Ordering genes in a flagella pathway by analysis of expression kinetics from living bacteria.

The recent advances in large-scale monitoring of gene expression raise the challenge of mapping systems on the basis of kinetic expression data in living cells. To address this, we measured promoter activity in the flagellar system of Escherichia coli at high accuracy and temporal resolution by means of reporter plasmids. The genes in the pathway were ordered by analysis algorithms without dependence on mutant strains. The observed temporal program of transcription was much more detailed than was previously thought and was associated with multiple steps of flagella assembly.

The incoherent feed-forward loop accelerates the response-time of the gal system of Escherichia coli.

Complex gene regulation networks are made of simple recurring gene circuits called network motifs. One of the most common network motifs is the incoherent type-1 feed-forward loop (I1-FFL), in which a transcription activator activates a gene directly, and also activates a repressor of the gene. Mathematical modeling suggested that the I1-FFL can show two dynamical features: a transient pulse of gene expression, and acceleration of the dynamics of the target gene. It is important to experimentally study the dynamics of this motif in living cells, to test whether it carries out these functions even when embedded within additional interactions in the cell. Here, we address this using a system with incoherent feed-forward loop connectivity, the galactose (gal) system of Escherichia coli. We measured the dynamics of this system in response to inducing signals at high temporal resolution and accuracy by means of green fluorescent protein reporters. We show that the galactose system displays accelerated turn-on dynamics. The acceleration is abolished in strains and conditions that disrupt the I1-FFL. The I1-FFL motif in the gal system works as theoretically predicted despite being embedded in several additional feedback loops. Response acceleration may be performed by the incoherent feed-forward loop modules that are found in diverse systems from bacteria to humans.

Transcriptional gene expression profiles of colorectal adenoma, adenocarcinoma, and normal tissue examined by oligonucleotide arrays.

Using an oligonucleotide array containing sequences complementary to approximately 3200 full-length human cDNAs and 3400 expressed sequence tags (GeneChip, Affymetrix), mRNA expression patterns were probed in 18 colon adenocarcinomas and 4 adenomas. Paired normal tissue was available and analyzed for each of the tumors. Relatively few changes in transcript expression are associated with colon cancer. Nineteen transcripts (0.48% of those detected) had at least 4-10.5-fold higher mRNA expression in carcinoma compared with paired normal samples, whereas 47 transcripts (1.3% of those detected) had at least 4-38-fold or lower expression in the tumor tissue compared with the normal samples. Some of these differences were confirmed by reverse transcription-PCR. Many of these transcripts were already known to be abnormally expressed in neoplastic tissue in general, or colon cancer in particular, and several of these differences were also observed in premalignant adenoma samples. A two-way hierarchical clustering algorithm successfully distinguished adenoma from adenocarcinoma and normal tissue, generating a phylogenetic tree that appropriately represented the clinical relationship between the three tissue types included in the analysis. This supports the concept that genome-wide expression profiling may permit a molecular classification of solid tumors.

The coherent feedforward loop serves as a sign-sensitive delay element in transcription networks.

Recent analysis of the structure of transcription regulation networks revealed several "network motifs": regulatory circuit patterns that occur much more frequently than in randomized networks. It is important to understand whether these network motifs have specific functions. One of the most significant network motifs is the coherent feedforward loop, in which transcription factor X regulates transcription factor Y, and both jointly regulate gene Z. On the basis of mathematical modeling and simulations, it was suggested that the coherent feedforward loop could serve as a sign-sensitive delay element: a circuit that responds rapidly to step-like stimuli in one direction (e.g. ON to OFF), and at a delay to steps in the opposite direction (OFF to ON). Is this function actually carried out by feedforward loops in living cells? Here, we address this experimentally, using a system with feedforward loop connectivity, the L-arabinose utilization system of Escherichia coli. We measured responses to step-like cAMP stimuli at high temporal resolution and accuracy by means of green fluorescent protein reporters. We show that the arabinose system displays sign-sensitive delay kinetics. This type of kinetics is important for making decisions based on noisy inputs by filtering out fluctuations in input stimuli, yet allowing rapid response. This information-processing function may be performed by the feedforward loop regulation modules that are found in diverse systems from bacteria to humans.

Random urine calcium/osmolality in the assessment of calciuria in children with decreased muscle mass.

BACKGROUND: Random urine Ca/creatinine (UCa/Cr) is used to estimate 24-hour Ca excretion. However, due to decreased urine creatinine excretion in children with decreased muscle mass (DMM), UCa/Cr overestimates their Ca excretion. OBJECTIVE: To evaluate whether in children with DMM random urine Ca/osmolality (UCa/Osm) can accurately predict hypercalciuria (24-hour urine Ca > 4.0 mg/kg) and at which "cutoff" value. METHODS: 19 children with DMM and 29 with normal muscle mass (NMM), ages 6 - 17 years, were studied. DMM was diagnosed based on clinical findings and decreased serum creatinine, and confirmed by low urine creatinine excretion. Over 24 hours, subjects collected each void separately. After each sample was analyzed, samples of each participant were combined to form a 24-hour specimen from which an aliquot (AL) was obtained; 24-hour urine Ca was first correlated with the corresponding AL Ca/Cr and Ca/Osm. As an internal control, a similar assessment ofproteinuria was conducted. In the next step, AL data were compared with individual urine samples to identify the time of day when a random sample best correlates with AL. RESULTS: The correlation coefficient between 24-hour Ca and AL Ca/Cr in all children was 0.61, in NMM 0.96, and in DMM 0.69 (in all p < 0.001). The correlation coefficient between 24-hour urine Ca and AL Ca/Osm in all children was 0.90, in NMM 0.90, and in DMM 0.91 (in all p < 0.001). In children with DMM, the correlation coefficient of 24-hour protein with AL protein/Cr was 0.75, and with protein/Osm 0.98 (both p < 0.001). Receiver operating characteristic curves showed UCa/Cr as a better predictor of 24-hour Ca > 4.0 mg/kg in NMM, whereas UCa/Osm was a better predictor of hypercalciuria in DMM patients. In NMM, UCa/Cr ratio > 0.20 had sensitivity of 88% and specificity of 96% in detecting 24-hour Ca > 4.0 mg/kg, whereas in those with DMM UCa/Osm (x 10) ratio of > 0.25 had sensitivity of 100% and specificity of 93% in detecting hypercalciuria. It was further found that random urine specimens collected between 9:00 a.m. and 2:00 p.m. best represented 24-hour urine data. CONCLUSION: In children with DMM, UCa/Osm can successfully replace UCa/Cr as a screening tool for hypercalciuria.

Effects of parathyroid hormone and 1,25-dihydroxyvitamin D3 on tubular handling of phosphate in hypophosphatemic rickets.

A controlled metabolic study to examine the effects of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) treatment on the renal handling of phosphate was conducted in nine patients with X-linked dominant hypophosphatemic rickets, including one with autonomous secondary hyperparathyroidism. Administration of 1,25(OH)2D3 resulted in uniform reduction in serum PTH from 63.6 +/- 14.7 (SD) to 49.3 +/- 14.8 muleq/ml (P less than 0.01), elevation of the tubular threshold for phosphate (TmP/GFR) from 1.41 +/- 0.30 to 1.90 +/- 0.31 mg/dl (P less than 0.01) and increase in serum phosphate from 2.6 +/- 0.7 to 3.4 +/- 1.1 mg/dl (P less than 0.01) in eight PTH-suppressible patients. Four patients treated with phosphate before and during the study (group A) excreted significantly more phosphate than those not treated with phosphate (group B) (P less than 0.001). In the control period, group A also had depressed TmP/GFR and higher concentrations of serum phosphate and PTH. With 1,25(OH)2D3 treatment, serum phosphate in group A became remarkably higher than in group B, 4.28 +/- 0.99 vs. 2.55 +/- 0.31 mg/dl (P less than 0.02), whereas serum PTH and TmP/GFR were similar in both groups. A good inverse linear correlation was found between mean serum PTH and mean TmP/GFR of the groups before and after treatment (r = 0.947); whereas, no correlation was found between TmP/GFR and serum calcium. The patient with autonomous secondary hyperparathyroidism, who was also treated with phosphate, had the lowest TmP/GFR. Administration of 1,25(OH)2D3 had no effect on the serum PTH and phosphate concentrations or on TmP/GFR. We conclude that in patients with X-linked dominant hypophosphatemic rickets PTH modulates to some extent the tubular handling of phosphate, and that the importance of this mechanism increases with therapeutic phosphate supplementation. Simultaneous administration of 1,25(OH)2D3 suppressed PTH activity, raised serum phosphate concentrations, and elevated TmP/GFR.

Intravenous pyelography in children with urinary tract infection and vesicoureteral reflux.

In a previous study of the radiologic evaluation of children with urinary tract infection it was recommended that IVP be performed in all patients with either abnormal ultrasonographic or voiding cystourethrographic findings. However, the benefit from IVP was believed to be questionable in children with normal ultrasonography findings and vesicoureteral reflux of only a low grade (I or II of V). To gain a better understanding of the need for IVP in the radiologic evaluation of such children, the database was expanded and the findings concerning ultrasonography and IVP were analyzed in 52 children with urinary tract infection and vesicoureteral reflux seen during the last 3 years. Of a total of 72 instances of reflux, 44 (61.1%) were of low grade (I or II), 14 of medium grade (III), and 14 of high grade (IV or V). Of the 44 urinary systems with low-grade reflux, results were as follows: renal ultrasonography appeared normal in 38 and in 34 of these, the IVP also appeared normal; in the other four, only minor and negligible changes were seen with IVP. Surgical intervention was not necessary in any of these 38 urinary systems. In six systems with low-grade vesicoureteral reflux but with abnormal ultrasonography findings, IVP results were also abnormal, and surgery was necessary in two instances. Of the 14 urinary systems with medium-grade reflux, ultrasonography appeared normal in ten but in six of these the IVP appeared abnormal.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of hydrochlorothiazide and amiloride in renal hypophosphatemic rickets.

The effects of thiazide diuretics on serum phosphate concentration, renal tubular threshold for phosphate, and urinary calcium excretion in children with renal hypophosphatemic rickets were studied. There were nine controlled acute studies conducted in five patients, and, in addition, seven long-term studies of up to 26 months were performed. During the acute studies, the children continued to receive the same doses of oral calcitriol and phosphate supplementation as at home. Hydrochlorothiazide, 1.50 to 2.25 mg/kg/d, was used alone in the first four studies; hydrochlorothiazide and amiloride at a dose of 1 mg for each 5 mg of hydrochlorothiazide were used in the other five studies. Administration of the diuretics for four days gave rise to a significant increase in serum phosphate concentration from 3.1 +/- 0.4 mg/dL to 3.7 +/- 0.9 mg/dL (P less than .01) and in tubular threshold for phosphate from 1.31 +/- 0.45 mg/dL to 1.74 +/- 0.60 mg/dL (P less than .01). These changes were accompanied by significant reductions in urinary sodium excretion from 135 +/- 39 mEq/24 h during the control period to 99 +/- 42 mEq/24 h on the fourth day of therapy (P less than .05), fractional sodium excretion from 0.99% +/- 0.42% to 0.81% +/- 0.42% (P less than .05), and urinary calcium excretion from 57.3 +/- 28.9 mg/24 h to 19.0 +/- 13.1 mg/24 h (P less than .01). Fractional excretion of phosphate divided by fractional excretion of sodium after the treatment with diuretics was not significantly different from that observed at the end of the control period. Increments in serum phosphate concentrations were correlated with elevations in serum albumin concentrations (r = .739; P less than .02). As an additional index of intravascular volume contraction, the elevations in serum phosphate concentrations were correlated with the increase in BUN, (r = .793; P less than .01). The addition of amiloride in the last five studies prevented the hypokalemia and alkalosis that had complicated the administration of hydrochlorothiazide. Long-term follow-up studies for a total of 119 therapy-months on six children and one adult, who continued to receive the diuretics concomitantly with calcitriol and phosphate supplementation, showed that they were free of complications except for a transient episode of hypercalcemia and hypercalciuria in one patient. In comparison with the previous period of treatment with calcitriol and phosphate without diuretics, linear growth velocity and healing of the rickets were not changed in two children and improved in the other four after the addition of hydrochlorothiazide and amiloride.(ABSTRACT TRUNCATED AT 400 WORDS)

Ultrasonography in the radiologic evaluation of children with urinary tract infection.

A prospective blind study comparing the findings of ultrasonography, intravenous pyelography, and voiding cystourethrography was conducted on 81 patients to examine the place of ultrasonography in the initial radiologic evaluation of children with urinary tract infection. The patients' mean age was 4.8 years; 15 were male. Forty-eight were inpatients (mean age, 3.2 years) and 33 were outpatients (mean age 7.2 years). In 29 patients (35.8%) abnormality of the urinary system was detected by one or more of the three imaging procedures; 21 were inpatients and eight were outpatients. The most frequent finding was vesicoureteral reflux, occurring in 62.1% of the pathologic cases. The findings at ultrasonography correlated well with those of intravenous pyelography in 73 of the 81 studies (90.1%), but they failed to demonstrate double collecting systems and several of the minor changes. However, ultrasonography in combination with cystourethrography identified all patients who had abnormal urinary systems, except for two children with negligible findings. Moreover, ultrasonography and cystourethrography together identified all 11 patients, nine of them inpatients, in whom surgical treatment was indicated. It is concluded that ultrasonography can successfully replace intravenous pyelography as a screening imaging procedure for the urinary system, but because of the superiority of intravenous pyelography in the detection of some types of lesions, intravenous pyelography will be required whenever ultrasonography or cystourethrography results are abnormal.(ABSTRACT TRUNCATED AT 250 WORDS)

Muscle involvement in progressive diaphyseal dysplasia.

Muscle involvement in progressive diaphyseal dysplasia was evaluated in five children, of whom four were members of one family. Age range was 2 to 10 years 9 months, and mean age was 5.5 years. Evaluation included serum enzymes, electromyography, and muscle biopsy examined by light and electron microscopy. Serum enzymes were usually noncontributory. Electromyography revealed "myopathic pattern" in four of the five patients. Muscle biopsy specimens were taken from three of the five children, including two patients from one family, of whom one had normal electromyography, and one sporadic case. Examination of the biopsy specimens by light microscope was generally not useful, whereas electron microscopic examination revealed myopathic and vascular changes consisting of atrophy of isolated muscle fibers, accumulation of endomysial collagen fibrils, and thickening of the perivascular basement membrane. The main contribution of this study is to describe electron microscopic vascular changes in muscles that appear to be similar in familial and sporadic cases of progressive diaphyseal dysplasia.

Progressive diaphyseal dysplasia: evaluation of corticosteroid therapy.

Progressive diaphyseal dysplasia is characterized clinically by crippling leg pain, fatigue, headache, poor appetite, muscle weakness, and waddling gait. Twelve affected patients, aged 2 years 4 months to 40 years, were treated with intermittent courses of low doses of prednisone given in a single dose on alternate mornings for periods ranging from 6 months to 10 years. The average initial dose of prednisone was 0.6 mg/kg/d, and average maintenance dose was 0.3 mg/kg/d. Relief of all crippling symptoms was achieved in all patients. No untoward serious side effects have been observed, and the growth of children was not slowed. However, corticosteroid therapy should be restricted to patients suffering from crippling pain. The mechanism through which steroids act remains undefined.

Progressive diaphyseal dysplasia: genetics and clinical and radiologic manifestations.

Progressive diaphyseal dysplasia was found in a three-generation family including 13 affected individuals, the largest family reported to date. Our study confirms that progressive diaphyseal dysplasia, also known as Engelmann's or Camurati-Engelmann disease, is an autosomal dominant disorder with variable osseous and muscular manifestations. Disease distribution among patients, within a given patient, or even in individual bones is unpredictable. The femur is the most commonly and severely affected bone and hence most useful for radiographic screening of possible patients. Radiographs provide a meaningful assessment of disease activity and extent. The severity of symptoms is generally proportionate to severity of involvement shown by roentgenography. Exophthalmos due to osteosclerotic dysplasia of the skull occurred in more than half of the patients with progressive diaphyseal dysplasia. Twelve-year follow-up of this family, with affected individuals ranging in age from 6 months to 12 years, indicates that progressive diaphyseal dysplasia may progress or become quiescent and be remarkably inactive despite advanced osteosclerosis and structural deformity.

Tenckhoff catheters prove superior to cook catheters in pediatric acute peritoneal dialysis.

Peritoneal dialysis (PD) is the most common form of renal replacement therapy in infants and young children with acute renal failure (ARF). The two most commonly used catheters for performing acute PD are the Cook catheter (CC), placed at the bedside, and the surgically placed Tenckhoff catheter (TC). In the present study, we compared the complications and survival rates of the two catheters. The records of 59 children (age, 1 day to 16.7 years) who underwent PD for ARF from March 1989 through June 1999 in our hospital were reviewed. The initial (primary) catheter was a TC in 22 patients and a CC in 37 patients. The age of the patients who received a primary TC (2.8 +/- 4.5 years) was no different than the age of those with a primary CC (1.4 +/- 2.0 years; P = not significant). The duration of use (mean +/- SD) of TCs (16.5 +/- 14.2 days) was significantly greater than the duration of CC use (4.9 +/- 4.2 days; P < 0.001). Only two patients with a TC (9%) developed complications, whereas 18 patients with a CC (49%) developed complications, 13 of whom required catheter replacement (P < 0.01). Thirty-five patients (59%) recovered renal function after undergoing dialysis for 11.5 +/- 8.0 days. Twenty-three of those patients (66%) required dialysis for more than 5 days. Only 4 patients with a primary CC had successful completion of dialysis without catheter-associated complications compared with 15 patients with a primary TC. Kaplan-Meier survival analysis showed that by day 6 of dialysis, only 46% of primary CCs were functioning without complications compared with 90% of TCs that were free of complications. We conclude that the use of a CC is associated with significantly more complications than a TC, and nearly one half of the CCs are likely to be nonfunctional beyond 5 days of dialysis, at a time when two thirds of the patients are still expected to be undergoing dialysis. Therefore, when possible, a TC should be the catheter of choice when initiating acute PD in children. In those patients for whom a CC is chosen as the initial catheter, an elective change to a TC should be considered once dialysis is expected to extend beyond 5 days.

Bacterial meningitis. Effect of antibiotic treatment on cerebrospinal fluid.

The effects of full short-term antibiotic treatment on cerebrospinal fluid (CSF) findings were studied retrospectively in 68 children with acute bacterial meningitis. The features of CSF at admission were compared with those of the CSF obtained after 44-68 hours of therapy. Except in one case with H. influenzae and one case with pneumococcal meningitis, all CSF cultures were negative in the repeat specimen. In three of 16 children with meningococcal meningitis, the CSF glucose levels became normal in the second specimen. In all remaining 65 children, however, full intravenous antibiotic treatment for 44-68 hours did not alter the biochemistry and cytology of the CSF, which retained its "bacterial" character. From these findings it may be discerned that partial antibiotic treatment is even less likely to distort a 'bacterial' CSF.

Pneumonia-associated acute glomerulonephritis.

OBJECTIVE: Post-infectious glomerulonephritis typically occurs 7-14days after an infection. However, in several children we observed acute glomerulonephritis (AGN) to develop concurrently with pneumonia. The objective of the study was to delineate the clinical course and outcome of pneumonia-associated AGN. STUDY DESIGN: The hospital database was searched from 1984 - 1999 for c+hildren admitted with both acute pneumonia and AGN, each diagnosis having been made within 72 hours of each other. RESULTS: 11 boys, age 3.8- 12.7 years, were identified. Ten children had lobar pneumonia and I had an interstitial infiltrate. All responded to antibiotic therapy with resolution of fever and respiratory symptoms. Only I child developed an empyema. The mean +/- SD hospital stay was 5.9 +/- 3.9 days. All patients had an abnormal urinalysis with hematuria (gross hematuria in 5), proteinuria and cellular casts. At presentation, 7 children had a serum creatinine > 1.0 mg/dl and creatinine clearance < or = 80 ml/min/1.73 m2; in all, serum creatinine returned to normal and the creatinine clearance was > 80 ml! min/1.73 m2 on follow-up. Nine of the 11 children had a low serum complement C3, 3 of whom also had low complement C4. Anti-streptolysin-O (ASO) titers were elevated in all 10 children tested. Six children developed hypertension and received antihypertensive medications. Only I child was severely oliguric requiring peritoneal dialysis for 4 days. He underwent a kidney biopsy, which showed acute proliferative glomerulonephritis without crescents. Neither a biopsy nor dialysis was performed in the other children. At follow-up, blood pressure, urinalysis and serum complements had normalized in the 9 children in whom follow-up was available. CONCLUSION: Children with pneumonia who are found to have abnormal urinalysis. hypertension, azotemia or oliguria should be evaluated for concomitant glomerulonephritis. In most children, pneumonia-associated AGN runs a benign course and has a good prognosis, however, in some short-term medical intervention may be necessary.

Topological generalizations of network motifs.

Biological and technological networks contain patterns, termed network motifs, which occur far more often than in randomized networks. Network motifs were suggested to be elementary building blocks that carry out key functions in the network. It is of interest to understand how network motifs combine to form larger structures. To address this, we present a systematic approach to define "motif generalizations": families of motifs of different sizes that share a common architectural theme. To define motif generalizations, we first define "roles" in a subgraph according to structural equivalence. For example, the feedforward loop triad--a motif in transcription, neuronal, and some electronic networks--has three roles: an input node, an output node, and an internal node. The roles are used to define possible generalizations of the motif. The feedforward loop can have three simple generalizations, based on replicating each of the three roles and their connections. We present algorithms for efficiently detecting motif generalizations. We find that the transcription networks of bacteria and yeast display only one of the three generalizations, the multi-output feedforward generalization. In contrast, the neuronal network of C. elegans mainly displays the multi-input generalization. Forward-logic electronic circuits display a multi-input, multi-output hybrid. Thus, networks which share a common motif can have very different generalizations of that motif. Using mathematical modeling, we describe the information processing functions of the different motif generalizations in transcription, neuronal, and electronic networks.

Subgraphs in random networks.

Understanding the subgraph distribution in random networks is important for modeling complex systems. In classic Erdos networks, which exhibit a Poissonian degree distribution, the number of appearances of a subgraph G with n nodes and g edges scales with network size as approximately N(n-g). However, many natural networks have a non-Poissonian degree distribution. Here we present approximate equations for the average number of subgraphs in an ensemble of random sparse directed networks, characterized by an arbitrary degree sequence. We find scaling rules for the commonly occurring case of directed scale-free networks, in which the outgoing degree distribution scales as P(k) approximately k(-gamma). Considering the power exponent of the degree distribution, gamma, as a control parameter, we show that random networks exhibit transitions between three regimes. In each regime, the subgraph number of appearances follows a different scaling law, approximately Nalpha, where alpha=n-g+s-1 for gamma<2, alpha=n-g+s+1-gamma for 2gamma(c), where s is the maximal outdegree in the subgraph, and gamma(c)=s+1. We find that certain subgraphs appear much more frequently than in Erdos networks. These results are in very good agreement with numerical simulations. This has implications for detecting network motifs, subgraphs that occur in natural networks significantly more than in their randomized counterparts.

Peritoneal dialysis in the neonatal period: outcome data.

Scant information exists on the prognosis of infants with renal failure who receive peritoneal dialysis in the first month of life. We reviewed the outcome of 23 such patients 1 year after the onset of renal failure. Diagnoses included acute tubular necrosis (11 infants), renal dysplasia (5), obstructive uropathy (4), polycystic kidney disease (1), renal vein thrombosis (1), and renal artery thrombosis (1). Seven of the eleven patients with acute tubular necrosis had had cardiac surgery. At 1 year, eight (35%) of the patients had died, six (26%) had a full recovery, seven (30%) were receiving long-term dialysis awaiting a transplant, and two (9%) had chronic renal failure. Effective dialysis, characterized by the reversal of metabolic disturbances or attainment of fluid balance, was accomplished in all patients. The mean duration of dialysis was 4.5 months (range, 0.1 to 12 months). The most common complications of dialysis were peritonitis and catheter exit site infection. Despite the provision of supplemental calories via nasogastric tube, the majority of patients receiving long-term dialysis showed impaired growth and mild developmental abnormalities. Peritoneal dialysis is an effective means of renal replacement therapy in the neonatal period; however, the morbidity and mortality rate for this population remains high.

Symptomatic peritoneal calcification in a child: treatment with tidal peritoneal dialysis.

OBJECTIVE: To evaluate the ability of tidal peritoneal dialysis to decrease the pain and frequency of hemoperitoneum associated with peritoneal calcification. DESIGN: Prospective case evaluation. SETTING: The Home Peritoneal Dialysis Unit, Children's Mercy Hospital. PATIENT: Seven-year old male with diffuse peritoneal calcifications, daily abdominal pain, and recurrent hemoperitoneum. INTERVENTION: Tidal peritoneal dialysis was conducted with an initial fill volume of 45 mL/kg and a tidal inflow volume of 23 mL/kg. The patient also maintained a daytime pass volume of 45 mL/kg. Duration of treatment was 7 months. RESULTS: The patient's abdominal pain resolved 2 days after initiating tidal peritoneal dialysis. No episodes of hemoperitoneum or abdominal pain have occurred for 7 months. CONCLUSION: Tidal peritoneal dialysis is a unique approach to the achievement of symptomatic relief in the patient with peritoneal calcification.

Should renal ultrasonography be done routinely in children with first urinary tract infection?

To reassess the impact of renal ultrasonography on the care of children with first febrile urinary tract infection (UTI) we conducted a computer search and review of medical records of (1) all children who were admitted to our hospital with first febrile urinary tract infection and underwent renal ultrasonography during a 25-month period beginning February 1, 1995, (2) all children diagnosed by ultrasound to have hydronephrosis during the same time period. Of a total of 124 patients with UTI, renal ultrasound appeared normal or showed evidence of acute pyelonephritis in 105 (84.7%), and in another nine (7.2%) it showed only minor findings. In 10 children (8.1%) ultrasound showed hydronephrosis and/or hydroureter. In eight of the latter 10, voiding cystourethrography showed vesicoureteral reflux; in one, posterior urethral valves; and in one, who had a unilateral nonobstructed dilatated system, cystography appeared normal. Except for the last patient, who was given prophylactic antibiotics and continued to have urinary tract infections, in no other case did ultrasound alone have any impact on the patient's management. Four children with both abnormal-appearing renal ultrasound and voiding cystourethrography required surgical intervention. One hundred of the 124 children had a voiding cystourethrogram. In 38 children it detected vesicoureteral reflux and, in another two, bladder abnormalities. Thirty-five of those with abnormal-appearing cystogram but without an indication for surgery were given prophylactic antibiotics. During the same 25-month period, 63 children without urinary tract infection were diagnosed by ultrasound with hydronephrosis. In 45 of them (71.4%) the urologic abnormality had already been detected by prenatal ultrasound. Fourteen of these 45 children (31.1%) required surgery, all for congenital anomalies related to obstructive uropathy. We conclude that routine renal ultrasonography in children with first urinary tract infection has negligible influence on their clinical management. This seems to be due to the recent widespread use, in industrialized countries, of maternal-fetal ultrasonography, which already detects a significant number of children with congenital obstructive uropathy prenatally. On the other hand imaging of the lower urinary tract is of high yield and contributes significantly to patient care. Therefore, whereas imaging of the lower urinary tract should continue to be done routinely in children with first urinary tract infection, renal ultrasound may be reserved for more select cases.