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At least 1,009 records · Page 56Linked to original sources
PubMed1986

Man versus beast: pharmacokinetic scaling in mammals.

Land mammals range in size from the 3-g shrew to the 3000-kg elephant. Despite this 10(6) range in weight, most land mammals have similar anatomy, physiology, biochemistry, and cellular structure. This similarity has allowed interspecies scaling of physiologic properties such as heart rate, blood flow, blood volume, organ size, and longevity. The equation that is the basis for scaling physiologic properties among mammals is the power equation Y = aWb, where Y is the physiologic variable of interest, W is body weight, and log a is the y-intercept and b is the slope obtained from the plot of log Y versus log W. Animals commonly used in preclinical drug studies (i.e., mice, rats, rabbits, monkeys, and dogs) do not eliminate drugs at the same rate that humans eliminate drugs; small mammals usually eliminate drugs faster than large mammals. Since drug elimination is intimately associated with physiologic properties that are well described among species, it seems reasonable to surmise that drug elimination can be scaled among mammals. Analysis of drug pharmacokinetics in numerous species demonstrates that drug elimination among species is predictable and, in general, obeys the power equation Y = aWb. Early papers on interspecies pharmacokinetic scaling normalized the x- and y-axes to illustrate the superimpossibility of pharmacokinetic curves from different species. More recently, the x- and y-axes have been left in the common units of concentration and time, and individual pharmacokinetic variables have been adjusted to predict pharmacokinetic profiles in an untested species, usually humans.

Administration, Oral↗
PubMed2001

Proteome analysis of rat spermatogonia: reinvestigation of stathmin spatio-temporal expression within the testis.

Stathmin is a protein known to be involved in various cell processes including cell proliferation and differentiation. It has already been described in the testis but its recent identification using a proteomic approach in mitotic spermatogenetic stem cells named spermatogonia (Guillaume et al., 2000) has lead us to reinvestigate its expression within the testis. Stathmin and its mRNAs were studied in isolated cells by Western and Northern blots and in situ using immunohistochemistry. We demonstrated that stathmin is indeed expressed in spermatogonia, and that it is also intensively expressed in the meiotic spermatocytes and in the first generations of spermatids. Furthermore, we showed aggregations of the protein in the cytoplasm of the later generations of spermatids preceding its elimination at the time of spermiation. Our Northern blots reveal the presence of two stathmin transcripts of 1.1 and 3.2 kb within the testis from the fetal stage onwards, in spermatogonia, spermatocytes, and spermatids. However, the 3.2 kb RNA transcript was barely detectable in the spermatids. Stathmin expression is known to be associated with microtubule dynamics. Therefore, its expression in the germ line is most probably related to the extremely complex structural cellular rearrangements occurring in germ cells during spermatogenesis. However, the exact role of stathmin and the reason of the existence of two transcripts in the male germ lineage awaits further investigation.

Animals↗
PubMed2006

Site-specific interactions of neurotrophin-3 and fibroblast growth factor (FGF2) in the embryonic development of the mouse cochlear nucleus.

Neurotrophins and FGF2 contribute to formation of the cochlea, but their roles in cochlear nucleus development are unknown. The effects of these factors may differ in the cochlea and cochlear nucleus, which may influence each other's development. It is important to analyze the effects of these factors on cellular structures at well-defined steps in the normal morphogenetic sequence. The present study used immunohistochemistry to localize factors in situ and to test hypotheses about their roles in an in vitro model. Specific antibody staining revealed that TrkC, the NT3 receptor, is present in neural precursors prior to embryonic day E11 until after birth. NT3 appeared in precursor cells during migration (E13-E15) and disappeared at birth. TrkC and NT3 occurred in the same structures, including growing axons, terminals, and their synaptic targets. Thus, NT3 tracks the migration routes and the morphogenetic sequences within a window defined by TrkC. In vitro, the cochlear nucleus anlage was explanted from E11 embryos. Cultures were divided into groups fed with defined medium, with or without FGF2, BDNF, and NT3 supplements, alone or in combinations, for 7 days. When neuroblasts migrated and differentiated, immunostaining was used for locating NT3 and TrkC in the morphogenetic sequence, bromodeoxyuridine for proliferation, and synaptic vesicle protein for synaptogenesis. By time-lapse imaging and quantitative measures, the results support the hypothesis that FGF2 promotes proliferation and migration. NT3 interacts with FGF2 and BDNF to promote neurite outgrowth, fasciculation, and synapse formation. Factors and receptors localize to the structural sites undergoing critical changes.

Animals↗
PubMed1993

Effects of development and altered gravity conditions on cytochrome oxidase activity in a vestibular nucleus of the larval teleost brain: a quantitative electronmicroscopical study.

The mitochondrial enzyme, cytochrome oxidase, was localized cytochemically in the nucleus magnocellularis, a primary relay nucleus of vestibular information within the area octavolateralis in the fish brain. Larvae of the cichlid fish Oreochromis mossambicus were analyzed at different developmental stages (4, 10, and 35 days post-hatching) and after long-term exposure (8 days) to increased gravity (2-4 g). Quantification of highly reactive, moderately reactive, and nonreactive mitochondria reveals differences in the cytochrome oxidase activity of various cellular structures, for example, perikarya of neurons, presynaptic terminals, and myelinated and nonmyelinated cell profiles. Cytochrome oxidase activity in the mitochondria of neuronal perikarya increases during development which parallels the differentiation of the area octavolateralis. This possibly reflects the increasing energy demand during maturation and innervation of the magnocellular nucleus. Hyper-g-exposure of the larvae for 8 days (centrifuge) caused a further augmentation of cytochrome oxidase activity in the perikarya within the nucleus magnocellularis. This may reflect an increased oxidative metabolism resulting from the need for compensation of altered inputs from gravity-sensitive epithelia in the inner ear. Another possibility is that acceleration within a centrifuge causes physiological stress for the animals and, therefore, influences the cytochrome oxidase activity in neurons.

Animals↗
PubMed2004

The keratin cytoskeleton in liver diseases.

The keratin intermediate filament (IF) cytoskeleton of hepatocytes has continuously gained medical relevance over the last two decades. Originally it was mainly recognized as a differentiation marker for diagnostic purposes in pathology. However, keratin IFs were soon identified as major cellular structures to be affected in a variety of chronic liver diseases, such as alcoholic and non-alcoholic steatohepatitis (ASH, NASH), copper toxicosis, and cholestasis. Based on observations in keratin gene knock-out mice, the insight into the functional role of keratins was extended from a mere structural role providing mechanical stability to hepatocytes, to an additional role as target and modulator of toxic stress and apoptosis. The functional relevance of keratins in human diseases has recently been underlined by the identification of mutations in keratin genes in patients with liver cirrhosis.

Biliary Tract↗
PubMed1995

Non-isotopic in situ hybridization at the ultrastructural level.

Non-isotopic in situ hybridization techniques are becoming increasingly widely used at the ultrastructural level, permitting rapid localization of nucleic acid targets with a high degree of resolution. Technical considerations dictate that the great specificity of the method cannot be matched by a similar degree of sensitivity; the value of non-isotopic ultrastructural in situ hybridization lies in its unique ability to localize nucleic acid targets in relation to submicroscopic cellular structures. This article presents an overview of non-isotopic ultrastructural hybridization methods and applications.

Animals↗
PubMed2003

Improved proteome analysis of Saccharomyces cerevisiae mitochondria by free-flow electrophoresis.

The analysis of complex cellular proteomes by means of two-dimensional gel electrophoresis (2-DE) is significantly limited by the power of resolution of this technique. Although subcellular fractionation can be a fundamental first step to increase resolution, it frequently leads to preparations contaminated with other cellular structures. Here, we chose mitochondria of Saccharomyces cerevisiae to demonstrate that an integrated zone-electrophoretic purification step (ZE), with a free-flow electrophoresis device (FFE), can assist in overcoming this problem, while significantly improving their degree of purity. Whereas mitochondrial preparations isolated by means of differential centrifugation include a considerable degree of non-mitochondrial proteins (16%), this contamination could be effectually removed by the inclusion of a ZE-FFE purification step (2%). This higher degree of purity led to the identification of many more proteins from ZE-FFE purified mitochondrial protein extracts (n = 129), compared to mitochondrial protein extracts isolated by differential centrifugation (n = 80). Moreover, a marked decrease of degraded proteins was found in the ZE-FFE purified mitochondrial protein extracts. It is noteworthy that even at a low 2-DE resolution level, a four-fold higher number (17 versus 4) of presumably low abundance proteins could be identified in the ZE-FFE purified mitochondrial protein extracts. Therefore these results represent a feasible approach for an in-depth proteome analysis of mitochondria and possibly other organelles.

Electrophoresis↗
PubMed2005

Proteome modifications of blue mussel (Mytilus edulis L.) gills as an effect of water pollution.

The discharge of chemicals such as oil associated or not with derived products constitutes a real threat for the environment. We report here the differential expression of the blue mussel (Mytilus edulis) gill proteins corresponding to two contaminated environmental conditions: crude oil and offshore produced water. In order to evaluate and understand contaminants, effects and adaptive response of these organisms, we identified proteins using MS. The latter can be grouped into three main classes: proteins involved in the cellular structure, in metabolism, and in defence proteins.

Animals↗
PubMed2006

Proteomic characterization of the cytotoxic mechanism of gold (III) porphyrin 1a, a potential anticancer drug.

There has been increasing interest in the potential applications of gold (III) complexes as anticancer drugs with higher cytotoxicity and fewer side effects than existing metal anticancer drugs. Our previous findings demonstrated that gold (III) porphyrin 1a preferentially induced apoptosis in a cancer cell line (SUNE1). In this study, we identified differentially expressed proteins related to the drug's cytotoxic action by comparing the protein alterations induced by gold (III) porphyrin 1a and cisplatin treatments. Several clusters of altered proteins were identified, including cellular structure and stress-related chaperone proteins, proteins involved in reactive oxygen species and enzyme proteins, translation factors, proteins that mediate cell proliferation or differentiation, and proteins participating in the internal degradation systems. Our results indicated that multiple factors leading to apoptosis were involved in drug cytotoxicity in SUNE1 cells. The balance between pro-apoptotic and anti-apoptotic signals determined the final fate of cancer cells.

Antineoplastic Agents↗
PubMed2006

Proteome analysis of multidrug resistance in vincristine-resistant human gastric cancer cell line SGC7901/VCR.

In order to elucidate the mechanisms of multidrug resistance (MDR) of vincristine-resistant human gastric carcinoma cell line SGC7901/VCR, 2-DE was used to separate the total proteins of SGC7901/VCR and its parental cell line SGC7901. PDQuest software was applied to analyze 2-DE images, and the differential protein spots were identified by both MALDI-TOF-MS and ESI-Q-TOF-MS. Then the differential expressional levels of partially identified proteins were determined by Western blot analysis and real-time RT-PCR. Furthermore, the association of heat shock protein (HSP27), one of the highly expressed proteins in sgc7901/vcr, with MDR was analyzed using antisense inhibition of HSP27. In this study, the well-resolved, reproducible 2-DE patterns of SGC7901/VCR and SGC7901 were established, and yielded about 1100 protein-spots each. All the 24 differential proteins between the two cell lines were identified, and the differential expression levels of the partial proteins were confirmed. The suppression of HSP27 expression by HSP27 antisense oligonucleotides could enhance vincristine chemosensitivity in sgc7901/vcr and induce the cells to exhibit apoptotic morphological features after vincristine treatment. The differentially expressed proteins could be divided into six groups based on their functions: calcium-binding proteins, chaperones, proteins involved in drug detoxification or repair of DNA damage, metabolic enzymes, proteins related to cellular structure, and proteins relative to signal transduction, some of which may contribute to MDR of human gastric carcinoma cell line SGC7901/VCR. These data will be valuable for further study of the mechanisms of MDR in human gastric cancer.

Amino Acid Sequence↗
PubMed2005

Target identification of the novel antiobesity agent tungstate in adipose tissue from obese rats.

Adipose tissue plays an active role in the development of obesity, and thus characterization of the molecular changes related to obesity in this tissue is a priority. Recently, we identified tungstate as a potent body weight reducing agent in obese animals, adipose tissue being one of the targets of its action. In this study a proteomics approach combining 2-DE and MS was used to identify proteins associated with obesity and targets of tungstate in white adipose tissue. Twenty-nine proteins were found differentially expressed between lean and diet-induced obese rats. Expression changes in transferrin, vimentin, vinculin, peroxiredoxins, Rho-GTP dissociation inhibitor, grifin, guanine deaminase and 3-phosphoglycerate dehydrogenase were associated here for the first time with obesity. Furthermore, tungstate treatment of obese rats reverted expression changes of 70% of the proteins modulated by obesity and another ten proteins were regulated by tungstate independently of the body weight reduction. The results suggest that the tungstate antiobesity effect can be mediated by the modulation of cellular structure, metabolism, redox state and signalling processes in adipose tissue. These findings open new avenues for the study of the aetiology of obesity and its treatment.

Adipose Tissue↗
PubMed1996

Quantitative three-dimensional confocal imaging of the cornea in situ and in vivo: system design and calibration.

A new depth encoding system (DES) is presented, which makes it possible to calculate, display, and record the z-axis position continuously during in vivo imaging using tandem scanning confocal microscopy (TSCM). In order to verify the accuracy of the DES for calculating the position of the focal plane in the cornea both in vitro and in vivo, we compared TSCM measurements of corneal thickness to measurements made using an ultrasonic pachymeter (UP, a standard clinical instrument) in both enucleated rabbit, cat, and human eyes (n = 15), and in both human patients (n = 7). Very close agreement was found between the UP and TSCM measurements in enucleated eyes; the mean percent difference was 0.50 +/- 2.58% (mean +/- SD, not significant). A significant correlation (R = 0.995, n = 15, p < 0.01) was found between UP and TSCM measurements. These results verify that the theoretical equation for calculating focal depth provided by the TSCM manufacturer is accurate for corneal imaging. Similarly, close agreement was found between the in vivo UP and TSCM measurements; the mean percent differences was 1.67 +/- 1.38% (not significant), confirming that z-axis drift can be minimized with proper applanation of the objective. These results confirm the accuracy of the DES for imaging of the cornea both ex vivo and in vivo. This system should be of great utility for applications where quantitation of the three-dimensional location of cellular structures is needed.

Adult↗
PubMed1996

In vivo confocal microscopy of human skin: a new design for cosmetology and dermatology.

In-depth exploration of cellular structures in living human skin in situ is possible with the tandem scanning microscope (TSM). However, the rigid design of the microscope limited observations to the arms, hands, and fingers. A mobile version allowing the investigation of any parts of the body has been designed. The head containing the Nipkow disk and the optical path were the only part saved from the original TSM. This prototype can be used to observe, in real time, the different skin structures down to a depth of 200 microns and to measure the thickness of the different layers with micron precision level. The hydration of the stratum corneum (SC) could be assessed. For example, lengthy immersion of the hand in water led to an increase in SC thickness without affecting that of the living epidermis. Occlusive patch tests also showed that water and, even more so. propylene glycol, led to transient swelling of the SC. In dermatology, the example of psoriasis illustrated the value of the TSM for describing, measuring, and assessing pathologic skin changes. The availability of this noninvasive method for observing changes with time in a given skin site should prove useful for monitoring treatment efficacy. This tool opens up new insight for the investigation of cutaneous pathophysiology.

Cosmetics↗
PubMed1997

Lack of hemodynamic forces triggers apoptosis in vascular endothelial cells.

The endothelial cells (EC) of the vascular system are regularly exposed to a range of hemodynamic forces with great impact on cellular structures and functions. A shear-stress-dependent modulation has been reported for various endothelial functions, and first attempts were made to characterize the nature of the shear-stress-sensitive receptor. Apoptosis has been induced in cultures of vascular EC upon application of various stimuli characteristic of traumatic or pathogenic events. However, no link between apoptosis and mechanical stimulation has been reported so far-neither for vascular EC nor for other types of cells. Here we show that the lack of hemodynamic forces triggers apoptosis in endothelial cells, hinting at mechanical forces as essential stimuli for the maintenance of blood vessels.

Apoptosis↗
PubMed1999

Protein expression in liposomes.

Compartmentalization is one of the key steps in the evolution of cellular structures and, so far, only few attempts have been made to model this kind of "compartmentalized chemistry" using liposomes. The present work shows that even such complex reactions as the ribosomal synthesis of polypeptides can be carried out in liposomes. A method is described for incorporating into 1-palmitoyl-2-oleoyl-sn-3-phosphocholine (POPC) liposomes the ribosomal complex together with the other components necessary for protein expression. Synthesis of poly(Phe) in the liposomes is monitored by trichloroacetic acid of the (14)C-labelled products. Control experiments carried out in the absence of one of the ribosomal subunits show by contrast no significant polypeptide expression. This methodology opens up the possibility of using liposomes as minimal cell bioreactors with growing degree of synthetic complexity, which may be relevant for the field of origin of life as well as for biotechnological applications.

Animals↗
PubMed1993

Cytochemical analysis of the content of chicken thrombocytes vacuoles.

The content of the large vacuoles present in chicken thrombocytes was analyzed by the use of cytochemical techniques which indicated the presence of basic proteins, unsaturated fatty acids, sugars rich in viccinal hydroxyl groups, linked to proteins or lipids and acid phosphatase. These substances perform one of the most conspicuous functions of these cells, which is phagocytosis. In addition, thrombocytes are committed to hemostasis. Both functions make these cells similar to human platelets, even though having different origins and morphologic characteristics. The large vacuoles described are connected to the open canalicular system (OCS) and together with other cellular structures they contribute to the endocytic system.

Acid Phosphatase↗
PubMed2001

Intercellular exchange of class II MHC complexes: ultrastructural localization and functional presentation of adsorbed I-A/peptide complexes.

Activated rat T cells, like human T cells, synthesize class II MHC glycoproteins (MHCII) and absorb MHCII from neighboring T cells. This study focused on interactions of myelin basic protein (MBP)-specific T cells that either synthesized MHCII or absorbed MHCII during activation to assess cellular structures associated with presentation of functional MHCII/peptide complexes. Synthesis of MHCII by CD4(+)TCR(+) T cells involved I-A(+) multivesicular MHC class II-like compartments (MIIC), release of MHCII(+) vesicles, and expression of MHCII on a dendritic arborization. T-cell-mediated adsorption of MHCII was a saturable process that required close cell proximity, actin polymerization, and a permissive temperature. Adsorbed MHCII existed on vesicles that were intimately associated with the responder cell membrane. T cells bearing adsorbed vesicular MHCII presented antigen and were specifically lysed by CD4(+) T cell responders, but when labeled with anti-MHCII antibody were not susceptible to complement-mediated lysis. In summary, this study reveals vesicular compartments associated with synthesis and intercellular exchange of functional MHCII/peptide complexes.

Animals↗
PubMed1993

Comparative effects of cryosolvents on tubulin association, thermal stability, and binding of microtubule-associated proteins.

Organic cryosolvents essential for cryopreservation of living cells have a colligative effect on water properties, but also affect cellular structures such as the membrane, actin, or tubulin cytoskeleton. The effects of cryosolvents on actin and its binding proteins are starting to be well investigated. In parallel, tubulin assembly characteristics were investigated comparatively, with 0-30% 1,2-propanediol, dimethyl sulfoxide, or glycerol, and with or without microtubule-associated proteins, at 37 or 4 degrees C. Tubulin association was monitored by spectrometry and sedimentation, providing the concentration in free protein, cold-depolymerizable microtubules, and cold-resistant associations. At 37 degrees C, 1,2-propanediol and dimethyl sulfoxide induce a similar association level and cold stability of the assemblies. Glycerol yields a lower level of tubulin association. Cold stability of the assemblies requires the presence of solvent, the amount of which is modulated by microtubule-associated proteins (MAPs): 15% 1,2-propanediol or dimethyl sulfoxide, decreasing down to 10% with MAPs, or 10% glycerol with MAPs only. At 4 degrees C, some cold-stable association is promoted by 1,2-propanediol or dimethyl sulfoxide above 10-15%, in the presence or absence of MAPs, but not with glycerol. In addition, protein content of the various fractions obtained with MAPs and 30% solvent was examined by densitometry of electrophoresis gels. Cold-labile associations obtained at 37 degrees C with 1,2-propanediol or dimethyl sulfoxide are lacking in tubulin and enriched in tau proteins relative to control or glycerol. Associations formed at 37 degrees C and stable to subsequent cold treatment, or at 4 degrees C, regardless of the solvent, present a large tubulin content, as well as few tau proteins and high-molecular-weight MAPs.

Animals↗