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Aminoglycosides - why -mycin and -micin

The aminoglycoside group includes gentamicin, amikacin, netilmicin, kanamycin, tobramycin, streptomycin, paromomycin and neomycin. These drugs have a good action against aerobic gram-negative bacteria. They are rapidly bactericidal. Bacterial killing is concentration dependent: The higher the concentration, the greater is the rate at which bacteria are killed. As noted above, some of the names end by -micin while others by -mycin. The reason behind this lies in the origin of the antibiotics. All the antibiotics ending with -mycin are either natural products or semisynthetic derivatives of compounds produced by a variety of soil actinomycetes notably Streptomyces . Those ending with -micin are derived from other actinomycetes e.g Micromonospora.

Atrial septal defect device closure

This procedure is called as Atrial septal defect (ASD) device closure. Transesophageal echocardiography (TEE) is must before procedure for: 1) actual sizing of the defect 2) defining the rims - to hold device in place 3) ruling out anomalous pulmonary venous drainage 4) ruling out significant mitral regurgitation (MR). Intraprocedural TEE is not mandatory. N.B How to distinguish between an ASD device and a patent foramen ovale (PFO) device? Left atrial (LA) disk (green arrow) is larger than Right atrial (RA) disk (yellow arrow), thus it is an ASD device.For a PFO device, RA disk will be larger than LA disk. Further readings:

A case of Mycobacterium marinum infection in a fisherman

Historically recognized as “swimming pool” or “fish tank” granuloma. Clinical features: Most infections occur 2 to 3 weeks after contact with contaminated water from one of these sources. The lesions are most often small violet papules on the hands and arms that may progress to shallow, crusty ulcerations and scar formation. Lesions are usually singular. However, multiple ascending lesions resembling sporotrichosis can occasionally occur. Most patients are clinically healthy with a previous local hand injury that becomes infected while cleaning a fish tank or patients may sustain scratches or puncture wounds from saltwater fish, shrimp, fins and other marine life contaminated with M. marinum. Swimming pools seem to be a risk only when non-chlorinated. Diagnosis: Diagnosis is made from culture and histologic examination of biopsy material, along with a compatible history of exposure. Treatment: No treatment of choice is recognized for M. marinum. However, successful treatmen

COPD exacerbation - definition, assessment, management

COPD exacerbation: Definition: Exacerbation of COPD is defined as an acute episode, characterized by the worsening of the patient’s respiratory symptoms that is beyond normal daily variations and that will eventually lead to a change in his medications. Those having 2 or more exacerbations per year are known as “frequent exacerbators”. Precipitating factors: 1) Respiratory tract infections – viral or bacterial. Most common cause. There may be an increased bacterial burden in the lower airways or new strains of bacteria are acquired during an exacerbation. Commonly implicated viruses include rhinovirus, respiratory syncytial virus, coronavirus and influenza virus. 2) Air pollution. 3) Interruption of maintenance therapy. 4) Unknown causes – 30% cases. Diagnosis: Diagnosis should be made clinically whereby the patient complains of an acute aggravation of his symptoms out of proportion to his day to day variations.  Assessment: Medical history: 1) Se

Hyperemesis gravidarum - definition, epidemiology, pathophysiology, complications, management

Definition: Mild to moderate nausea and vomiting are seen commonly until approximately 16 weeks in most pregnant ladies. Although nausea and vomiting tend to be worse in the morning, thus erroneously termed morning sickness, they frequently continue throughout the day. In some cases, however, it is severe and unresponsive to simple dietary modification and antiemetics. Hyperemesis gravidarum is defined as vomiting sufficiently severe to produce weight loss, dehydration, alkalosis from loss of hydrochloric acid and hypokalemia. Rarely, acidosis from partial starvation and transient hepatic dysfunction develop. Modified PUQE scoring index  (Pregnancy-Unique Quantification of Emesis and Nausea) can be used to quantify the severity of nausea and vomiting.  Epidemiology: There appears to be an ethnic or familial predilection. The hospitalization rate for hyperemesis is around 0.5 to 0.8%. Hospitalization is less common in obese women. In women hospitalized in a previous pregnan

Calcinosis cutis

Competitive, uncompetitive and non competitive enzyme inhibitors

(A) Enzyme–substrate complex;  (B) a competitive inhibitor binds at the active site and thus prevents the substrate from binding;  (C) an uncompetitive inhibitor binds only to the enzyme–substrate complex;  (D) a noncompetitive inhibitor does not prevent the substrate from binding.

Visceral and parietal layer of serous pericardium

Pericardium The pericardium is a fibroserous sac surrounding the heart and the roots of the great vessels. It consists of two components,  1) the fibrous pericardium and  2) the serous pericardium. The fibrous pericardium is a tough connective tissue outer layer that defines the boundaries of the middle mediastinum.  The serous pericardium is thin and consists of two parts: 1) The parietal layer lines the inner surface of the fibrous. 2) The visceral layer adheres to the heart and forms its outer covering. The parietal and visceral layers of serous pericardium are continuous at the roots of the great vessels. The narrow space created between the two layers of serous pericardium, containing a small amount of fluid, is the pericardial cavity. This is pictured in the diagram above as a fist in a filled balloon. This potential space allows for the relatively uninhibited movement of the heart. Fibrous pericardium The fibrous pericardium is a cone-shape