Search PubMed⌕ Search

Biomedical subjects

M O Koch

Publications and source records attributed to M O Koch.

At least 73 records · Page 4Linked to original sources
PubMed1991

Metabolic alterations following continent urinary diversion through colonic segments.

This study examined acid-base metabolism in patients with continent colonic urinary diversions and compared them to a control population. Diverted patients demonstrated mild acidosis and a urinary acidification defect. Ammonium chloride loading failed to demonstrate any major differences in the ability of these patients to handle an acute acid challenge. Continent colonic urinary diversions do not appear to create significant acid-base changes in patients with normal hepatic and renal function.

Acid-Base Equilibrium↗
PubMed1991

Cavoatrial tumor thrombectomy using cardiopulmonary bypass without circulatory arrest.

Of 29 patients with inferior vena caval tumor thrombus, 14 with supradiaphragmatic extension were deemed suitable for operation. Patients (age, 7.5 to 70 years) had renal cell carcinoma (n = 8), Wilms' tumor (n = 2), transitional cell carcinoma (n = 1), and adrenal carcinoma (n = 3). Seven patients had stage III disease, and 7 patients had stage IV disease. Two patients (group A) had unresectable disease at exploratory celiotomy, 4 patients (group B) underwent tumor thrombectomy without cardiopulmonary bypass, and cardiopulmonary bypass was employed in 8 patients (group C). Three of 8 group C patients had Budd-Chiari syndrome at diagnosis. Cardiopulmonary bypass with moderate hypothermia, and inferior vena caval interruption (clip or filter), was employed in all patients. There were no perioperative deaths. Transient neurological impairment was observed postoperatively in 2 patients. Coagulopathy developed in 1 patient who had hepatic encephalopathy and Budd-Chiari syndrome preoperatively and in another patient in whom protamine could not be administered. No patient had acute renal failure requiring hemodialysis. Median survival is 41 and 17 months in groups B and C, respectively. Some authors have advocated profound hypothermia and circulatory arrest in these patients. We find that satisfactory visualization and excision can be performed with cardiopulmonary bypass and moderate hypothermia, avoiding potential renal, hepatic, neurological, and septic complications associated with circulatory arrest.

Adolescent↗
PubMed1991

Metabolic consequences of urinary diversion through intestinal segments.

The use of intestinal segments in the reconstruction of the urinary tract for a variety of malignant and nonmalignant conditions is generally accepted. Metabolic derangements may result any time urine is in contact with the intestinal mucosa. Numerous studies concerning the pathophysiology of this syndrome have demonstrated that it is in large part secondary to reabsorption of urinary acid as ammonium and, to a lesser degree, to bicarbonate secretion into the urine. The syndrome of metabolic acidosis resulting from urinary diversion has been most common after ureterosigmoidostomy, often in the setting of renal insufficiency secondary to pyelonephritis and obstruction. It became a lesser clinical problem with the popularization and frequent use of conduit urinary diversions. At present, with a greater emphasis on the construction of large-capacity continent urinary diversions, there is an increased likelihood of metabolic derangements, especially in the setting of renal insufficiency. Furthermore, although the reported incidence of clinically problematic metabolic derangements is low with the newer modes of continent urinary diversion, it is impossible to assess the significance of a mild or asymptomatic acidosis, which may occur even in the setting of normal serum electrolytes. Only with close long-term follow-up can the significance of this change be determined.

Acidosis↗
PubMed1990

Adenocarcinoma in a sigmoid conduit: case report.

The increased risk of developing adenocarcinoma in the sigmoid colon after ureterosigmoidostomy has been acknowledged for some time. Development of adenocarcinoma in colonic conduits isolated from the fecal stream is rare. We report a case of adenocarcinoma arising in a sigmoid conduit that probably represents a metachronous adenocarcinoma of the colon.

Adenocarcinoma, Mucinous↗
PubMed1990

Physiologic and pathologic alterations associated with ultrasonically generated shock waves.

Kidneys of 25 dogs were treated with ultrasonic shock waves and examined for both physiologic and pathologic changes. The number of pulses ranged from 2,000 to 8,000. The rate of the shock waves varied from one to 20 pulses per second. The difference in pulse rate did not affect the changes seen either acutely or in the delayed examination of the kidneys during the repair process. The physiologic and pathologic changes which occurred involved the renal tubule to a greater degree than the glomerulus. These alterations were resolving by one week following exposure to the shock waves.

Animals↗
PubMed1990

Urinary solute transport by intestinal segments: a comparative study of ileum and colon in rats.

This study was conducted to quantitate and compare urinary solute transport by ileum and colon in an in vivo rat model. Rates of solute transport were compared by analysis of rate constants for each experiment. Sodium and bicarbonate are secreted while ammonium and chloride are absorbed by both ileum and colon. Potassium is absorbed by ileum and not transported by colon. There is a tendency for water movement into the bowel lumen with both intestinal segments. Quantitatively, the amount of bicarbonate secretion and the increase in intraluminal pH is greater with ileum than colon. There is a net osmolar absorption from ileum but not colon. Hydrogen ion or ammonium absorption accounts for the majority and bicarbonate secretion the minority of the acid load in both ileum and colon. Ammonium appears to be absorbed either along with chloride or in exchange for sodium.

Acid-Base Equilibrium↗
PubMed1989

Penile carcinoma: the case for primary lymphadenectomy.

In the preceding sections, the authors have presented an approach to the management of patients with squamous-cell carcinoma of the penis selected to maximize the therapeutic benefits in high-risk patients while minimizing morbidity in low-risk patients. A clinical staging system is presented in order to approach this problem in a logical fashion. Patients with stage I penile carcinomas are all managed by eradication of the primary lesion followed by expectant management of the inguinal lymph nodes. Persistent inguinal adenopathy after treatment of the primary lesion has been a very rare occurrence in this group of patients in our experience. Patients with stage II penile carcinoma are managed by eradication of the primary lesion, 6-8 weeks of antibiotic therapy, and inguinal lymphadenectomy. The available literature suggests a high incidence of inguinal lymphatic metastases in this group of patients and supports the need for early lymphadenectomy. Finally, patients with clinical stage III disease, i.e., persistent adenopathy after eradication of the primary lesion and 6-8 weeks of antibiotic therapy, all undergo inguinal lymphadenectomy. This group is at extremely high risk and does poorly without aggressive surgical management.

Humans↗
PubMed1989

Effect of sulfate on calcium and magnesium homeostasis following urinary diversion.

The present investigation was undertaken to elucidate the mechanisms of renal calcium and magnesium wastage in patients with urinary diversion through intestinal segments. Patients with urinary intestinal diversions demonstrated a hyperchloremic metabolic acidosis, increased serum sulfate and phosphate, and increased urinary excretion of calcium, phosphate, sulfate, and magnesium. A study was conducted in rats utilizing oral or intravenous loads of various solutes to investigate the possible mechanisms of these findings in patients. Ammonium enhances renal sulfate excretion and intestinal sulfate absorption. Increased filtered loads of sulfate inhibit renal tubule sodium and calcium reabsorption. Dietary ammonium and sulfate result in increased serum phosphorous concentrations. Ammonium appears to directly inhibit renal magnesium reabsorption. Renal tubule dysfunction resulting from relieved obstruction appears to enhance the inhibitory effect of sulfate on renal sodium and calcium reabsorption but does not alter the effect of ammonium on renal magnesium excretion. Taken together, these findings suggest that patients with hyperchloremic metabolic acidosis from the chronic reabsorption of ammonium chloride by intestinal urinary diversions may also reabsorb urinary sulfate. This load of ammonium and sulfate inhibits renal calcium and magnesium reabsorption.

Acidosis, Renal Tubular↗
PubMed1988

Bony demineralization following urinary intestinal diversion.

The effect of urinary intestinal diversion on bone mineral metabolism was investigated in 78 rats. The animals were divided into sham-operated controls and diverted animals. The diverted animals were given either no supplement, sodium bicarbonate or ascorbic acid for an eight month period. Dual photon densitometry and bone mineral content were determined. Urinary intestinal diversion resulted in a minimal systemic acidosis and little alteration in baseline renal function but a significant decrease in bone calcium content. Oral bicarbonate and ascorbic acid administration prevented the demineralization.

Acidosis↗
PubMed1988

Bone demineralization following ureterosigmoid anastomosis: an experimental study in rats.

This study was designed to examine the renal and bony metabolic responses to urinary diversion through intestinal segments. Twenty rats underwent urinary diversion by ureterosigmoidostomy and were compared to twenty control rats with respect to renal excretion of electrolytes and bone mineralization after a 10-week period. Ureterosigmoidostomy rats demonstrated increased renal excretion of ammonium, sulfate, magnesium, and possibly phosphorus. Bone calcium content was decreased in ureterosigmoidostomy rats, while bone phosphorus content was slightly increased. These changes occurred in the absence of systemic acid-base alterations. We are unable to demonstrate an increased renal loss of calcium in the ureterosigmoidostomy rats compared to controls. This suggests that decreased renal reabsorption of urinary calcium is not the primary pathophysiologic process involved in this problem.

Acidosis↗
PubMed1988

Urologic causes of the acute abdomen.

This article reviews renal and perirenal infections, obstructing conditions of the renal pelvis and ureter, and acute intrascrotal events. Each subject is reviewed with regard to patterns of presentation, means of diagnosis, and treatment options. Emphasis is placed on new modalities in the evaluation and treatment of these conditions.

Abdomen, Acute↗
PubMed1986

Accurate determination of renal function in patients with intestinal urinary diversions.

The regular determination of renal function is a critical part of the management of patients who have had the urinary tract reconstructed with intestinal segments. These intestinal segments reabsorb urinary solutes and, thereby, complicate the determination of renal function by conventional methods. Urinary clearances of urea, creatinine and inulin were performed in patients with intestinal segments in the urinary tract and controls under varying diuretic conditions. Patients with intestinal diversions also underwent radioisotopic determination of renal function. The urinary clearances of urea, creatinine and inulin are highly dependent on the rate of urine flow in patients with intestinal segments in the urinary tract. Diuresis maximizes the urinary clearances of these solutes by minimizing intestinal reabsorption. Creatinine clearance prediction from the serum creatinine underestimates true glomerular filtration rate. Radioisotopic determination of renal function correlates poorly with true glomerular filtration rate. Only creatinine clearance measured under diuretic conditions correlates well with true renal function. Urine concentrating ability cannot be assessed accurately in patients with intestinal segments in the urinary tract, since osmolality rapidly equilibrates across the segments.

Adolescent↗
PubMed1985

Nicotinic acid: treatment for the hyperchloremic acidosis following urinary diversion through intestinal segments.

The syndrome of hyperchloremic metabolic acidosis following urinary diversion through intestinal segments has posed a problem for urologists for more than 50 years. Recent work demonstrates that chlorpromazine, an intestinal cyclic-AMP inhibitor, partially corrects the metabolic derangements associated with this syndrome. Nicotinic acid has also been shown to be a potent inhibitor of intestinal cyclic-AMP. The present investigation employs nicotinic acid in a rat vesico-cecostomy model to examine its efficacy in the management of this syndrome. Rats with vesico-cecostomies treated with nicotinic acid are compared to untreated rats, rats with intestinal but not urinary diversions and non-operative controls. Nicotinic acid in a dose of 50 mg./kg./day corrects the hyperchloremia (p less than 0.02), elevated serum osmolality (p less than 0.0001), hyperammoniumemia (p less than 0.05) and acidosis (p less than 0.001). Results compare favorably to those obtained in an identical model with the use of chlorpromazine.

Acidosis↗
PubMed1985

Chlorpromazine: adjuvant therapy for the metabolic derangements created by urinary diversion through intestinal segments.

The hyperchloremic metabolic acidosis which can occur following urinary diversion through intestinal segments has been managed with bicarbonate or citrate salts. However, satisfactory management is not always possible with this form of treatment. The development of this acidosis has been attributed to intestinal reabsorption of urinary solutes or intestinal secretion of bicarbonate. Intestinal absorptive and secretory processes are modulated by an adenylate cyclase-cyclic AMP system. Chlorpromazine inhibits the effect of cyclic AMP on the intestinal mucosal cell. The use of chlorpromazine in the management of the hyperchloremic metabolic acidosis following urinary diversion was investigated. A canine model employing an ileal segment between ureter and bladder and a rat model in which urine is diverted through the entire colon have been developed. Chlorpromazine (5 mg./kg./day) was found to be efficacious in the management of the metabolic derangements that occur in both of these models. A case study is presented in which conventional management of this syndrome with bicarbonate salts was unsuccessful. The use of chlorpromazine as an adjuvant treatment allowed correction of the acidosis.

Acidosis↗
PubMed1985

Determination of renal function following urinary diversion through intestinal segments.

Serum concentrations of urea and creatinine, urinary clearances of urea and creatinine, and urine concentrating ability have been proposed as measures for determining renal function in patients with urinary diversion through intestinal segments. Intestinal segments reabsorb urinary solutes, including urea and creatinine, complicating these methods of assessing renal function. This study employs a canine model in which urinary clearances of urea, creatinine and inulin are determined through a normal renal unit and ureter and compared with the contralateral renal unit which has had its ureter replaced by a segment of ileum. Urea, creatinine and inulin are reabsorbed by the ileal segment. Reabsorption of each of these solutes is dependent on urinary flow. The clearance of these solutes through the renal unit with the interposed ileal ureter approaches that of the contralateral renal unit under maximal degrees of diuresis. Creatinine and inulin clearances obtained during diuretic states give the most accurate indication of true renal function. These solutes are reabsorbed to a lesser extent than urea. Diuresis minimizes reabsorption of all these solutes by the ileal segment. Urine concentration does not reflect distal tubule function since the ileal segment reabsorbs urinary solutes and is freely permeable to water.

Animals↗