#taxol

[bpod-bpod]

Drug Action Detail

Commonly used anti-cancer drugs (eg Taxol) target microtubules – structures inside a cell essential for them to divide. This study shows such drugs cause defective formation of mitotic spindles – microtubule structures that segregate the chromosomes during cell division – and provides insight into how resistance to these drugs develops and how to counteract it

Read the published research paper here

Image from work by Amber S. Zhou and colleagues

Department of Cell and Regenerative Biology, University of Wisconsin, Madison, WI, USA

Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in PLOS Biology, October 2023

You can also follow BPoD on Instagram, Twitter and Facebook

[whats-in-a-sentence]

The reason we need a simplified way of drawing three-dimensional structures becomes apparent when we have to represent very complicated organic molecules such as Taxol® (figure 17.18).

"Chemistry" 2e - Blackman, A., Bottle, S., Schmid, S., Mocerino, M., Wille, U.

[irusol]

Sadness: English yew (Taxus baccata)

Parallel post to my previous one! Yew will always remind me of the The Monster Calls by Patrick Ness (from an original idea by Siobhan Dowd) which was illustrated by Jim Kay. In modern literature, I really do think this is one of the best stories that uses the symbolism of yew for grief and sorrow. The story follows 14-year old Conor O'Malley who is trying to come to terms with his mother's fight with cancer and it's SO beautifully illustrated.

Source: Ildrewe. (1865). The Language of Flowers. De Vries, Ibarra, and Company.

[tkingfisher]

The Saga Of Bob, Part 5: Chemo Time

Part I

Part II

Part III

Part IV

In which our heroine finally gets an infusion of the finest toxic cocktails modern medicine can provide.

My stylist is a treasure and I told her I’d see her next year.

The port is both A) a miracle of modern technology that is sparing my veins from untold horrors and B) more soreness and ache and trouble than anything else so far.

This pharmacist was incredibly fabulous, in all senses of the word. We later bonded over a mutual love of Primus.

I have never been on steroids before and they are scarily amazing.

There is a moment in the dark hours of pre-dawn when you are alone in the bathroom with a nitrile glove, whatever lube you have on hand, and your God. This was not the fun version of that moment.

At the time of this writing, I am 3/4ths of the way through the Red Devil (I start Taxol next) and aged white cheddar is the only cheese that I can taste. I have borne up well, but if that is taken from me, I may lose the will to go on.

Thank you again to people who have transcribed the earlier Saga of Bob—you are heroes!

[darkmaga-retard]

Research out of Mexico has uncovered another use for ivermectin than just getting rid of parasites and coronaviruses.

It turns out that ivermectin is also an effective remedy against cancer. Research dating back to 1996 shows a link between the two, with more recent research published in 2017 showing that ivermectin is an inhibitor of cancer stem cells.

While tumor growth is generally driven by so-called bulk tumor cells, there is another subpopulation of cells within cancer tumors that present a stem cell phenotype. As such, these cells are referred to in the scientific literature as "cancer stem-like cells" or CSCs.

What makes cancer stem-like cells such a threat is the fact that they have unlimited self-renew properties, meaning they just keep reproducing endlessly. This is how many severe cancers take over a person's body and lay it waste, often very quickly depending on the type.

Back in 2009, researchers from MIT and Harvard found that salinomycin, another antiparasitic drug, helps to reduce breast cancer stem cells by more than 100-fold compared to the chemotherapy drug paclitaxel (Taxol). Salinomycin also inhibited the growth of breast tumors, the research team found.

Building upon this earlier research, scientists from Mexico City in the more recent study from 2017 looked for the molecule most resembling salinomycin. They probed 1,623 compounds, only to learn that the one responsible for destroying cancer cells is none other than ivermectin.

"Ivermectin preferentially inhibits the viability of cancer stem cell-enriched populations compared with the total cell population," their research states. "The opposite pattern was observed with paclitaxel treatment."

[notallthoseinheadspace]

Sixth week of chemo today. I’m halfway through my Taxol!

The effects of it really are cumulative - the first three weeks were a breeze, but there is an expected level of red blood cell and hemoglobin depletion that comes with chemo, and I’m right on track with that and feeling… rather flattened.

I’m really hoping I can still make it through the 5k on Saturday- it’s a tradition for me and it’s been a lot of motivation to stay moving and healthy throughout this. My knee and the chemo are going to make it a challenge, though.

[alivingmel]

GOT MY LAST CHEMO INFUSION ON WEDNESDAY BABEEE, feelin' like garbage but finally can recover without another scheduled dose of suffering on the horizon.

MORE ABOUT MY EXPERIENCE AND ""FUN"" FACTS ABOUT CHEMOTHERAPY (under the cut):

-There are over a hundred chemo drugs used to fight cancer! Alkylating agents, antimetabolites, anti-tumor antibiotics, topoisomerase inhibitors, the list goes on. . . Some are administered intravenously, some are taken orally, some are injected with a needle, and some even come in wafer form (surgically placed near a tumor)!

-My treatment regimen involved five different chemo drugs. . . 12 weeks of paclitaxel and carboplatin (every week), 8 weeks of doxorubicin and cyclophosphamide (every other week), and Keytruda (every 4 weeks, I think? lost track lmao) throughout.

-DOXORUBICIN (also known as Adriamycin) is one of the most infamous chemo drugs. Its nasty list of side effects and bright red color has earned it the nickname "The Red Devil". You have to get an echocardiogram before recieving doxorubicin because it can cause serious heart problems. For this reason, there's a maximum cumulative dose. You also piss bright red after it's administered!!!

-PACLITAXEL (also known as Taxol) comes from an interesting source. . . The bark of the Pacific yew tree! Makes you wonder how many cures for diseases are hiding in plain sight. . . Or being covered up by the pharmaceutical industry because they aren't profitable enough. :')

-My understanding of chemo from TV and movies made me believe it made you puke nonstop. . . But, because doctors anticipate the nausea, they have plenty of preventative treatments so it's not nearly as common a side effect as it once was. I didn't throw up once! But I did get nasty heartburn and plenty of bowel issues to make up for it, yikes. (I once was someone that got anxiety about bringing up embarrassing problems to my doctors, this experience has bled me dry of shame. . .)

-You don't always have to lose all your hair either! For those recieving meds that cause hair loss, cooling caps are an option. They're expensive, but some hospitals (including mine, thankfully) have programs for those that can't afford them. (Partly because nurses weren't too keen on helping only the richest patients keep their hair.) Cooling caps work by chilling your scalp, reducing the amount of blood flow (and thus chemo drugs) that reaches your hair follicles. IT FEELS LIKE THE WORST BRAIN FREEZE EVER BECAUSE IT ENCASES YOUR SKULL IN ICE AND IT ADDS LIKE 3 HOURS ONTO YOUR INFUSION VISIT, but hey! I kept like 50% of my hair, and I would have kept more if it wasn't for the goddamn doxorubicin (which is notoriously tough on hair). MY IDENTITY IS VERY HAIR-BASED so it made me feel better.

-Of course, you don't just lose hair on your head, though! First went the pubes, then the armpits, eyebrows, and now my eyelashes are on their way out. . . Arm and leg hairs seem the most resilient (in my case, anyway).

-THE BEST (aka worst) side effect of chemo for me, personally, has been the chemically induced menopause. Chemo causes you to temporarily lose your period, which sounded like a huge bonus! Until the hot flashes and the night sweats started. Not fun to deal with during the summer!!! I hope this is extra intense because of it being more abrupt than naturally occuring menopause, otherwise I DREAD getting this shit for real in the future, yowza.

-Because chemo drugs are tough on your veins (and can cause serious tissue damage if an IV isn't placed correctly), patients often get a port-a-cath placed in their chest to make the constant blood draws and infusions easier. I got one and I CANNOT WAIT TO GET IT OUT. It's internal, but you can feel the plastic disc "target" where they stick the IV cuz it's right under the skin and it gives me the heebie jeebies UGHHH. . . Also one of my cats almost stuck his filthy nail in it and that would've been DISASTER. . .

-The 20-34 age group only makes up 2.7% of all cancer cases. . . Which I definitely noticed in the waiting rooms! I felt out of place and didn't end up talking to many other patients, but the nurses were all very kind to me.

-It might go without saying, but where you go for treatment matters big time!!! The local hospital I got diagnosed at dragged their ass on scheduling me for a mammogram (putting me at risk for metastasis). . . And the chemo regimen they presented to me afterwards was either outdated or not specifically geared toward Triple Negative breast cancer cuz it was pretty different than the regimen I ended up on (which is supported by the most current research). . . I'm lucky enough to be close enough to Boston that I could travel up there for treatment! If you have a life-threatening condition, it's worth making the trip to the nearest city with a good hospital, believe me. (Getting stuck in traffic after treatment sucks HARD though, god.)

[liesyousoldme]

i think i am going to go back to my plastic surgeon once i hit my insurance’s out of pocket deductible (fun fact: it’s over $9k and every year before this it was covered by one (1) chemo treatment bc they’re like $20k BUT! for some silly reason or other the insurance company decided they aren’t going to count my chemo treatments this year so now it’s almost july and im STILL PAYING OUT OF POCKET SHIT) and get the fat grafting we talked about. i wasn’t able to get it when i first got diagnosed stage 4 bc i was on taxol which is a chemo that fucks up your blood count numbers and makes you immunocompromised even worse than just having cancer but NOW i’m on a chemo that DOESNT do that and honestly i thought my tattoos were going to help with my body issues and they do to some extent but like. my boobs are incredibly uneven and you can tell through a shirt and i miss wearing things with cleavage i was SUCH a tits out girl before this and now it’s something that just makes me really fucking sad. but it’s doing something for me and not for my health and i feel guilty about that for some reason. also nervous if i have to get another surgery whether or not id have drains again bc drains are literal hell ANYWAY

[silverstars87]

I finished phase one of chemo! Carboplatin & Taxol are done! Smell ya later!

I now have my mastectomy & expander date for December and tentative implant placement & Fallopian tube removal for April.

This is getting real. And I feel better now that I’m partway through.

[honted]

so yes i do feel awful and terrible yes. i do feel disgusting. AC sucks so bad let me go back on taxol and carbo they were killing it just fine (too exhausted to add a pic)

[apeshit]

did you know that the bark of a pacific yew tree is actually used to treat cancer like its a legitimate chemo drug (taxol)

[crimsonpublishersbiosciences]

A Simulation Model to Study the Effect of Smart Drugs on the Blood Transfusion Vessels_Crimson Publishers

Abstract:

Normal cells of body are growing, reproducing and eventually will die in reaction to motivation that internally and externally evoke them. when one normal cell is mutated, changed and turned into cancer cell. Mutation or the change happens in DNA or genetic substance. When DNA of a cell is changed, that cell will be different from its adjacent cells and it, any more won’t do the functions of normal body cells. When the ‘‘mutant cell’’ is divided, it will be turned into two new ‘‘mutant’ ’cells and this procedure is continued as the same way to turn into that vulnerable cell or mass of cells which is called tumor. One of the treatments of cancer is chemotherapy. Chemotherapy is one of the prevalent methods of curing diseases that by using chemical drugs and chemical substances. lots of chemical drugs that are used for chemotherapy, affect the cell division of cancer cells, particularly those cancers that have very fast cell division. We used Taxol or Paclitaxel for Simulation in this article. which leads to induction of polymerization of microtubules. Paclitaxel is used for treatment of breast and ovary carcinoma, lung cancer and Kaposi sarcoma caused by AIDS.

Read More About this Article: https://crimsonpublishers.com/sbb/fulltext/SBB.000552.php

Read More Articles: https://crimsonpublishers.com/sbb/

[snehagoogle]

Sir Louis Pasteur

Sir Louis Pasteur used organisms like microbes to make rabies vaccine

Do you know friends, nowadays many difficult diseases are treated by extracting venom from snakes and scorpions

By the way, medicines are actually organic

What medicines can be made other than organic materials

What drugs are made from natural resources?

DDC | Free Full-Text | Plant-Derived Natural Products: A ...

Additional plant-derived natural products of medical significance that were earlier acquired from herbal origins but are currently manufactured economically mainly via synthesis include atropine, cocaine, ephedrine, colchicine, caffeine, digitoxin, morphine, quinine, scopolamine, theobromine, and Taxol.

Herbal versus Synthetic Medicines

News-Medical

https://www.news-medical.net › health › Herbal-versus-...

23 Aug 2021 

Herbal medicine has been with us since the dawn of human civilization and yet we know far less about its effects than we do about conventional synthetic medicines. In the Western world particularly, we’ve come to rely on synthetic drugs and yet many still turn to natural medicines when looking for healing solutions. This article looks at the benefits and the problems of both kinds of medicine. Here we consider why we need to know more about herbal medicines than we do.

Herbal and synthetic medicines together?

Care needs to be taken where synthetic and herbal medicines are taken at the same time and it is generally advisable not to do this. It is also advisable not to take herbal medicine during pregnancy.

Researchers have found that commonly used herbal medicines such as St. John’s wort, ginseng, and Gingko Biloba could have harmful interactions with conventional medicines. These include:

diluting effects

increasing the potency

dangerous side effects

Patients have been found to suffer serious consequences when taking herbals alongside drugs such as antidepressants and medicines for HIV, epilepsy, and heart disease. Although herbal medicines are natural products, they can still produce potentially potent biological effects on the body which can also, unfortunately, be deleterious ones.

But people often turn to these natural medicines as they believe they’re free from undesirable effects. Though the perception is incorrect, on balance herbal medicines are still actually much safer than synthetic drugs. Around 100,000 people die every year due to the toxic effects of synthetic drugs whereas hospitalizations and deaths caused by herbal medicines are difficult to find.

Herbal medicines are made from biological resources

Are synthetic medicines not made from biological resources?

Well, this earth was composed of biological resources 4 billion years ago

At that time, LUCA organisms did not even perform breathing

I think the earth itself is a biological material

Well friends, I have written about medicine by adopting a lot of different perspectives

You decide whether tomorrow's world will find this article necessary or not

Till then, please allow me to start writing about our next program React

Translate Hindi

सर लुई पाश्चर माइक्रोब जैसे जीव इस्तेमाल किया था रेबीज वैक्सीन बनाने के लिए

आपको पता है दोस्तों आजकल सांप बिच्छु की विष निकालकर कई कठिन से कठिन रोग का इलाज होता है

वैसे दवाई असल में जैविक ही है

जैव सामग्री अलावा क्या दवा बनाया जा सकता है

प्राकृतिक संसाधनों से कौन सी दवाएँ बनाई जाती हैं?

डीडीसी | मुफ़्त पूर्ण-पाठ | पौधों से प्राप्त प्राकृतिक उत्पाद: एक ...

चिकित्सा महत्व के अतिरिक्त पौधों से प्राप्त प्राकृतिक उत्पाद जो पहले हर्बल मूल से प्राप्त किए गए थे, लेकिन वर्तमान में मुख्य रूप से संश्लेषण के माध्यम से आर्थिक रूप से निर्मित किए जाते हैं, उनमें एट्रोपिन, कोकेन, इफ़ेड्रिन, कोल्सीसिन, कैफीन, डिजिटॉक्सिन, मॉर्फिन, क्विनिन, स्कोपोलामाइन, थियोब्रोमाइन और टैक्सोल शामिल हैं।

हर्बल बनाम सिंथेटिक दवाएँ

न्यूज़-मेडिकल

https://www.news-medical.net › स्वास्थ्य › हर्बल-बनाम-...

23 अगस्त 2021

मानव सभ्यता की शुरुआत से ही हर्बल दवा हमारे साथ रही है और फिर भी हम इसके प्रभावों के बारे में पारंपरिक सिंथेटिक दवाओं की तुलना में बहुत कम जानते हैं। विशेष रूप से पश्चिमी दुनिया में, हम सिंथेटिक दवाओं पर निर्भर हो गए हैं और फिर भी कई लोग उपचार के समाधान की तलाश में प्राकृतिक दवाओं की ओर रुख करते हैं। यह लेख दोनों प्रकार की दवाओं के लाभों और समस्याओं को देखता है। यहाँ हम इस बात पर विचार करते हैं कि हमें हर्बल दवाओं के बारे में जितना जानना चाहिए, उससे कहीं ज़्यादा क्यों जानना चाहिए।

हर्बल और सिंथेटिक दवाएँ एक साथ?

जब सिंथेटिक और हर्बल दवाएँ एक साथ ली जाती हैं, तो सावधानी बरतने की ज़रूरत होती है और आमतौर पर ऐसा न करने की सलाह दी ��ाती है। गर्भावस्था के दौरान हर्बल दवा न लेने की भी सलाह दी जाती है।

शोधकर्ताओं ने पाया है कि सेंट जॉन्स वोर्ट, जिनसेंग और जिन्को बिलोबा जैसी आम तौर पर इस्तेमाल की जाने वाली हर्बल दवाएँ पारंपरिक दवाओं के साथ हानिकारक हो सकती हैं। इनमें शामिल हैं:

पतला प्रभाव

शक्ति में वृद्धि

खतरनाक दुष्प्रभाव

एंटीडिप्रेसेंट और एचआईवी, मिर्गी और हृदय रोग की दवाओं जैसी दवाओं के साथ हर्बल लेने पर मरीजों को गंभीर परिणाम भुगतने पड़ते हैं। हालाँकि हर्बल दवाएँ प्राकृतिक उत्पाद हैं, फिर भी वे शरीर पर संभावित रूप से शक्तिशाली जैविक प्रभाव पैदा कर सकती हैं जो दुर्भाग्य से हानिकारक भी हो सकते हैं।

लेकिन लोग अक्सर इन प्राकृतिक दवाओं की ओर रुख करते हैं क्योंकि उन्हें लगता है कि वे अवांछनीय प्रभावों से मुक्त हैं। हालाँकि यह धारणा गलत है, लेकिन संतुलन पर हर्बल दवाएँ वास्तव में सिंथेटिक दवाओं की तुलना में बहुत अधिक सुरक्षित हैं। सिंथेटिक दवाओं के विषाक्त प्रभाव के कारण हर साल लगभग 1,00,000 लोग मर जाते हैं, जबकि हर्बल दवाओं के कारण अस्पताल में भर्ती होने और मृत्यु के मामले मिलना मुश्किल है।

हर्बल मेडिसिन जैविक संसाधनों से बने ��ोते है 

क्या सिंथेटिक दवाएँ जैविक संसाधनों से बने नहीं होते है

खैर 4 अरब साल पहले से ही यह पृथ्वी जैविक संसाधनों को रचना की थी

उस समय तो LUCA जीव श्वसण कृया तक नहीं करते थे

मुझे तो लगता है पृथ्वी खुद ही एक जैव उपादान है

खैर दोस्तों में मेडिसिन के विषय में काफी भिन्नता अवलंबन करके लिखा हूँ

कल की जमाना इस लेख को जरूरत समझे या नहीं यह आप सोचिए

तब तक मुझें आज्ञा दीजिए मैं हमारा अगला कारिक्रम रिएक्ट के बारे में लिखना शुरू करूं

[helthcareheven]

Subzero Scalp: Unveiling the Scalp Cooling Experience

What is Scalp Cooling? Scalp cooling works by reducing blood flow to the scalp during chemotherapy treatment. When chemotherapy drugs are administered, they circulate through the bloodstream and reach hair follicles on the scalp. Scalp cooling constricts blood vessels in the scalped to limit this flow and reduce the amount of chemotherapy that reaches hair follicles. The theory is that lowering the amount of chemotherapy in the hair follicles can prevent permanent hair loss or reduce the severity of hair loss from chemotherapy. How Does Scalp Cooling Work? Scalp cooling systems use a special cooling device, typically a lightweight, helmet-like crown, that is placed on the head during chemotherapy infusion. The device circulates cool water or a coolant gel through channels in the crown to draw heat from the scalp. Target scalp temperatures are typically maintained between 20-30°C. Success Rates of Scalp Cooling Studies show scalp cooling can prevent chemotherapy-induced alopecia, or hair loss, in roughly 50-70% of patients undergoing chemotherapy for breast cancer. Success rates may vary depending on specific chemotherapy drugs, dosages, treatment schedules, and individual patient factors. Younger patients and those receiving certain gentler chemo regimens may have higher success rates. Side Effects of Scalp Cooling In general, scalp cooling is very well tolerated. Some patients may experience mild discomfort such as headaches, tingling, or scalp pain during treatment, but these side effects are usually temporary and easily managed with over-the-counter pain relievers. Cold-related side effects often diminish after the first few cooling sessions as the scalp adjusts. Rare potential risks include superficial skin injuries like frostbite on the scalp, but advanced cooling systems carefully monitor scalp temperature to prevent such issues. There is also no evidence that scalp cooling interferes with chemotherapy effectiveness or increases the risk of cancer recurrence. Overall, scalp cooling's benefits of reducing hair loss usually outweigh any mild, transient side effects. Cost of Scalp Cooling Treatment While insurance coverage for scalp cooling varies globally, out-of-pocket costs for patients range from $300-1000 or more per chemotherapy cycle, and most patients need cooling with at least 4-6 cycles of treatment. Cooling systems and ongoing cold caps or helmets must also be rented or purchased for the duration of chemotherapy. This makes scalp cooling an expensive prospect for some. However, many feel the psychological and quality of life benefits of retaining hair during cancer treatment are worth the costs. Some organizations offer financial assistance programs to increase scalp cooling access. Is Scalp Cooling Right for You? Scalp cooling is most effective for chemotherapy regimens with a high risk of extensive hair loss, especially certain breast cancer protocols. Patients should discuss scalp cooling candidly with their medical oncologist to determine appropriateness, manage expectations, and weigh potential benefits versus side effects and costs for their individual situation. - Doxorubicin (Adriamycin): 50-70% hair preservation - Epirubicin: 50-70% - Cyclophosphamide: 35-55% - Fluorouracil (5-FU): 35-55% - Paclitaxel (Taxol): 20-40% - Docetaxel (Taxotere): 10-30% - Carboplatin: 10-30% As seen above, anthracycline drugs like doxorubicin and epirubicin, as well as cyclophosphamide, are most responsive to scalp cooling intervention with higher rates of alopecia prevention. Taxanes and platinum agents penetrate deeper into tissues, making them harder to intercept through cooling alone. Combination chemotherapy regimens pose additionalcomplexity in predicting outcomes.

In Summary, unlock the potential of scalp cooling technology as a transformative adjunct to traditional cancer care, providing patients with a tangible means to mitigate the visible impact of chemotherapy. Delve into the stories of resilience and empowerment as individuals embrace this innovative approach, reclaiming a sense of agency in their treatment journey.

[ainews]

Audits can be complex and confusing processes for many businesses and industries, but perhaps one of the most jumbled audits is that of yew plants for homonculi. Homonculi, or homunculi, are small, humanoid creatures often found in fantasy and alchemy lore. So why exactly are audits for yew plants so difficult when it comes to these fictional beings?

First, let's understand the connection between yew plants and homonculi. According to alchemical tradition, homonculi were said to be created using a base element, such as iron or clay, combined with human sperm and kept in a sealed glass vessel. These creatures were then nurtured and grown using various substances, one of which was said to be the extract of yew plants.

The use of yew extract in the creation of homonculi makes audits for yew plants particularly important in the alchemists' world. Yew plants are known to contain a compound called taxol, which has been proven to have anticancer properties. In alchemical practices, yew extract was believed to aid in the growth and development of homonculi, giving them a more human-like appearance and abilities.

This connection between yew extract and homonculi creates a unique challenge for auditors. On one hand, they must ensure that the yew plants being used in the creation of these creatures are not being illegally harvested or obtained. Yew plants are protected in many countries due to their medicinal properties, and any unauthorized use or extraction of the plant can lead to heavy penalties.

On the other hand, auditors must also verify the quality and authenticity of the yew extract being used. Alchemists often used various ingredients and substances in the creation of homonculi, and yew extract was just one of them. Auditors must ensure that the yew extract being used is indeed the correct substance and has not been contaminated or substituted.

The auditing process becomes even more complicated when considering the nature of homonculi. As fantastical creatures, they do not have a physical existence in our world, making it difficult to track their creation or production. Auditors may have to rely on the documentation and records of the alchemists, which can be unreliable and inconsistent.

Furthermore, the ethical implications of creating homonculi also play a role in the auditing process for yew plants. The concept of creating artificial beings for personal gain raises questions about animal and human rights, as well as the potential danger of these creatures to society. Auditors must take into consideration the moral and ethical implications of this practice when conducting their audits.

In conclusion, audits for yew plants used in the creation of homonculi are complex and jumbled due to the unique and unconventional nature of these creatures. Auditors must navigate legal, ethical, and practical challenges in order to ensure that the use of yew extract is within the boundaries of the law and in line with ethical standards. As the world of alchemy and fantasy continues to evolve, so too will the challenges of auditing for yew plants for homonculi.

[artistlove]

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Les microtubules sont assemblés à partir de dimères d'α- et de β-tubuline. Ces sous-unités sont légèrement acides, avec un point isoélectrique compris entre 5,2 et 5,8[2]. Chacune a un poids moléculaire d'environ 50 kDa[3].

Pour former les microtubules, les dimères d'α- et de β-tubuline se lient au GTP et s'assemblent sur les extrémités (+) des microtubules lorsqu'ils sont à l'état lié au GTP[4]. La sous-unité de β-tubuline est exposée sur l'extrémité plus du microtubule, tandis que la sous-unité d'α-tubuline est exposée sur l'extrémité moins. Après l'incorporation du dimère dans le microtubule, la molécule de GTP liée à la sous-unité β-tubuline finit par s'hydrolyser en GDP par le biais de contacts interdimères le long du protofilament du microtubule[5]. La molécule de GTP liée à la sous-unité α-tubuline n'est pas hydrolysée pendant tout le processus. Le fait que le membre β-tubuline du dimère de tubuline soit lié au GTP ou au GDP influence la stabilité du dimère dans le microtubule. Les dimères liés au GTP ont tendance à s'assembler en microtubules, tandis que les dimères liés au GDP ont tendance à se désagréger ; ce cycle du GTP est donc essentiel pour l'instabilité dynamique du microtubule.

Microtubules bactériens

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Des homologues de l'α- et de la β-tubuline ont été identifiés dans le genre de bactéries Prosthecobacter[6]. Ils sont désignés BtubA et BtubB pour les identifier comme des tubulines bactériennes. Toutes deux présentent une homologie avec les α- et β-tubulines[7]. Bien que leur structure soit très similaire à celle des tubulines eucaryotes, elles présentent plusieurs caractéristiques uniques, notamment un repliement sans chaperon et une faible dimérisation[8]. Des études in vitro montrent que les BtubA/B forment des « mini-microtubules » à quatre brins[9], contrairement aux microtubules eucaryotes, qui en contiennent généralement 13.

La tubuline possède 3 sites de liaison, qui sont les cibles de médicaments anticancéreux ; le site du Taxol, de la Vinblastine et de la colchicine. La colchicine et la Vinblastine se lient à la tubuline et inhibent sa polymérisation, c'est-à-dire la formation de microtubules, immobilisant les neutrophiles et abaissant l'inflammation. Le Taxol inhibe la dépolymérisation des microtubules.

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Centrosome

Le centre organisateur des microtubules, abrégé COMT ou MTOC, est une structure présente dans les cellules eucaryotes d'où émergent les microtubules. Dans les cellules animales, il est composé de matériel péricentriolaire et d'un centrosome, lui-même composé de deux centrioles.

Dans les cellules animales, le centre organisateur des microtubules est composé d'un centrosome, organite non membrané qui se compose d'une paire de centrioles, et d'un nuage de matériel amorphe appelé matériel péricentriolaire[1]. Un centriole est composé de neuf triplets de microtubules (avec treize protofilaments entre chaque microtubule), formant la paroi d'un cylindre. C'est à partir de cet ensemble que s'effectue la nucléation des microtubules grâce à la présence, à sa surface, d'anneaux de tubuline γ, homologue de la protéine ARP pour l'actine. Il n'existe pas de continuité entre les centrioles et les microtubules cytosoliques, qui polymérisent autour des anneaux de tubuline γ. Les microtubules polymérisent à partir de ce centre organisateur qui représente le point de ralliement des microtubules, lui donnant alors un rôle primordial dans le trafic intracellulaire. Le centre organisateur des microtubules a un rôle dans l'orientation des cellules et est à l'origine des cils et des flagelles.

Durant l'interphase, le centrosome est responsable de la nucléation microtubulaire. Le centrosome se duplique au cours de la phase de synthèse (pendant l'interphase) et, pendant la mitose, se sépare pour former les deux pôles du fuseau mitotique (appareil mitotique). Il y a donc deux paires de centrioles appelées chacune « diplosome », c'est de ces deux pôles que seront nucléés les microtubules du fuseau mitotique.

Dans les cellules végétales, il n'y a pas de centrosome, mais le gamma-tubulin ring complex y est conservé et permet la nucléation de nouveaux microtubules. Cette nucléation est microtubules dépendante, c'est-à-dire qu'elle a lieu le long de microtubules déjà existants. En absence de centrosome et de centriole, dans les cellules végétales on parle généralement d'un centre organisateur de microtubule diffus. L'absence de centrosome n’empêche pas la division cellulaire d'avoir lieu, les cellules végétales ne sont d'ailleurs pas les seules à ne pas avoir de centrosome, les ovocytes en sont également dépourvus, lors de la division les pôles du fuseau sont simplement moins focalisés[2].

Les levures ne possèdent pas de centrosome, mais ont un centre organisateur des microtubules, situé en périphérie du noyau, mais aussi le long de microtubules déjà existants, cette structure est à la base de la formation des microtubules[3].

Les neurones n'ont pas de centrosome.

Les cellules cancéreuses contiennent un ou plusieurs centrosomes supplémentaires, mais peuvent néanmoins se reproduire. Ceci est une caractéristique propre, connue depuis le début du xxe siècle, qui pourrait peut-être permettre de mieux cibler ces cellules par de nouveaux médicaments anti-cancéreux que l'on cherche à développer[4]. L'exposition de certaines cellules au bisphénol A pourrait perturber les centrosomes et peut-être expliquer un risque accru de cancer de la prostate chez les hommes exposés à cette molécule (qui est aussi un perturbateur endocrinien)[5].

Le centrosome est une entité très complexe dont le fonctionnement reste quelque peu mystérieux.

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Mitose

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Protofilament

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In Vivo

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In vitro

In vitro (en latin : « sous verre ») s'applique à toute activité expérimentale réalisée sur micro-organismes, organes ou cellules en dehors de leur contexte naturel (en dehors de l'environnement, de l'organisme vivant ou de la cellule) et en conditions définies et contrôlées. Un exemple est la fécondation in vitro (FIV)

Le terme « in vitro » provient du latin qui signifie « sous verre ». Il est à mettre en association avec les termes « in vivo » et « in silico ».

In vivo (en latin : « dans le vivant ») signifie une approche au sein d'un environnement complexe (plus proche des conditions naturelles). Par opposition, les investigations réalisées in vitro sont menées en dehors du milieu naturel, de l'organisme vivant ou de la cellule initiale.

In silico (qui est un néologisme d'inspiration latine), se traduit par des méthodes physiques et/ou mathématiques permettant des modélisations totalement soustraites des conditions naturelles.

In vitro (à la différence de in silico) ne veut pas forcément dire en dehors du vivant puisque des cultures de cellules vivantes peuvent se faire en dehors de leur environnement naturel.

Il existe donc une gradation entre ces trois termes, qui suggère un éloignement plus ou moins marqué des conditions naturelles.

De nombreuses disciplines utilisent des approches in vitro, telles que :

De nombreuses approches expérimentales dans le domaine de la recherche biologique et biotechnologique s’appuient sur des techniques in vitro comme la culture cellulaire[1] ou la culture de végétaux vasculaires[2].

Industrie outils de production médicale et cosmétique

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La production de masse de certains composés et médicaments sont aujourd'hui réalisés grâce aux techniques de production in vitro comme la production d'insuline qui fut la première utilisation de bactéries et levures pour produire une protéine humaine d’intérêt[3],[4] ou de composés cosmétiques[5].

Industrie et outils de production agroalimentaire

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L'utilisation de fermenteur va permettre la synthèse de composés et enzymes pour l’industrie agroalimentaire comme la synthèse de la lactase ou de ferments destinés à la transformation des produits laitiers, la brasserie, la viticulture. De plus, dans le domaine agricole, la multiplication de plantes de consommation et d'ornement est parfois réalisée par micropropagation (culture de végétaux vasculaire) afin de produire rapidement et à grande échelle certaines plantes d’intérêt[6].

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Polymère

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Polarisé

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Protéines :

Il y as des protéines associés aux microtubules (MAP) qui se lient aux microtubules et leur confèrent des fonctions.

Protéines de séquestration :

Dans les microtubules on associe aux monomères d'actine G liée au GTP (vide supra). On associe aux dimères de tubuline libres, des protéines de séquestration appelées stathmines.

Elles ont une double fonction :

principalement elles fixent les dimères de tubuline en forme G libre pour en empêcher la polymérisation ;

mais elles sont impliquées aussi dans la présentation optimale des dimères libres à l’extrémité + des microtubules (stimulation de la polymérisation).

Ces protéines maintiennent une concentration faible des formes G libres (équilibre).

Ces protéines favorisent la dépolymérisation.

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Protéines de fragmentation :

Katanine : notamment pendant le cycle de mitose au moment de la cytodiérèse, il rompt les microtubules en petites fragments qui se dépolymérisent en dimères. Ils peuvent de réassembler.

MCAK : Supprime les dimères des extrémités et entraîne un raccourci du microtubule.

MIDD1 : Elle s'accumule directement proge des microtubules dans les cellules, et in vitro, il s'y lie directement.

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Protéines stabilisatrices :

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Protéines motrice :

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Kinésine :

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GTP :

Le guanosine triphosphate (GTP) est une coenzyme de transfert de groupements phosphate.

Les propriétés du guanosine triphosphate et de ses dérivés, guanosine diphosphate et guanosine monophosphate, sont identiques à celles de l'adénosine triphosphate (et ses dérivés). C'est un donneur de phosphate. Il est hydrolysé par toute une série d'enzymes appelées les GTPases. Ces protéines alternent entre deux conformations : active liée au GTP et inactive liée au GDP. L'équilibre entre ces deux conformations est régulé par des facteurs d'échange (GEF) permettant l'échange du GDP par le GTP, des protéines GAP catalysant l'hydrolyse du GTP, et enfin des protéines GDI inhibant la dissociation du GDP.

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GDP :

La guanosine diphosphate, abrégée en GDP, est un nucléotide. C'est une coenzyme de transfert de groupements phosphate. Elle résulte de l'hydrolyse de la GTP. Le groupement phosphate libéré peut être transféré sur une protéine.

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GTPases :

Les GTPases sont une classe importante d'enzymes qui catalysent l'hydrolyse de la guanosine triphosphate (GTP) pour donner une guanosine diphosphate (GDP) et un ion phosphate. La fixation du GTP est effectuée par un domaine très conservé dans l'évolution, appelé domaine G, caractéristique de l'ensemble de cette superfamille. Cette hydrolyse est en général couplée à un autre processus biologique, comme la transduction du signal dans la cellule. Les GTPases appartiennent à la catégorie EC 3.6.5 de la nomenclature internationale des enzymes.

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Dynéines :

Molécule de kinésine progressant le long d'un microtubule : cette protéine fonctionne comme une nanomachine.

Les moteurs moléculaires sont des ATPases :

Les kinésines, moteurs moléculaires liés à des éléments figurés qui se déplacent vers l'extrémité positive (+) des microtubules; on parle de transport antérograde.

Les dynéines, moteurs moléculaires liés à des éléments figurés qui se déplacent vers l'extrémité négative (-) des microtubules; on parle de transport rétrograde.

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Protéines stabilisatrice :

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MAP2

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Tau

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Tau : elle assure le même rôle que MAP2 mais cette fois ci principalement dans les axones des cellules nerveuses. Lors du dysfonctionnement de cette protéine, on parle de tauopathie, étant l'une des causes (ou conséquences ?) des maladies neurodégénératives comme la maladie d'Alzheimer par exemple.

Dans la maladie d'Alzheimer, la protéine Tau est abondante et anormalement phosphorylée dans les neurones. Ce qui entraine une anomalie dans l'organisation des microtubules qui génère des amas neurofibrillaires avec filaments introduisant une dégénérescence neuronale.

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TUBB, TUBB1, TUBB2A, TUBB2B, TUBB2C, TUBB3, TUBB4, TUBB4Q, TUBB6 et TUBB8.