Myopathies series - Part 1

Hello :)

Before starting with the series, I will post on the basics you need to know for myopathies.

Q. What do you mean by muscular dystrophy and myopathy?

A. I found that following definition from Harrison is simple.

Skeletal muscle disease myopathies, are disorder with structural changes or functional impairment of muscle.

Muscular dystrophy refers to a group of hereditary progressive diseases with unique phenotypic and genetic features.

Do you know glycogen storage diseases?

Yes! But why do you need to mention it here? Because, skeletal muscles are the store house of glycogen. It gets converted into glucose-6-phosphate (Note:- Never in glucose unlike liver. Why? Otherwise glucose will move out from the myocyte to blood. And myocytes will fail to utilize their own stored glycogen. That is why muscle lack an enzyme called glucose-6-phosphatase.)

There are some glycogen storage disease which will lead to myopathies.

For now remember that myopathies have different way of presentation. 

Muscle weakness is one of the clinical feature.

The muscle weakness can either be 1. Intermittent or 2. Persistent.

If there is energy deficiency in muscle, it will become weak.

Today, we are focusing mainly on skeletal muscle energy metabolism.

Glycogen storage disease are described in the Roman numerals. Not all glycogen storage disease lead to myopathies. Some glycogen storage disease lead to myopathies is mentioned in the diagram.

 More is coming up.:) 

-Upasana Y.  

Pathophysiology of laboratory findings in tumor lysis syndrome

Which of the following electrolysi abnormalities will you see in tumor lysis syndrome?
Answer either high, normal or low for each of these - calcium, phosphate, potassium, uric acid.

Answers:
Labs in tumor lysis syndrome -
Hypocalcemia 
Hyperuricemia
Hyperphosphatemia
Hyperkalemia

Why?

When cancer cells lyse, they release potassium, phosphorus, and nucleic acids, which are metabolized into hypoxanthine, then xanthine, and finally uric acid. 

This leads to:

Hyperkalemia can cause serious — and occasionally fatal — dysrhythmias.

Hyperphosphatemia can cause secondary hypocalcemia, leading to neuromuscular irritability (tetany), dysrhythmia, and seizure, and can also precipitate as calcium phosphate crystals in various organs (e.g., the kidneys, where these crystals can cause acute kidney injury).

Uric acid can induce acute kidney injury not only by intrarenal crystallization but also by crystal-independent mechanisms, such as renal vaso-constriction, impaired autoregulation, decreased renal blood flow, oxidation, and inflammation.

Crystal-induced tissue injury occurs in the tumor lysis syndrome when calcium phosphate, uric acid, and xanthine precipitate in renal tubules and cause inflammation and obstruction.

That's all!

-IkaN

Causes of microcytic erythrocytosis

A high RBC count combined with a low mean volume is seen in:

1. Thalassemia minor, either alpha or beta
2. Polycythemia vera with iron deficiency
3. Secondary polycythemia (hypoxia) with incidental iron deficiency.

Differentiating thalassemia minor from polycythemia vera:

The RBC size distribution curves reliably distinguish between thalassemia minor and polycythemia with iron deficiency.

RDW is elevated in iron deficiency. It is normal in thalassemia minor.

That's all!

-IkaN

Type 2 RTA pathophysiology, notes and mnemonic

Hello! This post is on type 2 renal tubular acidosis.

What causes Type 2 RTA?
Defect in proximal bicarbonate reabsorption - resulting in a hypokalemic hyperchloremic metabolic acidosis.

The defect in proximal reabsorption of filtered HCO3-  in effect leads to decreased proximal NaCl reabsorption and a tendency for salt wasting. This causes hyperaldosteronism -  leading to increased K secretion by the distal nephrons.

Staphylococcal Scalded Skin Syndrome vs Bullous Impetigo

How do you differentiate Staphylococcal Scalded Skin Syndrome (SSSS) from Bullous Impetigo (BI)?

The exfoliative toxins are restricted to the area of infection in BI. In SSSS, infection is diffuse.

In BI, bacteria can be cultured from the blister contents. Cultures from blisters are negative in SSSS.

Blood cultures are usually negative in SSSS (positive in BI).

In SSSS, Nikolsky sign is positive. It is negative in BI.

In BI, patients are usually not ill appearing.

That's all!
-IkaN

Pills of knowledge in Ophthalm- squint and frontal eye field

Mentally challenged people may have a squint as the frontal eye field in the brain cortex is involved in ocular movements as well. It also may explain why somebody's eyes go crazy when they're starting into nothingness.

That's all!

-Sushrut Dongargaonkar

Settings for mechanical ventilation

These are my quick and dirty notes to help ventilator settings related questions on the USMLE.

Treponemal and nontreponemal tests for syphilis (notes + mnemonic)

Nontreponemal tests include:

Rapid plasma reagin (RPR)
Venereal Disease Research Laboratory (VDRL)
Toluidine Red Unheated Serum Test (TRUST) 

Mnemonic:
Do not trust VDRL rapidly.

Features of non treponemal tests:

They are based upon the reactivity of serum from infected patients to a cardiolipin-cholesterol-lecithin antigen. 

Used for initial syphilis screening due to their relatively low cost, ease of performance, and ability to be quantified for the purpose of following response to therapy.

Specific treponemal tests include:

Fluorescent treponemal antibody absorption (FTA-ABS)
Microhemagglutination test for antibodies to T. pallidum (MHA-TP)
T. pallidum particle agglutination assay (TPPA)
T. pallidum enzyme immunoassay (TP-EIA)
Chemiluminescence immunoassay (CIA)

Features of treponemal tests:

Treponemal tests have been more complex and expensive to perform than nontreponemal tests. Thus, they have traditionally been used as confirmatory tests for syphilis when the nontreponemal tests are reactive.

Treponemal tests are qualitative only and are reported as "reactive" or "nonreactive" 

Once a patient has a positive treponemal test, this test usually remains positive for life. Thus, these tests are generally not useful for confirming a diagnosis of syphilis in a patient with prior treated disease.

That's all!
-IkaN

Postural variations in pulmonary edema and embolism

Hey Awesomites

Patients with pulmonary edema prefer to be in an upright position, while those with pulmonary embolism prefer flat position.


This is because in cases of edema, there is excess fluid accumulation in lungs, which limits respiratory movements. In upright position, the fluid will settle down and thus it lowers the pressure in pulmonary vessels which makes it easier to breathe.

On the other hand, in case of pulmonary embolism, the patient  is placed in left lateral decubitus (durant maneouver) and Trendelenburg position immediately. The air embolus moves through the right side of heart to enter into the lungs. But in Durant's maneouvre and Trendelenburg position, the embolus gets trapped in the apex of the heart and so does not get transported through pulm arteries to enter the lungs.
Check this link for more detail on venous emboli management


Thats all
- Jaskunwar Singh

New drug launched for Sickle Cell Disease

Heyy guys, I have taken this post from Medscape. Nonetheless, awareness about this new drug should be spread.

The US Food and Drug Administration (FDA) has approved L-glutamine oral powder (Endari, Emmaus Medical Inc) to reduce severe complications of sickle cell disease in patients aged 5 years and older with the disorder. This is the first approval for the rare disorder in almost 20 years.

"Endari is the first treatment approved for patients with sickle cell disease in almost 20 years," Richard Pazdur, MD, acting director of the Office of Hematology and Oncology Products in the FDA's Center for Drug Evaluation and Research and director of the FDA's Oncology Center of Excellence, said in an FDA news release. "Until now, only one other drug was approved for patients living with this serious, debilitating condition."

The decision follows consideration of data from a randomized trial of patients aged 5 to 58 years who had suffered two or more sickle cell pain crises within the 12 months before enrollment in the trial. The researchers randomly assigned patients to receive L-glutamine or placebo. Treatment was evaluated during a 48-week period.

Those who received L-glutamine experienced fewer hospital visits for pain crises that resulted in treatment with parenteral narcotics or ketorolac, on average, compared with those who received placebo (median three vs median four), fewer sickle cell pain hospitalizations (median two vs median three), and fewer hospitalized days (median 6.5 days vs median 11 days).

Those who were given L-glutamine also experienced fewer episodes of acute chest syndrome — a life-threatening sickle cell disease complication — compared with those who were given placebo (8.6% vs 23.1%).

Frequent adverse events include constipation, nausea, headache, abdominal pain, cough, extremity pain, back pain, and chest pain.

L-glutamine received orphan drug designation for sickle cell disease. The FDA's Office of Orphan Products Development (OOPD) is intended to incentivize the development of drugs for rare diseases. Development of this drug was supported in part by the OOPD Grants Program, which provides grants to conduct clinical studies on safety and effectiveness of treatments for rare diseases or conditions.

Approximately 100,000 people in the United States have sickle cell disease, according to the National Institutes of Health. The disease primarily affects African Americans, Latinos, and other minority groups. The average life expectancy for those with sickle cell disease in the United States is 40 to 60 years.

-VM

Parkinson's disease associated with melanoma: Research update

Hey Awesomites

Patients with movement disorder such as the Parkinson's are at four-fold higher risk for malignant melanoma, and vice versa. This is likely due to mutual genetic, environmental and pathogenic ( immune system ) abnormalities and factors that they both share, as suggested by a research study at Mayo clinic.
( Source )

- Jaskunwar Singh

Causes of dilated cardiomyopathy mnemonic

Hi awesomites!

Here's a short note on causes Dilated cardiomyopathy.

It's mostly idiopathic.

Other causes are:

1. G enetic Mutation
2. Myocarditis

3.  Alcohol  abuse
4.  Drugs
5.  Pregnancy
6.  Hemochromatosis

Mnemonic.  GMM ADPH

That's all :)
 
H@Mid

Why do newborns have a higher heart rate?

Hey guys!

Have y'll ever wondered why do babies have heart rates as high as 160s?

Answer:
Babies have a high proportion of Body Surface Area to heart than that in adults. Therefore, in order to maintain adequate blood flow, baby's "li'l heart" has to pump more often to cover the "large Body Surface Area"!

I hope y'll find this interesting!

Till then, stay awesome!

-Rippie