Regular Glucosamine Use May Have Different Roles in the Risk of Site-Specific Cancers: Findings from a Large Prospective Cohort.

BACKGROUND: Previous studies indicated that glucosamine supplements may have a general anticancer effect. This study aimed to assess whether the potential effect differs across different types of cancers in a large prospective cohort study. METHODS: All participants from the UK Biobank who were free of cancers and had complete information on glucosamine use at baseline were included and followed up from 2006 until 2021. Cox proportional hazards models were used to assess the associations between regular glucosamine use and different site-specific cancers. Subgroup analyses were performed to explore potential interactions. Several sensitivity analyses were conducted to assess the robustness of the main findings. RESULTS: A total of 450,207 eligible participants (mean age: 56.2 years; females: 53.3%) were included, of whom 84,895 (18.9%) reported regular glucosamine use at baseline. During a median of 12.5 years follow-up, glucosamine use was significantly associated with an increased risk of overall cancer [HR, 1.04; 95% confidence interval (CI), 1.01-1.06], skin cancer (HR, 1.11; 95% CI, 1.07-1.15), and prostate cancer (HR, 1.07; 95% CI, 1.01-1.13), and with a reduced risk of lung cancer (HR, 0.88; 95% CI, 0.79-0.97) after adjusting for potential confounders. Statistical interaction was observed for gender, age, and education for the association of glucosamine use with overall cancer risk (all Pinteraction < 0.027). These results remained unchanged in the sensitivity analyses. CONCLUSIONS: Regular glucosamine use was associated with lower risk of lung cancer but higher risk of skin cancer, prostate cancer, and overall cancer. IMPACT: The roles of glucosamine use potentially differ in the development of different site-specific cancers.

Enzymatic hydroxylation of L-pipecolic acid by L-proline cis-4-hydroxylases and isomers separation.

OBJECTIVES: Establish a complete and efficient method for the preparation of cis-5-hydroxy-L-pipecolic acids (cis-5HPA), including biotransformation and isomers separation and purification. RESULTS: For non-heme Fe(II)/α-KG-dependent dioxygenases, α-ketoglutarate (α-KG) has great influence on the stability of Fe(II) ions, which is also the basic of the hydroxylation reaction to the substrate. L-pipecolic acids (L-Pip) was converted to cis-5HPA by whole-cell catalysis in water, which can reduce the loss of Fe(II) ions. 120 mM L-Pip can be transformed to 93% via cell and Fe(II) ions continuous supplementation under the reaction system optimization (the molar ratio of ascorbic acid/FeSO4·7H2O and α-KG/L-Pip were 8:1 and 1:1, respectively). After the catalytic reaction, the amino protection strategy was adopted to improve the resolution of isomer products on silica gel chromatography, and the amino protected cis-5HPA was obtained with a yield of 86.7%. CONCLUSIONS: We established a method which is promising to be used for cis-5HPA largescale preparation. It also provides a suitable reference for this type of enzyme-catalyzed reaction and the hydroxy pipecolic acid isomers separation.

Insulin resistance and protein metabolism in chronic hemodialysis patients.

OBJECTIVE: Loss of lean body mass (sarcopenia) is associated with increased morbidity and mortality in patients receiving chronic hemodialysis (CHD). Insulin resistance (IR), which is highly prevalent in patients receiving CHD, has been proposed to play a critical role in the development of sarcopenia. The aim of this study was to examine the effect of IR on amino acid metabolism in patients receiving CHD. DESIGN: This was a cross-sectional study. SUBJECTS: The study included 12 prevalent (i.e., patients that have been on dialysis for more than 90 days) African American patients receiving CHD. METHODS: IR was measured as glucose disposal rate (GDR) determined from hyperinsulinemic euglycemic clamp (HGEC) studies performed 3 consecutive times. Plasma amino acid (AA) concentrations were measured by real-time high-performance liquid chromatography (HPLC) throughout the clamp study. The primary outcome was percentage change in leucine concentrations during the clamp study. The main predictor was the GDR measured simultaneously during the HGEC studies. Mixed model analysis was used to account for repeated measures. RESULTS: All individual AA concentrations declined significantly in response to high-dose insulin administration (P < .001). There was a significant direct association between GDR by HECG studies and the percentage change in leucine concentration (P = .02). Although positive correlations were observed between GDR values and concentration changes from baseline for other AAs, these associations did not reach statistical significance. CONCLUSIONS: Our results suggest that the severity of IR of carbohydrate metabolism is associated with a lesser decline in plasma leucine concentrations, suggesting a similar resistance to protein anabolism. Insulin resistance represents a potential mechanism for sarcopenia commonly observed in patients receiving CHD.