Dose-dependent Negative Effect Research Articles

Effects of metformin on fertilisation of bovine oocytes and early embryo development: possible involvement of AMPK3-mediated TSC2 activation

Studies on bovine oocytes have revealed that the activation of adenosine monophosphate activated protein kinase (AMPK) by millimolar concentrations of metformin controls nuclear maturation. Tuberous sclerosis complex 2 (TSC2) has been identified as a downstream target of AMPK. The objective of this study was to investigate the effects of addition of low concentrations of metformin (1 nM to 10 μM) on the percentage of cultured cumulus-oocyte complexes (COC) giving rise to cleavage-stage embryos and AMPK-mediated TSC2 activation. Metformin was supplemented either throughout in vitro embryo production (IVP) or only during in vitro fertilization (IVF). COC were matured in vitro, inseminated, and presumptive zygotes cultured for a further 72 h post insemination before the percentage of COC that gave rise to zygotes and early embryo development was assessed. The presence of TSC2 in bovine embryos and its possible AMPK-induced activation were assessed by immunocytochemistry. Metformin had a dose-dependent effect on the numbers of cultured COC that gave rise to embryos. Drug treatment either throughout IVP or only during IVF decreased the percentage of ≥ 8-cell embryos (1 μM, P < 0.05; 10 μM, P < 0.01; and 0.1 μM, 10 μM, P < 0.01, respectively) and increased the percentage of 2-cell embryos (10 μM, P < 0.01 and P < 0.05 respectively). The percentage of cultured COC that gave rise to zygotes was not affected by metformin. TSC2 is expressed in early embryos. Metformin (10 μM) either throughout IVP or during IVF only, increased AMPK-induced PhosphoS1387-TSC2 immunoreactivity (P < 0.01) and this increase corresponded to the total TSC2 protein levels expressed in cells. Our results suggest that there is a dose-dependent negative effect of metformin on the ability of oocytes to cleave following insemination, possibly mediated through an AMPK-induced activation of TSC2.

Effect of gamma radiation on growth and lignin content in Brachypodium distachyon

Brachypodium distachyon has been highlighted as a model monocot plant with small genome and short life cycle. Biofuels are being developed as renewable energy sources to replace fossil fuels. Bioethanol production is negatively correlated with lignin content. Here, Brachypodium was acutely or chronically irradiated at doses of 50, 100, 150, 200, and 250 Gy. The effect of radiation on plant growth and generation of mutant populations was explored. The lethal effect of radiation was higher in acutely irradiated M0 populations. A dose-dependent negative effect in plant height, tiller number, floral spikelet, and total seed number was observed, with a positive effect in days to heading. The phenotype of 1,773 M1 plants was evaluated, with 417 plants being selected to construct the M2 population. The 31 M2 plants that showed the least staining with phloroglucinol were selected. These mutants could be useful materials for studies such as identification of nucleotide substitutions in genes involved in lignin biosynthesis pathway, monitoring of mutant physiological traits, and evaluation of fitness for bioethanol production. As biological resources, the M2 populations generated in this work will contribute to studies of functional genomics of Brachypodium and to the breeding of grass crops.

Does Preincubation with Prostaglandin E1 or Prostaglandin E2 Enhance Oxytocin-Induced Myometrial Contractility In Vitro?

To determine if preincubation with prostaglandin E1 (PGE1) and E2 (PGE2) enhances oxytocin-induced myometrial contractility in vitro. Myometrial strips from 13 women were incubated with PGE1 (10-5 mol/L or 10-6 mol/L), PGE2 (10-5 mol/L or 10-6 mol/L) or solvent before adding cumulative concentrations of oxytocin (10-10 to 10-6 mol/L). The area under the contraction curve was calculated after addition of each agent. One- and two-way analysis of variance was used for comparison (significance p < 0.05). PGE2 10-5 mol/L reduced response to oxytocin 10-9 to 10-6 mol/L (p < 0.05). PGE2 reduced spontaneous myometrial contractility as compared with PGE1 (p < 0.05). A dose-dependent negative effect of prostaglandins was detected on oxytocin 10-8 mol/L (10-5 mol/L > 10-6 mol/L; p < 0.05). Contrary to the hypothesis, neither PGE1 nor PGE2 enhanced oxytocin-induced myometrial contractility; in fact, PGE2 decreased contractility.

The Effect of Celery (Apium graveolens) Extract on the Reproductive Hormones in Male Mice

Celery (Apium graveolens) has many therapeutic effects. This plant has many phytoestrogens that can affect on the reproductive endocrine system and can reduce fertility .In this study, Hydro alcoholic extracts of celery leaves on the pituitary -gonad axis in young male l mice of Balb/C was investigated. The samples were randomly divided into 5 groups (three treatment groups, placebo and control). Celery leaves hydroalcoholic extract in different doses (50, 100,150mg/kg/2day) was injected (IP) for 20 days. The Placebo group was used for injection of normal saline. The samples were randomly divided into 5 groups (three treatment groups, placebo and control). Celery leaves hydroalcoholic extract in different doses (50, 100,150mg/kg/2day) was injected (IP) for 20 days. The Placebo group was used for injection of normal saline. After 10 injections, samples bloods were analyzed for FSH, LH, and testosterone using RIA method and compared with control groups and compared with control groups. Concentrations of FSH in 100 and 150mg/kg decreased significantly while LH and testosterone concentrations in all experimental groups decreased (P<0.05). This study showed dose-dependent negative effect of celery extracts in the pituitary - gonad axis in male mice.

Characterization of a novel type of HIV-1 particle assembly inhibitor using a quantitative luciferase-Vpr packaging-based assay.

The HIV-1 auxiliary protein Vpr and Vpr-fusion proteins can be copackaged with Gag precursor (Pr55Gag) into virions or membrane-enveloped virus-like particles (VLP). Taking advantage of this property, we developed a simple and sensitive method to evaluate potential inhibitors of HIV-1 assembly in a living cell system. Two proteins were coexpressed in recombinant baculovirus-infected Sf9 cells, Pr55Gag, which formed the VLP backbone, and luciferase fused to the N-terminus of Vpr (LucVpr). VLP-encapsidated LucVpr retained the enzymatic activity of free luciferase. The levels of luciferase activity present in the pelletable fraction recovered from the culture medium correlated with the amounts of extracellular VLP released by Sf9 cells assayed by conventional immunological methods. Our luciferase-based assay was then applied to the characterization of betulinic acid (BA) derivatives that differed from the leader compound PA-457 (or DSB) by their substituant on carbon-28. The beta-alanine-conjugated and lysine-conjugated DSB could not be evaluated for their antiviral potentials due to their high cytotoxicity, whereas two other compounds with a lesser cytotoxicity, glycine-conjugated and ε-NH-Boc-lysine-conjugated DSB, exerted a dose-dependent negative effect on VLP assembly and budding. A fifth compound with a low cytotoxicity, EP-39 (ethylene diamine-conjugated DSB), showed a novel type of antiviral effect. EP-39 provoked an aberrant assembly of VLP, resulting in nonenveloped, morula-like particles of 100-nm in diameter. Each morula was composed of nanoparticle subunits of 20-nm in diameter, which possibly mimicked transient intermediates of the HIV-1 Gag assembly process. Chemical cross-linking in situ suggested that EP-39 favored the formation or/and persistence of Pr55Gag trimers over other oligomeric species. EP-39 showed a novel type of negative effect on HIV-1 assembly, targeting the Pr55Gag oligomerisation. The biological effect of EP-39 underlined the critical role of the nature of the side chain at position 28 of BA derivatives in their anti-HIV-1 activity.

Metformin Treatment Has No Beneficial Effect in a Dose-Response Survival Study in the SOD1G93A Mouse Model of ALS and Is Harmful in Female Mice

BackgroundAmyotrophic Lateral Sclerosis (ALS) is a devastating neurological disorder characterized by selective degeneration of upper and lower motor neurons. The primary triggers for motor neuron degeneration are unknown but inflammation, oxidative stress and mitochondrial defects have been identified as potential contributing factors. Metformin is an anti-type II diabetes drug that has anti-inflammatory and anti-oxidant properties, can bring about mitochondrial biogenesis and has been shown to attenuate pathology in mouse models of Huntington's disease and multiple sclerosis. We therefore hypothesized that it might increase survival in the SOD1G93A murine model of ALS.Methodology/Principal FindingsTreatment of male and female SOD1G93A mice (n = ≥6 per sex) with 2 mg/ml metformin in the drinking water from 35 days, resulted in a significant increase in motor unit survival, as measured by in vivo electrophysiology at 100 days, in male EDL muscles (24+/−2 vs. 14+/−2 motor units, p<0.005) and female TA muscles (21+/−1 vs. 15+/−2 motor units, P = 0.0134). We therefore continued to test the effect of 0.5, 2 and 5 mg/ml metformin in the drinking water from 35 days on disease onset and progression (identified by twice weekly determination of weight and neurological score) as well as survival in male and female SOD1G93A mice (n = ≥14 per sex). Results for all groups were compared using Kaplan-Meier time to event analyses. In this survival study, metformin was unable to reduce pathology at any dose and had an unexpected dose-dependent negative effect on the onset of neurological symptoms (P = 0.0236) and on disease progression (P = 0.0362) in female mice.Conclusions/SignificanceThis study suggests that metformin is a poor candidate for clinical trial in ALS patients and that the possibility of harmful effects of metformin in female ALS patients with type II diabetes should be investigated.

Negative inotropic effect induced by diethylamiloride (DEA) in rabbit myocardium

The effects of the Na+/H+ exchange blocking drug diethylamiloride (DEA) on mechanical function have been studied in the rabbit isolated, arterially perfused interventricular septum. At concentrations of 10(-6)-10(-5) M, DEA induced a significant, dose-dependent, negative inotropic effect (a 54% decrease from control values at the highest concentration), which was slow to develop. After a 45 min washout, recovery was almost complete (95 +/- 3.4%). At concentrations greater than 5 x 10(-5) M, DEA induced a rapid and marked decrease in developed tension, associated with a progressive decrease in excitability and incomplete recovery. Resting tension was not significantly modified at any of the concentrations tested. At greater than 10(-6) M DEA enhanced significantly the transient negative inotropic effect of the brief intracellular acidosis induced by removal of NH4Cl perfusion, both by decreasing the minimal value of developed tension and by increasing the time required to produce this effect. These effects suggest that the dose-dependent DEA negative inotropic effect could be mediated by a progressive intracellular acidosis produced by inhibition of the Na+/H+ exchange system.

Methylphenidate has dose-dependent negative effects on rat spermatogenesis: decreased round spermatids and testicular weight and increased p53 expression and apoptosis

In the present study, we aimed to evaluate the possible effects of methylphenidate on rat testes. Forty-two Wistar rats were randomly distributed into three experimental groups of 14 rats each. For 90 days, each group via gavage received the following: group 1 = tap water (control group), group 2 = 5 mg/kg/day of ritalin (methylphenidate, MPH), and group 3 = 10 mg/kg/day of ritalin. After sacrificing the animals, the body weights as well as the absolute and relative testicular weights were measured. Testes were sampled, fixed, and processed and, by histopathological examination, quantitative morphometric analysis of Sertoli cells, spermatocytes, and spermatids was performed in stages II, V, and XII. Immunohistochemistry was performed for transforming growth factor (TGF)-β1 and p53, and the apoptotic index was assessed through the TUNEL method. Group 2 had a reduction of round spermatids in stage II. Group 3 had reduction in both stage II and stage V spermatids, as well as lower testicular weight. The p53 expression was increased in group 3. In groups 2 and 3, the TGF-β1 expression was reduced and the apoptotic index by TUNEL was increased. Body weights remained stable on either group. Our results showed that methylphenidate might negatively affect spermatogenesis not only by reducing testicular weight and amount of round spermatids but also by increasing apoptotic death and p53 activation. The findings of the study, however, must be cautiously interpreted.

A Novel Mutation K673R In STAT1 Impaired the STAT1 Signal Transduction In a dominant– Negative Manner Identified In a Japanese Boy with MSMD

Abstract Abstract 1734 Mendelian susceptibility to mycobacterial disease (MSMD) is a rare congenital disorder characterized by susceptibility to infection by poorly virulent intracellular pathogens such as BCG, non-tuberculosis mycobacterium and Salmonellae. MSMD is associated with genetic defects in the IL-12/IFN-γ pathway, and six responsible genes, IFNGR1, IFNGR2, IL12B, IL12RB1, STAT1, and NEMO have been identified so far. Singnal transducer and activation of transcription 1 (STAT1) is a DNA-binding factor which regulates specific gene transcription. IFN-γ stimulation results in phosphorylation of STAT1 at Tyr701 (Y701) to induce the homodimerization, so called a gamma-activated factor (GAF), through the conformational change and the nuclear import. The GAF binds to the gamma-activated sequence (GAS) to induce the transcriptional activities. Patients with STAT1 deficiency were known in both recessive and dominant forms and three mutations in STAT1, L706S, E320Q and Q463H, have previously been reported from three family with an autosomal-dominant form of STAT1 partial deficiency. L706S mutation in the tail segment domain of STAT1 is shown to impair the phosphorylation at Tyr701. Although the phosphorylation is normal in other two mutations, the E320Q or Q463H mutant, in which the DNA-binding ability was abolished. Here we identified a novel heterozygous STAT1 mutation, 2018A&gt;G (K673R), in a Japanese patient with MSMD. This was thought to be first report whose mutation was identified in the SH2 domain of autosomal-dominant form of STAT1. He had a past history of BCGitis after vacctination and multifocal osteomyelitis at the age of 5. Bone biopsy revealed granulomatous change without detecting Mycobacterium. The same mutation was also identified in his father and older sister. Although his sister had a history of BCGitis, his father had no clinical manifestations. A peripheral blood mononuclear cells from the patient could not sufficiently produce TNF-α in response to IFN-γ. EB-transformed B cells from the patient showed that induction of STAT1 phosphorylation by IFN-γ was partially impaired. We generated Flag-tagged STAT1 expression constructs of wild-type (WT) and three mutants including our mutant and analyzed molecular functions along with STAT1 signaling. K673R STAT1 showed partial impairment in the phosphorylation in response to both IFN-α and IFN-γ. Further, the electrophoretic mobility shift assay revealed that the K673R mutant abolished the DNA-binding ability. The nuclear translocation was normally detected. Curiously, dose-dependent negative effect on WT STAT1 was observed in K673R mutant by the reporter assay. K673R mutant interacted with WT to abrogate the DNA-binding activity, thus, exerted a dominant-negative effect on the transcription activity of WT STAT1. Based on these results, a novel heterozygous mutation, K673R, in SH2 domain of the STAT1 gene impaired the STAT1 signal transduction in a dominant-negative manner. K673R mutation in STAT1 may play an important role in molecular pathogenesis of MSMD. Disclosures: No relevant conflicts of interest to declare.

Exposing cultured mouse ovarian follicles under increased gonadotropin tonus to aromatizable androgens influences the steroid balance and reduces oocyte meiotic capacity

Acquisition of oocyte developmental competence relies on the well-controlled events accompanying antral follicular development. Elevated basal androgen levels, as in PCOS, potentially affect oocyte quality. Current experiments in an in vitro follicle bioassay studied dose-effects of androstenedione and testosterone on FSH and hCG stimulated antral follicle growth and meiotic maturation. The addition of either androgens altered follicle's endogenous production of androstenedione, testosterone, estradiol, and progesterone and affected the oocyte's capacity to resume meiosis. Exposure to 200nM androstenedione induced an increased production of testosterone and estradiol. Exposure to a concentration of ≥200nM testosterone induced elevated levels of estradiol and progesterone. Significant dose-dependent negative effects on polar body extrusion were seen at concentrations of ≥200nM of either androgen. In addition, chromosome displacement on the metaphase plate was observed in oocytes obtained from androstenedione-treated follicles. Follicles exposed to a combination of 25mIU/ml FSH and 3mIU/ml hCG and elevated aromatizable androgens altered the steroid production profile, affected the follicular development and impaired oocyte meiotic competence.

Arsenate toxicity on the apices of Pisum sativum L. seedling roots: Effects on mitotic activity, chromatin integrity and microtubules

Arsenic (As) is one of the most toxic pollutants in the environment, where it severely affects both animal and plant growth. Despite the growing literature data on As effects on plant development, alterations induced by this element on meristem activity of the root have not been explored to any great extent. In the present study, short-term experiments with arsenate have been conducted on Pisum sativum L. seedlings to assess whether plant growth impairment is due to DNA/chromosome or mitotic microtubule damages. Root growth was studied by evaluating apical meristem activity and cell elongation. Mitotic aberrations, DNA fragmentation and microtubule organization of the apical cells were also analyzed. The results have shown that arsenate, at the lowest concentration (0.25 μM), slightly increases root growth and some related parameters, whilst the other concentrations have a dose-dependent negative effect on root growth, on the mitotic and labelling index (after bromo-deoxyuridine administration), and on the mitotic arrays of microtubule (through immunofluorescence). The main effects on mitosis occurred for 25 μM As. The percentage of metaphases increased, as did the irregular metaphases and c-mitoses. This was related to alterations in the mitotic spindles, which closely resemble those induced by colchicine. Chromosome breaks and ana/telophase bridges were virtually absent, whilst DNA fragmentation only increased from 25 μM arsenate onwards. These data point to a poor clastogenetic activity of As and implicate that microtubules are one of the main targets of As.

Effet de Mitragyna ciliata (MYTA) sur le système cardiovasculaire de rat

In this study, we evaluate the influence of a methanolic extract of Mitragyna ciliata (MYTA) [Rubiaceae] on the mechanics of isolated rat heart, thanks to improved Langerdorff’s device and carotid arterial pressure of rabbits with Ludwig’s device. MYTA, in concentrations ranging from 10−5 mg/ml to 5 × 10 mg/ml induces a drop in blood pressure with inotropic effect that varies from 0 to 35 ± 0.89% increase in concentrations ranging from 10−5 mg/ml at 5 × 10−1 mg/ml and a very high concentration of 1 mg/ml stops the heart with a magnitude of more than 50 ± 1.29% increase compared with the control. It also induces a dose-dependent negative chronotropic effect decreasing to 48 ± 0.79% before vanishing with the concentration of 1 mg/ml. In addition, MYTA gradually regulates the activity of cardiac arrhythmia induced by atropine and hypothermia. Thus, MYTA strengthens, regulates, and slows the activity of heart. MYTA induces dose-dependent hypotension ranging from 140 mmHg (normal) to 129 mmHg for a dose of 40-mg/kg body weight.

Characterization of the porcine constitutive androstane receptor (CAR) and its splice variants

Porcine constitutive androstane receptor (CAR; NR1I3) was cloned and compared for homology and activity with mouse and human CAR (mCAR, hCAR). Porcine CAR (pgCAR) was 86% and 75% homologous to hCAR at the nucleotide and protein levels.Five alternatively spliced variants of pgCAR were identified, each of which generated a truncated protein product. Real-time polymerase chain reaction (PCR) analyses showed that these variants were present in pig liver cDNA samples from 4.61% to 9.20% of total pgCAR.pgCAR and hCAR responded similarly to more ligands than did hCAR and mCAR. The known hCAR agonist (6-(4-chlorophenyl)imidazo[2,1-b][1,3]thiazole-5-carbaldehyde-O-(3,4-dichlorobenzyl)oxime (CITCO) activated pgCAR, while the murine agonist 1,4 bis[2-(3,5-dichloropyridyloxy)] benzene (TCPOBOP) had no effect. 5β-dihydrotestosterone was identified as a novel inverse agonist of both pgCAR and hCAR.pgCAR splice variant 2 (SV2) had a dose-dependent dominant negative effect on the activity of wild-type pgCAR in dual luciferase assays. SV2 had no effect against pgPXR (pregnane X receptor) or pgFXR (farnesoid X receptor) activity when using PXR- or FXR-specific reporters.

Negative chronotropic effect of proton pump inhibitors on frog-heart preparation

Proton pump inhibitors (PPIs) have been known to cause bradycardia. We evaluated the effect of three PPIs, i.e. omeprazole, rabeprazole and pantoprazole on the heart rate of frog. The in situ frog heart preparation was set up. Heart rate and amplitude of contraction were studied following administration of different doses of the three PPIs. Statistical analysis was done by using Graphpad statistical software system. After 1 mg of omeprazole and rabeprazole, and 2 mg pantoprazole, the heart rate was similar as compared to baseline (p >0.05). After 2 mg of omeprazole and rabeprazole, and 4 mg pantoprazole, the reduction in heart rate was significant (p <0.05). In addition, pantoprazole caused negative ionotropic effect. The three PPIs showed a dose-dependent negative chronotropic effect in the frog heart prepration.

Effect of the administration of young oak ( Quercus pyrenaica) leaves to cattle on ruminal fermentation

Two experiments were conducted to study the effects of feeding young Pyrenean oak leaves (OLs) to beef cattle on in vitro ruminal fermentation. A total of 12 ruminally cannulated Brown Swiss bulls were divided into experimental groups that were fed different quantities of OLs via the ruminal cannula (on average 0, 2.5, 5.2 and almost 10 kg fresh matter/animal per day; the treatments designated control, L-OL, H-OL and VH-OL, respectively). Batch cultures of rumen microorganisms and the in vitro gas production technique were used to study ruminal fermentation of two substrates (grass hay and OL) incubated with rumen inocula derived from each bull. Results showed not only a dose-dependent negative effect of feeding tannin-containing OL on ruminal fermentation of conventional feeds, such as the grass hay, but also improved fermentation of tannin-containing feeds, such as the OLs, in bulls fed moderate quantities of OLs ( i.e., L-OL and H-OL), which suggests adaptation of the rumen microbial population. Detrimental effects of the VH-OL treatment indicate that the high level of tannins in the rumen of bulls on the highest dose of OLs would have exceeded the capacity of the microorganisms to resist or detoxify them.

The 3-O-(3’,3’-dimethylsuccinyl) derivative of betulinic acid (DSB) inhibits the assembly of virus-like particles in HIV-1 Gag precursor-expressing cells

Background The 3- O-(3’,3’-dimethylsuccinyl) derivative of betulinic acid (DSB) blocks HIV-1 maturation by interfering with viral protease (PR) at the capsid (CA)-SP1 cleavage site, a crucial region in HIV-1 morphogenesis. Methods We analysed the effect of DSB on the assembly of HIV-1 Gag precursor (Pr55GagHIV) into membrane-enveloped virus-like particles (VLP) in baculovirus-infected cells expressing Pr55GagHIV, in a cellular context devoid of viral PR. Results DSB showed a dose-dependent negative effect on VLP assembly, with an IC50∼10 μM. The DSB inhibitory effect was p6-independent and was also observed for intracellular assembly of non-N-myristoylated Gag core-like particles. HIV-1 VLP assembled in the presence of DSB exhibited a lower stability of their inner cores upon membrane delipidation compared with control VLP, suggesting weaker Gag-Gag interactions. DSB also inhibited the assembly of simian immunodeficiency virus SIVmac251 VLP, although with a twofold lower efficacy (IC50∼20 μM). No detectable inhibitory activity was observed for murine leukaemia virus (MLV) VLP; however, fusion of the SP1-NC-p6 domains from HIV-1 to the matrix (MA)-CA domains from MLV conferred DSB sensitivity to the chimaeric Gag precursor Pr72GagMLV–HIV (IC50=30 μM). This observation suggested that the main DSB target on Pr55Gag was the SP1 domain, but the higher degree of DSB resistance for Pr72GagMLV–HIV compared with Pr55GagHIV implied that other upstream Gag region(s) might contribute to DSB reactivity. Conclusions Sequence alignment and three-dimensional modelling by homology of the CA-SP1-NC junction in HIV-1, SIVmac251 and Pr72GagMLV–HIV suggested that a higher hydrophilic character of the CA region immediately upstream to the HIV-1 CA-SP1 junction, as occurred in Pr72GagMLV–HIV, correlated with a lower DSB sensitivity.

Effect of immature oak (&lt;i&gt;Quercus pyrenaica&lt;/i&gt;) leaves intake on ruminal fermentation and adaptation of rumen microorganisms in cattle

Two experiments were conduoted to study the effect of the consumption of different amounts of immature $renean oak leaves (OL) by beef cattle oi in vitro ruminal fermentation and potential adaptauon ofrumen microorganisms. Atotal oftwelve ruminally cannulated young Brown Swiss bulls were divided in experimental groups that roceived differsnt amounts of OL v?a the ruminal cannula (on average 0,2.5,5.2 and almost 10 kg fresh matter per animal and day). The gas production technique was used to study in vitro fermentation of two substrates (grass hay and O[,) incubated with rumen inocrila derived from each bull. Results suggest not only a dose-dependent negative effect oftannins consumption on ruminal fermentation of common feeds (e.9., grass hay), but also an adaptation of rumen microbial populations from animals receiving moderate amounts of OL. The high level of tannins in the rumen of bulls that received tho highest amount of OL would have exceeded the ability of microorganisms to tolerate or detoxify them.

Long-lasting suppression of hippocampal cell proliferation and impaired cognitive performance by methotrexate in the rat

Methotrexate (MTX) is a cytostatic agent widely used in combination with other agents as adjuvant chemotherapy for breast cancer and is associated with cognitive impairment as a long-term side effect in some cancer patients. This paper aimed to identify a neurobiological mechanism possibly responsible for this cognitive impairment using an animal model. The first study explored the hypothesis that MTX reduces neuronal cell proliferation. A dose-dependent long-lasting decrease in hippocampal cell proliferation was shown with Ki-67 immunocytochemistry, following a single intravenous injection of MTX (37.5–300 mg/kg). Animals treated with MTX also showed a dose-dependent transient decrease in body weight gain. In the second study, the effect of MTX (250 mg/kg) on two spatial learning tasks was examined. Animals treated with MTX learned the Morris water maze task adequately; however, these animals showed a longer latency time to cross the platform location in the probe trial, reflecting an impairment of spatial memory function. In the novel object recognition task, animals treated with MTX failed to distinguish a novel object from a familiar one, indicating a decrease in the comparator function of the hippocampus. Our studies indicated that, in the rat, MTX has a dose-dependent negative effect on hippocampal cell proliferation, and on cognitive behavior. These findings suggest that adverse effects of certain cytotoxic agents on hippocampal cell proliferation may have a potential contributory role in cognitive impairment observed in humans after chemotherapy.

Association Between Amount Of Smoking With Chronic Cough And Sputum Production

Background: Smoking is a major cause of respiratory disease. We evaluated the association between the amount of chronic smoking with chronic cough and sputum production as a surrogate of pulmonary abnormalities Methods: 139 patients who underwent left ventricular ejection fraction measurement for clinical reasons, were evaluated for the presence of chronic cough and sputum production with reference to the length and amount of smoking. Results: The length and amount of smoking increased the risk of sputum production (smoking less than 10 pack years (9 of 48 18.8% vs smoking more than 10 pack years 38 of 108, 35.2%, OR: 1.3 CI 1.03-1.5, p=0.03). The length of smoking over 50 pack years vs less than 5 pack years was also significantly associated with chronic cough (24 of 31, 77.4% vs 22 of 52, 42.3%, OR: 4.7 CI: 1.7-12.7, p =0.002). Furthermore the mean length of smoking was significantly longer in patients with chronic cough (34.9  38.2 vs 49.1  40.2, p=0.03) or increased sputum production (34.6 39 vs 56.0  40.4, p=0.002). Conclusion: Increasing in length and amount of smoking is associated with increase risk for chronic cough and sputum production consistent with dose dependent negative effect of chronic smoking.

EEG spectral power and cognitive performance during sleep inertia: The effect of normal sleep duration and partial sleep deprivation

Sleep inertia (SI) is a transient period occurring immediately after awakening, usually characterized by performance decrement. When sleep is sufficient, SI is moderate, and produces few or no deficit. When it is associated with prior sleep deprivation, SI shows dose-dependent negative effects on cognitive performance, especially when subjects have been awaken in slow wave sleep (SWS). In the present study, spectral analysis was applied during the last 10 min before and the first 10 min after awakening, and during 1 h after awakening while subjects performed the Stroop test. Seventeen subjects were divided into a Control group who slept 8 h, and a Sleep Deprived group who slept only 2 h. The results show that performance was normal in the Control group, whereas reaction time was increased during the first half hour and error level during the second half hour in the Sleep Deprived group. Spectral analysis applied on the waking EEG during the whole test session showed that alpha activity was increased in both groups, but theta power only in the Sleep Deprived group. There was a high positive correlation in sleep deprived subjects between delta power during the last 10 min of sleep and subsequent performance decrement in speed and accuracy. Comparison of individual records showed a high positive correlation between spectral power before and after awakening in the Control group (generally in the sense of an increased frequency band), but no correlation was found in the Sleep Deprived group who exhibited a rather disorganized pattern. We discuss these results in terms of incoherence in the EEG continuity during sleep offset after prior sleep loss, which could partly account for the performance decrement observed during SI in sleep deprived subjects.