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Biomedical subjects

A Lopez

Publications and source records attributed to A Lopez.

At least 19 recordsLinked to original sources
PubMed1995

Quantification of pneumothorax size on chest radiographs using interpleural distances: regression analysis based on volume measurements from helical CT.

OBJECTIVE: The aim of this study was to define the relationship between interpleural distance measurements on an erect posteroanterior chest radiograph and pneumothorax size as measured by helical CT in a series of patients. SUBJECTS AND METHODS: Twenty pneumothoraces from 19 patients (10 males, nine females) were analyzed. Most pneumothoraces were on the right side (n = 16). The etiology was spontaneous in seven patients and iatrogenic in thirteen. All patients underwent an erect inspiratory posteroanterior radiograph and a helical CT scan of the thorax on the same visit to the radiology department. The interpleural distance was measured at three locations and the figures added together. Following helical CT of the thorax, the percentage pneumothorax size was calculated by drawing regions of interest around the relevant hemithorax and lung on 10-mm reconstructed slices. A scattergram of the sum of interpleural distances in centimeters versus percentage pneumothorax size was plotted. RESULTS: Analysis of results showed that percentage pneumothorax size could be calculated by the formula Y = 4.2 + [4.7 x (A + B + C)], r = .98, p < .0001. CONCLUSION: This study identified a formula for accurately calculating percentage pneumothorax size as determined by helical CT from an erect posteroanterior radiograph. Using this formula with the clinical status of the patient should more easily identify patients requiring active intervention.

Adolescent↗
PubMed1995

Flow cytometric DNA analysis of fine-needle aspirates of prostatic benign lesions.

Fine-needle aspiration samples from 54 consecutive patients suffering from prostatic benign lesions were analyzed for both cytological diagnosis and DNA cell content, by means of standard cytological criteria and flow cytometry, respectively. Of these patients, 13 displayed prostatitis: three being classified as acute prostatitis, 7 as chronic and 3 as granulomatosous prostatitis. All cases had a diploid DNA cell content, with a mean percentage of S-phase cells of 1.8 +/- 2.7%. Although no major differences were detected between patients with and without prostatitis, the former group had a slightly higher proportion of S-phase cells (1.4 +/- 2.2% vs 2.7 +/- 3.7%). Moreover, within those patients with prostatitis, acute prostatitis cases showed the highest proliferation rates although differences did not reach statistical significance.

Biopsy, Needle↗
PubMed1994

Influence of obstacles on lipid lateral diffusion: computer simulation of FRAP experiments and application to proteoliposomes and biomembranes.

Fluorescence Recovery After Photobleaching experiments were simulated using a computer approach in which a membrane lipid leaflet was mimicked using a triangular lattice obstructed with randomly distributed immobile and non-overlapping circular obstacles. Influence of the radius r and area fraction c of these obstacles and of the radius R of the observation area on the relative diffusion coefficient D* (Eq. (1)) and mobile fraction M was analyzed. A phenomenological equation relating D* to r and c was established. Fitting this equation to the FRAP data we obtained with the probe NBD-PC embedded in bacteriorhodopsin/egg-PC multilayers suggests that this transmembrane protein rigidifies the surrounding lipid phase over a distance of about 18 A (approximately equal to two lipid layers) from the protein surface. In contrast, analysis of published diffusion constants obtained for lipids in the presence of gramicidin suggests that in terms of lateral diffusion, this relatively small polypeptide does not significantly affect the surrounding lipid phase. With respect to the mobile fraction M, and for point obstacles above the percolation threshold, an increase in R led to a decrease in M which can be associated with the existence of closed domains whose average size and diffusion properties can be determined. Adaptation of this model to the re-interpretation of the FRAP data obtained by Yechiel and Edidin (J Cell Biol (1987) 115:755-760) for the plasma membrane of human fibroblasts consistently leads to the suggestion that the lateral organization of this membrane would be of the confined type, with closed lipid domains of approximately equal to 0.5 microns 2 in area.

Bacteriorhodopsins↗
PubMed1994

Transrectal fine needle aspiration biopsy of the prostate combining cytomorphologic, DNA ploidy status and cell cycle distribution studies.

Fine needle aspiration (FNA) cytology of the prostate is becoming a common diagnostic procedure, and DNA flow cytometry (FCM) data have been shown to correlate with the pattern of evolution of prostatic carcinoma, thus emphasizing the importance of assessing both parameters together. The aim of the present paper is to analyze the presence of DNA aneuploidy, cell cycle distribution and their relationship with the cytologic grade in transrectal fine needle aspiration prostate biopsies from 78 consecutive patients. Herein we studied the DNA ploidy status, the cell cycle distribution and their relationship with cytologic grade in transrectal FNA biopsies of the prostate from 78 consecutive patients -47 benign hyperplasias and 31 carcinomas- as analyzed by a reproducible FCM method for single cell suspension preparations, data acquisition and analysis. The presence of DNA aneuploidy was detected in 39% of the carcinomas and it was found to be a specific marker for prostatic carcinoma since all benign hyperplasia cases were diploid. Moreover, the incidence of DNA aneuploidy increased progressively from well-differentiated to moderately-differentiated and poorly-differentiated carcinomas (p = 0.005). Regarding cell cycle distribution, carcinomas displayed a higher proportion of both S-phase (p = 0.0003) and G2/M-phase (p = 0.0006) cells with respect to benign hyperplasias. Aneuploid cases also showed a greater proliferation rate as compared to the diploid carcinomas, regardless of their cytopathologic grade (p = 0.00001). Despite the fore-mentioned results, these correlations were far from being absolute, suggesting that combined assessment of these parameters should give additional information for the clinical management of prostatic disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Biopsy, Needle↗
PubMed1992

Thermal denaturation of plastocyanin: the effect of oxidation state, reductants, and anaerobicity.

The thermal stability of plastocyanin (PC) was determined as a function of oxidation state of the copper center and the presence of oxidants, reductants, oxygen, and EDTA. It was found that the copper center and its ligands play a crucial role in maintaining the stability of PC. Thermal denaturation was monitored by using far-uv circular dichroism (CD) spectra to monitor changes in secondary structure, the near-uv CD ellipticity at 280 nm to monitor changes in tertiary structure, and the absorbance at 597 nm and the 255-nm CD transition to monitor changes in the copper center. Reduced PC (Tm = 71 degrees C) was found to be more stable than the oxidized form (Tm = 61 degrees C). The Tm was increased by addition of reductants, removal of oxygen, or addition of EDTA. Two distinct denatured forms (designated D1 and D2) were separated by anion exchange fast protein liquid chromatography. Neither form contained a native copper center. Form D2 retained the characteristic 280-nm CD band but showed an altered far-uv CD spectrum. Its formation was inhibited by the addition of reductants or the removal of oxygen. It could be refolded to form native, Cu-PC upon incubation with copper plus a reductant such as dithionite. These results suggest that its formation involves the reversible oxidation of a group on the PC molecule, possibly a ligand to the copper such as Cys 84 or Met 92. Form D1 occurred in the presence of ferricyanide or at high temperatures in the presence of oxygen. EDTA inhibited its formation. Form D1 lost the 280-nm CD transition and its far-uv CD spectrum was altered. No renaturation was observed suggesting that Form D1 is the product of an irreversible oxidation step possibly involving a histidine ligand to the copper. Forms D1 and D2 are not interconvertible and represent the endpoints of two different denaturation pathways.

Anaerobiosis↗
PubMed1992

Polarity of lipid bilayers. A fluorescence investigation.

Through steady-state and time-resolved fluorescence experiments, the polarity of the bilayers of egg phosphatidylcholine vesicles was studied by means of the solvatochromic 2-anthroyl fluorophore which we have recently introduced for investigating the environmental micropolarity of membranes and which was incorporated synthetically in phosphatidylcholine molecules (anthroyl-PC) in the form of 8-(2-anthroyl)octanoic acid. Fluorescence quenching experiments carried out with N,N-dimethylaniline and 12-doxylstearic acid as quenchers showed that the 2-anthroyl chromophore was located in depth in the hydrophobic region of the lipid bilayer corresponding to the C9-C16 segment of the acyl chains. Steady-state fluorescence spectroscopy revealed a nonstructured and red-shifted (lambda em(max) = 464 nm) spectrum for the probe in egg-PC bilayers, which greatly differed from the structured and blue (lambda em(max) = 404 nm) spectrum the fluorophore was shown to display in n-hexane. While the fluorescence decays of the fluorophore in organic solvents were monoexponential, three exponentials were required to account for the fluorescence decays of anthroyl-PC in egg-PC vesicles, with average characteristic times of 1.5 ns, 5.5 ns, and 20 ns. These lifetime values were independent of the emission wavelength used. Addition of cholesterol to the lipid did not alter these tau values. One just observed an increase in the fractional population of the 1.5-ns short-living species detrimental to the population of the 20-ns long-living ones. These observations enabled time-resolved fluorescence spectroscopy measurements to be achieved in the case of the 1/1 (mol/mol) egg-PC/cholesterol mixture. Three distinct decay associated spectra (DAS) were recorded, with maximum emission wavelengths, respectively, of 410 nm, 440 nm, and 477 nm for the 1.5-ns, 6-ns, and 20-ns lifetimes found in this system. On account of the properties and the polarity scale previously established for the 2-anthroyl chromophore in organic solvents, these data strongly suggest the occurrence of three distinct excited states for anthroyl-PC in egg-PC bilayers, corresponding to three environments for the 2-anthroyl chromophore, differing in polarity. The lifetime of 1.5 ns and the corresponding structured and blue (lambda em(max) = 410 nm) DAS account for a hydrophobic environment, with an apparent dielectric constant of 2, which is that expected for the hydrophobic core of the lipid bilayer.(ABSTRACT TRUNCATED AT 400 WORDS)

Cholesterol↗
PubMed1992

Outbreak of human rabies in the Peruvian jungle.

Transmission of rabies to man by vampire bats has been known for 60 years but there have been few reports of the features of rabies transmitted in this way. These aspects of the disease were investigated during an outbreak in Peru in early 1990. Between Jan 1 and April 30, 1990, 29 (5%) of 636 residents of the two rural communities in the Amazon Jungle in Peru acquired an illness characterised by hydrophobia, fever, and headache and died shortly thereafter. A census in one of the two towns revealed that the proportion affected was significantly higher for 5-14 year olds (17%) than for other age-groups (p less than 10(-5). Interviews conducted with 23 of the patients or their families revealed that 22 (96%) had a history of bat bite, compared with 66 (22%) of 301 community members who remained healthy (p less than 10(-6). A rabies virus strain identical to those isolated from vampire bats (Desmodus rotundus) was isolated from the brain of the only person on whom necropsy could be done. Because of the extreme isolation of this and other communities affected by bat-transmitted rabies, preventive measures should be directed at decreasing the risk of nocturnal exposure to bats by bat proofing dwellings or use of mosquito nets and at prompt wound care. Rabies pre-exposure or postexposure vaccination is clearly indicated, but may not be feasible in these isolated populations.

Adolescent↗
PubMed1992

Comparison of eight different procedures for harvesting avian reoviruses grown in Vero cells.

14 avian reovirus isolates adapted to replicate in an African green monkey (Vero) cell line were studied for the nature of their replication. The growth curves of 5 viruses showed them to be highly cell-associated in Vero cells. Different procedures were examined for releasing the cell-associated virus following propagation in Vero cells, including several freeze-thaw cycles, treatment with sterile distilled deionized water (ddH2O), freon extraction, and trypsin treatment. Treatment of virus infected cultures with ddH2O was the most effective, and trypsin treatment was the least effective procedure for dissociation of virus from cells. Treatment of virus infected cultures with ddH2O is a simple and effective procedure which can be used where large amounts of virus are required for experimental purposes.

Animals↗
PubMed1992

The activation antigen CD69 is selectively expressed on CD8+ endomyocardium infiltrating T lymphocytes in human rejecting heart allografts.

We analyzed the presence of T-cell subsets (CD4/CD8) and the activation markers CD25 and CD69 in the cellular infiltrates of endomyocardium biopsies taken from transplanted human hearts. The results indicate that CD25 was present within specimens mainly infiltrated by CD4+ cells. In contrast, CD69 was found in infiltrated biopsies by CD8+ cells, as determined by single immunofluorescence. Double immunoenzymatic staining was used to investigate the cellular distribution of the activation markers studied in some representative cases. Thus, CD25 was found on both CD4+ and CD8+ cells while CD69 molecule was selectively expressed on CD8+ T-cell subset. These results suggest that CD69 is a surface molecule relevant to the CD8+ cell-mediated graft rejection events of allografted human hearts.

Antigens, CD↗
PubMed1992

Epidemiologic observations on porcine cysticercosis in a rural community of Michoacan State, Mexico.

The prevalence of and risk factors for Taenia solium infection (cysticercosis) in pigs were studied in a rural community in Michoacan State, Mexico. Visual inspection of the tongues of 216 pigs revealed cysticerci in 14 (6.5%). The prevalence was slightly higher in male (10/105) than female pigs (4/110) (P = 0.06) and increased with age (P less than 0.05). The most important risk factors for infection in pigs were access to human feces at a public washing area (P = 0.004), the presence of an indoor latrine (P = 0.05) and indiscriminate disposal of human feces around the pig owner's household (P less than 0.1). Effective and long-lasting control of the transmission of T. solium from humans to pigs must include measures to deny pigs access to human feces, a change which is likely to be resisted because of the traditional and functional aspects of established pig-rearing practices.

Age Factors↗
PubMed1992

Recombinant interleukin 4 stimulates human immunodeficiency virus production by infected monocytes and macrophages.

Recombinant interleukin 4 (IL-4) stimulated extracellular (EC) and intracellular (IC) production of human immunodeficiency virus (HIV) from infected human blood-derived monocytes and macrophages when incubated with the cells after but not before virus inoculation. Significant stimulation was observed in 20 of 27 experiments with monocytes (inoculated with HIV immediately after adherence) and 10 of 13 experiments with macrophages (inoculated after 5 days adherence) using a total of 30 normal donors of monocytes and macrophages, and 11 recent isolates of monocytotropic HIV strains (after one passage in mononuclear cells). Marked increases in EC and IC HIV antigen were observed in some experiments, which were comparable with the maximal stimulatory effects of other cytokines such as IL-2. IL-4 also had similar effects on infectious HIV concentration as measured by reverse transcriptase and TCID50 assays. Antibody to IL-4 prevented the stimulatory effect of the cytokine. The proportion of monocytes and macrophages infected by HIV, as determined by in situ hybridization, also increased after incubation with IL-4 for 7 days. The most marked effects were observed with HIV-infected macrophages, for which the proportion of unstimulated infected cells was lower (35 to 45% increasing to 66 to 70% with IL-4 treatment). There was also an increased proportion of cells with high granule concentrations, suggesting that IL-4 increases the intracellular concentration of viral nucleic acids. This was supported by semi-quantitative hybridization experiments showing that total HIV RNA increased in IL-4-stimulated monocytes 48 to 96 h after HIV inoculation. A marked increase in aggregates was observed on day 7 in HIV-infected monocytes treated with IL-4, compared to that in HIV-infected cells alone or IL-4-treated uninfected monocytes. These findings suggest that IL-4 stimulates HIV replication in the early phases of infection and may also facilitate virus transmission by aggregate formation.

Base Sequence↗
PubMed1992

Pulmonary inflammation associated with aspirated meconium and epithelial cells in calves.

"Meconium aspiration syndrome" is a condition resulting in respiratory distress and the occasional death of newborn human beings. A retrospective study was conducted on 52 calves that were submitted for postmortem examination to the Atlantic Veterinary College, Charlottetown, Prince Edward Island, Canada. These calves died of infectious and noninfectious diseases within the first 2 weeks of life due to a variety of causes. The most common cause of death was infectious enteric disease. Histologic examination of lungs revealed that 42.5% of calves had evidence of meconium, squamous cells, or keratin in the lung. There was considerable variation in the magnitude of histologic changes in lungs containing aspirated material. Typically, affected lungs had only a few inconspicuous pieces of meconium, keratin, and squamous cells within bronchoalveolar spaces. Sporadically, the entire lumen of airways was obliterated by aspirated material. Lungs with aspirated material had a mild but diffuse alveolitis characterized by exudation of a few neutrophils, macrophages, and occasional multinucleated giant cells. Obstruction of small airways and focal atelectasis were also observed. Similar lesions have been reported in human meconium aspiration syndrome. It is concluded that histologic changes similar to those of human meconium aspiration syndrome occur commonly in calves that die within 2 weeks of birth. Further studies involving healthy age-matched calves are required to evaluate the clinicopathologic significance of meconium aspiration in this species.

Animals↗
PubMed1992

Hematological parameters are altered during cold air exposure.

Whole blood hematocrit (HCT) decreases during multiple exposures to cold air. To better understand this finding, we have analyzed hematological profiles in 27 normal adult men exposed repeatedly to cold air in one of two experimental protocols. Experiment I was a cold air acclimatization study (CAA) conducted with two groups of 8 men in each group before, during, and after 80 separate 30-minute cold (4 degrees C) air exposures. As part of a metabolic study, half of the men received placebo daily (n = 8), and the other half received an oral daily maintenance dose of the thyroid hormone triiodothyronine (T3) (30 micrograms/day). Blood was analyzed prior to and after every 20 cold exposures. Both groups reacted similarly. When compared with basal conditions, hematocrit (HCT) and erythrocyte counts (RBC) were decreased (p less than 0.05); mean corpuscular hemoglobin concentration (MCHC) and plasma volume (PV) were increased with cold exposure (p less than 0.05). Hemoglobin (Hb), leukocyte counts (WBC), and mean corpuscular volume (MCV) were unchanged. Experiment II was carried out with 9 military volunteers during extended arctic winter field operations (EAO) in Utah and Alaska. Blood was analyzed prior to and after completion of EAO. A changing hematological profile similar to that in the CAA protocol was found. Hematocrit and RBC were decreased (p less than 0.02); MCHC and PV were increased (p less than 0.02). Hemoglobin, WBC, and MCV were unchanged. In addition, there was a negative correlation between HCT and the absolute reticulocyte count in this second experiment. It would appear that in instances of cold stress, whether induced or naturally occurring, certain blood cellular elements respond in a similar adaptive manner.

Acclimatization↗
PubMed1992

Survival and evolution of vein grafts in otosclerosis surgery: structural and ultrastructural evidence.

The annular ligament of the stapes footplate measures 0.2 mm2 and contains elastic fibers that restrict perilymphatic movement to a molecular level. This resistance of the annular ligament prevents excessive movement of labyrinthine fluids that are potentially hazardous to the membranous and cellular structures of the inner ear. However, if the resistance of the annular ligament is overcome, then inner ear damage can occur. The vein graft, as used in our technique for otosclerosis surgery, occupies a space of 0.2 mm2 between the edge of the stapedotomy hole and the piston and has nearly the same compliance and resistance as the annular ligament of the stapes footplate. The vein graft becomes integrated with the middle-ear mucosa. It develops a rich and active blood supply and the smooth muscle cells and elastic fibers remain, although the latter show some modification of ultrastructural pattern. The graft becomes overlaid by the middle-ear epithelium. Even samples of vein graft that have been present for many years retain surviving elastic fibers, including those that have become fibrotic. In time, the number of elastic fibers increases as a result of the activity of fibroblasts, which build a poorly colored collagen.

Adult↗
PubMed1991

Fluorescence properties of methyl 8-(2-anthroyl) octanoate, a solvatochromic lipophilic probe.

Fluorescence excitation and emission spectra, relative fluorescence quantum yield phi r and fluorescence lifetime tau of methyl 8-(2-anthroyl)-octanoate have been studied in a set of organic solvents covering a large scale of polarity and in the presence of water. In this probe, the 2-anthroyl chromophore exhibits quite remarkable and unique fluorescence properties. Thus, when going from n-hexane to methanol, the maximum emission wavelength lambda em max shifts from 404 nm to 492 nm while phi r and tau increase from 1 to 17.7 and from 0.91 ns to 13.5 ns, respectively. These increments are still more accentuated in the presence of water with estimated values of 526 nm for lambda em max, 27 for phi r and 20 ns for tau in this solvent. Because of the presence of a keto group which is a hydrogen bond acceptor and which can conjugate with the aromatic ring so as to provide the chromophore with a high dipole moment, the fluorescence properties of the probe strongly depend on the polarity of the surrounding medium. They can be accounted for in terms of general solvent effects (dipolar solute/solvent interactions) in the presence of aprotic solvents and in terms of specific solvent effects (hydrogen bonding) in protic solvents. Such properties of solvatochromism make the 2-anthroyl chromophore, after 8-(2-anthroyl)octanoic acid has been attached to phospholipids (E. Perochon and J.F. Tocanne (1991) Chem. Phys. Lipids 58, 7-17) a potential tool for studying microenvironmental polarity in biological membranes.

Caprylates↗
PubMed1991

The use of video tape in teaching how psychological factors influence nutritional status in chronic/terminal illness.

The medical students of Louisiana State University Medical School in New Orleans are required to take a clinical nutrition course in their senior year. In 1989, audio-visual media were used to introduce the students to the ways that the psychological aspects of chronic/terminal illness can influence nutritional status. In order to illustrate this topic, a patient with acquired immune deficiency syndrome (AIDS) was interviewed by a psychiatrist, internist, and a dietitian over several weeks. The interviews were videotaped and the videotape was edited to 25 minutes to address specific areas including psychiatric symptomatology, coping with illness, attitude towards treatment, diet and nutritional status, and results of the anthropometric and clinical exams. During the nutrition course, the videotape was presented to the students with subsequent discussion facilitated by the psychiatrist. The students agreed the subject was favorably presented and had increased their understanding of psychological factors in physical illness. The pre- and post-film examinations suggested the students were already aware of many of the psychological issues of chronic/terminal illness. The videotaped interview of a real person diagnosed with a chronic/terminal illness was found to be useful in introducing a difficult subject within a limited course schedule.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Activation of class I HLA expression by TNF-alpha and gamma-interferon is mediated through protein kinase C-dependent pathway in CML cell lines.

The combination of tumour necrosis factor alpha (TNF alpha) and gamma-interferon induced transcription of class I HLA genes in chronic myelogenous leukaemia (CML) cell lines through the formation of a complex between nuclear proteins and the transcriptional enhancers associated with these genes. Although gamma-interferon or TNF-alpha stimulated expression of class I HLA antigens in the EM2 and K562 CML cell lines when used alone, the effect of the combination of TNF-alpha and gamma-interferon was greater than that observed with either agent alone. The induction of class I HLA expression by gamma-interferon and TNF-alpha was inhibited completely by the isoquinoline sulfonamide H7, an inhibitor of protein kinase C. We conclude that the enhancement of the gamma-interferon induced transcriptional activation of class I HLA gene expression by TNF-alpha involves a protein kinase C-dependent pathway.

Base Sequence↗