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Biomedical subjects

N Lopez

Publications and source records attributed to N Lopez.

At least 37 records · Page 2Linked to original sources
PubMed1996

Multiparametric cell-cycle analysis of peripheral blood-activated lymphocyte subsets using staining based on the TdT method for incorporated BrdUrd.

This study describes a new method for the simultaneous assessment of the distribution of a cell population in the G0/G1, S, and G2/M cell-cycle phases by using multiparameter flow cytometry and single staining based on BrdUrd incorporation. Both the K562 cell line and PHA-stimulated peripheral blood lymphocytes (PBL) were analyzed. Cells were cultured in the presence of BrdUrd for 30 min prior to cell harvesting. Once collected, cells were exposed to ultraviolet light for 5 min and then fixed immediately in 70% ethanol (-20 degrees C) for at least 30 min. Once fixed, the cells were placed for 30 min at 37 degrees C in the presence of terminal deoxynucleotidyl transferase (TdT) and dUTP labeled with digoxigenin; they were then stained with FITC-labeled anti-digoxigenin. Our results show that G0/G1, s, and G2/M cell populations can be clearly discriminated according to FITC fluorescence and light-scatter parameters. In this way, S-phase cells can be identified by their FITC staining. From the cells which were negative for anti-digoxigenin-FITC antibody, two clear populations could be resolved in a forward scatter, side scatter, and fluorescence pulse-width three-dimensional plot; the values obtained for G0/G1 cells were lower than those obtained for G2/M cells in all three parameters. Multiparameter analysis of PBL stained for two surface antigens (CD3 and CD8) and for BrdUrd by direct or indirect TdT method permitted cell-cycle analysis of different subpopulations, including CD3+/CD8+, CD3+/CD8-, CD3-/CD8+, and CD3-/CD8-.

Bromodeoxyuridine↗
PubMed1996

Subjective refraction of the peripheral field using contrast detection acuity.

BACKGROUND: Although peripheral resolution acuity is relatively unaffected by uncorrected refractive error, recent investigations of peripheral vision indicate that contrast detection is optically limited. It should be possible, therefore, to perform a subjective refraction in the peripheral visual field using a contrast detection task. METHODS: For a range of trial lenses, contrast detection acuities for vertical and horizontal gratings were measured with a two-interval forced-choice paradigm. Lens powers that maximized detection acuity were taken as the subjective refraction estimates. These powers were compared with objective refractions determined with retinoscopy and autorefractometry. RESULTS: Contrast detection acuity varied significantly with lens power at all retinal locations tested. Defocusing by one diopter from the optimum lens power reduced detection acuity by about a factor of two at 20 degrees eccentricity, and slightly less in the far periphery. Objective retinoscopy and autorefractometry agreed with subjective measurements for most conditions tested. CONCLUSIONS: Contrast detection acuity in the peripheral visual field varies with refractive blur, demonstrating the feasibility of performing subjective refraction in the periphery for a contrast detection task. Results suggest that visual fields measured with standard perimetry, which is based on contrast detection, may be affected by uncorrected peripheral refractive errors.

Adult↗
PubMed1995

The L protein of Rift Valley fever virus can rescue viral ribonucleoproteins and transcribe synthetic genome-like RNA molecules.

Overlapping cDNAs representing the complete L segment of Rift Valley fever virus were assembled, and the L protein was expressed via a recombinant vaccinia virus. The transcriptase activity of the L protein was assayed with two types of templates: natural ribonucleoproteins (RNPs) and artificial genome-like RNAs. RNPs purified in a CsCl gradient did not retain the RNA polymerase function, but the activity was restored when the L cDNA was expressed in mammalian cells via a recombinant vaccinia virus. Indeed, after transfection of transcriptase-depleted RNPs in cells infected with the recombinant vaccinia virus expressing the L protein, the mRNAs coding for the N and NSs proteins and to a lesser extent, those coding for the glycoproteins were synthesized as well as the corresponding proteins. The transcriptase activity of the recombinant L protein was then investigated by using synthetic templates containing the reporter chloramphenicol acetyltransferase gene in the antisense orientation flanked by the 3' and 5' noncoding region of the S genomic segment. Our results indicate that after transfection of the RNA templates, transcription was achieved in cells coexpressing both the L and N proteins. Together, the experiments demonstrate that the two proteins N and L are absolutely required and sufficient to reconstitute the transcriptase activity.

Base Sequence↗
PubMed1995

Adenovirus-mediated gene transfer to human fetal lung ex vivo.

Gene therapy of the fetus or newborn infant is a potentially useful approach for prevention or treatment of specific lung diseases. To begin to address issues such as efficiency, duration, and cellular distribution of transgene expression, we studied transduction of human lung cells by recombinant, replication-deficient adenovirus containing the lacZ gene driven by the beta-actin promoter and cytomegalovirus enhancer (H5.010CBlacZ). Human fetal lungs of 20- to 24-wk gestation received approximately 10(11) viral particles by instillation into a major bronchus, and the tissue was cultured as explants in serum-free Waymouth's medium. beta-galactosidase staining (X-gal) was detected by 24 h in defined regions of treated tissue and localized to epithelial cells of airways and terminal saccules. beta-galactosidase activity in homogenate of treated tissue was maximal 3-5 days after exposure to virus, ranging from 0.2 to 1.5 A420.min-1.mg protein-1 in four experiments (control values were approximately 0.001). When virus was added directly to lung explants in culture, beta-galactosidase was expressed in most of the peripheral cells and rarely in interior cells, the level of activity was dose dependent between 10(8) and 10(11) viral particles/ml, and transgene expression was sustained for at least 28 days. Treatment of isolated cultured cells with virus resulted in equivalent staining of both epithelial cells and fibroblasts. We conclude that fetal lung cells are efficiently transduced by recombinant adenovirus, indicating the feasibility of gene therapy in the infant or fetus. Cultured fetal lung may be useful for testing gene constructs being considered for therapy.

Adenoviridae↗
PubMed1995

Characterization of clone 13, a naturally attenuated avirulent isolate of Rift Valley fever virus, which is altered in the small segment.

The 74HB59 strain of Rift Valley fever (RVF) virus, isolated from a human case in the Central African Republic, was shown to be composed of a heterogeneous population of viruses when plaque-purified clones were analyzed for their reactivity with monoclonal antibodies (MAbs) directed against the nucleocapsid (N) protein or the nonstructural (NSs) protein. One of these clones, C13, was of particular interest in that it proved to be avirulent in mice and hamsters, and highly immunogenic. Although C13 showed normal reactivity with a large panel of MAbs directed at the glycoproteins, it failed to react with specific MAbs or polyclonal antibodies directed at the NSs protein and with a specific MAb recognizing the N protein of the Egyptian strains. Consequently, the small RNA segment, which encodes the N and NSs proteins in an ambisense strategy, was sequenced and compared with the existing sequence of the attenuated MP-12 RVF virus strain. We found that the NSs gene contained, in addition to two conservative coding changes, a large internal deletion of 549 nucleotides that removes 69% of the open reading frame but conserves in-frame the N and C termini of the predicted translation product. In addition, the sequence revealed that the N protein of C13 contained a single amino acid change. Clone C13 replicated normally in certain cell types in vitro and in Culex pipiens mosquitoes after intrathoracic inoculation, but established abortive infections in MRC-5 human fibroblasts.

Animals↗
PubMed1993

Comparison of the Syva MicroTrak enzyme immunoassay and Gen-Probe PACE 2 with cell culture for diagnosis of cervical Chlamydia trachomatis infection in a high-prevalence female population.

Culture is currently considered the "gold standard" for detecting Chlamydia trachomatis infections. We evaluated the Syva MicroTrak enzyme immunoassay (EIA) and Gen-Probe PACE 2 tests, which detect chlamydial antigens and rRNA, respectively. These assays were compared with each other and with culture for the detection of C. trachomatis in cervical specimens obtained from 217 women attending a clinic for sexually transmitted diseases. The prevalence of infection was 22.1% by culture. The sensitivity, specificity, and positive and negative predictive values were 79.2, 98.2, 92.6, and 94.3%, respectively, for EIA. For PACE 2, the respective values were 77.1, 97.6, 90.1, and 93.7%. After corrections for two false-negative cultures, the sensitivities and specificities were 80 and 99.4%, respectively, for the EIA and 78 and 98.8%, respectively, for the probe assay. Quantitative evaluation of the results showed that false-negative results with either assay were associated with cultures that had low inclusion counts or were negative without subpassage. Analysis of nonculture results revealed that 2.3% of the EIA results and 4.6% of the probe assay results were within +/- 30% of the respective assay cutoff values. These included four false-negative (one EIA and three probe) and two false-positive (one EIA and one probe) results. The Syva MicroTrak EIA and the Gen-Probe PACE 2 assay are comparable to but significantly less sensitive than culture. Use of a grey zone may help identify the need for repeat or confirmatory testing.

Adolescent↗
PubMed1990

Pimozide enhances the aversiveness of quinine solution.

The taste reactivity test was employed to assess the effect of pimozide pretreatment on rats' hedonic responsiveness to palatable and unpalatable tastants. Pimozide selectively enhanced the aversiveness of unconditionally unpalatable quinine solution (Experiment 1) and produced the greatest enhancement of aversion at the highest concentration of quinine (0.1%) solution tested (Experiment 3). Pimozide also enhanced the aversiveness of a conditionally unpalatable lithium-paired solution, but only when the dose of pimozide was relatively high and the strength of the baseline aversion was relatively low (Experiment 2). These results are discussed in light of the anhedonia and the sensorimotor deficit hypotheses of neuroleptic effects on reinforced responding.

Animals↗
PubMed1989

Tacaribe virus L gene encodes a protein of 2210 amino acid residues.

The nucleotide sequence of Tacaribe virus (TV) L gene was obtained from two sets of overlapping cDNA clones constructed by walking along the virus L RNA using two successive synthetic DNA primers. Analysis of the sequence indicated the existence of a unique long open reading frame in the viral complementary strand. The first in-phase AUG codon is in positions 31-33 from the 5' end of the viral complementary L RNA surrounded by a sequence favorable for initiation of protein synthesis. The open reading frame ends at positions 6661-6663. The predicted TV L protein is a 2210 amino acid long polypeptide with an estimated molecular weight of 251,942. Comparison of the amino acid sequence of TV L protein with peptide sequences predicted from L-derived cDNA clones of lymphocytic choriomeningitis virus shows an overall 42% of homology.

Amino Acid Sequence↗
PubMed1989

Renin release responses to in vitro prostaglandin challenge in the summer-active ground squirrel, Spermophilus lateralis.

1. Using a renal cortical slice preparation from the summer-active ground squirrel, Spermophilus lateralis, resting renin release (RR) and tissue cyclic AMP content (TcAMPC) levels were found to be significantly higher and lower, respectively, than those previously reported for its hibernating counterpart. 2. At a 10(-5) M dose, PGE2 but not PGE1, PGF2-alpha or PGA1, significantly stimulated RR in the summer-active ground squirrel (SAGS). 3. Addition of agents which normally increase TcAMPC significantly potentiated the effect of PGE1, while preventing that of PGE2, on RR and TcAMPC. 4. Opposite TcAMPC changes may mediate the in vitro RR responses to PGE1 and PGE2 administration in the SAGS.

Alprostadil↗
PubMed1988

Disposition of bemitradine, a renal vasodilator and diuretic, in man.

1. 14C-Bemitradine (50 mg) was rapidly and efficiently absorbed (approximately 89%) in man following a single oral dose, as a solution in gelatine capsules. Peak 14C levels of 895 +/- 154 ng equiv./ml (mean +/- S.E.M.) were reached within 2 h, and declined with half-lives of 1.07 +/- 0.25 and 13.0 +/- 5.6h. 2. No bemitradine was detected in plasma, but peak concn. (124 +/- 29 ng/ml) of its desethyl metabolite were reached at 1.05 +/- 0.28 h, and declined with a half-life of 1.32 +/- 0.08 h. 3. Desethylbemitradine was rapidly metabolized to its ether glucuronide, a phenol and a dihydrodiol which were also present as glucuronide conjugates. The glucuronides were the major compounds in plasma from 2 h after drug administration. 4. Excretion in 5 days amounted to 88.8 +/- 2.3% and 10.4 +/- 2.1% dose in urine and faeces respectively. No bemitradine or desethylbemitradine were excreted unchanged. 8-(2-Hydroxyethyl)-7-(3,4- dihydroxycyclohexa-1,5-dienyl)-1,2,4-triazolo-1,5c-pyrimidin e-5-amine (E; 17% dose); 8-(2-hydroxyethyl)-7-(4-hydroxyphenyl)-1,2,4-triazolo-1,5c- pyrimidine-5-amine (F; 4% dose), their glucuronides (A, 19% dose and B, 6% dose respectively), desethylbemitradine glucuronide (D, 25% dose) and an unidentified metabolite (C, 12% dose) were excreted in urine. Compound F was the major faecal metabolite.

Absorption↗
PubMed1986

Prostaglandin E1 (PGE1) stimulates in vitro renin release in the hibernating ground squirrel.

Using a renal cortical slice preparation obtained from hibernating ground squirrels, this study investigated whether three major intrarenal prostaglandins (PG) and other agents added at a 10(-5) M dose can affect renin release (RR), and if their effect on RR is correlated with changes in tissue cyclic AMP content (tcAMPc). Resting in vitro levels for RR and tcAMPc during hibernation were found to be comparable to those observed in non-hibernating (NH) mammals. Addition of PGE1 significantly stimulated RR while PGE2 and PGF2-alpha were ineffective. None of the three PG's tested altered resting levels of tcAMPC. When added by itself or in conjunction with any of the three PG's, the phosphodiesterase inhibitor theophylline did not modify resting levels of RR and tcAMPc, but it prevented the previous stimulatory effect of PGE1 alone on RR. Addition of lipid-soluble dcAMP, either alone or in conjunction with any of the three PG's, resulted in an increase in tcAMPc in all instances, no change in resting RR regarding PGE2 and PGF2-alpha, and again the prevention of the stimulatory effect of PGE1 alone on RR. These data suggest that: the resting activity of the renin-angiotensin system (RAS) and the adenylate cyclase-cAMP system (AC-cAMP) of the hibernating ground squirrel is comparable to that of NH species; in contrast, the sensitivity of the RAS of the hibernator to PG stimulation is less than that exhibited by the RAS of NH species when comparable in vitro concentrations of three major PG's are used; PGE1 stimulation of RR in the hibernator is independent of changes in tcAMPc; changes in tcAMPc may be inversely related to those in RR in the hibernator; and the known stimulatory effect of PG's on the renal cortical AC-cAMP of NH species is not seen in the hibernating ground squirrel at comparable PG doses.

Adenylyl Cyclases↗
PubMed1976

Metastatic adenocarcinoma of gingiva. Report of a case.

A case of metastatic neoplasm developing in the gingiva from a primary lesion, probably sited in the gastric mucosa, has been reported. In this case, the first demonstrable metastatic lesion was located in the gingiva. The dentist has a great responsibility in detecting malignancy in the oral cavity because of his opportunities during routine examinations.

Adenocarcinoma↗