Biomedical subjects

A de Castro

Publications and source records attributed to A de Castro.

At least 19 recordsLinked to original sources

PubMed2006

Degradation kinetics of the antioxidant additive ascorbic acid in packed table olives during storage at different temperatures.

The kinetics of ascorbic acid (AA) loss during storage of packed table olives with two different levels of added AA was investigated. Three selected storage temperatures were assayed: 10 degrees C, ambient (20-24 degrees C), and 40 degrees C. The study was carried out in both pasteurized and unpasteurized product. The effect of pasteurization treatment alone on added AA was not significant. In the pasteurized product, in general AA degraded following a first-order kinetics. The activation energy calculated by using the Arrhenius model averaged 9 kcal/mol. For each storage temperature, the increase in initial AA concentration significantly decreased the AA degradation rate. In the unpasteurized product, AA was not detected after 20 days in samples stored at room temperature and AA degradation followed zero-order kinetics at 10 degrees C, whereas at 40 degrees C a second-order reaction showed the best fit. In both pasteurized and unpasteurized product, the low level of initial dehydroascorbic acid disappeared during storage. Furfural appeared to be formed during storage, mainly at 40 degrees C, following zero-order kinetics.

Ascorbic Acid↗

PubMed2005

Liquid chromatography-electrospray ionisation mass spectrometry for the determination of nine selected benzodiazepines in human plasma and oral fluid.

A new simple and rapid liquid chromatographic-mass spectrometric technique was designed for the determination of nine benzodiazepines in plasma and oral fluid. Benzodiazepines were extracted from alkalinised spiked and clinical plasma and oral fluid samples using a single step, liquid-liquid extraction procedure with diethyl ether. The chromatographic separation was performed with a Xterra RP18, 5 microm (150 x 2.1 mm i.d.) reversed-phase column using deuterated analogues of the analytes as internal standard. The recovery ranged from 70.3 to 86.9% for plasma and 63.9 to 77.2% for oral fluid. The limits of detection ranged from 0.5 to 1 ng/ml in plasma and 0.1 to 0.2 ng/ml for oral fluid. The method was validated for all the compounds, including linearity and the main precision parameters. The procedure, showed to be sensitive and specific, was applied to real plasma and oral fluid samples. The method is especially useful to analyse saliva samples from drivers undergoing roadside drug controls.

Benzodiazepines↗

PubMed2004

Development and validation of a method for the quantitation of Delta9tetrahydrocannabinol in oral fluid by liquid chromatography electrospray-mass-spectrometry.

Analysis of Delta(9)tetrahydrocannabinol (Delta(9)THC) and its metabolites in biological samples is of great relevance for forensic purposes. In the case of oral fluid (OF), the analysis should determine Delta(9)THC, whereas in urine, it detects the inactive metabolite tetrahydrocannabinol carboxylic acid (THC-COOH). Most laboratories analyze Delta(9)THC in such samples using GC-MS methods, but these procedures are time-consuming and involve unavoidable previous extraction and derivatization. No data is yet available on the application of liquid chromatography-mass-spectrometry to detect Delta(9)THC in oral fluid. We report a validation method in which the Delta(9)THC is isolated from oral fluid by a simple liquid-liquid extraction with hexane and subsequently analyzed by liquid chromatography-mass-spectrometry. The method here reported for the determination of Delta(9)THC in oral fluid only requires 200 microl of sample and achieves limits of detection of 2 ng/ml, and has been used to analyze oral fluid samples collected from current drug users.

Calibration↗

PubMed2001

Utilization at high pH of starter cultures of lactobacilli for Spanish-style green olive fermentation.

Inoculation at alkaline pH (above 9) of lye-treated green olives with starter cultures of Lactobacillus pentosus CECT 5138 was studied. Despite an initial loss of viability in the order of 1-2 log cycles on average, depending mainly on time of application, cultures grew and initiated an accelerated fermentation process. Inoculation reduced the population of Enterobacteriaceae, and thereby potential spoilage, and produced a quicker acidification of brines and decrease of pH, when compared with control uninoculated batches. Results obtained throughout three consecutive seasons demonstrated that utilization at high pH of starter cultures of lactobacilli is feasible, provided that the inoculum size takes into account the initial low survival.

Fermentation↗

PubMed2000

Comparative study on chemical changes in olive juice and brine during green olive fermentation.

Changes in physicochemical characteristics, substrate depletion, and product formation during fermentation were followed in both brine and olive juice in order to achieve a complete knowledge of fermentation chemistry in Spanish-type green olives. Both spontaneous and controlled fermentations were investigated. Fermentation rate, irrespective of the type of fermentation, was lower in olive juice than in brine, but the main acid products eventually reached equilibrium. Final free acidity remained significantly (p < 0.05) higher, and combined acidity remained lower, in brine than in olive juice in both fermentations, but differences in final pH were not significant in controlled fermentation. Final concentrations of lactic and formic acids were significantly (p < 0. 05) higher, and those of ethanol and succinic acid were lower, in controlled fermentation than in spontaneous fermentation. Butanediol, attributable to Enterobacteriaceae growth, was formed only in the latter case. Calculated carbon recoveries were not significantly (p < 0.05) different in any case, giving a mean of some 78%.

Fermentation↗

PubMed1998

Lactic acid fermentation and storage of blanched garlic.

The controlled fermentation of peeled, blanched garlic, using a starter culture of Lactobacillus plantarum, was studied and compared with that of unblanched garlic. Blanching was carried out in hot water (90 degrees C) for 15 min. The starter grew abundantly in the case of blanched garlic, producing mainly lactic acid and reaching a pH of 3.8 after 7 days, but its growth was inhibited in unblanched garlic. Ethanol and fructose, coming from enzymatic activities of the garlic, and a green pigment were formed during the fermentation of unblanched garlic, but not of blanched garlic. The blanched garlic fermented by L. plantarum, even without a preservation treatment (pasteurization), was microbiologically stable during storage at 30 degrees C in an acidified brine (approximately 3% (w/w) NaCl and pH 3.5 at equilibrium), but fructans were hydrolyzed. The packed fermented product and that obtained by direct packing without fermentation were not significantly different with regard to flavour.

Carbohydrates↗

PubMed1997

Processing and storage of lye-treated carrots fermented by a mixed starter culture.

A mixed culture of Lactobacillus plantarum and Saccharomyces cerevisiae was compared with a single culture of L. plantarum as starter for the fermentation of lye-treated carrots. Using the mixed culture, more than 95% of glucose, fructose and malic acid was consumed after 7 days of fermentation in a brine containing 2.5% w/v NaCl and 0.7% acetic acid, but only 54% of sucrose was degraded. The fermentation products quantified were lactic acid, ethanol and acetic acid and carbon recovery was 88%. Using the single culture of L. plantarum, substrate consumption was lower, and carbon recovery almost 100%. In uninoculated lye-treated carrots, heterofermentative bacteria grew, with the production of considerable amounts of mannitol. In all cases, the stability, sensorial characteristics and carotenoid content of the packed product were studied during 9 months of storage at 30 degrees C, and two different preservation systems were compared: addition of preservatives, approximately 500 and 1000 mg/kg of sorbic and benzoic acid, respectively, and pasteurization at 80 degrees C for 10 min. The pasteurized samples were microbiologically stable during the storage period, while lactic acid bacteria grew in the samples with preservatives. Storage time significantly (P < 0.05) affected the texture and colour parameters (L*, a*, b*) of the carrots, but not the amounts of alpha- and beta-carotene. The type of fermentation had no significant effect on texture, colour parameters or carotenoid content. The preservation method had no significant effect on texture or carotenoid content, but did affect colour (parameter a*). The flavour of carrots fermented by the mixed culture was significantly (P < 0.05) preferred to that of those fermented with a single culture of L. plantarum.

Daucus carota↗

PubMed1993

A facial variant of steatocystoma multiplex.

A case of steatocystoma multiplex confined to the face is reported. Review of the literature disclosed similar cases in this striking location. We therefore believe that this facial variant is a distinctive but less well known variant of steatocystoma multiplex. We review the relationship between steatocystoma multiplex and eruptive vellus hair cysts.

Adult↗

PubMed1991

Malignant combined nevus.

This report describes an example of combined nevus with malignant transformation. The clinical impression was blue nevus. Histologically, the lesion was composed of a cellular blue nevus in the reticular dermis and an overlying compound melanocytic nevus. The junctional component of the melanocytic nevus showed transition to malignant melanoma in situ. A review of the literature failed to find a precedent for the present case.

Cell Nucleus↗

PubMed1991

Postlymphography linear dermatitis.

Cutaneous effects secondary to lymphography are rare events. We herein report a patient with Hodgkin's disease who developed a linear dermatitis in both lower limbs 6 days after a pedal lymphography. Histopathologic examination of the lesions demonstrated a subacute dermatitis. Patch tests with the substances used in the lymphography yielded negative results. We discuss the possible pathogenic mechanisms of this striking linear dermatitis.

Adult↗

PubMed1991

Linear pemphigus vulgaris along a surgical scar.

A 64-year-old female had breast carcinoma of the right breast, and a mastectomy was performed. Three years later she developed a vesiculobullous eruption along the surgical scar. Histopathological and direct immunofluorescence findings were consistent with a diagnosis of pemphigus vulgaris. We discuss the possible pathogenesis for this striking linear distribution of the pemphigus vulgaris lesions.

Breast Neoplasms↗

PubMed1991

Localized hyperkeratosis lenticularis perstans (Flegel's disease).

A case of hyperkeratosis lenticularis perstans involving only the back of a thirty-nine-year-old woman is reported. Histologic examination showed foci of compact and eosinophilic hyperkeratosis overlying a thinned stratum malpighii. In the underlying papillary dermis there was no evidence of inflammatory infiltrate. This case demonstrates that hyperkeratosis lenticularis perstans may appear as a localized disorder, and that the inflammation is not an essential pathogenic process in this disorder.

Adult↗

PubMed1991

[Cutaneous epithelial necrosis in coma. Study of 2 cases].

We report two cases of epithelial necrosis in comatous patients. The cutaneous lesions were characterized by erythematous plaques which later evolved to bullous lesions. Histologic examination demonstrated epidermal necrosis with subepidermal blisters, sparse neutrophilic inflammatory infiltrate and, characteristically, eosinophilic necrosis of the eccrine sweat gland coils.

Adult↗

PubMed1990

Trichoblastic fibroma.

We report a trichoblastic fibroma in the groin of a 60-year-old woman. This unusual tumor showed a predominance of epithelial component, with abundant basophilic, well-circumscribed, epithelial lobules and some keratinous cysts. Several areas suggested stromal induction of differentiation, and in the keratinous cysts there were indications of outer hair sheath differentiation. We review the clinical data from published cases of trichogenic hair germ tumors and discuss the differential diagnosis.

Epithelium↗

PubMed1988

Mechanism of action of high-load copper IUDs.

A comparative study was made of four intrauterine contraceptive devices: the Nova-T, MLCu250 Short, MLCu375, and the Gyne T. An endometrial biopsy was performed on the 25th day of the menstrual cycle. The tissue obtained was analyzed to determine estrogen and progesterone receptor concentration. After two years of IUD use, both estrogen and progesterone receptors decreased proportionally to the increased amount of copper in the IUD.

Adult↗

PubMed1988

Histological reactions of human endometrium to the IUD.

A comparative study was made of four intrauterine contraceptive devices: the Nova-T, MLCu250 Short, MLCu375 and the Gyne T. An endometrial biopsy was performed on the 25th day of the menstrual cycle. The tissue obtained was analyzed to determine endometrial morphology patterns. After two years of IUD use, no inflammatory changes were demonstrated with MLCu375. Histological responses of the endometrium to the IUD depend on the amount of copper in the IUD.

Adult↗

PubMed1988

Assessment of uterine shape and size using Kurz's Cavimeter.

The Kurz's Cavimeter was used to determine uterine shape and dimensions in 509 women prior to IUD insertion. The women were separated into six groups, depending on parity. A slight increase was noted in total uterine length due to endometrial cavity length and transverse fundal diameter in relationship to parity. However, the differences did not reach statistical significance.

Biometry↗

PubMed1987

Comparison of two copper IUDs: the MLCu375 and the Nova-T.

A comparative randomized trial was carried out on two intrauterine contraceptive devices: the Nova-T and the MLCu375. The IUDs were used by 1116 and 1237 women respectively, over a period of 2 years. The reasons for IUD removal were analyzed after one and two years using the life-table method. Statistically significant differences were found in the rates for pregnancy, expulsion and removal for bleeding and/or pain favoring the MLCu375 IUD.

Adolescent↗