PubMed Health⌕ Search

Biomedical subjects

L M Scavini

Publications and source records attributed to L M Scavini.

At least 19 recordsLinked to original sources
PubMed1990

Evaluation of the high density lipoprotein cholesterol protective effect against atherogenesis in rabbits fed cholesterol supplemented diets.

Plasma high density lipoprotein cholesterol (HDL-C) was evaluated in 15 rabbits fed cholesterol supplemented diets to assess its protective effect on the atherogenic process. From a baseline level of 29 +/- 11 mg/dl (mean +/- SD) the maximum attained for HDL-C was twofold in only three rabbits, whereas total cholesterol (TC) increased 20 fold. Plasma TC/HDL-C ratio rose 80 fold from the baseline (2.4 +/- 0.9) and it was the best parameter that correlated with aortic cholesterol accumulation and pathological scores. Aortic TC content increased 10 fold and free cholesterol/cholesterol esters ratio decreased 20 fold. Pathological studies showed that aortic lesion scores rose from 0 to 4. It can be concluded that the high correlations obtained when TC/HDL-C ratio was plotted against both aortic cholesterol deposition and lesion scores, support the theory of the reverse cholesterol transport and the effectiveness of this index to predict the degree of the atherogenic process. On the other hand, the poor response of HDL-C in this model encourages future research using drugs to increase this parameter in order to normalize TC/HDL-C ratio and avoid lesions.

Animals↗
PubMedDate not supplied

Bat feces as an indoor allergen.

We have demonstrated in an animal model (specific IgG) as well as in atopic patients suffering from rhinitis/asthma (specific IgE) that bat feces have antigenic properties. A single peak with high glycoprotein content was obtained by chromatography, while SDS-PAGE revealed several proteins between 29 and 116 kDa which showed immune serum blotting at 43.6 and 66 kDa. Positive specific skin tests with bat feces and IgE-RAST anti-bat feces were detected in atopic patients living in tall buildings and old houses in Buenos Aires. As bat feces did not cross-react with bat epithelium, studies evaluating rat serum and epithelium and pigeon feces in order to analyze the role of bat serum proteins, such as IgA, are encouraged.

Adult↗
PubMedDate not supplied

Immunological changes during cockroach immunotherapy.

Data obtained in a 3-year survey of specific immunotherapy (SIT) with a Periplaneta americana antigen (Pa-1) are presented. Parameters such as serum IgE-paperadioimmunosorbent test, specific IgE and IgG, interleukin (IL)-2, IL-4 and IL-4R levels were recorded before and after SIT. While serum IgE levels and IgE-RAST-anti-Pa-1 did not change throughout SIT (p = not significant), IgG-RAST-anti-Pa-1 showed a marked increase from the first year (p < 0.002 to p < 0.001). Only after 3 years of SIT did the serum levels of IL-2, IL-4 and IL-4R show lower values than before this period (p = 0.05, p = 0.05, p = 0.01, respectively). The comparative statistical analysis of the cytokine data between the nonatopic subjects and the atopic treated patients revealed no significant differences (p = 0.02). The symptomatic scores showed significant results at the third year of SIT in sneezing attacks, nose blowing and nasal obstruction (p = 0.001, p < 0.001, p = 0.001, respectively).

Adolescent↗
PubMedDate not supplied

IgE antibodies against Neisseria flavescens.

Bacterial allergy is still a matter of controversy. We sustain that this name should be employed only in the presence of a specific IgE against antigens from bacteria. In 100 atopic patients and 100 healthy controls with Neisseria flavescens in their pharyngeal exudates, we performed type I immediate skin tests with Neisseria flavescens and IgE-RAST throughout 1 year. Positive wheal and flare reactions were elicited in 8 of 100 atopic patients as well as in 3 of 100 nonatopic subjects. IgE-RAST/anti-Neisseria flavescens was found in 6 of the former group and in 1 of the latter. Neither late-phase nor Arthus-like reactions were recorded. Neisseria flavescens is a non-pathogenic commensal of the oropharynx with scarce antigenic properties and seems not to play an important role in these conditions (rhinitis/asthma). Bacterial immunotherapy should be considered only in the presence of specific IgE antibodies with careful selection of the bacteria or their antigens.

Adult↗
PubMedDate not supplied

Immunochemical properties of the antigens of Triatoma infestans.

Taxonomically related to the cockroach Periplaneta americana (Pa), Triatoma infestans (Ti) is an insect that parasitizes two-thirds of Argentina and acts as a vector for American trypanosomiasis. The glycoproteins obtained by a Sephadex G-150 column fractionation from the whole-body extract prepared with the chitinous structures revealed antigenicity in rabbits, which developed specific IgG after 8 weeks of immunization, as detected by several serological techniques. Atopic patients living in the northern provinces of Argentina--Santiago del Estero and Chaco (endemic area for Ti)--with rhinitis/asthma showed immediate positive skin tests to Ti and its fractions, as well as an IgE-RAST-anti-Ti in 30-36% of them. Healthy nonatopic adults of the same area and other atopics and nonatopics from Buenos Aires (non-endemic area) were selected as controls and showed negative type I skin tests, as well as specific RAST. The existence of common epitopes between Ti and Pa was confirmed by absorption techniques, RAST inhibition, IEF and STIF-RAST. These findings have clinical and epidemiological connotations.

Adult↗
PubMedDate not supplied

Antigenicity of Penicillium notatum in animals and in atopic patients.

A mycelial and metabolic extract of Penicillium notatum (PN) was passed through Sephadex G-50 and DEAE-cellulose columns in order to separate soluble fractions that revealed a complex composition. Their proteins and hexoses were recorded with a LKB Uvicord spectrophotometer and quantified by the Lowry and the indol techniques. On the other hand an animal model was developed in rabbits and an IgG precipitin and hemagglutinating antibodies were obtained. The PN extract as well as those fractions with the higher protein content appeared positive when they were checked against the antiserum by means of Ouchterlony, Boyden and immunoelectrophoresis. The molecular weight of PN was established in 52,000 daltons approximately in comparison with well known marker proteins. Adult human beings suffering perennial rhinitis and bronchial asthma showed positive type I skin tests with PN and its most conspicuous fractions (glycoproteins). A RAST-IgE-anti-PN was prepared following Ceska's procedure and challenged against all human sera. Only 40% of the patients revealed a positive RAST IgE-anti-PN which correlated significatively with the protein fractions (35%) and with the skin tests (43% and 39%, respectively). These results reinforced the idea that PN is a potent antigenic mold both in animals and in humans in whom we detected an IgE specific antibody presumably related to their atopic clinical condition.

Adolescent↗
PubMedDate not supplied

Induction of anti-orange antibodies in rabbits.

The capacity of certain foods to cause allergic reactions is well known. The four types of mechanisms that Gell and Coombs described in 1968, are involved in these reactions, although the reaginic antibodies retain the paramount attention of the immunologists. The physiochemical composition of the allergen molecule is the goal of investigators with the purpose to clarify the intrinsic kinetics of antibody synthesis. This paper contributes to the conflicting data about orange allergens especially those obtained from Citrus Aurantium Sinensis and Citrus Silension (CAS and CS, respectively). Glycoproteins were separated by gel filtration through a Sephadex G-50 column. A definite protein peak was obtained meanwhile several hexoses appeared throughout the fractionation procedure. These molecules have adequate physiochemical properties that make them able to trigger the immunological response (molecular weight, definite chemical composition and glycoprotein content). Although CAS and CS have a similar chemical composition a slight inverse proportion of proteins and hexoses was demonstrated between the two classes. Molecular weights were different for CAS (51.500) and for CS (37.000) in comparison with well established protein makers. Ouchterlony revealed two precipitin lines in the CAS-anti-CAS system but none in the CS-anti-CS one. The Boyden technique showed a titre of 1/256 in the first case and only of 1/64 in the second of specific anti-orange antibodies. All the eluted fractions gave negative results although they were concentrated ten times by pre-evaporation. This animal model reinforced the statement that after a long and continuous exposure to orange antigens it was possible to develop specific antibodies. It is assumed that this phenomenon happens in atopic children with it's diagnostic and therapeutic importance.

Allergens↗
PubMedDate not supplied

Immunochemical properties of the antigens involved in the pigeon breeder's disease.

The pigeon breeder's disease is a form of extrinsic allergic alveolitis caused by the exposure to pigeon droppings. Chemical analysis of this antigen was carried out employing column fractionation techniques. Sephadex G-50 and DEAE cellulose were performed and several proteins and hexoses peaks were recorded. Molecular weights were determined by comparison with standardized marker proteins passed through a drop counting fraction collector. The whole extract revealed a molecular weight of 100 Kd while fraction 1 showed 66 Kd and fraction 2 only 30 Kd. A guinea pig experimental model was developed with the whole extract injected by the intradermal route, administered by an intragastric catheter or aerosolized in a glass chamber. Histopathological studies were carried out with the lungs, kidneys, liver and spleen obtained by the necropsy of the animals. The lungs and the kidneys showed the paramount changes in their structures with lymphomononuclear infiltrates and an Arthus-like phenomenon surrounding the vessels. Immunological techniques were applied to the sera and the lymphocytes obtained from the animals. Precipitin and hemagglutinating IgG antibodies were detected against the whole extract and the fractions obtained by column fractionation. Sensitized lymphocytes were also detected. This experimental model represents a guide in the approach to the human allergic alveolitis whose immunological findings will be presented in a forth-coming report.

Alveolitis, Extrinsic Allergic↗
PubMedDate not supplied

Immunological findings in human beings with autoimmune uveitis.

Thirty-four adult patients suffering from uveitis of unknown origin were submitted to an immunological protocol where specific and non-specific parameters were checked. Serum IgA, IgG and IgM appeared within normal values meanwhile IgE-PRIST was undoubtedly increased in 27 out of 34 patients. The presence of autoantibodies such as antimitochondrial and antismooth muscle were detected in a few patients with Harada's syndrome; high serum levels of immune complexes were also detected in this little group of patients with posterior uveitis. Serum complement fractions showed no significant changes. Antirretinal IgG antibodies were present in almost 40% of the patients especially in those who also have autoantibodies and immunocomplexes. The histoimmunofluorescent technique revealed positive images at the retinal membrane agreeing with the histopathological lesions obtained in the experimental model. The positive cross reactivity between bovine tissue sections and the sera from patients with uveitis reinforced the idea of the presence of common epitopes in the S-antigen of both origins. LT-CD4 and LT-CD8 serum lymphocytes showed contradictory results though both subpopulations appeared diminished. The ratio between them kept within the normal range or slightly increased (2.3-2.8). Sensitized lymphocytes to the S-antigen were detected by the MIF technique in one-third of the patients. The presence of IgG antiretinal antibodies led us to speculate about the possibility that an ADCC mechanism could also participate in the etiopathogenesis of the autoimmune uveitis. On the other hand the presence of a specific antiretinal IgE antibody must play a paramount role in increasing the vascular permeability and thus enhancing the humoral and cellular events in the inflammatory focus.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Immunochemical properties of the antigens of Blattaria sudamericana.

An extract of the cockroach Blattaria sudamericana (BS), a very common insect in Argentina, was passed through Sephadex G-200 and DEAE cellulose ion exchange columns. This method yielded 2 proteins and 6 hexoses whose quantities were determined by absorbance in a LKB Uvicord spectrophotometer at 280 nm and 470 nm respectively. Protein contents were also recorded by the Lowry method and the micro-Kjehldal technique. Adult albino rabbits were immunized with a mixture of BS and complete Freund's adjuvant over a period of thirteen weeks. The antisera obtained were studied by the Ouchterlony method, the immunoelectrophoresis and the passive hemagglutination technique against BS and the eluated fractions with the highest protein content. Molecular weights were studied with the usual marker proteins subjected to gel filtration by a Sephadex G-200 column. Each protein concentration was 13.5 mg/ml in a volume of 1.5 ml meanwhile BS was 42 mg/ml. This antigen showed a molecular weight of 180,000 daltons. Fifty untreated atopic patients of both sexes with ages between 19 and 74 years suffering perennial rhinitis and bronchial asthma were chosen according to the American Thoracic Society criteria. Their IgE levels ranged between 110 and 3000 KU/L with an average of 620 KU/L. IgE anti-BS-RAST showed positive results in half of the patients while type I positive skin tests with BS 1:100 appeared in 62% of the atopic group.

Adult↗
PubMedDate not supplied

[Autoimmune uveitis. I. Immunochemical properties of the soluble fractions of bovine retina].

Adult albino rabbits were immunized with bovine retina and complete Freund's adjuvant by the intradermal route. Blood was obtained by complete bleeding of the rabbits and stored at -20 degrees C. Their eyes were enucleated and submitted to histopathological techniques. Humoral antiretinal antibodies were detected by Ouchterlony, immunoelectrophoresis and crossed-immunoelectrophoresis, yielding precipitins presumably of the IgG type. Sensitized lymphocytes were also detected by their incubation with the retinal extract and the soluble fractions belonging to the peaks no 1 and no 2 ("S antigen") in the MIF and TTL techniques. The whole extract was passed through a Sephadex G 100 and DEAE cellulose columns and several soluble fractions were obtained. Two major protein peaks were detected (no 1 and no 2) that were subdivided into five other protein peaks (1A, 1B, 2A, 2B and 2C). Sugars were not present and molecular weights were 50,000 daltons for peak no 2 and higher than 66.000 for peak no 1. The whole protein content of the extract and of the different soluble fractions were established by the Lowry method. Histopathological studies revealed extensive lesions of the uveal tract consisting of a cellular infiltrate rich in lymphocytes and monocytes. Increased vascularization of retina was also appreciated. This experimental model represents a guide in the approach to the human uveitis of unknown origin whose immunological findings will be presented in a forthcoming issue.

Animals↗
PubMedDate not supplied

Isolation and characterization of soluble fractions of Dermatophagoides farinae.

Dermatophagoides farinae extract was filtered through Sephadex G-50 and DEAE-cellulose columns to study its chemical composition. Fractionation on Sephadex G-50 resulted in one definite peak of protein and in three sugar peaks. Fractionation of the protein peak on DEAE-cellulose produced four more protein peaks and another five sugar peaks. Twenty-one untreated allergic patients suffering from perennial rhinitis and bronchial asthma with clinical sensitivity to house dust were subjected to skin tests with house dust 1:100, dermatophagoides farinae 1:100 and also its thirteen eluted fractions 1:100. Positive results were recorded with house-dust, mite and six or perhaps seven fractions consisting of three or four proteins and three sugars. Immunization in rabbits with mite extract revealed only one slight precipitin band by the Ouchterlony technique and a 1:20 titer of hemagglutinating antibodies. The antigen or antigens of mite extract seemed to be producers of type I reactions rather than circulating antibodies of the IgG class. This represented a point of controversy for the therapeutic application of Dermatophagoides farinae in human desensitization.

Allergens↗
PubMedDate not supplied

[Immunochemical properties of secretory IgA of human colostrum].

Immunochemical properties of secretory IgA obtained from the colostrum of healthy post-partum women are discussed. Lipids were completely eliminated by centrifugation and the supernatant was adjusted at pH 8.0 with NaOH and dialysed against a PBS buffer. Fractionation through a Sephadex G-200 column was fractionated again through a DEAE-cellulose column which eluted only pure IgA. Aliquots of 3 ml each were checked for protein content in an Uvicord spectrophotometer at 254 millimicron. Three fractions were obtained from the Sephadex column, the first involving tubes 50 to 90 contained IgA and IgM, the second from tubes 91 to 120 contained IgG and the third from tubes 130 to 150 contained alfa-lactalbumin and lactotransferrin. Passage of fraction I through a DEAE-cellulose column led to the collection of pure IgA in tubes 45 to 80 with the highest content in tube 53 which was employed in the immunization of rabbits. Ouchterlony immunodiffusion and immunoelectrophoresis were employed to check the reactivity among whole colostrum as well as Sephadex and DEAE-cellulose fractions against an anti-IgA, anti-IgM, anti-IgG, anti-immunoglobulins and anti-whole human sera. Several precipitin bands revealed that human colostrum contained IgA, IgG, and IgM. Pure secretory IgA was used to immunize adult rabbits with complete and incomplete Freund's adjuvant for a period of two months. A rabbit anti-IgA serum was then obtained and after being purified by saline precipitation and dialysis and passed through a DEAE-cellulose column, was labeled with I-131 reaching a specific activity of 20 microCi/mg. This antiserum was used against human colostrum, normal serum and saliva, and serum and urine from a patient with an IgA myeloma confirmed by means of precipitin methods and autoradiographies. Chemical purity of the secretory IgA was confirmed by analytic ultracentrifugation obtaining a sedimentation value of S 20: 10.5. In all cases a single precipitin band was obtained in spite of the low concentration of the antigens; the isotopic labelling did not alter the specificity and the sensitivity of the antiserum and its usefulness was well established. The biological properties of secretory IgA are described and its importance in local immunity is emphasized.

Antibodies, Anti-Idiotypic↗
PubMedDate not supplied

IgE antibodies against snake venoms.

A similar event was detected in the clinical records of a small group of atopic patients living in the northern provinces of Argentina, i.e., they were bitten by a snake of the Bothrops species (or yarará) during their rural activities (woodcutters, cattle-drivers and farmers). Those who were bitten twice suffered an acute episode of hives and angioedema within 15 minutes after the snake bite. The presence of specific antibodies against Bothrops alternata (Ba) extract was detected by means of RAST for IgE and Ouchterlony and Boyden for IgG. The Ouchterlony also demonstrated crossreactivity among the venoms of the Bothrops species and the positivity of the six fractions obtained by DEAE-cellulose column fractionation against the horse anti-Ba serum. The Ba antigen induced a definite inhibition of the RAST. We presume that hives and angioedema in atopic patients immediately after a second snake bite could be attributed to the presence of a specific IgE antibody against the venom, and must not be misinterpreted with the toxic effects that appear later.

Adult↗