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Biomedical subjects

P Burrows

Publications and source records attributed to P Burrows.

At least 19 recordsLinked to original sources
PubMed2001

End-stage renal disease: factors affecting referral decisions by family physicians in Canada, the United States, and Britain.

The objective of this study is to determine how patient age, sex, creatinine level, and comorbidity affect referral decisions for the treatment of end-stage renal disease (ESRD) and whether these decisions are affected by physician characteristics in three countries: Canada, the United States, and Britain. A vignette-based questionnaire was mailed to a random sample of family physicians in Ontario, Canada (1,818 physicians); all family physicians in the state of New York (1,814 physicians); and a sample of general practitioners from the south of England (2,228 physicians) in 1996. Physicians were presented with clinical scenarios involving a patient with varying degrees of renal insufficiency and a complicating comorbidity, including angina, diabetes, cancer, mental illness, or socioeconomic circumstances. They were asked to indicate the likelihood of referral. Half the physicians received a questionnaire describing a male patient, and half, a female patient. Mean creatinine levels at which physicians would refer were 260 micromol/L for British physicians, 297 micromol/L for Canadian physicians, and 340 micromol/L for American physicians. No difference in referral rates was found based on the sex of the patient or physician. Sixty-five percent of American and Canadian physicians would refer regardless of patient age, but only 49% of British physicians would do so. Family physicians in the United States, Canada, and Britain function as gatekeepers for patients with ESRD. They are less likely to refer based on increasing severity of comorbid conditions. They also discriminate based on age, but not sex.

Adult↗
PubMed1999

Antenatal diagnosis of fetal hepatic hemangioma treated with maternal corticosteroids.

BACKGROUND: Infantile hepatic hemangioma is a benign liver tumor with potentially fatal complications. Response of these lesions to steroid therapy has been well documented in infants. Successful antenatal treatment of a fetal hepatic hemangioma with maternal corticosteroids is reported. CASE: A 36-year-old woman, gravida 2, para 1, had an ultrasound at 17 weeks which showed a fetal hepatic hemangioma. Because of increase of the tumor and enlarged fetal heart, maternal oral corticosteroid therapy was commenced at 28 weeks, which progressively decreased the mass. The infant was delivered at 36 weeks with no evidence of heart failure, and at 7 months the tumor was barely seen on ultrasound. CONCLUSION: When an enlarging fetal hepatic hemangioma is detected antenatally, maternal corticosteroid therapy should be considered.

Adult↗
PubMed1999

Simulated surgery.

Explore the source record for details and available documents.

Clinical Competence↗
PubMed1997

Quasielastic light scattering study of the living human lens as a function of age.

PURPOSE: To determine contributions of molecular scattering elements to the increase with age in the light scattered from the human ocular lens in vivo. METHODS: We used quasielastic light scattering to measure autocorrelation functions of the intensity of light scattered in vivo from three locations (anterior, nuclear and posterior) along the optic axis in ocular lenses of 225 subjects, ranging from 17 to 63 years of age. We deduced probability distributions of key parameters (Is, If, Ii, IT), which describe contributions of slowly diffusing (Is), rapidly diffusing (If) and relatively immobile (Ii) scattering elements to the total light intensity (IT) scattered into the collection optics. We deduced characteristic time tau s and tau f that describe the Brownian motion of scattering elements. RESULTS: Probability distributions for each age decile show clearly defined shifts in key parameters with age. IT at the nucleus increases by a factor of three from age 20 to 60 years. This increase is produced principally by an approximate five-fold increase is Is. IT and Is and can be detected with an accuracy of approximately +/- 10%. We estimate threshold values for IT, which mark the boundary beyond which clinical cataract becomes manifest. This boundary represents 6 to 8 times the light scattering efficiency expected from the newborn lens. CONCLUSIONS: This methodology permits a sensitive, quantitative, clinically useful representation of the pre-cataractous molecular changes associated with aging in the living human lens.

Adolescent↗
PubMed1996

Hepatic kinetics and magnetic resonance imaging of gadolinium-EOB-DTPA in dogs.

RATIONALE AND OBJECTIVES: To measure the hepatic uptake and biliary elimination kinetics of gadolinium (Gd)-EOB-DTPA in dogs. METHOD: Two groups of four beagles each were anesthetized and given an intravenous bolus of 25 mumol/kg or 250 mumol/kg of Gd-EOB-DTPA. Blood, hepatic bile, and urine were collected over 140 minutes, and liver samples were obtained immediately after the dogs were killed. Conventional T1-weighted spin echo sequences of the liver were performed on a 1.5-Tesla (T) magnetic resonance imager during sampling. A ninth beagle received a bolus of 25 mumol/kg followed 140 minutes later with a bolus of 250 mumol/kg of Gd-EOB-DTPA. Wedge liver biopsies were obtained for Gd estimation at various times after dosing, and Gd concentration was measured by inductively coupled plasma atomic emission spectroscopy. RESULTS: The plasma concentration of Gd-EOB-DTPA decreased in a biexponential manner with half-lives of approximately 4 minutes and 60 minutes for the distribution and elimination phase independent of the dose given. Gadolinium bile concentration reached peak values between 80 and 140 minutes: 6.3 +/- 1.6 mmol/L for the low dose (LD) and 11.6 +/- mmol/L for the high dose (HD). Bile Gd output was 62.0 +/- 8.8 (LD) and 78.3 +/- 30.2 (HD) nmol/minute-kg 50 to 80 minutes after injection. Gadolinium-EOB-DTPA was excreted by the biliary route to 24.8 +/- 2.6 (LD) and 3.6 +/- 1.2 (HD) percent of the dose within 140 minutes. Liver Gd concentration was 0.43 +/- 0.14 (LD) and 4.3 +/- 0.5 (HD) mmol/kg liver tissue at the conclusion of the studies. Calculated concentrations in the hepatocyte were 60 (LD) and 15 (HD) times higher than in plasma at 25 minutes after dosing. Whereas the low dose exhibited excellent contrast enhancement for the whole period, the high dose displayed a biphasic signal enhancement with a decreasing signal caused by the too-high hepatic gadolinium accumulation. CONCLUSIONS: Transport of the Gd-EOB-DTPA into the hepatocyte exceeded elimination from hepatocyte to bile. The high dose defined a biliary transport maximum for Gd-EOB-DTPA of 78.3 +/- 30.2 nmol/minute-kg. The liver accumulation results from fast transport into the hepatocyte and rate-limited slower transport from hepatocyte to bile. The accumulation occurs against a strong concentration gradient, suggesting energy-dependent active transport into the hepatocyte.

Animals↗
PubMed1995

Pial arteriovenous fistula in children as presenting manifestation of Rendu-Osler-Weber disease.

We present four cases of pial arteriovenous fistula (AVF) in children as the presenting manifestation of Rendu-Osler-Weber disease (ROW). The common clinical manifestations of ROW in adults, such as skin telangiectasia and mucosal haemorrhagic complications, seldom occur in children, since telangiectases develop with age. Pial AVF in ROW also conform to the usual age incidence and are therefore present in childhood. Of the four children in this series, three had multiple AVF. Two presented with central nervous system haemorrhage, one with seizures and the other with progressive neurological deficit. There were no clinical or angioarchitectural differences between the AVF associated with ROW and sporadic AVF. The diagnosis was based in all cases on the family history. Transarterial embolisation to obliterate the AVF was carried out in all patients. One patient had early rebleeding after partial embolisation of the AVF, with a fatal outcome. Three patients were cured and one asymptomatic in long-term follow up. No exhaustive search was conducted for multiorgan telangiectases, since there is no indication for treatment of asymptomatic telangiectasia in ROW. No pulmonary fistulae were found. ROW should be suspected in children with multiple pial AVF; they may be the only manifestation of the disease, since epistaxis and telangiectasia are unusual in early life.

Adolescent↗
PubMed1995

A cross-sectional study of catheter-related thrombosis in children receiving total parenteral nutrition at home.

We performed a cross-sectional evaluation of deep vein thrombosis (DVT) related to the use of central venous lines (CVLs) in all pediatric patients receiving home total parenteral nutrition at our institution (N = 12). All children (5 months to 17 years of age) were examined with bilateral upper limb venography. All CVLs were flushed daily with heparin (200 units). At the time of evaluation, 49 CVLs had been placed in the 12 children. Of the 39 CVLs removed, 27 (66%) were blocked; venograms had not been previously obtained except of one child. Eight children had clinical evidence of superficial collateral circulation in the upper portion of the chest and the upper extremities; five had intermittent symptoms of superior vena cava obstruction. On venography, 8 of the 12 children had extensive evidence of DVT; two were unilateral and six bilateral. Five children were treated with warfarin (0.12 to 0.28 mg/kg per day) to achieve an international normalized ratio of 1.4 to 1.8. Neither bleeding nor further CVL-related DVT has occurred. We conclude that the risk of CVL-related DVT in children requiring home total parenteral nutrition is high, and that venography should be performed early in the event of CVL blockage. A multicenter, controlled trial assessing optimal warfarin therapy in this patient population is indicated.

Adolescent↗
PubMed1994

Bronchial artery aneurysm in hyperimmunoglobulinemia E syndrome.

A 2-year-old girl presented with a large right middle lobe cavitating lesion, complicated by life-threatening hemoptysis secondary to hyperimmunoglobulinemia E (hyper IgE) syndrome (Job's syndrome). This proved to be a bronchial artery pseudoaneurysm which was successfully embolized.

Aneurysm↗
PubMed1994

Lymphopoiesis today.

Max Cooper has made research contributions that cover phylogenetic and ontogenic aspects of lymphopoiesis and immunodeficiency diseases, and has used molecular approaches to understand lymphocyte development and function. A large gathering of international colleagues met at a recent symposium to celebrate the occasion of his 60th birthday.

Animals↗
PubMed1994

A comparison of flushing solutions for liver procurement using an isolated perfused porcine model.

There is no agreement on the best technique of in situ flushing of livers prior to storage. In order to study this, porcine livers were stored in the University of Wisconsin (UW) solution for 18 h and then assessed using an isolated perfused porcine model. Livers flushed in situ with UW solution were compared to livers flushed with a non-preservation solution (Hartmann's solution). No statistically significant differences could be found in bile production (18.7 +/- 4.4 vs 17.9 +/- 3.8mL/1000 g per 2 h), aspartate amino-transferase (AST) levels in the perfusate after 2 h of isolated perfusion (687 +/- 101 vs 724 +/- 114 U/L), potassium levels in the perfusate after 2 h on the circuit (5.4 +/- 1.5 vs 5.5 +/- 2.3 mmol/L), weight gain (15.2 +/- 3.7 vs 17.1 +/- 4.0%) or platelet sequestration (41.6 +/- 11.7 vs 37.4 +/- 9.8%) between livers flushed with UW solution as opposed to those flushed with Hartmann's solution, respectively. Of overriding importance was the solution in which the liver was stored, reconfirming the superiority of UW solution over an extracellular solution for preservation. If extrapolated to the clinical situation, these findings would have substantial cost-saving implications.

Adenosine↗
PubMed1994

Heparin therapy in pediatric patients: a prospective cohort study.

Current guidelines for heparin therapy in pediatric patients have been extrapolated from trials in adult patients without rigorous evaluation of efficacy and safety. We prospectively monitored consecutive pediatric patients receiving systemic doses of heparin over 10 mo at one institution using a predetermined nomogram to monitor maintenance therapy. Sixty-five consecutive children; 38 males and 27 females, received systemic doses of heparin. Thirty children had deep venous thrombosis and/or pulmonary embolism; 11 had arterial thrombi, most frequently after diagnostic angiography; and the remaining 24 received heparin prophylactically, for congenital heart disease. Twenty-nine (45%) of the 65 patients were less than 1 y of age and 22 (34%) were 10 y or older. Congenital heart disease was the predominant diagnosis under 1 y and deep venous thrombosis in older children. After a bolus dose of 50 U/kg, 39% of children (n = 30) achieved a minimal level activated partial thromboplastin time (APTT). Sixty-eight percent of children achieved a minimal level APTT by 24 h and 81% by 48 h. For all 65 children, APTT values were within the therapeutic range 43% of the time. APTT values outside the therapeutic range were twice as likely to be low as high. The average amount of heparin required to maintain therapeutic APTT values for children was 22 U/kg/h: 28 U/kg/h for infants < 1 y and 20 U/kg/h for the rest. Bleeding was rare (2%) and mild. Documented recurrent thrombotic disease was more common (7%) with associated morbidity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Survival analysis of infants under age 18 months presenting with tetralogy of Fallot.

The trend to perform early primary repair of tetralogy of Fallot prompted us to review our experience in the current era with the traditional protocol consisting of palliation during infancy, if required, and repair after infancy. During a 10-year period, 270 infants with tetralogy of Fallot presented aged less than 18 months. Thirteen infants (4.8%) had major noncardiac lesions that precluded definitive care for their congenital heart disease. Twenty infants (7.4%) had major associated cardiac lesions (atrioventricular septal defect or absent pulmonary valve syndrome, or both). Survival in this group was poor, with only 58% +/- 12% reaching the age of 10 years. Four of the seven deaths occurred before intracardiac repair was performed. The remaining 237 infants presented with isolated tetralogy of Fallot. Eight-nine percent +/- 2.3% survived to age 10 years. Sixty percent of these infants required palliation, and survival in these infants did not differ from that in those who never required palliation. However, 19 infants (8%) required palliation in the first month of life. In these children, survival to age 10 years was significantly lower (77%), secondary palliation was frequently required (n = 11), and a transannular patch or conduit at the time of repair (10 of 14 patients) was more likely needed than it was in children who had not undergone a palliative procedure during the neonatal period. The survival in infants with tetralogy of Fallot is unlikely to be different, regardless of whether primary repair or a staged repair is carried out. The quality of survival, including the exercise capability and absence of arrhythmias, must be assessed to determine which protocol is superior.

Abnormalities, Multiple↗
PubMed1993

Nevus of Ota: treatment with high energy fluences of the Q-switched ruby laser.

BACKGROUND: The nevus of Ota is a benign dermal melanocytic lesion that has previously proved difficult to treat. Recently, the Q-switched ruby laser has been reported to be successful in treating benign pigmented lesions and tattoos. OBJECTIVE: Our study evaluates the treatment of 16 patients with nevus of Ota with the Q-switched ruby laser (694 nm). METHODS: Sixteen patients with nevus of Ota were treated with the Q-switched ruby laser with a pulse width of 28 nsec and energy fluences ranging from 7.5 to 10 J/cm2. Response to treatment was assessed by an independent investigator with photographs. RESULTS: The average number of treatments was 3.8 per patient. After two treatments, 44% of patients showed a 50% or greater improvement. After three treatments, 85% of patients showed a 50% or greater improvement; after four treatments, 100% of patients showed 50% or greater improvement. No patients had permanent textural changes or scarring. CONCLUSION: High-energy fluences of the Q-switched ruby laser lead to significant improvement without scarring of nevus of Ota after a few treatments.

Adolescent↗
PubMed1993

Hepatic kinetics and magnetic resonance imaging of gadolinium ethoxybenzyl diethylenetriaminepentacetic acid (Gd-EOB-DTPA) in dogs.

This complex study was designed to measure the transport and excretion characteristics of gadolinium ethoxybenzyl diethylenetriaminepentacetic acid (Gd-EOB-DTPA) in dog's livers following bolus and infusion. Simultaneous T1 magnetic resonance imaging was performed to measure maximum signal enhancement. Anaesthetized dogs had cannulation of the common bile duct and urinary bladder for collections and cannulation of the femoral artery and vein for monitoring, blood sampling and infusion. Gd-EOB-DTPA was administered by bolus (range 12.5-200 mumol/kg) and infusion (range 0.4-6.4 mumol/min per kg). An hepatic transport maximum 0.09-0.15 mumol/min/kg was achieved with a blood concentration of 0.03-0.06 mumol/mL. Marked hepatic affinity for Gd-EOB-DTPA was demonstrated with measurements of liver concentration. Maximum T1 signal enhancement was achieved with blood Gd-EOB-DTPA concentration of 0.02-0.03 mumol/mL and a liver concentration of 1-2 mumol/g. The transport maximum for Gd-EOB-DTPA in the dog was similar to that for ipodate and iodipamide and effective imaging was achieved with sub-maximal doses. The maximum signal enhancement at blood concentrations less than required for maximum transport suggest a wide latitude for effective clinical imaging.

Animals↗