Tommy Olsson

Leptin is a risk marker for first-ever hemorrhagic stroke in a population-based cohort

BACKGROUND AND PURPOSE Leptin, important for body weight regulation, may be involved in the pathogenesis of the insulin resistance syndrome, associated with cardiovascular disease. We tested to determine whether leptin is a risk marker for first-ever stroke in a nested case-referent study. METHODS We identified 113 patients with first-ever stroke (94 with ischemic and 19 with hemorrhagic stroke) who, before the stroke, had participated in population-based health surveys in northern Sweden. Referents were matched for sex, age, date and type of health survey, and geographic region. Blood pressure (BP), body mass index (BMI), and presence of smoking, diabetes, and hypertension were recorded. Total cholesterol, insulin, and leptin were analyzed in stored samples. Risk markers for first-ever stroke were analyzed by conditional logistic regression analysis. RESULTS Patients with hemorrhagic stroke had higher levels of BMI and systolic and diastolic BPs. Leptin levels were 72% and 59% higher in males and females, respectively, with hemorrhagic stroke versus referents. Patients with ischemic stroke more often had hypertension, diabetes mellitus, and higher fasting glucose and insulin levels. A diagnosis of hypertension and elevated systolic and diastolic BPs were significant risk markers for first-ever hemorrhagic stroke in univariate analysis. High leptin (OR=20.55; 95% CI, 1.12 to 376.7) levels together with hypertension (OR=16.28; 95% CI, 1.49 to 177.3) remained as significant risk markers in a multivariate model. The combination of high leptin and high systolic or diastolic BP were associated with a profoundly increased risk for hemorrhagic stroke (OR=22.11; 95% CI, 1.57 to 310.9). Diabetes, hypertension, and obesity (BMI >/=27), together with high levels of insulin, glucose, systolic and diastolic BP, were significant risk markers for first-ever ischemic stroke in univariate analysis. Hypertension (OR=2.10; 95% CI, 1.14 to 3.86) remained as an independent risk marker in a multivariate model. CONCLUSIONS Plasma leptin is strongly associated with an increased risk for first-ever hemorrhagic stroke, independent of other risk markers for cardiovascular disease. Leptin may be an important link in the development of cardiovascular disease in obesity.

Plant uptake of major and minor mineral elements as influenced by soil acidity and liming

This study reports effects on soil solution chemistry and plant uptake of 55 elements (Ag, Al, As, B, Ba, Be, Bi, Br, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Fe, Gd, Ge, Hf, Hg, Ho, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, P, Pb, Pr, Rb, S, Sb, Sc, Se, Si, Sm, Sr, Tb, Th, Tl, U, V, W, Y, Yb, Zn, Zr) by raising the pH using addition of fine-grained precipitated calcium carbonate at 20 rates (yielding a soil solution pH range of 5.2 – 7.8) to A horizon samples of an acid Cambisol, cultivating a common grass (Agrostis capillaris L.) and determining the soil solution, root and shoot concentrations of these elements at the end of the experiment. For many of these elements, there is little or no previous information about concentrations in soil solutions, or in plant biomass, as related to soil pH/acidity or addition of calcium carbonate. Soil solutions were obtained by high speed centrifugation and ultrafiltration (0.2 μm) of samples at 60% water-holding capacity. Concentrations of elements were determined by ICP-ES or (in most elements) ICP-MS, using isotopes specified. Soil solution pH, HCO3 and organic C were also determined.Concentrations of elements in the biomass of A. capillaris were usually inversely related to soil solution pH. The most apparent (p<0.001) inverse, though often curvilinear, relationships between pH and concentrations in shoot biomass were measured for Ag, As, B, Ba, Eu, Ge, Li, Mn, Ni, P and Sr. Positive relationships (p<0.05) were only measured in Ca, Hg, Mg, Mo and S. For concentrations in root biomass, relationships were mostly, but not always, of the same sign and of a similar strength. Though soil solution pH and concentrations of elements were usually quite closely correlated, pH and/or HCO−3 concentration more often accounted for a higher share of the variability in biomass concentration of elements than did soil solution concentration of the same element.

Differences between calcifuge and acidifuge plants in root exudation of low-molecular organic acids

The nature and quantity of low-molecular organic acids (LOAs) exuded by the roots of nine species of calcifuge and nine species of acidifuge wild plants from northern Europe were determined by ion chromatography. Particular attention was paid to differences between the calcifuge and the acidifuge species in the proportions of different LOAs in their root exudates. Great differences in mol% root exudation between the calcifuge and the acidifuge species were found in some acids. The calcifuge species exuded more acetic acid, the acidifuge species more oxalic acid and much more citric acid. In three calcifuge species, however, root exudation of oxalic acid was appreciable, whereas acetic acid exudation was low in these species. The phosphate- and Fe-solubilizing ability of eight LOAs in a rhizosphere limestone soil was also tested. Oxalic acid was the most efficient phosphate solubilizer and citric acid, by far, the most efficient Fe-solubilizer at the concentration (10 mM) tested. It might be hypothesized that acidifuge species use oxalate to solubilize phosphate and citrate to solubilize Fe, in limestone soil. The inability of calcifuge species to grow in limestone soil might, therefore, be due to low root exudation of these acids and, as a result, inability to solubilize phosphate and Fe in limestone soil.

Rare earth elements in forest-floor herbs as related to soil conditions and mineral nutrition

Mixtures of rare earth elements (REEs) in fertilizers are widely used in Chinese agriculture to improve crop nutrition. REE concentrations in wild-growing plants, especially herbs, are little known. This study describes differences in the concentrations and proportions of REEs in eight forest-floor herbaceous plants and relates these differences to soil and mineral nutrient conditions. REEs studied were yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). Leaf concentrations of sum REEs differed more than one order of magnitude between species, being highest in Anemone nemorosa (10.1 nmol/g dry mass) and lowest in Convallaria majalis (0.66 nmol/g) from the same site. Leaf concentrations of all REEs correlated positively (p<0.001), as did sum REE with calcium (Ca) and strontium (Sr) concentrations (p<0.001). A negative relationship (r=−0.83, (p<0.001) was measured between phosphorus (P) concentrations and sum REE concentrations in leaves. However, the proportions of the single REEs in the REE sum differed among species. In A. nemorosa, 57% of the molar REE sum was taken by Y+La, and only 21% by Ce. The other extreme was Maianthemum bifolium, with 37% La+Y and 41% Ce. These two species had 2.7–3.0% of the REE sum as heavier lanthanides, compared to 4.1–5.2% in the six other species. No clear relationship between soil properties or REE contents and leaf REE concentrations was detected. For La, however, an overrepresentation in leaves prevailed throughout all species compared to soils, whereas particularly Nd, Sm, and Tb had a lower proportion in the leaves of all species than in their soils. Possible uptake mechanisms of REEs in plants are discussed.

Testosterone and diurnal rhythmicity of leptin, TNF-alpha and TNF-II receptor in insulin-resistant myotonic dystrophy patients

OBJECTIVE: To investigate the leptin and TNF systems in relation to testosterone in insulin resistant myotonic dystrophy (DM1) subjects.DESIGN AND SUBJECTS: Fasting morning samples and diurnal sampling during 24 h. Forty-two DM1 subjects (20 women and 22 men; age 41.5 (28.5–58.7) y, body mass index (BMI) 23.3 (18.6–29.2) kg/m2; median and 10th and 90th percentile, respectively). Fifty healthy volunteers (23 women and 27 men; age 42 (27.0–56.9) y, BMI 24.0 (20.7–29.7) kg/m2). Nine men with DM1 and nine healthy men participated in diurnal sampling.MEASUREMENTS: Body composition was measured by bioelectric impedance analysis. Circulating levels of leptin, TNF-α, TNFR-II, insulin, testosterone and lipids were measured. The number of CTG triplet repeats was analysed.RESULTS: Basal as well as median 24 h levels of leptin and TNFR-II were significantly increased in DM1 patients, independent of body fat mass. This was associated with higher insulin and lower testosterone levels in DM1 patients. The genetic defect was related to leptin and TNFR-II levels in DM1 patients.CONCLUSION: Hyperleptinemia in DM1 is clearly linked to the concomitant hypogonadism. The genetic defect may directly or indirectly contribute to increased leptin levels. Increased exposure of cytokines may contribute to insulin resistance and other hormonal disturbances in DM1.