"I'm still on P.A.S. and I may yet lose a rib or two"
X-ray showing TB in the patient's left lung
GNU Free Documentation LicenseX-ray showing TB in the patient's left lung - Credit: original uploader: EricH, Wikimedia Commons
P.A.S. is an abbreviation for many things, including 'primary alerting system' and 'performance assessment system'.

It is also the abbreviation for 'Periodic Acid-Schiff', a test carried out on human tissues in order to detect polysaccharides and other substances.

Does anybody know whether this has any bearing on TB?

One of the treatments available for tuberculosis between the early 1900's and the 1950's was Thoracoplasty, the surgical removal of one or more ribs in order to collapse a lung. With the advent of antibiotic drugs, such as streptomycin, this form of treatment for tuberculosis became increasingly rare from the late 1940's onwards, although it was still being practised in some parts of the world as recently as the late 1990's.