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Biomedical subjects

T Sundqvist

Publications and source records attributed to T Sundqvist.

At least 73 records · Page 4Linked to original sources
PubMed1987

Regulation of the lateral diffusion of WGA-labeled glycoconjugates in human leukocytes. Comparison between adult granulocytes and differentiating promyelocytic HL60 cells.

The regulation of the membrane mobility of glycoconjugates in human polymorphonuclear leukocytes (PMNL) was studied by comparing adult PMNL with promyelocytic HL60 cells before and after stimulation of differentiation in HL60 cells with phorbol-myristate acetate (PMA) with respect to lateral diffusion of wheat germ agglutinin (WGA)-labeled glycoconjugates. For this purpose we developed a novel variant of microscope equipment for the study of fluorescence recovery after photobleaching (FRAP) and continuous fluorescence microphotolysis (CFM) using a mini-computer for handling of shutters, data acquisition, and calculations. This equipment is presented in the report. We found that PMA-induced differentiation in HL60 cells reduced the lateral diffusion coefficient (D) of WGA-labeled membrane entities from about 1.5 to 1.0 x 10(-10) cm2/s, which was close to that found for adult blood PMNL, i.e., 1-1.2 x 10(-10) cm2/s. The lateral mobility (D x 10(10)) of succinylated WGA (S-WGA) was 2.3 and 1.7 cm2/s in undifferentiated and PMA-differentiated HL60 cells, respectively, indicating that WGA might have cross-linked membrane receptors, resulting in the slower diffusion. The results are discussed in relation to the effect of phagocyte maturation on the mobility of membrane components.

Cell Line↗
PubMed1987

Fluorescence-linked immunosorbent assay (FLISA) for quantification of antibodies to food antigens.

Serum antibodies of the IgG type from rabbits immunized with food antigens (beta-lactoglobulin, ovalbumin and gliadin) have been quantified using a fluorescence-linked immunosorbent assay (FLISA), with the antigens adsorbed as round spots (about 8 mm in diameter) on glass or plastic microscope slides. The indirect immunofluorescence intensities were determined using a microscope fluorometer, and compared to enzyme-linked immunosorbent assay (ELISA) in microtiter plates and diffusion-in-gel-ELISA (DIG-ELISA) in plastic petri dishes. It was found that FLISA in general became more sensitive when the antigens had been adsorbed onto a plastic (Nunclon) than onto a glass surface. When the antigens were adsorbed to the plastic slides, the relative sensitivity order (maximum serum dilution) of the assays was in general the following, ELISA greater than FLISA greater than DIG-ELISA. The fluorescence-linked method appeared to require equal or less antigen and conjugated antiserum per sample. Due to the visual inspection of the surface, inhomogeneities of the antigen-coating could be readily discovered and evaluated by several measurements within the field of antigen-antibody reaction. It is proposed that spot FLISA may be an alternative to ELISA especially when the amount of antigen or antiserum is limited.

Allergens↗
PubMed1986

Gastrointestinal permeability in children with cow's milk allergy: effect of milk challenge and sodium cromoglycate as assessed with polyethyleneglycols (PEG 400 and PEG 1000).

Sixteen children with immediate-type cow's milk allergy were challenged with increasing amounts of cow's milk. Gastrointestinal permeability was investigated before and after challenge by the 6-hr urinary recovery of a mixture of different-sized polyethyleneglycols (PEG 400 and PEG 1000). The results were related to clinical symptoms in the individual patients. The majority of the children displayed changed permeability characteristics after the challenge, both with respect to the maximum uptake of a small test molecule (usually 370 dalton PEG) and/or a large molecule (1074 dalton PEG), and to size-dependent exclusion of probe molecules. When corrected for the dose of milk taken, the children showing the most severe immediate-type symptoms also displayed the greatest alteration of permeability. Treatment with sodium cromoglycate (SCG) before the challenge diminished the effect on the uptake of probe molecules, usually decreased the severity of elicited symptoms, allowing about a ten-fold increase in the milk dose. Cow's milk challenge in healthy children caused only minor permeability changes, whereas challenge in the sensitized subjects significantly changed (increased or decreased) the recovery of a large test molecule. The difference between healthy and allergic subjects was most obvious when correcting for dose of milk ingested. We conclude that oral challenge with cow's milk in allergic subjects affects the mucosal barrier, and peroral treatment with SCG moderates immediate hypersensitivity reactions with respect to both tolerated antigen dose and intestinal permeability properties.

Administration, Oral↗
PubMed1986

Intestinal permeability as assessed with polyethyleneglycols in birch pollen allergic children undergoing oral immunotherapy.

Twenty-four children with rhinoconjunctivitis due to birch pollinosis were treated in a double-blind manner with enteric-coated capsules containing either a high dose of a birch pollen preparation (n = 11) or placebo (n = 13). The permeability of the small intestine was analysed at three different occasions with a mixture of differently sized polyethyleneglycols (PEG 400 and PEG 1000), before the start of oral immunotherapy (OIT), at the moment of maximum allergen dose, and after 3 months of therapy which was at the beginning of the pollen season. The actively treated children did not significantly change their permeability characteristics as determined from PEG recovery in the urine. By contrast, in the control group of patients the recovery of larger PEG molecules was decreased after 3 months of therapy, possibly due to the commencing pollen season. In addition, small bowel biopsies were taken at the time of maximum allergen dose from two children openly treated with OIT. Both specimens were normal.

Administration, Oral↗
PubMed1986

Intestinal permeability in small children during and after rotavirus diarrhoea assessed with different-size polyethyleneglycols (PEG 400 and PEG 1000).

The permeability properties of the small intestinal mucosa was investigated in nine previously healthy children with acute diarrhoea due to rotavirus. The investigation was performed after intake of a mixture in water of polyethyleneglycol molecules (PEG 400 and 1000) ranging from 282 to 1250 dalton in molecular weight. The 6-h urinary recovery of the PEGs was determined with high performance liquid chromatography and used to assess the permeability characteristics of the intestine. The patients served as their own controls and were investigated in the same manner after recovery 3-5 weeks later. A significantly lower urinary recovery of PEG was noted for all molecular sizes (326-1206 dalton) during acute diarrhoea in comparison with the results obtained after recovery (p less than 0.001-0.1). There was also a relatively lesser change in the urinary recovery of larger PEG molecules during infection, as reflected by a higher recovery ratio between 1074 and 370 dalton PEGs. The results indicate profound changes in the permeability characteristics of the intestine during acute rotavirus diarrhoea.

Diarrhea, Infantile↗
PubMed1986

Acute yersinia infections in man increase intestinal permeability for low-molecular weight polyethylene glycols (PEG 400).

The passive intestinal permeability of patients with acute diarrhoea was investigated with a liquid meal of oral rehydration fluid containing differently sized, low-molecular weight polyethylene glycols (PEG 400). The recovery of test molecules was measured in 6 h specimens of urine. The subjects suffered from acute infections caused by yersinia bacteria accompanied by joint pains. They were investigated during the infection and at least 3-4 weeks later when they had recovered clinically. It was found that yersinia infections were associated with increased urinary recovery of PEG molecules, and with reduced restriction towards the larger PEG molecules. After the infection, the resorption of PEGs returned towards normal. Thus, the altered restriction of the gut wall towards the passage of probe molecules might help to explain the extraintestinal manifestations often seen in connection with these agents.

Acute Disease↗
PubMed1985

Blood flow in rat sciatic nerve during hypotension.

Laser Doppler flowmetry was utilized to examine blood flow in sciatic nerves of barbiturate-anesthetized and of unanesthetized decerebrate rats, in response to hypotension induced by graded exsanguination or by graded clamping of the descending aorta. Continuous laser Doppler flowmetry signals decreased linearly with decreasing arterial blood pressure. In anesthetized as well as in unanesthetized rats, the signal approached zero at a systemic blood pressure of 14 mm Hg or less. The results do not demonstrate autoregulation of blood flow in the rat sciatic nerve during systemic hypotension.

Anesthesia↗
PubMed1985

Spatial distribution of cell fluorescence determined with a diode-matrix (32 x 32 elements) and computer controlled epifluorescence microscopy.

A photodiode-matrix with 32 x 32 light-sensitive elements has been used to determine spatial fluorescence intensity of Rhodamine-labelled yeast cells (Saccharomyces cerevisiae). The matrix with electronics was built into one of the oculars of an epifluorescence microscope, and the fluorescence intensity scanned at intervals, determined from a desk-computer. The signals from one image were amplified and stored in a buffer-memory before being put into an auxiliary memory. The sensitivity of each element was calibrated, and linear regression used to determine true fluorescence intensity (256 levels). After background subtraction the spatial intensity was presented on a plotter either on a 0-9 scale, or on a three-dimensional plot (x-y-intensity). The effect of continuous UV-microphotolysis on the fluorescence of Rhodamine-labelled yeast was also determined.

Computers↗
PubMed1985

Gastrointestinal permeability in atopic and non-atopic mothers, assessed with different-sized polyethyleneglycols (PEG 400 and PEG 1000).

Gastrointestinal permeability was compared in seventy-one women, forty-six allergic and twenty-five non-allergic according to case history, by measuring the 6-hr urinary recovery after an oral load of different-sized polyethyleneglycols (PEG 400 and PEG 1000). Further classification, atopic and non-atopic, was obtained by skin-prick tests to inhalant and food allergens in sixty-four of the seventy-one mothers. No significant differences were observed between allergic and non-allergic women, neither regarding the maximum recovery nor the recovery ratio between a large and a small molecule. The results do not lend support to the hypothesis of a persistently increased gut permeability in atopic subjects, which in turn could possibly imply an increased risk of intrauterine sensitization of the foetus of an atopic mother.

Adult↗
PubMed1985

Modelling of intestinal permeability in man to polyethylene glycols (PEG 400 and PEG 1000).

The intestinal permeability barrier was evaluated in four healthy individuals by the 6 h urinary recovery of a mixture of different-sized polyethylene glycols (PEG 400 and PEG 1000) after a liquid meal of probe molecules. The mixture of PEGs contained around 25 different PEG polymers, ranging from about 194 to 1294 dalton in size. Three models were employed to get a condensed formulation of the intestinal barrier, namely a filter function, describing exclusion of molecules due to the molecular weight, and two expressions for ultrafiltration through a pore due to the Stoke-Einstein radius. A factor reflecting unrestricted passage of probe molecules in the size-range used was also included in the mathematical expressions. It was found that a filter function showing half-maximum exclusion at 589-956 daltons (Da) PEG and a pore function yielding a pore-size of 8.0-8.5 A equally well described the intestinal barrier in the four subjects. The results are discussed in relation to structures of the intestinal epithelium that may restrict the passage of molecules.

Capillary Permeability↗
PubMed1984

Concentration gradients in the under-agarose chemotaxis assay system with attractant surface adsorption.

To evaluate directional locomotion or chemotaxis of polymorphonuclear leukocytes (PMNL), assay conditions need to be understood quantitatively. The characteristics of the gradient of a chemoattractant in an assay system depend on, for example, the geometry of the system and the diffusion coefficient of the attractant, but since PMNL are able to respond to surface-bound attractants, surface adsorption of the attractant might also be a factor of importance. We have solved the diffusion equation to characterize the gradients present in the under-agarose assay system, when surface adsorption of the chemoattractant is taken into account. Application of the theory to experimental data shows that surface adsorption is important for the cellular response to the chemotactic factor generated from normal human serum, but not for the response to the chemotactic peptide fMLP.

Adsorption↗
PubMed1984

Intestinal permeability in healthy and allergic children before and after sodium-cromoglycate treatment assessed with different-sized polyethyleneglycols (PEG 400 and PEG 1000).

Gastrointestinal permeability was investigated in twenty-two children on two occasions, before and after treatment with sodium cromoglycate. The children were between 8 and 10 years old; half of them were classified as allergic according to history and laboratory tests, and half of them as healthy. The 6-hr urinary recovery of different-sized polyethyleneglycols (PEG 400 and PEG 1000) in combination with a mathematical model was used to assess the intestinal permeability barrier. No significant differences were seen in the first PEG test between healthy and allergic children, although those with gastrointestinal allergy showed a slightly lower, and those with other allergies a slightly higher recovery of the smaller PEGs than seen in the healthy individuals. After treatment with sodium cromoglycate, however, there was a significant decrease in uptake by allergic children, which could indicate that the permeability properties had returned to normal. The PEG method offers a simple, harmless and reproducible method to measure intestinal permeability properties. The change in permeability observed after sodium cromoglycate corresponds well with the clinical experience of usefulness of the drug in some children with food allergy.

Cell Membrane Permeability↗
PubMed1984

Acute infections with Giardia lamblia and rotavirus decrease intestinal permeability to low-molecular weight polyethylene glycols (PEG 400).

The passive intestinal permeability of patients seeking care for acute diarrhoea was investigated with a liquid meal containing differently sized, low-molecular weight polyethylene glycols (PEG 400; mol. wt. 282-590). The subjects suffered from acute infections caused either by Giardia lamblia or rotavirus. The patients were studied during infection and 3-4 weeks later when they had recovered clinically. It was found that both giardia and rotavirus infections were associated with decreased 6-h urinary recovery of the PEG molecules, particularly of the larger molecular weight species. After the infection, the permeability properties returned towards normal values. The results show that the permeability and the absorptive capacity is altered in patients with acute Giardia lamblia and rotavirus infections which could be important in relation to chronic infections and malnutrition attributed to these organisms.

Acute Disease↗
PubMed1984

Reduced intestinal permeability to low-molecular-weight polyethyleneglycols (PEG 400) in patients with jejunoileal bypass.

The intestinal permeation and 6-hour urinary recovery of small, multisized tracers, polyethyleneglycol 400 (PEG 400), was used to characterize gut permeability in nine patients after bypass surgery for morbid obesity and in ten healthy volunteers. In the patients, who also had hyperoxaluria, the urinary recovery of ingested PEG 400 was lower than in the healthy persons (10.9 and 24.7%). The patients also showed stronger intestinal exclusion of the larger polymers within the PEG 400.

Adult↗
PubMed1983

Lateral diffusion of wheat germ agglutinin-labeled glycoconjugates in the membrane of differentiating HL-60 and U-937 cells assessed with fluorescence recovery after photobleaching (FRAP).

The promyelocytic leukemia cell line HL-60 and the histiocytic cell line U-937 were grown in suspension culture. They were induced to differentiate during 5-d cultivation in the presence of dimethylsulfoxide (DMSO; 1.3% w/v) or phorbol-12-myristate-acetate (PMA; 10(-7) M), which yields granulocyte- and macrophage-like cells, respectively. Differentiation was evidenced by increased capacity to recognize and phagocytize IgG- or complement-coated yeast particles. Aliquots taken from the cultures with and without DMSO (or PMA) were spun down directly on glass microscope slides, washed, labeled with fluoresceinated wheat germ agglutinin (WGA), and directly examined at room temperature for the rate of fluorescence recovery after photobleaching (FRAP). It was found that cultivation of the HL-60 and the U-937 cells in the presence of DMSO, which yields granulocyte-like cells, reduced the average value of lateral diffusion coefficient D (X 10(10] from 1.72 +/- 0.13 cm2s-1 to 0.97 +/- 0.13 cm2s-1 and from 1.77 +/- 0.11 cm2s-1 to 0.82 +/- 0.13 cm2s-1, respectively. U-937 cells grown with PMA also showed a reduction of D(X 10(10] to 0.88 +/- 0.10 cm2s-1. There was a larger immobile fraction of fluorescence in the HL-60 cells than in the U-937 cells, viz., 70-80% compared to 10-50%. The total number of binding sites for WGA was not altered, but the surface density changed, since the HL-60 and the U-937 cells became smaller and larger, respectively, when grown in the presence of DMSO. It is concluded that differentiation reduces the average lateral mobility of the WGA-binding membrane component by a factor around 2.

Cell Differentiation↗
PubMed1983

Physicochemical properties and blood clearance of human serum albumin conjugated to different extents with dinitrophenyl groups.

Human serum albumin (HSA) conjugated to various extents with dinitrophenyl (DNP) groups and labelled with 125I was studied with regard to physicochemical properties and blood clearance after intravenous injection in mice. Increasing the degree of DNP conjugation increased the tendency to hydrophobic interaction, and increased the net negative charge. Heavily DNP-substituted HSA molecules tended to aggregate. The higher the degree of DNP substitution the faster was the conjugate eliminated from the circulation. Blood clearance was independent of serum complement, and was not affected by galactose, N-acetylglucosamine, mannose, alpha-methyl-D-mannoside, or fucose. It is proposed that the differences in blood clearance between the different DNP-HSA conjugates mainly depend upon differences in the tendency to hydrophobic interaction.

Animals↗