bluuebunny/crossref_metadata_2025 huggingface dataset:
Origin and phenotype of lung side population cells
Authors: Summer Ross , Kotton Darrell N. , Sun Xi , Fitzsimmons Kathleen , Fine Alan
Published: March 2004

Side population (SP) cells, a rare cell type identified by their ability to efflux the vital dye Hoechst 33342, are highly enriched for stem cell activity. Bone marrow (BM) SP cells uniformly express the pan-hematopoietic marker CD45, whereas tissue SP cells are heterogeneous in CD45 expression. In previous studies, we found that CD45 is expressed on 75% of lung SP cells. By performing whole BM transplantations, we determined that CD45-positive and CD45-negative lung SP cells are marrow derived. Transplantation of 200 highly purified BM SP cells indicated that both lung SP cell subtypes are derived from this marrow cell type. Morphologically, CD45-positive lung and BM SP cells possess similar features. They are small, round, and contain scant cytoplasm. CD45-negative lung SP cells are larger and contain abundant granular cytoplasm. Gene expression patterns for hematopoietic transcription factors GATA-1, GATA-2, and PU.1 further differentiated SP marrow and lung subtypes. By immunostaining for α-smooth muscle actin and cytokeratin, we found significant differences in the relative expression patterns of these markers in lung and marrow SP cell subtypes. In summary, these findings demonstrate that lung SP cells are derived from the BM and that CD45-positive and -negative subtypes can be distinguished by morphological differences and gene expression patterns.
Respiratory epithelial cells regulate lung inflammation in response to inhaled endotoxin
Authors: Skerrett Shawn J. , Liggitt H. Denny , Hajjar Adeline M. , Ernst Robert K. , Miller Samuel I. , Wilson Christopher B.
Published: March 2004

To determine the role of respiratory epithelial cells in the inflammatory response to inhaled endotoxin, we selectively inhibited NF-κB activation in the respiratory epithelium using a mutant IκB-α construct that functioned as a dominant negative inhibitor of NF-κB translocation (dnIκB-α). We developed two lines of transgenic mice in which expression of dnIκB-α was targeted to the distal airway epithelium using the human surfactant apoprotein C promoter. Transgene expression was localized to the epithelium of the terminal bronchioles and alveoli. After inhalation of LPS, nuclear translocation of NF-κB was evident in bronchiolar epithelium of nontransgenic but not of transgenic mice. This defect was associated with impaired neutrophilic lung inflammation 4 h after LPS challenge and diminished levels of TNF-α, IL-1β, macrophage inflammatory protein-2, and KC in lung homogenates. Expression of TNF-α within bronchiolar epithelial cells and of VCAM-1 within peribronchiolar endothelial cells was reduced in transgenic animals. Thus targeted inhibition of NF-κB activation in distal airway epithelial cells impaired the inflammatory response to inhaled LPS. These data provide causal evidence that distal airway epithelial cells and the signals they transduce play a physiological role in lung inflammation in vivo.
Inhibition of nitric oxide synthase enhances superoxide activity in canine kidney
Authors: Majid Dewan S. A. , Nishiyama Akira , Jackson Keith E. , Castillo Alexander
Published: March 2004

To evaluate the role of a potential interaction between superoxide anion (O2−) and nitric oxide (NO) in regulating kidney function, we examined the renal responses to intra-arterial infusion of a superoxide dismutase mimetic, tempol (0.5 mg·kg−1·min−1), in anesthetized dogs treated with or without NO synthase inhibitor, Nω-nitro-l-arginine (NLA; 50 μg·kg−1·min−1). In one group of dogs ( n = 10), tempol infusion alone for 30 min before NLA infusion did not cause any significant changes in renal blood flow (RBF; 5.2 ± 0.4 to 5.0 ± 0.4 ml·min−1·g−1), glomerular filtration rate (GFR; 0.79 ± 0.04 to 0.77 ± 0.04 ml·min−1·g−1), urine flow (V; 13.6 ± 2.1 to 13.9 ± 2.5 μl·min−1·g−1), or sodium excretion (UNaV; 2.4 ± 0.3 to 2.2 ± 0.3 μmol·min−1·g−1). Interestingly, when tempol was infused in another group of dogs ( n = 12) pretreated with NLA, it caused increases in V (4.4 ± 0.4 to 9.7 ± 1.4 μl·min−1·g−1) and in UNaV (0.7 ± 0.1 to 1.3 ± 0.2 μmol·min−1·g−1) without affecting RBF or GFR. Although NO inhibition caused usual qualitative responses in both groups of dogs, the antidiuretic (47 ± 5 vs. 26 ± 4%) and antinatriuretic (67 ± 4 vs. 45 ± 11%) responses to NLA were seen much less in dogs pretreated with tempol. NLA infusion alone increased urinary excretion of 8-isoprostane (13.9 ± 2.7 to 22.8 ± 3.6 pg·min−1·g−1; n = 7), which returned to the control levels (11.6 ± 3.4 pg·min−1·g−1) during coadministration of tempol. These data suggest that NO synthase inhibition causes enhancement of endogenous O2−levels and support the hypothesis that NO plays a protective role against the actions of O2−in the kidney.
Longitudinal changes in aerobic power in older men and women
Authors: Stathokostas Liza , Jacob-Johnson Shanthi , Petrella Robert J. , Paterson Donald H.
Published: March 2004

The purpose of this study was to describe the longitudinal (10 yr) decline in aerobic power [maximal O2 uptake (V̇o2 max)] and anaerobic threshold [ventilatory threshold (TV̇e)] of older adults living independently in the community. Ten years after initial testing, 62 subjects (34 men, mean age 73.5 ± 6.4 yr; 28 women, 72.1 ± 5.3 yr) achieved V̇o2 max criteria during treadmill walking tests to the limit of tolerance, with TV̇e determined in a subset of 45. V̇o2 max in men showed a rate of decline of −0.43 ml·kg−1·min−1·yr−1, and the decline in V̇o2 max was consequent to a lowered maximal heart rate with no change in the maximum O2 pulse. The women showed a slower rate of decline of V̇o2 max of −0.19·ml·kg−1·min−1·yr−1 ( P < 0.05), again with a lowered HRmax and unchanged O2 pulse. In this sample, lean body mass was not changed over the 10-yr period. Changes in V̇o2 max were not significantly related to physical activity scores. TV̇e showed a nonsignificant decline in both men and women. Groupings of young-old (65–72 yr at follow-up) vs. old-old (73–90 yr at follow-up) were examined. In men, there were no differences in the rate of V̇o2 max decline. The young-old women showed a significant decline in V̇o2 max, whereas old-old women, initially at a V̇o2 max of 19.4 ± 3.1 ml·kg−1·min−1, showed no loss in V̇o2 max. The longitudinal data, vs. cross-sectional analysis, showed a greater decline for men but similar estimates of the rates of change in women. Thus the 10-yr longitudinal study of the cohort of community-dwelling older adults who remained healthy, ambulatory, and independent showed a 14% decline in V̇o2 max in men, and a smaller decline of 7% in women, with the oldest women showing little change over the 10-yr period.
Differential Temporal Coding of Rhythmically Diverse Acoustic Signals by a Single Interneuron
Authors: Marsat G. , Pollack G. S.
Published: March 2004

The omega neuron 1 (ON1) of the cricket Teleogryllus oceanicus responds to conspecific signals (4.5 kHz) and to the ultrasonic echolocation sounds used by hunting, insectivorous bats. These signals differ in temporal structure as well as in carrier frequency. We show that ON1's temporal coding properties vary with carrier frequency, allowing it to encode both of these behaviorally important signals. Information-transfer functions show that coding of 4.5 kHz is limited to the range of amplitude-modulation components that occur in cricket songs (<32 Hz), whereas coding of 30-kHz stimuli extends to the higher pulse rates that occur in bat sounds (∼100 Hz). Nonlinear coding contributes to the information content of ON1's spike train, particularly for 30-kHz stimuli with high intensities and large modulation depths. Phase locking to sinusoidal amplitude envelopes also extends to higher AM frequencies for ultrasound stimuli. ON1s frequency-specific behavior cannot be ascribed to differences in the shapes of information-transfer functions of low- and high-frequency-tuned receptor neurons, both of which are tuned more broadly to AM frequencies than ON1. Coding properties are nearly unaffected by contralateral deafferentation. ON1's role in auditory processing is to increase binaural contrast through contralateral inhibition. We hypothesize that its frequency-specific temporal coding properties optimize binaural contrast for sounds with both the spectral and temporal features of behaviorally relevant signals.
Tonic Activity of Metabotropic Glutamate Receptors Is Involved in Developmental Modification of Short-Term Plasticity in the Neocortex
Authors: Chen Huan-Xin , Roper Steven N.
Published: March 2004

Maturation of many synapses of the CNS is characterized by a reduction in initial release probability and associated alterations in short-term plasticity (STP). We investigated the role of tonic activity of metabotropic glutamate receptors (mGluRs) in this process in glutamatergic synapses of rat neocortex. Consistent with previous reports, STP of excitatory postsynaptic currents (EPSCs) evoked by five-pulse stimulation was found to switch from depression at postnatal days 13–17 (P13–17) to facilitation at postnatal days 28–42 (P28–42). (2S,2′R,3′R)-2-(2′,3′-dicarboxycyclopropyl)glycine, a specific mGluR2/3 agonist, strongly depressed EPSCs both at the early stage and the late stage of cortical development. This was accompanied by a switch from depression to facilitation of STP at the early stage and an increase in facilitation at the late stage. While application of 2S-2-amino-2-(1S,2S-2-carboxycycloprop-1-yl)-3-(xanth-9-yl) propanoic acid ( LY341495 ), an mGluR antagonist that is most potent at mGluR2/3, had no significant effect at the early stage, it significantly enhanced EPSC amplitude and reduced short-term facilitation at the late stage. Blocking glutamate transporter activity with l- trans-pyrrolidine-2,4-dicarboxylate (tPDC) significantly reduced EPSC amplitude and short-term depression in the younger group but had no effect in the older specimens. The effect of tPDC was blocked by LY341495. These results suggest that a progressive increase in tonic mGluR activity during postnatal development contributes to a reduction of release probability in excitatory cortical synapses. They also indicate that glutamate transporter activity in the neocortex decreases during postnatal development. This may play a role in increasing tonic activity of mGluRs by increasing ambient glutamate levels in the perisynaptic extracellular space.
Critical role for transcription factor AP-2α in human trophoblast differentiation
Authors: Cheng You-Hong , Aronow Bruce J. , Hossain Shaikh , Trapnell Bruce , Kong Sue , Handwerger Stuart
Published: March 2004

To examine whether AP-2α is a critical component of the genetic program that directs human trophoblast differentiation, we used DNA microarray analyses to characterize the effects of a dominant-negative form of the AP-2 protein upon in vitro differentiating cytotrophoblast cells. Human cytotrophoblast cells (>95% pure) were cultured for 3 days in the presence of control medium or medium containing an adenovirus that expresses a dominant-negative mutant of AP-2 (Ad2.AP-2D/N) or an adenovirus lacking the AP-2 mutant gene (Ad.WT). DNA microarray analyses using Affymetrix human U95Av2 GeneChips were performed on RNA extracted from the three groups of cells immediately prior to and after 3 days of cell culture. Cells infected with Ad2.AP-2D/N or Ad2.WT underwent morphological differentiation similar to that of uninfected cells, with greater than 90% of the cells in each group fusing to form multinucleated syncytiotrophoblast cells. However, Ad2.AP-2D/N markedly inhibited the induction or repression of many genes that were regulated in the noninfected and Ad2.WT-infected cells during differentiation. Eighteen of the 25 most induced genes and 17 of the 20 most repressed genes during differentiation were AP-2 dependent, with the majority of these related to extracellular organization, cellular communication, and signal transduction. Taken together, these findings strongly suggest that AP-2 plays a critical role for both the induction and repression of genes that comprise postsyncytialization gene expression programs of trophoblast differentiation and maturation. AP-2, however, is not required for the fusion of cytotrophoblast cells to form a syncytium or the expression of syncytin.
Expression of an angiotensin-(1–7)-producing fusion protein produces cardioprotective effects in rats
Authors: Santos Robson A. S. , Ferreira Anderson J. , Nadu Ana Paula , Braga Aline N. G. , de Almeida Alvair Pinto , Campagnole-Santos Maria José , Baltatu Ovidiu , Iliescu Radu , Reudelhuber Timothy L. , Bader Michael
Published: March 2004

Angiotensin-(1–7) [ANG-(1–7)] is a recently described heptapeptide product of the renin-angiotensin system. Because biosynthesis of ANG-(1–7) increases in animals treated with cardioprotective drugs and inactivation of the gene for angiotensin converting enzyme 2 [an enzyme involved in the biosynthesis of ANG-(1–7)] leads to the development of cardiac dysfunction, it has been suggested that ANG-(1–7) has cardioprotective properties. To directly test this possibility, we have generated transgenic rats that chronically overproduce ANG-(1–7) by using a novel fusion protein methodology. TGR(A1–7)3292 rats show testicular-specific expression of a cytomegalovirus promoter-driven transgene, resulting in a doubling of circulating ANG-(1–7) compared with nontransgenic control rats. Radiotelemetry hemodynamic measurements showed that transgenic rats presented a small but significant increase in daily and nocturnal heart rate and a slight but significant increase in daily and nocturnal cardiac contractility estimated by dP/d t measurements. Strikingly, TGR(A1–7)3292 rats were significantly more resistant than control animals to induction of cardiac hypertrophy by isoproterenol. In addition, transgenic rats showed a reduced duration of reperfusion arrhythmias and an improved postischemic function in isolated Langendorff heart preparations. These results support a cardioprotective role for circulating ANG-(1–7) and provide a novel tool for evaluating the functional role of ANG-(1–7).
On the existence of a non‐zero lower bound for the number ofGoldbach partitions of an even integer
Authors: Davis Simon
Published: March 2004

The Goldbach partitions of an even number, given by the sums of
two prime addends, form the nonempty set for all integers
2n

with 2 ≤ n ≤ 2 × 1014. It will be shown how to
determine by the method of induction the existence of a non‐zero
lower bound for the number of Goldbach partitions of all even
integers greater than or equal to 4. The proof depends on contour
arguments for complex functions in the unit disk.
Convergence theorems for uniformly quasi‐Lipschitzian mappings
Authors: Zhou Haiyun , Kang Jung Im , Kang Shin Min , Cho Yeol Je
Published: March 2004

We prove some convergence theorems of the modified Ishikawa
iterative sequence with errors for uniformly quasi‐Lipschitzian
mappings in metric spaces. Our results generalize and improve the
corresponding results of Petryshyn and Williamson, Ghosh and
Debnath, Liu, and many others.
Quaternionic representation of the moving frame for surfaces inEuclidean three‐space and Lax pair
Authors: Bracken Paul
Published: March 2004

The moving frame and associated Gauss‐Codazzi equations for
surfaces in three‐space are introduced. A quaternionic
representation is used to identify the Gauss‐Weingarten equation
with a particular Lax representation. Several examples are given,
such as the case of constant mean curvature.
Thermal Treatment Attenuates Neointimal Thickening With Enhanced Expression of Heat-Shock Protein 72 and Suppression of Oxidative Stress
Authors: Okada Motoi , Hasebe Naoyuki , Aizawa Yoshiaki , Izawa Kazuma , Kawabe Jun-ichi , Kikuchi Kenjiro
Published: March 2004

Background—

The beneficial effects of thermal therapy have been reported in several cardiovascular diseases. However, it is unknown whether the thermal treatment has some beneficial roles against the development of atherosclerosis.

Methods and Results—

The inflammatory arterial lesion was introduced by placement of a polyethylene cuff on femoral arteries of male Sprague-Dawley rats for 4 weeks. Thermal-treated group underwent daily bathing in 41°C hot water for 15 minutes. Neointimal thickening along with immunohistochemical expression of heat-shock proteins (HSPs), monocyte chemoattractant protein-1 (MCP-1), and NADPH oxidase were compared with those of a thermally untreated (Control) group. Morphometric analysis demonstrated a significant suppression of neointimal thickening in thermal-treated group compared with the Control group (intimal/medial area ratios, 0.01±0.01 versus 0.31±0.04,
P
<0.01). Expression of MCP-1 and infiltration of ED-positive cells were enhanced in the adventitial layer of Control. More importantly, expression of HSP72 in media was enhanced by thermal treatment. Expression of p22-phox, the major membrane subunit of NADPH oxidase, and MCP-1 was augmented in cuff-injured adventitia of the Control but not the thermal-treated groups.

Conclusions—

Thermal treatment significantly attenuated infiltration of inflammatory cells in adventitia and suppressed neointimal thickening in cuff-injured arteries with the enhancement of HSP72 expression and suppression of oxidative stress.
Targeted β-Adrenergic Receptor Kinase (βARK1) Inhibition by Gene Transfer in Failing Human Hearts
Authors: Williams Matthew L. , Hata Jonathan A. , Schroder Jacob , Rampersaud Edward , Petrofski Jason , Jakoi Andre , Milano Carmelo A. , Koch Walter J.
Published: March 2004

Background—

Failing human myocardium is characterized by an attenuated contractile response to β-adrenergic receptor (βAR) stimulation due to changes in this signaling cascade, including increased expression and activity of the β-adrenergic receptor kinase (βARK1). This leads to desensitization and downregulation of βARs. Previously, expression of a peptide inhibitor of βARK1 (βARKct) has proven beneficial in several animal models of heart failure (HF).

Methods and Results—

To test the hypothesis that inhibition of βARK1 could improve β-adrenergic signaling and contractile function in failing human myocytes, the βARKct was expressed via adenovirus-mediated (AdβARKct) gene transfer in ventricular myocytes isolated from hearts explanted from 10 patients with end-stage HF undergoing cardiac transplantation. AdβARKct also contained the marker gene, green fluorescent protein, and successful gene transfer was confirmed via fluorescence and immunoblotting. Compared with uninfected failing myocytes (control), the velocities of both contraction and relaxation in the AdβARKct-treated cells were increased in response to the β-agonist isoproterenol (contraction: 57.5±6.6% versus 37.0±4.2% shortening per second,
P
<0.05; relaxation: 43.8±5.5% versus 27.5±3.9% lengthening per second,
P
<0.05). Fractional shortening was similarly enhanced (12.2±1.2% versus 8.0±0.9%,
P
<0.05). Finally, adenylyl cyclase activity in response to isoproterenol was also increased in AdβARKct-treated myocytes.

Conclusions—

These results demonstrate that as in animal models of HF, expression of the βARKct can improve contractile function and β-adrenergic responsiveness in failing human myocytes. Thus, βARK1 inhibition may represent a therapeutic strategy for human HF.
Left Cardiac Sympathetic Denervation in the Management of High-Risk Patients Affected by the Long-QT Syndrome
Authors: Schwartz Peter J. , Priori Silvia G. , Cerrone Marina , Spazzolini Carla , Odero Attilio , Napolitano Carlo , Bloise Raffaella , De Ferrari Gaetano M. , Klersy Catherine , Moss Arthur J. , Zareba Wojciech , Robinson Jennifer L. , Hall W. Jackson , Brink Paul A. , Toivonen Lauri , Epstein Andrew E. , Li Cuilan , Hu Dayi
Published: March 2004

Background—

The management of long-QT syndrome (LQTS) patients who continue to have cardiac events (CEs) despite β-blockers is complex. We assessed the long-term efficacy of left cardiac sympathetic denervation (LCSD) in a group of high-risk patients.

Methods and Results—

We identified 147 LQTS patients who underwent LCSD. Their QT interval was very prolonged (QTc, 543±65 ms); 99% were symptomatic; 48% had a cardiac arrest; and 75% of those treated with β-blockers remained symptomatic. The average follow-up periods between first CE and LCSD and post-LCSD were 4.6 and 7.8 years, respectively. After LCSD, 46% remained asymptomatic. Syncope occurred in 31%, aborted cardiac arrest in 16%, and sudden death in 7%. The mean yearly number of CEs per patient dropped by 91% (
P
<0.001). Among 74 patients with only syncope before LCSD, all types of CEs decreased significantly as in the entire group, and a post-LCSD QTc <500 ms predicted very low risk. The percentage of patients with >5 CEs declined from 55% to 8% (
P
<0.001). In 5 patients with preoperative implantable defibrillator and multiple discharges, the post-LCSD count of shocks decreased by 95% (
P
=0.02) from a median number of 25 to 0 per patient. Among 51 genotyped patients, LCSD appeared more effective in LQT1 and LQT3 patients.

Conclusions—

LCSD is associated with a significant reduction in the incidence of aborted cardiac arrest and syncope in high-risk LQTS patients when compared with pre-LCSD events. However, LCSD is not entirely effective in preventing cardiac events including sudden cardiac death during long-term follow-up. LCSD should be considered in patients with recurrent syncope despite β-blockade and in patients who experience arrhythmia storms with an implanted defibrillator.
Compound Mutations
Authors: Westenskow Peter , Splawski Igor , Timothy Katherine W. , Keating Mark T. , Sanguinetti Michael C.
Published: March 2004

Background—

Long QT syndrome (LQTS) predisposes affected individuals to sudden death from cardiac arrhythmias. Although most LQTS individuals do not have cardiac events, significant phenotypic variability exists within families. Probands can be very symptomatic. The mechanism of this phenotypic variability is not understood.

Methods and Results—

Genetic analyses of KVLQT1,
HERG
,
KCNE1
,
KCNE2
, and
SCN5A
detected compound mutations in 20 of 252 LQTS probands (7.9%). Carriers of 2 mutations had longer QTc intervals (527±54 versus 489±44 ms;
P
<0.001); all had experienced cardiac events (20 of 20 [100%] versus 128 of 178 [72%];
P
<0.01) and were 3.5-fold more likely to have cardiac arrest (9 of 16 [56%] versus 45 of 167 [27%];
P
<0.01; OR, 3.5; 95% CI, 1.2 to 9.9) compared with probands with 1 or no identified mutation. Two-microelectrode voltage clamp of
Xenopus
oocytes was used to characterize the properties of variant slow delayed rectifier potassium (
I
Ks
) channels identified in 7 of the probands. When wild-type and variant subunits were coexpressed in appropriate ratios to mimic the genotype of the proband, the reduction in
I
Ks
density was equivalent to the additive effects of the single mutations.

Conclusions—

LQTS-associated compound mutations cause a severe phenotype and are more common than expected. Individuals with compound mutations need to be identified, and their management should be tailored to their increased risk for arrhythmias.
p38 Mitogen-Activated Protein Kinase Contributes to the Diminished Aortic Contraction by Endothelin-1 in DOCA-Salt Hypertensive Rats
Authors: Kim Bokyung , Kim Junghwan , Bae Young M. , Cho Sung I. , Kwon Seong C. , Jung Jin Y , Park Jung -C. , Ahn Hee Y.
Published: March 2004

We investigated whether the diminished contractile responsiveness to endothelin-1 (ET-1) is associated with the altered activation of mitogen-activated protein kinase (MAPK) in aortic smooth muscles from deoxycorticosterone acetate (DOCA)-salt hypertensive rats. ET-1 dose-dependently increased contractions in aortic smooth muscle strips, and the contractions were significantly attenuated in tissues from DOCA-salt hypertensive rats compared with those from sham-operated rats. The phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 was elevated by ET-1, with the magnitude and time-course being similar between strips. Although ET-1 also increased the phosphorylation of p38 MAPK in both strips, the increment was markedly lower in the strips from DOCA-salt hypertensive rats compared with sham-operated controls. 5-Hydroxytryptamine (5-HT) increased vascular contraction and phosphorylation of both MAPK isoforms; these were greater in DOCA-salt hypertensive rats than in sham-operated rats. ET-1 also increased the phosphorylation of caldesmon, an actin-binding protein, in sham-operated and DOCA-salt hypertensive rats. However, the increment was markedly lower in the strips from DOCA-salt hypertensive rats compared with sham-operated controls. The phosphorylation of MAPK isoforms and caldesmon elevated by ET-1 was inhibited by PD098059, an inhibitor of ERK1/2 kinase, and SB203580, an inhibitor of p38 MAPK, respectively. These results suggest that ET-1 and 5-HT induce contraction by activating the MAPK pathway in rat aortic smooth muscle and that the diminished responsiveness to ET-1 in the DOCA-salt hypertensive rat may be, in part, mediated by the decrease of caldesmon phosphorylation after the decreased activation of p38 MAPK.
Cardiomyocyte-Specific Overexpression of Nitric Oxide Synthase 3 Improves Left Ventricular Performance and Reduces Compensatory Hypertrophy After Myocardial Infarction
Authors: Janssens Stefan , Pokreisz Peter , Schoonjans Luc , Pellens Marijke , Vermeersch Pieter , Tjwa Marc , Jans Peter , Scherrer-Crosbie Marielle , Picard Michael H. , Szelid Zsolt , Gillijns Hilde , Van de Werf Frans , Collen Desire , Bloch Kenneth D.
Published: March 2004

Nitric oxide (NO) is an important modulator of cardiac performance and left ventricular (LV) remodeling after myocardial infarction (MI). We tested the effect of cardiomyocyte-restricted overexpression of one NO synthase isoform, NOS3, on LV remodeling after MI in mice. LV structure and function before and after permanent LAD coronary artery ligation were compared in transgenic mice with cardiomyocyte-restricted NOS3 overexpression (NOS3-TG) and their wild-type littermates (WT). Before MI, systemic hemodynamic measurements, echocardiographic assessment of LV fractional shortening (FS), heart weight, and myocyte width (as assessed histologically) did not differ in NOS3-TG and WT mice. The inotropic response to graded doses of isoproterenol was significantly reduced in NOS3-TG mice. One week after LAD ligation, the infarcted fraction of the LV did not differ in WT and NOS3-TG mice (34±4% versus 36±12%, respectively). Four weeks after MI, however, end-systolic LVID was greater, and fractional shortening and maximum and minimum rates of LV pressure development were less in WT than in NOS3-TG mice. LV weight/body weight ratio was greater in WT than in NOS3-TG mice (5.3±0.2 versus 4.6±0.5 mg/g;
P
<0.01). Myocyte width in noninfarcted myocardium was greater in WT than in NOS3-TG mice (18.8±2.0 versus 16.6±1.6 μm;
P
<0.05), whereas fibrosis in noninfarcted myocardium was similar in both genotypes. Cardiomyocyte-restricted overexpression of NOS3 limits LV dysfunction and remodeling after MI, in part by decreasing myocyte hypertrophy in noninfarcted myocardium.
Hospital Usage of Early Do-Not-Resuscitate Orders and Outcome After Intracerebral Hemorrhage
Authors: Hemphill J. Claude , Newman Jeffrey , Zhao Shoujun , Johnston S. Claiborne
Published: March 2004

Background and Purpose—

Do-not-resuscitate (DNR) orders are commonly used after severe stroke. We hypothesized that there is significant variability in how these orders are applied after intracerebral hemorrhage and that this influences outcome.

Methods—

From a database of all admissions to nonfederal hospitals in California, discharge abstracts were obtained for all patients with a primary diagnosis of intracerebral hemorrhage who were admitted through the emergency department during 1999 and 2000. Characteristics included whether DNR orders were written within the first 24 hours of hospitalization. Case-mix–adjusted hospital DNR use was calculated for each hospital by comparing the actual number of DNR cases with the number predicted from a multivariable model. Outcome (in-hospital death) was evaluated in a separate multivariable model adjusted for individual and hospital characteristics.

Results—

A total of 8233 patients were treated in 234 hospitals. The percentage of patients with DNR orders varied from 0% to 70% across hospitals. Being treated in a hospital that used DNR orders 10% more often than another hospital with a similar case mix increased a patient’s odds of dying during hospitalization by 13% (
P
<0.001). Patients treated in the quartile of hospitals with the highest adjusted DNR use were more likely to die, and this was not just because of individual patient DNR status.

Conclusions—

In-hospital mortality after intracerebral hemorrhage is significantly influenced by the rate at which treating hospitals use DNR orders, even after adjusting for case mix. This is not due solely to individual patient DNR status, but rather some other aspect of overall care.
Peripheral CD4+CD8+ T cells are differentiated effector memory cells with antiviral functions
Authors: Nascimbeni Michelina , Shin Eui-Cheol , Chiriboga Luis , Kleiner David E. , Rehermann Barbara
Published: March 2004

Although an increased frequency of CD4+CD8+ T cells has been observed in the peripheral blood during viral infections, their role, function, and biologic significance are still poorly understood. Here we demonstrate that the circulating CD4+CD8+ T-cell population contains mature effector memory lymphocytes specific for antigens of multiple past, latent, and high-level persistent viral infections. Upon in vitro antigenic challenge, a higher frequency of CD4+CD8+ than single-positive cells displayed a T helper 1/T cytotoxic 1 (Th1/Tc1) cytokine profile and proliferated. Ex vivo, more double-positive than single-positive cells exhibited a differentiated phenotype. Accordingly, their lower T-cell receptor excision circles (TREC) content and shorter telomeres proved they had divided more frequently than single-positive cells. Consistent with expression of the tissue-homing marker CXCR3, CD4+CD8+ T cells were demonstrated in situ at the site of persistent viral infection (ie, in the liver during chronic hepatitis C). Finally, a prospective analysis of hepatitis C virus (HCV) infection in a chimpanzee, the only animal model for HCV infection, showed a close correlation between the frequency of activated CD4+CD8+ T cells and viral kinetics. Collectively, these findings demonstrate that peripheral CD4+CD8+ T cells take part in the adaptive immune response against infectious pathogens and broaden the perception of the T-cell populations involved in antiviral immune responses. (Blood. 2004;104:478-486)
Interleukin-1β but not IL-1α binds to fibrinogen and fibrin and has enhanced activity in the bound form
Authors: Sahni Abha , Guo Min , Sahni Sanjeev K. , Francis Charles W.
Published: March 2004

Fibrin is formed at sites of injury or inflammation and provides the temporary matrix to support vascular cell responses that are also mediated by cytokines including interleukin-1 (IL-1). We have shown previously that fibroblast growth factor 2 (FGF-2) binds with high affinity to fibrin(ogen). Because IL-1 has a structure similar to FGF-2, we have investigated the possible binding of IL-1 to fibrin(ogen). Experiments using IL-1 immobilized on Sepharose beads and soluble iodine 125 (125I)-labeled fibrinogen demonstrated no specific interaction of IL-1α with fibrinogen, but IL-1β showed saturable and specific binding. Scatchard analysis indicated a single binding site with an apparent Kd = 1.5 nM and a maximum molar binding ratio of IL-1β to fibrinogen of 1.8:1. Binding of 125I-IL-1β to Sepharose-immobilized fibrinogen also demonstrated a single binding site with an apparent Kd of 3.5 nM. IL-1β also bound specifically to fibrin monomer and polymerized fibrin with apparent Kds of 3.4 nM and 2.3 nM, respectively. IL-1β displaced FGF-2 for binding to fibrin, indicating an interaction with the same or a closely related site. Compared with free form, fibrinogen-bound IL-1β stimulated increased activation of endothelial cell nuclear factor κB (NF-κB), monocyte chemoattractant protein-1 (MCP-1) secretion, and nitric oxide (NO) synthesis. We conclude that IL-1β binds with high affinity to fibrin(ogen) and demonstrates increased activity in the bound form. (Blood. 2004; 104:409-414)
Estrogen Receptor β-Mediated Inhibition of Male Germ Cell Line Development in Mice by Endogenous Estrogens during Perinatal Life
Authors: Delbès Géraldine , Levacher Christine , Pairault Catherine , Racine Chrystèle , Duquenne Clotilde , Krust Andrée , Habert René
Published: March 2004

Epidemiological, clinical, and experimental studies have suggested that excessive exposure to estrogens during fetal/neonatal life can lead to reproductive disorders and sperm abnormalities in adulthood. However, it is unknown whether endogenous concentrations of estrogens affect the establishment of the male fetal germ cell lineage. We addressed this question by studying the testicular development of mice in which the estrogen receptor (ER) β or the ERα gene was inactivated. The homozygous inactivation of ERβ (ERβ−/−) increased the number of gonocytes by 50% in 2- and 6-d-old neonates. The numbers of Sertoli and Leydig cells and the level of testicular testosterone production were unaffected, suggesting that estrogens act directly on the gonocytes. The increase in the number of gonocytes did not occur during fetal life but instead occurred just after birth, when gonocytes resumed mitosis and apoptosis. It seems to result from a decrease in the apoptosis rate evaluated by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling method and cleaved caspase-3 immunohistochemical detection. Last, mice heterozygous for the ERβ gene inactivation behaved similarly to their ERβ−/− littermates in terms of the number of gonocytes, apoptosis, and mitosis, suggesting that these cells are highly sensitive to the binding of estrogens to ERβ. ERα inactivation had no effect on the number of neonatal gonocytes and Sertoli cells. In conclusion, this study provides the first demonstration that endogenous estrogens can physiologically inhibit germ cell growth in the male. This finding may have important implications concerning the potential action of environmental estrogens.
Direct and Indirect Effects of Aldosterone on Cyclooxygenase-2 and Interleukin-6 Expression in Rat Cardiac Cells in Culture and after Myocardial Infarction
Authors: Rebsamen Michela C. , Perrier Emeline , Gerber-Wicht Christine , Benitah Jean-Pierre , Lang Ursula
Published: March 2004

Aldosterone contributes to cardiac failure, which is associated with induction of inflammatory mediators. Moreover, aldosterone was shown to induce a vascular inflammatory phenotype in the rat heart. Using Western blotting and/or real-time RT-PCR, we examined the effect of aldosterone on the expression of the proinflammatory molecules, cyclooxygenase-2 (COX-2), and IL-6 in neonatal rat ventricular cardiac myocytes and fibroblasts as well as in adult cardiomyocytes after myocardial infarction. In cardiomyocytes, aldosterone induced COX-2 but not IL-6 expression. After 4–18 h of stimulation with 1 μm aldosterone, a significant increase in COX-2 protein expression was observed, preceded by an increase of COX-2 mRNA levels. After 18 h treatment, 100 nm and 1 μm aldosterone increased COX-2 protein amount by 2- and 4-fold, respectively. Consistently, aldosterone increased by 2.5-fold prostaglandin E2 secretion in cardiomyocytes. In cardiac fibroblasts, aldosterone increased neither COX-2 nor IL-6 mRNA expression. Interestingly, prostaglandin E2 (100 nm) strongly induced both proinflammatory molecules in fibroblasts and cardiomyocytes. Our results indicate that aldosterone directly induces COX-2 expression in cardiomyocytes and suggest that the subsequent increase in prostaglandin secretion may act in an autocrine and/or paracrine manner inducing in turn COX-2 and IL-6 expression. In vivo, myocardial infarction strongly increased both COX-2 and IL-6 expression in ventricular cardiomyocytes. Administration of the aldosterone antagonist RU28318 completely prevented COX-2 induction by infarction and partially inhibited the increase in IL-6 mRNA. These data suggest that after myocardial infarction, mineralocorticoid receptor activity is responsible for COX-2 induction and indirectly participates in IL-6 expression in cardiomyocytes.
Loss-of-Function Mutation of the Galanin Gene Is Associated with Perturbed Islet Function in Mice
Authors: Ahrén Bo , Pacini Giovanni , Wynick David , Wierup Nils , Sundler Frank
Published: March 2004

The neuropeptide galanin is expressed in sympathetic nerve terminals that surround islet cells and inhibits insulin secretion. To explore its role for islet function, we studied mice with a loss-of-function mutation in the galanin gene [galanin knockout (KO) mice]. Intravenous 2-deoxy-glucose, which activates both the sympathetic and parasympathetic branches of the autonomic nervous system, caused an initial (1–5 min) inhibition of insulin secretion that was impaired in galanin KO mice (P = 0.027), followed by a subsequent stimulation of insulin secretion that was augmented in galanin KO mice (P < 0.01). Similar effects were seen after chemical sympathectomy by 6-hydroxydopamine. In contrast, galanin KO mice had a reduced insulin response to glucose, both in vivo (P < 0.001) and in isolated islets (P < 0.001), and to arginine, both in vivo (P = 0.012) and in vitro (P = 0.018). During an iv glucose tolerance test, galanin KO mice had impaired glucose disposal (P = 0.005) due to a reduced insulin response (P < 0.001) and a reduced insulin-independent glucose elimination (glucose effectiveness; P = 0.040). Insulin sensitivity, as judged by a euglycemic, hyperinsulinemic clamp technique, was slightly increased in galanin KO mice (P = 0.032). We conclude that 1) galanin may contribute to sympathetic influences inhibiting insulin secretion in mice, and 2) galanin KO mice have a reduced glucose-induced insulin secretion.
Minireview: Gut Peptides Regulating Satiety
Authors: Druce Maralyn R. , Small Caroline J. , Bloom Stephen R.
Published: March 2004

The gastrointestinal tract and the pancreas release hormones regulating satiety and body weight. Ghrelin stimulates appetite, and glucagon-like peptide-1, oxyntomodulin, peptide YY, cholecystokinin, and pancreatic polypeptide inhibit appetite. These gut hormones act to markedly alter food intake in humans and rodents. Obesity is the current major cause of premature death in the United Kingdom, killing almost 1000 people per week. Worldwide, its prevalence is accelerating. There is currently no effective answer to the pandemic of obesity, but replacement of the low levels of peptide YY observed in the obese may represent an effective antiobesity therapy.
Physical and Functional Interaction of Growth Hormone and Insulin-Like Growth Factor-I Signaling Elements
Authors: Huang Yao , Kim Sung-Oh , Yang Ning , Jiang Jing , Frank Stuart J.
Published: March 2004

GH and IGF-I are critical regulators of growth and metabolism. GH interacts with the GH receptor (GHR), a cytokine superfamily receptor, to activate the cytoplasmic tyrosine kinase, Janus kinase 2 (JAK2), and initiate intracellular signaling cascades. IGF-I, produced in part in response to GH, binds to the heterotetrameric IGF-I receptor (IGF-IR), which is an intrinsic tyrosine kinase growth factor receptor that triggers proliferation, antiapoptosis, and other biological actions. Previous in vitro and overexpression studies have suggested that JAKs may interact with IGF-IR and that IGF-I stimulation may activate JAKs. In this study, we explore interactions between GHR-JAK2 and IGF-IR signaling pathway elements utilizing the GH and IGF-I-responsive 3T3-F442A and 3T3-L1 preadipocyte cell lines, which endogenously express both the GHR and IGF-IR. We find that GH induces formation of a complex that includes GHR, JAK2, and IGF-IR in these preadipocytes. The assembly of this complex in intact cells is rapid, GH concentration dependent, and can be prevented by a GH antagonist, G120K. However, it is not inhibited by the kinase inhibitor, staurosporine, which markedly inhibits GHR tyrosine phosphorylation. Moreover, complex formation does not appear dependent on GH-induced activation of the ERK or phosphatidylinositol 3-kinase signaling pathways or on the tyrosine phosphorylation of GHR, JAK2, or IGF-IR. These results suggest that GH-induced formation of the GHR-JAK2-IGF-IR complex is governed instead by GH-dependent conformational change(s) in the GHR and/or JAK2. We further demonstrate that GH and IGF-I can synergize in acute aspects of signaling and that IGF-I enhances GH-induced assembly of conformationally active GHRs. These findings suggest the existence of previously unappreciated relationships between these two hormones.
Transient activation of β-catenin signalling in adult mouse epidermis is sufficient to induce new hair follicles but continuous activation is required to maintain hair follicle tumours
Authors: Celso Cristina Lo , Prowse David M. , Watt Fiona M.
Published: March 2004

When β-catenin signalling is disturbed from mid-gestation onwards lineage commitment is profoundly altered in postnatal mouse epidermis. We have investigated whether adult epidermis has the capacity forβ-catenin-induced lineage conversion without prior embryonic priming. We fused N-terminally truncated, stabilised β-catenin to the ligand-binding domain of a mutant oestrogen receptor (ΔNβ-cateninER).ΔNβ-cateninER was expressed in the epidermis of transgenic mice under the control of the keratin 14 promoter and β-catenin activity was induced in adult epidermis by topical application of 4-hydroxytamoxifen(4OHT). Within 7 days of daily 4OHT treatment resting hair follicles were recruited into the hair growth cycle and epithelial outgrowths formed from existing hair follicles and from interfollicular epidermis. The outgrowths expressed Sonic hedgehog, Patched and markers of hair follicle differentiation, indicative of de novo follicle formation. The interfollicular epidermal differentiation program was largely unaffected but after an initial wave of sebaceous gland duplication sebocyte differentiation was inhibited. A single application of 4OHT was as effective as repeated doses in inducing new follicles and growth of existing follicles. Treatment of epidermis with 4OHT for 21 days resulted in conversion of hair follicles to benign tumours resembling trichofolliculomas. The tumours were dependent on continuous activation of β-catenin and by 28 days after removal of the drug they had largely regressed. We conclude that interfollicular epidermis and sebaceous glands retain the ability to be reprogrammed in adult life and that continuousβ-catenin signalling is required to maintain hair follicle tumours.
Inhibition of the cell cycle is required for convergent extension of the paraxial mesoderm during Xenopus neurulation
Authors: Leise Walter F. , Mueller Paul R.
Published: March 2004

Coordination of morphogenesis and cell proliferation is essential during development. In Xenopus, cell divisions are rapid and synchronous early in development but then slow and become spatially restricted during gastrulation and neurulation. One tissue that transiently stops dividing is the paraxial mesoderm, a dynamically mobile tissue that forms the somites and body musculature of the embryo. We have found that cessation of cell proliferation is required for the proper positioning and segmentation of the paraxial mesoderm as well as the complete elongation of the Xenopusembryo. Instrumental in this cell cycle arrest is Wee2, a Cdk inhibitory kinase that is expressed in the paraxial mesoderm from mid-gastrula stages onwards. Morpholino-mediated depletion of Wee2 increases the mitotic index of the paraxial mesoderm and this results in the failure of convergent extension and somitogenesis in this tissue. Similar defects are observed if the cell cycle is inappropriately advanced by other mechanisms. Thus, the low mitotic index of the paraxial mesoderm plays an essential function in the integrated cell movements and patterning of this tissue.
Disruption of ferroportin 1 regulation causes dynamic alterations in iron homeostasis and erythropoiesis in polycythaemia mice
Authors: Mok Henry , Jelinek Jaroslav , Pai Sonia , Cattanach Bruce M. , Prchal Josef T. , Youssoufian Hagop , Schumacher Armin
Published: March 2004

Coding region mutations in the principal basolateral iron transporter of the duodenal enterocyte, ferroportin 1 (FPN1), lead to autosomal dominant reticuloendothelial iron overload in humans. We report the positional cloning of a hypermorphic, regulatory mutation in Fpn1 from radiation-induced polycythaemia (Pcm) mice. A 58 bp microdeletion in the Fpn1promoter region alters transcription start sites and eliminates the iron responsive element (IRE) in the 5′ untranslated region, resulting in increased duodenal and hepatic Fpn1 protein levels during early postnatal development. Pcm mutants, which are iron deficient at birth,exhibited increased Fpn1-mediated iron uptake and reticuloendothelial iron overload as young adult mice. Additionally, Pcm mutants displayed an erythropoietin (Epo)-dependent polycythemia in heterozygotes and a hypochromic, microcytic anemia in homozygotes. Interestingly, both defects in erythropoiesis were transient, correcting by young adulthood. Delayed upregulation of the negative hormonal regulator of iron homeostasis, hepcidin(Hamp), during postnatal development correlates strongly with profound increases in Fpn1 protein levels and polycythemia in Pcmheterozygotes. Thus, our data suggest that a Hamp-mediated regulatory interference alleviates the defects in iron homeostasis and transient alterations in erythropoiesis caused by a regulatory mutation in Fpn1.
LDL receptor-related proteins 5 and 6 in Wnt/β-catenin signaling:Arrows point the way
Authors: He Xi , Semenov Mikhail , Tamai Keiko , Zeng Xin
Published: March 2004

Wnt signaling through the canonical β-catenin pathway plays essential roles in development and disease. Low-density-lipoprotein receptor-related proteins 5 and 6 (Lrp5 and Lrp6) in vertebrates, and their Drosophila ortholog Arrow, are single-span transmembrane proteins that are indispensable for Wnt/β-catenin signaling, and are likely to act as Wnt co-receptors. This review highlights recent progress and unresolved issues in understanding the function and regulation of Arrow/Lrp5/Lrp6 in Wnt signaling. We discuss Arrow/Lrp5/Lrp6 interactions with Wnt and the Frizzled family of Wnt receptors, and with the intracellular β-catenin degradation apparatus. We also discuss the regulation of Lrp5/Lrp6 by other extracellular ligands, and LRP5 mutations associated with familial osteoporosis and other disorders.