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Biomedical subjects

L Petersson

Publications and source records attributed to L Petersson.

At least 19 recordsLinked to original sources
PubMed2004

Prediction of vitamin A, vitamin E, selenium and zinc status of periparturient dairy cows using blood sampling during the mid dry period.

Vitamins A and E, and the trace elements selenium (Se) and zinc (Zn) are essential for the health and performance of dairy cows. Their concentrations often decrease around calving and extra supplementation is sometimes recommended at that time. However, the need for this varies, for example depending on quantity and quality of feedstuffs in the diet. The aim of this study was to measure the concentrations of serum vitamin A (S-vit A) and vitamin E (S-vit E), plasma Se (P-Se) and serum Zn (S-Zn) in blood samples taken at several time points from one month before to one month after calving, and to evaluate if a blood sample taken during the mid dry period can accurately predict the blood concentration at calving and early lactation. Dairy cows on 3 different feeding regimens during the dry period were included in the study. A significant decrease in the concentrations of S-vit A and S-vit E, and S-Zn, was observed at calving, and P-Se was significantly lower during the dry period and at calving than in early lactation. The blood concentrations of S-vit E and P-Se in the mid dry period significantly predicted the occurrence of values considered marginal or deficient at the time of calving. The data indicate that a mid dry period concentration of > or = 5.4 mg/l of S-vit E and > or = 0.09 mg/l of P-Se will result in a 90% chance that the cow stays above marginal levels at calving given that a feed of the same quality is offered.

Animals↗
PubMed2001

Changes in some blood micronutrients, leukocytes and neutrophil expression of adhesion molecules in periparturient dairy cows.

Dairy cows are highly susceptible to infectious diseases, like mastitis, during the period around calving. Although factors contributing to increased susceptibility to infection have not been fully elucidated, impaired neutrophil recruitment to the site of infection and changes in the concentrations of some micronutrients related with the function of the immune defence has been implicated. Most of the current information is based on studies outside the Nordic countries where the conditions for dairy cows are different. Therefore, the aim of the study was to evaluate changes in blood concentrations of the vitamins A and E, the minerals calcium (Ca), phosphorous (P), and magnesium (Mg), the electrolytes potassium (K) and sodium (Na) and the trace elements selenium (Se), copper (Cu) and zinc (Zn), as well as changes in total and differential white blood cell counts (WBC) and expression of the adhesion molecules CD62L and CD18 on blood neutrophils in Swedish dairy cows during the period around calving. Blood samples were taken from 10 cows one month before expected calving, at calving and one month after calving. The results were mainly in line with reports from other countries. The concentrations of vitamins A and E, and of Zn, Ca and P decreased significantly at calving, while Se, Cu, and Na increased. Leukocytosis was detected at calving, mainly explained by neutrophilia, but also by monocytosis. The numbers of lymphocytes tended to decrease at the same time. The mean fluorescent intensity (MFI) of CD62L and CD18 molecules on blood neutrophils remained constant over time. The proportion of CD62L+ neutrophils decreased significantly at calving. The animals were fed according to, or above, their requirements. Therefore, changes in blood levels of vitamins, minerals and trace elements were mainly in response to colostrum formation, changes in dry matter intake, and ruminal metabolism around calving. Decreased levels of vitamins A and E, and of Zn at calving might have negative implications for the functions of the immune defence. The lower proportion of CD62L+ neutrophils at calving may result in less migration of blood neutrophils into the tissues, and might contribute to the increased susceptibility to infections at this time.

Animal Nutritional Physiological Phenomena↗
PubMed2000

Effectiveness of two fluoride dentifrices to arrest root carious lesions.

PURPOSE: To compare the effectiveness of Prevident 5000 Plus (5,000 ppm F) and Colgate Winterfresh Gel (1100 ppm F) to arrest root carious lesions. MATERIALS AND METHODS: 201 subjects with at least one root carious lesion were recruited from dental school patients. They were randomly assigned to use either Prevident 5000 Plus (5000 ppm F) or Colgate Winterfresh Gel (1100 ppm F) as sodium fluoride in the same silica base. Measurements of lesion hardness, area, distance from the gingival margin, cavitation and plaque were recorded at baseline and after 3 months by a single examiner. RESULTS: After 3 months 38% of subjects using Prevident 5000 Plus and 10% using Winterfresh Gel had one or more lesions that had become hard (P < 0.001). Non-cavitated lesions at baseline were more likely to become hard than cavitated lesions. Compared to the Winterfresh group there was significant increase in the distance from the base of the lesion to the gingival margin and plaque scores were reduced in those using Prevident 5000 Plus.

Adult↗
PubMed1999

Lead poisoning in woodpeckers in Sweden.

Lead poisoning was demonstrated in two gray-headed woodpeckers (Picus canus) and one white-backed woodpecker (Dendrocopus leucotos) in Sweden; they had liver lead levels between 9.4 and 26.2 mg(-1) wet weight. At necropsy one gray-headed woodpecker showed signs of emaciation and the other one had severe traumatic injuries, caused by a cat. The white-backed woodpecker died in the transportation box during a translocation program. The source of the lead could not be determined, but it was suspected that it may have originated from lead pellets shot into trees and picked out by the woodpeckers during food search.

Animals↗
PubMed1998

Reduced cadmium levels in human kidney cortex in sweden.

Environmental pollution with the nephrotoxic metal cadmium is considered a potential health risk for the general population. In 1976 it was reported that the cadmium concentration in human kidney cortex in Sweden had increased in parallel with increasing levels in soil and grain during the twentieth century. Since the cadmium concentration in farming lands is still increasing, the present study was undertaken to further elucidate whether the cadmium concentration in the kidney is still increasing. Kidney cortex biopsies were collected at 171 autopsies of victims to sudden and accidental death during 1995 and 1996, and the cadmium concentrations were determined and compared with previously published Swedish data obtained from forensic autopsies. The geometric mean cadmium concentration in kidney cortex in subjects 40 years of age and younger was about 40% of the concentration found in the 1970s, while the reduction was less pronounced among older people. The highest individual concentration of cadmium was 41.5 microg/g wet weight (ww). The geometric mean concentration was less than 14 microg/g ww at ages around 50 years of age, when the cadmium concentration in kidney cortex is highest, as compared with approximately 20 microg/g ww in the 1970s. There was also a reduction in cadmium concentrations among nonsmokers; thus, a decrease in tobacco smoking in Sweden during the last decades is not the only explanation for the reduction of cadmium in the kidney cortex. Other reasons for this reduction could be changes in dietary habits and reduced cadmium contamination from Swedish industries.

Adult↗
PubMed1995

Delmopinol interactions with cell walls of gram-negative and gram-positive oral bacteria.

The main purpose of the present study was to investigate the influence of delmopinol hydrochloride on the cell surface morphology of gram-negative and gram-positive bacterial cells by using transmission electron microscopy. A second purpose was to evaluate the extraction of cell wall material caused by delmopinol and the binding of radiolabelled delmopinol to the various strains. Fresh isolates and type strains of gram-negative rods associated with periodontal disease, Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, and strains of the gram-positive streptococci Streptococcus sanguis, Streptococcus mutans and Streptococcus salivarius, were exposed to 3.2 mM (0.1%) or 6.4 mM (0.2%) delmopinol hydrochloride from 1 to 90 min. For electron microscopy the cells were fixed and negatively contrast-stained. Treatment with 6.4 mM delmopinol for 1 min resulted in marked ultrastructural changes of cell wall components and the outer cell membrane of the 3 gram-negative species compared with control cells, whereas the gram-positive streptococci treated with delmopinol showed little or no morphologic alteration as compared with untreated cells. The result from the electron microscopy was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins released from bacterial cells treated as for electron microscopy. More material was extracted from the gram-negative rods than from the gram-positive cocci. Significantly more delmopinol bound to the gram-negative rods than to the streptococci. It appears that the amphiphilic properties of delmopinol make gram-negative rods more vulnerable to delmopinol than gram-positive streptococci.

Aggregatibacter actinomycetemcomitans↗
PubMed1992

Effect of delmopinol on the cohesion of glucan-containing plaque formed by Streptococcus mutans in a flow cell system.

Glucan-containing plaque was formed by Streptococcus mutans adhering to saliva-coated glass slides in flow cells thermostated at 37 degrees C. The substrate was Brain Heart Infusion broth containing 1% sucrose and 10% sterile saliva. During the build-up of the plaque, which lasted for 29 h, the plaque was subjected to three two-minute exposures to either 0.1 mol/L sodium acetate buffer, pH 6.0, or the same buffer containing 6.4 mmol/L (0.2%) of the surface-active anti-plaque substance delmopinol hydro-chloride. The glass slides carrying the plaque were weighed, and plaques subjected to delmopinol treatment weighed only seven percent of the control plaques. The glass slides were then mounted in a beaker containing buffer, subjected to ultrasonication, and re-weighed. The delmopinol-treated plaques lost 59% of their wet weight upon sonication, while the controls lost only 19%. Control plaques having the same weight as delmopinol-treated plaques were not different from the control plaques grown for 29 h with regard to reduction of plaque weight after sonication. Transmission electron micrographs (TEM) showed a plaque dominated by globular or fibrillar matrix components in controls, while the delmopinol-treated plaque showed empty or unordered matrix areas between more densely packed cells. The TEM results were confirmed by scanning electron micrographs, which showed amorphous material associated with the bacterial cells in the control but not in the delmopinol-treated plaque. In conclusion, delmopinol reduced surface-associated glucan synthesis and lowered the cohesion of the plaque, indicating that glucan-containing plaque formed during repeated rinsings with delmopinol may be easier to remove by mechanical means than a non-treated plaque of this type.

Bacterial Adhesion↗
PubMed1991

Influence of delmopinol on bacterial zeta-potentials and on the colloidal stability of bacterial suspensions.

Delmopinol is a low molecular weight surface-active compound that has been shown to be effective against dental plaque both in vitro and in vivo and against gingivitis in vivo. To study the mode of action of delmopinol, the influence of the compound on the stability of bacterial suspensions, both with and without saliva, and on the zeta-potentials of oral streptococci was studied. The results showed that delmopinol reduced the magnitude of the zeta-potentials, but, in contrast, the colloidal stability of the bacterial suspensions without saliva was increased. The explanation of these observations could be that non-DLVO interaction components, such as repulsive hydration/steric forces, have come into effect at very close distances between two approaching bacterial cells. To judge from the present results, it is possible that delmopinol forms films on bacterial cells in a plaque, thereby facilitating mechanical removal.

Bacterial Adhesion↗
PubMed1989

Reduced forms of the iron-containing small subunit of ribonucleotide reductase from Escherichia coli.

The B2 subunit of ribonucleotide reductase from Escherichia coli contains a stable tyrosyl free radical and an antiferromagnetically coupled dimeric iron center with high-spin ferric ions. The tyrosyl radical is an oxidized form of tyrosine-122. This study shows that the B2 protein has a fully reduced state, denoted reduced B2, characterized by a normal nonradical tyrosine-122 residue and a dimeric ferrous iron center. Reduced B2 can be formed either from active B2 by a three-electron reduction in the presence of suitable mediators or from apoB2 by addition of two equimolar amounts of ferrous ions in the absence of oxygen. The oxidized tyrosyl radical and the ferric iron center can be generated from reduced B2 by the admission of air. The tyrosyl radical can be selectively reduced by one-electron reduction in the presence of a suitable mediator, yielding metB2, a form that seems identical with the form resulting from treatment of active B2 with hydroxyurea. 1H NMR was used to characterize the paramagnetically shifted resonances associated with the reduced iron center. Prominent resonances were observed around 45 ppm (nonexchangeable with solvent) and 57 ppm (exchangeable with solvent) at 37 degrees C. From the temperature dependence of the chemical shifts of these resonances it was concluded that the ferrous ions in reduced B2 are only weakly, if at all, antiferromagnetically coupled. By comparison with data on the similar iron center of deoxyhemerythrin it is suggested that the 57 ppm resonance should be assigned to protons in histidine ligands of the iron center.

Electron Spin Resonance Spectroscopy↗
PubMed1988

Soluble tyrosine hydroxylase (tyrosine 3-monooxygenase) from bovine adrenal medulla: large-scale purification and physicochemical properties.

A new procedure that permits large-scale purification of tyrosine 3-monooxygenase (tyrosine hydroxylase) (L-tyrosine,tetrahydropteridine:oxygen oxidoreductase (3-hydroxylating), EC 1.14.16.2) from the cytosolic fraction of bovine adrenal medulla is described. The homogenous enzyme revealed a subunit Mr of 60,000 and a specific activity of 425 nmol.min-1.mg-1. The N-terminal amino-acid sequence (27 residues) revealed 89% homology with the human pheochromocytoma enzyme as deduced from its cDNA sequence. The pure enzyme contained 0.66 +/- 0.09 mol iron, 0.13 mol zinc and 0.62 +/- 0.04 mol phosphate per mol subunit of Mr = 60,000. A broad light absorption band with its maximum around 700 nm (epsilon 700 nm = 1.3 (mM monomer)-1.cm-1) explains its blue-green color. EPR spectra at 3.6 K revealed high-spin Fe(III) (S = 5/2) in an environment of nearly axial symmetry (g values at 7.2-6.7, 4.7-5.3 and 1.9-2.0). A close correlation was observed between the absorbance at 700 nm and the intensity of the axial type of EPR spectrum. The absorption peak at 700 nm is compatible with a ligand-to-iron charge-transfer transition as a result of catecholate coordination to the iron. Physicochemical studies suggest that the enzyme does not undergo such major substrate- or cofactor-induced conformational changes as have been reported for the related enzyme, phenylalanine hydroxylase.

Adrenal Medulla↗