189 research outputs found
Comparative evaluation of the antimicrobial activity of Citrullus colocynthis immature fruit and seed organic extracts
Gastrointestinal problems, dermatological, gynaecological and pulmonary infections produced by micro-organisms are widespread in the entire globe. The treatment of these infections is mainly based on the use of synthetic drugs which have lost, in recent years, their effectiveness, due to the development of resistant strains and the rise of opportunistic fungal infections. Tunisian traditional medicine is a potential source of new remedies namely, Citrullus colocynthis Schrad. (Cucurbitaceae). Lyophilized aqueous and organic extracts from immature fruits and seeds were screened for activity against gram-negative (Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Vibrio parahaemolyticus and Vibrio alginolyticus) and gram-positive (Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, Listeria monocytogenes and Micrococcus luteus) bacteria and various Candida spp. (Candida glabrata, Candida albicans, Candida parapsilosis and Candida kreusei). Minimal inhibition concentrations (MICs) and minimal bactericidal/fungicidal concentrations (MBCs/MFCs) were used to investigate the antimicrobial activity. Extracts from the two C. colocynthis Schrad. organs, at immature state, inhibited the growth of all the tested strains. The highest antibacterial effects were obtained against E. coli (MIC = 0.006 mg/ml) with the fruit methanol and the seed petroleum extracts. Regarding the anticandidal activity assessment, seed extracts showed the lowest results. This study demonstrated the broad spectrum antimicrobial activity of C. colocynthis immature fruit and seed extracts.Key words: Citrullus colocynthis Schrad, fruits, seeds, organic extracts, antibacterial, anticandidal
antioxidant and anticandidal activities of the tunisian haplophyllum tuberculatum forssk a juss essential oils
Abstract Haplophyllum tuberculatum Forssk. is a medicinal plant growing in Tunisia. It is widely used in traditional medicine against gastro-intestinal problems, fevers, ear infections and rheumatisms. The present investigation evaluated the effects of leaves, stems and leaves + stems essential oils of Haplophyllum tuberculatum Forssk. and of their pure compounds on free radicals as well as their anticandidal activities. Screening for the antioxidant activity of the oils, R-(+)-limonene, S-(−)-limonene and 1-octanol was conducted by DPPH, ABTS and β-carotene/linoleic acid radical scavenging assays. The essentials oils and their compounds were screened for antifungal activity against four Candida species: Candida albicans ATCC 90028; Candida glabrata ATCC 90030; Candida parapsilosis ATCC 27853 and Candida krusei ATCC 6258. When compared with ascorbic acid as standard, it was found that the essential oils have a significant inhibition in scavenging free radicals, resulting in an important IC50. The pure compounds were inactive against the free radicals. The anticandidal test results showed that leaves, stems and leaves + stems oils strongly inhibited the growth of Candida krusei at 30 μg/mL leaves oils and 70 μg/mL for other oils and that moderately of the 3 other Candida species. The pure compound, 1-octanol, was active one against the candida species, with MIC-values between 0.07 and 1.25 mg/mL. In all in vitro assays, a significant correlation existed between the concentrations of the essential oils, the percentage inhibition of free radicals and of the growth inhibitory of tested candida species. The results indicate the essential oils may be applied for treating diseases related to free radicals, potentially to prevent cancer development and as an antifungal agent against Candida
Inhibitory Activity of Leaves Extracts of Citrullus colocynthis Schrad. on HT29 Human Colon Cancer Cells
Aims: Citrullus colocynthis is a plant endemic in Asia, Africa and in the Mediterranean basin. It is
used in folk medicine against infections, inflammations and cardiovascular and immune-related
diseases. There are further evidences of the use of Citrullus colocynthis Schrad in the treatment of
cancer in traditional practices. The present study aimed to determine the potential antiproliferative
effects of different Citrullus colocynthis leaf extracts on human cancer cells.
Methodology: Antiproliferative and antioxidant effects on HT-29 human colon cancer cells were
detected by MTS assay and a modified protocol of the alkaline Comet assay. In vitro antioxidant
activities of different leaf extracts were evaluated through DPPH, \u3b2-carotene/linoleic acid and
reducing power assays.
Results: The leaf chloroform extract exhibited the higher cell growth inhibitory activity without
induction of DNA damage; it showed to be able to significantly decrease DNA damage induced by
H2O2 (100 M). This antioxidant activity seems to be comparable to that of vitamin C (1 mM). Ethyl
acetate, acetone and methanol leaf extracts showed to be the most effective in reducing the stable
free DPPH radical (IC50 =113 g/ml), in transforming the Fe3+ to Fe2+ (IC50 = 134 \ub5g/ml) and in
inducing linoleic acid oxidation with an inhibition of 31.9 %.
Conclusion: Our results confirm the antiproliferative potential of Citrullus colocynthis Schrad. on
human cancer cells
An approximate empirical Bayesian method for large-scale linear-Gaussian inverse problems
We study Bayesian inference methods for solving linear inverse problems,
focusing on hierarchical formulations where the prior or the likelihood
function depend on unspecified hyperparameters. In practice, these
hyperparameters are often determined via an empirical Bayesian method that
maximizes the marginal likelihood function, i.e., the probability density of
the data conditional on the hyperparameters. Evaluating the marginal
likelihood, however, is computationally challenging for large-scale problems.
In this work, we present a method to approximately evaluate marginal likelihood
functions, based on a low-rank approximation of the update from the prior
covariance to the posterior covariance. We show that this approximation is
optimal in a minimax sense. Moreover, we provide an efficient algorithm to
implement the proposed method, based on a combination of the randomized SVD and
a spectral approximation method to compute square roots of the prior covariance
matrix. Several numerical examples demonstrate good performance of the proposed
method
Robust Online Hamiltonian Learning
In this work we combine two distinct machine learning methodologies,
sequential Monte Carlo and Bayesian experimental design, and apply them to the
problem of inferring the dynamical parameters of a quantum system. We design
the algorithm with practicality in mind by including parameters that control
trade-offs between the requirements on computational and experimental
resources. The algorithm can be implemented online (during experimental data
collection), avoiding the need for storage and post-processing. Most
importantly, our algorithm is capable of learning Hamiltonian parameters even
when the parameters change from experiment-to-experiment, and also when
additional noise processes are present and unknown. The algorithm also
numerically estimates the Cramer-Rao lower bound, certifying its own
performance.Comment: 24 pages, 12 figures; to appear in New Journal of Physic
SARS-CoV-2 infection in acute pancreatitis increases disease severity and 30-day mortality: COVID PAN collaborative study
Objective: There is emerging evidence that the pancreas may be a target organ of SARS-CoV-2 infection. This aim of this study was to investigate the outcome of patients with acute pancreatitis (AP) and coexistent SARS-CoV-2 infection. Design: A prospective international multicentre cohort study including consecutive patients admitted with AP during the current pandemic was undertaken. Primary outcome measure was severity of AP. Secondary outcome measures were aetiology of AP, intensive care unit (ICU) admission, length of hospital stay, local complications, acute respiratory distress syndrome (ARDS), persistent organ failure and 30-day mortality. Multilevel logistic regression was used to compare the two groups. Results: 1777 patients with AP were included during the study period from 1 March to 23 July 2020. 149 patients (8.3%) had concomitant SARS-CoV-2 infection. Overall, SARS-CoV-2-positive patients were older male patients and more likely to develop severe AP and ARDS (p<0.001). Unadjusted analysis showed that SARS-CoV-2-positive patients with AP were more likely to require ICU admission (OR 5.21, p<0.001), local complications (OR 2.91, p<0.001), persistent organ failure (OR 7.32, p<0.001), prolonged hospital stay (OR 1.89, p<0.001) and a higher 30-day mortality (OR 6.56, p<0.001). Adjusted analysis showed length of stay (OR 1.32, p<0.001), persistent organ failure (OR 2.77, p<0.003) and 30-day mortality (OR 2.41, p<0.04) were significantly higher in SARS-CoV-2 co-infection. Conclusion: Patients with AP and coexistent SARS-CoV-2 infection are at increased risk of severe AP, worse clinical outcomes, prolonged length of hospital stay and high 30-day mortality
Cooperativity Dominates the Genomic Organization of p53-Response Elements: A Mechanistic View
p53-response elements (p53-REs) are organized as two repeats of a palindromic DNA segment spaced by 0 to 20 base pairs (bp). Several experiments indicate that in the vast majority of the human p53-REs there are no spacers between the two repeats; those with spacers, particularly with sizes beyond two nucleotides, are rare. This raises the question of what it indicates about the factors determining the p53-RE genomic organization. Clearly, given the double helical DNA conformation, the orientation of two p53 core domain dimers with respect to each other will vary depending on the spacer size: a small spacer of 0 to 2 bps will lead to the closest p53 dimer-dimer orientation; a 10-bp spacer will locate the p53 dimers on the same DNA face but necessitate DNA looping; while a 5-bp spacer will position the p53 dimers on opposite DNA faces. Here, via conformational analysis we show that when there are 0–2 bp spacers, p53-DNA binding is cooperative; however, cooperativity is greatly diminished when there are spacers with sizes beyond 2 bp. Cooperative binding is broadly recognized to be crucial for biological processes, including transcriptional regulation. Our results clearly indicate that cooperativity of the p53-DNA association dominates the genomic organization of the p53-REs, raising questions of the structural organization and functional roles of p53-REs with larger spacers. We further propose that a dynamic landscape scenario of p53 and p53-REs can better explain the selectivity of the degenerate p53-REs. Our conclusions bear on the evolutionary preference of the p53-RE organization and as such, are expected to have broad implications to other multimeric transcription factor response element organization
Utjecaj uvjeta uzgoja i dodatka soli na sastav eteričnog ulja slatkog mažurana (Origanum majorana) iz Tunisa
O. majorana shoots were investigated for their essential oil (EO) composition. Two experiments were carried out; the first on hydroponic medium in a culture chamber and the second on inert sand in a greenhouse for 20 days. Plants were cultivated for 17 days in hydroponic medium supplemented with NaCl 100 mmol L1. The results showed that the O. majorana hydroponic medium offered higher essential oil yield than that from the greenhouse. The latter increased significantly in yield (by 50 %) under saline constraint while it did not change in the culture chamber. Under greenhouse conditions and in the absence of salt treatment, the major constituents were terpinene-4-ol and trans-sabinene hydrate. However, in the culture chamber, the major volatile components were cis-sabinene hydrate and terpinene-4-ol. In the presence of NaCl, new compounds appeared, such as eicosane, spathulenol, eugenol, and phenol. In addition, in the greenhouse, with or without salt, a very important change of trans-sabinene hydrate concentration in EO occurred, whereas in the culture chamber change appeared in cis-sabinene hydrate content.U radu je opisano ispitivanje sastava eteričnog ulja izdanaka biljke O. majorana. Provedena su dva eksperimenta: prvi na hidroponom mediju u komorama za uzgoj, a drugi na inertnom pijesku u stakleniku tijekom 20 dana. Biljke su uzgajane 17 dana u hidroponom mediju u koji je dodan NaCl 100 mmol L1. Rezultati ukazuju na to da hidroponi medij O. majorana osigurava veće prinose eteričnog ulja nego staklenik. U stakleniku se prinos ulja značajno povećao dodavanjem 50 % soli dok u uzgoju u uzgojnoj komori nije bilo promjene. U uvjetima u stakleniku i u odsutnosti soli, najvažniji sastojci ulja bili su terpinen-4-ol i trans-sabinen hidrat, dok su u uvjetima uzgojne komore najvažnije hlapljive komponente bile cis-sabinen hidrat i terpinen-4-ol. U prisutnosti NaCl-a, pojavili su se novi sastojci, kao što su eikozan, spatulenol, eugenol i fenol. Dodatno je uz stakleničke uvjete, sa i bez soli, došlo do važne promjene u količini trans-sabinen hidrata u eteričnom ulju, dok se u komorama promijenio sadržaj cis-sabinen hidrata
Awareness Is Not Enough: Pitfalls of Learning Analytics Dashboards in the Educational Practice
Presentation at 12th European Conference on Technology enhanced learning (EC-TEL 2017
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