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Biomedical subjects

C A Peters

Publications and source records attributed to C A Peters.

At least 55 records · Page 3Linked to original sources
PubMed1999

Pediatric retroperitoneoscopic nephrectomy using 2 mm. instrumentation.

PURPOSE: We describe several modifications of the retroperitoneoscopic approach to nephrectomy for benign renal disease, including the use of 2 mm. instrumentation and prone patient positioning. MATERIALS AND METHODS: A total of 14 children underwent retroperitoneoscopic nephrectomy in the prone position. An inflatable dissecting device was inserted into the retroperitoneum after a small muscle splitting incision was made at the lateral border of the sacrospinalis muscle approximately 1 cm. below the costovertebral angle. After inflation the dissecting device was replaced with a 5 mm. cannula and pneumoretroperitoneum was maintained with carbon dioxide insufflation. Two 2 mm. trocars were then placed under endoscopic guidance. Dissection was performed using 2 mm. instrumentation and the specimen was retrieved through the largest port site. RESULTS: Nephrectomy was performed in 9 girls and 5 boys 3 months to 9.8 years old. The preoperative diagnosis included chronic pyelonephritis with minimal renal function, reflux with a nonfunctioning kidney, multicystic dysplastic kidney, an upper pole dysplastic moiety with an associated ureterocele and a dysplastic kidney with a vaginal ectopic ureter. Mean operative time for retroperitoneoscopic nephrectomy was 142 minutes with an estimated blood loss of less than 15 ml. Contralateral ureteral reimplantation was performed after retroperitoneoscopic dissection in 5 patients. Overall average hospital stay was 2 days and there were no complications. CONCLUSIONS: Several modifications of the retroperitoneal approach, including the use of prone patient positioning and 2 mm. instrumentation for visualization and dissection, may improve the safety and efficacy of this technique in children.

Child↗
PubMed1998

Heat-shock protein-25/27 phosphorylation by the delta isoform of protein kinase C.

Small heat-shock proteins (sHSPs) are widely expressed 25-28 kDa proteins whose functions are dynamically regulated by phosphorylation. While recent efforts have clearly delineated a stress-responsive p38 mitogen-activated protein-kinase (MAPK)-dependent kinase pathway culminating in activation of the heat-shock (HSP)-kinases, mitogen-activated protein-kinase-activated protein kinase-2 and -3, not all sHSP phosphorylation events can be explained by the p38 MAPK-dependent pathway. The contribution of protein kinase C (PKC) to sHSP phosphorylation was suggested by early studies but later questioned on the basis of the reported poor ability of purified PKC to phosphorylate sHSP in vitro. The current study re-evaluates the role of PKC in sHSP phosphorylation in the light of the isoform complexity of the PKC family. We evaluated the sHSP phosphorylation status in rat corpora lutea obtained from two stages of pregnancy, mid-pregnancy and late-pregnancy, which express different levels of the novel PKC isoform, PKC-delta. Two-dimensional Western blot analysis showed that HSP-27 was more highly phosphorylated in vivo in corpora lutea of late pregnancy, corresponding to the developmental stage in which PKC-delta is abundant and active. Late-pregnant luteal extracts contained a lipid-sensitive HSP-kinase activity which exactly co-purified with PKC-delta using hydroxyapatite and S-Sepharose column chromatography. To determine whether there might be preferential phosphorylation of sHSP by a particular PKC isoform, purified recombinant PKC isoforms corresponding to those PKC isoforms detected in rat corpora lutea were evaluated for HSP-kinase activity in vitro. Recombinant PKC-delta effectively catalysed the phosphorylation of sHSP in vitro, and PKC-alpha was 30-50% as effective as an HSP-kinase; other PKCs tested (beta1, beta2, epsilon and zeta) were poor HSP-kinases. These results show that select PKC family members can function as direct HSP-kinases in vitro. Moreover, the observation of enhanced luteal HSP-27 phosphorylation in vivo, in late pregnancy, when PKC-delta is abundant and active, suggests that select PKC family members contribute to sHSP phosphorylation events in vivo.

Animals↗
PubMed1998

Association of PKC delta and active Src in PMA-treated MCF-7 human breast cancer cells.

Phorbol ester treatment of MCF-7 cells led to the tyrosine phosphorylation and activation of PKC delta. However, through Western blot analysis and in vitro immunecomplex kinase assays, we detected a differential localization of tyrosine-phosphorylated PKC delta and catalytically active PKC delta. Catalytically active PKC delta was concentrated in Triton X-100 solubilized-membrane fractions while tyrosine-phosphorylated PKC delta was localized to the cytosol fraction. Phorbol ester treatment of MCF-7 cells stimulated both the time-dependent in vivo association of Src with PKC delta, evidenced in Src immunoprecipitates by the co-immunoprecipitation of PKC delta, and activation of Src, evidenced in Src immunoprecipitates as an increase in reactivity with a Src antibody (clone 28) reactive only with active Src (dephosphorylated on residue 530) and in Src and PKC delta immunoprecipitates by an increase in Src kinase activity. While our data are consistent with reports in the literature showing the activator/stimulus-dependent tyrosine phosphorylation of PKC delta, our data show that the tyrosine phosphorylation of PKC delta is not essential for kinase activity. These results are the first to demonstrate an in vivo association between PKC delta and active Src in the absence of over-expression of either PKC delta or Src, and support the association of Src and PKC delta towards a physiological function.

Breast Neoplasms↗
PubMed1998

Urachal anomalies: defining the best diagnostic modality.

OBJECTIVES: Urachal abnormalities are uncommon and the literature is primarily comprised of case reports. Conclusions regarding the presentation and diagnosis of these abnormalities may be elucidated by reviewing a large experience. METHODS: The records of 45 patients with urachal abnormalities in the pediatric age group were reviewed from 1970 to 1997. This included 24 boys and 21 girls with an age range from 1 day to 20 years (average 4.0 years). The presenting complaint was periumbilical discharge in 19 patients (42%), umbilical cyst or mass in 15 (33%), abdominal or periumbilical pain in 10 (22%), and dysuria in 1 (2%). The diagnosis consisted of a urachal sinus in 22 children (49%), a urachal cyst in 16 (36%), and a patent urachus in 7 (15%). Various radiographic studies were used to establish the diagnosis. RESULTS: Patients with a urachal sinus had 16 voiding cystourethrograms performed (only 1 diagnostic), 9 sinograms (all diagnostic), 8 ultrasounds (4 diagnostic), and 1 excretory urogram (normal). Those with a urachal cyst had 8 voiding cystourethrograms (1 diagnostic), 5 excretory urograms (all normal), 4 ultrasounds (all diagnostic), and 1 computed tomography scan (diagnostic). Children with a patent urachus had 2 excretory urograms (both diagnostic), 1 voiding cystourethrogram (diagnostic), and 2 ultrasounds (normal). One baby with a patent urachus was diagnosed prenatally during ultrasound screening. The diagnosis was made by history and physical examination alone in 5 children and at the time of surgery in 1. Treatment consisted of surgical excision of the urachal abnormality with a cuff of bladder in 22 children, surgical excision without a bladder cuff in 22, incision and drainage of a urachal cyst (1%), and laparoscopic excision of a patent urachus with a bladder cuff in another (1%). There were three wound infections postoperatively. None developed any long-term sequelae. CONCLUSIONS: The diagnosis of urachal abnormalities can be made with certainty if a good physical examination and the appropriate radiographic test are performed. A patient who presents with periumbilical drainage should have a sinogram performed, which should be diagnostic for both a urachal sinus and a patent urachus. Any child who presents with a periumbilical mass should have an ultrasound performed, which should be diagnostic for a urachal cyst.

Adolescent↗
PubMed1998

Percutaneous nephrolithotomy in infants and preschool age children: experience with a new technique.

OBJECTIVES: To develop a less invasive method for performing percutaneous nephrolithotomy (PCNL) with the intent of decreasing the morbidity of the procedure in young children. METHODS: A novel percutaneous renal access technique ("mini-perc") was developed using an 11F peel-away vascular access sheath. Tract dilation and insertion of the sheath into the collecting system was performed with a single pass over an access wire. PCNL was performed using pediatric instruments and electrohydraulic lithotripsy. Sheath design improvements were implemented that make it specific for pediatric PCNL. RESULTS: Eleven procedures have been performed with the 11F sheath. Patient age ranged from 2 to 6 years (mean 3.4) and weight from 5 to 24 kg (mean 12.5). The average stone burden was 1.2 cm2. Mean procedure time, estimated blood loss, and length of hospitalization were 203 minutes, 25 mL, and 6 days, respectively. Six (85%) of 7 patients are currently stone free with an average follow-up of 12 weeks. No patient required transfusion, developed urosepsis, or had a procedure-related complication. One procedure was performed in an outpatient setting with no postoperative nephrostomy tube. CONCLUSIONS: The 11F "mini-perc" technique was successful in rendering 85% of patients stone free with minimal morbidity. Its advantages over obtaining access with standard 24 to 34F access sheaths include a smaller skin incision, single-step dilation and sheath placement, good working access for pediatric instruments, variable length, and lower cost. In addition, the hypothesized decrease in renal and body wall trauma may result in less pain, reduced severity or risk of complications, and shorter hospital stays including the possibility of performing "tubeless" outpatient PCNLs. Further study is needed to confirm these possibilities.

Child↗
PubMed1998

A single-system ectopic ureter draining an ectopic dysplastic kidney: delayed diagnosis in the young female with continuous urinary incontinence.

OBJECTIVE: To document the array of diagnostic modalities, the variety of errant diagnoses and treatments. and the time from initial presentation to ultimate diagnosis in girls with an ectopic single-system ureter draining an ectopic hypoplastic and/or dysplastic kidney. PATIENTS AND METHODS: Between 1990 and 1997, seven females were identified who had an ectopic hypoplastic and/or dysplastic kidney with an ectopically draining ureter, and who were treated at our institutions, either initially or upon referral. The nature and number of all diagnostic evaluations, previous diagnoses and treatments, and the time from presentation to definitive diagnosis were recorded. RESULTS: All seven females had a classical history of successful toilet training, a normal voiding pattern and continuous urinary incontinence. Typically, a solitary kidney was noted on the initial diagnostic evaluation by ultrasonography and/or intravenous urography. The mean (range) age at initial presentation was 3.2 (2-6) years. Additionally, voiding cysto-urethrography, urodynamics, radionuclide scintigraphy, computed tomography, magnetic resonance imaging and endoscopy were performed. The age at definitive diagnosis was 3-16.5 years and the mean (range) time from initial presentation to diagnosis was 5.7 (1-10) years. Nephroureterectomy was curative and all kidneys were dysplastic. CONCLUSION: Continuous urinary incontinence in females with a normal voiding pattern should prompt an evaluation for ureteric ectopia. When the initial evaluation yields the diagnosis of a solitary kidney, clinicians should be aware of the possibility of a hypoplastic and/or dysplastic, often ectopic, contralateral kidney with an ectopically draining ureter. Identification of this entity should allow curative surgical treatment.

Adolescent↗
PubMed1998

Pneumoperitoneum produces reversible renal dysfunction in animals with normal and chronically reduced renal function.

Laparoscopic surgery with intraperitoneal insufflation is associated with acute oliguria. Although in healthy patients, this impairment is transient and without any apparent sequelae, as the scope of laparoscopic surgery expands, subtle renal injury may become clinically significant, particularly when applications expand to patients with reduced baseline renal function. We have investigated the changes in renal function during and after pneumoperitoneum in animals with reduced renal mass to identify both acute alterations and long-term impairments, if any. Twelve swine underwent surgical reduction in renal mass to produce chronic renal insufficiency. Glomerular filtration rate (GFR) was determined by inulin clearance for each animal before and after ablation to establish the degree of renal impairment (mean 22%; range 18%-31% of normal). The animals were followed during a stepwise insufflation as a study of pneumoperitoneum-induced changes in chronic renal failure. Urine output declined dramatically (-80% at 20 mm Hg), the GFR fell (-63% at 20 mm Hg), and renal blood flow declined (mean -12%; range -9% to -19%) over the course of the test. These values did not return to baseline during a 90-minute observation period after release of the pneumoperitoneum. Acute renal failure occurred despite aggressive hydration with maintenance of central venous pressure and only modest changes in cardiac output. The animals were exposed to a 6-hour CO2 pneumoperitoneum to 20 mm Hg to model the insult of complex laparoscopy. This exposure resulted in elevation of the amount of N-methyl-beta-D-glucosaminidase being shed into the urine in addition to the previously indicated impairments. The animals were allowed to recover for 1 week, and then GFR was again measured. The GFR returned to the preexposure chronic renal failure levels for both the group as a whole and individual animals. The magnitude and duration of the alteration in urine output, GFR, and renal blood flow suggest that regulatory mechanisms rather than simple mechanical forces are involved in the acute changes. No long-term impact on renal function from the acute renal injury was identified, even in animals with existing renal insufficiency.

Abdomen↗
PubMed1998

Experimental vesicoureteral reflux in the fetus depends on bladder function and causes renal fibrosis.

PURPOSE: Prenatal diagnosis allows the early detection of vesicoureteral reflux in an increasing number of newborns, some of whom are born with impaired kidney function. This situation challenges our current understanding of the pathophysiology, natural history and, therefore, treatment of reflux. We created a fetal sheep model of vesicoureteral reflux to study the mechanisms of fetal reflux nephropathy. MATERIALS AND METHODS: Vesicoureteral reflux was induced in fetal sheep at 95 days of gestation (term 140 days) by open bladder incision of the intravesical ureteral tunnel. All animals underwent urachal ligation and in female subjects mild bladder outlet obstruction was created with a gold ring. RESULTS: At term reflux was detected in 18 of 28 renal units by filling cystography. Refluxing kidneys were hydronephrotic and larger than normal. At term mean kidney weight was 21.1 gm. (range 12.2 to 35.0) in male subjects with reflux compared to 8.5 gm. (range 6.5 to 11.3) in normal male subjects (p <0.001) and 11.5 gm. (range 8.5 to 15.8) in male subjects with urachal ligation only (p = 0.035). In female subjects there was no change in renal weight. Renal histology revealed a thin, structurally normal cortex with small subcortical cysts and a hypoplastic medulla with mesenchymal tissue replacing normal ducts. Total mean renal collagen content was significantly increased to 51.7 mg. (range 35 to 81) in the refluxing kidneys of male animals, while it was 23.8 mg. (range 12.1 to 38.4) in normal male animals (p = 0.03). The fractional excretion of sodium was elevated in refluxing kidneys based on sodium-to-creatinine ratios in bladder urine. CONCLUSIONS: In a novel model of fetal vesicoureteral reflux we showed that prenatal reflux nephropathy is characterized by altered renal growth regulation, structural maldevelopment without overt dysplasia, excess matrix deposition and impaired excretory function.

Animals↗
PubMed1998

Stretch activates heparin-binding EGF-like growth factor expression in bladder smooth muscle cells.

Cultured rat bladder smooth muscle cells (SMC) were grown on collagen-coated silicone membranes and subjected to continuous cycles of stretch-relaxation. Semiquantitative RT-PCR analysis revealed a time-dependent increase in heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF) mRNA levels after stretch, with maximal levels appearing after 4 h. Immunostaining for proHB-EGF revealed higher levels of HB-EGF protein in the stretched than in the nonstretched SMC. The ANG II receptor type 1 antagonist losartan markedly suppressed stretch-activated HB-EGF expression. ANG II levels were 3.3-fold higher in the stretch- than in the non-stretch-conditioned media. Stretch stimulation of bladder SMC that had been transiently transfected with an HB-EGF promoter-luciferase expression construct resulted in an 11-fold increase in reporter activity. Mechanical stretch induced a 4.7-fold increase in tritiated thymidine incorporation rate, and this was reduced by 25% in the presence of losartan. We conclude that mechanical stretch activates HB-EGF gene expression in bladder SMC and that this is mediated in part by autocrine ANG II secretion.

Angiotensin II↗
PubMed1998

Amiodarone induced epididymitis in children.

PURPOSE: Amiodarone is an antiarrythmic agent, which is often successfully used when all other antiarrythmics have failed. Sterile epididymitis is a recognized complication of treatment in adults, occurring in up to 11% of patients. To date there have been no reported cases of amiodarone induced epididymitis in children. We present a previously unrecognized cause of epididymitis in boys. MATERIALS AND METHODS: The medical records, including radiographic imaging, pathology and operative reports, of 2 postpubertal boys who had sterile epididymitis after prolonged therapy with amiodarone were reviewed. RESULTS: In both cases the onset of scrotal pain and subsequent evaluation led to diagnosis of epidydimitis. Amiodarone was determined to be the cause, and cessation of the drug resulted in symptom resolution in 1 case. CONCLUSIONS: While it remains uncertain, the pathophysiology of amiodarone induced epididymitis is likely related to its high concentration in testicular tissue. Recognition that amiodarone is a rare but significant cause of epididymitis in children is important to prevent unnecessary surgery in high risk patients. Amiodarone induced epididymitis in children tends to be a self-limited process and of secondary importance to the serious cardiac disease. Whereas discontinuing amiodarone risks sudden cardiac death, a reduction in dosage or temporary cessation of the drug may result in rapid resolution of the epididymitis.

Adolescent↗
PubMed1998

Current findings in diagnostic laparoscopic evaluation of the nonpalpable testis.

PURPOSE: We delineate the current findings and contribution of diagnostic laparoscopic evaluation in the management of nonpalpable testis. MATERIALS AND METHODS: We reviewed all cases in which laparoscopy was considered the management associated with a nonpalpable testis in a 4-year period. Since our previous series, we have performed a careful examination for the testis after induction of anesthesia but before committing to laparoscopy. We recorded testis position and quality, character of the vas deferens and spermatic vessels, type of management and contribution of laparoscopy. We also reviewed contemporary published series and collated the findings of studies performed elsewhere. RESULTS: We identified 263 nonpalpable testes in 225 patients between September 1992 and 1996. In 40 patients 46 testes (18%) were found during physical examination under anesthesia. Of the remaining cases considered appropriate for laparoscopy 215 with complete records were further analyzed. Only 12.6% could be considered missed on examination due to a viable testis distal to the inguinal ring. Of the testes 45.7% would have been found during inguinal exploration alone. In 9.8% of the patients there were intra-abdominal vanishing testes, while 4.2% had indeterminate cord structures on inguinal exploration that would have prompted abdominal extension without a laparoscopic demonstration that the vas and vessels entered the canal. A conventional inguinal incision would have provided optimal exposure for operative management in 34% of the testes. For testes distal to the internal ring when the vas and vessels were distinctly atretic we never identified a viable testis, while a normal appearing vas and vessel were associated with a 45% chance of a salvageable testis. Laparoscopy was informative regarding testis position in all cases in which it was performed. CONCLUSIONS: In 13.2% of the cases laparoscopic findings precluded unnecessary abdominal exploration. The typical surgical incision for inguinal exploration would have left the surgeon compromised in 66% of the cases compared to the approach optimized as a result of laparoscopic testicular localization. Of the patients 34% arguably did not benefit from laparoscopy versus inguinal exploration. A simple examination under anesthesia significantly decreases the number of uninformative laparoscopic evaluations, and it is well worth the cost of a few minutes of operative time.

Adolescent↗
PubMed1998

Premature urachal closure induces hydroureteronephrosis in male fetuses.

PURPOSE: Congenital hydronephrosis is more common in male individuals. We investigate whether an alteration in fetal bladder function induced by premature urachal closure contributes to fetal hydronephrosis, consequently explaining this male predominance. MATERIALS AND METHODS: The urachus was clipped in 8 male and 4 female ovine fetuses at 95 days of gestation (term 140 days). Subjects were sacrificed, and the urinary tract was assessed at 109 and 116 days of gestation in 3 and 1 male fetuses, respectively, and at term in 4 male and 4 female lambs. RESULTS: At 109 and 116 days of gestation 3 of the 4 male fetuses had upper tract dilatation. At term no female but 4 male lambs had hydroureteronephrosis, including some with marked pelvic dilatation and parenchymal thinning. At term mean bladder weight in the male animals with urachal clipping was 5.28 gm. (range 3.5 to 8.2), which was significantly greater than normal (p = 0.02). Bladder weight at term in the female lambs with urachal clipping was not different from normal values. Histological evaluation of the kidneys in the male lambs revealed cortical thinning and loss of medullary tissue, while the overall renal architecture was well preserved. CONCLUSIONS: Our observations indicate that normal ovine fetal urinary tract function and drainage depend on urachal function and the timing of urachal closure. Therefore, fetal hydronephrosis is associated with this alteration in bladder function but it may also be associated with other factors, such as bladder sphincter maturation or prostate development. Our experiment shows that hydroureteronephrosis develops in ovine fetuses when all bladder drainage occurs via the urethra. This condition may be an amplification of the differences in bladder outlet resistance in human fetuses, which may explain the male predominance in the various forms of hydroureteronephrosis.

Animals↗
PubMed1998

Reservoir calculi: a comparison of reservoirs constructed from stomach and other enteric segments.

PURPOSE: The intestinal augmented bladder has an increased propensity to form urinary calculi. Predisposing risk factors include chronic bacteriuria, urinary stasis and mucus production. Gastric reservoirs have negligible mucus production and the ability to acidify the urine. We determined whether they also have a decreased incidence of stones. MATERIALS AND METHODS: We retrospectively reviewed the records of all patients undergoing augmentation cyptoplasty (215) or creation of a freestanding reservoir (44) between May 1976 and March 1996. Of these cases 83 were augmented with stomach and 179 were constructed from other intestinal segments, (that is ileal, ileocecal, sigmoid and/or a combination of these). Presenting diagnosis, patient age, gender, additional surgical procedures, interval to stone formation and calculous composition were recorded. Patients were excluded from study when there was less than 1 year of followup, as were those with renal or pre-augmentation bladder calculi. RESULTS: Stones formed in 32 of 207 patients (15%) after an average interval of 3.6 years (range 0.5 to 8.6). The majority of stones were composed of struvite (magnesium ammonium phosphate). Reservoirs containing gastric segments were significantly less likely to form calculi than those augmented with other intestinal segments (2 of 70 versus 30 of 137, p <0.0001 Fisher's exact test). Seven additional patients with pre-augmentation bladder stones who subsequently underwent gastrocystoplasty remain stone-free at an average followup of 3.0 years. CONCLUSIONS: Calculous formation is rare in reservoirs that incorporate a gastric segment. In patients with gastric augmentation stones appear only to develop when the patient is on histamine blockade or has a propensity to form stones that only favor an acidic environment, such as uric acid.

Adolescent↗
PubMed1997

Continent urinary diversion: the Children's Hospital experience.

PURPOSE: Continent urinary diversion has become increasingly important for treating childhood urinary tract pathology that cannot be managed by direct reconstructive techniques. We review our 9-year experience with continent diversion. MATERIALS AND METHODS: Since 1986 continent diversions were created in 74 patients 3 to 38 years old (mean age 13.7). The underlying pathological condition was the exstrophy/epispadias complex in 34 patients, neurological disorders in 23, malignancy in 13 and other congenital anomalies in 4. Followup averaged 5.2 years after the last procedure. Nonbladder reservoirs in 39 patients (53%) were fashioned from ileocolic (17), colic (7), gastrocolic (6), sigmoid (3), gastrosigmoid (2), ileosigmoid (2), ileal (1) and gastroileac (1) segments. When possible, the native bladder was incorporated into the reconstructive strategy. A total of 26 patients underwent bladder augmentation with intestine or stomach, including ileal (11), gastric (8), sigmoid (3), gastroileac (2) and ileocolic (2) segments. Nine other patients did not require bladder augmentation. Continence mechanisms were a flap valve (Mitrofanoff principle) in 50 patients, nipple valve in 15 and ileal plication (Indiana pouch) in 9. When the Mitrofanoff principle was used with a native bladder reservoir in 30 cases, outlet resistance was altered by bladder neck division (15), fascial sling placement (6) or Young-Dees-Leadbetter bladder neck reconstruction (2). In the remaining 7 patients the bladder neck remained intact. RESULTS: Excellent continence was obtained. The Mitrofanoff principle initially provided continence in 41 patients (82%). Six of the 9 incontinent patients were dry after a single revision. A total of 13 patients (87%) with nipple valves and 7 (78%) with Indiana pouches were dry, and the remaining 5 were cured after a single revision. Ultimately continence was achieved in 71 of the 74 patients (96%) after a maximum of 2 operations. Of the 48 complications in 29 patients the most common were difficulty in catheterizing (11), stones (11), infection (8) and upper tract deterioration (4). CONCLUSIONS: Many options exist for reconstructing complex anomalies. Choices must be individualized based on patient anatomy. The dry state may be achieved in most cases without resorting to a bag on the abdomen.

Adolescent↗
PubMed1997

Estimating normal bladder capacity in children.

PURPOSE: An accurate estimation of normal bladder capacity can be helpful in evaluating the patient with genitourinary disease and in interpreting urodynamic data. Prior studies have provided initial estimates. We propose 2 new equations that are practical, easy to use and more accurate than those previously published. MATERIALS AND METHODS: We retrospectively reviewed the records of more than 5,000 children undergoing radionuclide cystography at our institution. Radionuclide cystography was conducted by instilling (99m)technetium pertechnetate via gravity drip in awake children. Bladder capacity was believed to be achieved when rate of inflow diminished to a minimal rate, initiation of voiding occurred or significant discomfort was indicated. Patients with vesicoureteral reflux, infravesical obstruction, urinary tract infection, dysfunctional voiding or other lower urinary tract pathology were excluded from the study. Linear and nonlinear regression modeling established the relationship between age and bladder capacity. RESULTS: A total of 2,066 children (598 boys and 1,468 girls) had normal radionuclide cystography and were included in the analysis. Analysis of variance demonstrated that increasing age was strongly predictive of bladder capacity (p <0.0001). Because a nonlinear model was the most accurate formula for all ages (4.5 x age(0.40) = capacity [ounces]), 2 practical linear equations were determined: 2 x age (years) + 2 = capacity (ounces) for children less than 2 years old, and age (years) divided by 2 + 6 = capacity (ounces) for those 2 years old or older. Although girls had larger capacities than boys, the rate of increase was not significantly different between them. CONCLUSIONS: The relationship between normal bladder capacity and age in children follows a nonlinear curve. This nonlinear relationship can be approximated by 2 practical linear formulas that are easy to remember and are derived from a larger population than any prior study. These formulas provided accurate estimations of bladder capacity when prospectively applied to normal patients.

Adolescent↗
PubMed1997

Dysregulated proteolytic balance as the basis of excess extracellular matrix in fibrotic disease.

To investigate mechanisms of tissue fibrosis, we developed a model of ovine fetal bladder fibrosis due to surgically induced obstruction. Tissues were analyzed for matrix metalloproteinases (MMPs) and their inhibitors, the tissue inhibitors of metalloproteinases (TIMPs). Active MMP-2 was not detected in obstructed bladders, while latent and active forms were detected in normal bladders. MMP-1 (interstitial collagenase) activity was lower in obstructed bladders. MMP inhibitory activity was increased with obstruction, as were levels of TIMP mRNA and protein. These results indicate that the proteins responsible for collagen degradation are present in the developing bladder, and a shift in the proteolytic balance favoring inhibition of degradation occurs in a model of obstruction-induced fibrosis. This altered proteolytic balance favors accumulation of extracellular matrix and decreased tissue compliance characteristic of this and perhaps other fibrotic conditions.

Animals↗
PubMed1997

Obstruction of the fetal urinary tract.

Understanding the mechanisms of fetal obstructive uropathy will be essential for the specific management of the wide clinical spectrum of congenital obstructive conditions, including selecting observational therapy for mild cases and attempting to maximize renal function in severe cases. Recognition of the unique aspects of fetal renal obstruction is essential to formulate a useful research program, as the lessons of postnatal acquired obstruction are not directly transferable to congenital obstruction. Experimental studies of renal obstruction have demonstrated alterations in the developmental regulation of growth and differentiation in the fetal kidney. Depending on the gestational timing and severity of obstruction, growth may be impaired or accelerated. Similarly, patterns of altered differentiation may indicate immaturity or accelerated maturation, as well as aberrant differentiation. Concomitant with altered development, there is evidence that normal renal regulatory mechanisms, including the renin-angiotensin system and renal hemodynamics, may be affected by obstruction, possibly as compensatory responses. The mechanisms of these various alterations remain to be defined, but are likely to involve combinations of biomechanical signal transduction, growth factor expression, and responses of specific renal autoregulatory mechanisms. Fetal renal obstruction remains incompletely defined. The body of experimental evidence indicates that investigation of mechanisms regulating growth and differentiation is likely to yield important understanding of fetal renal obstruction to permit more accurate prognosis and management. Viewing fetal renal obstruction as a disorder of kidney development, with disordered growth and differentiation, suggests a definition of obstruction as a condition, that--if uncorrected--will lead to impairment in the ultimate functional potential of the kidney. Intervention should aim to maximize functional potential rather than to simply maintain the status quo.

Animals↗