bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of sex and chronic resistance training on human patellar tendon dry mass, collagen content, and collagen cross-linking
Authors: LeMoine Jennifer K. , Lee Jonah D. , Trappe Todd A.
Published: October 2008

Collagen content and cross-linking are believed to be major determinants of tendon structural integrity and function. Sex and chronic resistance training have been shown to alter tendon function and may also alter the key structural features of tendon. Patellar tendon biopsies were taken from untrained men [ n = 8, 1 repetition maximum (RM) = 53 ± 3 kg], untrained women ( n = 8, 1 RM = 29 ± 2 kg), and resistance-trained (10 ± 1 yr of training) men ( n = 8, 1 RM = 71 ± 6 kg). Biopsies were analyzed for dry mass, collagen content, and collagen cross-linking (hydroxylysylpyridinoline). We hypothesized that these elements of tendon structure would be lower in women than men, whereas chronic resistance training would increase these parameters in men. Tendon dry mass was significantly lower in women than men (343 ± 5 vs. 376 ± 8 μg dry mass/mg tendon wet wt, P < 0.01) and was not influenced by chronic resistance training ( P > 0.05). The lower tendon dry mass in women tended to reduce ( P = 0.08) collagen content per tendon wet weight. Collagen content of the tendon dry mass was not influenced by sex or resistance training ( P > 0.05). Similarly, cross-linking of collagen was unaltered ( P > 0.05) by sex or training. Although sex alters the water content of patellar tendon tissue, any changes in tendon function with sex or chronic resistance training in men do not appear to be explained by alterations in collagen content or cross-linking of collagen within the dry mass component of the tendon.
Phagocyte migration and cellular stress induced in liver, lung, and intestine during sleep loss and sleep recovery
Authors: Everson Carol A. , Thalacker Christa D. , Hogg Neil
Published: October 2008

Sleep is understood to possess recuperative properties and, conversely, sleep loss is associated with disease and shortened life span. Despite these critical attributes, the mechanisms and functions by which sleep and sleep loss impact health still are speculative. One of the most consistent, if largely overlooked, signs of sleep loss in both humans and laboratory rats is a progressive increase in circulating phagocytic cells, mainly neutrophils. The destination, if any, of the increased circulating populations has been unknown and, therefore, its medical significance has been uncertain. The purpose of the present experiment was to determine the content and location of neutrophils in liver and lung tissue of sleep-deprived rats. These are two principal sites affected by neutrophil migration during systemic inflammatory illness. The content of neutrophils in the intestine also was determined. Sleep deprivation in rats was produced for 5 and 10 days by the Bergmann-Rechtschaffen disk method, which has been validated for its high selectivity under freely moving conditions and which was tolerated and accompanied by a deep negative energy balance. Comparison groups included basal conditions and 48 h of sleep recovery after 10 days of sleep loss. Myeloperoxidase (MPO), an enzyme constituent of neutrophils, was extracted from liver, lung, and intestinal tissues, and its activity was determined by spectrophotometry. Leukocytes were located in vasculature and interstitial spaces in the liver and the lung by immunohistochemistry. Heme oxygenase-1, also known as heat shock protein-32 and a marker of cellular stress, and corticosterone also were measured. The results indicate neutrophil migration into extravascular liver and lung tissue concurrent with cell stress and consistent with tissue injury or infection induced by sleep loss. Plasma corticosterone was unchanged. Recovery sleep was marked by increased lung heme oxygenase-1, increased intestinal MPO activity, and abnormally low corticosterone, suggesting ongoing reactive processes as a result of prior sleep deprivation.
Inhibitory effects and mechanisms of intestinal electrical stimulation on gastric tone, antral contractions, pyloric tone, and gastric emptying in dogs
Authors: Zhao Xiaotuan , Yin Jieyun , Chen Jihong , Song Gengqing , Wang Lijie , Zhu Hongbing , Brining Doug , Chen Jiande D. Z.
Published: October 2008

The aim of this study was to investigate the effects and mechanisms of intestinal electrical stimulation (IES) on gastric tone, antral and pyloric contractions, and gastric emptying in dogs. Female hound dogs were equipped with a duodenal or gastric cannula, and one pair of serosal electrodes was implanted in the small intestine. The study consisted of five different experiments. Liquid gastric emptying was assessed by collection of chyme from the duodenal cannula in a number of sessions with and without IES and with and without N-nitro-l-arginine (l-NNA). Postprandial antral and pyloric contractions were measured with and without IES and in the absence and presence of l-NNA or phentolamine by placement of a manometric catheter into the antrum and pylorus via the duodenal cannula. Gastric tone was assessed by measurement of gastric volume at a constant pressure. Gastric emptying was substantially and significantly delayed by IES or l-NNA compared with the control session. IES-induced delay of gastric emptying became normal with addition of l-NNA. IES reduced gastric tone, which was blocked by l-NNA. IES also inhibited antral contractions (frequency and amplitude), and this inhibitory effect was not blocked by l-NNA but was blocked by phentolamine. IES alone did not affect pyloric tone or resistance, but IES + l-NNA decreased pyloric tone. In conclusion, IES reduces gastric tone via the nitrergic pathway, inhibits antral contractions via the adrenergic pathway, does not affect pyloric tone, and delays liquid gastric emptying. IES-induced delay of gastric emptying is attributed to its inhibitory effects on gastric motility.
A haplotype of human angiotensinogen gene containing −217A increases blood pressure in transgenic mice compared with −217G
Authors: Jain Sudhir , Vinukonda Govindaiah , Fiering Steven N. , Kumar Ashok
Published: October 2008

The human angiotensinogen (hAGT) gene contains an A/G polymorphism at −217, and frequency of −217A allele is increased in African-American hypertensive patients. The hAGT gene has seven polymorphic sites in the 1.2-kb region of its promoter, and variant −217A almost always occurs with −532T, −793A, and −1074T, whereas variant −217G almost always occurs with −532C, −793G, and −1074G. Since allele −6A is the predominant allele in African-Americans, the AGT gene can be subdivided into two main haplotypes, −6A:−217A (AA) and −6A:−217G (AG). To understand the role of these haplotypes on hAGT gene expression and on blood pressure regulation in an in vivo situation, we have generated double transgenic mice containing human renin gene and either AA or AG haplotype of the hAGT gene using knock-in strategy at the hypoxanthine phosphoribosyltransferase locus. We show here that 1) hAGT mRNA level is increased in the liver by 60% and in the kidney by 40%; and 2) plasma AGT level is increased by ∼40%, and plasma angiotensin II level is increased by ∼50% in male double transgenic mice containing AA haplotype of the hAGT gene compared with the AG haplotype. In addition, systolic blood pressure is increased by 8 mmHg in transgenic mice containing the AA haplotype compared with the AG haplotype. This is the first report to show the effect of polymorphisms in the promoter of a human gene on its transcription in an in vivo situation that ultimately leads to an increase in blood pressure.
Sprouting of substance P-expressing primary afferent central terminals and spinal micturition reflex NK1 receptor dependence after spinal cord injury
Authors: Zhang Xiaoyang , Douglas Kristy L. , Jin Huixia , Eldaif Bassem M. , Nassar Rashid , Fraser Matthew O. , Dolber Paul C.
Published: October 2008

The primary afferent neurotransmitter triggering the spinal micturition reflex after complete spinal cord injury (SCI) in the rat is unknown. Substance P detected immunohistochemically in the sacral parasympathetic nucleus was significantly higher in 12 SCI rats than in 12 spinally intact rats ( P = 0.008), suggesting substance P as a plausible candidate for the primary afferent neurotransmitter. The effects of the tachykinin NK1 receptor antagonist L-733060 on the spinal micturition reflex were then determined by performing conscious cystometry in an additional 14 intact rats and 14 SCI rats with L-733060 (0.1–100 μg) administered intrathecally at L6-S1. L-733060 was without effect in intact rats, but blocked the spinal micturition reflex in 10 of 14 SCI rats and increased the intermicturition interval in 2 of 4 others at doses ranging from 10 to 100 μg. Both phasic and nonphasic voiding contractions, differentiated according to the presence of phasic external urethral sphincter (EUS) activity, were present in most SCI rats. Both types of contractions were blocked by high doses of L-733060. Interestingly, there was a relative decline in phasic voiding contractions at high doses as well as a decline in contraction amplitude in nonphasic voiding contractions. In other respects, cystometric variables were largely unaffected in either spinally intact or SCI rats. L-733060 did not affect tonic EUS activity at any dose except when the spinal micturition reflex was blocked and tonic activity was consequently lost. These experiments show that tachykinin action at spinal NK1 receptors plays a major role in the spinal micturition reflex in SCI rats.
Hypoxia-inducible carbonic anhydrase IX expression is insufficient to alleviate intracellular metabolic acidosis in the muscle of zebrafish,Danio rerio
Authors: Esbaugh Andrew J. , Perry S. F. , Gilmour K. M.
Published: October 2008

Recent evidence suggests that carbonic anhydrase (CA) IX in humans is under the regulatory control of hypoxia-inducible factor and is overexpressed in certain cancers. However, little is known of its presence in nonmammalian vertebrates or its physiological function in any vertebrate. The objective of this study was to examine and characterize the presence, distribution, induction by hypoxia, and physiological function of CA IX in the zebrafish. Zebrafish CA IX was highly expressed in the eye, brain, and gastrointestinal tract and showed increased expression in the eye, brain, and muscle in response to hypoxia (water Po2= 24 mmHg). The hypothesis that increased CA IX expression during hypoxia would act to attenuate intracellular acidosis was then examined. Muscle intracellular pH (pHi) decreased after 4 h of hypoxic exposure (from 7.15 ± 0.02 to 7.06 ± 0.01 pH units) and did not recover by 24 h. Manipulation of extracellular CA activity via intraperitoneal injection of either bovine CA or the selective extracellular CA inhibitor F3500 revealed that although increased CA activity could fully restore pHi, removal of extracellular activity did not result in further acidosis. An exercise-induced acidosis was also attenuated in fish treated with bovine CA; however, the increased extracellular CA expression resulting from hypoxia had no affect. These data suggest that although extracellular CA can potentially minimize the impact of hypoxia on muscle pHi, the actual level of extracellular CA activity is likely insufficient to achieve this goal, even when enhanced by hypoxia-induced increases in CA IX expression.
Phosphocreatine recovery kinetics following low- and high-intensity exercise in human triceps surae and rat posterior hindlimb muscles
Authors: Forbes Sean C. , Paganini Anthony T. , Slade Jill M. , Towse Theodore F. , Meyer Ronald A.
Published: October 2008

Previous studies have suggested the recovery of phosphocreatine (PCr) after exercise is at least second-order in some conditions. Possible explanations for higher-order PCr recovery kinetics include heterogeneity of oxidative capacity among skeletal muscle fibers and ATP production via glycolysis contributing to PCr resynthesis. Ten human subjects (28 ± 3 yr; mean ± SE) performed gated plantar flexion exercise bouts consisting of one contraction every 3 s for 90 s (low-intensity) and three contractions every 3 s for 30 s (high-intensity). In a parallel gated study, the sciatic nerve of 15 adult male Sprague-Dawley rats was electrically stimulated at 0.75 Hz for 5.7 min (low intensity) or 5 Hz for 2.1 min (high intensity) to produce isometric contractions of the posterior hindlimb muscles. [31P]-MRS was used to measure relative [PCr] changes, and nonnegative least-squares analysis was utilized to resolve the number and magnitude of exponential components of PCr recovery. Following low-intensity exercise, PCr recovered in a monoexponential pattern in humans, but a higher-order pattern was typically observed in rats. Following high-intensity exercise, higher-order PCr recovery kinetics were observed in both humans and rats with an initial fast component (τ < 15 s) resolved in the majority of humans (6/10) and rats (5/8). These findings suggest that heterogeneity of oxidative capacity among skeletal muscle fibers contributes to a higher-order pattern of PCr recovery in rat hindlimb muscles but not in human triceps surae muscles. In addition, the observation of a fast component following high-intensity exercise is consistent with the notion that glycolytic ATP production contributes to PCr resynthesis during the initial stage of recovery.
Insulin, leptin, and food reward: update 2008
Authors: Figlewicz Dianne P. , Benoit Stephen C.
Published: October 2008

The hormones insulin and leptin have been demonstrated to act in the central nervous system (CNS) as regulators of energy homeostasis at medial hypothalamic sites. In a previous review, we described new research demonstrating that, in addition to these direct homeostatic actions at the hypothalamus, CNS circuitry that subserves reward and motivation is also a direct and an indirect target for insulin and leptin action. Specifically, insulin and leptin can decrease food reward behaviors and modulate the function of neurotransmitter systems and neural circuitry that mediate food reward, i.e., midbrain dopamine and opioidergic pathways. Here we summarize new behavioral, systems, and cellular evidence in support of this hypothesis and in the context of research into the homeostatic roles of both hormones in the CNS. We discuss some current issues in the field that should provide additional insight into this hypothetical model. The understanding of neuroendocrine modulation of food reward, as well as food reward modulation by diet and obesity, may point to new directions for therapeutic approaches to overeating or eating disorders.
Delayed and acute effects of interferon-γ on activity of an inwardly rectifying K+ channel in cultured human proximal tubule cells
Authors: Nakamura Kazuyoshi , Komagiri You , Kojo Toshiyuki , Kubokawa Manabu
Published: October 2008

The activity of an inwardly rectifying K+ channel in cultured human renal proximal tubule cells (RPTECs) is stimulated and inhibited by nitric oxide (NO) at low and high concentrations, respectively. In this study, we investigated the effects of IFN-γ, one of the cytokines which affect the expression of inducible NO synthase (iNOS), on intracellular NO and channel activity of RPTECs, using RT-PCR, NO imaging, and the cell-attached mode of the patch-clamp technique. Prolonged incubation (24 h) of cells with IFN-γ (20 ng/ml) enhanced iNOS mRNA expression and NO production. In these cells, a NOS inhibitor, Nω-nitro-l-arginine methyl ester (l-NAME; 100 μM), elevated channel activity, suggesting that NO production was so high as to suppress the channel. This indicated that IFN-γ would chronically suppress channel activity by enhancing NO production. Acute effects of IFN-γ was also examined in control cells. Simple addition of IFN-γ (20 ng/ml) to the bath acutely stimulated channel activity, which was abolished by inhibitors of IFN-γ receptor-associated Janus-activated kinase [P6 (1 μM) and AG490 (10 μM)]. However, l-NAME did not block the acute effect of IFN-γ. Indeed, IFN-γ did not acutely affect NO production. Moreover, the acute effect was not blocked by inhibition of PKA, PKG, and phosphatidylinositol 3-kinase (PI3K). We conclude that IFN-γ exerted a delayed suppressive effect on K+ channel activity by enhancing iNOS expression and an acute stimulatory effect, which was independent of either NO pathways or phosphorylation processes mediated by PKA, PKG, and PI3K in RPTECs.
Parathyroid hormone decreases endothelial osteoprotegerin secretion: role of protein kinase A and C
Authors: Rashid Gloria , Plotkin Eleanora , Klein Osnat , Green Janice , Bernheim Jacques , Benchetrit Sydney
Published: October 2008

Parathyroid hormone (PTH), which is elevated in patients with chronic renal failure, has been shown to participate in the development of vascular calcification. Previous studies have demonstrated that PTH may promote endothelial expressions of proinflammatory parameters. On the basis of these data, we evaluated whether PTH may have an impact on endothelial osteoprotegerin (OPG), a vascular-protective factor which may control vascular calcification. Endothelial cells were stimulated with 10−12to 10−10mol/l PTH. PKC and PKA are the main cellular pathways of PTH. Inhibitors and activators of PKC or PKA were used to determine whether these signaling pathways are involved in the control of endothelial OPG. PTH induced a decrease in OPG secretion and mRNA expression. Treatment of PTH-stimulated cells by calphostin C (PKC inhibitor) induced a further decrease in OPG secretion, while Rp-cAMP (PKA inhibitor) had no additional effect. In nonstimulated cells, a PKC activator significantly stimulated OPG secretion, while a PKA activator was associated with a decline. These effects were blunted in the presence of calphostin C and Rp-cAMP, respectively. An increase in OPG secretion induced by a PKC activator indicates that the basal OPG secretion is mediated through PKC. The decrease induced by a PKA activator, which is similar to the decrease observed with PTH, suggests that the action of PTH on OPG secretion and mRNA expression may be due to the PKA pathway.
A nectar-feeding mammal avoids body fluid disturbances by varying renal function
Authors: Hartman Bakken Bradley , Herrera M. L. Gerardo , Carroll Robert M. , Ayala-Berdón Jorge , Schondube Jorge E. , Martínez del Rio Carlos
Published: October 2008

To maintain water and electrolyte balance, nectar-feeding vertebrates oscillate between two extremes: avoiding overhydration when feeding and preventing dehydration during fasts. Several studies have examined how birds resolve this osmoregulatory dilemma, but no data are available for nectar-feeding mammals. In this article, we 1) estimated the ability of Pallas's long-tongued bats ( Glossophaga soricina; Phyllostomidae) to dilute and concentrate urine and 2) examined how water intake affected the processes that these bats use to maintain water balance. Total urine osmolality in water- and salt-loaded bats ranged between 31 ± 37 mosmol/kgH2O ( n = 6) and 578 ± 56 mosmol/kgH2O ( n = 2), respectively. Fractional water absorption in the gastrointestinal tract was not affected by water intake rate. As a result, water flux, body water turnover, and renal water load all increased with increasing water intake. Despite these relationships, glomerular filtration rate (GFR) was not responsive to water loading. To eliminate excess water, Pallas's long-tongued bats increased water excretion rate by reducing fractional renal water reabsorption. We also found that rates of total evaporative water loss increased with increasing water intake. During their natural daytime fast, mean GFR in Pallas's long-tongued bats was 0.37 ml/h ( n = 10). This is ∼90% lower than the GFR we measured in fed bats. Our findings 1) suggest that Pallas's long-tongued bats do not have an exceptional urine-diluting or -concentrating ability and 2) demonstrate that the bats eliminate excess ingested water by reducing renal water reabsorption and limit urinary water loss during fasting periods by reducing GFR.
Acid loading in vivo and low pH in culture increase angiotensin receptor expression: enhanced ammoniagenic response to angiotensin II
Authors: Nagami Glenn T. , Chang Jenny A. , Plato Megan E. , Santamaria Rafael
Published: October 2008

The proximal tubule defends the body against acid challenges by enhancing its production and secretion of ammonia. Our previous studies demonstrated an enhanced ammoniagenic response of the proximal tubule to ANG II added to the lumen in vitro after an in vivo acid challenge. The present study examined the effect of NH4Cl acid loading in vivo on renal cortical type 1 ANG II (AT1) receptor expression, the effect of low pH on AT1receptor expression in a proximal tubule cells in culture, and their response to ANG II. A short-term (18 h) NH4Cl load in vivo resulted in increased renal cortical AT1receptor mRNA expression and increased brush-border membrane AT1receptor protein expression levels. Changing the cell culture pH from 7.4 to 7.0 for at least 2 h increased cell surface expression of AT1receptors and enhanced the stimulatory effect of ANG II on ammonia production rates. This increased ammoniagenic response to ANG II and the early enhancement of cell surface expression induced by exposure of the cultured proximal tubule cells to pH 7.0 were prevented by treatment with colchicine. These results suggest that, after acid challenges, the enhanced ammoniagenic response of the proximal tubule to ANG II is, in part, mediated by increased AT1receptor cell surface expression and that the enhancement of receptor expression plays an important role in the early response of the proximal tubule to acid challenges.
Chronic ouabain treatment induces vasa recta endothelial dysfunction in the rat
Authors: Cao Chunhua , Payne Kristie , Lee-Kwon Whaseon , Zhang Zhong , Lim Sun Woo , Hamlyn John , Blaustein Mordecai P. , Kwon H. Moo , Pallone Thomas L.
Published: October 2008

Descending vasa recta (DVR) are 15-μm vessels that perfuse the renal medulla. Ouabain has been shown to augment DVR endothelial cytoplasmic Ca2+ ([Ca2+]CYT) signaling. In this study, we examined the expression of the ouabain-sensitive Na-K-ATPase α2 subunit in the rat renal vasculature and tested effects of acute ouabain exposure and chronic ouabain treatment on DVR. Immunostaining with antibodies directed against the α2 subunit verified its expression in both DVR pericytes and endothelium. Acute application of ouabain (100 or 500 nM) augmented the DVR nitric oxide generation stimulated by acetylcholine (ACh; 10 μM). At a concentration of 1 mM, ouabain constricted microperfused DVR, whereas at 100 nM, it was without effect. Acute ouabain (100 nM) did not augment constriction by angiotensin II (0.5 or 10 nM), whereas l-nitroarginine methyl ester-induced contraction of DVR was slightly enhanced. Ouabain-hypertensive (OH) rats were generated by chronic ouabain treatment (30 μg·kg−1·day−1, 5 wk). The acute endothelial [Ca2+]CYT elevation by ouabain (100 nM) was absent in DVR endothelia of OH rats. The [Ca2+]CYT response to 10 nM ACh was also eliminated, whereas the response to 10 μM ACh was not. The endothelial [Ca2+]CYT response to bradykinin (100 nM) was significantly attenuated. We conclude that endothelial responses may offset the ability of acute ouabain exposure to enhance DVR vasoconstriction. Chronic exposure to ouabain, in vivo, leads to hypertension and DVR endothelial dysfunction, manifested as reduced [Ca2+]CYT responses to both ouabain- and endothelium-dependent vasodilators.
ATP-sensitive K+channels in pig urethral smooth muscle cells are heteromultimers of Kir6.1 and Kir6.2
Authors: Teramoto Noriyoshi , Zhu Hai-Lei , Shibata Atsushi , Aishima Manami , Walsh Emma J. , Nagao Masaya , Cole William C.
Published: October 2008

The inwardly rectifying properties and molecular basis of ATP-sensitive K+channels (KATPchannels) have now been established for several cell types. However, these aspects of nonvascular smooth muscle KATPchannels still remain to be defined. In this study, we investigated the molecular basis of the pore of KATPchannels of pig urethral smooth muscle cells through a comparative study of the inwardly rectifying properties, conductance, and regulation by PKC of native and homo- and heteroconcatemeric recombinant Kir6.x channels coexpressed with sulfonylurea receptor subunit SUR2B in human embryonic kidney (HEK) 293 cells by the patch-clamp technique (conventional whole-cell and cell-attached modes). In conventional whole-cell clamp recordings, levcromakalim (≥1 μM) caused a concentration-dependent increase in current that demonstrated strong inward rectification at positive membrane potentials. In cell-attached mode, the unitary amplitude of levcromakalim-induced native and recombinant heteroconcatemeric Kir6.1-Kir6.2 KATPchannels also showed strong inward rectification at positive membrane potentials. Phorbol 12,13-dibutyrate, but not the inactive phorbol ester, 4α-phorbol 12,13-didecanoate, enhanced the activity of native and heteroconcatemeric KATPchannels at −50 mV. The conductance of the native channels at ∼43 pS was consistent with that of heteroconcatemeric channels with a pore-forming subunit composition of (Kir6.1)3-(Kir6.2). RT-PCR analysis revealed the expression of Kir6.1 and Kir6.2 transcripts in pig urethral myocytes. Our findings provide the first evidence that the predominant KATPchannel expressed in pig urethral smooth muscle possesses a unique, heteromeric pore structure that differs from the homomeric Kir6.1 channels of vascular myocytes and is responsible for the differences in inward rectification, conductance, and PKC regulation exhibited by the channels in these smooth muscle cell types.
Vasopressin receptor-mediated functional signaling pathway in primary cilia of renal epithelial cells
Authors: Raychowdhury Malay K. , Ramos Arnolt J. , Zhang Peng , McLaughin Margaret , Dai Xiao-Qing , Chen Xing-Zhen , Montalbetti Nicolás , del Rocío Cantero María , Ausiello Dennis A. , Cantiello Horacio F.
Published: October 2008

The primary cilium of renal epithelial cells is a nonmotile sensory organelle, implicated in mechanosensory transduction signals. Recent studies from our laboratory indicate that renal epithelial primary cilia display abundant channel activity; however, the presence and functional role of specific membrane receptors in this organelle are heretofore unknown. Here, we determined a functional signaling pathway associated with the type 2 vasopressin receptor (V2R) in primary cilia of renal epithelial cells. Besides their normal localization on basolateral membrane, V2R was expressed in primary cilia of LLC-PK1renal epithelial cells. The presence of V2R in primary cilia was determined by spontaneous fluorescence of a V2R- gfp chimera and confirmed by immunocytochemical analysis of wild-type LLC-PK1cells stained with anti-V2R antibodies and in LLC-PK1cells overexpressing the V2R-Flag, with anti-Flag antibody. Ciliary V2R colocalized with adenylyl cyclase (AC) type V/VI in all cell types tested. Functional coupling of the receptors with AC was confirmed by measurement of cAMP production in isolated cilia and by testing AVP-induced cation-selective channel activity either in reconstituted lipid bilayers or subjected to membrane-attached patch clamping. Addition of either 10 μM AVP ( trans) or forskolin ( cis) in the presence but not the absence of ATP (1 mM, cis) stimulated cation-selective channel activity in ciliary membranes. This channel activity was reduced by addition of the PKA inhibitor PKI. The data provide the first demonstration for the presence of V2R in primary cilia of renal epithelial cells, and a functional cAMP-signaling pathway, which targets ciliary channel function and may help control the sensory function of the primary cilium.
Angiotensin II-induced contraction is attenuated by nitric oxide in afferent arterioles from the nonclipped kidney in 2K1C
Authors: Helle Frank , Hultström Michael , Skogstrand Trude , Palm Fredrik , Iversen Bjarne M.
Published: October 2008

Two-kidney, one-clip (2K1C) is a model of renovascular hypertension where we previously found an exaggerated intracellular calcium (Ca[Formula: see text]) response to ANG II in isolated afferent arterioles (AAs) from the clipped kidney (Helle F, Vagnes OB, Iversen BM. Am J Physiol Renal Physiol 291: F140–F147, 2006). To test whether nitric oxide (NO) ameliorates the exaggerated ANG II response in 2K1C, we studied ANG II (10−7 mol/l)-induced calcium signaling and contractility with or without the NO synthase (NOS) inhibitor NG-nitro-l-arginine methyl ester (l-NAME). In AAs from the nonclipped kidney, l-NAME increased the ANG II-induced Ca[Formula: see text] response from 0.28 ± 0.05 to 0.55 ± 0.09 (fura 2, 340 nm/380 nm ratio) and increased contraction from 80 ± 6 to 60 ± 6% of baseline ( P < 0.05). In vessels from sham and clipped kidneys, l-NAME had no effect. In diaminofluorescein-FM diacetate-loaded AAs from the nonclipped kidney, ANG II increased NO-derived fluorescence to 145 ± 34% of baseline ( P < 0.05 vs. sham), but not in vessels from the sham or clipped kidney. Endothelial NOS (eNOS) mRNA and ser-1177 phosphorylation were unchanged in both kidneys from 2K1C, while eNOS protein was reduced in the clipped kidney compared with sham. Cationic amino acid transferase-1 and 2 mRNAs were increased in 2K1C, indicating increased availability of l-arginine for NO synthesis, but counteracted by decreased scavenging of the eNOS inhibitor asymmetric dimethylarginine by dimethylarginine dimethylaminohydrolase 2. In conclusion, the Ca[Formula: see text] and contractile responses to ANG II are blunted by NO release in the nonclipped kidney. This may protect the nonclipped kidney from the hypertension and elevated ANG II levels in 2K1C.
Evaluation of two methods for continuous cardiac output assessment during exercise in chronic heart failure patients
Authors: Kemps Hareld M. C. , Thijssen Eric J. M. , Schep Goof , Sleutjes Boudewijn T. H. M. , De Vries Wouter R. , Hoogeveen Adwin R. , Wijn Pieter F. F. , Doevendans Pieter A. F. M.
Published: October 2008

The purpose of this study was to evaluate the accuracy of two techniques for the continuous assessment of cardiac output in patients with chronic heart failure (CHF): a radial artery pulse contour analysis method that uses an indicator dilution method for calibration (LiDCO) and an impedance cardiography technique (Physioflow), using the Fick method as a reference. Ten male CHF patients (New York Heart Association class II–III) were included. At rest, cardiac output values obtained by LiDCO and Physioflow were compared with those of the direct Fick method. During exercise, the continuous Fick method was used as a reference. Exercise, performed on a cycle ergometer in upright position, consisted of two constant-load tests at 30% and 80% of the ventilatory threshold and a symptom-limited maximal test. Both at rest and during exercise LiDCO showed good agreement with reference values [bias ± limits of agreement (LOA), −1% ± 28% and 2% ± 28%, respectively]. In contrast, Physioflow overestimated reference values both at rest and during exercise (bias ± LOA, 48% ± 60% and 48% ± 52%, respectively). Exercise-related within-patient changes of cardiac output, expressed as a percent change, showed for both techniques clinically acceptable agreement with reference values (bias ± LOA: 2% ± 26% for LiDCO, and −2% ± 36% for Physioflow, respectively). In conclusion, although the limits of agreement with the Fick method are pretty broad, LiDCO provides accurate measurements of cardiac output during rest and exercise in CHF patients. Although Physioflow overestimates cardiac output, this method may still be useful to estimate relative changes during exercise.
Modulation of Transient and Persistent Inward Currents by Activation of Protein Kinase C in Spinal Ventral Neurons of the Neonatal Rat
Authors: Dai Yue , Jordan Larry M. , Fedirchuk Brent
Published: October 2008

Neuronal excitability can be regulated through modulation of voltage threshold ( Vth). Previous studies suggested that this modulation could be mediated by modulation of transient sodium currents ( IT) and/or persistent inward current (PIC). Modulation of ITand PIC through activation of protein kinase C (PKC) has previously been described as a mechanism controlling neuronal excitability. We investigated modulation of ITand PIC by PKC in neonatal rat spinal ventral neurons. In whole cell voltage clamp, activation of PKC by application of 1-oleoyl-2-acetyl-sn-glycerol (OAG, 10–30 μM) resulted in 1) a reduction of ITamplitude by 33% accompanied an increase in half-width and a decrease in the maximal rise and decay rates of the IT; 2) a reduction of PIC amplitude by 49%, with a depolarization of PIC onset by 4.5 mV. Activation of PKC caused varied effects on Vthfor eliciting IT, with an unchanged Vthor depolarized Vthbeing the most common effects. In current-clamp recordings, PKC activation produced a small but significant depolarization (2.0 mV) of Vthfor action potential generation with an increase in half-width and a decrease in amplitude and the maximal rise and decay rates of action potentials. Inclusion of PKCI19–36(10–30 μM), a PKC inhibitor, in the recording pipette could block the OAG effects on ITand PIC. The ability of serotonin to hyperpolarize Vthwas not altered by PKC activation or inhibition. This study demonstrates that activation of PKC decreases the excitability of spinal ventral neurons and that Vthcan be modulated by multiple mechanisms.
Coupling Between Horizontal and Vertical Components of Saccadic Eye Movements During Constant Amplitude and Direction Gaze Shifts in the Rhesus Monkey
Authors: Freedman Edward G.
Published: October 2008

When the head is free to move, changes in the direction of the line of sight (gaze shifts) can be accomplished using coordinated movements of the eyes and head. During repeated gaze shifts between the same two targets, the amplitudes of the saccadic eye movements and movements of the head vary inversely as a function of the starting positions of the eyes in the orbits. In addition, as head-movement amplitudes and velocities increase, saccade velocities decline. Taken together these observations lead to a reversal in the expected correlation between saccade duration and amplitude: small-amplitude saccades associated with large head movements can have longer durations than larger-amplitude saccades associated with small head movements. The data in this report indicate that this reversal occurs during gaze shifts along the horizontal meridian and also when considering the horizontal component of oblique saccades made when the eyes begin deviated only along the horizontal meridian. Under these conditions, it is possible to determine whether the variability in the duration of the constant amplitude vertical component of oblique saccades is accounted for better by increases in horizontal saccade amplitude or increases in horizontal saccade duration. Results show that vertical saccade duration can be inversely related to horizontal saccade amplitude (or unrelated to it) but that horizontal saccade duration is an excellent predictor of vertical saccade duration. Modifications to existing hypotheses of gaze control are assessed based on these new observations and a mechanism is proposed that can account for these data.
The Role of Protein Kinase A in the Ethanol-Induced Increase in Spontaneous GABA Release Onto Cerebellar Purkinje Neurons
Authors: Kelm M. Katherine , Criswell Hugh E. , Breese George R.
Published: October 2008

Ethanol increases miniature inhibitory postsynaptic current frequency and decreases the paired-pulse ratio, which suggests that ethanol increases both spontaneous and evoked GABA release, respectively. We have shown previously that ethanol increases GABA release at the rat interneuron–Purkinje cell synapse and that this ethanol effect involves calcium release from internal stores; however, further exploration of the mechanism responsible for ethanol-enhanced GABA release was needed. We found that a cannabinoid receptor 1 (CB1) agonist, WIN-55212, and a GABABreceptor agonist, baclofen, decreased baseline spontaneous GABA release and prevented ethanol from increasing spontaneous GABA release. The CB1 receptor and GABABreceptor are Gα i–linked G protein–coupled receptors with common downstream messengers that include adenylate cyclase and protein kinase A (PKA). Adenylate cyclase and PKA antagonists blocked ethanol from increasing spontaneous GABA release, whereas a PKA antagonist limited to the postsynaptic neuron did not block ethanol from increasing spontaneous GABA release. These results suggest that presynaptic PKA plays an essential role in ethanol-enhanced spontaneous GABA release. Similar to ethanol, we found that the mechanism of the cannabinoid-mediated decrease in spontaneous GABA release involves internal calcium stores and PKA. A PKA antagonist decreased baseline spontaneous GABA release. This effect was reduced after incubating the slice with a calcium chelator, BAPTA-AM, but was unaffected when BAPTA was limited to the postsynaptic neuron. This suggests that the PKA antagonist is acting through a presynaptic, calcium-dependent mechanism to decrease spontaneous GABA release. Overall, these results suggest that PKA activation is necessary for ethanol to increase spontaneous GABA release.
Navigational Experience Affects Hippocampus Size in Homing Pigeons
Authors: Cnotka Julia , Möhle Martin , Rehkämper Gerd
Published: October 2008

Homing (racing) pigeons (Columba livia f.d.) are well-known for their homing abilities, which are thought to be based on a genetic predisposition, multimodal learning and spatial cognition. On average, the hippocampus, a forebrain structure that processes spatial information, is larger in homing pigeons compared to other non-homing pigeon breeds or their wild ancestor, the rock dove. Here we show that this characteristic hippocampus volume is dependent on flying and navigational experience. Twenty homing pigeons originating from the same breeding stock were raised in the same loft under identical constraints. After fledging, 10 of them were allowed to fly around the loft, gain navigational experience and participate successfully in races. The other 10 stayed permanently in the loft and thus did not share the navigational skill experienced by the first group. After reaching sexual maturity, individuals of both groups were sacrificed and morphometric analyses were carried out to measure the volumes of total brain, telencephalon, hippocampus and 12 other brain structures. Individuals with experience in flying and navigation had an 11.2% larger hippocampus relative to the telencephalon compared to non-experienced individuals (p = 0.028). This effect is not seen in any of the other measured brain subdivisions. Given that plasticity in hippocampal volume has a genetic component, our results confirm that there is also an experience component, and that has certain implications for navigational ability. Evidently, experience is a precondition to full hippocampal development.
Quantitative Evaluation of Carotid Plaque Echogenicity by Integrated Backscatter Analysis: Correlation with Symptomatic History and Histologic Findings
Authors: Nagano Keiko , Yamagami Hiroshi , Tsukamoto Yoshitane , Nagatsuka Kazuyuki , Yasaka Masahiro , Nagata Izumi , Hori Masatsugu , Kitagawa Kazuo , Naritomi Hiroaki
Published: October 2008

Background and Purpose: Echogenicity of carotid plaque well reflects the risk of ischemic stroke and may be predictive of the histologic content of the plaque. However, objective evaluation of plaque echogenicity has been hampered by a lack of established quantitative measures. This study examined the relation between echogenicity assessed by integrated backscatter (IBS) analysis and (1) symptomatic history and (2) histologic features of carotid plaques. Methods: We used acoustic densitometry to quantify by IBS analysis the echogenicity of 31 carotid plaques of 26 patients undergoing carotid endarterectomy or stenting. IBS was subsequently compared with histologic findings of the respective tissue in 10 patients who underwent endarterectomy. The IBS value was calibrated with 2 reference structures (vessel lumen and adventitia) as the IBS index. Results: The IBS index of symptomatic plaques was lower than that of asymptomatic plaques (23.1 ± 12.5 vs. 36.5 ± 18.2, p < 0.05). The IBS index in fatty/necrotic atheromatous sites (n = 20, 16.6 ± 10.7) was lower than that in fibrous (n = 26, 42.4 ± 13.6, p < 0.01) or calcified (n = 11, 87.7 ± 17.4, p < 0.01) sites and the same as that in intraplaque hemorrhagic sites (n = 50, 23.6 ± 16.9). Conclusions: Carotid plaque echogenicity, as quantitatively assessed by IBS analysis, correlates well with the presence or absence of prior symptoms and histologic contents of the plaques. IBS analysis may aid in the assessment of carotid plaque-related risk of stroke.
Emerging Targets of the GnRH Receptor: Novel Interactions with Wnt Signalling Mediators
Authors: Gardner Samantha , Pawson Adam J.
Published: October 2008

The diversity of signalling pathways that gonadotropin-releasing hormone (GnRH) receptors can target has been extended markedly in recent years, ranging from classical heterotrimeric G-protein-coupled second-messenger mobilisation to MAPK cascade activation and epidermal growth factor receptor transactivation. More recently, the targeting of non-classical signalling pathways has been demonstrated, including the activation of monomeric G-proteins and integrin/focal adhesion complexes to mediate cytoskeletal remodelling, androgen receptor nuclear translocation, and luteinising hormone beta-subunit gene transcription. These have been further extended to include c-Src-mediated activation of diacylglycerol kinase, and a novel mechanism of cross-talk to prostaglandin receptor signalling. Here, we review these recent advances and highlight several emerging dimensions in GnRH receptor-mediated signal transduction. These include the targeting of mediators of classical insulin signalling, and Wnt signalling pathways. Collectively, this diverse nature of GnRH receptor signalling is suggestive of an important role for GnRH in a variety of normal physiological and pathophysiological processes in the reproductive system.
Treatment of Folliculitis with Monochromatic Excimer Light (308 nm)
Authors: Nisticò Steven P. , Saraceno Rosita , Carboni Isabella , Chimenti Sergio
Published: October 2008

Background/Aims: 308-nm excimer light has been reported to be safe and effective in the treatment of chronic skin diseases. The aim of the study wasto prove the efficacy of 308-nm monochromatic excimer light in the treatment of recalcitrant and antibiotic-resistant folliculitis. Methods: Eight patients affected with folliculitis were enrolled and treated twice weekly with the 308-nm excimer light. The follow-up was 12 weeks from the end of the treatment. Results: A mean number of 13 sessions (range 10–20) was performed with increasing dosage according to the patient’s phototype and response. Remission, in terms of number and infiltration of papulopustular elements, was achieved in all patients after 4–16 therapeutic sessions. At the end of the follow-up period, recurrence of folliculitis was observed in 2 patients. Conclusions: These results suggest that the 308-nm excimer light is a valid therapeutic option for the treatment of resistant forms of folliculitis especially in difficult-to-treat areas.
Patch Tests in Children with Suspected Allergic Contact Dermatitis: A Prospective Study and Review of the Literature
Authors: de Waard-van der Spek Flora B. , Oranje Arnold P.
Published: October 2008

Aims: The results of patch testing in children visiting our out-patient clinic with suspected allergic contact dermatitis (ACD) were prospectively investigated and compared with those reported in the literature. A review of the literature on patch testing and ACD in children is provided. Methods: Children were patch tested using the TRUE® test, supplemented with tixocortol-17-pivalate, budesonide and 3 commonly used emollients. Supplementary patch tests were undertaken on indication. Results: Seventy-nine children (31 boys and 48 girls) were patch tested. Of the patients tested, 40 (51%) had 1 or more positive allergic patch test reactions. Twenty-two (55%) of these 40 children suffered from atopic dermatitis, 9 (23%) from hand or foot dermatitis, and 9 (23%) from other skin ailments. Nickel was the most common contact allergen, but many other common and less common allergens were noted to give positive patch tests in patients. Conclusion: Sensitization to contact allergens may begin in infancy and continue to be more common in toddlers and young children. In recalcitrant atopic dermatitis, especially at the age of 5 years and over, patch tests are indicated. Good information on preventing the development of ACD in children is useful for caregivers.
Increased Plasma Levels of Asymmetric Dimethylarginine and Soluble CD40 Ligand in Patients with Sleep Apnea
Authors: Barceló Antonia , de la Peña Mónica , Ayllón Olga , Vega-Agapito M. Victoria , Piérola Javier , Pérez Gerardo , González Constancio , Alonso Alberto , Agustí Alvar G.N.
Published: October 2008

Background: Cardiovascular (CV) diseases are a leading cause of mortality and they are frequent in patients with the obstructive sleep apnea syndrome (OSAS). Objectives: In this study we investigated if OSAS influences CV function independently of other CV risk factors frequently present in these patients (e.g. obesity, high blood pressure). Methods: We compared plasma markers of endothelial dysfunction, asymmetric dimethylarginine (ADMA) and endothelin-1 (ET-1), and atherosclerosis progression (soluble fraction of the CD40 ligand, sCD40L) in OSAS patients with (n = 23) and without (n = 18) concurrent CV risk factors, as well as in healthy subjects (n = 23). Results: Plasma ADMA (p < 0.01) and sCD40L (p < 0.05) were abnormally increased in patients with OSAS versus healthy controls, but they were not influenced by the presence or absence of CV risk factors in OSAS. ET-1 levels were not different between the three groups of subjects studied. Conclusions: OSAS is associated with endothelial injury and atherosclerosis progression independently of other CV risk factors.
Positively Regulated Glycerol/G3P-Dependent Bacillus subtilis Gene Expression System Based on Anti-Termination
Authors: Lewin Anna , Su Xiao-Dong , Hederstedt Lars
Published: October 2008

Plasmid pLALA was constructed for glycerol or glycerol-3-phosphate inducible plasmid-borne gene expression in Bacillus subtilis and closely related Gram-positive bacteria. Gene expression using pLALA is based on anti-termination of transcription and involves the B. subtilis GlpP protein that in the presence of glycerol-3-phosphate acts as an anti-terminator protein by binding to the 5′-untranslated region of glpD mRNA. Properties and the usefulness of the system, denoted LALA, were validated by inducible production in B. subtilis strainsof two water-soluble proteins (β-galactosidase and a protein phospho-tyrosine phosphatase), and one integral membrane protein (heme A synthase). Advantages with LALA is that it is based on positive control, does not involve a DNA-binding protein, and that glycerol, a cheap and stable compound, can be used as inducer of gene expression.