T cell subsets might be related to the high ratios of bcl‐2/bax mRNA and the abnormal expressions of Fas, FasL on T cell subsets, as can involve in ITP immunopathogenesis.
Lipid profile inβ‐thalassemia intermedia patients: correlation with erythroid bone marrow activity
Authors: AMENDOLA G. , DANISE P. , TODISCO N. , D'URZO G. , DI PALMA A. , DI CONCILIO R.
Published: May 2007

Lipid abnormalities, including low levels of all fractions of serum lipids, have been repeatedly reported in all phenotypes ofβ‐thalassemia. Unexpectedly, in more recent studies, the concentration of total cholesterol (TC) and high‐ and/or low‐density lipoprotein cholesterol (HDL‐C and LDL‐C) has been found inβ‐thalassemia intermedia (TI) patients even lower than in thalassemia major, without a clear explanation of pathophysiology of these findings. This lack of information prompted us to evaluate the plasma lipids and lipoproteins pattern in the TI patients followed in our department; the data were compared with those found in hereditary spherocytosis patients. Furthermore, in both groups of patients, the erythroid bone marrow activity was evaluated, utilizing the level of soluble transferrin receptors (sTfR) in the plasma. Both groups of patients showed similar lipid abnormalities (low‐TC, HDL‐C and LDL‐C) and the same increase of sTfR, with significantly lower hemoglobin levels in TI patients. Data analysis of our study shows that the lipid profile in TI patients is not influenced by age, sex, liver injury, hemoglobin or ferritin levels; the higher erythroid bone marrow activity with the enhanced cholesterol consumption could be the dominant mechanism implicated in the lipid abnormalities of TI patients.
Rapamycin Reduces CCR5 Density Levels on CD4 T Cells, and This Effect Results in Potentiation of Enfuvirtide (T-20) against R5 Strains of Human Immunodeficiency Virus Type 1 In Vitro
Authors: Heredia Alonso , Gilliam Bruce , Latinovic Olga , Le Nhut , Bamba Douty , DeVico Anthony , Melikyan Gregory B. , Gallo Robert C. , Redfield Robert R.
Published: May 2007

The CCR5 chemokine receptor plays a pivotal role in human immunodeficiency virus type 1 (HIV-1) infection. Several studies have suggested that CCR5 density levels in individuals are rate limiting for infection. In addition, CCR5 density levels influence the antiviral activity of the HIV-1 fusion inhibitor enfuvirtide (T-20) against R5 strains. In the present study we demonstrate that rapamycin (RAPA), a drug approved for the treatment of renal transplantation rejection, reduces CCR5 density levels on CD4 T cells and inhibits R5 HIV-1 replication. In addition, RAPA increased the antiviral activity of T-20 against R5 strains of the virus in a cell-cell fusion assay and as shown by quantification of early products of viral reverse transcription. Median-effect analysis of drug interaction between RAPA and T-20 in infectivity assays using donor peripheral blood mononuclear cells demonstrated that the RAPA-T-20 combination is synergistic against R5 strains of HIV-1 and this synergy translates into T-20 dose reductions of up to ∼33-fold. Importantly, RAPA effects on replication levels and T-20 susceptibility of R5 strains of HIV-1 were observed at drug concentrations that did not inhibit cell proliferation. These results suggest that low concentrations of RAPA may potentiate the antiviral activity of T-20 against R5 strains of HIV-1, which are generally present throughout the course of infection and are less sensitive to T-20 inhibition than are X4 strains.
Identification of Commensal Bacterial Strains That Modulate
Yersinia enterocolitica
and Dextran Sodium Sulfate-Induced Inflammatory Responses: Implications for the Development of Probiotics
Authors: Frick Julia S. , Fink Kerstin , Kahl Frauke , Niemiec Maria J. , Quitadamo Matteo , Schenk Katrin , Autenrieth Ingo B.
Published: May 2007

An increasing body of evidence suggests that probiotic bacteria are effective in the treatment of enteric infections, although the molecular basis of this activity remains elusive. To identify putative probiotics, we tested commensal bacteria in terms of their toxicity, invasiveness, inhibition of
Yersinia
-induced inflammation in vitro and in vivo, and modulation of dextran sodium sulfate (DSS)-induced colitis in mice. The commensal bacteria
Escherichia coli
,
Bifidobacterium adolescentis
,
Bacteroides vulgatus
,
Bacteroides distasonis
, and
Streptococcus salivarius
were screened for adhesion to, invasion of, and toxicity for host epithelial cells (EC), and the strains were tested for their ability to inhibit
Y. enterocolitica
-induced NF-κB activation. Additionally,
B. adolescentis
was administered to mice orally infected with
Y. enterocolitica
and to mice with mucosae impaired by DSS treatment. None of the commensal bacteria tested was toxic for or invaded the EC.
B. adolescentis
,
B. distasonis
,
B. vulgatus
, and
S. salivarius
inhibited the
Y. enterocolitica
-induced NF-κB activation and interleukin-8 production in EC. In line with these findings,
B. adolescentis
-fed mice had significantly lower results for mean pathogen burden in the visceral organs, intestinal tumor necrosis factor alpha mRNA expression, and loss of body weight upon oral infection with
Y. enterocolitica
. In addition, the administration of
B. adolescentis
decelerated inflammation upon DSS treatment in mice. We suggest that our approach might help to identify new probiotics to be used for the treatment of inflammatory and infectious gastrointestinal disorders.
Femoral osteolysis following total hip replacement
Authors: Dattani R
Published: May 2007

Total hip replacement represents the most significant advance in orthopaedic surgery in the 20th century. Periprosthetic osteolysis remains the most significant long-term complication with total hip replacement. It has been reported with all materials and prosthetic devices in use or that have been used to date. This paper reviews the current thinking on the aetiology, pathogenesis, management and future treatment options for osteolysis.
Familial aggregation and excess maternal transmission of type 2 diabetes in Tunisia
Authors: Arfa Imen , Abid Abdelmajid , Malouche Dhafer , Ben Alaya Nissaf , Roland Azegue Théophile , Mannai Imen , Majdi Zorgati Mohamed , Chiheb Ben Rayana Mohamed , Ben Ammar Slim , Blousa-Chabchoub Samira , Ben Romdhane Habiba , Zouari Béchir , Koussay Dellagi Mohamed , Abdelhak Sonia
Published: May 2007

Aim

To evaluate the degree of familial aggregation of type 2 diabetes mellitus in Tunisia and to investigate transmission patterns of the disease and their relationships with patients' clinical profiles.

Methods

Family history of diabetes and clinical data were collected for 132 unrelated type 2 diabetic Tunisian patients. Diabetes status was recorded for first degree relatives (parents, siblings) and second degree relatives (aunts and uncles from both maternal and paternal sides). Information about family history of diabetes was gathered for a total of 1767 individuals.

Results

Familial aggregation of type 2 diabetes was prominent and more important among first degree relatives than among second degree relatives (p = 0.01). Among studied subjects, 70% reported at least one relative with diabetes and 34% had at least one parent with diabetes. Diabetes was more frequent among mothers than fathers of probands (p = 0.03). This maternal effect extends to second degree relatives as diabetes was more common among maternal than paternal aunts and uncles (p = 0.01). There is no significant difference in clinical and metabolic profiles between patients according to transmission patterns of the disease.

Conclusion

These results suggest familial aggregation and excess maternal transmission of type 2 diabetes in the Tunisian studied population.
Morroniside and loganin extracted from Cornus officinalis have protective effects on rat mesangial cell proliferation exposed to advanced glycation end products by preventing oxidative stress
Authors: Xu Huiqin , Shen Jian , Liu Hong , Shi Yan , Li Lihua , Wei Min
Published: May 2007

Advanced glycation end products (AGE) are involved in the alterations of renal mesangial cell (MCs) growth, a feature of early stages of diabetic nephropathy (DN). We postulate that morroniside and loganin, 2 components extracted from Cornus officinalis , may ameliorate the detrimental effects of AGE-induced MCs proliferation by preventing oxidative stress. Rat MCs cultured in AGE milieu were treated with morroniside and loganin. Results showed that morroniside and loganin inhibited AGE-induced MC proliferation as measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Fluorescence microscopy revealed that the morroniside and loganin improved the morphological changes of MCs. Flow cytometric analysis showed that morroniside and loganin inhibited the cell cycle of rat MCs. Furthermore, the level of reactive oxygen species was significantly reduced, and the activities of superoxide dismutase and glutathione peroxidase were markedly increased, whereas the level of malondialdehyde was not significantly reduced. These results suggest that morroniside and loganin regulate MC growth by preventing oxidative stress. Thus, this study provides a molecular basis for the use of morroniside and loganin in the early stages of DN.
Modulatory role of verapamil treatment on the cardiac electrophysiological effects of cisapride
Authors: Morissette Pierre , Hreiche Raymond , Turgeon Jacques
Published: May 2007

The role of transport proteins in the distribution of drugs in various tissues has obvious implications for drug effects. Recent reports indicate that such transporters are present not only in the liver, intestine, or blood−brain barrier but also in the heart. The objective of our study was to determine whether treatment of animals with verapamil, a well-known L-type calcium channel blocker with modulatory properties of membrane transporters, would alter distribution and cardiac electrophysiological effects of an IKrblocker. Male guinea pigs (n = 72) were treated with either saline or verapamil at various doses (1.5 to 15 mg/kg) and for various durations (1 to 7 d). Animals were sacrified 24 h after the last dose of verapamil (or saline), and their hearts were isolated and retroperfused with cisapride, a gastrokinetic drug with IKrblockade properties. In hearts obtained from animals treated with vehicle, 50 nmol/L cisapride prolonged MAPD90by 15 ± 5 ms vs. 36 ± 8 ms in hearts from animals treated with verapamil 15 mg·kg−1·d−1for 5 d (p < 0.01). Treatment effects were dose- and time-dependent. Cardiac myocytes isolated from animals treated with vehicle or verapamil were incubated for 3 h with 100 ng/mL cisapride. Intracellular concentrations of cisapride in cardiac myocytes from animals treated with verapamil were 1.6-fold higher than those measured in myocytes from animals treated with vehicle (p < 0.01). The increase in intracellular concentrations of cisapride and potentiation of cisapride electrophysiological effects suggest that chronic treatment with drugs such as verapamil may modulate drug effects on the QT interval because of an increased access to intracellular binding sites on IKrchannels.
Respiratory motor activity: influence of neuromodulators and implications for sleep disordered breathingThis paper is one of a selection of papers published in this Special Issue, entitled Young Investigators' Forum.
Authors: Horner Richard L.
Published: May 2007

Sleep, especially rapid-eye-movement sleep, causes fundamental modifications of respiratory muscle activity and control mechanisms, modifications that can predispose individuals to sleep-related breathing disorders. One of the most common of these disorders is obstructive sleep apnea (OSA) that affects approximately 4% of adults. OSA is caused by repeated episodes of pharyngeal airway obstruction that can occur hundreds of times per night, leading to recurrent asphyxia, arousals from sleep, daytime sleepiness, and adverse cardiovascular and cerebrovascular consequences. OSA is caused by the effects of sleep on pharyngeal muscle tone in individuals with already narrow upper airways. Moreover, since OSA occurs only in sleep, this disorder by definition is a state-dependent process ultimately caused by the influence of sleep neural mechanisms on the activity of pharyngeal motoneurons. This review synthesizes recent findings relating to control of pharyngeal muscle activity across sleep–wake states, with special emphasis on the influence of neuromodulators acting at the hypoglossal motor nucleus that inervates the genioglossus muscle of the tongue. The results of such basic physiological studies may be relevant to identifying and developing new pharmacological strategies to augment pharyngeal muscle activity in sleep, especially rapid-eye-movement sleep, as potential treatments for OSA.
Regulation and function of homeodomain proteins in the embryonic and adult vascular systemsThis paper is one of a selection of papers published in this Special Issue, entitled Young Investigators' Forum.
Authors: Douville Josette M. , Wigle Jeffrey T.
Published: May 2007

During embryonic development, the cardiovascular system first forms and then gives rise to the lymphatic vascular system. Homeobox genes are essential for both the development of the blood and lymphatic vascular systems, as well as for their maintenance in the adult. These genes all encode proteins that are transcription factors that contain a well conserved DNA binding motif, the homeodomain. It is through the homeodomain that these transcription factors bind to the promoters of target genes and regulate their expression. Although many homeodomain proteins have been found to be expressed within the vascular systems, little is known about their downstream target genes. This review highlights recent advances made in the identification of novel genes downstream of the homeodomain proteins that are necessary for regulating vascular cellular processes such as proliferation, migration, and endothelial tube formation. Factors known to regulate the functions of vascular cells via modulating the expression of homeobox genes will be discussed. We will also review current methods used to identify and characterize downstream target genes of homeodomain proteins.
Smooth muscle molecular mechanics in airway hyperresponsiveness and asthmaThis paper is one of a selection of papers published in this Special Issue, entitled the Young Investigators' Forum.
Authors: Gil Fulvio R. , Lauzon Anne-Marie
Published: May 2007

Asthma is a respiratory disorder characterized by airway inflammation and hyperresponsiveness associated with reversible airway obstruction. The relative contributions of airway hyperresponsiveness and inflammation are still debated, but ultimately, airway narrowing mediated by airway smooth muscle contraction is the final pathway to asthma. Considerable effort has been devoted towards identifying the factors that lead to the airway smooth muscle hypercontractility observed in asthma, and this will be the focus of this review. Airway remodeling has been observed in severe and fatal asthma. However, it is unclear whether remodeling plays a protective role or worsens airway responsiveness. Smooth muscle plasticity is a mechanism likely implicated in asthma, whereby contractile filament rearrangements lead to maximal force production, independent of muscle length. Increased smooth muscle rate of shortening via altered signaling pathways or altered contractile protein expression has been demonstrated in asthma and in numerous models of airway hyperresponsiveness. Increased rate of shortening is implicated in counteracting the relaxing effect of tidal breathing and deep inspirations, thereby creating a contracted airway smooth muscle steady-state. Further studies are therefore required to understand the numerous mechanisms leading to the airway hyperresponsiveness observed in asthma as well as their multiple interactions.
Insulin-like growth factor type-1 receptor transactivation in vasoactive peptide and oxidant-induced signaling pathways in vascular smooth muscle cellsThis paper is one of a selection of papers published in this Special Issue, entitled Young Investigators' Forum.
Authors: Azar Zeina M. , Mehdi Mohamad Z. , Srivastava Ashok K.
Published: May 2007

Transactivation of epidermal growth factor receptor (EGFR) is a well-documented mechanism by which vasoactive peptides and H2O2elicit their cellular responses. However, a role for the insulin-like growth factor type-1 receptor (IGF-1R) transactivation in mediating the effects of angiotensin II (Ang II) and H2O2in vascular smooth muscle cells from different artery types have also been recently recognized. By using a series of pharmacological inhibitors of various growth factor receptor tyrosine kinases and a direct analysis of the phosphorylation status of the β-subunit of IGF-1R, a requirement of this growth factor receptor in Ang II and H2O2response has been demonstrated. This review discusses some of the studies that highlight the importance of IGF-1R transactivation in mediating Ang II- and H2O2-induced mitogen-activated protein kinase and protein kinase B signaling pathways.
The regulation of smooth muscle contractility by zipper-interacting protein kinaseThis paper is one of a selection of papers published in this Special Issue, entitled Young Investigators' Forum.
Authors: Ihara Eikichi , MacDonald Justin A.
Published: May 2007

Smooth muscle contractility is mainly regulated by phosphorylation of the 20 kDa myosin light chains (LC20), a process that is controlled by the opposing activities of myosin light chain kinase (MLCK) and myosin light chain phosphatase (MLCP). Recently, intensive research has revealed that various protein kinase networks including Rho-kinase, integrin-linked kinase, zipper-interacting protein kinase (ZIPK), and protein kinase C (PKC) are involved in the regulation of LC20phosphorylation and have important roles in modulating smooth muscle contractile responses to Ca2+(i.e., Ca2+sensitization and Ca2+desensitization). Here, we review the general background and structure of ZIPK and summarize our current understanding of its involvement in a number of cell processes including cell death (apoptosis), cell motility, and smooth muscle contraction. ZIPK has been found to induce the diphosphorylation of LC20at Ser-19 and Thr-18 in a Ca2+-independent manner and to regulate MLCP activity directly through its phosphorylation of the myosin-targeting subunit of MLCP or indirectly through its phosphorylation of the PKC-potentiated inhibitory protein of MLCP. Future investigations of ZIPK function in smooth muscle will undoubtably focus on determining the mechanisms that regulate its cellular activity, including the identification of upstream signaling pathways, the characterization of autoinhibitory domains and regulatory phosphorylation sites, and the development of specific inhibitor compounds.
Donor cell transplantation for myocardial disease: does it complement current pharmacological therapies?This paper is one of a selection of papers published in this Special Issue, entitled Young Investigators' Forum.
Authors: McMullen Nichole M. , Pasumarthi Kishore B.S.
Published: May 2007

Heart failure secondary to ischemic heart disease, hypertension, and myocardial infarction is a common cause of death in developed countries. Although pharmacological therapies are very effective, poor prognosis and shorter life expectancy of heart disease patients clearly indicate the need for alternative interventions to complement the present therapies. Since the progression of heart disease is associated with the loss of myocardial cells, the concept of donor cell transplantation into host myocardium is emerging as an attractive strategy to repopulate the damaged tissue. To this end, a number of donor cell types have been tested for their ability to increase the systolic function of diseased hearts in both experimental and clinical settings. Although initial clinical trials with bone marrow stem cells are encouraging, long-term consequences of such interventions are yet to be rigorously examined. While additional laboratory studies are required to address several issues in this field, there is also a clear need for further characterization of drug interactions with donor cells in these interventions. Here, we provide a brief summary of current pharmacological and cell-based therapies for heart disease. Further, we discuss the potential of various donor cell types in myocardial repair, mechanisms underlying functional improvement in cell-based therapies, as well as potential interactions between pharmacological and cell-based therapies.
Comparative capacities of the pig colon and duodenum for luminal iron absorption
Authors: Blachier François , Vaugelade Pierre , Robert Véronique , Kibangou Bertille , Canonne-Hergaux François , Delpal Serge , Bureau François , Blottière Hervé , Bouglé Dominique
Published: May 2007

Iron deficiency is the most common human nutritional disorder in the world. Iron absorptive capacity of the small intestine is known to be much limited and therefore large quantities of iron salts must be used to treat iron deficiency. As a result, significant amounts of iron may reach the large intestine. This study compared the capacities of the small and large intestine to transfer luminal iron to the venous blood in relationship with the expression in epithelial cells of proteins involved in iron absorption using a pig model. Intracaecal injection of iron sulphate corresponding with 2.5 and 5.0 mg elemental iron per kg body mass resulted in modest, transient, but significant (p < 0.05) increases in iron concentration in the portal blood plasma. By comparing portal blood plasma iron concentrations following injection in the duodenal and caecal lumen, we calculated that 5 h after injection, iron colonic absorption represented approximately 14% of duodenal absorption. Caecal and proximal colon mucosa accumulated iron to a much lower extent than the duodenal mucosa. Isolated colonocytes were found to express divalent metal transporter (DMT1) and ferritin, but to a lesser extent than the duodenal enterocytes. Ferroportin was highly expressed in colonocytes. In these cells as well as in enterocytes ferroportin was found to be glycosylated. In short term experiments and at a concentration in the range of that measured in the aqueous phases recovered from the large intestine luminal content after iron injection, iron sulphate did not alter colonocyte viability. We concluded that the colonic epithelial cells that express proteins involved in iron absorption are able to transfer luminal iron to the venous blood even if its relative participation in the overall intestinal absorption appears to be modest under our experimental conditions.
Botulinum toxin type A inhibits rat pyloric myoelectrical activity and substance P release in vivo
Authors: Hou Yi-Ping , Zhang Yong-Ping , Song Yan-Feng , Zhu Chun-Min , Wang Yin-Chun , Xie Gui-Lin
Published: May 2007

The effect of botulinum toxin type A (BTX-A) on rat pyloric myoelectrical activity in vivo and the content and distribution of substance P (SP) in pylorus were investigated, respectively, with electromyography, radioimmunoassay, and immunohistochemistry. A pair of electrodes for recording pyloric myoelectrical activity and a guide cannula for drug injection were implanted into the pylorus. The changes of pyloric myoelectrical activity were recorded followed vehicle, 10, 20, and 40 U/kg body mass of BTX-A injection. Pyloric tissues were dissected for radioimmunoassay and immunohistochemistry after recording. The 3 dosages of BTX-A injections caused the reduction of slow wave of pyloric myoelectrical activity in amplitude but not in frequency and the diminishment of spike activity in amplitude and spike burst. The inhibitory effect of 20 U/kg BTX-A was significantly different from that of 10 U/kg (p < 0.05), but not from the effect of 40 U/kg administration (p > 0.05). After BTX-A intrasphincteric injection, SP content was reduced in the pylorus, and cell number of SP-immunoreactivity was decreased more in myenteric nerve plexus of circular muscle and in mucosa of pylori. In conclusion, BTX-A inhibits pyloric myoelectrical slow activity in amplitude and spike activity and weakens pyloric smooth muscle contractility depending on threshold of dose or concentration. BTX-A-induced inhibition of pyloric myoelectrical activity implies a mechanism of inhibiting SP release from the autonomic and enteric nervous terminals in the pylorus.
Feeding by Philoponella vicina (Araneae, Uloboridae) and how uloborid spiders lost their venom glands
Authors: Weng J.-L. , Barrantes G. , Eberhard W.G.
Published: May 2007

Feeding by uloborid spiders is unusual in several respects: cheliceral venom glands are absent; prey wrapping is extensive (up to several hundred metres of silk line) and severely compresses the prey; the spider’s mouthparts usually never touch the prey; and the entire surface of the prey is covered with digestive fluid. This paper presents observations on Philoponella vicina O. Pickard-Cambridge, 1899, which provide possible causal links between these traits. The spider begins ingesting soon after it wets the prey, gaining access to the prey’s interior through a broken cuticle that was broken during wrapping and by digestion of the prey’s membranes. The more abundant of the two types of wrapping lines is also digested, but the remaining shroud of wrapping silk is dense and filters digested prey particles. Robust setae on the palpal tarsus and the spread position of the anterior legs during feeding probably protect the spider from contact with the digestive fluid. Spiders extracted about 65% of the wet contents of the prey, but feeding was slow and involved substantial water evaporation. We propose that selection in uloborid ancestors to recover wrapping silk led to increased wetting of the prey’s surface and that compressive wrapping facilitated this wetting. These traits could have led to loss of the now superfluous cheliceral poison glands.
The role of variability and uncertainty in testing hypotheses involving parameters in stochastic demographic models
Authors: Fieberg J. , Staples D.F.
Published: May 2007

Hierarchical / random effect models provide a statistical framework for estimating variance parameters that describe temporal and spatial variability of vital rates in population dynamic models. In practice, estimates of variance parameters (e.g., process error) from these models are often confused with estimates of uncertainty about model parameter estimates (e.g., standard errors). These two sources of “error” have different implications for predictions from stochastic models. Estimates of process error (or variability) are useful for describing the magnitude of variation in vital rates over time and are a feature of the modeled process itself, whereas estimates of parameter standard errors (or uncertainty) are necessary for interpreting how well we are able to estimate model parameters and whether they differ among groups. The goal of this comment is to illustrate these concepts in the context of a recent paper by A.W. Reed and N.A. Slade (Can. J. Zool. 84: 635–642 (2006)) . In particular, we will show that their “hypothesis tests” involving mean parameters are actually comparisons of the estimated distributions of vital rates among groups of individuals.
Segregation of Beaufort Sea beluga whales during the open-water season
Authors: Loseto L.L. , Richard P. , Stern G.A. , Orr J. , Ferguson S.H.
Published: May 2007

Population segregation by habitat use occurs because energy requirements and survival strategies vary with age, sex, size, and reproductive stage. From late summer to early fall in 1993, 1995, and 1997, relative length (age), sex, and reproductive status of satellite-tagged beluga whales ( Delphinapterus leucas (Pallas, 1776)) in the eastern Beaufort Sea were tested for habitat segregation. We used (i) resource selection function models to evaluate how belugas used areas of varying sea ice concentration and shelf habitat and (ii) distance analysis to measure the selection of areas varying in distance to mainland and island coastlines. Resource selection functions and distance analysis established that habitat selection differed with length, sex, and reproductive status of whales: (i) females with calves and smaller males selected open-water habitats near the mainland; (ii) large males selected closed sea ice cover in and near the Arctic Archipelago; and (iii) smaller males and two females with calves (not newborn) selected habitat near the ice edge. The segregation of habitat use according to sex, age, and reproductive status relates to the different resources required at different life stages and may represent characteristics of beluga social structure. We discuss our results in the context of two common sexual segregation hypotheses and conclude that summer habitat segregation of belugas reflects differences in foraging ecology, risk of predation, and reproduction.
Using effects of parasitoid size on fitness to test a host quality model assumption with the parasitoid wasp Spalangia endius
Authors: King B.H. , Napoleon M.E.
Published: May 2007

How body size affects fitness of males relative to females is relevant to understanding the evolution of sexual size dimorphism and maternal sex-ratio manipulation. In most parasitoid wasps, mothers oviposit a greater proportion of daughters in larger hosts. The host-quality model describes how this may be adaptive. A major assumption of the model is that host size has a greater effect on the fitness of daughters than of sons. The assumption has often been tested indirectly by examining the effects of parasitoid size on fitness, because a parasitoid’s size generally increases with the size of the host on which it develops. The validity of this indirect method is examined here for the parasitoid wasp Spalangia endius Walker, 1839 parasitizing Musca domestica L., 1758. If the method is valid, effects of parasitoid size on fitness should match the effects of host size on fitness that were shown in a previous study. The effects matched in that both parasitoid size and host size affected the fitness of females but not of males. However, the aspects of female fitness that were affected differed. That female size but not male size affected fitness was consistent with the female-biased sexual size dimorphism of S. endius.
Within-clutch egg-size variation in a subsocial bug: the positional effect hypothesis
Authors: Kudo Shin-ichi
Published: May 2007

If there are differences in predation risk among the offspring within a clutch, parents should allocate less resources to the offspring facing higher risk. Predation risk, and thus offspring size, may depend on the spatial position of individual offspring within a clutch. To test this positional effect hypothesis, I examined egg-size (egg-mass) variation in the subsocial bug Elasmucha signoreti Scott, 1874 (Hemiptera: Acanthosomatidae). In subsocial insects, including Elasmucha , in which females guard their clutches against predators by covering the clutch with their bodies, there are large differences in survival between offspring at the centre and at the periphery of the clutch. There was considerable variation in reproductive output among females; female body size was positively correlated with egg mass but not with clutch size. Females laid significantly lighter eggs in the peripheral, and thus more vulnerable, part of the clutch. No phenotypic trade-off between egg mass and clutch size was detected. Egg mass was positively correlated with hatched first-instar nymph mass. Thus, E. signoreti females seem to allocate their resources according to the different predation risks faced by the offspring within a clutch. I suggest that the positional effect hypothesis can generally be applicable to species whose females lay eggs in clutches and that the eggs suffer different mortality rates which depend on their spatial positions within the clutch.
At-sea movements and habitat use of adult male Australian fur seals (Arctocephalus pusillus doriferus)
Authors: Kirkwood Roger , Lynch Michael , Gales Nick , Dann Peter , Sumner Michael
Published: May 2007

Foraging by adult male otariids, a demographic component that often interacts with commercial fisheries, are poorly known. To assess movement patterns and habitat use, nine adult male Australian fur seals ( Arctocephalus pusillus doriferus Wood Jones, 1925) from Seal Rocks, in northern Bass Strait, southeastern Australia, were tracked for periods ranging from 66 to 223 d during 1999–2001. Mean ± SD at-sea and on-land durations were 6.9 ± 2.1 d (range 2.3–10.3 d, n = 9 seals) and 2.4 ± 0.9 d (range 0.8–4.1 d), respectively. All seals foraged almost exclusively in continental shelf waters and mostly (65%–97% of time at sea) in water columns that were between 40 and 100 m deep. Six of nine seals tracked for >30 d spent 64%–98% of their time-at-sea foraging at distances <200 km from Seal Rocks, although the maximum distance achieved from the colony was 1208 km. The seals’ foraging ranges overlapped with the ranges of operation of virtually all fin-fish fisheries in southeastern Australia, but fisheries overlap was low in the most frequented foraging area of central-western Bass Strait.
Demographic independence along ecosystem boundaries in Steller sea lions revealed by mtDNA analysis: implications for management of an endangered species
Authors: O’Corry-Crowe G. , Taylor B.L. , Gelatt T. , Loughlin T.R. , Bickham J. , Basterretche M. , Pitcher K.W. , DeMaster D.P.
Published: May 2007

Previous genetic studies indicate Steller sea lions ( Eumetopias jubatus (Schreber, 1776)) comprise three phylogeographically distinct populations. However, differences in population trends and ecology and the limited extent of recorded dispersal suggest structure may be present at smaller scales. We examined sequence variation within a longer segment (531 bp) of the mtDNA control region in greater numbers (n = 1654) of sea lions from across Alaska than earlier investigations to investigate fine-scale dispersal patterns in Steller sea lions. We detected high levels of haplotypic diversity (h = 0.934) and confirmed phylogeographic differentiation between southeastern and western Alaska (Φst= 0.23, P < 0.0001), but also found significant differentiation at regional and local scales. Rookeries in the Gulf of Alaska, eastern Bering Sea, and eastern Aleutians were distinct from rookeries in the central and western Aleutians (Fst= 0.021, P < 0.0001; Φst= 0.017, P < 0.0001). The location of this split coincides with an oceanographic divergence between continental shelf and ocean basin waters and with differences in sea lion foraging ecology and population trends. A number of rookeries were also significantly differentiated from nearby rookeries (Fst= 0.02–0.025, P < 0.05), signifying substantial female-mediated philopatry, in some cases, at local scales. These findings have important implications for understanding the ecology of Steller sea lions in relation to marine ecosystems and the causes of population declines, and they provide guidance for management, including the identification of management stocks.
Simulated winter browsing may lead to induced susceptibility of willows to beavers in spring
Authors: Veraart Annelies J. , Nolet Bart A. , Rosell Frank , de Vries Peter P.
Published: May 2007

Browsing may lead to an induced resistance or susceptibility of the plant to the herbivore. We tested the effect of winter browsing by Eurasian beavers ( Castor fiber L., 1758) on food quality of holme willows ( Salix dasyclados Wimm.) in and after the following growth season. Shrubs were pruned in February, and new shoots from these (cut) shrubs were compared with those of untreated (uncut) ones in May and November. The shoots were analysed for dry matter, nitrogen, acid detergent fibre, and total phenolics. In May, the leaves from the cut treatment had a better food quality (more water, more nitrogen, and less phenolics) than those from the uncut one. There was in part also a systemic response, with lower total phenolics in both the cut and untreated parts of pruned shrubs (uncut–cut) than in the uncut shrubs. In November, we did not find significant differences in biochemistry of bark among cut, uncut, or uncut–cut treatments. These results are in accordance with a cafeteria experiment in the field: in May the beavers preferred shoots from the cut treatment, but in November they showed no preference. The results suggest that willows invest in compensatory growth rather than a defence response early in the regrowing phase.
Comparative demography of a temperate anuran, Rana chensinensis, along a relatively fine elevational gradient
Authors: Lu Xin , Li Bin , Liang Juan Juan
Published: May 2007

Rana chensinensis (David, 1875) is a temperate anuran endemic to northern China. We examined differences in demographic traits of the populations from three elevations (1400, 1700, and 2000 m) along a montane river in 2002. We found that frogs from higher elevations had delayed maturity, a larger size at maturity, and slower growth rates compared with frogs at lower elevations. This life-history model is similar to observations of other amphibians living in montane areas. However, discordance with the expected model occurred between neighboring populations and the variation was sex-specific. Mid-elevation adult males were significantly older and larger than their low-elevation congeners, but they were statistically similar in age and size to frogs from high elevations; females from mid elevations were not statistically different in age and size from females from our low-elevation site, but they were significantly younger and smaller than high-elevation females. These variations may be related to sexual differences in life-history strategies, which might not covary systematically when elevational gradients are set at a finer scale. At each elevation, the sex ratio was skewed towards females; females also matured later, lived longer, and were larger. Age was a major factor related to size, but other factors played a role in shaping size differences both between populations and between sexes.
Effect of lipid extraction on analyses of stable carbon and stable nitrogen isotopes in coastal organisms of the Aleutian archipelago
Authors: Ricca M.A. , Miles A.K. , Anthony R.G. , Deng X. , Hung S.S.O.
Published: May 2007

We tested whether extracting lipids reduced confounding variation in δ13C and δ15N values by analyzing paired lipid-extracted (LE) and non-lipid-extracted (NLE) samples of bald eagle ( Haliaeetus leucocephalus (L., 1766)) whole eggs, muscle tissue from nine seabird and one terrestrial bird species, muscle tissue from four marine fish species, and blue mussels ( Mytilus edulis L., 1758) collected from the Aleutian archipelago, Alaska. Lipid extraction significantly increased δ13C by an average of 2.0‰ in whole eggs, 0.8‰ in avian muscle, 0.2‰ in fish muscle, and 0.6‰ in blue mussels. Lower δ13C values in NLE samples covaried positively with lipid content across all sample types. Lower δ13C values in NLE samples were not correlated with lipid content within bald eagle eggs and blue mussels, but covaried positively with percent lipid in avian and fish muscles. Neither lipid extraction nor percent lipid significantly changed δ15N values for any sample type. Lower δ13C values in most NLE avian and fish muscle tissues should not confound interpretation of pelagic versus nearshore sources of primary production, but lipid extraction may be necessary when highly precise estimates of δ13C are needed. Lipid extraction may not be necessary when only δ15N is of interest.
Growth and reproduction of female short-beaked common dolphins,Delphinus delphis, in the eastern tropical Pacific
Authors: Danil K. , Chivers S.J.
Published: May 2007

We characterize the life-history strategy of female short-beaked common dolphins ( Delphinus delphis L., 1758) inhabiting the eastern tropical Pacific by estimating several growth and reproductive parameters. Reproductive condition (n = 700) and age (n = 405) were determined for animals sampled from those incidentally killed in the yellowfin tuna ( Thunnus albacares (Bonnaterre, 1788)) purse-seine fishery between 1975 and 1993. Females averaged 160.4 cm at age 2 years, 186.5 cm at attainment of sexual maturity, and 197.2 cm at asymptotic length. The estimated age at attainment of sexual maturity was 7.9 years and the oldest animal in the study was 25 years. Calving occurred throughout the year, with females producing a calf approximately every 2.1 years after a gestation period of approximately 11.4 months, an average lactation period of 16.5 months, and an average resting period of 2.8 months. A relatively high percentage (30.4%) of lactating females were simultaneously pregnant, which effectively shortens the average calving interval. No clear evidence of senescence was found. Estimated lengths at birth, 2 years of age, attainment of sexual maturity, and maximum size were greater than those reported for the temperate North Pacific population, indicating that large-scale geographic variation in life history occurs for this species, which likely reflects population-specific adaptations to the tropical and temperate habitats that they occupy.
Settlement patterns, foraging behavior, and reproductive success of ospreys along a heterogeneous riverine corridor
Authors: Harmata Peter J. , Restani Marco , Harmata Alan R.
Published: May 2007

In 1998 and 1999, we determined the spatial distribution, foraging behavior, and reproductive success of ospreys ( Pandion haliaetus (L., 1758)) nesting along the upper Missouri River, Montana. We combined our data with that collected in the same area in 1981–1982 and 1990–1991 to investigate factors influencing settlement patterns. The study area was composed of four distinct habitats, three reservoirs and one free-flowing river section. Although number of occupied nests on each habitat increased from 1981–1982 to 1998–1999, the greatest percentage increases in nest density occurred on habitats previously hypothesized to contain the least prey. Osprey reproductive success was positively related to foraging rates, which differed across habitats, being highest on reservoirs and lowest on the free-flowing river. However, reproductive success was adequate for replacement on each habitat. Most fish consumed by ospreys on each habitat were suckers (Catostomidae), followed by salmonids and cyprinids. Fish density, determined from gill netting, was highest on the largest and shallowest reservoir. Over two decades, ospreys shifted their relative spatial use of the upper Missouri River such that reservoirs were occupied first and the free-flowing river section was occupied last. The degree to which presence of conspecifics, distribution of nest trees and prey, and dispersal affected settlement patterns probably varied by spatial scale.
Bone microstructure: quantifying bone vascular orientation
Authors: de Boef M. , Larsson H.C.E.
Published: May 2007

Bone microstructure often preserves a temporal record of the life history of the animal to which it belongs. Previously used bone microstructure metrics to differentiate between primary bone types are reviewed and tested with a broad sample of bone types. Two new metrics, the radial index and the longitudinal index, are developed to quantitatively differentiate bone types based on bone vascular orientation in three dimensions. All previously used metrics described the bone microstructure in a nonlinear pattern and were unable to separate bone types satisfactorily. The radial index and longitudinal index effectively differentiated bone types and described bone microstructure within a linear continuum. The continuous nature of the range of vascular orientation in bone microstructure necessitates a quantitative approach rather than the commonly used qualitative classifications. The radial index and longitudinal index, which objectively detect small differences in vascular orientation in three dimensions, are therefore preferable to other metrics for inter- and intra-specific comparisons of bone microstructure. These metrics offer novel methods to facilitate examinations of the relationship between primary bone type and ontogeny, biomechanics, and phylogeny.
Ecological correlates of the distribution of territorial Svalbard rock ptarmigan (Lagopus muta hyperborea)
Authors: Pedersen Å.Ø. , Jepsen J.U. , Yoccoz N.G. , Fuglei E.
Published: May 2007

Predictive habitat models have become important research and management tools for monitoring the spatial distribution and abundance of wildlife species. In this paper we develop and evaluate statistical habitat models for presence of territorial Svalbard rock ptarmigan ( Lagopus muta hyperborea Sundevall, 1845) cocks in spring and apply the best model to assess ptarmigan habitat selection in a larger extrapolated region. Terrain variables were extracted at detailed (10 m digital elevation model (DEM)) and coarse (50 m DEM) scales to compare model performance. Sets of candidate environmental variables related to terrain and vegetation cover were developed and explanatory variables were calculated at increasing distances from the count site to well above the typical size of ptarmigan territory. We used ecological niche factor analysis to describe the difference between used and available sites. Survey sites used by cocks were characterized by a restricted range of altitude, a high degree of terrain heterogeneity, and dense vegetation cover compared with overall site availability in the survey region. We then used model selection criteria (AICc) to find the most parsimonious logistic regression models estimating habitat resource selection functions for cocks. Detailed terrain variables were better predictors than coarse terrain variables. The normalized difference vegetation index (NDVI) was a good predictor of presence of territorial cocks, but not as good as the most preferred habitat type. Owing to limited availability of high-quality vegetation maps, the best model containing NDVI and 10 m DEM variables was used for extrapolation of male ptarmigan habitat. Our results show that it is possible to obtain a model with a high ability to rank habitats using a low number of map-derived variables. Such rankings can then be used to improve field sampling designs and are therefore a useful tool for management and conservation of ptarmigan and wildlife in Arctic and alpine areas.