bluuebunny/crossref_metadata_2025 huggingface dataset:
Age-Related Effects on Nelfinavir and M8 Pharmacokinetics: a Population Study with 182 Children
Authors: Hirt Déborah , Urien Saïk , Jullien Vincent , Firtion Ghislaine , Rey Elisabeth , Pons Gérard , Blanche Stéphane , Treluyer Jean-Marc
Published: February 2006

As a relationship between nelfinavir antiretroviral efficacy and plasma concentrations has been previously established, nelfinavir pharmacokinetics was investigated in order to optimize the individual treatment schedule in a pediatric population. A population pharmacokinetic model was developed to describe the concentration-time course of nelfinavir and its active metabolite M8. Individual characteristics were used to explain the large interindividual variability in children. Data from therapeutic drug monitoring in 182 children treated with nelfinavir were analyzed with NONMEM. Then Food and Drug Administration (FDA) current recommendations were evaluated estimating the percentage of children who reached the target minimum plasma concentration (0.8 mg/liter) by using Bayesian estimates. Nelfinavir pharmacokinetics was described by a one- compartment model with linear absorption and elimination. Pharmacokinetic estimates and the corresponding intersubject variabilities for the model were as follows: nelfinavir total clearance, 0.93 liters/h/kg (39%); volume of distribution, 6.9 liters/kg (109%); absorption rate, 0.5 h−1; formation clearance fraction to hydroxy-tert-butylamide (M8), 0.025; M8 elimination rate, 1.88 h−1(49%). Apparent nelfinavir total clearance and volume of distribution decreased as a function of age. M8 elimination rate was increased by concomitant administration of nevirapine or efavirenz. Our data confirm that the FDA recommendations for children from 2 to 13 years are optimal and that the dose recommended for children younger than 2 years is adequate for the children from 2 months to 2 years old. However, in children younger than 2 months, the proposed nelfinavir newborn dose of 40 mg/kg of body weight twice daily is inadequate and we suggest increasing the dose to 50 to 60 mg/kg administered thrice daily. This assumption should be further evaluated.
Artesunate Suppositories versus Intramuscular Artemether for Treatment of Severe Malaria in Children in Papua New Guinea
Authors: Karunajeewa Harin A. , Reeder John , Lorry Kerry , Dabod Elizah , Hamzah Juliana , Page-Sharp Madhu , Chiswell Gregory M. , Ilett Kenneth F. , Davis Timothy M. E.
Published: February 2006

Drug treatment of severe malaria must be rapidly effective. Suppositories may be valuable for childhood malaria when circumstances prevent oral or parenteral therapy. We compared artesunate suppositories (n= 41; 8 to 16 mg/kg of body weight at 0 and 12 h and then daily) with intramuscular (i.m.) artemether (n= 38; 3.2 mg/kg at 0 h and then 1.6 mg/kg daily) in an open-label, randomized trial with children with severePlasmodium falciparummalaria in Papua New Guinea (PNG). Parasite density and temperature were measured every 6 h for ≥72 h. Primary endpoints included times to 50% and 90% parasite clearance (PCT50and PCT90) and the time to per os status. In a subset of 29 patients, plasma levels of artemether, artesunate, and their common active metabolite dihydroartemisinin were measured during the first 12 h. One suppository-treated patient with multiple complications died within 2 h of admission, but the remaining 78 recovered uneventfully. Compared to the artemether-treated children, those receiving artesunate suppositories had a significantly earlier mean PCT50(9.1 versus 13.8 h;P= 0.008) and PCT90(15.6 versus 20.4 h;P= 0.011). Mean time to per os status was similar for each group. Plasma concentrations of primary drug plus active metabolite were significantly higher in the artesunate suppository group at 2 h postdose. The earlier initial fall in parasitemia with artesunate is clinically advantageous and mirrors higher initial plasma concentrations of active drug/metabolite. In severely ill children with malaria in PNG, artesunate suppositories were at least as effective as i.m. artemether and may, therefore, be useful in settings where parenteral therapy cannot be given.
Involvement of the HP0165-HP0166 Two-Component System in Expression of Some Acidic-pH-Upregulated Genes of
Helicobacter pylori
Authors: Wen Yi , Feng Jing , Scott David R. , Marcus Elizabeth A. , Sachs George
Published: February 2006

About 200 genes of the gastric pathogen
Helicobacter pylori
increase expression at medium pHs of 6.2, 5.5, and 4.5, an increase that is abolished or much reduced by the buffering action of urease. Genes up-regulated by a low pH include the two-component system HP0165-HP0166, suggesting a role in the regulation of some of the pH-sensitive genes. To identify targets of HP0165-HP0166, the promoter regions of genes up-regulated by a low pH were grouped based on sequence similarity. Probes for promoter sequences representing each group were subjected to electrophoretic mobility shift assays (EMSA) with recombinant HP0166-His
6
or a mutated response regulator, HP0166-D52N-His
6
, that can specifically determine the role of phosphorylation of HP0166 in binding (including a control EMSA with in-vitro-phosphorylated HP0166-His
6
). Nineteen of 45 promoter-regulatory regions were found to interact with HP0166-His
6
. Seven promoters for genes encoding α-carbonic anhydrase,
omp11
,
fecD
,
lpp20
,
hypA
, and two with unknown function (
p
HP1397-1396 and
p
HP0654-0675) were clustered in gene group A, which may respond to changes in the periplasmic pH at a constant cytoplasmic pH and showed phosphorylation-dependent binding in EMSA with HP0166-D52N-His
6
. Twelve promoters were clustered in groups B and C whose up-regulation likely also depends on a reduction of the cytoplasmic pH at a medium pH of 5.5 or 4.5. Most of the target promoters in groups B and C showed phosphorylation-dependent binding with HP0166-D52N-His
6
, but promoters for
ompR
(p
HP0166
-
0162
), p
HP0682
-
0681
, and p
HP1288
-
1289
showed phosphorylation-independent binding. These findings, combined with DNase I footprinting, suggest that HP0165-0166 is an acid-responsive signaling system affecting the expression of pH-sensitive genes. Regulation of these genes responds either to a decrease in the periplasmic pH alone (HP0165 dependent) or also to a decrease in the cytoplasmic pH (HP0165 independent).
Gene Products Required for De Novo Synthesis of Polysialic Acid in
Escherichia coli
K1
Authors: Andreishcheva Ekaterina N. , Vann Willie F.
Published: February 2006

Escherichia coli
K1 is responsible for 80% of
E. coli
neonatal meningitis and is a common pathogen in urinary tract infections. Bacteria of this serotype are encapsulated with the α(2-8)-polysialic acid NeuNAc(α2-8), common to several bacterial pathogens. The gene cluster encoding the pathway for synthesis of this polymer is organized into three regions: (i)
kpsSCUDEF
, (ii)
neuDBACES
, and (iii)
kpsMT
. The K1 polysialyltransferase, NeuS, cannot synthesize polysialic acid de novo without other products of the gene cluster. Membranes isolated from strains having the entire K1 gene cluster can synthesize polysialic acid de novo. We designed a series of plasmid constructs containing fragments of regions 1 and 2 in two compatible vectors to determine the minimum number of gene products required for de novo synthesis of the polysialic acid from CMP-NeuNAc in K1
E. coli
. We measured the ability of the various combinations of region 1 and 2 fragments to restore polysialyltransferase activity in vitro in the absence of exogenously added polysaccharide acceptor. The products of region 2 genes
neuDBACES
alone were not sufficient to support de novo synthesis of polysialic acid in vitro. Only membrane fractions harboring NeuES and KpsCS could form sialic polymer in the absence of exogenous acceptor at the concentrations formed by wild-type
E. coli
K1 membranes. Membrane fractions harboring NeuES and KpsC together could form small quantities of the sialic polymer de novo.
Epistasis Analysis of Four Genes from
Anabaena
sp. Strain PCC 7120 Suggests a Connection between PatA and PatS in Heterocyst Pattern Formation
Authors: Orozco Christine C. , Risser Douglas D. , Callahan Sean M.
Published: February 2006

The
hetR
,
patA
,
hetN
, and
patS
genes are part of a regulatory network that regulates the differentiation and patterning of heterocysts in the filamentous cyanobacterium
Anabaena
sp. strain PCC 7120. In this report, the epistatic interactions of mutant alleles of these four genes have been used to refine our understanding of their relationships to one another. The
hetR
gene was necessary for differentiation in genetic backgrounds that normally give rise to excessive differentiation, supporting its role as the master regulator of differentiation and indicating that HetR directly regulates factors in addition to
hetR
and
patS
genes that regulate differentiation. A functional
patS
gene was necessary for the delayed multiple-contiguous-heterocyst phenotype observed in
hetN
mutants as well as for the relative lack of intercalary heterocysts in
patA
mutants. Epistasis results with mutant alleles of these three genes suggested that PatA attenuates the negative effects of both PatS and HetN on differentiation and promotes differentiation independent of its antagonistic effects on PatS and HetN activity. Cooverxpression of
patS
and
hetR
in a synthetic operon indicated that
patS
acts at a point downstream of
hetR
transcription in the regulatory network controlling differentiation. A model for the regulation of differentiation that is consistent with these and previous findings is presented.
Global Analysis of Heat Shock Response in
Desulfovibrio vulgaris
Hildenborough
Authors: Chhabra S. R. , He Q. , Huang K. H. , Gaucher S. P. , Alm E. J. , He Z. , Hadi M. Z. , Hazen T. C. , Wall J. D. , Zhou J. , Arkin A. P. , Singh A. K.
Published: February 2006

Desulfovibrio vulgaris
Hildenborough belongs to a class of sulfate-reducing bacteria (SRB) and is found ubiquitously in nature. Given the importance of SRB-mediated reduction for bioremediation of metal ion contaminants, ongoing research on
D. vulgaris
has been in the direction of elucidating regulatory mechanisms for this organism under a variety of stress conditions. This work presents a global view of this organism's response to elevated growth temperature using whole-cell transcriptomics and proteomics tools. Transcriptional response (1.7-fold change or greater; Z ≥ 1.5) ranged from 1,135 genes at 15 min to 1,463 genes at 120 min for a temperature up-shift of 13°C from a growth temperature of 37°C for this organism and suggested both direct and indirect modes of heat sensing. Clusters of orthologous group categories that were significantly affected included posttranslational modifications; protein turnover and chaperones (up-regulated); energy production and conversion (down-regulated), nucleotide transport, metabolism (down-regulated), and translation; ribosomal structure; and biogenesis (down-regulated). Analysis of the genome sequence revealed the presence of features of both negative and positive regulation which included the CIRCE element and promoter sequences corresponding to the alternate sigma factors σ
32
and σ
54
. While mechanisms of heat shock control for some genes appeared to coincide with those established for
Escherichia coli
and
Bacillus subtilis
, the presence of unique control schemes for several other genes was also evident. Analysis of protein expression levels using differential in-gel electrophoresis suggested good agreement with transcriptional profiles of several heat shock proteins, including DnaK (DVU0811), HtpG (DVU2643), HtrA (DVU1468), and AhpC (DVU2247). The proteomics study also suggested the possibility of posttranslational modifications in the chaperones DnaK, AhpC, GroES (DVU1977), and GroEL (DVU1976) and also several periplasmic ABC transporters.
Antibiotic Inducibility of the MexXY Multidrug Efflux System of
Pseudomonas aeruginosa
: Involvement of the Antibiotic-Inducible PA5471 Gene Product
Authors: Morita Yuji , Sobel Mara L. , Poole Keith
Published: February 2006

The MexXY components of the MexXY-OprM multidrug efflux system of
Pseudomonas aeruginosa
are encoded by a MexZ repressor-regulated operon that is inducible by antibiotics that target the ribosome. Mutant strains disrupted in a gene, PA5471, were shown to be compromised for drug-inducible
mexXY
expression and, therefore, MexXY-OprM-mediated antimicrobial resistance. The PA5471 gene was inducible by the same ribosome-targeting agents that induce
mexXY
expression. Moreover, vector-driven expression of cloned PA5471 was sufficient to promote
mexXY
expression and MexXY-mediated resistance in the absence of antibiotic exposure, consistent with PA5471 directly or indirectly activating
mexXY
expression following its own upregulation in response to antibiotics. The requirement for PA5471 for
mexXY
expression and antimicrobial resistance was, however, obviated in mutants lacking the MexZ repressor of
mexXY
expression, suggesting that PA5471 directly or indirectly modulates MexZ activity in effecting
mexXY
expression. While the recruitment of PA5471 and MexXY in response to ribosome disruption by antimicrobials is consistent with their genes playing a role in protecting cells from the adverse consequences of disrupting the translation process, reminiscent of
trans
-translation, these genes appear to operate independently in their contribution to resistance: mutants defective in
trans
-translation showed a much more modest (twofold) decrease in resistance to ribosome-targeting agents than those lacking PA5471 or MexXY, and this decrease was observed whether functional PA5471/MexXY was present or not.
Overexpression of
tnaC
of
Escherichia coli
Inhibits Growth by Depleting tRNA
2
Pro
Availability
Authors: Gong Ming , Gong Feng , Yanofsky Charles
Published: February 2006

Transcription of the tryptophanase (
tna
) operon of
Escherichia coli
is regulated by catabolite repression and tryptophan-induced transcription antitermination. Induction results from ribosome stalling after translation of
tnaC
, the coding region for a 24-residue leader peptide. The last sense codon of
tnaC
, proline codon 24 (CCU), is translated by tRNA
2
Pro
. We analyzed the consequences of overexpression of
tnaC
from a multicopy plasmid and observed that under inducing conditions more than 60% of the tRNA
2
Pro
in the cell was sequestered in ribosomes as TnaC-tRNA
2
Pro
. The half-life of this TnaC-tRNA
2
Pro
was shown to be 10 to 15 min under these conditions. Plasmid-mediated overexpression of
tnaC
, under inducing conditions, reduced cell growth rate appreciably. Increasing the tRNA
2
Pro
level relieved this growth inhibition, suggesting that depletion of this tRNA was primarily responsible for the growth rate reduction. Growth inhibition was not relieved by overexpression of tRNA
1
Pro
, a tRNA
Pro
that translates CCG, but not CCU. Replacing the Pro24CCU codon of
tnaC
by Pro24CCG, a Pro codon translated by tRNA
1
Pro
, also led to growth rate reduction, and this reduction was relieved by overexpression of tRNA
1
Pro
. These findings establish that the growth inhibition caused by
tnaC
overexpression during induction by tryptophan is primarily a consequence of tRNA
Pro
depletion, resulting from TnaC-tRNA
Pro
retention within stalled, translating ribosomes.
Borrelia burgdorferi ftsZ
Plays a Role in Cell Division
Authors: Dubytska Lydia , Godfrey Henry P. , Cabello Felipe C.
Published: February 2006

ftsZ
is essential for cell division in many microorganisms. In
Escherichia coli
and
Bacillus subtilis
, FtsZ plays a role in ring formation at the leading edge of the cell division septum. An
ftsZ
homologue is present in the
Borrelia burgdorferi
genome (

ftsZ
Bbu

). Its gene product (FtsZ
Bbu
) is strongly homologous to other bacterial FtsZ proteins, but its function has not been established. Because loss-of-function mutants of

ftsZ
Bbu

might be lethal, the
tetR/tetO
system was adapted for regulated control of this gene in
B. burgdorferi
. Sixty-two nucleotides of an

ftsZ
Bbu

antisense DNA sequence under the control of a tetracycline-responsive modified hybrid borrelial promoter were cloned into pKFSS1. This construct was electroporated into a
B. burgdorferi
host strain carrying a chromosomally located
tetR
under the control of the
B. burgdorferi flaB
promoter. After induction by anhydrotetracycline, expression of antisense
ftsZ
RNA resulted in generation of filamentous
B. burgdorferi
that were unable to divide and grew more slowly than uninduced cells. To determine whether FtsZ
Bbu
could interfere with the function of
E. coli
FtsZ,

ftsZ
Bbu

was amplified from chromosomal DNA and placed under the control of the tetracycline-regulated hybrid promoter. After introduction of the construct into
E. coli
and induction with anhydrotetracycline, overexpression of

ftsZ
Bbu

generated a filamentous phenotype. This suggested interference of

ftsZ
Bbu

with
E. coli
FtsZ function and confirmed the role of

ftsZ
Bbu

in cell division. This is the first report of the generation of a
B. burgdorferi
conditional lethal mutant equivalent by tetracycline-controlled expression of antisense RNA.
MECHANISM OF LEAF-SHAPE DETERMINATION
Authors: Tsukaya Hirokazu
Published: February 2006

Biodiversity of plant shape is mainly attributable to biodiversity of leaf shape and the shape of floral organs, the modified leaves. However, the exact mechanisms of leaf-shape determination remain unclear due to the complexity of flat-structure organogenesis that includes the simultaneous cell cycling and cell enlargement in primordia. Recent studies in developmental and molecular genetics have revealed several important aspects of leaf-shape control mechanisms. For example, understanding of polar control in leaf-blade expansion has advanced greatly. A curious phenomenon called “compensated cell enlargement” found in leaf organogenesis studies should also provide interesting clues regarding the mechanisms of multicellular organ development. This paper reviews recent research findings with a focus on leaf development in Arabidopsis thaliana.
Energy Transduction: Proton Transfer Through the Respiratory Complexes
Authors: Hosler Jonathan P. , Ferguson-Miller Shelagh , Mills Denise A.
Published: February 2006

A series of metalloprotein complexes embedded in a mitochondrial or bacterial membrane utilize electron transfer reactions to pump protons across the membrane and create an electrochemical potential (ΔμH+). Current understanding of the principles of electron-driven proton transfer is discussed, mainly with respect to the wealth of knowledge available from studies of cytochrome c oxidase. Structural, experimental, and theoretical evidence supports the model of long-distance proton transfer via hydrogen-bonded water chains in proteins as well as the basic concept that proton uptake and release in a redox-driven pump are driven by charge changes at the membrane-embedded centers. Key elements in the pumping mechanism may include bound water, carboxylates, and the heme propionates, arginines, and associated water above the hemes. There is evidence for an important role of subunit III and proton backflow, but the number and nature of gating mechanisms remain elusive, as does the mechanism of physiological control of efficiency.
Tagging and tracking individual networks within a complex mitochondrial web with photoactivatable GFP
Authors: Twig Gilad , Graf Solomon A. , Wikstrom Jakob D. , Mohamed Hibo , Haigh Sarah E. , Elorza Alvaro , Deutsch Motti , Zurgil Naomi , Reynolds Nicole , Shirihai Orian S.
Published: February 2006

Assembly of mitochondria into networks supports fuel metabolism and calcium transport and is involved in the cellular response to apoptotic stimuli. A mitochondrial network is defined as a continuous matrix lumen whose boundaries limit molecular diffusion. Observation of individual networks has proven challenging in live cells that possess dense populations of mitochondria. Investigation into the electrical and morphological properties of mitochondrial networks has therefore not yielded consistent conclusions. In this study we used matrix-targeted, photoactivatable green fluorescent protein to tag single mitochondrial networks. This approach, coupled with real-time monitoring of mitochondrial membrane potential, permitted the examination of matrix lumen continuity and fusion and fission events over time. We found that adjacent and intertwined mitochondrial structures often represent a collection of distinct networks. We additionally found that all areas of a single network are invariably equipotential, suggesting that a heterogeneous pattern of membrane potential within a cell's mitochondria represents differences between discrete networks. Interestingly, fission events frequently occurred without any gross morphological changes and particularly without fragmentation. These events, which are invisible under standard confocal microscopy, redefine the mitochondrial network boundaries and result in electrically disconnected daughter units.
Distribution of sodium transporters and aquaporin-1 in the human choroid plexus
Authors: Praetorius Jeppe , Nielsen Søren
Published: February 2006

The choroid plexus epithelium secretes electrolytes and fluid in the brain ventricular lumen at high rates. Several channels and ion carriers have been identified as likely mediators of this transport in rodent choroid plexus. This study aimed to map several of these proteins to the human choroid plexus. Immunoperoxidase-histochemistry was employed to determine the cellular and subcellular localization of the proteins. The water channel, aquaporin (AQP) 1, was predominantly situated in the apical plasma membrane domain, although distinct basolateral and endothelial immunoreactivity was also observed. The Na+-K+-ATPase α1-subunit was exclusively localized apically in the human choroid plexus epithelial cells. Immunoreactivity for the Na+-K+-2Cl− cotransporter, NKCC1, was likewise confined to the apical plasma membrane domain of the epithelium. The Cl−/HCO3− exchanger, AE2, was localized basolaterally, as was the Na+-dependent Cl−/HCO3− exchanger, NCBE, and the electroneutral Na+-HCO3− cotransporter, NBCn1. No immunoreactivity was found toward the Na+-dependent acid/base transporters NHE1 or NBCe2. Hence, the human choroid plexus epithelium displays an almost identical distribution pattern of water channels and Na+ transporters as the rat and mouse choroid plexus. This general cross species pattern suggests central roles for these transporters in choroid plexus functions such as cerebrospinal fluid production.
Intracerebroventricular C75 decreases meal frequency and reduces AgRP gene expression in rats
Authors: Aja Susan , Bi Sheng , Knipp Susan B. , McFadden Jill M. , Ronnett Gabriele V. , Kuhajda Francis P. , Moran Timothy H.
Published: February 2006

3-Carboxy-4-alkyl-2-methylenebutyrolactone (C75), an inhibitor of fatty acid synthase and stimulator of carnitine palmitoyltransferase-1, reduces food intake and body weight in rodents when given systemically or centrally. Intracellular molecular mechanisms involving changes in cellular energy status are proposed to initiate the feeding and body weight reductions. However, effectors that lie downstream of these initial steps are not yet fully identified. Present experiments characterize the time courses of hypophagia and weight loss after single injections of C75 into the lateral cerebroventicle in rats and go on to identify specific meal pattern changes and coinciding alterations in gene expression for feeding-related hypothalamic neuropeptides. C75 reduced chow intake and body weight dose dependently. Although the principal effects occurred on the first day, weight losses relative to vehicle control were maintained over multiple days. C75 did not affect generalized locomotor activity. C75 began to reduce feeding after a 6-h delay. The hypophagia was due primarily to decreased meal number during 6–12 h without a significant effect on meal size, suggesting that central C75 reduced the drive to initiate meals. C75 prevented the anticipated hypophagia-induced increases in mRNA for AgRP in the arcuate nucleus at 22 h and at 6 h when C75 begins to suppress feeding. Overall, the data suggest that gene expression changes leading to altered melanocortin signaling are important for the hypophagic response to intracerebroventricular C75.
Mechanistic studies of acid-evoked coughing in anesthetized guinea pigs
Authors: Canning Brendan J. , Farmer David G. , Mori Nanako
Published: February 2006

Experiments carried out in conscious guinea pigs suggest that citric acid-evoked coughing is partly mediated by transient receptor potential vanilloid type 1 (TRPV1) receptor-dependent activation of tachykinin-containing, capsaicin-sensitive C fibers. In vitro electrophysiological analyses indicate, however, that acid also activates capsaicin-sensitive and -insensitive vagal afferent nerves by a TRPV1-independent mechanism, and studies in anesthetized guinea pigs show that coughing evoked by acid is mediated by activation of capsaicin-insensitive vagal afferent nerves. In the present study, we have characterized the mechanisms of citric acid-evoked coughing in anesthetized guinea pigs. Drugs were administered directly to the Krebs buffer perfusing the extrathoracic trachea. Citric acid was applied topically to the tracheal mucosa, directly into the tracheal perfusate in increasing concentrations and at 1-min intervals. Citric acid dose dependently evoked coughing in anesthetized guinea pigs. This was mimicked by hydrochloric acid but not by sodium citrate. The coughing evoked by acid was nearly or completely abolished by TTX or by cutting the recurrent laryngeal nerves. Perfusing the trachea with a low Cl− buffer potentiated the acid-induced cough reflex. In contrast, prior capsaicin desensitization, 10 μM capsazepine, Ca2+-free perfusate, 0.1 μM iberiotoxin, 1 μM atropine, 10 μM isoproterenol, 10 μM albuterol, 3 μM indomethacin, 0.1 μM HOE-140, a combination of neurokinin1 (NK1; CP-99994), NK2 (SR-48968), and NK3 (SB-223412) receptor antagonists (0.1 μM each), a combination of histamine H1 (3 μM pyrilamine) and cysLT1 (1 μM ICI-198615) receptor antagonists, superior laryngeal nerve transection, or epithelium removal did not inhibit citric acid-evoked coughing. These and other data indicate that citric acid-evoked coughing in anesthetized guinea pigs is mediated by direct activation of capsaicin-insensitive vagal afferent nerves, perhaps through sequential activation of acid-sensing ion channels and chloride channels.
Caspase activation contributes to endotoxin-induced diaphragm weakness
Authors: Supinski Gerald S. , Callahan Leigh A.
Published: February 2006

Infections produce significant respiratory muscle weakness, but the mechanisms by which inflammation reduces muscle force remain incompletely understood. Recent work suggests that caspase 3 releases actin and myosin from the contractile protein lattice, so we postulated that infections may reduce skeletal muscle force by activating caspase 3. The present experiments were designed to test this hypothesis by determining 1) diaphragm caspase 3 activation in the diaphragm after endotoxin and 2) the effect of a broad-spectrum caspase inhibitor, Z-Val-Ala-Asp(OCH3)-fluoromethylketone (zVAD-fmk), and a selective caspase 3 inhibitor, N-acetyl-Asp-Glu-Val-Asp-al (DEVD-CHO), on endotoxin-induced diaphragm weakness. Caspase 3 activation was assessed by measuring caspase protein levels and by measuring cleavage of a fluorogenic substrate. Diaphragm force was measured in response to electrical stimulation (1–150 Hz). Caspase-mediated spectrin degradation was assessed by Western blotting. Parameters were compared in mice given saline, endotoxin (12 mg/kg ip), endotoxin plus zVAD-fmk (3 mg/kg iv), zVAD-fmk alone, or endotoxin plus DEVD-CHO (3 mg/kg iv). Endotoxin increased diaphragm active caspase 3 protein ( P < 0.003), increased caspase 3 activity ( P < 0.002), increased diaphragm spectrin degradation ( P < 0.001), and reduced diaphragm force ( P < 0.001). Administration of zVAD-fmk or DEVD-CHO prevented endotoxin-induced weakness (e.g., force in response to 150-Hz stimulation was 23.8 ± 1.4, 12.1 ± 1.3, 23.5 ± 0.8, 22.7 ± 1.3, and 24.4 ± 0.8 N/cm2, respectively, for control, endotoxin, endotoxin plus zVAD-fmk, endotoxin plus DEVD-CHO, and zVAD-fmk alone treated groups, P < 0.001). Caspase inhibitors also prevented spectrin degradation. In conclusion, endotoxin administration elicits significant diaphragm caspase 3 activation and caspase-mediated diaphragmatic weakness.
Properties of Propriospinal Neurons in the C3–C4 Segments Mediating Disynaptic Pyramidal Excitation to Forelimb Motoneurons in the Macaque Monkey
Authors: Isa Tadashi , Ohki Yukari , Seki Kazuhiko , Alstermark Bror
Published: February 2006

Candidate propriospinal neurons (PNs) that mediate disynaptic pyramidal excitation to forelimb motoneurons were studied in the C3–C4 segments in anesthetized macaque monkeys ( n = 10). A total of 177 neurons were recorded (145 extracellularly, 48 intracellularly, and 16 both) in laminae VI–VII. Among these, 86 neurons (73 extracellularly, 14 intracellularly and 1 both) were antidromically activated from the forelimb motor nucleus or from the ventrolateral funiculus just lateral to the motor nucleus in the C6/C7 segments and thus are identified as PNs. Among the 73 extracellularly recorded PNs, 60 cells were fired by a train of four stimuli to the contralateral pyramid with segmental latencies of 0.8–2.2 ms, with most of them ( n = 52) in a monosynaptic range (<1.4 ms including one synaptic delay and time to firing). The firing probability was only 21% from the third pyramidal volley but increased to 83% after intravenous injection of strychnine. In most of the intracellularly recorded PNs, stimulation of the contralateral pyramid evoked monosynaptic excitatory postsynaptic potentials (EPSPs, 12/14) and disynaptic inhibitory postsynaptic potentials (14/14), which were found to be glycinergic. In contrast, cells that did not project to the C6–Th1 segments where forelimb motoneurons are located were classified as segmental interneurons. These were fired from the third pyramidal volley with a probability of 71% before injection of strychnine. It is proposed that some of these interneurons mediate feed-forward inhibition to the PNs. These results suggest that the C3–C4 PNs receive feed-forward inhibition from the pyramid in addition to monosynaptic excitation and that this inhibition is stronger in the macaque monkey than in the cat. Another difference with the cat was that only 26 of the 86 PNs (30%, as compared with 84% in the cat) with projection to the forelimb motor nuclei send ascending collaterals terminating in the lateral reticular nucleus (LRN) on the ipsilateral side of the medulla. Thus we identified C3–C4 PNs that could mediate disynaptic pyramidal excitation to forelimb motoneurons in the macaque monkey. The present findings explain why it was difficult in previous studies of the macaque monkey to evoke disynaptic pyramidal excitation via C3–C4 PNs in forelimb motoneurons and why—as compared with the cat—the monosynaptic EPSPs evoked from the LRN via C3–C4 PNs were smaller in amplitude.
Soleus- and Gastrocnemii-Evoked V-Wave Responses Increase After Neuromuscular Electrical Stimulation Training
Authors: Gondin Julien , Duclay Julien , Martin Alain
Published: February 2006

The aim of the study was to use combined longitudinal measurements of soleus (SOL) and gastrocnemii evoked V-wave and H-reflex responses to determine the site of adaptations within the central nervous system induced by 5 wk of neuromuscular electrical stimulation (NMES) training of the plantar flexor muscles. Nineteen healthy males subjects were divided into a neuromuscular electrostimulated group ( n = 12) and a control group ( n = 7). The training program consisted of 15 sessions of isometric NMES over a 5-wk period. All subjects were tested before and after the 5-wk period. SOL, lateral gastrocnemius (LG), and medial gastrocnemius (MG) maximal H-reflex and M-wave potentials were evoked at rest (i.e., Hmax and Mmax, respectively) and during maximal voluntary contraction (MVC) (i.e., Hsup and Msup, respectively). During MVC, a supramaximal stimulus was delivered that allowed us to record the V-wave peak-to-peak amplitudes from all three muscles. The SOL, LG, and MG electromyographic (EMG) activity as well as muscle activation (twitch interpolation technique) were also quantified during MVC. After training, plantar flexor MVC increased significantly by 22% ( P < 0.001). Torque gains were accompanied by an increase in muscle activation (+11%, P < 0.05), SOL, LG, and MG normalized EMG activity (+51, +54, and +60%, respectively, P < 0.05) and V/Msup ratios (+81, +76, and +97%, respectively, P < 0.05). Hmax/Mmax and Hsup/Msup ratios for all three muscles were unchanged after training. In conclusion, the increase in voluntary torque after 5 wk of NMES training could be ascribed to an increased volitional drive from the supraspinal centers and/or adaptations occurring at the spinal level.
Alterations in Burst Firing of Thalamic VPL Neurons and Reversal by Nav1.3 Antisense After Spinal Cord Injury
Authors: Hains Bryan C. , Saab Carl Y. , Waxman Stephen G.
Published: February 2006

We recently showed that spinal cord contusion injury (SCI) at the thoracic level induces pain-related behaviors and increased spontaneous discharges, hyperresponsiveness to innocuous and noxious peripheral stimuli, and enlarged receptive fields in neurons in the ventral posterolateral (VPL) nucleus of the thalamus. These changes are linked to the abnormal expression of Nav1.3, a rapidly repriming voltage-gated sodium channel. In this study, we examined the burst firing properties of VPL neurons after SCI. Adult male Sprague–Dawley rats underwent contusion SCI at the T9 level. Four weeks later, when Nav1.3 protein was upregulated within VPL neurons, extracellular unit recordings were made from VPL neurons in intact animals, those with SCI, and in SCI animals after receiving lumbar intrathecal injections of Nav1.3 antisense or mismatch oligodeoxynucleotides for 4 days. After SCI, VPL neurons with identifiable peripheral receptive fields showed rhythmic oscillatory burst firing with changes in discrete burst properties, and alternated among single-spike, burst, silent, and spindle wave firing modes. Nav1.3 antisense, but not mismatch, partially reversed alterations in burst firing after SCI. These results demonstrate several newly characterized changes in spontaneous burst firing properties of VPL neurons after SCI and suggest that abnormal expression of Nav1.3 contributes to these phenomena.
Galanin and Galanin-Like Peptide Differentially Modulate Neuronal Activities in Rat Arcuate Nucleus Neurons
Authors: Dong Yan , Tyszkiewicz Joanna P. , Fong Tung M.
Published: February 2006

Neuropeptides galanin and galanin-like peptide (GALP) share similar amino acid sequence and presumably interact with the same group of receptors, but they differentially regulate a variety of physiological and pathophysiological processes including metabolism and reproduction. Here we explored the neurophysiological basis of the in vivo differential effect between galanin and GALP by examining galanin and GALP modulation of neuronal activities of neurons in the arcuate nucleus (Arc), a brain region critically involved in energy homeostasis and reproductive function. We demonstrated that galanin and GALP inhibited excitatory and inhibitory postsynaptic currents in a similar way. In contrast, galanin and GALP differentially affected the intrinsic membrane property. In most recorded Arc neurons, galanin perfusion induced significant hyperpolarization of the resting membrane potential, which was not affected by GALP perfusion. In addition, galanin perfusion substantially suppressed the spontaneous spike firing in most Arc neurons, whereas in response to GALP perfusion, about half of the Arc neurons exhibited mild reduction in spontaneous spike firing and the other half showed enhancement. Furthermore, the Arc neurons that had been previously responsive to galanin perfusion no longer responded to galanin if co-applied with GALP, indicating that GALP can physiologically antagonize galanin effect. This differential effect appears to be mediated by G protein within the recorded cell, as the galanin effect on firing rate was abolished when the recorded cell was loaded with GDP-βS, an agent that blocks G protein activity. Taken together, these differential effects of galanin and GALP may provide a neurophysiological mechanism through which galanin and GALP differentially regulate energy balance, reproductive function, and other physiological processes.
Output of Human Motoneuron Pools to Corticospinal Inputs During Voluntary Contractions
Authors: Martin P. G. , Gandevia S. C. , Taylor J. L.
Published: February 2006

This study investigated transmission of corticospinal output through motoneurons over a wide range of voluntary contraction strengths in humans. During voluntary contraction of biceps brachii, motor evoked potentials (MEPs) to transcranial magnetic stimulation of the motor cortex grow up to about 50% maximal force and then decrease. To determine whether the decrease reflects events at a cortical or spinal level, responses to stimulation of the cortex and corticospinal tract (cervicomedullary motor evoked potentials, CMEPs) as well as maximal M-waves (Mmax) were recorded during strong contractions at 50 to 100% maximum. In biceps and brachioradialis, MEPs and CMEPs (normalized to Mmax) evoked by strong stimuli decreased during strong elbow flexions. Responses were largest during contractions at 75% maximum and both potentials decreased by about 25% Mmax during maximal efforts ( P < 0.001). Reductions were smaller with weaker stimuli, but again similar for MEPs and CMEPs. Thus the reduction in MEPs during strong voluntary contractions can be accounted for by reduced responsiveness of the motoneuron pool to stimulation. During strong contractions of the first dorsal interosseous, a muscle that increases voluntary force largely by frequency modulation, MEPs declined more than in either elbow flexor muscle (35% Mmax, P < 0.001). This suggests that motoneuron firing rates are important determinants of evoked output from the motoneuron pool. However, motor cortical output does not appear to be limited at high contraction strengths.
Stimulus for Rapid Ocular Dominance Plasticity in Visual Cortex
Authors: Rittenhouse Cynthia D. , Siegler Beth A. , Voelker Courtney A. , Shouval Harel Z. , Paradiso Michael A. , Bear Mark F.
Published: February 2006

Although it has been known for decades that monocular deprivation shifts ocular dominance in kitten striate cortex, uncertainty persists about the adequate stimulus for deprivation-induced losses of cortical responsiveness. In the current study we compared the effects of 2 days of lid closure and 2 days of monocular blur using an overcorrecting contact lens. Our finding of comparable ocular dominance shifts in visual cortex indicates that deprived-eye response depression is not a result of reduced retinal illumination. The quality rather than the quantity of retinal illumination is the key factor for ocular dominance plasticity. These data have implications for both the mechanism and treatment of amblyopia.
Penile Metastasis from Other Malignancies
Authors: Hızlı Fatih , Berkmen Ferhat
Published: February 2006

Primary penile carcinoma is one of the rarest male genital tract tumors. We rarely encounter this malignancy in Turkey because circumcision is routinely performed as a part of the Islamic tradition. Despite the medical paradox that the penis is rarely affected by metastases, approximately 300 cases have been reported in the literature. The primary lesion is almost 75% of pelvic origin; genitourinary or rectosigmoid primaries and penile metastasis from extrapelvic primaries constitute 25% of other primaries. Furthermore, isolated metastatic penile carcinomas are exceptionally rare. The rarity of the event prompted this study, which describes 10 cases of metastatic tumors of the penis including 7 cases with transitional cell carcinoma of the bladder, and in 1 case each of squamous cell carcinoma of the lung, adenocarcinoma of the prostate and leukemia. The main characteristics of the primary tumor are described, along with the diagnosis, treatment and the outcome of patients.
Treatment of Urethral Syndrome: A Prospective Randomized Study with Nd:YAG Laser
Authors: Costantini Elisabetta , Zucchi Alessandro , Del Zingaro Michele , Mearini Luigi
Published: February 2006

Introduction: The urethral syndrome is characterized by irritative disturbances, the urgency-frequency syndrome and/or pain associated with negative urine cultures. Areas of metaplasic tissue in the trigonal-bladder neck region (trigonitis) are sometimes present. We performed a comparative randomized study to assess the efficacy of side- or end-firing neodymium (Nd):YAG laser surgery in destroying metaplasia and relieving symptoms. Materials and Methods: Between January 1997 and December 2003, 62 consecutive women with the urethral syndrome and squamous metaplasia of the bladder neck-trigone, who were refractory to drugs, were randomly assigned to treatment with end-firing (group A) or side-firing (group B) Nd:YAG laser. Three, 6 and 12 months after surgery all patients underwent a clinical urological examination and cystoscopy. Surgery was considered successful when patients reported they were satisfied with the outcome or stated on the UDI-6 questionnaire that symptoms were reduced by at least 75%. Results: Group A end-firing laser: patients rapidly improved (2–3 weeks) but symptoms worsened within 3 months. At 6–12 months, symptoms had improved in 19% of the 31 patients and remained unchanged or worsened in 81%. Group B side-firing laser: irritative disturbances worsened in the 7–10 days after therapy but markedly improved within 2–3 months. Symptoms significantly improved in 68% of the 28 patients and remained unchanged or worsened in 32%. Results were significantly better after side-firing laser (p < 0.001) and a trend towards improvements emerged as the joule levels rose. At 3 months, cystoscopy and biopsy showed squamous metaplasia was no longer present in patients whose symptoms had improved. Whitish areas were still present in the bladder neck-trigone in patients whose symptoms had remained unchanged or worsened. These patients were retreated. Conclusions: In the treatment of the urethral syndrome the few reports on attempts to restore a normal urothelium by means of diathermocoagulation and cryotherapy have been encouraging. Side-firing laser, which produces necrotic coagulation followed by reconstitution of normal functional epithelium, was significantly more successful than end-firing and was associated with a 78% success rate. These results are encouraging in patients who are usually refractory to medical therapy.
Surgical Approach to Cases with Multiple Renal Arteries in Renal Transplantation
Authors: Bakirtas Hasan , Guvence Necmettin , Eroglu Muzaffer , Ure Murat , Ozok H. Ugur , Karabulut Irfan , Gul Osman , Banli Oktay
Published: February 2006

Aim: To evaluate the effect of multiple renal artery (MRA) presence on the success and complication rate of renal allotransplantation. Patients and Methods: We retrospectively analyzed 187 cases (128 men and 59 women) who were transplanted in our department from 1997 to 2005. 28 of these cases had MRA. Of MRA kidneys, 6 were obtained from cadavers and 22 from live donors. When the types of anastomoses for MRA cases were examined, 4 cases were anastomosed after being connected to the main polar artery with ex vivo bench surgery; the others had in vivo anastomosis. The patients were divided into two groups as single (group 1) and MRA (group 2) groups. Following the transplantation, creatinine levels, ATN ratios, development of hypertension, patient and graft survivals and vascular and urological complications were compared between the two groups. Results: Patient and graft survival rates were compared between the two groups in the first and third post-operative years. In the first year, graft survival rates for groups 1 and 2 were 94.9 and 92.9% respectively, whereas in the third year these were calculated as 88 and 85.7%. Concerning patient survival, first year results for groups 1 and 2 were 92.5 and 89.2%, for the third year these were found to be 84.9 and 82.1%. Mean creatinine levels of both groups were compared in the first and third years. The results for groups 1 and 2 were 1.41 ± 0.37 and 1.46 ± 0.46 mg/dl respectively for the first year. In the third year these were found to be 1.60 ± 0.43 and 1.69 ± 0.49 mg/dl and there was no statistically significant difference between the groups. Vascular and urological complications were observed in only 6 out of 187 cases (3.2%). Conclusions: No significant difference has been observed between single and MRA kidneys considering the success and complication rates of renal allotransplantation.
Age at Onset of Multiple Sclerosis May Be Influenced by Place of Residence during Childhood Rather than Ancestry
Authors: Kennedy J. , O’Connor P. , Sadovnick A.D. , Perara M. , Yee I. , Banwell B.
Published: February 2006

Multiple sclerosis (MS) most commonly affects individuals of Northern European descent who live in countries at high latitude. The relative contributions of ancestry, country of birth and residence as determinants of MS risk have been studied in adult MS, but have not been explored in the pediatric MS population. In this study, we compare the demographics of pediatric- and adult-onset MS patients cared for in Toronto, Ontario, Canada, a multicultural region. The country of birth, residence during childhood, and ancestry were compared for 44 children and 573 adults. Our results demonstrate that although both the pediatric and adult cohorts were essentially born and raised in the same region of Ontario, Canada, children with MS were more likely to report Caribbean, Asian or Middle Eastern ancestry, and were less likely to have European heritage compared with individuals with adult-onset MS. The difference in ancestry between the pediatric and adult MS cohorts can be explained by two hypotheses: (1) individuals raised in a region of high MS prevalence, but whose ancestors originate from regions in which MS is rare, have an earlier age of MS onset, and (2) the place of residence during childhood, irrespective of ancestry, determines lifetime MS risk – a fact that will be reflected in a change in the demographics of the adult MS cohort in our region as Canadian-raised children of recent immigrants reach the typical age of adult-onset MS.
Rho Kinases in Cardiovascular Physiology and Pathophysiology
Authors: Loirand Gervaise , Guérin Patrice , Pacaud Pierre
Published: February 2006

Rho kinases (ROCKs) are the first and the best-characterized effectors of the small G-protein RhoA. In addition to their effect on actin organization, or through this effect, ROCKs have been found to regulate a wide range of fundamental cell functions such as contraction, motility, proliferation, and apoptosis. Abnormal activation of the RhoA/ROCK pathway has been observed in major cardiovascular disorders such as atherosclerosis, restenosis, hypertension, pulmonary hypertension, and cardiac hypertrophy. This review, based on recent molecular, cellular, and animal studies, focuses on the current understanding of ROCK signaling and its roles in cardiovascular physiology and pathophysiology.