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Biomedical subjects

J W Balfe

Publications and source records attributed to J W Balfe.

At least 19 recordsLinked to original sources
PubMed2000

Ultrasound biomicroscopy of the eye in cystinosis.

OBJECTIVE: To describe the ocular ultrasound biomicroscopy (UBM) findings in patients with cystinosis. METHODS: Six patients with infantile nephropathic cystinosis, aged 16 to 25 years, and 6 controls (matched for age and spherical refractive error) were examined clinically and with UBM. Scleral reflectivity, corneal and iris thickness, central anterior chamber depth, angle width, trabecular meshwork to ciliary process distance, and ciliary sulcus width were measured. RESULTS: No patient had glaucoma or posterior synechiae, but all had crystals in the trabecular meshwork apparent with gonioscopy. Using UBM, the cornea and iris appeared similar in both groups, but the scleral reflectivity was increased in patients (P =.003). The angle was narrower in patients (mean +/- SD, 20 degrees +/- 7 degrees ) than controls (31 degrees +/- 5 degrees, P<. 001). The anterior chamber was shallower in patients (2556 +/- 197 microm) than controls (2968 +/- 284 microm, P<.001). The ciliary sulcus was closed or narrow in all patients (83 +/- 112 microm) compared with controls (339 +/- 135 microm, P<.001), with a reduction in the trabecular meshwork to ciliary process distance. CONCLUSIONS: This report of ocular UBM findings in cystinosis demonstrated narrowing of the angle and a ciliary body configuration similar to that reported for plateau iris syndrome. Gonioscopy demonstrated crystals in the trabecular meshwork. These findings may explain the predisposition of these patients to glaucoma.

Adolescent↗
PubMed2000

Ambulatory blood pressure monitoring in children: a large center's experience.

Ambulatory blood pressure monitoring (ABPM) is well established in adults and is becoming common in children. We reviewed 190 ABPM studies retrospectively (since 1990) to assess the failure rate, and analyzed the data from 97 patients 5-19 years old (1992-1996) to review the experience gained from the use of this technique in children and adolescents. Seventeen percent (32/190) of studies failed. Most children accepted ABPM, provided it was clearly explained in advance. There were differences between day and night readings of systolic blood pressure (BP), diastolic BP, and heart rate. BP did not correlate with height or weight. "White coat" effect apparently exists in children: clinic systolic BPs were higher than daytime systolic ABPM (no difference in diastolic). Eighty-nine percent (86/97) had an elevated BP load (>30% of readings >95th percentile). The antihypertensive medications of 16% (16/97) of patients were changed after ABPM. The nocturnal fall in BP (expressed as a percentage of the individual mean daytime values) was approximately normally distributed and was independent of age and height. Nocturnal systolic and diastolic dipping were closely correlated. Attenuation of nighttime dipping was observed in children with kidney disease and those with organ transplants. There is a need for normative data for ABPM for North American children. In our study, the technique was useful in selected cases, such as borderline or secondary hypertension, and for therapeutic monitoring when BP control is difficult.

Adolescent↗
PubMed2000

Nosocomial transmission of tuberculosis (TB) associated with care of an infant with peritoneal TB.

Nosocomial transmission of tuberculosis (TB) after exposure to infected peritoneal fluid has not been described. We report the exposure of 111 healthcare workers to infected dialysate from an infant with TB peritonitis. Two (5%) of 39 primary-care nurses, but no doctors or environmental service workers, had apparent tuberculin skin test conversions, raising the concern that patients with peritoneal TB may be a source for nosocomial transmission of TB.

Cross Infection↗
PubMed1999

Complications of gastrostomy feeding in children receiving peritoneal dialysis.

Gastrostomy tube (g-tube) feeding is recognized to improve the nutritional delivery to children with end-stage renal disease. A retrospective study was undertaken assessing the complications of g-tube feeding in children receiving peritoneal dialysis (PD). Twenty-three patients, mean age 3.8+/-3.2 years received PD and g-tube feeding for 758 patient-months, with 127 patients receiving PD for 1,969 patient-months used as controls. Peritonitis occurred every 18.4 patient-months in controls and 7.8 patient-months in those with a g-tube. Peritonitis occurred every 6.0 patient-months before and 8.1 patient-months after g-tube insertion in those undergoing g-tube insertion on PD. PD catheter exit site infection (PDESI) occurred every 18.7 patient-months in controls and 16.8 patient-months in those with a g-tube. PDESI occurred every 126 patient-months before and 16.2 patient-months following g-tube insertion. PD catheter replacement secondary to infection occurred every 109.4 patient-months in controls and 39.9 patient-months in those with a g-tube. It did not occur before g-tube insertion and occurred every 32.5 patient-months following insertion. Thirty-four episodes of g-tube exit site infection occurred, in 10 the same organism caused concurrent peritonitis. G-tube replacement occurred on 37 occasions. Hemodynamically significant gastrointestinal bleeding occurred in 3 patients, being terminal in 1. We conclude that, although not without risk, g-tube feeding in patients receiving PD is not contraindicated.

Bacterial Infections↗
PubMed1998

Non-steroidal anti-inflammatory drug-associated nephrotoxicity in Bartter syndrome.

We have followed four patients with Bartter syndrome for a mean of 25.4 years (range 21.5-28.8 years) after diagnosis. All patients received non-steroidal anti-inflammatory drugs (NSAID). In all patients, various degrees of renal dysfunction were noted to be temporally associated with NSAID therapy. In two patients, renal dysfunction resolved after discontinuing NSAID therapy, while maintaining other chronic medications such as potassium-sparing diuretics. Renal dysfunction persisted after NSAID withdrawal in two patients. We report these cases as a warning that NSAID should be considered an important cause of either reversible or irreversible renal dysfunction in Bartter syndrome.

Adult↗
PubMed1998

Diagnosis and management of stenotic aorto-arteriopathy in childhood.

Stenotic aorto-arteriopathy is an uncommon vascular lesion characterized by segmental arterial stenoses. We reviewed the experience with several management algorithms to define the most effective management course. The clinical records of 14 pediatric patients with acquired SAA who presented over a 16-year period were reviewed. Most patients presented with a mid-thoracoabdominal coarctation and were diagnosed with Takayasu arteritis. Differentiating between Takayasu arteritis and fibromuscular dysplasia was difficult on clinical grounds or by angiography. Medical management of the end-organ disease and renovascular hypertension was only palliative. Selective percutaneous transluminal balloon angioplasty of the stenotic renal arteries had only transient benefits; renal autotransplantation had slightly better success. Dilation of stenosed aortic segments with balloon-expandable endovascular stents and subsequent renal autotransplantation proved useful. Distinguishing SAA resulting from fibromuscular dysplasia caused by Takayasu arteritis in the chronic vaso-occlusive phase may be unnecessary for effective treatment. Therapy should focus on interventions to minimize the end-organ damage caused by the vaso-occlusive manifestations of the disorders.

Adolescent↗
PubMed1998

Examination of genotype and phenotype relationships in 14 patients with apparent mineralocorticoid excess.

Apparent mineralocorticoid excess (AME) is a genetic disorder causing pre- and postnatal growth failure, juvenile hypertension, hypokalemic metabolic alkalosis, and hyporeninemic hypoaldosteronism due to a deficiency of 11 beta-hydroxysteroid dehydrogenase type 2 enzyme activity (11 beta HSD2). The 11 beta HSD2 enzyme is responsible for the conversion of cortisol to the inactive metabolite cortisone and therefore protects the mineralocorticoid receptors from cortisol intoxication. Several homozygous mutations are associated with this potentially fatal disease. We have examined the phenotype, biochemical features, and genotype of 14 patients with AME. All of the patients had characteristic signs of a severe 11 beta HSD2 defect. Birth weights were significantly lower than those of their unaffected sibs. The patients were short, underweight, and hypertensive for age. Variable damage of one or more organs (kidneys, retina, heart, and central nervous system) was found in all of the patients except one. The follow-up studies of end-organ damage after 2-13 yr of treatment in six patients demonstrated significant improvement in all patients. The urinary metabolites of cortisol demonstrated an abnormal ratio with predominance of cortisol metabolites, i.e. tetrahydrocortisol plus 5 alpha-tetrahydrocortisol/tetrahydrocortisone was 6.7-33, whereas the normal ratio is 1.0. Infusion of [11-3H]cortisol resulted in little release of tritiated water, indicating the failure of the conversion of cortisol to cortisone. Thirteen mutations in the HSD11B2 gene have been previously published, and we report three new genetic mutations in two patients, one of whom was previously unreported. All of the patients had homozygous defects except one, who was a compound heterozygote. Our first case had one of the most severe mutations, resulting in the truncation of the enzyme 11 beta HSD2, and died at the age of 16 yr while receiving treatment. Three patients with identical homozygous mutations from different families had varying degrees of severity of clinical and biochemical features. Due to the small number of patients with identical mutations, it is difficult to correlate genotype with phenotype. In some cases, early and vigilant treatment of AME patients may prevent or improve the morbidity and mortality of end-organ damage such as renal or cardiovascular damage and retinopathy. The outcome of treatment in more patients may establish the efficacy of treatment.

Adolescent↗
PubMed1997

Brachydactyly-short stature-hypertension (Bilginturan) syndrome: report on two families.

We report on two families with autosomal dominant brachydactyly of hands and feet and hypertension. All affected members of the first family had proportionate short stature. However, the propositus and the affected relatives in the second family were only short compared to unaffected relatives. The hypertension was medically responsive in all cases. The propositus in the second family had poor compliance and a striking generalized vasculopathy. All patients were of normal intelligence and had a normal facial appearance. The brachydactyly-short stature-hypertension syndrome was first reported by Bilginturan et al. [1973] in a Turkish family and the families reported by us are Caucasian and Hispanic. The gene causing this condition in the original Turkish family was recently mapped to 12p. Our report expands our existing knowledge and the ethnic diversity of this syndrome.

Adult↗
PubMed1997

Pediatric pheochromocytoma. A 36-year review.

Fourteen children (10 boys and 4 girls, aged 8 to 17 years) had 20 pheochromocytomas treated over a 36-year period from 1959 to 1995 inclusive. Nine patients had 11 tumors before 1980; 5 children had 9 tumors up to 1987. There were no new children with pheochromocytomas at our hospital from 1988 to 1995. Hypertension, sweating, headache, and visual blurring were the most common symptoms and signs (average 5 months). The most reliable biochemical investigations were the urinary catecholamines and norepinephrine. Before 1980, intravenous pyelography and angiography were most successful in localizing the tumor, but since then ultrasonography and computerized tomography have been the radiological investigations of choice. Early involvement of the anesthesiologist in the preoperative control of the hypertension is essential; blood pressure (BP) control was achieved with phenoxybenzamine. The main anesthetic drugs used were: sodium thiopental, fentanyl, methoxyflurane, isoflurane, nitrous oxide, and metocurine. Sixteen tumors were adrenal and 4 were extra-adrenal (1 intrathoracic and 1 extradural). All except 2 tumors were completely resected; they ranged in size from 1.3 to 14 cm. Ligation of the tumor's venous drainage was usually associated with a sudden, temporary fall in systemic BP. There were 2 children with malignant tumors. Four patients had five recurrences (second pheochromocytoma) within 6 years, and all were heralded by a return of their original symptoms and signs. One girl was left with no adrenal tissue. The only complication was in a boy with a large, partly-resected malignant right adrenal tumor who had a subphrenic abscess drained and was left with a temporary bile fistula, cirrhosis, and chronic pain. All children were normotensive when discharged from hospital and remain alive and well with a follow-up of 7 to 36 years. There were no deaths. Long-term follow-up is essential. Key word Pheochromocytoma

Adolescent↗
PubMed1997

Renal tubular acidosis and osteopetrosis with carbonic anhydrase II deficiency: pathogenesis of impaired acidification.

Renal tubular acidosis with osteopetrosis is an autosomal recessive disorder due to deficiency of carbonic anhydrase II (CAII). A 3.5-year-old Egyptian boy with osteopetrosis and cerebral calcification has a persistent normal anion gap type of metabolic acidosis (plasma pH 7.26) and a mild degree of hypokalemia. A baseline urine pH was 7.0; ammonium (NH4+) excretion was low at 11 mumol/min per 1.73 m2; fractional excretion of bicarbonate HCO3 (FEHCO3) was high at 9% when plasma HCO3 was 20 mmol/l; citrate excretion rate was high for the degree of acidosis at 0.35 mmol/mmol creatinine. Intravenous administration of sodium bicarbonate led to a urine pH of 7.6, a FEHCO3 of 14%, a urine-blood PCO2 difference of 7 mmHg, NH4+ excretion fell to close to nil, and citrate excretion remained at 0.38 mmol/mmol creatinine. Intravenous administration of arginine hydrochloride caused the urine pH to fall to 5.8, the FEHCO3 to fall to 0, the NH4+ excretion rate to rise to 43 mumol/min per 1.73 m2, and citrate excretion to fall to < 0.01 mmol/mmol creatinine. These results show that our patient had a low rate of NH4+ excretion, a low urine minus blood PCO2 difference in alkaline urine, and a low urinary citrate excretion, but only when he was severely acidotic. He failed to achieve a maximally low urine pH. These findings indicate that his renal acidification mechanisms were impaired in both the proximal and distal tubule, the result of his CAII deficiency.

Acidosis, Renal Tubular↗
PubMed1997

A new classification for renal defects in net acid excretion.

The traditional classification of the group of disorders called renal tubular acidosis (RTA) into proximal and distal subclasses is based on which nephron segment is thought to have an abnormal function. Nevertheless, such a distinction may not be correct and also does not characterize the pathophysiology of the renal acidosis in each patient. In this article, we propose an alternative classification, one that is based on the component of net acid excretion that is abnormal. We also suggest expanding the definition of net acid excretion to include a term that describes the renal handling of metabolizable organic anions because their loss in the urine represents the loss of "potential bicarbonate." Because a low rate of excretion of ammonium (NH4+) is present in patients with both distal and isolated proximal RTA, our initial clinical step in patients with hyperchloremic metabolic acidosis (HCMA) is to evaluate the rate of excretion of NH4+. The basis for a low rate of excretion of NH4+ is shown by examining the urine pH. If the urine pH is low, further studies are performed to determine why the availability of NH3 is low; if the urine pH is high, further investigations are initiated to examine if the defect in H+ secretion involves the proximal or the distal nephron. Conversely, if the rate of excretion of NH4+ is high in a patient with HCMA, a component of the degree of acidosis could be attributable to a high rate of excretion of metabolizable organic anions. Case examples are provided to illustrate the approach and its implications for future molecular studies.

Acidosis, Renal Tubular↗
PubMed1996

Midodrine efficacy and pharmacokinetics in a patient with recurrent intradialytic hypotension.

Recurrent intradialytic hypotension, a complication of hemodialysis, is a consequence of an inadequate compensatory response or a paradoxic response to ultrafiltration-induced volume reduction. We report the use of midodrine, an alpha agonist, in an 18-year-old man with Bardet-Biedl syndrome and recurrent intradialytic hypotension. The clinical features of the intradialytic hypotensive spells are consistent with a paradoxic withdrawal of sympathetic activity, although an underlying abnormality in autonomic dysfunction cannot be excluded. Midodrine significantly increased the intradialytic blood pressure and decreased the intradialytic hypotensive episodes requiring intervention. The pharmacokinetic characteristics of the prodrug midodrine and the active metabolite de-glymidodrine in this patient with end-stage renal disease approximate those reported for patients with normal renal function. However, the prolonged terminal half-life for the active metabolite, de-glymidodrine, warrants careful administration in patients with renal failure.

Adolescent↗
PubMed1996

The team approach to the management of children on chronic peritoneal dialysis.

The diagnosis of chronic renal failure has a profound and lasting impact on a child and family, with the potential for impairment of the child's physical, mental, and social development. To achieve an ideal outcome, the peritoneal dialysis (PD) team must focus on preparing the child and family to perform home dialysis, prescribe the dialysis regimen most compatible with the patient's lifestyle and clearance requirements, ensure optimal nutrition, and facilitate psychosocial adaptation to PD. Close follow-up is essential for early detection, prevention, and treatment of potential complications of dialysis. A multidisciplinary team approach encompassing nursing, medicine, nutrition, and social work best suits the needs of the child and family.

Child↗
PubMed1996

Effect of puberty on markers of glomerular hypertrophy and hypertension in IDDM.

Epidemiological data implicate puberty as a factor in the initiation of diabetic nephropathy. However, the mechanism remains unclear. We hypothesized that puberty would result in an increase in glomerular hypertrophy and hypertension; these two early concomitant events are seen as pivotal to the pathophysiology of diabetic nephropathy. We studied the effect of pubertal duration on three surrogate markers of glomerular hypertrophy/hypertension: kidney volume (KV), microalbuminuria (MA), and Na-Li countertransport (CT). We recruited 177 subjects (87 female and 90 male; aged 6.2-22.1 years) with IDDM of 5 to 10 years' duration (6.8 +/- 1.6 years) into three groups with different pubertal duration: prepubertal since IDDM diagnosis; prepubertal at diagnosis, now pubertal; or early puberty at diagnosis, now postpubertal. KV was measured by ultrasound and corrected for body surface area; MA was defined as urinary albumin excretion of 15-200 micrograms/min in two of three 24-h samples, and Na-Li CT was measured in erythrocytes. As pubertal duration increased, there was a disproportionate increase in mean KV (prepubertal, 247 +/- 6 [SE] ml/1.73 m2; pubertal, 282 +/- 7/1.73 m2; postpubertal, 295 +/- 7/1.73 m2, P = 0.001), prevalence of nephromegaly (KV > 300 ml/1.73 m2) (14, 31, and 45%, respectively, P = 0.001), and prevalence of MA (0, 9.7, and 20.5%, respectively, P = 0.003). Subjects with KV > 300 ml/1.73 m2 were eight times more likely to have MA than those with KV < 300 (odds ratio 8.1, 95% confidence interval 2.4-27.4, P = 0.0001). There was no effect of pubertal duration on Na-Li CT. Multiple regression with KV as the dependent variable found an association with pubertal duration, MA, Na-Li CT, and current HbA1c (P < 0.0001). Our findings indicate that pubertal duration is an important determinant of both KV and MA and suggest that nephromegaly precedes microalbuminuria. We postulate that these effects are attributable to the influence of the pubertal milieu on glomerular hypertrophy/hypertension.

Adolescent↗