What is the test for abandoning a claim in a pro se appeal?

Federal Rule of Appellate Procedure 28(a)(6) provides that an appellant's brief "must contain the contentions of the appellant on the issues presented, and the reasons therefor, with citations to the authorities, statutes, and parts of the record relied on." Because the Madans's brief does not comport with the requirements of Rule 28, their claims are deemed abandoned. See Acosta-Huerta v. Estelle, 7 F.3d 139, 144 (9th Cir.1993) (holding, in pro se appeal, that claims not supported by argument are deemed abandoned unless failure to consider the claims would result in manifest injustice.)