Implications of nipple discharge in Hong Kong Chinese women.

INTRODUCTION: There are no recent data on nipple discharge and its association with malignancy in Hong Kong Chinese women. This study reported our 5-year experience in the management of patients with nipple discharge, and our experience of mammography, ultrasonography, ductography, and nipple discharge cytology in an attempt to determine their role in the management of nipple discharge. METHODS: Women who attended our Breast Clinic in a university-affiliated hospital in Hong Kong were identified by retrospective review of clinical data from January 2007 to December 2011. They were divided into benign and malignant subgroups. Background clinical variables and investigative results were compared between the two subgroups. We also reported the sensitivity, specificity, and positive and negative predictive values of the investigations that included mammography, ultrasonography, ductography, and cytology. RESULTS: We identified 71 and 31 patients in the benign and malignant subgroups, respectively. The median age at presentation for the benign subgroup was younger than that of the malignant subgroup (48 vs 59 years; P=0.003). A higher proportion of patients in the malignant subgroup than the benign subgroup presented with blood-stained nipple discharge (87.1% vs 47.9%; P=0.002). Mammography had a specificity of 98.4% and positive predictive value of 66.7%; ultrasonography had a specificity of 87.0% and negative predictive value of 75.0%. Cytology and ductography were sensitive but lacked specificity. Ductography had a negative predictive value of 100% but a low positive predictive value (14.0%). Clinical variables including age at presentation, duration of discharge, colour of discharge, presence of an associated breast mass, and abnormal sonographic findings were important in suggesting the underlying pathology of nipple discharge. Multiple logistic regression showed that blood-stained discharge and an associated breast mass were statistically significantly more common in the malignant subgroup. CONCLUSIONS: In patients with non-blood-stained nipple discharge, a negative clinical breast examination combined with negative imaging could reasonably infer a benign underlying pathology.

Novel lead generation through hypothetical pharmacophore three-dimensional database searching: discovery of isoflavonoids as nonsteroidal inhibitors of rat 5 alpha-reductase.

A hypothetical pharmacophore of 5 alpha-reductase inhibitors was generated and served as a template in virtual screening. When the pharmacophore was used, eight isoflavone derivatives were characterized as novel potential nonsteroidal inhibitors of rat 5 alpha-reductase. This investigation has demonstrated a practical approach toward the development of lead compounds through a hypothetic pharmacophore via three-dimensional database searching.

Effect of hydroxyzine on the transport of etoposide in rat small intestine.

Etoposide, an anti-neoplastic agent and a substrate of P-glycoprotein (P-gp), exhibits variable oral bioavailability. P-gp, the multidrug resistance gene (mdr1) product, has been considered as an absorption barrier against intestinal drug absorption. Terfenadine, an antihistamine, has been shown to be a P-gp inhibitor. The current study was designed to assess the effect of hydroxyzine, an antihistamine, on the transport of etoposide in the small intestine. Everted rat gut sacs were used to determine the absorption and exsorption of etoposide under different conditions, as rhodamine 123 was chosen to evaluate the role of P-gp in the drug interaction. The results showed that the transport of etoposide was significantly increased from the luminal site to the serosal site in the jejunum by 2- and 4-fold after 90 min in the presence of hydroxyzine and quinidine, respectively. A similar trend was observed in the ileal sacs. This in vitro exsorption study also demonstrated that hydroxyzine could reduce the efflux of etoposide to the luminal site in either jejunum or ileum. The effect of hydroxyzine on the pharmacokinetics of etoposide differed by the in vivo route of administration, thus assuming clinical importance for chemotherapeutic treatment.

Perturbation of platelet adhesion to endothelial cells by plasminogen activation in vitro.

To investigate whether the endothelium-platelet interactions may be altered by plasminogen activation, cultured human umbilical vein endothelial cells (ECs) were treated with tissue-type plasminogen activator (t-PA) in the presence of plasminogen, and platelet adhesion to ECs was subsequently measured by using a tapered flow chamber. Our results demonstrated that platelets adhered more readily to t-PA treated EC monolayer than to the control monolayer at all shear stress levels tested. This phenomenon was treatment time-dependent and dose-dependent, and it could be blocked by adding plasmin inhibitors, such as epsilon-amino caproic acid and aprotinin. Adherent platelets on t-PA treated EC monolayer underwent more severe shape change than those on the control monolayer. While the extracellular matrix directly treated with t-PA attracted less platelets than the control matrix did, platelet adhesion to the matrix that was produced by t-PA-treated ECs was unaltered. These data suggest that t-PA treatment on ECs compromised antiplatelet-adhesion capability on their apical surface without altering the reactivity of their extracellular matrix towards platelets.

Site-directed mutagenesis of cysteinyl and serine residues of human thromboxane A2 receptor in insect cells.

A thromboxane A2 receptor cDNA was isolated from a human placenta library by polymerase chain reaction (PCR) and was expressed in insect (Sf21) cells using baculovirus system. The recombinant receptor exhibited [3H]-SQ29548 and [125I]-BOP binding activities with Kd values of 1.01 +/- 0.09 nM and 1.63 +/- 0.23 nM, respectively. The receptor binding activity was inhibited by dithiothreitol in a time- and concentration-dependent manner, indicating the involvement of disulfide linkage in ligand binding. The role of the four conserved cysteinyl residues in ligand binding was further examined by site-directed mutagenesis. Each of the four cysteinyl residues was respectively mutated to a serine residue. C102S, C105S, and C183S mutants exhibited no ligand binding activity although successful expression was achieved as revealed by immunoblot analysis, whereas C257S mutant retained most of the binding activity. Homology analysis of all prostanoid receptors indicates that Cys-105 (first extracellular loop) and Cys-183 (second extracellular loop) are conserved and are presumed to form a disulfide bond for receptor stability as suggested by the inhibition of ligand binding by dithiothreitol reduction. Loss of binding activity by C102S mutant revealed that the sulfhydryl group of Cys-102 must play an essential role in ligand binding. Molecular modeling proposed that the Ser-201 is involved in interacting with TXA2 by forming hydrogen bonding. Point mutations of both Ser-201 and a conserved Ser-255 did not affect the ligand binding specificity and affinity for [3H]-SQ29548, but have significantly altered Kd values for [125I]-BOP. These results indicate that various cysteinyl and serine residues of thromboxane A2 receptor may play different roles in ligand binding.

TXA2 agonists inhibit high-voltage-activated calcium channels in rat hippocampal CA1 neurons.

Whole cell voltage clamp recordings were used to investigate the effects of thromboxane A2 (TXA2) agonists on the voltage-dependent Ca2+ currents in rat hippocampal CA1 neurons. TXA2 agonists [1S-[1 alpha, 2 beta(5Z), 3 alpha(1E, 3S*)4 alpha ]]-7-[3-[3-hydroxy-4-(4'-iodophenoxy)-1-butenyl]-7-oxabicyclo [2,2,1]heptan-2-yl]-5-heptenoic acid (I-BOP) and U-46619, reversibly suppressed the whole cell Ca2+ currents in a concentration-dependent manner. The effect was blocked by specific TXA2 receptor antagonist, SQ-29548. I-BOP as well as U-46619 inhibited both omega-conotoxin GVIA (CgTx)-sensitive and nimodipine sensitive Ca2+ currents but had no effect on CgTx/nimodipine insensitive Ca2+ currents. The I-BOP and U-46619 inhibition of Ca2+ currents was blocked by internal dialysis of hippocampal neurons with specific protein kinase C (PKC) inhibitors, NPC-15437 and PKC inhibitor-(19-36). Pretreatment of hippocampal neurons with either 5 micrograms/ml pertussis toxin (PTX) or 5 micrograms/ml cholera toxin (CTX) did not significantly affect the suppression of the Ca2+ currents by I-BOP and U-46619. Dialyzing with 1 mM guanosine 5'-O-(3-thiotriphosphate) or 1 mM GDP significantly attenuated the I-BOP or U-46619 action. These results demonstrate that TXA2 agonists inhibit both CgTx- and nimodipine-sensitive Ca2+ currents but not CgTx/nimodipine-insensitive currents in rat hippocampal CA1 neurons via a PTX- and CTX-insensitive G protein-coupled activation of the PKC pathway.

Thromboxane A2 agonist modulation of excitatory synaptic transmission in the rat hippocampal slice.

1. The effects of the selective thromboxane A2 (TXA2) receptor agonist I-BOP on neuronal excitability and synaptic transmission were studied in the CAl neurones of rat hippocampal slices by an intracellular recording technique. 2. Superfusion of I-BOP (0.5 microM) resulted in a biphasic change of the excitatory postsynaptic potential (e.p.s.p.), which was blocked by pretreatment with SQ 29548, a specific antagonist of TXA2 receptors. The inhibitory phase of I-BOP on the e.p.s.p. was accompanied by a decrease in neuronal membrane input resistance. 3. The sensitivity of postsynaptic neurones to glutamate receptor agonists, alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) or N-methyl-D-aspartate (NMDA), was unchanged by I-BOP (0.5 microM) pretreatment. 4. Bath application of Ba2+ (0.5 mM) prevented both the I-BOP-induced reduction of the neuronal membrane input resistance and the blockade of e.p.s.p. induced by I-BOP. 5. Intracellular dialysis of the hippocampal CA1 neurones with GDP (10 mM) significantly attenuated the I-BOP inhibition of e.p.s.p. and membrane input resistance. Incubation of the slices with either pertussis toxin (PTX, 5 micrograms ml-1 for 12 h) or cholera toxin (CTX, 5 micrograms ml-1 for 12 h) did not affect the biphasic action of I-BOP on the e.p.s.p. or the reduction of membrane input resistance induced by I-BOP. 6. Pretreatment of the slices with the protein kinase C (PKC) inhibitor, NPC-15437 (20 microM), abolished the biphasic modulation by I-BOP (0.5 microM) of the e.p.s.p. Intracellular application of a specific PKC inhibitor, PKCI 19-36 (20 microM), completely inhibited the I-BOP reduction of e.p.s.p. The specific cyclic AMP-dependent protein kinase (PKA) inhibitor, Rp-cyclic adenosine 3',5'-monophosphate (Rp-cyclic AMPS, 25 microM), had no effect on the I-BOP action. 7. In this study we have demonstrated, for the first time, the existence of functional TXA2 receptors in the hippocampus which mediate the effects of a TXA2 agonist on neuronal excitability and synaptic transmission. Activation of the presynaptic TXA2 receptors may stimulate the release of glutamate. Conversely, activation of postsynaptic TXA2 receptors leads to inhibition of synaptic transmission resulting from a decrease in the membrane input resistance of the neurones. The pre- and postsynaptic actions of the TXA2 agonist are both mediated by PTX- and CTX-insensitive G-protein-coupled activation of PKC pathways.

Synthesis of steroid intermediates via alkylation of dianion derived from acetoacetic ester.

A synthetic route for A-ring aromatic steroid intermediates starting from alkylation of dianion derived from acetoacetic ester with m-methoxyphenylethyl bromide to form benzene ring connected to a linear six-carbon fragment is described. This unit, after chemical modifications to 5, was condensed with 2-methylcyclopentan-1,3-dione (6a) to form prochiral trione, 7a, a key synthetic intermediate in A-ring aromatic steroid. Microbial reduction of 7a with Schizosaccharomyces pombe (NRRL Y-164) gave chiral (-)-11 in 65% yield. Starting from 2,2-dimethylsuccinic acid, 2,4,4-trimethylcyclopentan-1,3-dione (6a) was prepared, which was condensed subsequently with 5 to form racemic 7b trione intermediate. Asymmetric cyclization of 7b in the presence of L-(-)-phenylanlanine, followed by acidic cyclization led to regiospecific synthesis of 16,16-dimethyl tetracyclic steroid intermediate.

Characterization of (5Z)-7-[3-endo-[(4-iodophenylsulfonyl) amino] -bicyclo[2.2.1]hep-2-exo-yl]heptenoic acid (IS-145) as an antagonist for the study of thromboxane A2 receptor.

(5Z)-7-[3-endo-[(4-iodophenylsulfonyl) amino]bicyclo[2.2.1]-hep-2-exo-yl] heptenoic acid (IS-145) was characterized on its suitability for the study of thromboxane A2 (TXA2) receptor. Both the I-125 and I-127 analogs are very potent TXA2 antagonist. The I-127 analog interacted with the receptor specifically as shown by the displacement of [3H]-SQ29548 from its binding sites on human platelet membranes in a dose dependent manner. It also elicited specific biological responses by inhibiting I-BOP induced platelet aggregation. However, they failed to inhibit those induced by platelet activating factor. Moreover, it interfered with the TXA2 receptor activated signal transduction system by inhibiting I-BOP induced increase in GTP-gamma-[35S] binding and GTPase activity. These data indicated that IS-145 was indeed a specific antagonist. The I-125 analog was used as a radioactive ligand to characterize TXA2 receptor in human platelet membranes. The binding was found to be saturable, reversible and specific with a KD of 5.8 nM and a Bmax of 1.9 pmol/mg protein.

Improved synthesis of (5Z)-7-(3-endo-[(benzenesulfonamido)-bicyclo[2.2.1]heptyl]hept-5-enoic acid (S-145) derivatives and their iodine-125-labeled radioligands for the study of thromboxane A2 receptor.

An improved synthetic scheme for (5Z)-7-(3-endo-[(benzenesulfonamido)-bicyclo[2.2.1]heptyl)-h ept-5-enoic acid (S145) and its analogs has been designed. The procedure involves direct sulfonylation of 2-allyl-3-aminobicyclo[2.2.1]heptane intermediate followed by ozonolysis and addition of a C5 carboxyl unit. The yield of the final product was significantly improved. (5Z)-7-(3-endo-[(4-iodobenzenesulfonamido)-bicyclo [2.2.1]heptyl)hept-5-enoic acid (HS-145) and (5Z)-7-(3-endo-[(4-hydroxy-benzensulfonamido)-bicyclo [2.2.1]heptyl)hept-5-enoic acid (HS-145) were synthesized directly without any protection and deprotection steps. [125I](5Z)-7-(3-endo-[(4- iodobenzensulfonamido)-bicyclo[2.2.1]heptyl)hept-5-enoic acid ([125I]HS-145) was prepared from IS-145 through an organotin intermediate and [125I]sodium iodide with high specific radioactivity and good recovery of radioactivity. [125I](5Z)-7-(3-endo-[(4-hydroxy 3-iodo-benzenesulfonamido)-bicyclo[2.2.1]-heptyl)hept-5-enoic acid ([125I]HS-145) was prepared by direct iodination with sodium iodide using a modified chloramine-T method. Both [125I]HS-145 and [125I]HS-145 were found to be valuable radioligands for studying thromboxane A2 (TXA2) receptor.

Monoclonal anti-idiotypic antibody to a potent thromboxane A2 receptor antagonist and its interaction with thromboxane A2 receptor.

A monoclonal anti-idiotypic antibody that interacts with thromboxane A2 receptor was generated using an anti-idiotypic approach. Idiotypic antibodies against a potent receptor antagonist, HS-145, were generated in rabbit. The idiotypic antibodies were then selected by an affinity procedure using SQ29,548-Affi-Gel-102 matrix. The selected idiotypic antibodies were used as surrogate receptor for anti-idiotypic antibody generation. A mouse monoclonal antibody, 3D-9E-12, was generated. It was shown to displace 125I-HS-145 from affinity-purified idiotypic antibodies. It also inhibits 125I-IS-145 binding to thromboxane A2 receptor in human platelet membranes in a dose-dependent manner. Furthermore, it attenuated U46,619-induced increase in [35S]guanosine 5'-O-(thiotriphosphate) binding and GTPase activity in human platelet membranes. Finally, it inhibited U46,619- but not PAF-induced platelet aggregation. These results indicate that 3D-9E-12 acts as a specific antagonist in the thromboxane A2 receptor.