Flexible layer-structured Bi2Te3 thermoelectric on a carbon nanotube scaffold

Inorganic chalcogenides are traditional high-performance thermoelectric materials. However, they suffer from intrinsic brittleness and it is very difficult to obtain materials with both high thermoelectric ability and good flexibility. Here, we report a flexible thermoelectric material comprising highly ordered Bi₂Te₃ nanocrystals anchored on a single-walled carbon nanotube (SWCNT) network, where a crystallographic relationship exists between the Bi₂Te₃ <[Formula: see text]> orientation and SWCNT bundle axis. This material has a power factor of ~1,600 μW m^-1 K^-2 at room temperature, decreasing to 1,100 μW m^-1 K^-2 at 473 K. With a low in-plane lattice thermal conductivity of 0.26 ± 0.03 W m^-1 K^-1, a maximum thermoelectric figure of merit (ZT) of 0.89 at room temperature is achieved, originating from a strong phonon scattering effect. The origin of the excellent flexibility and thermoelectric performance of the Bi₂Te₃-SWCNT material is attributed, by experimental and computational evidence, to its crystal orientation, interface and nanopore structure. Our results provide insight into the design and fabrication of high-performance flexible thermoelectric materials.

Continuous Fabrication of Meter-Scale Single-Wall Carbon Nanotube Films and their Use in Flexible and Transparent Integrated Circuits

Single-wall carbon nanotubes (SWCNTs), especially in the form of large-area and high-quality thin films, are a promising material for use in flexible and transparent electronics. Here, a continuous synthesis, deposition, and transfer technique is reported for the fabrication of meter-scale SWCNT thin films, which have an excellent optoelectrical performance including a low sheet resistance of 65 Ω/◽ with a transmittance of 90% at a wavelength of 550 nm. Using these SWCNT thin films, high-performance all-CNT thin-film transistors and integrated circuits are demonstrated, including 101-stage ring oscillators. The results pave the way for the future development of large-scale, flexible, and transparent electronics based on CNT thin films.

Ultrahigh-performance transparent conductive films of carbon-welded isolated single-wall carbon nanotubes

Single-wall carbon nanotubes (SWCNTs) are ideal for fabricating transparent conductive films because of their small diameter, good optical and electrical properties, and excellent flexibility. However, a high intertube Schottky junction resistance, together with the existence of aggregated bundles of SWCNTs, leads to a degraded optoelectronic performance of the films. We report a network of isolated SWCNTs prepared by an injection floating catalyst chemical vapor deposition method, in which crossed SWCNTs are welded together by graphitic carbon. Pristine SWCNT films show a record low sheet resistance of 41 ohm □^-1 at 90% transmittance for 550-nm light. After HNO₃ treatment, the sheet resistance further decreases to 25 ohm □^-1. Organic light-emitting diodes using this SWCNT film as anodes demonstrate a low turn-on voltage of 2.5 V, a high current efficiency of 75 cd A^-1, and excellent flexibility. Investigation of isolated SWCNT-based field-effect transistors shows that the carbon-welded joints convert the Schottky contacts between metallic and semiconducting SWCNTs into near-ohmic ones, which significantly improves the conductivity of the transparent SWCNT network. Our work provides a new avenue of assembling individual SWCNTs into macroscopic thin films, which demonstrate great potential for use as transparent electrodes in various flexible electronics.

[Comparison of Bacteria ERIC-PCR Fingerprints of Index Fingers and Contactants]

OBJECTIVES

To explore the bacteria relevance between index fingers and contactant' surfaces （mobile phone touch screen and desktop of personal office table）.

METHODS

Bacteria were collected from the index fingers, mobile phone touch screen and desktop of personal office table of 10 volunteers. Enterobacterial repetitive intergenic consensus （ERIC）-PCR fingerprint was established by PCR amplification technique of metagenome.

RESULTS

There were 7 volunteers' ERIC-PCR fingerprints of index fingers matched that took from the mobile phone touch screens, and different from each other. There were 3 volunteers' ERIC-PCR fingerprints of index fingers matched that took from desk top of personal office table, and other 7 volunteers' ERIC-PCR fingerprints did not match perfectly with that took from desk top of personal office table, but had at least one similar band for both.

CONCLUSIONS

The bacteria on index finger shows individual specificity, which on mobile phone touching screen and personal desktop may be a new biological sample of forensic identification.

Ultrafast Growth of High-Quality Monolayer WSe2 on Au

The ultrafast growth of high-quality uniform monolayer WSe₂ is reported with a growth rate of ≈26 µm s^-1 by chemical vapor deposition on reusable Au substrate, which is ≈2-3 orders of magnitude faster than those of most 2D transition metal dichalcogenides grown on nonmetal substrates. Such ultrafast growth allows for the fabrication of millimeter-size single-crystal WSe₂ domains in ≈30 s and large-area continuous films in ≈60 s. Importantly, the ultrafast grown WSe₂ shows excellent crystal quality and extraordinary electrical performance comparable to those of the mechanically exfoliated samples, with a high mobility up to ≈143 cm² V^-1 s^-1 and ON/OFF ratio up to 9 × 10⁶ at room temperature. Density functional theory calculations reveal that the ultrafast growth of WSe₂ is due to the small energy barriers and exothermic characteristic for the diffusion and attachment of W and Se on the edges of WSe₂ on Au substrate.

Circular Graphene Platelets with Grain Size and Orientation Gradients Grown by Chemical Vapor Deposition

Monolayer circular graphene platelets with a grain structure gradient in the radial direction are synthesized by chemical vapor deposition on immiscible W-Cu substrates. Because of the different interactions and growth behaviors of graphene on Cu and tungsten carbide, such substrates cause the formation of grain size and orientation gradients through the competition between Cu and tungsten carbide in graphene growth.

Serum total bilirubin levels are negatively correlated with metabolic syndrome in aged Chinese women: a community-based study

We evaluated serum total bilirubin levels as a predictor for metabolic syndrome (MetS) and investigated the relationship between serum total bilirubin levels and MetS prevalence. This cross-sectional study included 1728 participants over 65 years of age from Eastern China. Anthropometric data, lifestyle information, and previous medical history were collected. We then measured serum levels of fasting blood-glucose, total cholesterol, triglycerides, and total bilirubin, as well as alanine aminotransferase activity. The prevalence of MetS and each of its individual component were calculated per quartile of total bilirubin level. Logistic regression was used to assess the correlation between serum total bilirubin levels and MetS. Total bilirubin level in the women who did not have MetS was significantly higher than in those who had MetS (P<0.001). Serum total bilirubin quartiles were linearly and negatively correlated with MetS prevalence and hypertriglyceridemia (HTG) in females (P<0.005). Logistic regression showed that serum total bilirubin was an independent predictor of MetS for females (OR: 0.910, 95%CI: 0.863-0.960; P=0.001). The present study suggests that physiological levels of serum total bilirubin might be an independent risk factor for aged Chinese women, and the prevalence of MetS and HTG are negatively correlated to serum total bilirubin levels.

Oral Mucosa Harbors a High Frequency of Endothelial Cells: A Novel Postnatal Cell Source for Angiogenic Regeneration

Endothelial progenitor cells/endothelial cells (EPCs/ECs) have great potential to treat pathological conditions such as cardiac infarction, muscle ischemia, and bone fractures, but isolation of EPC/ECs from existing cell sources is challenging due to their low EC frequency. We have isolated endothelial progenitor (EP)-like cells from rat oral mucosa and characterized their yield, immunophenotype, growth, and in vivo angiogenic potential. The frequency of EP-like cells derived from oral mucosa is thousands of folds higher than EPCs derived from donor-match bone marrow samples. EP-like cells from oral mucosa were positive for EC markers CD31, VE-Cadherin, and VEGFR2. Oral mucosa-derived EP-like cells displayed robust uptake of acetylated low-density lipoprotein and formed stable capillary networks in Matrigel. Subcutaneously implanted oral mucosa-derived EP-like cells anastomosed with host blood vessels, implicating their ability to elicit angiogenesis. Similar to endothelial colony-forming cells, EP-like cells from oral mucosa have a significantly higher proliferative rate than human umbilical vein endothelial cells. These findings identify a putative EPC source that is easily accessible in the oral cavity, potentially from discarded tissue specimens, and yet with robust yield and potency for angiogenesis in tissue and organ regeneration.

Poor sleep in middle-aged women is not associated with menopause per se

Whether sleep problems of menopausal women are associated with vasomotor symptoms and/or changes in estrogen levels associated with menopause or age-related changes in sleep architecture is unclear. This study aimed to determine if poor sleep in middle-aged women is correlated with menopause. This study recruited women seeking care for the first time at the menopause outpatient department of our hospital. Inclusion criteria were an age ≥40 years, not taking any medications for menopausal symptoms, and no sleeping problems or depression. Patients were assessed with the Pittsburgh Sleep Quality Index (PSQI), modified Kupperman Index (KI), and Menopause Rating Scale (MRS). A PSQI score of <7 indicated no sleep disorder and ≥7 indicated a sleep disorder. Blood specimens were analyzed for follicle-stimulating hormone and estradiol levels. A total of 244 women were included in the study; 103 (42.2%) were identified as having a sleep disorder and 141 as not having one. In addition, 156 (64%) women were postmenopausal and 88 (36%) were not menopausal. Follicle-stimulating hormone and estradiol levels were similar between the groups. Patients with a sleep disorder had a significantly higher total modified KI score and total MRS score (both, P<0.001) compared with those without a sleep disorder. Correlations of the PSQI total score with the KI and MRS were similar in menopausal and non-menopausal women. These results do not support that menopause per se specifically contributes to sleep problems.

[The imaging analysis of the age-related changes on maxillary sinus]

Objective:The aim of this study is to investigate the age-related changes rules of maxillary sinus.Method:The 540 patients (1 080 sides) with normal data of deputy sinus in spiral CT were enrolled,including 270 cases of male and female,age from 7 to 81 years old.They are divided into 9 groups according to the age:Group A at the age of 7-12 years old,Group B at the age of 13-17,Group C at the age of 18-20 years old,Group D at the age of 21-24 years old,Group E at the age of 25-28 years,Group F at the age of 29-35 years old,Group G at the age of 36-40 years old,Group H at the age of 41-65 years old,and Group I is more than 65 years old.By the gender,the patients in each group was divided into male and female groups.There are 30 cases in each group(60 sides).The volumes and the three-dimensional diameters of the maxillary sinus were measured,and the coefficient of gasification of them were calculated.Result:The maxillary sinus volume and 3 D lines have almost the same change trend along with the age between the male and female group;From 7 to 20 ages,they are increased linearly,13 to 17 fastest-growing;18 to 20 years old reached to peak;declined slightly in 21-28 years old,29-35 a second growth peak,and 36 to 40 years old have fallen sharply,to reaching a steady state after 41 years old;The gasification coefficient has no difference among all groups.Conclusion:The volume changes with the age-related on maxillary sinus is in the adolescent stage.It reaches a steady state in the middle and old age stage,and gasification coefficient on maxillary sinus has no age-related changes among all groups.

Growth of semiconducting single-wall carbon nanotubes with a narrow band-gap distribution

The growth of high-quality semiconducting single-wall carbon nanotubes with a narrow band-gap distribution is crucial for the fabrication of high-performance electronic devices. However, the single-wall carbon nanotubes grown from traditional metal catalysts usually have diversified structures and properties. Here we design and prepare an acorn-like, partially carbon-coated cobalt nanoparticle catalyst with a uniform size and structure by the thermal reduction of a [Co(CN)6](3-) precursor adsorbed on a self-assembled block copolymer nanodomain. The inner cobalt nanoparticle functions as active catalytic phase for carbon nanotube growth, whereas the outer carbon layer prevents the aggregation of cobalt nanoparticles and ensures a perpendicular growth mode. The grown single-wall carbon nanotubes have a very narrow diameter distribution centred at 1.7 nm and a high semiconducting content of >95%. These semiconducting single-wall carbon nanotubes have a very small band-gap difference of ∼0.08 eV and show excellent thin-film transistor performance.

Mesenchymal dental pulp cells attenuate dentin resorption in homeostasis

Dentin in permanent teeth rarely undergoes resorption in development, homeostasis, or aging, in contrast to bone that undergoes periodic resorption/remodeling. The authors hypothesized that cells in the mesenchymal compartment of dental pulp attenuate osteoclastogenesis. Mononucleated and adherent cells from donor-matched rat dental pulp (dental pulp cells [DPCs]) and alveolar bone (alveolar bone cells [ABCs]) were isolated and separately cocultured with primary rat splenocytes. Primary splenocytes readily aggregated and formed osteoclast-like cells in chemically defined osteoclastogenesis medium with 20 ng/mL of macrophage colony-stimulating factor (M-CSF) and 50 ng/mL of receptor activator of nuclear factor κB ligand (RANKL). Strikingly, DPCs attenuated osteoclastogenesis when cocultured with primary splenocytes, whereas ABCs slightly but significantly promoted osteoclastogenesis. DPCs yielded ~20-fold lower RANKL expression but >2-fold higher osteoprotegerin (OPG) expression than donor-matched ABCs, yielding a RANKL/OPG ratio of 41:1 (ABCs:DPCs). Vitamin D3 significantly promoted RANKL expression in ABCs and OPG in DPCs. In vivo, rat maxillary incisors were atraumatically extracted (without any tooth fractures), followed by retrograde pulpectomy to remove DPCs and immediate replantation into the extraction sockets to allow repopulation of the surgically treated root canal with periodontal and alveolar bone-derived cells. After 8 wk, multiple dentin/root resorption lacunae were present in root dentin with robust RANKL and OPG expression. There were areas of dentin resoprtion alternating with areas of osteodentin formation in root dentin surface in the observed 8 wk. These findings suggest that DPCs of the mesenchymal compartment have an innate ability to attenuate osteoclastogenesis and that this innate ability may be responsible for the absence of dentin resorption in homeostasis. Mesenchymal attenuation of dentin resorption may have implications in internal resorption in the root canal, pulp/dentin regeneration, and root resorption in orthodontic tooth movement.

High-quality, highly concentrated semiconducting single-wall carbon nanotubes for use in field effect transistors and biosensors

We developed a simple and scalable selective synthesis method of high-quality, highly concentrated semiconducting single-wall carbon nanotubes (s-SWCNTs) by in situ hydrogen etching. Samples containing ~93% s-SWCNTs were obtained in bulk. These s-SWCNTs with good structural integrity showed a high oxidation resistance temperature of ~800 °C. Thin-film transistors based on the s-SWCNTs demonstrated a high carrier mobility of 21.1 cm(2) V(-1) s(-1) at an on/off ratio of 1.1 × 10(4) and a high on/off ratio of 4.0 × 10(5) with a carrier mobility of 7.0 cm(2) V(-1) s(-1). A biosensor fabricated using the s-SWCNTs had a very low dopamine detection limit of 10(-18) mol/L at room temperature.

A review of carbon nanotube- and graphene-based flexible thin-film transistors

Carbon nanotubes (CNTs) and graphene have attracted great attention for numerous applications for future flexible electronics, owing to their supreme properties including exceptionally high electronic conductivity and mechanical strength. Here, the progress of CNT- and graphene-based flexible thin-film transistors from material preparation, device fabrication techniques to transistor performance control is reviewed. State-of-the-art fabrication techniques of thin-film transistors are divided into three categories: solid-phase, liquid-phase, and gas-phase techniques, and possible scale-up approaches to achieve realistic production of flexible nanocarbon-based transistors are discussed. In particular, the recent progress in flexible all-carbon nanomaterial transistor research is highlighted, and this all-carbon strategy opens up a perspective to realize extremely flexible, stretchable, and transparent electronics with a relatively low-cost and fast fabrication technique, compared to traditional rigid silicon, metal and metal oxide electronics.

[Changes in serum insulin-like growth factor-1 and insulin-like growth factor-binding protein-3, and their significance in children with left-to-right shunt congenital heart disease associated with heart failure]

OBJECTIVE

To investigate changes in serum insulin-like growth factor-1 (IGF-1) and insulin-like growth factor-binding protein-3 (IGFBP-3) and their significance in children with left-to-right shunt congenital heart disease (CHD) associated with heart failure (HF).

METHODS

Twenty healthy children (control group), 20 children with HF, without basic heart disease (HF group), 20 children with left-to-right shunt CHD, without HF (CHD group), and 30 children with left-to-right shunt CHD associated with HF (CHD+HF group) were included in the study. These groups were compared in terms of serum IGF-1 and IGFBP-3 levels. According to the New York Heart Association (NYHA) Functional Classification, the CHD+HF group was further divided into NYHA-II, NYHA-III and NYHA-IV subgroups and the subgroups were compared in terms of serum IGF-1, IGFBP-3, and cardiac troponin I (cTnI) levels. The correlation of serum IGF-1 and IGFBP-3 levels with serum cTnI level in the CHD+HF group was analyzed.

RESULTS

The CHD group showed decreased serum IGF-1 and IGFBP-3 levels compared with the control group (P<0.01). The CHD+HF group showed a significantly decreased serum IGF-1 level compared with the control group (P<0.01) and CHD group (P<0.05). The HF group had significantly increased serum IGF-1 and IGFBP-3 levels compared with other groups (P<0.01). The NYHA-II subgroup had the highest serum IGF-1 level and the NYHA-IV subgroup had the lowest serum IGF-1 level (P<0.01). In the CHD+HF group, serum IGF-1 and IGFBP-3 levels were negatively correlated with serum cTnI level (r=-0.692, P<0.05; r=-0.530, P<0.05).

CONCLUSIONS

Serum IGF-1 level can be used as an objective condition evaluation indicator for CHD, and low serum IGF-1 level is a risk factor for HF. This also provides a clinical basis for treatment of HF using exogenous IGF-1.

Enrichment of semiconducting single-walled carbon nanotubes by carbothermic reaction for use in all-nanotube field effect transistors

Selective removal of metallic single-walled carbon nanotubes (SWCNTs) and consequent enrichment of semiconducting SWCNTs were achieved through an efficient carbothermic reaction with a NiO thin film at a relatively low temperature of 350 °C. All-SWCNT field effect transistors (FETs) were fabricated with the aid of a patterned NiO mask, in which the as-grown SWCNTs behaving as source/drain electrodes and the remaining semiconducting SWCNTs that survive in the carbothermic reaction as a channel material. The all-SWCNT FETs demonstrate improved current ON/OFF ratios of ∼10(3).

Analysis of cipadesin limonoids from Cipadessa cinerascens using electrospray ionization quadrupole time-of-flight tandem mass spectrometry and quantum chemical calculations

RATIONALE

Limonoids, a class of tetranortriterpenoids, exhibit various biological effects, such as insect antifeedant and growth regulating activities, antimicrobial activity, potent cell adhesion inhibitory effects, antimalarial activity, anticancer activities, and antioxidant activity. The potential application brings the need for reliable, fast and low-cost analysis of this class of compounds.

METHODS

Six cipadesin limonoids (1-6), including a pairs of isomers, from leaves and barks of Cipadessa cinerascens were investigated by electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-QTOF-MS/MS) in positive-ion mode. Characteristic processes were further studied by theoretical calculations.

RESULTS

1,3-Hydrogen rearrangement might play a significant role in the cleavage of -O- bridge bond in ring B and further produces some characteristic ions. For [M + Na](+) precursor ions, the product ion at m/z 133 might indicate the structure of ring A and the losses of CO(2) and AcOH occur readily. Interestingly, the radical product ion at m/z 460 from [M + Na](+) ions seems to be the characteristic ion for compound 1. A deuterium-labeling experiment supported the processes forming the radical ion. For [M + NH(4)](+) ions, high-abundance product ions resulting from sequential loss of AcOH can be observed. In addition, a pairs of isomers was unambiguously differentiated based on MS or MS/MS spectra.

CONCLUSIONS

In summary, sufficient information obtained from fragmentation experiments of [M + Na](+), [M + NH(4)](+) or [M + H](+) precursor ions is especially valuable for rapid identification of these limonoids or their metabolites in complex mixtures. The high-abundance radical product ion is of scientific interest.

Diversity of nitrogenase (nifH) genes pool in soybean field soil after continuous and rotational cropping

Diazotrophs diversity in soybean is a topic requiring thorough investigation since the previous researches have focused on only rice, forest, grass, water, etc. In this research, iron-only nitrogenase nifH gene was as genetic marker. PCR-RFLP was used to investigate the difference of diazotrophs community diversity in the soil from the continuous cropping (CC) (the 5-yr tilling of soybean) and the rotational cropping (RC) (soybean-corn) soils in the northeast of China. A total of 36 isolates were genetically characterized. Most of the isolates closely related to Azospirillum and Azotobacter. Eighty-six unique nifH gene sequences were obtained by cloning of the respective PCR products in two soil samples. It was found that the diversity of nifH genes in CC changed obviously compared with RC. Phylogenetic analysis indicated that most of the clones clustered together in a high homogeneity with some sequence retrieved from environmental representatives. The sequence diversity of nifH genes was high and the members of the Alphaproteobacteria were predominant in both samples. The experimental study also revealed the two non-proteobacterial diazotrophs, firmicutes and euryarchaeota. Through this study, it can be assumed that different tillage perhaps affected the nifH gene-containing population diversity.

[Polarographic behavior of latamoxef sodium and its trace determination]

In the medium of HCl-KCl (pH 1-2) by means of cyclic voltammetry and differential pulse polarography (DPP), the mechanism of the electrode reaction for latamoxef sodium (Shiomarin) at static mercury drop electrode (SMDE) and hanging mercury drop electrode (HMDE) has been proposed. A sensitive method for the determination of nanomolar concentration of latamoxef sodium by DPP was developed. The peak potential was -0.62 V (vs Ag/AgCl). The linear range was from 1 x 10(-8) to 8 x 10(-4) mol.L-1, the detection limit was ca. 4 x 10(-9) mol.L-1(tac = 90 s). The method was applied to the determination of latamoxef sodium in injection with satisfactory results. The possibility for the direct determination of latamoxef sodium in mimic urine sample was also studied.

Carbohydrate-fat exchange and regulation of hepatic cholesterol and plasma lipoprotein metabolism in the guinea pig

Adult female guinea pigs were fed semipurified diets containing increasing concentrations of saturated fat (2.5%, 7.5%, 15%, and 25% wt/wt) to determine effects of exchanging fat-carbohydrate calories on lipoprotein metabolism. Plasma very-low-density lipoprotein (VLDL) and high-density lipoprotein (HDL) did not vary but plasma low-density lipoprotein (LDL) concentrations increased with increasing fat calories. LDL cholesterol values were 42 +/- 25, 61 +/- 17, 92 +/- 25, and 98 +/- 21 mg/dL (mean +/- SD, n = 5), respectively. The relative proportion of cholesteryl ester increased and triacylglycerol (TAG) decreased for VLDL, LDL, and HDL as dietary fat increased. Plasma lecithin cholesterol acyltransferase (LCAT) activity was positively correlated with HDL cholesteryl ester content. Hepatic cholesterol and TAG concentrations were highest in animals fed 25% fat (P < .01). Hepatic apolipoprotein (apo) B/E receptor maximal binding capacity (Bmax) was 30% higher in animals fed 2.5% and 7.5% fat as compared with those fed 15% and 25% fat (P < .01) and inversely correlated with plasma LDL (r = -.85, P < .01). In contrast, HDL binding to guinea pig hepatic membranes exhibited a significant positive correlation with dietary fat quantity (r = .98, P < .001), consistent with a dose-response with increasing fat calories. The activity of hepatic 3-hydroxy-3-methyl glutaryl coenzyme A (HMG CoA) reductase was not affected by the amount of dietary fat, whereas the activity of acyl CoA:cholesterol acyltransferase (ACAT) was significantly increased in animals fed 25% fat (P < .05). Hepatic free-cholesterol and ACAT activity exhibited a positive correlation for all dietary groups (r = .75, P < .001). These results demonstrate that exchange of saturated dietary fat for carbohydrate calories results in significant modifications in the regulation of metabolic pathways that determine plasma LDL concentrations and hepatic cholesterol homeostasis.

Psyllium reduces plasma LDL in guinea pigs by altering hepatic cholesterol homeostasis

Male Hartley guinea pigs were fed semipurified diets containing various levels of psyllium and cholesterol to determine mechanisms by which psyllium lowers plasma low density lipoprotein (LDL) concentrations. Four diets were tested: control diets with 12.5% (w/w) cellulose, and psyllium diets in which cellulose was partially replaced with 7.5% (w/w) psyllium. Two levels of dietary cholesterol were used, either low (LC, 0.04%, w/w) or high (HC, 0.25%, w/w). Plasma LDL was reduced by 30 and 54% with psyllium intake in the LC and HC groups, respectively (P < 0.001), while plasma very low density lipoprotein (VLDL) was lowered only in the HC group (P < 0.001). Psyllium intake modified LDL composition and size compared to LDL from control animals with a lower proportion of cholesteryl ester and higher proportion of triacylglycerol, lower molecular weight, smaller diameter, and higher peak density (P < 0.001). Plasma VLDL from animals fed the psyllium-HC diet compared to the control-HC contained lower relative proportions of free and esterified cholesterol and a higher proportion of triacylglycerol, compositional characteristics similar to VLDL from animals fed LC diets. Hepatic free and esterified cholesterol concentrations were significantly reduced by psyllium an average of 25 and 55%, respectively, while hepatic HMG-CoA reductase activity was increased in both psyllium groups compared to the respective controls (P < 0.001). In addition, psyllium intake reduced hepatic acyl-CoA:cholesterol acyltransferase (ACAT) activity in both the LC and HC groups (P < 0.001) and increased hepatic membrane apoB/E receptor number (Bmax) by 17 and 52% for animals fed LC and HC diets, respectively (P < 0.005). Significant psyllium-induced increases in cholesterol 7 alpha-hydroxylase of 4- and 1.6-fold were also observed in animals fed the LC and HC diets respectively (P < 0.001). These results indicate that psyllium generates a negative cholesterol balance across the liver which results in induction of cholesterol 7 alpha-hydroxylase and HMG-CoA reductase and suppression of ACAT activities, upregulation of apoB/E receptors, and secretion of smaller VLDL particles, metabolic alterations that contribute to a lowering of plasma LDL cholesterol levels.

Guar gum effects on plasma low-density lipoprotein and hepatic cholesterol metabolism in guinea pigs fed low- and high-cholesterol diets: a dose-response study

Guinea pigs were fed semipurified diets containing either 0% or 12.5% guar gum (GG) with 0.04% cholesterol or increasing concentrations of GG (0%, 2.5%, 5%, 7.5%, 10%, and 12.5%) with 0.25% cholesterol (by wt). Compared to the 0% GG diet with 0.04% cholesterol, intake of the 12.5% GG diet with 0.04% cholesterol lowered plasma low-density-lipoprotein (LDL) concentrations, the ratio of LDL cholesteryl ester to protein, hepatic cholesterol concentrations, and the activity of acyl-CoA:cholesterol acyltransferase (ACAT), and increased 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase activity and hepatic apo B/E receptor number (P < 0.01). Intake of GG by animals fed 0.25% cholesterol diets resulted in modest effects on hepatic cholesterol pools and plasma LDL concentrations; however, significant negative correlations were found between both plasma LDL cholesterol and hepatic free cholesterol concentrations with the amount of dietary GG (P < 0.05). Hepatic HMG-CoA reductase was suppressed by the 0.25% cholesterol intake, and GG did not reverse this suppression. In contrast, ACAT activity was negatively correlated with the amount of dietary GG (P < 0.05), and GG intake increased the number of hepatic apo B/E receptors at all intakes with the 0.25% cholesterol diets. These results demonstrate that intake of GG significantly alters endogenous cholesterol metabolism by decreasing hepatic cholesterol pools, altering hepatic cholesterol homeostasis, and reducing plasma LDL concentrations.

Citrus pectin and cholesterol interact to regulate hepatic cholesterol homeostasis and lipoprotein metabolism: a dose-response study in guinea pigs

Guinea pigs were fed increasing concentrations of citrus pectin (CP) (0-12.5%, wt/wt) with low (LC, 0.04%) or high (HC, 0.25%) cholesterol. Animals fed LC diets had reduced plasma LDL concentrations with 10% and 12.5% CP and hepatic membrane apolipoprotein B/E receptor expression increased with high dosages of CP. Hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity increased with 12.5% CP whereas hepatic cholesterol concentrations and acyl-CoA:cholesterol acyltransferase (ACAT) activity were not different. In contrast, with HC diets, plasma LDL concentrations were reduced in a dose-response manner by 29%, 30%, and 67% with 7.5%, 10%, and 12.5% CP intake (P < 0.001) and apolipoprotein B/E receptor number was increased and inversely correlated with plasma LDL in the HC group (r = -0.81, P < 0.005). Animals fed HC diets had a dose-dependent decrease in hepatic cholesterol and ACAT activity, with intake of 12.5% CP having the major effect. Hepatic HMG-CoA reductase activity was suppressed by HC diets and only intake of 12.5% CP reversed this suppression. The most significant effects of CP on hepatic cholesterol, enzymes of hepatic cholesterol homeostasis, and the apolipoprotein B/E receptor were in animals fed the HC diets. These metabolic alterations partially explain the reduced plasma LDL of guinea pigs fed large amounts of CP.