| 31. |
- Sigurs, Nele
(author)
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Studies on sensitization and atopic disease in infants and children
- 1995
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Doctoral thesis (other academic/artistic)abstract
- Sensitization to food allergens dominated in infancy and IgE antibodies to inhalant allergens appeared later in a cross-sectional multicentre study of 224 children with atopic disease (113 children aged 0-3 years and 111 children aged 4-15 years). IgE antibodies to peanut, hazelnut, and almond were important in both age groups and even before known ingestion in infancy, suggesting sensitization through breast-milk.A similar pattern of food sensitization in infancy and later appearance ofantibodies to inhalant allergens was seen in 324 children constituting an enlarged group from three different cohorts of children and followed prospectively from birth to age 4 to 15. Antibodies to inhalant allergens developed in 76% of children with IgE antibodies to egg white (EW) in infancy. Of children with inhalant antibodies up to age 12-15, 32 % had previously had antibodies to EW.The possible effects of maternal antigen avoidance during lactation on the development of atopic disease were studied in children with a positive family history of atopy. The mothers of 65 infants avoided eggs, cow's milk and fish during the first three months of lactation, whereas the mothers of 50 infants had no dietary restrictions. (Previous reports from this study had shown significantly less atopic dermatitis (AD) during the first 6 months of life in the diet group, and after that a non-significant trend towards less AJ;:> up to age 18 months.) The present follow-up at age 4 years showed significantly less AD in the diet group, both as cumulative (29 %versus 56 %, p=0.007) and as current prevalence (12 % versus 38 %, p=0.03). The frequencies of asthma and allergic rhinoconjunctivitis were similar, as were the number of sensitized children.Possible effects of an early severe respiratory viral infection on the development of asthma, other atopic symptoms and sensitization were studied in 47 infants hospitalized with respiratory syncytial virus (RSV) bronchiolitis, and their 93 matched controls obtained from the local child health centres. Asthma, up to age 3, was significantly more common in the RSV children (23% versus 1 %, p< 0.001). This was also the case with serisitization at age 3, as measured by skin-prick tests and two screening tests in serum for food and inhalant antibodies (32 % versus 9 %, p=0.002), whereas the frequency of AD was similar in the two groups. The combination of RSV bronchiolitis and a family history of asthma was the most important risk factor for the development of asthma. For sensitization, the combination of RSV bronchiolitis and a family history of atopic disease was the most important risk factor.In a study of 34 infants hospitalized with RSV bronchiolitis, the eosinophil cationic protein (ECP)/albumin ratios in nasal secretions increased during the 6 months following RSV bronchiolitis, suggesting a long-standing inflammatory reaction, which might be important for the high frequency of post-bronchiolitic wheezing. ECP and myeloperoxidase in serum and ECP/albumin ratios in nasal secretions could not be used to predict later asthma or sensitizat:ion.In conclusion, food sensitization dominated in infancy, and antibodies toaeroallergens appeared later. In infants with a family history of atopic disease, the risk of developing atopic dermatitis up to age 4 years was reduced in the group in which the mothers avoided cow's milk, egg and fish during lactation. An early RSV bronchiolitis increased the likelihood of future asthma and sensitization up to age 3 especially if combined with heredity for asthma and atopic disease.
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| 32. |
- Sparring Björkstén, Karin
(author)
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Neurobiological aspects on brain function in neuro-psychiatric patients and in healthy subjects
- 1995
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Doctoral thesis (other academic/artistic)abstract
- The levels of insulin-like growth factor-2 (IGF-2) were assessed in lumbar cerebrospinal fluid (CSF) from children with various kinds of brain damage and from Alzheimer (AD) patients and controls. Whole CSF was separated using acid gel chromatography and the presence of insulin-like growth factor binding protein and two different kinds of free IGF-2 m the CSF was established. The levels of CSF-IGF-2 were higher in the new-born infants than in children aged 6 months - 4 years. This difference was ascribed the immature blood-brain barrier in infants. Older children had levels similar to those reported in adults. Children with hydrocephalus had very low levels of IGF-2. The levels ofiGF in unseparated CSF was similar in AD patients and controls.The relationship between CSF spaces and cognitive function was investigated in patients with AD and controls, using a low field magnetic resonance imaging (MRI) technique and psychometric tests. The AD patients had larger relative CSF volumes in all locations investigated. The greatest differences between the two groups were found in the volumes of the temporal horns. The CSF volumes in the basal parts of the brain correlated inversely with episodic memory tests. The relative volumes of the lateral ventricles correlated with the degree of dementia. It was concluded that measurements of the relative CSF volumes of the temporal horns by MRI might be a reliable diagnostic sign of AD as well as providing an estimation of the severity of the disease.Demented subjects with either a severely disorganised sleep-wake schedule or regular sleep habits underwent serial blood saropling. The subjects with disorganised sleep-wake schedules had disturbed circadian rhythms of plasma melatonin (MT) and cortisol, whereas those with regular sleep habits had normal plasma MT and cortisol profiles. An 82-year old lady with vascular dementia and a disturbed sleep-wake pattern improved her sleep and normalised plasma MT and cortisol patterns after the removal of a beta-adrenergic blocker, substitution of cobalamin deficiency and cataract surgery. A man with frontal lobe dementia who was assessed repeatedly showed inability to suppress MT as assessed by a light test. A disorganised sleep-wake cycle in demented patients may in some cases be reflected by irregularities in the secretion of MT and cortisol.Eleven healthy elderly with normal levels of plasma cobalamin were hospitalised for a serial blood sampling procedure drawing blood every two hours over a 24 hourperiod. It was concluded that there was no circadian variation of plasma cobalamin, unsaturated binding capacity of transcobalamin and haptocorrin, or transcobalamin bound cobalamin other than what can be explained by posture. The proposed role for cobalamin in the regulation of the circadian rhythm could not be confirmed by this study.Different methods of assessing the circadian rhytm were reviewed. Awristworn, computerised instrument recording activity and light expsoure was introduced. The light exposure in 14 healthy elderly in Linköping, Sweden, under normal living conditions was analysed using the new instrument. The subjects were exposed to very little light, mostly indoor illumination. The median subject spent 60 % of the time in illumination <:1 Lux, 10 % in <: 100 Lux, and 2 % in <:1000 Lux. Only four subjects were exposed to <: 1000 Lux for 60 minutes or more, which is regarded as a minimum requirement for maximal MT suppression.In addition, simultaneous light recording and blood saropling was done over a 24 hour period. All subjects showed low day-time levels and distinct nocturnal rises of MT. Cosinor analysis was applied on the MT and light data. The time interval from the acrophase of light to the acrophase of MT was delayed with the progress of the autunm and diminishing light.
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| 33. |
- Tuisku, Fredrik
(author)
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Nerve fibres in relation to gingiva, tooth germs and teeth in the polyphyodont cichlid Tilapia mariae
- 1995
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Doctoral thesis (other academic/artistic)abstract
- In the late 19th century Retzius observed the presence of nerve fibres in goldfish tooth pulps. However, later studies on the relationship between the dentition and its innervation in non-mammalian vertebrates and its use in experimental research are rare. This thesis presents data on how nerve fibres are related to gingiva, tooth germsand teeth in the lower jaw of a polyphyodont teleost- the cichlid Tilapia mariae. It provides some new aspects on the structure and function of gingival and dental axons. Paper I shows that the complexity of the nodal-paranodal organization in trigeminal alveolar branch (TAB) nerve fibres decreases with decreasing fibre size, like in mammalian nerve fibres. The exceptionally thin myelinated TAB fibres of T. mariae (axonal diameters down to 0. 3 µm) exhibit nodes of Ranvier. The internodal lengths of these fibres varies between 35-50 µm. Theoretical calculations suggest that these extremely thin fibres may be capable of saltatory conduction. Paper II shows that the normal turnover time of an individual tooth (i.e. from eruption to shedding)is about 100 days. Following unilateral neurectomy of the TAB, tooth turnover stops on the denervated side of the jaw. The arrest in tooth turnover is due to a cessation of tooth germ formation. Papers III and IV show that gingival and dental domains are extensively innervated by nerve fibres exhibiting neurofllarnent-, calcitonin generelatedpeptide-, substance P-, tyrosine hydroxylase-, neuropeptide Y -,choline acteyl transferase- or vasoactive intestinal polypeptide-like itnmunoreactivity in a pattern similar to the mammalian counterpart. The rich innervation of odontogenic tissue components in T. mariae by sensory as well as autonomic axons is compatible with the results obtttined in paper II that axons may be involved in odontogenesis. Paper V shows that gingiva and tooth pulps in T. mariae are innervated by trigeminal ganglion (TG) neurons. Like in the rat, TG neurons in T. mariae differ in size and neuropeptide content depending on whether they project to gingiva or tooth pulps.While gingival neurons are exclusively small (perikaryal diameter [Pd]< 20 µm), pulpal neurons may be small or large (Pd;o: 20 µm). Hence, this seems to be an evolutionary old pattern. Taken together, the present results show that the lower jaw dentition and its trigeminal branch in T. mariae is a useful experimental system that may be used for future studies on e. g. the functional properties of the exceptionally thin TAB fibres or the molecular mechanisms behind the neuronal influence on tooth germ formation.
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| 34. |
- Wirén, Michael
(author)
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Growth and integrity of the small intestine in malnutrition and trauma
- 1995
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Doctoral thesis (other academic/artistic)abstract
- The small intestine is an active metabolic organ constituting a functional and immunologic barrier to toxins and microbes in the intestinal lumen. Injuries are repaired by rapid cell replication, which depends on nutritional and humoral growth factors. Glutamine has been suggested to be the most important nutrient for the enterocytes. In the present studies, the effects of glutamine were evaluated using experiments with cultured cells and postoperative supplementation in animals and humans.Growth of two enterocyte-like epithelial cell lines, CaCo-2 and HT 29, was studied at different glutamine concentrations, and compared to effects of growth factors and energy substrates. Glutamine effects in starved, operated rats were evaluated by weight, DNA, protein analysis, 3H-thymidine incorporation in intestinal mucosa and urinary recovery of orally administered polyethylene glycols. Three different balanced and complete enteral preparations with no glutamine, 2% (normal) and 4% were used postoperatively . Growth parameters and tissue and plasma concentrations of humoral growth factors were studied 3 and 8 days after intestinal resection in the rat. In a clinical study with total parenteral nutrition for five days after major abdominal surgery, nitrogen balance and humoral growth factors in plasma were evaluated in patients receiving glutamine-containing dipeptide (Gly-Gln) amino acid solution, compared to conventional amino acid solution.In the cell cultures, glutamine was shown to be of importance both as a trophic factor and as a metabolic substrate, particularly in cells of intestinal origin. In the animal model of malnutrition and surgery, 3H-thymidine incorporation was higher in the supplemented group compared to glutamine-free and also higher in all operated groups compared to controls. The permeability study showed a higher uptake of small polyethylene glycol molecules in glutamine-supplemented animals, parallel to increases in thymidine incorporation. After major intestinal resection in rats, no major benefit on growth by glutamine supplementation could be found after one week. Rapid PYY increases in plasma and higher IGF-II concentration in ileal mucosa were found. Stimulation of IGF-II concentration suggested an auto- or paracrine action in regulating growth. In the clinical study, no significant differences were seen in the levels of transthyretin, retinol binding protein or nitrogen balance, compared to patients recieving conventional amino acid solution. A positive correlation between insulin and nitrogen balance was found inglutamine treated patients.It is concluded that glutamine has important effects as a nutritional substrate for enterocytes and stimulates their proliferation and absorptive capacity in refeeding after malnutrition and surgical trauma in the rat. After intestinal resection, glutamme has no major effects upon growth one week after surgery, but the production of growth factorsincreases earlier in glutamine supplemented animals. In clinical use, a glutamine supplemented amino acid solution appeared no better than conventional amino acd solution. It could, howeyer, represent a more balanced way of supportmg protem metabolism after trauma, by the interaction with insulin and other growth factors.
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| 35. |
- Yin, Dazhong
(author)
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Age pigments and the biochemical basis of their formation
- 1995
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Doctoral thesis (other academic/artistic)abstract
- The autofluorescent, yellow-brown pigments that accumulate over time inbiological organisms are called age pigments. Lipofuscin, known as a hallmark of aging, refers to intracellular age pigments that accumulate mainly in the lysosomes of postrnitotic cells. This dissertation reports studies on the biochemical nature of lipofuscin and other age pigments, including their origin, mechanisms of formation, composition, structure and other properties.Since lipofuscin-extracts and lipid peroxidation products exhibit similar fluorescent characteristics, oxidative stress-induced lipid peroxidation is linked with age pigment formation. The initiation of lipid peroxidation resulting from oxygen free radicals was studied in a Tween 20-emulsified linoleic acid model system. Fenton reagents did not result in hydrogen abstraction-related diene conjugation. Also, different cOmbinations of Fe(II) and Fe(III) did not support the Fe(II):Fe(Ill) (1: 1) optimum ratio hypothesis. It is, therefore, concluded that perferryl ions or chelator-Fe-02 complexes are responsible for the first-chain initiation of lipid peroxidation in this model system.To elucidate a mitochondrion-lysosome hypothesis of lipofuscinogenesis, the oxidative stress-induced formation of lipofuscin-like fluorophores was studied in a testtube model using lysosomal-mitochondrial fractions. The sequential formation of TEARS, protein carbonyls and lipofuscin-like fluorophores was found. These findings add support to the concept that lipofuscin fonns in secondary lysosomes as a result of iron-catalyzed oxidative reactions involving autophagocytosed materials.Further, lipofuscin-like fluorescence was obtained during ascorbic acidautoxidation and from reaction products between ascorbic acid and amino compounds. The reaction between ascorbic acid and glutamine shows that such fluorophore formation is oxidation-dependent. On the basis of a comparison of the fluorophore formation mechanisms of lipid peroxidation, ascorbate oxidation and glycation reactions, we propose that carbonyl-protein crosslinking is a common biochemical reaction in aging processes.Striking discrepancy exists between the orange-yellow fluorescence of lipofuscin in situ and the blue fluorescence of lipofuscin-extracts. A concentration-dependent fluorescence shift was discovered using different lipofuscin-related fluorophores. The methodological difference between microfluorometry, by which lipofuscin is studied in highly condensed form, and spectrofluorometry, by which lipofuscin is studied at a very low concentration, is also clarified.These studies suggest that crosslinking between carbonyls and amino compounds may represent the major biochemical process responsible for the formation of age pigments and lipofuscin-like fluorophores.
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| 36. |
- Zhang, Hong, 1957-
(author)
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Alloxan Toxicity to macrophages and Insulinoma Cells
- 1995
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Doctoral thesis (other academic/artistic)abstract
- Alloxan induces damage and death of pancreatic islet B-cells in severalexperimental animal models, thus causing insulin-dependent diabetes mellitus (IDDM or type I diabetes). This unique cytotoxicity of alloxan has been studied for more than fifty years. The mechanisms behind the cytotoxicity of alloxan have, however, never been fully understood, although an increasing number of authors now suggest formation of reactive oxygen species, targeting the plasma membrane, mitochondria and DNA. In the present study, we have investigated: (i) the production of superoxide and hydrogen peroxide during reactions between alloxan and reducing agents such as cysteine, reduced glutathione, and ascorbic acid; (ii) the cytotoxic effects of alloxan in the absence of reducing agents, on model systems of cultured macrophages and insulinoma cells; (iii) the cytotoxicity of alloxan together with the reducing agents on these cultured cells; (iv) the cytotoxicity of hydrogen peroxide, used at concentrations similar to those formed during the reactions of alloxan with reducing agents; (v) the influence of iron and the iron-chelator, desferrioxamine, on the alloxan-induced cytotoxicity; and (vi) the influence of starvation-induced autophagocytosis on the sensitivity of cells to hydrogen peroxide-induced oxidative stress. Cell viability was estimated by a delayed trypan blue dye exclusion test and plasma membrane permeability by a modified microfluorometric combined fluorescein diacetate-propidium iodide staining technique. Lysosomal membrane stability was microfluorometrically assayed by acridine orange and neutral red relocalization techniques. The intracellular amounts of iron, reduced glutathione, antioxidant enzymes, and ATP were biochemically and cytochemically studied under a variety of conditions. The results showed that: (i) superoxide artion radicals and hydrogen peroxide were produced by reactions between alloxan and several reducing agents (e.g. cysteine, reduced glutathione and ascorbic acid). Hydrogen peroxide readily diffused through cellular membranes into the lysosomes if it was not previously degraded by the cellular antioxidative defence systems. Hydroxyl radicals might be produced by intralysosornal Fenton reactions, if reactive iron was present, resulting in lysosomal membrane damage followed by a leakage of lysosomal lytic enzymes with ensuing cell degeneration and eventually cell death. (ii) If iron was adsorbed to plasma membranes, extracellularly produced superoxide anion radicals and hydrogen peroxide might cause the plasma membrane damage due to Fenton reactions. (iii) Preincubation with desferrioxamine, or the presence of catalase inhibited the cytotoxicity induced by alloxan and reducing agents. (iv) The antioxidative defence activity of insulinoma cells was low. (v) Starvation in PBS enhanced the sensitivity of both macrophages and insulinoma cells to oxidative stress induced by hydrogen peroxide mediated through increased activity of autophagocytotosis. Thus, the amount of intralysosomal reactive iron consequently resulted from the degradation of various iron-containing metallo-proteins. We conclude that the exposure of cells to alloxan together with a reducing agent created cellular oxidative stress through extracellular formation of superoxide anion radicals and hydrogen peroxide. The latter compound easily penetrated plasma and lysosomal membranes, reaching the lysosomal interior. If enough reactive iron was present within lysosomes and the hydrogen peroxide was not degraded by catalase or glutathione peroxidase before entering the acidic vacuolar apparatus hydroxyl radicals could be produced via intralysosomal Fenton reactions.The hydroxyl radicals, in turn, would attack and damage the lysosomalmembranes, causing a leakage of lysosomal enzymes to the cytosol and eventually leading to cell death. The sensitivity of cells to alloxan-induced cytotoxicity in the presence of reducing agents was therefore a function of (i) the rate of hydrogen peroxide production, (ii) the cellular antioxidative defence systems, (iii) the lysosomal amount of reactive iron, and (iv) the capacity of autophagocytosis.
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