Effects of Proportions of Dietary Macronutrients on Glucocorticoid Metabolism in Diet-Induced Obesity in Rats

Tissue glucocorticoid levels in the liver and adipose tissue are regulated by regeneration of inactive glucocorticoid by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) and inactivation by 5α- and 5β-reductases. A low carbohydrate diet increases hepatic 11β-HSD1 and reduces glucocorticoid metabolism during weight loss in obese humans. We hypothesized that similar variations in macronutrient proportions regulate glucocorticoid metabolism in obese rats. Male Lister Hooded rats were fed an obesity-inducing ad libitum ‘Western’ diet (37% fat, n = 36) for 22 weeks, then randomised to continue this diet (n = 12) or to switch to either a low carbohydrate (n = 12) or a moderate carbohydrate (n = 12) diet for the final 8 weeks. A parallel lean control group were fed an ad libitum control diet (10% fat, n = 12) throughout. The low and moderate carbohydrate diets decreased hepatic 11β-HSD1 mRNA compared with the Western diet (both 0.7±0.0 vs 0.9±0.1 AU; p<0.01), but did not alter 11β-HSD1 in adipose tissue. 5α-Reductase mRNA was increased on the low carbohydrate compared with the moderate carbohydrate diet. Compared with lean controls, the Western diet decreased 11β-HSD1 activity (1.6±0.1 vs 2.8±0.1 nmol/mcg protein/hr; p<0.001) and increased 5α-reductase and 5β-reductase mRNAs (1.9±0.3 vs 1.0±0.2 and 1.6±0.1 vs 1.0±0.1 AU respectively; p<0.01) in the liver, and reduced 11β-HSD1 mRNA and activity (both p<0.01) in adipose tissue. Although an obesity-inducing high fat diet in rats recapitulates the abnormal glucocorticoid metabolism associated with human obesity in liver (but not in adipose tissue), a low carbohydrate diet does not increase hepatic 11β-HSD1 in obese rats as occurs in humans.     

Identification of a siderophore utilization locus in nontypeable <Emphasis Type="Italic">Haemophilus influenzae</Emphasis>

Background  

Haemophilus influenzae has an absolute aerobic growth requirement for either heme, or iron in the presence of protoporphyrin IX. Both iron and heme in the mammalian host are strictly limited in their availability to invading microorganisms. Many bacterial species overcome iron limitation in their environment by the synthesis and secretion of small iron binding molecules termed siderophores, which bind iron and deliver it into the bacterial cell via specific siderophore receptor proteins on the bacterial cell surface. There are currently no reports of siderophore production or utilization by H. influenzae.     

Form and functional morphology of Raetellops pulchella (Bivalvia: Mactridae): an example of convergent evolution with anomalodesmatans

Abstract. The bivalve Raetellops pulchella is a highly specialized, deposit-feeding member of the Mactridae. Studies of its form and function provide an example of how the bivalve body plan can be modified to facilitate the exploitation of mud as a food resource, and help in understanding how this lifestyle has evolved. Adaptations to this lifestyle include an overall reduction in ctenidial size and loss of the descending lamellae of both outer demibranchs. This reduction is associated with the enlargement of the labial palps to process inhaled sediment. In the mantle cavity, a waste canal below the posterior mantle flaps facilitates pseudofeces removal. The midgut is long and capacious, presumably to cope with the large amounts of ingested organic material. In addition, individuals of R. pulchella have unusually thin, brittle, and rostrate shells, with narrow siphonal gapes. They possess a shell buttress in each valve extending from the hinge plate to above the posterior adductor muscle. This buttress functions to prevent the brittle shell valves from fracturing when adduction occurs. A buttress is also seen in some representatives of the Anomalodesmata; in particular, the situation in R. pulchella is most like that seen in individuals of the similarly deposit-feeding species Offadesma angasi (Anomalodesmata: Periplomatidae). I interpret the similar shell form of these deposit-feeding clams as an example of convergent evolution.     

Assessing the welfare of genetically altered mice

In 2003, under the auspices of the main UK funders of biological and biomedical research, a working group was established with a remit to review potential welfare issues for genetically altered (GA) mice, to summarize current practice, and to recommend contemporary best practice for welfare assessments. The working group has produced a report which makes practical recommendations for GA mouse welfare assessment and dissemination of welfare information between establishments using a 'mouse passport'. The report can be found at www.nc3rs.org.uk/GAmice and www.lal.org.uk/gaa and includes templates for the recommended welfare assessment scheme and the mouse passport. An overview is provided below.     

Correspondence of low mean shear and high harmonic content in the porcine iliac arteries

BACKGROUND: Temporal variations in shear stress have been suggested to affect endothelial cell biology. To better quantify the range of dynamic shear forces that occur in vivo, the frequency content of shear variations that occur naturally over a cardiac cycle in the iliac arteries was determined. METHOD OF APPROACH: Computational fluid dynamic calculations were performed in six iliac arteries from three juvenile swine. Fourier analysis of the time-varying shear stress computed at the arterial wall was performed to determine the prevalence of shear forces occurring at higher frequencies in these arteries. RESULTS: While most of each artery experienced shear forces predominantly at the frequency of the heart rate, the frequency spectra at certain regions were dominated by shear forces at higher frequencies. Regions whose frequency spectra were dominated by higher harmonics generally experienced lower mean shear stress. The negative correlation between shear and dominant harmonic was significant (p=0.002). CONCLUSIONS: Since lesion development typically occurs in regions experiencing low time-average shear stress, this result suggests that the frequency content of the shear exposure may also be a contributing factor in lesion development. A better understanding of the vascular response to shear components of different frequencies might help rationalize the notion of "disturbed flow" as a hemodynamic entity.     

Increases in serum estrogen levels during major illness are caused by increased peripheral aromatization

Although serum testosterone levels decrease acutely in critically ill patients, estrogen levels rise. We hypothesized that increased rates of aromatization of androgens to estrogens underlie the increase in serum estrogen levels. Eleven men and three women (age 42-69 yr) were prospectively studied before and again after elective coronary artery bypass graft surgery (CABG). Each patient received priming doses of [(14)C]androgen and [(3)H]estrogen that were immediately followed by peripheral infusions for 210 min. Eight men and three women received androstenedione (A(4))/estrone (E(1)) and three men received testosterone (T)/estradiol (E(2)). Adipose tissue biopsies were obtained in another six men before and after CABG to evaluate levels of P450 aromatase mRNA. Serum T levels decreased postoperatively in all 17 men (P < 0.001), whereas E(1) levels rose (P = 0.004), with a trend toward a rise in E(2) (P = 0.23). Peripheral aromatization rates of androgens to estrogens rose markedly in all 14 patients (P < 0.0001). Estrogen clearance rates rose (P < 0.002). Mean serum A(4) levels increased slightly postoperatively (P = 0.04), although no increase in A(4) production rates (PRs) was observed. T PRs decreased in two of three men, whereas clearance rates increased in all three. Adipose tissue P450 aromatase mRNA content increased postoperatively (P < 0.001). We conclude that the primary cause of increased estrogen levels in acute illness is increased aromatase P450 gene expression, resulting in enhanced aromatization of androgens to estrogens, a previously undescribed endocrine response to acute illness. Both increased T clearance and decreased T production contribute to decreased serum T levels. Animal studies suggest that these opposing changes in circulating estrogen and androgen levels may be important to reduce morbidity and mortality in critical illness.     

Conformational analysis of methyl 5-O-methyl septanosides: effect of glycosylation on conformer populations

Methyl 5-O-methyl-alpha-d-glycero-d-idoseptanoside (3) and methyl 5-O-methyl-beta-d-glycero-d-guloseptanoside (4) were investigated as (1-->5)-linked di-/oligoseptanoside mimetics. Here we report the synthesis of 3 and 4 and describe their preferred solution conformations through a combination of ab initio/DFT calculations and (1)H (3)J(H,H) NMR coupling constant analysis. The conformations of 3 and 4 observed in this study are discussed in comparison to those of the parent (C5 hydroxy) compounds 1 and 2. The results indicate that methyl 5-O-methyl-alpha-septanoside 3 is relatively rigid and adopts the same (3,4)TC(5,6) conformation as 1. Methyl 5-O-methyl-beta-septanoside 4 is somewhat less rigid than its parent septanoside (2). In addition to the (6,O)TC(4,5) conformation adopted by 2, beta-septanoside 4 also populates the adjacent (3,4)TC(5,6) conformation. Glycosylation at C5 on beta-septanoside 4 therefore increases its overall flexibility and allows access to alternative ring conformations.     

High-performance liquid chromatography determination of alpha1-acid glycoprotein in small volumes of plasma from neonates

In order to investigate how the alpha1-acid glycoprotein (AGP) concentrations of neonates change in response to surgical stress, a simple high-performance liquid chromatography (HPLC)-assay for the measurement of alpha1-acid glycoprotein levels was developed. A fraction containing alpha1-acid glycoprotein was isolated from the bulk of plasma protein by addition of 0.6M perchloric acid and was then analysed directly on a short PLRP-S 4000A reversed phase column column. The method was validated by analysis of pooled plasma from healthy adults both in comparison with a calibration curve and by standard additions. The procedure was able to isolate alpha1-acid glycoprotein rapidly (<30 min) and required only 50 microl of plasma. The mean extraction recovery was 79.1% (CV 6.4%). The within-run precision for the analysis of three replicates of quality control sample ranged from +/-1.2 to +/-3.8% and the between-run precision was +/-6.1%. The method was linear (r(2)=0.988) over a concentration range from 6 to 100.0 mg/100 ml. The AGP levels in neonatal samples ranged from 25 to 93 mg/100 ml.     

Pyrazole CCK(1) receptor antagonists. Part 2: SAR studies by solid-phase library synthesis and determination of Free-Wilson additivity

High-throughput screening revealed compound 1 as a potent antagonist of the CCK(1) receptor. Here, we disclose the synthesis of combinatorial libraries by solid-phase synthesis on Kenner 'safety catch' resin. Additive QSAR models were used to determine a lack of consistent additive SAR within the matrix.     

Mutations in the embryonal subunit of the acetylcholine receptor (CHRNG) cause lethal and Escobar variants of multiple pterygium syndrome

Multiple pterygium syndromes (MPSs) comprise a group of multiple-congenital-anomaly disorders characterized by webbing (pterygia) of the neck, elbows, and/or knees and joint contractures (arthrogryposis). In addition, a variety of developmental defects (e.g., vertebral anomalies) may occur. MPSs are phenotypically and genetically heterogeneous but are traditionally divided into prenatally lethal and nonlethal (Escobar) types. To elucidate the pathogenesis of MPS, we undertook a genomewide linkage scan of a large consanguineous family and mapped a locus to 2q36-37. We then identified germline-inactivating mutations in the embryonal acetylcholine receptor gamma subunit (CHRNG) in families with both lethal and nonlethal MPSs. These findings extend the role of acetylcholine receptor dysfunction in human disease and provide new insights into the pathogenesis and management of fetal akinesia syndromes.