Reactive Oxygen Species Contribute to the Bactericidal Effects of the Fluoroquinolone Moxifloxacin in Streptococcus pneumoniae.

We studied the transcriptomic response of Streptococcus pneumoniae to the fluoroquinolone moxifloxacin at a concentration that inhibits DNA gyrase. Treatment of the wild-type strain R6, at a concentration of 10× the MIC, triggered a response involving 132 genes after 30 min of treatment. Genes from several metabolic pathways involved in the production of pyruvate were upregulated. These included 3 glycolytic enzymes, which ultimately convert fructose 6-phosphate to pyruvate, and 2 enzymes that funnel phosphate sugars into the glycolytic pathway. In addition, acetyl coenzyme A (acetyl-CoA) carboxylase was downregulated, likely leading to an increase in acetyl-CoA. When coupled with an upregulation in formate acetyltransferase, an increase in acetyl-CoA would raise the production of pyruvate. Since pyruvate is converted by pyruvate oxidase (SpxB) into hydrogen peroxide (H2O2), an increase in pyruvate would augment intracellular H2O2. Here, we confirm a 21-fold increase in the production of H2O2 and a 55-fold increase in the amount of hydroxyl radical in cultures treated during 4 h with moxifloxacin. This increase in hydroxyl radical through the Fenton reaction would damage DNA, lipids, and proteins. These reactive oxygen species contributed to the lethality of the drug, a conclusion supported by the observed protective effects of an SpxB deletion. These results support the model whereby fluoroquinolones cause redox alterations. The transcriptional response of S. pneumoniae to moxifloxacin is compared with the response to levofloxacin, an inhibitor of topoisomerase IV. Levofloxacin triggers the transcriptional activation of iron transport genes and also enhances the Fenton reaction.

Vacuum-assisted biopsy diagnosis of atypical ductal hyperplasia and patient management.

PURPOSE: This study sought to evaluate the accuracy of vacuum-assisted biopsy (VAB) in the diagnosis of atypical ductal hyperplasia (ADH) by determining the rate of VAB underestimation compared with definitive histology. In addition, an attempt was made to identify parameters that could help determine the most appropriate patient management. MATERIALS AND METHODS: We retrospectively reviewed 1,776 VAB procedures performed between November 1999 and January 2008 for suspicious subclinical breast lesions visible only at mammography. A total of 177 patients with a VAB diagnosis of pure ADH were studied. Patients with a diagnosis of ADH associated with other lesions (lobular intraepithelial neoplasia, papilloma), atypical lobular hyperplasia, lobular carcinoma in situ and any lesions with a microhistological diagnosis other than ADH were excluded. Mammographic appearance of lesions was as follows: 152 mostly clustered microcalcifications (86%); five opacities with microcalcifications (3%); 12 single opacities (3%); and eight parenchymal distortions (4%), of which five were without and three were with microcalcifications. In cases underestimated by VAB, we evaluated the extent of ADH within ducts and lobules. Based on results, patients were subdivided into two groups: ≤2 ADH foci; >2 ADH foci. Patients were subdivided into two groups: one was referred for surgery and the other for follow-up care. The decision to either perform or not perform surgery was based on combined analysis of the following parameters: patient age; risk factors in the patient's history; mammographic extent of microcalcifications; complete excision of microcalcifications at VAB; and final Breast Imaging Reporting and Data System (BI-RADS) assessment. RESULTS: In the first group (n=98), comparison of microhistology with final histology revealed that 19 cases of ADH had been underestimated by VAB. In the second group (n=79), six cases of ADH showed progression of the mammographic abnormality, which was subsequently confirmed by surgical biopsy. CONCLUSIONS: The most relevant parameters affecting the decision to proceed to surgical excision were lesion diameter >7 mm on mammography, >2 ADH foci, incomplete removal of the calcifications and a family and/or personal history of breast cancer. Although there are no definite mammographic predictors of malignancy, a radiological assessment of suspicious lesion in the presence of an additional equivocal parameter always warrants surgical management.

[Other models for training radiologists]. / Otros modelos de formación de radiólogos.

Different models for training radiologists are used in different countries. Considering the trend toward international homogenization, it is important to know the differences and common traits among different countries to enable us to adapt our programs to future changes. We review training programs in radiology in Europe, the United States, Canada, and some Latin American countries. We focus on the selection process, residency programs, research, certification, subspecialization, and maintaining certification. We found a wide variability among countries, although there are more similarities within continents.

Aortoenteric fistulas: spectrum of MDCT findings. / Fístula aortoentérica: Espectro de hallazgos en tomografía computarizada multidetector.

An aortoenteric fistula is an abnormal communication between the aorta and the gastrointestinal tract wall. The high mortality associated with this rare entity means it requires early accurate diagnosis. Aortoenteric fistulas are classified as primary when they develop on a native aorta that has not undergone an intervention and as secondary when they develop after vascular repair surgery. All radiologists need to be able to recognize the direct and indirect signs that might suggest the presence of an aortoenteric fistula. This article reviews the types of aortoenteric fistulas and their clinical and pathophysiological correlation, as well as the diagnostic algorithm, illustrating the most characteristic findings on multidetector computed tomography.

The surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy.

The near-Earth asteroid 162173 Ryugu, the target of the Hayabusa2 sample-return mission, is thought to be a primitive carbonaceous object. We report reflectance spectra of Ryugu's surface acquired with the Near-Infrared Spectrometer (NIRS3) on Hayabusa2, to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micrometers was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, which is consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.

The structural assembly switch of cell division protein FtsZ probed with fluorescent allosteric inhibitors.

FtsZ is a widely conserved tubulin-like GTPase that directs bacterial cell division and a new target for antibiotic discovery. This protein assembly machine cooperatively polymerizes forming single-stranded filaments, by means of self-switching between inactive and actively associating monomer conformations. The structural switch mechanism was proposed to involve a movement of the C-terminal and N-terminal FtsZ domains, opening a cleft between them, allosterically coupled to the formation of a tight association interface between consecutive subunits along the filament. The effective antibacterial benzamide PC190723 binds into the open interdomain cleft and stabilizes FtsZ filaments, thus impairing correct formation of the FtsZ ring for cell division. We have designed fluorescent analogs of PC190723 to probe the FtsZ structural assembly switch. Among them, nitrobenzoxadiazole probes specifically bind to assembled FtsZ rather than to monomers. Probes with several spacer lengths between the fluorophore and benzamide moieties suggest a binding site extension along the interdomain cleft. These probes label FtsZ rings of live Bacillus subtilis and Staphylococcus aureus, without apparently modifying normal cell morphology and growth, but at high concentrations they induce impaired bacterial division phenotypes typical of benzamide antibacterials. During the FtsZ assembly-disassembly process, the fluorescence anisotropy of the probes changes upon binding and dissociating from FtsZ, thus reporting open and closed FtsZ interdomain clefts. Our results demonstrate the structural mechanism of the FtsZ assembly switch, and suggest that the probes bind into the open clefts in cellular FtsZ polymers preferably to unassembled FtsZ in the bacterial cytosol.

Donor-derived Strongyloides stercoralis hyperinfection syndrome after simultaneous kidney/pancreas transplantation.

Most cases of strongyloidiasis associated with solid organ transplantation have been due to the reactivation of a latent infection in the recipient as a result of the immunosuppressive therapy; however, donor-derived infections are becoming increasingly frequent. The case of a patient who nearly died of a Strongyloides stercoralis hyperinfection after receiving simultaneous kidney/pancreas transplants is described herein. No specific parasitological tests were performed pre-transplantation, despite the fact that both the recipient and the donor originated from endemic areas. Serological analysis of the donor's serum performed retrospectively revealed the origin of the infection, which if it had been done beforehand would have prevented the serious complications. Current practice guidelines need to be updated to incorporate immunological and molecular techniques for the rapid screening of Strongyloides prior to transplantation, and empirical treatment with ivermectin should be applied systematically when there is the slightest risk of infection in the donor or recipient.

Capecitabine with/without mitomycin C: results of a randomized phase II trial of second-line therapy in advanced biliary tract adenocarcinoma.

PURPOSE: Advanced biliary tract adenocarcinoma (BTA) is a rare tumor with a poor prognosis. Since no standard salvage chemotherapy regimen exists, we explored the activity of capecitabine alone or combined with mitomycin C. METHODS: Patients aged 18-75 years and with KPS >50, with pathological diagnosis of BTA stratified based on site and stage of disease, were randomized to receive capecitabine 2000 mg/m(2) day 1-14 alone (ARM A) or in combination with mitomycin C 6 mg/m(2) day 1 (ARM B) as second-line therapy. Cycles were repeated in both arms every 3 weeks. Tumor assessment was performed every 2 months. The primary endpoint was the probability of being progression free at 6 months (PFS-6) from treatment start. According to the Fleming design, the study aimed to enroll 26 pts per arm. An exploratory endpoint was to assess thymidylate synthase (TS) and thymidine phosphorylase (TP) expression, as biomarkers predictive for clinical outcomes of capecitabine treatment. RESULTS: Between October 2011 and 2013, 57 metastatic pts were enrolled: ARM A/B 28/29. Accordingly, 55 (26/29) pts were assessable for the primary endpoint: 2 (8%) ARM A and 3 (10%) ARM B pts were PFS-6. Main G3-4 toxicities were: hand-foot syndrome and transaminitis in 4/0%, and thrombocytopenia, diarrhea and fatigue in 0/3% of pts. No statistically significant correlation was found between TS or TP expression and pts' outcome. CONCLUSIONS: Since capecitabine yielded a disappointing outcome and the addition of mitomycin C did not improve the results, new therapeutic strategies need to be explored to improve survival in this disease setting.

Effects of oxodipine and elgodipine on (+)-[3H]-isradipine binding to cardiac and vascular membranes: cardiovascular selectivity.

We studied the effects of six dihydropyridines on the specific binding of (+)-[3H]-isradipine to vascular (portal vein) and cardiac isolated membranes to achieve the relative cardiovascular selectivity of these compounds. Elgodipine, (+)-oxodipine and nifedipine had a significantly higher affinity for the vascular L-type calcium channel than for the cardiac calcium channel while nicardipine showed opposite properties. The other dihydropyridines (nitrendipine and (+)-isradipine) had similar affinities for the cardiac and vascular calcium channels. As the membrane potential of isolated membranes is about 0 mV, these results suggest that the differences in binding of these dihydropyridines to L-type calcium channels in vascular and cardiac cells may be attributed to differences in the molecular structure of these calcium channels.

[Serous oligocystic adenoma of the pancreas]. / Adenoma seroso oligoquístico del páncreas.

Serous oligocystic or macrocystic adenoma of the pancreas is a very uncommon morphological variant of what was classically termed microcystic adenoma of the pancreas. This is a benign neoplasm; however, its radiological appearance mimicks that of potentially malignant mucinous neoplasms of the pancreas. Therefore, radiologists need to be familiar with this entity to ensure the most appropriate therapeutic management and help to avoid unnecessary surgery.

Pharmacological study of the new mucolytic drug N-guanyl-cysteine.

The pharmacological evaluation of N-guanyl-cysteine (IQB-782) is reported. This new cysteine derivative shows a potent mucolytic-expectorant activity in different test systems. Thus, IQB-782 protects rats against tobacco-smoke-induced respiratory airway obstruction, increases the tracheo-bronchial mucus secretion in rabbits and increases the pulmonary excretion of fluorescein in mice, an index of broncho-secretagogue activity. Like other mucolytics, IQB-782 is also effective in vitro in reducing the viscosity of a suspension of gastric mucin. This new drug is apparently devoid of any cardiovascular or autonomic activity and shows a moderate CNS depressant effect. IQB-782 is consequently a new thiol derivative which may offer some advantages in the treatment of different types of obstructive pulmonary disease.

Constipation and megacolon in rats related to treatment with oxodipine, a calcium antagonist.

The constipatory effects of oxodipine, a dihyrdopyridine-type calcium antagonist, have been described in a 3-mo, 12-mo, and 30-mo feeding toxicity study in rats. This paper reports the occurrence of megacolon in rats as a result of the constipatory effects of chronic administration of oxodipine. The first mortality due to oxodipine was seen after about 1 yr of treatment at a dose of 225 mg/kg/day. The toxic effects noted were dose-, time-, and sex-related. Female rats appeared more sensitive to the constipatory effects of the drug. The dose at which the effect occurred in both male and female rats was from about 75 to 675 times the recommended therapeutic dose for humans. To the best knowledge of the authors, this is the first report of a calcium channel blocker causing constipation in rats.

Effect of oxodipine, a novel dihydropyridine calcium channel blocker, in neurogenic hypertensive dogs.

The effects of an acute intravenous injection of oxodipine (5, 20 and 50 micrograms/kg), a new dihydropyridine calcium channel blocker, on blood pressure and heart rate were investigated in arterial neurogenic hypertension elicited in anesthetized dogs by acute sinoaortic denervation. This model is associated with disruption of baroreflex pathways and heart denervation, allowing a direct investigation of the effects of the drug on heart rate and blood vessels. The low dose (5 micrograms/kg) of oxodipine remained ineffective, whereas doses of 20 and 50 micrograms/kg of oxodipine elicited a decrease in blood pressure with no change in heart rate. These results suggest that, in contrast to other first generation dihydropyridines, oxodipine exerts a relatively specific action on blood vessels without significant intrinsic negative chronotropic properties in anesthetized sinoaortic-denervated dogs.

The fate of altered hepatocytic foci as a result of treatment with oxodipine, a calcium channel blocker.

The dietary administration of the calcium channel blocker oxodipine to Fischer (F344) rats for 12 and 30 months resulted in increased incidence of altered hepatocytic foci (AHF). As the Environmental Protection Agency (EPA) regards AHF as potentially precancerous it is important to accumulate experimental evidence which may negate this theory. In the case of oxodipine we proved that with dosages close to maximum tolerated dose (MTD) for prolonged periods no hepatic neoplasms were produced. The possible nature of such AHF is discussed.

Anti-ischaemic and haemodynamic effects of elgodipine, a potent new generation calcium antagonist, in chronic stable angina.

The effects of oral elgodipine, a new dihydropyridine calcium antagonist on ischaemia and left ventricular function were assessed by a single blind placebo controlled study in 12 patients with chronic stable angina. Graded treadmill exercise and echocardiography/Doppler were performed before and 90 min after single oral doses of elgodipine of 20 mg, 40 mg and 60 mg, or placebo, given at weekly intervals. Elgodipine significantly increased exercise time by 1.1, 2.0 and 2.4 min, (P < 0.001 in each case) and time to onset of angina by 1.1 (P < 0.01), 1.9 (P < 0.001) and 2.6 min (P < 0.001) with increasing doses of the drug. Angina was abolished in 50% of patients with significant improvement in ST depression at peak exercise (P < 0.001) with the 60 mg dose. Blood pressure fell significantly at rest and peak exercise with a corresponding significant increase in heart rate. Ejection fraction was increased by 7.8% (P < 0.001) and 8.4% (P < 0.001) as was the stroke volume by 9.3 ml (P < 0.001) and 12.5 ml (P < 0.001) at 40 mg and 60 mg respectively. Peak mitral A to E velocity ratio and total peripheral resistance decreased significantly in a dose related linear trend. Only minor side effects were noted and no patient required withdrawal from the study. The results demonstrate that oral elgodipine is a potent anti-ischaemic agent. An improvement in the echocardiographic parameters of left ventricular systolic and diastolic function was also seen.

Electrophysiological and radioligand binding studies of elgodipine and derivatives in portal vein myocytes.

The effects of a novel dihydropyridine, elgodipine, and of three derivatives have been studied on the calcium channel currents of isolated cells from rat portal vein by the patch-clamp technique, and on specific (+)-[3H]isradipine binding to vascular membranes. Elgodipine inhibited both T- and L-type calcium channels in a concentration-dependent manner. Half-inhibitions of T- and L-type calcium channel current were obtained at concentrations of 32 and 2.3 nM, respectively. Currents activated repetitively were similarly inhibited than those after a rest period, indicating absence of use-dependent inhibition by elgodipine. When cells were held at depolarized membrane potentials at which T- or L-type calcium channels were inactivated, the inhibitory effects of elgodipine were enhanced on both calcium channel currents, indicating that the elgodipine-induced inhibition was voltage-dependent. The elgodipine concentration which blocked the inactivated calcium channels were 5 to 7 times lower than those which blocked the resting calcium channels. The inhibition constant for elgodipine obtained from the displacement of (+)-[3H]isradipine binding to the L-type calcium channels in vascular membranes was identical to the dissociation constant calculated from electrophysiological data on inactivated calcium channels. At concentrations that completely inhibited calcium channels, elgodipine had no effect on chloride and potassium channels, and did not interfere with the intracellular calcium stores.(ABSTRACT TRUNCATED AT 250 WORDS)

Thickening of the adrenal zona glomerulosa in dogs induced by oxodipine, a calcium channel blocker.

Subchronic effects of oxodipine, a calcium channel blocker affecting the adrenal gland of the dog, are described. Thirteen wk of treatment at a high dose (24 mg/kg/day) of oxodipine resulted in drug-induced thickening of the zona glomerulosa and increased stimulation of its secretory activity. It is postulated that subchronic administration of oxodipine at this dosage resulted in a decrease in blood pressure, with uninterrupted stimulation of the adrenal zona glomerulosa to release aldosterone, causing an increase in the width of this portion of the gland involving cellular hyperplasia. Support for this indirect effect is found in the increased presence of renin granules in the juxtaglomerular apparatus.

Gingival hyperplasia in dogs induced by oxodipine, a calcium channel blocking agent.

Subchronic oral exposure of dogs to Oxodipine, a new calcium channel blocker of the dihydropyridine-type, resulted in dose-related gingival hyperplastic changes. The doses at which an effect was elicited were 24 and 73 times the intended therapeutic dose for man. The effects were first noted after 7 weeks of treatment, and were limited to the high and intermediate dose groups of both sexes. Macroscopically, a generalized enlargement of the maxillary and mandibular facial and lingual gingivae were noted. The histological changes were similar to those described in man for Nifedipine and hydantoin-related drugs. An increase in the activity of alkaline phosphatase and a decrease in alanine aminotransferase was demonstrated. This article is the first to describe gingival hyperplasia in dogs induced in a dose-dependent manner by a calcium channel blocker.

Drug-induced decrease of serum alanine and aspartate aminotransferase activity in the rat, as a result of treatment with oxodipine, a new calcium channel blocker.

Chronic oral administration of oxodipine, a new calcium channel blocker, resulted in a reduction in the blood enzyme activity of alanine and aspartate aminotransferase. The reductions were both time and dose related. The decline in enzyme activities was accompanied by microscopic hepatic changes, which in the opinion of the authors should have been associated with an increase in the enzyme activities of alanine aminotransferase and aspartate aminotransferase. The effect was only partially reversed one month after the cessation of oxodipine treatment.