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BACKGROUND: Phenylketonuria (PKU) is caused by a severe phenylalanine hydroxylase deficiency; the mainstay of treatment is a low-phenylalanine diet. A diet which is so restrictive is associated with a risk of nutritional deficiencies. We investigated plasma concentrations for 46 elements, including minerals and trace elements. METHODS: We enrolled 20 children and adolescents with PKU and 20 matched controls. Multi-elementary quantification was carried out by solution-based inductively coupled plasma atomic emission spectroscopy (ICP-AES) and ICP mass spectrometry (ICP-MS). RESULTS: With the exception of manganese and aluminium, no significant differences were found for element levels between PKU patients and controls. As a trend, manganese levels were lower in PKU patients than in control subjects (p < 0.05) but were within the reference range. There was a positive linear relationship between manganese and tyrosine levels in subjects with PKU (r(2) = 0.2295, p < 0.05). If detectable, potentially toxic elements were only identified in ultra-trace quantities in plasma samples of either group; aluminium levels were found to be slightly higher in PKU subjects than in controls (p < 0.01). CONCLUSION: The combination of ICP-AES and ICP-MS data is a useful diagnostic tool for element quantification at a high analytical rate and for monitoring bio-element status, e.g. in patients on a restrictive diet.

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Photon-induced proton and alpha particle production in tissue is estimated for the photon energy range from 3 to 28 MeV, using the authors' previously established methods. It is shown that charged particle emission exceeds neutron emission for energies greater than 11 MeV by a factor that reaches a maximum of 7.0 at 17 MeV. Due to uncertainties in the source data this maximum value should be regarded as indicative only. Above 17 MeV the neutron yield rises sharply and the ratio of charged particle emission to neutron emission declines to values of 3.0 and 1.7 at 20 and 28 MeV, respectively.

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Various nuclear analytical methods have been developed and applied to determine the elemental composition of calcified tissues (teeth and bones). Fluorine was determined by prompt gamma-activation analysis through the 19F(rho, alpha, gamma)16O reaction. Carbon was measured by activation analysis with 3He ions, and the technique of proton-induced x-ray emission (PIXE) was applied to simultaneously determine calcium, phosphorus, and trace elements in well-documented teeth. Dental hard tissues (enamel, dentine, cementum, and their junctions) and different parts of the same tissue were examined separately. With the use of a proton microprobe, we measured the surface distribution of fluorine and other elements on and around carious lesions on the enamel. The depth profiles of fluorine, and other elements were also measured right up to the amelodentin junction. We discuss the development of various nuclear techniques and their applications, mainly in the field of dental health and to some extent in the study of the role of lead in mental retardation. We do not mention other important areas of calcified tissue research where these techniques could play an important role (e.g., in accurate and nondestructive measurements of calcium, phosphorus, and other elements in small bone biopsies taken from patients with metabolic bone disorders). No suitable chemical method appears to be available that can provide accurate assessment of calcium, phosphorus, and other trace elements in small bone biopsies. Moreover, the nondestructive nature of the nuclear methods has an extra advantage in that the bone samples, which are normally rather small in quantity, subsequently can be used for histologic examination.

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Photoneutron yields from water, polyethylene, tissue substitute and CR-39 have been calculated for the photon energy range of 2 to 30 MeV, using a previously established method and photoneutron production data on hydrogen, carbon, nitrogen and oxygen. The rarer isotopes of the constituent elements of these compounds, namely 2H, 13C, 15N, 17O and 18O, have been taken into account and neutrons are shown to be produced for photon energies above 2.2 MeV, the (gamma, n) threshold for 2H. The data are useful for estimating neutron production in materials located in the vicinity of a megavoltage radiotherapy beam. Substances such as those considered here are often used as filtration, phantom or scattering material and as components of neutron dosimetry detectors. Photoneutrons produced in such materials may need to be taken into consideration when carrying out neutron dosimetry in the presence of photons in this energy range, especially when the neutron flux is several orders of magnitude less than that of the photons.

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Sometimes infusion pumps are used to deliver whole blood to patients. However, in doing so there is a potential for damage to red cells from mechanical stresses in the pump, resulting in haemolysis. In order to investigate the degree of haemolysis caused by different pumps and therefore their suitability for whole blood infusion, we compared the performances of commonly used volumetric pumps (AVI 400; IVAC 560; IVAC 631 and IMED 927) with different pumping mechanisms. Our results show that the maximum haemolysis (3.9 mg/100g) was caused by the IVAC 560 and the least (1.08 mg/100g) by the AVI 400.

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Various nuclear analytical methods have been developed and applied to determine the elemental composition of calcified tissues (teeth and bones). Fluorine was determined by prompt gamma activation analysis through the 19F(p, alpha gamma) 16O reaction. Carbon was measured by activation analysis with He-3 ions, and the technique of Proton-Induced X-ray Emission (PIXE) was applied to simultaneously determine Ca, P, and trace elements in well-documented teeth. Dental hard tissues: enamel, dentine, cementum, and their junctions, as well as different parts of the same tissue, were examined separately. Furthermore, using a Proton Microprobe, we measured the surface distribution of F and other elements on and around carious lesions on the enamel. The depth profiles of F, and other elements, were also measured right up to the amelodentin junction.

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A nuclear analytical method, involving activation with 3He ions, was developed to determine carbon content in human teeth with well-documented histories. The tooth samples were irradiated with 2.7-MeV3He particles at 50 nA intensity, and the activity of 14O induced through the reaction 12C(3He, n)14O, determined by counting the 2.31-MeV gammas. Different dental hard tissues were studied separately. A solid piece of silver steel, the carbon content of which was accurately determined by chemical means, was used as the standard. The carbon content in different teeth varied from 4-7%. The overall experimental accuracy was better than 4.5%.

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The total yield of photoneutrons from soft-tissue-equivalent material irradiated with bremsstrahlung of end-point energy from 6 to 28 MeV has been measured using the 35 MeV University of Melbourne Betatron and a 4 pi Halpern-type neutron detector. The results are compared with calculations based on the cross sections for neutron production of the constituent elements of tissue (H, C, N and O). It is shown that the less common isotopes of the constituent elements (2H, 13C, 15N, 17O, 18O) must be included to obtain agreement with the measured yields. The dose imparted to tissue by the photoneutrons is calculated for the energy range from 6 to 30 MeV and is compared with other available estimates. Further, the dose equivalent due to all photonuclear reactions in tissue is estimated for energies of 24 and 30 MeV.

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Sampling, storage, and preparation of biological material for analysis are some of the most important factors in the study of trace elements in biomedical fields. If due care is not given to these factors, the resulting data may often be meaningless, regardless of the analytical technique chosen for analysis. A survey of the data in the literature would support this view, in which wide differences in the trace element composition of biological tissues have been observed, and not all these differences are attributed to variations in the biological systems.In this paper, the following points are discussed in detail: (A) Sampling and Storage Sampling methods and program. Contamination of the sample during sampling and storage. Changes in the composition during storage. Various storage methods for solid and liquid samples. (B) Sample Preparation Drying and ashing. Wet digestion. Different methods for preparing samples of hard, semihard, and soft tissues, and of biological fluids.

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Various nondestructive ion beam analysis techniques have been developed and applied to study the concentrations of fluorine and other trace elements in calcified tissues.Fluorine has been determined by prompt gamma activation analysis through the F(ϱ,αγ)O reaction. This method is quick, convenient, and sensitive, and can also be applied to measure fluorine depth distribution nondestructively in teeth and bone samples. By the application of this technique, fluorine concentrations have been determined in a number of teeth with known histories and bones of experimental animals. Moreover, F-depth-distributions to 10-µm depths have also been obtained in a number of selected human and animal teeth.Carbon was measured by activation analysis with He-3 ions, and the technique of Proton-Induced X-ray Emission (PIXE) has been developed to simultaneously determine Ca, P, and trace elements in well-documented teeth. Dental hard tissues, i.e., enamel, dentine, cementum, and their junctions, as well as different parts of the same tissue, have been examined separately. A number of elements, Na, Mg, Al, P, Cl, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Sr, Br, Rb and Pb, have been determined in these dental tissues. The concentrations of some of these elements vary considerably in different teeth and in various parts of the same tooth.The special advantages of these nuclear techniques for studying metabolic bone diseases, renal diseases, and the effect of Pb on childrens' intelligence are discussed.

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There are some papers in the literature on the trace element contents of fetal livers of 20-wk gestation time and over. However, there is very little information on this subject for fetal livers of less than 20-wk gestation. We have initiated a program on the measurement of trace elements in fetal livers of 12-22-wk gestation, using thick-target X-ray fluorescence analysis.The liver samples were obtained from freshly aborted fetuses. After removing blood from the samples, they were chopped into small pieces and freeze dried. The resulting material was ground into fine powder and compressed into 3-mm thick pellets, with boric acid backing. A similar pellet was also made of NBS-Bovine Liver-which was used as the standard for calculating the absolute concentrations of different trace elements.The measurements were carried out using a commercial Wave-Length-Dispersive XRF-System. Different X-ray tubes were used for different sets of elements in order to maximize the detection sensitivity. The results are compared with those of fetal liver of longer gestation and adult livers.

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The effect of diabetes on trace elements concentration in blood of experimental animals has been studied by thin-target X-ray fluorescence analysis. Balb/C young adult mice, 6-8 wk old, were used in the study. About 100-200 µL venous blood was taken from each mouse for trace element analysis. The measurements were carried out on a commercial Wave-Length-Dispersive XRF System, with different X-ray tubes being used for maximizing the detection sensitivity of different groups of elements.Later on, the mice were made diabetic by an intravenous injection of Streptozotocin (250 mg/kg). Then, 2 and 3 wk after the injection, 100 µL of venous blood was drawn from each of the mice and analyzed for trace element concentration. In this way we were able to study the changes in blood trace elements caused by diabetes.The results and advantages of using experimental animals, under controlled conditions, to study trace element variations caused by different diseases, are discussed in the paper.

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In order to get some information on the possible causes of graying of hair, we have used the technique of X-ray fluorescence (XRF) analysis for comparing the trace element contents of natural color and gray hair from a number of subjects. The technique of XRF was preferred to other analytical methods for this kind of comparative studies since it appeared to be simple, convenient, quick, and contamination free.Natural color and gray hair from each subject were obtained from the same scalp region. The hair samples were washed in the recommended fashion. The natural color and gray hair from different subjects were mounted separately on hollow plastic cylindrical sample holders, assuring that the hair were parallel to, and not on top of one another. The samples were analyzed in a commercial wave length dispersive XRF system, with different X-ray tubes being used for obtaining maximum sensitivity for different elements. The scattered X-ray peak from each sample was also monitored and gave a measure of the sample volume being investigated. So far, hair samples from 10 subjects have been analyzed. Their results are presented in the paper, and advantages of XRF, for trace element analysis on hair are discussed.

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In order to investigate the reliability of the Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES) for trace element analysis of biological materials, we have carried out extensive investigations on human plasma, using an Applied Research Laboratory's ICP-AES. When we aspirated the untreated plasma into the spectrometer, we obtained unreliable and nonreproducible results. However, when we pretreated the plasma by wet digestion (to destroy all the organic material), we achieved reproducible and consistent results. It is, therefore, suggested that biological samples should be pretreated, preferably by wet digestion, before being aspirated into the ICP-AES for analysis.

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The dose equivalent due to photonuclear reactions within a patient irradiated with 24-MeV bremsstrahlung has been calculated to be about 1% of the photon dose. This is more than two times smaller than the previously accepted estimate.

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The energy spectra of secondary neutrons produced when bremsstrahlung of end-point energy in the range 10-30 MeV is incident on oxygen, carbon and nitrogen have been calculated. Photonuclear reactions of the type (gamma, n) and (gamma, pn)( have been included. The respective contributions of various nuclear reactions have been adjusted using the published values of experimentally determined cross-sections, or branching-ratios, where these are available. Where no such information exists in the literature, the values have been empirically estimated. Agreements has been obtained between the calculated photoneutron spectra from C, N and O at various energies and the available experimentally-measured spectra. The photoneutron spectra from C, N and O have been combined in the right proportion (C5H40O18N) to compute the spectra of secondary neutrons from tissue irradiated with bremsstrahlung of end-point energy from 10-30 MeV. Mean neutron energies and kerma factors for these spectra have been calculated.

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