bluuebunny/crossref_metadata_2025 huggingface dataset:
On the behavioural response ofRanaandBufotadpoles to echinostomatoid cercariae: implications to synergistic factors influencing trematode infections in anurans
Authors: Taylor Christopher N , Oseen Kerri L , Wassersug Richard J
Published: August 2004

We used high-speed videography of staged encounters between tadpoles of either Bufo americanus Holbrook, 1836 or Rana sylvatica LeConte, 1825 and Echinostoma Rudolphi, 1809 cercariae to understand why echinostomatoid trematodes, such as species from the genera Echinostoma and Ribeiroia Travassos, 1939 (implicated in anuran limb deformities), attack specific anatomical regions of tadpoles. Bufo and Rana tadpoles can shed cercariae on their skin from some parts of their body more easily than others. In particular, cercariae that enter the "dead-water zone" at the junction of a tadpole's body and tail appear particularly difficult for tadpoles to brush off. Cercariae that reach this recess can easily enter the inguinal region of tadpoles (as do Ribeiroia spp.) or ascend the tadpole's cloaca (as do Echinostoma spp.). When tadpoles sense cercariae contacting their skin they make explosive movements to shed those parasites. Factors that reduce tadpoles' activity, such as predator threat or certain pesticides, may increase a tadpole's susceptibility to echinostomatoid infection. Because Bufo tadpoles are unpalatable to many predators, they can afford to make more conspicuous evasive maneuvers than Rana tadpoles, and do so in the laboratory. Bufo tadpoles in the field also have a lower rate and different anatomical distribution pattern of Ribeiroia infection than Rana tadpoles. Factors that reduce tadpole activity in the field may act synergistically to increase parasite loads and subsequent deformities in anurans.
Effect of altitudinal migration within a watershed on the reproductive success of American dippers
Authors: Morrissey Christy A
Published: August 2004

Distinct changes occur in the distribution of American dipper (Cinclus mexicanus Swainson, 1827) populations during the breeding season. Small numbers of American dippers remain resident on the wintering site, while the majority of birds make short altitudinal movements upstream. Therefore, American dippers breed over large elevation gradients within a watershed, using both the main river and its associated tributaries. I hypothesized that altitudinal migration of American dippers would affect their timing of breeding and ultimately their productivity. Additionally, since the main river and its tributaries differ in habitat, elevation, and nesting substrates, I hypothesized that these variables would also influence American dipper breeding performance. In the Chilliwack watershed of British Columbia, Canada, I followed 99 pairs of American dippers: 23 in 1999, 40 in 2000, and 36 in 2001, of which approximately 65% were residents and 35% were migrants. Resident pairs on the lower elevation river initiated nests earlier and a greater proportion had second broods, contributing to slightly higher nest success and annual productivity compared with migrants on tributaries. Reduced productivity was primarily associated with later onset of breeding, which increased the likelihood that nests were lost to predation or flooding and reduced the probability of initiating a second clutch. Timing of breeding was affected by migratory status and year, but elevation and habitat did not directly influence breeding performance.
Recruitment, population structure, and habitat selection of Corynosoma australe (Acanthocephala) in South American fur seals, Arctocephalus australis, from Uruguay
Authors: Aznar F J , Cappozzo H L , Taddeo D , Montero F E , Raga J A
Published: August 2004

We analysed recruitment, population structure, and intestinal distribution of Corynosoma australe Johnston, 1937 in 27 South American fur seals, Arctocephalus australis (Zimmerman, 1783), collected in two Uruguayan localities during 1990 and 1991. Only heavy infections of C. australe were found in all intestines. High transmission rates might result from the massive concentration of fur seals in the study area and the ecological ubiquity of C. australe. Intestinal length (IL) accounted, through a cubic relationship, for most of the variation (74%) in parasite intensity. IL3 also predicted the percentage of juvenile females among hosts (an indicator of recruitment rate) better than intensity or host body size. Intestinal size might be a suitable surrogate of host metabolic rate, the potential factor influencing intensity. The percentages of females and gravid females significantly increased along the intestine, and the distribution of juvenile females, gravid females, and males significantly covaried after controlling for intensity effects. These patterns suggest that worms migrate towards the lower jejunum and ileum while they mature, copulate, and reproduce. Males and gravid females shifted their distribution anteriad, and gravid females expanded their distribution, with intensity. These patterns might result from recruitment dynamics, intraspecific competition, or both. We do not know why males, gravid females, and juvenile females respond differently to these factors.
Note types and coding in parid vocalizations. II: The chick-a-dee call of the mountain chickadee (Poecile gambeli)
Authors: Bloomfield Laurie L , Charrier Isabelle , Sturdy Christopher B
Published: August 2004

We describe the chick-a-dee call of the mountain chickadee, Poecile gambeli (Ridgway, 1886), by classifying the various call notes into six types (A, A/B, B, C, Dh, and D). Note-type analyses identify a high degree of similarity among A and A/B notes in the ascending duration, descending duration, and note peak frequency, and among A/B and B notes in the end frequency. This statistical result paralleled disagreements between human sorters where A, A/B, and B notes were most often misclassified. Moreover, virtually all parameters measured showed significant variation across individuals. Therefore, the particular acoustic cues used in the discrimination of note types and individuals remain unknown, but it is likely that a constellation of features is used rather than one or two particularly salient features.
Age, sex, and season affect the risk of mycoplasmal conjunctivitis in a southeastern house finch population
Authors: Altizer Sonia , Davis Andrew K , Cook Katherine C , Cherry John J
Published: August 2004

House finches (Carpodacus mexicanus (Muller, 1776)) in eastern North America have been affected by annual epidemics of an eye disease caused by the bacterium Mycoplasma gallisepticum since 1994. To identify factors associated with seasonal changes in prevalence and variation in host susceptibility, we monitored mycoplasmal conjunctivitis among wild house finches in a region of high prevalence in southeastern North America. We captured 888 birds between August 2001 and December 2003 and observed seasonal outbreaks characterized by rapid increases in prevalence from August to October each year. During periods of high prevalence, infection probability was significantly higher among juveniles than adults, and the severity of conjunctivitis among juvenile females was greater than for any other host category. We found no evidence linking moulting status to elevated infection risk among adult birds. Finally, house finches with conjunctivitis were in poorer condition than birds with no clinical signs of infection, particularly among those with severe infections. Results from this study are consistent with recent reports of seasonal and regional variation in mycoplasmal conjunctivitis and suggest that annual changes in host reproduction, behaviour, and age structure might be important determinants of the timing and magnitude of local epidemics.
An intra- and inter-island study of the polytene chromosomes of Simulium exasperans (Diptera: Simuliidae)
Authors: Spironello Mike , Hunter Fiona F
Published: August 2004

The polytene chromosome banding pattern of Simulium exasperans (Craig, 1987) is described for the first time. Three populations of S. exasperans from Moorea and Tahiti were examined cytologically. Interspecific comparisons revealed that S. exasperans is homosequential in chromosomal banding pattern to Simulium cataractarum (Craig, 1987), but contains three species-characteristic floating inversions: IL-1ex.2ex, IIL-1ex,2ex, and IIIL-1ex. No sex-linked inversions were identified; males and females had undifferentiated sex chromosomes. The IIL-1ex,2ex inversion was in Hardy-Weinberg disequilibrium in two of the three populations. From this preliminary data, two cytotypes may exist: cytotype A (Belvedre Cascade population) and cytotype B (1st Afareaitu Cascade and Jardin Public Vaipahi populations). Contrary to phylogenetic and biogeographic data, it is hypothesized that the Belvedre Cascade population (cytotype A) is ancestral to the populations containing cytotype B. Furthermore, a heterozygote advantage may exist in cytotype B.
Diurnal cycle of Isospora spp. oocyst shedding in Eurasian blackbirds (Turdus merula)
Authors: Misof Katharina
Published: August 2004

Diurnal fluctuations in the appearance of parasites have been recognized for more than 60 years but have been largely ignored in studies examining the role of parasites in connection with evolutionary aspects of behaviour, ecology, and population dynamics. The disregard of diurnal fluctuations, however, can influence the reliability and interpretation of data. I examined shedding of Isospora spp. oocysts in faeces of naturally infected, free-living Eurasian blackbirds (Turdus merula L., 1758). Adult birds and nestlings shed coccidian oocysts (Isospora spp.) predominantly in the afternoon. The results are in agreement with earlier studies on coccidian oocyst shedding in other bird species. They are discussed with regard to these studies and to practical implications for future investigators in this field.
Variation in the reproductive rate of bats
Authors: Barclay Robert M.R , Ulmer Joel , MacKenzie Cameron J.A , Thompson Megan S , Olson Leif , McCool Julianne , Cropley Elvie , Poll Graeme
Published: August 2004

In many respects, bats have relatively slow life histories. However, the reproductive rate of bats (i.e., the proportion of females that reproduce in any breeding season) has not been critically examined. We compiled data on the reproductive rates of bats to test predictions based on life-history theory. Among 257 samples from 103 species, reproductive rate varied considerably and was typically under 100%. Temperate-zone species had significantly lower and more variable reproductive rates than did tropical species. Reproductive rate also varied among families, with species in the Vespertilionidae having particularly high rates. As predicted based on life-history theory, reproductive rate was negatively correlated with longevity, and among vespertilionids, species with larger litters had higher reproductive rates. Thus, the data suggest that bats have relatively slow reproductive rates and, as in other life-history traits, fall at the "slow" end of the fast–slow life-history continuum found among mammals. Female bats, especially those in temperate regions, appear to adjust their allocation of resources to reproduction, and at times forego reproduction, perhaps in relation to their body condition, prey availability, and weather conditions.
Natural hybridization between Dall's porpoises (Phocoenoides dalli) and harbour porpoises (Phocoena phocoena)
Authors: Willis Pamela M , Crespi Bernard J , Dill Lawrence M , Baird Robin W , Hanson M Bradley
Published: August 2004

Natural hybridization occurs rarely in mammals compared with other taxonomic groups of animals. Cetaceans appear unique among mammals in exhibiting striking karyological uniformity, which suggests that they have the potential to produce hybrid offspring more readily than other mammals. However, the detection and accurate identification of wild mammalian hybrids is difficult, and molecular evidence for wild cetacean hybrids is extremely limited. Here, we present molecular and morphological evidence of frequent hybridization between free-ranging Dall's, Phocoenoides dalli (True, 1885), and harbour, Phocoena phocoena (L., 1758), porpoises. The study describes a temporally and geographically concentrated case of natural hybridization in large mammals. Molecular analyses of mitochondrial and nuclear DNA revealed the species identity, sex, and direction of cross of several hybrid individuals. In concert with morphological and behavioural observations, these data confirmed the hybrid status of putative crosses in the field, including reproductive females. All crosses examined had Dall's porpoise as the maternal parent. This directionality may reflect the indiscriminate pursuit of female porpoises by male harbour porpoises. Our finding of extensive localized hybridization, despite apparently strong isolation elsewhere in their range, suggests that ecological influences on mating behaviour may be of primary importance in the reproductive isolation of these, and possibly other, cetacean species.
The effects of temperature on prey-capture kinematics of the bluegill (Lepomis macrochirus): implications for feeding studies
Authors: Wintzer A P , Motta P J
Published: August 2004

Research with ectothermic organisms has demonstrated that temperature is positively correlated with an individual's power output during locomotion. This study investigates the effect of temperature on another aspect of power output, prey-capture kinematics, of the bluegill (Lepomis macrochirus Rafinesque, 1819). Feeding sequences for two treatments of four sunfish were filmed at three temperatures (18, 24, and 30 °C) with one treatment (A) experiencing an increasing range of temperatures and the other (B) experiencing a decreasing temperature range. Directional temperatures affected prey-capture kinematics. The time required to achieve maximum lower jaw depression and maximum gape, as well as the duration of maximum gape, time to close the mouth (from the point of maximum gape), and the total bite duration, increased as water temperature decreased. In addition, both the time to maximum gape and the time to maximum lower jaw depression were longer at 18 °C for individuals in treatment A than those in treatment B. These results indicate that water temperature can bias the results of feeding studies employing kinematics that do not control for its effects as well as those that make comparisons across such studies which utilize different temperatures and taxa.
THE INVARIANT MEASURES AT WEAK DISORDER FOR THE TWO-LINE ANDERSON MODEL
Authors: DORLAS T. C. , PULÉ J. V.
Published: August 2004

We study the invariant measures in the weak disorder limit, for the Anderson model on two coupled chains. These measures live on a three-dimensional projective space, and we use a total set of functions on this space to characterize the measures. We find that at several points of the spectrum, there are anomalies similar to that first found by Kappus and Wegner for the single chain at zero energy.
THE RADIAL PART OF THE ZERO-MODE HAMILTONIAN FOR SIGMA MODELS WITH GROUP TARGET SPACE
Authors: PICKRELL DOUG
Published: August 2004

In this note, we use geometric arguments to derive a possible form for the radial part of the "zero-mode Hamiltonian" for the two-dimensional sigma model with target space S3, or more generally a compact simply connected Lie group.
ENERGY AND MOMENTUM ASSOCIATED WITH A STATIC AXIALLY SYMMETRIC VACUUM SPACETIME
Authors: GAD RAGAB M.
Published: August 2004

We use the Einstein and Papapetrou energy–momentum complexes to calculate the energy and momentum densities of the Weyl metric. Further, using these results we obtain the energy and momentum density components for the Curzon metric (a particular case of the Weyl metric). We find that these two definitions of energy–momentum complexes do not provide the same energy density for Weyl metric, although they give the same momentum density. We show that, in the case of Curzon metric, these two definitions give the same energy only when R→∞. Furthermore, we compare these results with those obtained using Landau and Lifshitz, Bergmann and Møller prescriptions.
THE BOSONIC SIGMA MODEL ON A TOROIDAL SURFACE
Authors: McKEON D. G. C.
Published: August 2004

The nonlinear sigma model with a two-dimensional basis space and an n-dimensional target space is considered. Two different basis spaces are considered; the first is an 0(2)×0(2) subspace of the 0(2,2) projective space related to the Minkowski basis space, and the other is a toroidal space embedded into three-dimensional Euclidean space, characterized by radii R and r. The target space is taken to be an arbitrarily curved Riemannian manifold. One-loop dependence on the renormalization induced scale μ is shown in the toroidal basis space to be the same as in a flat or spherical basis space.
Endurance training increases LKB1 and MO25 protein but not AMP-activated protein kinase kinase activity in skeletal muscle
Authors: Taylor E. B. , Hurst D. , Greenwood L. J. , Lamb J. D. , Cline T. D. , Sudweeks S. N. , Winder W. W.
Published: August 2004

LKB1 complexed with MO25 and STRAD has been identified as an AMP-activated protein kinase kinase (AMPKK). We measured relative LKB1 protein abundance and AMPKK activity in liver (LV), heart (HT), soleus (SO), red quadriceps (RQ), and white quadriceps (WQ) from sedentary and endurance-trained rats. We examined trained RQ for altered levels of MO25 protein and LKB1, STRAD, and MO25 mRNA. LKB1 protein levels normalized to HT (1 ± 0.03) were LV (0.50 ± 0.03), SO (0.28 ± 0.02), RQ (0.32 ± 0.01), and WQ (0.12 ± 0.03). AMPKK activities in nanomoles per gram per minute were HT (79 ± 6), LV (220 ± 9), SO (22 ± 2), RQ (29 ± 2), and WQ (42 ± 4). Training increased LKB1 protein in SO, RQ, and WQ ( P < 0.05). LKB1 protein levels after training (%controls) were SO (158 ± 17), RQ (316 ± 17), WQ (191 ± 27), HT (106 ± 2), and LV (104 ± 7). MO25 protein after training (%controls) was 595 ± 71. Training did not affect AMPKK activity. MO25 but not LKB1 or STRAD mRNA increased with training ( P < 0.05). Trained values (%controls) were MO25 (164 ± 22), LKB1 (120 ± 16), and STRAD (112 ± 17). LKB1 protein content strongly correlated ( r = 0.93) with citrate synthase activity in skeletal muscle ( P < 0.05). In conclusion, endurance training markedly increased skeletal muscle LKB1 and MO25 protein without increasing AMPKK activity. LKB1 may be playing multiple roles in skeletal muscle adaptation to endurance training.
Evidence for mitochondrial thioesterase 1 as a peroxisome proliferator-activated receptor-α-regulated gene in cardiac and skeletal muscle
Authors: Stavinoha Melissa A. , RaySpellicy Joseph W. , Essop M. Faadiel , Graveleau Christophe , Abel E. Dale , Hart-Sailors Mary L. , Mersmann Harry J. , Bray Molly S. , Young Martin E.
Published: August 2004

The physiological role of mitochondrial thioesterase 1 (MTE1) is unknown. It was proposed that MTE1 promotes fatty acid (FA) oxidation (FAO) by acting in concert with uncoupling protein (UCP)3. We previously showed that ucp3 is a peroxisome proliferator-activated receptor-α (PPARα)-regulated gene, allowing induction when FA availability increases. On the assumption that UCP3 and MTE1 act in partnership to increase FAO, we hypothesized that mte1 is also a PPARα-regulated gene in cardiac and skeletal muscle. Using real-time RT-PCR, we characterized mte1 gene expression in rat heart and soleus muscles. Messenger RNA encoding for mte1 was 3.2-fold higher in heart than in soleus muscle. Cardiac mte1 mRNA exhibited modest diurnal variation, with 1.4-fold higher levels during dark phase. In contrast, skeletal muscle mte1 mRNA remained relatively constant over the course of the day. High-fat feeding, fasting, and streptozotocin-induced diabetes, interventions that increase FA availability, muscle PPARα activity, and muscle FAO rates, increased mte1 mRNA in heart and soleus muscle. Conversely, pressure overload and hypoxia, interventions that decrease cardiac PPARα activity and FAO rates, repressed cardiac mte1 expression. Specific activation of PPARα in vivo through WY-14643 administration rapidly induced mte1 mRNA in cardiac and skeletal muscle. WY-14643 also induced mte1 mRNA in isolated adult rat cardiomyocytes dose dependently. Expression of mte1 was markedly lower in hearts and soleus muscles isolated from PPARα-null mice. Alterations in cardiac and skeletal muscle ucp3 expression mirrored that of mte1 in all models investigated. In conclusion, mte1, like ucp3, is a PPARα-regulated gene in cardiac and skeletal muscle.
Attenuation of vasopressin-induced antidiuresis in poorly controlled type 2 diabetes
Authors: Agha Amar , Smith Diarmuid , Finucane Francis , Sherlock Mark , Morris Andrew , Baylis Peter , Thompson Christopher J.
Published: August 2004

Renal resistance to vasopressin has been demonstrated in type 1 diabetes and in type 2 diabetes with nephropathy. However, renal response to vasopressin in type 2 diabetes without nephropathy has not been studied. We studied 10 subjects with poorly controlled type 2 diabetes (PCDS; Hb A1c >9%), 10 subjects with well-controlled type 2 diabetes (WCDS; Hb A1c <7%), and 10 matched nondiabetic control subjects (NDCS) during a euglycemic 8-h water deprivation test. None of the subjects had nephropathy. Water deprivation caused similar rises in plasma vasopressin concentrations in all three groups, but the rise in urine osmolality in PCDS (280.3 ± 49.7 to 594.4 ± 88.5 mosmol/kgH2O) was lower than in WCDS (360.7 ± 142.8 to 794.1 ± 77.3 mosmol/kgH2O, P < 0.001) or NDCS (336.0 ± 123.3 to 786.5 ± 63.3 mosmol/kgH2O, P = 0.019). Total urine output was higher in the PCDS than in WCDS and NDCS ( P < 0.05). Linear regression analysis showed that, in PCDS, the osmotic thresholds for thirst (291.9 ± 4.6 mosmol/kgH2O) and vasopressin release (291.1 ± 2.9 mosmol/kgH2O) were higher compared with WCDS (286.6 ± 1.8 and 286.0 ± 3.6 mosmol/kgH2O, respectively) and NDCS (286.0 ± 2.4 and 284.1 ± 4.7 mosmol/kgH2O, respectively) (between groups P < 0.001 for both variables). Under conditions of euglycemia, PCDS have impaired renal response to vasopressin and elevated osmotic threshold for thirst and vasopressin release in response to dehydration. Under conditions of chronic hyperglycemia, these abnormalities may significantly contribute to the development of dehydration in PCDS.
Short-term intermittent exposure to diazoxide improves functional performance of β-cells in a high-glucose environment
Authors: Yoshikawa Hiroyasu , Ma Zuheng , Björklund Anneli , Grill Valdemar
Published: August 2004

Prolonged periods of “β-cell rest” exert beneficial effects on insulin secretion from pancreatic islets subjected to a high-glucose environment. Here, we tested for effects of short-term intermittent rest achieved by diazoxide. Rat islets were cultured for 48 h with 27 mmol/l glucose alone, with diazoxide present for 2 h every 12 h or with continuous 48-h presence of diazoxide. Both protocols with diazoxide enhanced the postculture insulin response to 27 mmol/l glucose, to 200 μmol/l tolbutamide, and to 20 mmol/l KCl. Intermittent diazoxide did not affect islet insulin content and enhanced only KATP-dependent secretion, whereas continuous diazoxide increased islet insulin contents and enhanced both KATP-dependent and -independent secretory effects of glucose. Intermittent and continuous diazoxide alike increased postculture ATP-to-ADP ratios, failed to affect [14C]glucose oxidation, but decreased oxidation of [14C]oleate. Neither of the two protocols affected gene expression of the ion channel-associated proteins Kir6.2, sulfonylurea receptor 1, voltage-dependent calcium channel-α1, or Kv2.1. Continuous, but not intermittent, diazoxide decreased significantly mRNA for uncoupling protein-2. A 2-h exposure to 20 mmol/l KCl or 10 μmol/l cycloheximide abrogated the postculture effects of intermittent, but not of continuous, diazoxide. Intermittent diazoxide decreased islet levels of the SNARE protein SNAP-25, and KCl antagonized this effect. Thus short-term intermittent diazoxide treatment has beneficial functional effects that encompass some but not all characteristics of continuous diazoxide treatment. The results support the soundness of intermittent β-cell rest as a treatment strategy in type 2 diabetes.
Exposure to pressure stimulus enhances succinate dehydrogenase activity in L6 myoblasts
Authors: Morita Noriteru , Iizuka Kenji , Okita Koichi , Oikawa Takashi , Yonezawa Kazuya , Nagai Tatsuya , Tokumitsu Yukiko , Murakami Takeshi , Kitabatake Akira , Kawaguchi Hideaki
Published: August 2004

Contraction of skeletal muscle generates pressure stimuli to intramuscular tissues. However, the effects of pressure stimuli, other than those created by electricity or nerve impulse, on physiological and biochemical responses in skeletal muscles are unknown. The purpose of this study is to examine the effects of a pure pressure stimulus on metabolic responses in a skeletal muscle cell line. Atmospheric pressure was applied to L6 myoblasts using an original apparatus. Succinate dehydrogenase (SDH) activity was evaluated by colorimetric assay using tetrazolium monosodium salt. The amounts of 2-deoxy-[3H]glucose uptake and lactate release were measured. SDH activity was 2.6- to 2.9-fold higher in pressurized L6 cells than in nonpressurized L6 cells ( P < 0.01), and 2-deoxy-[3H]glucose uptake was 2.2-fold higher ( P < 0.001). In addition, the amount of released lactate decreased from 6.8 to 3.7 μmol/dish when pressure was applied ( P < 0.001). In contrast, the intracellular lactate contents of the pressurized cells were higher than those of nonpressurized cells ( P < 0.01). However, the total amount of released lactate and intracellular lactate was lower in the pressurized cells than in nonpressurized cells. These findings demonstrate that a pure pressure stimulus enhances aerobic metabolism in L6 skeletal muscle cells and raise the possibility that elevated intramuscular pressure during muscle activity may be an important factor in stimulating oxidative metabolic responses in skeletal muscles.
Lipoprotein lipase in the kidney: activity varies widely among animal species
Authors: Ruge Toralph , Neuger Lucyna , Sukonina Valentina , Wu Gengshu , Barath Stefan , Gupta Jitendra , Frankel Barbara , Christophersen Bjørn , Nordstoga Knut , Olivecrona Thomas , Olivecrona Gunilla
Published: August 2004

Much evidence points to a relationship among kidney disease, lipoprotein metabolism, and the enzyme lipoprotein lipase (LPL), but there is little information on LPL in the kidney. The range of LPL activity in the kidney in five species differed by >500-fold. The highest activity was in mink, followed by mice, Chinese hamsters, and rats, whereas the activity was low in guinea pigs. In contrast, the ranges for LPL activities in heart and adipose tissue were less than six- and fourfold, respectively. The activity in the kidney (in mice) decreased by >50% on food deprivation for 6 h without corresponding changes in mRNA or mass. This decrease in LPL activity did not occur when transcription was blocked with actinomycin D. Immunostaining for kidney LPL in mice and mink indicated that the enzyme is produced in tubular epithelial cells. To explore the previously suggested possibility that the negatively charged glomerular filter picks up LPL from the blood, bovine LPL was injected into rats and mice. This resulted in decoration of the glomerular capillary network with LPL. This study shows that in some species LPL is produced in the kidney and is subject to nutritional regulation by a posttranscriptional mechanism. In addition, LPL can be picked up from blood in the glomerulus.
Protection of transplant-induced renal ischemia-reperfusion injury with carbon monoxide
Authors: Neto Joao Seda , Nakao Atsunori , Kimizuka Kei , Romanosky Anna Jeanine , Stolz Donna B. , Uchiyama Takashi , Nalesnik Michael A. , Otterbein Leo E. , Murase Noriko
Published: August 2004

Carbon monoxide (CO), a product of heme metabolism by heme oxygenases, is known to impart protection against oxidative stress. We hypothesized that CO would protect ischemia-reperfusion (I/R) injury of transplanted organs, and the efficacy of CO was studied in the rat kidney transplantation model. A Lewis rat kidney graft, preserved in University of Wisconsin solution at 4°C for 24 h, was orthotopically transplanted into syngeneic rats. Recipients were maintained in room air or exposed to CO (250 ppm) in air for 1 h before and 24 h after transplantation. Animals were killed 1, 3, 6, and 24 h after transplantation to assess efficacy of inhaled CO. Rapid upregulation of mRNA for IL-6, IL-1β, TNF-α, ICAM-1, heme oxygenase-1, and inducible nitric oxide synthase was observed within 3 h after transplantation in the control grafts of air-exposed recipients, associating with histopathological evidences of acute tubular necrosis, interstitial hemorrhage, and edema. In contrast, the increase of inflammatory mediators was markedly inhibited in kidney grafts of CO-treated recipients, which correlated with improved renal cortical blood flow. Further detailed morphological analyses revealed that CO preserved the glomerular vascular architecture and podocyte viability with less apoptosis of tubular epithelial cells and less ED1+macrophage infiltration. CO inhalation resulted in improved serum creatinine levels and clearance, and animal survival was significantly improved with CO to 60.5 from 25 days in untreated controls. The study demonstrates that exposure of kidney graft recipients to CO at a low concentration can impart significant protective effects against renal I/R injury and improve function of renal grafts.
The Cl−/HCO3−exchanger pendrin in the rat kidney is regulated in response to chronic alterations in chloride balance
Authors: Quentin Fabienne , Chambrey Régine , Trinh-Trang-Tan Marie Marcelle , Fysekidis Marinos , Cambillau Michèle , Paillard Michel , Aronson Peter S. , Eladari Dominique
Published: August 2004

Pendrin (Pds; Slc26A4) is a new anion exchanger that is believed to mediate apical Cl−/HCO3−exchange in type B and non-A-non-B intercalated cells of the connecting tubule and cortical collecting duct. Recently, it has been proposed that this transporter may be involved in NaCl balance and blood pressure regulation in addition to its participation in the regulation of acid-base status. The purpose of our study was to determine the regulation of Pds protein abundance during chronic changes in chloride balance. Rats were subjected to either NaCl, NH4Cl, NaHCO3, KCl, or KHCO3loading for 6 days or to a low-NaCl diet or chronic furosemide administration. Pds protein abundance was estimated by semiquantitative immunoblotting in renal membrane fractions isolated from the cortex of treated and control rats. We observed a consistent inverse relationship between Pds expression and diet-induced changes in chloride excretion independent of the administered cation. Conversely, NaCl depletion induced by furosemide was associated with increased Pds expression. We conclude that Pds expression is specifically regulated in response to changes in chloride balance.
Cell density-dependent expression of EDG family receptors and mesangial cell proliferation: role in lysophosphatidic acid-mediated cell growth
Authors: Xing Yiding , Ganji Shobha H. , Noh Jung W. , Kamanna Vaijinath S.
Published: August 2004

Lysophosphatidic acid (LPA), a major member of the bioactive lysophospholipids in serum, possesses diverse physiological activities including cell proliferation. Recently, three endothelial differentiation gene (EDG) family receptors, including EDG-2 (LPA1), EDG-4 (LPA2), and EDG-7 (LPA3), have been identified as LPA receptors. The role of LPA and their receptors in mesangial cell physiology is not clearly understood. This study examined the expression profile of EDG receptors as a function of cell density and the participation of EDG receptors in human mesangial cell proliferation by LPA. We showed that mesangial cells express all three EDG family LPA receptors in a cell density-dependent manner. EDG-7 maximally expressed at sparse cell density and minimally expressed in dense cell population. The EDG-2 expression pattern was opposite to the EDG-7. No changes in EDG-4 expression as a function of cell density were noted. DNA synthetic rate was greater in sparse cell density compared with dense cell population and followed a similar pattern with EDG-7 expression. Comparative studies in sparse and dense cell density indicated that EDG-7 was positively associated, whereas EDG-2 was negatively associated with cell proliferation rate. LPA induced mesangial cell proliferation by 1.5- to 3.5-fold. Dioctanoylglycerol pyrophosphate, an antagonist for EDG-7, almost completely inhibited mesangial cell proliferation induced by LPA. We suggest that EDG-7 regulates LPA-mediated mesangial cell proliferation. Additionally, these data suggest that EDG-7 and EDG-2 LPA receptors play a diverse role as proliferative and antiproliferative, respectively, in mesangial cells. Regulation of EDG family receptors may be importantly linked to mesangial cell-proliferative processes.
Opioid-Like Actions of Neuropeptide Y in Rat Substantia Gelatinosa: Y1 Suppression of Inhibition and Y2 Suppression of Excitation
Authors: Moran Timothy D. , Colmers William F. , Smith Peter A.
Published: August 2004

Neuropathic pain that results from injury to the peripheral or CNS responds poorly to opioid analgesics. Y1 and Y2 receptors for neuropeptide Y (NPY) may, however, serve as targets for analgesics that retain their effectiveness in neuropathic pain states. In substantia gelatinosa neurons in spinal cord slices from adult rats, we find that NPY acts via presynaptic Y2 receptors to attenuate excitatory postsynaptic currents (EPSCs) and predominantly on presynaptic Y1 receptors to attenuate glycinergic and GABAergic inhibitory postsynaptic currents (IPSCs). Because NPY attenuates the frequency of TTX-resistant miniature EPSCs and IPSCs, perturbation of the neurotransmitter release process contributes to its actions at both excitatory and inhibitory synapses. These effects, which are reminiscent of those produced by analgesic opioids, provide a cellular basis for previously documented spinal analgesic actions mediated via Y1 and Y2 receptors in neuropathic pain paradigms. They also underline the importance of suppression of inhibition in spinal analgesic mechanisms.
Very Fast Oscillations Evoked by Median Nerve Stimulation in the Human Thalamus and Subthalamic Nucleus
Authors: Hanajima Ritsuko , Chen Robert , Ashby Peter , Lozano Andres M. , Hutchison William D. , Davis Karen D. , Dostrovsky Jonathan O.
Published: August 2004

Very fast oscillations (VFOs; 500–1,500 Hz) are associated with sensory-evoked potentials (SEPs), but their origin is unknown. To characterize the origins of VFOs, we studied 35 patients with deep brain stimulation (DBS) electrodes [15 with thalamic and 20 with the subthalamic nucleus (STN) electrodes]. We recorded median nerve stimulation–evoked SEPs from the thalamus and STN with microelectrodes during stereotactic surgery and from the contacts of the DBS electrodes postoperatively. We also examined the firing of individual neurons in thalamus in relation to the VFOs. In the thalamus, VFOs with frequencies around 1,000 Hz were superimposed on slow potentials. Both slow and fast SEP components showed phase reversals in the somatosensory thalamus [ventralis caudalis (Vc)]. Median nerve poststimulus time histograms showed that single thalamic neurons fired at preferred times at intervals between 0.8 to 1.2 ms that were synchronous with the VFOs, although the neurons fired only once or a few times per trial. In the STN, low-amplitude SEPs with VFOs were observed at a latency similar to the thalamic SEPs. The VFOs from STN probably represent volume conduction, possibly from the medial lemniscus. We conclude that the thalamic VFOs are generated within Vc and that they induce time-locked firing in a network of neurons.
Control of Dynamic Stability During Gait Termination on a Slippery Surface
Authors: Oates A. R. , Patla A. E. , Frank J. S. , Greig M. A.
Published: August 2004

There are three common ways by which to successfully terminate gait: decreased acceleration of whole-body center of mass (COM) through a flexor synergy in the trail leg, increased deceleration of whole-body COM through an extensor synergy in the front limb, and an energy/momentum transfer to dissipate any remaining momentum if the first two strategies are unsuccessful. Healthy individuals were asked to stop on a slippery surface while we examined their unexpected response to the slippery surface. Kinetic data from the forceplates revealed lower braking forces in the slip trials compared with normal gait-termination trials. Subjects were unable to control their center of pressure (COP) to manipulate the COM as revealed by increased deviations and maximum absolute ranges of COP movement. Subject COM deviated farther in both horizontal planes and lowered further during the slip compared with normal gait-termination trials. Arm movements were effective in dissipating forward COM movement. In addition, there likely was a transfer of forward to lateral momentum to stop forward progression. All recorded muscle activity in the lower limbs and back increased during the slip to provide support to the lower limbs and correct upright balance. The trailing limb shortened its final step to provide support to the lowering COM. The balance-correction response seen here resembles previous reactions to perturbations during locomotion suggesting there is a generalized strategy employed by the nervous system to correct for disturbances and maintain balance.
Microarray analysis of gene expression after transverse aortic constriction in mice
Authors: Zhao Mingming , Chow Amy , Powers Jennifer , Fajardo Giovanni , Bernstein Daniel
Published: August 2004

Cardiac hypertrophy is a compensatory response initially beneficial to heart function but can ultimately lead to cardiac decompensation. It is an integrated process involving multiple cellular signaling pathways and their cross talk. Microarray GeneChip technology is a powerful new tool to identify gene expression profiles of cardiac hypertrophy. To identify well-characterized as well as novel adaptive mechanisms, we utilized a murine model of compensated pressure overload hypertrophy (transverse aortic constriction, TAC). At 48 h, 10 days, and 3 wk, hearts were harvested and total RNA hybridized to Affymetrix U74Av2 GeneChips, which contain a 12,488-gene/EST probe set. Verification of gene expression was performed by SYBR quantitative real-time RT-PCR (QRT-PCR) for selected genes. A rigorous evaluation of the adequacy of the control condition was also performed. For statistical analysis we generated a four-step filtering criteria. Our results show an upregulation of 38 genes (48 h), 269 genes (10 days), and 203 genes (3 wk) and downregulation of 15 genes (48 h), 160 genes (10 days), and 124 genes (3 wk). Transcripts differentially expressed after TAC were categorized into 12 functional groups and revealed the presence of several intriguing transcripts, e.g., cell proliferation-related Ki-67 and several apoptosis-related genes. Overall changes in QRT-PCR were in accordance with GeneChip data, with the highest correlation for genes with the largest up- or downregulation with TAC. Thus TAC results in altered expression of genes in several pathways regulating both cardiac structure and function. However, for in vivo gene microarray experiments, it is critical to define adequate controls, perform rigorous statistical analysis, and provide validation by alternative methods.
Trappin ovine molecule (TOM), the ovine ortholog of elafin, is an acute phase reactant in the lung
Authors: Brown Thomas I. , Mistry Rohit , Collie D. David , Tate Steven , Sallenave Jean-Michel
Published: August 2004

As large animal models continue to play an important role in translating lung-directed therapeutic strategies from laboratory animals to humans, there is an increasing interest in the analysis of endogenous regulators of inflammation at both a genomic and a therapeutic level. To this end, we have sought to characterize the ovine ortholog of elafin, an important regulator of inflammation in humans. We have isolated both the elafin cDNA and gene, which have a similar structure to other species’ orthologs. Interestingly, we have isolated two alleles for ovine elafin, which contain a very high number of transglutamination repeats, thought to be important in binding elafin to the interstitium. The mainly mucosal mRNA distribution for ovine elafin suggests that ovine elafin may, like its human ortholog, have functions in innate immunity. This is supported by analysis of elafin and the related protein secretory leukocyte protease inhibitor (SLPI) in ovine bronchoalveolar fluid in response to locally administered lipopolysaccharide and confirmation of them acting as “alarm” antiproteases. We have also cloned the ovine elafin cDNA into an adenoviral vector and have demonstrated correct processing of the secreted protein as well as biological activity. Overexpression of ovine elafin in a lung-derived epithelial cell line has a protective effect against the enzymes human neutrophil and porcine pancreatic elastase. The identification of the ovine elafin gene and its translated protein are important in developing practical strategies aimed at regulating inflammation in the large mammalian lung.
Dermal papilla-induced hair differentiation of adult epithelial stem cells from human skin
Authors: Roh Cecilia , Tao Qingfeng , Lyle Stephen
Published: August 2004

The epithelial-mesenchymal interactions between keratinocyte stem cells and dermal papilla (DP) cells are crucial for normal development of the hair follicle as well as during hair cycling. During the cyclical regrowth of a new lower follicle, the multipotent hair follicle stem cells are stimulated to proliferate and differentiate through interactions with the underlying mesenchymal DP cells. To characterize the events occurring during the process of epithelial stem cell fate determination, we utilized a coculture system by incubating human hair follicle keratinocyte stem cells with DP cells. Using GeneChip microarrays, we analyzed changes in gene expression within the stem cells upon coculture with the DP over a 5-day time course. A number of important signaling pathways and growth factors were regulated. The hair-specific keratin 6hf (K6hf) gene proved a particularly good marker of hair differentiation, with a 7.9-fold increase in mRNA and resulting increased protein levels. The high expression of K6hf was unique to DP-induced keratinocyte differentiation, since expression of K6hf was not induced by high calcium. Since the β-catenin signaling pathway has been implicated in hair follicle development, we examined the role of β-catenin in our system and demonstrated that β-catenin/lef-1 signaling is required for DP-induced hair differentiation.
Flowing cells through pulsed electric fields efficiently purges stem cell preparations of contaminating myeloma cells while preserving stem cell function
Authors: Craiu Abie , Saito Yoriko , Limon Ana , Eppich Henry M. , Olson Douglas P. , Rodrigues Neil , Adams Gregor B. , Dombkowski David , Richardson Paul , Schlossman Robert , Choi Peter S. , Grogins Jonathan , O'Connor Paula G. , Cohen Kenneth , Attar Eyal C. , Freshman Jay , Rich Rebecca , Mangano Joseph A. , Gribben John G. , Anderson Kenneth C. , Scadden David T.
Published: August 2004

Autologous stem cell transplantation, in the setting of hematologic malignancies such as lymphoma, improves disease-free survival if the graft has undergone tumor purging. Here we show that flowing hematopoietic cells through pulsed electric fields (PEFs) effectively purges myeloma cells without sacrificing functional stem cells. Electric fields can induce irreversible cell membrane pores in direct relation to cell diameter, an effect we exploit in a flowing system appropriate for clinical scale. Multiple myeloma (MM) cell lines admixed with human bone marrow (BM) or peripheral blood (PB) cells were passed through PEFs at 1.35 kV/cm to 1.4 kV/cm, resulting in 3- to 4-log tumor cell depletion by flow cytometry and 4.5- to 6-log depletion by tumor regrowth cultures. Samples from patients with MM gave similar results by cytometry. Stem cell engraftment into nonobese diabetic–severe combined immunodeficient (NOD/SCID)/β2m-/- mice was unperturbed by PEFs. Flowing cells through PEFs is a promising technology for rapid tumor cell purging of clinical progenitor cell preparations.
Enhanced tumorigenesis in HTLV-1 Tax-transgenic mice deficient in interferon-gamma
Authors: Mitra-Kaushik Shibani , Harding John , Hess Jay , Schreiber Robert , Ratner Lee
Published: August 2004

The oncoprotein Tax of human T-cell leukemia virus type I (HTLV-1) is the major mediator of viral pathogenesis in infected individuals. Expression of Tax under the regulation of the human granzyme B promoter in mice results in a lymphoproliferative disorder resembling adult T-cell leukemia/lymphoma (ATL). Tax expression is associated with the production of high levels interferon-γ (IFN-γ) in HTLV-1-infected CD4+ cells and Tax-transgenic tumors. We examined the role of IFN-γ in tumorigenesis, by mating Tax-transgenic mice with a gene-specific knockout for IFN-γ. IFN-γ-/- Tax+-transgenic mice show accelerated tumor onset (median, 4 versus 6 months), dissemination (median, 5 versus 7 months), and death (median, 7 versus 10 months), compared with IFN-γ+/- or IFN-γ+/+ Tax+ mice. Pathologic and immunophenotypic characteristics of tumors from all genotypes are indistinguishable, except for enhanced interleukin 2 receptor-β (IL-2Rβ) and suppressed intercellular adhesion molecule-1 (ICAM-1) expression on tumors from IFN-γ-/- Tax+ transgenic mice. IFN-γ-/- tumors demonstrate enhanced CD31 (platelet-endothelial CAM-1 [PECAM-1]) staining compared with those from IFN-γ+/- or IFN-γ+/+ Tax+ mice. Angiogenesis-specific cDNA microarray analysis identified 4 mediators of angiogenic growth differentially expressed in tumors from Tax+IFN-γ-/- mice compared with Tax+IFN-γ+/+ littermates. As confirmed by reverse transcription-polymerase chain reaction (RT-PCR), loss of IFN-γ results in down-regulation of tumor necrosis factor-α (TNF-α) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) while up-regulating expression of vascular endothelial growth factor (VEGF) and tenascin C. These results provide insight into a possible mechanism by which IFN-γ contributes to host resistance against HTLV-induced tumors through an angiostatic effect. (Blood. 2004;104:3305-3311)