Development and validation of regression-based QSAR models for quantification of contributions of molecular fragments to skin sensitization potency of diverse organic chemicals

In our present work, we have developed regression-based QSAR models for skin sensitization potential of 51 diverse organic chemicals. The objective behind the present work is to determine the influence of different molecular features on the skin sensitizing potential of chemicals. Among several models developed, the two best ones are discussed to unveil specific information regarding the contribution of different structural and physicochemical features towards the property of skin sensitization. The QSAR models suggested that aromatic compounds are more skin sensitizing than aliphatic ones, but in the case of carbonyl compounds, aliphatic ones are more skin sensitizing than aromatic ones. Other descriptors such as LUMO and <2-Atype_H-47> signify the importance of the electrophilic and hydrophilic character respectively of the molecules for showing skin sensitizing property. Another two descriptors, <Dipole-mag-2.72> and (3)χC also exert significant contributions towards the skin sensitization potential of the chemicals. Further, it is observed that the nitrogen atoms (nN), triple bonds (nTB) and also the fragment Al-C(=X)-Al (Atype_C38) are responsible for skin sensitizing property. All the above information provides additional support for further research involving identification of the skin sensitization potential of new chemicals.

Police officer anxiety after occupational blood and body fluid exposure

BACKGROUND

In the course of their work, police staff are at risk of exposure to blood and body fluids (BBF) and potentially at risk of acquiring a blood-borne viral infection.

AIMS

To examine levels of anxiety among Scottish police staff following an occupational exposure to BBF.

METHODS

Police staff who reported an incident of exposure to their occupational health (OH) provider were invited to complete a postal questionnaire about their levels of self-reported anxiety after the incident and after contact with medical services (namely, OH and accident and emergency (A&E)).

RESULTS

Seventy exposed individuals (66% of those invited to take part) completed a questionnaire. Participants' self-reported anxiety after the incident varied widely. Levels of anxiety reduced over time and following contact with medical services. A&E staff were more likely to be the first point of medical contact for the most anxious individuals. Pre-incident training was not associated with post-incident anxiety.

CONCLUSIONS

The findings suggest that contact with medical services helps to alleviate post-exposure anxieties among police staff.

Occupational transmission of hepatitis C in healthcare workers and factors associated with seroconversion: UK surveillance data

The study aims were to describe a case series of occupationally acquired hepatitis C (HCV) infections in UK healthcare workers and examine factors associated with transmission using exposure data reported to the Health Protection Agency between July 1997 and December 2007. Fifteen reported cases of documented HCV seroconversion occurred after percutaneous exposure, the majority from hollow-bore needles used in the source patient's vein or artery and contaminated with blood or blood-stained fluid. The seroconversion rate was 2.2% (14/626). In multivariable analysis of healthcare workers with percutaneous exposure to blood or blood-stained fluid, we demonstrate that blood sampling procedures (odds ratio [OR], 5.75; 95% CI, 1.33-24.91; P = 0.01) and depth of injury (OR for deep vs superficial injury, 21.99; 95% CI, 2.02-239.61; P = 0.02) are independently associated with a greater risk of HCV seroconversion. This is the first UK study of occupationally acquired HCV in healthcare workers. It has reinforced our knowledge of risk factors for HCV transmission. Most of these exposures and transmissions were preventable. Healthcare employers should provide regular education on the risks of occupational exposure and prevention through standard infection control procedures. They should ensure the availability of effective prevention measures and facilitate prompt reporting and adequate follow-up of exposures.

QSTR with extended topochemical atom (ETA) indices. 15. Development of predictive models for toxicity of organic chemicals against fathead minnow using second-generation ETA indices

Modern industrialisation has led to the production of millions of toxic chemicals having hazardous effects on the ecosystem. It is impracticable to determine the toxic potential of a large number of chemicals in animal models, making the use of quantitative structure-toxicity relationship (QSTR) models an alternative strategy for toxicity prediction. Recently we introduced a set of second-generation extended topochemical atom (ETA) indices for predictive modelling. Here we have developed predictive toxicity models on a large dataset of 459 diverse chemicals against fathead minnow (Pimephales promelas) using the second-generation ETA indices. These descriptors can be easily calculated from two-dimensional molecular representation without the need of time-consuming conformational analysis and alignment, making the developed models easily reproducible. Considering the importance of hydrophobicity for toxicity prediction, AlogP98 was used as an additional predictor in all the models, which were validated rigorously using multiple strategies. The ETA models were comparable in predictability to those involving various non-ETA topological parameters and those previously reported using various descriptors including computationally demanding quantum-chemical ones.

Chimeric aptamers in cancer cell-targeted drug delivery

Aptamers are single-stranded structured oligonucleotides (DNA or RNA) that can bind to a wide range of targets ("apatopes") with high affinity and specificity. These nucleic acid ligands, generated from pools of random-sequence by an in vitro selection process referred to as systematic evolution of ligands by exponential enrichment (SELEX), have now been identified as excellent tools for chemical biology, therapeutic delivery, diagnosis, research, and monitoring therapy in real-time imaging. Today, aptamers represent an interesting class of modern Pharmaceuticals which with their low immunogenic potential mimic extend many of the properties of monoclonal antibodies in diagnostics, research, and therapeutics. More recently, chimeric aptamer approach employing many different possible types of chimerization strategies has generated more stable and efficient chimeric aptamers with aptamer-aptamer, aptamer-nonaptamer biomacromolecules (siRNAs, proteins) and aptamer-nanoparticle chimeras. These chimeric aptamers when conjugated with various biomacromolecules like locked nucleic acid (LNA) to potentiate their stability, biodistribution, and targeting efficiency, have facilitated the accurate targeting in preclinical trials. We developed LNA-aptamer (anti-nucleolin and EpCAM) complexes which were loaded in iron-saturated bovine lactofeerin (Fe-blf)-coated dopamine modified surface of superparamagnetic iron oxide (Fe₃O₄) nanoparticles (SPIONs). This complex was used to deliver the specific aptamers in tumor cells in a co-culture model of normal and cancer cells. This review focuses on the chimeric aptamers, currently in development that are likely to find future practical applications in concert with other therapeutic molecules and modalities.

On some novel extended topochemical atom (ETA) parameters for effective encoding of chemical information and modelling of fundamental physicochemical properties

Extended topochemical atom (ETA) indices developed by our group have been extensively applied in our previous reports for toxicity and ecotoxicity modelling in the field of quantitative structure-activity relationships (QSARs). In the present study these indices have been further explored by defining additional novel parameters to model n-octanol-water partition coefficient (two data sets; n = 168 and 139), water solubility (n = 193), molar refractivity (n = 166), and aromatic substituent constants π, MR, σ (m), and σ (p) (n = 99). All the models developed in the present study have undergone rigorous internal and external validation tests and the models have high statistical significance and prediction potential. In terms of Q² and r² values the models developed for the datasets of whole molecules are better than those previously reported, with topochemically arrived unique (TAU) indices on the same datasets of chemicals. An attempt has also been made to develop models using non-ETA topological and information indices. Interestingly, ETA and non-ETA models have been found to have similar predictive capacity.

Applications of aptamers in nanodelivery systems in cancer, eye and inflammatory diseases

Aptamers are an interesting class of molecules that have potential in many facets of human health. They are characterized by high affinity and specificity to their targets, are small in size, have similar properties to antibodies, but are made synthetically. All of these properties, among others, give aptamers the potential to diagnose, image and treat like no other molecules. By combining the unique properties of aptamers with the ever expanding field of nanotechnology and all it has to offer, we are entering a very promising new area of targeted nanodelivery treatments. These treatments have found success in the complex disease processes of cancer, eye and inflammatory diseases.

Perianesthetic management of the first robotic partial cystectomy in bladder pheochromocytoma. A case report

The authors report the perianesthetic considerations of a rare case of pheochromocytoma of the urinary bladder for which the first reported robotic partial cystectomy and ureteric reimplantation were performed. A 59-year-old male patient, known to be hypertensive, was posted for transurethral resection of a bladder tumor. In the operation room, after attaching the monitors, a subarachnoid block was given. Upon manipulation of the tumor, the blood pressure and heart rate increased markedly. A pheochromocytoma was suspected and was later confirmed by raised urine catecholamine levels and meta-iodobenzyl-guanidine scan. The patient was started on tablet prazosin and atenolol. After optimization, a robotic partial cystectomy was planned. In the operating room, an epidural catheter and a radial artery cannula were inserted. After the induction of anesthesia and the securing of the airway, surgery was started. After the insertion of the verres needle, pneumoperitoneum was created very slowly, and then the patient was positioned in 40 degrees Trendelenburg. Surges in arterial blood pressure (ABP) were managed with titrated doses of sodium nitroprusside and nitroglycerine and boluses of esmolol and labetalol. ABP drops postoperatively were managed with fluid and dopamine infusion. Robotic surgery is a safe alternative to the open technique for pheochromocytoma of the urinary bladder. Care should be taken during the positioning of the patient for robot placement and during pneumoperitoneum creation.

QSAR with quantum topological molecular similarity indices: toxicity of aromatic aldehydes to Tetrahymena pyriformis

Extensive production and utilization of aromatic aldehydes and their derivatives without proper certification is alarming with regard to environmental safety. This concern motivated our construction of predictive quantitative structure-activity relationship (QSAR) models for the toxicity of aldehydes to the ecologically important species Tetrahymena pyriformis. Quantum topological molecular similarity (QTMS) descriptors, along with the lipid-water partition coefficient (log K(o/w)), were used as predictor variables. The QTMS descriptors were calculated at different levels of theory including AM1, HF/3-21G(d), HF/6-31G(d), B3LYP/6-31 + G(d,p), B3LYP/6-311 + G(2d,p) and MP2/6-311+G(2d,p). The data set of 77 aromatic aldehydes was divided into a training set (n = 58) and a test (n = 19) set, and 58 models were developed using partial least squares (PLS) and genetic partial least squares (G/PLS). We evaluated the overall predictive capacity of the models based on leave-one-out predictions for the training set compounds and model derived predictions for the test set compounds. For both PLS and G/PLS, the models built at the HF/6-31G(d) level show better predictivity (based on overall prediction) than the models developed at any of the other five levels. Further validation was also performed utilizing (process and model) randomization tests. We show that improved predictive QSAR models for aldehydic toxicity to Tetrahymena pyriformis can be generated using QTMS descriptors along with log K(o/w).

Exhaled breath condensate biomarkers in COPD

Biomarkers in chronic obstructive pulmonary disease may be useful in aiding diagnosis, defining specific phenotypes of disease, monitoring exacerbations and evaluating the effects of drugs. Exhaled breath condensate is a noninvasive means of sampling the airways, allowing biomarkers of airway inflammation and oxidative stress to be measured. In the present review, the use of exhaled breath condensate biomarkers in chronic obstructive pulmonary disease is explored and potential applications in diagnosis, disease phenotyping, exacerbation monitoring and clinical trials are considered. Exhaled breath condensate biomarkers are comprehensively reviewed in terms of method validation, reproducibility, disease specificity and sensitivity to detect changes in airway inflammation. The commonly used exhaled breath condensate methodologies in chronic obstructive pulmonary disease patients are shown to have considerable variability, due to technical issues concerning both sample collection and analysis. Despite these issues, there is still data to support the use of exhaled breath condensate biomarkers for monitoring chronic obstructive pulmonary disease exacerbations and the response to pharmacological intervention. Further improvements to sample collection and analysis methods will improve the sensitivity of these biomarkers. The use of cytokine arrays, mass spectrometry and nuclear magnetic resonance profiling of exhaled breath condensate has opened a new avenue for analysis, as hypothesis generation from such profiling may lead to further selection of biomarkers for specific analysis.