Rowett Research Institute

About: Rowett Research Institute is a based out in . It is known for research contribution in the topics: Rumen & Population. The organization has 2986 authors who have published 4459 publications receiving 239472 citations.

Circulating leptin in women: a longitudinal study in the menstrual cycle and during pregnancy

Abstract: OBJECTIVE To investigate whether leptin is linked to reproduction, circulating levels were measured longitudinally throughout spontaneous menstrual cycles and during pregnancy in normal women. DESIGN Longitudinal blood samples were collected from normal volunteers, either during regular menstrual cycles or during successful singleton pregnancies. PATIENTS Six healthy, regularly cycling, women volunteers (31.5 ± 3.0 years old, BMI = 21.6 + 0.5) were recruited for serial venous blood sampling throughout one complete menstrual cycle. In addition, five healthy, women (31.8 ± 1.2 years old, pre-pregnant BMI = 30.0 ± 3.1) provided serial venous blood samples throughout one complete singleton pregnancy. MEASUREMENTS Circulating venous oestradiol, progesterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), leptin and (pregnant group only) human chorionic gonadotrophin (hCG). RESULTS In spontaneously cycling women, changes in circulating leptin levels were associated with menstrual phase (P < 0.001) and correlated with progesterone levels (P < 0.05). Peak leptin concentrations were recorded during the luteal phase (P < 0.01), coincident with maximal progesterone levels (P < 0.05). Leptin concentrations were elevated throughout gestation (P < 0.05), and especially during the second trimester (P < 0.05). Post-partum, circulating leptin levels fell sharply to below pre-pregnant values. Leptin correlated with oestradiol (P < 0.05) and human chorionic gonadotrophin (hCG, P < 0.01) levels during pregnancy. First trimester (P < 0.05) and postpartum (P < 0.05) oestradiol concentrations and post-partum hCG levels exhibited the greatest correlation with circulating leptin. CONCLUSIONS We conclude that the relationship between body mass index and circulating leptin varies during the course of spontaneous cycles in women, the best correlation occurring during the luteal phase when progesterone and leptin concentrations are highest. This, together with the correlation between circulating oestradiol, hCG and leptin levels during pregnancy, strongly suggests a dynamic relationship between leptin and reproductive events in women.

Rates of rumen fermentation in relation to ammonia concentration

Abstract: 1. Four sheep were fed from automatic continuous feeders on whole barley fortified with graded levels of a urea solution. This approach was to a large extent successful in maintaining relatively steady states of rumen ammonia concentration. 2. Rates of barley fermentation in the rumen at various rumen NH3 concentrations were assessed by measuring the disappearance of barley dry matter from polyester bags suspended in the rumen of these sheep. 3. The minimal NH3 concentration for maximal rate of fermentation was estimated as 235 mg/l rumen fluid.

Metabolism of polyunsaturated fatty acids and their toxicity to the microflora of the rumen

Abstract: Ruminal microorganisms hydrogenate polyunsaturated fatty acids (PUFA) present in forages and thereby restrict the availability of health-promoting PUFA in meat and milk. The aim of this study was to investigate PUFA metabolism and the influence of PUFA on members of the ruminal microflora. Eleven of 26 predominant species of ruminal bacteria metabolised linoleic acid (LA; cis-9,cis-12–18:2) substantially. The most common product was vaccenic acid (trans-11–18:1), produced by species related to Butyrivibrio fibrisolvens. α-Linolenic acid (LNA; cis-9,cis-12,cis-15–18:3) was metabolised mostly by the same species. The fish oil fatty acids, eicosapentaenoic acid (EPA; 20:5(n − 3)) and docosahexaenoic acid (DHA; 22:6(n − 3)) were not metabolised. Cellulolytic bacteria did not grow in the presence of any PUFA at 50 μg ml−1, nor did some butyrate-producing bacteria, including the stearate producer Clostridium proteoclasticum, Butyrivibrio hungatei and Eubacterium ruminantium. Toxicity to growth was ranked EPA > DHA > LNA > LA. Cell integrity, as measured using propidium iodide, was damaged by LA in all 26 bacteria, but to different extents. Correlations between its effects on growth and apparent effects on cell integrity in different bacteria were low. Combined effects of LA and sodium lactate in E. ruminantium and C. proteoclasticum indicated that LA toxicity is linked to metabolism in butyrate-producing bacteria. PUFA also inhibited the growth of the cellulolytic ruminal fungi, with Neocallimastix frontalis producing small amounts of cis-9,trans-11–18:2 (CLA) from LA. Thus, while dietary PUFA might be useful in suppressing the numbers of biohydrogenating ruminal bacteria, particularly C. proteoclasticum, care should be taken to avoid unwanted effects in suppressing cellulolysis.

Induction, regulation, degradation, and biological significance of mammalian metallothioneins.

Abstract: MTs are small cysteine-rich metal-binding proteins found in many species and, although there are differences between them, it is of note that they have a great deal of sequence and structural homology. Mammalian MTs are 61 or 62 amino acid polypeptides containing 20 conserved cysteine residues that underpin the binding of metals. The existence of MT across species is indicative of its biological demand, while the conservation of cysteines indicates that these are undoubtedly central to the function of this protein. Four MT isoforms have been found so far, MT-1, MT-2, MT-3, and MT-4, but these also have subtypes with 17 MT genes identified in man, of which 10 are known to be functional. Different cells express different MT isoforms with varying levels of expression perhaps as a result of the different function of each isoform. Even different metals induce and bind to MTs to different extents. Over 40 years of research into MT have yielded much information on this protein, but have failed to assign to it a definitive biological role. The fact that multiple MT isoforms exist, and the great variety of substances and agents that act as inducers, further complicates the search for the biological role of MTs. This article reviews the current knowledge on the biochemistry, induction, regulation, and degradation of this protein in mammals, with a particular emphasis on human MTs. It also considers the possible biological roles of this protein, which include participation in cell proliferation and apoptosis, homeostasis of essential metals, cellular free radical scavenging, and metal detoxification.