Video-Assisted Anal Fistula Treatment for Treatment of Complex Cryptoglandular Anal Fistulas with 2 Years Follow-Up Period: Our Experience.

Aim: The aim of this prospective, nonrandomized, observational study was to present our results in operative treatment of complex anal fistulas using video-assisted anal fistula treatment (VAAFT) procedure with a curative intent in 2 years follow-up period. Materials and Methods: Between March 2016 and March 2018, 73 patients underwent the VAAFT procedure. Postoperative follow-up was 2 years, up to March 2020. Only patients with complex cryptoglandular anal fistulas were included. All patients were referred for magnetic resonance imaging of the pelvis. Fecal incontinence severity index score was used to assess any continence disturbance prior operation and postoperatively. Result: Primary healing occurred in 52 cases (71.23%) after first operation. From 21 patients who had recurrence or who had persisting disease, 16 patients accepted reoperation with second VAAFT procedure and additionally 10 patients achieved healing. From a total number of 73 patients who were included in study healing ultimately occurred in 62 cases (84.93%). In the first operation internal opening was identified in 47 cases (64.38%) and was closed with mattress suture, rectal advancement flap or ligation of intersphincteric fistula tract technique depending on its extent and type of fistula. Median primary healing rate was 6 weeks. There were no serious intra- or postoperative complications. None of the patients reported any type of continence disturbance. Discussion: VAAFT has been shown to offer good rates of healing, low morbidities, possibilities of multiple attempts in case of first failure and this series adds to the literature.

The proposed mechanism of action during different pain management techniques on expression of cytolytic molecule perforin in patients after colorectal cancer surgery.

The postoperative period is accompanied with neuroendocrine, metabolic and immune alteration which is caused by tissue damage, anesthesia, postoperative pain and psychological stress. Postoperative pain contributes to dysfunction of immune response as a result of interaction between central nervous and immune system. The postoperatively activated hypotalamo-pituitary-adrenocortical axis, sympathic and parasympathic nerve systems are important modulators of immune response. According to bidirectional communication of immune and nervous system, appropriate postoperative pain management could affect immune response in postoperative period. Although the postoperative suppression of immune response has been reported, a very little are known about the influences of different pain management techniques on cytotoxic function of immune cells in patients with colorectal cancer in early postoperative period. Perforin is a cytotoxic molecule expressed by activated lymphocytes which has a crucial role in elimination of tumor cells and virus-infected cells, mostly during the effector's phase of immune response. Immune compromise during the postoperative period could affect the healing processes, incidence of postoperative infections and rate and size of tumor metastases disseminated during operation. The pharmacological management of postoperative pain in patients with malignancies uses very different analgesic techniques whose possible influence on cytotoxic functions of immune cells are still understood poor. For decades the most common way of treating postoperative pain after colorectal cancer surgery was intravenous analgesia with opiods. In the last decade many investigations pointed out that opiods can also contribute to postoperative suppression of immune response. Epidural analgesia is a regional anesthesia technique that acts directly on the origin of pain impulses and pain relief can be achieved with small doses of opiods combined with local anesthetics. Local anesthetics potentate analgesic properties of opiods but per se are also acting as antiinflammatory drugs. Afferent neural blockade by epidural analgesia attenuates neuroendocrine stress response. We propose that epidural analgesia could be more convenient that intravenous analgesia in maintenance of immunological homeostasis that is altered by surgical stress, tumor growth and pain.

The renal Na+/phosphate cotransporter NaPi-IIa is internalized via the receptor-mediated endocytic route in response to parathyroid hormone.

The major renal Na(+)/phosphate cotransporter, NaPi-IIa, is regulated by a number of factors including parathyroid hormone (PTH), dopamine, and dietary phosphate intake. PTH induces the acute internalization of NaPi-IIa from the brush border membrane (BBM) and its routing to and subsequent degradation in lysosomes. Previous work indicated that megalin, part of the apical receptor-mediated endocytic apparatus, may play a role in the PTH-induced removal of NaPi-IIa. Here we examined in rats the time-dependent internalization route of NaPi-IIa after acute PTH application using immunohistochemistry and markers of several endocytic compartments. NaPi-IIa removal from the BBM was detectable as early as 5 min after PTH injection. After 10-15 min, NaPi-IIa was localized in subapical compartments positive for clathrin. Shortly thereafter, NaPi-IIa appeared in endosomes stained for EEA1 (early endosomal antigen 1). After 45-60 min, NaPi-IIa was found in late endosomes/lysosomes marked with lgp120. In contrast, no change in the subcellular localization of megalin and the Na(+)/H(+) exchanger NHE3 was detected up to 60 min after PTH injection. To further characterize the internalization route, insulin, as a marker for receptor-mediated endocytosis, and horseradish peroxidase (HRP) and fluorescein isothiocyanate (FITC)-dextran (10 kDa), as markers for fluid-phase mediated endocytosis, were used. NaPi-IIa colocalized with insulin 5-30 min after PTH injection but did not overlap with HRP or FITC-dextran. These results demonstrate a distinct internalization route of NaPi-IIa in response to acute PTH application that may involve the receptor-mediated endocytic pathway including clathrin-coated vesicles and EEA1-positive early endosomes, and routes NaPi-IIa to lysosomes for degradation.

Segment-specific expression of sodium-phosphate cotransporters NaPi-IIa and -IIc and interacting proteins in mouse renal proximal tubules.

Sodium-dependent phosphate cotransport in renal proximal tubules (PTs) is heterogeneous with respect to proximal tubular segmentation (S1 vs. S3) and nephron generation (superficial vs. juxtamedullary). In the present study, S1 and S3 segments of superficial and juxtamedullary nephrons were laser-microdissected and mRNA and protein expression of the Na/Pi-cotransporters NaPi-IIa and NaPi-IIc and the PDZ proteins NHERF-1 and PDZK1 determined. Expression of NaPi-IIa mRNA decreased axially in juxtamedullary nephrons. There was no effect of dietary Pi content on NaPi-lla mRNA expression in any proximal tubular segment. The abundance of the NaPi-IIa cotransporter in the brush-border membrane showed inter- and intranephron heterogeneity and increased in response to a low-Pi diet (5 days), suggesting that up-regulation of NaPi-lla occurs via post-transcriptional mechanisms. In contrast, NaPi-IIc mRNA and protein was up-regulated by the low-Pi diet in all nephron generations analysed. NHERF-1 and PDZK1, at both mRNA and protein levels, were distributed evenly along the PTs and did not change after a low-Pi diet.

Regulation of the renal type IIa Na/Pi cotransporter by cGMP.

Inhibition of proximal tubular phosphate (Pi) reabsorption involves, as far as we know, brush border membrane retrieval of the type IIa Na/Pi-cotransporter. The aim of the present study was to analyze whether intracellular cGMP-mediated regulation of Pi reabsorption also involves retrieval of the type IIa Na/Pi-cotransporter, as previously shown for cAMP. Atrial natriuretic peptide (ANP) and nitric oxide (NO) were used to stimulate guanylate cyclase. In vivo perfusion of mice kidneys with either ANP or NO donors resulted in a downregulation of type IIa Na/Pi-cotransporters on the brush border membranes of proximal tubules. These effects were mimicked by activation of protein kinase G with 8Br-cGMP. In in-vitro-perfused mice proximal tubules, ANP was effective when added either to the apical or basolateral perfusate, suggesting the presence of receptors on both membrane sites. The effects of ANP and NO were blocked by the protein kinase G inhibitor LY 83553. Parallel experiments in OK cells, a renal proximal tubule model, provided similar information. Our findings document that cGMP-mediated regulation (ANP and NO) of type IIa Na/Pi-cotransporters also takes place via internalization of the transporter protein.

Interaction of the type IIa Na/Pi cotransporter with PDZ proteins.

The type IIa Na(+)-dependent inorganic phosphate (Na/P(i)) cotransporter is localized in the apical membrane of proximal tubular cells and is regulated by an endocytotic pathway. Because molecular processes such as apical sorting, internalization, or subsequent degradation might be assisted by associated proteins, a yeast two-hybrid screen against the C-terminal, cytosolic tail of type IIa cotransporter was designed. Most of the potential proteins found belonged to proteins with multiple PDZ modules and were either identical/related to PDZK1 or identical to NHERF-1. Yeast trap truncation assays confined the peptide-protein association to the C-terminal amino acid residues TRL of type IIa cotransporter and to single PDZ domains of each identified protein, respectively. The specificity of these interactions were confirmed in yeast by testing other apical localized transmembraneous proteins. Moreover, the type IIa protein was recovered in vitro by glutathione S-transferase-fused PDZ proteins from isolated renal brush border membranes or from type IIa-expressing oocytes. Further, these PDZ proteins are immunohistochemically detected either in the microvilli or in the subapical compartment of proximal tubular cells. Our results suggest that the type IIa Na/P(i) cotransporter interacts with various PDZ proteins that might be responsible for the apical sorting, parathyroid hormone controlled endocytosis or the lysosomal sorting of internalized type IIa cotransporter.