Systematic Study of the Multiple Variables Involved in V2AlC Acid-Based Etching Processes, a Key Step in MXene Synthesis.

The realization of the broad range of application of MXenes relies on the successful and reproducible synthesis of quality materials of tailored properties. To date, most MXenes have been produced making use of acid-based etching methods, yet an in-depth understanding of etching processes is lacking. Herein, we have engaged in a comprehensive study of the multiple variables involved in the synthesis of V2CTx with focus on the properties of etched materials. Two main sets of experiments were considered, each using a different V2AlC precursor and a range of synthesis variables including reaction time and temperature, mixing rate, and type of acid. Correlations of synthesis conditions-materials properties were investigated using a broad range of characterization techniques including analytical methods, scanning and transmission electron microscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Findings indicated the crucial relevance of properties of the MAX precursor such as elemental composition, particle size, and crystal structure on etching processes and properties of etched materials. Particularly, depending on the MAX precursor, two etching patterns were identified, core-shell and plate-by-plate, the latter describing a more efficient etching. Combined studies of elemental composition, crystal structure, and yield quantification allowed us to evaluate the effectiveness of etching processes. XRD studies revealed key crystal-structure-type of acid correlations showing advantages of using a HF/HCl mix over only HF. Analytical methods XRD and XPS delivered insights into undergoing chemical processes and their influence on bulk and surface chemistry of etched materials. The relevance for reaction kinetics of highly correlated variables such as reaction vessel dimensions, mixing efficiency, and reaction temperature was recognized. For the first time, a MXene synthesis has been investigated comprehensively highlighting its multivariable nature and the high variable intercorrelation, opening up venues for further investigation on MAX and MXene synthesis.

[Increased vascular density with indirect myocardial revascularization in normal rat hearts]. / Mayor densidad vascular con revascularización miocárdica indirecta en corazones normales de ratas

BACKGROUND: The aim of this study was to identify if the interaction of myocardial revascularization methods increases the functional vascular area. METHODS: A 4x3 factorial design was performed in 11 groups, five rats per group, ten samples per rat, evaluated at 45 days postoperative, with different surgical combinations. The magnitude of the interaction was evaluated by immunoexpression of vascular endothelium-derived growth factor, fibroblast growth factor and tyrosine receptor, to allow the activity of vascular endothelium-derived growth factor, fibroblast growth factor and thrombin (Flk-1), as well as vascular area measurement; Both measures were performed by computerized morphometry. RESULTS: An increase in immunohistochemical expression and vascular area in direct proportion to the interaction was identified; It can be affirmed (ANOVA p < 0.0001), that with the interaction of all the maneuvers the maximum effect is achieved. CONCLUSIONS: It is demonstrated that indirect myocardial revascularization has a specific weight within the integral myocardial revascularization with a real impact on cost-benefit and cost-effectiveness.

Introducción: el objetivo de este trabajo fue identificar si la interacción de los métodos de revascularización miocárdica incrementa el área vascular funcional. Métodos: se realizó un estudio con un diseño factorial de 4x3 en 11 grupos, de cinco ratas por grupo, diez muestras por rata, evaluado a 45 días del posoperatorio, con las diferentes combinaciones quirúrgicas. La magnitud de la interacción fue evaluada tanto por inmunoexpresión del factor vascular de crecimiento derivado del endotelio, factor de crecimiento de fibroblastos y receptor de tirosina, para permitir la actividad del factor vascular de crecimiento derivado del endotelio, factor de crecimiento de fibroblastos y trombina (Flk-1), así como de la medición del área vascular; ambas medidas fueron realizadas por morfometría computarizada. Resultados: se identificó un incremento de la expresión inmunohistoquímica y del área vascular en proporción directa con la interacción; se puede afirmar (ANOVA p < 0.0001), que con la interacción de todas las maniobras se logra el efecto máximo. Conclusiones: se demuestra que la revascularización miocárdica indirecta tiene un peso especifico dentro de la revascularización miocárdica integral con un impacto real en el costo-beneficio y el costo-efectividad.

O-GlcNAc-selective-N-acetyl-beta-D-glucosaminidase activity and mRNA expression in muscle is related to glucosamine-induced insulin resistance.

Glucosamine (GlcN)-induced insulin resistance is associated with an increase in O-linked-N-acetylglucosaminylated modified proteins (O-GlcNAcylated proteins). The role played by O-GlcNAc-selective-N-acetyl-beta-D-glucosaminidase (O-GlcNAcase), which removes O-N-acetyl-glucosamine residues from O-GlcNAcylated proteins, has not yet been demonstrated. We investigated whether GlcN-induced whole-body insulin resistance is related to tissue O-GlcNAcase activity and mRNA expression. GlcN (30 mumol/kg/min) or physiological saline (control) was intravenously infused into Sprague-Dawley rats for 2 h. After GlcN treatment, rats were subjected to the following: intravenous glucose tolerance test, insulin tolerance test or removal of the liver, muscle and pancreas. GlcN was found to provoke hyperglycemia compared to control (8.6 +/- 0.41 vs. 4.82 +/- 0.17 mM, p < 0.001). The insulin resistance index (HOMA-IR) increased (15.76 +/- 1.47 vs. 10.14 +/- 1.41, p < 0.001) and the beta-cell function index (HOMA-beta) diminished (182.69 +/- 22.37 vs. 592.01 +/- 103, p < 0.001). Liver glucose concentration was higher in the GlcN group than in the control group (0.37 +/- 0.04 vs. 0.24 +/- 0.038 mmol/g dry weight, p < 0.001). Insulin release index (insulin/glucose) was less in the GlcN group than in the control (2.2 +/- 0.1 vs. 8 +/- 0.8 at 120 min, p < 0.001). In the GlcN group, muscle O-GlcNAcase activity diminished (0.28 +/- 0.019 vs. 0.36 +/- 0.018 nmol of p-nitrophenyl/mg protein/min, p < 0.001), and K(m) increased (1.51 +/- 0.11 vs. 1.12 +/- 0.1 mM, p < 0.001) compared to the control. In the GlcN group, O-GlcNAcase activity/mRNA expression was altered (0.6 +/- 0.07 vs. 1 +/- 0.09 of control, p < 0.05). In conclusion, O-GlcNAcase activity is posttranslationally inhibited during GlcN-induced insulin resistance.

Influence of platelet-rich plasma on bone regeneration: a histomorphometric study in rabbit calvaria.

PURPOSE: The aim of this study was to evaluate whether local application of platelet-rich plasma (PRP) would induce bone regeneration in cranial defects on rabbits. MATERIALS AND METHODS: Twelve female New Zealand rabbits were used for this study. Two identical 10-mm-diameter bicortical cranial defects were created in each animal. One of the defects was grafted with PRP, while the contralateral was left unfilled as a negative control. Animals were sacrificed at 2, 4, 6, and 8 weeks after surgery, and biopsy specimens were evaluated histologically and histomorphometrically under light microscopy. Analysis of variance was used for statistical analysis. RESULTS: The histomorphometric evaluation showed more regenerated bone after local administration of PRP at 2 weeks (P > .05), 4 weeks (P < .05), and 6 weeks (P > .05). At week 8, new bone formation was comparable in both groups. CONCLUSION: In this animal model, local application of PRP in bone defects enhances healing significantly at 4 weeks.

Effect of parathyroidectomy on cardiac fibrosis and apoptosis: possible role of aldosterone.

BACKGROUND/AIM: It has been demonstrated that parathyroidectomy prevents left ventricular hypertrophy in uremic animals. Although this effect may be mediated by direct actions of parathormone (PTH), it may also be exerted through regulation of profibrotic factors such as aldosterone. In adrenal cortex cell cultures, PTH increases aldosterone release. The objective of this work is to assess the effect of parathyroidectomy on aldosterone levels and on cardiac fibrosis and apoptosis in uremic rats. METHODS: Four groups of rats were studied: C, control; 5/6Nx, 5/6 nephrectomy; PTx, parathyroidectomy, and 5/6NxPTx, 5/6 nephrectomy plus parathyroidectomy. Thirty days after the last surgical procedure the animals were sacrificed. Serum creatinine, ionized calcium, aldosterone, PTH, cardiac weight, fibrosis and apoptosis were measured. RESULTS: Serum creatinine levels were significantly higher in 5/6Nx and 5/6NxPTx groups (1.62 +/- 0.21 and 1.38 +/- 0.15 mg/dl) than in C and PTx groups (0.66 +/- 0.02 and 0.47 +/- 0.01 mg/dl, p < 0.001). Potassium levels were significantly higher in the 5/6Nx and 5/6NxPTx groups (5.2 +/- 0.3 and 5.4 +/- 0.3 mg/dl) than in the C group (4.3 +/- 0.06 mg/dl, p < 0.05). Values in 5/6Nx and 5/6NxPTx groups were not significantly different from each other. PTH levels were significantly higher in the 5/6Nx group (470.5 +/- 156.3 microg/ml) than in the controls (102.3 +/- 14.3 microg/ml). PTH levels in the PTx group (1.78 +/- 0.52 microg/ml) and in the 5/6NxPTx group (81.64 +/- 32.15 microg/ml) were similar to control values. Ionized calcium was lower in PTx and 5/6NxPTx groups (0.80 +/- 0.07 and 0.89 +/- 0.07 mmol/l) as compared with C and 5/6Nx groups (1.14 +/- 0.01 and 0.96 +/- 0.01 mmol/ l, p < 0.01). The heart weight as percentage of the body weight increased significantly in 5/6Nx animals (4.20 +/- 0.15%) compared to the C group (3.41 +/- 0.27%, p < 0.05); parathyroidectomy reversed the heart weight increment in the 5/6NxPTx animals (3.58 +/- 0.16%). Myocardial fibrosis was significantly higher in the 5/6Nx group (12.5 +/- 1.1%) than in the C group (7.3 +/- 1.5%, p < 0.001); in the 5/6NxPTx animals fibrosis returned towards control values (8.9 +/- 0.2%). Myocardial apoptosis rose significantly in 5/6Nx animals (24.3 +/- 1.2%) compared to the C group (6.7 +/- 0.83%, p < 0.001); parathyroidectomy reversed the apoptosis in the 5/6NxPTx animals (10.4 +/- 0.49%). Aldosterone levels increased significantly in the 5/6Nx group (2,461 +/- 257 pg/ml) compared to the C group (703 +/- 81 pg/ml, p < 0.001); in the 5/6NxPTx animals aldosterone levels were below control values (509 +/- 99 pg/ml). CONCLUSIONS: Uremia was associated to myocardial hypertrophy, fibrosis and apoptosis. Surgically induced hypoparathyroidism prevented the development of these disorders. Our results suggest that in the remnant kidney rat model myocardial hypertrophy, fibrosis, and apoptosis are mediated by high circulating aldosterone levels. Aldosterone, in turn, may be regulated by PTH.

[Ovarian denervation and polycystic ovary]. / Denervación y poliquistosis ováricas.

BACKGROUND: Ovarian inervation is limited to the superior pedicle and ovarian artery to loose itself within the gonadal smooth muscle. Hence, it is far from clear how is it that the ovary preserves its communication with hypothalamic and pituitary structures for feedback regulation. There is a lack of precision concerning structures and mechanisms involved in the genesis of polycystic disease. OBJECTIVE: To know the role of inervation associated to hormone stimuli in developing polycystic ovaries. MATERIAL AND METHODS: Groups of Sprague Dawley rats were studied: group 1, whom received cornoil (vehicle) served as controls; group 2 had estradiol valerianate (EV) and group 3 was exposed to phenol for denervation and also received estradiol valerianate (EV). After sacrifice, ovaries were exposed and saved in a formol solution until preparation and staining with hematoxilin-eosin and for immunochemical reaction using specific monoclonal antibodies for nerve tissue (PS-100 & GFAP). RESULTS: Biologic response was considered when follicle dilation was seen under microscopy evaluation. The ovaries with higher follicle development belonged to group 2 (EV) while preserving intrinsic follicular nervous activity as shown by a positive immunoreaction to PS-100 & GFAP. Those denervated and exposed to EV (group 3) did not show significant changes in follicular size resembling controls. CONCLUSIONS: The presence of neural activity is vital for development of cysts and the neural mechanisms involved seemed to lie within the ovarian cells.

Presence of a failed kidney transplant in patients who are on hemodialysis is associated with chronic inflammatory state and erythropoietin resistance.

Patients returning to hemodialysis (HD) after failure of their kidney transplant suffer from high morbidity and mortality rates. It is common practice to keep failed kidney transplants in place. It is not known if these failed kidney transplants induce an inflammatory state that contributes to morbidity and mortality. In a single facility, patients starting on HD with failed kidney transplant were identified (Group A) and screened for the presence of chronic inflammatory state. Those with clinical symptoms attributed to the failed allograft (Group A1) were not offered transplant nephrectomy unless deemed necessary during follow-up. Their clinical and laboratory data were followed up for 6 months. Similar data were obtained from a group of incident HD patients (Group B). Forty-three patients had a failed Kidney transplant (Group A). Of these, 29 comprised Group A1 and 14 Group A2. Group B comprised 121 patients. In comparison with Group B, Group A exhibited worse anemia and erythropoietin resistance index (ERI), had lower serum albumin and prealbumin, and higher CRP. Group A1 had lower Hb and higher ferritin, CRP, and ESR in comparison with Group A2. Following transplant nephrectomy, Group A1 had improvement in ERI, serum albumin, prealbumin, ferritin, fibrinogen, CRP, and ESR. At 6 months, Group A1 had higher Hb and serum albumin levels, and lower CRP and ERI in comparison with Group A2. Group B parameters showed no change during follow-up. Patients returning to HD following failure of their kidney transplant suffer from a chronic inflammatory state. Resection of failed transplants in symptomatic patients is associated with amelioration of markers of chronic inflammation. Transplant nephrectomy should be considered a treatment option for patients with failed kidney transplants, especially if they exhibit signs and symptoms of chronic inflammatory state.