Improving the accuracy of analytical relationships for mechanical properties of permeable metamaterials

Permeable porous implants must satisfy several physical and biological requirements in order to be promising materials for orthopaedic application: they should have the proper levels of stiffness, permeability, and fatigue resistance approximately matching the corresponding levels in bone tissues. This can be achieved using designer materials, which exhibit exotic properties, commonly known as metamaterials. In recent years, several experimental, numerical, and analytical studies have been carried out on the influence of unit cell micro-architecture on the mechanical and physical properties of metamaterials. Even though experimental and numerical approaches can study and predict the behaviour of different micro-structures effectively, they lack the ease and quickness provided by analytical relationships in predicting the answer. Although it is well known that Timoshenko beam theory is much more accurate in predicting the deformation of a beam (and as a result lattice structures), many of the already-existing relationships in the literature have been derived based on Euler–Bernoulli beam theory. The question that arises here is whether or not there exists a convenient way to convert the already-existing analytical relationships based on Euler–Bernoulli theory to relationships based on Timoshenko beam theory without the need to rewrite all the derivations from the start point. In this paper, this question is addressed and answered, and a handy and easy-to-use approach is presented. This technique is applied to six unit cell types (body-centred cubic (BCC), hexagonal packing, rhombicuboctahedron, diamond, truncated cube, and truncated octahedron) for which Euler–Bernoulli analytical relationships already exist in the literature while Timoshenko theory-based relationships could not be found. The results of this study demonstrated that converting analytical relationships based on Euler–Bernoulli to equivalent Timoshenko ones can decrease the difference between the analytical and numerical values for one order of magnitude, which is a significant improvement in accuracy of the analytical formulas. The methodology presented in this study is not only beneficial for improving the already-existing analytical relationships, but it also facilitates derivation of accurate analytical relationships for other, yet unexplored, unit cell types

Systematic review of available guidelines on fertility preservation of young patients with breast cancer

Background: Since the survival rate of breast cancer patients has improved, harmful effects of new treatment modalities on fertility of the young breast cancer patients has become a focus of attention. This study aimed to systematically review and critically appraise all available guidelines for fertility preservation in young breast cancer patients. Materials and Methods: Major citation databases were searched for treatment guidelines. Experts from relevant disciplines appraised the available guidelines. The AGREE II Instrument that includes 23 criteria in seven domains (scope and purpose of the guidelines, stakeholder involvement, rigor of development, clarity, applicability, editorial independence, and overall quality) was used to apprise and score the guidelines. Results: The search strategy retrieved 2,606 citations; 72 were considered for full-text screening and seven guidelines were included in the study. There was variability in the scores assigned to different domains among the guidelines. ASCO (2013), with an overall score of 68.0, had the highest score, and St Gallen, with an overall score of 24.7, had the lowest scores among the guidelines. Conclusions: With the promising survival rate among breast cancer patients, more attention should be given to include specific fertility preservation recommendations for young breast cancer patients

Effects of Injection of Carbon Nanotubes on EEG and Results of a Behavioral Test in Rats

We examined the biocompatibility of carbon nanotubes (CNTs) injected i.p. into rats (1 mg/kg body mass) by recording EEG from the frontal and occipital cortex and performing the water maze router test before and after such injection. For EEG, the energy and average power spectral density of wavelet coefficients in the β, α, and θ bands were considered the features. In the water maze router experiment, the distance, time, and speed of rats were investigated as behavioral factors. Comparison of EEG signals before and after injection showed that introduction of CNTs exerted no significant effect on electrophysiological brain indices. A comparison of behavioral factors before and after injection, however, showed that injections of CNTs increased the pacing distance and time to find the desired platform and decreased somewhat the speed in the water maze router experiment. A possible reason of this phenomenon is the possible influence of CNTs on ion fluxes in brain neurons.Ми досліджували біосумісність вуглецевих нанотрубок (ВНТ), ін’єкованих щурам (1 мг/кг маси тіла, внутрішньоочеревинно), відводячи ЕЕГ та застосовуючи поведінковий тест із водним лабіринтом перед такою ін’єкцією та після неї. Параметрами ЕЕГ вважали енергію та усереднені щільності спектральної потужності вейвлет-коефіцієнтів для бета-, тета- та альфа-ритмів. В експерименті з водним лабіринтом поведінковими факторами були відстань, час та швидкість руху щурів у пошуках цільової платформи. Порівняння сигналів ЕЕГ перед ін’єкцією ВНТ та після неї показало, що введення нанотрубок істотно не впливало на електрофізіологічні показники мозку. Порівняння ж поведінкових показників перед ін’єкцією та після неї, проте, засвідчило, що введення ВНТ викликало вірогідне збільшення шляху до платформи і тривалості її пошуків, а також деяке зменшення швидкості пересування у водному лабіринті. Можливою причиною такого феномену є вплив ВНТ на іонні токи в нейронах мозку

Role of L- and T-Type Calcium Channels in Regulation of Absence Seizures in WAG/Rij Rats

In chronic experiments on five groups of WAG/Rij rats (a genetic model of absence epilepsy; six animals in each group), we recorded EEG activity from the S1po cortical area through implanted electrodes and subjected the cortex to the action of four agents affecting L- and T-type calcium channels (injections through an implanted cannula). A blocker of L-type channels, verapamil hydrochloride, an agonist of these channels, Bay K8644, an antagonist of T-type calcium channels, L-ascorbate, and an agonist of the latter channels, PMA, were used. The parameters of 7- to 10-Hz spike-wave discharges, SWDs, spontaneously generated in the cortex of this rat strain (frequency of SWDs, mean duration of the latter, and their number) were measured within the baseline interval (before injections) and within three subsequent 20-min-long post-injection intervals. Normal saline was injected in the control group. There were no significant differences in the mean peak frequency in SWDs between all examined groups (P > 0.05 in all cases). Verapamil significantly (by more than 40%; P < 0.05) decreased the mean SWD duration throughout the entire period of post-injection observation. The dynamics of the Bay K8644 effects were rather similar, but the intensity of SWD duration changes was somewhat smaller. Both the above agents in the doses used dramatically decreased the number (frequency of appearance) of SWDs within the observation period. L-ascorbate also suppressed SWD generation. The duration of these phenomena decreased mildly, while their number dropped dramatically. In the PMA group, the number of SWDs increased significantly (by 50%, P < 0.05) within the first 20-min-long interval, but this was not observed within subsequent intervals. These findings confirm that blocking or activating of L- and T-type Ca2+ channels in the S1po area (cortical focus area) can significantly control generation of SWDs during absence seizures. Possible mechanisms underlying actions of the tested agents are discussed.У хронічних експериментах на п’яти групах щурів лінії WAG/Rij (генетична модель абсанс-епілепсії; шість тварин у кожній групі) ми відводили ЕЕГ-активність від кортикальної зони S1po через імплантовані електроди і піддавали кору дії чотирьох агентів, що впливають на кальцієві канали L- та T-типів (ін’єкції через імплантовану канюлю). Використовували блокатор кальцієвих каналів L-типу верапамілу гідрохлорид, агоніст цих каналів Bay K8644, антагоніст кальцієвих каналів T-типу L-аскорбат та агоніст останніх каналів PMA. Вимірювали параметри розрядів пік-хвиля (РПХ, частота 7–10 Гц), котрі спонтанно генеруються у корі головного мозку щурів указаної лінії (частоту в межах РПХ, середню тривалість останніх та їх кількість) протягом інтервалу порівняння (перед ін’єкціями) та трьох послідовних 20-хвилинних інтервалів після ін’єкцій. Щурам контрольної групи ін’єкували фізіологічний розчин. Істотних різниць між величинами частоти в межах РПХ у всіх досліджених групах не спостерігалося (P > 0.05 у всіх випадках). Верапаміл істотно (більш ніж на 40 %; P < 0.05) зменшував середню тривалість РПХ протягом усього періоду спостереження після ін’єкцій. Динаміка ефектів Bay K8644 була вельми подібною, але інтенсивність скорочення тривалості РПХ – дещо меншою. Обидва вказані агенти у використаних дозах зумовлювали драматичне зменшення кількості (тобто частоти виникнення) РПХ протягом усього періоду спостереження. L-аскорбат також істотно пригнічував генерацію РПХ. Тривалість цих феноменів зменшувалася помірно, а їх кількість скорочувалася дуже сильно. У групі РМА кількість РПХ протягом першого 20-хвилинного інтервалу спостереження істотно зростала (на 50 % , P < 0.05), але цього не спостерігалося в межах наступних інтервалів. Наші результати підтверджують, що блокування або активація кальцієвих каналів L- та T-типів у фокальній кортикальній зоні S1po здатні істотно контролювати генерацію РПХ під час прояву абсансних судом. Обговорюються можливі механізми дії тестованих агентів

Enhancement of CD8 T-cell function through modifying surface glycoproteins in young and old mice

Previous work from our laboratory has shown that modifying cell surface glycosylation with either a Clostridium perfringens -derived sialidase (CP-Siase), or an O-linked glycoprotein endopeptidase (OSGE) can enhance the function of CD4 T cells from both young and old mice at multiple levels. Here we have re-assessed the effect of age on CD8 T-cell function, and examined the outcome of enzymatic treatment with CP-Siase and OSGE on its different aspects. Pre-treatment of CD8 T cells with either CP-Siase or OSGE led to a significant increase in anti-CD3-mediated Ca 2+ response in both young and old mice. Pre-treated CD8 T cells from both age groups also displayed a significant increase in activation-induced CD69 and CD25 expression, and produced significantly higher amounts of interleukin-2 and interferon-γ in comparison to their untreated counterparts. Furthermore, pretreatment with either enzyme enhanced granzyme B expression in CD8 T cells, and increased their cytolytic activity in vitro . These data support the notion that glycosylated surface proteins hinder CD8 T-cell activation and function in both young and old mice, and raise the possibility of significantly improving CD8 T cell function in older individuals through enzymatic alteration of surface glycoproteins.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75199/1/j.1365-2567.2006.02420.x.pd

Interleukin‐22 and CD160 play additive roles in the host mucosal response to Clostridium difficile infection in mice

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110834/1/imm12414.pd

Management of spine trauma in COVID-19 pandemic: A preliminary report

Background: COVID-19 was first identified in Iran in February 2020 and since then it spread rapidly through all over the country and soon after that it was reported as a pandemic. The current study presents a preliminary report of spine trauma management during COVID-19 pandemic. Methods: A cross sectional study was designed to evaluate patients admitted for vertebral fractures with diagnosis of COVID-19 infection on February and March 2020. Analysis was made based on clinical and laboratory data along with the imaging findings from chest HRCT. Results: Seven patients with spine trauma including five males and two females ranging from 14 to 59 years were diagnosed for COVID-19 infection through CT-scan findings. Except one, all other patients were asymptomatic for COVID-19 at the time of admission. In three cases the COVID diagnosis was made the day after arrival and in others after 10, 14 and 35 days. Five patients were treated surgically among whom four were admitted to ICU soon after the surgery. The mean ICU stay for operated patients were eight days and the mean hospital stay was 22.6 days. Conclusion: Proper diagnosis of COVID-19 is the keystone to protect both patients and health care providers. During the pandemic all admitted patients should be screened for COVID-19 infection. Unnecessary procedures for spine trauma patients should be avoided in order to reduce complications related to surgery and to preserve ICU beds. © 2020 BY THE ARCHIVES OF BONE AND JOINT SURGERY

Arene C−H Bond Activation and Arene Oxidative Coupling by Cationic Palladium(II) Complexes

N,N‘-Diaryl-α-diimine-ligated Pd(II) dimethyl complexes (^(tBu)2^(Ar)DAB^(Me))PdMe_2 and {(CF_3)_2^(Ar)DAB^(Me)}PdMe_2 {^(tBu)2^(Ar)DAB^(Me): ArNC═(CH_3)−C(CH_3═NAr, Ar=3,5-di-tert-butylphenyl; (CF_3)_2^(Ar)DAB^(Me):Ar = 3,5-bis(trifluoromethyl)phenyl} undergo protonolysis with HBF_4(aq) in trifluoroethanol (TFE) to form cationic complexes [(α-diimine)Pd(CH_3)(H_2O)][BF_4]. The cations activate benzene C−H bonds at room temperature. Kinetic analyses reveal trends similar to those observed for the analogous platinum complexes:  the C−H activation step is rate-determining (KIE = 4.1 ± 0.5) and is inhibited by H_2O. The kinetic data are consistent with a mechanism in which benzene substitution proceeds by a solvent- (TFE-) assisted associative pathway. Following benzene C−H activation under 1 atm O_2, the products of the reaction are biphenyl and a dimeric μ-hydroxide complex, [(α-diimine)Pd(OH)]_2[BF_4]_2. The Pd(0) formed in the reaction is reoxidized by O_2 to the dimeric μ-hydroxide complex after the oxidative C−C bond formation. The regioselectivity of arene coupling was investigated with toluene and α,α,α-trifluorotoluene as substrates

Effect of Different Factors on Proliferation of Antler Cells, Cultured In Vitro

Antlers as a potential model for bone growth and development have become an object of rising interest. To elucidate processes explaining how antler growth is regulated, in vitro cultures have been established. However, until now, there has been no standard method to cultivate antler cells and in vitro results are often opposite to those reported in vivo. In addition, many factors which are often not taken into account under in vitro conditions may play an important role in the development of antler cells. In this study we investigated the effects of the antler growth stage, the male individuality, passaged versus primary cultures and the effect of foetal calf serum concentrations on proliferative potential of mixed antler cell cultures in vitro, derived from regenerating antlers of red deer males (Cervus elaphus). The proliferation potential of antler cells was measured by incorporation of 3H thymidine. Our results demonstrate that there is no significant effect of the antler growth stage, whereas male individuality and all other examined factors significantly affected antler cell proliferation. Furthermore, our results suggest that primary cultures may better represent in vivo conditions and processes occurring in regenerating antlers. In conclusion, before all main factors affecting antler cell proliferation in vitro will be satisfactorily investigated, results of in vitro studies focused on hormonal regulation of antler growth should be taken with extreme caution