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Biomedical subjects

M O Koch

Publications and source records attributed to M O Koch.

At least 55 records · Page 3Linked to original sources
PubMed1994

Tumor volume and stage in carcinoma of the prostate detected by elevations in prostate specific antigen.

We reviewed the surgical specimen from 142 men undergoing radical prostatectomy for prostate cancer detected because of an elevation in serum prostate specific antigen alone. No patient had a palpable abnormality suggestive of cancer. One patient had no identifiable tumor in the radical prostatectomy specimen, 8 (6%) had only a few high power microscopic fields showing cancer, 40 (28%) had an estimated tumor volume of less than 1 cc and 93 (65%) had a tumor volume of greater than 1 cc. Surgical margins were positive in 37 patients (26%) and negative in 105 (73%). Most patients with cancer detected because of modest elevation in prostate specific antigen, even without palpable abnormalities, have a clinically significant tumor volume and are good candidates for radical prostatectomy.

Adenocarcinoma↗
PubMed1994

The ovarian remnant syndrome and ureteral obstruction: medical management.

The ovarian remnant syndrome represents the development of symptoms due to residual ovarian tissue after bilateral salpingo-oophorectomy. Treatment generally consists of surgical resection but recurrence after resection is common. A case is reported in which a postoperative recurrent ovarian remnant was successfully managed by using a luteinizing hormone-releasing hormone agonist. In addition, this report includes a survey of gynecologists to determine the frequency of this syndrome and of ureteral involvement.

Adult↗
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

Prospective development of a cost-efficient program for radical retropubic prostatectomy.

OBJECTIVES: We designed and implemented a broad-based program to decrease costs while maintaining quality of care in patients undergoing radical retropubic prostatectomy. METHODS: This program initially involved identification of factors that contribute to patient costs after radical prostatectomy and elimination or control of items that were deemed unnecessary. Patient care was standardized with a collaborative care pathway coordinated by a clinical nurse specialist and that served as a goal for each case. RESULTS: Length of total hospital stay was reduced from a mean of 5.7 days to 3.6 days after full implementation of the program (p < 0.0001). A reduction in operating room time, material utilization, antibiotic use, routine laboratory studies, and refinements in postoperative pain management contributed significantly to cost savings. Overall, the average adjusted total hospital charges were reduced from $13,783 to $7741 (p < 0.0001) by the implementation of this program, with no discernible adverse effect on morbidity rates. CONCLUSIONS: Careful analysis of the critical components of medical care and implementation of a standardized pathway with emphasis on a collaborative approach can substantially increase the cost efficiency of medical care.

Aged↗
PubMed1994

Urinary solute transport by gastric mucosa: a comparison with ileum using a rat model.

OBJECTIVES: This study was conducted to quantitate and compare urinary solute transport by stomach and ileum using an in vivo rat model. METHODS: An artificial urine solution was perfused through isolated gastric and ileal segments in the anesthetized rat. Concentrations of solutes and a volume marker were periodically determined in the perfusate and net solute flux was calculated. RESULTS: The stomach secretes less sodium and very little bicarbonate in comparison with ileum. Hydrogen ion and chloride are absorbed by ileum but secreted in large quantities by the stomach. Ammonium, potassium, and urea are absorbed by both segments but to a much lesser degree in the stomach. Overall, there was a net osmolar absorption by ileum, and a net secretion by the stomach. Both segments secrete water to a similar degree. CONCLUSIONS: These findings both suggest the mechanism of the hypochloremic metabolic alkalosis seen after urinary reconstruction with the stomach and provide insight into potential therapeutic approaches. Solute fluxes in both the stomach and the ileum are consistent with the known physiology of these segments.

Animals↗
PubMed1994

Disseminated histoplasmosis presenting as urinary tract obstruction in a renal transplant recipient.

Disseminated histoplasmosis occasionally involves the kidney, but the infection usually does not cause either urinary symptoms or a decrease in renal function. We present a case of disseminated histoplasmosis in a renal transplant recipient who presented with urinary obstruction in the allograft from a sloughed renal papilla infected with the fungus. At the same time the patient had chronic meningitis from Histoplasma capsulatum. The literature on renal involvement with histoplasmosis is reviewed.

Constriction, Pathologic↗
PubMed1994

Local recurrence of squamous cell carcinoma of the penis.

Given the excellent local control rates achieved with partial penectomy, it is important to consider laser treatment or radiation therapy of squamous cell carcinoma of the penis cautiously. Emotional issues surrounding preservation of a functional penis should not be allowed to compromise adequate therapy. On the other hand, some penile cancers undoubtedly can be managed adequately by techniques other than partial penectomy. The fundamental question is, then, how great a compromise laser treatment or radiation therapy introduces. In patients who present with bulky, long-neglected penile cancers, the point is moot: Partial or even total penectomy is indicated. However, other treatments are feasible in many patients, and an attempt at functional organ preservation should not be restricted simply to the rare small tumor. Lesions up to 2 cm in size can be controlled adequately without amputation. Because tumor grade correlates highly with depth of invasion, the presence of nodal metastasis, and survival, most poorly differentiated squamous cell tumors of the penis probably should be treated by amputation. As mentioned above, it may be several months after laser treatment or radiation therapy before local treatment failure is recognized. Although this is a concern, it probably does not ultimately result in therapeutic compromise in most patients. With most urologic cancers, local recurrence equates with the inability to cure the patient and, ultimately, death. With locally recurrent carcinoma of the penis, however, the situation can be salvaged by converting to partial penectomy. Thus, the patient compromises his chances for cure only if tumor dissemination occurs during the few months between the end of treatment and recognition of failure.

Brachytherapy↗
PubMed1993

Morphologic and functional alterations of intestinal segments following urinary diversion.

The current study was undertaken to determine the effect of chronic urinary diversion on both the morphology and absorptive function of intestine. Adult female Wistar rats (N = 8) underwent urinary diversion by interposing a 10-12 cm. segment of distal ileum between the bladder and sigmoid colon following urethral ligation. Control animals (N = 8) underwent sham laparotomies. Three months later, the diverted segment and a 10-12 cm. segment of distal ileum in control animals were studied. The intestinal segments were studied morphologically by both light microscopy and transmission electron microscopy. By using a previously reported in vivo intestinal perfusion model, the transport properties of the intestinal segments were examined. There were prominent and consistent morphological alterations in the diverted segments when compared with normal ileum. These changes consisted of marked mucosal atrophy evidenced by loss of microvilli with decreased villi-to-crypt ratio in diverted segments. Diverted ileum secreted more sodium and absorbed less chloride than normal ileum though this difference was not statistically significant. Water flux into the intestinal lumen was higher in diverted bowel (p = .06). The absorption of ammonium, potassium, and urea, as well as bicarbonate secretion, was the same in the diverted ileum as in normal ileum. There was also no significant difference in pH change or osmolar flux between the two groups. In conclusion, the results of this study indicate that despite morphological changes as a result of chronic exposure of urine, intestinal segments continue to transport urinary solutes similar to normal nondiverted segments. This represents the first convincing evidence that the reason for the low incidence of metabolic alterations following urinary diversion is not due to decreased absorptive capacity of the intestinal mucosa.

Animals↗
PubMed1993

Delayed rupture of type I posterior urethral injury: case report.

Type I posterior urethral injuries are a frequently noted but infrequently reported entity in the setting of pelvic fracture. Almost all of these injuries will do well with Foley catheter drainage. However, the urethral integrity as established by admission retrograde urethrography is not an unalterable state and serious septic sequelae may be noted if the evolving injury is unrecognized. We report a case of delayed rupture of a type I posterior urethral injury causing infection of the pelvic hematoma and subsequent sepsis.

Accidents, Traffic↗
PubMed1992

Mechanism of ammonium transport by intestinal segments following urinary diversion: evidence for ionized NH4+ transport via K(+)-pathways.

Using a previously reported in vivo intestinal perfusion model in the rat, we have shown that net total ammonium absorption accounts for the majority of the acid load resulting from urinary intestinal diversion. In the present study, by varying perfusate pH and therefore NH3 concentrations, we demonstrated that the net flux of total ammonium did not correlate with non-ionized NH3 concentrations (r = .039). This indicates that the basic mechanism of total ammonium flux is via ionized NH4+ movement. To more precisely define the transport processes involved, we manipulated this system with the following chemical and pharmacologic probes of electrolyte transport: amiloride (0.5 mM/l.), furosemide (1 mM/l.), 2,4,6-triaminopyrimidine (TAP) (15 mM/l.), methylprednisolone (3 mg./100 gm./B.W.) S.Q. x 3 days followed by perfusion, and barium (Ba2+) (15 mM/l.). Net solute flux was not significantly altered by the mucosal addition of amiloride or TAP. Methylprednisolone treated rats exhibited significantly diminished Na+ secretion (p less than .01) and increased Cl- absorption (p less than .05) without affecting net total ammonium flux providing evidence for the inducibility of Na+ conductance channels and against significant NH4+ movement via this pathway. The mucosal addition of furosemide resulted in significantly decreased net absorption of both total ammonium (p less than .001) and K+ (p less than .05). The addition of Ba2+ resulted in a three-fold reduction of ammonium absorption (p less than .001) and a greater than ten-fold reduction in K+ absorption (p less than .001). The observation of significant inhibition of ammonium absorption by furosemide and barium suggests that K+ transport pathways play a significant role in the intestinal transport of NH4+.

Acidosis↗
PubMed1992

Mechanism of ammonium transport: inhibition by potassium and barium.

Elucidating the precise mechanism of intestinal ammonium transport is critical to the understanding of the acidosis associated with intestinal urinary diversion. Unfortunately, it is incompletely understood and controversial. Recently, we have shown that furosemide and Ba2+ significantly inhibit ammonium absorption in the ileum. On the basis of this and other data, we have suggested that ionized ammonium absorption occurs via K(+)-transport pathways. The present study examines intestinal ammonium absorption and its inhibition by K+ and Ba2+ utilizing a simplified in vivo system in rat distal ileum. Ammonium absorption demonstrates a tendency towards saturation at initial concentrations between 0 and 300 mM/l. Above 300 mM/l. there was a marked increase in ammonium absorption suggesting a possible biological effect of high NH4+ concentrations on the intestinal segment. Potassium inhibits ammonium absorption. K+ (50 mM/l.) significantly inhibited ammonium at an initial concentration of 100 mM/l. (p less than 0.05) and K+ (100 mM/l.) inhibited ammonium absorption at both 50 and 100 mM/l. (p less than 0.05 and p less than 0.01 respectively). Potassium inhibition of ammonium absorption was lost at concentrations above 200 mM/l. suggesting that K+ inhibition occurs via a competitive mechanism. Ba2+ (25 mM/l.) was shown to be a potent inhibitor of ammonium absorption. This significant inhibition persisted at high initial ammonium concentrations suggesting a complex, noncompetitive mechanism of inhibition. In conclusion, this study provides important data further suggesting that ammonium transport in the intestine occurs via K+ transport pathways, and suggests that the traditionally held mechanism of nonionic ammonium diffusion needs reevaluation.

Animals↗
PubMed1992

Immediate management of prostatomembranous urethral disruptions.

We present 33 patients with complete prostatomembranous urethral disruptions: 20 were managed by immediate realignment, while 13 were managed by initial cystotomy and delayed urethroplasty. Techniques for immediate realignment are described. Immediate realignment of complete prostatomembranous disruptions resulted in an overall potency rate of 80% compared to only 50% in patients who underwent delayed repair. In addition, there was an increased need for a secondary operation when the repair was delayed. Continence rates were excellent and similar in both groups. Immediate urethral realignment as described results in impotence and incontinence rates that are comparable to or better than delayed repair techniques without the need for multiple surgical procedures.

Adolescent↗
PubMed1992

Long-term metabolic effects of urinary diversion: a comparison of myelomeningocele patients managed by clean intermittent catheterization and urinary diversion.

We previously reported that chronic urinary diversion through intestinal segments may have adverse effects on bone and mineral metabolism. This study examined the long-term health of patients managed by urinary diversion (94% by ileal conduit) for neuropathic bladders secondary to myelomeningocele defects and compared them to a control population of myelomeningocele patients managed by intermittent catheterization. Of the patients 93 were studied by personal interview, chart review, morphometric analysis, serum studies and dual-photon bone density determination. Average followup was 23 +/- 6 years in the urinary diversion group and 17 +/- 5 years in the intermittent catheterization group. Fractures occurred in 40% of the patients in both groups. Patients with a urinary diversion had an increased need for surgery to correct spinal curvature (57% versus 40%) and a significantly increased incidence of complications resulting from orthopedic procedures (17% versus 3%, p less than or equal to 0.05). There was also an adverse effect on renal function. The urinary diversion group had an increased incidence of radiographic renal deterioration (57% versus 8%, p less than 0.001), nephrolithiasis (43% versus 2%, p less than 0.001), pyelonephritis (60% versus 21%, p less than 0.001) and intermittent metabolic acidosis (20% versus 5%, p = 0.05). Surgery was required in 37% for stomal complications and in 17% for ureterointestinal stricture. Linear growth was adversely affected by urinary diversion. Patients with urinary diversion had decreased lengths for all morphometric parameters and a greater percentage of them were at or below the 10th percentile standards. Serum electrolytes, liver function studies, vitamin D3 and parahormone showed no differences in the 2 groups. No patient had a significant metabolic acidosis at the time of study. Bone densities were significantly diminished in both groups and not significantly different. This study strongly suggests that urinary diversion through intestinal segments is associated with adverse effects on bone health.

Bone Density↗
PubMed1991

Urease and the acidosis of urinary intestinal diversion.

Previous investigators have suggested that urinary tract infections with urea-splitting organisms may be a primary etiologic factor in the acidosis which is seen after urinary diversion. This study employs a model in which small intestinal segments are perfused with an artificial urine solution over a three hour period. Urease is then added in order to determine its effect on acid-base balance and net intestinal electrolyte transport. Urease created no significant increase in acid load (delta HCO3- = -7.5 +/- 2.2 for controls vs. -8.7 +/- 2.9 for urease group), but did increase the osmolality of the intestinal contents and resulted in a 24% increase in free water loss (p = .037). Analysis of sodium and chloride movement following the addition of urease to the perfusate suggests that both ammonium and bicarbonate are absorbed by the intestinal segment. Thus any acidosis resulting from increased ammonium absorption following the addition of urease appears to be offset by concomitant bicarbonate absorption. The azotemia of urinary diversion appears to be primarily the result of urea absorption, partially the result of ammonium absorption, and is not significantly increased by urease.

Acid-Base Equilibrium↗
PubMed1991

Mechanisms of solute transport following urinary diversion through intestinal segments: an experimental study with rats.

This investigation employs an in vivo intestinal perfusion model in rats in order to study the mechanisms of intestinal electrolyte transport as it relates to the acidosis associated with urinary diversion. This investigation demonstrates that urinary ammonium is directly related to net sodium secretion and that chloride absorption is directly related to net bicarbonate secretion. The general mechanisms described are consistent with previously described mechanisms of intestinal electrolyte transport but demonstrate substantial differences in net directional movements compared to normal intestinal transport. This study provides a working model for further investigation and solutions to the management of the acidosis associated with urinary diversion.

Acidosis↗
PubMed1991

Management of primary nonrenal parenchymal malignancies with vena caval thrombus.

We report our experience with the management of 7 primary nonrenal parenchymal malignancies with vena caval tumor thrombus. Included are 3 cases of adrenal cortical carcinoma and 1 each of transitional cell carcinoma, embryonal cell testicular carcinoma, pheochromocytoma and primary small cell carcinoma of the lung with metastases to the kidney. Surgical treatment and followup are presented, as well as a review of the literature. An aggressive surgical approach is warranted because prolonged survivals free of disease are possible.

Adrenal Cortex Neoplasms↗