From Ben Olam Haba Web site:
A male may not extend his hand to shake the hand of a female, even though this is commonly done in the non-Jewish world as a courteous way of greeting and not for purposes of love, pleasure or closeness.
A female that fell or otherwise needs assistance getting up or needs medical assistance may be helped to her feet or given other medical assistance by a male [as this is not being done for purposes of closeness, love or pleasure].
Obviously, even when assisting her, the physical contact should be kept to the bare minimum deemed necessary and he should be careful not have impure thoughts while touching her. (See Shach Yoreh Deah Siman 195:20)
Of course, even when being treated by a female medical provider, he must be careful to not gaze unnecessarily at her.