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Tutor profile: Luis L.

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Luis L.
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Questions

Subject: Portuguese

TutorMe
Question:

Fill in the blank with the proper verb tense: Minha mãe ______ (to want) que eu fosse à escola hoje, mesmo com o tanto de neve que havia ali fora. Por isso fiquei em casa, e pedi para que ela ______ (to do) um chocolate bem quentinho para a gente beber.

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Luis L.
Answer:

Minha mãe queria que eu fosse à escola hoje, mesmo com o tanto de neve que havia ali fora. Por isso fiquei em casa, e pedi para que ela fizesse um chocolate bem quentinho para a gente beber.

Subject: Biomedical Science

TutorMe
Question:

Cytokines are vital for our body's ability to fight pathogens. One important pathway that induces the production and secretion of cytokines is the MyD88-dependent TLR signaling pathway. Briefly describe this pathway. What are some signals that can activate it? What are the physiological outcomes from this pathway?

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Luis L.
Answer:

Cytokines are small peptide messengers that are vital for cell-cell signaling. In the case of the immune system, cell-cell signaling is crucial to "communicate" the presence of a pathogen. TLRs are transmembrane receptors that sense Pathogen Associated Molecular Pattern (PAMP) such as double-stranded RNA present in viruses. Upon activation, the TLR pathway leads to the recruitment of the MyD88 protein, which recruits other proteins that eventually activate the IKK protein. The IKK phosphorylates IkB (inhibitor of kappa B), thus leading to its degradation, thus activating the NF-kB transcription factor. This transcription factor leads to the transcription of cytokines such as TNF-alpha, IL-1beta and IL-6. These three cytokines lead to several physiological responses such as fever. TNF-alpha, IL-1B and IL-6 act as pyrogens and are received by the hypothalamus. The hypothalamus, then, acts on brown adipocyte tissues to generate heat, thus increasing the body temperature. This response helps fight the infection because pathogens such as bacteria cannot replicate well at higher temperatures.

Subject: Biology

TutorMe
Question:

You have designed a mouse with a loss of function mutation in the JG (Juxtaglomerular) cells (that is, all of the normal physiological functions in these cells are inhibited) . You want to investigate the importance of these cells in the mouse's ability to regulate blood pressure. Describe the role of the JG cells and how they are important for blood pressure regulation. What would happen to these mutant mice?

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Luis L.
Answer:

The juxtaglomerular cells are renal cells involved in the Renin Angiotensin Aldosterone System. These cells produce Renin -- a crucial protein for the RAAS pathway. JG cells release renin in response to low blood pressure and are also stimulated by the ion concentration in the blood. Once released, renin cleaves angiotensinogen (a protein produced by the liver) and produces angiotensin 1. Angiotensin 1 is converted to angiotensin 2 by the endothelial cells in the blood vessels. Consequently, angiotensin II is responsible for increasing blood pressure by constricting smooth muscles in vessels, inducing the release of ADH hormone and increase more water retention. Therefore, the mutant mice lacking functional JG cells are unable to increase blood pressure. Because of that, these mice are more likely to die due to hypoperfusion of the organs (inability to increase blood pressure when it's low would likely decrease the body's ability to deliver oxygen to vital organs such as the brain).

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