Differential induction of androgen receptor transactivation by different androgen receptor coactivators in human prostate cancer DU145 cells

Recently identified androgen receptor (AR) coactivators were used in this study to determine whether the specificity of sex hormones and antiandrogens could be modulated at the coactivator level. We found that ARA70 is the best coactivator to confer the androgenic activity on 17beta-estradiol. Only ARA70 and ARA55 could increase significantly the androgenic activity of hydroxyflutamide, a widely used antiand rogen for the treatment of prostate cancer. None of the AR coactivators we tested could significantly confer androgenic activity on progesterone and glucocorticoid at their physiological concentrations (1-10nM). We also found that ARA70, ARA55, and ARA54, but not steroid receptor coactivator-1 (SRC-1) and Rb, could significantly enhance the delta5-androstenediol-mediated AR transactivation. Furthermore, in comparing the relative specificity of these coactivators to AR in DU145 cells, our results suggested that ARA70 has a relatively higher specificity and that SRC-1 can enhance almost equally well many other steroid receptors. Finally, our data demonstrated that AR itself and some select AR coactivators such as ARA70 or ARA54 could, respectively, interact with CBP and p300/CBP-associated factors that have histone acetyl-transferase activity for assisting chromatin remodeling. Together, our data suggest that the specificity of sex hormones and antiandrogens can be modulated by some selective AR coactivators. These findings may not only help us to better understand the specificity of the sex hormones and antiandrogens, but also facilitate the development of better antiandrogens to fight the androgen-related diseases, such as prostate cancer.

Suppression of Delta(5)-androstenediol-induced androgen receptor transactivation by selective steroids in human prostate cancer cells

Our earlier report suggested that androst-5-ene-3beta,7beta-diol (Delta(5)-androstenediol or Adiol) is a natural hormone with androgenic activity and that two potent antiandrogens, hydroxyflutamide (Eulexin) and bicalutamide (Casodex), fail to block completely the Adiol-induced androgen receptor (AR) transactivation in prostate cancer cells. Here, we report the development of a reporter assay to screen several selective steroids with anti-Adiol activity. Among 22 derivatives/metabolites of dehydroepiandrosterone, we found 4 steroids [no. 4, 1,3,5(10)-estratriene-17alpha-ethynyl-3, 17beta-diol; no. 6, 17alpha-ethynyl-androstene-diol; no. 8, 3beta, 17beta-dihydroxy-androst-5-ene-16-one; and no. 10, 3beta-methylcarbonate-androst-5-ene-7,17-dione] that have no androgenic activity and could also block the Adiol-induced AR transactivation in prostate cancer PC-3 cells. Interestingly, these compounds, in combination with hydroxyflutamide, further suppressed the Adiol-induced AR transactivation. Reporter assays further showed that these four anti-Adiol steroids have relatively lower glucocorticoid, progesterone, and estrogenic activity. Together, these data suggest some selective steroids might have anti-Adiol activity, which may have potential clinical application in the battle against the androgen-dependent prostate cancer growth.

Expression, purification, and functional analysis of murine ectodomain fragments of CD8alphaalpha and CD8alphabeta dimers

Soluble mouse CD8alphaalpha and CD8alphabeta dimers corresponding to the paired ectodomains (CD8(f)) or their respective component Ig-like domains (CD8) were expressed in Chinese hamster ovary cells or the glycosylation variant Lec3.2.8.1 cells as secreted proteins using a leucine zipper strategy. The affinity of CD8alphaalpha(f) for H-2K(b) as measured by BIAcore revealed a approximately 65 microM K(d), similar to that of CD8alphabeta(f). Consistent with this result, CD8alphaalpha(f) as well as CD8alphabeta(f) blocked the effector function of N15 T cell receptor transgenic cytolytic T cells in a comparable, dose-dependent fashion. Furthermore, both Lec3.2.8.1-produced and Chinese hamster ovary-produced CD8 homodimers and heterodimers were active in the inhibition assay. These results suggest that the Ig-like domains of CD8 molecules are themselves sufficient to block the requisite transmembrane CD8-pMHC interaction between cytolytic T lymphocytes and target cells. Moreover, given the similarities in co-receptor affinities for pMHC, the findings suggest that the greater efficiency of CD8alphabeta versus CD8alphaalpha co-receptor function on T cells is linked to differences within their membrane-bound stalk regions and/or intracellular segments. As recently shown for sCD8alphaalpha, the yield, purity and homogeneity of the deglycosylated protein resulting from this expression system is sufficient for crystallization and x-ray diffraction at atomic resolution.

Cyst-like chylous coagulum in the urinary bladder of a patient with recurrent chyluria

We report a rare case of recurrent chyluria in a 64-year-old man, who had undergone sclerosing therapy for chyluria with complete remission 40 years previously. The chyluria recurred 4 months before the present hospital admission. The patient presented with acute urine retention and weight loss of 6 kg during the past 6 months. Urine biochemistry studies showed elevated concentrations of albumin (0.7 g/dL), globulin (0.6 g/dL), cholesterol (0.59 mmol/L), and triglyceride (0.89 mmol/L), confirming the diagnosis of chyluria. Intravenous urography showed a substantial filling defect in the urinary bladder. Cystoscopy revealed milky urine flowing out of the right ureteral orifice, and a large chylous coagulum presenting as a cyst-like mass in the urinary bladder. The chyluria was successfully treated with sclerosing therapy with injection of 76% Urografin (Shering AG, Berlin, Germany) into the right upper urinary tract, and the chylous coagulum was evacuated endoscopically. No evidence of chyluria recurrence has been noted during a year of follow-up, and the patient has regained 6 kg of body weight. This particular presentation of chylous coagulum in a chyluria patient has not been previously reported in the literature.

Risk factors for prostate carcinoma in Taiwan: a case-control study in a Chinese population

BACKGROUND

Although prostate carcinoma remains a rare disease among Chinese men, its incidence is on the rise. The authors conducted a hospital-based case-control study to identify risk factors for prostate carcinoma in northern Taiwan.

METHODS

Patients at a selected veterans hospital or 2 military hospitals who were newly diagnosed with prostate carcinoma between August 1995 and July 1996 were included as cases (n = 90). Controls (n = 180) were comprised noncancer patients who were treated in emergency rooms and departments other than those of urology and cardiology at the same hospitals; controls were matched to cases by age (+/-5 years) and admission date (+/-4 months). Subjects were interviewed in person to elicit information regarding sociodemographic characteristics, life-style, diet, height, and weight.

RESULTS

Cases and controls were similar in terms of age and the majority of sociodemographic characteristics. However, cases tended to have received more education and were less likely to have blue-collar jobs than controls. The consumption of pork was moderately higher for cases than for controls, although this difference was not statistically significant. Cases were more likely than controls to engage in exercise (odds ratio [OR] = 2.16; 95% confidence interval [CI] = 1.18-3.96) and to have a body mass index > or = 24.75 kg/m2 at ages 40-45 years (OR = 2.00; 95%CI = 1.05-3.82). In addition, cases were less likely to cook vegetables with pork lard (OR = 0.47; 95%CI = 0.24-0.91).

CONCLUSIONS

The higher frequency of exercise and lower use of pork lard for cooking among cases reported in the current study suggest that cases tended to have relatively affluent life-styles compared with controls. Because less affluent families are likely to consume more vegetables than meat, these preliminary findings indicate that vegetable intake appears to have a protective effect.

Contents of constituents in mature and immature fruits of evodia species

A total of 33 commercial samples of Evodiae fructus originated from the rutaceous plants Evodia rutaecarpa (Juss.) Benth. and E. rutaecarpa (Juss.) Benth. var. officinalis (Dode) Huang (= E. officinalis Dode), respectively, were collected from Taiwan's herbal market. The contents of eighteen constituents (including 15 alkaloids, 2 flavonoids and 1 diterpenoid) in these samples were determined by high-performance liquid chromatography within 60 minutes. Analysis results showed that the constituent contents were almost unrelated to the species, but rather closely related to the degrees of maturity of the fruit. Those fruits with open mouths and unsplit ovaries had the highest total contents, fruits with open mouths and split ovaries had lower contents, and fruits with closed mouths had the lowest contents. In terms of the individual constituents, the open-mouth fruits contained higher contents of dehydroevodiamine, evodiamine, evocarpine and rutaecarpine, whereas the closed-mouth fruits had higher contents of dehydroevodiamine, epimedoside C, evocarpine and evodiamine.

Unusual Contact-Line Dynamics of Thick Films and Drops

We report several novel phenomena in contact-line and fingering dynamics of macroscopic spinning drops and gravity-driven films with dimensions larger than the capillary length. It is shown through experimental and theoretical analysis that such macroscopic films can exhibit various interfacial shapes, including multi valued ones, near the contact line due to a balance between the external body forces with capillarity. This rich variety of front shapes couples with the usual capillary, viscous, and intermolecular forces at the contact line to produce a rich and unexpected spectrum of contact-line dynamics. A single finger develops when part of the front becomes multivalued on a partially wetting macroscopic spinning drop in contrast to a different mechanism for microscopic drops of completely wetting fluids. Contrary to general expectation, we observe that, at high viscosity and low frequencies of rotation, the speed of a glycerine finger increases with increasing viscosity. Completely wetting Dow Corning 200 Fluid spreads faster over a dry inclined plane than a prewetted one. The presence of a thin prewetted film suppresses fingering both for gravity-driven flow and for spin coating. We analyze some of these unique phenomena in detail and offer qualitative physical explanations for the others. Copyright 1999 Academic Press.

Differential induction of the androgen receptor transcriptional activity by selective androgen receptor coactivators

Several new androgen receptor (AR) cofactors, associated to the ligand binding domain of AR, have been identified by our group and named AR associated protein (ARA)70, ARA55, and ARA54. Our previous reports have suggested that the cofactor ARA70 can confer the androgenic effect from 17 beta-estradiol (E2) and antiandrogen to AR. It is of interest for us to compare and determine if the specificity of sex hormones and antiandrogens could be modulated by different coactivators. Our results indicate that ARA70 is the best coactivator to confer the androgenic activity on E2. Only ARA70 and ARA55 could increase significantly the androgenic activity of hydroxyflutamide, a widely used antiandrogen for the treatment of prostate cancer. Furthermore, as compared to the relative specificity of these coactivators to AR in the prostate cancer DU145 cells, our results suggest that ARA70 has a relatively higher specificity. Together, our data suggest that the specificity of sex hormones and antiandrogens can be modulated by some selective AR coactivators. These findings may not only help us to better understand the specificity of the sex hormones and antiandrogens, but also to facilitate the development of better antiandrogens or androgens to fight the androgen-related diseases, such as prostate cancer.

Pregnane glycosides, gymnepregosides G-Q from the roots of Gymnema alternifolium

The structural elucidation of eleven new related polyoxypregnane glycosides, gymnepregosides G (1), H (2), I (3), J (4), K (5), L (6), M (7), N (8), O (9), P (10) and Q (11), from the roots of Gymnema alternifolium (Asclepiadaceae) was achieved by a detailed study of 1H- and 13C-NMR spectral data and chemical means. The results obtained for new compounds, 1-11, show that they are (20S)-pregn-6-ene-3 beta,5 alpha,8 beta,12 beta,14 beta,17 beta,20-heptaol 3-O-glycosides, and all the sugars at C-3 are beta(i-->4)-linked. Some of them possess benzoyl, (E)- and (Z)-cin-namoyl, and tigloyl residues as the ester linkages located at C-12 and/or C-20 of the aglycone.

Recognition of an MHC class I-restricted antigenic peptide can be modulated by para-substitution of its buried tyrosine residues in a TCR-specific manner

Conformational dependence of TCR contact residues of the H-2Kb molecule on the two buried tyrosine side chains of the vesicular stomatitis virus (VSV)-8 peptide was investigated by systematic substitutions of the tyrosines with phenylalanine, p-fluorophenylalanine (pFF), or p-bromophenylalanine (pBrF). The results of peptide competition CTL assays revealed that all of the peptide variants, except for the pBrF analogues, had near-native binding to the H-2Kb molecule. Epitope-mapped anti-H-2Kb mAbs detected conformational differences among H-2Kb molecules stabilized with these VSV-8 variants on RMA-S cells. Selective recognition of the VSV-8 analogues was displayed by a panel of three H-2Kb-restricted, anti-VSV-8 TCRs. Thus, these substitutions result in an antigenically significant conformational change of the MHC molecular surface structure at both C and D pockets, and the effect of this change on cognate T cell recognition is dependent on the TCR structure. Our results confirm that the structure of buried peptide side chains can determine the surface conformation of the MHC molecule and demonstrate that even a very subtle structural nuance of the buried side chain can be incorporated into the surface conformation of the MHC molecule. The ability of buried residues to modulate this molecular surface augments the number of residues on the MHC-peptide complex that can be recognized as "foreign" by the CD8+ T cell repertoire and allows for a higher level of antigenic discrimination. This may be an important mechanism to expand the total number of TCR specificities that can respond to a single peptide determinant.

Intrathoracic extramedullary haematopoiesis complicated by massive haemothorax in alpha-thalassaemia

Intrathoracic extramedullary haematopoiesis (EMH) is a rare entity that is usually asymptomatic. A 44 year old man with alpha-thalassaemia is described who developed dyspnoea and massive left sided haemothorax. The haemoglobin disorder was established by Hgb H staining and haemoglobin electrophoretic studies. The DNA analysis revealed it to be a case of double heterozygous terminal codon mutation with the genotype alphaalphaCS/alphaalphaT. Computed tomographic scanning and magnetic resonance imaging of the thorax showed multiple paravertebral masses which were found by thoracoscopic biopsy to be extramedullary haematopoiesis. Although no additional sclerosing pleurodesis or low dose radiation therapy was given, the lung expanded well and there has been no recurrence of haemothorax to date.

Cloning and characterization of androgen receptor coactivator, ARA55, in human prostate

Androgen receptor (AR) is a hormone-activated transcriptional factor that can bind to androgen response elements and that regulates the transcription of target genes via a mechanism that presumably involves cofactors. We report here the cloning of a novel AR coactivator ARA55 using a yeast two-hybrid system. ARA55 consists of 444 amino acids with the predicted molecular mass of 55 kDa and its sequence shows very high homology to mouse hic5, a TGF-beta1-inducible gene. Yeast and mammalian two-hybrid systems and co-immunoprecipitation assays all prove ARA55 can bind to AR in a ligand-dependent manner. Transient transfection assay in prostate cancer DU145 cells further demonstrates that ARA55 can enhance AR transcriptional activity in the presence of 1 nM dihydrotestosterone or its antagonists such as 100 nM 17beta-estradiol or 1 microM hydroxyflutamide. Our data also suggest the C-terminal half of ARA55, which includes three LIM motifs, is sufficient to interact with AR. Northern blot and polymerase chain reaction quantitation showed ARA55 can be expressed differently in normal prostate and prostate tumor cells. Together, our data suggests that ARA55 may play very important roles in the progression of prostate cancer by the modulation of AR transactivation.

HELLP syndrome with antepartum pulmonary edema--a case report

A 44-year-old pregnant female with a gestation of 29 weeks suddenly developed abdominal pain, nausea, vomiting, and laboratory study showed anemia, elevated liver enzymes, and lower platelets. HELLP syndrome was diagnosed and urgent delivery was needed. In order to correct the plasma volume and platelet deficiency, 6 units of both fresh frozen plasma and platelets, were given before operation. However, acute pulmonary edema was noted in the antepartum period. After vigorous treatment, she gave birth to a male infant. The postoperative course was smooth and she and her baby were discharged eleven days later. This case reminded us once again of the importance and necessity of invasive monitoring in fluid management of these patients.

Fertilization capability of frozen epididymal sperm for intracytoplasmic sperm injection

Both microsurgical epididymal sperm aspiration (MESA) and intracytoplasmic sperm injection (ICSI) are great advances in assisted reproductive techniques. By using the ICSI technique, frozen sperm from the epididymis can result in successful fertilization. The epididymal sperm retrieved via MESA can be cryopreserved for an in-vitro fertilization (IVF) procedure, thus, making repeat surgical retrieval of sperm unnecessary. We report a retrospective analysis of 24 ICSI cycles in 16 patients with obstructive or nonreconstructable azoospermia. Fresh epididymal sperm was used in 13 ICSI cycles and frozen-thawed epididymal sperm was used in the other 11. We compared the fertilization capability of ICSI using frozen-thawed epididymal sperm with fresh epididymal sperm. Eleven patients became pregnant and five of these pregnancies resulted from frozen epididymal sperm. The fertilization rate per oocyte was 58% with fresh sperm, and 66% with frozen-thawed sperm. The rate of clinical pregnancy for one embryo transfer was 46% with fresh sperm, and 45% with frozen-thawed sperm. There were no significant differences between fresh and frozen-thawed spermatozoa in the fertilization rate of oocytes or the clinical pregnancy rate. Our results suggest that we should cryopreserve supernumerary spermatozoa during a MESA/ICSI procedure in order to avoid repeated scrotal surgery.

Activation of caspase-3-like proteases in apoptosis induced by sphingosine and other long-chain bases in Hep3B hepatoma cells

Sphingosine and other long-chain bases (including sphinganine, dimethylsphingosine and stearylamine), but not octylamine (a short-chain analogue of sphinganine), induced apoptosis in Hep3B hepatoma cells. Because both D- and L-erythrosphingosine and stearylamine exert potent apoptotic effects on Hep3B cells, it is possible that these long-chain bases may activate apoptosis by inhibiting protein kinase C (PKC) activity. However, pretreatment with the PKC activator PMA could not rescue cells from apoptosis triggered by long-chain bases. Therefore the involvement of PKC in this apoptotic process requires further characterization. We also investigated whether these long-chain bases might be metabolized into ceramide in order to elicit their apoptotic action. We found that long-chain bases acted independently of ceramide in the induction of apoptosis, since addition of fumonisin B1, a fungal agent which effectively inhibits ceramide synthesis from sphingosine, did not protect against apoptosis. Additionally, we found that sphingosine-induced apoptosis was accompanied by activation of caspases. The functional role of caspases in this apoptotic process was examined by using specific caspase inhibitors. The general caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp fluoromethyl ketone, which exhibits a broad specificity for caspase-family proteases, effectively blocked sphingosine-induced apoptosis. Furthermore, our results indicate that caspase-3-like proteases, but not caspase-1, are activated during apoptosis triggered by sphingosine. Enhancement of caspase-3-like activity and cleavage of poly(ADP-ribose) polymerase, an in vivo substrate for caspase-3, was clearly demonstrated in sphingosine-treated Hep3B cells. Considered together, these results suggest that caspase-3-like proteases participate in apoptotic cell death induced by sphingosine.

The CD8beta ectodomain contributes to the augmented coreceptor function of CD8alphabeta heterodimers relative to CD8alphaalpha homodimers

Within the lymphoid compartment, CD8 is expressed either as an alphaalpha homodimer or as an alphabeta heterodimer. Prior functional characterization of CD8alpha transfectants has demonstrated that CD8alphaalpha homodimers can reconstitute T cell responses in the absence of the CD8beta subunit. In order to now examine the role of CD8beta in TCR recognition, the CD8alpha cDNA alone or in combination with CD8beta cDNA was transfected into the mouse T cell hybridoma, N15wt, specific for VSV8/Kb. Comparison of antigen-induced IL-2 production reveals that CD8alphabeta+ transfectants are 100-fold more sensitive in molar terms of peptide than CD8alphaalpha+ transfectants. This enhancement of IL-2 production is independent of CD8alpha or CD8beta cytoplasmic tails as demonstrated by analysis of cytoplasmic deletion mutants CD8alpha'beta, CD8alphabeta', and CD8alpha'beta'. These results indicate that the ectodomain of the CD8beta chain greatly enhances the coreceptor function of the CD8alphabeta molecule, at least for certain class I MHC restricted alphabeta TCRs.

CTG repeats show bimodal amplification in E. coli

Trinucleotide repeats in human genetic disorders showing anticipation follow two inheritance patterns as a function of length. Inheritance of 35-50 repeats show incremental changes, while tracts greater than 80 repeats show large saltatory expansions. We describe a bacterial system that recapitulates this striking bimodal pattern of CTG amplification. Incremental expansions predominate in CTG tracts < Okazaki fragment size, while saltatory expansions increase in repeat tracts > or = Okazaki fragment size. CTG amplification requires loss of SbcC, a protein that modulates cleavage of single-stranded DNA and degradation of duplex DNA from double-strand breaks. These results suggest that noncanonical single strand-containing secondary structures in Okazaki fragments and/or double-strand breaks in repeat tracts are intermediates in CTG amplification.

Haematuria clinic--a preliminary audit and considerations for a one-stop assessment centre

AIM

To audit and study the practicality of an integrated Haematuria Clinic as a one-stop assessment centre for the investigations of patients presenting with haematuria.

METHODS

A weekly clinic was organised to facilitate consultation, intravenous urogram and flexible cystoscopy for patients with haematuria. A protocol was set up and data on symptoms, types of haematuria, results of the investigations and outcomes were collected.

RESULTS

About half of all the patients seen in this clinic were found to harbour urological lesions; of which urolithiasis (20.4%) and urological malignancies (14.2%) were the most common lesions identified. Transitional cell carcinoma of the bladder was the most common malignancy diagnosed (8%). Significantly, 2 of 9 (22.2%) bladder cancers were found on cystoscopy and missed on the cystogram phase of the intravenous urogram. Ten urological lesions would have been missed if cystoscopies were not performed. Conversely, in 14 patients, cystoscopy could be avoided because their intravenous urograms identified lesions sufficiently to allow for definitive treatment.

CONCLUSIONS

The need and types of investigation for patients with haematuria are evolving. We recommend intravenous urogram and flexible cystoscopy as the standard investigations and caution against ignoring microscopic haematuria. These assessments can be organised into an integrated clinic improving deliverance of clinical care; which may result in better patient compliance for investigations and earlier detection and treatment of urological lesions presenting as haematuria.

Structural basis of CD8 coreceptor function revealed by crystallographic analysis of a murine CD8alphaalpha ectodomain fragment in complex with H-2Kb

The crystal structure of the two immunoglobulin variable-like domains of the murine CD8alphaalpha homodimer complexed to the class I MHC H-2Kb molecule at 2.8 A resolution shows that CD8alphaalpha binds to the protruding MHC alpha3 domain loop in an antibody-like manner. Comparison of mouse CD8alphaalpha/H-2Kb and human CD8alphaalpha/HLA-A2 complexes reveals shared as well as species-specific recognition features. In both species, coreceptor function apparently involves the participation of CD8 dimer in a bidentate attachment to an MHC class I molecule in conjunction with a T cell receptor without discernable conformational alteration of the peptide or MHC antigen-presenting platform.

The effect of biological dyes and contrast media on the vas deferens in Long Evans rats

The conventional diagnostic procedure of vasography utilizes a contrast medium to evaluate the patency of the vas deferens. With the development of microsurgical reconstruction for obstructive azoospermia in the past two decades, intraoperative vasography with saline or biological dye injection has replaced the use of radiographic contrast media. However, there are few reports on the effect of biological dyes on the healthy vas deferens. Therefore, we used experimental vasography to evaluate histological changes and functional patency of the vas deferens after infusion with a contrast medium and biological dye. Four groups of 10 Long Evans male rats were injected by vasopuncture with 1% methylene blue, 1% gentian violet and 38% Urografin or saline into the vas deferens. The animals were killed 30 days later, and the vasa deferentia were excised and examined for histological changes and for functional patency. Vasopuncture with saline injection induced minimal change both at the puncture site and in the distal vas deferens. In both the Urografin- and methylene blue-injected groups, inflammation at the puncture site was found in 20-22% of cases, and 10-11% of cases revealed functional obstruction of the vasal lumen. In the gentian violet-injected group, severe histological and obliterated changes were found in all cases. Leakage of the dye and contrast medium or the sperm reaction may be responsible for the inflammation; otherwise, methylene blue and urografin did not seem to be harmful to the vas deferens. Although gentian violet is a blue dye, as is methylene blue, it has marked destructive effects on the vas deferens. It is concluded that some biological dyes used for vasal injection can cause occlusion of the vasal lumen, while inflammatory responses can occur from placing a needle transmurally.

Mechanism for inhibition of thyroid peroxidase by leucomalachite green

The triphenylmethane dye, malachite green (MG), is used to treat and prevent fungal and parasitic infections in the aquaculture industry. It has been reported that the reduced metabolite of MG, leucomalachite green (LMG), accumulates in the tissues of fish treated with MG. MG is structurally related to other triphenylmethane dyes (e.g., gentian violet and pararosaniline) that are carcinogenic in the liver, thyroid, and other organs of experimental animals. The ability of LMG to inhibit thyroid peroxidase (TPO), the enzyme that catalyzes the iodination and coupling reactions required for thyroid hormone synthesis, was determined in this study. LMG inhibited TPO-catalyzed tyrosine iodination (half-maximal inhibition at ca. 10 microM). LMG also inhibited the TPO-catalyzed formation of thyroxine in low-iodine human goiter thyroglobulin (half-maximal inhibition at ca. 10 microM) using a model system that measures simultaneous iodination and coupling. Direct inhibition of the coupling reaction by LMG was shown using a coupling-only system containing chemically preiodinated thyroglobulin as the substrate. Incubation of LMG with TPO, iodide, and tyrosine in the presence of a H2O2-generating system yielded oxidation products that were identified by using on-line LC/APCI-MS as desmethyl LMG, 2desmethyl LMG, 3desmethyl LMG, MG, and MG N-oxide. Similar products from LMG were observed in incubations with TPO and H2O2 alone. These findings suggest that the anti-thyroid effects (increased serum thyroid-stimulating hormone and decreased serum thyroxine) observed in rats treated with LMG result from blockade of hormone synthesis through alternate substrate inhibition and that chronic exposure could cause thyroid follicular cell tumors through a hormonal mechanism. The observed TPO-catalyzed oxidative demethylation of LMG to a primary arylamine also suggests a genotoxic mechanism for tumor formation is possible.

Differential thymic selection outcomes stimulated by focal structural alteration in peptide/major histocompatibility complex ligands

The T lineage repertoire is shaped by T cell receptor (TCR)-dependent positive and negative thymic selection processes. Using TCR-transgenic (N15tg) beta2-microglobulin-deficient (beta2m-/-) RAG-2(-/-) H-2(b) mice specific for the VSV8 (RGYVYQGL) octapeptide bound to Kb, we identified a single weak agonist peptide variant V4L (L4) inducing phenotypic and functional T cell maturation. The cognate VSV8 peptide, in contrast, triggers negative selection. The crystal structure of L4/Kb was determined and refined to 2.1 A for comparison with the VSV8/Kb structure at similar resolution. Aside from changes on the p4 side chain of L4 and the resulting alteration of the exposed Kb Lys-66 side chain, these two structures are essentially identical. Hence, a given TCR recognizes subtle distinctions between highly related ligands, resulting in dramatically different selection outcomes. Based on these finding and the recent structural elucidation of the N15-VSV8/Kb complex, moreover, it appears that the germ-line Valpha repertoire contributes in a significant way to positive selection.

In vivo evaluation of serotonergic agents and alpha-adrenergic blockers on premature ejaculation by inhibiting the seminal vesicle pressure response to electrical nerve stimulation

OBJECTIVE

To evaluate the effect of drugs on premature ejaculation using a rat animal model in which the seminal vesicle was electrically stimulated via its lesser splanchnic nerve and changes in the pressure response monitored.

MATERIALS AND METHODS

Male Wistar rats (aged 12-14 weeks) were injected intravenously with prazosin and serotonergic agents (serotonin, clomipramine, fluoxetine, imipramine and indatraline) at various concentrations 10 min before electrical nerve stimulation (ENS) of the lesser splanchnic nerve; the initial increase in seminal vesicle pressure in response to ENS was then compared.

RESULTS

The pressure response to ENS was reduced in the presence of prazosin or serotonergic agents. The mean (SEM) maximum inhibition values were 84.1 (8.9%) by fluoxetine at 0.1 mg/kg, 67.9 (8.7)% by prazosin at 0.1 mg/kg, 60.9 (11.0)% by serotonin at 3 mg/kg, 54.9 (4.6)% by clomipramine at 3 mg/kg, 30.0 (11.0)% by imipramine at 0.1 mg/kg, and 20.9 (4.3)% by indatraline at 0.1 mg/kg. From the concentration-response curve, the potency of prazosin was lower than that of fluoxetine, but was higher than that of serotonin or clomipramine.

CONCLUSIONS

Like serotonin, fluoxetine and clomipramine can reduce the pressure response of the seminal vesicle to ENS. Among these inhibitory agents, including prazosin, fluoxetine was the most effective and may be valuable for the clinical treatment of ejaculatory dysfunction in man.

Pregnane glycosides, gymnepregosides A-F from the roots of Gymnema alternifolium

The structural elucidation of six new related polyoxypregnane glycosides, gymnepregosides A (1), B (2), C (3), D (4), E (5) and F (6), together with two known compounds, from the roots of Gymnema alternifolium (Asclepiadaceae) was achieved through on a detailed study of 1H- and 13C-NMR spectral data and chemical means. The results obtained for new compounds, 1-6, show that they are (20S)-pregn-6-ene-3 beta,5 alpha,8 beta,12 beta,14 beta,17 beta,20-heptaol or sarcostin 3-O-glycosides, and all the sugars at C-3 are beta(1-->4)-linked. Some of them possessed benzoyl, cinnamoyl and tigloyl residues as the ester linkages located at C-12 and/or C-20 of the aglycon.

Beam-propagation method for analysis of z -dependent structures that uses a local oblique coordinate system

In the most current beam-propagation method (BPM), the coupling between the transverse and the longitudinal fields in z -dependent structures is ignored under the staircase approximation, which results in violation of power conservation. We propose a novel BPM that is derived in a local oblique coordinate system to analyze z -dependent structures accurately and efficiently without taking the staircase approximation. The coupling between the transverse and the longitudinal fields is automatically included in the local oblique coordinate system, and power is thus conserved if the reflection is neglected.

Hepatomegaly and multiple liver lesions

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Transforming growth factor beta 1 potently activates CPP32-like proteases in human hepatoma cells

Induction of apoptosis in Hep3B hepatoma cells by transforming growth factor beta 1 (TGF-beta 1) was accompanied by the activation of interleukin-1-beta-converting-enzyme-like proteases, which have recently been renamed as caspases. The caspase inhibitor ZVAD-FMK, which has a broader specificity for caspase family proteases, blocked TGF-beta 1-induced apoptosis in a concentration-dependent manner. The caspases in this apoptotic process were further characterized by using a more specific caspase inhibitor, DEVD-FMK, for CPP32-like (caspase-3-like) proteases. Our results demonstrated that CPP32-like proteases were activated during apoptosis triggered by TGF-beta 1. Enhancement of CPP32-like activity was clearly detected in TGF-beta 1-treated Hep3B cells. Furthermore, cleavage of poly(ADP-ribose) polymerase, an in vivo substrate for CPP32, in these cells was confirmed by immunoblotting. Thus, we suggest that CPP32-like proteases participate in apoptotic cell death induced by TGF-beta 1.

Emotional symptoms are secondary to the voice disorder in patients with spasmodic dysphonia

The aims of this study were to evaluate the emotional status and life quality of the patients with spasmodic dysphonia (SD) before and after botulinum toxin treatment, and to ascertain whether SD is a somatoform disorder. Ten patients with spasmodic dysphonia were injected unilaterally into the vocal cord with botulinum toxin. Before botulinum toxin treatment, two clinician's rating scales--Hamilton Depression Rating Scale (HDRS) and Hamilton Anxiety Rating Scale (HARS), and three self-rating psychometrics--Zung's Self-Rating Depression Scale (SDS), Life Quality Scale (GHQ/QL-12), and Symptom Distress Checklist (SCL-90) were applied. Self-rating scales were also administered in 20 matched normal controls. The patients were reevaluated 1 month after botulinum toxin treatment. The Clinical Global Impression Scale (CGI) was also rated by the patients themselves and a speech pathologist. The mean scores of SD patients were significantly higher than that of controls in SDS, and subscales of somatization, obsessive-compulsive symptoms, depression, anxiety, and psychoticism in SCL-90. The mean score of GHQ/QL-12 was significantly higher in the control group. The scores of HDRS, SDS, GHQ/QL-12 and subscales of somatization, depression, and anxiety in SCL-90 showed significant improvement after botulinum treatment. In CGI, seven patients were rated as improved by patients themselves and the speech pathologist. The patients with SD had more anxiety, depression and somatization symptoms, and poor life quality than normal controls. Their emotional status and life quality improved after botulinum toxin treatment. The results suggest that the emotional symptoms of patients with SD are mainly secondary to voice disorder.

Point mutations in the beta chain CDR3 can alter the T cell receptor recognition pattern on an MHC class I/peptide complex over a broad interface area

To study how the T cell receptor interacts with its cognate ligand, the MHC/peptide complex, we used site directed mutagenesis to generate single point mutants that alter amino acids in the CDR3beta loop of a H-2Kb restricted TCR (N30.7) specific for an immunodominant peptide N52-N59 (VSV8) derived from the vesicular stomatitis virus nucleocapsid. The effect of each mutation on antigen recognition was analyzed using wild type H-2Kb and VSV8 peptide, as well as H-2Kb and VSV8 variants carrying single replacements at residues known to be exposed to the TCR. These analyses revealed that point mutations at some positions in the CDR3beta loop abrogated recognition entirely, while mutations at other CDR3beta positions caused an altered pattern of antigen recognition over a broad area on the MHC/peptide surface. This area included the N-terminus of the peptide, as well as residues of the MHC alpha1 and alpha2 helices flanking this region. Assuming that the N30 TCR docks on the MHC/peptide with an orientation similar to that recently observed in two different TCR-MHC/peptide crystal structures, our findings would suggest that single amino acid alterations within CDR3beta can affect the interaction of the TCR with an MHC surface region distal from the predicted CDR3beta-Kb/VSV8 interface. Such unique recognition capabilities are generated with minimal alterations in the CDR3 loops of the TCR. These observations suggest the hypothesis that extensive changes in the recognition pattern due to small perturbations in the CDR3 structure appears to be a structural strategy for generating a highly diversified TCR repertoire with specificity for a wide variety of antigens.

Differentiation of genuines and counterfeits of Cordyceps species using random amplified polymorphic DNA

For identification of genuine and counterfeit samples of Cordyceps sinensis, an RAPD (random amplified polymorphic DNA) analysis was performed. In the study, twelve samples were collected, of which six were genuine and six were counterfeit samples. Genuine samples of Cordyceps sinensis contain two parasitic larvae produced from each of the three provinces, Sichuan (SC), Chinghai (CH), and Tibet (TB). The counterfeits contain two products of each of the three species, Cordyceps hawkesii, Stachys geobombycis, and Stachys sieboldii. In the RAPD analysis, twenty arbitrary decamer primers were screened to obtain primers appropriate for differentiating the genuine and counterfeit samples. The result of twelve RAPD markers generated from four primers, OPT-08, OPT-12, OPT-13, and OPT-17, were selected. The primers can easily distinguish between genuine and counterfeit samples of Cordyceps sinensis.

Adding ketamine in a multimodal patient-controlled epidural regimen reduces postoperative pain and analgesic consumption

We designed this double-blind study to evaluate the effect of adding small-dose ketamine in a multimodal regimen of postoperative patient-controlled epidural analgesia (PCEA). Ninety-one patients, ASA physical status I-III, undergoing major surgery, received a standardized general anesthesia and epidural catheterization in an appropriate intervertebral space after surgery. A PCEA device was programmed to deliver a regimen of morphine 0.02 mg/mL, bupivacaine 0.8 mg/mL, and epinephrine 4 microg/mL, with the addition of ketamine 0.4 mg/mL (ketamine, n = 45) or without (control, n = 46). The mean visual analog pain scale (VAS) scores during cough or movement for the first 3 days after surgery were higher in the control group than in the ketamine group (P < 0.05), whereas the mean VAS score at rest for the first 2 days were higher in the control group than in the ketamine group (P < 0.05). Furthermore, patients in the control group consumed more multimodal analgesics than patients in the ketamine group for the first 2 days (P < 0.05). The sedation scores and the incidence of side effects (pruritus, nausea, emesis, sleep deprivation, motor block, and respiration depression) were similar between the two groups. We conclude that adding ketamine 0.4 mg/mL in a multimodal PCEA regimen provides better postoperative pain relief and decreases consumption of analgesics.

IMPLICATIONS

Many studies have evaluated one or a combination of two analgesics for postoperative pain control, but few have examined a multimodal approach using three or four different epidural analgesics. This study demonstrates an additive analgesic effect when ketamine is added to a multimodal analgesic treatment.

Effects of Chinese herbal prescriptions on copulatory activity in aged male rats: a preliminary study

Four herbal prescription medicines, Chi-Pao-Mei-Jan-Tan, Gui-Fu-Ba-Wei-Wan, Huan-Shao-Tan; and San Tsai-Feng-Sui-Tan, were tested for their effects on sexual behavior in aged rats. Crude liquid extracts of these herbs were administered to the rats daily through oral tubing for 14 days. All four herbal prescriptions showed some effects in restoration of mount and intromission behaviors, but there was no effect on restoration of ejaculation in 26 month old rats that had exhibited no copulatory activity (no mount, intromission and ejaculation) previously. The effects of Chi-Pao-Mei-Jan-Tan were further tested in 26 month old rats with low mount and intromission activities but without ejaculation behavior, and in 15 month old rats (middle-age group) that showed normal mount and intromission behavior but no ejaculation activity. Chi-Pao-Mei-Jan-Tan was effective in improving the frequency of both mount and intromission, but failed to restore the ejaculation activity of the old rats with low mount and intromission behaviors. It was, however, very effective in restoration of ejaculation activity in middle-aged rats that exhibited normal mount and intromission behaviors. Serum testosterone (T) levels of Chi-Pao-Mei-Jan-Tan in tested old and middle-aged rats were determined by radioimmunoassay, and showed no difference before and after treatment. Our findings demonstrated that the four herbal prescriptions had some effects in restoration of mount and intromission behaviors, but not ejaculation activity in old rats, and that Chi-Pao-Mei-Jan-Tan was very effective in restoration of ejaculation activity in middle-aged rats. The promotional effect of Chi-Pao-Mei-Jan-Tan on copulatory behavior was not correlated with serum T levels.

One of the CD3epsilon subunits within a T cell receptor complex lies in close proximity to the Cbeta FG loop

A recent crystal structure of the N15 alpha/beta-T cell receptor (TCR) in complex with an Fab derived from the H57 Cbeta-specific monoclonal antibody (mAb) shows the mAb fragment interacting with the elongated FG loop of the Cbeta domain. This loop creates one side wall of a cavity within the TCR Ti-alpha/beta constant region module (CalphaCbeta) while the CD and EF loops of the Calpha domain form another wall. The cavity size is sufficient to accommodate a single nonglycosylated Ig domain such as the CD3epsilon ectodomain. By using specific mAbs to mouse TCR-beta (H57) and CD3epsilon (2C11) subunits, we herein provide evidence that only one of the two CD3epsilon chains within the TCR complex is located in close proximity to the TCR Cbeta FG loop, in support of the above notion. Moreover, analysis of T cells isolated from transgenic mice expressing both human and mouse CD3epsilon genes shows that the heterologous human CD3epsilon component can replace the mouse CD3epsilon at this site. The location of one CD3epsilon subunit within the rigid constant domain module has implications for the mechanism of signal transduction throughout T cell development.

The peptidyl-prolyl isomerase domain of the CyP-40 cyclophilin homolog Cpr7 is not required to support growth or glucocorticoid receptor activity in Saccharomyces cerevisiae

CyP-40 cyclophilins are found in association with molecular chaperone Hsp90.steroid receptor complexes. The amino-terminal portion of these cyclophilins harbors the characteristic peptidyl-prolyl isomerase (PPIase) domain, whereas three copies of the tetratricopeptide (TPR) motif, a structure shown to be involved in protein-protein interactions, and a putative calmodulin-binding domain are located in the carboxyl-terminal half of the protein. The TPR domains mediate binding to Hsp90, but a requirement for the PPIase domain has not been established. To address this, we have investigated the effects of mutations that alter the PPIase domain of the Saccharomyces cerevisiae CyP-40 homolog, Cpr7. Because Cpr7 is required for rapid growth and full Hsp90 activity, a functional assessment of the PPIase domain could be performed in vivo. A mutation in the catalytic domain altering a conserved site predicted to be essential for isomerase activity did not compromise Cpr7 function. Furthermore, deletion of the entire PPIase domain did not significantly affect growth or Hsp90-mediated steroid receptor activity. These results indicate that the TPR-containing carboxyl terminus of Cpr7 is sufficient for fundamental Cpr7-dependent activity.

Determination of acceptability of flavored oat bran frankfurters by older adults

The US population is aging rapidly and, within the next 25 years, 20-25% will be over age 60. This creates a vast new market for age-specific products and increases the responsibility of food scientists and nutritionists to provide appropriate foods for older adults. Many older individuals are energy deficient and need to be encouraged to consume more food in order to maintain body weight and health, but need to decrease the calories from fat in their diets. Many of these older individuals are not inclined to eat foods that they enjoy for fear that these foods may be detrimental to their health (de Castro, 1993), or they have lost their gustational abilities to the degree that these foods are no longer enjoyable. This research looks at a possible solution to both problems by replacing fat in a favorite food of older adults and adjusting the flavor levels of this product. Frankfurters were made from mechanically deboned poultry meat in which standard commercial formulation was compared to three flavoring treatments using oat bran as a fat replacer (6% oat bran, 30% H2O). Mixed spices (traditional saucisson) were added to two of these treatments in standard and double proportions. Participants were 71 individuals over the age of 65 in varying levels of health from four regional care facilities. Seven gram, three-digit-coded samples were evaluated at 60 degrees C, and scored on a nine-point hedonic scale. A significant (alpha = 0.0004) preference was shown for the double-spiced frank. No differences by sex or race were found. Research concluded that addition of flavoring aids in the increased acceptability of products by older adults.

Peroxidase-catalyzed oxidation of 2,4,6-trichlorophenol

2,4,6-Trichlorophenol (TCP) is an environmental contaminant that is toxic, mutagenic, and carcinogenic. We have investigated peroxidase-catalyzed oxidation of TCP as an alternative pathway of TCP bioactivation using horseradish peroxidase (HRP) as a model peroxidase. TCP was shown to function as a reducing substarte for HRP as evidenced by TCP-dependent, HRP-catalyzed reduction of 5-phenyl-4-penten-1-yl hydroperoxide (PPHP) to its corresponding alcohol. In addition, TCP was shown to undergo hydroperoxide (H2O2, ethyl hydroperoxide, or PPHP)-dependent metabolism as evidenced by electronic absorption spectroscopic analysis of reaction mixtures. A single major product was detected by reverse phase HPLC and was identified as 2,6-dichloro-1,4-benzoquinone (2,6-dichloro-2, 5-cyclohexadiene-1,4-dione, CAS no. 697-91-6) on the basis of electronic absorption spectroscopy, mass spectrometry, and cochromatography with synthetic standard. In addition, HRP-catalyzed oxidation of TCP yielded EPR-detectable phenoxyl radical intermediates whose EPR spectrum consisted of a 1:2:1 triplet characterized by proton hyperfine coupling constants aH(3,5) = 2.35 gauss. Mechanisms for the hydroperoxide-dependent, HRP-catalyzed oxidation of TCP are proposed that are consistent with these results.

Identification of a common docking topology with substantial variation among different TCR-peptide-MHC complexes

Whether T-cell receptors (TCRs) recognize antigenic peptides bound to major histocompatability complex (MHC) molecules through common or distinct docking modes is currently uncertain. We report the crystal structure of a complex between the murine N15 TCR [1-4] and its peptide-MHC ligand, an octapeptide fragment representing amino acids 52-59 of the vesicular stomatitis virus nuclear capsid protein (VSV8) bound to the murine H-2Kb class I MHC molecule. Comparison of the structure of the N15 TCR-VSV8-H-2Kb complex with the murine 2C TCR-dEV8-H-2Kb [5] and the human A6 TCR-Tax-HLA-A2 [6] complexes revealed a common docking mode, regardless of TCR specificity or species origin, in which the TCR variable Valpha domain overlies the MHC alpha2 helix and the Vbeta domain overlies the MHC alpha1 helix. As a consequence, the complementary determining regions CDR1 and CDR3 of the TCR Valpha and Vbeta domains make the major contacts with the peptide, while the CDR2 loops interact primarily with the MHC. Nonetheless, in terms of the details of the relative orientation and disposition of binding, there is substantial variation in TCR parameters, which we term twist, tilt and shift, and which define the variation of the V module of the TCR relative to the MHC antigen-binding groove.

Sialadenoma papilliferum of the esophagus

Sialadenoma papilliferum is an extremely rare benign tumor of the esophagus. We report a 70-yr-old woman who was first thought to have adenocarcinoma in the distal esophagus. Transhiatal esophagectomy and left colon interposition were performed. The pathological diagnosis of sialadenoma papilliferum of the esophagus arising in the submucosal gland ducts was confirmed after surgery.

Comparison of hemodynamics and recovery of sevoflurane and isoflurane anesthesia in Chinese adult patients

BACKGROUND

The new inhalational anesthetic sevoflurane would be expected to provide a rapid emergence from anesthesia due to its low blood/gas partition coefficient. In this study, we compared the hemodynamic effects, speed and quality of emergence, in ASA class I-II Chinese adult surgical patients receiving either sevoflurane or isoflurane anesthesia.

METHODS

Eighty adult Chinese patients, ASA class I-II, scheduled for elective gynecological or general surgical procedures, were randomized to receive sevoflurane (n = 40) or isoflurane (n = 40) anesthesia. Ventilation is controlled via endotracheal intubation with anesthesia facilitated by either agent at anesthetic concentration of 1-1.5 MAC under the fresh gas flow 2 L/min. Heart rate, arterial blood pressure, temperature, SpO2 and end-tidal CO2 were continuously monitored. Any adverse effect such as airway irritation, nausea or vomiting was recorded during induction and emergence from anesthesia. The emergence time was assessed by various questionales for orientation during recovery. In the post-anesthetic recovery period, pain was monitored and managed by objective pain discomfort scale for analgesic supplements. Complaints of nausea and vomiting were recorded and followed up by a research nurse who visited the patient within 24 h following surgery.

RESULTS

The extent of exposure to anesthetic (MAC x hours) was similar in both groups. Sevoflurane and isoflurane caused similar alterations in systolic and diastolic arterial pressure during maintenance. After surgical incision, the heart rate accelerated more in patients receiving isoflurane (p < 0.05). During emergence, time of response to command was significantly shorter in patients receiving sevoflurane than patients receiving isoflurane (5.6 +/- 0.4 min versus 15.2 +/- 3.0 min, p < 0.001). Side effects such as nausea and vomiting were comparable in both groups.

CONCLUSIONS

Compared with isoflurane, sevoflurane anesthesia had the clinical advantages of maintaining stable hemodynamics and rapid recovery in Chinese adult patients.

A piezoelectric quartz crystal sensor for the determination of coagulation time in plasma and whole blood

A Peizoelectric Quartz Crystal (PQC) system possessing an adequate sensitivity to a slight viscosity change is employed to monitor the blood coagulation. In the case of an anticoagulated plasma specimen, prothrombin time (PT) was determined by the PQC sensor on the basis of the introduction of tissue thromboplastin (TF) and calcium ion. Discussing the PQC data statistically, we found that at 90% of the total frequency shift (delta f) the best linear relationship in a double-logarithmic plot of PT versus TF concentration in the range of 5.466-22.311 unit/ml is shown. The PQC result was compared with commercial optical coagulometry and showed a good linear correlation (ca. 0.98). The clotting and recalcification of whole blood were also studied by the PQC system. The testing time for one measurement could be completed within 20 min. and had a good agreement with that obtained conventionally.

Pregnancy achieved by intracytoplasmic sperm injection using cryopreserved vasal-epididymal sperm from a man with spinal cord injury

Anejaculation and poor semen quality are two major causes of infertility in men with spinal cord injury (SCI). The poor motility of retrieved sperm usually has low fertilization potential and is thought to be unfavorable for cryopreservation. This report describes a pregnancy after intracytoplasmic sperm injection (ICSI) with cryopreserved vasal-epididymal sperm from a man with SCI and anejaculation. An attempt was made to obtain sperm through electroejaculation, but no motile sperm were found in two trials. Therefore, the subject underwent vasal aspiration. The retrieved sperm had a concentration of 26 x 10(6)/mL and a motility of 3%. ICSI was considered to be the best choice for the couple, but the wife did not become pregnant in the first cycle of treatment. A successful pregnancy was achieved by ICSI in the second cycle using frozen-thawed sperm, supernumerary in the previous cycle, with a density of 5 x 10(6)/mL and 1% motility. A set of healthy twins, one boy and one girl, were delivered via cesarean section at 36 weeks of gestation. Complementary to other assisted reproductive techniques, ICSI may provide men with SCI a greater opportunity to father children. The supernumerary sperm, regardless of quality, should be cryopreserved to avoid the necessity and risk of repeated assisted ejaculations and aspirations of the genital tract.

Atomic structure of an alphabeta T cell receptor (TCR) heterodimer in complex with an anti-TCR fab fragment derived from a mitogenic antibody

Each T cell receptor (TCR) recognizes a peptide antigen bound to a major histocompatibility complex (MHC) molecule via a clonotypic alphabeta heterodimeric structure (Ti) non-covalently associated with the monomorphic CD3 signaling components. A crystal structure of an alphabeta TCR-anti-TCR Fab complex shows an Fab fragment derived from the H57 monoclonal antibody (mAb), interacting with the elongated FG loop of the Cbeta domain, situated beneath the Vbeta domain. This loop, along with the partially exposed ABED beta sheet of Cbeta, and glycans attached to both Cbeta and Calpha domains, forms a cavity of sufficient size to accommodate a single non-glycosylated Ig domain such as the CD3epsilon ectodomain. That this asymmetrically localized site is embedded within the rigid constant domain module has implications for the mechanism of signal transduction in both TCR and pre-TCR complexes. Furthermore, quaternary structures of TCRs vary significantly even when they bind the same MHC molecule, as manifested by a unique twisting of the V module relative to the C module.

Topology of NAT2, a prototypical example of a new family of amino acid transporters

Amino acids are the predominant form of nitrogen available to the heterotrophic tissues of plants. These essential organic nutrients are transported across the plasma membrane of plant cells by proton-amino acid symporters. Our lab has cloned an amino acid transporter from Arabidopsis, NAT2/AAP1, that represents the first example of a new class of membrane transporters. We are investigating the structure and function of this porter because it is a member of a large gene family in plants and because its wide expression pattern suggests it plays a central role in resource allocation. In the results reported here, we investigated the topology of NAT2 by engineering a c-myc epitope on either the N or C terminus of the protein. We then used in vitro translation, partial digestion with proteinase K, and immunoprecipitation to identify a group of oriented peptide fragments. We modeled the topology of NAT2 based on the lengths of the peptide fragments that allowed us to estimate the location of protease accessible cleavage sites. We independently identified the location of the N and C termini using immunofluorescence microscopy of NAT2 expressed in COS-1 cells. We also investigated the glycosylation status of several sites of potential N-linked glycosylation. Based on the combined data, we propose a novel 11 transmembrane domain model with the N terminus in the cytoplasm and C terminus facing outside the cell. This model of protein topology anchors our complementary investigations of porter structure and function using site-directed and random mutagenesis.

Anti-thyroid isoflavones from soybean: isolation, characterization, and mechanisms of action

The soybean has been implicated in diet-induced goiter by many studies. The extensive consumption of soy products in infant formulas and in vegetarian diets makes it essential to define the goitrogenic potential. In this report, it was observed that an acidic methanolic extract of soybeans contains compounds that inhibit thyroid peroxidase- (TPO) catalyzed reactions essential to thyroid hormone synthesis. Analysis of the soybean extract using HPLC, UV-VIS spectrophotometry, and LC-MS led to identification of the isoflavones genistein and daidzein as major components by direct comparison with authentic standard reference isoflavones. HPLC fractionation and enzymatic assay of the soybean extract showed that the components responsible for inhibition of TPO-catalyzed reactions coeluted with daidzein and genistein. In the presence of iodide ion, genistein and daidzein blocked TPO-catalyzed tyrosine iodination by acting as alternate substrates, yielding mono-, di-, and triiodoisoflavones. Genistein also inhibited thyroxine synthesis using iodinated casein or human goiter thyroglobulin as substrates for the coupling reaction. Incubation of either isoflavone with TPO in the presence of H2O2 caused irreversible inactivation of the enzyme; however, the presence of iodide ion in the incubations completely abolished the inactivation. The IC50 values for inhibition of TPO-catalyzed reactions by genistein and daidzein were ca. 1-10 microM, concentrations that approach the total isoflavone levels (ca. 1 microM) previously measured in plasma from humans consuming soy products. Because inhibition of thyroid hormone synthesis can induce goiter and thyroid neoplasia in rodents, delineation of anti-thyroid mechanisms for soy isoflavones may be important for extrapolating goitrogenic hazards identified in chronic rodent bioassays to humans consuming soy products.

HIV-1 Tat protein exits from cells via a leaderless secretory pathway and binds to extracellular matrix-associated heparan sulfate proteoglycans through its basic region

OBJECTIVE

To analyze the mechanisms of release and the extracellular fate of the HIV-1 Tat protein and to determine the Tat domain binding to the extracellular matrix.

DESIGN AND METHODS

Release of Tat was studied by pulse-chase experiments with Tat-transfected COS-1 cells in the presence or absence of different serum concentrations, temperatures and drugs inhibiting the classical secretion pathway or endo-exocytosis, such as brefeldin A and methylamine. The binding of extracellular Tat to heparan sulfate proteoglycans (HSPG) was determined by using trypsin, heparin or heparinase in pulse-chase experiments, by gel shift and competition assays with radiolabeled heparin, and by heparin-affinity chromatography. The mapping of the Tat binding site to heparin was defined by functional assays of rescue of Tat-defective HIV-1 proviruses.

RESULTS

Tat is released in the absence of cell death or permeability changes. Tat release is dependent upon the temperature and serum concentration, and it is not blocked by brefeldin A or methylamine. After release, a portion of the protein remains in a soluble form whereas the other binds to extracellular matrix (ECM)-associated HSPG. The HSPG-bound Tat can be retrieved into a soluble form by heparin, heparinase or trypsin. Binding to heparin is competed out by heparin-binding factors such as basic fibroblast growth factor (bFGF), and it is mediated by the Tat basic region which forms a specific complex with heparin which blocks HIV-1 rescue by exogenous Tat and allows purification of a highly biologically active protein.

CONCLUSIONS

These results demonstrate that Tat exits from intact cells through a leaderless secretion pathway which shares several features with that of acid FGF or bFGF. The released Tat binds to HSPG through its basic region and this determines its storage into the ECM, as occurs for bFGF.

Identification and differentiation of bear bile used in medicinal products in Taiwan

One hundred eighty-three suspect bear bile used in medicinal products, collected in Taiwan as gall bladders or dried powder forms, were analyzed using FTIR, HPTLC, and HPLC techniques to identify whether they are indeed bear bile. Those confirmed were further examined to determine whether the observed analytical parameters can be reliably used for source inference, i.e., differentiating products among North American black bear, farmed Asiatic black bear, polar bear, etc. Our data suggested that North American and polar bears contain a higher concentration of TC (relative to TUDC and TCDC), whereas the relative concentration of TC in Asiatic bears (wild or farmed) is much lower. Thus, the relative concentration of TC can potentially be used for differentiating Asiatic bear bile from North American and polar bear products, but it cannot be used for the differentiation of wild and farmed bear bile as suggested in an earlier report by Espinoza et al. The origin of the 183 samples analyzed were found to be as follows: 118 (64%), bile salts, or gall bladders were of domestic pig; 56 (31%), bile products of Asiatic bear; 4 (2.2%), Asiatic bear mixed with pig bile salts; 3 (1.6%) goat gall bladders; 1 (0.55%) water buffalo bile salts; and 1 (0.55%), pig bile salts mixed with water buffalo bile salts.

Double-positive T cell receptor(high) thymocytes are resistant to peptide/major histocompatibility complex ligand-induced negative selection

To investigate negative selection events during intrathymic ontogeny, we established T cell receptor (TCR)-transgenic mice [N15tg/RAG-2-/- (H-2b)] expressing a single TCR specific for vesicular stomatitis virus nuclear octapeptide N52-59 (VSV8) in the context of the major histocompatibility complex (MHC) class I molecule, K(b). Administration of VSV8 in vivo induced apoptosis in less than 4 h, deleting the majority of immature double-positive (DP) thymocytes by 24 h. In contrast, DP TCRhigh as well as single-positive (SP) thymocytes were refractory to this death process. Moreover, DP TCRhigh cells differentiated into SP thymocytes in vitro and in vivo, maturing into functional cytotoxic T lymphocytes upon intrathymic transfer to beta RAG 2-/- recipients. Hence, negative selection processes involving MHC-bound peptide ligands are operative only prior to the late DP thymocyte stage in this MHC class I-restricted TCR transgene system.

Topology of T cell receptor-peptide/class I MHC interaction defined by charge reversal complementation and functional analysis

The molecular interactions between the CD8 co-receptor dependent N15 and N26 T cell receptors (TCRs) and their common ligand, the vesicular stomatitis virus octapeptide (VSV8) bound to H-2Kb, were studied to define the docking orientation(s) of MHC class I restricted TCRs during immune recognition. Guided by the molecular surfaces of the crystallographically defined peptide/MHC and modeled TCRs, a series of mutations in exposed residues likely contacting the TCR ligand were analyzed for their ability to alter peptide-triggered IL-2 production in T cell transfectants. Critical residues which diminished antigen recognition by 1000 to 10,000-fold in molar terms were identified in both N15 Valpha (alphaE94A or alphaE94R, Y98A and K99) and Vbeta (betaR96A, betaW97A and betaD99A) CDR3 loops. Mutational analysis indicated that the Rp1 residue of VSV8 is critical for antigen recognition of N15 TCR, but R62 of H-2Kb is less critical. More importantly, the alphaE94R mutant could be fully complemented by a reciprocal charge reversal at Kb R62 (R62E). This result suggests a direct interaction between N15 TCR Valpha E94R and Kb R62E residues. As Rp1 of VSV8 is adjacent to R62 in the VSV8/Kb complex and essential for T cell activation, this orientation implies that the N15 Valpha CDR3 loop interacts with the N-terminal residues of VSV8 with the Valpha domain docking to the Kb alpha2 helix while the N15 Vbeta CDR3 loop interacts with the more C-terminal peptide residues and the Vbeta domain overlies the Kb alpha1 helix. An equivalent orientation is suggested for N26, a second VSV8/Kb specific TCR. Given that genetic analysis of two different class II MHC-restricted TCRs and two crystallographic studies of class I restricted TCRs offers a similar overall orientation of V domains relative to alpha-helices, these data raise the possibility of a common docking mode between TCRs and their ligands regardless of MHC restriction.

Efficient beam-propagation method based on Padé approximants in the propagation direction

We propose a novel beam-propagation method (BPM) based on the higher-order Padé approximants in both the transverse and the longitudinal directions. Extending the Padé approximation to the propagation direction and adopting the multistep method increase the programming effort by only a small amount. Compared with the conventional BPM's, this method is more accurate and efficient. The accuracy and the propagation step size are well predicted by a phase analysis.