Structure-based discovery of small molecule inhibitors targeted to protein tyrosine phosphatase 1B

Protein tyrosine phosphatases (PTPases) are involved in the control of tyrosine phosphorylation levels in the cell and are believed to be crucial for the regulation of a multitude of cellular functions. A detailed understanding of the role played by PTPases in various signaling pathways has not yet been achieved, and potent and selective PTPase inhibitors are essential in the quest to determine the functionality of individual PTPases. Using the DOCK methodology, we have carried out a structure-based, computer-assisted search of an available chemical database in order to identify low molecular weight, nonpeptidic PTP1B inhibitors. We have identified several organic molecules that not only possess inhibitory activity against PTP1B but which also display significant selectivity for PTP1B. This indicates that although structural features important for pTyr recognition are conserved among different PTPases, it is possible to generate selective inhibitors targeted primarily to the catalytic site. Kinetic analysis and molecular modeling experiments suggest that the PTP1B active site possesses significant plasticity such that substituted and extended aromatic systems can be accommodated. The newly identified molecules provide a molecular framework upon which therapeutically useful compounds can ultimately be based, and systematic optimization of these lead compounds is likely to further enhance their potency and selectivity.

Calpain inhibitor I increases beta-amyloid peptide production by inhibiting the degradation of the substrate of gamma-secretase. Evidence that substrate availability limits beta-amyloid peptide production

The calpain inhibitor N-acetyl-leucyl-leucyl-norleucinal (ALLN) has been reported to have complex effects on the production of the beta-amyloid peptide (Abeta). In this study, the effects of ALLN on the processing of the amyloid precursor protein (APP) to Abeta were examined in 293 cells expressing APP or the C-terminal 100 amino acids of APP (C100). In cells expressing APP or low levels of C100, ALLN increased Abeta40 and Abeta42 secretion at low concentrations, decreased Abeta40 and Abeta42 secretion at high concentrations, and increased cellular levels of C100 in a concentration-dependent manner by inhibiting C100 degradation. Low concentrations of ALLN increased Abeta42 secretion more dramatically than Abeta40 secretion. ALLN treatment of cells expressing high levels of C100 did not alter cellular C100 levels and inhibited Abeta40 and Abeta42 secretion with similar IC50 values. These results suggest that C100 can be processed both by gamma-secretase and by a degradation pathway that is inhibited by low concentrations of ALLN. The data are consistent with inhibition of gamma-secretase by high concentrations of ALLN but do not support previous assertions that ALLN is a selective inhibitor of the gamma-secretase producing Abeta40. Rather, Abeta42 secretion may be more dependent on C100 substrate concentration than Abeta40 secretion.

Spontaneous oligomerization of a staphylococcal alpha-hemolysin conformationally constrained by removal of residues that form the transmembrane beta-barrel

Staphylococcal alpha-hemolysin is a water soluble, monomeric, bacterial exotoxin, which forms heptameric pores in membranes. The rate determining step in assembly is the conversion of a heptameric prepore to the fully assembled pore in which the central glycine-rich domain of each subunit inserts into the membrane to form a 14 strand beta barrel. Barrel formation is accompanied by a conformational change in which each N terminus latches onto an adjacent subunit. In the monomer in solution, the central domain is loosely organized and exposed to solvent. In this study, 25 amino acids of the central domain were removed and replaced with the sequence Asp-Gly, which favors the formation of a type I' beta-turn, to yield a mutant devoid of hemolytic activity. Within minutes after synthesis in the absence of membranes, the mutant polypeptide spontaneously assembled into heptamers, as demonstrated by atomic force microscopy. Limited proteolysis suggested that the N termini of the subunits in the heptamers were in the fully assembled pore conformation rather than the prepore conformation. Based on these findings, the deletion is proposed to constrain the central domain and thereby force the creation of a shortened beta barrel, which in turn induces the additional structural changes that normally accompany pore formation. The truncated pore might make a useful framework for the construction of designed membrane active macromolecules.

Lymphocytes are important in early atherosclerosis

Lymphocytes represent a potentially important proinflammatory cell that localizes to atherosclerotic lesions. To determine whether they contribute to lesion development, atherosclerosis-prone (LDLR(-/-)) mice were crossed with lymphocyte-deficient (RAG1(-/-)) mice to generate double knockout progeny. After 8 weeks on a Western-type diet (WTD), lesion development was reduced by 54% in double knockout mice, as compared with matched LDLR(-/-) controls. However, these significant differences in lesion area gradually subsided as the WTD was continued for 12 and 16 weeks. Consistent with this observation, histological studies determined that lesion initiation and early progression were delayed in RAG1/LDL-R double knockout mice. Differences in lesion area did not correlate with any significant alterations in plasma lipid levels. These studies suggest that lymphocytes play an important role early in atherogenesis.

MiR-26b modulates insulin sensitivity in adipocytes by interrupting the PTEN/PI3K/AKT pathway

BACKGROUND

MicroRNAs (miRNAs) have emerged as epigenetic regulators of metabolism and energy homeostasis. There is a growing body of evidence pointing to miRNAs that have important regulatory roles in insulin sensitivity.

OBJECTIVE

The aim of this work was to explore the expression and mechanism of action of miR-26b in obesity-related insulin resistance (IR) in adipocytes.

METHODS

Quantitative real-time PCR was performed to determine miR-26b expression in obese rodent models, human obesity subjects and insulin-resistant adipocytes. We analysed the roles of miR-26b overexpression and inhibition on glucose uptake in adipocytes. Western blotting was used to detect the levels of protein molecules involved in the phosphoinositide-3-kinase (PI3K) pathway. Bioinformatics and the Dual Luciferase Assay were used to identify the target gene of miR-26b. We assessed the regulatory roles of miR-26b on the phosphatase and tensin homologue (PTEN)/PI3K/AKT pathway and the relationship between miR-26b and the metabolism of human obese subjects.

RESULTS

Levels of miR-26b are reduced in visceral adipose tissue (VAT) in obese rodent models, human obesity and insulin-resistant adipocytes. MiR-26b promotes insulin-stimulated glucose uptake and increases insulin-stimulated glucose transporter type 4 translocation to the plasma membrane in human mature adipocytes. MiR-26b modulates insulin-stimulated AKT activation via inhibition of its target gene, PTEN, and significantly increases insulin sensitivity via the PTEN/PI3K/AKT pathway. The expression level of miR-26b negatively correlates with increasing body mass index and homeostasis model assessment for IR in human obese subjects.

CONCLUSION

Decreased miR-26b expression in VAT may be involved in obesity-related IR by interrupting the PTEN/PI3K/AKT pathway.

Poly(N-isopropylacrylamide)-g-poly(ethyleneoxide) for high resolution and high speed separation of DNA by capillary electrophoresis

A new separation medium, poly(N-isopropylacrylamide)-g-poly(ethyleneoxide) (PNI-PAM-g-PEO) solution, used for double-stranded (ds) DNA separation by capillary electrophoresis (CE) is presented. This type of grafted copolymer has a good self-coating ability for quartz capillary tubing and a slightly temperature-dependent viscosity-adjustable property, making it easier to use. One bp resolution was achieved within 12.5 min by using 8% w/v PNIPAM-gPEO in 1 x TBE (Tris-borate-ethylenediaminetetraaceticacid) buffer with an effective column length of 10 cm and an applied electric field strength of 200 V/cm. The PNIPAM-g-PEO solutions had a high sieving ability for relatively small sized DNAs with the relative standard derivation for the first 10 runs being less than 0.9% by using the same polymer solution. With 8% w/v PNIPAM-g-PEO solution in a 1.5 cm column and 2400 V as the running voltage, phiX174/HaeIII digest could be clearly separated within 24 s.

Cholinergic activation of phosphoinositide signaling is impaired in Alzheimer's disease brain

The function of the phosphoinositide signal transduction system was compared in membranes from Alzheimer's disease (AD) and control postmortem brain. [3H]Phosphatidylinositol hydrolysis was concentration-dependently stimulated by GTP[S] and this was 40% lower than controls in AD prefrontal cortical membranes. Carbachol induced a response greater than that of GTP[S] alone, and this response was impaired in AD by 45%. Differential analysis of the receptor-coupled and G-protein contributions to the responses indicated that the G-protein deficit in AD had a predominant influence on the lowered responses to cholinergic agonists. Similar deficits were observed in AD in the responses to five additional cholinergic agonists, including acetylcholine with three different acetylcholinesterase inhibitors. Deficits in stimulated phosphoinositide hydrolysis were regionally selective and these deficits did not correlate directly with reductions in choline acetyltransferase activity in AD tissues. These data demonstrate that in AD there is a brain region-selective, large impairment of cholinergic agonist-induced signal transduction mediated by the phosphoinositide system, which we speculate may impact on amyloid precursor protein processing.

Socio-economic disparities in maternal mortality in China between 1996 and 2006

OBJECTIVE

China's economic reforms have raised concerns over rising inequalities in maternal mortality, but it is not known whether the gap across socio-economic regions has increased over time.

DESIGN

A population-based, longitudinal, ecological correlation study.

SETTING

China.

SAMPLE

Records from the National Maternal and Child Mortality Surveillance System between 1996 and 2006.

METHODS

We report levels, causes and timing of maternal deaths, and examine crude and adjusted time trends in the overall and cause-specific maternal mortality ratio in five socio-economic regions (using Poisson regression). We examine whether socio-economic disparities have widened over time using concentration curves.

MAIN OUTCOME MEASURES

All-causes and cause-specific maternal mortality ratios.

RESULTS

Maternal mortality (MMR) declined by 6% per year (yearly rate ratio, RR, 0.94; 95% CI 0.93-0.96). The decline was most pronounced in the wealthiest rural type-I counties (RR 0.89; 95% CI 0.85-0.93), and in the poorest rural type-IV counties (RR 0.90; 95% CI 0.82-1.00). There were declines in almost all causes of maternal death. Postpartum haemorrhage (PPH) was by far the leading cause of maternal death (32%, 997/3164). The decline in MMR was largely explained by the increased uptake of institutional births. Concentration curves suggest that wealth-related regional inequalities did not increase over time.

CONCLUSIONS

China's extraordinary economic growth has not adversely affected disparities in MMR across socio-economic regions over time, but poor rural women remain at disproportionate risk. Other emerging economies can learn from China's focus on the supply and quality of maternity services along with more general health systems strengthening.

Improving the blood compatibility of polyurethane using carbon nanotubes as fillers and its implications to cardiovascular surgery

Blood compatibility has been an occlusion for biomaterials used in the cardiovascular system. In this work, a multiwalled carbon nanotubes-polyurethane composite (MWNT-PU) was prepared through a controlled co-precipitation. The surface chemical composition of treated carbon nanotubes was analyzed with XPS and the thermal behaviors of composite were characterized by DSC. The platelet adhesion and activation caused by the composite were evaluated by using SEM and flow cytometric analysis, respectively, and the disruption of red blood cells was analyzed through measuring the absorbance of free hemoglobin. The experimental results demonstrated that: (1) Multiwalled carbon nanotubes (MWNTs) with oxygen-containing functional groups could be well dispersed in polyurethane matrix through a controlled coprecipitation; (2) the composite surface displayed a significantly improved anticoagulant function, which can be indicative of the promising potentials of carbon nanotube-based materials in the implants and medical devices applied in blood-contacting environments.

Impaired phosphoinositide hydrolysis in Alzheimer's disease brain

The effect of Alzheimer's disease (AD) on the activity of the phosphoinositide second messenger system was studied by measuring the hydrolysis of [3H]phosphatidylinositol (PI) by membranes from postmortem human prefrontal cortex. The activity of phospholipase C was similar in AD and control tissue. Activation with GTP gamma S and with carbachol demonstrated less [3H]PI hydrolysis in AD than control membranes. The concentration of Gq/11, the G-proteins most likely functional in phosphoinositide metabolism, was unchanged in AD compared with controls, indicating that function of the receptor-G-protein complex rather than the G-protein concentration was the site of the impairment in AD. These results indicate that postsynaptic muscarinic receptor responses are impaired in AD, a finding that may explain, in part, the limited therapeutic responses achieved by administration of cholinomimetics to patients with AD. Also, this assay provides a means to identify cholinomimetics that are most effective in activating muscarinic receptor-coupled phosphoinositide hydrolysis in human brain, agents which should have the greatest potential for providing therapeutic responses in AD.

Mesenchymal stem cell-based cartilage tissue engineering: cells, scaffold and biology

Cartilage repair and regeneration by stem cell-based tissue engineering could be of enormous therapeutic and economic potential benefit for an aging population. However, to use stem cells effectively, their natural environment must be understood in order to expand them in vitro without compromising their multilineage potential and their specific differentiation program. Collaboration between diverse academic disciplines and between research and regulatory government agencies and industry is crucial before cell-based cartilage tissue engineering can achieve its full therapeutic potential.

Infection of cord blood monocyte-derived macrophages with human immunodeficiency virus type 1

We have investigated the susceptibility of cord blood monocyte-derived macrophages to human immunodeficiency virus type 1 (HIV-1) infection in vitro. Cord blood monocytes were maintained in vitro for 10 to 15 days and then infected with HIV-1. Syncytia were observed 14 days after infection by light microscopy. Viral proteins were detected by immunofluorescence assay. Electron microscopic examination demonstrated typical lentivirus particles within cytoplasmic vacuoles. The supernatants from the HIV-1-infected cultures also contained significant reverse transcriptase activity and p24 antigen. Like adult monocyte/macrophages, cord-derived monocyte/macrophages expressed the CD4 receptor molecule. Pretreatment with blocking antibody prior to infection with HIV-1 Bal significantly reduced or blocked infection of cord monocyte/macrophages. When cord and adult monocyte/macrophages were infected with HIV-1 Bal or Ada-M and directly compared, higher reverse transcriptase activities and p24 antigen expression were obtained with cord monocyte/macrophages. However, no significant difference was found between adult and cord monocyte/macrophages infected with HIV-1 IIIB. These observations suggest that cord monocyte-derived macrophages may be important in the pathogenesis of pediatric AIDS and that the increased susceptibility of cord monocyte/macrophages to HIV-1 infection in vitro may be relevant to the enhanced susceptibility of neonates to HIV-1 diseases in vivo.

Study of dyadic communication in couples managing prostate cancer: a longitudinal perspective

OBJECTIVE

Cancer patients and partners often report inadequate communication about illness-related issues, although it is essential for mutual support and informal caregiving. This study examined the patterns of change in dyadic communication between patients with prostate cancer and their partners, and also determined if certain factors affected their communication over time.

METHOD

Using multilevel modeling, this study analyzed longitudinal data obtained from a randomized clinical trial with prostate cancer patients and their partners, to examine their communication over time. Patients and partners (N=134 pairs) from the usual-care control group independently completed baseline demographic assessment and measures of social support, uncertainty, symptom distress, and dyadic communication at baseline, and 4-, 8-, and 12-month follow-ups.

RESULTS

The results indicated that (1) patients and partners reported similar levels of open communication at the time of diagnosis. Communication reported by patients and partners decreased over time in a similar trend, regardless of phase of illness; (2) phase of illness affected couples' open communication at diagnosis but not patterns of change over time; and (3) couples' perceived communication increased as they reported more social support, less uncertainty, and fewer hormonal symptoms in patients. Couples' demographic factors and general symptoms, and patients' prostate cancer-specific symptoms did not affect their levels of open communication.

CONCLUSIONS

Perceived open communication between prostate cancer patients and partners over time is affected by certain baseline and time-varying psychosocial and cancer-related factors. The results provide empirical evidence that may guide the development of strategies to facilitate couples' interaction and mutual support during survivorship.

Glucocorticoid downregulates expression of IL-12 family cytokines in systemic lupus erythematosus patients

OBJECTIVE

This study aims to investigate expression of interleukin 12 (IL-12) family cytokines IL-12, IL-23, IL-27 and IL-35 in systemic lupus erythematosus (SLE) patients and the effect of glucocorticoid (GC) treatment on their expression.

METHODS

Plasma concentration of IL-12, IL-23, IL-27, IL-35, IL-6 and anti-double-stranded DNA (dsDNA) antibodies in 30 newly diagnosed severe SLE patients and 30 matched healthy subjects was measured by enzyme-linked immunosorbent assay. The correlation between the levels of IL-12 family cytokines and the levels of IL-6 or anti-dsDNA antibodies was analyzed by Spearman rank correlation.

RESULTS

Significantly higher levels of plasma IL-12, IL-23, IL-27, IL-35, IL-6 and anti-dsDNA antibodies were observed in SLE patients compared with healthy controls (p < 0.05), and after prednisone treatment, the serum levels of IL-12 family cytokines decreased significantly. Moreover, serum levels of IL-12, IL-23, IL-27 and IL-35 were correlated with serum levels of IL-6 and anti-dsDNA antibodies in pre-treatment as well as post-treatment SLE patients.

CONCLUSIONS

SLE patients have increased plasma levels of IL-12 family cytokines and GCs can downregulate the expression of them in SLE patients. Therefore, members of the IL-12 family may be involved in the pathophysiological process of SLE.

Traditional karyotyping vs copy number variation sequencing for detection of chromosomal abnormalities associated with spontaneous miscarriage

OBJECTIVES

To compare the performance of traditional G-banding karyotyping with that of copy number variation sequencing (CNV-Seq) for detection of chromosomal abnormalities associated with miscarriage.

METHODS

Products of conception (POC) were collected from spontaneous miscarriages. Chromosomal abnormalities were detected using high-resolution G-banding karyotyping and CNV sequencing. Quantitative fluorescent polymerase chain reaction analysis of maternal and POC DNA for short tandem repeat (STR) markers was used to both monitor maternal cell contamination and confirm the chromosomal status and sex of the miscarriage tissue.

RESULTS

A total of 64 samples of POC, comprising 16 with an abnormal and 48 with a normal karyotype, were selected and coded for analysis by CNV-Seq. CNV-Seq results were concordant for 14 (87.5%) of the 16 gross chromosomal abnormalities identified by karyotyping, including 11 autosomal trisomies and three sex chromosomal aneuploidies (45,X). Of the two discordant results, a 69,XXX polyploidy was missed by CNV-Seq, although supporting STR marker analysis confirmed the triploidy. In contrast, CNV-Seq identified a sample with 45,X karyotype as a 45,X/46,XY mosaic. In the remaining 48 samples of POC with a normal karyotype, CNV-Seq detected a 2.58-Mb 22q deletion associated with DiGeorge syndrome and nine different smaller CNVs of no apparent clinical significance.

CONCLUSIONS

CNV-Seq used in parallel with STR profiling is a reliable and accurate alternative to karyotyping for identifying chromosome copy number abnormalities associated with spontaneous miscarriage.

Interaction of chloroquine with linear and supercoiled DNAs. Effect on the torsional dynamics, rigidity, and twist energy parameter

The magnitude and uniformity of the torsion elastic constant (alpha) of linear pBR322 DNA and supercoiled pBR322 DNAs with high-twist (sigma = -0.083) and normal-twist (sigma = -0.48) are measured in 0.1 M NaCl as a function of added chloroquine/base-pair ratio (chl/bp) by studying the fluorescence polarization anisotrophy (FPA) of intercalated ethidium dye. The time-resolved FPA is measured by using a picosecond dye laser for excitation and time-correlated single-photon counting detection. A general theory is developed for the binding of ligands that unwind superhelical DNAs, and the simultaneous binding of two different intercalators is treated in detail. The equilibrium constant (K) for binding chloroquine to linear pBR322 DNA and the number (r) of bound chloroquines per base pair are determined from the relative amplitude ratio of the slow (normally intercalated) and fast (free) components in the decay of the (probe) ethidium fluorescence intensity as a function of chl/bp. For chloroquine binding to supercoiled pBR322 DNAs, the intrinsic binding constant is assumed to be the same as for the linear DNA, but the twist energy parameter ET (N times the free energy to change the linking number from 0 to 1 in units of kBT) is regarded as adjustable. Using the best-fit ET, the binding ratios r are calculated for each chl/bp ratio. Twist energy parameters are also determined for ethidium binding to these supercoiled DNAs by competitive dialysis. For chloroquine binding, we obtain ET = 360 and 460 respectively for the normal-twist and high-twist supercoiled DNAs. For ethidium binding the corresponding values are ET = 280 +/- 70 and 347 +/- 50. Like other dye-binding values, these are substantially lower than those obtained by ligation methods. In the absence of chloroquine, the torsion constants of all three DNAs are virtually identical, alpha = (5.0 +/- 0.4) x 10(-12) dyn.cm. For linear pBR322 DNA, the magnitude and uniformity of alpha remain unaltered by intercalated chloroquine up to r = 0.19. This finding argues that the FPA is not significantly relaxed by diffusion of any kinks or solitons. If alpha d denotes the torsion constant between a dye and a base pair and alpha 0 that between two base pairs, then our data imply that alpha d/alpha 0 lies in the range 0.65-1.64, with a most probable value of 1.0.(ABSTRACT TRUNCATED AT 400 WORDS)

Gadd45 proteins as critical signal transducers linking NF-kappaB to MAPK cascades

The growth arrest and DNA damage-inducible 45 (Gadd45) proteins are a group of critical signal transducers that are involved in regulations of many cellular functions. Accumulated data indicate that all three Gadd45 proteins (i.e., Gadd45alpha, Gadd45beta, and Gadd45gamma) play essential roles in connecting an upstream sensor module, the transcription Nuclear Factor-kappaB (NF-kappaB), to a transcriptional regulating module, mitogen-activated protein kinase (MAPK). This NF-kappaB-Gadd45(s)-MAPK pathway responds to various kinds of extracellular stimuli and regulates such cell activities as growth arrest, differentiation, cell survival, and apoptosis. Defects in this pathway can also be related to oncogenesis. In the first part of this review, the functions of Gadd45 proteins, and briefly NF-kappaB and MAPK, are summarized. In the second part, the mechanisms by which Gadd45 proteins are regulated by NF-kappaB, and how they affect MAPK activation, are reviewed.

Activity-guided isolation of constituents of Tephrosia purpurea with the potential to induce the phase II enzyme, quinone reductase

An isoflavone, 7,4'-dihydroxy-3',5'-dimethoxyisoflavone (1), and a chalcone, (+)-tephropurpurin (2), both novel compounds, as well as six constituents of known structure, (+)-purpurin (3), pongamol (4), lanceolatin B (5), (-)-maackiain (6), (-)-3-hydroxy-4-methoxy-8,9-methylene-dioxypterocarpan (7), and (-)-medicarpin (8), were obtained as active compounds from Tephrosia purpurea, using a bioassay based on the induction of quinone reductase (QR) activity with cultured Hepa 1c1c7 mouse hepatoma cells. Additionally, three inactive compounds of known structure, 3'-methoxydaidzein, desmoxyphyllin B, and 3,9-dihydroxy-8-methoxycoumestan, were isolated and identified. The structure elucidation of compounds 1 and 2 was carried out by spectral data interpretation.

Gene mutation spectrum and genotype-phenotype correlation in a cohort of Chinese osteogenesis imperfecta patients revealed by targeted next generation sequencing

The achievement of more accurate diagnosis would greatly benefit the management of patients with osteogenesis imperfecta (OI). In this study, we present the largest OI sample in China as screened by next generation sequencing. In particular, we successfully identified 81 variants, which included 45 novel variants. We further did a genotype-phenotype analysis, which helps make a better understanding of OI.

INTRODUCTION

This study aims to reveal the gene mutation spectrum and the genotype-phenotype relationship among Chinese OI patients by next generation sequencing (NGS).

METHODS

We developed a NGS-based panel for targeted sequencing of all exons of 14 genes related to OI, and performed diagnostic gene sequencing for a cohort of 103 Chinese OI patients from 101 unrelated families. Mutations identified by NGS were further confirmed by Sanger sequencing and co-segregation analysis.

RESULTS

Of the 103 patients from 101 unrelated OI families, we identified 79 mutations, including 43 novel mutations (11 frameshift, 17 missense, 5 nonsense, 9 splice site, and 1 chromosome translocation) in 90 patients (87.4%). Mutations in genes encoding type I collagen, COL1A1 (n = 37), and COL1A2 (n = 29) accounts for 73.3% of all molecularly diagnosed patients, followed by IFITM5 (n = 9, 10%), SERPINF1 (n = 4, 4.4%), WNT1 (n = 4, 4.4%), FKBP10 (n = 3, 3.3%), TMEM38B (n = 3, 3.3%), and PLOD2 (n = 1, 1.1%). This corresponds to 75 autosomal dominant inherited (AD) OI patients and 15 autosomal recessive (AR) inherited patients. Compared with AD inherited OI patients, AR inherited patients had lower bone mineral density (BMD) at spine (P = 0.05) and less frequent blue sclera (P = 0.001). Patients with type I collagen qualitative defects had lower femoral neck BMD Z-score (P = 0.034) and were shorter compared with patients with type I collagen quantitative defects (P = 0.022).

CONCLUSION

We revealed the gene mutation spectrum in Chinese OI patients, and novel mutations identified here expanded the mutation catalog and genotype and phenotype relationships among OI patients.

Sex differences in umbilical cord serum levels of inhibin, testosterone, oestradiol, dehydroepiandrosterone sulphate, and sex hormone-binding globulin in human term neonates

The contribution of the fetus to inhibin production in human pregnancy is unclear. Previous studies have reported inhibin concentrations in cord blood but on limited sample numbers. The present study is a more extensive examination of sex differences in immunoreactive inhibin and steroidal hormones in term umbilical cord blood. Venous serum concentrations of inhibin were found to be significantly higher in males (mean +/- SD 2,168 +/- 914 pg/ml, n = 62) than in females (1,761 +/- 951 pg/ml, n = 63) (p < 0.01). Male concentrations of total testosterone (p < 0.005), free testosterone (p < 0.005), and estradiol (p < 0.05) were also significantly higher. The concentration of dehydroepiandrosterone sulphate (DHEAS) and the sex hormone-binding globulin (SHBG) capacity were similar in males and females. Multivariate regression analysis showed that the inhibin concentration in males correlated with the testosterone concentration and in females it correlated not only with testosterone concentration but also with gestational age at delivery and SHBG capacity (all p < 0.001). Inhibin concentrations in cord arterial serum in a subgroup of 24 males and 31 females were higher than in the venous serum in both sexes but the differences were not statistically significant. Concentrations of DHEAS determined in 22 female cord arterial blood samples (6.0 +/- 2.5 mumol/l) were significantly higher than the venous concentrations (5.2 +/- 1.8 mumol/l) (p < 0.05). Inhibin did not correlate with DHEAS either in their arterial serum concentrations or in the arteriovenous concentration differences. The findings of this study are consistent with the placenta being the principal source of inhibin circulating in the human fetus in late pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium- and pH-dependent aggregation of carboxypeptidase E

Carboxypeptidase E (CPE) is involved with the biosynthesis of numerous peptide hormones and neurotransmitters. Several forms of CPE have been previously detected in neuroendocrine cells, including a form which is soluble at pH 5.5 (S-CPE), a form which can be extracted from membranes with 1 M NaCl at pH 5.5 (M1-CPE), and a form which requires both 1% Triton X-100 and 1 M NaCl for extraction from membranes at pH 5.5 (M2-CPE). Like other peptide processing enzymes, CPE is known to be sorted into peptide-containing secretory vesicles of the regulated pathway. One mechanism that has been proposed to be important for sorting of regulated pathway proteins is Ca2+ and pH-induced aggregation. CPE purified from bovine pituitary membranes aggregates at pH 5.5 when the concentration of CPE is 0.3 micrograms/microliters or higher, but not when the concentration is 0.01 microgram/microliters. Aggregation of CPE is pH-dependent, with very little aggregation occurring at pH 6 or above. At pH 5.0-5.5, the M2 form of CPE shows a greater tendency to aggregate than the other two forms. At pH 6, Ca2+ concentrations from 1-30 mM increase the aggregation of M1- and M2-CPE, but not S-CPE. The aggregation of M2-CPE does not explain the apparent membrane binding of this protein since the aggregate is solubilized by 1% Triton X-100 at pH 5.5 or by pH 6.0, whereas M2-CPE is not extracted from membranes under these conditions. Taken together, these results are consistent with a model in which the decreasing pH and increasing Ca2+ levels in the trans Golgi network induce the aggregation of CPE, which contributes to the sorting of this protein into regulated pathway secretory vesicles.