Canine tracheal injury by neodymium-YAG laser irradiation.

The relationship between endoscopic graded neodymiumyittrium aluminum garnet (Nd-YAG) laser intensity and the magnitude of effects on the tracheal wall was studied in two mongrel dogs. The dogs were anesthetized and graded Nd-YAG laser burns of 50, 100, and 200 Joules (J) were produced on the distal tracheal walls with a laser fiber inserted through a bronchoscope. One dog was killed immediately after injury and the other 24 hours later. At the time of killing, the trachea was excised and prepared for light microscopic (LM) and scanning electron microscopic (SEM) examination. We found that the injury produced by the 50 J intensity beam was confined to the mucosa and submucosa, with no destruction of the tracheal cartilage; by contrast, transmural penetration of the trachea was observed at intensities of 100 and 200 J. These results indicate that a strong correlation exists between laser intensity and the magnitude of the resulting tracheal injury. We suggest that the intensity of a Nd-YAG laser, endoscopically directed perpendicular to the tracheal wall, should not exceed 50 J in order to minimize the risk of perforating the tracheal wall.

Effects of sulfur dioxide on pore populations of canine tracheal epithelium.

The bioelectric and barrier properties of the tracheal epithelium in nose-breathing dogs and in dogs that had been exposed for 75 min to compressed air or to two high concentrations of SO2 were measured and compared. We also studied tissues that had been treated with chloroform. Based on a model of restrictive diffusion we demonstrated heteropores (6 and 250 A) in the control tissues. Bioelectric changes due to 100-ppm SO2 were minimal. After exposure to 500 ppm SO2, adverse changes in the bioelectric properties were focal; they were marked in 8 out of 12 animals but were less striking in the other 4. Nonelectrolyte permeability increased with an increase in SO2 concentrations. Small pores were still present in the tissues severely affected by SO2 but they were absent in chloroform-treated tissues. Scanning electron microscopy of tissues from animals exposed to 500 ppm SO2 showed that in the same dog tissue appearance varied from normal to one of repair (normal bioelectric properties) or one of marked exfoliation of ciliated cells (abnormal bioelectric measurements).

Histamine dose-response curves in guinea pigs.

Histamine dose-response curves were performed on anesthetized tracheostomized guinea pigs that were paralyzed and mechanically ventilated at a constant tidal volume and breathing frequency. The dose was calculated by generating an aerosol of known concentration and measuring the volume delivered to the lung. Increasing the dose was accomplished by increasing the number of breaths of aerosol delivered. The response to each dose was determined by measuring the change in airway resistance (RL) and dynamic compliance (Cdyn) using the method of Von Neergaard and Wirz (Z. Klin. Med. 105: 51-82, 1927). With increasing doses of histamine, RL increased and reached a plateau at approximately five times the base-line value and Cdyn fell to approximately 20% of its initial value. The variability in the base-line and maximum response as well as the calculated sensitivity and reactivity was less than that previously reported. Propranolol pretreatment increased resting RL and shifted the dose-response curve for RL to the left of the controls, increasing reactivity but not sensitivity. Atropine shifted the dose-response curve to the right of the control, decreasing sensitivity but without changing reactivity. The data for Cdyn showed that atropine pretreatment caused a higher resting value and propranolol pretreatment a lower value at the highest histamine dose but no differences in either sensitivity or reactivity.

Neonatal capsaicin treatment alters basal pulmonary mechanics and response to methacholine in F344 rats.

Full methacholine dose-response curves were performed on anesthetized tracheostomized Fischer 344 adult rats treated neonatally with capsaicin (50 mg/kg) or with vehicle alone. Capsaicin, the hot extract of pepper, releases substance P (SP) from nonmyelinated sensory nerve endings and causes acute bronchoconstriction and airway microvascular leakiness. Chronic treatment with capsaicin leads to depletion of SP and other tachykinins from afferent C-fibers and can therefore be used as a tool to investigate the contribution of SP innervation to airway responses. The rats (9 controls and 6 treated with capsaicin) were paralyzed with succinylcholine and mechanically ventilated at a constant tidal volume and frequency. Airway resistance (RL) and dynamic compliance (Cdyn) were determined at each dose of methacholine from measurements of volume, flow, and transpulmonary pressure. Capsaicin-treated rats were found to have a significantly reduced baseline RL [0.150 +/- 0.039 (SD) vs. 0.225 +/- 0.050 cmH2O.ml-1.s, P = 0.009] and a correspondingly significantly elevated Cdyn (0.371 +/- 0.084 vs. 0.268 +/- 0.053 ml/cmH2O, P = 0.012). There was no significant difference in sensitivity to methacholine, but the maximal response to methacholine was significantly greater in the capsaicin-treated rats. In terms of RL, the maximal response for capsaicin-treated rats was 6.03 x baseline +/- 0.98 vs. 4.30 x baseline +/- 1.80 (P = 0.05) for controls, and for Cdyn changes the maximal decrease was 5.75 x baseline +/- 1.22 vs. 3.83 +/- 0.69 (P = 0.002). The observed differences in RL and Cdyn coupled with the differences in maximal responses can be attributed to the selective destruction of a subpopulation of pulmonary afferent C-fibers.(ABSTRACT TRUNCATED AT 250 WORDS)

Prenatal diagnosis of duplex system hydronephrosis: effect on renal salvage.

OBJECTIVES: To determine if prenatal identification of significant renal duplication anomalies affects the management of the patient or the clinical outcome. METHODS: This is a retrospective review of 79 consecutive children with severe hydronephrosis involving a duplex renal collecting system, identified by either prenatal ultrasound (asymptomatic), or symptoms, most often urinary tract infection, but also including abdominal mass, hematuria, or incontinence. An individualized combination of voiding cystourethrogram, ultrasound, intravenous urogram, and nuclear renal scan was used to assess anatomy and function. Ablation of the involved segment was carried out if no or extremely poor function was identified; a definitive reconstructive procedure was elected in the face of easily measureable function. Outcome was determined clinically and by repeat imaging. RESULTS: There was no difference in the rate of renal segment salvage between the prenatally and clinically diagnosed groups. Of the cases analyzed, 20/79 were prenatally identified, of which 13/20 (65%) were reconstructed; 59/79 were identified on clinical grounds, of which 34/59 (58%) were reconstructed. One patient in the prenatal salvage group underwent removal of the affected kidney 5 years later. Another, in the clinical salvage group, underwent a successful secondary procedure for closure of a ureteral fistula. All others have shown improved function, drainage, or both in follow-up. No secondary procedures have been required for the ablation group to date. Follow-up ranges from 4 months to 12 years. CONCLUSIONS: Prenatal identification of significant duplex system hydronephrosis does not improve the rate of renal segment salvage, as determined by standard radiographic means, compared to later identification on clinical grounds. The decision for reconstruction versus ablation in significant duplex system hydronephrosis can be made on the basis of function alone.

Abdominoscrotal hydrocele in infancy.

Abdominoscrotal hydrocele is an uncommon clinical entity. Fewer than 200 cases have been reported in the literature, only two of which described bilateral involvement. We present five cases of abdominoscrotal hydrocele occurring in infancy, three of which revealed bilateral disease. The first case represents the youngest patient ever reported with this condition and the first reported with secondary bilateral upper tract dilatation. The historical background, pathophysiology, diagnosis, and treatment are reviewed.

Appendiceal abscess masquerading as acute urinary retention in children.

Two boys with acute urinary retention were found to have a persistent pelvic mass after bladder decompression. Evaluation in each disclosed a large pelvic abscess secondary to a ruptured appendix. The diagnosis of appendicitis may be difficult and appendiceal abscess presenting with acute urinary retention in children has been reported previously in only 7 instances. History, physical examination, laboratory studies, and radiographic and ultrasonic evaluations should lead to the correct diagnosis, and surgical intervention restores normal voiding.

Buccal mucosal grafts for urethral reconstruction.

OBJECTIVES: Patients requiring urethral reconstruction but who have a paucity of usable genital tissue present a considerable technical challenge. Herein we report the experience of three centers in the use of buccal mucosa for urethral replacement. METHODS: From 1991 to 1996, 22 urethral reconstructions were completed using a graft of buccal mucosa. Eighteen of 22 patients had previously failed hypospadias repairs, while three had bulbar urethral stricture and one had penile carcinoma. Grafts were taken from either the inner cheek or the lower lip, and seven were used as a combined graft. Onlay grafts were used in 6 cases and tubularized grafts in 16 cases. RESULTS: Two patients developed complications at the donor site. Nine of 22 patients had complications of the urethroplasty-two had meatal stenosis, four developed a urethral fistula, and three developed urethral stricture. All complications have been managed successfully to date. CONCLUSIONS: Buccal mucosa is an excellent source of graft material for urethral replacement in complex urethroplasties. It is readily available, in abundant supply, and has physical properties beneficial to free graft survival.

Hyperreninemic hypertension secondary to radiation nephritis in a child.

Radiation injury to the kidney, first reported almost eighty years ago, may vary from subclinical changes in renal blood flow or enzyme activity to clinically significant hypertension and/or renal failure. A child with radiation-induced hyperreninemic hypertension was cured by nephrectomy. The microscopic, subclinical, and clinical changes of irradiation injury are reviewed. The etiology of radiation-induced hypertension, methods of radioprotection, and early detection of radiation renal damage are discussed.

Intussusception following resection of Wilms tumor.

Postoperative intussusception is a documented complication of pediatric surgical and pediatric urologic abdominal operations. In contrast to "primary" intussusception's triad of crampy abdominal pain, palpable abdominal mass, and "currant jelly" stools, postoperative intussusception is generally characterized by abdominal pain and vomiting. An abdominal mass is not usually palpable, and few children have bloody stools. Proper diagnosis and treatment may be delayed because of similar abdominal symptoms in children who may be receiving radiation and chemotherapy, or with prolonged ileus. Two children operated on for Wilms tumor demonstrate the need for awareness of this potential problem in the postoperative patient.

Acute scrotal swelling.

Acute scrotal swelling is a potential emergency. The differential diagnosis includes torsion of the testis or one of the testicular appendages, hydrocele, varicocele, trauma, tumor, idiopathic scrotal edema, and Henoch-Schönlein purpura. Imaging studies, such as radionuclide scanning and color Doppler ultrasonography, are helpful in equivocal cases.

Observations on the fine structure of the baroreceptors and adrenergic innervation of the guinea-pig carotid sinus.

We examined the fine structure of the baroreceptors and the adrenergic innervation of the guinea-pig carotid sinus. The tunica adventitia contained many nerve bundles whose perineuria enclosed unmyelinated nerve fibers, alone or together with myelinated nerve fibers. Baroreceptors, which lay close to elastic and collagen fibers in the adventitia and media, were surrounded by "terminal" cells with ultrastructural features characteristic of Schwann cells and contained inclusions of various types. Morphologic features of the baroreceptors included densely packed mitochondria, osmiophilic lamellated and homogeneous bodies, clear and granular vesicles, lamellar systems, glycogen granules, neurofilaments, neurotubuli, and vacuolated mitochondria. In animals that had been treated with 6-hydroxydopamine, occasional electron-dense endings (or fibers) were observed in the adventitial layer. The baroreceptors in the guinea-pig carotid sinus appear to have most of the morphologic features reported for other species.

Prenatal sonographic diagnosis and subsequent conservative surgical management of bilateral ureteroceles.

Prenatal sonographic diagnosis of ureteroceles usually involves clearly duplicated urinary collecting systems associated with ectopic ureters draining the upper renal moieties. We present an unusual case in which an initial sonographic examination was consistent with bilateral orthotopic ureteroceles in association with bilateral single renal systems. The possibility of single systems raised perinatal considerations unique to this anomaly. Repeat prenatal sonography was suggestive of duplex systems and subsequently confirmed as such by neonatal ultrasound and voiding cystourethrogram. At the age of 1 month, the infant underwent bilateral ipsilateral ureteroureterostomy with conservation of the bilateral dilated upper renal moieties. We discuss the possible pathophysiology underlying the different conflicting sonographic findings and address current management of such lesions.

Late presentation of cryptorchidism: the etiology of testicular re-ascent.

PURPOSE: We reviewed the records of 21 boys who had 23 previously documented descended testes that reascended and who underwent orchiopexy during a 2-year period. MATERIALS AND METHODS: We retrospectively reviewed a 2-year experience in 103 boys (115 undescended testes) who underwent orchiopexy in 1988 and 1989. RESULTS: In our 2-year experience 21 of the 103 boys with undescended testes had multiple recorded confirmations of testicular descent in the past. Of the boys 40% had previously been examined in the office or with general anesthesia by a pediatric urologist or pediatric surgeon for another reason, and 40% had a nurse or physician parent. Surgery was performed at ages 5 to 14 years, an average of 2 years after the initial presentation with reascent. Human chorionic gonadotropin was unsuccessful in causing testicular descent. There was no correlation with a patent processus vaginalis and no association with adhesions. The testis was located in the superficial inguinal pouch in the majority of patients, and the gubernacular attachment was in an abnormal location in all and ectopic in half of the cases. CONCLUSIONS: Our observations confirm that the etiology of this condition is a missed diagnosis at a younger age. The testis is undescended but almost completely descended. With somatic growth the distance between the terminal portion of the gubernaculum of the apparently descended testis and the scrotum increases, making the diagnosis more obvious. The potential for this condition makes it mandatory that intrascrotal testicular location be confirmed by periodic physical examination through puberty.

Metabolic sources of heat and power in tuna muscles. II. Enzyme and metabolite profiles.

Tuna appear able to maintain their muscles at 5-10 degrees C above ambient by balancing heat produced in situ and conserved by a counter-current heat exchanger with heat lost to the sea. Metabolite profiles under three different activity states (rest, burst swimming, and steady state swimming during feeding frenzies at sea) were used to identify which metabolic processes in white and red muscles could account for observed excess temperatures. During burst swimming, transient changes in metabolite levels indicate that the metabolism of both red and white muscle contributes to powering burst swimming; red muscle work is sustained mainly by oxidative metabolism while white muscle work depends upon an intense anaerobic glycolysis. The rate of metabolism in red muscle is easily high enough to account for the measured (10 degrees C) increase in temperature at this time. However, in white muscle, anaerobic glycolysis can account for only about a 2 degrees C maximum rise in temperature. The highest sustained swimming speeds and the highest muscle temperatures in skipjack are found during feeding frenzies at sea. As in burst swimming, during steady-state swimming red muscle temperatures can be accounted for by oxidative metabolism. In the case of white muscle, the lactate measurements indicate that anaerobic glycolysis could only lead to a 0.3 degree C temperature rise. However, if the fraction of utilized glycogen that is not fermented (about 60%) is assumed to be fully oxidized, enough heat is generated to raise white muscle temperatures by over 10 degrees C. The observed excess temperature at this time is about 8-10 degrees C, showing that anarerobic carbohydrate metabolism in white muscle is probably the major heat source during feeding frenzies. These interpretations are fully consistent with enzyme profiles of red and white muscles in tuna. They do not, however, explain why tuna have warm muscles. The latter problem is briefly discussed.

Does urinary tract ultrasonography at hospitalization for acute pyelonephritis predict vesicoureteral reflux?

PURPOSE: We evaluate the correlation between urinary tract ultrasound during hospitalization for acute pyelonephritis with subsequent voiding cystourethrography in children. MATERIALS AND METHODS: Medical records were reviewed of 184 children up to 18 years old who were evaluated with ultrasound during hospitalization for acute pyelonephritis between January 1988 and January 1996. Followup voiding cystourethrography results were compared to the initial ultrasound findings. RESULTS: Ultrasound was performed at mean hospital day 2.1 and voiding cystourethrography was done 39 days later. Of the ultrasound studies 77 (42%) were abnormal, and two-thirds of these abnormalities were upper tract dilatation. Subsequent voiding cystourethrography was performed in 76% of the study population, including 67% of those with normal and 87% of those with abnormal ultrasound. Voiding cystourethrography revealed reflux in 39% of children with upper tract dilatation compared to 35% of those with normal and 36% with abnormal ultrasound for any reason. In addition, the severity of reflux on voiding cystourethrography could not be predicted by ultrasound findings. CONCLUSIONS: Ultrasound findings during acute pyelonephritis do not correlate with and are not predictive of the presence or grade of vesicoureteral reflux on subsequent voiding cystourethrography.

The site of leukocyte migration through the tracheal mucosa in the guinea pig.

The tracheal mucosa of the guinea pig was examined using light microscopy, thin section, and freeze-fracture replicas with transmission electron microscopy and scanning electron microscopy. These studies demonstrated that inflammatory cells en route to the mucosal surface migrate through the epithelium in file through solitary openings rather than randomly between epithelial cells. The fact that leukocytes migrate through these openings rather than randomly between epithelial cells has important implications. First, it provides a pathway for circulating cells to gain access to the surface of the airway where they can function as the first line of defense against inhaled material. Second, the movement of leukocytes through specified pathways rather than randomly between cells minimizes the number of openings required for cell transit so that fluid and solute movement can be more tightly controlled. Third, the prevention of random migration may also be important in minimizing the contact between the migratory cells and the epithelial sensory nerve net.

Arteriovenous malformation of the spermatic cord.

We report a case of an arteriovenous malformation of the spermatic cord, a lesion that to our knowledge has not been described previously.

Scanning electron microscopy of elastic networks from the bifurcation region of guinea pig carotid arteries.

We isolated the elastic network from the bifurcation region of guinea pig carotid arteries by treatment with hot alkali and examined its adventitial and adluminal components by SEM. The thickness of networks from common and external carotid arteries averaged 87.5 microns (+/- 6.9 SD) and from the carotid sinus averaged 46.8 microns (+/- 2.4 SD). The networks consisted of a mesh of elastic tissue that became a continuous sheet, 2 microns thick, which formed the internal elastic lamina (IEL). The IEL was fenestrated; the perforations varied in number among the vessels (occipital greater than carotid sinus greater than common = external carotid), and some were spanned by delicate elastic fibers. The IEL's adluminal surface was a smooth membranous sheet, which in some specimens bore unidirectional loose fibers, or was composed of tightly fused bundles of uni- or multidirectional fibers. The interior region of the cranial carotid sinus contained unique blister-like structures and dense clusters of fenestrations, together with a honeycomb-like mesh near the ascending pharyngeal artery. The outer, adventitial elastic layer consisted of a network of loose elastic fibers that were fused with the inner layers. We conclude that the structural differences noted among the common and external carotid arteries and carotid sinus are related to the sinus's unique pressure-sensing functions.