Adrenomedullin as a pancreatic hormone

Adrenomedullin (AM) is a multiregulatory peptide which is expressed in a wide range of tissues. In the pancreas, AM was first found in mammals, including man, and its colocalization with the pancreatic polypeptide (PP) was established in islet F cells. In addition, three different AM receptors have been characterized in B-cells. AM has been also located in the pancreatic cells of other vertebrate classes. The frequency and distribution of AM cells vary between different animals; they can be found scattered among the exocrine tissue, in the islets, or in ductal epithelia. The colocalization of AM with other hormones presents different patterns, although in birds, as in mammals, it seems to colocalize only with PP. The best-determined pancreatic AM function is the inhibition of insulin secretion in B-cells, which seems to be linked to a recently discovered binding protein, factor H. In relation to this physiological role, clinical data show that AM is raised in some groups of both types I and II diabetic patients and AM might have triggered the disease in a subset of them. On the other hand, AM pancreatic cells are also involved in the response to septic shock by increasing AM circulating levels. A third putative function is the inhibition of amylase secretion by the exocrine pancreatic cells. AM has been found in embryonic mammalian pancreas from the earliest stages of the development, colocalizing with all pancreatic hormones, although in adults only coexpression with PP is kept. AM may play a role in the growth and morphogenesis of the pancreas.     

Effect of black tea on histological and immunohistochemical changes in pancreatic tissues of normal and streptozotocin‐induced diabetic mice (Mus musculus)

The aim of the present study is to evaluate the effect of hot water extract of black tea in regenerating β cells in streptozotocin‐induced diabetic mice. Light microscopic examination of pancreatic sections of streptozotocin‐induced diabetic mice showed the acinar cells to be small, shrunken, and with deteriorated β cells. The dose of streptozotocin not only altered the function of β cells but also damaged the acinar region. The changes in acinar cells were coarsening of endoplasmic reticulation suggesting alteration in their secretory function. The control pancreatic tissue showed well‐defined granulated islets and dark β cells when stained with chrome hematoxylin and phloxine. Interestingly, pancreatic sections of diabetic mice fed with black‐tea extract showed regeneration of β cells and acinar region appeared normal with increased numbers of β cells. To understand the probable mechanism of action of black‐tea extract, we analyzed inducible nitric oxide synthase (iNOS) expression by immunohistochemistry and the results showed an increased iNOS levels in streptozotocin‐induced diabetic pancreas, and such high iNOS levels were inhibited in black‐tea extract treated mice. According to histological results obtained, it can be concluded that the black‐tea extract helps in regeneration of damaged pancreas and protects pancreatic β cells by its antioxidant action against nitrosative stress in streptozotocin‐induced diabetes. Microsc. Res. Tech., 2009. © 2009 Wiley‐Liss, Inc.     

Fluorescence lifetime imaging microscopy using near-infrared contrast agents

Although single-photon fluorescence lifetime imaging microscopy (FLIM) is widely used to image molecular processes using a wide range of excitation wavelengths, the captured emission of this technique is confined to the visible spectrum. Here, we explore the feasibility of utilizing near-infrared (NIR) fluorescent molecular probes with emission >700 nm for FLIM of live cells. The confocal microscope is equipped with a 785 nm laser diode, a red-enhanced photomultiplier tube, and a time-correlated single photon counting card. We demonstrate that our system reports the lifetime distributions of NIR fluorescent dyes, cypate and DTTCI, in cells. In cells labelled separately or jointly with these dyes, NIR FLIM successfully distinguishes their lifetimes, providing a method to sort different cell populations. In addition, lifetime distributions of cells co-incubated with these dyes allow estimate of the dyes' relative concentrations in complex cellular microenvironments. With the heightened interest in fluorescence lifetime-based small animal imaging using NIR fluorophores, this technique further serves as a bridge between in vitro spectroscopic characterization of new fluorophore lifetimes and in vivo tissue imaging.     

Small signal averaged transfer function model and controller design of modular solid state transformers

The prime objective of this paper is to design and develop simple and efficient closed loop controllers independently for each of the conversion stages of a Modular Solid State Transformer (MSST) for low/medium voltage applications. The controller design is based on small signal averaged transfer function model using topology independent black box approach. Hence it can be universally adopted for any choice of topologies. The independently designed controllers enhance the modularity of the apparatus such that extension and reduction of ac/dc voltage and power levels are possible by addition and removal of modules as and when required. This paves way for easy maintenance and replacement of modules. Further, the cost and complexity in control is reduced to enable large scale market penetration of the apparatus. Time and frequency response plots are illustrated to validate the performance of the individual converters with the designed closed loop controllers. The simple control design adopted for MSST is shown to mitigate power quality issues to a greater extent possible. Simulation and experimental results are presented which substantiate the appropriateness of the small signal model and hence the controllers designed for the MSST.     

Mapping protein expression in mouse pancreatic islets by immunolabeling and electron energy loss spectrum-imaging

A combination of immuno-electron microscopy and electron energy-loss spectrum-imaging was used to map the distributions of endocrine polypeptide hormones and proteins in mouse pancreatic islet of Langerhans. Tissue was analyzed from control animals and from mice that were heterozygous for the Anx7 gene, which defines a Ca2+/GTP-dependent membrane fusion and ion channel protein. The heterozygous Anx7 (+/-) mouse displays defects in IP3 receptor mediated Ca2+ signaling and insulin secretion. Therefore, information was obtained about the distributions of the hormones insulin and glucagon, as well as the proteins ANX7 and the IP3 receptor. Insulin secretion appears to be defective in the mutants. It was found from immunolabeling experiments that expression of the IP3 receptor is reduced in mutant islets compared to control islets. Subcellular distributions of sulfur and nitrogen obtained by electron energy-loss spectrum-imaging showed that the insulin concentrations of beta granules were essentially the same in control and mutant islets. By contrast, immunogold labeling of mutant islets shows more insulin immunoreactivity in the beta granules. It follows that insulin may be packaged differently in mutant islets, making antigenic determinants more available to the labeling antibody. The increased rate of insulin secretion in the hyperplastic mutant islets can be explained by compensatory increases in islet size, rather than by an increased insulin concentration in the beta cells. The results indicate that reduced ANX7 expression leads to defects in the IP3 receptor expression in the endocrine cells of the mutant mouse. Increased size of the islet or of adrenal medulla may be a compensatory mechanism for secretion defect by individual endocrine cells. Defects in IP3 receptor expression, and documented consequences of a Ca2+ signaling defect, lead to other changes in organelles such as the mitochondrial number in islet beta-cells. The effects and consequences of reduced ANX7 expression on mitochondria are evident in ultrastructural observations.     

Lobe variation effects of experimental diabetes and insulin replacement on rat prostate

We investigated the impact of diabetes with simultaneous and late insulin replacement on rat prostate growth during puberty, paying special attention to different prostatic lobes. Diabetes was induced by administration of streptozotocin (STZ) in 40-day-old male Wistar rats. A subset of diabetic rats underwent simultaneous insulin replacement (3 days after STZ administration), and another subset underwent a late insulin replacement (20 days after STZ administration). The ventral, dorsolateral, and anterior prostatic lobes were weighed and processed for histological, immunohistochemical, and morphometric analyses. Both diabetic and insulin-treated animals maintained low plasma testosterone (T) concentrations, whereas dihydrotestostenore (DHT) levels were normal. Diabetic animals had a decreased gain in absolute prostatic weight when compared to age-matched controls and insulin replacement animals. However, prostatic lobe weight in the diabetic animals was ～100% higher, even at the beginning of the experiment. Among the lobes, the anterior lobe showed the highest weight gain in diabetic and insulin replacement conditions. Epithelial cell proliferation in all lobes was significantly reduced in diabetic animals and significantly increased in insulin replacement animals, although apoptosis was unaltered. In conclusion, diabetes diminishes, but does not abolish, prostate growth during puberty. Even late insulin administration reduces the adverse effects of this disease on the prostate. In a scenario with both low insulin and T levels, DHT and other factors may play an important role in pubertal prostate growth. The adverse effects of diabetes on the rat prostate show a variation in lobe response, suggesting that diabetes may affect human prostate zones differently.     

Histomorphological and quantitative immunohistochemical changes in the rat pancreas during aging

Although the endocrine pancreas is the purpose of several deep investigations, morphological data referred to the effect of aging on the gland are not homogeneous. The purpose of the current work was to analyze the changes occurring in the pancreas of aged rats, with especial reference to the islet cell populations. Six young (Y), old (O) and senescent (S) male Sprague-Dawley rats were used. The pancreas tails were processed for light microscopy and studied by means of routine stains as well as by immunohistochemical identification of insulin-, glucagon-, somatostatin-, and pancreatic polypeptide- secreting cells (Dako Envision System, DAB as chromogen). A progressive pancreatic histoarchitecture distortion was found among the aged animals. Even when the alterations were not uniformly observed, they appeared more evident and severe in the S group. The S rats showed significantly increased volume density and cell density of the B cell population, as well as larger number of islet profiles, when compared to O rats. A significant progressive increment of adipose tissue was also evident in aged animals. No abnormal changes were detected in the nonB cell populations of the different groups.
The quantitative changes found in aged animals suggest a possible compensatory reaction of the B cell population in an attempt to curb the influence of diabetogenic factors mounting with advanced age.     

Average molecular weight determination of a polyester by NIR spectroscopy

The average molecular weight has been determined on a polyester additive product manufactured by a major chemical company. This determination is done during the polyester preparation (in-process) by fiber optics near infrared spectroscopy (NIR) using the UOP Guided Wave software. The disappearance of one of the starting materials with hydroxylic functionality (1415 nm) is monitored. Average molecular weights are determined from a calibration curve (average molecular weight versus absorbance) which itself is derived from polyester samples that have been analyzed by GPC (Gel Permeation Chromatography). The calibration curve is best described by a third-order mathematical model determined using the shareware program Kurv + for Windows®. The NIR and GPC methods generally agree to within 50–400 units.     

Multiphoton microscopy in life sciences

Near infrared (NIR) multiphoton microscopy is becoming a novel optical tool of choice for fluorescence imaging with high spatial and temporal resolution, diagnostics, photochemistry and nanoprocessing within living cells and tissues. Three‐dimensional fluorescence imaging based on non‐resonant two‐photon or three‐photon fluorophor excitation requires light intensities in the range of MW cm^?2 to GW cm^?2, which can be derived by diffraction limited focusing of continuous wave and pulsed NIR laser radiation. NIR lasers can be employed as the excitation source for multifluorophor multiphoton excitation and hence multicolour imaging. In combination with fluorescence in situ hybridization (FISH), this novel approach can be used for multi‐gene detection (multiphoton multicolour FISH). Owing to the high NIR penetration depth, non‐invasive optical biopsies can be obtained from patients and ex vivo tissue by morphological and functional fluorescence imaging of endogenous fluorophores such as NAD(P)H, flavin, lipofuscin, porphyrins, collagen and elastin. Recent botanical applications of multiphoton microscopy include depth‐resolved imaging of pigments (chlorophyll) and green fluorescent proteins as well as non‐invasive fluorophore loading into single living plant cells. Non‐destructive fluorescence imaging with multiphoton microscopes is limited to an optical window. Above certain intensities, multiphoton laser microscopy leads to impaired cellular reproduction, formation of giant cells, oxidative stress and apoptosis‐like cell death. Major intracellular targets of photodamage in animal cells are mitochondria as well as the Golgi apparatus. The damage is most likely based on a two‐photon excitation process rather than a one‐photon or three‐photon event. Picosecond and femtosecond laser microscopes therefore provide approximately the same safe relative optical window for two‐photon vital cell studies. In labelled cells, additional phototoxic effects may occur via photodynamic action. This has been demonstrated for aminolevulinic acid‐induced protoporphyrin IX and other porphyrin sensitizers in cells. When the light intensity in NIR microscopes is increased to TW cm^?2 levels, highly localized optical breakdown and plasma formation do occur. These femtosecond NIR laser microscopes can also be used as novel ultraprecise nanosurgical tools with cut sizes between 100 nm and 300 nm. Using the versatile nanoscalpel, intracellular dissection of chromosomes within living cells can be performed without perturbing the outer cell membrane. Moreover, cells remain alive. Non‐invasive NIR laser surgery within a living cell or within an organelle is therefore possible.     

中药材黄连颗粒度对近红外光谱的影响

近红外漫反射光谱易受样品颗粒度的影响。本文对10种不同粒度的黄连的近红外光谱进行分析,讨论粒度对黄连的近红外光谱强度的影响。结果发现,小粒度黄连的近红外光谱的重现性较好。当黄连粒度小于0.154 mm时,粒度变化对黄连的近红外光谱强度的影响较小。     

人体血糖微创和无创伤快速检测方法

概述国内外人体血糖微创伤检测方法和仪器的现状,介绍近年来人体血糖无创伤检测的研究方法,实验结果以及仪器研究进展,重点介绍近红外吸收光谱和光声光谱方法,并讨论无创伤检测方法存在的问题。微创伤方法能够测得比较准确的血糖值,是血糖测量的主要方法。无创伤血糖检测技术具有无痛、无感染,测量简单、快速等优点,目前尚处于研究阶段。     

近红外光谱技术检测牛奶中脂肪及蛋白质含量校正模型的建立

为实现牛奶成分的快速检测,研究了近红外光谱法在牛奶主要成分分析中的应用,重点对比了不同近红外区域的检测结果。研究中利用偏最小二乘法(PLS)建立校正模型,探讨了不同光谱区域和数据预处理对模型准确性的影响。模型结果表明在长波段(1700nm~2500nm)检测牛奶中脂肪及蛋白质含量的准确性最高。     

A promising new wavelength region for three-photon fluorescence microscopy of live cells

We report three-photon laser scanning microscopy (3PLSM) using a bi-directional pumped optical parametric oscillator (OPO) with signal wavelength output at λ= 1500 nm. This novel laser was used to overcome the high optical loss in the infrared spectral region observed in laser scanning microscopes and objective lenses that renders them otherwise difficult to use for imaging. To test our system, we performed 3PLSM auto-fluorescence imaging of live plant cells at λ= 1500 nm, specifically Spirogyra, and compared performance with two-photon excitation (2PLSM) imaging using a femtosecond pulsed Ti:Sapphire laser at λ= 780 nm. Analysis of cell viability based on cytoplasmic organelle streaming and structural changes of cells revealed that at similar peak powers, 2PLSM caused gross cell damage after 5 min but 3PLSM showed little or no interference with cell function after 15 min. The λ= 1500 nm OPO is thus shown to be a practical laser source for live cell imaging.     

小麦和大豆蛋白质含量的近红外漫反射光谱分析实验研究

近红外漫反射光谱分析技术是一种新的光谱分析技术。本文详细论述了近红外漫反射光谱学原理及分析技术,对影响近红外漫反射光谱技术的主要因素进行了探讨,首次在固定滤光片式近红外漫反射分析仪上应用了模拟导数光谱的差分变换方法并得到了小麦和大豆蛋白质含量分析测定的满意结果。     

近红外光谱成像分析技术的应用进展

近红外光谱成像是近年来快速发展起来的一种新的分析手段,尤其在化学成分分析和污染物的空间分布测定方面,近红外图像技术具有实现快速、无损、原位、在线分析的特点。通过近红外图像不但能够得到生物组织和化学成分的清晰轮廓和分布信息,而且可以通过化学计量学方法实现对特定目标成分的定性和定量分析。本文简要介绍近红外光谱成像技术的原理、应用和发展特点,图像光谱的前处理方法,图像提取所需化学特征信息的化学计量学算法,以及近红外成像分析技术在医药领域,农业和食品等领域最新的应用和研究进展。     

发动机润滑油含水量近红外特征波段选取

应用近红外光谱技术结合间隔偏最小二乘法,探讨发动机润滑油中含水率检测的特征波段及检测方法。采用间隔偏最小二乘法对发动机润滑油含水量的近红外光谱特征波段进行选择,结合偏最小二乘回归建模方法对所选波段进行验证。结果表明:选用7 432～6 321 cm-1和5 583～4 846 cm-1 2个波段建模可以得到与全谱一致的预测结果,从而实现了模型的简化,为润滑油中含水率近红外光谱分析提供理论依据。     

Two-photon excited lifetime imaging of autofluorescence in cells during UV A and NIR photostress

By monitoring coenzyme autofluorescence modifications. as an indicator of cell damage. the cellular response to femtosecond near-infrared (NIR) radiation (two-photon absorption) was compared with exposure to low-power UV A radiation (one-photon absorption). Excitation radiation from a tunable Ti-sapphire laser. focused through highnumerical- aperture microscope optics. provided diffractionlimited mlcrobeams of an adjustable peak power. Laser scanning NIR microscopy was used to detect spatially the intracellular distribution of fluorescent coenzymes by fluorescence intensity imaging as well as fluorescence lifetime imaging (_T-mapping). Upon the onset of UV or NIR exposure. Chinese hamster ovary cells exhibited blue/green autofluorescence witq a mean lifetime of 2·2 ns. which was attributed to NAD(P)H in mitochondria. Exposure to 365 nm radiation from a high-pressure mercury lamp (1 m W. 300 J cm^-2 ) resulted in oxidative stress correlated with increased autofluorescence intensity. onset of nuclear fluorescence. and a fluorescence lifetime decrease. The cellular response to femtosecond NIR micro beams depended significantly on peak power. Peak powers above a threshold value of about 0·5kW (average power: 6mW). 0·55kW (7mW) and 0·8kW (lOmW) at 730nm. 760nm and 800nm. respectively. resulted in the onset of short-lived luminescence with higher intensity (100x) than the intracellular NAD(P)H fluorescence. This luminescence. accompanied by destruction of cellular morphology. was localized and occurred in the mitochondrial region. In contrast. beams at a power of less than 0·5 kW allowed nondestructive fluorophore detection with high spatial and temporal resolution without modification of cellular redox state or cell morphology.     

Diabetes screening by telecentric digital holographic microscopy

Diabetes is currently the world's fastest growing chronic disease and it is caused by deficient production of insulin by the endocrine pancreas or by abnormal insulin action in peripheral tissues. This results in persistent hyperglycaemia that over time may produce chronic diabetic complications. Determination of glycated haemoglobin level is currently the gold standard method to evaluate and control sustained hyperglycaemia in diabetic people. This measurement is currently made by high‐performance liquid chromatography, which is a complex chemical process that requires the extraction of blood from the antecubital vein. To reduce the complexity of that measurement, we propose a fully‐optical technique that is based in the fact that there are changes in the optical properties of erythrocytes due to the presence of glucose‐derived adducts in the haemoglobin molecule. To evaluate these changes, we propose to perform quantitative phase maps of erythrocytes by using telecentric digital holographic microscopy. Our experiments show that telecentric digital holographic microscopy allows detecting, almost in real time and from a single drop of blood, significant differences between erythrocytes of diabetic patients and healthy patients. Besides, our phase measurements are well correlated with the values of glycated haemoglobin and the blood glucose values.     

阴囊闭合性损伤的CT与MRI诊断价值

目的探讨CT与MRI对阴囊闭合性损伤的诊断价值。方法回顾性分析12例临床证实的阴囊损伤的CT和（或）MRI资料。12例患者,4例同时有CT与MRI资料,5例、3例分别进行CT、MRI检查。结果阴囊壁肿胀11例,鞘膜积液9例,白膜下血肿2例,睾丸挫伤伴血肿6例,附睾挫伤2例,睾丸白膜破裂1例。结论 CT简单快速、较为准确,尤其适于急性期检查,MRI显示阴囊损伤更为精确,更适用于该病的重复检查和疗效观察。     

Fluorescence lifetime imaging of lignin autofluorescence in normal and compression wood

Wood cell walls fluoresce as a result of UV and visible light excitation due to the presence of lignin. Fluorescence spectroscopy has revealed characteristic spectral differences in various wood types, notably normal and compression wood. In order to extend this method of characterising cell walls we examined the fluorescence lifetime of wood cell walls using TCSPC (Time‐Correlated Single Photon Counting) as a method of potentially detecting differences in lignin composition and measuring the molecular environment within cell walls. The fluorescence decay curves of both normal and compression wood from pine contain three exponential decay components with a mean lifetime of τ_m = 473 ps in normal wood and 418 ps in compression wood. Lifetimes are spatially resolved to different cell wall layers or cell types where individual lifetimes are shown to have a log‐normal distribution. The differences in fluorescence lifetime observed in pine compression wood compared to normal wood, are associated with known differences in cell wall composition such as increased p‐hydroxyphenyl content in lignin as well as novel deposition of β(1,4)‐Galactan. Our results indicate increased deposition of lignin fluorophores with shorter lifetimes in the outer secondary wall of compression wood. We have demonstrated the usefulness of fluorescence lifetime imaging for characterising wood cell walls, offering some advantages over conventional fluorescence imaging/spectroscopy. For example, we have measured significant changes in fluorescence lifetime resulting from changes to lignin composition as a result of compression wood formation that complement similar changes in fluorescence intensity.