A graduate student was assaying LD50 (lethal dose 50%) of two temperature-sensitiveFrancisella tularensis strains in HeLa cells (human cell line). Both strains can infect humansand cause fatal tularemia if untreated, but it is difficult to obtain LD50 values in humansubjects. The data below shows LD50 (lethal dose 50%) values of the strains in human cellculture. Can you predict the more virulent strain of the two human pathogens?Francisella tularensis strain A: LD50 @ 20°C= 100; LD50 @ 37°C= 1000Francisella tularensis strain B: LD50 @ 20°C= 1000 LD 50 @ 37°C= 100O It is not possible to determine the virulence of the two strains as human pathogens from theprovided dataStrain A and strain B are equally virulent as human pathogens, as they average out in virulence.O Strain A is more virulent than strain A as a human pathogen.O Strain B is more virulent than strain A as a human pathogen.

let's break it down further: 1. **Understanding LD50**: LD50 (Lethal Dose 50) is a measure of the…

Answered: A graduate student was assaying LD50…

Human Anatomy & Physiology (11th Edition)

11th Edition

ISBN:9780134580999

Author:Elaine N. Marieb, Katja N. Hoehn

Publisher:Elaine N. Marieb, Katja N. Hoehn

Chapter1: The Human Body: An Orientation

Section: Chapter Questions

Problem 1RQ: The correct sequence of levels forming the structural hierarchy is A. (a) organ, organ system,...

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A graduate student was assaying LD50 (lethal dose 50%) of two temperature-sensitive Francisella tularensis strains in HeLa cells (human cell line). Both strains can infect humans and cause fatal tularemia if untreated, but it is difficult to obtain LD50 values in human subjects. The data below shows LD50 (lethal dose 50%) values of the strains in human cell culture. Can you predict the more virulent strain of the two human pathogens? Francisella tularensis strain A: LD50 @ 20∘C= 100; LD50 @ 37∘C= 1000 Francisella tularensis strain B: LD50 @ 20∘C= 1000 LD50 @ 37∘C= 100 Group of answer choices It is not possible to determine the virulence of the two strains as human pathogens from the provided data Strain A and strain B are equally virulent as human pathogens, as they average out in virulence. Strain A is more virulent than strain A as a human pathogen. Strain B is more virulent than strain A as a human pathogen.
A COVID-19 test, which produce result in 10 minutes, has the following test characteristics. The test has a 95% sensitivity and a 95% specificity. The State of Massachusetts is in dilemma whether to test symptomatic individuals or the entire residents to decrease the spread of infection as depicted in the following two scenarios. Scenario A. The State of Massachusetts wants to administer the test on 40,000 individuals who will develop cough, fever and shortness of breath in the next 10 days to identify COVID-19 infected individuals and institute public health measures. The estimated prevalence of COVID-19 in this population is 750 per 1,000 population using a gold-standard test. Scenario B. The State of Massachusetts wants to administer the test to its entire COVID-19 uninfected population (6,750,000). The estimated prevalence of COVID-19 in this population is 5 per 1,000 population using a gold-standard test. Please help the State of Massachusetts by responding to the…
You have several different media onto which you inoculated eight strains of yeast (A-H). The media include a rich medium, an unsupplemented minimal medium, and minimal media each supplemented with one vitamin. Of the yeast strains, one is a prototroph and seven are auxotrophs for a vitamin. After overnight incubation, the following results were observed (tan patches represent growth): D plate 1 (A) B DE F GH plate 5 plate 4 plate 6 Which plate contains an unsupplemented minimal medium? [Select] Which plate contains a rich medium? [Select] plate 2 Which strain is a prototroph? [Select] Strain E is an auxotroph for niacin. Which plate reveals this specific auxotrophy? [ Select] plate 3 plate 7 One strain is an auxotroph for both choline and pantothenic acid. Which one is this most likely to be? [Select]
A nine-laboratory cooperative study was performed to evaluate quality control for susceptibility tests with 30-µg netilmicin disks [6]. Each laboratory tested three standard control strains on a different lot of Mueller-Hinton agar, with 150 tests performed per laboratory. For protocol control, each laboratory also performed 15 additional tests on eachof the control strains using the same lot of Mueller-Hinton agar across laboratories. The mean zone diameters for each of the nine laboratories are given in Table 6.11. *6.20 Provide a point and interval estimate (95% CI) for the interlaboratory standard deviation of mean zone diameters for each type of control strain, assuming each laboratory uses different media to perform the susceptibility tests. *6.21 Answer Problem 6.20 assuming each laboratory uses a common medium to perform the susceptibility tests. 6.22 Are there any advantages to using a common medium versus using different media for performing the susceptibility tests with…
A phagehunter performs a spot titer using standard techniques (3 ul of each dilution spotted to lawn) of a lysate obtained from an optimum webbed plate experiment. The phagehunter counts 8 plaques on the 10-7 dilution spot. Which of the following scenarios is the best choice for the phagehunter to do next? a.) The phagehunter has not achieved a high enough titer lysate to move forward with characterization experiments, so they should go back to the pick-a-plaque experiment. b.) The phagehunter has not achieved a high enough titer lysate to move forward with characterization experiments, so they should adopt a phage from direct isolation. c.) The phagehunter has not achieved a high enough titer lysate to move forward with characterization experiments, so they should try to make more optimum webbed plates. d.) The phagehunter has achieved a high enough titer lysate to move forward with characterization experiments.
Which of the following types of data produce curves similar in shape to the graph? Select all that apply 1.Bacterial growth in a culture 2.A normal distribution of height in a population of students 3.Exponential population growth 4.Haemoglobin binding of oxygen 5.Log transformations of drug dose curves 6.Osmotic fragility of red blood cells 7.A standard curve for an enyme assay
what are the volume dilution and dilution factor for bacteriophage A，B，C
Hi, I am working on qPCR quantification for specific bacteria. However, when the CT value achieve greater than 30, it always shown high CT value differences in my duplication no matter I repeat the same set of experiment for those samples with low quality. My question is, what makes this happening? The other question is, how many CT value differences is acceptable for duplication?
Prepare a dilution of phage from 1.5 x 1010 PFU/mL to 1.00 x 102 PFU/mL. Draw a dilution scheme to achieve this serial dilution considering the following: The volumes of each dilution should be 1.0mL. It is not advisable to perform any dilutions > 1/100. The first dilution in any titre determination of stock phage should use 10µl or less of stock.
Shown below is a set of cell culture plates for a plaque assay. The assay was performed by preparing dilutions of a virus stock with the dilution factor for each prepared dilution listed below the sample. 0.5 mls of each dilution was added to confluent (fully covered) monolayers of cells on each plate. The virus used for the assay had a titer of 2 x 1010 Plaque forming units (PFU) per ml. Only 1 set of the above plates would have a number of plaques on it that would be both easy to count and high enough to be statistically relevant. Which dilution set would it be and about how many plaques would there be on the plates of that dilution set.
Answer a,b and c
Streptococcus pneumoniae is a Gram-positive bacterium that colonizes the mucosal surface of the upper respiratory tract in humans. The presence of this bacterium in the nose and throat is widespread in the population, and in most people, colonization with Strep. pneumoniae is asymptomatic. The figure attached shows a comparison of in vitro growth curves of the wild-type strain of Strep. pneumoniae, as well as a Strep. pneumoniae mutant strain with a defect in one bacterial gene. The graph on the right shows the growth curve following addition of lysozyme during the logarithmic phase of bacterial growth. Which statement could account for the data in these graphs? Strain B is wild-type Strep. pneumoniae, and strain A is a mutant that cannot modify its peptidoglycan to be lysozyme-resistant. Strain B is wild-type Strep. pneumoniae, and strain A is a mutant that that expresses increased levels of LPS. Strain A is wild-type Strep. pneumoniae, and strain B is a mutant that cannot modify its…

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