guides = Guide.objects.filter(author=user).order_by('-publish')[:10]
articles = Article.objects.filter(author=user).order_by('-publish')[:10]
memes = Meme.objects.filter(author=user).order_by('-publish')[:10]
comments = XtdComment.objects.filter(user=user).order_by('-submit_date')[:10]
result_list = sorted(chain(guides, articles, memes, comments), key=lambda instance: instance.publish) # <------- ??