Ribozyme-mediated inhibition of rat leukocyte-type 12-lipoxygenase prevents intimal hyperplasia in balloon-injured rat carotid arteries

BACKGROUND

12-Lipoxygenase (12-LO) products of arachidonate metabolism have growth and chemotactic effects in vascular smooth muscle cells. We have also recently demonstrated increased 12-LO mRNA and protein expression in the neointima of balloon-injured rat carotid arteries. In this study, we evaluated whether 12-LO activation plays a role in neointimal thickening in this rat model by using a specific ribozyme (Rz) directed to rat 12-LO.

METHODS AND RESULTS

We designed a chimeric DNA-RNA hammerhead Rz to cleave rat leukocyte-type 12-LO mRNA. This Rz dose-dependently cleaved a 166-nucleotide target 12-LO mRNA substrate in vitro and reduced 12-LO mRNA and protein expression in rat vascular smooth muscle cells. A control mutant Rz (MRz) with a point mutation in the catalytic site was inactive. To test the in vivo efficacy of the 12-LO Rz, the left common carotid arteries of rats were injured with a balloon catheter. The distal half of the injured arteries was treated with Rz or MRz mixed with lipofectin. The proximal half received only lipofectin. Twelve days after injury, intima-to-media ratios were significantly lower in the Rz-treated sections than in untreated sections from the same rat (0.742+/-0.16 versus 1.749+/-0.12, P:<0.001). In contrast, the MRz had no significant effect.

CONCLUSIONS

These results indicate the important role of the leukocyte-type 12-LO pathway in restenosis in response to injury.

Evidence that increased 12-lipoxygenase activity induces apoptosis in fibroblasts

The 12-lipoxygenase (LO) enzyme has been implicated in playing a role in pancreatic beta cell inflammatory damage and atherosclerosis. 12-LO reacts with fatty acids to form hydroperoxides which may alter cellular growth. In this study we investigated the direct effect of mouse leukocyte type 12-LO cDNA overexpression on apoptosis in Chinese hamster ovary fibroblast cells that also stably overexpress the angiotensin II type 1a receptor. CHO-AT1a cells expressing background levels of 12-LO exhibited clear increases in growth in response to angiotensin II. In contrast, the new 12-LO transfected cells (CHO-AT1a/ML12-LO cells) displayed reduced basal and angiotensin Il-induced growth compared to CHO-AT1a cells. Furthermore, serum-deprivation resulted in a significantly greater number of non-viable cells in clones having the greatest magnitude of 12-LO overexpression. These results suggested that reduction of the proliferation rate of CHO-AT1a/ML12-LO cells was due to an increasing rate of cell death. To determine whether the increase in cell death was due to apoptosis, we evaluated nuclear DNA fragmentation, cell morphologic changes, and activation of caspase-3. Cells overexpressing 12-LO cDNA displayed all these changes characteristic of apoptosis. In addition the 12-LO product, 12-hydroperoxyeicosatetraenoic acid (12-HPETE), directly induced apoptosis in CHO-AT1a cells. These results demonstrate for the first time that 12-LO activation can lead to apoptosis in fibroblasts, suggesting a role of 12-LO in leading to inflammatory mediated cellular damage.

Seasonal incidence of Aedes (Rhinoskusea) portonovoensis in a mangrove forest of South India

The seasonal incidence of Aedes (Rhinoskusea) portonovoensis in its type locality is reported. This is the Ist information on the bionomics of this species described from a mangrove forest in South India. Peak density of adults occurred in August. The larval habitat of the species is also defined.

Angiotensin II increases neuronal delayed rectifier K(+) current: role of 12-lipoxygenase metabolites of arachidonic acid

Angiotensin II (Ang II) elicits an Ang II type 2 (AT(2)) receptor-mediated increase in voltage-dependent delayed rectifier K(+) current (I(KV)) in neurons cultured from newborn rat hypothalamus and brain stem. In previous studies, we have determined that this effect of Ang II is mediated via a Gi protein, activation of phospholipase A(2) (PLA(2)), and generation of arachidonic acid (AA). AA is rapidly metabolized within cells via lipoxygenases (LO), cyclooxygenase (COX) or p450 monooxygenase enzymes, and the metabolic products are known regulators of K(+) currents and channels. Thus in the present study, we have investigated whether the AT(2) receptor-mediated effects of Ang II on neuronal I(KV) require AA metabolism and if so, which metabolic pathways are involved. The data presented here indicate that the stimulatory actions of Ang II and AA on neuronal I(KV) are attenuated by selective blockade of 12-LO enzymes. However, the effects of Ang II are not altered by blockade of 5-LO or p450 monooxygenase enzymes. Furthermore, the actions of Ang II are mimicked by a 12-LO metabolite of AA, but 5-LO metabolites such as leukotriene B(4) and C(4) do not alter neuronal I(KV). These data indicate that the AT(2) receptor-mediated stimulation of neuronal I(KV) is partially mediated through 12-LO metabolites of AA.

Evidence that pioglitazone, metformin and pentoxifylline are inhibitors of glycation

Enhanced formation and accumulation of advanced glycation end products (AGEs) have been proposed to play a major role in the pathogenesis of diabetic complications, and atherosclerosis, leading to the development of a range of diabetic complications including nephropathy, retinopathy and neuropathy. Several potential drug candidates as AGE inhibitors have been reported recently. Aminoguanidine is the first drug extensively studied. However, there are no currently available medications known to block AGE formation. We have previously reported a number of novel and structurally diverse compounds as potent inhibitors of glycation and AGE formation. We have now studied several of the existing drugs, which are in therapeutic practice for lowering blood sugar or the treatment of peripheral vascular disease in diabetic patients, for possible inhibitory effects on glycation. We show that that three compounds; pioglitazone, metformin and pentoxifylline are also inhibitors of glycation.

Genes identified by an expression screen of the vector mosquito Anopheles gambiae display differential molecular immune response to malaria parasites and bacteria

We performed a gene expression screen of the entire transcriptome of the major African malaria vector Anopheles gambiae for immune response genes in adult female mosquitoes, which is the developmental stage infected by malaria parasites. Mosquitoes were immune-stimulated for subtractive cloning by treatment with bacterial lipopolysaccharide, a potent and general elicitor of the innate immune response, and by injury. The screen yielded a highly enriched cDNA library in which more than half of the clones were immune responsive. In this paper, we describe 23 immune-regulated genes, including putative protease inhibitors, serine proteases, regulatory molecules, and a number of genes without known relatives. A molecule related to the protease inhibitor alpha-2-macroglobulin responded strongly to malaria parasite infection, but displayed little or no response to bacteria, whereas other genes exhibited the inverse pattern. These results indicate that the insect immune system discriminates between molecular signals specific to infection with bacteria and malaria parasites.

Modelling covariance structure in the analysis of repeated measures data

The term 'repeated measures' refers to data with multiple observations on the same sampling unit. In most cases, the multiple observations are taken over time, but they could be over space. It is usually plausible to assume that observations on the same unit are correlated. Hence, statistical analysis of repeated measures data must address the issue of covariation between measures on the same unit. Until recently, analysis techniques available in computer software only offered the user limited and inadequate choices. One choice was to ignore covariance structure and make invalid assumptions. Another was to avoid the covariance structure issue by analysing transformed data or making adjustments to otherwise inadequate analyses. Ignoring covariance structure may result in erroneous inference, and avoiding it may result in inefficient inference. Recently available mixed model methodology permits the covariance structure to be incorporated into the statistical model. The MIXED procedure of the SAS((R)) System provides a rich selection of covariance structures through the RANDOM and REPEATED statements. Modelling the covariance structure is a major hurdle in the use of PROC MIXED. However, once the covariance structure is modelled, inference about fixed effects proceeds essentially as when using PROC GLM. An example from the pharmaceutical industry is used to illustrate how to choose a covariance structure. The example also illustrates the effects of choice of covariance structure on tests and estimates of fixed effects. In many situations, estimates of linear combinations are invariant with respect to covariance structure, yet standard errors of the estimates may still depend on the covariance structure.

Molecular mechanisms of tumor necrosis factor alpha gene expression in monocytic cells via hyperglycemia-induced oxidant stress-dependent and -independent pathways

Increased oxidative stress has been reported in vivo in the diabetic state via the production of reactive oxygen species (ROS). Such stress is bound to play a key role on activation of circulating monocytes, leading to the accelerated atherosclerosis observed in diabetics. However the exact molecular mechanisms of monocyte activation by high glucose is currently unclear. Here, we demonstrate that chronic high glucose (CHG) causes a dramatic increase in the release of the inflammatory cytokine tumor necrosis factor alpha (TNFalpha), at least in part through enhanced TNFalpha mRNA transcription, mediated by ROS via activation of transcription factors nuclear factor kappaB (NF-kappaB) and activating protein-1 (AP-1). TNFalpha accumulation in the conditioned media was increased 10-fold and mRNA levels were increased 11.5-fold by CHG. The following observations supported that both NF-kappaB and AP-1 mediated enhanced TNFalpha transcription by CHG: 1) A 295-base pair fragment of the proximal TNFalpha promoter containing NF-kappaB and AP-1 sites reproduced the effects of CHG on TNFalpha transcription in a luciferase reporter assay, 2) mutational analyses of both NF-kappaB and the AP-1 sites abrogated 90% of the luciferase activity, 3) gel-shift analysis using the binding sites showed activation of NF-kappaB and AP-1 in CHG nuclear extracts, and 4) Western blot analyses demonstrated elevated nuclear levels of p65 and p50 and decreased cytosolic levels of IkappaBalpha in CHG-treated monocytes. That ROS acted as a key intermediate in the CHG pathway was supported by the following evidence: 1) increased superoxide levels similar to those observed with PMA or TNFalpha, 2) increased phosphorylation of stress-responsive mitogen-activated protein kinases p38 and JNK-1, 3) counteraction of the effects of CHG on TNFalpha production, the 295TNFluc reporter activity, activation of NF-kappaB, and repression of IkappaBalpha by antioxidants and p38 mitogen-activated protein kinase inhibitors. The study suggests that ROS function as key components in the regulatory pathway progressing from elevated glucose to monocyte activation.

Alcohol use patterns predict high-risk HIV behaviors among active injection drug users

The purpose of this study was to determine if alcohol use is independently associated with needle-sharing behavior. Participants were 196 active injection drug users recruited into the Providence, Rhode Island Needle Exchange program between July 1997 and March 1998. All subjects were administered a 45-minute questionnaire that included questions on quantity/frequency of alcohol use and the alcohol abuse section of the Structured Clinical Interview for DSM-III-R (SCID; Spitzer, Williams, Gibbon, & First, 1992). Drug risk behaviors, including needle sharing were assessed using the HIV Risk Assessment Battery (RAB; Navaline et al., 1994). Of 196 IDUs, 60% had used alcohol in the last month. Twenty-eight percent met criteria from the Diagnostic and Statistical Manual for Mental Disorders, 3rd ed., rev. (DSM-III-R; American Psychiatric Association, 1987) for alcohol abuse over the last 6 months. One half of IDUs had shared needles in the last 6 months. Increasing levels of alcohol ingestion were associated with greater RAB drug risk scores and greater needle sharing. Using multiple logistic regression, high-level "at-risk" alcohol use (odds ratio [OR], 2.5) and alcohol abuse (OR, 2.3) were significantly associated with needle sharing when controlling for other demographic and behavioral factors previously found to be associated with sharing. The results of this study showed that prevalence of alcohol abuse is high in this population and is associated with needle sharing. HIV prevention effects in needle exchange programs should address alcohol use.

Regulation of the rat neutral cytosolic cholesteryl ester hydrolase promoter by hormones and sterols: a role for nuclear factor-Y in the sterol-mediated response

Expression of the rat liver neutral cytosolic cholesteryl ester hydrolase (CEH) gene is regulated by glucocorticoids, thyroxine, and agents that perturb cholesterol metabolism. The present studies identify the putative hormone response elements in the CEH promoter. They also define the roles of two previously identified sterol regulatory elements (SRE-92 and SRE-160) and a putative nuclear factor-Y (NF-Y) binding site with a consensus ATTGG (inverted CCAAT) motif (Natarajan, R., S. Ghosh, and W. M. Grogan. 1998. Biochem. Biophys. Res. Commun. 243: 349;-355). CEH promoter-reporter gene constructs were transiently transfected into HepG2 cells to evaluate promoter activity. Results indicated that the CEH gene has two complex glucocorticoid response units in distal portions of the promoter corresponding to consensus glucocorticoid regulatory sequences as well as putative thyroid hormone response elements. CEH promoter-reporter constructs with the proximal 189 bp of the wild-type or mutated sequences were also transfected into HepG2 cells. Activity of the wild-type construct increased when incubated in sterol depleted media or when co-expressed with a mature sterol regulatory element binding protein (SREBP-2). These responses were suppressed by mutations in SRE-92, SRE-160, or NF-Y, indicating that these cis elements are sufficient for sterol-mediated regulation of the CEH promoter. Gel mobility shift assays further demonstrated that NF-Y binds to the inverted CCAAT box motif and is required for the sterol-mediated regulation. These results indicate that multiple cis-elements regulate transcription of the cholesteryl ester hydrolase (CEH) gene, consistent with the reported regulation of CEH expression.-Natarajan, R., S. Ghosh, and W. M. Grogan. Regulation of the rat neutral cytosolic cholesteryl ester hydrolase promoter by hormones and sterols: a role for nuclear factor-Y in the sterol-mediated response.

Lipoxygenase products increase monocyte adhesion to human aortic endothelial cells

The development of atherosclerosis is accelerated in individuals with type 2 diabetes. Adhesion of monocytes to the vascular endothelium is a key initial step in atherogenesis. We have previously shown that monocyte adhesion to human aortic endothelial cells (HAECs) cultured long-term in high-glucose medium (25 mmol/L, 2 passages) is increased compared with cells grown in normal glucose (5 mmol/L). One potential mechanism for increased monocyte adhesion to HAECs under hyperglycemic conditions is via the 12-lipoxygenase (12-LO) pathway. In this study, we demonstrated in HAECs that the major LO metabolite of arachidonic acid was the 12-LO product, 12(S)-hydroxyeicosatetraenoic acid [12(S)-HETE], which was increased severalfold in HAECs cultured under high-glucose conditions. Furthermore, treatment of HAECs with 12(S)-HETE induced monocyte, but not neutrophil, adhesion an average of 3-fold (range of 1.5- to 5-fold) compared with untreated cells (75+/-5 versus 26+/-1 monocytes per field, respectively, P<0.001). Expression of the adhesion molecules vascular cell adhesion molecule-1, E-selectin, and intercellular adhesion molecule-1 was not significantly increased. However, both glucose and 12(S)-HETE induced a 60% increase in HAEC surface expression of connecting segment-1 (ie, CS-1) fibronectin, a ligand for very late-acting antigen-4 (VLA-4). The antibodies used to block monocyte integrin VLA-4 and leukocyte function-related antigen-1, a monocytic counterreceptor for intercellular adhesion molecule-1, inhibited the ability of both 12-LO products and high glucose to induce monocyte adhesion. These results definitively demonstrate for the first time in HAECs that the 12-LO pathway can induce monocyte-endothelial cell interaction and that the effects of glucose may be mediated, at least in part, through this pathway. Thus, these results suggest that the 12-LO pathway may play a role in the increased susceptibility of diabetics to atherosclerosis.

Effect of smoking on tibial shaft fracture healing

Of 146 consecutive closed and Grade I open tibia shaft fractures treated with cast immobilization, external fixation, or intramedullary rod fixation during a 4-year period, 44 of 76 (58%) tibias of patients who smoked and 59 of 70 (84%) tibias of patients who did not smoke had followup to union or followup beyond 1 year. The demographics, fracture patterns, and treatments of the two groups were similar. Two of the 44 patients who smoked had nonunions at the 1-year followup, whereas none of the patients who did not smoke had nonunions. Of the 103 tibias with complete followup to union, the median time to clinical healing for patients who smoked (269 days) was significantly greater than that of patients who did not smoke (136 days). Likewise, there was a 69% delay in radiographic union in the group that smoked as interpreted by a radiologist blinded to the two groups. Statistical differences in clinical and radiographic healing rates between those who smoked and those who did not smoke were observed for patients receiving intramedullary fixation or external fixation. Statistical differences were not seen in the clinical and radiographic healing of tibias treated with cast immobilization, although tibias of patients who smoked took 62% longer to heal. The current data suggest that tibias of patients who smoke who require treatment with intramedullary nailing or external fixation require more time to heal than do those of patients who do not smoke.

Modeling heterogeneity in nest survival data

Current statistical methods for estimating nest survival rates assume that nests are identical in their propensity to succeed. However, there are several biological reasons to question this assumption. For example, experience of the nest builder, number of nest helpers, genetic fitness of individuals, and site effects may contribute to an inherent disparity between nests with respect to their daily mortality rates. Ignoring such heterogeneity can lead to incorrect survival estimates. Our results show that constant survival models can seriously underestimate overall survival in the presence of heterogeneity. This paper presents a flexible random-effects approach to model heterogeneous nest survival data. We illustrate our methods through data on redwing blackbirds.

Hyperglycemia-induced activation of nuclear transcription factor kappaB in vascular smooth muscle cells

The transcriptional nuclear factor (NF)-kappaB can be activated by diverse stimuli such as cytokines, mitogens, oxidative stress, and lipids, leading to the transactivation of several genes that play important roles in the development of atherosclerosis. Because oxidative stress may play a key role in the pathogenesis of diabetic vascular disease, we have examined whether culture of porcine vascular smooth muscle cells (PVSMCs) under high glucose (HG) conditions (25 mmol/l) to simulate the diabetic state can lead to the activation of NF-kappaB, and also whether cytokine- or growth factor-induced NF-kappaB activation is altered by HG culture. We observed that PVSMCs cultured in HG showed significantly greater activation of NF-kappaB in the basal state compared with cells cultured in normal glucose (NG) (5.5 mmol/l). Treatment of the cells with cytokines, such as tumor necrosis factor (TNF)-alpha and interleukin-1beta, or with growth factors, such as platelet-derived growth factor, insulin-like growth factor-I, and epidermal growth factor, all led to NF-kappaB activation in cells cultured in both NG and HG. However, their effects were markedly greater in HG. The augmented TNF-alpha-induced NF-kappaB activation in HG was associated with increased TNF-alpha-mediated transcriptional activation of the vascular cell adhesion molecule-1 promoter. Immunoblotting with an antibody to the p65 subunit of NF-kappaB indicated that the levels of this protein were higher in the nuclear extracts from cells cultured in HG compared with NG. Cells cultured in HG also produced significantly greater amounts of the reactive oxygen species superoxide. HG-induced NF-kappaB activation was inhibited by a protein kinase C inhibitor, calphostin C. These results suggest that hyperglycemia-induced activation of NF-kappaB in VSMCs may be a key mechanism for the accelerated vascular disease observed in diabetes.

Colostomy closure: impact of preoperative risk factors on morbidity

The objective of this study was to stratify patients for colostomy closure into risk categories according to preoperative variables. This was a retrospective case series. Median follow-up was 82 months. A tertiary care academic medical center was the setting for this study. A study sample of 155 consecutive patients who underwent colostomy closure at a single institution between 1985 and 1995 were included in this study. The following preoperative variables were analyzed: indication for colostomy fashioning; age; gender; American Society of Anesthesiology (ASA) class; presence of cardiac, renal, or pulmonary dysfunctions; presence of diabetes mellitus; and immunosuppression. The occurrence of adverse outcome, as evidenced by postoperative morbidity and mortality, was used as the main outcome measure. Complications occurred in 49 patients (31.6%), including a 1.3 per cent mortality. There was a trend of increasing morbidity with increasing ASA class. The single factor that showed a statistically significant increase in morbidity was the presence of diabetes (P = 0.036). Predicted probabilities of complications for patients with ASA III with renal disease was 31 per cent, increased to 47.9 per cent if cardiac disease was also present and to 77 per cent with the addition of diabetes. The presence of diabetes carries an independent risk factor for adverse outcome in colostomy closure. This study provides information about stratification of postoperative risk based on commonly available preoperative variables. In the majority of cases, colostomy closure seems to carry a very acceptable complication rate. In selected patients with multiple preoperative risk factors, the morbidity becomes significantly higher.

Induction of monocyte binding to endothelial cells by MM-LDL: role of lipoxygenase metabolites

Treatment of human aortic endothelial cells (EC) with minimally oxidized LDL (or minimally modified LDL, MM-LDL) produces a specific pattern of endothelial cell activation distinct from that produced by LPS, tumor necrosis factor-alpha, and interleukin-1, but similar to other agents that elevate cAMP. The current studies focus on the signal transduction pathways by which MM-LDL activates EC to bind monocytes. We now demonstrate that, in addition to an elevation of cAMP, lipoxygenase products are necessary for the MM-LDL response. Treatment of EC with inhibitors of the lipoxygenase pathway, 5,8,11, 14-eicosatetraynoic acid (ETYA) or cinnamyl-3, 4-dihydroxy-alpha-cyanocinnamate (CDC), blocked monocyte binding in MM-LDL-treated EC (MM-LDL=118+/-13%; MM-LDL+ETYA=33+/-4%; MM-LDL+CDC=23+/-4% increase in monocyte binding) without reducing cAMP levels. To further investigate the role of the lipoxygenase pathway, cellular phospholipids were labeled with arachidonic acid. Treatment of cells for 4 hours with 50 to 100 microg/mL MM-LDL, but not native LDL, caused a 60% increase in arachidonate release into the medium and increased the intracellular formation of 12(S)-HETE (approximately 100% increase). There was little 15(S)-HETE present, and no increase in its levels was observed. We demonstrated that 12(S)-HETE reversed the inhibitory effect of CDC. We also observed a 70% increase in the formation of 11,12-epoxyeicosatrienoic acid (11, 12-EET) in cells treated with MM-LDL. To determine the mechanism of arachidonate release induced by MM-LDL, we examined the effects of MM-LDL on intracellular calcium levels. Treatment of EC with both native LDL and MM-LDL caused a rapid release of intracellular calcium from internal stores. However, several pieces of evidence suggest that calcium release alone does not explain the increased arachidonate release in MM-LDL-treated cells. The present studies suggest that products of 12-lipoxygenase play an important role in MM-LDL action on the induction of monocyte binding to EC.

Evidence for 12-lipoxygenase induction in the vessel wall following balloon injury

OBJECTIVE

Vascular smooth muscle cell (VSMC) migration and proliferation are key events in the development of atherosclerosis and restenosis following angioplasty. These events are mediated by several growth factors and cytokines whose cellular effects include activation of phospholipases and arachidonic acid metabolism via the lipoxygenase (LO) pathway. Since 12-LO products have potent growth and chemotactic effects, we have examined if 12-LO is upregulated in the neointima of injured rat carotid arteries and also if LO inhibition could attenuate neointimal thickening.

METHODS

The left common carotid arteries of male Sprague Dawley rats were injured using a 1.8 F PTCA balloon catheter. Four-fourteen days after injury, injured and uninjured tissue samples were processed for histology, and immunohistochemistry or polymerase chain reaction (PCR) to examine 12-LO expression.

RESULTS

Twelve days after injury, immunohistochemical staining with a 12-LO antibody revealed intense staining in injured left carotid arteries, mainly in neointimal VSMCs and inflammatory cells, but not in the uninjured right arteries. There was also a marked upregulation of 12-LO mRNA (over five-fold by competitive PCR) in the injured arteries. Treatment of the arteries with a LO inhibitor, phenidone, soon after injury resulted in significant inhibition of neointimal thickening. In contrast, a cyclooxygenase inhibitor, ibuprofen, had no effect.

CONCLUSIONS

These results indicate for the first time that balloon injury results in marked induction of 12-LO mRNA and protein expression in the vessel wall. Furthermore, LO pathway activation may mediate, at least in part, the development of the lesion or plaque instability, suggesting a novel target for therapeutic intervention to block these pathological events.

Angiotensin II signaling in vascular smooth muscle cells under high glucose conditions

The mechanisms responsible for the accelerated cardiovascular disease in diabetes, as well as the increased hypertrophic effects of angiotensin II (Ang II) under hyperglycemic conditions, are not very clear. We examined whether the culture of vascular smooth muscle cells (VSMC) under hyperglycemic conditions to simulate the diabetic state can lead to increased activation of key growth- and stress-related kinases, such as the mitogen-activated protein kinases (MAPKs), in the basal state and in response to Ang II. Treatment of porcine VSMC for short time periods (0.5 to 3 hours) with high glucose (HG; 25 mmol/L) markedly increased the activation of the extracellular signal-regulated kinase (ERK1/2) and c-Jun/N-terminal kinase (JNK) relative to cells cultured in normal glucose (NG; 5.5 mmol/L). p38 MAPK also was activated by HG, and this effect remained sustained for several hours. Ang II treatment increased the activity of all 3 families of MAPKs. Ang II-induced ERK activation was potentiated nearly 2-fold in cells treated with HG for 0.5 hour. However, Ang II-induced JNK was not altered. In VSMC cultured for 24 hours with HG, Ang II and HG displayed an additive response on p38 MAPK activity. MAPKs can lead to activation of transcription factors such as activator protein-1 (AP-1). HG alone significantly increased AP-1 DNA-binding activity. Furthermore, Ang II and HG combined had additive effects on AP-1 activity. These results suggest that increased activation of specific MAPKs and downstream transcription factors, such as AP-1, may be key mechanisms for the increased VSMC growth potential of HG alone and of Ang II under HG conditions.

Insulin potentiates platelet-derived growth factor action in vascular smooth muscle cells

Correlative studies have indicated that hyperinsulinemia is present in many individuals with atherosclerosis. Insulin resistance has also been linked to cardiovascular disease. It has proved to be difficult to decipher whether hyperinsulinemia or insulin resistance plays the most important role in the pathogenesis of atherosclerosis and coronary artery disease. In this study, we demonstrate that insulin increases the amount of farnesylated p21Ras in vascular smooth muscle cells (VSMC), thereby augmenting the pool of cellular Ras available for activation by platelet-derived growth factor (PDGF). In VSMC incubated with insulin for 24 h, PDGF's influence on GTP-loading of Ras was significantly increased. Furthermore, in cells preincubated with insulin, PDGF increased thymidine incorporation by 96% as compared with a 44% increase in control cells (a 2-fold increment). Similarly, preincubation of VSMC with insulin increased the ability of PDGF to stimulate gene expression of vascular endothelial growth factor 5- to 8-fold. The potentiating influence of insulin on PDGF action was abrogated in the presence of a farnesyltransferase inhibitor. Thus, the detrimental influence of hyperinsulinemia on the arterial wall may be related to the ability of insulin to augment farnesyltransferase activity and provide greater amounts of farnesylated p21Ras for stimulation by various growth promoting agents.

Occurrence of Culex (Culiciomyia) Spathifurca (Edwards) (Diptera: Culicidae) in India--new country record

Culex (Culiciomyia) spathifurca (Edwards) is recorded for the 1st time in India. Immature specimens of this species were collected from tree holes in a mangrove forest. Notes on the larval habitat are given.

Role of lipoxygenases in breast cancer

The interaction of growth factors such as epidermal growth factor (EGF) with their receptors on breast cancer cells can lead to the hydrolysis of phospholipids and release of fatty acids such as arachidonic acid which can be further metabolized by the lipoxygenase (LO) pathway. Several LO products have been shown to stimulate oncogenes and have mitogenic and chemotactic effects. The 12-LO product, 12-hydroxyeicosatetraenoic acid (12(S)HETE), has been shown to play a key role in mediating several steps of the process of hematogenous metastasis and tumor cell adhesion. 12-LO can also be activated by several growth factors and inflammatory cytokines. A growing body of evidence suggests that specific metabolites of arachidonic and/or linoleic acid serve as central elements in signal pathways necessary for cell mitogenesis as induced by growth factors or oncogenic transformation. This review examines the role of LOs in breast cancer. The growth of breast cancer cells has been shown to increased by certain LO products and, LO pathway inhibitors could block the growth of some breast cancer cells. 12-LO activity and expression was increased in breast cancer tissues relative to the uninvolved normal tissue, and also in cultured breast cancer cells relative to normal breast cells. Treatment of the breast cancer cell line, MCF-7 cells, with epidermal growth factor (EGF), led to significant increases in 12-LO activity and expression. Thus, activation of the 12-LO pathway may play a key role in basal and EGF-induced breast cancer cell growth.

Pilot trial of albuterol in facioscapulohumeral muscular dystrophy. FSH-DY Group

BACKGROUND/OBJECTIVE

Facioscapulohumeral muscular dystrophy (FSHD) is currently untreatable, and there have been few therapeutic trials of any agent in the disease. Animal studies have demonstrated that beta2-adrenergic agonists induce muscle hypertrophy and prevent atrophy after a variety of physical and biochemical insults, and two human studies have shown that these agents increase certain measures of strength in healthy volunteers. We conducted an open-label pilot trial of a beta2-agonist (albuterol) in patients with FSHD.

METHODS

Fifteen FSHD patients were given sustained-release albuterol (16.0 mg/day) for 3 months. The primary outcome measure was lean body mass, which was assessed through dual energy X-ray absorptiometry (DEXA). Strength was evaluated through maximal voluntary isometric contraction testing (MVICT) and manual muscle testing.

RESULTS

Albuterol significantly increased DEXA lean body mass (the skeletal muscle compartment) by 1.29 +/- 1.18 kg (mean +/- SD, p = 0.001). Strength assessed through composite MVICT scores also increased by an average of 0.33 +/- 0.60 (p = 0.05), representing an overall 12% improvement in strength.

CONCLUSIONS

These encouraging results suggest that beta2-agonists may have a role in treating FSHD and possibly other neuromuscular diseases. The effects of albuterol in FSHD are currently being evaluated in a larger, randomized, double-blind, placebo-controlled trial lasting 1 year.

Regulation of hepatic neutral cholesteryl ester hydrolase by hormones and changes in cholesterol flux

To understand molecular events in regulation of hepatic neutral cholesteryl ester hydrolase (EC3.1.1.13; CEH), catalytic activity, protein mass, and mRNA levels were measured in rats with various perturbations of hepatic cholesterol metabolism. Cholesterol feeding decreased activity (56 +/- 2%), mass (44 +/- 2%), and mRNA (14 +/- 3%). The cholesterol precursor mevalonate also decreased activity (42 +/- 6%), mass (76 +/- 3%), and mRNA (23 +/- 16%). Inhibition of cholesterol biosynthesis by lovastatin increased activity (65 +/- 12%) and mRNA (31 +/- 24%). Stimulation of cholesterol efflux by chronic biliary diversion increased activity (138 +/- 34%), mass (29 +/- 7%), and mRNA (146 +/- 28%). Chenodeoxycholate feeding decreased activity (46 +/- 6%) and mRNA (26 +/- 12%). These data suggest rational regulation of CEH in response to changes in cholesterol flux through the liver. In primary hepatocytes, steady-state mRNA markedly decreased during 72-h cultures and addition of L-thyroxine and dexamethasone synergistically maintained mRNA levels near control values. Lovastatin increased mRNA levels by 103 +/- 15%. Taurocholate and phorbol 12-myristate 13-acetate suppressed mRNA (61 +/- 4% and 49 +/- 13%, respectively), suggesting that protein kinase C mediated effects of bile acids on CEH mRNA levels. These data suggest regulation of CEH by hormones and signal transduction in addition to changes in cholesterol flux.

Molecular cloning of the promoter for rat hepatic neutral cholesterol ester hydrolase: evidence for transcriptional regulation by sterols

Neutral cholesterol ester hydrolase is a key enzyme in regulating hepatic free cholesterol. Using the CEH specific cDNA sequence in the 5'-untranslated region as a primer, we amplified and cloned 1.3 Kb of promoter sequence upstream of the ATG initiation codon. Analysis of the sequence revealed the presence of a consensus GC-box, which can bind the positive transcription factor Sp1, 35 bases upstream from the transcription start site. Transcriptional regulation by agents perturbing cholesterol metabolism was studied in HepG2 cells by transient transfection assays of the promoter activity in deletion constructs linked to the luciferase reporter gene. Three functional sterol response sequences were identified at positions-92, -160, and -280 of the CEH promoter. The sterol response sequence at position -92 was shown to bind SREBP-2. Therefore, the CEH gene is similar to other genes involved in regulation of cholesterol homeostasis, in that it appears to be transcriptionally regulated by sterols.