[Trace nutrients in total enteral nutrition: the basal status and longitudinal course]. / Oligonutrienti in nutrizione enterale totale: stato basale e andamento longitudinale.

INTRODUCTION: Previous studies demonstrated deficiencies of selenium and other micronutrients in patients receiving total enteral nutrition (TEN). The content and bioavailability of trace elements in enteral formulas can be suboptimal. MATERIAL AND METHODS: Basal blood levels of some trace elements (copper, iron, selenium, zinc) and vitamins (B12, folic acid) were determined in twenty patients at the beginning of TEN. Vitamin E was measured in 7 patients. Primary diagnosis was cancer (no. = 13) and organic brain syndromes (no. = 7). Commercially available polymeric and oligomeric enteral formulas were used, containing respectively, as a percent of RDA in 1500 kcal, 65-39% of copper, 180-135% of iron, 80-100% of zinc. Selenium was not indicated; determinations in our laboratory gave a content of 78-63% of the minimum recommended intake. Blood levels of copper and zinc (no. = 6), selenium (no. = 5), iron, transferrin and ferritin (no. = 13) were measured after two months of TEN (mean intake of 30 +/- 3 kcal/kg/day). Copper, selenium and zinc were measured with atomic absorption; iron with the complessometric method: vitamin B12 and folic acid with RIA; vitamin E with HPLC. RESULTS: Mean values, expressed as mean +/- SD (range) were: copper: 129 +/- 23 (82-300) micrograms/dl; iron: 37 +/- 18 (16-89) mg/dl; selenium: 53 +/- 20 (22-93) micrograms/dl; zinc: 85 +/- 34 (44-185) micrograms/dl; vitamin B12: 632 +/- 450 (140-1575) pg/ml); vitamin E: 5.4 +/- 1.5 (3.3-7.8) mg/dl; folic acid: 11 +/- 8 (2-20) ng/ml. Values below the lower normal limit were found in 100% (vitamin E), 89% (selenium), 60% (iron), 35% (zinc), 24% (vitamin B12) and 14% (folic acid) of the patients studied. Copper was higher than the upper normal limit in 31% of cases; no data below normal range was found. Mean blood levels of depleted subjects were at the 28%, 43%, 54% and 63% of the mean normal value respectively for iron, selenium, vitamin E and zinc. Blood iron (p < 0.05) and selenium (p < 0.001) were significantly lower in more malnourished patients (weight loss > 20% vs < 20% on usual body weight). After two months of TEN, a reduction of 33% of mean blood selenium was observed in 4 of 5 patients studied. Blood copper and zinc remained stable in 6 subjects with initial normal or higher than normal values. Blood iron increased nonsignificantly, ferritin remained stable, transferrin increased significantly (p < 0.05). No clinical deficiency syndromes were observed. CONCLUSIONS: A careful monitoring of micronutrients during TEN is recommended. Selenium content of enteral formulas, unless supplemented by the producers, seems to be insufficient to maintain the initial blood level in two months of TEN.

[Evaluation of blood methyl-mercury using HPLC in dentists and their assistants]. / Valutazione del metil-mercurio ematico mediante HPLC negli odontostomatologi e loro assistenti.

HPLC was used to measure blood levels of methyl mercury in dentists and their assistants.

Micro-scale liquid chromatographic method for the determination of bamifylline and its major metabolite in human plasma.

A sensitive micro-scale method based on isocratic elution reversed-phase ion-pair chromatography for the determination of bamifylline and its major metabolite (AC 119) in human plasma is described. The method is based on a liquid-liquid extraction clean-up followed by analysis on an LC-Packings Fusica (Delta Pak, RP-18, 5 microns, 300 A) column (15 cm x 330 microns. I.D.) with 0.03 M heptanesulphonate (pH 3.5)-acetonitrile (7:3, v/v) as the mobile phase. Data with respect to recovery, reproducibility and limits of detection are reported and discussed.

Micro-liquid chromatography method for the determination of ciclopiroxolamine after pre-column derivatization in topical formulations.

Ciclopiroxolamine is a broad-spectrum antimycotic drug. Neither the free acid (ciclopirox) nor its salt with ethanolamine (ciclopiroxolamine) can directly be quantified by liquid chromatography (LC) on both normal and reversed phases. This is due to the chelating function of the N-hydroxypyridone group that interacts strongly with stationary phases. Derivatization by alkylation forms a 1-alkyloxypirydone with regular chromatographic behaviour. A micro-LC method based on an isocratic elution reversed-phase system for quantification of ciclopiroxolamine in topical formulations is described. Chromatography was carried out using an LC Packings fused-silica capillary column (15 cm x 330 microns I.D.; Delta Pak, RP-18, 5 microns, 300 A) coupled to a Kontron 433 UV capillary detector. Data with respect to the derivatization reaction, recovery, reproducibility and limits of detection of the proposed method are reported and discussed.

Use of porous pyrolytic carbon for analytical and microscale high-performance liquid chromatographic bioseparations.

Porous carbonaceous adsorbent was prepared by carbonization of saccharose in silica gel pores followed by leeching out of the silica matrix. The product of pyrolysis was then deactivated by hydrogenation. The resulting adsorbent shows intermediate sorption properties between those of the highly polar pyrolytic glassy carbon and the hydrophobic graphitized carbon. The microparticulate mesoporous carbon was examined for its use in capillary HPLC separations. The separation of selected stereoisomers in a 320 microm I.D. capillary column packed with the porous carbon particles is described and discussed. Additionally, the porous carbon filled with dextran gel was tested as a material for direct HPLC analysis of drugs in human serum.

Lung morphology in experimental acute paraquat poisoning. SEM observations.

The authors describe the SEM ultrastructural aspects of rat lungs following acute paraquat poisoning. The results obtained confirmed previous TEM observations and suggest an early inhibition of secretory activity in type II alveolar cells. This morphological aspect can be related to the generally known early development of respiratory difficulties following acute paraquat poisoning. The technique employed allows a precise study of alveolar reepithelization in further stages of poisoning. These last observations agree with the hypothesis of reepithelization by type II alveolar cells.

HPLC determination of caffeine and theophylline in Paullinia cupana Kunth (guarana) and Cola spp. samples.

A reversed-phase high-performance liquid-chromatographic method for the determination of caffeine and theophylline in commercial guarana samples (drug obtained from the seeds of Paulinia cupana Kunth, Sapindaceae of the Amazon Region) and in Cola spp. samples is described and discussed. The methodology developed is simple and rapid with a minimum of samples preparation required. A comparison of five different techniques for the extraction of caffeine and theophylline is discussed. Furthermore the quantitative determination of caffeine and theophylline in five samples of Brasilian guarana, in two samples of dietetic products containing guarana, in two samples of Cola extract and in three of Cola seed powder are reported.

Neuropathy secondary to vitamin E deficiency in acquired intestinal malabsorption.

A patient with acquired intestinal malabsorption developed a motor-sensory polyneuropathy with a recurrent remittent course, normal CSF and reduced motor and sensory conduction velocities. Nerve biopsy showed axonal changes. Serum DL-alpha-tocopherol was abnormally low. Six months supplementation with vitamin E was followed by normalization of DL-alpha-tocopherol serum levels and clinical and electrophysiological improvement.

Evaluation of 2-(2-thiophenecarboxy)benzoic acid and related active metabolites in biological samples.

This paper describes a quantitative assay of 2-(2-thiophenecarboxy)benzoic acid and its systemic metabolites, namely salicylic acid and thiophenecarboxylic acid, by high-performance liquid chromatography with ultraviolet detection at 254 nm. Analytes were extracted from acidified samples with tert.-butylmethyl ether and separated with an RP-18 column (150 mm x 3 mm I.D., 5 microns particle size) with a mixture of 0.01 M potassium phosphate and methanol (70:30, v/v) at pH 3.1. The method proved to have the validation required for pharmacokinetic investigations in animals and humans.

Simultaneous measurement of L-dopa, its metabolites and carbidopa in plasma of parkinsonian patients by improved sample pretreatment and high-performance liquid chromatographic determination.

A procedure is described for the determination of L-3,4-dihydroxyphenylalanine (L-DOPA), its metabolites and carbidopa (CD) in plasma of Parkinsonian patients by high-performance liquid chromatography with dual working-electrode coulometric electrochemical detection. An efficient sample preparation scheme is presented for the isolation of L-DOPA, its metabolites and the catecholamines from the same plasma aliquot. After a simple deproteinization with methanol containing 2% of 0.5 M perchloric acid and evaporation of the solvent, L-DOPA, its metabolites and CD were separated with a 5-micron Nucleosil C18 column. Catecholamines were extracted from the supernatant of the deproteinized plasma by ion exchange on small columns and adsorption on alumina. Recoveries were close to 100% for L-DOPA, its metabolites and CD and 70% for catecholamines. The use of the same mobile phase for the concurrent assay of L-DOPA, its metabolites and catecholamines considerably increased the throughput of samples in the chromatographic system. The dual-electrode coulometric detector afforded peak identification by comparing current ratios. Monitoring of data from patients under L-DOPA therapy is reported.

Lipid peroxidation and irreversible cell damage: synergism between carbon tetrachloride and 1,2-dibromoethane in isolated rat hepatocytes.

The combination of 1,2-dibromoethane (DBE) with carbon tetrachloride (CCl4) in the isolated rat hepatocyte model produces a significant potentiation of both lipid peroxidation and plasma membrane damage induced by the latter compound. The increase in malondialdehyde production precedes the hepatocyte damage, evaluated in terms both of lactate dehydrogenase leakage and trypan blue exclusion. When hepatocytes are isolated from vitamin E pretreated rats, both the prooxidant and the cytotoxic effects of CCl4 are prevented. Also the synergism between CCl4 and DBE on lipid peroxidation disappears completely while that on cell damage is strongly reduced. The increased lipid peroxidation appears to be one of the mechanisms of the observed synergism between CCl4 and DBE on hepatocyte damage. Regarding the antioxidant status of the hepatocyte challenged with CCl4 and DBE, an early and significant consumption of vitamin E is observed only in the presence of the mixture of these xenobiotics. Total nonprotein thiol content is not significantly modified by CCl4 poisoning while DBE, alone and in association with CCl4, markedly decreases it. Vitamin E supplementation does not prevent but moderately delays total nonprotein thiol depletion due to DBE or to the mixture. Finally, glutathione transferase activity is significantly reduced by CCl4 treatment and not by DBE, and vitamin E supplementation totally prevents such inhibition. The increased prooxidant effect of CCl4 plus DBE compared to CCl4 alone seems related to the shift in DBE metabolism consequent to the CCl4-dependent inactivation of glutathione transferase.

Vitamin E supplementation in preeclampsia.

An oxidant/antioxidant imbalance has been suggested among the pathogenetic factors involved in preeclampsia. As vitamin E is one of the most important antioxidant body components, a nonrandomized controlled trial was undertaken in 36 preeclamptic patients in order to evaluate the effect of vitamin E supplementation (100-300 mg/day per os) on fetal and maternal outcome. Fetal mortality was similar in 14 patients treated with conventional therapy plus oral vitamin E supplementation (35%) and in 22 patients treated with conventional therapy only (36%). Furthermore, in both groups of patients proteinuria increased, and increased dosages of antihypertensive drugs were called for in order to control blood pressure. We conclude that, with these dosages and in case of an already established disease, vitamin E does not improve fetal outcome in severe preeclampsia. Furthermore, it does not show favorable effects on maternal hypertension and proteinuria.