Hippocampal–Prefrontal BDNF and Memory for Fear Extinction

Infusing brain-derived neurotrophic factor (BDNF) into the infralimbic (IL) prefrontal cortex is capable of inducing extinction. Little is known, however, about the circuits mediating BDNF effects on extinction or the extent to which extinction requires BDNF in IL. Using local pharmacological infusion of BDNF protein, or an antibody against BDNF, we found that BDNF in the IL, but not prelimbic (PL) prefrontal cortex, is both necessary and sufficient for fear extinction. Furthermore, we report that BDNF in IL can induce extinction of older fear memories (14 days) as well as recent fear memories (1 day). Using immunocytochemistry, we show that BDNF is increased in the ventral hippocampus (vHPC), but not IL or PL, following extinction training. Finally, we observed that infusing BDNF into the vHPC increased the firing rate of IL, but not PL neurons in fear conditioned rats. These findings indicate that an extinction-induced increase in BDNF within the vHPC enhances excitability in IL targets, thereby supporting extinction memories.     

“Designer Genes and the Politics of Fear”

Abstract

The recent large commitment of capital and personnel to biotechnology by multi national corporations is evidence that management believes scientists can develop a wide range of products for human and animal health and the production of crops. Yet current food surpluses create an atmosphere wherein actions taken by those who fear the development of biotechnology have succeeded in halting planned experiments and popularized accounts of vast public danger. Thus, the regulatory process for biotechnology is one of the major challenges facing society.

There is need for leadership by industry to present fact, correct misimpressions, debate issues, and to be as dedicated to resolution of the regulatory aspects of biotechnology as to the development of the science itself.     

A Role for Bioelectric Effects in the Induction of Bystander Signals by Ionizing Radiation?

The induction of "bystander effects" i.e. effects in cells which have not received an ionizing radiation track, is now accepted but the mechanisms are not completely clear. Bystander effects following high and low LET radiation exposure are accepted but mechanisms are still not understood. There is some evidence for a physical component to the signal. This paper tests the hypothesis that bioelectric or biomagnetic phenomena are involved. Human immortalized skin keratinocytes and primary explants of mouse bladder and fish skin, were exposed directly to ionizing radiation or treated in a variety of bystander protocols. Exposure of cells was conducted by shielding one group of flasks using lead, to reduce the dose below the threshold of 2mGy (60)Cobalt gamma rays established for the bystander effect. The endpoint for the bystander effect in the reporter system used was reduction in cloning efficiency (RCE). The magnitude of the RCE was similar in shielded and unshielded flasks. When cells were placed in a Faraday cage the magnitude of the RCE was less but not eliminated. The results suggest that liquid media or cell-cell contact transmission of bystander factors may be only part of the bystander mechanism. Bioelectric or bio magnetic fields may have a role to play. To test this further, cells were placed in a Magnetic Resonance Imaging (MRI) machine for 10 min using a typical head scan protocol. This treatment also induced a bystander response. Apart from the obvious clinical relevance, the MRI results further suggest that bystander effects may be produced by non-ionizing exposures. It is concluded that bioelectric or magnetic effects may be involved in producing bystander signaling cascades commonly seen following ionizing radiation exposure.     

Engineering the niche for hair regeneration — A critical review

Recent progress in hair follicle regeneration and alopecia treatment necessitates revisiting the concepts and approaches. In this sense, there is a need for shedding light on the clinical and surgical therapies benefitting from nanobiomedicine. From this perspective, this review attempts to recognize requirements upon which new hair therapies are grounded; to underline shortcomings and opportunities associated with recent advanced strategies for hair regeneration; and most critically to look over hair regeneration from nanomaterials and pluripotent stem cell standpoint. It is noteworthy that nanotechnology is able to illuminate a novel path for reprogramming cells and controlled differentiation to achieve the desired performance. Undoubtedly, this strategy needs further advancement and a lot of critical questions have yet to be answered. Herein, we introduce the salient features, the hurdles that must be overcome, the hopes, and practical constraints to engineer stem cell niches for hair follicle regeneration.     

Alopecia areata and the gut—the link opens up for novel therapeutic interventions

Introduction: This review aims to raise the potential of the modern society’s impact on gut integrity often leading to increased intestinal permeability, as a cause or driver of Alopecia Areata (AA) in genetically susceptible people. With the increasing rate of T cell-driven autoimmunity, we hypothesize that there is a common root cause of these diseases that originates from chronic inflammation, and that the gut is the most commonly exposed area with our modern lifestyle.

Areas covered: We will discuss the complexity in the induction of AA and its potential link to increased intestinal permeability. Our main focus will be on the gut microbiome and mechanisms involved in the interplay with the immune system that may lead to local and/or peripheral inflammation and finally, tissue destruction.

Expert opinion: We have seen a link between AA and a dysfunctional gastrointestinal system which raised the hypothesis that an underlying intestinal inflammation drives the priming and dysregulation of immune cells that lead to hair follicle destruction. While it is still important to resolve local inflammation and restore the IP around the hair follicles, we believe that the root cause needs to be eradicated by long-term interventions to extinguish the fire driving the disease.     

Microdialysis for the evaluation of penetration through the human skin barrier — a promising tool for future research?

The direct measurement of local drug concentration levels at discreet skin locations with minor trauma has recently become possible with the introduction of cutaneous microdialysis. Cutaneous microdialysis is an in vivo sampling technique for measuring solutes in the extracellular fluid of the dermis. When used in combination with other experimental approaches, for example with a variety of non-invasive techniques to describe the functional status of the skin (bioengineering methods), it may help investigators to gain new insights into the fields of skin diseases, metabolism and drug absorption/penetration. An important parameter to describe the efficacy of microdialysis is the relative recovery. This is the ratio between the concentration of a substance in the dialysate and the true extracellular concentration. Several methods are in common use to describe the relative recovery (no-net-flux method or retrodialysis). Parameters such as probe design, depth of the probe in the dermis, physico-chemical properties of the compound of interest, and analytical aspects are important factors influencing microdialysis. Microdialysis has been used to investigate the influence of penetration enhancers, vehicles or iontophoresis on percutaneous absorption, performed by in vivo studies in rats. In human volunteers, most of the experiments have been performed to study the kinetics of fast penetrating substances, e.g. nicotine, non-steroidal antiinflammatory drugs, local anaesthetics, or solvents. Problems have been encountered in the detection of lipophilic and highly protein-bound substances. Further, dermal metabolism and the influence of barrier perturbation on percutaneous absorption have been analyzed. Investigations suggest that microdialysis, in combination with traditional techniques, might give valuable information regarding the assessment of the penetration of drugs and other exogenous agents through the skin. In spite of the clearly defined and accepted advantages of microdialysis technology for studies of transdermal drug delivery, to date no standardized test procedure exists nor has the reproducibility of the results been evaluated. In the future, these problems have to be solved to enable this method to find its place in standard research.     

Overexpression of Protein Kinase Mζ in the Prelimbic Cortex Enhances the Formation of Long-Term Fear Memory

Neuroplasticity in the prefrontal cortex (PFC) after fear conditioning has been suggested to regulate the formation and expression of fear memory. Protein kinase Mζ (PKMζ), an isoform of protein kinase C with persistent activity, is involved in the formation and maintenance of memory. However, less is known about the role of PKMζ in the PFC in the formation of fear memory. We investigated whether the overexpression of PKMζ enhances the formation of auditory fear memory in rats. We found that microinfusion of lentiviral vector-expressing PKMζ into the prelimbic cortex (PrL) selectively enhanced the expression of PKMζ without influencing the expression of other isoforms of PKC. The overexpression of PKMζ in the PrL enhanced the formation of long-term fear memory without affecting short-term fear memory, whereas the overexpression of PKMζ in the infralimbic cortex had no effect on either short-term or long-term fear memory. The overexpression of PKMζ in the PrL had no effect on anxiety-like behavior or locomotor activity. We also found that PKMζ overexpression potentiated the fear conditioning-induced increase in the membrane levels of glutamate subunit 2 of AMPA receptors in the PrL. These results demonstrate that the overexpression of PKMζ in the PrL but not infralimbic cortex selectively enhanced the formation of long-term fear memory, and PKMζ in the PrL may be involved in the formation of fear memory.     

A Mechanism for Hormesis — A Problem in the Wrong Discipline

The wealth of examples of hormesis exhibiting the beta curve leave little doubt as to the generality of the phenomenon. However, its full acceptance requires a satisfactory theoretical basis to account for the diversity of instances of hormesis; without it the concept has little meaning beyond what is obvious from the defining beta curve. It has been proposed that a homeostatic hypothesis is the most plausible and is gaining support. However, there is a need to involve researchers in other disciplines than toxicology to identify physiological mechanisms to account for it, whereupon hormesis can begin to gain wider recognition and fulfill its potential in pure and applied science.

Normal science… often suppresses fundamental novelties because they are necessarily subversive of its basic commitments.

Thomas S. Kuhn 1962

Every novel idea….must, before it wins general acceptance, pass through three stages. It is, to begin with, repudiated as absurd. After that it is allowed to be reasonable. And, finally, it is belittled as obvious.

Almroth Wright (1861–1947)     

Venous thromboembolism in pregnant woman — a challenge for the clinician

Deep vein thrombosis and pulmonary embolism are two clinical entities of a single disease called venous thromboembolism. Venous thromboembolism is an important cause of maternal morbidity and mortality. Diagnosis and treatment of venous thromboembolism in pregnant women are much more difficult than in non-pregnant women. Pregnant patients were excluded from all major clinical trials investigating therapeutic combinations for acute thromboembolism. Although, for many years, the standard anticoagulant during pregnancy and postpartum was unfractionated heparin, current guidelines recommend low molecular weight heparin. The advantages of low molecular weight heparin are lower risk of bleeding, predictable pharmacokinetics, lower risk of fracture because of thrombocytopenia and heparin-induced osteoporosis.     

Transdisciplinary Collaboration as a Basis for Enhancing the Science and Prevention of Substance Use and “Abuse”

Transdisciplinary scientific collaborations (TDSCs) have the potential to strengthen substance use and misuse research and prevention. Despite its growing prominence as a mode for scientific research, research on TDSC remains in a nascent form and its value to the field of substance use and misuse merits further exploration. The overarching purpose of this article is to examine the potential contributions of transdisciplinary science to research and prevention using conceptualizations, methods, and evidence from a case study of two university-based research centers. The article provides (a) a discussion of the societal context and historical developments that have prompted increasing interest in TDSC; (b) a definition and conceptualization of TDSC; (c) a methodological approach for studying TDSC; (d) initial findings from the case study that reflect instances of transdisciplinary intellectual integration and it examines implications of these methods and findings for future research and policy development relevant to substance use and misuse.     

Aquatic toxicity tests for the control of effluent discharges in the UK — the influence of test precision

The initiative by the River Purification Boards (RPBs), National Rivers Authority (NRA) and Her Majesty's Inspectorate of Pollution (HMIP) to control certain complex and toxic effluent discharges by direct toxicity assessment places great emphasis on the use of aquatic toxicity tests. Like all biological and analytical measurements, determinations of toxicity exhibit variability. When setting Toxicity-based Consents (TBCs) and monitoring for compliance with such consents, it is important to understand and if possible control this variability. The implications of toxicity test variability for the way TBCs may be set and monitored are discussed; including a consideration of monitoring consents based on a single exposure concentration (limit) test and procedures involving a range of exposure concentrations (concentration-response test). We also review the precision of data arising from acute aquatic toxicity test methods which may be used for the control and monitoring of complex effluents in the UK. This includes the variability that occurs when repeated tests are carried out on different occasions within the same laboratory (repeatability) and also within different laboratories (reproducibility). Particular attention is given to acute tests using Daphnia magna, the only method for which there is a large amount of published information on the precision of toxicity data.     

Pharmacokinetic Interactions for Drugs with a Long Half-Life—Evidence for the Need of Model-Based Analysis

Pharmacokinetic drug-drug interactions (DDIs) can lead to undesired drug exposure, resulting in insufficient efficacy or aggravated toxicity. Accurate quantification of DDIs is therefore crucial but may be difficult when full concentration-time profiles are problematic to obtain. We have compared non-compartmental analysis (NCA) and model-based predictions of DDIs for long half-life drugs by conducting simulation studies and reviewing published trials, using antituberculosis drug bedaquiline (BDQ) as a model compound. Furthermore, different DDI study designs were evaluated. A sequential design mimicking conducted trials and a population pharmacokinetic (PK) model of BDQ and the M2 metabolite were utilized in the simulations where five interaction scenarios from strong inhibition (clearance fivefold decreased) to strong induction (clearance fivefold increased) were evaluated. In trial simulations, NCA systematically under-predicted the DDIs’ impact. The bias in average exposure was 29–96% for BDQ and 20–677% for M2. The model-based analysis generated unbiased predictions, and simultaneous fitting of metabolite data increased precision in DDI predictions. The discrepancy between the methods was also apparent for conducted trials, e.g., lopinavir/ritonavir was predicted to increased BDQ exposure 22% by NCA and 188% by model-based methods. In the design evaluation, studies with parallel designs were considered and shown to generally be inferior to sequential/cross-over designs. However, in the case of low inter-individual variability and no informative metabolite data, a prolonged parallel design could be favored. Model-based analysis for DDI assessments is preferable over NCA for victim drugs with a long half-life and should always be used when incomplete concentration-time profiles are part of the analysis.

Electronic supplementary material

The online version of this article (doi:10.1208/s12248-015-9829-2) contains supplementary material, which is available to authorized users.KEY WORDS: drug-drug interactions, long half-life, model-based analysis, non-compartmental analysis, pharmacokinetics     

Gap-Freezing Approach for Shortening the Lyophilization Cycle Time of Pharmaceutical Formulations—Demonstration of the Concept

During gap freezing, vials are placed on a metal tray, which is separated from the shelf surface with a small air gap that eliminates significant conductive heat transfer from the shelf to the bottom of the vial. The purpose of this freezing approach is to reduce the lyophilization cycle time of various amorphous formulations by nearly isothermal freezing. Such isothermal freezing promotes the formation of large ice crystals, and thus large pores throughout the cake, which subsequently accelerates the primary drying rate. The nucleation temperature using gap freezing, for the experimental conditions tested, was in the range of ? 1°C to ? 6°C, much higher than the range of ? 10°C to ? 14°C found using conventional shelf freezing. Isothermal freezing becomes effective when the gap is greater than 3 mm. The pore sizes and cake resistance during primary drying for various formulations were determined using the pore diffusion model developed by Kuu et al. (Pharm Dev Technol, 2011, 16(4): 343-357). Reductions in primary drying time were 42% (for 10% sucrose), 45% (for 10% trehalose), and 33% (for 5% sucrose). © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:2572–2588, 2013