In Vivo Evaluation of Mg-5%Zn-2%Nd Alloy as an Innovative Biodegradable Implant Material.

Mg-based alloys have been considered as potential structural materials for biodegradable implants in orthopedic and cardiovascular applications, particularly when combined with other biocompatible alloying elements. However, the performances of Mg-based alloys in in vitro conditions do not accurately reflect their behavior in an in vivo environment. As such, the present study aimed at evaluating the in vivo behavior of a novel Mg-5Zn-2Nd-0.13Y-0.35Zr alloy designated as ZE52 alloy. In vivo assessment was carried out using cylindrical disks implanted into the sub-cutaneous layer of the skin at the back midline of male Wistar rats for up to 11 weeks. Post-implantation responses evaluated included well-being behavior, blood biochemical tests and histology. The corrosion rate of the implants, expressed in terms of hydrogen gas formation, was evaluated by radiographic assessment and CT examination. Results of the well-being behavioral and blood biochemical tests indicated that the in vivo behavior of ZE52 alloy implants was similar to that of inert Ti-6Al-4V alloy implants introduced into a control group. Moreover, histological analysis did not reveal any severe inflammation, as compared to the reference alloy. However, significant sub-cutaneous gas cavities were observed, indicative of the accelerated degradation of the ZE52 alloy implants. The accelerated degradation was also manifested by the formation of alloy debris that was encapsulated within the gas cavities. Post-implantation gas bubble puncturing resulted in the complete degradation of the Mg-based implants, indicating that the inert nature of the gas prevented accelerated degradation of the alloy before it was naturally absorbed by the body.

Correction to: In Vivo Evaluation of Mg-5%Zn-2%Nd Alloy as an Innovative Biodegradable Implant Material.

The article In Vivo Evaluation of Mg-5%Zn-2%Nd Alloy as an Innovative Biodegradable Implant Materialwritten by Elkaiam et al. was originally published electronically on the publisher's internet portal (currently SpringerLink) on September 17, 2019 with open access. With the author(s)' decision to step back from Open Choice, the copyright of the article changed on October 3, 2019 to Biomedical Engineering Society 2019 and the article is forthwith distributed under the terms of copyright.

In vivo behavior of biodegradable Mg-Nd-Y-Zr-Ca alloy.

The aim of the this study is to evaluate the in vivo behavior of Mg-1.5%Nd-0.5%Y-0.5%Zr implants with and without 0.4%Ca in comparison with inert Ti-6Al-4V reference implants. This was carried out by implanting cylindrical disks at the back midline of Wister male rats within the subcutaneous layer of the skin for up to 12 weeks. The degradation of magnesium-based implants in terms of hydrogen gas bubble formation was evaluated by radiography assessment; corrosion rate was analyzed by visual examination and weight loss measurements. The physiological response of the rats post-implantation was obtained by evaluating their wellbeing behavior and blood biochemical analysis including serum Mg, blood urea nitrogen, and serum creatinine. In addition, histological analyses of the soft tissue around the implants were carried out to assess local lesions relating to the implants such as inflammation, tissue necrosis, granulation, mineralization, and tumor development. The results obtained clearly indicate that apart from the normal degradation characteristics and subsequent formation of hydrogen gas bubbles, the in vivo behavior of Mg implants was adequate and comparable to that of Ti-6Al-4V reference alloy. In addition, it was evident that the corrosion degradation of the magnesium alloys was strongly related to the location of the implant within the animal's body. The addition of 0.4%Ca improves the biodegradation corrosion resistance of the tested magnesium implants.

Churg-Strauss syndrome: a rare presentation with otological and pericardial manifestations: case report and review of the literature.

Churg-Strauss syndrome (CSS) is a rare multisystem autoimmune disease characterized by diffuse eosinophilic infiltration and necrotizing vasculitis. There are typical manifestations of longstanding rhinosinusitis and polyposis but otological manifestations are rare and characterized by dense aural discharge, granulomatous eosinophilic infiltrate in the mastoid and middle ear with conductive hearing loss, and progressive sensory neural hearing loss--all of which are not responsive to conventional treatment. We describe the case of a 59-year-old man with a rare presentation of CSS that included chronic bilateral otitis media with hearing loss and life-threatening pericardial tamponade. Treatment with pericardiocentesis, prednisone and cyclophosphamide was beneficial and resulted in an improvement of the pericardial and otological manifestations. Early recognition and treatment of otological involvement in CSS is extremely important because of the dramatic response to corticosteroids which may prevent progression of hearing loss.

Anisocoria and middle cerebral artery saccular (berry) aneurysm in a rhesus macaque (Macaca mulatta).

A 27-year-old female rhesus macaque (Macaca mulatta) developed anisocoria. The left pupil was dilated and unresponsive to light. The macaque was euthanized because of unrelated reasons and the body was submitted for necropsy. On gross examination, a berry aneurysm of the right middle cerebral artery causing marked compression of the right optic tract was found. Arteriosclerotic changes were observed microscopically in the right middle cerebral and in the internal carotid arteries. The left iris was markedly degenerated, with atrophy of the constrictor muscle. Compression of the right optic tract may cause homonimus hemianopsia. A dilated and unresponsive left pupil indicated a lesion in the ipsilateral parasympathetic efferent pathway. In the absence of appreciable lesions of the left oculomotor nerve, the most likely cause of mydriasis was the iridic lesion. Intracranial aneurysms are common in humans (2 to 5%), but not in other species. Only about 10% of unruptured aneurysms are associated with neurologic deficits related to mechanical compression, such as visual deficits or anisocoria. Meticulous investigation of the ocular vascular and neural pathways led us to conclude that the anisocoria was unrelated to the aneurysm. To our knowledge, this report represents the first documented case of a naturally occurring intracranial aneurysm in nonhuman primates.

Effects of dynamic Stark shifts on two-photon side-mode instabilities.

We have extended our two-photon two-level instability model to include the effects of level Stark shifts and find that the shifts tend to expand the regions of side-mode gain that allow single-wavelength and multiwavelength instabilities to occur. In addition, we find that the instabilities are strongly affected by conjugate scattering off the pump-induced two-photon coherence.

The facultative photoperiodic response in the reproductive development of Amaranthus retroflexus L.: Changes in the dose response during ontogeny.

The first inductive (short-day; SD) cycle advanced the initiation of reproductive development, while additional SD cycles progressively reduced the lag phase between the start of induction and initiation. The sensitivity to SD increased during ontogeny in long-days (LD) until even the requirement for the first SD cycle disappeared at the onset of "autonomous" flowering. In photo-induced plants, the postinitiation rate of elongation of the apex was accelerated as the SD dose was increased, but was progressively slower as the start of induction was delayed closer to autonomous flowering, approaching asymptotically the rate of non-induced controls. The inflorescences were branched in plants growing continuously in LD and unbranched in those growing continously in SD. The subsequent branching of the inflorescence could be repressed by SD at any time prior to autonomous flowering, and the degree of repression increased with the induction dose. After the initial SD cycle, 1-2 additional SD could induce the loss of apical dominance, causing excessive elongation and leaf production in the subjacent branches. Further increase in the SD dose inhibited this elongation by accelerating the transformation of the apices of these branches to the reproductive state.