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SummaryClinical fatigue failure of 6 mm diameter interlocked nails (ILN) with holes accommodating 3.5 mm screws has been reported. This problem was investigated by testing eight different designs of 6 mm and 8 mm diameter ILN with a 2 plus 2 screw hole pattern and a multiple holed pattern. Interlocking nails with holes to accommodate 3.5 and 4.5 mm screws in 8 mm ILN and 2.7 and 3.5 mm screws in 6 mm diameter ILN were used. A rotating beam testing device produced uniform bending moments across a test region of the ILN containing at least two holes. These moments fully reversed with each cycle. Fatigue failure occurred through screw holes. Using statistical modeling, reduction of the 6 mm ILN hole size from accommodating 3.5 screws to 2.7 mm screws increased the estimated fatigue life (EFL) of the latter by 52 times, comparable to the EFL of the 8 mm ILN with 4.5 screw holes. Reducing the 8 mm ILN screw hole size from accommodating 4.5 screws to 3.5 mm screws increased the comparative EFL by eight times. Fatigue testing is a good method to compare fatigue behavior of various implant designs. This gives a surgeon more information when selecting an ILN for fracture fixation.Occasional breakage of interlocking nails (ILN) in clinical cases prompted fatigue testing of original ILN and new designs of ILN. This study documented base line fatigue resistance information of the various ILN designs. Results indicated smaller screw holes markedly increased the fatigue resistance of both 6 mm and 8 mm diameter ILN. This information will aid the surgeon in planning fracture treatment.

SummaryFemoral capital physeal fractures have been successfully repaired with 7.0 mm stainless steel cannulated screws. The holding power of 7.0 mm stainless steel cannulated screws, 8.0 mm stainless steel cannulated screws and 8.0 mm titanium cannulated screws was compared. The 8.0 mm titanium cannulated screw had the highest holding power, the 7.0 mm stainless steel cannulated screw was intermediate and the 8.0 mm stainless steel cannulated screw had the lowest holding power.When placed in the bovine femoral head, 8.0 mm titanium cannulated screws have holding power greater than 8.0 mm stainless steel cannulated screws. A 7.0 mm stainless steel cannulated screw has intermediate holding power.

Metacarpal shaft fractures are common injuries that frequently unite with some shortening of the metacarpal. The aim of this study was to determine the effect of metacarpal shortening on digital flexion force. The index metacarpal of six cadaveric upper limbs was incrementally shortened. The flexion force produced at the end of the finger was recorded using a small load cell. At full extension, there was no significant change in flexion force produced regardless of the amount of shortening. However, at 50% aggregate flexion the loss of force became statistically significant at a shortening of 7.5 mm or more. At full digital flexion, the loss of force became statistically significant at shortening of 5 mm or more. At increasing amounts of finger flexion, progressive metacarpal shortening produces proportionally greater loss of fingertip flexion force. From this study it appears that metacarpal shortening of up to 5 mm should give minimal loss of finger flexion force.

The idiopathic inflammatory bowel diseases, ulcerative colitis and Crohn's disease, are chronic disorders that appear to arise from an aberrant interaction of environmental, genetic, and immunologic factors. The aim of this study was to examine the immune reactivity of a spontaneously colitic mouse strain, C3H/HeJBir, to epithelial, food, and enteric bacterial Ags. Serum Ab responses of colitic C3H/HeJBir and noncolitic parental C3H/HeJ mice were measured by enhanced chemiluminescence Western blotting. No reactivity to epithelial or food Ags was detected. However, the sera from C3H/HeJBir mice had a reproducible banding pattern on Western blot to bacterial Ags, whereas sera from C3H/HeJ mice did not. Only a small, highly selected number of enteric bacterial Ags were recognized. There were major differences in the degree of recognition of different bacterial strains, marked by remarkably few Abs to Ags of the major anaerobes of the bacterial flora. The serum Abs detected on immunoblot were primarily IgG2a, suggesting a Th1 response. Comparison of sera reactivity to histopathologic severity showed an inverse relationship: one third of young C3H/HeJBir mice during the peak of colitis produced Abs to bacterial Ags, while later in life, when the colitis had resolved, 96% produced Abs. These data are consistent with an abnormal immune reactivity to enteric bacterial flora in C3H/HeJBir mice, a reactivity that is highly selective considering the abundant bacterial Ags present in the colon lumen. We postulate that this reactivity plays a role in the pathogenesis of colitis in these mice.

A novel affinity system for a two-phase delivery of radionuclides to tumor cells has been developed. In the first phase, a nontoxic bivalent monoclonal antibody conjugated to an enzyme is targeted to the tumor cells. In the second phase, a radionuclide-derivatized enzyme inhibitor, specific for the enzyme conjugated to the antibody, is administered. The model system selected for this study is the recombinant human enzyme dihydrofolate reductase (rhDHFR) and its high-affinity competitive inhibitor methotrexate (MTX). MTX was labeled with a radionuclide by covalent attachment of diethylenetriaminepentaacetic acid (DTPA) complexed with 111In. Using the gamma-carboxyl residue of MTX for the attachment of DTPA, binding of the inhibitor to rhDHFR was not affected. The inhibitory activities of nonderivatized MTX and DTPA-MTX were indistinguishable. Human K562 erythroleukemia cells were used to evaluate under in vitro conditions the DHFR-MTX affinity system for the delivery of 111In-labeled DTPA-MTX to pretargeted alpha-transferrin receptor antibody-rhDHFR conjugates (alpha-TFR-DHFR). The data demonstrate that the delivery of 111In is dose dependent and highly specific. Under saturating conditions, binding of 111In-DTPA-MTX to alpha-TFR-DHFR-treated cells was 14-fold higher than to cells treated with nonconjugated alpha-TFR antibody. Further experiments indicated that the low level of nonspecific binding of 111In-DTPA-MTX was comparable to that of 111In-DTPA, known for its complete extracellular distribution and rapid clearance through the kidneys. Based on the data of this study, antibody-conjugated rhDHFR and radionuclide-labeled DTPA-MTX complexes provide components for an alternative radioimmunotherapeutic approach that can be expected to result in improved tumor tissue ratios of both the targeting moiety and the radionuclide-labeled derivative as compared to current approaches.

A review of recent findings concerning enamel carious lesions is presented. This lesion represents the initial phase of dental caries and is characterized by a demineralization of the subsurface enamel caused by acids of the plaque bacteria. Streptococcus mutans has been described as the etiologic agent of the dental caries and the most acidogenic plaque bacteria. Morphological studies have shown an invasion of microorganisms inside the enamel carious lesion. Unfortunately, several technical problems are associated with such studies. The identification of the invading bacteria has not yet been achieved. The future identification of bacteria inside the subsurface enamel lesions will represent an important step in the prevention of the carious progression.

Over the past 15 years there has been a substantial effort to develop the potential of monoclonal antibody technology into medical applications. Significant progress has been made, especially in in vitro applications where the superiority of monoclonal antibodies over polyclonal antibodies is undisputed. In vivo success has been achieved in the detection of malignant (1,2) and cardiovascular diseases (3,4) with additional applications in locating deep tissue sites of bacterial infection being identified and developed (5). In colon cancer (2) and malignant melanoma (6) accuracy of tumor detection exceeds 80 percent and, for at least some anatomical sites, tumor detection with radiolabeled monoclonal antibodies is more sensitive than other detection methods (7,8). Within a short time, radiolabeled monoclonal antibodies have achieved a niche in the management of a few types of cancer where the information obtained complements that obtained by other methods and contributes to the effective management of these cancer patients. However, a host of technological difficulties continue to generate questions as to how broadly the monoclonal antibody niche is likely to develop in future years.

Melanoma-associated antigens (MAA) were isolated and their functional immunologic properties were evaluated. Spent fetal calf serum-free culture media and 3-m KCI extracts of cultured human melanoma cells grown in this medium were used as antigen sources. Ultracentrifugal flotation on KBr was used to separate MAA and HLA antigens present in the extracts or spent culture media; thus interference by histocompatibility antigens was prevented in subsequent tests of tumor antigenic activity. MAA purified in this manner retained their immunologic functions as evidenced by their ability to produce delayed cutaneous hypersensitivity reactions in patients with melanoma, specifically combine with antimelanoma xenoantibody, and elicit production of functionally specific xenoantibody. Possible structural differences between HLA antigens and MAA were considered in evaluation of the data.

Carcinoembryonic antigen (CEA) activity was assayed in plasma and in pure pancreatic juice from eight patients with carcinoma of the pancreas, 28 patients with pancreatitis, and 13 controls with no demonstrable pancreatic disease. Juice specimens were obtained via direct transduodenal cannulation of the pancreatic duct. The mean pancreatic juice CEA activities in controls, pancreatitis, and pancreatic carcinoma were 8.1 ng/ml, 18.6 ng/ml, and 309 ng/ml, respectively. Pancreatic juice CEA activity in patients with cancer of that organ was significantly higher than in those with pancreatitis or in controls. None of the 32 subjects with both pancreatic juice CEA activity less than 30 ng/ml and plasma CEA less than 2.5 ng/ml had pancreatic cancer. Three of the four patients with CEA elevations in both fluids above these levels harbored this malignancy. These findings suggest that combined measurement of CEA activity in plasma and pancreatic juice may help in diagnosing pancreatic disease.

Xenoantisera to human melanoma cells and to partially purified melanoma-associated antigens were coupled to protein A-bearing Staphylococcus Aureus or protein A-Sepharose and used as immunoadsorbents for the indirect immunoprecipitation of intrinsically radiolabeled proteins released into culture medium from various cultured human tumor and nontumor cell lines. These radiolabeled immunoprecipitates when analyzed by SDS-PAGE revealed highly reproducible molecular profiles of proteins and glycoproteins released by various cultured tumor lines and control cells into their spent culture media. A comparison of molecular profiles together with data indicating the binding specificity of known xenoantisera produced against human melanoma cells or their extracts led to the discovery of 2 macromolecules that are associated with human melanoma cells; a glycoprotein with a subunit m.w. of 240,000 (240K) and a single-chain glycoprotein of 94,000 (94K) m.w. also found in association with human carcinoma cells are described in this report.

The Paper describes an investigation into the actual flow patterns in granular fill during discharge from tall silos. The work was done with the aid of model silos of different sizes. Three separate gradings of fine gravel fill were tested for various port openings centrally located. Rough and smooth walled surfaces were used. Two independent methods for investigating the nature of flow were employed, namely gravel fill arranged in concentric cylinders of colour inside the model silo and, independently, radioactive labels placed in the fill tracked with an isotope scanner during discharge. The results of the investigation clearly revealed the flow patterns. The work also indicated that four separate zones of flow occur within the fill, namely a plug flow zone occurring at all levels above crater formation level, a dynamic equilibrium zone confined to that of a mitre-of-revolution formed over the central port opening within which the fill is in a steady state of deformation, a dead space zone confined to inert material forming a natural hopper bottom and a free-fall zone which occurs beneath the soffit of the mitre-of-revolution. This zone is of open texture where the particles of fill material accelerate freely. Cette Communication décrit une étude des profils d'écoulement réels dans des charges de particules au cours de la vidange de silos de grandes dimensions. On a effectué les études sur des modèles de silos de diverses dimensions. On a utilisé trois fractions granulométriques de remblais de gravillons pour diverses dimensions d'ouvertures centrales. On a également étudié l'influence de la rugosité des parois. On s'est servi de deux méthodes indépendantes pour étudier la nature de l'écoulement: une mise en place du matériau ensilé en cylindres concentriques colorés à l'intérieur de modèle, et, au cours d'autres expériences indépendantes, l'utilisation de traceurs radioactifs placés dans la masse, dont on a suivi le mouvement au cours de la vidange par balayage isotopique. Les résultats de ces études ont mis en évidence clairement le type d'écoulement existant. Ils démontrent également qu'il y a quatre zônes d'écoulement distinctes dans la masse: (a) une zône d'écoulement frontal qui existe à tous les niveaux supérieurs au niveau de formation du cratère, (b) une zône d'équilibre dynamique limitée par un cône de révolution à 45° passant par l'ouverture centrale, dans laquelle la masse est en état d'équilibre de déformation (c) une zône morte correspondant au matériau au repos formant un fonds incliné naturel d) une zône de chute libre située au-dessous du cône de révolution. Cette zône a une structure ouverte, dans laquelle les particules du matériau accélèrent librement.

Pancreatic juice collected from 10 patients without evidence of malignant disease of the pancreas or other organs was pooled, extracted, and fractionated by Sepharose 6-B and Sephadex G-200 gel filtration. The carcinoembryonic antigen (CEA) activity in the material was demonstrated and studied by: a) radioimmunoassay, b) competitive binding to antibodies against CEA, c) precipitin inhibition, and d) Ouchterlony analysis. The immunochemical identity of the active material to CEA purified from liver metastases of colon cancer was demonstrated.

A radioimmunometric antibody-binding assay was developed with the use of /sup 125/I-labeled protein A of Staphylococcus aureus (SpA) for the evaluation of xenoantisera to human melanoma-associated antigens. Antisera were produced in New Zealand male albino rabbits by the injection of cultured human melanoma cells or soluble, partially purified melanoma-associated antigens isolated from these cells. Xenoantisera were rendered operationally specific for melanoma-associated antigens by absorption with human red cells and cultured lymphoblasts. The methodologic parameters and the quantitative relationships among xenoantisera, cultured melanoma target cells, and /sup 125/I-labeled SpA and their effect on the measurement of xenoantibody binding were critically evaluated. Data indicated the usefulness of the radioimmunometric assay in monitoring the efficacy of absorption and in characterizing the specificity of xenoantisera to melanoma-associated antigens. The radioimmunometric binding assay when modified and used as a binding inhibition assay was effective in the assessment of the serologic activity of soluble melanoma-associated antigens and thus may be used to monitor the progress of antigen purification.

Serologic and immunochemical assays showed that human melanoma-associated antigens (MAA) identified with operationally specific xenoantisera were neither spatially nor structurally associated with beta 2-microglobulin (beta 2-mu), the light chain of the HLA-A,B antigen molecular complex; i.e., cultured melanoma cells coated with a specific anti-beta 2-mu xenoantiserum maintained their reactivity with anti-MAA xenoantisera. Furthermore, soluble MAA were not bound by a beta 2-mu immunoadsorbent. Finally, MAA were shed into the culture medium of melanoma cells and then were immunoprecipitated with specific anti-MAA xenoantisera, analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, they appeared as two distinct structures with molecular weights of 240,000 and 94,000 but comprised no structure with the characteristic 12,000 molecular weight of beta 2-mu. Conversely immunoprecipitates obtained by the reaction of spent culture medium of [3H]valine-labeled melanoma cells with anti-beta 2-mu xenoantiserum had the 12,000-molecular-weight component but no structures with the molecular weights established for MAA. Thus the data refute the contention that serologically detectable MAA have a molecular structure similar to that of HLA antigens.

A radioimmunometric antibody-binding assay was developed with the use of 125I-labeled protein A of Staphylococcus aureus (SpA) for the evaluation of xenoantisera to human melanoma-associated antigens. Antisera were produced in New Zealand male albino rabbits by the injection of cultured human melanoma cells or soluble, partially purified melanoma-associated antigens isolated from these cells. Xenoantisera were rendered operationally specific for melanoma-associated antigens by absorption with human red cells and cultured lymphoblasts. The methodologic parameters and the quantitative relationships among xenoantisera, cultured melanoma target cells, and 125I-labeled SpA and their effect on the measurement of xenoantibody binding were critically evaluated. Data indicated the usefulness of the radioimmunometric assay in monitoring the efficacy of absorption and in characterizing the specificity of xenoantisera to melanoma-associated antigens. The radioimmunometric binding assay when modified and used as a binding inhibition assay was effective in the assessment of the serologic activity of soluble melanoma-associated antigens and thus may be used to monitor the progress of antigen purification.

Neoantigen(s) induced on Syrian hamster cells during chemical carcinogenesis are also found on fetal and neoplastic hamster cells. 46 neoplastic cell lines independently isolated from colonies of 3-methylcholanthrene (3-MCA) in vitro-transformed hamster cells growing in semi-solid agar medium were assayed for expression of neoantigens recognized by hamster antisera to primary cultured late-term (15 days) hamster embryo cells treated for 18 h with 10 micrograms 3-MCA/ml. Ratios of the binding of this sera compared to solvent control sera ranged from 0.7 to 2.1 in terms of cpm bound. Only four of the 46 neoplastic cell lines exhibited significant (P less than 0.05) neoantigen expression. No correlation existed between the concentration of 3-MCA used to establish the neoplastic cell line and expression of the neoantigen(s). Absorption of the sera with these four highly reactive neoplastic cell lines and mid-term (10 days) embryo cells indicated that the neoantigen(s) recognized were common to the four reactive neoplastic cell lines and the mid-gestation fetal cells. The occurrence of early persistent immunogenic cell-surface alterations during in vitro carcinogenesis provides an approach to isolation of preneoplastic populations and provides potential target structures for the inhibition of carcinogenesis.

A cytokine that inhibits fibrinolysis has been detected in the serum-free culture medium of guinea pig and hamster fibroblasts. This proteinase inhibitor was also present in Triton X-100 extracts of guinea pig cells. It was stable at pH 3.0 for 2 hr and was produced by cells rather than assimilated from serum in the culture medium as evidenced by: (a) an apparent molecular size (less than 45 kilodaltons) less than that of the principal serum-derived proteinase inhibitors; (b) its continued secretion after several passages of the cells in serum-free medium; and (c) the lack of inhibitory activity in the medium of mitomycin C-treated cells. The cytokine inhibited the proteinase activity of human urokinase, soluble TPA-stimulated guinea pig plasminogen activator, and the cell-associated plasminogen activator of tumorigenic guinea pig cells. Soluble plasminogen activator appeared to be inhibited to a greater degree than the cell-associated enzyme. The fluorogenic substrate (7-(N-carbobenzoxyglycylglycylargininamido)-4-methylcoumarin was used in a direct assay of proteinase activity and demonstrated that the cytokine inhibited both plasminogen activator and plasmin, the two proteinases of the fibrinolytic cascade. Tumorigenic guinea pig and hamster fibroblasts as well as nontransformed guinea pig fibroblasts were found to produce the inhibitory cytokine, and the amount of inhibitor secreted was independent of the tumorigenic potential of the cells. Production of the inhibitor by normal cells may be related to contact inhibition of growth, and this cytokine may contribute to the fine regulation of local proteolysis within tissues.

The immunogenicity of inbred strain 2/N guinea pig fibroblasts transformed to the malignant state in vitro by chemical carcinogens was evaluated with the use of a variety of in vivo and in vitro methods including delayed-type hypersensitivity skin and tumor transplantation tests and analysis of antibody production by immunofluorescence, complement fixation, and staphylococcal protein A binding tests. Neoplastic transformation was induced by direct treatment of cells in culture with benzo[a]pyrene, 3-methylcholanthrene, or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or by the host-mediated method by which fetuses were exposed to diethylnitrosamine or MNNG in vivo prior to cell culture. Rabbits and syngeneic guinea pigs were inoculated with unirradiated and X-irradiated clonally derived cells. Delayed hypersensitivity skin reactions to immunizing or other cells were equivalent in immunized or control guinea pigs, and no protection to tumor outgrowth from a challenge inoculum of immunizing cells was observed. Antibody activity induced in the sera of immunized guinea pigs was cross-reactive and removed by absorption with nontumorigenic cells. Rabbit antisera after absorption with fetal guinea pig cells were nonreactive with the specific immunizing or other culture cells. Chemical carcinogen-induced neoplastic transformation of guinea pig cells can, therefore, occur without formation of detectable, individually distinct cell surface tumor-specific neoantigens.

Carcinoembryonic antigen (CEA) activity was assayed in plasma and in pure pancreatic juice from eight patients with carcinoma of the pancreas, 28 patients with pancreatitis, and 13 controls with no demonstrable pancreatic disease. Juice specimens were obtained via direct transduodenal cannulation of the pancreatic duct. The mean pancreatic juice CEA activities in controls, pancreatitis, and pancreatic carcinoma were 8.1 ng/ml, 18.6 ng/ml, and 309 ng/ml, respectively. Pancreatic juice CEA activity in patients with cancer of that organ was significantly higher than in those with pancreatitis or in controls. None of the 32 subjects with both pancreatic juice CEA activity less than 30 ng/ml and plasma CEA less than 2.5 ng/ml had pancreatic cancer. Three of the four patients with CEA elevations in both fluids above these levels harbored this malignancy. These findings suggest that combined measurement of CEA activity in plasma and pancreatic juice may help in diagnosing pancreatic disease.

Pancreatic juice collected from 10 patients without evidence of malignant disease of the pancreas or other organs was pooled, extracted, and fractionated by Sepharose 6-B and Sephadex G-200 gel filtration. The carcinoembryonic antigen (CEA) activity in the material was demonstrated and studied by: a) radioimmunoassay, b) competitive binding to antibodies against CEA, c) precipitin inhibition, and d) Ouchterlony analysis. The immunochemical identity of the active material to CEA purified from liver metastases of colon cancer was demonstrated.

The quantitative expression of five properties of chemical carcinogen-induced, neoplastically transformed NIH strain 2 guinea pig fibroblasts was compared in cells possessing thousandfold differences in tumorigenicity. Plasminogen activator synthesis, sensitivity to lymphotoxin inhibition of cell proliferation, and the ability to induce a natural delayed tuberculin-type skin reaction in nonimmune syngeneic guinea pigs correlated directly with the number of cells required to produce a tumor. The most tumorigenic cells (10(2)-cell threshold dose) produced the most plasminogen activator, were most sensitive to lymphotoxin, and produced the greatest skin reactivity. Cells with a threshold tumor dose of 10(5)-10(7) cells exhibited the lowest expression of these properties. Fibronectin incorporation into an extracellular matrix was diminished in tumorigenic cells, as was anchorage-dependent growth; but neither diminished fibronectin incorporation nor the decreased anchorage requirement correlated quantitatively with the number of cells required to produce a tumor. The present investigation indicates that plasminogen activator synthesis, sensitivity to lymphotoxin, and the capacity of tumorigenic cells to induce natural delayed-type skin reactivity are among the factors that influence initial tumor growth. Plasminogen activator, an extracellular protease, may aid in the growth and spread of tumor cells in vivo by interfering with host fibrin deposition and by inactivating other host proteins such as lymphotoxin.

We studied the pharmacokinetic properties of two human monoclonal antibodies to colon carcinoma cells and their ability to detect tumors in nude mice bearing primary human colon carcinoma xenografts. The 16-88 and 28A32 monoclonal antibodies are immunoglobulin M class human antibodies produced by cell lines derived from peripheral blood lymphocytes from patients with colon carcinoma. The patients received an autologous tumor cell vaccine as part of an active specific immunotherapy protocol. The 125I-labeled antibodies were cleared from the circulation of non-tumor-bearing and tumor-bearing nude mice with a 6-8-h half-life. The half-life of the antibodies in tumor tissue was 48 to 72 h compared to 8 to 12 h for normal tissues. Tumor:normal tissue ratios were highest 4 to 7 days postinjection with tumor:blood ratios of 12:1 for 16-88 and 10:1 for 28A32 antibody. Experiments with a control human immunoglobulin M myeloma protein confirmed the specificity of the human monoclonal antibodies. Radioimmunoscintigraphic studies using nude mice bearing contralateral antibody-reactive and nonreactive colon tumor xenografts further confirmed that the antibodies specifically localized in tumor tissues. The antibody-reactive tumors were clearly visible by radioimmunoscintigraphy within 4 days of injection. These experiments, undertaken as a preliminary step to clinical trials, demonstrated for the first time that i.v. administered human immunoglobulin M monoclonal antibodies could be taken up by human colon tumor tissue and retained to a sufficient extent to easily permit tumor detection by external radioimmunoscintigraphy. These studies also demonstrated that the nude mouse human colon tumor xenograft model is a useful in vivo system for comparison studies of human monoclonal antibodies as part of a selection process for clinical trials and for evaluating immunoconjugates containing these antibodies for relative pharmacokinetic properties and potential diagnostic or therapeutic efficacy.

Serologic and immunochemical assays showed that human melanoma-associated antigens (MAA) identified with operationally specific xenoantisera were neither spatially nor structurally associated with beta 2-microglobulin (beta 2-mu), the light chain of the HLA-A,B antigen molecular complex; i.e., cultured melanoma cells coated with a specific anti-beta 2-mu xenoantiserum maintained their reactivity with anti-MAA xenoantisera. Furthermore, soluble MAA were not bound by a beta 2-mu immunoadsorbent. Finally, MAA were shed into the culture medium of melanoma cells and then were immunoprecipitated with specific anti-MAA xenoantisera, analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, they appeared as two distinct structures with molecular weights of 240,000 and 94,000 but comprised no structure with the characteristic 12,000 molecular weight of beta 2-mu. Conversely immunoprecipitates obtained by the reaction of spent culture medium of [3H]valine-labeled melanoma cells with anti-beta 2-mu xenoantiserum had the 12,000-molecular-weight component but no structures with the molecular weights established for MAA. Thus the data refute the contention that serologically detectable MAA have a molecular structure similar to that of HLA antigens.

An enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody was developed to determine the clinical value of urinary fibrinogen/fibrin degradation product levels for the identification and management of patients with bladder cancer. Assays were performed on 286 serial urine specimens from 56 bladder carcinoma patients. Specimens were grouped according to whether the patient had an evident tumor at the time of specimen collection (134 specimens, 41 patients) or was clinically disease-free following treatment (152 specimens, 38 patients). Many patients contributed specimens to both groups as determined by their clinical status at the time of collection. In addition, 45 specimens from 33 patients with inflammation of the urogenital tract and 81 specimens from 19 patients with renal or prostatic cancer were assayed for urinary fibrin degradation products. The ELISA, using a high-sensitivity procedure, identified 83% of the specimens from bladder cancer-positive patients with an overall accuracy with all specimens of 78% and a false-negative rate of 5% for all specimens tested. The high-sensitivity ELISA appeared most appropriate for monitoring bladder cancer patients for recurrence of tumor after surgery. The ELISA using a high-specificity procedure appeared most appropriate for screening. The high-specificity ELISA accurately identified 96% of urine specimens from non-bladder cancer patients with a false-positive rate of only 5%. These results demonstrate that the ELISA is an efficient, reliable, quantitative, and noninvasive immunoassay that can be useful both for the identification of bladder cancer patients and for monitoring the course of the disease.

During the last decade, there has been an increasing amount of evidence indicating that the neoplastic state is characterized by cell-surface changes, and this development has led to a concerted effort by many investigators to characterize cell-surface markers associated with human tumor cells. This research effort was further stimulated by the anticipation that the thorough characterization of human tumor markers may aid in the delineation of neoplastic transformation and advance the development of immunological approaches for diagnosis, prognosis, and thereapy of cancer. In this regard, the finding of antigens that are shed into the extracellular environment of tumor cells has received considerable attention (Grimm et al., 1976; Bystryn, 1977; McCabe et al., 1978; Gupta et al., 1979; Galloway et al., 1981a), since it may further aid in the development of approaches designed to improve detection and therapy of cancer.

Melanoma-associated antigens (MAA) were isolated and their functional immunologic properties were evaluated. Spent fetal calf serum-free culture media and 3-m KCI extracts of cultured human melanoma cells grown in this medium were used as antigen sources. Ultracentrifugal flotation on KBr was used to separate MAA and HLA antigens present in the extracts or spent culture media; thus interference by histocompatibility antigens was prevented in subsequent tests of tumor antigenic activity. MAA purified in this manner retained their immunologic functions as evidenced by their ability to produce delayed cutaneous hypersensitivity reactions in patients with melanoma, specifically combine with antimelanoma xenoantibody, and elicit production of functionally specific xenoantibody. Possible structural differences between HLA antigens and MAA were considered in evaluation of the data.