Crestal module design optimization of dental implants: finite element analysis and in vivo studies.

The aim of this study was to evaluate the biomechanical behavior of Bone Level dental implants with four different neck designs in contact with cortical bone. Numerical simulations were performed using a Finite Element Method (FEM) based-model. In order to verify the FEM model, the in silico results were compared with the results obtained from histological analysis performed in an in vivo study with New Zealand rabbits. FEM was performed using a computerized 3D model of Bone Level dental implants inserted in the lower jaw bone with an applied axial load of 100 N. The analysis was performed using four different implant neck designs: even surfaced, screwed, three-ring design and four-ring design. Interface are of bone growth was evaluated by analyzing the Bone-Implant-Contact (BIC) parameter obtained from in vivo histological process and analyzed by Scanning Electron Microscopy (SEM). Bone Level implants were inserted in the rabbit tibia, placing two implants per tibia. The BIC was evaluated after three and six weeks of implantation. FEM studies showed that the three-ring design presented lower values of stress distribution compared to the other studied designs. The lower levels of mechanical stress were then correlated with the in vivo studies, showing that the three-ring design presented the highest BIC value after 3 and 6 weeks of implantation. In silico and in vivo results both concluded that the implants with three-ring neck design presented the best biomechanical and histological behavior in terms of new bone formation, enhanced mechanical stability and optimum osseointegration.

Frequency of dental caries in active and inactive systemic lupus erythematous patients: salivary and bacterial factors.

OBJECTIVE: The objective of this study was to determine dental caries frequency and to analyze salivary and bacterial factors associated with active and inactive systemic lupus erythematous (SLE) patients. Also, a proposal to identify dental caries by a surface, teeth, and the patient was developed. MATERIAL AND METHODS: A cross-sectional, blinded study that included 60 SLE patients divided into two groups of 30 subjects each, according to the Activity Index for Diagnosis of Systemic Lupus Erythematous (SLEDAI). The decayed, missing, and filled teeth (DMFT) index and Integrative Dental Caries Index (IDCI) were used for analyzing dental caries. The saliva variables recorded were: flow, pH, and buffer capacity. The DNA copies of Streptococcus mutans and Streptococcus sobrinus were estimated by real-time PCR. RESULTS: The caries frequency was 85% for SLE subjects (73.3% for inactive systemic lupus erythematous (ISLE) and 100% for active systemic lupus erythematous (ASLE)); DMFT for the SLE group was 12.6 ± 5.7 and the IDCI was (9.8 ± 5.9). The ASLE group showed a salivary flow of 0.65 compared with 0.97 ml/1 min from the ISLE group; all variables mentioned above showed a statistical difference (p < 0.05). The salivary pH was 4.6 (6.06 for ISLE and 3.9 for ASLE). The DNA copies of S. mutans and S. sobrinus were high; all variables mentioned above show a significant statistical difference (p < 0.05) between groups. CONCLUSION: SLE patients had high DMFT and IDCI scores that were associated with a decrease in salivary flow, pH, and buffer capacity. There were high counts of S. sobrinus and S. mutans species, and IDCI is a useful tool to provide more detail about dental caries in epidemiological studies.

Hidden sources of mercury in clinical laboratories.

The healthcare sector is an important contributor to mercury (Hg) pollution because of the potential presence of mercury in thermometers, blood pressure cuffs, amalgams, etc. There are also other potential sources of mercury in this sector which are used frequently and in high volumes where the presence of the metal is not obvious and which might be collectively contributing to pollution. For instance, some chemicals used for the clinical diagnosis of illness may contain mercury. The goal of this study was to investigate potential sources of mercury pollution, which originate from clinical laboratory discharges, using an exploratory approach. The focus was on the residue generated during automatic analysis of patients' bodily fluids at a medical center in Hermosillo, Sonora, Mexico. This study shows an overview of what might be happening in the region or the country related to non-obvious sources of mercury in the healthcare sector. The results showed measurable levels of mercury in the residues coming from urine sediment analysis. These amounts do not exceed the maximum allowed by Mexican environmental regulations; nevertheless, the frequency and cumulative volume of residues generated, combined with the potential for persistence and the bioaccumulation of mercury in the environment, warrant attention. The work carried out in this study is being taken as a model for future studies for pollution prevention in the healthcare sector with the goal of measuring mercury emissions to the environment from clinical laboratory wastewater, including identifying sources which--while not obvious--could be important given the frequency and volume of their use in the clinical diagnosis.

Bioerosion caused by the sea urchin Diadema Mexicanum (Echinodermata: Echinoidea) at Bahías de Huatulco, Western Mexico

Mexican Pacific sea urchin studies have been focused mainly on species distribution, ecology and fisheries. Reef degradation by sea urchin bioerosion has not been studied previously en these reefs. We investigate the importance of Diadema mexicanum as a bioerosive agent of coral carbonate at Bahias de Huatulco, and the relative magnitude of coral accretion and bioerosion. At each of five localities in Bahias de Huatulco, sea urchin density, feeding and mechanical (spine) erosion was determined for three size class intervals. In general, D. mexicanum do not exert any significant role on coral reef community structure (live coral, dead coral or algal coverage) at the Huatulco area, probably because they are generally small (2.9-4 cm test size) and few in number (1.0-6.8 ind.m-2). Mean bioerosion rates are consistent with those measured for other diadematoids, as well as other urchin species in various eastern Pacific localities. However, the degree of bioerosive impact depends on species, test size, and population density of urchins. Coral carbonate removal by D. mexicanum erosion varies from 0.17 to 3.28 kgCaCO3m(-2)yr(-1). This represents a carbonate loss of < 5% of the annual coral carbonate production at Jicaral Chachacual, San Agustín and Isla Cacaluta, but 16 and 27% at Isla Montosa and La Entrega. On balance, coral accretion exceeds sea urchin erosion at all sites examined at Huatulco. At Bahias de Huatulco coral reef communities are actively growing, though in the coming years, it might be necessary to investigate the local effects of the interaction among erosion, and environmental and human induced perturbations

Bioerosion caused by the sea urchin Diadema Mexicanum (Echinodermata: Echinoidea) at Bahías de Huatulco, Western Mexico.

Mexican Pacific sea urchin studies have been focused mainly on species distribution, ecology and fisheries. Reef degradation by sea urchin bioerosion has not been studied previously en these reefs. We investigate the importance of Diadema mexicanum as a bioerosive agent of coral carbonate at Bahias de Huatulco, and the relative magnitude of coral accretion and bioerosion. At each of five localities in Bahias de Huatulco, sea urchin density, feeding and mechanical (spine) erosion was determined for three size class intervals. In general, D. mexicanum do not exert any significant role on coral reef community structure (live coral, dead coral or algal coverage) at the Huatulco area, probably because they are generally small (2.9-4 cm test size) and few in number (1.0-6.8 ind.m-2). Mean bioerosion rates are consistent with those measured for other diadematoids, as well as other urchin species in various eastern Pacific localities. However, the degree of bioerosive impact depends on species, test size, and population density of urchins. Coral carbonate removal by D. mexicanum erosion varies from 0.17 to 3.28 kgCaCO3m(-2)yr(-1). This represents a carbonate loss of < 5% of the annual coral carbonate production at Jicaral Chachacual, San Agustín and Isla Cacaluta, but 16 and 27% at Isla Montosa and La Entrega. On balance, coral accretion exceeds sea urchin erosion at all sites examined at Huatulco. At Bahias de Huatulco coral reef communities are actively growing, though in the coming years, it might be necessary to investigate the local effects of the interaction among erosion, and environmental and human induced perturbations.

Determinación de triptófano en cerebro de ratas expuestas a ozono / Brain tryptophan levels in rats exposed to ozone

El objetivo del presente trabajo es cuantificar los niveles de triptófano por CLAR líquidos de alta resolución en 4 regiones del cerebro (cerebelo, corteza, hemisferio y tallo) en ratas machos de la cepa Wistar, de 50 días de edad con diferente condición nutricional expuestas a ozono o aire. Un grupo de animales fue alimentado con una dieta normal de bioterio (23 por ciento de proteína), y otro con una dieta deficiente en proteínas (7 por ciento de proteína). Ambos grupos fueron expuestos a 0.5 ppm de ozono o aire fresco, por 6 horas al día durante 30 días consecutivos. Los resultados muestran diferencias significativas en los niveles de triptófano en todas las regiones del estudio entre los grupos con diferente condición nutricional (p<0.05). Estos resultados sugieren que la alimentación deficiente en proteínas y la exposición a ozono, son condiciones que favorecen la formación de diversas reacciones que alteran los niveles de triptófano en el cerebro

Efecto de la deficiencia de proteínas sobre la peroxidación de lípidos en cerebro de ratas / efect of protein deficiency on lipid peroxidation in brain of rats

El objetivo del presente trabajo es evaluar la formación de radicales libres así como la peroxidación de lípidos en cerebro de ratas machos de la cepa Wistar, de 51 días de edad con diferente condición nutricional, en un diseño factorial 1 x 2, alimentadas ad libitum. Un grupo de ratas fue alimentado con una dieta normal (23 por ciento de proteína), y otro grupo con una dieta normo-calórica hipoprotéica (7 por ciento de proteína), durante 30 días. Semanalmente se midió el nivel de glutatión oxidado en sangre, y al final del experimento se determinó la peroxidación de lípidos en cerebro, mediante la cuantificación de las sustancias reactivas al ácido tiobarbitúrico (TBARS). Los resultados presentaron diferencias estadísticamente significativas, en los niveles de glutatión oxidado en sangre y de TBARS en cerebro, entre los grupos con diferente dieta (p<0.05). Por lo que se sugiere, que existe una relación cualitativa en las alteraciones bioquímicas de los animales del estudio.

[Changes in body weight and the distribution of adipose tissue in hysterectomized postmenopausal patients on estrogen replacement therapy]. / Modificación del peso corporal y distribución del tejido adiposo en pacientes posmenopáusicas histerectomizadas con terapia estrogénica de reemplazo.

The purpose was to look how the weight and body fat distribution is modified after estrogen replacement therapy (ERT). 52 patients older 40 years age, hysterectomized and with bilateral salpingo-oophorectomy were studied. They were divided in two groups: I) received ERT with conjugated equine estrogens 0.625 mg daily (n = 35) and II) with no ERT (n = 27) (control). Every three months corporal weight, body mass index (BMI) and waist-hip ratio was measured for a 12-month period. With the exception of the control group, which was only studied for three months. In the ERT group the corporal weight and the BMI significantly increased at six months (p < 0.01 y p < 0.006, respectively), without changes in the other parameters. The control group had no significant changes in the analyzed parameters during the study time. When the group with ERT was compared with the control group at third month, there was a significant increase in weight (p < 0.05) in the control group. Without any differences in the other analyzed variables between the groups. It was not possible to demonstrate that corporal weight and body fat distribution were permanently modified in those patients with ERT. These data agree with recent reports in which no changes have been detected with hormone replacement therapy usage.

Hypofibrinogenemia-dysfibrinogenemia and von Willebrand's disease in the same family.

Two Puerto Rican families were studied. One family included a number of members with dysfibrinogenemia occasionally associated with hypofibrinogenemia. The second family had members with von Willebrand's disease. The two diseases merged in the proband's immediate family; the affected members of this family exhibited a mild bleeding disorder. Others in the two families had no obvious bleeding tendency.