Suicidal plant poisoning with Colchicum autumnale.

Colchicum autumnale is commonly known as autumn crocus, and as 'gowri gedde' in the southern region of Karnataka State in South India. It contains an alkaloid called colchicine, which blocks the cell division by inhibiting mitosis. We present a sporadic case of suicidal plant poisoning wherein a 24-year-old man consumed 'gowri gedde' to end his life. Initially he presented with severe vomiting, diarrhoea and epigastric pain. He died on the third day of ingestion due to multiorgan failure. Chemical analysis of blood and viscera obtained postmortem confirmed the presence of colchicine. Colchicine poisoning is potentially life threatening because of its high toxicity and unavailability of specific antidotal treatment. It classically presents with gastroenterocolitis, and may result in multiorgan failure in fatal cases.

Actin polymerization in response to different chemoattractants is reduced in granulocytes from chronic myeloid leukemia patients.

Chronic myeloid leukemia (CML), a hematopoietic stem cell disorder, is characterized by the presence of Philadelphia chromosome (Ph1). Earlier studies have shown that various functions, such as chemotaxis, fluid phase pinocytosis, phagocytosis, and degranulation in response to chemotactic peptide formyl-methionyl-leucyl-phenylalanine (fMLP), were defective in polymorphonuclear leukocytes (PMNL) from CML patients. These functions depend on actin microfilaments (MF). Further studies showed that fMLP-induced actin polymerization was lower in CML PMNL. To see if this defect is specific to stimulation by fMLP alone or is a global phenomenon involving other chemoattractant receptors, chemotaxis and actin polymerization were studied in response to fMLP, an analog of fMLP, formyl-methionine-1 aminocyclooctane 1 carboxylic acid-phenyalanine-O-methionine (FACC8), platelet-activating factor (PAF), and leukotriene B4 (LTB4). These compounds bind to different chemoattractant receptors. Chemotaxis and actin polymerization in response to all four chemoattractants were significantly lower in CML PMNL compared with PMNL from normal subjects and were differentially affected for the different chemoattractants. These results suggest a global phenomenon involving all four chemoattractant-stimulated pathways. This lower amount of F-actin may be responsible for the defective chemotaxis seen in these cells.

Granulocytes from chronic myeloid leukemia (CML) patients show differential response to different chemoattractants.

Binding of chemoattractant to polymorphonuclear leukocytes (PMNL) triggers a series of events like polymerization of actin and tubulin, orientation of cells, chemotaxis, increase in fluid pinocytosis and phagocytosis, and stimulation of microbicidal pathways which includes lysosomal degranulation and generation of reactive oxygen species. Earlier studies from our laboratory have shown that stimulation of chemotaxis, fluid pinocytosis, and actin polymerization of CML PMNL in response to a synthetic chemotactic peptide formyl-methionyl-leucyl-phenylalanine (fMLP) is significantly lower than that in normal PMNL. It is not known whether this lower response of CML PMNL to fMLP is a global phenomenon involving different chemoattractant receptors or is restricted to the fMLP pathway. We have evaluated chemoattractant induced degranulation process in normal and CML PMNL to fMLP, platelet activating factor (PAF), leukotriene B4 (LTB4), and an analogue of fMLP viz formyl-methionine-1 aminocyclooctane 1 carboxylic acid-phenylalanine-O-methionine (FACC8) using release of lysozyme as a parameter. We find that after stimulation with fMLP and FACC8, the mean percent release of lysozyme was significantly lower in CML PMNL as compared to that in normal cells (P < 0.001). There was no significant difference between the two after stimulation with PAF and LTB4. The results indicate that the fMLP pathway is suppressed in CML granulocytes whereas PAF and LTB4 pathways appear unaltered in these cells. We therefore also studied the kinetics of peptide-receptor interaction with a labelled hexapeptide fNLPNTL which binds to the fMLP receptor. Our results show that the number of fMLP receptors/cell is significantly lower in CML PMNL (P < 0.05) than in normal PMNL, while their affinity constants and dissociation constants were comparable.

Fluid pinocytosis and esterase-oxidase in chronic myeloid leukemic granulocytes are differentially stimulated by chemotactic peptide.

Binding of a chemotactic peptide, n-formyl-methionyl-leucyl-phenylalanine (FMLP) to polymorphonuclear leukocytes (PMNL) leads to a series of biochemical and functional events. We have studied stimulation of fluid phase pinocytosis (FP), esterase and oxidase by FMLP in CML PMNL, by flow cytometry. Stimulation of FP in CML PMNL was lower than that in normal PMNL but, stimulation of esterase and oxidase was comparable to that in normal PMNL. Thus, early response to FMLP which is dependent on the integrity of actin network seems to be defective in CML PMNL.

Flow cytometric studies on actin polymerization in PMN cells from chronic myeloid leukemia (CML) patients.

Studies in our laboratory have shown that polymorphonuclear leucocytes (PMNL) from chronic myeloid leukemia (CML) patients are defective in chemotaxis towards a synthetic peptide, n-formyl-methionyl-leucyl-phenylalanine (FMLP), during the active phases of the disease and in remission. Actin plays a major role in cellular movements and binding of chemo-attractant to cells induces polymerization of G-actin to F-actin. We have, therefore, compared polymerization of actin in FMLP stimulated PMNL from CML patients with those from normal subjects by fluorescence microscopy and flow cytometry, using F-actin specific probe, NBD-phallacidin. Our results show that binding of FMLP to normal PMNL induces rapid conversion of G-actin to F-actin followed by depolymerization to some extent. In CML PMNL, such a biphasic response is not seen. Conversion of G-actin to F-actin is slower and F-actin content is significantly lower than that in normal PMNL. Moreover, organization of F-actin is different in CML PMNL as compared to that in normal PMNL.

PMN cells from chronic myeloid leukemia (CML) patients show defective chemotaxis in remission.

The chemotactic index (C.I.) of granulocytes from chronic myeloid leukemia (CML) patients at diagnosis and in subsequent remission was measured using different concentrations of the synthetic chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine (FMLP), by time lapse cinematography and compared with that of normal granulocytes. The C.I. of CML polymorphonuclear leucocytes (PMNL) at diagnosis and in remission was significantly lower than the C.I. of PMNL from normal subjects (p less than 0.001 and 0.05 greater than p greater than 0.02, respectively). PMNL from CML patients at diagnosis showed increased speed after stimulation with FMLP. In most of the CML patients, the highest values of C.I., speed and the number of motile cells were obtained at FMLP concentrations of 10-100-fold higher than those required for normal PMNL. These results suggest an alteration in the interaction between FMLP and its receptors and that events occurring after FMLP binding are also altered. It was earlier shown that PMNL from CML patients in the active stages of the disease show defective chemotaxis. Present studies show persistence of such defective cells in the peripheral blood of CML patients in remission. These results also suggest that defects in PMNL from CML patients in remission. These results also suggest that defects in PMNL from CML patients may be constitutional.