PubMed Health⌕ Search

Biomedical subjects

K Nyholm

Publications and source records attributed to K Nyholm.

At least 19 recordsLinked to original sources
PubMed2004

Polarization spectroscopy applied to the detection of trace constituents in sooting combustion.

The potential of polarization spectroscopy for the detection of trace constituents in sooting combustion was investigated. It was demonstrated that the directionality of the polarization spectroscopy signal can be exploited to efficiently suppress incoherent interferences, e.g., Rayleigh scattering at soot particles. We also show how polarization spectroscopy compares with laser-induced fluorescence in this type of environment by applying both techniques to atmospheric-pressure, premixed propane/oxygen flames. The acquired signals were spatially resolved along the centerline of the flame, and measurements were conducted at several heights above the burner head and for medium to very high fuel-to-oxidizer ratios. Through our work we found that polarization spectroscopy can be applied even in the presence of large soot fractions. For most conditions, where laser-induced fluorescence suffered from interferences like elastic scattering, spatially filtered polarization spectroscopy signals were virtually background-free, and only for high soot loads did a noticeable background on the latter signal appear. This background likely stems from Mie scattering at very large soot particles.

Journal Article↗
PubMed2000

The influence of lipophilicity on binding of boronated DNA-intercalating compounds in human glioma spheroids.

Five boronated DNA-intercalating compounds [5-ortho-carboranyl phenanthridinium (5-o-CP), 5-para-carboranyl phenanthridinium (5-p-CP), 6-para-carboranyl phenanthridinium, water-soluble boronated phenanthridinium and water-soluble boronated acridine (WSA1)], primarily developed for boron neutron capture therapy (BNCT), were analysed regarding their binding in cultured human malignant glioma spheroids. Comparisons were made with the corresponding DNA intercalators ethidium bromide and acridine orange. Octanol/phosphate buffered saline-water coefficients were determined for all compounds, and it was found that the most lipophilic (5-o-CP and 5-p-CP) were most toxic and accumulated high amounts of boron in monolayer cells. These compounds bound primarily in the outermost part of spheroids with poor penetration into the inner region, even after 2 days of continuous exposure. On the other hand, the most hydrophilic compound (WSA1) showed lower toxicity and lower boron accumulation in monolayer cells, and rapid binding in the inner region of spheroids. A reasonable explanation for this observation is that the lipophilic compounds interact mainly with lipophilic parts of the cells, like cellular membranes, and therefore rapidly binds to cells, preventing penetration and binding to cells in the deeper region of the spheroids. The possibility of using these compounds for BNCT are discussed.

Acridines↗
PubMed1995

Comparisons of selenite and selenium yeast feed supplements on Se-incorporation, mastitis and leucocyte function in Se-deficient dairy cows.

The dairy cows at the Estonian Agricultural University appeared to have an extremely low selenium status. The selenium level was 5.6 micrograms/l in whole blood and 3.2 micrograms/l in milk, on average. The blood glutathione peroxidase was consequently extremely low. The effects of organic selenium (selenized yeast) and sodium selenite were compared in a feeding experiment on 100 dairy cows. Selenium incorporation, udder health and the in vitro function of blood neutrophils were monitored. Supplementation of the feed either with 0.2 ppm organic selenium or sodium selenite for 8 weeks, increased the blood selenium level (geometric mean) within this period from the back-ground level (about 5.6 micrograms/l) to 167 (Se-yeast) and to 91 micrograms/l (selenite). The respective change in whole blood glutathione peroxidase (GSH-PX) was from 0.22 to 3.0 (Se-yeast) and to 2.3 (selenite) microKat/g Hb. Blood GSH-PX continued to increase up to 10 weeks after the supplementation was stopped. The bioavailability of yeast selenium was superior to selenite: the relative bioavailability (selenite = 1) of yeast selenium was 1.4 if blood GSH-PX, 1.9 if blood selenium, and 2.7 if milk selenium was used as the response criterion. Selenium-supplementation showed a positive effect on udder health. The percentage of quarters harbouring mastitis pathogens dropped from 22.9 to 13.0 in the Se-yeast group and from 18.4 to 7.4 in the selenite group during the supplementation period. The effect of selenium on mastitis was also reflected as a decrease in the output of milk somatic cells and N-acetyl-beta-D-glucosaminidase (NAGase). The time-luminescence profile of zymosan-induced activity of blood neutrophils became skewed to the left in Se-supplemented cows.

Acetylglucosaminidase↗
PubMed1995

D-dimer improves the prognostic value of combined clinical and laboratory data in equine gastrointestinal colic.

The discriminating ability of 15 parameters alone or in combinations, including results from analysis of plasma endotoxin, the Nycomed plasma D-Dimer test and phospholipase A2, were analyzed to predict morbidity and mortality in equine gastrointestinal colic. Endotoxaemia was a characteristic feature of the colic horses. The problem of adequately predicting nonsurvivors among colic horses required several parameters to be included in the logistic model: if the "classical parameters", (heart rate, respiratory rate, PCV, anion gap) were included in the model, addition of plasma D-dimer, phospholipase A2, and Cl- significantly improved the predictive value of the logistic model. Increasing heart rate and D-dimer together with decreasing chloride was a risk factor for nonsurvival. The sensitivity of this three-parameter logistic model to predict nonsurvival was 78% and specificity 77%. The Nycomed D-Dimer test is recommended as a horse-site test to predict disseminated intravascular coagulation and nonsurvival in equine colic.

Animals↗
PubMed1993

Urinary excretion patterns of pseudouridine and beta-aminoisobutyric acid in patients with tumours of the urinary bladder.

The preoperative and postoperative values of urinary pseudouridine:creatinine (phi:C) and beta-aminoisobutyric acid:creatinine (beta AIB:C) were estimated, in 192 patients with urothelial tumours of the bladder, 92 of whom had not previously been diagnosed. Urinary phi:C ratio correlated with the grade of tumour cell dysplasia (being highest in dysplasia grade 3), and to a lesser extent with the clinical stage. The treatment had no major influence on the excretion ratios. Decreased ratios, or those within the reference range, were associated with a better prognosis than increased ratios, and if both were increased at the same time the risk for progression of the disease was high. The biological tumour markers pseudouridine and beta-aminoisobutyric acid may be helpful in the diagnosis of tumours in the upper urinary tract, and in the follow-up of patients with tumours of the bladder.

Adult↗
PubMed1976

Studies of transitional cell tumours of the bladder. Prognosis and causes of death.

Transitional cell tumours of the bladder from a total of 228 patients were histologically classified as papillomas, papillomatous carcinomas and non-papillomatous carcinomas. Each group was subdivided into four grades of dysplasia. Papillomas and papillomatous carcinomas occurred in younger patients at a higher rate than non-papillomatous carcinomas. The 5-year-survival of patients with papillomas and carcinomas was 70 per cent and 26 per cent, respectively. Among patients with papillomas with dysplasia grades 1 and 2 the survival rate was almost identical. In the group of patients with papilloma thrombo-embolic diseases were the most common cause of death. Carcinoma of the bladder developed in about 30 per cent of the patients in this group. Recurrence of the papilloma only rarely changed the grade of dysplasia. If the recurrence was in the form of a carcinoma, an increase in the grade of dysplasia was common. The survival was more favourable among patients with carcinoma dysplasia grade 2 than among those with dysplasia grade 3. The rate of survival was higher in the group of patients with papillomatous carcinoma than among patients with non-papillomatous carcinomas. Among the decreased patients with primary carcinomas, 77 per cent died with carcinoma of the bladder. To a certain degree, the grade of tumour cell dysplasia seems to be an expression of the malignancy of the tumours. The duration of the disease and the appearance of tumours (papillomatous, non-papillomatous) may have relation to the patients' "defence" system. At autopsy, the papillomatous and non-papillomatous carcinomas were found to be similarly disseminated regardless of the difference in survival rate.

Adult↗
PubMed1975

Studies on tryptophan metabolism in Danish bladder cancer patients.

Urinary excretion of metabolites of the kynurenine pathway before and after a loading dose of 2 g L-tryptophan was studied in 31 bladder cancer patients from the Copenhagen area. Only 2 patients (6 per cent) showed abnormal tryptophan metabolism, and both patients excreted increased amounts of only 3-hydroxykynurenine after a loading dose of 2 g L-tryptophan. The percentage of bladder cancer patients with abnormal tryptophan metabolism is compared with the percentage found in other parts of the world. It is suggested that these findings may indicate that tryptophan metabolites do not play a major role in the genesis of bladder cancer among bladder cancer patients from the Copenhagen area. Other etiologic factors should be looked for.

Denmark↗