Biomedical subjects

M T Gomes

Publications and source records attributed to M T Gomes.

6 recordsLinked to original sources

PubMed2003

A mitogenic protein fraction in latex from Carica candamarcensis.

Latex from Caricaceae contains a number of proteins believed to be part of a defense mechanism that protects these plants from wounding. Prior evidence suggests that some components in Carica papaya improve healing of ulcerous wounds in mammals. This study shows the chromatographic isolation of a protein fraction from C. candamarcensis that stimulates cell proliferation of mammalian cells by measuring MTT reduction and thymidine incorporation. The effect appears to be cell specific as L929, MDA-MB231 and BHK-21 cells are stimulated while no effect is seen on CHO cells. The maximal stimulatory effect reaches 2.2-fold 72 h after addition of the active fraction to L929, 1.8-fold in MDA-MB231 cells and 1.6-fold in BHK cells. Proteolytic inactivation of the active fraction suggests that a protein is responsible for the proliferative activity and its size is estimated between 10 and 25 kDa. A potential candidate for this function is a 23 kDa protein found in the fraction that reacts with human EGF antibody.

Animals↗

PubMed2001

Alcohol determination using an acoustic wave sensor.

An acoustic wave methodology was developed to quantify alcohols in aqueous solutions. The frequency at minimum impedance of a bare quartz crystal in contact with ethanol solutions was found to be a suitable parameter to quantify ethanol. Ethanol in several Portuguese white wines was analyzed both by the proposed methodology and by the usual areometric method with no statistically significant differences (alpha = 0.05) in precision or accuracy of the results.

Electrochemistry↗

PubMed2001

Development of a sensor for calcium based on quartz crystal microbalance.

A new sensor for calcium based on a piezoelectric quartz crystal is presented. The selectivity depends on the ratio lipophilic salt/ionophore of the composition of the coating of the quartz crystal. A crystal coated with a THF solution of PVC (34.5% w/w), DOS (62.1% w/w) and 10,19-bis[(octadecylcarbamoyl) methoxyacetyl]-1,4,7,13,16-pentaoxa-10,19-diaza cycloheneicosane (3.4% w/w) and a salt/ionophore molar proportion of 60%, corresponding to a frequency decrease of the dry crystal of 6.0 kHz, showed a detection limit to calcium of 2.2 mg/L. Both a standard calcium chloride solution and a commercially balanced salt solution for tissue culture were analyzed subsequent to ion chromatographic separation. The results obtained with the sensor developed were compared with those obtained with a conductivity detector. Although the results from both detectors agreed for the standard solution, only the quartz crystal sensor was able to give reliable results for the tissue culture solution.

Calcium↗

PubMed2000

A gas chromatography-quartz crystal microbalance for speciation of sulfur compounds in landfill gas.

A new method, based on separation with gas chromatography and detection with a quartz crystal microbalance, was used for the quantification of ethane-1-thiol, propane-1-thiol, ethyl methyl sulfide, propane-2-thiol, butane-2-thiol and butane-1-thiol. The analytical error, the analysis time and the general analytical performance are identical for gas chromatography-mass spectrometry (GC-MS) and gas chromatography-quartz crystal microbalance (GC-QCM). However, the GC-QCM method constitutes a low cost alternative to GC-MS for monitoring individual sulfur compounds in landfill gas. It is an easily assembled apparatus made with an injection device, a furnace, a column, a crystal cell and a quartz crystal.

Air Pollutants↗

PubMed1999

A new method for monitoring the contamination of glycerol with diethylene glycol.

A quartz crystal microbalance has been used to check the purity of glycerol. The experimental procedure involves no derivatization or other preliminary step except determination of water content. The protocol consists of the direct reading of the frequency of a quartz crystal with one face in contact with an aqueous solution of the glycerol to be tested. The method is inexpensive, simple, rapid, and highly sensitive; diethylene glycol contamination at the 3.61% level could be detected.

Biosensing Techniques↗

PubMed1997

Optimisation of the experimental conditions of a new method, based on a quartz crystal microbalance, for the determination of cyanide.

A new method based on a quartz crystal microbalance was developed for the determination of cyanide. As the sensitivity depends on pH, temperature and nitrogen flow rate, a modified simplex was used to optimise these experimental parameters. Two different versions of the proposed method were optimised. For the first version a sensitivity increase of 1.5 was observed after 27 runs, whereas for the second version a sensitivity increase of 1.7 was observed after 12 runs.

Cyanides↗