Large Population Sizes Research Articles

Stochastic parabolic growth promotes coexistence and a relaxed error threshold in RNA-like replicator populations

The RNA world hypothesis proposes that during the early evolution of life, primordial genomes of the first self-propagating evolutionary units existed in the form of RNA-like polymers. Autonomous, non-enzymatic, and sustained replication of such information carriers presents a problem, because product formation and hybridization between template and copy strands reduces replication speed. Kinetics of growth is then parabolic with the benefit of entailing competitive coexistence, thereby maintaining diversity. Here, we test the information-maintaining ability of parabolic growth in stochastic multispecies population models under the constraints of constant total population size and chemostat conditions. We find that large population sizes and small differences in the replication rates favor the stable coexistence of the vast majority of replicator species (‘genes’), while the error threshold problem is alleviated relative to exponential amplification. In addition, sequence properties (GC content) and the strength of resource competition mediated by the rate of resource inflow determine the number of coexisting variants, suggesting that fluctuations in building block availability favored repeated cycles of exploration and exploitation. Stochastic parabolic growth could thus have played a pivotal role in preserving viable sequences generated by random abiotic synthesis and providing diverse genetic raw material to the early evolution of functional ribozymes.

Stochastic parabolic growth promotes coexistence and a relaxed error threshold in RNA-like replicator populations.

The RNA world hypothesis proposes that during the early evolution of life, primordial genomes of the first self-propagating evolutionary units existed in the form of RNA-like polymers. Autonomous, non-enzymatic, and sustained replication of such information carriers presents a problem, because product formation and hybridization between template and copy strands reduces replication speed. Kinetics of growth is then parabolic with the benefit of entailing competitive coexistence, thereby maintaining diversity. Here, we test the information-maintaining ability of parabolic growth in stochastic multispecies population models under the constraints of constant total population size and chemostat conditions. We find that large population sizes and small differences in the replication rates favor the stable coexistence of the vast majority of replicator species ('genes'), while the error threshold problem is alleviated relative to exponential amplification. In addition, sequence properties (GC content) and the strength of resource competition mediated by the rate of resource inflow determine the number of coexisting variants, suggesting that fluctuations in building block availability favored repeated cycles of exploration and exploitation. Stochastic parabolic growth could thus have played a pivotal role in preserving viable sequences generated by random abiotic synthesis and providing diverse genetic raw material to the early evolution of functional ribozymes.

Characterizing Infections in Two Epidemic Waves of SARS-CoV-2 Omicron Variants: A Cohort Study in Guangzhou, China.

After the adjustment of COVID-19 epidemic policy, mainland China experienced two consecutive waves of Omicron variants within a seven-month period. In Guangzhou city, as one of the most populous regions, the viral infection characteristics, molecular epidemiology, and the dynamic of population immunity are still elusive. We launched a prospective cohort study in the Guangdong Provincial CDC from December 2022 to July 2023. Fifty participants who received the same vaccination regimen and had no previous infection were recruited. 90% of individuals were infected with Omicron BA.5* variants within three weeks in the first wave. Thirteen cases (28.26%) experienced infection with XBB.1* variants, occurring from 14 weeks to 21 weeks after the first wave. BA.5* infections exhibited higher viral loads in nasopharyngeal sites compared to oropharyngeal sites. Compared to BA.5* infections, the XBB.1* infections had significantly milder clinical symptoms, lower viral loads, and shorter durations of virus positivity. The infection with the BA.5* variant elicited varying levels of neutralizing antibodies against XBB.1* among different individuals, even with similar levels of BA.5* antibodies. The level of neutralizing antibodies specific to XBB.1* determined the risk of reinfection. The rapid large-scale infections of the Omicron variants have quickly established herd immunity among the population in mainland China. In the future of the COVID-19 epidemic, a lower infection rate but a longer duration can be expected. Given the large population size and ongoing diversified herd immunity, it remains crucial to closely monitor the molecular epidemiology of SARS-CoV-2 for the emergence of new variants of concern in this region. Additionally, the timely evaluation of the immune status across different age groups is essential for informing future vaccination strategies and intervention policies.

The Crespo Scale: Categorising 'Dangerous' Animal Species with Two Quantifiable Factors

Throughout our history, humanity and the kingdom Animalia have been in conflicts with both sides sharing countless casualties as the outcome. Among animals, adult female mosquitoes of the Anopheles genus are infamously labelled the deadliest to humans in terms of the number of deaths they cause each year. In this scientific paper, an analysis is given over what other direct and indirect factors can be considered when classifying a species of animal as 'dangerous'. It discusses and concludes exactly why they make it more of a danger to human health and safety than others. This is done utilising a brand-new, categoric scale — which has been dubbed the "Crespo scale" — created and designed to categorise all animal species from categories 1–5. One posing the least danger and five the most. The categorisation is performed by examining factors relevant to the animals themselves, which include the estimated Population Size (PS) and Mortality Rate (MR). The hypothesis is that species possessing a larger PS and a higher MR will be placed further up on the scale and thus are more likely to be a threat. Ultimately, both PS and MR are quantifiable factors that can be used to measure and categorise a species' level of danger in a less biased and more accurate, consistent way. However, the factor of MR can often be indirectly influenced by human-related factors that apply to the human development of a country and its general populace.

How does technological progress affect provincial financial resilience? Evidence at the provincial level in China

The ever-changing global economy and sudden global public health events have posed challenges to financial resilience worldwide. As its important role in maintaining domestic economic stability, safeguarding national security, and enhancing international status, financial resilience has long been widely studied. However, few studies have empirically explored how technological progress affects financial resilience. Based on data from 30 provinces in China, this study adopts a panel two-way fixed effect model to identify the impact of technological progress on financial resilience and the underlying mechanisms. Results show that technological progress can significantly enhance financial resilience, and this impact is stronger in provinces with large population size, high employment proportion in the tertiary sector, high social consumption capacity, and provinces located in Central China. Further, technological progress have a positive impact on financial resilience through increased asset liquidity and government intervention.

Surveys that prioritize site number over time per site will result in better gastropod status assessments: a case study on the rediscovery of Big Black Rocksnail

Freshwater gastropods are among the most imperiled organisms on Earth. Yet, they are among the most understudied freshwater taxa. Numerous freshwater gastropod species have gone extinct in the last 100 years, but recent rediscoveries indicate that some species were prematurely declared extinct. Such premature extinction declarations remove legal protections, which could facilitate actual extinction. Thus, research and policy recommendations are needed so surveys provide the best information possible for conservation. Here, we examined the case of Lithasia hubrichti, a freshwater gastropod endemic to the Big Black River in Mississippi that was last seen in 1965. In 2022, a freshwater mollusk survey resulted in finding L. hubrichti alive. An additional survey effort in 2023 that prioritized sampling as many sites as possible in a single day clarified the current range of L. hubrichti. Genomic analyses indicated that the species has persisted with a large population size for thousands of years, rather than ever falling below a survey detection limit. When considering the case of L. hubrichti and other recent freshwater gastropod rediscoveries, we conclude that freshwater gastropod surveys should emphasize sampling as many sites as possible under favorable sampling conditions when targeting rare species, rather than expending high sampling effort at a small number of sites or when stream conditions may impact ability to detect target species. We also advocate for policies that encourage partnerships with landowners, which was required to rediscover L. hubrichti.

The community background alters the evolution of thermal performance

Abstract Microbes are key drivers of global biogeochemical cycles, and their functional roles arey dependent on temperature. Large population sizes and rapid turnover rates mean that the predominant response of microbes to environmental warming is likely to be evolutionary, yet our understanding of evolutionary responses to temperature change in microbial systems is rudimentary. Natural microbial communities are diverse assemblages of interacting taxa. However, most studies investigating the evolutionary response of bacteria to temperature change are focused on monocultures. Here, we utilize high-throughput experimental evolution of bacteria in both monoculture and community contexts along a thermal gradient to determine how interspecific interactions influence the thermal adaptation of community members. We found that community-evolved isolates tended toward higher maximum growth rates across the temperature gradient compared to their monoculture-evolved counterparts. We also saw little evidence of systematic evolutionary change in the shapes of bacterial thermal tolerance curves along the thermal gradient. However, the effect of community background and selection temperature on the evolution of thermal tolerance curves was variable and highly taxon-specific,with some taxa exhibiting pronounced changes in thermal tolerance while others were less impacted. We also found that temperature acted as a strong environmental filter, resulting in the local extinction of taxa along the thermal gradient, implying that temperature-driven ecological change was a key factor shaping the community background upon which evolutionary selection can operate. These findings offer novel insight into how community background impacts thermal adaptation.

Adverse Drug Events Observed with the Newly Approved Remimazolam in Comparison to Propofol for General Anesthesia in Patients Undergoing Surgery: A Meta-analysis.

Developments in anesthetic pharmacology have been aiming at minimizing physiological disturbance in addition to maintaining and improving titrateability, recovery profile, and patient experience. Remimazolam, a GABAAlpha receptor agonist, is a new intravenous anesthetic agent which has recently been approved for use. This analysis aimed to systematically compare the adverse drug events reported with the newly approved remimazolam in comparison to propofol for general anesthesia (GA) in patients undergoing surgery. Electronic databases were searched from 15 May to 20 December 2023 for relevant publications which compared the outcomes reported with the newly approved remimazolam versus propofol in patients undergoing surgery. Relevant reported adverse drug events were the endpoints of this study. The statistical analysis was carried out using the latest version of the RevMan software. Data analysis was represented by risk ratio (RR) with 95% confidence intervals (CI). Sixteen studies with a total number of 1897 participants were included in this analysis; 1104 participants received remimazolam and 793 participants received propofol. The risks for hypotension (RR 0.50, 95%CI 0.43-0.58; P = 0.00001), hypoxemia (RR 0.43, 95%CI 0.19-0.99; P = 0.05), bradycardia (RR 0.53, 95%CI 0.36-0.78; P = 0.001), pain at injection site (RR 0.07, 95%CI 0.01-0.56; P = 0.01), and total adverse events (RR 0.33, 95%CI 0.24-0.47; P = 0.00001) were significantly lower with remimazolam. However, no significant differences were observed in terms of postoperative nausea and vomiting (RR 0.98, 95%CI 0.66-1.46; P = 0.93), dizziness (RR 0.42, 95%CI 0.11-1.57; P = 0.20), psychiatric symptoms (RR 1.09, 95%CI 0.45-2.67; P = 0.85), and respiratory depression (RR 0.81, 95%CI 0.24-2.76; P = 0.74). Our current analysis showed that the newly approved remimazolam was apparently associated with significantly fewer adverse drug events in comparison to propofol for GA in patients undergoing surgery. Therefore, this new drug should be further studied and more research with larger population sizes should be carried out to confirm this hypothesis.

Testing hypotheses of invasion pathways of the ladybird Harmonia axyridis into and across South Africa

AbstractHarmonia axyridis is an invasive beetle (Coleoptera: Coccinellidae), native to Asia, that has established on four continents beyond its native range and was first observed in South Africa in 2001. Using microsatellite data and a comprehensive geographic coverage of international (17 locations) and South African (14 locations) beetle samples, we inferred the source of colonists invading South Africa and the beetle’s movement within the country. Genetic structure analyses suggest that this species’ populations in South Africa are derived from admixture between beetles originating from eastern North America (which acted as a bridgehead population) and another population not directly sampled in our study. Genetic admixture prior its invasion into South Africa, along with the possibility of multiple introductions from the bridgehead population, may explain the high genetic diversity estimates for South African H. axyridis (HE = 0.582–0.625) compared to beetles from the native range (HE = 0.440–0.636). Harmonia axyridis appear to be frequently exchanging genetic material across South Africa, with no clear genetic structure between sampled locations. However, evidence of weak isolation-by-distance within South Africa suggests that beetles are dispersing less frequently between locations that are furthest apart. This study supports previous findings on global invasion pathways in this species but provides new insights in the context of the invasion in South Africa. We highlight how mixing of distinct lineages from divergent origins prior to the invasion into South Africa has augmented genetic diversity in the region. The high dispersal rates and large effective population sizes inferred from genetic markers suggest that slowing the spread or reducing population abundances of the species in South Africa will be challenging without an integrated, multi-faceted management approach.

Adaptation to seasonal reproduction and environment-associated factors drive temporal and spatial differentiation in northwest Atlantic herring despite gene flow.

Understanding how marine organisms adapt to local environments is crucial for predicting how populations will respond to global climate change. The genomic basis, environmental factors and evolutionary processes involved in local adaptation are however not well understood. Here we use Atlantic herring, an abundant, migratory and widely distributed marine fish with substantial genomic resources, as a model organism to evaluate local adaptation. We examined genomic variation and its correlation with environmental variables across a broad environmental gradient, for 15 spawning aggregations in Atlantic Canada and the United States. We then compared our results with available genomic data of northeast Atlantic populations. We confirmed that population structure lies in a fraction of the genome including likely adaptive genetic variants of functional importance. We discovered 10 highly differentiated genomic regions distributed across four chromosomes. Nine regions show strong association with seasonal reproduction. One region, corresponding to a known inversion on chromosome 12, underlies a latitudinal pattern discriminating populations north and south of a biogeographic transition zone on the Scotian Shelf. Genome-environment associations indicate that winter seawater temperature best correlates with the latitudinal pattern of this inversion. The variation at two so-called 'islands of divergence' related to seasonal reproduction appear to be private to the northwest Atlantic. Populations in the northwest and northeast Atlantic share variation at four of these divergent regions, simultaneously displaying significant diversity in haplotype composition at another four regions, which includes an undescribed structural variant approximately 7.7 Mb long on chromosome 8. Our results suggest that the timing and geographic location of spawning and early development may be under diverse selective pressures related to allelic fitness across environments. Our study highlights the role of genomic architecture, ancestral haplotypes and selection in maintaining adaptive divergence in species with large population sizes and presumably high gene flow.

Population genomic analyses reveal that salinity and geographic isolation drive diversification in a free-living protist

Protists make up the vast diversity of eukaryotic life and play a critical role in biogeochemical cycling and in food webs. Because of their small size, cryptic life cycles, and large population sizes, our understanding of speciation in these organisms is very limited. We performed population genomic analyses on 153 strains isolated from eight populations of the recently radiated dinoflagellate genus Apocalathium, to explore the drivers and mechanisms of speciation processes. Species of this genus inhabit both freshwater and saline habitats, lakes and seas, and are found in cold temperate environments across the world. RAD sequencing analyses revealed that the populations were overall highly differentiated, but morphological similarity was not congruent with genetic similarity. While geographic isolation was to some extent coupled to genetic distance, this pattern was not consistent. Instead, we found evidence that the environment, specifically salinity, is a major factor in driving ecological speciation in Apocalathium. While saline populations were unique in loci coupled to genes involved in osmoregulation, freshwater populations appear to lack these. Our study highlights that adaptation to freshwater through loss of osmoregulatory genes may be an important speciation mechanism in free-living aquatic protists.

High genetic load without purging in caribou, a diverse species at risk

High intra-specific genetic diversity is associated with adaptive potential, which is key for resilience to global change. However, high variation may also support deleterious alleles through genetic load, thereby increasing the risk of inbreeding depression if population sizes decrease. Purging of deleterious variation has been demonstrated in some threatened species. However, less is known about the costs of declines and inbreeding in species with large population sizes and high genetic diversity even though this encompasses many species globally that are expected to undergo population declines. Caribou is a species of ecological and cultural significance in North America with a wide distribution supporting extensive phenotypic variation but with some populations undergoing significant declines resulting in their at-risk status in Canada. We assessed intra-specific genetic variation, adaptive divergence, inbreeding, and genetic load across populations with different demographic histories using an annotated chromosome-scale reference genome and 66 whole-genome sequences. We found high genetic diversity and nine phylogenomic lineages across the continent with adaptive diversification of genes, but also high genetic load among lineages. We found highly divergent levels of inbreeding across individuals, including the loss of alleles by drift but not increased purging in inbred individuals, which had more homozygous deleterious alleles. We also found comparable frequencies of homozygous deleterious alleles between lineages regardless of nucleotide diversity. Thus, further inbreeding may need to be mitigated through conservation efforts. Our results highlight the "double-edged sword" of genetic diversity that may be representative of other species atrisk affected by anthropogenic activities.

Prevalence of chronic kidney disease in Tunisian diabetics: the TUN-CKDD survey.

In Tunisia, the prevalence of diabetes mellitus increased from 15.5% on 2016 to 23% by 2023. While Chronic Kidney Disease (CKD) stills the most dreaded complications of diabetes, studies on the prevalence of chronic kidney disease non-dialysis diet are scarce. The aim of this study was to assess the prevalence of chronic kidney disease among the Tunisian diabetic population based on investigators' specialty, demographic criteria (gender, age, duration of diabetes and geographic distribution) and diagnosis criteria (albuminuria and/or eGFR). This observational, multicentric, and cross-sectional study enrolled all diabetic subjects from all regions of Tunisia with at least 3 months of follow-up before the inclusion date, from 09 January to 08 February 2023. CKD diagnosis was established based on the KDIGO guidelines. The study was carried out at medical departments and ambulatory clinics of different healthcare providers. Baseline data were collected by investigators using an electronic case report form (eCRF). Continuous variables were described by means, median, standard deviation, and quartiles. Categorical data were tabulated in frequencies and percentages. The overall prevalence of CKD among the 10,145 enrolled patients with diabetes mellitus was 38.7% with a 95%CI [37.8-39.6%]. 50.9% were male, with a mean age of 67.5 (± 11.3) years. The mean diabetes duration was 16.1 years (± 8.9). The highest CKD prevalence was noted among nephrologists (82.2%), while it was similar between the cardiologists and the primary care physicians (30.0%). CKD prevalence was highest among males (43.0% versus 35.1%) and increased proportionally with patients' age and diabetes duration. CKD was more frequent in the Mid-East Area when compared to other regions (49.9% versus 25.3 to 40.1% in other regions). Albuminuria was present within 6.6% of subjects with CKD, and it was found an estimated glomerular filtration rate (eGFR) < 60ml/min/1.73m² within 13.3% of subjects wit h CKD. 18.9% had both criteria. In Tunisia, CKD among diabetics had a prevalence of 38.7%, approaching European prevalence. The prevalence discrepancy worldwide of CKD can be improved with a larger population size and by implementing standardized practices.

The Impact of Low-Carbon City Pilot Policies on Green Innovation Efficiency in Chinese Cities: An Empirical Analysis Based on the Multi-Period PSM-DID Model

On the basis of panel data taken from 226 Chinese cities in the period 2008 to 2019, this paper measures urban green innovation efficiency, with the help of the unexpected production output-stochastic block model (UPO-SBM), and applies the propensity score matching difference-in-differences (PSM-DID) model to analyze the impact of low-carbon city pilot policies (LCPP) on urban green innovation efficiency. This paper also applies a mediation effect model to analyze the mechanism of the LCPP that enhances urban green innovation efficiency, and also attempts to explore the impact of the LCPP on the green innovation efficiency of various types of cities by engaging with multiple dimensions. The results of the study shows that: (1) When all other conditions remain unchanged, the average promotion effect of the implementation of the LCPP on urban green innovation efficiency is 21.77%; (2) at 1% significance level, the mediating effect of financial technology R&amp;D expenditure and environmental governance expenditure is 0.0664 and 0.0283, respectively, confirming that both are important to the role that LCPP plays; (3) at 5% significance level, the exogenous policy effect of the LCPP on urban green innovation efficiency is more obvious in cities with a larger population size and higher degree of development, whose pillar industry is heavy industry.

On multi-type Cannings models and multi-type exchangeable coalescents

A multi-type neutral Cannings population model with migration and fixed subpopulation sizes is analyzed. Under appropriate conditions, as all subpopulation sizes tend to infinity, the ancestral process, properly time-scaled, converges to a multi-type coalescent sharing the exchangeability and consistency property. The proof gains from coalescent theory for single-type Cannings models and from decompositions of transition probabilities into parts concerning reproduction and migration respectively. The following section deals with a different but closely related multi-type Cannings model with mutation and fixed total population size but stochastically varying subpopulation sizes. The latter model is analyzed forward and backward in time with an emphasis on its behavior as the total population size tends to infinity. Forward in time, multi-type limiting branching processes arise for large population size. Its backward structure and related open problems are briefly discussed.

Acute disseminated encephalomyelitis and transverse myelitis following COVID-19 vaccination – A self-controlled case series analysis

Acute Disseminated Encephalomyelitis (ADEM) and Transverse Myelitis (TM) are within the group of immune mediated disorders of acquired demyelinating syndromes. Both have been described in temporal association following various vaccinations in case reports and case series and have been evaluated in observational studies. A recent analysis conducted by The Global Vaccine Data Network (GVDN) observed an excess of ADEM and TM cases following the adenoviral vectored ChAdOx1 nCoV-19 (AZD1222) and mRNA-1273 vaccines, compared with historically expected background rates from prior to the pandemic. Further epidemiologic studies were recommended to explore these potential associations.We utilized an Australian vaccine datalink, Vaccine Safety Health-Link (VSHL), to perform a self-controlled case series analysis for this purpose. VSHL was selected for this analysis as while VSHL data are utilised for GVDN association studies, they were not included in the GVDN observed expected analyses. The VSHL dataset contains vaccination records sourced from the Australian Immunisation Register, and hospital admission records from the Victorian Admitted Episodes Dataset for 6.7 million people. These datasets were used to determine the relative incidence (RI) of G040 (ADEM) and G373 (TM) ICD-10-AM coded admissions in the 42-day risk window following COVID-19 vaccinations as compared to control periods either side of the risk window.We observed associations between ChAdOx1 adenovirus vector COVID-19 vaccination and ADEM (all dose RI: 3.74 [95 %CI 1.02,13.70]) and TM (dose 1 RI: 2.49 [95 %CI: 1.07,5.79]) incident admissions. No associations were observed between mRNA COVID-19 vaccines and ADEM or TM. These findings translate to an extremely small absolute risk of ADEM (0.78 per million doses) and TM (1.82 per million doses) following vaccination; any potential risk of ADEM or TM should be weighed against the well-established protective benefits of vaccination against COVID-19 disease and its complications.This study demonstrates the value of the GVDN collaboration leveraging large population sizes to examine important vaccine safety questions regarding rare outcomes, as well as the value of linked population level datasets, such as VSHL, to rapidly explore associations that are identified.

The weak genetic structure of Melolontha melolontha (L.) and Melolontha hippocastani (Fabr.), two important forest pests, indicates their large population sizes and effective gene flow

Abstract Cockchafers Melolontha spp. are polyphagous root pests and outbreak species of considerable economic importance to forestry in Europe. Knowledge of genetic diversity within and between cockchafer populations is largely unexplored but could lead to more effective monitoring and management strategies of these pests. In this study, we fill several gaps in the knowledge of the genetic population structure of Melolontha melolontha and Melolontha hippocastani. Using microsatellite loci and over 200 individuals per species, we examined the genetic structure of Melolontha spp. populations collected from three primary outbreak areas in central and southeastern Poland. We demonstrated that our focal species share some common genetic patterns, such as considerable genetic diversity within subpopulations (within sampling sites) with minor effects of past bottlenecks possibly masked by current population sizes. The estimates of effective population sizes, although subject to wide credibility intervals, indicated a large number of individuals contributing to further generations of the population. The migration rates exceed the threshold of one per generation required for gene flow and maintenance of population equilibrium, indicating limited impact from forest management practices on either cockchafer species. While genetic differentiation was observed in M. melolontha populations, supported by various indices (fixation index, principal coordinate analysis, assignment tests), the M. hippocastani populations were genetically similar. This disparity may hint at the potential historical divergence between these species. In this aspect, more detailed phylogeographic and population genetic studies covering a large area of the Palaearctic distributions of both species are required. Our findings constitute one of the initial efforts aimed at delineating the genetic diversity, differentiation, population structure, gene flow, and migration patterns within Melolontha spp. This exploration is especially significant for M. hippocastani, given its completely unexplored genetic population structure.

Omniflow® II biosynthetic graft offers acceptable early and mid-term outcomes in redo surgery in patients with critical limb-threatening ischemia with no available autologous vein material.

In this study, the early and mid-term outcomes of Omniflow® II (LeMaitre Vascular, Inc., Burlington, MA, USA) biosynthetic graft in redo surgery in patients with critical limb-threatening ischemia (CLTI) with no available autologous vein material were investigated with the aim to compare the outcomes obtained in "de novo" surgery versus redo surgery. From January 2018 until December 2022, data of CLTI patients from 18 centers in Italy with no autologous vein material underwent infrainguinal bypass with Omniflow® II biosynthetic graft were collected. Thirty-day outcome measures including intraoperative technical success, major morbidity, mortality, and graft patency were assessed and compared. At two-year follow-up, estimated outcomes of survival, primary patency, primary assisted patency, secondary patency, freedom from reintervention, and amputation-free survival were analyzed using Kaplan-Meier curves and compared between groups using the log-rank test. In the study period 119 CLTI patients had an infrainguinal bypass with Omniflow® II biosynthetic graft. Seventy-seven patients (64.7%) underwent bypass as "de novo" treatment (group de novo), whilst in the remaining 42 patients (35.3%) the procedure was performed as redo surgery due to occlusion and/or infection of a previous bypass graft (group redo). Two groups were homogeneous in terms of demographic, clinical, and morphological data. In group redo explantation of an infected prosthetic graft was needed in 4 cases (9.5%). Intraoperative technical success was achieved in all cases in both groups. At 30 days, the overall patency rate did not differ between the two groups (69/77, 89.6%, group de novo vs. 35/42, 83.3%, group redo; P=0.24), whilst in group redo limb loss was higher with a statistically significant different 30-day major amputation rate between the two groups (11.9% group redo vs. 1.3% group de novo; P<0.001). Overall median duration of follow-up was eight months (IQR 6-13). At two-year follow-up there were no differences between the two groups in terms of survival (67.7% group de novo vs. 55.8% group redo, P=0.53), primary patency (34.4% group de novo vs. 26.8% group redo, P=0.25), primary assisted patency (43.6% group de novo vs. 28.8% group redo, P=0.12), freedom from reintervention (64.1% group de novo vs. 68.8% group redo, P=0.98), and amputation-free survival (67.8% group de novo vs. 60% group redo, P=0.12). Secondary patency was significantly higher in group de novo (53.7% vs. 32.3%, P=0.05). During the follow-up, the overall rates of graft infection and aneurysmal degeneration were 3.4%, and 0.8%, respectively. Nevertheless, poorer early outcomes in terms of limb salvage, Omniflow® II biosynthetic graft offers acceptable ywo-year outcomes in redo surgery in CLTI patients with no available autologous vein material. Further studies with larger population sizes are needed to validate these outcomes.

HAND GRIP STRENGTH IS ASSOCIATED WITH CLINICAL SYMPTOM BURDEN IN CROHN'S DISEASE

Abstract INTRODUCTION Inflammatory bowel disease (IBD) is a chronic inflammatory condition that may result in malnutrition and alteration of body composition, such as the development of sarcopenia. Sarcopenia is a known component of frailty, which is a driver of poor health outcomes and a significant independent predictor of mortality in patients with IBD. The purpose of this study was to determine whether grip strength, as a predictor of sarcopenia and frailty, is associated with clinical symptoms, endoscopic disease activity and disease-related disability in patients with IBD. METHODS This is a prospective cohort study performed at a single tertiary care center. Outpatient adults aged 18 to 89-years-old with a diagnosis of ulcerative colitis (UC) or Crohn’s disease (CD), were consented and enrolled at the time of an outpatient colonoscopy. Study participants were asked to complete two paper surveys addressing clinical symptoms and IBD Disability Index. Grip strength measurements were obtained using a Jamar dynamometer and adjusted for age and sex by Z-score calculation. RESULTS There was a total of 74 patients, with a mean age of 47.06 years, 51.4% male and 48.6% female with a diagnosis of either UC (38%) or CD (62%). The mean disease duration was 15.7 years (0.5-50.7). Mean hand grip Z-score amongst all patients was lower in patients not in clinical remission compared to those in clinical remission (–0.160 vs 0.480, p = 0.025), though in subgroup analysis based on diagnosis, statical significance only maintained in the CD, but not the UC group (-0.230 vs 0.610, p=0.044; 0.020 vs 0.340, p=0.544 respectively). Mean hand grip Z-score was not associated with IBD Disability Index (–0.070 vs 0.250, p= 0.669) or endoscopic disease activity (UC 0.210 vs 0.070, p=0.513; CD –0.108 vs 0.274, p=0.638). CONCLUSION Low hand grip strength is associated with clinical disease activity in patients with CD but not UC. Our study does not suggest hand grip strength to be associated with IBD-related disability or endoscopic disease activity in either patients with UC or CD. Data on clinical outcomes at 6-months will be collected. DISCUSSION From the findings in our study, hand grip measurements alone may not be the best predictor of disease activity or related disability. There is a lack of validated diagnostic criteria for sarcopenia and frailty in the IBD population and additional diagnostic modalities may be required. While our study suggests that hand grip may be correlated with clinical disease activity in patients with CD, additional studies with a large population size and wider representation of disease severity, such as including hospitalized IBD populations, are needed to further validate these findings.

Anatomical Dimensions and Types of the Anterior Clinoid Process in Libyan population by Using Computed Tomography: A cross Sectional Study

The anterior clinoid process (ACP) has a complex anatomical feature and surrounded by important structures which may complicate the surgical procedures during the anterior clinoidectomy. Our objective was to measure dimensions of anterior clinoid process, and to determine variations of its types. Forty-nine of cranial computed tomography scans were performed from adult Libyan patients on routine examination of paranasal sinus at Benghazi Medical Center between February 1, 2023, and April 14, 2023. The right and left ACP length and the base width were measured on the axial CT images. Data analysis was done using SPSS version 23. The means and standard deviations were calculated. The paired Student’s t test was used to determine the statistically significant differences in means between the right and left ACP. (P ≤ 0.05) was considered statistically significant at (95%) confidence interval. The length of the right and left ACPs were 11.2 ± 2.2 mm and 11.6 ± 2.4mm, respectively. The width of the right and left ACPs were 5.37± 1.22 mm and 5.42 ± 1.24mm, respectively. Type 2 anterior clinoid process was the commonest (75.5 %) while type 1 was the least common (4.1 %). There was no statistically significant difference between right and left sided measurements. Our study outcomes may be helpful for pre-operative planning. Presence of any variations may result in unnecessary injury to the complicated surgical procedures that involve removal of ACPs. Further research studies required with large sample size of population will give well understanding about the parameter of ACPs.