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At least 847 records · Page 47Linked to original sources
PubMed2004

Spatial distribution and temporal onset of NF-kB activation and inducible nitric oxide synthase within pancreatic islets in the pre-diabetic stage of genetic, diabetic-prone BB rats: attenuation by drug intervention decreases inflammatory cell infiltration and incidence of diabetes.

OBJECTIVE AND DESIGN: To document in vivo immunolocalization and activation of nuclear factor-kappaB (NF-kappaB) and inducible nitric oxide synthase (iNOS) expression in prediabetic stages of diabetes mellitus. MATERIAL OR SUBJECTS: Genetic, diabetic-prone or diabetic-resistant BB rats (total = 189). TREATMENT: Various doses of an oral dithiocarbamate derivative, NOX-700, or cyclosporine (2.5 mg/kg) starting at 30 or 60 days of age. METHODS: Immunohistochemistry, electrophoretic mobility shift assays, plasma glucose. RESULTS: NF-kappaB and iNOS was increased in pancreas of hyperglycemic, diabetic-prone rats but not normoglycemic, diabetic-resistant rats. Immunostaining for NF-kappaB and iNOS was largely confined to islets and occurred in diabetic-prone rats prior to overt hyperglycemia. NOX-700 decreased cell infiltration, delayed the onset of disease and decreased the incidence of hyperglycemia to levels achieved by immunosuppressant therapy. NOX-700 also decreased the intensity of immunoreactive NF-kappaB and iNOS within pancreatic islets. CONCLUSIONS: These studies support a role of NF-kB and iNOS in diabetogenesis in vivo.

Animals↗
PubMed2000

Temporal and Spatial Distribution of the nifH Gene of N(2) Fixing Bacteria in Forests and Clearcuts in Western Oregon.

Decomposition of plant litter is a primary mechanism of nutrient recycling and redistribution in most terrestrial ecosystems. Previously we demonstrated by a nested PCR protocol that 20 distinctive nifH (the gene encoding nitrogenase reductase) HaeIII restriction fragment length polymorphism (RFLP) patterns were derived from bulk DNA associated with samples of plant litter and soil collected at one Douglas Fir (DF) forest [33]. Five of the nifH DNA patterns (II-VI) were dominant types in DF litter with characteristic fragments of 237-303 bp length, whereas samples from soil contained primarily seven other patterns 131-188 bp length (IX-XV). Here we report that the 237-303 bp fragments characteristic for forest litter could generally not be detected in plant litter or soil samples collected in clearcuts that adjoin the forest sites. The same fragments (237-303 bp) were also found in the litter at this DF forest site over 16 months and were consistently found in litter at 12 other DF forest or recent (<2 yrs) clearcut sites. However, trace to none of these fragments were detected in 6 clearcut (5-10 yrs) or different forest types (oak, alder) collected over a 200 km east-west direction in western Oregon, USA. Data suggest that the logging practice in DF forests that creates a clearcut removes a unique gene pool of nitrogen-fixing microorganisms. These organisms could potentially contribute more to nitrogen fixation in forest litter than litter from natural or invasive plants that grow in clearcuts [26]. </hea

Journal Article↗
PubMed2002

Quantitative determination of the spatial distribution of pure- and mixed-strain immobilized cells in gel beads by immunofluorescence.

A new method was developed to detect and quantify two strains, Lactococcus lactis subsp. lactis biovar. diacetylactis MD and Bifidobacterium longum ATCC 15707, immobilized separately and co-immobilized in gel beads, using specific polyclonal antibodies and confocal laser-scanning microscopy. The establishment of biomass concentration profiles for each strain was measured during colonization of beads using successive pH-controlled batch fermentations. Growth occurred preferentially in 200- and 300-microm peripheral layers of the beads for L. diacetylactis and B. longum, respectively. Repeated-batch cultures with immobilized cells permitted the production of a mixed culture containing a non-competitive strain of bifidobacteria, as a result of immobilized-cell growth and high cell-release activity from the beads. During co-immobilized fermentations, there were no apparent interactions between the strains.

Bifidobacterium↗
PubMed1997

Spatial distribution of beta-spectrin in normal and dystrophic human skeletal muscle.

Spectrin, a major component of the erythrocyte membrane skeleton, has previously been shown to form a two-dimensional lattice in erythrocytes, and in avian or chicken skeletal muscle. Those results were mainly obtained with antibodies against alpha-spectrin. Using immunofluorescence of semithin cryosections and single muscle fiber preparations, we show here that beta-spectrin forms a costameric network which covers the plasma membrane of human skeletal muscle. These spectrin costameres are correlated with the Z-bands. They are longitudinally connected by fine strands and interrupted by myonuclear lacunae. Under mechanical stretching, the costameres retained their correlation to the Z-bands in normal and dystrophin-deficient muscle, up to the point at which the sarcolemma was disrupted. In stretched muscle, in some regions of the stretched fibers in which the costameres seemed to form double strands, the usually 1:1 correlation of spectrin to the Z-bands changed to a 2:1 relation. In dystrophin-deficient muscle, the costameric scaffold of spectrin in the well-preserved fibers appeared normal, indicating that spectrin can be correctly localized in the absence of dystrophin and that the subcellular spectrin organization does not primarily depend on dystrophin expression. The regular organization and the correlation of spectrin costameres to the Z-bands was notable even in stretched Duchenne muscular dystrophy (DMD) muscle. On the other hand, single teased muscle fibers of DMD muscle showed various degrees of morphological alterations of the costameric network, ranging from a focal disarray to complete loss of costameric organization. Because these findings indicate that the costameric spectrin scaffold undergoes secondary changes during the course of the dystrophic process in dystrophin-deficient muscle, spectrin staining of isolated muscle fibers may also serve as a tool to monitor the effect of gene therapy experiments at the single fiber level.

Blotting, Western↗
PubMed2002

The temporal and spatial distribution of the proliferation associated Ki-67 protein during female and male meiosis.

We used immunolocalization in tissue sections and cytogenetic preparations of female and male gonads to study the distribution of the proliferation marker pKi-67 during meiotic cell cycles of the house mouse, Mus musculus. During male meiosis, pKi-67 was continuously present in nuclei of all stages from the spermatogonium through spermatocytes I and II up to the earliest spermatid stage (early round spermatids) when it appeared to fade out. It was not detected in later spermatid stages or sperm. During female meiosis, pKi-67 was present in prophase I oocytes of fetal ovaries. It was absent in oocytes from newborn mice and most oocytes of primordial follicles from adults. The Ki-67 protein reappeared in oocytes of growing follicles and was continuously present up to metaphase II. Thus, pKi-67 was present in all stages of cell growth and cell division while it was absent from resting oocytes and during the main stages of spermiocytogenesis. Progression through the meiotic cell cycle was associated with extensive intranuclear relocation of pKi-67. In the zygotene and pachytene stages, most of the pKi-67 colocalized with centromeric (centric and pericentric) heterochromatin and adjacent nucleoli; the heterochromatic XY body in male pachytene, however, was free of pKi-67. At early diplotene, pKi-67 was mainly associated with nucleoli. At late diplotene, diakinesis, metaphase I and metaphase II of meiosis, pKi-67 preferentially bound to the perichromosomal layer and was almost absent from the heterochromatic centromeric regions of the chromosomes. After the second division of male meiosis, the protein reappeared at the centromeric heterochromatin and an adjacent region in the earliest spermatid stage and then faded out. The general patterns of pKi-67 distribution were comparable to those in mitotic cell cycles. With respect to the timing, it is interesting to note that relocation from the nucleolus to the perichromosomal layer takes place at the G2/M-phase transition in the mitotic cell cycle but at late diplotene of prophase I in meiosis, suggesting physiological similarity of these stages.

Animals↗
PubMed1999

Spatial distribution of human liver aldehyde dehydrogenase isoenzymes.

To elucidate the pattern of lesions in the liver parenchyma after ethanol ingestion, the quantitative distribution profiles of both the cytosolic and the mitochondrial aldehyde dehydrogenase isoenzyme activities were determined by the use of ultrathin-layer electrophoresis. It was found that in human liver parenchyma, both isoforms of aldehyde dehydrogenase are almost homogeneously represented in the liver acinus. These quantitative data are supported by the results of an improved histochemical technique. Moreover, sex differences were not detected either in activity or in the distribution pattern. Consequently, it can be assumed that it is not the activity of total aldehyde dehydrogenase or its isoforms which is responsible for the higher susceptibility of the perivenous zone to alcohol-dependent damage.

Aldehyde Dehydrogenase↗
PubMed1997

Separating spatially distributed response to stimulation from background. I. Optical imaging.

We consider the problem of estimating a small stimulus-induced response to stimulation that is masked by a fluctuating background when measurements of the background in the absence of stimulation are available, as is common in optical imaging of the cortex and in many other experimental situations. Two related methods based on the Karhunen-Loève procedure are discussed. One seeks the function, an indicator function, that is most parallel to the response data and most orthogonal to the background data. The second removes the subspace spanned by the background from the response. Numerical investigations on simulated optical imaging data show that the first method is generally superior. Connections between the two methods and techniques for assessing the quality of the result are discussed.

Artifacts↗
PubMed2003

Nutrient translocation in the xylem of poplar--diurnal variations and spatial distribution along the shoot axis.

This investigation shows diurnal variations in the xylem sap composition of poplar (Populus tremula x P. alba). All major macronutrients reached a maximum concentration in the first half of the light period and decreased to the middle of the night. The relative abundance of the nutrients did not change during the day. The sap flow, which responded very fast to the environmental changes (2.2-fold increase within 10-20 min of illumination), reached a maximum value in the second half of the light period. Transpiration (and photosynthesis) was constant throughout the light phase. The calculated translocation rates displayed a maximum in the first half of the light period and therefore did not fit the time course of sap flow. During the night, translocation rates were 63-69% lower than the maximum. The regulation of nutrient translocation is discussed taking the active xylem loading into account. The axial distribution located the nitrate assimilation in younger leaves and storage of nitrate (and other macronutrients) in older leaves. Nitrate and potassium concentrations in the xylem sap did not change along the plant axis. However, the sap flow was greater in younger shoot sections than in older sections. We assume that the greater demand for nitrate in the younger shoot section was satisfied via an increased volume flow rather an increased nitrate concentration.

Biological Transport↗
PubMed1999

Duct changes and K-ras mutations in the disease-free pancreas: analysis of type, age relation and spatial distribution.

Recent molecular studies have suggested that hyperplastic duct lesions of the pancreas are potential precursors of pancreatic ductal carcinoma. This study examines the type, distribution, age-related incidence and K-ras codon 12 mutation rate of duct lesions in the normal pancreas. Postmortem pancreases from 140 patients were screened for the presence of mucinous cell hypertrophy (MHT), ductal papillary hyperplasia (DPH), adenomatoid ductal hyperplasia (ADH), and squamous metaplasia (SQM). Microdissected cell samples were analyzed for K-ras codon 12 mutations by polymerase chain reaction amplification of exon 1 of the K-ras gene, combined with constant denaturing gel electrophoresis, and analyzed by sequencing. Of the 140 specimens 114 showed duct lesions. The lesions were evenly distributed throughout the pancreas. They were more common beyond the age of 40. MHT was present in 68%, DPH in 36%, ADH in 40%, and SQM in 36% of the cases. K-ras mutations were found in 19 samples from 15 out of 79 pancreases (18%), including all types of duct lesions and a variant of ADH with dense stroma. 67% of the K-ras-positive specimens showed the transition GGT to GAT (8) or GTT (5). Hyperplastic/metaplastic duct changes of the pancreas increase with age, but their distribution pattern in the pancreas differs from that of ductal carcinomas.

Adolescent↗
PubMed1997

M cells in the rabbit palatine tonsil: the distribution, spatial arrangement and membrane subdomains as defined by confocal lectin histochemistry.

The crypt epithelium of the palatine tonsil contains M cells that play an important role in the uptake of luminal antigens to initiate immune responses. To study the close interaction of M cells, squamous epithelial cells and lymphocytes we used confocal laser scanning microscopy and the lectin from Ulex europaeus (UEA-I), which selectively labels rabbit tonsillar M cells. Confocal serial sections and synthetic section planes showed that the M cells comprise up to 35% of the epithelial cells in the tonsil crypt and completely engulf clusters of two to eight lymphocytes with their apical cytoplasm. These lymphocytes lie in a pocket of the M cell's basolateral membrane that invaginates from one of the lateral aspects and forms a tunnel-like opening. Therefore, the tonsillar M cells closely resemble the M cells of the small and large intestines in their spatial structure, and likewise maintain an intraepithelial compartment for the interaction of lymphocytes, macrophages and antigens. The UEA-I bound intensely to the apical membrane of the M cells and to transcytotic vesicles in the apical cytoplasm. The pocket membrane bound the UEA-I more avidly than the remaining basolateral membrane, suggesting that the basolateral membrane of M cells is subdivided into membrane domains with different compositions of glycoconjugates.

Animals↗
PubMed1997

The spatial distribution of human immunoglobulin genes within the nucleus: evidence for gene topography independent of cell type and transcriptional activity.

The three-dimensional positioning of immunoglobulin (Ig) genes within the nucleus of human cells was investigated using in situ hybridization and confocal microscopy. The visualization of heavy and light chain genes in B-lymphoid cells showed that the three Ig genes are differentially and nonrandomly distributed in different nuclear subvolumes: the kappa genes were found to be preferentially confined to an outer nuclear volume, whereas the gamma and lambda genes consistently occupied more central positions within the nucleus, the lambda genes being more interior when compared with the gamma genes. The data further show that these overall topographical distributions are independent of gene transcriptional activity and are conserved in different cell types. Although subtle gene movements within those defined topographical regions cannot be excluded by this study, the results indicate that tissue specificity of gene expression is not accompanied by drastic changes in gene nuclear topography, rather suggesting that gene organization within the nucleus may be primarily dependent on structural constraints imposed on the respective chromosomes.

B-Lymphocytes↗