RGS5, RGS4, and RGS2 expression and aortic contractibility are dynamically co-regulated during aortic banding-induced hypertrophy

Overexpression of regulator of G protein signaling 5 (RGS5) in arteries over veins is the most striking difference observed using microarray analysis. The obvious question is what arterial function might require RGS5. Based on functions of homologous proteins in regulating cardiac mass and G-protein-coupled receptor (GPCR) signaling, we proposed that RGS5 and vascular expressed RGS2 and RGS4 could participate in regulating arterial hypertrophy. We used the suprarenal abdominal aorta banding model to induce hypertension and hypertrophy. All 3 RGS messages were expressed in unmanipulated aorta with RGS5 predominating. After 2 days, thoracic aorta lost expression of RGS5, 4, and 2. At 1 week, all three returned to normal, and at 28 days, they increased many fold above normal. Valsartan blockade of angiotensin II (angII)/angII type 1 receptor signaling prevented upregulation of RGS messages but only delayed mass increases, implying wall mass regulation involves both angII-dependent and angII-independent pathways. The abdominal aorta showed less dramatic expression changes in RGS5 and 4, but not 2. Again, those changes were delayed by valsartan treatment with no mass changes. Thoracic aorta contraction to GPCR agonists was examined in aortic explant rings to identify vessel wall physiological changes. In 2-day aorta, the response to Galphaq/i agonists increased above normal, while 28-day aorta had attenuated induced contraction via Galphaq/i agonist, implicating a connection between RGS message levels and changes in GPCR-induced contraction. In vitro overexpression studies showed RGS5 inhibits angII-induced signaling in smooth muscle cells. This study is the first experimental evidence that changes in RGS expression and function correlate with vascular remodeling.

Expression profiling identifies smooth muscle cell diversity within human intima and plaque fibrous cap: loss of RGS5 distinguishes the cap

BACKGROUND

The fibrous cap of the atherosclerotic lesion is believed to be critical to stability because disruption of the cap is the final event leading to plaque rupture. We have, therefore, used expression arrays to define the phenotype of the cap and other plaque components.

METHODS AND RESULTS

To identify unique expression programs able to distinguish the smooth muscle of the cap from other plaque smooth muscle cells, RNA profiles were determined in human carotid artery media, nonatherosclerotic adjacent intima, fibrous cap of advanced atherosclerotic plaques, and whole advanced plaque with cDNA arrays covering 21,000 or 26,000 Unigene clusters. The molecular signature of each tissue was dominated by a core gene-set with differential expression of <1% of clusters assayed.

CONCLUSIONS

Both intima and cap expressed novel genes not previously associated with SMC pathology. If the cap is derived from a unique subpopulation, this pattern is the signature of that particular set of cells. The loss of RGS5 in the fibrous cap is of particular interest because of its role in vessel development and physiology.

Regulator of G protein signaling 5 marks peripheral arterial smooth muscle cells and is downregulated in atherosclerotic plaque

OBJECTIVE

Regulator of G protein signaling 5 (RGS5), an inhibitor of Galpha(q) and Galpha(i) activation, was recently identified among genes highly expressed in smooth muscle cells (SMCs) of aorta but not vena cava. This finding prompted the hypothesis that RGS5 provides long-term G protein inhibition specific to normal arterial SMC populations and that loss of expression may in turn contribute to arterial disease.

METHODS

To test this hypothesis we characterized RGS5 gene expression throughout the vasculature of nonhuman primates to determine whether RGS5 was restricted to arteries in other vascular beds and whether expression was altered in arterial disease.

RESULTS

In situ hybridization localized RGS5 message to medial SMCs of peripheral arteries, including carotid, iliac, mammary, and renal arteries, but not accompanying veins. SMCs of many small arteries and arterioles also expressed RGS5, including glomerular afferent arterioles critical to blood pressure regulation. Differential expression persisted in culture, inasmuch as RGS5 message was significantly higher in SMCs derived from arteries than from veins at real-time polymerase chain reaction. It was remarkable that the only major arterial bed lacking RGS5 was the coronary circulation. In atherosclerotic peripheral arteries RGS5 was expressed in medial SMCs, but was sharply downregulated in plaque SMCs.

CONCLUSION

These data identify RGS5 as a new member of a short list of genes uniquely expressed in peripheral arteries but not coronary arteries. Persistence of an arterial pattern of RGS5 expression in culture and lack of expression in coronary arteries support a unique SMC phenotype fixed by distinct lineage or differentiation pathways. The association between loss of expression and arterial wall disease has prompted the new hypothesis that prolonged inhibition by RGS5 of vasoactive or trophic G protein signaling is critical to normal peripheral artery function.

Vascular failure: a hypothesis

Although cardiac failure has been studied extensively, vascular failure is not a recognizable term. We suggest that it is reasonable to argue that failure of the vessel to control its mass, contractile capacity, and lumen will involve pathways similar to cardiac failure. Vascular failure, or perhaps more accurately arterial failure, has very different consequences. Failure to control mass and external diameter will result in hypertension or loss of lumen in atherosclerosis. We review what is known about this normal remodeling response and its failure, and propose directions for research.

Suppression subtractive hybridization identifies distinctive expression markers for coronary and internal mammary arteries

OBJECTIVE

We sought to identify differentially expressed genes in the athero-prone coronary artery and athero-resistant internal mammary arteries.

METHODS AND RESULTS

Using suppressive subtraction hybridization, we generated reciprocal cDNA collections of representative mRNAs specific to porcine coronary arteries versus porcine mammary arteries. We screened 1000 suppressive subtraction hybridization cDNA clones by dot blot array and sequenced 600 of those showing the most marked expression differences. Northern blot, in situ hybridization, and immunostaining confirmed the differential gene expression patterns identified by the dot blot arrays. Genes associated with mammary arteries included claudin-10 and h-cadherin, which are genes associated with tight junctions and intermediate junctions. In contrast, genes associated with proatherosclerotic processes, such as lipid retention and metabolism, inflammation, and cell growth, were preferentially expressed in coronary arteries.

CONCLUSIONS

Normal coronary arteries have gene expression program that is significantly different than internal mammary arteries. These differences may partly explain the resistance of coronary arteries and internal mammary arteries to atherosclerosis.

Expression profiling identifies 147 genes contributing to a unique primate neointimal smooth muscle cell phenotype

OBJECTIVE

This study represents the first in an effort to systematically characterize different intimas by using expression array analysis.

METHODS AND RESULTS

We compared smooth muscle cells (SMCs) of the neointima formed 4 weeks after aortic grafting with those from normal aorta and vena cava from cynomolgus monkeys. Hybridization to cDNA arrays identified subsets of 147 and 45 genes differentially expressed in the neointima versus the aorta and vena cava, respectively. The expression pattern differentiating neointima from aortic SMCs was characterized largely by suppression. Only 13 genes were induced in the neointima: 7 encoded matrix proteins (6 collagens and 1 versican) and 2 encoded inducers of matrix synthesis (osteoblast-specific factor-2/Cbfa1 and connective tissue growth factor). The genes suppressed most in the neointima included the regulator of G-protein signaling-5, SPARClike-1/hevin, and nonmuscle myosin heavy chain-B. A smaller gene set differentiated the neointima from the vena cava. Most were induced (39 of 45 genes), and overlap with the neointima-aorta set was significant (10 of 13 genes). Array results were validated with Northern analysis, in situ hybridization, or immunohistochemistry.

CONCLUSIONS

These data underscore the importance of matrix synthesis in neointimal maturation, and novel genes, newly associated with neointimal SMCs (regulator of G-protein signaling-5 and osteoblast-specific factor-2/Cbfa1), have raised new hypotheses regarding the pathogenesis of intimal hyperplasia.

Open-label randomized trial of torsemide compared with furosemide therapy for patients with heart failure

PURPOSE

Because the bioavailability of oral furosemide is erratic and often incomplete, we tested the hypothesis that patients with heart failure who were treated with torsemide, a predictably absorbed diuretic, would have more favorable clinical outcomes than would those treated with furosemide.

PATIENTS AND METHODS

We conducted an open-label trial of 234 patients with chronic heart failure (mean [+/- SD] age, 64 +/- 11 years) from an urban public health care system. Patients received oral torsemide (n = 113) or furosemide (n = 121) for 1 year. The primary endpoint was readmission to the hospital for heart failure. Secondary endpoints included readmission for all cardiovascular causes and for all causes, numbers of hospital days, and health-related quality of life.

RESULTS

Compared with furosemide-treated patients, torsemide-treated patients were less likely to need readmission for heart failure (39 [32%] vs. 19 [17%], P <0.01) or for all cardiovascular causes (71 [59%] vs. 50 [44%], P = 0.03). There was no difference in the rate of admissions for all causes (92 [76%] vs. 80 [71%], P = 0.36). Patients treated with torsemide had significantly fewer hospital days for heart failure (106 vs. 296 days, P = 0.02). Improvements in dyspnea and fatigue scores from baseline were greater among patients treated with torsemide, but the differences were statistically significant only for fatigue scores at months 2, 8, and 12.

CONCLUSIONS

Compared with furosemide-treated patients, torsemide-treated patients were less likely to be readmitted for heart failure and for all cardiovascular causes, and were less fatigued. If our results are confirmed by blinded trials, torsemide may be the preferred loop diuretic for patients with chronic heart failure.

A comparison of aorta and vena cava medial message expression by cDNA array analysis identifies a set of 68 consistently differentially expressed genes, all in aortic media

We performed a systematic analysis of gene expression in arteries and veins by comparing message profiles of macaque aorta and vena cava media using a cDNA array containing 4048 known human genes, approximately 35% of currently named human genes (approximately 11,000). The data show extensive differences in RNA expression in artery versus vein media. Sixty-eight genes had consistent elevation in message expression by the aorta, but none were elevated in the vena cava. The most differentially expressed gene was regulator of G-protein signaling (RGS) 5, at an expression ratio of 46.5+/-12.6 (mean+/-SEM). The data set also contained 2 genes already known to be expressed in the aorta, elastin at 5.0+/-1.4, and the aortic preferentially expressed gene 1 (APEG-1) at 2.3+/-0.6. We chose to analyze RGS5 expression further because of its high level of differential expression in the aorta. Levels of RGS5 mRNA were confirmed by Northern analysis and in situ hybridization. A human tissue RNA dot blot showed that RGS5 message is highest in aorta, followed by small intestine, stomach, and then heart. Northern analysis confirmed that RGS5 expression in human aorta is higher than in any region of the heart. RGS5 is a G-protein signaling regulator of unknown specificity most homologous to RGS4, an inhibitory regulator of pressure-induced cardiac hypertrophy. The expression pattern of the 68 differential genes as a whole is a start toward identifying the molecular phenotypes of arteries and veins on a systematic basis.

Plasminogen activator inhibitor type-1 and interleukin-6 in haemolytic uraemic syndrome

OBJECTIVE

Because haemolytic uraemic syndrome (HUS) is an important cause of renal dysfunction in children, the availability of prognostic markers of disease severity could assist in identifying those at risk of developing long-term sequelae. The aim of this study was to test the hypothesis that plasma levels of plasminogen activator inhibitor type-1 (PAI-1) and interleukin-6 (IL-6) in children at the time of diagnosis of HUS would predict renal function outcome in terms of glomerular filtration rate (GFR).

METHODOLOGY

Fourteen children suffering from diarrhoeal HUS were studied. Plasma samples were assayed for PAI-1 and IL-6, and GFR was measured at intervals after discharge from hospital. Twelve months following their recovery from HUS, the children were allocated to one of two outcome groups depending on whether GFR was above (Good Outcome, n = 9), or below (Poor Outcome, n = 5) 80 mL/min per 1.73 m2.

RESULTS

Elevated concentrations of PAI-1 were found in 4 of 5 Poor Outcome and 4 of 9 Good Outcome children. At the same time, increased concentrations of IL-6 were observed in 3 of 5 Poor Outcome and 3 of 9 Good Outcome children. Renal function continued to be compromised in four Poor Outcome children 36 months after diagnosis.

CONCLUSIONS

Our data show that PAI-1 and IL-6 are elevated in the plasma of some children at the time of diagnosis of HUS, but that neither is a definitive prognostic marker of poor outcome 3 years later.

Fas/FADD-mediated activation of a specific program of inflammatory gene expression in vascular smooth muscle cells

Apoptosis of smooth muscle cells is a common feature of vascular lesions but its pathophysiological significance is not known. We demonstrate that signals initiated by regulated Fas-associated death domain protein overexpression in rat vascular smooth muscle cells in the carotid artery induce expression of monocyte-chemoattractant protein-1 and interleukin-8, and cause massive immigration of macrophages in vivo. These chemokines, and a specific set of other pro-inflammatory genes, are also upregulated in human vascular smooth muscle cells during Fas-induced apoptosis, in part through a process that requires interleukin-1alpha activation. Induction of a pro-inflammatory program by apoptotic vascular smooth muscle cells may thus contribute to the pathogenesis of vascular disease.

CART peptides

CART peptides are among the newest putative peptide neurotransmitter/cotransmitters. They show no significant homology to any other peptide, and they are thought to have a role in reward and reinforcement, feeding, development, sensory processing, stress and endocrine control.

CART: from gene to function

CART was identified as a novel mRNA regulated by psychostimulant drugs. CART peptides appear to be neurotransmitters involved in a variety of functions such as feeding. The mouse gene has been characterized and localized to Chromosome 13. The processing of CART peptides is evident in Western blotting studies.

A systematic analysis of 40 random genes in cultured vascular smooth muscle subtypes reveals a heterogeneity of gene expression and identifies the tight junction gene zonula occludens 2 as a marker of epithelioid "pup" smooth muscle cells and a participant in carotid neointimal formation

An accumulation of evidence suggests that vascular smooth muscle is composed of cell subpopulations with distinct patterns of gene expression. Much of this evidence has come from serendipitous discoveries of genes marking phenotypically distinct aortic cultures derived from 12-day-old and 3-month-old rats. To identify more systematic differences, we isolated 40 genes at random from libraries of these 2 cultures and examined message expression patterns. To determine consistency of differential expression, we measured mRNA levels in 4 sets of cultures in 6 phenotypically distinct aortic cell clones and in balloon injured rat carotid arteries to determine the relevance of these differences in vitro to in vivo biology. The following 5 consistently differentially expressed genes were identified in vitro: zonula occludens 2 (ZO-2); peroxisome proliferator-activated receptor delta (PPARdelta); secreted protein, acidic and rich in cysteine (SPARC); alpha1(I)collagen; and A2, an uncharacterized gene. We examined these 5 clones during carotid artery injury and an inconsistently differentially expressed clone Krox-24 because, as an early response transcription factor, it could be involved in the injury response. PPARdelta, A2, and Krox-24 mRNAs were upregulated during the day after injury. ZO-2 and alpha1(I)collagen messages were modulated for up to a month, whereas SPARC message showed no consistent change. An analysis of ZO-2 and other tight junction genes indicates that tight junctions may play a role in smooth muscle biology. These data suggest that a systematic analysis of these libraries is likely to identify a very large number of differentially expressed genes. ZO-2 is particularly intriguing both because of this tight junction gene's pattern of prolonged over-expression after injury and because of its potential role in determining the distinctive epithelioid phenotype of smooth muscle cells identified in rat and other species.

In vitro metabolism of ceftiofur in bovine tissues

The metabolism of ceftiofur in bovine kidney, liver, muscle and lung, and the effects of the presence of cystine and glutathione in the media were evaluated using S-9 and microsomal tissue fractions. Conversion of ceftiofur to desfuroylceftiofur (DFC) was catalyzed by an esterase which was most active in kidney, followed by liver. It was not very active in muscle and lung. After DFC was liberated, it rapidly bound primarily to tissue proteins (> 56%), and was also conjugated to cysteine and glutathione. Production of DFC-cysteine by disulfide exchange of DFC with cystine and production of DFC-glutathione by conjugation of DFC to glutathione occurred in buffer if glutathione and cystine were present in the medium. These conjugations were also observed in incubations with tissue fractions, indicating that they were not inhibited by the tissues endogenous molecules. In addition, the metabolism of DFC-glutathione to DFC-cysteine was observed when tissue proteins were present. The metabolism of DFC-glutathione to DFC-cysteine was faster in kidney than in liver. Metabolites devoid of an intact beta-lactam ring were not observed in these in vitro studies.

Heterophilic NCAM-mediated cell adhesion to proteoglycans from chick embryonic brain membranes

The vertebrate neural cell adhesion molecule NCAM mediates adhesion by both homophilic and heterophilic mechanisms, with heparan sulfate proteoglycans (HSPGs) being likely heterophilic ligands. In this study, transfected chicken NCAM polypeptides expressed on mouse L cells mediated the adhesion of these cells to several different heparan sulfate proteoglycans in nonionic detergent extracts of Embryonic Day 10 chicken brain membranes. In addition, adhesion inhibition experiments suggested a hitherto-undetected role for chondroitin sulfate proteoglycans in the stimulation of NCAM-mediated adhesion to some, but not all, of the HSPG ligands. Our experiments support the view that NCAM is a multivalent adhesive molecule whose function is affected by interactions with extracellular matrix and cell surface molecules.

The large cytoplasmic domain is not required for concentration of N-CAM at cell-cell contacts in transfected mouse neuroblastoma cells

We examined the localization of the 140- and 180-kDa transmembrane isoforms of chicken N-CAM following transfection into mouse N2A neuroblastoma cells. Both isoforms were expressed at the cell surface and became partially or completely localized at areas of cell-cell contact after several days of culture or of in vitro differentiation. These results indicate that the presence of the large cytoplasmic domain of the 180-kDa N-CAM isoform is not necessary to bring about the localization of N-CAM to points of cell-cell contact.

Alpha-thrombin stimulates nuclear diglyceride levels and differential nuclear localization of protein kinase C isozymes in IIC9 cells

The mechanism by which an agonist, binding to a cell surface receptor, exerts an effect on events in the nucleus is not known. We have previously shown (Leach, K. L., Ruff, V. A., Wright, T. M., Pessin, M. S., and Raben, D. M. (1991) J. Biol. Chem. 266, 3215-3221) that alpha-thrombin treatment of IIC9 cells results in increased levels of cellular 1,2-diacylglycerol (DAG) and activation of protein kinase C (PKC). Here, we have examined whether changes in nuclear PKC and nuclear DAG also are induced following alpha-thrombin treatment. IIC9 cells were treated with 500 ng/ml alpha-thrombin, and nuclei were then isolated. Western blot analysis using isozyme-specific antibodies demonstrated the presence of PKC alpha, but not PKC epsilon or zeta in the nuclei of cells treated with either phorbol 12-myristate 13-acetate or alpha-thrombin. The increase in nuclear PKC alpha levels was accompanied by a 10-fold increase in nuclear PKC specific activity and stimulated phosphorylation of at least six nuclear proteins. The rise in nuclear PKC levels occurred rapidly and reached a maximum at 30-60 s, which was followed by a decline back to the control level over the next 15 min. In addition, alpha-thrombin treatment resulted in an immediate rise in DAG mass levels in the nuclear fractions. Kinetic analysis indicated that a maximum increase in DAG levels occurred 2.5-5 min after the addition of alpha-thrombin and remained elevated for at least 30 min. In cells labeled with [3H]myristic acid, alpha-thrombin treatment induced an increase in radiolabeled nuclear diglycerides, suggesting that the stimulated nuclear DAGs are derived, at least in part, from phosphatidylcholine. Our results suggest that increases in both nuclear DAG levels and PKC activity following alpha-thrombin treatment may play a role in mediating thrombin-induced nuclear responses such as changes in gene expression and cellular proliferation.

Tissue distribution and cellular localization of hsp56, an FK506-binding protein. Characterization using a highly specific polyclonal antibody

Heat shock protein 56 (hsp56) has been shown to be involved in two cellular pathways, as an immunophilin for FK506 and as a component of steroid receptor complexes. To help define its role in these cellular pathways, we have developed UPJ56, a polyclonal antibody raised against hsp56 purified from Jurkat cells. In Western blot experiments, hsp56 was highly expressed in rat thymus, liver, and spleen, with low levels in lung and muscle. In immunofluorescence experiments using untreated LLC-PK1 cells, fibrillar staining was seen in the cytoplasm, suggesting a cytoskeletal localization of hsp56. The nuclei were brightly stained, except for the nucleoli. Confocal microscopy demonstrated that the staining was present in all planes of the nucleus. These results suggest that hsp56 is expressed in tissues enriched in steroid receptors and is highly expressed in tissues involved in T cell function. Furthermore, the localization of hsp56 with the cytoskeleton and throughout the nucleus is consistent with its association with steroid receptor complexes.

HIV-1 protease cleaves actin during acute infection of human T-lymphocytes

Actin, one of the most abundant proteins of the cell, is hydrolyzed by the human immunodeficiency virus type 1 (HIV-1) protease during acute infection of cultured human T lymphocytes. The actin fragments produced during the course of infection are identical to those obtained by recombinant HIV-1 protease digests of (1) a lysate from uninfected T lymphocytes and (2) globular actin itself. Hydrolysis by the HIV-1 protease of physiologically important host cellular proteins during infection may have important consequences relative to viral pathogenesis.

Effects of trospectomycin on serum sensitivity of Escherichia coli UC 9451

Trospectomycin sulfate, a chemically synthesized analog of spectinomycin, exhibits a broad range of activity against both aerobes and anaerobes, including the etiological agents of sexually transmitted diseases. Its activity in vitro against Escherichia coli is considered only moderate. At subinhibitory levels, however, trospectomycin induced changes in a pathogenic strain of E. coli, UC 9451, which significantly increased its sensitivity to serum lysis. This strain of E. coli shows high-level resistance to serum in vitro, typically growing twofold within a 45-min incubation period. Following exposure to one-fifth the MIC of trospectomycin, greater than 99% of the bacteria were killed in 25% serum within 15 min. Surviving bacteria were static in this level of serum for over 3 h. Killing was due to lysis mediated by both the classical and alternative complement pathways. The bacteria exposed to trospectomycin were enlarged in both diameter and length, but they still grew at rates comparable to those of untreated bacteria. No other visible morphological changes could be directly related to the increase in serum sensitivity. The profile of outer membrane proteins obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was identical for trospectomycin-treated or untreated bacteria. However, the relative proportion of four major outer membrane proteins varied considerably.

Tumor progression- and metastasis-associated proteins identified using a model of locally recurrent rat mammary adenocarcinomas

A recently established model for local breast cancer recurrence using the 13762NF rat mammary adenocarcinoma was used to evaluate biologic and biochemical properties related to clinical outcome for this class of tumors. Sublines isolated from local tumor regrowths following surgical resection differed from each other and from the 'parental' cell lines for multiple phenotypes, including metastatic propensity. Local recurrence- and primary tumor-derived sublines were examined by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), lectin binding to electrophoretically separated proteins, and lactoperoxidase-catalyzed cell surface iodination; and differential protein patterns were compared to tumor progression and metastatic potential. 2D-PAGE revealed several quantitatively different spots which correlated with lung colonization potential. In particular, quantities of an apparently unique, non-cell-surface protein, P50.9 (Mr approximately 50,900, pI approximately 7.3) correlated inversely with metastatic propensity, suggesting that it may be associated with, among other possibilities, the negative regulation of the metastatic phenotype. P50.9 was unrelated to four similarly sized metastasis-associated proteins--tumor autocrine motility factor; the rat analog of tumor suppressor, p53; rat cytokeratin 14 or procathepsin D--as determined by amino acid analysis. A major wheat germ agglutinin binding sialoglycoprotein, gp93 (Mr approximately 93,000), was present in smaller amounts as cells were passaged in vivo and re-established as in vitro cultures [MTF7 greater than 'primary' tumor-derived lines (sc1, sc3) much greater than local recurrence-derived lines (LR1, LR1a, LR3, LR4, LR5, LR6)]. Besides cell surface glycoprotein losses, two of six local recurrence-derived sublines expressed a wheat germ agglutinin-binding sialoglycoprotein, gp110 (Mr approximately 110,000), previously undetected on any of the other cell lines including the parental populations. gp110 was found in LR3 and LR6 which were relatively highly metastatic; however, correlation with metastatic potential failed because gp110 was not present on the metastatic parental cell line, MTF7. These results demonstrate specific quantitative and qualitative protein differences associated with the selection of locally recurrent mammary tumors.

Rapid modulation of a 64 K dalton fibroblast protein: a PDGF mediated early cellular event

The results presented here reveal a novel platelet derived growth factor (PDGF) mediated early cellular event. Treatment of growth arrested Balb/c3T3 fibroblasts with PDGF induces a specific and rapid modulation of a 64,000 Dalton (64 KD) protein preexisting in quiescent cells. The kinetics of 64 KD protein modulation indicate that, temporally, this PDGF mediated step lies between the membrane associated immediate events such as receptor autophosphorylation or ion mobilization and the earliest known transcriptional event, the activation of the proto-oncogene c-fos.

Dietary management of canine and feline chronic renal failure

Nutritional therapy is the mainstay of management of chronic renal failure in dogs and cats. Diets designed for use in renal failure are typically reduced in protein, phosphorus, and sodium content. These and other dietary modifications are designed to prevent or ameliorate clinical signs of uremia, minimize disturbances associated with excesses or losses of electrolytes and minerals, arrest or retard progression of renal failure, and maintain adequate nutrition.

Mode of fibroblast growth enhancement by human interleukin-1

Previous studies have demonstrated that interleukin-1 (IL-1) stimulates fibroblast growth (Schmidt, J. A., S. B. Mizel, D. Cohn, and I. Green. 1982. J. Immunol. 128:2177-2182) and binds to specific, high affinity receptors of BALB/c3T3 cells (Bird, T. A., and J. Saklatval. 1986. Nature (Lond.). 324:263-265, 266-268). We have investigated the mechanism of fibroblast growth stimulation by IL-1. Addition of fibroblast growth factor derived from platelets (PDGF) to a quiescent culture of BALB/c3T3 cells produced 8-10-fold increase in DNA synthesis during 24-h incubation. The cellular action of PDGF was mediated through competence induction and required synergistic action of plasma-derived factors for full mitogenic activity. When tested at a wide range of concentrations (0.1-100 pM), natural IL-1 or recombinant IL-1 produced only a maximum of 5-10% of DNA synthesis elicited in response to PDGF or serum. Induction of DNA synthesis required continuous presence of IL-1 and did not exhibit synergism with plasma. Competence induction and mitogenic stimulation by PDGF was associated with early induction of proteins P32, P38, P46-48, P75, and changes in cytoskeletal organization. Examination of these early cellular changes showed that IL-1 did not produce similar induction of cellular proteins and the morphological changes associated with growth stimulation. These results suggest that the mode of IL-1 action on BALB/c3T3 was not through competence induction. When IL-1 was added to cells rendered competent by brief exposure to PDGF, 10-15% additional DNA synthesis occurred during the first 24 h. Extended incubation of PDGF-treated cells in the presence of IL-1 revealed that the stimulation by IL-1 occurred predominantly during the subsequent cycle of DNA replication, wherein DNA synthesis reached three- to fivefold higher than the untreated cultures. We conclude (a) IL-1 alone is not a potent mitogen for BALB/c3T3 cells, and does not bring cells out of the growth arrest Go phase, (b) treatment with PDGF renders the cells more responsive to IL-1, (c) part of the IL-1 action on competent cells may be characterized as progression inducing activity, further, (d) our results indicate that action of IL-1 on PDGF-treated cells produces sustained DNA synthesis for an extended period, perhaps by preventing the entry of cells into growth arrest Go phase.

A nonurea electrophoretic gel system for resolution of polypeptides of Mr 2000 to Mr 200,000

A sodium dodecyl sulfate-polyacrylamide gel electrophoresis system which resolves proteins and peptides from Mr 2000 to Mr 200,000 is described. Gradients of polyacrylamide, crosslinker, and glycerol buffered in Tris-phosphate (pH 6.8) are employed. Neither urea nor a stacking gel is required. This system has been used to separate molecules below Mr 3000 which differed by only seven amino acid residues, yet has the capacity to survey masses up to Mr 200,000 on the same gel. Examples are given for separations of myoglobin cyanogen bromide fragments and adrenocorticotropin peptides. Utilizing the same gradient slab gel system in tandem with isoelectric focusing, a two-dimensional separation pattern of mammalian liver cell lysate is shown. A comparison of two different silver stain methods with this system is also given.

The antigenic relatedness of proteins from human and simian prostate fluid

Two-dimensional electrophoretic analysis of human prostate fluid reveals an abundant protein migrating to a molecular weight of 15 kD and an isoelectric point of 5.5. Polyclonal antibodies were raised specifically to microgram quantities of electrophoresed, excised, and eluted PSP15 (prostate secretory protein). Western immunoblot analysis using these antibodies showed they not only react to PSP15, but cross-react with simian prostate and human seminal fluid proteins of similar molecular weights. Two-dimensional gel immunoblots strongly suggest that the seminal protein and PSP15 are the same, thereby providing a more accessible source of the protein. The antibody to the human PSP15 cross-reacted with neither prostate fluid from the ventral lobe of the rat prostate nor the prostate fluid from the beagle dog.

Insulin-induced rapid decrease of a major protein in fat cell plasma membranes

In order to increase our understanding of the mode of action of insulin in rat fat cells, we investigated the effect of insulin on protein concentrations in purified fat cell fractions using two-dimensional electrophoresis in combination with an ultrasensitive color silver stain technique. Incubation of fat cells with insulin caused a 90% decrease in the plasma membrane concentration of a major plasma membrane protein with a molecular mass of 90 kDa. The insulin effect was dose-dependent with a half-maximal effect at 9.5 microunits/ml, and time-dependent with a t 1/2 of less than 20 s. Insulin-like growth factor I, orthovanadate, and lanthanum mimicked the effect of insulin. Likewise, fractionation of adipocytes in the presence of divalent cation chelating agents caused a similar reduction in the concentration of the 90 kDa protein, and it was possible to overcome the effects of the chelating agents by adding equivalent amounts of calcium. This suggests the involvement of calcium. The 90 kDa protein was also found in low and high density microsomes, but it was not affected in those fractions by either insulin or chelators. It is suggested from the study that the movement of a 90 kDa protein in fat cell plasma membranes probably represents part of the transmission system in the mechanism of insulin action in rat adipocytes.

Alloxan-induced hyperglycemia in rats is reduced by 16,16-dimethyl-PGE2

Female rats were treated with subcutaneous 16,16-dimethyl-PGE2 (1-75 micrograms/kg) for 24, 18, and 0.5 h prior to and 6, 24, and 48 h after intravenous beta cell destruction. Protection was assessed by morphological examination of beta cells and the level of fasting hyperglycemia seen 72 h after alloxan treatment. Prostaglandin reduced the degree of alloxan-induced hyperglycemia in a dose-dependent fashion but had no demonstrable effect on morphological assessment of beta cell destruction. However, prostaglandin treatment by itself induced transient (0-2 h) hyperglycemia that could be correlated inversely with the level of fasting blood glucose observed 72 h after alloxan treatment. Administration of oral glucose, which mimics the prostaglandin-induced hyperglycemia, afforded protection against alloxan challenge comparable to that produced by the prostaglandin. Thus, it appears that reduction of alloxan-induced hyperglycemia by 16,16-dimethyl-PGE2 may be linked to the transient hyperglycemia produced prior to alloxan administration.

Measuring various drug use dimensions with a calendar method

This note presents a technique used to acquire a variety of time-specific data on drug use. The calendar technique involves self-reported patterns of consumption and any changes therein, including cessation. Advantages of this technique over other approaches are discussed, and examples of the variety of use measures that can be derived from the calendar method are illustrated.