Imbalanced circulating matrix metalloproteinases in polycystic ovary syndrome

Altered levels of matrix metalloproteinases (MMPs) may reflect relevant pathogenetic mechanisms of disease conditions. The objective of this study was to compare the plasma levels of MMPs and tissue inhibitors of MMPs (TIMPs) in polycystic ovary syndrome (PCOS) patients with those found in healthy ovulatory controls and to examine whether the levels of these biomarkers are associated with clinical and biochemical features of this syndrome. Sixty-five healthy ovulatory subjects (controls) and 80 patients with PCOS were include in this study. MMP-2, MMP-8, MMP-9, TIMP-1, TIMP-2 concentrations were measured in plasma samples by gelatin zymography or enzyme-linked immunoassays. MMP-2, MMP-8, MMP-9, and TIMP-1 levels were similar in PCOS patients and in healthy controls (P > 0.05). PCOS patients had lower plasma TIMP-2 levels than healthy controls (P < 0.05). We found higher MMP-2/TIMP-2 and MMP-9/TIMP-1 ratios in PCOS patients than in healthy controls (all P < 0.05). Testosterone levels correlated positively with the MMP-9/TIMP-1 ratio and negatively with TIMP-2 levels (r = 0.26, P < 0.01 and r = -0.21, P = 0.02, respectively). In addition, only testosterone was an independent predictor of TIMP-2 levels (estimate = -0.35, P = 0.04) and the MMP-9/TIMP-1 ratio (estimate = 0.01, P = 0.04). We found evidence indicating that the balance between MMPs and TIMPs in women with PCOS is altered, probably due to androgen excess found in these women.     

Evaluation of analogues of GalNAc as substrates for enzymes of the mammalian GalNAc salvage pathway

Changes in glycosylation are correlated to disease and associated with differentiation processes. Experimental tools are needed to investigate the physiological implications of these changes either by labeling of the modified glycans or by blocking their biosynthesis. N-Acetylgalactosamine (GalNAc) is a monosaccharide widely encountered in glycolipids, proteoglycans, and glycoproteins; once taken up by cells it can be converted through a salvage pathway to UDP-GalNAc, which is further used by glycosyltransferases to build glycans. In order to find new reporter molecules able to integrate into cellular glycans, synthetic analogues of GalNAc were prepared and tested as substrates of both enzymes acting sequentially in the GalNAc salvage pathway, galactokinase 2 (GK2) and uridylpyrophosphorylase AGX1. Detailed in vitro assays identified the GalNAc analogues that can be transformed into sugar nucleotides and revealed several bottlenecks in the pathway: a modification on C6 is not tolerated by GK2; AGX1 can use all products of GK2 although with various efficiencies; and all analogues transformed into UDP-GalNAc analogues except those with alterations on C4 are substrates for the polypeptide GalNAc transferase T1. Besides, all analogues that could be incorporated in vitro into O-glycans were also integrated into cellular O-glycans as attested by their detection on the cell surface of CHO-ldlD cells. Altogether our results show that GalNAc analogues can help to better define structural requirements of the donor substrates for the enzymes involved in GalNAc metabolism, and those that are incorporated into cells will prove valuable for the development of novel diagnostic and therapeutic tools.     

Complexity of agonist- and cyclic AMP-mediated downregulation of the human beta 1-adrenergic receptor: role of internalization,degradation, and mRNA destabilization

Prolonged agonist exposure often induces downregulation of G protein-coupled receptors (GPCRs). Although downregulation of the prototypical beta(2)-adrenergic receptor (beta(2)AR) has been extensively studied, the underlying mechanisms have yet to be resolved. As even less is known about the beta(1)-subtype, we investigated the downregulation of human beta(1)AR stably expressed in Chinese hamster fibroblasts in response to the agonist isoproterenol or the cell-permeable, chlorophenylthio-cAMP (CPT-cAMP). While either effector mediated decreases in both beta(1)AR binding activity and steady-state beta(1)AR mRNA levels, there were significant differences in their actions. Whereas agonist-mediated downregulation of beta(1)AR followed first-order kinetics, that induced by CPT-cAMP was delayed for several hours and approximately 50% of the former. Furthermore, agonist but not CPT-cAMP induced beta(1)AR internalization, and inhibiting internalization also suppressed agonist-mediated downregulation. The latter, however, was more sensitive than the former to agonist concentration (EC(50) of 0.3 vs 48 nM). Thus, at < or =1 nM agonist, downregulation occurred without internalization and with a pattern similar to that mediated by CPT-cAMP. The amounts of beta(1)AR downregulated or internalized were proportional to initial receptor levels but reached saturation at approximately 2 and 3 pmol/mg of protein, respectively. The fate of beta(1)AR protein during downregulation was determined by immunoblotting with anti-C-terminal antibodies. In agonist-treated cells, beta(1)AR protein disappeared with time and without any immunoreactive degradation products. Agonist-mediated downregulation of the human beta(1)AR appears to be a complex process that consists of both agonist- and cAMP-specific components. The former involves both receptor internalization and degradation whereas the latter involves a reduction in receptor mRNA.     

Prolonged niacin treatment leads to increased adipose tissue PUFA synthesis and anti-inflammatory lipid and oxylipin plasma profile

Prolonged niacin treatment elicits beneficial effects on the plasma lipid and lipoprotein profile that is associated with a protective CVD risk profile. Acute niacin treatment inhibits nonesterified fatty acid release from adipocytes and stimulates prostaglandin release from skin Langerhans cells, but the acute effects diminish upon prolonged treatment, while the beneficial effects remain. To gain insight in the prolonged effects of niacin on lipid metabolism in adipocytes, we used a mouse model with a human-like lipoprotein metabolism and drug response [female APOE*3-Leiden.CETP (apoE3 Leiden cholesteryl ester transfer protein) mice] treated with and without niacin for 15 weeks. The gene expression profile of gonadal white adipose tissue (gWAT) from niacin-treated mice showed an upregulation of the “biosynthesis of unsaturated fatty acids” pathway, which was corroborated by quantitative PCR and analysis of the FA ratios in gWAT. Also, adipocytes from niacin-treated mice secreted more of the PUFA DHA ex vivo. This resulted in an increased DHA/arachidonic acid (AA) ratio in the adipocyte FA secretion profile and in plasma of niacin-treated mice. Interestingly, the DHA metabolite 19,20-dihydroxy docosapentaenoic acid (19,20-diHDPA) was increased in plasma of niacin-treated mice. Both an increased DHA/AA ratio and increased 19,20-diHDPA are indicative for an anti-inflammatory profile and may indirectly contribute to the atheroprotective lipid and lipoprotein profile associated with prolonged niacin treatment.     

The number of vertebrate repeats can be regulated at yeast telomeres by Rap1-independent mechanisms

The number of telomeric DNA repeats at chromosome ends is maintained around a mean value by a dynamic balance between elongation and shortening. In particular, proteins binding along the duplex part of telomeric DNA set the number of repeats by progressively limiting telomere growth. The paradigm of this counting mechanism is the Rap1 protein in Saccharomyces cerevisiae. We demonstrate here that a Rap1-independent mechanism regulates the number of yeast telomeric repeats (TG(1-3)) and of vertebrate repeats (T(2)AG(3)) when TEL1, a yeast ortholog of the human gene encoding the ATM kinase, is inactivated. In addition, we show that a T(2)AG(3)-only telomere can be formed and maintained in humanized yeast cells carrying a template mutation of the gene encoding the telomerase RNA, which leads to the synthesis of vertebrate instead of yeast repeats. Genetic and biochemical evidences indicate that this telomere is regulated in a Rap1-independent manner, both in TEL1 and in tel1Delta humanized yeast cells. Altogether, these findings shed light on multiple repeat-counting mechanisms, which may share critical features between lower and higher eukaryotes.     

Low-molecular-weight compounds with anticoagulant activity from the scorpion <Emphasis Type="Italic">Heterometrus laoticus</Emphasis> venom

Low-molecular-weight compounds with anticoagulant activity were isolated from the scorpion Heterometrus laoticus venom. The determination of the structure of the isolated compounds by nuclear magnetic resonance and mass spectrometry showed that one of the isolated compounds is adenosine, and the other two are dipeptides leucyl-tryptophan and isoleucyl-tryptophan. The anticoagulant properties of adenosine, which is an inhibitor of platelet aggregation, is well known, but its presence in scorpion venom is shown for the first time. The ability of leucyl-tryptophan and isoleucyl-tryptophan to slow down blood clotting and their presence in scorpion venom are also established for the first time.     

The metalloprotease SepA governs processing of accumulation‐associated protein and shapes intercellular adhesive surface properties in Staphylococcus epidermidis

The otherwise harmless skin inhabitant Staphylococcus epidermidis is a major cause of healthcare‐associated medical device infections. The species' selective pathogenic potential depends on its production of surface adherent biofilms. The Cell wall‐anchored protein Aap promotes biofilm formation in S. epidermidis, independently from the polysaccharide intercellular adhesin PIA. Aap requires proteolytic cleavage to act as an intercellular adhesin. Whether and which staphylococcal proteases account for Aap processing is yet unknown. Here, evidence is provided that in PIA‐negative S. epidermidis 1457Δica, the metalloprotease SepA is required for Aap‐dependent S. epidermidis biofilm formation in static and dynamic biofilm models. qRT‐PCR and protease activity assays demonstrated that under standard growth conditions, sepA is repressed by the global regulator SarA. Inactivation of sarA increased SepA production, and in turn augmented biofilm formation. Genetic and biochemical analyses demonstrated that SepA‐related induction of biofilm accumulation resulted from enhanced Aap processing. Studies using recombinant proteins demonstrated that SepA is able to cleave the A domain of Aap at residue 335 and between the A and B domains at residue 601. This study identifies the mechanism behind Aap‐mediated biofilm maturation, and also demonstrates a novel role for a secreted staphylococcal protease as a requirement for the development of a biofilm.     

Factors associated with a low prevalence of exclusive breastfeeding during hospital stay in urban and semi-rural areas of southern Vietnam

Background

There is a paucity of data regarding risk factors associated with suboptimal breastfeeding practices in urbanized areas of low-middle income countries (LMICs).

Methods

Through a large prospective birth cohort, which enrolled 6706 infants in Vietnam between 2009 and 2013, we investigated the practice of exclusive breastfeeding during hospital stay in urban and semi-rural populations and aimed to identify factors associated with suboptimal breastfeeding practices. Univariate and multivariable logistic regression were performed to determine factors associated with not exclusive breastfeeding during hospital stay.

Results

Of 6076 mothers, 33% (2187) breastfed their infant exclusively before hospital discharge; 9% (364/4248) in urban and 74% (1823/2458) in semi-rural areas. Exclusive breastfeeding up to 4 months was recorded in 15% (959/6210) of participants; this declined to <?1% (56/6093) at 6 months. Delivery by Caesarean section (Odds Ratio [OR] 0.07; 95% Confidence Interval [CI] 0.04, 0.11 and OR 0.05; 95% CI 0.03, 0.08) and neonatal complications (OR 0.2; 95% CI 0.07, 0.47 and OR 0.25; 95% CI 0.14, 0.46) were common and highly significant risk factors associated with a lack of exclusive breastfeeding during hospital stay in urban and semi-rural settings, respectively.

Conclusions

To our knowledge, this is the first large-scale investigation aimed at identifying factors associated with exclusive breastfeeding during hospital stay in Vietnam. Breastfeeding promotion strategies should prioritize common risk factors in hospital, such as Caesarean section and neonatal complications, and other location specific factors associated with socioeconomics.