Structural basis for control of secondary vessels in the long-finned eel, Anguilla reinhardtii

Histological sections of primary segmental arteries and associated interarterial anastomoses and secondary vessels from the long-finned eel Anguilla reinhardtii were examined by light and transmission electron microscopy. Interarterial anastomoses were found to originate from the primary vasculature as depressions through the tunica intima and media, from where they ran perpendicularly to the adventitial layer, before coiling extensively. From here the anastomoses travelled a relatively linear path in the outer margin of the adventitia to anastomose with a secondary vessel running in parallel with the primary counterpart. In contrast to findings from other species, secondary vessels had a structure quite similar to that of primary vessels; they were lined by endothelial cells on a continuous basement membrane, with a single layer of smooth muscle cells surrounding the vessel. Smooth muscle cells were also found in the vicinity of interarterial anastomoses in the adventitia, but these appeared more longitudinally orientated. The presence of smooth muscle cells on all aspects of the secondary circulation suggests that this vascular system is regulated in a similar manner as the primary vascular system. Because interarterial anastomoses are structurally integrated with the primary vessel from which they originate, it is anticipated that flow through secondary vessels to some extent is affected by the vascular tone of the primary vessel. Immunohistochemical studies showed that primary segmental arteries displayed moderate immunoreactivity to antibodies against 5-hydroxytryptamine and substance P, while interarterial anastomoses and secondary vessels showed dense immunoreactivity. No immunoreactivity was observed on primary or secondary arteries against neuropeptide Y or calcitonin gene-related peptide.

Branchial vascular pathways in two species of Tetraodontiformes and the concept of secondary vessels and nutrient arteries

The vascular organisation of the branchial basket was examined in two Tetraodontiform fishes; the three-barred porcupinefish, Dicotylichthys punctulatus and the banded toadfish, Marylina pleurosticta by scanning electron microscopy of vascular casts and standard histological approaches. In D. punctulatus, interarterial anastomoses (iaas) originated at high densities from the efferent filamental and branchial arteries, subsequently re-anastomosing to form progressively larger secondary vessels. Small branches of this system entered the filament body, where it was interspersed between the intrafilamental vessels. Large-bore secondary vessels ran parallel with the efferent branchial arteries, and were found to constitute an additional arterio-arterial pathway, in that these vessels exited the branchial basket in company with the mandibular, the carotid and the afferent and efferent branchial arteries, from where they gave rise to capillary beds after exit. Secondary vessels were not found to supply filament muscle; rather these tissues were supplied by single specialised vessels running in parallel between the efferent and afferent branchial arteries in both species examined. Although the branchial vascular anatomy was generally fairly similar for the two species examined, iaas were not found to originate from any branchial component in the banded toadfish, M. pleurosticta, which instead showed a moderate frequency of iaas on other vessels in the cephalic region. It is proposed that four independent vascular pathways may be present within the teleostean gill filament, the conventional arterio-arterial pathway across the respiratory lamellae; an arterio-arterial system of secondary vessels supplying the filament and non-branchial tissues; a system of vessels supplying the filament musculature; and the intrafilamental vessels (central venous sinus). The present study demonstrates that phylogenetic differences in the arrangement of the branchial vascular system occur between species of the same taxon.

Anastomotic strictures in colorectal surgery: treatment with endoscopic balloon dilation

The incidence of anastomotic stricture following colorectal surgery has increased in recent years. This complication is observed in 2-5% of all operated patients and is probably due to the greater number of low anastomoses performed with surgical staplers. We observed 31 patients with postoperative stricture, arising from one to nine months post-surgery. All patients had been treated for colorectal cancer and underwent endoscopy either during routine follow-up or for symptoms of stenosis. In 16 patients (group A) the stricture diameter was less than 4 mm and the patients had symptoms attributable to partial bowel obstruction. In the remaining 15 patients (group B), who had difficult bowel movements, the stricture diameter ranged from 4 to 8 mm. All patients were treated with endoscopic dilation using achalasia balloons. The results were considered good when the post-dilation anastomosis diameter achieved was at least 13 mm, fair when it was 9-12 mm and poor when it was less than 9 mm. The short term results (3 weeks) were good in 27 patients (87.2%), fair in 3 patients (9.6%), and poor in 1 patient (3.2%). After several unsuccessful dilations, the latter was treated by surgery. Follow-up at 3-4 months of the remaining 30 patients revealed good results in 20 (66.6%), fair in 6 (20%), and poor in 4 (13.3%). In 1 of these 4 patients, cancer recurrence was observed and a new surgical resection was performed. In 2 patients a self–expandable metal stent was inserted for 4-6 weeks, with satisfactory results. In 1 patient a biodegradable polydioxanone stent was inserted with good results after 6 months. Follow-up at 3-4 months showed good results in 25 patients. After 38 months, cancer recurrence in the area of the anastomosis was observed in 1 patient, who was treated surgically. Endoscopic dilatation should be considered the first therapeutic approach in case of anastomotic strictures, as it is immediately effective, repeatable, and does not preclude surgery if this should become necessary. .

Nuove strategie endoscopiche e mininvasive nel trattamento delle fistole anastomotiche pouch-anali e colorettali : endoluminal vacuum-assisted therapy (Endosponge®) first stage vs second stage treatment

La fistola anastomotica è una delle complicanze più temute nella chirurgia colo-rettale. Le anastomosi colo-rettali basse , le colo-anali e le pouch anali hanno un rischio più elevato di sviluppare una fistola anastomotica . La terapia endoluminale a pressione negativa (Endosponge®) è stata proposta come strategia di trattamento, tuttavia, la tempistica migliore in cui attuare la procedura rimane ancora poco definita. Lo scopo dello studio è confrontare i risultati ottenuti con l'Endosponge® come trattamento di prima linea rispetto a quelli in cui è stato applicato a seguito del fallimento di ulteriori trattamenti. Lo studio retrospettivo monocentrico ha incluso pazienti con fistola anastomotica trattati con Endosponge® in un periodo di tempo compreso tra novembre 2019 e novembre 2022. L'Endosponge® è stato applicato come prima linea o come salvataggio. Il dispositivo è stato applicato nella sede della deiscenza e periodicamente sostituito fino alla guarigione. La risoluzione del leak anastomotico è stata confermata con esame endoscopico. Dei 25 pazienti inclusi, 9 sono stati sottoposti a Endosponge® come trattamento di prima linea, mentre 16 sono stati sottoposti a Endosponge® di salvataggio. La deiscenza anastomotica è stata diagnosticata dopo un intervallo di tempo mediano di 14 giorni (range 10-413) nel primo gruppo e di 38 giorni (range 11-362) nel secondo (p=0,82). L'Endosponge® è stato applicato dopo 7 giorni (range 1-60) dalla diagnosi di fistola anastomotica nel primo gruppo e dopo 76 giorni (range 6-780) nel secondo gruppo (p=0,058). La risoluzione della fistola anastomotica è stata ottenuta in una percentuale di casi maggiore nel primo gruppo rispetto al secondo 88,9% vs 37,6% (p =0,033). Lo studio conferma l'efficacia dell'Endosponge® nel trattamento delle fistole anastomotiche colorettali basse quando utilizzato precocemente e come trattamento di prima linea.