Model of charge transfer collisions between C60 and slow ions.

A semiclassical model describing the charge transfer collisions of C60 fullerene with different slow ions has been developed to analyze available observations. These data reveal multiple Breit-Wigner-like peaks in the cross sections, with subsequent peaks of reactive cross sections decreasing in magnitude. Calculations of charge transfer probabilities, quasi-resonant cross sections, and cross sections for reactive collisions have been performed using semiempirical interaction potentials between fullerenes and ion projectiles. All computations have been carried out with realistic wave functions for C60's valence electrons derived from the simplified jellium model. The quality of these electron wave functions has been successfully verified by comparing theoretical calculations and experimental data on the small angle cross sections of resonant C60+C60 + collisions. Using the semiempirical potentials to describe resonant scattering phenomena in C60 collisions with ions and Landau-Zener charge transfer theory, we calculated theoretical cross sections for various C60 charge transfer and fragmentation reactions which agree with experiments.

Solid-state culture of Azospirillum brasilense: a reliable technology for biofertilizer production from laboratory to pilot scale.

A biofertilizer of Azospirillum brasilense was produced in solid-state culture (SSC) from laboratory to pilot scale. Similar operation conditions (continuous aeration and mild intermittent mixing) and two dimensionless numbers with similar L/D ratio and a similar working volume were applied to reach a scale-up factor of 75. An innovative bioreactor with rotating helical ribbons (15 kg wet matter) was used at pilot scale. A mathematical model was proposed and validated to evaluate the respirometry trends at laboratory and pilot scale exhibiting similar behavior. The cell viability was (1.3 ± 0.4) × 109 and (1.3 ± 0.3) × 109 colony-forming units per gram of initial dry mass at laboratory and pilot scale, at 36 and 43 h, respectively. A. brasilense maintains its viability twelve months of storage at 4 and 30 °C. This is the first report of A. brasilense being cultivated in SSC under controlled conditions. SSC processes involving unicellular microorganisms with tolerance to agitation are a promising technology to produce biofertilizers.

Rydberg Electrons in a Bose-Einstein Condensate.

We investigate a hybrid system composed of ultracold Rydberg atoms immersed in an atomic Bose-Einstein condensate (BEC). The coupling between Rydberg electrons and BEC atoms leads to excitations of phonons, the exchange of which induces a Yukawa interaction between Rydberg atoms. Because of the small electron mass, the effective charge associated with this quasiparticle-mediated interaction can be large. Its range, equal to the BEC healing length, is tunable using Feshbach resonances to adjust the scattering length between BEC atoms. We find that for small healing lengths, the distortion of the BEC can "image" the Rydberg electron wave function, while for large healing lengths the induced attractive Yukawa potentials between Rydberg atoms are strong enough to bind them.

Tuning ultracold chemical reactions via Rydberg-dressed interactions.

We show that ultracold chemical reactions with an activation barrier can be tuned using Rydberg-dressed interactions. Scattering in the ultracold regime is sensitive to long-range interactions, especially when weakly bound (or quasibound) states exist near the collision threshold. We investigate how, by Rydberg dressing a reactant, one enhances its polarizability and modifies the long-range van der Waals collision complex, which can alter chemical reaction rates by shifting the position of near-threshold bound states. We carry out a full quantum mechanical scattering calculation for the benchmark system H(2)+D, and show that resonances can be moved substantially and that rate coefficients at cold and ultracold temperatures can be increased by several orders of magnitude.

Quantum Hall to charge-density-wave phase transitions in ABC-trilayer graphene.

ABC-stacked trilayer graphene's chiral band structure results in three (n=0, 1, 2) Landau level orbitals with zero kinetic energy. This unique feature has important consequences on the interaction-driven states of the 12-fold degenerate (including spin and valley) N=0 Landau level. In particular, at many filling factors ν(T) = ±5, ±4, ±2, ±1 a quantum phase transition from a quantum Hall liquid state to a triangular charge-density wave occurs as a function of the single particle-induced Landau level orbital splitting Δ(LL). Experimental signatures of this phase transition are also discussed.

Detection of cell surface and intracellular antigens by human monoclonal antibodies. Hybrid cell lines derived from lymphocytes of patients with malignant melanoma.

This study represents an initial attempt to analyze the humoral immune reactions of patients with malignant melanoma by hybridoma methodology. Using lymphocytes from regional lymph nodes, peripheral blood and tumor infiltrates, 158 fusions were performed with SKO-007 (human myeloma line), LICR-LON-HMy2 (LICR-2), GM 4672 (human lymphoblastoid lines), or NS-1 (mouse myeloma line). Fusion of lymph node lymphocytes with NS-1 resulted in a 3-4 times higher frequency of clones than fusion with LICR-2, and a 10 times higher frequency than fusion with SKO-007 or GM 4672. In the case of peripheral blood lymphocytes, fusion with NS-1 gave greater than 25 times higher frequency of clones than fusion with LICR-2 or SKO-007. Production of human mu, gamma, or alpha heavy chains was detected in 50-80% of wells containing growing clones, and the levels of immunoglobulin ranged from 0.3 micrograms to 40 micrograms/ml. NS-1-derived clones could be easily subcultured, while LICR-2 and SKO-007 clones grew more slowly on subculturing. In this study, Ig secretion appeared to be a more stable property of LICR-2-derived clones than NS-1-derived clones. A panel of 20 human cancer cell lines was used to screen 771 Ig-secreting cultures for antibody to cell surface or intracellular antigens. Reactivity with cell surface antigens was found infrequently (6 cultures), whereas reactivity with intracellular antigens was more common (27 cultures). A new cell surface antigen with properties of a glycolipid was defined with an IgM monoclonal antibody secreted by a tetraploid cell derived from a fusion of LICR-2 with lymphocytes from the axillary lymph node of a patient with melanoma. The hybrid cell line has been subcloned four times and secretes 5 micrograms IgM/ml. The antigen detected by this IgM antibody was found on 5 of 23 melanoma cell lines and 12 of 30 epithelial cancer cell lines. No reactions were found with 11 cultures derived from normal cells. Stable cell lines secreting human antibody that detected nuclei, nucleoli, cytoskeletal elements, Golgi complex, or other cytoplasmic components were also isolated in this study. One of these antibodies detected an intracellular antigen that is restricted to cells of neuroectodermal derivation, and a second antibody reacted primarily with cells of epithelial origin. Using these methods to isolate and analyze human monoclonal antibody, it should now be possible to define the repertoire of the humoral immune response to melanoma.

Anomalous exciton condensation in graphene bilayers.

In ordinary semiconductor bilayers, exciton condensates appear at total Landau-level filling factor nu{T}=1. We predict that similar states will occur in Bernal stacked graphene bilayers at many nonzero integer filling factors. For nu{T}=-3, 1 we find that the superfluid density of the exciton condensate vanishes and that a finite-temperature fluctuation-induced first order isotropic-smectic phase transition occurs when the layer densities are not balanced. These anomalous properties of bilayer graphene exciton condensates are due to the degeneracy of Landau levels with n=0 and n=1 orbital character.

Set-up and routine use of a database of 10,555 genotyped blood donors to facilitate the screening of compatible blood components for alloimmunized patients.

BACKGROUND AND OBJECTIVES: Large-scale genotyping of blood donors for red blood cell and platelet antigens has been predicted to replace phenotyping assays in the screening of compatible blood components for alloimmunized patients. Although several genotyping platforms have been described, novel procedures and processes are needed to perform genotyping efficiently and to maximize its benefits for blood banks. MATERIALS AND METHODS: Here we describe the processes and procedures developed to introduce large-scale genotyping in our routine operations. RESULTS: Preliminary cost-benefit analysis indicated that genotyping must target frequent blood donors (> 3 donations/year) to be efficiently used. A custom-designed computer application was developed to manage the whole project. It selects frequent donors among recent donations, prints coded labels to identify blood samples sent to the external genotyping laboratory, and stores genotyping results. It can search for donors compatible for any combination of the 22 genotyped antigens as well as consult the current inventory for the presence of the corresponding blood components. The phenotype of recovered components is confirmed by standard serology techniques prior to shipment to hospitals. CONCLUSION: Since October 2007, 10 555 blood donors have been genotyped. The database is used on a regular basis to find compatible blood components with a genotype-phenotype concordance of 99.6%.

Bioassay of prostate-specific antigen (PSA) using microcantilevers.

Diagnosis and monitoring of complex diseases such as cancer require quantitative detection of multiple proteins. Recent work has shown that when specific biomolecular binding occurs on one surface of a microcantilever beam, intermolecular nanomechanics bend the cantilever, which can be optically detected. Although this label-free technique readily lends itself to formation of microcantilever arrays, what has remained unclear is the technologically critical issue of whether it is sufficiently specific and sensitive to detect disease-related proteins at clinically relevant conditions and concentrations. As an example, we report here that microcantilevers of different geometries have been used to detect two forms of prostate-specific antigen (PSA) over a wide range of concentrations from 0.2 ng/ml to 60 microg/ml in a background of human serum albumin (HSA) and human plasminogen (HP) at 1 mg/ml, making this a clinically relevant diagnostic technique for prostate cancer. Because cantilever motion originates from the free-energy change induced by specific biomolecular binding, this technique may offer a common platform for high-throughput label-free analysis of protein-protein binding, DNA hybridization, and DNA-protein interactions, as well as drug discovery.

Detection and clinical importance of micrometastatic disease.

Metastatic relapse in patients with solid tumors is caused by systemic preoperative or perioperative dissemination of tumor cells. The presence of individual tumor cells in bone marrow and in peripheral blood can be detected by immunologic or molecular methods and is being regarded increasingly as a clinically relevant prognostic factor. Because the goal of adjuvant therapy is the eradication of occult micrometastatic tumor cells before metastatic disease becomes clinically evident, the early detection of micrometastases could identify the patients who are most (and least) likely to benefit from adjuvant therapy. In addition, more sensitive methods for detecting such cells should increase knowledge about the biologic mechanisms of metastasis and improve the diagnosis and treatment of micrometastatic disease. In contrast to solid metastatic tumors, micrometastatic tumor cells are appropriate targets for intravenously applied agents because macromolecules and immunocompetent effector cells should have access to the tumor cells. Because the majority of micrometastatic tumor cells may be nonproliferative (G0 phase), standard cytotoxic chemotherapies aimed at proliferating cells may be less effective, which might explain, in part, the failure of chemotherapy. Thus, adjuvant therapies that are aimed at dividing and quiescent cells, such as antibody-based therapies, are of considerable interest. From a literature search that used the databases MEDLINE(R), CANCERLIT(R), Biosis(R), Embase(R), and SciSearch(R), we discuss the current state of research on minimal residual cancer in patients with epithelial tumors and the diagnostic and clinical implications of these findings.

Association of p27Kip1 levels with recurrence and survival in patients with stage C prostate carcinoma.

BACKGROUND: There are few biologic determinants that are prognostic for patients with localized prostate cancer. We examined whether cellular levels of the cyclin-kinase inhibitor p27Kip1 (also known as p27) in prostate tumors could be used to predict progression of this disease. METHODS: Levels of p27 in tumor cell nuclei were assessed by immunohistochemical analysis of tissue sections from the primary tumors of 96 patients with stage C prostate carcinoma who had been treated by radical prostatectomy. Tumors were classified into one of the following three groups on the basis of the percentage of tumor cells showing nuclear p27 reactivity: low (0%-10%), moderate (11%-50%), and high (>50%). The Mantel-Haenszel test, Kaplan-Meier analysis, and the logrank test were used to calculate the probability that nuclear p27 levels were associated with tumor grade and substage, with a serum prostate-specific antigen (PSA) recurrence (defined as the finding of a detectable level [0.4 ng/mL or greater] of serum PSA following radical prostatectomy), with the recurrence of clinically evident disease, and with survival. All reported P values are two-sided. RESULTS: Luminal cells and basal cells of normal prostate glands showed high levels of nuclear p27 immunoreactivity in all tissue sections examined. Fifty-three tumors showed high p27 reactivity, 31 showed moderate reactivity, and 12 showed low or no detectable reactivity. Decreased levels of p27 were associated with tumor grade (P = .004). Tumor levels of p27 were not associated with preoperative prostate-specific antigen levels (P = .360) or with tumor substage (P = .320). However, decreased p27 reactivity was significantly associated with an increased probability of recurrence (P = .004) and decreased survival (P = .010). The median recurrence-free interval for patients with tumors showing high, moderate, or low p27 reactivity was 13.7 years, 8.4 years, and 4.7 years, respectively. Median survival times were more than 14 years, more than 13.5 years, and 8.1 years for patients in the high, moderate, and low p27 reactivity groups, respectively. CONCLUSION: Levels of nuclear p27 immunoreactivity in the primary tumor can be used to predict recurrence and survival among patients with localized prostate cancer.

Angiogenesis in bladder cancer: relationship between microvessel density and tumor prognosis.

BACKGROUND: Tumor stage, histologic grade, and regional lymph node status are currently used to obtain prognostic information about bladder cancers. However, additional prognostic indicators are needed to aid clinicians in selecting patients who would benefit most from specific therapies. A majority of studies assessing the prognostic value of measuring tumor angiogenesis (i.e., measurement of tumor microvessel densities) have found a positive association between increasing microvessel densities and worsening prognosis. PURPOSE: We explored the relationship between established prognostic indicators and the extent of tumor-associated angiogenesis in patients with invasive transitional cell carcinoma (TCC) of the bladder, and we determined whether tumor microvessel density measurement could be used independently to predict bladder tumor behavior. METHODS: Tumor tissue was obtained from 164 patients with invasive primary TCC of the bladder. The extent of tumor-associated angiogenesis in this tissue was evaluated by immunohistochemical methods using HPCA-1, a mouse monoclonal antibody directed against the endothelial cell antigen, CD34. The number of microvessels in a 200x microscopic high-power field (hpf) containing the area of greatest neovascularization within or immediately adjacent to each tumor was determined. The patient population was then divided into three equivalently sized groups, with tumors containing low (< or = 64), intermediate (65-99), or high (> or = 100) numbers of microvessels per hpf. Kaplan-Meier product limit estimates of overall survival and the complement of cumulative incidence curves for recurrence-free survival were plotted. When analyzing survival or recurrence, the logrank test was used to compare groups of patients with and without stratification according to tumor stage. Analysis of variance was used to test for an association between microvessel density and established prognostic variables. Reported P values are from two-sided tests. RESULTS: Microvessel density was significantly associated with disease-free (P < .0001) and overall (P = .0007) survival. The estimated probabilities of recurrence at 5 years were 19% (95% confidence interval [CI] = 8-29), 56% (95% CI = 43-69), and 68% (95% CI = 55-81) for patients with lowest, intermediate, and highest microvessel counts, respectively. Overall survival at 5 years was estimated to be 68% (95% CI = 56-81), 44% (95% CI = 30-57), and 34% (95% CI = 21-47) for the same three patient groups. Microvessel density was associated with disease progression in patients with organ-confined tumors, tumors extending through the bladder wall, and tumors that had spread to regional lymph nodes. Tumor angiogenesis was found to be an independent prognostic indicator when evaluated in the presence of histologic grade, pathologic stage, and regional lymph node status. CONCLUSION: Tumor angiogenesis, as determined by microvessel density measurement, is an independent prognostic indicator for patients with invasive TCC of the bladder.

Thrombospondin-1 expression in bladder cancer: association with p53 alterations, tumor angiogenesis, and tumor progression.

BACKGROUND: Thrombospondin-1 (TSP) is a 430-kd glycoprotein that is an important component of the extracellular matrix and is known to be a potent inhibitor of angiogenesis (i.e., formation of new blood vessels) both in vitro and in vivo. Several reports suggest that TSP possesses tumor suppressor function, possibly through its ability to inhibit tumor neovascularization. It has recently been shown that TSP expression is enhanced by the product of the p53 gene (also known as TP53). PURPOSE: We examined the role of TSP expression in tumor recurrence and overall survival in patients with invasive bladder cancer. We also examined the relationship between alterations in p53 protein expression, TSP expression, and tumor angiogenesis. METHODS: Tumors from 163 patients (with a median follow-up of 7.7 years) who underwent radical cystectomy for invasive transitional cell carcinoma of the bladder (63 patients with organ-confined disease and no lymph node involvement, 48 patients with extravesical extension of the disease and no lymph node involvement, and 52 patients with metastasis to regional lymph nodes) were examined for TSP expression by immunohistochemistry, utilizing monoclonal antibody MA-II, which recognizes an epitope in the amino-terminal region of TSP. For each tumor, microvessel density counts and p53 protein expression status (via immunohistochemistry) were also determined. TSP expression was graded as low, moderate, or high without knowledge of clinical outcome, p53 status, and microvessel density count; tumors with moderate and high TSP levels were considered as one group. Groups of patients were compared by Kaplan-Meier product limit estimates of overall survival, the complement of cumulative incidence curves for recurrence-free survival, and the stratified logrank test. Reported P values are two-sided. RESULTS: TSP expression was significantly associated with disease recurrence (P = .009) and overall survival (P = .023). Patients with low TSP expression exhibited increased recurrence rates and decreased overall survival. TSP expression was an independent predictor of disease recurrence (P = .002) and overall survival (P = .01) after stratifying for tumor stage, lymph node status, and histologic grade, but it was not independent of p53 status. TSP expression was significantly associated with p53 expression status (P = .001) and microvessel density counts (P = .001). Tumors with p53 alterations were significantly more likely to demonstrate low TSP expression, and tumors with low TSP expression were significantly more likely to demonstrate high microvessel density counts. Results of an analysis of variance were compatible with the hypothesis that p53 affects tumor angiogenesis by regulating the level of TSP expression. CONCLUSIONS AND IMPLICATIONS: These data support the concept that TSP may possess a tumor-inhibitory function. TSP may act, in part, through the regulation of tumor neovascularity. These results may also provide insight into one mechanism by which p53 exerts its tumor suppressor effects, i.e., through the control of tumor angiogenesis.

Effect of p21WAF1/CIP1 expression on tumor progression in bladder cancer.

BACKGROUND: Altered expression of p53 protein is an important predictor of progression in bladder cancer. The action of p53 on cell cycle regulation is mediated, in part, through expression of the cyclin-dependent kinase inhibitor p21WAF/CIP1 (p21). Loss of p21 expression may, therefore, contribute to tumor progression. We sought to determine the relationship between p21 expression in bladder cancer and disease progression. METHODS: Tumor specimens were obtained from 242 patients who underwent cystectomy for bladder cancer. Median follow-up was 8.5 years (range, 0.1-11.8 years). Nuclear p21 status was determined by immunohistochemistry and was then analyzed in relationship to the probability of tumor recurrence, overall survival, and tumor p53 status. Reported P values are two-sided. RESULTS: Nuclear p21 expression was detected in the tumors of 156 (64%) of the 242 patients. Patients with p21-positive tumors had a decreased probability of tumor recurrence (P<.00001) and an increased probability of overall survival (P<.00001) in comparison with patients with p21-negative tumors. In a multivariable analysis, p21 expression was an independent predictor of tumor recurrence (P = .0017) and of survival (P = .006) when assessed with tumor grade, tumor stage, lymph node status, and p53 status. p21 expression was associated with p53 status (P<.001); 56% of tumors with p53 alterations showed loss of p21 expression, whereas 79% of tumors expressing wild-type p53 were p21 positive. Patients with p53-altered/p21-negative tumors demonstrated a higher rate of recurrence and worse survival compared with those with p53-altered/p21-positive tumors (P<.0001). Patients with 53-altered/p21-positive tumors demonstrated a similar rate of recurrence and survival as those with p53-wild type tumors. CONCLUSION: Loss of p21 expression is a statistically significant and independent predictor of bladder cancer progression. Maintenance of p21 expression appears to abrogate the deleterious effects of p53 alterations on bladder cancer progression.

Genetic alterations of the p53 gene are a feature of malignant mesotheliomas.

A putative tumor suppressor gene, p53, has been shown to be altered in a variety of human tumor types. The primary mechanism of p53 inactivation is believed to be mutation of one allele followed by loss of the second allele. Malignant mesothelioma is a tumor that has been highly associated with exposure to asbestos fibers, which are known to cause chromosomal abnormalities in mesothelial cells. We have examined four mesothelioma cell lines for genetic abnormalities in p53. Cytogenetic analysis revealed that two of the four tumors had abnormalities (numerical and/or structural) of chromosome 17 (the locus of the p53 gene). Restriction fragment length polymorphism analysis using a chromosome 17p-specific probe (pYNZ22) revealed that two tumors had loss of heterozygosity in the region of 17p13. The relative level of p53 mRNA expression was examined by Northern analysis, with one tumor showing negligible expression of p53 mRNA. The complementary DNA of p53 was generated from the three tumors showing detectable mRNA expression, and the region between codons 70 and 319 was amplified by the polymerase chain reaction and sequenced. DNA single-base substitutions were detected in two of the tumor cell lines, each resulting in amino acid substitutions. One tumor had an arginine to histidine substitution at position 175, and one tumor had a glycine to aspartic acid substitution at position 245. The observed mutations took place in regions of high cross-species sequence homology, indicating that these regions may be functionally important. The correlation of chromosomal loss in 17p on the cytogenetic and molecular level along with p53 mRNA expression and DNA sequence data indicate that genetic alterations in p53 could be a feature of malignant mesotheliomas and may reveal an important role of asbestos fibers in tumor suppressor gene inactivation.

Tissue distribution and cellular location of the antigens recognized by human monoclonal antibodies 16.88 and 28A32.

Results from a previous study (M. V. Haspel et al., Cancer Res., 45: 3951-3961, 1985) indicated that it was possible to isolate a high proportion of human monoclonal antibodies reactive with cell surface, tumor-associated antigens when the hybridomas were obtained from fusions utilizing peripheral blood lymphocytes from patients immunized with autologous tumor cells. The assignment of membrane reactivity was made from immunoperoxidase studies which used air-dried, nonpermeabilized Cytospin preparations of colon tumor cells. Tumor specificity was assessed by immunohistological assays by using frozen sections of normal and malignant human tissues. We now describe a series of studies using two of these antibodies, 16.88 and 28A32, in which further information was obtained concerning the tumor specificity and cellular location of the target antigens reactive with these monoclonal antibodies. Data were acquired from a variety of experimental techniques which included quantitative and qualitative immunofluorescence on live and permeabilized cells, RBC-rosetting assays, immunoperoxidase studies on Cytospin and frozen tissue sections, and immunoblot procedures. These studies show that the 16.88 and 28A32 human monoclonal antibodies bind to antigens which (a) are located in the cell cytoplasm and are not expressed in detectable levels on the cell surface, and (b) are found in many normal and malignant cell types.

Immunohistochemical characterization of two monoclonal antibodies, P25.48 and P25.91, which define a new prostate-specific antigen.

We have generated two new mouse monoclonal antibodies against prostate cancer. P25.48 (IgG3) and P25.91 (IgG2a) were derived from a fusion using fresh prostate cancer cells as the immunogen. Initial screening was performed by indirect immunofluorescence on frozen tissue sections of prostate cancer specimens. The specificity analysis was performed by indirect immunoperoxidase on frozen sections of normal tissues and benign and malignant prostate tissues. P25.48 and P25.91 did not react with any benign prostatic tissues (0 of 17), but reacted with a subset of the malignant prostatic tissues. Five specimens of well-differentiated carcinoma were tested and did not react with P25.48 or with P25.91. Of 16 higher grade specimens, nine reacted with both P25.48 and P25.91, one reacted with P25.48 only, and one reacted with P25.91 only. In most positive cases, the reactivity was heterogenous. P25.48 and P25.91 showed a very restricted pattern of reactivity in nonprostatic tissues. Of 50 normal specimens, only one breast specimen showed some reactivity. None of the nine fetal tissues or of the 15 malignant tissues tested reacted with these monoclonal antibodies. The pattern of reactivity of P25.48 and P25.91 suggests that they recognize the same antigen. This antigen is selectively expressed by malignant prostatic epithelium. In addition, it appears to be distinct from all other previously described prostate cancer-associated antigens.

Sensitivity of immunocytochemical detection of breast cancer cells in human bone marrow.

We have previously shown that occult micrometastases can be detected in the bone marrow of breast cancer patients, at the time of initial treatment, using a panel of epithelial specific monoclonal antibodies indirectly labeled with fluorescein. These monoclonal antibodies permit us to detect cancer cells at at concentration of two/million normal bone marrow cells. Immunofluorescence carries the disadvantage that detailed morphological examination of detected cells cannot be accomplished. A modification of the alkaline phosphatase anti-alkaline phosphatase method has been used to detect cancer cells and to observe their morphology in human bone marrow. The sensitivity of this method has been examined using an established human metastatic breast cancer cell line (MCF-7) mixed with normal bone marrow cells at various dilutions from 400 cancer cells/10(6) marrow cells to 10 cancer cells/10(6) marrow cells. The number of immunocytochemically stained MCF-7 cells counted at each concentration was related to the concentration by a simple nonlinear statistical model. At a concentration of 10 cancer cells/10(6) bone marrow cells, the model shows that this method has the sensitivity to detect between four and six MCF-7 cells 95% of the time. Extrapolation, using this model, predicts that at the very low concentration of one cancer cell/10(6) marrow cells, there is a 95% chance of detecting the cancer cell. This assay may be a very sensitive method for detecting cancer cells in the bone marrow of breast cancer patients.

Immunofluorescent monoclonal antibody detection of breast cancer in bone marrow: sensitivity in a model system.

We have previously shown that occult micrometastases can be detected in the bone marrow of breast cancer patients using a panel of epithelial specific monoclonal antibodies in an indirect immunofluorescent assay. The sensitivity of this assay has been examined using cells from an established human breast cancer cell line (MCF-7) mixed with normal bone marrow at various dilutions from 400 cancer cells/10(6) marrow cells (400:10(6] to 10:10(6). MCF-7 cells were detected at the lowest concentration studied, namely 10:10(6). The number of fluorescent labeled MCF-7 cells counted at each concentration was related to the concentration by a simple nonlinear statistical model. At the concentration of 10:10(6), the model shows that this technique has the sensitivity to detect between two and four MCF-7 cells 95% of the time. Moreover, by extrapolation, the model predicts that even at the very low concentration of 2:10(6), there is a 95% chance of detecting one cancer cell. Therefore, this assay may be a very sensitive method for detecting cancer cells in the bone marrow in vivo.

Two molecular pathways to transitional cell carcinoma of the bladder.

Noninvasive transitional cell carcinomas of the bladder can have two distinct morphologies suggesting they contain different genetic alterations. Papillary transitional cell carcinomas (T(a) tumors) are often multifocal and only occasionally progress, whereas flat tumors (carcinomas in situ, CIS), frequently progress to invasive disease. We examined 216 bladder tumors of various stages and histopathologies for two genetic alterations previously described to be of importance in bladder tumorigenesis. Loss of heterozygosity of chromosome 9 was observed in 24 of 70 (34%) T(a) tumors but was present in only 3 of 24 (12%) CIS and dysplasia lesions (P = 0.04). In contrast, only 1 of 36 (3%) T(a) tumors contained a p53 gene mutation compared to 15 of 23 (65%) CIS and dysplasias (P < 0.001), a frequency comparable to that observed in muscle invasive tumors (25 of 49; 51%). The presence of p53 mutations in CIS and dysplasia could explain their propensities to progress since these mutations are known to destabilize the genome. Analysis of several tumor pairs involving a CIS and an invasive cancer provided evidence that the chromosome 9 alteration may in some cases be involved in the progression of CIS to more invasive tumors, in addition to its role in the initiation of T(a) tumors. However, the CIS and secondary tumor were found to contain different genetic alterations in some patients suggesting divergent progression pathways. Bladder carcinogenesis may therefore proceed through two distinct genetic alteration pathways responsible for generating superficial tumors with differing morphologies and pathologies.