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Biomedical subjects

J Prieto

Publications and source records attributed to J Prieto.

At least 307 records · Page 17Linked to original sources
PubMed1989

MALA-2, mouse homologue of human adhesion molecule ICAM-1 (CD54).

In humans, lymphocyte adhesion to cells is mediated by the protein heterodimer CD11a/CD18 (Leu-CAMa, LFA-1) and its ligand CD54 (ICAM-1). Although the murine CD11a/CD18 is well characterized, the mouse homologue of human ICAM-1 has not been identified. In the present study a rat monoclonal antibody to the murine lymphocyte activation antigen MALA-2 was found to inhibit in a dose-dependent manner the phorbol ester-enhanced aggregation of mouse lymphoblasts, an adhesion-specific assay, and hence to define an adhesion molecule. By immunofluorescence flow cytometry the antigen expression was low on spleen cells but it largely increased after stimulation with mitogens. The antigen was expressed by some, but not all, lymphoid cell lines, and myelomonocytic and mastocytoma cells were also positive. In frozen tissue sections MALA-2 was mainly detected on germinal center B cells, dendritic cells, macrophages and vascular endothelium, including high endothelial venules. Cell surface labeling followed by immunoprecipitation and gel electrophoresis indicated that the antigen is a sialoglycoprotein which has a relative molecular mass of 95 kDa and displays a faster electrophoretic mobility under non-reducing conditions. The function, cellular distribution and molecular properties of MALA-2 are indistinguishable from those of human ICAM-1.

Animals↗
PubMed1989

Cytoskeletal organization and functional changes in monocytes from patients with chronic hepatitis B: relationship with viral replication.

Monocytes play an important role in the initiation and regulation of the antiviral immune response. These cells have a dense framework of intermediate filaments composed of vimentin monomers. In 35 patients with chronic hepatitis B, 26 healthy controls, seven patients with acute liver damage and eight patients with inactive HBsAg-negative cirrhosis, we investigated the expression of vimentin filaments, C3b and IgGFc receptors, HLA-DR molecules and the phagocytic activity in monocytes purified from venous blood. In the same subjects, we also studied the display of CD2, CD3 and CD5 on lymphocytes. In patients with chronic hepatitis B manifesting viral replication (n = 21; Group 1), the expression of vimentin filaments and the other functional monocyte parameters were decreased, whereas in patients in the nonreplicative phase of the disease (n = 14; Group 2) and in control cases with various forms of acute liver damage or inactive HBsAg-negative cirrhosis, they were similar to those found in healthy subjects. In Group 1, there was also a selective defect in the display of CD3 on lymphocytes. The expression of this molecule correlated with the functional state of monocytes. In three patients with chronic hepatitis B that changed from the replicative to the nonreplicative phase of the disease, the expression of vimentin filaments in monocytes and of CD3 on lymphocytes increased to normal levels. On the other hand, the incubation of patients' monocytes with gamma-interferon corrected the diminished expression of vimentin filaments and the other decreased functional parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytoskeleton↗
PubMed1989

Suppressor T-cell activity in chronic hepatitis B-virus infection: relationship with the presence of HBV-DNA in serum.

Suppressor T-cell activity and allogeneic T-cell response to concanavalin A (ConA) were investigated in 46 patients chronically infected with hepatitis B virus (HBV). Thirty-eight patients had chronic active hepatitis, seven of whom were superinfected with Delta virus, and eight were healthy chronic HBV carriers. T-cell suppressor activity was in the normal range in healthy carriers and in patients negative for serum HBV-DNA, independent of the e antigen status. In contrast, the group of patients positive for HBV-DNA exhibited a significant reduction in suppressor activity. Longitudinal studies in patients who cleared serum HBV-DNA demonstrated that suppressor T-cell activity became normal thereafter. These results suggest a relationship between suppressor T-cell function and the stage of viral replication in individuals with chronic HBV infection.

Adult↗
PubMed1989

Systemic and regional hemodynamics in patients with liver cirrhosis and ascites with and without functional renal failure.

Systemic, femoral, and renal hemodynamics were evaluated in 7 control subjects and 20 cirrhotic patients with ascites, 14 of them without (group A) and 6 with (group B) functional renal failure. Hyperdynamic systemic circulation, increased plasma volume, and hyperreninism were present in groups A and B. These changes were more severe in group B, which showed, as compared with group A, lower total vascular resistances and mean arterial pressure together with increased cardiac index and plasma renin activity. Significant differences in regional hemodynamics were also observed between groups. In group A, femoral and renal fractions of cardiac output were respectively increased and reduced as compared with controls. By contrast, in group B, both fractions of cardiac output were reduced when compared either with controls or with group A. In the entire patient group there was a close direct correlation between femoral and renal fractions of cardiac output (r = 0.88; p less than 0.001) and both of them correlated independently with total vascular resistances (r = 0.79; p less than 0.001 in both cases). These results indicate that, in nonazotemic cirrhotics with ascites, vasodilatation in extrasplanchnic areas contributes to the genesis of the hyperdynamic circulation. The presence in group B of a reduced flow to extrasplanchnic territories, in association with an increase of the hyperdynamic circulatory status, suggests that exacerbation of splanchnic vasodilatation is involved in the development of the hepatorenal syndrome. Finally, in cirrhosis, the changes that occur in systemic hemodynamics appear to influence renal function and renal blood flow.

Aldosterone↗
PubMed1989

Phagocytic activity of polymorphonuclear leukocytes on Escherichia coli previously exposed to metronidazole.

A study was made of the action of different concentrations of metronidazole of the viability of Escherichia coli under aerobic and anaerobic conditions. The viability of E. coli was reduced by 60 to 99% after 24 hours of anaerobic incubation, according to the concentration of metronidazole tested. In addition, there were significant morphological changes in the bacteria. Exposure of antibiotic-induced filaments of E. coli LP 136 to phagocytosis caused the cfu/ml value to drop by 60% after 120 minutes. Under identical conditions, using the mutant strain E. coli RYC 819, which did not become filamented by metronidazole although it did present similar ultrastructural changes, this reduction reached 83%. These results may explain the therapeutic success of metronidazole in polymicrobial infections.

Adult↗
PubMed1989

A pilot study of thymus extract in chronic non-A, non-B hepatitis.

In previous studies it has been suggested that activation of cellular immunity may have a role in controlling the activity of chronic non-A, non-B liver disease. We conducted a pilot study of therapy with a bovine thymus extract for 6 weeks in 15 consecutive patients with chronic non-A, non-B hepatitis, most of them sporadic cases. Treatment induced immunomodulation, and in five patients a significant but transient diminution in aminotransferase levels was observed associated with increments in several parameters of cellular immunity. This suggests that a longer administration of this or other related compounds, or treatment with a more potent immunomodulating agent, might be effective in these patients.

Animals↗
PubMed1989

Opioid peptides modulate the organization of vimentin filaments, phagocytic activity, and expression of surface molecules in monocytes.

It is theorized that intermediate filaments are important in the modulation of membrane activity and cell motility; however, their functions are unknown. The assembly and organization of these filaments are under hormonal regulation. We investigated in human monocytes the in vitro effects of Met-enkephalin, Leu-enkephalin, and beta-endorphin on the expression of immunoreactive cytoskeletal vimentin filaments. We simultaneously examined their effect on the phagocytosis of Candida albicans and on the membrane display of surface molecules. The three opioid peptides markedly reduced the expression of vimentin filaments, the phagocytic activity, and the display of HLA-DR molecules at concentrations of 10(-6), 10(-8), and 10(-10) M. On the other hand, the intravenous administration of fentanyl, a synthetic opiate agonist, to patients undergoing surgery induced similar changes in monocytes. In other experiments, 10(-8) M beta-endorphin also decreased the expression of CR3 but did not influence the display of CD13, a surface protein of unknown function. Expression of vimentin filaments correlated directly with the display of HLA-DR antigens and CR3 and with the phagocytic activity. The results of this paper indicate that opiates and opioids, neuropeptides known to be released during stress, can directly depress several monocyte functions. Furthermore, from these data it may be speculated that intermediate filaments may regulate the membrane expression of some surface molecules and the phagocytic process.

Antigens, Surface↗
PubMed1989

Naloxone-reversible monocyte dysfunction in patients with chronic fatigue syndrome.

We studied monocyte function in 35 consecutive patients with chronic fatigue syndrome (CFS) and 25 healthy controls. Eighty-five per cent of the patients showed monocyte dysfunction characterized by marked reduction in the number of monocytes displaying immunoreactive cytoskeletal vimentin filaments, a low phagocytosis index, and a reduced expression of HLA-DR antigens. These values increased dramatically after incubation of the patients' monocytes with the opioid antagonist naloxone. Other immunological abnormalities also noted in the patients were low lymphocyte blastogenesis and diminished numbers of monocytes displaying receptors for Fc of IgG (FcR) and C3b (CR1). These findings suggest that an increased opioid activity acting through a classical receptor mechanism is active on monocytes from a high proportion of patients with CFS and that this represents a novel example of immunomodulation by opioid peptides in human disease. We suggest that endogenous opioids are involved in the pathogenesis of the chronic fatigue syndrome.

Adult↗
PubMed1989

[Transluminal angioplasty for aortic coarctation in newborns and infants].

It has been done transluminal angioplastic with catheter balloon in 14 patients who are under 1 year of age and who are affected by aortic coarctation. For this study, they were divided in two groups. The first one was formed by newborn children whose transcoarctation gradient was 52 mm Hg in average. The second group was integrated by 9 newborn children whose transcoarctation gradient was 59 mm Hg. After this experience was done the gradient descended to 9 and 15 mm Hg respectively. Twenty four hours later, two months later and over two more months, there were follow-up of the clinical situation, the evolution of the pulse, differential arterial pressure and the need of surgery. Of the first group only one of the patients, who is now 2 years old, is in good clinical condition; the others needed to be surgically intervened. Of the second group 4 patients, all of whom were over 3 months old at the time of the angioplastic had positive results. The rest needed surgical intervention.

Angioplasty, Balloon↗
PubMed1989

[The evaluation of the diagnostic usefulness of the clinical picture, electrocardiography and enzymes in the initial presentation of an acute myocardial infarct].

Medical data of 181 patients, affected by confirmed acute myocardial infarction, were reviewed to evaluate the initial clinical, electrographic and radiological data, and the first CPK test. Eleven patients went to the emergency department without chest pain (6.1%). The percentage of patients with oppressive chest pain was 73%, being of thoracic localization in 86.4%, 20%. Related to effort; 47.1% referred; and 92.9% of more than 30 mins. duration. 35.3% had normal blood pressure. Only 5 patients (2.8%) had normal EKG, the S-T segment elevation being the most frequent alteration (71.3%). 89.5% of patients had sinusal rhythms; 20.4% were bradycardic. 58.6% had normal levels of CPK at the first test. We concluded that EKG is the most important test in diagnosing acute myocardial infarction; it being very rarely normal. The clinical data are coadjuvant, while isolated initial CPK had not value.

Adult↗
PubMed1989

[Aortic stenosis with left ventricular systolic dysfunction: a severe disease but with good surgical prognosis].

From our series of 72 patients with severe valvular aortic stenosis, we identified 19 showing features of left ventricular systolic disfunction (ventriculographic ejection fraction less than 55% and/or fractional shortening less than 30% at M-mode echocardiography). In these patients, we found a significant inverse correlation between the fractional shortening and the systolic wall stress (r = 0.79, p less than 0.001). Clinically, 18 of the 19 patients were in NYHA class III (n = 11) or IV (n = 5), and two died before they could be operated upon. The remaining 17 had their aortic valve replaced (coronary artery bypass surgery was simultaneously performed in 2 patients). After a mean follow-up of 18 months, all patients are alive and show substantial symptomatic improvement (15 patients in class I and 2 patients in class II). Cardiothoracic index was reduced (61 +/- 5% preoperatively versus 52 +/- 5% postoperatively), and fractional shortening changed from 21 +/- 5% to 30 +/- 5%. The latter remains under normal limits in two thirds of the patients. Our results lend support to the idea that the systolic left ventricular dysfunction in aortic stenosis is due to the increased afterload, rather than to an intrinsic contractility defect. This explains the great functional improvement after the reduction of the systolic wall stress achieved by surgery.

Adult↗