Impregnation of bone chips with antibiotics and storage of antibiotics at different temperatures: an in vitro study

<p>Abstract</p> <p>Background</p> <p>Allograft bone used in joint replacement surgery can additionally serve as a carrier for antibiotics and serve as a prophylaxis against infections. However, <it>in vitro </it>dose-response curves for bone chips impregnated with different kinds of antibiotics are not available. In addition, while it would be desirable to add the antibiotics to allograft bone chips before these are stored in a bone bank, the effects of different storage temperatures on antibiotics are unknown.</p> <p>Methods</p> <p>Five different antibiotics (cefazolin, clindamycin, linezolid, oxacillin, vancomycin) were stored, both as pills and as solutions, at -80°C, -20°C, 4°C, 20°C and 37°C; in addition, bone chips impregnated with cefazolin and vancomycin were stored at -80°C and -20°C. After 1 month, 6 months and 1 year, the activity of the antibiotics against <it>Staphylococcus epidermidis </it>was measured using an inoculated agar. The diameter of the <it>S. epidermidis</it>-free zone was taken as a measure of antibiotic activity.</p> <p>In a separate experiment, <it>in vitro </it>dose-response curves were established for bone chips impregnated with cefazolin and vancomycin solutions at five different concentrations.</p> <p>Finally, the maximum absorbed amounts of cefazolin and vancomycin were established by impregnating 1 g of bone chips with 5 ml of antibiotic solution.</p> <p>Results</p> <p>A decrease of the <it>S. epidermidis</it>-free zone was seen with oxacillin and cefazolin solutions stored at 37°C for 1 month, with vancomycin stored at 37°C for 6 months and with cefazolin and oxacillin solutions stored at 20°C for 6 months. The activity of the other antibiotic solutions, pills and impregnated bone chips was not affected by storage. The <it>in vitro </it>dose-response curves show that the free-zone diameter increases logarithmically with antibiotic concentration. The absorbed antibiotic amount of one gram bone chips was determined.</p> <p>Conclusions</p> <p>Storage of antibiotics in frozen form or storage of antibiotic pills at temperatures up to 37°C for 12 months does not affect their activity. However, storage of antibiotic solutions at temperatures above 20°C does affect the activity of some of the antibiotics investigated. The <it>in vitro </it>dose-response curve can be used to determine the optimal concentration(s) for local application. It provides the opportunity to determine the antibiotic content of bone chips, and thus the amount of antibiotics available locally after application.</p

Identification of the PS1 Thr147Ile Variant in a Family with Very Early Onset Dementia and Expressive Aphasia

Background: Early onset dementias have variable clinical presentations and are often difficult to diagnose. We established a family pedigree that demonstrated consistent recurrence of very early onset dementia in successive generations. Objective and Method: In order to refine the diagnosis in this family, we sequenced the exomes of two affected family members and relied on discrete filtering to identify disease genes and the corresponding causal variants. Results: Among the 720 nonsynonymous single nucleotide polymorphisms (SNPs) shared by two affected members, we found a C to T transition that gives rise to a Thr147Ile missense substitution in the presenilin 1 (PS1) protein. The presence of this same mutation in a French early-onset Alzheimer’s disease family, other affected members of the family, and the predicted high pathogenicity of the substitution strongly suggest that it is the causal variant. In addition to exceptionally young age of onset, we also observed significant limb spasticity and early loss of speech, concurrent with progression of dementia in affected family members. These findings extend the clinical presentation associated with the Thr147Ile variant. Lastly, one member with the Thr147Ile variant was treated with the PKC epsilon activator, bryostatin, in a compassionate use trial after successful FDA review. Initial improvements with this treatment were unexpectedly clear, including return of some speech, increased attentional focus, ability to swallow, and some apparent decrease in limb spasticity. Conclusions: Our findings confirm the role of the PS1 Thr147Ile substitution in Alzheimer’s disease and expand the clinical phenotype to include expressive aphasia and very early onset of dementia

Cut-Off Points for Mild, Moderate, and Severe Pain on the Numeric Rating Scale for Pain in Patients with Chronic Musculoskeletal Pain: Variability and Influence of Sex and Catastrophizing

Objectives. The 0 – 10 Numeric Rating Scale (NRS) is often used in pain management. The aims of our study were to determine the cut-off points for mild, moderate and severe pain in terms of pain-related interference with functioning in patients with chronic musculoskeletal pain, to measure the variability of the optimal cut-off points, and to determine the influence of patients’ catastrophizing and their sex on these cut-off points. Methods. 2854 patients were included. Pain was assessed by the NRS, functioning by the Pain Disability Index (PDI) and catastrophizing by the Pain Catastrophizing Scale (PCS). Cut-off point schemes were tested using ANOVAs with and without using the PSC scores or sex as co-variates and with the interaction between CP scheme and PCS score and sex, respectively. The variability of the optimal cut-off point schemes was quantified using bootstrapping procedure. Results and conclusion. The study showed that NRS scores ≤5 correspond to mild, scores of 6-7 to moderate and scores ≥8 to severe pain in terms of pain-related interference with functioning. Bootstrapping analysis identified this optimal NRS cut-off point scheme in 90 % of the bootstrapping samples. The interpretation of the NRS is independent of sex, but seems to depend on catastrophizing. In patients with high catastrophizing tendency, the optimal cut-off point scheme equals that for the total study sample, but in patients with a low catastrophizing tendency, NRS scores ≤3 correspond to mild, scores of 4-6 to moderate and scores ≥7 to severe pain in terms of interference with functioning. In these optimal cut-off schemes, NRS scores of 4 and 5 correspond to moderate interference with functioning for patients with low catastrophizing tendency and to mild interference for patients with high catastrophizing tendency. Theoretically one would therefore expect that among the patients with NRS scores 4 and 5 there would be a higher average PDI score for those with low catastrophizing than for those with high catastrophizing. However, we found the opposite. The fact that we did not find the same optimal CP scheme in the subgroups with lower and higher catastrophizing tendency may be due to chance variability

Oxidative Stress Responses to Simulated Spaceflight in Mineralized and Marrow Compartments of Bone and Associated Vasculature

Long-term spaceflight causes profound changes to the musculoskeletal system attributable to unloading and fluid shifts in microgravity. Future space explorations beyond the earths magnetosphere will expose astronauts to space radiation, which may cause additional skeletal deficits that are not yet fully understood. Our long-term goals are twofold: to define the mechanisms and risk of bone loss in the spaceflight environment and to facilitate the development of effective countermeasures if necessary. Our central hypothesis is that oxidative stress plays a key role in progressive bone loss and vascular dysfunction caused by spaceflight. In animals models, overproduction of free radicals is associated with increased bone resorption, lower bone formation, and decrements in bone mineral density and structure which can ultimately lead to skeletal fragility. Evidence in support of a possible causative role for oxidative stress in spaceflight-induced bone loss derive from knockout and transgenic mouse studies and the use of pharmacological interventions with known anti-oxidant properties. In our studies to simulate spaceflight, 16-wk old, male C56Bl/6J mice were assigned to one of four groups: hind limb unloading to simulate weightlessness (HU), normally loaded Controls (NL) (sham irradiated, no hind limb unloading), irradiated at NASA Space Radiation Laboratory IR with 1-2Gy of (600MeV/n) alone, or in combination with protons (0.5Gy Protons/0.5Gy 56Fe), (IR) or both hind limb unloaded and irradiated, HU+IR. Mice were exposed to radiation 3 days after initiating HU and tissues harvested were 1-14 days after initiating treatments for analyses. Results from our laboratories, which employ various biochemical, gene expression, functional, and transgenic animal model methods, implicate dynamic regulation of redox-related pathways by spaceflight-related environmental factors. As one example, we found that combined HU and radiation exposure caused oxidative damage in skeletal tissues (lipid peroxidation) of wildtype mice, whereas bone from transgenic mice that overexpress human catalase in mitochondria were protected. Interestingly, marrow cells grown under culture conditions that select for endothelial progenitor cells (EPC), showed that HU but not IR reduced EPC cell migration; in contrast HU and IR each inhibited growth of marrow-derived osteoblast progenitors. Taken together, these results indicate that unloading and ionizing elicit distinct effects on progenitor and mature cells of vascular and skeletal tissue, and that oxidative damage may contribute to skeletal and vascular deficits that may emerge during extended space travel

Continuous oral contraceptives versus long-term pituitary desensitization prior to IVF/ICSI in moderate to severe endometriosis:study protocol of a non-inferiority randomized controlled trial

STUDY QUESTIONS: The primary objective is to investigate if continuous use of oral contraceptives is non-inferior compared to long-term pituitary desensitization with a GnRH agonist prior to IVF/ICSI in patients with moderate to severe endometriosis with regard to treatment efficacy. Secondary objectives concern treatment safety and cost-effectiveness. WHAT IS KNOWN ALREADY: Long-term pituitary desensitization with a GnRH agonist for 3-6 months prior to IVF/ICSI improves clinical pregnancy rates in women suffering from endometriosis. However, discussion about this treatment strategy exists because of its uncomfortable side effects. Alternatively, IVF/ICSI pre-treatment with continuously administered oral contraceptives may offer fewer side-effects and lower (in)direct costs, as well as encouraging IVF outcomes in women with endometriosis. To date, these two different IVF/ICSI pre-treatment strategies in women with endometriosis have not been directly compared. STUDY DESIGN SIZE DURATION: An open-label, parallel two-arm randomized controlled multicenter trial is planned, including patients with moderate to severe endometriosis. To demonstrate an absolute difference of 13% (delta of 10% with non-inferiority margin of 3%) with a power of 80% 137 patients per group are sufficient. Taking into account a withdrawal of patients of 10% and a cancelation rate of embryo transfer after ovarian pick up of 10% (for instance due to fertilization failure), the sample size calculation is rounded off to 165 patients per group; 330 patients in total will be included. After informed consent, eligible patients will be randomly allocated to the intervention or reference group by using web based block randomization stratified per centre. Study inclusion is expected to be complete in 3-5 years. PARTICIPANTS/MATERIALS SETTING METHODS: The research population consists of patients with moderate to severe endometriosis (ASRM III/IV) who are scheduled for their first, second or third IVF/ICSI treatment attempt. Women aged over 41 years, younger than 18 years, with a known contraindication for the use of oral contraceptives and/or GnRH agonists or with severe male factor infertility will be excluded from participation. After informed consent patients are allocated to the intervention group (one-phase oral contraceptive continuously during three subsequent months) or the reference group (three Leuprorelin 3.75 mg i.m./s.c. depot injections during three subsequent months). Tibolon 2.5 mg can be given daily as add-back therapy in the reference group. After 3 months of pre-treatment the IVF/ICSI stimulation phase will be started. The primary outcome is live birth rate after fresh embryo transfer. Secondary outcomes are cumulative live birth rate after one IVF/ICSI treatment cycle (including fresh and frozen embryo transfers up to 15 months after randomization), ongoing pregnancy rate and time to pregnancy. In addition, treatment outcome parameters, adverse events, side-effects during the first 3 months, complications, recurrence of endometriosis (complaints), quality of life, patient preferences, safety and costs effectiveness will be reported. Measurements will be performed at baseline and at 3, 6, 9, 12 and 15 months after randomization. STUDY FUNDING/COMPETING INTERESTs: All authors have no conflict of interest related to this manuscript. The department of reproductive medicine of the Amsterdam UMC location VUmc has received several research and educational grants from Guerbet, Merck and Ferring not related to the submitted work. TRIAL REGISTRATION NUMBER: The trial is registered as the COPIE trial (Continuous use of Oral contraceptives as an alternative for long-term Pituitary desensitization with a GnRH agonist prior to IVF/ICSI in Endometriosis patients) in the Dutch Trial Register (Ref. No. NTR6357, http://www.trialregister.nl). TRIAL REGISTRATION DATE: 16 March 2017. DATE OF FIRST PATIENT’S ENROLMENT: Enrollment is planned for November 2018

Learning intrinsic excitability in medium spiny neurons

We present an unsupervised, local activation-dependent learning rule for intrinsic plasticity (IP) which affects the composition of ion channel conductances for single neurons in a use-dependent way. We use a single-compartment conductance-based model for medium spiny striatal neurons in order to show the effects of parametrization of individual ion channels on the neuronal activation function. We show that parameter changes within the physiological ranges are sufficient to create an ensemble of neurons with significantly different activation functions. We emphasize that the effects of intrinsic neuronal variability on spiking behavior require a distributed mode of synaptic input and can be eliminated by strongly correlated input. We show how variability and adaptivity in ion channel conductances can be utilized to store patterns without an additional contribution by synaptic plasticity (SP). The adaptation of the spike response may result in either "positive" or "negative" pattern learning. However, read-out of stored information depends on a distributed pattern of synaptic activity to let intrinsic variability determine spike response. We briefly discuss the implications of this conditional memory on learning and addiction.Comment: 20 pages, 8 figure