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Biomedical subjects

A Mosca

Publications and source records attributed to A Mosca.

At least 73 records · Page 4Linked to original sources
PubMed1992

IHP entrapment into human erythrocytes: comparison between hypotonic dialysis and DMSO osmotic pulse.

Three different blood units were treated separately by the hypotonic dialysis (HD) and the dimethylsulphoxide osmotic pulse (DMSO) method, in order to load the erythrocytes with inositol hexaphosphate. A detailed comparison between the two loading techniques was performed by monitoring the red cell distribution patterns on discontinuous Percoll density gradients, the RBC oxygen affinity and the amount of the main intracellular organic phosphates with the 31P-NMR. The results obtained showed that: (1) The HD loading produces a redistribution of the RBC fractions with a concomitant smoothing of the relative differences among distinct fractions (2) only a minor portion of erythrocytes (from 8.5 to 24.9% of total RBCs) are loaded with IHP after the DMSO treatment. All of these cells move to the lightest fraction (d = 1.080 g/ml). (3) Both HD and DMSO IHP-loaded cells show an increase in P50 (basal vs. after loading, means +/- SD: 25.8 +/- 3.0 vs. 52.5 +/- 3.2 mm Hg) correlated to the IHP incorporation (mean intracellular IHP concentration: 4.2 mmol/l RBC). (4) probably the IHP incorporation efficiency could be probably improved at least by increasing the IHP concentration during the treatment.

Dialysis↗
PubMed1992

Nonradioactive quantification of low concentrations of hemoglobin A by HPLC for midtrimester prenatal diagnosis of beta-thalassemia.

The usual methods for prenatal diagnosis of beta-thalassemia and other hemoglobinopathies by assay of fetal blood erythrocytes are either complex (analysis of globin chains synthesis by carboxymethylcellulose chromatography) or only semiquantitative [isoelectric focusing of hemoglobin (Hb)]. To further simplify the diagnostic procedure and to obtain quantitative data, we measured the small concentrations of Hb A in fetal erythrocytes by using a high-pressure liquid chromatography (HPLC) instrument (DIAMAT-TM; Bio-Rad) equipped with the new column proposed for measuring Hb A2. We analyzed 212 uncontaminated fetal blood samples obtained by cordocentesis between the 18th and 22nd weeks of pregnancy, using the HPLC procedure, and compared the results with those obtained by the above-named methods. The Hb A values obtained ranged between 0% and 8.5%; they were less than or equal to 1.8% in 44 fetuses affected by homozygous beta-thalassemia and greater than 2.5% in 168 unaffected fetuses. The method was simple, rapid, and reproducible (CV 3.2%) and there was good correlation between Hb A concentrations determined by HPLC and the beta/gamma ratio determined by carboxymethylcellulose chromatography (r = 0.7687; P less than 0.0001). No false-negative or false-positive results were observed, and there was no overlap of values between affected and unaffected fetuses.

Chromatography, High Pressure Liquid↗
PubMed1991

Clinical utility of fractionating erythrocytes into "Percoll" density gradients.

Two rapid methods for fractionating the RBC into five or nine layers of increasing density are reported. These procedures have been used to monitor the decline of glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) activity during the process of red cell aging in normal subjects and in beta-thal carriers, to study transfused patients with G6PD and pyruvate kinase (PK) deficiency and to test the effects of inositol hexaphosphate (IHP) encapsulation on RBC subpopulations.

Adult↗
PubMed1989

Different priming on human neutrophil respiratory burst by lipopolysaccharides from phase I and phase II Coxiella burnetii.

Human neutrophils produce small amounts of superoxide anion when stimulated with the chemotactic peptide FMLP; preincubating neutrophils with low concentrations of lipopolysaccharides (LPS) markedly increases this response, an effect referred to as priming. In this work LPS from Coxiella burnetii either phase I (virulent) or phase II (avirulent) were examined for their ability to induce priming. Results clearly show that only LPS from phase II microorganism was able to increase the release from neutrophils upon subsequent stimulation with FMLP. This effect was abolished by preincubation of LPS with polymyxin B. This finding may account for the ability of Coxiella burnetii phase I to escape intracellular phagocyte killing during persistent infections.

Coxiella↗
PubMed1989

Chromatofocusing and isoelectric focusing in immobilized pH gradients compared for characterization of human hemoglobin variants.

We compared the performance of two highly resolving methods, chromatofocusing (CRF) and isoelectric focusing in immobilized pH gradients (IPGF), for the separation of human hemoglobin variants. Lysates containing 13 different hemoglobins, including variants of clinical and geographical importance, and four electrophoretically "silent" variants (Hb Brockton, Hb Cheverly, Hb Köln, and Hb Waco) were analyzed. Both techniques showed a good intrarun precision (CV = 0.87% for CRF, 0.27% for IPGF) and high and similar resolving power (0.010 pH units, with the pH gradients used in this work). The use of an ultranarrow IPGF range (pH 7.15-7.35; pH gradient = 0.019 pH/cm) allowed the resolution between Hb Brockton, Hb Köln, and Hb A. In some cases (Hb D-Los Angeles, Hb F, Hb Waco), the variants were separated from Hb A in different orders, depending on which technique was used, probably because of the different analytical principles of the two methods. As a second-level test, both procedures are informative for characterization of human hemoglobin variants.

Chromatography↗
PubMed1987

Possible role of plasminogen activator content of the palmar nodules in recurrence of Dupuytren's contracture.

Increased amounts of plasminogen activator enzymes were found in the large Dupuytren's nodules in the so-called active phase of the disease. A prospective study in 15 patients who had operations investigated possible relationships between fibrinolytic capacity of the palmar nodules (assessed by the fibrin plate method) and the recurrence of contracture. There were substantial analogies and suggestive connections with the results of previous electron microscopic studies. Combined with the presence of myofibroblasts, the high increase of plasminogen activator enzymes in the fascial nodules may be regarded as a predictive marker for possible recurrence after surgical treatment of Dupuytren's contracture.

Adult↗
PubMed1987

Glycated proteins in serum: effect of their relative proportions on their alkaline reducing activity in the fructosamine test.

The fructosamine test is considered clinically useful for assessing short-term integrated control of blood glucose, but there are few published data to support this hypothesis. We fractionated glycated and nonglycated proteins by affinity chromatography on phenylboronate columns and, with specific immunochemical methods, determined in the eluted fractions the following proteins, selected according to their biological half-lives and relative concentrations in serum: albumin, IgA, IgG, IgM, apolipoprotein B, haptoglobin, transferrin, alpha 1-antitrypsin, and alpha 2-macroglobulin. We found the following correlations between fructosamine (mmol/L) and, respectively, glycated albumin, IgG, and (albumin + IgG) (each in grams per liter): r = 0.901, 0.702, 0.878. IgM had the highest percentage of glycated molecules (range 11.1-37.5%, mean 22.4%), haptoglobin and alpha 1-antitrypsin the least. This result was almost independent of the proteins' molecular masses and fractional catabolic rate. Albumin evidently contributes most to results of the fructosamine test, confirming conclusions obtained in different ways by others.

Apolipoproteins B↗
PubMed1987

Use of chlamydiazyme for the detection of Chlamydia trachomatis in genital infections.

48 endocervical specimens from women with cervicitis and 82 urethral specimens from men with urethritis were investigated for the presence of Chlamydia trachomatis by either the cell culture method or enzyme immunoassay (Chlamydiazyme, Abbott Laboratories). The overall sensitivity and specificity of Chlamydiazyme assay were 84.6% and 95.2% respectively. This study shows that Chlamydiazyme assay is a quite sensitive and specific tool for a rapid and simple detection of chlamydial antigens in genital samples.

Antigens, Bacterial↗
PubMed1987

Urea determination in dialysis, based on a differential pH technique.

The application of a new technique, based on differential measurements of pH, to determine urea concentration in patients of a dialysis center, is reported. Urea in plasma, whole blood or dialysis fluids is measured by an enzymatic reaction, with urease; the procedure, requiring 10 microL of sample, is simple, fast and correlates well with a reference spectrophotometric method, in the 0-300 mg/dL concentration range, according to the equation y = 1.0291 X -0.0777; r = 0.9991; n = 73.

Autoanalysis↗
PubMed1987

Plasma protein glycation as measured by fructosamine assay.

The fructosamine test for assessing control of glucose in blood has been extensively evaluated, but some questions remain regarding its validity. From the analytical and clinical evaluation we present here, we conclude that: the test is sensitive to variations in the composition of the sample protein; the fructosamine reaction is almost completely unaffected by labile fractions; the concentrations of fructosamine correlate well with the degree of glycation of total serum proteins, especially with glycated albumins and glycated immunoglobulins, as determined by affinity chromatography; the correlation with glycated hemoglobin (Hb A1c), measured as the stable fraction, is very poor, in diabetics treated with insulin (r = 0.373), or with oral hypoglycemic agents (r = 0.390); and (e) fructosamine and Hb A1c are, in fact, expressions of different periods of metabolic control and therefore have different clinical meanings.

Adolescent↗
PubMed1987

Ethylene glycol-stabilized haemolysates for glycated haemoglobin assay. Further analytical investigations and applications to quality control programmes.

The direct effect of the ethylene glycol on the quantitation of glycated haemoglobins by ion-exchange minicolumn chromatography, affinity chromatography and high performance liquid chromatography was investigated. No evident effect was found for ethylene glycol concentrations between 0.0 and 0.5 (volume fraction). The ethylene glycol-stabilised haemolysates were also analysed by HPLC: the elution profiles were similar to those of haemolysates fresly prepared from whole blood, and they remained unchanged, even after 18 months of storage at -20 degrees C. A preliminary inter-laboratory trial among 15 Italian laboratories was organized, using these ethylene glycol-stabilised haemolysates and, for comparison, a lyophilized commercial preparation. From the data obtained in this trial we confirmed the validity of using ethylene glycol-stabilized haemolysates as control materials, both for intra- and inter-laboratory standardization of glycated haemoglobin measurements.

Chromatography, Affinity↗
PubMed1986

Adenosine induced production of a soluble factor affecting lymphocyte activation.

We show that a brief exposure of human peripheral blood mononuclear cells (PBMC) to adenosine or to theophylline results in a mitomycin C resistant regulatory activity. Adenosine induced suppression is also detectable in a lymphocyte subpopulation (T4+ enriched, originally described as helper inducer) resistant to the theophylline induced loss of capacity to form spontaneous rosettes with sheep erythrocytes (TTR). This activity is apparently dependent on the production of a soluble factor(s) since supernatants from adenosine treated TTR (SnA) exert a significant inhibition on the proliferative response of resting lymphocytes. On the contrary SnA increases the concanavalin A (ConA) preactivated lymphocytes proliferation. Similar results are detectable on the proliferative response in the mixed lymphocyte reaction (MLR). Perhaps these effects are related to different Interleukin 2 (Il 2) receptor expression on the cell surface of the resting and preactivated populations. A slow moving band corresponding to a protein of Mr of 64,500 and isoelectric point 7.6 is present in SnA. Only a slight Il 2 activity is detectable either in SnA and in control supernatant (SnC). These findings suggest that SnA may be a dynamic regulator of the early stages of lymphocyte activation.

Adenosine↗