J. Makjanić

The onset of atherosclerotic lesion formation in hypercholesterolemic rabbits is delayed by iron depletion

The theory that iron may play a significant role in atherogenesis by promoting the formation of free radicals is controversial. Previous results using the new technique of nuclear microscopy showed a seven‐fold increase in iron concentrations within newly formed atherosclerotic lesions in hypercholesterolemic rabbits compared to healthy artery tissue. In a follow‐up time sequence study described here, we show that iron accumulation occurs at the onset of lesion formation. In addition, weekly bleeding decreases the iron uptake into the artery wall and delays the onset of atherogenesis. These results provide direct evidence for a key role of iron in initiating atherogenesis.

A Nuclear Microscopic Study of Elemental Changes in the Rat Hippocampus After Kainate-Induced Neuronal Injury

Abstract: The effect of intracerebroventricular kainate injection on the elemental composition of the hippocampus was studied in adult Wistar rats, at 1 day and 1, 2, 3, and 4 weeks postinjection, using a nuclear microscope. An increase in calcium concentration was observed on the injected side from 1 day postinjection. The increase peaked at 3 weeks postinjection, reaching a concentration of 18 times normal. Large numbers of glial cells but no neurons were observed in the lesioned CA fields at this time, suggesting that an increased calcium level was present in glial cells. This was confirmed by high‐resolution elemental maps of the lesioned areas, which showed very high intracellular calcium concentrations in almost all glial cells. It is possible that the high intracellular calcium level could activate calcium‐dependent enzymes, including calpain II and cytosolic phospholipase A2, shown to be expressed in reactive glial cells after kainate injections. In addition to calcium, an increase in iron content was also observed at the periphery of the glial scar at 4 weeks postinjection. Because free iron could catalyze the formation of free radicals, the late increase in iron content may be related to oxygen radical formation during neurodegeneration.

Absence of aluminium in neurofibrillary tangles in Alzheimer's disease

Using the new technique of nuclear microscopy, aluminium is not detected in pyramidal neurons in brain tissue from Alzheimers disease (AD) patients. The analytical technique of nuclear microscopy can simultaneously image and analyse features in unstained and untreated tissue sections. In tissue which had been previously subjected to conventional procedures such as fixation and osmication, aluminium was observed in both neurons and surrounding tissue. This result shows that the analysis of tissue prepared using conventional chemical techniques may produce contamination or elemental redistribution, and supports our previous investigations which implied that aluminium is not involved in the aetiology of AD. In addition, significant increases in iron, phosphorus and sulphur concentrations were noted between neurons from Alzheimer tissue and neurons from age-matched controls, and between the supporting Alzheimer tissue and supporting control tissue, implying an overall increase in these elements. No significant increase in calcium was observed between neurons from Alzheimer tissue and neurons from age-matched controls.

Determination of uranium in sea water by X-ray fluorescence spectroscopy

The X-ray spectrometric method for uranium determination in sea water is discussed. Two techniques of uranium enrichment are presented: (1) precipitation with the chelating agent ammonium-1-pyrrolidine dithiocarbamate (APDC) in the presence of iron(II) as a carrier and (2) complexation with APDC followed by adsorption on activated carbon. The best pH range and the other optimized conditions for uranium determination in sea water with both methods are reported.

Comparison of different modes of excitation in X-ray emission spectroscopy in the detection of trace elements in coal and coal ash

Abstract Three different modes of sample excitation in X-ray emission spectroscopy were used in trace element analysis of coal and coal ash: proton beam, Mo X-ray tube and radioactive sources 57Co and 109Cd. The results of analysis are presented and methods and their possibilities are compared in order to indicate the most appropriate technique for the particular purpose.

OPTIMIZATION OF XRFS FOR THE ANALYSIS OF TOXIC ELEMENTS AND HEAVY METALS IN COFFEE PRODUCTS

XRFS can be successfully used for routine on-line analysis of different agricultural products, for instance where food quality control is necessary. The optimization of the system for such purposes and the results obtained are shown on the example of the analysis of coffee.

Nuclear microscopy in Alzheimer’s disease

Abstract The elemental composition of the two types of brain lesions which characterise Alzheimer’s disease (AD) has been the subject of intense scrutiny over the last decade, ever since it was proposed that inorganic trace elements, particularly aluminium, might be implicated in the pathogenesis of the disease. The major evidence for this involvement was the detection of aluminium in the characteristic lesions of the AD brain; neuritic plaques and neurofibrillary tangles (NFTs). Using the powerful combination of Particle-Induced X-ray Emission (PIXE), Rutherford Backscattering Spectrometry (RBS) and Scanning Transmission Ion Microscopy (STIM), it is possible to image and analyse structures in brain sections without recourse to chemical staining. Previous results on elemental composition of senile plaques indicated the absence of aluminium at the 15 parts per million level. We have more recently focused on the analysis of neurofibrillary tangles (NFTs), destructive structural defects within neurons. Imaging and analysis of neurons in brain tissue presented a greater challenge due to the small dimensional size compared with the plaques. We describe the methodology and the results of imaging and analysing neurons in brain tissue sections using Nuclear Microscopy. Our results show that aluminium is not present in either neurons or surrounding tissue in unstained sections at the 20 ppm level, but can be observed in stained sections. We also report elemental concentrations showing significant elevations of phosphorus, sulphur, chlorine, iron and zinc.

NUCLEAR MICROSCOPY STUDY OF NEUROFIBRILLARY TANGLES IN ALZHEIMER'S DISEASE

Abstract The NUS nuclear microscope has been utilized to determine aluminium concentrations in normal and neurofibrillary-tangle-bearing neurons in brain tissue sections from Alzheimers patients. It was demonstrated that both neurons and neurofibrillary tangles can be identified by STIM in situ in thin tissue. High aluminium levels of up to 500 parts per million were found in tissue fixed with osmium tetroxide, with higher concentrations present in neurons than in surrounding tissue. Preliminary results on untreated freeze dried sections however have yielded an absence of aluminium down to the minimum detection limits of 20 ppm, implying that aluminium is an artifact introduced during sample preparation.

Comparison of particle and photon excited X-ray characteristic spectra applied to elemental analysis of hair samples

Abstract Two different modes of sample excitation have been used for elemental analysis of hair: PIXE (2.5 MeV protons) and XRF (Mo anode). The same samples were exposed to X-ray and proton beams. Difficulties in the interpretation of data in both methods arise from: energy loss or absorption of the incident beam, X-ray self-absorption, difficulties in the determination of sample mass, and lack of knowledge of the distributions of elements in hair samples. The influence of these effects in trace element analysis is discussed. An absorption model for XRF was developed.

Nuclear microscopy investigations into the role of iron in atherosclerosis

Abstract Using nuclear microscopy we have investigated elemental distributions and concentrations in aortic arch tissue sections from three groups of rabbits: (a) rabbits on normal diet (normal group), (b) rabbits on a high-cholesterol diet (control group), and (c) rabbits on a high-cholesterol diet and depleted in iron by weekly bleeding (test group). Rabbits in each group were sacrificed at 4-week time intervals, at 4, 8, 12 and 16 weeks. As early as 4 weeks, the aortic arches of control rabbits showed signs of fatty streaks and lesions, with a 2-fold average increase of iron concentration in the artery wall of cholesterol fed rabbits compared to the normal group. At 12 and 16 weeks the control group exhibited well-developed atherosclerotic lesions with an accompanying 3-fold increase in iron. The test group showed a significant reduction of lesion formation compared to the controls, and only after 12 weeks was an increase in iron concentration in the aortic arch observed. These findings show that controlled blood letting results in reduced uptake of iron by the artery wall and delayed atherosclerotic lesion formation. This correlation strongly suggests that iron has an important role in the aetiology of atherosclerosis.