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Biomedical subjects

C A Peters

Publications and source records attributed to C A Peters.

At least 109 records · Page 6Linked to original sources
PubMed1992

Endoscopic treatment of vesicoureteral reflux with a self-detachable balloon system.

There is controversy about the use of polytetrafluoroethylene (Teflon) paste in children for the endoscopic treatment of vesicoureteral reflux due to evidence of particle migration. However, there are definite advantages in treating patients endoscopically. It is evident that the ideal substance should be able to be delivered endoscopically, conserve its volume, and be nonmigratory and nonantigenic. Towards this goal we developed a catheter with an inflatable, detachable and self-sealing silicone balloon that would fit through a 19 gauge cystoscopic needle. Hydroxy-ethyl-methyl acrylate, a hydrophilic polymer that solidifies within 60 minutes after the addition of ferrous sulfate, was chosen as the filling material for the balloon. Conceptually, the sealed balloon would prevent the migration of hydroxy-ethyl-methyl acrylate and the solidified polymer would prevent volume loss. To test this system reflux was created in 6 Hanford mini-pigs by unroofing the ureters bilaterally. In 2 pigs a previously described method of open surgery was used and in the other 4 reflux was created endoscopically using the resectoscope and laparoscopic scissors. The presence of bilateral reflux was confirmed 4 weeks later with a cystogram and the balloon was implanted unilaterally through a cystoscope. The opposite ureter served as an internal control in all animals. A repeat cystogram was performed 2 to 4 weeks after implantation, demonstrating resolution of reflux in the treated side and persistence of reflux in the opposite untreated ureter. Serial cystograms, ultrasound and excretory urography showed no reflux on the implanted side nor any evidence of obstruction. Tissue sections from various organs showed no evidence of particle migration, granuloma formation or inflammatory reaction. Short-term results show that the balloon implants are able to correct reflux without evidence of obstruction.

Animals↗
PubMed1992

Prenatal diagnosis of the megacystis-megaureter association.

A total of 11 male neonates with hydronephrosis and a large bladder in utero had the megacystis-megaureter association. Prenatal ultrasound findings included bilateral hydroureteronephrosis; a large, smooth, thin-walled bladder, and normal volume of amniotic fluid. Postnatal studies demonstrated grades 4 to 5 bilateral reflux, a large bladder without obstruction and in 2 infants nonfunction of a kidney or renal moiety. Of 7 infants initially managed nonoperatively 5 have undergone surgery due to persistent reflux or breakthrough urinary infections. The prenatal diagnosis of the megacystis-megaureter association can be suspected with reasonable accuracy. Prompt postnatal continuous antibiotic prophylaxis and uroradiological confirmation allow for nonemergency management of this condition with excellent results.

Female↗
PubMed1991

Effect of reversible androgen deprivation on hemoglobin and serum immunoreactive erythropoietin in men.

To examine the role of testosterone in the maintenance of hemoglobin levels, we studied the effect of reversible androgen deprivation on hemoglobin, serum immunoreactive erythropoietin, and serum testosterone in seven men treated with a luteinizing hormone-releasing factor (LHRH) agonist for 6 months and then followed for an additional 6 months. The mean serum testosterone level was 4.35 +/- 1.05 ng/ml initially and it decreased to castrate levels in all patients by 6 months. After stopping therapy, there was a rapid increase in serum testosterone such that by 12 months the mean concentration was normal. The pretreatment hemoglobin was 15.2 +/- 0.9 g/dl (mean +/- SD); after 6 months of androgen deprivation it had fallen to 14.1 +/- 0.4 g/dl (P less than 0.05). Six months after stopping therapy, the hemoglobin rose to pre-treatment levels. Before treatment, serum immunoreactive erythropoietin was 9.5 +/- 4.6 mu/ml (mean +/- SD) and did not change significantly during or after the 6 month period of androgen deprivation. No significant inhibition of burst-forming unit-erythroid (BFU-E) or colony-forming unit-granulocyte macrophage (CFU-GM) was observed at the serum level of nafarelin acetate obtainable in vivo. These data suggest that, within the normal range of hemoglobin in men, androgens are a determinant of the red cell mass.

Aged↗
PubMed1991

The role of the kidney in lung growth and maturation in the setting of obstructive uropathy and oligohydramnios.

The contribution of the kidneys to lung development, which includes growth and maturation, is uncertain but it appears to be complex. Obstructive uropathy with oligohydramnios produces pulmonary hypoplasia characterized by small lungs (decreased lung volume/body weight) and retarded maturation (reduced total airspace). Lung growth and maturation were studied in a model of early gestation obstructive uropathy to understand better their relationship and their prenatal regulation. Of 26 fetal sheep studied at near term (135 days of gestation) 9 had bladder obstruction created at 60 days of gestation, 11 had bladder obstruction at 60 days with in utero decompression at 95 days, and 6 served as controls and shams. Amniotic fluid volume was measured, kidneys were prepared and evaluated histologically, lungs were inflation-fixed and volumes were measured, and airspace volume percentage was measured morphometrically. Experimental and serendipitous variations in the condition of the kidneys and amniotic fluid at delivery permitted an analysis of the contribution of the kidneys and the amniotic fluid to lung growth and maturation. Impairment of growth and maturation was dissociated in certain animals, and this dissociation was referable to the histological status of the kidneys and the presence or absence of amniotic fluid at delivery. Growth was normal when amniotic fluid was present or likely to have been present in late gestation, even with structurally damaged kidneys. With severe renal damage amniotic fluid was not restored even with in utero decompression and it resulted in severely impaired lung growth. Maturation was normal only in the presence of amniotic fluid and intact kidneys. The dissociation of lung growth and structural maturity suggests their independent regulation. The data suggest that the kidneys are important in early lung growth, while the presence of amniotic fluid contributes to growth later in gestation. Lung maturity requires both factors, suggesting a primary kidney contribution with the amniotic fluid acting in a permissive or supportive role.

Amniotic Fluid↗
PubMed1991

Urinary levels of renal tubular enzyme N-acetyl-beta-D-glucosaminidase in relation to grade of vesicoureteral reflux.

Elevated urinary levels of the renal tubular enzyme N-acetyl-beta-D-glucosaminidase (NAG) have been shown to be associated with tubular damage. To determine whether urinary levels of NAG would be abnormal and/or vary with the severity of vesicoureteral reflux, bladder urine was obtained from 31 children without reflux and 32 children with various grades of reflux. Nonrefluxing controls were obtained from children undergoing evaluation for a history of infection, hematuria or voiding abnormality. Patients with evidence of obstruction, neuropathic bladder dysfunction, urinary tract infection or renal failure were excluded. Bladder (32 cases) and ureteral (5 cases) urine from children with reflux was obtained at cystography or at antireflux surgery. Control and reflux patients were not significantly different with regard to sex or age. The mean urinary NAG level in nonrefluxing control patients was 10.63 IU/mg. (range 0.94 to 26.61, standard error of mean 0.43). Mean urinary NAG for all patients with reflux was 16.47 IU/mg. (range 2.85 to 52.02, standard error of mean 0.9). Two children with intrarenal reflux had urinary NAG levels of 52 and 48 IU/mg. Urinary NAG levels are elevated with higher grades of reflux and this relatively simple assay may have clinical usefulness in the assessment of tubular dysfunction associated with reflux.

Acetylglucosaminidase↗
PubMed1991

Effect of in utero vesicostomy on pulmonary hypoplasia in the fetal lamb with bladder outlet obstruction and oligohydramnios: a morphometric analysis.

A model of early gestation bladder outlet obstruction and oligohydramnios in the fetal lamb is characterized by small, immature lungs (pulmonary hypoplasia). The current study examines how in utero relief of urinary tract obstruction produced early in gestation modifies pulmonary hypoplasia. Bladder obstruction was created at 60 days gestation in fetal sheep (term = 140 days); 11 fetuses then underwent in utero decompression at 95 to 100 days; six were left obstructed. Five normal fetuses served as controls and two underwent sham obstruction and vesicostomy. All were delivered and sacrificed near term (135 days), the right lung was inflation-fixed and its volume determined. Relative volumes of alveoli, alveolar ducts, and tissue, alveolar surface area, and alveolar numerical density were estimated morphometrically. Kidneys were examined histologically. In all animals persistent bladder obstruction produced oligohydramnios. Bladder obstruction to term produced pulmonary hypoplasia with a mean right lung volume-to-body weight ratio (LV:BW) of 14.3 cc./kg. (normal = 36.4, p less than 0.001). Structural immaturity was evidenced by an airspace fraction of only 57% (normal = 68%, p less than 0.05). Kidneys in these animals were not dysplastic; there was hydronephrosis or evidence of spontaneous urinary decompression. In eight of the 11 animals, decompression improved the LV:BW ratio to 28.4 cc./kg. (vs. obstructed, p less than 0.001; vs normal, p less than 0.05) and normalized maturity. All had increased amniotic fluid at delivery; kidneys in 7/8 animals were normal, and the other had moderate hydronephrosis. One of the 11 animals had normal kidneys, oligohydramnios, immature lungs, but with normal volume. Oligohydramnios was present in the other two of 11 fetuses despite successful decompression and they had markedly dysmorphic kidneys and profoundly hypoplastic and immature lungs (LV:BW 5.1 cc./kg.). Even after 35 days (25% gestation) of obstruction, in utero urinary tract decompression permits better lung growth and maturation than in persistently obstructed animals. The degree of renal damage from obstruction appears to be a critical determinant in the correction of pulmonary hypoplasia.

Animals↗
PubMed1991

Endoscopic injection of glutaraldehyde cross-linked bovine dermal collagen for correction of vesicoureteral reflux.

From November 1986 through May 1989, a Food and Drug Administration approved investigational study was done to assess the safety and efficacy of glutaraldehyde cross-linked bovine dermal collagen in the endoscopic treatment of vesicoureteral reflux. Over-all, 57 patients (92 ureters) were treated. The majority of ureters (68.5%) had grade II to III/V vesicoureteral reflux (international classification). One treatment was given in 61.4% of the patients, while 33.3% required 2 and 5.3% required 3 treatments. Nonduplicated/primarily refluxing ureters comprised 68.5% of the total, while 13% were duplex/primarily refluxing and 18.5% were surgical failures. The procedures were performed on an outpatient basis in all but 3 patients. Patients were evaluated by voiding cystourethrogram and renal/bladder sonography before and after treatment at 1 month and 1 year. Cure at 1 month after the last treatment was achieved in 75% of the ureters. Among the ureters cured at 1 month the cure persisted in 79% at 1 year after treatment. Cure at 1 year was achieved in 65% of all ureters evaluated, regardless of the status at 1 month. Procedure-related morbidity was minimal and there were no adverse reactions to the implant substance. Thus, glutaraldehyde cross-linked bovine dermal collagen appears to be safe and effective in the endoscopic treatment of vesicoureteral reflux.

Animals↗
PubMed1991

Structural genitourinary defects detected in utero.

Fetal genitourinary anomalies are detected with increasing frequency due to the large numbers of fetuses that undergo screening ultrasonography (US) for nonspecific indications. One hundred seventy-seven patients were evaluated for fetal urinary abnormalities over a 2-year period. Fetal hydronephrosis accounted for 154 (87%) of the cases, with the remaining diagnoses including multicystic dysplastic kidney, autosomal recessive polycystic kidney disease, and renal agenesis or hypodysplasia. Ureteropelvic junction obstruction was the most common postnatal anatomic abnormality (29%), with a large number of cases of prenatally diagnosed hydronephrosis resolving either prenatally (33%) or postnatally (24%). Prenatal US findings were retrospectively analyzed with regard to the degree of hydronephrosis at different stages of gestation. Data showed that there is a gradual rise in anteroposterior renal pelvic diameter during gestation and that there is a correlation between this diameter and the ultimate renal outcome in regard to surgical repair. This information can provide guidance in making recommendations to parents and physicians.

Congenital Abnormalities↗
PubMed1990

The urodynamic consequences of posterior urethral valves.

We evaluated urodynamically 41 patients with posterior urethral valves because of signs or symptoms of incontinence (35), frequency (3), hydronephrosis (2) and infection (1). Findings included normal urodynamic evaluations in 3 patients, 2 had high voiding pressures secondary to outlet resistance and 1 had incontinence on the basis of external urethral sphincter damage. In the remainder 3 patterns of bladder dysfunction were identified. Myogenic failure with overflow incontinence occurred in 14 patients. In this group clean intermittent catheterization or Valsalva's voiding was used for emptying. Hyperreflexic bladders were seen in 10 patients. Pharmacological suppression of instability was effective in 5 of 7 patients treated; 1 required bladder augmentation. Eleven children had a small capacity bladder and poor compliance. Post-void residuals were low and these bladders were generally but not always stable. Pharmacological bladder relaxation was successful in 3 patients, 3 underwent augmentation, 1 did well with alpha-agonists and followup is unavailable on the other 4. These 3 patterns of bladder dysfunction represent an overlapping constellation of residual urodynamic abnormalities due to previous bladder outlet obstruction. Individual patients may show facets of several types of dysfunction associated with 1 predominant pattern.

Child↗
PubMed1990

Flow cytometric evaluation of multicystic dysplastic kidneys.

The most appropriate management of the multicystic dysplastic kidney remains controversial. At issue is the long-term risk of the development of malignancy in the multicystic dysplastic kidney. The association between renal dysplasia and neoplasia has not been confirmed, with only 6 cases of malignancy reported. Nephroblastomatosis, a probable precursor of Wilms tumor, has been found in 5 to 7% of the cases of multicystic dysplastic kidney when specifically sought. In an attempt to determine whether a relationship exists between renal dysplasia and neoplasia in terms of abnormalities of cellular deoxyribonucleic acid content we performed flow cytometric evaluation on 30 formalin fixed, paraffin embedded archival specimens of multicystic dysplastic kidneys. None of the kidneys had evidence of malignancy. Nuclear deoxyribonucleic acid ploidy studies were performed on single dissociated nuclei prepared by the technique of McLemore and associates and stained with propidium iodide. All specimens demonstrated a diploid pattern of deoxyribonucleic acid, including 3 specimens with nephroblastomatosis or extensive papillary growth, and no specimen demonstrated a tetraploid or aneuploid pattern. The mean G0/G1 fraction was 85.94% (standard deviation 4.59) and the mean S/G2/M fraction was 12.54% (standard deviation 4.72). These findings do not support or negate the potential for neoplasm associated with multicystic dysplastic kidney, since a diploid deoxyribonucleic acid pattern does not eliminate the possibility of the future development of malignancy.

DNA↗
PubMed1990

Current concepts in the perinatal diagnosis and management of hydronephrosis.

Perinatal urology has become a significant facet of pediatric urologic practice. This article reviews the approaches to the diagnosis of prenatal hydronephrosis and its typical sonographic appearances in relation to the underlying pathology. A review of the outcomes of prenatal uropathology serves as a basis on which to interpret reports of prenatal intervention for hydronephrosis. A critical review of the experience of prenatal intervention is conditionally supportive of its benefits, but this view must be tempered by a recognition of the inherent risk to the mother and fetus. Included within this view is a recognition that not all hydronephrosis is caused by obstruction. More specific prognostic indicators of renal and pulmonary functional reserve are critically needed to permit appropriate patient selection. This must be coupled with more rigorous assessment of outcomes and complete reporting of the results. Continued basic and clinical research is important in developing these data. A management strategy for hydronephrosis in the prenatal and postnatal periods is presented, based on the goal of permitting maximal renal as well as pulmonary development in utero and in the newborn period.

Ethics, Medical↗
PubMed1990

Experimental congenital obstructive uropathy.

Continued experimental work in congenital obstructive uropathy is essential to support the rapidly advancing field of fetal medicine. It is possible to reproduce the clinically relevant obstructive lesions in an experimental model. On the basis of data from these models, the tentative conclusion is that in utero intervention is beneficial in severe congenital obstructive uropathy associated with oligohydramnios. The limited human experience provides insufficient data to confirm this hypothesis but has demonstrated the technical feasibility of prenatal interventions. There is a critical need for further refinement in understanding the complex pathophysiology of congenital obstructive uropathy, not only the renal consequences, but also the pulmonary and systemic effects. There remains the particular need to resolve the determinants and indicators of functional salvageability of the kidneys and lungs in congenital obstructive uropathy.

Animals↗
PubMed1990

Barium and antimony distributions on the hands of nonshooters.

Barium and antimony levels from selected areas of the left and right hands of 269 nonshooters provide a database for interpretation of gunshot residue swab analysis results. The database represents a variety of activities of individuals sampled by collectors throughout the United States. Nonshooting exposure to barium and antimony can generally be distinguished from firearms-associated exposure by considering the relative levels of the elements, location on the hands, and condition of the swabs. Consistent definition of sampling procedures and accurate analytical results make this database applicable for interpretation of data generated by most gunshot residue swab examiners.

Antimony↗
PubMed1990

Splitting the pubis for exposure in difficult reconstructions for incontinence.

We have presented our technique for and experience with splitting the symphysis to provide wide exposure in reconstructive surgery for incontinence. Our experience has demonstrated that the technique is widely applicable to many reconstructive situations in patients of all ages. We believe that spreading the pubic symphysis provides access to the urethra and bladder neck not otherwise possible and regard it as an important factor in the success of many difficult operations to correct incontinence. Although seemingly a radical maneuver, it did not cause complications in any of 51 cases.

Child↗
PubMed1990

Evaluation and management of urinary incontinence after surgery for posterior urethral valves.

Posterior urethral valves lead to an overlapping constellation of urodynamic abnormalities, often many years after the initial diagnosis and valve ablation. Voiding dysfunction and urinary incontinence in boys with a history of valves are seldom the result of sphincteric incompetence. Three major categories of bladder dysfunction may cause voiding symptoms: myogenic failure, detrusor hyperreflexia, and bladder hypertonia. The interaction of the severity and duration of valve obstruction may be important factors, but the determinants of ultimate bladder function in the setting of urethral valves remain unclear. A careful urodynamic assessment is needed to define the abnormal bladder and to select and evaluate therapy. Therapy should be designed to provide low-pressure urinary storage for a socially acceptable period of time as well as complete emptying of the bladder. Success may require several lines of treatment and demands patience, not only of the patient and his family, but of the physician.

Child↗