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Biomedical subjects

A Campos

Publications and source records attributed to A Campos.

At least 181 records · Page 10Linked to original sources
PubMed1990

Scanning electron microscopic study of natural killer cell-mediated cytotoxicity.

The interaction between human natural killer (NK) cells and NK-susceptible target cells, as well as the mechanism involved in target cell lysis, were studied with scanning electron microscopy (SEM). Low density human peripheral blood lymphocytes, highly enriched with large granular lymphocytes (LGL), were used as effector cells, and K562-cells were used as NK-susceptible target cells. The surface features of LGL/NK cells were examined under SEM. In the area of interaction, NK/target-cell conjugates showed microvilli and/or filipodia, and extensive areas of intercellular contact. In addition, the effector cells in some NK/target-cell conjugates were polarized toward the target cell. Changes in target cell surface features included loss of microvilli, large surface blebs and the appearance of small pore-like lesions on the cell membrane. Our findings show that target cell lysis occurred by apoptosis and plasma membrane lesions analogous to those seen during complement-mediated cytotoxicity.

Cytotoxicity, Immunologic↗
PubMed1989

X-ray microanalytical histochemistry of human circumpulpar and mantle dentine.

An X-ray microanalytical histochemistry study was carried out, on thick sections observed under scanning electron microscopy, of five freshly extracted human premolars and five molars. In particular the circumpulpar and mantle dentine were examined to determine levels of calcium, phosphorus and sulphur, the basic elements involved in the process of biomineralization. Semiquantitative analysis was subsequently performed after the appropriate ZAF (Z, atomic number; A, absorption; F, secondary fluorescence) correction. Ca/P mass ratio was found to be similar for both regions in molars and slightly higher in circumpulpar dentine in premolars implying that this parameter is independent of the processes of biomineralization in the two dentinal regions. In contrast, statistically significant differences were recorded in sulphur content upon comparing mantle and circumpulpar dentine between premolars and molars (P less than 0.02). If sulphur, which has been associated with sulphated glycosaminoglycans (GAGs) decreases as mineralization progresses it would therefore seem reasonable to posit sulphur-rich areas in both topographical regions of the matrix--more significant in premolars than molars--able to undergo subsequent mineralization if required. The possible application of these findings in remineralization therapies is suggested.

Bicuspid↗
PubMed1989

[Histological study of idiopathic gingival melanosis].

Idiopathic gingival melanosis was studied from a histological viewpoint. Structural data obtained with light, transmission and scanning electron microscopy were correlated. Marked pigmentation, of the epithelium, fundamentally in basal strata, was observed. Scanning electron microscopy revealed three different cellular patterns, distinguishable on the basis of the surface configuration of the apical membrane.

Epithelium↗
PubMed1989

[Peritoneal hydatidosis with fistulization into the sigmoid colon].

A case is presented of peritoneal hydatidosis with fistulization into the sigmoid in a patient who had previously undergone surgery for hepatic hydatidosis. The clinical picture made its debut as an alteration in intestinal habit followed by the appearance of diarrheic syndrome and expulsion of hydatid membranes. The natural history of peritoneal hydatidosis, its complications and therapeutic guidelines are discussed.

Aged↗
PubMed1988

Carcinoma developing in ileostomies after 25 or more years.

Primary carcinoma of the ileal mucosa in patients who have had an ileostomy has been documented rarely. This report describes 4 patients seen within the last 4 yr with ileal carcinoma adjacent to the mucocutaneous junction of an ileostomy 25, 29, 30, and 34 yr after the stoma was formed. The incidence of this serious complication may be increasing.

Adenocarcinoma↗
PubMed1988

Analysis of the binding of Ca2+ to gramicidin A in ethanol in terms of the dimer-monomer conformational equilibrium.

This study reports the first direct observation of the binding of Ca2+ to gramicidin A in ethanol, analysed in terms of the polypeptide dimer-monomer conformational equilibrium. High performance size-exclusion chromatography has been successfully used to elucidate the binding mechanism and to determine the rate constants as well as the stoichiometry of the processes involved. In addition, fluorescence intensity and anisotropy measurements have revealed a dependence of the number of accessible Ca2+-binding sites on the peptide concentration.

Calcium↗
PubMed1988

Determination of flunarizine in plasma by a new high-performance liquid chromatography method. Application to a bioavailability study in the rat.

A reversed-phase high performance liquid chromatographic (HPLC) method is described for the study of the pharmacokinetics of flunarizine. The method involves selective liquid-solid extraction of flunarizine and meclizine (as internal standard) from samples of rat plasma. The optimization of the extraction and HPLC separation parameters are discussed. Recoveries were satisfactory and the relative standard deviation for replicate assays was below 10%. The sensitivity of the method would allow the detection of flunarizine in plasma at 13 ng ml(-1). Kinetic parameters for a bioequivalency study between flunarizine and a liquid formulation (oral drops) have been evaluated; the relative bioavailability was 88%.

Journal Article↗
PubMed1988

Determination of a buspirone metabolite in plasma samples.

A high-performance liquid chromatographic (HPLC) method is described for the assay of the active metabolite [1-(2-pyrimidinyl)piperazinel of buspirone, an anxiolytic agent, in rat plasma. The method is based on the use of ion-pair HPLC coupled to a liquid-solid extraction scheme. Samples of rat plasma (2 ml) with internal standard (1-phenylpiperazine), adjusted to pH 10.5 with borate buffer, were loaded on to a preactivated C-18 cartridge. The metabolite and the internal standard were eluted with 5 ml of methanol and injected on to a reversed-phase 10-microm Spherisorb ODS-2 column. The column was eluted with a mobile phase of 0.005 M sodium lauryl sulphate in citrate buffer (pH 3.6)-acetonitrile (65:35, v/v) at 2 ml min(-1). Detection was carried out at 248 nm. The recovery of the metabolite was 55%. The method was applied to the determination of the metabolite in rat plasma after oral dosing (25 mg kg(-1)) of the parent compound.

Journal Article↗
PubMed1988

Visual Elaboration Scale as a measure of imagery.

We studied the correlation of one measure of imagery ability, the Visual Elaboration Scale, with two others, absorption of image and effort required to form a mental image. Significant correlations were obtained between the Visual Elaboration Scale and the other scales, with the exception of Absorption for women.

Adolescent↗
PubMed1988

Vividness of imagery and positive and negative values of emotionality of words.

We estimated the correlations of scores on vividness of imagery of 122 undergraduates using Mark's imagery questionnaire with positive and negative emotionality values of words. We also studied the influence of imagery vividness (good and poor imagers) in emotionality. Analysis indicates a significant correlation for the 52 men and for the total group between imagery vividness and emotionality. The good imagers gave higher emotionality scores than poor imagers.

Adolescent↗
PubMed1987

Grave anaphylactic-like reaction in the course of menstruation. A case report.

The case of a woman with a serious anaphylactic pattern during menstruation is described. The patient had a clinical picture of urticaria, angioedema and shock at each menstruation for a period of 2 years until hysterectomy was performed. The studies showed no hormonal or immunological change. The only relevant finding was the extraordinarily strong vasodilating action of the menstrual fluid in the patient, and not in the controls. The results of the study suggest the possibility of two mechanisms: 1) an IgE-mediated mechanism causing hypersensitivity to some metabolic substance in the menstrual fluid and 2) an excessive pharmacological vasodilatory action produced by the prostacyclin in the fluid itself.

Adult↗