CURRENT NEWS AND BIOLAB TESTS  March 2004

An occasional series of brief comments by Dr John McLaren Howard, Laboratory Director, on medical and general news items together with Biolab tests that may be useful in the investigation of these areas of concern.

MERCURY SENSITIVITY. In performing lymphocyte sensitivity tests for mercury we have used a mix of organic mercury and inorganic mercury (0.5pg methyl mercury and 4.5pg inorganic mercury) as the probe. From the beginning of February we have separated these and are reporting the separate findings for each form of mercury. There is no need to change your requesting pattern as both will be included in any mercury sensitivity request without additional charge.

The main exposure source of inorganic mercury is dental amalgam and small amounts of (the even more toxic) organic mercury may result from bacterial methylation of inorganic mercury from amalgam or any other source. Inorganic mercury (salts) has also been used as a fungicide in specialised paints and pastes. Organic mercury compounds have been used as seed dressings and as powerful fungicides in some specialised paints. Organic mercury is also present in some deep-water fish (tuna and shark seem to be the most contaminated) and in shell-fish – especially from estuaries that drain industrial sites.

The major difference between a mercury sensitivity and mercury toxicity is that the sensitised person can have the symptoms of mercury toxicity on subsequent low-level exposure or from chronic exposure as occurs with dental amalgams.

STRONTIUM got a very bad reputation as strontium 90 – a dangerous radioactive isotope of this relatively low toxicity metal. 'Ordinary’ strontium is present at low levels in many food sources of calcium. There is no known danger from this. The problem with the very persistent (and man-made) strontium-90 is that it targets bone. That is, like ‘ordinary’ strontium, it follows calcium metabolic pathways in the body. Strontium-90 can promote malignancy within the bone and/or leukemia due to mutations in bone marrow. There is no reason to believe that ‘ordinary’ strontium causes any problems. However, strontium can be helpful in a diagnostic sense.

When bone is degraded excessively (increased bone resorption), urinary calcium excretion increases. Unfortunately, from a diagnostic point of view, urinary calcium mostly reflects dietary intake and that is highly variable. People at risk of osteoporosis are often prescribed supplemental calcium and that also increases urinary excretion. As strontium follows the calcium pathways in the body and concentrates in bone, any significant loss of calcium from bone is accompanied by increased strontium excretion.

Supplemental sources of calcium only rarely contain strontium and even when they do it is at very low levels (a few parts-per-million). Measuring urinary strontium can help to differentiate between dietary or supplemental calcium excretion and increased bone resorption. We measure strontium excretion within our full toxic elements scan. If strontium excretion is increased we will always check the calcium level in the same sample. Urinary strontium reference range is up to 150ug/g creatinine with a mean of 45.

Other markers of increased resorption of bone include a raised tartrate-resistant acid phosphatase in the serum and increases in urinary hydroxyproline and zinc. These tests form part of our osteoporosis profile.

BERYLLIUM is a metal that many people have never heard of yet it is used extensively in electronics, aircraft construction and the nuclear and armaments industries. In recent years it has found wide spread use in modifying the mechanical and thermal characteristics of alloys that are widely used in many products.

I believe that it has even found uses in some alloys used in dentistry. People who work with these alloys may be occupationally exposed but the risks of exposure are (again) increasing for all of us. I have included the word ‘again’ as beryllium was once used in fluorescent lighting tubes and breakage of these was a significant exposure source. For your safety and the safety of others, please do not break old fluorescent tubes. Your local recycling centre will dispose of them safely.

There is no doubt at all about the toxicity of beryllium but it has a worse side to its nature. Low levels of beryllium can lead to sensitivity to this element and re-exposure, even at very low levels, can result in so called chronic beryllium disease. This has been known since the 1940s but has recently been the subject of a cautionary and excellent review in the Lancet (Vol 363, Feb 7th 2004, pp 415-6).

The disease mainly affects the lungs but is quite frequently mistaken for sarcoidosis. For example, a study in 2003 demonstrated that 6% of patients diagnosed as having sarcoidosis actually had chronic beryllium disease. We have available a lymphocyte sensitivity test for beryllium although the beryllium-specific T-lymphocyte activation test may better reflect ongoing chronic beryllium disease.

Our test is useful for identifying those at risk of beryllium disease – already sensitised people who need to do all they can to avoid further contact with this metal. Current exposure is usually reflected in an increased urinary excretion of beryllium but it is notoriously difficult to detect at very low levels. Any beryllium detectable in our all-metals-in-urine screen would be significant either as a sensitising initial exposure or as a very real hazard to anyone who is already sensitised.

It is important to understand that very low level exposure is significant. In manufacturing plants that comply with the strictest regulations where air borne beryllium must not exceed 2ug/m3  there is still a significant incidence of disease (2 to 15% shown in various studies conducted between 1993 and 2001).

No one knows how many industrially exposed people have beryllium disease but estimates for the USA are in the region of 10s of thousands. I have not seen any estimates for the UK . There is even less information about non-industrial exposure. One has to assume that most cases of beryllium disease are misdiagnosed. Many doctors have not heard of it.

SPERM COUNTS and ADDITIONAL TESTS. 

We always include chromatin decondensation studies with sperm counts performed here. Those investigations follow the unfolding of the DNA from the sperm head by the use of phase-contrast microscopy. Using techniques originally developed in Sweden , we check for early unfolding of the DNA in conditions that mimic vaginal fluid and the cervical environment. Sperms that unfold their DNA at that stage will not be available for conception. We also check that the DNA does decondense when zinc is removed from the sperm heads. This is essential for conception.

Abnormalities of sperm motility are more likely to reflect problems with the mitochondrial enzymes that are the power-house for this process or structural abnormalities. Starting this month, we will perform, report and comment on six additional tests that relate to the mitochondrial enzymes and expand our comments on any structural abnormalities.

There is no immediate price increase for the sperm count but, in a few months time we may reassess this in the light of numbers of samples examined.

UNUNSUAL FORM OF GLUTATHIONE PEROXIDASE (GSH-PX). Dr Damien Downing has identified several patients with low selenium levels and poor GSH-PX activity where the selenium has corrected on supplementation but the GSH-PX has remained low. The usual next step of checking and, where necessary, correcting glutathione availability has not helped.

Working on the hypothesis that, in these patients, there is something different about the protein (enzyme) itself, I have performed a number of experiments to try to identify the cause of the problem. The most dramatic result was the discovery that the ‘abnormal’ enzyme has a molecular weight of 67kDA while that of the ‘normal’ enzyme is close to 90kDa. It took a long time for the penny to drop! 67 is 74.4% of 90 and GSH-PX is tetrameric (made up of four sub-units each with one seleno-cysteine group). 74% is close enough to ¾. Could the abnormal form of the enzyme consist of just three sub-units?

The tests we have been able to do support this finding but with one confounder. There are four, not three, selenium atoms associated with each molecule of the enzyme. I have not fully resolved this but experiments to date suggest that each of the sub-units has one of the expected seleno-cysteine groups and that there is one additional selenium atom associated with the molecule. This is almost certainly a seleno-methionine group.

I include this just for interest but it is worth noting that enzymes changed as significantly as this are unlikely to have full endogenous activity. That certainly seems to be the case in these patients.

ORGANOPHOSPHATE PESTICIDE – DNA ADDUCT. In December 2003 we identified a tetrachlorvinphos-DNA adduct. I believe that this is the first report of any organophosphate pesticide adduct to DNA. This fuels the debate about possible carcinogenic effects of OPs.

Some doctors now routinely request that pesticide screens are performed on needle-biopsy fat cell samples rather than serum. As expected, the results demonstrate much higher levels of organochlorine pesticides than we would see in the serum but, perhaps of more import, we are finding significant levels of some halogenated phenols and benzene derivatives that would be missed by just using serum.

Of even more significance, we have found a number of organophosphate pesticide residues in patients with no known recent exposure. OPs are rapidly cleared from the blood stream and rarely detected there. Even the urine metabolites are only detectable for a very limited period after exposure.

Taken together, the fat cell OP findings and the, admittedly only one so far, finding of an OP-DNA adduct advance the understanding of long-term affects from OP exposure. These findings need to be replicated in other laboratories and we clearly need more experience ourselves in this area but, at last, I think I do have something to offer the doctor or patient who wants to know whether past, or current low-level. OP exposure may be responsible for current symptoms.

THE ROUTINE! Most of the work we do in the laboratories here is not in the above category. Most of it is routine - routine to us even if not routinely available in most medical laboratories. I hope the above items will be of some interest to you but, as for most Biolab users, it is the routine tests that you are most likely to request.

If you need information about any of the tests we perform then the web site is an excellent source, we can send you a copy of the Biolab guide or a CD ROM that also contains data from various Biolab seminars. If you still cannot find what you need then do not hesitate in contacting a member of staff. What is routine to us may be new to you. We continually learn from the questions we are asked and the feedback you kindly provide.

Mark Howard, Biolab manager, maintains the web site and organises the distribution of the Guide and the CD ROM. Contact Mark if you need general information or for administrative queries. Contact a member of the lab staff for specific inquiries about an individual test or result.

YOU and YOUR PATIENTS are the most important components in all that happens at Biolab. Thank you for using our services, for your welcome feedback and (usually welcome?) challenging questions that help us to move forward.

With very best wishes from the Biolab staff.                                                         

Dr John McLaren-Howard.

If you require further details about these news items or or any further information about Biolab please contact us directly: info@biolab.co.uk