Optogenetic skeletal muscle-powered adaptive biological machines

Complex biological systems sense, process, and respond to their surroundings in real time. The ability of such systems to adapt their behavioral response to suit a range of dynamic environmental signals motivates the use of biological materials for other engineering applications. As a step toward forward engineering biological machines (bio-bots) capable of nonnatural functional behaviors, we created a modular light-controlled skeletal muscle-powered bioactuator that can generate up to 300 µN (0.56 kPa) of active tension force in response to a noninvasive optical stimulus. When coupled to a 3D printed flexible bio-bot skeleton, these actuators drive directional locomotion (310 µm/s or 1.3 body lengths/min) and 2D rotational steering (2°/s) in a precisely targeted and controllable manner. The muscle actuators dynamically adapt to their surroundings by adjusting performance in response to “exercise” training stimuli. This demonstration sets the stage for developing multicellular bio-integrated machines and systems for a range of applications.Understanding complex biological systems requires uncovering the mechanisms through which integrated multicellular networks accomplish sensing, internal processing, and coordinated action in response to dynamic environmental signals. Attempting to reverse engineer these mechanisms for applications in regenerative medicine has been the focus of the burgeoning field of tissue engineering (1), and seminal advances in this field have targeted nearly every organ system in the body (2). These developments, in addition to improving the state of the art in therapeutics, have furthered our understanding of the design principles governing the organizational structure and function of natural biological systems. With this as a guide, we are ideally poised to start forward engineering biological machines, or bio-bots, capable of complex controllable nonnatural functional behaviors, thereby broadening the potential applications for building with biological materials.Before we can design bio-integrated machines for a range of applications, we must first engineer modular tissue building blocks that respond to external signals with complex functional behaviors. Observing and controlling the coordinated action of such building blocks in series and parallel will help us understand the emergent behavior of natural biological systems (3, 4). Nearly all machines require actuators, modules that convert energy into motion, to produce a measurable output in response to input stimuli. Efforts to manufacture bio-integrated actuators have targeted a range of cell types (5), including flagellated bacteria (6), cardiac muscle (7–9), and skeletal muscle (10–12). We previously demonstrated a millimeter-scale soft robotic device, or bio-bot, that uses the contractile force produced by electrically paced skeletal muscle to drive locomotion across a substrate (10). This bio-bot was the first demonstration of an untethered locomotive skeletal muscle powered biological machine and set the stage for building hierarchical actuators inspired by natural systems. However, like other previous demonstrations of bio-integrated machines, the actuator was coupled to the surrounding device and did not allow for unrestricted use in a variety of design applications. A significant step forward in this field thus requires a modular bioactuator that demonstrates a variety of controllable and tunable functional behaviors in response to a noninvasive external signal.Here, we present a bioactuator that can be coupled to many different mechanical bio-bot skeletons to provide a desired contractile force output. Two major design advances enable forward engineering bio-bots capable of more complex behaviors: (i) skeletal muscle cells are transduced to express a light sensitive cation channel, using an existing protocol (these optogenetic cells demonstrated controlled contractility in response to noninvasive and spatiotemporally precise optical stimuli); and (ii) muscle actuators are redesigned as “rings” that can be readily coupled to a variety of bio-bot skeleton designs. The resulting bioactuators produced paced active tension forces approaching 300 µN per muscle ring. Implementing these rings as the power source in untethered bio-bots enabled directional locomotion at average speeds of 310 µm/s (1.3 body lengths/min) in response to optogenetic stimulation at 2 Hz. The precise spatiotemporal stimulus provided by optogenetic control also enabled the demonstration of rotation and 2D steering in a muscle-powered device, with average rotational speeds of 2°/s (120°/min). Furthermore, “exercise training” of muscle rings with dynamic optical stimuli and static mechanical stimuli during differentiation resulted in a significant increase in functional performance, with generated forces being ∼550% greater in exercised muscle rings compared with a control. These advances in design and implementation of modular muscle actuators thus set the stage for building hierarchical multicellular bio-integrated machines and systems for a range of applications. Primary applications in medicine include noninvasive drug delivery and design of dynamic multifunctional implants.     

Dynamic exercise therapy in rheumatoid arthritis: a systematic review

The aim of this systematic review was to determine the effectiveness of dynamic exercise therapy in improving joint mobility, muscle strength, aerobic capacity and daily functioning in patients with rheumatoid arthritis (RA). In addition, possible unwanted effects such as an increase in pain, disease activity and radiological progression were studied. A computer-aided search of the MEDLINE, Embase and SCISEARCH databases was performed to identify controlled trials on the effect of exercise therapy. Randomized trials were selected on the effect of dynamic exercise therapy in RA patients with an exercise programme fulfilling the following criteria: (a) intensity level such that heart rates exceeded 60% of maximal heart rate during at least 20 min; (b) exercise frequency > or = 2 a week; and (c) duration of intervention > or = 6 weeks. Two blinded reviewers independently selected eligible studies, rated the methodological quality and extracted data. Six out of 30 identified controlled trials met the inclusion criteria. Four of the six included studies fulfilled > or = 7/10 methodological criteria. Because of heterogeneity in outcome measures, data could not be pooled. The results suggest that dynamic exercise therapy is effective in increasing aerobic capacity and muscle strength. No detrimental effects on disease activity and pain were observed. The effects of dynamic exercise therapy on functional ability and radiological progression are unclear. It is concluded that dynamic exercise therapy has a positive effect on physical capacity. Research on the long-term effect of dynamic exercise therapy on radiological progression and functional ability is needed.      

胰岛ε细胞的研究进展

胰腺由外分泌组织和内分泌组织2个部分所组成,两者在机体能量平衡和营养代谢调节中发挥重要的作用．胰岛是胰腺组织中重要的内分泌功能单位,胰岛的发育和分化过程涉及一个复杂而精细的分子调控网络体系,其中包括许多转录因子的参与．经典的胰岛内分泌细胞包括α细胞、β细胞、δ细胞及PP细胞,分别产生胰升糖素、胰岛素、生长抑素及胰多肽(PP),各种胰岛细胞之间的相互调节在维持血糖稳态中具有重要的意义．表达ghrelin 的ε细胞是一种新近发现和命名的胰岛细胞类型．现着重对胰岛ε细胞的发现过程、形态学特点及生物学作用进行介绍．     

Biopharmaceutical characterization of carbamazepine immediate release tablets. In vitro-in vivo comparison

A growing concern for the biopharmaceutical characterization of pharmaceutical products increased the interest in the evaluation and identification of physicochemical properties of drugs and dosage forms that govern its biological performance. In vitro and in vivo characteristics of two carbamazepine (CAS 298-46-4) immediate release tablets were investigated and compared in order to establish level A in vitro-in vivo correlation. An in vivo study was conducted as a controlled, two-way, complete cross-over, single dose, pharmacokinetic trial in 18 subjects. The in vitro study was performed using various dissolution media in order to evaluate their potential influence on drug release and distinguish the set of experimental conditions relevant to the in vivo behavior of the investigated drug products. Beside significant differences among in vitro release profiles, the in vivo data indicated bioequivalence of the two formulations. Although a high level of correlation between in vivo and in vitro data was observed in some media, there was no single in vitro-in vivo correlation model applicable to both investigated products. The obtained results add to the existing debate on the rationale for the use of surfactants in drug release media and their in vivo relevance, emphasizing the importance of in vitro dissolution testing in addition to in vivo bioequivalence testing.     

Application of mixture experimental design in the formulation and optimization of matrix tablets containing carbomer and hydroxy-propylmethylcellulose

Using mixture experimental design, the effect of carbomer (Carbopol® 971P NF) and hydroxypropylmethylcellulose (Methocel® K100M or Methocel® K4M) combination on the release profile and on the mechanism of drug liberation from matrix tablet was investigated. The numerical optimization procedure was also applied to establish and obtain formulation with desired drug release. The amount of TP released, release rate and mechanism varied with carbomer ratio in total matrix and HPMC viscosity. Increasing carbomer fractions led to a decrease in drug release. Anomalous diffusion was found in all matrices containing carbomer, while Case — II transport was predominant for tablet based on HPMC only. The predicted and obtained profiles for optimized formulations showed similarity. Those results indicate that Simplex Lattice Mixture experimental design and numerical optimization procedure can be applied during development to obtain sustained release matrix formulation with desired release profile.     

Cross-correlation of EEG frequency bands and heart rate variability for sleep apnoea classification

Sleep apnoea is a sleep breathing disorder which causes changes in cardiac and neuronal activity and discontinuities in sleep pattern when observed via electrocardiogram (ECG) and electroencephalogram (EEG). Using both statistical analysis and Gaussian discriminative modelling approaches, this paper presents a pilot study of assessing the cross-correlation between EEG frequency bands and heart rate variability (HRV) in normal and sleep apnoea clinical patients. For the study we used EEG (delta, theta, alpha, sigma and beta) and HRV (LF_nu, HF_nu and LF/HF) features from the spectral analysis. The statistical analysis in different sleep stages highlighted that in sleep apnoea patients, the EEG delta, sigma and beta bands exhibited a strong correlation with HRV features. Then the correlation between EEG frequency bands and HRV features were examined for sleep apnoea classification using univariate and multivariate Gaussian models (UGs and MGs). The MG outperformed the UG in the classification. When EEG and HRV features were combined and modelled with MG, we achieved 64% correct classification accuracy, which is 2 or 8% improvement with respect to using only EEG or ECG features. When delta and acceleration coefficients of the EEG features were incorporated, then the overall accuracy improved to 71%.     

Single-center prospective, randomized analysis of conventional and eversion carotid endarterectomy

AIM: Several studies, comparing early and long-term results of the conventional carotid endarterectomy (CEA) and eversion carotid endarterectomy (EEA), were conducted for past 10 years. Nevertheless, it still remaining difficult to choose optimal endarterectomy technique. Choice yet mainly depends of experience of attending surgeon. The aim of this study was the comparison early and long-term results of the EEA and CEA. METHODS: Randomly, 103 patients were operated on in the eversion, and 98 patients in the conventional technique; 97 (48.3%) patients were asymptomatic and 104 (51.7%) had symptomatic lesions. All patients underwent preoperative cervical duplex scaning and neurological examination. The surgical procedure was carried out under general anesthesia. In cases with retrograde blood pressure less than 20 mmHg shunt was used; 78.6% of all CEA were finished up with 'patch' angioplasty and 21.4% by primary suture. The primary outcomes were perioperative and late mortality, perioperative and late central neurological complications, a long-term survival rate and late restenosis incidence. RESULTS: The mean follow-up was 38 months. Mortality and long-term survival rate were similar in compared groups. The perioperative central neurological complications incidence were comparable in study groups (3.9% vs 12.1% ,odds ratio 3.45, 95% confidence interval 1.1-11.1; P=0.029). The late restenosis incidence was significantly lower in eversion group (0.0% vs 6.1%). CONCLUSION: EEA has an advantage over the conventional procedure. The authors recommend CEA in cases when retrograde pressure indicated the use of the intraluminal shunting.     

Treatment of cluster headache in pregnancy and lactation

Cluster headache is a rare disorder in women, but has a serious impact on the affected woman's life, especially on family planning. Women with cluster headache who are pregnant need special support, including the expertise of an experienced headache centre, an experienced gynaecologist and possibly a teratology information centre. The patient should be seen through all stages of the pregnancy. A detailed briefing about the risks and safety of various treatment options is mandatory. In general, both the number of medications and the dosage should be kept as low as possible. Preferred treatments include oxygen, subcutaneous or intranasal sumatriptan for acute pain and verapamil and prednisone/prednisolone as preventatives. If there is a compelling reason to treat the patient with another preventative, gabapentin is the drug of choice. While breastfeeding, oxygen, sumatriptan and lidocaine for acute pain and prednisone/prednisolone, verapamil, and lithium as preventatives are the drugs of choice. As the individual pharmacokinetics differ substantially, adverse drug effects should be considered if unexplained symptoms occur in the newborn.     

Concordant in situ and in vitro data show that maternal cigarette smoking negatively regulates placental cytotrophoblast passage through the cell cycle

Maternal cigarette smoking is associated with fetal growth restriction and other pregnancy complications. To investigate possible mechanisms involving the placenta, we studied the morphology of first trimester chorionic villi from mothers who smoked. In mothers who smoked > 20 cigarettes/day, floating villi showed focal defects including an absence of cytotrophoblast stem cells and an abnormal thinning of the syncytium. Anchoring villi displayed a striking increase in the number of cytotrophoblast columns that failed to reach the uterus or degenerated in the intervillous space. Many samples showed a significant reduction in the number of anchoring villi. Also, the number of Ki67-positive cytotrophoblasts was dramatically decreased, indicating that fewer cells were in S phase of the mitotic cycle. Together, these results suggested premature depletion of the cytotrophoblast stem cell population. To test this hypothesis, we exposed anchoring villi from nonsmokers to nicotine in vitro and analyzed the effects on cytotrophoblast passage through the cell cycle. Nicotine (0.23 to 6.0 microM) negatively affected the expression of a number of cell cycle regulators/markers and BrdU incorporation, without discernable effects on apoptosis. These results link abnormal placental development secondary to maternal cigarette smoking to a substantial decrease in the mitotic potential of cytotrophoblasts.     

Patient satisfaction with doctor–patient interaction in a radiotherapy centre during the severe acute respiratory syndrome outbreak

An outpatient radiotherapy department assessed how precautions implemented during the severe acute respiratory syndrome (SARS) outbreak affected patient satisfaction with doctor–patient interaction and explored variables potentially influencing satisfaction. The information obtained would help prepare us for future infectious disease outbreaks. Outpatients seen during the outbreak completed a validated questionnaire assessing satisfaction with doctor–patient interaction. Additional items assessed included patients’ perception of SARS measures and patient demographics. Of 149 patients, 97% had heard of SARS, 92% believed SARS precautions necessary, and 54% believed contracting SARS was possible despite the precautions. Patients were satisfied with doctors wearing masks (97%), temperature checks (97%), and patients wearing masks (96%). Despite the high satisfaction levels with SARS precautions, 24% believed it had adversely affected doctor–patient interaction. With regards to doctor–patient interaction, 94% of patients were satisfied. Patients were most satisfied with the ‘information exchange’ domain (mean score 3.23 out of 4) compared to other domains (P < 0.0001, 100.00% confidence) and were less satisfied with the ‘empathy’ domain compared to other domains (P < 0.0001, 100.00% confidence). Patients were most satisfied with understanding their treatment plan (100%), doctor being honest (97%) and being understood (96%). Patients were least satisfied with information about caring for their illness (61%), that the visit could be better (59%), and the doctor showing more interest (58%). On multivariate analysis, patients who were less satisfied with SARS measures were significantly less satisfied with doctor–patient interaction (P = 0.0001). Dissatisfaction with SARS measures was associated with significant dissatisfaction for questions in all domains. Older age and non‐breast cancer patients were also less satisfied with doctor–patient interaction. Most (94%) of patients were satisfied with doctor–patient interaction, despite implementation of infectious disease prevention measures. However, patients who were dissatisfied with the SARS precautions had poorer satisfaction. In particular, physician empathy appeared to be most adversely affected. The results have relevance to any radiotherapy department preparing contingency plans in the event of infectious disease outbreaks.