Parturition in beef cows following administration of porcine relaxin at ten days prepartum

Administration of procine relaxin (pRLX) to heifers 5 d prepartum has been reported to expedite parturition. Thirty-eight mature crossbred beef cows were randomly assigned to one of three treatment groups. Control animals (C; n = 13) received an intramuscular (i.m.) injection of 2 ml corn oil and 2 ml i.m. phosphate-buffered saline (PBS) 24 h later; relaxin treated animals (RLX; n = 13) received 2 ml i.m. corn oil and 1.0 mg i.m. pRLX 24 h later; estradiol-relaxin treated animals (E-RLX; n = 12) received 20 mg i.m. estradiol benzoate (EB) and 1.0 mg i.m. pRLX 24 h later. Treatment with pRLX occurred at 272.6+/-0.14 d of gestation. The pRLX had been purified to homogeneity from porcine ovaries collected during late pregnancy and was determined to have >/=3000 U/mg by the mouse interpubic ligament bioassay. Peripheral blood samples were collected from all cows at 0, 4, 8 and 24 h, respective to corn oil or EB administration, and assayed for plasma estradiol-17beta. At 24 h post administration of EB, plasma estradiol-17beta concentrations were 48.0+/-10.5 pg/ml for C and RLX cows and 178.5+/-14.8 pg/ml for E-RLX cows. There were no treatment effects (P>/=0.10) for elapsed time from treatment to parturition (304.2+/-22.4 h), gestation length (285.2+/-0.9 d), calving difficulty score (1.05+/-0.04), calf vigor score (1.05+/-0.04) or calf birth weight (38.0+/-0.88 kg). Additionally, there were no retained placental membranes in any cows. Administration of pRLX intramuscularly to beef cows at 10 d before expected parturition was not effective in inducing premature parturition. Furthermore, the effectiveness of pRLX in inducing parturition was not enhanced by pretreatment with estradiol benzoate.     

脑室注射白介素-1β引起的热痛敏作用

实验在SD大鼠上应用脑室微量注射和辐射热测痛的方法,研究了脑内微量注射白介素－1β对大鼠痛阈的影响。实验大鼠分为给药组和对照组,在给药组大鼠脑室注射不同剂量的白介素－1β（5、50和500pg/kg),对照组大鼠脑室注射配药液。白介素－1受体拮抗剂（IL－1ra,50ng/kg)在脑室注射白介素－1β前20min给予。实验以大鼠对光热刺激引起的缩爪反射潜伏期为痛阈指标。结果表明,脑室注射白介素－1β可显著缩短大鼠对光热刺激的缩爪反射潜伏期,并具有剂量依赖性关系。脑室给予500pg/kg的白介素－1β 20min后,大鼠对光热刺激的缩爪反射潜伏期显著缩短,40min时达峰值,然后逐渐恢复。该作用可被白介素－1β受体拮抗剂阻断。结果提示脑中白介素－1β可通过作用于白介素－1受体引起热痛敏作用。     

Validation and implementation of a method for determination of bryostatin 1 in human plasma by using liquid chromatography/tandem mass spectrometry

A new sensitive and specific method using liquid chromatography/tandem mass spectrometry for determination of bryostatin 1 was developed and validated. Sample pretreatment involved a double liquid-liquid extraction step with a mixture of acetonitrile/n-butyl chloride (1/4, v/v). Separation of the compound of interest, including the internal standard paclitaxel, was achieved on a Waters X-Terra C18 (50 x 2.1 mm i.d., 3.5 microm) analytical column with acetonitrile/water mobile phase (80:20, v/v) containing 0.1% formic acid using isocratic flow at 0.15 mL/min for 13 min. The analytes of interest were monitored by tandem mass spectrometry with electrospray positive ionization. The linear calibration curves were generated over the range of 50-2000 pg/mL with values for the coefficient of determination of >0.99. The values for both within-day and between-day precision and accuracy were <15%. This method was used to characterize the plasma pharmacokinetics of bryostatin 1 at doses of 20 microg/m2) to optimize treatment with this agent.     

Application of a sensitive liquid chromatographic/tandem mass spectrometric method to pharmacokinetic study of nalmefene in humans

A sensitive, specific and rapid liquid chromatographic/tandem mass spectrometric (LC/MS/MS) method was developed and validated for quantification of nalmefene in human plasma. An aliquot of 200 microL plasma sample was simply precipitated by 400 microL methanol. Separation of nalmefene and the internal standard hydromorphone from the interferences was achieved on a C(18) column followed by MS/MS detection. The analytes were monitored in the positive ionization mode with a TurboIonspray source. The method had a total chromatographic run time of 4.5 min and linear calibration curves over the concentration range of 10-5000 pg/mL. The lower limit of quantification (LLOQ) was 10 pg/mL. The intra- and inter-day precision was less than 10.1% determined from QC samples at concentrations of 30, 300 and 4500 pg/mL, and the accuracy was within +/-3.4%. As the method was more sensitive (10 times higher) than those reported previously, we investigated the pharmacokinetics of nalmefene in healthy volunteers after a single intravenous injection of low dose (30 microg) of nalmefene hydrochloride for the first time.     

Simultaneous determination of global DNA methylation and hydroxymethylation levels by hydrophilic interaction liquid chromatography-tandem mass spectrometry

Methylation of DNA at the 5-position of cytosine (Cyt) is a well-studied epigenetic pathway implicated in gene silencing and embryogenesis. Recently, in addition to 5-methylcytosine (5mC), substantial amounts of 5-hydroxymethylcytosine (5hmC) have been detected in certain mammalian tissues. Here, we developed and validated a hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) method for the simultaneous determination of Cyt, 5mC, and 5hmC levels in biological samples. DNA was extracted with phenol-chloroform, hydrolyzed using 88% formic acid at 140 °C, separated using a bridged ethylene hybrid HILIC column, and analyzed by tandem MS. The linearity was established over the concentration range of 1 to 500 ng/mL for Cyt, 0.2 to 100 ng/mL for 5mC, and 0.1 to 50 ng/mL for 5hmC, and the correlation coefficients were all >0.99. Limits of detection were 1 pg/mL for Cyt, 45 pg/mL for 5mC, and 57 pg/mL for 5hmC, and the limit of quantification values for Cyt, 5mC, and 5hmC were 2 pg/mL, 90 pg/mL, and 100 pg/mL, respectively. The relative standard deviation (RSD) of the intraday precision ranged from 1.87% to 4.84% and the interday precision from 2.69% to 4.98%. The recovery of the method varied from 88.25% to 104.39%. The method was then applied to the analysis of DNA from biological samples, establishing its potential for helping researchers understand the roles of modified nucleobases in DNA.     

Sensitive and selective liquid chromatography/tandem mass spectrometry methods for quantitative analysis of 1-methyl-4-phenyl pyridinium (MPP+) in mouse striatal tissue

The systemic administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to mice produces a reliable and selective degeneration of the nigrostriatal pathway, a hallmark feature of Parkinson's disease (PD). Determining the brain concentrations of 1-methyl-4-phenyl pyridium (MPP+), the neurotoxic metabolite of MPTP, is critical for evaluating drugs designed to potentially treat PD. We have developed sensitive and specific quantitative methods for the determination of MPP+ in mouse striatal tissue by liquid chromatography/tandem mass spectrometry. The separations were carried out based on reversed phase chromatography or cation exchange chromatography with volatile elution buffer. Neutralizing the brain sample with 0.2M phosphate buffer successfully solved a high-performance liquid chromatography (HPLC) peak tailing of MPP+ in brain extracts with 0.4M perchloric acid (HClO4) under the reversed phase HPLC conditions, which significantly improved the sensitivity of the method. The HPLC peak shape of MPP+ using cation exchange chromatography was not affected by the pH of the samples. Optimization of electrospray ionization (ESI) conditions for the quaternary ammonium compound MPP+ established the limits of detection (LOD) (S/N=3) at 0.34pg/mg tissue and 0.007pg/mg tissue (5microl of injection) using the reversed phase liquid chromatography/tandem mass spectrometry (LC/MS/MS) and the cation exchange LC/MS/MS, respectively. Both methods were selective, precise (%R.S.D.<6%), and sensitive over a range of 0.001-1ng/mg tissue. The cation exchange method showed greater sensitivity and tolerance to low pH samples than the reversed phase method. The developed methods were applied to monitoring changes in MPP+ concentrations in vivo. Two reference agents, R-(-) Deprenyl and MK-801, known to alter the concentration of MPP+ in MPTP treated mice were evaluated.     

Development and validation of bioanalytical methods for Imidafenacin (KRP-197/ONO-8025) and its metabolites in human plasma by liquid chromatography-tandem mass spectrometry

Imidafenacin (KRP-197/ONO-8025, IM), 4-(2-methyl-1H-imidazol-1-yl)-2,2-diphenylbutanamide, is a new antimuscarinic agent currently under application for the indication of treatment of overactive bladder in Japan. We developed and validated the sensitive and selective bioanalytical methods for the extremely low levels of IM and its metabolite, M-2 (Method 1), M-4 (Method 2) and M-9 (Method 3) in human plasma using liquid chromatography-tandem mass spectrometry (LC-MS/MS). In each method, plasma sample was extracted by solid phase extraction, separated on a semi-micro high performance liquid chromatography column and detected by tandem mass spectrometer with an atmospheric pressure chemical ionization or ionspray interface. Selected reaction monitoring mode was used for quantification. Each method was found to have acceptable accuracy, precision, stability, selectivity and linearity over the concentration range of 10-500 pg/mL for IM and M-2, 10-1000 pg/mL for M-4 and 50-5000 pg/mL for M-9. Using these analytical methods, concentration profiles of IM and its metabolites in human plasma were successfully determined even in the low pg/mL levels after oral administration of IM at the therapeutic dosage of 0.1 mg.     

Heteroplasmy and evidence for recombination in the mitochondrial control region of the flatfish Platichthys flesus

The general assumption that mitochondrial DNA (mtDNA) does not undergo recombination has been challenged recently in invertebrates. Here we present the first direct evidence for recombination in the mtDNA of a vertebrate, the flounder Platichthys flesus. The control region in the mtDNA of this flatfish is characterized by the presence of a variable number of tandem repeats and a high level of heteroplasmy. Two types of repeats were recognized, differing by two C-T point mutations. Most individuals carry a pure "C" or a pure "T" array, but one individual showed a compound "CT" array. Such a compound array is evidence for recombination in the mtDNA control region from the flounder.     

Sensitive and accurate analyses of free 3-nitrotyrosine in exhaled breath condensate by LC-MS/MS

The quantitative determination of 3-nitro-l-tyrosine, a biological marker for inflammatory processes, in exhaled breath condensate (EBC) is described. The clean-up and preconcentration was performed by solid phase extraction (SPE). After liquid chromatography the specific detection was performed by tandem mass spectrometry using electron spray ionisation and selected reaction monitoring (SRM). 13C9-3-nitrotyrosine was used as an internal standard. For reliability, tests for the precision of the method, the losses during preparation, a test for nitrating artifacts and the comparibility of calibrants in EBC and buffer solution were performed. The calibration of the method was linear over a range of 10-500 pg/mL. The within-run coefficients of variation (CV) of the samples were found to be 8.4% at 25 pg/mL and 8.3% at 250 pg/mL. The day-to-day CV was found to be 11.2%. The limit of quantification was 3.9 pg/mL. The losses during preparation were 15%. The discrepancy between the calibration with EBC and buffer solution was below 10%. No artificial production of 3-nitrotyrosine was observed during the procedure. The application of the method on the EBC samples of healthy smokers (N=10) and non-smokers (N=10) showed no difference between the two groups. The concentration of 3-nitrotyrosine ranged between the limit of quantification and 184 pg/mL and was distinctly lower than data detected by an immunoassay procedure. The procedure was proven to be accurate, sensitive and in contrast to GC methods less elaborate and is recommended for the determination of 3-nitrotyrosine in exhaled breath condensate.     

Functional Characterisation of the Maturation of the Blood-Brain Barrier in Larval Zebrafish

Zebrafish are becoming increasingly popular as an organism in which to model human disease and to study the effects of small molecules on complex physiological and pathological processes. Since larvae are no more than a few millimetres in length, and can live in volumes as small as 100 microliters, they are particularly amenable to high-throughput and high content compound screening in 96 well plate format. There is a growing literature providing evidence that many compounds show similar pharmacological effects in zebrafish as they do in mammals, and in particular humans. However, a major question regarding their utility for small molecule screening for neurological conditions is whether a molecule will reach its target site within the central nervous system. Studies have shown that Claudin-5 and ZO-1, tight-junction proteins which are essential for blood-brain barrier (BBB) integrity in mammals, can be detected in some cerebral vessels in zebrafish from 3 days post-fertilisation (d.p.f.) onwards and this timing coincides with the retention of dyes, immunoreactive tracers and fluorescent markers within some but not all cerebral vessels. Whilst these findings demonstrate that features of a BBB are first present at 3 d.p.f., it is not clear how quickly the zebrafish BBB matures or how closely the barrier resembles that of mammals. Here, we have combined anatomical analysis by transmission electron microscopy, functional investigation using fluorescent markers and compound uptake using liquid chromatography/tandem mass spectrometry to demonstrate that maturation of the zebrafish BBB occurs between 3 d.p.f. and 10 d.p.f. and that this barrier shares both structural and functional similarities with that of mammals.     

Isolation and characterization of trichothecin from corn cultures of Fusarium graminearum MRC 1125

Trichothecin was isolated and purified from corn cultures of a toxic strain of Fusarium graminearum. This strain, designated MRC 1125, was obtained from corn in southern Africa. The brine shrimp toxicity assay was used throughout the isolation procedure to monitor the toxicity of the fractions. The compound was characterized by detailed 1H (500-MHz) and 13C (125-MHz) nuclear magnetic resonance spectroscopy and mass spectrometry. This is the first report of the production of trichothecin by a Fusarium species.     

Isolation and characterization of trichothecin from corn cultures of Fusarium graminearum MRC 1125.

Trichothecin was isolated and purified from corn cultures of a toxic strain of Fusarium graminearum. This strain, designated MRC 1125, was obtained from corn in southern Africa. The brine shrimp toxicity assay was used throughout the isolation procedure to monitor the toxicity of the fractions. The compound was characterized by detailed 1H (500-MHz) and 13C (125-MHz) nuclear magnetic resonance spectroscopy and mass spectrometry. This is the first report of the production of trichothecin by a Fusarium species.     

Microdose clinical trial: quantitative determination of fexofenadine in human plasma using liquid chromatography/electrospray ionization tandem mass spectrometry

A sample treatment procedure and high-sensitive liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method for quantitative determination of fexofenadine in human plasma was developed for a microdose clinical trial with a cold drug, i.e., a non-radioisotope-labeled drug. Fexofenadine and terfenadine, as internal standard, were extracted from plasma samples using a 96-well solid-phase extraction plate (Oasis HLB). Quantitation was performed on an ACQUITY UPLC system and an API 5000 mass spectrometer by multiple reaction monitoring. Chromatographic separation was achieved on an XBridge C18 column (100 mm x 2.1 mm i.d., particle size 3.5 microm) using acetonitrile/2 mM ammonium acetate (91:9, v/v) as the mobile phase at a flow rate of 0.6 ml/min. The analytical method was validated in accordance with the FDA guideline for validation of bioanalytical methods. The calibration curve was linear in the range of 10-1000 pg/ml using 200 microl of plasma. Analytical method validation for the clinical dose, for which the calibration curve was linear in the range of 1-500 ng/ml using 20 microl of plasma, was also conducted. Each method was successfully applied for making determinations in plasma using LC/ESI-MS/MS after administration of a microdose (100 microg solution) and a clinical dose (60 mg dose) in eight healthy volunteers.     

A sensitive and reliable quantification method for mouse interleukin-12 p70 based on fluorometric sandwich ELISA (FS-ELISA)

Interleukin-12 (IL-12) p70 is an important cytokine secreted by antigen-presenting cells in response to antigenic stimulation; it is a heterodimer of p35 and p40 subunits. Here, we report a new, highly sensitive, and reliable method that employs fluorometric sandwich ELISA for quantification of the mouse IL-12 (moIL-12) p70 protein. Our method could quantify moIL-12 p70 in the range of approximately 0.5 to 500 pg/ml. In the assay, no signals were produced by the moIL-12 p40 monomer, homodimer [(p40)2], or mouse IL-23 even up to a concentration of 500 pg/ml; this ensures that our assay has a high specificity for moIL-12 p70. To demonstrate that our method can determine natural moIL-12 in real physiological/pathological samples, we monitored the moIL-12 p70 secretion from peritoneal exudative cells after lipopolysaccharide (LPS) stimulation. IL-12 p70 secretion as early as 3h after LPS stimulation was reliably detected due to the high sensitivity of the method.     

Semi-automated determination of plasma stability of drug discovery compounds using liquid chromatography-tandem mass spectrometry

A simple procedure for the measurement of stability of drug candidates in plasma was developed to eliminate the traditional labor-intensive and time-consuming sample preparation procedures that are typically used for these studies. The procedure makes use of a thermostatic autosampler as an incubator combined with the direct plasma injection method based on high-performance liquid chromatography (HPLC) coupled to tandem mass spectrometry (MS-MS). Untreated human, monkey, mouse and rat plasma containing the test compound was directly injected into a mixed-function column for on-line protein removal and chromatography. The test compound and its biotransformation product were separated via HPLC and monitored using the tandem mass spectrometer. The need for adequate chromatographic separation of the test compound (M) from its carboxylic acid metabolite (M+1) is demonstrated. Plasma samples from four different species at specified incubation temperatures were sequentially assayed in one analytical procedure. The injection-to-injection time was about 6 min. The peak responses of the test compound in individual plasma samples were repeatedly determined every 24 min. The retention times and peak shape of all analytes were found to be consistent throughout the experiments. The stability of the test compound in plasma was found to be a function of animal species, incubation time and temperature. The test compound was rapidly degraded in rat plasma at 37 degrees C, but it could be stabilized by adding sodium thiosulfate.     

An automated SPE/LC/MS/MS method for the analysis of cocaine and metabolites in whole blood

As laboratories are called upon to develop novel, fast, and sensitive methods, here we present a completely automated method for the analysis of cocaine and its metabolites (benzoylecgonine, ecgonine methyl ester, ecgonine and cocaethylene) from whole blood. This method utilizes an online solid-phase extraction (SPE) with high performance liquid chromatographic separation and tandem mass spectrometric detection. Pretreatment of samples involve only protein precipitation and ultracentrifugation. An efficient online solid-phase extraction (SPE) procedure was developed using Hysphere MM anion sorbent. A gradient chromatography method with a Gemini C6-Phenyl (50mmx3.00mm i.d., 5microm) column was used for the complete separation of all components. Analysis was by positive ion mode electrospray ionization tandem mass spectrometry, using multiple reaction monitoring (MRM) to enhance the selectivity and sensitivity of the method. For the analysis, two MRM transitions are monitored for each analyte and one transition is monitored for each internal standard. With a 30-microL sample injection, linearity was analyte dependent but generally fell between 8 and 500ng/mL. The limits of detection (LODs) for the method ranged from 3 to 16ng/mL and the limits of quantitation (LOQs) ranged from 8 to 47ng/mL. The bias and precision were determined using a simple analysis of variance (ANOVA: single factor). The results demonstrate bias as <7%, and %precision as <9% for all components at each QC level.     

Determination of the GABAB receptor agonist CGP 44532 (3-amino-2-hydroxypropylmethylphosphinic acid) in rat plasma after pre-column derivatization by micro-high-performance liquid chromatography combined with negative electrospray tandem mass spectrometry

An assay, based on pre-column derivatization and micro-high-performance liquid chromatography–tandem mass spectrometry, was developed for the determination of the GABA_B agonist CGP 44532 in rat plasma. CGP 44532, a highly polar 3-amino-2(S)-hydroxypropylmethylphosphinic acid, presented difficulties in developing a chromatographic method for the analysis of the compound in rat plasma. Instead of analyzing the target compound directly, it was derivatized prior to separation to a 4-nitrobenzylcarbamate isopropyliden derivative. In order to reach the required quantitation limit, on-line solid-phase extraction was utilized for sample clean-up and reversed-phase micro-column high-performance liquid chromatography, for separation of the plasma samples. The separated compounds were detected by negative electrospray tandem mass spectrometry in selected reaction monitoring mode. The derivatives show good chromatographic and mass spectrometric properties and both the target compound and the internal standard, could be eluted as symmetrical peaks with good signal/noise ratio. The MS–MS detection was selective and sensitive due to the straight fragmentation pattern. After injection of 200-μl sample aliquots, the limit of quantification was 10 ng ml⁻¹. The analytical assay is useable in the range of 10–500 ng ml⁻¹.     

Characterization of an in vitro method for demonstrating thyrotropin-releasing hormone-stimulated prolactin secretion.

Anterior pituitaries of normal adult male rats were subjected to synthetic thyrotropin-releasing hormone (TRH) treatment in an acute incubation system which employed pretreatment of the glands with plasma obtained from the donor animals. Following a 60-min preincubation period in a 1:1 mixture of Krebs-Ringer bicarbonate buffer (KRB) and plasma, media and hemipituitary prolactin (PRL) concentrations were significantly (p less than 0.01) increased after a 40-min treatment with 500 pg TRH. The TRH effect was absent among hemipituitaries preincubated in KRB alone. Plasma obtained from older donors was more potent than was plasma from younger rats in this effect. TSH secretion was markedly increased by 500 pg TRH, whether or not plasma preincubation was employed. A dose response of PRL release to concentrations of TRH from 100 pg to 6.0 ng was observed. Crude extracts of median eminence also effected enhanced PRL release using the plasma preincubation technique. The results suggest that plasma preincubation of explanted pituitaries increases PRL cell sensitivity to TRH, perhaps by enzymatic inactivation of endogenous TRH bound to cellular membrane receptors.     

Application of microbore HPLC in combination with tandem MS for the quantification of rosuvastatin in human plasma

The potential of microbore high-performance liquid chromatography (HPLC) in combination with tandem mass spectrometry (MS/MS) for the sensitive detection of rosuvastatin (Crestor) in human plasma was investigated. Three microbore HPLC columns with internal diameters (i.d.) of 0.5, 1.0 and 2.0 mm were evaluated for column efficiency and mass sensitivity, and compared to a conventional 4.6 mm i.d. column. The 2.0 and 1.0 mm i.d. columns performed very well while the 0.5 mm i.d. column was slightly less efficient, this is probably due to a lower packing density. Good results with respect to gains in mass sensitivity compared to the conventional analytical column were achieved with the 2.0 and 1.0 mm columns. Thus, the 2.0 mm i.d. column had an improved signal-to-noise (S/N) ratio of 16 whilst the 1.0 mm i.d. column had an improved S/N ratio of greater than 70. Experiments with the 1.0 mm i.d. HPLC column were performed to determine the robustness of the microbore method for human plasma extracts after sample preparation using solid-phase extraction (SPE). A number of problems were encountered with extracts including high backgrounds, the blocking of the column and a rapid deterioration in column performance. The blocking of the column by particulates was solved by off-line filtration of the sample extracts. Peak tailing of the analytes and high background, both of which were due to endogenous interferences in the extracts, were eliminated using gradient elution. Using these approaches over 500 injections of plasma extracts were achieved without significant deterioration in assay performance. Quantities of rosuvastatin of 0.3 pg on-column could be detected and cross-validation experiments demonstrated that the conventional and the microbore HPLC-MS/MS methods provided similar information on the concentration of rosuvastatin but with greatly reduced sample consumption using the microbore method.     

Insight into role of selection in the evolution of polyglutamine tracts in humans

Glutamine tandem repeats are common in eukaryotic proteins. Although some studies have proposed that replication slippage plays an important role in shaping these repeats, the role of natural selection in glutamine tandem repeat evolution is somewhat unclear. In this study, we identified all of the glutamine tandem repeats containing four or more glutamines in human proteins and then estimated the nonsynonymous (d(N)) and synonymous (d(S)) substitution rates for the regions flanking the glutamine tandem repeats and the proteins containing them. The results indicated that most of the proteins containing polyglutamine (polyQ) tracts of four or more glutamines have undergone purifying selection, and that the purifying selection for the regions flanking the repeats is weaker. Additionally, we observed that the conserved repeats were under stronger selection constraints than the nonconserved repeats. Interestingly, we found that there was a higher level of purifying selection for the regions flanking the polyQ tracts encoded by pure CAG codons compared with those encoded by mixed codons. Based on our findings, we propose that selection has played a more important role than was previously speculated in constraining the expansion of polyQ tracts encoded by pure codons.