bluuebunny/crossref_metadata_2025 huggingface dataset:
A new look at the cellular scaffold by embedment‐free electron microscopy method
Authors: Gajkowska Barbara , Wojesódzka Urszula
Published: May 2007

The basic scaffold of most cells is afforded by the cytoskeleton (comprising microfilaments, intermediate filaments and the microtubules). The conventional methods of electron microscopy fail to visualize filamentous cell structure. They can show only these filaments lying at the section surface. Heavy metal staining (I), and the optical properties of the resins used for embedding are similar to those of proteins hence most proteinaceous structures remain unresolved and the cytoplasm seems to be quite homogenous (II). Aldehyde fixation could cross‐link proteins and lead to the emergence of artificial structures (III). These limitations may be overcome by the use of the embedment‐free electron microscopy (EF‐EM). This technique present cellular scaffold as a purified, isolated, three‐dimensional network with various thickness of filaments. Our study on the dynamic aspect of cellular scaffold indicate that the thickness and arrangement of filaments depend on cell type and both physiological or pathological environments. Thank also to the adaptation of immunocytochemistry to EF‐EM it was possible to understand the nuclear matrix and cytomatrix structure in relation to function. Thus, combination these methods revealed findings suggesting the nuclear homing of proapoptotic proteins and their association with intermediate filaments.
Somatotroph to thyrotroph cell transdifferentiation during experimental hypothyroidism ‐ a light and electron‐microscopy study
Authors: Radian S. , Coculescu M. , Morris J. F.
Published: May 2007

Somatotroph and thyrotroph pituitary cells share a common precursor cell expressing the transcription factor Pitl in ontogeny. Cells expressing both thyrotropin (TSH) and growth‐hormone (GH) are found in adult rat pituitary and in human pituitary adenomas in acromegaly, and these tumors contain both thyrotropin‐releasing hormone (TRH) and the TRH receptors (TRHR). It has been shown that stimulation of TSH expression in primary hypothyroidism promotes changes suggestive of somatotroph to thyrotroph cell transdifferentiation. We tested this hypothesis and the role of TRH in experimental primary hypothyroidism in rats. Adult female Long‐Evans rats, 6 months old, were administered the antithyroid drug methimazole (0,1% w/v) in the drinking water for 42 days. Animals were sacrificed by perfusion fixation under anaesthesia at weekly intervals and pituitary tissue processed in acrylic resin for immunofluorescence and immuno‐electronmicroscopy for TSH, GH and TRHR. In the hypothyroid rat pituitary immunofluorescent somatotrophs were greatly reduced in number and gradually replaced by thyrotrophs during methimazole administration. Colocalization of GH and TSH in the same cell was noted. Immunoelectronmicroscopy demonstrated the development of enlarged thyrotrophs with dilated rough endoplasmic reticulum containing an electron‐dense material and intracisternal granules, both of which are immunoreactive for TSH (‘thyroidectomy cells’). The somatotrophs showed reduced GH immunoreactivity and also the presence of TSH‐type, small‐size secretory granules. This suggests that, the greatly increased number of TSH‐cells in methimazole‐induced‐hypothyroidism is due, at least partially, to the transdifferentiation of somatotroph into thyrotroph cells. TRHR immunofluorescence was expressed in many somatotrophs in normal rat pituitary and unlike immunoreactive GH, its expression was enhanced during hypothyroidism. The number of TRHR‐immunoreactive cells increased in parallel with the number of TSH‐immunoreactive cells. This indicates a role for TRH stimulation in the transdifferentiation process. Taken together, these data suggest that, in addition to the cell mutation mechanism involving an early totipotential progenitor cell, transdifferentiation of existing somatotroph cells also plays a part in the pathogenesis of multihormonal GH‐secreting adenomas.
Relationship of tobacco smoking with GSTM1 gene polymorphism in laringeal cancer
Authors: Bardakci F. , Canbay E. , Degerli Naci , Coban L. , Canbay E. I.
Published: May 2007

This paper aimed to analyze the association of polymorphism of GSTM1 0/0 genotype with laryngeal cancer along a hospital based case‐control study. Polymorphisms of GSTM1 0/0 of samples from 36 patients with laryngeal cancer and 35 healthy controls were detected by PCR method. The reaction used as GSTM1 primers, using the sequence sense: 5′‐CTGCCCTACTTGGATTGATGGG‐3′ and antisense: 5′‐TGGATTGTAGCAGATCATGC‐3′. N Acetyl transferase 1 (NAT1) gene using the primers sense: 5′‐TAAAAGTAAAATGATTTGCTTTCG‐3′ and antisense: 5′‐GCTTTCTAGCATAAATCACCAA‐3′ was used as internal positive control. Two sided 2 and multivariation analysis were used to analyse the results. The proportions of GSTM1 deleted genotype in cases and controls were 47.2% and 54.3%, respectively. There was significant increment of GSTM 0/0 genotype frequency in moderate smokers group of patients compared to control (P=0.033, OR= 4.78, 95% CI=1.30‐7.13). We conclude that GSTM1 deleted genotype may be a genetic susceptibility marker for laryngeal cancer whose exposed to low doses carcinogens. The absence of this enzyme seems to have a role in the development of laryngeal cancer, in which the mechanism still needs further investigation.
Apoptotic rate in patients with myelodisplastic syndrome treated with modulatory compounds of pro‐apoptotic cytokines
Authors: Moldoveanu Elena , Moicean Andreea , Vidulescu Cristina , Marta Daciana , Colita Adriana
Published: May 2007

Excessive apoptosis has a central role in ineffective hematopoiesis in myelodysplastic syndrome (MDS). The aim of the study was to quantify apoptosis and Bcl‐2 expression in patients with MDS and to use these parameters in the evaluation of treatment efficacy with compounds modulating proapoptotic cytokines. Bone marrow (BM) samples from eight MDS patients were studied: four with refractory anemia and four with refractory anemia with ringed sideroblasts. Two patients with Hodgkin disease without BM determination were studied for control. Therapy consisted in administration of pentoxyphylline, dexamethasone and ciprofloxacin. Biochemical assay of apoptosis and Bcl‐2 was performed using annexin V‐biotin conjugate antibody and anti‐human Bcl‐2 antibody respectively, followed by streptavidine‐peroxidase conjugate, and peroxidase substrate. Ultrastructural investigation of BM samples was performed with standard electron microscopy techniques. Most of BM hematopoietic cells in the MDS patients had ultrastructural features of various stages of apoptosis including chromatin condensation and margination, cytoplasm condensation and budding of nuclear and plasma membranes to produce apoptotic bodies. Bcl‐2 expression showed an inverse correlation with the rate of the apoptotic process. Periodic evaluation of these two parameters has shown an increase of Bcl‐2 expression and a decrease of apoptotic rate in patients who had responded to the treatment. Response to the treatment was appreciated in accordance with their transfusion needs. Treatment efficiency diminished in time. The rate of apoptosis was inversely correlated with the level of Bcl‐2 expression. These results confirm the importance of the apoptotic process evaluation in monitoring MDS treatment.
Endoplasmic reticulum Ca2+ homeostasis and neuronal death
Authors: Verkhratsky A. , Toescu E. C.
Published: May 2007

The endoplasmic reticulum (ER) is a universal signalling organelle, which regulates a wide range of neuronal functional responses. Calcium release from the ER underlies various forms of intracellular Ca2+ signalling by either amplifying Ca2+ entry through voltage‐gated Ca2+ channels by Ca2+‐induced Ca2+ release (CICR) or by producing local or global cytosolic calcium fluctuations following stimulation of metabotropic receptors through inositol‐1,4,5‐trisphosphate‐induced Ca2+ release (IICR). The ER Ca2+ store emerges as a single interconnected pool, thus allowing for a long‐range Ca2+ signalling via intra‐ER tunnels. The fluctuations of intra‐ER free Ca2+ concentration regulate the activity of numerous ER resident proteins responsible for post‐translational protein folding and modification. Disruption of ER Ca2+ homeostasis results in the developing of ER stress response, which in turn controls neuronal survival. Altered ER Ca2+ handling may be involved in pathogenesis of various, neurodegenerative diseases including brain ischemia and Alzheimer dementia.
Plasticity of purine release during cerebral ischemia: clinical implications?
Authors: Pearson T. , Currie Ailsa J. , Etherington Lori‐An V. , Gadalla Anne E. , Damian Karen , Llaudet E. , Dale N. , Frenguelli B. G.
Published: May 2007

Adenosine is a powerful modulator of neuronal function in the mammalian central nervous system. During a variety of insults to the brain, adenosine is released in large quantities and exerts a neuroprotective influence largely via the A1receptor, which inhibits glutamate release and neuronal activity. Using novel enzyme‐based adenosine sensors, which allow high spatial and temporal resolution recordings of adenosine release in real time, we have investigated the release of adenosine during hypoxia/ischemia in thein vitrohippocampus. Our data reveal that during the early stages of hypoxia adenosine is likely releasedper seand not as a precursor such as cAMP or an adenine nucleotide. In addition, repeated hypoxia results in reduced production of extracellular adenosine and this may underlie the increased vulnerability of the mammalian brain to repetitive or secondary hypoxia/ischemia.
Human Natural Killer cell receptors: insights into their molecular function and structure
Authors: Biassoni R. , Cantoni Claudia , Marras D. , Giron‐Michel J. , Falco Michela , Moretta L. , Dimasi N.
Published: May 2007

NK cells express receptors characterized by opposite functions that finely regulate their activities. Among inhibitory receptors, some are specific for different groups of MHC class I alleles, while others are still orphan receptors. On the contrary, various activating receptors are involved in the triggering of NK‐mediated natural cytotoxicity. In general, their engagement induces human NK cells to kill target cells that are either HLA class I‐negative or ‐deficient. Thus, the process of NK cell triggering mediated by Natural Cytotoxicity Receptors can be mainly considered as a non MHC‐restricted mechanism. Here, a brief description of the molecular nature of these receptors, as well as, of their 3D‐structures and of the implications for ligand recognition, is given.
Peroxisome biogenesis and the role of protein import
Authors: Brown Laura‐Anne , Baker Alison
Published: May 2007

Peroxisomes are metabolic organelles with enzymatic content that are found in virtually all cells and are involved in β‐oxidation of fatty acids, hydrogen peroxide‐based respiration and defence against oxidative stress. The steps of their biogenesis involves “peroxins”, proteins encoded by PEX genes. Peroxins are involved in three key stages of peroxisome development: (1) import of peroxisomal membrane proteins; (2) import of peroxisomal matrix proteins and (3) peroxisome proliferation. Of these three areas, peroxisomal matrix‐protein import is by far the best understood and accounts for most of the available published data on peroxisome biogenesis. Defects in peroxisome biogenesis result in peroxisome biogenesis disorders (PBDs), which although rare, have no known cure to‐date. This review explores current understanding of each key area in peroxisome biogenesis, paying particular attention to the role of protein import.
Immunohistochemical assessment of proliferating cell nuclear antigen in primary hepatocellular carcinoma and dysplastic nodules
Authors: Saftoiu A. , Ciurea T. , Georgescu Claudia , Banita Monica , Comanescu Violeta , Rogoveanu I. , Gorunescu F. , Georgescu I.
Published: May 2007

A complementary way for the assessment of HCC prognosis is represented by the analysis of molecular markers. Thus, immunohistochemical assessment of proliferation can describe tumor aggressiveness, probability of local recurrence or metastasis potential, being very useful for the assessment of recurrence‐free survival and survival until death. The aim of our study was to assess proliferating cell nuclear antigen activity in HCC and dysplastic nodules as compared with surrounding nonneoplasic areas. Immunohistochemical techniques were thus performed on the samples obtained by ultrasound‐guided liver biopsies or intraoperative biopsies, in 32 patients with HCC, as well as in 3 patients with dysplastic nodules ocurring in liver cirrhosis. Expression of PCNA within extranodular areas of the HCC patients in the absence or presence of cirrhosis, was increasing from 40% to 70%, respectively. PCNA expression further increased within intranodular areas of dysplastic nodules and HCC, to 100% and 96.88%, respectively. A progressive increase of the mean values of PCNA‐LI was also observed from extranodular areas without or with cirrhosis, towards intranodular areas of dysplastic nodules and HCC (4.2%, 6.8%, 31.9%, respectively). Dysplastic nodules can thus be considered lesions with a high‐proliferation rate, representing an early stage of hepatocarcinogenesis. This supported the current recommendations for borderline hepatocellular nodules identified by ultrasound, which indicate an aggressive treatment similar to malignant lesions. In summary, we demonstrated a progressively increasing rate of cellular proliferation, from extranodular non‐neoplasic areas to intranodular areas (dysplastic nodules and HCC), as reflected by an increased expression of proliferating cell nuclear antigen labelling index.
Sertoli‐Leydig cell tumor ‐ a rare androgen secreting ovarian tumor in postmenopausal women: case report and review of literature
Authors: Gheorghisan‐Galateanu Ancuta , Fica Simona , Terzea Dana Cristina , Caragheorgheopol Andra , Horhoianu V.
Published: May 2007

Sertoli‐Leydig cell tumors (SLCT) constitute only 1‐0.5% of all primary ovarian neoplasms. We report a SLCT in a postmenopausal woman aged 69 years. The physical examination revealed severe hirsutism. Basal hormonal evaluation showed high plasma testosterone and estradiol values, with suppressed plasma gonadotropins. Computer tomograph scan revealed a right ovarian tumor mass of 4,3/3 cm, confirming an androgen secreting ovarian tumor. The histopathological and immunocytochemical examination established the diagnosis of well differentiated Sertoli‐Leydig cell tumor. The tumor was positive for cytokeratin KL 1 and S‐100 protein and, in isolated tumor cells, positive for alpha‐fetoprotein. Postsurgical evolution was favorable; controls after 6 months and 3,5 years showed marked reduction of hirsutism, normal plasma testosterone values and gonadotropins in normal postmenopausal range. We discuss the complex aspects of etiology and pathogenesis, the clinical and hormonal settings, the role of immunocytochemical markers in diagnosis, as well as the therapy and the prognostic features of this ovarian tumor.
Discovery of the Porosome: revealing the molecular mechanism of secretion and membrane fusion in cells
Authors: Jena B. P.
Published: May 2007

Secretion and membrane fusion are fundamental cellular processes involved in the physiology of health and disease. Studies within the past decade reveal the molecular mechanism of secretion and membrane fusion in cells. Studies reveal that membrane‐bound secretory vesicles dock and fuse at porosomes, which are specialized plasma membrane structures. Swelling of secretory vesicles result in a build‐up of intravesicular pressure, which allows expulsion of vesicular contents. The discovery of the porosome, its isolation, its structure and dynamics at nm resolution and in real time, its biochemical composition and functional reconstitution, are discussed. The molecular mechanism of secretory vesicle fusion at the base of porosomes, and vesicle swelling, have been resolved. With these findings a new understanding of cell secretion has emerged and confirmed by a number of laboratories.
Functions of erg K+channels in excitable cells
Authors: Schwarz Jürgen R. , Bauer Christiane K.
Published: May 2007

Ether‐à‐go‐go‐related gene (erg) channels are voltage‐dependent K+channels mediating inward‐rectifying K+currents because of their peculiar gating kinetics. These characteristics are essential for repolarization of the cardiac action potential. Inherited and acquired malfunctioning of erg channels may lead to the long QT‐syndrome. However, erg currents have also been recorded in many other excitable cells, like smooth muscle fibres of the gastrointestinal tract, neuroblastoma cells or neuroendocrine cells. In these cells erg currents contribute to the maintenance of the resting potential. Changes in the resting potential are related to cell‐specific functions like increase in hormone secretion, frequency adaptation or increase in contractility.
Plasticity of GABAergic synapses in the neonatal rat hippocampus
Authors: Gaïarsa J.‐L.
Published: May 2007

While the development and plasticity of excitatory synaptic connections have been studied into detail, little is known about the development of inhibitory synapses. As proposed for excitatory synapses, recent studies have indicated that activity‐dependent forms of synaptic plasticity, such as long‐term potentiation and long‐term depression, may play a role in the establishment of functional inhibitory synaptic connections. Here, I review these different forms of plasticity and focus on their possible role in the developing neuronal network.
Regulation of recombinant human brain tandem P domain K+channels by hypoxia: a role for O2in the control of neuronal excitability?
Authors: Kemp P. J. , Peers C. , Lewis A. , Miller Paula
Published: May 2007

The tandem P domain potassium channels, TREK1 and TASK1, are expressed throughout the brain but expression patterns do not significantly overlap. Since normal pO2in central nervous tissue is as low as 20 mmHg and can decrease even further in ischemic disease, it is important that the behaviour of human brain ion channels is studied under conditions of acute and chronic hypoxia. This is especially true for brain‐expressed tandem P‐domain channels principally because they are important contributors to neuronal resting membrane potential and excitability. Here, we discuss some recent data derived from two recombinant tandem P‐domain potassium channels, hTREK1 and hTASK1. Hypoxia represents a potent inhibitory influence on both channel types and occludes the activation by arachidonic acid, intracellular acidosis and membrane deformation of TREK1. This casts doubt on the idea that TREK1 activation during brain ischemia might facilitate neuroprotection via hyperpolarising neurons in which it is expressed. Interestingly, hypoxia is unable to regulate alkalotic inhibition of TREK1 suggesting that this channel may be more intimately involved in control of excitability during physiological or pathological alkalosis.
Molecular mechanisms of neuroprotective action of immunosuppressants ‐ facts and hypotheses
Authors: Kaminska Bozena , Gaweda‐Walerych Katarzyna , Zawadzka Malgorzata
Published: May 2007

Cyclosporin A (CsA) and FK506 (Tacrolimus) are short polypeptides which block the activation of lymphocytes and other immune system cells. Immunosuppressants exert neuroprotective and neurotrophic action in traumatic brain injury, sciatic nerve injury, focal and global ischemia in animals. Their neuroprotective actions are not understood and many hypotheses have been formed to explain such effects. We discuss a role of drug target ‐ calcineurin in neuroprotective action of immunosuppressants. Protein dephosphorylation by calcineurin plays an important role in neuronal signal transduction due to its ability to regulate the activity of ion channels, glutamate release, and synaptic plasticity.In vitroFK506 protects cortex neurons from NMDA‐induced death, augments NOS phosphorylation inhibiting its activity and NO synthesis. However,in vivoexperiments demonstrated that FK506 in neuroprotective doses did not block excitotoxic cell death nor did it alter NO production during ischemia/reperfusion. Tissue damage in ischemia is the result of a complex pathophysiological cascade, which comprises a variety of distinct pathological events. Resident non‐neuronal brain cells respond rapidly to neuronal cell death and may have both deleterious and useful role in neuronal damage. There is increasing evidence that reactive gliosis and post‐ischemic inflammation involving microglia contribute to ischemic damage. We have demonstrated that FK506 modulates hypertrophic/proliferative responses and proinflammatory cytokine expression in astrocytes and microglia in vitro and in focal transient brain ischemia. Our findings suggest that astrocytes and microglia are direct targets of FK506 and modulation of glial response and inflammation is a possible mechanism of FK506‐mediated neuroprotection in ischemia.
Anti‐atherosclerotic effects of vitamin E – myth or reality?
Authors: Munteanu Adelina , Zingg J.‐M. , Azzi A.
Published: May 2007

Atherosclerosis and its complications such as coronary heart disease, myocardial infarction and stroke are the leading causes of death in the developed world. High blood pressure, diabetes, smoking and a diet high in cholesterol and lipids clearly increase the likelihood of premature atherosclerosis, albeit other factors, such as the individual genetic makeup, may play an additional role. Several epidemiological studies and intervention trials have been performed with vitamin E, and some of them showed that it prevents atherosclerosis. For a long time, vitamin E was assumed to act by decreasing the oxidation of LDL, a key step in atherosclerosis initiation. However, at the cellular level, vitamin E acts by inhibition of smooth muscle cell proliferation, platelet aggregation, monocyte adhesion, oxLDL uptake and cytokine production, all reactions implied in the progression of atherosclerosis. Recent research revealed that these effects are not the result of the antioxidant activity of vitamin E, but rather of precise molecular actions of this compound. It is assumed that specific interactions of vitamin E with enzymes and proteins are at the basis of its non‐antioxidant effects. Vitamin E influences the activity of several enzymes (e.g.PKC, PP2A, COX‐2, 5‐lipooxygenase, nitric oxide synthase, NADPH oxidase, superoxide dismutase, phopholipase A2) and modulates the expression of genes that are involved in atherosclerosis (e.g.scavenger receptors, integrins, selectins, cytokines, cyclins). These interactions promise to reveal the biological properties of vitamin E and allow designing better strategies for the protection against atherosclerosis progression.
Role of human prostasomes in the activation of spermatozoa
Authors: Arienti G. , Carlini E. , Saccardi C. , Palmerini C. A.
Published: May 2007

Prostasomes are small vesicles of prostatic origin contained in human semen. Their composition is peculiar under many aspects. Cholesterol is abundant and many proteins are endowed with enzymatic or other activities. The function of prostasomes has been amply debated and several hypotheses have been put forward. The liquefaction of semen, spermatozoa motility, antibacterial activity and immunological functions have been related to prostasomes. Under certain aspects, prostasomes resemble synaptosomes. The fusion of prostasomes to spermatozoa enriches spermatozoa with cholesterol and causes bursts of cytoplasmic sperm calcium. The interaction of spermatozoa and prostasomes should be limited to vagina since prostasomes are immobile and do not follow spermatozoa in the superior female genital tract. Calcium bursts would increase spermatozoa motility, where cholesterol would decapacitate spermatozoa, so preventing untimely activation. Since spermatozoa receive many different molecules from prostasomes, additional effects are also possible. Prostasomes makes spermatozoa more apt to be activated by progesterone in the proximity of the ovum. Therefore, the fusion between spermatozoa and prostasomes would influence spermatozoa behaviour under many aspects and might be relevant for fecundation. The richness of molecular species in prostasomes is amazing and these small vesicles are expected to lead to many more discoveries in the field of human reproduction.
The development of larger cells that spontaneously escape senescence ‐ a step during the immortalization of a human cancer cell line
Authors: Diaconu Carmen C. , Bleotu Coralia , Chivu Mihaela , Alexiu Irina , Petrusca Daniela , Anton Gabriela , Achim Ruxandra , Ruta Simona M. , Cernescu C.
Published: May 2007

There are few information concerning the changes associated with the transition interval when slow growing, primary explanted human cancer cells are displaced by new selected faster growing cells and became an immortal cell line. In a previous paper (J. Cell. Mol. Med., 5: 49–59, 2001) we described the TV cell line derived from a laryngeal tumor which harbors human papillomavirus (HPV) gene sequences throughout more than sixty in vitro passages. In this paper we analyze the modifications observed during the crisis interval when significant amount of cells senesce but occasional cells acquire some mutations that make them immortal. Confocal microscopy analysis revealed the heterogeneity of the cells in terms of their size and nucleus/cell ratio. Proliferation capacity was assessed by flow cytometry analyzing DNA content and expression of transferrin receptor (CD71). We discussed the possibility that HPV genome sequences alleviate a proliferation block during the crisis growth arrest of human larynx carcinoma cell line and the possibility that the cells monitor their size and growth by measuring the levels of some protein whose synthesis is coupled to cell development.
Changes in oxidative balance in rat pericytes exposed to diabetic conditions
Authors: Manea A. , Constantinescu Elena , Popov Doina , Raicu Monica
Published: May 2007

Recent data indicate that the oxidative stress plays an important role in the pathogenesis of diabetes and its complications such as retinopathy, nephropathy and accelerated atherosclerosis. In diabetic retinopathy, it was demonstrated a selective loss of pericytes accompanied by capillary basement membrane thickening, increased permeability and neovascularization. This study was designed to investigate the role of diabetic conditions such as high glucose, AGE‐Lysine, and angiotensin II in the modulation of antioxidant enzymes activities, glutathione level and reactive oxygen species (ROS) production in pericytes. The activity of antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and total glutathione (GSH) was measured spectrophotometrically. The production of ROS was detected by spectrofluorimetry and fluorescence microscopy after loading the cells with 2′‐7′ dichlorofluoresceine diacetate; as positive control H2O2 was used. Intracellular calcium was determined using Fura 2 AM assay. The results showed that the cells cultured in high glucose alone, do not exhibit major changes in the antioxidant enzyme activities. The presence of AGE‐Lys or Ang II induced the increase of SOD activity. Their combination decreased significantly GPx activity and GSH level. Athree times increase in ROS production and a significant impairment of intracellular calcium homeostasis was detected in cells cultured in the presence of the three pro‐diabetic agents used. In conclusion, our data indicate that diabetic conditions induce in pericytes: (i) an increase of ROS and SOD activity, (ii) a decrease in GPx activity and GSH level, (iii) a major perturbation of the intracellular calcium homeostasis. The data may explain the structural and functional abnormalities of pericytes characteristic for diabetic retinopathy.
S‐Glutathionylation: from redox regulation of protein functions to human diseases
Authors: Giustarini Daniela , Rossi R. , Milzani A. , Colombo R. , Dalle‐Donne Isabella
Published: May 2007

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) play an integral role in the modulation of several physiological functions but can also be potentially destructive if produced in excessive amounts. Protein cysteinyl thiols appear especially sensitive to ROS/RNS attack. Experimental evidence started to accumulate recently, documenting that S‐glutathionylation occurs in a number of physiologically relevant situations, where it can produce discrete modulatory effects on protein function. The increasing evidence of functional changes resulting from this modification, and the growing number of proteins shown to be S‐glutathionylated both in vitro and in vivo support this contention, and confirm this as an attractive area of research. S‐glutathionylated proteins are now actively investigated with reference to problems of biological interest and as possible biomarkers of human diseases associated with oxidative/nitrosative stress.
Coenzyme Q10inhibits mitochondrial complex‐1 down‐regulation and nuclear factor‐kappa B activation
Authors: Ebadi M. , Sharma S. K. , Wanpen S. , Amornpan A.
Published: May 2007

We have used control‐homozygous weaver mutant, and ‐heterozygous weaver mutant mice in order to explore the basic molecular mechanism of neurodegeneration and the neuroprotective potential of coenzyme Q10. Homozygous weaver mutant mice exhibited progressive neurodegeneration in the hippocampus, striatum, and cerebellum, and a reduction in the striatal levels of dopamine and coenzyme Qs (Q9and Q10) without any significant changes in norepinephrine and serotonin. Mitochondrial complex‐1 was down regulated; whereas nuclear factor‐kappa B was up regulated in homozygous weaver mutant mice. Rotenone inhibited complex‐1, enhanced nuclear factor‐kappa B, and caused apoptosis in human dopaminergic (SK‐N‐SH) neurons; whereas nuclear factor‐kappa B antibody suppressed rotenone‐induced apoptosis, suggesting that enhancing coenzyme Q10synthesis and suppressing the induction of NF‐kappa B, may provide neuroprotection.
Expression of Dishevelled‐1 in wound healing after acute myocardial infarction: possible involvement in myofibroblast proliferation and migration
Authors: Chen Lijun , Wu Qingfeng , Guo Feng , Xia Beili , Zuo Ji
Published: May 2007

One of our previous studies indicated that the expression of β‐catenin, which is the key factor of wnt‐frizzled pathway, increased significantly in the ischemic area of the rat heart 7 days after myocardial infarction (MI). Together with the results of other recent studies, we made an assumption that wnt‐frizzled pathway may be involved in the controlled cell proliferation and migration during repair processes after MI. To verify this assumption we tried to investigate the expression of another signal transduction molecule called Dishevelled in wnt‐frizzled pathway during the wound healing process after MI. The left descending coronary arteries of rats were ligated to induce MI. Immunohistochemistry SABC method and in situ hybridization were performed to detect the expression of Dishevelled‐1. The results showed, that one day after MI, Dishevelled‐1 mRNA but not protein expression was detected in the cells at the border zone of the infarction area; 4 days after MI the expression of Dishevelled‐1 increased exclusively and cytoplasmic Dishevelled‐1 was observed not only at the border zone but also in the infarct area; 7 days after MI, it seems that the expression reached its peak, the positive staining even spread into the endothelial and smooth muscle cells of the newly formed and pre‐existing blood vessels in the infarction area; after that the Dishevelled‐1 expression decreased abruptly and could hardly be detected 28 days after MI. Thus cytoplasmic Dishevelled‐1 may be involved in the controlled proliferation and migration of myofibroblasts and vascular endothelial cells, hence play a role during the wound healing process after MI.
Somatic stem cell research for neural repair: current evidence and emerging perspectives
Authors: Corti Stefania , Locatelli Federica , Papadimitriou Dimitra , Strazzer Sandra , Comi G. P.
Published: May 2007

Recent evidence supports the existence of adult mammalian stem cell subpopulations, particularly within the bone marrow, that may be able to “transdifferentiate” across tissue lineage boundaries, thus offering an accessible source for therapeutic applications even for neural tissue repair. However, the difficulties in reproducing some experimental data, the rarity of the transdifferentiation events and observations that cell fusion may be an alternative explanation argue against the idea of stem cell plasticity. Investigations going beyond descriptive experiments and more mechanicistic approaches may provide a more solid foundation to adult stem cell therapeutic potential.
Etoposide differentially affects bone marrow and dermal derived endothelial cells
Authors: Adams S. W. , Wang Lin , Fortney J. , Gibson Laura F.
Published: May 2007

Chemotherapy alteration of the bone marrow microenvironment has the potential to influence hematopoietic recovery following transplantation. To discern the effect of specific drugs on components of the complex marrow microenvironment,in vitromodels have significant utility. In the current study we sought to determine whether dermal (HEMEC‐1) and marrow derived endothelial cells (BMEC‐1) respond differently to identical chemotherapy exposure. BMEC‐1 cells were consistently more sensitive to etoposide exposure than HMEC‐1 cells, measured as reduced viability. BMEC‐1 also had reduced focal adhesion kinase (FAK) and VCAM‐1 protein expression following chemotherapy, in contrast to dermal derived endothelial cells in which neither protein was influenced dramatically by etoposide. The two endothelial cell lines had markedly different levels of baseline VE‐Cadherin protein, which was modestly altered by treatment. These data indicate that marrow derived endothelial cells have disruption of specific proteins following chemotherapy that may influence their ability to facilitate hematopoietic cell entry or egress from the marrow. In addition, these observations suggest that while BMEC‐1 and HMEC‐1 share a variety of characteristics, they differ significantly in their response to stress and should be incorporated into specific models with this consideration.
Hydrolysis of myelin basic protein by polyclonal catalytic IgGs from the sera of patients with multiple sclerosis
Authors: Polosukhina Darya I. , Kanyshkova Tatyana G. , Doronin Boris M. , Tyshkevich Olga B. , Buneva Valentina N. , Boiko Alexey N. , Gusev Evgenii I. , Favorova Olga O. , Nevinsky Georgy A.
Published: May 2007

Various catalytic antibodies or abzymes have been detected recently in the sera of patients with several autoimmune pathologies, where their presence is most probably associated with autoimmunization. Recently we have shown that DNase, RNase, and polysaccharide‐hydrolyzing activities are associated with IgGs from the sera of patients with multiple sclerosis (MS). Here we present evidence demonstrating that highly purified MS IgGs (but not Igs from the sera of healthy individuals) catalyze specifically hydrolysis of human myelin basic protein (hMBP). In contrast to many known proteases, IgGs do not hydrolyze many other different proteins. Specific inhibitors of acidic and thiol proteases have no remarkable effect on proteolytic activity of IgGs. However, specific inhibitor of serine (PMSF, AEBSF, and benzamidin) and metal‐dependent (EDTA) proteases significantly inhibit activity of proteolytic abzymes. Interestingly, the ratio of serine‐like and metal‐dependent activities of MS IgGs varied very much from patient to patient. The findings speak in favor of the generation by the immune systems of individual MS patients of a variety of polyclonal anti‐MBP IgGs with different catalytic properties.
The ultrastructural aspects of neoplastic myoepithelial cell in pleomorphic adenomas of salivary glands
Authors: Margaritescu C. , Raica M. , Florescu Maria , Simionescu Cristiana , Surpateanu M. , Jaubert F. , Bogdan FI.
Published: May 2007

The purpose of this study has been to establish the major ultrastructural aspects of the myoepithelial cell and the myoepithelial‐like cells proliferated in the pleomorphic adenomas of salivary glands. Thus, twelve benign pleomorphic adenomas of salivary glands have been studied by electron‐microscopy transmission techniques. Our analysis has proved the proliferation of two major cellular populations, one of ductal type and one of myoepithelial type, which tried to reproduce the tubulo‐acinar cytoarchitecture from the normal salivary glands. We have also noticed the key role of the so‐called ‘modified’ myoepithelial cells from the periphery of the proliferating epithelial units in the genesis of the myxoid and chondromyxoid tumoral stromal areas. All these ultrastructural aspects have explained the great histological diversity of these salivary gland neoplasms as well as the key role of the myoepithelial cell in its histogenesis.
Use of an improved zirconyl hematoxylin stain in the diagnosis of Barrett's esophagus
Authors: McNulty Jeannette M. , Kambour Michael J. , Smith Allen A.
Published: May 2007

Barrett's esophagus is a precancerous condition characterized by replacement of the normal stratified squamous epithelium by a simple columnar epithelium with goblet cells that secrete an acidic mucin. As originally formulated, fresh solutions of zirconyl hematoxylin stain goblet cells poorly. An improved formula, quintupling the amount of oxidant, yields zirconyl hematoxylin solutions that stain goblet cells darkly even when fresh. The improved zirconyl hematoxylin can be used in place of alcian blue in the diagnosis of Barrett's esophagus. The ingredients of zirconyl hematoxylin are always readily available and are generally recognized as safe.
Langerhans cell histiocytosis: report of a single organ involvement in a child
Authors: Buza Natalia , Lagarde D. C. , Dash Srikanta , Haque Salima
Published: May 2007

Langerhans cell histiocytosis is a rare disorder characterized by abnormal proliferation of Langerhans cells that can affect various organ systems. The disease usually presents as a unifocal lytic bone lesion and can affect any age group. Less frequently it presents as a disseminated disease with multisystem involvement. Hepatic manifestation in Langerhans cell histiocytosis is relatively rare and usually presents as a part of a disseminated process. We report a case of Langerhans cell histiocytosis involving only the liver in a 9‐years‐old child.
Skeletal muscle tissue engineering
Authors: Bach A. D. , Beier J. P. , Stern‐Staeter J. , Horch R. E.
Published: May 2007

The reconstruction of skeletal muscle tissue either lost by traumatic injury or tumor ablation or functional damage due to myopathies is hampered by the lack of availability of functional substitution of this native tissue. Until now, only few alternatives exist to provide functional restoration of damaged muscle tissues. Loss of muscle mass and their function can surgically managed in part using a variety of muscle transplantation or transposition techniques. These techniques represent a limited degree of success in attempts to restore the normal functioning, however they are not perfect solutions. A new alternative approach to addresssing difficult tissue reconstruction is to engineer new tissues. Although those tissue engineering techniques attempting regeneration of human tissues and organs have recently entered into clinical practice, the engineering of skletal muscle tissue ist still a scientific challenge. This article reviews some of the recent findings resulting from tissue engineering science related to the attempt of creation and regeneration of functional skeletal muscle tissue.
HIF‐1 and p53: communication of transcription factors under hypoxia
Authors: Schmid Tobias , Zhou Jie , Brüne Bernhard
Published: May 2007

Oxygen sensing and reactivity to changes in the concentration of oxygen is a fundamental property of cell physiology. The lack of O2 (hypoxia) is transmitted into many adaptive responses, a process that is largely controlled by a transcription factor known as hypoxia inducible factor‐1 (HIF‐1). More recent reports suggest that besides its traditional regulation via proteasomal degradation other signaling pathways contribute to stability regulation of the HIF‐1α subunit and/or HIF‐1 transactivation. These regulatory circuits allow for the integration of HIF‐1 into scenarios of cell‐survival vs. cell‐death with the rule of the thumb that short‐term mild hypoxia maintains cell viability while prolonged and severe hypoxia provokes cell demise. Cell death pathways are associated with stabilization of the tumor suppressor p53, a response also seen under hypoxic conditions. Here we summarize recent information on accumulation of HIF‐1α and p53 under hypoxia and provide a model to explain the communication between HIF‐1 and p53 under (patho)physiological conditions.
Caspases: potential targets for regulating cell death
Authors: Philchenkov A.
Published: May 2007

While in multicellular organisms all cells inexorably die, there are several different ways provided for the realization of cell death. One of them, apoptosis, represents a universal energy‐dependent and tightly regulated physiologic process of cell death in both normal and pathologic tissues. The execution of apoptosis appears to be uniformly mediated through consecutive activation of the members of a caspase family. This review briefly summarizes current knowledge on the molecular mechanisms of caspase activation and the inhibitory components of caspase cascades. The suitability of caspases as a new potential therapeutic target is discussed next. Particular attention is focused on two broad categories of caspase‐directed compounds: highly specific caspase inhibitors that distinctly block the progress of apoptosis and caspase activators that selectively induce cell death in a variety of in vitro and in vivo systems. These agents promise to be useful clinically, either alone or in combination with more conventional therapeutics.
Dissection of the multiple mechanisms of TNF‐α‐induced apoptosis in liver injury
Authors: Ding Wen‐Xing , Yin Xiao‐Ming
Published: May 2007

Tumor necrosis factor (TNF)‐α‐induced hepatocyte apoptosis is implicated in a wide range of liver diseases including viral hepatitis, alcoholic hepatitis, ischemia/reperfusion liver injury, and fulminant hepatic failure. TNF‐α exerts a variety of effects that are mediated mainly by TNF‐receptor 1 (TNF‐R1) in cell death. The activation of TNF‐R1 leads to the activation of multiple apoptotic pathways involving the activation of the pro‐death Bcl‐2 family proteins, reactive oxygen species, C‐Jun NH2‐terminal kinase, cathepsin B, acidic sphingomyelinase and neutral sphingomyelinase. These pathways are closely interlinked and mainly act on mitochondria, which release the apoptogenic factors and other events, resulting in apoptosis. This article reviews the recent progress in the molecular mechanisms of TNF‐α‐induced apoptosis in hepatocytes, and discusses how these molecular findings are shaping our understanding of the pathogenesis of liver diseases and our strategy to develop novel therapeutics.
Embryonic stem cells: a promising tool for cell replacement therapy
Authors: Doss Michael Xavier , Koehler Christoph I. , Gissel C. , Hescheler Jürgen , Sachinidis Agapios
Published: May 2007

Embryonic stem (ES) cells are revolutionizing the field of developmental biology as a potential tool to understand the molecular mechanisms occurring during the process of differentiation from the embryonic stage to the adult phenotype. ES cells harvested from the inner cell mass (ICM) of the early embryo can proliferate indefinitely in vitro while retaining the ability to differentiate into all somatic cells. Emerging results from mice models with ES cells are promising and raising tremendous hope among the scientific community for the ES‐cell based cell replacement therapy (CRT) of various severe diseases. ES cells could potentially revolutionize medicine by providing an unlimited renewable source of cells capable of replacing or repairing tissues that have been damaged in almost all degenerative diseases such as diabetes, myocardial infarction and Parkinson's disease. This review updates the progress of ES cell research in CRT, discusses about the problems encountered in the practical utility of ES cells in CRT and evaluates how far this approach is successful experimentally.
In search of adult renal stem cells
Authors: Anglani F. , Forino M. , Prete D. Del , Tosetto E. , Torregrossa R. , D'Angelo A.
Published: May 2007

The therapeutic potential of adult stem cells in the treatment of chronic degenerative diseases has becoming increasingly evident over the last few years. Significant attention is currently being paid to the development of novel treatments for acute and chronic kidney diseases too. To date, promising sources of stem cells for renal therapies include adult bone marrow stem cells and the kidney precursors present in the early embryo. Both cells have clearly demonstrated their ability to differentiate into the kidney's specialized structures. Adult renal stem cells have yet to be identified, but the papilla is where the stem cell niche is probably located. Now we need to isolate and characterize the fraction of papillary cells that constitute the putative renal stem cells. Our growing understanding of the cellular and molecular mechanisms behind kidney regeneration and repair processes ‐ together with a knowledge of the embryonic origin of renal cells ‐ should induce us, however, to bear in mind that in the kidney, as in other mesenchymal tissues, the need for a real stem cell compartment might be less important than the phenotypic flexibility of tubular cells. Thus, by displaying their plasticity during kidney maintenance and repair, terminally differentiated cells may well function as multipotent stem cells despite being at a later stage of maturation than adult stem cells. One of the major tasks of Regenerative Medicine will be to disclose the molecular mechanisms underlying renal tubular plasticity and to exploit its biological and therapeutic potential.
Expression of phospholipase D isozymes in scar and viable tissue in congestive heart failure due to myocardial infarction
Authors: Dent Melissa R. , Singal Tushi , Dhalla Naranjan S. , Tappia Paramjit S.
Published: May 2007

The phospholipase D (PLD) associated with the cardiac sarcolemmal (SL) membrane hydrolyses phosphatidylcholine to produce phosphatidic acid, an important phospholipid signaling molecule known to influence cardiac function. The present study was undertaken to examine PLD isozyme mRNA expression, protein contents and activities in congestive heart failure (CHF) subsequent to myocardial infarction (MI). MI was induced in rats by occlusion of the left anterior descending coronary artery. At 8 weeks after the surgical procedure, hemodynamic assessment revealed that these experimental rats were at a moderate stage of CHF. Semi‐quantitative reverse transcriptase‐polymerase chain reaction revealed that PLD1 and PLD2 mRNA amounts were unchanged in viable left ventricular (LV) tissue of the failing heart. Furthermore, this technique demonstrated the presence of PLD1 and PLD2 mRNA in the scar tissue. While SL PLD1 and PLD2 protein contents were elevated in the viable LV tissue of the failing heart, SL PLD1 activity was significantly decreased, whereas SL PLD2 activity was significantly increased. On the other hand, although PLD1 protein was undetectable, PLD2 protein and activity were detected in the scar tissue. Our findings suggest that differential changes in PLD isozymes may contribute to the pathophysiology of CHF and may also be involved in the processes of scar remodeling.