Ultrasound-enhanced bioprocess. II: Dehydrogenation of hydrocortisone by Arthrobacter simplex

Dehydrogenation of hydrocortisone by agitated suspensions of free and immobilized cells of Arthrobacter simplex ATCC 6946 was investigated under controlled ultrasonic irradiation at a frequency of 20 kH(z). The microbial conversion was optimized first with respect to mechanical agitation and subsequently with respect to an additionally superimposed sonication. The optimization of ultrasound intensity and its mode of application were established at a level which maintained the structural integrity of the cells as well as their biocatalytic activity. Various regimes of ultrasound at power densities of 0.030-0.120 W/mL were applied in systems of soluble (0.4 g/L) and excess (1 g/L) hydrocortisone and only a moderate enhancement of the bioconversion by free cells was observed. This result was explained by a better ultrasound-induced dispersal of microscopic clumps of cells and self-adhering clusters of the steroids. However, a quite significant enhancement effect was obtained in bioconversion systems of soluble substrate by gel-entrapped cells. This enhancement was explained by a phonophoretic effect associated with ultrasound-facilitated diffusion of the substrates-oxygen and hydrocortisone-within the gel beads.     

Mechanisms of enhanced antiglioma efficacy of polysorbate 80‐modified paclitaxel‐loaded PLGA nanoparticles by focused ultrasound

The presence of blood‐brain barrier (BBB) greatly limits the availability of drugs and their efficacy against glioma. Focused ultrasound (FUS) can induce transient and local BBB opening for enhanced drug delivery. Here, we developed polysorbate 80‐modified paclitaxel‐loaded PLGA nanoparticles (PS‐80‐PTX‐NPs, PPNP) and examined the enhanced local delivery into the brain for glioma treatment by combining with FUS. Our result showed PPNP had good stability, fast drug release rate and significant toxicity to glioma cells. Combined with FUS, PPNP showed a stronger BBB permeation efficiency both in the in vitro and in vivo BBB models. Mechanism studies revealed the disrupted tight junction, reduced P‐glycoprotein expression and ApoE‐dependent PS‐80 permeation collectively contribute to the enhanced drug delivery, resulting in significantly stronger antitumour efficacy and longer survival time in the tumour‐bearing mice. Our study provided a new strategy to efficiently and locally deliver drugs into the brain to treat glioma.     

Front Cover: Dual‐wavelength hybrid optoacoustic‐ultrasound biomicroscopy for functional imaging of large‐scale cerebral vascular networks (J. Biophotonics 9/2018)

We present a hybrid dual‐wavelength optoacoustic and ultrasound bio‐microscope capable of rapid transcranial visualization of morphology and oxygenation status of large‐scale cerebral vascular networks. Imaging of entire cortical vasculature in mice is achieved with single capillary resolution and complemented by simultaneously acquired pulse‐echo ultrasound microscopy scans of the mouse skull. The new approach holds potential to facilitate studies into neurological and vascular abnormalities of the brain. Further details can be found in the article by Johannes Rebling, Héctor Estrada, Sven Gottschalk, et al. ( e201800057 ).

     

Effect of β-carotene,lutein and violaxanthin on structural properties of dipalmitoyl-phosphatidylcholine liposomes as studied by ultrasound absorption technique

The effect of three carotenoid pigments, -carotene, lutein, and violaxanthin, on structural properties of dipalmitoylphosphatidylcholine liposomes was studied by means of ultrasound absorption technique. It was found that the polar carotenoid-lutein enhances drastically ultrasound absorption related to energy consumption during phase transition of a lipid component. The effect of apolar -carotene was not so much evident. No differences between the sample and control were found in the case of violaxanthin presence in liposomes. The effect of a polar carotenoid is discussed in terms of the reinforcement of the lipid matrix. Physiological aspects of carotenoid action in membranes are also briefly discussed.     

Ultrasonographic and hormonal monitoring of pregnancy in the saddle back tamarin,Saguinus fuscicollis

Ultrasonography was used in six saddle back tamarin females (Saguinus fuscicollis) to diagnose pregnancy, monitor the patterns of uterine growth and embryonic/foetal development and examine the incidence loss of single embryos/foetuses. Pregnancy was reliably diagnosed 17 days after conception, 10 days earlier than by plasma progesterone measurement. The patterns of uterine and embryonic/foetal growth paralleled those reported for the common marmoset, including a delay in embryonic development. The results support the hypothesis of retardation of organogenesis in most callitrichid species. Individual embryos could be reliably identified from day 50 of pregnancy; a loss of single embryos/foetuses after this stage did not occur. All pregnancies were carried to term, resulting in five times twins and one singleton. The smaller litter size compared to the common marmoset may be due to loss of single embryos at earlier stages of pregnancy or to a lower ovulation rate.     

Ultrasound acoustic emissions from dehydrating leaves of deciduous and evergreen trees

While drying, detached leaves produced ultrasound acoustic emissions (UAE) comparable to emissions from stem and twig wood. Experiments on Ilex aquifolium L. showed that the main source of these signals was cavitation in the veins, to which conduits and fibres probably both contributed. Regions of the leaf blade with abundant mesophyll and only small veins emitted few signals. More signals were counted on the adaxial side of the midrib than on the abaxial one and on the proximal third than on the distal one, in accordance with the anatomical structure. Sound attenuation was pronounced. Eight species were compared with respect to cavitation behaviour, field water relations and pressure–volume curves, and the data showed differences in cumulative number of events and resistance of leaves to cavitation. Data were generally in good agreement with anatomical structure and habitat preferences. The number of signals per conduit counted on cross-sections was in some leaves much higher than unity, which suggests short xylem elements or an acoustic activity of cells other than conduits. There was no correlation between cavitation threshold or cumulative number of signals and the degree of sclerophylly; unexpectedly, there was a correlation between the cumulative number of signals at a water potential of -1.3 MPa and the bulk modulus of elasticity.     

关于“弱激光血管内照射疗法”的几个问题

本文从：１．关于“弱激光血管内照射疗法（ＩｎｔｒａｖａｃｕｌａｒＬｏｗ－Ｒｅａｃｔｉｏｎ－ｌｅｖｅｌＬａｓｅｒＩｒｒａｄｉａｔｉｏｎＴｈｅｒａｐｙＩＬＬＬＴ）的中、英文名称问题。２．该疗法引入我国的历史回顾。３．该疗法的临床效果与基础研究。４．该疗法与光量子疗法（ＵＢＩ）的比较。５．该疗法在我国面临的问题及展望等五个方面以较详实的材料对以Ｈｅ—Ｎｅ激光为代表的弱激光血管内照射疗法客观地进行阐述,并以笔者的研究实践及其认识为基础提出看法以期探讨,从而澄清目前国内对该疗法尚存在的某些混乱状况与模糊认识,使其作为弱激光的一种很有前途的临床疗法能走上健康发展的道路。