Cell bathing medium as a target for non thermal effect of millimeter waves

Non thermal (NT) effect of direct radiation 4 Hz-modulated 90–160 GHz of Millimeter Waves (MMW) and preliminary MMW-treated physiological solution (PS) influence were studied on snail isolated neuron, rat's brain tissue hydration and skin penetration. It was shown that the 4 Hz-modulated low intensity 90–160 GHz MMW direct radiation and MMW-treated PS leads to on single neuron shrinkage, skin and brain tissue dehydration. On the basis of obtained data it was suggested that the cell bathing aqua medium serve as a target through which the NT effect of MMW on cell hydration is realized. The MMW-induced brain tissue dehydration can considering as consequence of MMW-induced skin water structural changes leading to unknown messenger formation able to modulate the brain cell hydration. The extrasensitivity of cell hydration to low intensity of MMW radiation allow to recommend cell hydration as a cellular marker for estimation of the NT biological effect of MMW on cells and organisms.     

Dynamics of ciguatoxins from Gambierdiscus polynesiensis in the benthic herbivore Mugil cephalus: Trophic transfer implications

This study investigates ciguatoxin dynamics in mullet after controlled feeding of Gambierdiscus polynesiensis cells as a model to characterize the absorption, distribution, retention and accumulation of ciguatoxins into the second trophic level of southwestern Pacific coral reef ecosystems. Mullet (Mugil cephalus) were fed once every other day over a period of 16 days for nine toxic feedings, and ciguatoxin activity was assessed over time in blood and seven tissues using the Neuro2a assay. Within 3 h of feeding on G. polynesiensis cells, ciguatoxins attained maximal blood concentrations, indicating rapid absorption of toxins into the systemic circulation. The time course for distribution of the estimated total tissue burden of ciguatoxin closely followed the time course for blood toxin levels, indicating a rapid distribution of the ciguatoxins throughout the fish body. The large majority (95%) of the ciguatoxin ingested dose was eliminated from the examined fish tissues 24 h after a single toxic meal, indicating little retention potential for ciguatoxin. We found no evidence for ciguatoxin accumulation after nine repeated feedings spaced two days apart, indicating that mullet did not accumulate ciguatoxin. These results provide the first experimental evidence supporting the central tenet of Randall's food chain hypothesis that ciguatoxins enter the food chain by transfer from unicellular algae to herbivorous and detritus-feeding fish. We propose that a time-dependent transformation of oxopene ciguatoxins may be necessary for the concentration of ciguatoxin through higher trophic levels.     

Chronobiology of Coronary Risk Markers in Greenland Eskimos: A Comparative Study with Caucasians Residing in the Same Arctic Area

We report a comparison of fibrinolytic variables between 10 Caucasians on a predominantly European diet and 10 Greenland Eskimos on a traditional Inuit diet containing a substantial amount of fish and sea animals. We studied the diurnal variation in tissue type plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI) antigens and activities during a 24-h period. Blood samples were taken every 4 h. The variations of the sinusoidal curves were evaluated by the Friedman χ² test. t-PA and PAI-1 antigen in plasma fluctuated significantly during the 24 h (Eskimos p < 0.000007 and p < 0.0007; Caucasians p < 0.00003 and p < 0.02), with a peak in the early morning and a nadir in the afternoon. This also held true for PA1 activity (Eskimos p < 0.0008; Caucasians p < O.Ol), whereas t-PA activity showed an inverse but still significant pattern (Eskimos p < 0.006; Caucasians p < 0.0008). Amplitudes, areas underneath, and overall medians of the sinusoidal curves did not deviate between the two groups with respect to t-PA and PAL In contrast to the significant variation of t-PA and PAI, the plasma concentrations of fibrin degradation products (D-Dimer), a measure of effective fibrinolysis, remained constant during the 24 h, and the absolute differences between groups did not reach statistical significance. These findings suggest that circadian variation of fibrinolytic activators and inhibitors is a basic biologic phenomenon, which is not affected by life-style, dietary habits, or ethnic differences. Furthermore, the lack of diurnal variation in D-Dimer raises the question of whether there is a causal relationship between low morning activities of t-PA and the frequent onset of myocardial infarction at that time of day, as suggested by several authors.     

AFM-based Mapping of the Elastic Properties of Cell Walls: at Tissue,Cellular, and Subcellular Resolutions

We describe a recently developed method to measure mechanical properties of the surfaces of plant tissues using atomic force microscopy (AFM) micro/nano-indentations, for a JPK AFM. Specifically, in this protocol we measure the apparent Young’s modulus of cell walls at subcellular resolutions across regions of up to 100 µm x 100 µm in floral meristems, hypocotyls, and roots. This requires careful preparation of the sample, the correct selection of micro-indenters and indentation depths. To account for cell wall properties only, measurements are performed in highly concentrated solutions of mannitol in order to plasmolyze the cells and thus remove the contribution of cell turgor pressure.In contrast to other extant techniques, by using different indenters and indentation depths, this method allows simultaneous multiscale measurements, i.e. at subcellular resolutions and across hundreds of cells comprising a tissue. This means that it is now possible to spatially-temporally characterize the changes that take place in the mechanical properties of cell walls during development, enabling these changes to be correlated with growth and differentiation. This represents a key step to understand how coordinated microscopic cellular changes bring about macroscopic morphogenetic events.However, several limitations remain: the method can only be used on fairly small samples (around 100 µm in diameter) and only on external tissues; the method is sensitive to tissue topography; it measures only certain aspects of the tissue’s complex mechanical properties. The technique is being developed rapidly and it is likely that most of these limitations will be resolved in the near future.     

Contrast-enhancement cardiac magnetic resonance imaging beyond the scope of viability

The clinical applications of cardiovascular magnetic resonance imaging with contrast enhancement are expanding. Besides the direct visualisation of viable and non-viable myocardium, this technique is increasingly used in a variety of cardiac disorders to determine the exact aetiology, guide proper treatment, and predict outcome and prognosis. In this review, we discuss the value of cardiovascular magnetic resonance imaging with contrast enhancement in a range of cardiac disorders, in which this technique may provide insights beyond the scope of myocardial viability.     

基于相关检测的多通道近红外光组织光学测量系统

研制了一套基于相关检测技术的三波长多通道近红外光信号采集系统。采用相敏检波模块CD505R有效提高信噪比。Delphi开发的上位机程序通过串口方式与单片机通信。使用光纤传递光源及探测信号,使系统具有更大的灵活性,适用于多种组织光学特性测量方式。模型实验的结果证明该系统准确可靠,前臂阻断实验表明系统对不同深度组织血氧状况具有较好的测量能力。     

珍稀濒危植物毛柄小勾儿茶的离体培养

以珍稀濒危植物毛柄小勾儿茶（Berchemiella wilsonii（Schneid．）Nakai var．pubipetiolata H．Qian）嫩梢为外植体进行组织培养实验,结果表明：以1／2 MS＋6-BA0．5mg／L＋NAA 0．05mg／L为芽诱导培养基、MS＋6-BA0．5mg／L＋NAA 0．05mg／L为增殖培养基,可以得到大量的毛柄小勾儿茶试管苗。     

胡萝卜组织培养和高效遗传转化体系的建立

为了建立高效的胡萝卜遗传转化体系,本实验选用3个胡萝卜(Daucuscarotavar.sativa)栽培品种:‘金笋五寸’、‘Carol’和‘改良黑田七寸’,以它们的下胚轴和子叶为外植体,首先建立了高频愈伤诱导体系。在此基础上,以Carol的下胚轴和愈伤组织为受体材料,利用根癌农杆菌LBA4404介导转化质粒pBI121。经X-Gluc染色,证明GUS基因瞬间表达成功,经PCR方法鉴定,证明GUS基因已整合到胡萝卜的染色体中,从而建立了高效的胡萝卜遗传转化体系。     

霍山石斛(Dendrobidium huoshanness)的组织培养

霍山石斛(Dendrobidium huoshanness)是重要的药用植物,在组培过程中,其营养器官脱分化困难.本文研究了霍山石斛拟原球茎(PLBs)诱导的适宜条件,发现假鳞茎下段是诱导拟原球茎适宜的外植体,低浓度的NAA和CPPU的诱导效果较好,黑暗培养可缩短诱导时间,提高诱导率.