QSAR study on the antimalarial activity of Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) inhibitors

Plasmodium falciparum, the most fatal parasite that causes malaria, is responsible for over one million deaths per year. P. falciparum dihydroorotate dehydrogenase (PfDHODH) has been validated as a promising drug development target for antimalarial therapy since it catalyzes the rate-limiting step for DNA and RNA biosynthesis. In this study, we investigated the quantitative structure-activity relationships (QSAR) of the antimalarial activity of PfDHODH inhibitors by generating four computational models using a multilinear regression (MLR) and a support vector machine (SVM) based on a dataset of 255 PfDHODH inhibitors. All the models display good prediction quality with a leave-one-out q(2) >0.66, a correlation coefficient (r) >0.85 on both training sets and test sets, and a mean square error (MSE) <0.32 on training sets and <0.37 on test sets, respectively. The study indicated that the hydrogen bonding ability, atom polarizabilities and ring complexity are predominant factors for inhibitors' antimalarial activity. The models are capable of predicting inhibitors' antimalarial activity and the molecular descriptors for building the models could be helpful in the development of new antimalarial drugs.

A new descriptor for computer-aided diagnosis of EUS imaging to distinguish autoimmune pancreatitis from chronic pancreatitis

BACKGROUND AND AIMS

Computer-aided diagnosis of EUS images was quite useful in differentiating pancreatic cancer from normal tissue and chronic pancreatitis. This study investigated the feasibility of using computer-aided diagnostic techniques to extract EUS image parameters to distinguish autoimmune pancreatitis from chronic pancreatitis.

METHODS

A new descriptor, local ternary pattern variance, was introduced to improve the performance of the classification model. Patients with autoimmune pancreatitis (n = 81) or chronic pancreatitis (n = 100) were recruited for this study. Representative EUS images were selected, and 115 parameters from 10 categories were extracted from the region of interest. Distance-between-class and sequential forward selection algorithms were used for their ideal combination of features that allowed a support vector machine predictive model to be built, trained, and validated. The accuracy, sensitivity, specificity, positive predictive values (PPVs), and negative predictive values (NPVs) were used to evaluate the performance of experimental results.

RESULTS

Fourteen parameters from 3 categories were selected as an ideal combination of features. The sample set was randomly divided into a training set and a testing set by using two different algorithms-the leave-one-out algorithm and the half-and-half method. The half-and-half method yielded an average (± standard deviation) accuracy of 89.3 ± 2.7%, sensitivity of 84.1 ± 6.4%, specificity of 92.5 ± 3.3%, PPV of 91.6 ± 3.7%, and NPV of autoimmune pancreatitis of 88.0 ± 4.1%.

CONCLUSIONS

This study shows that, with the local ternary pattern variance textural feature, computer-aided diagnosis of EUS imaging may be valuable to differentiate autoimmune pancreatitis from chronic pancreatitis. Further refinement of such models could generate tools for the clinical diagnosis of autoimmune pancreatitis.

Abstract POSTER-THER-1419: Chk1 inhibitor (MK8776) enhances cytotoxicity of gemcitabine in select patient-derived ovarian tumorgraft models

Purpose: Treatment of recurrent ovarian cancer is limited by low response rates to salvage chemotherapy. Novel small molecule inhibitors to Chk1 (checkpoint kinase 1) have been proposed to potentiate the cytotoxic effect of one such salvage treatment, gemcitabine, by interrupting the DNA damage repair pathway. Patient derived tumorgrafts were characterized by responsiveness to gemcitabine +/- MK8776 (Chk1 inhibitor). Response was correlated with markers of Chk1 activity.

Methods: Patient-derived tumorgraft models were created from patients undergoing surgery for epithelial ovarian cancer. Gemcitabine response was characterized in five high-grade serous models (PH044, PH048, PH070, PH080, and PH110). Two models (PH048 and PH080) were treated with gemcitabine monotherapy (240 mg/kg qweek x 4 doses), MK8776 monotherapy (32 mg/kg qweek x 4 doses), and with combination therapy (Gemcitabine 190 mg/kg and MK8776 32 mg/kg qweek x 4 doses). Animals were monitored for cytotoxicity, and tumors were measured weekly with ultrasound. Response to gemcitabine and to combination therapy was correlated to immunohistochemistry of γH2AX and immunoblotting for p345-Chk1 and p296-Chk1.

Results: Gemcitabine monotherapy did not affect tumor growth in two models (PH044 and PH048). Significant in vivo response to gemcitabine was seen in PH070 and PH080. Significant growth attenuation but not tumor regression was seen in PH110. MK8776 did not have any effect on tumor growth as monotherapy or in combination with gemcitabine in the gemcitabine resistant model, PH048. In contrast, in a gemcitabine sensitive model, PH080, MK8776 monotherapy significantly attenuated tumor growth, and there was a trend for MK8776 to potentiate the cytotoxic effects of gemcitabine in PH080 (p=0.16). Final tumor weights in the PH080 model after 4 doses of chemotherapy were 1.7 g (90%CI: 1.5-1.9g), 0.3g (90%CI: 0.18-0.35g), and 0.14g (90%CI: 0.08-.19g) in the control, gemcitabine alone, and gemcitabine with MK8776 groups respectively.

Decrease in the tumor auto-phosphorylation of Chk1 at Serine-296 was observed in some, but not all models in response to MK8766 treatment. γH2AX increased in response to the addition of MK8776 to gemcitabine.

Conclusions: Chk1 inhibition may enhance the activity of gemcitabine in some, but not all ovarian tumors. Further work is needed to find markers that will predict response to Chk1 inhibitors to help select patients for future clinical trials. While pChk1-S296 previously demonstrated potential utility as a biomarker of Chk1 inhibition, in vivo assessments of its differential expression may demonstrate the unreliability of this marker. This work supports the use of patient derived tumorgrafts in drug development for ovarian cancer.

Citation Format: A Kumar, S Weroha, M Becker, X Hou, S Greiner, L Karnitz, P Haluska. Chk1 inhibitor (MK8776) enhances cytotoxicity of gemcitabine in select patient-derived ovarian tumorgraft models [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr POSTER-THER-1419.

Ecto-5'-nucleotidase (CD73) is involved in chronic cerebral hypoperfusion-induced white matter lesions and cognitive impairment by regulating glial cell activation and pro-inflammatory cytokines

Recent studies have demonstrated that inflammatory and immune mechanisms play important roles in the progression of chronic cerebral hypoperfusion (CCH)-induced white matter lesions (WMLs). As an endogenous neuromodulator in the brain, the extracellular levels of adenosine represent a critical endogenous mechanism for the regulation of immune and inflammatory responses. Ecto-5'-nucleotidase (CD73), which dephosphorylates AMP to adenosine, is considered to catalyze the rate-limiting step in the generation of extracellular adenosine. However, the role of CD73 in the development of CCH-induced WMLs remains unclear. In the present study, we investigated the expression and activity of CD73 using immunohistochemistry, Western blot analysis and measurements of the rate of AMP hydrolysis in a mouse model of CCH via bilateral common carotid artery stenosis (BCAS) surgery. Moreover, C57BL/6-CD73 knockout (KO) and their wild-type littermates were subjected to BCAS surgery to further investigate the functional roles of CD73 in the WMLs. White matter (WM) changes, astrocyte and microglia proliferation, proinflammatory cytokine levels in the corpus callosum and cognitive function were assessed on the 30th day after BCAS. The results indicated that CD73 expression and activities significantly increased in the corpus callosum on the 30th day after BCAS. Moreover, CD73 deficiency exacerbated CCH-induced WMLs and cognitive impairment. More reactive astrocytes and microglia were observed in the corpus callosum in CD73-KO mice. CD73 deficiency significantly increased the levels of proinflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β) in the BCAS model of CCH. These findings suggest that CD73 plays a protective role in the development of CCH-induced WMLs and cognitive impairment via the regulation of glial cell activation and proinflammatory cytokine expression.

Contrast-enhanced harmonic endoscopic ultrasound-guided fine-needle aspiration in the diagnosis of solid pancreatic lesions: a retrospective study

BACKGROUND

The negative predictive value of endoscopic ultrasonography-guided fine needle aspiration for the diagnosis of solid pancreatic lesions remains low, and the biopsy specimens are sometimes inadequate for appropriate pathological diagnosis.

AIMS

To evaluate the usefulness of a novel method of contrast-enhanced harmonic endoscopic ultrasonography-guided fine-needle aspiration for the differential diagnosis and adequate sampling of solid pancreatic lesions.

METHODS

Patients with a diagnosis of solid pancreatic lesions who underwent fine-needle aspiration guided by contrast-enhanced harmonic endoscopic ultrasonography or by endoscopic ultrasonography from October 2010 to July 2013 were retrospectively identified and classified into the CH-EUS or EUS group, respectively. Surgical pathology and/or follow-up results were defined as the final diagnosis. Operating characteristics and adequacy of biopsy specimens by fine-needle aspiration were compared between the two groups.

RESULTS

Operating characteristics for contrast-enhanced harmonic endoscopic ultrasonography-guided fine-needle aspiration in solid pancreatic lesions were as follows: area under the curve = 0.908, sensitivity = 81.6%, specificity = 100%, positive predictive value = 100%, negative predictive value = 74.1%, and accuracy = 87.9%. The percentage of adequate biopsy specimens in the CH-EUS group (96.6%) was greater than that in the EUS group (86.7%).

CONCLUSION

Simultaneous contrast-enhanced harmonic endoscopic ultrasonography during fine-needle aspiration is useful for improving the diagnostic yield and adequate sampling of solid pancreatic lesions.

Relationship between American Society of Anesthesiologists (ASA) grade and 1-year mortality in nonagenarians undergoing hip fracture surgery

This study retrospectively reviewed 327 nonagenarians who underwent hip fracture surgery at six hospitals. Functional status, postoperative complications, and 1-year mortality were evaluated, and relationships between these factors and American Society of Anesthesiologists (ASA) grade were analyzed. ASA grade was significantly associated with postoperative complications and 1-year mortality.

INTRODUCTION

Few previous studies have reported outcomes after hip fracture in nonagenarians, and these studies did not report significant associations between ASA grade and mortality. However, most of these studies included only a small number of patients from a single hospital. This study aimed to evaluate the relationships between ASA grade and functional status, postoperative complications, and mortality rate in nonagenarians undergoing hip fracture surgery.

METHODS

This study included 327 nonagenarians who underwent hip fracture surgery between January 2000 and December 2012. Patients with open fractures, subtrochanteric fractures, polytrauma, and pathological fractures were excluded. The medical records and X-rays were retrospectively reviewed. The relationships between ASA grade and functional status, postoperative complications, and 1-year mortality were analyzed.

RESULTS

There were significant associations between the ASA grade and the rates of postoperative complications and 1-year mortality (both p < 0.05). All pairwise comparisons showed significant differences in postoperative complication rates between ASA grades (all p < 0.05). All pairwise comparisons, except for grades I vs. II and grades II vs. III, also showed significant differences in mortality rates between ASA grades (all p < 0.05). There were significant associations between the preoperative ability to manage activities of daily living and the rates of postoperative complications and 1-year mortality (both p < 0.05).

CONCLUSIONS

ASA grade was significantly associated with the rates of postoperative complications and 1-year mortality in nonagenarians undergoing hip fracture surgery. The preoperative functional status was also significantly associated with these outcomes.

Isolation of lactic acid bacteria from pao cai, a Chinese traditional fermented vegetable, with inhibitory activity against Salmonella associated with fresh-cut apple, using a modelling study

AIMS

To isolate lactic acid bacteria (LAB) from pao cai, a Chinese traditional fermented vegetable, with outstanding inhibitory activity against Salmonella inoculated on fresh-cut apple, using a modelling method.

METHODS AND RESULTS

Four kinds of pao cai were selected. A total of 122 isolates exhibited typical LAB characteristics: Gram-positive and catalase negative, among which 104 (85·24%) colonies showed antibacterial activity against Salmonella by the well diffusion assay. Four colonies showing maximum antibacterial radius against Salmonella were selected to co-inoculate with Salmonella on fresh-cut apple and stored at 10°C, further identified as three strains of Lactobacillus plantarum and one strain of Lactobacillus brevis by 16s rRNA gene sequence analysis. The modified Gompertz model was employed to analyse the growth of the micro-organisms on apple wedges. Two of the four selected strains showed antagonistic activity against Salmonella on fresh-cut apple, one of which, RD1, exhibited best inhibitory activity (Salmonella were greatly inhibited when co-inoculated with RD1 at 10°C at 168 h). No deterioration in odour or appearance of the apple piece was observed by the triangle test when fresh-cut apple was inoculated with RD1.

CONCLUSIONS

The mathematical modelling method is essential to select LAB with outstanding inhibitory activity against Salmonella associated with fresh-cut apple. LAB RD1 holds promise for the preservation of fresh-cut apple.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provided a new method on fresh-cut product preservation. Besides, to make the LAB isolating procedure a more correct one, this study first added the mathematical modelling method to the isolating procedure.

Graphical user interface for yield and dose estimations for cyclotron-produced technetium

The cyclotron-based (100)Mo(p,2n)(99m)Tc reaction has been proposed as an alternative method for solving the shortage of (99m)Tc. With this production method, however, even if highly enriched molybdenum is used, various radioactive and stable isotopes will be produced simultaneously with (99m)Tc. In order to optimize reaction parameters and estimate potential patient doses from radiotracers labeled with cyclotron produced (99m)Tc, the yields for all reaction products must be estimated. Such calculations, however, are extremely complex and time consuming. Therefore, the objective of this study was to design a graphical user interface (GUI) that would automate these calculations, facilitate analysis of the experimental data, and predict dosimetry. The resulting GUI, named Cyclotron production Yields and Dosimetry (CYD), is based on Matlab®. It has three parts providing (a) reaction yield calculations, (b) predictions of gamma emissions and (c) dosimetry estimations. The paper presents the outline of the GUI, lists the parameters that must be provided by the user, discusses the details of calculations and provides examples of the results. Our initial experience shows that the proposed GUI allows the user to very efficiently calculate the yields of reaction products and analyze gamma spectroscopy data. However, it is expected that the main advantage of this GUI will be at the later clinical stage when entering reaction parameters will allow the user to predict production yields and estimate radiation doses to patients for each particular cyclotron run.

Antiemesis effect and brain fMRI response of gastric electrical stimulation with different parameters in dogs

BACKGROUND

The aims of this study were to investigate the effect of gastric electrical stimulation (GES) with different parameters on emesis induced by apomorphine, and possible center mechanisms by brain functional magnetic resonance imaging (fMRI).

METHODS

Six dogs implanted with electrodes on gastric serosa were used in this study. Part 1: Apomorphine was injected in the control session and GES sessions. GESs with different parameters were applied in GES session. Gastric slow waves and emesis and behaviors suggestive of nausea were recorded in each session. Part 2: Each dog was anesthetized and given GESs with different parameters or sham stimulation for 15 min after baseline (5 min), respectively. The location of cerebral activation induced by GES was investigated by fMRI.

KEY RESULTS

Apomorphine induced emesis and behaviors suggestive of nausea, and gastric dysrhythmia. The emesis frequency in control session was 5.5 ± 0.99, and symptoms score was 22.17 ± 1.01. GES with short pulse and long pulse could not improve emesis and symptoms induced by apomorphine. The emesis frequency (4.5 ± 0.76 in short pulse and 6.33 ± 1.05 in long pulse) and symptoms scores had no significant difference compared to control session (each p > 0.05). GES with trains of short pulse reduced emesis time frequency (3.83 ± 0.7, p = 0.042 vs control) and symptoms score (p = 0.037 vs control) obviously. Brain fMRI showed that GES with short pulse and long pulse activated brain stem region, and trains of short pulse made amygdala and occipital lobe activation.

CONCLUSIONS & INFERENCES

Apomorphine induced emesis and gastric dysrhythmia. GES with trains of short pulses relieves emetic responses through activation of amygdala region.

Schistosoma japonicum: susceptibility of neonate mice born to infected and noninfected mothers following subsequent challenge

This study was to investigate the differences between neonate mice born to Schistosoma japonicum-infected mothers and those born to noninfected mothers in subsequent challenge. The intensity of infection (evidenced by worm burden and liver egg burden) and liver immunopathology (number and size of liver granulomas) were significantly reduced in neonates from infected mothers (I.M.) compared with neonates from noninfected mothers (N.M.). Anti-soluble worm antigen of S. japonicum (SWA) IgG could be detected in sera of neonates from I.M. (N.N./I.M.) at 1 week after delivery, remained a plateau for 2 weeks and gradually decreased until 8 weeks of age. Parasite-specific IgM was not detected in sera from N.N./I.M. at any time after delivery. At 6 weeks after infection, the level of anti-SWA IgG in infected neonates from I.M. (I.N./I.M.) was significantly higher than that of infected neonates from N.M. (I.N./N.M.). In addition, production of IFN-γ, IL-12 and TGF-β by cultured splenocytes from I.N./I.M. was significantly increased, while the level of IL-4 was significantly decreased when compared to those from I.N./N.M.. These data demonstrate that congenital exposure to schistosomiasis japonica may render neonatal mice born to I.M. less susceptible to subsequent challenge and result in down-regulation of both infection intensity and immunopathology.

Inferred cosmic-ray spectrum from Fermi large area telescope γ-ray observations of Earth's limb

Recent accurate measurements of cosmic-ray (CR) species by ATIC-2, CREAM, and PAMELA reveal an unexpected hardening in the proton and He spectra above a few hundred GeV, a gradual softening of the spectra just below a few hundred GeV, and a harder spectrum of He compared to that of protons. These newly discovered features may offer a clue to the origin of high-energy CRs. We use the Fermi Large Area Telescope observations of the γ-ray emission from Earth's limb for an indirect measurement of the local spectrum of CR protons in the energy range ∼90  GeV-6  TeV (derived from a photon energy range 15 GeV-1 TeV). Our analysis shows that single power law and broken power law spectra fit the data equally well and yield a proton spectrum with index 2.68±0.04 and 2.61±0.08 above ∼200  GeV, respectively.