Cell Size Heterogeneity Research Articles

Red Cell Distribution Width and Mortality in Older Adults: A Meta-analysis

Red cell distribution width (RDW) is a quantitative measure of variability in the size of circulating erythrocytes with higher values reflecting greater heterogeneity in cell sizes. Recent studies have shown that higher RDW is associated with increased mortality risk in patients with clinically significant cardiovascular disease (CVD). Whether RDW is prognostic in more representative community-based populations is unclear. Seven relevant community-based studies of older adults with RDW measurement and mortality ascertainment were identified. Cox proportional hazards regression and meta-analysis on individual participant data were performed. Median RDW values varied across studies from 13.2% to 14.6%. During 68,822 person-years of follow-up of 11,827 older adults with RDW measured, there was a graded increased risk of death associated with higher RDW values (p < .001). For every 1% increment in RDW, total mortality risk increased by 14% (adjusted hazard ratio [HR]: 1.14; 95% confidence interval [CI]: 1.11-1.17). In addition, RDW was strongly associated with deaths from CVD (adjusted HR: 1.15; 95% CI: 1.12-1.25), cancer (adjusted HR: 1.13; 95% CI: 1.07-1.20), and other causes (adjusted HR: 1.13; 95% CI: 1.07-1.18). Furthermore, the RDW-mortality association occurred in all major demographic, disease, and nutritional risk factor subgroups examined. Among the subset of 1,603 older adults without major age-associated diseases, RDW remained strongly associated with total mortality (adjusted HR: 1.32; 95% CI: 1.21-1.44). RDW is a routinely reported test that is a powerful predictor of mortality in community-dwelling older adults with and without age-associated diseases. The biologic mechanisms underlying this association merit investigation.

Red Blood Cell Distribution Width and Mortality Risk in a Community-Based Prospective Cohort

Red blood cell distribution width (RDW), an automated measure of red blood cell size heterogeneity (eg, anisocytosis) that is largely overlooked, is a newly recognized risk marker in patients with established cardiovascular disease (CVD). It is unknown whether RDW is associated with mortality in the general population or whether this association is specific to CVD. We examined the association of RDW with all-cause mortality and with CVD, cancer, and chronic lower respiratory tract disease mortality in 15 852 adult participants in the Third National Health and Nutrition Examination Survey (1988-1994), a nationally representative sample of the US population. Mortality status was obtained by matching to the National Death Index, with follow-up through December 31, 2000. Estimated mortality rates increased 5-fold from the lowest to the highest quintile of RDW after accounting for age and 2-fold after multivariable adjustment (P(trend) < .001 for each). A 1-SD increment in RDW (0.98%) was associated with a 23% greater risk of all-cause mortality (hazard ratio [HR], 1.23; 95% confidence interval [CI], 1.18-1.28) after multivariable adjustment. The RDW was also associated with risk of death due to CVD (HR, 1.22; 95% CI, 1.14-1.31), cancer (1.28; 1.21-1.36), and chronic lower respiratory tract disease (1.32; 1.17-1.49). Higher RDW is associated with increased mortality risk in this large, community-based sample, an association not specific to CVD. Study of anisocytosis may, therefore, yield novel pathophysiologic insights, and measurement of RDW may contribute to risk assessment.

Generalized travel-time inversion on unstructured grids

We propose an extension to unstructured grids for the so-called generalized travel-time inversion method for inversion of production data. The framework of the inversion method applies directly to fully unstructured grids, but there are aspects regarding sensitivities and regularization that have to be addressed. First, we propose a generalized smoothing operator for the regularization to impose smooth modification on reservoir parameters. Second, to handle reservoir models with great heterogeneity in cell sizes, we investigate the use of rescaled sensitivities (average cell volume multiplied by local sensitivity density) in the inversion. We demonstrate the utility of our extensions on three synthetic cases in 2-D. First, we validate the inversion method by applying it to a reservoir model represented both on a Cartesian and on a refined triangular grid. Second, we apply the method for a highly unstructured grid with large differences in cell sizes. Third, we consider an example with faults and non-matching connections. All examples show that our method is able to match the data with the same quality as has been obtained earlier on structured grids and without degrading the realism of the reservoir parameters. Finally, we present a simple synthetic 3D case to illustrate that using rescaled sensitivities may be important to avoid unwanted grid-effects in models with strong variations in the thickness of the stratigraphic layers.

Abstract 1253: Increased Red Blood Cell Distribution Width is Associated with Greater Risk of All-Cause, Cardiovascular and Non-Cardiovascular Mortality in a Large Community-Based Cohort

Background: The red cell distribution width (RDW), a measure of red cell size heterogeneity (anisocytosis), is a newly recognized risk marker in patients with CVD. It is unknown whether RDW is associated with mortality in the general population. Methods and results: We examined the association of RDW with mortality risk among 14,953 adult participants in the Third National Health and Nutrition Examination Survey (1988 –1994), a representative sample of the United States population. Over a geometric mean of 8.3 years, 2,372 deaths occurred. Age-standardized mortality rates, excepting external-cause (i.e. accidental) deaths, increased across RDW quintiles (figure ). A one standard deviation increment in RDW (0.98) was associated with a 21% greater risk of all-cause (HR 1.21, 95% CI 1.15–1.26) and cardiovascular mortality (HR 1.21, 95% CI 1.13–1.29) after multivariable adjustment including hemoglobin level. RDW was also independently associated with risk of death due to cancer (HR 1.21, 95% CI 1.12–1.30) and chronic lower respiratory disease (HR 1.31, 95% CI 1.14 –1.52). Only age exceeded the statistical strength of RDW’s association with all-cause and cardiovascular mortality; only age and smoking were more strongly associated with cancer and chronic lower respiratory disease mortality. Conclusions: We found that higher RDW was strongly predictive of increased risk of all-cause, cardiovascular, and non-cardiovascular mortality in this large, community-based sample. Study of anisocytosis may therefore yield broad pathophysiological insights, and measurement of RDW may contribute to patient risk assessment.

ATP-dependent sugar transport complexity in human erythrocytes

Human erythrocyte glucose sugar transport was examined in resealed red cell ghosts under equilibrium exchange conditions ([sugar](intracellular) = [sugar](extracellular), where brackets indicate concentration). Exchange 3-O-methylglucose (3MG) import and export are monophasic in the absence of cytoplasmic ATP but are biphasic when ATP is present. Biphasic exchange is observed as the rapid filling of a large compartment (66% cell volume) followed by the slow filling of the remaining cytoplasmic space. Biphasic exchange at 20 mM 3MG eliminates the possibility that the rapid exchange phase represents ATP-dependent 3MG binding to the glucose transport protein (GLUT1; cellular [GLUT1] of </=20 microM). Immunofluorescence-activated cell sorting analysis shows that biphasic exchange does not result from heterogeneity in cell size or GLUT1 content. Nucleoside transporter-mediated uridine exchange proceeds as rapidly as 3MG exchange but is monoexponential regardless of cytoplasmic [ATP]. This eliminates cellular heterogeneity or an ATP-dependent, nonspecific intracellular diffusion barrier as causes of biphasic exchange. Red cell ghost 3MG and uridine equilibrium volumes (130 fl) are unaffected by ATP. GLUT1 intrinsic activity is unchanged during rapid and slow phases of 3MG exchange. Two models for biphasic sugar transport are presented in which 3MG must overcome a sugar-specific, physical (diffusional), or chemical (isomerization) barrier to equilibrate with cell water. Partial transport inhibition with the use of cytochalasin B or maltose depresses both rapid and slow phases of transport, thereby eliminating the physical barrier hypothesis. We propose that biphasic 3MG transport results from ATP-dependent, differential transport of 3MG anomers in which V(max)/apparent K(m) for beta-3MG exchange transport is 19-fold greater than V(max)/apparent K(m) for alpha-3MG transport.

Survival of allochthonous bacteria in aquatic systems: a biological approach

The survival of allochthonous bacteria in aquatic systems is affected by biotic and abiotic environmental factors. Grazing by protozoa is one of the main biological processes that control allochthonous bacterial density. Its extent depends on the concentration of bacteria and the digestion capacity of the grazer. The physiological state of bacteria is affected by multiple physicochemical stresses, to which they respond by entering a dormant, viable but non-culturable state. Starved bacteria show a tendency to shrink, and a generally enhanced resistance to heat, oxidative and osmotic shock is observed. Nutrient scarcity, temperature, osmotic stress and visible light seem to be the abiotic factors that most negatively influence survival. The negative effect of light upon the culturability of enterobacteria in aquatic systems has long been recognized. In relation to the influence of plasmids on bacterial survival, heterogeneous and contradictory results have been reported. Some authors reported that plasmid-bearing strains can survive as well as their wild-type counterparts or even better, whereas in other reports the effects of various plasmids on the survival of their hosts were very variable. Plasmid transfer could be affected by the physiological status of donors and recipients during survival. Flow cytometry is a recent approach with great potential, especially for assessing the heterogeneity of cell size, metabolic state and molecular content in the population.

Initial diagnosis of anemia from sore mouth and improved classification of anemias by MCV and RDW in 30 patients

Thirty patients with a wide range of sore mouth that led to the diagnosis of iron deficiency in 12 patients, pernicious anemia in 8 patients, combined deficiency of iron and vitamin B12 in 2 patients, and anemia of chronic disease in 8 patients were investigated. The oral signs and symptoms included glossitis, glossodynia, angular cheilitis, recurrent oral ulcer, oral candidosis, diffuse erythematous mucositis, and pale oral mucosa. The values of hemoglobin in 30 patients varied from normal to severe life-threatening levels, but none had developed generalized symptoms sufficiently advanced to arouse suspicions of anemia before they visited the Oral Medicine Clinic. The aim of this paper is to describe a retrospective study of 30 patients with oral changes as the initial manifestation of nutritional deficiency or anemia of chronic diseases. Improved diagnosis and classification of anemia based on the mean and heterogeneity of red cell size will be discussed.

Neurosphere and neurosphere-forming cells: morphological and ultrastructural characterization

Despite recent advances in our understanding of neural stem cell (NSC) biology, the free-floating structures generated by these cells in vitro, the “neurospheres”, have not been fully characterized. To fill this gap, we examined neurospheres and neurosphere-derived NSCs by confocal microscopy, electron microscopy (EM) and cytofluorimetry. Here, we show that neurospheres and neurosphere-forming cells are morphologically and functionally heterogeneous. Confocal microscopy reveals differences in cell size, viability, cytoplasmic content and in the presence and distribution of active mitochondria. By electron microscopy, neurospheres appear as complex structures in which biological events such as mitosis, apoptosis and even phagocytosis are influenced by NSCs localization within the architecture of the neurosphere. NSCs derived from neurospheres are not synchronized and are represented in all phases of the cell cycle. Cytofluorimetric studies demonstrate NSCs' heterogeneity in cell size by forward scatter (FSC) analysis, and in cytoplasmic granularity by side scatter (SSC) profiling. These findings may contribute to our understanding of the morphogenesis of the neurospheres, particularly as this process relates to the high environmental adaptability of the NSCs and the reported existence of different subpopulations of neural stem cells.

Expression of apoptosis-related proteins and morphological changes in a rat tumor model of human small cell lung cancer prior to and after treatment with radiotherapy, carboplatin, or combined treatment.

In order to understand the apoptosis pathway in tumor cells, differences in cell morphology and expression of apoptosis-related proteins induced by radiation and/or chemotherapy, were investigated in a rat double tumor model comparing cisplatin-sensitive and -resistant human small cell lung cancer tumors. The cisplatin-sensitive human small cell lung cancer cell line (GLC4) and its cisplatin-resistant subline (GLC4-CDDP) were each injected subcutaneously in a different hind limb of the rat. After 15-17 days, radiation (10 Gy), carboplatin (25 mg/kg, intraperitoneal), combined treatment, or no treatment was administered. In combined treatment, carboplatin was administered 24 h before radiation. Tumors were removed and fixed 72 h after carboplatin or 48 h after radiation. Paraffin-embedded slides were stained with hematoxylin/eosin for morphology. Expression of the apoptosis-related proteins p53, p21, Rb, bcl-2, bax, c-myc, Fas and Fas-L was assessed immunohistochemically. In the GLC4 tumor, carboplatin treatment increased tumor cell size, tumor cell size heterogeneity, and number of apoptotic tumor cells. After radiation and combined treatment, these changes were more pronounced and multinuclear giant cells were observed. In GLC4-CDDP tumors, minimal changes were detected after carboplatin. Following radiation slight increases in tumor cell size, tumor cell size heterogeneity and number of apoptotic tumor cells were observed. No multinuclear giant cells were seen. After combined treatment, GLC4-CDDP showed cellular changes comparable to those in GLC4 cells after radiation or combined treatment, but no giant cells were observed. Untreated, both tumors were equally positive for p53, bax, Fas, Fas-L, c-myc and negative for Rb. Contrary to GLC4, untreated GLC4-CDDP tumors showed no p21 and bcl-2 expression. After combined treatment, an increase in number of bcl-2 positive cells was found in GLC4-CDDP tumors. No p21 was induced in GLC4-CDDP by any treatment modality. In GLC4 tumors, p21 was induced by radiation alone. No further changes in protein expression were induced by any treatment in GLC4 tumors. Following therapy, morphological changes in cell size and cell size heterogeneity were more pronounced in GLC4 than in GLC4-CDDP tumors. However, morphological changes in GLC4-CCDP tumors after treatment indicate that carboplatin plus radiotherapy may be effective also in cisplatin resistant tumor cells. An increase in p21 in GLC4 after radiation might facilitate apoptosis. The increase in number of Bcl-2 positive cells after combined treatment and the consistently negative p21 status after any treatment in GLC4-CDDP may protect these tumor cells from apoptosis as a part of their resistance mechanism to cisplatin.

Cell division and cell enlargement in isolated Cucurbita cotyledons grown in darkness and in light.

The spatial and temporal patterns of post-embryonal cell growth and cell division were characterised in excised cotyledons of vegetable marrow ( Cucurbita pepo L. var. giromontia Alef.) incubated in water. The concurrent roles of these two processes in cotyledon growth were determined using paradermal sections of the first palisade layer of developing cotyledons. Tissue specificity was observed in the pattern of cell division. The daughter cells derived from an initial cell, which had already differentiated before imbibition of the seeds, were tightly packed in a cluster, which enabled us to monitor cell division during early cotyledon development. Heterogeneity of cell size was recognised during the process of cell proliferation in the cluster, suggesting that cell division is uncoupled from control of cell size. There was significantly more cell division in the marginal part of the cotyledons than in other parts, suggesting high activity of the marginal meristem. Light enhanced cell and cotyledon enlargement, but had no effect on the number of divisions. This study elucidated the cellular basis of post-germinative Cucurbita cotyledon morphogenesis and development.

The adipose tissue phenotype of hormone-sensitive lipase deficiency in mice.

To directly ascertain the physiological roles in adipocytes of hormone-sensitive lipase (HSL; E.C. 3.1.1.3), a multifunctional hydrolase that can mediate triacylglycerol cleavage in adipocytes. We performed constitutive gene targeting of the mouse HSL gene (Lipe), subsequently studied the adipose tissue phenotype clinically and histologically, and measured lipolysis in isolated adipocytes. Homozygous HSL-/- mice have no detectable HSL peptide or cholesteryl esterase activity in adipose tissue, and heterozygous mice have intermediate levels with respect to wild-type and deficient littermates. HSL-deficient mice have normal body weight but reduced abdominal fat mass compared with normal littermates. Histologically, both white and brown adipose tissues in HSL-/- mice show marked heterogeneity in cell size, with markedly enlarged adipocytes juxtaposed to cells of normal morphology. In isolated HSL-/- adipocytes, lipolysis is not significantly increased by beta3-adrenergic stimulation, but under basal conditions in the absence of added catecholamines, the lipolytic rate of isolated HSL-/- adipocytes is at least as high as that of cells from normal controls. Cold tolerance during a 48-hour period at 4 degrees C was similar in HSL-/- mice and controls. Overnight fasting was well-tolerated clinically by HSL-/- mice, but after fasting, liver triglyceride content was significantly lower in HSL-/- mice compared with wild-type controls. In isolated fat cells, the lipolytic rate after beta-adrenergic stimulation is mainly dependent on HSL. However, the observation of a normal rate of lipolysis in unstimulated HSL-/- adipocytes suggests that HSL-independent lipolytic pathway(s) exist in fat. Physiologically, HSL deficiency in mice has a modest effect under normal fed conditions and is compatible with normal maintenance of core body temperature during cold stress. However, the lipolytic response to overnight fasting is subnormal.

Differences in regulation of pH(i) in large (>/=10 nuclei) and small (

Osteoclasts are multinucleated cells that resorb bone by extrusion of protons and proteolytic enzymes. They display marked heterogeneity in cell size, shape, and resorptive activity. Because high resorptive activity in vivo is associated with an increase in the average size of osteoclasts in areas of greater resorption and because of the importance of proton extrusion in resorption, we investigated whether the activity of the bafilomycin A(1)-sensitive vacuolar-type H(+)-ATPase (V-ATPase) and amiloride-sensitive Na(+)/H(+) exchanger differed between large and small osteoclasts. Osteoclasts were obtained from newborn rabbit bones, cultured on glass coverslips, and loaded with the pH-sensitive indicator 2', 7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF). Intracellular pH (pH(i)) was recorded in single osteoclasts by monitoring fluorescence. Large (>/=10 nuclei) and small (</=5 nuclei) osteoclasts differed in that large osteoclasts had a higher basal pH(i), their pH(i) was decreased by bafilomycin A(1) addition or removal of extracellular Na(+), and the realkalinization upon readdition of Na(+) was bafilomycin A(1) sensitive. After acid loading, a subpopulation of large osteoclasts (40%) recovered by V-ATPase activity alone, whereas all small osteoclasts recovered by Na(+)/H(+) exchanger activity. Interestingly, in 60% of the large osteoclasts, pH(i) recovery was mediated by both the Na(+)/H(+) exchanger and V-ATPase activity. Our results show a striking difference between pH(i) regulatory mechanisms of large and small osteoclasts that we hypothesize may be associated with differences in the potential resorptive activity of these cells.

Neuronal body size correlates with the number of nucleoli and Cajal bodies, and with the organization of the splicing machinery in rat trigeminal ganglion neurons.

Trigeminal ganglion neurons comprise three main cell body-size types. This cell size heterogeneity provides an excellent neuronal model to study the cell size-dependent organization and dynamics of the nucleoli, Cajal (coiled) bodies (CBs), and nuclear speckles of pre-mRNA splicing factors, nuclear structures that play a key role in the normal neuronal physiology. We have analyzed the number of nucleoli and CBs and the structural and molecular organization of CBs and nuclear speckles in the three neuronal types by using immunofluorescence with antibodies that recognize nucleoli (fibrillarin), CBs (coilin), and nuclear speckles (snRNPs), confocal microscopy, and electron microscopy. Whereas the mean number of nucleoli per neuron decreases as a function of cell size, the number of CBs per cell significantly increases in large neurons in comparison with the small ones. In addition, large neurons have a higher proportion of CBs associated with the nucleolus. In all neuronal types, CBs concentrate coilin, fibrillarin, snRNPs, and the survival motor neuron protein (SMN). Immunostaining for snRNPs shows small speckle domains and extensive areas of diffuse nucleoplasmic signal in large neurons, in contrast with the large nuclear speckles found in small neurons. Furthermore, flow cytometric analysis shows that all neurons are in the range of diploid cells. These findings indicate that the fusion behavior of nucleoli, the formation of CBs and their relationships with the nucleolus, as well as the compartmentalization of the pre-mRNA splicing machinery, is related to cell body size in the trigeminal ganglion neurons. Because transcriptional activity is a basic determinant mechanism of cell size in diploid cells, we suggest that our findings reflect a distinct transcription-dependent organization of the nucleolus and splicing machinery in the three cell types of trigeminal ganglion neurons.

Escherichia colilipopolysaccharide effects on proliferating rat liver cells in culture: a morphological and functional study

Liver cells have been implicated in playing an important role in the pathogenesis of endotoxic shock-associated liver injury. The present study was designed to investigateEscherichia coli0111:B4 lipopolysaccharide (LPS) effects on proliferating rat liver cells in culture. Isolated cell system can rarely serve as models of complete organisms, but with using an in vitro test-model, endogenic factors (e.g. hormonal effects, nervous influences, blood activation, etc.) or experimental stress in laboratory animals can be eliminated as variables affecting hepatocellular responses. In the proposed in vitro model, using specially proliferating liver cells, morphological cell alterations were observed after 30 min and low doses endotoxin administration (10 μg/ml). LPS induced an extreme fragility and a diminished adhesion capacity on cells. Cell-to-cell contacts were also disturbed. The LPS treatment produced extreme heterogeneity in liver cell size, enlargement of nuclei, nuclear and cytoplasmic protrusions, and increased the number of large nucleoli and lipid droplets, also decreasing the angiotensin action on intracellular calcium levels. The effects observed after the LPS exposition can be related with an altered metabolism of the liver cells in culture due to a destabilization of plasma membrane, a transmembrane signalling alteration, and a mitochondrial damage. The specificity of cell response to endotoxic lipopolysaccharide suggests a multiple membrane damage inducing important metabolic disturbances.

Cell Counting

AbstractThis unit presents protocols for counting cells using either a hemacytometer or electronically using a Coulter counter. Cell counting with a hemacytometer permits effective discrimination of live from dead cells using trypan blue exclusion. In addition, the procedure is less subject to errors arising from cell clumping or size heterogeneity. Counting cells is more quickly and easily performed using an electronic counter, but live‐dead discrimination is unreliable. Cell populations containing large numbers of dead cells and/or cell clumps are difficult to count accurately. In addition, electronic counting requires resetting of the instrument for cell populations of different sizes; heterogeneous populations can give rise to inaccurate counts, and resting and activated cells may require counting at separate settings. In general, electronic cell counting is best performed on fresh peripheral blood cells.

Monitoring Cell Growth

This appendix provides two protocols for monitoring cell growth. Counting cells using a hemacytometer is tedious but it allows one to effectively distinguish live cells from dead cells (using Trypan Blue exclusion). In addition, this procedure is less subject to errors due to cell clumping or heterogeneity of cell size. The use of an electronic cell counter is quicker and easier than counting cells using a hemacytometer. However, an electronic cell counter as currently constructed does not distinguish live from dead cells in a reliable fashion and is subject to error due to the presence of cell clumps. Overall, the electronic cell counter is best reserved for repetitive and rapid counting of fresh peripheral blood cells and should be used with caution when counting cell populations derived from tissues.

Older adults' expectations about mental health counseling: a multivariate and discriminant analysis.

The present study aimed at identifying significant predictors of expectations about mental health counseling in a sample of highly educated elderly. This task was achieved by administering the full version of the Expectations About Counseling (EAC) questionnaire to fifty-seven retired professors. We first addressed the issue of the current elderly's under-utilization of formal counseling services, then conducted a literature review on the relationship between elderly's characteristics and their views of counseling. Specific hypotheses were formulated for each of the seven possible predictors of EAC scale scores. Previous counseling experience and marital status were significant predictors of EAC scale scores. Young-old adults (i.e., younger than 75 years of age) had received counseling experience significantly more than their older counterpart; their EAC scores, however, were not significantly different than those of old-old participants. Gender, area of residence, income and religiosity did not predict expectations about counseling significantly. Cell size heterogeneity for some predictors might have been responsible for lack of significance on additional factors. The article ends with a discussion of several clinical implications of the findings.

Characterization of TPM1 disrupted yeast cells indicates an involvement of tropomyosin in directed vesicular transport.

Disruption of the yeast tropomyosin gene TPM1 results in the apparent loss of actin cables from the cytoskeleton (Liu, H., and A. Bretscher. 1989. Cell. 57:233-242). Here we show that TPM1 disrupted cells grow slowly, show heterogeneity in cell size, have delocalized deposition of chitin, and mate poorly because of defects in both shmooing and cell fusion. The transit time of alpha-factor induced a-agglutinin secretion to the cell surface is longer than in isogenic wild-type strains, and some of the protein is mislocalized. Many of the TPM1-deleted cells contain abundant vesicles, similar in morphology to late secretory vesicles, but without an abnormal accumulation of intermediates in the delivery of either carboxypeptidase Y to the vacuole or invertase to the cell surface. Combinations of the TPM1 disruption with sec13 or sec18 mutations, which affect early steps in the secretory pathway, block vesicle accumulation, while combinations with sec1, sec4 or sec6 mutations, which affect a late step in the secretory pathway, have no effect on the vesicle accumulation. The phenotype of the TPM1 disrupted cells is very similar to that of a conditional mutation in the MYO2 gene, which encodes a myosin-like protein (Johnston, G. C., J. A. Prendergast, and R. A. Singer. 1991. J. Cell Biol. 113:539-551). The myo2-66 conditional mutation shows synthetic lethality with the TPM1 disruption, indicating that the MYO2 and TPM1 gene products may be involved in the same, or parallel function. We conclude that tropomyosin, and by inference actin cables, may facilitate directed vesicular transport of components to the correct location on the cell surface.

Flow cytometric analysis of granulosa cells from developing rat follicles

Immature rats were treated with diethylstilboestrol (DES) or pregnant mares' serum gonadotropin (PMSG) and forward angle light-scatter (FALS) and 90 degrees light-scatter (90 degrees LS) signals were used to measure the size and the granularity (internal organization) of the granulosa cells, respectively. The results confirmed the presence of two major populations of granulosa cells in the ovaries of both groups of rats, with the same percentage of larger cells in both treatments (52.3% in DES, 49.5% in PMSG). Since DES treatment brings about granulosa cell growth while PMSG treatment causes growth and differentiation, it is evident that there is heterogeneity in granulosa cell sizes during different states of growth and differentiation. There was also heterogeneity in sizes of granulosa cells harvested from follicles of small (less than 210 microns), medium (210-420 microns) and large (greater than 420 microns) diameter. Quadrant analysis of granulosa cells in various fractions collected from Percoll gradients suggested an increase in granularity in the small and large granulosa cell populations. Cell cycle analysis of small and large granulosa cell populations collected from large follicles of rats treated with PMSG indicated that each population was distributed in G0/G1, S and G2/M phases. These results demonstrate that populations of small and large granulosa cells exist in rat ovarian follicles during various stages of growth and differentiation.

Acute effects of human growth hormone on liver cells in vitro: A comparison with livers of mice transgenic for human growth hormone

We have examined the effects of human growth hormone (hGH), in concentrations comparable to those measured in plasma of transgenic mice expressing foreign GHs, on rat liver cells in culture. This treatment produced, within 24 and 48 hr, extreme heterogeneity in liver cell size, enlargement of nuclei, increase in the numbers of large nucleoli and nuclear protrusions, as well as appearance of numerous lipid droplets and accumulation of glycogen. These changes most likely indicate massive metabolic alterations and resemble changes present in vivo in the livers of mice transgenic for hGH and other foreign GHs. Since morphological alterations in vitro were apparent within 24 hr, we conclude that GH acutely and directly affects liver cell morphology and function in vitro and that the pathological lesions in vivo in the livers of transgenic mice are very likely a consequence of GH action.