<?xml version="1.0" encoding="utf-8"?><!DOCTYPE Zthes SYSTEM "http://zthes.z3950.org/xml/zthes-05.dtd">  <Zthes><term><termId>19624</termId><termName>melatonin</termName><termType>PT</termType><termCreatedDate>0000-00-00 00:00:00</termCreatedDate><relation><relationType>BT</relationType><termId>18622</termId><termName>hormones</termName><termType>PT</termType></relation><relation><relationType>RT</relationType><termId>18915</termId><termName>sleep</termName><termType>PT</termType></relation><relation><relationType>RT</relationType><termId>19236</termId><termName>reproduction</termName><termType>PT</termType></relation><relation><relationType>RT</relationType><termId>18577</termId><termName>antioxidants</termName><termType>PT</termType></relation></term>  </Zthes>