G. Jakli

Naturally occurring deuterium is essential for the normal growth rate of cells

The role of naturally occurring D in living organisms has been examined by using deuterium‐depleted water (30–40 ppm D) instead of water containing the natural abundance of D (150 ppm). The deuterium‐depleted water significantly decreased the growth rate of the L929 fibroblast cell line, and also inhibited the tumor growth in xenotransplanted mice. Eighty days after transplantation in 10 (59%) out of 17 tumorous mice the tumor, after having grown, regressed and then disappeared. We suggest that the naturally occurring D has a central role in signal transduction involved in cell cycle regulation.

The vapor pressures of dimethyl sulfoxide and hexadeuterodimethyl sulfoxide from about 313 to 453 K

Abstract The vapor pressure of (CH3)2SO has been determined from 323 to 443 K by mercury manometry thereby extending the older (293 to 323 K) results of Douglas. A least-squares fit was made to the available data and is suitable from approximately 291. 7 K (the melting temperature) to 463 K, and is ln ( p Torr ) = 17.4922 – 4517.79 ( T K − 47.2583) . The vapor pressure difference, [ p“( CD 3 ) 2 SO ’ − p“ (CH 3 ) 2 SO ’ ], was measured by differential capacitance manometry between 323 and 368 K, and by mercury manometry between 383 and 463 K. The vapor pressure isotope effects derived from the results may be expressed by the equation: ln ( p D p H ) = −43454.6( K T ) 2 + 219.449( K T ) − 0.25996 . The isotope effect on the melting temperature Tm was determined as T m “(CD 3 ) 2 SO’ − T m “(CH 3 ) 2 SO’ = (2.30 ± 0.02) K , substantiating the prediction (above) of a change in sign of the isotope effect around 313 to 318 K.