i have had this argument with the researchers at the University f= or 30 years, somewhere back in the day they were told that commercially mad= e formalin had methanol in it (it does but just a little and does not hurt = anything in my experience) and that methanol would damage their tissue for = IHC, so they think they must use paraformaldehyde and make it fresh themsel= ves. Since new people make it all the time it often does not get= made up correctly and their stress over this issue is miss placed as they = should be using something commercial for consistancy and paying more attent= ion to adequate time for fixation in reg formalin.
Another anoying myth that is difficult to combat with them is that "we= should limit the fixation time in aldehyde fixatives because it will cross= link the proteins masking them for IHC", there fore i am always getting ti= ssue that has not been fixed long enough (at least 24 hrs. to protect it fr= om paraffin processing, because if the proteins are not cross linked they c= an be alcohol fixed and/or washed away forever), the people in research kno= w about the cross linking fo aldehydes but do not know that cross linking o= f proteins is a good thing and they also do not know that we have advanced methods HIER or EIER for unmasking the proteins, but we have no way of gett= ing a protein back that has been lost in processing because the sample was = not adequately fixed. there i will get off my Friday soap box.................. Happy Holidays to all! Patsy -------- Original Message -------- Subject: RE: [Histonet] Silly= Question? From: Merced Leiker <lei...@buffalo.edu> Date: Fri, = December 12, 2008 8:12 am To: "Edwards, R.E." <r...@leicester.ac.uk&g= t;, 'Pat Flannery' <pjfne...@duke.edu> Cc: "'histo...@lists.uts= outhwestern.edu'" <histonet@lists.utsouthwestern.edu> In re= search lab situations particularly, one does not have the time or techn= ique for nailing down the ways of making each of the buffers, reagents,= and procedures work the "right" way or the most optimum way...a lot of= times it's students or postdocs just focused on getting their project = done and not caring how their fixative is made as long as it "works" to= some degree and, alas, it's up to us already over-booked technicians t= o figure out the best way to make the PFA....and we usually don't have = a whole day (week, or year) to spend researching the back-and-forth arg= uments, either! ;-) Merced --On Friday, December 12, 2008 2:0= 4 PM +0000 "Edwards, R.E." <r...@leicester.ac.uk> wrote: &= gt; You hit the nail on the head "That's what we always use", fear of &g= t; change is a common human condition. > > -----Original Messag= e----- > From: histonet-boun...@lists.utsouthwestern.edu > [[1]mailto:histonet-boun...@lists.utsouthwestern.edu]= On Behalf Of Pat > Flannery Sent: 11 December 2008 16:59 > To:= histonet@lists.utsouthwestern.edu > Subject: [Histonet] Silly Questi= on? > > Please humor me on this if it's obvious (to everyone bu= t me): why do > we use paraformaldehyde (which is so inconvenient to = make up) rather > than buffered formalin or just diluted formaldehyde= itself? > > It seems that around here, some folks prefer paraf= ormaldehyde (either > 2% or 4%) and others use formalin, while some o= thers stick to diluted > formaldehyde (I see all 4 on labels for spec= imens submitted for > histology). Is it mostly a matter of personal p= reference or where you > were trained (i.e. force of habit) or is the= re a valid reason to use > each solution (basically the same chemical= once in solution, merely > buffered or not)? The only answer I've go= tten when I've asked is, > "That's what we always use." > &g= t; Thanks. > > -Pat Flannery (not a "real" histologist - I just= play one in the lab) > > > _____________________________= __________________ > Histonet mailing list > histo...@lists.uts= outhwestern.edu > [2]http://lists.utsouthwestern.edu/mailman/list= info/histonet > > _________________________________________= ______ > Histonet mailing list > histo...@lists.utsouthwestern.= edu > [3]http://lists.utsouthwestern.edu/mailman/listinfo/histone= t > Merced M Leiker Research Technician II 3= 54 BRB (pkgs) / 140 Farber Hall (letters) School of Medicine and Biomedi= cal Sciences State University of New York at Buffalo 3435 Main St, Bu= ffalo, NY 14214 Ph: (716) 829-6033 Fx: (716) 829-2725 "Without= my flaws I'm really very boring." - random internet blog commentator _______________________________________________ Histonet mailin= g list Histonet@lists.utsouthwestern.edu [4]http://lists.utsouthw= estern.edu/mailman/listinfo/histonet References 1. 3D"http://email.secureserver.=/ 2. 3D"http://lists.utsouthwestern.edu/mailman/ 3. 3D"http://lists.utsouthwestern.edu/mailman/listinfo/his 4. 3D"http://lists.utso=/ _______________________________________________ Histonet mailing list Histonet@lists.utsouthwestern.edu http://lists.utsouthwestern.edu/mailman/listinfo/histonet
