Search PubMed⌕ Search

Biomedical subjects

I Persson

Publications and source records attributed to I Persson.

At least 19 recordsLinked to original sources
PubMed2006

Endometriosis and the risk of cancer with special emphasis on ovarian cancer.

BACKGROUND: Several observations of the coexistence of endometriosis and cancer have been published. One study concerning endometriosis patients from 1969 to 1986 showed an overall relative cancer risk of 1.2 and relative risks for breast cancer, ovarian cancer and non-Hodgkin's lymphoma to be 1.3, 1.9 and 1.8, respectively. The aim of this study was to see whether these risk ratios stand in an extended study with longer follow-up. METHODS: Women discharged from a hospital, with a diagnosis of endometriosis from 1969 to 2000, were identified using the National Swedish Inpatient Register. Data were linked to the National Swedish Cancer Register to identify cases of cancer. Data on hysterectomies and oophorectomies were available. Standardized incidence ratios (SIR) were calculated. RESULTS: 64 492 women entered the study. First year of follow-up was excluded, leaving 3349 cases of cancer. There was no increased overall risk of cancer [SIR 1.04, 95% CI 1.00-1.07]. Elevated risks were found for ovarian cancer (SIR 1.43, 95% CI 1.19-1.71), endocrine tumours (SIR 1.36, 95% CI 1.15-1.61), non-Hodgkin's lymphoma (SIR 1.24, 95% CI 1.02-1.49) and brain tumours (SIR 1.22, 95% CI 1.04-1.41). Women with early diagnosed and long-standing endometriosis had a higher risk of ovarian cancer, with SIR of 2.01 and 2.23, respectively. The average age at endometriosis diagnosis was 39.4, indicating that there are the moderate/severe cases that are included in this study. Women who had a hysterectomy before or at the time of the endometriosis diagnosis did not show an increased risk of ovarian cancer. CONCLUSION: Women with endometriosis have an increased risk of some malignancies, particularly ovarian cancer, and the risk increases with early diagnosed or long-standing disease. Hysterectomy may have a preventive effect against ovarian cancer.

Adolescent↗
PubMed2004

Molecular epidemiology of hospital-associated and community-acquired Clostridium difficile infection in a Swedish county.

All episodes of Clostridium difficile associated diarrhea (CDAD) diagnosed in a defined population of 274,000 including one tertiary and two primary hospitals and their catchment areas were studied during 12 months. The annual CDAD incidence in the county was 97 primary episodes per 100,000, and 78% of all episodes were classified as hospital associated with a mean incidence of 5.3 (range, 1.4 to 6.5) primary episodes per 1,000 admissions. The incidence among hospitalized individuals was 1,300-fold higher than that in the community (33,700 versus 25 primary episodes per 100,000 persons per year), reflecting a 37-fold difference in antibiotic consumption (477 versus 13 defined daily doses [DDD]/1,000 persons/day) and other risk factors. Three tertiary hospital wards with the highest incidence (13 to 36 per 1,000) had CDAD patients of high age (median age of 80 years versus 70 years for other wards, P < 0.001), long hospital stay (up to 25 days versus 4 days), or a high antibiotic consumption rate (up to 2,427 versus 421 DDD/1,000 bed days). PCR ribotyping of C. difficile isolates available from 330 of 372 CDAD episodes indicated nosocomial acquisition of the strain in 17 to 27% of hospital-associated cases, depending on the time interval between index and secondary cases allowed (2 months or up to 12 months), and only 10% of recurrences were due to a new strain of C. difficile (apparent reinfection). In other words, most primary and recurring episodes were apparently caused by the patient's endogenous strain rather than by one of hospital origin. Typing also indicated that a majority of C. difficile strains belonged to international serotypes, and the distribution of types was similar within and outside hospitals and in primary and relapsing CDAD. However, type SE17 was an exception, comprising 22% of hospital isolates compared to 6% of community isolates (P = 0.008) and causing many minor clusters and a silent nosocomial outbreak including 36 to 44% of the CDAD episodes in the three high-incidence wards.

Clostridioides difficile↗
PubMed2002

Alcohol, tobacco and breast cancer--collaborative reanalysis of individual data from 53 epidemiological studies, including 58,515 women with breast cancer and 95,067 women without the disease.

Alcohol and tobacco consumption are closely correlated and published results on their association with breast cancer have not always allowed adequately for confounding between these exposures. Over 80% of the relevant information worldwide on alcohol and tobacco consumption and breast cancer were collated, checked and analysed centrally. Analyses included 58,515 women with invasive breast cancer and 95,067 controls from 53 studies. Relative risks of breast cancer were estimated, after stratifying by study, age, parity and, where appropriate, women's age when their first child was born and consumption of alcohol and tobacco. The average consumption of alcohol reported by controls from developed countries was 6.0 g per day, i.e. about half a unit/drink of alcohol per day, and was greater in ever-smokers than never-smokers, (8.4 g per day and 5.0 g per day, respectively). Compared with women who reported drinking no alcohol, the relative risk of breast cancer was 1.32 (1.19-1.45, P<0.00001) for an intake of 35-44 g per day alcohol, and 1.46 (1.33-1.61, P<0.00001) for >/=45 g per day alcohol. The relative risk of breast cancer increased by 7.1% (95% CI 5.5-8.7%; P<0.00001) for each additional 10 g per day intake of alcohol, i.e. for each extra unit or drink of alcohol consumed on a daily basis. This increase was the same in ever-smokers and never-smokers (7.1% per 10 g per day, P<0.00001, in each group). By contrast, the relationship between smoking and breast cancer was substantially confounded by the effect of alcohol. When analyses were restricted to 22 255 women with breast cancer and 40 832 controls who reported drinking no alcohol, smoking was not associated with breast cancer (compared to never-smokers, relative risk for ever-smokers=1.03, 95% CI 0.98-1.07, and for current smokers=0.99, 0.92-1.05). The results for alcohol and for tobacco did not vary substantially across studies, study designs, or according to 15 personal characteristics of the women; nor were the findings materially confounded by any of these factors. If the observed relationship for alcohol is causal, these results suggest that about 4% of the breast cancers in developed countries are attributable to alcohol. In developing countries, where alcohol consumption among controls averaged only 0.4 g per day, alcohol would have a negligible effect on the incidence of breast cancer. In conclusion, smoking has little or no independent effect on the risk of developing breast cancer; the effect of alcohol on breast cancer needs to be interpreted in the context of its beneficial effects, in moderation, on cardiovascular disease and its harmful effects on cirrhosis and cancers of the mouth, larynx, oesophagus and liver.

Adult↗
PubMed2002

Lipids and antioxidative effects of estradiol and sequential norethisterone acetate treatment in a 3-month randomized controlled trial.

OBJECTIVE: To determine the influence of hormone replacement therapy on serum lipids and antioxidative factors associated with the risk of coronary heart disease. METHODS: The effect of a sequential estradiol-norethisterone acetate regimen or placebo on lipid metabolism, antioxidative variables and fatty acid composition in serum was measured during the peak-estrogen phase in a randomized, double-blind, placebo-controlled study of 42 healthy postmenopausal women for 3 months. RESULTS: Active treatment significantly reduced lipoprotein(a) by 15% (p = 0.005, compared with placebo), low-density lipoprotein (LDL) cholesterol by 10% (p = 0.005) and the LDL cholesterol/high-density lipoprotein (HDL) cholesterol ratio by 11% (p = 0.016). Serum triglycerides increased by 21% (p = 0.045). No effect was observed on HDL cholesterol, on apolipoproteins apo A(1) or apo B, or on non-esterified fatty acids in serum. No treatment effect was seen in the proportions of monounsaturated and polyunsaturated fatty acids. The concentration of malondialdehyde in serum did not change with the estrogen-progestin treatment. CONCLUSIONS: This sequential estrogen-progestin therapy has a beneficial effect on apolipoprotein(a) and LDL cholesterol, but no effect on non-esterified fatty acids or the level of lipid peroxidation products in serum.

Administration, Oral↗
PubMed2001

Crystal and solution structures of N,N-dimethylthioformamide-solvated copper(I), silver(I), and gold(I) ions studied by X-ray diffraction, X-ray absorption, and vibrational spectroscopy.

Crystal structures of the solvated copper(I) and silver(I) perchlorate salts crystallizing from N,N-dimethylthioformamide solution have been determined by single-crystal X-ray diffraction at 295 K. Tetrakis(N,N-dimethylthioformamide)copper(I) perchlorate, [Cu(SCHN(CH(3))(2))(4)]ClO(4), crystallizes in the monoclinic space group P2/n (No. 13) with a = 8.428(2), b = 9.605(2), and c = 15.096(3) A, beta = 104.35(2) degrees, and Z = 2. The copper(I) ion in a site of C(2) symmetry coordinates four N,N-dimethylthioformamide ligands in a slightly distorted tetrahedral coordination with Cu-S bond distances of 2.3249(8) and 2.3494(8) A. The triclinic (P1, No. 2) tris(N,N-dimethylthioformamide)silver(I) perchlorate, Ag(SCHN(CH(3))(2))(3)ClO(4), with a = 7.4149(5), b = 7.7953(5), and c = 17.1482(1) A, alpha = 98.341(5), beta = 93.910(5), and gamma = 107.084(5) degrees, and Z = 2, contains centrosymmetric Ag(2)(SCHN(CH(3))(2))(6)(2+) dimers in which two almost planar AgS(3) units are held together by an asymmetric double sulfur bridge with one short and one long Ag-S bond, 2.529(1) and 2.930(1) A, respectively. The Ag-S bond distances to the two terminal N,N-dimethylthioformamide ligands are 2.469(1) and 2.543(1) A. The solvated copper(I) and silver(I) ions in solution were found by means of large-angle X-ray scattering (LAXS) to coordinate four N,N-dimethylthioformamide molecules with the mean Cu-S and Ag-S bond distances 2.36(1) and 2.58(1) A, respectively, probably with distorted tetrahedral coordination geometry, while an EXAFS study gave the Cu-S bond distance 2.34(1) A. EXAFS studies showed a linear S-Au-S entity with an Au-S bond distance of 2.290(5) A in the structure of the solid bis(N,N-dimethylthioformamide)gold(I) tetrafluoroborate, Au(SCHN(CH(3))(2))(2)BF(4). The structure in solution is similar with a mean Au-S bond distance of 2.283(4) A. Raman and infrared vibrational spectra of the solvated copper(I), silver(I), and gold(I) ions in the solid state and N,N-dimethylthioformamide solution have been recorded and assigned.

Absorptiometry, Photon↗
PubMed2001

Structure of the dimethyl sulfoxide solvated thallium(III) ion in solution and in the solid state.

The structure and vibrational spectra of the dimethyl sulfoxide solvated thallium(III) ion have been studied in a dimethyl sulfoxide solution and in the solid state. X-ray crystallography shows a trigonal unit cell, space group R(-)3 (No. 148), for the [Tl(dmso)(6)](ClO(4))(3) compound with Z = 3, a = b = 11.9764(13) [11.8995(9)] A, c = 20.802(2) [20.467(2)] A, and V = 2584.0(5) [2509.9(4)] A(3) at 295 [150] K. The crystal structure comprises a highly symmetric hexakis(dimethyl sulfoxide)thallium(III) ion, with thallium in a (-)3 symmetry site and a Tl-O bond distance of 2.224(3) A at 295 K. The octahedral TlO(6) kernel is compressed along the threefold axis with an O-Tl-O bond angle of 96.20(11) degrees. The Tl-O-S bond angle of 120.7(2) degrees corresponds to a Tl.S distance of 3.292(2) A. One perchlorate ion centered on the (-)3 axis was described by a statistically disordered model. A low-temperature EXAFS study (10 K) resulted in the Tl-O and Tl.S distances of 2.221(4) and 3.282(6) A, respectively, consistent with a Tl-O-S bond angle of 120(1) degrees. The low Debye-Waller factors confirm a regular coordination without the disorder of the dimethyl sulfoxide ligands, which would have resulted from the alternative choice of space group R3 for the crystal structure. Raman and infrared spectra have been recorded and assigned, with the bands at 435 and 447 cm(-)(1) corresponding to the vibrational frequency of the symmetric and asymmetric Tl-O stretching modes, respectively. EXAFS data of a 0.5 mol dm(-3)thallium(III) trifluoromethanesulfonate in a dimethyl sulfoxide solution were consistent with that of a hexasolvated ion with mean Tl-O and Tl.S distances of 2.22(1) and 3.33(2) A, respectively, which correspond to a mean Tl-O-S bond angle of 124(2) degrees. The anomalously large disorder parameter for the Tl-O distances is consistent with a weak pseudo-Jahn-Teller effect. The (205)Tl, (13)C, and (1)H NMR spectra of the complex in solution show single signals at 1886, 39.5, and 2.3 ppm, respectively.

Cations↗
PubMed2001

New class of oligonuclear platinum-thallium compounds with a direct metal-metal bond. 5. Structure determination of heterodimetallic cyano complexes in aqueous solution by EXAFS and vibrational spectroscopy.

The structures of three closely related heterodimetallic cyano complexes, [(NC)(5)Pt-Tl(CN)(n)()](n)()(-) (n = 1-3), formed in reactions between [Pt(II)(CN)(4)](2)(-) and Tl(III) cyano complexes, have been studied in aqueous solution. Multinuclear NMR data ((205)Tl, (195)Pt, and (13)C) were used for identification and quantitative analysis. X-ray absorption spectra were recorded at the Pt and Tl L(III) edges. The EXAFS data show, after developing a model describing the extensive multiple scattering within the linearly coordinated cyano ligands, short Pt-Tl bond distances in the [(NC)(5)Pt-Tl(CN)(n)()](n)()(-) complexes: 2.60(1), 2.62(1), and 2.64(1) A for n = 1-3, respectively. Thus, the Pt-Tl bond distance increases with increasing number of cyano ligands on the thallium atom. In all three complexes the thallium atom and five cyano ligands, with a mean Pt-C distance of 2.00-2.01 A, octahedrally coordinate the platinum atom. In the hydrated [(NC)(5)Pt-Tl(CN)(H(2)O)(4)](-) species the thallium atom coordinates one cyano ligand, probably as a linear Pt-Tl-CN entity with a Tl-C bond distance of 2.13(1) A, and possibly four loosely bound water molecules with a mean Tl-O bond distance of about 2.51 A. In the [(NC)(5)Pt-Tl(CN)(2)](2)(-) species, the thallium atom probably coordinates the cyano ligands trigonally with two Tl-C bond distances at 2.20(2) A, and in [(NC)(5)Pt-Tl(CN)(3)](3)(-) Tl coordinates tetrahedrally with three Tl-C distances at 2.22(2) A. EXAFS data were reevaluated for previously studied mononuclear thallium(III)-cyano complexes in aqueous solution, [Tl(CN)(2)(H(2)O)(4)](+), [Tl(CN)(3)(H(2)O)], and [Tl(CN)(4)](-), and also for the solid K[Tl(CN)(4)] compound. A comparison shows that the Tl-C bond distances are longer in the dinuclear complexes [(NC)(5)Pt-Tl(CN)(n)()](n)()(-) (n = 1-3) for the same coordination number. Relative oxidation states of the metal atoms were estimated from their (195)Pt and (205)Tl chemical shifts, confirming that the [(NC)(5)Pt-Tl(CN)(n)()](n)()(-) complexes can be considered as metastable intermediates in a two-electron-transfer redox reaction from platinum(II) to thallium(III). Vibrational spectra were recorded and force constants from normal-coordinate analyses are used for discussing the delocalized bonding in these species.

Chemical Phenomena↗
PubMed2001

Cigarette smoking, alcohol consumption, and risk of hip fracture in women.

BACKGROUND: Previous studies regarding the impact of cigarette smoking on the risk of hip fracture in postmenopausal women have been inconsistent, suggesting different effects in different groups. The effect of alcohol intake on fracture risk is puzzling: moderate alcohol intake appears to increase bone density, and its association with hip fracture is not clear. METHODS: To assess the associations of cigarette smoking and alcohol consumption with hip fracture risk among postmenopausal women, we conducted an analysis of a population-based case-control study from Sweden. Cases were postmenopausal women, aged 50 to 81 years, who sustained a hip fracture after minor trauma between October 1, 1993, and February 28, 1995; controls were randomly selected from a population-based register during the same period. A mailed questionnaire requesting information on lifestyle habits and medical history was used 3 months after the hip fracture for cases and simultaneously for controls. Age-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were computed by means of logistic regression. RESULTS: Of those eligible, 1328 cases (82.5%) and 3312 controls (81.6%) responded. Compared with never smokers, current smokers had an increased risk of hip fracture (age-adjusted OR, 1.66; 95% CI, 1.41-1.95). Duration of smoking-particularly postmenopausal smoking-was more important than the amount smoked. Former smokers had a small increase in risk (age-adjusted OR, 1.15; 95% CI, 0.97-1.37) that decreased with the duration of cessation. The age-adjusted OR for women consuming alcohol was 0.80 (95% CI, 0.69-0.93). CONCLUSIONS: Cigarette smoking is a risk factor for hip fracture among postmenopausal women; risk decreases after cessation. Alcohol consumption has a weak inverse association with risk.

Age Distribution↗
PubMed2001

Hydration of some large and highly charged metal ions.

EXAFS studies of metal ions with hydration numbers higher than six in aqueous solution, often show asymmetric distribution of the metal-oxygen bond distances. The hydration number can be determined from a correlation with the bond distance. The mean Ca-O distance 2.46(1) A shows the calcium(II) ion to be eight-hydrated in a wide asymmetric distribution. Theoretically calculated EXAFS oscillations for individual snapshots from an MD simulation show large variations. The scandium(III) ion is surrounded by two groups of about eight water molecules, with the mean Sc-O distance 2.185(6) A. The yttrium(III) ion coordinates eight waters in an asymmetric distribution at 2.368(5) A, and the lanthanum(III) ion 6 + 3 water molecules at 2.52(2) and 2.65(3) A, respectively. For the the uranium(IV) and thorium(IV) ions, the M-O distances 2.42(1) and 2.45(1) A, respectively, indicate hydration numbers close to 10.

Cations↗
PubMed2001

Multicomponent polyanions. 57. Large-angle X-ray scattering study of aqueous molybdophenylphosphonate solutions.

The radial distribution functions are calculated from large-angle X-ray scattering (LAXS) measurements for one concentrated aqueous molybdate/heptamolybdate solution and five aqueous molybdophenylphosphonate solutions (lithium chloride medium). Besides water and hydrated lithium, chloride, and molybdate ions, five species in all, having different nuclearities, are postulated to exist in the solutions, according to equilibrium studies using potentiometry and 31P NMR spectroscopy. The structures of the three polymolybdate species Mo7O24(6-), Mo8O26(4-), and (C6H5P)2Mo5O21(4-), for which the structures are determined crystallographically, are confirmed to exist also in aqueous solution. The principal structures of the remaining two complexes, (C6H5P)Mo6O21(OH2)5(2-) and (C6H5P)Mo7O25(OH2)4-, are elucidated with the use of structures of related species. Both anions have one group of four edge-sharing MoO6 octahedra and another group of two MoO6 octahedra connected by sharing corners, forming a bent unsymmetric six-membered ring, with the C6H5PO3 group placed on the crowded side of the ring. In the former, the group of two MoO6 octahedra is edge-shared, while in the latter, the group is face-shared, resulting in a ring small enough to tetrahedrally coordinate to the seventh molybdenum opposite the phenyl group.

Journal Article↗
PubMed2001

Breast cancer risk in relation to amount of tissue removed during breast reduction operations in Sweden.

BACKGROUND: Women who undergo breast reduction operations have substantially lowered risks of breast cancer, and the reasons remain unclear. The current investigation attempted to assess whether the reduction in breast cancer risk was related directly to the amount of breast tissue removed. METHODS: Medical record retrieval was attempted for 161 breast cancer patients in a Swedish cohort of 31,910 women who had had breast reduction surgery and for 483 women who had not developed breast cancer. Information on amount of breast tissue removed was abstracted along with other factors that influence breast cancer risk. Odds ratios of developing breast cancer were calculated based on amount of breast tissue removed. RESULTS: The amount of tissue removed was a significant predictor of risk, as subjects in the highest quartile of tissue removal had a significantly lower risk than those in the lowest quartile. Considering the total amount of tissue removed (both breasts), subjects with > or = 1600 versus < 800 grams removed had an odds ratio (OR) of 0.24 [95% confidence interval (CI) 0.1-0.5]. This relation persisted after adjustment for other breast cancer risk factors and was apparent within every subgroup examined. CONCLUSIONS: The finding that breast cancer risk was reduced in proportion to the amount of tissue removed should be reassuring to women who are considering breast reduction procedures and to women who are electing to have bilateral total prophylactic mastectomies because of a strong genetic predisposition.

Adolescent↗
PubMed2001

Hydration of the calcium ion. An EXAFS, large-angle x-ray scattering, and molecular dynamics simulation study.

The structure of the hydrated calcium(II) ion in aqueous solution has been studied by means of extended X-ray absorption fine structure spectroscopy (EXAFS), large-angle X-ray scattering (LAXS), and molecular dynamics (MD) methods. The EXAFS data displayed a broad and asymmetric distribution of the Ca-O bond distances with the centroid at 2.46(2) A. LAXS studies on four aqueous calcium halide solutions (1.5-2 mol dm(-)(3)) gave a mean Ca-O bond distance of 2.46(1) A. This is consistent with a hydration number of 8 determined from correlations between mean distances and coordination numbers from crystal structures. The LAXS studies showed a second coordination sphere with a mean Ca.O(II) distance of 4.58(5) A, and for the hydrated halide ions the distances Cl.O 3.25(1) A, Br.O 3.36(1) A, and I.O 3.61(1) A were obtained. Molecular dynamics simulations of CaCl(2)(aq) were performed using three different Ca(2+)-OH(2) pair potentials. The potential from the GROMOS program gave results in agreement with experiments, i.e., a coordination number of 8 and an average Ca-O distance of 2.46 A, and was used for further comparisons. Theoretical EXAFS oscillations were computed for individual MD snapshots and showed very large variations, though the simulated average spectrum from 2000 snapshots gave satisfactory agreement with the experimental EXAFS spectra. The effect of thermal motions of the coordinated atoms is inherent in the MD simulation method. Thermal disorder parameters evaluated from simulated spatial atom distribution functions of the oxygen atoms coordinated to the calcium ion were in close agreement with those from the current LAXS and EXAFS analyses. The combined results are consistent with a root-mean-square displacement from the mean Ca-O distance of 0.09(2) A in aqueous solution at 300 K.

Body Water↗
PubMed2001

Metabolic gene polymorphism frequencies in control populations.

Using the International Project on Genetic Susceptibility to Environmental Carcinogens (GSEC) database containing information on over 15,000 control (noncancer) subjects, the allele and genotype frequencies for many of the more commonly studied metabolic genes (CYP1A1, CYP2E1, CYP2D6, GSTM1, GSTT1, NAT2, GSTP, and EPHX) in the human population were determined. Major and significant differences in these frequencies were observed between Caucasians (n = 12,525), Asians (n = 2,136), and Africans and African Americans (n = 996), and some, but much less, heterogeneity was observed within Caucasian populations from different countries. No differences in allele frequencies were seen by age, sex, or type of controls (hospital patients versus population controls). No examples of linkage disequilibrium between the different loci were detected based on comparison of observed and expected frequencies for combinations of specific alleles.

Black People↗
PubMed2000

Estrogens in the causation of breast, endometrial and ovarian cancers - evidence and hypotheses from epidemiological findings.

Estrogens along with progesterone/progestins, and other hormones, are important determinants of cancer in the breast, endometrium and ovary. Estrogens may increase the risk of breast cancer through various mechanisms and at various phases of life, with a possible synergistic effect of progesterone/progestins. Exposure to high doses of placental hormones, such as estrogens and/or progesterone, during pregnancy may play a pivotal role in reducing subsequent breast cancer susceptibility. Estrogens cause endometrial cancer, an effect that can be reduced, prevented or reversed by progesterone/progestin - if allowed to act for a sufficiently long period of each cycle. The role of sex hormones seems important for ovarian carcinogenesis. Intake of combined oral contraceptives has a substantial and well-documented protective effect on endometrial and ovarian cancer risks. Epidemiological observations and experimental data from an animal model indicate that estrogens may have an adverse effect, while progesterone/progestins have a risk reducing effect directly on the ovarian epithelium. Thus, estrogens and other sex hormones have potential effects on the three most important female cancers. Research has yet to define how some of the risk factors can be modified or treatment regimens can be improved to reduce these cancer risks.

Age Factors↗
PubMed2000

Solvation of the bismuth(III) ion by water, dimethyl sulfoxide, N,N'-dimethylpropyleneurea, and N,N-dimethylthioformamide. An EXAFS, large-angle X-ray scattering, and crystallographic structural study.

The structure of the solvated bismuth(III) ion in aqueous, dimethyl sulfoxide, N,N'-dimethylpropyleneurea, and N,N-dimethylthioformamide solution has been studied by means of EXAFS and large-angle X-ray scattering (LAXS). The crystal structures of the solid compounds octakis(dimethyl sulfoxide)bismuth(III) perchlorate, [Bi(OS(CH3)2)8](ClO4)3, hexakis(N,N'-dimethylpropyleneurea)bismuth(III) perchlorate, [Bi(OCN2(CH2)3(CH3)2)6](ClO4)3, and nonaaquabismuth(III) trifluoromethanesulfonate, [Bi(H2O)9](CF3SO3)3 (redetermination), have been determined. The aqueous solutions must be strongly acidic, since the hydrated bismuth(III) ion starts to hydrolyze into Bi6O4(OH)4(6+) complexes already at an excess of strong acid at 1.0 mol.dm-3. For very acidic aqueous perchlorate solutions, the LAXS and EXAFS data gave a satisfactory fit for eight-coordination of the bismuth(III) ion, with a mean Bi-O bond distance of 2.41(1) A. The crystal structure of octakis(dimethyl sulfoxide)bismuth(III) perchlorate shows that the bismuth(III) ion coordinates eight dimethyl sulfoxide molecules via the oxygen atoms in a distorted square antiprismatic configuration. The mean Bi-O bond distance is 2.43 A and the mean Bi...S distance 3.56 A. For the dimethyl sulfoxide solution, the corresponding mean distances were found to be 2.411(6) and 3.535(12) A. The N,N'-dimethylpropyleneurea-solvated bismuth(III) ion is octahedrally coordinated in both solid state and solution with the Bi-O bond distances of 2.324(5) and 2.322(3) A, respectively. The bismuth(III) ion is six-coordinated in the sulfur donor solvent N,N-dimethylthioformamide with a mean Bi-S bond distance of 2.794(8) A. A comparison with the structure of the solvated lanthanum(III) ion shows that the bismuth(III) ion is smaller for all coordination numbers. New effective ionic radii for the bismuth(III) ion in different coordination numbers are proposed, based on results in this study and in the literature.

Bismuth↗
PubMed2000

Steric effects control the structure of the solvated lanthanum(III) ion in aqueous, dimethyl sulfoxide, and N,N'-dimethylpropyleneurea solution. An EXAFS and large-angle X-ray scattering study.

The structure of the solvated lanthanum(III) ion has been determined in aqueous, dimethyl sulfoxide, and N,N'-dimethylpropyleneurea solution by means of the EXAFS and large-angle X-ray scattering (LAXS) techniques. The close agreement between the EXAFS spectra of solid nonaaqualanthanum(III) trifluoromethanesulfonate and of an aqueous lanthanum(III) perchlorate solution shows that the hydrated lanthanum(III) ion in aqueous solution most probably has the same structure as in the solid, i.e., nine water molecules coordinated in a tricapped trigonal prismatic configuration. The data analysis from EXAFS and LAXS measurements of the aqueous solution resulted in the La-O bond distances 2.52(2) and 2.65(3) A to the water molecules in the prism and the capping positions, respectively. The LAXS study shows a second hydration sphere consistent with approximately 18 water molecules at 4.63(2) A. The EXAFS spectra of solid octakis(dimethyl sulfoxide)lanthanum(III) trifluoromethanesulfonate and a dimethyl sulfoxide solution of this salt are also similar. The data analysis of EXAFS and LAXS measurements assuming eight-coordination around lanthanum yielded an La-O bond distance of 2.50(2) A, and an La...S distance of 3.70(3) A, giving an La-O-S angle of 133(2) degrees. The EXAFS data of an N,N'-dimethylpropyleneurea solution of lanthanum(III) trifluoromethanesulfonate gave the La-O bond distance 2.438(4) A and the La...C distance 3.41(2) A, which correspond to an La-O-C angle of 131(2) degrees. The La-O bond distance is consistent with seven-coordination around lanthanum, on the basis of the variation of the ionic radii of the lanthanum(III) ion with different coordination numbers.

Dimethyl Sulfoxide↗
PubMed2000

Astrocyte beta1-adrenergic receptor immunoreactivity and agonist induced increases in [Ca2+]i: differential results indicative of a modified membrane receptor.

Antibodies against the C-terminus of the beta1-adrenergic receptor were used for staining cultured astrocytes from the rat cerebral cortex. Immunoreactivity was found to be localized exclusively to an intracellular organelle structure similar to the Golgi complex, with no staining of the plasma membrane. The astrocytes stained positive with BODIPY CGP 12177, a FITC-conjugated beta-adrenergic receptor agonist, and this staining was blocked by the beta1-adrenergic antagonist atenolol, indicating that these receptors are expressed on the surface of the astrocytes. The presence of functional plasma membrane beta1-adrenergic receptors was further verified using microspectrofluorometry for measurements of intracellular calcium changes upon beta-adrenergic agonist stimulation. Intracellular immunoreactivity confined to the organelles was also found in astrocytes from mixed astroglial-neuronal cultures. In contrast, the neurons in these cultures showed a strong labeling of the cell bodies by the beta1-adrenergic receptor antibodies. Thus, the beta1-adrenergic receptor antibody, which stains the cell bodies of the neurons, recognizes the astroglial receptors only intracellularly, although functional beta1-adrenergic receptors are present on the astroglial surface. Taken together, these data suggest that the beta1-adrenergic receptors observed intracellularly might be processed on their passage to the surface to a modified form of the final plasma membrane receptor, which is not recognized by the antibodies.

Adrenergic alpha-Agonists↗