慢性扁桃体炎与细菌L型感染

通常认为,慢性扁桃体炎主要致病菌是金黄色葡萄球菌和乙型溶血性链球菌。通过50例慢性扁桃体炎的病原微生物培养、组织切片细菌学及电镜等研究,发现慢性扁桃体炎组织中细菌L型也相当常见,L型培养阳性率是88.5％,且组织切片L型感染率与培养阳性率基本一致(P>0.05)。电镜在扁桃体组织间质及上皮细胞、淋巴细胞等多种细胞内均见到细菌L型。提示慢性扁桃体炎与细菌L型感染关系极为密切。并认为,L型侵入组织并在宿主细胞内生长的特性,可能是慢性扁桃体炎反复发作、迁延不愈的重要原因。     

Relationship of actin organization to growth in the two forms of the dimorphic yeastCandida tropicalis

Summary Candida tropicalis is a dimorphic yeast capable of growing both as a budding yeast and as filamentous hyphae depending upon the source of the carbon used in the culture medium. The organization of F-actin during growth of the yeast form (Y-form) and the hyphal form (H-form) was visualized by rhodamine-conjugated phalloidin by using a conventional fluorescence microscope as well as a laser scanning confocal fluorescence microscope. In single cells without a bud or non-growing hyphae, actin dots were evenly distributed throughout the cytoplasm. Before the growth of the bud or hypha, the actin dots were concentrated at one site. During bud growth, actin dots were located solely in the bud. They filled the small bud and then filled the apical two-thirds of the cytoplasm of the middlesized bud. During growth of the large bud, actin dots which had filled the apical half of the cytoplasm gradually moved to the tip of the bud. In the formation of the septum, actin dots were arranged in two lines at the conjunction of the bud and the mother cell. During hyphal growth, the majority of actin dots were concentrated at the hyphal apex. A line of clustered spots or a band of actin was observed only at the site where the formation of a new septum was imminent. This spatial and temporal organization of actin in both categories of cells was demonstrated to be closely related to the growth and local deposition of new cell wall material by monitoring the mode of growth with Calcofluor staining. Treatment of both forms of cells with cytochalasin A (CA) confirmed the close relationship between actin and new cell wall deposition. CA treatment revealed lightly stained unlocalized actin which was associated with abnormal cell wall deposition as well as changes in morphology. These results suggest that actin is required for proper growth and proper deposition of cell wall material and also for maintaining the morphology of both forms of cells.Abbrevations FM fluorescence microscopy - EM electron microscopy - rh rhodamine - CA cytochalasin A - CD cytochalasin D - PBS phosphate-buffered saline - DMSO dimethylsulfoxide - GA glutaraldehyde     

Laser microirradiation of kinetochores in mitotic PtK2 cells

Irradiation of the kinetochore region of PtK₂ chromosomes by laser light of 532 nm was used to study the function of the kinetochore region in chromosome movement and to create artificial micronuclei in cells. When the sister kinetochores of a chromosome were irradiated at prometaphase, the affected chromosome detached from the spindle and exhibited no further directed movements for the duration of mitosis. The chromatids of the chromosome remained attached to one another until anaphase, at which point they separated. No poleward movement of the chromatids was observed, and at telophase they passively moved to one of the daughter cells and were enclosed in a micronucleus. The daughter cell containing the micronucleus was then isolated by micromanipulation and followed through subsequent mitoses. At the next mitosis, two chromosomes, each with two chromatids, condensed in the micronucleus. These chromosomes did not attach to the spindle and showed chromatid separation, but no poleward movements at anaphase. They were again enclosed in micronuclei at telophase. The third generation mitosis was similar to the second. Occasionally, both the irradiation-produced and naturally occurring micronuclei exhibited no chromosome condensation at mitosis. Feulgenstained monolayers of PtK₂ cells with naturally occurring micronuclei showed that some micronuclei stain positive for DNA and others do not. This finding raises questions about the fate of chromosomes in a micronucleus.     

Brugia pahangi: Feeding and nutrient uptake in vitro and in vivo

Incubation in vitro of adult Brugia pahangi in an apparatus which permitted the separate exposure of the anterior, middle, or posterior region of the worms to medium-containing radioactively labeled d-glucose, l-leucine, and adenosine has provided evidence that these materials are taken up in physiologically significant amounts by a transcuticular route. No evidence for an oral ingestion of materials has been obtained from worms in vitro, but in vivo an oral uptake of Trypan blue has been demonstrated. The ultrastructure and cytochemical staining reactions for nonspecific esterase, acid phosphatase (EC-3.1.3.2), and leucine naphthylamidase of the gut and body wall are described.     

The measurement of subnanosecond fluorescence decay of flavins using time-correlated photon counting and a mode-locked Ar ion laser.

A system is described consisting of a mode-locked Ar ion laser and time-resolved photon-counting electronics. The system is capable of measuring fluorescence lifetimes in the subnanosecond time domain. The Ar ion laser is suitable for the excitation of flavins, since the available laser wavelengths encompass the first absorption band of the yellow chromophore. Due to the high radiation density and the short pulse, both the time and wavelength resolution of the fluorescence of very weakly emitting compounds can be measured. Experiments have been described for flavin models exhibiting single and multiple modes of decay. In these examples lifetimes were determined both from deconvolved decay curves and from direct analysis of the tail of the curve, where no interference of the exciting pulse is encountered. Both determinations showed very good agreement. Due to the highly polarized laser light the decay of the emission anisotropy could be measured directly after the exciting pulse. In principle, fast rotational motions might be detected. An anisotropy measurement conducted with a flavoprotein with a noncovalently attached FAD is presented.     

叶表面角质层在贝母属植物叶鉴定中的意义

叶表面角质层在贝母属植物叶鉴定中的意义李萍，濮祖茂，蒋鑫，刘惠娟，徐国钧（中国药科大学生药学教研室；分析中心电镜室南京２１０００９）ＴｈｅｄｉａｇｎｏｓｔｉｃｖａｌｕｅｏｆｔｈｅｃｕｔｉｃｌｅｉｎｔｈｅｌｅａｖｅｓｆｒｏｍｇｅｎｕｓＦｒｉｔｉｌｌａｒ...     

Molecular Characteristics of Bovine Serum Albumin-Dextran Conjugates

Bovine serum albumin (BSA)-dextran conjugates were prepared by using the Maillard reaction; depending on the ratio of dextran to BSA used, about 0.5–1 mol of dextran could be bound to 1 mol of native BSA. SDS–PAGE patterns revealed that BSA and dextran had been covalently bonded. Structural analyses by fluorescence spectroscopy and circular dichroism indicated that the BSA surface in each conjugate was covered with dextran without any great disruption of the native conformation. The conjugates could be grouped into two fractions on the basis of the weight-average molecular mass measured: the main fraction at 1.95–2.35×10⁵ g/mol and a less-abundant fraction with aggregates greater than 1.50×10⁶ g/mol. High-performance size-exclusion chromatography in conjunction with multi-angle laser light scattering detection revealed that the BSA-dextran conjugates prepared by using the Maillard reaction had various molar masses and radii.     

Biospeckle‐characterization of hairy root cultures using laser speckle photometry

Monitoring is indispensable for the optimization and simulation of biotechnological processes. Hairy roots (hr, plant tissue cultures) are producers of valuable relevant secondary metabolites. The genetically stable cultures are characterized by a rapid filamentous growth, making monitoring difficult with standard methods. This article focuses on the application of laser speckle photometry (LSP) as an innovative, non‐invasive method to characterize Beta vulgaris (hr). LSP is based on the analysis of time‐resolved interference patterns. Speckle interference patterns of a biological object, known as biospeckles, are characterized by a dynamic behavior that is induced by physical and biological phenomena related to the object. Speckle contrast, a means of measuring the dynamic behavior of biospeckles, was used to assess the biospeckle activity. The biospeckle activity corresponds to processes modifying the object and correlates with the biomass growth. Furthermore, the stage of the cultures’ physiological development was assessed by speckle contrast due to the differentiation between active and low active behavior. This method is a new means of monitoring and evaluating the biomass growth of filamentous cultures in real time. As a potential tool to characterize hairy roots, LSP is non‐invasive, time‐saving, can be used online and stands out for its simple, low‐cost setup.     

Femtosecond Laser‐Etched MXene Microsupercapacitors with Double‐Side Configuration via Arbitrary On‐ and Through‐Substrate Connections

The capacitance of microsupercapacitors (MSCs) can double if both sides of substrates are used to construct MSCs. Nevertheless, achieving electric connections of MSCs through substrates is a challenge due to the difficulty in precisely positioning each MSC couple that has two of the same MSCs units on two sides. In this work, taking advantage of the synchronous etching on both sides of transparent polyethylene terephthalate substrates by femtosecond laser pulses, a double‐sided configuration is attained with high precision in the alignment of back‐to‐back MSC couples and versatile double‐side MSCs are realized via arbitrary on‐ and through‐substrate connections of MXene MSC units. The MXene double‐side MSC fabricated by the series connection of 12 spiral pattern MXene MSC units with interdigital electrodes of 10 μm width interspace can output a large working voltage of 7.2 V. Additionally, femtosecond laser etching brings the transformation of MXene into titania near‐etched edges with a lateral distance less than 1 µm. Such a small laser‐affected area has little influence on the capacitive performance, which is one of advantages for femtosecond laser over conventional lasers. This research is valuable for one‐step manufacturing of highly integrated MSCs in the field of miniaturized energy storage systems.     

超连续谱激光可见谱段致人眼眩目效应研究

本文采用超连续谱激光光源滤除其红外部分仅输出可见谱段部分,在不超过国家安全标准允许的最大辐照量条件下,以正入射方式照射人眼后,记录并分析在明、暗适应条件下中心极限视力恢复时间、中心近极限视力恢复时间和视觉后像持续时间,明确超连续谱激光可见谱段对人眼的眩目效果。明适应下激光照射0.1 s导致人眼中心极限视力恢复时间为31~119 s,中心近极限视力恢复时间为19~76 s;暗适应下激光照射0.1 s导致人眼中心极限视力恢复时间为26~223 s,中心近极限视力恢复时间为13~123 s;明、暗适应下导致人眼眩目效应的最小功率密度值分别为0.055 mW/cm^2和0.005 mW/cm^2。结果表明,超连续谱激光可见谱段对人眼有良好的眩目效果,可导致数十秒至数百秒的中心视力下降,随着照射功率密度增高,眩目效应增强,显示出较好的量效关系,且相同功率密度时暗适应下人眼的眩目效果优于明适应。该研究探究了明、暗适应条件下超连续谱激光对人眼眩目效应,明确了超连续谱激光与人眼眩目的量效关系。