Biomedical subjects

K Magnusson

Publications and source records attributed to K Magnusson.

At least 19 recordsLinked to original sources

PubMed2006

Bioaccumulation of 14C-PCB 101 and 14C-PBDE 99 in the marine planktonic copepod Calanus finmarchicus under different food regimes.

Bioaccumulation factors (BAFs) were determined for (14)C-PCB 101 and (14)C-PBDE 99 in the pelagic copepod Calanus finmarchicus after exposure to either contaminated water or after being fed contaminated phytoplankton (the dinoflagellate Prorocentrum minimum or the diatom Thalassiosira weissflogii). BAFs in algae range from 7.6 to 8.0 for PCB 101 and from 8.5 to 8.6 for PBDE 99. BAFs in copepods were significantly lower, 6.3-6.8 for PCB 101 and 7.6 for PBDE 99. For each compound, the BAFs in copepods were independent of what algal species they had consumed, even though the bioaccumulation of both compounds were higher in P. minimum than in T. weissflogii. The ratios between BAF and the K(ow) for PCB 101 and PBDE 99 were similar within each of the three species, but varied between species. For copepods the ratios were 2-4, for T. weissfloggii 15-22 and for P. minimum 32-40. The data strongly suggest that the two compounds bioaccumulate in a similar manner and that there is no biomagnification in the transfer between phytoplankton and herbivorous copepods.

Animals↗

PubMed2006

Bioaccumulation of PCB congeners in marine benthic infauna.

Field concentrations of polychlorinated biphenyls (PCBs) were measured in sediment and nine marine soft bottom invertebrate species. Lipid- and organic carbon normalised biota-sediment accumulation factors (BSAFs) were determined for 29 nonplanar and 11 coplanar congeners. To investigate whether the bioaccumulation was in thermodynamic equilibrium with the sediment, the determined BSAFs were compared to theoretically calculated ones to obtain a BSAFdet./BSAFtheor-ratio. Large interspecific variations were found: one suspension feeding and one deposit feeding species of brittle stars (Amphiura filiformis and A. chiajei), and one predatory polychaete (Glycera rouxii) had ratios>1 for congeners with logKow>6.5. In these species there was also a linear relationship between logKow and BSAF, both for coplanar and for planar congeners but with lower values for coplanar ones. For other species the pattern was more scattered. Only the deposit feeding polychaete Melinna cristata had BSAFdet./BSAFtheor-ratios<1 for all congeners. Thus, the interspecific variations in bioaccumulation did not correlate with differences in feeding strategies, but may be caused by differences in biotransformation, and in age and size of the analysed specimens.

Age Factors↗

PubMed2004

Development and aging of N-methyl-D-aspartate receptor expression in the prefrontal/frontal cortex of mice.

The present study was designed to determine whether the changes that occur during aging in the expression of the N-methyl-D-aspartate (NMDA) receptor and two NMDA receptor subunits, zeta1 and epsilon2, are a continuation of developmental processes and whether protein and mRNA expression patterns of the subunits are similar across the lifespan. The prefrontal/frontal cortex of C57BL/6 mice of eight different ages (7-8, 13-15, 30-32, 49-53, and 70-72 days and 4.5, 11, and 25 months of age) were used to examine NMDA-displaceable [(3)H]glutamate binding and mRNA in tissue sections and mRNA and protein from homogenates. The lateral prefrontal/frontal cortex of C57BL/6 mice showed more significant declines in density of agonist binding to NMDA receptors during both development and aging than the medial cortex. Changes in mRNA expression for the epsilon2 subunit across the lifespan appeared to be related to the changes in NMDA receptor binding in the lateral cortex, even though the protein expression of the epsilon2 subunit did not show the same pattern of expression as the mRNA during development. The changes in epsilon2 subunit mRNA expression during adult aging may be a continuation of developmental processes, but there was also evidence that expression levels plateaued during early adulthood. The developmental expression of the zeta1subunit in the prefrontal/frontal cortex was influenced by gender and there was no significant effect of adult aging on either the protein or mRNA expression of this subunit. Determining how the expression of the NMDA receptor and its subunits change throughout the lifespan can help us to better understand the processes affecting the receptor during aging. These results should be useful for designing interventions into the aging process to repair or prevent changes in the NMDA receptor and its associated functions, such as learning and memory.

Aging↗

PubMed2002

Renal involvement in sarcoidosis--a report of 6 cases.

This report concerns 6 patients with renal involvement in sarcoidosis. Two of the patients had no clinical symptoms at all. In 3 patients, no extrarenal organ manifestation was found. All 6 patients had elevated levels of serum creatinine, 2 were hypercalcemic. Five patients manifested with mild proteinuria, but in none of the cases was a nephritic sediment with erythrocytes found. Kidney biopsies in 5 patients showed epitheloid cell granulomatous interstitial nephritis, and 1 patient presented with nephrocalcinosis. All patients were treated with corticosteroids. The serum creatinine levels decreased significantly in 4 patients (> 50% decrease), and slightly in 2 patients, elevated serum calcium levels were normalized. Thus, even in the absence of other organ manifestations, sarcoidosis can be the cause of renal insufficiency, and it responds well to corticosteroid treatment. These patients demonstrate the importance of kidney biopsy in the unexplained deterioration of renal function.

Adult↗

PubMed2001

The effect of TBT on the structure of a marine sediment comunity--a Boxcosm study.

The effect of tri-n-butyl tin (TBT) on an intact marine sediment community after five months exposure was investigated. Changes in the structure of macro- and meiofauna communities were determined, as well as the functional diversity of the microbial community using BIOLOG microplates for Gram negative bacteria. Development of tolerance in the microbial community was investigated using Pollution Induced Community Tolerance (PICT) experiments with fluxes of nutrients as effect indicators. TBT affected the structure and recruitment of the macro- and meiofauna at nominal additions of 30-137 micromol TBT/m2 sediment. Number of species, diversity, biomass and community similarity was reduced at these concentrations compared to control. Species that molt seemed to be the most tolerant since they were predominant in boxes that had received the highest TBT addition and echinoderms were the most sensitive species. Renewed addition of TBT in PICT experiments with sediment from each boxcosm showed that TBT had an effect on individual nutrient fluxes from all sediments. Analyses of the flux patterns revealed a memory of previous TBT exposure, either due to induced tolerance or other community conditioning.

Adaptation, Physiological↗

PubMed2000

A cross-over evaluation of different methods and devices to measure blood pressure in type 1 diabetic patients with nephropathy.

BACKGROUND: In type 1 diabetic patients with nephropathy, tight blood pressure control has been shown to prevent the progression of the disease. Up until now, self-monitoring, ambulatory and office blood pressure values have not been compared in these patients. Thus, we have evaluated blood pressure values obtained in the office by a physician and at home by self-monitoring with those measured under ambulatory conditions in these patients. Additionally, for blood pressure self-monitoring, three different devices (the sphygmomanometer, upper-arm oscillometer and wrist oscillometer) were compared. METHODS: Twenty-one treated hypertensive type 1 diabetic patients [age 45+/-9 years, duration of diabetes 33+/-12 years (mean+/-SD)] with overt diabetic nephropathy participated in this study. At both baseline and the end of the study, daytime ambulatory blood pressure measurement was performed. Office blood pressure was measured at baseline. Additionally, all the patients measured their blood pressure over a 3-week period using each of the three different devices, in random order, for 1 week. RESULTS: The mean office blood pressure values (135+/-21/85+/-12mmHg) were higher than both the ambulatory (131+/-23/80+/-12, P<0.05) and self-monitoring values (130+/-14/78+/-10; P<0.05 for systolic and P<0.02 for diastolic values). The difference between the ambulatory and self-monitoring values were not statistically significant. Diastolic blood pressure values measured with the oscillometric wrist device showed a trend towards higher values when compared to those measured with the sphygmomanometer and with the oscillometric upper-arm device (P=0.065 for diastolic values). CONCLUSION: Office blood pressure measurements may over-estimate blood pressure in patients with type 1 diabetes and diabetic nephropathy. Because the oscillometric wrist device tends to over-estimate diastolic values, upper-arm devices should be preferred for blood pressure self-monitoring in these patients.

Arm↗

PubMed1999

Atmospheric oxidation of poly(oxyethylene) alcohols. Identification of ethoxylated formates as oxidation products and study of their contact allergenic activity.

Ethoxylated alcohols are widely used as surfactants. In the present study we have continued our investigations on the degradation with time upon air exposure of the ethoxylated alcohols at normal storage and handling. As a result, a new group of ethoxylated formates with the general formula C12H25(OCH2CH2)nOCHO (n = 0-4) was identified in C12H25(OCH2CH2)5OH stored and handled at room temperature. To facilitate the identification work, reference compounds were synthesized. The formates showed no allergenic activity in the sensitization studies performed. In previous investigations on the same ethoxylated alcohol, we have identified formaldehyde and ethoxylated aldehydes among the oxidation products formed. Formaldehyde is a common contact allergen, and the ethoxylated aldehydes were shown to have a sensitizing capacity of the same magnitude as formaldehyde. The instability of the ethoxylated alcohols and formation of oxidation products may give an allergenic contribution to hand eczema caused by work with water and surfactants. To investigate the clinical significance in man an appropriate diagnostic patch testing in exposed humans is required.

Allergens↗

PubMed1999

A qualitative study to explore the experience of fatigue in cancer patients.

Fatigue--which is a complex, multicausal, and multidimensional subjective experience--is today the most frequently reported symptom from patients with cancer. The aim of this study was to explore the experience of fatigue in cancer patients and to describe the categories and dimensions of the symptoms. A qualitative method--grounded theory--was used. Unstructured, tape-recorded interviews with 15 cancer patients were used for data collection. The categories found in this study illustrate fatigue as a process. Three major categories were found: (1) experiences (of loss, need, malaise, psychological stress, emotional affection, abnormal weakness, difficulties in taking the initiative); (2) consequences (social limitation, affected self-esteem, affected quality of life); and (3) actions (coping). The categories were constructed on the basis of dimensions with subordinated qualities. Knowledge concerning the different expressions of fatigue is important in caring for patients with cancer. The results from this study may contribute to a better understanding of how a cancer patient can experience and express fatigue and how the symptoms may affect the patient.

Activities of Daily Living↗

PubMed1999

Are contact allergens stable in patch test preparations? Investigation of the degradation of d-limonene hydroperoxides in petrolatum.

Several of the products formed after oxidation of d-limonene exhibit strong contact allergenic properties. Some, e.g., the hydroperoxides, are unstable compounds. In this study, we have examined whether the limonene hydroperoxides are chemically stable in white petrolatum used for patch testing. We found that the stability of the hydroperoxides was strongly dependent on whether or not the petrolatum was stabilized with alpha-tocopheryl acetate. In the presence of this antioxidant, the hydroperoxides were degraded to a greater extent. The hydroperoxides were shown to be directly reduced to the corresponding alcohols by this agent. On the other hand, the compounds where shown to be stable in non-stabilized petrolatum throughout clinical patch testing for a period of 6 weeks, provided that the preparations were stored in a refrigerator when not used. Thus, it is recommended that vehicles without alpha-tocopheryl acetate are used when peroxy or hydroperoxy compounds are patch tested or used in sensitization experiments. However, it is important to limit the storage time so that optimal conditions are at hand. A fast method was developed to enable isolation and quantification of the hydroperoxides in white petrolatum. This analytical method may also be applicable to other compositions of patch test preparations.

Allergens↗

PubMed1998

Effect of semi-annual applications of a chlorhexidine/fluoride varnish mixture on approximal caries incidence in schoolchildren. A three-year radiographic study.

Development and progression of approximal caries is still difficult to prevent and control even in societies with declining caries prevalence. In this study, a test group of 115 12-yr old children were treated semi-annually with a mixture (1:1) of a varnish containing 0.1% F (Fluor Protector) and 1.0% chlorhexidine (Cervitec). A reference group of 104 children received fluoride varnish treatment (Fluor Protector) semi-annually. Approximal caries was recorded from bitewing radiographs at baseline and after 3 yr. At baseline, total decayed and filled surfaces (DFS) including enamel caries were 1.79+/-2.36 in the reference group and 2.0+/-2.77 in the test group. After 3 yr, the mean approximal caries incidence including enamel caries was 3.01+/-3.74 and 3.78+/-4.32, respectively. The differences at baseline as well as after 3 yr were not statistically significant. The results showed that both groups had a comparatively low incidence of approximal caries during the experimental period, and suggest that a mixture of fluoride and antibacterial varnish had no additional preventive effect on approximal caries incidence compared with fluoride varnish treatments alone.

Anti-Infective Agents, Local↗

PubMed1998

Formation of formaldehyde and peroxides by air oxidation of high purity polyoxyethylene surfactants.

Ethoxylated alcohols are non-ionic surfactants. The majority are used in household cleaners, laundry products, toiletries and in industrial and institutional cleaners. In previous studies, an ethoxylated non-ionic surfactant of technical quality showed allergenic activity in guinea pig experiments. Chemical analysis revealed a content of formaldehyde, a well-known contact allergen, and peroxides in the surfactant. Most cases of occupational contact dermatitis are considered to be of irritant origin, caused by contact with water and surfactants, but if allergenic autoxidation products can be formed, allergic contact dermatitis cannot be excluded. The sensitizing potential of a chemically defined high purity ethoxylated alcohol was investigated and oxidation under various storage and handling conditions was studied for this and a homologous product. The pure surfactant showed no significant allergenic activity on predictive testing in guinea pigs. When ethoxylated alcohols were stored in the refrigerator, their deterioration was limited. At room temperature, their content of peroxides and formaldehyde increased with time. Levels of formaldehyde above those capable of causing positive patch test reactions were found. Since such surfactants have wide applications, resulting exposure to formaldehyde could be more frequent than is generally realized, contributing to persistence of dermatitis in individuals allergic to formaldehyde.

Aerobiosis↗

PubMed1998

Insulin resistance and the effect of insulin on blood pressure in essential hypertension.

The aim of this study was to investigate the effect of 2 weeks of insulin administration on blood pressure and to simultaneously measure insulin sensitivity and insulin-induced vasodilatation in obese hypertensive patients. In a prospective, randomized, double-blind, crossover study (study 1), 23 obese, untreated, nondiabetic, hypertensive patients received either neutral protamine Hagedorn (NPH) insulin (0.3 U/kg body wt per day) or placebo subcutaneously for 2 weeks (washout period, 2 weeks). Office and 24-hour blood pressure values were measured at the beginning and end of each treatment period. In an open-label study (study 2), 8 obese hypertensive patients and 10 healthy control subjects underwent a 3-step hyperinsulinemic, euglycemic glucose clamp (step 1, 0.5; step 2, 2.5; step 3, 5.0 mU x kg(-1) x min(-1) [120 minutes each]). Leg blood flow (LBF) was measured by venous occlusion plethysmography. Insulin administration decreased mean+/-SD office blood pressure from 131+/-13 to 128+/-12 mm Hg (placebo, 132+/-13 and 132+/-13 mm Hg; P<0.05 between final examinations) and mean+/-SD 24-hour blood pressure by -3.3+/-6.9 mm Hg (placebo, +0.7+/-4.6 mm Hg; P<0.05). Insulin infusion increased LBF significantly in the healthy controls but not in obese insulin-resistant hypertensive subjects. Obese hypertensive patients are resistant to the effects of insulin with regard to both glucose uptake and vasodilatation. Administration of insulin exerts a small blood pressure-lowering effect in these patients. These data strongly argue against the postulated pressor action of insulin in essential hypertension.

Administration, Cutaneous↗

PubMed1998

Approximal caries development following intensive fluoride mouthrinsing in teenagers. A 3-year radiographic study.

Caries development on approximal surfaces was studied in 139 adolescents for a period of 3 yr. A test group was randomly sampled (n=69) and subjected to a new intensive mode of fluoride (F) mouthrinsings using 10 ml of 0.045% NaF neutral solution once a day for 3 d, twice a year in all, i.e., 6 rinses per year. A control group (n = 70) rinsed in a similar mode using fluoride-free tap water. The two groups received the same basic prophylactic program during the trial. Detection of approximal caries lesions and fillings was based on bitewing radiographs at baseline and after 3 yr. The test group developed an average of 2.75 + 4.76 (mean +/- SD) approximal DFS compared with 3.21 + 4.74 DFS in the control group (n.s.). However, among those teenagers who were caries free (DFS = 0) at baseline, the incidence of approximal carious and filled surfaces was 1.76+/-4.52 in the F-rinsing group (n = 26) compared with 2.76+/-5.01 DFS in the control group (n = 32), a 36% caries reduction which was statistically significant. The intensified mouthrinsing procedure seems to be a promising prophylactic mode for collective caries prevention.

Adolescent↗

PubMed1997

BIACORE analysis of histidine-tagged proteins using a chelating NTA sensor chip.

While BIACORE instruments are routinely used for kinetic measurements and for the determination of binding constants, the immobilization of a ligand onto the sensor chip surface has to be individually optimized for every system. We show here that the histidine (His) tag, routinely used in protein purification and in detection is an ideal tag for immobilization, despite the intrinsically low affinity between an immobilized metal ion and the His tag. This is due to strong rebinding effects caused by the high surface density of immobilized Ni2+-nitrilotriacetic acid (NTA) on the chips used here. The immobilization of the ligand can be adjusted to a low level using the same chip, such that mass transport limitation and rebinding of the analyte to the immobilized ligand is minimal. Nine different proteins with different numbers of His tags were tested for stable binding to the Ni2+-NTA surface. Most proteins with one His tag dissociate very rapidly from the Ni2+-NTA surface, and the KD for the interaction between His tag and Ni2+-NTA was estimated to about 10(-6) m at neutral pH. In contrast, two His tags are usually found to be sufficient for stable binding. The kinetics of the chaperonin system of Escherichia coli GroEL and GroES were analyzed as a model using this system and found to be very similar to those obtained with covalently immobilized ligands. The sensor chip can be reused many times, because of the powerful regeneration methods. The ligand can be freshly immobilized after each cycle, thus eliminating potential denaturation upon regeneration as a source of error.

Adenosine Triphosphate↗

PubMed1997

[The role of metabolic control in diabetes mellitus].

Diabetic nephropathy and microangiopathy as the complications of type 1 diabetes mellitus play a major role in determining the increased mortality. Intensified insulin therapy and adequate teaching and treatment programs are the most important steps to prevent the occurrence and progression of diabetic complications. Near-normalisation of metabolic control results in life expectancy which is comparable to the reference population.

Adult↗

PubMed1997

Swedish nurses' estimation of fatigue as a symptom in cancer patients--report of a questionnaire.

Many studies show that chronic fatigue is the most frequently reported symptom related to cancer and its treatment. In order to evaluate the problem in Sweden, a questionnaire was mailed to 442 registered nurses in the autumn of 1995 with the aim of determining cancer nurses' views of the nature and causes of cancer-related fatigue and which, if any, nursing interventions they employed in the management of this problem. The response rate was 49%. The responses showed that these nurses regarded fatigue as the most common symptom in cancer patients, but there were few established nursing interventions. Also, nurses wanted further education and tools for evaluation of fatigue, its causes and treatment.

Attitude of Health Personnel↗

PubMed1997

Contact allergenic activity of Tween 80 before and after air exposure.

Tween 80 is an ethoxylated hydrophilic non-ionic surfactant, which is used for the preparation of oil-in-water emulsions in pharmaceutical products, cosmetics, and industrial detergents. Ethoxylated surfactants are polyethers and are thus easily oxidized by atmospheric oxygen to a variety of hydroperoxides, peroxides and carbonyl compounds. The aim was to investigate the formation of oxidation products and the allergenic potential of Tween 80 before and after air exposure. The formation of peroxides and formaldehyde was followed with chemical analyses during air and pure oxygen exposure of water solutions of Tween 80 of technical quality. A complex mixture of compounds was formed when Tween 80 was oxidized. Formaldehyde was detected in amounts that may be eliciting in allergic individuals. Acetaldehyde was identified in Tween 80 before oxygen exposure, whereafter the amount gradually decreased. The contact allergenic activity was determined in experimental sensitization studies in guinea pigs. Non-oxidized as well as oxidized Tween 80 of technical quality showed allergenic activity. The results indicate that allergens are present in Tween 80 before oxidation and that new allergens are formed in the oxidation process. No obvious dose-response relationship was found in the sensitization studies. The possibility that allergenic compounds can be formed during storage and handling of products containing ethoxylated surfactants should be taken into consideration.

Acetaldehyde↗

PubMed1996

Difference in testosterone sensitivity in male spontaneously hypertensive (SHR) and Wistar-Kyoto rats (WKY).

The effects of castration and testosterone substitution on copulatory behavior and arginine-vasopressin (AVP) concentrations in the lateral septum (LS) were compared in the male spontaneously hypertensive rat (SHR) and its normotensive counterpart, the Wistar-Kyoto rat (WKY). The copulatory behavior was attenuated in the intact SHR and remained for a shorter time after castration than in the WKY males. A higher dose (1 mg/kg) of testosterone propionate (TP) was required in the castrated SHR to reestablish the copulatory behavior compared to the WKY (0.5 mg/kg). Following castration the main decline of AVP concentrations occurred over a period of 28 days. On postcastrational day 14, a time when approximately 50% of the initial AVP concentration remained, the decrease in the LS AVP content of the SHR surpassed that of the WKY. A dose-dependent increase of the AVP concentrations was achieved after 3 weeks of TP treatment (0.5 and 1.0 mg/kg, SC), which commenced 28 and 56 days after castration. The increase of AVP concentrations in the LS after a submaximal dose of TP (0.5 mg/kg) was less in the SHR than in the WKY. It is concluded that the gonadal hormone control of the copulatory behavior and AVP content in the terminal fields of the LS is characterised by a lower sensitivity in the SHR compared to the WKY. The data suggest that the low responsiveness to testosterone in the SHR comprises hypothalamic as well as extrahypothalamic neurons.

Animals↗