Lipid transfers to HDL are diminished in long-term bedridden patients: association with low HDL-cholesterol and increased inflammatory markers

Plasma lipids have been extensively studied in sedentary and in subjects practicing exercise training, but not in extreme inactivity as occurs in bedridden patients. This is important for the care of bedridden patients and understanding the overall plasma lipid regulation. Here, we investigated plasma lipids, lipid transfers to HDL and inflammatory markers in bedridden patients. Fasting blood samples were collected from 23 clinically stable bedridden patients under long‐term care (>90 days) and 26 normolipidemic sedentary subjects, paired for age and gender. In vitro transfer of four lipids to HDL was performed by incubating plasma with donor nanoparticles containing radioactive lipids. Total (193 ± 36 vs 160 ± 43, p = 0.005), LDL (124 ± 3 vs 96 ± 33 p = 0.003) and HDL‐cholesterol (45 ± 10 vs 36 ± 13, p = 0.008), apolipoprotein A‐I (134 ± 20 vs 111 ± 24, p = 0.001) and oxidized LDL (53 ± 13 vs 43 ± 12, p = 0.011) were lower in bedridden patients, whereas triglycerides, apolipoprotein B, CETP and LCAT were equal in both groups. Transfers of all lipids, namely unesterified cholesterol, cholesterol esters, triglycerides and phospholipids, to HDL were lower in bedridden patients, probably due to their lower HDL‐cholesterol levels. Concentrations of IL‐1β, IL‐6, IL‐8, HGF and NGF were higher in bedridden patients compared to sedentary subjects. In conclusion, inactivity had great impact on HDL, by lowering HDL‐cholesterol, apolipoprotein A‐I and thereby cholesterol transfers to the lipoprotein, which suggests that inactivity may deteriorate HDL protection beyond the ordinary sedentary condition.     

Natural Rumen‐Derived trans Fatty Acids Are Associated with Metabolic Markers of Cardiac Health

Evidence suggests that industrial trans fatty acids (iTFA) impair lipid profiles while ruminant trans fatty acids (rTFA) may lower insulin resistance and blood pressure. The objective of this article was to determine if the plasma phospholipid percentage of rTFA is associated with a favorable cardiometabolic profile. We collected fasting blood samples from 200 individuals from Quebec city (QC, Canada) aged from 18 to 55 years old, including 100 obese (BMI ≥ 30 kg m^?2) and 100 non‐obese (BMI < 30 kg m^?2) men and women. Fatty acid levels in plasma phospholipids were determined using gas chromatography. After separating the subjects into two groups, according to the median percentage of rTFA in plasma phospholipids, participants in the group with higher percentages of rTFA (0.86 ± 0.24 %) had higher adiponectin levels (p = 0.01) and a lower blood pressure (systolic, p = 0.005; diastolic, p = 0.04). In contrast, concentrations in plasma phospholipids of elaidic acid, a major iTFA, are positively correlated with glycemia in non‐obese subjects (p = 0.01) and with both triacylglycerol (TAG) (p = 0.0007) and total cholesterol (TC) (p = 0.009) in obese subjects. These data suggest that rTFA may have beneficial effects on cardiometabolic risk factors conversely to their counterpart iTFA. Dietary sources of TFA should be taken into account in future cardiometabolic studies.     

Relationships between Very Low-Density Lipoproteins–Ceramides, −Diacylglycerols,and –Triacylglycerols in Insulin-Resistant Men

This short report describes the relationships between concentrations of ceramides (CER), diacylglycerols (DAG), triacylglycerols (TAG) in very low-density lipoproteins (VLDL) particles, and hepatic lipid accumulation. VLDL particles were isolated from male subjects (n = 12, mean ± SD, age 42.1 ± 5.4 years, BMI 37.4 ± 4.1 kg/m², ALT 45 ± 21 U/L) and apolipoprotein B100 (apoB100), VLDL-TAG, -CER, and -DAG quantified. The contents of all three lipids were highly correlated with VLDL particle number (r ≥ 0.768, p ≤ 0.003). The molar quantity of VLDL-TAG was 3× that of DAG and 137× that of CER (14,053 ± 5714, 5004 ± 2714, and 105 ± 49 mol/mol apoB100, respectively). Reduced VLDL-CER concentrations were associated with both higher insulin levels (r = −0.645, p = 0.024) and intrahepatic-TAG (r = −0.670, p = 0.017). In fatty liver, the secretion of hepatic TAG, CER, and DAG may be suppressed and contribute to intrahepatic lipotoxicity. The mechanisms by which hepatic-CER and -DAG synthesis and assembly into VLDL is coordinately controlled with TAG will be important in understanding the emerging role of elevated CER contributing to cardiometabolic disease.     

Thermophysical properties of laboratory-prepared corn/wheat dried distillers grains and dried distillers solubles dehydrated with superheated steam and hot air

The objective of this study was to dry–wet distillers grains and centrifuged solubles and to examine the effect of two different drying media, superheated steam and hot air, at different drying temperatures (110, 130, and 160°C), moisture contents (5–30% wb), and percentages of solubles’ presence (0 or 100%) on some thermophysical properties of laboratory-prepared corn/wheat dried distillers co-products, including geometric mean diameter (d_g), particle density (ρ_p), bulk density (ρ_b), bulk porosity (?_b), specific heat (C), effective thermal diffusivity (α_eff), and bulk thermal conductivity (λ_b). The values of d_g of corn/wheat dried distillers co-products ranged from 0.358 ± 0.001 to 0.449 ± 0.001 mm. Experimental values of ρ_p, ρ_b, and ?_b varied from 1171 ± 6 to 1269 ± 3 kg m^?3, from 359 ± 7 to 605 ± 5 kg m^?3, and from 0.54 ± 0.01 to 0.71 ± 0.01 kg m^?3, respectively. The values of α_eff were between 0.58 × 10^?7 and 0.93 × 10^?7 m² s^?1. The calculated values of C ranged from 1887 ± 11 to 2599 ± 19 J kg^?1 K^?1, and the values of λ_b of corn/wheat dried distillers co-products ranged from 0.06 ± 0.01 to 0.09 ± 0.01 W m^?1 K^?1. Multiple linear regression prediction models were developed to predict the changes in d_g, ρ_p, ρ_b, ?_b, C, α_eff, and λ_b of laboratory-prepared corn/wheat dried distillers co-products with different operational factors.     

Effect of grass vs. concentrate feeding on the fatty acid profile of different fat depots in lambs

The aim of this study was to produce high‐quality meat from lambs under different feeding conditions, as measured by the accumulation of n‐3 fatty acids and conjugated linoleic acids (CLA) in muscle and subcutaneous fat. In total, 13 male crossbred lambs (Black Head×Gotland), each at 24 kg live weight, were divided into two feeding groups. Lambs were kept either on pasture (pasture grazing, n = 6) or in the stable (concentrate feeding, n = 7). The linolenic acid (C18:3n‐3) contained in the grass was absorbed and deposited into the different lipid classes of muscle and subcutaneous fat. The proportion of total n‐3 fatty acids in the different lipids of grazing lambs was significantly (p = 0.05) higher compared to that in concentrate‐fed lambs. The n‐6/n‐3 ratio (mean ± SEM) in muscle of grazing lambs was 1.2 ± 0.09 in contrast to 2.3 ± 0.09 (p = 0.05) of the animals kept in the stable. In subcutaneous fat, this ratio was 0.9 ± 0.2 in lambs kept on pasture versus 3.5 ± 0.2 (p = 0.05) after indoor keeping. The relative concentration of C18:1trans‐11 in total muscle lipids, phospholipids, triacylglycerols and subcutaneous fat was significantly increased by grass feeding compared to concentrate feeding. Significant influences of feeding were shown for saturated fatty acids. In concentrate‐fed lambs, a lower content of saturated fatty acids was detected. The proportion of CLAcis‐9,trans‐11 (1.9 ± 0.2% vs. 1.1 ± 0.1% in muscle, 2.5 ± 0.2% vs. 1.4 ± 0.2% in subcutaneous fat, 0.7 ± 0.04% vs. 0.4 ± 0.04% in phospholipids) in lambs was significantly (p = 0.05) higher after grazing than after concentrate feeding, respectively.     

Plasma Phytosterol Half‐Life and Levels Are Increased in Very Low Birth Weight Preterm Infants with Parenteral Nutrition‐Associated Cholestasis

Parenteral nutrition‐associated cholestasis (PNAC) has been linked to plasma accumulation of phytosterols in infants receiving vegetable‐oil‐based lipid emulsions (LE). To date, information on the ability of infants with PNAC to metabolize intravenous (IV) phytosterols has been very limited. We characterized plasma phytosterol half‐life in very low birth weight (VLBW) preterm infants with PNAC. As part of a prospective cohort study, VLBW infants with PNAC underwent serial blood sample measurements of sitosterol (Sito), campesterol (Camp), and stigmasterol (Stigma). Infants without PNAC served as controls (CTRL, control infants). Thirty‐seven PNAC infants and 14 CTRL were studied. On PN day 7 and PN day 14, PNAC infants had higher plasma phytosterol concentrations compared to those of CTRL (p < 0.05). A significant and positive correlation was found between plasma Camp, Stigma, Sito concentrations, and IV phytosterol intake from birth to PN day 7 (p = 0.001, p = 0.001, and p = 0.005, respectively). Stigma concentration was positively correlated with conjugated bilirubin on PN day 7 (p = 0.012). After stopping IV LE, half‐lives of Camp, Stigma, and Sito became significantly longer in PNAC infants than in CTRL (Camp: 18.8 ±6.2 vs 11.8 ±3.0 days, p = 0.001; Stigma: 13.8 ±5.8 vs 9.4 ±3.4 days, p = 0.023; Sito: 15.3 ±5.0 vs 9.8 ±3.0 days, p = 0.002). In conclusion, phytosterols increased earlier during PN and were eliminated slowly after stopping IV LE in PNAC infants than in CTRL. The Stigma concentration on PN day 7 could represent an early marker of cholestasis. Our results provide additional evidence on the relationship between IV phytosterols and PNAC.     

In vivo evaluation of the effects of continuous exercise on skeletal muscle triglycerides in trained humans

Magnetic resonance spectroscopy (¹H MRS) and imaging (MRI) were used to investigate the effects of a bout of moderate prolonged exercise on intra (IMCL)- and extramyocellular lipid (EMCL) utilization in the soleus, tibialis anterior, and gastrocnemius muscles of five trained human subjects. MRI and ¹H MRS measurements were obtained before and after a 90 min run on a calibrated treadmill at a velocity corresponding to 64±1.5% of each subjects' maximal rate of oxygen consumption. There were significant decreases in IMCL following exercise in the tibialis (pre: 22.37±4.33 vs. post: 15.16±3.25 mmol/kg dry wt; P<0.01) and soleus (pre: 36.93±1.45 vs. post: 29.85 ±2.44 mmol/kg dry wt; P<0.01) muscles. There was also a decrease in the gastrocnemius muscle, although this did not reach the level of significance (pre: 33.78±5.35 vs. post: 28.48±5.44 mmol/kg dry weight; P<0.10). No significant changes were observed in EMCL or subcutaneous fat. In conclusion, this study showed that IMCL were significantly utilized in the tibialis and soleus muscles of aerobically endurance-trained humans. The absence of significant utilization of IMCL in the gastrocnemius may reflect differences in fiber type and/or intensity of contraction for each muscle group.     

Influence of different reactor types on Nannochloropsis oculata microalgae culture for lipids and fatty acid production

Greenhouse gases emitted into the atmosphere by burning of fossil fuels cause global warming. One option is obtaining biodiesel. Nannochloropsis oculata was cultured under different light intensities and reactors at 25°C for 21 days with f/2 medium to assess their effects on cell density, lipid, and fatty acids (FAs). N. oculata improved cell density on fed-batch glass tubular reactor (7 L) at 200 μmol E m⁻² s⁻¹, yielding 3.5 × 10⁸ cells ml⁻¹, followed by fed-batch Erlenmeyer flask (1 L) at 650 μmol E m⁻² s⁻¹ with 1.7 × 10⁸ cells ml⁻¹. The highest total lipid contents (% g lipid × g dry biomass⁻¹) were 44.4 ± 0.8% for the reactor (1 L) at 650 μmol E m⁻² s⁻¹ and 35.2 ± 0.2% for the tubular reactor (7 L) at 200 μmol E m⁻² s⁻¹, until twice as high compared with the control culture (Erlenmeyer flask 1 L, 80 μmol E m⁻² s⁻¹) with 21.2 ± 1%. Comparing the total lipid content at 200 μmol E m⁻² s⁻¹, tubular reactor (7 L) and reactor 1 L achieved 35.2 ± 0.2% and 28.3 ± 1%, respectively, indicating the effect of shape reactor. The FAs were affected by high light intensity, decreasing SFAs to 2.5%, and increased monounsaturated fatty acids + polyunsaturated fatty acids to 2.5%. PUFAs (20:5n-3) and (20:4n-3) were affected by reactor shape, decreasing by half in the tubular reactor. In the best culture, fed-batch tubular reactor (7 L) at 200 μmol E m⁻² s⁻¹ contains major FAs (16:0; 38.06 ± 0.16%), (16:1n-7; 30.74 ± 0.58%), and (18:1n-9; 17.15 ± 0.91%).     

Curcumin Attenuates Lipopolysaccharide‐Induced Hepatic Lipid Metabolism Disorder by Modification of m6A RNA Methylation in Piglets

N⁶‐methyladenosine (m⁶A) regulates gene expression and affects cellular metabolism. In this study, we checked whether the regulation of lipid metabolism by curcumin is associated with m⁶A RNA methylation. We investigated the effects of dietary curcumin supplementation on lipopolysaccharide (LPS)‐induced liver injury and lipid metabolism disorder, and on m⁶A RNA methylation in weaned piglets. A total of 24 Duroc × Large White × Landrace piglets were randomly assigned to control, LPS, and CurL (LPS challenge and 200 mg/kg dietary curcumin) groups (n = 8/group). The results showed that curcumin reduced the increase in relative liver weight as well as the concentrations of aspartate aminotransferase and lactate dehydrogenase induced by LPS injection in the plasma and liver of weaning piglets (p < 0.05). The amounts of total cholesterol and triacylglycerols were decreased by curcumin compared to that by the LPS injection (p < 0.05). Additionally, curcumin reduced the expression of Bcl‐2 and Bax mRNA, whereas it increased the p53 mRNA level in the liver (p < 0.05). Curcumin inhibited the enhancement of SREBP‐1c and SCD‐1 mRNA levels induced by LPS in the liver. Notably, dietary curcumin affected the expression of METTL3, METTL14, ALKBH5, FTO, and YTHDF2 mRNA, and increased the abundance of m⁶A in the liver of piglets. In conclusion, the protective effect of curcumin in LPS‐induced liver injury and hepatic lipid metabolism disruption might be due to the increase in m⁶A RNA methylation. Our study provides mechanistic insights into the effect of curcumin in protecting against hepatic injury during inflammation and metabolic diseases.     

Modulation of renal injury in pcy mice by dietary fat containing n−3 fatty acids depends on the level and type of fat

Low-fat diets and diets containing n−3 fatty acids (FA) slow the progression of renal injury in the male Han:Sprague-Dawley (SPRD)-cy rat model of polycystic kidney disease. To determine whether these dietary fat effects are similar in females and in another model of renal cystic disease, in this study we used both male and female pcy mice to examine the effects of fat level and type on disease progression. Adult pcy mice were fed 4, 10, or 20 g soybean oil/100 g diet for 130 d in study 1. In study 2, weanling pcy mice were fed high or low levels of fat rich in 18∶2n−6 (corn oil, CO) 18∶3n−3 (flaxseed oil/CO 4∶1 g/g, FO), or 22∶6n−3 (algal oil/CO 4∶1 g/g, DO) for 8 wk. In adult pcy mice, low-compared with high-fat diets lowered kidney weights (2.4±0.2 vs. 3.1±0.2 g/100 g body weight, P=0.006) and serum urea nitrogen (SUN) (9.6±0.6 vs. 11.9±0.6 mmol/L, P=0.009), whereas in young pcy mice it reduced renal fibrosis volumes (0.44±0.04 vs. 0.62±0.04 mL/kg body weight, P<0.0001). FO feeding in young pcy mice mitigated the detrimental effects of high fat on fibrosis while not altering kidney size, function, and oxidative damage when compared with the CO-fed mice. In contrast, DO-compared with CO-fed mice had higher kidney weights (2.64±0.07 vs. 2.24±0.08 g/100 g body weight, P=0.005), SUN (9.4±0.57 vs. 7.0±0.62 nmol/L, P<0.0001), and cyst volumes (7.9±0.28 vs. 6.2±0.30 mL/kg body weight, P<0.0001) and similar levels of oxidative damage and fibrosis. The FA compositions of the diets were reflected in the kidneys: 18∶2n−6, 18∶3n−3, and 22∶6n−3 were the highest in the CO, FO, and DO diets, respectively. Dietary effects on kidney disease progression were similar in males and females. A low-fat diet slows progression of renal injury in male and female pcy mice, consistent with findings in the male Han:SPRD-cy rat. Dietary fat type also influenced renal injury, with flaxseed oil diets rich in 18∶3n−3 slowing early fibrosis progression compared with diets rich in 18∶2n−6 or in 22∶6n−3.     

An Oral Mixed Fat Load Is Followed by a Modest Anti-inflammatory Adipocytokine Response in Overweight Patients with Metabolic Syndrome

We investigated the postprandial changes in plasma levels of adipocytokines in overweight patients with metabolic syndrome after an oral fat load. After an oral fat load and during a prolonged fast, blood was drawn at 0, 2, 3, 4 and 8 h for measurement of adiponectin, adipsin, cathepsin S, chemerin, hepatic growth factor, interferon‐γ‐inducible protein‐10, leptin, macrophage chemoattractant protein‐1, macrophage migration inhibitory factor, nerve growth factor, retinol binding protein‐4, resistin, serum amyloid A1, tissue inhibitor of metalloproteinase‐1 and thrombopoietin using a microbead‐based Luminex assay. Area under the curves (AUC) were calculated and compared. Plasma adiponectin levels were higher after an oral fat load compared to fasting at t = 2 h (950 ± 513 vs. ?1,881 ± 713 ng/ml) while the plasma levels for adipsin (?9 ± 5 vs. 16 ± 5 ng/ml), chemerin (?122 ± 35 vs. 13 ± 21 ng/ml), SAA‐1 (?391 ± 213 vs. 522 ± 173 ng/ml) and TPO (?335 ± 144 vs. 622 ± 216 ng/ml) were lower after an oral fat load compared to fasting. The baseline corrected AUC for IP‐10 was higher after fat load compared to fasting (median ?116 pg h/ml; IQR ?270 to 10 vs. ?21 pg h/ml; IQR ?136 to 418 (p = 0.047). In conclusion, in overweight male subjects with the metabolic syndrome, an oral fat load is accompanied with a modest anti‐inflammatory response of adipose tissue‐derived adipocytokines.     

Divergent incorporation of dietary trans fatty acids in different serum lipid fractions

Trans fatty acids may be involved in atherosclerotic vascular diseases. We investigated the incorporation of dietary trans fatty acids and oleic acid into the serum triglycerides (TG), cholesterol esters (CE), and phospholipids (PL). Fourteen healthy female volunteers, aged 23.2±3.1 yr (mean±SD), body mass index 20.8±2.1 kg/m² participated in this study. All subjects consumed both a trans fatty acid-enriched diet (TRANS diet) and an oleic acid-enriched diet (OLEIC diet) for 4 wk according to a randomized crossover design. Both experimental diet periods were preceded by consumption of a baseline diet for 2 wk which supplied 37% of total energy (E%) as fat: 18 E% from saturated fatty acids (SFA), 12 E% from monounsaturated fatty acids, and 6 E% from polyunsaturated fatty acids. Five E% of the SFA in the baseline diet was replaced by trans fatty acids (18∶1 t and 18∶2 c,t+18∶2t,t, where c is cis and t is trans) in the TRANS diet and by oleic acid (18∶1n-9) in the OLEIC diet. After the TRANS diet, the proportions of 18∶1t and 18∶2t increased (P <0.001) in all serum lipid fractions analyzed. The increase of 18∶1 t in TG and PL (1.80±0.28 vs. 5.26±1.40; 1.07±0.34 vs. 3.39±0.76 mol% of total fatty acids, respectively) was markedly higher than that in CE (0.44±0.07 vs. 0.92±0.26), whereas that of 18∶2t was nearly the same in all three fractions. The proportions of palmitic, stearic, arachidonic, and eicosapentaenoic acids in TG, CE, and PL and that of oleic acid in TG and CE were decreased when compared with the baseline value. In contrast, the proportion of palmitoleic acid in TG and PL and that of linoleic acid in PL increased on the TRANS diet. After consumption of the OLEIC diet, the proportion of oleic acid increased in all three lipid fractions analyzed, and the percentage increase was nearly the same in all fractions. In contrast, the proportions of 18∶1 t in TG and PL and 18∶2 t in TG and CE decreased when compared with the baseline value. In conclusion, a moderate increase in dietary trans fatty acids resulted in a marked incorporation into serum lipids and decreased the conversion of linoleic acid to its more unsaturated long-chain metabolites. Analysis of 18∶1 t from serum TG and PL seems to reflect reliably the dietary intake of this fatty acid.     

Effect of a weight loss intervention on anthropometric measures and metabolic risk factors in pre- versus postmenopausal women

Background

The present study examines changes in body weight, fat mass, metabolic and hormonal parameters in overweight and obese pre- and postmenopausal women who participated in a weight loss intervention.

Methods

Seventy-two subjects were included in the analysis of this single arm study (premenopausal: 22 women, age 43.7 ± 6.4 years, BMI 31.0 ± 2.4 kg/m²; postmenopausal: 50 women, age 58.2 ± 5.1 years, BMI 32.9 ± 3.7 kg/m²). Weight reduction was achieved by the use of a meal replacement and fat-reduced diet. In addition, from week 6 to 24 participants attended a guided exercise program. Body composition was analyzed with the Bod Pod^®. Blood pressures were taken at every visit and blood was collected at baseline and closeout of the study to evaluate lipids, insulin, cortisol and leptin levels.

Results

BMI, fat mass, waist circumference, systolic blood pressure, triglycerides, glucose, leptin and cortisol were higher in the postmenopausal women at baseline. Both groups achieved a substantial and comparable weight loss (pre- vs. postmenopausal: 6.7 ± 4.9 vs 6.7 ± 4.4 kg; n.s.). However, in contrast to premenopausal women, weight loss in postmenopausal women was exclusively due to a reduction of fat mass (-5.3 ± 5.1 vs -6.6 ± 4.1 kg; p < 0.01). In premenopausal women 21% of weight loss was attributed to a reduction in lean body mass. Blood pressure, triglycerides, HDL-cholesterol, and glucose improved significantly only in postmenopausal women whereas total cholesterol and LDL-cholesterol were lowered significantly in both groups.

Conclusion

Both groups showed comparable weight loss and in postmenopausal women weight loss was associated with a pronounced improvement in metabolic risk factors thereby reducing the prevalence of metabolic syndrome.     

Potential fuel oils from the microalga Choricystis minor

BACKGROUND: Continuous culture of the freshwater microalga Choricystis minor was investigated for possible use in producing lipid feedstock for making biofuels. The effects of temperature (10–30 °C) and dilution rate (0.005–0.017 h^?1) on lipid productivity in a nutrient sufficient medium in a 4 L stirred tank bioreactor under continuous illumination at an incident irradiance level of 550 µE · m^?2s^?1 and a controlled pH of 6 under carbon dioxide supplemented conditions are reported. RESULTS: The maximum lipid productivity was 82 mg L^?1 d^?1 at 25 °C and a dilution rate of 0.014 h^?1. Lipid contents of the biomass were 21.3 ± 1.7 g per 100 g of dry biomass, irrespective of the culture temperature and dilution rate. After the biomass had been grown in nutrient sufficient conditions in continuous culture, it was recovered and subjected to various postharvest treatments. With the best postharvest treatment, the neutral lipid contents of the algal biomass were raised ～6‐fold relative to untreated biomass. CONCLUSION: At 82 mg L^?1 d^?1, or 21 000 L ha^?1 year^?1, the lipid productivity of C. minor was nearly four times the lipid productivity of oil palm, a highly productive crop. Therefore, C. minor is potentially a good source of renewable lipid feedstock for biofuels. Copyright © 2009 Society of Chemical Industry     

Optical rotation of dilute aqueous xanthan solutions at elevated hydrostatic pressure

The optical rotation of dilute aqueous xanthan solutions of ultrasonically depolymerized xanthan have been measured in the pressure range from 0.1 to 50 MPa. This was achieved using a high-pressure cell in a spectropolarimeter of original design. The conformational melting temperature T_m of xanthan was found to decrease with increasing pressure. The pressure coefficients of the melting temperature at constant ionic strengths, I, was found to be (ΔT_m/Δp)_I = ?(9.5 ± 4.0) 10^?8 K Pa^?1 and (ΔT_m/Δp)_I = ?(20 ± 10) 10^?8 K Pa^?1 for solution ionic strengths of 10 mM NaCl and 25mM NaCl, respectively. The largest shift in T_m of xanthan for an increase in hydrostatic pressure from 0.1 to 50 MPa is less than ?10 K. The observed decrease in conformational transition temperature can have significant implications when xanthan is used in polymer or micellar flooding processes in high-salinity, high-temperature oil reservoirs where the reservoir temperature is close to the structural transition temperature at ambient pressure.     

The Crystal and Molecular Structure of Kinamycin C p-Bromobenzoate

The molecular structure of kinamycin C has been determined by means of an X-ray study of its p-bromobenzoate derivative, C₃₁H₂₃N₂O₁₁Br. The crystals are monoclinic, P2₁, with four molecules of the derivative and four molecules of benzene in a unit cell of dimensions: a = 18.404 ± 0.005, b = 21.299 ± 0.004, c = 9.049 ± 0.001 Å, and β = 90.07 ± 0.03°. Reflection intensities were measured visually from equi-inclination Weissenberg photographs taken with Cu Ka radiation. The structure was solved by the heavy-atom method, and was refined by the block-diagonal-matrix least-squares method using anisotropic temperature factors for all the atoms. The final R factor is 8.9%. The stereostructures of the two crystallographically independent molecules are almost identical. The skeleton of the molecule is made up of four fused rings: two of these form a 1,4-naphthoquinone system and the rest are a pyrrole and a cyclohexene ring. A cyano group is bonded to the nitrogen atom of the pyrrole ring, which is rather unusual in an antibiotic.     

Phospholipid profile and production of prostanoids by murine colonic epithelium: Effect of dietary fat

Dietary fat and abnormal production of various prostanoids have been linked to various disease states of the large bowel, including cancer of the colon. Studies were conducted to determine the effect of dietary fat (beef tallow or corn oil) on the lipid composition and prostanoid production of the murine colon. Female C57BL/6J mice were fed high-fat (HF) diets (47% of calories as fat) or low-fat (LF) diets (10% of calories as fat). After four wk of dietary treatment, the mucosa was scraped, and lipids were extracted from the mucosal and muscle layers. The fat content of the diets did not significantly alter the amount of phospholipid (PL) or neutral lipid in the colonic tissue. However, the HF affected the PL profile of the colonic mucosa. For example, the ratio of phosphatidylcholine (PC) to phosphatidylethanolamine (PE) was significantly higher for both the HF groups compared with that of the two LF groups (0.76±0.15 and 0.80±0.13 vs 0.31±0.20 and 0.34±0.18). Production of 13,14-dihydro-15-keto-PGE₂ (measured as bicyclic PGE₂) and TXB₂ (a stable metabolite of TXA₂) and PGF_1α (a stable metabolite of PGI₂) was unaffected by the dietary treatments. The muscle had a different PL profile (PC:PE is 2.6±0.1) than the mucosa and contributed a larger proportion of the prostanoids formed. This study demonstrates that the phospholipid polar head group composition of normal colonic mucosa is altered by dietary fat, but the ability of the mucosa to synthesize metabolites of PGE₂, TXA₂ and PGI₂ is not affected. ARC Contribution No. 1504.     

Thermic effect of feeding: orange juice vs. a protein drink (240 kcal)

We investigated the thermic effect of feeding (TEF) equicaloric (1004.16 kJ) portions of randomly provided fresh squeezed orange juice (17.45 oz) and Protein Rush_TM (40g protein, 17 oz). Eight subjects (5 women, 3 men; 25.8 ± 9.2 yrs, 174.9 ± 12.4 cm, 71.5 ± 17.5 kg) reported to the lab on subsequent mornings and underwent 30-minutes of resting metabolic rate testing, followed by 2-minutes of drink ingestion, followed by 60-minutes of supine rest. Data were collected via a metabolic cart and ventilated hood. Resting data were subtracted from all post-ingestion measures. Within groups the rate of O₂ uptake (l min^-1) increased significantly for protein (+29%, p = 0.03) but not for orange juice (+21%, p = 0.11); when expressed as ml ^. kg^-1 min^-1, both groups had significant increases (p < 0.005). Between groups O₂ uptake measurements over the 1-hour period revealed a 21% difference between orange juice (2.66 ± 0.6 liters) and protein (3.36 ± 0.9 liters) that did not reach statistical significance (p = 0.10). Energy expenditure (kJ) determined via the respiratory exchange ratio (RER) revealed orange juice at (60.8 ± 10.1 kJ) and protein (63.7 ± 20.0 kJ) were 5% different, also non-significant (p = 0.72). The RER averaged over the 60-min TEF period was significantly different between orange juice (0.868 ± 0.07) and protein (0.773 ± 0.04) (p = 0.005). Sample size calculations indicate that 14 subjects would reveal statistical significance for O₂ uptake yet 163 subjects would be required for energy expenditure differences between drinks. We suggest the potential for bias in selecting a measure of TEF from data within- and between-groups and, O₂ uptake vs. energy expenditure.

     

Yield and Quality Characteristics of Rendered Chicken Oil for Biodiesel Production

Whole dead poultry birds obtained from commercial layer farms were assessed for fat in the whole carcass and then dry rendered in three different rendering regimens T₁, T₂ and T₃ (temperature = 120, 130 and 140 °C and shell pressure = 1, 2 and 3 kg/cm² respectively) and the effect on the yield and quality of the rendered chicken oil were studied. The overall fat percentage of the whole dead poultry carcass was 14.55 ± 0.17 % and the fat content of ‘greaves’ was 14.49 ± 0.38 %. In the dry batch rendering trials, the mean overall fat recovery was 24.46 ± 1.19, 26.78 ± 3.14 and 22.42 ± 2.32 % and the overall fat yield was 3.52 ± 1.72, 3.84 ± 0.44 and 3.22 ± 0.33 % of the carcass weight in T₁, T₂ and T₃ respectively. Solvent extraction of fat could recover 96.10 ± 0.14 % of fat from ‘greaves’ which was significantly higher than the mechanical centrifugation method. Among the quality characteristics of the rendered chicken oil (RCO), moisture content ranged from 0.61 % (T₂) to 1.09 % (T₁) and the mean specific gravity was 0.91 at 30 °C. The FFA values of RCO obtained from the T₃ rendering regimen were significantly (p < 0.05) higher than the FFA values of T₂ and T₁. The mean acid value, iodine number, peroxide value, saponification value and unsaponifiable matter present in RCO showed no significant difference. The fatty acid profile and calorific values were studied. The RCO was converted to biodiesel by transesterification and the physico-chemical properties of the biodiesel were studied and compared with the Indian biodiesel specification.     

Analysis of structural,morphological alterations,wettability characteristics and adhesion to enamel after various surface conditioning methods

Minimal invasive dental reconstructions and orthodontic appliances are bonded to enamel without removing the enamel with rotating instruments but the top layer of enamel may be partially aprismatic and impair adhesion. The objectives of this study were to investigate the effect of mechanical surface conditioning methods for removing enamel on its structural, morphological alterations, wettability characteristics, and adhesion of resin-based cement to the conditioned surfaces. Maxillary human incisors (N = 40, n_quadrant = 160) were obtained and coronal sections were embedded in acrylic with their labial surfaces exposed. The teeth were randomly divided into four groups and the enamel surface of each tooth was divided into four quadrants. The surfaces were conditioned in a clockwise manner by one of the following methods: (1) Non-conditioned enamel acted as the control group (C); (2) Silicone-coated disk (Sof-Lex disc, Black, 3 M ESPE) (SD); (3) Diamond bur at slow speed (DB) and (4) Airborne particle abrasion (50 μm Al₂O₃, 2 bar, 5 s) (AA). Surface roughness was measured at each quadrant using a non-contact digital profilometer and contact angle measurements were performed using a goniometer. Enamel surfaces were then etched with 37% H₃PO₄ for 60 s and roughness and wettability measurements were repeated. The enamel surfaces in each quadrant received resin composite luting cement (Variolink II, Ivoclar Vivadent) incrementally in a polyethylene mold (diameter: 1 mm²; height: 4 mm) and photopolymerized. The specimens were stored in distilled water for 24 h at 37 °C until the testing procedures and then shear force was applied to the adhesive interface until failure occurred in a Universal Testing Machine (0.5 mm/min). Microshear bond (μSBS) was calculated by dividing the maximum load (N) by the bonding surface area of the resin cement. Representative enamel surfaces were analyzed under the scanning electron microscope (SEM) (x5000) to assess the surface morphology. Failure types were analyzed using optical microscope and SEM. Data (MPa) were analyzed using one-way ANOVA and Tukey`s test for each parameter and Linear model for group comparisons (α = 0.05). Surface conditioning method significantly affected the adhesion results (p < 0.001), surface roughness (p = 0.017), and contact angle (p < 0.001). Interaction terms were significant (p > 0.05). AA (338 ± 182) created significantly higher surface roughness compared to SD (308 ± 180) and DB (242 ± 197) (p < 0.05). After etching with 37% H₃PO₄, DB (307 ± 223) resulted in significantly lower roughness than those of SD (385 ± 173) and AA (414 ± 193) (p < 0.05). AA (40 ± 11) delivered significantly lower contact angle compared to those of SD (61 ± 9) and DB (59 ± 10). After etching with 37% H₃PO₄, AA (42 ± 10) and DB (50 ± 10) presented the lowest contact angle (p < 0.05). Mean μSBS results (MPa) showed significant difference between the experimental groups (p = 0.011) and were in descending order as follows: DB (20 ± 8)^a?a b < C (12 ± 5)^b. Failure types were predominantly mixed failure type between the enamel and the resin cement with more than half of the resin remained on the enamel surface (32 to 33 out of 40) in all groups. Cohesive failure in the enamel was not observed in any of the groups. SEM analysis showed that AA group leaves abundant particles on the enamel surface and after DB and AA, etching could not remove the particles completely and expose the enamel prisms.