Satellite DNA– A major component of centromeres is so-called satellite DNA, consisting of large arrays—up to megabases in length—of repeating sequences (from 5 bp up to 5 kb). Although classically associated with spindle apparatus attachment, satellite DNA is also important in maintaining the dense, tightly packed organization of heterochromatin.
Gene Editing and CRISPR- An exciting new development that allows high-fidelity genome editing may usher in the next era of the molecular revolution. This advance comes from a wholly unexpected source: the discovery of clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated genes (Cas), such as the Cas9 nuclease.
CHAPTER 2- ADAPTATIONS AND INJURY
Ferroptosis- Only discovered in 2012, ferroptosis is a distinct form of cell death that is triggered when excessive intracellular levels of iron or reactive oxygen species overwhelm the glutathione-dependent antioxidant defenses.
CHAPTER 3-INFLAMMATION AND REPAIR
Neutrophil extracellular traps (NETs)– NETs were mentioned in the previous edition it is further elaborated in the latest edition. Neutrophil extracellular traps (NETs) are extracellular fibrillar networks that concentrate antimicrobial substances at sites of infection and trap microbes, helping to prevent their spread.
CHAPTER 6- IMMUNITY
Rejection of tissue transplants:Elaborated compared to the previous edition.
CHAPTER 7- NEOPLASIA
A few newly added proto-oncogenes:
FMS-like tyrosine kinase 3 (FLT3) Point mutation or small duplications in Leukemia.
GTP-binding (G) proteins- GNAQ Point mutation in Uveal melanoma.
GTP-binding (G) proteins- GNAS Point mutation in Pituitary adenoma.
A few newly added tumor suppessor genes:
SDHB, SDHD (Succinate dehydrogenase complex subunits B and D TCA cycle, oxidative phosphorylation) seen in Familial paraganglioma, familial pheochromocytoma.
Elaboration of oncogenic activities of E6 an E7 proteins of human papilloma virus (HPV)
In the older edition it was mentioned that the E6 protein of HPV inactivates p53. In the 10th edition it is mentioned that in addition to inactivation of p53, E6 protein also increases telomerase expression (TERT).
COVID -19 second wave and journalism in India have introduced us to Black, white and yellow fungus. What are these originally? Let’s decode some terminilogy.
Before delving in let’s look at ways to differentiate two major opportunistic infections in COVID-19 patients based on morphology- MUCOR and ASPERGILLUS.
1. BLACK FUNGUS
What is being referred to as black fungus?
Mucor is being referred to as the black fungus.
Is the fungus itself black in colour?
No, in a setting of immunosuppression, mucor grows rapidly causing angioinvasion and tissue necrosis. This results in a blackish appearance of the affected area, giving rise to the name.
What is the real black fungus?
Some fungii have excess melanin, also called melanized or dermaticious fungi. They are the real black fungi. Moreover, presence of melanin is not uncommon in Histoplasma spp, Aspergillus spp (especially Aspergillus niger) and even candida spp.
2. WHITE FUNGUS
What is being referred to as white fungus?
Candida albicans. This fungus has the tendency to produce patchy white coloured lesions, hence the name.
3. YELLOW FUNGUS
What is being referred to as yellow fungus?
Mucor septicus. This fungus has not been associated with any human infections till now. It’s identification is still a mystery.
What is the real yellow fungus?
Aspergillus– When cultured, aspergillus has a blackish center due to the melanin, and whitish or yellowish body.
Actinomycetes has a unique feature, pus in this infection has a yellow color due to the presence of sulfur granules.
Gastrointestinal pathogens are very common in routine practice. It takes experience and keen observation to differentiate gastrointestinal pathogens from one another. In case of confusion, go with your ‘GUT’ feeling.
Lets look at a few differentiating features of Giardia lamblia, Cryptosporidium parvum and Isospora belli.
Pear shaped trophozoites with 2 ovoid nuclei, present in the luminal surface. They are 10-15 microns in length and 5-9 microns in width.
GIARDIA IS SEEN IN THE LUMINAL SURFACE
CRYPTOSPORIDIUM IS SEEN ATTACHED TO ENTEROCYTES LIKE SMALL BEADS.
2. CRYPTOSOPORIDIUM PARVUM
In tissue biopsies, 2 – 5 μm basophilic round bodies are seen protruding from the apex of enterocytes (“blue beads”) within the cell membrane. Parasites bulge out of apex of epithelial cells
ISOSPORA IS LARGEST AMONG THE THREE. IN CONTRAST TO GIARDIA AND CRYPTOSPORIDIUM – ISOSPORA DOES NOT HAVE AN APICAL LOCATION, INSTEAD LOCATED IN THE TIP OF VILLI.
3. ISOSPORA BELLI
Oocysts are generally ovoid to ellipsoid in shape, range from 10-40µm in length by 10-30µm in width. Cysts are present in PARASITO- PHOROUS VACUOLE. Does not have an apical location.