Analysis of N1‐acetyl‐N2‐formyl‐5‐methoxykynuramine/N1‐acetyl‐5‐methoxy‐kynuramine formation from melatonin in mice

Abstract: The interactions of melatonin, a potent endogenous antioxidant, with reactive oxygen species generate several products that include N¹‐acetyl‐N²‐formyl‐5‐methoxykynuramine (AFMK) and N¹‐acetyl‐5‐methoxy‐kynuramine (AMK). The physiological or pathological significance of AFMK/AMK formation during the process of melatonin metabolism in mammals has not been clarified. Using a metabolomic approach in the current study, the AFMK/AMK pathway was thoroughly investigated both in mice and humans. Unexpectedly, AFMK and AMK were not identified in the urine of humans nor in the urine, feces or tissues (including liver, brain, and eyes) in mice under the current experimental conditions. Metabolomic analysis did identify novel metabolites of AMK, i.e. hydroxy‐AMK and glucuronide‐conjugated hydroxy‐AMK. These two newly identified metabolites were, however, not found in the urine of humans. In addition, oxidative stress induced by acetaminophen in the mouse model did not boost AFMK/AMK formation. These data suggest that AFMK/AMK formation is not a significant pathway of melatonin disposition in mice, even under conditions of oxidative stress.     

The melatonin metabolite N1‐acetyl‐5‐methoxykynuramine facilitates long‐term object memory in young and aging mice

Melatonin (MEL) has been reported to enhance cognitive processes, making it a potential treatment for cognitive decline. However, the role of MEL’s metabolites, N1‐acetyl‐N2‐formyl‐5‐methoxykynuramine (AFMK) and N1‐acetyl‐5‐methoxykynuramine (AMK), in these effects are unknown. The current study directly investigated the acute effects of systemic MEL, AFMK, and AMK on novel object recognition. We also analyzed MEL, AFMK, and AMK levels in hippocampus and temporal lobe containing the perirhinal cortex following systemic MEL and AMK treatment. AMK administered post‐training had a more potent effect on object memory than MEL and AFMK. AMK was also able to rescue age‐associated declines in memory impairments when object memory was tested up to 4 days following training. Results from administering AMK at varying times around the training trial and the metabolism time course in brain tissue suggest that AMK’s memory‐enhancing effects reflect memory consolidation. Furthermore, inhibiting the MEL‐to‐AMK metabolic pathway disrupted object memory at 24 hours post‐training, suggesting that endogenous AMK might play an important role in long‐term memory formation. This is the first study to report that AMK facilitates long‐term object memory performance in mice, and that MEL crosses the blood‐brain barrier and is immediately converted to AMK in brain tissue. Overall, these results support AMK as a potential therapeutic agent to improve or prevent memory decline.     

Effect of genipin on cholestasis induced by estradiol‐17β‐glucuronide and lithocholate‐3‐O‐glucuornide in rats

Aim: Genipin is reported to stimulate the insertion of multidrug resistance protein 2 (Mrp2) in the bile canalicular membrane, thereby causing choleresis by the increased the biliary excretion of glutathione, which has been considered to be a substrate of Mrp2. In the present study, we examined the effect of genipin on cholestasis induced by estradiol‐17β‐glucuronide and lithocholate‐3‐O‐glucuronide, Mrp2 substrates, in rats. Further, the effect of genipin on the biliary excretion of substrates of P‐glycoprotein (P‐gp), vinblastine and erythromycin, was also studied. Methods: The effect of genipin infusion at the rate of 0.5 µmol/min/100 g on cholestasis induced by estradiol‐17β‐glucuronide (0.075 µmol/min/100 g for 20 min) and lithocholate‐3‐O‐glucuronide (0.15 µmol/min/100 g for 40 min) was studied. The effect of genipin infusion on the biliary excretion of a tracer dose of vinblastine and erythromycin infused at the rate of 0.1 µmol/min/100 g was also studied. Results: Genipin relieved estradiol‐17β‐glucuronide‐induced cholestasis, and cumulative biliary estradiol‐17β‐glucuronide excretion for 120 min was increased from 50 ± 20%–81 ± 20% dose. In contrast, genipin had no effect on lithocholate‐3‐O‐glucuronide‐induced cholestasis. Biliary excretion of a tracer dose of vinblastine and the maximum biliary excretion of erythromycin were significantly decreased by genipin. Conclusions: Genipin protected estradiol‐17β‐glucuronide‐induced cholestasis. The mechanism of the protection of cholestasis by genipin is unknown, but it is speculated to be due to a conformational change of P‐gp by genipin, in addition to the stimulation of Mrp2 insertion into the bile canaliculi.     

Melatonin enhances L‐DOPA therapeutic effects,helps to reduce its dose,and protects dopaminergic neurons in 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine‐induced parkinsonism in mice

L‐3,4‐dihydroxyphenylalanine (L‐DOPA) reduces symptoms of Parkinson's disease (PD), but suffers from serious side effects on long‐term use. Melatonin (10–30 mg/kg, 6 doses at 10 hr intervals) was investigated to potentiate L‐DOPA therapeutic effects in 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP)‐induced parkinsonism in mice. Striatal tyrosine hydroxylase (TH) immunoreactivity, TH, and phosphorylated ser 40 TH (p‐TH) protein levels were assayed on 7th day. Nigral TH‐positive neurons stereology was conducted on serial sections 2.8 mm from bregma rostrally to 3.74 mm caudally. MPTP caused 39% and 58% decrease, respectively, in striatal fibers and TH protein levels, but 2.5‐fold increase in p‐TH levels. About 35% TH neurons were lost between 360 and 600 μm from 940 μm of the entire nigra analyzed, but no neurons were lost between 250 μm rostrally and 220 μm caudally. When L‐DOPA in small doses (5–8 mg/kg) failed to affect MPTP‐induced akinesia or catalepsy, co‐administration of melatonin with L‐DOPA attenuated these behaviors. Melatonin administration significantly attenuated MPTP‐induced loss in striatal TH fibers (82%), TH (62%) and p‐TH protein (100%) levels, and nigral neurons (87–100%). Melatonin failed to attenuate MPTP‐induced striatal dopamine depletion. L‐DOPA administration (5 mg/kg, once 40 min prior to sacrifice, p.o.) in MPTP‐ and melatonin‐treated mice caused significant increase in striatal dopamine (31%), as compared to L‐DOPA and MPTP‐treated mice. This was equivalent to 8 mg/kg L‐DOPA administration in parkinsonian mouse. Therefore, prolonged, effective use of L‐DOPA in PD with lesser side effects could be achieved by treating with 60% lower doses of L‐DOPA along with melatonin.     

Reward‐based,task‐setting education strategy on glycemic control and self‐management for low‐income outpatients with type 2 diabetes

Aims/Introduction

The purpose of the study was to determine the feasibility and effect of a reward‐based, task‐setting strategy for low‐income outpatients with type 2 diabetes.

Materials and Methods

Indigent diabetes outpatients without glucometers were eligible to participate in this trial. A total of 132 cases were randomly recruited. Participants in group B used glucometers for self‐monitoring at no cost. Group A participants could keep the glucometers only if the glycosylated hemoglobin level declined compared with the baseline visit; for those not achieving a reduction in the glycosylated hemoglobin level, the glucometers would have to be returned. Group C served as the control group without self‐monitoring setout. Diabetes education was provided to all groups. Metabolic indices and self‐management were evaluated after 6 months of follow up.

Results

Group A had a significant decline in the glycosylated hemoglobin level (−0.97%) and medical costs (−159 yuan) compared with the baseline visit, whereas groups B and C had a decrease in the glycosylated hemoglobin levels alone (−0.62 and −0.57%, respectively). The body mass index did not change significantly in any group. There was a statistical difference in the glycosylated hemoglobin level of group A compared with groups B and C. Self‐management in group A improved the outcome relative to groups B and C.

Conclusions

This preliminary evidence suggests that the program is feasible, acceptable for improving patient self‐management, and cost‐effective in reducing the glycosylated hemoglobin level and medical costs.     

Recombinant IL‐7/HGFβ hybrid cytokine separates acute graft‐versus‐host‐disease from graft‐versus‐tumour activity by altering donor T cell trafficking

Given that donor T cells from a transplant contribute both the desired graft‐versus‐tumour (GVT) effect and detrimental graft‐versus‐host disease (GVHD), strategies to separate GVHD and GVT activity are a major clinical goal. We have previously demonstrated that in vivo administration of a recombinant (r)IL‐7/HGFβ hybrid cytokine, consisting of interleukin‐7 (IL‐7, IL7) and the β‐chain of hepatocyte growth factor (HGFβ), significantly inhibits the growth of cancer cells in murine tumour models. The antit‐umour effect of rIL‐7/HGFβ is related to a marked infiltration T cells in the tumour tissues. We have also shown that GVHD was not induced in rIL‐7/HGFβ‐treated T cell‐depleted allogeneic haematopoietic stem cell transplantation (HSCT) recipients. We show here that, in T cell‐replete allogeneic HSCT murine models, rIL‐7/HGFβ attenuated acute GVHD (aGVHD), while promoting GVT activity. This was related to an alteration of donor T cell trafficking, with an increased infiltration of donor T cells into tumour tissues and the lympho‐haematopoietic system but decreased number of the T cells in the GVHD target organs. Therefore, rIL‐7/HGFβ may offer a new tool to alleviate aGVHD while prompting GVT, and to study the molecular regulation of T cell trafficking.     

Encephalitis caused by human herpesvirus‐6B in pancreas‐after‐kidney transplantation

Human herpesvirus‐6 (HHV‐6) is a common pathogen among children, classically presenting with fever and rash that resolves without specific therapy. HHV‐6 can be reactivated in the immunosuppressed patient. After bone marrow and solid organ transplantation, HHV‐6 has been linked to various clinical syndromes, including undifferentiated febrile illness, encephalitis, myelitis, hepatitis, pneumonitis, and bone marrow suppression. However, HHV‐6 encephalitis after pancreatic transplant has rarely been reported. Early diagnosis and treatment of HHV‐6 encephalitis may be important for affected patients. We report the case of a 53‐year‐old pancreas‐after‐kidney transplant recipient who initially presented with high fever and confusion 3 weeks after operation. We managed to save the patient's life and preserve the pancreas graft function. We also review previously reported cases of HHV‐6B encephalitis in solid organ transplant recipients.