Standardization of Herbal Drugs
Ravindra Kumar Pandey, Shiv Shankar Shukla, Amber Vyas, Vishal Jain, Parag Jain, Shailendra Saraf in Fingerprinting Analysis and Quality Control Methods of Herbal Medicines, 2018
Petri dishes of 9–10 cm in diameter are used for bacteria. To one dish, add a mixture of 1 mL of the pre-treated herbal material and about 15 mL of liquefied casein-soybean digest agar at a temperature not exceeding 45°C. Alternatively, spread the material on the surface of the solidified medium in a Petri dish. If necessary, dilute the material to obtain an expected colony count of not more than 300. Prepare at least two dishes using the same dilution, invert them, and incubate them at 30–35°C for 48–72 hours, unless a more reliable count is obtained in a shorter period of time. Count the number of colonies formed and calculate the results using the plate with the largest number of colonies, up to a maximum of 300. However, for determination of fungi, the casein-soybean digest agar is replaced with liquefied Sabouraud glucose agar and colonies should not number more than 100. Incubation should be performed at 20–25°C for 5 days, unless a more reliable count is obtained in a shorter period of time.
Dealing with the invisible
Brendan Curran in A Terrible Beauty is Born, 2020
Bacteria are ubiquitous, microscopically small, single-celled organisms, far too small to be seen without a microscope. Simple in structure, they reproduce by dividing in two to generate two identical cells. Some can divide every 20 minutes or so and thus, if sufficient nutrients are available (the record is about 9 minutes), can produce many billions of progeny overnight. If a number of bacteria are spread onto the surface of a nutrient jelly providing every food component they need to grow, each tiny bacterial cell will divide and divide to produce in a few hours a jumbled heap of cells in a colony which can be seen with the naked eye. The glass or plastic vessels used to grow bacteria are called Petri dishes after their inventor; microbiologists usually refer to them as ‘plates’, so spreading bacteria onto nutrient jelly is known as ‘plating’.
Immunoglobulins
Constantin A. Bona, Francisco A. Bonilla in Textbook of Immunology, 2019
In one application of this technique, agar is poured into a petri dish, and small wells are made. Antigen and antibody are placed in separate wells. If antigen-antibody reaction occurs, a line of precipitate forms where the reactants meet after diffusing into the gel. This is called an Outcherlony double diffusion reaction, named for the scientist who developed the method. By examining the patterns of precipitation in these reactions, one may determine whether two antigens share determinants, or whether two antibody preparations share specificities (Figure 4–18). Another variant of immunodiffusion is Immunoelectrophoresis. In this method, electrophoresis in one dimension is coupled with immunodiffusion in a perpendicular direction. With this technique, one may analyze much more complex mixtures of antigens and antibodies than with simple immunodiffusion (Figure 4–19).
Edaravone prevents high glucose-induced injury in retinal Müller cells through thioredoxin1 and the PGC-1α/NRF1/TFAM pathway
Published in Pharmaceutical Biology, 2021
Identification of Müller cells was performed after passaging the cells to the third generation. A cover glass was placed in a Petri dish. Next, the cells were digested and seeded on the cover glass. When the cells grew close to confluence, they were removed, washed with D-Hank’s solution, fixed with 4% paraformaldehyde (20 min) and treated with 0.1% Triton (15 min). The endogenous peroxidase was blocked by incubating the cells with 0.3% H2O2 for 20 min. After being blocked with normal goat serum (Beyotime, Shanghai, China) for 20 min, mouse anti-glial fibrillary acidic protein (GFAP, 1:200; Sigma-Aldrich, USA) or rabbit anti-glutamine synthetase (GS, 1:1,000; Sigma-Aldrich, USA) was added, while PBS (0.01 mol/L, pH 7.2) was added to the control group. The samples were incubated overnight at 4 °C and eluted with PBS. A goat anti-rat IgG-HRP was used as the secondary antibody (No. sc-2005, 1:3000; Santa Cruz Biotechnology, Santa Cruz, CA, USA, 1 h under room temperature). Upon elution with PBS, Hoechst was added to stain the nucleus. Cells were observed under a fluorescence inverted phase contrast microscope. The immunofluorescence staining showed that the majority of cells were GFAP- and GS-positive, indicating the purity of cells. The cell bodies and protrusions emitted red fluorescence, while the nucleus was Hoechst-positive with blue fluorescence, indicating that these cells were Müller cells (>90% of cells were identified as Müller cells).
Effect of particle morphology on performance of an electrostatic air–liquid interface cell exposure system for nanotoxicology studies
Published in Nanotoxicology, 2021
Ta-Chih Hsiao, Hsiao-Chi Chuang, Jing-Chi Lin, Tsun-Jen Cheng, Li-Ti Chou
The ESP-ALI exposure system used in this study comprised two cylinders of insulating materials. To avoid turbulent flow, the inside configuration of the upper cylinder was gradually expanded. A porous metal mesh was placed at the bottom of the upper cylinder; it dispersed the aerosol flow homogeneously and acted as the upper electrode for creating the electric field. A circular metal plate was placed atop the lower cylinder; it acted as the lower electrode (Figure 2). When operating the ESP-ALI, a negative DC voltage was applied to the collecting metal plate through a high-voltage power supply (BERTAN, series 230), and the porous metal mesh was grounded. A petri dish without culture medium was seated on the collecting metal plate. The ranges of applied voltage were set at 0-0.25 and 0-1.5 kV for ultrafine particles (NPs) and fine particles, respectively, and the uniform electric field was created between the porous metal mesh and collecting metal plate. The operational flow rate of 0.3, 0.6, and 1.5 lpm were tested. The experimental time was about 35 min and the range of particle concentration was from 104 to 109 particles/cm3 depending on operating conditions. Moreover, the variations of particle concentrations were less than 5% in the triple repeat measurements.
Surface properties of Enterococcus faecalis cells isolated from chicken hearts determine their low ability to form biofilms
Published in Biofouling, 2018
Jolanta Cieśla, Dagmara Stępień-Pyśniak, Agnieszka Nawrocka, Małgorzata Łukowska, Tomasz Hauschild, Andrzej Wernicki, Andrzej Bieganowski
Decimal dilutions of each bacterial suspension, with OD620 values of 3.6 × 10−2, 4.5 × 10−2, 5.2 × 10−2 and 5.9 × 10−2, were prepared in MH Broth (Oxoid). Then, 0.1 ml of each successive dilution of the suspensions, from 10−1 to 10−9, was placed on two Petri dishes containing Slanetz and Bartley medium (Biocorp). The material was distributed over the entire surface of the medium with a sterile, disposable bacteria spreader and then incubated at 37°C for 48 h. Petri dishes with 10–300 colonies were chosen to determine the bacterial count. The number of bacteria (N) per ml of each suspension was calculated according to the standard formula (CLSI 2008). The relationship between the optical density (OD620) and the number of bacterial cells is shown in Table 1.
Related Knowledge Centers
- Bacteria
- Bacteriologist
- Microscope
- Sterilization
- Agar
- Growth Medium
- Cell
- Microbiological Culture
- Culture Plate
- Microplate