bluuebunny/crossref_metadata_2025 huggingface dataset:
Two Protein Lysine Methyltransferases Methylate Outer Membrane Protein B from Rickettsia
Authors: Abeykoon Amila H. , Chao Chien-Chung , Wang Guanghui , Gucek Marjan , Yang David C. H. , Ching Wei-Mei
Published: September 2012

Rickettsia prowazekii
, the etiologic agent of epidemic typhus, is a potential biological threat agent. Its outer membrane protein B (OmpB) is an immunodominant antigen and plays roles as protective envelope and as adhesins. The observation of the correlation between methylation of lysine residues in rickettsial OmpB and bacterial virulence has suggested the importance of an enzymatic system for the methylation of OmpB. However, no rickettsial lysine methyltransferase has been characterized. Bioinformatic analysis of genomic DNA sequences of
Rickettsia
identified putative lysine methyltransferases. The genes of the potential methyltransferases were synthesized, cloned, and expressed in
Escherichia coli
, and expressed proteins were purified by nickel-nitrilotriacetic acid (Ni-NTA) affinity chromatography. The methyltransferase activities of the purified proteins were analyzed by methyl incorporation of radioactively labeled
S
-adenosylmethionine into recombinant fragments of OmpB. Two putative recombinant methyltransferases (rRP789 and rRP027-028) methylated recombinant OmpB fragments. The specific activity of rRP789 is 10- to 30-fold higher than that of rRP027-028. Western blot analysis using specific antibodies against trimethyl lysine showed that both rRP789 and rRP027-028 catalyzed trimethylation of recombinant OmpB fragments. Liquid chromatography-tandem mass spectrometry (LC/MS-MS) analysis showed that rRP789 catalyzed mono-, di-, and trimethylation of lysine, while rRP027-028 catalyzed exclusively trimethylation. To our knowledge, rRP789 and rRP027-028 are the first biochemically characterized lysine methyltransferases of outer membrane proteins from Gram-negative bacteria. The production and characterization of rickettsial lysine methyltransferases provide new tools to investigate the mechanism of methylation of OmpB, effects of methylation on the structure and function of OmpB, and development of methylated OmpB-based diagnostic assays and vaccine candidates.
Cold Shock Genes
cspA
and
cspB
from Caulobacter crescentus Are Posttranscriptionally Regulated and Important for Cold Adaptation
Authors: Mazzon Ricardo R. , Lang Elza A. S. , Silva Carolina A. P. T. , Marques Marilis V.
Published: September 2012

Cold shock proteins (CSPs) are nucleic acid binding chaperones, first described as being induced to solve the problem of mRNA stabilization after temperature downshift.
Caulobacter crescentus
has four CSPs: CspA and CspB, which are cold induced, and CspC and CspD, which are induced only in stationary phase. In this work we have determined that the synthesis of both CspA and CspB reaches the maximum levels early in the acclimation phase. The deletion of
cspA
causes a decrease in growth at low temperature, whereas the strain with a deletion of
cspB
has a very subtle and transient cold-related growth phenotype. The
cspA cspB
double mutant has a slightly more severe phenotype than that of the
cspA
mutant, suggesting that although CspA may be more important to cold adaptation than CspB, both proteins have a role in this process. Gene expression analyses were carried out using
cspA
and
cspB
regulatory fusions to the
lacZ
reporter gene and showed that both genes are regulated at the transcriptional and posttranscriptional levels. Deletion mapping of the long 5′-untranslated region (5′-UTR) of each gene identified a common region important for cold induction, probably via translation enhancement. In contrast to what was reported for other bacteria, these cold shock genes have no regulatory regions downstream from ATG that are important for cold induction. This work shows that the importance of CspA and CspB to
C. crescentus
cold adaptation, mechanisms of regulation, and pattern of expression during the acclimation phase apparently differs in many aspects from what has been described so far for other bacteria.
Dynamic Localization of Tat Protein Transport Machinery Components in Streptomyces coelicolor
Authors: Willemse Joost , Ruban-Ośmialowska Beata , Widdick David , Celler Katherine , Hutchings Matthew I. , van Wezel Gilles P. , Palmer Tracy
Published: September 2012

The Tat pathway transports folded proteins across the bacterial cytoplasmic membrane and is a major route of protein export in theStreptomycesgenus of bacteria. In this study, we have examined the localization of Tat components in the model organismStreptomyces coelicolorby constructing enhanced green fluorescent protein (eGFP) and mCherry fusions with the TatA, TatB, and TatC proteins. All three components colocalized dynamically in the vegetative hyphae, with foci of each tagged protein being prominent at the tips of emerging germ tubes and of the vegetative hyphae, suggesting that this may be a primary site of Tat secretion. Time-lapse imaging revealed that localization of the Tat components was highly dynamic during tip growth and again demonstrated a strong preference for apical sites in growing hyphae. During aerial hypha formation, TatA-eGFP and TatB-eGFP fusions relocalized to prespore compartments, indicating repositioning of Tat components during theStreptomyceslife cycle.
The Structure of the PapD-PapGII Pilin Complex Reveals an Open and Flexible P5 Pocket
Authors: Ford Bradley , Verger Denis , Dodson Karen , Volkan Ender , Kostakioti Maria , Elam Jennifer , Pinkner Jerome , Waksman Gabriel , Hultgren Scott
Published: September 2012

P pili are hairlike polymeric structures that mediate binding of uropathogenic
Escherichia coli
to the surface of the kidney via the PapG adhesin at their tips. PapG is composed of two domains: a lectin domain at the tip of the pilus followed by a pilin domain that comprises the initial polymerizing subunit of the 1,000-plus-subunit heteropolymeric pilus fiber. Prior to assembly, periplasmic pilin domains bind to a chaperone, PapD. PapD mediates donor strand complementation, in which a beta strand of PapD temporarily completes the pilin domain's fold, preventing premature, nonproductive interactions with other pilin subunits and facilitating subunit folding. Chaperone-subunit complexes are delivered to the outer membrane usher where donor strand exchange (DSE) replaces PapD's donated beta strand with an amino-terminal extension on the next incoming pilin subunit. This occurs via a zip-in–zip-out mechanism that initiates at a relatively accessible hydrophobic space termed the P5 pocket on the terminally incorporated pilus subunit. Here, we solve the structure of PapD in complex with the pilin domain of isoform II of PapG (PapGIIp). Our data revealed that PapGIIp adopts an immunoglobulin fold with a missing seventh strand, complemented in parallel by the G1 PapD strand, typical of pilin subunits. Comparisons with other chaperone-pilin complexes indicated that the interactive surfaces are highly conserved. Interestingly, the PapGIIp P5 pocket was in an open conformation, which, as molecular dynamics simulations revealed, switches between an open and a closed conformation due to the flexibility of the surrounding loops. Our study reveals the structural details of the DSE mechanism.
Conserved Region 3 of Human Papillomavirus 16 E7 Contributes to Deregulation of the Retinoblastoma Tumor Suppressor
Authors: Todorovic Biljana , Hung Katherine , Massimi Paola , Avvakumov Nikita , Dick Frederick A. , Shaw Gary S. , Banks Lawrence , Mymryk Joe S.
Published: September 2012

The human papillomavirus (HPV) E7 oncoprotein binds cellular factors, preventing or retargeting their function and thereby making the infected cell conducive for viral replication. A key target of E7 is the product of the retinoblastoma susceptibility locus (pRb). This interaction results in the release of E2F transcription factors and drives the host cell into the S phase of the cell cycle. E7 binds pRb via a high-affinity binding site in conserved region 2 (CR2) and also targets a portion of cellular pRb for degradation via the proteasome. Evidence suggests that a secondary binding site exists in CR3, and that this interaction influences pRb deregulation. Additionally, evidence suggests that CR3 also participates in the degradation of pRb. We have systematically analyzed the molecular mechanisms by which CR3 contributes to deregulation of the pRb pathway by utilizing a comprehensive series of mutations in residues predicted to be exposed on the surface of HPV16 E7 CR3. Despite differences in the ability to interact with cullin 2, all CR3 mutants degrade pRb comparably to wild-type E7. We identified two specific patches of residues on the surface of CR3 that contribute to pRb binding independently of the high-affinity CR2 binding site. Mutants within CR3 that affect pRb binding are less effective than the wild-type E7 in overcoming pRb-induced cell cycle arrest. This demonstrates that the interaction between HPV16 E7 CR3 and pRb is functionally important for alteration of the cell cycle.
Mouse Mammary Tumor Virus Suppresses Apoptosis of Mammary Epithelial Cells through ITAM-Mediated Signaling
Authors: Kim Hyoung H. , Grande Shannon M. , Monroe John G. , Ross Susan R.
Published: September 2012

Many receptors in hematopoietic cells use a common signaling pathway that relies on a highly conserved immunoreceptor tyrosine-based activation motif (ITAM), which signals through Src family tyrosine kinases. ITAM-bearing proteins are also found in many oncogenic viruses, including the mouse mammary tumor virus (MMTV) envelope (Env). We previously showed that MMTV Env expression transformed normal mammary epithelial cells and that Src kinases were important mediators in this transformation. To study how ITAM signaling affects mammary cell transformation, we utilized mammary cell lines expressing two different ITAM-containing proteins, one encoding a MMTV provirus and the other a B cell receptor fusion protein. ITAM-expressing cells were resistant to both serum starvation- and chemotherapeutic drug-induced apoptosis, whereas cells transduced with these molecules bearing ITAM mutations were indistinguishable from untransduced cells in their sensitivity to these treatments. We also found that Src kinase was activated in the MMTV-expressing cells and that MMTV-induced apoptosis resistance was completely restored by the Src inhibitor PP2.
In vivo
, MMTV infection delayed involution-induced apoptosis in the mouse mammary gland. Our results show that MMTV suppresses apoptosis through ITAM-mediated Src tyrosine kinase signaling. These studies could lead to the development of effective treatment of nonhematopoietic cell cancers in which ITAM-mediated signaling plays a role.
A Meta-Analysis of the Efficacy of Acupuncture in Treating Dysphagia in Patients with a Stroke
Authors: Long Yao-Bin , Wu Xiao-Ping
Published: September 2012

Background

Dysphagia, or deglutition difficulty, is a common manifestation in patients with a stroke and its management is an important aspect of rehabilitation. Acupuncture, a complementary and alternative therapy, is the subject of growing public interest for treatment of stroke.

Objective

A meta-analysis was performed to study the effect of acupuncture for treatment of dysphagia in patients affected by a stroke.

Methods

Randomised controlled trials (RCTs) comparing acupuncture treatment with non-acupuncture treatment of dysphagia in patients with a stroke were identified from the databases of PubMed, Embase, Cochrane Library and CBM disc (China Biological Medicine Database). Eligible investigations were included and data on the effectiveness of acupuncture were extracted and synthesised by meta-analysis using RevMan 5.1.4. Results were expressed as OR for dichotomous data; 95% CIs were also calculated.

Results

Seventy-two RCTs (3208 patients in the treatment group and 2926 patients in the control group) were identified. Details of randomisation and blinding were not reported and information on withdrawals and dropouts was missing in most of included reports. Meta-analysis showed that the effectiveness of treatment in the group receiving acupuncture was higher than that in the non-acupuncture group (OR=5.17, 95% CI 4.18 to 6.38; p<0.00001). However, the study quality was generally low and of insufficient quality to make recommendations about using acupuncture in the rehabilitation of patients with dysphagia due to stroke.

Conclusions

Acupuncture might be beneficial in the rehabilitation of patients with dysphagia caused by stroke, and the evidence justifies future high-quality studies.
Effectiveness of telemedicine and distance learning applications for patients with chronic heart failure. A protocol for prospective parallel group non-randomised open label study
Authors: Vanagas Giedrius , Umbrasienė Jelena , Šlapikas Rimvydas ,   ICT for Health project workgroup
Published: September 2012

Introduction

Chronic heart failure in Baltic Sea Region is responsible for more hospitalisations than all forms of cancer combined and is one of the leading causes of hospitalisations in elderly patients. Frequent hospitalisations, along with other direct and indirect costs, place financial burden on healthcare systems. We aim to test the hypothesis that telemedicine and distance learning applications is superior to the current standard of home care.

Methods and analysis

Prospective parallel group non-randomised open label study in patients with New York Heart Association (NYHA) II–III chronic heart failure will be carried out in six Baltic Sea Region countries. The study is organised into two 6-month follow-up periods. The first 6-month period is based on active implementation of tele-education and/or telemedicine for patients in two groups (active run period) and one standard care group (passive run period). The second 6-month period of observation will be based on standard care model (passive run period) to all three groups. Our proposed practice change is based on translational research with empirically supported interventions brought to practice and aims to find the home care model that is most effective to patient needs.

Ethics and dissemination

This study has been approved by National Bioethics Committee (2011-03-07; Registration No: BE-2-11).

Trial Registration

This study has been registered in Australian New Zealand Clinical Trials Registry (ANZCTR) with registration number ACTRN12611000834954.
Preventing renal and cardiovascular risk by renal function assessment: insights from a cross-sectional study in low-income countries and the USA
Authors: Cravedi Paolo , Sharma Sanjib Kumar , Bravo Rodolfo Flores , Islam Nazmul , Tchokhonelidze Irma , Ghimire Madhav , Pahari Bishnu , Thapa Sanjeev , Basnet Anil , Tataradze Avtandil , Tinatin Davitaia , Beglarishvili Lela , Fwu Chyng-Wen , Kopp Jeffrey B , Eggers Paul , Ene-Iordache Bogdan , Carminati Sergio , Perna Annalisa , Chianca Antonietta , Couser William G , Remuzzi Giuseppe , Perico Norberto
Published: September 2012

Objective

To assess the prevalence of microalbuminuria and kidney dysfunction in low-income countries and in the USA.

Design

Cross-sectional study of screening programmes in five countries.

Setting

Screening programmes in Nepal, Bolivia, the USA (National Health and Nutrition Examination Survey (NHANES) 2005–2008) Bangladesh and Georgia.

Participants

General population in Nepal (n=20 811), Bolivia (n=3436) and in the USA (n=4299) and high-risk subjects in Bangladesh (n=1518) and Georgia (n=1549).

Primary and secondary outcome measures

Estimated glomerular filtration rate (eGFR)<60ml/min/1.73 m2and microalbuminuria (defined as urinary albumin creatinine ratio values of 30–300 mg/g) were the main outcome measures. The cardiovascular (CV) risk was also evaluated on the basis of demographic, clinical and blood data.

Results

The prevalence of eGFR<60ml/min/1.73 m2was 19%, 3.2% and 7% in Nepal, Bolivia and the USA, respectively. In Nepal, 7% of subjects were microalbuminuric compared to 8.6% in the USA. The prevalence of participants with predicted 10-year CV disease (CVD) risk ≥10% was 16.9%, 9.4% and 17% in Nepal, Bolivia and in the USA, respectively. In Bangladesh and Georgia, subjects with eGFR<60 ml/min/1.73 m2were 8.6% and 4.9%, whereas those with microalbuminuria were 45.4% and 56.5%, respectively. Predicted 10-year CVD risk ≥10% was 25.4% and 25% in Bangladesh and Georgia, respectively.

Conclusions

Renal abnormalities are common among low-income countries and in the USA. Prevention programmes, particularly focused on those with renal abnormalities, should be established worldwide to prevent CVD and progression to end-stage renal disease.
Anabolic steroids in patients undergoing total knee arthroplasty
Authors: Metcalfe David , Watts Evan , Masters James P , Smith Neil
Published: September 2012

Objectives

To systematically review the evidence for using anabolic-androgenic steroids (AAS) to aid rehabilitation following total knee replacement (TKR).

Design

Systematic review of all clinical study designs.

Data sources

MEDLINE, EMBASE, AMED, CINAHL and the Cochrane Library were searched from inception to August 2012.

Eligibility criteria

All clinical study designs without language or patient demographic limits.

Outcome measures

All functional, physiological and administrative outcomes as well as reporting of adverse events.

Results

Only two small randomised controlled trials satisfied the inclusion criteria. Statistically significant improvements were reported in the AAS group for quadriceps strength at 3 (p=0.02), 6 (p=0.01) and 12 (p=0.02) months, Functional Independence Measure score at 35 days (p=<0.05) and Knee Society Score at 6 weeks (p=0.02), 6 months (p=0.04) and 12 months (p=0.03). However, differences in hamstring strength, bone mineral density, sit-to-stand testing, walking speed, length of hospital stay and need for further inpatient rehabilitation did not reach statistical significance. There were no reported adverse events.

Conclusions

There is insufficient evidence to recommend routine administration of AAS to patients undergoing TKR. However, pilot data suggest that AAS can be administered safely and may improve important postoperative outcome measures. This justifies a randomised trial sufficiently powered to identify between-group differences likely to be of clinical significance.
Influence ofFCGR3Agenotype on the therapeutic response to rituximab in rheumatoid arthritis: an observational cohort study
Authors: Kastbom Alf , Cöster Lars , Ärlestig Lisbeth , Chatzidionysiou Aikaterini , van Vollenhoven Ronald F , Padyukov Leonid , Rantapää-Dahlqvist Solbritt , Saevarsdottir Saedis
Published: September 2012

Objectives

To determine whether a polymorphism in the Fcγ receptor type IIIA (FCGR3A-F158V), influencing immunoglobulin G binding affinity, relates to the therapeutic efficacy of rituximab in rheumatoid arthritis (RA) patients.

Design

Observational cohort study.

Setting

Three university hospital rheumatology units in Sweden.

Participants

Patients with established RA (n=177; 145 females and 32 males) who started rituximab (Mabthera) as part of routine care.

Primary outcome measures

Response to rituximab therapy in relation to FCGR3A genotype, including stratification for sex.

Results

The frequency of responders differed significantly acrossFCGR3Agenotypes (p=0.017 in a 3×2 contingency table). Heterozygous patients showed the highest response rate at 83%, as compared with patients carrying 158FF (68%) or 158VV (56%) (p=0.028 and 0.016, respectively). Among 158VV patients, response rates differed between male and female patients (p=0.036), but not among 158FF or 158VF patients (p=0.72 and 0.46, respectively).

Conclusions

Therapeutic efficacy of rituximab in RA patients is influenced byFCGR3Agenotype, with the highest response rates found among heterozygous patients. This may suggest that different rituximab mechanisms of action in RA are optimally balanced inFCGR3A-158VF patients. Similar to the previously described associations with RA susceptibility and disease course, the impact of 158VV on rituximab response may be influenced by sex.
Hyponatraemia in patients with crush syndrome during the Wenchuan earthquake
Authors: Zhang Li , Fu Ping , Wang Li , Cai Guangyan , Zhang Lin , Chen Dezheng , Guo Dongyang , Sun Xuefeng , Chen Fuqiong , Bi Weihong , Zeng Xinjie , Li Haiyan , Liu Zhaohui , Wang Yong , Huang Songmin , Chen Xiangmei ,   for the Wenchuan earthquake-related AKI study group
Published: September 2012

Background

Although sodium disturbances are common in hospitalised patients, no study has specifically investigated the epidemiology of hyponatraemia in patients with crush syndrome.

Objectives

To describe the incidence of hyponatraemia and assess its effect on outcome in patients with crush syndrome during the Wenchuan earthquake.

Methods

A retrospective study was conducted in 17 reference hospitals during the Wenchuan earthquake. We excluded patients younger than 15 years and those with missing sodium values within 3 days after being rescued from the ruins.

Results

Hyponatraemia (serum sodium concentration <135 mmol/l) was seen in 91/180 (50.6%) patients on admission. Compared with patients with normonatraemia, those with hyponatraemia were younger, had more severe traumatic injury and renal failure, underwent more fasciotomies, received more blood transfusion and renal replacement therapy. In the multivariable-adjusted model, the number of extremity injuries (OR=1.59, 95% CI 1.08 to 2.33) and serum creatinine (OR=1.30, 95% CI 1.07 to 1.59) were independently associated with the occurrence of hyponatraemia. Covariate adjusted multiple logistic regression analysis showed an independent mortality risk rising with hyponatraemia (OR=5.74, 95% CI 1.18 to 28.00).

Conclusions

Hyponatraemia was common in the patients with crush syndrome during the Wenchuan earthquake and associated with poor prognosis. Water, commercial drinks and hypotonic intravenous fluids should be supplied carefully to patients with crush syndrome.
Managing demand for laboratory tests: a laboratory toolkit
Authors: Fryer Anthony A , Smellie W Stuart A
Published: September 2012

Healthcare budgets worldwide are facing increasing pressure to reduce costs and improve efficiency, while maintaining quality. Laboratory testing has not escaped this pressure, particularly since pathology investigations cost the National Health Service £2.5 billion per year. Indeed, the Carter Review, a UK Department of Health-commissioned review of pathology services in England, estimated that 20% of this could be saved by improving pathology services, despite an average annual increase of 8%–10% in workload. One area of increasing importance is managing the demands for pathology tests and reducing inappropriate requesting. The Carter Review estimated that 25% of pathology tests were unnecessary, representing a huge potential waste. Certainly, the large variability in levels of requesting between general practitioners suggests that inappropriate requesting is widespread. Unlocking the key to this variation and implementing measures to reduce inappropriate requesting would have major implications for patients and healthcare resources alike. This article reviews the approaches to demand management. Specifically, it aims to (a) define demand management and inappropriate requesting, (b) assess the drivers for demand management, (c) examine the various approaches used, illustrating the potential of electronic requesting and (d) provide a wider context. It will cover issues, such as educational approaches, information technology opportunities and challenges, vetting, duplicate request identification and management, the role of key performance indicators, profile composition and assessment of downstream impact of inappropriate requesting. Currently, many laboratories are exploring demand management using a plethora of disparate approaches. Hence, this review seeks to provide a ‘toolkit’ with the view to allowing laboratories to develop a standardised demand management strategy.
Myocardial cell sheet therapy and cardiac function
Authors: Fujita Jun , Itabashi Yuji , Seki Tomohisa , Tohyama Shugo , Tamura Yuichi , Sano Motoaki , Fukuda Keiichi
Published: September 2012

Heart failure (HF) is the leading cause of death in developed countries. Regenerative medicine has the potential to drastically improve treatment for advanced HF. Stem cell-based medicine has received attention as a promising candidate therapy over the past decade; however, it has not yet realized this potential in terms of reliability. The cell sheet is an innovative technology for constructing aligned graft cells, and several cell sources have been investigated for making a feasible cell sheet. The most representative thus far is skeletal myoblast, although such cells raise the issue of arrhythmogenicity. Regenerative cardiomyocytes (CMs) derived from pluripotent stem cells (PSCs), such as embryonic stem cells or induced PSCs, are the most promising, because a myocardial cell sheet (MCS) constructed with regenerative CMs can potentially enable contraction recovery and electromechanical coupling with host CMs. The functional outcomes of experimental MCS are reduction of ventricular wall stress and paracrine effects rather than contraction recovery. Several technical obstacles still hamper the clinical application of MCSs, with graft survival the most pivotal issue. Ischemia, apoptosis, inflammation, and immune response can all cause graft cell death, and a stable blood supply to the MCS is critical for successful engraftment. Ventricular tachycardia must also be considered in any myocardial cell therapy, and multiple layering of MCS (>3 layers) is necessary to reconstruct human myocardium. Innervation is also a potential issue. The future application of myocardial cell therapy with MCS for advanced HF depends on resolving these difficulties.
Comparison between adenosine and isoflurane for assessing the coronary flow reserve in mouse models of left ventricular pressure and volume overload
Authors: You Jieyun , Wu Jian , Ge Junbo , Zou Yunzeng
Published: September 2012

Adenosine and high-concentration isoflurane are commonly used to induce hyperemia for assessment of coronary flow reserve (CFR) in mice, but high-concentration isoflurane may exacerbate cardiac dysfunction, leading to impaired CFR. However, there is no study be found comparing the effects of adenosine and isoflurane on CFR and corresponding cardiac function. High-resolution echocardiography and invasive hemodynamic assessment were performed in 20 mice 2 wk after transverse aortic constriction (TAC), aortic regurgitation (AR), and corresponding sham operation. CFR was calculated as the ratio of hyperemic to basal peak diastolic velocity (CFRpdv) or diastolic velocity-time integral (CFRdvti). In the sham-operated mice, no differences were observed between the effects of adenosine and isoflurane on CFR, left ventricular systolic function (left ventricular ejection fraction and fractional shortening), left ventricular end-systolic pressure, maximal contraction and relaxation velocity (+dp/d t and −dp/d t), alteration of left ventricular pressure (ΔLVP), or ± dp/d t (Δdp/d t). But adenosine-derived results were significantly higher than isoflurane-derived ones in both the TAC and the AR groups. Moreover, CFRpdv or CFRdvti was positively correlated with both LVEF and LVFS. Compared with adenosine-derived CFR, isoflurane-derived CFR may be underestimated in the TAC and the AR mice, which is probably associated with suppressed cardiac function.
Progression of myocardial remodeling and mechanical dysfunction in the spontaneously hypertensive rat
Authors: LeGrice Ian J. , Pope Adèle J. , Sands Gregory B. , Whalley Gillian , Doughty Robert N. , Smaill Bruce H.
Published: September 2012

The progression of hypertensive heart disease (HHD) to heart failure (HF) is associated with myocardial remodeling. Corresponding changes in three-dimensional organization of cardiac extracellular matrix have not been quantified or related fully to the development of HF. Spontaneously hypertensive rats (SHRs) and Wistar-Kyoto controls were studied at 3, 12, 18, and 24 mo. Hemodynamic and morphological data, brain natriuretic peptide levels, and echocardiography demonstrate four distinct disease stages: systemic hypertension, diastolic dysfunction, early systolic failure, and decompensated HF. Passive left ventricular (LV) pressure-volume relationships were determined in vitro. Transmural specimens from the anterior LV free wall were imaged using extended-volume confocal microscopy, and three-dimensional myocardial architecture was quantified. In SHRs, LV compliance was reduced at 12 mo and increased progressively thereafter. However, it was less than in controls for filling pressures <10 mmHg and not significantly different at ≥10 mmHg. Myocyte cross section was enlarged, with increased variability from 12 mo, while collagen fraction increased progressively. Perimysial collagen fraction remained unchanged with age, although endomysial collagen increased from 12 mo. Perimysial collagen between adjacent muscle layers fused at 12 mo and continued to thicken subsequently, while muscle layers became more dispersed and disordered. We conclude that LV dilatation, which accompanies decompensated HF in this model of HHD, is not due to LV “softening.” While perimysial (and endomysial) collagen networks are substantially remodeled, they are not dissolved, as has been proposed. We argue that progressive disruption of the laminar organization of LV myocardium may contribute to impaired systolic function in HHD.
Postprandial heat production in skeletal muscle is associated with altered mitochondrial function and altered futile calcium cycling
Authors: Clarke Scott D. , Lee Kevin , Andrews Zane B. , Bischof Robert , Fahri Fahri , Evans Roger G. , Clarke Iain J. , Henry Belinda A.
Published: September 2012

This study aimed to determine whether postprandial temperature excursions in skeletal muscle are consistent with thermogenesis or altered blood flow. Temperature probes were implanted into the vastus lateralis muscle of ovariectomized ewes, and blood flow was assessed using laser-Doppler flowmetry (tissue flow) and transit-time ultrasound flowmetry (femoral artery flow). The animals were program-fed between 1100 and 1600, and temperature and blood flow were measured during intravenous administration of either isoprenaline or phenylephrine and during feeding and meal anticipation. In addition, muscle biopsies were collected prefeeding and postfeeding to measure uncoupling protein (UCP) expression and mitochondrial function, as well as indices of calcium cycling (ryanodine 1 receptor: RyR1 and sarcoendoplasmic calcium-dependent ATPases SERCA1/ SERCA2a). Isoprenaline increased femoral artery blood flow, whereas phenylephrine reduced blood flow. At high doses only, isoprenaline treatment increased heat production in muscle. Phenylephrine treatment did not alter muscle temperature. Meal anticipation was evoked in fasted animals (previously program-fed) that were housed beside animals that were fed. Increases in muscle temperature were elicited by feeding and meal anticipation, without changes in blood flow during either paradigm. Analyses of respiration in isolated mitochondria indicated that the postprandial increase in heat production was associated with an increase in state 4 respiration, without increased UCP1, UCP2, or UCP3 expression. Feeding increased the expression of RyR1 and SERCA2a. We conclude that excursions in muscle temperature may occur independent of blood flow, suggesting that postprandial heat production is driven by altered mitochondrial function and changes in calcium cycling.
Bradycardic effects of microinjections of urocortin 3 into the nucleus ambiguus of the rat
Authors: Chitravanshi Vineet C. , Kawabe Kazumi , Sapru Hreday N.
Published: September 2012

The presence of urocortin 3 (UCN3) and CRF2 receptors (CRF2R) has been demonstrated in brain tissue. Nucleus ambiguus (nAmb) is the predominant brain area providing parasympathetic innervation to the heart. On the basis of these reports, it was hypothesized that activation of CRF2Rs in the nAmb may elicit cardiac effects. Experiments were carried out in urethane-anesthetized, artificially ventilated, and adult male Wistar rats. Microinjections of l-glutamate (l-GLU, 5 mM) were used to identify the nAmb. Different concentrations of UCN3 (0.031, 0.062, 0.125, 0.25, and 0.5 mM) microinjected into the nAmb elicited decreases in heart rate (HR) (5.3 ± 1, 22 ± 3.3, 38 ± 4.9, 45.7 ± 2.7, and 27.3 ± 2.3 bpm, respectively). The volume of all microinjections was 30 nl. Blood pressure changes concomitant with decreases in HR were not observed. Bradycardia elicited by microinjections of UCN3 (0.25 mM; maximally effective concentration) into the nAmb was significantly ( P < 0.05) attenuated by microinjections of selective CRF2R antagonists (K41498, 0.5 mM, and astressin 2B, 0.25 mM) at the same site. Bilateral vagotomy abolished the bradycardic responses to UCN3. These results indicated that activation of CRF2Rs in the nAmb by UCN3 elicited bradycardia, which was vagally mediated. UCNs have been reported to exert cardioprotective effects in heart failure and ischemia/reperfusion injury. In this situation, centrally induced bradycardia by UCN3 would be beneficial. The results of the present investigation provide a platform for future studies on the role of CRF2Rs in the nAmb in pathological states such as heart failure.
Glucagon-like peptide-1 receptor stimulation increases GFR and suppresses proximal reabsorption in the rat
Authors: Thomson Scott C. , Kashkouli Ali , Singh Prabhleen
Published: September 2012

The incretin hormone glucagon-like peptide-1 (GLP-1) is released from the gut in response to fat or carbohydrate and contributes to negative feedback control of blood glucose by stimulating insulin secretion, inhibiting glucagon, and slowing gastric emptying. GLP-1 receptors (GLP-1R) are also expressed in the proximal tubule, and possibly elsewhere in the kidney. Presently, we examined the effect of a GLP-1R agonist on single-nephron glomerular filtration rate (GFR; SNGFR), proximal reabsorption ( Jprox), tubuloglomerular feedback (TGF) responses, and urine flow rate in hydropenic male Wistar and Wistar-Froemter rats. Micropuncture and whole-kidney data were obtained before and during infusion of the GLP-1 agonist exenatide (1 nmol/h iv). SNGFR and Jprox were measured by late proximal collection at both extremes of TGF activation, which was achieved by perfusing Henle's loop at 0 or 50 nl/min. Primary changes in Jprox were revealed by analysis of covariance for Jprox with SNGFR as a covariate. Effects on TGF activation were determined in a separate set of experiments by comparing early distal and late proximal collections. Exenatide increased SNGFR by 33–50%, suppressed proximal tubular reabsorption by 20–40%, doubled early distal flow rate, and increased urine flow rate sixfold without altering the efficiency of glomerulotubular balance, TGF responsiveness, or the tonic influence of TGF. This implies that exenatide is both a proximal diuretic and a renal vasodilator. Since the natural agonist for the GLP-1R is regulated by intake of fat and carbohydrate, but not by salt or fluid, the control of salt excretion by the GLP-1R system departs from the usual negative-feedback paradigm for regulating salt balance.
Null mutations at the p66 and bradykinin 2 receptor loci induce divergent phenotypes in the diabetic kidney
Authors: Vashistha Himanshu , Singhal Pravin C. , Malhotra Ashwani , Husain Mohammad , Mathieson Peter , Saleem Moin A. , Kuriakose Cyril , Seshan Surya , Wilk Anna , DelValle Luis , Peruzzi Francesca , Giorgio Marco , Pelicci Pier Giuseppe , Smithies Oliver , Kim Hyung-Suk , Kakoki Masao , Reiss Krzysztof , Meggs Leonard G.
Published: September 2012

Candidate genes have been identified that confer increased risk for diabetic glomerulosclerosis (DG). Mice heterozygous for the Akita (Ins2+/C96Y) diabetogenic mutation with a second mutation introduced at the bradykinin 2 receptor (B2R−/−) locus express a disease phenotype that approximates human DG. Src homology 2 domain transforming protein 1 (p66) controls mitochondrial metabolism and cellular responses to oxidative stress, aging, and apoptosis. We generated p66-null Akita mice to test whether inactivating mutations at the p66 locus will rescue kidneys of Akita mice from disease-causing mutations at the Ins2 and B2R loci. Here we show null mutations at the p66 and B2R loci interact with the Akita (Ins2+/C96Y) mutation, independently and in combination, inducing divergent phenotypes in the kidney. The B2R−/−mutation induces detrimental phenotypes, as judged by increased systemic and renal levels of oxidative stress, histology, and urine albumin excretion, whereas the p66-null mutation confers a powerful protection phenotype. To elucidate the mechanism(s) of the protection phenotype, we turned to our in vitro system. Experiments with cultured podocytes revealed previously unrecognized cross talk between p66 and the redox-sensitive transcription factor p53 that controls hyperglycemia-induced ROS metabolism, transcription of p53 target genes (angiotensinogen, angiotensin II type-1 receptor, and bax), angiotensin II generation, and apoptosis. RNA-interference targeting p66 inhibits all of the above. Finally, protein levels of p53 target genes were upregulated in kidneys of Akita mice but unchanged in p66-null Akita mice. Taken together, p66 is a potential molecular target for therapeutic intervention in DG.
Effects of perilipin 2 antisense oligonucleotide treatment on hepatic lipid metabolism and gene expression
Authors: Imai Yumi , Boyle Siobhan , Varela Gladys M. , Caron Emilie , Yin Xiaoyan , Dhir Raina , Dhir Ravindra , Graham Mark J. , Ahima Rexford S.
Published: September 2012

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide. We previously showed that Perilipin 2 (Plin2), a member of lipid droplet protein family, is markedly increased in fatty liver, and its reduction in the liver of diet-induced obese mice by antisense oligonucleotide (ASO) decreased steatosis and enhanced insulin sensitivity. Plin2-ASO treatment markedly suppressed lipogenic gene expression. To gain a better understanding of the biological role of Plin2 in liver, we performed microarray analysis to determine genes differentially regulated by Plin2-ASO compared with a control (scrambled) oligonucleotide (Cont). Male C57BL/6J mice on a high-fat diet were treated with Plin2- or Cont-ASO for 4 wk. Plin2-ASO decreased hepatic triglycerides, and this was associated with changes in expression of 1,363 genes. We analyzed the data for functional clustering and validated the expression of representative genes using real-time PCR. On the high-fat diet, Plin2-ASO decreased the expression of enzymes involved in fatty acid metabolism ( acsl1, lipe) and steroid metabolism ( hmgcr, hsd3b5, hsd17b2), suggesting that Plin2 affects hepatic lipid metabolism at the transcriptional level. Plin2-ASO also increased the expression of genes involved in regulation of hepatocyte proliferation ( afp, H19), mitosis ( ccna2, incenp, sgol1), and extracellular matrix ( col1a1, col3a1, mmp8). Plin2-ASO had similar effects on gene expression in chow-fed mice. Together, these results indicate that Plin2 has diverse metabolic and structural roles in the liver, and its downregulation promotes hepatic fibrosis and proliferation.
Endometrial response of beef heifers on day 7 following insemination to supraphysiological concentrations of progesterone associated with superovulation
Authors: Forde N. , Carter F. , di Francesco S. , Mehta J. P. , Garcia-Herreros M. , Gad A. , Tesfaye D. , Hoelker M. , Schellander K. , Lonergan P.
Published: September 2012

Ovarian stimulation is a routine procedure in assisted reproduction to stimulate the growth of multiple follicles in naturally single-ovulating species including cattle and humans. The aim of this study was to analyze the changes induced in the endometrial transcriptome associated with superovulation in cattle and place these observations in the context of our previous data on changes in the endometrial transcriptome associated with elevated progesterone (P4) concentrations within the physiological range and those changes induced in the embryo due to superovulation. Mean serum P4 concentrations were significantly higher from day 4 to day 7 in superovulated compared with unstimulated control heifers ( P < 0.05). Between-group analysis revealed a clear separation in the overall transcriptional profile of endometria from unstimulated control heifers ( n = 5) compared with superovulated heifers ( n = 5). This was reflected in the number of differentially expressed genes (DEGs) identified between the two groups with 795 up- and 440 downregulated in superovulated endometria. Ten times more genes were altered by superovulation ( n = 1,234) compared with the number altered due to elevated P4 within physiological ranges by insertion of a P4-releasing intravaginal device ( n = 124) with only 22 DEGs common to both models of P4 manipulation. Fewer genes were affected by superovulation in the embryo compared with the endometrium, (443 vs. 1,234 DEGs, respectively), and the manner in which genes were altered was different with 64.5% of genes up- and 35.5% of genes downregulated in the endometrium, compared with the 98.9% of DEGs upregulated in the embryo. In conclusion, superovulation induces significant changes in the transcriptome of the endometrium which are distinct from those in the embryo.
Polymorphic Amplified Typing Sequences and Pulsed-Field Gel Electrophoresis Yield Comparable Results in the Strain Typing of a Diverse Set of BovineEscherichia coliO157:H7 Isolates
Authors: Kudva Indira T. , Davis Margaret A. , Griffin Robert W. , Garren Jeonifer , Murray Megan , John Manohar , Hovde Carolyn J. , Calderwood Stephen B.
Published: September 2012

Polymorphic amplified typing sequences (PATS), a PCR-basedEscherichia coliO157:H7 (O157) strain typing system, targets insertions-deletions and single nucleotide polymorphisms atXbaI andAvrII restriction enzyme sites, respectively, and the virulence genes (stx1,stx2,eae,hlyA) in the O157 genome. In this study, the ability of PATS to discriminate O157 isolates associated with cattle was evaluated. An in-depth comparison of 25 bovine O157 isolates, from different geographic locations across Northwest United States, showed that about 85% of these isolates shared the same dendogram clade by PATS and pulsed-field gel electrophoresis (PFGE), irrespective of the restriction enzyme sites targeted. The Pearson’s correlation coefficient,r, calculated at about 0.4, 0.3, and 0.4 forXbaI-based,AvrII-based and combined-enzymes PATS and PFGE similarities, respectively, indicating that these profiles shared a good but not high correlation, an expected inference given that the two techniques discriminate differently. Isolates that grouped differently were better matched to their locations using PATS. Overall, PATS discriminated the bovine O157 isolates without interpretive biases or sophisticated analytical software, and effectively complemented while not duplicating PFGE. With its quick turnaround time, PATS has excellent potential as a convenient tool for early epidemiological or food safety investigations, enabling rapid notification/implementation of quarantine measures.
Vibration of an Offshore Structure Having the Form of a Hollow Column Partially Filled with Multiple Fluids and Immersed in Water
Authors: Lin Hsien-Yuan , Lee Jeng-Nan , Sung Wen-Hao
Published: September 2012

This paper employs the numerical assembly method (NAM) to determine the exact frequency‐response amplitudes of an offshore structure such as piles or towers having the form of a hollow column filled with multiple fluids, immersed in water, carrying an eccentric tip mass supported by a translational spring and/or a rotational spring, and subjected to a harmonic force. The hollow column is modeled as a Bernoulli‐Euler cantilever beam fixed at the bottom. For the case of zero harmonic force, the simultaneous equations of the vibration system reduce to an eigenvalue problem so that the natural frequencies and mode shapes of the beam can also be obtained. The effect of height of filled fluids on the characteristics of free vibration is also presented.
On the Frame Properties of Degenerate System of Sines
Authors: Bilalov Bilal , Guliyeva Fatima
Published: September 2012

Systems of sines with degenerate coefficients are considered in this paper. Frame properties of these systems in Lebesgue spaces are studied.
Synthesis and Characterization of Metal Hydride/Carbon Aerogel Composites for Hydrogen Storage
Authors: Lin Kuen-Song , Mai Yao-Jen , Chiu Su-Wei , Yang Jing-How , Chan Sammy L. I.
Published: September 2012

Two materials currently of interest for onboard lightweight hydrogen storage applications are sodium aluminum hydride (NaAlH4), a complex metal hydride, and carbon aerogels (CAs), a light porous material connected by several spherical nanoparticles. The objectives of the present work have been to investigate the synthesis, characterization, and hydrogenation behavior of Pd‐, Ti‐ or Fe‐doped CAs, NaAlH4, and MgH2 nanocomposites. The diameters of Pd nanoparticles onto CA’s surface and BET surface area of CAs were 3–10 nm and 700–900 m2g−1, respectively. The H2 storage capacity of metal hydrides has been studied using high‐pressure TGA microbalance and they were 4.0, 2.7, 2.1, and 1.2 wt% for MgH2‐FeTi‐CAs, MgH2‐FeTi, CAs‐Pd, and 8 mol% Ti‐doped NaAlH4, respectively, at room temperature. Carbon aerogels with higher surface area and mesoporous structures facilitated hydrogen diffusion and adsorption, which accounted for its extraordinary hydrogen storage phenomenon. The hydrogen adsorption abilities of CAs notably increased after inclusion of metal hydrides by the “hydrogen spillover” mechanisms.
Durable Effect of Radioactive Iodine in a Patient with Metastatic Follicular Thyroid Carcinoma
Authors: Carhill Aubrey A. , Vassilopoulou-Sellin Rena
Published: September 2012

Objective. Thyroid cancer is the most common endocrine malignancy and fastest increasing of all cancers in both men and women in the United States. Traditionally, differentiated thyroid cancer (DTC) carries a good prognosis when diagnosed early, but increasingly patients are presenting with late-stage disease and bone metastasis which carries a poor prognosis. Treatment of DTC involves surgical resection followed by radioactive iodine (RAI), which conventionally is thought to reach maximal effectiveness between 6 and 12 months following treatment. We report a case and review the literature surrounding long-term effect of radioactive iodine treatment in metastatic thyroid carcinoma.Methods. Patient clinical encounter and the literature review.Results. We describe a 49-year-old woman with symptomatic metastatic follicular thyroid cancer (FTC) to the spine and radiographic evidence of spinal cord compression who was effectively treated with RAI. Her initial serum thyroglobulin (Tg) levels following total thyroidectomy were 1,343 ng/mL which dramatically dropped to less than 100 ng/mL following RAI. Forty-three months following treatment with RAI, she has experienced complete resolution of her symptoms and continues to maintain persistently low-thyroglobulin levels of less than 100 ng/mL.Conclusions. RAI is believed to reach peak efficacy within 6–12 months; however, little has been reported regarding the long-term duration of benefit. This case demonstrates that the benefits of RAI therapy may be enduring, even in patients with widely metastatic thyroid cancer. It suggests in clinically stable patients with declining thyroglobulin after treatment, that there may not be an immediate need for additional therapy as RAI treatment may provide lasting effects.