Effect of Difference of Proliferative Ability on Fragmentation of Hertwig＇s Epithelial Root Sheath

Objective To verify a novel hypothesis that it is the difference of proliferative ability between Hertwig＇s epithelial root sheath （HERS） and the neighboring mesenchyme that leads to fragmentation of HERS. Methods Developmental processes of rat mandibular first molars from postnatal （PN） 10 to 25 days were observed. HERS was traced by immunohistochemistry for keratin 14. The activity of proliferation was examined by immunohistochemistry and immunofluorescence for proliferating cell nuclear antigen （PCNA） at PN 10 and 25 days respectively. Results At PN 10, HERS grew to its maximum length and maintained integrity. Subsequently, along with tooth root elongation, HERS was gradually fragmented. Either at PN 10 or 25 days, there were more PNCA-positive cells in the neighboring mesenchyme than in the HERS. Conclusion During rat tooth root development, the neighboring mesenchyme possesses higher proliferative ability than HERS, which results in the fragmentation of HERS.     

Predicting intellectual outcome among children treated with 35-40 Gy craniospinal irradiation for medulloblastoma

Fifty children diagnosed with medulloblastoma completed 188 psychological evaluations using the Wechsler Intelligence Scales for Children (D. Wechsler, 1974, 1991) over a 7-year study period following 35-40 Gy postoperative craniospinal irradiation. Random coefficient models were used to predict the trend in the children's intellectual performance as a function of time since diagnosis, with both patient and treatment variables as parameters of this function. A quadratic model demonstrated a delay prior to decline in performance for older patients, whereas the younger patients showed an immediate loss of performance with a plateau at approximately 6 years postdiagnosis. A steeper decline was found for those with higher baseline performance. Clinicians may use the proposed predictive model to identify those patients who are at risk of significant intellectual decline.     

In utero methylmercury exposure differentially affects the activities of selenoenzymes in the fetal mouse brain

Pregnant ICR mice were subcutaneously injected with 0,5, or 3x3 mg Hg/kg of methylmercury (MeHg) on days 12,13, and 14(G12-14) of gestation and were sacrificed on G17. Activity of selenoenzymes, including glutathione peroxidase (GPx) and 5'- or 5-iodothyronine deiodinases (5'-DI, 5-DI), was determined in fetal brain and placenta. MeHg did not affect the concentration of Se in these tissues, while it significantly inhibited the activity of GPx in the fetal brain and placenta, but not in the maternal brain. Although the levels of thyroid hormones in the maternal and fetal plasma were not affected by MeHg, 5-DI decreased and 5'-DI increased in the fetal brain, as if they had responded to hypothyroidism. Because the level of T4 in the fetal plasma was not affected by MeHg, these changes in enzymatic activities may result in a harmful excess of T3 in the fetal brain. In addition, 5-DI activity was increased in the placenta of MeHg-treated mice. These effects of prenatal MeHg exposure on fetal and placental DIs differed from those of dietary-induced Se deficiency, where the activities of DIs were decreased or not affected. Further evaluation of the effect of MeHg on selenoenzymes, especially 5-DIs, is warranted.     

透皮芬太尼在术后止痛方面的应用

芬太尼是一人工合成的阿片类药 ,其分子量小( 336 5 )、脂溶性高、无局部刺激、止痛作用强(约为吗啡的 10 0倍 )等特点使其可以通过透皮药物输送系统 (ｔｒａｎｓｄｅｒｍａｌｔｈｅｒａｐｅｕｔｉｃｓｙｓｔｅｍ ,ＴＴＳ)给药。 1987年 ,Ｓｅｂｅｌ[1] 首次将芬太尼贴膜应用于临床。透皮芬太尼 (ｔｒａｎｓｄｅｒｍａｌｆｅｎｔａｎｙｌ,ＴＤＦ)中有缓释膜 ,能保证连续稳定的透皮给药。ＴＤＦ贴膜每平方厘米大约可运输芬太尼 2 5 μｇ/ｈ ,因此贴膜面积的增大将导致药物运输的增加。目前ＴＤＦ有 ( 10 ,2 0 ,30 ,4 0 )ｃｍ2 4种规格 ,其运…     

MyoD基因诱导大鼠心脏成纤维细胞分化为成肌细胞的实验研究

目的：探讨MyoD基因诱导大鼠心脏成纤维细胞分化为成肌细胞的可能性。方法：将MyoD基因重组腺病毒载体转染大鼠心脏成纤维细胞，观察转染后大鼠心脏成纤维细胞形态的变化；用RT-PCR和Western blot方法检测MyoD和肌细胞生成素的表达；免疫组化检测骨骼肌肌球蛋白和结蛋白的表达。结果：MyoD基因转染后的大鼠心脏成纤维细胞形态和排列方式发生明显变化；RT-PCR可检测出转染后细胞表达MyoD；Western blot结果表明转染后细胞表达MyoD和肌细胞生成素；免疫组化检测骨骼肌肌球蛋白和结蛋白表达均为阳性。结论：MyoD基因可诱导体外培养的大鼠心脏成纤维细胞分化为成肌细胞，为进一步研究MyoD对心肌损伤的修复作用奠定了基础。     

Improvement by phosphoramidon of damaged endothelial function in porcine coronary artery

BACKGROUND: The bradykinin (BK)-induced endothelium-dependent relaxation is impaired in the presence of elevated potassium concentration enhancing the vasospastic tendency of large coronary arteries. Inhibition of the angiotensin-converting enzyme responsible for bradykinin degradation was found to enhance the endothelium-dependent relaxation by BK. The aim of the present study was to investigate the effect of phosphoramidon, known to inhibit a BK-metabolizing neutral endopeptidase enzyme, on relaxation of porcine-isolated coronary artery in depolarizing solution. METHODS: Endothelium intact porcine coronary artery rings were studied in organ chambers. The rings were isometrically contracted with potassium chloride (30 mmol/L) and the response to BK (1 to 1,000 nmol/L)-induced relaxation was investigated in the presence of nitric oxide synthase inhibitor Nomega-nitro-L-arginine (300 micromol/L) alone and in combination with the cyclooxygenase inhibitor indomethacin (10 micromol/L), and that of the inhibitor of calcium-dependent potassium channels tetraethylammonium (7 mmol/L). Under these conditions, phosphoramidon (10 micromol/L), an inhibitor of a neutral endopeptidase enzyme (EC.3.4.24.11.), which is responsible for the degradation of BK, was used to enhance the endothelium-dependent relaxation. RESULTS: Phosphoramidon potentiated the maximum vasorelaxant effect of BK in Nomega-nitro-L-arginine (control 26.6%+/-10.86% versus phosphoramidon 49.05%+/-4.52%; n = 6, p < 0.05) or in Nomega-nitro-L-arginine + indomethacin-pretreated rings (control 20.7%+/-9.92% versus phosphoramidon 42.0%+/-12.26%; n = 5, p < 0.05) and this increased vasodilation was not modified by tetraethylammonium. CONCLUSIONS: In the present study phosphoramidon potentiated the effect of BK in the absence of nitric oxide and prostaglandins in porcine-isolated coronary artery. This effect did not depend on tetraethylammonium-sensitive potassium channels. Phosphoramidon may be a useful pharmacologic tool for preserving the vasorelaxing capacity of coronary arteries after cardioplegia.     

A pilot study on vitrectomy combined with scleral shortening for eyes with myopic macular retinoschisis——2y follow-up results

AIM:To evaluate the effect of vitrectomy combined with scleral shortening for eyes with myopic macular retinoschisis.METHODS:Thirty-seven patients with myopic macular retinoschisis who underwent pars plana vitrectomy(PPV)combined with scleral shortening were reviewed.Axial length(AL),the height of macular retinoschisis,the height of retinal detachment if existed,the diameter of macular hole if existed and best corrected visual acuity(BCVA)were obtained.The preoperative and postoperative parameters were compared.RESULTS:At postoperative 24 mo,the mean AL and height of macular retinoschisis were reduced significantly by 0.79 mm and 256.51μm(t=8.064,P<0.0001;Z=-5.086,P<0.0001)respectively.In addition,the mean height of retinal detachment and diameter of macular hole were also reduced significantly by 365.38μm and 183.68μm(Z=-4.457,P=0.000008;Z=-2.983,P=0.003)respectively.Meanwhile,the postoperative BCVA was improved markedly(Z=-2.126,P=0.033).CONCLUSION:Vitrectomy combined with scleral shortening is an effective surgical method for eyes with myopic macular retinoschisis,whether or not macular hole and retinal detachment are present.     

Short-term environmental enrichment exposure induces proliferation and maturation of doublecortin-positive cells in the prefrontal cortex

Previous studies have demonstrated that doublecortin-positive immature neurons exist pre- dominantly in the superficial layer of the cerebral cortex of adult mammals such as guinea pigs, and these neurons exhibit very weak properties of self-proliferation during adulthood under physiological conditions. To verify whether environmental enrichment has an impact on the proliferation and maturation of these immature neurons in the prefrontal cortex of adult guinea pigs, healthy adult guinea pigs were subjected to short-term environmental enrichment. Animals were allowed to play with various cognitive and physical stimulating objects over a period of 2 weeks, twice per day, for 60 minutes each. Immunofluorescence staining results indicated that the number of doublecortin-positive cells in layer II of the prefrontal cortex was significantly increased after short-term environmental enrichment exposure. In addition, these doublecortin-positive cells co-expressed 5-bromo-2-deoxyuridine （a marker of cell prolifera- tion）, c-Fos （a marker of cell viability） and NeuN （a marker of mature neurons）. Experimental findings showed that short-term environmental enrichment can induce proliferation, activation and maturation of doublecortin-positive cells in layer II of the prefrontal cortex of adult guinea pigs.     

Comparison of 4 functional indexes in psoriatic arthritis with axial or peripheral disease subgroups using Rasch analyses

OBJECTIVE: Rasch item response theory analysis is essential in evaluating measurement tools in specific disease cohorts. We compared the performance of 4 functional indexes in patients with psoriatic arthritis (PsA) in axial or peripheral disease subgroups. METHODS: A cross-sectional study was performed in a single center. Functional outcomes assessed by the Health Assessment Questionnaire (HAQ), Bath Ankylosing Spondylitis Functional Index (BASFI), Dougados Functional Index (FI), and the physical functioning scale of the Medical Outcome Study Short-form 36 (SF-36-PF) were analyzed by the Rasch model for item fit, item separation, measurement span, and distribution properties. Patient subgroups with axial or peripheral disease were analyzed for differential item functioning (DIF). RESULTS: One hundred eight patients with PsA were assessed. The 4 functional indexes were highly correlated with each other and moderately correlated with patients' perception of health and pain scores. Floor effects were less marked in SF-36-PF. The 4 indexes satisfied the unidimensionality assumption of the Rasch model. HAQ and SF-36-PF had better information-weighted fit statistics (INFIT) and outlier-sensitive (OUTFIT) statistics. HAQ had the poorest item separation. SF-36-PF had the highest item separation (6.99), reliability (0.85), and the longest span of item threshold (9.03 logits). Only 1 and 2 items in BASFI and Dougados-FI had DIF in patients with sacroiliitis. CONCLUSION: HAQ, BASFI, Dougados-FI, and SF-36-PF provide unidimensional measures of functional disability in PsA. SF-36-PF was the best in terms of less floor effect, highest item separation, longest span of item threshold, and better distributional properties. BASFI and Dougados-FI behaved similarly in patients with and without sacroiliitis and conferred no superiority in patients with axial disease.