Radiolysis of nucleosome core DNA: a modelling approach

PURPOSE: To calculate the expected pattern of frank strand breaks (FSB) induced in the DNA of a nucleosome core particle (NCP) by the attack of radiolytic OH* radicals and to compare this with the experimental pattern of FSB induced by the in vitro irradiation of chicken NCP. MATERIALS AND METHODS: The structure of NCP was obtained from the PDB databank. Using molecular modelling, the structure of a linear DNA fragment with the central 60 bp sequence of NCP-DNA was determined. The accessibility of the sugar attack sites to OH* radicals at each nucleotide of the linear fragment or of the NCP-DNA was calculated. The probability of reaction of OH* with each sugar reactive site was calculated using a Monte-Carlo method-based stochastic model. RESULTS: The accessibility of attack sites in the NCP-DNA and the calculated probabilities of sugar attack are mainly modulated through masking by histones, and only slightly through bending. The periodicity of the calculated FSB probabilities is identical to that of the experimental FSB probabilities in chicken NCP (period 10.4 +/- 0.1 bp). CONCLUSIONS: The good agreement between the calculated and experimental results recommends the presented modelling procedure as a tool in predicting the radiosensitivity of DNA in DNA-ligand complexes of known structure.     

Radiation damage to triplex DNA induced by gamma-rays: a footprinting study and Monte Carlo simulation

PURPOSE: This study is aimed at comparing the radiosensitivity of a 21-mer DNA fragment in duplex and triplex form (Py x Pu duplex and Py x Pu:Py triplex) and to give insights into the fine structural features due to the different strandedness. MATERIALS AND METHODS: The triplex sample was characterized by means of electrophoretic mobility, circular dichroism spectra and UV melting experiments. Triplex and duplex, labelled on the homopyrimidine or homopurine strand, were irradiated with 60Co gamma-rays. The samples were analysed by sequencing gel electrophoresis and the patterns of relative probabilities of frank strand breakage (FSB) and alkali-revealed breakage (ARB) at each nucleotide site were determined. Relative probabilities of OH* radical attack to duplex and triplex DNA built up with a molecular modelling software were calculated using a previously reported simulation procedure (Sy et al. 1997). The experimental data were compared with the results of the theoretical simulations of OH* radical attack to DNA. RESULTS: Globally, the duplex is more attacked than the triplex, mainly in the Pu strand. Sequence-dependent variations of FSB and FSB+ARB probabilities in both duplex and triplex were revealed. No significant differences between the patterns of damage in the triplex and in the duplex were observed. CONCLUSIONS: The presence of the third Py strand located in the major groove of the DNA duplex modifies the total yields of radiation-induced DNA damage, but not the sequence-dependent patterns of relative probability of damage at each nucleotide site.     

Can Smart Pens Help Improve Diabetes Management?

Smart pen technology has evolved over the past decade with new features such as Bluetooth connectivity, bolus dose calculators, and integration with mobile apps and continuous glucose monitors. While similar in appearance to a traditional insulin pen, smart pens have the ability to record and store data of insulin injections. These devices have the potential to transform diabetes management for clinicians, and patients with type 1 and type 2 diabetes on insulin therapy by improving adherence, glycemic control, and addressing barriers to diabetes management. Smart pens can also highlight the relationship between insulin, food, and physical activity, and provide insight into optimizing insulin regimens. Education of clinicians and patients, and more clinical studies showing the benefits of smart pens and cost-effectiveness, are needed.     

Luxation latérale complète en hyperpronation du coude

The authors report an exceptional case of hyperpronated complete lateral elbow dislocation with an associated chip fracture of the radial head after a motor vehicle accident. Closed reduction and physical rehabilitation were performed with a good outcome after 2 years. This exceptional case should be included in Speed classification of lateral elbow dislocations as a type IV according to its anatomopathological and clinical features.     

Musculoskeletal symptoms and associated risk factors among African hair braiders

African hair braiders are potentially subject to work-related musculoskeletal disorders (WMSDs) because they perform repetitive hand motions for many hours a day together with prolonged standing and/or prolonged sitting. A complete enumeration of African hair braiders was attempted in Oklahoma City (OKC) and Dallas/Fort Worth (DFW). Braiders were identified through the channels they typically use to offer services to clients. Potential risk factors and symptoms of WMSDs were assessed using an oral interview. Participation rates were 95% (18/19) in OKC and 83% (83/101) in DFW. More than 75% of braiders reported discomfort in the fingers, wrist/hand, upper back, and lower back. In multivariate analysis, years worked as a braider but not age was a significant risk factor (p < 0.005) for reported pain in the wrist/hand, time spent sitting during the work day was found to be a significant predictor (p < 0.05) of upper back pain and lower back pain, and time spent sitting and time spent standing during the work day were both significant predictors (p < 0.05) of shoulder pain. Braiders in OKC, where licensing requirements were stricter, were significantly more likely than braiders in DFW to work at home (67% vs. 4%, p < 0.001) and to report pain in the lower leg (p < 0.005) and ankle/foot (p < 0.05). The close-knit nature of the African hair braiding community makes it an appealing candidate for community-based participatory research aimed at further elucidating occupational health concerns and reducing risk.