Alterations in geometry,biomechanics, and mineral composition of juvenile rat femur induced by nonplanar PCB‐155 and/or planar PCB‐169

Exposure to widespread lipophilic and bioaccumulative polychlorinated biphenyls (PCBs) induces diverse biochemical and toxicological responses in various organs, including the bone. The aim of this study was to evaluate the changes in growth rate, geometry, serum, and bone biochemical parameters and biomechanics of juvenile rat femur induced by lactational exposure to nonplanar PCB‐155 and planar PCB‐169 individually and in combination. Fifteen lactating Wistar rats were divided into four groups (PCB‐169, PCB‐155, PCB‐155+169, and control), and PCBs were administered intraperitoneally at different time points after delivery. Femurs from 22‐day‐old offspring were analyzed by microCT, three‐point bending test and inductively coupled plasma‐mass spectrometry (ICP‐MS) to obtain data on bone geometry, biomechanics and mineral composition. The serum levels of calcium, phosphate and alkaline phosphatase were also determined. Lactational exposure to planar PCB‐169 resulted in shorter and thinner femurs, reduced endosteal and periosteal perimeters, smaller total cross‐sectional and medullary areas, and lowered serum bone marker levels and calcium levels in the bone, while femur mechanical properties were not significantly altered. The changes observed in the combination exposure (PCB‐155+169) group were similar to those observed in the PCB‐169 group but were less pronounced. In summary, our results demonstrate that alterations in lactationally exposed offspring were primarily induced by planar PCB‐169. The milder outcome in the combined group suggested that the PCB‐169‐mediated toxic effects on the bone might be reduced by a nonplanar PCB‐155 congener. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1135–1146, 2017.     

Cardiovascular safety of low-dose fenfluramine in Dravet syndrome: a review of its benefit-risk profile in a new patient population

Objective: Dravet syndrome (DS) is a rare, treatment-resistant epilepsy syndrome for which current treatment regimens are often ineffective. Fenfluramine is currently in development for treatment of DS, based on reports in the 1980s and 1990s of its anti-epileptic activity in pediatric patients with intractable epilepsy. However, fenfluramine was withdrawn from global markets in 1997 following reports of its association with pulmonary hypertension and heart valve disease in adult patients treated for obesity. This review was conducted to assess cardiac safety of fenfluramine when used at lower doses for treatment of DS.

Methods: Pubmed was searched for clinical studies of fenfluramine in obese adults who reported incidence of heart valve disease. These data were reviewed against published results from Belgian patients with DS who have been treated with low-dose fenfluramine for up to 28 years.

Results: Nine controlled studies of fenfluramine and related compounds (dexfenfluramine and/or phentermine) which assessed incidence and severity of cardiac valve disease in 3,268 treated patients and 2,017 control subjects have been reported. Mild or greater aortic valve regurgitation was found in 9.6% of treated patients compared with 3.9% of control subjects, and moderate or greater mitral valve regurgitation was found in 3.1% of treated patients and 2.5% of control subjects. Nineteen DS patients have been treated for up to 28 years with 10–20?mg/day fenfluramine, with no clinical signs or symptoms of cardiac valve disease or pulmonary hypertension. Slight and clinically unimportant changes in valve structure have been seen on echocardiography in five patients at some time during the observation period.

Conclusions: A different benefit-risk relationship appears to be emerging when fenfluramine is used at low doses for extended periods in young patients with DS. Continued cardiac assessments during ongoing Phase 3 clinical trials will provide additional safety information for this potential new and effective treatment.     

The effects of sex steroids on thyroid C cells and trabecular bone structure in the rat model of male osteoporosis

Androgen deficiency is one of the major factors leading to the development of osteoporosis in men. Since calcitonin (CT) is a potent antiresorptive agent, in the present study we investigated the effects of androgen deficiency and subsequent testosterone and estradiol treatment on CT-producing thyroid C cells, skeletal and hormonal changes in middle-aged orchidectomized (Orx) rats. Fifteen-month-old male Wistar rats were either Orx or sham-operated (SO). One group of Orx rats received 5 mg kg⁻¹ b.w. testosterone propionate (TP) subcutaneously, while another group was injected with 0.06 mg kg⁻¹ b.w. estradiol dipropionate (EDP) once a day for 3 weeks. A peroxidase–antiperoxidase method was applied for localization of CT in the C cells. The studies included ultrastructural microscopic observation of these cells. The metaphyseal region of the proximal tibia was measured histomorphometrically using an imagej public domain image processing program. TP or EDP treatment significantly increased C cell volume (Vc), volume densities (Vv) and serum CT concentration compared with the Orx animals. Administration of both TP and EDP significantly enhanced cancellous bone area (B.Ar), trabecular thickness (Tb.Th) and trabecular number (Tb.N) and reduced trabecular separation (Tb.Sp). Serum osteocalcin (OC) and urinary Ca concentrations were significantly lower after these treatments in comparison with Orx rats. These data suggest that testosterone and estradiol treatment in Orx middle-aged rats affect calcitonin-producing thyroid C cells, which may contribute to the bone protective effects of sex hormones in the rat model of male osteoporosis.     

Targeting protein-trafficking pathways alters melanoma treatment sensitivity

Protein-trafficking pathways are targeted here in human melanoma cells using methods independent of oncogene mutational status, and the ability to up-regulate and down-regulate tumor treatment sensitivity is demonstrated. Sensitivity of melanoma cells to cis-diaminedichloroplatinum II (cDDP, cis-platin), carboplatin, dacarbazine, or temozolomide together with velaparib, an inhibitor of poly (ADP ribose) polymerase 1, is increased by up to 10-fold by targeting genes that regulate both protein trafficking and the formation of melanosomes, intracellular organelles unique to melanocytes and melanoma cells. Melanoma cells depleted of either of the protein-trafficking regulators vacuolar protein sorting 33A protein (VPS33A) or cappuccino protein (CNO) have increased nuclear localization of cDDP, increased nuclear DNA damage by platination, and increased apoptosis, resulting in increased treatment sensitivity. Depleted cells also exhibit a decreased proportion of intracellular, mature melanosomes compared with undepleted cells. Modulation of protein trafficking via cell-surface signaling by binding the melanocortin 1 receptor with the antagonist agouti-signaling protein decreased the proportion of mature melanosomes formed and increased cDDP sensitivity, whereas receptor binding with the agonist melanocyte-stimulating hormone resulted in an increased proportion of mature melanosomes formed and in decreased sensitivity (i.e., increased resistance) to cDDP. Mutation of the protein-trafficking gene Hps6, known to impair the formation of mature melanosomes, also increased cDDP sensitivity. Together, these results indicate that targeting protein-trafficking molecules markedly increases melanoma treatment sensitivity and influences the degree of melanosomes available for sequestration of therapeutic agents.     

Statins do not Increase the Rate of Bleeding Among Warfarin Users

Clinical significance of potential interaction between warfarin and statins is unclear. Our objective was to determine whether use of statins as a class or use of simvastatin modulates the rate of bleeding requiring hospitalization among new warfarin users. Using Finnish healthcare databases, we identified a cohort of 101,588 warfarin initiators between 1 January 2009 and 30 June 2012. By the end of 2012, these patients accumulated 92,695 person‐years of exposure to warfarin‐only and 60,253 years of exposure to warfarin‐with‐statin. The outcome was a composite of gastrointestinal, intracranial or other bleeding leading to hospitalization. A Poisson generalized estimating equation model was employed to estimate rate ratios (RR) and their 95% confidence intervals (CI) for exposure to warfarin‐with‐statin compared to warfarin‐only and to allow multiple episodes per patient and time‐dependent covariates. In multivariable models, we found no difference in the bleeding rate in association with exposure to any statin (multivariable‐adjusted RR = 0.98, 95% CI 0.89–1.07) or to simvastatin (RR = 1.01, 95% CI 0.91–1.11) with warfarin compared to exposure to warfarin‐only. We conclude that concomitant use of statins and warfarin was not associated with an increased rate of bleeding requiring hospitalization.     

Neurogenesis and gliogenesis in the spinal cord of turtles

A 5-bromo-3'-deoxyuridine (BrdU) pulse administered to juvenile turtles resulted in cell labeling throughout the gray matter (GM) and white matter (WM) of the spinal cord. One and twenty-four hours postinjection, larger densities of BrdU-labeled nuclei (LN) occurred within the GM, with a density peak localized in the central region (CR). Seven days later, density differences between GM and WM disappeared, accompanying a more uniform distribution of LN in the GM (absence of the central peak). Multiple injection experiments also showed similar evolution in the distribution of LN. Morphometric studies revealed that the size of LN had undergone time-related increments: Larger nuclei appeared at protracted fixation time points. Double-labeling experiments indicated that BrdU-labeled cells expressed neuroactive substances, such as gamma-aminobutyric acid (GABA), neuron-specific nuclear protein (NeuN), and the cytoplasmic early postmitotic neuronal marker (TUC-4). Other BrdU-labeled cells expressed the glial-specific protein (GFAP). GABA-BrdU, TUC-4-BrdU, and GFAP-BrdU double-labeled cells were recognized 6 days after the first BrdU injection. NeuN-BrdU double-labeled cells were found at 50 days postinjection. Three-dimensional transmission electron microscopy revealed the presence of synapses and typical kinocilia in putative immature nerve cells. Kinocilia were also found in putative immature glial cells. In consideration of the scattered distribution pattern of BrdU-labeled cells, in animals fixed 1 hour postinjection, the existence of a single proliferating center was discarded. The CR, including the ependymal epithelium, showed the highest density of LN.     

Spectral analysis of cerebellar activity after acute brain injury in anesthetized rats

We investigated cerebellar electrocortical activity before and after unilateral brain injury in anesthetized rats. Spectral analysis of cerebellar activity was obtained by Fast Fourier Transformation. There was a dominance of delta frequency range, while the wide gamma range presented no more than 5% of the total mean power spectra of cerebellar activity before brain injury. A few minutes after brain injury and within the first 90 minutes, there was a decrease of total mean power spectra and a relative decrease of delta range power to about 30%, some increase of beta range, and an increase of gamma range to 20-25%. Relative increase of gamma range in the cerebellar mean power spectra was still present 120 min after the brain injury, while other changes started to diminish. We suggest that spectral changes within slow and fast (gamma) frequency ranges of cerebellar activity may be indicators of the brain state after acute injury.