The superoxide anion may mediate short- but not long-term effects of ultraviolet radiation on melanogenesis

Abstract The present study was carried out to examine the role of reactive oxygen species in mediating the melanogenic effects of UVR. B16 mouse melanoma cells responded to a single dose of UVR by showing increases in their melanin content. Although there was a small increase in melanin at 48-72 hours, which was associated with a rise in tyrosinase activity at 48 h, the greatest change occurred at 3 h and this was not associated with an increase in tyrosinase activity. This short-term response, unlike the more delayed melanogenic response, was reduced by superoxide dismut-ase (SOD). Xanthine oxidase (XO), which generates the superoxide anion (O₂). also increased the melanin content of B16 melanoma cells with effects at 3 h and 48 h. As with UVR, the delayed response was accompanied by an increase in tyrosinase activity but no such association was evident at 3 h. In addition, the short-term effect, like that seen with UVR, was reduced with SOD and to a lesser extent with catalase. In contrast to the effects found with XO, glucose oxidase, which generates hydrogen peroxide, had no effect on the melanin content or tyrosinase activity of the B16 cells. These results confirm previous observations that UVR is able to act directly on cells to bring about delayed increases in melanogenesis. They further demonstrate that UVR also stimulates melanogenesis through a more rapid action that is not associated with an activation of tyrosinase. This effect could be mediated by the O₂ which, rather than activating tyrosinase, could act by serving as a substrate for the enzyme.     

Reliability of radiographic measurement of fracture angulation in children with femoral shaft fractures

INTRODUCTION: Clinical decisions are based on x-ray measures of radiographs. However, the reliability of assessing the angular measurement of fractured femurs in children is unknown. The purpose of this study was to determine the intra- and interrater reliability of an x-ray assessment of femoral shaft fracture angulation in children. METHODS: On 2 occasions, 3 raters evaluated 30 radiographs of children aged 4 to 10 years, 3 to 24 months after a femoral fracture. The radiographs were evaluated by an orthopedic surgeon, an orthopedic fellow and a research assistant, using a standardized methodology. Reliability was assessed with the intraclass correlation coefficient (ICC), an index of concordance that ranges from 01, where > 0.75 indicates excellent concordance. RESULTS: The ICC for the intrarater ranged from 0.75 to 0.97. The interrater reliability ICC for anterior or posterior angulation was 0.91 (95% confidence interval [CI] 0.840.95) and for varus or valgus angulation was 0.90 (95% CI 0.790.95). A change in measurement of more than 5 degrees exceeds the variation in measurement and, therefore, can be attributed to a true shift in fracture position. CONCLUSIONS: With specific standardized protocols, radiographic assessment of femoral fractures is reliable, irrespective of the examiner's level of experience.     

Whole-heart cine MRI using real-time respiratory self-gating.

Two-dimensional (2D) breath-hold cine MRI is used to assess cardiac anatomy and function. However, this technique requires cooperation from the patient, and in some cases the scan planning is complicated. Isotropic nonangulated three-dimensional (3D) cardiac MR can overcome some of these problems because it requires minimal planning and can be reformatted in any plane. However, current methods, even those that use undersampling techniques, involve breath-holding for periods that are too long for many patients. Free-breathing respiratory gating sequences represent a possible solution for realizing 3D cine imaging. A real-time respiratory self-gating technique for whole-heart cine MRI is presented. The technique enables assessment of cardiac anatomy and function with minimum planning or patient cooperation. Nonangulated isotropic 3D data were acquired from five healthy volunteers and then reformatted into 2D clinical views. The respiratory self-gating technique is shown to improve image quality in free-breathing scanning. In addition, ventricular volumetric data obtained using the 3D approach were comparable to those acquired with the conventional multislice 2D approach.     

Transmural and endocardial Purkinje activation in pigs before local myocardial activation after defibrillation shocks.

BACKGROUND: Earliest recorded postshock myocardial activations in pigs originate in the subepicardium of the apex and lateral free wall of the left ventricle (LV) 30-90 ms after the shock. OBJECTIVE: The purpose of this study was to determine whether the Purkinje system is a candidate for the source of postshock activations by performing endocardial and transmural postshock activation mapping. METHODS: In five pigs, 32 plunge needles with 12 electrodes (1-mm spacing) were inserted into the LV apex and lateral free wall. Up to 70 plunge needles with six electrodes (2-mm spacing) were spread throughout the remainder of the LV, while 9-12 plunge needles with four electrodes (2-mm spacing) were inserted into the right ventricle. A basket catheter with 32 bipolar recording sites was inserted into the LV. Defibrillation-threshold (DFT)-level shocks were delivered during 10 episodes of electrically induced ventricular fibrillation. Electrograms of postshock activation cycles were analyzed for Purkinje and myocardial activations. RESULTS: Purkinje activations were recorded before local myocardial activation in 9% of basket electrograms and in 15% of plunge needles during the first postshock activation cycle. Purkinje activations were identified during the first and subsequent several postshock activation cycles in at least one basket and one needle electrogram in 96% and 98% of defibrillation episodes, respectively. CONCLUSIONS: The Purkinje system is active during the early postshock activation cycles after DFT-level shocks. Further studies are required to determine whether activation initiates in the Purkinje system or whether it is activated by the myocardium or by Purkinje-myocardial junctional cells.     

Multifocal calcifying epithelial odontogenic tumor.

The calcifying epithelial odontogenic tumor (CEOT), or Pindborg tumor, is a rare and benign odontogenic neoplasm that affects the jaw. The most common manifestation of CEOT is a unifocal or localized lesion of the involved jaw, which may appear clinically as a hard tissue swelling and radiographically as a mixed radiolucent-radiopaque mass. In this article, we present a unique case of CEOT affecting multiple sites in the maxilla and mandible of a 51-year-old white man. Though biopsy samples from all involved sites revealed similar histopathologic features consistent with CEOT, the fact that there was a multifocal presentation is an unusual phenomenon for CEOT and has never been reported. Multifocal odontogenic lesions are not typical but have been observed in conditions associated with known genetic mutations. For example, multiple odontogenic keratocysts are the most common feature of the inherited condition known as nevoid basal cell carcinoma syndrome. This case, however, is the first one to demonstrate that there may be a multifocal variant of CEOT that has not been previously recognized.     

HIV Facial Lipoatrophy: Causes and Treatment Options

Background. Human immunodeficiency virus (HIV)-associated facial lipoatrophy is becoming epidemic and may seriously affect quality of life.
Objective. To review the possible causes and treatment options for HIV facial lipoatrophy.
Methods. This article is based on a review of the medical literature and the author's clinical experience in treating HIV facial lipoatrophy.
Conclusion. Although absorbable injectable fillers and implants are helpful in treating HIV facial lipoatrophy, they are limited by cost and the short duration of correction. Newer forms of longer-lasting fillers (poly-l-lactic acid [Sculptra]) and permanent injectable fillers (liquid injectable silicone) are proving useful for treatment of this condition.     

Cerebral sodium sensors in the sodium-deplete sheep

The sodium intake of sodium deplete sheep was studied during local, push-pull perfusion of different solutions within the third cerebral ventricle. Sheep were made sodium deplete by continuous loss of parotid saliva, and were allowed access to 0.6 M NaHCO₃ solution for 2 h daily. Local perfusion within the third cerebral ventricle was performed before and during the access to sodium solution. Four perfusion sites were used: anterior dorsal and ventral, and posterior dorsal and ventral. Perfusion of 200 mM Na-csf caused a decrease in sodium intake at each perfusion site. Perfusion of ouabain, 10⁻⁶M, caused a reduction in sodium intake only during perfusions within the anterior portion of the third ventricle. The results may indicate that specific neuronal elements sensitive to changes in intracellular sodium concentrations are located around the anterior portion of the third cerebral ventricle. These neurones, however, are not exclusive sites from where sodium intake of sodium deplete sheep can be influenced.     

Is There an Advantage to Repairing Infected Mitral Valves?

Background. The therapy for native mitral valve endocarditis is in evolution. Antibiotics have significantly improved survival rates, but patients with complications of endocarditis may require surgical treatment.

Methods. Between January 1985 and December 1995, 146 patients underwent surgical therapy (repair or replacement) for native mitral valve endocarditis. All patients had documented bacterial endocarditis. Univariate and multivariate analyses were performed to determine predictors of hospital death, long-term event-free survival, and probability of repair. Patients were evaluated in three groups: all patients, patients with acute endocarditis, and patients with chronic endocarditis.

Results. There were ten hospital deaths (6.8%). Patients undergoing repair had a lower hospital mortality rate (p = 0.008) then those having replacement. Event-free survival was improved after mitral valve repair in the overall group (p = 0.02) and in the group with healed (chronic) endocarditis (p = 0.05). Although the acute endocarditis group demonstrated an improved event-free survival rate after mitral valve repair versus replacement (74% versus 20% at 6 years), this did not reach statistical significance.

Conclusions. We conclude that mitral valve repair is preferable to mitral valve replacement when possible, in patients with complications of endocarditis, as repair results in a lower hospital mortality and an improved long-term survival.