Characterization of bacterial swarming motility: a review / 生物工程学报

Swarming motility is a typical synergistic motion, in which bacteria use flagella and Type Ⅳ Pili together to move collectively on semi-solid surfaces. Swarming motility is a hot topic of research in the field of microbiology because of its close relationship with biofilm formation, fruiting bodies formation, pathogen invasion and microbial dispersal and symbiosis. A large number of studies have been conducted on bacterial swarming motility, including changes in the expression of key proteins, changes in chemical communications between bacteria as well as mechanical changes. The expression of flagellin and the level of intracellular c-di-GMP complicatedly regulates the collective behavior of bacteria in colonies, which consequently impacts the swarming motility. The unique physical properties of swarmer cells are conducive to the expansion of the whole colony. Factors such as nutrient and water content in the surrounding growth environment of bacteria also affect the ability of bacteria to swarm to different degrees. It is challenging to construct a universal model of swarming motility based on the molecular mechanisms of swarming in the future.

Chiral mesoporous silica nano-screws as an efficient biomimetic oral drug delivery platform through multiple topological mechanisms

In the microscale, bacteria with helical body shapes have been reported to yield advantages in many bio-processes. In the human society, there are also wisdoms in knowing how to recognize and make use of helical shapes with multi-functionality. Herein, we designed atypical chiral mesoporous silica nano-screws (CMSWs) with ideal topological structures (e.g., small section area, relative rough surface, screw-like body with three-dimension chirality) and demonstrated that CMSWs displayed enhanced bio-adhesion, mucus-penetration and cellular uptake (contributed by the macropinocytosis and caveolae-mediated endocytosis pathways) abilities compared to the chiral mesoporous silica nanospheres (CMSSs) and chiral mesoporous silica nanorods (CMSRs), achieving extended retention duration in the gastrointestinal (GI) tract and superior adsorption in the blood circulation (up to 2.61- and 5.65-times in AUC). After doxorubicin (DOX) loading into CMSs, DOX@CMSWs exhibited controlled drug release manners with pH responsiveness in vitro. Orally administered DOX@CMSWs could efficiently overcome the intestinal epithelium barrier (IEB), and resulted in satisfactory oral bioavailability of DOX (up to 348%). CMSWs were also proved to exhibit good biocompatibility and unique biodegradability. These findings displayed superior ability of CMSWs in crossing IEB through multiple topological mechanisms and would provide useful information on the rational design of nano-drug delivery systems.

Exploration and insights into the cellular internalization and intracellular fate of amphiphilic polymeric nanocarriers

The beneficial or deleterious effects of nanomedicines emerge from their complex interactions with intracellular pathways and their subcellular fate. Moreover, the dynamic nature of plasma membrane accounts for the movement of these nanocarriers within the cell towards different organelles thereby not only influencing their pharmacokinetic and pharmacodynamic properties but also bioavailability, therapeutic efficacy and toxicity. Therefore, an in-depth understanding of underlying parameters controlling nanocarrier endocytosis and intracellular fate is essential. In order to direct nanoparticles towards specific sub-cellular organelles the physicochemical attributes of nanocarriers can be manipulated. These include particle size, shape and surface charge/chemistry. Restricting the particle size of nanocarriers below 200 nm contributes to internalization

Polarization and Arrangement of Epithelial Cells in the Embryonic Development of Drosophila / 医用生物力学

Objective To study the polarization and arrangement of epithelial cells in the embryonic development of drosophila. Methods A finite element model was established to simulate the development of drosophila egg, and an ABAQUS UMAT user subroutine that describes the growth of materials was developed. The developmental process of the stages 8 (S8) to the initial state of the stage 10 (S10) was simulated， and the direction of principal stress and the distribution of the in-plane maximum shear stress (MSS) in the epithelial cell layer was analyzed, in order to predict the polarization and arrangement of the epithelial cells. Results The orientation of the epithelial cells was consistent with the direction of the maximum principal stress, and the aspect ratio of cells was proportional to the magnitude of the MSS. Conclusions The polarization and arrangement of the epithelial cells are controlled by the stress state in the tissues.

Rapid Preparation of Micro-sized Gold Nanorods / 分析化学

The effects of cetyltrimethylammonium bromide ( CTAB) , ascorbic acid, NaBH4 and AgNO3 , as well as the stirring time and reaction time on the preparation of gold nanorods synthesized with seedless growth method were studied. The optimum preparation conditions were obtained in the process of growth of gold nanorods. The gold nanorods prepared under different conditions were characterized by visible absorption spectroscopy and transmission electron microscopy ( TEM ) . Under the optimum conditions such as room temperature, 0. 1 mol/L CTAB, 96 μmol/L AgNO3 , 0. 97 mmol/L ascorbic acid, 1. 5 μmol/L NaBH4 and stirring for 25 s, micro-sized gold nanorods with uniform morphology, good dispersibility, small shaft width and high aspect ratio were prepared within 6 h. The gold nanorods were expected to be applied to the detection of mercury ion in water environment.

Rapid Preparation of Micro-sized Gold Nanorods / 分析化学

The effects of cetyltrimethylammonium bromide ( CTAB) , ascorbic acid, NaBH4 and AgNO3 , as well as the stirring time and reaction time on the preparation of gold nanorods synthesized with seedless growth method were studied. The optimum preparation conditions were obtained in the process of growth of gold nanorods. The gold nanorods prepared under different conditions were characterized by visible absorption spectroscopy and transmission electron microscopy ( TEM ) . Under the optimum conditions such as room temperature, 0. 1 mol/L CTAB, 96 μmol/L AgNO3 , 0. 97 mmol/L ascorbic acid, 1. 5 μmol/L NaBH4 and stirring for 25 s, micro-sized gold nanorods with uniform morphology, good dispersibility, small shaft width and high aspect ratio were prepared within 6 h. The gold nanorods were expected to be applied to the detection of mercury ion in water environment.

Effect of aspect ratio on the uptake and toxicity of hydroxylated-multi walled carbon nanotubes in the nematode, Caenorhabditis elegans

OBJECTIVES: In this study, the effect of tube length and outer diameter (OD) size of hydroxylated-multi walled carbon nanotubes (OH-MWCNTs) on their uptake and toxicity was investigated in the nematode Caenorhabditis elegans using a functional mutant analysis. METHODS: The physicochemical properties of three different OH-MWCNTs were characterized. Uptake and toxicity were subsequently investigated on C. elegans exposed to MWCNTs with different ODs and tube lengths. RESULTS: The results of mutant analysis suggest that ingestion is the main route of MWCNTs uptake. We found that OH-MWCNTs with smaller ODs were more toxic than those with larger ODs, and OH-MWCNTs with shorter tube lengths were more toxic than longer counterparts to C. elegans. CONCLUSIONS: Overall the results suggest the aspect ratio affects the toxicity of MWCNTs in C. elegans. Further thorough study on the relationship between physicochemical properties and toxicity needs to be conducted for more comprehensive understanding of the uptake and toxicity of MWCNTs.

Effect of aspect ratio on the uptake and toxicity of hydroxylated-multi walled carbon nanotubes in the nematode, Caenorhabditis elegans

OBJECTIVES: In this study, the effect of tube length and outer diameter (OD) size of hydroxylated-multi walled carbon nanotubes (OH-MWCNTs) on their uptake and toxicity was investigated in the nematode Caenorhabditis elegans using a functional mutant analysis. METHODS: The physicochemical properties of three different OH-MWCNTs were characterized. Uptake and toxicity were subsequently investigated on C. elegans exposed to MWCNTs with different ODs and tube lengths. RESULTS: The results of mutant analysis suggest that ingestion is the main route of MWCNTs uptake. We found that OH-MWCNTs with smaller ODs were more toxic than those with larger ODs, and OH-MWCNTs with shorter tube lengths were more toxic than longer counterparts to C. elegans. CONCLUSIONS: Overall the results suggest the aspect ratio affects the toxicity of MWCNTs in C. elegans. Further thorough study on the relationship between physicochemical properties and toxicity needs to be conducted for more comprehensive understanding of the uptake and toxicity of MWCNTs.

Can We Use the Posterior Condylar Off set as a Predictive Factor for Overhang of the Implant in Total Knee Arthroplasty?

PURPOSE: We tried to demonstrate whether the posterior condylar offset (PCO, the distance from the femoral diaphysis posterior cortex to the posterior condylar margin) and ratio (PCOR, dividing PCO by the maximum antero-posterior diameter of the distal femur) could be used as predictive factors for overhang of the implants or using gender implants in total knee arthroplasty (TKA). MATERIALS AND METHODS: One hundred and one women who underwent TKA using NexGen(R) (LPS) implants, were analyzed prospectively. After distal femoral resection, the mediolateral (ML) width was measured at four points (anterior, distal anterior, distal posterior and posterior) and compared with the ML width of the implant. The aspect ratio (AR, ML/AP ratio) and anterior/distal posterior ML width (Ant/DP) were calculated. Preoperative radiographic PCO and PCOR were measured. Differences of PCO, PCOR, AR and Ant/DP according to the size were analyzed and correlations between PCO, PCOR and AR were also analyzed. The patients were classified into two groups according to the presence of overhang, and differences of each parameter were compared between the two groups. RESULTS: The size of the implant was positively correlated PCO, not significantly correlated with PCOR, and negatively correlated with AR and Ant/DP. PCO and PCOR and AR showed no correlation with each other. PCO and PCOR were not significantly different between the two groups. However, AR and Ant/DP were statistically low in the group with overhang. CONCLUSIONS: Preoperative radiographic PCO or PCOR could not be used as a predictive factor for overhang of the implants or using gender implants in TKA.

Resected femoral anthropometry for design of the femoral component of the total knee prosthesis in a Korean population / 대한해부학회지

We measured the mediolateral (ML) and anteroposterior (AP) length, height and widths of the anterior, posterior and inferior section of the resected distal femurs using three dimensional computer tomographic measurements in 200 knees from 100 cadavers. We also calculated the aspect ratio (ML/AP) and compared the measured parameters with that of six conventionally used total knee femoral prostheses. We found that the average ML (70.2+/-5.5 mm) and AP (53.9+/-3.8 mm) dimensions from our study were lower than those reported from Western populations. The aspect ratio showed a progressive decline with an increasing antero-posterior dimension. All of the compared designs showed undersizing for the mediolateral dimension distally and for the widths of the resected medial and lateral posterior femoral condyles. But some of the compared designs showed oversizing for the height of the resected medial and lateral posterior femoral condyles. This study provides guidelines for designing a suitable femoral component for total knee prostheses that fit Asian populations.

Optical Properties and Biomedical Application of Gold Nanorods / 生物化学与生物物理进展

Gold nanorods is a capsule-shaped gold nanoparticles. Gold nanorods give rise to two absorption peaks corresponding to their plasmonic modes, transverse mode and longitudinal mode, corresponding to light absorption and scattering along the short and long axis, respectively. The longitudinal surface plasmon resonance can be tuned by adjusting their aspect ratio from the visible to the NIR region and extremely sensitive to changes in the dielectric properties of the surroundings including solvents, adsorbates, and the interparticle distance of the gold nanorods. This unique optical property of gold nanorods opens up fascinating applications in biological and chemical sensors. Optical properties and biomedical application of gold nanorods are introduced, and its future research prospects are discussed.

Angiographic Characteristics of the Intracranial Saccular Aneurysms to Predict the Rupture / 대한뇌혈관외과학회지

OBJECTIVE: During the last two decades, detection of unruptured intracranial aneurysms has increased because of the improving diagnostic methods, but the management of unruptured intracranial aneurysm is still controversial. We analyzed the angiographic characteristics to compare ruptured aneurysms with unruptured aneurysms. METHODS: The patients were retrospectively selected for this study based on the availability of angiograms and a clear diagnosis of an unruptured or ruptured aneurysm. One hundred sixty nine patients with 209 aneurysms were included in the study. Sixty-one patients harbored only unruptured lesions, 85 only ruptured lesions and 27 had both ruptured and unruptured lesions. RESULTS: The mean age of all the patients was 55.3 years, and it was 53.34 years for those with ruptured aneurysms. It was found that 42.0% of the ruptured aneurysms were on the anterior communicating artery, compared with 10.3% of the unruptured aneurysms. None of the ophthalmic artery aneurysms were ruptured. The mean dome size, depth and aspect ratio of the ruptured aneurysms, except for the neck size, were significantly larger than that of the unruptured aneurysms, but the mean neck size of the ruptured and unruptured aneurysms showed no significant difference. A daughter sac was present in 7.2% of the unruptured aneurysms and in 17.0% of the ruptured aneurysms. CONCLUSION: We suggest that the morphologic features and location of aneurysms should be considered when making decisions regarding whether to treat unruptured aneurysms.

Significance of Aspect Ratio as Predictor of Intracranial Aneurysm Rupture / 대한뇌혈관외과학회지

OBJECTIVE: The size of intracranial aneurysm has been well known as a risk factor of aneurysmal rupture. The aneurysmal shape affects risk of rupture differently even though the size is similar. Aspect ratio corresponds well with morphologic variability. In this study we investigated the significance of aspect ratio as a predictor of intracranial aneurysm rupture. METHODS: The authors reviewed the retrospectively the medical records of consecutive patients with ruptured and unruptured intracranial aneurysms who underwent cerebral angiography from January 2001 to December 2005. A total of 156 patients underwent cerebral angiography and 171 aneurysms were detected. One hundred forty ruptured and 31 unruptured aneurysms were included. We measured aspect ratio which aneurysmal dome distance and neck width on angiographic images. To compare the difference of size and aspect ratio between ruptured and unrupteured aneurysms, we performed statistical analysis of aspect ratio to obtain the odds ratio(OR) for risk of rupture. RESULTS: The mean aspect ratio was 2.33+/-0.96 for ruptured aneurysms, compared with 1.71+/-0.55 for unruptured aneurysms. The difference of the aspect ratios between ruptured and unruptured groups was statistically significant (p<0.001). The odds ratio of rupture was 6.3 fold greater when the aspect ratio was larger than 2.66 compared with an aspect ratio less than 1.54. CONCLUSION: We suggest that aspect ratio is a significant independent predictor for aneurysmal rupture. The rupture risk was increased significantly when aspect ratio increased.

Aspect Ratio(dome/neck) of Ruptured and Unruptured Aneurysms in Relation to Their Sizes and Sites and Ages of Patients: Clinical Research / 대한뇌혈관외과학회지

OBJECT: This study was undertaken to assess the reliability of aspect ratio (AR: the maximum dimension of the dome/width of the neck of an aneurysm) in predicting aneurysm rupture. The authors sought to evaluate the utility of these measures for differentiating ruptured and unruptured aneurysms. METHODS: Patients were retrospectively selected for this study based on the availability of angiograms and a clear diagnosis of an unruptured or ruptured aneurysm. 106 patients with 140 aneurysms were included. 19 patients harbored only unruptured lesions, 70 patients only ruptured lesions, and 17 both ruptured and unruptured lesions. The size of the aneurysms and their ARs were determined by examining the angiographic films. Patient's age and sex, and the location of the aneurysm were also recorded. RESULTS: The ruptured aneurysms were larger and had greater ARs. The mean size of unruptured aneurysms was 4.94 mm and that of ruptured ones was 5.53 mm; the corresponding mean ARs were 1.50 and 1.96, respectively. The odds ratio for rupture rose progressively only for the AR. Only 38.3% of ruptured aneurysms had an AR less than 1.80 compared with 74.0% of unruptured lesions. The odds of rupture were 28-fold greater when the AR was larger than 2.07 compared with an AR with an AR less than or equal to 1.30. Only 9.3% of ruptured aneurysms had and AR less than 1.30 compared with 48.1% of unruptured lesions. CONCLUSION: A high AR might reasonably influence the decision to treat actively an unruptured aneurysm independent of its maximum size, so great care should be taken for patients with unruptured intracranial aneurysms with AR of more than 1.80.

Development of wing morphology in the Indian pygmy bat Pipistrellus mimus.

The growth and development of the wing parameters of the Indian pygmy bat Pipistrellus mimus was studied under natural conditions. Newborn young were marked with nontoxic coloured paint and were later marked with split rings. The wingspan and wing area showed linear growth until the age of five weeks, after which the rate of growth decreased. The observations on flight showed that at the age of 19 days the young were able to flutter their wings, at the age of 22 days they flew for a short distance and at the age of 29 days they exhibited sustained flight. The development of wing loading and aspect ratio are also presented. The decrease in wing loading as the bat grows is discussed as an advantage to sustain flight. The aspect ratio showed a high degree of scatter at early stages of life which decreased at the later period of growth. In general the development of wing morphology of P. mimus is similar to that of other vespertilionid bats.