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Biomedical subjects

K Laursen

Publications and source records attributed to K Laursen.

At least 19 recordsLinked to original sources
PubMed2005

Recycling of an industrial sludge and marine clay as light-weight aggregates.

The geographical limitations of Singapore, its restricted natural resources and voluminous municipal and industrial waste streams, make environmental management a major challenge for the island state. In an attempt to find ways to reduce importation of raw materials and the waste sent to landfill, light weight aggregates were produced from marine clay and a CaF(2)-rich semiconductor industry sludge. Aggregates were produced in a bench-scale rotary kiln with three clay/sludge loadings (90/10, 70/30 and 50/50%). All three mixtures showed good bloating behavior during firing and the ceramic pellets (1-1.5cm diameter) had densities well below that required for light-weight aggregates. In the initial tests, the pore sizes of the aggregates were in general too large resulting in high water absorption. Comparisons between the composition of the two waste products and the aggregates showed a significant loss of fluorine (40-60%) during processing; a problem which may require flue gas treatment. Leach testing showed that the formed aggregates would not pose a human or environmental hazard in terms of fluorine mobilization.

Calcium Fluoride↗
PubMed2001

Enhancement of the sulfur capture capacity of limestones by the addition of Na2CO3 and NaCl.

The ability of Na2CO3 and NaCl to enhance the sulfur capture capacity of three limestones was evaluated via fixed-bed calcination and sulfation experiments. The tested limestones represent three different sulfation morphologies: unreacted-core, network, and uniformly sulfated. Treatment with aqueous or powdered Na2CO3 significantly increased the Ca-utilization for two stones which normally sulfate in an unreacted-core pattern (20% to 45%) and network pattern (33% to 49%). The increase was lower for the uniformly sulfated stone (44% to 48%). Na2CO3 treatment increased the number of macropores leading to uniform sulfation of all particles, nearly eliminating the normal strong dependence of utilization on limestone type and particle size. The effect of Na2CO3 is believed to be associated with formation of a eutectic melt which enhances ionic diffusion and accelerates molecular rearrangement of the CaO. Treatment with aqueous NaCl solution caused a decrease in utilization, probably due to formation of large grains and plugging of pores caused by formation of a large amount of eutectic melt. The effect of Na2CO3 is less sensitive than that of NaCl to the amount added and the combustion environment (temperature and gas composition). In addition, Na2CO3 neither promotes corrosion nor forms chlorinated byproducts, which are main concerns associated with NaCl. Thus, Na2CO3 appears to have significant advantages over NaCl for enhancement of limestone sulfur capture capacity in fluidized-bed combustors.

Adsorption↗
PubMed2000

[How do patients evaluate the newly introduced system of substituting prescriptions?].

In 1997 a new prescription system was introduced in Denmark. The pharmacist must now substitute the prescribed drug with a cheaper version either by a generic prescription (G-substitution) or by an original prescription (O-substitution) unless the prescribing doctor indicates that substitution is not allowed in the specific case. The purpose of this study was to obtain the patients' view on the new prescription system and to identify any related problems. The investigation was based on structured interviews. The interview guide was designed as a questionnaire, which was validated and tested before use. The response rate was 82%. The study showed that 84% of the patients were satisfied with the system and 85% of the patients thought that it should continue. Eighty-three percent of the patients had tried another version of the substituted medicine earlier. Out of these, 6% had experienced more side-effects from the substituted medicine, and 10% felt that the substituted medicine had a weaker effect. There was one case of erroneous medical treatment as a consequence of the substitution system. Only few problems such as more side-effects or less effect of the substituted medicine was experienced by the patients. It can be concluded that the patients in general are satisfied with the new prescription system.

Adult↗
PubMed2000

[How do pharmacists evaluate the newly introduced system of substituting prescriptions?].

In 1997 a new prescription system was introduced in the Danish health care system. The pharmacist must now substitute a prescription with a cheaper version of the drug (either generic or original) unless the prescribing doctor indicates that substitution is not allowed in the specific case. The purpose of this study was to evaluate problems of the system and obtain the pharmacists' views on the system. The study was based on questionnaires to a representative sample of 75 pharmacists (a quarter of Denmark's pharmacists). The response rate was 72%. Half of the pharmacists were dissatisfied with the system, which primarily was due to the excessive workload imposed. In spite of this, about half the pharmacists wanted the system to be continued, because the overall purpose of finding the cheapest drug for the patient is good. Nearly all pharmacists thought that analogue substitution (substitution between drugs with the same overall effects but obtained by different means) should not be introduced.

Adult↗
PubMed1993

Copper release from copper intrauterine devices removed after up to 8 years of use.

We studied the copper-releasing ability, weight and microscopic appearance of 2 copper-bearing intrauterine devices (IUDs), Copper-T Cu 200 (CuT) and Nova-T Cu 200 Ag (NovaT), after they had been in utero for up to 8 years. In addition, we studied whether IUDs removed from pregnant women showed different copper release. We found that IUD weight was a linear, negative function of duration of use, and that less than 20% of total copper would be released over a period of 8 years. The average copper-releasing ability was significantly higher for CuT than for NovaT (82.6 +/- 6.4 vs. 42.7 +/- 2.6 micrograms/day). The copper release was constant and thus unrelated to duration of use. Copper-releasing ability was similar in IUDs removed from pregnant and non-pregnant women. Fragmentation or minor defects only occurred in 3% of the IUDs and no correlation was found between deposits or corrosion and copper release rates. We conclude that CuT and NovaT both have constant copper release for at least 5-6 years and that the useful life-span probably can be prolonged to 6-8 years or more.

Copper↗
PubMed1990

[Double contrast arthrography as a screening method of suspected meniscal lesions].

On reevaluation after one year of experience with double-contrast-arthrography (DCA) we found in 83 consecutive patients with suspected meniscal lesion a true positive diagnostic frequency of 0.84, a true negative diagnostic frequency of 0.75, a true positive nosografic frequency of 0.87 and a true negative nosografic frequency of 0.70. This gives an increased diagnostic accuracy compared to the initial evaluation of the arthrografies. No complications of the examination were registered. As DCA demands fewer resources than arthroscopy, this method is suggested as a screening procedure in patients with possible tears of the menisci.

Adolescent↗
PubMed1989

The effect of incisional plastic drapes and redisinfection of operation site on wound infection following caesarean section.

In a randomized prospective multicentre study of post-caesarean wound infection among 1,340 women in eight hospitals, the effect of redisinfection of the skin around the incision before skin closure and the effect of adhesive skin drapes were investigated. The overall rate of wound infection with pus was 5.0% (range 3.5-8.9%). The study showed a reduction in postoperative wound infection associated with redisinfection (P = 5.5%), while no benefit from adhesive plastic drapes could be demonstrated.

Cesarean Section↗
PubMed1988

Prospective study of malabsorption induced risk of gall stone formation in relation to fall in plasma cholesterol.

The relationship between cholesterol in plasma and risk of gall stone formation was investigated in 210 obese patients who underwent jejunoileal bypass surgery and were free of gall stone disease at the time. Among 185, successfully reexamined on average 19 months after surgery, 26 (14%) developed gall stones. The fall in plasma cholesterol after surgery exhibited a U-shaped relation to risk of gall stone formation with a minimum risk around the average fall (2.6 mmol/l). This was confirmed by multivariate logistic regression analysis (p less than 0.01) taking into account other possible determinants. The relation was not significantly dependent on weight loss or ratio between jejunum and ileum left in function. The study suggests that malabsorption induced fall in plasma cholesterol is related to risk of gall stone formation by two oppositely working mechanisms, one enhancing and one reducing the risk.

Adult↗
PubMed1983

Ultrasonography, computed tomography, and cholescintigraphy in suspected obstructive jaundice--a prospective comparative study.

In order to compare their capacity to visualize the bile ducts, ultrasonography, computed tomography, and cholescintigraphy were performed in 56 consecutive jaundiced patients in whom extrahepatic cholestasis was clinically suspected. The predictions as to the patency of the large bill ducts were compared with the final diagnoses made on the basis of direct cholangiography together with autopsy, biopsy, operative findings, and the clinical course. Thirty-nine patients (70%) had obstructed bile ducts, and 17 (30%) had patent large bile ducts. Using a simple scoring scale with 112 points as the maximum, ultrasonography obtained 72 points, computed tomography received 56 points, and cholescintigraphy totalled 37 points. Nonsignificant trends were found in favor of ultrasonography as compared with computed tomography and of computed tomography as compared with cholescintigraphy (p greater than 0.05), whereas ultrasonography was significantly better than cholescintigraphy (p = 0.01). However, because computed tomography is expensive and may imply a higher number of secondary direct cholangiographies than ultrasonography, we recommend ultrasonography as the first choice for noninvasive bile duct visualization. Computed tomography is an alternative method, whereas cholescintigraphy cannot be recommended.

Cholangiography↗
PubMed1981

CT in retroperitoneal fibrosis.

Of 23 cases of surgically proven retroperitoneal fibrosis evaluated by computed tomography (CT), 11 were examined preoperatively, while 12 were examined by CT in a retrospective study. The fibrosis appeared as a prevertebral retroperitoneal mass or as a fibrous sheet covering the central vessels and the ureters in 15 patients. The CT appearance corresponded well with the surgical findings in these cases. CT failed to visualize the fibrosis in eight cases mainly when the fibrosis was limited to the pelvis surrounding the distal ureters. A combination of retroperitoneal fibrosis and aortic aneurysm was found in five cases. CT is considered valuable in the evaluation of patients wtih suspected retroperitoneal fibrosis. It gives direct information about the fibrosis and is usable also in uremic patients.

Adult↗
PubMed1981

Adrenocortical function compared with computed tomography of the adrenals in small cell carcinoma of the lung.

Autopsy in patients with pulmonary small cell carcinoma frequently reveals metastases to the adrenal glands. In order to test the hypothesis that CT scanning might demonstrate such metastases at the time of clinical diagnosis of the pulmonary disease, the results of adrenal CT in 15 patients were correlated to adrenocortical function tests. No statistically significant relationship was found. It is concluded that no reliable non-invasive method exists to diagnose adrenal metastases in patients with pulmonary small cell carcinoma.

Adrenal Cortex↗