The Guermantes Way III p 404-431

From George Painter's 2-volume biography of Proust, p. 330-31, (v.1, 1978 pb edition):

"Dr. Proust's dining-room was also an ideally situated strategic point for observing the natural history of doctors, and in particular the originals of Cottard, Du Boulbon, Dieulafoy and Professor E—. 

"Dr.Eugène-Louis Doyen (1859-1916), a surgeon of sensationally original technique, with greying blond hair, astonished blue eyes and an athletic figure, was a model for many qualities of Cottard: his icy brutality, naivete, inspired tactlessness, fury when contradicted by a patient, and total, incurable ignorance in cultural and social matters. "With all her gifts," he flabbergasted Proust by announcing, "Mme Greffuhle hasn't managed to make her salon anything like as brilliant as Mme de Caillavet's!" Dr. Doyen regarded himself as Potain's* superior— "Potain's an old fool," he would say—an opinion shared by Mme Verdurin. The dates of his life fit those of Dr. Cottard, who is young in the 1880s and dies during the war.

"Professor Guyon, the urologist and teacher of Robert Proust, was a tall, thin man with white whiskers, from whose inexhaustible puns and cliches Proust collected a store of hints for Cottard; and Auguste Broca was another surgeon who, like Cottard, kept his students in fits of laughter with puns, chestnuts and oaths. As we have seen, Cottard, as a foundation-member of Mme Verdurin's “little nucleus” and an unfaithful husband, was Dr. Pozzi at Mme Aubernon's; his pince-nez and involuntary wink were those of Proust's professor, Albert Vandal; but his name was taken from Dr. Proust's fellow-student Cotard and Dr. [Jules] Cottet at Évian.

"The model for Dr. du Boulbon was the favourite physician of the Faubourg Saint-Germain, Dr. Le Reboulet; but a guest of Dr. Proust, the warty-faced Dr.Laboulbène, contributed to his name.

"Dr. Dieulafoy, with his 'charmingly supple figure and face too handsome in itself,’ who is sent for simply to certify the grandmother's last agony and, says the Narrator at the time of writing, ‘is now no longer with us’, was a real person, Professor Georges Dieulafoy (1839-1911). He was Princesse Mathilda's doctor and guest, and Proust's friend Gabriel Astruc took him, no doubt with some good reason, for an original of Cottard.
Dr. Brissaud
"Professor E—, who automatically quotes poetry before examining the Narrator's grandmother, is Dr. Edouard Brissaud, author of Hygiene for Asthmatics, 'our dear médecin malgré lui on whom one almost has to use physical force to get him to talk medicine,' wrote Proust after consulting him in 1905.**

"Another friend of the Proust family and guest of Mme Aubernon was Dr. Albert Robin, who told Proust: "I might be able to get rid of your asthma, but I wouldn't advise it; in your case it acts as an outlet, and saves you from having other diseases.”

* Pierre Potain (1825 - 1901) was a French cardiologist.

** Proust told Lucien Daudet in 1921 that there was 'something of Brissaud's type of doctor, more a sceptic and a clever talker than a clinician, in Du Boulbon'. But it was [Proust's] habit not only to create a single character from several originals, but to distribute elements of a single real person over several characters.

Modern-day neurologists are still discussing the model for Dr. Cottard here
Denis Abrams' take on this scene  and the following one
p 431 | Uraemia:  the illness accompanying kidney failure (renal failure).
p 440 | Ciborium: liturgical vessel