We recorded arterial pressure (BP) and heart rate (HR) in type-1 diabetic rats versus controls for ≥ 6 months. Diabetic rats (DIAB) were maintained on insulin from the day glucose > 250 mg/dl (“Day 0”). Weight was similar between groups until ~3 weeks before Day 0 when the weight in DIAB transiently lagged the controls (CONT); this difference was maintained throughout the study, but both groups otherwise gained weight in parallel. Plasma glucose attained 371 ± 109 (SD) mg/dl by day 1 in DIAB. Mean BP was similar across groups, and declined through the initial 4–6 months in both the CONT (at −0.06 ± 0.04 mm Hg/day) and in the DIAB (at −0.14 ± 0.21 mm Hg/day; NS vs. CONT). HR in the CONT (Month 1: 341 ± 13 bpm) exceeded DIAB (325 ± 25 bpm) through ~6 months after Day 0, and also decreased progressively over this period in CONT (−0.19 ± 0.14 beats/day) and DIAB (−0.29 ± 0.23 bpm/day; NS vs. CONT) before leveling. The BP power within 0.35–0.45 Hz changed during the 90 minutes before vs. after the transition from dark to light, and light to dark; there were no between group differences. The slope of the log-log linear portion of the BP power spectrum between 1.0/hr to 1/min was similar across groups, and increased in both from month 1 to month 6. Regulatory mechanisms maintain similar profiles in BP and HR in diabetic vs. control animals through the initial half year of the disease.
Cardiovascular system; autonomic nervous system; weight gain; plasma glucose; dysautonomia; slope β (beta)
Quantitative tractography may provide insights into regional heterogeneity of changes in white matter structure in normal ageing. Here we examine how brain atrophy and white matter lesions affect correlations between tract shape, tract integrity and age in a range of frontal and non-frontal tracts in 90 non-demented subjects aged over 65 years using an enhanced version of probabilistic neighbourhood tractography. This novel method for automatic single seed point placement employs unsupervised learning and streamline selection to provide reliable and accurate tract segmentation, whilst also indicating how the shape of an individual tract compares to that of a predefined reference tract. There were significant negative correlations between tract shape similarity to reference tracts derived from a young brain white matter atlas and age in genu and splenium of corpus callosum. Controlling for intracranial and lateral ventricle volume, the latter of which increased significantly with age, attenuated these correlations by 40 and 84 % respectively, indicating that this age-related change in callosal tract topology is significantly mediated by global atrophy and ventricular enlargement. In accordance with the ‘frontal ageing’ hypothesis, there was a significant positive correlation between mean diffusivity (〈D〉) and age, and a significant negative correlation between fractional anisotropy (FA) and age in corpus callosum genu; correlations not seen in splenium. Significant positive correlations were also observed between 〈D〉 and age in bilateral cingulum cingulate gyri, uncinate fasciculi and right corticospinal tract. This pattern of correlations was not, however, reproduced when those subjects with significant white matter lesion load were analyzed separately from those without. These data therefore suggest that brain atrophy and white matter lesions play a significant role in driving regional patterns of age-related changes in white matter tract shape and integrity.
Ageing; white matter; magnetic resonance imaging; water diffusion tensor; tractography
A common human gut bacterium, Bacteroides fragilis, produces a sphingolipid ligand for the conserved host receptor CD1d and can modulate natural killer T cell activity.
While the human gut microbiota are suspected to produce diffusible small molecules that modulate host signaling pathways, few of these molecules have been identified. Species of Bacteroides and their relatives, which often comprise >50% of the gut community, are unusual among bacteria in that their membrane is rich in sphingolipids, a class of signaling molecules that play a key role in inducing apoptosis and modulating the host immune response. Although known for more than three decades, the full repertoire of Bacteroides sphingolipids has not been defined. Here, we use a combination of genetics and chemistry to identify the sphingolipids produced by Bacteroides fragilis NCTC 9343. We constructed a deletion mutant of BF2461, a putative serine palmitoyltransferase whose yeast homolog catalyzes the committed step in sphingolipid biosynthesis. We show that the Δ2461 mutant is sphingolipid deficient, enabling us to purify and solve the structures of three alkaline-stable lipids present in the wild-type strain but absent from the mutant. The first compound was the known sphingolipid ceramide phosphorylethanolamine, and the second was its corresponding dihydroceramide base. Unexpectedly, the third compound was the glycosphingolipid α-galactosylceramide (α-GalCerBf), which is structurally related to a sponge-derived sphingolipid (α-GalCer, KRN7000) that is the prototypical agonist of CD1d-restricted natural killer T (iNKT) cells. We demonstrate that α-GalCerBf has similar immunological properties to KRN7000: it binds to CD1d and activates both mouse and human iNKT cells both in vitro and in vivo. Thus, our study reveals BF2461 as the first known member of the Bacteroides sphingolipid pathway, and it indicates that the committed steps of the Bacteroides and eukaryotic sphingolipid pathways are identical. Moreover, our data suggest that some Bacteroides sphingolipids might influence host immune homeostasis.
While human gut bacteria are thought to produce diffusible molecules that influence host biology, few of these molecules have been identified. Species of Bacteroides, a Gram-negative bacterial genus whose members often comprise >50% of the gut community, are unusual in that they produce sphingolipids, signaling molecules that play a key role in modulating the host immune response. Sphingolipid production is ubiquitous among eukaryotes but present in only a few bacterial genera. We set out to construct a Bacteroides strain that is incapable of producing sphingolipids, knocking out a gene predicted to encode the first enzymatic step in the Bacteroides sphingolipid biosynthetic pathway. The resulting mutant is indeed deficient in sphingolipid production, and we purified and solved the structures of three sphingolipids that are present in the wild-type strain but absent in the mutant. To our surprise, one of these molecules is a close chemical relative of a sponge sphingolipid that is the prototypical ligand for a host receptor that controls the activity of natural killer T cells. Like the sponge sphingolipid, the Bacteroides sphingolipid can modulate natural killer T cell activity, suggesting a novel mechanism by which Bacteroides in the gut might influence the host immune response.
We previously demonstrated immune activation in the maternal peripheral circulation associated with preterm labor (PTL). There was an elevation in WBC mRNA of anti-inflammatory complement decay-accelerating factor (CD55) and the innate-immune response activating toll-like receptor 4 (TLR4). These findings suggested that collectively, these two molecules might serve as useful biomolecules to aid in the diagnosis of PTL. In this study, we used a combined marker approach to determine whether a dual marker model utilizing both CD55 and TLR4 mRNA levels to classify PTL would increase diagnostic accuracy compared to either molecule alone. Two methods were evaluated; a linear discriminant (LD) method and a distribution free (DF) method, in order to find the optimal linear combination of TLR4 and CD55 data to diagnose PTL accurately. Our results indicated that a combined CD55-TLR4 dual marker model could provide statistically significant improvements compared to CD55 or TLR4 single marker models for PTL classification performance.
Preterm Labor (PTL); CD55; Decay Accelerating Factor (DAF); Toll-Like Receptor 4 (TLR4)
Massive palindromes in the human Y chromosome harbor mirror-image gene pairs essential for spermatogenesis. During evolution, these gene pairs have been maintained by intrapalindrome, arm-to-arm recombination. The mechanism of intrapalindrome recombination and risk of harmful effects are unknown. We report 51 patients with isodicentric Y (idicY) chromosomes formed by homologous crossing-over between opposing arms of palindromes on sister chromatids. These ectopic recombination events occur at nearly all Y-linked palindromes. Based on our findings, we propose that intrapalindrome sequence identity is maintained via noncrossover pathways of homologous recombination. DNA double-strand breaks that initiate these pathways can be alternatively resolved by crossing over between sister chromatids to form idicY chromosomes, with clinical consequences ranging from spermatogenic failure to sex reversal and Turner syndrome. Our observations imply that crossover as well as noncrossover pathways are active in nearly all Y-linked palindromes, exposing an Achilles' heel in the mechanism that preserves palindrome-borne genes.
Idiopathic scoliosis is generally treated by surgical derotation of the spine. A secondary goal of surgery is minimization of the “rib hump” deformity. Previous studies have evaluated the effects of surgical releases such as diskectomy, costo-vertebral joint release, facetectomy, and costoplasty on spine mobilization and overall contribution to thoracic stability. The present study was designed to evaluate the biomechanical effects of the rib head joints alone on axial rotation, lateral bending, and segmental rotation, without diskectomy or disruption of anterior or posterior elements.
Four female cadaver thoracic spines with intact sternums and rib cages were mounted in an Instron servo-hydraulic bi-axial MTS. In a 12-step sequence, the costo-vertebral and costo-transverse ligaments were released, first unilaterally from T10–T7, then bilaterally until complete disarticulation between the rib heads and the vertebral bodies. After each release, biomechanical testing, including axial rotation and lateral bending, was performed. Vertebral body displacement was also measured using electromagnetic trackers.
We found that rib displacement during axial rotation was significantly increased by unilateral rib head release, and torque was decreased with each successive cut. We also found increased vertebral displacement with sequential rib head release.
Our results show that sequential costo-vertebral joint releases result in a decrease in the force required for axial rotation and lateral bending, coupled with an increase in the displacement of vertebral bodies. These findings suggest that surgical release of the costo-transverse and costo-vertebral ligaments can facilitate segmental correction in scoliosis by decreasing the torso’s natural biomechanical resistance to this correction.
Rib head release; Scoliosis; Thoracic spine; Vertebrae; Costo-vertebral release
Bacterially-produced small molecules exert profound influences on animal health, morphogenesis, and evolution through poorly understood mechanisms. In one of the closest living relatives of animals, the choanoflagellate Salpingoeca rosetta, we find that rosette colony development is induced by the prey bacterium Algoriphagus machipongonensis and its close relatives in the Bacteroidetes phylum. Here we show that a rosette inducing factor (RIF-1) produced by A. machipongonensis belongs to the small class of sulfonolipids, obscure relatives of the better known sphingolipids that play important roles in signal transmission in plants, animals, and fungi. RIF-1 has extraordinary potency (femtomolar, or 10−15 M) and S. rosetta can respond to it over a broad dynamic range—nine orders of magnitude. This study provides a prototypical example of bacterial sulfonolipids triggering eukaryotic morphogenesis and suggests molecular mechanisms through which bacteria may have contributed to the evolution of animals.
All animals, including humans, evolved in a world filled with bacteria. Although bacteria are most familiar as pathogens, some bacteria produce small molecules that are essential for the biology of animals and other eukaryotes, although the details of the ways in which these bacterial molecules are beneficial are not well understood.
The choanoflagellates are water-dwelling organisms that use their whip-like flagella to move around, feeding on bacteria. They can exist as one cell or a colony of multiple cells and, perhaps surprisingly, are the closest known living relatives of animals. This means that experiments on these organisms have the potential to improve our understanding of animal development and the transition from egg to embryo to adult.
Alegado et al. have explored how the morphology of Salpingoeca rosetta, a colony-forming choanoflagellate, is influenced by its interactions with various species of bacteria. In particular, they find that the development of multicellularity in S. rosetta is triggered by the presence of the bacterium Algoriphagus machipongonensis as well as its close relatives. They also identify the signaling molecule produced by the bacteria to be C32H64NO7S; this lipid molecule is an obscure relative of the sphingolipid molecules that have important roles in signal transmission in animals, plants, and fungi. Moreover, Alegado et al. show that S. rosetta can respond to this molecule – which they call rosette-inducing factor (RIF-1) – over a wide range of concentrations, including concentrations as low as 10−17 M.
The work of Alegado et al. suggests that interactions between S. rosetta and Algoriphagus bacteria could be a productive model system for studying the influences of bacteria on animal cell biology, and for investigating the mechanisms of signal delivery and reception. Moreover, the molecular mechanisms revealed by this work leave open the possibility that bacteria might have contributed to the evolution of multicellularity in animals.
Salpingoeca rosetta; Algoriphagus; bacterial sulfonolipid; multicellular development; Other
The human X and Y chromosomes evolved from an ordinary pair of autosomes during the past 200–300 million years1–3. Due to genetic decay, the human MSY (male-specific region of Y chromosome) retains only three percent of the ancestral autosomes’ genes4,5. This evolutionary decay was driven by a series of five “stratification” events. Each event suppressed X-Y crossing over within a chromosome segment or “stratum”, incorporated that segment into the MSY, and subjected its genes to the erosive forces that attend the absence of crossing over2,6. The last of these events occurred 30 million years ago (mya), or 5 million years before the human and Old World monkey (OWM) lineages diverged. Although speculation abounds regarding ongoing decay and looming extinction of the human Y chromosome7–10, remarkably little is known about how many MSY genes were lost in the human lineage in the 25 million years that have followed its separation from the OWM lineage. To explore this question, we sequenced the MSY of the rhesus macaque, an OWM, and compared it to the human MSY. We discovered that, during the last 25 million years, MSY gene loss in the human lineage was limited to the youngest stratum (stratum 5), which comprises three percent of the human MSY. Within the older strata, which collectively comprise the bulk of the human MSY, gene loss evidently ceased more than 25 mya. Likewise, the rhesus MSY has not lost any older genes (from strata 1–4) during the past 25 million years, despite major structural differences from the human MSY. The rhesus MSY is simpler, with few amplified gene families or palindromes that might enable intrachromosomal recombination and repair. We present an empirical reconstruction of human MSY evolution in which each stratum transitioned from rapid, exponential loss of ancestral genes to strict conservation through purifying selection.
Physicians and family members frequently are asked to provide information about driving ability in patients with Alzheimer’s disease (AD), yet there has been little research on the validity of their assessments of driving performance.
Participants were recruited from the neurology department of a community hospital affiliated with Brown Medical School.
Participants included 75 older adults (17 with mild AD, 33 with very mild AD, and 25 elderly controls).
The participant him/herself, an informant, and an experienced neurologist rated each participant’s driving ability on a 3-point rating scale (safe, marginal, unsafe). A professional driving instructor also completed a standardized 108-point on-road driving assessment of each participant and then rated driving ability on the 3-point scale. Ratings were compared with the on-road driving score and with each other.
Only the neurologist’s rating of the participants’ driving abilities was significantly related to on-road driving score. When related to the instructor’s safety rating, the neurologist’s ratings were the most sensitive and specific. Mini-Mental State Examination score was a borderline covariate for the neurologist’s rating. Overall, the instructor was the most stringent rater of participant driving ability, followed by the neurologist, the informant, and the participant.
An experienced neurologist’s assessment of driving competence may be a valid predictor of driving performance of patients with early AD.
dementia; driving; assessment; Alzheimer’s disease
The purpose of this article is to review the literature on the ability of individuals with dementia to drive an automobile. Based on a review of the literature, several factors were identified that may be useful in differentiating between people with dementia who presently remain safe drivers from those who have progressed to impaired driving. These factors include disease duration and severity, sex, patient self-assessment, family assessment, neuropsychological measures, findings on road evaluations, and driving simulator testing. The approach of the physician to driving and dementia is addressed, including in-office screening, referral for on-road driving assessments, and the potential for physician reporting to state agencies.
dementia; driving; competence; impairment
The Driving Scenes test of the new Neuropsychological Assessment Battery (NAB; [Stern, R.A., & White, T. (2003a). Neuropsychological Assessment Battery. Lutz, FL: Psychological Assessment Resources, Inc.]) measures several aspects of visual attention thought to be important for driving ability. The current study examined the relationship between scores on the Driving Scenes test and on-road driving performance on a standardized driving test. Healthy participants performed significantly better on the Driving Scenes test than did very mildly demented participants. A correlation of 0.55 was found between the brief, office-based Driving Scenes test and the 108-point on-road driving score. Furthermore, the Driving Scenes test scores differed significantly across the driving instructor’s three global ratings (safe, marginal, and unsafe), and results of a discriminant function analysis indicated that the Driving Scenes test correctly classified 66% of participants into these groups. Thus, the new NAB Driving Scenes test appears to have good ecological validity for real-world driving ability in normal and very mildly demented older adults.
Driving; Aging; Dementia; Neuropsychology; Attention; Visual
The intrauterine growth restricted (IUGR) fetus develops unique metabolic adaptations in response to exposure to reduced nutrient supply. These adaptations provide survival value for the fetus by enhancing the capacity of the fetus to take up and use nutrients, thereby reducing the need for nutrient supply. Each organ and tissue in the fetus adapts differently, with the brain showing the greatest capacity for maintaining nutrient supply and growth. Such adaptations, if persistent, also have the potential in later life to promote nutrient uptake and storage, which directly lead to complications of obesity, insulin resistance, reduced insulin production, and type 2 diabetes.
Fetus; placenta; pregnancy; intrauterine growth restriction (IUGR); nutrition
Maternal dietary protein supplementation to improve fetal growth has been considered as an option to prevent or treat intrauterine growth restriction. However, in contrast to balanced dietary supplementation, adverse perinatal outcomes in pregnant women who received high amounts of dietary protein supplementation have been observed. The responsible mechanisms for these adverse outcomes are unknown. This review will discuss relevant human and animal data to provide the background necessary for the development of explanatory hypotheses and ultimately for the development therapeutic interventions during pregnancy to improve fetal growth. Relevant aspects of fetal amino acid metabolism during normal pregnancy and those pregnancies affected by IUGR will be discussed. In addition, data from animal experiments which have attempted to determine mechanisms to explain the adverse responses identified in the human trials will be presented. Finally, we will suggest new avenues for investigation into how amino acid supplementation might be used safely to treat and/or prevent IUGR.
amino acids; taurine; leucine; arginine; pregnancy; intrauterine growth restriction; insulin; metabolism; protein; dietary supplementation
We recorded via telemetry the arterial blood pressure (BP) and heart rate (HR) response to classical conditioning following the spontaneous onset of autoimmune diabetes in BBDP/Wor rats vs. age-matched, diabetes-resistant control (BBDR/Wor) rats. Our purpose was to evaluate the autonomic regulatory responses to an acute stress in a diabetic state of up to 12 months duration. The stress was a 15-s pulsed tone (CS+) followed by a 0.5-s tail shock. The initial, transient increase in BP (i.e., the “first component,” or C1), known to be derived from an orienting response and produced by a sympathetic increase in peripheral resistance, was similar in diabetic and control rats through ∼9 months of diabetes; it was smaller in diabetic rats 10 months after diabetes onset. Weakening of the C1 BP increase in rats that were diabetic for >10 months is consistent with the effects of sympathetic neuropathy. A longer-latency, smaller, but sustained “second component” (C2) conditional increase in BP, that is acquired as a rat learns the association between CS+ and the shock, and which results from an increase in cardiac output, was smaller in the diabetic vs. control rats starting from the first month of diabetes. A concomitant HR slowing was also smaller in diabetic rats. The difference in the C2 BP increase, as observed already during the first month of diabetes, is probably secondary to the effects of hyperglycemia upon myocardial metabolism and contractile function, but it may also result from effects on cognition. The small HR slowing concomitant with the C2 pressor event is probably secondary to differences in baroreflex activation or function, though parasympathetic dysfunction may contribute later in the duration of diabetes. The nearly immediate deficit after disease onset in the C2 response indicates that diabetes alters BP and HR responses to external challenges prior to the development of structural changes in the vasculature or autonomic nerves.
cardiovascular system; autonomic nervous system; dysautonomia; Pavlovian (classical) conditioning; anxiety; telemetry
Hundreds of candidate 14-3-3-binding (phospho)proteins have been reported in publications that describe one interaction at a time, as well as high-throughput 14-3-3-affinity and mass spectrometry-based studies. Here, we transcribed these data into a common format, deposited the collated data from low-throughput studies in MINT (http://mint.bio.uniroma2.it/mint), and compared the low- and high-throughput data in VisANT graphs that are easy to analyze and extend. Exploring the graphs prompted questions about technical and biological specificity, which were addressed experimentally, resulting in identification of phosphorylated 14-3-3-binding sites in the mitochondrial import sequence of the iron-sulfur cluster assembly enzyme (ISCU), cytoplasmic domains of the mitochondrial fission factor (MFF), and endoplasmic reticulum-tethered receptor expression-enhancing protein 4 (REEP4), RNA regulator SMAUG2, and cytoskeletal regulatory proteins, namely debrin-like protein (DBNL) and kinesin light chain (KLC) isoforms. Therefore, 14-3-3s undergo physiological interactions with proteins that are destined for diverse subcellular locations. Graphing and validating interactions underpins efforts to use 14-3-3-phosphoproteomics to identify mechanisms and biomarkers for signaling pathways in health and disease.
Circadian changes in cardiovascular function during the progression of diabetes mellitus in the diabetes prone rat (BBDP) (n = 8) were studied. Age-matched diabetes-resistant rats (BBDR) served as controls. BP was recorded via telemetry in contiguous 4 hr time periods over 24 hours starting with 12 midnight to 4 am as period zero (P0). Prior to onset of diabetes BP was high at P0, peaked at P2, and then fell again at P3; BP and heart rate (HR) then increased gradually at P4 and leveled off at P5, thereby exhibiting a bipodal rhythm. These patterns changed during long-term diabetes. The cross-correlation coefficient of BP and HR was not significantly different across groups at onset, but it fell significantly at 9 months of duration of diabetes (BBDP: 0.39 ± 0.06; BBDR: 0.65 ± 0.03; P < .05). These results show that changes in circadian cardiovascular rhythms in diabetes mellitus became significant at the late stage of the disease.
A 60-year-old woman presented after a fall and was noted to have ascites. She had a history of ulcerative colitis. History and physical examination did not reveal the likely aetiology of the ascites, but a sample showed it to be a blood-stained exudate. A malignant cause appeared likely, cross-sectional imaging was arranged and tumour markers sent. CA125 was 34 IU/ml (0–30); α-fetoprotein (AFP) and carcinoembryonic antigen (CEA) were normal. However, CA19-9 was 2880 U/ml (0–31). Pancreatic carcinoma or cholangiocarcinoma were of prime concern, but a CT scan and MRI imaging were normal. At laparoscopy a benign ruptured ovarian cyst was detected, and ascites drained. CA19-9 returned to normal and the patient remains well 9 months later. This case demonstrates how tumour markers may be misleading in the context of diagnostics, and is the highest reported example of CA19-9 rise in the context of benign ascites and benign ovarian pathology.
In birds, as in mammals, one pair of chromosomes differs between the sexes. In birds, males are ZZ and females ZW. In mammals, males are XY and females XX. Like the mammalian XY pair, the avian ZW pair is believed to have evolved from autosomes, with most change occurring in the chromosomes found in only one sex – the W and Y chromosomes1–5. By contrast, the sex chromosomes found in both sexes – the Z and X chromosomes – are assumed to have diverged little from their autosomal progenitors2. Here we report findings that overturn this assumption for both the chicken Z and human X chromosomes. The chicken Z chromosome, which we sequenced essentially to completion, is less gene-dense than chicken autosomes but contains a massive tandem array containing hundreds of duplicated genes expressed in testes. A comprehensive comparison of the chicken Z chromosome to the finished sequence of the human X chromosome demonstrates that each evolved independently from different portions of the ancestral genome. Despite this independence, the chicken Z and human X chromosomes share features that distinguish them from autosomes: the acquisition and amplification of testis-expressed genes, as well as a low gene density resulting from an expansion of intergenic regions. These features were not present on the autosomes from which the Z and X chromosomes originated but were instead acquired during the evolution of the Z and X as sex chromosomes. We conclude that the avian Z and mammalian X chromosomes followed convergent evolutionary trajectories, despite their evolving with opposite (female vs. male) systems of heterogamety. More broadly, in birds and mammals, sex chromosome evolution involved not only gene loss in sex-specific chromosomes, but also marked expansion and gene acquisition in sex chromosomes common to males and females.
Both phosphorylated (p) mTOR and p70S6K are known to regulate protein synthesis and are affected during intrauterine growth restriction (IUGR). We studied the mTOR pathway during hyperthermia (HT) induced IUGR in the sheep.
Beginning at 40 dGA, four ewes were exposed to HT for 55 days and four were exposed for 80 to induce IUGR. Western blot analyses were performed for mTOR, p70S6K, 4EBP1, ERK, and AKT.
HT animals had: smaller fetuses and placentas near-term, reduced placental weight at mid-gestation, increased p-mTOR, p-ERK and p-AKT and decreased p70S6K in the near-term cotyledons, and decreased p- p70S6K and increased p-ERK in the caruncles (maternal) near-term.
Near-term IUGR ovine cotyledons showed upregulation of p-mTOR, while p70S6K was decreased. This suggest that the changes in placental mTOR signaling proteins could be driven by the fetal stress observed near-term in this model of IUGR.
Nonglucose carbohydrates such as galactose, mannose, and inositol play a clinically important role in fetal and neonatal nutrition, though little is known about their metabolism in the neonate. The aim of this study was to determine whether postprandial changes in plasma carbohydrate and sugar alcohol concentrations are affected by clinical variables such as postnatal age (PNA), milk type, feeding volume, or feeding duration in term newborns. Neonates (n = 26) taking intermittent enteral feedings were enrolled. Blood samples were obtained at baseline (immediately before the start of a feeding) and at 2–3 subsequent time points up to 110 min. Postprandial rise was only observed for plasma glucose concentrations [Glu] and plasma galactose concentrations [Gal] and clinical variables did not predict this change. Despite equimolar delivery in milk, the median of [Glu] rise minus [Gal] rise from baseline to second postprandial plasma sample was 674 μM (−38, 3333 μM; p < 0.0001), reflecting efficient hepatic first-pass metabolism of galactose. A significant PNA effect on [Gal] was observed such that for each day PNA there was an 18% decrease in [Gal] (p = 0.03). [Gal] are a function of PNA, suggesting maintenance of a significant ductus venosus shunt in term infants.
A wide variety of agents activate AMPK, but in many cases the mechanisms remain unclear. We generated isogenic cell lines stably expressing AMPK complexes containing AMP-sensitive (wild-type, WT) or AMP-insensitive (R531G) γ2 variants. Mitochondrial poisons such as oligomycin and dinitrophenol only activated AMPK in WT cells, as did AICAR, 2-deoxyglucose, hydrogen peroxide, metformin, phenformin, galegine, troglitazone, phenobarbital, resveratrol, and berberine. Excluding AICAR, all of these also inhibited cellular energy metabolism, shown by increases in ADP:ATP ratio and/or by decreases in cellular oxygen uptake measured using an extracellular flux analyzer. By contrast, A769662, the Ca2+ ionophore, A23187, osmotic stress, and quercetin activated both variants to varying extents. A23187 and osmotic stress also increased cytoplasmic Ca2+, and their effects were inhibited by STO609, a CaMKK inhibitor. Our approaches distinguish at least six different mechanisms for AMPK activation and confirm that the widely used antidiabetic drug metformin activates AMPK by inhibiting mitochondrial respiration.
► AMPK is activated by a wide variety of different stresses, drugs, and xenobiotics ► We have developed a sensitive method to test which activators are AMP mediated ► Most, e.g., metformin and resveratrol, inhibit mitochondrial function and elevate AMP ► However, we can now distinguish six different mechanisms for AMPK activation
Autosomal dominant parkinsonism, hypoventilation, depression and severe weight loss (Perry syndrome) is an early-onset rapidly progressive disease. At autopsy, previous studies have found severe neuronal loss in the substantia nigra without Lewy bodies. Transactive response DNA-binding protein of 43 kDa (TDP-43) has recently been identified as a major ubiquitinated constituent of neuronal and glial inclusions in frontotemporal lobar degeneration with ubiquitin-positive inclusions and in amyotrophic lateral sclerosis. This study reports clinical, genetic and neuropathologic investigations of Perry syndrome.
Clinical data and autopsy brain tissue samples were collected from eight patients from four genealogically unrelated kindreds with Perry syndrome. Brain tissue was studied with immunohistochemistry and biochemistry for TDP-43. Patients were screened for mutations in the progranulin (GRN) and TDP-43 (TARDBP) genes.
The mean age at onset was 47 years (range: 40-56), and the mean age at death was 52 years (range: 44-64). In all patients, we identified TDP-43-positive neuronal inclusions, dystrophic neurites and axonal spheroids in a predominantly pallidonigral distribution, and we demonstrated changes in solubility and electrophoretic mobility of TDP-43 in brain tissue. The inclusions were highly pleomorphic and predominated in the extrapyramidal system, sparing the cortex, hippocampus and motor neurons. There were no mutations in GRN or TARDBP.
Perry syndrome displays unique TDP-43 pathology that is selective for the extrapyramidal system and spares the neocortex and motor neurons.
autosomal dominant; axonal dystrophy; neuronal cytoplasmic inclusions; pallidonigral; parkinsonism; Perry syndrome; TARDBP; TDP-43
Perry syndrome consists of early-onset parkinsonism, depression, severe weight loss and hypoventilation, in which brain pathology is characterized by TDP-43 immunostaining. Through genome-wide linkage analysis we have identified five disease-segregating dynactin (DCTN1) CAP-Gly domain substitutions in 8 families that diminish microtubule binding and lead to intracytoplasmic inclusions. DCTN1 mutations were previously associated with motor neuron disease but can underlie the selective vulnerability of other neuronal populations in distinct neurodegenerative disorders.
Dynactin; DCTN1; Perry syndrome; parkinsonism; neurodegeneration; TDP-43
Nutritional interventions for IUGR have raised concerns for fetal toxicity, the mechanisms of which are unknown. Most of these attempts did not aim to normalize fetal metabolic conditions. Therefore, we used a model of IUGR to determine if normalization of fetal hypoglycemia for two weeks would be tolerated and increase insulin concentrations and pancreatic β-cell mass. IUGR fetuses received either a direct saline infusion (Sal, the control group) or a 30% dextrose infusion (Glu) to normalize glucose concentrations. Neither insulin concentrations (0.11±0.01 Glu vs. 0.10±0.01 ng/ml Sal) nor β-cell mass (65.2±10.3 Glu vs. 74.7±18.4 mg Sal) changed. Glucose stimulated insulin secretion (GSIS) was lower in the Glu group. Glu fetuses became progressively more hypoxic: O2 content 1.4±0.5 Glu vs. 2.7±0.4 mmol/L Sal, p<0.05. PaCO2 (53.6±0.8 Glu vs. 51.6±0.8 Sal, p<0.05) and lactate (7.74±3.82 Glu vs. 2.47±0.55 mmol/L Sal, p<0.0001) were greater and pH lower (7.275±0.071 Glu vs. 7.354±0.003 Sal, p<0.01) in the Glu group. We conclude that correction of fetal hypoglycemia is not well tolerated and fails to increase insulin concentrations or β-cell mass in IUGR fetuses.
intrauterine growth restriction; glucose; insulin; fetus; beta-cell
Aeromonas salmonicida subsp. salmonicida is a Gram-negative bacterium that is the causative agent of furunculosis, a bacterial septicaemia of salmonid fish. While other species of Aeromonas are opportunistic pathogens or are found in commensal or symbiotic relationships with animal hosts, A. salmonicida subsp. salmonicida causes disease in healthy fish. The genome sequence of A. salmonicida was determined to provide a better understanding of the virulence factors used by this pathogen to infect fish.
The nucleotide sequences of the A. salmonicida subsp. salmonicida A449 chromosome and two large plasmids are characterized. The chromosome is 4,702,402 bp and encodes 4388 genes, while the two large plasmids are 166,749 and 155,098 bp with 178 and 164 genes, respectively. Notable features are a large inversion in the chromosome and, in one of the large plasmids, the presence of a Tn21 composite transposon containing mercury resistance genes and an In2 integron encoding genes for resistance to streptomycin/spectinomycin, quaternary ammonia compounds, sulphonamides and chloramphenicol. A large number of genes encoding potential virulence factors were identified; however, many appear to be pseudogenes since they contain insertion sequences, frameshifts or in-frame stop codons. A total of 170 pseudogenes and 88 insertion sequences (of ten different types) are found in the A. salmonicida genome. Comparison with the A. hydrophila ATCC 7966T genome reveals multiple large inversions in the chromosome as well as an approximately 9% difference in gene content indicating instances of single gene or operon loss or gain.
A limited number of the pseudogenes found in A. salmonicida A449 were investigated in other Aeromonas strains and species. While nearly all the pseudogenes tested are present in A. salmonicida subsp. salmonicida strains, only about 25% were found in other A. salmonicida subspecies and none were detected in other Aeromonas species.
Relative to the A. hydrophila ATCC 7966T genome, the A. salmonicida subsp. salmonicida genome has acquired multiple mobile genetic elements, undergone substantial rearrangement and developed a significant number of pseudogenes. These changes appear to be a consequence of adaptation to a specific host, salmonid fish, and provide insights into the mechanisms used by the bacterium for infection and avoidance of host defence systems.