User:Z3418981: Difference between revisions

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<pubmed>25128525</pubmed>
<pubmed>25128525</pubmed>
<pubmed>24397701</pubmed>
<pubmed>24397701</pubmed>
--[[User:Z8600021|Mark Hill]] These are all relevant references, and a sentence description for selection would also help. (4/5)


===LAB 4 ASSESSMENT===
===LAB 4 ASSESSMENT===

Revision as of 21:18, 6 October 2014

Lab Attendance

Lab 1 --Z3418981 (talk) 12:45, 6 August 2014 (EST) http://www.ncbi.nlm.nih.gov/pubmed PubMed PMID25084016 <pubmed>25084016</pubmed> Lab 2 --Z3418981 (talk) 12:17, 13 August 2014 (EST) Lab 3--Z3418981 (talk) 12:58, 20 August 2014 (EST) Lab 4--Z3418981 (talk) 11:48, 27 August 2014 (EST) Lab 5--Z3418981 (talk) 11:42, 3 September 2014 (EST) Lab 6--Z3418981 (talk) 11:51, 10 September 2014 (EST) Lab 7--Z3418981 (talk) 11:17, 17 September 2014 (EST) Lab 8--Z3418981 (talk) 12:30, 24 September 2014 (EST)

Individual Assessments

LAB 1 ASSESSMENT

Reference: PMID24726222

<pubmed>24726222</pubmed>

Summary of the Method

In this study, genomic DNA was extracted from the umbilical cord blood of a total of 185 newborn females. Patients included 60 infants conceived by intracytoplasmic sperm injection (ICSI) and 73 infants conceived by in vitro fertilization (IVF) all recruited from a number of IVF centers across Canada. In addition, 52 naturally conceived patients were recruited from hospitals across the Lower Mainland in British Columbia, Canada. A karyotype or comparative genomic hybridization (CGH) analysis of the chromosomes was performed for all newborn cases. Cases were not included if congenital and/or chromosome abnormalities were present.

The X-chromosome inactivation (XCI) assay was performed to determine the XCI skewing of different tissues in different parts of the placenta by assaying allelic ratio of methylated alleles at the androgen receptor(AR), fragile X mental retardation 1 (FMR1), and DXS6673E loci. Fisher's exact test was a statistical method used to compare the frequency of mildly skewed (≥75%) and extremely skewed (≥90%) XCI in the patients. The parental nature of the skewed allele was determined by automated fluorescence analysis which was used to measure the AR alleles of the maternal decidua of the placenta.

Summary of the Results

There was no statistically significant difference between the ICSI, IVF and NC populations in the frequency of skewing ≥75% (7.0% vs. 5.7% vs. 2.0%, respectively; P=.523) or ≥ 90% (0 vs. 1.4% vs. 2.0%, respectively; P=.747). The mean level of skewing between the ICSI, IVF, and ICSI groups also was not significantly different (63.7% vs. 61.8% vs. 60.7%, respectively). Only two samples were found to have extremely skewed cases (≥90% skewing): one IVF (89.6%) and one NC (90.6%). The parental origin of the preferentially inactivated X chromosome in these extremely skewed cases was maternal for IVF and paternal for NC case.


Reference: PMID24399508

<pubmed>24399508</pubmed>

Summary of the Method

All of the pregnancies conceived by in vitro fertilization in Denmark from 1995 to 2005 (n = 18 787) was included in this study using the data reported to the National In Vitro Fertilisation register (IVF register). Information about the pregnancy outcomes as well as cycle-specific information on the type and date of treatment, and the occurrence of pregnancy, abortions and deliveries was also obtained from IVF.

A study published by Virkus et al. on venous thromboembolism in pregnant and puerperal women in Denmark was used as a reference (Virkus et al., 2011). This study was used as a reference since the population used in this study (727 VTE patients among the 805 464 pregnancies recorded in the Danish National Patient Registry from 1995 to 2005) is ideal and comparable to the present study. Consequently, venous thrombosis incidence rates in pregnancies conceived by in vitro fertilization were compared with venous thrombosis incidence rates in reference pregnancies, by calculating incidence rate ratios.

Summary of the Results

The venous thrombosis incidence was significantly increased in pregnancies after in vitro fertilization. The overall ratio of venous thrombosis incidence rate during in vitro fertilization pregnancies to reference pregnancies was 3.0 (95% CI 2.1–4.3). The overall venous thrombosis incidence rate was 28.6 per 10 000 pregnancy-years (95% confidence interval (CI) 20.6–39.6) for pregnancies after in vitro fertilization compared to 10.7 per 10 000 woman-years in reference pregnancies.

Reference used in the "Summary of the Method" section:

<pubmed>21713323</pubmed>

LAB 2 ASSESSMENT

An overview of the process of fertilisation in mutant C. elegans.jpeg

Image showing the process of fertilisation in mutant C. elegans[1]

--Mark Hill (talk) 16:19, 21 August 2014 (EST) This is all correct. The image is very large (1.15 MB), perhaps a smaller image version could have been uploaded. You can adjust the resolution and size in most image editing programs.

  1. <pubmed>15086962</pubmed>|BMC Developmental Biology

LAB 3 ASSESSMENT

Abnormalities associated with neural development

<pubmed>12454899</pubmed> <pubmed>25007063</pubmed> <pubmed>16530991</pubmed> <pubmed>7504639</pubmed> <pubmed>19651588</pubmed> <pubmed>25135350</pubmed> <pubmed>25128525</pubmed> <pubmed>24397701</pubmed>

--Mark Hill These are all relevant references, and a sentence description for selection would also help. (4/5)

LAB 4 ASSESSMENT

1. Identify a paper that uses cord stem cells therapeutically and write a brief (2-3 paragraph) description of the paper's findings.


<pubmed>24104453</pubmed>

The inhibitory effect of human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) on the growth of C6 glioma cells was investigated in this study. Initially C6 cells were cultured with different concentrations of hUC-MSCs in order to examine whether the hUC-MSCs inhibition of glioma cell growth was mediated by soluble factors. It was found that hUCMSCs-CM exhibited a concentration-dependent inhibitory effect on C6 cell growth which in turn suggested that soluble factors in the conditioned media from hUC-MSCs were responsible for the inhibition of C6 glioma cells. Subsequently, flow cytometric analysis was used to test the effect of the soluble factors derived from hUCMSCs-CM on the cell cycle of glioma cells. Using this method, cell cycle status of C6 cells treated with different concentrations of hUCMSCs-CM was identified. It was observed that C6 cells treated with hUCMSCs-CM showed increases in the G0/G1 phase and reductions in the S phase compared to the control group (0 % hUCMSCs). These results suggested that hUC-MSCs could potentially inhibit the growth of C6 glioma cells and stop the cell cycle at the G0/G1 phase by secreting some soluble factors.

Western blot analysis was then performed and it was observed that the expression levels of β-catenin and c-Myc in C6 cells were reduced in the conditioned media derived from hUC-MSCs. These results indicated that some soluble factors secreted from hUCMSCs-CM may play a role in the inhibition of Wnt signaling pathway in C6 cells. Further investigations demonstrated that the secretion levels of dickkopf-1 (DKK1) were positively correlated with the concentrations of hUCMSCs-CM. Subsequently, the hypothesis that stem cells secreted Wnt inhibitors, such as DKK1, which could inhibit the Wnt signaling in tumor cells, was made.

Neutralizing antibody against DKK1 was then added to the hUCMSCs-CM in order to further confirm that DKK1 is a key factor in the inhibitory effect of hUCMSCs on C6 cell proliferation. It was observed that the inhibitory effect of hUC-MSCs on C6 cells was decreased when DKK1 was neutralized by anti-DKK1 antibody. Moreover, it was found that conditioned media from hUC-MSCs transfection with siRNA targeting DKK1 mRNA altered the regulation of the Wnt signaling in C6 cells. Therefore, it was concluded that hUC-MSCs inhibited C6 glioma cell growth by secreting DKK1, an inhibitor of Wnt pathway.


2.There are a number of developmental vascular "shunts" present in the embryo, that are closed postnatally. Identify these shunts and their anatomical location.


There are three developmental vascular "shunts" present in the embryo that are closed postnatally:

Foramen ovale (Foramen Botalli)

Foramen ovale is an opening in the inter-atrial septum which allows blood from the right atrium to enter the left atrium during foetal development. Foramen ovale allows blood to bypass the non-functional foetal lungs while the foetus obtains its oxygen from the placenta. A layer of cells exist over the foramen ovale during fetal development which acts as a valve and is known as septum primum. After birth, increased pulmonary blood flow and pulmonary venous return to left heart causes the pressure in the left atrium to be higher than the pressure in the right atrium. The increased left atrial pressure results in the closure of foramen ovale after birth.

Ductus venosus

In the foetus, the ductus venosus shunts blood from the left umbilical vein directly to the inferior vena cava and therefore allows oxygenated blood from the placenta to bypass the liver. Ductus venosus plays an important role in shunting oxygenated blood to the fetal brain.The ligamentum venosum which is usually attached to the left branch of the portal vein is the fibrous remnant of the ductus venosus

Ductus arteriosus (Ductus Botalli)

Ductus arteriosus connects the pulmonary artery to the proximal descending aorta. Ductus arteriosus prevents the output of the right ventricle from entering the unexpanded, fluid-filled and non-functional foetal lung. Therefore only enough blood reaches the foetal lungs to maintain the developing lung tissue. Ductus arteriosus becomes the ligamentum arteriosum after closing at birth.

LAB 5 ASSESSMENT

Azygos Lobe

Azygos lobe (also known as Adam's lobe) is a congenital malformation of the lung due to an alteration in the embryonic development of the azygos vein. Azygos lobe is a common congenital anomaly with an incidence of 1 in 100-200 of anatomical samples and 0.4-0.5% of chest radiographs. In general, azygos lobe means accessory lobe or supernumerary lobe of lung. There are three main types of azygos lobes: upper azygos lobe, lower azygos lobe and the lobe of azygos vein. The upper and lower azygos lobes are of very little clinical significance compared to the lobe of azygos vein.

During normal fetal development, the right posterior cardinal vein (precursor of the thoracic segment of the azygos vein) migrates over the apex of the right upper lung to occupy a medial mediastinal position. In the case of azygos lobe, an abnormal migration of this vein occurs and it penetrates into the right upper lobe. The right posterior cardinal vein carries the parietal and visceral layers of pleura with it and forms an accessory fissure made up of a total of four pleural layers called mesoazygos. The lung parenchyma located medial to the accessory fissure is called the azygos lobe.

Subsequently in the case of azygos lobe, the abnormal azygos vein crosses the apex of lung instead of its border and forms a fissure which separates the apex of the lung into medial and lateral parts. The medial part of the ruptured apex forms the lobe of azygos vein. Therefore the azygos lobe is a variably separated portion of the right lung and not an independent segment. Moreover, some course variability of the phrenic nerve have also been observed in the presence of an azygos lobe which is of importance when performing surgery.



References

<pubmed>16333920</pubmed> <pubmed>23705047</pubmed>


LAB 7 ASSESSMENT

1. Identify and write a brief description of the findings of a recent research paper on development of one of the endocrine organs covered in today's practical.

<pubmed>14561778 </pubmed>

In this study, the functional characterization of Arx, a gene encoding homeodomain-containing proteins that are potentially involved in endocrine pancreas development is being investigated. To study the role of this gene in pancreas development, loss-of-function mutant mice were generated by targeting the genes in mice embryonic stem cells. Arx-deficient mice developed severe and early-onset hypoglycaemia, dehydration and weakness and died only two days after birth. Immunohistochemical analysis of Arx mutant pancreas then revealed an absence of mature endocrine α cells and an increased number of β and δ cells. However, islet morphology and the total number of endocrine cells remained intact. These results suggested a requirement of Arx transcription factor for α-cell fate acquirement and a repressive action on β-and δ-cell destiny, which is exactly the opposite of the phenotype observed in Pax4-deficient mice.

Therefore, the results of this study suggest that a mutual cross-regulatory inhibition of these factors exist so that Arx promotes α-cell cycle and prevents β- and δ-cell proliferation whereas Pax4 favours β- and δ-cell fate and inhibits α-cell proliferation. It was demonstrated using multiplex reverse transcriptase PCR (RT-PCR) that Pax4 and Arx transcripts accumulate in Arx and Pax4 mutant mice, respectively. These results further suggest that the antagonistic functions of Arx and Pax4 for proper islet cell specification are based on the pancreatic levels of the respective transcripts.

2. Identify the embryonic layers and tissues that contribute to the developing teeth.

a) Neural-crest-derived mesenchymal cells that differentiate under the influence of the enamel epithelium form odontoblasts. Odontoblasts secrete predentin which calcifies to form dentin.

b) Epithelial cells give rise to ameloblasts that produce the enamel of the tooth.

c) Periodontal ligament is a special connective tissue structure that holds the tooth in place and surrounds the tooth root coating of cementum.