Lethal mutagenesis of HIV with mutagenic nucleoside analogs

The human immunodeficiency virus (HIV) replicates its genome and mutates at exceptionally high rates. As a result, the virus is able to evade immunological and chemical antiviral agents. We tested the hypothesis that a further increase in the mutation rate by promutagenic nucleoside analogs would abolish viral replication. We evaluated deoxynucleoside analogs for lack of toxicity to human cells, incorporation by HIV reverse transcriptase, resistance to repair when incorporated into the DNA strand of an RNA.DNA hybrid, and mispairing at high frequency. Among the candidates tested, 5-hydroxydeoxycytidine (5-OH-dC) fulfilled these criteria. In seven of nine experiments, the presence of this analog resulted in the loss of viral replicative potential after 9-24 sequential passages of HIV in human CEM cells. In contrast, loss of viral replication was not observed in 28 control cultures passaged in the absence of the nucleoside analog, nor with other analogs tested. Sequence analysis of a portion of the HIV reverse transcriptase gene demonstrated a disproportionate increase in G --> A substitutions, mutations predicted to result from misincorporation of 5-OH-dC into the cDNA during reverse transcription. Thus, "lethal mutagenesis" driven by the class of deoxynucleoside analogs represented by 5-OH-dC could provide a new approach to treating HIV infections and, potentially, other viral infections.

Regulation of hippocampal neurogenesis in adulthood

A substantial number of new granule neurons are produced in the dentate gyrus in adulthood in a variety of mammalian species, including humans. Numerous studies have demonstrated that the production and survival of new hippocampal neurons can be enhanced or diminished by hormones and experience. Steroid hormones of the ovaries and adrenal glands have been shown to modulate the production of immature neurons by affecting the proliferation of granule cell precursors. Aversive experiences have been demonstrated to decrease the production of immature granule cells, whereas enriching experiences, including learning, have been shown to enhance the survival of new hippocampal cells. These studies indicate that adult-generated neurons represent a unique form of structural plasticity that can be regulated by the environment, and furthermore suggest that new neurons play an important role in hippocampal function.

N-methyl-D-aspartate receptor-mediated increase of neurogenesis in adult rat dentate gyrus following stroke

Neurogenesis in the adult rat dentate gyrus was studied following focal ischemic insults produced by middle cerebral artery occlusion (MCAO). Animals were subjected to either 30 min of MCAO, which causes damage confined to the striatum, or 2 h of MCAO, which leads to both striatal and cortical infarction. When compared to sham-operated rats, MCAO-rats showed a marked increase of the number of cells double-labelled for 5-bromo-2'-deoxyuridine-5'-monophosphate (BrdU; injected during 4-6 days postischemia) and neuronal-specific antigen (NeuN; a marker of postmitotic neurons) in the ipsilateral dentate granule cell layer and subgranular zone at 5 weeks following the 2 h insult. Only a modest and variable increase of BrdU-labelled cells was found after 30 min of MCAO. The enhanced neurogenesis was not dependent on cell death in the hippocampus, and its magnitude was not correlated to the degree of cortical damage. Systemic administration of the N-methyl-D-aspartate (NMDA) receptor blocker dizocilpine maleate (MK-801) completely suppressed the elevated neurogenesis following 2 h of MCAO. Our findings indicate that stroke leads to increased neurogenesis in the adult rat dentate gyrus through glutamatergic mechanisms acting on NMDA receptors. This modulatory effect may be mediated through changes in the levels of several growth factors, which occur after stroke, and could influence various regulatory steps of neurogenesis.

Skin delivery of 5-fluorouracil from ultradeformable and standard liposomes in-vitro

The potential use of ultradeformable and standard liposomes as skin drug delivery systems was investigated in-vitro. An improved experimental design gave a good measure for skin deposition of drug. This avoided the contamination that can occur due to incomplete washing of the donor before direct determination of the amount of drug in the skin. The design used aqueous ethanolic receptor which is believed to diffuse into skin, disrupting deposited liposomes (if any) and thus releasing both bound and free drug. The receptor fluid was refined by testing different concentrations of ethanol. The applied dose was also optimized. Using the improved design and the optimum dose, an ultradeformable formulation was compared with four traditional liposomes for skin delivery of 5-fluorouracil (5-FU). The best receptor was 50% aqueous ethanol and the optimum dose was 20 microL. The ultradeformable formulation was superior to standard liposomes in the skin delivery of 5-FU. Of the traditional liposomes, the non-rigid preparation was the best. However, stabilization of the liposome membrane with cholesterol abolished the benefit of this non-rigid preparation. It was concluded that ultradeformable vesicles are promising agents for skin delivery of drugs.

Role of tumor necrosis factor receptor 2 (TNFR2) in colonic epithelial hyperplasia and chronic intestinal inflammation in mice

BACKGROUND & AIMS

Tumor necrosis factor (TNF) induces multiple effects including cell proliferation and death by ligation with TNF receptor type II (TNFR2). We studied the role of TNFR2 in chronic inflammation-induced colonic epithelial alteration.

METHODS

TNFR2 expression in colonic epithelial cells (CECs) was assessed by ribonuclease protection assay (RPA) and immunohistochemistry (IHC) in patients with inflammatory bowel disease (IBD) and murine colitis models. TNFR2 expression was also analyzed using COLO205 cells. The role of TNFR2 in colonic epithelial homeostasis was examined by generating interleukin 6-deficient TCR alpha KO (alpha IL-6DKO) or TNFR2-deficient TCR alpha (alpha TNFR2DKO) mice.

RESULTS

TNFR2 expression was up-regulated in CEC in both human ulcerative colitis and Crohn's disease. In vitro studies showed that TNFR2 expression was up-regulated by a cooperative effect of key proinflammatory cytokines. By RPA, the increased expression of TNFR2 was detectable in TCR alpha KO mice with colitis compared with TCR alpha KO mice without colitis or wild-type mice. In alpha IL-6DKO mice, TNFR2 expression, proliferation, and nuclear factor kappa B activation of CECs were markedly reduced compared with TCR alpha KO mice. alpha TNFR2 mice also showed significantly less colonic epithelial proliferation compared with TCR alpha KO mice.

CONCLUSIONS

Expression of TNFR2 is consistently increased on CECs in both murine colitis models as well as patients with IBD. TNFR2 may play an important role in colonic inflammation-associated alteration in the intestinal epithelium.

Expression of Notch-1 and its ligand Jagged-1 in rat liver during liver regeneration

The Notch/Jagged signaling pathway is important for cellular differentiation and proliferation. Its dysfunction is associated with human pathologies in several tissues including liver. Point mutations in Jagged-1 gene are the cause for Alagille syndrome, associated with paucity of intrahepatic bile ducts. To determine the putative role of the trans-membrane receptor Notch and its ligand Jagged-1 in liver regeneration, we investigated the expression of Notch and Jagged-1 in rat liver following 2/3 partial hepatectomy. Immunohistochemical staining of normal rat liver showed that Notch was expressed in hepatocytes, bile duct cells and endothelial cells, whereas Jagged-1 was expressed in bile duct cells and hepatocytes. Both Notch-1 and Jagged-1 proteins were upregulated in hepatocytes after partial hepatectomy up to day 4. After partial hepatectomy, nuclear translocation of the intracellular cytoplasmic domain of Notch (NICD) increased and peaked within 15 minutes, indicating the activation of Notch. Expression of the Notch-dependent target gene (HES-1) expression increased within 30-60 minutes. Addition of recombinant Jagged-1 protein to primary cultures of hepatocytes stimulated hepatocyte DNA synthesis. Furthermore, injection of silencing RNA for Notch and Jagged-1 to livers 2 days before partial hepatectomy significantly suppressed proliferation of hepatocytes at days 2 to 4 of the regenerative response. In conclusion, Notch/Jagged signaling pathway is activated during liver regeneration and is potentially contributing to signals affecting cell growth and differentiation.

Pharmacogenetics during standardised initiation of thiopurine treatment in inflammatory bowel disease

BACKGROUND

Firm recommendations about the way thiopurine drugs are introduced and the use of thiopurine methyltransferase (TPMT) and metabolite measurements during treatment in inflammatory bowel disease (IBD) are lacking.

AIM

To evaluate pharmacokinetics and tolerance after initiation of thiopurine treatment with a fixed dosing schedule in patients with IBD.

PATIENTS

60 consecutive patients with Crohn's disease (n = 33) or ulcerative colitis (n = 27) were included in a 20 week open, prospective study.

METHODS

Thiopurine treatment was introduced using a predefined dose escalation schedule, reaching a daily target dose at week 3 of 2.5 mg azathioprine or 1.25 mg 6-mercaptopurine per kg body weight. TPMT and ITPA genotypes, TPMT activity, TPMT gene expression, and thiopurine metabolites were determined. Clinical outcome and occurrence of adverse events were monitored.

RESULTS

27 patients completed the study per protocol, while 33 were withdrawn (early protocol violation (n = 5), TPMT deficiency (n = 1), thiopurine related adverse events (n = 27)); 67% of patients with adverse events tolerated long term treatment on a lower dose (median 1.32 mg azathioprine/kg body weight). TPMT activity did not change during the 20 week course of the study but a significant decrease in TPMT gene expression was found (TPMT/huCYC ratio; p = 0.02). Patients with meTIMP concentrations >11,450 pmol/8 x 10(8) red blood cells during steady state at week 5 had an increased risk of developing myelotoxicity (odds ratio = 45.0; p = 0.015).

CONCLUSIONS

After initiation of thiopurine treatment using a fixed dosing schedule, no general induction of TPMT enzyme activity occurred, though TPMT gene expression decreased. The development of different types of toxicity was unpredictable, but we found that measurement of meTIMP early in the steady state phase helped to identify patients at risk of developing myelotoxicity.

Metabolic and mitogenic effects of IGF-I and insulin on muscle cells of rainbow trout

The relative function of IGF-I and insulin on fish muscle metabolism and growth has been investigated by the isolation and culture at different stages (myoblasts at day 1, myocytes at day 4, and myotubes at day 10) of rainbow trout muscle cells. This in vitro model avoids interactions with endogenous peptides, which could interfere with the muscle response. In these cells, the effects of IGF-I and insulin on cell proliferation, 2-deoxyglucose (2-DG), and l-alanine uptake at different development stages, and the use of inhibitors were studied and quantified. Insulin (10-1,000 nM) and IGF-I (10-100 nM) stimulated 2-DG uptake in trout myocytes at day 4 in a similar manner (maximum of 124% for insulin and of 142% for IGF-I), and this stimulation increased when cells differentiated to myotubes (maximum for IGF-I of 193%). When incubating the cells with PD-98059 and especially cytochalasin B, a reduction in 2-DG uptake was observed, suggesting that glucose transport takes place through specific facilitative transporters. IGF-I (1-100 nM) stimulated the l-alanine uptake in myocytes at day 4 (maximum of 239%), reaching higher values of stimulation than insulin (100-1,000 nM) (maximum of 160%). This stimulation decreased when cells developed to myotubes at day 10 (118% for IGF-I and 114% for insulin). IGF-I (0.125-25 nM) had a significant effect on myoblast proliferation, measured by thymidine incorporation (maximum of 170%), and required the presence of 2-5% fetal serum (FBS) to promote thymidine uptake. On the other hand, insulin was totally ineffective in stimulating thymidine uptake. We conclude that IGF-I is more effective than insulin in stimulating glucose and alanine uptake in rainbow trout myosatellite cells and that the degree of stimulation changes when cells differentiate to myotubes. IGF-I stimulates cell proliferation in this model of muscle in vitro and insulin does not. These results indicate the important role of IGF-I on growth and metabolism of fish muscle.

Epiregulin, a novel member of the epidermal growth factor family, is an autocrine growth factor in normal human keratinocytes

Epiregulin is a new member of the epidermal growth factor (EGF) family purified from conditioned medium of NIH-3T3 clone T7. Some EGF family growth factors play essential roles in human keratinocytes in an autocrine manner. We show here that epiregulin is another autocrine growth factor for human keratinocytes. Epiregulin stimulated human keratinocyte proliferation under both subconfluent and confluent culture conditions in the absence of exogenous EGF family growth factors. Immunoprecipitation of [(35)S]methionine-labeled conditioned medium revealed a 5-kDa band corresponding to epiregulin. Northern blot analysis detected a 4. 8-kilobase transcript of epiregulin, and the addition of epiregulin up-regulated epiregulin mRNA synthesis. Furthermore, an anti-epiregulin blocking antibody reduced DNA synthesis by 25%. Epiregulin up-regulated the mRNA levels of heparin-binding EGF-like growth factor (HB-EGF), amphiregulin, and TGF-alpha. In turn, the addition of EGF, HB-EGF, amphiregulin, and TGF-alpha increased epiregulin mRNA levels. These results demonstrate that epiregulin acts as an autocrine growth factor in human epidermal keratinocytes and is part of auto- and cross-induction mechanisms involving HB-EGF, amphiregulin, and TGF-alpha. The mRNA expression profile resulting from induction of differentiation with high calcium and fetal calf serum revealed the differential expression of epiregulin, HB-EGF, amphiregulin, and TGF-alpha in keratinocytes. This indicates that these four growth factors have distinct, non-redundant biological functions.

Pharmacokinetics and pharmacodynamics of methotrexate in non-neoplastic diseases

Low dose pulse methotrexate (LDMTX) therapy has become effective in the treatment of autoimmune and lymphoproliferative diseases. The pharmacokinetics of LDMTX is individually highly variable, resulting in a different systemic exposure to the drug and a variable therapeutic/toxic effect in patients. The improvements and exacerbations of disease activity in relation to the introductions and discontinuations of LDMTX therapy suggest the possible immunosuppresive and anti-inflammatory properties of the drug. Because of a strong correlation between the drug pharmacokinetics and the therapeutic outcomes (pharmacodynamics), it seems to be possible to individualise the LDMTX therapy according to the results of pharmacokinetic/pharmacodynamic analysis. In the case of psoriasis, pharmacokinetic/pharmacodynamic analysis in our local study revealed a highly significant inverse relationship between PASI (expressed as a percent of the initial value) and a steady-state AUC(MTX) (area under the curve of methotrexate plasma concentrations; r(8) = -0.65, p < 0.001). The considerable inter-individual variability and low intra-individual variability in MTX pharmacokinetics, supports a role for therapeutic monitoring and dose individualisation at the start of pharmacotherapy. The results of this study suggest that a steady-state AUC(MTX) value of 700 nmol x h/L and higher are associated with a significantly better success rate of antipsoriatic therapy than lower values. The preliminary results in our follow-up study suggest the statistically higher incidence of unwanted effects depending on maximum plasma concentration of the drug. Moreover, statistically significant correlation was found between the toxic effects and exposure to the drug regarding methotrexate plasma concentrations and intracellular storage in erythrocytes. However, the data are still in the process of being completed and are not yet published.

Long-term stabilization of vein graft wall architecture and prolonged resistance to experimental atherosclerosis after E2F decoy oligonucleotide gene therapy

OBJECTIVE

We tested the hypothesis that a single intraoperative transfection of rabbit vein grafts with a decoy oligonucleotide that blocks cell-cycle gene transactivation by the transcription factor E2F induces long-term stable adaptation that involves medial hypertrophy and a resistance to neointimal hyperplasia and atherosclerosis.

METHODS

Jugular vein to carotid artery interposition vein grafts in hypercholesterolemic rabbits were treated, using pressure-mediated delivery, with either E2F decoy oligonucleotide, scrambled oligonucleotide, or vehicle alone. E2F decoy inhibition of cell-cycle gene expression was determined by measuring proliferating cell nuclear antigen upregulation and bromodeoxyuridine incorporation in vascular smooth muscle cells. Neointimal hyperplasia and atherosclerosis were compared between groups at 6 months after operation. Wall stress was derived from the ratio of luminal radius to wall thickness. Normal rabbits exposed to 6 weeks of diet-induced hypercholesterolemia starting 6 months after operation were analyzed in the same manner.

RESULTS

The E2F decoy oligonucleotide, but not scrambled oligonucleotide or vehicle alone, inhibited proliferating cell nuclear antigen expression and smooth muscle cell proliferation. Furthermore, this manipulation of cell-cycle gene expression yielded an inhibition of neointimal hyperplasia and atherosclerotic plaque formation throughout the 6 months of cholesterol feeding. In normocholesterolemic rabbits, vehicle-treated and scrambled oligonucleotide-treated vein grafts remain susceptible to diet-induced atherosclerosis as well, whereas resistance to this disease induction remained stable in genetically engineered grafts.

CONCLUSION

A single intraoperative pressure-mediated delivery of E2F decoy effectively provides vein grafts with long-term resistance to neointimal hyperplasia and atherosclerosis. These findings suggest that long-term reduction in human vein graft failure rates may be feasible with this ex vivo gene therapy approach.

Astrocytes respond to hypoxia by increasing glycolytic capacity

Astrocytes cope more readily with hypoxic insults than do neurons. We hypothesized that astrocytes can upregulate their glycolytic capacity, allowing anaerobic glycolysis to provide sufficient ATP for cell survival as well as for carrying out critical functions such as taking up glutamate. To test this hypothesis, astrocytes were subjected to hypoxia for 5 hr. Lactate dehydrogenase (LDH) and pyruvate kinase activities increased 3- to 4-fold. Examination of LDH isoenzyme patterns determined that it was the anaerobic isoenzymes that were upregulated. To determine whether increase in enzyme activity translates into increased glycolytic capacity, astrocytes were subjected to varying time periods of hypoxia, and glucose uptake was measured under conditions where astrocytes were forced to consume more ATP. This demonstrated that 8 hr of hypoxia resulted in a doubling of glycolytic capacity. We suggest that how quickly astrocytes upregulate glycolytic capacity may determine whether or not neurons within the stroke penumbra survive.

Inhibition of glucose transport in PC12 cells by the atypical antipsychotic drugs risperidone and clozapine, and structural analogs of clozapine

Treatment of schizophrenics with some antipsychotic drugs has been associated with an increased incidence of hyperglycemia and new-onset type 2 diabetes. Some of these drugs also inhibit glucose transport in rat pheochromocytoma (PC12) cells. The current study was designed to examine the effects of the atypical antipsychotic drugs--risperidone, clozapine and analogs of clozapine on glucose uptake in PC12 cells. Glucose transport was measured in cells incubated with vehicle or drug over a range of concentrations (0.2-100 microM). Uptake of 3H-2-deoxyglucose was measured over 5 min and the data were normalized on the basis of total cell protein. Risperidone and clozapine inhibited glucose transport in a dose-dependent fashion with IC(50)'s estimated to be 35 and 20 microM, respectively. The clozapine metabolite, desmethylclozapine, was considerably more potent than the parent drug, whereas clozapine N-oxide was essentially inactive. The structural analogs of clozapine, loxapine and amoxapine, both inhibited glucose transport with amoxapine being the least potent. The ability of the drugs to inhibit glucose transport was significantly decreased by including 2-deoxyglucose (5 mM) in the uptake medium. Schild analysis of the glucose sensitivity of clozapine, loxapine and risperidone indicated that 2-deoxyglucose non-competitively antagonized the inhibitory effects of these drugs. Moreover, clozapine and fluphenazine inhibited glucose transport in the rat muscle cell line, L6. These studies suggest that the drugs may block glucose accumulation directly at the level of the glucose transporter (GLUT) protein in cells derived from both peripheral and brain tissue. Furthermore, this work may provide clues about how the antipsychotic drugs produce hyperglycemia in vivo.

Immunocytochemical and physiological characterization of a population of cultured human neural precursors

Human neural precursor cells (HNPC) have recently become commercially available. In an effort to determine the usefulness of these cells for in vitro studies, we have grown cultured HNPCs (cHNPCs) according to the supplier specifications. Here we report our characterization of cHNPCs under nondifferentiating and differentiating growth conditions and make a comparison to primary HNPCs (pHNPCs) obtained at the same developmental time point from a different commercial supplier. We found that under nondifferentiating conditions, cHNPCs expressed nestin, divided rapidly, expressed few markers of differentiated cells, and displayed both 4-aminopyridine (4-AP)-sensitive and delayed-rectifier type K(+) currents. No inward currents were observed. On changing to differentiating culture conditions, a majority of the cells expressed neuronal markers, did not divide, expressed inward and outward time- and voltage-dependent currents, and responded to the application of the neurotransmitters acetylcholine and glutamate. The outward current densities were indistinguishable from those in undifferentiated cells. The inward currents included TTX-sensitive and -resistant Na(+) currents, sustained Ca(2+) currents, and an inwardly rectifying K(+) current. Comparison of the properties of differentiated cells from cHNPCs with neurons obtained from primary fetal cultures (pHNPCs) revealed two major differences: the differentiated cHNPCs did not express embryonic neural cell adhesion molecule (E-NCAM) immunoreactivity but did co-express GFAP immunoreactivity. The co-expression of neuronal and glial markers was likely due to the growth of cells in serum containing medium as the pHNPCs that were never exposed to serum did express E-NCAM and did not co-express glial fibrillary acidic protein (GFAP). The relevance of these results is discussed and compared with results from other neuronal progenitor populations and cultured human neuronal cells.

Ex vivo application of carbon monoxide in University of Wisconsin solution to prevent intestinal cold ischemia/reperfusion injury

Carbon monoxide (CO), a byproduct of heme catalysis, was shown to have potent cytoprotective and anti-inflammatory effects. In vivo recipient CO inhalation at low concentrations prevented ischemia/reperfusion (I/R) injury associated with small intestinal transplantation (SITx). This study examined whether ex vivo delivery of CO in University of Wisconsin (UW) solution could ameliorate intestinal I/R injury. Orthotopic syngenic SITx was performed in Lewis rats after 6 h cold preservation in control UW or UW that was bubbled with CO gas (0.1-5%) (CO-UW). Recipient survival with intestinal grafts preserved in 5%, but not 0.1%, CO-UW improved to 86.7% (13/15) from 53% (9/17) with control UW. At 3 h after SITx, grafts stored in 5% CO-UW showed improved intestinal barrier function, less mucosal denudation and reduced inflammatory mediator upregulation compared to those in control UW. Preservation in CO-UW associated with reduced vascular resistance (end preservation), increased graft cyclic guanosine monophosphate levels (1 h), and improved graft blood flow (1 h). Protective effects of CO-UW were reversed by ODQ, an inhibitor of soluble guanylyl cyclase. In vitro culture experiment also showed better preservation of vascular endothelial cells with CO-UW. The study suggests that ex vivo CO delivery into UW solution would be a simple and innovative therapeutic strategy to prevent transplant-induced I/R injury.

The interaction among glucose transport, hexokinase, and glucose-6-phosphatase with respect to 3H-2-deoxyglucose retention in murine tumor models

The development of new diagnostic/therapeutic modalities for cancer requires a specific understanding of how tumors differ from normal tissues. Though the key components involved in the selective accumulation of 2-deoxy-D-glucose (2-DG) analogs in tumors are known, the relative importance of each is controversial. For this reason glucose transport protein (GLUT) density, hexokinase/glucose-6-phosphatase (GP) activity, and 2-DG biodistribution were measured together in four tumor models and normal murine tissues. Direct binding studies with 3H-cytochalasin B showed that GLUT density was elevated 20-fold in LX-1 tumors. Immunohistochemically in all tumors, the expression of GLUT-1 was highest in the necrotic/ perinecrotic foci and similar in cells not adjacent to necrotic foci. As the retention of 3H-2-DG was similar in all tumors, these data suggest that the GLUT-1 in perinecrotic tumor cells were not rate limiting for 3H-2-DG uptake. Kidney, liver, and lung had high GP activity and rapid clearance of 3H-2-DG. Sodium orthovanadate (5 mumol), a GP inhibitor, increased the concentration of 3H-2-DG in these tissues, suggesting that GP is a rate-limiting enzyme for 3H-2-DG clearance. All tumor homogenates had low GP activity, and hexokinase activity was not elevated compared to normal tissues. Thus, in the tumors studied, the selective accumulation of 3H-2-DG consistently occurred in the absence of significant GP activity without the marked overexpression of hexokinase or GLUT.

TGF-beta 1 stimulates glucose uptake by enhancing GLUT1 expression in mesangial cells

BACKGROUND

An increase in the expression of transforming growth factor-beta 1 (TGF-beta 1) has been proposed to play an important role in the excessive production of extracellular matrix (ECM) proteins seen in diabetes. Because the linkage between glucose metabolism and ECM protein production was found in mesangial cells overexpressed with the brain-type glucose transporter (GLUT1), we hypothesized that TGF-beta 1 could affect glucose metabolism.

METHODS

To prove this hypothesis, we examined the effect of TGF-beta 1 on glucose uptake, the first step of glucose metabolism, in mesangial cells. 2-Deoxy-D-glucose (2DOG) uptake and the expression of GLUT1 were measured in mesangial cells exposed to various concentrations of TGF-beta 1. The kinetic constants were determined using 2DOG and 3-O-methyl-D-glucose (3OMG). The effect of anti-TGF-beta neutralizing antibody on 2DOG uptake and GLUT1 mRNA was also examined in mesangial cells cultured under high-glucose (22.2 mM) conditions for 72 hours.

RESULTS

TGF-beta 1 stimulated 2DOG uptake in mesangial cells by approximately 2.5-fold in a dose- (1.25 ng/ml maximum) and time-dependent manner, with a peak stimulation at nine hours. The increase in 2DOG uptake by TGF-beta 1 was completely abolished by the addition of 1 microgram/ml cycloheximide, and kinetic analysis of 2DOG or 3OMG uptake revealed an increase in Vmax by TGF-beta 1. Furthermore, TGF-beta 1 enhanced the expression of GLUT1 mRNA from one hour, followed by an enhancement of the expression of GLUT1 protein at nine hours. Finally, 2DOG uptake was significantly enhanced in cells cultured under high-glucose (22.2 mM) conditions as compared with that in cells under normal glucose (5.6 mM) conditions, and this increase in 2DOG uptake in cells under high-glucose conditions was inhibited by the addition of anti-TGF-beta neutralizing antibody.

CONCLUSIONS

TGF-beta 1 stimulates glucose uptake by enhancing the expression of GLUT1 in mesangial cells, which leads to the acceleration of intracellular metabolic abnormalities in diabetes.

Electrorepulsion versus electroosmosis: effect of pH on the iontophoretic flux of 5-fluorouracil

PURPOSE

To delineate the contributions of electrorepulsion and electroosmosis to the iontophoretic flux of 5-FU across porcine skin in vitro. Also, the isoelectric point (pI) of the skin model was determined.

METHODS

The electrotransport of 5-FU, anode-to-cathode ("anodal") and cathode-to-anode ("cathodal") was determined as a function of the pH of the electrolyte bathing the skin.

RESULTS

At pH 8.5, the drug (pKa approximately 8) is negatively charged and "cathodal", viz. electrorepulsive, transport is much greater than that in the opposite direction. At pH 7.4, where approximately 25% of 5-FU is charged, electrorepulsive and electroosmotic ("anodal") fluxes are balanced. Decreasing the pH to 6, and then 5, reduces the percentage of ionized 5-FU such that "anodal" electroosmosis dominates across the negatively-charged membrane. But, at pH 4, "anodal" and "cathodal" fluxes are again equal suggesting neutralization of the skin (i.e., pI approximately 4). This is confirmed at pH 3, where "cathodal" electroosmosis dominates across the now net-positively charged barrier.

CONCLUSIONS

Electrotransport is sensitive, mechanistically, to the properties of the permeant and of the skin; interactions of, for example, the drug or constituents of a formulation, that alter the barrier's net charge, can affect iontophoretic delivery. The pI of porcine ear skin is approximately 4.

Label-retaining cells in the rat pancreas: location and differentiation potential in vitro

Islets of Langerhans are micro-organs scattered throughout the pancreas that contain insulin-producing cells, called beta-cells. Although new light has been recently shed on beta-cell development, information on the phenotype and location of beta-stem cells remains scarce. Here, we provide evidence that beta-stem cells are slow-cycling cells located within and around the islets of Langerhans. First, using a bromodeoxyuridine (BrdU) pulse/chase approach, we detected BrdU-retaining cells in vivo in the islet area of rat pancreata. These cells were negative for endocrine markers but expressed Pdx1, a marker for pancreatic stem cells. Next, using an in vitro model that mimicked endocrine cell development, we found that BrdU-retaining cells were capable of differentiating into beta-cells. Taken together, these observations demonstrate that BrdU retention is a property of beta-stem cells.

Genetic selection of mice for high voluntary wheel running: effect on skeletal muscle glucose uptake

Effects of genetic selection for high wheel-running activity (17th generation) and access to running wheels on skeletal muscle glucose uptake were studied in mice with the following treatments for 8 wk: 1) access to unlocked wheels; 2) same as 1, but wheels locked 48 h before glucose uptake measurement; or 3) wheels always locked. Selected mice ran more than random-bred (nonselected) mice (8-wk mean +/- SE = 8,243 +/- 711 vs. 3,719 +/- 233 revolutions/day). Body weight was 5-13% lower for selected vs. nonselected groups. Fat pad/body weight was ~40% lower for selected vs. nonselected and unlocked vs. locked groups. Insulin-stimulated glucose uptake and fat pad/body weight were inversely correlated for isolated soleus (r = -0.333; P < 0.005) but not extensor digitorum longus (EDL) or epitrochlearis muscles. Insulin-stimulated glucose uptake was higher in EDL (P < 0.02) for selected vs. nonselected mice. Glucose uptake did not differ by wheel group, and amount of running did not correlate with glucose uptake for any muscle. Wheel running by mice did not enhance subsequent glucose uptake by isolated muscles.

Dystrophic psoriatic fingernails treated with 1% 5-fluorouracil in a nail penetration-enhancing vehicle: a double-blind study

BACKGROUND

Topically applied nail therapeutics need to permeate the nail plate to reach the nail bed or nail matrix and exert their potential beneficial effect at these locations to obtain a therapeutic benefit. So far only topically applied 5-fluorouracil on affected nails of psoriatic patients has been shown to produce a notable clearance. Vehicle formulations enhancing nail permeation processes are thought to increase the concentration of the active agent and therefore therapeutic efficacy, possibly enabling the use of a low concentration of the active agent thereby lowering the incidence of adverse effects.

OBJECTIVE

This study was designed to verify whether a recently developed nail penetration enhancer in a lotion formulation, Belanyx((R)) (urea, propylene glycol), improves the efficacy of a low concentration of 5-fluorouracil (1%) in psoriatic fingernail lesions.

METHODS

In a randomised, double-blind, left-right study the efficacy of 1% 5-fluorouracil in the Belanyx vehicle was compared to the vehicle preparation Belanyx in dystrophic fingernails of 57 psoriatic patients. Both preparations were applied in a once daily regimen for 12 weeks. Responses and adverse effects of one selected target nail were recorded at screening, at baseline and at weeks 2, 4, 8 and 12 of treatment with a final assessment at week 16: 4 weeks after the end of treatment. As parameter of efficacy was chosen the total nail area severity (NAS) score, consisting of the separate parameters nail pitting area, number of nail pits, subungual keratosis, onycholysis, oil spots and the various scores of overall improvement.

RESULTS

The efficacy of 1% 5-fluorouracil in lotion and that of the vehicle in suppressing the parameters of dystrophy were shown to be similar at the end of treatment (p = 0.063) or follow-up (p = 0.130). Both preparations produced statistically significant improvements (p </= 0.05) for almost all assessed parameters after 12 weeks of treatment and after the 4 weeks of follow-up. For Belanyx lotion this applied to the nail pitting area, the number of nail pits, subungual keratosis, onycholysis and oil spots. The investigators' and patients' opinion of overall improvement of severity as well as the total NAS score of one target nail likewise showed a statistically significant improvement at the end of treatment and at the end of the observation period (p </= 0.05). With the 1% 5-fluorouracil lotion the same statistically significant improvements were obtained in all of the assessed symptoms with the exception of the number of pits and onycholysis at week 12 and week 16. Possible treatment-related adverse effects were established in 6 patients showing inflammation and infection (3 patients) or discoloration (5 patients); 3 patients on 5-fluorouracil lotion showed onycholysis.

CONCLUSION

Addition of 1% 5-fluorouracil to the nail permeation enhancer Belanyx does not increase the efficacy of the active agent in psoriatic nail dystrophy of this study population. The obtained results also suggest that Belanyx lotion can be used in this indication since it has shown a favourable efficacy-safety ratio.

Soluble guanylate cyclase-alpha1 deficiency selectively inhibits the pulmonary vasodilator response to nitric oxide and increases the pulmonary vascular remodeling response to chronic hypoxia

BACKGROUND

Nitric oxide (NO) activates soluble guanylate cyclase (sGC), a heterodimer composed of alpha- and beta-subunits, to produce cGMP. NO reduces pulmonary vascular remodeling, but the role of sGC in vascular responses to acute and chronic hypoxia remains incompletely elucidated. We therefore studied pulmonary vascular responses to acute and chronic hypoxia in wild-type (WT) mice and mice with a nonfunctional alpha1-subunit (sGCalpha1-/-).

METHODS AND RESULTS

sGCalpha1-/- mice had significantly reduced lung sGC activity and vasodilator-stimulated phosphoprotein phosphorylation. Right ventricular systolic pressure did not differ between genotypes at baseline and increased similarly in WT (22+/-2 to 34+/-2 mm Hg) and sGCalpha1-/- (23+/-2 to 34+/-1 mm Hg) mice in response to acute hypoxia. Inhaled NO (40 ppm) blunted the increase in right ventricular systolic pressure in WT mice (22+/-2 to 24+/-2 mm Hg, P<0.01 versus hypoxia without NO) but not in sGCalpha1-/- mice (22+/-1 to 33+/-1 mm Hg) and was accompanied by a significant rise in lung cGMP content only in WT mice. In contrast, the NO-donor sodium nitroprusside (1.5 mg/kg) decreased systemic blood pressure similarly in awake WT and sGCalpha1-/- mice as measured by telemetry (-37+/-2 versus -42+/-4 mm Hg). After 3 weeks of hypoxia, the increases in right ventricular systolic pressure, right ventricular hypertrophy, and muscularization of intra-acinar pulmonary vessels were 43%, 135%, and 46% greater, respectively, in sGCalpha1-/- than in WT mice (P<0.01). Increased remodeling in sGCalpha1-/- mice was associated with an increased frequency of 5'-bromo-deoxyuridine-positive vessels after 1 and 3 weeks (P<0.01 versus WT).

CONCLUSIONS

Deficiency of sGCalpha1 does not alter hypoxic pulmonary vasoconstriction. sGCalpha1 is essential for NO-mediated pulmonary vasodilation and limits chronic hypoxia-induced pulmonary vascular remodeling.

c-Fms tyrosine 559 is a major mediator of M-CSF-induced proliferation of primary macrophages

The molecular mechanisms by which binding of monocyte/macrophage colony-stimulating factor to its receptor c-Fms promotes replication in primary macrophages are incompletely understood, as all previous studies involved overexpression of receptor mutants in transformed cells not endogenously expressing the receptor. To address this issue we retrovirally expressed, in bone marrow-derived macrophages, a chimeric receptor containing a range of tyrosine to phenylalanine mutations in the c-Fms cytoplasmic tail. We measured incorporation of bromodeoxyuridine as a marker of proliferation and phosphorylation of ERKs, Akt, and the receptor itself. Our data indicate that tyrosine 559 is the major mediator of receptor activation and cell death, intracellular signaling, and cell proliferation and that the tyrosine residues at positions 697 and 807 play lesser roles in these events. Importantly, we find that activation of the ERK and Akt pathways is necessary but not sufficient for induction of macrophage proliferation. Using specific small molecule inhibitors we find that a combination of the Src family kinase, phosphatidylinositol 3-kinase/Akt, phospholipase C, and ERK pathways mediates macrophage proliferation in response to M-CSF.

A detailed analysis of cyclin A accumulation at the G(1)/S border in normal and transformed cells

The temporal relationship between cyclin A accumulation and the onset of DNA replication was analyzed in detail. Five untransformed and nine transformed asynchronously growing cell cultures were investigated using a triple immunofluorescence staining protocol combined with computerized evaluation of staining intensities in individual cells. The simultaneous staining of BrdU, cyclin A, and cyclin E made it possible to determine the cell cycle position of each cell investigated. Cells at the G(1)/S border were identified on the basis of cyclin E content and were further analyzed with respect to cyclin A and BrdU content. A method was developed to calculate objective thresholds defining the highest staining intensity found in the negative cells in the population. Using the thresholds we could distinguish cells with minute amounts of cyclin A and BrdU from truly negative cells. We show that the onset of cyclin A accumulation and the start of DNA replication occurs at the same time, or deviating by a few minutes at the most. We also show that cyclin A accumulates continuously during S. This study clearly demonstrates that nuclear cyclin A can be used as a reliable marker for the S and G(2) phases in both normal and transformed interphase cells.

Metabolic and functional mapping of the neural network subserving inferior collicular seizure generalization

The sensory-motor portion of the inferior collicular cortex is capable of seizure genesis that is characterized initially by coincident wild running behaviors and localized electrographic afterdischarge. With repeated stimulations, this seizure activity spreads into the forebrain, producing generalized tonic-clonic or myoclonic seizure activity. In order to characterize the neural network subserving this caudal-rostral seizure generalization, three mapping techniques were used: 2-deoxyglucose (2-DG) utilization, c-fos expression and local anesthetic microinjection. Kindled seizure generalization from the inferior collicular cortex produced a global increase in 2-DG accumulation, while relative 2-DG increases were found in the inferior collicular cortex, dorsal lateral lemniscus, dorsal central gray, peripeduncular nucleus, medial geniculate nucleus, substantia nigra, entopeduncular nucleus, ventroposterior and centromedian thalamus and tenia tectum, as well as the perirhinal, somatosensory and frontal cortices. Kindled seizure generalization also increased c-fos-like immunoreactivity (FLI) in the inferior collicular cortex, cuneiform nucleus, dorsal lateral nucleus of the lateral lemniscus, peripeduncular nucleus, caudal central gray, dentate gyrus of the hippocampus, rhinal fissure area of the perirhinal cortex and the frontal cortex. Microinjections of procaine into the amygdala, perirhinal cortex, entopeduncular nucleus, substantia nigra, peripeduncular nucleus, dorsal central gray, and pontine reticular nucleus all prevented generalized seizure behaviors, but had no effect on the wild running seizures. Conversely, procaine microinjection into the area of the cuneiform nucleus/pedunculopontine tegmental nucleus prevented the wild running seizure but did not block the generalized seizure activity. Neither wild running, nor generalized seizures were altered following procaine microinjections into the anterior thalamus, sub-thalamus, lateral hypothalamus, hippocampus or deep superior colliculus. Thus, specific forebrain sites form a widespread neural network that mediates the generalization of seizure activity from the inferior collicular cortex into the forebrain.