Medicare home health cost ceilings increased substantially.
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Costs and Cost Analysis↗
Biomedical subjects
P Grimaldi
Publications and source records attributed to P Grimaldi.
Expression of the mRNA for the ligand of c-kit in mouse Sertoli cells.
The expression of the mRNA for SLF (the c-kit ligand), a product of the "steel" locus, has been investigated in postnatal mouse testis and homogeneous populations of testicular cells. The message was found expressed in postnatal mouse testis but not in germ cells. Studies on primary mouse Sertoli cell cultures from 18 day old mice show that Sertoli cells are the site of SLF mRNA expression in the seminiferous tubules. Treatment of Sertoli cell cultures with cAMP analogs led to a significant increase in the SLF mRNA levels.
Animals↗
PPS for operating and capital costs.
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Capital Expenditures↗
Peptides from chiral C alpha,alpha-disubstituted glycines. Synthesis and characterization, conformational energy computations and solution conformational analysis of C alpha-methyl, C alpha-isopropylglycine [(alpha Me)Val] derivatives and model peptides.
Conformational energy computations on Ac-L-(alpha Me)Val-NHMe indicate that turns and right-handed helical structures are particularly stable conformations for this chiral C alpha-methyl, C alpha-alkylglycyl residue. We have synthesized and characterized a variety of L-(alpha Me)Val derivatives and peptides (to the pentamer level). The results of the solution conformational analysis, performed using infrared absorption, 1H nuclear magnetic resonance, and circular dichroism, are in general agreement with those obtained from the theoretical investigation, in the sense that the L-(alpha Me)Val residue turns out to be a strong beta-turn and right-handed helix former. A comparison is also made with the conclusions extracted from published work on peptides rich in other C alpha-methyl, C alpha-alkylglycyl residues.
Circular Dichroism↗
Regulation of adipose cell differentiation. I. Fatty acids are inducers of the aP2 gene expression.
The regulation of the expression of adipose-related genes, i.e., aP2, adipsin, and glycerophosphate dehydrogenase (GPDH) by growth hormone (GH) and polyamines, as well as the role of fatty acids, have been investigated in polyamine-dependent Ob1754 cells and Ob1771 preadipose cells. Growth hormone acts as an obligatory hormone for adipsin and GPDH gene expression but its presence is not required for the expression of the aP2 gene. In fully differentiated Ob1771 cells, impairment of fatty acid synthesis by glucose deprivation leads to an inhibition of the aP2 gene expression, whereas the expression of adipsin and GPDH genes remains unaffected. Supplementation of the culture medium with fatty acids prevents the decrease of aP2 gene expression, and this effect appears primarily due to an increase in the transcriptional level of aP2 gene. The induction of aP2 gene has been examined in early committed, lipid-free Ob1771 cells in which fatty acid synthesis is very low despite glucose supplementation. Long-chain fatty acids (greater than or equal to C12) are able to activate the aP2 gene. It is concluded that fatty acids or fatty acid metabolites activate the aP2 gene and subsequently modulate its expression.
Adipose Tissue↗
Regulation of adipose cell differentiation. II. Kinetics of induction of the aP2 gene by fatty acids and modulation by dexamethasone.
Fatty acids behave as activators of the aP2 gene expression in committed, lipid-free, non-terminally differentiated Ob1771 cells. Like fatty acids, dexamethasone provokes a dose-dependent accumulation of aP2 mRNA. However, fatty acids and dexamethasone act through different mechanisms to activate the aP2 gene expression since i) fatty acids and dexamethasone act in a synergistic manner; ii) the effect of dexamethasone is rapid and transient (maximal effect after 8 h), whereas that of fatty acids is slower, and maintained as long as the inducer is present and is fully reversible upon fatty acid removal; iii) the induction of the aP2 gene expression by dexamethasone does not require ongoing protein synthesis, while the response to fatty acids is completely prevented by cycloheximide; and iv) the induction of the aP2 gene expression by fatty acids but not by dexamethasone is confined to preadipocyte cell lines. This suggests that the process of activation by fatty acids, rather than the expression of the aP2 gene, is unique to adipose cells. Besides their effects on the aP2 gene, fatty acids activate the expression of the acyl CoA synthetase gene which encodes another protein involved in fatty acid metabolism. Activation of both genes by fatty acids appears not to be mediated by the CCAAT enhancer binding protein, a nuclear factor reported as transactivator of the aP2 promoter activity, since the enhancer binding protein mRNA is not expressed under these conditions.
Adipose Tissue↗
Expression and regulation of pOb24 and lipoprotein lipase genes during adipose conversion.
Lipoprotein lipase (LPL) and pOb24 mRNAs are known to be early markers of adipose cell differentiation. Comparative studies of the expression of pOb24 and LPL genes during adipose conversion of Ob1771 preadipocyte cells and in mouse adipose tissue have shown the following: 1) the expression of both genes takes place at confluence; this event can also be triggered by growth arrest of exponentially growing cells at the G1/S stage of the cell cycle; 2) In contrast to glycerol-3-phosphate dehydrogenase mRNA, the emergence of pOb24 and lipoprotein lipase mRNAs requires neither growth hormone or tri-iodothyronine as obligatory hormones nor insulin as a modulating hormone; 3) in mouse adipose tissue, pOb24 mRNA is present at a high level in stromal-vascular cells and at a low level in mature adipocytes, and in contrast LPL mRNAs are preferentially expressed in mature adipocytes. Thus, these two genes do not appear to be regulated in a similar manner, as also shown by the differential inhibition of their expression by tumor necrosis factor (TNF) and transforming growth factor-beta (TGF-beta).
Adipose Tissue↗
Follicle-stimulating hormone and cyclic AMP induce transcription from the human urokinase promoter in primary cultures of mouse Sertoli cells.
The hormonal regulation of the human urokinase type plasminogen activator (uPA) gene has been studied by introducing into mouse and rat Sertoli cell primary cultures a recombinant plasmid, in which the transcription regulatory elements of the cloned human uPA gene drive the expression of the bacterial chloramphenicol-acetyl-transferase gene. It was found to be expressed and regulated by FSH and (Bu)2cAMP in the mouse cells only, in agreement with data on the expression of the endogenous gene in rat and mouse gonads. The stimulation of transcription by FSH was evident in cultures from 13-day-old but not from 18-day-old mice, even though (Bu)2cAMP induction could be observed at both ages. Phorbol-myristate acetate was found to activate the human uPA promoter in Sertoli cell cultures from mice of both ages, even though the effect was less evident in cultures of 18-day-old animals. Deletion analysis of the human uPA 5'-flanking region showed that the distal enhancer element is not needed for (Bu)2cAMP induction, and that at least two promoter regions are involved in (Bu)2cAMP induced transcription. One of these cAMP responsive regions lies between nucleotides -72 and -29 from the CAP site. The sequence of this region would suggest the binding of transcription factor AP-2, a cell-specific mediator of both cAMP and phorbol esters action on gene expression. However, these sequences do not mediate phorbol ester activation of human uPA promoter in mouse Sertoli cells.
Animals↗
[Gene expression regulation of adipocyte differentiation: cell cycle and hormones].
The adipose conversion of cultured preadipose cells involves the activation of numerous genes and is controlled by various adipogenic and mitogenic factors. The differentiation program can be divided into early and late events. Early events are triggered by growth arrest at the G1/S boundary and characterized by the activation of a set of genes (pOb24, lipoprotein lipase, etc.). The expression of the terminal differentiation-related genes takes place after a limited growth resumption of early markers containing cells and requires the presence of permissive hormones (growth hormone and triiodothyronine). Insulin acts solely as a modulator in the expression of the terminal differentiation-related genes. In vivo studies suggest that the acquisition of new adipocytes might result from terminal differentiation of dormant, already committed (pOb24 positive) cells when exposed to appropriate mitogenic or adipogenic stimuli.
Adipose Tissue↗
Cloning and regulation of a mRNA specifically expressed in the preadipose state.
A cDNA library of Ob1771 preadipocytes was constructed, and a cDNA clone designated pOb24 was isolated by differential screening. The pOb24 mRNA, 6 kilobases in length, rose sharply in early differentiating Ob1771 and 3T3-F442A cells and decreased thereafter. In mouse adipose tissue, it was present at a high level in stromal-vascular cells (containing adipose precursor cells) and at a low level in mature adipocytes. Thus, pOb24 mRNA appears to be both in vitro and in vivo an unique marker of the preadipose state, i.e. of cell commitment during adipose cell differentiation. In contrast to glycerol-3-phosphate dehydrogenase mRNA, the emergence of pOb24 mRNA in Ob1771 cells required neither growth hormone or triiodothyronine as obligatory hormones nor insulin as a modulating hormone. Comparative studies of the expression of pOb24 and dihydrofolate reductase genes during the cell cycle suggest that arrest at the G1/S boundary was critical for the entry into the preadipose state. Tumor necrosis factor and transforming growth factor-beta were able to induce a large decrease of pOb24 mRNA level in growth-arrested Ob1771 cells. This decrease was shown to be only confined to early differentiating, glycerol-3-phosphate dehydrogenase negative cells as no decrease of pOb24 mRNA level was observed in glycerol-3-phosphate dehydrogenase positive cells. This result suggests that signals generated by tumor necrosis factor and transforming growth factor-beta have no effect on a commitment-related gene in late differentiated cells.
Adipose Tissue↗
Thermal properties of young red blood cells are indicative of an age-dependent regulation of membrane-skeleton interaction.
The effects of red blood cell (RBC) age on membrane thermal properties have been investigated by using a 16-nitroxide stearic acid spin probe. We detected in unfractionated and most dense cells (2% fraction of circulating cells) a thermal transition at 40 degrees C that in young cells (1% fraction) was lowered at 33-35 degrees C. Spectrin seems to be directly involved in the transition detected in both young and unfractionated cells, as showed by the disappearance of the breaks after low salt extraction of spectrin. A further indication for a role of spectrin in this transition comes from its characteristic thermal unfolding above 40 degrees C. However, young cells did not show changes either in the thermal unfolding of spectrin or in the distribution of spectrin dimer, tetramer, and high oligomeric forms. These data rule out that spectrin of young RBC is modified in its thermal properties and indicate that young cells may have a different spectrin-membrane interaction. Treatment of unfractionated ghosts with an antibody specific for a fragment of the 10K domain of protein 4.1, which is fully competent for the spectrin-actin binding, produced an evident lowering of the transition temperature. The same antibody did not affect the thermal transition of young ghosts. Our results suggest that spectrin-membrane interactions may be regulated during RBC lifespan.
Aging↗
Regulation of gene expression by insulin in adipose cells: opposite effects on adipsin and glycerophosphate dehydrogenase genes.
Insulin is known to play the role of a positive effector both in vitro on the adipose conversion process and in vivo on the fatty acid synthesis and esterification processes in adipose tissue. The effects of insulin on the expression of two genes activated during adipose conversion, glycerol-3-phosphate dehydrogenase (GPDH) and adipsin genes, have been investigated in 3T3 F442A adipose cells. Within a physiological range of concentrations, insulin exerts opposite effects on the levels of GPDH (EC50 approximately 0.2 nM) and adipsin (EC50 approximately 1 nM) mRNAs. Its negative effect on the abundance of adipsin mRNA involves primarily a rapid inhibition of the transcriptional rate (less than 2 h). Its positive effect on the abundance of GPDH mRNA is due to a stimulation of the transcriptional rate accompanied by a delayed stabilization of GPDH mRNA. In addition, insulin exerts a specific effect on the length of the poly(A) tract of the adipsin mRNA. These results show that a single mechanism for the regulation of adipose-related genes by insulin can be excluded but rather suggest a complex phenomenon in which various levels of regulation take place.
Adipose Tissue↗
Growth hormone stimulates c-fos gene expression by means of protein kinase C without increasing inositol lipid turnover.
Growth hormone (GH) is required for the terminal differentiation of preadipose Ob1771 cells that have entered the differentiation program as evidenced by the expression of early marker genes (pOb24 and lipoprotein lipase). Induction of c-fos mRNA within 15 min and induction of insulin-like growth factor I mRNA within a few hours take place in response to GH. The role of GH is mediated, at least in part, by means of the activation of protein kinase C, as shown by the inhibition of epidermal growth factor binding and by the expression of the c-fos gene, and is thus analogous to the action of prostaglandin F2 alpha and 4 beta-phorbol-12,13-didecanoate in this respect. However, in contrast to that of the c-fos gene, the regulation of insulin-like growth factor I gene expression by GH is not mediated by means of the activation of protein kinase C, and, in line with this, prostaglandin F2 alpha and 4 beta-phorbol-12,13-didecanoate were ineffective. GH and prostaglandin F2 alpha were able to stimulate the formation of diacyglycerol within a few seconds, but GH did not elicit an accumulation of inositol phosphates, in contrast to that generated by prostaglandin F2 alpha. We conclude that the transduction signal of GH action in c-fos mRNA induction is the formation of diacylglycerol and that the mechanism whereby GH can activate protein kinase C is associated with a phospholipase C-mediated hydrolysis of glycerophospholipids other than inositol phospholipids.
Animals↗
Coupling growth arrest and adipocyte differentiation.
The complete differentiation program of preadipose cells can be divided into early and late events. The expression of early markers takes place at growth arrest (G1/S boundary), whereas that of late markers, leading to terminal differentiation, takes place after a limited number of mitoses of early marker-containing cells. Only terminal differentiation requires the presence of growth hormone and triiodothyronine and results in the formation of triacylglycerol-filled, nondividing cells. The events of adipose cell differentiation which take place in vitro allow a better understanding of the development of adipose tissue in vivo.
Adipose Tissue↗
HDL receptor and reverse cholesterol transport in adipose cells.
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Adipose Tissue↗
Interactions of skeletal proteins with red blood cell membrane.
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Cytoskeletal Proteins↗
Acute regulation of insulin-like growth factor-I gene expression by growth hormone during adipose cell differentiation.
Insulin-like growth factor I (IGF-I) is a mitogenic polypeptide that is thought to play, under the control of growth hormone, a role in fetal development as well as post-natally. The direct effect of growth hormone on the regulation of the expression of IGF-I gene was examined in adipose Ob1771 cells. Growth hormone regulates the abundance of multiple species of IGF-I mRNAs of 15, 7.5, 1.5 and 0.8 kb in a differentiation-dependent manner. The regulation of IGF-I gene expression is strikingly rapid (less than 2 h), reversible and takes place primarily at transcriptional level. Thus growth hormone can increase the cellular content of IGF-I mRNA encoding for a protein which could be involved in a paracrine/autocrine action during adipose tissue development.
Adipose Tissue↗
Relationship in adipose cells between the presence of receptor sites for high density lipoproteins and the promotion of reverse cholesterol transport.
The role of a high-affinity receptor site for high-density lipoproteins (HDL) has been investigated in parental Ob1771 adipose cells and their transformed counterparts after transfer of the complete early region of polyoma virus (Ob17PY cells). Binding of ApoAI, ApoAII and HDL3 occurs in Ob1771 cells and derived membranes, whereas no binding is observed in Ob17PY cells and derived membranes. After thymidine block, growth-arrested Ob17PY cells become able to bind ApoAI, ApoAII and HDL3; this recovery is prevented in actinomycin D- or cycloheximide-treated cells. In contrast to ApoAI, ApoAII or HDL3 binding, both growing and growth-arrested Ob17PY cells do show receptor activities for low density lipoproteins and transferrin, respectively, which are similar in affinity and maximal capacity. Following cholesterol accumulation which takes place in the presence of LDL cholesterol, subsequent exposure to HDL3 or ApoAI promotes cholesterol efflux from Ob1771 cells and growth-arrested Ob17PY cells but not from growing Ob17PY cells. These results show that the presence of a high-affinity receptor site for HDL in intact adipose cells is required for the promotion of reverse cholesterol transport.
Adipose Tissue↗