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Biomedical subjects

E M Grossman

Publications and source records attributed to E M Grossman.

7 recordsLinked to original sources
PubMed2000

The role of cyclooxygenase enzymes in the growth of human gall bladder cancer cells.

Information suggests that the cyclooxygenase (COX) metabolites, the prostanoids, play a role in gall bladder physiology and disease. Non-steroidal anti-inflammatory drugs which inhibit COX enzymes have been shown in vivo and in vitro to alter the growth patterns of intestinal epithelial cells, and specific COX-2 inhibitors have been shown to decrease mitogenesis in intestinal epithelial cells. The present study was intended to evaluate the effect of specific COX inhibitors on the growth patterns of gall bladder cancer cells. Employing a human gall bladder cancer cell line, mitogenesis, apoptosis and prostaglandin E(2) (PGE(2)) formation were evaluated in response to serum and hepatocyte growth factor and transforming growth factor alpha stimulation in the presence and absence of specific COX-1 and -2 inhibitors. The effect of the mitogens on COX enzyme expression was also evaluated. Serum and the growth factors increased COX enzyme expression and mitogenesis, and decreased apoptosis as evaluated by the percentage of cells that were floating in culture media rather than attached. There was more DNA degradation in floating than in attached cells. The specific COX-2 inhibitor, but not the COX-1 inhibitor, decreased mitogenesis and increased gall bladder cell apoptosis as evaluated by the number of floating versus attached cells and the number of floating cells in the terminal phase of apoptosis or dead. The inhibition of mitogenesis and the increased apoptosis produced by the COX-2 inhibitor was associated with decreased PGE(2) production. The inhibition of replication of gall bladder cancer cells and the increase in apoptosis produced by the selective COX-2 inhibitor suggests that the COX enzymes and the prostanoids may play a role in the development of gall bladder cancer and that the COX-2 inhibitors may have a therapeutic role in the prevention of gall bladder neoplasms.

Apoptosis↗
PubMed2000

Role of cytoplasmic and secretory phospholipase A2 in intestinal epithelial cell prostaglandin E2 formation.

BACKGROUND: Prostanoid production is dependent on the enzymatic activity of phospholipase A2 enzymes to produce the precursor, arachidonic acid. Two principle phospholipase A2 enzymes play a major role in arachidonic acid production, 85kDa cytoplasmic phospholipase A2 (cPLA2) and 14kDa secretory phospholipase A2 (sPLA2). The purpose of this study was to determine the PLA2 enzyme involved in prostanoid formation in intestinal epithelial cells. METHODS: Employing a human and murine intestinal epithelial cell line, cells were exposed to the stimulants lipopolysaccharide (LPS), interleukin 1beta (IL-1) and calcium ionophore (Ca Ion) in the presence and absence of cPLA2 and sPLA2 inhibitors. The expression of both PLA2 enzymes and prostaglandin E2 (PGE2) formation were determined. RESULTS: Western blotting demonstrated that the cPLA2 enzyme was constitutively expressed in the human cell lines and not evidently increased by exposure to any of the stimulants. In murine cells the cPLA2 enzyme was also constitutively expressed and not induced by the stimulants evaluated. The sPLA2 enzyme was constitutively expressed in both cell lines and appeared to be induced by LPS and IL-1 in human enterocytes but not by Ca Ion. In murine enterocytes sPLA2 was induced by all three stimuli. PGE2 production by the human cell line was increased by LPS, IL-1 and Ca Ion. IL-1 and Ca Ion stimulated PGE2 formation was inhibited by the cPLA2 enzyme inhibitors while LPS stimulated PGE2 production was not inhibited by the cPLA2 inhibitor; but was inhibited by the sPLA2 enzyme inhibitor. Murine epithelial cells increased PGE2 formation in response to IL-1 and Ca Ion, but not LPS and the increased PGE2 was significantly decreased by cPLA2 enzyme inhibitors. CONCLUSIONS: The metabolic pathway of PGE2 formation is variable and the PLA2 enzyme involved in producing PGE2 is dependent on the stimulus and the cell line. In human intestinal epithelial cells, LPS production of PGE2 proceeds through a pathway associated with sPLA2 generated arachidonic acid while IL-1 stimulated PGE2 is produced by arachidonic acid generated by cPLA2. The physiologic significance of the various metabolic pathways of PGE2 formation is unknown.

Cell Line↗
PubMed1984

Some methodological issues in the conduct of caffeine research.

The caffeine literature of the past 10 years shows the frequent recurrence of several weaknesses--the use of weak or erroneous hypotheses in experimental design, design flaws (e.g. the use of excessively high doses) that prevent the derivation of any meaningful implication for humans, the violation of ordinary rules of logic in extrapolating experimental results to human situations (e.g. the application of findings in naive animals to caffeine-tolerant human subjects) and the biased selection of literature citations to support a hypothesis and ignore opposing evidence. Workers who review the literature dispassionately, who use dosages relevant to human caffeine consumption when they wish to extrapolate from animal studies to man, who distinguish carefully between acute and chronic effects and who include proper controls in feeding studies to prevent confusion of the effects of dietary deprivation with the pharmacological effects should succeed in advancing our understanding of caffeine's effects in the human body.

Animals↗