Abstract. We report on the first stages of a clinical study designed to test elastic-scattering spectroscopy, mediated by fiberoptic probes, for three specific clinical applications in breast-tissue diagnosis: (1) a transdermal-needle (interstitial) measurement for instant diagnosis with minimal invasiveness similar to fine-needle aspiration but with sensitivity to a larger tissue volume, (2) a hand-held diagnostic probe for use in assessing tumor/resection margins during open surgery, and (3) use of the same probe for real-time assessment of the ''sentinel'' node during surgery to determine the presence or absence of tumor (metastatic). Preliminary results from in vivo measurements on 31 women are encouraging. Optical spectra were measured on 72 histology sites in breast tissue, and 54 histology sites in sentinel nodes. Two different artificial intelligence methods of spectral classification were studied. Artificial neural networks yielded sensitivities of 69% and 58%, and specificities of 85% and 93%, for breast tissue and sentinel nodes, respectively. Hierarchical cluster analysis yielded sensitivities of 67% and 91%, and specificities of 79% and 77%, for breast tissue and sentinel nodes, respectively. These values are expected to improve as the data sets continue to grow and more sophisticated data preprocessing is employed. The study will enroll up to 400 patients over the next two years. © 2000 Society of Photo-Optical Instrumentation Engineers. [S1083-3668(00)

Abstract. There are two isoforms of the vertebrate nonmuscle myosin heavy chain, MHC-A and MHC-B, that are encoded by two separate genes. We compared the enzymatic activities as well as the subcellular localizations of these isoforms in Xenopus cells. MHC-A and MHC-B were purified from cells by immunoprecipitation with isoform-specific peptide antibodies followed by elution with their cognate peptides. Using an in vitro motility assay, we found that the velocity of movement of actin filaments by MHC-A was 3.3-fold faster than that by MHC-B. Likewise, the Wma x of the actin-activated Mg 2÷-ATPase activity of MHC-A was 2.6-fold greater than that of MHC-B. Immunofluorescence microscopy demonstrated distinct localizations for MHC-A and MHC-B. In interphase cells, MHC-B was present in the cell cortex and diffusely arranged in the cytoplasm. In highly polarized, rapidly migrating interphase cells, the lamellipodium was dramatically enriched for MHC-B suggesting a possible involvement of MHC-B based contractions in leading edge extension and/or retraction. In contrast, MHC-A was absent from the cell periphery and was arranged in a fibrillar staining pattern in the cytoplasm. The two myosin heavy chain isoforms also had distinct localizations throughout mitosis. During prophase, the MHC-B redistributed to the nuclear membrane, and then resumed its interphase localization by metaphase. MHC-A, while diffuse within the cytoplasm at all stages of mitosis, also localized to the mitotic spindle in two different cultured cell lines as well as in Xenopus blastomeres. During telophase both isoforms colocalized to the contractile ring. The different subcellular localizations of MHC-A and MHC-B, together with the data demonstrating that these myosins have markedly different enzymatic activities, strongly suggests that they have different functions. MYosiN is a diverse superfamily of molecular motors that is currently represented by 12 distinct classes based on sequence homology (40). Myosins of class II (Myosin II) have both a structural and an enzymatic role in such diverse cellular processes as muscle contraction (15), cell division (11), cell locomotion (47, 7), and intracellular movements (11,25,30). All myosin II proteins share the same basic molecular structure of a dimer of heavy chains of ~200 kD noncovalently associated with two pairs of light chains of 17 kD and 20 kD. The myosin heavy chain dimers form two globular amino-terminal heads and a-helical coiled-coil rods. The heads contain an actin-activated ATPase activity while the rods are involved in filament formation. Both the heavy chain and light chain subunits of myosin exist as isoforms. In this paper, we report our studies on the function of isoforms of the heavy chain of nonmuscle myosin II.

CBFb-SMMHC is expressed from the inv(16) chromosome in M4Eo AML. Mice lacking CBF subunits or expressing the CBFb-SMMHC or AML1-ETO oncoproteins failed to develop de®nitive hematopoiesis. To investigate these e ects on hematopoiesis, we expressed CBFb-SMMHC from the metallothionein promoter, in both 32D cl3 myeloid cells and Ba/F3 B-lymphoid cells. Addition of zinc increased CBFb-SMMHC levels more than tenfold, with higher levels evident in Ba/F3 lines. Levels obtained in 32D cl3 cells were similar to those of endogenous CBFb. Indirect immuno¯uorescence revealed zinc-inducible speckled, nuclear staining in Ba/F3 cells and di use nuclear staining in 32D cl3 cells. CBFb-SMMHC reduced endogenous CBF DNA-binding ®vefold in both cell types, increased cell generation time 1.9-fold, on average, in 32D cl3 cells and 1.5-fold in Ba/ F3 cells and decreased tritiated thymidine incorporation into DNA correspondingly. CBFb-SMMHC increased the proportion of cells in G1 1.7-fold, on average, in 32D cl3 and Ba/F3 cells, and decreased the proportion of cells in S phase by a similar degree. CBFb-SMMHC induced a marked increase in hypophosphorylated Rb, but did not alter IL-3 Receptor a or b subunit levels. Neither apoptosis nor 32D di erentiation was induced by zinc in IL-3 in these lines. Induction of CBFb-SMMHC in 32D cl3 cells did not inhibit their di erentiation to neutrophils or their expression of myeloperoxidase mRNA in G-CSF, and did not produce an eosinophilic phenotype. Additional, proliferative genetic changes in M4eo AMLs might potentiate inhibition of di erentiation by CBFb-SMMHC by allowing its increased expression.

Abstract. Collagen lattices containing bovine retinal pericytes (RPs), vascular smooth muscle cells (VSMCs), pulmonary microvessel endothelial cells (PMECs), or aortic endothelial cells (AECs) were prepared and contraction was quantitated by measuring the resulting change in lattice area. VSMCs were the most efficient at lattice contraction followed by RPs and then PMECs. AECs did not contract the lattices. To document further that these observations represent contraction, cells were grown on inert silicone rubber sheets. Substratum wrinkling was indicative of tension development and quantitated as percent of cells contracted. RPs were more contractile than PMECs, and AECs were incapable of developing tension. VSMCs were less contractile than RPs, unlike the comparative contractility observed with the lattice system. Alteration of actin-containing filaments by cytochalasin B significantly reduced RP contraction of silicone rubber and inhibited their contraction of collagen lattices in a dose-dependent manner. Rhodamine-phalloidin staining of contracting RPs revealed microfilament bundle orientations that suggested their association in the force applied for contraction. RP, VSMC and PMEC contraction of collagen lattices was directly proportional to the concentration of fetal calf serum. Also, RP contraction was greater in calf serum than calf plasma-derived serum, an indication that RPs respond to substances that appear continuously and episodically in blood. These in vitro findings support the theory that pericytes in vivo are contractile but that endothelial cells may also contribute to microvascular tonus.