A large number of aggressive cancer cell lines display elevated levels of activated Rac1, a small GTPase widely implicated in cytoskeleton reorganization, cell motility, and metastatic dissemination. A commonly accepted methodological approach for detecting Rac1 activation in cancer cells involves the use of a conformation-sensitive antibody that detects the active (GTP-bound) Rac1 without interacting with the GDP-bound inactive form. This antibody has been extensively used in fixed cell immunofluorescence and immunohistochemistry. Taking advantage of prostate and pancreatic cancer cell models known to have high basal Rac1-GTP levels, here we have established that this antibody does not recognize Rac1 but rather detects the intermediate filament protein vimentin. Indeed, Rac1-null PC3 prostate cancer cells or cancer models with low levels of Rac1 activation still show a high signal with the anti-Rac1-GTP antibody, which is lost upon silencing of vimentin expression. Moreover, this antibody was unable to detect activated Rac1 in membrane ruffles induced by epidermal growth factor stimulation. These results have profound implications for the study of this key GTPase in cancer, particularly because a large number of cancer cell lines with characteristic mesenchymal features show simultaneous up-regulation of vimentin and high basal Rac1-GTP levels when measured biochemically. This misleading correlation can lead to assumptions about the validity of this antibody and inaccurate conclusions that may affect the development of appropriate therapeutic approaches for targeting the Rac1 pathway.

OBJECTIVE: There is increasing interest in ultrasound-diagnosed non-alcoholic fatty liver disease (NAFLD) in the ambulatory care setting. The aim of this study was to determine the clinical and metabolic features of ultrasound-diagnosed NAFLD.
METHODS: Fifty ultrasound-diagnosed NAFLD patients who had not consumed alcohol for at least the previous 3 months were matched with 100 controls by age and gender distribution. Clinical, biochemical, and nutritional variables were compared between the ultrasound-diagnosed NAFLD patients and the controls. Conditional logistic regression analyses were used to identify independent factors associated with ultrasound-diagnosed NAFLD.
RESULTS: The ultrasound-diagnosed NAFLD patients had higher values on the anthropometric measurements than those of the controls. Aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT), uric acid, and gamma-glutamyl transpeptidase levels were higher in the ultrasound-diagnosed NAFLD patients than those in the controls (p<0.001). The ASAT/ALAT ratio of the ultrasound-diagnosed NAFLD patients was lower than that of the controls (p<0.001). Total cholesterol, triglycerides, high-density lipoprotein (HDL)-cholesterol, non-HDL-cholesterol, atherogenic index, fasting glucose, systolic blood pressure (BP), diastolic BP, and pulse pressure were higher in the ultrasound-diagnosed NAFLD patients than in the control subjects, while lipoprotein(a) was lower. There were no significant differences in low-density lipoprotein (LDL)-cholesterol levels or nutritional intake between patients and controls. Abnormal ASAT or ALAT, hypertriglyceridemia, lower HDL-cholesterol levels, silent myocardial ischemic pattern on electrocardiogram (ECG), impaired fasting glucose, and obesity were common among the ultrasound-diagnosed NAFLD patients. The only independent factor associated with ultrasound-diagnosed NAFLD was obesity (p<0.001).
CONCLUSIONS: Our data suggest that NAFLD diagnosed by ultrasound is associated with hypertriglyceridemia, impaired fasting glucose, silent myocardial ischemic pattern of ECG, obesity, and abnormal liver tests in adults. Among these factors, obesity was the only independent factor associated with ultrasound-diagnosed NAFLD.

G-protein coupled receptors (GPCRs) represent the largest membrane proteins family in animal genomes. Being the receptors for most hormones and neurotransmitters, these proteins play a central role in intercellular communication. GPCRs can be classified into several groups based on the sequence similarity of their common structural feature: the heptahelical domain. The metabotropic receptors for the main neurotransmitters glutamate and gamma-aminobutyric acid (GABA) belong to the class III of GPCRs, together with others receptors for Ca2+, for sweet and amino acid taste compounds and for some pheromones, as well as for odorants in fish. Besides their transmembrane heptahelical domain responsible for G-protein activation, most of class III receptors possess a large extracellular domain responsible for ligand recognition. The recent resolution of the structure of this binding domain of one of these receptors, the mGlu1 receptor, together with the recent demonstration that these receptors are dimers, revealed an original mechanism of activation for these GPCRs. Such data open new possibilities to develop drugs aimed at modulating these receptors, and raised a number of interesting questions on the activation mechanism of other GPCRs.

The concept of Molecular Science of the Living Organism was described, where the living state is explained as the purposive flows of the quantum mechanically controlled chemical reaction systems which support the homeostasis of the living organism. In the 21st century, the post genomic sequence era, the concept may be a self-evident truth. Molecular Science of the Living Organism was presented in the case of G-proteins: i.e., the atomically controlled mechanism of 1. the carcinogenesis which originates from the point mutation of ras p21, 2. the activation of a receptor protein at the cell membrane, especially in the case of bacteriorhodopsin, 3. the activation of an inactive G-protein by the activated receptor protein.

BACKGROUND: T-cell lymphoid blastic phase (BP) transformation is rare in chronic myelogenous leukemia (CML). 2-amino-9-beta-D-arabinosyl-6-methoxy-9H-guanine (GW506U78), a prodrug of arabinosylguanine (ara-G), is effective in T-cell leukemias.
METHODS: The authors present a case of a 48-year-old male with Philadelphia chromosome (Ph) positive CML and T-cell lymphoid BP after 17 months in the chronic phase.
RESULTS: Plasma pharmacokinetic studies after an infusion of GW506U78 at a dose of 40 mg/kg showed GW506U78 concentrations of 60 microM, and a peak ara-G concentration of 260 microM in the plasma. Cellular ara-G triphosphate (ara-GTP) concentration in the peripheral blood T-lymphoblasts was 80 microM at the end of GW506U78 infusion and reached a maximum of 150 microM. The patient achieved a complete response that lasted 13 months. Severe neurotoxicity related to GW506U78 was observed.
CONCLUSIONS: GW506U78 showed antileukemic activity against Ph positive T-cell BP CML. Neurotoxicity was dose-limiting in this patient. Treatment with GW506U78 and modulation of ara-GTP concentrations are therapeutic strategies that require further exploration in T-cell malignancies. Investigation of other dosing schedules may limit neurotoxicity.

The binding of T7 lysozyme to T7 RNAP increases the apparent Km for NTP during initiation (formation of the first phosphodiester bond). It also increases the dissociation constant and dissociation rate of product dinucleotide from the polymerase. Higher NTP concentrations are required for maximal rates of productive initiation from T7 class II versus class III promoters, though individual promoters display distinct responses to changes in NTP concentrations. The greater degree of repression of class II versus class III promoters by T7 lysozyme, which appears to be important for the switch to class III gene expression during the phage life cycle, might therefore be a consequence of: (1) T7 lysozyme generally reducing the affinity of the polymerase for NTPs and increasing the rate of release of transcripts, and (2), intrinsically higher NTP concentration requirements for productive initiation from class II promoters. T7 lysozyme is also found to inhibit the addition of untemplated bases to the transcript which can occur when the elongation complex reaches the end of a template, and its effects are qualitatively similar to those reported for mutations in the extreme C terminus of T7 RNAP. Together with the locations of polymerase mutations which cause resistance or hypersensitivity to T7 lysozyme, these observations suggest that the structural mechanism of lysozyme action might include conformational changes in the C-terminal loop (aa. approximately 820-883) of T7 RNAP.

Cells from a patient with childhood acute lymphoblastic leukemia contain an apparent DNA polymerase activity that was not found in any other cells except thymus cells. The enzyme has the properties of terminal transferase, an enzyme known to be found in thymocytes. The cells also contain the three major DNA polymerases found in growing cells. The results suggest that these tumor cells arose from a block in the differentiation of thymocytes. Terminal transferase may be a marker for the origin of leukemic cells.

Guanosine 5\'-O-(3-thio)triphosphate (GTP gamma S) was found to be a substrate of pig heart succinyl-CoA synthetase with Km and kcat values of 3 microM and 0.23 s-1, respectively. The corresponding values with GTP as substrate were 48 microM and 65 s-1. 35S-thiophosphorylated enzyme was prepared by incubation of pig heart succinyl-CoA synthetase with [35S]GTP gamma S. A comparison was made of thiophosphoryl group release by substrates from this alpha beta (one active site) enzyme with that of the alpha 2 beta 2 (two active sites) Escherichia coli enzyme (Wolodko, W. T., Brownie, E. R., O\'Connor, M. D., and Bridger, W. A. (1983) J. Biol. Chem. 258, 14116-14119; Nishimura, J. S., and Mitchell, T. (1984) J. Biol. Chem. 259, 9642-9645). It was found, as in the case of the E. coli enzyme, that thiophosphoryl group release by GDP and by succinate plus CoA was stimulated by succinyl-CoA and GTP, respectively. The same result was observed at 1, 0.1, and 0.01 mg/ml, lending assurance that these phenomena were not exhibited by an aggregated form of the pig heart enzyme. While an alternating-sites catalytic cooperativity model is not ruled out for the E. coli enzyme, it is proposed that the NTP- and succinyl-CoA-stimulated release of thiophosphoryl groups from either enzyme involves a \"same-site\" mechanism, to be distinguished from an \"other-site\" mechanism.

A patient with refractory acute myeloid leukemia was treated with tiazofurin, an agent that causes inhibition of tumor cell proliferation by depressing GTP concentrations in the malignant cells. The initial dose of 1100 mg/m2 was ineffective clinically and biochemically. Dose escalations to 1650, 2200, and finally 3300 mg/m2 resulted in a marked decrease in the absolute number of blasts without causing bone marrow hypoplasia or marked neutropenia. The decrease in the peripheral blast cell count was observed subsequent to a decline in GTP concentrations in the leukemic cells to less than 30% of the pretreatment value. Consecutive bone marrow examinations showed a remarkable shift from myeloblasts to more mature myeloid elements, suggesting an in vivo differentiative action of tiazofurin. Although a total dose of 23,650 mg/m2 was administered over a 13-day period, only very mild side effects were noted. The absence of complications reported by others in Phase I trials with tiazofurin may be related to our slow administration of the drug by pump over a 1-h period in this trial. Tiazofurin appears to be a promising agent in the treatment of leukemia because of its selective action on leukemic cells and the availability of a rapid in vitro method capable of predicting sensitivity of leukemic cells to the agent and monitoring its activity during treatment by measuring thiazole-4-carboxamide adenine dinucleotide and GTP concentrations. These observations are being tested in a larger group of leukemic patients.

A case of erythropoietic protoporphyria (EPP) with severe acute abdominal pain and jaundice was reported. Erythrocyte protoporphyrin (PP) levels were constantly high, and liver histology showed a slight fibrosis with inflammatory infiltration. During the investigation period of 18 months, erythrocyte PP levels closely paralleled those of serum gamma-GTP.