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Journal of Neurosurgical Sciences Mar 2016The availability of flow diverters and new endovascular techniques has greatly reduced the need and indications for bypass surgery. Nevertheless, there are situations... (Review)
Review
The availability of flow diverters and new endovascular techniques has greatly reduced the need and indications for bypass surgery. Nevertheless, there are situations where a bypass is the best option for a complex cerebrovascular problem. Generally, typical indications are giant aneurysms with a wide neck and/or partially calcified aneurysms with main branches or perforating arteries arising directly from the sac or from the neck itself, or fusiform aneurysms, partially calcified aneurysms. In this paper we discuss the following issues as they apply to the modern use of bypass techniques. In case of fusiform aneurysms involving the proximal bifurcations of the media or the internal carotid artery combined and coordinated evaluations and efforts by a team which includes neurosurgeons and endovascular specialists is essential. Treatment with bypass alone may not be sufficient and the combination of one or more bypasses with an endovascular treatment of occlusion, partial aneurysm embolization or flow diversion may be the best strategy. Addressing complex and fusiform aneurysm surgery requires a problem solving attitude and in this lies both the challenging and the fun side of this surgery.
Topics: Cerebral Revascularization; Humans; Intracranial Aneurysm
PubMed: 26947783
DOI: No ID Found -
Journal of Vascular Surgery Apr 2022Much research remains focused on tibial bypass conduit selection. We sought to describe long-term amputation-free survival (AFS) and primary patency (PP) of patients...
OBJECTIVE
Much research remains focused on tibial bypass conduit selection. We sought to describe long-term amputation-free survival (AFS) and primary patency (PP) of patients undergoing tibial bypass by conduit type and configuration across several permutations in the Society for Vascular Surgery Vascular Quality Initiative.
METHODS
Patients in the Vascular Quality Initiative registry undergoing elective first-time femoral- or popliteal-to-tibial bypass for occlusive disease involving rest pain or tissue loss were identified. Prior ipsilateral infrainguinal bypass or concomitant procedures were excluded. Outcomes of interest included patient AFS at 22 months and PP at 1 year (defined as freedom from revision, thrombectomy, or graft occlusion).
RESULTS
A total of 4192 bypasses were identified. The majority utilized great saphenous vein (GSV) (76.2%), followed by polytetrafluoroethylene (10.6%), nonautologous biologic (6.5%), composite (3.3%), arm vein (2.8%), and small saphenous vein (0.6%). Compared with all prosthetic and composite bypasses, vein grafts had the best AFS (76.4%; P < .0001) and PP (68.1%; P = .041). Of the single segment vein conduits, GSV bypasses had the best PP (69.1%) and arm vein the worst (60.2%). AFS and PP were similar between single-segment GSV orientations. Single-segment GSV bypasses exhibited better PP than multiple segment bypasses (69.1% vs 54.6%; P = .0016). PP was significantly better for polytetrafluoroethylene compared with nonautologous biologic (68.4% vs 51.2%; P = .0039). PP did not significantly differ between vein cuff for prosthetic bypass compared with no vein cuff (69.1% vs 59.7%; P = .091). PP was not significantly different between single-segment GSV and prosthetic grafts with vein cuff (69.1% vs 69.1%; P = .51). There were no significant differences in AFS comparing arm vein, prosthetic bypass with vein cuff, or composite grafts (67.2% vs 63.8% vs 59.3%; P = .092), as well as in PP (60.2% vs 69.1% vs 54.8%; P = .14).
CONCLUSIONS
Single-segment vein bypass was only marginally the most optimal conduit. Surprisingly, there may be more equipoise among conduit types, particularly in the absence of adequate GSV. Prosthetic grafts overall may not be as disadvantaged in the long term as initially thought, especially when compared with arm vein, as prosthetic bypass with vein cuff did not significantly differ in PP. Similarly, a composite conduit may not impact long-term outcomes. These data suggest that conduit choice may not impact outcomes to the degree previously thought and that other factors may have a greater impact than presumed, especially in conduit limited situations.
Topics: Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Humans; Ischemia; Polytetrafluoroethylene; Popliteal Artery; Retrospective Studies; Saphenous Vein; Treatment Outcome; Vascular Patency
PubMed: 34788646
DOI: 10.1016/j.jvs.2021.10.057 -
EJVES Vascular Forum 2020Popliteal entrapment syndrome results from extrinsic compression of the popliteal artery by the surrounding musculotendinous structures and is a rare cause of limb...
INTRODUCTION
Popliteal entrapment syndrome results from extrinsic compression of the popliteal artery by the surrounding musculotendinous structures and is a rare cause of limb ischaemia. The purpose of this report is to highlight potential mistakes in the management of popliteal entrapment.
REPORT
In 2000, a 23 year old man underwent a popliteal to popliteal artery bypass surgery for what was initially diagnosed as a traumatic popliteal artery thrombosis. After being initially lost to follow up for 13 years, this "unspecified traumatic" thrombosis led to several inappropriate endovascular and open procedures misinterpreted as being caused by late graft failure. These included thrombectomy, aneurysmorrhaphy, polytetrafluoroethylene covered stent graft, a redo femoropopliteal bypass, and bypass thrombolysis. The diagnosis was reached 19 years after the initial surgery, when the patient underwent a redo bypass using a retrogeniculate approach. An abnormal lateral insertion of the gastrocnemius muscle medial head, and its accessory slip, constricted the artery, and also involved the popliteal vein (Type V), thus explaining previous revascularisation failures. Surgery consisted of resecting the accessory slip and the aneurysmal bypass. The artery was reconstructed with the cephalic vein. The patient was discharged on clopidogrel 75 mg, with no further complication, and a patent bypass at six months. Based on post-operative imaging (duplex ultrasound and magnetic resonance imaging), with forced plantarflexion and dorsiflexion, asymptomatic popliteal entrapment was also present on the contralateral side.
DISCUSSION
The finding of an isolated popliteal artery lesion in a young individual should be considered to be caused by popliteal artery entrapment, unless proven otherwise. Definitive surgical release of the popliteal artery should be favoured over other strategies.
PubMed: 33078168
DOI: 10.1016/j.ejvsvf.2020.07.031 -
Nucleic Acids Research Nov 2000Error-free lesion bypass and error-prone lesion bypass are important cellular responses to DNA damage during replication, both of which require a DNA polymerase (Pol)....
Error-free lesion bypass and error-prone lesion bypass are important cellular responses to DNA damage during replication, both of which require a DNA polymerase (Pol). To identify lesion bypass DNA polymerases, we have purified human Polkappa encoded by the DINB1 gene and examined its response to damaged DNA templates. Here, we show that human Polkappa is a novel lesion bypass polymerase in vitro. Purified human Polkappa efficiently bypassed a template 8-oxoguanine, incorporating mainly A and less frequently C opposite the lesion. Human Polkappa most frequently incorporated A opposite a template abasic site. Efficient further extension required T as the next template base, and was mediated mainly by a one-nucleotide deletion mechanism. Human Polkappa was able to bypass an acetylaminofluorene-modified G in DNA, incorporating either C or T, and less efficiently A opposite the lesion. Furthermore, human Polkappa effectively bypassed a template (-)-trans-anti-benzo[a]pyrene-N:(2)-dG lesion in an error-free manner by incorporating a C opposite the bulky adduct. In contrast, human Polkappa was unable to bypass a template TT dimer or a TT (6-4) photoproduct, two of the major UV lesions. These results suggest that Polkappa plays an important role in both error-free and error-prone lesion bypass in humans.
Topics: 2-Acetylaminofluorene; Base Pair Mismatch; Base Sequence; Benzo(a)pyrene; Catalysis; DNA Adducts; DNA Damage; DNA-Directed DNA Polymerase; Guanine; Humans; Mutagenesis; Mutagens; Nucleotides; Proteins; Pyrimidine Dimers; Recombinant Fusion Proteins; Substrate Specificity; Templates, Genetic
PubMed: 11058110
DOI: 10.1093/nar/28.21.4138 -
European Journal of Vascular and... Jul 2011Compare the outcome of distal (bypass to the crural arteries) versus ultradistal (bypass to the pedal arteries) bypasses in patients with critical leg ischaemia (CLI). (Comparative Study)
Comparative Study
OBJECTIVES
Compare the outcome of distal (bypass to the crural arteries) versus ultradistal (bypass to the pedal arteries) bypasses in patients with critical leg ischaemia (CLI).
DESIGN
Retrospective analysis of prospectively collected data of patients with CLI undergoing infra-popliteal bypass surgery is performed.
MATERIALS AND METHODS
Patients undergoing infra-popliteal bypass at a single institution between 2004 and 2010 are included. Patency rates at 1-year and amputation-free survival at 12 and 48 months are analysed.
RESULTS
Two hundred and thirty bypasses were performed in 209 consecutive patients (156 men, median age; 76 years, range; 19-96 years). One hundred and seventy nine (78%) bypass were classified as distal and 51 (22%) as ultradistal. The incidence of diabetes mellitus was significantly higher in the ultradistal group (p=0.0025). At 1-year, the distal group primary, assisted-primary and secondary patency rates were 61.7%, 83.1% and 87.4% compared to 61.9%, 87.4% and 87.4% in the ultradistal group respectively. Amputation-free survival at 12 and 48 months was 82.9% and 61.5% in the distal group compared to 83.0% and 64.9% in the ultradistal group.
CONCLUSIONS
This study show that both distal and ultradistal bypass have comparable outcome regardless of the co-morbidities. The authors believe that elderly patients should be offered ultradistal bypass if indicated to avoid major amputation.
Topics: Adult; Age Factors; Aged; Aged, 80 and over; Amputation, Surgical; Arterial Occlusive Diseases; Chi-Square Distribution; Comorbidity; Critical Illness; Disease-Free Survival; Female; Humans; Ischemia; Kaplan-Meier Estimate; Limb Salvage; London; Lower Extremity; Male; Middle Aged; Patient Selection; Retrospective Studies; Risk Assessment; Risk Factors; Time Factors; Treatment Outcome; Vascular Grafting; Vascular Patency; Young Adult
PubMed: 21514854
DOI: 10.1016/j.ejvs.2011.03.016 -
Biotechnology Advances Nov 2022Metabolism has long been considered as a relatively stiff set of biochemical reactions. This somewhat outdated and dogmatic view has been challenged over the last years,... (Review)
Review
Metabolism has long been considered as a relatively stiff set of biochemical reactions. This somewhat outdated and dogmatic view has been challenged over the last years, as multiple studies exposed unprecedented plasticity of metabolism by exploring rational and evolutionary modifications within the metabolic network of cell factories. Of particular importance is the emergence of metabolic bypasses, which consist of enzymatic reaction(s) that support unnatural connections between metabolic nodes. Such novel topologies can be generated through the introduction of heterologous enzymes or by upregulating native enzymes (sometimes relying on promiscuous activities thereof). Altogether, the adoption of bypasses resulted in an expansion in the capacity of the host's metabolic network, which can be harnessed for bioproduction. In this review, we discuss modifications to the canonical architecture of central carbon metabolism derived from such bypasses towards six optimization purposes: stoichiometric gain, overcoming kinetic limitations, solving thermodynamic barriers, circumventing toxic intermediates, uncoupling product synthesis from biomass formation, and altering redox cofactor specificity. The metabolic costs associated with bypass-implementation are likewise discussed, including tailoring their design towards improving bioproduction.
Topics: Biomass; Carbon; Metabolic Engineering; Metabolic Networks and Pathways; Microbial Consortia; Oxidation-Reduction
PubMed: 36096403
DOI: 10.1016/j.biotechadv.2022.108035 -
Methods in Enzymology 2021DNA-peptide (DpCs) and DNA-protein cross-links (DPCs) are DNA lesions formed when polypeptides and nuclear proteins become covalently trapped on DNA strands. DNA-protein...
DNA-peptide (DpCs) and DNA-protein cross-links (DPCs) are DNA lesions formed when polypeptides and nuclear proteins become covalently trapped on DNA strands. DNA-protein cross-links are of enormous size and hence pose challenges to cell survival by blocking DNA replication, transcription, and repair. However, DPCs can undergo proteolytic degradation via various pathways to give shorter polypeptide chains (DpCs). The resulting DpC lesions are efficiently bypassed by translesion synthesis (TLS) DNA polymerases like κ, η, δ, etc., although polymerase bypass efficiency as well as correct base insertion depends heavily on size, sequence context, and position of peptides in DpCs. This chapter explores various synthetic methods to generate these lesions including detailed experimental procedures for the construction of DpCs and DPCs via reductive amination and oxime ligation. Further we describe biochemical experiments to investigate the effects of these lesions on DNA polymerase activity and fidelity.
Topics: DNA; DNA Damage; DNA Repair; DNA Replication; DNA-Directed DNA Polymerase; Peptides; Proteins
PubMed: 34776221
DOI: 10.1016/bs.mie.2021.09.005