Citations

Collagen fibers in the annulus fibrosus (AF) play a significant role in maintaining the disc mechanical behavior. In healthy discs, AF fibers are concentrically arranged in a zigzag fashion. Tensile loads are transmitted to these fibers when the disc is loaded in compression. As a result, disc bulging occurs. Initiation and progression of mild cervical disc degeneration (DD) has been the subject of clinical concern [1]. The mild DD is associated with structural interruption in laminar organization of fibers in partial AF regions and incomplete length of fibers is a major form of structural interruption in AF fibers [2]. Moreover, a loss of lamellar fiber structure contributes to the progression of spinal deformity [3]. Past research have documented the biomechanical role of complete length of fibers in governing a healthy disc behavior [4]; however, there is a lack of clear understanding as to how incomplete length of fibers in different AF regions affect overall disc biomechanics and how they may play a role in initiating the propagation of DD. The focus of the current study is to investigate the disc biomechanical response due to incomplete length of fibers in outer, middle, and inner AF regions.

The age‐associated decline in growth hormone (GH) secretion may be a consequence of the reduction in the number of GH‐releasing hormone (GHRH) positive neurones. However, it remains unclear whether an alteration in the number or distribution of somatostatin (SST) neurones contributes to this change. In the present study, we characterised the role of SST in modulating the change in pulsatile GH secretion in male C57Bl/6J mice throughout puberty and into early adulthood. We assessed pulsatile GH secretion in mice at 4, 8 and 16 weeks of age. These ages correspond to early pubertal, early adulthood and adulthood, respectively. We show an elevation in peak, total and pulsatile GH secretion coinciding with periods of rapid linear growth. Using in situ hybridisation and morphometric methods, we mapped the distribution of Sst mRNA expression within the mouse brain relative to this change in pulsatile GH secretion. The results obtained show that altered pulsatile GH secretion in male mice from 4–16 weeks of age does not coincide with a significant change in the number of Sst mRNA expressing neurones or an abundance of Sst mRNA expression throughout the arcuate nucleus (ARC) and periventricular nucleus (PeV). Rather, we observed a progressive decline in Sst mRNA expressing neurones within subnuclei of the paraventricular nucleus at this time. We conclude that structural changes in Sst expression within the PeV and ARC may not reflect the observed decline in pulsatile GH secretion in mice from puberty into early adulthood.

A fully 3D, continuum mechanics based model of skeletal muscle, validated against experimental force data, can be used to computationally solve for individual muscle forces. A constitutive formulation, representing muscle as a transversely isotropic, hyperelastic, and isovolumetric material [1] has been implemented in a finite element model (FEM) of passive skeletal muscle and validated against experimental tension measurements [2]. Of further interest is an expanded formulation that will allow for the addition of muscle activation levels on the overall skeletal muscle force generation. The purpose of this study was to expand the FEA model to include muscle activation and validate it with tests of active skeletal muscle tissue at varied lengths.

The surgical goal in total knee arthroplasty (TKA) is to obtain neutral mechanical alignment within three degrees [4]. This has been considered necessary to achieve optimal function, produce balanced medial and lateral loading distributions, and prolong implant longevity [7]. Under static loading, tibial-femoral alignment angle deviations of 3° have been shown to greatly alter the distribution of pressure and load between the medial and lateral tibial plateaus [13]. However, other studies have challenged the practice that coronal tibiofemoral alignment improves implant longevity [9,10]. These studies did not show a statistical difference in the number of revision surgeries between well aligned knees and mechanical alignment outliers (varus/valgus knees). While it has been suggested that accurate alignment allows for improved joint kinematics and improved outcomes in TKA patients [6], no studies have evaluated the effect of tibial-femoral alignment on tibial plateau loading distribution during gait in the TKA population. Therefore, the purpose of this study was to assess tibial plateau loading following TKA.

Purpose To determine the rates of neurologic adverse events following Pipeline Embolic Device (PED) placement for intracranial aneurysm treatment. Methods A retrospective review of medical records was performed at 19 centres to identify consecutive intracranial aneurysms treated with the PED following regulatory approval for marketing the device in the given country. All patients in whom at least one PED was placed and in whom follow-up was available prior to IRB or ethics panel approval were enrolled. Three anatomic/size subgroups were defined, including 1) pre-PComm, internal carotid artery aneurysms 10mm or greater (“large ICA”), 2) ICA aneurysms >10mm and/or at/distal to the PComm region (“other anterior circulation”), and 3) posterior circulation aneurysms. “Primary safety events” included stroke, haemorrhage, parent artery stenosis, permanent cranial neuropathy, and spontaneous rupture of the target aneurysm. Severe safety events were defined as any event causing significant impairment of functioning causing the inability of the subject to carry out usual activities. Statistical analysis was performed using standard summary statistics; p-values comparing subgroups were computed using Pearson's chi-square test for discrete variables and analysis of variance for continuous variables. Results To date, 580 aneurysms, including 183 large ICA, 344 other anterior circulation, and 53 posterior circulation aneurysms have been treated and followed for a mean duration of 7.8 months (SD 7.3, range 0.1 - 40.8). 437 (76%) of 580 aneurysms were saccular and 80 (14%) were fusiform; 32 (5.5%) were classified as giant (<25mm diameter). 549 (93%) were unruptured. 241 (42%) were treated with multiple PEDs. Primary safety events were noted in 62 (12%) cases. Severe neurological events occurred in 35 (6.8%) cases, and occurred more frequently in posterior circulation aneurysms (7 (13%)) than in either large ICA or other anterior circulation aneurysms (15 (8.8%) and (13 (4.5%), respectively, p=.035). Major stroke occurred in 20 (3.9%) of 515 subjects (4.1%, 3.1%, and 7.5% in large ICA, other anterior circulation, and posterior circulation aneurysms, respectively, p=.31). Ipsilateral intracranial haemorrhage occurred in 12 (2.3%) subjects (3.5%, 1.7%, and 1.9% in large ICA, other anterior circulation, and posterior circulation aneurysms, respectively, p=.47). Spontaneous aneurysm rupture occurred in 3 (0.6%) aneurysms, all of which were giant, resulting in a 9% incidence of rupture in giant aneurysms. Mortality rate was 4.3% and was significantly higher for posterior circulation aneurysms (11.3%) as compared to anterior circulation aneurysms (3.5%, p=.019). Conclusions Preliminary data indicates that in approximately 7% of aneurysms treated with PED, substantial neurologic complications occurred, with rates of both severe neurologic events and mortality occurring significantly higher in the posterior as compared to the anterior circulation. Both ipsilateral haemorrhage and spontaneous aneurysm rupture were rare, with the latter event limited to giant aneurysms. Disclosures D. Kallmes: 1; C; MicroVention, Sequent, Benvenue, eV3. 2; C; General Electric, Codman, eV3. E. Boccardi: None. A. Bonafe: None. S. Cekirge: None. D. Fiorella: 2; C; Pipeline proctor, consultant, (<10K, EV3). R. Hanel: None. P. Jabbour: None. E. Levy: None. D. Lopes: 6; C; Receives compensation for training & proctoring for Pipeline devices. P. Lylyk: None. C. McDougall: None. A. Siddiqui: None. I. Szikora: None. H. Woo: None.

Background Acetazolamide induces cerebral vasodilatation and may be used to measure cerebrovascular reserve in patients with cerebral arteriopathy. While acetazolamide is known to induce transient neurologic deficits as a result of “steal phenomenon,” prolonged deficits have rarely been described. Methods Retrospective, single-centre case review from 2011 to 2012. Results We describe 3 patients ages 41, 60 and 65 years (2 women; 1 man) who developed prolonged neurological deterioration following administration of acetazolamide in the acute phase following presentation for evaluation of cerebrovascular reserve. Two patients presented with hemispheric ischaemic symptoms; one presented with headache and parietal convexity subarachnoid haemorrhage. One patient had extensive intracranial vascular disease consistent with a moyamoya-like syndrome with left middle cerebral artery (MCA) occlusion and severe left supraclinoid internal carotid artery (ICA) stenosis. Another had 50% left MCA stenosis as well as > 70% stenosis of the left ICA. She failed medical therapy, L CAS, L MCA angioplasty, and left EC-IC bypass. A third patient had occlusion of the right ICA and severe left ICA stenosis. In every case, acetazolamide challenge was carried out in the acute phase following presentation. All three patients developed significant prolonged worsening of neurologic deficits following the administration of acetazolamide (1 g). Patients received aggressive intravenous hydration. Two of the patients regained pre-acetazolamide neurological status within 18 hours. The third patient recovered several days after emergency left carotid artery stenting. Imaging studies (CT in 2 cases; MRI in 1) did not reveal interval haemorrhage or additional ischaemic changes in any case. Conclusion Administration of acetazolamide has the potential to induce decline in neurological function after administration in the acute phase and may be persistent for several hours or days. A steal phenomenon is a possible mechanism. The combination of severe extracranial and intracranial vascular disease may predispose to prolonged deficits and may be a contraindication to diagnostic use of acetazolamide. Disclosures R. Tawk: None. B. Eidelman: None. R. Hanel: None. J. Meschia: None. K. Barrett: None.

Background. Complementary and alternative medicine (CAM) and integrative medicine (IM) modalities are widely used by patients, including those with infectious diseases (ID).Methods. One thousand randomly selected ID practitioners were surveyed. The survey was divided into domains related to familiarity and recommendation, beliefs and attitudes, and use of CAM/IM modalities.Results. The response rate was 31%. ID physicians were most familiar with vitamin and mineral supplementation (83%), massage (80%), acupuncture (79%), chiropractic (77%), yoga (74%), and herbal medicine (72%). ID physicians most recommended vitamin and mineral supplementation (80%) and massage (62%). Yoga, meditation, and acupuncture were recommended by 52%, 45%, and 46%, respectively. Drug interactions, clinical research, and knowledge of CAM/IM modalities were factors that were considered a major influence. Almost 80% of respondents indicated an interest in IM versus 11% for CAM. Most respondents (75%) felt that IM modalities are useful, and more than 50% believed that they could directly affect the immune system or disease process.Conclusion. ID physicians expressed a markedly greater interest for IM versus CAM. They appear to be familiar and willing to recommend some CAM/IM modalities and see a role for these in the management of certain infectious diseases. Data regarding clinical efficacy and safety appear to be important factors.

Introduction. While patients undergoing orthotopic liver transplantation (OLT) have high cardiovascular event rates, preoperative risk stratification may not necessarily predict those susceptible patients. Troponin T (TnT) may help predict patients at risk for cardiovascular complications.Methods. Consecutive patients undergoing OLT at Mayo Clinic in Florida between 1998 and 2010 who had TnT obtained within 10 days following surgery were included. Three groups were compared based on TnT level: (1) normal (TnT≤0.01 ng/mL), (2) intermediate (TnT 0.02–0.11 ng/mL), and (3) elevated (TnT>0.11 ng/mL). Overall and cardiovascular mortality was assessed.Results. Of the 78 patients included, there was no difference in age, gender, severity of liver disease, and echocardiographic findings. Patients in the normal and intermediate TnT groups had a lower overall mortality rate (14.3% and 0%, resp.) when compared with those with elevated TnT (50%;P=0.001). Patients in the elevated TnT group had a cardiovascular mortality rate of 37.5% compared with 1.4% in the other groups combined (P<0.01). The elevated TnT group had a much higher mortality rate when compared with those in the intermediate group (P<0.0001).Conclusion. TnT may accurately help risk stratify patients in the early postoperative setting to better predict cardiovascular complications.