Browsed by
Month: December 2023

Mushroom Misery

Mushroom Misery

Shiitake dermatitis is a big price to pay for the joy of shiitake mushrooms.  The dermatitis consists of intense itching that occurs shortly after ingesting raw or undercooked shiitake mushrooms.  Characteristic of the rash are raised, red streaks which is also called “flagellate erythema” because it literally looks like the sequela of being whipped.  Other than this characteristic appearance, the dietary history is the cue to diagnosis.    

It responds quickly to oral antihistamines and/or steroids.  It is prevented by adequate cooking of the mushrooms.  But some Eastern health supplements may also contain raw shiitake. 

The shiitake mushroom contains lentinan, a sugar molecule called 1,3 beta-glucan.  In mice experiments when its given intravenously it has anti-cancer and anti-viral benefits.  For cancer it disrupts harmful intra-cellular signaling that helps cancer spread.  For viruses it inhibits tissue cells from absorbing the harmful virus.  Given orally to mice it has no benefit.  It also increases the production of an immune molecule called interleukin-1 (IL-1).  It’s the IL-1 that causes vasodilation (dilation of skin capillaries) and rash. 

Supplements or Not 

Supplements or Not 

The Journal of the American Medical Association recently published a study done by scientists in Cambridge, Mass.  This group did refined chemical analysis on 60 different health supplements.  Their findings were very disconcerting.  Just 11 percent of the products contained an accurate amount of the key ingredients listed on the label.  Forty percent had none of the indicated ingredients.  Forty Five percent had inaccurate amounts varying from .02 percent of the amount listed to 334 percent of the amount listed. Finally, 8 percent of the products contained at least one compound prohibited by the US FDA. 

As opposed to prescription medicines, the FDA does not have authority to approve supplements before they are marketed.  The agency does require that OTC products contain what they indicate. 

Just because a product is on the market does not mean it’s safe, much less effective.  This is probably where an ounce of skepticism is worth a pound of cure.

Thymus

Thymus

Scientists at Mass General Hospital in Boston recently published findings on 1,150 adult patients in their hospital who underwent thymectomy (removal of the thymus gland). 

The thymus gland is a bit of a mysterious organ found in our chest that is most active in early childhood.  It is located in the chest between the lungs and just above the heart.  In infants the gland is large and completely covers the front of the heart. 

Until this recent study scientists have thought that the thymus played its key role in immune development in childhood and then withered away.  After puberty the gland shrinks to a very small size and is replaced by fat.  To surgeons it looks like a little blob of fat. 

In the Harvard study 2,300 adults had chest surgery and in 1,150 of them the thymus was removed during the surgery because “it was in the way” and was not felt to be needed.

For years, the thymus was felt to be only active during childhood.  It pumps out T lymphocytes, immune cells that have many functions.  The “new” T-cells can be formatted to do a variety of immunologic jobs.  Adults rely on memory T-cells, which are long lived cells that can be re-directed (teach an old dog new tricks) for special tasks.  Because of this “standard model of thymic function “the surgeons did not think removing it would be of consequence.  But it turns out that they were wrong. The thymus is not expendable after all. 

Within five years after surgery 8 percent of the thymectomy patients died compared to 3 percent of those whose thymus was not removed during the operation.  Cancer risk within 5 years was also double in the thymectomy group.  Finally, the thymectomy group had double the incidence of new auto-immune diseases. 

Needless to say, the Harvard scientists were shocked by these findings.  It is unclear what removal of the thymus changed.  Perhaps the “blob of fat” is still producing a few new T-cells.  Or perhaps the involuted thymus still subserves some type of immune-protective-surveillance not yet recognized.  At any rate these findings have led to both a change in surgical tactics and also new immunologic research to study thymic function in adults. 

Chronic PPI Use and Asthma

Chronic PPI Use and Asthma

New research shows that prolonged use of proton pump inhibitors (PPI’s) can increase the risk for developing asthma.  PPI’s are the “drugs of choice” for esophageal reflux, gastritis and gastric ulcers.  But their long-term use impacts the gut microbiome which in turn can cause immune dysregulation.  It is this “tilting” of immune function that increases the risk for asthma.  Prolonged use of PPI’s by women during pregnancy also increases the risk for their child to develop asthma. 

One strategy to lessen this risk is to use the PPI to gain control of the problem and then segue to an H2 antihistamine such as Pepcid (famotidine). 

Cross Reactive Epitopes & Food Allergy

Cross Reactive Epitopes & Food Allergy

A recent article in the Journal of Allergy and Clinical Immunology provided an update on our understanding of cross reactivity. 

First by way of definition an epitope is a discreet (usually small) portion of a molecule that is the binding target of an antibody.  In the case of allergic problems, the antibody is IgE.  By way of example think of distinguishing features that help you identify a car:  the Mercedes Star and the Dodge Ram. 

Allergy is directed at this epitope, not at the very large complete molecule.  As it turns out certain epitopes are found on both foods and airborne allergens.  The most common examples are crustaceans and dust mites, tree nuts and birch pollen, wheat and grass pollen.  The cross reactivity can be a two-way street where exposure to a food worsens an airborne allergy or vice versa.  Also, allergy shots for the airborne allergen can actually reduce the food allergy by desensitization reactivity to the shared epitope.  What will be very interesting to find out is whether desensitization to foods will help airborne allergy.  Food desensitization is still in its infancy with peanut desensitization being the main inroad in this regard.  But many academic centers have ongoing research to develop therapies for other common food allergens; milk, egg, wheat, soy and corn.  Stay tuned. 

Dear Dr. K;

Dear Dr. K;

I’ve seen you and multiple other doctors for what has been called unexplained chronic cough.  Now I’ve read about the new drug Gefapixant.  Do you think I’m a candidate?

My answer is a qualified yes. But before I continue my answer let me first give a summary of your own situation that might be of help to other kindred spirits.  Your cough is called “unexplained” because despite our best efforts the medical specialists you’ve seen have failed to find a cause.  Your primary doctor listened to your lungs (normal) and ordered a chest x-ray (normal) and a CT scan (normal).  Your ENT did nasal endoscopy and a sinus CT, both of which were normal.  Your allergist (me) did allergy tests that were negative.  Your pulmonary doctor did a series of breathing tests and even a methacholine challenge test, all of which were normal.  He did have you try some inhalers which did not stop your chronic cough.  Your gastroenterologist did an upper GI x-ray and then an endoscopy both of which were normal.  Your speech pathologist examined your larynx and vocal cords and found no abnormality.  And yet, you continue to cough. 

Gefapixant is an antagonist (blocker) of the P2RX3 receptor.  This receptor functions as a ligand-gated ion channel for nociceptor activation.  I’m sorry for all the big words, but basically a nociceptor is a sensor that tells a nerve that it is being stimulated.  This sensor is activated through an entrance doorway called an ion channel. 

As it turns out this particular receptor plays a role in sensing pain, sensing the need to empty our bladder and sensing the need to cough.  And you might correctly guess the medication is being studied for these applications as well. 

Compared to placebo Gefapixant 45mg twice a day reduced cough frequency and cough severity and improved cough-specific quality of life.  Its main side effect was causing taste perversion.