Immunoblot analysis of c-Met expression in human colorectal cancer: Overexpression is associated with advanced stage cancer

c-Met, the receptor of hepatocyte growth factor is known to be responsible for the motility and mitogenesis of epithelial cells including cancer cells. To investigate the significance of c-Met expression in human colorectal cancer (CRC), total cellular protein, extracted from 130 CRCs were examined by Western blot analysis. The signal was quantitated by ChemiImager™ 4000 Low Light Imaging System. c-Met expression was analyzed as the ratio of tumor to matched normal tissue (T/N) and expressed as fold-increase. The cellular localization of c-Met was assessed by immunohistochemistry. The T/N fold increase of c-Met varied from 0.2 to 10.7 with a mean of 3.41 ± 0.23 (mean ± SE). 69% primary CRC showed overexpression (T/N >2.0) of c-Met. Significantly higher c-Met levels were found in CRC with blood vessel invasion (P = 0.04), and in advanced stage (P = 0.04). No relationship was noted between c-Met expression and age, tumor size, location, differentiation. C-Met immunoreactivity was observed in the membrane and cytoplasm of cancer cells. Positive staining of endothelial cells of blood vessels within normal submucosa and tumor was also evident. C-Met protein is expressed at levels significantly higher than adjacent mucosa in most primary adenocarcinomas of the colon. Our results support an important role for c-Met in human CRC progression and metastasis.     

Trying to stop smoking: Effects of perceived addiction,attributions for failure,and expectancy of success

This paper reports the results of a postal questionnaire completed by 2343 smokers who had contacted a television company for help with stopping smoking. Of these, 1848 (78.9%) completed a follow-up questionnaire 1 year later. This indicated that 797 had tried to stop, 709 had tried to cut down, and 164 had become abstinent. Analyses show that the intention to try to stop smoking was dependent not only on the perceived health benefit, but also on the subjects' confidence that they would succeed if they tried to stop. As predicted by Weiner's [(1979). J. Educ. Psychol.71: 3–25] model of achievement motivation, those who attributed other smokers' failures at quitting to stable factors had lower expectancies of success, as had those who saw themselves as more addicted. When the follow-up data are considered, reported attempts at quitting were strongly related to previously declared intentions, and reported abstinence was related to previous confidence (expectancy of success) and perceived addiction. There is no support for hypotheses concerning self-other differences in attribution, or defensive attribution, in subjects' attributions for their own failures at cessation. Implications for antismoking interventions are discussed.This research was facilitated to various extents by grants from the British Council, the Department of Health and Social Security, the Medical Research Council, and the Social Science Research Council, London. When the data were collected, all authors were at the Addiction Research Unit, Institute of Psychiatry, University of London.     

The Heritability of Depression Symptoms in Elderly Danish Twins: Occasion-Specific Versus General Effects

Depression symptomatology was assessed up to four times at 2-year intervals on a sample of 2100 Danish twins initially aged 70 years and older. Data were analyzed using the biometric growth model approach proposed by Neale and McArdle (2000). Results show that occasion-specific depression is moderately and equally heritable in men and women (occasion-specific estimates of heritability ranged from 22% to 37%). Estimates of phenotypic variance, genetic variance, and heritability did not vary systematically across waves. In the best-fitting growth model, depression symptomatology was accounted for by two factors: (1) a level (i.e., average) effect that was highly heritable (estimate of 69% in women and 64% in men) and reflected overall vulnerability, and (2) a residual effect that was nonheritable and reflected occasion-specific circumstances that could either exacerbate or moderate inherited vulnerability. Attempts to identify specific genetic contributions to depression might profitably focus on average levels across multiple assessments, while attempts to identify specific environmental effects might profitably focus on deviations about this average.     

QUANTITATIVE EVOKED POTENTIAL CORRELATES OF THE PROBABILITY OF EVENTS

A late positive-going component (P₃) of the average evoked potential recorded from human scalp was shown to be quantitatively related to a priori stimulus probability both when the S was told the identity of the stimulus before it was presented and when the S was not told, and was instructed to guess. In the guessing situation, the amplitude of P₃ was much larger and was influenced not only by the a priori probability of events determined by the experimenter but also by the interaction of these probabilities with the S's guessing behavior. The amplitude of the late positive component was inversely related to the proportion of trials in which a particular event was associated with a particular guess, i.e., the proportion of hits and misses. It was larger the more unexpected the outcome of the guess. This relationship held for different methods of manipulating the probability of two events.     

Mapping of a restriction fragment length polymorphism associated with defective DR beta 4 chain expression to the HLA-DRB1 gene

The HLA-DR beta 4 chain, encoded by the DRB4 gene, carries two DRw53 determinants normally expressed by DR4, DR7, and DR9 individuals. However, some DR7 individuals (DR7, Dw11) fail to express the DR beta 4 chain. At the genomic level, a HindIII restriction fragment length polymorphism can be detected in these individuals with a DR beta cDNA probe. The association of this altered HindIII fragment with defective beta 4 chain expression suggested the possibility that the polymorphic fragment was derived from the DRB4 gene and might, therefore, be related to the defect in expression. However, detailed Southern blot analysis has now mapped the polymorphic fragment to the 3' end of the DRB1 gene, approximately 100 kb away from the defective DRB4 gene. Although the alteration in the DRB1 gene might involve sequences important in regulating the expression of the DRB4 gene, it is more likely that the association results from strong positive linkage disequilibrium between these DR beta chain genes.     

Regulation of in vitro cytotoxic T lymphocyte generation. II. Demonstration of noncytotoxic alloantigen-specific suppressor T lymphocytes

Both allospecific suppressor T lymphocytes (TsS) and nonspecific suppressor T lymphocytes (TsN) are activated in alloantigen-stimulated mixed leukocyte cultures (MLC). TsS and TsN can suppress cytotoxic T lymphocyte (CTL) induction upon transfer to fresh (second) MLC stimulated by the same alloantigens as in the first MLC (TsS or TsN) or by third-party alloantigens (TsN only). Evidence that TsS and TsN functions are performed by different T cell sets has been restricted to radioresistance of the former but not the latter. Separation of TsS from CTL has proven even more difficult. Methods are reported here which have allowed in vitro induction and functional separation of TsS from CTL and TsN in a totally allogeneic system. TsS are resistant to combined exposure to pyrilamine, a histamine1 antagonist and local anesthetic, during suppressor cell induction, and to X or gamma irradiation thereafter, while CTL precursors (CTL-P) and TsN are more sensitive to such treatments. This allowed us to use these treatments to generate TsS that are not contaminated with functional CTL, CTL-P or TsN. These data show that TsS regulate CTL induction by interacting with responding cell populations, rather than by cytotoxic depletion of stimulator cells.     

A novel method for making "tissue" microarrays from small numbers of suspension cells.

Tissue microarrays (TMAs) are a highly efficient method for large-scale protein expression studies. To date most TMAs have been constructed using paraffin-embedded specimens. The authors developed a method that allows construction of TMAs from small numbers of cells in suspension. Spun pellets of 1x10 to 1x10 cells are directly processed and embedded in paraffin in an Eppendorf tube. Cylindrical cores of 0.6 mm are taken from these tubes and embedded in a recipient paraffin block to create a TMA. This relatively simple but versatile method enables very small numbers of cells in suspension to be analyzed using the TMA technology and allows for the study of hematolymphoid and related disorders of the blood and bone marrow for which solid tissue samples cannot be readily obtained. With the increasing trend toward obtaining small samples for screening and diagnostic purposes, this method provides a means to manipulate small volume samples for high-throughput immunohistochemical analysis. This method is also amenable for use for cultured cells.     

Results of a study to correlate serum prostate specific antigen and reproductive hormone levels in patients with localized prostate cancer.

This cross-sectional study was undertaken to determine whether serum hormones (free testosterone, androstenedione, luteinizing hormone, or prolactin) have any influence on serum prostate specific antigen (PSA) levels in patients with stage A-C prostate cancer. Blood samples were collected prior to any treatment in 36 patients; in 19 (group 1), three blood samples were collected 10 minutes apart between 9:00 AM and 9:30 AM for each patient and pooled together to avoid diurnal and episodic variation in serum testosterone values. In the remaining patients, only one sample could be collected (group 2). Free testosterone, androstenedione, luteinizing hormone, prolactin, and PSA levels were determined with appropriate radioimmunoassay techniques. Statistical analyses were performed separately for groups 1 and 2, and then with pooled data. None of the hormones in any of the analyses showed any association to serum PSA values except for prolactin for the pooled data and for group 2. This statistical significance for prolactin disappeared on multivariate analysis. There were 21 African-American men and 15 whites in the study; no racial differences in hormonal levels were found except for lower luteinizing hormone levels in African Americans in group 2 and pooled data. No differences were found between group 1 and group 2 in the mean serum prolactin and luteinizing hormone values. Serum free testosterone, androstenedione, and luteinizing hormone appeared to have no influence on serum PSA values in nonmetastatic cancer patients. Serum prolactin values were inversely associated with PSA values in univariate analysis for the pooled data; this disappeared in multivariate analysis. Unlike other studies that found higher serum testosterone levels in African-American college students than whites, no such differences were seen in this age group. Luteinizing hormone was lower in African-American men than in whites in the pooled study population. Further studies are needed to clarify our findings.