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L Carvajal

Publications and source records attributed to L Carvajal.

15 recordsLinked to original sources
PubMed2005

Fast high performance liquid chromatography and ultraviolet-visible quantification of principal phenolic antioxidants in fresh rosemary.

An improved HPLC method is reported for the determination of rosemary's principal phenolic antioxidants, rosmarinic and carnosic acids, providing a fast and simultaneous determination for both of them by using a solid phase column. The analysis was performed with fresh methanolic extractions of Rosmarinus officinalis. To quantify the amount of antioxidants in a fast and reproducible way by means of UV-vis absorption measurements, a spectrophotometric multi-wavelength calibration curve was constructed based on the antioxidant contents obtained with the recently developed HPLC method. This UV-vis methodology can be extended to the determination of other compounds and herbs if the restrictions mentioned in the text are respected.

Antioxidants↗
PubMed2000

[Antimicrobial resistance of Shigella spp. in Córdoba, Argentina, during the period 1990-1997].

This study analyzed the evolution of antimicrobial resistance in 771 isolates of Shigella spp. obtained from a total of 9,195 feces cultures done between 1990 and 1997 in a children's hospital in Córdoba, Argentina. S. flexneri, which was responsible for 73% of the Shigella infections, was the species with the greatest resistance. The frequency of S. flexneri resistance to the three antibiotics most used (ampicillin, trimethoprim-sulfamethoxazole, and chloramphenicol) increased from 10% in 1990 to 58% in 1997 (P < 0.001). Considering each of the drugs individually, the resistance to ampicillin increased from 60% to 100% (P < 0.001), the resistance to chloramphenicol from 13% to 71% (P < 0.001), and the resistance to trimethoprim-sulfamethoxazole from 79% to 84% (P = 0.22). For S. sonnei, the increase in resistance to ampicillin (from 36% in 1990 to 54% in 1997) was not statistically significant (P = 0.20), nor was the reduction in resistance to trimethoprim-sulfamethoxazole, which went from 82% in 1990 to 55% in 1997 (P = 0.08). Only two S. sonnei isolates were found that were resistant to chloramphenicol, one in 1995 and another in 1997; two S. sonnei isolates were found with resistance to all three antibiotics. We consider it essential to carry out susceptibility tests of each Shigella clinical isolate, to detect changes in the resistance profile and thus modify empiric treatment.

Ampicillin↗
PubMed1995

Phased array detectors and an automated intensity-correction algorithm for high-resolution MR imaging of the human brain.

Two- and four-coil phased array detectors were developed to increase the sensitivity and resolution of MR imaging of the human brain cortex, especially for detecting cortical dysplasias in pediatric epilepsy patients. An automated intensity correction algorithm based on an edge-completed, low-pass filtered image was used to correct the image intensity for the inhomogenous reception profile of the coils. Seven phased array coils were constructed and tested. The sensitivity of these coils was up to 600% higher at the surface of the cortex than that achieved with a conventional head coil and up to 30% greater at the center of the head. The sensitivity obtained was comparable with that of a conventional small surface coil, but extended over the larger dimensions of the array and previously inaccessible areas such as the top of the head. The advantages of the improved sensitivity are demonstrated with high resolution images of the brain.

Adult↗
PubMed1994

Two configurations of the four-ring birdcage coil for 1H imaging and 1H-decoupled 31P spectroscopy of the human head.

The four-ring birdcage resonator, a new class of dual-tuned birdcage resonators, is described. We report two configurations of the coil: the low-pass, high-pass (LP-HP) and the low-pass, low-pass (LP-LP), both of which can be operated in dual quadrature mode at 1.5 T. As head coils, both configurations exhibit greatly reduced tuning interactions between frequencies, permitting rapid, noniterative tuning. Compared with single-tuned, two-ring birdcage resonators of similar volume, the sensitivity and transmitter efficiencies of the resonators are better than 85% for the proton frequency and the same to within 5% for the phosphorus frequency. Circuit models have been developed to refine coil tuning and aid the calculation of B1 field contour plots. Both configurations have been used for integrated examinations involving acquisition of high-quality 1H images and 1H-decoupled 31P CSI spectra of the human head. A scaled-down version of the LP-LP configuration has been demonstrated for use with the human calf.

Head↗
PubMed1990

1H MR imaging of anatomical compartments within the finger flexor muscles of the human forearm.

Fast T2-weighted 1H MRI following exercise allows investigation of the location of muscle fiber activity within skeletal muscle. Using this method, we have demonstrated that the finger flexor muscles of the human forearm consist of anatomical compartments, located at various depths, which are involved individually in flexion of the index, middle, or ring and little fingers. The results of this study indicate that the exercise protocol in 31P MRS studies of the finger flexor muscles of the human forearm, in which a small surface coil is used for detection, should be carefully reviewed.

Adult↗
PubMed1987

[Cystic adenoid carcinoma. Apropos of 2 cases originating in the salivary glands].

The CAQ is a tumor of the major and minor salivary glands, of superior airway glands, uterine cervix glands, and the Bartholin glands of the vulva. However, recently, primary cases of CAQ of the skin, originating in eccrine sweat glands were described. We report 2 CAQ cases, one, case 1, of minor salivary glands of the palate, that by extension, reached the skin of the face, finishing with kidney metastasis; and its histological type corresponded to the cribiform variety in both the primary tumor and the kidney metastasis. Case 2 presented in the parotid gland and its histological type is the solid variety of the CAQ.

Adult↗
PubMed1987

[Pilomatrixoma. Pseudoampullar form and other clinical varieties].

Pilomatrixoma presents clinical variants, ulcerated and tumorous, angioid and one very special type characterized because the skin covering the tumor is very thin (anetodermic), pink and folded, simulating an involuting blister. The authors that observed six cases of this variant, considered that for this reason they can name it the "pseudoblistering form of pilomatrixoma". The histopathology that appears in this pseudoblistering variant is characteristic because the collagen existing between the tumor and the epidermis is atrophied and its fibers are separated by the intense edema.

Adolescent↗
PubMedDate not supplied

[Streptococcus pneumoniae: evolution of antibiotic resistance in a pediatric hospital in Córdoba, Argentina].

The wide variety of prevalence of antimicrobial resistant Streptococcus pneumoniae in different countries confirms the importance of determining local patterns of resistance. From 1992 to 2000, we studied the pattern of antimicrobial resistance in S. pneumoniae and its evolution along the years, using 468 strains isolated in the Hospital de Niños de Córdoba. A total of 177 isolates (37.8%) were not susceptible to penicillin, with 19% intermediate and 18.8% resistant strains. High and intermediate resistance levels to cefotaxime were 4.9% and 10.9%, respectively. Decreased susceptibility to trimethoprim/sulfamethoxazole (TMS), erythromycin, chloramphenicol, and rifampin was found in 194 isolates (41.5%), 32 (6.8%), 13 (2.8%) and 3 (0.6%), respectively. No isolates resistant to vancomycin were detected. The most commonly combined resistance patterns were: penicillin/TMS (35.6%) and penicillin/TMS/cefotaxime (11.8%). This study highlights the increased rate of drug resistant S. pneumoniae during the last years, and the importance of antimicrobial resistance surveillance of adequate empirical therapy involving local and regional susceptibility patterns.

Adolescent↗
PubMedDate not supplied

[Extended-spectrum beta-lactamases in Klebsiella pneumoniae isolated at the Cordoba Children's Hospital, Argentina].

The aim of the present study was to investigate the presence of extended-spectrum beta-lactamases (ESBL) in Klebsiella pneumoniae isolated at the "Hospital de Niños de Córdoba". The strains were collected from inpatients between January 1996 and July 2000. A total of 150 ESBL producer isolates were detected. During 1996 the prevalence of ESBL producer K. pneumoniae was 20%, but since 1998 the values have increased to approximately 60%. Phenotypic analysis such as isoelectric point (pl) and antibiotyping performed in 32 randomly selected isolates showed two different enzyme profiles: 81% had ESBL with pl = 7.9 and preferential activity against cefotaxime, while 19% showed ESBL with pl = 5.4 and preferential activity against ceftazidime. No isolates resistant to imipenem or ciprofloxacin were detected. Susceptibility to other antimicrobial agents varied, but resistance to gentamicin was strongly associated with ESBL producer isolates. Resistance determinants could be transferred to Escherichia coli by conjugation assays.

Anti-Bacterial Agents↗
PubMedDate not supplied

[Colorectal cancer. Experience in 120 patients].

The medical records of 120 patients with Colo-Rectal Cancer who were admitted between 1983 and 1990, were reviewed. The clinical, radiologic, epidemiologic, endoscopic and pathologic characteristic were analyzed in all the patients; also their follow up related to Age, CEA, Dukes and treatment. Late stage diagnosis (10.8% of the cases were diagnosed during obstructive episodes, and 48.3% of the cases were Dukes C and D) and the high mortality (34.1% of the patients died within the first year of the diagnosis), are still basic problems to be solved. The high percentage of patients less than 40 years old (25.8%) and the high incidence of rectal localization of the disease (49.1%), must prompt us to attempt to control the disease by means of colonic evaluation in young people with symptoms attributable to Hemorrhoids or Amebiasis.

Adolescent↗