Plasma amyloid-ß oligomers level is a biomarker for Alzheimer's disease diagnosis.

Amyloid beta (Aß), especially Aß oligomers, is important in Alzheimer's disease (AD) pathogenesis. We studied plasma Aß(40), Aß(42), and Aß oligomers levels in 44 AD patients and 22 non-demented controls. Cognitive functions were assessed by Chinese version of mini-mental state examination (MMSE), Abbreviated Metal Test (AMT), Alzheimer's Disease Assessment Scale Cognitive Subscale (ADAS-cog). Plasma Aß monomers and oligomers levels were measured by ELISA. We found that the median plasma Aß(40) and Aß(42) levels were similar between AD and controls, and without significant correlation with cognition. Plasma Aß oligomers level was higher in AD than controls (642.54 ng/ml [range 103.33-2676.93] versus 444.18 ng/ml [range 150.19-1311.18], p=0.047), and negatively correlated with cognition. In multivariate logistic regression analysis, the highest tertile of Aß oligomers levels showed an increased risk of AD than the combined group of middle and lowest tertiles (OR=8.85, p=0.013), after adjustment of gender, age and APOE4 genotype. Increased plasma Aß oligomers level was associated with decreased MMSE and AMT scores (p=0.037, p=0.043, respectively) and increased ADAS-cog score (p=0.036), suggesting negative correlation with cognitive function. We concluded that plasma Aß oligomers level is an useful biomarker for AD diagnosis.

Detection of endocrine disruptors - from simple assays to whole genome scanning.

Endocrine disruptors frequently bear little structural relationship to the hormone whose actions they disrupt. Consequently, the threat of an uninvestigated chemical cannot easily be assessed. Here three different approaches to assessment are discussed. The first presumes an endocrine-disrupting property, following which a cell model capable of responding to such a hormone is used. Although simple and cheap, it provides limited data. A second approach involves multiple assays to detect multiple hormones. Increasing the amount of data increased the difficulty in assessing the significance of results. To meet this problem, cluster analysis based on a simple mathematical matrix was adopted. The matrix was used to determine (i) a limited number of assays to identify a maximum number of endocrine disruptors and (ii) the chemicals with the most wide-ranging effects. A third approach was a whole genome expression analysis based on expression of mRNAs in human TE671 medulloblastoma cells. Expression of individual mRNAs was assessed using the Affymetrix GeneChip(®) Human Genome U133 Plus 2.0 chip. The significance of differential expressed genes was assessed based on gene ontology and pathways analyses using DAVID and GenMaPP programs. The results illustrated the very wide-ranging effects of these chemicals across the genome.

Communication between ephrinB2 and EphB4 within the osteoblast lineage.

Members of the ephrin and Eph family are local mediators of cell function through largely contact-dependent processes in development and in maturity. Production of ephrinB2 mRNA and protein are increased by PTH and PTHrP in osteoblasts. Both a synthetic peptide antagonist of ephrinB2/EphB4 receptor interaction and recombinant soluble extracellular domain of EphB4 (sEphB4), which is an antagonist of both forward and reverse EphB4 signaling, were able to inhibit mineralization and the expression of several osteoblast genes involved late in osteoblast differentiation. The findings are consistent with ephrinB2/EphB4 signaling within the osteoblast lineage having a paracrine role in osteoblast differentiation, in addition to the proposed role of osteoclast-derived ephrinB2 in coupling of bone formation to resorption. This local regulation might contribute to control of osteoblast differentiation and bone formation at remodeling sites, and perhaps also in modeling.

Neuromyelitis optica-IgG in idiopathic inflammatory demyelinating disorders amongst Hong Kong Chinese.

BACKGROUND: Idiopathic inflammatory demyelinating disorders (IIDD) affect the central nervous system. In classical multiple sclerosis (CMS), brain, optic nerves [optic neuritis (ON)] and spinal cord [acute transverse myelitis (ATM)] are affected. In neuromyelitis optica (NMO), optic nerves and spinal cord are predominantly affected. NMO-IgG, an autoantibody targeting aquaporin-4, is a marker for NMO. We studied the frequency and clinical relevance of NMO-IgG seropositivity in IIDD patients. METHODS: Neuromyelitis optica-IgG was detected by indirect immunofluorescence using primate cerebellum. RESULTS: Neuromyelitis optica-IgG was detected in six of 10 NMO patients (60%), six of 10 idiopathic relapsing transverse myelitis (IRTM) patients (60%), two of nine idiopathic relapsing ON patients (22%), one of 11 patients (9%) having single ON attack, one of 30 CMS patients (3%), and none of patients having single ATM attack or controls. Comparing NMO-IgG seropositive (n = 12) with NMO-IgG seronegative (n = 8) patients having NMO or IRTM, NMO-IgG seropositivity was associated with a higher relapse rate in first 2 years, 1.5 and 0.6 attacks/year for seropositive and seronegative groups respectively (P = 0.006), and non-significant trend towards more severe ON and myelitis with poorer clinical outcome. CONCLUSION: Neuromyelitis optica -IgG facilitates diagnosis of NMO spectrum disorders. NMO-IgG seropositivity is associated with higher relapse rate in first 2 years.

Gluteal compartment syndrome following abdominal aortic aneurysm repair: a case report.

Compartment syndromes occur when the elevated tissue pressure within a confined limb's myofascial compartment exceeds capillary pressure, with subsequent neurovascular compromise. In order to reduce disability and the consequences of ensuring ischemia, it is essential for early recognition and intervention. This is more commonly recognized in the calf. We report an unusual case of gluteal compartment syndrome after abdominal aortic aneurysm (AAA) repair.

Effects of plasticisers and related compounds on the expression of the soluble form of catechol-O-methyltransferase in MCF-7 cells.

Previously we have shown that E2 down regulates S-COMT expression. Here the effects of four phthalate esters and 4-(tert-octyl)phenol on the intra-cellular levels of S-COMT and COMT activity were studied in MCF-7 cells as a measure of estrogenic activity of these compounds. The four phthalate esters caused significant reductions in both S-COMT protein and COMT activity levels. These effects were inhibited by the ERalpha receptor antagonist ICI182780. 4-(tert-octyl)phenol also caused reductions in these parameters, but the effects were not abolished by ICI182780. Assay of S-COMT protein levels represents a simple and convenient method of assessing the estrogenic potential of a compound.

Estrogenic phenol and catechol metabolites of PCBs modulate catechol-O-methyltransferase expression via the estrogen receptor: potential contribution to cancer risk.

Commercial PCB mixtures have been shown to induce liver tumors in female rats and this effect has been attributed to the effects of PCBs on estrogen metabolism. Catechol metabolites of PCBs are potent inhibitors of COMT activity and are likely to contribute significantly to reduced clearance of genotoxic catechol metabolites of estrogen. The effect of PCB metabolites on COMT expression in cultured cells was investigated to explore potential mechanisms by which PCB exposure alters catechol estrogen clearance. We hypothesize that estrogenic PCB metabolites may contribute to reduction of COMT expression via interaction with the estrogen receptor. To test this hypothesis, human MCF-7 cells were exposed to PCB analogues and the expression of COMT determined. Western blot analysis demonstrated that COMT protein levels were statistically significantly reduced by both the phenolic and the catechol compounds, an effect which was abolished by the anti-estrogen, ICI182780. The above suggests that COMT levels may be reduced by estrogenic PCB metabolites, via interactions between PCB metabolites and the ER. It supports the hypothesis that both phenolic and catechol metabolites of PCBs may contribute to PCB-mediated carcinogenesis through reduction of COMT levels and activities and subsequent reduction in clearance of endogenous and xenobiotic catechols.

Anomalous adenosine cyclic 3':5'-monophosphate responses to glucagon in patients with hepatocellular carcinoma.

Glucagon resistance has been reported in rat hepatoma models. We studied the responses to glucagon challenge in 35 patients with hepato-cellular carcinoma. They have increased cyclic AMP and decreased glucose responses to glucagon (2 mg) challenge when compared with normal controls. Possible explanations for increased cyclic AMP responses include special membrane properties of hepatoma cells and increased adrenergic stimulation of adenylate cyclase during hypoglycemia. Decreased glucose responses are most apparent in patients with overt hypoglycemia. This may be related to a number of postulates, including depleted glycogen store of liver, impaired glycogenolysis, fatty metamorphosis, or insulin-like activities secreted by hepatoma. In this study, the increased cyclic AMP responses do not support the postulation that glucagon receptors are damaged in hepatocellular carcinoma.

Uncoupling proteins: targets of endocrine disruptors?

The roles of uncoupling proteins (UCPs) are discussed. Particular attention has been paid to the roles of UCP2 to UCP5 as agents mediating thermogenesis, and to the concept of limited or "mild" uncoupling as a means of reducing oxidative stress. The role of the endocrine system, thyroid hormones and catecholamines, in regulating expression of UCPs is also discussed.

Knockdown of PTHR1 in osteosarcoma cells decreases invasion and growth and increases tumor differentiation in vivo.

Osteosarcoma (OS) is the most common cancer of bone. Parathyroid hormone (PTH) regulates calcium homeostasis and bone development, while the paracrine/autocrine PTH-related protein (PTHrP) has central roles in endochondral bone formation and bone remodeling. Using a murine OS model, we found that OS cells express PTHrP and the common PTH/PTHrP receptor (PTHR1). To investigate the role of PTHR1 signaling in OS cell behavior, we used shRNA to reduce PTHR1 expression. This only mildly inhibited proliferation in vitro, but markedly reduced invasion through collagen and reduced expression of RANK ligand (RANKL). Administration of PTH(1-34) did not stimulate OS proliferation in vivo but, strikingly, PTHR1 knockdown resulted in a profound growth inhibition and increased differentiation/mineralization of the tumors. Treatment with neutralizing antibody to PTHrP did not recapitulate the knockdown of PTHR1. Consistent with this lack of activity, PTHrP was predominantly intracellular in OS cells. Knockdown of PTHR1 resulted in increased expression of late osteoblast differentiation genes and upregulation of Wnt antagonists. RANKL production was reduced in knockdown tumors, providing for reduced homotypic signaling through the receptor, RANK. Loss of PTHR1 resulted in the coordinated loss of gene signatures associated with the polycomb repressive complex 2 (PRC2). Using Ezh2 inhibitors, we demonstrate that the increased expression of osteoblast maturation markers is in part mediated by the loss of PRC2 activity. Collectively these results demonstrate that PTHR1 signaling is important in maintaining OS proliferation and undifferentiated state. This is in part mediated by intracellular PTHrP and through regulation of the OS epigenome.

The characterization, regulation, and function of insulin receptors on osteoblast-like clonal osteosarcoma cell line.

The properties and regulation of insulin receptors on monolayers of cultured clonal osteoblastic rat osteosarcoma UMR-106 cells and human osteosarcoma U20S cells were studied. Confluent cultures of UMR-106 cells bound lactoperoxidase-labeled, HPLC-purified [125I]A-14-monoiodinated insulin in a reversible, saturable, and specific manner. Binding was related inversely to the incubation temperature. Prolonged period of steady-state binding was achieved at all temperatures studied. Competition curves demonstrated half-maximal inhibition of [125I]insulin binding at an unlabeled insulin concentration of about 1 nM. Scatchard analysis of the binding data was curvilinear, suggesting negative cooperativity, and revealed that UMR-106 osteoblasts contained about 87,000 receptor sites per cell according to a two-site model. Bound [125I]insulin dissociated from osteoblasts with a t1/2 of about 15 minutes at 22 degrees C. The dissociation curve was multiexponential, and the addition of native insulin accelerated the dissociation of intact but not degraded [125I]insulin. Preincubation with 125 nM insulin for 1 h induced 70% loss of binding sites and reduced total insulin bound by 30%. When monolayers were treated with the lysosomotropic agent chloroquine, a 40% increase in cell-associated radioactivity that could not be dissociable in fresh buffer was observed. The use of an energy depleter, sodium fluoride, completely inhibited the effects of chloroquine. Similar results were obtained for human osteosarcoma U20S cells except that the number of receptor sites was far less than that of UMR-106 cells. Insulin increased collagen synthesis at a half-maximal concentration of 1 nM. To conclude, cultured rat and human osteoblasts possess insulin receptors that exhibit kinetic properties and specificity similar to those of other insulin target cells. Receptor-bound insulin is internalized and degraded by a chloroquine-sensitive, energy-requiring reaction. Insulin receptor on bone cells modulates the synthesis of collagen and this role may be important in bone homeostasis.

Desensitization of parathyroid hormone receptors on cultured bone cells.

Administration of excessive amounts of parathyroid hormone (PTH) in the treatment of osteoporosis can reverse the beneficial effects of a low-dose, intermittent regime. To investigate the direct actions and the possible cellular mechanisms of PTH in inducing desensitization of PTH receptors, we studied the effects of desensitization on rat osteoblastic UMR-106 cells. When the osteoblasts were preincubated with bPTH-(1-34), complete refractoriness to a subsequent challenge with the hormone developed within 1 h and at hormone concentrations as low as 5 nM. When osteoblasts thus desensitized were incubated in hormone-free medium, recovery of the cAMP responses began within 2 h and reached maximum after 16 h. Cycloheximide did not affect the process of desensitization. [Nle8,Nle18,Tyr34]bPTH-(3-34)amide significantly impaired the desensitization process by PTH-(1-34) but did not have stimulatory effect on cAMP responses. No significant heterologous desensitization was obvious after preincubation with isoprenaline (50 microM), prostaglandin E1 (50 microM), or prostaglandin E2 (50 microM) for 2 h. Binding experiments with [125I]PLP-(1-36)amide after desensitization revealed that there was an approximate twofold decrease in receptor affinities as analyzed by Scatchard analysis, showing that the decrease in affinity was prominent in the process of desensitization. When the cells were treated with monensin during desensitization, PTH challenge after desensitization produced significantly lower cyclic AMP responses. Recovery after desensitization occurred over a period of 16 h. Inclusion of monensin, but not cycloheximide, impaired the recovery. The results show that homologous desensitization of rat osteoblasts to PTH is brought about by the occupancy of receptors by PTH-(1-34) but not by cAMP generation itself.(ABSTRACT TRUNCATED AT 250 WORDS)

Down-regulation of insulin receptors in postnecrotic cirrhosis of liver.

Eighteen patients with postnecrotic cirrhosis of liver, including three patients who had had a portosystemic shunt operation, and 19 normal controls were studied. The tests performed included monocyte insulin receptor assay, iv glucose tolerance test, glucagon test, and insulin tolerance test. Insulin resistance was documented by the presence of fasting hyperglycemia and glucose intolerance together with hyperinsulinemia as well as resistance to exogenous insulin. The binding of [125I]insulin to monocyte insulin receptors was significantly decreased in cirrhotic patients compared with that in controls (P less than 0.02), and this was due to a significant decrease in the high affinity association constant (P less than 0.005). There was a significant negative correlation between the fasting insulin level and maximum [125I]insulin binding in cirrhotic patients (r = -0.8; P less than 0.02). Cirrhotics that had had a shunt operation showed a higher fasting insulin level, a greater insulin resistance, and a smaller maximum [125I]insulin binding to insulin receptors than those without shunt. All of these findings suggested a down-regulatory effect of hyperinsulinemia on the monocyte insulin receptors. An impaired glycemic response to glucagon was also found in cirrhotics, the exact mechanism of which remains to be elucidated. However, as the increases in plasma cAMP after glucagon were similar in cirrhotics and controls, the fault apparently did not lie in the glucagon receptor.

The use of glucagon challenge tests in the diagnostic evaluation of hypoglycemia due to hepatoma and insulinoma.

We previously found that patients with hypoglycemia due to chronic renal and liver disease had anomalous metabolic responses to glucose and glucagon stimulation. In this study we evaluated the use of glucagon (2 mg, iv) tests in the diagnosis of spontaneous hypoglycemia secondary to hepatocellular carcinoma (HCC) and insulinoma. Twenty-one normal subjects, 45 patients with HCC (11 with hypoglycemia), and 14 patients with insulinoma (all with hypoglycemia) were studied. The fasting blood glucose level was low in all patients with hypoglycemia. The fasting plasma insulin and C-peptide concentrations were high in patients with insulinoma and low in patients with HCC and hypoglycemia. The blood glucose responses to glucagon administration were less than normal in patients with HCC and hypoglycemia and within normal limits in patients with insulinoma. The insulinoma patients had increased plasma insulin and C-peptide responses to glucagon despite having low blood glucose levels. Compared with the HCC patients without hypoglycemia, HCC patients with hypoglycemia had impaired plasma insulin and C-peptide responses. The fasting hypoglycemia, hypoinsulinemia, and impaired insulin/C-peptide responses to glucagon in patients with hepatoma and hypoglycemia presumably reflect the production of insulin-like substances by the hepatoma. We conclude that glucagon administration results in characteristic responses in these groups of patients and can be of use in the diagnosis of spontaneous hypoglycemia secondary to hepatoma or insulinoma.

Hypocalcemic and normocalcemic hyperparathyroidism in patients with advanced prostatic cancer.

PTH and ionized calcium levels were measured in 131 patients with advanced prostate cancer, all of whom had received at least first-line hormone therapy. Patients were classified into those in remission, those with stable disease, or those with progressive disease according to their prostate-specific antigen response and their clinical status. Thirty-four percent of all patients had PTH levels above the upper level of normal for controls of similar age (7.0 pmol/liter), and in 44% of these patients this was associated with a normal ionized calcium. Patients with proven bone metastases had significantly higher PTH levels than those without. (7.3 +/- 0.5 vs. 4.3 +/- 0.4 pmol/liter, P < 0.0005). There was evidence for a difference in the PTH levels between the three response groups. The PTH levels tended to be higher in patients with progressive disease. Thirty-seven of 65 patients (57%) with both progressive disease and proven bone metastases had elevated PTH levels. Mean levels of urinary deoxypyridinoline and cAMP were significantly greater in patients with high PTH than in those with a normal PTH. Treatment with oral calcium supplements in 32 patients with a high PTH seemed to have only a transient effect on elevated PTH or low ionized calcium levels. These data show that secondary hyperparathyroidism occurs frequently in patients with advanced prostate cancer, particularly in those with both progressive disease and bone metastases. The increased PTH levels are associated with an increase in bone resorption markers. These findings raise important questions about the role of PTH in progression of prostatic cancer in bone and the potential limitations of the use of bisphosphonates in patients with a raised PTH or low serum calcium.

Circulating PTH and PTHrP levels before and after treatment of tumor induced hypercalcemia with Pamidronate Disodium (APD).

The effect of lowering ionized calcium on circulating parathyroid hormone (PTH) and parathyroid hormone-related protein (PTHrP) was assessed in twenty patients with hypercalcemia of malignancy following treatment with Pamidronate Disodium. Ionized calcium levels fell rapidly in all treated patients. PTH concentrations were initially suppressed below normal in 18 patients, but rose from 0.48 +/- 0.42 pmol/L to 3.63 +/- 3.13 pmol/L (p less than 0.01) after treatment, reaching higher than normal values in some patients even in the presence of persistent hypercalcemia. PTHrP concentrations did not change significantly after treatment. These findings are consistent with an increased sensitivity of parathyroid tissue to changes in ionized calcium following prolonged exposure to hypercalcemia. Regulation of tumor secretion of PTHrP by calcium was not apparent within the range of calcium concentrations in this study.

Local secretion of parathyroid hormone-related protein by an osteoblastic osteosarcoma (UMR 106-01) cell line results in growth inhibition.

Parathyroid hormone-related protein (PTHrP) has been implicated as being important in the growth of tumor cells responsive to the peptide. We utilized a rat osteoblastic osteosarcoma cell line, UMR 106-01, which has PTHrP receptors and a PTHrP-responsive adenylate cyclase/cAMP messenger system, to produce a modified cell line that overexpresses PTHrP. The human PTHrP cDNA sequence was transfected by electroporation into UMR 106-01 cells and the stable cell lines UMR-36 and UMR-34 were established. The modified cell line, UMR-36, had increased levels of PTHrP mRNA compared with control cell lines and secreted PTHrP into the culture medium at levels of 0.01-0.1 pmol/10(7) cells in 12 h. The secreted peptide was biologically active as indicated by its ability to activate adenylate cyclase. The number of UMR-36 cells following 9 days in culture was reduced by up to 80% compared with control lines, which was associated with decreased (3)H-thymidine incorporation into genomic DNA. Addition of 1000-fold excess of the PTHrP antagonist, PTHrP(7-34), to UMR-36 cells resulted in the escape of growth inhibition and increased rate of growth. In vivo, tumors derived from UMR-36 cells were smaller in size compared with tumors derived from control cells. In conclusion, increased autocrine secretion of, and responsiveness to, PTHrP results in inhibited growth kinetics of an osteoblast-like bone tumor cell line in vitro and in vivo.

Vitamin D status among patients with fractured neck of femur in Hong Kong.

Vitamin D deficiency leads to secondary hyperparathyroidism initially and then to mild osteomalacia, both of which conditions may be aymptomatic and may predispose to bone fracture. To assess the importance of vitamin D deficiency in predisposing to fractured neck of femur, we studied the vitamin D status, dietary intake and socio-economic characteristics in 69 patients with fractured neck of femur (group A), 28 normal subjects with age above 60 (group B), and 101 normal volunteers (group C). Patients with fractured neck of femor had significantly lower levels of serum 25-hydroxy-cholecalciferol compared with subjects of groups B and C. There is no statistically significant difference in other biochemical parameters, including calcium, phosphate, and alkaline phosphatase. Patients with fractured neck of femur and with 25-hydroxycholecalciferol below 20 ng/mL were characterized by a home-bound and/or institutionalized life-style, smaller living place, and limited access to open space. To conclude, hypovitaminosis D is a common problem among elderly patients with fractured neck of femur in Hong Kong. The fact that such vitamin D deficiency is associated with muscle weakness may contribute to falls, and thus indirectly account for an increased rate of hip fractures over the normal control.

Angioneurotic edema, agranulocytosis, and fatal septicemia following captopril therapy.

Captopril, an angiotensin converting enzyme inhibitor used in the treatment of hypertension, has been associated with hematologic as well as dermatologic side effects. Two patients with captopril-induced angioneurotic edema, one of whom had fatal granulocytopenia and overwhelming polymicrobial sepsis, are presented.