The Mediating Role of Emotion Dysregulation in the Association Between Perfectionism and Eating Psychopathology Symptoms.

INTRODUCTION: This study explored the possible mediating role of emotion dysregulation in the association between perfectionism and eating psychopathology symptoms. METHOD: One hundred forty-two outpatients with eating disorders (EDs) were enrolled. Perfectionism, emotion dysregulation, ED psychopathology, anxious and depressive symptoms were assessed. Correlation, mediation and 95% bias corrected and accelerated (BCa CI) bootstrapped analyses were run. RESULTS: Emotion dysregulation was found to mediate the association between concern over mistakes perfectionism and restraint (indirect effect: 0.093, BCa CI: 0.001-0.02, adjusted R2 = 0.3324, p < 0.001), shape concern (indirect effect: 0.0130, BCa CI: 0.004-0.03, adjusted R2 = p < 0.001) and weight concern (indirect effect: 0.0142, BCa CI: 0.004-0.03, adjusted R2 = 0.2986, p < 0.001). CONCLUSION: Among ED outpatients, emotion dysregulation may be involved in the association between concern over mistakes perfectionism and persistence of eating psychopathology symptoms. Emotion dysregulation could be considered as possible therapeutic target to reduce the persistence, and severity, of eating psychopathology symptoms among ED patients with concern over mistakes perfectionism.

The Metacognitions about Binge Eating Questionnaire: Investigation of the association between specific metacognitions and Binge Eating Disorder.

Literature suggested that metacognitions are involved in eating problems and may be relevant to the understanding of Binge Eating Disorder (BED). The goal of the current studies was to develop the first self-report instrument on metacognitions about binge eating. In Study 1, a community sample completed the Metacognitions about Binge Eating Questionnaire (MBEQ); an Exploratory Factor Analysis (EFA) was performed. In study 2, a community sample completed the MBEQ and measures assessing severity of binge eating, irrational food beliefs, anxiety, depression, impulsiveness. A Confirmatory Factor Analysis (CFA) was performed. Concurrent and incremental validity were assessed. In study 3, a clinical sample of participants with a diagnosis of BED completed the MBEQ and other measures. Bivariate correlational analysis and hierarchical linear regression were performed. Participants from the general population and participants with a diagnosis of BED were compared. EFA and CFA supported a two-factor solution consisting of positive and negative metacognitions about binge eating. Concurrent and incremental validity were acceptable. The metacognitions factors correlated positively with anxiety, depression, irrational food beliefs, impulsiveness in the community sample, and anxiety, irrational food beliefs, impulsiveness in clinical sample. The metacognitions factors contributed to the prediction of BEDs symptoms, in community and clinical samples, over and above age, gender, impulsiveness, anxiety, depression, irrational food beliefs. The MBEQ possesses good psychometric properties and appears a reliable and valid measure of positive and negative metacognitions about binge eating. Metacognitions about binge eating could be a therapeutic target to reduce the severity of binge eating episodes.

Circulating IL-17A Levels in Postmenopausal Women with Primary Hyperparathyroidism.

BACKGROUND: Primary hyperparathyroidism (PHPT) is a common cause of secondary osteoporosis in postmenopausal women. Th17 lymphocytes and the released cytokine IL-17A play an important role in bone metabolism. Th17 cells have been shown to be activated by PTH, and peripheral blood T cells from patients affected with PHPT express higher levels of IL-17A mRNA than controls. AIM: To investigate circulating levels of IL-17A and the ratio RANKL/OPG, as markers of osteoclastogenesis, in 50 postmenopausal PHPT women compared with postmenopausal osteoporotic non-PHPT women (n = 20). RESULTS: Circulating levels of IL-17A were similarly detectable in most PHPT and non-PHPT osteoporotic women (12.9 (8.4-23.1) vs. 11.3 (8.3-14.3) pg/ml, median (range interquartile), P = 0.759), at variance with premenopausal women where IL-17A was undetectable. In PHPT women, any significant correlations could be detected between circulating IL-17A levels and PTH levels. Nonetheless, significant negative correlations between circulating IL-17A and ionized calcium levels (r = -0.294, P = 0.047) and urine calcium excretions (r = -0.300, P = 0.045) were found. Moreover, PHPT women were characterized by positive correlations between IL-17A levels and femur neck (r = 0.364, P = 0.021) and total hip (r = 0.353, P = 0.015) T-scores. Circulating IL-17A levels did not show any significant correlation with sRANKL, OPG, and sRANKL/OPG ratio in PHPT women. CONCLUSIONS: In postmenopausal PHPT women, circulating IL-17A levels were similar to those detected in postmenopausal non-PHPT women, showing a disruption of the relationship observed in postmenopausal osteoporosis among circulating PTH, sRANKL, OPG, IL-17A, and bone demineralization in postmenopausal PHPT women. The data support an osteogenic effect of IL-17A in postmenopausal PHPT women.

Bone involvement and mineral metabolism in Williams' syndrome.

CONTEXT: The previous studies suggested a possible increased risk of hypercalcaemia and reduced bone mineral density (BMD) in Williams' syndrome (WS). However, an extensive study regarding bone metabolism has never been performed. OBJECTIVE: To investigate bone health in young adults with WS. DESIGN: Cross-sectional study. SETTINGS: Endocrinology and Metabolic Diseases and Medical Genetic Units. PATIENTS: 29 WS young adults and 29 age- and sex-matched controls. MAIN OUTCOME MEASURES: In all subjects, calcium, phosphorus, bone alkaline phosphatase (bALP), parathyroid hormone (PTH), 25-hydroxyvitamin D (25OHVitD), osteocalcin (OC), carboxyterminal cross-linking telopeptide of type I collagen (CTX), 24-h urinary calcium and phosphorus, femoral-neck (FN) and lumbar-spine (LS) BMD and vertebral fractures (VFx) were assessed. In 19 patients, serum fibroblast growth factor-23 (FGF23) levels were measured. RESULTS: WS patients showed lower phosphorus (3.1 ± 0.7 vs 3.8 ± 0.5 mg/dL, p = 0.0001) and TmP/GFR (0.81 ± 0.32 vs 1.06 ± 0.25 mmol/L, p = 0.001), and an increased prevalence (p = 0.005) of hypophosphoremia (34.5 vs 3.4%) and reduced TmP/GFR (37.9 vs 3.4%). Moreover, bALP (26.3 ± 8.5 vs 35.0 ± 8.0 U/L), PTH (24.5 ± 12.6 vs 33.7 ± 10.8 pg/mL), OC (19.4 ± 5.3 vs 24.5 ± 8.7 ng/mL), and FN-BMD (- 0.51 ± 0.32 vs 0.36 ± 0.32) were significantly lower (p < 0.05), while CTX significantly higher (401.2 ± 169.3 vs 322.3 ± 122.4 pg/mL, p < 0.05). Serum and urinary calcium and 25OHVitD levels, LS-BMD and VFx prevalence were comparable. No cases of hypercalcemia and suppressed FGF23 were documented. Patients with low vs normal phosphorus and low vs normal TmP/GFR showed comparable FGF23 levels. FGF23 did not correlate with phosphorus and TmP/GFR values. CONCLUSIONS: Adult WS patients have reduced TmP/GFR, inappropriately normal FGF23 levels and an uncoupled bone turnover with low femoral BMD.

Denosumab or oral bisphosphonates in primary osteoporosis: a "real-life" study.

PURPOSE: To compare the response to denosumab (DMAb) therapy with that of oral bisphosphonate (BISPH) treatment in postmenopausal women with primary osteoporosis (PO). METHODS: In this retrospective study, we compared data of 75 PO female patients treated for 24 months with DMab (DMAb Group, age 72.6 ± 8.9 years) with those of 75 PO patients treated with oral bisphosphonates (BISPH Group), matched for age, body mass index, femoral bone mineral density (BMD), prevalent fragility fractures and familiar history of hip fracture. In all subjects at baseline and after 24 months we assessed the calcium-phosphorous metabolism parameters, BMD at lumbar spine (LS-BMD) and femoral neck (FN-BMD) by dual X-ray absorptiometry and the morphometric vertebral fractures by radiograph. The patients were considered inadequate responders in the presence of ≥ 2 incident fragility fractures and/or a decrease in BMD greater than the least significant change (LS 2.8%, FN 5.9%). RESULTS: After 24 months, the DMab Group showed a greater ALP decrease (- 22.8 ± 18.2%), a higher LS-BMD and FN-BMD increase (6.6 ± 6.9 and 4.4 ± 8.2%, respectively) and a lower number of patients with an incident fracture (8%) and with an inadequate response (6.7%) than BISPH Group (- 14.9 ± 15.3, 2.5 ± 4.3, 1.9 ± 4.5, 21.3 and 22.7%, respectively, p < 0.05 for all comparisons). The inadequate response was 4.5-fold more likely in BISPH Group than in DMab one (p = 0.027), regardless of possible confounders. CONCLUSIONS: In postmenopausal PO females, denosumab was more effective than oral bisphosphonates in increasing BMD and reducing bone turnover and the number of inadequate responder patients.

Predictability of hypoadrenalism occurrence and duration after adrenalectomy for ACTH-independent hypercortisolism.

OBJECTIVE: To evaluate if the parameters of hypothalamic-pituitary-adrenal (HPA) axis activity could predict the occurrence and duration of post-surgical hypocortisolism (PSH) in patients with Cushing's syndrome (CS) and with adrenal incidentaloma (AI). METHODS: We studied 80 patients (54 females, age 53.3 ± 11 years), who underwent adrenalectomy for CS (17 patients) or for AI (53 patients). Before surgery, we measured adrenocorticotroph hormone (ACTH), urinary free cortisol (UFC) and serum cortisol after 1 mg dexamethasone suppression test (1 mg-DST) levels. After surgery, all patients were given a steroid replacement therapy, and PSH was searched after 2 months by a low-dose (1 µg, iv) corticotropin stimulation test, that was repeated every 6 months in PSH patients for at least 4 years. RESULTS: The PSH occurred in 82.4 and 46% of CS and AI patients, respectively. In the whole sample and in AI patients separately considered, the PSH was independently predicted by the preoperative cortisol levels after 1 mg-DST, however, with a low (< 70%) accuracy. In AI patients the PSH occurrence was not ruled out even by the cortisol levels after 1 mg-DST lower than 1.8 µg/dL (50 nmol/L). In the 50% of CS patients and in 31% of AI patients the PSH lasted more than 18 months and in 35.7% of CS patients it persisted for more than 36 months. In AI patients, the PSH duration was not predictable by any parameter. However, a PSH duration of at least 12 months was significantly predicted before adrenalectomy (sensitivity 91.7%, specificity 41.2%, positive predictive value 52.4%, negative predictive value 87.5%, p = 0.05) by the presence of at least 2 out of low ACTH levels, increased UFC levels and cortisol levels after 1 mg-DST ≥ 3.0 µg/dL (83 nmol/L). CONCLUSION: The PSH occurrence and its duration are hardly predictable before surgery. All patients undergoing unilateral adrenalectomy should receive a steroid substitutive therapy.

Clinical presentation and management of patients with primary hyperparathyroidism in Italy.

PURPOSE: Evaluation of the phenotype of primary hyperparathyroidism (PHPT), adherence to International Guidelines for parathyroidectomy (PTx), and rate of surgical cure. METHOD: From January 2014-January 2016, we performed a prospective, multicenter study in patients with newly diagnosed PHPT. Biochemical and instrumental data were collected at baseline and during 1-year follow-up. RESULTS: Over the first year we enrolled 604 patients (age 61 ± 14 years), mostly women (83%), referred for further evaluation and treatment advice. Five hundred sixty-six patients had sporadic PHPT (93.7%, age 63 ± 13  years), the remaining 38 (6.3%, age 41 ± 17  years) had familial PHPT. The majority of patients (59%) were asymptomatic. Surgery was advised in 281 (46.5%). Follow-up data were available in 345 patients. Eighty-seven of 158 (55.1%) symptomatic patients underwent PTx. Sixty-five (53.7%) of 121 asymptomatic patients with at least one criterion for surgery underwent PTx and 56 (46.3%) were followed without surgery. Negative parathyroid imaging studies predicted a conservative approach [symptomatic PHPT: OR 18.0 (95% CI 4.2-81.0) P < 0.001; asymptomatic PHPT: OR 10.8, (95% CI 3.1-37.15) P < 0.001). PTx was also performed in 16 of 66 (25.7%) asymptomatic patients without surgical criteria. Young age, serum calcium concentration, 24 h urinary calcium, positive parathyroid imaging (either ultrasound or MIBI scan positive in 75% vs. 16.7%, P = 0.001) were predictors of parathyroid surgery. Almost all (94%) of patients were cured by PTx. CONCLUSIONS: Italian endocrinologists do not follow guidelines for the management of PHPT. Negative parathyroid imaging studies are strong predictors of a non-surgical approach. PTx is successful in almost all patients.

The utility of lumbar spine trabecular bone score and femoral neck bone mineral density for identifying asymptomatic vertebral fractures in well-compensated type 2 diabetic patients.

UNLABELLED: The objective of the study was to evaluate the usefulness of trabecular bone score (TBS) and bone mineral density (BMD) for identifying vertebral fractures (VFx) in well-compensated type 2 diabetic (T2D) patients. TBS and femoral neck BMD below certain cutoffs may be useful for identifying VFx in well-compensated T2D patients. INTRODUCTION: In T2D, the prevalence of VFx is increased, especially in poorly compensated and complicated diabetic patients. The possibility of predicting the fracture risk in T2D patients by measuring BMD and TBS, an indirect parameter of bone quality, is under debate. Therefore, the objective was to evaluate the usefulness of TBS and BMD for identifying VFx in well-compensated T2D patients. METHODS: Ninety-nine T2D postmenopausal women in good metabolic control (glycosylated haemoglobin 6.8 ± 0.7 %) and 107 control subjects without T2D were evaluated. In all subjects, we evaluated the following: the BMD at the lumbar spine (LS) and the femoral neck (FN); the TBS by dual X-ray absorptiometry; and VFx by radiography. In T2D subjects, the presence of diabetic retinopathy, neuropathy, and nephropathy was evaluated. RESULTS: T2D subjects had increased VFx prevalence (34.3 %) as compared to controls (18.7 %) (p = 0.01). T2D subjects presented higher BMD (LS -0.8 ± 1.44, FN -1.06 ± 1.08), as compared to controls (LS -1.39 ± 1.28, p = 0.002; FN -1.45 ± 0.91, p = 0.006, respectively). TBS was not different between diabetics and controls. In fractured T2D patients, LS-BMD, FN-BMD, and TBS were reduced (-1.2 ± 1.44; -1.44 ± 1.04; 1.072 ± 0.15) and the prevalence of retinopathy (15.4 %) was increased than in nonfractured T2D subjects (-0.59 ± 1.4, p = 0.035; -0.87 ± 1.05, p = 0.005; 1.159 ± 0.15, p = 0.006; 1.8 %, p = 0.04, respectively). The combination of TBS ≤1.130 and FN-BMD less than -1.0 had the best diagnostic accuracy for detecting T2D fractured patients (SP 73.8 %, SN 63.6 %, NPV 78.9 %, PPV 56.8 %). CONCLUSIONS: TBS and FN-BMD below certain cutoffs may be useful for identifying VFx in well-compensated T2D patients.

Lipid abnormalities in patients with adrenal incidentalomas: role of subclinical hypercortisolism and impaired glucose metabolism.

BACKGROUND: Subclinical hypercortisolism (SH) has been associated with metabolic complications such as type 2 diabetes mellitus, obesity and dyslipidemia. Scarce data are available regarding the lipid pattern abnormalities in SH, in relation to insulin resistance and impaired glucose metabolism (IGM). We aimed to evaluate the possible influence of SH on lipid pattern in relation to the presence/absence of impaired glucose metabolism. METHODS: In 338 patients with adrenal incidentaloma, the presence of SH, hypertension, dyslipidemia and IGM was evaluated. According to the presence of SH and IGM the patients were divided into 4 groups (IGM+SH+, IGM+SH-, IGM-SH+, IGM-SH-). We recruited 98 subjects without IGM (IGM-) and 100 with IGM (IGM+) as control groups. RESULTS: The prevalence of dyslipidemia was comparable among Group IGM+SH+, Group IGM+SH- and IGM+ controls (57.9, 58.4, 56%, P = NS). No difference in dyslipidemia prevalence among IGM- patients and IGM- controls was observed. The IGM+SH+ patients had a higher prevalence of dyslipidemia (57.9%) than IGM-SH+ ones (29.1%, P < 0.01). The IGM+SH- patients showed an increased prevalence of hypertension (76.6 vs 54.8%, P < 0.01) and dyslipidemia (58.4 vs 23.8%, P < 0.0001) as compared with IGM-SH- patients. Logistic regression analysis showed that only IGM was associated to dyslipidemia (OR 4.31, 95% CI 2.61-7.12, P = 0.0001) regardless of age, SH and gender. CONCLUSIONS: In the absence of alterations of glucose metabolism the presence of a subtle cortisol excess has no effect on lipid pattern. IGM seems to influence the lipid metabolism regardless of the presence of SH.

Factors associated with bisphosphonate treatment failure in postmenopausal women with primary osteoporosis.

UNLABELLED: Among 97 postmenopausal women with primary osteoporosis, adequate calcium and vitamin D supplementation, and good compliance to a 36-month bisphosphonate treatment, the 25.8% of patients are inadequate responders. Current smoking and a bone turnover in the upper part of the normal range increase the risk of treatment failure. INTRODUCTION: To evaluate the prevalence of the bisphosphonate treatment failure and its possible associated factors in women with primary osteoporosis (PO). METHODS: We studied 97 previously untreated postmenopausal women with PO and fragility fractures and/or a FRAX® 10-year probability of a major osteoporotic fracture ≥ 7.5%, before and after a 36-month treatment with alendronate or risedronate and adequate vitamin D supplementation with good compliance. At baseline and after 36 months, lumbar spine (LS) and femoral bone mineral density (BMD) were assessed by Dual X-ray absorptiometry and vertebral fractures by spinal radiographs. Spinal deformity index (SDI) was calculated. Treatment failure was defined by the presence of ≥ 2 incident fragility fractures and/or a BMD decrease greater than the least significant change. RESULTS: Bisphosphonate treatment failure was observed in 25.8% of patients. Age, body mass index, years since menopause, familiar history of hip fracture, number of falls, type of bisphosphonate used, 25-hydroxyvitamin D levels (25OHVitD), BMD, SDI, and FRAX® score at baseline were not different between responders and inadequate responders. Treatment failure was associated with current smoking (OR 3.22, 95% CI 1.10-9.50, P = 0.034) and baseline alkaline phosphatase total activity levels ≥ 66.5 U/L (OR 4.22, 95% CI 1.48-12.01, P = 0.007), regardless of age, number of falls, LS BMD, and baseline SDI. CONCLUSIONS: The 25.8 % of PO postmenopausal women inadequately responds to bisphosphonates, despite a good compliance to therapy and normal 25OHVitD levels. The current smoking and bone turnover in the upper part of the normal range are associated with the inadequate response to bisphosphonates.

Effects of different pre-treatments on the properties of polyhydroxyalkanoates extracted from sidestreams of a municipal wastewater treatment plant.

The paper deals with effects of two different widespread extraction methods (conventional extraction and Soxhlet extraction) and four different pre-treatments (homogenization with pressure and with blades, sonication, and impact with glass spheres) on the extraction yields and properties of polyhydroxyalkanoate (PHA) extracted from biomass coming from an innovative process (short-cut enhanced phosphorus and PHA recovery) applied in a real wastewater treatment plant. The results show that the two different extraction processes affected the crystallization degree and the chemical composition of the polymer. On the other hand, the extractive yield was highly influenced by pre-treatments: homogenization provided a 15% more extractive yield than the others. Homogenization, especially at high pressure, proved to be the best pre-treatment also in terms of the purity, visual appearance (transparency and clearness), thermal stability, and mechanical performances of the obtained PHA films. All the PHA films begin to melt long before their degradation temperature (Td > 200 °C): this allows their use in the fields of extrusion or compression moulding. SYNOPSIS: Optimizing the extraction of PHAs from municipal wastewater gives a double beneficial environmental impact: wastewater treatment and circular bio-based carbon upgrade to biopolymers for the production of bioplastics and other intersectoral applications.

Non classical complications of primary hyperparathyroidism.

Several studies suggested that the condition of primary hyperparathyroidism (PHPT) may be associated not only with the classical bone, kidney and gastrointestinal consequences, but also with cardiovascular, neuromuscular and articular complications, impaired quality of life and increased cancer risk. However, the only cardiovascular complications associated with PHPT, which seems to improve after parathyroidectomy, is left ventricular hypertrophy, while, data regarding the reversibility of hypertension, valve calcifications and increased vascular stiffness are inconsistent. Parathyroidectomy seems to ameliorate neuropsychological, cognitive disturbances and quality of life in moderate-severe PHPT, while data in mild PHPT are less clear. At variance, the effect of parathyroidectomy on neuromuscular and articular complications is still unknown, and no studies demonstrated a reduction of cancer risk after recovery from PHPT. Overall, to date, cardiovascular and neuropsychological evaluation are not recommended solely because of PHPT, nor cardiovascular disease, muscle weakness, and neuropsychological complications are indication for parathyroidectomy.

Nerve growth factor regulates gene expression by several distinct mechanisms.

To help elucidate the mechanisms by which nerve growth factor (NGF) regulates gene expression, we have identified and studied four genes (a-2, d-2, d-4, and d-5) that are positively regulated by NGF in PC12 cells, including one (d-2) which has previously been identified as a putative transcription factor (NGF I-A). Three of these genes, including d-2, were induced very rapidly at the transcriptional level, but the relative time courses of transcription and mRNA accumulation of each of these three genes were distinct. The fourth gene (d-4) displayed no apparent increase in transcription that corresponded to the increase in its mRNA, suggesting that NGF may regulate its expression at a posttranscriptional level. Thus, NGF positively regulates gene expression by more than one mechanism. These genes could also be distinguished on the basis of their response to cyclic AMP. The expression of d-2 and a-2 was increased by cholera toxin and further augmented by NGF; however, cholera toxin not only failed to increase the levels of d-5 and d-4 mRNA but also actually inhibited the NGF-dependent increase. The expression of each of these genes, including d-2 (NGF I-A), was also increased by fibroblast growth factor, epidermal growth factor (EGF), phorbol myristate acetate, and in some cases insulin, showing that the regulation of these genes is not unique to NGF. Because each of these genes was expressed in response to phorbol myristate acetate and EGF, their expression may be necessary but is certainly not sufficient for neurite formation. The protein kinase inhibitor K-252a prevented the NGF-associated, but not the acidic FGF-associated, induction of d-2 and d-5 gene expression, suggesting that these two growth factors may regulate gene expression via different cellular pathways. The study of the regulation of the expression of these and other NGF-inducible genes should valuable new information concerning how NGF and other growth factors cause neural differentiation.

Polarity and division site specification in yeast.

A significant component of polarization in budding yeast involves the regulated restructuring of the actin cytoskeleton in response to defined cellular signals. Recent evidence suggests that such cytoskeletal organization arises through the action of large protein complexes that form in response to signals from small GTP-binding proteins, such as Cdc42, Rho, and Ras. These actin-organizing complexes may be fairly diverse, but generally consist of one or more central scaffold proteins, such as those of the formin class, that bind to signaling molecules and recruit actin-binding proteins to bring about desired polarizing events.

A canopy layer model and its application to Rome.

An urban canopy layer model based on four energy balance equations at ground level and at building level was developed to simulate and describe the urban climate and the heat storage in an urban setting. Thermal and radiative characteristics of urban and rural surfaces as well as atmospheric parameters related to the general synoptic conditions were used as data input. In addition, buildings were modelled as parallelepipeds and the hysteresis of materials was taken into account. The model provides as output skin temperature of buildings, air temperature and humidity within the canopy layer and hence the mean surface temperature and the air temperature at 2 m above surface. The latter parameter was used for the comparison with in situ temperature observations. The model was applied to Rome in radiative summer and winter episodes. The results, which agree with observations, show that the Urban Heat Island (UHI) is a nocturnal phenomenon, present both in winter (the greatest difference between urban and rural temperatures is about 2 degrees C) and summer (the temperature difference is about 5 degrees C), mainly resulting from the urban geometry and the thermal properties of materials. The anthropogenic heat does not play an important role in the UHI development. A monthly nocturnal behaviour of temperature differences between urban and surrounding rural areas shows that the maximum mean value of 4.2 degrees C occurs in August. Moreover, the parks in the city centre, where temperatures are lower, define two distinct heat islands, east and west.

The crystal structures of Sinapis alba myrosinase and a covalent glycosyl-enzyme intermediate provide insights into the substrate recognition and active-site machinery of an S-glycosidase.

BACKGROUND: Myrosinase is the enzyme responsible for the hydrolysis of a variety of plant anionic 1-thio-beta-D-glucosides called glucosinolates. Myrosinase and glucosinolates, which are stored in different tissues of the plant, are mixed during mastication generating toxic by-products that are believed to play a role in the plant defence system. Whilst O-glycosidases are extremely widespread in nature, myrosinase is the only known S-glycosidase. This intriguing enzyme, which shows sequence similarities with O-glycosidases, offers the opportunity to analyze the similarities and differences between enzymes hydrolyzing S- and O-glycosidic bonds. RESULTS: The structures of native myrosinase from white mustard seed (Sinapis alba) and of a stable glycosyl-enzyme intermediate have been solved at 1.6 A resolution. The protein folds into a (beta/alpha)8-barrel structure, very similar to that of the cyanogenic beta-glucosidase from white clover. The enzyme forms a dimer stabilized by a Zn2+ ion and is heavily glycosylated. At one glycosylation site the complete structure of a plant-specific heptasaccharide is observed. The myrosinase structure reveals a hydrophobic pocket, ideally situated for the binding of the hydrophobic sidechain of glucosinolates, and two arginine residues positioned for interaction with the sulphate group of the substrate. With the exception of the replacement of the general acid/base glutamate by a glutamine residue, the catalytic machinery of myrosinase is identical to that of the cyanogenic beta-glucosidase. The structure of the glycosyl-enzyme intermediate shows that the sugar ring is bound via an alpha-glycosidic linkage to Glu409, the catalytic nucleophile of myrosinase. CONCLUSIONS: The structure of myrosinase shows features which illustrate the adaptation of the plant enzyme to the dehydrated environment of the seed. The catalytic mechanism of myrosinase is explained by the excellent leaving group properties of the substrate aglycons, which do not require the assistance of an enzymatic acid catalyst. The replacement of the general acid/base glutamate of O-glycosidases by a glutamine residue in myrosinase suggests that for hydrolysis of the glycosyl-enzyme, the role of this residue is to ensure a precise positioning of a water molecule rather than to provide general base assistance.

MECHANISMS IN ENDOCRINOLOGY: Endogenous subclinical hypercortisolism and bone: a clinical review.

In recent years, the condition of subclinical hypercortisolism (SH) has become a topic of growing interest. This is due to the fact that SH prevalence is not negligible (0.8-2% in the general population) and that, although asymptomatic, this subtle cortisol excess is not harmless, being associated with an increased risk of complications, in particular of osteoporosis and fragility fractures. As specific symptoms of hypercortisolism are absent in SH, the SH diagnosis relies only on biochemical tests and it is a challenge for physicians. As a consequence, even the indications for the evaluation of bone involvement in SH patients are debatable and guidelines are not available. Finally, the relative importance of bone density, bone quality and glucocorticoid sensitivity in SH is a recent field of research. On the other hand, SH prevalence seems to be increased in osteoporotic patients, in whom a vertebral fracture may be the presenting symptom of an otherwise asymptomatic cortisol excess. Therefore, the issue of who and how to screen for SH among the osteoporotic patients is widely debated. The present review will summarize the available data regarding the bone turnover, bone mineral density, bone quality and risk of fracture in patients with endogenous SH. In addition, the role of the individual glucocorticoid sensitivity in SH-related bone damage and the problem of diagnosing and managing the bone consequences of SH will be reviewed. Finally, the issue of suspecting and screening for SH patients with apparent primary osteoporosis will be addressed.

Expression of mouse PDGF-A and PDGF alpha-receptor genes during pre- and post-implantation development: evidence for a developmental shift from an autocrine to a paracrine mode of action.

We examined the expression of platelet-derived growth factor (PDGF)-A and the PDGF alpha-receptor in pre-implantation and early post-implantation mouse embryos. At two-cell and blastocyst stages, all cells express mRNA and protein for both ligand and receptor. In contrast, early post-implantation embryos express PDGF-A chain mRNA in both embryonic ectoderm and in the ectoderm lining the ectoplacental cavity, while mRNA for PDGF alpha-receptor is localized to the mesoderm layers of both embryonic and extra-embryonic membranes. At days 3.5 and 7.5, receptors are demonstrably functional in response to exogenous PDGF-AA. We propose that chronic autostimulation of PDGF alpha-receptors occurs in pre-implantation embryos, whereas, following implantation, early mesoderm development is dependent on stimulation by ectodermally produced PDGF-A.