Article Review 5

Cerebral Perfusion Pressure In Women With Preeclampsia Is Elevated Even After Treatment Of Elevated Blood Pressure

Maternal deaths from preeclampsia occur mainly due to cerebral infarction and hemorrhage, possibly due to increased cerebral perfusion pressure (CPP). High CPP has been linked to preeclamptic symptoms and eclamptic seizures. Labetalol and MgSO4, drugs used to control hypertension in preeclamptic patients, cause a decrease in CPP, while another antihypertensive drug, nimodipine, causes CPP to increase. Nimodipine is associated with more eclamptic seizures, possibly due to the increase in CPP. The purpose of the study was to evaluate the CPP in preeclamptic women with blood pressure controlled by antihypertensives. The CPP was calculated using zero-flow pressure and mean arterial blood pressure measurements. The zero flow pressure, arterial blood pressure, CPP, and CFI were all higher in preeclamptic women than control women. Additionally, a correlation was found between mean arterial blood pressure and CPP in preeclamptic patients, but not in controls.

As cerebrovascular complications are the main cause of death to preeclamptic women, and preeclampsia affects 3-8% of all pregnancies, this study is relevant. The authors used two methods to calculate the CPP, and, in both cases, the CPP was higher for preeclamptic women. Additionally, the authors report that the CPP calculated for the control patients was similar to that reported in other studies, which shows consistency between studies. The authors did, however, use non-invasive methods to measure the CPP, which have not been validated in humans. Nevertheless, they got similar results with both calculations of CPP.

Future studies could include trials with additional or alternative antihypertensive medications to bring the CPP to normal levels along with the blood pressure. The effect of lower CPP on the risk of cerebrovascular complications can then be observed. Additionally, studies could be done to validate the techniques for non-invasive measurement of CPP in humans.

Sonneveld, Milan J., et al. “Cerebral Perfusion Pressure In Women With Preeclampsia Is       Elevated Even After Treatment Of Elevated Blood Pressure.” Acta Obstetricia Et Gynecologica Scandinavica 93.5 (2014): 508-511. Academic Search Complete. Web. 20 Oct. 2016.

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Article Review 4

CXCR4, CXCR7, and CXCL12 Are Associated with Trophoblastic Cells Apoptosis and Linked to Pathophysiology of Severe Preeclampsia

The purpose of this paper was to examine the expression of the chemokine CXCL12 and its receptors, CXCR4 and CXCR7, in placental tissues and primary trophoblasts from preeclamptic and normal pregnancies. CXCL12 and its receptors are involved not only in the immune system, but also in various other processes, including remodeling the spiral arteries to form the placenta. CXCL12 and CXCR4 have been shown to be involved in trophoblast proliferation and invasion and decidual stromal cell migration and motility; lack of either of these functions is associated with preeclampsia. The authors examined the association between these proteins and preeclampsia.

Placentas were obtained after a cesarean section (21 normal pregnant, 11 mild preeclamptic, and 18 severe preeclamptic). A scanning electron microscope was used to observe morphological changes of trophoblast cells in preeclamptic placentas that caused a significant tendency towards apoptosis. Immunohistochemistry showed that there were lower levels of CXCR4, CXCR7, and CXCR12 were lower in severe preeclamptic placentas than in normal placentas. RT-qPCR was used to show that the same pattern was true for mRNA expression of the proteins, and Western blot analysis confirmed for protein expression levels in trophoblasts. The authors concluded that apoptosis of the cytotrophoblast cells may be regulated by expression of CXCR4, CXCR7, and CXCL12.

All three proteins have been shown to be important for proper placenta formation, so I think the research to compare expression between normal and preeclamptic patients is necessary and relevant. I think the study was well designed, especially by using different techniques to confirm results. However, the number of samples was small, only 50 in total, probably because the placenta was required for testing.

It would be interesting to see if the results in this study were replicated in a future study with more samples. While the study observes a decrease in the three proteins studied, more studies are required to understand the how they relate to the pathophysiology of preeclampsia. Additional studies should be done to understand the mechanism of cytotrophoblast invasion and how CXCL12 and its receptors relate to this.

 

Lu, Jing, et al. “CXCR4, CXCR7, And CXCL12 Are Associated With Trophoblastic Cells Apoptosis And Linked To Pathophysiology Of Severe Preeclampsia.” Experimental And Molecular Pathology 100. (2016): 184-191. ScienceDirect. Web. 9 Oct. 2016.

Article Review 3

An RGS2 3’UTR Polymorphism is Associated With Preeclampsia in Overweight Women

Preeclampsia is a pregnancy-associated syndrome initiated by poor placental perfusion which, together with maternal genetic and metabolic risk factors, cause the maternal response. The regulation of G-protein signaling 2 (RGS2) gene has been implicated in blood pressure regulation by inhibiting vasoconstriction mediated by G protein-coupled receptors. Low RGS2 levels is associated with hypertension and obesity. One cause of low RGS2 levels is the 3’ UTR C1114G polymorphism in the RGS2 gene (mutation rs4606). This study used obstetric and perinatal data to classify pregnancies as preeclamptic or normal control and as normal, overweight, or obese based on the mother’s pre-pregnancy body mass index. The rs4606 mutation was in Hardy-Weinberg equilibrium, though no association between preeclampsia and the rs4606 mutation was found under a dominant, recessive, or additive model. However, the CG and GG genotypes were significantly associated with preeclampsia in overweight women. The researchers concluded that RGS2 function could contribute to the increased rate of preeclampsia in overweight women.

All of the study participants had extensive clinical background information available for admission into the study and for classification of the pregnancies. Since the study included women from all Finnish university hospitals, the participants were representative of the Finnish population. The critical value for the statistical tests was 0.05, which is generally accepted as statistically significant data. Additionally, over 1300 preeclamptic and 600 normal pregnancies were included in the study, which is a decent size.

The rs4606 mutation in the RGS2 gene is associated with metabolic syndrome in white European men, weight gain in young hypertensive men, personality traits and brain function linked to anxiety disorders, and lower benefit from sertraline treatment to social anxiety disorder. Therefore, women with the mutation could be at higher risk of postpartum depression in addition to the known cardiovascular and insulin resistance problems after pregnancy. More research should be done to determine the role of RGS2 and the effect of the rs4606 mutation on that role.  Similar studies should include data on participants’ personality traits and anxiety disorders to determine if this mutation could explain some of the link between preeclampisa and anxiety/depression.

Karppanen, Tina, et al. “An RGS2 3’UTR Polymorphism is Associated With Preeclampsia in Overweight Women.” BMC Genetics 17. (2016): 1-7. Academic Search Complete. Web. 9 Oct. 2016.

Week 8

In molecular biology on Monday, Dr. Peng discussed site specific recombination of DNA. We learned the mechanism of both tyrosine and serine recombinases, as well as examples of each. On Wednesday we reviewed the two classes of transposable elements and their mechanism of mobilization (cut-and-paste vs. long terminal repeat mobilization). Finally, we went over V(D)J recombination, which is essential in the development of a functional vertebrate immune system. B cell and T cells undergo V(D)J recombination to provide immunity to a wide range of potential toxins.

Last week in biochemistry, we discussed protein metabolism, starting with an overview of the genetic code, such as codon and amino acid pairing. Next, Dr. Popescu talked about the mechanism of protein synthesis.  On Thursday, we talked about antibiotics that target translation as well as protein targeting and degradation. In bacterial physiology, we took Test 2 on Tuesday, and began a new section on Thursday on metabolism. The first part was on regulation patterns such as feedback inhibition. We discussed the trp operon as an example of positive regulation and the lac operon in E. coli as an example of negative regulation.

In genetics lab we ran a restriction length polymorphism analysis on colonies selected last week.  The results will be compared across the class to see which groups started with the same organisms.

Week 7

In molecular biology on Monday and Wednesday, Dr. Peng discussed DNA damage and repair mechanisms including nucleotide excision repair, non-homologous end joining, and translesion synthesis. For the honors paper in this class, I decided to write about the molecular biology of preeclampsia, as I have previously researched the pathophysiology of the disease. In biochemistry, Dr. Popescu reviewed DNA technologies beginning with the mechanisms of cloning. On Thursday, she continued with reviews of polymerase chain reaction amplification of DNA, electrophoresis separation of DNA, and DNA genotyping.  The second part of the lecture was about eukaryotic gene expression in bacteria.

In bacterial physiology on Tuesday, Dr. Roberts handed back quizzes and midterm grades, answered any questions about any lecture material, and listed important topics for the test on Tuesday. On Thursday, four groups presented papers titled Antimicrobial effects of silver nanoparticles, Capsule switching and antimicrobial resistance acquired during repeated Streptococcus pneumoniae pneumonia episodes, Effects of fermented sumach on the formation of slime layer of Staphylococcus aureus, and Membrane lipoteichoic acid of Streptococcus pyogenes and its stabilized L-form and the effect of two antibiotics upon its cellular content. These papers in addition to all the others presented in class will be on the test on Tuesday, so I have read through the papers again during my studying for the test.

 

In bacterial genetics lab on Friday, we selected colonies that had the recombinant plasmid. The microbial DNA, if taken into the plasmid, would have disrupted the gene for X-gal utilization. When transformed into E. coli that were plated on an agar with X-gal, the E. coli with non-recombinant plasmids would grow into blue colonies, since they could utilize the X-gal. The E. coli with recombinant plasmids, since they could not utilize X-gal, grew into white colonies. My lab partner and I had fewer colonies than the rest of the class, so we selected all our colonies, while the rest selected white colonies.

Week 6

In molecular biology on Monday and Wednesday, Dr. Peng discussed DNA replication.  We reviewed the full process of replication as well as how it is regulated.  In bacterial physiology on Tuesday and Thursday, we covered membrane bioenergetics, starting with a section on transport mechanisms (diffusion, solute transport, and group translocations).  A section on protein transport followed, which covered the Tat and Sec secretion systems in E. coli. The final sections were bacterial respiration, proton potential, and the electron transport chain.

Biochemistry class on Tuesday was an introduction to enzymes.  One thing that I did not remember well was the catalytic mechanisms of enzymes, which include acid-base, covalent, metal ion, and electrostatic catalysis mechanisms.  Another topic I have previously struggled with is enzyme kinetics, so I will make sure to study that in detail before the next test.  On Thursday Dr. Popescu discussed nucleotides and nucleic acids.  None of the information in that lecture was particularly new or challenging since we have already discussed nucleic acids in molecular biology and bacterial physiology.

On Friday I was traveling to a wedding in Colorado, so I was unable to go to bacterial genetics lab or communications.  My lab partner conducted PCR product cloning on two of our PCR products from last week (the two that showed strongest bands on the gel electrophoresis).  She started with ligation of the PCR product, then transformed the plasmid into E. coli.

Week 5

This week began with a review in molecular biology in preparation for the first test on Wednesday.  The test included DNA and RNA structure, the genome structure and organization, and techniques used in molecular biology labs.  On Tuesday morning, I had another review in biochemistry I for the first test on Thursday.  Needless to say, I spent a lot of this week studying for both of these tests.

On Tuesday afternoon, two of my bacterial physiology classmates and I presented a PowerPoint summarizing a research paper.  We were the first group to present, and I am relieved that I don’t have to worry about doing that later in the semester when there is more going on in other classes.  Our paper was titled “Inhibition of Bacterial Cell Division Protein FtsZ by Cinnamaldehyde.”  On Thursday, Dr. Roberts started a lecture on membrane bioenergetics, though we only got part way through the lecture on transport through bacterial cell membranes.

I took the two tests on Wednesday and Thursday, and finished up the week in bacterial genetics lab and communications on Friday.  In the lab, we ran a gel electrophoresis to visualize the DNA we amplified last week.  We also prepared our samples to run in a nested PCR, which will amplify only parts of the genes that were amplified last week.  This is sometimes necessary because, while the 18S RNA genes are highly conserved between species, there can still be some differences that interfere with amplification of the gene.