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Lab 7
 
Lab 7
 
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Lab 8
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==Individual Assessment==
 
==Individual Assessment==

Revision as of 11:31, 19 September 2012

Lab Attendance

Lab 1 --Z3330986 11:49, 25 July 2012 (EST)

Lab 2 --Z3330986 10:25, 1 August 2012 (EST)

Lab 3 --Z3330986 10:33, 8 August 2012 (EST)

Lab 4 --Z3330986 10:21, 15 August 2012 (EST)

Lab 5 --Z3330986 10:27, 22 August 2012 (EST)

Lab 6 --Z3330986 11:55, 29 August 2012 (EST)

Lab 7 --Z3330986 10:54, 12 September 2012 (EST)

Lab 8 --Z3330986 10:31, 19 September 2012 (EST)

Individual Assessment

Lab 1

1) As with many medical terms, in vitro is derived from Latin, translating to "in glass." It is so named, as early experiments involving tissue cultures outside of the specimen (as opposed to in vivo, inside the body) were undertaken in glass containers. In Vitro Fertilization was developed by Robert G. Edwards. He was awarded the Nobel prize in 2010 in the field of medicine and physiology for his work. A link to the Nobel prize web page can be found here:[[1]]

2) Sperm counts and sperm sex ratio in male infertility patients[[2]]

In this study, the sex chromosomes and sperm count of infertile men were analysed in order to determine whether infertility plays a role in the determination offspring gender. Infertility is a fairly arbitrary categorization though for the purposes for this experiment, it was taken to mean couples who had greater than or equal to two recurrent pregnancy losses or two failed IVF treatments. The subsequent results found that in men with a low sperm concentration, semen volume and total motile sperm count, there was a significantly lower proprortion of the Y-bearing sperm. Thus there is a direct link between spermatogenesis and sex ratio.

The precise mechanisms for a diminished Y-bearing proportion of sperm is unclear. It is suggested that perhaps societal stresses or individual wants and needs may play a role in the genetic makeup of sperm. Biologically, it is reasoned that an infertile man will produce less male heirs so as to minimise the chance that his offspring may encounter the same problems.

Lab 2

Mouse oocytes in vitro

In order for successful implantation to occur, estrogen controlled proliferation of the uterine epithelium must be attenuated by the hormone progesterone. Previously the mechanisms of attenuation were not well understood however recent study has shown the helix-loop-helix protein, Hand2, plays an integral role in suppressing estrogen-driven growth of uterine epithelium. It does this by stopping the induction of Fibroblast growth factors (FGF) which are responsible for maintaining estrogen mediated growth of the epithelium. [1]

From a clinical perspective it may also direct research to improve treatments which target over-proliferative disorders such as endometriosis and endometrial cancer. Particularly endometriosis, which currently resists progesterone targeted medications.

Reference

1. The Antiproliferative Action of Progesterone in Uterine Epithelium Is Mediated by Hand2 Quanxi Li, Athilakshmi Kannan, Francesco J. DeMayo, John P. Lydon, Paul S. Cooke, Hiroyuki Yamagishi, Deepak Srivastava, Milan K. Bagchi, and Indrani C. Bagchi Science 18 February 2011: 331 (6019), 912-916. [DOI:10.1126/science.1197454]

Lab 3

1) Gestational age refers to the age of the foetus/embryo beginning at the first day of the mother's last menstrual cycle. In contrast the post-fertilisation age, as its name infers, begins at the time of fertilisation of the oocyte.

2) Somites mainly generate: Skeletal muscle and dermis (from the dermomyotome) as well as intervertebral discs and vertebral bodies (from the sclerotome)

Histology

  • Skeletal muscle - Contains densely packed fibers called myofibrils. These are cylindrical, long and multinucleated fibres with nuclei residing peripherally. Each myofibril is composed of the proteins actin and myosin (referred to collectively as myofilaments). Skeletal muscle can be divided into either red fibres or white fibres:
  • Red fibers are named due to the presence of myoglobin, an oxygen transporting protein, analagous to haemoglobin in the blood. They contain many mitochondria and are responsible for slow twitch contractile movements.
  • White fibers are larger with less myoglobin and mitochondria. These represent fast twitch fibers
  • Dermis - Bilaminar structure composed of Papillary layer and Reticular layer.
  • Papillary layer - Superficial layer interdigitating with the dermis. Composed of loose connective tissue with thin type III collagen fibers. Also contains macrophages, fibroblasts and mast cells along with capillary loops which function in thermoregulation.
  • Reticular layer - Deepest layer containing intermingling thick elastic fibers and collagen fibers.
  • Intervertebral disc - made up of fibrocartilage. The matrix contains cartilage cells, enclosed within lacunae which align in pairs or short rows between bundles of type I collagen fibers.

Lab 4

There are two main types of invasive prenatal diagnostic techniques

  • Amniocentesis - Amniotic fluid is taken and analysed between 14th and 18th week of pregnancy. It is used primarily to test for chromosomal defects such as Down Syndrome or fetal infections. It may be used to test for maternal hypertension (preeclampsia) by looking for protein biomarkers.
  • Chorionic villi sampling - Cells from the chorionic villus are taken between 10th and 12th week gestational age. It is used to test for chromosomal abnormalities such as Down syndrome or cystic fibrosis.

2) Systemic administration of a novel human umbilical cord mesenchymal stem cells population accelerates the resolution of acute liver injury

Traditionally when liver hepatocytes are damaged during end-stage liver disease, the only option has been transplantation. New research conducted by Burra et al (2011) however has focused upon using human umbilical cord mesenchymal stem cells (UCMSCs) as a form of regenerative treatment. In this study, UCMSCs were induced to form hepatic cell types through the use of growth factors in vitro, whilst ECM components derived from surgical specimens were used as a basis of support for these cells. These cells were then transplanted into carbon tetrachloride infected mouse livers which had undergone more than 40% necrosis of its total parenchymal tissue.

When UCMSCs were recruited within liver tissue, it was found that inflammation had been reduced through the regulation of pro-inflammatory cytokines and reduction of infiltrate. Furthermore there was a higher proportion of Kupffer cells (liver macrophages) identified through histological analysis compared to untreated liver tissue. This finding lends weight to the idea that UCMSCs accelerate liver cell recovery by attenuating the inflammation process.

Another therapeutic advantage of UCMSCs was the increase of catalase activity. The amount of catalase enzyme present in UCMSC treated liver tissue was markedly increased around Day 5, resulting in enhanced elimination of reactive oxygen species (ROS) which would otherwise cause oxidative damage to hepatocytes.

Lab 7

1a) A satellite cell, also referred to as a muscle stem cell, is a quiescent cell which functions to repair and or form new muscle fibres.

b) Activation of satellite cells occurs primarily during muscle injury. When a muscle fibre is damaged through physical injury, the satellite cells become mytotically active and fuse with the existing muscle fibres to repair the damaged tissue. Similarly in chronic diseases such as Duchenne’s muscular dystrophy, satellite cells are activated and differentiate into new myotubes in order to replace dying muscle fibres.

2) Damage to the motor nerve, classified as a motor neuron lesion, manifests in flaccid paralysis in the affected individual. This is a result of the loss of electrical signalling from the motor nuclei of the spinal cord to the muscle spindle. Consequently the individual presents with reduced muscle tone (hypotonia) and muscle wasting (atrophy). On a cellular level, muscle fibre size decreases whilst there is a fibre type shift from type I to type II fibres. This represents a down regulation of the slow myosin heavy chain (MHC) isoform and up regulation of fast MHC isoforms. [1]


References

1. Scelsi, R (2001). Skeletal Muscle Pathology after Spinal Cord Injury: Our 20 YearExperience and Results on Skeletal Muscle Changes in Paraplegics,Related to Functional Rehabilitation. Basic Appl Myol 11 (2): 75-85,