Measuring female intrasexual competition by the scale for intrasexual competition: a validation of the German version

Competitive behaviour amongst members of the same sex is termed intrasexual competition. The tendency to engage in such competition appears to be strongly related to stable individual characteristics such as personality traits. Additionally, recent studies have revealed transient fluctuations in competitiveness according to the female menstrual cycle. To date, no German questionnaire exists to measure intrasexual competition. Our first study aimed to translate and validate the Intrasexual Competition Scale (ICS) by Buunk and Fisher (J Evol Psychol 7:37–48, 2009) in a population of healthy Swiss females (n = 241). Our second study applied the validated German ICS in a group of healthy, regularly cycling females (n = 49) in order to examine possible associations between the menstrual cycle phase and ICS scores. The psychometric properties suggest that the German ICS is a reliable and valid tool to assess individual differences in female intrasexual competition. Furthermore, our second study demonstrated that on average, women showed higher intrasexual competition scores when tested in the late follicular phase (M = 35.77 ± SD = 12.03) compared to the mid-luteal phase (M = 30.93 ± SD = 10.20). Our studies support previous findings of an association between ICS scores and relatively stable individual characteristics such as personality traits. Furthermore, our research endorses the assumption of cycle-dependent fluctuations in intrasexual competition. Future research should clarify the precise mechanisms underlying these findings and include biomarkers such as oestrogen and testosterone.

     

Auditory function in presbycusis: peripheral vs. central changes

The hearing abilities of a group of 30 elderly (67-93 yr of age) subjects were compared with those of a group of 30 young (19-27 yr of age) normal hearing volunteers with the aim of characterizing the changes in the peripheral and central parts of the auditory system. In elderly subjects the pure-tone thresholds were typically represented by a gradually sloping curve with a significantly greater decline in men than in women at frequencies of 3 and 4 kHz. In spite of pure tone threshold elevation in the elderly, the difference limen for intensity at 1 and 3 kHz were not significantly smaller than in the young subjects. The incidence and levels of spontaneous, transient and distortion product otoacoustic emissions were low, which would suggest the involvement of outer hair cell pathology. Also, contralateral suppression was less marked in elderly than in young subjects. Speech audiometry in the elderly revealed serious difficulties in understanding speech. Deteriorated temporal resolution, as demonstrated by increased gap detection thresholds, correlated significantly with increased speech recognition thresholds. The results support the view that presbycusis represents a combination of deteriorated function of the auditory periphery with deteriorated function of the central auditory system.     

Autocrine insulin-like growth factor-II stimulation of tumor cell migration is a progression step in human hepatocarcinogenesis

The protumorigenic insulin-like growth factor (IGF)-II is highly expressed in a significant fraction of human hepatocellular carcinomas (HCC). However, a functional dissection that clarifies the contribution of IGF-II-binding receptors in tumor progression and a respective molecular characterization of IGF-II signaling has not been performed. Therefore, expression of IGF-II and its receptors IGF-receptor type I (IGF-IR) and insulin receptor (IR) was efficiently blocked using small interfering RNA (siRNA) in HCC cells. Despite functional IR-signaling, oncogenic IGF-II effects such as tumor cell viability, proliferation, and anti-apoptosis were solely transmitted by IGF-IR. Although IGF-II signaling was previously not described in the context of HCC cell migration, the IGF-II-dependent expression profile displayed a high percentage of genes involved in cell motility and adhesion. Indeed, IGF-II overexpression promoted HCC cell migration, especially in synergy with hepatocyte growth factor (HGF). The therapeutic relevance of IGF-II/IGF-IR signaling was tested in vitro and in a murine xenograft transplantation model using the IGF-IR inhibitor picropodophyllin (PPP). IGF-IR inhibition by small molecule treatment efficiently reduced IGF-II-dependent signaling and all protumorigenic properties of the IGF-II/IGF-IR pathway. CONCLUSION: In human HCC cells, IGF-IR but not IR is involved in oncogenic IGF-II signaling. Autocrine stimulation of IGF-II induces HCC motility by integration of paracrine signals for full malignant competence. Thus, activation of IGF-II/IGF-IR signaling is likely a progression switch selected by function that promotes tumor cell dissemination and aggressive tumor behavior.     

Regenerative peripheral nerve interfaces for real-time,proportional control of a Neuroprosthetic hand

Introduction

Regenerative peripheral nerve interfaces (RPNIs) are biological constructs which amplify neural signals and have shown long-term stability in rat models. Real-time control of a neuroprosthesis in rat models has not yet been demonstrated. The purpose of this study was to: a) design and validate a system for translating electromyography (EMG) signals from an RPNI in a rat model into real-time control of a neuroprosthetic hand, and; b) use the system to demonstrate RPNI proportional neuroprosthesis control.

Methods

Animals were randomly assigned to three experimental groups: (1) Control; (2) Denervated, and; (3) RPNI. In the RPNI group, the extensor digitorum longus (EDL) muscle was dissected free, denervated, transferred to the lateral thigh and neurotized with the residual end of the transected common peroneal nerve. Rats received tactile stimuli to the hind-limb via monofilaments, and electrodes were used to record EMG. Signals were filtered, rectified and integrated using a moving sample window. Processed EMG signals (iEMG) from RPNIs were validated against Control and Denervated group outputs.

Results

Voluntary reflexive rat movements produced signaling that activated the prosthesis in both the Control and RPNI groups, but produced no activation in the Denervated group. Signal-to-Noise ratio between hind-limb movement and resting iEMG was 3.55 for Controls and 3.81 for RPNIs. Both Control and RPNI groups exhibited a logarithmic iEMG increase with increased monofilament pressure, allowing graded prosthetic hand speed control (R²?=?0.758 and R²?=?0.802, respectively).

Conclusion

EMG signals were successfully acquired from RPNIs and translated into real-time neuroprosthetic control. Signal contamination from muscles adjacent to the RPNI was minimal. RPNI constructs provided reliable proportional prosthetic hand control.

     

Biomaterial characterization of off‐the‐shelf decellularized porcine pericardial tissue for use in prosthetic valvular applications

Fixed pericardial tissue is commonly used for commercially available xenograft valve implants, and has proven durability, but lacks the capability to remodel and grow. Decellularized porcine pericardial tissue has the promise to outperform fixed tissue and remodel, but the decellularization process has been shown to damage the collagen structure and reduce mechanical integrity of the tissue. Therefore, a comparison of uniaxial tensile properties was performed on decellularized, decellularized‐sterilized, fixed, and native porcine pericardial tissue versus native valve leaflet cusps. The results of non‐parametric analysis showed statistically significant differences (p < .05) between the stiffness of decellularized versus native pericardium and native cusps as well as fixed tissue, respectively; however, decellularized tissue showed large increases in elastic properties. Porosity testing of the tissues showed no statistical difference between decellularized and decell‐sterilized tissue compared with native cusps (p > .05). Scanning electron microscopy confirmed that valvular endothelial and interstitial cells colonized the decellularized pericardial surface when seeded and grown for 30 days in static culture. Collagen assays and transmission electron microscopy analysis showed limited reductions in collagen with processing; yet glycosaminoglycan assays showed great reductions in the processed pericardium relative to native cusps. Decellularized pericardium had comparatively low mechanical properties among the groups studied; yet the stiffness was comparatively similar to the native cusps and demonstrated a lack of cytotoxicity. Suture retention, accelerated wear, and hydrodynamic testing of prototype decellularized and decell‐sterilized valves showed positive functionality. Sterilized tissue could mimic valvular mechanical environment in vitro, therefore making it a viable potential candidate for off‐the‐shelf tissue‐engineered valvular applications.