bluuebunny/crossref_metadata_2025 huggingface dataset:
STRUCTURAL BASIS OF ANTIFREEZE PROTEIN ACTION
Authors: STROM CHRISTINA S. , LIU XIANG YANG , JIA ZONGCHAO
Published: September 2006

Antifreeze Proteins (AFPs) modify the growth rates and orientations of ice crystal facets through attainment of the best structural match. The insect-type AFPs have ice binding surfaces (IBS) with regularly spaced binding intervals in two directions that engage the primary ice surfaces and reduce their growth rates preferentially. The primary ice surfaces are kinetically stable and have fixed orientations, since they are strongly bonded in two directions. The fish-type AFPs have one-dimensional helical and irregular globular IBSs that are either linearly extended with regular ice binding intervals, or have ice binding sites lacking spacing regularity. They adjust the orientations of the secondary ice surfaces, that have indeterminate face indices since they are strongly bonded in only one direction. The fish-type AFPs stabilize secondary ice surfaces and adjust their orientations by mimicking strong bonding directions, that are not present in the ice structure. The theory agrees with experimental observation and explains hitherto unexplained phenomena. The observed broad variation in prismatic and, more importantly, pyramidal ice crystallites produced in the presence of fish-type AFPs is explained, since these faces are secondary. The observed crystals triggered by most insect-type AFPs are disk shaped, because they consist of primary ice surfaces. The allegedly exceptional ice pyramids triggered by the insect-type TmAFP are the primary ice pyramid with fixed indices, and entirely different from the pyramids of the fish-type AFPs.
MACROMOLECULAR CROWDING IN BIOLOGICAL SYSTEMS: DYNAMIC LIGHT SCATTERING (DLS) TO QUANTIFY THE EXCLUDED VOLUME EFFECT (EVE)
Authors: HARVE KARTHIK S. , RAGHUNATH MICHAEL , LAREU RICKY R. , RAJAGOPALAN RAJ
Published: September 2006

Macromolecules crowd defined spaces, thereby excluding other like-sized molecules from the volume they occupy. These excluded-volume effect(s) (EVE) are well characterized for intracellular and partially for extracellular compartments such as blood plasma. We showed that EVE in fibroblast culture leads to faster enzymatic procollagen conversion and matrix deposition. Apparently, EVE can be applied to emulate in vivo conditions in an in vitro setting. Thus, we attempted to quantitatively capture the crowding potential of various macromolecules using dynamic light scattering under physiological conditions. We found that charged macromolecules like dextran sulfate (negative, 500 kDa) have a hydrodynamic radii of 46.4 ± 0.3 nm i.e. ~4 fold larger than that of neutral macromolecules like Ficoll (neutral, 400 kDa) and thus show greater EVE potential. At biologically effective concentrations viscosity was not increased. Unexpectedly, we observed a dramatic drop of hydrodynamic radii of all macromolecules tested above a threshold concentration. This suggested a hyper-crowding state in which the crowders compacted themselves mutually. We will use this hyper-crowding threshold to determine retrogradely rules that allow to predict the conditions for optimum crowding effects (such as the half-hyper-crowding concentration) in biological systems. We propose Dynamic Light Scattering (DLS) as a potential tool to estimate EVE in biotechnical applications.
ELECTRICAL IMPEDANCE SPECTROSCOPY CHARACTERIZATIONS OF ALKYL-FUNCTIONALIZED SILICON(111)
Authors: WONG ELICIA L. S. , CHILCOTT TERRY C. , JAMES MICHAEL , COSTER HANS G. L.
Published: September 2006

This organic thin-film systems that are based on silicon-carbon covalent bonds have been shown to lead to densely packed alkyl monolayers that have potential bio-passivation or bio-sensing applications. Presented are electrical impedance spectroscopy (EIS) characterisations of a series of alkyl monolayers [ CH 3( CH 2)m CH = CH 2; m = 7, 9, 11, 13, 15] that were covalently linked to Si (111) wafers. The characterizations reveal capacitance, conductance and geometrical properties of the monolayers. The capacitance properties yield estimates of thicknesses for the monolayers that increase proportionally with each additional CH 2 unit and are consistent with the known physical properties of these films such as dielectric constants and chain canting angles. This study illustrates that EIS charcterizations are able to probe immobilized surfaces on silicon with sub-atomic resolution which is so important in the development of practical bio-passivation or bio-sensing applications.
VIBRATIONAL INFRARED LIFETIME OF THE ANESTHETIC NITROUS OXIDE GAS IN SOLUTION
Authors: CHIEFFO LOGAN , AMSDEN JASON J. , SHATTUCK JEFFREY , HONG MI K. , ZIEGLER LAWRENCE , ERRAMILLI SHYAMSUNDER
Published: September 2006

The lifetime of the asymmetric fundamental stretching 2218 cm-1vibration of the anesthetic gas nitrous oxide ( N2O ) dissolved in octanol and olive oil is reported. These solvents are model systems commonly used to assess anesthetic potency. Picosecond time-scale molecular dynamics simulations have suggested that protein dynamics or membrane dynamics play a role in the molecular mechanism of anesthetic action. Ultrafast infrared spectroscopy with 100 fs time resolution is an ideal tool to probe dynamics of anesthetic molecules on such timescales. Pump-probe studies centered at the peak of the vibrational band yield a lifetime of 55 ± 1 ps in olive oil and 52 ± 1 ps in octanol. The similarity of lifetimes suggests that energy relaxation of the anesthetic is determined primarily by the hydrophobic nature of the environment, consistent with models of anesthetic action. The results show that nitrous oxide is a good model system for probing anesthetic-solvent interactions using nonlinear infrared spectroscopy.
Birth-Death Models in Macroevolution
Authors: Nee Sean
Published: September 2006

Birth-death models, and their subsets—the pure birth and pure death models—have a long history of use for informing thinking about macroevolutionary patterns. Here we illustrate with examples the wide range of questions they have been used to address, including estimating and comparing rates of diversification of clades, investigating the “shapes” of clades, and some rather surprising uses such as estimating speciation rates from data that are not resolved below the level of the genus. The raw data for inference can be the fossil record or the molecular phylogeny of a clade, and we explore the similarites and differences in the behavior of the birth-death models when applied to these different forms of data.
Biology of the Bed Bugs (Cimicidae)
Authors: Reinhardt Klaus , Siva-Jothy Michael T.
Published: September 2006

The cimicids, or bed bugs, belong to a highly specialized hematophagous taxon that parasitizes primarily humans, birds, and bats. Their best-known member is the bed bug, Cimex lectularius. This group demonstrates some bizarre but evolutionarily important biology. All members of the family Cimicidae show traumatic insemination and a suite of female adaptations to this male trait. Cimicids therefore constitute an ideal model system for examining the extreme causes and consequences of sexual selection. Our dual goal in re-examining the extensive literature on this group is to identify issues relevant to pest control, such as dispersal ecology and the recent global spread, and to understand the selective forces that have shaped the unique aspects of this insect's biology.
The Use of Push-Pull Strategies in Integrated Pest Management
Authors: Cook Samantha M. , Khan Zeyaur R. , Pickett John A.
Published: September 2006

Push-pull strategies involve the behavioral manipulation of insect pests and their natural enemies via the integration of stimuli that act to make the protected resource unattractive or unsuitable to the pests (push) while luring them toward an attractive source (pull) from where the pests are subsequently removed. The push and pull components are generally nontoxic. Therefore, the strategies are usually integrated with methods for population reduction, preferably biological control. Push-pull strategies maximize efficacy of behavior-manipulating stimuli through the additive and synergistic effects of integrating their use. By orchestrating a predictable distribution of pests, efficiency of population-reducing components can also be increased. The strategy is a useful tool for integrated pest management programs reducing pesticide input. We describe the principles of the strategy, list the potential components, and present case studies reviewing work on the development and use of push-pull strategies in each of the major areas of pest control.
Role of CCN2/CTGF in the proliferation of Mastomys enterochromaffin-like cells and gastric carcinoid development
Authors: Kidd M. , Modlin I. M. , Eick G. N. , Camp R. L. , Mane S. M.
Published: September 2006

Mastomys enterochromaffin-like (ECL) cell proliferation is initially gastrin driven, but once neoplasia develops, cells become gastrin autonomous. We hypothesized that CCN2 (CTGF), a mitogenic growth factor, may regulate ECL cell proliferation. A Mastomys GeneChip database was examined (dCHIP) to identify CCN2 expression levels. CCN2 in normal and tumor ECL cell preparations obtained using FACS (100 nM acridine orange) was examined by real-time PCR. CCN2 protein was identified in mucosal and ECL cell preparations by immunohistochemistry. Short-term cultured cells were stimulated with either CCN2 or CCN2 + EGF, and proliferation was measured (MTT assay). The ERK1/2 inhibitor PD-98059 (0.1–100 μM) was assessed in terms of CCN2 (1 ng/ml)-mediated proliferation and ERK1/2 phosphorylation. CCN2 transcript and protein was then examined in clinical gastric carcinoids. The ccn2 transcript was upregulated in tumor samples compared with the normal mucosa (+2.36-fold, P < 0.01). PCR demonstrated that ccn2 was not expressed in FACS-prepared (>98% pure) normal ECL cells but was elevated in tumor ECL cell fractions (41.3 ± 10.7-fold). Immunostaining of the Mastomys gastric mucosa and FACS preparations confirmed that CCN2 protein was present in ECL tumors but not in normal ECL cells. Neither CCN2 nor CCN2 + EGF stimulated normal ECL cell proliferation. CCN2 stimulated tumor proliferation (EC50 ∼0.01 ng/ml); EGF significantly augmented ( P < 0.01) CCN2-induced tumor cell proliferation (EC50 = 20 pg/ml). PD-98059 inhibited CCN2-induced proliferation (−12 ± 3%, P < 0.05) and ERK1/2 phosphorylation (−34 ± 5%, P < 0.05) in tumor cells. In clinical samples, both CCN2 transcript and protein were elevated in gastrin-autonomous carcinoids ( P < 0.02) compared with the normal mucosa. In conclusion, CCN2 may be a proliferative regulator of Mastomys ECL neoplastic proliferation once these cells become autonomous of gastrin regulation. Identification of CCN2 in gastric carcinoid tissue may be useful both as an indicator of ECL cell transformation and may define gastrin autonomy, a criteria of gastric carcinoid malignancy.
Baroreflex responses to electrical stimulation of aortic depressor nerve in conscious SHR
Authors: Salgado Helio C. , Barale Álvaro R. , Castania Jaci A. , Machado Benedito H. , Chapleau Mark W. , Fazan Rubens
Published: September 2006

Baroreflex responses to changes in arterial pressure are impaired in spontaneously hypertensive rats (SHR). Mean arterial pressure (MAP), heart rate (HR), and regional vascular resistances were measured before and during electrical stimulation (5–90 Hz) of the left aortic depressor nerve (ADN) in conscious SHR and normotensive control rats (NCR). The protocol was repeated after β-adrenergic-receptor blockade with atenolol. SHR exhibited higher basal MAP (150 ± 5 vs. 103 ± 2 mmHg) and HR (393 ± 9 vs. 360 ± 5 beats/min). The frequency-dependent hypotensive response to ADN stimulation was preserved or enhanced in SHR. The greater absolute fall in MAP at higher frequencies (−68 ± 5 vs. −38 ± 3 mmHg at 90-Hz stimulation) in SHR was associated with a preferential decrease in hindquarter (−43 ± 5%) vs. mesenteric (−27 ± 3%) resistance. In contrast, ADN stimulation decreased hindquarter and mesenteric resistances equivalently in NCR (−33 ± 7% and −30 ± 7%). Reflex bradycardia was also preserved in SHR, although its mechanism differed. Atenolol attenuated the bradycardia in SHR (−88 ± 14 vs. −129 ± 18 beats/min at 90-Hz stimulation) but did not alter the bradycardia in NCR (−116 ± 16 vs. −133 ± 13 beats/min). The residual bradycardia under atenolol (parasympathetic component) was reduced in SHR. MAP and HR responses to ADN stimulation were also preserved or enhanced in SHR vs. NCR after deafferentation of carotid sinuses and contralateral right ADN. The results demonstrate distinct differences in central baroreflex control in conscious SHR vs. NCR. Inhibition of cardiac sympathetic tone maintains reflex bradycardia during ADN stimulation in SHR despite impaired parasympathetic activation, and depressor responses to ADN stimulation are equivalent or even greater in SHR due to augmented hindquarter vasodilation.
Does coronary vasodilation after adenosine override endothelin-1-induced coronary vasoconstriction?
Authors: Loghin Catalin , Sdringola Stefano , Gould K. Lance
Published: September 2006

Endothelin-1 is a powerful coronary vasoconstrictor that is overexpressed in coronary artery disease. Adenosine is a powerful coronary vasodilator used for myocardial perfusion imaging to identify flow-limiting coronary artery stenosis. Therefore, in an animal model we tested the hypothesis that intracoronary endothelin-1 may cause myocardial perfusion abnormalities by positron emission tomography (PET) at resting conditions that may persist or only partially improve after intravenous adenosine stress in the absence of myocardial scar and flow-limiting stenosis. Fourteen dogs underwent serial PET perfusion imaging with rubidium-82 before and after subselective intracoronary infusion of endothelin-1, followed by intravenous and then intracoronary adenosine. Small physiological doses of endothelin-1 infused into the mid-left circumflex coronary artery caused quantitatively significant resting perfusion abnormalities that normalized after intracoronary adenosine but not consistently after intravenous adenosine used for diagnostic imaging. After effects of adenosine abated, resting perfusion defects returned, lasting up to 5 h in some animals. Cumulative doses of endothelin-1 caused perfusion defects that did not normalize after intravenous adenosine. In an animal model without myocardial scar or flow-limiting stenosis, intracoronary endothelin-1 causes visually apparent, quantitatively significant, long-lasting myocardial perfusion defects at resting conditions that may persist or only partially improve after intravenous adenosine used for diagnostic imaging. These results may potentially explain resting perfusion abnormalities or heterogeneity by clinical PET that may persist or only partially improve after adenosine stress perfusion imaging in the absence of myocardial scar and flow-limiting stenosis.
Visualization in zebrafish larvae of Na+uptake in mitochondria-rich cells whose differentiation is dependent onfoxi3a
Authors: Esaki Masahiro , Hoshijima Kazuyuki , Kobayashi Sayako , Fukuda Hidekazu , Kawakami Koichi , Hirose Shigehisa
Published: September 2006

Uptake of Na+from the environment is an indispensable strategy for the survival of freshwater fish, as they easily lose Na+from the plasma to a diluted environment. Nevertheless, the location of and molecules involved in Na+uptake remain poorly understood. In this study, we utilized Sodium Green, a Na+-dependent fluorescent reagent, to provide direct evidence that Na+absorption takes place in a subset of the mitochondria-rich (MR) cells on the yolk sac surface of zebrafish larvae. Combined with immunohistochemistry, we revealed that the Na+-absorbing MR cells were exceptionally rich in vacuolar-type H+-ATPase (H+-ATPase) but moderately rich in Na+-K+-ATPase. We also addressed the function of foxi3a, a transcription factor that is specifically expressed in the H+-ATPase-rich MR cells. When foxi3a was depleted from zebrafish embryos by antisense morpholino oligonucleotide injection, differentiation of the MR cells was completely blocked and Na+influx was severely reduced, indicating that MR cells are the primary sites for Na+absorption. Additionally, foxi3a expression is initiated at the gastrula stage in the presumptive ectoderm; thus, we propose that foxi3a is a key gene in the control of MR cell differentiation. We also utilized a set of ion transport inhibitors to assess the molecules involved in the process and discuss the observations.
Sex-dependent differences in the regulation of myocardial protein synthesis following long-term ethanol consumption
Authors: Vary Thomas C. , Kimball Scot R. , Sumner Andrew
Published: September 2006

Chronic heavy alcohol consumption alters cardiac structure and function. Controversies remain as to whether hearts from females respond to the chronic ethanol intake in a manner analogous to males. In particular, sex differences in the myocardial response to chronic alcohol consumption remain unresolved at the molecular level. The purpose of the present set of experiments was to determine whether alterations in cardiac structure and protein metabolism show sexual dimorphism following chronic alcohol consumption for 26 wk. In control animals, hearts from female rats showed lowered heart weights and had thinner ventricular walls compared with males. The smaller heart size was associated with a lower protein content that occurred in part from a reduced rate of protein synthesis. Chronic alcohol consumption in males, but not in females, caused a thinning of the ventricular wall and intraventricular septum, as assessed by echocardiography, correlating with the loss of heart mass. The alterations in cardiac size occurred, in part, through a lowering of the protein content secondary to a diminished rate of protein synthesis. The decreased rate of protein synthesis appeared related to a reduced assembly of active eukaryotic initiation factor (eIF)4G·eIF4E complex secondary to both a diminished phosphorylation of eIF4G and increased formation of inactive 4Ebinding protein (4EBP1)·eIF4E complex. The latter effects occurred as a result of decreased phosphorylation of 4EBP1. None of these ethanol-induced alterations in hearts from males were observed in hearts from females. These data suggest that chronic alcohol-induced impairments in myocardial protein synthesis results, in part, from marked decreases in eIF4E·eIF4G complex formation in males. The failure of female rats consuming ethanol to show structural changes appears related to the inability of ethanol to affect the regulation protein synthesis to the same extent as their male counterparts.
Differential expression of neuronal ACE2 in transgenic mice with overexpression of the brain renin-angiotensin system
Authors: Doobay Marc F. , Talman Lauren S. , Obr Teresa D. , Tian Xin , Davisson Robin L. , Lazartigues Eric
Published: September 2006

Angiotensin-converting enzyme 2 (ACE2) is a newly discovered carboxy-peptidase responsible for the formation of vasodilatory peptides such as angiotensin-(1–7). We hypothesized that ACE2 is part of the brain renin-angiotensin system, and its expression is regulated by the other elements of this system. ACE2 immunostaining was performed in transgenic mouse brain sections from neuron-specific enolase-AT1A(overexpressing AT1Areceptors), R+A+(overexpressing angiotensinogen and renin), and control (nontransgenic littermates) mice. Results show that ACE2 staining is widely distributed throughout the brain. Using cell-type-specific antibodies, we observed that ACE2 staining is present in the cytoplasm of neuronal cell bodies but not in glial cells. In the subfornical organ, an area lacking the blood-brain barrier and sensitive to blood-borne angiotensin II, ACE2 was significantly increased in transgenic mice. Interestingly, ACE2 mRNA and protein expression were inversely correlated in the nucleus of tractus solitarius/dorsal motor nucleus of the vagus and the ventrolateral medulla, when comparing transgenic to nontransgenic mice. These results suggest that ACE2 is localized to the cytoplasm of neuronal cells in the brain and that ACE2 levels appear highly regulated by other components of the renin-angiotensin system, confirming its involvement in this system. Moreover, ACE2 expression in brain structures involved in the control of cardiovascular function suggests that the carboxypeptidase may have a role in the central regulation of blood pressure and diseases involving the autonomic nervous system, such as hypertension.
Effect of aging on the cardiovascular regulatory systems in healthy women
Authors: Lavi Shahar , Nevo Ori , Thaler Israel , Rosenfeld Rimma , Dayan Lior , Hirshoren Nir , Gepstein Lior , Jacob Giris
Published: September 2006

Aging, independently from the hormonal status, is a major risk factor for cardiovascular morbidity in healthy women. Therefore, we studied the effect of healthy aging on the cardiovascular homeostatic mechanisms in premenopausal and postmenopausal women with similar estrogen levels. Twelve healthy postmenopausal women, confirmed by follicular-stimulating hormone (FSH) and luteal hormone (LH) levels, were compared with 14 normally menstruating women during the early follicular phase (young-EF), to avoid as much as possible the effects of estrogen. Systolic BP was 108 ± 1.5 vs. 123 ± 2.5 ( P < 0.001), supine norepinephrine was 260 ± 30 vs. 216 ± 45 and upright 640 ± 100 vs. 395 ± 50 pg/ml ( P = 0.05) in young-EF vs. postmenopausal, respectively. Plasma renin activity and aldosterone remained unchanged. Vagal cardiac tone indices decreased significantly with aging (young-EF vs. postmenopausal): high-frequency (HF) band, root mean square successive differences (rMSSD) and proportion of R-R intervals >50 ms (PNN50%) were 620 ± 140 vs. 270 ± 70 ( P = 0.04), 53 ± 7 vs. 30 ± 3 ( P = 0.02), and 23 ± 5 vs. 10 ± 3 ( P = 0.04), respectively. LF to HF ratio was 0.85 ± 0.17 in young-EF and became 1.5 ± 0.22 in postmenopausal ( P = 0.03). Both arms of the baroreflex, +BRS (29 ± 5 vs. 13.5 ± 2.5, P = 0.01) and −BRS (26 ± 4 vs. 15 ± 1.5, P = 0.02) decreased with aging. Cardiovascular α1-adrenoreceptor responsiveness significantly increased and β-decreased in postmenopausal compared with young EF ( P < 0.001, both). The corrected QT intervals (QTc) were similar, whereas corrected JT intervals (JTc) and JTc to QTc ratio were prolonged in the postmenopausal group. We conclude that in young women, parasympathetic control is the main regulator of the cardiovascular system and in postmenopausal women, sympathetic tone dominates. The transition from parasympathetic to sympathetic control may contribute to the increased cardiovascular morbidity with aging.
Maternal dexamethasone treatment at midgestation reduces nephron number and alters renal gene expression in the fetal spiny mouse
Authors: Dickinson Hayley , Walker David W. , Wintour E. Marelyn , Moritz Karen
Published: September 2006

We investigated the effects of maternal glucocorticoid exposure in the spiny mouse, a precocial species with a relatively long gestation, few offspring, and in which nephrogenesis is complete before birth. We hypothesized that exposure of the fetus to glucocorticoids before the formation of glomeruli would result in adult hypertensive offspring with fewer nephrons. Furthermore, we hypothesized that this nephron deficit would result from changes in expression of genes involved in branching morphogenesis. Osmotic pumps implanted in pregnant spiny mice at midgestation ( day 20) delivered dexamethasone (dex; 125 μg/kg) or saline for 60 h. Females were killed at day 23 of gestation and kidneys were frozen for real-time PCR analysis or allowed to deliver their offspring. At 20 wk of age, blood pressure was measured in the offspring for 1 wk before nephron number was determined using unbiased stereology. Males and females exposed to dex had significantly fewer nephrons (male: saline: 7,870 ± 27, dex: 6,878 ± 173; female: saline: 7,526 ± 62, dex: 5,886 ± 382; P < 0.001) compared with controls. Dex had no effect on basal blood pressure. Fetal kidneys collected at day 23 of gestation from dex-exposed mothers showed increased mRNA expression of BMP4 ( P < 0.05), TGF-β1( P < 0.05), genes known to inhibit branching morphogenesis and gremlin ( P < 0.01), an antagonist of BMP4, compared with saline controls. This study shows for the first time an upregulation of branching morphogenic genes in the fetal kidney in a model of excess maternal glucocorticoids that leads to a nephron deficit in the adult. This study also provides evidence that a reduced nephron number does not necessarily lead to development of hypertension.
Quantitative trait loci for carbohydrate and total energy intake on mouse chromosome 17: congenic strain confirmation and candidate gene analyses (Glo1,Glp1r)
Authors: Kumar K. Ganesh , Poole Angela C. , York Barbara , Volaufova Julia , Zuberi Aamir , Richards Brenda K. Smith
Published: September 2006

Quantitative trait loci (QTL) for carbohydrate ( Mnic1) and total energy ( Kcal2) intake on proximal mouse chromosome 17 were identified previously from a C57BL/6J (B6) X CAST/Ei (CAST) intercross. Here we report that a new congenic strain developed in our laboratory has confirmed this complex locus by recapitulating the original linked phenotypes: B6.CAST-17 homozygous congenic mice consumed more carbohydrate (27%) and total energy (17%) compared with littermate wild-type mice. Positional gene candidates with relevance to carbohydrate metabolism, glyoxalase I ( Glo1) and glucagon-like peptide-1 receptor ( Glp1r), were evaluated. Glo1 expression was upregulated in liver and hypothalamus of congenic mice when compared with B6 mice. Analyses of Glp1r mRNA and protein expression revealed tissue-specific strain differences in pancreas (congenic>B6) and stomach (B6>congenic). These results suggest the possibility of separate mechanisms for enhanced insulin synthesis and gastric accommodation in the presence of high carbohydrate intake and larger food volume, respectively. Sequence analysis of Glp1r found a G insert at nt position 1349, which results in earlier termination of the open reading frame, thus revealing an error in the public sequence. Consequently, the predicted length of GLP-1R is 463 aa compared with 489 aa, as previously reported. Also, we found a polymorphism in Glp1r between parental strains that alters the amino acid sequence. Variation in Glp1r could influence nutrient intake in this model through changes in the regulatory or protein coding regions of the gene. These congenic mice offer a powerful tool for investigating gene interactions in the control of food intake.
IL-1β and LPS induce anorexia by distinct mechanisms differentially dependent on microsomal prostaglandin E synthase-1
Authors: Elander Louise , Engström Linda , Hallbeck Martin , Blomqvist Anders
Published: September 2006

Recent work demonstrated that the febrile response to peripheral immune stimulation with proinflammatory cytokine IL-1β or bacterial wall lipopolysaccharide (LPS) is mediated by induced synthesis of prostaglandin E2by the terminal enzyme microsomal prostaglandin E synthase-1 (mPGES-1). The present study examined whether a similar mechanism might also mediate the anorexia induced by these inflammatory agents. Transgenic mice with a deletion of the Ptges gene, which encodes mPGES-1, and wild-type controls were injected intraperitoneally with IL-1β, LPS, or saline. Mice were free fed, and food intake was continuously monitored with an automated system for 12 h. Body weight was recorded every 24 h for 4 days. The IL-1β induced anorexia in wild-type but not knock-out mice, and so it was almost completely dependent on mPGES-1. In contrast, LPS induced anorexia of the same magnitude in both phenotypes, and hence it was independent of mPGES-1. However, when the mice were prestarved for 22 h, LPS induced anorexia and concomitant body weight loss in the knock-out animals that was attenuated compared with the wild-type controls. These data suggest that IL-1β and LPS induce anorexia by distinct immune-to-brain signaling pathways and that the anorexia induced by LPS is mediated by a mechanism different from the fever induced by LPS. However, nutritional state and/or motivational factors also seem to influence the pathways for immune signaling to the brain. Furthermore, both IL-1β and LPS caused reduced meal size but not meal frequency, suggesting that both agents exerted an anhedonic effect during these experimental conditions.
Residual force enhancement after lengthening is present during submaximal plantar flexion and dorsiflexion actions in humans
Authors: Pinniger Gavin J. , Cresswell Andrew G.
Published: September 2006

Stretch of an activated muscle causes a transient increase in force during the stretch and a sustained, residual force enhancement (RFE) after the stretch. The purpose of this study was to determine whether RFE is present in human muscles under physiologically relevant conditions (i.e., when stretches were applied within the working range of large postural leg muscles and under submaximal voluntary activation). Submaximal voluntary plantar flexion (PFv) and dorsiflexion (DFv) activation was maintained by providing direct visual feedback of the EMG from soleus or tibialis anterior, respectively. RFE was also examined during electrical stimulation of the plantar flexion muscles (PFs). Constant-velocity stretches (15°/s) were applied through a range of motion of 15° using a custom-built ankle torque motor. The muscles remained active throughout the stretch and for at least 10 s after the stretch. In all three activation conditions, the stable joint torque measured 9–10 s after the stretch was greater than the isometric joint torque at the final joint angle. When expressed as a percentage of the isometric torque, RFE values were 7, 13, and 12% for PFv, PFs, DFv, respectively. These findings indicate that RFE is a characteristic of human skeletal muscle and can be observed during submaximal (25%) voluntary activation when stretches are applied on the ascending limb of the force-length curve. Although the underlying mechanisms are unclear, it appears that sarcomere popping and passive force enhancement are insufficient to explain the presence of RFE in these experiments.
Inhibition of mucin secretion with MARCKS-related peptide improves airway obstruction in a mouse model of asthma
Authors: Agrawal A. , Rengarajan S. , Adler K. B. , Ram A. , Ghosh B. , Fahim M. , Dickey B. F.
Published: September 2006

Allergic asthma is associated with airway epithelial cell mucous metaplasia and mucin hypersecretion, but the consequences of mucin hypersecretion on airway function are unclear. Recently, a peptide derived from the myristoylated alanine-rich C kinase substrate protein NH2-terminal sequence (MANS) was shown to inhibit methacholine (MCh)-induced mucin secretion from airway mucous cells by >90%. We studied the effect of intranasal pretreatment with this peptide on specific airway conductance (sGaw) during challenge with MCh in mice with allergen-induced mucous cell metaplasia. sGaw was noninvasively measured in spontaneously breathing restrained mice, using a double-chamber plethysmograph. Pretreatment with MANS peptide, but not a control peptide [random NH2-terminal sequence (RNS)], resulted in partial inhibition of the fall in sGaw induced by 60 mM MCh (mean ± SE; baseline 1.15 ± 0.06; MANS/MCh 0.82 ± 0.05; RNS/MCh 0.55 ± 0.05 cmH2O/s). The protective effect of MANS was also seen in mice challenged with allergen for 3 consecutive days to increase airway hyperresponsiveness, although the degree of protection was less (baseline 1.1 ± 0.08; MANS/MCh, 0.65 ± 0.06; RNS/MCh 0.47 ± 0.03 cmH2O/s). Because routine sGaw measurement in mice includes nasal airways, the effectiveness of MANS was also confirmed in mice breathing through their mouths after nasal occlusion (baseline 0.92 ± 0.05; MANS/MCh 0.83 ± 0.06; RNS/MCh 0.61 ± 0.03 cmH2O/s). In all instances, sGaw in the MANS-pretreated group was ∼35% higher than in RNS-treated controls, and mucous obstruction accounted for ∼50% of the MCh-induced fall in sGaw. In summary, mucin secretion has a significant role in airway obstruction in a mouse model of allergic asthma, and strategies to inhibit mucin secretion merit further investigation.
Impaired flow-mediated dilation with age is not explained by l-arginine bioavailability or endothelial asymmetric dimethylarginine protein expression
Authors: Gates Phillip E. , Boucher Meghan L. , Silver Annemarie E. , Monahan Kevin D. , Seals Douglas R.
Published: September 2006

Aging is associated with a decline in vascular endothelial function, manifesting in part as impaired flow-mediated arterial dilation (FMD), but the underlying mechanisms are uncertain. Impaired FMD may be mediated in part by a decrease in synthesis of nitric oxide by endothelial nitric oxide synthase, and in clinical populations this has been attributed to competitive inhibition of l-arginine binding sites by asymmetric dimethylarginine (ADMA). If this mechanism is involved in the age-associated decline in FMD, increasing l-arginine concentration may swing the competitive balance in favor of l-arginine binding, restoring nitric oxide synthesis, and enhancing FMD in older humans. To test this hypothesis, we measured FMD (brachial ultrasound) in 10 younger (21 ± 1 yr) and 12 older healthy men and women (60 ± 2 yr) following infusion of vehicle or vehicle + l-arginine. Baseline FMD in the older subjects was only ∼60% of that in the younger subjects ( P = 0.002). l-Arginine did not significantly increase FMD in either group despite 23-fold (older) and 19-fold (younger) increases in plasma l-arginine concentrations ( P < 0.0001 vs. control). Protein expression (immunofluorescence) in vascular endothelial cells showed that ADMA and the enzyme isoform that controls its degradation, dimethylarginine dimethylaminohydrolase II, were not different in the younger and older subjects. Endothelium-independent vasodilation (sublingual nitroglycerine) was not different between age groups or conditions. We conclude that acutely increasing plasma concentrations of l-arginine do not significantly improve brachial artery FMD in healthy older subjects and thus does not restore the age-associated loss of FMD. Together with the finding that endothelial cell ADMA protein expression was not increased in older adults, these findings suggest that competitive inhibition of l-arginine binding sites on endothelial nitric oxide synthase by ADMA is not an important mechanism contributing to impaired conduit artery endothelium-dependent dilation with aging in healthy humans.
Sequential Valproic Acid/All-trans Retinoic Acid Treatment Reprograms Differentiation in Refractory and High-Risk Acute Myeloid Leukemia
Authors: Cimino Giuseppe , Lo-Coco Francesco , Fenu Susanna , Travaglini Lorena , Finolezzi Erica , Mancini Marco , Nanni Mauro , Careddu Angela , Fazi Francesco , Padula Fabrizio , Fiorini Roberto , Aloe Spiriti Maria Antonietta , Petti Maria Concetta , Venditti Adriano , Amadori Sergio , Mandelli Franco , Pelicci Pier Giuseppe , Nervi Clara
Published: September 2006

Epigenetic alterations of chromatin due to aberrant histone deacetylase (HDAC) activity and transcriptional silencing of all-trans retinoic acid (ATRA) pathway are events linked to the pathogenesis of acute myeloid leukemia (AML) that can be targeted by specific treatments. A pilot study was carried out in eight refractory or high-risk AML patients not eligible for intensive therapy to assess the biological and therapeutic activities of the HDAC inhibitor valproic acid (VPA) used to remodel chromatin, followed by the addition of ATRA, to activate gene transcription and differentiation in leukemic cells. Hyperacetylation of histones H3 and H4 was detectable at therapeutic VPA serum levels (≥50 μg/mL) in blood mononuclear cells from seven of eight patients. This correlated with myelomonocytic differentiation of leukemic cells as revealed by morphologic, cytochemical, immunophenotypic, and gene expression analyses. Differentiation of the leukemic clone was proven by fluorescence in situ hybridization analysis showing the cytogenetic lesion +8 or 7q− in differentiating cells. Hematologic improvement, according to established criteria for myelodysplastic syndromes, was observed in two cases. Stable disease and disease progression were observed in five and one cases, respectively. In conclusion, VPA-ATRA treatment is well tolerated and induces phenotypic changes of AML blasts through chromatin remodeling. Further studies are needed to evaluate whether VPA-ATRA treatment by reprogramming differentiation of the leukemic clone might improve the response to chemotherapy in leukemia patients. (Cancer Res 2006; 66(17): 8903-11)
Pituitary Adenylate Cyclase-Activating Polypeptide Is a Potent Inhibitor of the Growth of Light Chain-Secreting Human Multiple Myeloma Cells
Authors: Li Min , Cortez Shirley , Nakamachi Tomoya , Batuman Vecihi , Arimura Akira
Published: September 2006

Multiple myeloma represents a malignant proliferation of plasma cells in the bone marrow, which often overproduces immunoglobulin light chains. We have shown previously that pituitary adenylate cyclase-activating polypeptide (PACAP) markedly suppresses the release of proinflammatory cytokines from light chain-stimulated human renal proximal tubule epithelial cells and prevents the resulting tubule cell injury. In this study, we have shown that PACAP suppresses the proliferation of human κ and λ light chain-secreting multiple myeloma–derived cells. The addition of PACAP suppressed light chain-producing myeloma cell–stimulated interleukin 6 (IL-6) secretion by the bone marrow stromal cells (BMSCs). A specific antagonist to either the human PACAP-specific receptor or the vasoactive intestinal peptide receptor attenuated the suppressive effect of PACAP on IL-6 production in the adhesion of human multiple myeloma cells to BMSCs. The secretion of IL-6 by BMSCs was completely inhibited by 10−9 mol/L PACAP, which also attenuated the phosphorylation of both p42/44 and p38 mitogen-activated protein kinases (MAPK) as well as nuclear factor-κB (NF-κB) activation in response to the adhesion of multiple myeloma cells to BMSCs, whereas the inhibition of p42/44 MAPK signaling attenuated PACAP action. The signaling cascades involved in the inhibitory effect of PACAP on IL-6-mediated paracrine stimulation of light chain-secreting myeloma cell growth was mediated through the suppression of p38 MAPK as well as modulation of activation of transcription factor NF-κB. These findings suggest that PACAP may be a new antitumor agent that directly suppresses light chain-secreting myeloma cell growth and indirectly affects tumor cell growth by modifying the bone marrow milieu of the multiple myeloma. (Cancer Res 2006; 66(17): 8796-803)
Interaction of Deleted in Liver Cancer 1 with Tensin2 in Caveolae and Implications in Tumor Suppression
Authors: Yam Judy Wai Ping , Ko Frankie Chi Fat , Chan Chung-Yiu , Jin Dong-Yan , Ng Irene Oi-Lin
Published: September 2006

Deleted in liver cancer 1 (DLC1) is a recently identified tumor suppressor gene frequently underexpressed in hepatocellular carcinoma (HCC). DLC1 encodes a Rho GTPase-activating protein domain that exhibits growth-suppressive activity in HCC cell lines. Our recent finding has revealed that inhibition of Rho-mediated actin stress fiber formation by DLC1 is associated with its growth inhibitory activity. In the present study, we identified tensin2 as the novel binding partner of DLC1. Tensin2 belongs to a new family of focal adhesion proteins that play key roles in cytoskeleton organization and signal transduction. Dysregulation of tensin proteins has previously been implicated in human cancers. Tensin2 is highly expressed in human liver. Introduction of tensin2 into HCC cell lines with low expression of tensin2 caused significant growth inhibition and induction of apoptosis. Tensin2 directly interacted with DLC1 in vitro and in vivo. Both proteins localized to punctate structures in the cytoplasm. Sequence analysis of DLC1 and tensin2 identified caveolin-1 binding motif in both proteins. In vivo immunoprecipitation study confirmed that both proteins indeed interacted with endogenous caveolin-1, which is the major structural component of caveolae. Our findings presented here suggest a new model for the action of DLC1 in hepatocytes, whereby DLC1-tensin2 complex interacts with Rho GTPases in caveolae to effect cytoskeletal reorganization. (Cancer Res 2006; 66(17): 8367-72)
Silencing of p29 Affects DNA Damage Responses with UV Irradiation
Authors: Chu Po-Chen , Yang Yuh-Cheng , Lu Yen-Ta , Chen Hsiang-Ting , Yu Lung-Chih , Chang Mau-Sun
Published: September 2006

Human p29 is a newly identified nuclear protein whose function is largely undetermined. We found that p29 associated with chromatin, interacted with MCM3, and localized with proliferating cell nuclear antigen foci in the S phase. Silencing of p29 using small interfering RNA duplexes reduced DNA synthesis and increased the expression of p107, a member of the RB family, and of cyclin-dependent kinase inhibitor p21, accompanied with a decreased expression of DNA polymerase α. Lethal events consisting of premature chromatin condensation with a reduced Chk1 phosphorylation were observed in p29-depleted cells in response to UV irradiation. Intriguingly, the phosphorylation of ataxia telangectasia-mutated kinases at S1981 was suppressed in p29-depleted HeLa cells with UV irradiation, but not in hydroxyurea- and ionizing radiation-treated cells. Taken together, these results reveal a novel function of p29 in the regulation of DNA replication checkpoint responses. (Cancer Res 2006; 66(17): 8484-91)
Induction of Potent Antitumor Immunity by Intratumoral Injection of Interleukin 23–Transduced Dendritic Cells
Authors: Hu Jinwei , Yuan Xiangpeng , Belladonna Maria L. , Ong John M. , Wachsmann-Hogiu Sebastian , Farkas Daniel L. , Black Keith L. , Yu John S.
Published: September 2006

Dendritic cells (DCs) are potent antigen-presenting cells that play a critical role in priming immune responses to tumor. Interleukin (IL)-23 can act directly on DC to promote immunogenic presentation of tumor peptide in vitro. Here, we evaluated the combination of bone marrow–derived DC and IL-23 on the induction of antitumor immunity in a mouse intracranial glioma model. DCs can be transduced by an adenoviral vector coding single-chain mouse IL-23 to express high levels of bioactive IL-23. Intratumoral implantation of IL-23–expressing DCs produced a protective effect on intracranial tumor–bearing mice. The mice consequently gained systemic immunity against the same tumor rechallenge. The protective effect of IL-23–expressing DCs was comparable with or even better than that of IL-12-expressing DCs. IL-23–transduced DC (DC-IL-23) treatment resulted in robust intratumoral CD8+ and CD4+ T-cell infiltration and induced a specific TH1-type response to the tumor in regional lymph nodes and spleen at levels greater than those of nontransduced DCs. Moreover, splenocytes from animals treated with DC-IL-23 showed heightened levels of specific CTL activity. In vivo lymphocyte depletion experiments showed that the antitumor immunity induced by DC-IL-23 was mainly dependent on CD8+ T cells and that CD4+ T cells and natural killer cells were also involved. In summary, i.t. injection of DC-IL-23 resulted in significant and effective systemic antitumor immunity in intracranial tumor–bearing mice. These findings suggest a new approach to induce potent tumor-specific immunity to intracranial tumors. This approach may have therapeutic potential for treating human glioma. (Cancer Res 2006; 66(17): 8887-96)
Mechanism of Action of Sulforaphane: Inhibition of p38 Mitogen-Activated Protein Kinase Isoforms Contributing to the Induction of Antioxidant Response Element–Mediated Heme Oxygenase-1 in Human Hepatoma HepG2 Cells
Authors: Keum Young-Sam , Yu Siwang , Chang Peter Pil-Jae , Yuan Xiaoling , Kim Jung-Hwan , Xu Changjiang , Han Jiahuai , Agarwal Anupam , Kong Ah-Ng Tony
Published: September 2006

Exposure of sulforaphane to HepG2 cells increased heme oxygenase-1 (HO-1) expression by activating antioxidant response element (ARE) through induction of Nrf2 and suppression of Kelch-like ECH-associated protein 1 (Keap1). Using human HO-1 promoter reporter plasmids and ChIP assay, we have identified that sulforaphane transcriptionally activated the upstream ARE-rich enhancer region, located at −9.0 kb upstream human HO-1 promoter. Induction of HO-1 by sulforaphane was attenuated by overexpression of mutant Nrf2 plasmid in HepG2 cells and totally abolished in Nrf2 knockout mouse embryonic keratinocytes and fibroblasts. Overexpression of individual p38 mitogen-activated protein (MAP) kinase (MAPK) isoforms also suppressed constitutive as well as sulforaphane- or Nrf2-induced ARE-dependent gene expression. Among the upstream kinases, although MKK3 was not involved in suppression of ARE by any of p38 MAPK isoforms, MKK6 selectively suppressed ARE by p38γ or p38δ, but not by p38α or p38β. Importantly, sulforaphane not only activated MAP/extracellular signal-regulated kinase (ERK) kinases 1/2 and ERK1/2, but also strongly suppressed anisomycin-induced activation of p38 MAPK isoforms by blocking phosphorylation of upstream kinases, MKK3/6. Finally, we found that stimulation of p38 MAPK isoforms phosphorylated purified Nrf2 protein and caused an increase in the interaction between Nrf2 and Keap1 in vitro and the suppression of Nrf2 translocation into the nucleus. Collectively, our results indicate that transcriptional activation of Nrf2/ARE is critical in sulforaphane-mediated induction of HO-1, which can be modulated in part by the blockade of p38 MAPK signaling pathway. In addition, our study shows that p38 MAPK can phosphorylate Nrf2 and promotes the association between Nrf2 and Keap1 proteins, thereby potentially inhibiting nuclear translocation of Nrf2. (Cancer Res 2006; 66(17): 8804-13)
Antiangiogenic Effect of TW37, a Small-Molecule Inhibitor of Bcl-2
Authors: Zeitlin Benjamin D. , Joo Esther , Dong Zhihong , Warner Kristy , Wang Guoping , Nikolovska-Coleska Zaneta , Wang Shaomeng , Nör Jacques E.
Published: September 2006

Bcl-2 is an antiapoptotic protein that is up-regulated in several tumor types, and its expression levels have strong correlation to development of resistance to therapy and poor prognosis. We have shown recently that Bcl-2 also functions as a proangiogenic signaling molecule that activates a nuclear factor-κB–mediated pathway resulting in up-regulation of the angiogenic chemokines CXCL1 and CXCL8 by neovascular endothelial cells. Here, we evaluate the antiangiogenic effect of the novel small-molecule inhibitor of Bcl-2 (TW37) developed using a structure-based design strategy. We observed that TW37 has an IC50 of 1.8 μmol/L for endothelial cells but showed no cytotoxic effects for fibroblasts at concentrations up to 50 μmol/L. The mechanism of TW37-induced endothelial cell death was apoptosis, in a process mediated by mitochondrial depolarization and activation of caspase-9 and caspase-3. The effect of TW37 on endothelial cell apoptosis was not prevented by coexposure to the growth factor milieu secreted by tumor cells. Inhibition of the angiogenic potential of endothelial cells (i.e., migration and capillary sprouting assays) and expression of the angiogenic chemokines CXCL1 and CXCL8 were accomplished at subapoptotic TW37 concentrations (0.005-0.05 μmol/L). Notably, administration of TW37 i.v. resulted in a decrease in the density of functional human microvessels in the severe combined immunodeficient mouse model of human angiogenesis. In conclusion, we describe functionally separate proapoptotic and antiangiogenic mechanisms for a small-molecule inhibitor of Bcl-2 and show the potential for Bcl-2 inhibition as a target for antiangiogenic therapy. (Cancer Res 2006; 66(17): 8698-706)