Role of endothelium in the maintenance of low pulmonary vascular tone in normal children

BACKGROUND: Resting vascular tone is low in the normal pulmonary circulation, and experimental studies have suggested that this may be due to the continuous release of endothelium-derived nitric oxide (NO), a locally acting vasodilator. We have investigated whether NO contributes to the normal control of pulmonary vascular tone and resistance in children. METHODS AND RESULTS: We studied the hemodynamic effects of NG-monomethyl-L-arginine (L-NMMA), a specific inhibitor of NO synthesis, on the pulmonary circulation of six children 2 to 17 years old (mean, 9 years) with congenital heart disease but normal pulmonary blood flow, pressure, and resistance (all had isolated left heart obstructive lesions). The diameter of a segmental pulmonary artery and pulmonary blood flow velocity were measured by quantitative angiography and intra-arterial Doppler catheters. There was a consistent, dose-dependent fall in pulmonary blood flow velocity in response to three increasing doses of L-NMMA (compared with baseline, flow velocity fell to 75 +/- 7%, 62 +/- 8%, and 40 +/- 10%, P < .01). Flow velocity returned to control values with subsequent infusion of L-arginine, the substrate for NO. Thereafter, acetylcholine, an endothelium-dependent dilator, produced an increase in flow velocity (56 +/- 10% greater than baseline, P < .01). Arterial diameter was unchanged during L-NMMA and L-arginine infusions, indicating that the major effect of each agent is to alter vascular tone distal to the segmental pulmonary arteries. CONCLUSIONS: The dilator action of endothelium-derived NO contributes to the maintenance of low resting pulmonary tone in normal children. Impairment of NO production may contribute to the elevated pulmonary vascular resistance that complicates some cases of congenital heart disease.     

Localized benign pleural mesothelioma arising in a radiation field

We collected 7 Friedreich ataxia (FRDA) pedigrees from France. All cases but one family were homozygous for an unstable GAA trinucleotide expansion in the first intron of the frataxin gene. In this peculiar pedigree absence of the GAA expansion supports the notion of possible genetic heterogeneity of FRDA.     

Natural variation within the principal arginine-specific protease gene, prpR1, of Porphyromonas gingivalis

Patients who were treated for fractures of the limbs were assigned to 1 of 2 groups for the management of postoperative pain. In Group 1 (postoperative patient-controlled analgesia group), 46 patients were given postoperative continuous epidural anaesthesia in combination with narcotic analgesics and this was regulated by the patient using a device. The 46 patients in Group 2 (control group) received suppositories or intramuscular injections of narcotic analgesics on their request. Patients in Group 1 needed suppositories and intramuscular injection of narcotic analgesics less often than those in Group 2, and had more satisfactory pain relief according to the visual analogue scale for pain assessment made on the first, second and third postoperative day. The time spent by nurses for pain management in Group 1 was less than that in Group 2. It appears that this patient-controlled method, combined with postoperative continuous epidural anaesthesia, is a safe, effective and efficient method for the management of postoperative pain.     

Suppression of crack growth in hybrid fibre composites

A theoretical analysis based on the assumed form of the strain field surrounding a crack bridged by reinforcing elements has been used to examine the growth of a crack propagating transversely to the fibres in hybrid fibre composites. An intermingled carbon fibre/glass fibre polymer matrix system has been considered. Two situations have been investigated. In the first of these the effect of the addition of carbon fibres on the development of cracks resulting from the failure of the glass fibres by stress corrosion has been studied. The analysis indicates that crack growth can be severely inhibited by a 5% volume fraction of type III carbon fibres. The analysis has been used also to investigate the process by which strong high failing strain glass fibres inhibit the growth of cracks caused by the fracture of localized clusters of low failing strain carbon fibres. The predictions of this analysis agree with existing experimental data on glass fibre/carbon fibre hybrids.     

Opiates and medial hypothalamic knife cuts cause hyperphagia through different mechanisms.

In Exp I, male Sprague-Dawley rats were given bilateral parasagittal medial hypothalamic knife cuts (KCs) or a sham procedure and fed a high-fat diet. KC and sham-operated Ss were approximately equally sensitive to the suppressive effects of naloxone (0.1–20 mg/kg, subcutaneously [sc]) on food intake. Ketocyclazocine (0.1–20 mg/kg, sc) generally increased daytime food intake in sham-operated Ss; in contrast, the normal hyperphagia of KC Ss was in most cases either unchanged or decreased by ketocyclazocine. In Exp II, neither diet composition nor hypothalamic KCs significantly affected the feeding responses to naloxone or the stimulatory effects of butorphanol tartrate (0.1–20 mg/kg, sc). It was hypothesized that the differential effects of ketocyclazocine in KC and sham-operated Ss were a consequence of the sedative effects of the drug combined with the elevated baseline of the KC Ss. This hypothesis was supported by Exp III, which showed that ketocyclazocine also reduced nocturnal intake in unoperated Ss and that butorphanol increased intake. That feeding responses to naloxone and butorphanol were essentially unchanged by hypothalamic KCs suggests that the opioid feeding system is independent of the longitudinal feeding inhibitory pathway believed to be involved in KC-induced hyperphagia. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reconstructive spine surgery in pediatric patients with major loss in vital capacity

The effects of exogenenous monoaminergic neurotransmitters (norepinephrine, NE; epinephrine, E; dopamine, DA and 5-HT) and inhibin alpha N-terminal fragments P32 (1-32), P32-Tyr on P4 production by incubated rat CL cells were studied. The results demonstrated that: (1) alpha fragments caused significant inhibition on P4 production. (2) 0.1 mmol/L NE (or E) and 10 mumol/L DA produced a marked increase in both basal and hCG induced P4 production by CL cells (P < 0.001). The rank orders of potency of the catecholamines in stimulating P4 production were different, for basal P4 production, NE > E > DA; but for hCG induced P4 production, DA > E > NE, i.e. the order just reversed. Addition of P32-Tyr significantly neutrolized the stimulatory action of E, but only slightly increased the action of NE. (3) alpha receptor blocker phentolamine and beta receptor blocker propranolol were effective in decreasing basal and hCG-induced P4 production, the latter being more effective than the former. It was further shown that both blockers augmented the inhibitory effect of alpha-fragments on P4 production. (4) Unlike NE, E, and DA, 5-HT at 0.5 mumol/L exerted inhibitory effect on the basal and hCG-induced P4 production, but profoundly supressed the inhibitory effect of alpha-fragments on P4 production. The above results suggested: (1) Adrenergic, DA and 5-HT receptors are present in rat CL, where catecholamine might exert a stimulating effect on basal and hCG-induced P4 production via different pathways. (2) The inhibitory effect of P32, P32-Tyr on P4 production might be related to their inhibition by partial blocking alpha/beta receptors, which were antagnized by 5-HT. (3) The action of P32, P32-TYr on P4 production is brought on the participation of neurotransmitters NE, E, DA and 5-HT.