Cyclopia extracts act as selective estrogen receptor subtype downregulators in estrogen receptor positive breast cancer cell lines: Comparison to standard of care breast cancer endocrine therapies and a selective estrogen receptor agonist and antagonist

Breast cancer is the most diagnosed type of cancer amongst women in economically developing countries and globally. Most breast cancers express estrogen receptor alpha (ERα) and are categorized as positive (ER+) breast cancer. Endocrine therapies such as, selective estrogen receptor modulators (SERMs), aromatase inhibitors (AIs), and selective estrogen receptor downregulators (SERDs) are used to treat ER+ breast cancer. However, despite their effectiveness, severe side-effects and resistance are associated with these endocrine therapies. Thus, it would be highly beneficial to develop breast cancer drugs that are as effective as current therapies, but less toxic with fewer side effects, and less likely to induce resistance. Extracts of Cyclopia species, an indigenous South African fynbos plant, have been shown to possess phenolic compounds that exhibit phytoestrogenic and chemopreventive activities against breast cancer development and progression. In the current study, three well characterized Cyclopia extracts, SM6Met, cup of tea (CoT) and P104, were examined for their abilities to modulate the levels of the estrogen receptor subtypes, estrogen receptor alpha and estrogen receptor beta (ERβ), which have been recognized as crucial to breast cancer prognosis and treatment. We showed that the Cyclopia subternata Vogel (C. subternata Vogel) extracts, SM6Met and cup of tea, but not the C. genistoides extract, P104, reduced estrogen receptor alpha protein levels while elevating estrogen receptor beta protein levels, thereby reducing the ERα:ERβ ratio in a similar manner as standard of care breast cancer endocrine therapies such as fulvestrant (selective estrogen receptor downregulator) and 4-hydroxytamoxifen (elective estrogen receptor modulator). Estrogen receptor alpha expression enhances the proliferation of breast cancer cells while estrogen receptor beta inhibits the proliferative activities of estrogen receptor alpha. We also showed that in terms of the molecular mechanisms involved all the Cyclopia extracts regulated estrogen receptor alpha and estrogen receptor beta protein levels through both transcriptional and translational, and proteasomal degradation mechanisms. Therefore, from our findings, we proffer that the C. subternata Vogel extracts, SM6Met and cup of tea, but not the C. genistoides extract, P104, selectively modulate estrogen receptor subtypes levels in a manner that generally supports inhibition of breast cancer proliferation, thereby demonstrating attributes that could be explored as potential therapeutic agents for breast cancer.

Combinatorial treatments of tamoxifen and SM6Met, an extract from Cyclopia subternata Vogel, are superior to either treatment alone in MCF-7 cells

Synergistic drug combinations are not only popular in antibiotic, anti-microbial, immune disease (i.e., AIDS) and viral infection studies, but has also gained traction in the field of cancer research as a multi-targeted approach. It has the potential to lower the doses needed of standard of care (SOC) therapeutic agents, whilst maintaining an effective therapeutic level. Lower dosages could ameliorate the fundamental problems such as drug resistance and metastasis associated with current SOC therapies. In the current study, we show that the combination of SM6Met with (2)-4-hydroxytamoxifen (4-OH-Tam, the active metabolite of tamoxifen) produces a strong synergistic effect in terms of inhibiting MCF7 ER-positive (ER⁺) breast cancer cell proliferation and that a 20 times lower dose of 4-OH-Tam in combination with SM6Met is required to produce the same inhibitory effect on cell proliferation as 4-OH-Tam on its own. Cell cycle analyses of the best combination ratios of SM6Met and 4-OH-Tam also suggests that the combination results in increased accumulation of cells in the S-phase and in the apoptotic phase. Moreover, the best combination ratio (20:1) of SM6Met with 4-OH-Tam displayed greater anti-metastatic potential in terms of inhibiting ER⁺ breast cancer cell migration, invasion, and colony formation than the SOC therapy alone, suggesting that SM6Met together with 4-OH-Tam could be a viable drug combination for not only delaying resistance and ameliorating the negative side-effects associated with current SOC therapies, like tamoxifen, but could also provide a novel, more affordable therapeutic alternative for treating or preventing ER⁺ breast cancer metastasis.

The Association of Acute Phase Proteins in Stress and Inflammation-Induced T2D

Acute phase proteins (APPs), such as plasminogen activator inhibitor-1 (PAI-1), serum amyloid A (SAA), and C-reactive protein (CRP), are elevated in type-2 diabetes (T2D) and are routinely used as biomarkers for this disease. These APPs are regulated by the peripheral mediators of stress (i.e., endogenous glucocorticoids (GCs)) and inflammation (i.e., pro-inflammatory cytokines), with both implicated in the development of insulin resistance, the main risk factor for the development of T2D. In this review we propose that APPs, PAI-1, SAA, and CRP, could be the causative rather than only a correlative link between the physiological elements of risk (stress and inflammation) and the development of insulin resistance.

Relative contribution of molecular mechanisms to cumulative ligand-mediated downregulation of GRα

Central to the pharmacological use of glucocorticoids (GCs) is the availability of the glucocorticoid receptor alpha (GRα). However, chronic GC therapy often results in the ligand-mediated downregulation of the GRα, and the subsequent development of an acquired GC resistance. While studies have demonstrated the dimerization-dependent downregulation of GRα, as well as the molecular mechanisms through which ligand-mediated downregulation occurs, little is known regarding the relative contribution of these molecular mechanisms to the cumulative ligand-mediated downregulation of the receptor, especially within an endogenous system. Thus, to probe this, the current study evaluates the conformational-dependent regulation of GRα protein using mouse embryonic fibroblast (MEF) cells containing either wild type GRα (MEFwt) or the dimerization deficient GRα mutant (MEFdim) and inhibitors of transcription, translation, and proteasomal degradation. Results show that the promotion of GRα dimerization increases the downregulation of the receptor via two main mechanisms, proteasomal degradation of the receptor protein, and downregulation of GRwt mRNA transcripts. In contrast, when receptor dimerization is restricted these two mechanisms play a lesser role and results suggest that stabilization of GRα protein by non-coding RNAs may potentially be the major regulatory mechanism. Together, these findings clarify the relative contribution of the molecular mechanisms involved in ligand-mediated downregulation of GRα and provides pharmacological targets for the development of GRα ligands with a more favourable therapeutic index.

Point mutation I634A in the glucocorticoid receptor causes embryonic lethality by reduced ligand binding

The glucocorticoid (GC) receptor (GR) is essential for normal development and in the initiation of inflammation. Healthy GR^dim/dim mice with reduced dimerization propensity due to a point mutation (A465T) at the dimer interface of the GR DNA-binding domain (DBD) (here GR^D/D) have previously helped to define the functions of GR monomers and dimers. Since GR^D/D retains residual dimerization capacity, here we generated the dimer-nullifying double mutant GR^D+L/D+L mice, featuring an additional mutation (I634A) in the ligand-binding domain (LBD) of GR. These mice are perinatally lethal, as are GR^L/L mice (these mice have the I634A mutation but not the A465T mutation), displaying improper lung and skin formation. Using embryonic fibroblasts, high and low doses of dexamethasone (Dex), nuclear translocation assays, RNAseq, dimerization assays, and ligand-binding assays (and K_d values), we found that the lethal phenotype in these mice is due to insufficient ligand binding. These data suggest there is some correlation between GR dimerization potential and ligand affinity. We conclude that even a mutation as subtle as I634A, at a position not directly involved in ligand interactions sensu stricto, can still influence ligand binding and have a lethal outcome.

Acquired Glucocorticoid Resistance Due to Homologous Glucocorticoid Receptor Downregulation: A Modern Look at an Age-Old Problem

For over 70 years, the unique anti-inflammatory properties of glucocorticoids (GCs), which mediate their effects via the ligand-activated transcription factor, the glucocorticoid receptor alpha (GRα), have allowed for the use of these steroid hormones in the treatment of various autoimmune and inflammatory-linked diseases. However, aside from the onset of severe side-effects, chronic GC therapy often leads to the ligand-mediated downregulation of the GRα which, in turn, leads to a decrease in GC sensitivity, and effectively, the development of acquired GC resistance. Although the ligand-mediated downregulation of GRα is well documented, the precise factors which influence this process are not well understood and, thus, the development of an acquired GC resistance presents an ever-increasing challenge to the pharmaceutical industry. Recently, however, studies have correlated the dimerization status of the GRα with its ligand-mediated downregulation. Therefore, the current review will be discussing the major role-players in the homologous downregulation of the GRα pool, with a specific focus on previously reported GC-mediated reductions in GRα mRNA and protein levels, the molecular mechanisms through which the GRα functional pool is maintained and the possible impact of receptor conformation on GC-mediated GRα downregulation.

Laterality judgement and tactile acuity in patients with frozen shoulder: A cross-sectional study

BACKGROUND

Disrupted tactile acuity and poor laterality judgement have been shown in several chronic musculoskeletal pain conditions. Whether they are impaired in people with frozen shoulder (FS) remains unknown.

OBJECTIVES

To determine whether there is impairment in tactile acuity and laterality judgement in subjects with FS.

METHODS

Thirty-eight subjects with idiopathic FS and 38 sex and age-matched healthy controls were enrolled. The two-point discrimination threshold (TPDT) over the affected and unaffected shoulder of patients with FS and shoulder of healthy controls was evaluated. In addition, all participants performed a left/right judgment task (LRJT). Independent and dependent t-tests were used to compare group means. Pearson-product moment coefficient correlations between pain intensity and duration and LRJT and TPDT were calculated for the FS group.

RESULTS

The TPDT over the affected shoulder was significantly increased compared to the unaffected shoulder (mean difference, 3.82 mm; 95% confidence interval [CI]:0.53, 7.10; p = .02) and controls (mean difference, 5.80 mm; 95% CI: 1.09, 10.52; p = .02). Patients with FS were less accurate (mean difference, 5.90%; 95% CI: 0.36, 11.43; p = .03) and slower (mean difference, -0.26 s; 95% CI: 0.06, 0.45; p = .01) responding to images of their affected shoulder compared to their unaffected shoulder. No associations were found between pain intensity and duration and either TPDT or laterality judgement.

CONCLUSIONS

Participants with FS demonstrated reduced tactile acuity and impaired laterality judgement over their affected shoulder compared to their unaffected shoulder. When compared to controls, subjects with FS showed reduced tactile acuity. TRIAL REGISTRATION CLINICALTRIALS.

GOV IDENTIFIER

NCT03320200.

GR Dimerization and the Impact of GR Dimerization on GR Protein Stability and Half-Life

Pharmacologically, glucocorticoids, which mediate their effects via the glucocorticoid receptor (GR), are a most effective therapy for inflammatory diseases despite the fact that chronic use causes side-effects and acquired GC resistance. The design of drugs with fewer side-effects and less potential for the development of resistance is therefore considered crucial for improved therapy. Dimerization of the GR is an integral step in glucocorticoid signaling and has been identified as a possible molecular site to target for drug development of anti-inflammatory drugs with an improved therapeutic index. Most of the current understanding regarding the role of GR dimerization in GC signaling derives for dimerization deficient mutants, although the role of ligands biased toward monomerization has also been described. Even though designing for loss of dimerization has mostly been applied for reduction of side-effect profile, designing for loss of dimerization may also be a fruitful strategy for the development of GC drugs with less potential to develop GC resistance. GC-induced resistance affects up to 30% of users and is due to a reduction in the GR functional pool. Several molecular mechanisms of GC-mediated reductions in GR pool have been described, one of which is the autologous down-regulation of GR density by the ubiquitin-proteasome-system (UPS). Loss of GR dimerization prevents autologous down-regulation of the receptor through modulation of interactions with components of the UPS and post-translational modifications (PTMs), such as phosphorylation, which prime the GR for degradation. Rational design of conformationally biased ligands that select for a monomeric GR conformation, which increases GC sensitivity through improving GR protein stability and increasing half-life, may be a productive avenue to explore. However, potential drawbacks to this approach should be considered as well as the advantages and disadvantages in chronic vs. acute treatment regimes.

Disease- and treatment-associated acquired glucocorticoid resistance

The development of resistance to glucocorticoids (GCs) in therapeutic regimens poses a major threat. Generally, GC resistance is congenital or acquired over time as a result of disease progression, prolonged GC treatment or, in some cases, both. Essentially, disruptions in the function and/or pool of the glucocorticoid receptor α (GRα) underlie this resistance. Many studies have detailed how alterations in GRα function lead to diminished GC sensitivity; however, the current review highlights the wealth of data concerning reductions in the GRα pool, mediated by disease-associated and treatment-associated effects, which contribute to a significant decrease in GC sensitivity. Additionally, the current understanding of the molecular mechanisms involved in driving reductions in the GRα pool is discussed. After highlighting the importance of maintaining the level of the GRα pool to combat GC resistance, we present current strategies and argue that future strategies to prevent GC resistance should involve biased ligands with a predisposition for reduced GR dimerization, a strategy originally proposed as the SEMOGRAM-SEDIGRAM concept to reduce the side-effect profile of GCs.

Chemoprevention of LA7-Induced Mammary Tumor Growth by SM6Met, a Well-Characterized Cyclopia Extract

Breast cancer (BC) is the leading cause of cancer-related deaths in women. Chemoprevention of BC by using plant extracts is gaining attention. SM6Met, a well-characterized extract of Cyclopia subternata with reported selective estrogen receptor subtype activity, has shown tumor suppressive effects in a chemically induced BC model in rats, which is known to be estrogen responsive. However, there is no information on the estrogen sensitivity of the relatively new orthotopic model of LA7 cell-induced mammary tumors. In the present study, the potential chemopreventative and side-effect profile of SM6Met on LA7 cell-induced tumor growth was evaluated, as was the effects of 17β-estradiol and standard-of-care (SOC) endocrine therapies, such as tamoxifen (TAM), letrozole (LET), and fulvestrant (FUL). Tumor growth was observed in the tumor-vehicle control group until day 10 post tumor induction, which declined afterward on days 12-14. SM6Met suppressed tumor growth to the same extent as TAM, while LET, but not FUL, also showed substantial anti-tumor effects. Short-term 17β-estradiol treatment reduced tumor volume on days prior to day 10, whereas tumor promoting effects were observed during long-term treatment, which was especially evident at later time points. Marked elevation in serum markers of liver injury, which was further supported by histological evaluation, was observed in the vehicle-treated tumor control, TAM, LET, and long-term 17β-estradiol treatment groups. Alterations in the lipid profiles were also observed in the 17β-estradiol treatment groups. In contrast, SM6Met did not augment the increase in serum levels of liver injury biomarkers caused by tumor induction and no effect was observed on lipid profiles. In summary, the results from the current study demonstrate the chemopreventative effect of SM6Met on mammary tumor growth, which was comparable to that of TAM, without eliciting the negative side-effects observed with this SOC endocrine therapy. Furthermore, the results of this study also showed some responsiveness of LA7-induced tumors to estrogen and SOC endocrine therapies. Thus, this model may be useful in evaluating potential endocrine therapies for hormone responsive BC.

The phytoestrogenic Cyclopia extract, SM6Met, increases median tumor free survival and reduces tumor mass and volume in chemically induced rat mammary gland carcinogenesis

SM6Met, a phytoestrogenic extract of Cyclopia subternata indigenous to the Western Cape province of South Africa, displays estrogenic attributes with potential for breast cancer chemoprevention. In this study, we report that SM6Met, in the presence of estradiol, induces a significant cell cycle G0/G1 phase arrest similar to the selective estrogen receptor modulator, tamoxifen. Furthermore, as a proof of concept, in the N-Methyl-N-nitrosourea induced rat mammary gland carcinogenesis model, SM6Met increases tumor latency by 7days and median tumor free survival by 42 days, while decreasing palpable tumor frequency by 32%, tumor mass by 40%, and tumor volume by 53%. Therefore, the current study provides proof of concept that SM6Met has definite potential as a chemopreventative agent against the development and progression of breast cancer.

Divide and Conquer May Not Be the Optimal Approach to Retain the Desirable Estrogenic Attributes of the Cyclopia Nutraceutical Extract, SM6Met

The genus Cyclopia, an indigenous South African fynbos plant used to prepare honeybush tea, contains phytoestrogenic compounds. An extract from C. subternata, SM6Met, displays three desirable estrogenic attributes for future development of a phytoestrogenic nutraceutical, namely, ERα antagonism, ERβ agonism, and also antagonism of E₂-induced breast cancer cell proliferation. Activity-guided fractionation of SM6Met was used in an attempt to isolate and identify compounds conferring the desirable estrogenic profile to SM6Met. Initial liquid-liquid fractionation of SM6Met yielded a polar fraction (PF) and a non-polar fraction (NPF), with the desirable estrogenic attributes retained in the NPF. Subsequent high performance counter-current chromatography (HPCCC) fractionation of the NPF yielded three fractions (F1-F3). Interestingly, the fractions revealed separation of the previously demonstrated positive estrogenic attributes of the NPF into separate fractions, with F1 and F2 acting as ERα antagonists, only F2 inducing antagonism of E₂-induced breast cancer cell proliferation and only F3 retaining robust ERβ agonist activity. In terms of major polyphenols, quantitative HPLC and liquid chromatography tandem mass spectrometry (LC-MS/MS) indicated that HPCCC fractionation resulted in a divergence of polyphenolic classes, with F1 emerging as the dihydrochalcone-rich fraction and F2 as the flavanone- and benzophenone-rich fraction, while the xanthones, flavones and phenolic acids were retained in F3. F3 was re-engineered into F3R by reassembling the major polyphenols identified in the fraction. F3R could, however, not replicate the effect of F3. In conclusion, although activity-guided fractionation results suggest that retention of all the desirable estrogenic attributes of the original SM6Met in one fraction is not an attainable goal, fractionation is a useful tool to enhance specific desirable estrogenic attributes.

Inhibition of corticosteroid-binding globulin gene expression by glucocorticoids involves C/EBPβ

Corticosteroid-binding globulin (CBG), a negative acute phase protein produced primarily in the liver, is responsible for the transport of glucocorticoids (GCs). It also modulates the bioavailability of GCs, as only free or unbound steroids are biologically active. Fluctuations in CBG levels therefore can directly affect GC bioavailability. This study investigates the molecular mechanism whereby GCs inhibit the expression of CBG. GCs regulate gene expression via the glucocorticoid receptor (GR), which either directly binds to DNA or acts indirectly via tethering to other DNA-bound transcription factors. Although no GC-response elements (GRE) are present in the Cbg promoter, putative binding sites for C/EBPβ, able to tether to the GR, as well as HNF3α involved in GR signaling, are present. C/EBPβ, but not HNF3α, was identified as an important mediator of DEX-mediated inhibition of Cbg promoter activity by using specific deletion and mutant promoter reporter constructs of Cbg. Furthermore, knockdown of C/EBPβ protein expression reduced DEX-induced repression of CBG mRNA, confirming C/EBPβ’s involvement in GC-mediated CBG repression. Chromatin immunoprecipitation (ChIP) after DEX treatment indicated increased co-recruitment of C/EBPβ and GR to the Cbg promoter, while C/EBPβ knockdown prevented GR recruitment. Together, the results suggest that DEX repression of CBG involves tethering of the GR to C/EBPβ.

Cyclopia extracts act as ERα antagonists and ERβ agonists, in vitro and in vivo

Hormone replacement therapy associated risks, and the concomitant reluctance of usage, has instigated the search for new generations of estrogen analogues that would maintain estrogen benefits without associated risks. Furthermore, if these analogues display chemo-preventative properties in breast and endometrial tissues it would be of great value. Both the selective estrogen receptor modulators as well as the selective estrogen receptor subtype modulators have been proposed as estrogen analogues with improved risk profiles. Phytoestrogen containing extracts of Cyclopia, an indigenous South African fynbos plant used to prepare Honeybush tea may serve as a source of new estrogen analogues. In this study three extracts, P104, SM6Met, and cup-of-tea, from two species of Cyclopia, C. genistoides and C. subternata, were evaluated for ER subtype specific agonism and antagonism both in transactivation and transrepression. For transactivation, the Cyclopia extracts displayed ERα antagonism and ERβ agonism when ER subtypes were expressed separately, however, when co-expressed only agonism was uniformly observed. In contrast, for transrepression, this uniform behavior was lost, with some extracts (P104) displaying uniform agonism, while others (SM6Met) displayed antagonism when subtypes were expressed separately and agonism when co-expressed. In addition, breast cancer cell proliferation assays indicate that extracts antagonize cell proliferation in the presence of estrogen at lower concentrations than that required for proliferation. Furthermore, lack of uterine growth and delayed vaginal opening in an immature rat uterotrophic model validates the ERα antagonism of extracts observed in vitro and supports the potential of the Cyclopia extracts as a source of estrogen analogues with a reduced risk profile.

Impact of glucocorticoid receptor density on ligand-independent dimerization, cooperative ligand-binding and basal priming of transactivation: a cell culture model

Glucocorticoid receptor (GR) levels vary between tissues and individuals and are altered by physiological and pharmacological effectors. However, the effects and implications of differences in GR concentration have not been fully elucidated. Using three statistically different GR concentrations in transiently transfected COS-1 cells, we demonstrate, using co-immunoprecipitation (CoIP) and fluorescent resonance energy transfer (FRET), that high levels of wild type GR (wtGR), but not of dimerization deficient GR (GRdim), display ligand-independent dimerization. Whole-cell saturation ligand-binding experiments furthermore establish that positive cooperative ligand-binding, with a concomitant increased ligand-binding affinity, is facilitated by ligand-independent dimerization at high concentrations of wtGR, but not GRdim. The down-stream consequences of ligand-independent dimerization at high concentrations of wtGR, but not GRdim, are shown to include basal priming of the system as witnessed by ligand-independent transactivation of both a GRE-containing promoter-reporter and the endogenous glucocorticoid (GC)-responsive gene, GILZ, as well as ligand-independent loading of GR onto the GILZ promoter. Pursuant to the basal priming of the system, addition of ligand results in a significantly greater modulation of transactivation potency than would be expected solely from the increase in ligand-binding affinity. Thus ligand-independent dimerization of the GR at high concentrations primes the system, through ligand-independent DNA loading and transactivation, which together with positive cooperative ligand-binding increases the potency of GR agonists and shifts the bio-character of partial GR agonists. Clearly GR-levels are a major factor in determining the sensitivity to GCs and a critical factor regulating transcriptional programs.

Phytoestrogenic potential of Cyclopia extracts and polyphenols

Cyclopia Vent. species, commonly known as honeybush, are endemic to Southern Africa. The plant is traditionally used as an herbal tea but several health benefits have recently been recorded. This minireview presents an overview of polyphenols found in Cyclopia and focuses on the phytoestrogenic potential of selected polyphenols and of extracts prepared from the plant.

Glucocorticoid receptor concentration and the ability to dimerize influence nuclear translocation and distribution

Glucocorticoid receptor (GR) concentrations and the ability of the GR to dimerize are factors which influence sensitivity to glucocorticoids. Upon glucocorticoid binding, the GR is actively transported into the nucleus, a crucial step in determining GR function. We examined the effects of GR concentration and the ability to dimerize on GR nuclear import, export and nuclear distribution using both live cell microscopy of GFP-tagged GR and immunofluorescence of untagged GR, with both wild type GR (GRwt) and dimerization deficient GR (GRdim). We found that the observed rate of GR nuclear import increases significantly at higher GR concentrations, at saturating concentrations of dexamethasone (10(-6) M) using GFP-tagged GR, while with untagged GR it is only discernable at sub-saturating ligand concentrations (10(-10)-10(-9) M). Loss of dimerization results in a slower observed rate of nuclear import (2.5- to 3.3-fold decrease for GFP-GRdim) as well as a decreased extent of GR nuclear localization (18-27% decrease for untagged GRdim). These results were linked to an increased rate of GR export at low GR concentrations (1.4- to 1.6-fold increase for untagged GR) and where GR dimerization is abrogated (1.5- to 1.7-fold increase for GFP-GRdim). Furthermore, GR dimerization was shown to be required for the appearance of discrete GC-dependent GR nuclear foci, the loss of which may explain the increased rate of GR export for the GRdim. The reduction in the observed rate of nuclear import and increased rate of nuclear export displayed at low GR concentrations and by the GRdim could explain the lowered glucocorticoid response under these conditions.

Approaches toward learning in physiotherapy

The aim of this study was to investigate the approaches toward learning of undergraduate Physiotherapy students in a PBl module to enhance facilitation of learning at the Stellenbosch University, Division of Physiotherapy in South Africa. This quantitative, descriptive study utilized the revised Two-factor Study Process Questionnaire (r-SPQ-2f) to evaluate the study cohorts’ approaches toward learning in the module. results of the data instruments were analysed statistically and discussed in a descriptive manner. There were a statistically significant greater number of students who adopted a deep approach toward learning at the commencement of the academic year. Students showed a trend toward an increase in their intrinsic interest in the learning material as the module progressed. Students in the Applied Physiotherapy module (ATP) started to shift their focus from a surface learning approach to a deep learning approach. further research is needed to determine the long-term changes in approach toward learning and the possible determinants of these changes. This can be done in conjunction with the implementation of quality assurance mechanisms for learning material and earlier preparation of students for the change in the learning environment.

Differential nuclear localisation and promoter occupancy play a role in glucocorticoid receptor ligand-specific transcriptional responses

The glucocorticoid receptor (GR) is a ligand-activated transcription factor for which a number of endogenous and synthetic ligands exist. A key question in steroid receptor biology is how different ligands elicit different maximal transcriptional responses via the same receptor and on the same promoter. This question was addressed quantitatively for the GR, using a panel of agonists, partial agonists and antagonists, on the endogenous GILZ gene in two different human cell lines. It was found that the extent of GR nuclear localization correlated with the efficacy for GILZ transactivation by the GR in U2OS cells. However, in A549 cells there was no significant correlation, with all ligands resulting in similar levels of GR nuclear localization, despite different levels of transcriptional activation of the GILZ gene. Chromatin immunoprecipitation analysis on the other hand, revealed ligand-specific differences in GILZ promoter occupancy in the A549 cells, which correlated with the transcriptional efficacy of the subset of ligands investigated. This suggests that ligand-specific differences in promoter occupancy by activated GR play a major role in discrimination between agonist, partial agonist and antagonist responses on the endogenous GILZ gene in A549 cells, while differences in nuclear localisation of liganded GR play a role in determining the transcriptional outcome in U2OS cells. These cell line-specific differences were not dependent on the amount of GR present, since transient overexpression of GR in U2OS did not alter the relative ligand-selective nuclear localisation. Our results show that there is a relationship between ligand-specific transactivation efficacy, extent of nuclear translocation and recruitment of GR to the promoter. However, the relative contribution of nuclear translocation and GR promoter recruitment to ligand-specific transactivation efficacy is cell-specific.

Interplay of the inflammatory and stress systems in a hepatic cell line: interactions between glucocorticoid receptor agonists and interleukin-6

The liver plays an important role in inflammation and stress by producing the acute phase proteins (APPs) required for resolution of inflammation as well as by delivering systemic glucose, through gluconeogenesis, required to fuel the stress response. Disruption of the interplay between interleukin 6 (IL-6) and glucocorticoids (GCs), the peripheral mediators of inflammation and stress, respectively, may lead to side-effects associated with the pharmacological use of GCs. The current study investigated the interplay between IL-6 and GCs in a hepatoma cell line (BWTG3) at protein (protein activity assays, Western blotting, and ELISA) and mRNA (qPCR) levels. Specifically, the action of dexamethasone (Dex), a known antiinflammatory drug and glucocorticoid receptor (GR) agonist, is compared to that of Compound A (CpdA), a selective glucocorticoid receptor agonist (SEGRA). CpdA, like IL-6, but unlike Dex, increases GR binding and decreases the metabolic enzymes, tyrosine aminotransferase, phosphoenolpyruvate carboxykinase, and gamma glutamyltransferase, at protein or mRNA level. Like Dex, both CpdA and IL-6 increase the positive APPs, serum amyloid A and C-reactive protein, and decrease the negative APP, corticosteroid binding globulin. The study shows that the GC, Dex, and IL-6 generally have divergent effects on the GR and metabolic enzymes, while their functions are convergent on the APPs. In contrast to Dex, CpdA has effects convergent to that of IL-6 on the GR, metabolic enzymes, and APPs. Thus these findings suggest that CpdA, like Dex, modulates APPs, leading to effective control of inflammation, while, in contrast to Dex, it is less likely to lead to GC-induced side-effects.

Role of ligand-dependent GR phosphorylation and half-life in determination of ligand-specific transcriptional activity

A central question in glucocorticoid mechanism of action via the glucocorticoid receptor (GR) is what determines ligand-selective transcriptional responses. Using a panel of 12 GR ligands, we show that the extent of GR phosphorylation at S226 and S211, GR half-life and transcriptional response, occur in a ligand-selective manner. While GR phosphorylation at S226 was shown to inhibit maximal transcription efficacy, phosphorylation at S211 is required for maximal transactivation, but not for transrepression efficacy. Both ligand-selective GR phosphorylation and half-life correlated with efficacy for transactivation and transrepression. For both expressed and endogenous GR, in two different cell lines, agonists resulted in the greatest extent of phosphorylation and the greatest extent of GR downregulation, suggesting a link between these functions. However, using phosphorylation-deficient GR mutants we established that phosphorylation of the GR at S226 or S211 does not determine the rank order of ligand-selective GR transactivation. These results are consistent with a model whereby ligand-selective GR phosphorylation and half-life are a consequence of upstream events, such as ligand-specific GR conformations, which are maintained in the phosphorylation mutants.

Abrogation of glucocorticoid receptor dimerization correlates with dissociated glucocorticoid behavior of compound a

Compound A (CpdA), a dissociated glucocorticoid receptor modulator, decreases corticosteroid-binding globulin (CBG), adrenocorticotropic hormone (ACTH), and luteneinizing hormone levels in rats. Whether this is due to transcriptional regulation by CpdA is not known. Using promoter reporter assays we show that CpdA, like dexamethasone (Dex), directly transrepresses these genes. Results using a rat Cbg proximal-promoter reporter construct in BWTG3 and HepG2 cell lines support a glucocorticoid receptor (GR)-dependent transrepression mechanism for CpdA. However, CpdA, unlike Dex, does not result in transactivation via glucocorticoid-responsive elements within a promoter reporter construct even when GR is co-transfected. The inability of CpdA to result in transactivation via glucocorticoid-responsive elements is confirmed on the endogenous tyrosine aminotransferase gene, whereas transrepression ability is confirmed on the endogenous CBG gene. Consistent with a role for CpdA in modulating GR activity, whole cell binding assays revealed that CpdA binds reversibly to the GR, but with lower affinity than Dex, and influences association of [(3)H]Dex, but has no effect on dissociation. In addition, like Dex, CpdA causes nuclear translocation of the GR, albeit to a lesser degree. Several lines of evidence, including fluorescence resonance energy transfer, co-immunoprecipitation, and nuclear immunofluorescence studies of nuclear localization-deficient GR show that CpdA, unlike Dex, does not elicit ligand-induced GR dimerization. Comparison of the behavior of CpdA in the presence of wild type GR to that of Dex with a dimerization-deficient GR mutant (GR(dim)) strongly supports the conclusion that loss of dimerization is responsible for the dissociated behavior of CpdA.

Functional analysis of the 5' regulatory region of the 5-aminolevulinate synthase (ALAS1) gene in response to estrogen

Genetic defects in the heme synthesis enzymes lead to a group of heterogeneous disorders termed the porphyrias. Numerous factors influence the clinical expression of porphyrias, primarily by altering the rate of heme synthesis. To date, no genotype-phenotype correlation has been made to explain the variable penetrance observed in variegate porphyria (VP) and other acute hepatic porphyrias. As first and rate determining gene in the heme pathway, 5-aminolevulinate synthase-1 (ALAS1), appears to be an ideal candidate modifier. Previous studies established critical mechanisms for ALAS1 regulation and a direct transcriptional response to drugs by defined drug-responsive enhancer sequences (ADRES). To identify possible functional variants within the 5' region of ALAS1, selected regulatory regions, including the ADRES elements, were screened by DNA sequencing analysis in 26 VP patients heterozygous for the causative R59W mutation in the protoporphyrinogen oxidase (PPOX) gene. Two novel variants, -853C>T and -1253T>A were identified. In silico analyses indicated that the -853C>T transition is located immediately 5' to a half-palindromic putative estrogen receptor binding site. Co-transfection experiments with an estrogen receptor-alpha (ERalpha) expression vector in HepG2 cells, suggest that this region mediates an increased transcriptional response in the presence of estrogen (E2) and ERalpha. The wild-type -853C/-1253T allele induced a 47% increase in transcription, while the -853T/-1253A double mutant allele showed a 35% increase in transcription compared to expression in the absence of E2. The highest induction was observed for the mutant -853T/1253T allele that generated an increase of 66%. We conclude that the -853T variant functions as an enhancer in the presence of estrogen and speculates that the -1253A variant reduces transcription activity.

Ligand-selective transactivation and transrepression via the glucocorticoid receptor: role of cofactor interaction

The mechanisms that determine ligand-selective transcriptional responses by the glucocorticoid receptor (GR) are not fully understood. Using a wide panel of GR ligands, we investigated the relationships between the potency and maximal response for transactivation via a glucocorticoid response element (GRE) and transrepression via both nuclear factor small ka, CyrillicB (NFsmall ka, CyrillicB) and activator protein-1 (AP-1) sites, relative binding affinity for the GR, as well as interaction with both coactivators and corepressors. The results showed ligand-selective differences in potency and efficacy for each promoter, as well as for a particular ligand between the three promoters. Ligand potency correlated with relative affinity for the GR for agonists and partial agonists in transactivation but not for transrepression. Maximal response was unrelated to relative affinity of ligand for GR for both transactivation and transrepression. A good and significant correlation between full length coactivator binding in two-hybrid assays and efficacy as well as potency of different receptor-steroid complexes for both transactivation and transrepression supports a major role for coactivator recruitment in determination of ligand-selective transcriptional activity. Furthermore, ligand-selective GR binding to GRIP-1, as determined by both two-hybrid and DNA pull down assays, correlated positively with ligand-selective efficacy for transactivation of both a synthetic GRE reporter with expressed GR as well as of an endogenous gene via endogenous GR. The receptor interacting domain of the corepressor SMRT exhibited strong interaction with both agonists and partial agonists, similar to the results for coactivators, suggesting a possible role for SMRT in activation of transcription. However, there was no correlation between ligand affinity for the GR and cofactor interaction. These results provide strong quantitative biochemical support for a model in which GR-mediated ligand-selective differential interaction with GRIP-1, SRC-1A, NCoR and SMRT is a major determinant of ligand-selective and promoter-specific differences in potency and efficacy, for both transactivation and transrepression.

Preoperative education for lumbar surgery for radiculopathy

To date no studies have been published on preoperative education forpatients who had lumbar surgery. The aim of this study was to determine if there is a demand for preoperative education for patients who had lumbar surgery for radiculopathy. A convenience sample of 47 patients who had lumbar surgery and a random sample of 141 physiotherapists involved in treating patients who had lumbar surgery completed a newly developed spinal surgery questionnaire. The data were analyzed using descriptiveand inferential statistical tests. Results showed that 100% of the patients and 99% of therapists view preoperative education to be an important component for lumbar surgery for radiculopathy. The most important factors identifiedfor inclusion in preoperative educational programs were reason for surgery, risks associated with surgery, limitations following surgery and more education regarding pain. The preferred method of education delivery was verbal one-on-one education. This study demonstrates that there is a demand for preoperative education for patients who had lumbar surgery.

Selective extraction of Cyclopia for enhanced in vitro phytoestrogenicity and benchmarking against commercial phytoestrogen extracts

Previous work established the phytoestrogenicity of "unfermented"Cyclopia (honeybush) extracts. The current study investigated the phytoestrogenicity of four Cyclopia harvestings (M6-9) for preparation of extracts with enhanced phytoestrogenicity for benchmarking against commercial preparations. Two extracts, from M6 (C. subternata) and M7 (C. genistoides), were identified as most phytoestrogenic using estrogen receptor binding, an estrogen receptor response element containing promoter reporter assay, alkaline phosphatase activity, and E-screen. M6 and M7 were sequentially and non-sequentially extracted with five solvents of differing polarities. Additionally, two extracts were prepared in the traditional way of preparing a cup of honeybush tea. The resultant 22 extracts were evaluated for estrogenicity. Select extracts were analysed by high-pressure liquid chromatography (HPLC) and liquid chromatography mass spectrometry (LC-MS). The sequentially extracted M6 methanol extract (SM6Met) had the highest potency and the sequentially extracted M6 ethyl acetate extract (SM6EAc) had the highest efficacy of all the extracts. The HPLC results suggested enrichment of luteolin in SM6EAc and enrichment of an unidentified polyphenol in SM6Met. Benchmarking against four commercial phytoestrogenic preparations suggest that in terms of the assays used, Cyclopia extracts have comparable potency and efficacy to the commercial extracts and thus have potential as marketable phytoestrogenic nutraceuticals.

South African herbal teas: Aspalathus linearis, Cyclopia spp. and Athrixia phylicoides--a review

Rooibos (Aspalathus linearis (Brum.f) Dahlg.) and honeybush (Cyclopia Vent. species) are popular indigenous South African herbal teas enjoyed for their taste and aroma. Traditional medicinal uses of rooibos in South Africa include alleviation of infantile colic, allergies, asthma and dermatological problems, while a decoction of honeybush was used as a restorative and as an expectorant in chronic catarrh and pulmonary tuberculosis. Traditional medicinal uses of Athrixia phylicoides DC., or bush tea, another indigenous South African plant with very limited localised use as herbal tea, include treatment of boils, acne, infected wounds and infected throats. Currently rooibos and honeybush are produced for the herbal tea market, while bush tea has potential for commercialisation. A summary of the historical and modern uses, botany, distribution, industry and chemical composition of these herbal teas is presented. A comprehensive discussion of in vitro, ex vivo and in vivo biological properties, required to expand their applications as nutraceutical and cosmeceutical products, is included, with the main emphasis on rooibos. Future research needs include more comprehensive chemical characterisation of extracts, identification of marker compounds for extract standardisation and quality control, bioavailability and identification of bio-markers of dietary exposure, investigation of possible herb-drug interactions and plant improvement with regards to composition and bioactivity.

Perceptions, expectations, apprehensions and realities of graduating South African optometry students (PEAR study, 2006)

The objective of this study was to establish the perceptions, expectations, apprehensions and realities of South Africa optometry students completing their undergraduate studies in 2006. Copies of a questionnaire containing relevant information were distributed to all graduating students at the four Universities offering Optometry. The responses were coded and analyzed. The respondents (N=143), representing 77% of the graduating students included 27.3% males and 72.7% females, aged 20 to 37 years (mean = 23.34 ± 2.75). About a third (32.9%) of the respondents considered opening their own practice as the best way of entering into practice. Also, this mode of practice was considered as providing the greatest fulfilment for their personal (60.8%) and professional (53.8%) goals as well as offering long  term financial security (43.7%). Many (56.6%) have secured employment before graduation. Upon graduation, 43.4% would like to join a franchise.  Many (79.7%) felt that Government was not offering sufficient opportunities for optometrists. The majority, (70.6%) felt that the South African optometry profession is fastly becoming saturated and this was of great concern to many (31.5%). About half, (50.3%) have plans to go overseas to practice and the most common destinations were the UK (36.1%) and Australia (15%).  The mean minimum monthly salary expected as new graduates was between R9 500 and R11 500 in the public and private sectors respectively. On a response scale, the future of optometry in South Africa was scored as 6.59 ± 1.92. Findings in this study may be useful to all stake holders in optometric education in South Africa, as they may reflect the future of the optometry profession in the country.

Evaluation of the phytoestrogenic activity of Cyclopia genistoides (honeybush) methanol extracts and relevant polyphenols

Unfermented C. genistoides methanol extracts of different harvestings and selected polyphenols were evaluated for phytoestrogenic activity by comparing binding to both ER subtypes, transactivation of an ERE-containing promoter reporter, proliferation of MCF-7-BUS and MDA-MB-231 breast cancer cells, and binding to SHBG. The extracts from one harvesting of C. genistoides (P104) bound to both ER subtypes. All extracts transactivated ERE-containing promoter reporters via ERbeta but not via ERalpha. All extracts, except P122, caused proliferation of the estrogen-sensitive MCF-7-BUS cells. Proliferation of MCF-7-BUS cells was ER-dependent as ICI 182,780 reversed proliferation. Physiologically more relevant, extracts antagonized E2-induced MCF-7-BUS cell proliferation. Furthermore, all extracts, except P122, induced proliferation of the estrogen-insensitive MDA-MB-231 cells, suggesting that the extracts are able to induce ER-dependent and ER-independent cell proliferation. Binding to SHBG by extracts was also demonstrated. These results clearly show that C. genistoides methanol extracts display phytoestrogenic activity and act predominantly via ERbeta. HPLC and LC-MS analysis, however, suggests that the observed phytoestrogenic activity cannot be ascribed to polyphenols known to be present in other Cyclopia species.

Illuminating the interrelated immune and endocrine adaptations after multiple exposures to short immobilization stress by in vivo blocking of IL-6

Intermittent psychological stress was induced in adult rats by 2 h/day of immobilization stress for 4 days, with or without blocking the function of IL-6 by using an anti-IL-6 antibody. Basal concentrations of serum corticosterone, IL-1β, IL-6, and TNF-α were assessed 24 h after the last intervention, as were levels of glucocorticoid receptors (GR) and activities of glucocorticoid-inducible enzymes (tyrosine aminotransferase and glutamine synthetase) in muscle and liver. Whole blood cultures were used to assess both spontaneous and LPS-induced reactivity of peripheral blood mononuclear cells. Stress increased corticosterone concentration in a manner partially modulated by IL-6. Serum IL-1β concentration was downregulated during stress when IL-6 was blocked ( P < 0.01). LPS-induced IL-6 secretion by peripheral blood mononuclear cells in vitro correlated positively with serum IL-1β concentration in antibody-treated groups, independently of stress ( R = 0.70 in nonstressed and R = 0.78 in stressed rats; both P < 0.05), whereas serum corticosterone concentration correlated positively with LPS-induced secretion of IL-6 only in control rats ( R = 0.66; P < 0.05). Reductions in liver GR levels indicated independent effects of stress (34.5%) and anti-IL-6 antibody (16.7%) and additive effects for both (62.5%). Similar results are reported for vastus muscle. Conversely, stress increased tyrosine aminotransferase and glutamine synthetase activities in muscle and liver with a significant ( P < 0.05) effect of anti-IL-6 antibody only seen in stressed livers. In conclusion, IL-6 plays a role in maintaining circulating IL-1β concentration after multiple exposures to stress, thus promoting a continued elevation of corticosterone release; in peripheral tissues, IL-6 antagonizes the effects of glucocorticoids, especially at the level of GR concentration.

Perceptions, expectations, apprehensions and realities of graduating South African optometry students (PEAR study, 2006)

The objective of this study was to establish the perceptions, expectations, apprehensions and realities of South Africa optometry students completing their undergraduate studies in 2006. Copies of a questionnaire containing relevant information were distributed to all graduating students at the four Universities offering Optometry. The responses were coded and analyzed. The respondents (N=143), representing 77% of the graduating students included 27.3% males and 72.7% females, aged 20 to 37 years (mean = 23.34 ± 2.75). About a third (32.9%) of the respondents considered opening their own practice as the best way of entering into practice. Also, this mode of practice was considered as providing the greatest fulfilment for their personal (60.8%) and professional (53.8%) goals as well as offering long  term financial security (43.7%). Many (56.6%) have secured employment before graduation. Upon graduation, 43.4% would like to join a franchise.  Many (79.7%) felt that Government was not offering sufficient opportunities for optometrists. The majority, (70.6%) felt that the South African optometry profession is fastly becoming saturated and this was of great concern to many (31.5%). About half, (50.3%) have plans to go overseas to practice and the most common destinations were the UK (36.1%) and Australia (15%).  The mean minimum monthly salary expected as new graduates was between R9 500 and R11 500 in the public and private sectors respectively. On a response scale, the future of optometry in South Africa was scored as 6.59 ± 1.92. Findings in this study may be useful to all stake holders in optometric education in South Africa, as they may reflect the future of the optometry profession in the country.

A fully dissociated compound of plant origin for inflammatory gene repression

The identification of selective glucocorticoid receptor (GR) modifiers, which separate transactivation and transrepression properties, represents an important research goal for steroid pharmacology. Although the gene-activating properties of GR are mainly associated with undesirable side effects, its negative interference with the activity of transcription factors, such as NF-kappaB, greatly contributes to its antiinflammatory and immune-suppressive capacities. In the present study, we found that Compound A (CpdA), a plant-derived phenyl aziridine precursor, although not belonging to the steroidal class of GR-binding ligands, does mediate gene-inhibitory effects by activating GR. We demonstrate that CpdA exerts an antiinflammatory potential by down-modulating TNF-induced proinflammatory gene expression, such as IL-6 and E-selectin, but, interestingly, does not at all enhance glucocorticoid response element-driven genes or induce GR binding to glucocorticoid response element-dependent genes in vivo. We further show that the specific gene-repressive effect of CpdA depends on the presence of functional GR, displaying a differential phosphorylation status with CpdA as compared with dexamethasone treatment. The antiinflammatory mechanism involves both a reduction of the in vivo DNA-binding activity of p65 as well as an interference with the transactivation potential of NF-kappaB. Finally, we present evidence that CpdA is as effective as dexamethasone in counteracting acute inflammation in vivo and does not cause a hyperglycemic side effect. Taken together, this compound may be a lead compound of a class of antiinflammatory agents with fully dissociated properties and might thus hold great potential for therapeutic use.

Synthetic progestins used in HRT have different glucocorticoid agonist properties

The synthetic progestins, medroxyprogesterone acetate (MPA) and norethisterone acetate (NET-EN or NET-A), are widely used as female contraceptive agents and in hormone replacement therapy (HRT). Competitive binding revealed that MPA displays a higher relative binding affinity than NET-A and progesterone (prog) for the human GR (Kd of 4.2 nM for dexamethasone (dex) and Ki's of 10.8, 270 and 215 nM for MPA, NET-A and prog, respectively). Furthermore, MPA displays much greater glucocorticoid (GC) transactivation agonist potency than NET-A or prog (EC50s of 1.1, 7.2, >1000 and 280 nM for dex, MPA, NET-A and prog, respectively) and much greater GC agonist potency for transrepression than NET-A or prog (EC50s of 0.21, 2.7, >100 and 26 nM for dex, MPA, NET-A and prog, respectively). In addition, MPA induces phosphorylation of the GR at Ser 211 to a much greater extent than NET-A or prog and protects the GR from partial trypsin digestion in vitro to a much greater extent than NET-A or prog at saturating concentrations. Together these results suggest that the differences in biological activity of the progestins are not merely due to differences in their affinity for the GR but also due to the induction of different conformational changes in the liganded-GR. MPA and NET-A therefore display very different GC-like properties compared to each other and to prog, and are likely to exhibit different side effects via the GR.

Not all progestins are the same: implications for usage

Recent clinical evidence showing unexpected side-effects of progestins used in contraception and hormone replacement therapy has highlighted the importance of choice of synthetic progestin. The molecular mechanisms of action of the relatively nonspecific and most widely used synthetic progestins, medroxyprogesterone acetate and norethisterone, are discussed in the context of this recent clinical evidence. Future directions involving a more mechanism-based approach for improved therapeutics, with greater specificity and fewer side-effects, are discussed.

Biological activities of the shrub Salsola tuberculatiformis Botsch.: contraceptive or stress alleviator?

Plants belonging to the genus Salsola (Family: Chenopodiaceae) are common in the arid and semiarid regions of our planet with no less than 69 different Salsola species found in Namibia and the Republic of South Africa. This genus is used as a traditional medicine and aqueous extracts of Salsola have been used by Bushmen women as an oral contraceptive. Ingestion of the Namibian shrub Salsola tuberculatiformis Botsch. by pregnant Karakul sheep leads to prolonged gestation and fetal post-maturity and, as a result, the pelts of the new-born karakul lambs are worthless. This initiated an investigation into the active agents in the plant, using the terminal enzyme in adrenal corticosteroidogenesis, cytochrome P450-dependent 11beta-hydroxylase (P450c11), as a bioassay. Although the active fraction, S2, was extremely labile, partial structure determination suggested the presence of synephrine and a highly reactive aziridine. Therefore a more stable analogue, 2-(4-acetoxyphenyl)2-chloro-N-methylethylammonium-chloride (compound A), was synthesised, which, like the active plant extracts, inhibited adrenal steroidogenesis and acted as a contraceptive. In addition, compound A was stabilised by interaction with steroid-binding globulins in plasma thus enhancing biological activity in vivo. These findings provided explanations for the complex biological effects of the shrub as well as a new insight into the mode of action of chemically labile plant products in vivo.

Anti-androgenic properties of Compound A, an analog of a non-steroidal plant compound

We investigated the interactions between Compound A (CpdA), an analog of a hydroxyphenyl aziridine precursor found in an African shrub, and the androgen receptor (AR). CpdA represses androgen-induced activation of both specific and non-specific androgen DNA response elements. While a similar effect was obtained for the progesterone receptor (PR) via a non-specific hormone response element, CpdA had no effect on the actions of the glucocorticoid and mineralocorticoid receptors. CpdA represses the ligand-dependent interaction between the NH(2)- and COOH-terminal domains of the AR, similar to well-characterised anti-androgens. CpdA also interferes with the interaction of steroid receptor co-activator 1 (SRC1) with the activation domain AF2 but not with AF1. However, CpdA does not compete with androgen for binding to the AR. These results demonstrate that CpdA elicits anti-androgenic actions by a mechanism other than competitive binding for the AR.

Laparoscopic treatment of an isolated gallbladder rupture following blunt abdominal trauma in a schoolboy rugby player

Laparoscopic treatment of an isolated gallbladder rupture in a schoolboy rugby player resulting from blunt abdominal trauma has not previously been reported. A case report of this rare occurrence is presented together with a brief review of the literature.

Inhibition of cytochrome P450c11 by biogenic amines and an aziridine precursor, 2-(4-acetoxyphenyl)-2-chloro-N-methyl-ethylammonium chloride

The interaction of several biogenic amines and Compound A (2-(4-acetoxyphenyl)-2-chloro- N-methyl-ethylammonium chloride), an analogue of the active substance in a HPLC fraction isolated from the shrub, Salsola tuberculatiformis Botsch., with cytochrome P450c11 was investigated. Noradrenaline, octopamine and Compound A inhibited the type I DOC induced difference spectrum of P450c11 and elicited a type II difference spectrum when added alone. The Ks-values for noradrenaline, octopamine, and Compound A were 0.8 mM, 0.16 mM and 0.36 mM, respectively. Dopamine, adrenaline and synephrine did not interact with, or inhibit, P450c11. Further investigation of Compound A indicated that it is a mixed inhibitor of sheep P450c11 with a stronger competitive (Kic = 106-110 microM) than uncompetitive (Kiu = 667-737 microM) element, and that it inhibits the conversion of deoxycorticosterone to corticosterone by human 11beta-hydroxylase and aldosterone synthase with EC50 values of 97 microM and 190 microM, respectively, in fetal calf serum.

Twice weekly vs. daily chemotherapy for childhood tuberculosis

BACKGROUND

Treating childhood tuberculosis places a large burden on health services, and ways of lessening this were sought.

METHODS

A randomized controlled trial was conducted to determine the effectiveness of fully intermittent twice weekly treatment for intrathoracic childhood tuberculosis and its effect on adherence to treatment, in comparison with daily (weekday) treatment. The setting was a district of Cape Town, South Africa, an area of high incident tuberculosis. We randomized 206 children with confirmed (4%), probable (94%) and suspected (2%) intrathoracic tuberculosis: 89 (median age, 25 months) received intermittent treatment; and 117 (median age, 28 months) received daily treatment. Intermittent treatment (twice weekly for 6 months) was isoniazid 15 mg/kg/dose, rifampin 15 mg/kg/dose and pyrazinamide 55 mg/kg/dose for 2 months, followed by isoniazid and rifampin only for 4 months. Daily treatment was isoniazid 10 mg/kg/day, rifampin 10 mg/kg/day and pyrazinamide 25 mg/kg/day on weekdays for 6 months.

RESULTS

At 6 months 97% of subjects were discharged, with treatment outcomes in the two groups equivalent at that time (P = 0.90) and at the 18- to 30-month follow-up. One relapse occurred in the twice weekly group (P = 0.25). Adherence was equivalent; 70 children (79%) on intermittent and 90 (77%) on daily treatment took 75% or more of the prescribed doses (P = 0.90). Nonadherence over the full course of therapy was significantly associated with nonadherence during the first month of treatment (P = 0.0002) and household crowding (P = 0.002).

CONCLUSIONS

Six month fully intermittent antituberculosis treatment is an effective and acceptable alternative to daily treatment.

Investigation of the primary cause of hypoadrenocorticism in South African angora goats (Capra aegagrus): a comparison with Boer goats (Capra hircus) and Merino sheep (Ovis aries)

Our objective was to identify the primary site of the reduced adrenal function in South African Angora goats (Capra aegagrus) that causes a decrease in cortisol production and leads to severe losses of Angora goats during cold spells. Angora goats, Boer goats (Capra hircus), and Merino sheep (Ovis aries) were assigned to three intravenous treatments: 1) insulin, 2) corticotropin-releasing factor (CRF), and 3) ACTH. Blood cortisol concentrations were determined over a 90-min period to determine any differences in the response of the experimental animals to these treatments. For both the insulin and ACTH treatments, cortisol concentrations were less in Angora goats than in the other experimental animals. The adrenal gland was subsequently investigated as a possible cause for the observed hypoadrenocorticism. Primary adrenal cell cultures were prepared from these species, subjected to different treatments, and the cortisol production determined. Upon pregnenolone (PREG) addition, all the experimental animals' cortisol production increased significantly, with the production in Boer goats higher (P<.01) when compared with that in the other species. The stimulation of cortisol biosynthesis by ACTH was only obtained for Boer goats and Merino sheep. The stimulation of cortisol production by forskolin and cholera toxin were compared with ACTH, and, for Angora goats, only cholera toxin caused a significant increase in cortisol production. For Boer goats, no difference (P>.05) between the PREG, ACTH, forskolin, or cholera toxin treatments were observed. The Merino adrenal cells were increasingly stimulated in the following order: PREG, ACTH, forskolin, and cholera toxin (forskolin and cholera toxin stimulated cortisol production to the same extent). This investigation of the hypothalamic-pituitary-adrenocortical axis, therefore, identified the adrenal gland as the primary site of the Angora's hypoadrenocorticism.

Influence of an aziridine precursor on the in vitro binding parameters of rat and ovine corticosteroid-binding globulin (CBG)

Aziridines are highly reactive alkylating compounds used in cancer treatment. Salsola tuberculatiformis Botsch., which causes prolonged gestation in sheep and contraception in rats, contains a very labile hydroxy-phenylaziridine or its precursor. A less labile analogue, 2-(4-acetoxyphenyl)-2-chloro-N-methyl-ethylammonium chloride (Compound I), was synthesized and has been shown to be contraceptive in rats and to be stabilized by corticosteroid-binding globulin (CBG). The current study compared the binding parameters of rat and ovine CBG and evaluated the effect of the aziridine precursor, Compound I, on these parameters. Kd and Bmax values of 0.646 and 578 nM for corticosterone binding to rat CBG and 0.577 and 19.8 nM for cortisol binding to sheep CBG, respectively, were measured. In competitive binding studies with rat plasma, Ki values of 3.48 nM, 0.856 nM, 22.2 nM, 722 microM, and > 1,000,000 microM for cortisol, corticosterone, progesterone, Compound I, and synephrine (Compound II), respectively, were found, while in sheep plasma the values were 0.409 nM, 1.78 nM, 5.28 nM, 594 microM, and > 1,000,000 microM, respectively. Concentrations of Compound I equivalent to an effective pharmacological dose resulted in a significant (P < 0.01) decrease in CBG bound corticosterone and a significant (P < 0.01) increase in free corticosterone in rat plasma. In sheep, a similar effect was observed with cortisol. Progesterone binding, however, did not appear to be affected significantly by Compound I in either rat or sheep plasma. Compound I was found to be a competitive inhibitor of glucocorticoid binding to CBG. These results suggest that binding of Compound I to CBG with concomitant displacement of endogenous glucocorticoids, but not progesterone, may be part of the mechanism of action of these phenylaziridine compounds.

Salsola tuberculatiformis Botschantzev and an aziridine precursor analog mediate the in vivo increase in free corticosterone and decrease in corticosteroid-binding globulin in female Wistar rats

Salsola tuberculatiformis Botschantzev causes prolonged gestation in sheep and contraception in rats. An active fraction isolated from the shrub, containing a highly labile hydoxyphenyl aziridine or precursor, and a more stable analog, compound A, inhibits sheep adrenal cytochrome P450c11. In addition, compound A has been shown to bind to and be stabilized by corticosteroid-binding globulin (CBG). Binding may result in concomitant displacement of endogenous steroids, which could contribute to the biological effects of these compounds. The present study was undertaken to establish which mechanism would predominate in female rats. Compound A significantly (P < 0.01) displaced glucocorticoids, but not progesterone, from rat CBG in vitro, whereas in vivo the percentage of free plasma corticosterone in both S. tuberculatiformis (P < 0.05)- and compound A (P < 0.01)-treated rats was also significantly higher due to displacement from CBG. In addition, both ACTH and CBG concentrations were significantly (P < 0.05) lower than control values. The levels of the gonadotropins were also reduced during treatment, but only LH values significantly (P < 0.05) so. These results suggest that binding of the test substances to CBG in female rat plasma and concomitant displacement of endogenous corticosterone could be part of the contraceptive mechanism of S. tuberculatiformis and the aziridine precursor, compound A.

Mechanism for the stabilization in vivo of the aziridine precursor --(4-acetoxyphenyl)-2-chloro-N-methyl-ethylammonium chloride by serum proteins

Oral and intraperitoneal administration of 2-(4-acetoxyphenyl)-2-chloro-N-methyl-ethylammonium chloride (Compound A), an analogue of phenyl aziridine precursors that occur in the shrub Salsola tuberculatiformis Botsch, had a contraceptive effect on female Wistar rats with a concomitant decrease in total body, uterus, and every mass and an increase in abronal mass. Compound A elicited a Type II difference spectrum and inhibited the Type I deoxycorticosterone (DOC) induced difference spectrum of sheep adrenal cytochrome P450c11 in a manner similar to that of S2, a biologically active fraction isolated from S. tuberculatiformis. The effects of Compound A on the spectral properties of P450c11 were diminished with time in PBS. Electrospray mass spectrometry (ES-MS) indicated that the rate of cyclization of Compound A to the corresponding aziridine followed a time course similar to the attenuation of cytochrome P450c11 inhibition. It was concluded that the aziridine precursor. Compound A, rather than aziridine itself, was the inhibiting agent of sheep adrenal P450c11. Addition of sheep and rat plasma prevented the attenuation of the effect of Compound A on the spectral properties of cytochrome P450c11. Subsequent ES-MS analysis indicated that Compound A was stabilized in plasma by sex hormone binding globulin and corticosteroid binding globulin. These results suggest a mechanism whereby natural plant products, which are highly reactive and unstable in vitro, can be stabilized by binding to plasma proteins, and so remain biologically active in vivo.