107 results on '"McDonald AG"'
Search Results
2. Editorial
- Author
-
McDonald, AG, primary
- Published
- 1981
- Full Text
- View/download PDF
3. Case records of the Massachusetts General Hospital. Case 35-2011: A 33-year-old woman with postpartum leukocytosis and Gram-positive bacteremia.
- Author
-
Soper DE, Lee SI, Kim JY, and McDonald AG
- Published
- 2011
4. Nephrogenic systemic fibrosis: a pathologic study of autopsy cases.
- Author
-
Koreishi AF, Nazarian RM, Saenz AJ, Klepeis VE, McDonald AG, Farris AB, Colvin RB, Duncan LM, Mandal RV, and Kay J
- Published
- 2009
- Full Text
- View/download PDF
5. Placenta and Intestinal Injury in Preterm Infants.
- Author
-
Garg P, Weitkamp JH, McDonald AG, Cilvik SN, Mir I, Shenberger JS, Olaloye O, Konnikova L, Kallapur SG, and Garg PM
- Abstract
Necrotizing enterocolitis (NEC) is one of the most common gastrointestinal conditions affecting 6 to 10% of low-birth-weight infants and remains a leading cause of death. The risk factors associated with NEC are complex and multifactorial, including preterm birth and intrauterine exposure to inflammation and hypoxia. Chorioamnionitis has been associated with intestinal injury in animal and human clinical studies. This review presents current evidence about the clinical impact of the intrauterine environment on intestinal injury during pregnancy and postpregnancy. We present information from our own clinical and laboratory research in conjunction with information collected from an extensive search in the databases PubMed, EMBASE, and Scopus. Prospective multicenter studies, including accurate and precise clinical, maternal, and laboratory predictors (e.g., inflammatory biomarkers), will help identify the mechanisms associated with the placental pathology, the development of NEC, and the impact of in utero-triggered inflammation on the clinical outcomes. Filling the knowledge gap to link the inflammatory surge to postnatal life will aid in identifying at-risk infants for NEC in a timely manner and facilitate the development of novel immunomodulatory treatments or interventions to improve the outcomes of these vulnerable infants. KEY POINTS: · Placental inflammatory and vascular lesions are associated with NEC severity.. · Higher grade chorioamnionitis with a fetal response is associated with an increased risk of surgical NEC.. · There is a need for routine bedside utilization of placenta pathology in clinical decision-making.., Competing Interests: None declared., (Thieme. All rights reserved.)
- Published
- 2024
- Full Text
- View/download PDF
6. Simulated digestions of free oligosaccharides and mucin-type O-glycans reveal a potential role for Clostridium perfringens.
- Author
-
McDonald AG and Lisacek F
- Subjects
- Infant, Newborn, Humans, Bifidobacterium, Mucins analysis, Oligosaccharides analysis, Milk, Human chemistry, Bacteria, Glycoside Hydrolases analysis, Digestion, Clostridium perfringens, Bifidobacterium bifidum
- Abstract
The development of a stable human gut microbiota occurs within the first year of life. Many open questions remain about how microfloral species are influenced by the composition of milk, in particular its content of human milk oligosaccharides (HMOs). The objective is to investigate the effect of the human HMO glycome on bacterial symbiosis and competition, based on the glycoside hydrolase (GH) enzyme activities known to be present in microbial species. We extracted from UniProt a list of all bacterial species catalysing glycoside hydrolase activities (EC 3.2.1.-), cross-referencing with the BRENDA database, and obtained a set of taxonomic lineages and CAZy family data. A set of 13 documented enzyme activities was selected and modelled within an enzyme simulator according to a method described previously in the context of biosynthesis. A diverse population of experimentally observed HMOs was fed to the simulator, and the enzymes matching specific bacterial species were recorded, based on their appearance of individual enzymes in the UniProt dataset. Pairs of bacterial species were identified that possessed complementary enzyme profiles enabling the digestion of the HMO glycome, from which potential symbioses could be inferred. Conversely, bacterial species having similar GH enzyme profiles were considered likely to be in competition for the same set of dietary HMOs within the gut of the newborn. We generated a set of putative biodegradative networks from the simulator output, which provides a visualisation of the ability of organisms to digest HMO and mucin-type O-glycans. B. bifidum, B. longum and C. perfringens species were predicted to have the most diverse GH activity and therefore to excel in their ability to digest these substrates. The expected cooperative role of Bifidobacteriales contrasts with the surprising capacities of the pathogen. These findings indicate that potential pathogens may associate in human gut based on their shared glycoside hydrolase digestive apparatus, and which, in the event of colonisation, might result in dysbiosis. The methods described can readily be adapted to other enzyme categories and species as well as being easily fine-tuneable if new degrading enzymes are identified and require inclusion in the model., (© 2024. The Author(s).)
- Published
- 2024
- Full Text
- View/download PDF
7. Physicochemical Characterization of Woody Lignocellulosic Biomass and Charcoal for Bio-energy Heat Generation.
- Author
-
Olabisi AS, Balogun AO, Oni TO, Fakinle BS, Sotoudehnia F, McDonald AG, and Ikubanni PP
- Subjects
- Biomass, Wood, Kinetics, Thermogravimetry, Charcoal chemistry, Hot Temperature
- Abstract
Biomass and its interactions for heat generation have received little attention. In this study, the woody biomass materials were Prosopis africana (PA), Harungana madascariences (HM), Vitrllaria paradoxa (VP), and Afzelia africana (AA). The composition (extractives, carbohydrate, and lignin) of the biomass was determined. The biomass was converted to charcoal in a traditional kiln. A thermo-kinetic examination of the charcoal samples was carried out. The kinetic parameters and potential reaction mechanisms involved in the decomposition process were both obtained using the integral (Flynn-Wall Ozawa) isoconversional methods in conjunction with the Coats-Redfern approach. The activation energy profiles for the charcoal samples in oxidizing atmospheres were 548 kJ/mol for AA, 274 kJ/mol for VP, 548 kJ/mol for PA, and 274 kJ/mol for HM. All charcoal samples underwent comprehensive, multi-step, complex reaction pathways for thermal degradation. The charcoal samples exhibit not only great potential for biochemical extraction but also for bioenergy applications. The significant amount of combustion characteristics in the raw biomass and charcoal samples indicates that each type of wood charcoal produced has more fixed carbon, less ash, and less volatile matter, all of which are desirable for the thermo-chemical conversion of biomass for the production of heat., (© 2023. The Author(s).)
- Published
- 2023
- Full Text
- View/download PDF
8. Clinical Correlates of Cholestasis in Preterm Infants with Surgical Necrotizing Enterocolitis.
- Author
-
Garg PM, Pittman I, Yi J, Weis VG, Rodriguez RJ, Ladd MR, Rauh JL, McDonald AG, Welch C, Premkumar MH, Garg PP, and Maheshwari A
- Abstract
Background: We sought to investigate the clinical determinants and outcomes of cholestasis in preterm infants with surgical necrotizing enterocolitis (sNEC)., Methods: Retrospective comparison of clinical information in preterm infants who developed cholestasis vs those who did not., Results: Sixty-two (62/91, 68.1%) infants with NEC developed cholestasis at any time following the onset of illness. Cholestasis was seen more frequently in those who had received ionotropic support at 24 hours following sNEC diagnosis (87.1% vs 58.6%; p = 0.002), had higher mean C-reactive protein levels 2 weeks after NEC diagnosis ( p = 0.009), had blood culture-positive sepsis [25 (40.3%) vs 4 (13.8%); p = 0.011], received parenteral nutrition (PN) for longer durations (108.4 ± 56.63 days vs 97.56 ± 56.05 days; p = 0.007), had higher weight-for-length z scores at 36 weeks' postmenstrual age [-1.0 (-1.73, -0.12) vs -1.32 (-1.76, -0.76); p = 0.025], had a longer length of hospital stay (153.7 ± 77.57 days vs 112.51 ± 85.22 days; p = 0.024), had intestinal failure more often (61% vs 25.0%, p = 0.003), had more surgical complications (50% vs 27.6%; p = 0.044), and had >1 complication (21% vs 3.4%; p = 0.031). Using linear regression, the number of days after surgery when feeds could be started [OR 15.4; confidence interval (CI) 3.71, 27.13; p = 0.009] and the postoperative ileus duration (OR 11.9, CI 1.1, 22.8; p = 0.03) were independently associated with direct bilirubin between 2 and 5 mg/dL (mild-moderate cholestasis) at 2 months of age. The duration of PN was independently associated with direct bilirubin >5 mg/dL (severe cholestasis) at 2 months of age in these patients., Conclusion: Cholestasis was seen in 68% of infants following surgical NEC. The most likely contributive factors are intestinal failure and subsequent PN dependence for longer periods. Our data suggest that identification and prevention of risk factors such as sepsis and surgical complications and early feeds following NEC surgery may improve outcomes., Competing Interests: Conflict of interest: Dr Muralidhar Hebbur Premkumar and Dr Akhil Maheshwari are associated as the Editorial Board Members of this journal and this manuscript was subjected to this journal’s standard review procedures, with this peer review handled independently of these Editorial Board Members and their research group.
- Published
- 2023
- Full Text
- View/download PDF
9. Evaluation of the Mechanical, Thermal and Rheological Properties of Hop, Hemp and Wood Fiber Plastic Composites.
- Author
-
Talcott S, Uptmor B, and McDonald AG
- Abstract
The aim of this study was to evaluate the use of waste natural fibers from milled hop bines and hemp stalks, without chemical treatment, and compare them to a commercial wood fiber for use in wood-plastic composite (WPC) materials. The fibers were characterized (density, fiber size and chemical composition). WPCs were produced by the extrusion of a blend of fibers (50%), high-density polyethylene (HDPE) and coupling agent (2%). The WPCs were characterized for their mechanical, rheological, thermal, viscoelastic and water resistance properties. Pine fiber was about half the size of hemp and hop fibers and thus had a higher surface area. The pine WPC melts had a higher viscosity than the other two WPCs. Additionally, the tensile and flexural strengths of the pine WPC were higher than those of hop and hemp WPCs. The pine WPC was also shown to have the least water absorption followed by hop and hemp WPCs. This study highlights that different lignocellulosic fibers influence their WPC properties. The properties of the hop- and hemp-based WPCs were comparable to commercial WPCs and can be improved by further milling/screening the fibers to a smaller particle size (volumetric mean of ~88 μm) to increase their surface area, fiber-matrix interactions and improve stress-transfer.
- Published
- 2023
- Full Text
- View/download PDF
10. Enzyme nomenclature and classification: the state of the art.
- Author
-
McDonald AG and Tipton KF
- Subjects
- Isomerases, Transferases, Hydrolases, Ligases, Enzymes chemistry, Oxidoreductases, Lyases
- Abstract
The IUBMB enzyme classification system, available at the IUBMB ExplorEnz website, uses a four-component number (the EC number) that identifies an enzyme in terms of reaction catalysed. There were originally six recognized groups of enzymes: Oxidoreductases (EC 1), Transferases (EC 2), Hydrolases (EC 3), Lyases (EC 4), Isomerases (EC 5) and Ligases (EC 6). Of these, the lyases, which are defined as 'enzymes that cleave C-C, C-O, C-N and other bonds by means other than by hydrolysis or oxidation', present particular recognition and classification problems. Recently, a new class, the Translocases (EC 7), has been added, which incorporates enzymes that catalyse the movement of ions or molecules across membranes or their separation within membranes. A new subclass of the isomerases has also been included for those enzymes that alter the conformations of proteins and nucleic acids. Newly reported enzymes are being regularly added to the list after validation and where new information affects the classification of an existing entry, a new EC number is created, but the old one is not reused., (© 2021 Federation of European Biochemical Societies.)
- Published
- 2023
- Full Text
- View/download PDF
11. Video-rate Raman-based metabolic imaging by Airy light-sheet illumination and photon-sparse detection.
- Author
-
Dunn L, Luo H, Subedi NR, Kasu R, McDonald AG, Christodoulides DN, and Vasdekis AE
- Subjects
- Photons, Imaging, Three-Dimensional methods, Lighting, Microscopy methods
- Abstract
Despite its massive potential, Raman imaging represents just a modest fraction of all research and clinical microscopy to date. This is due to the ultralow Raman scattering cross-sections of most biomolecules that impose low-light or photon-sparse conditions. Bioimaging under such conditions is suboptimal, as it either results in ultralow frame rates or requires increased levels of irradiance. Here, we overcome this tradeoff by introducing Raman imaging that operates at both video rates and 1,000-fold lower irradiance than state-of-the-art methods. To accomplish this, we deployed a judicially designed Airy light-sheet microscope to efficiently image large specimen regions. Further, we implemented subphoton per pixel image acquisition and reconstruction to confront issues arising from photon sparsity at just millisecond integrations. We demonstrate the versatility of our approach by imaging a variety of samples, including the three-dimensional (3D) metabolic activity of single microbial cells and the underlying cell-to-cell variability. To image such small-scale targets, we again harnessed photon sparsity to increase magnification without a field-of-view penalty, thus, overcoming another key limitation in modern light-sheet microscopy.
- Published
- 2023
- Full Text
- View/download PDF
12. Clinical determinants of intestinal failure and death in preterm infants with surgical necrotizing enterocolitis.
- Author
-
Garg PM, Denton MX, Talluri R, Ansari MAY, Riddick R, Ostrander MM, McDonald AG, Premkumar MH, Hillegass WB, and Garg PP
- Subjects
- Pregnancy, Infant, Infant, Newborn, Female, Humans, Infant, Premature, Birth Weight, Retrospective Studies, Enterocolitis, Necrotizing epidemiology, Enterocolitis, Necrotizing surgery, Intestinal Failure, Infant, Newborn, Diseases, Ileus epidemiology
- Abstract
Objective: We sought to investigate the clinical determinants of intestinal failure and death in preterm infants with surgical NEC., Methods: Retrospective comparison of clinical information between Group A = intestinal failure (Parenteral nutrition (PN) >90 days) and death and Group B = survivors and with PN dependence < 90 days in preterm infants with surgical NEC., Results: Group A (n = 99/143) had a lower mean gestational age (26.4 weeks [SD3.5] vs. 29.4 [SD 3.5]; p = 0.013), lower birth weight (873 gm [SD 427g] vs. 1425 gm [894g]; p = <0.001), later age of NEC onset (22 days [SD20] vs. 16 days [SD 17]; p = 0.128), received surgery later (276 hours [SD 544] vs. 117 hours [SD 267]; p = 0.032), had cholestasis, received dopamine (80.6% vs. 58.5%; p = 0.010) more frequently and had longer postoperative ileus time (19.8 days [SD 15.4] vs. 11.8 days [SD 6.5]; p = <0.001) and reached full feeds later (93 days [SD 45] vs. 44 [SD 22]; p = <0.001) than Group B.On multivariate logistic regression, higher birth weight was associated with lower risk (OR 0.35, 95% CI 0.15-0.82; p = 0.016) of TPN > 90 days or death. Longer length of bowel resected (OR 1.76, 95% CI 1.02-3.02; p = 0.039) and longer postoperative ileus (OR 2.87, 95% CI 1.26-6.53; p = 0.011) were also independently associated with TPN >90days or death adjusted for gestational age and antenatal steroid treatment., Conclusion: In preterm infants with surgical NEC, clinical factors such as lower birth weight, longer bowel loss, and postoperative ileus days were significantly and independently associated with TPN >90 days or death.
- Published
- 2023
- Full Text
- View/download PDF
13. Development of a multi-year white-nose syndrome mitigation strategy using antifungal volatile organic compounds.
- Author
-
Gabriel KT, McDonald AG, Lutsch KE, Pattavina PE, Morris KM, Ferrall EA, Crow SA Jr, and Cornelison CT
- Subjects
- Humans, Animals, Antifungal Agents pharmacology, Nose, Syndrome, Volatile Organic Compounds pharmacology, Chiroptera
- Abstract
Pseudogymnoascus destructans is a fungal pathogen responsible for a deadly disease among North American bats known as white-nose syndrome (WNS). Since detection of WNS in the United States in 2006, its rapid spread and high mortality has challenged development of treatment and prevention methods, a significant objective for wildlife management agencies. In an effort to mitigate precipitous declines in bat populations due to WNS, we have developed and implemented a multi-year mitigation strategy at Black Diamond Tunnel (BDT), Georgia, singly known as one of the most substantial winter colony sites for tricolored bats (Perimyotis subflavus), with pre-WNS abundance exceeding 5000 individuals. Our mitigation approach involved in situ treatment of bats at the colony level through aerosol distribution of antifungal volatile organic compounds (VOCs) that demonstrated an in vitro ability to inhibit P. destructans conidia germination and mycelial growth through contact-independent exposure. The VOCs evaluated have been identified from microbes inhabiting naturally-occurring fungistatic soils and endophytic fungi. These VOCs are of low toxicity to mammals and have been observed to elicit antagonism of P. destructans at low gaseous concentrations. Cumulatively, our observations resolved no detrimental impact on bat behavior or health, yet indicated a potential for attenuation of WNS related declines at BDT and demonstrated the feasibility of this novel disease management approach., Competing Interests: The authors have declared that no competing interests exist., (Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.)
- Published
- 2022
- Full Text
- View/download PDF
14. Effect of 3-Hydroxyvalerate Content on Thermal, Mechanical, and Rheological Properties of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Biopolymers Produced from Fermented Dairy Manure.
- Author
-
Abbasi M, Pokhrel D, Coats ER, Guho NM, and McDonald AG
- Abstract
Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with various 3-hydroxyvalerate (3HV) contents biosynthesized by mixed microbial consortia (MMC) fed fermented dairy manure at the large-scale level was assessed over a 3-month period. The thermal, mechanical, and rheological behavior and the chemical structure of the extracted PHBV biopolymers were studied. The recovery of crude PHBV extracted in a large Soxhlet extractor with CHCl
3 for 24 h ranged between 20.6% to 31.8% and purified to yield between 8.9% to 26.9% all based on original biomass.13 C-NMR spectroscopy revealed that the extracted PHBVs have a random distribution of 3HV and 3-hydroxybutyrate (3HB) units and with 3HV content between 16% and 24%. The glass transition temperature ( Tg ) of the extracted PHBVs varied between -0.7 and -7.4 °C. Some of the extracted PHBVs showed two melting temperatures ( Tm ) which the lower Tm 1 ranged between 126.1 °C and 159.7 °C and the higher Tm 2 varied between 152.1 °C and 170.1 °C. The weight average molar mass of extracted PHBVs was wide ranging from 6.49 × 105 g·mol-1 to 28.0 × 105 g·mol-1 . The flexural and tensile properties were also determined. The extracted polymers showed a reverse relationship between the 3HV content and Young's modulus, tensile strength, flexural modulus, and flexural strength properties.- Published
- 2022
- Full Text
- View/download PDF
15. In silico analysis of the human milk oligosaccharide glycome reveals key enzymes of their biosynthesis.
- Author
-
McDonald AG, Mariethoz J, Davey GP, and Lisacek F
- Subjects
- Bacteria, Female, Humans, Infant, Newborn, Lactation, Oligosaccharides chemistry, Gastrointestinal Microbiome, Milk, Human chemistry
- Abstract
Human milk oligosaccharides (HMOs) form the third most abundant component of human milk and are known to convey several benefits to the neonate, including protection from viral and bacterial pathogens, training of the immune system, and influencing the gut microbiome. As HMO production during lactation is driven by enzymes that are common to other glycosylation processes, we adapted a model of mucin-type GalNAc-linked glycosylation enzymes to act on free lactose. We identified a subset of 11 enzyme activities that can account for 206 of 226 distinct HMOs isolated from human milk and constructed a biosynthetic reaction network that identifies 5 new core HMO structures. A comparison of monosaccharide compositions demonstrated that the model was able to discriminate between two possible groups of intermediates between major subnetworks, and to assign possible structures to several previously uncharacterised HMOs. The effect of enzyme knockouts is presented, identifying β-1,4-galactosyltransferase and β-1,3-N-acetylglucosaminyltransferase as key enzyme activities involved in the generation of the observed HMO glycosylation patterns. The model also provides a synthesis chassis for the most common HMOs found in lactating mothers., (© 2022. The Author(s).)
- Published
- 2022
- Full Text
- View/download PDF
16. Differential Expression of CB 1 Cannabinoid Receptor and Cannabinoid Receptor Interacting Protein 1a in Labor.
- Author
-
Kozakiewicz ML, Zhang J, Leone-Kabler S, Yamaleyeva LM, McDonald AG, Brost BC, and Howlett AC
- Subjects
- Carrier Proteins genetics, Endocannabinoids metabolism, Female, Humans, Placenta metabolism, Pregnancy, Receptors, Cannabinoid metabolism, Cannabinoids metabolism
- Abstract
Background: The endocannabinoid system is present in multiple organ systems and is involved in smooth muscle regulation, immune function, neuroendocrine modulation, and metabolism of tissues. Limited data are available regarding the presence and role of this system in reproductive tissues. Components of the endocannabinoid system have been identified in myometrial and placental tissues. However, no study has investigated differential expression of the endocannabinoid system in labor. Objectives: The purpose of this study was to identify and quantify two components of the endocannabinoid system, the CB
1 cannabinoid receptor and cannabinoid receptor interacting protein 1a (CRIP1a) in uterine and placental tissues, and to determine if there is differential expression in tissues exposed to labor. We hypothesized that CB1 cannabinoid receptor concentration would be altered in uterine and placental tissue exposed to labor compared with tissues not exposed to labor. Study Design: Uterine and placental tissue samples were collected in nine laboring and 11 nonlaboring women undergoing cesarean delivery. CB1 cannabinoid receptor and CRIP1a presence and quantification were evaluated using western blot, immunohistochemistry, and real-time quantitative polymerase chain reaction. Statistical comparisons of laboring and nonlaboring subjects were made for uterine and placental tissue using a Mann-Whitney test. Results: Immunohistochemistry demonstrated positive staining for CB1 cannabinoid receptors and CRIP1a in uterine tissue. The protein abundance of CB1 cannabinoid receptor in uterine tissue was significantly lower in tissues exposed to labor ( p =0.01). The protein abundance of CRIP1a was lower in uterine tissue exposed to labor but did not reach statistical significance ( p =0.06). mRNA expression of CB1 cannabinoid receptor ( p =0.20) and CRIP1a ( p =0.63) did not differ in labored compared with nonlabored uterine tissues. Conclusions: Our findings of diminished protein density of CB1 cannabinoid receptor in uterine tissue exposed to labor support the hypothesis that the endocannabinoid system plays a role in parturition. Our data add to the growing body of evidence indicating the endocannabinoid system is of importance for successful reproduction and support the need for additional research investigating this complex system as it pertains to labor. ClinicalTrials.gov ID: NCT03752021.- Published
- 2022
- Full Text
- View/download PDF
17. ROADWAY-ASSOCIATED CULVERTS MAY SERVE AS A TRANSMISSION CORRIDOR FOR PSEUDOGYMNOASCUS DESTRUCTANS AND WHITE-NOSE SYNDROME IN THE COASTAL PLAINS AND COASTAL REGION OF GEORGIA, USA.
- Author
-
Lutsch KE, McDonald AG, Gabriel KT, and Cornelison CT
- Subjects
- Animals, Canada, Disease Susceptibility veterinary, Georgia, Syndrome, Ascomycota, Chiroptera microbiology, Hibernation
- Abstract
White-nose syndrome (WNS) is a disease among hibernating North American bats caused by the psychrophilic fungus Pseudogymnoascus destructans. Since its discovery in New York state, US, in 2006, and as of 2020, WNS has rapidly spread to 34 American states and seven Canadian provinces, causing precipitous declines of native bat populations across North America. The rapid spread of this fungal pathogen has been facilitated by the social behavior of bats, as well as the ability of subterranean hibernacula to support a favorable environment for P. destructans, and is probably exacerbated by anthropogenic transmission events. Although many bat species roost in natural cave environments, bats also selectively use diverse structures for hibernacula. Certain areas of the US lack caves, forcing bats to select different winter roosting environments. Bats have been observed using roadway-associated structures, such as bridges and culverts, for roosting, especially in regions that lack natural cave environments. However, the potential for P. destructans transmission in such roadway-associated structures requires further investigation. Understanding potential pathogen transmission in these widely used anthropogenic structures is crucial to disease management and preventing further declines of imperiled bat populations. Our study investigated these structures as potential pathogen transmission corridors by surveying the use of these structures by Perimyotis subflavus and other susceptible bat populations and by measuring their temperature. The results suggest the environments of roadway-associated culverts are thermally conducive to the proliferation of P. destructans-even in regions with mild winters-and the development of WNS in susceptible bat populations. It is apparent these roadway-associated structures have the potential to spread P. destructans and exacerbate the effect of WNS on susceptible bat populations., (© Wildlife Disease Association 2022.)
- Published
- 2022
- Full Text
- View/download PDF
18. Evaluation of Cell Wall Chemistry of Della and Its Mutant Sweet Sorghum Stalks.
- Author
-
Mengistie E, Alayat AM, Sotoudehnia F, Bokros N, DeBolt S, and McDonald AG
- Subjects
- Cell Wall, Gas Chromatography-Mass Spectrometry, Lignin, Magnetic Resonance Spectroscopy, Sorghum
- Abstract
The cell wall compositional (lignin and polysaccharides) variation of two sweet sorghum varieties, Della (D) and its variant REDforGREEN (RG), was evaluated at internodes (IN) and nodes (N) using high-performance liquid chromatography (HPLC), pyrolysis-gas chromatography-mass spectrometry (Py-GCMS), X-ray diffraction (XRD), and two-dimensional (2D)
1 H-13 C nuclear magnetic resonance (NMR). The stalks were grown in 2018 (D1 and RG1) and 2019 (D2 and RG2) seasons. In RG1, Klason lignin reductions by 16-44 and 2-26% were detected in IN and N, respectively. The analyses also revealed that lignin from the sorghum stalks was enriched in guaiacyl units and the syringyl/guaiacyl ratio was increased in RG1 and RG2, respectively, by 96% and more than 2-fold at IN and 61 and 23% at N. The glucan content was reduced by 23-27% for RG1 and by 17-22% for RG2 at internodes. Structural variations due to changes in both cellulose- and hemicellulose-based sugars were detected. The nonacylated and γ-acylated β-O-4 linkages were the main interunit linkages detected in lignin. These results indicate compositional variation of stalks due to the RG variation, and the growing season could influence their mechanical and lodging behavior.- Published
- 2022
- Full Text
- View/download PDF
19. O-Glycologue: A Formal-Language-Based Generator of O-Glycosylation Networks.
- Author
-
McDonald AG and Davey GP
- Subjects
- Humans, Language, Oligosaccharides, Polysaccharides, Software, Glycosylation
- Abstract
The web application O-Glycologue provides an online simulation of the biosynthetic enzymes of O-linked glycosylation, using a knowledge-based system described previously. Glycans can be imported in GlycoCT condensed format, or else as IUPAC condensed names, and passed as substrates to the enzymes, which are modeled as regular-expression-based substitutions on strings. The resulting networks of reactions can be exported as SBML. The effects of knocking out different sets of enzyme activities can be compared. A method is provided for predicting the enzymes required to produce a given substrate, using an O-glycan from human gastric mucin as an example. The system has been adapted to other systems of glycosylation enzymes, and an application to ganglioside oligosaccharide synthesis is demonstrated. O-Glycologue is available at https://glycologue.org/o/ ., (© 2022. Springer Science+Business Media, LLC, part of Springer Nature.)
- Published
- 2022
- Full Text
- View/download PDF
20. Parameter Reliability and Understanding Enzyme Function.
- Author
-
McDonald AG and Tipton KF
- Subjects
- Algorithms, Enzymes chemistry, Models, Chemical
- Abstract
Knowledge of the Michaelis-Menten parameters and their meaning in different circumstances is an essential prerequisite to understanding enzyme function and behaviour. The published literature contains an abundance of values reported for many enzymes. The problem concerns assessing the appropriateness and validity of such material for the purpose to which it is to be applied. This review considers the evaluation of such data with particular emphasis on the assessment of its fitness for purpose.
- Published
- 2022
- Full Text
- View/download PDF
21. Airy light-sheet Raman imaging.
- Author
-
Subedi NR, Yaraghi S, Jung PS, Kukal G, McDonald AG, Christodoulides DN, and Vasdekis AE
- Subjects
- Dimethylpolysiloxanes, Microscopy, Fluorescence methods, Image Enhancement methods, Lighting methods, Microscopy methods, Spectrum Analysis, Raman methods
- Abstract
Light-sheet fluorescence microscopy has greatly improved the speed and overall photostability of optically sectioning cellular and multi-cellular specimens. Similar gains have also been conferred by light-sheet Raman imaging; these schemes, however, rely on diffraction limited Gaussian beams that hinder the uniformity and size of the imaging field-of-view, and, as such, the resulting throughput rates. Here, we demonstrate that a digitally scanned Airy beam increases the Raman imaging throughput rates by more than an order of magnitude than conventional diffraction-limited beams. Overall, this, spectrometer-less, approach enabled 3D imaging of microparticles with high contrast and 1 µm axial resolution at 300 msec integration times per plane and orders of magnitude lower irradiation density than coherent Raman imaging schemes. We detail the apparatus and its performance, as well as its compatibility with fluorescence light-sheet and quantitative-phase imaging towards rapid and low phototoxicity multimodal imaging.
- Published
- 2021
- Full Text
- View/download PDF
22. Fatal systemic (paradoxical) air embolism diagnosed by postmortem funduscopy.
- Author
-
Bradley LM, McDonald AG, and Lantz PE
- Subjects
- Brain pathology, Humans, Infant, Pneumoperitoneum diagnostic imaging, Retina diagnostic imaging, Retinal Hemorrhage diagnostic imaging, Rib Fractures diagnostic imaging, Skull diagnostic imaging, Subcutaneous Emphysema diagnostic imaging, Child Abuse, Embolism, Air diagnostic imaging, Embolism, Air pathology, Ophthalmoscopy
- Abstract
Air embolism is often unrecognized and underreported. Published case reports or case series describe only rare fundal examinations of retinal air emboli (RAE)-a distinctive sign of systemic air embolism. We report an infant, found unresponsive at home, who died in the emergency department after unsuccessful resuscitative efforts. Before the autopsy, diagnostic RAE were recognized and imaged during postmortem funduscopy. Postmortem radiography and an autopsy confirmed systemic (paradoxical) air embolism due to inflicted abdominal and thoracic blunt force injuries. While a few descriptions and illustrations of RAE occur in case reports, we found no published photographic images of RAE in infants, children, or adults. This case report describes and photographically documents classic RAE associated with fatal systemic (paradoxical) air embolism. Complementing postmortem radiography and judicious autopsy techniques, the detection of RAE can aid pathologists in diagnosing systemic air embolism., (© 2021 American Academy of Forensic Sciences.)
- Published
- 2021
- Full Text
- View/download PDF
23. Kinetics modeling, thermodynamics and thermal performance assessments of pyrolytic decomposition of Moringa oleifera husk and Delonix regia pod.
- Author
-
Balogun AO, Adeleke AA, Ikubanni PP, Adegoke SO, Alayat AM, and McDonald AG
- Abstract
A non-isothermal decomposition of Moringa oleifera husk and Delonix regia seed pod was carried out in an N
2 pyrolytic condition with the primary objective of undertaking the kinetics modeling, thermodynamics and thermal performance analyses of the identified samples. Three different isoconversional models, namely, differential Friedman, Flynn-Wall-Ozawa, and Starink techniques were utilized for the deduction of the kinetics data. The thermodynamic parameters were deduced from the kinetic data based on a first-order chemical reaction model. In the kinetics study, a strong correlation (R2 > 0.9) was observed throughout the conversion range for all the kinetic models. The activation energy profiles showed two distinctive regions. In the first region, the average activation energy values were relatively higher-a typical example is in the Flynn-Wall-Ozawa technique-MH (199 kJ/mol) and RP (194 kJ/mol), while in the second region, MH (292 kJ/mol) and RP (234 kJ/mol). It was also demonstrated that the thermal process for the samples experienced endothermic reactions thought the conversion range. In summary, both the kinetic and thermodynamic parameters vary significantly with conversion-underscoring the complexity associated with the thermal conversion of lignocellulosic biomass samples.- Published
- 2021
- Full Text
- View/download PDF
24. Preparation and Characterization of Biobased Lignin-Co-Polyester/Amide Thermoplastics.
- Author
-
Young EL and McDonald AG
- Subjects
- Chemical Phenomena, Molecular Structure, Polymerization, Spectrometry, Mass, Electrospray Ionization, Spectroscopy, Fourier Transform Infrared, Temperature, Tensile Strength, Thermogravimetry, X-Ray Diffraction, Amides chemistry, Lignin chemistry, Plastics chemistry, Polyesters chemistry
- Abstract
More than 23 million tonnes of lignin are produced annually in the US from wood pulping and 98% of this lignin is burnt. Therefore, creating products from lignin, such as plastics, offers an approach for obtaining sustainable materials in a circular economy. Lignin-based copolymers were synthesized using a single pot, solvent free, melt condensation reaction. The synthesis occurred in two stages. In the first stage, a biobased prepolymer consisting of butanediol (BD, 0.8-1 molar content) and a diacid (succinic (SA), adipic (AA) and suberic acids (SuA), with varying amounts of diaminobutane (DAB, 0-0.2 molar content) was heated under vacuum and monitored by Fourier transform infra-red (FTIR) spectroscopy and electrospray ionization-mass spectrometry (ESI-MS). In the second stage, prepolymer was mixed with a softwood kraft lignin (0-50 wt.%) and further reacted under vacuum at elevated temperature. Progression of the polymerization reaction was monitored using FTIR spectroscopy. The lignin-copolyester/amide properties were characterized using tensile testing, X-ray diffraction (XRD), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. Lignin co-polymer tensile (strength 0.1-2.1 MPa and modulus 2 to 338 MPa) properties were found to be influenced by the diacid chain length, lignin, and DAB contents. The lignin-copolymers were shown to be semi-crystalline polymer and have thermoplastic behavior. The SA based copolyesters/amides were relatively stiff and brittle materials while the AA based copolyesters/amides were flexible and the SuA based copolyesters/amides fell in-between. Additionally, > 30 wt.% lignin the lignin- copolyesters/amides did not exhibit melt behavior. Lignin-co-polyester/amides can be generated using green synthesis methods from biobased building blocks. The lignin- copolyesters/amides properties could be tuned based on the lignin content, DAB content and diacid chain length. This approach shows that undervalued lignin can be used in as a macromonomer in producing thermoplastic materials.
- Published
- 2021
- Full Text
- View/download PDF
25. Simulating the enzymes of ganglioside biosynthesis with Glycologue.
- Author
-
McDonald AG and Davey GP
- Abstract
Gangliosides are an important class of sialylated glycosphingolipids linked to ceramide that are a component of the mammalian cell surface, especially those of the central nervous system, where they function in intercellular recognition and communication. We describe an in silico method for determining the metabolic pathways leading to the most common gangliosides, based on the known enzymes of their biosynthesis. A network of 41 glycolipids is produced by the actions of the 10 enzymes included in the model. The different ganglioside nomenclature systems in common use are compared and a systematic variant of the widely used Svennerholm nomenclature is described. Knockouts of specific enzyme activities are used to simulate congenital defects in ganglioside biosynthesis, and altered ganglioside status in cancer, and the effects on network structure are predicted. The simulator is available at the Glycologue website, https://glycologue.org/., (Copyright © 2021, McDonald and Davey.)
- Published
- 2021
- Full Text
- View/download PDF
26. Synergistic effects of processing parameters on the biochemical and physical properties of tofu made from yellow field pea ( Pisum sativum ), as determined by response surface methodology.
- Author
-
DePalma K, Smith B, and McDonald AG
- Abstract
Peas are an underutilized crop that do not require allergen labeling and are rarely genetically modified. Peas contain less protein than soy and vary in protein composition. Because peas contain more starch than soy and less lipids, an alternative procedure for pea tofu production needs to be developed to prevent excessive starch gelatinization while promoting curd development. To accomplish this, a response surface model design was utilized to determine optimal oil addition, cook time, and salt concentration. Treatment ranges were from 0.0% to 4.2% for oil addition, 60-134 min for cook time, and 5.0%-9.2% for MgCl
2 addition. Treatments had varying effects on tofu texture. Cook time was directly proportional to the hardness and could be used to match the soft, firm, and extra firm texture targets of conventional soy tofu. Protein secondary structure was not related to gel strength, indicating a system with synergies between multiple components other than protein. This research will help satisfy the growing demand for alternatives to soy-based foods., (© 2021 The Authors. Food Science & Nutrition published by Wiley Periodicals LLC.)- Published
- 2021
- Full Text
- View/download PDF
27. Degradation of thymic humoral factor γ2 in human, rat and mouse blood: An experimental and theoretical study.
- Author
-
Martignoni M, Benedetti M, Davey GP, Tipton KF, and McDonald AG
- Subjects
- Aminopeptidases, Animals, Dipeptides chemistry, Half-Life, Humans, Kinetics, Male, Mice, Models, Animal, Models, Theoretical, Neprilysin metabolism, Oligopeptides chemistry, Peptide Hydrolases, Peptidyl-Dipeptidase A metabolism, Rats, Rats, Wistar, Oligopeptides blood, Oligopeptides metabolism
- Abstract
The degradation of the immunomodulatory octapeptide, thymic humoral factor γ2 (THF-γ2, thymoctonan) has been studied in whole blood samples from human, rat and mouse. The peptide, Leu-Glu-Asp-Gly-Pro-Lys-Phe-Leu, was shown to be rapidly degraded by peptidases. The half-life of the intact peptide was less than 6 min at 37 °C in blood from the three species tested. The main fragments formed from THF-γ2 were found to be Glu-Asp-Gly-Pro-Lys-Phe-Leu (2-8), Asp-Gly-Pro-Lys-Phe-Leu (3-8) and Glu-Asp-Gly-Pro-Lys (2-6) in human and in rat blood and 2-8 and 2-6 in mouse blood. Analysis of the time course of degradation revealed a sequential removal of single amino acids from the N-terminus (aminopeptidase activities) in a process that was apparently unable to cleave the Gly-Pro bond (positions 4-5 in the peptide) together with an independent cleavage of the Lys-Phe bond (positions 6-7 in the peptide) to release the dipeptide Phe-Leu. This behaviour and the effects of inhibitors showed the involvement of metallo-exopeptidases in the N-terminal digestion and a phosphoramidon-sensitive metallo-endopeptidase in the cleavage of the Lys-Phe bond. The degradation patterns in human blood were modelled in terms of the competing pathways involved approximating to first-order kinetics, and an analytical solution obtained via the method of Laplace Transforms. The half-life of THF degradation in whole rat blood sample was found to be significantly lower than in human or mouse., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 The Author(s). Published by Elsevier B.V. All rights reserved.)
- Published
- 2020
- Full Text
- View/download PDF
28. Molecular and clinicopathologic characterization of intravenous leiomyomatosis.
- Author
-
Ordulu Z, Chai H, Peng G, McDonald AG, De Nictolis M, Garcia-Fernandez E, Hardisson D, Prat J, Li P, Hui P, Oliva E, and Buza N
- Subjects
- Adult, Aged, Aged, 80 and over, Comparative Genomic Hybridization, Cyclin D1 genetics, Cyclin D1 metabolism, Cyclin-Dependent Kinase Inhibitor p16 genetics, Cyclin-Dependent Kinase Inhibitor p16 metabolism, Female, Humans, Leiomyomatosis metabolism, Leiomyomatosis pathology, Middle Aged, Phosphorylation, Uterine Neoplasms metabolism, Uterine Neoplasms pathology, Uterus metabolism, Leiomyomatosis genetics, Uterine Neoplasms genetics, Uterus pathology
- Abstract
Intravenous leiomyomatosis (IVL) is an unusual uterine smooth muscle proliferation that can be associated with aggressive clinical behavior despite a histologically benign appearance. It has some overlapping molecular characteristics with both uterine leiomyoma and leiomyosarcoma based on limited genetic data. In this study, we assessed the clinical and morphological characteristics of 28 IVL and their correlation with molecular features and protein expression, using array comparative genomic hybridization (aCGH) and Cyclin D1, p16, phosphorylated-Rb, SMARCB1, SOX10, CAIX, SDHB and FH immunohistochemistry. The most common morphologies were cellular (n = 15), usual (n = 11), and vascular (n = 5; including 3 cellular IVL showing both vascular and cellular features). Among the immunohistochemical findings, the most striking was that all IVL showed differential expression of either p16 or Cyclin D1 in comparison to surrounding nonneoplastic tissue. Cytoplasmic phosphorylated-Rb was present in all but one IVL with hyalinization. SMARCB1, FH, and SDHB were retained; S0X10 and CAIX were not expressed. The most common genetic alterations involved 1p (39%), 22q (36%), 2q (29%), 1q (25%), 13q (21%), and 14q (21%). Hierarchical clustering analysis of recurrent aberrations revealed three molecular groups: Groups 1 (29%) and 2 (18%) with associated del(22q), and Group 3 (18%) with del(10q). The remaining IVL had nonspecific or no alterations by aCGH. Genomic index scores were calculated for all cases and showed no significant difference between the 14 IVL associated with aggressive clinical behavior (extrauterine extension or recurrence) and those without (median scores 5.15 vs 3.5). Among the 5 IVL associated with recurrence, 4 had a vascular morphology and 3 had alterations of 8q. Recurrent chromosome alterations detected herein overlap with those observed in the spectrum of uterine smooth muscle tumors and involve genes implicated in mesenchymal tumors at different sites with distinct morphological features.
- Published
- 2020
- Full Text
- View/download PDF
29. A Fatal Infection With Subtle and Nonspecific Signs and Symptoms: Answer.
- Author
-
Silloca Cabana EO and McDonald AG
- Subjects
- Fatal Outcome, Herpesvirus 1, Human, Humans, Infant, Newborn, Male, Herpes Simplex pathology, Herpes Simplex transmission, Infectious Disease Transmission, Vertical
- Published
- 2020
- Full Text
- View/download PDF
30. A Fatal Infection With Subtle and Nonspecific Signs and Symptoms in a Neonate: Challenge.
- Author
-
Silloca Cabana EO and McDonald AG
- Published
- 2020
- Full Text
- View/download PDF
31. Properties of pellets of torrefied U.S. waste blends.
- Author
-
Zinchik S, Xu Z, Kolapkar SS, Bar-Ziv E, and McDonald AG
- Subjects
- Biomass, Plastics, Temperature, Water, Hot Temperature, Solid Waste
- Abstract
With the continued growing U.S. population, solid waste generation will increase, which will lead to undesired and significant growth in landfilling. Thermal treatment can turn these high calorific value wastes into fuels that can be used in small-to-large power plants. This article focuses on using blends with 40% plastic and 60% fiber wastes and converting them into densified solid fuel by torrefaction and extrusion. The material was torrefied at 300 °C to obtain torrefied samples with different mass losses, ranging from 0% to a maximum of 51%. The torrefaction results showed a clear synergy between plastics and fibers. The torrefied material was then extruded into 9 mm diameter rods and the products were characterized by molecular functional group analysis, thermomechanical analysis, dynamic mechanical analysis, dynamic rheological measurement, density measurement, flexural testing, water absorption test, size distribution measurement, heat content test, and combustion test. The fiber content in the material decreased as mass loss increased, and the process reduced significantly the variability of the material. The heat content increased as the mass loss increased. The plastic in the feedstock acted as a process enabler as it imparted properties like bindability, water resistance, high heat content, and increased degradation reaction rate., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)
- Published
- 2020
- Full Text
- View/download PDF
32. Evaluation of the Mechanical, Thermal and Rheological Properties of Recycled Polyolefins Rice-hull Composites.
- Author
-
Orji BO and McDonald AG
- Abstract
Understanding the properties and flow characteristics of recycled polyolefins in rice hull composite blends is of importance to facilitate process optimization whilst promoting sustainability. The influence of milled rice hull particle size (<0.5 mm and <1 mm) on properties of recycled polyolefins composites was studied with major focus on recycled high-density polyethylene (rHDPE) and polypropylene (rPP) together with added maleated polymer coupling agents. Composites were compounded/extruded using a twin-screw extruder and the thermal, mechanical, and physical properties were analyzed as well as their melt flow, dynamic. and capillary rheology tests. The incorporation of the <0.5 mm rice-hulls particles enhanced the composite properties of viscosity, flexural strength, moduli, water absorption, and thermal stability for both polyolefins with rHDPE composites showing more reliable properties as compared to rPP.
- Published
- 2020
- Full Text
- View/download PDF
33. 6-Hydroxydopamine: a far from simple neurotoxin.
- Author
-
Varešlija D, Tipton KF, Davey GP, and McDonald AG
- Subjects
- Animals, Humans, Neurotoxins toxicity, Oxidopamine toxicity, Disease Models, Animal, Neurotoxins pharmacology, Oxidopamine pharmacology, Parkinson Disease
- Abstract
6-Hydroxydopamine (6-OHDA), which is a neurotoxin that selectively destroys catecholaminergic nerves in sympathetically innervated tissues, has been used to provide a model of Parkinson's disease in experimental animals. It is rapidly autoxidised to yield potentially toxic products and reactive oxygen species. Its ability to release Fe(II) from protein storage sites also results in the formation of hROS. This account will consider how this family of toxic products may contribute to the observed effects of 6-OHDA.
- Published
- 2020
- Full Text
- View/download PDF
34. Effect of Processing Conditions, Biochemical Properties, and Microstructure on Tofu Production from Yellow Field Peas (Pisum sativum).
- Author
-
DePalma K, Smith B, and McDonald AG
- Subjects
- Cooking, Hardness, Hot Temperature, Hydrophobic and Hydrophilic Interactions, Food Handling methods, Pisum sativum chemistry, Plant Preparations chemistry
- Abstract
Tofu, made by coagulating soy milk, is a nutritious food originating in China and is widely consumed globally. Due to allergenicity and consumer perceptions of genetically modified organisms, consumer demand for soy alternatives is increasing. In this study, tofu was made from yellow split peas (Pisum sativum). Effects of pasteurization, fat addition, and curd disruption followed by repressing were studied. Here, disruption was not a chemical disruption, rather a physical disruption of protein curds. Pasteurization alone led to increased uptake of water and nonviable tofus. Disrupted samples became firmer with pasteurization. Texture profile analysis indicated that disruption followed by pasteurization improved hardness from approximately 175 g force from the control, to approximately 325 g force for disrupted + pasteurizated samples without fat addition. A similar trend was observed for samples with fat added, where hardness increased from approximately 50 g force to approximately 75 g force. Fourier-transform infrared spectroscopy of the amide I region showed that an increase of β-sheet structures led to increased hardness. The shifts in β-sheet structures followed the same trends as surface hydrophobicity. Surface hydrophobicity decreased with pasteurization and increased with disruption. Molecular weight analysis showed that shear (from disruption) and heat separately degraded the proteins into smaller polypeptides exposing hydrophobic interiors. Changes to biochemical parameters, such as protein secondary structure and exposure of protein hydrophobic regions, allowed for tofu to be made from yellow field peas. PRACTICAL APPLICATION: This study provides critical information and a means to produce pea-based soy-free tofu., (© 2019 Institute of Food Technologists®.)
- Published
- 2019
- Full Text
- View/download PDF
35. Alumina Coated Silica Nanosprings (NS) Support Based Cobalt Catalysts for Liquid Hydrocarbon Fuel Production From Syngas.
- Author
-
Alayat A, Echeverria E, Sotoudehniakarani F, Mcllroy DN, and McDonald AG
- Abstract
The effects of Al
2 O3 coating on the performance of silica nanospring (NS) supported Co catalysts for Fischer-Tropsch synthesis (FTS) were evaluated in a quartz fixed-bed microreactor. The Co/NS-Al2 O3 catalysts were synthesized by coating the Co/NS and NS with Al2 O3 by an alkoxide-based sol-gel method (NS-Al-A and NS-Al-B, respectively) and then by decorating them with Co. Co deposition was via an impregnation method. Catalysts were characterized before the FTS reaction by the Brunauer-Emmett-Teller (BET) method, X-ray diffraction, transmission electron microscopy, temperature programmed reduction, X-ray photoelectron spectroscopy, differential thermal analysis and thermogravimetric analysis in order to find correlations between physico-chemical properties of catalysts and catalytic performance. The products of the FTS were trapped and analyzed by GC-TCD and GC-MS to determine the CO conversion and reaction selectivity. The Al2 O3 coated NS catalyst had a significant affect in FTS activity and selectivity in both Co/NS-Al2 O3 catalysts. A high CO conversion (82.4%) and Σ > C6 (86.3%) yield were obtained on the Co/NS-Al-B catalyst, whereas the CO conversion was 62.8% and Σ > C6 was 58.5% on the Co/NS-Al-A catalyst under the same FTS experimental condition. The Co/NS-Al-A catalyst yielded the aromatic selectivity of 10.2% and oxygenated compounds.- Published
- 2019
- Full Text
- View/download PDF
36. A mechanism for bistability in glycosylation.
- Author
-
McDonald AG, Tipton KF, and Davey GP
- Subjects
- Biophysical Phenomena physiology, Catalysis, Enzyme Activation, Feedback, Physiological physiology, Galactosyltransferases metabolism, Glycosylation, Glycosyltransferases physiology, Humans, Kinetics, Substrate Specificity physiology, Glycosyltransferases metabolism, Glycosyltransferases pharmacokinetics
- Abstract
Glycosyltransferases are a class of enzymes that catalyse the posttranslational modification of proteins to produce a large number of glycoconjugate acceptors from a limited number of nucleotide-sugar donors. The products of one glycosyltransferase can be the substrates of several other enzymes, causing a combinatorial explosion in the number of possible glycan products. The kinetic behaviour of systems where multiple acceptor substrates compete for a single enzyme is presented, and the case in which high concentrations of an acceptor substrate are inhibitory as a result of abortive complex formation, is shown to result in non-Michaelian kinetics that can lead to bistability in an open system. A kinetic mechanism is proposed that is consistent with the available experimental evidence and provides a possible explanation for conflicting observations on the β-1,4-galactosyltransferases. Abrupt switching between steady states in networks of glycosyltransferase-catalysed reactions may account for the observed changes in glycosyl-epitopes in cancer cells., Competing Interests: The authors have declared that no competing interests exist.
- Published
- 2018
- Full Text
- View/download PDF
37. Neuropharmacological profile and chemical analysis of fresh rhizome essential oil of Curcuma longa (turmeric) cultivated in Southwest Nigeria.
- Author
-
Oyemitan IA, Elusiyan CA, Onifade AO, Akanmu MA, Oyedeji AO, and McDonald AG
- Abstract
Background: Curcuma longa (turmeric) is commonly used as spice and also used to treat fever, cough and febrile convulsions in Nigeria. This study determined the chemical composition of the essential oil of C. longa and evaluated its neuropharmacological activity in mice., Methods: Essential oil of C. longa (EOCL) fresh rhizome was obtained by hydrodistillation and its chemical composition determined by GC-MS. Acute toxicity (LD
50 ) profile of the essential oil was determined orally (p.o.) and intraperitoneally (i.p.); and the EOCL (50-200 mg/kg, i.p.) was evaluated for its behavioural, anxiolytic, sedative and anticonvulsant activities using appropriate models in Albino mice (Vom Strain, Jos, Nigeria)., Results: Analysis of the oil showed the presence of 23 compounds with turmerone (35.9%) being the major component. The LD50 values obtained for the mice were 2154 mg/kg, p.o., and 693 mg/kg, i.p. The EOCL (50-200 mg/kg, i.p.) caused significant (p < 0.01) inhibition of rearing {F(4,20) = 9} and locomotor {F(3,16) = 42} activity; decreased head dips in hole board {F(4,20) = 4}; increased the time spent in the open arms of the elevated pus maze {F(4,20) = 9}; prolonged total sleeping time {F(4,20) = 21} induced by ketamine injection, and protected mice against pentylenetetrazol-induced convulsions., Conclusion: The major component of the essential oil of this C. longa species was turmerone; the oil was slightly toxic orally but moderately toxic intraperitoneally in mice; exhibited significant anxiolytic, sedative and anticonvulsant activities in mice.- Published
- 2017
- Full Text
- View/download PDF
38. Metabolic flux control in glycosylation.
- Author
-
McDonald AG, Hayes JM, and Davey GP
- Subjects
- Animals, Enzymes metabolism, Humans, Models, Biological, Glycosylation, Metabolic Flux Analysis methods
- Abstract
Glycosylation is a common post-translational protein modification, in which glycans are built onto proteins through the sequential addition of monosaccharide units, in reactions catalysed by glycosyltransferases. Glycosylation influences the physicochemical and biological properties of proteins, with subsequent effects on subcellular and extracellular protein trafficking, cell-cell recognition, and ligand-receptor interactions. Glycan structures can be complex, as is the regulation of their biosynthesis, and it is only recently that the systems biology of metabolic flux control and glycosyltransferase networks has become a study in its own right. We review various models of glycosylation that have been proposed to date, based on current knowledge of Golgi structure and function, and consider how metabolic flux through glycosyltransferase networks regulates glycosylation events in the cell., (Copyright © 2016 Elsevier Ltd. All rights reserved.)
- Published
- 2016
- Full Text
- View/download PDF
39. Analysis of microbial community variation during the mixed culture fermentation of agricultural peel wastes to produce lactic acid.
- Author
-
Liang S, Gliniewicz K, Gerritsen AT, and McDonald AG
- Subjects
- Acetic Acid metabolism, Agriculture methods, Bioreactors microbiology, Citrus sinensis, Lactic Acid metabolism, Lactobacillus genetics, Lactobacillus metabolism, Microbial Consortia genetics, Musa, RNA, Ribosomal, 16S genetics, Solanum tuberosum, Biotechnology methods, Fermentation, Industrial Waste, Lactic Acid biosynthesis, Microbial Consortia physiology
- Abstract
Mixed cultures fermentation can be used to convert organic wastes into various chemicals and fuels. This study examined the fermentation performance of four batch reactors fed with different agricultural (orange, banana, and potato (mechanical and steam)) peel wastes using mixed cultures, and monitored the interval variation of reactor microbial communities with 16S rRNA genes using Illumina sequencing. All four reactors produced similar chemical profile with lactic acid (LA) as dominant compound. Acetic acid and ethanol were also observed with small fractions. The Illumina sequencing results revealed the diversity of microbial community decreased during fermentation and a community of largely lactic acid producing bacteria dominated by species of Lactobacillus developed., (Copyright © 2016 Elsevier Ltd. All rights reserved.)
- Published
- 2016
- Full Text
- View/download PDF
40. A Review on Grafting of Biofibers for Biocomposites.
- Author
-
Wei L and McDonald AG
- Abstract
A recent increase in the use of biofibers as low-cost and renewable reinforcement for the polymer biocomposites has been seen globally. Biofibers are classified into: lignocellulosic fibers ( i.e. , cellulose, wood and natural fibers), nanocellulose ( i.e. , cellulose nanocrystals and cellulose nanofibrils), and bacterial cellulose, while polymer matrix materials can be petroleum based or bio-based. Green biocomposites can be produced using both biobased fibers and polymers. Incompatibility between the hydrophilic biofibers and hydrophobic polymer matrix can cause performance failure of resulting biocomposites. Diverse efforts have focused on the modification of biofibers in order to improve the performances of biocomposites. "Grafting" copolymerization strategy can render the advantages of biofiber and impart polymer properties onto it and the performance of biocomposites can be tuned through changing grafting parameters. This review presents a short overview of various "grafting" methods which can be directly or potentially employed to enhance the interaction between biofibers and a polymer matrix for biocomposites. Major grafting techniques, including ring opening polymerization, grafting via coupling agent and free radical induced grafting, have been discussed. Improved properties such as mechanical, thermal, and water resistance have provided grafted biocomposites with new opportunities for applications in specific industries.
- Published
- 2016
- Full Text
- View/download PDF
41. A Knowledge-Based System for Display and Prediction of O-Glycosylation Network Behaviour in Response to Enzyme Knockouts.
- Author
-
McDonald AG, Tipton KF, and Davey GP
- Subjects
- Animals, CHO Cells, Computational Biology, Computer Simulation, Cricetulus, Gene Knockout Techniques, Genetic Engineering, Glycosylation, Glycosyltransferases deficiency, Glycosyltransferases genetics, Glycosyltransferases metabolism, Humans, Metabolic Networks and Pathways genetics, Models, Biological, Mucins chemistry, Polysaccharides chemistry, Polysaccharides metabolism, Terminology as Topic, Knowledge Bases, Mucins metabolism, Protein Processing, Post-Translational
- Abstract
O-linked glycosylation is an important post-translational modification of mucin-type protein, changes to which are important biomarkers of cancer. For this study of the enzymes of O-glycosylation, we developed a shorthand notation for representing GalNAc-linked oligosaccharides, a method for their graphical interpretation, and a pattern-matching algorithm that generates networks of enzyme-catalysed reactions. Software for generating glycans from the enzyme activities is presented, and is also available online. The degree distributions of the resulting enzyme-reaction networks were found to be Poisson in nature. Simple graph-theoretic measures were used to characterise the resulting reaction networks. From a study of in-silico single-enzyme knockouts of each of 25 enzymes known to be involved in mucin O-glycan biosynthesis, six of them, β-1,4-galactosyltransferase (β4Gal-T4), four glycosyltransferases and one sulfotransferase, play the dominant role in determining O-glycan heterogeneity. In the absence of β4Gal-T4, all Lewis X, sialyl-Lewis X, Lewis Y and Sda/Cad glycoforms were eliminated, in contrast to knockouts of the N-acetylglucosaminyltransferases, which did not affect the relative abundances of O-glycans expressing these epitopes. A set of 244 experimentally determined mucin-type O-glycans obtained from the literature was used to validate the method, which was able to predict up to 98% of the most common structures obtained from human and engineered CHO cell glycoforms.
- Published
- 2016
- Full Text
- View/download PDF
42. Mass spectrometry data for in vitro protein profiles in early and late stages of Douglas-fir xylogenesis.
- Author
-
Dziedzic JA and McDonald AG
- Abstract
A Douglas-fir tissue culture system was developed [1] that could be induced to differentiate into tracheary elements (fibers) making it possible to monitor xylogenesis in vitro by a proteomics approach. Two proteomes, one from an early and one from a late stage of fiber differentiation process were analyzed and compared. Obtained mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium (http://proteomecentral.proteomexchange.org) via the PRIDE partner repository [2] with the dataset identifiers PXD001484 and DOI:10.6019/ PXD001484 [3].
- Published
- 2016
- Full Text
- View/download PDF
43. Anaerobic digestion of pre-fermented potato peel wastes for methane production.
- Author
-
Liang S and McDonald AG
- Subjects
- Anaerobiosis, Biodegradation, Environmental, Fatty Acids, Volatile analysis, Fatty Acids, Volatile metabolism, Fermentation, Methane metabolism, Waste Management, Biofuels analysis, Garbage, Lactic Acid metabolism, Methane analysis, Solanum tuberosum chemistry
- Abstract
This study investigated the feasibility of anaerobic digestion (AD) of potato peel waste (PPW) and its lactic acid fermentation residue (PPW-FR) for methane (CH4) production. The experimental results showed that about 60-70% CH4 content was obtained. The digester using PPW-FR as feedstock exhibited better performance and produced a highest cumulative CH4 production of 273 L/kg VS fed, followed by 239 L/kg VS fed using PPW under the same conditions. However, with increasing solid loadings of PPW-FR feedstock from 6.4% to 9.1%, the CH4 production was inhibited. The generation, accumulation, and degradation of volatile fatty acids (VFAs) in digesters were also investigated in this research., (Copyright © 2015 Elsevier Ltd. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
44. Valorization of residual bacterial biomass waste after polyhydroxyalkanoate isolation by hydrothermal treatment.
- Author
-
Wei L, Liang S, Coats ER, and McDonald AG
- Subjects
- 3-Hydroxybutyric Acid, Biofuels economics, Biomass, Carbohydrates analysis, Hydroxybutyrates, Industrial Waste economics, Lignin analysis, Pentanoic Acids, Polyhydroxyalkanoates isolation & purification, Biofuels analysis, Hot Temperature, Industrial Waste analysis
- Abstract
Hydrothermal treatment (HTT) was used to convert residual bacterial biomass (RBB), recovered from poly(3-hydroxybutyrate-co-3-hydroxyvalerate) production, into valuable bioproducts. The effect of processing temperatures (150, 200, and 250°C) on the bioproducts (water-solubles (WSs), bio-oil, insoluble residue, and gas) was investigated. The yields of bio-oil and gas were higher at higher temperatures. The maximum WS content (28 wt%) was obtained at 200°C. GCMS analysis showed higher content of aromatics and N-containing compounds with increasing temperature. ESI-MS revealed chemical compounds (e.g. protein, carbohydrate, lipids, and lignin) associated with RBB are fragmented into smaller molecules (monomers) at higher HTT temperatures. The WS fraction contained totally 838, 889 and 886mg/g acids and 160, 31 and 21 mg/g carbohydrate for HTT at 150, 200, and 250°C, respectively. The solid residues contain unconverted compounds, especially after HTT at 150°C. The WS products (acids and carbohydrates) could be used directly for PHA biosynthesis., (Copyright © 2015 Elsevier Ltd. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
45. Lactic acid production from potato peel waste by anaerobic sequencing batch fermentation using undefined mixed culture.
- Author
-
Liang S, McDonald AG, and Coats ER
- Subjects
- Anaerobiosis, Bioreactors, Fermentation, Food, Lactic Acid metabolism, Solanum tuberosum chemistry, Solid Waste analysis, Waste Management methods
- Abstract
Lactic acid (LA) is a necessary industrial feedstock for producing the bioplastic, polylactic acid (PLA), which is currently produced by pure culture fermentation of food carbohydrates. This work presents an alternative to produce LA from potato peel waste (PPW) by anaerobic fermentation in a sequencing batch reactor (SBR) inoculated with undefined mixed culture from a municipal wastewater treatment plant. A statistical design of experiments approach was employed using set of 0.8L SBRs using gelatinized PPW at a solids content range from 30 to 50 g L(-1), solids retention time of 2-4 days for yield and productivity optimization. The maximum LA production yield of 0.25 g g(-1) PPW and highest productivity of 125 mg g(-1) d(-1) were achieved. A scale-up SBR trial using neat gelatinized PPW (at 80 g L(-1) solids content) at the 3 L scale was employed and the highest LA yield of 0.14 g g(-1) PPW and a productivity of 138 mg g(-1) d(-1) were achieved with a 1 d SRT., (Copyright © 2015 Elsevier Ltd. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
46. Lignin-Based Triple Shape Memory Polymers.
- Author
-
Sivasankarapillai G, Li H, and McDonald AG
- Subjects
- Lignin chemistry, Nylons chemical synthesis, Nylons chemistry, Polyamines chemical synthesis, Polyamines chemistry, Polyesters chemical synthesis, Polyesters chemistry
- Abstract
Lignin-based triple shape memory polymers comprised of both permanent covalent cross-links and physical cross-links have been synthesized. A mixing phase with poly(ester-amine) and poly(ester-amide) network having two distinct glass transitions was hot mixed with more structurally homogenized methanol soluble lignin fraction by one-pot, two-step method. Triple shape properties arise from the combined effect of the glass transition of polyester copolymers and lignin and the dissociation of self-complementary hydrogen bonding and cross-link density. The percentage of recovery in each stage was investigated and it was proved that the first recovery is related with lignin-poly(ester-amine) rich network and the second recovery stage is related with lignin-poly(ester-amide) rich network. The thermal and mechanical properties of the lignin-copolymer networks were also investigated using differential scanning calorimetry and dynamic mechanical analysis.
- Published
- 2015
- Full Text
- View/download PDF
47. In vitro protein profiles in the early and late stages of Douglas-fir xylogenesis.
- Author
-
Dziedzic JA and McDonald AG
- Subjects
- Electrophoresis, Gel, Two-Dimensional, Plant Proteins chemistry, Plant Proteins metabolism, Proteome chemistry, Proteome metabolism, Pseudotsuga chemistry, Pseudotsuga metabolism, Tissue Culture Techniques, Wood chemistry, Wood metabolism, Plant Proteins analysis, Proteome analysis, Pseudotsuga growth & development, Wood growth & development
- Abstract
The process of wood formation is of great interest to control and manipulate wood quality for economically important gymnosperms. A Douglas-fir tissue culture system was developed that could be induced to differentiate into tracheary elements (fibers) making it possible to monitor xylogenesis in vitro by a proteomics approach. Two proteomes were analyzed and compared, one from an early and one from a late stage of the fiber differentiation process. After 18 weeks in a differentiation-inducing medium, 80% of the callus cells were elongated while 20% showed advanced spiral thickening indicating full wood fiber differentiation. Based on 2D electrophoresis, MS, and data analyses (data are available via ProteomeXchange with identifier PXD001484.), it was shown that in nondifferentiated callus (representing an early stage of development), proteins related to protein metabolism, cellular energy, and primary cell wall metabolism were abundant. By comparison, in cells actively differentiating wood fibers (representing a late stage of development), proteins involved in cell wall polysaccharide biosynthesis predominated together with housekeeping and stress-associated proteins., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2015
- Full Text
- View/download PDF
48. Absence of rickets in infants with fatal abusive head trauma and classic metaphyseal lesions.
- Author
-
Perez-Rossello JM, McDonald AG, Rosenberg AE, Tsai A, and Kleinman PK
- Subjects
- Diagnosis, Differential, Female, Femur, Humans, Infant, Male, Retrospective Studies, Child Abuse diagnosis, Child Abuse mortality, Craniocerebral Trauma diagnosis, Rickets diagnosis
- Abstract
Purpose: To determine if rickets is present in cases of infant homicide with classic metaphyseal lesions (CMLs) and other skeletal injuries., Materials and Methods: This study was exempt from the institutional human subjects board review because all infants were deceased. An archival review (1984-2012) was performed of the radiologic and histopathologic findings of 46 consecutive infant fatalities referred from the state medical examiner's office for the evaluation of possible child abuse. Thirty infants with distal femoral histologic material were identified. Additional inclusion criteria were as follows: (a) The medical examiner determined that the infant had sustained a head injury and that the manner of death was a homicide, (b) at least one CML was evident at skeletal survey, (c) CMLs were confirmed at autopsy, and (d) non-CML fractures were also present. Nine infants (mean age, 3.9 months; age range, 1-9 months) were identified. Two pediatric radiologists independently reviewed the skeletal surveys for rachitic changes at the wrists and knees. A bone and soft tissue pathologist reviewed the distal femoral histologic slices for rickets., Results: There were no radiographic or pathologic features of rickets in the cohort., Conclusion: The findings provide no support for the view that the CML is due to rickets. Rather, they strengthen a robust literature that states that the CML is a traumatic injury commonly encountered in physically abused infants., (RSNA, 2015)
- Published
- 2015
- Full Text
- View/download PDF
49. Grafting of bacterial polyhydroxybutyrate (PHB) onto cellulose via in situ reactive extrusion with dicumyl peroxide.
- Author
-
Wei L, McDonald AG, and Stark NM
- Subjects
- Acetylation, Carbohydrate Conformation, Crystallography, X-Ray, Free Radicals chemistry, Benzyl Compounds chemistry, Cellulose chemistry, Hydroxybutyrates chemistry
- Abstract
Polyhydroxybutyrate (PHB) was grafted onto cellulose fiber by dicumyl peroxide (DCP) radical initiation via in situ reactive extrusion. The yield of the grafted (cellulose-g-PHB) copolymer was recorded and grafting efficiency was found to be dependent on the reaction time and DCP concentration. The grafting mechanism was investigated by electron spin resonance (ESR) analysis and showed the presence of radicals produced by DCP radical initiation. The grafted copolymer structure was determined by nuclear magnetic resonance (NMR) spectroscopy. Scanning electronic microscopy (SEM) showed that the cellulose-g-PHB copolymer formed a continuous phase between the surfaces of cellulose and PHB as compared to cellulose-PHB blends. The relative crystallinity of cellulose and PHB were quantified from Fourier transform infrared (FTIR) spectra and X-ray diffraction (XRD) results, while the absolute degree of crystallinity was evaluated by differential scanning calorimetry (DSC). The reduction of crystallinity indicated the grafting reaction occurred not just in the amorphous region but also slightly in crystalline regions of both cellulose and PHB. The smaller crystal sizes suggested the brittleness of PHB was decreased. Thermogravimetric analysis (TGA) showed that the grafted copolymer was stabilized relative to PHB. By varying the reaction parameters the compositions (%PHB and %cellulose) of resultant cellulose-g-PHB copolymer are expected to be manipulated to obtain tunable properties.
- Published
- 2015
- Full Text
- View/download PDF
50. Comparative analysis of microbial community of novel lactic acid fermentation inoculated with different undefined mixed cultures.
- Author
-
Liang S, Gliniewicz K, Mendes-Soares H, Settles ML, Forney LJ, Coats ER, and McDonald AG
- Subjects
- Bacteria genetics, Biodiversity, Biomass, Cities, Lactobacillus metabolism, Phylogeny, RNA, Ribosomal, 16S genetics, Sequence Analysis, RNA, Wastewater microbiology, Water Purification, Bacteria metabolism, Fermentation, Lactic Acid metabolism
- Abstract
Three undefined mixed cultures (activated sludge) from different municipal wastewater treatment plants were used as seeds in a novel lactic acid fermentation process fed with potato peel waste (PPW). Anaerobic sequencing batch fermenters were run under identical conditions to produce predominantly lactic acid. Illumina sequencing was used to examine the 16S rRNA genes of bacteria in the three seeds and fermenters. Results showed that the structure of microbial communities of three seeds were different. All three fermentation products had unique community structures that were dominated (>96%) by species of the genus Lactobacillus, while members of this genus constituted <0.1% in seeds. The species of Lactobacillus sp. differed among the three fermentations. Results of this study suggest the structure of microbial communities in lactic acid fermentation of PPW with undefined mixed cultures were robust and resilient, which provided engineering prospects for the microbial utilization of carbohydrate wastes to produce lactic acid., (Copyright © 2014 Elsevier Ltd. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.