Predictive value of changes in the level of carbohydrate antigen 19-9 in patients with locally advanced rectal cancer treated with neoadjuvant chemoradiotherapy

AIM

The aim of this work was to explore the predictive value of changes in the level of carbohydrate antigen 19-9 (CA19-9) after neoadjuvant chemoradiotherapy (nCRT) and after surgery in patients with locally advanced rectal cancer (LARC).

METHOD

Patients with LARC who underwent nCRT and radical surgery (between 2011 and 2016) were divided into three groups according to pre-nCRT and post-nCRT CA19-9 levels as follows: normal pre-nCRT CA19-9 (normal CA19-9 group), elevated pre-nCRT and normal post-nCRT CA19-9 (normalized group) and elevated pre-nCRT and elevated post-nCRT CA19-9 (nonnormalized group). The pathological nCRT response criteria included ypCR and downstaging (ypStages 0-I). Recurrence-free survival (RFS) and overall survival (OS) were analysed.

RESULTS

A total of 721 patients were identified. The normal CA19-9 group was significantly associated with ypCR (n = 159) and downstaging (n = 347) (P < 0.05). The normalized group (n = 76) had worse RFS and OS than the normal CA19-9 group (n = 622) and better RFS and OS than the nonnormalized group (n = 23) (5-year RFS 47.0% vs 66.9% vs 81.5%, P < 0.001; 5-year OS 47.0% vs 75.4% vs 85.0%, P < 0.001). In multivariate analysis, CA19-9 group and ypTNM stage were independent predictors of RFS and OS. Moreover, for the 23 patients with elevated post-nCRT CA19-9 levels, the RFS and OS of patients with normalized postoperative CA19-9 levels were significantly better than those of patients with elevated postoperative CA19-9 levels (P < 0.05).

CONCLUSION

Following nCRT, changes in the CA19-9 level are a strong prognostic marker for long-term survival, and they may be helpful in the selection of patients who prefer more conservative surgery after chemoradiotherapy.

[Study of methylation of mitochondrial MT-COI of benzene poisoning]

Objective: To research the mitochondrial cytochrome c oxidase subunit I (MT-COI) gene methylation levels in patients with occupational chronic benzene poisoning, and to explore effective molec μlar biomarkers in patients with occupational chronic benzene poisoning. Methods: 38 confirmed cases of occupational chronic benzene poisoning were selected in the case group. 46 healthy people who underwent physical in our hospital were selected in the control group. Pyrosequencing was used to detect the methylation sites of methylation sites, flow cytometry was used to detect peripheral blood cell count levels, and non-parametric statistical methods were used to analyze the differences in detection results between the two groups. Results: The methylation level of mitochondrial MT-COI site 1 (2.21±0.81) % in the case group was less than that in the control group, and the difference was statistically significant (P<0.05) . The methylation level of mitochondrial MT-COI site 2 (2.31±0.96%) in the case group was less than that in the control group, and the difference was statistically significant (P<0.05) . The methylation average level of mitochondrial MT-COI (2.26±0.75) % in the case group was less than that in the control group, and the difference was statistically significant (P<0.05) . Analysis of the average level of methylation found that the methylation level of mitochondrial MT-COI was correlated with WBC (P<0.05) . Analysis of the average level of methylation found that the methylation level of mitochondrial MT-COI was correlated with platelets (r=0.254、0.280, P<0.05) . Conclusion: The level of mitochondrial MT-COI gene methylation in patients with occupational chronic benzene poisoning may be related to the sensitivity to benzene exposure. Mitochondrial MT-COI gene methylation may serve as a potential predictive biomarker for benzene poisoning.

Cloud-cloud collision as drivers of the chemical complexity in Galactic Centre molecular clouds

G+0.693-0.03 is a quiescent molecular cloud located within the Sagittarius B2 (Sgr B2) star-forming complex. Recent spectral surveys have shown that it represents one of the most prolific repositories of complex organic species in the Galaxy. The origin of such chemical complexity, along with the small-scale physical structure and properties of G+0.693-0.03, remains a mystery. In this paper, we report the study of multiple molecules with interferometric observations in combination with single-dish data in G+0.693-0.03. Despite the lack of detection of continuum source, we find small-scale (0.2 pc) structures within this cloud. The analysis of the molecular emission of typical shock tracers such as SiO, HNCO, and CH₃OH unveiled two molecular components, peaking at velocities of 57 and 75 km s^-1. They are found to be interconnected in both space and velocity. The position-velocity diagrams show features that match with the observational signatures of a cloud-cloud collision. Additionally, we detect three series of class I methanol masers known to appear in shocked gas, supporting the cloud-cloud collision scenario. From the maser emission we provide constraints on the gas kinetic temperatures (∼30-150 K) and H₂ densities (10⁴-10⁵ cm^-2). These properties are similar to those found for the starburst galaxy NGC253 also using class I methanol masers, suggested to be associated with a cloud-cloud collision. We conclude that shocks driven by the possible cloud-cloud collision is likely the most important mechanism responsible for the high level of chemical complexity observed in G+0.693-0.03.

[Optimization of ATG dose in haploid hematopoietic stem cell transplantation for hematologic malignancies]

Objective: To compare the clinical efficacy of different doses of rabbit antithymocyte globulin (rATG) in haplo-HSCT in the treatment of hematologic malignancies. Methods: Malignant hematological patients treated at our hospital from March 2013 to December 2018 were retrospectively analyzed. These patients were divided into three groups as per three doses of ATG (6 mg/kg, 7.5 mg/kg, and 9 mg/kg) in the conditioning regimens. The transplant outcomes were compared in terms of the occurrence of acute graft versus host disease (GVHD) , infection, and survival. Results: ①Total 288 patients were enrolled in the study, including 182 men and 106 women, with a median age of 18 (6-62) years. Total 110 patients were diagnosed with acute lymphoblastic leukemia (ALL) , 128 with acute myelogenous leukemia (AML) , 8 with chronic myeloid leukemia (CML) , 28 with myelodysplastic syndrome (MDS) , and 14 with mixed cell leukemia (MAL) . There were 159 patients in the ATG-6 group, 72 in the ATG-7.5 group, and 57 in the ATG-9 group. The median follow-up time of post transplantation was 14 (0.2-74) months. ②The incidence of neutrophil engraftment (96.9% , 97.2% , and 96.5% , respectively) and platelet engraftment (92.5% , 87.5% , and 86% , respectively) did not significantly differ among the ATG-6, ATG-7.5, and ATG-9 groups (P=0.972, P=0.276) . The incidence of grades 2-4 acute GVHD was 14.5% , 11.1% , and 8.8% in the three groups, respectively (P=0.493) , chronic GVHD incidence in the three group was 8.8% , 14.3% and 12.0% , respectively (P=0.493) . The infection rates of CMV and EBV in the ATG-9 group (77.2% and 12.5% ) were significantly higher than those in the ATG-6 (43.3% and 3.5% ) , and ATG -7.5 group (44.4% and 1.5% ) (P<0.001 and P=0.033, respectively) . ③Among the three groups, there were no significant difference in the 3-year overall survival [68.5% (95% CI 60.3% -77.9% ) , 60.1% (95% CI 48.3% -74.8% ) , 64.7% (95% CI 51.9% -80.7% ) ], cumulative incidences of relapse [34.6% (95% CI 34.3% -35.1% ) , 38.0% (95% CI 37.3% -38.7% ) , 20.6% (95% CI 20.0% -21.3% ) ], disease-free survival [53.3% (95% CI 44.9% -63.4% ) , 51.9% (95% CI 41% -65.8% ) , 63.9% (95% CI 51.9% -78.7% ) ] and non-relapse mortality [24.2% (95% CI 23.8% -24.5% ) , 26.0% (95% CI 25.4% -26.6% ) , 23.6% (95% CI 26.3% -28.2% ) ] (P=0.648, P=0.165, and P=0.486 and P=0.955) . Conclusion: Low dose (6 mg/kg) of rATG may increase the risk of grade Ⅱ-Ⅳ aGVHD, and a high dose (9 mg/kg) of ATG could significantly increase the risk of CMV and EBV infection. Median dose (7.5 mg/kg) of ATG is expected to reduce the incidence of moderate to severe aGVHD and viral infections without increasing the mortality.

Mesorectal fat area and mesorectal area affect the surgical difficulty of robotic-assisted mesorectal excision and intersphincteric resection respectively in different ways

AIM

Many studies have demonstrated predictors of the difficulty of laparoscopic anterior resection for rectal cancer. Few studies focus on the influence of pelvic dimensions on robotic-assisted mesorectal excision (ME) and intersphincteric resection (ISR). This study aimed to evaluate the influences of the mesorectal fat area (MFA) and mesorectal area on the difficulty of robotic sphincter-saving surgery.

METHODS

We included 156 patients with middle and low rectal cancer who underwent robotic sphincter-saving surgery. Clinical and anatomical factors, including the pelvic dimensions, were collected. Linear regression was performed for variables associated with surgical duration. We also performed subgroup analyses for robotic-assisted ME and ISR. Logistic regression was used to find variables associated with transanal dissection.

RESULTS

For patients with middle or low rectal cancer, the sacral length and tumour distance from the anal verge were independently associated with surgical duration. The pT stage, sacral length and the MFA were independent predictors for the surgical duration of robotic-assisted ME. By contrast, a small mesorectal area was independently related to a longer duration of robotic-assisted ISR. The pelvic outlet length was independently associated with the use of transanal dissection for ISR.

CONCLUSION

It is suggested that a large MFA could affect the difficulty of ME in robotic-assisted ME, while a small mesorectal area could increase the surgical difficulty of robotic-assisted ISR for low rectal cancer. Besides, the pelvic outlet length was associated with the use of transanal dissection. Further studies are needed to validate the results and draw more scientific conclusions.

The Ca2+ -regulated protein kinase CIPK1 integrates plant responses to phosphate deficiency in Arabidopsis thaliana

Phosphate (Pi) deficiency severely restricts plant growth and development, as Pi is an essential macronutrient. Calcium (Ca²⁺ ) is a ubiquitous second messenger in plants; calcineurin B-like proteins (CBL) and CBL-interacting protein kinases (CIPK) are signalling pathways that act as an important Ca²⁺ signalling network which integrates plants to fine tune the response to stress; however, whether CIPK are involved in Pi deficiency stress remains largely unknown. In this study, we carried out a reverse genetic strategy to screen T-DNA insertion mutants of CIPK isoforms under Pi deficiency in Arabidopsis thaliana. Then Pi content, transcription of phosphate starvation-induced (PSI) genes, acid phosphatase activity and hydrogen peroxide were determined in the wild-type (WT) and cipk1 mutant, respectively. The phenotype of CIPK1 complementation lines was analysed. The cipk1 mutant had a more sensitive phenotype, with lower root elongation and root length, and decreased Pi content compared with the WT under Pi deficiency. Moreover, CIPK1 mutation caused phosphate starvation-induced (PSI) genes to be significantly induced under Pi deficiency. Histological staining demonstrated that the cipk1 mutant had increased acid phosphatase activity and hydrogen peroxide concentration under Pi deficiency. By using the yeast two-hybrid system, we further demonstrated the interaction between CIPK1 and the WRKY transcription factors, WRKY6 and WRKY42. Overall, we demonstrate that CIPK1 is involved in the Pi deficiency signalling pathway in A. thaliana, revealing the important role of Ca²⁺ in the Pi nutrition signalling pathway, and potentially providing a theoretical foundation for molecular breeding of crops with better Pi utilization efficiency.

Intussusception in 2 Children With Severe Acute Respiratory Syndrome Coronavirus-2 Infection

We note that intussusception was likely associated with severe acute respiratory syndrome coronavirus-2 infection in 2 infants in Wuhan and London. The intussusception was reduced by enemas in Wuhan; the outcome was fatal. The intussusception was not reduced by enemas in London and required surgery; the outcome was favorable.

Cerebral tissue pO2 response to treadmill exercise in awake mice

We exploited two-photon microscopy and Doppler optical coherence tomography to examine the cerebral blood flow and tissue pO₂ response to forced treadmill exercise in awake mice. To our knowledge, this is the first study performing both direct measure of brain tissue pO₂ during acute forced exercise and underlying microvascular response at capillary and non-capillary levels. We observed that cerebral perfusion and oxygenation are enhanced during running at 5 m/min compared to rest. At faster running speeds (10 and 15 m/min), decreasing trends in arteriolar and capillary flow speed were observed, which could be due to cerebral autoregulation and constriction of arterioles in response to blood pressure increase. However, tissue pO₂ was maintained, likely due to an increase in RBC linear density. Higher cerebral oxygenation at exercise levels 5–15 m/min suggests beneficial effects of exercise in situations where oxygen delivery to the brain is compromised, such as in aging, atherosclerosis and Alzheimer Disease.

AB0053 BERGENIN, ACTING AS AN AGONIST OF SIRT1, REDUCE SERUM URATE IN MICE THROUGH THE UPREGULATION OF ABCG2

Background:

About 20% of individuals in the USA have asymptomatic hyperuricaemia[1]. However, Urate-lowering therapy in asymptomatic hyperuricaemia condition is still controversial considering the benefit and side effects[2]. Therefore, safe and effective anti-hyperuricemia therapies are necessary.

Objectives:

Bergenin, the major bioactive ingredient isolated from Saxifraga stolonifera, could activate SIRT1. In this study, we identify the effect of bergenin on hyperuricemia, and explored the related mechanisms.

Methods:

Significant hyperuricemia was established in C57BL/6N mice treated with oxonate and yeast polysaccharide. Bergenin was administered to the mice at the same time. The serum uric acid and creatinine levels, clearance of uric acid and creatinine, the intestinal uric acid excretion, and renal pathological lesions were determined were used to evaluate the anti-hyperuricemic effects. The location and expression levels of ABCG2 in the kidney and intestine were analyzed. HK-2 and Caco-2 cell lines were exposed to soluble uric acid with or without the treatment of Bergenin. Then the expression of ABCG2 and underlying mechanisms were explored.

Results:

The administration of bergenin decreased serum uric acid in hyperuricemic mice by the promotion of uric acid excretion both in kidney and intestine. Bergenin recued the downregulation of ABCG2 in the kidney of hyperuricemic mice and upregulated the expression of ABCG2 in the jejunum and ileum. In vitro, Bergenin significantly increased the expression of ABCG2 as well as activated SIRT1, which was reversed by addition of PPARg antagonist GW9662 and siPPARg.

Conclusion:

These findings suggest bergenin increases uric acid excretion both in the kidney and intestines, which may be related to the upregulation of ABCG2 via SIRT1- PPARg pathway.

References:

[1]Zhu, Y., Pandya, B. J. & Choi, H. K. Prevalence of gout and hyperuricemia in the US general population: the National Health and Nutrition Examination Survey 2007–2008. Arthritis Rheum. 63, 3136–3141 (2011).

[2]Joosten LAB, Crisan TO, Bjornstad P, Johnson RJ: Asymptomatic hyperuricaemia: a silent activator of the innate immune system. Nature reviews Rheumatology 2020, 16(2):75-86.

Disclosure of Interests:

None declared

AB0610 SEASONAL VARIATION IN IDIOPATHIC INFLAMMATORY MYOPATHIES INCIDENCE AND PRESENTATION: A RETROSPECTIVE STUDY IN BEIJING AND HONG KONG

Background:

Seasonal patterns of disease onset and severity in idiopathic inflammatory myopathies (IIMs) as a whole are conflicting [1-3]. In recent years, over 10 myositis-specific antibodies (MSAs) have been identified. They are able to divide patients into homogenous subgroups and inform on prognosis [4].

Objectives:

The objective of the study was to investigate the seasonal variation of onset of IIMs characterised serologically.

Methods:

This was a multi-centred retrospective observational study. Consecutive Chinese patients with IIMs admitted to the rheumatology wards of the participating major regional hospitals in Beijing and Hong Kong from July 2013 to June 2018 were recruited. The diagnosis of IIMs was based on the Bohan and Peter’s criteria with definite or probable cases being included [5]. Patients with clinically amyopathic disease must have the typical Gottron’s papules or heliotrope rash as determined by rheumatologists or dermatologists, and with no symptoms or signs of muscle involvement according to Sontheimer [6]. Patients with juvenile myositis, inclusion body myositis, cancer-associated myositis and myositis associated with other connective tissue disease were excluded. A commercial line blot immunoassay kit (EUROLINE) was used to detect the MSAs.

Results:

All together 495 patients were studied. The mean age of the patients at disease onset was 48.1 years (S.D. 13.3). There was a female predominance (68.3%). The subgroups of IIMs were: dermatomyositis (61.0%), polymyositis (21.8%), clinically amyopathic dermatomyositis (12.9%), immune mediated necrotising myopathy (3.8%) and nonspecific myositis (0.4%). No particular seasonal pattern in disease onset was observed in IIM patients as a whole (Figure 1) or in any classical subgroups. However, significantly more patients with any one MSA had their disease started in the first half of the year (p=0.007) as shown in Figure 2. Patients with either anti-synthetase or anti-MDA5 antibodies, which are associated with interstitial lung disease, had more frequent disease onset from November to February, which might coincide with the local flu season. It was also found that MSA positivity was associated with infection of the patient (p=0.005). Further analyses showed that patients with MSAs which are typically associated with severe skin disease (MDA5, TIF1g, NXP2, SAE) had more hospitalisation from April to September where excessive sun exposure is expected. There were no major differences between the Beijing and Hong Kong subgroups.

Conclusion:

Apparent seasonal patterns were noticed in our ethno-serologically defined IIM patients. Certain environmental factors, particularly infection or UV exposure, could be potential triggers. Our findings could shed light on the identification of etiologic factors and enhance our understanding of disease pathogenesis.

References:

[1]Manta P, Kalfakis N, Vassilopoulos D. Evidence for Seasonal Variation in Polymyositis. Neuroepidemiology 1989;8:262–265.

[2]Phillips BA, Zilko PJ, Garlepp MJ, et al. Seasonal occurrence of relapses in inflammatory myopathies: a preliminary study. J Neurol 2002;249:441–4.

[3]Lefe R, Burgess S, Miller F, et al. Distinct Seasonal Pattern in The Onset of Adult Idiopathic Inflammatory Myopathy in Patients with Auto Antibodies Anti-Jo-1 and Anti-Signal Recognition particle. Arthritis and Rheumatism 1991;34(11):1391-1396.

[4]Tansley SL, Betterridge ZE, McHugh NJ. The diagnostic utility of autoantibodies in adult and juvenile myostis. Curt Opin Rheumatol 2013;25(6):772-777.

[5]Bohan A, Peter JB. Polymyositis and dermatomyositis. N Engl J Med 1975;292:344-347.

[6]Sontheimer RD. Clinically myopathic dermatomyositis: what can we now tell our patients? Arch Dermatol 2010;146(1):76-80.

Disclosure of Interests:

None declared

Microstructure, mechanical property and corrosion behavior of porous Ti-Ta-Nb-Zr

In this paper, biomedical porous Ti–Nb–Ta–Zr with 40% porosity and 166 ± 21 μm macro-pore size was successfully fabricated by space holder method. The microstructure, Vickers hardness, compressive and electrochemistry behavior were studied. It results that a few second phases exist in β matrix of the porous Ti–Nb–Ta–Zr. Its Young's modulus is 0.8 GPa, close to 0.01–3 GPa for trabecular bone. The total recovery strain ratio and pseudoelastic strain ratio are 8.8% and 2.7%, respectively. It fails mainly by brittle cleavage with the fan-shaped and smooth cleaved facets. Although, local ductile fracture by a few dimples and a small amount of transcrystalline fracture with the cleavage of similarly oriented laths in a colony are observed on the fracture surface. The impedance spectrum of porous Ti–Nb–Ta–Zr has the characteristics of half capacitive arc resistance, showing good corrosion resistance in SBF solution.

•

Porous Ti–Nb–Ta–Zr alloy with mainly β phase was fabricated by space holder method.

•

Porous Ti alloy with 40% porosity and 166 ± 21 μm macro-pore size failed by brittle cleavage.

•

The total recovery strain ratio and pseudoelastic strain ratio are 8.8% and 2.7%, respectively.

•

The Young's modulus of porous TNTZ is 0.8 GPa, close to trabecular bone.

•

The impedance spectrum of porous TNTZ shows good corrosion resistance in SBF solution.

Racial disparity of Crouzon syndrome in maxilla and mandible

The racial disparity of facial features in craniosynostosis patients is not fully understood. The aim of this study was to explore the difference in maxillary and mandibular morphology and spatial position in Asian and Caucasian Crouzon syndrome patients. Ninety-one computed tomography scans were included (12 Asian Crouzon syndrome patients, 22 Asian controls; 16 Caucasian Crouzon syndrome patients, 41 Caucasian controls) and measured using Materialise software. The maxillary and mandibular volumes of Asian patients were both reduced by 19% (P=0.102 and P=0.187), and those of Caucasian patients were reduced by 15% (P=0.142) and 14% (P=0.211) when compared to the respective race-specific controls. Maxilla length of Asian patients was reduced by 6.36mm (14%, P=0.003), while the reduction in Caucasian patients was 4.88mm (10%, P=0.038). ANS was retracted 11.99mm (P<0.001) in Asian patients and 11.54mm (P<0.001) in Caucasian patients. The ANB angle was narrowed by 13.17° (P<0.001) in Asian patients compared to Asian controls, and by 7.02° (P<0.001) in Caucasian patients compared to Caucasian controls. The retrusive midface profiles of Asian and Caucasian Crouzon syndrome look similar; both result from the combined effect of hypoplastic size and backward displacement. However, the insufficiency was found to be more a failure of the anteroposterior maxillary length in Asian patients, and more due to posterior maxillary positioning in Caucasian patients. Therefore, prognathism in Crouzon syndrome patients is more likely caused by displacement rather than elongation of mandibular length in both races. Crouzon syndrome results in the same extent of overall volume deficiency of the maxilla and mandible in these races.

Search for Electron Antineutrino Appearance in a Long-Baseline Muon Antineutrino Beam

Electron antineutrino appearance is measured by the T2K experiment in an accelerator-produced antineutrino beam, using additional neutrino beam operation to constrain parameters of the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing matrix. T2K observes 15 candidate electron antineutrino events with a background expectation of 9.3 events. Including information from the kinematic distribution of observed events, the hypothesis of no electron antineutrino appearance is disfavored with a significance of 2.40σ and no discrepancy between data and PMNS predictions is found. A complementary analysis that introduces an additional free parameter which allows non-PMNS values of electron neutrino and antineutrino appearance also finds no discrepancy between data and PMNS predictions.

A transition of ω-Fe3C → ω'-Fe3C → θ'-Fe3C in Fe-C martensite

Carbon steel is strong primarily because of carbides with the most well-known one being θ-Fe₃C type cementite. However, the formation mechanism of cementite remains unclear. In this study, a new metastable carbide formation mechanism was proposed as ω-Fe₃C → ω′-Fe₃C → θ′-Fe₃C based on the transmission electron microscopy (TEM) observation. Results shown that in quenched high-carbon binary alloys, hexagonal ω-Fe₃C fine particles are distributed in the martensite twinning boundary alone, while two metastable carbides (ω′ and θ′) coexist in the quenched pearlite. These two carbides both possess orthorhombic crystal structure with different lattice parameters (a_θ′ = a_ω′ = a_ω = \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sqrt{2}$$\end{document}2a_α-Fe = 4.033 Å, b_θ′ = 2 × b_ω′ = 2 × c_ω = \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sqrt{3}$$\end{document}3a_α-Fe = 4.94 Å, and c_θ′ = c_ω′ = \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sqrt{3}$$\end{document}3a_ω = 6.986 Å for a_α-Fe = 2.852 Å). The θ′ unit cell can be constructed simply by merging two ω′ unit cells together along its b_ω′ axis. Thus, the θ′ unit cell contains 12 Fe atoms and 4 C atoms, which in turn matches the composition and atomic number of the θ-Fe₃C cementite unit cell. The proposed theory in combination with experimental results gives a new insight into the carbide formation mechanism in Fe-C martensite.

Longitudinal optical coherence tomography imaging of tissue repair and microvasculature regeneration and function after targeted cerebral ischemia

SIGNIFICANCE

Understanding how the brain recovers from cerebral tissue and vascular damage after an ischemic event can help develop new therapeutic strategies for the treatment of stroke.

AIM

We investigated cerebral tissue repair and microvasculature regeneration and function after a targeted ischemic stroke.

APPROACH

Following photothrombosis occlusion of microvasculature, chronic optical coherence tomography (OCT)-based angiography was used to track ischemic tissue repair and microvasculature regeneration at three different cortical depths and up to 28 days in awake animals. Capillary network orientation analysis was performed to study the structural pattern of newly formed microvasculature. Based on the time-resolved OCT-angiography, we also investigated capillary stalling, which is likely related to ischemic stroke-induced inflammation.

RESULTS

Deeper cerebral tissue was found to have a larger ischemic area than shallower regions at any time point during the course of poststroke recovery, which suggests that cerebral tissue located deep in the cortex is more vulnerable. Regenerated microvasculature had a highly organized pattern at all cortical depths with a higher degree of structural reorganization in deeper regions. Additionally, capillary stalling event analysis revealed that cerebral ischemia augmented stalling events considerably.

CONCLUSION

Longitudinal OCT angiography reveals that regenerated capillary network has a highly directional pattern and an increased density and incidence of capillary stalling event.