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PubMed1981

Changes in the sulfated proteoglycans synthesized by "aging" chondrocytes. II. Organ-cultured vertebral columns.

Sulfated proteoglycans synthesized by intact embryonic chick vertebral cartilages maintained in organ culture were characterized by labeling the vertebral chondrocytes with [35S]sulfate. More than 95% of the sulfated macromolecules synthesized by the cartilages are retained in their extracellular matrix. Sucrose velocity sedimentation gradient analyses revealed that the intact cartilages synthesized primarily proteoglycan monomers typical of cartilage and also small amounts of a smaller sized proteoglycan. The continuously varying size distribution of monomers which characterize a population of proteoglycans, could, in part, be attributed to heterogeneity of other chondroitin sulfate chain size. Changes in the proteoglycans synthesized by intact cartilages were analyzed between 6 h and 8 days of organ culture: (i) monomers decreased in molecular size with age in organ culture; (ii) the decrease in monomer size could be partially attributed to a shortening of their chondroitin sulfate chains; (iii) the 6S/4S disaccharide composition of the chondroitin sulfate chains also changed with culture age, from 1.8 to 0.3. This change was shown to be independent of the concomitant decrease in monomer size. These changes are similar to those which occur in proteoglycans synthesized by articular cartilages from chickens of increasing age. This cartilage culture system is likely to be a more useful model for studying changes which accompany aging and/or senescence in cartilage in vivo than the more commonly studied dispersed chondrocyte cultures.

Animals↗
PubMed1993

Human plasma phospholipid transfer protein causes high density lipoprotein conversion.

The effect of human plasma phospholipid transfer protein (PLTP) on the particle size distribution of human high density lipoprotein (HDL) was studied by incubating human HDL3 (particle diameter, 8.7 nm) together with PLTP in vitro. Incubation of HDL3 with highly purified preparations of PLTP, devoid of cholesterol ester transfer protein (CETP), induced a conversion of the homogenous population of HDL particles into two main populations of particles, one larger, particle diameter 10.9 nm, and one smaller, particle diameter 7.8 nm, than the original HDL3. These size changes were evident as analyzed by gradient gel electrophoresis and by high resolution gel filtration. The degree of the conversion was dependent on the amount of PLTP added to the incubation and on incubation time. An inhibitory monoclonal antibody (TP-1) directed against CETP had no effect on the HDL conversion. The PLTP used was purified to homogeneity from human plasma using ultracentrifugation and a combination of hydrophobic, cation-exchange, heparin-Sepharose-, anion-exchange, and gel filtration chromatographies. The monoclonal anti-CETP antibody (TP-1), which inhibits lipid transfer catalyzed by CETP, did not react with PLTP or inhibit its activity. The estimated molecular weight of PLTP is 75,000. The present study demonstrates that PLTP can act like the putative conversion factor and has the ability to convert HDL3 into populations of larger and smaller HDL particles. The mechanism(s) involved in this process and its physiological relevance remain to be established.

Carrier Proteins↗
PubMed1984

Early origin and pervasiveness of cellular heterogeneity in some malignant transformations.

Nontransformed BALB/3T3 cells were passaged weekly in monolayer culture on plastic dishes and aliquots were regularly assayed for colony production when suspended in agar. During several months of passaging, a single large colony arose once in the agar assay, and its constituent cells were isolated to form a subline of transformed cells. These cells had the fusiform and rounded morphologies characteristic of transformed cells and had a colony-forming efficiency in agar (CFEag) of approximately 10%. Five of the agar colonies were isolated at random and the cell populations of these primary subclones were further analyzed. Four of the five subclonal populations differed from each other in appearance slightly, but consistently, while the fifth had a markedly different colonial morphology. They also differed from one another in CFEag as well as in average diameter of the agar colonies. These general differences among the five subclones remained, although the CFEag and colony sizes changed recognizably in repeated weekly transfers. All of the subclones produced sarcomas in nude mice but did so at different rates. A secondary generation of five subclones was derived from each of three of the original subclonal populations. All the secondary subclones had the same morphology as the primary subclones from which they were derived. The averages of the CFEag and colony sizes of the secondary subclones from each of the subclones differed as a group from the other groups, but they also differed, to a lesser extent, among themselves. Despite the differences noted among the primary subclones in morphology, growth in agar, and tumor production in mice, they were virtually identical in their rapid growth rate on a plastic surface and all shared a high rate of glucose consumption. A second transformed clone arose among the continuously passaged nontransformed cells 5 months after the first one had appeared. Subclones of this clone did not differ recognizably from one another in morphology or in CFEag. The results indicate that recognizable heterogeneity can arise in some tumors during the earliest stages of their development and involve a high proportion of their constituent cells, while it may not become evident in other tumors until much later.

Animals↗
PubMed1985

The direct effects of interleukin 1, interleukin 2, interferon-alpha, interferon-gamma, B-cell growth factor, and a B-cell differentiation factor on resting and activated human B cells.

A wide variety of cytokines have been demonstrated to affect B-cell function. However, it is unclear which of these mediators actually exert direct effects on the B cells themselves. In the present study, the direct role of interleukin (IL) 1, IL-2, Interferon-gamma, or Interferon-alpha in human B-cell activation, proliferation, or differentiation was examined and compared with the effects of a B-cell growth factor (BCGF) or a B-cell differentiation factor (BCDF). Highly purified human B lymphocytes were separated according to size into two nonoverlapping populations. The fraction of small B cells was incubated with IL-1, IL-2, Interferon-gamma, Interferon-alpha, BCGF, or BCDF, and cell size changes, RNA synthesis, DNA synthesis, or supernatant immunoglobulin (Ig) production were measured. Neither IL-1, IL-2, Interferon-alpha, Interferon-gamma, nor the BCGF induced substantial cell size changes, RNA synthesis, DNA synthesis, or Ig production by the small fraction of B lymphocytes; however, the BCDF could directly activate a proportion of resting B lymphocytes to secrete Ig. The fraction of large B cells was also incubated with these cytokines. While neither IL-1, Interferon-alpha, nor Interferon-gamma enhanced DNA synthesis or Ig production by the fraction of large B lymphocytes, DNA synthesis was augmented 23-fold by BCGF and IgG production was increased 7-fold by BCDF. Additionally, IL-2 slightly enhanced both proliferation and differentiation of large B cells but substantially less so than BCGF and BCDF; DNA synthesis was increased 4-fold, while Ig production in the presence of IL-2 was increased by approximately 50%. Thus, the most important lymphokines modulating the function of these two fractions of tonsillar lymphocytes were a BCGF and a BCDF.

B-Lymphocytes↗
PubMed1976

Changes in liver cells ploidy of young rats following isoprenaline treatment.

Cell proliferation induced by isoprenaline (IPR) stimulation in very high doses was assayed in the liver of young rats, and the formation of polyploid cells was studied form the 15th to the 70th day of life. A general stimulatory effect on a complex process of cellular multiplication, leading to a population of tetraploid cells, was found to be accelerated; the earlier appearance of binucleate cells and the subsequent significant variations in their incidence confirmed the role of this cell type as an intermediate step in the process of polyploidization. Evidence was found of concomitant size changes of the hepatocytes, which might be partially independent of the effect of DNA content. The stimulation was no longer evident 20--30 days from the end of treatment, by when the cells which had come into contact with IPR should have completed the whole sequence of events leading to the formation of tetraploid mononucleate cells.

Animals↗
PubMed1984

An empirical method for converting nucleolar counts to neuronal numbers.

Our goal is to estimate neuronal numbers from counts of nucleolar profiles. The primary difficulty is that a simple way to convert the counts to the numbers, especially when multiple nucleoli are present in a nucleus, is not available. In this paper, we propose a solution. The formula is N = n X [N(c.f.)/n(c.f.)] where N = the true number of neurons, n = the number of nucleolar profiles in these neurons, N(c.f.) = the number of neurons used to estimate the correction factor and n(c.f.) = the number of nucleolar profiles found in the neurons that make up N(c.f.). The constraints are that the neurons identified for N(c.f.) be representative of the entire population, N; that the nucleolar profiles be counted by the same criteria when n(c.f.) is determined as when n is determined, and that when the correction factor [N(c.f.)/n(c.f.)] is calculated, the nucleolar profiles in each neuron be counted only once. The advantages are simplicity, and generality; the latter resulting from the empirical nature of the correction factor which can calibrate for multiple nucleoli, split nucleoli, invisible fragments, nucleolar size changes, section thickness differences and any other factors that cause n to deviate from N.

Animals↗
PubMed1988

Functional and phenotypic characterization of human B lymphocyte subsets isolated by unit gravity sedimentation.

We report the use of unit gravity sedimentation with a CelSep apparatus to generate two volumetrically similar but functionally and phenotypically distinct subsets of human peripheral blood B cells. One subset, comprised of small B lymphocytes, underwent a significant size change in response to anti-mu, proliferated synergistically to low concentrations of anti-mu plus B cell growth factor (BCGF) or phorbol myristate acetate plus BCGF, and could be induced to produce immunoglobulin in response to pokeweed-mitogen-derived T-lymphocyte-replacing factors. These cells were primarily sIg+, B1+, B2+, and were virtually free of monocytes (less than 0.01%). Unlike these resting B lymphocytes, the large cells proliferated directly to BCGF, without displaying synergy with anti-mu. These cells displayed very little B2 (less than 7%), did not increase in volume in the presence of anti-mu, and made more immunoglobulin in response to TRF than the small resting B lymphocytes. However, neither population synthesized immunoglobulin spontaneously. This technique, which is highly reproducible, not equipment intensive, and produces high cell recovery (greater than 90%), allows for a precise analysis of the steps involved in the maturation of a resting B lymphocyte to an immunoglobulin-secreting cell.

B-Lymphocytes↗
PubMed1986

Cholinergic amacrine cells in the rat retina.

Staining of rat retinal wholemounts with a monoclonal antibody against choline-acetyl-transferase (ChAT) reveals two matching populations of amacrine cells in pigmented and albino rat retinae. One population has cell bodies in the inner nuclear layer (INL). Their dendrites are confined to a narrow stratum in the outer half of the inner plexiform layer (IPL). The other, displaced, population has cell bodies in the ganglion cell layer (GCL) with dendrites stratifying in the middle of the IPL. The density changes with eccentricity, ranging from 1,700 cells/mm2 centrally to 600 cells/mm2 in the periphery. Presumptive cholinergic cells were filled with the fluorescent dye Lucifer yellow. Both subpopulations have the same "starburstlike" morphology as described for rabbit cholinergic amacrine cells (Famiglietti, '83; Tauchi and Masland, '84; Masland et al., '84b). Their dendritic tree sizes change with eccentricity and range from 160 to 300 microns in diameter. Counterstaining of Lucifer yellow-filled cells by ChAT immunohistochemistry did not yield an unequivocal double staining. Nevertheless, indirect evidence of same soma size, same number and form of primary dendrites, same level of stratification, and the good fit into the cholinergic mosaic makes it very likely that the "starburstlike" amacrine cells in the rat use acetylcholine as their transmitter. A comparison with the rabbit cholinergic system strengthens this assumption and reveals a striking similarity between both species.

Animals↗
PubMed1976

Endotoxin-induced size change in bone marrow progenitors of granulocytes and macrophages.

Injection of 5 mug endotoxin to adult C57BL mice caused a marked increase in the sedimentation velocity of granulocytic and macrophage progenitor (colony-forming) cells in the bone marrow. This change was maximal two days after injection and was not accompanied by corresponding changes in total marrow nucleated cell populations. The endotoxin-induced shift was not dependent on the presence of the thymus but did not occur in mice challenged after preinjection with endotoxin. No changes in buoyant density, cell cycle status, pattern of differentiation and responsiveness of granulocytic and macrophage progenitor cells were observed after the injection of endotoxin. The increased sedimentation velocity of progenitor cells appears to indicate an increase in cell volume but the mechanisms involved have not been identified.

Animals↗
PubMed1993

Separation and size distribution of red blood cells of diverse size, shape, and origin by flow/hyperlayer field-flow fractionation.

Red blood cells (RBCs) from human, equine, canine, feline, and bovine whole blood samples have been separated and characterized by high-speed flow/hyperlayer field-flow fractionation (Fl/HyFFF). The elution-based separation of RBCs by this method is based mainly on the size and shape of the cell particles. The typical separation time for RBCs is less than 3 min. Size distributions can be derived from the fractograms of cell samples using a calibration plot based on retention data for uniform polystyrene beads. The method is shown to be effective both to separate and to characterize cell populations, including those with cells of abnormal shape and size. In order to investigate differences in cell morphology, shape and size changes induced by 500,000 Da Dextran were monitored. The changes in the Fl/HyFFF elution profiles indicate that the RBCs decrease in size but become partially aggregated in the presence of the dextran. These changes were found to depend on polymer concentration and specific blood samples. Some of the results from Fl/HyFFF were compared with those from the Coulter counter and from microscopy.

Animals↗
PubMed1994

A Sau3A polymorphism in the 5' end of the IT15 gene that nonrandomly segregates with the Huntington disease trinucleotide expansion.

Genomic clones encompassing the Huntington disease (HD) mutation were used to isolate a probe that detects size changes in the restriction fragments that contain the HD trinucleotide repeat (TNR). This probe also detects a frequent Sau3A polymorphism (allele sizes 1.8-kb and 2.7kb), which maps approximately 950bp from the TNR. Examination of a number of HD families established that the frequency of the Sau3A alleles did not differ significantly between control and HD populations; however, the HD expansion was always present on a chromosome that contained the 1.8-kb Sau3A allele. This association between a specific allele and the HD TNR expansion was significant and could provide a clue to the chromosomal elements that produce the trinucleotide expansion on the Huntington disease chromosome.

Alleles↗
PubMed1986

Size and contrast have only small effects on the responses to faces of neurons in the cortex of the superior temporal sulcus of the monkey.

There is a population of neurons in the cortex in the middle and anterior part of the superior temporal sulcus (STS) of the monkey with responses which are selective for faces. To investigate whether the responses of these neurons show some of the perceptual properties of face recognition such as tolerance to changes in the size and contrast of the face, the effects of alteration of the size and contrast of an effective face stimulus on the responses of these neurons were analysed quantitatively in macaque monkeys. First, it was shown that the majority of these neurons had responses which were relatively invariant with respect to the size of the stimulus. The median size change tolerated with a response of greater than half the maximal response was 12 times. Second, it was found that for a few of these neurons, the size of the face did affect the neuronal response. For most of these neurons, it was found that when the size of the image and its distance were altered, the neuronal response was related to the retinal angle subtended by the image. But for four neurons the absolute size of the image determined the magnitude of the neuronal response, independently of the distance of the image. Thus these four neurons showed size constancy. It is suggested that these neurons would be useful as part of a face recognition system, because only objects in a certain absolute size range should normally be classified as faces. Third, the responses of the neurons were relatively invariant with respect to the contrast of the face. The mean contrast at which the neurons still responded with more than half the maximal response was 0.26. Fourth, the responses of the neurons were relatively invariant with respect to the sign of the contrast of the face, that is the neurons responded to negative as well as to positive images of faces. Fifth, the neurons typically responded to a face when the information in it had been reduced from 3D to a 2D representation in gray on a monitor, with a response which was on average 0.5 that to a real face. These results show that the responses of these neurons have some of the invariant properties with respect to size and contrast alteration shown by face perception, and show that their processing is at a level which would be useful in face recognition.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1989

Temperature-induced fusion of small unilamellar vesicles formed from saturated long-chain lecithins and diheptanoylphosphatidylcholine.

Small unilamellar vesicles which form when gel-state long-chain phosphatidylcholines are mixed with micellar short-chain lecithins undergo an increase in size as the long-chain species melts to its liquid-crystalline form. Analysis of the vesicle population with quasi-elastic light scattering shows that the particle size increases from 90-A radius to greater than 5000-A radius. Resonance energy transfer experiments show total mixing of lipid probes with unlabeled vesicles only when the Tm of the long-chain phosphatidylcholine is exceeded. This implies that the large size change represents a fusion process. Aqueous compartments are also mixed during this transition. 31P NMR analysis of the vesicle mixtures above the phase transition shows a great degree of heterogeneity with large unilamellar particles coexisting with oligo- and multilamellar structures. Upon cooling the vesicles below the Tm, the original size distribution (e.g., small unilamellar vesicles) is obtained, as monitored by both quasi-elastic light scattering and 31P NMR spectroscopy. This temperature-induced fusion of unilamellar vesicles is concentration dependent and can be abolished at lower total phospholipid concentrations. It occurs over a wide range of long-chain to short-chain ratios and occurs with 1-palmitoyl-2-stearoylphosphatidylcholine and dimyristoylphosphatidylcholine as well. Characterization of this fusion event is used to understand the anomalous kinetics of water-soluble phospholipases toward these unusual vesicles.

Kinetics↗
PubMed1985

Size changes of protamine 1 mRNA provide a molecular marker to monitor spermatogenesis in wild-type and mutant mice.

We utilized a cDNA encoding the cysteine-rich, tyrosine-containing mouse protamine, mouse protamine 1 (MP1), to detect the presence of several classes of differentiating germ cells in testicular extracts from wild-type and male sterile mutant mice. This assay is based on the changes in the poly (A) length of MP1-mRNA during spermatogenesis. Testicular extracts of sexually mature CD-1 mice contain a heterogeneous population of protamine-1 mRNA ranging in length from 450 to 580 nucleotides. When the protamine-1 probe was hybridized to testicular RNA preparations from 16- to 20-day-old animals, no MP1-mRNA was detected. Twenty-four-day-old mice contain only the 580-nucleotide form of MP1-mRNA. This size class of protamine mRNA is also present in purified populations of round spermatids, whereas elongating spermatids and residual bodies contain mRNAs ranging from 450 to 580 nucleotides in length, which are identical in size to those present in the testes of sexually mature animals. When the protamine cDNA probe was used to examine the progression of spermiogenesis in three male sterile mouse mutants, blind sterile (bs), quaking (qk) and testicular feminization (Tfm), the results demonstrated that each mutant is pathologically distinct. Analysis of the bs mutant revealed a diminution in the amount of both size classes of MP1-mRNA, in agreement with the cytological reports of reduced numbers of haploid spermatogenic cells in these animals. The presence of both size classes of protamine mRNA in the qk mutant indicates that germ-cell differentiation has proceeded at least to the step-12 spermatid in these animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Androgen-Insensitivity Syndrome↗
PubMed1987

Genome size variation in North American minnows (Cyprinidae). II. Variation among 20 species.

Genome sizes (nuclear DNA contents) from 200 individuals representing 20 species of North American cyprinid fishes (minnows) were examined spectrophotometrically. The distributions of DNA values of individuals within populations of the 20 species were essentially continuous and normal; the distribution of DNA values among species was continuous and overlapping. These observations suggest that changes in DNA quantity in cyprinids are small in amount, involve both gains and losses of DNA, and are cumulative and independent in effect. Significant heterogeneity in mean genome size occurs both between individuals within populations of species and among species. The former averages maximally around 6% of the cyprinid genome and is nearly the same as the amount of DNA theoretically needed for the entire cyprinid structural gene component. The majority of the DNA content variation among the 20 species is distributed above the level of individuals within populations. Comparisons of average genome size difference or distance between individuals drawn from different levels of taxonomic organization indicate that considerably greater divergence in genome size has occurred in the extremely speciose cyprinid genus Notropis as compared with other North American cyprinid genera. This may suggest that genome size change is concentrated in speciation episodes. Finally, no associations were found between interspecific variation in genome size and five life-history characters. This suggests that much of the variation in genome size within and among the 20 species may be phenotypically inconsequential.

Animals↗
PubMed1992

Age-related changes in glomerular volume and hydroxyproline content in rat and human.

Total 4-hydroxyproline content and volume were measured in the same sample of microdissected glomeruli obtained fro rat and human outer or inner cortex. Glomerular volume was determined by computer-assisted image analysis, and 4-hydroxyproline was measured by a highly sensitive gas-liquid chromatographic method. Results were expressed as weight of basement membrane material by comparison with the amount of 4-hydroxyproline in purified basement membrane/mesangial matrix preparations. Microanalyses were possible in samples containing as few as eight human glomeruli. Rat glomerular size increased sevenfold between 5 wk and 2 yr of age, with volume being consistently 36 to 45% greater in inner than in outer cortex glomeruli. Basement membrane material content per glomerulus markedly increased with age (12-fold); however, when expressed per unit volume, this change was greatly reduced (2-fold). Expressed per volume, inner and outer cortex glomerular content of basement membrane material was always similar, regardless of age. Therefore, a greater glomerular size, in itself, does not accelerate the rate of basement membrane material deposition. Glomerular size distributions (measured by skewness and kurtosis) did not change, indicating that, although glomerular volume increases with age, aging does not appear to cause the emergence of distinct glomerular populations within an age group. Basement membrane material accumulation is probably a generalized change. Human glomeruli increased sevenfold in size from infancy to adulthood and then declined during senescence. Contrary to that in the rat, glomerular basement membrane material content appeared to closely follow size changes, thus, varying little from infancy to senescence if expressed per unit of glomerular volume.

Adolescent↗