Long-term follow-up of radiation accident patients in Peru: review of two cases

Overexposure to radioactive sources used in radiotherapy or industrial radiography may result in severe health consequences. This report assesses the initial clinical status and the medical and psychological long-term follow-up of two radiation accident patients from Peru during the mid-to-late 1990s: one patient exposed to a radiotherapy (60)Co source in Arequipa, the other patient to a (192)Ir source in Yanango. Commonalities and differences are described. The main causes in both accidents were human error and the failure to apply appropriate safety guidelines and standard operating procedures. Education and training of the personnel working with radiation sources are essential to prevent accidents. The experience gained from the medical management of the two patients is valuable for future treatment of such patients.

Left-to-right distribution of periodontal disease

AIM

Symmetry is a property established in many human biological systems and it is reasonable to expect that it may also exist in the mouth. The objective of this study was to examine whether there is a similar left-to-right distribution in periodontal disease.

METHOD

Records of 197 patients from the Periodontics department of The Royal Dental Hospital of Melbourne were analysed. The clinical parameters recorded were pocket probing depth, recession, bleeding on probing, mobility and furcation involvement.

RESULTS

The average age of our sample group was 47.5 years old, with 34.5% men and 65.5% women. The results demonstrated significant left-to-right distribution with all the periodontal indices recorded.

CONCLUSION

The findings support previous studies that show that a similar left-to-right distribution exists in the population studied.

Thermal Properties of Mineralized and Non Mineralized Type I Collagen in Bone

The research about the structural stability of bone, as a composite material, compromises a complete understanding of the interaction between the mineral and organic phases. The thermal stability of human bone and type I collagen extracted from human bone by different methods was studied in order to understand the interactions between the mineral and organic phases when is affected by a degradation/combustion process. The experimental techniques employed were calorimetry and infrared spectroscopy (FTIR) techniques. The extracted type I collagens result to have a bigger thermal stability with a Tmax at 500 and 530 Celsius degrees compared with the collagen present in bone with Tmax at 350 Celsius degrees. The enthalpy value for the complete degradation/combustion process were similar for all the samples, being 8.4 +- 0.11 kJ/g for recent bones diminishing with the antiquity, while for extracted collagens were 8.9 +- 0.07 and 7.9 +-1.01 kJ/g. These findings demonstrate that the stability loss of type I collagen is due to its interactions with the mineral phase, namely carbonate hydroxyapatite. This cause a change in the molecular properties of the collagen during mineralization, specifically in its cross-links and other chemical interactions, which have a global effect over the fibers elasticity, but gaining tensile strength in bone as a whole tissue. We are applying this characterization to analyze the diagenetic process of bones with archaeological interest in order to identify how the environmental factors affect the molecular structure of type I collagen. In bone samples that proceed from an specific region with the same environmental conditions, the enthalpy value per unit mass was found to diminish exponentially with respect to the bone antiquity.

Microstructure and Thermal Expansion Properties of Ostrich Eggshell

Textures of calcite crystals from ostrich (Struthio camelus) eggshells were examined with X ray diffractometry (XRD), transmission and scanning electron microscopy (TEM, SEM), and the thermal stability by thermal expansion analysis (TEA). Results showed that textures vary through the thickness of the eggshell and that expansion properties and thermal behaviour are unusual. Crystals from ostrich eggshell are arranged in two main configurations or layers; the outer layer with the c-axis of crystals oriented perpendicular to the eggshell surface and the inner layer with the c-axes of the crystals arranged almost parallel to eggshell surface; thermal expansion analysis show high stability through a wide range of temperatures until a steep growth near 450-460°C. These results show that the manipulation of crystal texture and properties is under biological control and a better understanding of this biological phenomenon will provide more and better data for improving new synthetic composite materials.

Chemical reactions in 2D: self-assembly and self-esterification of 9(10),16-dihydroxypalmitic acid on mica surface

9(10),16-Dihydroxypalmitic acid (diHPA) is a particularly interesting polyhydroxylated fatty acid (1) because it is the main monomer of cutin, the most abundant biopolyester in nature, and (2) because the presence of a terminal and a secondary hydroxyl group in midchain positions provides an excellent model to study their intermolecular interactions in a confined phase such as self-assembled layers. In this study we have combined atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectroscopy, as well as molecular dynamics (MD) simulations to conclude that the self-assembling of diHPA molecules on mica is a layer by layer process following a Brunauer-Emmett-Teller (BET) type isotherm and with the first layer growing much faster than the rest. Interactions between secondary hydroxyls reinforce the cohesive energy of the monolayer, while the presence of the terminal hydroxyl group is necessary to trigger the multilayered growth. Besides, XPS and ATR-FT-IR spectroscopies clearly indicate that spontaneous self-esterification occurs upon self-assembling. The esterification reaction is a prerequisite to propose a self-assembly route for the biosynthesis of cutin in nature. Molecular dynamics simulations have shown that internal molecular reorganization within the self-assembled layers provides the appropriate intermolecular orientation to facilitate the nucleophilic attack and the release of a water molecule required by the esterification reaction.

Cardiopulmonary adaptation in large for gestational age infants of diabetic and nondiabetic mothers

AIM

To compare cardiopulmonary adaptation in large for gestational age infants of diabetic and nondiabetic mothers.

METHODS

Color Doppler echocardiography was performed in 113 (22 large for gestational age infants of diabetic mothers, 21 of nondiabetic mothers and 70 adequate for gestational age newborns) full-term infants.

RESULTS

Pulmonary arterial pressure was significantly higher in infants of diabetic mothers than in those of nondiabetic mothers and normal infants at 24 h (38.5 vs. 32.5, and 35.5 mmHg, respectively). However, slow fall in this parameter was shown in all large for gestational age infants. Open ductus arteriosus was frequent in all large for gestational age infants, but its closure was significantly delayed in infants of diabetic mothers. Septal hypertrophy was higher in infants of diabetic mothers than in large for gestational age infants of nondiabetic mothers.

CONCLUSION

Large for gestational age infants born from nondiabetic mothers showed delayed fall in pulmonary arterial pressure similar to those born from diabetic mothers but showed lower proportion of septal hypertrophy. Patent ductus arteriosus persisted for longer period of time in all large for gestational age infants than in normal infants, but its closure was significantly delayed in infants of diabetic mothers.