My seminar subject: CXC chemokine ligand 4 (CXCL4) is a platelet-derived mediator of experimental liver fibrosis

My seminar presentation was finished, and I did very terribly. Anyway, here, I am going to talk about my seminar topic. As the title, my topic is "CXC chemokine ligand 4 (CXCL4) is a platelet-derived mediator of experimental liver fibrosis." First, I would like to introduce CXCL4 and liver fibrosis.

I think I would start with liver fibrosis. Liver fibrosis is cause by chronic liver disease and would lead to liver cirrhosis, end stage of liver failure, or even hepatocellular carcinoma. According to statistics of United States and Europe, the main reasons to cause liver fibrosis are HCV infection and steotohepatitis. The most important thing is that how does liver become fibrosis. The fact is that there are many myofibroblasts in the liver, and the main reason of liver fibrosis is that myofibroblasts secrete type I collagen which accumulates in the liver tissues and leads to liver fibrosis. However, there are many kinds of precursor of myofibroblast. They could be the cells derived from bone marrow, such as fibrocytes, or fibroblasts which are in the tissues originally, or sometimes hepatocytes could be changed into myofibroblast by stimulation of specific chemokines, but the main precursor is activated stellate cells. Hepatic stellate cells (HSCs) are in quiescent state in usual time, and they contain abundant lipid droplets which can store vitamin A. Quiescent HSCs could be activated by some conditions which could be liver injury, stimulation of lipopolysaccharide which is in the cell walls of gram-negative bacterium, or stimulation of specific chemokines. After HSCs being activated, they might have extra abilities such as proliferation, contractility, fibrogenesis, altered matrix degradation, chemotaxis, or releasing inflammatory signals. In addition, infiltration of immune cells could also lead to liver fibrosis.Fortunately, these mechanism of liver fibrosis could be regulated by some proteins like Timp-1, Tgf-beta, Mmp9, and IL-10.

Recently, the relation between coagulation cascade and liver fibrogenesis has been found. When coagulation cascade is activated, thrombins will be formed and platelets aggregation will be caused in the same time. If platelets aggregation occurs in liver, it will lead to HSCs proliferation. However, the key molecules of this mechanism are still unknown. One thing we know for sure is that platelets aggregation is caused by platelets activation. When tissues were injured, the collagen in the tissue may contact with blood stream, and the Von willebrand factor (vWF) in the blood stream would bind to collagen. The GPIIb-IIIa receptor on platelets membrane could bind to vWF and be activated after that. The activated platelets would release some coagulation factors, stored in platelets granules, to blood stream and caused clot formation, and one of the coagulation factors called fibrinogen could also bind to GPIIb-IIIa receptor. This would also make platelets to be activated and have the ability to link with each others and cause platelets aggregation. Interestingly, there are not only coagulation factors but also chemokines that are stored in platelet granules, and these chemokines would also be released to blood stream when platelets are activated. CXCL4 is an abundant chemokine in platelets. Actually, CXCL4 is both a chemokine and a coagulation factor. It is also called platelet factor 4 and it cause the formation of thrombus as a coagulation factor and it could activate monocytes as a chemokine. Recent studies show that CXCL4 mRNA was detected at elevated levels in the livers of patients with alcoholic liver disease ,and CXCL4 serum levels were elevated in patients with viral hepatitis. These evidences indirectly imply the potential of CXCL4 in liver disease. Therefore, the aim of this paper is to investigate the role of the platelet-derived CXCL4 in human experimental liver fibrosis.

In this experiment, both serum concentrations and intrahepatic CXCL4 mRNA were measured in patients with chronic liver disease and in mouse models. Electron microscopy and immunohistochemistry were utilized to determine platelet aggregation. Wild-type and CXCL4-/- mice were treated with CCl4 and thioacetamide (TAA) which are used to induce chronic liver damage. Intrahepatic infiltration of immune cells was investigated by fluorescence-activated cell sorting, and hepatic stellate cells were treated with recombinant murine CXCL4 in vitro. The results showed that CXCL4 serum levels and intrahepatic CXCL4 mRNA concentrations were increased in patients with advanced hepatitis C virus-induced liver fibrosis or nonalcoholic steatohepatisis. Platelets aggregation was obviously near collagen fibrils in the liver tissue. The treatment of CCl4 and TAA caused an increase of hepatic CXCL4 levels, platelet activation and aggregation in mice. Deletion of CXCL4 could reduce liver fibrosis significantly which is proved by histological and biochemical examinations. The results showed that the expression of fibrosis-related genes (tissue inhibitor of matrix metalloproteinase 1 [Timp-1], matrix metalloproteinase 9 [Mmp9], transforming growth factor beta [Tgf-β], interleukin 10 [IL-10]) were changed significantly in CXCL4-/- mice. In addition, infiltration of immune cells (neutrophils and CD8-positive T cells) into the liver was decreased in CXCL4-/- mice. In vitro results showed that hepatic stellate cells were activated after treating recombinant murine CXCL4 and showed the abilities of proliferation, chemotaxis, and chemokine expression.

In conclusion, when liver injury occur, platelets could be recruited to the injured site and be activated. Then activated platelets secrete CXCL4 which activates quiescent HSCs, and activated HSCs start to proliferate. This might cause the increasing of myofibroblasts since activated HSCs are the main precursor cells of myofibroblasts. Thus, increasing of myofibroblasts accelerate the accumulation of type I collagen. The collagen was accumulated in liver tissue not only cause liver fibrosis but also recruit much more platelets aggregate in liver and be activated at the same time. Then activated platelets secrete CXCL4 again. This mechanism speeds up the progress of liver fibrosis. However, when we knock out CXCL4 gene, activated platelets could not secrete CXCL4, so HSCs could not be activated. Which means that there are no more myofibroblasts increasing and no more accumulation of type I collagen in tissue. Therefore, the progress of liver fibrosis will be slow down.

That is pretty much it about my seminar subject. Honestly, it takes me about a week to finish this article. Maybe this article doesn't make any sense because of my unsuitable description in English. Let me know when it does happen.

My first interview.

I have never had an interview before. Today is the day when I have my first interview. It is an interview of applying a graduate school. And this is a really long story.

Long time ago, I decided to apply for graduate schools so I went to cram school preparing the exams. However, I don't really want to go to graduate school so I stopped studying after chinese new year. Before I took the exams, I just finished less than one fifth of all books. I never expected to pass.


I was freaked out when I took the exams. Most of the questions are questions and answers, not multiple choice, so rationally, I did it very bad. All I answered were only one third of whole questions and I was not sure for half of my answers. I took them very easy.

The consequences showed that I failed in two school, and passed in one school. I was really surprised that I can pass for the exams. I can't believe it at all. Therefore, I got a chance to interview. If I make it, I will go graduate school. The interview was not easy to prepare. I need two recommendation letters, and a report card, and my autobiography. The report card are easy because I can just apply one, but the others are difficult. First, I don't know how to write a good autobiography. I don't know what are needed in an autobiography so I searched in the internet, asked some people, and even copy some templates. I wrote one finally, but it seemed not good enough. Anyway, it is much better than nothing. Second, I have to ask two professors who is willing to write me an recommendation letter. Wow, I didn't know who should I ask because there are some records that professor would turn students down in letter, or even refuse to write one for students. Whereas, I was lucky to have two letters in the end.

Last but not least, I don't know what should I wear to be proper enough. Some people said I should wear very formally, some people said I don't need to wear too formally. besides, it cost me a lots of money to prepare what I wore. That is really a big deal!

When I was interviewing with professors, they asked many questions which is not related directly to the graduate school. They were like chatting. They didn't ask any professional questions. That made me really relive indeed but I just have a bad feeling of this interview. And the worst things is that I finished this interview much earlier than the other candidates. Dose it mean that I don't have any hope to go to that graduate school?

Working with Bacteria

I have been in microorganism lab for 2 weeks, working with bacteria. That really makes me exhausted. As the lab's name, all we do are about microorganism such as bacteria, fungus, and virus. However, the works I did these days are only about bacteria, and it is dangerous. Actually, not all bacteria can cause disease, and only few of them can, but this lab is full of disease-causing bacteria.

In hospital, common clinical samples are blood, urine, sputum, and body fluid. I think they are really disgusting because some of them were not well packed that makes samples leak out of containers. I asked to MT, " Why the samples are not well packed? Why don't we just reject them?" The answer really disappoint me. "We had rejected samples before, but the nurses were angry about that and complained to our chief who is a doctor, not MT. Sometimes they just yell back angrily", said a predecessor. Since then, MT will run tests if the orders and the samples are correct, regardless the quality and quantitative about samples. Doctors only care about the result.

The first thing we do when we get samples is the check sample, patient, and order if they are correct. Then, we classify samples by different kinds of tests such as aerobic and anaerobic tests and we inoculate samples on medium plates. Then, we can wait for the growth of bacteria. After bacteria growth on the plates, we select the colony which we want to know, and put it in a identified machine and wait for results. That is the main steps of procedure, but sometimes machines could be wrong so we would run other chemical tests or just confirm under microscopes. That is really difficult, and this is why MTs is professional. To most people, every bacteria looks the same no matter what kind of microscope do they use, and I am one of them. I spent times learning to tell the difference between bacteria, and now I know a little.

In this lab, MTs let us, interns, practice every procedures by our own, and learn thing during practicing. They seems trusted us very much, and sometimes they even didn't check whether we did correctly or not. Basically, we did everything except identify bacteria and report results. Therefore, we had to proceed samples quickly because there were many samples, maybe hundred of them a day. If we didn't proceed quickly, we would be off late. After my first day, I was exhausted, and late to be off work. Since then, I made myself become faster and faster in order to be off on time.

These days, I learned many things and experience the works of a MT. I have to say it is great but I am not sure if I will be a MT after graduating. Because there is no available for MT, and the payment become lower and lower. That is the worst story that I have ever heard.

Every Times I Meet a Patient

Although, MTs worked in the hospital, they seldom have chances to meet their patient. In fact, they won't see any patient unless there are some law issues. So, I think it is very boring to do the same things with the same people all day, and I think that the only thing can cheer MTs up is finding some new exam methods to make tests more accurate. However, there are still some good things about work in the lab, that is we don't need to deal with patients.

I was at the EKG room few weeks ago. There, I can contact to patients which makes me feel interested. I told patients what EKG is, and told them how to do this test. In the conversation, I feel that most of patients feel scared when they do any medical tests which they have never done before. Being a medical staff, our first job is to make patients feel at ease. It will be easy if I talk to "normal" person. Because most of people know what I said and do what I told them do do. However, few of patients are too old or too sick to understand what I said. It is a big problem to me. I always don't know what to do. Sometimes, I tried my best to communicate with them, but sometimes, I just did what I have to do.

I found that communicating with patients is very difficult. As a MT, I cannot tell patients the result of the test even I know. It can avoid argument with doctor when we have different diagnosis. So, if a patient ask about the result, we can only tell them we don't know. That really depress me.

First Day Be an Intern

Like every body's first time, people would feel nervous, anxious because they don't know everything well. They are afraid to do something wrong. Taiwanese people would be quiet at this moment because they believe silence is gold. However, there are still some people who may ask questions more positively, or express their feeling, but in most of time, this kind of people are not be liked by everyone. Actually, it is a good thing to be talkative because that is the way to learn things.

I am not a talkative guy. When I was in the first day to be an intern of medical laboratory scientist , we called MT for short because of the old name medical technologist, I could nearly speak. I was wondering whether my speech is appropriate or not. That made me quiet, and stood there like a wood. Unfortunately, all my partners are the same with me. When MTs were working, they seemed to be too busy to be interrupted. Of course, it was what I assumed because when I was young, my parents always told me that if the adults are busy, don't interrupt them, and if I have any question, I should ask later. Honestly, it is a very bad idea. That is why, there is always a problem that if I don't ask my question immediately, I would forget my question when people are free, or it would be very odd to ask a question about maybe 20 minutes ago after I found people are free. Therefore, I always have a lot of questions in my mind.

My first stop was at Genetic Diagnosis. All the examine methods are new. All the MTs are very busy, so they didn't have time to teach me. Then, I started to read some SOP(standard operate procedure) in the lab. It would be normal for me if I have questions about the SOP, but I kept my questions in my mind because I saw everybody was busy. Basically, what I did in my first day is just standing all day. I felt very tired after I offed the lab, and the most important thing is that I felt very very boring.