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1.
Sci Total Environ ; 490: 970-8, 2014 Aug 15.
Article in English | MEDLINE | ID: mdl-24914526

ABSTRACT

Drugs of abuse are increasingly consumed worldwide. Such consumption could be back-calculated based on wastewater content. The West Indies, with its coca production and its thriving illicit drug market, is both a hub of world cocaine trafficking and a place where its consumption is prevalent particularly in the form of crack. The present study will firstly investigate Caribbean consumption by a daily 5 to 7 day sampling campaign of composite wastewater samples from the four wastewater treatment plants of the Martinique capital, including working and non-working periods. The local consumption of cocaine is ten to thirty times higher than OECD standards because of the prevalence of crack. The excretion coefficient for crack consumption and the impact of temperature on drug stability need further investigation. However, the low diversity of illicit drugs consumed and the crack prevalence suggest practices driven by the transiting of drugs for international trafficking.


Subject(s)
Environmental Monitoring , Pharmaceutical Preparations/analysis , Substance Abuse Detection , Wastewater/chemistry , Drug Trafficking , Illicit Drugs/analysis , Martinique/epidemiology , Sewage/chemistry , Sewage/statistics & numerical data , Substance-Related Disorders/epidemiology , Waste Disposal, Fluid/statistics & numerical data , Wastewater/statistics & numerical data , Water Pollutants, Chemical/analysis
2.
Circulation ; 102(19): 2322-4, 2000 Nov 07.
Article in English | MEDLINE | ID: mdl-11067782

ABSTRACT

BACKGROUND: In photoangioplasty, light activation of a photosensitive drug offers the potential for treatment of long segments of vascular disease. This is a brief description of a study designed to evaluate the safety and tolerability of a new photosensitizer, Antrin (motexafin lutetium), in the endovascular treatment of atherosclerosis. METHODS AND RESULTS: An open-label, single-dose, escalating drug- and light-dose study was performed in patients with atherosclerotic peripheral arterial insufficiency. Clinical evaluation, serial quantitative angiography, and intravascular ultrasonography were performed. Therapy was well tolerated, and only minor side effects were observed. Treatment produced no deleterious vascular effects. Although this study was not designed to examine clinical efficacy, several secondary end points suggested a favorable therapeutic effect. CONCLUSIONS: This phase I study demonstrates that photoangioplasty with motexafin lutetium is well tolerated and safe. Preliminary efficacy data suggest a future role for the treatment of flow-limiting atherosclerosis.


Subject(s)
Peripheral Vascular Diseases/drug therapy , Photochemotherapy/methods , Photosensitizing Agents/therapeutic use , Humans , Ultrasonography
3.
Can J Commun Ment Health ; 19(1): 21-35, 2000.
Article in French | MEDLINE | ID: mdl-12152177

ABSTRACT

This paper reviews articles pertaining to mental health prevention and promotion programs that have used mass media as a component of their program. The programs are analyzed according to four roles that media can play in health promotion programs: promotion, education, complementarity, and support. The relationship between the function assigned to the media and the effects of the programs in changing knowledge, attitudes, or behaviour is explored. When mass media are used alone, they seem to be powerful in recruiting people into groups or social services and in enhancing knowledge and changing attitudes. But when it comes to changing behaviour, mass media by themselves have limited impact. This type of change is more likely to occur when media are combined with face-to-face intervention. Finally, some issues involved in improving the use of mass media in mental health are discussed.


Subject(s)
Mass Media/statistics & numerical data , Mental Health Services/organization & administration , Preventive Health Services/organization & administration , Humans
4.
Oncogene ; 15(11): 1303-7, 1997 Sep.
Article in English | MEDLINE | ID: mdl-9315098

ABSTRACT

Formation of active cdk (cyclin dependent kinase)/ cyclin kinases involves phosphorylation of a conserved threonine residue in the T loop of the cdk catalytic-subunit by CAK (Cdk Activating Kinase). CAK was first purified biochemically from higher eukaryotes and identified as a trimeric complex containing a cdk7 catalytic subunit, cyclin H and MAT1 (Ménage à trois), a member of the RING finger family. The same trimeric complex is also part of basal transcription factor TFIIH. In budding yeast, the closest homologs of cdk7 and cyclin H, KIN28 and CCL1, respectively, also associate with TFIIH. However, the KIN28/CCL1 complex does not display CAK activity and a distinct protein kinase able to phosphorylate monomeric CDC28 and GST-cdk2 was recently identified, challenging the identification of cdk7 as the physiological CAK in higher eukaryotes. Here we demonstrate that immunodepletion of cdk7 suppresses CAK activity from cycling Xenopus egg extracts, and arrest them before M-phase. We also show that specific translation of mRNAs encoding Xenopus cdk7 and its associated subunits restores CAK activity in cdk7-immunodepleted Xenopus egg extracts. Hence, the cdk7 complex is necessary and sufficient for activation of cdk-cyclin complexes in cycling Xenopus egg extracts.


Subject(s)
CDC2-CDC28 Kinases , Cell Cycle/physiology , Cyclins/metabolism , Protein Serine-Threonine Kinases/metabolism , Xenopus/embryology , Animals , Chromatin/genetics , Chromatin/metabolism , Cyclin A/genetics , Cyclin A/metabolism , Cyclin H , Cyclin-Dependent Kinase 2 , Cyclin-Dependent Kinases/genetics , Cyclin-Dependent Kinases/metabolism , Embryo, Nonmammalian/metabolism , Histones/metabolism , Male , Mitosis , Phosphorylation , Precipitin Tests , Protein Biosynthesis , Protein Serine-Threonine Kinases/genetics , Protein Serine-Threonine Kinases/immunology , Rabbits , Recombinant Proteins/genetics , Recombinant Proteins/immunology , Recombinant Proteins/metabolism , Spermatozoa/chemistry , Xenopus Proteins , Cyclin-Dependent Kinase-Activating Kinase
5.
Am J Respir Crit Care Med ; 155(6): 1835-40, 1997 Jun.
Article in English | MEDLINE | ID: mdl-9196083

ABSTRACT

Inhaled allergens, acting through IgE-dependent mechanisms, are important triggers of asthma symptoms and inducers of airway hyperresponsiveness and airway inflammation. The effect of anti-IgE recombinant humanized monoclonal antibody-E25 (rhuMAb-E25) on the provocation concentration of allergen causing a 15% fall in FEV1 (allergen PC15) during the allergen-induced early asthmatic response (EAR) was assessed in a multicenter, randomized, double-blind, parallel group study. Ten of 11 allergic asthmatic subjects randomized to receive intravenous rhuMAb-E25, 2 mg/kg on study day 0 and 1 mg/kg on Days 7, 14, 28, 42, 56, and 70 completed the study; nine received intravenous placebo. The allergen PC15 was measured on Days -1, 27, 55, and 77 and methacholine PC20 on Days -2, 42, and 76. rhuMAb-25 was well tolerated and only one patient (active group) was withdrawn because of a generalized urticarial rash after the first dose. Compared with baseline values (Day -1), the median allergen PC15 on Days 27, 55, and 77 were increased by 2.3, 2.2, and 2.7 doubling doses (delta log PC15/0.3) respectively with rhuMAb-E25 and -0.3, +0.1, and -0.8 doubling doses with placebo (p < or = 0.002). Methacholine PC20 improved slightly after rhuMAb-E25, this change becoming statistically significant on Day 76 (p < 0.05); no change was observed in the placebo group. Mean serum-free IgE fell by 89% after rhuMAb-E25 while there was no significant change after placebo. The inhibitory effects of rhuMAb-E25 on allergen-induced EAR suggest that it may be an effective, novel antiallergic treatment for asthma.


Subject(s)
Allergens/immunology , Antibodies, Monoclonal/therapeutic use , Asthma/immunology , Asthma/therapy , Hypersensitivity, Immediate/immunology , Hypersensitivity, Immediate/therapy , Immunoglobulin E/immunology , Adult , Antibodies, Monoclonal/adverse effects , Antibodies, Monoclonal/analysis , Double-Blind Method , Female , Humans , Immunoglobulin E/analysis , Male , Methacholine Chloride , Middle Aged
6.
Am J Respir Crit Care Med ; 153(6 Pt 1): 1914-7, 1996 Jun.
Article in English | MEDLINE | ID: mdl-8665055

ABSTRACT

The goal of this study was to evaluate the safety and efficacy of recombinant human DNase (rhDNase) in hospitalized patients with cystic fibrosis (CF) experiencing acute pulmonary exacerbations. Eighty patients with documented CF were enrolled at 11 CF centers when admitted for antibiotic therapy. Patients were at least 5 yr old with a forced vital capacity (FVC) > or = 35% of predicted and an oxygen saturation > or = 90% on a fraction of inspired oxygen (FIO2) < 0.5. Patients were randomized to receive rhDNase 2.5 mg in 2.5 ml excipient twice a day (n = 43) or 2.5 ml excipient alone twice daily (n = 37) along with conventional treatment for exacerbations. Administration of rhDNase was not associated with acute adverse events or deaths, and no patients experienced allergic or anaphylactic reactions. Although forced expiratory volume in one second (FEV1) and FVC improved in both treatment groups during the double-blind period, there were no statistically significant differences in the mean change from baseline in FEV1 or FVC between the two groups. rhDNase therapy is safe and well tolerated in CF patients with acute exacerbations requiring hospitalization, but the study did not demonstrate a statistically significant therapeutic effect of rhDNase when added to a regimen of antibiotics and chest physical therapy.


Subject(s)
Cystic Fibrosis/drug therapy , Deoxyribonuclease I/therapeutic use , Expectorants/therapeutic use , Acute Disease , Adult , Aerosols , Cystic Fibrosis/physiopathology , Deoxyribonuclease I/administration & dosage , Double-Blind Method , Drug Therapy, Combination , Expectorants/administration & dosage , Female , Hospitalization , Humans , Male , Oxygen/blood , Recombinant Proteins/administration & dosage , Recombinant Proteins/therapeutic use , Respiratory Function Tests , Treatment Outcome
7.
EMBO J ; 14(20): 5027-36, 1995 Oct 16.
Article in English | MEDLINE | ID: mdl-7588631

ABSTRACT

The kinase responsible for Thr161-Thr160 phosphorylation and activation of cdc2/cdk2 (CAK:cdk-activating kinase) has been shown previously to comprise at least two subunits, cdk7 and cyclin H. An additional protein co-purified with CAK in starfish oocytes, but its sequencing did not reveal any similarity with any known protein. In the present work, a cDNA encoding this protein is cloned and sequenced in both starfish and Xenopus oocytes. It is shown to encode a new member of the RING finger family of proteins with a characteristic C3HC4 motif located in the N-terminal domain. We demonstrate that the RING finger protein (MAT1: 'menage à trois') is a new subunit of CAK in both vertebrate and invertebrates. However, CAK may also exist in oocytes as heterodimeric complexes between cyclin H and cdk7 only. Stable heterotrimeric CAK complexes were generated in reticulocyte lysates programmed with mRNAs encoding Xenopus cdk7, cyclin H and MAT1. In contrast, no heterodimeric cyclin H-cdk7 complex could be immunoprecipitated from reticulocyte lysates programmed with cdk7 and cyclin H mRNAs only. Stabilization of CAK complexes by MAT1 does not involve phosphorylation of Thr176, as the Thr176-->Ala mutant of Xenopus cdk7 could engage as efficiently as wild-type cdk7 in ternary complexes. Even though starfish MAT1 is almost identical to Xenopus MAT1 in the RING finger domain, the starfish subunit could not replace the Xenopus subunit and stabilize cyclin H-cdk7 in reticulocyte lysate, suggesting that the MAT1 subunit does not (or not only) interact with cyclin H-cdk7 through the RING finger domain.


Subject(s)
Cyclin-Dependent Kinases , Cyclins/metabolism , Multigene Family , Protein Serine-Threonine Kinases/genetics , Protein Serine-Threonine Kinases/metabolism , Receptor Protein-Tyrosine Kinases/metabolism , Amino Acid Sequence , Animals , Base Sequence , Cloning, Molecular , Cyclin H , Discoidin Domain Receptor 1 , Molecular Sequence Data , Polymerase Chain Reaction , Precipitin Tests , Protein Binding , Protein Conformation , Recombinant Proteins/biosynthesis , Reticulocytes/enzymology , Sequence Homology, Amino Acid , Starfish/genetics , Xenopus/genetics , Cyclin-Dependent Kinase-Activating Kinase
8.
EMBO J ; 13(21): 5155-64, 1994 Nov 01.
Article in English | MEDLINE | ID: mdl-7957080

ABSTRACT

p40MO15, a cdc2-related protein, is the catalytic subunit of the kinase (CAK, cdk-activating kinase) responsible for Thr161/Thr160 phosphorylation and activation of cdk1/cdk2. We have found that strong overexpression of p40MO15 only moderately increases CAK activity in Xenopus oocytes, indicating that a regulatory CAK subunit (possibly a cyclin-like protein) limits the ability to generate CAK activity in p40MO15 overexpressing oocytes. This 36 kDa subunit was microsequenced after extensive purification of CAK activity. Production of Xenopus CAK activity was strongly reduced in enucleated oocytes overexpressing p40MO15 and p40MO15 shown to contain a nuclear localization signal required for nuclear translocation and generation of CAK activity. p40MO15 was found to be phosphorylated on Ser170 and Thr176 by proteolytic degradation, radiosequencing of tryptic peptides and mutagenesis. Thr176 phosphorylation is required and Ser170 phosphorylation is dispensable for p40MO15 to generate CAK activity upon association with the 36 kDa regulatory subunit. Finally, Thr176 and Ser170 phosphorylations are not intramolecular autophosphorylation reactions. Taken together, the above results identify protein-protein interactions, nuclear translocation and phosphorylation (by an unidentified kinase) as features of p40MO15 that are required for the generation of active CAK.


Subject(s)
Cell Compartmentation , Cell Nucleus/metabolism , Cyclin-Dependent Kinases , Protein Serine-Threonine Kinases/metabolism , Threonine/metabolism , Amino Acid Sequence , Animals , Base Sequence , Biological Transport , Enzyme Activation , Molecular Sequence Data , Oocytes , Phosphorylation , Phosphoserine/isolation & purification , Phosphothreonine/isolation & purification , Protein Binding , Protein Conformation , Protein Serine-Threonine Kinases/genetics , Recombinant Proteins/metabolism , Sequence Analysis , Sequence Homology, Amino Acid , Structure-Activity Relationship , Xenopus , Cyclin-Dependent Kinase-Activating Kinase
9.
Oncogene ; 9(11): 3127-38, 1994 Nov.
Article in English | MEDLINE | ID: mdl-7936635

ABSTRACT

Transitions of the cell cycle are controlled by cyclin-dependent protein kinases (cdks) whose phosphorylation on the Thr residue included in the conserved sequence YTHEVV dramatically increases the activity. A kinase responsible for this specific phosphorylation, called CAK for cdk-activating kinase, has been recently purified from starfish and Xenopus oocytes and shown to contain the MO15 gene product as a catalytic subunit. In the present paper, we have cloned the human homolog of Xenopus p40MO15 by probing a HeLa cell cDNA library with degenerate oligonucleotides deduced from Xenopus and starfish MO15 sequences. Human and Xenopus MO15 displayed a strong homology showing 86% identity with regard to amino acid sequences. Northern blot analysis of RNA extracts from a series of human tissues as well as from cultured rodent fibroblasts revealed a unique 1.4 kb MO15 mRNA. No variation in the amount of MO15 transcript or protein was found along the entire course of the fibroblast cell cycle. Fluorescence in situ hybridization on human lymphocyte metaphases showed two distinct chromosomal locations of human MO15 gene at 5q12-q13 and 2q22-q24. By using gene tagging and mammalian cell transfection, we demonstrate that the KRKR motif located at the carboxy terminal end of MO15 is required for nuclear targeting of the protein. Mutation of KRKR to NGER retains MO15 in the cytoplasmic compartment, whilst the wild-type protein is detected exclusively in the nucleus. Interestingly, we demonstrate that the nuclear targeting of MO15 is necessary to confer the protein its CAK activity. In contrast to the wild-type, the NLS-mutated MO15 expressed in Xenopus oocytes is unable to generate CAK as long as the nuclear envelope is not broken. The nuclear localization of both the MO15 gene product and CAK activity may imply that cdks activation primarily occurs in the cell nucleus.


Subject(s)
Cyclin-Dependent Kinases , Protein Serine-Threonine Kinases/genetics , Amino Acid Sequence , Animals , Base Sequence , Catalysis , Cell Nucleus/metabolism , Cells, Cultured , Chromosome Mapping , Chromosomes, Human, Pair 2 , Chromosomes, Human, Pair 5 , Cloning, Molecular , DNA, Complementary , HeLa Cells , Humans , Molecular Sequence Data , Protein Serine-Threonine Kinases/chemistry , Protein Serine-Threonine Kinases/metabolism , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Sequence Homology, Amino Acid , Xenopus , Cyclin-Dependent Kinase-Activating Kinase
10.
Mol Cell Biol ; 13(12): 7380-92, 1993 Dec.
Article in English | MEDLINE | ID: mdl-8246958

ABSTRACT

In multidrug-resistant (MDR) derivatives of the mouse lymphoid tumor P388, the emergence of MDR is associated with overexpression and transcriptional activation of the mdr3 gene, either in the absence of (P388/VCR-10) or concomitant with (P388/ADM-2) gene amplification. In both instances, Northern (RNA) blotting analyses have suggested the presence of altered mdr3 transcripts in these cells, possibly originating from novel transcription initiation sites. The mechanisms underlying mdr3 overexpression in these cells have been investigated. In P388/VCR-10 cells, Southern blotting analyses together with genomic DNA cloning and nucleotide sequencing have demonstrated the presence of an intact mouse mammary tumor virus (MMTV) within the boundaries of intron 1 of mdr3. cDNA cloning and nucleotide sequencing indicated that this integration event results in the synthesis and overexpression of a hybrid MMTV-mdr3 mRNA which initiates within the U3 region of the 5' long terminal repeat (LTR) of the provirus. Consequently, this mRNA lacks the normal exon 1 of mdr3 but contains (i) MMTV LTR-derived sequences at its 5' end, (ii) a novel mdr3 exon, mapping within the boundaries of intron 1 downstream of the MMTV integration site and generated by alternative splicing, and (iii) an otherwise intact 3' portion of mdr3 starting at exon 2. A similar type of analysis of P388/ADM-2 cells revealed that mdr3 overexpression in these cells is associated with the integration of an intracisternal A particle (IAP) within an L1Md repetitive element, immediately upstream of mdr3. The IAP insertion results in the overexpression of hybrid IAP-mdr3 mRNA transcripts that initiate within the 3' LTR of the IAP and which contain IAP LTR-derived sequences at the 5' end spliced 14 nucleotides upstream of the normal exon 1 of mdr3. Taken together, these results indicate that independent retroviral insertions were the initial mutagenic event responsible for mdr3 overexpression and survival during drug selection of these cell lines. Amplification of the rearranged and activated mdr3 gene copy occurred during further selection for high-level drug resistance in P388/ADM-2 cells.


Subject(s)
Drug Resistance/genetics , Gene Expression Regulation, Neoplastic , Leukemia P388/genetics , Mammary Tumor Virus, Mouse/genetics , Animals , Base Sequence , Chromosome Mapping , Cloning, Molecular , DNA, Neoplasm/genetics , Enhancer Elements, Genetic , Gene Rearrangement , Lysogeny/genetics , Mice , Molecular Sequence Data , Promoter Regions, Genetic , Proviruses/genetics , RNA, Messenger/genetics , RNA, Neoplasm/genetics , Transcriptional Activation , Tumor Cells, Cultured/drug effects
11.
Br J Clin Pharmacol ; 36(3): 263-5, 1993 Sep.
Article in English | MEDLINE | ID: mdl-9114914

ABSTRACT

Pravastatin is an HMG CoA reductase inhibitor used in the treatment of hypercholesterolaemia. The steady state pharmacokinetics of pravastatin (20 mg) and digoxin (0.2 mg) were evaluated in 18 healthy male subjects following the administration of each drug alone or in combination for 9 days. Serum and urine were collected for up to 48 h after the ninth dose in this open, randomized 3-way crossover study. Digoxin concentrations were measured by radioimmunoassay, and pravastatin and its metabolites. SQ 31,906 and SQ 31,945 were measured by GC-MS. Digoxin and pravastatin pharmacokinetics were unchanged following combined administration. Combination therapy with pravastatin and digoxin is unlikely to expose patients to additional risk compared with pravastatin alone.


Subject(s)
Anticholesteremic Agents/pharmacokinetics , Cardiotonic Agents/pharmacokinetics , Digoxin/pharmacokinetics , Pravastatin/pharmacokinetics , Adult , Anticholesteremic Agents/blood , Cardiotonic Agents/blood , Cross-Over Studies , Digoxin/blood , Drug Interactions , Humans , Male , Molecular Structure , Pravastatin/blood
12.
Atherosclerosis ; 101(1): 97-110, 1993 Jun.
Article in English | MEDLINE | ID: mdl-8216507

ABSTRACT

Epidemiologic evidence linking elevated cholesterol concentrations and coronary heart disease (CHD) through the eighth decade of life provides a rationale for lowering cholesterol concentrations to reduce morbidity and mortality from CHD. Pravastatin, a well tolerated HMG CoA reductase inhibitor with a convenient once-daily dosing regimen, has been shown to effectively lower total and low density lipoprotein (LDL) cholesterol. Individual data from more than 1800 hypercholesterolemic patients enrolled in six double-blind, randomized, multicenter studies were pooled and then analyzed to compare the safety and efficacy of pravastatin in the elderly (i.e., patients at least 65 years old) and the non-elderly. In short-term studies (8-16 weeks), response was dose-related and similar in elderly and non-elderly subjects. Pravastatin 20 or 40 mg daily lowered total cholesterol 19-25%, LDL-cholesterol 25-33%, and triglycerides 14-23%; high density lipoprotein (HDL) cholesterol increased 5-10%. During long-term studies, improvements were sustained for more than 24 months in both the non-elderly and elderly. The incidences of adverse drug events and laboratory abnormalities were similar in the elderly and non-elderly patients in all groups (active treatment control with resin, pravastatin alone, or combination therapy). In short-term studies, treatment was discontinued because of adverse events in < 1% of all patients treated with pravastatin (all doses) or placebo. The frequency and profile of adverse events were similar among patients treated with pravastatin or placebo. In long-term studies, treatment was discontinued in 0.4% of patients in the pravastatin group and in 0.3% of the patients in the bile-acid-binding resin group. If drug therapy is warranted, pravastatin appears to be safe and effective for long-term use in elderly patients with hypercholesterolemia.


Subject(s)
Pravastatin/therapeutic use , Adult , Age Factors , Aged , Cholesterol/blood , Female , Humans , Hypercholesterolemia/blood , Hypercholesterolemia/drug therapy , Male , Middle Aged , Pravastatin/administration & dosage , Pravastatin/adverse effects , Triglycerides/blood
13.
Int J Clin Pharmacol Ther Toxicol ; 31(6): 291-4, 1993 Jun.
Article in English | MEDLINE | ID: mdl-8335426

ABSTRACT

The pharmacokinetics and pharmacodynamics of pravastatin 20 mg administered twice daily when taken with or one hour before meals were evaluated in 24 hypercholesterolemic men in an 8-week, open-label, randomized, two-way crossover study. The bioavailability of pravastatin was reduced significantly (p < or = 0.001) when it was taken with meals (AUC dropped 31% and Cmax dropped 49%), and mean Tmax increased 50% (p < or = 0.01). The mean elimination t1/2 was unaffected by taking pravastatin with food. However, reductions in mean total cholesterol and low density lipoprotein cholesterol were identical whether pravastatin was given with or before meals. In both treatment groups, total cholesterol and low-density lipoprotein cholesterol were significantly reduced from baseline (p < 0.001). These results indicate that although the bioavailability of pravastatin is reduced when taken with meals, the lipid-lowering efficacy of pravastatin is not altered. It can be concluded that pravastatin can be ingested without regard to meal time.


Subject(s)
Food , Hypercholesterolemia/blood , Lipids/blood , Pravastatin/pharmacology , Pravastatin/pharmacokinetics , Cholesterol/blood , Cholesterol, LDL/blood , Humans , Male , Middle Aged , Time Factors
14.
J Cell Biol ; 118(5): 1109-20, 1992 Sep.
Article in English | MEDLINE | ID: mdl-1387401

ABSTRACT

We have produced human cyclin A in Escherichia coli and investigated how it generates H1 kistone kinase activity when added to cyclin-free extracts prepared from parthenogenetically activated Xenopus eggs. Cyclin A was found to form a major complex with cdc2, and to bind cdk2/Eg1 only poorly. No lag phase was detected between the time when cyclin A was added and the time when H1 histone kinase activity was produced in frog extracts, even in the presence of 2 mM vanadate, which blocks cdc25 activity. Essentially identical results were obtained using extracts prepared from starfish oocytes. We conclude that formation of an active cyclin A-cdc2 kinase during early development escapes an inhibitory mechanism that delays formation of an active cyclin B-cdc2 kinase. This inhibitory mechanism involves phosphorylation of cdc2 on tyrosine 15. Okadaic acid (OA) activated cyclin B-cdc2 kinase and strongly reduced tyrosine phosphorylation of cyclin B-associated cdc2, even in the presence of vanadate. 6-dimethylamino-purine, a reported inhibitor of serine-threonine kinases, suppressed OA-dependent activation of cyclin B-cdc2 complexes. This indicates that the kinase(s) which phosphorylate(s) cdc2 on inhibitory sites can be inactivated by a phosphorylation event, itself antagonized by an OA-sensitive, most likely type 2A phosphatase. We also found that cyclin B- or cyclin A-cdc2 kinases can induce or accelerate conversion of the cyclin B-cdc2 complex from an inactive into an active kinase. Cyclin B-associated cdc2 does not undergo detectable phosphorylation on tyrosine in egg extracts containing active cyclin A-cdc2 kinase, even in the presence of vanadate. We propose that the active cyclin A-cdc2 kinase generated without a lag phase from neo-synthesized cyclin A and cdc2 may cause a rapid switch in the equilibrium of cyclin B-cdc2 complexes to the tyrosine-dephosphorylated and active form of cdc2 during early development, owing to strong inhibition of the cdc2-specific tyrosine kinase(s). This may explain why early cell cycles are so rapid in many species.


Subject(s)
CDC2 Protein Kinase/metabolism , Cyclins/metabolism , Maturation-Promoting Factor/metabolism , Protein-Tyrosine Kinases/antagonists & inhibitors , Amino Acid Sequence , Animals , Enzyme Activation , Ethers, Cyclic/pharmacology , Humans , Interphase , Models, Biological , Molecular Sequence Data , Okadaic Acid , Phosphorylation , Protein-Tyrosine Kinases/metabolism , Tyrosine/metabolism , Vanadates/pharmacology , Xenopus
15.
EMBO J ; 11(7): 2381-90, 1992 Jul.
Article in English | MEDLINE | ID: mdl-1321030

ABSTRACT

Exit from metaphase of the cell cycle requires inactivation of MPF, a stoichiometric complex between the cdc2 catalytic and the cyclin B regulatory subunits, as well as that of cyclin A-cdc2 kinase. Inactivation of both complexes depends on proteolytic degradation of the cyclin subunit, yet cyclin proteolysis is not sufficient to inactivate the H1 kinase activity of cdc2. Genetic evidence strongly suggests that type 1 phosphatase plays a key role in the metaphase-anaphase transition of the cell cycle. Here we report that inhibition of both type 1 and type 2A phosphatases by okadaic acid allows cyclin degradation to occur, but prevents cdc2 kinase inactivation. Complete inhibition of type 2A phosphatase alone is not sufficient to prevent cdc2 kinase inactivation following cyclin proteolysis. We show further that residue 161 of cdc2 is phosphorylated in active cyclin A or cyclin B complexes at metaphase, whilst unassociated cdc2 is not phosphorylated. Proteolysis of cyclin releases a free cdc2 subunit, which subsequently undergoes dephosphorylation and then migrates more slowly than its Thr161 phosphorylated counterpart in Laemmli gels. Removal of phosphothreonine 161 requires cyclin proteolysis. However, it does not occur even after cyclin proteolysis, when both type 1 and type 2A phosphatases are inhibited. We conclude that both cyclin degradation and dephosphorylation of Thr161 on cdc2, catalysed at least in part by type 1 phosphatase, are required to inactivate either cyclin B- or cyclin A-cdc2 kinases and thus for cells to exit from M phase.


Subject(s)
Anaphase , CDC2 Protein Kinase/antagonists & inhibitors , CDC2 Protein Kinase/metabolism , Threonine/metabolism , Amino Acid Sequence , Animals , Blotting, Western , Cyclins/metabolism , Ethers, Cyclic/pharmacology , Humans , Hydrolysis , Maturation-Promoting Factor/metabolism , Metaphase , Molecular Sequence Data , Okadaic Acid , Peptide Mapping , Phosphoric Monoester Hydrolases/antagonists & inhibitors , Phosphoric Monoester Hydrolases/metabolism , Phosphorylation , Precipitin Tests , Starfish , Xenopus
16.
FEBS Lett ; 306(1): 90-3, 1992 Jul 13.
Article in English | MEDLINE | ID: mdl-1321060

ABSTRACT

Truncated cyclin A and cyclin B lacking the N-terminal domain comprising the 'destruction box' escape from proteolysis and arrest cells at metaphase. Mutation of a conserved arginine residue of the destruction domain makes cyclin B resistant to proteolysis. Here we show that mutation of the same residue also makes cyclin A resistant to proteolysis, in either of two situations in which the cyclin degradation pathway is turned on: (i) in Xenopus extracts of activated eggs where the degradation pathway has been permanently turned on by adding a recombinant undegradable cyclin B in which the arginine residue of the destruction box has been substituted by alanine; (ii) in extracts of metaphase II-arrested oocytes after Ca(2+)-dependent inactivation of the cytostatic factor (CSF).


Subject(s)
Cell Cycle , Cyclins/metabolism , Xenopus/metabolism , Adenosine Triphosphate/metabolism , Amino Acid Sequence , Animals , Blotting, Western , Cations, Divalent , Cyclins/genetics , Cysteine/genetics , Cysteine/metabolism , Magnesium/metabolism , Molecular Sequence Data , Mutation , Protamine Kinase/metabolism
17.
J Cell Sci ; 102 ( Pt 1): 55-62, 1992 May.
Article in English | MEDLINE | ID: mdl-1386852

ABSTRACT

Purified cyclin B-cdc2 kinase has been shown previously to trigger cyclin degradation in interphase frog extracts by initiating a cascade of reactions that includes cyclin ubiquitinylation and ends with proteolysis. However, cyclin A-cdc2 kinase was not assayed in these early experiments. Here we have shown that full-length recombinant human cyclin A failed to induce cyclin degradation when it was added to frog extracts free of cyclin B, although it formed an active kinase complex with Xenopus cdc2. A highly purified kinase complex containing a truncated human cyclin A and starfish cdc2 also failed to switch on the cyclin degradation pathway. In contrast, both recombinant cyclin B and highly purified cyclin B-cdc2 kinase readily triggered degradation of both cyclins B and A in frog extracts. Whilst free cyclin A had no inhibitory effect, cyclin A-cdc2 kinase delayed degradation of both cyclins A and B induced by cyclin B-cdc2 kinase. The finding that cyclin A-cdc2 kinase cannot turn on, and even delays, cyclin destruction may be essential to prevent premature inactivation of MPF (maturation-promoting factor) before complete condensation of chromosomes and formation of the metaphase spindle.


Subject(s)
CDC2 Protein Kinase/physiology , Cell Extracts/physiology , Cyclins/metabolism , Interphase/physiology , Ovum/metabolism , Animals , CDC2 Protein Kinase/pharmacology , Cell Extracts/chemistry , Cell-Free System , Cyclins/physiology , Humans , Interphase/drug effects , Oocytes/enzymology , Oocytes/metabolism , Oocytes/physiology , Ovum/enzymology , Ovum/physiology , Starfish , Xenopus/metabolism
18.
J Clin Pharmacol ; 32(2): 124-32, 1992 Feb.
Article in English | MEDLINE | ID: mdl-1613121

ABSTRACT

The disposition of a single 20-mg oral dose of pravastatin was assessed in subjects with various degrees of renal function. Sixteen subjects (13 males, 3 females) with creatinine clearance values ranging from 15 to 112 mL/min/1.73 m2 completed the study. Area under the serum concentration-time curve, maximum serum concentration, time to maximum serum concentration, terminal serum elimination half-life, apparent clearance, and apparent volume of distribution for pravastatin were not affected by renal impairment, whereas the renal clearance of pravastatin decreased as creatinine clearance decreased (r2 = 0.697, P less than .001). The area under the serum concentration-time curve and time to maximum serum concentration of SQ 31,945 (a hepatic metabolite) increased in patients with renal impairment, whereas the terminal elimination rate constant and renal clearance of SQ 31,945 significantly decreased as a function of creatinine clearance. The renal clearance of another metabolite (SQ 31,906) also significantly declined with decreasing renal function. This single-dose study demonstrates that pravastatin pharmacokinetics were not affected in patients with renal impairment, probably because of its dual route of elimination.


Subject(s)
Kidney Diseases/metabolism , Pravastatin/analogs & derivatives , Pravastatin/pharmacokinetics , Administration, Oral , Adult , Aged , Creatinine/metabolism , Drug Administration Schedule , Female , Humans , Kidney Diseases/physiopathology , Male , Metabolic Clearance Rate , Middle Aged , Pravastatin/administration & dosage , Pravastatin/metabolism
19.
Arq. bras. med ; 66(1): 63-6, jan.-fev. 1992. tab, graf
Article in Portuguese | LILACS | ID: lil-228169

ABSTRACT

A segurança da pravastatina, um inibidor seletivo hidrofílico da HMG-CoA redutase, foi avaliada em 1.142 pacientes adultos hipercolesterolêmicos em seis ensaios clínicos multicêntricos realizados nos Estados Unidos. Todos os ensaios foram aleatórios, duplo-cegos e controlados por placebo ao menos nas primeiras oito a 16 semanas, mantendo-se a seguir o tratamento a longo prazo com pravastatina em esquema duplo-cego ou aberto, com ou sem outras drogas redutoras de lipídios; o controle ativo primário foi a resina biliar de ligaçao a ácidos. Nao houve diferenças entre os grupos de pravastatina e placebo com relaçao às taxas globais de reaçoes adversas atribuíveis à droga. Somente erupçoes cutâneas (rash) ocorreram com maior freqúência estatística (p < 0,01) nos pacientes tratados com pravastina. Essas erupçoes geralmente eram leves e transitórias e somente 1,3 por cento dos casos relatados em pacientes tratados com pravastatina estavam possivelmente relacionados à terapia. Durante um período médio de tratamento de 18 meses, as razoes mais freqüentes para a interrupçao da administraçao de pravastatina foram queixas abdominais leves (1,4 por cento dos pacientes) e aumentos assintomáticos das transaminases hepáticas (1,0 por cento dos pacientes). Os valores médios de ALAT e ASAT aumentaram ligeiramente, atingindo um patamar estável após as primeiras oito semanas de terapia. Nenhuma ocorrência de enzimas hepáticas anormais entre os pacientes tratados com pravastina foi associada a doença clínica. Aumentos semelhantes das transaminases hepáticas também foram observados nos pacientes tratados com resina. Em geral, a pravastatina foi bem tolerada e aparentemente nao afetou os músculos esqueléticos, o sono ou o desenvolvimento de catarata.


Subject(s)
Humans , Male , Female , Middle Aged , Clinical Trials as Topic , Hydroxymethylglutaryl CoA Reductases/pharmacology , Pravastatin/pharmacology , Double-Blind Method , Follow-Up Studies , United States
20.
EMBO J ; 10(8): 2087-93, 1991 Aug.
Article in English | MEDLINE | ID: mdl-1829675

ABSTRACT

Exit from M phase, which requires cyclin degradation, is prevented from occurring in unfertilized eggs of vertebrates arrested at second meiotic metaphase due to a cytostatic factor recently identified as p39mos, the product of the proto-oncogene c-mos. Calpain can destroy both p39mos and cyclin in vitro in extracts prepared from metaphase-arrested Xenopus eggs, but only when free Ca2+ concentration is raised to the millimolar range. When free Ca2+ concentration is raised for only 30 s to the micromolar range, as occurs in physiological conditions after fertilization, cyclin degradation is induced, byt p39mos is not degraded. Cyclin proteolysis at micromolar free Ca2+, is not inhibited by calpastatin, and therefore does not involve calpain. A cyclin mutant modified in the destruction box is found to be resistant at micromolar, but not millimolar free Ca2+, suggesting that the ubiquitin pathway mediates cyclin degradation at micromolar Ca2+ concentration whereas calpain is involved at the millimolar level. A synthetic peptide which binds Ca(2+)-calmodulin with high affinity suppresses cyclin degradation at micromolar but not millimolar free Ca2+, and this only when it is present in the extract during the first 30 s after raising free Ca2+ concentration. The inhibition of the cyclin degradation pathway by the Ca(2+)-calmodulin binding peptide can be overcome by adding calmodulin. These results strongly suggest that a Ca(2+)-calmodulin process is required as an early event following fertilization to release the cyclin degradation pathway from inhibition in metaphase-arrested eggs. In contrast, p39mos degradation is not required.


Subject(s)
Calcium/metabolism , Calmodulin/metabolism , Cyclins/metabolism , Meiosis , Protein-Tyrosine Kinases/metabolism , Proto-Oncogene Proteins/metabolism , Animals , Autoradiography , Electrophoresis, Polyacrylamide Gel , Hydrolysis , Immunohistochemistry , Metaphase , Oocytes/cytology , Proto-Oncogene Proteins c-mos , Xenopus
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