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21.
B A Sanford A W de Feijter M H Wade V L Thomas 《Journal of industrial microbiology & biotechnology》1996,16(1):48-56
A new dual fluorescence technique is described which, when combined with scanning confocal laser microscopy (SCLM), can be used to visualize the components of biofilm produced byStaphylococcus epidermidis. Chemostat cultures of RP62A (a well-characterized slime-producing strain ofS. epidermidis) were used to produce mature biofilm on polyvinylcholoride (PVC) disks immobilized in a modified Robbins device using a seed and feed model system. Serial horizontal and vertical optical thin sections, as well as three-dimensional computer reconstructions, were obtained onin situ biofilm using the dual fluorescence procedure. Bacteria were visualized by green autofluorescence excited at 488 nm with an Argon laser. Cell-associated and exocellular matrix material (slime) was visualized by red fluorescence excited at 568 nm with a Krypton laser after interaction of the biofilm with Texas Red-labeled wheat germ agglutinin which is a slime-specific lectin marker. Structural analysis revealed that the cocci grew in slime-embedded cell clusters forming distinct conical-shaped microcolonies. Interspersed open channels served to connect the bulk liquid with the deepest layers of the mature, hydrated biofilm which increased overall surface area and likely facilitated the exchange of nutrients and waste products throughout the biofilm. The combined dual fluorescence technique and SCLM is potentially useful as a specific noninvasive tool for studying the effect of antimicrobial agents on the process of biofilm formation and for the characterization of the architecture ofS. epidermidis biofilm formedin vivo andin vitro on medical grade virgin or modified inert polymer surfaces. 相似文献
22.
Gerald A. Klassen David Janigan Barry Paton John Mathews Bernard Perey Allan S. Macdonald Katherine D. Barclay 《Obesity (Silver Spring, Md.)》1996,4(2):145-151
Objective: To measure red cell flux of adipose tissue in morbidly obese patients' pannus in the upright and supine position to determine factors which would render the lower pannus susceptible to ischemic necrosis. Design: A cohort study of morbidly obese subjects without ischemic necrosis. Setting: University teaching hospital. Patients: Twenty-three consecutive morbidly obese patients referred for gastroplasty. Measurements: Red cell flux, measured as RMS voltage by a laser Doppler velocimeter. An optical fiber with a tip diameter of 250μ was inserted into the upper and lower pannus and output recorded in the upright and supine positions. Other variables recorded were age, BMI, blood pressure and serum lipids. Results: Adipose tissue red cell flux demonstrates considerable spatial and temporal heterogeneity from subject to subject and in various locations in the pannus. No differences in red cell flux were detected in response to change in position. However, regression analysis demonstrated that the gradient between the upper and lower abdomen in the supine position was increasingly positive with age and in the upright position it was increasingly positive with increasing weight or BMI. Conclusions: These data suggest that red cell flux is heterogeneously distributed in the abdominal pannus and is not greatly influenced by body position. However, with increasing age and adiposity there is a gradient for decreased red cell flux to the lower portion of the pannus. This may be a factor in rendering this part of the pannus prone to ischemic fat necrosis. 相似文献
23.
本文对准分子激光PRK治疗近视眼息者503例的早期临床结果进行分析,近视范围为-2.0至-15.0D,根据术前屈光度不同分为三组,术后随访三个月.结果证实准分子激光是一种安全、有效、预测性较好的治疗近视眼方法.全部病人提高了裸眼视力,绝大部分保持了最佳矫正视力,且没有产生危及视力的并发症. 相似文献
24.
低能量He—Ne激光血管内照射治疗银屑病21例报告 总被引:1,自引:0,他引:1
21例寻常型银屑病患者,经用He-Ne激光血管内照射,功率3.5-5mw,每日照射一次,每次1小时,10次一疗程,同时伴用vitc2givq.d及鼻吸氧,二疗程间休息4-7天,经5-35次治疗,近期疗效:近期痊愈5例(23.81%),显效6例(28.57%),好转10例(47.62%),总有效率100%,复发1例(4.76%)。 相似文献
25.
F. A. Popp W. Nagl K. H. Li W. Scholz O. Weingärtner R. Wolf 《Cell biochemistry and biophysics》1984,6(1):33-52
The phenomenon of ultraweak photon emission from living systems was further investigated in order to elucidate the physical
properties of this radiation and its possible source. We obtained evidence that the light has a high degree of coherence because
of (1) its photon count statistics, (2) its spectral distribution, (3) its decay behavior after exposure to light illumination,
and (4) its transparency through optically thick materials. Moroever, DNA is apparently at least an important source, since
conformational changes induced with ethidium bromide in vivo are clearly reflected by changes of the photon emission of cells.
The physical properties of the radiation are described, taking DNA as an exciplex laser system, where a stable state can be
reached far from thermal equilibrium at threshold. 相似文献
26.
本文研究结果表明低剂量的氦氖激光可以提高绵羊精清中GOT和LDH酶的活性,并对其机制作了初步的探讨。 相似文献
27.
Relative levels of hexokinase (ATP:D-hexose 6-phosphotransferase, EC 2.7.1.1) have been determined in 16 discrete regions of adult rat brain by a quantitative immunofluorescence method. The distribution of immunofluorescence in brain sections was determined by interactive laser cytometry and related to hexokinase content by comparison with standard sections containing known amounts of the enzyme. In many of these regions, referred to here as group I regions, hexokinase content was correlated with previously reported basal rates of glucose utilization. However, several regions (group II regions) in which hexokinase content exceeded that expected from basal rates of glucose utilization were also detected. Compared with the corresponding regions from albino rat brain, higher hexokinase levels were found in the dorsal and ventral lateral geniculate (group I regions) of pigmented Norway rats, a result reflecting previously reported increased glucose utilization by these regions in pigmented rats. There was no difference in hexokinase levels in the superior colliculus, a group II structure, from albino and pigmented rats, a finding implying that a reported increase in rate of glucose utilization in the superior colliculus of pigmented rats is effected without an increase in hexokinase content. It is suggested that group II regions may be adapted to sustain increases in rates of glucose utilization that are, relative to basal rates, considerably greater than those experienced by group I regions. 相似文献
28.
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. 相似文献
29.
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. 相似文献
30.
《Bioscience, biotechnology, and biochemistry》2013,77(9):2064-2070
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. 相似文献