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Biomedical subjects

R J Portman

Publications and source records attributed to R J Portman.

At least 37 records · Page 2Linked to original sources
PubMed1994

Changes in circadian rhythm of blood pressure in on-call pediatric residents.

To provide an objective measure of the effects of on-call stress on the blood pressure (BP) of a group of pediatric residents, we used a SpaceLabs Ambulatory Blood Pressure Monitor (ABPM) to compare 37 pediatric residents' on- and off-call BPs. Residents wore the ABPM for 24 h (once on call and again off call) to assess systolic and diastolic BPs every 30 min during the day and hourly overnight. We found significantly higher MESOR (an acronym for midline estimating statistic of rhythm, which yields a mean value more representative of the true mean than an average of a series of measurements) BPs and BP loads (%BP readings > 135 mm Hg for systolic and/or 85 mm Hg diastolic) during the on-call period. Some residents became hypertensive on call, and the normal 24-h pattern of lower nighttime blood pressures was altered during this period. ABPM monitoring may prove useful in evaluating the effectiveness of interventions to reduce the stress of residency training.

Blood Pressure↗
PubMed1992

Hypertension during reduction of long-term steroid therapy in young subjects with asthma.

Corticosteroids can induce hypertension, which reportedly remits as the drug is withdrawn. We studied nine patients with steroid-requiring asthma, aged 9 to 16 years, who had elevated blood pressures during corticosteroid treatment. Unlike in previous studies, all nine patients developed hypertension during corticosteroid reduction. Diastolic blood pressures were 50 to 84 mm Hg during maximum corticosteroid therapy (1 to 4 mg/kg/day); these values were in the normal range for seven of the nine patients and in the high normal range for the other two patients. Maximum diastolic pressures were 100 to 120 mm Hg, 1 to 8 weeks after corticosteroid reduction was started. Hypertension occurred at 0% to 70% of their maximum corticosteroid dose. Corticosteroid reduction was the only medication change. Renal causes of hypertension were excluded. Six patients had levels of renin and aldosterone measured before onset of treatment. All six patients had elevated levels of renin, and five patients had elevated levels of aldosterone. Blood pressure elevations were resistant to diuretic therapy but responded rapidly to angiotensin-converting enzyme inhibitors. Caretakers of subjects with asthma need to be aware that hypertension may occur both during maximum corticosteroid use and during corticosteroid reduction.

Adolescent↗
PubMed1992

Decreased low-density lipoprotein receptor function and mRNA levels in lymphocytes from uremic patients.

The mechanisms by which renal failure causes hyperlipoproteinemia remain unclear. To investigate the potential role of the low-density lipoprotein (LDL) receptor in lipoprotein metabolism in uremia we measured LDL receptor function in peripheral blood mononuclear cells (PBMC) from uremic patients and control subjects using a functional assay in which proliferation of lectin-stimulated PBMC in the presence of lovastatin was dependent upon internalization of exogenous cholesterol via a functional LDL receptor. The amount of LDL required to reverse 50% of lovastatin-induced inhibition of proliferation in PBMC from uremic patients was significantly greater (3.6 +/- 1.8 micrograms/ml, N = 33, P < 0.05) than controls, (1.99 +/- 0.6 micrograms/ml, N = 37). Abnormal LDL receptor function in four uremic patients normalized following renal transplantation. To investigate the molecular basis for LDL receptor dysfunction, we directly quantitated LDL receptor messenger RNA (mRNA) in PBMC from uremic patients and control subjects using a ribonuclease protection assay. LDL receptor mRNA expression in uremic patients was 0.42 +/- 0.08 (N = 10), significantly lower (P < 0.015) than in normal subjects, 0.71 +/- 0.08 (N = 14). These data suggest that an acquired defect in LDL receptor function in PBMC from uremic patients exists which may be due to decreased LDL receptor expression. These abnormalities, if present in other tissues, could contribute to the aberrant lipoprotein metabolism which is a consistent feature of uremia.

Adolescent↗
PubMed1991

Fungal peritonitis in children treated with peritoneal dialysis and gastrostomy feeding.

Feeding gastrostomies were placed in three children treated with chronic peritoneal dialysis at our center because of persistent, severe malnutrition and inadequate growth. Two had frequent fungal infections of the gastrostomy site and all three developed Candida peritonitis which occurred at 1 month, 2 months and 2 years after insertion of gastrostomy. Complications included multiple intra-abdominal adhesions, abscess formation and loss of peritoneal function necessitating transfer to hemodialysis. The presence of a gastrostomy may predispose to the development of fungal peritonitis with its high morbidity and should be avoided in children on chronic peritoneal dialysis.

Adolescent↗
PubMed1991

Efficacy of 24-hour ambulatory blood pressure monitoring in children.

OBJECTIVES: To determine whether the use of an ambulatory blood pressure monitor (ABPM) is feasible and gives accurate readings in children, and to provide data on normal daily blood pressures (BPs) and BP patterns in children. DESIGN: Cohort. SUBJECTS: Ninety-nine healthy fifth-grade students. INTERVENTIONS: Students wore an ABPM for 24 hours while recording their activities in diaries. Before and after the study period, each subject had three BPs simultaneously measured with the ABPM and a mercury manometer to assess the accuracy of the ABPM. An activity scale was retrospectively applied to diary entries to help explain the variety of BP patterns noted during data analysis. RESULTS: Systolic BPs obtained with the ABPM at the beginning and end of the study were slightly higher than those obtained with a mercury manometer; diastolic BPs were virtually identical. A circadian pattern of BPs was noted: mean systolic and diastolic BPs were higher during the day than at night. The BP patterns ranged from "hypoactive" (little baseline variation) to "hyperactive" (wide fluctuations with spikes to elevated BP ranges) during various activities. In general, higher BPs were noted at times of increased activity or emotional levels. CONCLUSIONS: Ambulatory BP monitoring was well tolerated, and measurements were reproducible and accurate. The variety of BP measurements noted at different activity levels indicate that a child's activity should be considered during data analysis. As further experience is gained, the ABPM should prove helpful in diagnosis and management of hypertension in children.

Ambulatory Care↗
PubMed1991

Familial renal adysplasia.

Renal dysplasia and agenesis as isolated findings are usually considered sporadic, noninherited abnormalities. We report three kindreds with familial renal adysplasia. Two or more children were affected in each of the families and at least one member--whether proband, sibling, or parent--had a clinically silent anomaly. Normal kidneys in the parents did not preclude the occurrence of renal adysplasia in more than one child. The empiric risks for offspring and first-degree relatives were 50% and 25%, respectively, suggesting a strong genetic factor such as a major dominant gene with variable expression. Because the disease appears to be genetic in some cases of renal adysplasia, careful screening of the proband's family, subsequent children, and pregnancies is important for the purpose of accurate genetic counseling.

Adult↗
PubMed1990

Pancreatitis in children on chronic dialysis treated with valproic acid.

Four children treated with maintenance dialysis, three peritoneal and one hemodialysis, developed pancreatitis while receiving valproic acid (VPA) for chronic seizure disorders. Two patients recovered, eventually resuming VPA therapy after successful cadaveric renal transplantation. Two children died after complications of pancreatitis. No episodes of pancreatitis occurred in the other 74 children in this maintenance dialysis population; none of whom received VPA. Although pancreatitis is a known complication of VPA treatment or end-stage renal disease (ESRD), this is the first reported series specifically relating pancreatitis to VPA administration in children treated with maintenance dialysis. The literature related to the association of pancreatitis with VPA administration and ESRD therapy is briefly reviewed and the clinical implications are discussed.

Child↗
PubMed1990

Predicting neonatal morbidity after perinatal asphyxia: a scoring system.

Predicting immediate neonatal morbidity after perinatal asphyxia has been difficult. A review of asphyxiated neonates greater than or equal to 36 weeks' gestation admitted to The Children's Hospital Newborn Intensive Care Unit in 1983 was conducted to devise a scoring system that would rapidly predict organ dysfunction observed in the immediate neonatal period. Comparison of potential score components to morbidity by multiple regression analysis yielded significant association with abnormalities in fetal heart rate monitoring, the 5-minute Apgar score, and neonatal base deficit. A scoring system was devised whose sensitivity (93.8%) and specificity (81.3%) were more predictive than any of its individual components. Prospective analysis in a similar population in 1984 validated its ability to distinguish severe from moderate morbidity after asphyxia. Positive predictive value for the score in the combined study groups (n = 98) was 79% and the negative predictive value was 83%. The scoring system may offer a rapid and accurate prediction of organ dysfunction in the immediate neonatal period after asphyxia.

Asphyxia Neonatorum↗
PubMed1990

Diagnosis of adolescent hypertension on initial screening by the use of height age.

The tremendous variability in growth and maturation during adolescence makes body mass a better determinant of blood pressure (BP) than chronologic age (CA). To evaluate whether two accepted indicators of body mass, height age (HA), and weight age (WA) could accurately predict hypertension on initial screening, 1426 healthy adolescents had their BP, height, and weight measured and Tanner stage assessed. The mean of three BP measurements were compared to eight published nomograms which correlate BP with height, weight, or CA. Patients with an initial elevated BP (greater than 95 percentile for height, weight or CA) were reevaluated to verify persistent hypertension. Eighty-seven (6.1%) initially appeared to be hypertensive with 0.84% persistently hypertensive. The diagnosis of hypertension varied considerably when the BP measurements were reevaluated based on HA or WA. Height age was the most sensitive (100%) and specific (62.6%) criteria for the diagnosis of hypertension and can be used for initial BP screening in this age group.

Adolescent↗
PubMed1987

Unexpected seizures during hemodialysis. Effect of dialysate prescription.

To assess the effects of the dialysate prescription on the intradialytic neurological stability of children requiring chronic hemodialysis (HD), continuous EEG monitoring (CEM) was performed on five children before, during and after HD against: (1) low sodium acetate (LAc: Na 132 mEq/l, acetate 38 mEq/l); (2) high sodium acetate (HAc: Na 144 mEq/l, acetate 41 mEq/l), and (3) low sodium bicarbonate (LBi: Na 133 mEq/l, bicarbonate 35 mEq/l) dialysate. Three children, two with clinically well-controlled seizure disorders and one with no seizure history, exhibited subclinical seizures on LAc and HAc but improved neurological stability on LBi. Two children had essentially unchanged CEM studies on any HD regimen. Symptoms of disequilibrium were noted in four of the five children on LAc, two of the five on HAc and only one of the five on LBi. The data suggest that bicarbonate HD may enhance intradialytic neurological stability, particularly in children with known seizure disorders. Furthermore, CEM was found to be a useful tool for evaluating the neurological stability of children during HD.

Adolescent↗
PubMed1986

Use of beta 2 microglobulin to diagnose tubulo-interstitial renal lesions in children.

Fractional excretion (FE) of beta 2 microglobulin (beta 2M) was studied in children with glomerular (N = 114), tubular (N = 50) or other (N = 18) renal diseases. FE-beta 2M (normal less than 0.36%) was significantly (P less than 0.001) lower in glomerular diseases (mean 0.104%) than in tubular lesions (mean 4.27%). Unexpectedly, several patients with glomerular disease were found to have increased values for FE-beta 2M. To determine whether this was due to a tubular component in a primary glomerular disease process, FE-beta 2M was measured in 30 children with various glomerulopathies who underwent renal biopsy. Thirteen of these patients had tubulo-interstitial lesions in addition to their glomerular disease. FE-beta 2M in these patients averaged 3.76% (range 0.14 to 44.6%); only two results were normal. Mean FE-beta 2M in the 17 patients without biopsy evidence of tubulo-interstitial disease was 0.063% (range 0.02 to 0.34%); all values were in the normal range. The types of glomerular diseases in the two groups of patients were similar. Patients with a glomerular lesion complicated by tubulo-interstitial lesions had a poorer prognosis than did those with a pure glomerular disease. The high incidence of tubulo-interstitial lesions in patients with glomerular diseases was unexpected. Our data demonstrates that FE-beta 2M represents a reliable non-invasive method to diagnose such involvement. Measurements of beta 2M also provide a convenient method to follow the course and response to treatment of renal tubular injury.

Adolescent↗
PubMed1985

Urinary beta 2-microglobulin in full-term newborns: evidence for proximal tubular dysfunction in infants with meconium-stained amniotic fluid.

Urinary concentrations of beta 2-microglobulin (beta 2M) and creatinine were measured in normal term infants and in those born with meconium-stained amniotic fluid. None of the infants or their mothers had conditions known to modify beta 2M excretion. Measurements of beta 2M were made on urines collected by bagging; urines obtained from diapers were not satisfactory. Urinary beta 2M concentrations increased significantly (P less than .02) in the normal infants from the first day (0.36 +/- 0.29 mg/L: n = 29) to the third day (0.60 +/- 0.43 mg/L: n = 21) postpartum. Compared with the normal infants, values for the infants with meconium-stained amniotic fluid were increased significantly on days 1 (1.64 +/- 2.16 mg/L: n = 25: P less than .005) and 3 (2.12 +/- 2.04 mg/L: n = 23: P less than .005). Levels exceeded two standard deviations above the normal mean in 12 of the 26 infants with meconium-stained amniotic fluid on postpartum day 1, and 12 of the 23 infants with meconium-stained amniotic fluid on day 3. Urinary creatinine levels were similar in both the normal infants and those with meconium-stained amniotic fluid. All infants with meconium-stained amniotic fluid with a one-minute Apgar score of 6 or less had an elevated urinary beta 2M concentration. The elevated levels of urinary beta 2M in infants with meconium-stained amniotic fluid indicate the existence of tubular dysfunction, probably mild acute tubular necrosis secondary to hypoxia.

Amniotic Fluid↗
PubMedDate not supplied

Hypertension in children.

Early identification of children at risk for hypertension, proper evaluation, and appropriate management is important to prevent the serious long-term complications associated with the condition. This article defines primary and secondary hypertension in children, describes accurate blood pressure measurement techniques in children, presents the evaluation of a child with hypertension, and discusses therapy and prevention.

Adolescent↗
PubMedDate not supplied

Population studies of ambulatory blood pressure monitoring in Brazilian children.

BACKGROUND: The determination of hypertension in a given population depends on the knowledge of population norms for blood pressure. This is true for both casual blood pressure (CBP) measurements and the newest and most promising technology of ambulatory blood pressure monitoring (ABPM). OBJECTIVE: To design an ambitious multinational co-operative study to determine normal blood pressure data in Brazilian children. METHODS: The study was designed to determine normative data for CBP, using the Task Force technical recommendations for age-, sex- and height-percentile-specific blood pressure values. The proposed procedure is as follows. ABPM will be studied in a random subgroup of individuals, to develop similar normative data. These data will be correlated to CBP measurements and to echocardiographic findings as a measure of end-organ damage. All patients who are diagnosed by CBP measurement to be hypertensive will also be studied by ABPM, and studies of target-organ damage will be performed. Family and medical histories will be evaluated by questionnaire and first-degree relatives will be evaluated for CBP measurement. Hypertensive patients will form a cohort for long-term follow-up. These data will be the foundation for studies of hypertension in Brazilian children.

Adolescent↗