bluuebunny/crossref_metadata_2025 huggingface dataset:
Animal models of chronic obstructive pulmonary disease
Authors: Wright Joanne L. , Cosio Manuel , Churg Andrew
Published: May 2008

The mechanisms involved in the genesis of chronic obstructive pulmonary disease (COPD) are poorly defined. This area is complicated and difficult to model because COPD consists of four separate anatomic lesions (emphysema, small airway remodeling, pulmonary hypertension, and chronic bronchitis) and a functional lesion, acute exacerbation; moreover, the disease in humans develops over decades. This review discusses the various animal models that have been used to attempt to recreate human COPD and the advantages and disadvantages of each. None of the models reproduces the exact changes seen in humans, but cigarette smoke-induced disease appears to come the closest, and genetically modified animals also, in some instances, shed light on processes that appear to play a role.
Effects of dietary protein content on IGF-I, testosterone, and body composition during 8 days of severe energy deficit and arduous physical activity
Authors: Alemany Joseph A. , Nindl Bradley C. , Kellogg Mark D. , Tharion William J. , Young Andrew J. , Montain Scott J.
Published: May 2008

Energy restriction coupled with high energy expenditure from arduous work is associated with an altered insulin-like growth factor-I (IGF-I) system and androgens that are coincident with losses of fat-free mass. The aim of this study was to determine the effects of two levels of dietary protein content and its effects on IGF-I, androgens, and losses of fat-free mass accompanying energy deficit. We hypothesized that higher dietary protein content would attenuate the decline of anabolic hormones and, thus, prevent losses of fat-free mass. Thirty-four men [24 (SD 0.3) yr, 180.1 (SD 1.1) cm, and 83.0 (SD 1.4) kg] participated in an 8-day military exercise characterized by high energy expenditure (16.5 MJ/day), low energy intake (6.5 MJ/day), and sleep deprivation (4 h/24 h) and were randomly divided into two dietary groups: 0.9 and 0.5 g/kg dietary protein intake. IGF-I system analytes, androgens, and body composition were assessed before and on days 4 and 8 of the intervention. Total, free, and nonternary IGF-I and testosterone declined 50%, 64%, 55%, and 45%, respectively, with similar reductions in both groups. There was, however, a diet × time interaction on day 8 for total IGF-I and sex hormone-binding globulin. Decreases in body mass (3.2 kg), fat-free mass (1.2 kg), fat mass (2.0 kg), and percent body fat (1.5%) were similar in both groups ( P = 0.01). Dietary protein content of 0.5 and 0.9 g/kg minimally attenuated the decline of IGF-I, the androgenic system, and fat-free mass during 8 days of negative energy balance associated with high energy expenditure and low energy intake.
Quantitative analysis of serum sodium concentration after prolonged running in the heat
Authors: Baker Lindsay B. , Lang James A. , Kenney W. Larry
Published: May 2008

This study compared measured serum [Na+] (S[Na+]; brackets denote concentration) with that predicted by the Nguyen-Kurtz equation after manipulating ingested [Na+] and changes in body mass (ΔBM) during prolonged running in the heat. Athletes (4 men, 4 women; 22–36 yr) ran for 2 h, followed by a run to exhaustion and 1-h recovery. During exercise and recovery, subjects drank a 6% carbohydrate solution without Na+(Na+0), 6% carbohydrate solution with 18 mmol/l Na+(Na+18), or 6% carbohydrate solution with 30 mmol/l Na+(Na+30) to maintain BM (0%ΔBM), increase BM by 2%, or decrease BM by 2% or 4% in 12 separate trials. Net fluid, Na+, and K+balance were measured to calculate the Nguyen-Kurtz predicted S[Na+]for each trial. For all beverages, predicted and measured S[Na+]were not significantly different during the 0%, −2%, and −4%ΔBM trials (−0.2 ± 0.2 mmol/l) but were significantly different during the +2%ΔBM trials (−2.6 ± 0.5 mmol/l). Overall, Na+consumption attenuated the decline in S[Na+](−2.0 ± 0.5, −0.9 ± 0.5, −0.5 ± 0.5 mmol/l from pre- to postexperiment of the 0%ΔBM trials for Na+30, Na+18, and Na+0, respectively) but the differences among beverages were not statistically significant. Beverage [Na+] did not affect performance; however, time to exhaustion was significantly shorter during the −4% (8 ± 3 min) and −2% (14 ± 3 min) vs. 0% (22 ± 5 min) and +2% (26 ± 6 min) ΔBM trials. In conclusion, when athletes maintain or lose BM, changes in S[Na+]can be accurately predicted by changes in the mass balance of fluid, Na+, and K+during prolonged running in the heat.
Central nervous adaptations following 1 wk of wrist and hand immobilization
Authors: Lundbye-Jensen Jesper , Nielsen Jens Bo
Published: May 2008

Plastic neural changes have been documented in relation to different types of physical activity, but little is known about central nervous system plasticity accompanying reduced physical activity and immobilization. In the present study we investigated whether plastic neural changes occur in relation to 1 wk of immobilization of the nondominant wrist and hand and a corresponding period of recovery in 10 able-bodied volunteers. After immobilization, maximal voluntary contraction torque decreased and the variability of submaximal static contractions increased significantly without evidence of changes in muscle contractile properties. Hoffmann (H)-reflex amplitudes and the ratios of H-slope to M-slope increased significantly in flexor carpi radialis and abductor pollicis brevis at rest and during contraction without changes in corticospinal excitability, estimated from motor-evoked potentials (MEPs) elicited by transcranial magnetic stimulation. Corticomuscular coherence measures were derived from EEG and EMG obtained during static contractions. After immobilization, corticomuscular coherence in the 15- to 35-Hz range associated with maximum negative cumulant values at lags corresponding to MEP latencies decreased. One week after cast removal, all measurements returned to preimmobilization levels. The increased H-reflex amplitudes without changes in MEPs may suggest that presynaptic inhibition or postactivation depression of Ia afferents is reduced following immobilization. Reduced corticomuscular coherence may be caused by changes in afferent input at spinal and cortical levels or by changes in the descending drive from motor cortex. Further studies are needed to elucidate the mechanisms underlying the observed increased spinal excitability and reduced coupling between motor cortex and spinal motoneuronal activity following immobilization.
Type 5 adenylyl cyclase plays a major role in stabilizing heart rate in response to microgravity induced by parabolic flight
Authors: Okumura Satoshi , Tsunematsu Takashi , Bai Yunzhe , Jiao Qibin , Ono Shinji , Suzuki Sayaka , Kurotani Reiko , Sato Motohiko , Minamisawa Susumu , Umemura Satoshi , Ishikawa Yoshihiro
Published: May 2008

It is well known that autonomic nervous activity is altered under microgravity, leading to disturbed regulation of cardiac function, such as heart rate. Autonomic regulation of the heart is mostly determined by β-adrenergic receptors/cAMP signal, which is produced by adenylyl cyclase, in cardiac myocytes. To examine a hypothesis that a major cardiac isoform, type 5 adenylyl cyclase (AC5), plays an important role in regulating heart rate during parabolic flights, we used transgenic mouse models with either disrupted (AC5KO) or overexpressed AC5 in the heart (AC5TG) and analyzed heart rate variability. Heart rate had a tendency to decrease gradually in later phases within one parabola in each genotype group, but the magnitude of decrease was smaller in AC5KO than that in the other groups. The inverse of heart rate, i.e., the R-R interval, was much more variable in AC5KO and less variable in AC5TG than that in wild-type controls. The standard deviation of normal R-R intervals, a marker of total autonomic variability, was significantly greater in microgravity phase in each genotype group, but the magnitude of increase was much greater in AC5KO than that in the other groups, suggesting that heart rate regulation became unstable in the absence of AC5. In all, AC5 plays a major role in stabilizing heat rate under microgravity.
Recombinant Activated Protein C Attenuates Endothelial Injury and Inhibits Procoagulant Microparticles Release in Baboon Heatstroke
Authors: Bouchama Abderrezak , Kunzelmann Corinne , Dehbi Mohammed , Kwaasi Aaron , Eldali Abdelmoneim , Zobairi Fatiha , Freyssinet Jean-Marie , de Prost Dominique
Published: May 2008

Objectives—

We tested the hypothesis that the antithrombotic and cytoprotective effects of recombinant human activated protein C (rhAPC) protect baboons against the lethal effects of heatstroke.

Methods and Results—

Fourteen anesthetized baboons assigned randomly to rhAPC (n=7) or control group (n=7) were heat-stressed in a prewarmed incubator at 44 to 47°C until systolic blood pressure fell below 90 mm Hg, which signaled severe heatstroke. rhAPC was administered intravenously (24 μg/kg/h) for 12 hours at onset of heatstroke. Heat stress induced coagulation and fibrinolysis activation as evidenced by a significant increase from baseline levels in plasma levels of thrombin-antithrombin (TAT) complexes, tissue plasminogen activator, and D-dimer. Heat stress elicited cell activation/injury as assessed by the release of interleukin (IL)-6, soluble thrombomodulin, and procoagulant microparticles (MPs). rhAPC did not significantly reduce heatstroke-induced thrombin generation, and D-dimer and had no effect on fibrinolytic activity. In contrast, rhAPC infusion attenuated significantly the plasma rise of IL-6 and inhibited the release of soluble thrombomodulin and MPs as compared with control group. No difference in survival was observed between rhAPC-treated and control group.

Conclusions—

rhAPC given to heatstroke baboons provided cytoprotection, but had no effect on heatstroke-induced coagulation activation and fibrin formation. Inhibition of MPs by rhAPC suggested a novel mechanism of action for this protein.
Mertk Receptor Mutation Reduces Efferocytosis Efficiency and Promotes Apoptotic Cell Accumulation and Plaque Necrosis in Atherosclerotic Lesions of
Apoe
−/−
Mice
Authors: Thorp Edward , Cui Dongying , Schrijvers Dorien M. , Kuriakose George , Tabas Ira
Published: May 2008

Objective—

Atherosclerotic plaques that are prone to disruption and acute thrombotic vascular events are characterized by large necrotic cores. Necrotic cores result from the combination of macrophage apoptosis and defective phagocytic clearance (efferocytosis) of these apoptotic cells. We previously showed that macrophages with tyrosine kinase-defective Mertk receptor (Mertk

KD

) have a defect in phagocytic clearance of apoptotic macrophages in vitro. Herein we test the hypothesis that the Mertk

KD

mutation would result in increased accumulation of apoptotic cells and promote necrotic core expansion in a mouse model of advanced atherosclerosis.

Methods and Results—

Mertk

KD

;
Apoe
−/−
mice and control
Apoe
−/−
mice were fed a Western-type diet for 10 or 16 weeks, and aortic root lesions were analyzed for apoptosis and plaque necrosis. We found that the plaques of the
Mertk

KD

;
Apoe
−/−
mice had a significant increase in terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL)-positive apoptotic cells. Most importantly, there were more non-macrophage-associated apoptotic cells in the
Mertk

KD

lesions, consistent with defective efferocytosis. The more advanced (16-week)
Mertk

KD

;
Apoe
−/−
plaques were more necrotic, consistent with a progression from apoptotic cell accumulation to plaque necrosis in the setting of a defective efferocytosis receptor.

Conclusion—

In a mouse model of advanced atherosclerosis, mutation of the phagocytic Mertk receptor promotes the accumulation of apoptotic cells and the formation of necrotic plaques. These data are consistent with the notion that a defect in an efferocytosis receptor can accelerate the progression of atherosclerosis and suggest a novel therapeutic target to prevent advanced plaque progression and its clinical consequences.
Role of Protein Tyrosine Phosphatase 1B in Vascular Endothelial Growth Factor Signaling and Cell–Cell Adhesions in Endothelial Cells
Authors: Nakamura Yoshimasa , Patrushev Nikolay , Inomata Hyoe , Mehta Dolly , Urao Norifumi , Kim Ha Won , Razvi Masooma , Kini Vidisha , Mahadev Kalyankar , Goldstein Barry J. , McKinney Ronald , Fukai Tohru , Ushio-Fukai Masuko
Published: May 2008

Vascular endothelial growth factor (VEGF) binding induces phosphorylation of VEGF receptor (VEGFR)2 in tyrosine, which is followed by disruption of VE-cadherin–mediated cell–cell contacts of endothelial cells (ECs), thereby stimulating EC proliferation and migration to promote angiogenesis. Tyrosine phosphorylation events are controlled by the balance of activation of protein tyrosine kinases and protein tyrosine phosphatases (PTPs). Little is known about the role of endogenous PTPs in VEGF signaling in ECs. In this study, we found that PTP1B expression and activity are markedly increased in mice hindlimb ischemia model of angiogenesis. In ECs, overexpression of PTP1B, but not catalytically inactive mutant PTP1B-C/S, inhibits VEGF-induced phosphorylation of VEGFR2 and extracellular signal-regulated kinase 1/2, as well as EC proliferation, whereas knockdown of PTP1B by small interfering RNA enhances these responses, suggesting that PTP1B negatively regulates VEGFR2 signaling in ECs. VEGF-induced p38 mitogen-activated protein kinase phosphorylation and EC migration are not affected by PTP1B overexpression or knockdown. In vivo dephosphorylation and cotransfection assays reveal that PTP1B binds to VEGFR2 cytoplasmic domain in vivo and directly dephosphorylates activated VEGFR2 immunoprecipitates from human umbilical vein endothelial cells. Overexpression of PTP1B stabilizes VE-cadherin–mediated cell–cell adhesions by reducing VE-cadherin tyrosine phosphorylation, whereas PTP1B small interfering RNA causes opposite effects with increasing endothelial permeability, as measured by transendothelial electric resistance. In summary, PTP1B negatively regulates VEGFR2 receptor activation via binding to the VEGFR2, as well as stabilizes cell–cell adhesions through reducing tyrosine phosphorylation of VE-cadherin. Induction of PTP1B by hindlimb ischemia may represent an important counterregulatory mechanism that blunts overactivation of VEGFR2 during angiogenesis in vivo.
Distinct Cellular and Molecular Mechanisms Underlie Functional Remodeling of Repolarizing K
+
Currents With Left Ventricular Hypertrophy
Authors: Marionneau Céline , Brunet Sylvain , Flagg Thomas P. , Pilgram Thomas K. , Demolombe Sophie , Nerbonne Jeanne M.
Published: May 2008

Left ventricular hypertrophy (LVH) is associated with electric remodeling and increased arrhythmia risk, although the underlying mechanisms are poorly understood. In the experiments here, functional voltage-gated (Kv) and inwardly rectifying (Kir) K
+
channel remodeling was examined in a mouse model of pressure overload–induced LVH, produced by transverse aortic constriction (TAC). Action potential durations (APDs) at 90% repolarization in TAC LV myocytes and QT
c
intervals in TAC mice were prolonged. Mean whole-cell membrane capacitance (
C
m
) was higher, and
I
to,f
,
I
K,slow
,
I
ss
, and
I
K1
densities were lower in TAC, than in sham, LV myocytes. Although the primary determinant of the reduced current densities is the increase in
C
m
,
I
K,slow
amplitudes were decreased and
I
ss
amplitudes were increased in TAC LV cells. Further experiments revealed regional differences in the effects of LVH. Cellular hypertrophy and increased
I
ss
amplitudes were more pronounced in TAC endocardial LV cells, whereas
I
K,slow
amplitudes were selectively reduced in TAC epicardial LV cells. Consistent with the similarities in
I
to,f
and
I
K1
amplitudes, Kv4.2, Kv4.3, and KChIP2 (
I
to,f
), as well as Kir2.1 and Kir2.2 (
I
K1
), transcript and protein expression levels were similar in TAC and sham LV. Unexpectedly, expression of
I
K,slow
channel subunits Kv1.5 and Kv2.1 was increased in TAC LV. Biochemical experiments also demonstrated that, although total protein was unaltered, cell surface expression of TASK1 was increased in TAC LV. Functional changes in repolarizing K
+
currents with LVH, therefore, result from distinct cellular (cardiomyocyte enlargement) and molecular (alterations in the numbers of functional channels) mechanisms.
Adventitial Mast Cells Contribute to Pathogenesis in the Progression of Abdominal Aortic Aneurysm
Authors: Tsuruda Toshihiro , Kato Johji , Hatakeyama Kinta , Kojima Kazushi , Yano Mitsuhiro , Yano Yoshikazu , Nakamura Kunihide , Nakamura-Uchiyama Fukumi , Matsushima Yoshibumi , Imamura Takuroh , Onitsuka Toshio , Asada Yujiro , Nawa Yukifumi , Eto Tanenao , Kitamura Kazuo
Published: May 2008

Abdominal aortic aneurysm (AAA) is histologically characterized by medial degeneration and various degrees of chronic adventitial inflammation, although the mechanisms for progression of aneurysm are poorly understood. In the present study, we carried out histological study of AAA tissues of patients, and interventional animal and cell culture experiments to investigate a role of mast cells in the pathogenesis of AAA. The number of mast cells was found to increase in the outer media or adventitia of human AAA, showing a positive correlation between the cell number and the AAA diameter. Aneurysmal dilatation of the aorta was seen in the control (+/+) rats following periaortic application of calcium chloride (CaCl
2
) treatment but not in the mast cell–deficient mutant Ws/Ws rats. The AAA formation was accompanied by accumulation of mast cells, T lymphocytes and by activated matrix metalloproteinase 9, reduced elastin levels and augmented angiogenesis in the aortic tissue, but these changes were much less in the Ws/Ws rats than in the controls. Similarly, mast cells were accumulated and activated at the adventitia of aneurysmal aorta in the apolipoprotein E–deficient mice. The pharmacological intervention with the tranilast, an inhibitor of mast cell degranulation, attenuated AAA development in these rodent models. In the cell culture experiment, a mast cell directly augmented matrix metalloproteinase 9 activity produced by the monocyte/macrophage. Collectively, these data suggest that adventitial mast cells play a critical role in the progression of AAA.
Depression as a Risk Factor for the Incidence of First-Ever Stroke in 85-Year-Olds
Authors: Liebetrau Martin , Steen Bertil , Skoog Ingmar
Published: May 2008

Background and Purpose—

Depression may increase the risk for stroke. Few studies have examined whether depression increases the risk for stroke in the very old and among the demented. We examined the relation between depression in 85-year-olds and the 3-year incidence of first-ever stroke.

Methods—

A representative sample of 494 85-year-olds (147 demented, 347 nondemented) in Gothenburg, Sweden, was examined with psychiatric examinations and key informant interviews. Diagnoses of depression and dementia were made according to the Diagnostic and Statistical Manual of Mental Disorders, Third Revision. The sample was followed for 3 years regarding the incidence of stroke. Information on stroke was obtained from the Swedish Hospital Discharge Register, death certificates, self-reports, and key informants. Those with known stroke history at baseline (n=93) were excluded from the incidence study.

Results—

The prevalence of depression at age 85 was 19%. Depression at baseline (hazard ratio, 2.7; 95% CI, 1.5 to 4.7;
P
=0.0006) and systolic blood pressure (hazard ratio, 1.014 per 1 mm Hg; 95% CI, 1.00 to 1.03;
P
=0.019) were related to increased incidence of first-ever stroke during follow-up. Depression increased stroke risk both among demented and nondemented individuals. Among the symptoms of depression, only depressed mood was an independent predictor of incidence first-ever stroke in multivariate analyses. Stroke history at age 85 was not associated with clinical depression.

Conclusions—

Depression and stroke are both common in elderly populations. The finding that depression increases risk for first-ever stroke indicates that detection and treatment of depression may have implications for stroke prevention.
Overexpression of Human S100B Exacerbates Brain Damage and Periinfarct Gliosis After Permanent Focal Ischemia
Authors: Mori Takashi , Tan Jun , Arendash Gary W. , Koyama Naoki , Nojima Yoshiko , Town Terrence
Published: May 2008

Background and Purpose—

We have previously demonstrated that augmented and prolonged activation of astrocytes detrimentally influences both the subacute and chronic phases of cerebral ischemia. Furthermore, we have suggested that the astrocyte-derived protein S100B may be important in these pathogenic events. However, the causal relationship between S100B and exacerbation of brain damage in vivo remains to be elucidated.

Methods—

Using transgenic mice overexpressing human S100B (Tg huS100B mice), we examined whether S100B plays a cardinal role in aggravation of brain damage after permanent middle cerebral artery occlusion (pMCAO).

Results—

Tg huS100B mice had significantly larger infarct volumes and worse neurological deficits at any time point examined after pMCAO as compared with CD-1 background strain-matched control mice. Infarct volumes in Tg huS100B mice were significantly increased from 1 to 3 and 5 days after pMCAO (delayed infarct expansion), whereas those in control mice were not significantly altered. S100, glial fibrillary acidic protein, and Iba1 burdens in the periinfarct area were significantly increased through to 7 days after pMCAO in Tg huS100B mice, whereas those in control mice reached a plateau at 3 days after pMCAO.

Conclusions—

These results provide genetic evidence that overexpression of human S100B acts to exacerbate brain damage and periinfarct reactive gliosis (astrocytosis and microgliosis) during the subacute phase of pMCAO.
Mapping Cerebrovascular Reactivity Using Blood Oxygen Level-Dependent MRI in Patients With Arterial Steno-occlusive Disease
Authors: Mandell Daniel M. , Han Jay S. , Poublanc Julien , Crawley Adrian P. , Stainsby Jeff A. , Fisher Joseph A. , Mikulis David J.
Published: May 2008

Background and Purpose—

Blood oxygen level-dependent MRI (BOLD MRI) of hypercapnia-induced changes in cerebral blood flow is an emerging technique for mapping cerebrovascular reactivity (CVR). BOLD MRI signal reflects cerebral blood flow, but also depends on cerebral blood volume, cerebral metabolic rate, arterial oxygenation, and hematocrit. The purpose of this study was to determine whether, in patients with stenoocclusive disease, the BOLD MRI signal response to hypercapnia is directly related to changes in cerebral blood flow.

Methods—

Thirty-eight patients with steno-occlusive disease underwent mapping of CVR by both BOLD MRI and arterial spin labeling MRI. The latter technique was used as a reference standard for measurement of cerebral blood flow changes.

Results—

Hemispheric CVR measured by BOLD MRI was significantly correlated with that measured by arterial spin labeling MRI for both gray matter (
R
=0.83,
P
<0.0001) and white matter (
R
=0.80,
P
<0.0001). Diagnostic accuracy (area under receiver operating characteristic curve) for BOLD MRI discrimination between normal and abnormal hemispheric CVR was 0.90 (95% CI=0.81 to 0.98;
P
<0.001) for gray matter and 0.82 (95% CI=0.70 to 0.94;
P
<0.001) for white matter. Regions of paradoxical CVR on BOLD MRI had a moderate predictive value (14 of 19 hemispheres) for spatially corresponding paradoxical CVR on arterial spin labeling MRI. Complete absence of paradoxical CVR on BOLD MRI had a high predictive value (31 of 31 hemispheres) for corresponding nonparadoxical CVR on arterial spin labeling MRI.

Conclusions—

Arterial spin labeling MRI confirms that, even in patients with stenoocclusive disease, the BOLD MRI signal response to hypercapnia predominantly reflects changes in cerebral blood flow.
Nascent Aneurysm Formation at the Basilar Terminus Induced by Hemodynamics
Authors: Gao Ling , Hoi Yiemeng , Swartz Daniel D. , Kolega John , Siddiqui Adnan , Meng Hui
Published: May 2008

Background and Purpose—

Hemodynamic insults at arterial bifurcations are hypothesized to play a key role in intracranial aneurysm formation. This study investigates aneurysm-initiating vascular responses at the rabbit basilar terminus subsequent to common carotid artery ligation.

Methods—

Nine adult female New Zealand white rabbits were subjected to sham, unilateral, or bilateral common carotid artery ligation to produce varying degrees of compensatory basilar artery flow increase. Basilar artery flow velocity and geometry were monitored by transcranial Doppler and rotational angiography, respectively, for 12 weeks after surgery. Bifurcation tissues were harvested at 12 weeks and examined histologically. From the histological sections, we quantified the destructive structural changes at the basilar terminus and correlated them with the basilar artery flow rate increase.

Results—

Subsequent to common carotid artery ligation, basilar artery flow rate increased by 105% to 900% at the maximum. All common carotid artery-ligated rabbits presented nascent aneurysm formation characterized by a bulge with thinned media and absent internal elastic lamina near the basilar terminus. We defined a nascent aneurysm index based on a multiplicative combination of the local destructive remodeling lengths measured at the nascent aneurysm. The nascent aneurysm index strongly correlated with the increase in basilar artery flow rate with
R
2
=0.91.

Conclusion—

Without other known predisposition, flow increase alone at the basilar bifurcation can lead to a nascent aneurysm. This nascent aneurysm formation is dose-dependent on basilar artery flow increase.
Pulse Pressure and Mean Arterial Pressure in Relation to Ischemic Stroke Among Patients With Uncontrolled Hypertension in Rural Areas of China
Authors: Zheng Liqiang , Sun Zhaoqing , Li Jue , Zhang Rui , Zhang Xingang , Liu Shuangshuang , Li Jiajin , Xu Changlu , Hu Dayi , Sun Yingxian
Published: May 2008

Background and Purpose—

Information has been sparse on the comparison of pulse pressure (PP) and mean arterial pressure (MAP) in relation to ischemic stroke among patients with uncontrolled hypertension. The present study examined the relation among PP, MAP, and ischemic stroke in uncontrolled hypertensive subjects in China.

Methods—

A total of 6104 uncontrolled hypertensive subjects aged ≥35 years were screened with a stratified cluster multistage sampling scheme in Fuxin county of Liaoning province of China, of which 317 had ischemic stroke.

Results—

After multivariable adjustment for age, gender, and other confounders, individuals with the highest quartile of PP and MAP had ORs for ischemic stroke of 1.479 (95% CI: 1.027 to 2.130) and 2.000 (95% CI: 1.373 to 2.914) with the lowest quartile as the reference. Adjusted ORs for ischemic stroke were 1.306 for MAP and 1.118 for PP with an increment of 1 SD, respectively. Ischemic stroke prediction of PP was annihilated when PP and MAP were entered in a single model. In patients aged <65 years, on a continuous scale using receive operating characteristics curve, ischemic stroke was predicted by PP (
P
=0.001) and MAP (
P
<0.001). The area under the curve of PP (0.570, 95% CI: 0.531 to 0.609) differed from the area under the curve of MAP (0.633, 95% CI: 0.597 to 0.669;
P
<0.05). Among patients aged ≥65 years, presence of ischemic stroke was only predicted by MAP.

Conclusion—

PP and MAP were both associated with ischemic stroke. Ischemic stroke prediction of PP depended on MAP. On a continuous scale, MAP better predicted ischemic stroke than PP did in diagnostic accuracy.
Biodegradability and Aging Studies of Hybrid Biofiber Reinforced Natural Rubber Biocomposites
Authors: Jacob Maya , Thomas Sabu , Varughese K. T.
Published: May 2008

Natural rubber was reinforced with sisal and oil palm fibers and composites were fabricated based on different fiber loading. Chemically modified fibers, namely, mercerized and silanized fibers, were also used to prepare composites. Biodegradation tests were carried out under soil burial
conditions. It was seen that the durability of the composites was greatly dependent on chemical treatment and fiber content. The stability of composites decreased with increased fiber content. Green composites containing chemically treated sisal and oil palm fibers were found to be less resistant
to soil erosion. Aging experiments were also performed. Scanning electron microscopic studies were performed to look into the degree of degradation of the composite specimens after 12 months exposure in soil. Composites containing chemically functionalized biofibers were found to be less prone
to degradation.
Light Emitting Diodes Containing Langmuir-Blodgett Films of Copolymer of a Poly(p-phenylene-vinylene) Derivative and Poly(octaneoxide)
Authors: Olivati Clarissa A. , Péres Laura O. , Wang Shu H. , Giacometti José A. , Oliveira Osvaldo N. , Balogh Débora T.
Published: May 2008

The properties of Langmuir and Langmuir-Blodgett (LB) films from a block copolymer with polyethylene oxide and phenylene-vinylene moieties are reported. The LB films were successfully transferred onto several types of substrates, with sufficient quality to allow for evaporation of a
metallic electrode on top of the LB films to produce polymer light emitting diodes (PLEDs). The photoluminescence and electroluminescence spectra of the LB film and device were similar, featuring an emission at ca. 475 nm, from which we could infer that the emission mechanisms are essentially
the same as in poly(p-phenylene) derivatives. Analogously to other PLEDs the current versus voltage characteristics of the LB-based device could be explained with the Arkhipov model according to which charge transport occurs among localized sites. The implications for nanotechnology of the
level of control that may be achieved with LB devices will also be discussed.
Release of Liposome-Encapsulated Calcein from Liposome Entrapping Gelatin-Carboxymethylcellulose Films: A Presentation of Different Possibilities
Authors: Peptu Catalina , Popa Marcel , Antimisiaris Sophia G.
Published: May 2008

Liposome entrapment in films consisting of gelatin (GEL) or GEL/sodium carboxymethylcellulose (NaCMC) mixtures, as a method to alter drug release kinetics from polymeric films and/or incorporate sensitive bioactive molecules in solid films, was investigated. Bulk or thin complex (liposome
trapping) films were formed by crosslinking (with glutaraldehyde) solutions of GEL or GEL/NaCMC in presence of calcein-encapsulating or rhodamine-labeled liposomes (Rho-Lip). Rho-Lip were observed by confocal microscopy to be homogenously distributed in the films. Calcein release from films
was evaluated for periods up to 25 d, and it was found that several possibilities, concerning the release of the liposome-encapsulated molecule from the films, are offered; (i) Release can be sustained, if large liposomes are entrapped in the films. In this case the liposome-encapsulated molecules
are released from the films only after they have been released from the vesicles, and the release can be controlled by modifying the film composition, the network density and/or the film geometry. (ii) Intact small unilamellar liposomes (SUV) can be released from the polymeric films depending
on their swelling degree. The later can be controlled by modulating the film composition and amount of crosslinker. Film composition also affects the integrity of the film-entrapped liposomes during the crosslinking process, possibly due its effect on the density of the polymeric network of
the film.
Decaarginine-PEG-Artificial Lipid/DNA Complex for Gene Delivery: Nanostructure and Transfection Efficiency
Authors: Furuhata Masahiko , Danev Radostin , Nagayama Kuniaki , Yamada Yoshifumi , Kawakami Hiroko , Toma Kazunori , Hattori Yoshiyuki , Maitani Yoshie
Published: May 2008

Oligoarginine conjugates are highly efficient vectors for the delivery of plasmid DNA into cells. Decaarginine-conjugated lipid (Arg10-PEG-lipid) was synthesized and the effects of Arg10-PEG-lipid concentration at a fixed DNA concentration on transfection efficiency and the structure
of the complexes were studied below and above critical micelle concentration (CMC), and at the lipid nitrogen/DNA phosphate (N/P) ratio corresponding to transfection, respectively. Arg10-PEG-lipid at the concentration below CMC showed stronger interaction with DNA by fluorescence intensity
distribution analysis, and significantly higher luciferase and green fluorescent protein expression than that above CMC. A phase-contrast cryo-transmission electron microscope (cryo-TEM) experiment showed that the morphology of the complexes depended on the N/P ratio. At a low N/P ratio corresponding
to that in transfection at a lipid concentration below CMC, a net-like structure developed in which plasmid DNA was involved. A further increase in the N/P ratio, a large fibrous nanostructure of complexes, was also observed. Without DNA, these structures were not obtained. The cellular uptake
mechanism of complexes using flow cytometry with inhibitors suggested that complexes with two different morphologies showed similar cellular uptake and uptake mechanism, macropinocytosis. Differences in transfection efficiency of the complexes may be explained by a large fibrous nanostructure
inhibiting the cellular internalization of complexes or the release of DNA from macropinosomes into cytoplasm. Arg10-PEG-lipid/DNA complexes formed a favorable nanostructure for gene delivery, depending on the N/P ratio in water.
Current Rectification in a Single Silicon Nanowire p–n Junction
Authors: Rangineni Yaswanth , Qi Cheng , Goncher Gary , Solanki Raj , Langworthy Kurt
Published: May 2008

Diodes within individual silicon nanowires were fabricated by doping them during growth to produce p–n junctions. Electron beam lithography was then employed to contact p- and n-doped ends of these nanowires. The current–voltage (I–V) measurements
showed diode-like characteristics with a typical threshold voltage (Vt) of about 1 V and an ideality factor (n) of about 3.6 in the quasi-neutral region. The reverse bias I–V measurement showed an exponential behavior, indicating tunneling as the current
leakage mechanism.
Size-Controlled Oxidation-Resistant Copper Fine Particles Covered by Biopolymer Nanoskin
Authors: Tomonari Masanori , Ida Kiyonobu , Yamashita Hiromi , Yonezawa Tetsu
Published: May 2008

Size-controlled oxidation-resistant copper fine particles were prepared from insoluble CuO micron-sized particles. The particle sizes were quite uniform and could be varied only by the concentration of the complex reagent from 45 to 175 nm. No template material was needed for size control.
Gelatin was selected as the protective polymer. Addition of protease after formation of copper fine particles decomposed preferentially loop and tail parts of gelatin. The remaining nanoskin gelatin layer, covered on the particle surface, prevents oxidation of copper.
Effect of Nb and Sc Doping on the Phase Transformation of Sol–Gel Processed TiO2 Nanoparticles
Authors: Ahmad A. , Buzby S. , Ni C. , Shah S. Ismat
Published: May 2008

Nb and Sc doped TiO2 nanoparticles were synthesized via sol–gel technique. Dopant concentration of each element was varied from 0.5 to 1.5 atomic%. The effect of metal ion doping and calcination temperatures on anatase to rutile phase transformation has been investigated.
Samples were analyzed by various analytical methods such as X-ray diffraction (XRD), Transmission Electron Microscope (TEM), X-ray Photoelectron Spectroscopy (XPS) and Energy Dispersive X-ray Spectroscopy (EDS). XRD analyses showed that Nb and Sc doped samples calcined at 300 °C and 350
°C, respectively, were crystalline and had an anatase structure. Results showed that anatase was stable up to 700 °C annealing temperature for samples doped with 0.5 atomic% Nb. There was a sharp transition from anatase to rutile phase above 700 °C and complete rutile structure
was obtained at 750 °C. However, the transformation from anatase to rutile was not so sharp in samples doped with 1.0 atomic% and 1.5 atomic% Nb. Results indicated that higher concentration of Nb helps to stabilize the anatase phase. For samples doped with 0.5 atomic% Sc, anatase phase
is stable up to 650 °C. Transformation from anatase to rutile starts at temperature above 650 °C and 100% rutile phase was obtained at 800 °C while for samples doped with 1.0 atomic% and 1.5 atomic% Sc, the complete transformation from anatase to rutile takes place at an even higher
temperature. Results indicate that increasing the calcination time from 0.5 to 2.0 hours at 500 °C does not affect the stability of anatase phase. However, TEM and XRD data showed that the increase in the annealing time leads to an increase in particles size. The rutile to anatase concentration
ratio increased with temperature above the phase transformation temperature. The activation energy for the phase transformation from anatase to rutile for doped and undoped samples was also measured. There was a general rise in the activation energy with increasing dopant concentration.
Surface Alloying of Mg Alloys After Surface Nanocrystallization
Authors: Zhang Ming-Xing , Shi Yi-Nong , Sun Haiqing , Kelly Patrick M.
Published: May 2008

Surface nanocrystallization using a surface mechanical attrition treatment effectively activates the surface of magnesium alloys due to the increase in grain boundary diffusion channels. As a result, the temperature of subsequent surface alloying treatment of pure Mg and AZ91 alloy
can be reduced from 430 °C to 380 °C. Thus, it is possible to combine the surface alloying process with the solution treatment for this type of alloy. After surface alloying, the hardness of the alloyed layer is 3 to 4 times higher than that of the substrate and this may significantly
improve the wear resistance of magnesium alloys.
The Role of Sulphur in the Synthesis of Carbon Nanotubes by Chemical Vapour Deposition at High Temperatures
Authors: Motta M. S. , Moisala A. , Kinloch I. A. , Windle A. H.
Published: May 2008

Sulphur has been recognised as a growth promoter for carbon fibres and carbon nanotubes for over 30 years. Moreover, the Fe-C-S system, in particular, has been extensively studied for more than half a century in the fields of steelmaking and cast iron. In the present work we examine
the role of sulphur in the iron-catalysed growth of carbon nanotubes during the process of direct spinning of fibres from the gas phase. A detailed microstructural characterisation of the reaction products was conducted by high resolution TEM and EELS composition mapping on a dedicated FEG
STEM (VG HB 501) equipped with Cs aberration correctors. Our results agree with previous works in classical metallurgy, indicating that sulphur forms a layer on the surface of the catalyst particles that plays a role in encouraging nanotube growth by surface diffusion.
Cell-Type Specific and Cytoplasmic Targeting of PEGylated Carbon Nanotube-Based Nanoassemblies
Authors: Cato Matthew H. , D'Annibale Federica , Mills David M. , Cerignoli Fabio , Dawson Marcia I. , Bergamaschi Enrico , Bottini Nunzio , Magrini Andrea , Bergamaschi Antonio , Rosato Nicola , Rickert Robert C. , Mustelin Tomas , Bottini Massimo
Published: May 2008

In this paper we report the fabrication of a multivalent, cell-type specific and cytoplasmic delivery system based on single-walled carbon nanotubes. The latter were functionalized through adsorption of phospholipids terminated by biotinylated PEG chains functionalized with fluorochrome-coupled
neutravidin, and subsequently with antibodies (anti-CD3ε and anti-CD28) for T cell receptor post-signaling endocytosis and a synthetic fusogenic polymer for disruption of lysosomal compartments. The biomimetic nanoassemblies were composed by PEGylated individual/very small bundles
of carbon nanotubes having an average length and a standard deviation of 176 nm and 77 nm, respectively. The nanoassemblies were stably dispersed under physiological conditions, visible by conventional optical and confocal microscopy and specifically targeted to T cells both in vitro
and in living animals. The addition of a fusogenic polymer to the nanoassemblies did not affect the cellular uptake and allowed the release into the cytosol of the targeted cells both in vitro and in the animals. The present manuscript is the first report about the cytoplasmic delivery
of carbon nanotubes in a specific cell type in intact animals and paves the way for their use as in vivo intracellular delivery systems.
Prediction of Nanofiber Diameter and Optimization of Electrospinning Process via Response Surface Methodology
Authors: Naderi Nader , Agend Farima , Faridi-Majidi Reza , Sharifi-Sanjani Naser , Madani Mohammad
Published: May 2008

Response surface methodology (RSM) was used to obtain a more systematic understanding of the electrospinning conditions of polyamide 6 solutions. This method was used to establish a quantitative basis for the relationships between the electrospinning parameters such as applied electric
field, the polymer concentrations, the rate of injection and nozzle-collector distance with the diameter of the produced nanofibers, and to predict the optimum conditions for electrospinning to produce nanofibers with controlled size. A response function was empirically determined by central
composite design (CCD) using fiber diameter as an observed response and the electrospinning parameters as variables. The relationship between the response and the variables is visualized by a response surface or contour plots. The study of the graphical representations of contour plots, prediction
formulas and prediction profiler can predict the operating conditions necessary to generate nanofibers with the desired diameters.
Comparison Between Poly(methyl methacrylate)-Carbon Black and Polyaniline Conductive Coatings
Authors: Li L. , Liu E. , Goh L. Z. , Lee Y. P.
Published: May 2008

This work aims to develop and compare two types of conductive, polymer-based coatings via a dip coating process. The first type of coatings was made by dispersing and incorporating carbon black (CB) nanoparticles in a poly(methyl methacrylate) (PMMA) solution followed by dip coating.
The CB content and dipping parameters were varied to explore their effects on the particle dispersion, coating thickness, and conductivity of the coatings. The dispersion of the CB particles in the polymer matrix was examined by scanning electron microscopy (SEM), while the coating thickness
and conductivity were measured with a surface profilometer and a four-point probe electrometer, respectively. The good dispersion of carbon nanoparticles in the PMMA matrix was observed in the coatings. The conductivity of the PMMA-CB composite coatings was found to be mainly affected by CB
content, particle dispersion as well as coating thickness. On the other hand, polyaniline (PANI) was used to make conductive coatings by dip coating and doping, and the advantages and limitations of the PANI coatings were compared with the PMMA-CB coatings.
Direct Alpha Ta Formation on TaN by Resputtering for Low Resistive Diffusion Barriers
Authors: Tsao Jung-Chih , Liu Chuan-Pu , Wang Ying-Lang , Chen Kei-Wei
Published: May 2008

The Ta/TaN bilayer exhibits the best performance in the Cu metal multilevel interconnects, because it provides good coherence between Cu and dielectric layer. In the Ta/TaN bilayer, Ta has two phases: alpha-phase of body center cubic is preferred due to its lower resistivity (15–60
μΩ-cm), whereas beta-phase of tetragonal should be avoided due to high resistive (∼150–250 μΩ-cm). However, beta Ta most commonly forms on fcc TaN. Here we provide a simple scheme to bypass this high resistive phase by resputtering TaN prior to Ta
deposition. We found that, with surface treatment by argon ion bombardment for enough time, alpha Ta phase can be directly formed, which is supported both by X-ray diffraction and resistivity measurement. Depth profiles of all elements from Auger electron spectroscopy reveals that the surface
treatment induces a nitrogen deficient surface layer due to different sputtering yield, which causes phase changes from fcc TaN to hcp Ta2N followed by bcc Ta(N) and provide a favorable lattice constant for Ta alpha-phase formation.
The Effects of Oxygen Content on Bonding Configurations and Properties of Low-k Organosilicate Glass Dielectric Films
Authors: Chen Sheng-Wen , Liu Chuan-Pu , Jangjian Shiu-Ko , Wang Ying-Lang
Published: May 2008

The low dielectric constant SiOC:H films of plasma enhanced chemical vapor deposition method have been developed with various precursor ratio. The reduction of the dielectric constant has been achieved by increasing the porosity in the films through the change of precursor ratio. In
order to clarify the relation between dielectric constant and film porosity, the small angle X-ray scattering technique has been applied for characterizing pore size in the porous low-k dielectric films. The effects of the oxygen on the bonding configuration and electrical properties
were investigated by adjusting TMS/O2 gas ratios. The porous SiOC:H film displays the small pore sizes and lower dielectric constant. It is found that the pore size of SiOC:H film is significant smaller than 1 nm and the pore size attributed to Si–O–Si cage structure
change.
Piezoelectrics in Micro and Nanosystems: Solutions for a Wide Range of Applications
Authors: Muralt Paul
Published: May 2008

Piezoelectric thin films have interesting prospects in a number of applications for which miniaturization is a driving force. Miniaturization means higher frequency, or higher resolution, or increased functionality. This paper gives a short review on piezoelectric thin films, their
deposition processes, integration, properties and applications in microsystems (MEMS), concentrating on the most frequently investigated piezoelectric thin film materials.
Limitations of Bispectral Infrared Cloud Phase Determination and Potential for Improvement
Authors: Nasiri Shaima L. , Kahn Brian H.
Published: May 2008

Determining cloud thermodynamic phase using infrared satellite observations typically requires a priori assumptions about relationships between cloud phase and cloud temperature. In this study, limitations of an approach using two infrared channels with moderate spectral resolutions are demonstrated, as well as the potential for improvement using channels with higher spectral resolution. The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument uses a bispectral infrared cloud phase determination algorithm. MODIS observations during January 2005 show that approximately 23% of cloudy pixels are classified as mixed or unknown cloud phase; this increases to 78% when only cloud-top temperatures between 250 and 265 K are considered. Radiative transfer simulations show that the bispectral algorithm has limited ability to discriminate between water and ice clouds in this temperature range. There is also the potential for thin ice clouds at colder temperatures to be misclassified as water clouds. In addition, sensitivities to cloud particle size and cloud height can be larger than sensitivities to cloud phase. Simulations suggest that phase sensitivity may be higher with hyperspectral observations such as those from the Atmospheric Infrared Sounder (AIRS). The AIRS brightness temperature differences between channels at 8.1 and 10.4 μm show phase sensitivities of at least 0.5 K, regardless of cloud particle size, cloud-top temperature, or cloud height. They also demonstrate reduced sensitivity to atmospheric temperature and water vapor variability. The reduced sensitivity of AIRS radiances to these physical quantities shows that hyperspectral sounders will serve an important role in refining estimates of cloud phase.