Biomedical subjects

T Karlsson

Publications and source records attributed to T Karlsson.

At least 19 recordsLinked to original sources

PubMed2006

Admission glycaemia and outcome after acute coronary syndrome.

BACKGROUND: Acute phase hyperglycaemia has been associated with increased mortality in patients with acute coronary syndrome. We investigated whether the predictive value of admission hyperglycaemia for mortality differs between diabetics and non-diabetics with acute coronary syndrome. METHODS: Patients with acute coronary syndrome (n=1957) were followed up prospectively for 45 months. Patients were stratified into quartile groups defined by admission plasma glucose and hyperglycaemia was defined as plasma glucose of >9.4 mmol/l, which was the cut-off value for the 4th quartile. The relationship between admission hyperglycaemia and short-term (< or =30 day) and late (>30 day) mortality was analysed. RESULTS: Of 1957 patients, 22% had a history of diabetes. Among patients without diabetes, those with hyperglycaemia had both a higher 30-day mortality rate (20.2% vs. 3.5%, p<0.0001) and late mortality rate (19.1% vs. 11.7%, p=0.007). Hyperglycaemic patients with diabetes had a higher late mortality rate than diabetic patients with plasma glucose of < or =9.4 mmol/l (29.3% vs. 14.9%, p=0.001). Of patients with hyperglycaemia at admission, those without diabetes had a higher 30-day mortality rate compared with those with diabetes (p=0.002). CONCLUSION: Admission hyperglycaemia is a strong risk factor for mortality in patients with acute coronary syndrome and may be even stronger than a previous history of diabetes. Hyperglycaemic patients without recognised diabetes have a higher short-term mortality risk than hyperglycaemic patients with known diabetes.

Aged↗

PubMed2006

Composition of coronary plaques obtained by directional atherectomy in stable angina: its relation to serum lipids and statin treatment.

OBJECTIVES: The stability and inflammatory activity in atherosclerotic plaques may be modulated by lipids and lipoproteins as well as the pleiotropic effects of statins. The aim of this study was to analyse the effect of statin treatment as well as the relation of plasma lipids and lipoproteins to tissue composition in atherosclerotic plaques. DESIGN: Patients with stable angina and coronary plaques suitable for directional coronary atherectomy (DCA) were randomized to atorvastatin (80 mg once daily) or placebo (29 randomized, 22 underwent DCA, 11/group). After an average treatment of 10 weeks, patients underwent DCA, tissue specimens were obtained, and the tissue composition was determined by immunohistochemistry. RESULTS: Atorvastatin reduced the T-cell content, but did not change lipid, collagen, smooth muscle cell, or macrophage content. Plasma levels of apolipoprotein AI (apoAI) correlated positively with tissue collagen and inversely with metalloproteinase-9 and macrophage content. About half the specimens contained neutrophil granulocytes. CONCLUSIONS: Short-term atorvastatin treatment tended to reduce the T-cell content of atherosclerotic plaques, indicating modulation of cell-mediated immunity. High plasma levels of apoAI correlated with increased collagen content and reduced inflammation, supporting the notion that plasma apoAI stabilizes atherosclerotic plaques. The significance of neutrophils in the lesions merits further study.

Adult↗

PubMed2006

Ammonium chloride and alpha-ketoglutaric acid increase glutamine availability in the early phase of induced acute metabolic acidosis.

BACKGROUND: Glutamine deficiency in critical illness is associated with increased morbidity and mortality. We hypothesized that ammonium chloride (NH(4)Cl) and alpha-ketoglutaric acid (alpha-KGA) infusions could increase glutamine availability possibly through de novo synthesis in the liver. METHODS: Anesthetized post-absorptive pigs were allocated to four groups (n = 8). The study groups received either a 4-h intravenous infusion of alpha-KGA, 11.4 micromol/kg/min and NH(4) (+), 9.7 micromol/kg/min (group 1), or alpha-KGA, 2.85 micromol/kg/min and NH(4) (+), 46.3 micromol/kg/min (group 2), or alpha-KGA, 11.4 micromol/kg/min (group 3), or isotonic saline (control group). Plasma concentrations of glutamine and glutamine exchange in liver, intestine and skeletal muscle were investigated. RESULTS: Plasma glutamine concentrations in group 1 (58% increase) were greater (P < 0.05) compared with the control group (14% decrease) and group 3 (13% decrease), and in group 2 (91% increase) compared with the control group, group 3 (P < 0.0001) and group 1 (P < 0.05). Intestinal glutamine extractions in group 2 were significantly greater (P < 0.01) compared with all other groups. Neither the liver nor the hind leg increased its release of glutamine. Arterial pH decreased (all P < 0.001) to 7.39 +/- 0.01 in the control group, 7.30 +/- 0.01 in group 1, 7.19 +/- 0.01 in group 2 and 7.35 +/- 0.01 in group 3. CONCLUSION: Infusions of alpha-KGA and NH(4)Cl, to a pH range of 7.20-7.30, did not enhance hind leg or hepatic glutamine release. The increased plasma concentrations of glutamine were effects of NH(4)Cl, not alpha-KGA, and caused either by de novo synthesis or decreased degradation.

Acidosis↗

PubMed2004

Influence of pericardial suction blood retransfusion on memory function and release of protein S100B.

BACKGROUND: To study the influence of pericardial suction blood (PSB) on postoperative memory disturbances and release patterns of protein S100B during and after cardiopulmonary bypass (CPB). METHODS: Sixty male patients admitted for coronary artery bypass surgery were prospectively randomized to receive PSB either by using conventional cardiotomy suction retransfusion or after cell-saver processing. RESULTS: The concentration of S100B rose during the period of CPB from 0.065 +/- 0.004 to 0.24 +/- 0.001 microg/L (p < 0.001). PSB contained 18.0 +/- 1.7 microg/L of S100B. Direct retransfusion from the cardiotomy reservoir made the systemic level increase to 1.42 +/- 0.19 microg/L compared to 0.25 +/- 0.02 microg/L using a cell-saver. Signs of postoperative memory dysfunction ( > 1 SD) were discovered in one of three tests, but were unrelated to technique of retransfusion. No associations were found between serum concentrations of S100B and memory function. CONCLUSION: In this study, retransfusion of PSB during cardiac surgery appeared not to cause memory disturbances. PSB contained high concentrations of protein S100B making its use as a marker of cerebral injury unsuitable.

Blood Transfusion, Autologous↗

PubMed2004

Breastfeeding, very long polyunsaturated fatty acids (PUFA) and IQ at 6 1/2 years of age.

AIM: Breastfeeding seems to be favorable for cognitive development. Could levels of polyunsaturated fatty acids (PUFA) explain this? METHODS: Pregnant mothers were recruited consecutively at maternity care centres. PUFA were analysed in colostrum and breast milk at 1 and 3 mo. The product-precursor ratios of n-6+n-3 PUFA were examined as measures of activity in respective steps in the fatty acid metabolic chain. Also, the quotient between DHA and AA was analysed. The children were tested with the full WISC-III at 6.5 y. RESULTS: First, the influence of length of breastfeeding was analysed by multiple regression together with relevant cofactors (except for PUFA). In the best models, 46% of the variation in total IQ was explained. Length of breastfeeding contributed significantly to total IQ (beta = 0.228, p = 0.021), verbal IQ (beta = 0.204, p = 0.040) and performance IQ (beta = 0.210, p = 0.056). There were no significant single correlations between PUFA and measures of cognitive development. However, in multiple regression analysis of colostrum, significant beta-coefficients were found for steps 4+5 in the fatty acid metabolic chain (beta = 0.559, p = 0.002). If length of breastfeeding and gestation week were added to steps 4+5, this three-factor model could explain 67% of the variation of total IQ. Introducing length of breastfeeding and gestation week together with the quotient DHA/AA (beta = 0.510, p < 0.001) yielded a three-factor model, which explained 76% of the variation in total IQ. CONCLUSION: Our findings could be interpreted as supporting the importance of high levels of PUFA for cognitive development. However, the sample is small and the results must be interpreted with caution.

Breast Feeding↗

PubMed2003

A study of homonuclear dipolar recoupling pulse sequences in solid-state nuclear magnetic resonance.

Dipolar recoupling pulse sequences are of great importance in magic angle spinning solid-state NMR. Recoupling sequences are used for excitation of double-quantum coherence, which, in turn, is employed in experiments to estimate internuclear distances and molecular torsion angles. Much effort is spent on the design of recoupling sequences that are able to produce double-quantum coherence with high efficiency in demanding spin systems, i.e., spin systems with small dipole-dipole couplings and large chemical-shift anisotropies (CSAs). The sequence should perform robustly under a variety of experimental conditions. This paper presents experiments and computer calculations that extend the theory of double-quantum coherence preparation from the strong coupling/small CSA limit to the weak coupling limit. The performance of several popular dipole-dipole recoupling sequences-DRAWS, POST-C7, SPC-5, R1, and R2-are compared. It is found that the optimum performance for several of these sequences, in the weak coupling/large CSA limit, varies dramatically, with respect to the sample spinning speed, the magnitude and orientation of the CSAs, and the magnitude of dipole-dipole couplings. It is found that the efficiency of double-quantum coherence preparation by gamma-encoded sequences departs from the predictions of first-order theory. The discussion is supported by density-matrix calculations.

Alanine↗

PubMed2003

Arousal increases baroreflex inhibition of muscle sympathetic activity.

AIM: Surprising sensory stimuli causing arousal are known to evoke short-lasting activation of human sympathetic activity in skin but not in muscle nerves. In fact, anecdotal observations suggest that muscle sympathetic activity may be inhibited. To test this hypothesis, the effects of surprising somatosensory (electrical skin pulses) or visual (flash) stimuli on multiunit muscle sympathetic activity were studied in 36 healthy subjects, aged 19-71 years. METHODS: The stimuli were given either 200 or 400 ms after the R-wave of the electrocardiogram. Dummy stimuli, consisting of trigger pulses without sensory stimuli, served as controls. RESULTS: On a group basis, a single sensory stimulus of either type attenuated the amplitude of one or two sympathetic bursts, while no such effects occurred after dummy stimuli. Individually, the inhibition was evoked by at least one stimulus modality or delay in 16 subjects, whereas in three subjects no significant inhibition occurred. Electrodermal signs of skin sympathetic activation were present in all subjects. Compared with one, five repeated electrical skin pulses induced only minor additional inhibition of muscle sympathetic activity, indicating marked habituation of the neural response. In nine subjects, the experiments were repeated once and in three subjects twice (with intervals of 2-3 months); in 11 of the 12 subjects, the sympathetic effects were reproducible. In the group of subjects without significant sympathetic inhibition the stimuli induced a small, transient increase of mean blood pressure, which was not present in the group with sympathetic inhibition. CONCLUSION: The finding that different sensory stimuli induce similar effects that habituate markedly on repetition suggests that the inhibition of muscle sympathetic activity is because of arousal. The interindividual differences in sympathetic and blood pressure effects may be part of interindividual differences in behavioural responses to stress.

Adult↗

PubMed2003

Quality assurance with regard to outcome and use of medical resources for patients hospitalized with acute chest pain: a comparison between a city university hospital and a county hospital.

This study aimed to test the hypothesis that there is a difference in mortality between patients hospitalized with acute chest pain in a university hospital and those hospitalized in a county hospital, and to describe differences in characteristics and use of medical resources in these two settings. All patients hospitalized at Sahlgrenska University Hospital in Göteborg (with a catchment population of 706 inhabitants/km(2)) and Uddevalla County Hospital (with a catchment population of 34 inhabitants/km(2)) with symptoms of acute chest pain during a registration period of 6 months were included in the study. A total of 1592 patients in the city hospital and 822 in the county hospital fulfilled the given criteria for inclusion. Patients in the urban area differed from those in the rural area in that they had a lower prevalence of previous angina pectoris and hypertension and a higher prevalence of previous cancer, previous percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass grafting (CABG) and current smoking. On admission to hospital, patients in the urban area less frequently showed clinical signs of congestive heart failure and acute ischaemia on the electrocardiogram (ECG) but more frequently had a pathological ECG without signs of ischaemia and more frequently had a heart rate >100 beats/min. The use of medical resources differed between the two hospitals. Revascularization was more frequent in the city hospital and the use of -blockers in the county hospital. The overall 30 day mortality was 4.7% in the urban area and 4.3% in the rural area (P=0.74). When correcting for differences at baseline, the risk ratio for death in the county hospital versus the city hospital was 0.84 (95% confidence interval 0.51-1.40, P=0.53). In conclusion, among patients hospitalized with acute chest pain in a city university and a county hospital the mortality during the subsequent 30 days did not differ. However, there were differences in terms of the use of medical resources and in previous history, chronic medication prior to hospital admission and status on admission between the two cohorts.

Acute Disease↗

PubMed2002

A stellar relic from the early Milky Way.

The chemical composition of the most metal-deficient stars largely reflects the composition of the gas from which they formed. These old stars provide crucial clues to the star formation history and the synthesis of chemical elements in the early Universe. They are the local relics of epochs otherwise observable only at very high redshifts; if totally metal-free ('population III') stars could be found, this would allow the direct study of the pristine gas from the Big Bang. Earlier searches for such stars found none with an iron abundance less than 1/10,000 that of the Sun, leading to the suggestion that low-mass stars could form from clouds above a critical iron abundance. Here we report the discovery of a low-mass star with an iron abundance as low as 1/200,000 of the solar value. This discovery suggests that population III stars could still exist--that is, that the first generation of stars also contained long-lived low-mass objects. The previous failure to find them may be an observational selection effect.

Journal Article↗

PubMed2002

Structural studies of biomaterials using double-quantum solid-state NMR spectroscopy.

Proteins directly control the nucleation and growth of biominerals, but the details of molecular recognition at the protein-biomineral interface remain poorly understood. The elucidation of recognition mechanisms at this interface may provide design principles for advanced materials development in medical and ceramic composites technologies. Here, we describe both the theory and practice of double-quantum solid-state NMR (ssNMR) structure-determination techniques, as they are used to determine the secondary structures of surface-adsorbed peptides and proteins. In particular, we have used ssNMR dipolar techniques to provide the first high-resolution structural and dynamic characterization of a hydrated biomineralization protein, salivary statherin, adsorbed to its biologically relevant hydroxyapatite (HAP) surface. Here, we also review NMR data on peptides designed to adsorb from aqueous solutions onto highly porous hydrophobic surfaces with specific helical secondary structures. The adsorption or covalent attachment of biological macromolecules onto polymer materials to improve their biocompatibility has been pursued using a variety of approaches, but key to understanding their efficacy is the verification of the structure and dynamics of the immobilized biomolecules using double-quantum ssNMR spectroscopy.

Amino Acid Sequence↗

PubMed2002

Double-quantum solid-state NMR of 13C spin pairs coupled to 14N.

We examine the double-quantum magic angle spinning NMR spectra of pairs of 13C nuclei coupled to one or more 14N nuclei. The experimental spectra of 13C(2)-glycine and glycyl-[13C(2)]-glycyl-glycine are used to demonstrate the sensitivity of the spectra to the orientation of 14N quadrupole interaction tensors and to the molecular torsional angles.

Carbon Isotopes↗

PubMed2002

Topical retinoic acid alters the expression of cellular retinoic acid-binding protein-I and cellular retinoic acid-binding protein-II in non-lesional but not lesional psoriatic skin.

Therapeutic retinoids have profound effects on psoriatic skin pathology but their interactions with various retinoid-binding proteins in lesional vs non-lesional skin have not been investigated. Using quantitative real-time PCR the mRNA expression of cellular retinol-binding protein I (CRBPI) and retinoic acid-binding protein I/II (CRABPI/CRABPII) was studied in psoriatic and healthy control (=normal) skin after 4 days of occlusive RA/vehicle treatment (n=6). Untreated psoriatic lesions showed a markedly elevated CRABPII/CRABPI ratio, while the CRBPI level was reduced in lesional and non-lesional skin as compared to normal skin. In RA-treated normal and non-lesional skin, the mRNA expression of CRBPI was unaltered while that of CRABPI and CRABPII was reduced by approximately 80% and increased approximately 5-fold, respectively, as compared to vehicle-treated skin. In contrast, lesional skin exposed to RA showed an almost 90% increase in CRBPI transcripts but unaltered expression of CRABPI and CRABPII, yet, the mRNA expression of several inflammatory mediators, e.g. inducible nitric oxide synthase, interferon-gamma and interleukin-1beta, was clearly reduced. Immunohistochemistry localized CRABPII to suprabasal keratinocytes in normal skin and revealed markedly elevated levels in lesional skin. RA treatment induced CRABPII protein expression in normal and non-lesional skin, to similar levels as in untreated lesions. The results indicate that the effects of RA differ in normal/non-lesional psoriatic skin and lesional skin. Whether the high expression of CRABPII in psoriatic skin lesions is due to increased amounts of endogenous retinoids in lesional skin or reflects an abnormal regulation of the CRABPII gene in psoriasis remains to be studied.

Administration, Topical↗

PubMed2002

Serum lipids, lipoprotein(a) level, and apolipoprotein(a) isoforms as prognostic markers in patients with coronary heart disease.

OBJECTIVE: Our objective was to study prognostic factors for death in patients with coronary heart disease (CHD), focusing on serum lipids and lipoproteins. DESIGN AND SUBJECTS: The study subjects were 964 patients with angina pectoris who underwent coronary angiography between 1985 and 1987. Follow-up, including survival and cause of death, was carried out in April 1998. RESULTS: A total of 363 patients died. Increasing age, diabetes and low levels of HDL cholesterol and of apolipoprotein (apo) AI were associated with increased risk of total mortality and cardiac mortality. In men, low levels of LDL cholesterol and of apoB were associated with increased risk of death, but not of cardiac death only; high levels of lipoprotein(a) [Lp(a)] were not associated with increased risk. In women, however, there was a trend towards increased risk with increasing Lp(a) levels (P = 0.054); the smallest isoform of apo(a) was associated with a twofold increase in risk. In women, but not in men, risk decreased with increasing molecular weight of the apo(a) isoforms. CONCLUSIONS: Amongst lipoprotein variables, low levels of HDL cholesterol and of apoAI and the presence of low-molecular weight isoforms of apo(a) are associated with increased risk of death in patients with CHD. Apo(a) isoforms and Lp(a) levels seem to be more important as risk factors amongst women. Low LDL cholesterol and apoB levels were associated with increased risk, but only in men. These findings demonstrate the importance of a gender-specific analysis of risk factors for CHD.

Adolescent↗

PubMed2002

Early enteral nutrition in the cardiothoracic intensive care unit.

BACKGROUND AND AIMS: Early enteral nutrition (EN) improves intestinal integrity, motility and immunocompetence. However, technical problems such as diarrhoea and gastric residual volumes are said to be associated with the method and have prevented its implementation. We have prospectively assessed clinical problems connected to early EN. PATIENTS AND METHODS: Seventy-three consecutive patients eligible for EN were assessed and observed until discharge from the intensive care unit (ICU) or until they resumed oral nutrition. They had surgery for coronary artery bypass grafting and/or valvular disease, thoracic or thoracoabdominal aortic aneurysms or other combined procedures. Two cardiac patients were not subjected to surgery. RESULTS: In 59/73 patients, EN was started within 3 days. EN was discontinued in half of the patients when they were able to feed themselves. Twelve patients vomited, one of them severely. Dislocation of the nasogastric tube occurred in 28 patients. The 15 patients with diarrhoea were treated with 2-6 broad-spectrum antibiotics during their ICU-stay. Out of 73, 40 patients did not show any gastric residual volume (GRV). GRV decreased during EN in 50% of the patients with fairly large or large residual volumes. The incidence of aspiration pneumonia was 10%. CONCLUSION: In the cardiothoracic ICU, individually adjusted early EN is feasible with few problems.

Adult↗

PubMed2001

Temporal evolution of the electric field accelerating electrons away from the auroral ionosphere.

The bright night-time aurorae that are visible to the unaided eye are caused by electrons accelerated towards Earth by an upward-pointing electric field. On adjacent geomagnetic field lines the reverse process occurs: a downward-pointing electric field accelerates electrons away from Earth. Such magnetic-field-aligned electric fields in the collisionless plasma above the auroral ionosphere have been predicted, but how they could be maintained is still a matter for debate. The spatial and temporal behaviour of the electric fields-a knowledge of which is crucial to an understanding of their nature-cannot be resolved uniquely by single satellite measurements. Here we report on the first observations by a formation of identically instrumented satellites crossing a beam of upward-accelerated electrons. The structure of the electric potential accelerating the beam grew in magnitude and width for about 200 s, accompanied by a widening of the downward-current sheet, with the total current remaining constant. The 200-s timescale suggests that the evacuation of the electrons from the ionosphere contributes to the formation of the downward-pointing magnetic-field-aligned electric fields. This evolution implies a growing load in the downward leg of the current circuit, which may affect the visible discrete aurorae.

Journal Article↗

PubMed2001

Modeling furanose ring dynamics in DNA.

Determination of the conformational flexibility of the furanose ring is of vital importance in understanding the structure of DNA. In this work we have applied a model of furanose ring motion to the analysis of deuterium line shape data obtained from sugar rings in solid hydrated DNA. The model describes the angular trajectories of the atoms in the furanose ring in terms of pseudorotation puckering amplitude (q) and the pseudorotation puckering phase phi. Fixing q, the motion is thus treated as Brownian diffusion through an angular-dependent potential U(phi). We have simulated numerous line shapes varying the adjustable parameters, including the diffusion coefficient D, pseudorotation puckering amplitude q, and the form of the potential U(phi). We have used several forms of the potential, including equal double-well potentials, unequal double-well potentials, and a potential truncated to "second order" in the Fourier series. To date, we have obtained best simulations for both equilibrium and nonequilibrium (partially relaxed) solid-state deuterium NMR line shapes for the sample [2' '-2H]-2'-deoxycytidine at the position C3 (underlined) in the DNA sequence [d(CGCGAATTCGCG)]2, using a double-well potential with an equal barrier height of U(0) = 5.5k(B)T ( approximately 3.3 kcal/mol), a puckering amplitude of q = 0.4 A, and a diffusion coefficient characterizing the underlying stochastic jump rate D = 9.9 x 10(8) Hz. Then the rate of flux for the C-D bond over the barrier, i.e., the escape velocity or the overall rate of puckering between modes, was found to be 0.7 x 10(7) Hz.

Carbohydrate Conformation↗

PubMed2001

[Primary PTCA or thrombolysis in acute myocardial infarction?].

In acute ST-elevation infarction two different reperfusion strategies--thrombolytic medication and acute coronary angiography--have proved to improve the prognosis. The clinical course for patients with ST-elevation infarction is described in relation to whether they received thrombolytic medication or underwent acute coronary angiography with the aim of mechanical revascularization. The one-year mortality was high (20 percent) regardless of treatment strategy. In terms of morbidity there were no clear differences between the two treatment groups.

Aged↗

PubMed2001

Relief of symptoms and improvement of health-related quality of life five years after coronary artery bypass graft in women and men.

BACKGROUND: Severe coronary artery disease can be successfully treated with coronary artery bypass graft (CABG), with considerable improvement in the symptoms of angina pectoris. Approximately three of four patients are free of ischemic events for 5 years; however, increased survival is demonstrated only in selected subgroups with advanced coronary artery disease, and this effect has not been established in elderly patients. HYPOTHESIS: The study was undertaken to determine the relief of symptoms and improvement in other aspects of health-related quality of life (QoL) during 5 years after CABG in women and men. METHODS: Patients who underwent CABG in western Sweden were approached prior to and 5 years after surgery. Health-related QoL was estimated with Physical Activity Score (PAS), Nottingham Health Profile, and Psychological General Well-Being Index. RESULTS: Women (n = 381) had a 5-year mortality of 17% compared with 13% for men (n = 1,619; NS). After 5 years, 1,719 patients (survivors) were available for the survey; of these, 876 (51%) answered the inquiry both prior to and after 5 years. Both women and men improved markedly and highly significantly, both with respect to symptoms and other aspects of health-related QoL. Women suffered more than men in terms of limitation of physical activity, dyspnea, chest pain, and others aspects of health-related QoL. There was a significant interaction between time and gender, with more improvement in men with regard to chest pain when walking uphill or quickly on level ground, when walking on level ground at the speed of other persons their own age, when under stress, and in windy and cold weather. For those parameters as well as for PAS, improvement was more marked in men than in women. In the other aspects of health-related QoL, there was no interaction between time and gender. CONCLUSION: Five years after CABG, limitation of physical activity, symptoms of dyspnea, and chest pain were reduced, and various aspects of health-related QoL had improved in both women and men. In general, women suffered more than men both prior to and after CABG; however, in some aspects the improvement was more pronounced in men. Because of the limited response rate, the results may not be applicable to a nonselected population who had undergone CABG.

Coronary Artery Bypass↗