The effect of roasting on boron isotope ratio in coffee beans: Implications for provenance studies of roasted coffee.

We determined δ11B values of green and roasted coffee beans from 20 locations worldwide and conducted laboratory experiments with the aim to investigate boron isotope fractionation during roasting. Authentic single origin roasted coffees were found to be isotopically lighter than their green bean counterparts, with an average difference of 1.5‰. This isotope fractionation can be explained as arising from partial dissociation of boric acid in capillary water of green beans, where 11B isotopes are preferentially partitioned into molecules of undissociated boric acid and are then volatised during roasting. However, boron isotope fractionation induced by roasting was significantly smaller than between-origin variations in δ11B values of green coffee beans that had the range of ∼54‰. This implies that δ11B isotopic composition of roasted coffee retains the geographical origin information within δ11B values of green beans when regional differences in boron isotopic composition of coffee are considered.

Evaluation of the Dade Behring Syva EMIT 2000 tacrolimus assay on the Bayer Advia 1650.

BACKGROUND: The Dade Behring Syva(R) EMIT (enzyme multiplied immunoassay technique) method for the measurement of tacrolimus in whole blood was evaluated against the Abbott IMx(R) microparticle enzyme immunoassay (MEIA) method. EMIT measures tacrolimus colorimetrically, whereas MEIA measures the analyte using fluorimetry. Both methods incorporate a protein precipitation step prior to measurement. METHOD: Whole blood specimens were treated by two types of precipitation technique followed by analysis for tacrolimus by either MEIA or EMIT on the Bayer Advia 1650. Linearity and precision were assessed and correlation analysis performed to evaluate the EMIT assay on the Bayer Advia 1650. RESULTS: The EMIT tacrolimus assay was linear over the concentration range 0.0-22.0 micro g/L; the limit of detection was 1.2 micro g/L. Correlation between the Syva EMIT and IMx tacrolimus assays was excellent (r = 0.959) and no significant bias existed between the two methods (mean difference, delta = 0.221 micro g/L). Calibration data for the EMIT assay was stable for a period of 24-48 h on the Advia between runs. CONCLUSION: The Syva EMIT assay for the measurement of tacrolimus in whole blood is suited for daily routine use on the Bayer Advia 1650.

The effect of a highly specific serotonin agonist on osmoregulated vasopressin secretion in healthy man.

OBJECTIVE: To explore a possible interaction of the serotonin neurotransmitter system and posterior pituitary function, we have looked at the effect of fluoxetine treatment on osmoregulated vasopressin secretion in normal men in two placebo controlled studies. DESIGN: In each study subjects took in random order for 7 days one capsule daily of placebo or 40 mg fluoxetine. On the 8th day subjects underwent assessment. Study 1 A hypo-osmotic stimulus of an oral water load of 20 ml/kg. Study 2 A hyperosmotic stimulus of intravenous infusion of 5% (855 mmol/l) saline at 0.06 ml/kg/min for 120 minutes. PATIENTS: Normal, healthy male volunteers. Study 1, 9; Study 2, 10. MEASUREMENTS: In both studies regular measures of plasma osmolality, sodium and vasopressin were made. In Study 1 urine osmolality was measured together with urine volume at set time points and an accumulative measure of percentage of water load excreted. Free water clearance was calculated. In Study 2 the relationship of plasma vasopressin to change in plasma osmolality was calculated for each subject by linear regression analysis. RESULTS: Serotonin agonism had no effect on baseline measurements in either study. Study 1 After 4 hours subjects excreted 95 and 99% of the water load after placebo and fluoxetine respectively (P = 0.407). There was no effect of fluoxetine compared to placebo on the pattern or extent of change of plasma osmolality (nadir 285.9 +/- 1.4 mosm/kg placebo, 283.1 +/- 1.1 mosm/kg fluoxetine, P = 0.145) or free water clearance or maximum urine dilution after oral water loading. Plasma vasopressin suppressed to a minimum concentration after both treatments in response to hypo-osmolality 0.5 +/- 0.1 pmol/l (placebo), 0.3 +/- 0.01 pmol/l (fluoxetine), P = 0.195. Study 2 Fluoxetine had no significant effect on the sensitivity of vasopressin release to change in plasma osmolality (0.33 +/- 0.06 pmol/l per mosm/kg placebo, 0.36 +/- 0.06 pmol/l per mosm/kg fluoxetine, P = 0.347). Nor was there a significant effect on the theoretical osmotic threshold for release of vasopressin (287.0 +/- 1.21 mosm/kg placebo, 286.9 +/- 1.09 mosm/kg fluoxetine, P = 0.700). CONCLUSION: We have found no evidence of a physiologically relevant effect of serotonin agonism on osmoregulated vasopressin release, or on the ability of normal man to excrete a water load. The possible reasons for this contrast to animal work are discussed.

A new sensitive radioimmunoassay for plasma arginine vasopressin.

A new extremely sensitive radioimmunoassay to measure plasma AVP has been developed. Antiserum to AVP of high affinity (Keq = 1.1 X 10(12) 1/mol), raised in rabbits, showed little cross-reaction with related analogues (LVP less than 0.03%, AVT, DDAVP, OXT less than 0.01). The specific activity of 125I-AVP (chloramine T method) was 1400-1750 Ci/mmol. The limit of detection of plasma AVP, after extraction of 2 ml plasma with Florisil, was 0.3 pmol/1. Coefficient of variations of plasma control (2 pmo1/1) were 9.7% (intraassay) and 15.3% (inter-assay), n = 15. Osmotic stimulation by hypertonic saline infusion caused a linear response in plasma AVP in normal subjects, but plasma AVP remained undetectable in patients with cranial diabetes insipidus. Suppression of AVP secretion by a standard oral water load and by alcohol and fluid in volunteers produced low or undetectable values of plasma AVP. In a patient with the syndrome of inappropriate antidiuresis, plasma AVP concentration was grossly elevated.

Effect of plasma interference on different vasopressin antisera.

The effect of plasma interference upon 2 AVP antisera both of high affinity and specificity, was investigated. Chromatography of plasma from a normal subject on Sephadex G-25 gave 3 peaks of AVP-like material with antibody A eluting in the void volume, salt volume and in the AVP volume; the quantity of AVP-like material detected in the void volume was 95% less with antibody B. Similar elution profiles were observed in a patient with cranial diabetes insipidus but the third peak was absent. AVP-like material in the first 2 peaks was probably due to interference in the radioimmunoassay. Extraction of plasma by Florisil reduced the first 2 peaks (antibody A) and eliminated the void volume peak (antibody B). Plasma interference affected the absolute values of plasma AVP concentrations of osmotically-stimulated normal and diabetic subjects. AVP antisera displaying least plasma interference are recommended for AVP radioimmunoassay.

Carbimazole and the autoimmune response in Graves' disease.

Microsomal antibodies and antibodies directed toward the receptor for thyroid-stimulating hormone (TSH) decreased in parallel while patients with Graves' disease were taking carbimazole, whereas no significant changes were observed during treatment with placebo or propranolol. The changes in autoantibody levels during carbimazole treatment were independent of changes in serum thyroxine and could have been due to a direct effect of the drug on autoantibody synthesis. Evidence for this suggestion was provided when low doses of methimazole (the active metabolite of carbimazole) were found to inhibit thyroid-autoantibody production in cultured lymphocytes. Since thyroid lymphocytes are probably a major site of thyroid-antibody synthesis in Graves' disease and methimazole is concentrated in the thyroid during treatment, a local action of the drug on antibody production seems likely. This possibility could be important in the use of carbimazole to control hyperthyroidism.

Mechanical dilatation of the cervix during labour.

An instrument designed to produce vibrations to the cervix was assessed as a method of shortening the active phase of labour in 138 patients with abnormal labour. Results showed that it shortened labour in multiparous but not in nulliparous women. The cervilator's obvious benefit in certain patients and lack of apparent complications suggest that it can be a valuable addition to labour ward equipment. Further work is required to establish in which patients the instrument is likely to have the greatest value.