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Biomedical subjects

L Ljunggren

Publications and source records attributed to L Ljunggren.

18 recordsLinked to original sources
PubMed2006

Real-time perfusion adenosine stress echocardiography versus myocardial perfusion adenosine scintigraphy for the detection of myocardial ischaemia in patients with stable coronary artery disease.

BACKGROUND: Real-time perfusion (RTP) contrast echocardiography using low mechanical index power modulation technique allows for simultaneous myocardial perfusion and wall motion analysis. RTP-adenosine stress echocardiography (ASE) could be an alternative to dobutamine-atropine stress echocardiography; more tolerable for the patients and possibly similarly accurate. We aimed to evaluate RTP-ASE for the detection of myocardial ischaemia, compared to 99mTc-sestamibi single-photon emission computed tomography (SPECT). METHODS: Patients with suspected coronary artery disease, admitted to SPECT evaluation, were prospectively invited to participate. Patients underwent RTP imaging (SONOS 5500) using infusion of Sonovue (Bracco, Milano, Italy) before and during ASE. Two separate readers performed off-line analysis of myocardial perfusion and wall motion by RTP-ASE. A perfusion defect was the principal marker of ischaemia. Wall motion assessment was used to evaluate ischaemia in segments with perfusion artefacts. Each segment was attributed to one of the three main coronary vessel areas of interest: the left anterior descending (LAD); the left circumflex (LCx) and the right posterior descending (RPD). Normal SPECT at stress was judged normal at rest. RESULTS: In 33 patients, 99 coronary territories were analysed by SPECT and RTP-ASE. SPECT showed evidence of ischaemia in 9 of 33 patients. For the detection of ischaemia, the overall level of agreement between RTP-ASE and SPECT was 92% in all segments. The level of agreement was 88% in LAD, 97% in LCx and 91% in RPD segments. CONCLUSION: Real-time perfusion-adenosine stress echocardiography using power modulation could be an accurate and feasible tool for evaluation of ischaemia in patients with suspected coronary artery disease. The results from this study need confirmation by a study of a larger patient sample.

Adenosine↗
PubMed2000

Calorimetry a method to be used to characterise pyrolytically decarboxylated bicarbonate and assess its stability at elevated humidities.

Microcalorimetry was used to characterise bicarbonate after treatment at high temperatures. By measuring the heat flow from a sample of bicarbonate at 100% relative humidity, the net exothermic contribution could be used to estimate the fraction of pyrolytically formed Na(2)CO(3). The enthalpy value corresponding to the heat of solution of Na(2)CO(3) was also applicable to a physical mixture of NaHCO(3)/Na(2)CO(3). However, from the characteristic peaks of the heat flow versus time curve, pyrolytically formed Na(2)CO(3) could be distinguished from that present in the physical mixture. The different bicarbonate batches of varying degree of pyrolytic decarboxylation were also observed at an elevated relative humidity of 54%. From these measurements it could be inferred that a decarboxylation of up to 4.5% could be allowed without any significant effect on the stability of bicarbonate at 54%.

Calorimetry↗
PubMed1992

Microcalorimetric studies on uraemic plasma.

The heat production by human plasma in healthy and uraemic subjects has been measured by direct isothermal microcalorimetry. The plasma from uraemic subjects displayed an increased heat production compared to that of normal plasma. The heat production by plasma from healthy subjects, but not by that from uraemic patients, was both proportional to the amount of thiol groups in the plasma and also to the oxidation of the thiol groups. The oxygen consumption of uraemic plasma was proportional to the heat production. The heat production by samples from uraemic patients was significantly correlated to the plasma concentration of creatinine, whereas no such correlation was found between the concentration of urea and heat production of such samples.

Adult↗
PubMed1991

Ellipsometric studies of plasma protein adsorption on membrane polymers for blood purification.

Description of ellipsometric studies on absorption of the human plasma proteins; albumin (HSA), immunoglobulin G (IgG) and fibrinogen (FGN) to polymer surfaces of polyamide, polysulphone, polyetherpolycarbonate and polyacrylonitrile copolymer. Thin layers of the polymers (20-30 nm) were cast onto silicon dioxide/silicon wafers by a spin-coating procedure. The variations observed in surface concentration and adsorption time of the proteins were significant in all four polymers investigated.

Acrylic Resins↗
PubMed1991

Microcalorimetric evaluation of blood compatibility of hemodialysis membranes.

The study was made in vitro of reactions elicited by contact of granulocytes suspended in autologous plasma with three polymers: polyacrylonitrile (AN); polyetherpoly-carbonate (PC), and regenerated cellulose (Cu). Alterations in basal metabolism and biological function of the human blood granulocytes induced by interfacial reactions were determined by direct microcalorimetry. The polymers, which are commonly used as membranes in artificial kidneys, were found to activate granulocytes to degrees which were inversely correlated with their response to zymosan. The compatibility of the granulocytes and each of the membranes was of the order: AN greater than PC greater than Cu.

Calorimetry↗
PubMed1991

In vivo comparative evaluation of hemodialysis tubing plasticized with DEHP and TEHTM.

The migration of plasticizers from blood lines was studied in 11 patients with chronic renal failure on hemodialysis for a period of six months. Di-2-ethylhexylphthalate (DEHP), the conventional plasticizer, was compared with tri-2-ethylhexyltrimellitate (TEHTM). A liquid chromatography method for quantitative determination of DEHP and TEHTM in human blood plasma is described. During treatment with tubing containing DEHP, the plasma level of DEHP rose from 0.10 micrograms/ml (less than 0.05-0.17 n = 11) to 0.70 micrograms/ml (0.30-1.6 n = 11). When the patients were changed to tubing containing TEHTM, the concentration of DEHP was below or close to the detection limit and TEHTM could not be detected. No adverse events of either tubing were found as regards acute toxic effects, performance or applicability.

Aged↗
PubMed1990

Portable closed loop feedback system for control of the blood glucose level in the pig.

To establish the difference in glucose consumption of healthy compared to diabetic pigs, a transportable system for the feedback control of insulin and glucose was used in conscious pigs. The system for controlling glucose levels, as well as glucose consumption, was easy to use and adjusted smoothly to rapid changes in insulin level. Five days prior to the first day of experiment, healthy animals were prepared with intravenous jugular catheters tunnelled subcutaneously to the neck. On the first day of experiment, measurements of glucose were continuously taken before and after food ingestion. The animals were rendered diabetic after 2 days using Alloxan and streptozotocin. The measurements were then repeated. To be able to obtain constant glucose levels of approximately 3 mmol during both fasting and postprandial periods requires only small glucose adjustment infusion in the diabetic pigs, as opposed to healthy ones. Using the described system, it would be possible to evaluate subclinical diabetes and control unstable diabetics with different therapeutic regimes.

Animals↗
PubMed1987

Production of an amino acid sequence-specific antiserum against human amyloid A (AA) and serum amyloid A (SAA) protein.

The hydrophilic nonapeptide Ser-Asp-Ala-Arg-Glu-Asn-Ile-Gln-Arg, identical with residues 59-67 of human amyloid protein A (AA) and serum amyloid protein A (SAA), was covalently bound via its carboxyl-terminal end to the carrier-protein keyhole limpet haemocyanin. The complex was injected subcutaneously into ten rabbits. All rabbits produced antisera which, unabsorbed, were specific for AA and SAA. The antisera and their isolated peptide specific antibodies were performance-tested and found to be excellent for demonstration of AA and SAA in immunoblotting and immunohistochemical techniques but unsuitable for immunoprecipitation. Since it is difficult to produce AA- and SAA-specific antisera by procedures earlier described and commercial supplies of good such reagents are unavailable, the easy production of sequence-specific such antisera will facilitate more extended studies of the corresponding antigens for diagnostic and scientific purposes.

Amino Acid Sequence↗
PubMed1984

Plasticizer migration from blood lines in hemodialysis.

Polyvinylchloride (PVC) is the most commonly used material for tubing in extracorporeal circulation. It is usually plasticized by the addition of di-2-ethylhexylphthalate (DEHP). The plasticizer is physically mixed into the PVC. The potential danger of DEHP migration into blood has been discussed. It has been suggested that the polyurethane (PUR) coating should reduce this transport. Eight different types of PVC tubing sets for hemodialysis were investigated for migration of DEHP. In general, they contained approximately 40% by weight of plasticizer. It was shown that approximately 60 mg plasticizer could be extracted from complete tubing sets during a 6-h period. The release rate of DEHP from the PUR coating compared with PVC was increased. The results show that in contrast to previously published information, PUR coating of PVC tubing is not an effective method for reducing migration.

Plasticizers↗
PubMedDate not supplied

Cystatin C: a new marker of biocompatibility or a good marker for the redistribution of LMW proteins during hemodialysis?

The mechanism(s) behind the larger relative increase of Plasma beta 2 microglobulin (P-beta 2m) than that of Plasma albumin (P-alb) during Cuprophan hemodialysis is disputed. To elucidate this phenomenon P-alb, P-beta 2m (MW 11,800) and Plasma cystatin (P-cC; MW 13,000) an inhibitor of cystein proteinases, were determined before and after a Cuprophan or polysulphone hemodialysis (4-7 hr, QB 200 ml/min) in 30 stable regular dialysis treatment (RDT) patients. Body weight (BW) decreased by 2.5 +/- 1.4% (mean +/- SD). P-alb, P-beta 2m and P-cC increased by 11.4 +/- 14.8%, 15.4 +/- 11.5%, and 22.1 +/- 14.3%, respectively, during Cuprophan dialysis. The relative increase of P-cC was larger than that of P-beta 2m (P less than 0.05) and that of P-alb (P less than 0.02). During polysulphone dialysis BW decreased by 4.1 +/- 1.8%. P-alb, P-beta 2m, and P-cC increased almost equally by 28.1 +/- 18, 26.5 +/- 19.2, and 26.8 +/- 14.4%, respectively. These results are hard to interpret. Is the increase in P-cC a new marker of biocompatibility or does it reflect the true shift of low molecular weight (LMW) proteins between the interstitial and the plasma volume during hemodialysis better than P-beta 2m? In vitro studies indicate that small amounts of both Serum beta 2m (S-beta 2m) and Serum cystatin C (S-cC) are adsorbed to or sieved through the Cuprophan membrane, findings which render the kinetics of LMW proteins during hemodialysis still more complex.

Biocompatible Materials↗