BACKGROUND: Diabetes causes abnormal insulin like growth factor-1 (IGF-1) gene expression, which contributes to initiation and development of peripheral neuropathy.OBJECTIVE: To investigate the efficacy of a single dose of methylcabalamin on prevention of experimental diabetic neuropathy and the possible molecular mechanism of its involvement in IGF-1 gene expression.DESIGN: Completely randomized and controlled experiment.SETTING: Endocrinology Department of the First Affiliated Hospital of Nanjing Medical University.MATERIALS: The study was carried out in an Animal Center of Nanjing Medical University. Totally 80 male Sprague Dawley rats (sanitary degree)were randomly selected.METHODS: ① Totally 64 rats were chosen to be induced diabetic. They were injected intravenously with alloxan dissolved in saline solutions, at the dose of 240 mg/kg. ② Of 16 rats were chosen as normal control group who were injected intravenously with equivalent volume of saline solution. ③ Of 64 established diabetic rats were treated with daily subcutaneous injection of pork regular insulin in combination of protamine zinc insulin (2:1) then further divided into 2 groups as insulin-treatment diabetic control groups based on different blood glucose levels: group 1 with relatively better control of diabetes, group 2 with relatively worse control of diabetes, with 32 rats in each group. Totally 16 rats of each group were treated with methylcobalamin injection intramuscularly with 500 μg/kg body weight, thus correspondingly divided into insulin +methylcobalamin group 1 and insulin+methylcobalamin group 2. The remaining 16 rats of each group as respective insulin-treatment diabetic control groups were treated with equivalent volume of saline. ④ Initiate weight and end weight were measured at beginning of the experiment and after diabetic model was established. Glucose oxidase was used to detect glucose level. 1-deoxy-1-malin was used to detect fructose level. ⑤ Parameters were measured as follows: Sensory/motor nerve conduction velocity (SNCV, MNCV) and evoked potential amplitude (EPA) of sciatic nerves detected by evoked electromyogram; IGF-I mRNA by reverse-transcriptase polymerase chain reaction (RT-PCR); IGF-1 peptide by enzyme-linked immunosorbent assay (ELISA). ⑥ One-way analysis of variance was used to analyze the Significance of differences among groups.MAIN OUTCOME MEASURES: ① Tissue IGF-1 mRNA/ IGF-1 peptide, electrophysiological data of individual groups at different points of the experiment. ② Comparison between individual groups in glucose metabolic parameters and body weights at different points of the experiment.RESULTS: Three rats died for diabetic infection or other acute complications and only 77 rats were included in the final statistical analysis.① Body weight and glucose metabolic parameter changes: After diabetic model, glucose, fructose level and body weight change between methylcobalamin+insulin treated groups and insulin treated groups were not significant. ② IGF-1 mRNA/peptide changes: Tissue IGF-1 mRNA increased significantly in methylcobalamin + insulin treated groups than that in insulin treated groups, respectively (P ＜ 0.05-0.01). Two weeks after diabetic model was established, the sciatic tissue IGF-1 mRNA contents were obviously higher in methylcobalamin + insulin treated group 1 than that in insulin treated group 1 (P ＜ 0.05), but not significantly different from that in NC group; Similarly, tissue IGF-1 mRNA contents were obviously higher in methylcobalamin + insulin treated group 2 than that in insulin treated group 2 (P ＜ 0.05), but lower than that in NC group (P ＜ 0.01); Month 2, tissue IGF-1 contents in methylcobalamin+ insulin treated groups were lower signiiicantly than NC groups, but higher than insulin treated groups (P ＜ 0.05-0.01). By month 3, IGF-1 mRNA level in methylcobalamin+ insulin treated group 2 was not significantly different from that in insulin treated group 2. The IGF-1 peptide levels in nerve tissue changed approximately parallel to IGF-1 mRNA level over time course. ③ Nerve electrophysiological data changes: Month 2 and 3, SNCV, MNCV and EPA were significantly higher in methylcobal-amin+ insulin treated group 1 than in insulin treated group 1 (P ＜ 0.05);Month 2, SNCV and EPA were higher in methylcobalamin+ insulin treated group 2 than in insulin treated group 2 (P ＜ 0.05); Month 3, SNCV, MNCV and EPA were significantly lower in methylcobalamin + insulin treated group 2 than in control group (P ＜ 0.05-0.01), whereas no difference was observed between methylcobalamin + insulin treated group 2 and insulin treated group 2.CONCLUSION: ① Methylcobal has not effect on blood glucose. ②Methylcobal could prevent occurrence of experimental neuropathy through its effect on nerve IGF-1 gene expression of diabetic rats. ③ A better efficacy could be achieved by Methylcobal with a good control of blood glucose level in prevention of diabetic peripheral neuropathy.

OBJECTIVETo explore the role of insulin-like growth factor 1 (IGF-1) gene expression abnormality in neurotrophic causes of diabetic peripheral neurophathy.

METHODSDiabetes was induced in Sprague Dawley rats by alloxan. The parameters were measured as follows: IGF-1 mRNA by revere transcriptase-polymer chain reaction (RT-PCR); IGF-1 peptide by enzyme-linked immunosorbent assay (ELISA); electrophysiological parameters of nerves by evoked electromyogram; morphometric evaluation of sciatic nerves under light microscope and transmission electron microscope.

RESULTSDuring early diabetic stage, IGF-1 mRNA [(0.430+/-0.031) vs. (0.370+/-0.016), P<0.01, (0.430+/-0.031) vs. (0.280+/-0.010), P<0.001, respectively], IGF-1 peptide contents [(38.44+/-3.60) ng/mg vs. (30.06+/-2.41) ng/mg, P<0.01, (38.44+/-3.6) ng/mg vs. (3.71+/-2.70) ng/mg P<0.001, respectively] in sciatic nerve tissue reduced in diabetic rats with hyperglycemia and varied with severity of state when compared with non-diabetic control rats, and further gradually down-regulated in the diabetic rats with duration of diabetes [IGF-1 mRNA (0.320+/-0.021) to approximately (0.230+/-0.060); IGF-1 peptide (28.80+/-3.30) to approximately (19.51+/-1.80) ng/mg]. Furthermore, they correlated with nerve functional (sensory nerve conduction velocity: r=0.741, P<0.001; amplitude of evoked potential: r=0.716, P<0.001, respectively) and structural abnormality (axonal area r=0.81, P<0.001) of sciatic nerve. No difference was found in the above parameters between diabetic rats with euglycemia and non-diabetic control group.

CONCLUSIONIGF-1 gene expression in tissues was down-regulated from early diabetic stage, and varied with the severity and duration of diabetic state. The decrement in IGF-1 level might contribute to the initiation and development of diabetic neuropathy via autocrine or paracrine pathway.

Alloxan ; Animals ; Diabetes Mellitus, Experimental ; etiology ; metabolism ; Diabetic Neuropathies ; etiology ; metabolism ; Electrophysiology ; Evoked Potentials ; Insulin-Like Growth Factor I ; biosynthesis ; genetics ; RNA, Messenger ; biosynthesis ; Rats ; Rats, Sprague-Dawley ; Sciatic Nerve ; physiopathology

BACKGROUND:Resection of femoral neck in the conventional total hip replacement greatly influences the equilibrium of forces jn the proximal fetour and causes disequilibrium of bone reconstruction,easily resulting in bone absorption,prosthesis loosening and dislocation.OBJECTIVE:To investigate the biocompatibility between materials and host in the total hip replacement with femoral neck preserved.DESIGN,TIME AND SETTING:A retrospective case analysis was performed in the Department of Orthopedics,the 180 Hospital of Chinese PLA between September 2000 and December 2006.PARTICIPANTS:Twenty-five patients.10 males,15 females,aged 47 years old(range 31-56 years old)were recruited for this study.Twelve patients suffered from femoral head necrosis-caused hip joint disease and osteoarthrosis(bilaterally affected in 5 patients),eight femoral head necrosis(femoral head necrosis subsequent to femoral neck fracture healing in 2 patients),three acetabular dysplasia necrosis of femoral head,and two infra-head femoral neck fracture nonunion.The course of disease averaged 6 years old ranging from 2-10 years.METHODS:Modified hip ioint posterior approach was used to expose the hip joint.Femoral head was resected from the femoral head-neck iuncture.Cartilago acetabularis was stripped and then artificial acetabulum was installed.Femoral proximal medullary cavity was expanded.Artificial femoral head was installed.Finally,all artificial joints were reduced.MAIN OUTCOME MEASURES:(1)Biocompatibility between prosthesis and host.(2)Function recovery of hip joint.RESULTS:All wounds were primarily healed.Patients were followed up for 0.5-6 years on average.Follow-up results demonstrated good hip joint motion and normal walking gait.X-ray showed well-positioned artificial hip joint,absence of prosthesis loosening and dislocation,as well as good femoral neck sclerotin.CONCLUSl0N:The preservation of femoral neck in total hip replacement is fit to the physiological compliance of proximal femar and prevents osteoporosis-induced prosthesis loosening and dislocation in the proximal femur.