Silver nanoparticles disrupt GDNF/Fyn kinase signaling in spermatogonial stem cells

Silver nanoparticles (Ag-NPs) are being utilized in an increasing number of fields and are components of antibacterial coatings, antistatic materials, superconductors, and biosensors. A number of reports have now described the toxic effects of silver nanoparticles on somatic cells; however, no study has examined their effects on the germ line at the molecular level. Spermatogenesis is a complex biological process that is particularly sensitive to environmental insults. Many chemicals, including ultrafine particles, have a negative effect on the germ line, either by directly affecting the germ cells or by indirectly acting on the somatic cells of the testis. In the present study, we have assessed the impact of different doses of Ag-NPs, as well as their size and biocompatible coating, on the proliferation of mouse spermatogonial stem cells (SSCs), which are at the origin of the germ line in the adult testis. At concentrations >OR= 10 microg/ml, Ag-NPs induced a significant decline in SSCs proliferation, which was also dependent on their size and coating. At the concentration of 10 microg/ml, reactive oxygen species production and/or apoptosis did not seem to play a major role; therefore, we explored other mechanisms to explain the decrease in cell proliferation. Because glial cell line-derived neurotrophic factor (GDNF) is vital for SSC self-renewal in vitro and in vivo, we evaluated the effects of Ag-NPs on GDNF-mediated signaling in these cells. Although the nanoparticles did not reduce GDNF binding or Ret receptor activity, our data revealed that already at a concentration of 10 microg/ml, silver nanoparticles specifically interact with Fyn kinase downstream of Ret and impair SSC proliferation in vitro. In addition, we demonstrated that the particle coating was degraded upon interaction with the intracellular microenvironment, reducing biocompatibility.

Efficient delivery of intact phosphodiester oligonucleotides by poly-beta-amino esters

Due to their great instability, phosphodiester antisense oligonucleotides (PO-ODNs) are rapidly degraded in the intracellular environment, which limits their biological activity. The release of PO-ODNs during a prolonged period of time could however greatly enhance their antisense effect by creating a pool of intact PO-ODNs at any time point. Poly-beta-aminoesters are biodegradable cationic polymers which show potential for the controlled release of short DNA fragments like ODNs and small interfering RNA (siRNA). In this research we evaluated biodegradable poly-beta-aminoesters as carriers for PO-ODNs and compared the antisense activity with nuclease stable phosphothioate (PS) ODNs. PBAE1 polymers were not able to generate an antisense effect with PO- or PS-ODNs, most likely due to their poor cellular uptake. When complexed to PBAE2 polymers at N/P ratio 10, both PO- and PS-ODNs downregulated the targeted protein expression with 70%. By confocal imaging we observed a high concentration of released PO-ODNs that formed nuclear bodies in the nucleoplasm. The ODNs in these nuclear bodies were still intact as could be demonstrated by Fluorescence Resonance Energy Transfer (FRET) and acceptor photobleaching. This was in clear contrast to PO-ODNs delivery by cationic liposomes where the ODNs that accumulated in the nucleus were degraded and nuclear bodies were not observed. We conclude that PBAE2 shows potential for the delivery of nuclease sensitive PO-ODNs. This occurs however not through a time controlled release profile, but rather due to the rapid delivery of a high concentration of intact PO-ODNs that form nuclear bodies in the nuclei of the cells. These nuclear bodies can most likely act as a depot of intact PO-ODNs, resulting in efficient antisense activity.

[Uterine sarcoma associated with tamoxifen use after breast cancer: Review of the pathogenesis]

Tamoxifen is widely used in the breast cancer treatment. Its side effects on the endometrium are well-known, but more and more worse prognosis uterine sarcoma are described. Based on recent literature review, the cause and effect chain between tamoxifen and uterine sarcoma is argued, which confirms that a risk exists as from 2 years of treatment, a cumulative dose of 15 g, and that malignant mixed mesodermal tumours appear to be the most frequent.

Signaling pathways in spermatogonial stem cells and their disruption by toxicants

Spermatogenesis is a complex biological process that is particularly sensitive to environmental insults such as chemicals and physical stressors. Exposure to specific chemicals has been shown to inhibit fertility through a negative impact on germ cell proliferation and differentiation that can lower sperm count. In addition, toxicants might produce DNA damages that could have negative consequences on the development of the offspring. This review describes spermatogonial stem cell development in the testis, signaling pathways that are crucial for self-renewal, and possible target molecules for environmental toxicants such as phthalate esters and nanoparticles.

Inter-hemispheric asymmetry of motor corticospinal excitability in major depression studied by transcranial magnetic stimulation

BACKGROUND

Imaging and electroencephalographic studies have reported inter-hemispheric asymmetries in frontal cortical regions associated with depression. This study aimed at comparing motor corticospinal excitability assessed by methods of transcranial magnetic stimulation (TMS) between the right and left hemispheres in patients with major depression and healthy controls.

METHOD

Patients with major depression (n=35) and healthy controls (n=35) underwent a bilateral study of various motor corticospinal excitability parameters, including rest motor threshold (RMT), corticospinal silent period (CSP) duration and intra-cortical inhibition (ICI) and facilitation (ICF). Indexes of asymmetry were calculated, and the relationships between excitability parameters and clinical scores of depression were statistically analyzed.

RESULTS

Depressed patients showed a reduced excitability of both excitatory (RMT, ICF) and inhibitory (CSP, ICI) processes in the left hemisphere, compared to the right hemisphere and to healthy controls.

CONCLUSION

The present results confirmed the existence of inter-hemispheric asymmetries in frontal cortex activities of depressed patients in favor of a left-sided reduced excitability. This neurophysiological approach may help to guide repetitive TMS procedures in the treatment of depressive disorders.

Mental health nurse supplementary prescribing: experiences of mental health nurses, psychiatrists and patients

AIM

This paper is a report of a study to explore the views of patients, mental health nurses and psychiatrists involved in mental health nurse supplementary prescribing.

BACKGROUND

Medication prescribing by mental health nurses in the United Kingdom is controversial. However, the experience of mental health patients suggests that increasing prescribing capacity could be one strategy to provide a person-centred prescribing approach.

METHOD

A qualitative study was carried out in 2005. Semi-structured interviews were conducted with 12 psychiatrists, 11 mental health nurses with prescribing authority, and 12 patients who had been prescribed psychiatric medication by a mental health nurse. Participants were interviewed about positive aspects of supplementary prescribing including the extent of it being evidence-based, person-centred and clinically focussed.

FINDINGS

Participants from all three groups had a positive reaction to nurse supplementary prescribing. Mental health nurse prescribing was viewed as evidence-based, person-centred and with an additional focus on physical health. Mental health nurses worked within their levels of competency. Barriers to the implementation of mental health nurse prescribing were nurses' lack of prescribing experience, shortfalls in supervision, insufficient focus on redesigning the service to support the role of the mental health nurse, and preparation for the role.

CONCLUSION

Mental health nurse prescribing seems potentially beneficial. However, more rigorous audit and evaluation are needed to confirm its safety, patient satisfaction and health outcomes. Mental health nurse prescribing will require service redesign to ensure that is becomes embedded in the service organizational culture.

Le carcinosarcome ovarien

Ovarian carcinosarcoma, also called malignant mixed mesodermal tumour, is a rare ovarian tumour representing less than two per cent of ovarian cancers. Carcinosarcoma is an aggressive tumour, which associates some epithelial elements (carcinoma) with a stromal component (sarcoma). This tumour can be found in the female genital tractus, mostly in the uterus. It can be found even more rarely on the ovaries. The initial stage of the disease at the diagnostic is considered as the only prognostic factor. There is no existing consensus concerning treatment. Nevertheless, surgical treatment is paramount for the survival of patients. Response rates to chemotherapy are about 20%.

Can we better understand the intracellular behavior of DNA nanoparticles by fluorescence correlation spectroscopy?

The use of non-viral gene carriers to deliver small nucleic acids like antisense oligonucleotides (ODNs) and small interfering RNA (siRNA) remains an attractive but challenging goal in antisense therapy. Indeed, different barriers need to be overcome in the delivery process before a therapeutic effect can be obtained. One promising technique which we have been evaluating to improve our understanding of the intracellular behavior of nucleic acids/carrier complexes is Fluorescence Correlation Spectroscopy (FCS). In particular, we have used FCS for studying the protection of the nucleic acids against enzymatic degradation, and the association and dissociation of the nucleic acids with their carrier, both in buffer and in living cells. In this report, we will review our experience and findings on the use of FCS for that purpose and discuss the strengths and weaknesses of this interesting technique.

Protection of oligonucleotides against enzymatic degradation by pegylated and nonpegylated branched polyethyleneimine

Among the cationic polymers, polyethyleneimine (PEI) is a promising candidate for delivery of oligodeoxynucleotides (ODNs). In this study, we wondered whether pegylation of PEI influences the complexation with ODNs. We especially aimed to investigate whether ODNs are differently protected against enzymatic degradation in PEI and polyethylene glycol-polyethyleneimine (PEG-PEI) polyplexes. Using fluorescence resonance energy transfer combined with fluorescence correlation spectroscopy, we found that PEI/ODN polyplexes remain to protect the ODNs they carry over a prolonged period of time while in PEG-PEI/ODN polyplexes the degradation of the ODNs slowly proceeds. We attribute this to the fact that PEI seems to compact the ODNs more firmly in the polyplexes' core than PEG-PEI, which apparently also results in a better protection against enzymatic degradation. These observations may also influence the efficiency of PEI-based ODN delivery in vivo, where pegylation is an attractive strategy to enhance the stability of the polyplexes in the blood stream.

[Influenza A/H5N1 virus outbreaks and prepardness to avert flu pandemic]

This review emphasizes the need to improve the knowledge of the biology of H5N1 virus, a candidate for causing the next influenza pandemic. In-depth knowledge of mode of infection, mechanisms of pathogenesis and immune response will help in devising an efficient and practical control strategy against this flu virus. We have discussed limitations of currently available vaccines and proposed novel approaches for making better vaccines against H5N1 influenza virus. They include cell-culture system, reverse genetics, adjuvant development. Our review has also underscored the concept of therapeutic vaccine (anti-disease vaccine), which is aimed at diminishing 'cytokine storm' seen in acute respiratory distress syndrome and/or hemophagocytosis.

Characterization of neutral fragments issued from the photodissociation of protonated tryptophane

New information on the photo-fragmentation of biomolecules is obtained from the detection of neutral and ionic fragments using a time and position resolved coincidence technique that reveals whether an ionic photofragment is associated with one or more neutral fragments. In the case of a sequential dissociation, both fragmentation channels are identified as well as their time ordering.