Cutting edge minerals

By Kasia Patel
Published: Thursday, 03 January 2013

IM looks at speciality applications in the medical industry

Commonly known for their use in the pharmaceutical and vitamin industry, researchers are looking into new niche uses for minerals such helping in the fight against cancer, or prevention against Alzheimer’s disease. As surgeons and medical companies move away from metal to plastic implants, the role of minerals grows in surgical applications too.

Though the medical industry will unlikely be the main driver behind mineral production, the importance of minerals in medicine is undeniable as a niche and developing use for pure, high-grade minerals.

 
 Silicone is used as a coating for hypodermic
needles to relieve penetration and drag force


Alzheimer’s prevention

Lithium carbonate tablets as a medication have been used to treat a number of mental health issues including depression, mania and bipolar disorder, working to affect the levels and activity of certain chemicals in the brain.

Evidence has indicated that lithium may also be used to prevent Alzheimer’s disease, a progressive mental deterioration occurring in middle or old age, due to generalised degeneration of the brain.

A report published in 2007, Lithium and risk for Alzheimer’s disease in elderly patients with bipolar disorder, outlined that the prevalence of Alzheimer’s was significantly less in a group of elderly patients with bipolar disorder on continuous lithium treatment than in a similar group without lithium therapy.

The report discussed whether there is a possibility of lithium having a preventative effect against Alzheimer’s disease and if it might potentially prevent the disease through a prophylactic effect on mood disorders.

According to the study, the rate of dementia increased by 13% with every depressive disorder episode, and 6% for those with bipolar disorder. If lithium reduces the number of episodes, it might potentially be able to prevent dementia in this way.

Taking lithium also inhibits synthase kinase 3 (GSK-3) alpha and GSK-3 beta in the brain, another potential avenue which may contribute to the prevention of Alzheimer’s disease.

Dr E B Ilgren, consultant scientist and physician formerly of the University of Oxford, spoke to IM about the possibility of lithium being used as a preventative treatment for Alzheimer’s disease.

He noted that although some evidence indicates using lithium would be advantageous, so far no preventative studies have been carried out specifically for this purpose.

Ilgren’s joint paper, Environmental Lithium Exposure in the North of Chile outlines that: “We still know almost nothing about the effects of lithium on normal people particularly in terms of brain function,” and the risks of high doses of lithium must still be explored.

 

Four main issues relevant to the human risk assessment for lithium need to be addressed; the effects of lithium on reproduction; its effects on human development; repeated dose toxicity; and exposure related observations in humans.

Ilgren outlines that so far any trials to explore effects on development and reproductive toxicology have only been carried out on animals, which have no human relevance, while exposure related observations in humans have been limited, and existing data is not sufficient for evaluation.

The way forward then, Ilgren said, is to finish characterising the population in the north of Chile, which was historically heavily lithium loaded with no outward signs of lithium toxicity. These populations were studied forty years ago as part of a broader study, meaning that the names of participants and their historical lithium concentrations are available for study today.

“[We need to] examine them for evidence of individual and population based effects attributable to the long term, low dose environmental exposure demonstrating manifestations strongly suggestive of effects that would be due to lithium and its ability to reduce brain degeneration clinically, radiologically and pathologically,” Ilgren told IM.

Population characterisation is already underway, and Ilgren hopes that if enough funding comes through, it can be completed in the next two years.

“The next step then would be to identify periods of exposure critical to these attributable effects so one would know when to start preventative treatment and for how long,” he added.

Ilgren hopes that if clear evidence can be demonstrated that lithium is neuroprotective and helps to prevent the development of Alzheimer’s disease, it can start being used as a treatment in the next five to 10 years.

However he stressed that the treatment is not a certainty and that more research and trials are certainly needed before this small but important niche use for high grade lithium can be implemented.

Coatings and implants

Silicone is a durable synthetic polymer of silicon with carbon and oxygen that can be in a solid, liquid or gel form. It has numerous medical uses, such as in antacids, contact lenses, artificial joints, pacemakers and cosmetic implants. It is also used in polishes and lubricants, and for less obvious applications like equipment coating.

In August 2012, silicone technology company NuSil published a paper on the advantages of coating needles with six different coatings to relieve penetration and drag forces of needles.

The study compared penetration forces of both coated and uncoated needles to compare the effectiveness of the company’s needle coating materials in lowering the force needed to penetrate and pass through a substrate.

Hypodermic needles generally have rough surfaces which cause friction resulting in a certain level of damage to the skin and causing discomfort for patients.

Although the shape of needles themselves – tri-bevelled, meaning they have sloping edges, with an elliptical opening and an elongated tube – eases penetration, the metal itself still causes friction, which according to NuSil’s paper prevents a smooth, comfortable puncture.

MED-6613-2, the company’s silica-reinforced pigmented cured silicone elastomer was found to be the most effective coating in providing lubrication effects for needles, although coating the needles used for the study with any of the silica sample materials resulted in significantly lower drag forces than the uncoated control needle.

Nuclear protection and x-rays

The Tohoku 9.0 magnitude earthquake and resulting tsunami that struck Japan on 11 March 2011 was one of the most devastating events in the country’s history, claiming over 15,000 lives and causing a nuclear disaster which sparked panic buying of potassium iodide (KI) tablets.

The Centers for Disease Control and Prevention (CDC) explains that KI tablets are stable iodine in a medical form, which is needed by the body to make thyroid hormones, though most KI intake comes from the food we eat.

In the case of a nuclear disaster like that in Japan, radioactive iodine is potentially released into the air where it can be breathed in, or it can contaminate the local food or drink supply through which it can cause internal contamination if ingested.

Radioactive iodine absorbed by the thyroid can injure the gland, but taking KI tablets will cause the gland to absorb stable iodine instead, blocking the gland from absorbing any more iodine – radioactive or otherwise – for around 24 hours.

KI tablets however only work to protect the thyroid – they do not protect the rest of the body and cannot reverse damage already caused by radioactive iodine.

According to the CDC Guideline for Disinfection and Sterilization in Healthcare Facilities published in 2008, Iodine solutions can also be used as an antiseptic before a procedure, while iodophors, a combination of iodine and solubilising agent carrier, have been used as both antiseptics and disinfectants.

The guideline points to several reports which have documented that an iodophor demonstrates a faster bactericidal activity than a full strength iodine solution, although the reasoning behind this is unclear. The solutions work by penetrating cell walls of microorganisms quickly, causing a lethal effect by disrupting protein, nucleic acid structure and synthesis in a cell, thus killing the bacteria.

Another use for iodine in medicine is during certain types of x-rays used to diagnose urinary system problems.

X-ray beams, which produce images of the body’s internal structure, are absorbed in varying amounts depending on the density of the material being x-rayed. Bone for example shows up as white, while air in a person’s lungs would appear black.

During an intravenous urogram (IVU), a contrast medium is necessary to provide more detail on an x-ray image. In such cases iodine solution is usually injected into the veins, which then moves to the bladder and kidney, allowing for a greater detail on the subsequent x-ray image.

Bone substitution and growth

Hydroxyapatite (HA), is a naturally occurring mineral form of calcium and phosphorous with similar properties to the mineral element in human bones, and it is because of this similarity that it is often used as a coating for medical implants.

Biomedical coatings provider APS Materials Inc. is a provider of HA coatings for medical device coatings such as hip and knee replacements and dental implants, allowing for cement-less implants, promoting osseointegration between the bone and orthopaedic implants.

According to the company, one of the issues of cemented implants is that they can loosen over time, potentially generating wear debris, which can trigger an immune response in the human body as it is recognised as a foreign body.

“Many reports suggest that HA coatings precipitate faster bone fixation and a reduction of pain and recovery time for implant patients,” says APS.

“As time passes, dental and orthopaedic implants coated with HA show a greater success rate in terms of the overall function of the implant. HA coatings (...) are unique in that they are capable of connecting structurally and functionally with human bone,” the company adds.

HA and other calcium mixtures can also be injected or applied manually for use as bone substitute for voids or gaps in the skeletal system caused by previous surgery or trauma, for example in extremities, craniofacial, the spine and pelvis.

Fighting cancer

Part of the kaolin family, halloysite is a rare clay which has contributed to medical research as it has been used to target circulating tumour cells in the body.

Cancer metastasis is when a tumour spreads to different parts of the body via circulating tumour cells which are released into the bloodstream and flow to another part of the body where they stick to a surface (such as organs). Halloysite could provide the key to detection and eventual manipulation of these cancer cells.

“We have been developing some procedures to try and isolate and detect tumour cells in the blood stream,” Michael R. King, associate professor of biomedical engineering at Cornell University, US, told IM.

The detection of circulating cancer cells is difficult given their tiny proportion in a millilitre of blood in comparison to millions of white blood cells and billions of red blood cells, but they can be detected by creating surfaces that mimic the interior surface of blood cells which cancer cells adhere to in the body. The adhesion does not come from halloysite but instead from a group of proteins called selectins.

Halloysite’s benefit lies in that a layer of it applied to the created surface basically repels the numerous white blood cells that accumulate as the body’s immune system activates. In doing this, it greatly increases the purity of tumour cells in the sample and as such means that circulating tumour cells can be targeted with ease.

While this is not strictly a cancer cure, it would prevent the cancer from metastasising around the body and forming new cancers.

As halloysite does not allow the accumulation of white blood cells it could be used as biomaterial, having the potential of preventing the immune system from attacking the foreign body with a wide range of applications in the medical industry, including in preventing the body attacking implants.

Pharmaceuticals

Though some minerals, such as lithium to treat bipolar disorders and magnesia for an upset stomach, are used as a treatment, others function as a carrier for medicine in tablets, pills and syrups.

Talc, calcium carbonate, phosphate and kaolin all appear in medicines as a carrier or as a coating/lubricant. 

Overall, high value minerals in pharmaceuticals and medical applications are never going to be the big business drivers for the world’s largest miners due to their speciality applications and low volumes.

However, as new uses are explored and the medical industry evolves, minerals are being used in increasingly varied applications, offering for many producers a significant bonus if the company can provide a high quality product.