A theoretical study on interactions between mitoxantrone as an anticancer drug and DNA: application in drug design

This research is an effort to further understand the physicochemical interaction between the novel drug, mitoxantrone (MTX) and its biologic receptor, DNA. The ultimate goal is to design drugs that interact more with DNA. Understanding the physicochemical properties of the drug as well as the mechanism by which it interacts with DNA, it should ultimately allow the rational design of novel anti-cancer or anti-viral drugs. Molecular modelling on the complex formed between MTX and DNA presented that this complex was indeed fully capable of participating in the formation of a stable intercalation site. Furthermore, the molecular geometries of MTX and the DNA bases (adenine, guanine, cytosine and thymine) were optimized with the aid of the B3LYP/6-31G* method. The properties of the isolated intercalator and its stacking interactions with the adenine...thymine (AT) and guanine...cytosine (GC) nucleic acid base pairs were studied with the DFTB method (density functional tight-binding), an approximate version of the DFT method, that was extended to cover the London dispersion energy. The B3LYP/6-31G* stabilization energies of the intercalator...base pair complexes were found 10.06 kcal/mol and 21.64 kcal/mol for AT...MTX and GC...MTX, respectively. It was concluded that the dispersion energy and the electrostatic interaction contributed to the stability of the intercalator.DNA base pair complexes. The results concluded from the comparison of the DFTB method and the Hartree-fock method point out that these methods show close results and support each other.     

Multidimensional approach to restraint minimization: The journey of a specialized mental health organization

The executive‐level witnessing and review of restraint events has been identified as a key strategy for restraint minimization. In the present study, we examined the changes in restraint practices at a tertiary‐level mental health‐care facility with implementation of an initiative, in which representatives from senior management, professional practice, peer support, and clinical ethics witnessed seclusion and restraint events, and rounded with clinical teams to discuss timely release and brainstorm prevention strategies. Interrupted time series analysis compared the change from pre‐implementation (14 months prior) to postimplementation (35 months’ following) in the number of incidents/month, total hours/month, and average hours/incident/month for each of seclusion and mechanical restraint. With implementation, there was a step decrease in average hours/seclusion (–28.3 hours/seclusion, P < 0.001) and total seclusion hours (–1264.5 hours, P = 0.002). The postimplementation rate of decrease of –0.9 hours/incident/month was different than the pre‐implementation rate of increase of 0.7 hours/incident/month for mechanical restraint (P = 0.03). Pre‐implementation, there was a rate of decrease of 6.1 incidents/month (P < 0.001) and 4.5 incidents/month (P = 0.001) for seclusion and mechanical restraint, respectively. Postimplementation, there was a rate of increase of 0.3 incidents/month and a rate of decrease of 0.05 incidents/month for seclusion and mechanical restraint, respectively, both of which were different than pre‐implementation (seclusion: P < 0.001, mechanical restraint: P = 0.002). In conclusion, the total hours of seclusion and average hours per seclusion and per restraint incident were reduced, demonstrating the value of leadership witnessing and daily rounds in promoting restraint minimization in tertiary‐level mental health care.     

Exome sequencing revealed a novel deletion in the ERCC8 gene in an Iranian family with Cockayne syndrome

Cockayne syndrome (CS) is one the rare DNA‐repair deficiency disorders with autosomal recessive inheritance. Failure to thrive and microcephaly are the major criteria of diagnosis. Owing to genetic heterogeneity of CS, whole exome sequencing is promising way to determine the genetic basis of the disease. Here, we present c.1053delT in ERCC8 gene in an Iranian family with symptom of CS using whole exome sequencing. The deletion was novel and was not previously reported elsewhere.     

MRI-guided attenuation correction in whole-body PET/MR: assessment of the effect of bone attenuation

Objective

Hybrid PET/MRI presents many advantages in comparison with its counterpart PET/CT in terms of improved soft-tissue contrast, decrease in radiation exposure, and truly simultaneous and multi-parametric imaging capabilities. However, the lack of well-established methodology for MR-based attenuation correction is hampering further development and wider acceptance of this technology. We assess the impact of ignoring bone attenuation and using different tissue classes for generation of the attenuation map on the accuracy of attenuation correction of PET data.

Methods

This work was performed using simulation studies based on the XCAT phantom and clinical input data. For the latter, PET and CT images of patients were used as input for the analytic simulation model using realistic activity distributions where CT-based attenuation correction was utilized as reference for comparison. For both phantom and clinical studies, the reference attenuation map was classified into various numbers of tissue classes to produce three (air, soft tissue and lung), four (air, lungs, soft tissue and cortical bones) and five (air, lungs, soft tissue, cortical bones and spongeous bones) class attenuation maps.

Results

The phantom studies demonstrated that ignoring bone increases the relative error by up to 6.8 % in the body and up to 31.0 % for bony regions. Likewise, the simulated clinical studies showed that the mean relative error reached 15 % for lesions located in the body and 30.7 % for lesions located in bones, when neglecting bones. These results demonstrate an underestimation of about 30 % of tracer uptake when neglecting bone, which in turn imposes substantial loss of quantitative accuracy for PET images produced by hybrid PET/MRI systems.

Conclusion

Considering bones in the attenuation map will considerably improve the accuracy of MR-guided attenuation correction in hybrid PET/MR to enable quantitative PET imaging on hybrid PET/MR technologies.     

Juvenile colloid milium

INTRODUCTION: Colloid Milium is a rare disease. It is characterized by the development, on sun-exposed areas, of clusters of yellow and translucid, hard papules, that seeps a gelatinous substance when opened. This dermatitis predominantly affects elderly patients and, exceptionally, children. We report a case of juvenile colloid milium. OBSERVATION: A 14 year-old boy consulted for papular, translucid or amber-brown lesions, occasionally hemorrhagic on the cheeks, nose upper lip and the upper edge of the helix of both ears. He was born to consanguineous parents. Living in a rural area, he was exposed to sun during agricultural activities. The lesions had progressed since he was 6 years old and were exacerbated in the summertime. There was no similar case in the family. Histological exploration of a papular lesion showed areas of atrophic epidermis and the presence of a few vacuolized keratinocytes. The epidermis was lifted by nodular lumps of amorphous eosinophilic material deposited in the superficial dermis. Staining with Congo red was negative. DISCUSSION: Juvenile colloid milium is a benign but unesthetic dermatitis. The inducing role of sun exposure is obvious, as in colloid milium of adults, but other pathogenic hypotheses also exist.     

Role of lipid peroxidation and PPAR-δ in amplifying glucose-stimulated insulin secretion

OBJECTIVE

Previous studies show that polyunsaturated fatty acids (PUFAs) increase the insulin secretory capacity of pancreatic β-cells. We aimed at identifying PUFA-derived mediators and their cellular targets that are involved in the amplification of insulin release from β-cells preexposed to high glucose levels.

RESEARCH DESIGN AND METHODS

The content of fatty acids in phospholipids of INS-1E β-cells was determined by lipidomics analysis. High-performance liquid chromatography was used to identify peroxidation products in β-cell cultures. Static and dynamic glucose-stimulated insulin secretion (GSIS) assays were performed on isolated rat islets and/or INS-1E cells. The function of peroxisome proliferator–activated receptor-δ (PPAR-δ) in regulating insulin secretion was investigated using pharmacological agents and gene expression manipulations.

RESULTS

High glucose activated cPLA₂ and, subsequently, the hydrolysis of arachidonic and linoleic acid (AA and LA, respectively) from phospholipids in INS-1E cells. Glucose also increased the level of reactive oxygen species, which promoted the peroxidation of these PUFAs to generate 4-hydroxy-2E-nonenal (4-HNE). The latter mimicked the GSIS-amplifying effect of high glucose preexposure and of the PPAR-δ agonist {"type":"entrez-nucleotide","attrs":{"text":"GW501516","term_id":"289075981","term_text":"GW501516"}}GW501516 in INS-1E cells and isolated rat islets. These effects were blocked with GSK0660, a selective PPAR-δ antagonist, and the antioxidant N-acetylcysteine or by silencing PPAR-δ expression. High glucose, 4-HNE, and {"type":"entrez-nucleotide","attrs":{"text":"GW501516","term_id":"289075981","term_text":"GW501516"}}GW501516 also induced luciferase expression in a PPAR-δ–mediated transactivation assay. Cytotoxic effects of 4-HNE were observed only above the physiologically effective concentration range.

CONCLUSIONS

Elevated glucose levels augment the release of AA and LA from phospholipids and their peroxidation to 4-HNE in β-cells. This molecule is an endogenous ligand for PPAR-δ, which amplifies insulin secretion in β-cells.The effect of glucose on β-cell function depends on its concentration and duration of exposure (1). An acute exposure to high glucose triggers the classical biphasic insulin secretion as a result of membrane depolarization and enhanced exocytosis of insulin granules. Chronic hyperglycemia, however, induces β-cell dysfunction as a result of excessive generation of glucose-derived reactive oxygen species (ROS) and accumulation of glycated proteins, which induce endoplasmic reticulum stress and apoptosis. In addition, intermittent or intermediate periods of hyperglycemia influence β-cells differently; a prior exposure of human subjects and animals to high glucose activates “priming” or “memory” pathways that amplify insulin release in comparison with naïve cells (2–4). The amplification of insulin release was described in the compensatory and adaptive phases of type 2 diabetes (1,5).The hypothesis that lipid mediators are involved in this adaptive stage as a result of their amplifying effects on insulin secretion has gained experimental support (6,7). Specifically, the nonesterified polyunsaturated fatty acids (PUFAs), arachidonic acid (AA) and linoleic acid (LA), per se and/or their cyclooxygenase- and lipoxygenase (LO)-derived metabolites were suggested to be such mediators (6,8–10). The idea that phospholipases regulate insulin secretion was introduced by Metz (11) and Dunlop and Larkins (12). Others have reported that high glucose increased the expression of and activated some PLA₂ isotypes, which release fatty acids from the sn-2 position in phospholipids (13).Of interest is the finding that ROS, generated in β-cells under high glucose conditions, also function as insulinotropic signals (14). Among their multiple cellular functions, ROS catalyze the peroxidation of PUFAs and their LO-derived hydroperoxy metabolites by multiple nonenzymatic pathways and initiate cascade reactions yielding reactive aldehyde products, known as 4-hydroxyalkenals (15,16). The peroxidation of AA and LA and of their respective 12- and 15-LO–derived hydroperoxy metabolites results in the generation of 4-hydroxy-2E-nonenal (4-HNE) and/or 4-hydroxy-2E, 6Z-dodecadienal (4-HDDE) (15). Moreover, their formation is enhanced in diabetes as a result of a decrease of the glutathione peroxidase activity (15). Of interest, hyperglycemia promotes the production of these two compounds in diabetic patients and animal models of diabetes (17–19). These 4-hydroxyalkenals exert dual dose-dependent effects in cells; at high levels, they are cytotoxic because of their inherent tendency to form covalent adducts with proteins, DNA, and phospholipids (20). Yet at physiological, nontoxic levels, they act as signaling molecules. Coleman et al. (21) and Riahi et al. (18) have recently found that 4-HNE and 4-HDDE are selective endogenous ligands for peroxisome proliferator–activated receptor-δ (PPAR-δ). Recent reports suggest a role of PPAR-δ in regulating β-cell function; Winzell et al. (22) reported that prolonged treatment of diabetic db/db mice with a PPAR-δ agonist reduced blood glucose levels in association with improved insulin sensitivity and pancreatic islet function. Furthermore, Ravnskjaer et al. (23) attributed to PPAR-δ a fatty acid–sensor role, improving insulin secretion in β-cells.The current study shows increased 4-HNE levels in β-cells exposed to high glucose, coupled to a marked release of AA and LA from membrane phospholipids. This lipid peroxidation product of AA and LA functions as an endogenous ligand for PPAR-δ, augmenting insulin secretion from β-cells. Detrimental effects of high levels of 4-HNE in mediating β-cell damage are also addressed.     

High-resolution melting (HRM) assay for the detection of recurrent BRCA1/BRCA2 germline mutations in Tunisian breast/ovarian cancer families

Germline deleterious mutations in the BRCA1/BRCA2 genes are associated with an increased risk for the development of breast and ovarian cancer. Given the large size of these genes the detection of such mutations represents a considerable technical challenge. Therefore, the development of cost-effective and rapid methods to identify these mutations became a necessity. High resolution melting analysis (HRM) is a rapid and efficient technique extensively employed as high-throughput mutation scanning method. The purpose of our study was to assess the specificity and sensitivity of HRM for BRCA1 and BRCA2 genes scanning. As a first step we estimate the ability of HRM for detection mutations in a set of 21 heterozygous samples harboring 8 different known BRCA1/BRCA2 variations, all samples had been preliminarily investigated by direct sequencing, and then we performed a blinded analysis by HRM in a set of 68 further sporadic samples of unknown genotype. All tested heterozygous BRCA1/BRCA2 variants were easily identified. However the HRM assay revealed further alteration that we initially had not searched (one unclassified variant). Furthermore, sequencing confirmed all the HRM detected mutations in the set of unknown samples, including homozygous changes, indicating that in this cohort, with the optimized assays, the mutations detections sensitivity and specificity were 100 %. HRM is a simple, rapid and efficient scanning method for known and unknown BRCA1/BRCA2 germline mutations. Consequently the method will allow for the economical screening of recurrent mutations in Tunisian population.     

Clinical manifestations of cutaneous metastases: a review with special emphasis on cutaneous metastases mimicking keratoacanthoma

Approximately 5% of oncology patients develop cutaneous metastases, with only a small number of these patients (less than 1%) having metastatic skin lesions as the first sign of their visceral cancer. Metastases tend to occur on skin surfaces in the vicinity of the primary tumor. However, any site may be affected by cutaneous metastases. Skin metastases can present with several morphologies including, albeit rarely, keratoacanthoma-like lesions. Keratoacanthoma is a keratinous tumor that morphologically appears as a nodule with a central keratin-filled crater. This article reviews the characteristics of oncology patients whose cutaneous metastases mimicked a keratoacanthoma, including illustrations from our patient, a 53-year-old Caucasian man whose metastatic esophageal adenocarcinoma not only presented with a keratoacanthoma-like tumor on his upper lip but also a forehead macule and a scalp nodule. We also report keratoacanthoma-like presentations from literature cases of breast cancer, chondrosarcoma, and pulmonary malignancies. The lesions were discovered 3-24 months after diagnosis of visceral cancer and led to the discovery of unsuspected lung cancer in two patients. Most of the patients (60%) died within 2 months of discovery of the keratoacanthoma-like cutaneous metastases. We also reviewed the literature and discuss other morphologies of cutaneous metastases in patients whose primary tumors were in the breast, lung, and esophagus. In addition, we review from the literature other examples of tumors that present as metastatic nodules on the scalp. The possibility of cutaneous metastasis should be entertained and pathologic evaluation should be considered in an oncology patient with underlying visceral malignancy who develops a keratoacanthoma-like lesion.