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Huang L, Jansen L, Balavarca Y, Verhoeven RH, Ruurda JP, Van Eycken L, De Schutter H, Johansson J, Lindblad M, Johannesen TB, Zadnik V, Žagar T, Mägi M, Bastiaannet E, Lagarde SM, van de Velde CJ, Schrotz‐King P, Brenner H. Decreasing resection rates for nonmetastatic gastric cancer in Europe and the United States. Clin Transl Med 2020; 10:e203. [PMID: 33135354 PMCID: PMC7586997 DOI: 10.1002/ctm2.203] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 09/12/2020] [Accepted: 09/22/2020] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Resection is the cornerstone of curative treatment for many nonmetastatic gastric cancers (GCs), but the population treatment patterns remains largely unknown. This large international population-based study aimed at investigating the treatment patterns and trends for nonmetastatic GC in Europe and the United States and at exploring factors associated with resection. METHODS Data of patients with microscopically confirmed primary invasive GC without distant metastasis from the national cancer registries of the Netherlands, Belgium, Sweden, Norway, Slovenia, and Estonia and the US Surveillance, Epidemiology, and End Results (SEER)-18 Program were retrieved. Age-standardized treatment rates were computed and trends were evaluated using linear regression. Associations of resection with patient and tumor characteristics were analyzed using multivariable-adjusted log-binomial regression. Analysis was performed in each country respectively without pooling. RESULTS Together 65 707 nonmetastatic GC patients diagnosed in 2003-2016 were analyzed. Age-standardized resection rates significantly decreased over years in all countries (by 4-24%). In 2013-2014, rates varied greatly from 54 to 75%. Patients with increasing ages, cardia cancers, or cancers invading adjacent structure were significantly less frequently resected. Resection was further associated with sex, performance status, comorbidities, tumor histology, tumor size, hospital type, and hospital volume. Association patterns and strengths varied across countries. After multivariable adjustment, resection rates remained decreasing (prevalence ratio = 0.97-0.995 per year), with decreasing trends consistently seen in various subgroups. CONCLUSIONS Nonmetastatic GCs were less frequently resected in Europe and the United States in the early 21st century. Resection rates varied greatly across countries and appeared not to be optimal. Various factors associated with resection were revealed. Our findings can help to identify differences and possibly modifiable places in clinical practice and provide important novel references for designing effective population-based GC management strategies. In Europe and the United States, nonmetastatic gastric cancers were less frequently resected in the early 21st century. Resection rates varied greatly across countries and appeared not optimal. Various factors associated with resection were revealed. Our findings identify differences and possibly modifiable places in clinical practice and provide important novel references for designing effective population-based management strategies.
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Li M, Sun Y, Yang J, de Martel C, Charvat H, Clifford GM, Vaccarella S, Wang L. Time trends and other sources of variation in Helicobacter pylori infection in mainland China: A systematic review and meta-analysis. Helicobacter 2020; 25:e12729. [PMID: 32686261 DOI: 10.1111/hel.12729] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/24/2020] [Accepted: 06/27/2020] [Indexed: 12/17/2022]
Abstract
BACKGROUND Helicobacter pylori (H pylori) is a carcinogen that causes a huge burden of gastric cancer in China. We aimed to evaluate the temporal trends and other sources of variation of H pylori infection in adults from mainland China. MATERIALS AND METHODS For this systematic review and meta-analysis, we searched PubMed, Embase, China National Knowledge Infrastructure, and Wanfang databases for articles published from January 1983 to June 2020. We included studies reporting H pylori prevalence in adults and then applied random effect meta-analyses to obtain pooled prevalence estimates for all studies and subgroups. Sources of heterogeneity were investigated by moderator analysis, and time trends were assessed through random effect meta-regression. RESULTS Of the 2121 studies identified, 98 were eligible for inclusion. The pooled estimate of 670 572 participants from 26 provinces during 1983-2018 was 49.6% (95% CI: 46.9%, 52.4%). H pylori prevalence varied considerably, ranging from 20.6% to 81.8%. Periods, urban/rural status, detection method, and study design explained 18.8%, 24.0%, 17.8%, and 30.4% of the heterogeneity, respectively. Overall, H pylori prevalence declined by -0.9% (95% CI: -1.1%, -0.6%) annually. Consistent declines in prevalence were observed by sex, age, and study characteristics. CONCLUSIONS Helicobacter pylori prevalence is slowly decreasing over time in mainland China, but the low declining speed is not enough to have a major impact on gastric cancer incidence for many years. The time trends and the large heterogeneity should be taken into account when conducting regional comparisons, disease burden estimations, and customized strategy making.
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Soto AM, Sonnenschein C. Information, programme, signal: dead metaphors that negate the agency of organisms. INTERDISCIPLINARY SCIENCE REVIEWS : ISR 2020; 45:331-343. [PMID: 33100483 PMCID: PMC7577589 DOI: 10.1080/03080188.2020.1794389] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The metaphorical adoption of the concepts of information, program and signal introduced into biology the logic and implicit causal structure of the mathematical theories of information; this is inimical to biology. In turn, those metaphors have hindered the development of a theory of organisms by transferring the agency of organisms to natural selection and to DNA. Moreover, those metaphors introduced into biology the dualism software-hardware and a Laplacian causal structure. Instead, we propose to uphold the agency of the living by adopting three foundational principles for a theory of organisms: namely, 1) the principle of biological inertia (i.e., the default state of cells is proliferation and motility), 2) the principle of variation, and 3) the principle of organization.
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Tague RG. Rudimentary, "functionless" first metapodials of Canis latrans: Variation and association in length with longer, functional metapodials. Evolution 2020; 74:2465-2482. [PMID: 32969028 DOI: 10.1111/evo.14100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 08/20/2020] [Accepted: 09/13/2020] [Indexed: 11/30/2022]
Abstract
A tenet of evolutionary theory is that phenotypic variation of a trait is inversely related to the intensity of stabilizing selection pressure. Among homologous bones, such as metapodials, a rudimentary, "nonfunctional" bone is expected to be more variable in length than nonrudimentary bones. This study compares variation and association in length among metapodials using 277 adult skeletons of Canis latrans. Canis latrans has a short, "functionless" first metacarpal (mc1) and "rudimentary, vestigial" first metatarsal (mt1). Results show that among the 10 metapodials, mt1 has the highest variation in length; other metapodials do not differ significantly from one another in their variation. Correlation coefficients for length of mc1 and mt1 with their ipsilateral metapodials 2-5 are significantly lower than coefficients for all other ipsilateral pairs. The correlation coefficient between left and right mt1 is significantly the lowest among all bilateral pairs of metapodials. Results are interpreted as follows. Mt1's high variation and low association in length are the outcome of less intense stabilizing selection pressure compared with other metapodials. The nonsignificant difference for variation in length between mc1 and metapodials 2-5 may be that mc1 is functional for development of a pollical dewclaw that helps restrain small prey.
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Gould FDH, Lammers AR, Mayerl C, Ohlemacher J, German RZ. Muscle activity and kinematics show different responses to recurrent laryngeal nerve lesion in mammal swallowing. J Neurophysiol 2020; 124:1743-1753. [PMID: 32966748 DOI: 10.1152/jn.00409.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Understanding the interactions between neural and musculoskeletal systems is key to identifying mechanisms of functional failure. Mammalian swallowing is a complex, poorly understood motor process. Lesion of the recurrent laryngeal nerve, a sensory and motor nerve of the upper airway, results in airway protection failure (liquid entry into the airway) during swallowing through an unknown mechanism. We examined how muscle and kinematic changes after recurrent laryngeal nerve lesion relate to airway protection in eight infant pigs. We tested two hypotheses: 1) kinematics and muscle function will both change in response to lesion in swallows with and without airway protection failure, and 2) differences in both kinematics and muscle function will predict whether airway protection failure occurs in lesion and intact pigs. We recorded swallowing with high-speed videofluoroscopy and simultaneous electromyography of oropharyngeal muscles pre- and postrecurrent laryngeal nerve lesion. Lesion changed the relationship between airway protection and timing of tongue and hyoid movements. Changes in onset and duration of hyolaryngeal muscles postlesion were less associated with airway protection outcomes. The tongue and hyoid kinematics all predicted airway protection outcomes differently pre- and postlesion. Onset and duration of activity in only one infrahyoid and one suprahyoid muscle showed a change in predictive relationship pre- and postlesion. Kinematics of the tongue and hyoid more directly reflect changes in airway protections pre- and postlesion than muscle activation patterns. Identifying mechanisms of airway protection failure requires specific functional hypotheses that link neural motor outputs to muscle activation to specific movements.NEW & NOTEWORTHY Kinematic and muscle activity patterns of oropharyngeal structures used in swallowing show different patterns of response to lesion of the recurrent laryngeal nerve. Understanding how muscles act on structures to produce behavior is necessary to understand neural control.
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Natsis K, Antonopoulos I, Politis C, Nikolopoulou E, Lazaridis N, Skandalakis GP, Chytas D, Piagkou M. Pterional variable topography and morphology. An anatomical study and its clinical significance. Folia Morphol (Warsz) 2020; 80:994-1004. [PMID: 32896866 DOI: 10.5603/fm.a2020.0113] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 07/26/2020] [Accepted: 07/27/2020] [Indexed: 11/25/2022]
Abstract
BACKGROUND Pterion is the junction of the frontal, parietal, greater wing of the sphenoid and the squamous part of the temporal bone. The sphenoparietal, frontotemporal, stellate and epipteric pteria were described. The current study determines pterion topography, morphology (variant types' frequency) and morphometry, as well as epipteric bones presence in dried skulls. Gender impact is underlined as well. MATERIALS AND METHODS Ninety Greek adult dried skulls were observed. The distances in between pterion and the zygomatic arch midpoint and in between pterion and the frontozygomatic suture were measured. RESULTS The sphenoparietal pterion was the commonest (58.3%), following by the stellate (25%), epipteric (15.5%) and by the frontotemporal pterion (1.1%). Twenty-eight (15.5%) skulls had epipteric bones, further categorised as quadrisutural (35.7%), trisutural (57.1%), bisutural and multiple (3.57%). The mean distances between pterion and the midpoint of zygomatic arch were 4.13 ± 0.45 cm on the right and 4.09 ± 0.47 cm on the left side and between pterion and the frontozygomatic suture were 3.47 ± 0.61 cm on the right and 3.52 ± 0.65 cm on the left side. Both distances were symmetrical. Male skulls showed slightly higher values on the left side for the distance (pterion-midpoint of zygomatic arch). CONCLUSIONS Pterion is a commonly used neurosurgical landmark and thus in depth knowledge of the pteric area and its variants could be valuable. Recognition of the possible variability in pterion location, morphology and morphometry, as well as possible occurrence of epipteric bones may render pterional craniotomy safer among different population groups.
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Kwak SC, Won HS, Kim YD, Kim WK, Nam YS. Morphologic and morphometric characteristics of the adductor minimus in Korean: its topographic relationship with respect to neighboring anatomical structure and clinical significance. Folia Morphol (Warsz) 2020; 80:963-971. [PMID: 32896868 DOI: 10.5603/fm.a2020.0111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 08/27/2020] [Accepted: 08/27/2020] [Indexed: 11/25/2022]
Abstract
BACKGROUND The aim of this study was to clarify the morphologic and morphometric characteristics of the adductor minimus (AMi) and to observe its topographic relationships relative to the adjacent anatomical structures. MATERIALS AND METHODS This study investigated 54 thighs of 27 Korean cadavers. RESULTS The AMi was a small and flat muscle observed in 94.4% of the specimens. It originated from the inferior ramus of the pubis as the upper part of the adductor magnus (AMa), and inserted from the lesser trochanter to the upper part of the linea aspera. The AMi was completely separate from the AMa in 63.0% of the specimens. The medial circumflex femoral artery was always found at the superior border of the AMi, while the first and second perforating arteries were found inferior to the muscle in 55.6% and 37.0% of specimens, respectively. A supernumerary muscle (SM) was found with the AMi in 42.6% of the specimens, and it originated from the inferior ramus of the pubis and inserted into the posterior side of the lesser trochanter. The obturator externus and AMi were found superoposterior and inferior to the SM, respectively, while the posterior branch of the obturator nerve passed underneath it. CONCLUSIONS The results of this study may provide physicians with the accurate anatomical knowledge that they require for managing groin pain and applying a regional nerve block with ultrasound guidance in this adductor region.
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Xu W, Wang M, Yu D, Zhang X. Variations in SARS-CoV-2 Spike Protein Cell Epitopes and Glycosylation Profiles During Global Transmission Course of COVID-19. Front Immunol 2020; 11:565278. [PMID: 33013929 PMCID: PMC7509417 DOI: 10.3389/fimmu.2020.565278] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Accepted: 08/14/2020] [Indexed: 01/10/2023] Open
Abstract
Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has led to an outbreak of a pandemic worldwide. For better understanding the viral spike (S) protein variations and its potential effects on the interaction with the host immune system and also in vaccine development, the cell epitopes, glycosylation profile and their changes during the global transmission course were characterized and compared with SARS-CoV for their glycosylation profile. We analyzed totally 7,813 sequences screened from 8,897 whole genome sequences on GISAID database up to April 26, and 18 S protein amino acid variations with relatively high frequency (≥10-3) were identified. A total of 228 sequences of variants had multiple variations, of note, most of them harboring the D614G mutation. Among the predicted 69 linear B cell epitopes, 175 discontinuous B cell epitopes and 41 cytotoxic T lymphocyte epitopes in the viral S protein, we found that the protein structure and its potential function of some sites changed, such as the linear epitope length shortened and discontinuous epitope disappeared of G476S. In addition, we detected 9 predicted N-glycosylation sites and 3 O-glycosylation sites unique to SARS-CoV-2, but no evidently observed variation of the glycan sites so far. Our findings provided an important snapshot of temporal and geographical distributions on SARS-CoV-2 S protein cell epitopes and glycosylation sites, which would be an essential basis for the selection of vaccine candidates.
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309
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Guinguina A, Yan T, Lund P, Bayat AR, Hellwing ALF, Huhtanen P. Between-cow variation in the components of feed efficiency. J Dairy Sci 2020; 103:7968-7982. [PMID: 32684452 DOI: 10.3168/jds.2020-18257] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Accepted: 05/01/2020] [Indexed: 11/19/2022]
Abstract
A meta-analysis based on an individual-cow data set was conducted to investigate between-cow variations in the components and measurements of feed efficiency (FE) and to explore the associations among these components. Data were taken from 31 chamber studies, consisting of a total of 841 cow/period observations. The experimental diets were based on grass or corn silages, fresh grass, or a mixture of fresh grass and straw, with cereal grains or by-products as energy supplements, and soybean or canola meal as protein supplements. The average forage-to-concentrate ratio across all diets on a dry matter basis was 56:44. Variance component and repeatability estimates of FE measurements and components were determined using diet, period, and cow within experiment as random effects in mixed procedures of SAS (SAS Institute Inc., Cary, NC). The between-cow coefficient of variation (CV) in gross energy intake (GE; CV = 0.10) and milk energy (El) output as a proportion of GE (El/GE; CV = 0.084) were the largest among all component traits. Similarly, the highest repeatability estimates (≥0.50) were observed for these 2 components. However, the between-cow CV in digestibility (DE/GE), metabolizability [metabolizable energy (ME)/GE], methane yield (CH4E/GE), proportional urinary energy output (UE/GE), and heat production (HP/GE), as well as the efficiency of ME use for lactation (kl), were rather small. The least repeatable component of FE was UE/GE. For FE measurements, the between-cow CV in residual energy-corrected milk (RECM) was larger than for residual feed intake (RFI), suggesting a greater possibility for genetic gain in RECM than in RFI. A high DE/GE was associated with increased CH4E/GE (r = 0.24), HP/GE (r = 0.12), ME/GE (r = 0. 91), energy balance as a proportion of GE (EB/GE; r = 0.35), and kl (r = 0.10). However, no correlation between DE/GE and GE intake or UE/GE was observed. Increased proportional milk energy adjusted to zero energy balance (El(0)/GE) was associated with increases in DE/GE, ME/GE, EB/GE, and kl but decreases in UE/GE, CH4E/GE, and HP/GE, with no effect on GE intake. In conclusion, several mechanisms are involved in the observed differences in FE among dairy cows, and reducing CH4E yield (CH4E/GE) may inadvertently result in reduced GE digestibility. However, the selection of dairy cows with improved energy utilization efficiencies offers an effective approach to lower enteric CH4 emissions.
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310
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La Cava W, Moore JH. Learning feature spaces for regression with genetic programming. GENETIC PROGRAMMING AND EVOLVABLE MACHINES 2020; 21:433-467. [PMID: 33343224 PMCID: PMC7748157 DOI: 10.1007/s10710-020-09383-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 01/17/2020] [Indexed: 06/07/2023]
Abstract
Genetic programming has found recent success as a tool for learning sets of features for regression and classification. Multidimensional genetic programming is a useful variant of genetic programming for this task because it represents candidate solutions as sets of programs. These sets of programs expose additional information that can be exploited for building block identification. In this work, we discuss this architecture and others in terms of their propensity for allowing heuristic search to utilize information during the evolutionary process. We investigate methods for biasing the components of programs that are promoted in order to guide search towards useful and complementary feature spaces. We study two main approaches: 1) the introduction of new objectives and 2) the use of specialized semantic variation operators. We find that a semantic crossover operator based on stagewise regression leads to significant improvements on a set of regression problems. The inclusion of semantic crossover produces state-of-the-art results in a large benchmark study of open-source regression problems in comparison to several state-of-the-art machine learning approaches and other genetic programming frameworks. Finally, we look at the collinearity and complexity of the data representations produced by different methods, in order to assess whether relevant, concise, and independent factors of variation can be produced in application.
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311
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Liu Q, Fu X. The genetic variations in the mitochondrial genomes of three Luciolinae fireflies. Mitochondrial DNA B Resour 2020; 5:3210-3214. [PMID: 33458115 PMCID: PMC7783030 DOI: 10.1080/23802359.2020.1806126] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 08/01/2020] [Indexed: 10/29/2022] Open
Abstract
This paper studied the complete mitochondrial genomes of three fireflies, Pygoluciola qingyu, Emeia pseudosauteri and Abscondita terminalis. We discussed the variations in the mitochondrial genomes of samples of each firefly from different populations. The mitochondrial genomes of Abs. terminalis and P. qingyu are very stable among their different populations. The mitochondrial genome of E. pseudosauteri shows some variations among the different populations, especially in the COI sequence.
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Ma M, Sang H, Ye Y, Zhuang H, Zhuang Z, Qiu Y, Li X, Xu D, Jiang MH. An analysis of the variations and clinical applications of the lateral circumflex femoral artery. Folia Morphol (Warsz) 2020; 80:557-566. [PMID: 32827310 DOI: 10.5603/fm.a2020.0094] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 07/08/2020] [Accepted: 07/08/2020] [Indexed: 11/25/2022]
Abstract
BACKGROUND Identifying the arterial variation of the lateral circumflex femoral artery (LCFA) is a vital step in planning surgical and radiological approach. The aim of the study was to evaluate the variations and discuss the clinical correlates of the LCFA. MATERIALS AND METHODS Fifty eight adult cadavers (male 45, female 13) with 115 usable sides were used to assess and classify the origin and branches of the LCFA. Also its external diameter, distance from mid-inguinal ligament to sites of origin from the profunda femoris artery or femoral arteries. RESULTS There were seven types of LCFA variations in this sample. We classified them as types A to G, of which type A was normal, that is, the one showing a single LCFA arising from the profunda femoris artery. Nearly 50.43% of the sample had type B-G variations, each having 13, 10, 23, 4, 4, and 3 cases, accounting for 11.30%, 8.70%, 20.00%, 3.48%, 3.48%, and 2.61%, respectively. CONCLUSIONS There are many variant types in the LCFA. To avoid iatrogenic injuries, clinicians must have a sound understanding of the variation types of this important blood vessel.
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Associations between the Bovine Myostatin Gene and Milk Fatty Acid Composition in New Zealand Holstein-Friesian × Jersey-Cross Cows. Animals (Basel) 2020; 10:ani10091447. [PMID: 32824948 PMCID: PMC7552700 DOI: 10.3390/ani10091447] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 08/11/2020] [Accepted: 08/15/2020] [Indexed: 11/29/2022] Open
Abstract
Simple Summary The gene that encodes myostatin influences more than one trait, and its expression has been observed in skeletal muscle, as well as the mammary gland. In this study, association analysis revealed that variation in the bovine myostatin gene affects milk fatty acid composition, raising the possibility that this genetic variation may be utilized to increase the amount of unsaturated fatty acid and decrease the amount of saturated fatty acid in milk. Abstract The myostatin gene (MSTN), which encodes the protein myostatin, is pleiotropic, and its expression has been associated with both increased and decreased adipogenesis and increased skeletal muscle mass in animals. In this study, the polymerase chain reaction, coupled with single strand conformation polymorphism analysis, was utilized to reveal nucleotide sequence variation in bovine MSTN in 410 New Zealand (NZ) Holstein-Friesian × Jersey (HF × J)-cross cows. These cows ranged from 3 to 9 years of age and over the time studied, produced an average 22.53 ± 2.18 L of milk per day, with an average milk fat content of 4.94 ± 0.17% and average milk protein content of 4.03 ± 0.10%. Analysis of a 406-bp amplicon from the intron 1 region, revealed five nucleotide sequence variants (A–E) that contained seven nucleotide substitutions. Using general linear mixed-effect model analyses the AD genotype was associated with reduced C10:0, C12:0, and C12:1 levels when compared to levels in cows with the AA genotype. These associations in NZ HF × J cross cows are novel, and they suggest that this variation in bovine MSTN could be explored for increasing the amount of milk unsaturated fatty acid and decreasing the amount of saturated fatty acid.
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van Schaik JE, Slim T, Franse RK, Raijmakers MEJ. Hands-On Exploration of Cubes' Floating and Sinking Benefits Children's Subsequent Buoyancy Predictions. Front Psychol 2020; 11:1665. [PMID: 32793051 PMCID: PMC7385235 DOI: 10.3389/fpsyg.2020.01665] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 06/18/2020] [Indexed: 11/13/2022] Open
Abstract
Children accrue experiences with buoyancy on a daily basis, yet research paints a mixed picture of children's buoyancy knowledge. Whereas children's predictions and explanations of the floating and the sinking of common objects are often based on a single feature (e.g., mass or facts), children's predictions of novel cubes reveal solution strategies based on mass and volume integrations. Correspondingly, category learning theory suggests that categories (e.g., floaters vs. sinkers) are easier to identify when items mainly vary from one another in the relevant defining features. For example, a set of cubes only varies in mass and volume and hence density, thereby being able to highlight the deterministic role of density when placed in water. Here we asked how item variation during hands-on exploration affects children's subsequent predictions and explanations of buoyancy. Kindergarteners and first-, second-, and third-grade children individually explored either a set of 10 systematically varied cubes (i.e., systematic condition; n = 95) or a set of 10 common objects (i.e., non-systematic condition; n = 96) in a water basin. Next, the children predicted the buoyancy of five new cubes and five new common objects one at a time. Subsequently, the children explained their predictions one subset at a time. The children in the systematic condition were more accurate in their predictions of the test cubes than the children in the non-systematic condition. Latent class regression analyses identified three cube prediction solution strategies. The children in the systematic condition were more likely to use a strategy in which buoyancy decisions were made based on an accurate integration of mass and volume, while the children in the non-systematic condition were more likely to use a strategy in which mass was given more predictive load than volume. A third strategy was characterized by guessing. Latent class analyses of the children's explanations revealed different explanation strategies, each appealing to several features, but as hypothesized, no clear condition differences were found. The findings indicate that even 5 min of exploration with systematically varied cubes can already help children use an advanced buoyancy prediction strategy. This provides evidence in favor of using category learning theory to inform early science education design.
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Çavdar S, Solmaz B, Taniş Ö, Guler OU, Dalçık H, Aydoğmuş E, Altunkaya L, Kara E, Aslıyüksek H. Anatomic variations of the human falx cerebelli and its association with occipital venous sinuses. Br J Neurosurg 2020; 35:306-312. [PMID: 32781846 DOI: 10.1080/02688697.2020.1793907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
PURPOSE Human falx cerebelli is an important anatomical structure in regard to its relations with venous structures during infratentorial approach to reach cerebellar tumors, vascular malformations, traumatic hemorrhage and Chiari malformations. The present study aim to describe the different types of variations of the falx cerebelli, its morphological features and its association with occipital venous sinuses. METHOD In this study 49 dura mater was obtained from the Institution of Forensic Medicine. The length, width and the depth of the falx cerebelli were measured using a digital compass. The data obtained were statistically analyzed in relation to age and gender. The relations of the falx cerebelli with the occipital sinus was documented. Histological sections from the falx cerebelli were stained with Hematoxylin Eosin to evaluate the fine structure. RESULTS Among the 49 falx cerebelli examined 36 (73.5%) were classified as normal. The average length, width and depth of the normal falx cerebelli was 3.7, 1.0 and 0.4 cm respectively. Of the 49 falx cerebelli in 1 (2%) case it was absent, in 5 cases (10.2%) duplicate, in 5 cases (10.2%) triplicate, in 1 (2%) case quadruplets and in 1 case (2%) it was five-folded. The proximal and the distal attachments of the falx cerebelli showed 3 types of variations; both attachments triangular, the proximal attachments triangular and the distal ramified and distal attachments triangular and the proximal attachments ramified. The drainage of the occipital sinus of falx cerebelli with variations were evaluated. The increased number of falx cerebelli highly corresponded with the increased number of occipital sinus. CONCLUSIONS The dural-venous variation in the posterior cranial fossa can be problematic in various diagnostic and operative procedures of this region. Neurosurgeons should be aware of such variations, as these could be potential sources of haemorrhage during the midline suboccipital and infratentorial approaches.
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Estimation of between-Cow Variability in Nutrient Digestion of Lactating Dairy Cows Fed Corn-Based Diets. Animals (Basel) 2020; 10:ani10081363. [PMID: 32781738 PMCID: PMC7460325 DOI: 10.3390/ani10081363] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/01/2020] [Accepted: 08/04/2020] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Cow variability present in nutrient digestibility studies differs for different diets and nutrients. It is a major factor determining adequate sample size so that studies are not under-powered or over-powered. The objective of the current study was to develop cow variability estimates that can be used to determine the optimal sample size for digestibility trials having randomized block designs using mid-lactation dairy cows when fed corn-based diets having different neutral detergent fiber:starch ratio (0.7, 1.0, and 1.3). Cow variability is greater for digestibility of fiber and dry matter and less for starch. Estimated cow variability as standard deviations for digestibility of dry matter, neutral detergent fiber and starch were 3.8 g/kg, 5.1 g/kg and 3.3 g/kg, respectively. A major implication of this study is that cow variability is greatest for fiber digestibility and the use of a minimum of 12 cows per dietary treatment is adequate to reliably detect treatment effects on the digestibility of fiber, starch and dry matter using lactating dairy cows fed in groups with randomized block design under current experimental conditions. Abstract The objective of this study was to estimate cow variability that can be used to determine the optimal sample size for digestibility trials using lactating dairy cows. Experimental design was randomized complete block design having three blocks and three dietary treatments. Three similarly managed nearby intensive farms were considered as blocks, and three diets were formulated to have 0.7, 1.0, and 1.3 neutral detergent fiber (NDF): starch ratio. In each farm, 18 cows were assigned for each dietary treatment and five sample sizes per each treatment group were simulated by simple random sampling of data from 18, 15, 12, 9 and 6 cows respectively. Intake was not affected by diet or sample size (p > 0.05). Estimated cow variability (as standard deviation) for digestibility of dry matter, NDF and starch were 3.8 g/kg, 5.1 g/kg and 3.3 g/kg, respectively. A major implication of this study is that cow variability is greatest for NDF digestibility and the use of a minimum of 12 cows per dietary treatment is adequate to reliably detect treatment effects on the digestibility of NDF, starch and dry matter using cows fed in groups with randomized block design under these experimental conditions.
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Jones JD, Castanho P, Bazira P, Sanders K. Anatomical variations of the circle of Willis and their prevalence, with a focus on the posterior communicating artery: A literature review and meta-analysis. Clin Anat 2020; 34:978-990. [PMID: 32713011 DOI: 10.1002/ca.23662] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 04/25/2020] [Accepted: 07/20/2020] [Indexed: 11/11/2022]
Abstract
The circle of Willis is an anastomotic network of arteries surrounding the base of the brain, providing collateral circulation to prevent ischemia. It has, however, long been established that it exhibits considerable anatomical variation when compared to Thomas Willis' originally described circle. This study aimed primarily to determine an accurate prevalence of the variation of the circle of Willis in the general population and the prevalence of common posterior communicating artery variations. Additional aims were to explain why such a wide range of reported variations exist, and whether different types of studies report significantly different prevalence of variation. A comprehensive literature search identified 764 papers. A three-phase screening process was undertaken, involving a critical analysis of papers, and a total of 33 papers were selected for analysis and literature review. A descriptive statistics test with bootstrap was performed to estimate the average prevalence of variations. The estimated prevalence of general variation, unilateral, and bilateral posterior communicating artery hypoplasia or aplasia was 68.22 ± 14.32%, 19.45 ± 8.63%, and 22.83 ± 14.58%, respectively. Over half of the population exhibit a circle of Willis with some form of variation. To provide a more accurate estimation for the prevalence of variations, a universal classification system needs to be established, collating all the work from high-quality studies, to provide a comprehensive database of the circle's variations. Knowing the prevalence of variations and how they can impact neurosurgical approaches or patterns of ischemic pathology can be crucial in providing effective patient care.
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Piagkou M, Kapetanakis S, Tsakotos G, Samolis A, Anastasopoulos N, Natsis K. A Rare Case of Posterior Tibial Artery Hypoplasia and Fibular Artery Enlargement and their Impact on the Arterial Supply of Posterior Crural Region. Folia Med (Plovdiv) 2020; 61:467-471. [PMID: 32337936 DOI: 10.3897/folmed.61.e39414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Accepted: 03/28/2019] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Detailed knowledge of the popliteal artery division and possible anatomical variants is of paramount importance for vascular surgery. AIM The aim of the current study was to highlight a rare unilateral case of posterior tibial artery hypoplasia. MATERIALS AND METHODS A dissection was performed at the posterior surface of the tibia in a 78-year-old Caucasian male cadaver of Greek origin. RESULTS The findings were consistent with unilateral posterior tibial artery hypoplasia and fibular artery enlargement. The variant fibular artery supplied the posterior surface of the distal leg and foot. Clinical implications of the fibular artery dominance are discussed. CONCLUSIONS Rare anatomical variants of the tibial artery are of clinical significance to maximize safety and minimize intraoperative complications.
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Ben Abdelaziz R, Tangour N, Ben Chehida A, Haj Taieb S, Feki M, Azzouz H, Tebib N. Morning specimen is not representative of metabolic control in Tunisian children with phenylketonuria: a repeated cross-sectional study. J Pediatr Endocrinol Metab 2020; 33:/j/jpem.ahead-of-print/jpem-2020-0025/jpem-2020-0025.xml. [PMID: 32653876 DOI: 10.1515/jpem-2020-0025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 05/04/2020] [Indexed: 11/15/2022]
Abstract
Objective and methods To evaluate variation of capillary phenylalanine concentrations over the day in patients treated for phenylketonuria and the reliability of the morning sample to assess metabolic control, we conducted a repeated cross-sectional study in 25 Tunisian patients on phenylalanine-low diet. For each patient, we collected nine capillary samples over the day. Phenylalanine was dosed by fluorimetry. Results There was a wide variability of phenylalanine concentrations over the day (p<0.001). Compared to morning sample, phenylalanine concentration was significantly lower before lunch (p=0.038), after lunch (p=0.025), before dinner (p<0.001), after dinner (p=0.035) and at 4:00 a.m. (p=0.011). Compared to the 24 h sampling, the morning sample had a 68% to identify unbalanced patients. 60% of patients, had peak phenylalanine concentration after the morning. Half of the patients with normal morning phenylalanine concentration had low phenylalanine values over 8-20 h. Percentages of high phenylalanine concentrations over the last semester were higher in patients with poor metabolic control over the 24 h (21% ± 43 vs. 0% ± 9%); p=0.043. Conclusion A single morning sample gives an incomplete information on metabolic control in phenylketonuric patients. Using four pre-prandial samples on the day should be considered as alternative in patients with good metabolic control.
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Mansour Y, Kulesza R. A tale of two arteries: dual posterior cerebral arteries with vascular bridges. A possible protective pattern? Folia Morphol (Warsz) 2020; 80:455-459. [PMID: 32644187 DOI: 10.5603/fm.a2020.0070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 07/01/2020] [Accepted: 07/01/2020] [Indexed: 11/25/2022]
Abstract
Stroke is a common morbidity and a frequent cause of disability and even death. The impact of cerebrovascular events is dictated by the brain region involved and can be complicated by anatomical variations. One of the most common variations impacting the cerebral vasculature is the presence of a foetal posterior cerebral artery. This vessel arises from the internal carotid artery instead of the basilar artery and is often associated with more extensive injury in cerebrovascular events. Herein, we report the case of a 60-year-old male who had numerous arterial abnormalities, including a kink and a coil of the left internal carotid, two posterior communicating arteries on the right and two posterior cerebral arteries (PCA) on the left, one arising from the internal carotid (foetal PCA) and one from the basilar. The foetal PCA supplied the thalamus, splenium of the corpus callosum and primary visual cortex. The basilar PCA supplied the midbrain and parts of the occipital lobe. These PCA were connected to each other by a vascular bridge and the foetal PCA was connected to the middle cerebral artery by an additional vascular bridge. This vascular pattern would appear to provide collateral support around blockages in the internal carotid and main stem middle and PCA.
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Sponholtz TR, van den Heuvel ER, Xanthakis V, Vasan RS. Association of Variability in Body Mass Index and Metabolic Health With Cardiometabolic Disease Risk. J Am Heart Assoc 2020; 8:e010793. [PMID: 31025893 PMCID: PMC6509716 DOI: 10.1161/jaha.118.010793] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Background Metabolic syndrome is associated with high risk of cardiovascular disease, although risk may differ according to the specific conditions present and variability in those conditions. Methods and Results We defined obesity (body mass index [BMI] ≥30 kg/m2) and metabolic health (<2 nonobesity National Cholesterol Education Program Adult Treatment Panel III conditions) among 3632 Framingham Heart Study offspring cohort participants (mean age, 50.8 years; 53.8% women) who were followed up from 1987 to 2014. We defined participants whose variance independent of the mean for a metabolic syndrome-associated measure was in the top quintile as being "variable" for that measure. Variable metabolic health was defined as ≥2 variable nonobesity metabolic syndrome components. We investigated the interaction between obesity and metabolic health in their associations with cardiometabolic disease and cardiovascular disease using Cox proportional hazards regression. In addition, we estimated the associations of BMI variability and variable metabolic health with study outcomes within categories of obesity and metabolic health status, respectively. We observed 567 incident obesity (41 439 person-years), 771 incident metabolically unhealthy state (25 765 person-years), 272 incident diabetes mellitus (56 233 person-years), 503 incident hypertension (12 957 person-years), 589 cardiovascular disease (60 300 person-years), and 195 chronic kidney disease (47 370 person-years) events on follow-up. Obesity and being metabolically unhealthy were independently and positively associated with all outcomes. BMI variability, compared with stable BMI, was associated with 163%, 67%, 58%, and 74% higher risks of having obesity, becoming metabolically unhealthy, having diabetes mellitus, and having hypertension, respectively, among nonobese participants. Variable metabolic health, compared with stable metabolic health, was associated with a 28% higher risk of cardiovascular disease, among metabolically healthy participants. Conclusions We did not observe evidence for a positive interaction between obesity and metabolic health status with regard to study outcomes. BMI and metabolic health variability are associated with adverse health outcomes.
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Eng OS, Blakely AM, Lafaro KJ, Fournier KF, Fackche NT, Johnston FM, Dineen S, Powers B, Hendrix R, Lambert LA, Ronnekleiv-Kelly S, Walle KV, Grotz TE, Leiting JL, Patel SH, Dhar VK, Baumgartner JM, Lowy AM, Clarke CN, Mogal H, Zaidi MY, Staley CA, Kimbrough C, Cloyd JM, Lee B, Raoof M. Institutional variation in recovery after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy: An opportunity for enhanced recovery pathways. J Surg Oncol 2020; 122:980-985. [PMID: 32627199 DOI: 10.1002/jso.26099] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 06/23/2020] [Indexed: 12/20/2022]
Abstract
BACKGROUND Variations in care have been demonstrated both within and among institutions in many clinical settings. By standardizing perioperative practices, Enhanced Recovery After Surgery (ERAS) pathways reduce variation in perioperative care. We sought to characterize the variation in cytoreductive surgery (CRS)/heated intraperitoneal chemotherapy (HIPEC) perioperative practices among experienced US medical centers. METHODS Data from the US HIPEC Collaborative represents a retrospective multi-institutional cohort study of CRS and CRS/HIPEC procedures performed from 12 major academic institutions. Patient characteristics and perioperative practices were reported and compared. Institutional variation was analyzed using hierarchical mixed-effects linear (continuous outcomes) or logistic (binary outcomes) regression models. RESULTS A total of 2372 operations were included. CRS/HIPEC was performed most commonly for appendiceal histologies (64.2%). The rate of complications (overall 56.3%, range: 31.8-70.9) and readmissions (overall 20.6%, range: 8.9-33.3) varied by institution (P < .001). Institution-level variation in perioperative practice patterns existed among measured ERAS pathway process/outcomes (P < .001). The percentages of variation with each process/outcome measure attributable solely to institutional practices ranged from 0.6% to 66.6%. CONCLUSIONS Significant variation exists in the perioperative care of patients undergoing CRS/HIPEC at major US academic institutions. These findings provide a strong rationale for the investigation of best practices in CRS/HIPEC patients.
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Lewin AC, Liu CC, Camacho-Luna P, Alling C, Carter RT. Inter-user and intra-user variation of two tonometers in horses. Equine Vet J 2020; 52:572-576. [PMID: 31721273 DOI: 10.1111/evj.13208] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 09/02/2019] [Accepted: 10/31/2019] [Indexed: 12/22/2022]
Abstract
BACKGROUND It is currently unknown which of the two devices most commonly used in equine ophthalmology for intraocular pressure (IOP) estimation demonstrates the lowest inter-user and intra-user variation. OBJECTIVES To assess the inter-user and intra-user variation of two tonometers in sedated and unsedated horses. STUDY DESIGN Randomised masked cross-over trial. METHODS Four examiners used the rebound (ICare® TonoVet) and applanation (TonoPen® ) tonometers to measure the intraocular pressure (IOP) in triplicate in 10 normal horses before and after sedation with xylazine. For inter-user variation, coefficient of variation (CV) values were calculated from the mean of each examiner for each condition combination. For intra-user variation, CV values were calculated from the individual measurements of each examiner for each condition combination. CV values were also assessed in relation to other variables using ANOVA. RESULTS The rebound tonometer was found to have lower inter-user (15.4% vs 21.7%, P = .01) and intra-user (9.1% vs 16.1%, P < .0001) variation in unsedated horses and lower intra-user (8.4% vs 14.7%, P < .0001) variation in sedated horses than the applanation tonometer. Both instruments had similar inter-user variation in sedated horses. For the rebound tonometer, sedation did not affect inter-user or intra-user variation, but for the applanation tonometer inter-user variation was lowest while horses were sedated (16.0% vs 21.7%, P = .03). No other variable assessed was found to have an effect on IOP. MAIN LIMITATIONS No animals with ocular disease were included in this study. CONCLUSIONS The rebound tonometer may be the preferred instrument to minimise intra-user and inter-user variation for IOP measurement in unsedated horses. The rebound tonometer is also likely to be the preferred instrument to minimise intra-user variation in sedated horses. If the applanation tonometer is used to perform IOP measurement in horses, it is recommended that this is performed while horses are sedated to minimise inter-user variation for this instrument.
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Renzulli M, Pagano N, Golfieri R. Pancreas divisum inversus. Clin Anat 2020; 33:646-652. [PMID: 31576611 DOI: 10.1002/ca.23475] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 08/30/2019] [Accepted: 09/14/2019] [Indexed: 12/26/2022]
Abstract
Pancreatic duct variations are usually diagnosed incidentally, in particular when using magnetic resonance cholangiopancreatography (MRCP), the most accurate imaging modality for depicting the pancreatic ductal system. However, the frequency and the embryologic development of pancreatic variants have not been well investigated. The purpose of this prospective study was to investigate the frequency of pancreatic ductal variants, providing potential explanations of their embryologic basis. The pancreatic ductal anatomies of 202 patients with mean ± standard deviation (SD) age of 54 ± 27 years, 56% females, who underwent MRCP for different indications between April 2018 and March 2019, were prospectively collected. Normal pancreatic ductal variants were identified in 196 cases (97%), and variants of pancreas divisum in six cases (3%). In the type C variant of the normal pancreatic anatomy, found in 3% of the cases, the dorsal duct was joined to the ventral duct while the accessory duct did not communicate with the dorsal duct. Unlike the classic type C variant, in our cases, the accessory pancreatic duct (APD) was long (mean ± SD of 58 ± 8.5 mm) and originated in the lower portion of the pancreatic head, caudally to the duct of Wirsung. This was a new subtype of the type C variant or a new variant, which could be called "pancreas divisum inversus"; the APD could be called the isolated duct of Santorini. Reporting this new variant could increase knowledge regarding the pancreatic anatomy in order to avoid misdiagnosis and to help in better understanding pancreatic diseases and their relative treatment. Clin. Anat., 33:646-652, 2020. © 2019 Wiley Periodicals, Inc.
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Jiang D, Lin Z, Liu P, Sur S, Xu C, Hazel K, Pottanat G, Yasar S, Rosenberg P, Albert M, Lu H. Normal variations in brain oxygen extraction fraction are partly attributed to differences in end-tidal CO 2. J Cereb Blood Flow Metab 2020; 40:1492-1500. [PMID: 31382788 PMCID: PMC7308520 DOI: 10.1177/0271678x19867154] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Cerebral oxygen extraction fraction is an important physiological index of the brain's oxygen consumption and supply and has been suggested to be a potential biomarker for a number of diseases such as stroke, Alzheimer's disease, multiple sclerosis, sickle cell disease, and metabolic disorders. However, in order for oxygen extraction fraction to be a sensitive biomarker for personalized disease diagnosis, inter-subject variations in normal subjects must be minimized or accounted for, which will otherwise obscure its interpretation. Therefore, it is essential to investigate the physiological underpinnings of normal differences in oxygen extraction fraction. This work used two studies, one discovery study and one verification study, to examine the extent to which an individual's end-tidal CO2 can explain variations in oxygen extraction fraction. It was found that, across normal subjects, oxygen extraction fraction is inversely correlated with end-tidal CO2. Approximately 50% of the inter-subject variations in oxygen extraction fraction can be attributed to end-tidal CO2 differences. In addition, oxygen extraction fraction was found to be positively associated with age and systolic blood pressure. By accounting for end-tidal CO2, age, and systolic blood pressure of the subjects, normal variations in oxygen extraction fraction can be reduced by 73%, which is expected to substantially enhance the utility of oxygen extraction fraction as a disease biomarker.
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