Elucidating the Relationship Between Diabetes Mellitus and Parkinson's Disease Using 18F-FP-(+)-DTBZ, a Positron-Emission Tomography Probe for Vesicular Monoamine Transporter 2

Recent progress in the applications of presynaptic dopaminergic positron emission tomography imaging in parkinsonism

Nowadays, presynaptic dopaminergic positron emission tomography, which assesses deficiencies in dopamine synthesis, storage, and transport, is widely utilized for early diagnosis and differential diagnosis of parkinsonism. This review provides a comprehensive summary of the latest developments in the application of presynaptic dopaminergic positron emission tomography imaging in disorders that manifest parkinsonism. We conducted a thorough literature search using reputable databases such as PubMed and Web of Science. Selection criteria involved identifying peer-reviewed articles published within the last 5 years, with emphasis on their relevance to clinical applications. The findings from these studies highlight that presynaptic dopaminergic positron emission tomography has demonstrated potential not only in diagnosing and differentiating various Parkinsonian conditions but also in assessing disease severity and predicting prognosis. Moreover, when employed in conjunction with other imaging modalities and advanced analytical methods, presynaptic dopaminergic positron emission tomography has been validated as a reliable in vivo biomarker. This validation extends to screening and exploring potential neuropathological mechanisms associated with dopaminergic depletion. In summary, the insights gained from interpreting these studies are crucial for enhancing the effectiveness of preclinical investigations and clinical trials, ultimately advancing toward the goals of neuroregeneration in parkinsonian disorders.

Application of hyperbaric oxygen therapy in diabetic foot ulcers: A meta-analysis

Hyperbaric oxygen therapy (HBOT) has been used in patients with diabetic foot ulcers (DFU) for many years, but its clinical efficacy is still controversial. Therefore, this study explored the efficacy of HBOT applied to DFU by means of meta-analysis. PubMed, Cochrane Library, Embase, CNKI and Wanfang databases were searched, from database inception to October 2023, and published randomised controlled trials (RCTs) of HBOT in DFU were collected. Two investigators independently screened the collected literature, extracted relevant data and assessed the quality of the literature. Review Manager 5.4 software was applied for data analysis. Twenty-nine RCTs with 1764 patients were included. According to the combined results, when compared with conventional treatment, HBOT significantly increased the complete healing rate of DFUs (46.76% vs. 24.46%, odds ratio [OR]: 2.83, 95% CI: 2.29-3.51, p < 0.00001) and decreased the amputation rate (26.03% vs. 45.00%, OR: 0.41, 95% CI: 0.18-0.95, p = 0.04), but the incidence of adverse events was significantly higher in patients (17.37% vs. 8.27%, OR: 2.49, 95% CI: 1.35-4.57, p = 0.003), whereas there was no significant difference in the mortality (6.96% vs. 12.71%, OR: 0.52, 95% CI: 0.21-1.28, p = 0.16). Our results suggest that HBOT is effective in increasing the complete healing rate and decreasing the amputation rate in patients with DFUs, but increases the incidence of adverse events, while it has no significant effect on mortality.

Alpha synuclein post translational modifications: potential targets for Parkinson's disease therapy?

Parkinson's disease (PD) is the most common neurodegenerative disorder with motor symptoms. The neuropathological alterations characterizing the brain of patients with PD include the loss of dopaminergic neurons of the nigrostriatal system and the presence of Lewy bodies (LB), intraneuronal inclusions that are mainly composed of alpha-synuclein (α-Syn) fibrils. The accumulation of α-Syn in insoluble aggregates is a main neuropathological feature in PD and in other neurodegenerative diseases, including LB dementia (LBD) and multiple system atrophy (MSA), which are therefore defined as synucleinopathies. Compelling evidence supports that α-Syn post translational modifications (PTMs) such as phosphorylation, nitration, acetylation, O-GlcNAcylation, glycation, SUMOylation, ubiquitination and C-terminal cleavage, play important roles in the modulation α-Syn aggregation, solubility, turnover and membrane binding. In particular, PTMs can impact on α-Syn conformational state, thus supporting that their modulation can in turn affect α-Syn aggregation and its ability to seed further soluble α-Syn fibrillation. This review focuses on the importance of α-Syn PTMs in PD pathophysiology but also aims at highlighting their general relevance as possible biomarkers and, more importantly, as innovative therapeutic targets for synucleinopathies. In addition, we call attention to the multiple challenges that we still need to face to enable the development of novel therapeutic approaches modulating α-Syn PTMs.

Parkinson's disease and diabetes mellitus: common mechanisms and treatment repurposing

In the last decade, attention has become greater to the relationship between neurodegeneration and abnormal insulin signaling in the central nervous system, as insulin in the brain is implicated in neuronal survival, plasticity, oxidative stress and neuroinflammation. Diabetes mellitus and Parkinson’s disease are both aging-associated diseases that are turning into epidemics worldwide. Diabetes mellitus and insulin resistance not only increase the possibility of developing Parkinson’s disease but can also determine the prognosis and progression of Parkinsonian symptoms. Today, there are no available curative or disease modifying treatments for Parkinson’s disease, but the role of insulin and antidiabetic medications in neurodegeneration opens a door to treatment repurposing to fight against Parkinson’s disease, both in diabetic and nondiabetic Parkinsonian patients. Furthermore, it is essential to comprehend how a frequent and treatable disease such as diabetes can influence the progression of neurodegeneration in a challenging disease such as Parkinson’s disease. Here, we review the present evidence on the connection between Parkinson’s disease and diabetes and the consequential implications of the existing antidiabetic molecules in the severity and development of Parkinsonism, with a particular focus on glucagon-like peptide-1 receptor agonists.

A Purification Method of 18F-FP-(+)-DTBZ via Solid-Phase Extraction With Combined Cartridges

Background: To optimize [¹⁸F] 9-fluoropropyl-(+)-dihydrotetrabenazine (¹⁸F-FP-(+)-DTBZ) purification via solid-phase extraction (SPE) with combined cartridges to facilitate its widespread clinical application. Methods: A modified SPE purification method, employing Sep-Pak PS-2 and Sep-Pak C18 cartridges, was used for the preparation of ¹⁸F-FP-(+)-DTBZ. This method was compared to the purification method of high-pressure liquid chromatography (HPLC) and SPE with one cartridge, following quality control test and positron emission tomography (PET) imaging in healthy volunteers and patients with parkinsn's disease (PD). Results: A SPE purification method integrating Sep-Pak PS-2 and Sep-Pak C18 cartridges was implemented successfully. The retention time of ¹⁸F-FP-(+)-DTBZ purified by HPLC, SPE with Sep-Pak PS-2, SPE with Sep-Pak C18, and SPE with combined use of Sep-Pak PS-2 and Sep-Pak C18 cartridges was 8.7, 8.8, 8.7, and 8.9 min, respectively. Fewest impurity peak was detected in ¹⁸F-FP-(+)-DTBZ purified by the SPE with combined use of Sep-Pak PS-2 and Sep-Pak C18 cartridges. This modified SPE purification method provided a satisfactory radiochemical yield of 29 ± 1.8% with radiochemical purity >99% and shortened synthesis time to 27 min. The brain uptake of ¹⁸F-FP-(+)-DTBZ purified by the modified SPE was comparable to that purified by HPLC in both healthy volunteers and PD patients. Conclusions: A SPE method integrating Sep-Pak PS-2 and Sep-Pak C18 cartridges for purification of ¹⁸F-FP-(+)-DTBZ may be highly suited to automatic synthesis for routine clinical applications, as it provides excellent radiochemical purity, high yield as well as operational simplicity.

Diabetes, insulin and new therapeutic strategies for Parkinson's disease: Focus on glucagon-like peptide-1 receptor agonists

Parkinson's disease and diabetes mellitus are two chronic disorders associated with aging that are becoming increasingly prevalent worldwide. Parkinson is a multifactorial progressive condition with no available disease modifying treatments at the moment. Over the last few years there is growing interest in the relationship between diabetes (and impaired insulin signaling) and neurodegenerative diseases, as well as the possible benefit of antidiabetic treatments as neuroprotectors, even in non-diabetic patients. Insulin regulates essential functions in the brain such as neuronal survival, autophagy of toxic proteins, synaptic plasticity, neurogenesis, oxidative stress and neuroinflammation. We review the existing epidemiological, experimental and clinical evidence that supports the interplay between insulin and neurodegeneration in Parkinson's disease, as well as the role of antidiabetic treatments in this disease.

GLP-1 peptide analogs for targeting pancreatic beta cells

Loss or dysfunction of the pancreatic beta cells or insulin receptors leads to diabetes mellitus (DM). This usually occurs over many years; therefore, the development of methods for the timely detection and clinical intervention are vital to prevent the development of this disease. Glucagon-like peptide-1 receptor (GLP-1R) is the receptor of GLP-1, an incretin hormone that causes insulin secretion in a glucose-dependent manner. GLP-1R is highly expressed on the surface of pancreatic beta cells, providing a potential target for bioimaging. In this review, we provide an overview of various strategies, such as the development of GLP-1R agonists (e.g., exendin-4), and GLP-1 sequence modifications for GLP-1R targeting for the diagnosis and treatment of pancreatic beta cell disorders. We also discuss the challenges of targeting pancreatic beta cells and strategies to address such challenges.