Left pulmonary artery stenosis after transcatheter occlusion of persistent arterial duct.
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Child↗
Biomedical subjects
N Wilson
Publications and source records attributed to N Wilson.
Effect of foot compression on the velocity and volume of blood flow in the deep veins.
The A-V Impulse System reduces the incidence of deep vein thrombosis by pneumatically compressing the venae comitantes of the lateral plantar artery, causing an increase in the velocity of blood in the proximal axial veins. Using a duplex scanner the effects of altering the pressure, pulse duration and frequency of foot compression on the velocity and volume of blood flow in the superficial femoral and popliteal veins were quantified. In 20 legs, foot compression of 50, 125 and 200 mmHg significantly increased the maximum venous blood flow by 9.0, 13.4 and 15.1 ml/s respectively (P < 0.001). Conversely, reducing the frequency of compression from 6 to 3 cycles per min significantly increased the rise in peak flow from 10.1 to 14.8 ml/s (P < 0.001). Changing the duration of compression from 1 to 3 s had no significant effect on peak flow. Increased blood flow is best achieved with high-pressure low-frequency foot compression. Increasing the duration of compression beyond 1 s has no effect on augmentation of flow in the deep veins.
Adult↗
Prolonged isoproterenol treatment alters immunoregulatory cell traffic and function in the rat.
The mechanisms by which the sympathetic nervous system modulates functional parameters of the immune system have not been fully defined. In vivo, acute and chronic beta 2-adrenergic stimulation have been shown to have dramatic but opposing effects on circulating lymphocyte number and subset distribution in humans. In vitro studies have suggested impairment of numerous lymphocyte effector functions in the presence of catecholamines. To better define the effects of short and long term beta-adrenergic stimulation on lymphocyte migration patterns between circulating and splenic pools, as well as function, we infused rats with either low or high doses of isoproterenol over various time intervals. Specifically, we determined the number and subset composition of peripheral blood and splenic lymphocytes in addition to assessing responsivity to the T cell mitogen concanavalin A and antibody production. As a measure of in vivo lymphocyte proliferation, we also monitored the effect of these infusions on the number of peripheral blood lymphocytes and splenocytes and the splenic weight. Isoproterenol led to dose-dependent, short-lived decrements in mitogen-induced lymphocyte proliferation with concomitant decreases in circulating and splenic lymphocyte number in a subset-specific manner. Analysis of the distribution of circulating and splenic subtypes with isoproterenol treatment suggests definite but limited influences on beta-adrenergic stimulation on immunoregulatory cell traffic. We conclude that beta-adrenergic stimulation in the rat model leads to a dose-dependent, transient effect on lymphocyte proliferation and migration patterns. The relative lack of functional beta-receptors on rat lymphocytes and the propensity for early sustained receptor desensitization on exposure to agonist may account for qualitative differences seen between rats and humans.
Animals↗
Relationship of the antihypertensive effect of vasopressin withdrawal to sodium excretion in the Doca-salt hypertensive rat.
Arterial pressure, sodium excretion, urine output, and plasma atrial natriuretic peptide (ANP) concentrations were measured before, during, and after a 3-h i.v. infusion of arginine-vasopressin (vasopressin; 20 ng/kg/min) in conscious Doca-salt hypertensive rats. Arterial pressure was 166 +/- 8 mm Hg before the infusion of vasopressin; in comparison, pressure was only 130 +/- 4 mm Hg 5 h after stopping the infusion. The fall in pressure after withdrawal of an equipressor dose of phenylephrine in hypertensive animals was much less. In sham normotensive rats, pressure did not fall below control levels after stopping either the vasopressin or phenylephrine infusion. Sodium excretion rates were higher during infusions of vasopressin than during phenylephrine infusions. However, the elevations observed during vasopressin were similar in the hypertensive (25.3 +/- 4.9 mumol/kg/min) and normotensive (22.9 +/- 2.7 mumol/kg/min) groups. Urinary output increased to a greater extent in the hypertensive rats during the infusions of both vasopressin and phenylephrine, but the increases were similar for the 2 pressor agents. Plasma levels of ANP were elevated during the infusions of vasopressin in the normotensive rats, but not in hypertensive rats. The results indicate that the fall in pressure associated with cessation of a pressor dose of vasopressin appears specific to the hypertensive state, and relatively specific to vasopressin. This withdrawal-induced antihypertensive phenomenon (WAP) does not appear to be due solely to the preceding natriuresis and diuresis during the infusion of vasopressin. However, because the hypertensive animal may be more sensitive to a given degree of sodium loss, the possibility that the natriuresis could play a contributing or permissive role cannot be excluded.
Animals↗
[Transcatheter obliteration of patent ductus arteriosus in young adults with the Rashkind occluder].
Fourteen young adult patients between 14 and 29 years of age underwent 15 procedures of transcatheter occlusion of patent ductus arteriosus. In all patients but one, the attempt to implant the device was successful (92%). In one patient the ductus was judged to be too large for occlusion and the patient was sent for surgery. In no patient did the device embolize. A total of 6/13 (46%) patients was discharged home with no residual shunt. Follow-up data (between 3 and 18 months) are available in 10/13 patients. To date, 9/13 (70%) had total occlusion of their duct, in one patient after reocclusion.
Adolescent↗
Should general practitioners have access to paediatric cardiologists?
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Cardiology Service, Hospital↗
Fetal echocardiography.
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Echocardiography↗
Intron requirement for expression of the human purine nucleoside phosphorylase gene.
Abbreviated purine nucleoside phosphorylase (PNP) genes were engineered to determine the effect of introns on human PNP gene expression. PNP minigenes containing the first intron (complete or shortened from 2.9 kb down to 855 bp), the first two introns or all five PNP introns resulted in substantial human PNP isozyme expression after transient transfection of murine NIH 3T3 cells. Low level human PNP activity was observed after transfection with a PNP minigene containing the last three introns. An intronless PNP minigene construct containing the PNP cDNA fused to genomic flanking sequences resulted in undetectable human PNP activity. Heterogeneous, stable NIH 3T3 transfectants of intron-containing PNP minigenes (verified by Southern analysis), expressed high levels of PNP activity and contained appropriately processed 1.7 kb message visualized by northern analysis. Stable transfectants of the intronless PNP minigene (40-45 copies per haploid genome) contained no detectable human PNP isozyme or mRNA. Insertion of the 855 bp shortened intron 1 sequence in either orientation upstream or downstream of a chimeric PNP promoter-bacterial chloramphenicol acetyltransferase (CAT) gene resulted in a several-fold increase in CAT expression in comparison with the parental PNP-CAT construct. We conclude that human PNP gene expression at the mRNA and protein level is dependent on the presence of intronic sequences and that the level of PNP expression varies directly with the number of introns included. The disproportionately greatest effect of intron 1 can be explained by the presence of an enhancer-like element retained in the shortened 855 bp intron 1 sequence.
3T3 Cells↗
Communicable disease in New Zealand.
Communicable diseases remain a major problem in New Zealand; one which often only comes to the attention of management when an outbreak occurs and health care dollars are required for disease control. Hepatitis B and rheumatic fever remain the two diseases that place New Zealand in the developing nation league. Overall, the impact on mortality is low (only 5% in the 1-14 year age group) as is the impact on potential years of life lost. Morbidity figures are not known with any degree of accuracy as they are dependent on a notification system acknowledged to be deficient and hospital discharge data which include only a fraction of cases for a few serious diseases. The main preventive action hinges on the childhood immunisation programme which has undergone recent change. The true impact of environmental hygiene measures, health promotion and education has not been evaluated.
Adolescent↗
Cor triatriatum associated with total anomalous pulmonary venous drainage in the setting of mitral atresia and a restrictive interatrial communication.
A rare variant of cor triatriatum is described in which the proximal "accessory" chamber received all four pulmonary veins and drained into the levoatriocardinal vein and then into the innominate vein. The distal "true" chamber contained the left atrial appendage. The left atrioventricular valve was atretic and the interatrial septum was restrictive.
Angiography↗
Balloon coarctation angioplasty in adolescents and adults: early and intermediate results.
Twenty-three adolescent and adult patients with native coarctation of the aorta underwent balloon dilatation. Dissection of the aorta developed in one patient. Data were collected on the remaining 22 patients. They ranged in age from 15 to 55 years (mean 23 +/- 9.2 years). Invasive measurement of the peak systolic gradient (PSG) and biplane angiography were performed before and immediately after angioplasty and at follow-up 4 to 48 months (mean 15 months) later. PSG before dilatation was 37 to 100 mm Hg (mean 66.9 +/- 19.9 mm Hg) and decreased to 0 to 30 mm Hg (mean 9.1 +/- 11 mm Hg) immediately after dilatation (p less than 0.001). Restenosis occurred in two patients 6 months after dilatation, and one patient had an incomplete dilatation. These three patients underwent successful redilatation and remained improved 12 to 19 months later. There was no significant change in gradient at repeat catheterization in the remaining 20 patients. PSG was 0 to 20 mm Hg (mean 5.8 +/- 7.2 mm Hg). Angiography showed that a small aneurysm developed in one patient immediately after dilatation and in another 6 months later. Eleven patients were restudied more than once, and no change in gradient or size of the aneurysm was noted at mean follow-up 25 months after dilatation. This study demonstrated that balloon angioplasty is an effective method of treating adolescent and adult patient with native coarctation of the aorta. However, because of the uncertain natural history of aneurysm after dilatation, this procedure should be considered investigational until much longer follow-up times are available.
Adolescent↗
Total correction of transposition of great arteries with atrioventricular septal defect.
A successful anatomical correction of transposition of the great arteries with an atrioventricular septal defect is reported. This combination of anomalies is rare, and the anatomical correction is unusual in that the operation involves all four heart valves.
Child↗
Successful transcatheter closure of patent arterial duct six years after balloon dilatation of coarctation of the aorta.
A boy underwent total transcatheter occlusion of a patent arterial duct six years after successful balloon angioplasty of a native coarctation of the aorta. After successful implantation of a 12 mm device in the patent arterial duct there was no gradient across the descending aorta and five hours later there was no residual leak across the occluded patent arterial duct as judged by color Doppler.
Angioplasty, Balloon, Coronary↗
Left internal thoracic artery bypass graft in arterial switch with coronary transfer for transposition of the great arteries.
The left internal thoracic artery was anastomosed to the circumflex coronary artery to treat myocardial ischemia during an arterial switch procedure for transposition of the great arteries in a 6-month-old infant. Follow-up angiography revealed complete patency of the anastomosis.
Anastomosis, Surgical↗
Radioimmunoassay measurement of albumin in urine is a valid method for monitoring analbuminemia in rats.
Plasma and urinary albumin levels, urinary creatinine and urine volumes were measured at two-week intervals in Nagase analbuminemic rats (NAR) of either sex at ages from 42 to 154 days. Age matched Sprague Dawley (SD) rats were used as controls. Plasma concentrations of immunoreactive albumin (iALB) in NAR ranged from 0.007 +/- 0.002 to 0.023 +/- 0.003 mg/ml, and were lower in younger rats. In SD rats, plasma iALB concentrations ranged from 18.9 +/- 1.0 to 46.2 +/- 6.4 mg/ml. Urinary iALB output in NAR was less than 0.05 micrograms/mg creatinine measured over a 24 hr period, whereas it was greater than 20 micrograms/mg creatinine in the SD rats. Measurement of urine iALB concentrations in the NAR colony appears to be a reliable and a non-invasive method for monitoring the persistence of hypoalbuminemia.
Age Factors↗
Ectoparasitic mites (Acari) of sympatric Brazilian free-tailed bats and big brown bats in Alabama.
Seven species of mites were recovered from 133 Brazilian free-tailed bats, Tadarida brasiliensis, and 94 big brown bats, Eptesicus fuscus, from February through November 1990 in colonies that shared roosting space in east-central Alabama. The macronyssid Chiroptonyssus robustipes (Ewing) was the most common mite on T. brasiliensis (964 mites, 87% of bats infested) and on E. fuscus (109 mites, 29% of bats infested). However, C. rubustipes normally is a specific parasite of T. brasiliensis. The macronyssids Steatonyssus ceratognathus (Ewing) and S. occidentalis (Ewing) were recovered from both species of bats in low numbers. S. ceratognathus is not a typical parasite of either species of bat, but S. occidentalis normally is specific to E. fuscus. Predictably, S. occidentalis was most frequently collected from E. fuscus (16 mites, 9% of bats infested), but two specimens were recovered from T. brasiliensis. Five specimens of the laelapid Androlaelaps casalis (Berlese) (a mite that is frequently associated with rodents) and one specimen of the myobiid mite Ewingana (Doreyana) longa (Ewing) (a specific ectoparasite of T. brasiliensis) were also recovered from T. brasiliensis. Singletons of the rosensteiniids Mydopholeus sp. and Nycteriglyphites pennsylvanicus Fain, Lukoschus & Whitaker were the only additional mites collected from E. fuscus; both of these mites have previously been collected from bats or their guano but are recorded here from Alabama for the first time. With respect to ectoparasite cross-infestations, E. fuscus appears to be at greater risk from sharing roots with T. brasiliensis. This is highlighted by the comparatively large numbers of C. robustipes that occurred on E. fuscus and the low numbers of S. occidentalis on T. brasiliensis. Although mites were the only arthropods recovered from bats in this study, a separate survey in 1991 revealed that the bat bug Cimex adjunctus Barber infested some other colonies of T. brasiliensis and E. fuscus in Alabama.
Alabama↗
Transoesophageal echocardiography in neonates, infants and children: applicability and diagnostic value in everyday practice of a cardiothoracic unit.
OBJECTIVE: To determine the applicability of and information obtained by transoesophageal echocardiography in neonates, infants, and children in every day practice of a cardiothoracic unit. DESIGN: Four month prospective study. SETTING: Supraregional centre for paediatric cardiothoracic services. PATIENTS AND METHODS: 58 patients aged between four days and 16 years with a wide range of cardiovascular disease underwent transoesophageal echocardiography under sedation or general anaesthetic. One of two paediatric probes (6 or 7 mm diameter), or an adult probe (13 mm in diameter) was used. Whenever possible the investigation was immediately preceded by precordial echocardiography. MAIN OUTCOME MEASURES: Success, failure, technical difficulties, and complications of probe introduction and, when possible, comparison of the information obtained with that obtained from precordial echocardiography. RESULTS: Introduction of the probe was successful in 57 of the 58 patients. The only complication encountered was transient bradycardia during manipulation of the probe in a 2.2 kg baby. The adult (13 mm) probe was successfully used in children as small as 7.0 kg. Below this weight a smaller paediatric probe was required. In 56% of cases transoesophageal ultrasound provided information not obtained from the precordial approach. The technique was of particular value perioperatively and in the immediate postoperative period in neonates and infants and in the presence of valve prostheses and the investigation of mediastinal tumours in older children. CONCLUSIONS: Transoesophageal echocardiography is a valuable additional investigative tool for children of all ages. It is of particular value when acquisition of precordial image is impaired around the time of and after operation and in children with prosthetic valves or mediastinal tumour. Image quality was superior with the adult probe and we recommend the use of this probe unless the patient's weight is below 7 kg, when a paediatric probe allows this technique to be used usefully and safely in babies as small as 2.2 kg.
Adolescent↗