1,720,997 research outputs found
Fattori di conversione delle unità di misura convenzionali in Unità Internazionali (SI)
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Liquid chromatography with pre-column dansyl derivatisation and fluorimetric detection applied to the assay of morphine in biological samples
No full textA simple method employing pre-column dansylation and liquid chromatography is proposed for a very sensitive and specific assay of morphine in biological samples. Nalorphine is used as an internal standard. The detection limit is 0.2 picomol of injected morphine. In the assay of human sera spiked with 150 nmol/l, the intra- and inter-assay coefficients of variation were 3.7% (n = 10) and 4.5% (n = 10), respectively. No interferences were observed from more than 70 opiate and non-opiate drugs. Urine, plasma and total blood were assayed, using different extraction methods, with negligible interference from coextractives
A direct injection high-performance liquid chromatographic method with electrochemical detection for the determination of ethanol and methanol in plasma using an alcohol oxidase reactor
No full textA highly sensitive reversed-phase high-performance liquid chromatographic assay for ethanol and methanol in plasma, using a post-column enzymic reactor with electrochemical detection, has been developed. The alcohols, separated on the column, were converted by immobilized alcohol oxidase into their respective aldehydes with formation of stoichiometric amounts of hydrogen peroxide, detected via oxidation at a platinum electrode. As the chromatographic column, two glass cartridges (150 mm x 3 mm I.D.) in series, packed with 10 microns HEMA-S 1000 packing, were used. Alcohol oxidase from Candida boidinii was immobilized onto HEMA-BIO 1000 VS-L (10 microns), packed in a 30 mm x 3 mm I.D. glass cartridge. The reaction product, hydrogen peroxide, was detected with an amperometric detector with a platinum electrode, operated at +500 mV vs. an Ag/AgCl reference electrode. A 20-microliters volume of ten-fold diluted plasma was injected without any pre-treatment. Under the described conditions, methanol and ethanol were well resolved from each other and from the "front" of the chromatogram. The limit of detection was ca. 2.5 nmol for ethanol and 0.6 nmol for methanol in plasma, at a signal-to-noise ratio of 3. Excellent linearity was observed for ethanol, in the range 0.125-4 micrograms injected (r = 0.9999). In contrast, the response for methanol was markedly non-linear above 500 micrograms injected, presumably owing to progressive saturation of the reactor. The precision and accuracy of the assay were satisfactory, as was the reactor life (one month)
Manuale per valutazione e inquadramento di patologie surrenaliche e ipertensione arteriosa endocrina
No full textDetection of morphine in the hair of opiate addicts with the Abbott TDx: a note of caution [letter]
No full textNon-extraction HPLC method for simultaneous measurement of dyphylline and doxofylline in serum
No full textA direct injection HPLC method for the simultaneous measurement of dyphylline and doxofylline in serum is reported. Chromatography is carried out with a "Pinkerton" internal surface reversed-phase column and phosphate buffer (0.1 mol/L, pH 6.8) as mobile phase. Absorbance at 275 nm is monitored. Only 10 microL of serum is required to detect less than 1 mg of each drug per liter in biological samples. The standard curve for the method is linear over the range 6-100 mg/L, and precision is acceptable for both drugs, with CVs of 2% and 1.5% for respective concentrations of 6.2 and 25 mg/L. None of the 76 drugs tested for interference affected the measurement of either drug. Four samples can be injected per hour. This method provides a fast, accurate way to monitor two interesting therapeutic agents used in chronic obstructive airway diseases
High-performance liquid chromatographic determination of morphine in biological samples: an overview of separation methods and detection techniques
No full textHigh-performance liquid chromatogrpahy with electrochemical detection at present suits most of the needs of toxicologists for the determination of morphine and some related compounds in biological samples, although fluorescence detection is still a useful alternative. Chemiluminescence detection may be promising, but needs further optimization of its coupling with HPLC to give the best performances. Morphine detection by absorbance spectrophotometry does not seem to allow the degree of sensitivity and selectivity from matrix interferences that is required in most instances. However, this approach is useful when morphine congeners undetectable by alternative means (i.e., heroin and morphine-3-glucuronide) are to be determined or when a general toxicological screening is required
Altered thyroid in dialysed uremic patients
No full textThyroid abnormalities were studied in 40 uremic patients half of whom were receiving hemodialysis and half peritoneal dialysis. The following parameters were examined in all patients: total and free thyroxinemia, free and total triiodothyroninemia, basal thyreotropinemia and levels 20 mins after releasing hormone (TRH) stimulation, reverse T3, thyroglobulinemia, antithyroglobulin , antimicrosomial and antithyroperoxidase antibodies; a thyroid echography was also performed. Numerous alterations were found in thyroid parameters, with a greater frequency in hemodialysed patients (65%) than those undergoing peritoneal dialysis (52.5%). Among the parameters examined it is worth noting that total thyroxinemia was significantly reduced compared to controls, and FT3 was very significantly reduced. Among those patients undergoing peritoneal dialysis thyreotropinemia was increased in 6 cases (15%), whereas among hemodialysed patients it was reduced in 2 cases (5%). Ten patients (25%) in all appeared to be free of thyroid alterations and 30 (75%) showed one or more alteration of the parameters examined. Of the latter, 1 case of toxic multinodular goiter, 1 case of Plummer's adenoma in a pretoxic phase, 1 case of hypothyroidism, 15 cases of "sick euthyroid of syndrome", 3 cases with high antibody levels and 2 cases of single node goitre were diagnosed. The study confirmed the high incidence of thyroid alterations in uremic patients and, surprisingly, allowed the authors to diagnose a case of toxic multinodular goitre and a case of Plummer's adenoma at a pretoxic phase. The authors discuss the rarity of thyroid hyperfunction in uremia and suggest the need to consider patients with chronic renal insufficiency as being at risk of hypo-, normo- and hyperfunctioning thyreopathy, and to use a routine thyreotropinemia assay in all uremic patients
Calcitonin serum levels in heroin addicts: effects of methadone and clonidine detoxication treatments
No full textCalcitonin (CT), a 32-aminoacid peptide, is secreted by the parafollicular 'C' cells of the thyroid which derive from the ultimobranchial body and, ultimately, from the neural crest. In man, the main role of this hormone is to protect the skeleton during periods of physiological stress, such as growth, pregnancy and lactation by reducing calcium loss [1]. Nevertheless, some recent data, such as the finding of immunoreactive CT-like material (iCT) in the central nervous system [2] and in the cerebrospinal fluid and the demonstration of its analgesic action in rabbits [4] and in man [5] indicate a relationship between CT and the neuroendocrine system. The purpose of the present study is to evaluate the levels of CT in a group of addicts to heroin both before and during detoxication treatment with methadone or a non-opioid drug like clonidine
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