Adenylate cyclase regulation

Adenylate cyclase is dually regulated by G proteins (Gs stimulating activity and Gi inhibiting it), and by forskolin, as well as other class-specific substrates:

cAMP-dependent pathway, ASA the adenylyl cyclase pathway Mechanism

Mechanism of cAMP-dependent signaling. In this figure, the neurotransmitter epinephrine (adrenaline) and its receptor (pink) is used as an example. The activated receptor releases the Gs alpha protein (tan) from the beta amd gamma subunits (blue and green) in the heterotrimeric G-protein complex. The activated Gs alpha protein in turn activates adenylyl cyclase (purple), which converts ATP into the second messenger cAMP

Oxygen toxicity Mechanism

Mechanism

While all the reaction mechanisms of these species within the body are not yet fully understood,[55] one of the most reactive products of oxidative stress is the hydroxyl radical (·OH), which can initiate a damaging chain reaction of lipid peroxidation in the unsaturated lipids within cell membranes.[56] High concentrations of oxygen also increase the formation of other free radicals, such as nitric oxide, peroxynitrite, and trioxidane, which harm DNA and other biomolecules.[19][57] Although the body has many antioxidant systems such as glutathione that guard against oxidative stress, these systems are eventually overwhelmed at very high concentrations of free oxygen, and the rate of cell damage exceeds the capacity of the systems that prevent or repair it.[58][59][60] Cell damage and cell death then result.[61]
http://en.wikipedia.org/wiki/Oxygen_toxicity#Mechanism

What causes hypocalcemia in acute pancreatitis?

Acute pancreatitis is sometimes associated with tetany and hypocalcemia. It is caused primarily by precipitation of calcium soaps in the abdominal cavity, but glucagon-stimulated calcitonin release and decreased PTH secretion may play a role. When the pancreas is damaged, free fatty acids are generated by the action of pancreatic lipase. Insoluble calcium salts are present in the pancreas, and the free fatty acids avidly chelate the salts, resulting in calcium deposition in the retroperitoneum. In addition, hypoalbuminemia may be a part of the clinical picture, resulting in a reduction in total serum calcium. In patients with concomitant alcohol abuse, a poor nutritional intake of calcium and vitamin D, as well as accompanying hypomagnesemia, may predispose those with pancreatitis to hypocalcemia.http://answers.yahoo.com/question/index?qid=20080216161550AAXb89R

A New Botulinum Toxin formulation

Xeomin (incobotulinumtoxinA) is a new formulation of botulinum toxin type A for the treatment of adults with cervical dystonia or blepharospasm. Under natural conditions, Clostridium botulinum produces its toxin in association with additional complexing proteins. Historically, manufacturers have utilized this naturally occurring protein complex to produce therapeutic botulinum toxin products. The manufacturer of Xeomin uses a proprietary process that isolates the therapeutic component of botulinum toxin and eliminates the ancillary complexing proteins. In that regard, Xeomin has been formulated to have high biologic activity with a low protein load. Lower protein loads have been suggested to decrease the likelihood of developing neutralizing antibodies over time.

http://www.lexi.com/individuals/pharmacists/newsletters.jsp?id=august_10&utm_source=bdnewsletter&utm_medium=email&utm_campaign=august&contactID=14694955&gwkey=KYQPILTL7B

Gradual-Onset Headache and Vomiting in a 42-Year-Old Woman

A 42-year-old woman is referred to the neurosurgery outpatient department with a gradual-onset headache that is constant and located in the right half of her head. She has also had frequent, repetitive, nonprojectile vomiting not related to meal intake for 3-4 months. In addition, the patient has had cognitive defects for the last 3-4 months, especially a reduction of what she describes as "thinking power." She underwent enucleation of her left eye in a different hospital 8 years ago, the details of which the patient could not recall. No other significant medical history is known. The first-degree family members also report no significant medical or surgical history.


http://cme.medscape.com/viewarticle/726851?src=emed_case_nl_0&uac=149212BX

Altered Mental Status in a Young Man Picked Up On the Street

A 33-year-old man is brought by ambulance to the emergency department (ED) with altered mental status and agitation. He had called 911 from a pay phone, stating that people were trying to shoot him. Upon arrival of the police to the scene, the patient was reported to be visibly paranoid, so Emergency Medical Services (EMS) was called.......

http://cme.medscape.com/viewarticle/726722?src=emed_case_nl_0&uac=149212BX