Convenient method for the determination of arginine and its related compounds in rumen fluid by reversed-phase high-performance liquid chromatography

In order to clarify arginine (Arg) metabolism by rumen microorganisms and by the tissues of ruminant animals, a convenient method for the simultaneous determination of Arg, citrulline (Cit), ornithine (Orn), proline (Pro) and 5-aminovaleric acid (5AV), and 4-aminobutyric acid (4AB) and lysine (Lys), incidentally, in goat rumen fluid was established by reversed-phase high-performance liquid chromatography (RP-HPLC). The separation was carried out by stepwise isocratic elution with two mobile phases (solvent A and solvent B) on a LiChrospher 100 RP-18 column (150×4.6 mm I.D., 5 μm particle size) equipped with a guard column (4.0×4 mm, 5 μm particle size). Solvent A is composed of acetonitrile–sodium citrate buffer (pH 7.2) (15:85, v/v) containing tetrahydrofuran (5 ml/100 ml), with solvent B comprising acetonitrile–sodium citrate buffer (pH 5.4) (40:60, v/v). Five compounds (Cit, Arg, Pro, 4AB and 5AV) were separated within 33 min in solvent A and the other two (Orn and Lys) in solvent B. Solvent A was automatically switched to solvent B with the help of a valve controller. Complete separation needs 62 min after sample injection in a single chromatogram. Samples were derivatized with 9-fluorenylmethyloxycarbonyl chloride (FMOC-Cl) and detected on a fluorescence detector at excitation and emission wavelengths of 263 and 611 nm, respectively. The minimum detectable concentrations (μM) (signal-to-noise ratio, S/N 3:1) of these compounds were: 0.65 for Cit, 0.65 for Arg, 1.9 for Pro, 1.3 for 4AB, 1.9 for 5AV, 0.12 for Orn and 0.48 for Lys. When applied to rumen fluid from goats, recoveries of all compounds added to the rumen fluid were 96.6–100.6% for an intra-day study and 93.9–99.4% for inter-day (5 days) studies. The average contents of Orn, 5AV and Lys in the rumen fluid of three goats before morning feeding were 7.3, 13.5 and 3.6 μM, but Cit, Arg, Pro, and 4AB were not found, although all these four compounds were detected 1 h after feeding. Pro (390 μM) and 5AV (497.6 μM) were highest 1 h after feeding and then decreased. Orn levels before morning feeding were most similar to those after feeding.     

Drug susceptibility of Plasmodium falciparum from polyclonal isolates

Msp-1 and Msp-2 genes, each present as a unique copy in the genome of Plasmodium, contain polymorphic repeats in bloc 2. We studied allelic polymorphism of Msp-1 and Msp-2 by amplifying bloc 2 with a fluorescent primer, and analysing the fragment generated. We validated this method by mixing two cloned strains: chloroquine-susceptible HB3-Honduras and chloroquine-resistant FCM29-Cameroon. This method was then used to quantify the clones in natural isolates of 19 infected persons during quinine treatment. The fragment analysis method detects efficiently clone numbers and the proportions of each in isolates.     

IGF-1 activates hEAG K(+) channels through an Akt-dependent signaling pathway in breast cancer cells: role in cell proliferation

Previous work from our laboratory has shown that human ether à go-go (hEAG) K(+) channels are crucial for breast cancer cell proliferation and cell cycle progression. In this study, we investigated the regulation of hEAG channels by an insulin-like growth factor-1 (IGF-1), which is known to stimulate cell proliferation. Acute applications of IGF-1 increased K(+) current-density and hyperpolarized MCF-7 cells. The effects of IGF-1 were inhibited by hEAG inhibitors. Moreover, IGF-1 increased mRNA expression of hEAG in a time-dependent manner in parallel with an enhancement of cell proliferation. The MCF-7 cell proliferation induced by IGF-1 is inhibited pharmacologically by Astemizole or Quinidine or more specifically using siRNA against hEAG channel. Either mitogen-activated protein kinase (MAPK) or phosphatidylinositol 3-kinase (PI3K) are known to mediate IGF-1 cell proliferative signals through the activation of extracellular signal-regulated kinase 1/2 (Erk 1/2) and Akt, respectively. In MCF-7 cells, IGF-1 rapidly stimulated Akt phosphorylation, whereas IGF-1 had little stimulating effect on Erk 1/2 which seems to be constitutively activated. The application of wortmannin was found to block the effects of IGF-1 on K(+) current. Moreover, the inhibition of Akt phosphorylation by the application of wortmannin or by a specific reduction of Akt kinase activity reduced the hEAG mRNA levels. Taken together, our results show, for the first time, that IGF-1 increases both the activity and the expression of hEAG channels through an Akt-dependent pathway. Since a hEAG channel is necessary for cell proliferation, its regulation by IGF-1 may thus play an important role in IGF-1 signaling to promote a mitogenic effect in breast cancer cells.     

Dynamic Stability and Risk of Tripping during the Timed Up and Go Test in Hemiparetic and Healthy Subjects

Background

The Timed Up and Go (TUG) test is often used to estimate risk of falls. Foot clearance and displacement of the center of mass (COM), which are related to risk of tripping and dynamic stability have never been evaluated during the TUG. Accurate assessment of these parameters using instrumented measurements would provide a comprehensive assessment of risk of falls in hemiparetic patients. The aims of this study were to analyze correlations between TUG performance time and displacement of the COM and foot clearance in patients with stroke-related hemiparesis and healthy subjects during the walking and turning sub-tasks of the TUG and to compare these parameters between fallers and non-fallers.

Methods

29 hemiparetic patients and 25 healthy subjects underwent three-dimensional gait analysis during the TUG test. COM and foot clearance were analyzed during the walking and turning sub-tasks of the TUG.

Results

Lateral displacement of the COM was greater and faster during the walking sub-tasks and vertical displacement of the COM was greater during the turn in the patients compared to the healthy subjects (respectively p<0.01 and p<0.05). Paretic foot clearance was greater during walking and displacement of the COM was slower during the turn in the patients (p<0.01). COM displacement and velocity during the turn were correlated with TUG performance in the patients, however, vertical COM displacement was not. These correlations were significant in the healthy subjects. There were no differences between COM parameters or foot clearance in fallers and non-fallers.

Discussion and Conclusion

Hemiparetic patients are less stable than healthy subjects, but compensate with a cautious gait to avoid tripping. Instrumented analysis of the TUG test appears relevant for the assessment of dynamic stability in hemiparetic patients, providing more information than straight-line gait.     

Incidence,Carriage and Case-Carrier Ratios for Meningococcal Meningitis in the African Meningitis Belt: A Systematic Review and Meta-Analysis

BackgroundTo facilitate the interpretation of meningococcal meningitis epidemiology in the “African meningitis belt”, we aimed at obtaining serogroup-specific pooled estimates of incidence, carriage and case-carrier ratios for meningococcal meningitis in the African meningitis belt and describe their variations across the endemic, hyperendemic and epidemic context.MethodsWe conducted a systematic review and meta-analysis of studies reporting serogroup-specific meningococcal meningitis monthly incidence and carriage in the same population and time period. Epidemiological contexts were defined as endemic (wet season, no epidemic), hyperendemic (dry season, no epidemic), and epidemic (dry season, epidemic).FindingsEight studies reporting a total of eighty pairs of serogroup-specific meningococcal meningitis incidence and carriage estimates were included in this review. For serogroup A, changes associated with the transition from endemic to hyperendemic incidence and from hyperendemic to epidemic incidence were 15-fold and 120-fold respectively. Changes in carriage prevalence associated with both transitions were 1-fold and 30-fold respectively.
For serogroup W and X, the transition from endemic to hyperendemic incidence involved a 4-fold and 1•1-fold increase respectively. Increases in carriage prevalence for the later transition were 7-fold and 1•7-fold respectively. No data were available for the hyperendemic-epidemic transition for these serogroups. Our findings suggested that the regular seasonal variation in serogroup A meningococcal meningitis incidence between the rainy and the dry season could be mainly driven by seasonal change in the ratio of clinical cases to subclinical infections. In contrast appearance of epidemic incidences is related to a substantial increase in transmission and colonisation and to lesser extent with changes in the case-carrier ratio.ConclusionSeasonal change in the rate of progression to disease given carriage together with variations in frequency of carriage transmission should be considered in models attempting to capture the epidemiology of meningococcal meningitis and mainly to predict meningitis epidemics in the African meningitis belt.     

Use of Random Amplified Polymorphic DNA Analysis for Economically Important Food Crops

The objective of this review is to summarize numerous studies on the use of the random amplified polymorphic DNA （RAPD） technique on rice, corn, wheat, sorghum, barley, rye, and oats to examine its feasibility and validity for assessment of genetic variation, population genetics, mapping, linkage and marker assisted selection, phylogenetic analysis, and the detection of somaclonal variation. Also we discuss the advantages and limitations of RAPD. Molecular markers have entered the scene of genetic improvement in different fields of agricultural research. The simplicity of the RAPD technique made it ideal for genetic mapping, plant and animal breeding programs, and DNA fingerprinting, with particular utility in the field of population genetics.     

Bioinformatics and data mining in proteomics

Proteomic studies involve the identification as well as qualitative and quantitative comparison of proteins expressed under different conditions, and elucidation of their properties and functions, usually in a large-scale, high-throughput format. The high dimensionality of data generated from these studies will require the development of improved bioinformatics tools and data-mining approaches for efficient and accurate data analysis of biological specimens from healthy and diseased individuals. Mining large proteomics data sets provides a better understanding of the complexities between the normal and abnormal cell proteome of various biological systems, including environmental hazards, infectious agents (bioterrorism) and cancers. This review will shed light on recent developments in bioinformatics and data-mining approaches, and their limitations when applied to proteomics data sets, in order to strengthen the interdependence between proteomic technologies and bioinformatics tools.     

Modulation of dendritic cell function by naive and regulatory CD4+ T cells

The consequences of interactions between dendric cells (DCs) and either naive CD4+ T cells or regulatory CD4+CD25+ T cells on the expression of proinflammatory IL-6 and anti-inflammatory IL-10 in DC were examined over a period of 12 h, spanning the time frame during which stable T cell-DC interactions shape the development of tolerance and immunity in vivo. We demonstrate that the basal production of IL-6 and IL-10, which is initiated following DC stimulation with LPS, is modified in distinctly different ways by interaction with the two T cell populations. Naive CD4 T cells skew DC cytokine production toward IL-6 and suppress IL-10, whereas CD4+CD25+ T cells have the opposite effect. CD8 T cells or memory CD4 T cells do not influence basal cytokine production by stimulated DC. The effect of CD4+CD25+ T cells is dominant in coculture with naive CD4 T cells as long as inflammatory LPS is absent; the addition of LPS abrogates the suppression of IL-6. However, the modulating influence of CD4+CD25+ T cells remains evident in the enhancement of IL-10 production. Thus, mutual interactions between DC and CD4+ T cell subpopulations following contact with pathogens are likely to influence the strength and quality of incipient immune responses in the local microenvironment.     

K+ Channel Expression in Human Breast Cancer Cells: Involvement in Cell Cycle Regulation and Carcinogenesis

K⁺ channels are a most diverse class of ion channels in the plasma membrane and are distributed widely throughout a variety of cells including cancer cells. Evidence has been accumulating from fundamental studies indicating that tumour cells possess various types of K⁺ channels and that these K⁺ channels play important roles in regulating tumor cell proliferation, cell cycle progression and apoptosis. Moreover, a significant increase in K⁺ channel expression has been correlated with tumorigenesis, suggesting the possibility of using these proteins as transformation markers and perhaps reducing the tumor growth rate by selectively inhibiting their functional activity. Significant progress has been made in defining the properties of breast K⁺ channels, including their biophysical and pharmacological properties and distribution throughout different phases of the cell cycle in breast cell line MCF-7. This review aims to provide a comprehensive overview of the current state of research into K⁺ channels/currents in breast cancer cells. The possible mechanisms by which K⁺ channels affect tumor cell proliferation and cell cycle progression are discussed.     

Effects of chloramphenicol on brain energy metabolism using 31P spectroscopy: influences on sleep-wake states in rat

Effects of chloramphenicol (antibiotic inhibiting complex-1 of respiratory chain) and thioamphenicol (TAP, a structural analog of CAP inactive on complex-1) were examined on cerebral energy metabolites and sleep-wake cycle architecture in rat. In the first group, animals were chronically equipped with a cranial surface resonator and ³¹P spectroscopic measurements were performed using a 2 T magnetic resonance spectrometer (operating frequency 34.46 MHz). CAP administration (400 mg/kg, tail vein, light period) induced deficits in phosphocreatine (−30%, p  < 0.01) and ATP (−40%, p  < 0.01), whereas TAP (400 mg/kg) had no effect. In the second group, animals were chronically implanted with polygraphic electrodes for EEG and electromyogram recordings. CAP administered intraperitoneally at light-onset reduced rapid-eye movement (REM) sleep (−60% in the first 6 h of light period, p  < 0.01), increased waking state (+65% in the first 6 h of light period, p  < 0.01), and slightly affected slow-wave sleep (SWS). During waking state, θ and σ power bands of the EEG were, respectively, increased and decreased ( p  < 0.05). During SWS, delta power band was reinforced ( p  < 0.05), while θ, α, and σ bands were decreased ( p  < 0.05). No changes occurred during REM sleep. TAP had no effect on sleep-wake states and spectral components of the EEG. Overall, these data indicate that REM sleep occurrence is linked to an aerobic production of ATP.