An experimental study addressing the promotion of mandibular defect repair through the intermittent subcutaneous injection of parathyroid hormone.

PURPOSE: Parathyroid hormone (PTH) is a major regulator of bone metabolism. Various animal studies and clinical trials have addressed the treatment of osteoporosis and fracture healing with the intermittent administration of PTH, whereas few studies have investigated the effects of PTH on mandibular defect repair. This study sought to examine the feasibility of using recombinant human PTH (rhPTH) to promote the repair of mandibular defects and to provide a preliminary investigation of the underlying mechanisms of this phenomenon. MATERIALS AND METHODS: A mandibular defect model was established using Japanese white rabbits. The experimental animals were randomly divided into a control group that received postoperative subcutaneous injections of normal saline on alternate days and an experimental group that received postoperative subcutaneous injections of rhPTH 25 µg on alternate days. The experimental animals were sacrificed at 1, 2, 3, and 4 weeks after the operation to perform x-ray imaging and bone histomorphometric examinations of the defect areas. Changes in serum levels of bone-specific alkaline phosphatase (bALP) and osteoprotegerin (OPG) over time were examined. RESULTS: Compared with the control group, the experimental group exhibited newly generated bone matrix in the mandibular defect area at earlier stages. In the experimental group, the bone trabeculae were arranged in an orderly manner, and uniform calcification was observed. Marked hyperplasia of osteoblasts was observed in the new bone tissue of the experimental group, but significantly less hyperplasia of osteoblasts was observed in the control group. In the 2 groups, the average serum bALP and OPG levels increased after the operation and then gradually decreased. In the experimental group, levels of bALP and OPG at 1 week and 2 weeks after the operation were significantly different from preoperative levels. In the control group, the OPG level at 2 weeks after the operation was significantly different from the preoperative OPG level. A comparison of serum bALP and OPG levels at each examined time point showed no significant difference between the 2 groups. CONCLUSION: The intermittent subcutaneous injection of rhPTH 25 µg/day promotes the healing of mandibular defects in rabbits. The application of rhPTH may facilitate mandible regeneration by increasing quantities of osteoblasts, accelerating bone turnover metabolism, and upregulating OPG levels.

[An epidemiological survey of the prevalence of thyroid diseases in mild iodine deficiency city after salt iodization].

OBJECTIVE: To investigate the current status of iodine nutrition and the prevalence of thyroid diseases in Guiyang, a mild iodine deficiency city practiced salt iodization for 25 years. METHODS: A representative sample of 1509 adults aged 20 years old or above in Guiyang, selected by a multistage stratified sampling method, participated in the study. After an overnight fasting, serum thyroid hormones, serum thyroid autoantibodies, and urine iodine were measured. B-mode ultrasonography of the thyroid was performed in the population. Meanwhile, urine iodine of 80 children aged 8 - 10 years old in the same community were measured after an overnight fasting. RESULTS: The median of 8-10 years old children's urinary iodine was 228.7 µg/L. The prevalence of overt hypothyroidism, subclinical hypothyroidism, overt hyperthyroidism and subclinical hyperthyroidism was 1.79%, 14.12%, 1.52% and 1.06% respectively. The prevalence of subclinical hypothyroidism was significantly higher than overt hypothyroidism (P < 0.05) and was significantly higher in female than that in male (P < 0.05). The prevalence of positive thyroid peroxidase antibody, positive thyroglobulin antibody and autoimmune thyroiditis was 14.38%, 13.59% and 4.44% respectively, which were significantly higher in female than that in male (all P values < 0.05). The prevalence of diffuse goiter and nodular goiter was 0.86% and 0.20% respectively, with a significant difference (P < 0.05). CONCLUSION: After 25 years of salt iodization, the iodine nutrition in Guiyang is more than adequate with high prevalence of overt hypothyroidism, subclinical hypothyroidism and autoimmune thyroiditis.

[Survey of vitamin D status in 700 healthy adult males in Guiyang, China].

OBJECTIVE: To evaluate the vitamin D status of healthy adult males living in Guiyang. METHODS: A total of 700 healthy volunteers aged 20 - 79 years were selected randomly from a community in Guiyang by stratified sampling method. Questionnaires for living habits and fasting blood samples were collected in the morning from November 2009 to January 2010. The serum concentrations of 25-hydroxyvitamin D were measured by the DiaSorin radioimmunoassay kit. RESULTS: The mean levels of serum 25(OH)D was (21 ± 10) µg/L. And the percentages of vitamin D deficiency (25(OH)D < 20 µg/L), insufficiency (20 µg/L ≤ 25(OH)D < 30 µg/L) and sufficiency (25(OH)D ≥ 30.0 µg/L) were 315(50.2%), 202 (32.2%) and 110(17.6%)respectively. The concentrations of serum 25(OH)D in young, middle-aged and old adults were (18 ± 10) µg/L, (24 ± 10) µg/L and (22 ± 8)µg/L respectively. The serum level of 25(OH)D was lower in the smokers than that in the non-smokers (20 µg/L vs 22 µg/L, P = 0.003). The serum concentrations of 25(OH)D were (24 ± 10) µg/L, (23 ± 10) µg/L, (22 ± 9) µg/L and (18 ± 9) µg/L in education level (≤ 6, 7 - 9, 10 - 12 and ≥ 10 years in school) respectively. Significant inverse correlations existed between the concentrations of serum 25(OH)D and the education levels (r = -0.138, P = 0.000). CONCLUSION: The prevalence of hypovitaminosis D is common in healthy adult males in Guiyang, especially among the youth, smokers and higher educated groups.