Despite protests about a new law designed to crack down on gifts to doctors, several Massachusetts life sciences companies say they remain hopeful the regulations can be implemented in a way that doesn't hurt their ability to work with physicians. The law requires pharmaceutical companies and medical device makers to publicly disclose gifts and payments of more than $50 to healthcare professionals and places a ban on certain gifts. It also directs the Department of Public Health to draft extensive regulations restricting companies' marketing practices, using the national pharmaceutical industry's own voluntary "code of conduct" as a starting point. But in a letter addressed to lawmakers, Gov. Deval Patrick said the new rules are not intended to force companies to disclose confidential information, impede medical research, or block the training of healthcare providers.