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Biomedical subjects

B A Kogan

Publications and source records attributed to B A Kogan.

At least 91 records · Page 5Linked to original sources
PubMed1990

Fetal bladder histology in posterior urethral valves and the prune belly syndrome.

Bladder histology was reviewed in fetuses with posterior urethral valves and the prune belly syndrome, and compared with that of controls. Fetuses with posterior urethral valves had increased muscle thickness (1.7 +/- 0.3 versus 0.9 +/- 0.2 mm.) and a slightly increased ratio of connective tissue (38 +/- 6 versus 31 +/- 7%). Those with the prune belly syndrome fell into 2 groups: 1 had anatomical evidence of obstruction, increased muscle thickness and a normal ratio of connective tissue (2.2 +/- 0.6 mm. and 28 +/- 9%), while 1 had no evidence of obstruction and thin bladders with increased connective tissue (0.8 +/- 0.4 mm. and 45 +/- 12%). These results suggest that the phenotypic appearance of the prune belly syndrome may result from either a mesenchymal defect or urinary tract obstruction.

Connective Tissue↗
PubMed1990

Monitoring renal function in children with urological abnormalities.

In clinical practice glomerular filtration rate routinely is estimated by measuring serum creatinine and using the Schwartz formula for calculating an estimate of creatinine clearance or using the Gates formula for calculating the clearance of diethylenetriaminepentaacetic acid based on the uptake during radionuclide imaging. We compared these methods to the plasma clearance of iothalamate during extended constant infusion. All 3 tests were performed in 14 boys and 5 girls 9 months to 16 years old with urological abnormalities and moderate renal insufficiency. Using iothalamate as the reference, calculated creatinine clearance overestimated glomerular filtration rate by more than 20% in 12 of the 19 patients (63%). Diethylenetriaminepentaacetic acid uptake grossly overestimated glomerular filtration rate; in only 3 instances was the estimate within 20%. The accuracy of both formulas was better in older patients and in those with more normal renal function. We conclude that the Gates formula for measuring glomerular filtration rate is grossly inaccurate in children with diminished renal function and the Schwartz formula, although better, has a poor level of predictability.

Adolescent↗
PubMed1990

Neuroprostheses in the management of incontinence in myelomeningocele patients.

A 16-year-old boy and a 17-year-old girl underwent successful closure of the meningomyelocele defect in childhood but they continued to suffer incontinence of stool and urine. After a 5-day trial with percutaneous electrostimulation of the pudendal nerve both patients received permanent neuroprosthetic implants. They became completely continent of stool and exhibited greater than 90% improvement in urinary control. These patients demonstrate that there is a small subset of meningomyelocele patients who, despite absence of spontaneous reflex tonus in the urinary and bowel sphincters, nevertheless have preserved motor capabilities.

Adolescent↗
PubMed1990

Bladder function in patients with lipomyelomeningocele.

We evaluated preoperative and postoperative bladder function in 31 consecutive patients who underwent definitive operative correction of lipomyelomeningocele. Of 12 patients less than 1.5 years old at operation, bladder function was normal preoperatively and postoperatively in 5 (42%) and normalized postoperatively in 4 (33%). In 5 patients (42%) abnormal urodynamic findings were the only sign of neurological abnormality. Of the 19 patients older than 1.5 years at operation bladder function was normal preoperatively and postoperatively in only 4 (21%), and normalized postoperatively in none. We conclude that the majority of patients with lipomyelomeningocele have bladder dysfunction, and that in some cases this dysfunction can be prevented and/or reversed by early neurosurgical intervention. Urodynamic assessment is helpful as part of the neurological evaluation and in directing patient care.

Adolescent↗
PubMed1990

Treatment of infants with neurogenic bladder dysfunction using anticholinergic drugs and intermittent catheterisation.

The use of anticholinergic drugs in infants with neurogenic dysfunction has not been well documented. In this study, 35 neonates at risk of upper urinary tract damage from neurogenic dysfunction were treated from infancy with anticholinergics, in combination with clean intermittent catheterisation. None of the patients showed upper urinary tract deterioration with follow-up ranging from 6 to 72 months, although 2 required vesicostomy--1 due to difficulty with catheterisation and 1 due to possible anticholinergic side effects. Only 2 (6%) have had clinical pyelonephritis. Twenty-five (76%) are virtually dry between catheterisation. We conclude that anticholinergics are safe and effective, even in the neonatal period, when used in combination with clean intermittent catheterisation for the treatment of neonates with neurogenic bladder dysfunction.

Combined Modality Therapy↗
PubMed1989

Lower urinary tract function in the sheep fetus: studies of autonomic control and pharmacologic responses of the fetal bladder.

An experimental preparation was developed to study fetal bladder function. In 16 fetal sheep at 120 days' gestation, two distinct types of bladder contractions were identified, one typical of contractions seen after birth and one phasic. Bladder capacity and intravesical pressure during contraction varied widely among fetuses, but residual urine was invariably less than one ml. Several drugs altered fetal bladder function: bethanechol decreased bladder capacity (6.8 vs. 13.6 ml.); atropine increased bladder capacity (27.3 vs. 6.8 ml.) and resulted in a 17-ml. residual urine; and ritodrine, magnesium sulfate and diltiazem inhibited bladder contractions and also resulted in residual urines of seven, six and seven ml. respectively. The fetal sheep bladder at 120 days' gestation is under both cholinergic and beta-adrenergic control. Further, drugs currently administered to pregnant women for the treatment of pre-term labor and pre-eclampsia cross the placenta and can directly alter bladder function in the developing fetus and the neonate.

Animals↗
PubMed1989

P-31 MR spectroscopy in assessing testicular torsion: rat model.

To develop phosphorus-31 magnetic resonance (MR) spectroscopy as an indicator of testicular viability, unilateral 720 degrees torsion of the spermatic cord was performed in 11 Copenhagen rats. In six of 11 rats, detorsion was done 1 hour later. The authors used special surface coils to obtain P-31 MR spectra (at 2 T) from both tests, then correlated MR findings with those from gross morphologic and histologic examination. In the normal testis, P-31 MR spectra had prominent phosphomonoester (PME) and adenosinetriphosphate (ATP) peaks. Testicular torsion dramatically reduced ATP to almost undetectable levels and significantly decreased the PME/Pi at 1 hour (1.18 +/- 0.22) in nine rats. In two rats, however, no spectral changes were present. Of the six rats in which detorsion was performed, three showed immediate regeneration of ATP and a normal PME/Pi (2.87 +/- 0.06) 3 hours later; testicles in the other three rats did not recover (PME/Pi = 0.72 +/- 0.01). Because gross morphologic observations and histologic findings prior to detorsion were unable to differentiate viable from nonviable tests, these preliminary data suggest P-31 MR spectroscopy may help clinicians diagnose testicular torsion and assess testicular viability.

Animals↗
PubMed1988

Testicular histology in fetuses with the prune belly syndrome and posterior urethral valves.

Intra-abdominal cryptorchidism and infertility are universal features of the prune belly syndrome but they usually are not seen with posterior urethral valves. To understand further the differences between these patients we reviewed testicular histology in 5 fetuses from each of 3 groups: prune belly syndrome, posterior urethral valves and normals. Spermatogonia were noted in all but the numbers were significantly reduced in those with the prune belly syndrome and posterior urethral valves compared to normals: 8.6 and 13.4 versus 31.2 per 10 high power fields, respectively. The fetuses with the prune belly syndrome also had marked Leydig cell hyperplasia in contrast to the other groups. These findings suggest that the testicular pathological condition in patients with the prune belly syndrome is caused by more than mechanical cryptorchidism.

Fetus↗
PubMed1988

Old and new aspects of testicular torsion.

Torsion of the spermatic cord is a common condition that requires emergent treatment. Diagnosis based on history and physical examination is rarely conclusive and, although a number of radiographic studies can be helpful, any clinically suspicious lesion should be treated immediately. Manual detorsion may be helpful, but operative exploration with bilateral orchiopexy is still essential. Prolonged torsion usually results in unilateral testicular atrophy and, in postpubertal animals, an autoimmune injury with consequent contralateral testicular damage is seen. This suggests that, in humans, necrotic and perhaps marginal testes should be removed. In addition, subfertility after unilateral torsion may be due to a preexisting abnormality in both testes. Nonetheless, the cornerstone of management remains rapid detorsion and bilateral fixation to prevent future torsion.

Emergencies↗
PubMed1987

Ontogeny of gonadotropin secretion in congenital anorchism: sexual dimorphism versus syndrome of gonadal dysgenesis and diagnostic considerations.

The hormonal characteristics of anorchism are elevated basal levels of gonadotropins, especially follicle-stimulating hormone and a low concentration of plasma testosterone that fails to increase after the administration of human chorionic gonadotropin. However, little is known about the dynamics of plasma gonadotropin secretion in infants and children with anorchism. We analyzed plasma gonadotropin concentrations and their responses to luteinizing hormone releasing factor, along with plasma testosterone responses to human chorionic gonadotropin, in 9 children with surgically proved bilateral anorchism. Basal concentrations of gonadotropins, especially plasma follicle-stimulating hormone, are elevated above normal during the first 3 to 4 years of life, decrease gradually to normal prepubertal levels and then increase again after age 9 years. This age-dependent diphasic pattern of gonadotropin secretion is comparable to that described previously in patients with the syndrome of gonadal dysgenesis and it is consistent with steroid-independent central nervous system inhibition of pulsatile luteinizing hormone releasing factor secretion during mid childhood. Moreover, a sex difference in follicle-stimulating hormone and luteinizing hormone values was observed; the mean follicle-stimulating hormone and luteinizing hormone concentrations in anorchid boys less than 3 years old were lower than in patients with Turner's syndrome. We suggest that this sex dichotomy is a consequence, at least in part, of the actions of testosterone derived from the fetal testis on the fetal hypothalamus. Luteinizing hormone releasing factor administration to anorchid male subjects resulted in an age-dependent augmented release of gonadotropin, particularly follicle-stimulating hormone. This study emphasizes that the age of the patient must be considered when interpreting basal gonadotropin levels. We also propose that in mid childhood the luteinizing hormone releasing factor test in conjunction with the human chorionic gonadotropin stimulation test is a more accurate hormonal indicator of patients with congenital anorchism than either the human chorionic gonadotropin test or basal gonadotropin concentrations.

Age Factors↗
PubMed1987

Magnetic resonance imaging in genital anomalies.

Magnetic resonance imaging, a new radiographic modality that is not dependent on ionizing radiation or intravenous contrast agents, was used to identify undescended testes in 11 patients. Of 14 undescended testes 13 were identified and the only testis that was not seen was in a patient with surgically proved unilateral anorchism. We also used magnetic resonance imaging in 9 patients with various types of intersex. The anatomy of the corpora cavernosa, vagina, uterus and gonads was well seen in each instance.

Adolescent↗
PubMed1987

Fertility in cryptorchidism: improved timing of fixation and treatment in an experimental model.

Modifications were made in an experimental model in the rat to make it more analogous to human cryptorchidism and more useful in evaluating treatment. The age of experimental bilateral cryptorchidism was changed from 3 days to 11 days. Neither group was able to father offspring. The age at orchiopexy also was modified from the range of 21 to 28 days to exactly 21 days. The ability to father offspring improved significantly (72 versus 30 per cent) and it was not significantly different from previously reported sham operated rats (84 per cent). The current experimental model demonstrates that early surgical treatment can restore fertility to mechanically cryptorchid animals. The model can be used to evaluate the effects of varying types and timing of treatment.

Age Factors↗
PubMed1987

Fertility in cryptorchidism: further development of an experimental model.

Further development of an experimental model for evaluating fertility in cryptorchidism led to studies of unilateral cryptorchidism, endocrinological cryptorchidism, and the effects of treatment. The results demonstrate that rats with unilateral mechanical cryptorchidism have a significant diminution in the ability to impregnate females (impregnation rate, 45%) when compared with sham-operated controls (84%) and rats undergoing unilateral orchiectomy (88%). In addition, we demonstrated that lower doses of estradiol caused cryptorchidism and resulted in infertility of approximately the same degree as higher doses (impregnation rates, 18% and 0%, respectively), but avoided obvious side effects. Treatment of estradiol-induced cryptorchidism with human chorionic gonadotropin resulted in testicular descent, but did not significantly improve the ability to bear offspring (10% with hCG vs. 0% without). Surgical orchiopexy after surgically induce mechanical cryptorchidism resulted in improved fertility (30% vs. 0%); however, the improvement was still significantly less than the control rate. In summary, this experimental model demonstrates the effects of various aspects of cryptorchidism and its treatment on fertility and can easily be adapted to evaluate important clinical problems.

Animals↗
PubMed1987

Undescended testis: value of MR imaging.

Magnetic resonance (MR) imaging was performed in 32 male patients, 20 with no abnormalities and 12 with clinically suspected undescended testes. The results were compared with ultrasonographic, computed tomographic, clinical, and surgical findings. The undescended testes were unilateral in eight patients (one had testicular duplication) and bilateral in four. Of 16 undescended testes, 15 were correctly identified on MR images. One intraabdominal testis was not seen. Testis-fat contrast at 0.35 T was optimal with a short repetition time (TR) and a short echo time (TE). At 1.5 T, good contrast was achieved with short TR/TE sequences, but the contrast was even more pronounced with even longer TR/TE parameters. In seven patients with unilateral undescended testes, the undescended and contralateral testes showed symmetrical tissue signal intensity on both T1- and T2-weighted images. In three, the undescended testis was of lower signal intensity, suggesting atrophy. MR imaging promises to become an important diagnostic tool in the detection of undescended testes.

Adolescent↗
PubMed1986

Fertility in cryptorchidism: an experimental model.

Because the long-term efficacy of treatment for cryptorchidism is difficult to evaluate in humans, we developed an animal model to study the effects of cryptorchidism on fertility. Sprague-Dawley rats were treated within the first few days of life to create either mechanical or endocrinological cryptorchidism. The ability to father offspring was used as a measure of fertility. Significant differences in fertility between rats with bilateral cryptorchidism and controls were observed, regardless of whether the cause was mechanical or endocrinological. Rats with unilateral cryptorchidism were significantly less fertile than those that underwent unilateral orchiectomy. Further development of this model will permit prospective evaluation of different treatment modalities in cryptorchidism.

Animals↗
PubMed1986

Urological aspects of the tethered cord syndrome.

We performed urological evaluations in 18 patients with the tethered spinal cord syndrome. Of the patients 4 had low grade vesicoureteral reflux but none had significant upper tract anomalies. Urodynamic studies documented a flaccid bladder in 9 patients (5 with supersensitivity to bethanechol), an uninhibited bladder in 5, mixed bladder dysfunction in 2 and normal function in 2. Repeat urodynamic studies were performed in 15 patients at least 6 months after release of the tethering. Of 8 patients with flaccid bladders studied postoperatively 6 had significant changes: 2 became normal, 2 had limited contractions and 2 had evidence of upper motor neuron abnormalities. Supersensitivity to bethanechol was of no predictive value. All 4 patients with uninhibited bladders who were evaluated preoperatively and postoperatively had improved and 3 currently are entirely normal. Careful urological evaluation of patients with the tethered spinal cord syndrome is helpful not only for diagnosis but also for appropriate management preoperatively and postoperatively. The fact that lower urinary tract function improves in some patients should encourage early and aggressive neurosurgical management of patients with this syndrome.

Adolescent↗