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Biomedical subjects

A Lopez

Publications and source records attributed to A Lopez.

At least 235 records · Page 13Linked to original sources
PubMed1988

Identification and characterization of a human cell line with dendritic cell features.

CORP-4 is a cell line obtained in our laboratory from an explanted human bladder carcinoma. This cell line shows certain dendritic cell features such as adherence to the culture plate surface, a doubling time of 24 h and an enzymatic profile typical of cells involved in antigen presentation (non-specific esterases, lysozyme and alpha-1-antitrypsin). Its phenotypic analysis revealed CD 15 and Fc receptor expression, S-100 surface protein and the presence of positive reactivity to different lectins such as Concanavalin A (Con A) and Peanut agglutinin (PNA). CORP-4 was found to be a non-phagocytic cell line after it was assayed with latex, and FcR- and C3bR-mediated phagocytosis. Furthermore, CORP-4 produced interleukin-1 (IL-1) as determined by thymocyte proliferation assays and also fixes immune complexes in a non-complement dependent fashion. HLA class I and class II antigens were inducible by both 5 azacytidine and gamma interferon.

Agglutination Tests↗
PubMed1988

Application of fluorine-19 nuclear magnetic resonance to the determination of plasma-protein binding of 5'-deoxy-5-fluorouridine, a new antineoplastic fluoropyrimidine.

Two distinct fluorine-19 nuclear magnetic resonance ((19)F NMR) signals have been observed in human serum for free and plasma-protein bound 5'-deoxy-5-fluorouridine (5'dFUrd). The binding of this drug was studied directly in serum using (19)F NMR. To evaluate the validity of this method, a parallel study was conducted with equilibrium dialysis as the reference method. Two assay methods were applied after equilibrium dialysis, UV spectrophotometry and (19)F NMR spectrometry, the UV assay being used to validate the (19)F NMR assay. A study of the binding of 5'dFUrd to human serum albumin was also reported. The reliability of (19)F NMR as a technique to measure directly the binding of the drug and as an assay after equilibrium dialysis was demonstrated. The percentage of 5'dFUrd bound to plasma proteins is low and concentration-dependent in the 0.04-3.5 mmol l(-1) range.

Journal Article↗
PubMed1988

Fluorescence recovery after photobleaching (FRAP) experiments under conditions of uniform disk illumination. Critical comparison of analytical solutions, and a new mathematical method for calculation of diffusion coefficient D.

A simple fluorescence recovery after photobleaching (FRAP) apparatus using a fluorescence microscope with a conventional mercury arc lamp, working under conditions of "uniform disk illumination" is described. This set-up was designed essentially for the use of anthracene as fluorescent probe, which is bleached (photodimerization reaction) by illumination in the near ultraviolet range (360 nm). It is shown that the lateral diffusion coefficients D can be readily calculated from fluorescence recovery curves using a finite differentiate method in combination with statistical analysis of the data. In contrast to the analytical solutions so far described, this numerical approach is particularly versatile. With a minimization algorithm, D and the probe mobile fraction can be readily calculated for any recovery time under various experimental conditions. These include different probe concentration profiles in the illuminated area after the bleaching step, and situations of infinite or noninfinite reservoir in the diffusion area outside the illuminated area.

Diffusion↗
PubMed1988

Use of sulfur hexafluoride and a three-dimensional sampling grid for evaluation of inhalation chamber performance.

Knowledge of the distribution of a toxic agent, for example, hydrogen sulfide, within an exposure chamber is essential for satisfactory inhalation toxicology studies. The use of a three-dimensional sampling grid is described for sampling inhalation chamber atmospheres containing various concentrations of sulfur hexafluoride gas as a substitute for the more toxic hydrogen sulfide.

Air↗
PubMed1988

Risk factors for early occurring pressure ulcers following spinal cord injury.

We carried out a prospective study to determine the association between immobilization in the immediate postinjury period and the development of pressure ulcers in spinal cord-injured patients following their admission to Charity Hospital, New Orleans. Of 39 patients consecutively admitted to the hospital, 23 (59%) developed a grade one ulcer within 30 days, mostly in the sacral region (57%), the peak time of onset being day 4 postinjury (6/23 cases). In partial support of an earlier retrospective study (Linares HA, Mawson AR, Suarez E, Biundo JJ Jr: Association between pressure sores and immobilization in the immediate post-injury period. Orthopedics 1987;10:571-573), duration of unrelieved pressure prior to ward admission was significantly associated with ulcers developing within the first eight days of injury (P = 0.04), but not with ulcers developing during the entire 30-day observation period (P = 0.09). Time on the spinal board was also significantly associated with ulcers developing within 8 days (P = 0.01), but not with ulcers developing within 30 days (P = 0.09). An unexpected finding was the significant inverse association between systolic blood pressure and the development of ulcers both within 8 days (P = 0.03) and within 30 days (P = 0.02), suggesting that reduced tissue perfusion increases the spinal cord-injured patient's susceptibility to pressure ulcers.

Adolescent↗
PubMed1988

Histologic and ultrastructural alterations in lungs of rats exposed to sub-lethal concentrations of hydrogen sulfide.

Fischer-344 rats were killed 1, 18, and 42 hr after a single 4-hr exposure to an atmosphere of 0, 116, or 615 mg m-3 of hydrogen sulfide (H2S). Lungs, fixed by the intratracheal route, were examined by light and electron microscopy. Histologic changes were transient and mainly present in rats exposed to 615 mg m-3 H2S. Lesions included severe but transitory pulmonary edema and fibrinocellular alveolitis which was restricted to the proximal alveolar region of the lung. Electron microscopically, ciliated bronchiolar cells were the only cells that developed necrosis; they were rapidly replaced by mitosis. Alveolar endothelium had cytoplasmic blebs, but alveolar epithelium had minor changes. No mast cell degranulation was detected in lungs with edema. A 4-hr exposure to 615 mg m-3 is markedly edematogenic for the lung but only moderately cytotoxic for pulmonary cells.

Animals↗
PubMed1988

Similarities in hypothalamic-pituitary-adrenal axis activity between patients with panic disorder and those experiencing external stress.

Psychologic stressors are less potent stimuli of the HPA axis in humans than physical stressors, but they can cause mild changes in acute ACTH and cortisol production. These changes, however, are generally not of sufficient magnitude or duration to cause measurable changes in UFC excretion. Furthermore, chronic stress leads to an attenuation of the HPA axis response. This basic knowledge concerning psychologic stress helps explain the reason why patients with uncomplicated anxiety/panic disorder, a condition involving similar symptoms, do not demonstrate UFC abnormalities. Panic disorder, when accompanied by depression, however, is associated with an increase in UFC excretion which is probably more related to the depression than the panic state. Interestingly, panic disorder, when accompanied by agoraphobia, also shows an elevation in UFC levels which makes it endocrinologically distinct from uncomplicated panic disorder. The reason for this is unclear. Treatment of the panic disorder with benzodiazepines does not further lower the UFC levels in patients with uncomplicated panic disorder despite clinical improvement, but it does lower UFC levels into the normal range in those with concurrent depression and agoraphobia. Alteration in the UFC level with treatment is only partially related to clinical improvement.

Agoraphobia↗
PubMed1988

Concentration-time interactions in hydrogen sulphide toxicity in rats.

Concentration-time interactions were investigated in young male and female Sprague-Dawley, Long Evans and Fischer-344 rats exposed to hydrogen sulphide for two, four or six hours. Higher concentrations caused more deaths, with no significant difference for duration of exposure. A significant sex effect was noted with 30% mortality in males and 20% in females, with no significant difference among strains. Changes in weight were significant: increasing with concentration, higher in males than in females, different among strains (Fischer-344 less than Sprague Dawley less than Long Evans), and affected by duration of exposure. Lethal concentration values (LC50 and LC10) were estimated, for the pooled data set (n = 456); the probit equation was Y = -5.74749 + 3.8259X where X is log10 dose of hydrogen sulphide in parts per million. The LC50/LC10 values were 644/298 parts per million (902/417 mg m-3) respectively. Individual probit analyses were also performed for strain, hours of exposure and sex. The LC50 and LC10 values for male, female and strain were not different. Significant differences were observed among LC50/LC10 values for hours of exposure (2 h = 587/549 parts per million, 822/769 mg m-3; 4 h = 501/422 parts per million, 701/591 mg m-3; 6 h = 335/299 parts per million, 469/491 mg m-3). There was no effect of spatial position in the exposure chamber on the distribution of mortality. All rats of all strains dying had severe pulmonary edema.

Analysis of Variance↗
PubMed1988

Nasal lesions in rats exposed to hydrogen sulfide for four hours.

Fischer-344 rats were exposed for 4 hours to 0, 14, 280, or 560 mg of hydrogen sulfide.m-3 and killed 1, 18, or 44 hours later. We evaluated the nasal epithelial cells and determined the anatomic distribution of lesions. Inhalation of 560 mg of hydrogen sulfide.m-3 induced necrosis and exfoliation of respiratory and olfactory mucosal cells, but not squamous epithelial cells. The anatomic distribution of lesions was midway along the nasal passages involving nasal and maxillary conchae, but not ethmoidal conchae. Injured respiratory mucosa repaired rapidly, whereas olfactory mucosa continued to exfoliate at 44 hours after exposure.

Animals↗
PubMed1987

Two new icosapentaenoic acids from the temperate red seaweed Ptilota filicina J. Agardh.

Two new fatty acid metabolites, 5(Z),7(E),9(E),14(Z),17(Z)-icosapentaenoic acid and 5(E),7(E),9(E),14(Z),17(Z)-icosapentaenoic acid, have been isolated from the temperate red marine alga, Ptilota filicina (Ceramiales, Rhodophyta). The structures of these new compounds, isolated as their methyl ester derivatives, have been deduced from detailed 1H nuclear magnetic resonance (NMR), 13C NMR and 2D-NMR analyses as well as comparisons to known compounds.

Eicosapentaenoic Acid↗
PubMed1987

Alterations in lateral lipid mobility in the plasma membrane of urodelean ectodermal cells during gastrulation.

The mobility characteristics of lipids were studied in the plasmalemma of dissociated presumptive ectodermal cells from embryos of Pleurodeles Waltl at different stages of development, from early blastula to early neurula, using a Fluorescence Recovery After Photobleaching technique (FRAP), after incorporation of the lipophilic fluorescent probe 5N-(hexadecanoyl)-aminofluoresceine (HEDAF) into the cell plasma membrane. At all stages of development, fluorescence recovery was found to extrapolate to 100%, which suggested that the lipid phase in these plasma membranes can be regarded as dynamically homogeneous (no immobilized fraction). It appears as a continuum over a wide cell surface area, in which lipids are free to move laterally. The lateral diffusion coefficient of the probe, obtained from statistical analysis of the fluorescence recovery data, was found to decrease significantly from blastula to gastrula, slightly increasing at the neurula stage. These changes in the dynamic properties of the lipid probe HEDAF during gastrulation suggest that the lipid phase of the plasma membrane of these ectodermal cells undergo structural changes. The results lend support to the idea that the plasma membrane of these cells is actively involved in the morphogenetic movements which characterize the development of the embryo.

Animals↗