Effect of Maternal Diet on Maternal Milk and Breastfed Infant Gut Microbiomes: A Scoping Review

While it is widely recognized that nutrition during pregnancy and lactation can affect the microbiome of breast milk as well as the formation of the infant gut microbiome, we are only just beginning to understand the extent to which maternal diet impacts these microbiomes. Given the importance of the microbiome for infant health, we conducted a comprehensive review of the published literature to explore the current scope of knowledge regarding associations between maternal diet and the breast milk and infant gut microbiomes. Papers included in this review assessed either diet during lactation or pregnancy, and the milk and/or infant gut microbiome. Sources included cohort studies, randomized clinical trials, one case-control study, and one crossover study. From an initial review of 808 abstracts, we identified 19 reports for a full analysis. Only two studies assessed the effects of maternal diet on both milk and infant microbiomes. Although the reviewed literature supports the importance of a varied, nutrient-dense maternal diet in the formation of the infant’s gut microbiome, several studies found factors other than maternal diet to have a greater impact on the infant microbiome

Hypoxia promotes production of neural crest cells in the embryonic head

ABSTRACT Hypoxia is encountered in either pathological or physiological conditions, the latter of which is seen in amniote embryos prior to the commencement of a functional blood circulation. During the hypoxic stage, a large number of neural crest cells arise from the head neural tube by epithelial-to-mesenchymal transition (EMT). As EMT-like cancer dissemination can be promoted by hypoxia, we investigated whether hypoxia contributes to embryonic EMT. Using chick embryos, we show that the hypoxic cellular response, mediated by hypoxia-inducible factor (HIF)-1α, is required to produce a sufficient number of neural crest cells. Among the genes that are involved in neural crest cell development, some genes are more sensitive to hypoxia than others, demonstrating that the effect of hypoxia is gene specific. Once blood circulation becomes fully functional, the embryonic head no longer produces neural crest cells in vivo, despite the capability to do so in a hypoxia-mimicking condition in vitro, suggesting that the oxygen supply helps to stop emigration of neural crest cells in the head. These results highlight the importance of hypoxia in normal embryonic development.</jats:p

Arachidonic acid actions on functional integrity and attenuation of the negative effects of palmitic acid in a clonal pancreatic β-cell line

Chronic exposure of pancreatic β-cells to saturated non-esterified fatty acids can lead to inhibition of insulin secretion and apoptosis. Several previous studies have demonstrated that saturated fatty acids such as PA (palmitic acid) are detrimental to β-cell function compared with unsaturated fatty acids. In the present study, we describe the effect of the polyunsaturated AA (arachidonic acid) on the function of the clonal pancreatic β-cell line BRIN-BD11 and demonstrate AA-dependent attenuation of PA effects. When added to β-cell incubations at 100 μM, AA can stimulate cell proliferation and chronic (24 h) basal insulin secretion. Microarray analysis and/or real-time PCR indicated significant AA-dependent up-regulation of genes involved in proliferation and fatty acid metabolism [e.g. Angptl (angiopoietin-like protein 4), Ech1 (peroxisomal Δ3,5,Δ2,4-dienoyl-CoA isomerase), Cox-1 (cyclo-oxygenase-1) and Cox-2, P<0.05]. Experiments using specific COX and LOX (lipoxygenase) inhibitors demonstrated the importance of COX-1 activity for acute (20 min) stimulation of insulin secretion, suggesting that AA metabolites may be responsible for the insulinotropic effects. Moreover, concomitant incubation of AA with PA dose-dependently attenuated the detrimental effects of the saturated fatty acid, so reducing apoptosis and decreasing parameters of oxidative stress [ROS (reactive oxygen species) and NO levels] while improving the GSH/GSSG ratio. AA decreased the protein expression of iNOS (inducible NO synthase), the p65 subunit of NF-κB (nuclear factor κB) and the p47 subunit of NADPH oxidase in PA-treated cells. These findings indicate that AA has an important regulatory and protective β-cell action, which may be beneficial to function and survival in the ‘lipotoxic’ environment commonly associated with Type 2 diabetes mellitus

2015 ESC Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death the Task Force for the Management of Patients with Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death of the European Society of Cardiology (ESC) Endorsed by: Association for European Paediatric and Congenital Cardiology (AEPC)

N/

Bi-allelic Loss-of-Function CACNA1B Mutations in Progressive Epilepsy-Dyskinesia.

The occurrence of non-epileptic hyperkinetic movements in the context of developmental epileptic encephalopathies is an increasingly recognized phenomenon. Identification of causative mutations provides an important insight into common pathogenic mechanisms that cause both seizures and abnormal motor control. We report bi-allelic loss-of-function CACNA1B variants in six children from three unrelated families whose affected members present with a complex and progressive neurological syndrome. All affected individuals presented with epileptic encephalopathy, severe neurodevelopmental delay (often with regression), and a hyperkinetic movement disorder. Additional neurological features included postnatal microcephaly and hypotonia. Five children died in childhood or adolescence (mean age of death: 9 years), mainly as a result of secondary respiratory complications. CACNA1B encodes the pore-forming subunit of the pre-synaptic neuronal voltage-gated calcium channel Cav2.2/N-type, crucial for SNARE-mediated neurotransmission, particularly in the early postnatal period. Bi-allelic loss-of-function variants in CACNA1B are predicted to cause disruption of Ca2+ influx, leading to impaired synaptic neurotransmission. The resultant effect on neuronal function is likely to be important in the development of involuntary movements and epilepsy. Overall, our findings provide further evidence for the key role of Cav2.2 in normal human neurodevelopment.MAK is funded by an NIHR Research Professorship and receives funding from the Wellcome Trust, Great Ormond Street Children's Hospital Charity, and Rosetrees Trust. E.M. received funding from the Rosetrees Trust (CD-A53) and Great Ormond Street Hospital Children's Charity. K.G. received funding from Temple Street Foundation. A.M. is funded by Great Ormond Street Hospital, the National Institute for Health Research (NIHR), and Biomedical Research Centre. F.L.R. and D.G. are funded by Cambridge Biomedical Research Centre. K.C. and A.S.J. are funded by NIHR Bioresource for Rare Diseases. The DDD Study presents independent research commissioned by the Health Innovation Challenge Fund (grant number HICF-1009-003), a parallel funding partnership between the Wellcome Trust and the Department of Health, and the Wellcome Trust Sanger Institute (grant number WT098051). We acknowledge support from the UK Department of Health via the NIHR comprehensive Biomedical Research Centre award to Guy's and St. Thomas' National Health Service (NHS) Foundation Trust in partnership with King's College London. This research was also supported by the NIHR Great Ormond Street Hospital Biomedical Research Centre. J.H.C. is in receipt of an NIHR Senior Investigator Award. The research team acknowledges the support of the NIHR through the Comprehensive Clinical Research Network. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR, Department of Health, or Wellcome Trust. E.R.M. acknowledges support from NIHR Cambridge Biomedical Research Centre, an NIHR Senior Investigator Award, and the University of Cambridge has received salary support in respect of E.R.M. from the NHS in the East of England through the Clinical Academic Reserve. I.E.S. is supported by the National Health and Medical Research Council of Australia (Program Grant and Practitioner Fellowship)

Adding 6 months of androgen deprivation therapy to postoperative radiotherapy for prostate cancer: a comparison of short-course versus no androgen deprivation therapy in the RADICALS-HD randomised controlled trial

Background Previous evidence indicates that adjuvant, short-course androgen deprivation therapy (ADT) improves metastasis-free survival when given with primary radiotherapy for intermediate-risk and high-risk localised prostate cancer. However, the value of ADT with postoperative radiotherapy after radical prostatectomy is unclear. Methods RADICALS-HD was an international randomised controlled trial to test the efficacy of ADT used in combination with postoperative radiotherapy for prostate cancer. Key eligibility criteria were indication for radiotherapy after radical prostatectomy for prostate cancer, prostate-specific antigen less than 5 ng/mL, absence of metastatic disease, and written consent. Participants were randomly assigned (1:1) to radiotherapy alone (no ADT) or radiotherapy with 6 months of ADT (short-course ADT), using monthly subcutaneous gonadotropin-releasing hormone analogue injections, daily oral bicalutamide monotherapy 150 mg, or monthly subcutaneous degarelix. Randomisation was done centrally through minimisation with a random element, stratified by Gleason score, positive margins, radiotherapy timing, planned radiotherapy schedule, and planned type of ADT, in a computerised system. The allocated treatment was not masked. The primary outcome measure was metastasis-free survival, defined as distant metastasis arising from prostate cancer or death from any cause. Standard survival analysis methods were used, accounting for randomisation stratification factors. The trial had 80% power with two-sided α of 5% to detect an absolute increase in 10-year metastasis-free survival from 80% to 86% (hazard ratio [HR] 0·67). Analyses followed the intention-to-treat principle. The trial is registered with the ISRCTN registry, ISRCTN40814031, and ClinicalTrials.gov, NCT00541047. Findings Between Nov 22, 2007, and June 29, 2015, 1480 patients (median age 66 years [IQR 61–69]) were randomly assigned to receive no ADT (n=737) or short-course ADT (n=743) in addition to postoperative radiotherapy at 121 centres in Canada, Denmark, Ireland, and the UK. With a median follow-up of 9·0 years (IQR 7·1–10·1), metastasis-free survival events were reported for 268 participants (142 in the no ADT group and 126 in the short-course ADT group; HR 0·886 [95% CI 0·688–1·140], p=0·35). 10-year metastasis-free survival was 79·2% (95% CI 75·4–82·5) in the no ADT group and 80·4% (76·6–83·6) in the short-course ADT group. Toxicity of grade 3 or higher was reported for 121 (17%) of 737 participants in the no ADT group and 100 (14%) of 743 in the short-course ADT group (p=0·15), with no treatment-related deaths. Interpretation Metastatic disease is uncommon following postoperative bed radiotherapy after radical prostatectomy. Adding 6 months of ADT to this radiotherapy did not improve metastasis-free survival compared with no ADT. These findings do not support the use of short-course ADT with postoperative radiotherapy in this patient population

Duration of androgen deprivation therapy with postoperative radiotherapy for prostate cancer: a comparison of long-course versus short-course androgen deprivation therapy in the RADICALS-HD randomised trial

Background Previous evidence supports androgen deprivation therapy (ADT) with primary radiotherapy as initial treatment for intermediate-risk and high-risk localised prostate cancer. However, the use and optimal duration of ADT with postoperative radiotherapy after radical prostatectomy remains uncertain. Methods RADICALS-HD was a randomised controlled trial of ADT duration within the RADICALS protocol. Here, we report on the comparison of short-course versus long-course ADT. Key eligibility criteria were indication for radiotherapy after previous radical prostatectomy for prostate cancer, prostate-specific antigen less than 5 ng/mL, absence of metastatic disease, and written consent. Participants were randomly assigned (1:1) to add 6 months of ADT (short-course ADT) or 24 months of ADT (long-course ADT) to radiotherapy, using subcutaneous gonadotrophin-releasing hormone analogue (monthly in the short-course ADT group and 3-monthly in the long-course ADT group), daily oral bicalutamide monotherapy 150 mg, or monthly subcutaneous degarelix. Randomisation was done centrally through minimisation with a random element, stratified by Gleason score, positive margins, radiotherapy timing, planned radiotherapy schedule, and planned type of ADT, in a computerised system. The allocated treatment was not masked. The primary outcome measure was metastasis-free survival, defined as metastasis arising from prostate cancer or death from any cause. The comparison had more than 80% power with two-sided α of 5% to detect an absolute increase in 10-year metastasis-free survival from 75% to 81% (hazard ratio [HR] 0·72). Standard time-to-event analyses were used. Analyses followed intention-to-treat principle. The trial is registered with the ISRCTN registry, ISRCTN40814031, and ClinicalTrials.gov , NCT00541047 . Findings Between Jan 30, 2008, and July 7, 2015, 1523 patients (median age 65 years, IQR 60–69) were randomly assigned to receive short-course ADT (n=761) or long-course ADT (n=762) in addition to postoperative radiotherapy at 138 centres in Canada, Denmark, Ireland, and the UK. With a median follow-up of 8·9 years (7·0–10·0), 313 metastasis-free survival events were reported overall (174 in the short-course ADT group and 139 in the long-course ADT group; HR 0·773 [95% CI 0·612–0·975]; p=0·029). 10-year metastasis-free survival was 71·9% (95% CI 67·6–75·7) in the short-course ADT group and 78·1% (74·2–81·5) in the long-course ADT group. Toxicity of grade 3 or higher was reported for 105 (14%) of 753 participants in the short-course ADT group and 142 (19%) of 757 participants in the long-course ADT group (p=0·025), with no treatment-related deaths. Interpretation Compared with adding 6 months of ADT, adding 24 months of ADT improved metastasis-free survival in people receiving postoperative radiotherapy. For individuals who can accept the additional duration of adverse effects, long-course ADT should be offered with postoperative radiotherapy. Funding Cancer Research UK, UK Research and Innovation (formerly Medical Research Council), and Canadian Cancer Society

Mammalian acetate metabolism

This work is a study of sense aspects of the metabolism of free acetic acid in non-ruminant mammals. The metabolic significance of acetate is recognized in the ruminant and in certain micro-organisms where large amounts of acetate are utilized. The lack of a sufficiently sensitive method for acetate determination coupled with the low concentrations present in the tissues of non-ruminants has been a major impediment to studies on acetate metabolism in these animals in the past. A method suitable for acetate determination in the tissues of non-ruminants has been developed. The study has been pursued by measurements of acetate in blood and tissues of the rat, and by investigating acetate production in in vitro preparations of rat liver and comparing it with that of ketone bodies. Chapter 1. Introduction. The reasons for undertaking this study are described. the presence of small amounts of acetate in animal tissues and its ready utilization by selective tissues suggest that acetate may have a role as a respiratory fuel analogous to that discussed by Krebs (1961a) for the ketone bodies. The pathways of metabolism of acetate and the acetyl group are briefly outlined; and the possible precursors of free acetate and the likely sites of its formation in the body are described. Chapter 2. Development of a method for the measurement of acetic acid. Many Methods of acetate determination used by earlier workers have been investigated. Microdiffusion, (Serlin and Cotzias, 1955), even with various modifications, has not been found to be sufficiently sensitive for the present purpose; lactate and bicarbonate have been found to cause considerable interference in a micro-distillation method (Bartley, 1953). An attempt was made to obtain an active preparation of acetokinase (E. Coli), but since the Km value of the enzyme is so high (0.3 M acetate, Rose, Grunberg-Manago, Korey and Ochoa, 1954), the amounts of enzyme required to measure low concentrations of acetate would be relatively large, so enzymic assays were not pursued. Finally, a gas chromatographic method (Baumgardt, 1964) has been adapted. This system can take aqueous samples thus cutting out the need for cumbersome extraction procedures. However, the samples must first be purified by steam-distillation (Dr. E.F. Annison, personal communication). Isovalerate is used as a marker. The method is specific for acetic acid. The mean recovery of 1 - 10 μmoles of acetate added to blood, perfusion medium or tissue homogenate is between 93% and 105%, while the individual errors are &pm; 29% at worst. Amounts of acetate of 0.08 μmole and upwards can be determined. Chapter 3. Acetate in rat blood and its origin. The acetate level in rat blood, collected by cannulation of the aorta , remains at approximately 0.4 mM regardless of dietary alterations (feeding , fasting for 24 or 48 hr., high-roughage diet), but blood from the portal vein which drains i.e. the caecum. contains 4 times as much acetate, and small amounts of other volatile fatty acids, notably propionate. This difference in concentration in the blood from different parts of the body points to (i) an Intestinal origin of acetate, and (ii) uptake of acetate from the blood by the liver and possibly the heart. The caecum contents contain relatively large amounts of volatile fatty acids (approximately 50 μmoles/g.) of which about 50% is acetate. The volatile fatty acid composition is similar to that of sheep rumen contents (Annison, 1954b), although on a smaller scale. The concentration of acetate in caecum contents is only half that in the rumen, and relative to body weight, the rat caecum is only about 1% while the sheep rumen is approximately 10 - 20% (from Annison and Lewis. 1959; Bergman, Reid, Murray, Brockway and Whitelaw. 1965). Oral treatment of the rats with neomycin, an antibiotic, to reduce the bacterial activity of the gut to a minimum, decreases the acetate in the caecum contents to one-fifth and in the portal blood to one-third of their normal concentrations, the acetate in portal blood now being within the range found in aortic blood. It is concluded that acetate in rat blood arises at least partly by bacterial activity in the Intestine. and especially within the caecum. A calculation based on the arterio-portal venous difference for acetate and on an approximation of portal blood flow rate (from Dobson and Jones , 1952) show that the acetate absorbed daily from the intestine, if completely oxidised, could account maximally for 10% of the basal caloric output in the rat , as compared with a corresponding value of 42% in the ruminant (Bergman et al. 1965). Chapter 4. Acetate in the tissues of normal and alloxan-diabetic rats. The tissue levels of acetate are comparable with those found by an enzymic assay (Bergmeyer and Moellering , 1966), and are highest in liver at about 0.4 μmole/g. fr. wt., intermediate in kidney, and lowest in heart muscle which readily utilizes acetate (Wllliamson, 1962). Acute alloxan-diabetes causes the level to rise by 150% in liver and by 50% in kidney, while the concentration in blood and in heart muscle remain unchanged. Fasting (48 hr.) or bran- feeding have no effect on liver acetate level. The factors which generate and dispose of from acetate are discussed , but the control of its level is not sufficiently understood to offer a satisfactory explanation for the altered levels in diabetes. Chapter 5. Acetate and ketone body production by rat liver in vitro. Preliminary experiments have shown that acatate is produced by rat liver slices, at a rate coaparable to that of ketone body formation, and that it is increased by the addition of fatty acids. In the perfused liver much higher rates of production of both acatate and ketone bodies are observed; the maximal endogenous rates are 45 μmole. acetate/g. fr. wt./hr., and 42 μmoles total katone bodies/g. fr. wt./hr. (in the livers of 48 hr. fasted rats). This preparation is adopted for further investigation of the effects of dietary alterations and of the addition of various precursors of the acetyl group (fatty acids, pyruvate and ethanol)> The initial rate of acetate formation is constant, but it starts to decline more rapidly in the livers of fed rats (after 30-60 min.) than in those of 48 hr. fasted rats (after 60-90 min.). Ketogenesis is minimal when donor rats are fed and is markedly and progressively increased when the rats are fasted for 24 and 48 hr. Addition of fatty acids with or without carnitine has no affect on acatate production, but greatly enhances that of katone bodies. It is calculated from net metabolic changes, that 2 mM butyrate is quantitatively converted, and 0.5 mM oleate is 60% converted to ketone bodies. The fate of the remaining oleate has not been determined. It is probably partly converted to CO2 and partly utilized by the biosynthetic reactions of acetyl CoA. Added ethanol and pyruvate are strongly anti-ketogenic, and do not alter acetate formation when the donor rats are fasted. Whan the rats are fed, acetate production is enhanced by 5 mM ethanol (2 perfusions), probably related to the higher activities of liver alcohol and aldehyde dehydrogenases (EC 1.1.1.1., EC 1.2.1.3.) in that state (Büttner, 1965). Such large-scale acetate production by rat liver preparations was not previously observed (Hochheuser, Weiss and Wieland, 1964; Hepp, Prüsse, Weiss and Wieland, 1966a,b). The evidence for the metabolic origin of the acetate appearing in the perfusion medium is summarised, and the likely endogenous precursors of this acetate are discussed. Chapter 6. Additional comments. On the basis of the present findings some possible approaches to the further study of acetate metabolism in the rat are suggested; and a modification to the method of acetate determination is tentatively proposed

Mammalian acetate metabolism

This work is a study of sense aspects of the metabolism of free acetic acid in non-ruminant mammals. The metabolic significance of acetate is recognized in the ruminant and in certain micro-organisms where large amounts of acetate are utilized. The lack of a sufficiently sensitive method for acetate determination coupled with the low concentrations present in the tissues of non-ruminants has been a major impediment to studies on acetate metabolism in these animals in the past. A method suitable for acetate determination in the tissues of non-ruminants has been developed. The study has been pursued by measurements of acetate in blood and tissues of the rat, and by investigating acetate production in in vitro preparations of rat liver and comparing it with that of ketone bodies. Chapter 1. Introduction. The reasons for undertaking this study are described. the presence of small amounts of acetate in animal tissues and its ready utilization by selective tissues suggest that acetate may have a role as a respiratory fuel analogous to that discussed by Krebs (1961a) for the ketone bodies. The pathways of metabolism of acetate and the acetyl group are briefly outlined; and the possible precursors of free acetate and the likely sites of its formation in the body are described. Chapter 2. Development of a method for the measurement of acetic acid. Many Methods of acetate determination used by earlier workers have been investigated. Microdiffusion, (Serlin and Cotzias, 1955), even with various modifications, has not been found to be sufficiently sensitive for the present purpose; lactate and bicarbonate have been found to cause considerable interference in a micro-distillation method (Bartley, 1953). An attempt was made to obtain an active preparation of acetokinase (E. Coli), but since the Km value of the enzyme is so high (0.3 M acetate, Rose, Grunberg-Manago, Korey and Ochoa, 1954), the amounts of enzyme required to measure low concentrations of acetate would be relatively large, so enzymic assays were not pursued. Finally, a gas chromatographic method (Baumgardt, 1964) has been adapted. This system can take aqueous samples thus cutting out the need for cumbersome extraction procedures. However, the samples must first be purified by steam-distillation (Dr. E.F. Annison, personal communication). Isovalerate is used as a marker. The method is specific for acetic acid. The mean recovery of 1 - 10 μmoles of acetate added to blood, perfusion medium or tissue homogenate is between 93% and 105%, while the individual errors are &amp;pm; 29% at worst. Amounts of acetate of 0.08 μmole and upwards can be determined. Chapter 3. Acetate in rat blood and its origin. The acetate level in rat blood, collected by cannulation of the aorta , remains at approximately 0.4 mM regardless of dietary alterations (feeding , fasting for 24 or 48 hr., high-roughage diet), but blood from the portal vein which drains i.e. the caecum. contains 4 times as much acetate, and small amounts of other volatile fatty acids, notably propionate. This difference in concentration in the blood from different parts of the body points to (i) an Intestinal origin of acetate, and (ii) uptake of acetate from the blood by the liver and possibly the heart. The caecum contents contain relatively large amounts of volatile fatty acids (approximately 50 μmoles/g.) of which about 50% is acetate. The volatile fatty acid composition is similar to that of sheep rumen contents (Annison, 1954b), although on a smaller scale. The concentration of acetate in caecum contents is only half that in the rumen, and relative to body weight, the rat caecum is only about 1% while the sheep rumen is approximately 10 - 20% (from Annison and Lewis. 1959; Bergman, Reid, Murray, Brockway and Whitelaw. 1965). Oral treatment of the rats with neomycin, an antibiotic, to reduce the bacterial activity of the gut to a minimum, decreases the acetate in the caecum contents to one-fifth and in the portal blood to one-third of their normal concentrations, the acetate in portal blood now being within the range found in aortic blood. It is concluded that acetate in rat blood arises at least partly by bacterial activity in the Intestine. and especially within the caecum. A calculation based on the arterio-portal venous difference for acetate and on an approximation of portal blood flow rate (from Dobson and Jones , 1952) show that the acetate absorbed daily from the intestine, if completely oxidised, could account maximally for 10% of the basal caloric output in the rat , as compared with a corresponding value of 42% in the ruminant (Bergman et al. 1965). Chapter 4. Acetate in the tissues of normal and alloxan-diabetic rats. The tissue levels of acetate are comparable with those found by an enzymic assay (Bergmeyer and Moellering , 1966), and are highest in liver at about 0.4 μmole/g. fr. wt., intermediate in kidney, and lowest in heart muscle which readily utilizes acetate (Wllliamson, 1962). Acute alloxan-diabetes causes the level to rise by 150% in liver and by 50% in kidney, while the concentration in blood and in heart muscle remain unchanged. Fasting (48 hr.) or bran- feeding have no effect on liver acetate level. The factors which generate and dispose of from acetate are discussed , but the control of its level is not sufficiently understood to offer a satisfactory explanation for the altered levels in diabetes. Chapter 5. Acetate and ketone body production by rat liver in vitro. Preliminary experiments have shown that acatate is produced by rat liver slices, at a rate coaparable to that of ketone body formation, and that it is increased by the addition of fatty acids. In the perfused liver much higher rates of production of both acatate and ketone bodies are observed; the maximal endogenous rates are 45 μmole. acetate/g. fr. wt./hr., and 42 μmoles total katone bodies/g. fr. wt./hr. (in the livers of 48 hr. fasted rats). This preparation is adopted for further investigation of the effects of dietary alterations and of the addition of various precursors of the acetyl group (fatty acids, pyruvate and ethanol)&gt; The initial rate of acetate formation is constant, but it starts to decline more rapidly in the livers of fed rats (after 30-60 min.) than in those of 48 hr. fasted rats (after 60-90 min.). Ketogenesis is minimal when donor rats are fed and is markedly and progressively increased when the rats are fasted for 24 and 48 hr. Addition of fatty acids with or without carnitine has no affect on acatate production, but greatly enhances that of katone bodies. It is calculated from net metabolic changes, that 2 mM butyrate is quantitatively converted, and 0.5 mM oleate is 60% converted to ketone bodies. The fate of the remaining oleate has not been determined. It is probably partly converted to CO2 and partly utilized by the biosynthetic reactions of acetyl CoA. Added ethanol and pyruvate are strongly anti-ketogenic, and do not alter acetate formation when the donor rats are fasted. Whan the rats are fed, acetate production is enhanced by 5 mM ethanol (2 perfusions), probably related to the higher activities of liver alcohol and aldehyde dehydrogenases (EC 1.1.1.1., EC 1.2.1.3.) in that state (Büttner, 1965). Such large-scale acetate production by rat liver preparations was not previously observed (Hochheuser, Weiss and Wieland, 1964; Hepp, Prüsse, Weiss and Wieland, 1966a,b). The evidence for the metabolic origin of the acetate appearing in the perfusion medium is summarised, and the likely endogenous precursors of this acetate are discussed. Chapter 6. Additional comments. On the basis of the present findings some possible approaches to the further study of acetate metabolism in the rat are suggested; and a modification to the method of acetate determination is tentatively proposed.</p

Molecular Mechanisms of Glucolipotoxicity in Diabetes Saturated and unsaturated (including arachidonic acid) non-esterified fatty acid modulation of insulin secretion from pancreatic β-cells

Abstract Both stimulatory and detrimental effects of NEFAs (non-esterified fatty acids) on pancreatic β-cells have been recognized. Acute exposure of the pancreatic β-cell to high glucose concentrations and/or saturated NEFAs results in a substantial increase in insulin release, whereas chronic exposure results in desensitization and suppression of secretion followed by induction of apoptosis. Some unsaturated NEFAs also promote insulin release acutely, but they are less toxic to β-cells during chronic exposure and can even exert positive protective effects. In the present review, we focus on exogenous and endogenous effects of NEFAs, including the polyunsaturated fatty acid, arachidonic acid (or its metabolites generated from cyclo-oxygenase activity), on β-cell metabolism, and have explored the outcomes with respect to β-cell insulin secretion. Utilization of β-cell lines for assessment of β-cell function In writing the present review, we are fully aware that most of the studies cited have utilized rat-, mouse-or hamster-derived primary islet cells or insulinoma β-cell lines to study function in vitro. This is due to the inherent difficulty in maintaining primary rodent islet β-cell mass and function for more than a few days in vitro and of course the scarcity of human islets for research purposes. There are as yet no suitable human β-cell lines available for unrestricted in vitro studies. However, the major rodent β-cell lines have provided substantial data and insights into cell function in normal or pathogenic situations. The most widely used cell lines include INS-1, MIN-6, RINm5F and BRIN BD11. Modulation of insulin secretion by NEFAs (non-esterified fatty acid) In vivo studies Insulin secretion is influenced, at any given time, predominately by the blood glucose concentration and by the prevailing fatty acids in the circulatio