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At least 757 records · Page 42Linked to original sources
PubMed1999

Topographical localization of lipofuscin pigment in the brain of the aged fat-tailed dwarf lemur (Cheirogaleus medius) and grey lesser mouse lemur (Microcebus murinus): comparison to iron localization.

The present study was undertaken to explore the distribution of lipofuscin in the brain of cheirogaleids by autofluorescence and compare it to other studies of iron distribution. Aged dwarf (Cheirogaleus medius) and mouse (Microcebus murinus) lemurs provide a reliable model for the study of normal and pathological cerebral aging. Accumulation of lipofuscin, an age pigment derived by lipid peroxidation, constitutes the most reliable cytological change correlated with neuronal aging. Brain sections of four aged (8-15 year old) and 3 young (2-3 year old) animals were examined. Lipofuscin accumulation was observed in the aged animals but not in the young ones. Affected regions include the hippocampus (granular and pyramidal cells), where no iron accumulation was observed, the olfactory nucleus and the olfactory bulb (mitral cells), the basal forebrain, the hypothalamus, the cerebellum (Purkinje cells), the neocortex (essentially in the pyramidal cells), and the brainstem. Even though iron is known to catalyse lipid oxidation, our data indicate that iron deposits and lipofuscin accumulation are not coincident. Different biochemical and morphological cellular compartments might be involved in iron and lipofuscin deposition. The nonuniform distribution of lipofuscin indicates that brain structures are not equally sensitive to the factors causing lipofuscin accumulation. The small size, the rapid maturity, and the relatively short life expectancy of the cheirogaleids make them a good model system in which to investigate the mechanisms of lipofuscinogenesis in primates.

Animals↗
PubMed1988

Evidence for independent metabolism and cell surface localization of cell surface localization of cellular proteoglycans and glycosaminoglycan free chains.

The synthesis and turnover of metabolically labeled proteoglycans from medium, cell layer, and substratum-associated compartments were characterized in four cell lines of fibroblastic origin, including a fibrosarcoma line, and in the murine melanoma cell type, B16.F10. Substantial differences were apparent between the various cell types with regard to quantities, hydrodynamic sizes, and compartmentalization of labeled product. Such variations were greater between the different cell lines than between separately labeled cultures of the same cell type. Greater than 85% of cell-associated proteoglycans were accessible to glycosaminoglycan-degrading enzymes added to the medium of monolayer cultures, demonstrating their principal location to be external to the cell membrane. Apparent glycosaminoglycan free chains, determined by a lack of change in hydrodynamic size following alkaline elimination, were among the products from each cell line and were similarly found to be in a principally pericellular location. Results from label-chase studies demonstrated apparent independent kinetics for proteoglycans and glycosaminoglycan free chains, with little conclusive evidence for precursor-product relationships. Also, their processing by the cells was different, since the proteoglycans were shed largely unchanged into the medium for the three cell lines evaluated, whereas the free chains were not recoverable from the medium in significant amounts. The latter observation suggests the internalization of cell surface-associated free chains and their depolymerization at an intracellular site. The results, which indicate that the content, cellular disposition, and turnover of proteoglycans are quite variable between the cell lines studied, may reflect fundamental cell type-specific specialization in the metabolism of these complex substances. Furthermore, the data raise the interesting possibility that glycosaminoglycan free chains may have biological functions at the cellular level, independent of proteoglycans.

Animals↗
PubMed1979

Chronic hematuria and localized bladder damage following combined cyclophosphamide and local radiotherapy.

A 13-year-old white male had Ewing sarcoma of the right pubic and ischial bones. Initial therapy consisted of 5,400 rads in seven weeks to the right side of the pelvis and 14 intravenous injections of cyclophosphamide (Cytoxan, CTX) at 500 mg/m2; BCNU and Adriamycin maintenance therapy continued for a total of two years. He has now been disease-free for five years. Three months following the completion of the right pelvic radiotherapy (RT), while on intravenous CTX, severe hematuria appeared, which subsided, but at present he has continuous microscopic hematuria, as well as periodic episodes of gross hematuria. Serial cystocopies initially revealed thickening and hemorrhagic and edematous changes on the right (irradiated) side of the bladder, and recent multiple telangiectatic patches have been demonstrated as a late "healing" phase. This case demonstrates the additive toxicity to the bladder of CTX and RT, illustrating that the hemorrhagic cystitis can be extremely protracted lasting five years.

Adolescent↗
PubMed1979

Simultaneous localization of steroid and peptide hormones in rat pituitary by combined thaw-mount autoradiography and immunohistochemistry: localization of dihydrotestosterone in gonadotropes, thyrotropes and pituicytes.

The immunocharacteristics of androgen target cells in the anterior pituitary of male rats are assessed by a combined thaw-mount autoradiography and immunoperoxidase staining method permitting the simultaneous identification of steroid-hormone target cells and protein or polypeptide hormone-producing cells in the same preparation. After injection of 3H-dihydrotestosterone, nuclear concentration of radioactivity is observed in cells of the anterior lobe, in "ectopic" cells in the intermediate and posterior lobes as well as in certain pituicytes. The radioactively labeled cells in the anterior lobe are identified immuno-histochemically as gonadotropes and thyrotropes with the use of antiserum to ovine LH or its subunit beta-LH and bovine beta-TSH. The results suggest genomic effects of androgen on gonadotropes and thyrotropes as well as pituicytes.

Animals↗
PubMed1979

Chromosome movement and spindle birefringence in locally heated cells: interaction versus local control.

A microheater was used to produce a temperature gradient within the mitotic spindle of living cells. The slope of the temperature gradient was estimated from thermal conductivity calculations and confirmed by measurements of spindle birefringence and by experiments on striated muscle. When the microheater was placed at one spindle pole or at one group of kinetochores, the gradient was steep enough to cause a large difference in birefringence between the two half-spindles, but the velocity of chromosome movement in anaphase was nearly the same in the warmer and cooler half-spindles. When the heater was shifted from the pole toward the interzone, the average velocity of chromosome movement increased approximately two-fold but was, again, nearly uniform in the two half-spindles. The rate of spindle elongation was especially sensitive to the site of heating, increasing ten-fold when the heater was shifted from the pole to the interzone. Regardless of heater position, the rate of chromosome movement was determined largely by the temperature of the coolest spindle region--chromosomes in the warmer half-spindle moved more slowly than expected from estimates of the temperature in that region. Since the microheater produces a substantial temperature gradient within the spindle, the near uniformity of chromosome velocity in both half-spindles must be due to some biological property of the spindle. Two very different explanations for the results are considered the most likely. According to one explanation, the near uniformity of velocity in both half-spindles is determined by the structure of the interpolar spindle, while changes in velocity involve force producers located both in the half-spindles and in the interzone. On the other explanation, the velocity is nearly the same in both half-spindles because the force producers are located exclusively in the interzone (Margolis et al., 1978).

Anaphase↗
PubMed1993

Localization of NaPi-1, a Na-Pi cotransporter, in rabbit kidney proximal tubules. I. mRNA localization by reverse transcription/polymerase chain reaction.

We have recently isolated from a rabbit cortex cDNA library a cDNA clone (NaPi-1), which, after in vitro transcription (cRNA) and injection into Xenopus laevis oocytes, expresses Na-dependent Pi uptake [Werner A, et al. (1991) Proc Natl Acad Sci USA 88:9608-9612]. The aim of the present work was to study the nephron location of the NaPi-1-related mRNA(s) by combining nephron microdissection procedures, reverse transcription (RT) and amplification of the resultant cDNA by the polymerase chain reaction (PCR). RT-PCR using NaPi-1-specific primers (different combinations) and either total kidney cortex RNA or microdissected proximal tubule segments resulted in two PCR products, both of approximately the expected length (but differing by about 30 base pairs). Restriction-enzyme analysis and nucleotide sequencing confirmed that both PCR products are related to NaPi-1 and that the "longer" PCR product has an insert of 26 base pairs containing an AluI restriction site. Nephron microdissection documents expression of NaPi-1-related mRNA(s) in superficial and deep proximal tubules (S1, S2 and S3 segments) and their absence in glomeruli, thin descending limb and thick ascending limbs of Henle's loop, distal convoluted tubules and cortical and inner medullary collecting ducts. These experiments suggest a "microheterogeneity" of NaPi-1-related mRNA(s) (which is not detected in Northern blot analysis) and proximal tubular expression of NaPi-1.

Animals↗
PubMed1995

Immunoelectron microscopical localization of a circulating antigen in the excretory system of Schistosoma mansoni. Ultrastructural localization studies of the excretory system of S. mansoni.

In this study the excretory system of Schistosoma mansoni was ultrastructurally examined with a recently described monoclonal antibody (mAb) against a circulating antigen. In previous studies this mAb was found to have affinity for the excretory system. Strong immunoreactivity was found on the flagella of the flame cells and of the collecting ducts throughout the worm. The eggshell and the space between the miracidium and the eggshell showed strong reactivity with a declining gradient towards the exterior, suggesting a secretion process. In cercariae, immunoreactivity was restricted to the tegument, whereas in schistosomula the labeling pattern resembled that of the adult worm, demonstrating positive reactivity of the flame cells and no immunostaining of the tegument. This stage-dependent differential expression of different antigens in the excretory system and in the tegument could suggest a maturation process of the excretory system.

Animals↗
PubMed1992

Calcium localization in the shell-forming tissue of the freshwater snail, Biomphalaria glabrata: a comparative study of various methods for localizing calcium.

The routes calcium might take across the mantle to the shell have been investigated with various electron-microscopical techniques in the freshwater snail Biomphalaria glabrata (Planorbidae, Basommatophora). In chemically-fixed tissue, calcium was precipitated with a tannic acid-antimonate technique in predominantly the intercellular spaces of the outer mantle epithelium and the interstitium below it. Some vacuoles of the outer mantle epithelium and one type of mucus cell in the inner mantle epithelium also contained precipitate. The presence of calcium in the precipitates was proved by electron energy loss spectroscopy combined with electron spectroscopic imaging. Incubation with lead acetate and uranyl acetate revealed binding-sites for calcium in the intercellular spaces of the epithelia interstitium and the mucus cells of the inner mantle epithelium. Precipitates were also seen after all incubations in the calcium spherites of the connective tissue. The concentrations of calcium and other elements were analysed in freeze-dried ultrathin sections of cryofixed mantle tissue by means of energy-dispersive X-ray microanalysis. Only in mitochondria of the musculature could high amounts of calcium and phosphorous be detected.

Animals↗