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M Arias

Publications and source records attributed to M Arias.

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

Comparison of two antigens for use in an enzyme-linked immunosorbent assay to detect African swine fever antibody.

Two African swine fever virus (ASFV) antigens were tested for use in an ELISA to detect antibody to ASFV. Antigens used were the cytoplasmic soluble fraction (CS-P) of infected cells grown in the presence of porcine serum and the semipurified viral structural protein VP73 (SVP73). Both antigens were tested by ELISA against 72 sera obtained during several ASF field episodes and from ASFV-inapparent carriers. Of the 72 sera, only 2.8% has positive results by ELISA against CS-P antigen; 60% of positive-reacting sera (to both antigens) had higher ELISA values when the CS-P antigen was used. Samples (with positive results) that reacted only to CS-P antigen had results confirmed by immunoblot analysis. Such sera reacted against ASFV-infection proteins IP25, IP25.5, and IP30, but not against IP73. In time-course experiments to detect appearance of ASFV-antibodies in infected miniature pigs, antibodies were detected by immunoblot analysis on postinoculation day (PID) 8. At that time, only the polypeptides IP25, IP25.5 IP30, and IP31 were recognized; IP73 and IP12 were first detected 3 and 4 days later, respectively. In the same experiments, ASFV antibodies were detected by ELISA, using CS-P or SVP73 antigens, on PID 7 and 9, respectively. These results could explain the percentage of sera not having positive results by ELISA using SVP73 antigen, if the sera were obtained from ASFV-infected pigs during the first days of infection before induction of antibody response against the IP73 protein. This feature makes the use of CS-P antigen advantageous in early serologic detection of ASFV-infected pigs.

African Swine Fever Virus↗
PubMed1989

Involvement of the lysine-binding sites of plasminogen on its interaction with concanavalin A.

Two different interactions are involved in the binding of plasminogen to concanavalin A-Sepharose: both variants 1 and 2 interact with the lectin through the lysine-binding sites and, in addition, variant 1 binds to concanavalin A due to carbohydrate recognition. Both kinds of interactions were also observed in solution by analytical ultracentrifugation. The binding of Lys-plasminogen to concanavalin A via lysine-binding sites largely exceeds that of Glu-plasminogen, in accordance with the higher affinity for lysine of Lys-plasminogen. This fact can be applied to the separation of both forms of plasminogen in a single chromatographic step.

Binding Sites↗
PubMed1989

Fractionation of plasmic fibrin(ogen) digests by lectin affinity chromatography.

A method for the fractionation of plasmic digests of both fibrinogen and fibrin was developed by taking advantage of the different chromatographic behaviour of fibrinogen and its fragments on immobilized concanavalin A and Lens culinaris agglutinin. Columns with different lectin concentration but with the same total lectin content were tested. Fragment E was retained on all the concanavalin A-Sepharose preparations while fragment D was mostly eluted in the unbound fraction. However, the binding of fragment DD depended on the lectin concentration of the gel. Thus, the percentage of fragment DD specifically bound to concanavalin A-Sepharose increased from 5-10% to 67% as the lectin density of the gel increased from 0.9 to 8.7 mg/ml gel. On the other hand, Lens culinaris agglutinin-Sepharose retained fibrinogen and high molecular weight fragments depending on the lectin concentration of the gel while neither fragment E nor fragment D were bound to any of the columns.

Carbohydrate Conformation↗
PubMed1989

Hyperparathyroidism is responsible for the increased levels of osteocalcin in patients with normally functioning kidney grafts.

Osteocalcin or bone Gla protein (BGP) is the most abundant noncollagenous protein of the skeleton. Serum BGP levels are thought to provide a valuable index of bone formation. We measured serum BGP and other parameters of mineral metabolism in 68 patients with functioning kidney grafts. The duration of the graft ranged from 1 to 131 months (mean 23). Serum BGP was positively correlated with parathyroid hormone (r = 0.56, p less than 0.001). BGP was inversely correlated with glomerular filtration rate (r = -0.44, p less than 0.001) and with the total cumulative dose of corticosteroids received after transplantation (r = -0.26, p less than 0.05). No correlation was observed between BGP and 1,25(OH)2D, nor between BGP and serum aluminum. All patients with increased BGP in the presence of normal renal function had persistent hyperparathyroidism. The activity of the parathyroid glands and corticosteroid treatment seem to be the main pathophysiological factors influencing BGP levels after successful kidney grafting.

Adult↗
PubMed1988

Serum levels of 1,25-dihydroxyvitamin D after renal transplantation.

Serum levels of vitamin D metabolites have been studied in 68 patients 1-131 months (mean 23 +/- 23) after kidney transplantation. They were separated into two groups according to the duration of the graft. Patients with a graft duration longer than 6 months had a mean GFR of 73 +/- 36 ml/min. Their serum levels of 25-hydroxyvitamin D (25-OHD) were normal (15.9 +/- 8.4 ng/ml), while serum levels of 1,25-dihydroxyvitamin D (1,25-OHD) were reduced (28 +/- 11 pg/ml). A highly significant correlation between GFR and 1,25-OHD was observed (r = 0.58; p less than 0.001). Most patients with normal renal function had levels of 1,25-OHD in the normal range, but they frequently remained slightly lower than those of healthy controls (33 +/- 9 vs. 38 +/- 10 pg/ml; p = 0.05), albeit the presence of elevated PTH and/or hypophosphatemia. In some patients, a low supply of 25-OHD could impair the normalization of 1,25-OHD levels. No clear differences in vitamin D metabolites were observed between patients transplanted 1-6 months ago and those with a longer duration of the graft. Nevertheless, serum 25-OHD showed a tendency to increase with time. These results indicate that, although 1,25-OHD levels may not be fully normalized, successful kidney transplantation restores the ability to effectively metabolize vitamin D.

Adolescent↗
PubMed1987

Ultrastructural analysis of chick embryo blastoderms explanted in vitro in absence of endoderm. Differentiation capacity of mesoderm.

A study of the structural characteristics of stage 5 chick embryo blastoderms, cultured in vitro, was carried out after previous elimination of endoderm to analyse the differentiation capacity of mesoderm. Our results show that only the precardiac mesoderm is determined at this early stage and that it is able to differentiate cardiac tissue in the absence of the endoderm. The ultrastructural characteristics of this tissue are described. However, the degree of differentiation of cardiomyoblasts does not reach the expected level of organization and myofibrillar complexity.

Animals↗
PubMed1987

Hypertension after renal transplantation. A comparison of cyclosporine and conventional immunosuppression.

Hypertension is a common complication after renal transplantation and is associated with increased mortality. Cyclosporine is known to be nephrotoxic and raises blood pressure in recipients of cardiac and bone marrow transplants, but there is conflicting data on the role of cyclosporine after renal transplantation. We have examined this question in patients entered into the second Oxford prospective randomized comparison of short-term cyclosporine treatment alone with conversion to azathioprine and prednisolone at 90 days (CsA group), and conventional therapy with azathioprine and prednisolone throughout (AP group). Blood pressure and antihypertensive medication were similar in the CsA and AP treatment groups during the first 90 days. Following conversion from cyclosporine, mean blood pressure fell from 155/94 to 142/81 within 7 days, and this fall correlated with the change in plasma creatinine over the same period (r = 0.44, P less than 0.05). Blood pressure was subsequently lower in the converted patients than in those treated with AP throughout. Six months after transplantation patients converted from cyclosporine not only had lower blood pressure but also required fewer antihypertensive drugs than AP patients. This study demonstrates that cyclosporine may elevate the blood pressure in recipients of renal transplants. This effect may either be direct or mediated through the effect of cyclosporine on renal function. Administration of corticosteroids during the first three months after transplantation is implicated as a possible cause of persisting high blood pressure.

Adult↗