Electronic transitions and vibrational properties of bulk and monolayer g-C3N4, and a g-C3N4/MoS2 heterostructure from a DFT study.

Successful recognition of a dynamically stable carbonitride structure revealed that unlike other planar layered structures in the case of g-C3N4 the stable configurations are distorted [J. Wang et al., Chem. Mater., 2017, 29(7), 2694-2707, DOI: https://doi.org/10.1021/acs.chemmater.6b02969.]. This generates interest in a detailed study of the possibilities of controlling the structure and its properties both in its pristine and heterostructure forms. Here, we present the results of the investigation of dynamically stable bulk and monolayer g-C3N4, and a g-C3N4/MoS2 heterostructure. The bulk g-C3N4 was found to be an indirect band gap semiconductor exhibiting an indirect-to-direct band gap transition upon dimensionality reduction. In the case of the heterostructure, the analysis of partial density of states shows a charge transfer from nitrogen ions in g-C3N4 to the MoS2 layer. The Raman spectra of bulk g-C3N4 are discussed in detail, and the changes occurring in the spectra upon the transition to the monolayer form and in the g-C3N4/MoS2 heterostructure are demonstrated. It was found that the characteristic features of such an atomic transition can be seen in the region below 300 cm-1 and between 700 and 800 cm-1.

Phonon dynamics in MoSi2N4: insights from DFT calculations.

We have reported the density functional theory investigations on the monolayered, 2 layered and bulk MoSi2N4 in three structural modifications called α1 [Y.-L. Hong, et al., Chemical Vapor Deposition of Layered Two-Dimensional MoSi2N4 Materials, Science, 2020, 369(6504), 670-674, DOI: 10.1126/science.abb7023], α2 and α3 [Y. Yin, Q. Gong, M. Yi and W. Guo, Emerging Versatile Two-Dimensional MoSi2N4 Family, Adv. Funct. Mater., 2023, 2214050, DOI: 10.1002/adfm.202214050]. We showed that in the case of monolayers the difference in total energies is less than 0.1 eV between α1 and α3 phases, and less than 0.2 eV between α1 and α2 geometries. The most energetically favorable layer stacking for the bulk structures of each phase was investigated. All considered modifications are dynamically stable from a single layer to a bulk structure in energetically favorable stacking. Raman spectra for the monolayered, 2 layered and bulk structures were simulated and the vibrational analysis was performed. The main difference in the obtained spectra is associated with the position of the strongest band which depends on the Mo-N bond length. According to the obtained data, we can conclude that the Raman line at 348 cm-1 in the experimental spectra of MoSi2N4 can have more complex explanation than just Γ-point Raman-active vibration as was discussed before in [Y.-L. Hong, et al., Chemical Vapor Deposition of Layered Two-Dimensional MoSi2N4 Materials, Science, 2020, 369(6504), 670-674, DOI: 10.1126/science.abb7023].

The electronic structure and spin states of 2D graphene/VX2 (X = S, Se) heterostructures.

The structural, magnetic and electronic properties of 2D VX2 (X = S, Se) monolayers and graphene/VX2 heterostructures were studied using a DFT+U approach. It was found that the stability of the 1T phases of VX2 monolayers is linked to strong electron correlation effects. The study of vertical junctions comprising of graphene and VX2 monolayers demonstrated that interlayer interactions lead to the formation of strong spin polarization of both graphene and VX2 fragments while preserving the linear dispersion of graphene-originated bands. It was found that the insertion of Mo atoms between the layers leads to n-doping of graphene with a selective transformation of graphene bands keeping the spin-down Dirac cone intact.

Nonstoichiometric Phases of Two-Dimensional Transition-Metal Dichalcogenides: From Chalcogen Vacancies to Pure Metal Membranes.

Two-dimensional (2D) membranes consisting of a single layer of Mo atoms were recently manufactured [ Adv. Mater. 2018 , 30 , 1707281 ] from MoSe2 sheets by sputtering Se atoms using an electron beam in a transmission electron microscope. This is an unexpected result as formation of Mo clusters should energetically be more favorable. To get microscopic insights into the energetics of realistic Mo membranes and nonstoichiometric phases of transition-metal dichalcogenides (TMDs) MaXb, where M = Mo and W and X = S, Se, and Te, we carry out first-principles calculations and demonstrate that the membranes, which can be referred to as metallic quantum dots embedded into a semiconducting matrix, can be stabilized by charge transfer. We also show that an ideal neutral 2D Mo or W sheet is not flat but a corrugated structure, with a square lattice being the lowest-energy configuration. We further demonstrate that several intermediate nonstoichiometric phases of TMDs are possible as they have lower formation energies than pure metal membranes. Among them, the orthorhombic metallic 2D M4X4 phase is particularly stable. Finally, we study the properties of this phase in detail and discuss how it can be manufactured by the top-down approaches.

Lower urinary tract reconstruction following a cystectomy: experience and results in 20 patients using the "Studer" orthotopic ileal bladder substitution.

INTRODUCTION AND OBJECTIVE: To analyze the outcome, complications and functional results in patients undergoing bladder substitution with the Studer continent urinary pouch. MATERIALS AND METHODS: At our Clinic, between January 2005 and December 2006, 20 male patients underwent a radical cystoprostatectomy followed by the Studer orthotopic bladder substitution. RESULTS: The transitional cell carcinoma was found to be the most frequent histopathological type. The distribution by grade and pathological stage showed all were high grade infiltrating tumors localized in the bladder. We observed 3 patients with neobladder-unrelated complications: one patient with a wound infection and 2 patients with a prolonged ileus. CONCLUSION: In conclusion, our results with urinary diversion are promising in patients recquiring a radical cystoprostatectomy. We believe that the Studer's orthotopic neobladder is an excellent alternative for patients suffering a radical cystectomy and offers a sufficient protection of the upper urinary tract with a low complication rate, good voiding function and continence (Tab. 1, Ref. 25). Full Text (Free, PDF) www.bmj.sk.

Do we have to treat subclinical rejections in early protocol renal allograft biopsies?

The aim of the present study was to evaluate whether treatment of subclinical, borderline rejections (SR/BR) or histological findings of chronic allograft nephropathy (CAN) in protocol biopsies in the first month posttransplantation after living related kidney transplantation has a beneficial effect on graft histology and renal function at 6 months. Among the 40 paired biopsies, only 6/80 showed no histological lesions. BR was found in 13/40 and 12/40, and SR in 15/40 and 21/40 of patients on the 1- and 6-month biopsies, respectively. The mean histological index/total sum of scores for acute and chronic changes (HI) increased at 6-month biopsy: 5.3 +/- 2.9 vs 7.8 +/- 3.6 (P < .001). Similarly, the mean sum of histological markers for chronicity (CAN score) of 2.1 +/- 1.5 increased to 4.6 +/- 2.3 (P < .001) on the 6-month biopsy. When divided according to whether there was treatment of BR and SR, the treated BR/SR group on 1-month biopsy had a mean HI score of 7.11 +/- 1.9, which remained almost the same (7.11 +/- 2.32) at 6 months. Among the untreated BR/SR group it increased from 4.95 +/- 1.99 to 8.16 +/- 4.30. However, there was no difference in graft function between the groups from 1 to 6 months. In conclusion, a protocol 1-month biopsy may be valuable to establish the prevalence of BR/SR in stable allografts. The presence of an untreated BR/SR upon a 1-month biopsy showed greater susceptibility for histological deterioration on the 6-month biopsy due to an accelerated CAN process.

De novo malignancies after renal transplantation--a single-center experience in the Balkans.

The occurrence of malignancies is a well-known serious complication after organ transplantation. Despite the fact that many factors may be involved, the pathogenesis is still unclear. The aim of the present study was to examine the incidence and clinical characteristics of de novo malignancies that arise after renal transplantation over a 13-year experience in a single center in the Balkan Peninsula. During this period, 185 renal transplantations (139 living related and 46 cadaveric) were followed in our department. Overall, 19 malignancies (9.78%) were observed in 15 patients (7.8%). The mean age of these patients was 45 years (range, 21-53 years). Ten patients (55%) developed skin cancers: 8 squamous and 2 basal cell. Kaposi's sarcomas were found in 3 patients (16.6%, 1 visceral form). We also detected 1 breast cancer, 1 seminoma, 1 colon cancer, 1 urogenital-transitional cell-like cancer, 1 renal cell carcinoma, 1 plasmacytoma, and 1 retroperitoneal sarcoma after an ABO incompatible transplantation. All cancers were de novo malignancies that presented at a mean time of 21 months (range, 2-52 months) after surgery. In conclusion, the incidence of malignancy in the present series was similar to that reported elsewhere. The predominance of skin cancers was understandable bearing in mind the sunshine. The appearance of skin malignancies in our group of patients was earlier, more severe, and multiple sites. No cases of posttransplantation lymphoproliferative disorders were observed. Careful clinical examination and long-term screening protocols are needed for early detection and treatment of this life-threatening complication among the transplant population.

Relationship between E-cadherin and fibroblast growth factor receptor 2b expression in bladder carcinomas.

E-cadherin is a cell-cell adhesion molecule expressed predominantly by epithelial cells. Reduction or loss of E-cadherin immunoreactivity has been associated with tumour progression in many epithelial cancers, including bladder carcinomas. The fibroblast growth factor receptor 2b (FGFR2b) recognized specifically by FGF7 is expressed only by epithelial cells. Recently, decreased expression of FGFR2b protein and mRNA was found to be associated with tumour progression in bladder carcinomas. The purpose of this investigation was to look for a possible relationship between E-cadherin and FGFR2b expression in bladder carcinomas. As decreased E-cadherin immunoreactivity was found to correlate directly with decreased expression at the mRNA level, the possible relationship between E-cadherin and FGFR2b was investigated at the mRNA level using semi-quantitative RT - PCR in 92 transitional cell carcinomas (TCCs) and four lymph node metastases. All tumours with low E-cadherin expression had low expression of FGFR2b, whereas tumours with low FGFR2b mRNA could express any level of E-cadherin mRNA. The same observation was equally valid for bladder and colon cancer cell lines suggesting that, besides bladder tumours, this relationship could apply to other carcinomas types. These results suggest that a relationship exists between the transcription of the E-cadherin and FGFR2b genes preventing high expression of FGFR2b where expression of E-cadherin is low. We suggest that reduced expression of FGFR2b in conjunction with decreased expression of E-cadherin may contribute to the aggressive behaviour attributable to high grade TCCs.

Living-unrelated (paid) renal transplantation--ten years later.

Due to the increase of organ shortage and still inadequate development of cadaver transplantation, many end-stage patients from the Balkan region travel mostly to India to buy a kidney. Despite all the ethical dilemmas and discussions, organ sales is present nowdays in Third-World countries. Sixteen patients (13 from Macedonia and 3 from Kosovo, SCG) were observed clinically during a period of 10 years. Recipients of mean age 36.5 years (range 10 to 58) displayed the following underlying diseases: chronic glomerulonephritis (n = 5), urethral valves with reflux (n = 2), ADPKD (n = 1), hypertensive nephropathy (n = 4), lithiasis (n = 1), and unknown cause of ESRD (n = 3). The donor population was young (22 to 29 years). Most patient records did not include data on HLA, cross-match, MLC, kind of surgery, or usual pretransplant workup. The immunosuppressive protocol included CyA, PRED, and AZA or MMF. All transplanted patients were followed on an outpatient basis in our department; patients with complications were hospitalized. The 1, 3, 5, and 10 year Kaplan Meier graft survival rates were 78.6%, 50.2%, 33.3%, and 18.8%, respectively. Seven patients were lost (43.7%), two during the first month after transplantation, two at the end of the first year, and three at 5, 6, and 8 years thereafter. The main reasons for death were severe pulmonary infections with sepsis, hepatitis B with liver cirrhosis, Kala Azar, CMV, and cancer of the colon. Five grafts were lost due to repeated rejection episodes and chronic graft nephropathy. The last three cases remained with good renal function and actual serum creatinine values of 135 +/- 9. In view of this experience, the authors cannot recommend this type of transplantation, not only from the ethical point of view, but also from frequent medical and surgical complications which are sometimes life threatening.

Protocol biopsies in kidney transplant recipients: histologic findings as prognostic markers for graft function and outcome.

The aim of the present study was to identify subclinical and borderline rejections as well as histological markers of chronic allograft nephropathy (CAN) among protocol biopsies performed at 1 and 6 months after living related kidney transplantation to assess their possible implications for graft function. Twenty paired allograft biopsies performed at 1 and 6 months were reviewed according to the Banff scoring scheme. The mean ages of donors and recipients were 59.6 +/- 13.8 and 34.4 +/- 8.7 years, respectively. Among all biopsies only 10% (4/40) showed no histopathological lesions. At the first month borderline rejection was shown in 35% and subclinical rejection in 10% of patients. At 6 months the proportion of findings was even higher, namely, 40% and 30%, respectively. When divided according to donor age, donors above 55 years showed a mean CAN score of 2.33 +/- 1.56 which increased to 5.0 +/- 2.26 on the 6 month biopsy (214.3%). Unexpectedly, the proportion of these changes in the younger donor group also increased by 173.3%, which might have been explained by the greater number of borderline and subclinical rejections in the younger donor group at the 1 month biopsy. In conclusion, 1 month biopsy may be valuable to determine borderline and subclinical rejection and to prognosticate the outcome of renal allograft function. Our findings suggest a greater susceptibility of histological deterioration among the older donor population. However, the presence of an untreated rejection in the younger donor pool leads to a rapid impairment of the graft function accelerating the process of chronic allograft nephropathy.

Alterations of microsatellite loci GSN and D18S51 in urinary bladder cancer.

BACKGROUND: Transitional cell carcinoma (TCC) of urinary bladder cancer is the most common malignancy in the urinary system. Genetic instability is an essential property of malignant neoplasms and could be evaluated by microsatellite analysis. Alterations in numerous microsatellite loci are already described in urinary bladder TCC. The aim of this study was to investigate the usefulness of only two microsatellite loci for the detection of bladder TCC, and their correlation with the major clinicopathological parameters. METHODS: We analyzed the tissue samples derived from 70 patients with histopathologically confirmed TCC of the urinary bladder, collected by transurethral resection, and samples of normal bladder mucosa derived from 40 patients with nonmalignant diseases. Microsatellite alleles GSN and D18S51 were amplified in paired samples of tissue and leukocyte DNA from each patient, and were analyzed by electrophoresis. RESULTS: Microsatellite alterations at either GSN or D18S51locus, or in both, were detected in 46 out of the 70 patients (65.71 %) with TCC, but not in the patients of the control group. We found a significant statistical correlation between the frequencies of patients with microsatellite alterations in the examined loci and all three grades of histopathological T-classification. No significant correlation was found regarding the stages or the occurrence of recidivism, metastasis or cancer-related death within the two-year follow-up period. CONCLUSIONS: This study indicates that two selected microsatellite markers could have a potential value in clinical and pathological evaluation of urinary bladder TCC, especially regarding the prediction of tumor differentiation. Additional studies and further validation of the method are needed. Hippokratia 2015; 19 (3): 200-204.

Living related renal transplantation--the use of advanced age donors.

AIM: Efforts to increase the donor pool and available organs included some unconventional kidney transplantation. One of these was including elderly donors for both, living and cadaver kidney transplantation. The aim of the study was to review our single centre experience with living donor transplants from elderly advanced age donors. PATIENTS AND METHODS: During a period of 7 years, 71 living related renal transplantations were performed. Twenty-six of them were over 65 (mean 69+/-4, range 65 to 81), but 10 were over 70 years of age. The survival rate was compared with 45 transplants from younger donors (mean age 51+/-6, range 24 to 59). The cold and warm ischemia time, the preservation procedure and blood vessels anastomosis time were comparable in both donor groups. The immunosuppression included sequental quadruple protocol with ATG, PRED, AZA and CyA replacing ATG after 7 days. The triple drug (AZA, PRED, CyA) maintenance therapy was applied to all recipients. RESULTS: Kaplan-Meier 1-, 3- and 5-year graft survival was 88.0%, 79.2% and 68%, respectively, for advanced donor age group and 90.2%, 82.4% and 74%, respectively, for younger donor group. The difference was slightly statistically significant (p < 0.05). In 6 patients who received graft from elderly donors, a delayed graft function was observed, whereas only in one in the younger donor group. CONCLUSION: Despite the worse results in the elderly donors' transplants, we consider the advanced age donors as an important source of kidneys contributing to solving the actual organ shortage, especially in our region.

Living emotionally related renal transplantation (LERT)--single center experience in the Balkans.

BACKGROUND: As elsewhere, the growing organ shortage is a main problem for organ transplantation. To solve the problem, we started accepting genetically unrelated, but emotionally related living donors. METHODS: In the period of 1998-2002, 14 LERT are performed in the University Clinical Centre in Skopje, Republic of Macedonia. As suitable donors are used predominantly spouses, but also mother and brother in law. The immunosuppression included a quadruple protocol with Interleukin-2R antagonists, late cyclosporin A, MMF and steroids. The two-year graft and patients survival of LERT was compared with 22 living genetically related donor transplantation (LRT) performed in the same time. RESULTS: The two years graft survival was 100% in LERT and 92% in LRT. There are not any significant difference among the medical and surgical complications between the two groups of pts. The actual serum creatinin was 101+22 in LERT compared with 142+34 in LRT. CONCLUSION: The authors recommend the LERT as a valid alternative especially in the countries where the regular cadaver transplantation is not yet established.

[Kidney transplantation in Macedonia]. / Transplantation rénale en Macédoine.

During the last 10 years we performed 92 renal transplantations in our Skopje hospital (Macedonia), using 22 cadaver donors and 70 living donors. We also performed 15 explanations from cadavers and seven kidneys were allocated to former Yugoslavia. Standard surgical procedures were used for both living and cadaver donor explantations and transplantations. For living explantations, donors were matching in 66 cases (94.28%) and in four cases (5.7%) non-matching donors who however were relatives of the patient Explantations and transplantations took place only after all ethical- and legal-related problems had been solved. The minimum acceptable HLA mismatch was 50% with negative present or historical cross-match. A quadruple sequential immunosuppressive treatment was used, including either poly- or monoclonal globulins (thymoglobulin [ATG], lymphoglobulin [ALG], daclizumab, OKT-3) as an induction therapy and prednisolone, azathriopin and cyclosporin A as maintenance therapy. Rejection episodes were treated by pulse MP therapy or OKT-3 and increased doses of MMF if the patients were steroid-resistant. Kaplan-Meier survival curves showed that survival at 12, 36 and 60 month reached 90%, 75% and 60%, respectively. Survival was better after transplantation using a graft from a living donor than after transplantation using a graft from a cadaver donor (survival rates: 92%, 82% and 68% at 12, 36 and 60 months after surgery). Delayed graft functioning (DGF) was observed in 16 patients (17.3%), reaching 46.6% after transplantation of a graft from a cadaver donor and 10% after transplantation of a graft from a living donor. The relatively high percentage of DGF in the living donor program was due to the use of grafts from elderly donors (over 65 years of age). We registered 26 (29%) episodes of acute rejection that were predominantly histologically confirmed and further classified according to the BANFF criteria. Treatment of five steroid-resistant rejections proved to be successful. Neither early nor late surgical and medical complications were different from those reported in the literature. Despite the modest number of kidney transplantations, chronic renal failure has decreased in our region. The authors expect further improvement in this powerful therapeutic procedure thanks to links with regional and European transplant centers allowing better cooperation and organ sharing.

[Use of the vena cava in renal transplantation. Extension of the right renal vein]. / Utilisation de la veine cave en transplantation rénale. Le prolongement de la veine rénale droite.

Vena cava is a providential material for the transplant surgeon. Prolongation of the right renal vein using vena cava is a simple and effective procedure. Consequently the inferior vena cava must be harvested with the right and not the left kidney for which it is unnecessary. The use of a long segment of vena cava makes the renal transplantation and easy, well-defined procedure without interfering with the requirements of multiorgan donation.

[Results of the treatment of bladder tumors infiltrating the muscle]. / Résultats du traitement des tumeurs vésicales infiltrant le muscle.

Recent studies have shown improvements in survival in patients with invasive bladder cancer, perhaps as a result of stage selection and reduced perioperative morbidity rather than of increased effectiveness of treatments. The main ongoing therapeutic trials (combined use of chemotherapy with either surgery or radiation therapy) aim at controlling occult metastases which may be present in up to 50% of apparently localized bladder cancers. Identification of risk factors for metastatic disease is therefore crucial. In this study, factors potentially associated with response to treatment were analyzed on the basis of a review of outcomes reported with current treatments.

[The use of monoclonal antibodies in the evaluation of the aggressiveness of tumors of the bladder]. / Apport des anticorps monoclonaux dans l'évaluation de l'agressivité des tumeurs de vessie.

Monoclonal antibodies produced using hybridoma technology have enabled identification of new tumor markers. Targets include tumor-associated antigens, growth factors and their receptors, blood group antigens, cell proliferation antigens, oncogene or tumor suppressor gene products, and markers for drug resistance. Immunohistochemical or flow cytometry studies performed with monoclonal antibodies can be used to determine the immunophenotype of normal and tumoral urothelium; specificity may be primarily for superficial or deep tumors, or for different tumor grades. A number of monoclonal antibodies have been found of prognostic value independently from conventional prognostic criteria. Others have shown diagnostic value. The most promising monoclonal antibodies are reviewed herein.

[Epidemiology of the major histocompatibility complex-human leukocyte antigen in the Madeconian population]. / Epidémiologie du complexe majeur d'histocompatibilité "human leucocyte antigens" dans la population macédonienne.

Human leukocyte antigens (HLA) at loci A (14 antigens) and loci B (29 antigens) were determined in 2,385 healthy Macedonians, using the microlymphocytotoxicity test. Results were compared with those obtained in Caucasians. The most common HLA antigens in the Macedonian population are: A2 (51.65%), A1 (25.87%), A3 (17.14%) and A24 (20.41%) for loci A and B51 (32.03%), B35 (23.98%), B8 (12.11%), B44 (12.11%), B7 (11.48%) and B18 (10.23%) for loci B. These frequencies are similar to those found in Caucasians. However, antigens B12, B44, B7, B8 and especially B15 are more common in Caucasians, while B51 and B35 antigens are more common in the Macedonian population. The most common haplotypes in the Macedonian population are: A2/B51 (15.68%), A2/B35 (10.35%), A2/B12 (7.79%), A9/B51 (7.50%) and A1/B8 (7.50%). The frequencies of HLA antigens were also determined in 348 patients with chronic renal disease and compared with those observed in the healthy population (2,385 subjects). No significant differences was observed between HLA frequencies depicted in patients and those described in healthy individuals. Results should therefore make easier the finding of compatible kidney transplants in the Macedonian population.

[Nephrectomy in a living donor by retroperitoneal laparoscopy or lomboscopy]. / Prélèvement rénal chez le donneur vivant par voie laparoscopique rétropéritonéale ou lomboscopie.

INTRODUCTION: The advantages of laparoscopic live donor nephrectomy are now well documented. This new approach can lower donor morbidity and could stimulate living related organ donation. We described our original operative technique and report our preliminary results. MATERIAL AND METHODS: Since 1998, we have used the retroperitoneal laparoscopy in tree related living donors. Advantages and inconvenient of this new surgical procedure were discussed with each donors and inform consent obtained. The left kidney was harvested in the three cases. RESULTS: The operative time was inferior to 280 minutes, warm ischemia less than five minutes and bleeding less than 150 mL. Patients were discharged between the 2nd and 3rd post-operative days. CONCLUSION: Retroperitoneal laparoscopy is a valuable alternative in transplant centres with skilled laparoscopic surgeons.

[Living donors: immunologic factors]. / Donneurs vivants: aspects immunologiques.

Transplantations using grafts from living donors were performed on 70 patients with chronic kidney failure, 66 of them involved matching recipients-donors and four involved non-matching recipients-donors. Immunological data were analyzed in 56 pairs of recipients and patients. Of these pairs, one was identical, seven had three identical antigens, 46 were haploidentical at A and B loci, one pair was identical in one antigen and one pair was completely incompatible. The survival of transplanted kidneys largely depended on the degree of histocompatibility. In 33 (59%) transplantations kidneys are functioning from more than 36 months. In the group of seven transplanted pairs with three identical antigens kidneys are functioning in six cases, with four of them functioning from more than 72 months. In the remaining patients (41 patients [73%]) kidneys are functioning, with 8 of them functioning from more than 10 years. The existence of HLA antibodies was investigated. Preimmunization was found in 18 (32%) patients and correlated with the number of blood transfusions. Rejection crises were observed in 12 (21%) patients. As the number of blood transfusions per patient increased the number of rejection crises decreased. Rejection crises were also observed in haploidentical pairs, with a relative risk > 30%. They occurred in the first 2 weeks following transplantation.