Month: September 2022

TENABLE. "I think it is fair to say that our suggestion that the Phase III Phenomenon is aging at the cell level is still a tenable hypothesis even after thirty years of study. That is not to say that it has been proven unequivocally to be correct. This has not happened because there are no universally accepted criteria for defining biological aging." http://protein.bio.msu.ru/biokhimiya/contents/v62/full/62111380.html View in LinkedIn

TRANSFORMING CELLS. "Immortal cell populations still occasionally arise spontaneously from normal cell cultures by an unknown process. Today, however, they can be created purposely, albeit at low efficiency, by exposing normal, mortal cells to radiation, chemical carcinogens or certain oncogenic viruses." http://protein.bio.msu.ru/biokhimiya/contents/v62/full/62111380.html View in LinkedIn

CHANGING PARADIGM. "Nevertheless, what seemed in the 1950's to be incontrovertible evidence that the fate of all cultured cells was immortality, soon fell to new insights and a preponderance of opposing information." http://protein.bio.msu.ru/biokhimiya/contents/v62/full/62111380.html View in LinkedIn

THE HAYFLICK LIMIT. "We showed that the death of cultured normal human cells was not due to some trivial cause involving medium components or culture conditions but was an inherent property of the cells themselves. The observation has since been confirmed in hundreds of laboratories." (Haflick). http://protein.bio.msu.ru/biokhimiya/contents/v62/full/62111380.html View in LinkedIn

RESISTANCE TO CHANGE. "The paramount dogma in cell biology was that the failure of cells to proliferate indefinitely in vitro must be attributable to errors in the "art" required to keep cells dividing forever. That dogma was so well entrenched that our original manuscript was rejected in 1960 by The Journal of Experimental Medicine." Science hates change. http://protein.bio.msu.ru/biokhimiya/contents/v62/full/62111380.html View in LinkedIn

REJECTION. "Hayflick’s study was published in Experimental Cell Research in 1961, after first being rejected by another prominent journal—The Journal of Experimental Medicine. The rejection letter came from Francis Peyton Rous who received the Nobel Prize a few years later for his discovery of chicken tumor viruses." https://lnkd.in/dQMB4k7 View in LinkedIn

RIDICULE. "Hayflick’s work was criticized and he was ridiculed. It took about 10 years for a more general acceptance that normal cells have a limited life span in vitro, a phenomenon now known as the Hayflick limit. The Nobel Prize–winning discovery of telomere shortening and the expression of telomerase explained Hayflick’s observations." https://lnkd.in/dQMB4k7 View in LinkedIn

ISOLATE CULTURES. "In protozoa where an individual is isolated and continuously separated from daughter cells as they are produced (‘isolate’ cultures), mortal lineages always occur, thus settling a controversy of 50 years duration. Alleged ‘immortal’ cell lines, like HeLa, that have been cultivated continuously for decades, but never studied as isolate cultures, cannot be assumed to be immortal." https://lnkd.in/esfPTAR View in LinkedIn

DISRUPTIVE SCIENCE. "In the 1960’s, Leonard Hayflick and Paul Moorhead overturned what was then a reigning paradigm in cell biology--that under optimal growth conditions, cells possessed an unlimited capacity for replication. Their elegant series of experiments convincingly showed that, on the contrary, human cells displayed a strictly limited division potential." https://lnkd.in/dppQZ73 View in LinkedIn

MUDDY POND. "Normal cultured cell populations are mortal but cells that are immortal are abnormal and most have properties of cancer cells. Nevertheless, this distinction becomes blurred because the terms ‘mortality’ and ‘immortality’ are subject to enormous variations in understanding." (Leonard Hayflick). https://lnkd.in/dPSTAYE View in LinkedIn