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Biomedical subjects

M Marcantoni

Publications and source records attributed to M Marcantoni.

13 recordsLinked to original sources
PubMed1989

Changes in the shape and optical properties of the chicken lens after vitreous and scleral removal.

Ocular dimensions and lens refractive properties were studied in enucleated eyes from 5-day old chicken (Gallus domesticus). Measurements were made in frozen hemisections and in fresh eyes sectioned through a para-equatorial plane. In these specimens, lens properties were examined after systematical removal of the vitreal mass. This procedure caused significant changes in lens diameter and refractive properties. Our data indicate that avian lens shape could be controlled by vitreal pressure and/or scleral support.

Accommodation, Ocular↗
PubMed1985

[Immunologic identification of Streptococcus mutans using microimmunodiffusion and counterimmunoelectrophoresis technics].

The St. mutans strains studied were: HS6 "a"; BHT "b"; IB "c"; B13 "d"; LM7 "e"; OMZ175 "f"; OMZ65 "g"; SL1 "SL"; 6715 "d/g". Immune sera and antigen preparation as well as antigen-antibody reactions were performed using the above-mentioned strains. The immune sera were obtained following Knox technique, including formolated immunogen with and without adjuvant. Linzer method was followed for rabbit immunization. The antigen extract were prepared according to Rantz and Randall method. The antigen-antibody reaction were carried out by microimmunodiffusion (MID) Ouchterlony technique and by counterimmunoelectrophoresis (CIE) according to De Torres method. A good correlation was found in the antigen-antibody reactions for the serotypes studied. MID and CIE revealed some cross-reactions, as already described by many investigators. The results obtained are compatible with St. mutans antigenic instability. The eight serotypes from St. mutans could possibly be reduced to four related groups: Group 1: serotypes "a-d-g-SL"; Group 2: serotype "e-f"; Group 3: serotype "c" (uncertain position: it can be related with group 1 or 2); Group 4: serotype "b". CIE is a convenient technique to be incorporated for immunological determination.

Antibodies, Bacterial↗
PubMed1983

The structural basis of ocular accommodation in the chick.

The structures involved in ocular accommodation were studied with scanning electron microscopy in 5-day old chicken. Particular attention was paid to the ciliary muscle that was found to be subdivided into an anterior and a posterior portion. Since the anterior portion inserted on the wall of canal of Schlemm, we postulate that it could somehow control the flow of aqueous humour. According to its insertions, the posterior muscle could stretch the choroid coat. Thus, changes in the refractive power of the eye would be brought about by an indirect mechanism.

Accommodation, Ocular↗
PubMedDate not supplied

[Difference between dental plaque formation by Lactobacillus Sp. and Strep. mutans].

Human teeth were suspended in a basal medium with sucrose 10%; they were incudated for formation of dental plaques "in vitro". The microorganisms used were: Strep. mutans, Lactobacillus salivarius var. salivarius and a mixture of them. The following aspects were stablishad by scanning electron microscopy: 1) The teeth inoculated with Strep. mutans had coccoid forms, lying on an organic film with spheric spaces in some sectors, and irreguar forms in others (Fig. 1). 2) The teeth inoculated with Lactobacillus salivarius had rod forms attached to the adamantine surface (Fig. 2, 3). 3) Teeth incubated with the mixutre had rod forms over a granular film (Fig. 4). 4) The control teath did not have plaque (Fig. 5). This experience shows that the extracellular polisacharide, reticulated or granular (mutano) appeared only in teeth incubated with Strep. mutans alone (Fig. 1) or mixed with Lactobacillus (Fig. 4). On the other hand Lactobacillus appeared attached on the enamel surfaces, perhaps due to cohesive adhesive forces (Fig. 2). Two different interpretation or the formation of dental plaques that take place on the enamel free surfaces of teeth are presented.

Culture Media↗
PubMedDate not supplied

[Clinical and microbiological study of adult periodontal disease].

The aim of this study was to carry out a microbiological evaluation of sites with and without clinical evidence of moderate and severe periodontitis and their correlation with clinical parameters. A total of 52 disease sites and 10 healthy sites were selected according to clinical criteria. The following clinical indexes were measured for all the sites: plaque index, gingival index, blood on probing, depth on probing and insertion level. Samples of subgingival plaque were collected for culture and for differential counts of microbial morphotypes. In disease sites the most frequently isolated were: Prevotella intermedia/nigrescens (65%), Porphyromonas gingivalis (23%), Actinobacillus actinomycetemcomitans (23%), Fusobacterium nucleatum (10%) and Peptostreptococcus sp. (31%). The aerobic gram-positive microflora was predominant in healthy sites. Significant differences were observed in microbial morphotypes between healthy and disease sites: cocci 18.71% and 78.90%, motile rods 46.12% and 16.70%, total spirochetes 26.48% and 2.80%, respectively. The presence of motile rods, spirochetes and P. intermedia/nigrescens were the parameters with most sensitivity to suspect periodontal disease. There were significant differences in the subgingival microflora between healthy and disease sites in patients with moderate and severe periodontitis.

Actinobacillus Infections↗
PubMedDate not supplied

Effect of self-brushing with acidulated phosphate fluoride (pH 5.6) on dental caries in children.

The aim of this work was to study the effect of a preventive program on the dental plaque and on the caries incidence in school children. The program comprised weekly supervised self brushing with acidulated phosphate fluoride (APF) gel (pH 5.6; concentration: 4520 ppm of ion F-). The program involved 240 children of 1st., 3rd and 5th grade of a primary school in the City of Buenos Aires (Argentina). The population was divided in 2 groups: A (experimental) and B (control). Ninety children from both groups (45 experimental and 45 control) were submitted to baseline clinical examination (DMFT and plaque index) and microbiological analysis (total streptococci, St mutans and St. mutans and St. mutans percentage). Group A was then submitted to a preventive program which included self brushing with APF gel (4520 ppm of ion F-). The 90-children sample was monitored after 1 and 2 years of program. Results were statistically processed and they revealed the following: a--DMFT was significantly greater in the control group than in the experimental group after 1 and 2 years of program; b--an 81.43% reduction in caries increment rate at the end of the 2-years program in the experimental group as compared to the control group; c--a rise in the number of colonies of total streptococci and of St. Mutans; d--a reduction in the % of St. mutans in the total streptococci flora in the plaque of children in the experimental group; e--the presence of St. mutans colonies featuring a rough surface; f--the effectiveness of the program in the modifying the profile of the diagnosed dental pathology.

Acidulated Phosphate Fluoride↗