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Biomedical subjects

C A Peters

Publications and source records attributed to C A Peters.

At least 91 records · Page 5Linked to original sources
PubMed1994

Bowel injury in open technique laparoscopic cannula placement.

Open trocar placement is used by many surgeons during laparoscopy to avoid some of the potential complications of Veress needle and sharp trocar insertion. We describe a case of serosal bowel injury with a holding stitch placed to obtain an airtight peritoneal cavity during open laparoscopic trocar placement in a two-year-old patient. The importance of inspection of the initial umbilical puncture site is emphasized and a rapid, simple technique for repair of minor bowel injuries is described.

Child, Preschool↗
PubMed1994

Management of severe hypospadias with a 2-stage repair.

From 1986 to 1993 we treated 1,437 children with hypospadias of whom 58 had scrotal or perineal hypospadias with severe chordee and a small phallus. These patients underwent a 2-stage surgical repair. The first stage of the procedure included correction of the chordee and advancement of preputial flaps ventrally and distally to the superior aspect of the glans. After 6 to 12 months the second stage of the procedure was performed using the previously transferred preputial skin to reconstruct the glans and urethra. A second layer of subcutaneous tissue or tunica vaginalis was used in several instances. A penile nerve block and a transparent biomembrane dressing (Tegaderm) allowed for early postoperative mobilization. Excellent functional and cosmetic results were achieved. There is a subset of patients with severe proximal hypospadias, chordee and a small phallus who may benefit best from a 2-stage procedure. In these children a 2-stage repair allows for a better cosmetic appearance and a lower complication rate than a 1-stage repair with a free or vascularized graft.

Child↗
PubMed1994

Prenatal findings associated with a unilateral nonfunctioning or absent kidney.

Prenatal findings in infants who were postnatally found to have a unilaterally nonfunctioning cystic, dysplastic or absent kidney were evaluated to understand better the prenatal pathophysiology of these conditions. Of the 38 cases in which prenatal and postnatal renal imaging studies were done fetal renal conditions leading to postnatal dysplasia or absence included small echogenic kidneys in 3, typical multicystic dysplasia in 30, obstructive uropathy in 4 and perinephric urinoma in 1. Abnormalities were noted on postnatal imaging in 30% of the contralateral kidneys. Vesicoureteral reflux was the most commonly identified abnormality, occurring in 23% of the cases.

Female↗
PubMed1994

Urinary levels of the renal tubular enzyme N-acetyl-beta-D-glucosaminidase in unilateral obstructive uropathy.

Elevated urinary levels of the renal tubular enzyme, N-acetyl-beta-D-glucosaminidase (NAG), have been shown to be associated with reversible tubular damage and, therefore, may serve as an indicator of tubular damage in the setting of presumed obstruction uropathy. This study compares urinary NAG levels in children with apparent upper tract obstruction with normal children to assess the sensitivity of this assay for the detection of possible renal tubular damage. The study included 40 children 3 weeks to 16 years old with unilateral ureteropelvic junction obstruction (30) or primary obstructive megaureter (10). Urine was obtained from the bladder in all children and from the renal pelvis or ureter in 30 patients at surgery. Pelvic and ureteral urinary NAG levels were consistently higher than bladder levels. In patients with ureteropelvic junction obstruction NAG levels were 7 times higher than normal (76 units per mg., p < 0.0001) and 3 times higher than normal in patients with obstructive megaureter (29 units per mg., p < 0.001). The mean bladder urinary NAG levels in patients with ureteropelvic junction obstruction (17.6 units per mg. creatinine, standard error of mean 2.01, p < 0.001) and megaureters (19.2 units per mg. creatinine, standard error of mean 3.6, p < 0.049) were elevated above control patients (10.6 units per mg. creatinine, standard error of mean 1.02). Elevated urinary NAG levels in the renal pelvis, ureter and bladder may be helpful in identifying upper tract obstruction, which if left untreated, might cause progressive renal deterioration.

Acetylglucosaminidase↗
PubMed1994

Laparoscopic evaluation of the nonpalpable tests: a prospective assessment of accuracy.

To assess diagnostic accuracy, laparoscopy and surgical exploration were prospectively performed in 104 children with 126 nonpalpable testes. Laparoscopic localization of the testis was correct in 90% (114 of 126 testes) and was nondiagnostic in 8% largely due to preperitoneal insufflation. No surgical complications occurred. Using the criteria of blind-ending vas deferens and spermatic vessels as diagnostic of an intra-abdominal vanishing testis, the accuracy of diagnosis was 100% but the inability to identify either vas or vessels was associated with intra-abdominal testes in 2 of 3 cases. Identification of canalicular vas deferens and spermatic vessels was associated with testes in 36 of 75 cases (48%). Bilateral nonpalpable testes were significantly less likely to have an absent testes (5%) than a unilateral nonpalpable testis (59%), suggesting the possibility of different pathophysiological mechanisms in those entities. Diagnosis and surgical management of nonpalpable testes were directly impacted by laparoscopy in 42 of 117 testes (36%) by identifying intra-abdominal vanishing testis, the location of an intra-abdominal testes or the need for retroperitoneal exploration when vas deferens and spermatic vessels were not found. Accurate knowledge of testis location in 97% of the testes facilitated development of an appropriate surgical strategy (that is laparoscopic/laparoscopic assisted versus open procedure).

Adolescent↗
PubMed1994

Bladder reconstruction in children.

Bladder reconstruction in children attempts to provide for a low pressure reservoir of urine that is continent and may be emptied completely at appropriate intervals. The most common underlying causes of bladder dysfunction that may require reconstruction include neuropathic bladders associated with spina bifida, posterior urethral valves, and bladder exstrophy. Indications and patient selection for reconstruction have greatly improved and a variety of methods are available; each with its own advantages and drawbacks. The recent increased application of gastric segments in augmenting the bladder to increase size and compliance has been very successful, and particularly in patients with impaired renal function. The continent catheterizable stoma (Mitrofanoff principle), using appendix or ureter, has gained widespread acceptance in reconstructive procedures and provides a reliable, convenient, and well-accepted means of achieving continence. Although advances have been made in reconstructive techniques, new complications are being experienced, including stone formation and metabolic abnormalities. Gastrocystoplasty, although an excellent option in reconstruction, has produced a symptom complex of hematuria and dysuria in some patients, at times to a significant degree. With experience, these complications are becoming better understood and new strategies for management are being developed. On the horizon, new approaches to bladder replacement are being explored, and new investigation into the pathophysiology of pediatric bladder dysfunction is ongoing.

Child↗
PubMed1993

Does the system of Papanicolaou test nomenclature affect the rate of referral for colposcopy? A survey of family physicians.

OBJECTIVE: To determine whether a new system of Papanicolaou test nomenclature (the Bethesda system) or other physician variables influence recommendations for colposcopy and biopsy for women with borderline to moderately abnormal Papanicolaou test results. We hypothesized that physician demographic and practice variables, in addition to Papanicolaou test nomenclature, would influence recommendations for colposcopy. DESIGN: A survey was mailed to a random sample of 510 active members of the American Academy of Family Physicians. PARTICIPANTS: Three hundred thirty-five (66%) of the eligible physicians responded, representing all 50 states. Of those in active practice, 78% were in private practice, with a mean age of 44 years and a mean time in practice of 10 years. Ninety-three percent of respondents in active practice performed Papanicolaou tests. MAIN OUTCOME MEASURE: Rates of recommendation for colposcopy and biopsy in response to abnormal Papanicolaou test reports framed by a single clinical scenario. RESULTS: Physicians recommended colposcopy more often when the Bethesda nomenclature system was used to describe the results of the Papanicolaou test. These differences were significant for four specific Papanicolaou smear pairs. Inclusion of recommendations for further evaluation strongly influenced physicians to recommend colposcopy. In multivariable analyses, demographic and practice variables were not associated with recommendations for colposcopy. CONCLUSIONS: The Bethesda system of nomenclature, when compared with a traditional descriptive nomenclature system, influenced family physicians to recommend colposcopy and biopsy more often for abnormal Papanicolaou test results presented in a clinical scenario. Greater utilization of technology and higher medical care costs may result from use of the Bethesda system. Guidelines for evaluation of abnormal Papanicolaou test results are needed for use in conjunction with the Bethesda system guidelines for Papanicolaou test reports.

Adult↗
PubMed1993

Experimental fetal tracheal ligation prevents the pulmonary hypoplasia associated with fetal nephrectomy: possible application for congenital diaphragmatic hernia.

Pulmonary hypoplasia has a definite clinical impact in a variety of congenital diseases such as renal dysplasia and congenital diaphragmatic hernia. These diseases have in common inadequate growth and development of fetal lungs. Previous reports have demonstrated increased lung growth with in utero tracheal ligation. The purpose of this study was to determine if lung growth can be accelerated in the setting of experimental pulmonary hypoplasia. Ninety-five-day gestation fetal sheep were divided into four experimental groups: nephrectomy, nephrectomy with tracheal ligation, tracheal ligation alone, and sham-operated control animals. Animals were delivered near term and their lungs inflation fixed at 25 cm H2O. Total alveolar number (Alv#), total alveolar surface area (AlvSA), and lung volume to body weight ratios (LV:BW) were determined for apical and basilar segments of each animal and then averaged. Total lung DNA and protein content were also analyzed. The nephrectomy group had smaller lungs than control animals with decreased Alv#, AlvSA, and LV:BW. In contrast, nephrectomy with tracheal ligation produced large lungs which had increased Alv#, AlvSA, and LV:BW when compared with both the nephrectomy and the control group (P < .01). Total lung DNA and protein concentrations were both markedly elevated in the tracheally obstructed groups. However, the DNA/protein ratios remained constant in all four groups, suggesting that lung growth had occurred through cell multiplication. Photomicrographs of the lung demonstrated a histologically immature appearance in the nephrectomy group and a histologically mature appearance in the tracheally obstructed groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Laparoscopy in pediatric urology.

Laparoscopy has been used in pediatric urology for the diagnosis of nonpalpable testes for more than fifteen years. Expansion of pediatric urologic applications of laparoscopic surgical techniques is inevitable with the recent explosion of urologic laparoscopy. While the needs are distinct and at times divergent from those in the adult population, many benefits may be realized with this developing technology in children. Refinement of diagnostic capabilities as well as interventional procedures for the undescended testis are being developed. Increased use for varicocele treatment and intersex evaluation can be expected. Potential applications of laparoscopic techniques for the pediatric urologist include nephrectomy for various benign diseases, ureteral surgery for reflux, bladder autoaugmentation, and hernia repair. Laparoscopic possibilities are limited only by imagination and technology. A skeptical approach is justified and judicious application of these technologies in children is essential. Just as the child is not a small adult, pediatric laparoscopy is not just the use of smaller instruments.

Child↗
PubMed1993

Fetal compensatory renal growth due to unilateral ureteral obstruction.

To determine whether fetal compensatory renal growth occurs in response to early gestational unilateral renal obstruction and to help elucidate the characteristics of this response, a fetal lamb model was developed in which unilateral ureteral obstruction was created at 60 days of gestation (term 135 to 140 days) and the effects of the obstruction were studied at varying periods thereafter. Kidneys were retrieved at 2 weeks (75 days in 3 cases), 5 weeks (95 days in 4) and 10 weeks (135 days in 9) after obstruction, weighed and preserved for histology and biochemical studies. Deoxyribonucleic acid (DNA), ribonucleic acid and protein were quantitated using standard assays. Morphometric studies to estimate glomerular number were performed using standard stereological methods. Contralateral kidney weight was increased compared to normals in 55 cases at all ages. The relative difference increased from 75 to 95 days. The fractional increase at 135 days (49.5%, p < 0.001 versus normal) was not different from 95 days (46.4%, p = 0.87), indicating that growth rate acceleration occurred predominantly before 95 days. Total renal DNA was increased above normal at each time point, with an ultimate increment proportionate to weight. Protein concentration was unchanged, suggesting that weight increase was not due to changes in renal water. Protein/DNA ratios were unchanged, indicating a predominantly hyperplastic process. Ribonucleic acid/DNA ratios decreased, possibly indicating a high rate of proliferation. Total glomerular number at term did not increase with in utero compensatory renal growth. Unilateral ureteral obstruction created early in gestation produced compensatory renal growth of the intact kidney in the fetal lamb. This process demonstrates an early but transient growth rate acceleration, hyperplasia and no increase in total glomerular or nephron number. The occurrence of compensatory renal growth in the fetal kidney with minimal functional renal demand would suggest that its mechanisms may be independent of functional demand. This model is unique and well suited to study compensatory renal growth.

Adaptation, Physiological↗
PubMed1993

Laparoscopic correction of vesicoureteral reflux.

Major advances have been made in the area of laparoscopic surgery. The advantages of this approach include smaller incisions, shorter hospitalizations, a more rapid convalescence and decreased postoperative discomfort. To explore the technical feasibility of performing antireflux surgery laparoscopically, we conducted a pilot study in 4 mini-pigs in which bilateral vesicoureteral reflux had been created surgically. We applied a modification of the Lich extravesical ureteral approach to perform laparoscopic antireflux surgery. All mini-pigs underwent successful unilateral mobilization, creation of a bladder wall trough and creation of a new ureteral tunnel laparoscopically. Examinations were performed postoperatively, and then serially at 1, 2, 3 and 5 months after repair. Fluoroscopic cystograms demonstrated the resolution of reflux in the corrected ureters and persistence of reflux in the uncorrected control ureters in all animals. Excretory urography showed no evidence of obstruction. Laparoscopic correction of vesicoureteral reflux appears to be technically feasible in the animal model. Long-term followup is necessary to determine the possible applicability of this technique in humans.

Animals↗
PubMed1993

Human fetal compensatory renal growth.

The occurrence of prenatal compensatory renal growth has remained in question, despite the general acceptance of this phenomenon postnatally. We measured by ultrasound imaging the renal length of 22 human fetuses with a solitary kidney or contralateral multicystic dysplastic kidney, and compared it to measurements in 40 normal control fetuses. Renal length was normalized to fetal biparietal diameter. Analysis of covariance showed that the solitary kidneys were significantly larger than normal controls (p < 0.0001), although the rate of growth was not significantly increased above normal. These data document the presence of compensatory renal growth in human fetuses with solitary or functionally solitary kidneys.

Adaptation, Physiological↗
PubMed1993

Laparoscopic pyeloplasty.

A 24-year-old woman presented with symptomatic right ureteropelvic junction obstruction due to anomalous lower pole renal vessels. A dismembered pyeloplasty of the ureteropelvic junction was performed completely laparoscopically.

Adult↗
PubMed1992

The effect of obstruction on the developing bladder.

Congenital bladder obstruction causes significant immediate and long-term consequences yet its pathophysiology remains poorly understood. A model of early fetal bladder obstruction in sheep has been developed to study the response of the developing bladder to high grade obstruction, with particular emphasis on the regulation of growth and development. Congenital bladder obstruction was produced in fetal sheep at 60 days of gestation and studied at 95 days of gestation (14 sheep) or term (12 sheep). A total of 24 age-matched normal sheep served as controls. Bladders were analyzed by total weight, stereological estimation of smooth muscle cell size, number and total mass, deoxyribonucleic acid concentration, muscarinic cholinergic receptor density, myosin isoform analysis and/or passive cystometrics. Congenital bladder obstruction caused a 4.6 times increase in bladder weight at term reflecting a 5.8 times increase in smooth muscle mass. This increase was predominantly that of cellular hypertrophy and less so of hyperplasia, based upon increased cell volume, increased protein-to-deoxyribonucleic acid ratio, and no significant increase in total cell number. Muscarinic cholinergic receptor number per smooth muscle cell increased 3.2 times but it did not change relative to myosin content. The ratio of myosin heavy chain isoforms SM1:SM2 is developmentally regulated and was seen to change from 1.6 at 100 days of gestation to 1.13 at term in normals. After 5 weeks of obstruction SM1:SM2 was 1.27 and it was 1.25 at term, indicating an effect on the developmental regulation of smooth muscle. Rapid fill cystometry in vivo measured the rate of stress relaxation to assess accommodative properties. The half-decay time was increased in all 3 obstructed bladders tested to greater than 15 seconds at 50% capacity (normal less than 5 seconds), suggesting reduced compliance. This study shows that an in utero model of bladder obstruction is feasible. Congenital bladder obstruction produces a variety of structural, biochemical and functional changes in the developing bladder indicative of alterations in the regulation of growth and differentiation.

Actins↗
PubMed1992

The response of the fetal kidney to obstruction.

In a fetal ovine model the renal effects of different anatomic levels of fetal urinary obstruction were studied. Parameters of prenatal renal growth and differentiation were characterized and correlated with the patterns of renal response to in utero obstruction. Complete ureteral or urethral obstruction was produced in the sheep fetus at 55 to 60 days of gestation. Animals were delivered and sacrificed at near term (140 days), and the kidneys were removed and prepared for analysis. Parameters examined included weight, histology, glomerular number and total surface area, as well as urinary sodium, creatinine, osmolarity and N-acetyl glucosaminidase. Three patterns of response were identified, producing hydronephrotic, cystic or dysgenetic kidneys. Hydronephrotic kidneys were usually the result of bladder outlet obstruction or ureteral obstruction with spontaneous urinary decompression. These kidneys were large (20.7 gm. versus normal 10.8 gm., p less than 0.0001), with thinning of cortical parenchyma that was structurally intact. Glomerular number and surface area were normal. Cystic kidneys were large (14.2 gm., p less than 0.05) with grossly visible cysts and an effaced medulla. Cortical structure was distorted by cysts but basic elements were intact. Glomerular number and surface area were not reduced. Dysgenetic kidneys were small (3.9 gm., p less than 0.0001) with markedly abnormal cortical structure and little recognizable medulla. Histological elements similar to fetal structures were present, including cuboidal/columnar tubular epithelium and peritubular mesenchymal collars. Glomerular number and surface area were significantly less than normal (p less than 0.001). The kidneys contralateral to unilaterally obstructed kidneys were significantly larger than normal (16.2 gm., p less than 0.0001), with normal histology, glomerular number and surface area, indicating in utero contralateral renal hypertrophy. Urinary sodium was variably affected in the hydronephrotic kidneys and was identical to plasma in the dysgenetic kidneys. These results indicate the technical feasibility of in utero models of urinary obstruction. Renal growth and patterns of differentiation were markedly affected by in utero obstruction. They should be a major focus in the investigation of congenital obstructive uropathy, since normal processes of renal growth and differentiation form the basis for postnatal function.

Animals↗
PubMed1992

Late onset severe oligohydramnios associated with genitourinary abnormalities.

We evaluated the diagnosis, gestational age at presentation, timing and mode of delivery, and ultimate outcome in those fetuses with third trimester onset of severe oligohydramnios who also had urinary tract abnormalities. A total of 8 fetuses with obstructive uropathy or cystic renal disease was seen during a 2-year period with the onset of severe oligohydramnios noted between 27 and 33 weeks. Immediate and late postnatal pulmonary function was excellent in 5 of the 8 subjects. Three neonates had respiratory distress but only 1 died at birth. Ultimate renal function varied in the 7 survivors. Those with supravesical obstructive uropathy achieved a normal serum creatinine, while the neonates with renal cystic disease and infravesical obstruction did not.

Female↗
PubMed1992

Formation of urothelial structures in vivo from dissociated cells attached to biodegradable polymer scaffolds in vitro.

The use of autologous urothelium would be advantageous for urothelial replacement in many genitourinary reconstructive procedures. Urothelial tissue grafts might be created using isolated populations of transitional epithelium or tissue in concert with an appropriate synthetic substrate. We describe the results of experiments designed to determine the feasibility of using biodegradable polymers as delivery vehicles for the creation of new urothelial structures in vivo from dissociated cells. Primary cultures enriched in uroepithelial cells were obtained from New Zealand white rabbits using a new technique of cell harvest. Cells were seeded onto nonwoven meshes of polyglycolic acid polymers in culture and, after 1 to 4 days in vitro, the cell-polymer scaffolds were implanted into the mesentery, omentum or retroperitoneum of athymic mice. Polymers implanted without cells served as controls. Animals were sacrificed at 5, 10, 20 and 30 days after implantation and 75 implants were examined histologically. Ten days after implantation isolated single cell layers were seen lining the polymer fibers. At 20 and 30 days polymer degradation was evident and urothelial cells lined the polymer in continuous layers of 1 to 3-cell thickness. Anticytokeratin western blots demonstrated the presence of a urothelium-associated cytokeratin in cell-polymer implants recovered after 30 days. These results demonstrate that urothelial cells can be successfully harvested, survive in culture and attach to artificial biodegradable polymers. The urothelial-polymer scaffolds can be implanted into host animals and the implanted cells can achieve spatial orientation as the polymer undergoes biodegradation. These findings suggest that it may be possible to use autologous urothelium, reconfigured on a synthetic substrate, in reconstructive procedures involving the ureter, bladder and urethra.

Animals↗