In vitro activities of DA-7157 and DA-7218 against Mycobacterium tuberculosis and Nocardia brasiliensis

The in vitro activities of DA-7157, a novel oxazolidinone, against clinical isolates of Nocardia brasiliensis and Mycobacterium tuberculosis were determined. Equal MIC(50)s and MIC(90)s (0.25 and 0.5 microg/ml, respectively) were found for susceptible and multidrug-resistant isolates of M. tuberculosis. The N. brasiliensis isolates showed an MIC(90) of 1 microg/ml and an MIC(50) of 1 microg/ml. The DA-7157 prodrug, DA-7218, exhibited similar MICs for M. tuberculosis but fivefold-higher MICs for N. brasiliensis.

Insulin signaling diverges into Akt-dependent and -independent signals to regulate the recruitment/docking and the fusion of GLUT4 vesicles to the plasma membrane

Insulin modulates glucose disposal in muscle and adipose tissue by regulating the cellular redistribution of the GLUT4 glucose transporter. Protein kinase Akt/PKB is a central mediator of insulin-regulated translocation of GLUT4; however, the GLUT4 trafficking step(s) regulated by Akt is not known. Here, we use acute pharmacological Akt inhibition to show that Akt is required for insulin-stimulated exocytosis of GLUT4 to the plasma membrane. Our data also suggest that the AS160 Rab GAP is not the only Akt target required for insulin-stimulated GLUT4 translocation. Using a total internal reflection microscopy assay, we show that Akt activity is specifically required for an insulin-mediated prefusion step involving the recruitment and/or docking of GLUT4 vesicles to within 250 nm of the plasma membrane. Moreover, the insulin-stimulated fusion of GLUT4 vesicles with the plasma membrane can occur independently of Akt activity, although based on inhibition by wortmannin, it is dependent on phosphatidylinositol 3' kinase activity. Hence, to achieve full redistribution of GLUT4 into the plasma membrane, insulin signaling bifurcates to independently regulate both fusion and a prefusion step(s).

Vibrational spectra of germanium-carbon clusters in solid Ar: identification of the nu4(sigma(u)) mode of linear GeC5Ge

The linear GeC(5)Ge cluster has been detected in Fourier transform infrared spectra observed when the products from the dual laser evaporation of carbon and germanium rods were trapped in solid Ar at approximately 10 K. Comparison of (13)C isotopic shift measurements with the predictions of density functional theory calculations at the B3LYP/cc-pVDZ level confirms the identification of the nu(4)(sigma(u)) mode of GeC(5)Ge at 2158.0 cm(-1).

Selection of induction chemotherapy (CT) in esophageal and gastroesophageal junction cancer by positron emission tomography (PET)

14041

Background: Preoperative CT improves survival in esophageal cancer. 50% of patients (pts) do not respond to cisplatin+5-FU (C+F). The reduction of fluorodeoxyglucose uptake after 14 days (d) of CT predicts clinical response (rsp). Our objective was to measure the rsp (rsp) rate after CT adjusted according to PET rsp. Methods: Eligible pts were ≥ stage II esophageal cancer and able to tolerate CT. By adjusting CT according to PET rsp, we expected an increase of rsp rate by 25%. Taking into account a confidence level of 90%, an error β of 20% and a minimal error of 15% (even with such a high error rate the data will exceed the standard results), we calculated a sample size of 23 pts. All underwent esophagoscopy, computed tomography and PET scan prior to C (100mg/m2 d1) +5-FU (1,000mg/m2 d1–5). If PET rsp after first cycle (uptake decreased ≥ 35%), we continued up to third C+F cycle, then if endoscopy rsp: C+F + concurrent radiation only if stage II or III. If no endoscopy rsp, surgery only if stage II or III. On the other hand, if the pts had no rsp in PET after first C+F cycle they continued with 2 cycles of docetaxel (35mg/m2 d 1 & 8) and irinotecan (50mg/m2 d 1 & 8) (D+I) every 21 d and then if endoscopy rsp: radiation + docetaxel only if stage II or III. If no endoscopy rsp, surgery. Results: Since 2/04, 23 pts have been enrolled. Location: 2 cervical, 4 upper thoracic, 7 mid-thoracic, 10 GE junction. PET stage: 7 IIA, 6 IIB, 2 III, 2 IVA, 6 IVB. Up-staging with PET in 6 pts, down-staging in 4 pts. Histology: 10 Adenocarcinoma, 13 squamous carcinoma. Improved swallowing function: from a total of 12 PET responders, 9 had a clinical rsp after C+F, 3 did not. From 11 PET non-responders, 7 had a clinical rsp after D+I, 4 did not. Global clinical rsp = 16/23 (70%). Endoscopy rsp (frequent inaccuracy by overstaging): from a total of 12 PET responders, 6 had a clinical rsp after C+F, 6 did not. From 11 PET non-responders, 7 had a clinical rsp after D+I, 4 did not. Global clinical rsp = 13/23 (57%). Conclusion: Our results suggest that it is possible to significantly increase the percentage of pts who respond to induction CT adjusted according to PET in esophagogastric cancer before concurrent chemoradiotherapy or esophagectomy, or both.

No significant financial relationships to disclose.

Incidence of deep venous thrombosis associated with central venous catheters (DVT-CVC) in cancer patients: A multicenter study

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Background: The reported incidence of DVT-CVC is extremely variable (0.3–28.3% for symptomatic thrombosis and 27–66% for asymptomatic thrombosis). Data in regarding new catheter materials and insertion techniques are very limited. Likewise, the use of antithrombotic prophylaxis in cancer patients with a CVC remains debatable. Methods: A prospective epidemiologic study was performed, which included adult patients with active cancer and no history of venous thromboembolism, in whom a long term CVC was inserted. Patients were followed-up for 90 days and a bilateral upper extremity Doppler-ultrasound was performed on days 45±5 and 90±5. Likewise, basal blood samples were taken and have been analyzed for hypercoagulability markers and prothrombotic factors. Results: Inclusion period lasted from July 2004 until May 2005. 141 patients have completed the follow up, with a mean age of 52.1±14.3 years (range 21–87). The cumulative incidence of DVT-CVC was 14.2% (20/141): 6.4% were symptomatic (9/141) and 8.9% were asymptomatic (11/123). All thrombotic events, excluding 4 cases, occurred before day 45. Neither age, gender, type of tumor (solid or haematological cancer), tumor stage, type of CVC (Port or tunnelled), number of lumens, side of insertion, platelet count or use of antithrombotic prophylaxis were significantly associated with the incidence of DVT-CVC, although only 1/8 patients with DVT-CVC receiving antithrombotic prophylaxis (12.5%) used high risk prophylaxis. Patients with prior central catheters tended to have a greater incidence of DVT-CVC (P=0.10). None of the basal plasma markers analyzed (fibrinogen, D dimer, F VIII, proteine C resistance, prothrombin fragments 1+2, thrombin-antithrombin complex) have been significantly associated with increased risk of DVT-CVC. Conclusions: DVT-CVC is a frequent complication in cancer patients, as with solid tumors so with haematologic malignancies. The incidence of DVT-CVC seems to be specially high the first few weeks following catheter placement. None of the basal plasma markers analyzed in this study have been associated with the incidence of DVT-CVC. New studies must be performed to allow identification of at risk patients who might benefit from antithrombotic prophylaxis.

No significant financial relationships to disclose.

Rac1 modulates sphingosine 1-phosphate-mediated activation of phosphoinositide 3-kinase/Akt signaling pathways in vascular endothelial cells

Sphingosine 1-phosphate (S1P) is a platelet-derived sphingolipid that activates G protein-coupled S1P receptors and initiates a broad range of responses in vascular endothelial cells. The small GTPase Rac1 is implicated in diverse S1P-modulated cellular responses in endothelial cells, yet the molecular mechanisms involved in S1P-mediated Rac1 activation are incompletely understood. We studied the pathways involved in S1P-mediated Rac1 activation in bovine aortic endothelial cells (BAEC) and found that S1P-induced Rac1 activation is impaired following chelation of G protein betagamma subunits by transfection of betaARKct. Treatment with the Src tyrosine kinase inhibitor PP2 completely attenuated S1P-mediated Rac1 activation; however, pretreatment of BAEC with wortmannin, an inhibitor of phosphoinositide (PI) 3-kinase, had no effect on Rac1 activation while completely blocking S1P-induced Akt phosphorylation. We used Rac1-specific small interfering RNA (siRNA) duplexes to "knock down" endogenous Rac1 expression and found that siRNA-mediated Rac1 knockdown significantly impaired basal as well as S1P-induced phosphorylation of protein kinase Akt, as well as several downstream targets of Akt including endothelial nitric-oxide synthase and glycogen synthase kinase 3beta. By contrast, S1P-induced phosphorylation of the mitogen-activated protein kinases ERK1/2 was unperturbed by siRNA-mediated Rac1 knockdown. We found that overexpression of the Rac1 guanine nucleotide exchange factor (GEF) Tiam1 markedly enhanced Rac1 activity, whereas a dominant negative Tiam1 mutant significantly attenuated S1P-mediated Rac1 activation. Taken together, these studies identify G protein betagamma subunits, Src kinase and the GEF Tiam1 as upstream modulators of S1P-mediated Rac1 activation, and establish a central role for Rac1 in S1P-mediated activation of PI 3-kinase/Akt/endothelial nitric-oxide synthase signaling in vascular endothelial cells.

Rapamycin at Six Years Can Exhibit Normal Renal Function Without Proteinuria or Neoplasia After Renal Transplantation. A Single-Center Experience

Currently, long-term experience with Rapamune (RAPA) after renal transplantation is scarce. We present our experience with RAPA in patients who were included in clinical trials. Between 1996 and 1999, 27 renal transplant patients received RAPA alone or in combination with cyclosporine (CyA). We study 15 of them (9 males, 6 females; mean age 36 years) who are currently functioning with a mean follow-up of 6 years (range, 5.2-8 years). The presence of delayed graft function was 40% and acute rejection 26.6%, all of them controlled with steroids. Notably, no patients experienced an acute rejection episode after the first year. Among 15 patients, 12 received steroids, RAPA and CyA; and 3 received steroids, RAPA, azathioprine (AZA) or mycophenolate mofetil (MMF) for immunosuppression. At the end of follow-up, the situation was the opposite: 12 patients received steroids (2.5-5 mg/d) and RAPA associated with or without AZA/MMF, and 3 were maintained with steroids, RAPA and CyA. Renal function was excellent in the entire group: mean SCr 1.1 mg/dL (range, 0.7-1.8) with mean RAPA blood levels (HPLC) of 11 ng/dL (range 8-16). Hyperlipidemia was universal with all patients (100%) receiving statins maintaining acceptable levels of cholesterol (mean 209 +/- 28 mg/dL) and tryglycerides (mean 154 +/- 76 mg/dL). Arterial hypertension present in 12 of 15 (80%) patients was controlled with a mean of 1.5 drugs. Notably, no patient presented with proteinuria, neoplasia, posttransplant diabetes, or cardiovascular events. In conclusion, these single-center results suggest that Rapamune may be useful in the long-run after renal transplantation. The presence of normal renal function and the absence of proteinuria and neoplasia in these renal transplant patients may have important clinical implications.

Once-daily antiretroviral therapy: Spanish Consensus Statement

BACKGROUND

Administration of antiretroviral therapy (ART) once daily is creating extraordinary interest among the members of the scientific community and also among those who receive the therapy. However, in clinical practice, some doubts remain about its use.

OBJECTIVES

This document examines the characteristics and possibilities of treatment administered once daily.

METHODS

Consensus of 248 Spanish experts in the field.

RESULTS

Once-daily dosing is considered an added value which could favour adherence and, therefore, efficacy, as well as the quality of life of certain patients, however, the objective of adequate adherence in the long term is often difficult to achieve regardless of the treatment used. In theory, any patient can receive once-daily therapy, although some patients could particularly benefit from it, e.g. those with unfavourable social or personal circumstances, including drug users, patients whose treatment must be supervised, patients receiving multiple medications, or those who need rescue therapy after multiple treatment failures. At present, it is possible to design once-daily ART using some of the combinations of drugs considered as first-choice in national and international recommendations for antiretroviral therapy, but the options are still limited. The marketing of new drugs with this characteristic could allow us to increase the number and types of patient who can benefit from once-daily regimens, including those patients who need rescue therapy.

CONCLUSIONS

Once-daily ART is a good alternative to regimens administered several times each day when a potent combination of active drugs is available.

[Interactions of caffeine with DNA double helix fragments. Molecular mechanics simulation]

Calculations of the energy of interaction between the caffeine molecule and DNA double helix fragment of four complementary pairs have been performed by the molecular mechanics method. The calculations demonstrate the existence of energy minima corresponding to the caffeine molecule position in both wide and narrow grooves. Each of three proton acceptor atoms of caffeine is able to form hydrogen bond with each of three amino groups of DNA bases. The interactions of caffeine with both hydrogen bonded nucleotide and other nucleotides of the two strands contribute considerably to the total energy. The substantial contribution of interactions of caffeine with other than H-bonded nucleotides results in a rather close packing of atom groups in possible DNA-caffeine complexes. The mechanisms of influence of caffeine on interactions of DNA with other biologically active compounds are discussed.

The role of alterations in arachidonic acid metabolism and nitric oxide homeostasis in rat models of diabetes during early pregnancy

The diabetic pathology induces reproductive abnormalities that enhance spontaneous abortion, congenital anomalies and neonatal morbidity/mortality rates, abnormalities that begin with an altered female gamete. In this review we focus on the damage induced by maternal hyperglycemia during ovulation, early embryo development, implantation and embryo organogenesis in experimental rat models of diabetes. Hyperglycemia can induce cellular damage by enhancing the production of reactive oxygen species (ROS), by altering arachidonic acid metabolism (thus leading to altered production of prostaglandins such us PGE(2)and 15deoxydelta(12-14)PGJ(2), involved in signalling and developmental pathways), and by enhancing the generation of nitric oxide (a mediator of many cell functions including apoptotic cell death). In maternal diabetes all of these abnormalities are present from the oocyte stage, during embryonic implantation, and during embryo organogenesis. The involvement of these alterations in embryo loss and congenital malformations due to diabetes and the cross-talk among these metabolic pathways are discussed. As maternal hyperglycemia induces damage from the oocyte stage and throughout embryo development the data reviewed suggests the need of strict preconceptional metabolic control. The importance of the molecules involved in hyperglycemia-induced damage as future pharmacological targets for intervention is discussed.

15-Deoxy-Δ12,14-prostaglandin J2 and peroxisome proliferator-activated receptor γ (PPARγ) levels in term placental tissues from control and diabetic rats: modulatory effects of a PPARγ agonist on nitridergic and lipid placental metabolism

15-Deoxy-Δ12,14-prostaglandin J2 (15dPGJ2) is a peroxisome proliferator-activated receptor γ (PPARγ) ligand that regulates lipid homeostasis and has anti-inflammatory properties in many cell types. We postulated that 15dPGJ2 may regulate lipid homeostasis and nitric oxide (NO) levels in term placental tissues and that alterations in these pathways may be involved in diabetes-induced placental derangements. In the present study, we observed that, in term placental tissues from streptozotocin-induced diabetic rats, 15dPGJ2 concentrations were decreased (83%) and immunostaining for nitrotyrosine, indicating peroxynitrite-induced damage, was increased. In the presence of 15dPGJ2, concentrations of nitrates/nitrites (an index of NO production) were diminished (40%) in both control and diabetic rats, an effect that seems to be both dependent on and independent of PPARγ activation. Exogenous 15dPGJ2 did not modify lipid mass, but decreased the incorporation of 14C-acetate into triacylglycerol (35%), cholesteryl ester (55%) and phospholipid (32%) in placenta from control rats, an effect that appears to be dependent on PPARγ activation. In contrast, the addition of 15dPGJ2 did not alter de novo lipid synthesis in diabetic rat placenta, which showed decreased levels of PPARγ. We conclude that 15dPGJ2 modulates placental lipid metabolism and NO production. The concentration and function of 15dPGJ2 and concentrations of PPARγ were altered in placentas from diabetic rats, anomalies probably involved in diabetes-induced placental dysfunction.

Small Interfering RNA-mediated Down-regulation of Caveolin-1 Differentially Modulates Signaling Pathways in Endothelial Cells

Caveolin-1 is a scaffolding/regulatory protein that interacts with diverse signaling molecules in endothelial cells. To explore the role of this protein in receptor-modulated signaling pathways, we transfected bovine aortic endothelial cells (BAEC) with small interfering RNA (siRNA) duplexes to down-regulate caveolin-1 expression. Transfection of BAEC with duplex siRNA targeted against caveolin-1 mRNA selectively "knocked-down" the expression of caveolin-1 by approximately 90%, as demonstrated by immunoblot analyses of BAEC lysates. We used discontinuous sucrose gradients to purify caveolin-containing lipid rafts from siRNA-treated endothelial cells. Despite the near-total down-regulation of caveolin-1 expression, the lipid raft targeting of diverse signaling proteins (including the endothelial isoform of nitric-oxide synthase, Src-family tyrosine kinases, Galphaq and the insulin receptor) was unchanged. We explored the consequences of caveolin-1 knockdown on kinase pathways modulated by the agonists sphingosine-1 phosphate (S1P) and vascular endothelial growth factor (VEGF). siRNA-mediated caveolin-1 knockdown enhanced basal as well as S1P- and VEGF-induced phosphorylation of the protein kinase Akt and did not modify the basal or agonist-induced phosphorylation of extracellular signal-regulated kinases 1/2. Caveolin-1 knock-down also significantly enhanced the basal and agonist-induced activity of the small GTPase Rac. We used siRNA to down-regulate Rac expression in BAEC, and we observed that Rac knockdown significantly reduced basal, S1P-, and VEGF-induced Akt phosphorylation, suggesting a role for Rac activation in the caveolin siRNA-mediated increase in Akt phosphorylation. By using siRNA to knockdown caveolin-1 and Rac expression in cultured endothelial cells, we have found that caveolin-1 does not seem to be required for the targeting of signaling molecules to caveolae/lipid rafts and that caveolin-1 differentially modulates specific kinase pathways in endothelial cells.

Influence of peroxisome proliferator-activated receptor activation by its endogenous ligand 15-deoxy 12,14 prostaglandin J2 on nitric oxide production in term placental tissues from diabetic women

Diabetes induces alterations which condition placental remodelling. The levels of nitric oxide (NO) (a modulator of placental invasiveness, differentiation and proliferation) were higher in term placental explants from diabetic patients when compared to controls. Peroxisome proliferator-activated receptor gamma (PPARgamma) activation by its endogenous ligand 15-deoxy Delta(12,14)prostaglandin J(2) (15dPGJ(2)), is a differentiating factor of adipocytes and other cell types, such as trophoblasts. 15dPGJ(2) is also able to down-regulate NO production in different cell types. Our study evaluated the levels of 15dPGJ(2) and PPARgamma and the influence of PPARgamma activation by 15dPGJ(2) on the production of NO, in term placental tissues from control, pre-gestational and gestational diabetic patients. Our results showed that 15dPGJ(2) was present in human term placenta, and that its levels were diminished in gestational (P<0.05) and pre-gestational (P<0.002) diabetic women when compared to controls. Exogenous 15dPGJ(2) addition (2 x 10(-6) mol/l) down-regulated NO production in placenta from control (P<0.001) and pre-gestational diabetic (P<0.01) patients, but failed to do so in gestational diabetic women, whose placental PPARgamma expression was diminished in comparison to controls (P<0.001). As the exogenous activation of PPARgamma prevented NO overproduction in placenta from pre-gestational diabetic women, it may have the potential to improve fetal outcome in this pathology.

In vitro activities of new antimicrobials against Nocardia brasiliensis

The in vitro sensitivities of 30 strains of Nocardia brasiliensis to DA-7867, gatifloxacin, moxifloxacin, and BMS-284756 (garenoxacin) were determined using the broth microdilution method. All N. brasiliensis strains were sensitive to these antimicrobials. The most active drug in vitro was DA-7867, with a MIC at which 90% of the isolates tested were inhibited of 0.03 micro g/ml and a MIC at which 50% of the isolates tested were inhibited of 0.06 micro g/ml.

Plasma erythropoietin levels in the oldest old

Erythropoietin (EPO) regulates erythrocytes production and is synthesized mainly by the kidney. Its production is reduced during chronic renal failure but is not altered by the senescence process in spite of the morphological changes that occur in the kidney. However, there is no information regarding what happens to erythropoietin synthesis during advanced ageing. Thus, we carried out an investigation to determine whether there was any significant difference in plasma erythropoietin between adults, old and very old people.

MATERIAL AND METHODS

We studied 74 healthy volunteers: 22 adults, 30 old, and 22 very old. None of them were smokers or were suffering from any disease that may intefere with hemoglobin (Hb) levels or with EPO production. Hematocrit, Hb, plasma creatinine and plasma erythropoietin were measured, and creatinine clearance was calculated from serum creatinine using two different formulae. Statistical analysis was performed using ANOVA and Bonferroni tests.

RESULTS AND CONCLUSION

Among the three groups we found a significant difference in creatinine clearance (p < 0.001), but not in plasma erythropoietin levels; we conclude that normal senescence does not alter plasma erythropoietin levels, even during advanced ageing.

Comparative efficacy and side effects of the treatment of euthyroid goiter with levo-thyroxine or triiodothyroacetic acid

Euthyroid goiter is usually treated with TSH-inhibitory doses of levo-T(4) (L-T(4)). Because triiodothyroacetic acid (TRIAC) decreases TSH levels, the following study was perfomed: 36 euthyroid goitrous female patients (no cancer or chronic thyroiditis) were randomized to TRIAC (19.6 micro g/kg) (n = 19) or L-T4 (1.7 microg/kg) (n = 17) treatment during 11 months. Goiter volume; lumbar and femoral bone mineral density; serum osteocalcin; deoxypyridinoline; TSH; free T(4); total, high-density lipoprotein, and low-density lipoprotein cholesterol; and triglycerides were measured before and after the study period. Student's t test and chi(2) analysis were performed. TSH values (microunits per milliliter) in the TRIAC and L-T(4) groups were: 1.91 +/- 0.6 (basal) and 0.180 +/- 0.1 (after) and 2.1 +/- 2.5 (basal) and 0.180 +/- 0.3 (after), respectively. Thyroid volume decreased 37.9 +/- 35.4% in the TRIAC patients and 14.5 +/- 39.5% in the L-T(4) group (P = 0.069). Forty-two percent of the goiters with TRIAC reduced more than 50% their initial volume vs. 17.7% with L-T(4) (P = 0.15). With TRIAC, patients experienced fewer side effects. No differences in the changes of bone mineral density, serum deoxypyridinoline, osteocalcin, or the lipid profile were observed between both groups. The present results show that TRIAC is more effective than L-T(4) in the reduction of goiter size, with comparable effects on peripheral parameters.

[Possible configuration of dimers of Gua-Cyt bases. Computation by molecular mechanic models and density functional theory]

The energies of interactions between guanine and cytosine in various mutual positions were calculated by the methods of molecular mechanics with refined atom-atom potential functions and the quantum mechanics theory of density functional. Both methods indicate three types of mutual positions of bases in local energy minima. These types correspond to (1) nearly coplanar base positions with intermolecular hydrogen bond formation (base pairing); (2) arrangements of two bases in nearly parallel planes one above another (base stacking); and (3) nearly perpendicular positions of base planes. According to the calculations, the global energy minimum corresponds to the Watson-Crick base pair with three hydrogen bonds. A specific feature of the pair is a transition from many positions of type (2) to positions of type (1) without any energy barrier. This feature is revealed by both methods. Another special feature of this pair is a deviation, for most of mutual base positions, of the amine group atoms from the ring plane, the deviation being more pronounced for Gua. These features are important for understanding the conformational behavior of DNA fragments and the RNA structure.