A sensitive biochemical assay for the detection of uracil

We have developed a sensitive new assay for the detection of uracil in DNA. The assay described here is an adaptation to the highly sensitive aldehydic slot blot (ASB) assay developed by Nakamura et al. (Nakamura et al. 1998: Cancer Res 58:222-225) in which aldehydic DNA lesions (ADLs) are detected through binding of a biotinylated aldehydic reactive probe to DNA. The uracil DNA glycosylase (UDG)-coupled ASB assay uses uracil-DNA glycosylase to generate an abasic site, which is subsequently detected by the ASB methodology. The ability to modify this technique for the detection of uracil has these advantages: small quantities of DNA are required (4 microg of DNA); the assay is adaptable to DNA from both cells and tissues; sensitivity is as good as that achieved by less accessible methodologies, like gas chromatography-mass spectroscopy (GC-MS); DNA strand breaks are not a confounding variable; preexisting aldehydic lesions are blocked through the use of methoxyamine; variation is very low (<3%); radioactive isotopes are not required; and the assay is easy to establish and involves only equipment and reagents that are inexpensive and readily available. This assay is conceivably adaptable to the detection of other DNA base lesions through the use of a variety of DNA glycosylases.     

Polyamines modulate nitric oxide production and COX-2 gene expression in response to mechanical loading in human adipose tissue-derived mesenchymal stem cells

For bone tissue engineering, it is important that mesenchymal stem cells (MSCs) display a bone cell-like response to mechanical loading. We have shown earlier that this response includes increased nitric oxide (NO) production and cyclooxygenase-2 (COX-2) gene expression, both of which are intimately involved in mechanical adaptation of bone. COX-2 gene expression is likely regulated by polyamines, which are organic cations implicated in cell proliferation and differentiation. This has led to the hypothesis that polyamines may play a role in the response of adipose tissue-derived MSCs (AT-MSCs) to mechanical loading. The aim of this study was to investigate whether genes involved in polyamine metabolism are regulated by mechanical loading and to study whether polyamines modulate mechanical loading-induced NO production and COX-2 gene expression in human AT-MSCs. Human AT-MSCs displayed a bone cell-like response to mechanical loading applied by pulsating fluid flow (PFF), as demonstrated by increased NO production and increased gene expression of COX-2. Furthermore, PFF increased gene expression of spermidine/spermine N (1)-acetyltransferase, which is involved in polyamine catabolism, suggesting that mechanical loading modulates polyamine levels. Finally, the polyamine spermine was shown to inhibit both PFF-induced NO production and COX-2 gene expression, suggesting that polyamines modulate the response of human AT-MSCs to mechanical loading. In conclusion, this is the first study implicating polyamines in the response of human AT-MSCs to mechanical loading, creating opportunities for the use of polyamines in tissue engineering approaches targeting skeletal defects.     

The effect of glutamine on prevention of glucocorticoid-induced skeletal muscle atrophy is associated with myostatin suppression

Excess glucocorticoids (GCs) cause muscle atrophy. Glucocorticoid-induced muscle atrophy is associated with increased intramuscular myostatin expression. Myostatin is a negative regulator of skeletal muscle mass. Glutamine prevents GC-induced muscle atrophy. We hypothesized that glutamine effect on reversal of GC-induced muscle atrophy is mediated in part by suppression of myostatin. We administered daily to male Sprague-Dawley rats dexamethasone, dexamethasone plus glutamine, saline or saline plus glutamine, all pair-fed. Animals were killed on day 5. Body weight and weights of gastrocnemius muscles were measured. Myostatin expression was measured by Northern and Western blots, and was compared with glyceraldehyde-3-phosphate dehydrogenase. Myoblast C2C12 cells were exposed to dexamethasone, or dexamethasone and glutamine, and their myostatin messenger RNA and protein expression compared with glyceraldehyde-3-phosphate dehydrogenase. Myostatin promoter activity was measured by luciferase activity of transfected C2C12 cells, grown in medium including dexamethasone, or dexamethasone plus glutamine. Rats that received dexamethasone showed significant body and muscle weight loss accompanied by an increase in intramuscular myostatin expression, compared with their saline-treated controls. Pair-fed rats given dexamethasone plus glutamine had significantly less reduction in body and muscle weights and lower myostatin expression when compared with those treated with dexamethasone alone. In C2C12 myoblast cells, addition of glutamine to dexamethasone prevented the hyperexpression of myostatin induced by dexamethasone. Myostatin promoter activity increased in cells exposed to dexamethasone, but this increase was partially blocked by addition of the glutamine. Administration of glutamine partially prevents GC-induced myostatin expression and muscle atrophy, providing a potential mechanism for the prevention of muscle atrophy induced by glucocorticoids.     

The Results of Brown Syndrome Surgery with Superior Oblique Split Tendon Lengthening

Purpose: To report the surgical outcome of superior oblique tendon split lengthening for management of patients with severe type of congenital Brown syndrome. Brown syndrome is characterized by hypotropia in primary position and limitation of elevation in adduction more than ?4.

Materials and methods: Fourteen consecutive patients with severe congenital Brown syndrome underwent superior oblique split lengthening surgery (10?mm). The amount of hypotropia in primary gaze and the degree of elevation in adduction were compared before and after the surgery. Any surgical complications were also recorded.

Results: Surgery was performed on 15 eyes in 11 female and 3 male subjects. Mean postoperative follow-up time was 12.93?±?1.79 months (ranging from 10 to 16 months). Average hypotropia in primary gaze improved from 16.2?±?5.5 prism diopters (range: 10–25 prism diopters) preoperatively to 5.9?±?4.0 prism diopters (range: 0–18 prism diopters) postoperatively recorded at final follow-up examination (p?p?Conclusion: Superior oblique split lengthening has a significant effect on reducing primary gaze hypotropia and improving elevation in adduction. This technique should be considered for the treatment of patients with severe congenital Brown syndrome.     

Growth hormone to improve short bowel syndrome intestinal autonomy: a pediatric randomized open-label clinical trial

Background: The ability of growth hormone (GH) to promote the weaning‐off of parenteral nutrition (PN) in short bowel syndrome (SBS) is unclear. No randomized controlled study is available in children. This study was undertaken to determine if GH could enhance the weaning off of PN in PN‐dependent children with SBS. Methods: A prospective randomized open‐label multicenter study was performed in 14 patients (mean age, 9 ± 1.4 years) with SBS (average small bowel length, 33 cm) and long‐term PN dependency (8 years) on an unrestricted diet. A standardized PN decrease with and without GH (0.14 mg/kg/d) was conducted. The patients were randomized to either a GH group (4 months of GH) or a control (CTR) group (4 months without GH, followed by 4 months with GH). Blood tests and a nutrition assessment of enteral and parenteral intakes were performed. Groups were compared with the Wilcoxon test. Results: Treatment with GH did not improve the weaning off of PN (decrease in PN caloric intake of 32.5% ± 9.6% in the GH group vs 35.2% ± 8.7% in the CTR group, nonsignificant). In the CTR group, GH treatment induced an additional but not statistically significant decrease of 8.8% ± 12.4% in daily calories. Parenteral needs returned to near basal rates 6 months after GH discontinuation (GH: 77.6% ± 10.6% vs CTR: 73.2% ± 7.4%). Weight decreased slightly in both groups. No biological parameters varied significantly. Conclusions: GH did not improve the weaning off of PN in PN‐dependent children with SBS.     

Period dependent branching process and its applications in epidemiology

In this paper we introduce a new technical development of branching processes that can potentially model spread of epidemics by including various stages of infection. In fact, we present an epidemic model that the disease spreads from an individual to another one in such a way that the ability of individual u to infect a susceptible individual depends only on how long u has been infected. For analysis of this model, we introduce a new and special model of the Crump–Mode–Jagers branching processes in discrete time and obtain some of its fundamental properties.