New Grocott Stain without Using Chromic Acid

Intercellular mitochondrial transfer as a means of revitalizing injured glomerular endothelial cells

BACKGROUND

Recent studies have demonstrated that mesenchymal stem cells (MSCs) can rescue injured target cells via mitochondrial transfer. However, it has not been fully understood how bone marrow-derived MSCs repair glomeruli in diabetic kidney disease (DKD).

AIM

To explore the mitochondrial transfer involved in the rescue of injured glomerular endothelial cells (GECs) by MSCs, both in vitro and in vivo.

METHODS

In vitro experiments were performed to investigate the effect of co-culture with MSCs on high glucose-induced GECs. The transfer of mitochondria was visualized using fluorescent microscopy. GECs were freshly sorted and ultimately tested for apoptosis, viability, mRNA expression by real-time reverse transcriptase-polymerase chain reaction, protein expression by western blot, and mitochondrial function. Moreover, streptozotocin-induced DKD rats were infused with MSCs, and renal function and oxidative stress were detected with an automatic biochemical analyzer and related-detection kits after 2 wk. Kidney histology was analyzed by hematoxylin and eosin, periodic acid-Schiff, and immunohistochemical staining.

RESULTS

Fluorescence imaging confirmed that MSCs transferred mitochondria to injured GECs when co-cultured in vitro. We found that the apoptosis, proliferation, and mitochondrial function of injured GECs were improved following co-culture. Additionally, MSCs decreased pro-inflammatory cytokines [interleukin (IL)-6, IL-1β, and tumor necrosis factor-α] and pro-apoptotic factors (caspase 3 and Bax). Mitochondrial transfer also enhanced the expression of superoxide dismutase 2, B cell lymphoma-2, glutathione peroxidase (GPx) 3, and mitofusin 2 and inhibited reactive oxygen species (ROS) and dynamin-related protein 1 expression. Furthermore, MSCs significantly ameliorated functional parameters (blood urea nitrogen and serum creatinine) and decreased the production of malondialdehyde, advanced glycation end products, and ROS, whereas they increased the levels of GPx and superoxide dismutase in vivo. In addition, significant reductions in the glomerular basement membrane and renal interstitial fibrosis were observed following MSC treatment.

CONCLUSION

MSCs can rejuvenate damaged GECs via mitochondrial transfer. Additionally, the improvement of renal function and pathological changes in DKD by MSCs may be related to the mechanism of mitochondrial transfer.

Grocott Methenamine Silver Staining Is the Optimal Approach to Histological Diagnosis of Pulmonary Cryptococcosis

Background

Histological staining methods for Cryptococcus identification vary in accuracy. This study aimed to investigate the clinical value of Grocott methenamine silver (GMS), periodic acid-Schiff (PAS), and Alcian blue (AB) staining in the diagnosis of pulmonary cryptococcosis (PC).

Methods

From April 2004 to June 2021, the clinical and pathological data of 152 patients with PC were collected from the Department of Pathology, Sun Yat-sen University Cancer Center. The sensitivity and identifiability of GMS, PAS, and AB staining for histological diagnosis were systematically evaluated using statistical methods combined with the microscopic characteristics of PC cases.

Results

Statistical analysis showed that the detection rates of GMS, PAS, and AB staining were 100.0% (152/152), 94.7% (144/152), and 81.6% (124/152), respectively. McNemar’s test showed that the sensitivity of GMS was significantly higher than those of PAS (P = 0.008) and AB stains (P < 0.001). Both PAS and AB stains had obvious non-specific staining, which interfered with the detection of Cryptococcus, and increased diagnostic difficulties. In contrast, in GMS staining, Cryptococcus spores were prominent with a clean background and were clearly observed at low or medium power magnification, with the identifiability significantly better than those of PAS or AB staining.

Conclusion

GMS staining had sensitivity up to 100%, and identifiability that was better than those of PAS and AB staining. GMS is the best method for histological diagnosis of PC.

New Insights into the Pathogenesis of Diabetic Nephropathy: Proximal Renal Tubules Are Primary Target of Oxidative Stress in Diabetic Kidney

Diabetic nephropathy is a major source of end-stage renal failure, affecting about one-third cases of diabetes mellitus. It has long been accepted that diabetic nephropathy is mainly characterized by glomerular defects, while clinical observations have implied that renal tubular damage is closely linked to kidney dysfunction at the early stages of diabetic nephropathy. In this study, we conducted pathohistological analyses focusing on renal tubular lesions in the early-stage diabetic kidney with the use of a streptozotocin (STZ)-induced diabetes mellitus mouse model. The results revealed that histological alterations in renal tubules, shown by a vacuolar nucleic structure, accumulations of PAS-positive substance, and accelerated restoration stress, occur initially without the presence of glomerular lesions in the early-stage diabetic kidney, and that these tubular defects are localized mainly in proximal renal tubules. Moreover, enhanced expression of RAGE, suggesting an aberrant activation of AGEs-RAGE signaling pathway, and accumulation of oxidative modified mitochondria through the impaired autophagy/lysosome system, were also seen in the damaged diabetic proximal renal tubules. Our findings indicate that proximal tubular defects are the initial pathological events increasingly linked to the progression of diabetic nephropathy, and that controlling renal tubular damage could be an effective therapeutic strategy for the clinical treatment of diabetic nephropathy.

Majocchi's granuloma: current perspectives

Majocchi’s granuloma (MG) is a rare fungal infection of the dermis that is mainly caused by dermatophytes (in ≥95% of cases); the most frequently identified cause is anthropophilic Trichophyton rubrum. In the rest of the cases, the causes are non-dermatophytic fungi such as Aspergillus species. This review aimed to provide information about the current perspectives on MG regarding its clinical characteristics, predisposing factors, laboratory diagnosis, and treatment strategies. Although the lower extremities were reported to be the most common site of infection, facial involvement has been predominant in the past 5 years. Our literature research showed that the most common predisposing factor (55%) is the use of topical steroid creams without potassium hydroxide examination during treatment of erythematous squamous dermatoses. A reliable diagnosis of MG is based on histopathological examination, including fungal culture and molecular analyses. MG should be treated not only with topical agents but also with systemic antifungal agents that are continued until the lesions are completely resolved. In systemic treatment, the most preferred drug is terbinafine, because of its efficacy, side effects, and safety.

Electron Microscopic Study Using Formalin-fixed, Paraffin-embedded Material, with Special Reference to Observation of Microbial Organisms and Endocrine Granules

In the diagnostic pathology practice, specimens for electron microscopy (EM) are not necessarily handled and fixed under the ideal condition. In the present article, the author describes ultrastructural study using formalin-fixed and/or paraffin-embedded material. The fine morphologic preservation is often acceptable, particularly when small cubes are dug out of paraffin blocks. Particulate structures such as neuroendocrine granules and microbes are consistently observed even using paraffin sections. Paraffin sections signalized with silver particles in Grimelius and Grocott stains or diaminobenzidine products in immunostaining and in situ hybridization are applicable to EM evaluation by using a pre-embedding sequence. The practical merit includes the targeted approach: highly accurate sampling from focal lesions can be achieved for EM analysis, after observing hematoxylin and eosin-stained or specific-signalized paraffin-sections. This allows us pathologists a convenient and practical way for identifying focally infected pathogens, as well as a retrospective ultrastructural analysis of rare lesions long kept as a form of paraffin blocks.