Biomedical subjects

Ricardo Melo

Publications and source records attributed to Ricardo Melo.

3 recordsLinked to original sources

PubMed2005

Partial elucidation of Trichogramma putative sex pheromone at trace levels by solid-phase microextraction and gas chromatography-mass spectrometry studies.

Virgin females of the minute parasitoid wasp Trichogramma turkestanica produce about 2 pg/h of two putative sex pheromonal compounds. These compounds could be successfully sampled during 20-50 h with SPME from 1.8 mL vials, containing 50-110 wasps and analysed by GC-MS. Accurate mass measurements at the 1 ng scale were possible with an internal standard of sulphur. One compound with MW 236 was identified as a C17H32 hydrocarbon while the other compound was the corresponding allylic alcohol with composition C17H32O. The alcohol could be silylated on-fibre and its mass spectrum suggested the presence of a conjugated 2,4-diene moiety. A miniaturised solvent extraction system for SPME needles, using 5 microL of acetone in a microtube was developed. After reaction of the extracted volatiles with the dienophile 4-methyl-1,2,4-triazoline-3,5-dione (MTAD), GC-MS of the MTAD adducts confirmed the presence of a diene. Interpretation of the combined mass spectral data, in combination with retention indexes of both compounds on non-polar and polar columns, suggested 2,6,8,12-tetramethyltrideca-2,4-diene and 2,6,8,12-tetramethyltrideca-2,4-dien-1-ol as most probable structures. These compounds have not been described previously. Biogenetically, they are most likely polyketides made up of a C4 starter unit that has been elongated with C2 and C3 units. Further biological and synthetic studies are necessary to prove their role as sex pheromone, confirm the proposed structures and determine the correct stereochemistry of the double bonds and the methyl groups.

Animals↗

PubMed2004

Effects of hypertonic saline-dextran solution in cardiac valve surgery with cardiopulmonary bypass.

BACKGROUND: Hypertonic saline-dextran (HSD) solution may be beneficial in patients undergoing coronary artery surgery with cardiopulmonary bypass. Valvular dysfunction is associated with high pulmonary wedge pressure, pulmonary hypertension, and ventricular dysfunction. Fluid overload or transient left ventricular failure may occur with HSD infusion in such patients. This study evaluates the cardiorespiratory effects and tolerance of HSD solution infusion in patients undergoing cardiac valve surgery. METHODS: This prospective, randomized, double-blind study compared clinical, laboratory, hemodynamic, and respiratory measurements, and fluid balance in 50 patients over a 48-hour period after cardiopulmonary bypass for cardiac valve surgery. Twenty-five patients received 4 mL/kg of HSD during 20 minutes before cardiopulmonary bypass (HSD group). The control group received the same volume of Ringer's solution (Ringer group). RESULTS: Hospital mortality was zero. The HSD patients had a near zero fluid balance (6.5 +/- 13.5 mL/Kg/48 hours), and the control patients had a positive balance (91.0 +/- 33.7 mL/Kg/48 hours). Hemoglobin was similar in both groups, but more blood transfusions were necessary in the Ringer group (1.21 +/- 1.28 vs 0.48 +/- 0.59 units per patients). The HSD solution induced a higher cardiac index and left ventricular systolic work index postoperatively, and a lower systemic vascular resistance index until 6, 24, and 48 hours. Right ventricular systolic work index increased and pulmonary vascular resistance index decreased after HSD infusion. A better Pao(2)/Fio(2) relation was observed at 1 and 6 hours postoperatively in the HSD group and was associated with a shorter extubation time (432.0 +/- 123.6 vs 520.8 +/- 130.2 minutes). Increased oxygen delivery index occurred in the HSD group. The HSD infusion was well tolerated as none of the patients experienced fluid overload or had left ventricular failure develop. No other complication attributable to the use of HSD solution was observed. CONCLUSIONS: The HSD solution infusion in patients during cardiac valve surgery with cardiopulmonary bypass was well tolerated. Hemodynamic and respiratory functions improved and fluid balance was near zero during the first 48 hours as compared with a large positive balance in the control group. We conclude that HSD infusion is advantageous for patients undergoing cardiac valve surgery.

Adult↗

PubMedDate not supplied

[Pleurodesis].

Pleurodesis is a way of inducting an inflammatory process in the pleural surface in order to create the closure of the pleural space. The exact mechanism isn't completely understood and there is still a great deal of controversy concerning pleurodesis. Pleurodesis can be achieved by introduction of a sclerosant agent trough a chest tube into the pleural space, by medical thoracoscopy, by surgical thoracoscopy or by thoracotomy. The principal sclerosant agents are talc and tetracycline. The indications for pleurodesis are malignant recurrent pleural effusion, primary recurrent pneumothorax, secondary pneumothorax and benign pleural effusion resistant to medical treatment. There are, although, some contraindications to performing it. Serious complications of pleurodesis are rare and depend on the technique and agent used. The method of choice for pleurodesis is related to the experience and technical facilities available. The author presents a review about pleurodesis.

Humans↗