Journal of Bioengineering & Biomedical Science

Elevated Pressure Aqueous Hemostasis is defined as the use of hydrostatic pressure via an isotonic liquid medium in a closed surgical field to control bleeding. It is an effective yet under-characterized means of achieving hemostasis; however, compromised perfusion is a potential complication. Therefore, the objective of this study was to determine the optimal range of extravascular pressure that both limits hemorrhage and allows antegrade flow. A steady-state experimental flow system was employed to simulate series arterial and venous hemodynamics, venous collapse, and arterial hemorrhage. A corresponding lumped-parameter mathematical model, calibrated to experimental data, was then used to extrapolate to conditions of hypotension, normotension, hypertension, limited venous collapse, venous hemorrhage, and simultaneous arterial and venous hemorrhages. Experiments with an elastomeric phantom vessel showed that hemorrhage from a stab incision was diminished with increasing extravascular pressure but was accompanied by decreased antegrade flow due to venous collapse. Above arterial pressure, flow ceased. Hence, a preferred pressure domain for aqueous hemostasis was defined to be greater than venous pressure to reduce bleeding and at least ten mmHg below arterial pressure to allow antegrade flow. Results from the lumped-parameter model suggest that i) a tethered vein may permit more antegrade flow for a given extravascular pressure; and ii) an elevated extravascular pressure in the presence of a venous rent may cause intravasation. A set of indices of perfusion and hemorrhage were introduced to generalize these results and suggest guidelines for clinical practice.

Significant strides have been made since 1940s for monitoring brain activities and utilizing the information for diagnosis, therapy, and control of robotic instruments including prosthetics. Monitoring brain activities with brain computer interfacing (BCI) technologies are of recent interest to due to the immense potential for various medical applications, particularly for many neurological disorder patients, and the emergence of technologies suitable for long duration BCI applications. Recent initiatives are geared towards transforming these clinic centric technologies to patient centric technologies by monitoring brain activities in practical settings. This paper briefly reviews current status of these technologies and relevant challenges. The technologies can be broadly classified into non-invasive (EEG, MEG, MRI) and invasive (Microelectrode, ECoG, MEA). Challenges to resolve include neuronal damage, neurotrophicity, usability and comfort.

A consistent presence of floating cells is a common phenomenon in cultures of human embryonic stem cells (hESCs). However, little attention has been paid to their existence. It is currently believed that unavoidable imperfections in culture conditions lead the cells to undergo senescence and apoptosis resulting in unattached cells floating in the culture medium. Inspired by recent studies on mitotic activities in human embryonic stem cell colonies, we believe the existence of floating cells is not simply the result of unfavorable growth conditions but an intrinsic phenomenon resulted from maintaining the pluripotency of hESCs under the culture conditions. We tested this hypothesis with a set of systematic experiments and discovered: 1) the ratio of floating cells to attached cells was significantly increased with culture time; 2) the number of floating cells could be manipulated. For example, we were able to reduce the number of floating cells by providing the colonies with more horizontal or vertical cultural spaces and maintaining the cells’ pluripotency. The results open a new avenue to increase the stem cell culture efficiencies by rescuing the floating cells. On the other hand, by placing a physical barrier on the top of colonies, the number of floating cells was decreased, at the same time, hESCs also showed signs of differentiation. In addition, when inducing cells to differentiate with retinoic acid, the number of floating cells no longer increased with prolonged culture time. Taken together, these results suggested that continuous cell division across the colonies is responsible for the emergence of floating cells during hESC culture. This is quite different from the bacterial colony growth where the cells in the center of colonies are quiescent. Our results indicated that continuous cell division, even at the cost of floating cells formation, is essential for human embryonic stem cell proliferation.

Stroke remains a serious medical condition resulting in significant mortality and disability. Early detection using ultrasound technology is a way forward to prevent potential strokes. It has been known that ultrasound transducer of a single crystal with a frequency of around 2 MHz used for embolus detection in the Meddle Cerebral Artery (MCA), but no specific transducer have been validated for embolus detection in Common Carotid Artery (CCA) yet. Our study aims to use carotid phantom to report the sensitivity and specificity of embolus detection of 2 MHz, and 4 MHz PW probes in continuous monitoring of the common carotid artery. Our results show validity and high sensitivity of 2 MHz and 4 MHz pulsed Doppler transducers to detect solid embolic particles up to the size of 200 μm in a phantom of the common carotid artery. 2 MHz probe was more sensitive in detection of 200 μm particles and a symmetric to MCA probe monitoring. Simultaneous monitoring of MCA and CCA with the use of Doppler ultrasound with 2 MHz probe has a potential value to identify the active embolic signal source in patients with acute stroke. The monitoring may help to prevent or predict future acute stroke events thereby preventing potentially life threatening medical condition.

Huntington aggregation inhibitory activities and transglutaminase inhibitory activities of 2APB analogues were measured. 2-APB analogues regulated the Huntington aggregation. This fact provided an example that 2-APB analogues can regulate cellular process. Diphenyl (aminoacidonate N,O) boranes, which are effective regulator of Ca2+ release and cellular process, were effective regulators of Huntington aggregation. It was also found that many of 2-APB analogues have moderate transglutaminase inhibition activities 2-Aminoethyl di(4-trifluorophenyl) borinate is a good transglutaminase regurator.

During the last years, computer vision-based diagnosis systems have been widely used in several hospitals and dermatology clinics, aiming mostly at the early detection of malignant melanoma tumor, which is among the most frequent types of skin cancer, versus other types of non-malignant cutaneous diseases. The mortality rate can be decreased by earlier detection of suspicious lesions and better prevention. The aim of this paper is to propose an interpretable classification method for skin tumors in dermoscopic images based on shape descriptors. This work presents a fuzzy rule based classifier to discriminate a melanoma. An adaptive Neuro Fuzzy inference System (ANFIS) is applied in order to discover the fuzzy rules leading to the correct classification. In the first step of the proposed work, we apply the Dullrazor technique to reduce the influence of small structures, hairs, bubbles, light reflexion. In the second step, an unsupervised approach for lesion segmentation is proposed. Iterative thresholding is applied to initialize level set automatically. In this paper, we have also treated the necessity to extract all the specific attributes used to develop a characterization methodology that enables specialists to take the best possible diagnosis. For this purpose, our proposal relies largely on visual observation of the tumor while dealing with some characteristics such as color, texture or form. The method used in this paper is called ABCD. It requires calculating 4 factors: Asymmetry (A), Border (B), Color (C) and Diversity (D). These parameters are used to construct a classification module based on ANFIS for the recognition of malignant melanoma. Finally, we compare the results of classification obtained by ANFIS with SVM (support vector machine) and artificial neural network, and discuss how these results may influence in the following steps: the feature extraction and the final lesion classification. This framework has been tested on a dermoscopic database of 320 images. Experimental results show that the proposed method is effective in improving the interpretability of the fuzzy classifier while preserving the model performances at a satisfactory level.

Berridge discovered that inositol 1,4,5-trisphophate (IP₃) was generated at the cell surface in response to cell stimulation and functioned as a second messenger to release Ca²⁺ from internal stores. Ozaki et al. succeeded in the first total synthesis of optically active IP₃ by 13 steps. He supported the signal transduction studies by supplying necessary reagents such as IP₃, other IP_x, phosphatidyl inositol, new synthetic methods and reagents. He discovered the regulators of Ca²⁺ release and consequent cellular processes.

Inhibitory activities of 74 poly-boron compounds for SOCE and IICR were measured. Activities of poly-boron compounds were compared with 2APB, mono-boron and bis-boron compounds. The IC₅₀ of best poly-boron compound 1042 was 2 μM. This value was almost same as IC₅₀ 3 μM of 2-APB. Poly (aminoethoxyboryldiphenylether) 1042 is best candidate for regulation of Ca²⁺ release and consequent cellular processes in this paper.