Biomedical subjects

J C Pope

Publications and source records attributed to J C Pope.

29 records · Page 2Linked to original sources

PubMed1997

Evaluation of renal resistive index, maximum velocity, and mean arterial flow velocity in a hydronephrotic partially obstructed pig model.

RATIONALE AND OBJECTIVES: The authors investigate, in a controlled pig model, the usefulness of Doppler sonographic measurements of resistive index (RI), maximum velocity (Vmax), and mean velocity (Vmean) in diagnostic evaluation of the partially obstructed kidney. METHODS: Seven female pigs underwent surgical partial unilateral renal obstruction at the ureteropelvic junction. Doppler parameters of RI, Vmax, and Vmean were measured preoperatively and postoperatively in obstructed and contralateral nonobstructed kidneys. The General Linear Model multivariate analysis of variance was used for statistical analysis of data. RESULTS: There was no significant difference in the preoperative control values of RI (P = 0.71), Vmax (P = 0.27), and Vmean (P = 0.12). There was a statistically significant decrease in the Vmax and Vmean after postoperative day 5 in the obstructed kidney compared with the contralateral nonobstructed kidney (P = 0.01 and 0.03, respectively). There was no statistically significant difference in RI during the study. CONCLUSIONS: In this study, RI was not a reliable indicator of partial renal obstruction. Measurements of maximal and mean blood flow velocities reached discriminatory significance only after the fifth postobstructive day, proving insensitive in the immediate postobstructive period. Vmax and Vmean demonstrated a decrease in the partially obstructed renal collecting system after 5 days of obstruction and may serve as useful parameters in the evaluation of obstruction after the immediate acute period, when compared with a nonobstructed contralateral system.

Animals↗

PubMed1997

The ontogeny of canine small intestinal submucosa regenerated bladder.

PURPOSE: Small intestinal submucosa has previously been shown to promote regeneration of transitional epithelium, smooth muscle and peripheral nerves in rat and dog bladders. The origin of these regenerated components is presently unknown. This study attempts to define the origin of vascular, smooth muscle and peripheral nerve regeneration. MATERIALS AND METHODS: A total of 22 adult male dogs weighing 25 to 30 kg. underwent partial cystectomy and immediate augmentation with a small intestinal submucosa patch graft. The small intestinal submucosa graft-native bladder interface was marked with permanent marking sutures for future reference. Small intestinal submucosa regenerated bladders were harvested at 2, 3, 4, 6, 8 and 10 weeks after augmentation. The tissue was then studied with routine histology and immunohistochemistry using factor VIII, smooth muscle specific actin (1A4) and neurofilament staining. RESULTS: Results demonstrated that epithelialization of the graft surface was complete by 3 to 4 weeks with normal transitional histology. In the early periods neovascularization was prominent throughout the entire graft, as shown by factor VIII staining. Later more mature vessels were noted. Early in muscle formation sheets of elongated spindle cells extended into the graft from the incised native bladder at both surgical margins and ran parallel to the mucosal surface. At 4 weeks this spindle cell proliferation completely traversed the graft. Trichrome stained sections of the 4-week-old grafts showed no evidence of muscle differentiation and the spindle cells appeared to be fibroblasts. However, these cells stained positive for smooth muscle specific actin (1A4), indicating myogenic potential. Between weeks 4 and 6 the spindle cells became more haphazardly arranged and were separated by loose interstitium. By weeks 8 to 10 there was distinct smooth muscle bundle formation within these areas of proliferating myocytes. Neural regeneration appeared to coincide with smooth muscle development. Early neurofilament positive cells were noted predominantly at the graft-native bladder interface. At 4 weeks neurofilament positive cells were present throughout the graft and by 10 weeks nerve trunks composed of several nerve fibers were identified in association with newly formed smooth muscle bundles. CONCLUSIONS: Small intestinal submucosa serves as a platform for bladder regeneration. Neovascularization smooth muscle and neural regeneration appear to occur through pannus ingrowth from the graft-native bladder interface. Smooth muscle regeneration seems to begin with the maturation of myofibroblasts, which migrate into the graft as early as 2 weeks after augmentation, and it progresses to the formation of distinct smooth muscle bundles by 10 weeks.

Animals↗

PubMed1997

Management of ectopic ureters: experience with the upper tract approach.

PURPOSE: The necessity of removing the ureteral stump after upper tract surgery for an ectopic ureter has been debated. We reviewed the records of patients initially treated at the kidney level to evaluate indications for later stump removal. MATERIALS AND METHODS: We reviewed the medical records of 32 patients with 33 ectopic ureters treated at the kidney level during the last 10 years. RESULTS: Ectopic ureters were associated with duplicated collecting systems in 31 cases and with single systems in 2. Upper pole heminephrectomy and partial ureterectomy were performed in 23 units and upper tract reconstruction was done in 8. Both patients with single systems underwent nephrectomy. Four patients (12%) required repeat surgery at the bladder level, including 1 who underwent ureteral reimplantation for persistent ipsilateral lower pole reflux and simultaneous upper pole stump removal. Preoperative voiding cystourethrography revealed reflux into the ectopic ureter in 1 patient with postoperative reflux and infections. The remaining 2 patients required a repeat operation to remove the stump due to recurrent urinary tract infections and newly detected reflux into the stump, respectively. CONCLUSIONS: The majority of patients with ectopic ureters can be treated by addressing only the upper urinary tract. No patient who presented with incontinence required ureteral stump removal. Whether noted preoperatively or postoperatively, reflux into the ectopic ureter necessitated ureteral stump removal. Three of the 6 patients (50%) who had reflux to the ipsilateral kidney required lower tract surgery.

Abnormalities, Multiple↗

PubMed1997

Reconstruction of the high urogenital sinus: early perineal prone approach without division of the rectum.

PURPOSE: Reconstruction of the vagina and external genitalia in the infant is quite challenging, particularly when a urogenital sinus is associated with high confluence of the vagina and urethra. Many surgeons believe that children with such a malformation should undergo staged or delayed reconstruction, so that vaginoplasty is done when the child is older and larger. Vaginoplasty early in life is thought to be difficult due to patient size and poor visualization. The posterior sagittal approach has been beneficial for acquiring exposure to high urogenital sinus anomalies but it has been thought to require splitting of the rectum and temporary colostomy. We report a modification of this technique. MATERIALS AND METHODS: In the last 5 years all patients with urogenital sinus anomalies underwent reconstruction using a single stage approach regardless of the level of confluence. In 8 patients with a high level of confluence reconstruction was performed using a perineal prone approach. Exposure was achieved without division of the rectum. The operative technique is presented in detail. RESULTS: This midline perineal prone approach has allowed excellent exposure of the high vagina even in infants. In all 8 patients reconstruction was done without difficulty and no patient required incision of the rectum or colostomy. This procedure did not preclude the use of a posteriorly based flap for vaginal reconstruction. CONCLUSIONS: While patients with low confluence can be treated with single posteriorly based flap vaginoplasty, those with higher confluence may benefit from a perineal prone approach to achieve adequate exposure for pull-through vaginoplasty. This prone approach to the high urogenital sinus anomaly can be performed without division of the rectum, provides excellent exposure of the high confluence even in small children and does not preclude the use of posterior flaps for vaginal reconstruction.

Abnormalities, Multiple↗

PubMed1996

Penile orthoplasty using dermal grafts in the outpatient setting.

OBJECTIVES: To review and evaluate our extensive outpatient experience in the use of dermal grafts for the correction of significant residual chordee in patients requiring penile orthoplasty. METHODS: The medical records of all patients requiring surgical correction for severe penile curvature over the past 5 years were reviewed. Among these, 51 patients were identified in whom dermal grafts were used to correct severe residual chordee. Of these patients, 41 had severe hypospadias, 9 had epispadias, and 1 had urethral atresia. Graft harvest and placement technique, any resulting complications, and parental satisfaction with cosmetic and functional results were all evaluated. RESULTS: The dermal grafts were harvested from the hairless skin of the inguinal area, using one of two techniques. All were used to fill a tunical defect created by incising the tunica at the point of maximal penile curvature. No complications or postoperative hospitalizations resulted from any of the orthoplasty procedures. At a mean follow-up of 27 months, all patients had excellent cosmetic and functional results. CONCLUSIONS: In patients with significant residual chordee, a dermal graft is our preferred method of penile orthoplasty. This technique provides a straight phallus with a very minimal complication rate, it can easily and successfully be performed as an outpatient procedure, and it has assured an excellent cosmetic and functional result.

Ambulatory Surgical Procedures↗

PubMed1996

The natural history of nephrocalcinosis in premature infants treated with loop diuretics.

PURPOSE: We investigated the natural history of nephrocalcinosis in premature infants treated with furosemide and attempted to identify factors to predict infants most at risk. MATERIALS AND METHODS: We evaluated 13 preterm infants in this longitudinal pilot study. During hospitalization and while receiving a loop diuretic nephrocalcinosis developed in each patient. Patients were divided into groups based on resolution (6) and nonresolution (7) according to spontaneous resolution of nephrocalcinosis at any point during followup. The 2 groups were compared to each other and to a control group. RESULTS: Mean followup after discontinuation of furosemide in the resolution versus nonresolution groups was 10.3 and 7.7 months, respectively. Between the 2 groups there was no significant difference in average gestational age, birth weight, number of days hospitalized or on furosemide, or total furosemide dose. Mean calcium-to-creatinine ratio while receiving furosemide at the time nephrocalcinosis developed was 0.38 in the resolution group but 2.23 in the nonresolution group (p < 0.005). Initial calcium-to-creatinine ratio in age matched infants who did not have nephrocalcinosis was 0.4. Frank renal stones developed in 2 of the 7 patients without resolution and 0 of the 6 with resolution. When nephrocalcinosis resolved, it was at a mean of 5.2 months following discontinuation of the diuretic. CONCLUSIONS: Early data indicate that nephrocalcinosis resolves in approximately 50% of premature infants 5 to 6 months after discontinuation of furosemide. The only factor that appears to be predictive of the infants who will have resolution is the calcium-to-creatinine ratio when nephrocalcinosis is diagnosed. In patients without resolution this ratio is much higher than in age adjusted normal controls, while in those with resolution it appears normal for age.

Diuretics↗

PubMed1996

The value of Doppler resistive index and peak systolic velocity in the evaluation of porcine renal obstruction.

PURPOSE: We evaluated the use of Doppler resistive indexes and systolic velocities as diagnostic tools in a partially obstructed animal model. MATERIALS AND METHODS: We studied 12 normal pigs by Doppler sonography, which served as control units. In 9 subjects partial ureteral obstruction was then created surgically, and 3 continued as controls. The presence or absence of obstruction was confirmed by ultrasound, antegrade nephrostography and intrapelvic pressure monitoring. Doppler parameters were measured 1 hour to 21 days postoperatively. Resistive index, and angle corrected peak and mean systolic velocities were measured bilaterally from samplings of interlobar and arcuate arteries. An average of 4 samplings per kidney was obtained at each session. Data from the control and obstruction groups were compared for statistical differences. RESULTS: In controls mean resistive index was 0.53, and peak and mean systolic velocities were 0.38 and 0.26 m. per second, respectively. In the subacute period after obstruction (defined as days 4 to 21) mean resistive index was 0.54, and peak and mean systolic velocities were 0.33 and 0.22 m. per second, respectively. Compared to control data there was no significant change in resistive index after obstruction (p = 0.6). However, peak and mean systolic velocities showed significant downward trends (p < 0.05). CONCLUSIONS: Known small sequential changes in renal blood flow after ureteral obstruction are reflected in flow velocities, as measured by duplex Doppler sonography. However, resistive indexes are not useful in assessing these changes in renal blood flow, and they do not correlate with the presence or absence of obstruction in this animal model.

Animals↗

PubMed1995

Nitric oxide stabilizes the Mo(V) oxidation state of dimethyl sulfoxide reductase from Rhodobacter sphaeroides without inhibiting enzyme activity.

Dimethyl sulfoxide reductase from Rhodobacter sphaeroides is isolated in an oxidized, Mo(VI) containing form. Both nitric oxide and reduced ascorbate carried out a one electron reduction of the enzyme with formation of stoichiometric amounts of EPR active Mo(V). Nitric oxide also caused a one electron oxidation of reduced, Mo(IV) enzyme. Mo(V) formation was accompanied by appearance of absorbance peaks at 387 and 528 nm. Neither nitric oxide nor ascorbate inhibited the enzyme nor did either compound support enzyme turnover. Both nitrite plus ascorbate and nitroxyl anion (NO-) induced a previously reported rhombic EPR signal (g1 = 1.994, g2 = 1.982, g3 = 1.966) which exhibited superhyperfine coupling to an exchangeable proton (A1 = 1.25 mT, A2 = 0.85 mT, and A3 = 1.0 mT). On the other hand, NO(g) induced an axial signal with g perpendicular = 1.982 and g parallel = 1.961 in which there is no evidence of superhyperfine coupling. Thus, ascorbate, nitric oxide, and nitric oxide donors induce and stabilize Mo(V) formation in dimethyl sulfoxide reductase without inhibiting enzyme activity. The resemblance between NO and the natural N-oxide substrates of this enzyme suggest that the Mo(V)-NO complex may be a transition state analog of the enzyme-substrate complex.

Ascorbic Acid↗

PubMed1994

Renal cell carcinoma in patients with end-stage renal disease: a comparison of clinical significance in patients receiving hemodialysis and those with renal transplants.

OBJECTIVES: This review was undertaken to determine the clinical significance of renal cell carcinoma in the populations undergoing renal transplantation and those undergoing chronic dialysis. METHODS: We reviewed all medical records of patients with renal cell carcinoma treated at our institutions over the last 10 years. From this review we identified 20 patients with end-stage renal disease and renal cell carcinoma. Patients' charts were reviewed to determine presenting features, tumor histologic type, and clinical outcome. RESULTS: Seven patients had functioning renal transplants and 13 patients were on chronic maintenance hemodialysis. Ninety-two percent of the dialysis group had no metastatic disease and there were no deaths from renal cancer. In contrast, 53% of the transplant group did have metastatic disease and 2 patients died of renal cancer. Despite similar pathologic appearances of the tumors in these 2 groups, patients with renal cell carcinoma and renal transplant presented with higher-stage disease and had less favorable clinical courses. CONCLUSIONS: Considering the morbidity of hemodialysis as well as the other comorbidities of this patient population, the clinical significance of renal cell carcinoma in patients undergoing chronic dialysis must be questioned. In contrast, renal cancer in the transplant population behaves aggressively and warrants careful attention both before and after renal transplantation.

Adult↗

PubMed1994

Intrapelvic pressure monitoring in the partially obstructed porcine kidney.

OBJECTIVES: The diagnosis of urinary obstruction in newborns and infants remains difficult because the diagnostic studies available at present are fraught with many problems. It is our premise that precise measurement of renal pelvic pressures under physiologic conditions in patients with urinary tract dilation will allow diagnosis of obstruction and prediction of further renal damage. This study evaluates an intrapelvic pressure monitoring system. METHODS: Four porcine subjects had partial ureteropelvic junction obstruction created surgically; two subjects were used as controls. Doppler ultrasound and MAG-3 furosemide renography were performed preoperatively and each week pressures were measured with a Millar 5 F solid-state pressure transducer and the analog signals were converted on line to digital information to allow signal processing and later data analysis. Antegrade nephrostograms were obtained at the same sitting and showed that the model remained stable over time. Measurements were obtained at physiologic flow rates as well as at the standard Whitaker infusion rate of 10 cc/min. RESULTS: Thirteen pressure studies were performed on 9 kidneys. Each study was classified as normal (4), partial obstruction (8), or total obstruction (1), based on ultrasound and nephrostogram criteria. The normal units had baseline pressures of 4.12 +/- 0.94 cm water (H2O), which increased to 9.12 +/- 1.38 cm H2O with infusion. In the partially obstructed group, baseline was 16.4 +/- 3.83 cm H2O and increased to 35.3 +/- 15.9 cm H2O with infusion. The kidney with total obstruction showed a baseline pressure of 27 cm H2O, which increased to 68 cm H2O with infusion. These pressure measurements were also compared to furosemide renography. CONCLUSIONS: Intrapelvic pressures correlated well with conventional ultrasound and nephrostogram in the evaluation of partial obstruction. However, the results of furosemide renography and the Whitaker test were quite variable and did not accurately define partial obstruction or correlate with intrapelvic pressure. The Millar solid-state transducer monitoring system is an accurate method of evaluating the intrapelvic pressure and could possibly become a standard for diagnosing significant urinary obstruction against which other studies can be evaluated.

Animals↗

PubMed1975

Diagnosis and management of major vascular injuries: a review of 200 operative cases.

In a series of 250 civilian vascular injuries, 85 per cent were due to firearms and 50 per cent involved the torso, both of which represent an increased frequency of occurrence over other reports. There were 40 deaths, 31 of which occurred during operation or in the recovery room and were due to irreversible shock or coagulopathy. Of the nine late deaths, failure of the vascular repair was responsible for only three. In 124 extremity artery injuries, there were 12 leg amputations (10%) with shotgun wounds responsible for nine and popliteal artery injuries involved in seven. In gunshot wounds of the aorta and iliac arteries, there were five suture line disruptions in nine primary repairs and no disruptions in 11 patients repaired by grafts. The evidence indicates that an antibiotic soaked dacron graft is the method of choice to repair gunshot wounds of the aorta and iliac arteries at this time.

Amputation, Surgical↗