In vivo measurements of frequency-dependent attenuation in tumors of the liver

Ultrasonic frequency-dependent attenuation (FDA) coefficients of the liver obtained from selected regions of interest within the liver were determined in 106 individuals, 40 cases presumed normal based on medical histories and 66 with malignant tumors (hepatocellular carcinoma [HCC] or metastatic liver tumor) or benign tumors (hepatic hemangioma, hepatic adenoma, or focal nodular hyperplasia of the liver). All liver tumors were confirmed histopathologically by ultrasonically guided fine-needle biopsy and/or operation. Mean attenuation of normal liver was 0.53 +/- 0.03 dB/cm/MHz, 0.29 +/- 0.05 dB/cm/MHz in hepatic hemangioma, 0.43 +/- 0.05 dB/cm/MHz in HCC, and 0.41 +/- 0.12 dB/cm/MHz in metastatic liver tumor. Hepatic adenoma and focal nodular hyperplasia of the liver produced higher values, averaging 0.66 +/- 0.09 dB/cm/MHz. This difference between malignant and benign tumors was statistically significant. There was some correlation between the FDA for the hepatic tumor and the histopathology that merits further investigation.

Inverse correlation between expression of inducible nitric oxide synthase activity and production of metastasis in K-1735 murine melanoma cells

The purpose of these studies was to determine whether the induction of NO synthase activity in murine K-1735 melanoma cells correlated with their metastatic potential. Nonmetastatic, metastatic, and somatic cell hybrids (produced by fusion of nonmetastatic and metastatic cells) were injected i.v. into syngeneic C3H/HeN mice. Metastatic cells survived to produce experimental lung metastases, whereas nonmetastatic cells did not. The various clones and somatic cell hybrids were incubated in vitro with combinations of tumor necrosis factor, interleukin 1, gamma-interferon, and lipopolysaccharide. Nonmetastatic cells exhibited high levels of inducible NO synthase activity and NO, whereas metastatic cells did not. Both the cytotoxic effects of the cytokines and NO production were inhibited by the addition of NG-monomethyl-L-arginine, a specific inhibitor of NO synthase. These data demonstrate an inverse correlation between production of endogenous NO and the ability of K-1735 cells to survive in syngeneic mice to produce lung metastases.

Leukocyte-induced angiogenesis and subcutaneous growth of B16 melanoma

We investigated the mechanism(s) by which systemic administration of doxorubicin (DXR) produced growth retardation of B16 melanomas in the subcutis of syngeneic mice. DXR or saline was injected intravenously (i.v.) into C57BL/6 mice, and B16-BL6 cells were implanted subcutaneously (s.c.) on day 3, 7, or 21 after DXR treatment. In the DXR-pretreated mice, the tumors grew at a slower rate than in control (saline-treated) mice. The experiments were repeated with a B16 variant resistant to DXR with similar results. Tumor growth retardation correlated with extent of myelosuppression monitored by counting bone marrow cells, circulating leukocytes and peritoneal macrophages. In DXR-pretreated mice reconstituted with 1 x 10(7) viable syngeneic spleen cells, the s.c. tumors grew at a rate similar to that in control mice. DXR treatment and spleen cell reconstitution experiments were repeated in BALB/c athymic nude mice. The results were very similar. The growth of s.c. tumors was directly correlated with the degree of peritumoral vascularity. These data indicate that in addition to its well-documented direct antitumor effects, DXR may produce retardation of tumor growth by producing myelosuppression and, hence, inhibition of host cell-induced tumor angiogenesis.

Nuclear dot antigens may specify transcriptional domains in the nucleus

A bank of 892 human autoimmune serum samples was screened by indirect immunofluorescence on human tissue culture HT-29 cells. Seven serum samples that stain 4 to 10 bright dots in cell lines of several different mammals, including humans, monkeys, rats, and pigs, were identified. Immunofluorescence experiments indicate that these antigens, called nuclear dot (ND) antigens, are distinct from splicing complexes, kinetochores, and other known nuclear structures. An ND antigen recognized by these sera was cloned by immunoscreening a human lambda gt11 expression library. Analysis of seven cDNA clones for the ND antigen indicates that several mRNAs exist, perhaps derived through alternative splicing mechanisms. One major form of the message has an open reading frame of 1,440 bp capable of encoding a 53,000-M(r) protein. Treatment of cells with detergent, salt, or RNase A fails to remove the ND antigen from the nucleus. However, incubation with DNase I obliterates ND staining, indicating that the ND protein directly or indirectly associates with nuclear DNA. Fusion of the ND protein to a LexA DNA binding domain activates transcription in Saccharomyces cerevisiae. A 75-amino-acid domain that activates transcription in both yeast and primate cells has been identified. We suggest that ND antigens may participate in the activation of transcription of specific regions of the genome.

Protein tyrosine kinase inhibitors decrease induction of nitric oxide synthase activity in lipopolysaccharide-responsive and lipopolysaccharide-nonresponsive murine macrophages

We investigated tumoricidal activation and induction of nitric oxide synthase (NOS) activity in macrophages from LPS-responsive (C3H/HeN) and -unresponsive mice (C3H/HeJ). Macrophages were incubated in vitro with a synthetic lipopeptide or with LPS and IFN-gamma. LPS and IFN-gamma activated C3H/HeN but not C3H/HeJ macrophages to lyse B16 melanoma cells. In contrast, lipopeptide and IFN-gamma activated macrophages from both strains of mice. Genistein, a specific inhibitor of protein tyrosine kinase, significantly blocked tumoricidal activation of macrophages from both strains of mice. Genistein did not affect tumor cell binding but significantly inhibited the production of nitric oxide. Genistein, herbimycin A, and tyrphostin inhibited the induction of NOS activity in macrophages from both strains of mice. These data suggest that protein tyrosine kinase activity is involved in the signal transduction pathway of LPS and other synthetic bacterial-related immunomodulators at a point preceding triggering of macrophage tumoricidal activation and expression of inducible NOS activity.

Protein tyrosine kinase inhibitors decrease induction of nitric oxide synthase activity in lipopolysaccharide-responsive and lipopolysaccharide-nonresponsive murine macrophages

We investigated tumoricidal activation and induction of nitric oxide synthase (NOS) activity in macrophages from LPS-responsive (C3H/HeN) and -unresponsive mice (C3H/HeJ). Macrophages were incubated in vitro with a synthetic lipopeptide or with LPS and IFN-gamma. LPS and IFN-gamma activated C3H/HeN but not C3H/HeJ macrophages to lyse B16 melanoma cells. In contrast, lipopeptide and IFN-gamma activated macrophages from both strains of mice. Genistein, a specific inhibitor of protein tyrosine kinase, significantly blocked tumoricidal activation of macrophages from both strains of mice. Genistein did not affect tumor cell binding but significantly inhibited the production of nitric oxide. Genistein, herbimycin A, and tyrphostin inhibited the induction of NOS activity in macrophages from both strains of mice. These data suggest that protein tyrosine kinase activity is involved in the signal transduction pathway of LPS and other synthetic bacterial-related immunomodulators at a point preceding triggering of macrophage tumoricidal activation and expression of inducible NOS activity.