bluuebunny/crossref_metadata_2025 huggingface dataset:
Lack of efficacy of low dose oral interferon alfa in symptomatic HIV-1 infection: a randomised, double blind, placebo controlled trial.
Authors: Katabira E T , Sewankambo N K , Mugerwa R D , Belsey E M , Mubiru F X , Othieno C , Kataaha P , Karam M , Youle M , Perriens J H , Lange J M
Published: January 2009

BACKGROUND: Interferon alfa (IFN-alpha) exhibits dose related in vitro activity against human immunodeficiency virus (HIV), with complete inhibition of HIV replication at IFN-alpha concentrations > or = 256 IU/ml. In mid-1990, Kenyan investigators reported that oral administration of an extremely low dose (150 IU/day) of natural human (nHu) IFN-alpha resulted in complete alleviation of AIDS related complex and AIDS symptoms and resolution of opportunistic infections without additional treatment. Moreover, loss of HIV antibody seropositivity was reported in approximately 10% of treated patients. Subsequent small studies failed to substantiate these spectacular claims, but controversy on the efficacy of this treatment persisted. METHODS: We studied 559 adult Ugandan patients with WHO stage 2-4 HIV infection and a Karnofsky performance score of more than 50, who had not received any drugs with antiretroviral activity in the previous 3 months. The patients were randomly assigned in a double blind fashion either to 150 IU oral nHuIFN-alpha/day or placebo. The duration of treatment was extended from 28 weeks to 60 weeks 9 months after enrollment had started. At that time 112 subjects had already received 28 weeks of treatment and been discontinued from the study. RESULTS: Both study groups were comparable with respect to all baseline characteristics studied, except that the nHuIFN-alpha group had slightly lower absolute CD4+ lymphocyte counts (median 60.7 x 10(6)/l) than the placebo group (median 85.3 x 10(6)/l) (p = 0.033). Therefore, all analyses were adjusted for CD4+ lymphocyte counts at entry. In both treatment groups there was relentless progression of HIV disease. Subjects treated with nHuIFN-alpha and placebo had similar mortality, disease progression rates, decline of CD4+ lymphocyte counts and Karnofsky performance scores, and prevalence of symptoms. No patient reverted to HIV-1 seronegative antibody status. Serious adverse events were not seen. Quality control of the study medication documented that the active drug indeed contained IFN-alpha activity. CONCLUSIONS: The current large, randomised, double blind, placebo controlled study did not show any benefit from oral treatment with 150 IU nHuIFN-alpha/day in a population of African patients with symptomatic HIV infection.
Influence of genital infection on cervical cytology.
Authors: Edwards S K , Sonnex C
Published: January 2009

OBJECTIVE: To ascertain whether the presence of genital infection adversely affects smear quality. METHOD: A prospective study of all patients having cytology performed. The presence of genital infection was recorded and compared with the smear result. RESULTS: The presence of genital infection was not associated with inadequate cytology. Inflammatory changes were found in association with symptomatic candidiasis, trichomoniasis, Chlamydia trachomatis infection, primary herpes simplex, and the finding of 21-30 polymorphs per high power field (averaged over 10 fields) on cervical samples. Inadequate cytology was significantly associated with the smear taker. CONCLUSION: The presence of genital infection at the time of cytology does not increase the rates of inadequacy, and opportunistic cytology should not be deferred as the patient may default from further appointments.
Randomised double blind trial of EMLA for the control of pain related to cryotherapy in the treatment of genital HPV lesions.
Authors: Mansell-Gregory M , Romanowski B
Published: January 2009

OBJECTIVE: To evaluate the efficacy of EMLA (eutectic mixture of local anaesthetic) for the control of pain related to cryotherapy for the treatment of human papilloma virus (HPV) in the outpatient setting. DESIGN: A randomised, double blind, placebo controlled study. SUBJECTS: 40 patients (20 male and 20 female) with external genital HPV involving an area of no greater than 1 cm2. SETTING: The Capital Health Sexually Transmitted Disease Clinic, Edmonton, Alberta, Canada. RESULTS: Patients in whom EMLA was utilised reported significantly lower scores than those in the control group. Women reported pain scores of 4.7/10 and 0.9/10 in placebo and EMLA groups respectively (p < 0.01). Men reported pain scores of 6.4/10 and 3.1/10 in placebo and EMLA groups respectively (p < 0.01). Men reported significantly higher pain scores than women in the EMLA groups (p < 0.01). There was no significant difference in pain scores between men and women in the placebo groups. CONCLUSION: EMLA can provide efficacious topical anaesthesia before cryotherapy for the treatment of external genital HPV.
Isolation and characterisation of T lymphocytes from the urethra of patients with acute urethritis.
Authors: Brunst M , Shahmanesh M , Sukthankar A , Pearce J H , Gaston J S
Published: January 2009

OBJECTIVES: To investigate local cellular immune responses in patients with acute urethritis. METHODS: We have established T cell lines from the urethral exudate and examined their phenotype by flow cytometry. As controls, T cell lines were cultured from first pass urine specimens of asymptomatic healthy individuals. RESULTS: Using interleukin 2 (IL-2) alone a T cell line was obtained on only one occasion. Following culture with IL-2, and subsequent expansion by a single stimulation with irradiated allogenic peripheral blood mononuclear cells (PBMC), phytohaemagglutinin (PHA), and IL-2, it was possible to establish T cell lines from 6/6 acute urethritis patients. T cell lines were also obtained from 4/12 controls subjects, but required repetitive rounds of stimulation with mitogen and allogeneic PBMC to produce sufficient cell numbers for analysis. Three of the patient T cell lines were dominated by T cells expressing the gamma delta receptor. CONCLUSION: The gamma delta T cell subset has been associated with immune responses at mucosal surfaces and has the ability to recognise certain bacterial antigens. The gamma delta T cell response may represent an important aspect of the immune response to organisms associated with acute urethritis.
Prospective cohort study of female sex workers and the risk of HIV infection in Alicante, Spain (1986-96).
Authors: Vioque J , Hernández-Aguado I , Fernandez García E , García de la Hera M , Alvarez-Dardet C
Published: January 2009

OBJECTIVE: To measure the incidence of HIV infection over a 10 year follow up in a cohort of female commercial sex workers in Alicante (Spain), and to determine factors associated with high risk of infection. METHODS: A prospective cohort study was carried in an AIDS information and prevention centre in Alicante, Spain. Of the 1388 female sex workers who initially sought the services of the centre since September 1986, 657 completed at least one additional follow up visit before December 1996. Main outcome measures were infection with HIV-1 and reported risk behaviours. RESULTS: During 1815 person years of observation among 657 female sex workers who were free of HIV infection (negative test), 16 women developed of HIV infection (incidence rate of HIV infection = 8.8 cases/1000 woman years, 95% confidence interval (CI): 5.4-14.4). Reported current use of injecting drugs at the first visit was associated with an increased risk of HIV infection (relative risk, RR = 12.87, 95% CI: 4.81-34.15) as well as having an usual partner with injecting drug addiction (RR = 20.89, 95% CI: 7.44-58.70). Infection also was associated with younger age (RR for 1 year = 0.86, 95% CI: 0.76-0.96). After multivariate adjustment using Poisson regression analysis, the factors that remained significantly associated with the risk of HIV infection were current use of injecting drugs (RR = 4.61, 95% CI: 1.37-15.46), and having a usual partner with injecting drug addiction (RR = 10.08, 95% CI: 2.94-34.57). There was also some evidence that a younger age could be related to infection. CONCLUSION: These data suggest that the risk of HIV infection among this cohort of female sex workers in Alicante is predominately associated with the use of injecting drugs, and having a regular partner with injecting drug addiction. An increasing number of clients did not play a role in the risk of infection.
Detection of Chlamydia trachomatis in genital swabs: comparison of commercial and in house amplification methods with culture.
Authors: Shattock R M , Patrizio C , Simmonds P , Sutherland S
Published: January 2009

AIMS: To evaluate the sensitivity of the Roche Cobas, Roche Amplicor plate kit, ligase chain reaction (LCR), and an in house polymerase chain reaction (PCR) by titration of purified elementary bodies (EB) and also to test 245 urethral and endocervical specimens for Chlamydia trachomatis by the four assays as well as conventional culture. STUDY DESIGN: EB titrations were run in duplicate in each commercial assay and six times in the in house PCR. Clinical samples were aliquoted and tested by each assay and were considered positive if C trachomatis was detected by two or more separate tests or if the sample was either culture or immunofluorescence positive. Major outer membrane protein (MOMP) specific primers were used as a confirmatory assay for the in house PCR. RESULTS: The in house PCR, Roche Cobas Amplicor, LCR, and Amplicor plate kit gave detection limits of approximately 1, 1-2, 2, and 2-4 EBs respectively. By the criteria described above for definition of a C trachomatis positive result in clinical samples we identified 23 true positives among the 245 clinical specimens. The in house PCR detected all 23 giving a sensitivity of 100% and a specificity of 98%. The Roche Cobas Amplicor, Roche Amplicor plate kit, and LCR detected 21, 19, and 19 of these respectively giving sensitivities of 87.5%, 82%, and 82% respectively and specificities of 99.5%, 99%, and 100% respectively. The culture gave a sensitivity of 78% and specificity of 100%. CONCLUSION: All four amplification assays had a greater sensitivity than the culture used routinely in this laboratory. The in house plasmid PCR had the greatest sensitivity and when combined with confirmation by immunofluorescence detected the greatest number of positives. This increased sensitivity is likely to have been achieved by the use of a DNA purification step and of nested primers in the amplification stage and their combined use in routine diagnostic assays for chlamydia might increase the frequency of C trachomatis detections. However, this assay is much less user friendly than the two semiautomated commercial assays investigated in this study.
Extragenital donovanosis of the foot.
Authors: Rao M V , Thappa D M , Jaisankar T J , Ratnakar C
Published: January 2009

An extremely rare case of primary extragenital donovanosis affecting the dorsa of right foot is reported. Clinical and histopathological features of the disease are described and the rarity, absence of genital lesions, and consequent difficulty in diagnosis are discussed.
VASP is involved in cAMP-mediated Rac 1 activation in microvascular endothelial cells
Authors: Schlegel Nicolas , Waschke Jens
Published: January 2009

Accumulating evidence points to a significant role of vasodilator-stimulated phosphoprotein (VASP) in the maintenance of endothelial barrier functions. We have recently shown that impaired barrier functions in VASP-deficient microvascular myocardial endothelial cells (MyEnd VASP−/−) correlated with decreased Rac 1 activity. To further test the hypothesis that VASP is involved in regulation of Rac 1 activity, we studied cAMP-dependent Rac 1 activation. Both inhibition of Rac 1 activation by NSC-23766 and inhibition of PKA by PKI completely blunted the efficacy of forskolin/rolipram (F/R)-mediated cAMP increase to stabilize barrier functions as revealed by measurements of transendothelial resistance (TER). Because these results indicate that PKA/Rac 1 activation is important for barrier stabilization, we tested this signaling pathway in VASP−/− cells. We found that F/R and isoproterenol reduced permeability measured as FITC-dextran flux across VASP−/− monolayers, but not below baseline levels of wild-type cells (WT). Moreover, cAMP-mediated Rac 1 activation was reduced to ∼50% of WT levels, and both PKA inhibition by PKI and PKA anchoring via A kinase anchoring peptides (AKAPs) by HT31 almost completely abolished Rac 1 activation in VASP−/− and WT endothelium. Accordingly, HT31 significantly reduced F/R-mediated TER increase in WT cells and completely blocked the protective effect of cAMP on endothelial barrier properties. Together, our data underline the significant role of cAMP-mediated Rac 1 activation for endothelial barrier stabilization and demonstrate that both AKAP-mediated PKA anchoring and VASP are required for this process.
Nox4 NADPH oxidase mediates oxidative stress and apoptosis caused by TNF-α in cerebral vascular endothelial cells
Authors: Basuroy Shyamali , Bhattacharya Sujoy , Leffler Charles W. , Parfenova Helena
Published: January 2009

Inflammatory brain disease may damage cerebral vascular endothelium leading to cerebral blood flow dysregulation. The proinflammatory cytokine TNF-α causes oxidative stress and apoptosis in cerebral microvascular endothelial cells (CMVEC) from newborn pigs. We investigated contribution of major cellular sources of reactive oxygen species to endothelial inflammatory response. Nitric oxide synthase and xanthine oxidase inhibitors ( Nω-nitro-l-arginine and allopurinol) had no effect, while mitochondrial electron transport inhibitors (CCCP, 2-thenoyltrifluoroacetone, and rotenone) attenuated TNF-α-induced superoxide (O2•−) and apoptosis. NADPH oxidase inhibitors (diphenylene iodonium and apocynin) greatly reduced TNF-α-evoked O2•− generation and apoptosis. TNF-α rapidly increased NADPH oxidase activity in CMVEC. Nox4, the cell-specific catalytic subunit of NADPH oxidase, is highly expressed in CMVEC, contributes to basal O2•− production, and accounts for a burst of oxidative stress in response to TNF-α. Nox4 small interfering RNA, but not Nox2, knockdown prevented oxidative stress and apoptosis caused by TNF-α in CMVEC. Nox4 is colocalized with HO-2, the constitutive isoform of heme oxygenase (HO), which is critical for endothelial protection against TNF-α toxicity. The products of HO activity, bilirubin and carbon monoxide (CO, as a CO-releasing molecule, CORM-A1), inhibited Nox4-generated O2•− and apoptosis caused by TNF-α stimulation. We conclude that Nox4 is the primary source of inflammation- and TNF-α-induced oxidative stress leading to apoptosis in brain endothelial cells. The ability of CO and bilirubin to combat TNF-α-induced oxidative stress by inhibiting Nox4 activity and/or by O2•− scavenging, taken together with close intracellular compartmentalization of HO-2 and Nox4 in cerebral vascular endothelium, may contribute to HO-2 cytoprotection against inflammatory cerebrovascular disease.
Short food deprivation inhibits orexin receptor 1 expression and orexin-A induced intracellular calcium signaling in acutely isolated duodenal enterocytes
Authors: Bengtsson Magnus W. , Mäkelä Kari , Herzig Karl-Heinz , Flemström Gunnar
Published: January 2009

Close intra-arterial infusion of the appetite regulating peptide orexin-A stimulates bicarbonate secretion from the duodenal mucosa. The aim of the present study was to elucidate the ability of orexin-A to induce intracellular calcium signaling in acutely isolated duodenal enterocytes. Freshly isolated clusters of enterocytes, obtained from rat duodenal mucosa or human duodenal biopsies, were loaded with fura 2-AM and mounted in a perfusion chamber. Cryptlike enterocytes were selected (caged), and changes in intracellular calcium concentration ([Ca2+]i) were evaluated by fluorescence imaging. Total RNA was extracted from pellets of enterocytes and reverse transcribed to cDNA, and expression of orexin receptors 1 and 2 (OX1R and OX2R) was measured by quantitative real-time PCR. Orexin-A at all concentrations tested (1–100 nM) increased [Ca2+]iin enterocytes isolated from continuously fed rats, and the OX1R-antagonist SB-334867 (10 nM) attenuated the response. The primary [Ca2+]iresponse was a slow increase to a sustained plateau persisting after orexin-A removal, and a similar response was observed in enterocytes from human biopsies. In contrast to orexin-A, the OX2R agonist (Ala11,d-Leu15)-orexin-B (1–10 nM) did not induce calcium signaling. There were no significant [Ca2+]iresponses in enterocytes from animals food deprived overnight, and overnight fasting decreased ( P < 0.01) enterocyte OX1R as well as OX2R mRNA. Induction of intracellular calcium signaling in isolated duodenal enterocytes is thus mediated primarily by OX1R receptors. Short (overnight) food deprivation markedly depresses receptor expression and inhibits orexin-A induced increases in [Ca2+]i. Studies of enterocyte signaling and intestinal secretion requires particular evaluation regarding feeding status.
Early but not late administration of glucagon-like peptide-2 following ileo-cecal resection augments putative intestinal stem cell expansion
Authors: Garrison Aaron P. , Dekaney Christopher M. , von Allmen Douglas C. , Lund P. Kay , Henning Susan J. , Helmrath Michael A.
Published: January 2009

Expansion of intestinal progenitors and putative stem cells (pISC) occurs early and transiently following ileo-cecal resection (ICR). The mechanism controlling this process is not defined. We hypothesized that glucagon-like peptide-2 (GLP-2) would augment jejunal pISC expansion only when administered to mice immediately after ICR. Since recent reports demonstrated increases in intestinal insulin-like growth factor (IGF)-I following GLP-2 administration, we further hypothesized that increased intestinal IGF-I expression would correlate with pISC expansion following ICR. To assess this, GLP-2 or vehicle was administered to mice either immediately after resection (early) or before tissue harvest 6 wk following ICR (late). Histological analysis quantified proliferation and intestinal morphometrics. Serum levels of GLP-2 were measured by ELISA and jejunal IGF-I mRNA by qRT-PCR. Expansion of jejunal pISC was assessed by fluorescent-activated cell sorting of side population cells, immunohistochemistry for phosphorylated β-catenin at serine 552 (a pISC marker), percent of crypt fission, and total numbers of crypts per jejunal circumference. We found that early but not late GLP-2 treatment after ICR significantly augmented pISC expansion. Increases in jejunal IGF-I mRNA correlated temporally with early pISC expansion and effects of GLP-2. Early GLP-2 increased crypt fission and accelerated adaptive increases in crypt number and intestinal caliber. GLP-2 increased proliferation and intestinal morphometrics in all groups. This study shows that, in mice, GLP-2 promotes jejunal pISC expansion only in the period immediately following ICR. This is associated with increased IGF-I and accelerated adaptive increases in mucosal mass. These data provide clinical rationale relevant to the optimal timing of GLP-2 in patients with intestinal failure.
Trauma-hemorrhagic shock-induced pulmonary epithelial and endothelial cell injury utilizes different programmed cell death signaling pathways
Authors: Barlos Dimtrios , Deitch Edwin A. , Watkins Anthony C. , Caputo Frank J. , Lu Qi , Abungu Billy , Colorado Iriana , Xu Da-Zhong , Feinman Rena
Published: January 2009

Intestinal ischemia after trauma-hemorrhagic shock (T/HS) results in gut barrier dysfunction and the production/release of biologically active and tissue injurious factors in the mesenteric lymph, which, in turn, causes acute lung injury and a systemic inflammatory state. Since T/HS-induced lung injury is associated with pulmonary endothelial and epithelial cell programmed cell death (PCD) and was abrogated by mesenteric lymph duct ligation, we sought to investigate the cellular pathways involved. Compared with trauma-sham shock (T/SS) rats, a significant increase in caspase-3 and M30 expression was detected in the pulmonary epithelial cells undergoing PCD, whereas apoptosis-inducing factor (AIF), but not caspase-3, was detected in endothelial cells undergoing PCD. This AIF-mediated pulmonary endothelial PCD response was validated in an in situ femoral vein assay where endothelial cells were found to express AIF but not caspase-3. To complement these studies, human umbilical vein endothelial cell (HUVEC), human lung microvascular endothelial cell (HLMEC), and human alveolar type II epithelial cell (A549) lines were used as in vitro models. T/HS lymph induced the nuclear translocation of AIF in HUVEC and HLMEC, and caspase inhibition in these cells did not afford any cytoprotection. For proof of principle, AIF silencing in HUVEC reversed the cytotoxic effects of T/HS on cell viability and DNA fragmentation. In A549 cells, T/HS lymph activated caspase-3-mediated apoptosis, which was partially abrogated by N-benzyloxycarbonyl-Val-Ala-Asp (zVAD). Additionally, T/HS lymph did not cause the nuclear translocation of AIF in A549 cells. Collectively, T/HS-induced pulmonary endothelial PCD occurs via an AIF-dependent caspase-independent pathway, whereas epithelial cells undergo apoptosis by a caspase-dependent pathway.
Modulation of PKCδ signaling alters the shear stress-mediated increases in endothelial nitric oxide synthase transcription: role of STAT3
Authors: Sud Neetu , Kumar Sanjiv , Wedgwood Stephen , Black Stephen M.
Published: January 2009

We have previously shown that the regulation of endothelial nitric oxide synthase (eNOS) in endothelial cells isolated from fetal lamb under static conditions is positively regulated by PKCδ. In this study, we explore the role of PKCδ in regulating shear-induced upregulation of eNOS. We found that shear caused a decrease in PKCδ activation. Modulation of PKCδ before shear with a dominant negative mutant of PKCδ (DN PKCδ) or bryostatin (a known PKCδ activator) demonstrated that PKCδ inhibition potentiates the shear-mediated increases in eNOS expression and activity, while PKCδ activation inhibited these events. To gain insight into the mechanism by which PKCδ inhibits shear-induced eNOS expression, we examined activation of STAT3, a known target for PKCδ phosphorylation. We found that shear decreased the phosphorylation of STAT3. Further the transfection of cells with DN PKCδ reduced, while PKCδ activation enhanced, STAT3 phosphorylation in the presence of shear. Transfection of cells with a dominant negative mutant of STAT3 enhanced eNOS promoter activity and nitric oxide production in response to shear. Finally, we found that mutating the STAT3 binding site sequence within the eNOS promoter increased promoter activity in response to shear and that this was no longer inhibited by bryostatin. In conclusion, shear decreases PKCδ activity and, subsequently, reduces STAT3 binding to the eNOS promoter. This signaling pathway plays a previously unidentified role in the regulation of eNOS expression by shear stress.
Airway inflammatory cell responses to intra-amniotic lipopolysaccharide in a sheep model of chorioamnionitis
Authors: Cheah Fook-Choe , Pillow J. Jane , Kramer Boris W. , Polglase Graeme R. , Nitsos Ilias , Newnham John P. , Jobe Alan H. , Kallapur Suhas G.
Published: January 2009

Chorioamnionitis, a risk factor for bronchopulmonary dysplasia in preterm infants, causes an influx of inflammatory cells into the fetal lung. Using a fetal sheep model, we evaluated the time course of activation, functional maturity, and apoptosis of the leukocytes recruited to the fetal air spaces by lipopolysaccharide (LPS). Time-mated sheep were given intra-amniotic injections with 10 mg of Escherichia coli LPS or saline 2 or 7 days before preterm delivery at 124 days of gestation (term is 150 days). Both neutrophils and monocytes in bronchoalveolar lavage fluid (BALF) had activated NF-κB after 2- and 7-day LPS exposures. These neutrophils and monocytes expressed the activation factor CD11b and the maturation factor PU.1 at 2 days, and increased PU.1 expression was detected in macrophages at 7 days. Leukocyte oxidative burst activity was greatest at 7 days. BALF lipid peroxidation increased fivefold at 2 days, while protein carbonyls increased eightfold at 7 days. Nitrative stress was not detected in the BALF, but leukocytes in the lung expressed nitric oxide synthase (NOS)II (inducible NOS). BALF leukocytes expressed the antioxidant peroxiredoxin V. Lung glutathione peroxidase was also increased with LPS exposure. There was minimal apoptosis of airway and lung leukocytes assessed by caspase-3 activation. Intra-amniotic LPS recruits leukocytes to the fetal air space that have a persistent activation. These results have implications for the pathogenesis of lung inflammatory disorders in the preterm.
Optic nerve sheath diameter correlates with the presence and severity of acute mountain sickness: evidence for increased intracranial pressure
Authors: Fagenholz Peter J. , Gutman Jonathan A. , Murray Alice F. , Noble Vicki E. , Camargo Carlos A. , Harris N. Stuart
Published: January 2009

Increased intracranial pressure is suspected in the pathogenesis of acute mountain sickness (AMS), but no studies have correlated it with the presence or severity of AMS. We sought to determine whether increased optic nerve sheath diameter, a surrogate measure of intracranial pressure, is associated with the presence and severity of AMS. We performed a cross-sectional study of travelers ascending through Pheriche, Nepal (4,240 m), from March 3 to May 14, 2006. AMS was assessed using the Lake Louise score. Optic nerve sheath diameter was measured by ultrasound. Ultrasound exams were performed and read by separate blinded observers. Two-hundred eighty seven subjects were enrolled. Ten of these underwent repeat examination. Mean optic nerve sheath diameter was 5.34 mm [95% confidence interval (CI) 5.18–5.51 mm] in the 69 subjects with AMS vs. 4.46 mm (95% CI 4.39–4.54 mm) in the 218 other subjects ( P < 0.0001). There was also a positive association between optic nerve sheath diameter and total Lake Louise score ( P for trend < 0.0001). In a multivariate logistic regression model of factors associated with AMS, optic nerve sheath diameter was strongly associated with AMS (odds ratio 6.3; 95% CI, 3.7–10.8; P < 0.001). In 10 subjects with repeat examinations, change in Lake Louise score had a strong positive correlation with change in optic nerve sheath diameter ( R2 = 0.84, P < 0.001). Optic nerve sheath diameter, a proxy for intracranial pressure, is associated with the presence and severity of AMS.
Influence of cerebral blood flow on breathing stability
Authors: Xie Ailiang , Skatrud James B. , Barczi Steven R. , Reichmuth Kevin , Morgan Barbara J. , Mont Sara , Dempsey Jerome A.
Published: January 2009

Our previous work showed a diminished cerebral blood flow (CBF) response to changes in PaCO2 in congestive heart failure patients with central sleep apnea compared with those without apnea. Since the regulation of CBF serves to minimize oscillations in H+ and Pco2 at the site of the central chemoreceptors, it may play an important role in maintaining breathing stability. We hypothesized that an attenuated cerebrovascular reactivity to changes in PaCO2 would narrow the difference between the eupneic PaCO2 and the apneic threshold PaCO2 (ΔPaCO2), known as the CO2 reserve, thereby making the subjects more susceptible to apnea. Accordingly, in seven normal subjects, we used indomethacin (Indo; 100 mg by mouth) sufficient to reduce the CBF response to CO2 by ∼25% below control. The CO2 reserve was estimated during non-rapid eye movement (NREM) sleep. The apnea threshold was determined, both with and without Indo, in NREM sleep, in a random order using a ventilator in pressure support mode to gradually reduce PaCO2 until apnea occurred. results: Indo significantly reduced the CO2 reserve required to produce apnea from 6.3 ± 0.5 to 4.4 ± 0.7 mmHg ( P = 0.01) and increased the slope of the ventilation decrease in response to hypocapnic inhibition below eupnea (control vs. Indo: 1.06 ± 0.10 vs. 1.61 ± 0.27 l·min−1·mmHg−1, P < 0.05). We conclude that reductions in the normal cerebral vascular response to hypocapnia will increase the susceptibility to apneas and breathing instability during sleep.
Postnatal development of metabolic rate during normoxia and acute hypoxia in rats: implication for a sensitive period
Authors: Liu Qiuli , Fehring Charles , Lowry Timothy F. , Wong-Riley Margaret T. T.
Published: January 2009

Previously, we reported that the hypoxic ventilatory response (HVR) in rats was weakest at postnatal day (P) P13, concomitant with neurochemical changes in respiratory nuclei. A major determinant of minute ventilation (V̇e) is reportedly the metabolic rate [O2consumption (V̇o2) and CO2production (V̇co2)]. The present study aimed at testing our hypothesis that daily metabolic rates changed in parallel with ventilation during development and that a weak HVR at P13 was attributable mainly to an inadequate metabolic rate in hypoxia. Ventilation and metabolic rates were monitored daily in P0–P21 rats. We found that 1) ventilation and metabolic rates were not always correlated, and V̇e/V̇o2and V̇e/V̇co2ratios were not constant during development; 2) metabolic rate and V̇e/V̇o2and V̇e/V̇co2ratios at P0–P1 were significantly different from the remaining first postnatal week in normoxia and hypoxia; 3) at P13, metabolic rates and V̇e/V̇o2and V̇e/V̇co2ratios abruptly increased in normoxia and were compromised in acute hypoxia, unlike more stable trends during the remaining second and third postnatal weeks; and 4) the respiratory quotient (V̇co2/V̇o2) was quite stable in normoxia and fluctuated slightly in hypoxia from P0 to P21. Thus our data revealed heretofore unsuspected metabolic adjustments at P0–P1 and P13. At P0–P1, ventilation and metabolic rates were uncorrelated, whereas at P13, they were closely correlated under normoxia and hypoxia. The findings further strengthened the existence of a critical period of respiratory development around P13, when multiple physiological and neurochemical adjustments occur simultaneously.
Signals of motor command bias joint position sense in the presence of feedback from proprioceptors
Authors: Smith Janette L. , Crawford Matthew , Proske Uwe , Taylor Janet L. , Gandevia Simon C.
Published: January 2009

Joint position sense is believed to be mediated by muscle afferent signals. Because a “phantom” hand produced by a sensory and motor nerve block appears to move in the direction of voluntary effort, signals of “motor command” or “effort” can influence perceived joint position. To determine whether this occurs when sensory signals are available, three studies assessed position sense when motor command and afferent signals were available, but joint movement was prevented. First, the hand was positioned to stop movement at the proximal joint of the middle finger, and movement at the distal joint was impossible because the muscles had been “disengaged”. Voluntary efforts produced illusory position changes in the direction of the effort (12.6 ± 2.0° distal joint; 12.3 ± 2.3° proximal joint for efforts at 30% maximum; means ± SD). Second, when subjects attempted to move the index finger under isometric conditions, the index finger appeared to move 7.4 ± 1.2° in the direction of efforts. These illusions graded with the level of effort (10 or 30% maximum) and far exceeded any real joint movement. Finally, because changes in muscle afferent feedback might have accompanied the voluntary efforts, all forearm and hand muscles were completely paralyzed by locally infused rocuronium. During paralysis, passive wrist position was signaled accurately, but, during attempted efforts (30% maximum), perceived wrist position changed by 9.7 ± 4.9°. Before paralysis, isometric efforts changed it by 6.7 ± 3.6°. Thus all studies concur: when joint movement is prevented, signals of motor command contribute to joint position sense.
Modularity of Endpoint Force Patterns Evoked Using Intraspinal Microstimulation in Treadmill Trained and/or Neurotrophin-Treated Chronic Spinal Cats
Authors: Boyce Vanessa S. , Lemay Michel A.
Published: January 2009

Chronic spinal cats with neurotrophin-secreting fibroblasts (NTF) transplants recover locomotor function. To ascertain possible mechanisms, intraspinal microstimulation was used to examine the lumbar spinal cord motor output of four groups of chronic spinal cats: untrained cats with unmodified-fibroblasts graft (Op-control) or NTF graft and locomotor-trained cats with unmodified-fibroblasts graft (Trained) or NTF graft (Combination). Forces generated via intraspinal microstimulation at different hindlimb positions were recorded and interpolated, generating representations of force patterns at the paw. Electromyographs (EMGs) of hindlimb muscles, medial gastrocnemius, tibialis anterior, vastus lateralis, and biceps femoris posterior, were also collected to examine relationships between activated muscles and force pattern types. The same four force pattern types obtained in spinal-intact cats were found in chronic spinal cats. Proportions of force patterns in spinal cats differed significantly from those in intact cats, but no significant differences in proportions were observed among individual spinal groups (Op-control, NTF, Trained, and Combination). However, the proportions of force patterns differed significantly between trained (Trained and Combination) and untrained groups (Op-control and NTF). Thus the frequency of expression of some response types was modified by injury and to a lesser extent by training. Force pattern laminar distribution differed in spinal cats compared with intact, with more responses obtained dorsally (0–1,000 μm) and fewer ventrally (3,200–5,200 μm). EMG analysis demonstrated that muscle activity highly predicted some force pattern types and was independent of hindlimb position. We conclude that spinal motor output modularity is preserved after injury.
Quantitative Assessment of the Distributions of Membrane Conductances Involved in Action Potential Backpropagation Along Basal Dendrites
Authors: Acker Corey D. , Antic Srdjan D.
Published: January 2009

Basal dendrites of prefrontal cortical neurons receive strong synaptic drive from recurrent excitatory synaptic inputs. Synaptic integration within basal dendrites is therefore likely to play an important role in cortical information processing. Both synaptic integration and synaptic plasticity depend crucially on dendritic membrane excitability and the backpropagation of action potentials. We carried out multisite voltage-sensitive dye imaging of membrane potential transients from thin basal branches of prefrontal cortical pyramidal neurons before and after application of channel blockers. We found that backpropagating action potentials (bAPs) are predominantly controlled by voltage-gated sodium and A-type potassium channels. In contrast, pharmacologically blocking the delayed rectifier potassium, voltage-gated calcium, or Ih conductance had little effect on dendritic AP propagation. Optically recorded bAP waveforms were quantified and multicompartmental modeling was used to link the observed behavior with the underlying biophysical properties. The best-fit model included a nonuniform sodium channel distribution with decreasing conductance with distance from the soma, together with a nonuniform (increasing) A-type potassium conductance. AP amplitudes decline with distance in this model, but to a lesser extent than previously thought. We used this model to explore the mechanisms underlying two sets of published data involving high-frequency trains of APs and the local generation of sodium spikelets. We also explored the conditions under which IA down-regulation would produce branch strength potentiation in the proposed model. Finally, we discuss the hypothesis that a fraction of basal branches may have different membrane properties compared with sister branches in the same dendritic tree.
Fusion of Visual and Vestibular Tilt Cues in the Perception of Visual Vertical
Authors: Vingerhoets R. A. A. , De Vrijer M. , Van Gisbergen J. A. M. , Medendorp W. P.
Published: January 2009

We investigated the effect of visual and vestibular body-tilt cues on the subjective visual vertical (SVV) in six human observers at roll tilts of 0, 60, and 120°. Subjects adjusted a small luminous test line parallel to the perceived direction of gravity, in the presence of a large peripheral visual frame line. These settings, referred to as the frame SVV, were compared with the SVV in complete darkness (dark SVV). The frame SVV was virtually identical to the dark SVV for frame lines parallel or orthogonal to the dark SVV. Away from these neutral positions, the frame induced a periodic SVV modulation, which was small in upright observers, but became quite pronounced when subjects were tilted. For upright, where the dark SVV was very accurate, the frame SVV showed errors in both directions, following a roughly symmetrical pattern. At 120° tilt, where the dark SVV invariably showed tilt undercompensation (A-effect), the frame effect became asymmetrical, with a stronger tendency to improve than to worsen accuracy. We tested whether our findings could be explained by two spatial orientation models: Mittelstaedt's idiotropic model and a Bayesian scheme with a stage for the processing of visual cues. Both models show a periodic frame effect that becomes stronger with increasing body tilt and can explain why frame lines parallel or perpendicular to the dark SVV are ineffective. Based on their performance, we conclude that perception of the visual vertical is based on a centrally weighted fusion of visual, vestibular, and egocentric references.
The Na+/Ca2+Exchanger Inhibitor, KB-R7943, Blocks a Nonselective Cation Channel Implicated in Chemosensory Transduction
Authors: Pezier A. , Bobkov Y. V. , Ache B. W.
Published: January 2009

The mechanism(s) of olfactory transduction in invertebrates remains to be fully understood. In lobster olfactory receptor neurons (ORNs), a nonselective sodium-gated cation (SGC) channel, a presumptive transient receptor potential (TRP)C channel homolog, plays a crucial role in olfactory transduction, at least in part by amplifying the primary transduction current. To better determine the functional role of the channel, it is important to selectively block the channel independently of other elements of the transduction cascade, causing us to search for specific pharmacological blockers of the SGC channel. Given evidence that the Na+/Ca2+exchange inhibitor, KB-R7943, blocks mammalian TRPC channels, we studied this probe as a potential blocker of the lobster SGC channel. KB-R7943 reversibly blocked the SGC current in both inside- and outside-out patch recordings in a dose- and voltage-dependent manner. KB-R7943 decreased the channel open probability without changing single channel amplitude. KB-R7943 also reversibly and in a dose-dependent manner inhibited both the odorant-evoked discharge of lobster ORNs and the odorant-evoked whole cell current. Our findings strongly imply that KB-R7943 potently blocks the lobster SGC channel and likely does so directly and not through its ability to block the Na+/Ca2+exchanger.
The Pontomedullary Reticular Formation Contributes to the Compensatory Postural Responses Observed Following Removal of the Support Surface in the Standing Cat
Authors: Stapley Paul J. , Drew Trevor
Published: January 2009

This study was designed to determine the contribution of reticular neurons in the pontomedullary reticular formation (PMRF) to the postural responses produced to compensate for an unexpected perturbation. We recorded the activity of 48 neurons in the PMRF, including 41 reticulospinal neurons, to removal of the support surface under each of the four limbs in four cats. The perturbations produced robust postural responses that were divided into three periods: an initial postural response (P1) that displaced the center of vertical pressure over the two diagonal supporting limbs; a secondary response (P2) during which the cat restored a tripedal support pattern; and a prolonged tertiary response (P3) that maintained a stable posture over all three supporting limbs. Most (44/48) reticular neurons showed modified activity to perturbation of at least one limb and a majority (39/48) showed changes in activity to perturbations of more than one limb. A few (7/48) discharged to perturbations of all four limbs. Discharge frequency in neurons showing increased activity during P1 was relatively high (>100 Hz in 57% of the neurons responding to perturbations of either the left or right forelimbs, lFl and rFL) and of short latency (17 ms for the lFL and 14 ms for the rFL). Discharge activity in most neurons was sustained throughout P2 and P3 but at a reduced level. These data show that neurons in the PMRF discharge strongly in response to unexpected perturbations and in a manner consistent with a contribution to the compensatory responses that restore equilibrium.
Effect of Iron Therapy on Platelet Function among Iron-Deficient Women with Unexplained Menorrhagia
Authors: Akay Olga Meltem , Akın Enver , Mutlu Fezan Sahin , Gulbas Zafer
Published: January 2009

This study was performed to evaluate the effect of iron therapy on platelet function among women with unexplained menorrhagia in order to better understand possible interactions between iron deficiency anemia and platelet behavior and menorrhagia. Platelet aggregation and adenosine triphosphate (ATP) release induced by 5.0 mM adenosine diphosphate (ADP), 0.5 mM arachidonic acid (AA), 1.0 mg/ml ristocetin and 2 μg/ml collagen were studied by whole-blood platelet lumi-aggregometer in 50 menorrhagic women before and after oral iron therapy and in 22 women of the control group. There was a significant increase in AA- induced platelet aggregation (p < 0.05) and a decrease in ristocetin-induced platelet aggregation (p < 0.01) after treatment. Pre- and posttreatment platelet aggregation responses to ADP and collagen were not significantly different (p > 0.05). Pre- and posttreatment platelet secretion responses to all agonists disclosed no significant difference (p > 0.05). There was no significant difference between the study group after treatment and the control group in respect to platelet aggregation and ATP secretion values induced by all agonists (p > 0.05). We conclude that iron deficiency anemia in women causes AA-induced platelet dysfunction, which may give rise to increased menstrual blood loss and can be reversed by iron repletion.
The Ross Procedure
Authors: Takkenberg Johanna J.M. , Klieverik Loes M.A. , Schoof Paul H. , van Suylen Robert-Jan , van Herwerden Lex A. , Zondervan Pieter E. , Roos-Hesselink Jolien W. , Eijkemans Marinus J.C. , Yacoub Magdi H. , Bogers Ad J.J.C.
Published: January 2009

Background—

Reports on outcome after the Ross procedure are limited by small study size and show variable durability results. A systematic review of evidence on outcome after the Ross procedure may improve insight into outcome and potential determinants.

Methods and Results—

A systematic review of reports published from January 2000 to January 2008 on outcome after the Ross procedure was undertaken. Thirty-nine articles meeting the inclusion criteria were allocated to 3 categories: (1) consecutive series, (2) adult patient series, and (3) pediatric patient series. With the use of an inverse variance approach, pooled morbidity and mortality rates were obtained. Pooled early mortality for consecutive, adult, and pediatric patients series was 3.0% (95% confidence interval [CI], 1.8 to 4.9), 3.2% (95% CI, 1.5 to 6.6), and 4.2% (95% CI, 1.4 to 11.5). Autograft deterioration rates were 1.15% (95% CI, 1.06 to 2.06), 0.78% (95% CI, 0.43 to 1.40), and 1.38%/patient-year (95% CI, 0.68 to 2.80), respectively, and for right ventricular outflow tract conduit were 0.91% (95% CI, 0.56 to 1.47), 0.55% (95% CI, 0.26 to 1.17), and 1.60%/patient-year (95% CI, 0.84 to 3.05), respectively. For studies with mean patient age >18 years versus mean patient age ≤18 years, pooled autograft and right ventricular outflow tract deterioration rates were 1.14% (95% CI, 0.83 to 1.57) versus 1.69% (95% CI, 1.02 to 2.79) and 0.65% (95% CI, 0.41 to 1.02) versus 1.66%/patient-year (95% CI, 0.98 to 2.82), respectively.

Conclusions—

The Ross procedure provides satisfactory results for both children and young adults. Durability limitations become apparent by the end of the first postoperative decade, in particular in younger patients.
Hypoxia Induces Near-Native Mechanical Properties in Engineered Heart Valve Tissue
Authors: Balguid Angelique , Mol Anita , van Vlimmeren Marijke A.A. , Baaijens Frank P.T. , Bouten Carlijn V.C.
Published: January 2009

Background—

Previous attempts in heart valve tissue engineering (TE) failed to produce autologous valve replacements with native-like mechanical behavior to allow for systemic pressure applications. Because hypoxia and insulin are known to promote protein synthesis by adaptive cellular responses, a physiologically relevant oxygen tension and insulin supplements were applied to the growing heart valve tissues to enhance their mechanical properties.

Methods and Results—

Scaffolds of rapid-degrading polyglycolic acid meshes coated with poly-4-hydroxybutyrate were seeded with human saphenous vein myofibroblasts. The tissue-engineered constructs were cultured under normal oxygen tension (normoxia) or hypoxia (7% O
2
) and incubated with or without insulin. Glycosaminoglycan production in the constructs approached that of native values under the influence of hypoxia and under the influence of insulin. Both insulin and hypoxia were associated with enhanced matrix production and improved mechanical properties; however, a synergistic effect was not observed. Although the amount of collagen and cross-links in the engineered tissues was still lower than that in native adult human aortic valves, constructs cultured under hypoxic conditions reached native human aortic valve levels of tissue strength and stiffness after 4 weeks of culturing.

Conclusions—

These results indicate that oxygen tension may be a key parameter for the achievement of sufficient tissue quality and mechanical integrity in tissue-engineered heart valves. Engineered tissues of such strength, based on rapid-degrading polymers, have not been achieved to date. These findings bring the potential use of tissue-engineered heart valves for systemic applications a step closer and represent an important improvement in heart valve tissue engineering.