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Biomedical subjects

M R Pearson

Publications and source records attributed to M R Pearson.

At least 19 recordsLinked to original sources
PubMed2006

Precision branching ratio measurement for the superallowed beta+ emitter 62Ga and isospin-symmetry-breaking corrections in A>or=62 nuclei.

A high-precision branching ratio measurement for the superallowed beta+ decay of 62Ga was performed at the Isotope Separator and Accelerator radioactive ion beam facility. Nineteen gamma rays emitted following beta+ decay of 62Ga were identified, establishing the dominant superallowed branching ratio to be (99.861+/-0.011)%. Combined with recent half-life and Q-value measurements, this branching ratio yields a superallowed ft value of 3075.6+/-1.4 s for 62Ga decay. These results demonstrate the feasibility of high-precision superallowed branching ratio measurements in the A>or=62 mass region and provide the first stringent tests of the large isospin-symmetry-breaking effects predicted for these decays.

Journal Article↗
PubMed2006

Near-surface structural phase transition of SrTiO3 studied with zero-field beta-detected nuclear spin relaxation and resonance.

We demonstrate that zero-field beta-detected nuclear quadrupole resonance and spin relaxation of low energy (8)Li can be used as a sensitive local probe of structural phase transitions near a surface. We find that the transition near the surface of a SrTiO(3) single crystal occurs at T(c) approximately 150K, i.e., approximately 45K higher than T(c)bulk, and that the tetragonal domains formed below T(c) are randomly oriented.

Journal Article↗
PubMed2006

Nuclear charge radii of 9,11Li: the influence of halo neutrons.

The nuclear charge radius of 11Li has been determined for the first time by high-precision laser spectroscopy. On-line measurements at TRIUMF-ISAC yielded a 7Li-11Li isotope shift (IS) of 25 101.23(13) MHz for the Doppler-free [FORMULA: SEE TEXT]transition. IS accuracy for all other bound Li isotopes was also improved. Differences from calculated mass-based IS yield values for change in charge radius along the isotope chain. The charge radius decreases monotonically from 6Li to 9Li, and then increases from 2.217(35) to 2.467(37) fm for 11Li. This is compared to various models, and it is found that a combination of halo neutron correlation and intrinsic core excitation best reproduces the experimental results.

Journal Article↗
PubMed2005

Scalar interaction limits from the beta-nu correlation of trapped radioactive atoms.

We have set limits on contributions of scalar interactions to nuclear beta decay. A magneto-optical trap provides a localized source of atoms suspended in space, so the low-energy recoiling nuclei can freely escape and be detected in coincidence with the beta. This allows reconstruction of the neutrino momentum, and the measurement of the beta-nu correlation, in a more direct fashion than previously possible. The beta-nu correlation parameter of the 0(+)-->0(+) pure Fermi decay of (38)K(m) is a =0.9981+/-0.0030+0.0032 / -0.0037, consistent with the standard model prediction a =1.

Journal Article↗
PubMed1998

Prinzmetal's angina and emotions: A neglected psychosomatic entity.

Prinzmetal's angina, a form of angina precipitated by vasoconstriction or spasm, appears to be a somatic phenomenon, but there is evidence, from research and case reports, of a major psychological component. In this study, individuals with Prinzmetal's angina were interviewed to determine the nature of their interpersonal relationships and their intrapsychic state at the time of onset of their chest pain. In addition, short developmental histories were obtained. The authors found that onset of chest pain was related to experiencing intense affect, and multiple levels of interpersonal and intrapsychic conflict, with strong conscious and unconscious, emotional and ideational links to previous traumas.

Adult↗
PubMed1996

Outcomes of thoracic surgery in dogs and cats.

Records of 146 dogs and 41 cats that underwent thoracic surgery at The University of Sydney Veterinary Teaching Hospital were reviewed for age, sex, breed, disease, operation date, periods of pre- and post-operative hospitalisation, use of surgical drains and outcome. Animals were assigned to 16 disease categories, the most common being patent ductus arteriosus, traumatic diaphragmatic hernia and oesophageal foreign body in dogs and traumatic diaphragmatic hernia in cats. Differences were observed between disease categories in all the criteria examined. There were almost equal numbers of male (72) and female (74) dogs, the median (range) age was 2.0 (0.2 to 14.0) years, the median pre-operative stay was 1 (0 to 14) days, the median post-operative stay was 4 (0 to 28) days and the overall survival to discharge rate was 78%. There were 24 male and 15 female cats (sex not recorded in 2 cats). The median (range) age was 3 (0.1 to 12) years, pre-operative stay 1 (0 to 6) days, post-operative stay 5 (0 to 15) days and the overall survival to discharge rate was 85%. Causes of post-operative deaths among animals in the most common categories are recorded and discussed.

Age Factors↗
PubMed1996

Use of anti-inflammatory and analgesic drugs in dogs and cats.

Responses (486) were collared from a survey of 5054 Australian veterinarians on their use of anti-inflammatory and analgesic drugs in dogs and cats. Almost all respondents used glucocorticoids (usually prednisolone) to treat allergic, pruritic dermatoses in dogs, while two-thirds also gave fatty acid supplements and one-half used antihistamines. Almost 60% of respondents initially injected a glucocorticoid (frequently a long-acting preparation) when treating inflammatory skin diseases in dogs. More than 90% of respondents used glucocorticoids to treat immune-mediated haemolytic anaemia or thrombocytopenia, and about one-third also gave cytotoxic drugs. Administration of prednisolone on alternate days was generally favoured for long-term enteral steroid therapy. Phenylbutazone was the most preferred treatment for painful or inflammatory musculoskeletal disorders of dogs, but aspirin and pentosan polysulphate were also used widely. Regarding the use of analgesics drugs generally, both narcotic analgesics and non-steroidal anti-inflammatory drugs (NSAIDs) were used more widely in dogs than in cats, but alpha-2 agonists were used similarly in both species. The most commonly used narcotic analgesics were pethidine and buprenorphine in both species, while the NSAIDs used most often were flunixin and dipyrone in dogs and ketoprofen in cats. More than 80% of respondents generally used analgesic drugs with potentially painful surgical procedures, with doses given usually before anaesthetic recovery. Analgesic use rates varied with the condition, ranging from 94% for patients with acute severe trauma, through 60% for cruciate ligament repair and 29% for perineal herniorrahphy, to about 5% for ovariohysterectomy and dog castration. The three clinical signs most frequently nominated as indicators of pain in dogs and cats were (in descending order) vocalisation, response to handling or palpating the affected area, and mental depression. Other items mentioned frequently were behavioural changes and immobility (in both species), inappetence/anorexia in cats, and altered respiration in dogs.

Anemia, Hemolytic↗
PubMed1995

Ventricular septal defect repair in a small dog using cross-circulation.

A haemodynamically significant ventricular septal defect was diagnosed in a 3-month-old male Cavalier King Charles Spaniel. A median sternotomy was performed and the 6.5 kg dog placed on cardiopulmonary bypass using pump-assisted cross-circulation. A 10 mm diameter peri-membranous ventricular septal defect was closed using a continuous suture of 4-0 polypropylene, via a 2.5 cm incision in the right ventricular outflow tract. The duration of cardiopulmonary bypass was 90 minutes. Complications in the immediate postoperative period were mild and easily managed.

Animals↗
PubMed1994

Hyperkalaemia associated with prolonged insufflation of carbon dioxide into the peritoneal cavity.

We measured plasma potassium concentrations in five anaesthetized pigs over a 3.5 h period during which a carbon dioxide pneumoperitoneum was maintained. During this period the abdominal pressure was kept at 1.96 kPa and normocapnia was maintained by intermittent positive pressure ventilation. The potassium concentration was found to increase with time to a mean of 5.63 (SD 0.44) mmol litre-1. Consideration should be given to monitoring plasma potassium concentration in patients undergoing prolonged laparoscopic surgery.

Animals↗
PubMed1993

An experimental study of cross-circulation for cardiopulmonary bypass in dogs.

Cardiopulmonary bypass using cross-circulation was evaluated in dogs. In eight experiments a greyhound (the donor) was used to perfuse a small mongrel dog (the recipient). Recipients averaged 40 per cent of the donor's weight. Total cardiopulmonary bypass was successfully established in all eight experiments and maintained for 60 to 90 minutes. Haemodynamic values (mean arterial pressure, central venous pressure, cardiac output) and arterial blood gas tensions in the recipient and donor dogs remained at near-baseline levels for the duration of cardiopulmonary bypass. Seven of the eight recipient dogs were successfully weaned from cardiopulmonary bypass at the end of the procedure.

Animals↗
PubMed1993

Use of a modified open patch-graft technique and valvulectomy for correction of severe pulmonic stenosis in dogs: eight consecutive cases.

A modified open patch-graft technique was used to correct congenital pulmonic stenosis in 8 dogs. Pulmonary valve dysplasia was moderate to severe in all cases, based upon clinical and echocardiographic criteria, and 3 dogs were in right-sided congestive heart failure at the time of surgery. Seven of the 8 dogs survived the surgery. One surviving dog displayed cerebral cortical dysfunction, the remaining 6 had no detectable neurological sequelae. Right ventricular failure was alleviated in all 7 surviving dogs, but right ventricular dilatation persisted post-operatively. Pulmonary valvulectomy and open patch-grafting provides an effective means of alleviating signs of congestive heart failure caused by pulmonary valve dysplasia, even in the presence of severe infundibular hypertrophy and dynamic outflow obstruction.

Animals↗
PubMed1992

Total venous inflow occlusion in the normothermic dog: a study of haemodynamic, metabolic and neurological consequences.

The acute haemodynamic and metabolic repercussions of total venous inflow occlusion were evaluated in six normal dogs, each of which underwent two four minute occlusions and one eight minute occlusion at normothermia. A further three dogs underwent a single eight minute period of occlusion and were allowed to recover from anaesthesia. Total venous inflow occlusion was well tolerated by all animals. They remained in sinus rhythm at the completion of occlusion, and unassisted haemodynamic recovery occurred rapidly. Recovery was quicker after four minutes than after eight minutes. There was no clinically detectable neurological impairment in three dogs which were allowed to recover.

Animals↗
PubMed1992

A new technique for surgery of the caudal vena cava in dogs using partial venous inflow occlusion.

The haemodynamic and metabolic effects of caudal vena cava occlusion were evaluated in six normal anaesthetised dogs. Each animal underwent a single eight minute episode of caudal vena cava occlusion. The procedure was well tolerated by all the dogs. Systolic arterial pressure was reduced by 62 +/- 5 per cent and the heart rate increased by 11 +/- 3 per cent. There was rapid haemodynamic recovery after the release of occlusion, all cardiovascular parameters returning to normal spontaneously within five minutes. Caudal vena cava occlusion is therefore safe for periods of up to eight minutes in normal dogs. This technique allows repair of caudal vena caval lesions without necessitating systemic heparinisation and the use of cavoatrial conduits.

Animals↗
PubMed1990

Tissue perfusion in anaesthetised sheep.

1. Tissue perfusion was measured in seven sheep by the radioactive microsphere method. 2. The sheep were anaesthetised and ventilated to a near normal arterial carbon dioxide tension. 3. Cardiac output was measured utilizing the Fick principle as applied to thermodilution and at the end of the investigation the sheep were killed by an overdose of anaesthetic. 4. The results were compared with previously published values for conscious sheep and anaesthetised horses and found to be similar when known variations in body composition and physiology were considered.

Anesthesia, General↗
PubMed1989

Tissue blood content in anaesthetised sheep and horses.

The blood content of tissue in eight anaesthetized sheep and three anaesthetized horses was measured using chromium labelled autologous red blood cells. 2. Approximately half the total blood volume was found to be distributed within the body tissues and, with the exception of the spleen and fat, the distribution was similar in these two species.

Anesthesia, General↗