Generation of a monoclonal antibody (G9) reactive with an organ-specific, tumor-associated epitope of human colon carcinoma.

A monoclonal antibody (G9), having an organ-specific and tumor-associated reactivity with colon carcinoma, has been generated. Monoclonal antibody G9 is an IgG1 immunoglobulin produced by immunization of mice with mucin which had been purified from a liver metastasis of a moderately differentiated human colon carcinoma. Examination of normal adult tissues, by enzyme immunoassay and immunohistochemical procedures, showed the G9-reactive epitope to be restricted to the gastrointestinal tract. Within the gastrointestinal tract the colon produced the highest amount of the epitope. A sharp, decreasing gradient of reactivity was observed, ending in the small intestine. Although the normal colonic epithelium did produce the G9-reactive determinant, there was a significant quantitative increase of the epitope in neoplastic colonic tissue; mucins derived from normal colon contained less than 10% of the specific epitope as compared with mucins derived from colon cancer tissues (P less than 0.01). In addition, a tumor xenograft contained 100 times the amount of epitope as did normal colonic tissue. By immunohistochemical procedures 70% of all colon carcinomas were positive. A relationship with differentiation was noted, with 80% of well differentiated and 83% of moderately differentiated tumors being positive, whereas only 1 of 6 poorly differentiated tumors were stained. The organ specificity was noted in neoplastic as well as normal tissues. Monoclonal antibody G9 was nonreactive with breast, lung, and ovarian tumors. The data suggest that at the level of sensitivity obtained by the immunoassays used, and within the range of tissues examined, monoclonal antibody G9 is organ specific and highly tumor associated in its reactivity.

Organ specific antigens of the human gastrointestinal tract.

We previously reported the characterization of a normal adult colonic mucin antigen which contained an organ specific immunodeterminant [Tissue Antigen 11, 362 (1978)]. In the present study we have investigated mucins produced at other levels of the gastrointestinal tract in order to determine if regional specificities exist. Mucins were isolated from normal adult stomach, jejunum, ileum and colon and used to prepare antisera in rabbits. By radioimmunoassay at least four distinct specificities were observed. Gastric, ileal and colonic mucins were shown to contain immunodeterminants which were organ specific. Antiserum directed toward jejunal mucin determinants was reactive with the entire gastrointestinal tract. However, by heterologous inhibition analyses employing purified mucins as inhibiting antigens, the anti-jejunum antiserum was shown to be capable of discriminating a determinant present in much higher epitope density within small intestinal mucins as compared to mucins of the stomach and colon. Thus, it appeared that immunologic determinants present within mucin type glycoproteins of the gastrointestinal tissues exhibit anatomic specificity. In each case the structure of the immunodeterminant was, or was dependent upon the presence of a sialic acid derivative.

Effects of combination cyclosporine/mizoribine immunosuppression on canine renal allograft recipients.

Heterotopic renal allografts following bilateral nephrectomies were placed in 21 healthy mongrel dogs. One group of 11 dogs received cyclosporine (5 mg/kg/24 hr, orally), and 1 group of 10 dogs received cyclosporine and mizoribine (5 mg/kg and 3 mg/kg/24 hr, orally). Body weights, blood cell counts, serum chemistry profiles, serum electrolyte levels, urinalysis with cytology and culture, lymphocyte stimulation assays, immunoglobulin levels, whole blood levels of cyclosporine, and serum levels of mizoribine were followed. At the end of each survival period, necropsy and histopathologic examinations were performed. The mean survival time for the cyclosporine group was 12.8 +/- 7 days. The mean survival time for the cyclosporine/mizoribine group was 33.6 +/- 16.4 days, significantly longer (P = .0006) than the cyclosporine group. Death in the cyclosporine/mizoribine group was attributed to the combined effects of renal allograft rejection and development of a mizoribine-dependent enteritis. Serum levels of mizoribine were greater in the last half of the survival period due to compromised renal excretion of the drug. There were no complications due to infection, myelosuppression, or hepatotoxicity. Combination cyclosporine/mizoribine immunosuppression enhanced canine renal allograft survival in this study. Monitoring serum concentrations of mizoribine is imperative to determine toxic (enteritis) levels. Availability of an intravenous form of mizoribine would facilitate immunoregulation during periods of variable intestinal absorption or renal excretion.

Effects of mizoribine on canine renal allograft recipients.

Heterotopic renal allograft transplantation and bilateral nephrectomies were performed on 12 mixed-breed dogs. Histoincompatibility was confirmed by serologically defined and lymphocyte-defined antigen testing. Mizoribine (5 mg/kg, q 24 h) was administered orally starting the day of surgery. Body weights, blood cell counts, serum biochemical and electrolyte values, immunoglobulin concentration, and serum mizoribine concentrations were determined. Complete urinalyses, including bacteriologic culturing and lymphocyte stimulation assays were performed. The mean survival time for the allograft recipients was 20 +/- 14 days; significantly longer than nontreated historic controls surviving 8.1 +/- 0.6 days (P = 0.0098). Death was attributed to the combined effects of renal allograft rejection and development of a mizoribine-dependent gastroenteritis. Serum mizoribine concentrations were greater in dogs undergoing rapid allograft rejection because of compromised renal excretion of the drug. This resulted in a rapid onset of gastroenteritis. There were no complications resulting from infection, myelosuppression, or hepatotoxicosis.

Renal tubular acidosis in two horses: diagnostic studies.

An 11-year-old Quarter Horse mare and a 2-year-old Quarter Horse colt with clinical diagnoses of renal tubular acidosis (RTA) were donated to the University of California Veterinary Medical Teaching Hospital. A series of diagnostic tests was performed in an attempt to characterize the type and cause of RTA in these horses. Endogenous creatinine clearance and sodium sulfanilate clearance were within reference ranges; thus, no abnormality of glomerular function was detected. To assess renal tubular function in response to acid loading, each horse was given 0.1 g of NH4Cl/kg of body weight via nasogastric tube in 6 L of water. Urine acidification in response to the oral acid load was less than that observed in control horses. The urinary clearance ratio for sodium also was found to be greater for the principals than for the controls. These findings supported a diagnosis of RTA that closely resembled type 1 or distal RTA. In an attempt to determine the cause of RTA, renal ultrasonography, renal biopsy, and a mating study were performed. No abnormalities were identified, and the cause of RTA in these cases remained unknown.

Comparative nephrotoxicity of gentamicin and netilmicin: functional and morphological correlations with urinary enzyme activities.

An increase in urinary enzyme activities reflected biopsy confirmed aminoglycoside nephrotoxicity (proximal tubular injury) before changes in blood urea nitrogen, serum creatinine, urinary osmolality and urinary protein excretion. Netilmicin, a semisynthetic derivative of gentamicin, was less nephrotoxic than gentamicin.

Furosemide enhancement of experimental gentamicin nephrotoxicity: comparison of functional and morphological changes with activities of urinary enzymes.

Dogs were given gentamicin (10 mg/kg) intramuscularly every 8 hr for 10 days. Levels of serum creatinine rose by day 6 (0.91 +/- 0.08 vs. 0.75 +/- 0.02 mg/dl for controls, P less than 0.05) and of blood urea nitrogen by day 8 (24.3 +/- 4.80 vs. 16.1 +/- 0.90 mg/dl for controls, P less than 0.05). Gentamicin nephrotoxicity occurred earlier and was more marked when furosemide (2 mg/kg) was added: the level of serum creatinine by day 6 was 1.62 +/- 0.25 mg/dl (P less than 0.05), and the level of blood urea nitrogen by day 8 was 181 +/- 23.5 mg/dl (P less than 0.01). Elevations in the activities of the urinary enzymes beta-glucuronidase, N-acetyl-beta-glucosaminidase, and muramidase preceded rises in levels of serum creatinine and blood urea nitrogen. Examination of serial percutaneous renal biopsy specimens showed that gentamicin administration was associated with hyaline droplet degeneration, lysosomal changes, and, later, cell necrosis (primarily of the proximal tubules). Changes in renal morphology were more severe and occurred earlier when furosemide was administered concomitantly. In summary, furosemide enhanced gentamicin nephrotoxicity. Enzymuria was an early sign of gentamicin nephrotoxicity.

Effects of intravenous infusion of doxorubicin on blood chemistry, blood pressure and heart rate in rabbits.

The effects of a 1 h continuous infusion of doxorubicin (12.5 mg kg-1, 200 mg M-2) on blood chemistry was examined in rabbits over a 6-h period. Plasma glucose levels remained unchanged while insulin levels were significantly decreased to 39, 45 and 61% of the zero time value (12.8 +/- 2.9 ng ml-1) at 30, 60 and 120 min, respectively, after starting the drug infusion. Plasma cortisol levels were increased to 141, 140 and 131% of the initial zero time value (12.3 +/- 2.2 ng ml-1) at 120, 240 and 360 min, respectively. Doxorubicin had no effect on plasma electrolytes, osmolality and urea nitrogen but significantly increased plasma creatinine over the corresponding control value (2.2 +/- 0.8 micrograms ml-1 to 4.9 +/- 0.7 micrograms ml-1) at 120 min and the level remained elevated for the remaining period of the study. Systolic and diastolic pressure, and heart rate were also depressed at 240 and 360 min. The data collected in the present study indicate that the doxorubicin infusion might have a direct effect on beta cells in the pancreas as well as muscle tissue. Changes in cortisol, blood pressure and heart rate appear to be secondary to other effects produced by doxorubicin.