bluuebunny/crossref_metadata_2025 huggingface dataset:
In Vivo Reversion to the Wild-Type β-Lactam Resistance Phenotype Mediated by a Plasmid CarryingampRandqnrA1inEnterobacter cloacae
Authors: González-López J. J. , Sabaté M. , Lavilla S. , Larrosa M. N. , Bartolomé R. M. , Prats G.
Published: August 2006

Resistance to β-lactams and quinolones in two isogenicEnterobacter cloacaeisolates was studied. One was susceptible to cefoxitin and amoxicillin-clavulanate. The other one showed its natural β-lactam resistance pattern. Both isolates had a nonfunctional AmpR regulator. However, within the second one, the presence of a plasmid carryingampRandqnrA1allowed reversion to the wild-type β-lactam resistance phenotype and decreased susceptibility to fluoroquinolones.
Mobilizable IncQ-Related Plasmid Carrying a New Quinolone Resistance Gene,
qnrS2
, Isolated from the Bacterial Community of a Wastewater Treatment Plant
Authors: Bönemann Gabriele , Stiens Michael , Pühler Alfred , Schlüter Andreas
Published: August 2006

Plasmid-encoded quinolone resistance was previously reported for different bacteria isolated from patients not only in the United States and Asia but also in Europe. Here we describe the isolation, by applying a new selection strategy, of the quinolone resistance plasmid pGNB2 from an activated sludge bacterial community of a wastewater treatment plant in Germany. The hypersensitive
Escherichia coli
strain KAM3 carrying a mutation in the multidrug efflux system genes
acrAB
was transformed with total plasmid DNA preparations isolated from activated sludge bacteria and subsequently selected on medium containing the fluoroquinolone norfloxacin. This approach resulted in the isolation of plasmid pGNB2 conferring decreased susceptibility to nalidixic acid and to different fluoroquinolones. Analysis of the pGNB2 nucleotide sequence revealed that it is 8,469 bp in size and has a G+C content of 58.2%. The plasmid backbone is composed of a replication initiation module (
repA-repC
) belonging to the IncQ-family and a two-component mobilization module that confers horizontal mobility to the plasmid. In addition, plasmid pGNB2 carries an accessory module consisting of a transposon Tn
1721
remnant and the quinolone resistance gene,
qnrS2
, that is 92% identical to the
qnrS
gene located on plasmid pAH0376 from
Shigella flexneri
2b. QnrS2 belongs to the pentapeptide repeat protein family and is predicted to protect DNA-gyrase activity against quinolones. This is not only the first report on a completely sequenced plasmid mediating quinolone resistance isolated from an environmental sample but also on the first
qnrS
-like gene detected in Europe.
A Novel Extended-Spectrum TEM-Type β-Lactamase, TEM-138, from
Salmonella enterica
Serovar Infantis
Authors: Chouchani Chedly , Berlemont Renaud , Masmoudi Afef , Galleni Moreno , Frere Jean-Marie , Belhadj Omrane , Ben-Mahrez Kamel
Published: August 2006

A novel natural TEM β-lactamase with extended-spectrum activity, TEM-138, was identified in a ceftazidime-resistant clinical isolate of
Salmonella enterica
serovar Infantis. Compared to TEM-1, TEM-138 contains the following mutations: E104K, N175I, and G238S. The
bla
TEM-138
gene was located on a 50-kb transferable plasmid. Expression studies with
Escherichia coli
revealed efficient ceftazidimase and cefotaximase activities for TEM-138.
Tetracyclines Specifically Target the Apicoplast of the Malaria Parasite
Plasmodium falciparum
Authors: Dahl Erica L. , Shock Jennifer L. , Shenai Bhaskar R. , Gut Jiri , DeRisi Joseph L. , Rosenthal Philip J.
Published: August 2006

Tetracyclines are effective but slow-acting antimalarial drugs whose mechanism of action remains uncertain. To characterize the antimalarial mechanism of tetracyclines, we evaluated their stage-specific activities, impacts on parasite transcription, and effects on two predicted organelle targets, the apicoplast and the mitochondrion, in cultured
Plasmodium falciparum
. Antimalarial effects were much greater after two 48-h life cycles than after one cycle, even if the drugs were removed at the end of the first cycle. Doxycycline-treated parasites appeared morphologically normal until late in the second cycle of treatment but failed to develop into merozoites. Doxycycline specifically impaired the expression of apicoplast genes. Apicoplast morphology initially appeared normal in the presence of doxycycline. However, apicoplasts were abnormal in the progeny of doxycycline-treated parasites, as evidenced by a block in apicoplast genome replication, a lack of processing of an apicoplast-targeted protein, and failure to elongate and segregate during schizogeny. Replication of the nuclear and mitochondrial genomes and mitochondrial morphology appeared normal. Our results demonstrate that tetracyclines specifically block expression of the apicoplast genome, resulting in the distribution of nonfunctional apicoplasts into daughter merozoites. The loss of apicoplast function in the progeny of treated parasites leads to a slow but potent antimalarial effect.
Combination of Suboptimal Doses of Inhibitors Targeting Different Domains of LtrMDR1 Efficiently Overcomes Resistance of
Leishmania
spp. to Miltefosine by Inhibiting Drug Efflux
Authors: Pérez-Victoria José M. , Cortés-Selva Fernando , Parodi-Talice Adriana , Bavchvarov Boris I. , Pérez-Victoria F. Javier , Muñoz-Martínez Francisco , Maitrejean Mathias , Costi M. Paola , Barron Denis , Di Pietro Attilio , Castanys Santiago , Gamarro Francisco
Published: August 2006

Miltefosine (hexadecylphosphocholine) is the first orally active drug approved for the treatment of leishmaniasis. We have previously shown the involvement of LtrMDR1, a P-glycoprotein-like transporter belonging to the ATP-binding cassette superfamily, in miltefosine resistance in
Leishmania
. Here we show that overexpression of LtrMDR1 increases miltefosine efflux, leading to a decrease in drug accumulation in the parasites. Although LtrMDR1 modulation might be an efficient way to overcome this resistance, a main drawback associated with the use of P-glycoprotein inhibitors is related to their intrinsic toxicity. In order to diminish possible side effects, we have combined suboptimal doses of modulators targeting both the cytosolic and transmembrane domains of LtrMDR1. Preliminary structure-activity relationships have allowed us to design a new and potent flavonoid derivative with high affinity for the cytosolic nucleotide-binding domains. As modulators directed to the transmembrane domains, we have selected one of the most potent dihydro-β-agarofuran sesquiterpenes described, and we have also studied the effects of two of the most promising, latest-developed modulators of human P-glycoprotein, zosuquidar (LY335979) and elacridar (GF120918). The results show that this combinatorial strategy efficiently overcomes P-glycoprotein-mediated parasite miltefosine resistance by increasing intracellular miltefosine accumulation without any side effect in the parental, sensitive,
Leishmania
line and in different mammalian cell lines.
Intracellular Penetration and Activity of DX-619 in Human Polymorphonuclear Leukocytes
Authors: García Isabel , Ballesta Sofía , Murillo Concepción , Perea Evelio J. , Pascual Álvaro
Published: August 2006

The intracellular penetration and activity of DX-619 in human polymorphonuclear leukocytes have been evaluated. DX-619 reached intracellular concentrations 10 times higher than the extracellular concentrations reached. Uptake was rapid, reversible, nonsaturable, and affected by environmental temperature, some metabolic inhibitors, and a soluble membrane activator. DX-619 showed intracellular activity againstStaphylococcus aureus.
Effect of Treatment Duration on Pharmacokinetic/Pharmacodynamic Indices Correlating with Therapeutic Efficacy of Ceftazidime in Experimental
Klebsiella pneumoniae
Lung Infection
Authors: Bakker-Woudenberg Irma A. J. M. , ten Kate Marian T. , Goessens Wil H. F. , Mouton Johan W.
Published: August 2006

The pharmacokinetic/pharmacodynamic (PK/PD) indices that define the therapeutic effect of the beta-lactam ceftazidime in a rat model of
Klebsiella pneumoniae
lung infection were investigated in relation to treatment duration and treatment endpoint. Treatment was started 24 h after infection with dosing regimens of 3.1 up to 1,600 mg/kg of body weight/day and dosing every 6, 12, or 24 h. When animals were treated for a relatively short period of 48 h, the duration of time that unbound plasma ceftazidime levels exceeded the MIC of the antibiotic for the infecting strain was the index that best correlated with therapeutic efficacy in terms of significant bacterial killing in the infected lung (microbiological effect). The maximum effect was reached when plasma ceftazidime levels were above the MIC for 60 to 70% of the dosing interval. However, when the treatment duration was extended to a relatively long period of 18 days instead of 48 h and animal survival rate instead of microbiological efficacy was taken as the endpoint, the
f
AUC/MIC ratio (where AUC is the area under the concentration-time curve) was the PK/PD index that best correlated with therapeutic efficacy. The PK/PD indices that effect 50% survival of rats for the
f
AUC/MIC ratios were 18.0 (95% confidence interval [95% CI], 16.3 to 19.9), 20.2 (95% CI, 13.8 to 29.4), and 27.9 (95% CI, 21.3 to 36.5) for the schedules of administration of every 6, 12, and 24 h, respectively. The
f
AUC/MIC needed for 100% survival was >100. We conclude that the PK/PD index that best correlates with outcome is dependent on the duration of treatment and/or the parameter of outcome. The effect of long-term treatment should be studied more extensively in other models of infection.
Efficacy of Cethromycin, a New Ketolide, against
Streptococcus pneumoniae
Susceptible or Resistant to Erythromycin in a Murine Pneumonia Model
Authors: Azoulay-Dupuis E. , Mohler J. , Bédos J. P. , Barau C. , Fantin B.
Published: August 2006

Cethromycin is a ketolide with in vitro activity against macrolide-sensitive and -resistant strains of
Streptococcus pneumoniae
. We compared its in vivo efficacy to erythromycin in a mouse model of acute pneumonia induced by two virulent clinical strains: a serotype 3 susceptible strain (P-4241) (MICs: erythromycin, 0.03 μg/ml; cethromycin, 0.015 μg/ml) and a serotype 1 strain resistant to erythromycin (P-6254; phenotypically MLSB constitutive) (MICs: erythromycin, 1,024 μg/ml; cethromycin, 0.03 μg/ml). Immunocompetent mice were infected with 10
5
CFU of each strain. Six treatments given either subcutaneously (s.c.) or per os (p.o.) at 12-h intervals were initiated at 6 or 12 h after infection. Against P-4241, cethromycin given s.c. at 25 or 12.5 mg/kg protected 100% of the animals, with lungs and blood completely cleared of bacteria. Given p.o., cethromycin maintained its efficacy with 100 and 86% survival at 25 and 12.5 mg/kg, respectively. Erythromycin, given s.c. at 50 or 37.5 mg/kg, provided 50 and 38% survival rates, respectively. Against P-6254, cethromycin was effective at 25 mg/kg (100% survival) regardless of the administration route, whereas only 25 and 8% of animals survived after a 75-mg/kg erythromycin treatment given s.c. and p.o., respectively. The serum protein binding levels of cethromycin were 94.8 and 88.5% after doses of 12.5 and 25 mg/kg, respectively. The higher in vivo activity of cethromycin compared to erythromycin could be explained by favorable pharmacokinetic/pharmacodynamic indexes against P-6254 but not against P-4241.
Activity of Picolinic Acid in Combination with the Antiprotozoal Drug Quinacrine against
Mycobacterium avium
Complex
Authors: Shimizu Toshiaki , Tomioka Haruaki
Published: August 2006

We studied the in vitro and in vivo antimicrobial activities of picolinic acid (PA) in combination with the antiprotozoal drug quinacrine against intramacrophage
Mycobacterium avium
complex (MAC). Quinacrine significantly potentiated the anti-MAC activity of PA, suggesting the usefulness of this combination in the clinical control of MAC infection.
Detection of Extended-Spectrum β-Lactamases in Clinical Isolates of
Pseudomonas aeruginosa
Authors: Jiang Xiaofei , Zhang Zhe , Li Min , Zhou Danqiu , Ruan Feiyi , Lu Yuan
Published: August 2006

With the occurrence of extended-spectrum β-lactamases (ESBLs) in
Pseudomonas aeruginosa
being increasingly reported worldwide, there is a need for a reliable test to detect ESBLs in clinical isolates of
P. aeruginosa
. In our study, a total of 75 clinical isolates of
P. aeruginosa
were studied. Nitrocefin tests were performed to detect the β-lactamase enzyme; isoelectric focusing electrophoresis, PCR, and PCR product sequencing were designed to further characterize the contained ESBLs. Various ESBL-screening methods were designed to compare the reliabilities of detecting ESBLs in clinical isolates of
P. aeruginosa
whose β-lactamases were well characterized. Thirty-four of 36 multidrug-resistant
P. aeruginosa
clinical isolates were positive for ESBLs.
bla
VEB-3
was the most prevalent ESBL gene in
P. aeruginosa
in our study. Among the total of 34 isolates that were considered ESBL producers, 20 strains were positive using conventional combined disk tests and 10 strains were positive using a conventional double-disk synergy test (DDST) with amoxicillin-clavulanate, expanded-spectrum cephalosporins, aztreonam, and cefepime. Modifications of the combined disk test and DDST, which consisted of shorter distances between disks (20 mm instead of 30 mm) and the use of three different plates that contained cloxacillin (200 μg/ml) alone, Phe-Arg β-naphthylamide dihydrochloride (MC-207,110; 20 μg/ml) alone, and both cloxacillin (200 μg/ml) and MC-207,110 (20 μg/ml) increased the sensitivity of the tests to 78.8%, 91.18%, 85.29%, and 97.06%.
Comparative Efficacies of Amoxicillin, Clindamycin, and Moxifloxacin in Prevention of Bacteremia following Dental Extractions
Authors: Diz Dios P. , Tomás Carmona I. , Limeres Posse J. , Medina Henríquez J. , Fernández Feijoo J. , Álvarez Fernández M.
Published: August 2006

We evaluated the efficacies of oral prophylactic treatment with amoxicillin (AMX), clindamycin (CLI), and moxifloxacin (MXF) in the prevention of bacteremia following dental extractions (BDE). Two hundred twenty-one adults who required dental extractions under general anesthesia were randomly assigned to a control group, an AMX group, a CLI group, and an MXF group (the individuals in the drug treatment groups received 2 g, 600 mg, and 400 mg, respectively, 1 to 2 h before anesthesia induction). Venous blood samples were collected from each patient at the baseline and 30 s, 15 min, and 1 h after the dental extractions. The samples were inoculated into BACTEC Plus aerobic and anaerobic blood culture bottles and were processed in a BACTEC 9240 instrument. Subculture and the further identification of the isolated bacteria were performed by conventional microbiological techniques. The prevalences of BDE in the control group, AMX group, CLI group, and MXF group were 96, 46, 85, and 57%, respectively, at 30 s; 64, 11, 70, and 24%, respectively, at 15 min; and 20, 4, 22, and 7%, respectively, at 1 h.
Streptococcus
spp. were the most frequently identified bacteria in all groups (44 to 68%), with the lowest percentage being detected in the AMX group (44%). AMX and MXF prophylaxis showed high efficacies in reducing the prevalence and duration of BDE, but CLI prophylaxis was noneffective. As a consequence, MXF prophylaxis is a promising antibiotic alternative for the prevention of BDE when beta-lactams are not indicated.
Inhibition of Human Immunodeficiency Virus Type 1 Entry by a Binding Domain of
Porphyromonas gingivalis
Gingipain
Authors: Xie Hua , Belogortseva Natalya I. , Wu Jie , Lai Wei-Hong , Chen Chin-ho
Published: August 2006

Human immunodeficiency virus (HIV) transmission through saliva is extremely low. Several oral components, including secretory immunoglobulin A and secretory leukocyte protease inhibitor, are known as potential inhibitory agents of HIV oral transmission. Here we examined anti-HIV activity of oral bacterial components. We showed that recombinant protein HGP44 derived from
Porphyromonas gingivalis
, one of the primary infectious agents of periodontitis, was capable of inhibiting HIV type 1 (HIV-1) replication. HGP44 bound specifically to HIV-1 gp120 and blocked HIV-1 envelope-mediated membrane fusion. These findings suggest that HGP44 of
P. gingivalis
can inhibit HIV-1 infection by blocking HIV-1 entry.
High-Affinity Aptamers to Subtype 3a Hepatitis C Virus Polymerase Display Genotypic Specificity
Authors: Jones Louisa A. , Clancy Leighton E. , Rawlinson William D. , White Peter A.
Published: August 2006

Research into antiviral agents directed at hepatitis C virus (HCV) proteins is commonly based and tested on a single genotype, namely, genotype 1. This is despite the high level of variability of the RNA virus and the frequency of infection with genotypes other than genotype 1. The systematic evolution of ligands by exponential enrichment (SELEX) is a novel in vitro approach used in this study that allows rapid screening of vast nucleic acid libraries to isolate sequences (termed aptamers) that bind to target proteins with high affinity. The SELEX approach was used in the present study to isolate DNA aptamers to the RNA-dependent RNA polymerase (RdRp) (nonstructural protein 5B [NS5B]) of HCV subtype 3a, with the aim of inhibiting polymerase activity. Ten rounds of selection were performed using a Biacore 2000 as the partitioning system. Two aptamers, r10/43 and r10/47, were chosen for further studies on the basis of their abilities to bind the HCV RdRp and inhibit polymerase activity. The affinities (equilibrium dissociation constants) of these aptamers for the HCV subtype 3a polymerase were estimated to be 1.3 ± 0.3 nM (r10/43) and 23.5 ± 6.7 nM (r10/47). The inhibition constants of r10/43 and r10/47 were estimated to be 1.4 ± 2.4 nM and 6.0 ± 2.3 nM, respectively. Inhibition of HCV 3a polymerase was specific for r10/47, while r10/43 also demonstrated some inhibitory effect on norovirus and φ6 polymerase activity. Neither r10/43 nor r10/47 was able to inhibit the RdRp activity of HCV genotype 1a and 1b polymerases. This study is the first description of an inhibitor specific to the HCV subtype 3a polymerase.
Critical Design Features of Phenyl Carboxylate-Containing Polymer Microbicides
Authors: Rando Robert F. , Obara Sakae , Osterling Mark C. , Mankowski Marie , Miller Shendra R. , Ferguson Mary L. , Krebs Fred C. , Wigdahl Brian , Labib Mohamed , Kokubo Hiroyasu
Published: August 2006

Recent studies of cellulose-based polymers substituted with carboxylic acids like cellulose acetate phthalate (CAP) have demonstrated the utility of using carboxylic acid groups instead of the more common sulfate or sulfonate moieties. However, the pK
a
of the free carboxylic acid group is very important and needs careful selection. In a polymer like CAP the pK
a
is approximately 5.28. This means that under the low pH conditions found in the vaginal lumen, CAP would be only minimally soluble and the carboxylic acid would not be fully dissociated. These issues can be overcome by substitution of the cellulose backbone with a moiety whose free carboxylic acid group(s) has a lower pK
a
. Hydroxypropyl methylcellulose trimellitate (HPMCT) is structurally similar to CAP; however, its free carboxylic acids have pK
a
s of 3.84 and 5.2. HPMCT, therefore, remains soluble and molecularly dispersed at a much lower pH than CAP. In this study, we measured the difference in solubility and dissociation between CAP and HPMCT and the effect these parameters might have on antiviral efficacy. Further experiments revealed that the degree of acid substitution of the cellulose backbone can significantly impact the overall efficacy of the polymer, thereby demonstrating the need to optimize any prospective polymer microbicide with respect to pH considerations and the degree of acid substitution. In addition, we have found HPMCT to be a potent inhibitor of CXCR4, CCR5, and dual tropic strains of human immunodeficiency virus in peripheral blood mononuclear cells. Therefore, the data presented herein strongly support further evaluation of an optimized HPMCT variant as a candidate microbicide.
From compliance to concordance in diabetes
Authors: Chatterjee J S
Published: August 2006

Compliance is a key concept in health care and affects all areas of health care including diabetes. Non-compliance has previously been a label attached to many patients without much thought having been given to the causes of poor compliance. Over the last few decades there has been a large volume of research focusing on compliance that has exposed the multitude of factors affecting compliance. Even the definition is not clear cut and so comparability between studies is not without difficulties. A better understanding of the factors affecting compliance, including the doctor/patient relationship, has allowed the evolution of “concordance”. Concordance views the patient as being the equal of the healthcare provider and as having a right to make informed decisions. In a condition such as diabetes, which has many potential long term complications, it is vital that concordance is embraced in the healthcare system in order to improve care.
Privacy and occupational health services
Authors: Heikkinen A , Launis V , Wainwright P , Leino-Kilpi H
Published: August 2006

Privacy is a key ethical principle in occupational health services. Its importance is emphasised in several laws, in ethical codes of conduct as well as in the literature, yet there is only very limited empirical research on privacy in the occupational health context. Conceptual questions on privacy in the occupational health context are discussed. The baseline assumption is that, in this context, privacy cannot be approached and examined only from the employee’s (an individual) vantage point but the employer’s (a group) point of view must also be taken into account, and that the concept has several dimensions (physical, social, informational and psychological). Even though privacy is a basic human need, there is no universally accepted definition of the concept and no consensus on whether an organisation can have privacy in the same way as people do. Many of the challenges surrounding privacy in the context of occupational health seem to be associated with the dual loyalties of occupational health professionals towards the employee and employer and with their simultaneous duties of disseminating and protecting information (informational privacy). Privacy is thus not an absolute value, but more research is needed to understand its multidimensional nature in the context of occupational health.
Public health and human values: Table 1
Authors: Häyry M
Published: August 2006

The ends and means of public health activities are suggested to be at odds with the values held by human individuals and communities. Although promoting longer lives in better health for all seems like an endeavour that is obviously acceptable, it can be challenged by equally self-evident appeals to autonomy, happiness, integrity and liberty, among other values. The result is that people’s actual concerns are not always adequately dealt with by public health measures and assurances.
Why doctors use or do not use ethics consultation
Authors: Orlowski J P , Hein S , Christensen J A , Meinke R , Sincich T
Published: August 2006

Background:Ethics consultation is used regularly by some doctors, whereas others are reluctant to use these services.

Aim:To determine factors that may influence doctors to request or not request ethics consultation.

Methods:A survey questionnaire was distributed to doctors on staff at the University Community Hospital in Tampa, Florida, USA. The responses to the questions on the survey were arranged in a Likert Scale, from strongly disagree, somewhat disagree, neither agree nor disagree, somewhat agree to strongly agree. Data were analysed with the Wilcoxon test for group comparisons, the χ2test to compare proportions and a logistic regression analysis.

Results:Of the 186 surveys distributed, 121 were returned, giving a 65% response rate. Demographic data were similar between the groups saying yes (I do/would use ethics consultation when indicated) and no (I do not/would not use ethics consultation when indicated). No statistically significant differences were observed between the user and non-user groups in terms of opinions about ethics consultants having extensive training in ethics or participating in ethics educational opportunities. On the issue “Ethics committee members or consultants cannot grasp the full picture from the outside”, the non-users were neutral, whereas the users somewhat disagreed (p = 0.012). Even more significant was the difference between surgeons and non-surgeons, where, by logistic regression analysis, surgeons who believed that ethics consultants could not grasp the full picture from the outside were highly likely to not use (p = 0.0004). Non-users of ethics consultations thought that it was their responsibility to resolve issues with the patient or family (72.2% agree, p<0.05). Users of ethics consultation believed in shared decision making or the importance of alternate points of view (90.8% agree, p<0.05).

Implications:Ethics consultations are used by doctors who believe in shared decision making. Doctors who did not use ethics consultation tended to think that it was their responsibility to resolve issues with patients and families and that they were already proficient in ethics.
Oxygen regulation of macrophage migration inhibitory factor in human placenta
Authors: Ietta Francesca , Wu Yuanhong , Romagnoli Roberta , Soleymanlou Nima , Orsini Barbara , Zamudio Stacy , Paulesu Luana , Caniggia Isabella
Published: August 2006

Macrophage migration inhibitory factor (MIF) is an important proinflammatory cytokine involved in regulation of macrophage function. In addition, MIF may also play a role in murine and human reproduction. Although both first trimester trophoblast and decidua express MIF, the regulation and functional significance of this cytokine during human placental development remains unclear. We assessed MIF expression throughout normal human placental development, as well as in in vitro (chorionic villous explants) and in vivo (high altitude placentae) models of human placental hypoxia. Dimethyloxalylglycine (DMOG), which stabilizes hypoxia inducible factor-1 under normoxic conditions, was also used to mimic the effects of hypoxia on MIF expression. Quantitative real-time PCR and Western blot analysis showed high MIF protein and mRNA expression at 7–10 wk and lower levels at 11–12 wk until term. Exposure of villous explants to 3% O2 resulted in increased MIF expression and secretion relative to standard conditions (20% O2). DMOG treatment under 20% O2 increased MIF expression. In situ hybridization and immunohistochemistry showed elevated MIF expression in low oxygen-induced extravillous trophoblast cells. Finally, a significant increase in MIF transcript was observed in placental tissues from high-altitude pregnancies. Hence, three experimental models of placental hypoxia (early gestation, DMOG treatment, and high altitude) converge in stimulating increased MIF, supporting the conclusion that placental-derived MIF is an oxygen-responsive cytokine highly expressed in physiological in vivo and in in vitro low oxygen conditions.
Mechanisms for gonadotropin-releasing hormone potentiation of growth hormone rebound following norepinephrine inhibition in goldfish pituitary cells
Authors: Wong Anderson O. L. , Chuk Maggie C. Y. , Chan Hiu Chi , Lee Eric K. Y.
Published: August 2006

In the goldfish, norepinephrine (NE) inhibits growth hormone (GH) secretion through activation of pituitary α2-adrenergic receptors. Interestingly, a GH rebound is observed after NE withdrawal, which can be markedly enhanced by prior exposure to gonadotropin-releasing hormone (GnRH). Here we examined the mechanisms responsible for GnRH potentiation of this “postinhibition” GH rebound. In goldfish pituitary cells, α2-adrenergic stimulation suppressed both basal and GnRH-induced GH mRNA expression, suggesting that a rise in GH synthesis induced by GnRH did not contribute to its potentiating effect. Using a column perifusion approach, GnRH given during NE treatment consistently enhanced the GH rebound following NE withdrawal. This potentiating effect was mimicked by activation of PKC and adenylate cyclase (AC) but not by induction of Ca2+ entry through voltage-sensitive Ca2+ channels (VSCC). Furthermore, GnRH-potentiated GH rebound could be alleviated by inactivation of PKC, removal of extracellular Ca2+, blockade of VSCC, and inhibition of Ca2+/calmodulin (CaM)-dependent protein kinase II (CaMKII). Inactivation of AC and PKA, however, was not effective in this regard. These results, as a whole, suggest that GnRH potentiation of GH rebound following NE inhibition is mediated by PKC coupled to Ca2+ entry through VSCC and subsequent activation of CaMKII. Apparently, the Ca2+-dependent cascades are involved in GH secretion during the rebound phase but are not essential for the initiation of GnRH potentiation. Since GnRH has been previously shown to have no effects on cAMP synthesis in goldfish pituitary cells, the involvement of cAMP-dependent mechanisms in GnRH potentiation is rather unlikely.
Amine Modulation of Ih in a Small Neural Network
Authors: Peck Jack H. , Gaier Eric , Stevens Erin , Repicky Sarah , Harris-Warrick Ronald M.
Published: August 2006

We studied the functional role and modulation of the hyperpolarization-activated inward current ( Ih) in the pyloric network of the lobster stomatogastric ganglion. In isolated neurons, Ih is a small current with a hyperpolarized voltage of half-activation ( VAct) and a slow time constant of activation (τAct). Bath application of dopamine (DA), octopamine (OCT), or serotonin (5HT) modified Ih in selected synaptically isolated pyloric neurons. DA significantly enhanced Ih in the anterior burster (AB) neuron by depolarizing its VAct, accelerating its τAct, and enhancing its maximal conductance ( gmax). DA more weakly enhanced Ih in the pyloric constrictor (PY) and ventricular dilator (VD) neurons. OCT weakly depolarized VAct and accelerated τAct in the VD and inferior cardiac (IC) neurons. 5HT depolarized VAct in the IC neuron. Under control conditions with intact modulatory inputs from other ganglia, the pyloric rhythm cycles strongly at about 1–2 Hz. Bath application of the Ih blocker cesium (Cs+) caused a mean increase in the period of 8%, although this effect was highly variable. When Cs+ was applied to an isolated ganglion where the pyloric rhythm had been activated only by DA, the cycle period was consistently increased by 13.5%, with no other strong changes in rhythm parameters. These results suggest that Ih regulates the pyloric rhythm by accelerating AB pacemaker frequency, but that this effect can vary with the modulatory conditions.
Changes in Stretch Reflex Excitability Are Related to “Giving Way” Symptoms in Patients With Anterior Cruciate Ligament Rupture
Authors: Melnyk M. , Faist M. , Gothner M. , Claes L. , Friemert B.
Published: August 2006

A rupture of the anterior cruciate ligament (ACL) usually leads to an altered stretch reflex excitability of the thigh muscles that stabilize the knee. The purpose of this study was to quantitatively assess reflex activity in the m. semitendinosus/semimembranosus after anterior tibial translation in 21 patients with isolated ACL ruptures. The patients were divided into a group with “giving way” symptoms (noncopers, n = 12) and a group without “giving way” symptoms (copers, n = 9). While the patients were standing upright with 30° knee flexion, a force of 300 N was applied to the knee to induce posterior–anterior tibial translation. Activity of m. semitendinosus/semimembranosus was measured using surface electromyography (EMG). A linear potentiometer was placed on the tibial tuberosity and measured maximum tibial translation during standing (i.e., functional condition). In addition, knee laxity was assessed with a KT1000 arthrometer under passive conditions. After ACL rupture, the short-latency response (SLR) latency remained unchanged ( P = 0.21), whereas for the medium-latency response (MLR) it was significantly longer ( P < 0.001). Significantly longer MLR latencies were noted for noncopers compared with copers ( P < 0.01), whereas SLR latencies were similar. Significant differences between healthy and injured legs were noted after tibial translations using KT1000 ( P < 0.001) and during stance ( P < 0.001). Mechanical knee instability was found to be unchanged between copers and noncopers (KT1000: P = 0.97; tibial translation: P = 0.31). These results indicate that ACL rupture is associated with altered stretch reflex excitability, which may lead to “giving way” symptoms, and that altered stretch reflex excitability may be more important for the development of “giving way” than the mechanical instability of the knee.
Transcriptome of the subcutaneous adipose tissue in response to oral supplementation of type 2 Leprdb obese diabetic mice with niacin-bound chromium
Authors: Rink Cameron , Roy Sashwati , Khanna Savita , Rink Trenton , Bagchi Debasis , Sen Chandan K.
Published: August 2006

The effects of oral niacin-bound chromium (NBC) supplementation on the subcutaneous fat tissue of type 2 Lepr db obese diabetic mice were examined using high-density comprehensive mouse genome (45,101 probe sets) expression arrays. The influence of such supplementation on the plasma cardiovascular risk factors of these mice was also investigated. Supplementation of NBC had no significant effect on age-dependent weight gain in the Lepr db obese diabetic mice. However, NBC lowered total cholesterol (TC), TC-to-HDL ratio, LDL cholesterol, and triglyceride levels while increasing HDL cholesterol in the blood plasma. No effect of NBC supplementation was observed on fasting blood glucose levels. Oral glucose tolerance test revealed a significantly improved clearance of blood glucose between 1 and 2 h of glucose challenge in NBC-supplemented mice. Unbiased genome-wide interrogation demonstrated that NBC resulted in the upregulation of muscle-specific gene expression in the fat tissue. Genes encoding proteins involved in glycolysis, muscle contraction, muscle metabolism, and muscle development were specifically upregulated in response to NBC supplementation. Genes in the adipose tissue that were downregulated in response to NBC supplementation included cell death-inducing DNA fragmentation factor (CIDEA) and uncoupling protein-1, which represent key components involved in the thermogenic role of brown adipose tissue and tocopherol transfer protein, the primary carrier of α-tocopherol to adipose tissue. The observation that CIDEA-null mice are resistant to obesity and diabetes suggests that the inhibitory role of NBC on CIDEA expression was favorable. Further studies testing the molecular basis of NBC function and long-term outcomes are warranted.
BAC transgenic mice express enhanced green fluorescent protein in central and peripheral cholinergic neurons
Authors: Tallini Yvonne N. , Shui Bo , Greene Kai Su , Deng Ke-Yu , Doran Robert , Fisher Patricia J. , Zipfel Warren , Kotlikoff Michael I.
Published: August 2006

The peripheral nervous system has complex and intricate ramifications throughout many target organ systems. To date this system has not been effectively labeled by genetic markers, due largely to inadequate transcriptional specification by minimum promoter constructs. Here we describe transgenic mice in which enhanced green fluorescent protein (eGFP) is expressed under the control of endogenous choline acetyltransferase (ChAT) transcriptional regulatory elements, by knock-in of eGFP within a bacterial artificial chromosome (BAC) spanning the ChAT locus and expression of this construct as a transgene. eGFP is expressed in ChATBAC-eGFP mice in central and peripheral cholinergic neurons, including cell bodies and processes of the somatic motor, somatic sensory, and parasympathetic nervous system in gastrointestinal, respiratory, urogenital, cardiovascular, and other peripheral organ systems. Individual epithelial cells and a subset of lymphocytes within the gastrointestinal and airway mucosa are also labeled, indicating genetic evidence of acetylcholine biosynthesis. Central and peripheral neurons were observed as early as 10.5 days postcoitus in the developing mouse embryo. ChATBAC-eGFP mice allow excellent visualization of all cholinergic elements of the peripheral nervous system, including the submucosal enteric plexus, preganglionic autonomic nerves, and skeletal, cardiac, and smooth muscle neuromuscular junctions. These mice should be useful for in vivo studies of cholinergic neurotransmission and neuromuscular coupling. Moreover, this genetic strategy allows the selective expression and conditional inactivation of genes of interest in cholinergic nerves of the central nervous system and peripheral nervous system.
Detection of SNP epistasis effects of quantitative traits using an extended Kempthorne model
Authors: Mao Yongcai , London Nicole R. , Ma Li , Dvorkin Daniel , Da Yang
Published: August 2006

Epistasis effects (gene interactions) have been increasingly recognized as important genetic factors underlying complex traits. The existence of a large number of single nucleotide polymorphisms (SNPs) provides opportunities and challenges to screen DNA variations affecting complex traits using a candidate gene analysis. In this article, four types of epistasis effects of two candidate gene SNPs with Hardy-Weinberg disequilibrium (HWD) and linkage disequilibrium (LD) are considered: additive × additive, additive × dominance, dominance × additive, and dominance × dominance. The Kempthorne genetic model was chosen for its appealing genetic interpretations of the epistasis effects. The method in this study consists of extension of Kempthorne's definitions of 35 individual genetic effects to allow HWD and LD, genetic contrasts of the 35 extended individual genetic effects to define the 4 epistasis effects, and a linear model method for testing epistasis effects. Formulas to predict statistical power (as a function of contrast heritability, sample size, and type I error) and sample size (as a function of contrast heritability, type I error, and type II error) for detecting each epistasis effect were derived, and the theoretical predictions agreed well with simulation studies. The accuracy in estimating each epistasis effect and rates of false positives in the absence of all or three epistasis effects were evaluated using simulations. The method for epistasis testing can be a useful tool to understand the exact mode of epistasis, to assemble genome-wide SNPs into an epistasis network, and to assemble all SNP effects affecting a phenotype using pairwise epistasis tests.
Genomic dissection of mucosal immunobiology in the porcine small intestine
Authors: Dvorak Cheryl M. T. , Hirsch Geoffrey N. , Hyland Kendra A. , Hendrickson Julie A. , Thompson Beth S. , Rutherford Mark S. , Murtaugh Michael P.
Published: August 2006

The enteric immune system of swine protects against infectious and noninfectious environmental insults and discriminates ingested nutrients, food, and commensal microflora from pathogenic agents. The molecular and cellular elements of the immune system have been selected over evolutionary time in response to the specific environment of pigs. Thus, models of immune function based on mouse and human need to be applied cautiously in the pig. To better understand how the mucosal immune system of the small intestine accomplishes the conflicting functions of food tolerance and immunity to enteric infection, we used a genomic approach to profile gene expression in the Peyer's patch. More than 40% of mRNA enriched by differential subtraction for Peyer's patch-specific expressed sequences represented genes of unknown function or had no match in GenBank. Microarray analysis and radiation hybrid mapping validated their porcine origin and provided additional insights into putative functions. The abundance of expressed genes of unknown function indicates that a substantial fraction of the immunological and physiological processes of the Peyer's patch remains to be discovered. It further suggests that swine have evolved specialized biochemical and immunological processes in the small intestine. Further elucidation of these processes are expected to provide novel insights into swine enteric mucosal immune function.
Synectin-dependent gene expression in endothelial cells
Authors: Lanahan Anthony A. , Chittenden Thomas W. , Mulvihill Eileen , Smith Kimberly , Schwartz Stephen , Simons Michael
Published: August 2006

Synectin (GIPC1), a receptor scaffold protein, has been isolated by our laboratory as a syndecan-4 cytoplasmic domain binding partner that regulates important aspects of cell motility (Gao Y, Li M, Chen W, Simons M. J Cell Physiol 184: 373–379, 2000; Tkachenko E, Elfenbein A, Tirziu D, Simons M. Circ Res 98: 1398–1404, 2006). Moreover, synectin plays a major role in arterial morphogenesis and in growth factor signaling in arterial endothelial cells by regulating Rac1 activity (Chittenden TW, Claes F, Lanahan AA, Autiero M, Palac RT, Tkachenko EV, Elfenbein A, Ruiz de Almodovar C, Dedkov E, Tomanek R, Li W, Westmore M, Singh J, Horowitz A, Mulligan-Kehoe MJ, Moodie KL, Zhuang ZW, Carmeliet P, Simons M. Dev Cell 10: 783–795, 2006). The present study was carried out to characterize changes in synectin-dependent gene expression induced by homozygous disruption of the gene in endothelial cells. Using a combination of suppression subtraction hybridization and high throughput microarray technology, we have identified aberrant biological processes of transcriptional regulation in synectin−/−primary endothelial cells including abnormal basal regulation of genes associated with development, cell organization and biogenesis, intracellular tracking, and cell adhesion. Analysis of gene expression following FGF2 treatment demonstrated significant abnormalities in transcription, cytoskeletal organization and biogenesis, and protein modification and transport in synectin−/−compared with synectin+/+endothelial cells. These results confirm synectin involvement in FGF2-dependent signal transduction and provide insights into synectin-dependent gene expression in the endothelium.
Epidemiology and Outcomes of Pediatric Traumatic Brain Injury
Authors: Keenan Heather T. , Bratton Susan L.
Published: August 2006

Traumatic brain injury is a leading cause of death and disability in the pediatric age group. Causes of injury vary with child developmental age, with more inflicted injuries in infants, fall-related injuries among toddlers, sports-related injuries among middle-school-aged children and motor vehicle crashes in older children. Prevention strategies exist for some pediatric traumatic brain injury; however, all suffer from lack of compliance and enforcement. Neuropsychological and behavioral outcomes for injured children vary with the severity of injury, child age at injury, premorbid child characteristics, family factors and the families’ socioeconomic status. Each of these factors needs to be taken into account when designing rehabilitation strategies and assessing factors related to outcome.
Clinical Trials in Pediatric Traumatic Brain Injury: Unique Challenges and Potential Responses
Authors: Natale JoAnne E. , Joseph Jill G. , Pretzlaff Robert K. , Silber Tomas J. , Guerguerian Anne-Marie
Published: August 2006

In order to optimize pediatric traumatic brain injury translational and clinical research, scientific and ethical challenges need to be recognized and addressed. Having recently conducted a multisite phase II safety/feasibility trial of magnesium sulfate as a neuroprotective agent, we supplement our own experience by a mini review of similar studies, identifying challenges and possible responses from the perspective of families, investigators, funding agencies and society.
Use of Advanced Neuroimaging Techniques in the Evaluation of Pediatric Traumatic Brain Injury
Authors: Ashwal Stephen , Holshouser Barbara A. , Tong Karen A.
Published: August 2006

Advanced neuroimaging techniques are now used to expand our knowledge of traumatic brain injury, and increasingly, they are being applied to children. This review will examine four of these methods as they apply to children who present acutely after injury. (1) Susceptibility weighted imaging is a 3-dimensional high-resolution magnetic resonance imaging technique that is more sensitive than conventional imaging in detecting hemorrhagic lesions that are often associated with diffuse axonal injury. (2) Magnetic resonance spectroscopyacquires metabolite information reflecting neuronal integrity and function from multiple brain regions and provides sensitive, noninvasive assessment of neurochemical alterations that offers early prognostic information regarding the outcome. (3) Diffusion weighted imaging is based on differences in diffusion of water molecules within the brain and has been shown to be very sensitive in the early detection of ischemic injury. It is now being used to study the direct effects of traumatic injury as well as those due to secondary ischemia. (4) Diffusion tensor imaging is a form of diffusion weighted imaging and allows better evaluation of white matter fiber tracts by taking advantage of the intrinsic directionality (anisotropy) of water diffusion in human brain. It has been shown to be useful in identifying white matter abnormalities after diffuse axonal injury when conventional imaging appears normal. An important aspect of these advanced methods is that they demonstrate that ‘normal-appearing’ brain in many instances is not normal, i.e. there is evidence of significant undetected injury that may underlie a child’s clinical status. Availability and integration of these advanced imaging methods will lead to better treatment and change the standard of care for use of neuroimaging to evaluate children with traumatic brain injury.
Serum Biomarkers after Traumatic and Hypoxemic Brain Injuries: Insight into the Biochemical Response of the Pediatric Brain to Inflicted Brain Injury
Authors: Pardes Berger Rachel , Adelson P. David , Richichi Rudolph , Kochanek Patrick M.
Published: August 2006

Inflicted traumatic brain injury (iTBI) involves a combination of mechanical trauma and hypoxemia. Serum biomarker concentrations may provide objective information about their relative importance to the pathophysiology of iTBI. We compared the time course of neuron-specific enolase (NSE), S100B and myelin basic protein after pediatric hypoxic-ischemic brain injury, iTBI and noninflicted TBI (nTBI). The time to reach peak concentrations of all three biomarkers was shorter after nTBI. Initial and peak S100B, initial and peak myelin basic protein and peak NSE concentrations were no different between the three groups. Initial NSE concentration was highest after nTBI. These results suggest that the biochemical response of the brain to iTBI is distinct from the response to nTBI and shares temporal similarities with hypoxic-ischemic brain injury. This may have important implications for the treatment and prognosis of children with iTBI.