Tagged: receptor

What do you do with a problem like Exenatide?

At 23:30 on the 3rd August 2017, the results of a phase II clinical trial investigating the use of a Glucagon-like peptide-1 receptor (GLP-1R) agonist called Exenatide (Bydureon) in Parkinson’s were published the Lancet journal website.

The findings of the study were very interesting.

And after years of failed trials, the Parkinson’s community finally had a drug that appeared to be ‘doing something’. Naturally these results got many in the Parkinson’s community very excited.

Over the last couple of weeks, further research related to this topic has been published. In today’s post we will review some of this new research and ask some important questions regarding how to move forward with these results.


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In 2012, the Golden Goose Award was awarded to Dr John Eng, an endocrinologist from the Bronx VA Hospital.

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Dr John Eng. Source: Health.USnews

The Award was created in 2012 to celebrate researchers whose seemingly odd or obscure federally funded research turned out to have a significant and positive impact on society.

And despite the name, it is a very serious award – past Nobel prize winners (such as Roger TsienDavid H. Hubel, and Torsten N. Wiesel) are among the awardees.

This week a research report was published in the journal Nature Medicine that expanded on the work of Dr Eng (some 25 years after his big discovery).

And it could be very important to the Parkinson’s community.

Sounds intriguing. What did Dr Eng do?

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Xenon: A bright light for dyskinesias?

A recent study published by French, British and Swiss researchers has grabbed the attention of some readers.

The report suggests that the inert/noble gas, Xenon, has powerful anti-dyskinetic properties in both mouse and primate models of Parkinson’s with L-DOPA-induced dyskinesias.

Dyskinesias are involuntary movements that can develop over time with prolonged used of L-DOPA treatments.

In today’s post, we will discuss what Xenon is, how it may be reducing dyskinesias, and we will consider some of the issues associated with using Xenon.


Dyskinesia. Source: JAMA Neurology

There is a normal course of events following a diagnosis of Parkinson’s.

Yes, I am grossly over-generalising, and no, I’m not talking from personal experience, but just go with me on this for the sake of discussion.

First comes the shock of the actual diagnosis. For many it is devastating news – an event that changes the course of their future. For others, however, the words ‘you have Parkinson’s‘ can provide a strange sense of relief that their current situation has a name and gives them something to focus on.

This initial phase is usually followed by the roller coaster of various emotions (including disbelief, sadness, anger, denial). It depends on each individual.

The emotional rollercoaster. Source: Asklatisha

And then comes the period during which many will try to familiarise themselves with their new situation. They will read books, search online for information, join Facebook groups (Click here for a good one), etc.

That search for information often leads to awareness of some of the realities of the condition.

And one potential reality that causes concern for many people (especially for people with early onset Parkinson’s) is dyskinesias.

What are dyskinesias?

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To B3 or not to B3, that is the question

The results of a recent clinical study for Parkinson’s conducted in Georgia (USA) has grabbed the attention of some readers.

The study involved Niacin (also known as nicotinic acid), which is a naturally occurring organic dietary compound and a form of vitamin B3.

The study was very small, but the researchers noticed something interesting in the blood of the participants: Niacin was apparently switching some of the immune cells from an inflammatory state to an anti-inflammatory state.

In today’s post, we will discuss what Niacin is, how it relates to Parkinson’s, and we will consider some of the issues with having too much niacin in your diet.


Source: Universal

It is one of the most common requests I get:

“Can you give an opinion on this supplement ____ or that vitamin ____ as a treatment for Parkinson’s?”

And I don’t like giving opinions, because (my standard disclosure) “I am not a clinician, just a research scientist. And even if i was a clinician, it would be unethical for me to comment as I am not familiar with each individual’s medical history. The best person to speak to is your personal doctor“.

But I also don’t like giving opinions because of a terrible fear that if I write anything remotely positive about anything remotely supplemental or vitamintal (is that a word?), a small portion of readers will rush off and gorge themselves on anything that sounds remotely similar to that supplement or vitamin.

So you will hopefully understand why I am hesitant to write this post.

But having said that, the recently published results of a small clinical study conducted in Augusta (Georgia, USA) are rather interesting.

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Is there NOP hope for Parkinson’s?

Please do not misread the title of this post!

Compounds targeting the Nociceptin receptor (or NOP) could provide the Parkinson’s community with novel treatment options in the not-too-distant future.

In pre-clinical models of Parkinson’s, compounds designed to block NOP have demonstrated neuroprotective properties, while drugs that stimulate NOP appear to be beneficial in reducing L-dopa induced dyskinesias. 

In today’s post we look at exactly what NOP is and what it does, we will review some of the Parkinson’s-based research that have been conducted so far, and we will look at what is happening in the clinic with regards to NOP-based treatments.


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Source: LUMS

On the surface of every cell in your body, there are lots of small proteins that are called receptors.

They are numerous and ubiquitous.

And they function act like a ‘light switch’ – allowing for certain biological processes to be initiated or inhibited. All a receptor requires to be activated (or blocked) is a chemical messenger – called a ligand – to come along and bind to it.

An example of a receptor on a cell. Source: Droualb

Each type of receptor has a particular structure, which is specific to certain shaped ligands (the chemical messenger I mentioned above). These ligands are floating around in the extracellular space (the world outside of the cell), having been released (or secreted) by other cells.

And this process represents one of the main methods by which cells communicate with each other.

By binding to a receptor, the ligand can either activate the receptor or alternatively block it. The activator ligands are called agonists, while the blockers are antagonists.

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Agonist vs antagonist. Source: Psychonautwiki

Many of the drugs we currently have available in the clinic function in this manner.

For example, with Parkinson’s medications, some people will be taking Pramipexole (‘Mirapex’ and ‘Sifrol’) or Apomorphine (‘Apokyn’) to treat their symptoms. These drugs are Dopamine agonists because they bind to the dopamine receptors, and help with dopamine-mediated functions (dopamine being one of the chemicals that is severely in the Parkinsonian brain). As you can see in the image below the blue dopamine agonists can bypass the dopamine production process (which is reduced in Parkinson’s) and bind directly to the dopamine receptors on the cells that are the intended targets of dopamine.

Source: Bocsci

There are also dopamine antagonists (such as Olanzapine or ‘Zyprexa’) which blocks dopamine receptors. These drugs are not very helpful to Parkinson’s, but dopamine antagonist are commonly prescribed for people with schizophrenia.

Are there other receptors of interest in Parkinson’s?

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Reduce your RAGE as you AGE

An Advanced Glycation Endproduct (or AGE) is a protein or lipid that has become glycated.

Glycation is a haphazard process that impairs the normal functioning of molecules. It occurs as a result of exposure to high amounts of sugar. These AGEs are present at above average levels in people with diabetes and various ageing-related disorders, including neurodegenerative conditionsAGEs have been shown to trigger signalling pathways within cells that are associated with both oxidative stress and inflammation, but also cell death.

RAGE (or receptor of AGEs) is a molecule in a cell membrane that becomes activated when it interacts with various AGEs. And this interaction mediates AGE-associated toxicity issues. Recently researchers found that that neurons carrying the Parkinson’s associated LRRK2 G2019S genetic variant are more sensitive to AGEs than neurons without the genetic variant. 

In today’s post we will look at what AGE and RAGE are, review the new LRRK2 research, and discuss how blocking RAGE could represent a future therapeutic approach for treating Parkinson’s.


The wonder of ageing. Source: Club-cleo

NOTE: Be warned, the reading of this post may get a bit confusing. We are going to be discussing ageing (as in the body getting old) as well as AGEing (the haphazard process processing of glycation). For better clarification, lower caps ‘age’ will refer to getting old, while capitalised ‘AGE’ will deal with that glycation process. I hope this helps.


Ageing means different things to different people.

For some people ageing means more years to add to your life and less activity. For others it means more medication and less hair. More wrinkles and less independence; more arthritis and less dignity; More candles, and less respect from that unruly younger generation; More… what’s that word I’m thinking of? (forgetfulness)… and what were we actually talking about?

Wisdom is supposed to come with age, but as the comedian/entertainer George Carlin once said “Age is a hell of a price to pay for wisdom”. I have to say though, that if I had ever met Mr Carlin, I would have suggested to him that I’m feeling rather ripped off!

George Carlin. Source: Thethornycroftdiatribe

Whether we like it or not, from the moment you are born, ageing is an inevitable part of our life. But this has not stopped some adventurous scientific souls from trying to understand the process, and even try to alter it in an attempt to help humans live longer.

Regardless of whether you agree with the idea of humans living longer than their specified use-by-date, some of this ageing-related research could have tremendous benefits for neurodegenerative conditions, like Parkinson’s.

What do we know about the biology of ageing?

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The mystery of caffeine

Here’s a good riddle for you:

Many epidemiological studies have suggested that coffee/caffeine consumption reduces one’s risk of developing Parkinson’s. Study after study has suggested that drinking coffee is beneficial.

Recently, however, Japanese researchers have discovered something really curious: people with Parkinson’s have reduced levels of caffeine in their blood compared to healthy controls… even when they have consumed the same amount of coffee. (???)

In today’s post we will look at what coffee is, review the results of this study, and try to understand what is going on.


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Kaldi the goat herder. Source: CoffeeCrossroads

Legend has it that in 800AD, a young Ethiopian goat herder named Kaldi noticed that his animals were “dancing”.

They had been eating some berries from a tree that Kaldi did not recognise, but being a plucky young fellow – and being fascinated by the merry behaviour of his four-legged friends – Kaldi naturally decided to eat some of the berries for himself.

The result: He became “the happiest herder in happy Arabia” (Source).

This amusing encounter was apparently how humans discovered coffee. It is most likely a fiction as the earliest credible accounts of coffee-consumption emerge from the 15th century in the Sufi shrines of Yemen, but since then coffee has gone on to become one of the most popular drinks in the world.

Silly question, but what exactly is coffee?

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The Acorda’s Tozadenant Phase III clinical trials

The biotech company Acorda Therapeutics Inc. yesterday announced that it was halting new recruitment for the phase III program of its drug Tozadenant (an oral adenosine A2a receptor antagonist).

In addition, participants currently enrolled in the trial will now have their blood monitoring conducted on a weekly basis. 

The initial report looks really bad (tragically five people have died), but does this tragic news mean that the drug should be disregarded?

In todays post, we will look at what adenosine A2a receptor antagonists are, how they may help with Parkinson’s, and discuss what has happened with this particular trial.


Dr Ron Cohen, CEO of Acorda. Source: EndpointNews

Founded in 1995, Acorda Therapeutics Ltd is a biotechnology company that is focused on developing therapies that restore function and improve the lives of people with neurological disorders, particularly Parkinson’s disease.

Earlier this year, they had positive results in their phase III clinical trial of Inbrija (formerly known as CVT-301 – Click here to read a previous post about this). They have subsequently filed a New Drug Application with the US Food and Drug Administration (FDA) to make this inhalable form of L-dopa available in the clinic, but the application has been delayed due to manufacturing concerns from the FDA (Click here to read more about this). These issues should be solvable – the company and the FDA are working together on these matters – and the product will hopefully be available in the new year.

So what was the news yesterday?

Acorda Therapeutics has another experimental product going through the clinical trial process for Parkinson’s disease.

It’s called Tozadenant.

Source: Focusbio

Tozadenant is an oral adenosine A2a receptor antagonist (and yes, we’ll discuss what all that means in a moment).

Yesterday Acorda Therapeutics Inc announced that they have halted new recruitment for their phase III clinical program. In addition the company is increasing the frequency of blood cell count monitoring (from monthly to weekly) for participants already enrolled in the company’s Phase 3 program of Tozadenant for Parkinson’s disease.

The Company took this action due to reports of cases of agranulocytosis.

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PACAP and a snail model of Parkinson’s

We are going to talk about a snail model of Parkinson’s disease. I kid you not.

Love them or hate them, recent research on snails is helping us to better understand a potential therapeutic target for Parkinson’s disease, called Pituitary adenylate cyclase-activating polypeptide (or PACAP).

In today’s post we will look at what PACAP is, outline the new snail research, and discuss what they mean for people living with Parkinson’s disease.


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The humble snail. Source: Warrenphotographic

In a recent post, I talked about a class of drugs called Dipeptidyl peptidase-4 (or DPP-4) inhibitors (Click here to read that post). DPP-4 is a ubiquitous enzyme (it is present on most cells in your body) that breaks down certain proteins.

In that post, I listed some of the proteins that DPP-4 targets – they include:

  • Gastrin-releasing peptide (GRP)
  • Glucagon
  • Glucagon-like peptide-1 (GLP-1)
  • Glucagon-like peptide-2 (GLP-2)
  • Granulocyte-macrophage colony-stimulating factor (GM-CSF)
  • GHRH and IGF-1
  • High-mobility group box 1 (HMGB1)
  • Macrophage-derived chemokine (MDC)
  • Macrophage inflammatory protein-1 α (MIP-1 α), chemokine (C-C motif) ligand 3-like 1 (CCL3L1), or LD78β
  • Pituitary adenylate cyclase-activating polypeptide (PACAP)
  • Neuropeptide Y (NPY)
  • Regulated on activation, normal T cell expressed and secreted (Rantes)
  • Stromal cell-derived factor-1 (SDF-1)
  • Substance P (SP)

Lots of interesting proteins with regards to Parkinson’s disease on this list, including GLP-1 which has been turned in the drug Exenatide (which has demonstrated positive effects in recent clinical trials for Parkinson’s disease – click here and here to read more about this). Another interesting protein on the list is ‘Granulocyte-macrophage colony-stimulating factor‘ (GM-CSF) which we have also discussed in a previous post (Click here to read that post). A synthetic version of GM-CSF (called Sargramostim) has recently been tested in a clinical trial of Parkinson’s disease in Nebraska, and the results of that Phase I trial have been very encouraging.

By treating people with DPP-4 inhibitors (also known as ‘gliptins’), one would be blocking the breaking down of these potentially beneficial proteins – increasing the general amount of GLP-1 and GMCSF that is floating around in the body.


EDITOR’S NOTE: DPP-4 inhibitors have not yet been clinically tested in Parkinson’s disease, and thus we have no idea if they are safe in people with this condition. They are being mentioned here purely as part of an academic discussion.


One protein on the list of DPP-4 targets above that we have not yet discussed is Pituitary adenylate cyclase-activating polypeptide (or PACAP).

And today we are going to have a look at it.

Why?

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A clever new Trk for Rasagiline

The protein Alpha Synuclein has long been considered the bad-boy of Parkinson’s disease research. Possibly one of the main villains in the whole scheme of things. 

New research suggests that it may be interfering with a neuroprotective pathway, leaving the affected cell more vulnerable to stress/toxins. But that same research has highlighted a novel beneficial feature of an old class of drugs: MAO-B inhibitors.

In today’s post we will outline the new research, discuss the results, and look at whether this new Trk warrants a re-think of MAO-B inhibitors.


The great Harry Houdini. Source: Wikipedia

I’m not sure about you, but I enjoy a good magic trick.

That exhilarating moment when you are left wondering just one thing: How do they do that?

(Seriously, at 4:40 a baguette comes out of thin air – how did he do that?)

Widely believed to have been one of the greatest magicians of all time (Source), Harry Houdini is still to this day revered among those who practise the ‘dark arts’.

Born Erik Weisz in Budapest (in 1874), Houdini arrived in the US in 1878. Fascinated with magic, in 1894, he launched his career as a professional magician and drew attention for his daring feats of escape. He renamed himself “Harry Houdini” – the first name being derived from his childhood nickname, “Ehrie,” and the last name paying homage to the great French magician Jean Eugène Robert-Houdin. In 1899, Houdini’s act caught the eye of Martin Beck, an entertainment manager, and from there the rest is history. Constantly upping the ante, his feats became bolder and more death defying.

And the crowds loved him.

From stage, he moved on to film – ultimately starting his own production company, Houdini Picture Corporation. In addition, he was a passionate debunker of psychics and mediums, his training in magic helping him to expose frauds (which turned him against his former friend Sir Arthur Conan Doyle, who believed deeply in spiritualism).

This is all very interesting, but what does any of it have to do with Parkinson’s?

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Dear FDA, this is bigly wrong…and you know it!

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Dopamine agonist treatments are associated with approximately 90% of hyper-sexuality and compulsive gambling cases that occur in people with Parkinson’s disease.

This issue does not affect everyone being treated with this class of drugs, but it is a problem that keeps popping up, with extremely damaging consequences for the affected people who gamble away their life’s saving or ruin their marriages/family life. 

The U.S. Food and Drug Administration (FDA) is yet to issue proper warning for this well recognised side-effect of dopamine agonists, and yet last week they gave clearance for the clinical testing of a new implantable device that will offer continuous delivery of dopamine agonist medication.

In today’s post, we will discuss what dopamine agonists are, the research regarding the impulsive behaviour associated with them, and why the healthcare regulators should acknowledge that there is a problem.


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Dopamine. Source: Wikimedia

Before we start talking about dopamine agonists, let’s start at the very beginning:

What is dopamine?

By the time a person is sitting in front of a neurologist and being told that they ‘have Parkinson’s disease’, they will have lost half the dopamine producing cells in an area of the brain called the midbrain.

Dopamine is a chemical is the brain that plays a role in many basic functions of the brain, such as motor co-ordination, reward, and memory. It works as a signalling molecule (or a neurotransmitter) – a way for brain cells to communicate with each other. Dopamine is released from brain cells that produce this chemical (not all brain cells do this), and it binds to target cells, initiating biological processes within those cells.

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Dopamine being released by one cell and binding to receptors on another. Source: Truelibido

Dopamine binds to target cells via five different receptors – that is to say, dopamine is released from one cell and can bind to one of five different receptors on the target cell (depending on which receptor is present). The receptor is analogous to a lock and dopamine is the key. When dopamine binds to a particular receptor it will allow something to happen in that cell. And this is how information from a dopamine neuron is passed or transmitted on to another cell.

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Dopamine acts like a key. Source: JourneywithParkinsons

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