A tiger-top blood sample drawn by a nurse was sent to the lab for a chemistry panel testing. You notice that the glucose level was over 800 mg/dl. Creatinine level was very low (0.5 mg/dL), sodium level was very low (108 mEq/L) and potassium was very high (6.9 mEq/L). Levels of most of the other analytes were ether normal or lower than normal. A check on the patient's history indicated that the previous tests results from earlier that day were all normal, except for slightly elevated lipids. You call for a redraw of the blood specimen from a different site than the previous. When you repeated the tests using this new specimen, the results were all normal. Briefly describe what is going on.
The results obtained from the first specimen are typical of those from specimens contaminated by dextrose IV fluid. So, the first specimen was most likely drawn through a dextrose IV line. When access to a patient's visible veins is very difficult, a last resort is to draw blood specimens from an IV line when available. However, recommended procedure must be followed to ensure that the IV fluid does not contaminate the blood specimen. By itself, the 5% dextrose usually used to supply patients with nutrients is equivalent to 5000 mg/dL. So, contamination of the blood specimen with small to moderate amount of the fluid can elevate the blood sugar level to well over 800 mg/dL, and dilute the sodium level to below 130 mg/dL. The potassium level most often is also elevated. So it looks like the IV line was not properly treated to ensure that the patient's blood had equlibrated before drawing the specimen. Checking previous results and repeating the tests with a specimen drawn from a different site helps to identify this problem.
Many diseases such as cancer and sickle cell anemia, are due to mutations in the DNA sequences of specific genes leading to the production of defective and disfunctional proteins. Depending on what genes are mutated, affected cells can overgrow and lead to tumors and cancers, or they can form other diseases. Briefly describe two ways that these genetic diseases can be cured using principles from Biochemistry, Molecular and Cellular Biology, Immunology, etc.
(i). The principles of gene expression has been applied in various ways to treat genetic diseases. For example, a normal copy of the mutated gene can be inserted into a DNA vector which contains viral DNA integration elements. When these vectors are introduced into cells inside or outside the body, they find their way into the cell nucleus and integrate into chromosomal DNA. The modified cells then use their gene transcription and translation machinery to produce functional proteins from the integrated vector. This technique has been used to cure an immune disease called ADA deficiency. (ii). A more desirable approach is a bio-technology that can be injected into animals or cells to penetrate the nucleus and chromosome, and find and directly correct the mutated gene so that the gene can produce functional proteins again. A version of such a technology (called CRISPR) has been developed and is being refined in clinical trials. It is being used to modify specific genes in the cancer-fighting immune cells, T-lymphocytes, so that they carry surface proteins that can seek out and destroy specific cancer cells. When these modified T-lymphocytes are injected into actual patients with the targeted cancer, they are expected to seek out and kill the cancer cells and bring about cancer remission, as have been observed in animal studies.
Why are clothes moths able to eat up and create large holes in woolen clothes?
Wool and silk clothes are composed of the fibrous protein, keratin. Keratin molecules contain extensive disulfide cross-links that act as bridges to stabilize the structure of the protein. This results in keratin being hydrophobic and insoluble in water. To digest keratin, an animal needs very specific enzymes and co-factors to split open its disulfide links so that regular digestive enzymes can break down the protein into its amino acids components. Most animals do not have the specific enzyme and co-factors. The larvae of clothes moths produce two unique enzymes, (cystine reductase and cysteine desulphydrase) tthat can split these disulfide bonds and open up keratin molecules for digestion. The clothes moth larvae also contain hydrosulfides which apparently act as co-factors to help the enzymes in disrupting the disulfide bonds.