PubMed Health⌕ Search

Biomedical subjects

T Lövgren

Publications and source records attributed to T Lövgren.

At least 109 records · Page 6Linked to original sources
PubMed1979

Simultaneous solubilization of steroid hormones II: androgens and estrogens.

The simultaneous solubilization of some androgens and estrogens in aqueous polysorbate 40, tetradecyltrimethylammonium bromide, and sodium lauryl sulfate was studied. The solubilizations of estradiol and testosterone were independent of each other in all three association colloids. However, if the estrogen component was ethinyl estradiol, the solubilization was dependent on the addition order. The estrogen precipitates more readily than testosterone in polysorbate 40 and tetradecyltrimethylammonium bromide, but the opposite is true in sodium lauryl sulfate. The simultaneous solubilizations of methyltestosterone or ethisterone with the estrogens tested were different from those of testosterone. The solubilization behavior of the steroids is discussed, starting with the pseudophase model and different solubilization loci. Results indicated that the free energy change of micellar binding, delta Gb, decreases with increased steroid polarity. The simultaneous solubilization cannot be predicted by delta Gb but may be explained by differences in the solubilization mechanism.

Androgens↗
PubMed1979

Uterine and ovarian estrogen receptor levels in climacteric women.

High affinity cytoplasmic estrogen receptors in the endometrium, myometrium and ovary of 15 climacteric women were studied. In addition, the concurrent serum estradiol and progesterone level of each woman was estimated and the endometrium examined histologically. The cytoplasmic estrogen receptor level of the endometrium and myometrium had remained extremely high in some cases several years after the menopause and in the presence of a completely atrophied endometrium. The lowest endometrial and myometrial estrogen receptor levels in pre-menopausal women were measured towards the end of the menstrual cycle. The eodometrial estrogen receptor level was roughly 2--3 times the comparable myometrial level. Estrogen receptors were also encountered in all cases in the cervical myometrium. The estrogen receptor levels of the ovary were low in all cases.

Adult↗
PubMed1978

Simultaneous solubilization of steroid hormones I: estrogens and C21 steroids.

The simultaneous solubilization of some estrogens and C21 steroids in aqueous polysorbate 40, tetradecyltrimethylammonium bromide, and sodium lauryl sulfate was studied. The less soluble estrogen estradiol was solubilized independently of the C21 steroids. The micellar solubilities of ethinyl estradiol and both corticosterone and hydrocortisone were independnet of the presence of each other while the solubility of 11alpha-hydroxyprogesterone was enhanced by ethinyl estradiol. The solubilizations of ethinyl estradiol and the two C21 steroids, progesterone and 21-hydroxyprogesterone, were dependent on each other so that a varying amount of the steroid solubilized first was precipitated by an excess of the second steroid. If saturated solutions of the two steroids were mixed, no precipitation occurred. A possible mechanism for the simultaneous solubilization of steroids and its relation to structure are discussed.

Chemistry, Pharmaceutical↗
PubMed1978

In vitro sensitivity of Trichomonas vaginalis and Candida albicans to chemotherapeutic agents.

Strains of fresh clinical isolates of Trichomonas vaginalis and Candida albicans have been tested in vitro for their sensitivity to eight drugs used in the therapy of monilial and trichomonal vaginitis. Three of the chemotherapeutic agents, chlorchinaldol, clotrimazole and broxyquinoline were effective against both organisms. Tinidazole and metronidazole were active against T. vaginalis. The strains of C. albicans were also sensitive to trichomycin, natamycin and nystatin. Tinidazole was the most effective trichomonacide, clotrimazole and chlorchinaldol were most effective against C. albicans, while chlorchinaldol had the best in vitro effect against both organisms. The ranges of the MICs are compared to values previously reported.

Antifungal Agents↗
PubMed1978

On the properties of alpha-glucosidase and the binding of glucose to the enzyme.

An alpha-glucosidase was purified from baker's yeast. The molecular weight was approximately 44 000 daltons. SDS-disc gel electrophoresis suggested that the enzyme consisted of four subunits. The isoelectric point was at pH 5.4. The Km values for p-nitrophenyl alpha-D-glucopyranoside and maltose were 2.9 X 10(-4) and 2.5 X 10(-2) M, respectively. Binding of 2-(p-toluidino)naphthalene-6-sulfonate to the alpha-glucosidase was associated with a strong increase in fluorescence. The dissociation constant of the enzyme-TNS complex was 8 X 10(-5) M. The fluorescent probe did not interfere with the binding of glucose to the enzyme although the alpha-glucosidase was inhibited by high concentrations of TNS. The formation of an enzyme-glucose complex was indicated by an increase of fluorescence and by a shift in the wavelength for maximal emission which suggests that the binding process is associated with a change in conformation. The dissociation constant of the glucose--alpha-glucosidase complex KD = 0.57 X 10(-3) M, was calculated from the increase in fluorescence as a function of glucose concentration.

Glucose↗
PubMedDate not supplied

Zeptomole detection sensitivity of prostate-specific antigen in a rapid microtitre plate assay using time-resolved fluorescence.

Prostate-specific antigen (PSA) was detected in microtitre wells coated with a PSA-specific antibody using biotinylated antibody and streptavidin-coated, highly fluorescent 107 nm nanoparticles, which contained more than 30000 europium ions entrapped by beta-diketones. PSA was monitored directly on the surface of a well without any additional enhancement step. The sensitivity of the assay was 1.6 ng/L, corresponding to 50 fmol/L or 250 zeptomoles (250 x 10(-21) mol/L) of PSA. The high specific activity and low non-specific binding of the streptavidin-coated nanoparticles improved the sensitivity of the PSA assay 100-fold compared to the conventional europium-labelled streptavidin tracer in the same assay format. Additionally, the streptavidin-coated nanoparticle label made very rapid assays possible, due to the high affinity of the streptavidin-biotin complex and a high number of binding sites available for tracing the biotinylated antibody on the surface. Due to the inherent problems of tracing analyte with a complex of biotinylated antibody and streptavidin-coated nanoparticles, the streptavidin-coated nanoparticles reacting with the surface-captured analyte and biotinylated antibody was favoured and factors influencing this are discussed. This universal labelling technology can be applied to detect any biotinylated molecule, either in solution or on a solid phase, in order to improve detection sensitivities in many areas of biochemical analysis, such as cyto- and histochemistry, multianalyte DNA-chip assays and single-particle assays.

Antibodies, Monoclonal↗
PubMedDate not supplied

Demonstration of estrogen receptors in the skin.

The occurence of high affinity and limited capacity estrogen receptors in skin specimens was investigated and the concentrations of cytoplasmic and nuclear receptors were studied in 14 normal and 22 castrated women. The skin estrogen receptor levels were low in all cases examined, although they usually exceeded the limit value used for estrogen receptor levels in breast cancer tissue. The cytoplasmic and nuclear receptor concentrations in normal women varied from 2.4 to 9.0 and from 1.5 to 7.0 fmol/mg cytosol protein, respectively. The receptor was present as a very high affinity binding component (KD = 0.2- 1.6 x 10(-9)M). The estrogen receptor concentrations in the skin during estriol succinate and estriol valerate therapy were at roughly the same level as during the normal menstrual cycle. The patients who received no replacement therapy after castration displayed the lowest skin estrogen receptor levels. The share of nuclear receptors seemed to be smaller on average during the normal menstrual cycle and in castrated patients not given estrogen therapy than in women treated with estriol succinate or estradiol valerate.

Adult↗
PubMedDate not supplied

Structural analysis of an anti-estradiol antibody.

An anti-estradiol antibody with improved specificity is searched for by combining steroid analog binding studies, mutant antibodies obtained from a phage-display library and structural modeling. Three-dimensional models for the anti-estradiol antibody 57-2 were constructed by comparative model building. Estradiol and analogs were docked into the combining site and molecular dynamics simulation was used to further refine this area of the protein. Cross-reactivities measured against 36 steroid analogs were used to help in the docking process and to evaluate the models. The roles of a number of residues were assessed by characterization of cross-reactivity mutants obtained from a phage display library. The cross-reactivity data and the results observed for mutants are explained by the structural model, in which the estradiol D-ring inserts deeply into the binding site and interacts with the antibody through at least one specific hydrogen bond. The binding data strongly suggest that this hydrogen bond connects the estradiol 17-hydroxyl group with the side chain of Gln H35. As expected for the binding of a small aromatic molecule, the antibody binding site contains many aromatic residues, e.g. Trp H50, H95 and L96 and Tyr L32, L49 and Phe L91.

Amino Acid Sequence↗
PubMedDate not supplied

Europium-labeled oligonucleotide hybridization probes: preparation and properties.

A chemical method for labeling of oligonucleotide probes with europium chelates is presented. A modified deoxycytidine phosphoramidite is used to introduce multiple reactive amino groups to the oligonucleotide during the synthesis phase. Upon deprotection and purification of the modified oligonucleotide, an isothiocyanate derivative of a stable Eu chelate is reacted with the primary amino groups. The labeling technology enables the coupling of a high number of Eu chelates to a single probe. The melting temperatures and hybridization efficiencies of the oligonucleotides are not significantly altered by the labeling process. However, hybridization kinetics of the oligonucleotides are affected by the introduction of multiple modified deoxycytidine residues. In a solid-phase hybridization assay up to 10(7) target molecules can be detected.

Base Sequence↗