Tyramine and vanadate synergistically stimulate glucose transport in rat adipocytes by amine oxidase-dependent generation of hydrogen peroxide

Nonadrenergic imidazoline I2-binding sites colocalize with monoamine oxidase (MAO) in various tissues. As white adipocytes from various species have been reported to be very rich in I2-sites, the authors consider whether these cells show a substantial MAO activity and explore its functional role. Oxidation of [14C]tyramine by rat adipocyte membranes was dependent on both MAO and semicarbazide-sensitive amine oxidase (SSAO). Tyramine oxidation was identical in membranes and in intact adipocytes (Vmax: 11-12 nmol/min/mg protein). A similar effect of MAO and SSAO inhibitors was obtained in both the intact cells and the membranes: half of the activity was sensitive to semicarbazide and the other half more easily inhibited by MAO-A than by MAO-B inhibitors. As the reaction catalyzed by amine oxidases generates H2O2, which mimicks certain insulin effects in adipocytes, we tested whether tyramine oxidation influences glucose transport in adipocytes. One mM tyramine weakly stimulated glucose transport. A clear potentiation of tyramine effect occurred in the presence of 0.1 mM vanadate, ineffective by itself, reaching half-maximal insulin stimulation. This stimulation was sensitive to MAO and SSAO inhibitors and to catalase. The 5-fold activation of glucose transport was accompanied by translocation of GLUT4 transporters to the plasma membrane. This shows that tyramine is readily oxidized by adipocytes and potentiates the effects of vanadium on glucose transport through release of hydrogen peroxide. The role of the amine oxidases, which are highly expressed in adipocytes, allows them to be considered as more than mere scavengers of circulating amines.

Contribution of initial lymphatics to oral wound healing after tooth extraction

Lymphatics are involved in the resolution of inflammation and wound healing, but their role in the oral wound healing process after tooth extraction has never been investigated. We therefore sought to evaluate the healing process following the extraction of maxillary molars in two transgenic mouse models: K14-VEGFR3-Ig mice, which lack initial mucosal lymphatic vessels, and K14-VEGFC mice, which have hyperplastic mucosal lymphatics. Maxillary molars were extracted from both transgenic mouse types and their corresponding wild-type (WT) controls. Mucosal and alveolar bone healing were evaluated. A delayed epithelialization and bone regeneration were observed in K14-VEGFR3-Ig mice compared with their WT littermates. The hampered wound closure was accompanied by decreased levels of epidermal growth factor (EGF) and persistent inflammation, characterized by infiltrates of immune cells and elevated levels of pro-inflammatory markers in the wounds. Hyperplastic mucosal lymphatics did not enhance the healing process after tooth extraction in K14-VEGFC mice. The findings indicate that initial mucosal lymphatics play a major role in the initial phase of the oral wound healing process.

Interdisciplinary combined sacrocolporectopexy: Results after one-year follow-up

Objective

Multicompartmental pelvic floor descensus typically affects women after menopause, leading to a combination of faecal and urinary incontinence, dyspareunia, and evacuation disorders. The aim of this study was to access postoperative quality of life and complications as well as outcome after one-year follow-up after operation of multicompartmental pelvic floor prolapse (POP).

Methods

All Patients undergoing ventral mesh rectopexy by surgical department and anterior mesh sacrocolpopexy by gynecologists at the same time between 2015 and 2020 were enrolled. The study is a retrospective cohort study approved by the local Ethics committee. Follow-up was scheduled at 6 weeks, 6, and 12 months and consisted of clinical examination and questionnaires. Perioperative and long-time morbidity was assessed according to the Clavien-Dindo classification. Quality of life and patients’ satisfaction were evaluated at each consultation.

Results

Twenty-seven patients were included. All patients were seen at one-year follow-up.

Demographic and clinical features are reported in Table 1. Preoperatively, 22 patients (81.5%) were diagnosed with stage II-III (POP-Q) prolapse and severe multicompartment descensus detected on Magnetic Resonance (MR). Laparoscopic surgery was performed in 92.5% of cases and intraoperative conversion was necessary in 2 cases. In 15 cases (55%) a Dynamesh® Visible, in 11 cases (41%) a Gynamesh®, and in one (4%) case a Surgipro™ Mesh was used. No severe complications (Clavien-Dindo >=3) occurred postoperatively. 90-day mortality was 0%. Intraoperatively, a total of 1 vaginal, and 2 bladder lesions were corrected and healed without consequences. At 1 year, patients reported a high level of satisfaction and massive improvement of QoL (8.5 Pt. VAS Scale). During follow-up, one patient had to be reoperated because of incisional hernia and one to cover vaginal mesh exposure. A tension free vaginal tape (TVT) had to be inserted in 4 patients (15%) due to new onset of urinary incontinence. Symptomatic recurrence of prolapse did not occur.

Conclusion

Interdisciplinary combined sacrocolporectopexy is an effective therapy of multicompartmental pelvic floor descensus. It is a safe procedure with low perioperative morbidity and high patients’ satisfaction. Therefore, it might be the procedure of choice to correct multicompartmental POP.

O-099 The use of cumulus cells (CCs) to select spermatozoa for intracytoplasmic sperm injection improves blastocyst development and quality

Study question

Is there a role for sperm selection based on the capacity to pass through cumulus oophorous column in improving the laboratory outcomes in ICSI cycles?

Summary answer

A higher rate of blastocyst formation and quality are obtained with the use of CCs to select spermatozoa for ICSI compared to conventional density gradients.

What is known already

The sperm selection for ICSI is an operator-dependent procedure based on sperm morphology and motility. ICSI bypasses all natural barriers of sperm selection, which may impact embryo development.

During natural fertilization, only the spermatozoa that pass-through cumulus cells will have the chance to fertilize the egg. Spermatozoa capable of traverse COCs have better morphology, higher chromatin integrity and greater acrosomal reaction. Hyaluronic acid is an important component of these cells and plays a key role in the selection of spermatozoa with intact DNA. However, there is scarce data regarding this selection method for ICSI on the development of the embryo.

Study design, size, duration

This is a prospective randomized sibling oocyte pilot study (February-December 2021). A total of 996 metaphase II (MII) oocytes were randomized into two groups. In the control group (Group 0, n = 489 MII), ICSI was performed with sperm selected by conventional density gradients. In the study group (Group 1, n = 507 MII) the oocytes were microinjected with sperm selected through CCs. The main outcome was blastocyst formation rate and quality. Reproductive results were analyzed as secondary outcomes.

Participants/materials, setting, methods

Ninety-eight couples undergoing ICSI (private center) with ≥6 fresh own MII obtained after ovarian stimulation, embryo culture until blastocyst stage and ejaculated sperm samples were included in the study.

All seminal samples were processed using density gradients and those in the study group were additionally passed through CCs (the patient's own CCs were used in all cases).

Fertilization and day 5 blastocyst formation rates were assessed. Embryo quality was scored according to Gardner's criteria.

Main results and the role of chance

Data was similar with regards to cause of infertility, maternal age (36.47 vs 36.63 y.o.), sperm count (60.53 vs 58.25 mill/ml) and progressive motility (57.45 vs 57.50%) between group 0 vs 1, respectively.

Fertilization rate was similar between groups (74.0% vs 78.7%; p = 0.419. Group 0 vs 1, respectively). However, the blastocyst formation rate was significantly higher in the study group compared to control (70.9% vs 60.1%; p = 0.002). In addition, high-quality blastocyst rate was significantly higher in the CCs compared to the control group (49.6% vs 38.5%; p = 0.003). After the analysis of 145 treatments (131 frozen vs 14 fresh transfers) the cumulative clinical pregnancy rate in the study group was 47.2%, higher than in the control group (32.1%), but without reaching statistical difference (p = 0.07).

Limitations, reasons for caution

This is an exploratory study, aimed to evaluate the effectiveness of CCs as a more “physiologic” selection of spermatozoa for ICSI treatments in terms of laboratory outcomes (blastocyst formation rate and quality). Albeit not reaching statistical significance, the higher cumulative pregnancy rate in the study group seems clinically relevant.

Wider implications of the findings

Our results suggest that CCs can select more competent sperm for ICSI. This “physiologic-resembling”, operator-independent selection method has the potential of increasing pregnancy outcomes in ICSI cycles, pending of confirmation in larger studies including cumulative embryo-transfer cycles.

Trial registration number

NA

Semicarbazide-sensitive amine oxidase substrates stimulate glucose transport and inhibit lipolysis in human adipocytes

Semicarbazide-sensitive amine oxidases (SSAO) are widely distributed enzymes scavenging biogenic or exogenous amines and generating hydrogen peroxide. We asked whether human adipose tissue could express SSAO. Since hydrogen peroxide exhibits pharmacological insulin-like effects, we also tested whether its endogenous production by SSAO could mimic several insulin effects on adipocytes, such as stimulation of glucose uptake and inhibition of lipolysis. The benzylamine oxidation by human adipose tissue was inhibited by semicarbazide or hydralazine and resistant to pargyline or selegiline. It was due to an SSAO activity localized in adipocyte membranes. A protein of 100-kDa and a 4-kb mRNA corresponding to SSAO were identified in either mammary or abdominal subcutaneous fat depots. In isolated adipocytes, SSAO oxidized similarly benzylamine and methylamine that dose dependently stimulated glucose transport in a semicarbazide-sensitive manner. Antioxidants also inhibited the benzylamine and methylamine effects. Moreover, the ability of diverse substrates to be oxidized by adipocytes was correlated to their effect on glucose transport. Benzylamine and methylamine exerted antilipolytic effects with a maximum attained at 1 mM. These results show that human adipocytes express a membrane-bound SSAO that not only readily oxidizes exogenous amines and generates H(2)O(2), but that also interplays with glucose and lipid metabolism by exerting insulin-like actions. Based on these results and the fact that variations in plasma levels of the soluble form of SSAO have been previously reported in diabetes, we propose that determination of adipocyte SSAO, feasible on subcutaneous microbiopsies, could bring relevant information in pathologies such as obesity or diabetes.

Substrates of semicarbazide-sensitive amine oxidase co-operate with vanadate to stimulate tyrosine phosphorylation of insulin-receptor-substrate proteins, phosphoinositide 3-kinase activity and GLUT4 translocation in adipose cells

It has been shown that the combination of benzylamine or tyramine and low concentrations of vanadate markedly stimulates glucose transport in rat adipocytes by a mechanism that requires semicarbazide-sensitive amine oxidase (SSAO) activity and H(2)O(2) formation. Here we have further analysed the insulin-like effects of the combination of SSAO substrates and vanadate and we have studied the signal-transduction pathway activated in rat adipocytes. We found that several SSAO substrates (benzylamine, tyramine, methylamine, n-decylamine, histamine, tryptamine or beta-phenylethylamine), in combination with low concentrations of vanadate, stimulate glucose transport in isolated rat adipocytes. Furthermore, SSAO substrates together with vanadate stimulated the recruitment of GLUT4 to the cell surface in isolated rat adipocytes. Benzylamine plus vanadate also stimulated glucose transport and GLUT4 translocation in 3T3-L1 adipocytes. Benzylamine or tyramine in combination with vanadate potently stimulated the tyrosine phosphorylation of both insulin receptor substrate (IRS)-1 and IRS-3. In contrast, benzylamine and vanadate caused only a weak stimulation of insulin receptor kinase. Benzylamine or tyramine in combination with vanadate also stimulated phosphoinositide 3-kinase activity; wortmannin abolished the stimulatory effect of benzylamine and vanadate on glucose transport in adipose cells. Furthermore, the administration of benzylamine and vanadate in vivo caused a rapid lowering of plasma glucose levels, which took place in the absence of alterations in plasma insulin. On the basis of these results we propose that SSAO activity regulates glucose transport in adipocytes. SSAO oxidative activity stimulates glucose transport via the translocation of GLUT4 carriers to the cell surface, resulting from a potent tyrosine phosphorylation of IRS-1 and IRS-3 and phosphoinositide 3-kinase activation. Our results also indicate that substrates of SSAO might regulate glucose disposal in vivo.

[Malignant rhabdoid tumor of the kidney in the adult]

Presentation of a malignant rhabdoid renal tumour. This type of sarcoma which occurs commonly during the paediatric age is exceptional in the adult, this being the reason for reviewing this clinical case and its management. The term rhabdoid includes several types of morphologically similar tumours which make analysis and pathological categorization difficult. A description of the classification criteria and likely origin of the tumour is included.