Genetic analysis of indicators of cholesterol synthesis and absorption: lathosterol and phytosterols in Dutch twins and their parents.

Significant familial aggregation was observed for plasma levels of lathosterol (an indicator of whole-body cholesterol synthesis) and plant sterols campesterol and beta-sitosterol (indicators of cholesterol absorption) in 160 Dutch families consisting of adolescent mono- and dizygotic twin pairs and their parents. For lathosterol a moderate genetic heritability in parents and offspring (29%) was found. In addition, shared environment also contributed significantly (37%) to variation in plasma lathosterol concentrations in twin siblings. However, a model with different genetic heritabilities in the two generations (10% in parents and 68% in offspring) fitted the data almost as well. For plasma plant sterol concentrations high heritabilities were found. For campesterol heritability was 80% and for beta-sitosterol it was 73%, without evidence for differences in heritability between sexes or generations. No influence of common environmental influences shared by family members was seen for either campesterol or beta-sitosterol. Taken together, these results confirm and expand the hypothesis that individual differences in plasma levels of noncholesterol sterols are moderately (lathosterol) to highly (plant sterols) heritable.     

Effect of hand heating by a warm air box on O2 consumption of the contralateral arm.

Arterialization of venous blood is often used in studying forearm metabolism. Astrup et al. [Am. J. Physiol. 255 (Endocrinol. Metab. 18): E572-E578, 1988] showed that heating of the hand by a warming blanket caused a redistribution of blood flow in the contralateral arm and thus introduced errors in forearm skeletal muscle flux calculations. The present study was undertaken to investigate how hand heating by a warm air box (60 degrees C) would affect metabolism and blood flow in the contralateral arm before and during 3 h after a glucose load. Eleven healthy volunteers (5 males, 6 females) underwent an oral glucose tolerance test (70 g) on two different occasions, one test with and one without heating of the contralateral hand, in random order. Heating the hand for 30 min before glucose intake did not affect skin temperature, rectal temperature, deep venous oxygen saturation, forearm blood flow, or oxygen consumption of forearm skeletal muscle. Although, after the glucose load, heating significantly increased forearm blood flow (P less than 0.05), the integrated response after glucose was not significantly different between control and heating experiments [67 +/- 43 and 117 +/- 41 (SE) ml/100 ml tissue]. With both conditions, there was an increase in skin temperature (P less than 0.001, integrated response control: 369 +/- 79 and heating: 416 +/- 203 degrees C) and oxygen consumption of forearm muscle (control: 290 +/- 73, P less than 0.05 and heating: 390 +/- 130 mumol/100 ml, P less than 0.05) after glucose intake. These responses did not significantly differ between the conditions.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of the apolipoprotein E phenotype on plasma lipids is not influenced by environmental variability: results of a Dutch twin study

We tested the influence of the apolipoprotein E (apoE) polymorphism on the intrapair differences in the levels of plasma cholesterol, plasma triglycerides, low density lipoprotein-cholesterol, apoB and apoE in monozygotic (MZ) twins, and estimated whether or not there was a interaction between the apoE polymorphism and environmental factors. In 65 MZ twin pairs, the intrapair differences in the measured lipoprotein parameters were similar in the different apoE phenotype classes. This indicates that the effect of the apoE polymorphism is not influenced by environmental variability between the MZ pair members and accordingly identifies the APOE gene as a level gene.     

Molecular basis for the homophilic activated leukocyte cell adhesion molecule (ALCAM)-ALCAM interaction

Activated leukocyte cell adhesion molecule (ALCAM/CD166), a member of the immunoglobulin superfamily with five extracellular immunoglobulin-like domains, facilitates heterophilic (ALCAM-CD6) and homophilic (ALCAM-ALCAM) cell-cell interactions. While expressed in a wide variety of tissues and cells, ALCAM is restricted to subsets of cells usually involved in dynamic growth and/or migration processes. A structure-function analysis, using two monoclonal anti-ALCAM antibodies and a series of amino-terminally deleted ALCAM constructs, revealed that homophilic cell adhesion depended on ligand binding mediated by the membrane-distal amino-terminal immunoglobulin domain and on avidity controlled by ALCAM clustering at the cell surface involving membrane-proximal immunoglobulin domains. Co-expression of a transmembrane ALCAM deletion mutant, which lacks the ligand binding domain, and endogenous wild-type ALCAM inhibited homophilic cell-cell interactions by interference with ALCAM avidity, while homophilic, soluble ligand binding remained unaltered. The extracellular structures of ALCAM thus provide two structurally and functionally distinguishable modules, one involved in ligand binding and the other in avidity. Functionality of both modules is required for stable homophilic ALCAM-ALCAM cell-cell adhesion.     

Modifications of benzene myelotoxicity and metabolism by phenobarbital, SKF-525A and 3-methylcholanthrene

It has recently been suggested that the primary myelotoxic species generated from benzene is not produced directly from the parent compound, but from phenol or an even later metabolite (11). Several compounds that alter the activities of microsomal oxidative and conjugating enzymes were studied for their effects on benzene's myelotoxicity and metabolism. Phenobarbital (PB) protected animals from leucopenia and increased both to total amount of phenol as well as the amount of unconjugated phenol excreted in the urine. SKF-525A had no effect on the leucopenia, whereas it reduced the conversion of benzene to phenol without changing the excretion of unconjugated phenol. 3-Methylcholanthrene also did not prevent the leucopenia, but it did increase the conversion of benzene to phenol and the amount of unconjugated phenol excreted during the first days of the experiment. These data indicate that the early phases of benzene's metabolism may be modulated by the drug pretreatments employed, but myelotoxicity was abated only by PB. We conclude that the marrow effect of benzene is due to a metabolic product other than phenol and, furthermore that the formation of this toxic principle is not strictly dependent on the rate of phenol production.     

Effect of Variations in the Fatty Acid Chain of Oligofructose Fatty Acid Esters on Their Foaming Functionality

In this article the effect of variations in the fatty acid chain of oligofructose fatty acid esters (OFAE) on foamability and foam stability is described. First, oligofructose (OF) mono-esters containing saturated fatty acid chains ranging between C4 and C18 were studied. Additionally, a mono-ester containing a C16 mono-unsaturated fatty acid chain and a C12 di-ester were studied. Finally, to investigate the influence of the size of the hydrophilic group, commercially available sucrose esters were studied. The surface tension and surface rheological properties of air/water interfaces stabilized by the esters were determined, as well as the foaming properties of the esters, at a bulk concentration of 0.2 % (w/v). OF mono-esters with intermediate fatty acid chain lengths (C10-C16) were able to migrate quickly to the interface producing foams with small bubbles (0.4 mm), a relatively narrow bubble size distribution, and a high stability. For oligofructose mono-esters containing fatty acids C4 and C8, the bulk concentration of 0.2 % (w/v) was below the CMC, resulting in insufficient surface coverage, and low foamability and foam stability. The OF C18 mono-ester and the OF C12 di-ester were slow to migrate to the interface resulting in low foamability. Despite similar surface tension values, the foam half-life time of OFAE was higher than of the corresponding sucrose esters. OFAE gave higher surface dilatational moduli compared to sucrose esters. Based on the frequency dependence of the modulus and analysis of Lissajous plots, we propose that OFAE may be forming a soft glass at the interface.     

SoilGrids1km — Global Soil Information Based on Automated Mapping

BackgroundSoils are widely recognized as a non-renewable natural resource and as biophysical carbon sinks. As such, there is a growing requirement for global soil information. Although several global soil information systems already exist, these tend to suffer from inconsistencies and limited spatial detail.Conclusions/SignificanceSoilGrids1km provide an initial set of examples of soil spatial data for input into global models at a resolution and consistency not previously available. Some of the main limitations of the current version of SoilGrids1km are: (1) weak relationships between soil properties/classes and explanatory variables due to scale mismatches, (2) difficulty to obtain covariates that capture soil forming factors, (3) low sampling density and spatial clustering of soil profile locations. However, as the SoilGrids system is highly automated and flexible, increasingly accurate predictions can be generated as new input data become available. SoilGrids1km are available for download via http://soilgrids.org under a Creative Commons Non Commercial license.