Sorry for blogging so late. First on the list is due dates. Dr Hartley indicated that the Evolution homework is due on or before December 8th by email or digital box. The grant proposal is due tomorrow December 3rd in class. Please bring 3 copies of your proposal to class, two of which cannot have names. On final day (12/8/2009) bring your grant reviews. Also on tomorrow Dr. Hartley will bring a list indicating the number of blogs each person has done so far…. REMEMBER: YOU HAVE UNTIL DECEMBER 8TH (Finals day) TO GET YOUR 8 BLOGS IN!!!
This coming up class we will have a group assignment. Please bring all of your notes from class. The assignment will be a way to recap the different concepts we have learned. DO NOT MISS CLASS THE ASSIGNMENT WILL COUNT FOR A GRADE!!!
We started lecture by reviewing a few terms and concepts. They are listed below:
- Evolution - Evolution in simple terms is change in gene frequency over time. In order for it to occur there has to be mutation, selection (natural and artificial), gene Flow/migration, and genetic drift.
We also talked about what needs to happen in order for natural selection to occur. We need variation, heritability, selection, and time.
- Evolution of virulence- under this topic we talked discussed the definition of virulence which is, a parasite mediated morbidity and mortality. Virulence can either be avirulent where the symptoms of the host does not directly affect the parasite. Asymptomatic the symptoms do directly affect the parasite. Asymptomatic is usually fast killing.
One model for evolution of virulence we talked about was the Trade-Off model. Ying explained, if pathogen is more virulent it would kill the host to quickly. So the pathogen cannot be too virulent, but it has to be virulent enough to continue to the chain of infection. It is not in the best interest of a pathogen to be too virulent.
Effects of vaccines on pathogen evolution- In regards to this topic we talked about how even if a pathogen vaccines can alter the immune pressures experienced by the pathogen. Sometimes the pathogen can evolve a new way to be virulent. Dr. Hartley clarified the definition of vaccine breakthrough. It is when a person has received a vaccine but still becomes sick with the disease the vaccine was to prevent.
After review we continued began talking about evolution of antimicrobial resistance. She discussed nosocomial infections, which are hospital- acquired infections that are a major public health problem. Out of about 200,000 people many people are dying of these kind of infections. The numbers estimated are 17,000 AIDS/HIV, 37,000 flu, and 40,000 breast cancer. WHO (World Health Organization) estimated that 8.7% of hospital visits will result in these types of infections. This is because there are many anti-viral resistent strains of bacteria in hospitals. Because evolution pressure is different in hospitals it is important that people should get antibiotics unless needed because it will increase the evolution of infection causing more resistant strains.
On the slide listed history of antibiotic resistance with the list of antibiotics, Dr. Hartley indicated that the first Vancomycin listed is the correct one. This particular drug we discussed is usually for the last resort. It has to be administered intravenously because it cannot be absorbed orally. It is used when all other antibiotics have failed. Looking up more research on the drug some of the side effects are hearing lost and kidney damaged when tested in the 1950′s. Recent studies have shown that vancomycin can induce platelet-reactive antibodies which leads to severe thrombocytopenia ( platelets in the blood) and bleeding with florid petechial hemorrhages (small spots on the body), ecchymoses ( bruises), and wet purpura. http://en.wikipedia.org/wiki/Vancomycin
Dr. Hartley also explained how pathogens become antibiotic- resistant. What she is explained is that after the antibiotic is administered the first time the pathogen dies off leaving only a few that were able to resist drug. Over time more of the pathogens become antiobiotic-resistant. We discussed what mechanisms there are that cause antibiotic resistant phenotypes. The mechanisms are: Point mutations, homologous recombination, and heterologous recombination. These phenotypes arise from natural soils, agriculture use, and hospital use. In regards to agricultural use, the slide indicates that the phenotypes are passed on because the farmer works in the farm and gets sick and goes to the hospital passing it on to whoever he comes in contact with there. If he gives it to people within hospital when those people leave they are then passing it on to whoever they come in contact with too. Then food from the farm makes it to grocery stores and restaurants. People then get the food from stores and food places getting them sick…
Dr. Hartley wanted me to look up what patients with MRSA are treated with. I checked the blog and it looked like that was answered for me. We did learn that subtherapeutic are lower doses of a vaccine that does no kill bacteria, and therapeutic are doses of a vaccine that are used to kill bacteria. There are higher selection pressure in hospitals because they have weaker immune systems and can get infected easily. When the staff get infected because of high turnover rate it is passed on to the neighborhood easily.
Lastly, we talked about the different ways to prevent or treat resistance. Mixing and cycling are two different ways it can be treated or prevented. Mixing is when different antibiotics are administered to each person so that they are never introduced to the patients near them. Mixing is within space. Coupling is when a hospital administered a specific antibiotic to all the patients and then over time switch the antibiotic. The only problem is the lobster trap could keep cycling from working. The lobster trap is a genotype easy to reach by selection in one direction, but difficult to leave when selection goes in the other direction ( Hartley 2009). Strategies that c an be used are: 1)Predicting resistance evolution 2) narrowing spectrum antibiotics 3) Bacteriocins 4) Ecological modeling
And class is over…. remember to be in class thursday…
Thank you for the break down, and for re-writing the definitions. I think this will help on the evolution assignment we have coming up. What I found interesting were the statistics for AIDS/HIV vs. infection and flu. It really puts things into perspective.
I think that we never really think how much people pass on germs and other bacteria just doing their normal daily duties (work, school, etc.). We like to think of hospitals as being very clean. But I guess the people that work there too (no matter how much they try to prevent it) keep the chain of infection going. I think the best part of the evolution lecture was the part we discussed the antio-biotic resistant bacterias.
While working in a hospital setting you see a lot of people who do not follow protocols for washing hands and wearing gloves. It would surprise you how many don’t. I think that can contribute to the fact that there is a lot of germs and bacteria spread throughout the hospital. I agree that the best part of the lecture was about the antibiotic resistant bacteria. It is amazing how fast bacteria becomes resistant to medications. Penicillin only took about a year or two to become resistant after first being introduced.
Talking about due dates for ceratin assinments…….as John and I were finishing up our Grant Proposal last night, we noticed that in the instructions, the max pages for BIO4053 is 10 and for BIO 5053 is 12. Then we looked over the grading rubric and on there it says 8 pages for 4053 and still 12 pages for 5053. We were wondering if anyone else noticed…..maybe I’ll bring it up in class, because we thought the 5053 students page limit was 15. I don’t know what to say about the 4053 page limit…..
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I did notice that after writing the entire paper. I think the grant proposal intructions and rubric did not match do it caused a little confusion. So I’m glad that you also saw the change as well.
I think it was supposed to be 10 pages instead of 8. I could be wrong though.
wow…..i meant to say certain assignments, not ceratin assinments, in my last comment!
I have been told by two different people that they have bitten into a maggot as they were eating a Hershey’s kiss. Now, these were NOT the ones that Dr. Hartley gave us. I guess if the package is opened long enough then this can happen, since kisses usually have a little chocolate exposed on the top that aren’t fully covered by the foil. Can you imagine all the other stuff that can possibly get into them or other foods that are packaged the same way? So tip of the day is: Do not eat candy that has been opened for a while, unless they are completely sealed.
Wow, that is disgusting! I have also noticed that the kiss packaging doesn’t cover all of the top, so I can see how they could be contaminated. Wouldn’t they have noticed a maggot though?
I think that is really nasty. Can you only imagine the things that we may be eating. We might be eating all types of bugs. You know all of the rats and roaches that crawl on food when they are being shipped to the stores. I’ve heard of people getting roach eggs in their jaws and all kinds of other stuff. Be careful!!!!
Wow! That is disgusting! I have heard stories about certain fast food places and people eating bugs. Ew! I wonder how long it took for the maggots to get in there and grow? I have seen a fact though that throughout your lifetime you will have swallowed 8 spiders during your sleep. That seems crazy to me.
I would also like to comment on the in class activity we did on the 3rd. It made me realize that there was a lot of material that we covered throughout the semester. It was very helpful to have this review day to refresh my memory of what we did and what was important.
I agree, it really did put the entire class into perspective. I was a bit surprised about the amount of information we covered, it certainly did not seem so until we had everything laid out in outlines.
The outlines we did for each of the topics we discussed throughout the semester was a useful synthesis of all the class lectures. The structure of the class was very organized and all information could be related to each other. I hope that we are able to do the question/puzzle game in class on Thursday if that will help any more with knowledge retention.
I was able to read one of the grad student’s grant proposal that he will be presenting on Thursday. I wish all grad students the best of luck!
That was a really good blog. It helped clarify definitions for the evolution assignment. Also thank you for posting the assignment due dates. I was wondering when everything was due.
Something that I have found interesting the entire semester (and yes, I do realize that this is a DISEASE class) is how we tend to look at certain organisms like MRSA and only see the bad things they do to us and not the good. Organisms like MRSA ususally do no harm to us and actually help us out. I’ve read some studies about how if you are missing certain organisms from your body, you can get diseases like skin conditions and even GI diseases. These organisms are no different than us, they just want a good place to live where it is warm and there are plenty of nutrients for them. I think that even in a class like this, this should be brought up more .
This blog says the final takes place on December 8th, Tuesday. But the updated exam schedule places our final exam time for December 10th.
See you all Thursday.
This is right?