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At least 127 records · Page 7Linked to original sources
PubMed1973

Studies of human adipose tissue. Adipose cell size and number in nonobese and obese patients.

The cellular character of the adipose tissue of 21 nonobese and 78 obese patients has been examined. Adipose cell size (lipid per cell) was determined in three different subcutaneous and deep fat depots in each patient and the total number of adipose cells in the body estimated by division of total body fat by various combinations of the adipose cell sizes at six different sites. Cell number has also been estimated on the basis of various assumed distribution of total fat between the subcutaneous and deep fat depots. Obese patients, as a group, have larger adipose cells than do nonobese patients; cell size, however, varies considerably among the fat depots of individuals of either group. The variation in cell size exists not only between, but also within subcutaneous and deep sites. Estimates of total adipose cell number for a given individual based upon cell size can, therefore, vary by as much as 85%. On the basis of these studies it is suggested that the total adipose number of an individual is best and most practically estimated, at this time, by division of total body fat by the mean of the adipose cell sizes of at least three subcutaneous sites. IRRESPECTIVE OF THE METHOD BY WHICH TOTAL ADIPOSE CELL NUMBER IS ESTIMATED, TWO PATTERNS OF OBESITY EMERGE WITH RESPECT TO THE CELLULAR CHARACTER OF THE ADIPOSE TISSUE MASS OF THESE PATIENTS: hyperplastic, with increased adipose cell number and normal or increased size, and hypertrophic, with increased cell size alone. These two cellular patterns of obesity are independent of a variety of assumed distributions of fat among the subcutaneous and deep depots. When these different cellular patterns are examined in terms of various aspects of body size, body composition, and the degree, duration, and age of onset of obesity, only the latter uniquely distinguishes the hyperplastic from the hypertrophic: hyperplastic obesity is characterized by an early age of onset, hypertrophic, by a late age of onset. These studies indicate that there are two distinct periods early in life during which hypercellularity of the adipose tissue are most likely to occur: very early within the first few years, and again from age 9 to 13 yr.

Adipose Tissue↗
PubMed2000

Plant cell-size control: growing by ploidy?

The size of plant cells is determined by genetic, structural and physical factors as well as by internal and external signals. Our knowledge of the molecular mechanisms of these controls is still rudimentary. Recent studies indicate that ploidy level exerts an important control on cell size. By increasing ploidy, endoreduplication may allow cells to reach extraordinary sizes. This process is widespread in plants and may provide a means to manipulate the cell volume.

Cell Cycle↗
PubMed1985

Uptake of hematoporphyrin derivative by normal and malignant cells: effect of serum, pH, temperature, and cell size.

Normal and malignant cells were incubated with hematoporphyrin derivative (HPD) and their uptake and retention of HPD were analyzed by flow cytometry. In standard growth medium the amount of HPD taken up by cells was proportional to the added HPD concentration and reached a plateau level after 5-6 h of incubation. The uptake occurred in two steps; within seconds a large amount of HPD became loosely bound to the cells, presumably the outer membrane. This was followed by a slower uptake of HPD into the cytoplasm. The loosely bound portion could be washed from the cells by medium containing either fetal calf serum or serum albumin. At low temperatures the uptake into the cytoplasm was strongly reduced. A major determinant of HPD uptake was the concentration of serum in the medium. At any particular concentration of HPD below 200 mg/liter, increasing concentrations of fetal calf serum or bovine serum albumin resulted in a reduction in the amount of HPD taken up by cells. A further factor affecting uptake was the pH of the medium. At low pH (pH 6) the rate of HPD incorporation was much higher than at pH 7.4. Under identical conditions of incubation, HPD uptake was proportional to cell size as estimated using the low angle light scatter signal in the flow cytometer. Our data suggest that acidic pH, differences in extracellular serum concentrations of malignant tumor tissue, as well as the increased size of tumor cells may play an important role in the selective uptake of HPD by malignant tumors.

Animals↗
PubMed1985

Cell growth, cell division and cell size homeostasis in Swiss 3T3 cells.

By separating large and small 3T3 cells we show here that cell growth (in volume) after stimulation from quiescence is not 'autocatalytic'. Rather, large cells grow significantly more slowly, in relative terms, than small cells. It follows that 3T3 cells do not require a size control mechanism operating at the level of division timing in order to achieve cell size homeostasis.

Animals↗
PubMed2006

Generation of cell lines with tetracycline-regulated autophagy and a role for autophagy in controlling cell size.

Autophagy is an intracellular bulk degradation system. We established mouse fibroblast lines coupling the Tet-off system with an Atg5(-/-) mouse embryonic fibroblast line to artificially regulate autophagic ability. In the presence of doxycycline (Dox), Atg5 expression was completely suppressed and these cells were autophagy-defective. After removal of Dox, autophagic ability was restored within 6h. Very low levels of Atg5 could induce an autophagy competent state. We applied this novel system to examine the contribution of autophagy to controlling cell size. Cell size reduction in response to starvation was significantly inhibited in cells unable to undergo autophagy. The generated cell lines will be useful reagents for future mechanistic studies into the regulation and physiologic significance of autophagy.

Animals↗
PubMed2002

Changes in aspects such as the collagenous fiber density and foam cell size of atherosclerotic lesions composed of foam cells, smooth muscle cells and fibrous components in rabbits caused by all-cis-5, 8, 11, 14, 17-icosapentaenoic acid.

Atherosclerotic plaques composed of foamed macrophages, smooth muscle cells and fibrous components in the twice-injured carotid artery from 1% cholesterol diet (HCD)-fed rabbits were prepared and the effects of all-cis-5, 8, 11, 14, 17-icosapentaenoic acid (EPA) on the histopathological properties of atherosclerotic lesions were examined. During the test period, there was no significant difference between the control and the EPA-treated groups in serum lipid levels. In the control group, atherosclerotic lesions were composed of foamed macrophages, smooth muscle cells and fibrous components. Some of the lesions had a large core of foamed macrophages covered with a thin cap of smooth muscle cells and fibrous components, and were morphologically similar to human vulnerable plaques. The classification of plaques, composing atherosclerotic lesions based on collagenous fiber density and foam cell size indicated that over 70% of plaques in the control group were poor in collagenous fiber, while about 20% of plaques contained only large foam cells. In contrast to the control group, over 70% of plaques in the EPA-treated group were rich in collagenous fiber and only 3% consisted of large foam cells. These results suggest that EPA changes certain aspects of pre-existing atherosclerotic lesions.

Animals↗
PubMed2005

SFP1 is involved in cell size modulation in respiro-fermentative growth conditions.

Saccharomyces cerevisiae grows fast on glucose, while growth slows down on ethanol as cells move from glucose fermentation to oxidative metabolism. The type of carbon source influences both the specific growth rate and cell cycle progression, as well as cell size. Yeast cells grown on glucose have a larger size than cells grown on ethanol. Here, we analysed the behaviour of a sfp1 null mutant during balanced and transitory states of growth in batch in response to changes in the growth medium carbon sources. In a screening for mutants affected in cell size at Start, SFP1 has been identified as a gene whose deletion caused one of the smallest whi phenotype. Findings presented in this work indicate that in the sfp1 null mutant the reduction in cell size is not only a consequence of the reduced growth rate but it is tightly linked to the cellular metabolism. The SFP1 gene product is required to sustain the increase of both rRNA and protein content that in wild-type cells takes place in respiro-fermentative growth conditions, while it seems dispensable for growth on non-fermentable carbon sources. It follows that sfp1 cells growing on ethanol have a larger size than cells growing on glucose and, noticeably, the former enter the S phase with a critical cell size higher than the latter. These features, combined with the role of Sfp1p as a transcriptional factor, suggest that Sfp1p could be an important element in the control of the cell size modulated by nutrients.

Cell Cycle↗
PubMed2006

Static magnetic fields affect cell size, shape, orientation, and membrane surface of human glioblastoma cells, as demonstrated by electron, optic, and atomic force microscopy.

BACKGROUND: It is common knowledge that static magnetic fields (SMF) do not interact with living cells; thus, fewer studies of SMF compared with variable magnetic fields are carried out. However, evidence demonstrated that SMF affect cellular structures. To investigate the effect of exposure to increasing doses of SMF on cell morphology, human glioblastoma cells were exposed to SMF ranging between 80 and 3,000 G (8 and 300 mT). METHODS: Cell morphology of human glioblastoma cells, derived from a primary culture, was studied by electron and optic microscopy. FITC-phalloidin staining of actin filaments was also investigated. Finally, cell surface structure changes were detected by atomic force microscopy. RESULTS: Scanning electron microscopy demonstrated a dose-dependent cell shape modification, progressive cell detachment, loss of the long villi, and appearance of membrane roughness and blebs. FITC-phalloidin staining confirmed the villi retention and cell dimension decrease. At 3,000 G, the appearance of apoptotic morphology was also observed by transmission electron microscopy. Cell exposed to SMF showed different orientation and alignment when compared with nonexposed cells. The atomic force microscopy of the exposed cells' membrane surfaces demonstrated the disappearance of the ordered surface ripples and furrows typical of the unexposed cells, and the occurrence of surface membrane corrugation at increasing dose exposure CONCLUSIONS: Our experimental procedures demonstrated that exposure to SMF affects not only cell size, shape, and orientation but also human glioblastoma cells' membrane surfaces.

Apoptosis↗
PubMed2003

Cell size as a link between noncoding DNA and metabolic rate scaling.

Accumulation of noncoding DNA and therefore genome size (C-value) may be under strong selection toward increase of body size accompanied by low metabolic costs. C-value directly affects cell size and specific metabolic rate indirectly. Body size can enlarge through increase of cell size and/or cell number, with small cells having higher metabolic rates. We argue that scaling exponents of interspecific allometries of metabolic rates are by-products of evolutionary diversification of C-values within narrow taxonomic groups, which underlines the participation of cell size and cell number in body size optimization. This optimization leads to an inverse relation between slopes of interspecific allometries of metabolic rates and C-value. To test this prediction we extracted literature data on basal metabolic rate (BMR), body mass, and C-value of mammals and birds representing six and eight orders, respectively. Analysis of covariance revealed significant heterogeneity of the allometric slopes of BMR and C-value in both mammals and birds. As we predicted, the correlation between allometric exponents of BMR and C-value was negative and statistically significant among mammalian and avian orders.

Animals↗
PubMed2002

Purkinje cell size is reduced in cerebellum of patients with autism.

1. The authors' goal was to compare the size and density of Purkinje cells in the cerebellum of subjects with and without autism. Blocks of cerebellum were dissected at autopsy from the brains of age, sex- and postmortem-intervaled (PMI) groups of autistic and normal control individuals (N = 5 per group). Frozen, unfixed blocks were sectioned and stained with 1% cresyl violet. 2. The linear, molecular, granular densities and cross-sectional area of Purkinje cells were measured using computer-assisted image analysis. The average cross-sectional areas of Purkinje cells of the patients with autism were smaller by 24% when compared to the normal subjects. Two of the five autistic subjects had mean Purkinje cell sizes that corresponded to greater than 50% reduction in size. There was a substantial effect size difference in Purkinje cell size (eta2 = 0.29) between control and autistic brains (F(1, 8) = 3.32, P = 0.106). No differences in Purkinje cell densities were observed between the two groups 3. These data indicate the possibility of Purkinje cell atrophy in autism with significant neurohistological heterogeneity among individuals diagnosed with this disorder.

Adult↗
PubMed1972

Effect of cell size on lipolysis and antilipolytic action of insulin in human fat cells.

The lipolytic response to catecholamines and the antilipolytic effect of $$Word$$ were studied as a function of adipose cell size and number. The results show that cellular enlargement is associated with an increase in the basal lipolysis as well as the release of glycerol induced by salbutamol (a beta(2)-receptor agonist), noradrenaline, adrenaline, and isopropyl-noradrenaline. The glycerol release induced by all these agents seems to be more favorably correlated with cell surface area than with cell volume or diameter. Under the incubation conditions used with glucose in the medium, the antilipolytic effect of insulin on the basal as well as on the adrenaline- and isopropylnoradrenaline-stimulated lipolysis was not consistent at any cell size studied. However, in the presence of noradrenaline and salbutamol, insulin exerted a consistent antilipolytic effect. The results show that the larger adipose cells are at least as sensitive to the antilipolytic effect of insulin as the smaller cells. The results imply that the previously reported diminished responsiveness to insulin shown by large adipose cells is exerted only on the side of lipid accumulation. It is suggested that the negative correlation between cell size and responsiveness to insulin on the side of lipid accumulation may be one way to control adipose cell enlargement.

Adipose Tissue↗
PubMed2006

Two system-size-resonance behaviors for calcium signaling: for optimal cell size and for optimal network size.

We have studied the collective calcium signaling behavior of an array of coupled N cells, taking into account the internal noises resulting from the small cell size V. The system's performance was characterized by the reciprocal coefficient of variance (RCV) of the calcium spike train. Two system-size resonances were observed, namely, the RCV value shows a clear peak when both N and V are optimal. Therefore, an optimal number of cells of optimal size work the best as a whole.

Animals↗
PubMed1982

Quantitative aspects of red cell size variation during pregnancy.

Red cell volume distribution curves may be readily obtained using electronic cell counters, and the proportion of cells that deviate from the normal population may be determined. In this study, we report the results of red cell volume distribution analyses in pregnant and non-pregnant females. The relationship between red cell volume distribution and other red cell indices is also studied. Statistical analysis showed good correlation between various Channelyzer parameters and red cell indices including Hb, RCC, MCV, MCH, and MCHC. A significant proportion of pregnant patients showed abnormal red cell volume distribution curves particularly in the latter half of pregnancy. During the latter half of pregnancy there was an increased proportion of microcytic cells in 8% of patients and evidence for macrocytosis was found in 67% of patients. In general there was good correlation between stages of gestation and Channelyzer parameters associated with macrocytosis. It is suggested that analysis of red cell size, which may be simply performed with minimal quantities of blood and inconvenience using the Channelyzer, could give insight into those conditions associated with variation in red cell size including iron deficiency and folate deficiency in pregnancy and it is conceivable that repeated estimations of these parameters could obviate the need for blanket administration of haematinics to the pregnant patient.

Adult↗
PubMed2006

Quantification of cell size distribution as applied to the growth of Corynebacterium glutamicum.

It is known that the cell size is related to the physiological state of a cell. Therefore, cell size distribution directly reflects the average physiological properties of the cell culture. Cell size distribution can be enumerated by image analysis, flow cytometry and coulter counter. In this study, image analysis was used to characterize the cell size distribution during the growth of Corynebacterium glutamicum and was further analyzed by a distribution function. The parameters of the distribution function indicate the mean value and spread of the distribution. Analysis demonstrated that the maximum specific growth rate was higher (0.67h(-1)) for the growth obtained through serial dilution of seed as compared to growth from a normal seed culture (0.53h(-1)). This was due to a greater percentage of the cell population being in the state of division for the growth through serial dilution in the mid-log phase. The measurement of the cell size distribution demonstrated that the average cell size decreased during the course of growth. The distribution function was also used to enumerate the average specific growth rate of both the conditions of the culture. The demonstrated methodology can be used to predict an average growth property of a cell culture.

Bacteriological Techniques↗
PubMed1997

Cell size control and a cell-intrinsic maturation program in proliferating oligodendrocyte precursor cells.

We have used clonal analysis and time-lapse video recording to study the proliferative behavior of purified oligodendrocyte precursor cells isolated from the perinatal rat optic nerve growing in serum-free cultures. First, we show that the cell cycle time of precursor cells decreases with increasing concentrations of PDGF, the main mitogen for these cells, suggesting that PDGF levels may regulate the cell cycle time during development. Second, we show that precursor cells isolated from embryonic day 18 (E18) nerves differ from precursor cells isolated from postnatal day 7 (P7) or P14 nerves in a number of ways: they have a simpler morphology, and they divide faster and longer before they stop dividing and differentiate into postmitotic oligodendrocytes. Third, we show that purified E18 precursor cells proliferating in culture progressively change their properties to resemble postnatal cells, suggesting that progressive maturation is an intrinsic property of the precursors. Finally, we show that precursor cells, especially mature ones, sometimes divide unequally, such that one daughter cell is larger than the other; in each of these cases the larger daughter cell divides well before the smaller one, suggesting that the precursor cells, just like single-celled eucaryotes, have to reach a threshold size before they can divide. These and other findings raise the possibility that such stochastic unequal divisions, rather than the stochastic events occurring in G1 proposed by "transition probability" models, may explain the random variability of cell cycle times seen within clonal cell lines in culture.

Age Factors↗
PubMed2000

Do growth and cell division rates determine cell size in multicellular organisms?

Studies in yeast have provided some clues to how cell size might be determined in unicellular eukaryotes; yet little attention has been paid to this issue in multicellular organisms. Reproducible cell sizes might be achieved in the dividing cells of multicellular organisms by the coordination of growth with cell division. Recently, mutations in genes encoding homologues of components of the mammalian insulin/phosphoinositide 3-kinase signalling pathway have been shown to affect organ growth and cell size during Drosophila melanogaster imaginal disc development. The data suggest that signalling through this pathway alters cell size because it primarily affects the growth of these organs (i.e. their increase in mass) and does not have a proportional impact on cell division. These observations are in keeping with the hypothesis that growth and cell division are regulated independently, and that cell size is just a consequence of the rate at which tissues grow and the cells within them divide. However, signalling through this pathway can affect cell cycle phasing and at least influence cell division. These interactions may provide a means of coordinating growth and cell division, such that cells divide only when they are above a minimum size.

Animals↗
PubMed1992

Induction of terminal differentiation in cultured human keratinocytes by polychlorinated aromatic hydrocarbons as measured by cell size analysis.

Polychlorinated aromatic hydrocarbons modulate the proliferation and differentiation of human epidermal cells in vivo and in culture. One of the earliest events in the process of terminal differentiation is the increase in cell size. In this report the usefulness of morphometric cell size analysis as a quantifiable marker for chemical-induced differentiation was examined. Concentration-related increases in cell size distribution were induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and 2,3,4,7,8-pentachlorodibenzofuran in normal human keratinocytes and cells from an SV40-transformed keratinocyte cell line (SVK14) whereas the analog 1,2,3,4-tetrachlorodibenzo-p-dioxin did not affect the cell size distribution up to a concentration of 100 nM. The minimal effective concentrations of five 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins/dibenzofurans and a coplanar polychlorbiphenyl necessary to induce an increase in cell size distribution were determined in SVK14 cells. It was found that the potency of these compounds relative to that of 2,3,7,8-TCDD correlated well with the toxicity equivalency factors observed in other test systems. This indicates that the keratinocyte cell assay is a useful method for establishing the relative potency of various "dioxins" and their mixtures.

Cells, Cultured↗
PubMed2004

Insulin reduces apoptosis and increases DNA synthesis and cell size via distinct signalling pathways in Drosophila Kc cells.

During development of Drosophila, cell proliferation and size are known to be regulated by insulin. Here we use Drosophila Kc cells to examine the molecular basis for the control of cell growth by insulin. Growing cells in the presence of insulin increased cell number above control levels at 16, 24, 48 and 72 h. We have demonstrated a novel anti-apoptotic effect of insulin (approximately 50%) in these cells, measured by caspase 3-like activity, which contributed to the increase in cell number. The anti-apoptotic effect was observed both in control cells and those in which apoptosis was induced by ultraviolet irradiation. An approximately 2-fold stimulation of bromodeoxyuridine incorporation demonstrated that insulin also increased Kc cell proliferation by stimulating new DNA synthesis. The ability of insulin to increase cell number, stimulate bromodeoxyuridine incorporation and reduce caspase 3-like activity was prevented by PD98059, which inhibits activation of the Drosophila extracellular signal regulated kinase (DERK) pathway, and was unaffected by wortmannin, an inhibitor of Drosophila phosphatidylinositol 3-kinase (DPI3K). Insulin also increased cell size approximately 2-fold and this was prevented by wortmannin and rapamycin, an inhibitor of Drosphilia target of rapamycin (DTOR). In summary, we show that DERK plays an important role in mediating the effect of insulin to reduce apoptosis and increase DNA synthesis whereas the DPI3K/DTOR/Dp70S6 kinase pathway mediates effects of insulin on cell size in Drosophila Kc cells.

Androstadienes↗