Macro-AST as a cause of hypertransaminasemia: an uncommon entity but it exists

Macroenzymes are complexes formed by the binding of enzyme molecules to each other or to other plasma components. We report the clinical case of a woman with abnormal liver enzymes secondary to macro-AST. Macro-AST should be considered in the differential diagnosis as a cause of isolated AST elevation, thus avoiding unnecessary additional tests.

Metformin and Glucose Concentration as Limiting Factors in Retinal Pigment Epithelial Cell Viability and Proliferation

Metformin is a well-established drug for the treatment of type 2 diabetes; however, the mechanism of action has not been well described and many aspects of how it truly acts are still unknown. Moreover, regarding in vitro experiments, the glycaemic status when metformin is used is generally not considered, which, added to the suprapharmacological drug concentrations that are commonly employed in research, has resulted in gaps of its mechanism of action. The aim of this study was to determine how glucose and metformin concentrations influence cell culture. Considering that diabetic retinopathy is one of the most common complications of diabetes, a retinal pigment epithelial cell line was selected, and cell viability and proliferation rates were measured at different glucose and metformin concentrations. As expected, glucose concentration by itself positively influenced cell proliferation rates. When the metformin was considered, results were conditioned, as well, by metformin concentration. This conditioning resulted in cell death when high concentrations of metformin were used under physiological concentrations of glucose, while this did not happen when clinically relevant concentrations of metformin were used independently of glucose status. Our study shows the importance of in vitro cell growth conditions when drug effects such as metformin's are being analysed.

Phosphorus May Induce Phenotypic Transdifferentiation of Vascular Smooth Muscle Cells through the Reduction of microRNA-145

Phosphorus is a vital element for life found in most foods as a natural component, but it is also one of the most used preservatives added during food processing. High serum phosphorus contributes to develop vascular calcification in chronic kidney disease; however, it is not clear its effect in a population without kidney damage. The objective of this in vivo and in vitro study was to investigate the effect of high phosphorus exposure on the aortic and serum levels of miR-145 and its effect on vascular smooth muscle cell (VSMCs) changes towards less contractile phenotypes. The study was performed in aortas and serum from rats fed standard and high-phosphorus diets, and in VSMCs exposed to different concentrations of phosphorus. In addition, miR-145 silencing and overexpression experiments were carried out. In vivo results showed that in rats with normal renal function fed a high P diet, a significant increase in serum phosphorus was observed which was associated to a significant decrease in the aortic α-actin expression which paralleled the decrease in aortic and serum miR-145 levels, with no changes in the osteogenic markers. In vitro results using VSMCs corroborated the in vivo findings. High phosphorus first reduced miR-145, and afterwards α-actin expression. The miR-145 overexpression significantly increased α-actin expression and partially prevented the increase in calcium content. These results suggest that miR-145 could be an early biomarker of vascular calcification, which could give information about the initiation of the transdifferentiation process in VSMCs.

EBUS-guided transbronchial mediastinal cryobiopsy in the diagnosis of mediastinal lesions: safety, feasibility and diagnostic yield – experience in 50 cases

Background

Endobronchial ultrasound guided transbronchial needle aspiration (EBUS-TBNA) is the technique of choice in the study of mediastinal and hilar lesions; however, it can be affected by the insufficiency of intact biopsy samples, which might decrease its diagnostic yield for certain conditions, thus requiring re-biopsies or additional diagnostic procedures such as mediastinoscopy when probability of malignancy remains high.

Objectives

Our objectives were to 1) attempt to reproduce this technique in the same conditions that we performed EBUS-TBNA, that is, in the bronchoscopy suite and under moderate sedation; 2) describe the method used for its execution; 3) determine its feasibility by accessing different lymph node stations applying our method; 4) analyze the diagnostic yield and its complications.

Methods

Prospective study of 50 patients who underwent EBUS-TBNA and EBUS-guided TMC in a single procedure using a 22-G TBNA needle and a 1.1 mm cryo-probe subsequently between January and August 2022. Patients with mediastinal lesions greater than 1 cm were recruited and EBUS-TBNA and TMC were performed in the same lymph node station.

Results

The diagnostic yield was 82% and 96% for TBNA and transbronchial mediastinal cryobiopsy, respectively. Diagnostic yields were similar for sarcoidosis, while cryobiopsy was more sensitive than TBNA in lymphomas and metastatic lymph nodes. As for complications, there was no pneumothorax and in no case was there significant bleeding. There were no complications during the procedure or in the follow-up of these patients.

Conclusions

TMC following our method is a minimally invasive, rapid, and safe technique that can be performed in a bronchoscopy suite under moderate sedation, with a higher diagnostic yield than EBUS-TBNA, especially in cases of lymphoproliferative disorders and mestastatic lymph nodes, or when more biopsy sample is needed for molecular determinations.

Comparison of biotransformation of inorganic selenium by Lactobacillus and Saccharomyces in lactic fermentation process of yogurt and kefir

The aim of the present study was to characterize, quantify, and compare the different selenium species that are produced when lactic fermentation with two different types of microorganisms, bacteria (Lactobacillus) and yeast (Saccharomyces), take place to produce yogurt and kefir, respectively, and to study the transformation process of these species as a function of time. These two dairy products were chosen for the study because they are highly consumed in different cultures. Moreover, the microorganisms present in the fermentation processes are different. While the bacteria Lactobacillus is the one responsible for yogurt fermentation, a partnership between bacteria and the yeast Saccharomyces causes kefir fermentation. A comparative study has been carried out by fermenting Se(IV) enriched milk in the presence of both types of microorganisms, where the concentration range studied was from 0.5 to 20 microg g (-1). Enzymatic extraction enabled selenium speciation profiles, obtained by anionic exchange and ion-pairing reversed phase high performance liquid chromatography (IP-RP-HPLC) with inductively coupled plasma mass spectrometry (ICP-MS) detection. Scanning electron microscopy (SEM) applied to the enriched samples showed segregated Se (0), at added concentrations higher than 5 microg g (-1). The main Se species formed depended on the type of microorganism involved in the fermentation process, SeCys 2 and MeSeCys being the main species generated in yogurt and SeMet in kefir. The results obtained are different for both kinds of samples. Lactic fermentation for yogurt produced an increment in selenocystine (SeCys 2) and Se-methylselenocysteine (MeSeCys), while fermentation to produce kefir also incremented the selenomethionine (SeMet) concentration. The Se species are stable for at least 10 and 15 days for kefir and yogurt, respectively. After this period, selenocystine concentration decreased, and the concentration of Se-methylselenocysteine was found to significantly increase.

[Microhematuria secondary to mucocele and appendicular cystoadenoma]

Appendiceal mucocele is a rare entity consisting of cystic dilatation of the appendix as a result of increased mucus production. Most cases are related to the presence of a cystadenoma. This appendiceal neoplasm is frequently associated with other extraintestinal and colonic tumors and therefore adequate abdominal examination is necessary. The clinical presentation is nonspecific and varies from asymptomatic forms to abdominal discomfort and, less frequently, to urological manifestations. We describe the case of a woman with hematuria associated with an appendiceal mucocele. Only a few cases have been reported in the medical literature. The treatment of choice of cystadenoma is surgery and simple mucocele cannot be macroscopically differentiated from cystadenoma and cystadenocarcinoma. Survival in patients with appendiceal cystadenoma is excellent. The 5-year survival rate is reduced by at least half in patients with cystadenocarcinoma associated with pseudomyxoma peritonei.