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Biomedical subjects

M Fontana

Publications and source records attributed to M Fontana.

At least 37 records · Page 2Linked to original sources
PubMed2000

An In vitro microbial-caries model used to study the efficacy of antibodies to Streptococcus mutans surface proteins in preventing dental caries.

The first step for a pathogenic bacterium to initiate infection is via attachment (i.e., through surface determinants) to a suitable receptor. An in vitro microbial artificial-mouth model was used to test the efficacy of polyclonal antibodies to Streptococcus mutans cell surface proteins (CsAb) and a cell surface 59-kDa protein (59Ab) in preventing S. mutans colonization and carious lesion formation. In study 1, groups of 12 human teeth specimens were inoculated with S. mutans, which were incubated with different concentrations of CsAb (A1 [positive control], sterile saline, no antibody; A2, 0.007 mg of antibody protein/ml; and A3, 0.7 mg of antibody protein/ml) for 1 h at 37 degrees C. The negative control group (B1) was not infected and was incubated with Trypticase soy broth (TSB) without dextrose supplemented with 5% sucrose (TSBS). In study 2, the same study design was used except that 59Ab was used instead of CsAb, normal rabbit serum was used in the positive control group (A1), and TSB supplemented with 1% glucose was used as the nutrient to control for sucrose-dependent colonization. All groups were exposed for 4 days to circulating cycles of TSBS and TSB (study 1 and study 2, respectively; 30 min each, three times per day) and a mineral washing solution (21 h per day). Prior to each nutrient cycle, 1 ml of the appropriate CsAb or 59Ab solution was administered to each group and allowed to mix for 30 min before cycling was resumed. Data obtained by confocal laser scanning microscopy demonstrated the presence of a significantly smaller (P < 0.05) lesion area and a smaller total lesion fluorescence in group A3 than in group A1 for both studies. In study 1, group A2 had significantly smaller values than A1 for lesion depth and area. There were no significant differences between groups A2 and A3 for lesion area or between groups A1 and A2 for total lesion fluorescence. In study 2, there were no significant differences among groups A1 and A2 for lesion depth or between groups A2 and A3 for all of the parameters studied. In both studies, there were no significant differences between S. mutans plaque CFU numbers among any of the groups. These studies demonstrated the efficacy of CsAb and 59Ab in reducing primary caries development in this model, although the underlying mechanism remains unclear.

Antibodies, Viral↗
PubMed2000

Secondary caries and restoration replacement: an unresolved problem.

This article reviews the prevalence and main causes of restoration failure and replacement. It then focuses on secondary caries, its histopathology, etiology, difficulties in diagnosis, and prevention and remineralization possibilities. This article concludes that although secondary caries is still the main reason for restoration replacement, the development of new technologies for detecting and monitoring these lesions at an early stage should allow for testing new interventions to arrest or remineralize these lesions, which would delay the need for re-restoration.

Anti-Infective Agents, Local↗
PubMed1999

Fluorescence properties of melanins from opioid peptides.

Recently our group synthesized a new class of melanins obtained by the tyrosinase-catalyzed oxidation of opioid peptides (opiomelanins). Owing to the presence of the peptide moiety such pigments exhibit high solubility in hydrophilic solvents, which allows spectroscopic investigations. In particular, the absence of solid-state quenching effects enables the study of melanin fluorescence properties, till now poorly investigated due to the complete insolubility of melanins produced from tyrosine or Dopa. Opiomelanins dissolved in aqueous medium show a characteristic emission peaked at 440 and 520 nm when excited around 330 nm, where a maximum is observed in the absorption spectrum. Kinetic measurements performed on the tyrosinase-catalyzed oxidation of opioid peptides show that the 440-nm fluorescence band arises in the early stages of peptide oxidation, whereas the 520-nm band appears in later stages of oxidation, i.e., during the polymerization of indole-quinone units. Moreover, molecular sieve fractionation shows that in the opiomelanin fraction with a molecular weight lower than 10 kDa the 440-nm band is dominant in the fluorescence spectrum. The breakdown of the polymer induced by hydrogen peroxide and light (i.e., the photobleaching of melanin pigments) produces a marked enhancement of the 440-nm fluorescence band while the 520-nm band disappears. Hence, our findings suggest that the observed fluorescence contains contributions from both oligomeric units (440-nm band) and high-molecular-weight polymers (520-nm band).

Agaricales↗
PubMed1999

Body composition in HIV-infected children: relations with disease progression and survival.

BACKGROUND: Malnutrition is common in HIV-infected children, but the body compartment that is most affected has been ill defined. OBJECTIVES: Our objectives were to 1) compare the fat-free mass (FFM) of children with HIV infection with that of control children, 2) assess the contribution of FFM to body weight in HIV-infected children compared with that of control children, and 3) study the relations between body weight, FFM, and mortality. DESIGN: A cross-sectional study was performed in 86 HIV-infected and 113 uninfected children (mean ages: 6.9 and 7.7 y, respectively). FFM was estimated from single-frequency bioelectrical impedance analysis by using 3 different published equations; a further estimate was obtained from triceps-skinfold-thickness measurements. RESULTS: All 4 estimates of body composition showed that FFM in HIV-infected children was significantly less than in control children of similar age. However, FFM as a percentage of body weight was not significantly different between groups. In the whole group of infected children, an age-specific z score < -2 for weight and for FFM was significantly associated with an increased risk of death [relative risk (95% CI) = 11.4 (3.1, 41.0) and 5.1 (1.5, 18.2), respectively]; when only children with more severe disease were considered, only z score for weight was significantly associated with an increased risk [4.6 (1.4, 14.9)]. CONCLUSIONS: These findings suggest that no preferential catabolism of FFM occurs in HIV-infected children and that body weight for age is a better prognostic indicator than is FFM estimated by bioelectrical impedance analysis.

Analysis of Variance↗
PubMed1999

Intranasal immunization against dental caries with a Streptococcus mutans-enriched fimbrial preparation.

Streptococcus mutans has been identified as the major etiological agent of human dental caries. The first step in the initiation of infection by this pathogenic bacterium is its attachment (i.e., through bacterial surface proteins such as glucosyltransferases, P1, glucan-binding proteins, and fimbriae) to a suitable receptor. It is hypothesized that a mucosal vaccine against a combination of S. mutans surface proteins would protect against dental caries by inducing specific salivary immunoglobulin A (IgA) antibodies which may reduce bacterial pathogenesis and adhesion to the tooth surface by affecting several adhesins simultaneously. Conventional Sprague-Dawley rats, infected with S. mutans at 18 to 20 days of age, were intranasally immunized with a mixture of S. mutans surface proteins, enriched for fimbriae and conjugated with cholera toxin B subunit (CTB) plus free cholera toxin (CT) at 13, 15, 22, 29, and 36 days of age (group A). Control rats were either not immunized (group B) or immunized with adjuvant alone (CTB and CT [group C]). At the termination of the study (when rats were 46 days of age), immunized animals (group A) had significantly (P < 0.05) higher salivary IgA and serum IgG antibody responses to the mixture of surface proteins and to whole bacterial cells than did the other two groups (B and C). No significant differences were found in the average numbers of recovered S. mutans cells among groups. However, statistically fewer smooth-surface enamel lesions (buccal and lingual) were detected in the immunized group than in the two other groups. Therefore, a mixture of S. mutans surface proteins, enriched with fimbria components, appears to be a promising immunogen candidate for a mucosal vaccine against dental caries.

Administration, Intranasal↗
PubMed1999

Oxygen uptake and cardiac performance in obese and normal subjects during exercise.

Work capacity and cardiopulmonary performance were studied in a group of 11 young obese subjects (BMI 39.9 kg/m2) and a group of 10 young normal subjects (BMI 22 kg/m2). First of all they underwent an incremental cycle ergometer test up to exhaustion. Subsequently, every subject of the two groups performed a constant work rate test at different work loads to estimate cardiac output (Q) below anaerobic threshold (AT) by a 20-second CO2 rebreathing method. Obese subjects had a significantly lower AT (79 vs. 109 W). The ratio between oxygen uptake and heart rate (VO2/HR) (O2 pulse) was higher in the obese group; nevertheless, this variable became significantly lower if we took into consideration the ratio between O2 pulse and kilogram fat-free body mass or kilogram body weight. Both these observations suggest that their reduced work tolerance is linked with a reduced oxygen supply to the muscles in activity. Q increased in similar ways in obese and normal subjects at the preset work rates. The ratio Q/body surface (cardiac index; CI) that we considered in order to try to minimize the differences in body sizes between the two groups, increased less in response to increasing work rates in our obese subjects than in normal subjects. As a whole, these data appear to be in line with a relatively less efficient cardiac performance during progressive work rates in obese subjects.

Adolescent↗
PubMed1999

Surgery aboard ship: is it safe?

A retrospective review was performed on 684 surgical procedures done aboard U.S. Atlantic Fleet ships during a 3-year period from 1994 to 1996. These procedures were compared with similar procedures performed at the Naval Medical Center in Portsmouth, Virginia. Morbidity and mortality rates were calculated and compared. A very low morbidity rate (0.43%) was reported for surgical procedures performed while deployed compared with 1.69% for procedures at the Naval Medical Center. One mortality was reported. These extremely low rates are felt to be attributable to multiple causes, including a highly selected, healthy patient population, performance of only low-risk procedures, early presentation of surgical problems, and early medical evacuation of patients with complex medical and surgical problems. We feel that elective surgical procedures such as vasectomy, circumcision, inguinal hernia repair, and hemorrhoidectomy can be performed safely aboard ship. This would increase the training opportunity for all members of the medical department and at the same time decrease the costs and risks associated with medical evacuation.

Cost Control↗
PubMed1998

Serum pancreatic enzymes in human immunodeficiency virus-infected children. A collaborative study of the Italian Society of Pediatric Gastroenterology and Hepatology.

BACKGROUND: Numerous studies have shown pancreatic disease in adult human immunodeficiency virus (HIV)-infected patients, but there are very few reports on pediatric patients. Our aim was to determine the prevalence of increased serum pancreatic enzyme levels and their relationship to clinical manifestations of acute pancreatitis in HIV-infected children. METHODS: Forty-seven consecutive, symptomatic HIV-infected children (24 male; median age, 7.3 years; range, 1-17 years) and 45 sex- and age-matched controls without gastroenterologic disease were enrolled. In all subjects serum total amylase, pancreatic amylase, and lipase were assayed with commercial kits. The following were recorded: disease progression (CDC class), nutritional status (weight Z-score), CD4 lymphocyte count, drug treatment during the previous 12 months, presence of opportunistic infections, clinical evidence of acute pancreatitis (increased serum pancreatic enzymes associated with vomiting, abdominal distention, and intolerance when eating). RESULTS: Ten of 47 HIV patients had increased serum total amylase values; however fewer patients had increased specific pancreatic enzymes: 6 of 47 for pancreatic amylase (range, 1.8- to 19.8-fold normal limit) and 7 of 47 for lipase (range, 1.4- to 4-fold normal limit). Values were normal in all controls. Two HIV patients with increased total amylase had clinically evident parotid inflammation. None of the patients with increased serum pancreatic amylase and/or lipase had clinical symptoms of acute pancreatitis. Regression analysis showed no correlation between increased serum pancreatic enzyme levels and disease progression (CDC class), immunologic status (CD4 count), nutritional status, drug administration, or opportunistic infections. CONCLUSIONS: Fifteen per cent of HIV-infected children had biochemical evidence of pancreatic involvement; however, this condition was unrelated to clinical signs of pancreatitis. Neither drug administration nor opportunistic infections seem to determine the increased serum pancreatic enzyme levels.

AIDS-Related Opportunistic Infections↗
PubMed1998

Antioxidant properties of the decarboxylated dimer of aminoethylcysteine ketimine: assessment of its ability to scavenge peroxynitrite.

The natural sulfur compound aminoethylcysteine ketimine decarboxylated dimer (AECK dimer) has been investigated for its ability to act as peroxynitrite scavenger. It has been found that the product efficiently protects against the nitration of tyrosine and the inactivation of alpha1-antiproteinase by peroxynitrite. The tyrosine nitration can be completely prevented by 100 microM AECK dimer which appears as effective as the antioxidants glutathione and N-acetylcysteine. The AECK dimer was also found to limit surface charge alteration of low density lipoprotein induced by peroxynitrite. These findings indicate that the AECK dimer is a strong protective agent against peroxynitrite damage and that it could play an important role in the defence against oxidative stress in human diseases.

Amino Acids, Sulfur↗
PubMed1998

Antioxidant activity of aminoethylcysteine ketimine decarboxylated dimer on copper-induced LDL oxidation.

Aminoethylcysteine ketimine decarboxylated dimer (AECK-DD), a member of a family of natural cyclic sulfur-containing aminoacids, recently detected in biological samples, protects low density lipoprotein (LDL) against copper-mediated oxidation, as assessed by monitoring the kinetics of conjugated diene formation, thiobarbituric acid-reactive substances production and LDL-tryptophan fluorescence quenching. Moreover, AECK-DD exerts a protective effect also against metal-independent, peroxyl radical-induced lipoprotein oxidation. It is of note that the concentrations exerting a protective effect against LDL oxidation are similar to those found in biological samples.

Amino Acids, Sulfur↗
PubMed1998

Pancreatic dysfunction and its association with fat malabsorption in HIV infected children.

BACKGROUND: Nutrient malabsorption frequently occurs in HIV infected children, but very few studies have investigated exocrine pancreatic digestive capacity in these cases. AIMS: To investigate pancreatic function in HIV infected children and to determine whether faecal fat loss, a prominent feature of intestinal dysfunction, is associated with pancreatic dysfunction. PATIENTS: Forty seven children with HIV infection without apparent pancreatic disease and 45 sex and age matched healthy controls. METHODS: Pancreatic function was evaluated by measuring elastase 1 concentration and chymotrypsin activity in stools by ELISA and colorimetric methods, respectively. Intestinal function was evaluated by measuring fat and protein loss by the steatocrit method and by faecal alpha1 antitrypsin concentration. RESULTS: 14 (30%) had abnormal pancreatic function tests: seven had isolated elastase activity deficiency, three isolated chymotrypsin deficiency, and four pancreatic deficiencies in both enzymes. Patient enzyme values were significantly lower than those of controls. Low faecal pancreatic enzymes were not associated with symptoms. Twelve children had steatorrhoea and four had increased alpha1 antitrypsin. Steatorrhoea was significantly associated with reduced faecal pancreatic enzymes. There was a significant negative correlation between elastase 1 concentration and steatocrit. Children with pathological faecal elastase 1 or chymotrypsin values did not differ from the other HIV infected children with respect to nutritional and immunological status, stage of HIV disease, presence of opportunistic infections, or drug administration. CONCLUSIONS: Abnormal pancreatic function tests are a frequent feature of paediatric HIV infection; this condition is associated with steatorrhoea, which probably contributes to the disease.

Adolescent↗
PubMed1998

Measurement of enamel remineralization using microradiography and confocal microscopy. A correlational study.

Tooth minerals are lost and regained constantly in a normal, human oral environment. Different methods have been developed to measure this gain and loss in enamel minerals; however, these methods deal with different problems, such as being time consuming or involving the use of X-rays. The aim of this study was to determine if remineralization measured in a thin enamel section (TS) by transversal microradiography (MR) can be reliably monitored by measuring lesion parameters (area, total and average dye fluorescence) on the same TS or on half a tooth (HT) with confocal laser scanning microscopy (CLSM). Thirty-six human enamel specimens were demineralized for 96h, and then half of each specimen was covered with an acid-resistant nail varnish. Specimens were divided into three groups (12/group) and subjected for 20 days to a cyclic remineralization regimen with consisted daily of a 4-hour acid challenge, four 1-min treatment periods with 0, 250 or 1,100 ppm F dentifrice slurries (1:2; dentifrice:water) and 20 h in pooled, human saliva, at room temperature. Specimens were cut and analyzed by MR, then stained with a fluorescent dye (0.1mM rhodamine B) for 1 h and analyzed using CLSM. Both MR and CLSM detected significantly greater remineralization (p<0.05) in the specimens treated with the fluoride-containing dentifrices than in the specimens treated with 0 ppm F. Significant differences were detected between specimens treated witht the fluoride-containing dentifrices by MR and CLSM (HT area and total fluorescence). Statistically significant (p<0.05) Pearson correlation coefficients were calculated between the MR and CLSM data: difference in MR mineral content (DeltaM) versus HT lesion area = 0.71; DeltaM versus HT total fluorescence = 0.70; DeltaM versus HT average fluorescence = 0.61; DeltaM versus TS lesion area = 0.88; DeltaM versus TS total fluorescence = 0.63, and DeltaM versus TS average fluorescence = 0.40. It is concluded that confocal microscopy in either TS or HT may provide valid surrogates (area and total fluorescence) for MR measurements in enamel remineralization studies.

Analysis of Variance↗
PubMed1998

Intracavitary chemotherapy with thiotepa in malignant pericardial effusions: an active and well-tolerated regimen.

PURPOSE: Malignant pericardial effusion, although highly variable, is an uncommon complication of cancer. It is often associated with symptoms like dyspnea, chest pain, and cough, which may be severe and disabling. We analyzed the results of our current treatment policy to evaluate the effectiveness and tolerance of a new approach for this disorder. PATIENTS AND METHODS: Patients with malignant pericardial effusions were treated with intracavitary thiotepa (15 mg on days 1, 3, and 5) through an indwelling pericardial cannula after extraction of as much pericardial fluid as possible on day 0. Responses were assessed by clinical examination, computed tomographic (CT) scan, and echocardiography before treatment, 1 month after treatment, and every 2 months thereafter. Twenty-three patients with malignant symptomatic pericardial effusion were treated and all were assessable for effectiveness and tolerance of the procedure. RESULTS: Nine patients with breast cancer, 11 with lung cancer, two with an unknown primary tumor, and one with metastatic melanoma were treated. In all but three patients, systemic medical treatment was started after completion of intracavitary therapy. Nineteen patients responded to treatment (83%; 95% confidence interval, 61% to 95%) with a rapid improvement of symptoms. The median time to pericardial effusion progression was 8.9 months (range, 1 to 26). No significant side effects were registered, except one patient who had transient grade III thrombocytopenia and leukopenia and one patient who had grade I leukopenia. CONCLUSION: A short course of intracavitary treatment with thiotepa is highly effective and well tolerated in the treatment of malignant pericardial effusion.

Adult↗
PubMed1998

A comparative analysis of integrating visual representations with haptic displays.

As further advances in visual display technologies and force feedback devices are integrated in virtual systems, questions remain: What level of reality does the system provide to the user? Is the environment convincing enough to engage the user and to maximize transfer? Are the visual and haptic displays fully integrated to provide seamless operation in the simulated environment? Does the system provide not only the ability to navigate through a simulated environment, but also realistic interaction with instrumentation and structures? We report on our advances in developing a virtual simulation system for training in functional endoscopic sinus surgery (FESS). Specifically, we will present work on subject trials exploring the realism provided by integrated visual and haptic displays, and compare and contrast surface vs. volume representation for presenting realistic models of the anatomy for surgical interaction.

Computer Simulation↗
PubMed1998

[Aspergillosis of the paranasal sinuses].

Because of the shortage of rhinosinusal aspergillosis cases, as the reported here, we think this article might be of interest. The lesion, localized in maxillary sinus, triggered a reactive pansinusitis, afebrile and void of general impact. Description of our way to attend the case, the procedure to achieve the diagnosis and differential diagnosis as well. Bibliographical references.

Adult↗