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Biomedical subjects

M E Mitchell

Publications and source records attributed to M E Mitchell.

At least 109 records · Page 6Linked to original sources
PubMed1989

Constant pressure perfusion: a method to determine obstruction in the upper urinary tract.

In an effort to define a more physiological method to determine obstruction in the upper urinary tract, the technique of constant pressure perfusion was studied in the canine and porcine models. In contrast to the constant flow technique of Whitaker, constant pressure perfusion is independent of upper tract compliance, uses low fixed pressures (7 to 12 cm. water) in the renal pelvis and measures flow rates from the upper tracts. In the canine and porcine models constant pressure perfusion demonstrated increased sensitivity and better discrimination between normal and partially obstructed systems relative to constant flow. Pressures in nonobstructed canine and porcine renal pelves are normally low (less than 8 cm. water) for flow rates into the bladder of 1 to 5 cc per minute. When using constant pressure perfusion in systems with partial distal ureteral obstruction, low or no flow is appreciated across the obstruction at renal pelvic pressures of 7 to 12 cm. water. By constant flow obstruction is defined in the same systems but only after renal pelvic pressures exceed 15 to 20 cm. water. We believe that there is clear clinical applicability.

Animals↗
PubMed1989

Renal transplantation into the reconstructed bladder.

In our experience with 821 renal transplants performed between 1974 and October 1987 we used the native or reconstructed bladder of the patient in all but 2 instances. Seven patients have undergone enterocystoplasty and subsequent renal transplantation, while 1 underwent bladder augmentation after transplantation. Of these 8 patients 4 have functioning grafts 6 months to 7 years after transplant or reconstruction. Renal transplantation coupled with enterocystoplasty in properly selected patients has acceptable morbidity and should be considered as an alternative to other forms of urinary diversion in allograft recipients.

Adolescent↗
PubMed1989

Liver function in protein-energy malnutrition measured by cinnamic acid tolerance and benzoic acid tolerance: effect of carnitine supplementation.

1. Rats fed on a protein-depleted diet for 8 weeks were repleted for 5 weeks on high-protein (HP), high-protein + 20 g DL-carnitine/kg (HP + C), or low-protein + 20 g DL-carnitine/kg (LP + C) diets. At 4 and 8 weeks of depletion, and 1 and 5 weeks of repletion, rats from each treatment group were given a benzoic acid tolerance test (BATT) or a cinnamic acid tolerance test (CATT) as a measure of liver function. 2. BATT and CATT measured the molar percentage of a test dose (1 mmol/kg body-weight) of benzoic acid or cinnamic acid excreted in the urine as hippuric acid within 24 h. Liver weight, liver lipid levels, and carnitine concentration in plasma and liver were also measured following liver-function testing. 3. BATT and CATT were severely impaired in protein-depleted rats, but returned rapidly to control levels following protein refeeding. Correlations of BATT and CATT with liver lipid concentration were high (r -0.49 and -0.62 respectively), and both tests show promise as clinical tests for liver function in protein-energy malnutrition. 4. Carnitine supplementation was required to return liver carnitine concentration of protein-depleted rats to control levels during repletion, but was not associated with accelerated reduction in liver fat concentration in protein-repleted rats.

Animals↗
PubMed1989

Fibronectin in multiple sclerosis lesions.

Cryostat sections of central nervous system (CNS) tissues of patients with multiple sclerosis (MS) and other CNS diseases were stained with antibodies to fibronectin, a macrophage fibronectin receptor component, fibrin/fibrinogen, and albumin using immunoperoxidase. In active, but not inactive, MS plaques vessel fibronectin was increased (to approximately 57% of Factor VIII+ vessels) over uninvolved MS and normal control white matter (P less than 0.001 for both). Fibronectin was primarily localized to vessel walls and amount of staining correlated with degree of inflammation. Active plaques and necrotic lesions also had extracellular fibronectin and fibrin/ogen. These molecules and the fibronectin receptor were found on macrophages. Albumin was more widely and diffusely distributed in lesions than fibronectin. Thus, in addition to extravasation from damaged vessels, fibronectin may be deposited on or synthesized by endothelial cells and macrophages in the CNS. Fibronectin could facilitate monocyte adhesion to endothelial cell luminal surfaces, promote migration of mononuclear cells, and enhance myelin phagocytosis in MS lesions.

Antibodies↗
PubMed1989

Intrapleural streptokinase in management of parapneumonic effusions. Report of series and review of literature.

Noncommunicating locules of fluid may develop in the setting of a thoracic empyema or a complicated parapneumonic effusion. When this occurs a single chest tube may not provide adequate drainage. In an effort to promote drainage and thereby obviate the need for further procedures, instillation of streptokinase into the involved pleural space has been advocated. This communication reviews the literature and reports our experience with intrapleural streptokinase. In our retrospective review of nine patients, instillation of streptokinase resulted in an obvious increase in chest tube drainage in six. Of the nine patients, four with improved drainage required no further procedures. Two patients with improved drainage and the three with no change in drainage required an additional chest tube, a decortication procedure, or were lost to follow-up. None of the four patients with an empyema were benefitted. Intrapleural instillation of streptokinase may be a useful adjunct in the treatment of a complicated parapneumonic effusion but appears less likely to be of benefit in the management of an empyema.

Adult↗
PubMed1988

Symphyseal diastasis in the absence of the exstrophy-epispadias complex.

Symphyseal diastasis in the absence of exstrophy or epispadias is rare. We reviewed 11 reported cases and present 2 of our own. Based upon our findings, we recommend a thorough physical examination in all patients. A voiding cystourethrogram in those with the radiographic finding of symphyseal diastasis in the absence of exstrophy or epispadias may be helpful. A significant number of patients have associated congenital anomalies.

Child↗
PubMed1988

Chronic renal failure and bladder augmentation: stomach versus sigmoid colon in the canine model.

A canine model for chronic renal failure and bladder augmentation with a segment of stomach or sigmoid colon (or control) was developed to evaluate the possible benefit of net chloride ion excretion noted in an earlier canine model for gastrocystoplasty. Gastrocystoplasty animals behaved similar to control animals relative to the sigmoid cystoplasty animals, tolerated significantly greater acid loading, did not have hyperchloremia with acidosis and had less weight loss with acidosis. Gastrocystoplasty seems to be superior to sigmoid cystoplasty in the azotemic canine.

Acidosis↗
PubMed1988

Gastrocystoplasty: an alternative solution to the problem of urological reconstruction in the severely compromised patient.

An isolated segment of stomach was used for bladder augmentation in 10 patients or construction of a continent urinary reservoir in 3. Diagnosis in these 13 patients included cloacal exstrophy (5), myelodysplasia (4), posterior urethral valves (2), radiation cystitis (1) and neurogenic bladder secondary to a rectal pull-through procedure (1). Indications for the use of stomach in bladder reconstruction were decreased renal function and acidosis (6 patients), insufficient large and small bowel (6) and decreased mucus production (1). Postoperative followup averaged 13 months (range 6 to 23 months). All patients have stable upper tracts radiographically and stable or improved renal function. Of 13 patients 10 require intermittent clean catheterization to empty and 11 are completely continent. Nine patients have remained free of infection, while 4 had asymptomatic bacteriuria. Mucus production is reduced relative to other intestinal segments and 10 patients require no bladder irrigations. Postoperative urodynamic evaluation is similar to that of ileocystoplasty or colocystoplasty. Use of stomach has protected these patients from the development of new or worsened hyperchloremic acidosis. Serum chloride values have decreased and serum total carbon dioxide values have increased after bladder reconstruction, particularly in patients with impaired renal function. Stomach should be considered when lower urinary tract reconstruction is necessary in such compromised patients.

Adolescent↗
PubMed1988

Collateral urethral duplication in the frontal plane: a spectrum of cases.

Collateral urethral duplication in the frontal plane is a rare anomaly. We report 3 cases of this variant of urethral duplication and review the literature. Double stream was the most frequent complaint and associated midline defects were common. Management, including a unique method of surgical intervention, is discussed.

Child, Preschool↗
PubMed1988

Renal transplantation in a patient with an artificial urinary sphincter device.

Use of the artificial urinary sphincter device has become widespread. We describe the successful transplantation of a renal allograft into a recipient with an artificial urinary sphincter. Pretransplant placement of a sphincter, intraoperative avoidance of the prosthetic device and proper urinary drainage perioperatively make the artificial urinary sphincter device a feasible means to provide continence in a renal transplant recipient.

Adult↗
PubMed1988

Urethral replacement with ureter.

Proximal or total urethral replacement was performed in 8 patients using distal ureter. This was accomplished by basing the ureteral segment solely on a vascular pedicle arising from the internal iliac artery. Diagnoses included classical bladder exstrophy in 4 patients, cloacal exstrophy in 3 and an imperforate anus with hypoplasia of the bladder neck and urethra in 1. Continence was achieved by a tunneled submucosal reimplantation into either the bladder (4 cases), gastric reservoir (2) or colonic reservoir (2). Although an isolated distal segment of ureter was used in each case, all segments have remained viable. With limited followup (5 to 44 months) continence with either normal voiding or intermittent catheterization has been achieved in 7 of the 8 patients. A distal ureteral segment should be considered potentially useful in the construction or reconstruction of the proximal (male) or total (female) urethra in patients with congenital urethral malformations.

Anus, Imperforate↗
PubMed1987

Intestinocystoplasty and total bladder replacement in children and young adults: followup in 129 cases.

A review of 129 consecutive young patients (average age 13.4 years) who underwent intestinocystoplasty or total bladder replacement during a 6 1/2-year period at our institution is presented. The most common diagnosis was myelodysplasia and the average followup was 44 months. The clinical and urodynamic aspects of 4 types of intestinocystoplasty (ileocecal, tubular sigmoid, sigmoid patch and ileal patch) are presented. All 4 operations resulted in a significant increase in bladder volume, with a decrease in filling pressure and, thus, improved vesical compliance. In combination with clean intermittent catheterization renal function was maintained or improved in 91 per cent and urinary continence was achieved in 82 per cent of the patients. Hyperchloremic acidosis requiring therapy was noted only in patients with pre-existing renal insufficiency, although mild hyperchloremia after cystoplasty was seen with all 4 types of cystoplasty. There were no operative mortalities. Significant surgical complications occurred in 36 per cent of the patients, the most common of which was vesicoureteral reflux in the ileocecal cystoplasty. Mass unit peristaltic contractions occurred in 34 per cent of the tubular-shaped bowel segments compared to only 10 per cent of the patch segments. These peristaltic contractions contributed to the greater postoperative morbidity noted in the tubular large bowel cystoplasties. The over-all success rate for intestinocystoplasty in this series was 84 per cent. Intestinocystoplasty is an effective procedure when used to increase the compliance of the lower urinary tract. In combination with clean intermittent catheterization it can be applied successfully to patients with neurogenic bladder dysfunction. Large and small bowel seem to have similar clinical and urodynamic properties. The type of intestinal segment used for intestinocystoplasty seems to be of less importance than the size and configuration. Large bowel in its native tubular configuration should be avoided.

Adult↗
PubMed1987

Gastrocystoplasty and colocystoplasty in canines: the metabolic consequences of acute saline and acid loading.

An experimental canine model was developed to quantitate the net transmural ion flux of colon and gastric segments used for augmentation cystoplasty. Gastrocystoplasty (4) or colocystoplasty (4) was constructed in 8 female mongrels. Acute intravenous saline and acid loading experiments were performed 2 to 4 weeks after cystoplasty. The mean solute excretion rates for sodium, chloride, phosphorus and ammonia exhibited opposite trends during acute saline and acid loading in this experimental model. The net flux of chloride, ammonia, phosphorus and sodium ions in the colocystoplasty animals was from the mucosa/urine surface to the serum (reabsorption). The opposite trend was true for the gastrocystoplasty. By not reabsorbing ammonium chloride, the gastrocystoplasty preserved an important renal mechanism for systemic acid elimination. This may help to prevent the hyperchloremic metabolic acidosis that can develop when urine comes in contact with small or large bowel segments.

Acid-Base Equilibrium↗
PubMed1987

Indiana continent urinary reservoir.

Cecoileal reservoirs were created in 29 patients. Tunneled ureteral implantations along the tenia of the cecum provided the antireflux mechanism. Plication or tapering of the terminal ileal segment along with the ileocecal valve provided the continence mechanism. The tubular configuration of the cecum was disrupted with either an ileal or sigmoid patch, or it was re-configured in a Heineke-Mikulicz type of closure to avoid bolus (unit) contractions. Short-term followup examination with excretory urography showed no upper tract obstruction. X-rays of the pouch showed no reflux and interviews revealed satisfactory continence in 93 per cent of the patients.

Adult↗
PubMed1987

Pediatric urinary diversion and undiversion.

Many things have changed in our management of the urinary tract of children and young adults. Important contributions from many sources have resulted in the refinement of therapy and the progression from diversion to undiversion and reconstruction. Primary urinary diversion is now uncommon. Patients with exstrophy, for example, are treated with primary bladder closure as newborns, and newborns with valves often are treated with primary valve ablation. Children with neurogenic bladder dysfunction resulting from myelodysplasia are rarely diverted, but are started at an early age with ICC. It is hoped that in future the contents of this article on diversion techniques and undiversion will be of historical interest, however. Note: The editors also have found the use of the Mitrofanoff procedure, utilizing a nonrefluxing tunnel and a catheterizable stoma made out of the ureter or appendix, to be a very valuable addition to the reconstructive surgeon's armamentarium. We also feel that use of detubularized bowel for either bladder augmentation or replacement provides more efficient storage capability. Occasional reports of extremely significant diarrhea after removal of the ileocecal segment from the intestinal tract have been reported in children with myelodysplasia.

Adolescent↗
PubMed1987

Subepithelial pyeloureteric lesions in patients with nephrostomy tubes.

Mural filling defects were identified in the renal pelves or ureters in five patients with nephrostomy tubes. In two patients, infection was documented. In the remaining patients, the urine was sterile. While typical ureteritis cystica associated with infection may be seen in patients with nephrostomy tubes, in some patients, other mechanisms are responsible for this appearance.

Adult↗