Potential role of fibroblast growth factor 21 in the deterioration of bone quality in impaired glucose tolerance.

PURPOSE: Findings on trabecular bone score (TBS), an index of bone quality, have been reported in prediabetes defined by impaired fasting glucose or HbA1c. Here, we assessed the bone mineral density (BMD) and TBS in prediabetes individuals with impaired glucose tolerance (IGT), and investigated the association of these bone parameters with serum levels of fibroblast growth factor 21 (FGF21), a hormone implicated in bone metabolism and with higher levels in IGT. METHODS: Chinese postmenopausal women aged 55-80 years, without diabetes, were recruited from the Hong Kong Cardiovascular Risk Factor Prevalence Study in 2016-2018. Normal glucose tolerance (NGT) was defined by fasting glucose < 5.6 mmol/L and 2-h plasma glucose (2hG) < 7.8 mmol/L, and IGT by 2hG 7.8-11 mmol/L. Serum levels of FGF21 and other bone metabolism regulators were measured. Insulin sensitivity was assessed by the Matsuda index. Independent determinants of TBS were evaluated using multivariable stepwise linear regression. RESULTS: 173 individuals with NGT and 73 with IGT were included. TBS was lower in those with IGT compared to those with NGT, while BMD was comparable. Individuals with IGT had significantly higher serum FGF21 levels, which in turn showed an independent inverse relationship with TBS, attenuated after inclusion of the Matsuda index. Serum FGF21 levels, however, did not correlate with BMD. CONCLUSION: Among Chinese postmenopausal women, bone quality was worse in IGT, despite comparable bone density. FGF21 levels showed a significant independent inverse relationship with TBS, partly attributed to insulin resistance. Whether FGF21 contributes to the impaired bone quality in IGT remains speculative.

PEGylated Biodegradable Polyesters for PGSS Microparticles Formulation: Processability, Physical and Release Properties.

BACKGROUND: Particles from Gas Saturated Solution (PGSS) is an emergent method that employs supercritical carbon dioxide (scCO2) to produce microparticles. It is suitable for encapsulating biologically active compounds including therapeutic peptides and proteins. Poly(lactide acid) (PLA) and/or poly(lactic-coglycolic acid) (PLGA) are the most commonly used materials in PGSS, due to their good processability in scCO2. Previous studies demonstrated that the properties of the microparticles can be modulated by adding polyethylene glycol (PEG) or tri-block PEGylated copolymers. OBJECTIVE: In the present work, the effect of the addition of biodegradable PEGylated di-block copolymers on the physical properties and drug release performance of microparticles prepared by PGSS technique was evaluated. METHOD: mPEG5kDa-P(L)LA and mPEG5kDa-P(L)LGA with similar molecular weights were synthesized and their behaviour, when exposed to supercritical CO2, was investigated. Different microparticle formulations, composed of a high (81%) or low (9%) percentage of the synthesized copolymers were prepared and compared in terms of particle size distribution, morphology, yield and protein release. Drug release studies were performed using bovine serum albumin (BSA) as a model protein. RESULTS: PEGylated copolymers showed good processability in PGSS without significant changes to the physical properties of the microparticles. However, the addition of PEG exerted a modulating effect on the microparticle drug dissolution behaviour, increasing the rate of BSA release as a function of its content in the formulation. CONCLUSION: This study demonstrated the feasibility of producing microparticles by using PEGylated di-block copolymers through a PGSS technique at mild operating conditions (low operating pressure and temperature).

Optimization of Melatonin Dissolution from Extended Release Matrices Using Artificial Neural Networking.

BACKGROUND: Efficacy of melatonin in treating sleep disorders has been demonstrated in numerous studies. Being with short half-life, melatonin needs to be formulated in extended-release tablets to prevent the fast drop of its plasma concentration. However, an attempt to mimic melatonin natural plasma levels during night time is challenging. METHODS: In this work, Artificial Neural Networks (ANNs) were used to optimize melatonin release from hydrophilic polymer matrices. Twenty-seven different tablet formulations with different amounts of hydroxypropyl methylcellulose, xanthan gum and Carbopol®974P NF were prepared and subjected to drug release studies. Using dissolution test data as inputs for ANN designed by Visual Basic programming language, the ideal number of neurons in the hidden layer was determined trial and error methodology to guarantee the best performance of constructed ANN. RESULTS: Results showed that the ANN with nine neurons in the hidden layer had the best results. ANN was examined to check its predictability and then used to determine the best formula that can mimic the release of melatonin from a marketed brand using similarity fit factor. CONCLUSION: This work shows the possibility of using ANN to optimize the composition of prolonged-release melatonin tablets having dissolution profile desired.

In vitro assessment of ultraviolet protection of coloured cotton knitted fabrics with different structures under stretched and wet conditions.

Clothing provides intrinsic ultraviolet (UV) protection that can be improved by colouration. However, the daily wearing condition can undermine the UV protection of coloured clothing wherein garments are stretched by body movement and/or wetted by perspiration of wearers. Knitwear is an indispensable clothing in summer, but its UV protection against wearing conditions lacks extensive study especially in a fabric structural approach. This article aimed at narrowing the research gap by focusing on the UV protection against stretch and wetness provided by various knitted fabric constructions incorporating the knit, tuck and miss stitches. The results show that the black knitted fabrics exhibit a significant reduction in the UV protection factor by 53% on average at a 10% stretch level. Knitted fabrics with miss stitches retained good UV protection even when the fabrics were stretched by 20% of its original dimensions.

A middle-aged man with increasing body fat.

A 51-year-old man was referred for evaluation of gradual increase in body fat over bilateral arms, chest and abdomen for 6 months. He was a non-smoker and he drank at least four bottles of beer daily since the age of 18. There was no significant past medical history or any family history of obesity or endocrine diseases. Physical examination showed localized large bulk of fat over the neck, both arms and mammary regions, abdomen, and back (Figs and ). The lower limbs and buttock were relatively spared. There was telangiectasia over the face and chest wall, but no palmar erythema nor finger clubbing. The liver span was normal, and the spleen tip was palpated 2 cm below the costal margin. Examination of the cardiovascular, respiratory and neurological system was normal. [Figure: see text] [Figure: see text] Blood tests showed thrombocytopenia (platelet 140 × 10(9) L(-1) [normal: 170-380 × 10(9) L(-1) ]) and liver function derangement (bilirubin 27 µmol L(-1) , ALP 298 U L(-1) , ALT 127 U L(-1) , AST 165 U L(-1) , GGT 1353 U L(-1) , albumin 33 g L(-1) and globulin 42 g L(-1) ). His clotting profile and renal functions were normal. His hepatitis B surface antigen was positive, but his HBV DNA was <60 copies per mL. Fasting glucose was 5.0 mmol L(-1) . HbA1c was 5.6%. His lipid profile was satisfactory with total cholesterol of 2.9 mmol L(-1) , triglycerides 1.0 mmol L(-1) , HDL-C 1.37 mmol L(-1) and LDL-C 1.1 mmol L(-1) . Ultrasound of the abdomen showed normal-sized liver with coarsened liver parenchymal echogenicity. The spleen was enlarged to 14 cm. This middle-aged man suffered from multiple symmetric lipomatosis and alcoholic liver disease. Dual-energy X-ray showed 1746 gm (40.1%), 1498 gm (32.8%) and 8322 gm (26.8%) fat over the left arm, right arm and trunk, respectively. The legs were unaffected with 1703 gm (19.4%) and 1627 gm (17.7%) fat over the left and right sides, respectively. The patient was advised to stop drinking and he declined surgical treatment.

Effect of insulin on the soluble receptor for advanced glycation end products (RAGE).

AIMS: The receptor for advanced glycation end products (RAGE) plays an important role in the pathogenesis of diabetic complications. RAGE transcript splicing generates a number of isoforms, including a full-length membrane-bound receptor and a soluble isoform, endogenous secretory RAGE (esRAGE). Soluble forms of the receptor (sRAGE) can also be formed by ectodomain shedding of the membrane-associated receptor. We have evaluated serum levels of sRAGE and esRAGE in Chinese patients with Type 1 diabetes and investigated the effect of insulin on the generation of esRAGE and sRAGE in vitro. METHODS: Serum sRAGE and esRAGE were measured by ELISA. The in vitro effect of insulin was investigated by incubating THP-1 macrophages with insulin and RAGE isoforms in cell lysate and conditioned media determined. RESULTS: In patients with diabetes, both serum esRAGE and sRAGE were significantly higher than in age-matched healthy subjects without diabetes. In vitro, insulin increased esRAGE and total RAGE isoform expression in cell lysate on a western blot, and reverse transcription-polymerase chain reaction showed an increase in esRAGE and full-length RAGE mRNA. This was accompanied by an increase in esRAGE and sRAGE in cell conditioned media. Pretreatment of THP-1 cells with a general metalloproteinase inhibitor GM6001 significantly reduced the production of sRAGE, suggesting that insulin also increased the cleavage of full-length cell surface RAGE to form sRAGE. CONCLUSIONS: Chinese patients with Type 1 diabetes have higher serum levels of esRAGE and sRAGE. In vitro, insulin not only increases both full-length RAGE and esRAGE expression, but can also stimulate the shedding of sRAGE from the membrane-bound receptor.

Folate conjugated phosphorylcholine-based polycations for specific targeting in nucleic acids delivery.

Folic acid has been investigated as a targeting ligand for imaging and therapeutic agent for over a decade; however, studies on its use in targeting of nonviral gene or nucleic acids delivery systems are sparse. This study assesses potential application of a new folic acid conjugate with aminomethacrylate-phosphoryl-choline based copolymer (DMAEMA-MPC-FA) as a targeting gene delivery vector. The folate-conjugated polymers produce colloidally stable polyplexes with a particle size <200 nm and demonstrate the ability to protect DNA from enzymatic degradation to a certain extent. In cells that overexpress folate receptors (MCF-7 and KB cultures), the conjugated systems show a folate-specific association and achieved significantly enhanced transfection efficiency, compared to the nonconjugated control, with a dramatically reduced nonspecific cellular association. The transfection enhancement is achieved without a corresponding increase in cellular association, suggesting that an internal cellular trafficking of folate-conjugated system may be altered, resulting in an increased transfection efficacy. In summary, a new folate-conjugated aminomethacrylate-phosphorylcholine copolymer is capable of forming colloidal complexes with DNA, modulating their specific cell uptake and improving the level of cell transfection in folate expressing cells.

Further characterization of ADAMTS-13 inactivation by thrombin.

BACKGROUND: The multimeric size and platelet-tethering function of von Willebrand factor (VWF) are modulated by the plasma metalloprotease, a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS-13). In vitro ADAMTS-13 is susceptible to proteolytic inactivation by thrombin. OBJECTIVES: In this study, we aimed to characterize the inactivation of ADAMTS-13 by thrombin and to assess its physiological significance. METHODS AND RESULTS: By N-terminal sequencing of cleavage products, and by mutagenesis, we identified the principal thrombin cleavage sites in ADAMTS-13 as R257 and R1176. Using a library of 76 thrombin mutants, we highlighted the functional importance of exosite I on thrombin in the proteolysis of ADAMTS-13. Proteolysis of ADAMTS-13 by thrombin caused an 8-fold reduction in its affinity for VWF that contributed to its loss of VWF-cleaving function. Intriguingly, thrombin-cleaved ADAMTS-13 both bound and proteolyzed a short recombinant VWF A2 domain substrate (VWF115) normally. Following activation of coagulation in normal plasma, endogenous ADAMTS-13, but not added ADAMTS-13, appeared resistant to coagulation-induced fragmentation. An estimation of the K(m) for ADAMTS-13 proteolysis by thrombin was appreciably higher than the physiological concentration of ADAMTS-13. This was corroborated by the comparatively low affinity of ADAMTS-13 for thrombin (K(D) 95 nM). CONCLUSIONS: Together, our data suggest that ADAMTS-13 is protected from rapid proteolytic inactivation by thrombin in normal plasma. Whether this remains the case under pathological situations involving elevated/sustained generation of thrombin remains unclear.

An active surveillance study of vancomycin-resistant Enterococcus in Queen Elizabeth Hospital, Hong Kong.

OBJECTIVE: To assess the rate of faecal vancomycin-resistant Enterococcus colonisation in high-risk patients in a regional hospital. DESIGN: Prospective observational surveillance study. SETTING: Queen Elizabeth Hospital, Hong Kong. PATIENTS: From September 2001 to December 2002, stool samples from patients in the intensive care unit and patients in whom Clostridium difficile testing was requested were used for study using a broth enrichment method. MAIN OUTCOME MEASURES: Number of faecal vancomycin-resistant Enterococcus colonisation. RESULTS: A total of 2414 cultures from 1792 patients were tested for vancomycin-resistant Enterococcus using a broth enrichment method. Only one (0.06%) patient was found to harbour a vancomycin-resistant Enterococcus faecalis in the gastro-intestinal tract. Surveillance cultures from contacts of the case revealed another six with vancomycin-resistant Enterococcus faecalis. Vancomycin-resistant Enterococcus faecalis was also later reported from a clinical specimen (catheterized urine) of another patient. They were all epidemiologically linked to the index case. Mean inhibitory concentrations of vancomycin and teicoplanin were determined to be higher than 256 and 0.5 microgram/mL, respectively by E-test for all the vancomycin-resistant Enterococcus isolates. Polymerase chain reaction analysis confirmed the presence of vanB genes and the result was in line with the phenotype. Pulsed-field gel electrophoresis confirmed a monoclonal vancomycin-resistant Enterococcus outbreak. Strict infection control measures recommended by the Centers for Disease Control and Prevention were followed and the outbreak was successfully controlled. CONCLUSION: Vancomycin-resistant Enterococcus colonisation is rare, but present among high-risk patients in our hospital. A routine surveillance programme should be implemented that will enable early case detection and prompt initiation of infection control measures to prevent the emergence of an endemic situation.

Structural study of DNA condensation induced by novel phosphorylcholine-based copolymers for gene delivery and relevance to DNA protection.

Poly[2-(dimethylamino)ethyl methacrylate-b-2-methacryloyloxyethyl phosphorylcholine] (DMA-MPC) is currently under investigation as a new vector candidate for gene therapy. The DMA block has been previously demonstrated to condense DNA effectively. The MPC block contains a phosphorylcholine (PC) headgroup, which can be found naturally in the outside of the cell membrane. This PC-based polymer is extremely hydrophilic and acts as a biocompatible steric stabilizer. In this study, we assess in detail the morphologies of DNA complexes obtained using the diblock copolymer series DMA(x)MPC30 (where the mean degree of polymerization of the MPC block was fixed at 30 and the DMA block length was systematically varied) using transmission electron microscopy (TEM) and liquid atomic force microscopy (AFM). Both techniques indicate more compact complex morphologies (more efficient condensation) as the length of the cationic DMA block increases. However, the detailed morphologies of the DMA(x)MPC30-DNA complexes observed by TEM in vacuo and by AFM in aqueous medium are different. This phenomena is believed to be related to the highly hydrophilic nature of the MPC block. TEM studies revealed that the morphology of the complexes changes from loosely condensed structures to highly condensed rods, toroids, and oval-shaped particles as the DMA moiety increases. In contrast, morphological changes from plectonemic loops to flower-like and rectangular block-like structures, with an increase in highly condensed central regions, are observed by in situ AFM studies. The relative population of each structure is clearly dependent on the polymer molecular composition. Enzymatic degradation assays revealed that only the DMA homopolymer provided effective DNA protection against DNase I degradation, while other highly condensed copolymer complexes, as judged from TEM and gel electrophoresis, only partially protected the DNA. However, AFM images indicated that the same highly condensed complexes have less condensed regions, which we believe to be the initiation sites for enzymatic attack. This indicates that the open structures observed by AFM of the DNA complexation by the DMA(x)MPC30 copolymer series are closer to in vivo morphology when compared to TEM.

Phosphorylcholine-polycation diblock copolymers as synthetic vectors for gene delivery.

A novel 2-(dimethylamino)ethyl methacrylate-block-2-(methacryloyloxyethyl phosphorylcholine) (DMAEMA-MPC) diblock copolymer was synthesized and investigated as a new non-viral vector for gene delivery. The attractive perspective of this phosphorylcholine (PC)-based material is its propensity to condense DNA efficiently via the cationic DMAEMA block, as previously demonstrated for the respective homopolymer, with the MPC block acting as a biocompatible steric stabilizer. Two series of DMAEMA-MPC diblock copolymers were synthesized for evaluation, varying independently and systematically either MPC or DMAEMA block length. Markedly different DNA-copolymer complexes were observed depending on the copolymer molecular composition. Certain polymeric structures led to formation of highly condensed, sterically stabilized DNA complexes of 120-140 nm diameter, while some resulted in partly condensed DNA-polymer complexes with 'spaghetti' structures, indicating the importance of a copolymer composition to balance condensing and steric stabilization effect. A low level of non-specific cellular association of the complexes with optimized physicochemical properties was seen, indicating the role of MPC surface layer in the interactions with biological membranes and important property in preventing promiscuous interactions with tissues in the body and potentially allowing for cellular specific delivery of the condensates following the attachment of a targeting ligand.

Time-resolved three-dimensional concentration measurements in a gas jet.

Turbulence can greatly influence reaction and heat transfer rates in fluids. The topology of the three-dimensional interface between mixing fluids directly determines the location and degree of reaction. The time-resolved measurement of the three-dimensional concentration field in a transitional gas jet is reported. A thin sheet of laser light was swept through the flow volume by a rotating mirror in a time brief enough that motion of the gas was minimal. The light sheet illuminated different parallel planes within the flow, and light scattered from particles seeding the jet was imaged onto a detector. The series of two-dimensional measurements made during one scan of the flow volume constituted a full three-dimensional mapping of structures within the flow. Computer graphics software was used to reconstruct and visualize three-dimensional surfaces of constant concentration and the magnitude of the concentration gradient vector over such surfaces.

Discrimination of normal and atherosclerotic aorta by laser-induced fluorescence.

Precise targeting of laser energy to atherosclerotic plaque is crucial for the safe performance of laser angioplasty. The present study was designed to evaluate whether laser-induced fluorescence could distinguish atherosclerotic from normal aorta. Segments of human aorta obtained at necropsy were classified grossly and histologically as normal aorta (n = 7), thin yellow fatty plaque (n = 5), and thick white atheromatous plaque (n = 9), and analyzed by laser-induced fluorescence spectroscopy using a pulsed nitrogen laser. Fluorescence spectra were recorded over a wavelength range from 385 to 725 nm. Normal specimens had maximal fluorescence intensity at 514 nm. A prominent fluorescence peak at 448 nm was present in specimens characterized as white atheromatous plaque and at 538 nm in specimens characterized as yellow fatty plaque. The ratios of fluorescence intensity at 448 nm/514 nm and at 538 nm/514 nm correctly classified all specimens according to their gross and histologic type (p less than .001). Thus, a "smart" laser angioplasty catheter system might incorporate low-power laser radiation for arterial fluorescence spectroscopy to guide delivery of high-power laser radiation for plaque ablation.

Explosive vaporization of a large transparent droplet irradiated by a high intensity laser.

Shadowgraph studies of the explosive vaporization of a transparent water droplet after irradiation by a high intensity beam show that dielectric breakdown occurs within the droplet shadow face and generates a dense plasma, which absorbs the laser pulse. The convective forces expel the vapor from the droplet shadow face. We have deduced (1) the vapor propagation velocities, (2) the recoil velocity of the remaining droplet, and (3) the deformation rate of the illuminated face. Droplets are noted to eject fingerlike material from the surface facing the single laser-vaporized droplet when the asymmetrical vapor intercepts the neighboring droplets.