Open Biomedical Engineering Journal最新文献

Background: Creating appropriately-sized, lethal isotherms during cryoablation of renal tumors is critical in order to achieve sufficiently-sized zones of cell death. To ensure adequate cell death in target treatment locations, surgeons must carefully select the type, size, location, and number of probes to be used, as well as various probe operating parameters.

Objective: The current study investigates the effects of probe type, operating pressure, and clinical method on the resulting sizes of isotherms in an in vitro gelatin model.

Method: Using a total of four cryoprobes from two manufacturers, freeze procedures were conducted in gelatin in order to compare resulting sizes of constant temperature zones (isotherms). The effects of certain procedural parameters which are clinically adjustable were studied.

Results: Test results show that the sizes of 0 °C,-20 °C and -40 °C isotherms created by similarly-sized probes from two different manufacturers were significantly different for nearly all comparisons made, and that size differences resulting from changing the operating pressure were not as prevalent. Furthermore, isotherm sizes created using a multiple freeze procedure (a ten minute freeze, followed by a five minute passive thaw, followed by another ten minute freeze) did not result in statistically-significant differences when compared to those created using a single freeze procedure in all cases.

Conclusion: These results indicate that selection of the probe manufacturer and probe size may be more important for dictating the size of kill zones during cryoablation than procedural adjustments to operating pressures or freeze times.

Background: Colonic neoplasms are quite a serious problem today. Screening methods play an important role in diagnosing the disease. Colorectal cancer screening is a complex undertaking, having various options, which require a lot of efforts both from the doctor and from the patient, including the use of sedatives and the necessity of the presence of an assistant for some procedures such as colonoscopy. This is why it is very important to find a method by which one can make a diagnosis quickly, easily, and painlessly.

Methods: The ability to identify patients with tumors of the colon using the Electrophotonic Imaging (EPI) technique, as well as using it for differential diagnosis of tumors of the colon by their morphology, size and quantity was investigated. Selection of the most significant parameters of the EPI-graphy for the separation of the control group and the group of patients with tumors of the colon was developed. 137 people were studied with the EPI camera, with ages ranging from 16 to 86 years, including 49 males and 88 females. Based on the results of the colonoscopy and histological findings all subjects were divided into 2 groups: control group of 55 people, 9 males, 46 females; and patients with tumors (benign or malignant) of the colon - 82 people; 40 males and 42 females. Then all subjects were divided into smaller groups based on morphology, size, number of tumors and localization.

Results: Based on the identified indicators decision rules to determine the patients with tumors of the colon were constructed. The specificity of the resulting function was 80.0% and sensitivity 75.6%. Decision rule was built as well with logistic regression. The specificity of the resulting function was 78.2% and sensitivity 90.0%. The accuracy of this approach was higher than using discriminant analysis.

Conclusions: The results of this study have proven the ability to identify patients with tumors of the colon using EPI technology, as well as use it for differential diagnosis of tumors of the colon by their morphology, size and quantity. EPI testing is non-invasive, takes less than five minutes, and equipment is relatively cheap and accessible in mass production. This opens up good prospects for further research for implementation as a first step of the screening process. This paper presents the pilot study developing methodological approach to the GDV data processing. That is why we tried different methods of data processing. At the same time we do not pretend to develop a diagnostic method - sample size is too small for this, and other cancer types were not studied. Further research is needed.

The response properties of individual neurons in the primary visual cortex (V1) are among the most thoroughly described in the mammalian central nervous system, but they reveal less about higher-order processes like visual perception. Neural activity is highly nonlinear and non-stationary over time, greatly complicating the relationships among the spatiotemporal characteristics of visual stimuli, local field potential (LFP) signal components, and the underlying neuronal activity patterns. We applied discrete wavelet transformation to detect new features of the LFP that may better describe the association between visual input and neural ensemble activity. The relative wavelet energy (RWE), wavelet entropy (WS), and the mean WS were computed from LFPs recorded in rat V1 during three distinct visual stimuli: low ambient light, a uniform grey computer screen, and simple pictures of common scenes. The time evolution of the RWE within the γ band (31-62.5 Hz) was the dominant component over certain periods during visual stimulation. Mean WS decreased with increasing complexity of the visual image, and the time-dependent WS alternated between periods of highly ordered and disordered population activity. In conclusion, these alternating periods of high and low WS may correspond to different aspects of visual processing, such as feature extraction and perception.

Background: The dermis is a commonly used source tissue for biologic scaffolds; all cellular and nuclear materials need to be removed to limit the inflammatory immune response by the host organism. The decellularization is critical because it must preserve the structural integrity of the extracellular matrix. This work has analyzed a decellularization procedure commonly followed for the dermal tissue that is a chemical treatment with sodium hydroxide. The goal of this work is to identify the optimal treatment length on the basis of structural properties.

Methods: Tensile tests have been performed on the native tissue and on tissues decellularized for 1-7 weeks in sodium hydroxide. The collected data have been analyzed through Tukey-Kramer test to assess if the mechanical properties (ultimate tensile stress and elastic modulus) of decellularized tissues were significantly different from the properties of the native tissue. These tests have been performed on specimens cut along two orthogonal directions (parallel and perpendicular to Langer's lines).

Results: The decellularization treatment performed with sodium hydroxide in general weakens the tissue: both the ultimate stress and the elastic modulus get lower. The structural properties along Langer lines orientation are more strongly impacted, while the structural properties orthogonal to Langer lines can be preserved with an optimal duration of the decellularization treatment that is 5-6 weeks.

Conclusion: The duration of the decellularization treatment is critical not only to reach a complete decellularization, but also to preserve the mechanical properties of the tissue; 5-6 week treatment performed with sodium hydroxide allows preserving the mechanical properties of the native tissue perpendicularly to Langer lines orientation, and minimizing the impact of the decellularization process on the mechanical properties along the Langer lines orientation.

Background: Micro-needles were proposed as one of the alternatives to deliver drugs painlessly passing through stratum corneum in recent years. In this work, a mathematical model is presented to characterize the in fusion flow of a hollow micro-needle array driven by a micro-pump.

Methods: By assuming the injection of each micro-needle undergoes a spherical expansion and diffusion, the model is able to calculate the time-varying expansion radius, and the diffusion boundary, provided that the material properties and the micro-needle system parameters are known.

Results and conclusion: The calculation results show that the expansion caused by the infusion of micro-needles stops and the flow rate drops to zero in a short time. However, the diffusion boundary is much bigger than the expansion and the infusion continues if the surrounding material is absorptive. The experimental results of jet infusion through a single needle in silicon rubber and polyacrylamide gel agree with the calculation results qualitatively.

Introduction: Modern day antiretroviral therapy allows HIV+ pregnant women to lower the likelihood of viral transmission to their infants before, during, and after birth from 20-45% to less than 5%. In developing countries, where non-facility births may outnumber facility births, infant access to safe antiretroviral medication during the critical first three days after birth is often limited. A single-dose, polyethylene pouch ("Pratt Pouch") addresses this challenge by allowing the medication to be distributed to mothers during antenatal care.

Methods: The Pratt Pouch was introduced as part of a one year clinical feasibility study in two districts in Southern Province, Zambia. Participating nurses, community health workers, and pharmacists were trained before implementation. Success in achieving improved antiretroviral medication access was assessed via pre intervention and post intervention survey responses by HIV+ mothers.

Results: Access to medication for HIV-exposed infants born outside of a health facility increased from 35% (17/51) before the introduction of the pouch to 94% (15/16) after (p<0.05). A non-significant increase in homebirth rates from 33% (pre intervention cohort) to 50% (post intervention cohort) was observed (p>0.05). Results remained below the national average homebirth rate of 52%. Users reported minimal spillage and a high level of satisfaction with the Pratt Pouch.

Conclusion: The Pratt Pouch enhances access to infant antiretroviral medication in a rural, non-facility birth setting. Wide scale implementation could have a substantial global impact on HIV transmission rates from mother to child.

Background: Reconstruction of large bone defects is a great challenge in orthopedic research. In the present study, we prepared composites of bone marrow-derived stromal cells (BMSCs) and β-tricalcium phosphate (β-TCP) with three novel aspects: proliferation of BMSCs with continuous dexamethasone treatment, cell loading under low pressure, and use of autologous plasma as the cell loading medium. The effectiveness of the resulting composite for large bone-defect reconstruction was tested in a non-human primate model, and the bone union capability of the regenerated bones was examined.

Materials and methods: Primary surgery: Bone defects (5 cm long) were created in the left femurs of nine cynomolgus monkeys with resection of the periosteum (five cases) or without resection (four cases), and porous β-TCP blocks were transplanted into the defects. Secondary surgery: Bone marrow aspirates harvested from seven of the nine monkeys were cultured with dexamethasone, and BMSCs were obtained. BMSCs were suspended in autologous plasma and introduced into a porous β-TCP block under low-pressure conditions. The BMSC/β-TCP composites were transplanted into bone defects created at the same sites as the primary surgery. Bone union evaluation: Five regenerated femurs were shortened by osteotomy surgery 8 to 15 months after transplantation of the β-TCP/BMSC composites, and bone union was evaluated radiographically.

Results: After the primary surgery and treatment with β-TCP alone, one of the five periosteum-resected monkeys and two of the four periosteum-preserved monkeys exhibited successful bone reconstruction. In contrast, five of the seven cases treated with the β-TCP/MSC composite showed successful bone regeneration. In four of the five osteotomy cases, bone union was confirmed.

Conclusion: We validated the effectiveness of a novel β-TCP/BMSC composite for large bone defect regeneration and confirmed the bone union capability of the regenerated bone.

This study was aimed to optimize the extraction process for Salvia miltiorrhiza Bunge polysaccharide using response surface methodology The results showed that four operating parameters including microwave power, microwave time and the particle size had notable effects on the polysaccharide extraction of Salvia miltiorrhiza Bunge. The effects could be ranked in decreasing order of importance as follows:. Microwave power > microwave time > the comminution degree. The optimal extraction parameters were determined as 573.83W of Microwave power and 8.4min of microwave time and 67.51mesh of the comminution degree, resulting in the yield of Salvia miltiorrhiza Bunge polysaccharide of 101.161mg / g. The established regression model describing polysaccharide extraction from as a function of the three extraction parameters was highly significant (R 2 = 0.9953). The predicted and experimental results were found to be in good agreement. Thus, the model can be applicable for the prediction of polysaccharide extraction from Salvia miltiorrhiza Bunge.

In order to observe the effects of whey protein powder on hematological indexes of players majoring in physical education in the basketball training, the authors divided the players randomly into a control group and a nutrition group. Athletes complete the 30 minutes quantitative exercise using cycle ergometer respectively before the trial and after one month trial. Then we exsanguinated immediately after exercise, extracted heparin and measured hemoglobin, red blood cell count, hematocrit and mean corpuscular volume and other hematological indices. The results showed that after taking whey protein powder, the HB, RBC, HCT of nutrition group was significantly higher that the control group. This suggests that in high-intensity training, taking whey protein powder can cause changes of HB, RBC and HCT in human body, meanwhile MCV essentially the same. So whey protein powder can improve exercise capacity, and has anti-fatigue effect.