Distribution characteristics of sweat gland nerve fibres in normal humans identified by acetylcholinesterase histochemical staining.

OBJECTIVE: To quantitatively analyze distribution characteristics of sweat gland nerve fibres (SGNF) in normal Chinese individuals for obtaining a reference for early diagnosis of peripheral neuropathy. PATIENTS AND METHODS: Skin biopsy samples were collected from 192 normal Chinese individuals and divided into six, four and two groups according to anatomic sites, age and gender, respectively. SGNF morphology was observed and SGNF density (SGNFD) was determined. RESULTS: There was a significant difference in SGNFD among different anatomic sites, age and gender. A degressive tendency was observed from proximal to distal anatomic sites. SGNFD was the lowest in subjects in the 21-40-year-old age group, but was the highest in subjects in the >61-year-old age group. Overall, SGNFD fluctuated with age. SGNFD in males was significantly higher than that in females. CONCLUSIONS: Distribution characteristics of SGNF in normal individuals may serve as a reference for early diagnosis of nerve fibre damage.

Stabilized Peptide HDAC Inhibitors Derived from HDAC1 Substrate H3K56 for the Treatment of Cancer Stem-Like Cells In Vivo.

FDA-approved HDAC inhibitors exhibit dose-limiting adverse effects; thus, we sought to improve the therapeutic windows for this class of drugs. In this report, we describe a new class of peptide-based HDAC inhibitors derived from the HDAC1-specific substrate H3K56 with improved nonspecific toxicity compared with traditional small-molecular inhibitors. We showed that our designed peptides exerted superior antiproliferation effects on cancer stem-like cells with minimal toxicity to normal cells compared with the small-molecular inhibitor SAHA, which showed nonspecific toxicity to normal and cancer cells. These peptide inhibitors also inactivated cellular HDAC1 and HDAC6 and disrupted the formation of the HDAC1, LSD1, and CoREST complex. In ovarian teratocarcinoma (PA-1) and testicular embryonic carcinoma (NTERA-2) cell xenograft animal models (5 mice/group, 50 mg/kg, every other day, intraperitoneal injection), these peptides inhibited tumor growth by 80% to 90% with negligible organ (heart, liver, spleen, lung, kidney, brain) lesions. These results represent the first attempt to design chemically stabilized peptide inhibitors to investigate HDAC inhibition in cancer stem-like cells. These novel peptide inhibitors have significantly enhanced therapeutic window and offer promising opportunities for cancer therapy. SIGNIFICANCE: Selective antiproliferative effects of stabilized peptide HDAC inhibitors toward cancer stem-like cells provide a therapeutic alternative that avoids high nonspecific toxicity of current drugs.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/8/1769/F1.large.jpg.

HBx-Derived Constrained Peptides Inhibit the Secretion of Hepatitis B Virus Antigens.

Hepatitis B virus (HBV) infection is the primary cause of cirrhosis and liver cancer. Protein-protein interactions (PPIs) between HBV x protein (HBx) and its host targets, including Bcl-2, are important for cell death and viral replication. No modulators targeting these PPIs have been reported yet. Here, we developed HBx-derived constrained peptides generated by a facile macrocyclization method by joining two methionine side chains of unprotected peptides with chemoselective alkylating linkers. The resulting constrained peptides with improved cell permeability and binding affinity were effective anti-HBV modulators by blocking the secretion of viral antigens. This study clearly demonstrated HBx as a potentially important PPI target and the potential application of this efficient peptide macrocyclization strategy for targeting key PPIs.

Development of Stabilized Peptide-Based PROTACs against Estrogen Receptor α.

Peptide modulators targeting protein-protein interactions (PPIs) exhibit greater potential than small-molecule drugs in several important aspects including facile modification and relative large contact surface area. Stabilized peptides constructed by variable chemistry methods exhibit improved peptide stability and cell permeability compared to that of the linears. Herein, we designed a stabilized peptide-based proteolysis-targeting chimera (PROTAC) targeting estrogen receptor α (ERα) by tethering an N-terminal aspartic acid cross-linked stabilized peptide ERα modulator (TD-PERM) with a pentapeptide that binds the Von Hippel-Lindau (VHL) E3 ubiquitin ligase complex. The resulting heterobifunctional peptide (TD-PROTAC) selectively recruits ERα to the VHL E3 ligase complex, leading to the degradation of ERα in a proteasome-dependent manner. Compared with the control peptides, TD-PROTAC shows significantly enhanced activities in reducing the transcription of the ERα-downstream genes and inhibiting the proliferation of ERα-positive breast cancer cells. In addition, in vivo experiments indicate that TD-PROTAC leads to tumor regression in the MCF-7 mouse xenograft model. This work is a successful attempt to construct PROTACs based on cell-permeable stabilized peptides, which significantly broadens the chemical space of PROTACs and stabilized peptides.

Evaluation of biochar powder on oxygen supply efficiency and global warming potential during mainstream large-scale aerobic composting.

This study investigated the effects of biochar powder on oxygen supply efficiency and global warming potential (GWP) in the large-scale aerobic composting pattern which includes cyclical forced-turning with aeration at the bottom of composting tanks in China. A 55-day large-scale aerobic composting experiment was conducted in two different groups without and with 10% biochar powder addition (by weight). The results show that biochar powder improves the holding ability of oxygen, and the duration time (O2>5%) is around 80%. The composting process with above pattern significantly reduce CH4 and N2O emissions compared to the static or turning-only styles. Considering the average GWP of the BC group was 19.82% lower than that of the CK group, it suggests that rational addition of biochar powder has the potential to reduce the energy consumption of turning, improve effectiveness of the oxygen supply, and reduce comprehensive greenhouse effects.

An in-tether chiral center modulates the proapoptotic activity of the KLA peptide.

The helical peptide KLA (KLAKLAKKLAKLAK) is a well-known inducer of cellular apoptosis, acting to disrupt the mitochondrial membrane. However, its weak cellular uptake impedes development of any further applications. Here, we have utilized a novel in-tether chiral center induced helicity strategy (CIH) to develop a potent apoptosis inducer based on this KLA sequence. Notably, for the two resulting epimers of the CIH-KLA peptide, the CIH-KLA-(R) epimer exhibited superior cellular uptakes and special mitochondrial targeting when compared with its S counterpart. This work provides a promising and versatile method to modify the KLA peptide and a proof-of-concept application for the CIH strategy in modifying bioactive peptides.

A precisely positioned chiral center in an i, i + 7 tether modulates the helicity of the backbone peptide.

In some cases, helical peptides stabilized by an i, i + 7 tether exhibit better target binding and cellular functions compared to their i, i + 4 analogues. Herein, we carried out a systematic study of the effects of an in-tether chiral center on the i, i + 7 system. We screened the optimal cross linking mode, tether length, in-tether chiral center positions, and absolute configurations. From these studies, we determined that a chiral center of R absolute configuration at the γ-position to the C-terminal of a 10-membered tether could function to efficiently induce helicity of the backbone peptides. This is an important addition to the current i, i + 4 in-tether chiral center induced helicity strategy (CIH strategy), and could have broad biological applications.

Quantitative characterization of enzyme adsorption and hydrolytic performance for ultrafine grinding pretreated corn stover.

Quantitative analysis of enzyme adsorption and hydrolysis were performed for sieve-based grinding corn stover (SGCS) and ultrafine grinding corn stover (UGCS)1 with different enzyme consumptions. The UGCS presented significantly higher enzyme adsorption quantity (5.15mg/g for UGCS, 1.33mg/g for SGCS), higher glucose yield (49.75% for UGCS, 28.75% for SGCS) under 20FPU/g and higher binding enzyme proportion (41.32% for UGCS, 10.64% for SGCS under 5FPU/g) which can be attributed to the more accessible microstructure properties. The relationship between enzyme adsorption and hydrolytic production was directly proportional for SGCS (GY1=21.04×AQ1+1.86 (R2=0.95)) while was exponential for UGCS (GY2=49.42×(1-e-0.57×AQ2) (R2=0.99)),2 indicating that overmuch enzyme consumption was not advisable for UGCS at economical aspect.

A novel film-pore-surface diffusion model to explain the enhanced enzyme adsorption of corn stover pretreated by ultrafine grinding.

BACKGROUND: Ultrafine grinding is an environmentally friendly pretreatment that can alter the degree of polymerization, the porosity and the specific surface area of lignocellulosic biomass and can, thus, enhance cellulose hydrolysis. Enzyme adsorption onto the substrate is a prerequisite for the enzymatic hydrolysis process. Therefore, it is necessary to investigate the enzyme adsorption properties of corn stover pretreated by ultrafine grinding. RESULTS: The ultrafine grinding pretreatment was executed on corn stover. The results showed that ultrafine grinding pretreatment can significantly decrease particle size [from 218.50 µm of sieve-based grinding corn stover (SGCS) to 17.45 µm of ultrafine grinding corn stover (UGCS)] and increase the specific surface area (SSA), pore volume (PV) and surface composition (SSA: from 1.71 m(2)/g of SGCS to 2.63 m(2)/g of UGCS, PV: from 0.009 cm(3)/g of SGCS to 0.024 m(3)/g of UGCS, cellulose surface area: from 168.69 m(2)/g of SGCS to 290.76 m(2)/g of UGCS, lignin surface area: from 91.46 m(2)/g of SGCS to 106.70 m(2)/g of UGCS). The structure and surface composition changes induced by ultrafine grinding increase the enzyme adsorption capacity from 2.83 mg/g substrate of SGCS to 5.61 mg/g substrate of UGCS. A film-pore-surface diffusion model was developed to simultaneously predict the enzyme adsorption kinetics of both the SGCS and UGCS. Satisfactory predictions could be made with the model based on high R (2) and low RMSE values (R (2) = 0.95 and RMSE = 0.16 mg/g for the UGCS, R (2) = 0.93 and RMSE = 0.09 mg/g for the SGCS). The model was further employed to analyze the rate-limiting steps in the enzyme adsorption process. Although both the external-film and internal-pore mass transfer are important for enzyme adsorption on the SGCS and UGCS, the UGCS has a lower internal-pore resistance compared to the SGCS. CONCLUSIONS: Ultrafine grinding pretreatment can enhance the enzyme adsorption onto corn stover by altering structure and surface composition. The film-pore-surface diffusion model successfully captures features on enzyme adsorption on ultrafine grinding pretreated corn stover. These findings identify wherein the probable rate-limiting factors for the enzyme adsorption reside and could, therefore, provide a basis for enhanced cellulose hydrolysis processes.

Integrated chemical and multi-scale structural analyses for the processes of acid pretreatment and enzymatic hydrolysis of corn stover.

Corn stover was pretreated with acid under moderate conditions (1.5%, w/w, 121°C, 60min), and kinetic enzymolysis experiments were performed on the pretreated substrate using a mixture of Celluclast 1.5L (20FPU/g dry substrate) and Novozyme 188 (40CBU/g dry substrate). Integrated chemical and multi-scale structural methods were then used to characterize both processes. Chemical analysis showed that acid pretreatment removed considerable hemicellulose (from 19.7% in native substrate to 9.28% in acid-pretreated substrate) and achieved a reasonably high conversion efficiency (58.63% of glucose yield) in the subsequent enzymatic hydrolysis. Multi-scale structural analysis indicated that acid pretreatment caused structural changes via cleaving acetyl linkages, solubilizing hemicellulose, relocating cell wall surfaces and enlarging substrate porosity (pore volume increased from 0.0067cm(3)/g in native substrate to 0.019cm(3)/g in acid-pretreated substrate), thereby improving the polysaccharide digestibility.

A multi-scale biomechanical model based on the physiological structure and lignocellulose components of wheat straw.

Biomechanical behavior is a fundamental property for the efficient utilization of wheat straw in such applications as fuel and renewable materials. Tensile experiments and lignocellulose analyses were performed on three types of wheat straw. A multi-scale finite element model composed of the microscopic model of the microfibril equivalent volume element and the macroscopic model of straw tissue was proposed based on the physiological structure and lignocellulose components of wheat straw. The tensile properties of wheat straw were simulated by ANSYS software. The predicted stress-strain data were compared with the observed data, and good correspondence was achieved for all three types of wheat straw. The validated multi-scale finite-element (FE) model was then used to investigate the effect of the lignocellulose components on the biomechanical properties of wheat straw. More than 80% of stress is carried by the cellulose fiber, whereas the strain is mainly carried by the amorphous cellulose.

In silico prediction of percutaneous absorption and disposition kinetics of chemicals.

PURPOSE: To develop in-silico model for predicting percutaneous absorption and disposition kinetics of chemicals in skin layers so as to facilitate the design of transdermal drug delivery systems and skin care products, and risk assessment of occupational or consumer exposure. METHODS: A general-purpose computer model for simulating skin permeation, absorption and disposition kinetics in the stratum corneum, viable dermis and dermis has been developed. Equations have been proposed for determining the partition and diffusion properties of chemicals by considering molecular partition, binding and mobility in skin layers. In vitro skin penetration data of 12 chemicals was used to validate the model. RESULTS: The observed and simulated permeation and disposition in skin layers were compared for 12 tested chemicals. For most tested chemicals, the experimental and model results are in good agreement with the coefficient of determination >0.80 and relative root mean squared error <1.20. The disposition kinetic parameters of the maximum concentration and the area under the curve in the viable epidermis and dermis initially increased with hydrophobicity, but reached maxima and then decreased with further increase of hydrophobicity. CONCLUSIONS: By considering skin physiological structure and composition, the partition and diffusion properties of chemicals in skin layers are determined. This allows in-silico simulation of percutaneous permeation, absorption and disposition kinetics of wide chemical space. The model produced results in good agreement with experimental data of 12 chemicals, suggesting a much improved framework to support transdermal delivery of drug and cosmetic actives as well as integrated risk assessment.

A novel diffusion-biphasic hydrolysis coupled kinetic model for dilute sulfuric acid pretreatment of corn stover.

Kinetic experiments on the dilute sulfuric acid pretreatment of corn stover were performed. A high xylan removal and a low inhibitor concentration were achieved by acid pretreatment. A novel diffusion-hydrolysis coupled kinetic model was proposed. The contribution to the xylose yield was analyzed by the kinetic model. Compared with the inhibitor furfural negatively affecting xylose yield, the fast and slow-hydrolyzing xylan significantly contributed to the xylose yield, however, their dominant roles were dependent on reaction temperature and time. The impact of particle size and acid concentration on the xylose yield were also investigated. The diffusion process may significantly influence the hydrolysis of large particles. Increasing the acid concentration from 0.15 M to 0.30 M significantly improved the xylose yield, whereas the extent of improvement decreased to near-quantitative when further increasing acid loading. These findings shed some light on the mechanism for dilute sulfuric acid hydrolysis of corn stover.

Discovery and SAR study of piperidine-based derivatives as novel influenza virus inhibitors.

A series of piperidine-based derivatives were identified as novel and potent inhibitors of the influenza virus through structural modification of a compound that was selected from a high-throughput screen. Various analogues were synthesized and confirmed as inhibitors. The structure­activity relationship (SAR) studies suggested that the ether linkage between the quinoline and piperidine is critical for the inhibitory activity. The optimized compound tert-butyl 4-(quinolin-4-yloxy)piperidine-1-carboxylate 11e had an excellent inhibitory activity against influenza virus infection from a variety of influenza virus strains, with EC50 values as low as 0.05 µM. The selectivity index value (SI = MLD50/EC50) of 11e is over 160000 based on cytotoxicity, measured by MTT assays of three cell lines. We carried out a time-of-addition experiment to delineate the mechanism of inhibition. The result indicates that 11e interferes with the early to middle stage of influenza virus replication.

Two-dimensional correlation spectroscopy (2D-COS) variable selection for near-infrared microscopy discrimination of meat and bone meal in compound feed.

This article presents a novel method for combining auto-peak and cross-peak information for sensitive variable selection in synchronous two-dimensional correlation spectroscopy (2D-COS). This variable selection method is then applied to the case of near-infrared (NIR) microscopy discrimination of meat and bone meal (MBM). This is of important practical value because MBM is currently banned in ruminate animal compound feed. For the 2D-COS analysis, a set of NIR spectroscopy data of compound feed samples (adulterated with varying concentrations of MBM) was pretreated using standard normal variate and detrending (SNVD) and then mapped to the 2D-COS synchronous matrix. For the auto-peak analysis, 12 main sensitive variables were identified at 6852, 6388, 6320, 5788, 5600, 5244, 4900, 4768, 4572, 4336, 4256, and 4192 cm(-1). All these variables were assigned their specific spectral structure and chemical component. For the cross-peak analysis, these variables were divided into two groups, each group containing the six sensitive variables. This grouping resulted in a correlation between the spectral variables that was in accordance with the chemical-component content of the MBM and compound feed. These sensitive variables were then used to build a NIR microscopy discrimination model, which yielded a 97% correct classification. Moreover, this method detected the presence of MBM when its concentration was less than 1% in an adulterated compound feed sample. The concentration-dependent 2D-COS-based variable selection method developed in this study has the unique advantages of (1) introducing an interpretive aspect into variable selection, (2) substantially reducing the complexity of the computations, (3) enabling the transferability of the results to discriminant analysis, and (4) enabling the efficient compression of spectral data.

A study on Fe(2+) - α-helical-rich keratin complex formation using isothermal titration calorimetry and molecular dynamics simulation.

Iron binding to protein is common in biological processes of dioxygen transport, electron transfer as well as in stabilizing drug-protein complexes. α-Helix is the most prevalent secondary structure of proteins. In this study, Fe(2+) binding to α-helix has been studied by isothermal titration calorimetry (ITC) and explicitly solvated molecular dynamics (MD) simulation. Ferrous gluconate and α-helix-rich keratin are used for the ITC study and the results revealed followed one set of identical sites binding model. The MD simulations further revealed that only the acidic side-chain functional groups and η(2) (O,O) coordination modes are involved in the binding of Fe(2+) to α-helix. The ITC results also showed that the binding of ferrous gluconate to keratin was entropy driven and the higher the temperature, the stronger the binding free energy. The favorable entropy of Fe(2+) binding to keratin was attributed to the displacement of water molecules on the α-helix surface, and was confirmed via MD simulations. The most stable coordination states of Fe(2+) and α-helix were identified via simulation: Fe(2+) stacks between two glutamic acid side chain carboxylate groups, displacing water molecules. The binding free energies calculated using MD simulation and the theoretical values were in excellent agreement with the ITC results.

Visual recognition of fishmeal and meat and bone meal using temperature-dependent two-dimensional correlation near-infrared spectroscopy.

The purpose of this study is to investigate the efficiency of two-dimensional correlation spectroscopy (2D-COS) in recognizing the authenticity and purity of fishmeal (FM) and meat and bone meal (MBM), which are both complex mixtures with high similarity. Twenty FM samples and 20 MBM samples were obtained and examined. Temperature-dependent near-infrared (NIR) spectra were obtained using a Spectrum 400 spectrometer from 20 °C to 60 °C with an interval of 10 °C. Wavelet transform (Daubechies 5 wavelet with five levels) and baseline correction were applied to the temperature-dependent spectra in the wave range of 6000-5400 cm(-1). A 2D-COS synchronous map was calculated and scaled to the range between -1 and 1. A correlation coefficient was employed to quantitatively evaluate the visual differences of synchronous maps. The results show minor differences in NIR spectral absorbency of FM and MBM, and such differences are caused by appropriate temperature perturbation and enlarged by the 2D-COS method. The sensitive wave range is found in the area of 5800-5400 cm(-1). FM and MBM have observable pattern differences in the synchronous maps. Further quantitative evaluation of synchronous maps confirms correct recognizing results. Temperature-dependent 2D-COS is capable of recognizing the authenticity and purity of highly similar FM and MBM samples.

Review of the application of near-infrared spectroscopy technology to determine the chemical composition of animal manure.

Animal manure contains a variety of chemical constituents that are highly valuable to agriculture, including nitrogen, phosphorus, potassium, and metal micronutrients. Although appropriately applied manure has numerous positive attributes, the excessive application of manure may lead to pollution of the atmosphere, water, or soil. To reconcile precision agriculture and the potential negative environmental influences of animal manure, it is necessary to develop rapid and robust methods to evaluate the chemical composition of animal manure. This paper summarizes recent advances in near-infrared reflectance spectroscopy (NIRS) in predicting moisture, dry matter, organic matter, nitrogen, phosphorus, carbon, and metal content in animal manure. The results indicate the high potential of NIRS as an efficient tool for monitoring the chemical composition of animal manure. Future prospects and needs related to increasing the feasibility of the industrial application of NIRS and improving NIRS prediction precision in determining the chemical composition of animal manure are discussed.

Recent advances in predicting skin permeability of hydrophilic solutes.

Understanding the permeation of hydrophilic molecules is of relevance to many applications including transdermal drug delivery, skin care as well as risk assessment of occupational, environmental, or consumer exposure. This paper reviews recent advances in modeling skin permeability of hydrophilic solutes, including quantitative structure-permeability relationships (QSPR) and mechanistic models. A dataset of measured human skin permeability of hydrophilic and low hydrophobic solutes has been compiled. Generally statistically derived QSPR models under-estimate skin permeability of hydrophilic solutes. On the other hand, including additional aqueous pathway is necessary for mechanistic models to improve the prediction of skin permeability of hydrophilic solutes, especially for highly hydrophilic solutes. A consensus yet has to be reached as to how the aqueous pathway should be modeled. Nevertheless it is shown that the contribution of aqueous pathway can constitute to more than 95% of the overall skin permeability. Finally, future prospects and needs in improving the prediction of skin permeability of hydrophilic solutes are discussed.

Kinetics and equilibrium of solute diffusion into human hair.

The uptake kinetics of five molecules by hair has been measured and the effects of pH and physical chemical properties of molecules were investigated. A theoretical model is proposed to analyze the experimental data. The results indicate that the binding affinity of solute to hair, as characterized by hair-water partition coefficient, scales to the hydrophobicity of the solute and decreases dramatically as the pH increases to the dissociation constant. The effective diffusion coefficient of solute depended not only on the molecular size as most previous studies suggested, but also on the binding affinity as well as solute dissociation. It appears that the uptake of molecules by hair is due to both hydrophobic interaction and ionic charge interaction. Based on theoretical considerations of the cellular structure, composition and physical chemical properties of hair, quantitative-structure-property-relationships (QSPR) have been proposed to predict the hair-water partition coefficient (PC) and the effective diffusion coefficient (D (e)) of solute. The proposed QSPR models fit well with the experimental data. This paper could be taken as a reference for investigating the adsorption properties for polymeric materials, fibres, and biomaterials.