from typing import Optional
import re


def isolate_timestamp_in_release(release: str) -> Optional[str]:
    """
    Given a release field, determines whether is contains
    a timestamp. If it does, it returns the timestamp.
    If it is not found, None is returned.
    """
    match = re.search(r"(\d{4})(\d{2})(\d{2})(\d{2})(\d{2})", release)  # yyyyMMddHHmm
    if match:
        year = int(match.group(1))
        month = int(match.group(2))
        day = int(match.group(3))
        hour = int(match.group(4))
        minute = int(match.group(5))
        if year >= 2000 and month >= 1 and month <= 12 and day >= 1 and day <= 31 and hour <= 23 and minute <= 59:
            return match.group(0)
    return None