Dynamic QT Interval Changes from Supine to Standing in Healthy Children

Background

QT-interval variations in response to exercise-induced increases in heart rate have been reported in children and adults in the diagnosis of long QT syndrome (LQTS). A quick standing challenge has been proposed as an alternative provocative test in adults, with no pediatric data yet available.

Cardiovascular abnormalities in Turner's syndrome: What prevention?

Cardiovascular complications in Turner's syndrome are the most common cause of excess early mortality, with a life expectancy that may be reduced by more than 10 years. Congenital cardiac abnormalities are described in approximately one third of patients. These abnormalities are mostly left heart obstructions, the most common of which are bicuspid aortic valve (16%) and coarctation of the aorta (11%). Dilatations of the ascending aorta are often described and may occur in isolation from any heart disease, suggesting a vasculopathy specific to the syndrome, probably predisposed to by extracardiac risk factors such as oestrogen deficiency, diabetes, dysplidaemia and overweight. The most feared complication is aortic dissection with around a 100 cases, described at average age of approximately 35-years-old. This is believed to complicate 2% of induced pregnancies. Hypertension (HBP) usually essential, affects up to 50% of patients with Turner's syndrome. This is an important risk factor for cardiovascular complications and justifies aggressive treatment. On the other hand, retrospective studies have not demonstrated adverse cardiological effects due to growth hormone treatments. Patients with Turner's syndrome merit regular cardiology follow-up from childhood onwards, particularly if they have treated heart disease. The merits of preventative treatments for aortic dilatation have not been demonstrated in Turner's syndrome and justify prospective trials.     

Carcinoma of maxillary antrum: the role of pre-operative irradiation

• 1 Nineteen patients with carcinoma of the maxillary antrum were treated sequentially with pre-operative irradiation and radical surgery.
• 1 Seven of 19 patients (37 percent) were free of disease for longer than three and one half years (one patient for two years).
• 1 Infrastructure tumors were more favorable than those involving the entire antrum. The control rate for infrastructure tumors was five of 11 patients (45 percent).
• 1 The most important cause of failure is the inability to destroy the tumor locally or early local recurrence.
• 1 Pre-operative irradiation at a dose level of 6,000 rads in five weeks or its equivalent is an important addition to the treatment of advanced antral cancer.

     

The effect on the bonding strength of orthodontic brackets of fluoride application after etching

Etching of the enamel surface in preparation for bonding orthodontic brackets is an essential part of the bonding procedure. In an attempt to alleviate concerns regarding the decalcified enamel, it has been suggested that a fluoride solution be applied to the etched surface before placing the bonding material. The purpose of this study is to test the tensile bonding strength of the composite to fluoride-treated enamel. Four groups of 10 teeth each were compared. Group I received a solution of 2% NaF in 0.1 M H3PO4 after etching; groups II and III received a solution of 4% NaF in 0.1 M H3PO4 after etching; and group IV served as the control--that is, no fluoride solution was applied to the enamel after etching. The orthodontic brackets were bonded to the teeth in the four groups with the same procedure. The 40 teeth were then placed in synthetic saliva. Groups I, II, and IV were debonded after 24 hours; group III was debonded after 7 days. The Instron Universal testing machine was used to determine the tensile bonding strength of the adhesive to the teeth. The basic statistics for the tensile strength were calculated and the analysis of variance, general linear models procedure, was used to determine whether significant differences were present among the groups. The findings indicate that the application of either 2% or 4% NaF in a 0.1 M H3PO4 solution does not significantly influence the tensile bonding strength of the adhesive material to the enamel surface.     

Uvulopalatopharyngoplasty for sleep apnea in mentally retarded obese 14-year-old: an anaesthetic challenge

Anaesthetic management of patients with obstructive sleep apnea for upper airway surgery has always been a challenging task. We report our anaesthetic approach for a young, mentally retarded obese patient with documented obstructive sleep apnea undergoing uvulopalatopharyngoplasty. The therapeutic intervention before, during and after operation is discussed.     

Angiotensin AT2 receptors directly stimulate renal nitric oxide in bradykinin B2-receptor-null mice

Both bradykinin B2 and angiotensin II type 2 (AT2) receptors are known to stimulate renal production of nitric oxide (NO). To evaluate the individual contributions of AT2 and B2 receptors to renal NO production, we monitored renal interstitial, stable NO metabolites and cGMP by a microdialysis technique in conscious, bradykinin B2-null and wild-type mice (n=8 in each group) during low sodium intake alone or with the angiotensin AT1 or AT2 receptor blockers, valsartan (0.5 microg/min) or PD123319 (0.15 microg/min), or both. During normal salt intake, renal interstitial fluid NO and cGMP levels in B2-null mice were not different from those of wild-type mice. Low sodium intake increased NO and cGMP in wild-type mice but not in B2-null mice. Valsartan increased NO and cGMP in both wild-type and B2-null mice but to a significantly greater degree in the wild-type than in B2-null mice. PD123319 decreased NO and cGMP in both wild-type and B2-null mice. Combined valsartan and PD123319 decreased NO and cGMP in both wild-type and B2-null mice, but there was no significant difference during combined treatment from their levels after administration of PD123319 alone. Our results indicate that during ingestion of a low-salt diet, production of NO is mediated mainly via the AT2-B2 receptor cascade. Blockade of the AT1 receptor enhances the production of NO via the AT2 receptor in both wild-type and B2-null mice. We conclude that NO can be produced by 2 alternative pathways: directly through the AT2 receptor or indirectly from AT2 receptor stimulation of bradykinin via the B2 receptor.     

Notation in econometrics: a proposal for a standard

This paper proposes a standard for notation in econometrics. It presents a fully integrated and internally consistent framework for notation and abbreviations, which is as close as possible to existing common practice. The symbols used are instantly recognizable and interpretable, thus minimizing ambiguity and enhancing reading efficiency. The standard is designed in a flexible manner, thus allowing for future extensions.