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Zink (Zn) är ett mikronäringsämne som är nödvändigt för människans fysiologi. Upptaget av zink varierar beroende på kostens innehåll av zink samt om den innehåller ämnen som är hämmande eller stimulerande på zinkupptaget. Syftet med studien var att undersöka vilket referensområde som är normalt för zink i plasma och serum hos friska personer samt att undersöka risken för kontamination av zink från rör, korkar och pipettspetsar. Syftet var även att jämföra zinknivåerna i plasma och serum efter ett intag av zink i 4 veckor, samt att jämföra zinknivåerna med body mass index (BMI), albumin, östradiol samt markörer för inflammation och järnstatus. Sammanlagt 54 subjektivt friska personer rekryterades till studien, främst studenter från Linköpings universitet och personal inom laboratoriemedicin, Region Östergötland. Venprovtagning utfördes på forskningspersonerna och zinkproverna analyserades på Konelab 30i med en spektrofotometrisk metod. Resultatet visade att zinknivåerna i serum och plasma hos friska personer är lägre än de referensintervall som är angivna inom laboratoriemedicin samt i litteraturen. Det visade även att kontaminationsrisken av zink från rör, pipettspetsar och korkar är ytterst liten. Efter tillskott av zink ökade zinkkoncentrationen i serum och plasma (p<0,001). När det gällde övriga parametrar var det endast ferritin hos gruppen med låga utgångsvärden som visade signifikant lägre värden efter zinktillskott. Slutsatsen blir att referensområdet för zink hos friska personer bör justeras. Risken för kontamination av zink från rör, pipettspetsar och korkar är mycket liten och att dessa material som används idag kan fortsätta användas i samband med zinkanalyser. / Zinc is a micronutrient that is essential for human health and development. The uptake of zinc from the diet is dependent on the relative zinc content in the diet, and the presence of elements that act as inhibitors or facilitators for the uptake of zinc. The purpose of the present study was to investigate zinc in plasma and serum samples from healthy individuals in relation to the current reference interval for zinc. A contamination test was also performed to investigate the risk of zinc contamination from tubes, corks and pipettes. An additional purpose was to compare the circulating levels of zinc after zinc supplementation for 4 weeks, and to compare the levels of zinc to body mass index, albumin, estradiol and markers for inflammation and blood iron status. Participating subjects were mainly students from Linköping University and employees from the Department of Clinical Chemistry, Region Östergötland. Venous sampling was carried out and samples were analyzed on a Konelab 30i with a spectrophotometric method for determination of plasma and serum zinc. The results showed that the levels of zinc in serum and plasma from healthy individuals were lower in comparison with the current reference interval and also in comparison with the current literature. It was also shown that the risk of contamination of zinc from tubes, pipettes and corks is insignificant. After zinc supplementation, the zinc levels increased in serum and plasma (p<0,001). For the remaining parameters, the only significant change after zinc supplementation was a lower level of ferritin in the subjects with low starting levels. In conclusion, we suggest that the current reference interval for serum zinc should be adjusted. The risk of contamination of zinc from tubes, pipettes and corks is insignificant and that the sampling materials in use today can be used onwards for determination of serum zinc.

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Studies in animals and humans link both physical and psychological stress with an increased rate and severity of infections and onset of diseases. Stress is a very broad and complex topic. It can be defined as a condition occurring in response to adverse external influences capable of affecting physical health which leads to activation of a stress response in the body. There are two prominent stress responsive systems: the hypothalamic-pituitary-adrenal axis and the sympathetic adrenomedullary axis. These systems are responsible for the majority of the changes in the body, which occur in response to stress. Stress has been linked to many detrimental effects in cattle including immune suppression, increased disease susceptibility and decreased reproduction. These cause huge economic losses to the cattle industry every year. Weaning has been identified as one of the main stressors implicated in these negative effects. For this reason it is important to be able to identify animals stressed by weaning and do so using samples which are easily obtainable and useful for future diagnostic purposes. We hypothesize that weaning will cause sufficient stress in cattle to alter protein profiles in serum, which can be used to identify this type of stress. To do this we employed proteomic methodologies including two-dimensional gel electrophoresis and mass spectrometry to compare an abrupt weaned group of calves to a never weaned group and a previously weaned group (preconditioned). We have included a preconditioned group to examine the differences between this group and animals which have never been weaned. Preconditioned animals are typically used as a control group in weaning studies. A total of 83 distinct protein bands were identified after image analysis. Out of 83 protein bands, we found 9 spots which were significantly different in abundance among the treatment groups. Two out of 9 spots were significantly different between the abrupt weaned and the never weaned groups. Five protein bands were also found to be significantly different between the abrupt weaned group and the preconditioned group. Five protein bands were found to be significantly different between the never weaned group and the preconditioned group. Identification of these proteins, however, had limited success since the bovine protein database is not as extensive as that for humans or mice. Among the proteins identified were alpha-1-acid glycoprotein and collagen precursor. The differences in intensities found between the abrupt weaned group and the never weaned group may be useful as markers of calves going through weaning stress. We have also seen that animals who have undergone weaning and through the stress associated with that event are not exactly the same as animals which have never been weaned. This has implications to research where a preconditioned group is used as a control rather than a never weaned group. Despite the limitations of the methodology used for the current system, the overall results revealed specific changes in serum proteins which were associated with abrupt weaned animals. Future studies can be planned to determine the specificity of these protein changes and possibly identify the molecular basis of stress dependent disease susceptibility.

Studies in animals and humans link both physical and psychological stress with an increased rate and severity of infections and onset of diseases. Stress is a very broad and complex topic. It can be defined as a condition occurring in response to adverse external influences capable of affecting physical health which leads to activation of a stress response in the body. There are two prominent stress responsive systems: the hypothalamic-pituitary-adrenal axis and the sympathetic adrenomedullary axis. These systems are responsible for the majority of the changes in the body, which occur in response to stress. Stress has been linked to many detrimental effects in cattle including immune suppression, increased disease susceptibility and decreased reproduction. These cause huge economic losses to the cattle industry every year. Weaning has been identified as one of the main stressors implicated in these negative effects. For this reason it is important to be able to identify animals stressed by weaning and do so using samples which are easily obtainable and useful for future diagnostic purposes. We hypothesize that weaning will cause sufficient stress in cattle to alter protein profiles in serum, which can be used to identify this type of stress. To do this we employed proteomic methodologies including two-dimensional gel electrophoresis and mass spectrometry to compare an abrupt weaned group of calves to a never weaned group and a previously weaned group (preconditioned). We have included a preconditioned group to examine the differences between this group and animals which have never been weaned. Preconditioned animals are typically used as a control group in weaning studies. A total of 83 distinct protein bands were identified after image analysis. Out of 83 protein bands, we found 9 spots which were significantly different in abundance among the treatment groups. Two out of 9 spots were significantly different between the abrupt weaned and the never weaned groups. Five protein bands were also found to be significantly different between the abrupt weaned group and the preconditioned group. Five protein bands were found to be significantly different between the never weaned group and the preconditioned group. Identification of these proteins, however, had limited success since the bovine protein database is not as extensive as that for humans or mice. Among the proteins identified were alpha-1-acid glycoprotein and collagen precursor. The differences in intensities found between the abrupt weaned group and the never weaned group may be useful as markers of calves going through weaning stress. We have also seen that animals who have undergone weaning and through the stress associated with that event are not exactly the same as animals which have never been weaned. This has implications to research where a preconditioned group is used as a control rather than a never weaned group. Despite the limitations of the methodology used for the current system, the overall results revealed specific changes in serum proteins which were associated with abrupt weaned animals. Future studies can be planned to determine the specificity of these protein changes and possibly identify the molecular basis of stress dependent disease susceptibility.

Iron is important for human health and serves as a co-factor in a variety of proteins and enzymes. Human serum transferrin (hTF) is an Fe(III) transporter in blood plasma which delivers metal to cells via a receptor-mediated endocytosis. In the first part, crystal structures of FeNFeC-hTF and BiNFeC-hTF have been characterized. The N-lobes of the two structures adopt “partially opened” conformations between holo-hTF’s “closed” and apo-hTF’s “fully-opened” states. The N-lobe of BiNFeC-hTF opens wider than FeNFeC-hTF. Their metal-bound C-lobes are totally closed. Rigid-body movement and different inter-lobal hydrogen bonds for the “partially opened” conformations are observed. The binding affinities of four putative binding residues are in the order: Tyr188>Tyr95>Asp63~His249. In the N-lobe of BiNFeC-hTF, Tyr188, bicarbonate and a nitrilotriacetate (NTA) ion bind to Bi(III), whilst Tyr95 and Asp63 interact with NTA ligand. One (BiNFeC-hTF) or two (FeNFeC-hTF) glycan molecules are identified on the surface area of C-lobe. In the second part, biocoordination chemistry of selected metal ions was investigated using hTF as a template. The Al(III), Fe(III), Ga(III), Dy(III) and Yb(III)-bound hTF exhibit closed conformations in the C-lobe and “fully-opened” conformations in the N-lobe. In these structures, malonate serves as an anion in the C-lobe and provides two tunable ligation sites that lead to a less distorted octahedral coordination geometry. As a result, the large lanthanide ions (Dy(III) and Yb(III)) turn from their favored high coordination numbers (8~12) and fit into the protein’s hexadental pocket. Unexpectedly, in the presence of malonate ion and the excess amount of Dy(III) ion, the Ga(III) can be partially replaced by Dy(III), although Ga(III) has a much higher affinity than Dy(III) towards the protein. The chaperone system in Helicobacter pylorithat helps protein refold is assembled with HspB and HspA. In the third part, preliminary crystallographic work is reported for HspB and HspA. The chaperone HspB has been crystallized under various conditions and currently the diffraction resolution is 6.8Å. The co-chaperone HspA, which binds Bi(III) tightly, although its crystals diffract to 1.6Å, still needs improvement for data collection due to radiation damage.The crystal structure of HspB revealed that HspB presents as a single-ring heptamer, though it is a mixture of dimer, tetramer and a higher oligomer in solution. The interactions between HspB monomers in crystal structure are significantly weaker than that of GroEL (counterpart in Escherichia coli) monomers which may makes the HspB heptamer easier to dissociate in solution. / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

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Thesis (M. Phil.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 94-104). Also available in print.