Clinical And Mechanism Study On Energy Metabolism Disorders In Patients With Narcolepsy With Cataplexy

Part Ⅰ.Study of BMI Index Change and Basal Metabolic Rate in Childhood Narcolepsy with CataplexyObjective: Observe the BMI change and basal metabolic rate during short stage after childhood narcolepsy with cataplexy(NC)onset,aim to explore the reasons for rapid weight gain.Methods: This study consists of two parts.1).Analysis of weight gain and BMI index change,case-control study.From the database of narcolepsy of the department of neurology in Changzheng hospital,screened 65 cases(male 39,female 26)of childhood narcolepsy,whose BMI index were tracked and measured more than 3 years.The cases with disease courses less than 1 year from first visit and age not more than 15 years old were included,mean age 11(4-15)years and met the narcolepsy diagnostic criteria according to ICSD-2.The BMI index measured every 6 months were analyzed.Convenient sampling procedure was utilized to select 81 healthy school children(male 43,female 38)as controls.2).Comparative study on basal metabolic rate,case-control study.Twenty eight children with NC(male 18,female 10),with disease course less than 2 years were recruited.Twenty two healthy controls(male 15,female 7)were matched with age,gender and BMI.Parameters of the basal metabolic rate were obtained via the portable metabolic system(Cosmed k4b2)in fasting,bed resting quiescent condition.And rectal temperature was measured.Statistical analysis include repeated-measurement ANOVA,independent samples t test,Wilcoxon rank sum test and chi square test.Results: 1.A total of 65 children with NC were interviewed,49(75.38%)children presented significant weight gain after the first symptom emerged 4.32±1.53 months later.After 16.14±3.91 months,weight change tended to be normal.At the end of 3-year follow up period,the proportion of overweight and obesity in patients group were significant higher than control group(p=0.002,p<0.001).2.After included study 6,12 and 18 months,the BMI growth rates were significantly higher than those in controls(3.777±0.578 vs.1.986±0.463,p=0.001;2.710±0.406 vs.1.983±0.451,p=0.001;2.254±0.317 vs.1.996±0.430,p=0.001,respectively).After 24 months,there was no significant difference between two groups in BMI growth rate(1.927±0.287 vs.1.877±0.478,p=0.460).While after 30 and 36 months,the BMI growth rates of patients were less than those of controls(1.669±0.220 vs.1.888±0.582,p=0.005;1.722±0.247 vs.1.931±0.437,p<0.001).3.Basal metabolic rate determination showed: There were significant differences in EEkc(kcal/day),EEbsa(kcal/m2/day),EEkg(kcal/kg/day)and METs(1611.12±292.32 vs.1927.51±342.05,p=0.011;1177.45±135.22 vs.1411.37±322.45,p=0.010;34.54±6.185 vs.47.88±12.19,p=0.003;1.42±0.25 vs.1.98±0.47,p=0.002,respectively).Conclusions: There was an appearance of rapid weight gain after childhood NC onset,which was closely related to the disease course.The growth rate of BMI showed a tendency to deline during observation period.Basal metabolic rate was reduced in childhood NC,suggesting that basal metabolic rate reducing may be one of the important reasons of rapid weight gain in NC patients.Part Ⅱ.Relation between Fatigue and Serum Lactic Acid/LDH in Patients with NarcolepsyObjective: To assess the degree of fatigue in patients with narcolepsy,and explore the correlation between fatigue and lactic acid/lactate dehydrogenase in patients with NC.Methods: Case-control study.A total of 91 patients with narcolepsy(male 58,female 33,mean age 18.35±3.04 years)were included from 2013.1~2014.10.The patients with narcolepsy were divided into two subgoups,NC subgroup 59(male 40,female 19),Nwo C subgroup 32(male 23,female 9).The diagnostic criteria for narcolepsy was shown in part I.Thirty seven healthy volunteers(male 26,female 11,mean age 19.48±3.56 years)with age,sex and BMI matched were enrolled.Degree of sleepiness was scored with the Epworth sleepiness scale.Fatigue was assessed via Chalder-14 fatigue scale.And the severity of cataplexy attack was evaluated.Parameters of sleep were obtained through PSG monitoring and MSLT.Lactic acid and lactic acid dehydrogenase were detected.Lactic acid dehydrogenase isoenzyme activity was separated using polyacrylamide gel electrophoresis.Statistical analyses included independent samples t test,Mann-Whitney U test,ANOVA with post hoc LSD test,pearson or spearman correlation analysis and multiple linear stepwise regression analysis.Results: 1.In 91 patients with narcolepsy,the fatigue total score of 69 patients(75.82%)was more than 5 scores.The total score,physical score and mental score of patients group were obviously higher than controls(6.20±2.38 vs.2.35±0.86,p<0.001;4.53±1.87 vs.1.43±0.60,p<0.001;1.67±0.99 vs.0.89±0.70,p=0.002).The fatigue total scores in NC subgroup,Nwo C subgroup and control group were significantly successively decreased(6.97±2.75 vs.5.18±1.26 vs.2.35±0.86,p<0.001,respectively).Physical scores were also have obvious differences among three groups and showed a tendency to descend from NC subgroup,Nwo C subgroup to control group(5.14±2.03 vs.3.73±1.28 vs.1.43±0.60,p<0.001,respectively).2.Compared with control group,lactic acid in patients group increased significantly,(3.27±0.82mmol/L vs.1.90±0.38mmol/L,p<0.001).The levels of lactic acid in NC subgroup,Nwo C subgroup and controls were successively decline(3.45±0.78 vs.3.04±0.82 vs.1.90±0.38,p<0.001,respectively).3.The total LDH of NC and Nwo C subgroups were both increased significantly compared with control group(NC 203.38±50.40 U/L,Nwo C 197.16±12.78 U/L,control 178.24±47.81 U/L);LDH3,LDH4 and LDH5 of NC were significantly higher than those of control group(p<0.01).Likwise,LDH3 and LDH4 of Nwo C subgroup were also higher than those of control group(p<0.05).4.Correlation analysis showed that fatigue total score was associated with BMI,lactic acid,LDH,LDH3,LDH4,LDH5(correlation coefficients and p values: r=0.362,p=0.009;r=0.562,p<0.001;r=0.505,p<0.001;r=0.445,p=0.001;r=0.613,p<0.001;r=0.559,p<0.001,respectively).5.Multiple linear stepwise regression analysis showed that lactic acid,LDH4 and LDH5 may be as predictors for fatigue in patients with narcolepsy,lactic acid β=0.575,p<0.001,LDH4 β=0.166,p=0.043,LDH5 β=0.171,p=0.037.Conclusions: The fatigue degree and incidence in patients with narcolepsy were significantly higher than controls.The levels of lactic acid,LDH and LDH3、LDH4、LDH5 were considerably increased.There were strong correlations between fatigue and lactic acid,LDH4,LDH5.Lactid acid,LDH4 and LDH5 could be used as predictors for fatigue in patients with narcolepsy.Part Ⅲ.Pilot Study on Changes of Serum Lactic Acid Levels and Damage of Skeletal Muscle Mitochondria in Patients with Narcolepsy with CataplexyObjective: Aim to investigate the changes of lactic acid level pre-and post-exercise in patients with NC,explore the relationship between the changes and parameters related with sleep.And to observe the changes of mitochondria in patients with narcolepsy.Methods: This study consists of two parts.1).Study on serum lactic acid level before and after aerobic exercise,case-control study.Seventy four NC patients(male 56,female 18,mean age 18.00±12.24 years)were included from 2013.1~2014.10.Thirty five healthy individuals with age,sex matched were recruited as control subjects.All of the cases were examined via PSG and MSLT,and the symptoms were evaluated and met the diagnostic criteria for NC.The aerobic exercise involved jogging for 15 minutes.The running speed was about 100 steps per minute,under the control of a pedometer(Omron,China,lnc).The runningstep width of each subject was measured prior to the exercise session.Before and after aerobic exercise,serum lactic acid levels were detected.2).Skeletal muscle mitochondria ultrastructure observation by transmission electron microscopy.Three male patients with NC and 2 male healthy subjects were conducted by muscle biopsy examination.The skeletal muscles were taken from the biceps or deltoid,observed under transmission electron microscope.The damaged mitochondria were evaluated using a semi-quantitative method.Results: 1.Serum lactic acid levels before and after exercise were significantly higher than those of controls(2.21±0.51 vs 1.97±0.39 mmol/L,p=0.017;7.46±3.28 vs 3.31±0.74 mmol/L,p<0.001,respectively).The ratio of lactic acid level post-/pre-exercise was also higher than that of controls(3.5±1.65 vs.1.71±0.41,p<0.001).2.The cutoff value of lactic acid before exercise was 2.35 mmol/L,AUC 0.658.Cutoff value of lactic acid after exercise was 4.95 mmo/L,AUC 0.919.Cutoff value of lactic acid ratio before and after exercise was 2.30,AUC 0.888.3.Transmission electron microscopy examination showed 1)damaged mitochondria in different levels,ranging from a blurred image of the cristae of the mitochondria,to partial disappearance of the cristae,to vacuolation of some mitochondria;2)the accumulation of glycogen granules diffused among myofibrils and myofilaments;and 3)lipidosis in mitochondria.There was an obvious difference in the proportion of damaged mitochondria via semi-quantitative assessment between NC group and controls(p<0.001).Conclusions: The lactic acid of pre-and post-exercise and lactic acid ratio of NC patients were significantly higher than those of healthy controls.Lactic acid after aerobic exercise and the ratio of post-/pre-exercise had higher sensitivity and specificity to distinguish between patients with narcolepsy and healthy individuals,and maybe used as auxiliary observation indexes for narcolepsy.Mitochondria had visible structural abnormalities in NC patients.The rising of serum lactic acid level may be due to the structure damage of muscle mitochondria.