In Vitro vs In Vivo Research / Testing

[Fin24]

joe cites

However, the in vitro and the in vivo antibiotic susceptibilities of Bartonella do not correlate well for a number of antibiotics; for instance, penicillin has no in vivo efficacy, despite the very low MICs observed in vitro.

the problem may be the use of the many ways to determine efficacy--MIC is only but one and it may not be that good.
The MIC is the lowest concentration of antimicrobial agent which inhibits the growth of the microorganism
in a culture tube or plate the lowest concentration of a drug that will INHIBIT the growth of an organism will not necessarily say anything about the drug effect in the body; or even if it has the same MIC in the body at all. OR if it did have the same MIC what mechanisms are being affected--and that assumption of relativity isnt assumed anyway.( meaning I havent seen any study say unequivocably that a low MIC in lab guarantees antibacterial action in body---or that it works the same way

maybe in the body, its slowing a protein synthesis but in culture its simply blocking nutrient uptake.

Unfortunately as poor as the comparisons may be between in vivo and in vitro--its all we have as a start point to look at the actions of a drug against an organism.and when comparing drug choices to what we already have.

there are also verbage usage issues as well

many labs use this definition

A current definition of the Minimum Inhibitory Concentration, MIC, is "the lowest concentration which resulted in maintenance or reduction of inoculum viability".

http://www.bionewsonline.com/2/what_is_mic.htm

and frankly maintianing viability is NOT what we want inside ourselves--so WHICH definition is any study using at any time???

BUT when you use that parameter of MIC to compare drugs to each other OR to compare drugs vs organsism in matched pairs of efficacy--then maybe it again becomes more useful.
( for example if you can show macrolides have better MIC than cephalosporins against gram negatives then you wouldnt want to choose Suprax to combat a gram neg infection over Zithromax)

you are trying to take as absolutes many things not meant to be used as such, and then cant obviously be assigned to expectations ( or failed expectations) according to your falsely assigned absolutes. in other words when all we have are generalizations and you try to make them into specifics then bemoan their failure, whose fault is that?

aside to Hammy

I worry about you because you wouldn't have made that mistake (oversight) in the past; you started that thread only about a year ago.

apparently you still think it necessary to get personal and passive-aggressively hint at anothers' deficits when again I say to you--methinks the POT is calling the old Kettle BLACK

I worry about YOU and your apparent need to slyly attack others

and btw when you ask:

Would it be impudent of me

usually the answer is YES, so why bother asking??? I can only hope you knew the answer and was attempting a cutesy post, unless we have to worry even more about YOUR state of health?? I hope not

before Cave even clarified her meaning of "remission" youre leaping at assumptions and presumptions--and I know exactly what she meant and Im guessing you did as well-- a stop of the progression of an illness along with an improvement of symptoms ( or even just a leveling off so symptoms dont worsen).

which has NOTHING to do with pain sensors being in the brain or not--so I find your thought process as worrisome as you find Cave's

ultimately I beleive her conclusion was that she didnt care IF any drug had in vitro vs in vivo differences as long as it did the job for her when she did take it. and ya know that DOES happen Hammy--having a drug that seems a poor candidate in the lab nonetheless effect major disease improvement once delivered into the body.

[cave76]

Hammy said:

*

****first reference quotes of the abstract only are to a 1990 paper that was funded by Glaxo, the manufacturer of cefuroxime (Ceftin)*****

I'm too busy to look for all the abstracts that Yvonne posted (or others) that might have 'suspicious' funding, but I'm sure they're here.

Or that the implications that you quoted from the abstract are not supported in the fine print of the full text?:
"the poorest results were obtained with penicillin G, in that no protection was obtained at doses as high as 74.5 mg/kg."

??????? I don't know of many Lymies who've ever used Pen G. So I'm confused why that's important here.

Cave quoting Wormser wrote:Extrapolation from studies with laboratory animals to humans should be done with caution.


I don't see how that is pertinent to a thread about in vitro vs in vivo research. Maybe in a separate discussion about human vs animal testing which might be very enlightening by exploring different metabolic mechanisms of pro-drugs, different immune responses, etc.

I'm sorry for putting that bit under this topic. I know that admin (and you) like topics to stay on topic and do keep an eye for any transgressions.

I'll post that in another topic. Thanks for pointing that out. You evidently did quite a bit of reading to find that Wormser was the author. Good catch.

I think that it's a good idea though, even if Wormser said it.

[Joe Ham]

I'm too busy to look for all the abstracts that Yvonne posted (or others) that might have 'suspicious' funding, but I'm sure they're here.

Yes, but we expect better of the Grand High Pooh-Bah.

??????? I don't know of many Lymies who've ever used Pen G. So I'm confused why that's important here.

Bicillin is Pen G plus procaine.
http://www.drugs.com/ppa/penicillin-g-b ... caine.html

[cave76]

Ah, yes---- I'd forgotten about the bicillin injections being pen g and procaine. My bad. I'd used the powder from Farmamondo and didn't read the French instructions---- just took my llmd's say so that it was the same as the bicillin given in the U.S.

Speaking of bicillin-------regardless of it's poor record according to ONE study:

http://www.pubmedcentral.nih.gov/articl ... tid=172012

"the poorest results were obtained with penicillin G, in that no protection was obtained at doses as high as 74.5 mg/kg."

------ I'd still have to say that, for me and maybe not everyone, my year long and plus weekly injections of bicillin occurred at the same time as my 'remission'. Coincidence? I don't know. But I've read plenty of others who also had good results from bicillin.

If my 'remission' had been coincidental with my Rocephin IV tx, then I'd say the same. A 'remission' is a "remission' and send some to my other generals.

So, yet another 'study' that was a snapshot in time. Proving nothing but what the authors and the funders wanted to prove.

In vivo vs in vitro.

1. Until there can be in vivo testing done in humans (and there are probably a zillion reasons why they can't)

and until

2. they can make a computer 'model' that actually works for each individual person

----- then each individual study has to be suspect. Too many variables, including the motives of the writers.

BUT perhaps as molecular medicine is perfected, that may be in the future. Let us pray.

[Fin24]

out of all the orals and IV abx and the altie stuff to the ONLY thing that ever helped Evan at ALL was the combination of IVIG and IM penicillin!!!

and according to his LLMD at the time he was getting the best results with IMpen when other protocols were failing even among pts w/o IVIG infusions

go figure

[Joe Ham]

Infect Immun. 1988 August; 56(8): 1831-1836

Changes in infectivity and plasmid profile of the Lyme disease spirochete, Borrelia burgdorferi, as a result of in vitro cultivation.
http://iai.asm.org/cgi/content/abstract/56/8/1831
http://iai.asm.org/cgi/reprint/56/8/1831.pdf

T G Schwan, W Burgdorfer and C F Garon
Laboratory of Pathobiology, Rocky Mountain Laboratories, National Institue of Allergy and Infectious Diseases, Hamilton, Montana 59840.

ABSTRACT

In vitro cultivation of Borrelia burgdorferi, the etiologic agent of Lyme spirochetosis, allows for the isolation and growth of this bacterium from infected tissues. However, continuous cultivation in modified Kelly medium causes a reduction in the number of detectable plasmids and the loss of infectivity in the white-footed mouse, Peromyscus leucopus.

In an unpassaged culture of B. burgdorferi, nine plasmids were present, including seven linear plasmids ranging in size from 49 to 16 kilobases (kb) and two circular plasmids of 27 and 7.6 kb.

The 7.6-kb circular and 22-kb linear plasmids were no longer detectable in spirochetes noninfective in white-footed mice, suggesting that a gene(s) encoding for factors responsible for infection may be present on one or more of these extrachromosomal elements.

Furthermore, changes in spirochetal proteins and lipopolysaccharide-like material were observed also during early cultivation and may be related to loss of infectivity.

[Fin24]

In case some ask " so what?" why are plasmids important?

Bacteria, including spirochetes, carry DNA within their chromosomes as well as OUTSIDE their chromosomes in "plasmids"

Plasmids are rings or pieces of DNA that can replicate independently of the cell's direction and can transmit genetic instructions as well as direct the cell's functions. The DNA of plasmids arent usually essential to the growth or survivial of that cell. It is used as a means of tranferring information between cells and can even integrate into the host cell's genome and become part of it. This is done both naturally and in the lab. Theyre quite useful in the lab when DNA has to be inserted into a host cell. By linking the target DNA inside a plasmid and injecting the plasmid into the cell, the DNA often can be induced to be incorporated and function.

http://www.biochemsoctrans.org/bst/028/02820000212.pdf

my summary:
the complete genome of extrachromosomal DNA of LYME's Borrelia burgdorferi ( strain B31, cultureM1) has been sequenced. there are 12 linear and 9 circular plasmids.there are more than 100 paralogous families of sequences among the plasmids.the ultimate consequence is many UNfunctional fragments of genes

the plasmids were found to have surprisingly small open frames meaning their functionality is very suspect to begin with.
A lot of damages were found on almost all of the linear plasmids ( this assumes a lot of previous recombinations and changes rendering them almost functionless)

ONLY 8% of the intact genes of all the plasmids even have the possibility of function due to similarities to already known genes.

it seems to me that while important to know they exist, these plasmids may not hold that much importance after all and the fact that they change while being cultured may also be meaningless within the context of In Vivo vs In Vitro. It may simply be an " artifact of occurrence" aka "coincidence"

[Fin24]

here is an alternate view from DR Rosa , NIH, NIAID who feels that Borrelia plasmids are indeed very important when trying to understand virulence and transmission between vector and host--and she claims there are many more plasmids and explains about them here:

http://www.lymeneteurope.org/forum/view ... f=5&t=2542