Biochemical characterization of the Pseudomonas aeruginosa 101/1477 metallo-beta-lactamase IMP-1 produced by Escherichia coli

The blaIMP gene coding for the IMP-1 metallo-beta-lactamase produced by a Pseudomonas aeruginosa clinical isolate (isolate 101/1477) was overexpressed via a T7 expression system in Escherichia coli BL21 (DE3), and its product was purified to homogeneity with a final yield of 35 mg/liter of culture. The structural and functional properties of the enzyme purified from E. coli were identical to those of the enzyme produced by P. aeruginosa. The IMP-1 metallo-beta-lactamase exhibits a broad-spectrum activity profile that includes activity against penicillins, cephalosporins, cephamycins, oxacephamycins, and carbapenems. Only monobactams escape its action. The enzyme activity was inhibited by metal chelators, of which 1,10-o-phenanthroline and dipicolinic acid were the most efficient. Two zinc-binding sites were found. The zinc content of the P. aeruginosa 101/1477 metallo-beta-lactamase was not pH dependent.     

Second-line treatments for Advanced Hepatocellular Carcinoma: A Systematic Review and Bayesian Network Meta-analysis

Background & Aims

A plethora of second-line therapies have been recently introduced for hepatocellular carcinoma (HCC) treatment with promising results. A meta-analysis of second-line treatments for HCC has been performed to better tailor their use based on improved patient stratification and to identify the best available option.

Methods

Pubmed, Scopus, Web of Science, and ClinicalTrials.gov were searched for randomized controlled trials evaluating second-line treatment for advanced HCC in patients already treated with sorafenib. The primary outcome was overall survival (OS). Secondary outcomes were progression-free survival (PFS) and drug withdrawal due to adverse events. Network meta-analyses were performed considering placebo as the basis for comparison in efficacy and safety analyses. Subgroup stratification considered gender, age, sorafenib-responsiveness and drug tolerability, viral infection, macrovascular invasion, HCC extrahepatic spread, performance status, and alpha-fetoprotein levels.

Results

Fourteen phase II or III randomized controlled trials, involving 5,488 patients and 12 regimens, were included in the analysis. Regorafenib (hazard ratio (HR)?=?0.63, 95% confidence interval (CI)?=?0.50–0.79), cabozantinib (HR?=?0.76, 95% CI?=?0.63–0.92), and ramucirumab (HR?=?0.82, 95% CI?=?0.70–0.76) significantly prolonged OS compared with placebo. Cabozantinib (HR?=?0.44, 95% CI?=?0.36–0.52), regorafenib (HR?=?0.46, 95% CI?=?0.37–0.56), ramucirumab (HR?=?0.54, 95% CI?=?0.43–0.68), brivanib (HR?=?0.56, 95% CI?=?0.42–0.76), S-1 (HR?=?0.60, 95% CI?=?0.46–0.77), axitinib (HR?=?0.62, 95% CI?=?0.44–0.87), and pembrolizumab (HR?=?0.72, 95% CI?=?0.57–0.90) significantly improved PFS compared with placebo. None of the compared drugs deemed undoubtedly superior after having performed a patients’ stratification.

Conclusions

The results of this network meta-analysis suggest the use of regorafenib and cabozantinib as second-line treatments in HCC.

     

Residual perfusion defects in patients with pulmonary embolism are related to impaired fibrinolytic capacity

Background

Few studies investigated the relationship between fibrinolysis abnormalities and residual pulmonary perfusion defects after acute pulmonary embolism (PE).

Objective

To assess the fibrinolytic profile in patients with prior PE in relation to the extent of scintigraphically detectable residual perfusion abnormalities.

Patients and methods

We studied 71 consecutive patients with a prior episode of PE, who were examined after one year of the incident embolic event, and at least one month after anticoagulation withdrawal. They underwent lung scintigraphy to assess the recovery of pulmonary perfusion, echocardiography and chest radiography to look for signs of pulmonary hypertension. Clot formation and lysis were evaluated by two turbidimetric methods: Clot and Lysis Assay and Clot Lysis Time. We also measured the in vitro plasmin-mediated lysis of fibrin from purified fibrinogen, and the circulating levels of fibrinolytic inhibitors. The sample was split in two categories based on the extent of residual perfusion defects: < 10% (n = 53), ≥ 10% (n = 18).

Results

Patients with perfusion defects > 10% had significantly longer lysis time (p < 0.05), and higher levels of plasminogen activator inhibitor-1 (p < 0.01) than those with perfusion defects < 10%. The time interval between symptoms onset and PE diagnosis (time-to-diagnosis) was significantly longer in patients with perfusion defects > 10% than in the others (p = 0.005). In multivariate logistic regression, both lysis time and time-to-diagnosis were independently associated with perfusion defects > 10% (p < 0.001). None of the sampled patients had echocardiographic or radiologic signs of pulmonary hypertension.

Conclusion

Prolonged time-to-diagnosis and fibrinolysis imbalance are independent predictors of incomplete perfusion recovery after acute PE.     

Breast lesion detection and characterization at contrast-enhanced MR mammography: gadobenate dimeglumine versus gadopentetate dimeglumine

PURPOSE: To prospectively and intraindividually compare equivalent (0.1 mmol per kilogram of body weight) doses of gadobenate dimeglumine and gadopentetate dimeglumine for accuracy of detection and characterization of breast lesions at contrast material-enhanced magnetic resonance (MR) mammography. MATERIALS AND METHODS: Ethics committee approval and informed consent were obtained. Twenty-six consecutive women (mean age, 47.8 years) suspected of having a breast tumor at mammography and sonography underwent two identical MR examinations at 1.5 T; examinations were separated by more than 48 hours but less than 72 hours. A T1-weighted three-dimensional gradient-echo sequence was used, and images were acquired before and at 0, 2, 4, 6, and 8 minutes after randomized injection of gadopentetate dimeglumine or gadobenate dimeglumine at an identical flow rate of 2 mL/sec. Separate and combined assessment of unenhanced, contrast-enhanced, and subtracted images was performed blindly by two readers in consensus. Accuracy for lesion detection was determined against a final diagnosis based on findings at conventional mammography, sonography, and surgery. Sensitivity, specificity, positive and negative predictive values, and overall accuracy for malignant lesion identification were determined against histologic results. Data were analyzed with the McNemar test, proportional odds models, and analysis of variance. RESULTS: MR mammography with gadobenate dimeglumine depicted significantly (P = .003) more lesions (45 of 46) than did that with gadopentetate dimeglumine (36 of 46), and detected lesions were significantly (P < .001) more conspicuous with gadobenate dimeglumine. Confidence for characterization was significantly (P = .031) greater with gadobenate dimeglumine. Comparison of the contrast agents for their ability to help identify malignant lesions revealed significant (P = .02) superiority for gadobenate dimeglumine: Sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy for malignant lesion identification were, respectively, 94.7%, 100%, 100%, 80.0%, and 95.6% with gadobenate dimeglumine and 76.3%, 100%, 100%, 47.1%, and 80.4% with gadopentetate dimeglumine. Quantitative evaluation of signal intensity-time curves revealed significantly (P < .001) greater lesion enhancement with gadobenate dimeglumine. CONCLUSION: Detection of breast lesions and accurate identification of malignant lesions at MR imaging are significantly superior with gadobenate dimeglumine in comparison with gadopentetate dimeglumine.     

Autoimmune pancreatitis: multidetector-row computed tomography (MDCT) and magnetic resonance (MR) findings in the Italian experience

Multidetector-row computed tomography (MDCT) and magnetic resonance (MR) imaging are currently the most frequently performed imaging modalities for the study of pancreatic disease. In cases of suspected autoimmune pancreatitis (AIP), a dynamic quadriphasic (precontrast, contrast-enhanced pancreatic, venous and late phases) study is recommended in both techniques. In the diffuse form of autoimmune pancreatitis (DAIP), the pancreatic parenchyma shows diffuse enlargement and appears, during the MDCT and MR contrast-enhanced pancreatic phase, diffusely hypodense and hypointense, respectively, compared to the spleen because of lymphoplasmacytic infiltration and pancreatic fibrosis. During the venous phase of MDCT and MR imaging, the parenchyma appears hyperdense and hyperintense, respectively, in comparison to the pancreatic phase. In the delayed phase of both imaging modalities, it shows retention of contrast media. A “capsule-like rim” may be recognised as a peripancreatic MDCT hyperdense and MR hypointense halo in the T2-weighted images, compared to the parenchyma. DAIP must be differentiated from non-necrotizing acute pancreatitis (NNAP) and lymphoma since both diseases show diffuse enlargement of the pancreatic parenchyma. The differential diagnosis is clinically difficult, and dynamic contrast-enhanced MDCT has an important role. In the focal form of autoimmune pancreatitis (FAIP), the parenchyma shows segmental enlargement involving the head, the body-tail or the tail, with the same contrast pattern as the diffuse form on both modalities. FAIP needs to be differentiated from pancreatic adenocarcinoma to avoid unnecessary surgical procedures, since both diseases have similar clinical and imaging presentation. The differential diagnosis is clinically difficult, and dynamic contrast-enhanced MDCT and MR imaging both have an important role. MR cholangiopancreatography helps in the differential diagnosis. Furthermore, MDCT and MR imaging can identify the extrapancreatic manifestations of AIP, most commonly biliary, renal and retroperitoneal. Finally, in all cases of uncertain diagnosis, MDCT and/or MR follow-up after short-term treatment (2–3 weeks) with high-dose steroids can identify a significant reduction in size of the pancreatic parenchyma and, in FAIP, normalisation of the calibre of the upstream main pancreatic duct.     

Relationship between the magnitude of symptoms and the quality of life: a cluster analysis of lung cancer patients in Brazil

OBJECTIVE:

Lung cancer patients often experience profound physical and psychosocial changes as a result of disease progression or treatment side effects. Fatigue, pain, dyspnea, depression, and sleep disturbances appear to be the most common symptoms in such patients. The objective of the present study was to examine the prevalence of symptoms in lung cancer patients in order to identify subgroups (clusters) of patients, grouped according to the magnitude of the symptoms, as well as to compare the quality of life among the identified subgroups.

METHODS:

A cross-sectional study involving agglomerative hierarchical clustering. A total of 50 lung cancer patients were evaluated in terms of their demographic characteristics and their scores on three quality of life questionnaires, namely the 30-item European Organization for Research and Treatment of Cancer Core Quality of Life Questionnaire (EORTC QLQ-C30), the Functional Assessment of Cancer Therapy-Lung, and the Medical Outcomes Study 36-item Short-form Survey. The cluster analysis took into account the magnitude of the most prevalent symptoms as assessed by the EORTC QLQ-C30 symptom scale scores; those symptoms were fatigue, pain, dyspnea, and insomnia.

RESULTS:

Three clusters (subgroups)_of patients were identified on the basis of the magnitude of the four most prevalent symptoms. The three subgroups of patients were as follows: patients with mild symptoms (n = 30; 60%); patients with moderate symptoms (n = 14; 28%); and patients with severe symptoms (n = 6; 12%). The subgroup of patients with severe symptoms had the worst quality of life, as assessed by the total scores and by the integrated domains of all three instruments.

CONCLUSIONS:

This study highlights the importance of symptom cluster assessment as an important tool to assess the quality of life of patients with chronic diseases, such as lung cancer.     

Detection of small (≤2 cm) HCC in cirrhotic patients: added value of diffusion MR-imaging

Objectives

To evaluate the usefulness of the diffusion-weighted sequence in the detection of small (≤2 cm) hepatocellular carcinoma (HCC) in patients with cirrhosis.

Methods

Seventy cirrhotic patients with 93 HCCs underwent MR-Imaging at 1.5 T. MR acquisitions comprised unenhanced T1- and T2-weighted images and post-contrast Gd-BOPTA-enhanced T1W GRE-3D images acquired after approximately 25, 60, 180 s (dynamic phases) and 90 min (hepatobiliary phase). DWI was performed by a SSEPI sequence (b values 0, 50, 400, 800 s/mm²). Quantitative analysis was performed to establish significant difference of ADC values of benign lesions compared with that of HCC. Sensitivity, specificity, positive and negative predictive values and diagnostic accuracy of two different protocols with and without diffusion MRI sequence were also calculated and compared each other.

Results

A good inverse correlation was found between reference standard and ADC values (ρ = ?0.688). The mean ADC value of HCC was significantly lower than the mean value of benign focal liver lesions (p < 0.0001). No significant difference was reported in term of sensitivity, specificity, PPV, NPV and diagnostic accuracy between the two datasets. A trend to a better sensitivity was found when DWI images were considered.

Conclusions

The adjunction of DWI does not significantly improve the diagnostic accuracy in the detection of small HCC.     

Neoadjuvant oxaliplatin and 5-fluorouracil with concurrent radiotherapy in patients with locally advanced rectal cancer: a singleinstitution experience

Purpose

The aim of this study was to evaluate the rate of pathological response (PR), disease control and safety of neoadjuvant chemotherapy using oxaliplatin (OX) and 5-fluorouracil (5-FU) with concurrent radiotherapy for treating locally advanced rectal cancer.

Materials and methods

Between November 2002 and December 2010, 90 patients with locally advanced rectal cancer treated with neoadjuvant chemoradiotherapy (CRT) were retrospectively analysed. All patients underwent preoperative radiotherapy (45 Gy in 1.8-Gy fractions) with concurrent OX (80 mg/m2 i.v., day 1) and a 120-h continuous infusion of 5-FU (1,000 mg/m² per day). Surgery was performed within 6 weeks after completion of CRT treatment.

Results

Complete pathological response was obtained in six patients (6.7%), and 39 (43.3%) had their disease downstaged. The median follow-up period was 4.7 years (6 months to 9 years). Local recurrence occurred in two patients (2.2%), one of whom developed also liver metastases. Distant metastases not associated with local relapse occurred in 23 (25.6%) patients. Overall (OS) and disease-free (DFS) survival were 62.9% and 52.8%, respectively. CRT was well tolerated, with only one grade 3 (1.2%) haematological toxicity (neutropaenia).

Conclusions

Neoadjuvant systemic chemotherapy based on OX and 5-UC associated with radiotherapy is well tolerated, with good results in terms of pathological response, disease control and survival, in rectal cancer patients.