Onderzoek persister cells

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Sproetje
Berichten: 3171
Lid geworden op: Di 28 Okt 2014, 20:33

Onderzoek persister cells

Berichtdoor Sproetje » Zo 09 Nov 2014, 19:53

Northeastern University
Antimicrobial Discovery Center

Kim Lewis, "The Paradox of Chronic Infections"

http://www.northeastern.edu/adc/researc ... ter-cells/

All bacterial populations stochastically produce a small number of dormant persister cells tolerant to antibiotics. Persisters are not mutants but phenotypic variants of the wild type.

We are interested in discovering the mechanism of persister formation. Using cell sorting and transcriptome analysis, we find that chromosomally-encoded “toxin” genes act to shut down cellular functions, creating a dormant state. Examples include HipA, which encodes a protein kinase that phosphorylates elongation factor Ef-Tu, blocking protein synthesis, and TisB, a small peptide that inserts in the membrane, causing a drop in pmf and ATP levels. Interestingly, TisB synthesis is induced by DNA damaging agents, including fluoroquinolone antibiotics. This means that persisters can be formed not only stochastically, but through stress response mechanisms.

We find that in chronic infections such as cystic fibrosis, antibiotic treatment selects for high-persister mutants. Whole genome sequencing indicates the mechanism for increased production of persisters.

Current projects involve the study of the molecular mechanisms of persister formation governed by HipA and TisB in E. coli; the search for persister genes in P. aeruginosa, S. aureus and M. tuberculosis; and characterization of high-persister mutants from clinical isolates of these pathogens. A related project is discovery of compounds capable of eliminating persisters. The work of the persister group is supported by a Transformative Award from the NIH, and with grants from ARO and CF Foundation.
Laatst gewijzigd door Sproetje op Ma 30 Jan 2017, 19:30, 1 keer totaal gewijzigd.

tulpje
Berichten: 94
Lid geworden op: Zo 09 Nov 2014, 20:32

Re: Onderzoek persister cells

Berichtdoor tulpje » Di 11 Nov 2014, 13:22

Kim Lewis over persister cells:

https://www.youtube.com/watch?v=qXTPiJWhtDg

Sproetje
Berichten: 3171
Lid geworden op: Di 28 Okt 2014, 20:33

Re: Onderzoek persister cells

Berichtdoor Sproetje » Vr 12 Jun 2015, 19:00

Borrelia burgdorferi, the causative agent of Lyme disease, forms drug-tolerant persister cells.


Bijaya Sharma, Autumn V. Brown, Nicole E. Matluck, Linden T. Hu and Kim Lewis
2015


http://aac.asm.org/content/early/2015/0 ... C.00864-15


(.......)
In this study, we examined the ability of B. burgdorferi to form persisters. Killing of growing cultures of B. burgdorferi with antibiotics used to treat the disease was distinctly biphasic, with a small subpopulation of surviving cells. Upon regrowth, these cells formed a new subpopulation of antibiotic-tolerant cells, indicating that these are persisters rather than resistant mutants. The level of persisters increased sharply as the culture transitioned from exponential to stationary phase. Combinations of antibiotics did not improve killing. Daptomycin, a membrane-active bactericidal antibiotic, killed stationary phase cells, but not persisters. Mitomycin C, an anti-cancer agent that forms adducts with DNA, killed persisters and eradicated both growing and stationary cultures of B. burgdorferi. Finally, we examined the ability of pulse-dosing an antibiotic to eliminate persisters. After addition of ceftriaxone, the antibiotic was washed away, surviving persisters were allowed to resuscitate, and antibiotic was added again. Four pulse-doses of ceftriaxone killed persisters, eradicating all live bacteria in the culture.

Sproetje
Berichten: 3171
Lid geworden op: Di 28 Okt 2014, 20:33

Re: Onderzoek persister cells

Berichtdoor Sproetje » Vr 12 Jun 2015, 19:23

Ik geloof dat Dr. Horowitz ook behandeld met pulsen van antibiotica.

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Lola Lyme
Berichten: 377
Lid geworden op: Di 28 Okt 2014, 20:53

Re: Onderzoek persister cells

Berichtdoor Lola Lyme » Do 26 Nov 2015, 21:52

Breaking News! – What everyone was waiting for – Possible Lyme Disease Cure on Horizon

Gepubliceerd op 13 nov. 2014
All the lies are starting to come out folks, breaking news has just surfaced that Ying Zhang, MD, PhD developed a test that can identify persister cells in Chronic Lyme Disease. Borrelia burgdorferi persister cells neither die nor grow in the presence of an antibiotic. Rather, they exist in a dormant state that allows them to survive antibiotic treatment, only to awaken later and start a new wave of infection. This new test will be able to quantify how many Borrelia burgdorferi are alive and how many are dead after each drug was added to the bacteria. The method stains the living bacteria green and the dead or dying bacteria red in a way that filters out the noise that can corrupt existing tests. So now, it's only a matter of time till the CDC changes their protocol and week can seek immediate antibitiotic treatment.

Breaking News!!! - Possible Lyme Disease Cure on Horizon
♪♪♫♫ 'The soul always knows what to do to heal itself. The challenge is to silence the mind' ♫♫♪♪

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Lola Lyme
Berichten: 377
Lid geworden op: Di 28 Okt 2014, 20:53

Re: Onderzoek persister cells

Berichtdoor Lola Lyme » Zo 29 Nov 2015, 19:24

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Laatst gewijzigd door Lola Lyme op Wo 04 Jul 2018, 15:39, 2 keer totaal gewijzigd.
♪♪♫♫ 'The soul always knows what to do to heal itself. The challenge is to silence the mind' ♫♫♪♪

Sproetje
Berichten: 3171
Lid geworden op: Di 28 Okt 2014, 20:33

Re: Onderzoek persister cells

Berichtdoor Sproetje » Wo 02 Dec 2015, 14:20

Peer Reviewed Evidence of Persistence of Lyme Disease Spirochete Borrelia burgdorferi and Tick-Borne Diseases

The following is a list of over 700 peer reviewed articles that support the evidence of persistence of Lyme and other tick-borne diseases. It is organized into different categories—general, psychiatric, dementia, autism and congenital transmission.


http://www.drgregorybach.com/media/accf ... ffe905.pdf


230 peer-reviewed studies show evidence of persistent Lyme disease

http://norvect.no/230-peer-reviewed-stu ... e-disease/

PS

Heb het verouderde pdf veranderd, en een link toegevoegd.
Laatst gewijzigd door Sproetje op Ma 09 Jul 2018, 17:44, 2 keer totaal gewijzigd.

Sproetje
Berichten: 3171
Lid geworden op: Di 28 Okt 2014, 20:33

Re: Onderzoek persister cells

Berichtdoor Sproetje » Do 31 Mar 2016, 18:55

Researchers investigate four promising new treatments for Lyme disease

March 29, 2016 by Thea Singer

Uit: news@Northeastern

http://www.northeastern.edu/news/2016/0 ... e-disease/

........
A new regimen

Lewis and his col­leagues are pro­viding that focus. A sub­pop­u­la­tion of B. burgdor­feri cells, they dis­cov­ered ear­lier, are “per­sister” cells—they are alive but lie dor­mant, in a spore­like state. Because antibi­otics attack only actively func­tioning bac­te­rial cells, per­sis­ters escape the onslaught. How­ever, once the antibi­otic has been flushed from the system, the per­sis­ters “wake up,” says Lewis, dividing and mul­ti­plying until an army of progeny infect the host.

That’s where “pulse dosing” comes in. Lewis’ team, in col­lab­o­ra­tion with researchers studying B. burgdor­feri in mice at Tufts University’s School of Med­i­cine, has been ana­lyzing the effect of giving the mice an antibi­otic that kills all the actively func­tioning bac­te­rial cells and then—using the timing that erad­i­cated the pathogen in the test tube—giving addi­tional doses to quash the per­sister cells as they begin to wake up but before they reproduce.

Plans are in the works for the first pulse-​​dosing human trials with med­ical schools.

Drugs com­bined and discovered

Doxy­cy­cline may be stan­dard first-​​line treat­ment for Lyme, but, says Lewis, it doesn’t even kill B. burgdor­feri, it just sup­presses its growth, leaving the rest of the work to the immune system. “We simply asked the ques­tion: ‘Is it pos­sible to com­bine existing antibi­otics to treat not only chronic Lyme but any stage of Lyme if the diag­nosis is unambiguous?”

The researchers have already found com­bi­na­tions that are effec­tive against the B. burgdor­feri in the test tube and will move on to animal studies next.

They are tack­ling new-​​drug dis­covery on two fronts: Plumbing the 200,000-plus com­pounds in their col­lec­tion at North­eastern to find the ones that act solely against B. burgdor­feri to avoid unwanted side effects and, in col­lab­o­ra­tion with Novo­bi­otic Phar­ma­ceu­ti­cals, extracting drugs from bac­teria that live in soil using the iChip, a device devel­oped by Slava Epstein, Dis­tin­guished Pro­fessor at North­eastern, in col­lab­o­ra­tion with Lewis. The iChip pro­vides access to the 99 per­cent of microbes in the envi­ron­ment that hereto­fore could not be grown in the lab.

“So far we have iden­ti­fied two lead com­pounds that kill B. burgdor­feri and have no activity against other bac­teria,” says Lewis.

The researchers are also exploring whether the micro­biome has “shifted” in those with PTLDS, to see whether intro­ducing cer­tain microor­gan­isms might shift it back. Animal studies have shown that manip­u­lating the micro­biome com­po­si­tion alle­vi­ates symp­toms of autoim­mune dis­eases such as rheuma­toid arthritis, which share many char­ac­ter­is­tics with PTLDS.

“We are going at Lyme dis­ease with every­thing we have,” says Lewis.

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Lola Lyme
Berichten: 377
Lid geworden op: Di 28 Okt 2014, 20:53

Re: Onderzoek persister cells

Berichtdoor Lola Lyme » Zo 11 Sep 2016, 09:32

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Laatst gewijzigd door Lola Lyme op Wo 04 Jul 2018, 15:50, 1 keer totaal gewijzigd.
♪♪♫♫ 'The soul always knows what to do to heal itself. The challenge is to silence the mind' ♫♫♪♪

Sproetje
Berichten: 3171
Lid geworden op: Di 28 Okt 2014, 20:33

Re: Onderzoek persister cells

Berichtdoor Sproetje » Zo 18 Sep 2016, 16:04

Ik denk dat persistentie iets anders is dan resistentie.

Belangrijk om te weten:
Persisters worden NIET gevormd door de aanwezigheid van antibioticum behandeling.

Importantly Persisters are not formed in response to antibiotic treatment Keren, I., et al. (2004). Persister cells and tolerance to antimicrobials. FEMS Microbiol. Lett. 230, 13–18

Het is bij Borrela dat er een paar overblijven in een soort van fase, zonder resistent te worden voor dezelfde antibioticum

Bij resistentie werkt het wat anders:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2937522/

A. baumannii is evolving rapidly.........
Erythromycin was an early example; introduced as an alternative to penicillin for the treatment of S. aureus in Boston City Hospital in the early 1950s, it was completely withdrawn after less than a year because 70% of all the S. aureus isolates were found to have become erythromycin resistant. The same was observed with chlortetracycline and chloramphenicol and, subsequently, with other antibiotics



Dan heb je een bacterie gecreeerd die totaal niet meer reageert op een bepaald soort antibioticum omdat de desbetreffende bacterie evolueert n.a.v. de ingebrachte ab (dat is dan een genetische ontwikkeling), waardoor resistentie tegen die soort ab optreedt, sommige bacterieen evolueren snel.
Zoals bv de stafykokken.

Maar als ze kunnen ontdekken hoe ze resistentie kunnen voorkomen, wordt het voor een resistente opportunist meteen minder makkelijk.
Laatst gewijzigd door Sproetje op Do 27 Jul 2017, 19:41, 2 keer totaal gewijzigd.


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