Of the common causes for exudative pleural effusions, parapneumonic effusions have the highest diagnostic priority. Even in the face of antibiotic therapy, infected pleural effusions can rapidly coagulate and organize to form fibrous peels that might require surgical decortication.
Retrogradation is the landward change in position of the front of a river delta with time.etrogradation is the landward change in position of the front of a river delta with time.
Retrovirus. A retrovirus is an RNA virus that replicates in a host cell through the process of reverse transcription. First it uses its own reverse transcriptase enzyme to produce DNA from its RNA genome, reverse of the usual pattern, thus retro.