Area-under-the-HbA1c-curve above the normal range and the prediction of microvascular outcomes: an analysis of data from the Diabetes Control and Complications Trial

AIMS

In the Diabetes Control and Complications Trial, mean updated HbA(1c) accounted for most of the differential risk of microvascular complications between intensive and conventional insulin therapy. We hypothesized, however, that a more precise measure of chronic hyperglycaemic exposure may be the incremental area-under-the-HbA(1c)-curve above the Diabetes Control and Complications Trial-standardized normal range for HbA(1c) (iAUC(HbA1c>norm)).

METHODS

Using the Principal Diabetes Control and Complications Trial data set, we compared the following three measures of chronic glycaemic exposure for their capacity to predict retinopathy, nephropathy and neuropathy during the Diabetes Control and Complications Trial: mean updated HbA(1c), iAUC(HbA1c>norm), and total area-under-the-HbA(1c)-curve (tAUC(HbA1c)). For each outcome, models using each of these three glycaemic measures were compared in the following three ways: hazard or odds ratio, χ(2) statistic, and Akaike information criterion.

RESULTS

The three glycaemic measures did not differ in their prediction of neuropathy. iAUC(HbA1c>norm) was modestly superior to mean updated HbA(1c) for predicting nephropathy (χ(2) P = 0.017, Akaike P = 0.032). In contrast, for predicting retinopathy, both iAUC(HbA1c>norm) (χ(2) P = 0.0005, Akaike P = 0.0005) and tAUC(HbA1c) (χ(2) P = 0.004, Akaike P = 0.004) were significantly better than mean updated HbA(1c). Varying its HbA(1c) threshold incrementally between 37 and 53 mmol/mol (5.5-7.0%), inclusive, did not improve the prediction of retinopathy by iAUC(HbA1c>threshold) beyond that of tAUC(HbA1c,) consistent with the concept of a continuous relationship between glycaemia and retinopathy, with no glycaemic threshold.

CONCLUSIONS

Both iAUC(HbA1c>norm) and tAUC(HbA1c) were superior to mean updated HbA(1c) for predicting retinopathy. Optimal assessment of chronic glycaemic exposure as a determinant of retinopathic risk may require consideration of both the degree of hyperglycaemia and its duration.

Maternal pregravid weight is the primary determinant of serum leptin and its metabolic associations in pregnancy, irrespective of gestational glucose tolerance status

CONTEXT

Several previous studies have investigated circulating levels of the adipokine leptin in relation to gestational diabetes mellitus (GDM). However, these studies have yielded markedly conflicting results, including increased, decreased, and unchanged leptin levels in women with GDM as compared with their peers.

OBJECTIVE

We sought to evaluate the metabolic determinants of serum leptin in a well-characterized cohort reflecting the full spectrum of glucose intolerance in pregnancy.

DESIGN, SETTING, AND PARTICIPANTS

Metabolic characterization, including oral glucose tolerance test (OGTT) and measurement of serum leptin, insulin, lipids, adiponectin, and C-reactive protein, was performed in 817 pregnant women. The OGTT identified 198 women with GDM, 142 with gestational impaired glucose tolerance, and 477 with normal glucose tolerance.

RESULTS

Median leptin (ng/ml) did not differ between the normal glucose tolerance (33.7), gestational impaired glucose tolerance (36.3), and GDM (36.4) groups (P = 0.085). On univariate correlation analysis, leptin was most strongly associated with prepregnancy body mass index (BMI) (r = 0.54, P < 0.0001), fasting insulin (r = 0.60, P < 0.0001), and C-reactive protein (r = 0.38, P < 0.0001) but only weakly associated with area under the glucose curve (AUC(glucose)) on the OGTT (r = 0.10, P = 0.0066). On multiple linear regression analysis, the strongest independent determinant of leptin was prepregnancy BMI (t = 11.55, P < 0.0001), whereas AUC(glucose) was not a significant predictor (t = -0.95, P = 0.34). Furthermore, although its respective associations with fasting insulin, triglycerides, and adiponectin varied across tertiles of prepregnancy BMI, leptin was not significantly associated with AUC(glucose) in any BMI tertile.

CONCLUSIONS

Pregravid BMI, rather than gestational glucose tolerance, is the primary determinant of serum leptin concentration in pregnancy.

Micro-nano-structured Fe₂O₃:Ti/ZnFe₂O₄ heterojunction films for water oxidation

Iron(III) oxide photoelectrodes show promise in water oxidation applications. In this study, micro-nano-structured hematite films are synthesized, and Ti ions are doped to improve photoelectric conversion efficiency. The photocurrent increases for enhanced electrical conductivity. Further enhanced photocurrent is achieved for Fe(2)O(3):Ti/ZnFe(2)O(4) heterojunction electrodes. Cyclic voltammograms combined with optical absorbance examinations demonstrate that the conduction and valence band edges of ZnFe(2)O(4) shift from those of Ti doped Fe(2)O(3) to the negative direction, which facilitates the efficient separation of electron-hole pairs at the Fe(2)O(3):Ti/ZnFe(2)O(4) interface. These findings demonstrate that, by doping hematite and by engineering the interface between the hematite and the electrolyte, charge separation can be effectively promoted and photocurrent density can be dramatically increased.

Interface engineering: Boosting the energy conversion efficiencies for nanostructured solar cells

Nanostructured solar cells have attracted increasing attention in recent years because their low cost and ease of preparation offer unique advantages and opportunities unavailable with conventional single-crystalline solar cells. The efficiencies of this kind of solar cell largely depend on the interfacial structure owing to the large specific interface areas and the inherent high density of interface states. In this review article, strategies of interface engineering will be introduced in detail. The up-to-date progress and understanding of interface engineering and its role in influencing the efficiency of nanostructured solar cells will be discussed. Some of the representative examples of the interface engineering method will be presented wherever necessary. Continued boosting of the energy conversion efficiency for nanostructured solar cells is anticipated in the coming years and will bring this kind of solar cell to the status of commercialization.

A new route to fabricate large-area, compact Ag metal mesh films with ordered pores

Ordered Si nanowire (SiNW) arrays can be fabricated by metal-assisted chemical etching. The metal mesh films (MMFs) are extremely important for achieving a high quality of the SiNWs. We have developed a two-step chemical deposition method to obtain compact porous Ag MMFs. By the separation of the nucleation and growth stages of the metal in the two-step deposition processes, the overgrowth of the metals to form randomly aggregated irregular metal particles can be overcome. Hexagonally arranged polystyrene (PS) latex microspheres have been employed as a template for the deposition of porous Ag MMFs. The spacing of the pores in the Ag MMFs is determined by the diameter of PS microspheres, and the pore size can also be tuned by changing Ar plasma etching time. One of the main advantages of the two-step deposition method lies in that Ag MMFs can be produced with PS microspheres that are not limited to a single layer, which dramatically simplifies the tedious processes of producing a monolayered PS template. The two-step chemical deposition method shows great potential in metal-assisted chemical etching.

Discordant effects on central obesity, hepatic insulin resistance, and alanine aminotransferase of low-dose metformin and thiazolidinedione combination therapy in patients with impaired glucose tolerance

Alanine aminotransferase (ALT) predicts incident type 2 diabetes (T2DM), possibly reflecting early fatty liver and hepatic insulin resistance. Thiazolidinediones and metformin can improve fatty liver and hepatic insulin resistance, respectively. In the Canadian Normoglycemia Outcome Evaluation trial, rosiglitazone/metformin (Rosi/Met, 4/1000 mg) reduced incident T2DM by 66% in subjects with impaired glucose tolerance. For insight on the hepatic effects of this therapy in relation to T2DM, we evaluated the temporal changes in waist, hepatic insulin sensitivity (1/Homeostasis Model Assessment of Insulin Resistance) and ALT in the Rosi/Met (n = 103) and placebo (n = 104) arms over median of 3.9 years. Waist did not differ between the arms. Hepatic insulin sensitivity improved in the Rosi/Met arm in year 1, but deteriorated thereafter as in the placebo arm. In contrast, Rosi/Met lowered ALT in year 1 and maintained this effect throughout the trial. Thus, low-dose Rosi/Met had no effect on central obesity, a transient effect on hepatic insulin sensitivity, and a sustained effect on ALT.

Endovascular stent-graft treatment for Stanford type A aortic dissection

OBJECTIVE

The aim of the study is to summarise our experience of endovascular stent grafting for Stanford type A aortic dissection.

DESIGN

Retrospective analysis at single centre.

METHODS

From January 2001 to January 2009, we treated 45 cases of Stanford type A aortic dissection with endovascular stent grafting. The entry tear was located at the ascending aorta in 10 cases (DeBakey type I), the aortic arch in 14 cases and the distal aortic arch or proximal descending aorta in 21 cases in which the ascending aorta was also involved by the dissection.

RESULTS

The surgical success rate was 97.8% (44/45) and 30-day mortality rate was 6.7% (3/45). Type I endoleaks occurred in 10 cases: one patient died intra-operatively, four were successfully treated with ballooning, four were sealed with aortic cuffs and one case caused by left subclavian artery (LSA) reflux was sealed with an occluder. Average follow-up time was 35.5 ± 5.4 months. Up to the most recent review or death, 32 patients had complete thrombosis and 10 had partial thrombosis inside the false lumen. Two deaths occurred after 30-days postoperatively.

CONCLUSION

Endovascular stent-graft treatment is a minimally invasive and effective method to treat Stanford type A aortic dissection.

Sodium fluoride-assisted modulation of anodized TiO₂ nanotube for dye-sensitized solar cells application

This work reports the use of sodium fluoride (in ethylene glycol electrolyte) as the replacement of hydrofluoric acid and ammonium fluoride to fabricate long and perpendicularly well-aligned TiO₂ nanotube (TNT) (up to 21 μm) using anodization. Anodizing duration, applied voltage and electrolyte composition influenced the geometry and surface morphologies of TNT. The growth mechanism of TNT is interpreted by analyzing the current transient profile and the total charge density generated during anodization. The system with low water content (2 wt %) yielded a membrane-like mesoporous TiO₂ film, whereas high anodizing voltage (70 V) resulted in the unstable film of TNT arrays. An optimized condition using 5 wt % water content and 60 V of anodizing voltage gave a stable array of nanotube with controllable length and pore diameter. Upon photoexcitation, TNTs synthesized under this condition exhibited a slower charge recombination rate as nanotube length increased. When made into cis-diisothiocyanato-bis(2,2̀-bipyridyl-4,4̀-dicarboxylato) ruthenium(II) bis (tetrabutyl-ammonium)(N719) dye-sensitized solar cells, good device efficiency at 3.33 % based on the optimized TNT arrays was achieved with longer electron time compared with most mesoporous TiO₂ films.

Associations and costs of parental symptoms of psychiatric distress in a multi-diagnosis group of children with special needs

BACKGROUND

Families supporting children with complex needs are significantly more distressed and economically disadvantaged than families of children without disability and delay. What is not known is the associations and costs of parental psychiatric distress within a multi-diagnosis group of special needs children.

METHODS

In this cross-sectional survey, families were identified from the Children's Treatment Network. Families were eligible if the child was aged 0-19 years, resided in Simcoe/York, and if there were multiple family needs (n = 429).

RESULTS

Some 42% of surveyed parents exhibited symptoms (mild to severe) of psychiatric distress. The presence of these symptoms was associated with reports of poorer social support, family dysfunction, greater adverse impact of the child's situation on the family, poorer child behaviour, unfavourable parenting styles and poorer child psychosocial functioning. The severity of the child's physical dysfunction was not related to parents/guardians most knowledgeable symptoms of psychiatric distress. Total parent costs were higher and children's uses of primary care services were higher in parents with symptoms of psychiatric distress.

CONCLUSION

Parent symptoms of psychiatric distress are a significant societal concern in families with complex needs children. Children's rehabilitation efforts need to incorporate parental mental health assessment and treatment into existing programmes. This could lead to decreases in direct and indirect healthcare utilisation costs.

Rational Construction of Polymeric Nonlinear Optical Materials. Properties of Chromophore-Functionalized Polystyrenes

Processable polymeric nonlinear optical materials can be synthesized by functionalizing a glassy macromolecule with chromophores having large quadratic hyperpolarizabilities, followed by poling in an electric field. In the present case, the functionalization of polystyrene with 4- (4-nitrophenylaza)(N-ethyl)(2-hydroxyethyl))aniline, 4-(4-N,N-dimethylaminostyryl) pyridine, and N-(4-nitrophenyl)-L-prolinol is described. Particularly noteworthy is the high level of chromophore units that can be incorporated into transparent films of these materials, the high second harmonic coefficients that can be achieved (as high as d33 – 11 × 10-9 esu at 1064 nm), and the long-term temporal stability of the second harmonic generation capacity.

Applications of PZT and Related Thin Films in Piezoelectric Microsensors

Ferroelectric thin films have been deposited on polycrystalline silicon micromechanical structures to form both physical microsensors and microactuator devices. These devices which include acoustic pressure sensors, infrared detectors, micropositioners, and stepper motors are based on either the piezoelectric or pyroelectric properties of sol-gel Pb(ZrxTi1-x)O3 or PbTiO3 deposited on surface-machined microelectromechanical structures. Several materials, micromachining, process integration, and performance issues are introduced in the description of these devices.

High glucose induces dysfunction and apoptosis in endothelial cells: is the effect of high glucose persistence more important than concentration?

Oxidative stress and inflammation are involved in the pathogenesis of diabetic endothelial dysfunction. Herein we reported the biological changes induced by hyperglycemia in human umbilical vein endothelial cells (HUVECs) and the potential underlying mechanisms sought to determine whether high glucose concentration or the persistence plays a key role in the development of vascular lesions. The HUVECs were exposed to various glucose concentrations (5, 15, 30, and 60 mmol/L of D-glucose supplemented), and several oxidative stress factors, such as NO, NOS, and ROS, and inflammatory signaling markers, such as TNF-α, TNFR, RIP, TRADD, TRAF-2 and NF-κB, were analyzed at various times (24, 48, 72, and 96 h). High glucose (HG) induced a transient increase of NO within 24 h and decreased afterwards, in accord with the expression of eNOS. HG also increased ROS and TNF-α production and activated the TNF-α-mediated signal transduction, decreasing cell viability and inducing apoptosis. However, 3 HG groups had similar effects on HUVECs with the increased duration of exposure, which resulted in the amplified oxidative and inflammatory damage. Taken together, these findings suggest that the HG persistence exacerbates oxidative stress and activates the inflammatory-mediated signaling pathways, inducing endothelial dysfunction and apoptosis, regardless of the concentration of HG. Our results provide the first evidence that HG persistence is more important than concentration in the progress of diabetic endothelial dysfunction.

Quasi-steady-state and steady-state models for heat and moisture transport in textile assemblies

Heat and moisture transport plays an important role in many engineering areas. In many sweat transport systems, such as clothing assembly, the moisture concentration (or sweat) is relative small and the air concentration reaches a steady state quickly. In this paper, a quasi-steady-state multi-component and multi-phase model for heat and moisture transport in porous textile materials with phase change is proposed. An analytic form of the air concentration is obtained in terms of the mixture gas (vapour and air) concentration and temperature. The new model is described in the form of a single-component flow with an extra air resistance (permeability), involving only the vapour concentration (or pressure), temperature and water content. The existence of the classical positive solutions of the corresponding steady-state model is proved. Two types of clothing assemblies are investigated numerically. The comparisons among the experimental measurements and numerical results of the fully dynamic model, the proposed quasi-steady-state model and steady-state model are also presented. Numerical results show that the proposed quasi-steady-state model is realistic and less complicated.

An investigation of the electronic properties of MgO doped with group III, IV, and V elements: trends with varying dopant atomic number

The electronic properties and the trends with varying dopant atomic number of III, IV, and V main group elements in MgO have been investigated using density functional theory. It is found that all of the geometry-optimized systems with the dopant atom replacing O in MgO exhibit half-metallic ferromagnetic properties regardless of metal or non-metal doping, and this agrees well with other theoretical computations. However, because of the high formation energy of metal atoms substituting for O atoms, we have calculated metal atom substitution for the Mg atom in MgO. We found that this system has a paramagnetic state and the formation energy is much lower than that of the former case. Finally, we have performed calculations for MgO doped with an F atom which shows a metallic behavior.