Ischaemic stroke with multi-focal venous and arterial thrombosis due to hyperhomocysteinemia: anabolic androgenic steroid use and MTHFR c.667 C > T variant - a case report.

BACKGROUND: Severely elevated serum homocysteine is a rare cause of ischaemic stroke and extra-cranial arterial and venous thrombosis. Several factors can lead to mild elevation of homocysteine including dietary folate and B12 deficiency, and genetic variants of the methylenetetrahydrofolate reductase (MTHFR) enzyme. The use of Anabolic androgenic steroid (AAS) is under-reported, but increasingly linked to ischaemic stroke and can raise homocysteine levels. CASE REPORT: We present a case of a man in his 40s with a large left middle cerebral artery (MCA) territory ischaemic stroke and combined multifocal, extracranial venous, and arterial thrombosis. His past medical history was significant for Crohn's disease and covert use of AAS. A young stroke screen was negative except for a severely elevated total homocysteine concentration, folate and B12 deficiencies. Further tests revealed he was homozygous for the methylenetetrahydrofolate reductase enzyme thermolabile variant (MTHFR c.667 C > T). The etiology of this stroke was a hypercoagulable state induced by raised plasma homocysteine. Raised homocysteine in this case was likely multifactorial and related to chronic AAS use in combination with the homozygous MTHFR c.677 C > T thermolabile variant, folate deficiency and, vitamin B12 deficiency. CONCLUSION: In summary, hyperhomocysteinemia is an important potential cause of ischaemic stroke and may result from genetic, dietary, and social factors. Anabolic androgenic steroid use is an important risk factor for clinicians to consider, particularly in cases of young stroke with elevated serum homocysteine. Testing for MFTHR variants in stroke patients with raised homocysteine may be useful to guide secondary stroke prevention through adequate vitamin supplementation. Further studies looking into primary and secondary stroke prevention in the high-risk MTHFR variant cohort are necessary.

Impact of preimplantation genetic testing for aneuploidies (PGT-A) on first trimester biochemical markers - PAPP-A (placenta-associated plasma protein) and free ß-hCG (human chorionic gonadotropin).

OBJECTIVE: The objective of the study was to study the effect of preimplantation genetic testing for aneuploidies (PGT-A) performed at blastocyst stage on the levels of first trimester biomarkers. METHODS: This is an observational, collaborative, retrospective study. Seven hundred and twenty-eight patients were included in the study. Patients were with singleton pregnancies resulting from either natural conception (NC), or assisted reproductive techniques (ARTs) with PGT-A and frozen embryo transfer (FET) (ART/PGT-A/FET) or after ART without PGT-A and fresh ET (ART/no PGT-A/fresh ET) or FET (ART/no PGT-A/FET), who had first trimester combined screening test between 11 and 14 gestational weeks. They were stratified into four groups: group A (ART/PGT-A/FET) - 143 patients; group B (ART/no PGT-A/FET) - 100 patients; group C (ART/no PGT-A/fresh ET) - 346 patients, and group D (NC) - 139 patients. RESULTS: Statistically significant differences among the examined groups were observed for maternal age, BMI, ethnicity, and parity. The median placenta-associated plasma protein (PAPP-A) was lowest in the group with ART/PGT-A/FET and the highest result was obtained in the group with ART/no PGT-A/FET. Statistically significant difference in the median PAPP-A levels was identified among the examined groups (p = .0186). When a subgroup analysis was performed, a statistically significant difference was observed in the median PAPP-A between ART/PGT-A/FET group versus ART/no PGT-A/FET group (p = .01) and NC versus ART/no PGT-A/FET (p = .01). A similar trend toward statistical significance was noted when comparing NC versus ART/no PGT-A/fresh ET (p = .06). Multivariate analysis elucidated that when age is present in the model, the effect of any method of conception or testing for aneuploidy disappears. The other factors (BMI, ethnicity, and parity) do not influence the levels of PAPP-A. The lowest median free human chorionic gonadotropin (ß-HCG) was recorded in the NC group and the highest result was identified in the group with IVF/PGT-A/FET. No statistically significant difference was observed in the median concentration levels of free ß-hCG among the compared groups (p = .5789) and when subgroup analysis was performed (p>.05). The normality of the distribution of variables was analyzed by the Kolmogorov-Smirnov test and the median PAPP-A and free ßhCG concentration difference by the Wilcoxon rank-sum test with nonparametric ANOVA. CONCLUSIONS: Testing for aneuploidy (PGT-A) and the decision to transfer either fresh or cryopreserved embryos (ET) appear not to affect the levels of first trimester biochemical markers. The findings of the present study should be a baseline for future studies and could be used to improve the antenatal screening counseling for women with ART pregnancies and PGT-A.

Isthmocele and ovarian stimulation for IVF: considerations for a reproductive medicine specialist.

STUDY QUESTION: What is the risk of developing intracavitary fluid (ICF) during ovarian stimulation in patients with an isthmocele after previous caesarean section (CS) delivery? SUMMARY ANSWER: In patients with an existing isthmocele, the risk of developing ICF during hormonal stimulation for IVF is almost 40%; therefore, special attention has to be paid to exclude fluid accumulation during stimulation and particularly at the time of transfer, in which case the reproductive outcomes of frozen embryo transfer (FET) cycles appear to be uncompromised. WHAT IS KNOWN ALREADY: Lately, there is an increasing focus on the long-term impact of CS delivery on the health and future fertility of the mother. Development of an isthmocele is one of the sequelae of a CS delivery. The presence of ICF in combination with an isthmocele has been described previously, and the adverse effect of endometrial fluid on implantation is well recognised by reproductive medicine specialists. Accumulation of ICF has been previously described in patients with hydrosalpinx, less commonly in patients with polycystic ovary syndrome undergoing ovarian stimulation for IVF/ICSI, and even in some patients without any identifiable reason. Assisted reproductive techniques (ARTs) are a means to overcome infertility. Reproductive medicine specialists commonly see patients with secondary infertility with a history of having had one or more previous CS and with ultrasound confirmation of an isthmocele. However, the available data pertaining to the prevalence of intracavitary fluid during ovarian stimulation in patients with ultrasound confirmation of an isthmocele is limited. Furthermore, data on the influence of ICF in a stimulated cycle on the ART outcome of a subsequent FET cycle is scarce and merits further studies. STUDY DESIGN, SIZE, DURATION: A prospective observational exploratory study was performed in IVI Middle East Fertility Clinic, Abu Dhabi, from June 2018 to March 2019, and retrospective analysis of the reproductive outcomes was performed until July 2019. PARTICIPANTS/MATERIALS, SETTING, METHODS: Patients with secondary infertility, defined as a minimum of 1 year of infertility after a previous successful pregnancy, undergoing ovarian stimulation for IVF/ICSI and having a history of one or more previous CS with ultrasonographic visible isthmocele, were included (n = 103). Patients were monitored as a clinical routine with vaginal ultrasound examinations during ovarian stimulation for IVF/ICSI treatment. All patients included in the study were asked to complete a questionnaire regarding their previous obstetric history. Development of ICF was recorded as well as changes in the measurements of the isthmocele during the course of ovarian stimulation. Reproductive outcomes of FET cycles of the patients with an isthmocele were retrospectively compared to those of patients with infertility and without isthmocele in our clinic during the same time period. MAIN RESULTS AND THE ROLE OF CHANCE: Patients with an existing isthmocele after previous CS have a risk of ~40% of developing ultrasonographic visible fluid in the endometrial cavity during the course of ovarian stimulation. Development of ICF was significantly correlated with the depth of the isthmocele on Day 2/3 (P = 0.038) and on the day of trigger (-1/-2 days) (P = 0.049), circumference of the isthmocele on the day of trigger (-1/-2 days) (P = 0.040), distance from the C-scar to the external os (P = 0.036), number of children delivered (P = 0.047) and number of previous CS (P = 0.035). There was a statistically significant increase in the parameters related to the size of the isthmocele during ovarian stimulation. No significant differences in the reproductive outcome (pregnancy rate and rates of biochemical and ectopic pregnancies, miscarriages and ongoing/delivered pregnancies) after FET were found between the patients with and without an isthmocele, when ICF was excluded prior to embryo transfer procedure. LARGE-SCALE DATA: NA. LIMITATIONS, REASONS FOR CAUTION: This study was not primarily designed to investigate the causes of ICF during ovarian stimulation or to evaluate the reproductive outcomes. Further, the small number of reported reproductive outcomes may be seen as a limitation. WIDER IMPLICATIONS OF THE FINDINGS: The data highlights the need for an increased awareness on the part of reproductive medicine specialists towards the potentially adverse impact of an isthmocele on ART treatment, as there is a potential to develop intracavitary fluid during ovarian stimulation for IVF. The increase in the circumference of the isthmocele may increase embryo transfer difficulty. STUDY FUNDING/COMPETING INTEREST(S): No funding of the study has to be reported. The authors have no competing interests. TRIAL REGISTRATION NUMBER: This prospective study was registered with clinicaltrials.gov. under the number NCT03518385.

Ethnical and sociocultural differences causing infertility are poorly understood-insights from the Arabian perspective.

Infertility is acknowledged worldwide as a major health concern. Although global levels of primary and secondary infertility have hardly changed between 1990 and 2010, significant regional differences have been reported. The prevalence of infertility in women has been estimated to be one in every seven couples in the western world and one in every four couples in developing countries. Male infertility may be under-reported in some regions due to an unwillingness of the male partner to undergo fertility investigations. Geographical, sociocultural/religious and ethnical dissimilarities contribute to these global variations in infertility prevalence. Infertility has a major impact on family stability in many cultures, especially in developing countries, where childlessness can impact sociocultural status. Moreover, it is important to realise that most fertility treatment protocols are based on studies performed in Caucasian population. The purpose of this opinion paper is to critically appraise the existing evidence regarding the association between infertility and relevant sociocultural factors in Middle East countries focusing on aspects such as parental consanguinity, obesity and vitamin D deficiency. There may be reason to believe that in addition to the current standard evaluation of infertile couples, region-specific counselling and treatment modalities are required.

Recurrent implantation failure: definition and management.

Recurrent implantation failure refers to failure to achieve a clinical pregnancy after transfer of at least four good-quality embryos in a minimum of three fresh or frozen cycles in a woman under the age of 40 years. The failure to implant may be a consequence of embryo or uterine factors. Thorough investigations should be carried out to ascertain whether there is any underlying cause of the condition. Ovarian function should be assessed by measurement of antral follicle count, FSH and anti-Mu¨llerian hormone. Increased sperm DNA fragmentation may be a contributory cause. Various uterine pathology including fibroids, endometrial polyps, congenital anomalies and intrauterine adhesions should be excluded by ultrasonography and hysteroscopy. Hydrosalpinges are a recognized cause of implantation failure and should be excluded by hysterosalpingogram; if necessary, laparoscopy should be performed to confirm or refute the diagnosis. Treatment offered should be evidence based, aimed at improving embryo quality or endometrial receptivity. Gamete donation or surrogacy may be necessary if there is no realistic chance of success with further IVF attempts.

The clinical characteristics of women with recurrent implantation failure.

Recurrent implantation failure (RIF) refers to failure to conceive after three or more in vitro fertilisation (IVF) or embryo transfer cycles. Implantation failure may be due to embryo or uterine factors. There are many controversies surrounding the investigation and management of this condition. The aim of our study was to describe the clinical characteristics and the outcome of investigations of a group of women with recurrent implantation failure. A total of 111 couples with RIF were managed in a dedicated clinic and investigated according to a clinic protocol. The frequency of abnormal investigations were as follows: high (≥ 10 IU/l) FSH, 14/107(13%); high free androgen index 6/78(8%); abnormal hysteroscopic findings 7/45(16%); hydrosalpinges 8/33(24%); persistently elevated ACA or tested positive for lupus anticoagulant 19/108 (18%); abnormal karyotype analysis 3/101(3%); hyperprolactinaemia 1/79(1%); abnormal thyroid function 4/100(4%) and tested positive for thyroid peroxidase antibody 10/104(10%). Specific treatments according to the results of investigation produced a live birth rate of 29%. It was concluded that the findings should help practitioners to construct suitable investigation protocols for the initial management of this condition.

Vitamin D receptor agonists inhibit pro-inflammatory cytokine production from the respiratory epithelium in cystic fibrosis.

BACKGROUND: 1,25-Dihydroxycholecalciferol (1,25(OH)(2)D(3)) has been shown to mitigate epithelial inflammatory responses after antigen exposure. Patients with cystic fibrosis (CF) are at particular risk for vitamin D deficiency. This may contribute to the exaggerated inflammatory response to pulmonary infection in CF. METHODS: CF respiratory epithelial cell lines were exposed to Pseudomonas aeruginosa lipopolysaccharide (LPS) and Pseudomonas conditioned medium (PCM) in the presence or absence of 1,25(OH)(2)D(3) or a range of vitamin D receptor (VDR) agonists. Levels of IL-6 and IL-8 were measured in cell supernatants, and cellular total and phosphorylated IκBα were determined. Levels of human cathelicidin antimicrobial peptide (hCAP18) mRNA and protein were measured in cells after treatment with 1,25(OH)(2)D(3). RESULTS: Pretreatment with 1,25(OH)(2)D(3) was associated with significant reductions in IL-6 and IL-8 protein secretion after antigen exposure, a finding reproduced with a range of low calcaemic VDR agonists. 1,25(OH)(2)D(3) treatment led to a decrease in IκBα phosphorylation and increased total cellular IκBα. Treatment with 1,25(OH)(2)D(3) was associated with an increase in hCAP18/LL-37 mRNA and protein levels. CONCLUSIONS: Both 1,25(OH)(2)D(3) and other VDR agonists significantly reduce the pro-inflammatory response to antigen challenge in CF airway epithelial cells. VDR agonists have significant therapeutic potential in CF.

Is it safe to prescribe clomiphene citrate without ultrasound monitoring facilities?

The majority of triplet and higher order multiple pregnancies now result from ovulation induction/superovulation rather than in vitro fertilisation. However, clomiphene citrate is still widely prescribed by gynaecologists and general practitioners who do not have access to ultrasound monitoring. The objective of our study was to determine the prevalence of multifollicular development with different doses of clomiphene citrate. A retrospective review of transvaginal ultrasound monitoring of 425 cycles in 182 women receiving clomiphene citrate from January 2002 to December 2003, was studied. Three or more follicles of >or= 14 mm were identified in 58 cycles (14%). Patients received 50 mg of clomiphene citrate in 52 of these 58 cycles and 25 mg in the remaining six. One patient was noted to have developed five follicles and 10 patients developed four follicles. One patient developed six follicles, despite receiving only 25 mg clomiphene citrate daily. It was concluded that a significant number of women (14%) developed three or more follicles, despite receiving low doses of clomiphene citrate.

Vaginal cytology following primary hysterectomy for cervical cancer: is it useful?

BACKGROUND: Vaginal intraepithelial neoplasia (VAIN) is usually detected in patients with synchronous or antecedent cervical or vulval intraepithelial or invasive cancer. VAIN has the potential to progress to malignancy. AIMS: To determine the incidence and severity and analyse the management of vaginal dysplasia in patients undergoing primary hysterectomy for cervical cancer. METHODS: A retrospective study (1984-1998) identified 210 primary invasive cervical cancers. One-hundred and twenty-three patients had a primary hysterectomy. RESULTS: In follow-up six patients were found to have dyskaryosis in a second vaginal smear. Biopsies in the six patients with colposcopic lesions showed VAIN II (n=2), VAIN III (n=1),VAIN III / possible early invasion (n = 1) and invasive carcinoma (n=2). One patient with recurrent squamous cancer received salvage radiotherapy and one with recurrent adenocarcinoma received high dose progestogens and topical 5-fluorouracil. CONCLUSION: All patients are disease-free at follow-up.

Expression and coreceptor function of APJ for primate immunodeficiency viruses.

APJ is a seven transmembrane domain G-protein-coupled receptor that functions as a coreceptor for some primate immunodeficiency virus strains. The in vivo significance of APJ coreceptor function remains to be elucidated, however, due to the lack of an antibody that can be used to assess APJ expression, and because of the absence of an antibody or ligand that can block APJ coreceptor activity. Therefore, we produced a specific monoclonal antibody (MAb 856) to APJ and found that it detected this receptor in FACS, immunofluorescence, and immunohistochemistry studies. MAb 856 also recognized APJ by Western blot, enabling us to determine that APJ is N-glycosylated. Using this antibody, we correlated APJ expression with coreceptor activity and found that APJ had coreceptor function even at low levels of expression. However, we found that APJ could not be detected by FACS analysis on cell lines commonly used to propagate primate lentiviruses, nor was it expressed on human PBMC cultured under a variety of conditions. We also found that some viral envelope proteins could mediate fusion with APJ-positive, CD4-negative cells, provided that CD4 was added in trans. These findings indicate that in some situations APJ use could render primary cell types susceptible to virus infection, although we have not found any evidence that this occurs. Finally, the peptide ligand for APJ, apelin-13, efficiently blocked APJ coreceptor activity.

Expression of multiple functional chemokine receptors and monocyte chemoattractant protein-1 in human neurons.

Functional chemokine receptors and chemokines are expressed by glial cells within the CNS, though relatively little is known about the patterns of neuronal chemokine receptor expression and function. We developed monoclonal antibodies to the CCR1, CCR2, CCR3, CCR6, CXCR2, CXCR3 and CXCR4 chemokine receptors to study their expression in human fetal neurons cultured from brain tissue as well as the clonally derived NT2.N human neuronal cell line (NTera 2/cl.D1). Specific monoclonal antibody labeling demonstrated expression of CCR2, CXCR2, CXCR3 and CXCR4 on neurons from both sources. Co-labeling studies revealed strong expression of CXCR3 and CXCR4 on both dendritic and axonal processes, with a weaker expression of CXCR2 and CCR2. Reverse transcriptase-polymerase chain reaction analysis of pure NT2.N neurons confirmed RNA expression for CCR2, CXCR2, CXCR3 and CXCR4. No changes in the neuronal labeling pattern of chemokine receptor expression were noted when NT2.N neurons were grown on a supporting layer of astrocytes, again consistent with similar patterns seen in primary human fetal brain cultures. Analysis of single-cell calcium transients revealed a robust response to stromal derived factor-1alpha (CXCR4) and melanocyte growth-stimulating activity (CXCR2), and variable response to monocyte chemoattractant protein-1 (CCR2) or interferon-gamma inducible protein-10 (CXCR3). Finally, we detected the release of monocyte chemoattractant protein-1 from pure cultures of NT2.N neurons, but not undifferentiated NT2 cells. These data indicate that individual neurons may not only co-express multiple functional chemokine receptors, but also that neurons themselves produce chemokines which may influence cellular function within the central nervous system.

Factors influencing the processing and function of the amyloid beta precursor protein--a potential therapeutic target in Alzheimer's disease?

The amyloid beta precursor protein (AbetaPP), which plays a pivotal role in Alzheimer's disease (AD), can exist as either a membrane-bound or soluble protein. The former is cleaved at the level of the plasma membrane to generate the soluble form of the protein (AbetaPP(s)). An alternative pathway exists, however, for the cleavage of AbetaPP to generate a 40-42 amino acid peptide termed amyloid beta (Abeta), either within the lysosomal or the endoplasmic reticulum/Golgi compartments of the cell. In AD, there is an increase in the ratio of the 42 amino acid form of the Abeta peptide (Abeta(42)) to Abeta(40). The Abeta(42) form is the more amyloidogenic form and has an increased potential to form the insoluble amyloid deposits characteristic of AD pathology. Studies on the familial form of the disease, with mutations in AbetaPP or in the presenilin proteins, have confirmed an increase in Abeta(42) generation associated with the early stages of the disease. This review will examine the factors that influence AbetaPP processing, how they may act to modulate the biological effects of AbetaPP(s) and Abeta, and if they provide a viable target for therapeutic intervention to modify the rate of progression of the disease.

The effect of corticosteroids on amyloid beta precursor protein/amyloid precursor-like protein expression and processing in vivo.

In this study, we have investigated the effect of altered corticosteroid levels on the expression and processing of the amyloid beta precursor protein (A betaPP) and its amyloid precursor-like protein (APLP) homologue in rat brain. Four groups of animals were used in the study: sham operated, adrenalectomised, and adrenalectomised treated with either dexamethasone or aldosterone, with the A betaPP/APLP expression being determined by western blot analysis. While there were no changes in the levels of A betaPP/APLP following adrenalectomy, treatment with dexamethasone, but not aldosterone, resulted in a marked increase in protein expression levels with the level of increase varying between the brain regions examined. Corticosteroids had a more marked effect on the particulate rather than the soluble form of the protein, thus suggesting that elevated glucocorticoids may also be adversely influencing A betaPP/APLP processing.

Relationship among mental stress-induced ischemia and ischemia during daily life and during exercise: the Psychophysiologic Investigations of Myocardial Ischemia (PIMI) study.

OBJECTIVES: The purposes of this database study were to determine: 1) the relationship between mental stress-induced ischemia and ischemia during daily life and during exercise; 2) whether patients who exhibited daily life ischemia experienced greater hemodynamic and catecholamine responses to mental or physical stress than patients who did not exhibit daily life ischemia, and 3) whether patients who experienced daily life ischemia could be identified on the basis of laboratory-induced ischemia using mental or exercise stress testing. BACKGROUND: The relationships between mental stress-induced ischemia in the laboratory and ischemia during daily life and during exercise are unclear. METHODS: One hundred ninety-six stable patients with documented coronary disease and a positive exercise test underwent mental stress testing and bicycle exercise testing. Radionuclide ventriculography and electrocardiographic (ECG) monitoring were performed during the mental stress and bicycle tests. Patients underwent 48 h of ambulatory ECG monitoring. Hemodynamic and catecholamine responses were obtained during mental stress and bicycle tests. RESULTS: Ischemia (reversible left ventricular dysfunction or ST segment depression > or = 1 mm) developed in 106 of 183 patients (58%) during the mental stress test. There were no significant differences in clinical characteristics of patients with, compared with those without, mental stress-induced ischemia. Patients with mental stress ischemia more often had daily life ischemia than patients without mental stress ischemia, but their exercise tests were similar. Patients with daily life ischemia had higher ejection fraction and cardiac output, and lower systemic vascular resistance during mental stress than patients without daily life ischemia. Blood pressure and catecholamine levels at rest and during the mental stress tests were not different in patients with, compared with those without, daily life ischemia. Patients with daily life ischemia had a higher ejection fraction at rest and at peak bicycle exercise compared with patients without daily life ischemia, but there were no other differences in peak hemodynamic or catecholamine responses to exercise. The presence of ST segment depression during routine daily activities was best predicted by ST segment depression during mental or bicycle exercise stress, although ST segment depression was rare during mental stress. CONCLUSIONS: Patients with daily life ischemia exhibit a heightened generalized response to mental stress. ST segment depression in response to mental or exercise stress is more predictive of ST segment depression during routine daily activities than other laboratory-based ischemic markers. Therapeutic management strategies might therefore focus on patients with these physiologic responses to stress and on whether lessening such responses reduces ischemia.

The role of the protein glycosylation state in the control of cellular transport of the amyloid beta precursor protein.

The amyloid beta precursor protein can exist as both a membrane-bound and a secreted protein, with the former having the potential to generate the amyloid beta peptide present in the neuritic plaques which are characteristic of Alzheimer's disease. In this study, we have used a clone of the AtT20 mouse pituitary cell line which expresses high levels of the amyloid beta precursor protein to characterize the glycosylation state of the secreted and membrane-bound forms of the protein and to examine the role of post-translational modifications in protein processing. Lectin blot analysis of immunoprecipitated amyloid beta precursor protein demonstrated that the soluble form of the protein contains significant amounts of sialic acid, with the lectin staining being reduced in the particulate cellular fractions. Treatment of the cells with mannosidase inhibitors to interfere with the formation of complex-type N-linked glycans resulted in a decrease in secreted amyloid beta precursor protein and an increase in the level of the cellular form of the protein. The increase in amyloid beta precursor protein levels in the cellular fraction was accompanied by an increase in perinuclear staining. Furthermore, cells overexpressing the alpha2,6(N)-sialyltransferase enzyme also demonstrated an increase in amyloid beta precursor protein secretion. These results suggest that the presence of terminal sialic acid residues on complex-type N-glycans may be required for the optimal transport of the amyloid beta precursor protein from the Golgi to the cell membrane with the subsequent cleavage to generate the secreted form of the protein.

The role of glycoproteins in neural development function, and disease.

Glycoproteins play key roles in the development, structuring, and subsequent functioning of the nervous system. However, the complex glycosylation process is a critical component in the biosynthesis of CNS glycoproteins that may be susceptible to the actions of toxicological agents or may be altered by genetic defects. This review will provide an outline of the complexity of this glycosylation process and of some of the key neural glycoproteins that play particular roles in neural development and in synaptic plasticity in the mature CNS. Finally, the potential of glycoproteins as targets for CNS disorders will be discussed.

Glucocorticoid induction of the alpha2,6 sialyltransferase enzyme in a mouse neural cell line.

Combined sialyltransferase (ST) activities were induced in the HN9 hippocampal cell line following treatment with the synthetic glucocorticoid dexamethasone (dex) for 24 hr. Induction occurred in a dose-dependent manner, with the maximum induction of a 2-fold increase over control enzyme levels occurring at a concentration of 10(-8) M dex. A minimum of 6 hr pretreatment with drug was required before significant induction could be detected and elevated enzyme levels persisted for up to 48 hr post-treatment. The induced form of the enzyme showed an increase in reaction maximum velocity (Vmax) while showing no change in affinity (Km) for the acceptor substrate asialofetuin. The alpha2,6 ST enzyme was demonstrated to be the primary enzyme induced and there was no change in expression of the alpha2,3 ST enzyme. Lectin blot analysis demonstrated an increase in the levels of the alpha2,6-linked cellular sialoglycoproteins and a parallel decrease in the alpha2,3 sialoglycoprotein levels.

The effect of corticosteroids on serum sialyltransferase enzyme activities in the rat.

Previous studies have demonstrated corticosteroid regulation of sialyltransferase (sialyl-T) enzyme activities in a number of different tissues throughout the body. In this study we examined the regulatory effect of corticosteroids on serum enzyme activity in the rat. The total serum sialyl-T activity was not affected by a decrease in corticosteroid levels following adrenalectomy. However, while there was a significant increase in enzyme activity following dexamethasone treatment, aldosterone had no effect on this parameter. Subsequent examination of individual sialyl-T enzymes demonstrated a slight decrease in alpha2,6 sialyl-T activity following adrenalectomy which was restored to basal levels following dexamethasone treatment. The activity of the alpha2,3 sialyl-T enzyme was not affected by adrenalectomy or dexamethasone treatment, but was stimulated significantly by aldosterone. In general, the levels of serum sialoglycoproteins mirrored well the activities of the appropriate sialyl-T enzymes. These results demonstrate that serum sialyltransferase activity in the rat is under the influence of circulating corticosteroids.

The biochemical consequences of alpha2,6(N) sialyltransferase induction by dexamethasone on sialoglycoprotein expression in the rat H411e hepatoma cell line.

Previous studies have demonstrated sialyltransferase (ST) enzyme activity to be induced in hepatic cells by corticosteroids. In this study, we used the H411e rat hepatoma cell line to further characterise this induction with particular reference to the subsequent changes in the pattern of sialoglycoprotein (SGP) expression. The induction of total ST activity by dexamethasone was concentration dependent with maximum induction occurring 12 h subsequent to drug addition. Western blot analysis demonstrated that the induction was associated with an increase in the expression of the alpha2,6(N) ST enzyme with no change in the expression levels of the alpha2,3(N) enzyme. While the induction resulted in an increase in the reaction velocity (Vmax) of the enzyme for both the sugar donor (CMP-Neu5Ac) and the asialofetuin acceptor protein, there was no significant change in the enzyme affinity (Km) for the substrates, suggestive of either an increase in the expression or efficiency of the existing enzyme(s) rather than an induction of novel ST enzymes. Lectin blot analysis of cellular glycoprotein expression demonstrated no change in the expression patterns of either alpha2,3 or alpha2,6-linked SGP following enzyme induction. These results suggest that the available acceptor sites for the terminal sialic acid group(s) may be fully occupied in the control cells and therefore there are no further sites onto which the sialic acid can be transferred following induction of ST enzyme activity. This may be due to the high basal enzyme levels in the control cells already exhausting endogenous acceptor sites.