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Biomedical subjects

G Nunn

Publications and source records attributed to G Nunn.

16 recordsLinked to original sources
PubMed1997

Combined coronary artery bypass grafting and carotid endarterectomy.

Combined carotid endarterectomy and coronary artery bypass grafting was performed in 52 patients between January 1982 and September 1994. Forty-nine patients had stable or unstable angina and three had symptom-free coronary artery disease detected by stress testing. Thirty-one patients had triple-vessel disease and 17 had left main trunk or left main equivalent coronary artery disease. Five patients had symptom-free carotid artery disease, 12 had non-specific neurological symptoms, and 35 had transient ischaemic attacks. Carotid endarterectomy was performed first, followed by coronary artery bypass grafting. There were three postoperative deaths, two cardiac and one neurological, for a mortality rate of 5.8%. One patient suffered a permanent neurological deficit (1.9%). It is concluded that combined carotid endarterectomy/coronary artery bypass grafting can be performed in selected patients with acceptable neurological morbidity, although cardiac mortality was not eliminated by the combined approach.

Angina Pectoris↗
PubMed1995

Spontaneous convulsions in Charles River Wistar rats.

Spontaneous clonic convulsions in the Charles River Wistar rat have been observed at an incidence of 1.5%. Females (2.3%) are more susceptible than males (0.7%). These convulsions are not seen in rats of less than approximately 16 weeks of age. Some animals have exhibited single convulsions whilst others have convulsed on numerous occasions. No histopathological abnormalities of the brain have been recorded for these animals following routine examination.

Aging↗
PubMed1993

Two-year carcinogenicity study of tamoxifen in Alderley Park Wistar-derived rats.

Tamoxifen, a nonsteroidal antiestrogen used widely in the treatment of breast cancer, was tested in a conventional 2-year carcinogenicity bioassay in rats, a species in which tamoxifen acts variably as a partial agonist and antagonist on different target tissues. Groups of 51 males and 52 females were given 5, 20, and 35 mg/kg of tamoxifen/day by gastric intubation in 0.5% hydroxypropyl methylcellulose at 5 ml/kg dose volume. There were 102 male and 104 female controls dosed with vehicle alone. Growth rate and food consumption were reduced in all treated groups. The major finding was a dose-related increase in the incidence of hepatocellular tumors which were first observed after 31 weeks of treatment in the top dose group. The majority of the neoplasms were hepatocellular carcinomas showing a well differentiated trabecular pattern. Some tumors were glandular in type. Mortality was increased in the 20 and 35 mg/kg dose groups compared with controls as a result of these tumors. By contrast, survival was greater than controls in rats given 5 mg/kg tamoxifen despite the presence of hepatocellular tumors due to a reduction in the number of pituitary tumors in females and less chronic renal disease in males. The mechanism of hepatic tumor induction by tamoxifen in rats is unclear. In view of the lack of genotoxic activity in conventional genotoxicity studies and lack of similar effect in mice or in humans, the findings may relate to a particular constellation of effects in rats. All other drug-induced changes in this study were nonneoplastic in nature and most appeared to be the result of hormonal perturbation since they were confined to endocrine organs or have been seen previously in rats treated for long periods with tamoxifen.

Animals↗
PubMed1992

Minimally invasive management of transposition of the great arteries in the newborn period.

This study reports on a predominantly noninvasive management program for neonatal transposition of the great arteries [TGA] incorporating balloon atrial septostomy [BAS] under echocardiographic control. BAS was performed in 25 consecutive patients presenting with TGA between April 1988 and April 1990. Structural and coronary anatomy was evaluated echocardiographically with angiographic supplementation only when additional data were required. This information was correlated, where possible, with direct anatomic findings and subsequent course. BAS was performed through the umbilicus in 17 patients (85% of patients in whom this approach was attempted). Thirteen patients did not require ventilation during BAS. There were minimal complications and satisfactory septostomies in all cases. Coronary anatomy was correctly predicted in all patients where anatomic correlation was available. Without invasive investigation 9 patients underwent neonatal arterial switch procedures and 2 underwent palliative procedures. BAS under echocardiographic control proved safe, effective, minimally traumatic and mostly possible via the umbilical vein. The umbilical vein, where patent, permitted rapid safe access for BAS. Echocardiographic diagnosis of the coronary artery, and structural and functional anatomy was reliable and allowed minimally invasive preoperative management in many patients.

Cardiac Catheterization↗
PubMed1991

What is the best method for assessing the long-term outcome of surgery for accessory pathways and atrioventricular junctional reentrant tachycardias?

The success of surgery for supraventricular tachycardia (SVT) is evaluated by a variety of methods in different hospitals. Unfortunately, the predictive values of these methods are not known. We therefore compared the various methods in 261 patients undergoing surgery for SVT at Westmead Hospital since 1981. Surgical outcome was assessed by early tests during the first week after surgery (serial 12-lead electrocardiograms, telemetric monitoring of the electrocardiogram, and electrophysiological study performed using epicardial wires); later tests at 6 months after surgery (12-lead electrocardiograms and electrophysiological study); and symptomatic review done by telephone interview at a median of 34 months after surgery. Early tests were obtained in 97%, later tests were obtained in 76%, and symptomatic review was obtained in 98% of patients. All of the examined tests were inaccurate methods of surgical assessment compared with the late electrophysiological study. A large proportion of the patients proven to be surgical failures at the late electrophysiological study were not detected by early tests (83%), by later electrocardiograms (66%), or by symptomatic assessment (41%). Accurate assessment of surgical outcome requires a late electrophysiological study to permit comparison of surgical techniques. Late electrophysiological study also provides accurate information on the current risks and benefits of proposed surgery for communication to patients to enable them to make an informed decision on future treatment. Most patients are willing to have a late electrophysiological study and usually benefit from clarification of their true surgical outcome.

Cardiac Pacing, Artificial↗
PubMed1987

A new laryngoscope. A modified laryngoscope to facilitate intubation in cases of restricted access.

This is a report of a modification to one design of laryngoscope to increase the angle between blade and handle, to facilitate intubation in cases of difficult access, such as in obstetric practice or in patients in whom neck flexion is limited, for example by skull traction. The modification offers the unique advantage of two useful blade angles in one instrument. The first type described would be suitable for use in small units where it is thought that a laryngoscope solely for use in rare cases of difficult access would not be justified. It would also be suitable for inclusion in resuscitation kits for use both within and outside hospital. The second type would be more suitable for the maternity or spinal injuries unit, or the difficult intubation box of a general operating theatre suite.

Equipment Design↗
PubMedDate not supplied

Primary intraventricular cardiac tumors in children: contemporary diagnostic and management options.

We reviewed the intraventricular cardiac tumors presenting at our institution between 1985-1991, studying the presentation, modes of investigation, and evidence of hemodynamic compromise. Thirteen patients presented with intraventricular tumors during the study period. Two of the tumors were rhabdomyosarcomas, one was a myxoma, and 10 were rhabdomyomas. All patients were evaluated with two-dimensional and pulsed Doppler echocardiography and B-color imaging was undertaken in three patients. Four patients presented for elective scans to complement investigations for tuberous sclerosis, seven patients had cardiac symptoms, and two patients presented prenatally. Obstruction to intracardiac flow was present in five patients. Two patients had the tumor excised and one had an open biopsy of the tumor. One patient had an transvascular biopsy at cardiac catheter. Early detection of cardiac tumors is increasing, particularly rhabdomyomas. With fetal echocardiography, more patients should come to attention prenatally. B-color may be useful addition in assessing cardiac tumors, aiding detection and definition of intramural lesions.

Child↗
PubMedDate not supplied

Branch pulmonary artery growth after blalock-taussig shunts in tetralogy of fallot and pulmonary atresia with ventricular septal defect: a retrospective, echocardiographic study.

We performed a retrospective echocardiographic study in tetralogy of Fallot (TOF) or pulmonay atresia with ventricular septal defect (PA&VSD) to evaluate the effects of Blalock-Taussig shunt on branch pulmonary artery growth. There were 35 patients with TOF and 11 with PA&VSD. We measured the right and left pulmonary artery area index and also the combined pulmonary artery area index, both before and after shunt operation. The mean +/- SD of these three variables before the shunt operation in the TOF group were 63.5 +/- 22.5, 57.8 +/- 24.9, and 121.4 +/- 42.8 mm(2)/m(2); after shunt operation they were 98.5 +/- 33.6, 85.9 +/- 31.9, and 184.0 +/- 59.8 mm(2)/m(2), respectively (p values <0.0001, <0.0002, and <0.0001, respectively). In the PA&VSD group the comparable values before shunt operation were 66.5 +/- 16.0, 55.4 +/- 10.6, and 120.9 +/- 26.9 mm(2)/m(2) and after shunt operation were 90.5 +/- 22.9, 77.2 +/- 24.1, and 166.6 +/- 44.4 mm(2)/m(2), respectively (p values <0.0006, <0.014, and <0. 002, respectively). We also examined the effect of distensibility of pulmonary arteries by comparing the percentage change in size of the combined pulmonary artery area index in the first 4 months after shunt with those after this time (p < 0.023). There were no significant differences between left- and right-sided shunts, origin and distal pulmonary artery growth, and the TOF and PA&VSD groups.

Echocardiography↗
PubMedDate not supplied

Urinary tract toxicity in rats following administration of beta 3-adrenoceptor agonists.

ZD7114, [(S)-4-[2-(2-hydroxy-3 phenoxypropylamine)ethoxy]-N-(2-methoxyethyl) phenoxyacetamide], and ZD2079, [(R)-N-(2-[4- (carboxymethyl)phenoxy]ethyl)-N-(beta-hydroxyphenethyl)ammonium chloride], are beta 3-adrenoceptor stimulants with selectivity for brown adipose tissue. ZD7144 is the hydrochloride salt of the S-enantiomer of the racemic amide ZD2079. They were developed as potential novel treatments for obesity and non-insulin-dependent diabetes mellitus. Male and female rats were dosed separately by gavage for a minimum of 28 days with 0, 10, 50, and 500 mg/kg/day of ZD7114 or with 0, 10, 30, and 150 mg/kg/day of ZD2079. Two further groups of male and female rats were dosed with 0 and 500 mg/kg/day of ZD7114 for 28 days and were then allowed a 6-wk, undosed withdrawal period. At high doses, both compounds caused urinary tract toxicity, which primarily affected the distal tubules and collecting ducts of the kidney via tubular necrosis. They also caused ureteric inflammation, cystitis, and accumulation of crystalline inclusions throughout the urinary tract. As a result of urinary tract toxicity, affected animals from one or both studies showed reduced red blood cell indices, lower platelet counts, and higher white cell counts. Blood chemistry revealed lower plasma concentrations of glucose (7.28 +/- 1.37 compared to 8.11 +/- 0.65 for the control) and total protein (63.42 +/- 3.65 compared to 69.17 +/- 3.24 for the control) and increased plasma urea (37.15 +/- 19.96 compared to 8.09 +/- 0.87 for the control). Urinalysis showed an increase in the number of crystals, blood, and protein. In the urinary tract, the severe crystalluria with accumulation of crystalline material indicated that this may have a role in the etiology of the target organ toxicity. Poor solubility of the compounds at normal urinary pH was considered a possible mechanism for the crystalluria.

Adrenergic beta-Agonists↗
PubMedDate not supplied

The surgical management of aortopulmonary window using the anterior sandwich patch closure technique.

Between 1969 and June, 1986, 13 patients with aortopulmonary window were evaluated and operated upon with eleven survivors. All were children with ages ranging from 2 weeks to 2 1/2 years and had a typical aortopulmonary window (Type 1) with a connection between the ascending aorta and main pulmonary artery. Six of them also had associated cardiac anomalies. Operative techniques included both closed and open procedures. Simple ligation was carried out in two, while the remaining 11 patients were operated upon with the aid of extracorporeal circulation. "Sandwich" patch closure was the preferred method which was employed in 7 patients.

Aortopulmonary Septal Defect↗
PubMedDate not supplied

Evaluation of synthetic and biosynthetic conduits used as aorto-pulmonary shunts in growing pigs.

Synthetic and biosynthetic conduits 6 mm in internal diameter and 3 cm long were implanted as aorto-pulmonary shunts in 4 week old piglets. The synthetic conduit was made of Polytetrafluoroethylene (P.T.F.E.) manufactured by Gore-Tex; the biosynthetic graft was prepared by tanning bovine ureters and covering it with a polyester mesh. Two groups of six animals for each conduit underwent operation. Following implantation, when the animals were physiologically stable, the pressure and blood flow were measured in the pulmonary artery, conduit and aorta, and at the same time blood gases were obtained. These measurements were repeated four weeks later, following which the grafts were excised and processed for histological studies. All the conduits were patent, 4 weeks after implantation, but whereas there was little difference in the flows through the bovine grafts (506 ml/min) there was a marked reduction in the flow through the Gore-Tex conduit (235 ml/min). These differences could be related to the changes seen histologically. No drugs were used to affect patency of the conduits in this study.

Animals↗