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K G Malmqvist

Publications and source records attributed to K G Malmqvist.

16 recordsLinked to original sources
PubMed1996

Pixe analysis of pathological skin with special reference to psoriasis and atopic dry skin.

The nuclear microprobe is used for element analysis of human skin cross sections, providing new insight into the physiology of normal and pathological conditions. Special interest is focused on trace elements as they work as secondary messengers or regulatory substances. The distribution of ions in normal tissues serves as reference for pathological changes. Calcium (Ca2+) is assumed to take an important role in the differentiation process of the epidermis. This paper presents new data on elemental and trace elemental distributions in skin. Samples are prepared from skin biopsies obtained from patients with skin disorder and from individuals with no records of skin disorder serving as controls. Using the nuclear microprobe, both elemental maps and quantitative depth profiles are obtained. Previous findings of abnormal Fe distribution in psoriatic skin are confirmed, and new observations of altered Zn and Ca profiles in atopic skin are reported. The relation to possible physiological/biochemical mechanisms and apoptosis ("programmed cell death") is discussed. The study is a part in a larger survey aiming at an understanding of the formation of a mature stratum corneum with a functional barrier, and its changed properties in cases of skin disorder.

Apoptosis↗
PubMed1995

Human skin physiology studied by particle probe microanalysis.

Particle probe methods (electron probe and proton probe X-ray microanalysis) have been applied to investigate the distribution of elements and water over the different layers of the epidermis. For major elements, electron probe X-ray microanalysis (XRMA) provides the advantage of superior spatial resolution, but for trace element analysis the more sensitive proton probe (particle induced X-ray emission, PIXE) analysis has to be used. On a dry weight basis, the concentration of S is rather constant across the epidermis, whereas the concentrations of P, K, Cl and Na show gradients with high levels in stratum germinativum (basale) and stratum spinosum but low levels in the stratum granulosum and stratum corneum. Essentially, Fe and Zn are confined to the basal region in normal skin. The concentration of Ca, however, increased steadily from the basal region to the stratum corneum. The probe technique allows quantitative analysis of stratum-specific changes in elemental content in a variety of pathological conditions, e.g., changes induced by nickel, detergents and other chemicals, or in psoriatic skin. Of particular interest are findings of increased Fe and Zn in non-involved psoriatic skin. Since the different layers of the skin have different elemental concentrations and react differently under pathological conditions, the probe techniques are far superior to bulk chemical analysis in elucidating physiological and pathological processes in the skin.

Apoptosis↗
PubMed1991

Proton induced X-ray emission analysis of biological specimens--past and future.

Proton induced X-ray emission (PIXE) analysis is a comparatively new member of the family of spectrographic methods. In the last decade PIXE techniques have been applied to biological problems with great success. This review gives a condensed presentation of recent developments in biological (medical, zoological, and botanical) applications of PIXE analysis with special focus on factors which commonly influence the results, such as calibration, contamination, and preparation. The great advantage of PIXE analysis in studying physiologically important trace elements such as Zn, Mg, Fe, and Cu is underlined. Elemental mapping not only allows quantitative elemental analysis, but can also demonstrate the important differences in the morphological distributions of elements by comparing normal and pathological tissue.

Animals↗
PubMed1990

Accumulation of calcium in substantia nigra lesions induced by status epilepticus. A microprobe analysis.

Status epilepticus of sufficient duration (greater than 30 min) causes a unique lesion of substantia nigra pars reticulata (SNPR), and of globus pallidus (GP). This lesion, which encompasses a pan-necrotic destruction of neurons and glial cells seems to develop during ongoing seizures. We decided to investigate if the lesion is accompanied by net calcium accumulation. Seizures of 20 and 60 min duration were induced by the administration of flurothyl, and the tissue was frozen in situ either at the end of the seizure periods, or after recovery periods of 15 or 120 min. The total calcium and potassium contents of caudoputamen, neocortex, GP and SNPR were measured using particle induced X-ray emission (PIXE) in the microprobe mode. Seizures of 20 min duration did not cause net accumulation of calcium. When the duration of seizures was extended to 60 min the results varied depending on the location. In caudoputamen, which does not incur neuronal damage, no calcium accumulation was observed. In GP and SNPR, such a rise was unequivocally demonstrated, with calcium content increasing to about 150% of controls. The increase in calcium correlated to a decrease in potassium content. It is concluded that epileptic cell death occurs pari passu with accumulation of calcium although it cannot be stated that this accumulation is the cause of the cell death. It is speculated that seizures increase the permeability of the blood-brain barrier to calcium, and that enhanced blood to tissue transfer increases the calcium load of metabolically strained cells.

Animals↗
PubMed1988

Accumulation of calcium and loss of potassium in the hippocampus following transient cerebral ischemia: a proton microprobe study.

This study explored (a) whether postischemic accumulation of calcium in hippocampal neurons precedes or occurs pari passu with light microscopical signs of delayed neuronal necrosis, and (b) whether calcium initially accumulates in dendritic domains, presumed to have a high density of agonist-operated calcium channels. Transient ischemia of 10-min duration was induced in rats, and the animals were studied after 1, 2, 3, and 4 days of recovery. We measured total calcium and potassium contents in the stratum oriens, pyramidale, radiatum, and moleculare of the CA1 and CA3 sectors, using particle induced x-ray emission (PIXE) in the proton microprobe mode. The results showed significant accumulation of calcium and loss of potassium after 3 and 4 days of recovery in the CA1 sector, which developed neuronal necrosis, but not in the CA3 sector, which showed only occasional damage. In a few animals, calcium accumulation (and loss of potassium) was observed with no or only mild visible damage, but in the majority of animals the accumulation of calcium correlated to signs of neuronal necrosis. Since calcium accumulation was similar in all strata examined, the results failed to reveal preferential accumulation in dendritic or somal regions. Based on our results and those of Dux et al., we emphasize the possibility that delayed neuronal death is, at least in part, caused by increased calcium cycling of plasma membranes and gradual calcium overload of mitochondria.

Animals↗
PubMed1988

Proton microprobe and particle induced X-ray emission (PIXE) analysis for studies of pathological brain tissue.

Particle Induced X-ray Emission and proton microprobe analyses have been applied for the investigation of regional elemental distributions in connection with various pathological states in the brain. Malignant brain tumours and adjacent histologically intact tissue removed during surgery were analysed with PIXE. Systematic elemental variations, e.g., for calcium and selenium, were observed in the tumour front. The proton microprobe was applied to study the Ca and K concentrations in various cell strata in hippocampus following transient ischaemia in rat brain. Significant increases in the Ca level occurred in selectively vulnerable cells within 48 h after the ischaemia.

Animals↗
PubMed1987

Assessment of qualitative and quantitative data from pathological hairs--a critical evaluation of scanning electron microscope and proton induced X-ray emission analyses.

Analysis of single hair fibres in genetic disorders is a desirable complement to the clinical diagnosis. The scanning electron microscope (SEM) allows detailed study of the surface morphology of hair fibres which may explain some mechanical characteristics of the pathological hair. Quantitative elemental data may indicate biochemical or metabolic abnormalities. In this preliminary study we assess the feasibility of combining SEM and proton induced X-ray emission (PIXE) analysis on single hair fibres from 12 cases of genetic disease influencing the integument status. We conclude that SEM is a valuable tool in the analysis of hair pathology. The macro-PIXE technique involves some methodological and technical problems which in many cases are likely to be solved by using a proton microbeam. However, this means that routine methods have to be abandoned and careful selection of the material for analysis is an imperative necessity.

Adolescent↗
PubMed1986

Proton microprobe analysis in biology.

This paper is intended as an introduction to the field of proton microprobe analysis with special emphasis on applications in biological sciences. It is mainly intended for users of electron microscopes equipped with microprobes or other analytical equipment. The basic principles of Particle Induced X-ray Emission analysis are discussed as well as the instrumental requirements for the proton microprobe. The analytical characteristics including quantification procedures are compared with those of the electron microprobe and a review is given of various analytical applications of the proton microprobe within biology and medicine.

Animals↗
PubMed1986

Elemental content of anagen hairs in a normal Caucasian population studies with proton induced X-ray emission (PIXE).

The elemental content of anagen hair fibers in a Caucasian population of healthy females and males in the age range 10-69 years was performed to constitute a baseline for further studies of pathological conditions. Proton induced X-ray emission (PIXE) analyses were performed on single hair fibers in triplicate from 103 individuals in order to determine sulfur, zinc, calcium, and chlorine content. The hair fibers were all anagen hairs collected from a site little influenced by genetic and hormonal influences 1.5 cm above the right ear of the probands. An area 5-8 mm from the follicle bottom was chosen for the analysis in all cases to minimize effect of hair-do contamination. The average sulfur content was 0.049 g/g and the average zinc content 170 micrograms/g. These results were not significantly influenced by chloroform/ethanol rinsing before analysis. The calcium and chlorine contents were 330 micrograms/g and 0.0033 g/g respectively. The latter data are expected to be more seriously influenced by external factors (e.g., contamination) than sulfur and zinc. No correlation between elemental concentration and sex was found for sulfur and zinc in the present material. PIXE analysis of single hair fibers yields valuable information on the elemental composition of hair fibers and can be rapidly and efficiently performed after simple mounting procedures.

Adolescent↗
PubMed1985

Quantitative correlative proton and electron microprobe analysis of biological specimens.

To investigate the possibility of quantitative correlative proton microprobe (PMP) and electron microprobe (EMP) analysis of biological soft tissue, model specimens were analyzed by both techniques. The specimens consisted of freeze-dried sections of gelatin containing known concentrations of nickel chloride. Both for PMP and for EMP, the signal was expressed as the ratio of the characteristic intensity and the continuum intensity in a peak-free region of the spectrum. With both techniques, calibration curves (signal versus known concentration) obtained, showed a deviation from linearity at high nickel concentrations. However, a linear relation (correlation coefficient 0.996) was obtained in a plot of EMP signal versus PMP signal. This indicates that quantitative correlative PMP and EMP analysis can be carried out by using the same standard for both analytical techniques.

Animals↗
PubMed1984

Elemental analysis on freeze-dried sections of human skin: studies by electron microprobe and particle induced X-ray emission analysis.

The possibility of using the proton microprobe (PMP) in the elemental analysis of dermatological material, under conditions where the spatial resolution can be restricted to a few micrometers, was demonstrated. Comparison with the electron microprobe (EMP) technique using duplicate sections from the same human skin biopsies revealed that the PMP and EMP techniques are complementary and yield closely corresponding elemental distributions for elements of dermatological interest. The concentrations of phosphorus and potassium were low in the dermis, high in the stratum basale and stratum spinosum, and decreased markedly in the stratum granulosum to a low level in the stratum corneum. The sulfur concentration was highest in the stratum corneum.

Electron Probe Microanalysis↗
PubMed1983

Proton-induced X-ray emission analysis - a new tool in quantitative dermatology.

Proton-Induced X-ray Emission analysis (PIXE) constitutes a method for trace element analysis characterized by multielemental capability, detection limits in the low ppm-range and size resolution down towards a micrometre. In applications where the sensitivity of the Electron-Induced X-ray Emission (EIXE) analysis is not sufficient and where a spatial resolution not better than a few micrometres is required, the PIXE technique provides a powerful tool. In this paper properties of the PIXE method are demonstrated by quantitative results from three different samples of dermatological interest. Firstly, mercury results from a longitudinal scan of a single hair strand from a mercury poisoned person are shown. With a spatial resolution of one or a few millimetres very fast scans may be performed on hair strands giving information on time and magnitude of intoxication or other exposures, as well as deficiencies. Secondly, results are given from a radial scan with a beam width of 4 micron on hair from a person exposed to high amounts of iron. The calcium, iron and zinc distributions but not the sulphur and potassium distributions show narrow peaks of concentration (less than 4 micron) about 15 micron from the surface of the hair. Further investigations have to be performed in order to interpret these data. Thirdly, the depth profiles in skin of some elements were measured with a beam width of 10 micron. The results show significant increases in sulphur, calcium and zinc concentrations and significant decreases in phosphorous and potassium concentrations at the skin surface, i.e. in the stratum corneum.

Adult↗
PubMed1982

Lead levels determined in Swedish permanent teeth by particle-induced X-ray emission.

The determination of lead in permanent teeth is a useful measure of past exposure in early childhood since these teeth are mineralized in early childhood. Particle-induced X-ray emission (PIXE) analysis has been shown to be a method with good applicability for the contamination-free analysis of elements heavier than calcium in dental hard tissues. The method is rapid and nondestructive. The purpose of this study, which used the PIXE technique, was to survey the average level of lead in the coronal dentin of permanent bicuspid teeth collected in three places representing Swedish urban and rural areas. In addition teeth from the New York City area were analyzed. The material comprised 165 teeth from Sweden and, for comparison, 14 teeth from New York City. The median value of lead in the Swedish teeth was 2.9 micrograms/g, a value indicating an insignificant influence from the environment in comparison to the New York teeth, for which the median value was 9.2 micrograms/g. There was however a statistically significant difference in the lead concentration of teeth from large and small Swedish cities; this finding may reflect different automobile traffic intensity.

Adolescent↗