norma trejo - Academia.edu (original) (raw)

Papers by norma trejo

Research paper thumbnail of Characterization of nebulized buparvaquone nanosuspensions—effect of nebulization technology

Journal of Drug Targeting, 2005

The poorly soluble drug buparvaquone is proposed as an alternative treatment of Pneumocystis cari... more The poorly soluble drug buparvaquone is proposed as an alternative treatment of Pneumocystis carinii pneumonia (PCP) lung infections. Physically stable nanosuspensions were formulated in order to deliver the drug at the site of infection using nebulization. The aerosolization characteristics of two buparvaquone nanosuspensions were determined with commercial jet and ultrasonic nebulizer devices. Aerosol droplet size distribution was determined with laser diffractometry (LD). Nebulization of the nanosuspensions and dispersion media surfactant solutions produced aerosol droplets diameters in the range from 3 to 5 mm for Respi-jet Kendall, Pari Turbo Boy system and Multisonic nebulizers and particles around 9-10 mm with Omron U1. Fractions of the nanosuspensions from the nebulizer reservoir and of aerosol produced were collected to investigate changes in the size of the drug nanocrystals influenced by the nebulization technology. Comparisons were performed measuring the drug nanocrystals with photon correlation spectroscopy (PCS) and LD of the samples. Drug particle aggregates were detected in the fractions of aerosol collected from jet nebulizers. Nebulizer technology (jet vs. ultrasonic) showed influence on the stability of the drug particle size distribution of buparvaquone nanocrystals during the nebulization time evaluated.

Research paper thumbnail of Influence of previous bilateral partial tubal resection on symptoms, hormones, lipids, and bone density in postmenopausal women

Influence of previous bilateral partial tubal resection on symptoms, hormones, lipids, and bone density in postmenopausal women

Contraception, 1997

The late effect of bilateral partial tubal resection (BPTR) on symptoms, hormone and lipid levels... more The late effect of bilateral partial tubal resection (BPTR) on symptoms, hormone and lipid levels, and bone density in postmenopausal women was analyzed. Thirty-six postmenopausal women in whom BPTR was accomplished were studied; they were matched by age with a group without BPTR. They were subdivided according to time since BPTR into two groups: < or = 15 years > 15 years since the procedure. In both groups, the patients' general data were analyzed as well as the frequency of climacteric symptoms; serum levels of follicule-stimulating hormone (FSH), estradiol, total cholesterol, HDL-C, LDL-C, and triglycerides; and bone density in lumbar spine, femoral neck, Ward's triangle, and trochanter. The statistical analysis was done for the symptoms with chi-squared and for the rest of variables with Student's t-test. When comparing the groups, no differences were found in analyzed parameters; only hot flashes and sweating associated with hot flashes were frequently found in the BPTR group when the analysis was done in the group without any division. With the groups subdivided, hot flashes were found more frequently in the group for whom it had been more than 15 years since the BPTR procedure. The BPTR did not influence hormone and lipid levels or bone density.

Research paper thumbnail of REVIEW Biodiesel Fuel Production by Transesterification of Oils

Biodiesel (fatty acid methyl esters), which is derived from triglycerides by transesterification ... more Biodiesel (fatty acid methyl esters), which is derived from triglycerides by transesterification with methanol, has attracted considerable attention during the past decade as a renewable, biodegradable , and nontoxic fuel. Several processes for biodiesel fuel production have been developed, among which transesterification using alkali-catalysis gives high levels of conversion of triglycer-ides to their corresponding methyl esters in short reaction times. This process has therefore been widely utilized for biodiesel fuel production in a number of countries. Recently, enzymatic trans-esterification using lipase has become more attractive for biodiesel fuel production, since the glyc-erol produced as a by-product can easily be recovered and the purification of fatty methyl esters is simple to accomplish. The main hurdle to the commercialization of this system is the cost of lipase production. As a means of reducing the cost, the use of whole cell biocatalysts immobilized within biomass support particles is significantly advantageous since immobilization can be achieved spontaneously during batch cultivation, and in addition, no purification is necessary. The lipase production cost can be further lowered using genetic engineering technology, such as by developing lipases with high levels of expression and/or stability towards methanol. Hence, whole cell bio-catalysts appear to have great potential for industrial application.

Research paper thumbnail of Characterization of nebulized buparvaquone nanosuspensions—effect of nebulization technology

Journal of Drug Targeting, 2005

The poorly soluble drug buparvaquone is proposed as an alternative treatment of Pneumocystis cari... more The poorly soluble drug buparvaquone is proposed as an alternative treatment of Pneumocystis carinii pneumonia (PCP) lung infections. Physically stable nanosuspensions were formulated in order to deliver the drug at the site of infection using nebulization. The aerosolization characteristics of two buparvaquone nanosuspensions were determined with commercial jet and ultrasonic nebulizer devices. Aerosol droplet size distribution was determined with laser diffractometry (LD). Nebulization of the nanosuspensions and dispersion media surfactant solutions produced aerosol droplets diameters in the range from 3 to 5 mm for Respi-jet Kendall, Pari Turbo Boy system and Multisonic nebulizers and particles around 9-10 mm with Omron U1. Fractions of the nanosuspensions from the nebulizer reservoir and of aerosol produced were collected to investigate changes in the size of the drug nanocrystals influenced by the nebulization technology. Comparisons were performed measuring the drug nanocrystals with photon correlation spectroscopy (PCS) and LD of the samples. Drug particle aggregates were detected in the fractions of aerosol collected from jet nebulizers. Nebulizer technology (jet vs. ultrasonic) showed influence on the stability of the drug particle size distribution of buparvaquone nanocrystals during the nebulization time evaluated.

Research paper thumbnail of Influence of previous bilateral partial tubal resection on symptoms, hormones, lipids, and bone density in postmenopausal women

Influence of previous bilateral partial tubal resection on symptoms, hormones, lipids, and bone density in postmenopausal women

Contraception, 1997

The late effect of bilateral partial tubal resection (BPTR) on symptoms, hormone and lipid levels... more The late effect of bilateral partial tubal resection (BPTR) on symptoms, hormone and lipid levels, and bone density in postmenopausal women was analyzed. Thirty-six postmenopausal women in whom BPTR was accomplished were studied; they were matched by age with a group without BPTR. They were subdivided according to time since BPTR into two groups: < or = 15 years > 15 years since the procedure. In both groups, the patients' general data were analyzed as well as the frequency of climacteric symptoms; serum levels of follicule-stimulating hormone (FSH), estradiol, total cholesterol, HDL-C, LDL-C, and triglycerides; and bone density in lumbar spine, femoral neck, Ward's triangle, and trochanter. The statistical analysis was done for the symptoms with chi-squared and for the rest of variables with Student's t-test. When comparing the groups, no differences were found in analyzed parameters; only hot flashes and sweating associated with hot flashes were frequently found in the BPTR group when the analysis was done in the group without any division. With the groups subdivided, hot flashes were found more frequently in the group for whom it had been more than 15 years since the BPTR procedure. The BPTR did not influence hormone and lipid levels or bone density.

Research paper thumbnail of REVIEW Biodiesel Fuel Production by Transesterification of Oils

Biodiesel (fatty acid methyl esters), which is derived from triglycerides by transesterification ... more Biodiesel (fatty acid methyl esters), which is derived from triglycerides by transesterification with methanol, has attracted considerable attention during the past decade as a renewable, biodegradable , and nontoxic fuel. Several processes for biodiesel fuel production have been developed, among which transesterification using alkali-catalysis gives high levels of conversion of triglycer-ides to their corresponding methyl esters in short reaction times. This process has therefore been widely utilized for biodiesel fuel production in a number of countries. Recently, enzymatic trans-esterification using lipase has become more attractive for biodiesel fuel production, since the glyc-erol produced as a by-product can easily be recovered and the purification of fatty methyl esters is simple to accomplish. The main hurdle to the commercialization of this system is the cost of lipase production. As a means of reducing the cost, the use of whole cell biocatalysts immobilized within biomass support particles is significantly advantageous since immobilization can be achieved spontaneously during batch cultivation, and in addition, no purification is necessary. The lipase production cost can be further lowered using genetic engineering technology, such as by developing lipases with high levels of expression and/or stability towards methanol. Hence, whole cell bio-catalysts appear to have great potential for industrial application.