OBJECTIVETo investigate the progesterone-binding site on the normal fertile human sperm membrane after 2 hours of in vitro capacitation.

METHODSViable spermatozoa were selected by a swim-up method. After 2 hours of in vitro capacitation, multipoint saturation binding experiments were performed. Sperm suspension and increasing concentrations of progesterone-11alpha-glucuronide-[125I] iodotyramine (125I-P) were added to 7 total binding tubes respectively, and equal amounts of sperm suspension and 125I-P were added to another 7 corresponding non-specific binding tubes in the presence of 10 micromol/L progesterone. After incubation for 1 hour at 4 degrees C, the radioactivity of both the tubes and the pellets after centrifugation was measured respectively. The equilibrium dissociation constant (Kd) and maximum binding capacity (Bmax) were calculated using the mathematical model of single site multi-point saturation method of Scatchard function and least-squares regression.

RESULTSKd was (0.61 +/- 0.04) nmol/L and Bmax was (830 +/- 344) sites/cell. The significance test of the regression equation indicated that r = -0.980, P < 0.01.

CONCLUSIONThere is a high affinity and low capacity binding site for the progesterone (progesterone receptor) on the normal fertile human sperm membrane.

Adult ; Cell Membrane ; chemistry ; Humans ; Male ; Progesterone ; Radioligand Assay ; Receptors, Progesterone ; analysis ; Sperm Capacitation ; Spermatozoa ; chemistry

OBJECTIVE: Oxytocin antagonists maybe useful in inhibiting the uterine contractions of preterm labor. One such compound is TT-235. The purpose of this study was to compare the resistance of TT-235 and oxytocin to enzymatic degradation by oxytocinase in pregnant human. METHODS: Blood samples from pregnant women not in labor were incubated in vitro with known amounts of oxytocin and TT-235. Samples were collected at 0, 15, 30, 45 and 60 minute intervals for oxytocin analysis and at 0, 10, 60 and 360 minutes for TT-235 analysis. Oxytocin was analyzed by radioimmunoassay after extraction while TT-235 was analyzed by radioreceptor assay. RESULTS: In human blood, oxytocin was readily metabolized with greater than 83% disappearance over the 60 minute incubation period. In contrast, TT-235 was stable up to 360 minutes of incubation. CONCLUSION: This study suggests that: (1) blood from pregnant human does contain oxytocinase at least in vitro; and (2) TT-235 was resistant to enzymatic degradation by human blood, implying that this oxytocin antagonist may have prolonged activity in vivo in humans.
Cystinyl Aminopeptidase ; Female ; Humans ; Metabolism* ; Obstetric Labor, Premature ; Oxytocin* ; Plasma* ; Pregnancy ; Pregnant Women* ; Radioimmunoassay ; Radioligand Assay ; Uterine Contraction ; Uterus

To explore novel antifatigue agents targeting with AMPA receptor, 10 compounds were synthesized and their structures were confirmed by 1H NMR, ESI-MS and elemental analysis. 1-BCP was treated as the leading compound. The antifatigue activities were evaluated by weight-loaded forced swimming test, and the AMPA receptor binding affinities were tested with radioligand receptor binding assays. The results unveiled that 5b appeared to possess potent antifatigue activities and high affinity with AMPA receptor, which deserved further studies.
Animals ; Benzamides ; chemistry ; pharmacology ; Dioxoles ; chemistry ; pharmacology ; Fatigue ; prevention & control ; Piperidines ; chemistry ; pharmacology ; Radioligand Assay ; Receptors, AMPA ; metabolism ; Swimming

Background: A lifelong thyroxine therapy is indicated in all patients who have hypothyroidism as a result of autoimmune thyroiditis. However, it has been reported that some hypothyroid patients with autoimmune thyroiditis have spontaneous remission with restriction of iodine intake instead of thyroxine therapy. The purpose of study was to investigate how many hypothyroid patients with autoimmune thyroiditis can recover from hypothyroidism with restriction of iodine intake instead of thyroxine therapy and which factors predict recovery from hypothyroidism. Methods: We studied 64 patients with autoimmune thyroiditis(goitrous autoimmune thyroiditis 56, atrophic autoimmune thyroiditis 8). Thyroxine therapy was discontinued in patients with goitrous autoimmune thyroiditis on the way(group 1, n=32) or from the beginning(group 2, n=24) and atrophic autoimmune thyroiditis on the way(group 3, n-8). All patients were asked to avoid iodine-rich foods and thyroid function was monitored every one to two months for up to 35 months. Serum T3, T4, TSH concentrations, antithyroglobulin and antimicrosomal antibodies were measured by radioimmunoassay(RIA). TSH binding inhibitor immunoglobulin(TBII) was measured in serum using radioreceptor assay. Two hundred micrograms of thyrotropin releasing hormone (TRH) were given as intravenous bolus and TSH levels were measured in blood samples taken at 0, 30, and 60 minutes. All values were expressed as mean+-SEM. Statistical analysis was done with paired or non-paired t-test, ANOVA, and the Chi-square test. Statistical significance was defined as p-value below 0.05. Results: Thirteen(40.6%) of 32 patients in group 1 remained euthyroid after 12-35 months of discontinuation of thyroxine therapy. The other 19(59.4%) patients in group 1 had recurrences of hypothyroidism within 3 months after discontinuation of thyroxine therapy. In 11(45.8%) out of 24 patients in group 2, serum TSH concentrations declined below 5 mU/L within 3 months without thyroxine therapy. The other 13(54.2%) patients in group 2 remained hypothyroid till 2-16 months and the thyroxine was given. In contrast, all 8 patients in group 3 had recurrences of hypothy- roidism within 3 months after stopping thyroxine therapy. When we compared the recovered patients of goitrous autoimmune thyroiditis with the non-recovered patients of goitrous autoimmune thyroiditis, regardless of thyroxine therapy from the beginning, age at onset of disease of the 24 recovered patients was significantly younger than the 32 non-recovered patients(30.1+2.0 years vs. 40.2+ 2.4 years; p=0.004). Concl#usion: These findings suggest that 42.9% of hypothyroid patients with goitrous autoim- mune thyroiditis remain or become spontaneously euthyroid with restriction of iodine intake instead of thyroxine therapy. Young age may be a predicting factor of recovery from hypothyroidism in goitrous autoimmune thyroiditis.
Age of Onset ; Antibodies ; Humans ; Hypothyroidism ; Iodine ; Radioligand Assay ; Recurrence ; Remission, Spontaneous ; Thyroid Gland ; Thyroiditis ; Thyroiditis, Autoimmune ; Thyrotropin-Releasing Hormone ; Thyroxine

OBJECTIVETo establish a protocol of automated synthesis of 1-(2-chlorophenyl)-N-[(11)C]methyl-N-(1-methylpropyl)-3-isoquinoline carboxamide ((11)C-PK11195) as the positron-emitter-labeled ligand for peripheral benzodiazepine receptor (PBR) using a commercial synthesizer and explore the quality control methods for the resulting product.

METHODS(11)C-methyl iodide ((11)C-CH(3)I) was synthesized via liquid-phase distillation approach using a (11)C-iodomethane synthesizer. (11)C-PK11195 was prepared by (11)C-methylation of 1-(2-chlorophenyl)-N-(1-methylpropyl)-3-isoquinoline carboxamide (N-demethyl-PK 11195) as the precursor with (11)C-CH(3)I and purified by semi-preparative reversed phase high performance liquid chromatography (HPLC). The radiochemical purity, chemical purity and stability of the product were evaluated by HPLC, and the toxicity was assessed in normal mice. The factors that affected (11)C-PK11195 synthesis were also studied.

RESULTS(11)C-PK11195 was successfully synthesized using the TracerLab FX(F-N) synthesizer. The synthesis time was about 35 min from the end of (11)C-carbon dioxide production by cyclotron to the end of (11)C-PK11195 synthesis (EOS), with a (11)C-methylation reaction time of 3-4 min. The uncorrected radiochemical yield for (11)C-methylation was (33-/+5)%. Analysis with radio-analytical HPLC showed a radiochemical purity and chemical purity of the product both exceeding 99%, with a specific radioactivity of 30-65 GBq/micromol at EOS (from the end of radionuclide production). The (11)C-PK11195 synthesized was radiochemically stable at room temperature and showed low toxicity in normal mice.

CONCLUSIONThe (11)C-PK11195 injection can be conveniently prepared using an automated synthesizer for clinical use in positron emission tomography.

Animals ; Carbon Radioisotopes ; Contrast Media ; chemical synthesis ; Isoquinolines ; adverse effects ; chemical synthesis ; Mice ; Positron-Emission Tomography ; Radioligand Assay ; Radiopharmaceuticals ; adverse effects ; chemical synthesis ; Receptors, GABA-A ; metabolism

Radioiodinated oxytocin prepared by the lactoperoxidase method exhibited a substantial biologic activity in uterotonic assay of the rat uterus. 125I-oxytocin was bound to the uterine membrane particulate fraction, but the unlabelled oxytocin did not inhibit the binding of 125I oxytocin to the membrane fraction of rat uterus. Cold iodinated oxytocin, however, inhibited the 125I-oxytocin binding to the membrane fraction of rat uterus in proportion to its concentration. These results suggest that 125I-oxytocin is not a suitable radioligand for oxytocin receptor binding study.
Animal ; Binding Sites ; Cell Membrane/metabolism ; Female ; Iodine Radioisotopes/metabolism* ; Oxytocin/metabolism* ; Radioligand Assay ; Rats ; Receptors, Cell Surface/analysis* ; Uterus/metabolism*

OBJECTIVETo investigate the binding characteristics of endothelial cell (EC) with LPS free from the participation of serum factors.

METHODSLaser confocal microscope was employed in the observation of the binding of EC with FITC-LPS. The KD and the binding sites of each EC were calculated by radioligand binding assay of receptors (RBA) using [(3)H]-LPS.

RESULTSThe binding of EC with LPS was saturable, time and concentration dependent and it could be competed with overdosed LPS of the same type. The fluorescence mainly distributed in cytoplasm, especially near the nucleus, which could also be stained.

CONCLUSIONSThere might be some specific LPS binding sites existing on ECs and LPS could function intracellularily.

Cells, Cultured ; Dose-Response Relationship, Drug ; Endothelial Cells ; drug effects ; metabolism ; Fluorescein-5-isothiocyanate ; Fluorescent Dyes ; Humans ; Lipopolysaccharides ; metabolism ; Microscopy, Confocal ; Radioligand Assay ; Umbilical Veins ; cytology

Background: Graves disease is an autoimmune disease caused by TSH receptor antibodies. Thyrotropin binding inhibitor immunoglobulins(TBII) are detected in most Graves patients, but some patients have no TBII activities in their sera. It is unknown whether the clinical features of TBII-positive patients are different from those of TBII-negative patients. Methods: To evaluate the prevalence of TBII-negative Graves' patients and its clinical differences from TBII-positive patients, we examined TBII by radioreceptor assay in 686 consecutive untreated Graves patients. We found 84 TBII-negative patients(15 men and 69 women, mean age ±EM: 40.9±.4 years) and compared their clinical characteristics with 87 TBII-positive patients (22 men and 65 women, mean age±EM: 39.9±.5 years) who were selected randomly from the same patients group. Results: In this study, TBII was undetectable in 12.2% of patients with Graves' disease(84 of 686). TBII-negative group had a less weight loss than TBII-positive group. However, there was no significant differences in age, sex ratio, prevalence of ophthalmopathy, duration of illness and positive rate of family history for thyroid diseases between TBII-negative and
Antibodies ; Autoantibodies ; Autoimmune Diseases ; Female ; Graves Disease ; Humans ; Male ; Prevalence ; Radioligand Assay ; Receptors, Thyrotropin ; Sex Ratio ; Sodium Pertechnetate Tc 99m ; Thyroid Diseases ; Thyroid Gland ; Thyrotropin ; Weight Loss

OBJECTIVETo study age-dependent changes in beta-adrenergic responsiveness and their possible mechanisms.

METHODSResponsiveness to the beta-adrenergic agonists isoprenaline, BRL37344, forskolin, and dibutyryl cyclic AMP (DBcAMP) was examined in samples from 10 older patients by using a cellular function test. A radioligand binding assay was performed using the non-selective beta-adrenergic receptor ligand [3H]-dihydroalprenolol ([3H]-DHA). Specimens from 10 young men were used as controls.

RESULTSThere were no age-dependent changes in contractile response to KCl. The relaxation responses to isoprenaline, BRL37344, and forskolin decreased in the aged group by 15.0%, 17.6%, and 12.6%, respectively (P < 0.001). The pD2 values for isoprenaline and BRL37344 also declined significantly. There was no difference in the responsiveness to dibutyryl cyclic AMP (DBcAMP) between the two groups; the maximum binding site decreased significantly with increasing age, but the equilibrium-dissociation constant did not change.

CONCLUSIONSThere is an age-related decline in beta-adrenergic responsiveness which might be one of the causative factors of reduced bladder compliance in the elderly. A decrease in cAMP level caused by reduced receptor density and adenylyl cyclase activity might be the underlying molecular mechanism of the changes in beta-adrenergic responsiveness.

Adrenergic beta-Agonists ; pharmacology ; Age Factors ; Aged ; Aging ; physiology ; Female ; Humans ; Male ; Middle Aged ; Muscle Contraction ; physiology ; Muscle, Smooth ; physiology ; Radioligand Assay ; Receptors, Adrenergic, beta ; physiology ; Urinary Bladder ; physiology

OBJECTIVETo study the acute effects of dimethoate on the muscarinic-receptors(M1, M2) in the brain of rats.

METHODS24 Sprague-Dawley rats were divided into 4 groups randomly. They were administered subcutaneously with 0, 25, 50, 100 mg/kg dimethoate, respectively. Brains were removed after 48 hours of administration. Radioligand binding assay was used to determine the density and affinity of M1 and M2 receptors.

RESULTSRats in the treated group showed low density of M1 and M2 receptors compared with the control rats. The brain M1 receptor density of the rats in the highest dosage group was significantly lower than that in the control group while brain M2 receptors density had a decrease trend with increasing dosage, but the difference showed no significance. However, there were no differences of the affinity of both M1 and M2 among different treated groups. Correlation analysis showed there is positive relationship between cholinesterase activity and density of M1 receptors(r = 0.583, P < 0.01).

CONCLUSIONM1 and M2 receptors density decreased with the increasing dosage of dimethoate. It is suggested that the alleviating of cholinergic symptoms may be due to the decrease of M1 and M2 receptors in rat brain.

Animals ; Brain ; drug effects ; metabolism ; Cholinesterases ; metabolism ; Dimethoate ; pharmacology ; Dose-Response Relationship, Drug ; Radioligand Assay ; Rats ; Rats, Sprague-Dawley ; Receptor, Muscarinic M1 ; analysis ; drug effects ; Receptor, Muscarinic M2 ; analysis ; drug effects