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J J Palacios

Publications and source records attributed to J J Palacios.

13 recordsLinked to original sources
PubMed2003

First-principles phase-coherent transport in metallic nanotubes with realistic contacts.

We present first-principles calculations of phase coherent electron transport in a carbon nanotube (CNT) with realistic contacts. We focus on the zero-bias response of open metallic CNT's considering two archetypal contact geometries (end and side) and three commonly used metals as electrodes (Al, Au, and Ti). Our ab initio electrical transport calculations make, for the first time, quantitative predictions on the contact transparency and the transport properties of finite metallic CNT's. Al and Au turn out to make poor contacts while Ti is the best option of the three.

Journal Article↗
PubMed2003

[Parotid tuberculosis following intravesical BCG instillation: a case report].

First case of parotid gland tuberculosis publicated to date is presented after intravesical instillation of BCG for a superficial bladder cancer. The diagnosis of the parotid gland tuberculosis is difficult because it is usually indistinguishable from a neoplasm. Combined fine-needle aspiration cytology with PCR or LCR amplification of mycobacterial DNA could be a good diagnostic tool avoiding an open biopsy.

Administration, Intravesical↗
PubMed2000

Prognostic value of tumoral ploidy in a series of spanish patients with acute lymphoblastic leukemia.

The prognostic value of tumoral ploidy and its relation with nonrandom chromosome alterations were analyzed in 89 cases of acute lymphoblastic leukemia. Ploidy is associated with the number of nonrandom chromosome alterations and survival. The pseudodiploid and hypodiploid groups had a high incidence of nonrandom alterations and poor survival while the diploid and high hyperdiploid groups had a lower incidence of nonrandom alterations and longer survivals. The patients in the low hyperdiploid group with random alterations received the same treatment as the diploid and high hyperdiploid groups but had poor survivals. Our analysis confirms that ploidy is a very important prognostic factor and suggests that patients with low hyperdiploidy should receive intensive therapies similar to those of patients in the groups with a high number of nonrandom alterations.

Adolescent↗
PubMed1999

Fully automated liquid culture system compared with Löwenstein-Jensen solid medium for rapid recovery of mycobacteria from clinical samples.

The aim of this study was to compare the rate of recovery of mycobacteria and the time to detection in 5208 samples using the MB/BacT culture system (Organon Teknika, USA) and Löwenstein-Jensen medium. Mycobacteria were recovered from 301 (5.7%) samples. Two hundred fifty-seven (85.3%) isolates from 114 patients were Mycobacterium tuberculosis [135 (52.5%) smear-positive, 122 (47.4%) smear-negative], and 44 (14.6%) were potentially pathogenic environmental mycobacteria. The yield with the MB/BacT was higher than that with Löwenstein-Jensen [287 (95.3%) vs. 200 (66.4%), P<0.001] for both Mycobacterium tuberculosis [247 (96.1%) vs. 187 (72.7%), P<0.001] and potentially pathogenic environmental mycobacteria [40 (90.9%) vs. 13 (29.5%), P<0.001], mainly at the expense of the smear-negative samples. Moreover, 70 (27.2%) samples were positive only in the MB/BacT, whereas ten (3.8%) samples were positive only in Löwenstein-Jensen. The number of patients with tuberculosis detected by the MB/BacT was higher than that detected by Löwenstein-Jensen medium [111 (97.3%) vs. 89 (78%), P<0.001]. In 25 (21.9%) patients the diagnosis was established solely by means of the MB/BacT. In smear-positive and smear-negative samples, the mean times to detection of Mycobacterium tuberculosis were 16.7 and 26.3 days, respectively, with Löwenstein-Jensen and 11.5 and 19.3 days, respectively, with the MB/BacT. These results indicate that the MB/BacT is more efficient and faster than Löwenstein-Jensen for the recovery of mycobacteria.

Bacteriological Techniques↗
PubMed1998

Comparison of the ligase chain reaction with solid and liquid culture media for routine detection of Mycobacterium tuberculosis in nonrespiratory specimens.

The aim of this study was to compare the results of a commercial assay based on the ligase chain reaction [(LCR) LCx Probe System MTB; Abbott, USA] with those of culture in liquid medium (Septi-Chek AFB; Becton-Dickinson, USA) and culture on the egg-based Löwenstein-Jensen solid medium for the direct detection of Mycobacterium tuberculosis complex in nonrespiratory specimens. The results were analyzed according to the standard definition of a true-positive result. Two hundred thirty-five nonrespiratory samples routinely submitted to rule out tuberculosis were analyzed. All samples were smear-negative. Mycobacterial growth in either culture medium was detected in 18 (7.6%) specimens: Mycobacterium tuberculosis was recovered from seven (38.9%) specimens cultured on Löwenstein-Jensen medium and from 18 (100%) specimens cultured in Septi-Chek AFB. The LCR protocol was positive in 22 specimens. None of the LCR-negative controls showed positive results. All samples positive by culture on Löwenstein-Jensen medium were positive by culture in liquid medium and by the LCR assay. However, Mycobacterium tuberculosis was detected by culture in liquid medium in two specimens that were negative by the LCR assay, whereas six specimens negative by culture in liquid medium were positive by the LCR protocol; three of these were identified as true-positive results of the LCR assay. The sensitivity, specificity, and positive and negative predictive values were 33.3%, 100%, 100%, and 93.8%, respectively, for Löwenstein-Jensen medium; 85.7%, 100%, 100%, and 98.6% for the liquid medium; and 90.4%, 98.5%, 86.3%, and 99% for the LCR assay. These findings indicate that the LCR assay may be a valid method of high diagnostic yield for direct detection of Mycobacterium tuberculosis complex in nonrespiratory specimens.

Body Fluids↗
PubMed1997

Comparison of MB-check and Löwenstein-Jensen media for recovery of mycobacteria.

We have compared the rate of recovery of mycobacteria with the MB-Check culture system (liquid phase) and the Löwenstein-Jensen (LJ) medium in 2,907 clinical specimens obtained from 830 patients submitted for mycobacterial culture during 1-year period. Direct smear examination was carried out by auramine-rhodamine staining. All primary isolates from the culture media were confirmed by Ziehl-Neelsen staining and identified by acridinium-ester-labeled DNA probes specific for Mycobaterium tuberculosis complex. A total of 214 isolates were of the M. tuberculosis complex (88 patients) and 54 of "potentially pathogenic environmental mycobacteria" (45 patients). A total of 117 (54.7%) samples were smear-positive and the remaining 97 (45.3%) were smear-negative. There was a significant difference in the percentage of positive cultures obtained by the MB-Check method (99.1%) as compared with the LJ medium (73.8%) (P < 0.05). This difference, however, occurred almost exclusively at the expense of the 97 smear-negative samples (positive cultures 97.95% by the MB-Check method vs. 42.3% by the LJ culture, P < 0.05). The number of patients diagnosed of tuberculosis by the MB-Check was significantly higher as compared with LJ medium (88 [100%] vs. 77 [87.5%], P < 0.05). In 11 (12.5%) patients, the diagnosis was only established by the MB-Check system. In smear-positive samples, the mean (+/-SD) detection time for M. tuberculosis complex was 14.8 +/- 8 days with MB-Check and 19.9 +/- 7 days with LJ medium. The corresponding figures in smear-negative samples were 22.8 +/- 3 days and 27.8 +/- 6 days, respectively. DNA probes directly applied to MB-Check liquid medium showed a sensitivity of 98.8% and specificity of 100%. These results indicate that the MB-Check system is more efficient for the recovery of mycobacteria than LJ medium.

Bacterial Typing Techniques↗
PubMed1997

[Cervicofacial actinomycosis].

Actinomycosis is an infectious disease that appears throught the world, in cattle and human beings. It is a chronic granulomatous and suppurative lesion, usually affecting the cervicofacial area. Definitive diagnosis, by culture or biopsy, is not always possible, so the clinician must suspect it by its clinical presentation. It is the purpose of this article to present the patients diagnosed and treated in our Department during the last 5 years, and to review the ideal therapy.

Actinomycosis, Cervicofacial↗
PubMed1996

Comparison of solid and liquid culture media with polymerase chain reaction for detection of Mycobacterium tuberculosis in clinical samples.

The aim of this study was to determine the sensitivity of different methods--two commercial polymerase chain reaction (PCR) kits (a protocol of nested PCR and a protocol of amplification of the IS6110 insertion element), the radiometric Bactec system, the Septi-Chek AFB culture system, and culture in Löwenstein-Jensen (LJ) solid medium--for the detection of Mycobacterium tuberculosis. One hundred clinical samples from 51 patients with culture-positive tuberculosis (81 specimens) and 19 controls (19 specimens) were used. Eighty-nine percent of the samples were smear negative. In the 81 specimens obtained from patients with tuberculosis, the frequency of positivity was 66.6% for nested PCR, 63% for culture in liquid media, 38.3% for IS6110 assay, and 28.4% for culture in LJ medium. In 18 samples obtained by invasive procedures in patients with tuberculosis, mycobacterial DNA was detected by nested PCR in 83.3% (including all samples positive by culture on liquid media), by culture in liquid media in 77.7% by culture on LJ medium in 27.7%, and by the IS6110 assay in 11.1%. No false-positive results were obtained from the negative control specimens with any of the techniques tested. The sensitivity of the reamplification protocol appears to be superior to that of the IS6110 assay and similar to that of the Bactec system.

Culture Media↗
PubMed1979

Sclerosing hemangioma of the lung: an ultrastructural study.

A well-circumscribed nodular mass was excised from the lingula of the left lung of a 40-year-old-female. The lesion was discovered on routine chest x-ray examination and corresponded to a typical "sclerosing hemangioma" described by Liebow and Hubbell. Electron microscopic study revealed unequivocal epithelial cells in both the irregular spaces and the solid areas of the tumor; some of these cells were identical to granular pneumonocytes. The true vascular component was sparsely distributed. We concluded that "sclerosing hemangioma" was a misnomer because we were dealing with an essentially epithelial lesion.

Adult↗