Hypercholesterolemia-induced ocular disorder: Ameliorating role of phytotherapy

Prevalence and risk factors of diabetic retinopathy among Chinese adults with type 2 diabetes in a suburb of Shanghai, China

Background

To investigate the prevalence and risk factors of diabetic retinopathy (DR) in a Chinese population with type 2 diabetes mellitus (T2DM) in a suburb (Qingpu) of Shanghai, China.

Methods

A population-based cross-sectional study. A total of 7462 residents with T2DM in Qingpu were enrolled according to the resident health archives from January 2020 to December 2020. Blood and urine samples of the subjects were collected. Disc- and macula-centred retinal images were taken to assess DR. SPSS was used to analyse and investigate the prevalence and risk factors of DR.

Results

The fundus images of 6380 (85.5%) subjects were of sufficiently good quality for grading. The average (range) age of 6380 subjects was 63.46±7.77 (28–92) years. Six hundred forty-four subjects were diagnosed with DR. The prevalence of DR was 10.1% (95% CI 9.4%-10.8%), with mild, moderate, and severe non-proliferative retinopathy and proliferative retinopathy being 2.1%, 6.3%, 1.3% and 0.4%, respectively. The prevalence of bilateral DR was 6.5%. Higher T2DM duration (OR, 1.057), fasting plasma glucose (OR, 1.063), glycated hemoglobinA1c (OR, 1.269), urea nitrogen (OR, 1.059), and urinary albumin (OR, 1.001) were associated with the higher DR prevalence.

Conclusion

The prevalence of DR among Chinese adults with T2DM in Qingpu was 10.1%, in which non-proliferative DR was more common. Higher fasting plasma glucose and glycated hemoglobinA1c are well-known risk factors of DR, consistent with the findings in our study. Our study didn’t find the risk between lipid indicators and DR. However, several renal function indicators, like higher urea nitrogen and urinary albumin, were risk factors for DR in this study. Appropriate diagnosis and intervention should be taken in time to prevent and control DR development.

Emerging Roles of Dyslipidemia and Hyperglycemia in Diabetic Retinopathy: Molecular Mechanisms and Clinical Perspectives

Diabetic retinopathy (DR) is a significant cause of vision loss and a research subject that is constantly being explored for new mechanisms of damage and potential therapeutic options. There are many mechanisms and pathways that provide numerous options for therapeutic interventions to halt disease progression. The purpose of the present literature review is to explore both basic science research and clinical research for proposed mechanisms of damage in diabetic retinopathy to understand the role of triglyceride and cholesterol dysmetabolism in DR progression. This review delineates mechanisms of damage secondary to triglyceride and cholesterol dysmetabolism vs. mechanisms secondary to diabetes to add clarity to the pathogenesis behind each proposed mechanism. We then analyze mechanisms utilized by both triglyceride and cholesterol dysmetabolism and diabetes to elucidate the synergistic, additive, and common mechanisms of damage in diabetic retinopathy. Gathering this research adds clarity to the role dyslipidemia has in DR and an evaluation of the current peer-reviewed basic science and clinical evidence provides a basis to discern new potential therapeutic targets.

Antioxidant effect of Morus nigra on Chagas disease progression

Considering the widespread popular use of Morus nigra and the amount of scientific information on its antioxidant and anti-inflammatory activity, the effectiveness of this phytotherapeutic compound in the parasitemia progression during the acute phase of Chagas disease and its role in the development of the inflammatory process as well as its effects on the oxidative damage in the chronic phase of infection were evaluated. Thus, 96 male Swiss mice were randomly divided into eight groups, four groups were uninfected controls, and four groups were intraperitoneally infected with 5.0 x 104 blood trypomastigotes forms of T. cruzi QM2 strain. Four batches composed of one uninfected and one infected group were respectively treated with 70% alcohol solution and 25 μL, 50 μL and 75 μL of the phytotherapeutic compound. Levels of antioxidant elements (TBARS, FRAP, GSH and Sulfhydryl groups) were measured in plasma samples. The phytotherapeutic compound's antioxidant activity was measured by polyphenol and total flavonoid quantification, DPPH, NO, and FRAP method. Our results showed that the vehicle influenced some of the results that may have physiological relevance in Chagas disease. However, an important action of M. nigra tincture was observed in the progression of Chagas disease, since our results demonstrated a reduction in parasitemia of treated groups when compared to controls, especially in the group receiving 25 µL. However, in the chronic phase, the 50-µL dosage presented a better activity on some antioxidant defenses and minimized the tissue inflammatory process. Results indicated an important action of M. nigra tincture on the Chagas disease progression.

Regulation of Ca2+-Sensitive K+ Channels by Cholesterol and Bile Acids via Distinct Channel Subunits and Sites

Cholesterol (CLR) conversion into bile acids (BAs) in the liver constitutes the major pathway for CLR elimination from the body. Moreover, these steroids regulate each other's metabolism. While the roles of CLR and BAs in regulating metabolism and tissue function are well known, research of the last two decades revealed the existence of specific protein receptors for CLR or BAs in tissues with minor contribution to lipid metabolism, raising the possibility that these lipids serve as signaling molecules throughout the body. Among other lipids, CLR and BAs regulate ionic current mediated by the activity of voltage- and Ca²⁺-gated, K⁺ channels of large conductance (BK channels) and, thus, modulate cell physiology and participate in tissue pathophysiology. Initial work attributed modification of BK channel function by CLR or BAs to the capability of these steroids to directly interact with bilayer lipids and thus alter the physicochemical properties of the bilayer with eventual modification of BK channel function. Based on our own work and that of others, we now review evidence that supports direct interactions between CLR or BA and specific BK protein subunits, and the consequence of such interactions on channel activity and organ function, with a particular emphasis on arterial smooth muscle. For each steroid type, we will also briefly discuss several mechanisms that may underlie modification of channel steady-state activity. Finally, we will present novel computational data that provide a chemical basis for differential recognition of CLR vs lithocholic acid by distinct BK channel subunits and recognition sites.

Common structural features of cholesterol binding sites in crystallized soluble proteins

Cholesterol-protein interactions are essential for the architectural organization of cell membranes and for lipid metabolism. While cholesterol-sensing motifs in transmembrane proteins have been identified, little is known about cholesterol recognition by soluble proteins. We reviewed the structural characteristics of binding sites for cholesterol and cholesterol sulfate from crystallographic structures available in the Protein Data Bank. This analysis unveiled key features of cholesterol-binding sites that are present in either all or the majority of sites: i) the cholesterol molecule is generally positioned between protein domains that have an organized secondary structure; ii) the cholesterol hydroxyl/sulfo group is often partnered by Asn, Gln, and/or Tyr, while the hydrophobic part of cholesterol interacts with Leu, Ile, Val, and/or Phe; iii) cholesterol hydrogen-bonding partners are often found on α-helices, while amino acids that interact with cholesterol's hydrophobic core have a slight preference for β-strands and secondary structure-lacking protein areas; iv) the steroid's C21 and C26 constitute the "hot spots" most often seen for steroid-protein hydrophobic interactions; v) common "cold spots" are C8-C10, C13, and C17, at which contacts with the proteins were not detected. Several common features we identified for soluble protein-steroid interaction appear evolutionarily conserved.