Quantitative Analysis of Tooth Mineral Content by High Resolution Micro-computed Tomography

Teeth and bones are highly mineralized tissues containing inorganic minerals such as calcium phosphate, and a growing number of evidences show that their mineral content is associated with many diseases. Although the quantification of mineral contents by micro-computed tomography(micro- CT) has been used in diagnosis and evaluation for treating bone diseases, its application for teeth diseases has not been well established. In this study, we attempted to estimate a usefulness of a high-resolution micro-CT in analysis of human teeth. The teeth were scanned by using the Skyscan 1172 micro-CT. In order to measure tooth mineral content, beam hardening effect of the machine was corrected with a radiopaque iodinecontaining substance, iodoacetamide. Under the maximum resolution of 6.6 µm, X-ray densities in teeth and hydroxyapatite standards were obtained with Hounsfield unit (HU), and they were then converted to an absolute mineral concentration by a CT Analyzer software. In enamel layer of cusp area, the mean mineral concentration was about 2.14 mg/mm³ and there was a constant mineral concentration gradient from the enamel surface to the dentinoenamel junction. In the dentin of middle 1/3 of tooth, the mean mineral concentration was approximately 1.27 mg/mm³ and there was a constant mineral concentration gradient from the outer of root to the pulp side, ranging from 1.3 to 1.06 mg/mm³. In decay region of dentin, the mineral content was gradually decreased from the intact inner side to the decayed surface. These results suggest that high-resolution micro-CT can be as a useful tool for non-invasive measurement of mineral concentration in teeth.

La Escuela de Salud Pública de México: innovación educativa y tecnológica en el nuevo milenio / School of Public Health of Mexico: Educational and technological innovation in the new millennium

Este artículo fue concebido para analizar la función de la Escuela de Salud Pública de México (ESPM) desde el año 2000 hasta el presente. Uno de sus puntos centrales es el análisis del proceso de reorientación de la labor educativa de la escuela con la finalidad de responder a los retos en materia de salud y educación surgidos a finales del siglo XX. Para exponer cómo ha evolucionado dicho proceso, retomamos tres ejes rectores que caracterizan la labor de la escuela en la actualidad: el cambio de modelo pedagógico, la incorporación de las tecnologías de la información y las comunicaciones, y la profesionalización de la docencia. Con la exposición de este tema, y a través del contraste entre el pasado y el presente, buscamos completar la historia de trabajo ininterrumpido de la Escuela durante sus 92 años de existencia, que ha trascendido los confines del país.

This article was conceived to analyze the work of the School of Public Health of Mexico (ESPM for is acronym in Spanish) from the year 2000 to the present day. One of the highlights that we will examine is the reorientation of the educational work of the school in order to meet the challenges in health and education that emerged during the end of the twentieth century. In order to explain the evolution of this process, we will describe the three main guiding principles that characterize the present work of the school: the pedagogical model's change, the incorporation of the information and communication technologies, and the professionalization in teaching. The purpose of this work is to define those guiding principles, and to expose, through the contrast between past and present, the complete history of uninterrupted work of the School of Public Health of Mexico during its ninety-two years of existence, that has gone beyond the boundaries of the country.

Effect of ECQ on Iodoacetamide-Induced Chronic Gastritis in Rats

This study investigated effect of extract containing quercetin-3-O-beta-D-glucuronopyranoside from Rumex Aquaticus Herba (ECQ) against chronic gastritis in rats. To produce chronic gastritis, the animals received a daily intra-gastric administration of 0.1 ml of 0.15% iodoacetamide (IA) solution for 7 days. Daily exposure of the gastric mucosa to IA induced both gastric lesions and significant reductions of body weight and food and water intake. These reductions recovered with treatment with ECQ for 7 days. ECQ significantly inhibited the elevation of the malondialdehyde levels and myeloperoxidase activity, which were used as indices of lipid peroxidation and neutrophil infiltration. ECQ recovered the level of glutathione, activity of superoxide dismutase (SOD), and expression of SOD-2. The increased levels of total NO concentration and iNOS expression in the IA-induced chronic gastritis were significantly reduced by treatment with ECQ. These results suggest that the ECQ has a therapeutic effect on chronic gastritis in rats by inhibitory actions on neutrophil infiltration, lipid peroxidation and various steps of reactive oxygen species (ROS) generation.

Iodoacetamide-induced aquaporin 1 expression in fibroblasts is energy-dependent / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the impact of energy metabolism at the cellular level on the expression of the water channel protein aquaporin 1 (AQP1).</p><p><b>METHODS</b>Balb/c mouse fibroblasts were incubated with iodoacetamide (IA) in vitro, and the changes in AQP1 expression were detected by immunoblotting and immunohistochemistry at 0, 4, and 6 h.</p><p><b>RESULTS</b>IA induced the expression of AQP1 at 4 and 6 h accompanied with cell death. Reverse transcription PCR showed an increased expression of AQP1 mRNA in the cells. AQP1 expression was also upregulated by the inhibitor of microtubule and cytochrome C oxidase.</p><p><b>CONCLUSION</b>A pretranslational regulation occurs in IA-induced AQP1 expression in mouse fibroblasts, and the up-regulated AQP1 accumulation is characterized by mitochondria-related energy dependence.</p>

Mechanism of intragastric amoxicillin protection against 96 percent ethanol damage in rat stomach

The purpose of this study was to investigate the role played by endogenous prostaglandins, sulfhydryls, gastric motility, fluid volume, and mucus volume retained in the gastric lumen in the protection offered by intragastric amoxicillin against ethanol-induced gastric lesions. It has been demonstrated that intragastric administration of amoxicillin (Amx) dose-dependently protected the rat gastric mucosa from 96 per cent ethanol-induced lesions. The inhibition of the lesions was 28, 41.4, 84.7 and 90 per cent at doses of 50, 100, 200 and 400 mg/Kg, respectively. The gastroprotective effect of Amx was significantly reversed by pretreatment with both indomethacin (5 mg/Kg, subcutaneously), a cyclooxygenase inhibitors, and iodoacetamide (100 mg/Kgm subcutaneously), a sulfhydryl blocker. Gastric motility was measured by a ballon method. There was not any significant differences between Amx (50-400 mg/Kg)-induced and spontaneous motility with regard to both amplitudes and frequently of gastric contraction. One milliliter of 96 per cent ethanol produced hemorrhagic bandlike lesions in the corpus mucosa with the occurrence of a complete inhibition of the amplitude and frequency of gastric contraction. This inhibition of gastric motility caused by ethanol was not modified by pretreatment of Amx (400 mg/Kg) alone, indomethacin plus Amx or iodoacetamide plus Amx. In addition, there was a significant increase in the mucus volume retained in the gastric lumen for Amx (200 and 400 mg/Kg) at 30 min after its adminitration. We conclude that the intragastric Amx prospective effect aginst 96 per cent athanol-induced mucosal lesions may be mediated by endogenous prostaglandins, sulfhydryl compounds of the gastric mucosa, an increase in mucus volume retained in the gastric lumen at the time when ethanol is administered, and is not associated with the gastric motor activity.

Changes in protein profile during coagulation of latex from Carica papaya

We describe the changes in peptide composition by SDS-PAGE analysis of latex from Carioca papaya collected at various times after incision of the unripe fruit. The data show that during latex coagulation several peptides are processed in an orderly fashion.

Thioctic acid protection against ethanol-induced gastric mucosal lesions involves sulfhydryl and prostagladin participation

Thioctic acid, a sulfhydryl agent, given orally macroscopically protected the gastric mucosa from 96 percent ethanol-induced lesions in a dose-and time dependent fashion. The inhibition of the lesions was 56.0 and 90.3 percent at doses of 25 and 50 mg/Kg, respectively. The duration of its protective effect was appoximately 120 minutes. Histopathologically, the oral administration of thioctic acid prevented necrotic mucosal lesions in the deeper part of the mucosa but did not protect the surface epithelial cells against ethanol challenge. Gastric motility measured by a ballon method, was dose-dependently inhibited by the oral administration of thioctic acid. Thioctic acid protection was suppressed by pretreatment with indomethacin (30 mg/Kg), a cyclooxygenase inhibitor, and iodoacetamide (100 mg/Kg), a sulfhydryl bloker. The gastric motility inhibited by oral thioctic acid was not reversed by indomethacin or iodoacetamide. These doses of indomethacin or iodomethamide were administered because previously they had been used to suppress endogenous prostagladins, and nonprotein sulfhydryls of the gastric mucosa, respectively. There was an increase in the fluid volume retained in the gastric lumen for thioctic acid (50 mg/Kg) at 30,60,90, and 120 minutes after administration. There was an increase in the mucus volume retained in the gastric lumen for thioctic acid (50, 25 mg/Kg) at 120 minutes after administration. The lesion area in the rats treated with 70 mul of vehicle and in the rats treated with 250 mul of vehicle were significantly higher than in the rats treated with 450 mul of vehicle. The present study suggests that thioctic acid administered orally, affered protection to the rat gastric mucosa against 96 percent ethanol-induced lesions. This protective effect appears to be dependent on prostagladin-and sulfhydryl-sensitive mechanisms, together with an increase in both the fluid volume and the mucus volume retained in the gastric lumen, and is not associated with the inhibition of gastric motor activity.

Rat epididymal sperm exhibit on dithiothreitol treatment in vitro quantifiable differences in patterns of light scatter, uptake of 14C-iodoacetamide and binding of ethidium bromide to DNA.

The extent to which chromatin of rat caput (CAP), corpus (COR), cauda (CAU) spermatozoa undergo condensation and compaction is known to be a function of progressive increase in the formation of inter- as well as intra-protamine disulphide bridges during their transit through the epididymis. Relative compaction undergone by the nuclear chromatin of these sperm populations was studied by monitoring their susceptibility to in vitro decondensation induced by varying concentrations (0, 0.01, 1, 5, 10, 50 mM) of disulphide reducing agent, dithiothreitol (DTT) after an initial exposure to 0.01% papain. Following this treatment and staining with the nucleic acid specific fluorochrome, ethidium bromide (EB), it was observed that irrespective of the epididymal region from which they were collected, spermatozoa exhibited DTT dose-dependent (a) increase in nuclear size as seen under fluorescence microscopic examination, (b) decrease in flow cytometrically quantifiable light scatter parameters--forward scatter (FSc, 'nuclear size') and side scatter (SSc, nuclear 'granularity'), (c) increase in individual cell EB binding when analyzed by DNA flow cytometry, and (d) increase in thiol specific 14C-iodoacetamide (14C-IA) uptake. The decrease in both FSc and SSc occurring in spite of actual increase in nuclear size has been attributed to increase in translucency of spermatozoan nuclei consequent to decondensation. The FSc, SSc and EB bindability were studied by monitoring both the channels of maximal cell concentration detected in the flow cytograms as well as by digitally quantitating the numbers of cells within specific channels (1-64, 65-128, 129-192 and 193-256) of the flow cytogram. The latter indicated a measure of the variability in the response of populations of sperm within each sample to DTT induced decondensation. At any given concentration of DTT, especially between 5-10 mM, the differences observed between sperms of different regions were consistent and significant (P < 0.01-P < 0.001), maximal changes being shown by CAP and minimal by CAU sperm, COR sperm appearing in between. The effective concentration of DTT required to elicit 50% of maximal (i.e. that exhibited by CAP sperm when taken as 100%) effect (ED50) varied significantly among CAP, COR and CAU sperms for each of the parameters studied (P < 0.01-P < 0.001). It is concluded that the differences observed among the three epididymal sperm populations are due to differences in the extent of susceptibility to decondensation in vitro and that this is dependent upon the variation in the -S-S-content of their chromatin during different stages of epididymal transit. All the parameters used (with the exception of fluorescence microscopy) can be quantified and as all of them show a similar dose dependency to DTT treatment, any one of these parameters can be conveniently used to determine the mature/immature status of the sperms voided. Application of such a method to determine the quality of sperms voided by man appears feasible.

Inactivation of a beta-glucosidase from Arthrobotrys conoides by diethyl pyrocarbonate: evidence of histidine at the active site.

Modification of A. conoides beta-glucosidase by diethylpyrocarbonate caused rapid inactivation of the enzyme. The kinetic analyses showed that the inactivation by diethylpyrocarbonate resulted from the modification of an average of one histidine residue per mole of enzyme. The modified enzyme showed an increase in absorbance at 240 nm. Sulphydryl, lysine and tyrosine residues were not modified by diethylpyrocarbonate treatment. The substrate offered significant protection against diethylpyrocarbonates modification. The results indicate that diethylpyrocarbonate was interacting with the enzyme at or near the active site.