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R P Laguens

Publications and source records attributed to R P Laguens.

16 recordsLinked to original sources
PubMed1979

Ultrastructural and morphometric study of the human heart muscle cell in acute coronary insufficiency.

In 13 patients with acute coronary insufficiency (intermediate syndrome, postinfarction angina, and progressive angina), samples of the ischemic area of the myocardium were studied with the electron microscope and by morphometric methods in order to describe quantitatively the mitochondrial population. Three indices were measured: the fractional volume of the mitochondrial compartment of the cytoplasm, the number of mitochondria per unit volume of heart tissue, and the average individual mitochondrial volume. As a control, the same study was performed on samples obtained from patients with chronic coronary insufficiency and mitral stenosis. In all the ischemic hearts the most conspicuous ultrastructural modification of the muscle cells consisted in an irregular distribution of the mitochondriranules. Generally, odd shaped mitochondria were found. The modifications were not diffuse, and almost normal heart muscle cells were seen alongside deeply altered ones. In addition a definite decrease in the fractional volume of the mitochondrial compartment was found, which was apparently due to a decrease in the number of mitochondria per unit volume of cytoplasm. The average individual mitochondrial volume was similar in acute coronary insufficiency and in the control cases. On the basis of this evidence it is postulated that in sublethal ischemia definite ultrastructural modifications of the heart muscle cells are associated with a decrease in the number of mitochondria per unit volume of cytoplasm.

Coronary Disease↗
PubMed1979

Presence of viral particles in the salivary gland of Calomys musculinus infected with Junin virus by a natural route.

Calomys musculinus, a wild cricetid rodent, is one of the main reservoirs of Junin virus. Six of these animals were infected by being placed in close contact with animals that had been experimentally infected with the virus. They were sacrificed at 10, 15 and 20 months after contact, and their salivary glands were studied by ultrastructural, immunohistochemical and virological methods. Two animals developed chronic viremia and low titers of complement-fixing antibodies. These animals were the only ones that had high viral titers in salivary glands and blood and viral antigen and particles in salivary glands. Although some of the other animals had viremia at the beginning of the experiment, it was absent 5 months later. Complement-fixing antibodies developed in all animals. On the basis of these findings, we assumed that the salivary gland is an important site of viral synthesis and excretion. This type of chronic infection, with persistent viremia and virus shedding, is possibly important for virus perpetuation in nature and transmission to man.

Animals↗
PubMed1979

Circulating antibodies to peripheral nerve in American trypanosomiasis (Chagas' disease).

An antibody reacting with Schwann sheaths of myelinated somatic and unmyelinated autonomic peripheral nerve was found in sixty-one out of seventy-one chronic, and nine out of ten acute, Chagas' disease sera. Indirect immunofluorescence (IFL) was carried out on rat, mouse and human somatic nerves and rat sympathetic nerves with initial serum dilutions of 1 : 10, and the staining reached a final titre of 1 : 320 in some cases. The antibodies fixed complement and were absorbed out by lyophilized epimastigotes of T. cruzi. Lipid extraction of the tissue sections enhanced the staining of myelinated nerve, whereas unfixed unmyelinated sympathetic nerve was strongly reactive. Central nervous tissue did not display any positive staining on neurons, glial cells or periaxonal sheaths. Furthermore, by using a double-labelled IFL technique, it was possible to show that a rabbit antiserum raised against guinea-pig spinal cord and the chagasic anti-nerve antibodies reacted with different structures in the rat sciatic nerve. These findings suggest that the reactive antigen(s) could be located on Schwann cells. The majority, but not all, of the chagasic individuals with anti-nerve antibodies also showed the sarcolemmal and endothelial staining (EVI) previously described in Chagas' disease. The possible recognition of Schwann cell antigens by circulating antibodies in Chagas' disease could be relevant, since an autonomic denervation has been postulated as a pathogenic mechanism of cardiomyopathy and megaviscera in this condition.

Animals↗
PubMed1978

Antigenic differences between AKR lymphoma and thymus cells leading to detection of a tumor antigen associated with immunological enhancement.

In an experimental model conditioning for enhancement, an AKR lymphoma was made to grow in BALB/c mice, permitting the simultaneous comparison of tumor-bearing (progressor) and tumor-rejecting (regressor) animals. By immunofluorescence using as target AKR lymphoma and normal thymus cells, both acetone-fixed and unfixed, it was observed that the allogeneic progressor serum contained three antibodies, two of which could be asborbed by thymocytes while the other combined selectively with the acetone-fixed lymphoma target. This tumor-specific antibody could not be detected in regressor serum which, on the other hand, could be completely absorbed by thymocytes. The identification of this acetone-resistant tumor antigen led to the preparation of aceton-treated acellular lymphoma extracts: a precipitate was obtained which upon inoculation in BALB/c mice produced an antiserum that combined selectively with lymphoma targets. In vivo experiments showed that pretreatment with this antigen led to a significant increase in allogeneic tumor incidence, 76% as compared to 37% in the controls. It is concluded that in this allogeneic model, an acetone-resistant tumor-specific antigen and the corresponding antibody are involved in tumor enhancement.

Animals↗
PubMed1977

Chagasic cardiopathy. Immunopathologic and morphologic studies in myocardial biopsies.

Immunopathologic and morphologic studies at the light and transmission electron microscope levels were carried out in myocardial biopsies of 4 chagasic individuals with circulating antibodies reacting with plasma membrane of striated muscle and endothelial cells (EVI antibody). Two cases did not present clinical evidences of heart involvement, and 2 cases showed chronic heart disease. In viv deposits of immunoglobulins were found at the plasma membrane of working myocardial cells and endothelial cells. The cytologic location of the in vivo bound gamma-globulin was coincident with the specificity of the EVI antibody. Ultrastructural studies showed intracellular alterations compatible with hypoxia of the fibers; these lesions, although they were more severe in the 2 cases with heart disease, were also present in the asymptomatic individuals. These results are congruent with a possible pathogenic effect of the EVI antibody. In 2 patients with Chagas' heart disease, foci of mononuclear infiltrates were examined by transmission electron microscopy. At that level, a close relationship between lymphoctes and muscle cells was observed, with imbrication of the plasma membranes and disappearance of the basal laminae. In the neighborhood of the lymphocytes, definite muscle cell abnormalities were found. These observations are also congruent with the recently suggested possibility that a lymphocyte-mediated immune response against heart tissue may participate in some of the pathogenetic mechanisms of chronic chagasic cardiopathy.

Adult↗
PubMed1977

Persistent glomerulonephritis following the haemolytic-uremic syndrome. Immunopathological and morphological studies.

Immunopathological and ultrastructural studies were carried out on kidney biopsies of eight children with a persistent nephropathy (PN) following the haemolytic-uremic syndrome (HUS). Significant amounts of in vivo-bound immunoglobulins and C3 were demonstrated by immunofluorescence methods in the glomeruli of all the cases, with a nodular pattern along the capillary walls. In four cases studied, C1q and C4 were also demonstrated, with an identical distribution. Transmission electron-microscope studies revealed a marked thickening of the glomerular basement membrane, and the existence of an electron-dense material with an intramembranous and subepithelial localization. With the exception of one case, serum complement studies did not present major modifications. Coagulation studies reveal that alterations observed in acute HUS were not present in the PN. Results of the present study suggest that an immune mechanism of glomerular damage operates in the pathogenesis of the PN observed after HUS, leading to a normocomplementemic, chronic glomerulonephritis. Although a hypothetical antigen (or perhaps several antigens) remains to be demonstrated, immunofluorescence and electron-microscope studies suggest the deposition of immune complexes in the renal lesions.

Autoantibodies↗
PubMed1976

Effect of chagasic sera on the rat isolated atrial preparation: immunological, morphological and function aspects.

An antibody reacting with the plasma membrane of working myocardial cells, skeletal muscle fibres, and endothelial cells (EVI antibody) has been described in the sera of patients with Chagas' disease. In the present study of rat isolated atrial preparations beating in ddifferent media, direct immunofluorescence and ultrastructural immunohistochemical procedures indicate that the antibody can interact with the living tissue, becoming fixed to the plasma membranes. Transmission electronmicroscopy studies also showed the presence of sarcolemmal alterations. These observations suggest a possible pathogenic effect of the EVI antibody. The presence of EVI-positive sera in the beating medium leads to a significant increase in the frequency of contractions; no significant effects of EVI-positive sera in contractile force were seen. The increase in frequency could be prevented by previous treatment with a b-adrenergic blocking agent (MJ-1999), but not by an x-blocker (phentolamine) or by an anti-histamine compound (cyproheptadine). The changes described were observed only in those atrial preparations which were beating in media containing EVI-positive sera. In those atria beating in control media (KR,KR plus normal human serum, KR plus EVI-negative chagasic serum), neither immunological nor morphological or functional changes wersence of EVI-positive chagasic serum diminished atrial stimulation after added norepinephrine. These results suggest the possibility that the EVI antibody may act as a b-adrenergic agonist at the cell plasma membrane level. Such an effect might account for some of the clinical features of chronic Chagas' heart disease.

Animals↗
PubMed1975

Ultrastructural and immunohistochemical studies in five cases of Argentine hemorrhagic fever.

Ultrastructural and immunohistochemical studies on tissues from five patients with Argentine hemorrhagic fever revealed previously undetected lesions caused by the viral infection. Two types of particle were seen in the cells of all organs examined. The particles had some characteristics similar to those described for arenaviruses. However, the virus-like particles were intracellular, had a single membrane, and apparently originated by a process of budding into the endoplasmic reticulum cisternae. Intranuclear bodies and three types of cytopolasmic change were observed in conjunction with the virus-like particles; Antigenic determinants of Junin virus were demonstrated in cells of all organs examined. Immunohistochemical experiments also indicated alterations in the cellular mechanisms of protein synthesis. Until now the pathogenesis of human diseases produced by arenaviruses has not been established. The results of this study suggest that in Argentine hemorrhagic fever the virus is responsible for a direct pathogenic action.

Adult↗
PubMed1975

Immunopathologic and morphologic studies of skeletal muscle in Chagas' disease.

Skeletal muscle biopsies from 21 individuals infected with Trypanosoma cruzi were studied my means of immunofluorescence, ultrastructural immunochemical, light and electron microscopic, and histochemical procedures. In 12 cases, definite morphologic alterations were found. These alterations were coincident with the presence of circulating antibodies against the plasma membrane of striated muscle fibers and endothelial cells (EVI antibodies). In almost all cases the lesions also presented autologous immunoglobulins bound to the plasma membrane of muscle fibers and endothelial cells. Interstitial inflammatory exudate was not observed in the diseased muscle. On the basis of these observations, it is suggested that the EVI antibody is related to some of the pathogenetic mechanism of skeletal muscle damage in Chagas' disease.

Adenosine Triphosphatases↗
PubMed1975

Immunological studies in Rockland mice infected with T. cruzi. Development of antinuclear antibodies.

The existence of antinuclear antibodies (ANA) and their relationship with anti-Trypanosoma cruzi specific agglutinins was studied in Rockland mice inoculated with 10(5), 10(4) or 10(3) epimastigotes and 2 X 10(5) trypomastigotes of T. cruzi. ANA and anti-T. cruzi agglutinins were detected at the same time in groups of mice receiving 10(5) culture forms, while in those groups of mice receiving 10(4) parasites agglutinins were established earlier than ANA which were present only at low titres. Positive serology and ANA were also detected in mice infected with trypomastigotes. Neither specific agglutinins nor ANA were found in groups of mice receiving 10(3) parasites probably because the number of parasites inoculated was too low to infect them. ANA were not found in not infected mice. ANA induced in mice by T. cruzi infection seem to be related to the amount of parasites inoculated and thus with the degree of the subsequent infection. Immunopathologic studies carried out in mice infected with trypomastigotes showed the presence of nodular deposits of gamma globulin in the kidneys, suggesting the possibility of an immune complex disease : the light and electron microscopic studies of the kidneys showed in the glomeruli an increase of the mesangium, hypercellularity and thickened basement membranes.

Animals↗