Penning-Trap Mass Measurement of Helium-4.

Light-ion trap (LIONTRAP), a high-precision Penning-trap mass spectrometer, was used to determine the atomic mass of ^{4}He. Here, we report a 12 parts-per-trillion measurement of the mass of a ^{4}He^{2+} ion, m(^{4}He^{2+})=4.001 506 179 651(48) u. From this, the atomic mass of the neutral atom can be determined without loss of precision: m(^{4}He)=4.002 603 254 653(48) u. This result is slightly more precise than the current CODATA18 literature value but deviates by 6.6 standard deviations.

Medical Pedagogy in the Time of COVID-19.

Medical teaching is about giving a student a collaborative experience of the art and skill of the practice of medicine. This is acquired through authentic patient experiences. A clinical teacher uses clinical lectures, simulations, lab sessions, small group interactions, cadaver dissection and technical classes (eg: ultrasound) to create a complete clinical immersion experience. For this we use both the in-patient and out-patient facilities.

Effect of dimerized melittin on gastric cancer cells and antibacterial activity.

Melittin is the peptide toxin found in bee venom and is effective against cancer cells. To enhance its activity, a branched dimeric form of melittin was designed. The monomeric form of the peptide was more cytotoxic against gastric cancer cells at low concentrations (1-5 µM) than the dimer form, while the cytotoxic effect was comparable at higher concentrations (10 µM). Confocal microscopy showed that both the monomer and dimer forms of melittin with fluorescent label at the C terminus penetrated the cytoplasm and localized at the cell nucleus and disrupted the cell membrane. The results indicated that both peptides localized in the nucleus and no significant difference in penetration was observed between monomer and dimer of melittin. Although the C and N termini are important for melittin activity, using C terminus for dimerization of the peptide resulted in similar activity for the monomer and dimer against bacteria and gastric cancer cells.

Inhibition of Staphylococcus aureus by crude and fractionated extract from lactic acid bacteria.

Increasing levels of antibiotic resistance by Staphylococcus aureus have posed a need to search for non-antibiotic alternatives. This study aimed to assess the inhibitory effects of crude and fractionated cell-free supernatants (CFS) of locally isolated lactic acid bacteria (LAB) against a clinical strain of S. aureus. A total of 42 LAB strains were isolated and identified from fresh vegetables, fresh fruits and fermented products prior to evaluation of inhibitory activities. CFS of LAB strains exhibiting a stronger inhibitive effect against S. aureus were fractionated into crude protein, polysaccharide and lipid fractions. Crude protein fractions showed greater inhibition against S. aureus compared to polysaccharide and lipid fractions, with a more prevalent effect from Lactobacillus plantarum 8513 and L. plantarum BT8513. Crude protein, polysaccharide and lipid fractions were also characterised with glycine, mannose and oleic acid being detected as the major component of each fraction, respectively. Scanning electron microscopy revealed roughed and wrinkled membrane morphology of S. aureus upon treatment with crude protein fractions of LAB, suggesting an inhibitory effect via the destruction of cellular membrane. This research illustrated the potential application of fractionated extracts from LAB to inhibit S. aureus for use in the food and health industry.

Evaluation of the effect of Cassia surattensis Burm. f., flower methanolic extract on the growth and morphology of Aspergillus niger.

BACKGROUND AND AIM: Cassia (C.) surattensis Burm. f. (Leguminosae), a medicinal herb native to tropical equatorial Asia, was commonly used in folk medicine to treat various diseases. The aim of the present study is to investigate the effects of methanolic flower extract of C. surattensis against Aspergillus (A.) niger. MATERIALS AND METHODS: Antifungal activity of C. surattensis flower extract was studied by using agar disc diffusion method, broth dilution method, percentage of hyphal growth inhibition and scanning electron microscopy (SEM) observation. RESULTS: The extract exhibited good antifungal activity with zone of inhibition 15 mm and minimum inhibitory concentration (MIC) 6.25 mg/ml. The flower extract exhibited considerable antifungal activity against A. niger with a IC50 of 2.49 mg/ml on the hyphal growth. In scanning electron microscopy (SEM) squashed, collapsed, empty and deformation of hyphae were the major changes observed. Shrunken conidiophores were the obvious alteration on the spores. Morphological alterations observed on A. niger caused by the flower extract could be the contribution of chemical compounds present in the Cassia flower. Phytochemical screening reveals the presence of carbohydrate, tannins, saponins and phenols in the extract. The amount of tannin, total phenolics and flavonoids were estimated to be 55.14 ± 3.11 mg/g, 349.87 ± 5.41 mg/g gallic acid equivalent and 89.64 ± 3.21 mg/g catechin equivalent respectively. CONCLUSIONS: C. surattensis flower extract potently inhibited the growth of A. niger and are, therefore, excellent candidates for use as the lead compounds for the development of novel antifungal agents.

Anti-Candida activity and brine shrimp toxicity assay of Ganoderma boninense.

OBJECTIVES: Ganoderma (G.) boninense is a white rot fungus, which can be found in the palm oil tree. Several studies have shown that G. boninense has antimicrobial and antagonistic properties. However, there is limited information reported on antifungal properties especially on Candida (C) albicans. Hence, this study was conducted to determine the anti-Candida activity of G. boninense against C albicans. MATERIALS AND METHODS: Crude methanolic extracts of G. boninense was obtained by maceration method with 70% methanol. Anti-Candida test was carried out using disc diffusion assay, broth dilution method, time killing profile and brine shrimp toxicity assay. RESULTS AND CONCLUSIONS: Anti-Candida activity indicated that the mean zone of inhibition was 12.5 +/- 0.6 mm. The MIC value for C. albicans found to be 3.125 mg/ml. The result from time-killing profile showed that the growth of C albicans was inhibited hence decreases its exponential phase. For brine shrimp toxicity assay, the LC50 value was 3.59 mg/ml which proved that the extract of G. boninense is not toxic.

SU-E-T-231: Comparison of Beam Characteristics of Small Field 6 MeV Electrons as Replacement for Superficial X Ray Beam.

PURPOSE: To compare beam characteristics of superficial X-rays with 6 MeV Electrons for the purpose of replacing superficial treatments with electron fields for skin lesions. METHODS: Electron beam cutouts were made with 12mm thickness cerrobend in diameters 2-5 cm to match superficial X-ray machine cones. Central axis depth doses and profiles were generated using 0.007 cc Exradin A-16 ion chamber, in PTW water phantom at 1mm steps, at 96 and 100cm SSD for electron beams, and at 15cm SSD for superficial X-rays. From the beam data, radiation penumbra 90-10%, 90% profile width, peripheral dose and percentage depth dose were obtained for comparison. RESULTS: The 90-10% radiation penumbra was ranging 7.4-13.7 mm, 12.6-17.6 mm for 6 MeV electrons at 96 and 100cm SSD respectively, and 4.2-11.4 mm for 2-5 cm superficial X-ray cones. For 90% treatment width, a margin ranging 5-7 mm, 6-9 mm is needed around the periphery of target for 6 MeV Electrons at 96 and 100cm SSD respectively, and 2-3 mm for superficial X-ray cones. For 96cm SSD, the peripheral dose from the geometrical field edge were 3.9% at 1cm and 0.5% at 2cm. It was 2.6% at 1cm and 0.7% at 2cm for 100cm SSD. For superficial, it was 6.2%, 7.5%, 9.1% at 1cm, and 3.4%, 4.3%, 5.6% at 2cm for 100 kV, 120 kV and 150 kV respectively. The electron surface dose was below 90%. CONCLUSION: 6 MeV Electron beam shows high superiority with rapid fall off of dose beyond target with lower peripheral dose compared to superficial X-rays. However, the electrons need higher margin around the target and also need appropriate bolus thickness to increase skin dose. The dose at depth beyond 2cm makes very significant advantage using electrons compared to superficial X-rays.

In vitro and in situ antiyeast activity of Gracilaria changii methanol extract against Candida albicans.

BACKGROUND AND OBJECTIVES: The Gracilaria (G.) sp are widely used in the traditional medicine in Malaysia. The methanol extract of Gracilaria changii B.M. Xia & I.A. Abbott (Gracilariaciae) was evaluated for antiyeast activity against Candida albicans (Berkhout). MATERIALS AND METHODS: The antiyeast activities were studied by using disc diffusion method and broth dilution method. The effect of the extract on the growth profile of the yeast was also examined via time-kill assay. In addition, the in situ antiyeast activity was studied by microscopic observations using scanning electron microscopy (SEM), transmission electron microscopy (TEM) to determine the major alterations in the microstructure of Candida (C.) albicans. RESULTS AND DISCUSSION: The extract showed a favourable antimicrobial activity against C albicans with a minimum inhibitory concentration (MIC) value of 1.56 mg/mL. The main abnormalities noted from the SEM and TEM studies were the internal shrinkage of cell, disorganization within the cell cytoplasm and complete collapse of the yeast cells after 36 h of exposure to the extract. The time-kill assay suggested that the G. changii extract significantly inhibited C. albicans growth and it also exhibited prolonged antiyeast activity against the C albicans. CONCLUSION: The extract has shown in vitro fungicidal properties against C. albicans and should be investigated for its therapeutic potential.

Anti-Candida albicans biofilm activity by Cassia spectabilis standardized methanol extract: an ultrastructural study.

BACKGROUND AND OBJECTIVE: Candida (C.) albicans infection in its biofilm mode of growth has taken centre point with the increasing recognition of its role in human infections due to the development of resistance to the commonly used antibiotic or phenotypic adaptation within the biofilm. Hence, in this study the inhibitory effect of methanol extract of Cassia (C.) spectabilis leaves was evaluated against biofilm forming C. albicans. MATERIALS AND METHODS: Anti-yeast activities were carried out using disc diffusion assay and broth dilution method against biofilm forming C. albicans. C. spectabilis leaves extract was assessed using XTT (2,3-bis [2-Methoxy-4-nitro-5-sulphophenyl]-2H-tetrazolium-5-carboxanilide) reduction assay for biofilm quantification with positive control fluconazole. Scanning electron microscopic (SEM) and confocal scanning laser microscopy (CLSM) analysis further revealed reduction in C. albicans biofilm by C. spectabilis leaves extract. RESULTS AND DISCUSSION: The methanol extract of C. spectabilis showed a favorable antiyeast activity against C. albicans with MIC (Minimum Inhibitory Concentration) value of 6.25 mg/ml. Fluconazole and leaves extract showed 95.4% and 96.9% biofilm reduction respectively. The main changes observed under scanning electron microscopy after C. spectabilis leaves extract treatment were cellular damage and disruption in biofilms of C. albicans. The ultrastructural changes visualized by SEM were further confirmed using CLSM study. CONCLUSIONS: The results from this research conclusively exhibit the in vitro anti-biofilm potential of C. spectabilis leaves extract against Candida biofilm.

Effects of Vernonia cinerea less methanol extract on growth and morphogenesis of Candida albicans.

BACKGROUND AND OBJECTIVES: Vernonia (V.) cinerea Less (Asteraceae) have many therapeutic uses in the practice of traditional medicine. The methanol extract of V cinerea, was screened for antiyeast activity against pathogenic yeast Candida albicans. MATERIALS AND METHODS: The antimicrobial activities were studied by using disc diffusion method and broth dilution method. The effect of the extract on the growth profile of the yeast was also examined via time-kill assay. In addition to the fungicidal effects study, microscopic observations using Scanning (SEM) electron microscopy, Transmission (TEM) electron microscopy and light microscopy (LM) were done to determine the major alterations in the microstructure of Candida (C) albicans. RESULTS AND DISCUSSION: The extract showed a favorable antimicrobial activity against C. albicans with a minimum inhibitory concentration (MIC) value of 1.56 mg/mL. Time-kill assay suggested that Vernonia cinerea extract had completely inhibited Candida albicans growth and also exhibited prolonged antiyeast activity. The main abnormalities notes from these microscopic observations were the alterations in morphology and complete collapse of the yeast cells after 36 h of exposure to the extract. CONCLUSION: The extract of Vernonia cinerea may be an effective agent to treat the Candida albicans infection.

In vitro and in vivo anticandidal activity of Swietenia mahogani methanolic seed extract.

Swietenia mahogani crude methanolic (SMCM) seed extract was investigated for the antifungal activity against Candida albicans which has not been evaluated previously. The antifungal activity was evaluated against C. albicans via disk diffusion, minimum inhibition concentration (MIC), scanning electron microscope (SEM), transmission electron microscope (TEM) and time killing profile. The MIC value of SMCM seed extract is 12.5 mg/ml. The SEM and TEM findings showed there is morphological changes and cytological destruction of C. albicans at the MIC value. Animal model was used to evaluate the in vivo antifungal activity of SMCM seed extract. The colony forming unit (CFU) were calculated per gram of kidney sample and per ml of blood sample respectively for control, curative and ketaconazole treated groups. There was significant reduction for the CFU/ml of blood and CFU/g of kidney. This indicated that the extract was observed to be effective against C. albicans in vitro and in vivo conditions.

Antimicrobial drug resistance of Staphylococcus aureus in dairy products.

OBJECTIVE: To evaluate the prevalence of multidrug resistant Staphylococcus aureus (S. aureus) in dairy products. METHODS: Isolation and identification of S. aureus were performed in 3 dairy-based food products. The isolates were tested for their susceptibility to 5 different common antimicrobial drugs. RESULTS: Of 50 samples examined, 5 (10%) were contaminated with S. aureus. Subsequently, the 5 isolates were subjected to antimicrobial resistance pattern using five antibiotic discs (methicillin, vancomycin, kanamycin, chloramphenicol and tetracycline). Sample 29 showed resistance to methicillin and vancomycin. Sample 18 showed intermediate response to tetracycline. The other samples were susceptible to all the antibiotics tested. CONCLUSIONS: The results provide preliminary data on sources of food contamination which may act as vehicles for the transmission of antimicrobial-resistant Staphylococcus. Therefore, it enables us to develop preventive strategies to avoid the emergence of new strains of resistant S. aureus.

Optimal protein extraction methods from diverse sample types for protein profiling by using Two-Dimensional Electrophoresis (2DE).

There is a great diversity of protein samples types and origins, therefore the optimal procedure for each sample type must be determined empirically. In order to obtain a reproducible and complete sample presentation which view as many proteins as possible on the desired 2DE gel, it is critical to perform additional sample preparation steps to improve the quality of the final results, yet without selectively losing the proteins. To address this, we developed a general method that is suitable for diverse sample types based on phenolchloroform extraction method (represented by TRI reagent). This method was found to yield good results when used to analyze human breast cancer cell line (MCF-7), Vibrio cholerae, Cryptocaryon irritans cyst and liver abscess fat tissue. These types represent cell line, bacteria, parasite cyst and pus respectively. For each type of samples, several attempts were made to methodically compare protein isolation methods using TRI-reagent Kit, EasyBlue Kit, PRO-PREP™ Protein Extraction Solution and lysis buffer. The most useful protocol allows the extraction and separation of a wide diversity of protein samples that is reproducible among repeated experiments. Our results demonstrated that the modified TRI-reagent Kit had the highest protein yield as well as the greatest number of total proteins spots count for all type of samples. Distinctive differences in spot patterns were also observed in the 2DE gel of different extraction methods used for each type of sample.

Extraction, isolation and characterization of bioactive compounds from plants' extracts.

Natural products from medicinal plants, either as pure compounds or as standardized extracts, provide unlimited opportunities for new drug leads because of the unmatched availability of chemical diversity. Due to an increasing demand for chemical diversity in screening programs, seeking therapeutic drugs from natural products, interest particularly in edible plants has grown throughout the world. Botanicals and herbal preparations for medicinal usage contain various types of bioactive compounds. The focus of this paper is on the analytical methodologies, which include the extraction, isolation and characterization of active ingredients in botanicals and herbal preparations. The common problems and key challenges in the extraction, isolation and characterization of active ingredients in botanicals and herbal preparations are discussed. As extraction is the most important step in the analysis of constituents present in botanicals and herbal preparations, the strengths and weaknesses of different extraction techniques are discussed. The analysis of bioactive compounds present in the plant extracts involving the applications of common phytochemical screening assays, chromatographic techniques such as HPLC and, TLC as well as non-chromatographic techniques such as immunoassay and Fourier Transform Infra Red (FTIR) are discussed.

Optimal protein extraction methods from diverse sample types for protein profiling by using Two-Dimensional Electrophoresis (2DE)

There is a great diversity of protein samples types and origins, therefore the optimal procedure for each sample type must be determined empirically. In order to obtain a reproducible and complete sample presentation which view as many proteins as possible on the desired 2DE gel, it is critical to perform additional sample preparation steps to improve the quality of the final results, yet without selectively losing the proteins. To address this, we developed a general method that is suitable for diverse sample types based on phenolchloroform extraction method (represented by TRI reagent). This method was found to yield good results when used to analyze human breast cancer cell line (MCF-7), Vibrio cholerae, Cryptocaryon irritans cyst and liver abscess fat tissue. These types represent cell line, bacteria, parasite cyst and pus respectively. For each type of samples, several attempts were made to methodically compare protein isolation methods using TRI-reagent Kit, EasyBlue Kit, PRO-PREPTM Protein Extraction Solution and lysis buffer. The most useful protocol allows the extraction and separation of a wide diversity of protein samples that is reproducible among repeated experiments. Our results demonstrated that the modified TRI-reagent Kit had the highest protein yield as well as the greatest number of total proteins spots count for all type of samples. Distinctive differences in spot patterns were also observed in the 2DE gel of different extraction methods used for each type of sample.

Quantum dot capped magnetite nanorings as high performance nanoprobe for multiphoton fluorescence and magnetic resonance imaging.

In the present study, quantum dot (QD) capped magnetite nanorings (NRs) with a high luminescence and magnetic vortex core have been successfully developed as a new class of magnetic-fluorescent nanoprobe. Through electrostatic interaction, cationic polyethylenimine (PEI) capped QD have been firmly graft into negatively charged magnetite NRs modified with citric acid on the surface. The obtained biocompatible multicolor QD capped magnetite NRs exhibit a much stronger magnetic resonance (MR) T2* effect where the r2* relaxivity and r2*/r1 ratio are 4 times and 110 times respectively larger than those of a commercial superparamagnetic iron oxide. The multiphoton fluorescence imaging and cell uptake of QD capped magnetite NRs are also demonstrated using MGH bladder cancer cells. In particular, these QD capped magnetite NRs can escape from endosomes and be released into the cytoplasm. The obtained results from these exploratory experiments suggest that the cell-penetrating QD capped magnetite NRs could be an excellent dual-modality nanoprobe for intracellular imaging and therapeutic applications. This work has shown great potential of the magnetic vortex core based multifunctional nanoparticle as a high performance nanoprobe for biomedical applications.

Toxicity study of Vernonia cinerea.

The methanol extract of Vernonia cinerea Less (Asteraceae), which exhibited antimicrobial activity, was tested for toxicity. In an acute toxicity study using mice, the median lethal dose (LD(50)) of the extract was greater than 2000 mg/kg, and we found no pathological changes in macroscopic examination by necropsy of mice treated with extract. As well as the oral acute toxicity study, the brine shrimp lethality test was also done. Brine shrimp test LC(50) values were 3.87 mg/mL (6 h) and 2.72 mg/mL (24 h), exhibiting no significant toxicity result. In conclusion, the methanol extract of V. cinerea did not produce toxic effects in mice and brine shrimp.

Effects of Stenochlaena palustris Leaf Extract on Growth and Morphogenesis of Food Borne Pathogen, Aspergillus niger.

Some synthetic preservatives have become controversial because they have been proven to cause health problems. These increased health concerns have led consumers to prefer food preservatives based on natural products. Hence, Stenochlaena palustris leaf extract was used in this study to evaluate the antifungal activity against food borne pathogen, Aspergillus niger. The value of minimum inhibitory concentration and minimum fungicidal concentration of leaf extract for this fungus grown on Potato Dextrose Agar medium was 50 mg/ml. IC50 value for the hyphal growth of A. niger was at a concentration of 17.41 mg/ml. Morphology changes of A. niger treated with the fern leaf extract was observed through scanning electron microscope. The thread-like and elongated hyphae cell wall was disrupted, with some appearing flattened and others being broken. Currently, there is growing interest in using natural food preservatives such as medicinal plant extracts for preserving foods to reduce outbreaks of foodborne pathogenic microorganisms. Hence, S. palustris appears to have promise as a safe alternative natural product-based food preservative for future generations.

Effects of Clitoria ternatea leaf extract on growth and morphogenesis of Aspergillus niger.

Clitoria ternatea is known for its antimicrobial activity but the antifungal effects of leaf extract on growth and morphogenesis of Aspergillus niger have not been observed. The extract showed a favorable antifungal activity against A. niger with a minimum inhibition concentration 0.8 mg/mL and minimum fungicidal concentration 1.6 mg/mL, respectively. The leaf extract exhibited considerable antifungal activity against filamentous fungi in a dose-dependent manner with 0.4 mg/mL IC50 value on hyphal growth of A. niger. The main changes observed under scanning electron microscopy after C. ternatea extract treatment were loss of cytoplasm in fungal hyphae and the hyphal wall and its diameter became markedly thinner, distorted, and resulted in cell wall disruption. In addition, conidiophore alterations were also observed when A. niger was treated with C. ternatea leaf extract.