BACKGROUND

In animal studies of radiofrequency ablation, lesion sizes plateau as the maximum lesion size is reached for an ablation. Lesion parameters are not available in clinical ablations, but preclinical work suggests that these correlate with impedance drop and electrogram attenuation. Characterization of the relationships between catheter contact force, ablation duration, and these surrogate markers of lesion formation may allow us to define targets for effective ablation.

RESULTS

Fifteen patients undergoing first-time radiofrequency ablation for nonparoxysmal atrial fibrillation were studied. All were in atrial fibrillation at the time of the procedure. Ablations were performed with an irrigated-tip contact force-sensing catheter in temperature-controlled mode (temperature limited to 48°C, power to 30 W). Included were 285 left atrial static ablations, 247 with additional impedance data. The ablation force time integral (FTI) correlated with the attenuation of the electrogram with ablation (Spearman ρ, -0.14; P=0.02): the relationship plateauing from 500 g·s, a reduction in the electrogram amplitude of 20%. The FTI also correlated with the impedance drop during ablation (Spearman ρ, 0.79; P<0.0005): the relationship was logarithmic, the reduction in the impedance with an increasing FTI also plateauing from 500 g·s, an impedance drop of 7.5%. The ablation duration affected the impedance drop at an FTI if the duration was <10 s. Beyond this time point, the FTI achieved rather than the ablation duration or mean contact force applied determined the impedance drop.

CONCLUSIONS

During nonparoxysmal atrial fibrillation ablation, an FTI of 500 g·s should be targeted with ablation duration of ≥10 s. Clinical Trials Registration- URL: http://clinicaltrials.gov/. Unique Identifier: NCT01587404.

Polycystic ovary syndrome (PCOS) is characterized by ovarian enlargement, theca-interstitial hyperplasia, and increased androgen production by theca cells. Previously, our group has demonstrated that statins (competitive inhibitors of 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase, a rate-limiting step of the mevalonate pathway) reduce proliferation of theca-interstitial cells in vitro and decrease serum androgen levels in women with PCOS. The present study evaluated the effect of simvastatin on rat ovarian theca-interstitial cell steroidogenesis. Because actions of statins may be due to reduced cholesterol availability and/or isoprenylation of proteins, the present study also investigated whether steroidogenesis was affected by cell- and mitochondrion-permeable 22-hydroxycholesterol, isoprenylation substrates (farnesyl-pyrophosphate [FPP] and geranylgeranyl-pyrophosphate [GGPP]), as well as selective inhibitors of farnesyltransferase (FTI) and geranylgeranyltransferase (GGTI). Theca-interstitial cells were cultured for 12, 24, and 48 h with or without simvastatin, GGPP, FPP, FTI, GGTI, and/or 22-hydroxycholesterol. Simvastatin decreased androgen levels in a time- and concentration-dependent fashion. This inhibitory effect correlated with a decrease in mRNA levels of Cyp17a1, the gene encoding the key enzyme regulating androgen biosynthesis. After 48 h, GGPP alone and FPP alone had no effect on Cyp17a1 mRNA expression; however, the inhibitory action of simvastatin was partly abrogated by both GGPP and FPP. The present findings indicate that statin-induced reduction of androgen levels is likely due, at least in part, to the inhibition of isoprenylation, resulting in decreased expression of CYP17A1.

Cyclic AMP inhibits the expression of nitric oxide synthase (Harbrecht et al., 1995 [1]) in hepatocytes but the mechanism for this effect is incompletely understood. Cyclic AMP can activate several intracellular signaling pathways in hepatocytes including Protein Kinase A (PKA), cAMP regulated guanine nucleotide exchange factors (cAMP-GEFs), and calcium-mediated Protein Kinases. There is considerable overlap and cross-talk between many of these signaling pathways, however, and how these cascades regulate hepatocyte iNOS is not known. We hypothesized that Akt mediates the effect of cAMP on hepatocyte iNOS expression. Hepatocytes cultured with cytokines and dbcAMP increased Akt phosphorylation up to 2h of culture. Akt phosphorylation was inhibited by the PI3K inhibitor LY294002 (10μM), farnyltranferase inhibitor FTI-276, or transfection with a dominant negative Akt. The cyclic AMP-induced suppression of cytokine-stimulated iNOS was partially reversed by LY294002 and FTI-276. LY294002 also increased NFκB nucleus translocation by Western blot analysis in nuclear extracts. Cyclic AMP increased phosphorylation of Raf1 at serine 259 which was blocked by LY294002 and associated with decreased MAPK P44/42 phosphorylation. However, inhibition of MAPK P44/42 signaling with PD98059 failed to suppress cytokine-induced hepatocyte iNOS expression and did not enhance the inhibitory effect of dbcAMP on iNOS production. A constitutively active MAPK P44/42 plasmid had no effect on cytokine-stimulated NO production. These data demonstrate that dbcAMP regulates hepatocyte iNOS expression through an Akt-mediated signaling mechanism that is independent of MAPK P44/42.

BACKGROUND

The time course and mechanisms of altered mechanoenergetics and depressed cross-bridge cycling in hypertrophied and failing myocardium are uncertain.

RESULTS

We studied mechanoenergetics in Dahl salt-sensitive (DS) rats fed high-salt diet (HS) for 6 (HS-6) and 12 (HS-12) weeks to produce compensated hypertrophy and failure. The slope of the end-systolic pressure-volume relation (E'max) was similar in HS-6 and low-salt controls (LS-6), but reduced in HS-12 compared with controls (LS-12). Efficiency [1/slope of oxygen consumption (&f1;O2)-pressure-volume area (PVA) relation] was similar in HS-6 and LS-6 but higher in HS-12 versus LS-12 (59+/-16% versus 44+/-7%, P<0.05). Economy [1/slope of the force-time integral (FTI)-&f1;O2 relation] was similar in HS-6 and LS-6 but higher in HS-12 versus LS-12 (218+/-123 versus 74+/-39x10(3) g. s. mL O2-1. g; P<0.05). Compared with controls, myofibrillar ATPase activity was reduced by 24% in HS-6 and 44% in HS-12. V3 Isomyosin was increased in HS-6 (40+/-12% versus 9+/-8%; P<0.05) and further increased in HS-12 (76+/-10% versus 22+/-18%; P<0.05). Hypothyroid LS-12 rats had 100% V3 isomyosin, yet efficiency, economy, and ATPase values were intermediate between LS-12 and HS-12. HS-12 rats demonstrated increased troponin T3 isoform (17+/-2 versus 23+/-2%, P<0.05). There were no changes in troponin I or tropomyosin isoforms. However, the proportion of phosphorylated troponin T was reduced in HS-12 versus LS-12 hearts (P<.001).

CONCLUSIONS

In DS rats, the transition to failure is associated with depressed E'max and increased efficiency and economy. These findings are linked to myofibrillar ATPase activity and suggest that mechanisms other than isomyosin switching are important determinants of ventricular energetics. A troponin T isoform switch is one potential mechanism.

Protein farnesyltransferase inhibitors (FTIs) have shown clinical responses in hematologic malignancies, but the mechanisms are unclear. To better understand potential mechanisms of action, we have studied effects of the FTI tipifarnib on inflammatory responses in vitro and in vivo. In a human leukemia cell line THP-1, tipifarnib inhibited lipopolysaccharide (LPS)-induced transcription of chemokines [monocyte chemotactic protein (MCP)-1 and MCP-2], cytokines [interleukin (IL)-1beta, IL-6, and interferon (IFN)beta], signaling molecules (MyD88 and STAT-1), proteases [matrix metalloproteinase (MMP-9)], and receptors (urokinase receptor). Tipifarnib also inhibited LPS-induced secretion of MMP-9, IL-6, MCP-1, and IL-1beta in THP-1 cells. In primary human peripheral blood mononuclear cells, dose-dependent inhibition of LPS-induced tumor necrosis factor (TNF)-alpha, IL-6, MCP-1, and IL-1beta by tipifarnib was observed with no evidence of cytotoxicity. Similar results were obtained in vivo in a murine model of LPS-induced inflammation, where pretreatment with tipifarnib resulted in significant inhibition of TNF-alpha, IL-6, MCP-1, IL-1beta, and MIP-1alpha production. Tipifarnib had no effect in vitro or in vivo on LPS-induced IL-8. Studies in THP-1 cells to address potential mechanism(s) showed that tipifarnib partially inhibited LPS-induced p38 phosphorylation. Tipifarnib significantly inhibited inhibitory subunit of nuclear factor-kappaB (NF-kappaB) (IkappaB)-alpha degradation and p65 nuclear translocation induced by LPS, but not by tumor necrosis factor-alpha, IL-1alpha, or toll-like receptor (TLR)2 ligand, suggesting that the target for inhibition of NF-kappaB activation was exclusive to the LPS/TLR4 signal pathway. The extent of IkappaB-alpha degradation inhibition did not correlate with inhibition of Ras farnesylation, indicating that Ras was not the target for the observed anti-inflammatory activity of tipifarnib. Our findings differ from those for other FTIs, which may have relevance for their dissimilar activity in specific tumor repertoires.

In breast cancer, there is an increasing recognition of the pivotal role played by the epidermal growth factor receptor (EGFR) and HER2 together with the various downstream signal transduction pathways, in particular the Ras/Raf/Mek/erk1/2 pathway that regulates cell proliferation together with the phosphatidylinositol-3-OH kinase (PI3K)/Akt/mTOR pathway that is implicated in cell survival. While monoclonal antibodies and small molecule tyrosine kinase inhibitors targeted against EGFR/HER2 are now being used for breast cancer therapy, there is considerable interest in also targeting the critical downstream pathways that cells may remain dependent upon. Activation of these downstream pathways in breast cancer may be associated with resistance to either conventional endocrine or cytotoxic therapies or, indeed, lack of response to EGFR/HER2-targeted approaches. Farnesyltransferase inhibitors (FTIs) were initially developed to target Ras activation, although their mechanism of action may be more nonspecific. Trials in breast cancer have been completed with FTIs alone or in combination with endocrine or cytotoxic therapy. Activation of the PI3K/Akt pathway has also been associated with resistance to either tamoxifen or estrogen deprivation, and preclinical studies have shown that the mTOR antagonists can restore endocrine sensitivity in breast cancer cells. Randomized phase II/III trials of aromatase inhibitors combined with mTOR antagonists are in progress and have been powered to detect whether combined therapy can significantly prolong time to disease progression compared to endocrine therapy alone. Finally, preclinical experiments are now investigating whether downstream agents should be combined with upstream EGFR/HER2 therapies to produce maximal blockade of vertical signal transduction pathways. Subsequent trials will be needed to see whether combinations of novel STIs are well tolerated and how they may further enhance clinical benefit in breast cancer.

Interferon alpha (IFNalpha) induces an EGF-Ras->>Raf-1->>Erk dependent survival pathway counteracting apoptosis induced by the cytokine. In this paper we have evaluated the effects of the combination between farnesyl-transferase inhibitor (FTI) R115777 and IFNalpha on the growth inhibition and apoptosis of cancer cells. Simultaneous exposure to R115777 and IFNalpha produced synergistic both antiproliferative and proapoptotic effects. In these experimental conditions, IFNalpha and R115777 completely antagonized the increased activity of both Ras and Erk-1/2 induced by IFNalpha and strongly reduced Akt activity. Furthermore, treatment with R115777 in combination with IFNalpha regimen induced tumor growth delay on established KB cell xenografts in nude mice, while the single agents were almost inactive. R115777 was again able to antagonize the Ras-dependent survival pathway induced by IFNalpha also in vivo. Raf-1, one of the downstream targets of Ras, has been reported to activate bcl-2 through displacement and/or phosphorylation of Bad. We have found that IFNalpha induced mitochondrial localization of Raf-1 that was antagonized by R115777. Moreover, IFNalpha increased Raf-1/bcl-2 immuno-conjugate formation and intracellular co-localization and enhanced phosphorylation of Bad at Ser 112 and again R115777 counteracted all these effects. Moreover, the use of plasmids encoding for dominant negative or dominant positive Raf-1 antagonized and potentiated, respectively, the co-immunoprecipitation between Raf-1 and bcl-2. In conclusion, FTI R115777 strongly potentiates the antitumor activity of IFNalpha both in vitro and in vivo through the inhibition of different survival pathways that are dependent from isoprenylation of intracellular proteins such as ras.

Mutations in the Kras2 gene are seen in both human and mouse lung adenocarcinomas. The protein product (p21ras) encoded by the Kras2 gene must be post-translationally modified at a terminal CAAX motif in order to be biologically active. In this study, we systematically investigated the chemopreventive efficacy of two different farnesyltransferase inhibitors (FTIs): one is a peptidomimetic (FTI-276) and the other is an imidazole (L778-123). Both FTIs are designed to inhibit the post-translational modification of p21ras proteins with a terminal CAAX motif. In a complete chemoprevention study, where the inhibitor was administered before carcinogen was given, and throughout the study, FTI-276 treatment significantly reduced both the tumor multiplicity by 41.7% (P<0.005), and the total tumor volume by 79.4% (P<0.0001). In the late treatment study, where mice were treated with an inhibitor 12 to 20 weeks after carcinogen administration, FTI-276 treatment resulted in a 60% reduction in tumor multiplicity and 58% reduction in tumor volume. Next, we examined the chemopreventive efficacy of a new FTI, L-778,123, on lung tumor development in A/J mice and transgenic mice with a dominant-negative p53 mutation and/or heterozygous deletion of Ink4a/Arf. Treatment of mice with L-778,123 for a period of 10 weeks from 20 weeks to 30 weeks post carcinogen initiation resulted in an approximately 50% decrease in tumor multiplicity in wild-type mice and mice with a dominant-negative p53 mutation and/or heterozygous deletion of the Ink4a/Arf tumor suppressor genes. Interestingly, tumor volume was decreased approximately 50% in wild-type mice and in mice with an Ink4a/Arf heterozygous deletion, while tumor volume was decreased approximately 75% in animals with a dominant-negative p53 and in mice with both a p53 mutation and heterozygous deletion of Ink4a/Arf. This result suggests that FTI exhibited a significantly (P<0.05) more efficacious chemopreventive effect in animals with alterations of p53 and Ink4a/Arf as contrasted with wild-type mice. Thus, FTIs are potent lung chemopreventive agents in both A/J mice and transgenic mice harboring a dominant-negative p53 and heterozygous deletion of Ink4a/Arf. In fact, L-778,123 is more effective in inhibiting primary lung progression in mice with a p53 mutation and/or an Ink4a/Arf deletion than in wild-type animals.

Ras gene mutations occur in 30% to 40% of patients with multiple myeloma (MM), and farnesylation is the first and most important step in the posttranslational modification of Ras proteins. R115777 is a newly synthesized potent farnesyl transferase inhibitor (FTI) and has recently demonstrated significant antitumor activities in vitro and in vivo. Therefore, we examined the effect of R115777 on the growth of fresh and cloned myeloma cells in vitro. R115777 inhibited the growth of fresh and cloned myeloma cells dose dependently, and effects were not dependent on the status of N-Ras mutation in fresh myeloma cells. Flow cytometric analysis using annexin V and 7-aminoactinomycin D (7AAD) showed that R115777 induced apoptosis of 2 of 3 myeloma cell lines at a concentration of 1.0 x 10(-8) M. R115777 appears to be a potent inducer of apoptosis, and its effects depend on the status of Ras mutation in cloned myeloma cells but not on the status of N-Ras mutation in fresh myeloma cells. This is the first report that demonstrates the relationship between the N-Ras mutation in fresh myeloma cells and the effect of R115777. R115777 might have some benefit in the treatment of myeloma patients.

The concentration of thyroxine-binding globulin (TBG) in the serum can now be measured by direct assays that are simple and inexpensive. Comparison of a direct measurement of TBG concentration with a widely used indirect method (Thyopac-3) showed that the indirect method was inaccurate when TBG concentrations were high. This will result in an increase in the derived free thyroxine index (FTI), so that euthyroid patients with a raised TBG concentration may be at risk of being labelled thyrotoxic. Correction of serum total thyroxine (T4) concentration according to the actual TBG concentration (T4:TBG ratio) provided a better correlation with thyroid state than FTI.

Five patients presented with symptoms of Graves' disease and a marked decrease in their thyroxine-binding globulin (TBG) capacity. While thyrotoxic, mean values +/- SD for the 5 patients were: total thyroxine (TT4) 8.8+/-2.0 mug/100 ml (normal range 4.4-9.3); TBG capacity 6.1+/-1.1 mug T4/100 ml (normal range 16-24); free thyroxine index (FTI) 25.3+/-8.9 (normal range 3.6-9.3); and total triiodo-thyronine (TT3) 244+/-56 ng/100 ml (normal range 80-160). When euthyroid, both TT4 (2.8+/-0.8 mug/100 ml) and TT3 (68+/-12 ng/100 ml) were below the normal range and FTI (5.8+/-0.6) was normal. All patients were male, and family studies revealed decreased TBG capacity in blood relatives consistent with X-chromosome linked inheritance. All examined relatives relatives of the propositi, whether hemizygous or heterozygous, were euthyroid. Over the same period of time 7 additional patients (excluding family members of propositi) were found to be euthyroid but had decreased TBG capacity. The occurrence of thyrotoxicosis in 5 out of 12 patients with inherited TBG deficiency suggests an association rather than a coincidental finding, although initial tests were performed because of suspected thyroid dysfunction. The incidence of thyrotoxicosis in patients with inherited TBG deficiency is also high on the basis of the reported prevalence of the latter genetic abnormality. This study stresses the importance of determining TT3 and FTI on patients who are clinically thyrotoxic but have normal TT4.

Kinetochore (KT) localization of mitotic checkpoint proteins is essential for their function during mitosis. hSpindly KT localization is dependent on the RZZ complex and hSpindly recruits the dynein-dynactin complex to KTs during mitosis, but the mechanism of hSpindly KT recruitment is unknown. Through domain-mapping studies we characterized the KT localization domain of hSpindly and discovered it undergoes farnesylation at the C-terminal cysteine residue. The N-terminal 293 residues of hSpindly are dispensable for its KT localization. Inhibition of farnesylation using a farnesyl transferase inhibitor (FTI) abrogated hSpindly KT localization without affecting RZZ complex, CENP-E, and CENP-F KT localization. We showed that hSpindly is farnesylated in vivo and farnesylation is essential for its interaction with the RZZ complex and hence KT localization. FTI treatment and hSpindly knockdown displayed the same mitotic phenotypes, indicating that hSpindly is a key FTI target in mitosis. Our data show a novel role of lipidation in targeting a checkpoint protein to KTs through protein-protein interaction.

OBJECTIVE

While tamoxifen has been shown to alter concentration of many hormones and their binding globulins, there have been conflicting results regarding its effects on thyroid function tests. We sought to clarify these effects by studying subjects in a controlled clinical trial.

METHODS

We evaluated a subset of postmenopausal women who had participated in a longitudinal, double-blind, randomized, placebo-controlled toxicity study of tamoxifen 10 mg orally, twice daily. There were 14 subjects in both the tamoxifen and placebo groups. Measurement of thyroid-binding globulin (TBG), thyroxine uptake (T-Uptake), thyroxine (T4), and thyroid-stimulating hormone (TSH), and an indirect estimate of the free T4 index (FTI), were made for each subject before and after 3 months of treatment.

RESULTS

For T-Uptake, T4, and TBG, there were significant increases in the mean change from baseline to 3 months in the tamoxifen group compared with the placebo group (P = .02, .0001, and .003, respectively), while there were no significant changes in the measured TSH and in the calculated FTI.

CONCLUSIONS

We conclude that tamoxifen therapy in postmenopausal women results in increased TBG, with secondary increases in measured T-Uptake and T4 following. However, TSH and FTI levels are unchanged, and treated women remain eumetabolic.

OBJECTIVE

To establish the frequency with which anxiolytic and sedative drugs result in fatal poisonings and to examine longitudinal changes in poisoning deaths.

METHODS

The number of fatal poisonings between 1983 and 1999 in England, Scotland and Wales due to a single anxiolytic or sedative drug was obtained from the Department of Health in the UK. This was divided by the number of prescriptions for these drugs in England and Scotland to derive a fatal toxicity index (FTI) of deaths per million prescriptions.

RESULTS

Chloral hydrate, clomethiazole, barbiturates, and related sedatives had much higher FTIs than benzodiazepines, buspirone, zolpidem and zopiclone. There has been a substantial reduction in the annual number of deaths from sedative drug poisoning between 1983 and 1999. This has been due to a sustained reduction in prescriptions for high toxicity drugs and more recently a major reduction in temazepam deaths that coincided with the withdrawal of gelatin capsule formulations.

CONCLUSIONS

Deaths would be expected to be further reduced if there were reduced prescriptions of high toxicity drugs--and the continuing need for short-acting barbiturates, clomethiazole and chloral hydrate should be questioned.

Tests of thyroid function and pathology were carried out on 133 patients before they were treated with lithium (Li+). Of the 12 patients who subsequently became hypothyroid during treatment with lithium 9 had, before the commencement of treatment, thyroid autoantibodies and/or an exaggerated thyroid stimulating hormone (TSH) response to thyrotropin releasing hormone (TRH), whereas 3 patients had neither of these indicators. Lithium administration was accompanied by a rise in thyroid antibody titre in 20 patients but a fall in only 5, a statistically significant difference. Evidence that it may be an immunostimulant is discussed. Li+-induced thyroid failure cannot be accurately predicted, and may occur suddenly. The best minimum safeguard, therefore, is serial thyroxine (T4) (or free T4) estimation, supplemented if equivocal by a free thyroxine index (FTI), a basal TSH and, if doubt remains, by a TRH test.

Defective antitumor immune responses are frequent consequences of defects in the expression of major histocompatibility complex (MHC) class I and costimulatory molecules. We demonstrated that statins, inhibitors of HMGCoA reductase, enhance mIFN-gamma induced expression of MHC class I antigens on murine B16F10 melanoma. GGTI-298, a geranylgeranyl transferase I inhibitor, but not FTI-277, a farnesyl transferase inhibitor, mimics this effect of statins. This effect is related to peptide transporter protein TAP1 up-regulation. Simultaneously, GGTI-298 induces the expression of CD80 and CD86 costimulatory molecules. C3 exoenzyme, which selectively inactivates Rho proteins, phenocopies the effects of GGTI-298, indicating a role for Rho proteins in these events. Furthermore, the treatment of B16F10 cells with GGTI-298 or C3 exoenzyme associated with mIFN-gamma induces in vivo tumor growth slowing down in immunocompetent but not in nu/nu syngeneic mice. Both in vivo injections and in vitro restimulation of splenocytes with GGTI-298- and mIFN-gamma-treated B16F10 cells induces an enhancement of specific CD8 T lymphocytes labeled by TRP-2/H-2K(b) tetramers. Finally, these effects are not limited to mouse models since they were also reproduced in two human melanoma cell lines. These observations indicate that protein geranylgeranylation as well as Rho protein are critical for costimulatory and IFN-gamma-dependent MHC class I molecule expression in melanoma.

In Finnish data from 1995-2000, 1006 fatal poisonings due to alcohol (ethanol), a single drug or both were statistically analysed in retrospect to evaluate the interaction between alcohol and drugs. In 53% of these cases, low concentrations of some common benzodiazepines were present. The median postmortem blood alcohol concentration (BAC) was 3.3 percent per thousand (w/w) in the 615 alcohol poisonings, but significantly lower, ranging from 1.3 to 1.7 percent per thousand, when promazine, doxepin, amitriptyline or propoxyphene were found together with alcohol. When levomepromazine, temazepam or zopiclone were present, the median BAC was also significantly lower, 2.5-2.7 percent per thousand. Citalopram and diltiazem did not exhibit a significant effect. The median BAC was significantly lower in cases with high concentrations than in those with low concentrations of a drug (excluding citalopram), suggesting a positive concentration-effect relationship. Fatal toxicity indices (FTIs) were calculated by relating the number of deaths caused by a drug to the corresponding sales figures. Promazine had an extremely high FTI, followed by levomepromazine, propoxyphene, doxepin and amitriptyline. The other drugs had relatively low FTIs. The results reflect not only the acute toxicity of a given drug-alcohol combination but also the manners of use and abuse of these drugs.

The E-cadherin/catenin cell adhesion system is often down-regulated in epithelial tumors. This is thought to play an important role in cancer invasion and metastasis, and restoration of this system may suppress metastatic spread of cancer. In this study, the effects of a Ras farnesylation inhibitor (FTI-277) on E-cadherin-mediated cell-cell adhesion and metastatic potential were examined. In cell aggregation assays, FTI-277 stimulated aggregation of colon, liver and breast cancer cells. In vitro cultures of cancer cells showed that FTI-277 induced strong cell-cell contact. Immunoblotting analysis showed that FTI-277 increased E-cadherin/catenin (alpha, beta and gamma) expression and strongly stabilized E-cadherin/catenin with the actin cytoskeleton. Northern blotting studies indicated that the observed increase in the E-cadherin/catenin protein content was due to increased expression of their genes. After inoculation of the spleens of mice with severe combined immunodeficiency (SCID) with cancer cells, FTI-277 treatment for 3 weeks markedly reduced splenic primary tumor growth and the rate of liver metastasis compared with control counterparts. Our data demonstrate that FTI-277 can activate functioning of the E-cadherin-mediated cell adhesion system, which is associated with suppression of cancer cell metastasis. Therefore, selective inhibition of Ras activation may be useful for preventing cancer metastasis.

Mouse mammary tumor virus-transforming growth factor alpha (MMTV-TGF alpha) and MMTV-TGF alpha/neu transgenic mice develop mammary tumors after a long latency and therefore provide useful model systems for breast cancer with its recognized activation of receptor tyrosine kinase signaling. We used these mice to study the antitumor effect of L-744,832 (FTI), a potent and selective inhibitor of farnesyl-protein transferase, and hence of Ras function. A total of 55 mice were assigned randomly to treatment with FTI or vehicle, and one-half of the mice were crossed over after initial treatment to the opposite group. L-744,832 induced reversible regression of mammary tumors that was paralleled by a decrease in serum levels of TGF alpha secreted by the tumor cells. There was no difference in response to treatment with FTI between MMTV-TGF alpha mice, in which tumorigenesis was accelerated by multiparity or the chemical carcinogen 7,12-dimethylbenzanthracene, and MMTV-TGF alpha/neu mice. The tumor histological type had no impact on FTI sensitivity. For mechanistic analyses, tumor excision biopsies were obtained from 12 mice before and after treatment with L-744,832. In these samples, tumor regression was paralleled biochemically by inhibition of mitogen-activated protein kinase activity and biologically by an increase in G1-phase and decrease in S-phase fractions, as well as induction of apoptosis. These results suggest that the potential clinical use of FTI could be expanded to include cancers harboring activated receptor tyrosine kinases as well as those containing activated Ras.

BACKGROUND

Female abdominal obesity is associated with hyperandrogenemia (HA), but few studies have addressed the possible association between HA and metabolic syndrome (MetS) among obese women. Some studies indicate that insulin resistance may cause HA through different mechanisms. On the other hand, a bidirectional relationship between HA and insulin resistance has been suggested. Thus, we aimed to investigate if morbidly obese women with HA had higher odds of MetS and its components than those without HA (controls), independent of polycystic ovarian syndrome (PCOS) status.

METHODS

This cross-sectional study comprised 1900 consecutive treatment seeking morbidly obese women <50 years. Free testosterone index (FTI) >0.6 defined HA. Women with previously diagnosed PCOS and those with oligo- / anovulation combined with clinical or biochemical hyperandrogenism were defined as having PCOS. Multiadjusted associations between HA and MetS were assessed by logistic regression analysis.

RESULTS

Out of 1900 morbidly obese women, 1089 (57 %), 846 (45 %) and 312 (16 %) had MetS, HA and PCOS, respectively. Compared with controls (without HA), women with HA were younger (34 [1] years vs. 39 [2], p < 0.001) had a higher prevalence of MetS (62 % vs. 53 %, p < 0.001), type 2 diabetes (18 % vs. 15 %, p = 0.045), low HDL-cholesterol (65 % vs. 48 %, p < 0.001) and hypertriglyceridemia (48 % vs. 41 %, p = 0.004), but a lower prevalence of raised blood pressure (53 % vs. 59 %, p = 0.014). Multivariable analyses showed that HA was associated with increased odds of MetS (OR 1.61 [95 % CI 1.27, 2.02]), dysglycemia (1.65 [1.28, 2.11]), low HDL-cholesterol (1.58 [1.27, 1.97]), and hypertriglyceridemia (1.43 [1.15, 1.79]). After stratification for the presence of PCOS, the results remained largely unchanged in women without PCOS; MetS (1.52 [1.18, 1.96), dysglycemia (1.71 [1.30, 2.25]), low HDL-cholesterol (1.55 [1.22, 1.98]) and hypertriglyceridemia (1.36 [1.06, 1.74]).

CONCLUSIONS

Morbidly obese women with HA had an approximately 1.5-fold increased odds of having MetS even in the absence of PCOS. Randomized controlled clinical trials, including therapeutic strategies to lower free testosterone levels, are however necessary to explore any cause-and-effect relationship.

OBJECTIVE

After pulmonary vein isolation (PVI), dormant conduction (DC) is present in at least one vein in a substantial number of patients. The present study seeks to determine whether there is a relationship between poor contact forces (CF) and the presence of DC after PVI.

RESULTS

This prospective, operator-blinded, non-randomized dual-centre trial enrolled 34 consecutive patients with paroxysmal atrial fibrillation who were candidates for PVI. Radiofrequency (RF) energy was delivered by using an irrigated-tip force-sensing ablation catheter (Tacticath, St Jude Medical) at pre-defined target power. The operators were blinded to the CF data at all times. A total of 1476 RF applications were delivered in 743 pre-defined PV segments. For each application, the precise location of the catheter was registered and the following data were extracted from the Tacisys unit: application duration, minimum contact force, maximum contact force, average contact force (CF), and force-time integral (FTI). Sixty minutes after PVI, spontaneous early recovery (ER) of the left atrium (LA) to PV conduction was evaluated. In the absence of ER, the presence of a DC was evaluated by using intravenous adenosine (ATP). In the 34 patients recruited (23 males; mean age: 62 ± 9 years), all PVs were successfully isolated. At the end of the 60 min waiting period, 22 patients demonstrated at least one spontaneous ER or DC under ATP. The mean CF and FTI per PV segment differed significantly among the different veins but the sites of ER and DC were evenly distributed. However, both the minimum, the first and the mean CF and FTI per PV segment were significantly lower in the PV segments presenting either ER or DC as compared with those without ER or DC (mean CF: 4.9 ± 4.8 vs. 12.2 ± 1.65 g and mean FTI: 297 ± 291 vs. 860 ± 81 g s, P < 0.001 for both). Using multivariate analysis, both the mean CF and the FTI per lesion remained significantly associated with the risk of ER or DC. Moreover, a CF < 5 g per PV segment predicted ER+ and DC+ with a sensitivity of 71% and specificity of 82%. In contrast, ER and DC were very unlikely if RF application was performed with a mean CF>> 10 g (negative predictive value: 98.7%).

CONCLUSIONS

Both a low CF and a low FTI are associated with the ER of the PVI and DC after PVI.

Aromatase inhibitors (AIs), the adjuvant hormonal treatment of choice for postmenopausal estrogen receptor-positive breast cancer, are associated with an increased risk of musculoskeletal symptoms. The underlying cause of the symptoms is often attributed to estrogen depletion, yet all women treated with AIs have low estrogen levels and only a subset develop symptoms. Concentrations of circulating androgens may be mediating factors contributing to these side effects. The purpose of this study was to examine changes in androgen concentrations among women initiating AI therapy and to determine if concentrations are associated with musculoskeletal symptoms. Data were analyzed from a cohort study of 74 breast cancer patients for whom AI therapy was planned. Questionnaire data on symptoms were collected and blood was drawn prior to AI therapy (baseline) and then again at 3 and 6 months after baseline. Blood was assayed for testosterone, androstenedione, dehydroepiandrosterone-sulfate (DHEAS), and sex hormone-binding globulin (SHBG). Free testosterone index (FTI) values were calculated using testosterone and SHBG measurements. The results showed that concentrations of all of the androgens increased over the study period, with statistically significant differences from baseline concentrations observed for the FTI at 3 and 6 months and for DHEAS at 6 months. Additionally, breast cancer patients with new onset or worsening of pain over the study period had a significantly smaller change in mean DHEAS concentration from baseline to 3 months (P = 0.04) and a marginally significant smaller change in mean DHEAS concentration from baseline to 6 months (P = 0.1) compared to those who reported no pain at all time points or no worsening of pain across the study period. Changes in testosterone, androstenedione, and the FTI were not associated with the onset or worsening of pain during the study period. Findings from this study suggest that higher DHEAS concentrations are associated with less AI-associated pain and should be further investigated.

The discovery of genetic, genomic and clinical biomarkers have revolutionized the treatment option in the form of personalized medicine which allows to accurately predict a person's susceptibility/progression of disease, the patient's response to therapy, and maximize the therapeutic outcome in terms of low/no toxicity for a particular patient. Recently, the U.S. Food and Drug Administration has realized the contribution of pharmacogenomics in better healthcare and advocated the consideration of pharmacogenomic principles in making safer and more effective drug. Many anticancer drugs show reduced or no response in cancer patients with tumor specific gene mutations such as B-Raf and K-Ras. The high incidence of K-Ras mutation has been reported in pancreatic, colon, and lung carcinomas. The identification of K-Ras as a clinical biomarker and potential therapeutic target has attracted the scientific community to develop effective and precise anticancer drug. Inhibitors which block farnesylation of Ras have been developed or under clinical trial studies. Tipifarnib, approved by USFDA for the treatment of elderly acute leukemia is a Ras pathway inhibitor. Some peptidomimetics and bi-substrate inhibitors like FTI 276, FTI 277, B956, B1086, L731, L735, L739, L750, BMS-214662, L778123, and L778123 are under clinical trials. Recently mutant K-Ras has been considered as potential biomarker and target for precise cancer therapy. This review focuses primarily on the Ras/Raf/MEK/ERK signaling pathway including K-Ras mutation as therapeutic target, inhibitors and their structure activity relationships (SARs) for the design and development of anticancer agents.

OBJECTIVE

To perform a meta-analysis of published data on the prevalence and risk of malignancy of focal thyroid incidental uptake (FTIs) detected by Fluorine-18-Fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) or PET/CT.

METHODS

A comprehensive literature search of studies published up to and including December 2012 was performed. Pooled prevalence and malignancy risk of FTIs were calculated, including a sub-analysis for the geographic areas of origin of the studies.

RESULTS

34 studies including 215,057 patients were selected. Pooled prevalence of FTIs was 1.92% (95% confidence interval [95%CI]: 1.87-1.99%). Overall, 1522 FTIs underwent histopathology evaluation. Pooled risk of malignancy was 36.2% (95%CI: 33.8-38.6%), without significant differences among various geographic areas.

CONCLUSIONS

FTIs are observed in about 2% of 18F-FDG-PET or PET/CT scans and carry a significant risk of malignancy. Therefore, further investigation is warranted whenever FTIs are detected by 18F-FDG-PET or PET/CT.