Laser induced autofluorescence studies of animal skin used in modeling of human cutaneous tissue spectroscopic measurements

BACKGROUND/PURPOSE: Laser-induced autofluorescence spectroscopy provides excellent possibilities for medical diagnostics of different tissue pathologies including cancer. However, to create the whole picture of pathological changes, investigators collect spectral information from patients in vivo or they study different tumor models to obtain objective information for fluorescent properties of every kind of healthy and diseased tissue. Therefore, it is very important to find the most appropriate, and close to the human skin, animal samples from the fluorescence point of view, which will allow the extrapolation of the animal data to human spectroscopic diagnostics. METHODS: In the present work, we examined the autofluorescence properties of different animal skin tissues, which are considered as the most common skin models. A nitrogen laser was used as an excitation source. Samples of healthy mouse, chicken and pig skin in vivo and/or ex vivo were studied and were compared with results obtained from investigations of healthy human skin in vivo. RESULTS AND CONCLUSION: Specific features of the recorded spectra are discussed and the possible origin of the obtained fluorescence signals is proposed. Quantitative evaluation of data extrapolation for each skin type is also depicted.     

Fat and water separation in balanced steady-state free precession using the Dixon method.

In this work the feasibility of separating fat and water signals using the balanced steady-state free precession (SSFP) technique is demonstrated. The technique is based on the observation (Scheffler and Hennig, Magnetic Resonance in Medicine 2003;49:395-397) that at the nominal values of TE = TR/2 in SSFP imaging, phase coherence can be achieved at essentially only two orientations (0 degrees and 180 degrees ) relative to the RF pulses in the rotating frame, under the assumption of TR < T2, and independently of the SSFP angle. This property allows in-phase and out-of-phase SSFP images to be obtained by proper choices of the center frequency offset, and thus allows the Dixon subtraction method to be utilized for effective fat-water separation. The TR and frequency offset for optimal fat-water separation are derived from theories. Experimental results from healthy subjects, using a 3.0 Tesla system, show that nearly complete fat suppression can be accomplished.     

连续性静脉-静脉血液滤过联合机械通气治疗ARDS的临床观察

目的　观察连续性静脉 -静脉血液滤过 (CVVH)联合机械通气治疗ARDS患者的临床疗效。方法　选择入住ICU符合ARDS诊断标准的患者 4 0例 ,随机分为 2组 :A组 2 1例 ,采用常规治疗 +机械通气 ;B组 1 9例 ,采用常规治疗 +机械通气 +CVVH。分别观察 2组患者在使用呼吸机时间、氧合指数、吸入氧浓度、动脉血氧分压、PEEP水平、心率、血压及病死率等方面的差别。结果　A、B两组患者在病因、年龄、性别、APACHEⅡ评分及平均脏器功能障碍数等方面相似 ,B组患者加用CVVH后 ,各项指标经统计学处理显示 :病死率 ,B组与A组比较 ,差异有显著性意义 (P <0 0 5 ) :其他指标与A组比较 ,差异均有高度显著性意义 (P <0 0 1 )。结论　CVVH疗法可有效清除ARDS患者血管外肺水和各种应激激素、致炎介质 ,明显改善了ARDS患者肺部氧合功能及血流动力学指标 ,提高了抢救成功率     

关于奥运志愿者精神对党建教育意义的探析——让学生在参与中发现、实现自身的价值

奥运志愿者精神是北京奥运会的宝贵精神遗产。充分发挥奥运志愿者精神的社会教育作用，有利于提升当代大学生的奉献精神，激发其创新能力；同时，奥运志愿者精神也是培育大学生党员的重要载体。     

Elemental composition and water content of myelinated axons and glial cells in rat central nervous system

The distribution of elements (e.g. Na, Cl, K) and water in CNS cells is unknown. Therefore, electron probe X-ray microanalysis (EPMA) was used to measure water content and concentrations (mmol/kg dry or wet weight) of Na, Mg, P, S, Cl, K and Ca in morphological compartments of myelinated axons and glial cells from rat optic nerve and cervical spinal cord white matter. Axons in both CNS regions exhibited similar water content ( 90%), and relatively high concentrations (wet and dry weight) of K with low Na and Ca levels. The K content of axons was related to diameter, i.e. small axons in spinal cord and optic nerve had significantly less (25–50%) K than larger diameter axons from the same CNS region. The elemental composition of spinal cord mitochondria was similar to corresponding axoplasm, whereas the water content (75%) of these organelles was substantially lower than that of axoplasm. In glial cell cytoplasm of both CNS areas, P and K (wet and dry weight) were the most abundant elements and water content was approximately 75%. CNS myelin had predominantly high P levels and the lowest water content (33–55%) of any compartment measured. The results of this study demonstrate that each morphological compartment of CNS axons and glia exhibits a characteristic elemental composition and water content which might be related to the structure and function of that neuronal region.     

Pharmacokinetics of the 13C labeled anticancer agent temozolomide detected in vivo by selective cross-polarization transfer

The anticancer agent temozolomide labeled with ¹³C (8-Carbamoyl-3-13C-methylimidazo-[5,1-d]-1,2,3,5-tetrazin-4-(3H)-one), was noninvasively detected in subcutaneous RIF-1 tumors by a selective cross polarization ¹³C NMR method, at a field strength of 9.4T. Pharmacokinetics of the drug, at a dose of 150 mg/kg, were determined for intravenous and intraperitoneal modes of administration (three animals per mode). The half-life of the drug in the tumors was approximately 60 min. The uptake and clearance of the drug, however, varied significantly between individual hosts, for both modes of administration. These results demonstrate the feasibility of obtaining pharmacokinetics of anticancer agents for individual tumors without the need for a label that might modify drug activity (e.g., fluorine). The variability of the in vivo measurements, even within the same tumor model, demonstrates the necessity of directly monitoring the tumor to evaluate drug pharmacokinetics.     

Secretion of cathepsin B by human gliomas in vitro

There is evidence from investigations of non-CNS neoplasms that secreted proteolytic enzymes may facilitate tumour invasion by partially degrading extracellular matrix (ECM). Among the enzymes which may be involved are members of the cysteine proteinase superfamily and especially cathepsin B (CB). In the present investigation we have studied CB in human gliomas in vitro , concentrating particularly on CB secretion, as extracellular enzyme is of prime importance in this context. We have found that CB is secreted by gliomas in vitro as a latent zymogen, requiring activation. This has been confirmed by gel chromatography which indicated that CB is secreted as a 42 kDa proenzyme which may be proteolytically processed to an enzymatically active 29 kDa molecule. The inactive, high molecular weight, latent CB is stable at extracellular pH in contrast to the activated low molecular weight form which rapidly loses activity at this pH. We have also measured secretion of cysteine proteinase inhibitors (CPI), as their presence would have a direct influence on the effective activity of CB, and found that all of the gliomas secreted significant amounts of a CPI as assessed by papain inhibition. Our experiments suggest that a number of factors are involved in the regulation of extracellular glioma-derived CB activity. These include: rate of secretion of pro-CB, rate of CB activation, destabilization of CB at neutral pH and the presence of cysteine proteinase inhibitors.     

Chronic opioid treatment of neuroblastoma X dorsal root ganglion neuron hybrid F11 cells results in elevated GM1 ganglioside and cyclic adenosine monophosphate levels and onset of naloxone-evoked decreases in membrane K+ currents

Prolongation of the action potential duration of dorsal root ganglion (DRG) neurons by low (nM) concentrations of opioids occurs through activation of excitatory opioid receptors that are positively coupled via G_s regulatory protein to adenylate cyclase. Previous results suggested GM1 ganglioside to have an essential role in regulating this excitatory response, but not the inhibitory (APD-shortening) response to higher (μM) opioid concentrations. Furthermore, it was proposed that synthesis of GM1 is upregulated by prolonged activation of excitatory opioid receptor functions. To explore this possibility we have utilized cultures of hybrid F11 cells to carry out closely correlated electrophysiological and biochemical analyses of the effects of chronic opioid treatment on a homogeneous population of clonal cells which express many functions characteristic of DRG neurons. We show that chronic opioid exposure of F11 cells does, in fact, result in elevated levels of GM1 as well as cyclic adenosine monophosphate (AMP), concomitant with the onset of opioid excitatory supersensitivity as manifested by naloxone-evoked decreases in voltage-dependent membrane K⁺ currents. Such elevation of GM1 would be expected to enhance the efficacy of excitatory opioid receptor activation of the G_s/adenylate cyclase/cyclic AMP system, thereby providing a positive feedback mechanism that may account for the remarkable supersensitivity of chronic opioid-treated neurons to the excitatory effects of opioid agonists as well as antagonists. These in vitro findings may provide novel insights into the mechanisms underlying naloxone-precipitated withdrawal syndromes and opioid-induced hyperalgesia after chronic opiatf addiction in vivo. © 1995 Wiley-Liss, Inc.     

Splicing of the mitochondrial group-II intron rl1: conserved intron-exon interactions diminish splicing efficiency

The mitochondrial intron rI1 is a self-splicing group-II intron of algal mitochondria that can be transferred into chloroplasts from the green alga Chlamydomonas reinhardtii for in vivo investigations (Herdenberger et al. 1994). Thus, rI1 is a suitable system to compare in vitro and in vivo RNA processing. Interestingly, rI1 shows correct RNA splicing, although typical cis-acting exon-sequences (IBS2, δ) of group-II introns are lacking. In order to examine the effect of these exon-intron interactions on splicing, we introduced the endogenous mitochondrial IBS2 sequence in order to produce optimal IBS2-EBS2 base pairing. In addition, the first nucleotide of the 3′exon (δ′) was substituted to create an optimal δ-δ′ interaction. Neither of the two mutations, nor a combination of both, had any effect on the precision of the splice-site selection. Unexpectedly, introduction of IBS2 led to a reduction in the efficiency of the second splicing step in vitro but not in vivo. These findings lead us to conclude that trans-acting factors are present in vivo to optimize splicing efficiency. The possibility is discussed that these factors may, for example, stabilize tertiary intron structures that are a prerequisite for correct RNA processing. Furthermore, our data indicate that similar trans-acting factors promote correct intron splicing in chloroplasts and mitochondria. Received: 18 October / 4 December 1997     

Acute cardiac and pulmonary arrest after infusion of vancomycin with subsequent desensitization

J Allergy Clin Immunol 1997;100:853-4.