On-line monitoring of chemical reactions by using bench-top nuclear magnetic resonance spectroscopy.

Real-time nuclear magnetic resonance (NMR) spectroscopy measurements carried out with a bench-top system installed next to the reactor inside the fume hood of the chemistry laboratory are presented. To test the system for on-line monitoring, a transfer hydrogenation reaction was studied by continuously pumping the reaction mixture from the reactor to the magnet and back in a closed loop. In addition to improving the time resolution provided by standard sampling methods, the use of such a flow setup eliminates the need for sample preparation. Owing to the progress in terms of field homogeneity and sensitivity now available with compact NMR spectrometers, small molecules dissolved at concentrations on the order of 1 mmol L(-1) can be characterized in single-scan measurements with 1 Hz resolution. Owing to the reduced field strength of compact low-field systems compared to that of conventional high-field magnets, the overlap in the spectrum of different NMR signals is a typical situation. The data processing required to obtain concentrations in the presence of signal overlap are discussed in detail, methods such as plain integration and line-fitting approaches are compared, and the accuracy of each method is determined. The kinetic rates measured for different catalytic concentrations show good agreement with those obtained with gas chromatography as a reference analytical method. Finally, as the measurements are performed under continuous flow conditions, the experimental setup and the flow parameters are optimized to maximize time resolution and signal-to-noise ratio.

Perirectal sepsis after rubber band ligation of haemorrhoids : a case report.

Rubber band ligation (Barron ligation, RBL) is a widely used method for the treatment of symptomatic -haemorrhoids. In general, it is considered as a safe, effective and easily performed way of treating second and third -degree haemorrhoids. Perineal and pelvic sepsis was already known to be a rare, but possible complication after stapled haemorrhoidopexy. However, there have been some reports of severe sepsis after rubber band ligation as well. We -present a patient who was treated twice for haemorrhoids with rubber band ligation and attended the emergency department 10 days later. He was diagnosed with perirectal sepsis and aggressive antibiotic treatment was the first attempt of treatment. Because of further deterioration under medical therapy, our patient required extensive surgery.

Prevalence and risk factors for gonococcal infection in Reunion Island.

OBJECTIVE: To determine the prevalence and risk factors for gonococcal infection, and the resistance profile of Neisseria gonorrhoeae (NG) in Reunion Island. PATIENTS AND METHODS: All patients who visited the four sexually transmitted infection (STI) clinics of Reunion Island between January 2017 and December 2018 were screened by multiplex polymerase chain reaction. Data on patient characteristics were collected using a self-administered questionnaire (reason for screening, marital status, risk-taking behaviors, place of birth, employment status, type of health care coverage, sexual orientation, number of sexual partners, occurrence of extra-marital relationships, history of STIs, and symptomatology. Precarity was defined as being unemployed and/or receiving universal health insurance). RESULTS: The prevalence of NG (n=4289) in the screened population was 2.8% (95% CI [2.3-3.3]). Minors were especially at-risk (4.4% (95% CI [2.6-7])) and especially girls (5.6% (95% CI [3.2-8.9])). The prevalence observed in the homosexual population was 4.0% [2.6-5.9]. Gonococcal infection was asymptomatic in 56 (69%) patients. For all infection sites, the main risk factors were male minors (P=0.019), individuals living in conditions of precarity (P=0.023), individuals co-infected with chlamydia (P<0.001) or syphilis (P<0.001), and individuals of foreign origin (P=0.006). No NG strain was resistant to ceftriaxone. Strains were resistant to penicillin G, ciprofloxacin, and azithromycin in 22% (20/91), 38% (35/91), and 1% (1/91) of cases, respectively. CONCLUSION: The prevalence of NG in patients visiting STI clinics in Reunion Island is particularly high among minors. Prevention programs targeting this population should be reinforced and screening should be facilitated in school settings.

Stability study of a nisin/natamycin blend by LC-MS.

Nisin and natamycin are natural preservatives used in a broad range of food products. In the present study, the stability of an aqueous nisin/natamycin blend (pH 4.0) for the beverage market was tested at room temperature (22 °C) under dark conditions by means of liquid chromatography. Both an HPLC-UV and a UPLC-MS method were developed to monitor the concentration of natamycin and nisin, respectively. After 6 months at room temperature (22 °C) under dark conditions, the nisin/natamycin blend (pH 4.0) still contained 85% of the original amount of nisin and 95% of natamycin. Even after 1 year, 50% of nisin and 90% of natamycin remained in the formulation. The resulting degradation products were studied by means of high resolution mass spectrometry. For both nisin and natamycin, degradation products originating from hydration (natamycin + H2O; nisin + H2O) and oxidation reactions (natamycin + O; nisin + O; nisin + 2O) were observed.

Enantioselective high-performance liquid chromatographic separation of N-methyloxycarbonyl unsaturated amino acids on macrocyclic glycopeptide stationary phases.

This paper describes the enantiomeric resolution of a series of unsaturated N-methyloxycarbonyl-alpha-H-alpha-amino acids (N-MOC-alpha-amino acids) on macrocyclic glycopeptide stationary phases by means of high-performance liquid chromatography (HPLC). Three types of glycopeptide phases, i.e. Chirobiotic T, V and R, were evaluated in both reversed-phase (RP) and polar ionic mode (PIM). The best results in terms of enantioselectivity and resolution were obtained on Chirobiotic R phase, with the PIM mobile phase giving the highest resolution per min. Investigation of the pH of the reversed-phase mobile phase in the pH range 4.1-5.9 showed little effect on enantioselectivity. The method was applied for monitoring the conversion and product enantiomeric excess of an enzymatic hydrolysis reaction using N-MOC-alpha-H-alpha-amino acid esters as substrate.

Prevention by aluminium phosphate of gastric lesions induced by ethanol in the rat: role of endogenous prostaglandins and sulfhydryls.

This study was designed to demonstrate the cytoprotective effect of an antacid containing aluminium phosphate (Phosphalugel) against ethanol-induced gastric injury in the rat and to determine whether this cytoprotective effect is mediated by endogenous prostaglandins and sulfhydryls. We have quantitatively evaluated gastric mucosal lesions using macroscopic and histological techniques one hour after ethanol administration. Two ml of aluminium phosphate given orally one hour before administration of 2 ml of 100% ethanol significantly (p less than 0.01) reduced the area of macroscopic lesions induced by ethanol (3.3 +/- 0.9%) when compared to distilled water (20 +/- 4.8%). The histological study showed that aluminium phosphate prevented deep tissue necrosis. However, it did not protect surface epithelial cells against ethanol injury. Pretreatment with indomethacin, 5 mg/kg sc one hour before aluminium phosphate, slightly but significantly (p less than 0.05) reduced the cytoprotective effect of aluminium phosphate. Macroscopic lesions occupied 4.3 +/- 0.94% and 1.88 +/- 0.41% of total mucosal area in indomethacin group and in vehicle group, respectively. On the other hand, the sulfhydryl blocker, N-ethyl-maleimide, 10 mg/kg sc, given one hour before aluminium phosphate, completely abolished the cytoprotective effect of aluminium phosphate (32.92 +/- 4.85% in N-ethyl-maleimide group versus 3.78 +/- 1.41% in vehicle group; p less than 0.01). These results show that aluminium phosphate has a cytoprotective effect against ethanol injury in the rat. This property appears to be mediated by both endogenous prostaglandins and sulfhydryls.

Characterization of serotonin receptors and lack of effect of antidepressant therapy on monoamine functions in various regions of the rabbit brain.

The effects of single and long-term administration of the antidepressants imipramine, desimipramine, amitriptyline, zimelidine and maprotiline were studied in the rabbit brain. Special attention was given to the brain serotonin (5-HT) receptors. Our results show that in different areas of the rabbit brain, the binding sites for 5-HT display pharmacological characteristics very similar to those of the 5-HT1 and 5-HT2 receptors described for the rat brain. No significant correlation could be shown between the distribution of either of the receptors and the distribution of serotonergic nerve terminals (as measured by the 5-HT content and the [3H]5-HT accumulation). Addition of antidepressants to rabbit brain slices, in vitro, caused an inhibition of the [3H]5-HT accumulation. The compounds only weakly inhibited the binding of [3H]5-HT and [3H]ketanserin as compared to the inhibition caused by serotonergic agonists and antagonists. The [3H]5-HT accumulation in brain slices was markedly reduced 2 h after a single i.p. injection of imipramine. After a two-week administration of the antidepressants, the specific binding of neither [3H]5-HT nor [3H]ketanserin was significantly altered. The simultaneous determination of monoamine metabolites and of dopamine-beta-hydroxylase in the cerebrospinal fluid of these treated rabbits did not reveal any significant difference from the control animals.

Determination of the enantiomers of 3-tert.-butylamino-1,2-propanediol by high-performance liquid chromatography coupled to evaporative light scattering detection.

A method for the separation and quantitation of the enantiomers of 3-tert.-butylamino-1,2-propanediol by high-performance liquid chromatography and evaporative light scattering detection has been developed. Separation of the enantiomers was performed in normal-phase liquid chromatography on a Chiralpak AS chiral stationary phase. The influence of the gas nature, gas pressure and temperature of the drift tube of the evaporative light scattering detector on the detection sensitivity was investigated. The method was validated in terms of linearity, limit of quantitation, accuracy and precision. The enantiomeric excess of (S)-3-tert.-butylamino-1,2-propanediol, used for the industrial synthesis of (S)-timolol, was measured from 0 to 94%.

High-performance liquid chromatographic determination of alpha-aminonitrile enantiomers after derivatization with o-phthalaldehyde and chiral thiols.

o-Phthalaldehyde in combination with chiral thiols is described as a chiral reagent for the resolution of the enantiomers of alpha-H-alpha-aminonitriles and alpha-alkyl-alpha-aminonitriles. Separation of the resulting diastereomers was carried out by reversed-phase chromatography and the derivatives were detected at UV 340 nm. The identity of the diastereomeric derivatives was confirmed by LC-MS. Among the chiral thiols tested, N-acetyl-D-penicillamine and beta-mercaptoisobutyric acid gave the best resolution for the alpha-aminonitriles studied. For quantitative enantiomeric excess determination, beta-mercaptoisobutyric acid was chosen as this thiol could be obtained in high enantiomeric purity from a commercial source. The rate of the reaction of various alpha-aminonitriles with o-phthalaldehyde and beta-mercaptoisobutyric acid was studied. The accuracy of the method was investigated by a comparison of theoretical and measured enantiomeric excess.

Evaluation of sample work-up methods and internal standards for the determination of 5-hydroxytryptamine and 5-hydroxyindoleacetic acid in brain by HPLC with electrochemical detection.

A high-performance liquid chromatographic method with electrochemical detection is described for the determination of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in brain. Results of studies on sample work-up methods and on the use of various internal standards are reported. The reproducibility of determination of 5-HT and 5-HIAA in two regions of rabbit brain has been evaluated.

Thermospray liquid chromatography/mass spectrometry study of diastereomeric isoindole derivatives of amino acids and amino acid amides.

A thermospray liquid chromatography/mass spectrometry (TSP-LC/MS) method is described for determination of the enantiomeric excess of alpha-amino acids and alpha-amino acid amides as their o-phthalaldehyde/N-acetyl-L-cysteine (OPA/NAC) derivatives. The source temperature is an important factor in optimizing the sensitivity of the TSP-LC/MS analysis, whereas the repeller voltage is of minor importance. On-column mass spectra were acquired for the OPA/NAC derivatives of several alpha-amino acids and alpha-amino acid amides. For the main fragment ions, mass spectra fragmentation pathways are proposed. The applicability of the method is demonstrated by means of the enantiomeric excess determination of valine in a sample from an enzymatic hydrolysis experiment. Using single ion monitoring, the detection limit of D-valine in the presence of excess L-valine is 10 pmol. The present TSP-LC/MS method is useful for validating the results obtained from LC/UV or LC/fluorescence methods for the enantiomeric excess determination of alpha-amino acids and alpha-amino acid amides.

The efficacy of estrus detection and fertility following synchronization with PGF2a or synchro - mate- B in Zebu cattle.

Two experiments were carried out to assess the efficacy of estrus detection and fertility in Zebu cattle after synchronization with prostaglandin F2a or a progestagen. The first experiment compared estrus detection rates and fertility following insemination in 42 cows previously synchronized with either 25 mg of PGF2a or with a 6 mg of Norgestomet implant plus 5 mg i.m. of estradiol valerate (SMB). Differences were observed in the percentage of cows detected in estrus (54 vs 95%, respectively, P < 0.05), but not in fertility at the first synchronized estrus (26 vs 15%), nor in the detection rate and fertility at the subsequent estrous period (38 v 47%). The second experiment evaluated the efficacy of estrus detection at different time intervals in 30 cows, comparing estrus synchronized with PGF2a with the subsequent estrous period. The observation periods were continuous, day and night, for 100 h both after PGF2a treatment and from Day 18 of the treatment cycle (Period 1). In addition, the animals were administered PGF2a again on Day 10 of the second cycle and observed continuously from 0600 to 1800 h, and from Day 18 of the treatment cycle (Period 2). Finally, the same treatment regimen was used except that the observation was between 0600 to 0700 h and 1800 to 1900 h (Period 3). No differences were obtained in the percentage of cows detected in estrus in the synchronized and nonsynchronized groups (average 75%); however, accuracy in the detection of estrus in Period 3 differed in the nonsynchronized and synchronized estrus groups by 40% (P < 0.05) compared with the other two, more intense observation periods.

Fertility trial in Zebu cattle after a natural or controlled estrus with prostaglandin F2 Alpha, comparing natural mating with artificial insemination.

With the object of comparing reproductive efficiency obtained by natural mating and by artificial insemination (AI), not only following a natural estrus but also after an induced estrus with PGF2Alpha in Zebu cattle in the tropics, 244 adult cows were divided into 4 groups. Group I (N = 69) and Group III (n = 62) were injected with 25 mg of PGF2Alpha when a functional CL was found on rectal examination. Group I was inseminated and group III was served by natural mating, both groups within five days after injection. Groups II (n = 57) and IV (n = 56) were left untreated, group II being AI and group IV ran with a fertile bull for 22 days. Estrus detection was carried out only in the injected groups (I and III) for 15 minutes every three hours between 0600 and 1800. All information was analyzed by linear trigonometric models. The onset of estrus occurred on average 68.7 h after injection in group I and 59.5 h in group III. However only 46.3% and 54.8% of animals were detected in estrus in group I and III respectively, the difference being significant (P < 0.10). Conception rates were 18.6%, 29.8%, 19.3% and 33.9% for groups I, II, III, and IV respectively. A significant difference (P < 0.10) existed between the injected groups and the untreated ones.

Comparative evaluation of four detectors in the high-performance liquid chromatographic analysis of chiral nonaromatic alcohols.

A comparative evaluation of ultraviolet, polarimetric, refractive index, and evaporative light-scattering detection coupled with high-performance liquid chromatography has been developed for the separation and quantitation of the enantiomers of chiral nonaromatic alcohols, some of which are intermediates in the synthesis of chiral drugs. (R,S)-3-tert-butylamino-1,2-propanediol; (R,S)-glycidol; and (R,S)-1-(4-morpholino)-2-octanol are selected as model compounds in order to compare the detection sensitivity and the linearity of the response with the four detectors. Separation of the enantiomers is performed using chiral stationary phases in normal-phase liquid chromatography. A one-day validation is achieved for (S)-3-tert-butylamino-1,2-propanediol with each detector, and limits of quantitation are determined for the three compounds. Advantages and limitations of the four detectors are discussed.

Uterine tube abnormalities in cattle.

A total of 250 reproductive tracts from nonpregnant cows were obtained from a slaughterhouse. Uterine tubes were tested for patency by infusing methylene blue solution, and gross lesions were recorded. Of the 500 uterine tubes, 24 were occluded (unilateral in 20 tracts and bilateral in 2 tracts), and 26 had gross lesions (unilateral in 16 tracts and bilateral in 5 tracts). Approximately one-half of the occluded tubes were not associated with gross lesions. Approximately one half of the tubes with gross lesions were patent.

Reproductive physiology in Zebu cattle. Unique reproductive aspects that affect their performance.

This article describes the reproductive physiology of Zebu cattle and specific strategies that, when used in concert with an understanding of the physiologic differences between Zebu and other cattle, can improve reproductive performance.

[Gastroprotective effect of an antacid coating agent in rats. Role of endogenous prostaglandins, capsaicin-sensitive afferents neurons and nitric oxide]. / Etude de l'effect gastroprotecteur d'un pansement antiacide chez le rat. Rôle des prostaglandines endogènes, des neurones afférents sensibles à la capsaïcine et du monoxyde d'azote.

UNLABELLED: The aims of this study were: a) to demonstrate the gastroprotective effect of the antacid and mucosal coating agent Gastralgine (aluminium hydroxide and glycinate, magnesium trisilicate and simeticone) against ethanol- and indomethacin-induced gastric injury in the rat; b) to investigate whether gastroprotection elicited by this agent involves stimulation of capsaicin sensitive afferent neurons and activation of the nitric oxide system. METHODS: Rats received intragastrically 2 mL of the antacid or distilled water followed 1 hr later by 2 mL of 100% ethanol ig or 30 mg of indomethacin sc. The surface of ethanol-induced lesions and the length of indomethacin-induced lesions were measured. The role of afferent neurons and endogenous nitric oxide in the prevention of ethanol-induced gastric damage was determined using respectively capsaicin and the inhibitor of nitric oxide biosynthesis, NG-nitro-L-arginine. RESULTS: The antacid and mucosal coating agent significantly reduced the area of macroscopic lesions induced by ethanol and the length of lesions induced by indomethacin. Both functional ablation of afferent nerves and inhibition of nitric oxide synthesis significantly increased ethanol-induced gastric injury but failed to reverse the gastroprotective effect of the antacid against 100% ethanol. CONCLUSIONS: The antacid and mucosal coating agent Gastralgine has a gastroprotective effect against ethanol- and indomethacin-induced injury in the rat. This property does not involve stimulation of capsaicin sensitive afferent neurons or synthesis of endogenous nitric oxide.