At first it tought it as short for 'natural science'
but later I have also found 'NS-Medizine' referred to the human genetics scientists in nazi Germany

Example:
["Auschwitz, NS-medicine and its victims" Comments by 3 human genetics
scientists on the book by Ernst Klee].

It could be a German abbreviation, try asking somebody with German and science knowledge in the German-English language pair.

Yes, NS medicine stands for National-Socialist Medicine, though what the Nazi's did in the concentration camps has nothing at all to do with what any normal human being refers to as "medicine".

There were several branches of "research". They "studied" how long people survived in tanks filled with water only slightly above freezing temperature. They intentionally infected people with all sorts of diseases and watched them die. They performed indescribable experiments on twins.

One of the leading "scientists" was Josef Mengele, the Angel of Death, the Devil Doctor of the Auschwitz camp.

Here's a sample from the website below: "He took daily blood samples from his children, and sent these to Professor von Verschuer in Berlin. He injected blood samples from one twin into another twin of a different blood type and recorded the reaction. This was invariably a searingly painful headache and high fever that lasted for several days. In order to determine if eye color could be genetically altered, Mengele had dye injected into the eyes of several twin subjects. This always resulted in painful infections, and sometimes even blindness. If such twins died, Mengele would harvest their eyes and pin them to the wall of his office, much like a biologist pins insect samples to styrofoam. Young children were placed in isolation cages, and subjected to a variety of stimuli to see how they would react. Several twins were castrated or sterilized. Many twins had limbs and organs removed in macabre surgical procedures that Mengele performed without using an anesthetic. Other twins were injected with infectious agents to see how long it would take for them to succumb to various diseases."

Enough now. I'm sick again.