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Biomedical subjects

S Petti

Publications and source records attributed to S Petti.

At least 37 records · Page 2Linked to original sources
PubMed1994

[A comparison between 2 different methods for calculating the percentage of anaerobic microorganisms in the subgingival microbial flora].

The percentage of anaerobic micro-organisms in the subgingival microflora represents a simple microbiological index which not only refers to the state but also the risks of periodontal health. The present study aimed to compare two different methods of calculating this index. The study was performed in 45 subjects with moderate gingivitis provoked by the previous application of dental fixtures anchored to both arches. A sample of subgingival microflora was collected from each patient at the level of the vestibular gingival sulcus of the first upper right molar. This was then vortexed, diluted and inoculated in three series of plates. It was chosen to use Walker's culture medium. The total bacterial count was evaluated by incubating the first series of plates in anaerobiosis; the anaerobic bacterial was calculated by subtracting from the total the of facultative aerobic-anaerobic micro-organisms, which in turn was obtained using two methods: the first (method AE) consisted of incubating another series of plates in aerobiosis; the second (method M) involved incubating the last series of plates in anaerobiosis, and adding metronidazole to the culture medium in a solution of 2.5 mg/l. The plates were then kept at 37 degrees C for seven days. The mean percentage of anaerobic microorganisms, given by the percentage ratio between anaerobic and total, relating to the 45 cases studied, was as follows: using method AE: 57.8 +/- 26.3%, and using method M: 40.2 +/- 27.2%. Both figures come close to that proposed and calculated using a much more sophisticated method by Slots, namely 41.5 +/- 19.2% in the event of gingivitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

[3 different methods for evaluating Streptococcus mutans in the saliva].

Three different methods for detection and count of Streptococcus mutans in saliva have been compared with a microbiological method in order to estimate their efficacy and practicality. The study has been carried out on fifty children of six-eleven years old. The first method (stamp method) derives from that of Kohler and Bratthall, improved on the sampling, without saliva stimulation and, hence, more rapid. Furthermore, using a tongue depressor with a shovel-like extremity, we can either restrict the area where the grown colonies must be counted, avoiding any mistake, and stamp the spatula in the centre of the plate, not in the border, as the original method described, pressing it with the same force in every part, so that almost all the saliva collected can be plated on the Streptococcus mutans selective medium. As stated by this method, a tongue depressor is pressed first on the subject's tongue, then on a plate containing the medium. After incubation, the Streptococcus mutans colonies are counted on the plate's area limited by the stamp of the extremity of the spatula. According to Emilson we can also discriminate Streptococcus mutans and Streptococcus sobrinus colonies. The second method is a "strip mutans test" (Dentocult): saliva is stimulated making the subject chew a piece of paraffin and then it is collected passing a plastic spatula for ten times on the child's tongue. The spatula is introduced into a tube containing a liquid medium selective for Streptococcus mutans and then incubated.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteriological Techniques↗
PubMed1992

[The clinical and microbiological evaluation of the efficacy of oral irrigation on the periodontal tissues of patients wearing fixed orthodontic appliances].

The aim of the present study has been the evaluation of the effectiveness of oral irrigation with or without toothbrushing and dental flossing, in individuals treated with fixed orthodontic appliances, on controlling the development of dental plaque and, hence, of gingivitis. Eight individuals with a good general and oral status have been chosen. Before the experimental period, they received instructions about oral hygiene with toothbrushing and dental flossing and then they have been monitored to verify they were doing well. At the time T0, the upper tooth have been banded, three Periodontal Indexes (Plaque Index according to Silness and Loe, Modified Gingival Index according to Lobene and Gingival Bleeding Index according to Ainamo and Bay) registered and subgingival plaque samples from the premolars' gingival sulcus collected in order to point out the total anaerobes bacterial counts, the rates of motile bacteria, spirochetes, Gram positive and Gram negative cocci and bacteria, by means of optical and dark field microscopy and of cultural methods. For their oral hygiene, the patients had to use, in the right side toothbrush and dental floss (Control 1), in the left side the oral irrigator alone (Test 1). One month later (time T1), the lower teeth have been banded, too. In the right side the patients had to use toothbrush and dental floss (Control 2), while in the left one they used the same devices as Control 2 plus the oral irrigator (Test 2). At the time T1 Periodontal Indexes and Microbiological analyses have been extended to all the four quadrants.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Granulocyte-macrophage colony-stimulating factor reactivates fetal hemoglobin synthesis in erythroblast clones from normal adults.

Reactivation of fetal hemoglobin (HbF, alpha 2 gamma 2) synthesis was previously reported in normal human adult erythroblast colonies ("bursts") generated by erythroid progenitors (BFU-E) in fetal calf serum-supplemented (FCS+) semisolid cultures stimulated with erythropoietin (Ep). Our studies focused on the reactivation of HbF synthesis in normal adult erythroid bursts generated by peripheral blood mononuclear cells (PBMCs) seeded in FCS+ methylcellulose culture. Reactivation is almost totally suppressed when (a) PBMCs are grown in optimized FCS- culture, or (b) PBMCs are first stringently depleted of monocytes and then plated in FCS+ medium (ie, BFU-E growth in FCS+ Mo- culture). In both experimental conditions, the proliferation of lymphocytes and macrophages interspersed among colonies is drastically reduced, and the cloning efficiency of granulocyte-macrophage (GM) progenitors is sharply diminished. In either case, addition of biosynthetic GM colony-stimulating factor (GM-CSF) induces a dose-related increase of HbF synthesis up to the level in FCS+ culture, with even more elevated values on delayed addition of Ep. A dose-related increase was also observed in erythroblast clones generated by highly purified BFU-E. These results suggest that reactivation of HbF synthesis in normal adults is at least in part mediated by GM-CSF. Furthermore, they imply intriguing hypotheses on the mechanism(s) of perinatal Hb switching. Finally, they raise the possibility of reactivation of HbF synthesis in beta-thalassemia and sickle cell anemia by GM-CSF therapy.

Biological Factors↗
PubMed1989

Erythropoietin alone induces erythroid burst formation by human embryonic but not adult BFU-E in unicellular serum-free culture.

Erythroid progenitors (BFU-E) from adult human peripheral blood generate erythroid bursts in semisolid culture supplemented with at least two growth factors, ie, erythropoietin (Ep) and interleukin-3 (IL-3) or granulocyte-macrophage colony-stimulating factor (GM-CSF). We have analyzed the hematopoietin(s) requirement of human embryonic BFU-E, as compared to that of adult peripheral blood progenitors: This was basically evaluated in fetal calf serum-free (FCS-) methylcellulose culture of partially or highly purified progenitors treated with human recombinant hemopoietins. At a low seeding concentration (2 x 10(3) cells/dish) purified embryonic BFU-E generated erythroid bursts when treated only with Ep: Further addition of IL-3 or GM-CSF had no effect on BFU-E cloning efficiency, although the size of bursts was increased in a dose-dependent manner, particularly with IL-3. At a similar seeding concentration (ie, 10(3) cells/dish), purified adult BFU-E efficiently generated erythroid bursts in the presence of Ep and GM-CSF or IL-3, while only few small erythroid colonies were observed in the presence of Ep alone. In a final series of experiments, unicellular FCS-cultures of purified embryonic BFU-E gave rise to erythroid bursts in the presence of Ep alone. Furthermore, the cloning efficiency induced by Ep was unmodified by further addition of GM-CSF or IL-3. Unicellular FCS- cultures of highly purified adult peripheral blood progenitors generated no erythroid bursts in the presence of Ep alone. The addition of GM-CSF or IL-3 was required to generate BFU-E colonies. These studies indicate that in human embryonic life, BFU-E require only Ep for efficient erythroid burst formation, while IL-3 and GM-CSF essentially enhance the proliferation of early erythropoietic precursors.

Cells, Cultured↗
PubMed1986

Human embryonic hemopoiesis. Kinetics of progenitors and precursors underlying the yolk sac----liver transition.

Human embryonic development involves transition from yolk sac (YS) to liver (L) hemopoiesis. We report the identification of pluripotent, erythroid, and granulo-macrophage progenitors in YS, L, and blood from human embryos. Furthermore, comprehensive studies are presented on the number of hemopoietic progenitors and precursors, as well as of other cell types, in YS, L, and blood at precisely sequential stages in embryos and early fetuses (i.e., at 4.5-8 wk and 9-10 wk postconception, respectively). Our results provide circumstantial support to a monoclonal hypothesis for human embryonic hemopoiesis, based on migration of stem and early progenitor cells from a generation site (YS) to a colonization site (L) via circulating blood. The YS----L transition is associated with development of the differentiation program in proliferating stem cells: their erythroid progeny shows, therefore, parallel switches of multiple parameters, e.g., morphology (megaloblasts----macrocytes) and globin expression (zeta----alpha, epsilon----gamma).

Colony-Forming Units Assay↗
PubMed1984

Hemopoietic development in human embryos.

We report studies on hemopoietic progenitors and precursors in human embryos and fetuses at 4 to 5 through to 9 to 10 weeks from conception, as well as the corresponding in vivo Hb synthesis pattern. Particular attention is paid to the morphology of 5- to 8-week liver cells, as evaluated by both conventional and electron microscopy. On the basis of these observations, a unifying monoclonal model is proposed for human embryonic hemopoiesis.

Cells, Cultured↗
PubMed1982

Correlations between ancillary assays and bacteriuria in children with myelodysplasia and ileal conduit urinary diversions.

Urine from children with ileal conduit urinary diversions was assayed for antibody-coated bacteria, lysozyme and lactic dehydrogenase isoenzymes, and correlated with the results of quantitative urine culture. A significant proportion of the antibody-coated bacteria and lysozyme assays were positive when more than 10(4) organisms per ml. of urine were found. Lactic dehydrogenase isoenzyme results were frequently at variance with the other assay and culture results. Because none of the ancillary assays was invariably positive in patients with symptoms suggestive of upper tract disease, they remain imperfect research tools for localization of urinary tract infections in patients with ileal conduits. In this patient population quantitative urine culture remains the best clinical method for diagnosing urinary tract infections and evaluating the adequacy of antibiotic therapy. However, since the antibody-coated bacteria and lysozyme assays converted to negative with successful treatment, these tests may provide additional guidance to the physician in assessing the adequacy of treatment of urinary tract infections in patients with ileal conduit diversions.

Adolescent↗
PubMedDate not supplied

Restoration-related salivary Streptococcus mutans level: a dental caries risk factor?

OBJECTIVES: The salivary level of Streptococcus mutans related to filled teeth was compared with the levels related to decayed and sound teeth, in order to establish whether the presence of restorations may increase the risk of infection of other teeth by Streptococcus mutans. METHODS: The sound, decayed and filled teeth were recorded in 809, 6-7-year-old school-children. Salivary Streptococcus mutans detection (i.e. more than 1 x 10(4) CFU/ml) and counts were evaluated. Streptococcus mutans log count means and prevalence values of subjects with only sound teeth (group 1), with filled, without decayed teeth (group 2), with decayed, without filled teeth (group 3), were calculated and compared using the Student's t-test and the chi-square test. The effect of filled, decayed and sound teeth on Streptococcus mutans level was also evaluated using logistic regression. RESULTS: Log count means and prevalence values of group 2 subjects were significantly lower than values of group 3 subjects (means, 0.92 vs 1.66: prevalence, 73.17% vs 94.63%) and statistically not-different from values of group 1 subjects (mean. 0.75: prevalence, 70.06%). The logistic regression analysis showed that the factors significantly increasing the risk of Streptococcus mutans being detected in saliva were only primary and/or permanent decayed teeth. The risk of Streptococcus mutans being detected in saliva was not affected by filled teeth more than sound teeth. CONCLUSIONS: In the present study population, the salivary Streptococcus mutans level attributable to filled teeth was low; this suggests that treatment of a carious lesion would cause a lowering of Streptococcus mutans concentration to the same levels as those shown by healthy subjects, thus reducing the risk of infection to other teeth.

Child↗
PubMedDate not supplied

Haemoglobin switching in human embryos: asynchrony of zeta----alpha and epsilon----gamma-globin switches in primitive and definite erythropoietic lineage.

Haemoglobin switching in humans provides a unique model for investigating the mechanisms underlying expression of a developmentally regulated gene family. Numerous studies have focused on the switch from fetal to adult (that is, gamma----beta) globin, but little is known about the embryonic----fetal (that is, zeta----alpha and epsilon----gamma) switches, as well as the transition from 'primitive' yolk sac to 'definitive' liver erythropoiesis. Here we have studied the embryonic----fetal haemoglobin switches in yolk sac, liver and circulating blood erythroblasts from 25 embryos and 6 fetuses. Globin synthesis was also evaluated in purified 'primitive' and 'definitive' erythroblasts. Primitive erythroblasts synthesize essentially zeta and epsilon chains at 5 weeks and alpha- and epsilon-globin with a minor aliquot of zeta and gamma chains at 6-7 weeks, whereas definitive erythroblasts produce alpha and epsilon + gamma + beta-globin at 6 weeks but only alpha and gamma + beta chains from 8 weeks onward. In both lineages the zeta----alpha and the epsilon----gamma switches are asynchronous, the former preceding the latter. Furthermore, zeta- and beta-globin synthesis is restricted to primitive and definitive erythroblasts respectively. These findings are discussed in terms of a monoclonal model for haemoglobin switching in early human ontogeny.

Age Factors↗
PubMedDate not supplied

Caries prediction by multiple salivary mutans streptococcal counts in caries-free children with different levels of fluoride exposure, oral hygiene and sucrose intake.

The aims of this study were to assess whether multiple salivary mutans streptococcal (ms) counts have a higher predictive power than a single one, and whether the predictive power of the test is different at different levels of fluoride exposure, oral hygiene and sucrose consumption. Three salivary ms tests were performed at 3-month intervals (positive test: salivary ms >/=5x10(5) cfu/ml) on a sample of 304, initially caries-free, 6- to 7-year-olds. Plaque index was also assessed and the parents filled out a questionnaire concerning sucrose-containing eating events and fluoride exposure. Sensitivity, specificity and Youden's index (J) were used to compare the predictive power. Thirty-six percent of the children developed caries during the 2-year follow-up. The highest J value for a single ms test (the second) was 0.24 (sensitivity 29.1%, specificity 95.4%). The multiple ms test with the highest J value (0.29) was obtained by the dichotomies 0 vs. 1-3 positive tests (sensitivity 50.0%, specificity 79.9%) and 0-1 vs. 2-3 positive tests (sensitivity 31.8%, specificity 97.4%). The predictive power of the multiple test was passable for children with low fluoride exposure and high plaque index (sensitivity 57.4%, specificity 93.7%, J 0.51), while it was low for the other groups. Sucrose exposure did not significantly affect the predictive power of the ms test.sion.

Chi-Square Distribution↗