Leukocytes in urine are not a dangerous condition, but they are a sign that you are suffering from an infection or damage. Leukocytes are white blood cells (WBC) that work with the immune system to defend against infectious disease. Damage to the kidneys, ureters, urethra or bladder can cause leukocytes to appear.
Empty vessels is a metaphor for a very shallow person whose thoughts and actions have no significant meaning. Such people are constantly talking or otherwise making noise in an attempt to get attention from other people. The more the person is ignored because he has no real input to give, the louder he will become.
5. a spluttering noise made with the tongue and lips to express contempt (esp in the phrase blow a raspberry) [C17: from earlier raspis raspberry, of unknown origin + berry: C19 in sense 5, from rhyming slang raspberry tart fart]