Characterization of the radiation beam of a tomotherapy equipment with MCNP.

This work aims to model and characterize the radiation beam of one Accuray tomotherapy equipment using the Monte Carlo Code MCNP5 (Monte Carlo N-Particle). This tomotherapy equipment is used for delivering high doses of radiation in tumor regions to kill cancer cells and shrink the tumor during radiation therapy of cancer patients, however, the radiation can damage surrounding areas and nearby organs at risk (OAR) if the radiation field is not well delimited. In particular, intensity-modulated radiotherapy treatments (IMRT) with tomotherapy equipment offer great benefits to patients allowing treatment of tumor regions without affecting surrounding areas and OAR. Nowadays, it is well known that a correct simulation of transport of radiation in tomotherapy equipment facilitates considerably the estimation of ideal doses in the tumor, surrounding regions, and OAR. For that reason, in this work, we simulated the geometry of the 6 MV ACCURAY Tomotherapy equipment of the CECAN using the MCNP5. The model includes a TomoLINAC consisting of an electron source that emits Gaussian distribution particles with an average energy of 5.7 MeV and width of 0.3 MeV. The emitted particles impact the tungsten target and pass through primary collimators and jaws that define the irradiation field in the isocenter. To validate the geometry and radiation transport in the TomoLINAC the curves of depth dose percentage (PDD) estimated by simulation and the curves measured experimentally were tuned. In the same way, the simulated transverse and longitudinal profiles were compared with the experimental results. In addition, a comparison between the qualities of the radiation beam characterized with MCNP and measured experimentally in CECAN showed a deviation of 1%. For the simulations, cylindrical detectors located inside a water phantom were considered and it was employed the tally *F8. A good agreement was observed between the PDD's curves obtained from the simulation and those measured experimentally for a field of 5 × 10 cm2 in the isocenter and SSD (distance from the source to the surface) of 85 cm. Also, the comparison between the simulated and experimental transverse profiles obtained at 1.5 cm, 10 cm and 15 cm depth with a radiation field of 5 × 40 cm2 showed very good agreement. The longitudinal profiles were estimated with the same depths as the transverse ones, but for each of them, the openings of the jaws were 5.0 cm, 2.5 cm and 1.0 cm in the longitudinal direction, which corresponds to the direction in which the patient's table moves. The comparison between the simulated and experimental longitudinal profiles showed good concordance too. Once the radiation beam of the ACCURAY tomotherapy equipment had been characterized, experimental dose measurements were made using a Cheese phantom and two A1SL ionization chambers. These results obtained experimentally were compared with those estimated with MCNP for a field of 5 × 40 cm2 at the isocenter and SAD of 85 cm and, it was concluded that both results were similar considering the regions of uncertainty. Finally, we must highlight that the modeling and characterization of the radiation beam of CECAN's ACCURAY tomotherapy equipment can be a key tool for dose estimations in different cancer treatment plans and future research.

Fluorescent organic particle doped polymer-based gel dosimeter for neutron detection.

The purpose of this work is to develop a material capable of detecting neutrons produced by photodisintegration in a linear accelerator for its medical use. In this study, we have developed a gel-like material doped with fluorescent organic particles. PPO at 1 wt% is used as primary dopant and POPOP as secondary one at 0.03 wt%. A set of four samples is produced, with boric acid concentrations of 0, 400, 800 and 1200 ppm. The viscoelastic properties of the material are characterized with rheological measurements, finding a gel-like behavior, i.e., a material that can keep its original shape if no stresses are applied, but can also be deformed by applying a moderate shear rate. Furthermore, the material was irradiated with gamma, electron, and neutron emission sources from 137Cs, 22Na, 60Co, 210Po, 90Sr and 241AmBe, and its response was measured in two different experimental settings, in two different institutions, for comparative purposes. From these measurements, one can clearly establish that the new material detects neutrons, electrons, and gammas within the MeV regions and below. Thus, our findings show that the developed material and its properties make it a promising technology for its use in a neutron detector.

COMT rs4818, pain sensitivity and duration, and alveolar bone grafting of oral clefts.

PURPOSE: Verifying whether the mutation in COMT rs4818 could be involved in pain modulation. METHODS: Thirty-two individuals born with cleft lip and palate that underwent bone graft from the iliac crest bone were assessed at 12, 24, 48, 72 h, and 7 days regarding their pain experience using a visual analogic scale. DNA from each participant was collected from saliva samples, and genotyping of rs4818 was performed using TaqMan chemistry. Overrepresentation of rs4818 alleles was tested using chi-square or Fisher's exact tests with an alpha of 0.05. RESULTS: Of the 32 individuals, eighteen reported long pain duration, nine reported high pain intensity, and fourteen low pain intensity up to 48 h. No differences were found in the distribution of individuals depending on the reported pain by sex (p = 0.12), age (p = 0.42), or cleft type (p = 0.5). The distribution of COMT r4818 alleles was different depending on the intensity and duration of pain. Carriers of the C wild-type allele were four times more likely to show high pain intensity and duration (odds ratio = 4.29, 95% confidence interval 1.13-16.18), meaning that the G variant allele is protective. CONCLUSION: COMT rs4818 is associated with postoperative pain after alveolar bone grafting.

Heyde syndrome in a 71-year-old man who underwent chest radiotherapy at young age.

We report the case of a 71-year-old man with diagnosis of aortic valve stenosis for ten years, who came to hospital because of breathlessness during the previous two months and recent low intestinal hemorrhage. On admission, laboratory tests and upper gastrointestinal endoscopy and colonoscopy revealed anemia and bleeding cecal angiodysplasia. The echocardiography study showed a severe aortic stenosis. Classical Heyde syndrome is described as the association of aortic stenosis, bleeding gastrointestinal angiodysplasia and secondary anemia. The antecedent of mediastinal radiotherapy for treatment of Hodgkin's disease during his youth, and eventual late cardiac adverse effects that may include aortic or mitral valve disturbances are highlighted. Electrocoagulation with argonium was performed on the sites of active bleeding during the colonoscopy. In sequence, surgical replacement by bioprothesis was done on the aortic valve. The patient remains asymptomatic, under long-term outpatient surveillance, with normal control evaluations. The aim of this case study is to emphasize difficulties related to diagnosis, and to highlight the role of endoscopy and imaging studies to confirm a hypothesis of this underestimated condition.

Antimicrobial effects of the combination of chlorhexidine and xylitol.

AIMS: To assess the effect of combining 1% chlorhexidine varnish (CHX) with xylitol chewing gum (XYL) on Streptococcus mutans and biofilm levels in 6-8-year-old children. DESIGN: Randomised controlled study. SUBJECTS AND METHODS: Eighty-two 6-8-year-old children were randomly divided into groups as follows: G1 (n = 20): xylitol chewing gum twice a day after breakfast and lunch; G2 (n = 20): xylitol gum as G1 plus chlorhexidine varnish application at the start of the study and after one and two months; G3 (n = 20): chlorhexidine varnish as G2; and G4 (n = 22): fluoride gel application at the start of the study and after one and two months. Microbiological tests were performed to assess Streptococcus mutans colony forming units (CFU) and the teeth of those children with moderate or higher CFU scores were examined for visible biofilm. CFU scores were categorised as follows: 0 = absence of S. mutans, 1 = low level (1-10 CFU), 2 = moderate level (11-100 CFU), 3 = high level (101-250 CFU), 4 = very high level (>250 CFU). Biofilm scores based on a scale from 0 (absence of biofilm) to 5 (thick biofilm firmly adhered to posterior and anterior teeth) were obtained. RESULTS: The biofilm reduction was greater in G2 and G3, with mean values of 3.38 and 3.17 to 1.79 and 1.88, respectively (p <0.05). All groups presented a reduction in the S. mutans levels. XYL + CHX showed the largest reduction throughout the study period, with 58.3% in the first month, 84.2% in the second and 92.9% at the end of the study. CONCLUSIONS: The XYL + CHX combination was efficient and superior to single treatments in controlling biofilm and suppressing S. mutans.

Corporoplasty using bovine pericardium grafts in complex penile prosthesis implantation surgery.

PURPOSE: This paper is the first, to our knowledge, to propose the use of a bovine pericardium graft in corporoplasty for penile prosthesis implantation. The advantages of bovine pericardium graft have been demonstrated by its use in cardiac surgery, including low cost, biocompatibility, impermeability, resistance to dilatation, flexibility, low likelihood of retraction, absence of antigenic reaction and natural absorption of the tissue. In this paper, we propose the use of this heterologous material graft in corporoplasty for penile prosthesis implantation. MATERIALS AND METHODS: Five patients with a history of erosion, infection and fibrosis, mean time of follow-up 32 months (range 9-48 months). Bovine pericardium was used to cover large areas of implanted penile prostheses when use of the tunica albuginea was unfeasible. RESULTS: The surgical procedure resulted in no complications in all patients. CONCLUSIONS: Bovine pericardium may substitute synthetic and autologous material with the additional advantages of lower cost and greater availability.

Corporoplasty using bovine pericardium grafts in complex penile prosthesis implantation surgery

Purpose: This paper is the first, to our knowledge, to propose the use of a bovine pericardium graft in corporoplasty for penile prosthesis implantation. The advantages of bovine pericardium graft have been demonstrated by its use in cardiac surgery, including low cost, biocompatibility, impermeability, resistance to dilatation, flexibility, low likelihood of retraction, absence of antigenic reaction and natural absorption of the tissue. In this paper, we propose the use of this heterologous material graft in corporoplasty for penile prosthesis implantation. Materials and Methods: Five patients with a history of erosion, infection and fibrosis, mean time of follow-up 32 months (range 9-48 months). Bovine pericardium was used to cover large areas of implanted penile prostheses when use of the tunica albuginea was unfeasible. Results: The surgical procedure resulted in no complications in all patients. Conclusions: Bovine pericardium may substitute synthetic and autologous material with the additional advantages of lower cost and greater availability.

Contractilidad del músculo ventricular bajo la acción de prajmalina-propanolol y prajmalina-epinefrina / Contractibility of the ventricular muscle under the action of prajmaline-propanolol and prajmaline-epinephrine

Los efectos de la estimulación adrenérgica alfa y beta, pueden ser logrados por agentes agonistas y antagonistas, como la epinefrina y el propranolol respectivamente. Con el objetivo de precisar aspectos relacionados con la contractilidad del músculo ventricular, se realizaron un total de trece experimentos utilizando combinaciones de prajmalina-epinefrina y prajmalina-propanolol, prefundiendo preparaciones de tiras de músculo ventricular de trece ejemplares adultos de ranas catesbeiana. La prajmalina, antiarrítmico del grupo I, se obtuvo a partir de la Rauvvolfia viridis, planta endémica de Cuba. Las preparaciones fueron estimuladas con pulsos de corriente, y la tensión desarrollada por el músculo fue registrada por un transductor fuerza-desplazamiento. Las señales eléctricas fueron convertidas en trazos por un equipo registrador. Los resultados indican que las combinaciones de prajmalina-epinefrina y prajmanina-propanolol afectan de forma diametralmente opuesta la contractilidad del músculo cardíaco, aumentando en un 40% y disminuyendo en un 15% respectivamente la fuerza de la contracción del músculo ventricular. Por otra parte se sugiere un posible mecanismo de acción de la prajmalina sobre los receptores alfa presentes en las membranas de las células ventriculares.

The effects of alfa and beta adrenergic stimulation can be accomplished by agonist and antagonist agents such as epinephrine and propanolol respectively. Aimed at determining the aspects related to contractibility of ventricular muscle, thirteen experiments were performed using combinations of prajmaline "epinephrine and prajmaline" propanolol, being perfused preparations of ventricular muscle strips of thirteen samples of adult Catesblian frogs. Prajmaline, a group I antiarrhythmic, was obtained from Rauvvolfia viridis, an endemic plant in Cuba. The preparations were stimulated with electric current pulses and the tension performed by the muscle was registered by a force "displacement transductor". The electric signals were transformed into lines by a registering equipment. The results suggest that prajmaline "epinephrine and prajmaline" propanolol combinations affect diametrically opposed to contractibility of cardiac muscle, increasing by 40 % and decreasing by 15 %, respectively, the force of contraction of ventricular muscle. Alternatively, a potential mechanism of prajmaline action is suggested on alfa receptors present in the ventricular cell membranes.

Effects of solutions used in infants' oral hygiene on biofilms and oral microorganisms.

The purpose of this work was to evaluate the effects of oral hygiene solutions used for infants on biofilms formed in vitro from infants' saliva and dental plaque: ATCC reference strains A. viscosus; C. albicans; L. casei; S. mitis; S. mutans; S. oralis; S. sanguis; S. sobrinus and clinically isolated microorganisms (saliva) C. albicans, S. mitis, S. mutans, S. oralis, S. sanguis and S. sobrinus. After exposure of the oral biofilms to H2O2 diluted 1/4 to 1/16; and NaF 0.02 percent, concentrated and diluted 1/2, for 1 and 3 minutes, the viable count of microorganisms, compared to the controls was significantly reduced (p < 0.05). They also showed a significant antimicrobial effect for all the microorganisms evaluated, when compared to the control (p < 0.05). Exposure to sodium bicarbonate solution and a camomile solution, for 1 and 3 minutes, was not significantly lethal to oral biofilms nor to any microorganism evaluated, regardless of whether they were concentrated or diluted. We do not recommend the use of H2O2 but suggest using the camomile solution and NaF 0.02 percent in a rational manner for cleaning the infant's mouth.

Pacifier-sucking associated with a bizarre habit: a case report.

A case of a child, who used the pacifier with an uncommon habit is presented. She pulled out the hair on the right side of her head after rolling it round the base of the pacifier. She then sucked it and swallowed it. Based on this report the authors are emphasizing the importance of accompanying the orofacial development of the child as from its first year of life.

Effects of three different infant dentifrices on biofilms and oral microorganisms.

The purpose of this work was to evaluate the effects of infant dentifrices: A--with lactoperoxidase, glucose oxidase and lactoferrin; B--with 1100 ppm of NaF and sodium lauryl sulfate; C--with extract of calendula. The dentifrices were test on biofilms formed in vitro from saliva and dental plaque of infants, using reference strains A. viscosus (ATCC 43146); C. albicans (ATCC 51501); L. casei (ATCC 4646); S. mitis (ATCC 49456); S. mutans (ATCC 25175); S. oralis (ATCC 35037); S. sanguis (ATCC 10586); S. sobrinus (ATCC 27609) and isolated clinically microorganisms C. albicans, S. mitis, S. mutans, S. oralis, S. sanguis, S. sobrinus and Lactobacillus sp. Twenty infants were chosen, who were beginning treatment at the Infants Clinic of the Pediatric Dentistry Department, Federal University of Rio de Janeiro. A pool of unstimulated saliva and a pool of dental plaque were collected from which biofilms were produced. Supernatants from each dentifrice were prepared and concentrated and diluted solutions of the dentifrices and a control sterile diluent were tested against the biofilms produced, for 1 and 3 minutes, and against the microorganisms. The results were statistically analyzed by the ANOVA and Tukey Test. After the exposure of the biofilms produced both from saliva and from dental plaque, to the dentifrice B concentrated and 1/2, for 1 and 3 minutes, the viable microorganisms count (CFU/ml), compared to the controls, was significantly reduced (p < 0.05). However, exposure to the dentifrices A and C concentrated and dentifrice B 1/4 and 1/8, for 1 and 3 minutes, was not significantly lethal to the biofilms. The dentifrices A and C, either concentrated or diluted (1/2 to 1/128) and the dentifrice B in the dilutions 1/16 to 1/128 did not have an antimicrobial effect on any microorganism evaluated. For all the microorganisms evaluated, the dentifrice B concentrated and in the 1/2 dilution showed a significant antimicrobial effect, when compared with the control (p < 0.05).

Formation of alkali-soluble fluoride on the surface of human dental enamel after treatment with fluoridated gels: influence of the pH variation and of the treatment time.

The aim of this study was to quantify, in vitro, the formation of CaF2 after the application of three fluoridated gels: one neutral, one acidulated and another highly acidulated, on a bovine enamel dental surface treated with a Dijkman's demineralizing solution (1990). 145 sections were utilized, obtained from 145 sound teeth and divided into seven groups: C (enamel without treatment); FN1 (enamel demineralized and treated with neutral gel for 1 minute); FN4 (enamel demineralized and treated with neutral gel for 4 minutes); FFA1 (enamel demineralized and treated with acidulated gel for 1 minute); FFA4 (enamel demineralized and treated with acidulated gel for 4 minutes); FAA1 (enamel demineralized and treated with highly acidulated gel for 1 minute) and FAA4 (enamel demineralized and treated with highly acidulated gel for 4 minutes). The formation of CaF2 was analyzed by SEM and chemically by Caslavska's method (1975). The average and standard deviations from the groups studied were respectively: C-0.63; 0.38; FN1-23.06; 16.52; FFA1-54.11; 49.00; FAA1-43.87; 32.66; FN4-34.92; 23.00; FFA4-67.91; 42.36; FAA4-56.03; 38.96. (Mann-Whitney non-parametric test). The time of application did not interfere in the CaF2 formation from the acidulated and highly-acidulated gels. A minor concentration of fluoride and amount of pH from highly-acidulated gel did not affect the higher formation from the CaF2 in relation to the acidulated gel in both cases when the application was evaluated.

Craniometaphyseal dysplasia: case report.

Craniometaphyseal dysplasia is a rare genetic bone remodeling disorder characterized by undertubulation of the long bones, especially in the lower extremities, causing deformities of the metaphyses of the long bones, and sclerosis of the skull base or cranial bone hyperostosis. The authors report a case of craniometaphyseal dysplasia in an 8-year-old Brazilian child, emphasizing the importance of precocious diagnosis of this rare genetic disorder.

Fluoride uptake and release by composites and glass ionomers in a high caries challenge situation.

PURPOSE: To evaluate the behavior of composite resins and glass ionomer cements with regard to the uptake and release of fluoride, in a high caries challenge situation. MATERIALS AND METHODS: Standard test specimens of glass ionomer cement (Chelon Fil), a resin-modified glass ionomer (Vitremer), two polyacid-modified composite resins (VariGlass and Dyract) and a composite resin (Heliomolar), were submitted for 14 days to demineralization and remineralization cycles in order to simulate a high caries challenge, while from the eighth day onward, a fluoridated dentifrice solution was applied for 5 minutes twice a day and the daily fluoride release of those materials to the mediums was quantified and compared. Fifteen test specimens were prepared for each material, making up a total of 75. RESULTS: All materials studied, except for Heliomolar from day 4 to day 7 in the demineralizing solution, were capable of releasing fluoride in measurable quantities during the whole experiment. The fluoride amounts released by Chelon Fil, Vitremer, VariGlass and Dyract were significantly higher in the demineralizing solution (ANOVA, P < 0.05) than in the remineralizing solution, during almost the entire experiment. The fluoride amounts released by Heliomolar were significantly higher in the remineralizing solution (ANOVA, P < 0.05) than in the demineralizing solution, during almost the entire experiment. All materials studied were capable of uptaking fluoride from the dentifrice solution and of later releasing it to the solution, maintaining the release relatively constant and at a higher level than that seen between days 5 and 7.

Hypomaturation amelogenesis imperfecta: account of a family with an X-linked inheritance pattern.

Amelogenesis imperfecta (AI) is a heterogeneous genetic disorder which affects the dental enamel. It can have an autosomal dominant, autosomal recessive or X-linked pattern. The authors describe a case of a family with hypomaturation X-linked AI and discuss the clinical and histopathological aspects of this disorder.

Gingival status of HIV+ children and the correlation with caries incidence and immunologic profile.

PURPOSE: The aim of this study was to determine gingival health and caries levels in HIV-infected children. METHODS: The modified gingival index (GI) of 43 HIV+ children of both sexes, aged between 2 and 12 years, was measured and correlated with the DMFT/dmf. The children's immunodeficiency level was also established by means of the CD4:CD8 ratio. Pearson's product-moment correlation co-efficient and the Mann-Whitney U test were used. RESULTS: The GI was significantly related to the DMFT/dmf. The children with a GI = 0 presented significantly more DMFT/dmf than the children with a GI > or = 0.1, but there were no significant differences between the GIs of caries-free children and those with DMFT/dmf > or = 1. The children who presented a CD4:CD8 > or = 0.5 ratio presented less DMFT/dmf compared with children who presented a CD4:CD8 < 0.5 ratio. The children who presented a CD4:CD8 < 0.5 ratio presented a statistically significant correlation between their GI and their DMFT/dmf, unlike children who presented a CD4:CD8 > or = 0.5 ratio. Children with a CD4:CD8 < 0.5 who showed a greater DMFT/dmf index also showed greater gingival inflammation. CONCLUSIONS: In this study, children with greater caries experience showed more gingival inflammation. In addition, a greater immunological deficiency might indicate a greater caries experience in children.

VariGlass fluoride release and uptake by an adjacent tooth.

PURPOSE: To quantitatively analyze in vitro the fluoride release from proximal VariGlass restorations and resulting uptake by the enamel of adjacent teeth. MATERIALS AND METHODS: Sixty impacted third molars were used and assigned to three groups: C: control, teeth without restorations; RC: teeth with resin composite restorations (Prisma APH); and PMRC: teeth with polyacid-modified resin composite restorations (VariGlass). Each group consisted of four sets of five teeth each. In the latter two sets, by alternating restored and unrestored teeth, the proximal surfaces of three unrestored teeth with an area of exposed enamel were in contact with the restored proximal surfaces of two other teeth. The sets were submitted to high caries challenge conditions with demineralizing and remineralizing solutions for 14 days. The fluoride of each solution and the fluoride uptake were determined and statistical analyses were carried out (ANOVA and Tukey's test). RESULTS: The highest mean fluoride concentration occurred with Group PMRC in both kinds of solutions (P < 0.01), but this value was higher in the demineralizing solution (P < 0.01). Over the 14 days, however, this mean gradually decreased in both solutions (P < 0.01). Group PMRC also showed the highest mean fluoride uptake (P < 0.01), which gradually decreased with depth in the enamel (P < 0.01).

Fluoride uptake in situ after the use of dental floss with fluoride.

The possibility of having a commercial product such as waxed floss with an additional agent for controlling and preventing caries is promising. The aim of this research was to determine the uptake of fluoride on tooth enamel in situ after the utilization of a dental floss with fluoride incorporated into the wax. One hundred blocks of bovine enamel were artificially demineralized and randomly separated into a Control Group (C) and a Test Group (T). The dental blocks in group T were mounted two-by-two simulating proximal contacts and were fixed into intra-oral lower arch devices. Eight volunteers with a similar salivary flow and buffer capacity wore devices with the enamel blocks for eight days. During this period of time the subjects applied a 25 cm long portion of a mint waxed floss with fluoride (0.15 mgF/m, Oral-B) between the blocks, 3 times a day for 2 minutes after each meal. At the same time, brushing was carried out with a fluoride-free toothpaste. The alkali-soluble fluoride (CaF2) formed on the enamel was extracted using the Caslavska et al. method and measured with the Orion 96-09 electrode-specific and the EA 720 ion analyzer. The results showed that the group that had the most CaF2 on the enamel (median, minimum and maximum in microF/cm2) was Group T (3.00, 2.11 and 4.00), which differed significantly (p < 0.01) from group C (0.26, 0.10 and 0.69). It was concluded that fluoride uptake on enamel was 11.54 times higher after use of dental floss with fluoride in this study.

[Fragile X Syndrome: case report in two brothers]. / Síndrome do X frágil: relato de caso em dois irmãos.

OBJECTIVE: To alert the pediatricians about the phenotype of the patients with Fragile X Syndrome, because of it's high incidence and the variable degrees of incapacity that may occur. METHODS: Case report of two brothers with the classical findings of the Fragile X Syndrome (mental retardation, "Dumbo-like" ears, macroorchidism, among others), confirmed by cytogenetic studies. RESULTS: The diagnosis of the syndrome is based on the presence of a variable number of cells with fragile sites on the X chromosome at Xq 27.3. The DNA analysis revealed Fragile X locus in 14% of the brothers' metaphases and in 1% of the mother's. It was also observed that two cousins on the mother's side had the syndrome, confirmed by genetic studies. CONCLUSIONS: The recognition of this syndrome by the pediatrician is of extreme importance to an early multidisciplinary approach.

Dentinogenesis imperfecta type II: case report.

A case of dentinogenesis imperfecta type II is described. The authors also present a brief literature review and focus on the difficulty in treating such cases.