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M R Green

Publications and source records attributed to M R Green.

At least 91 records · Page 5Linked to original sources
PubMed1998

Factors predictive of survival among 337 patients with mesothelioma treated between 1984 and 1994 by the Cancer and Leukemia Group B.

PURPOSE: To examine the individual and joint effect of various pretreatment clinical characteristics on the survival of patients with mesothelioma treated by the Cancer and Leukemia Group B (CALGB). PATIENTS AND METHODS: Between June 1984 and September 1994, 337 patients with malignant mesothelioma and no prior chemotherapy were accrued to seven phase II studies conducted by the CALGB which screened the efficacy of 10 treatment regimens or dose levels. The eligibility criteria for all studies were virtually identical. Patient characteristics include the following: age older than 60 years (63%); male (83%); performance status (PS) of 0 or 1 (81%); chest pain (60%); definite asbestos exposure (62%); >5% weight loss (41%); and pleural involvement (94%). Median survival time (MST) for the 10 treatment regimens ranged from 3.9 to 9.8 months (overall=7.2; 95% confidence interval [CI], 6.5 to 8.3), with 1-year survival between 14% and 50% (overall=27%; 95% CI, 23 to 33%). RESULTS: Cox survival models and exponential regression trees were used to examine the prognostic importance of pretreatment patient characteristics. Univariate analyses show that patients with poor Eastern Cooperative Oncology Group PS, chest pain, dyspnea, platelet count (PLT) >400,000/microL, weight loss, serum lactate dehydrogenase (LDH) level >500 IU/L, pleural involvement, low hemoglobin (HGB) level, high WBC count, and increasing age over 75 years have a worse prognosis. With decreasing risk ratio, multivariate Cox analyses showed that pleural involvement, LDH >500 IU/L, poor PS, chest pain, PLT >400,000/microL, nonepithelial histology, and increasing age older than 75 years jointly predict poor survival. PS was the most important prognostic split in the regression tree. Terminal nodes were amalgamated to form six distinct prognostic subgroups with MST (2-year survival) of 13.9 (38%) in 36 patients, 9.5 (21%) in 36 patients, 9.2 (10%) in 146 patients, 6.5 (3%) in 33 patients, 4.4 (0%) in 73 patients, and 1.4 (0%) in 13 patients (p<0.0001). CONCLUSIONS: The subgroup with the best survival (MST=13.9 months) included patients with PS=0 and age younger than 49 years, and patients with PS=0, age of 49 years or older, and HGB > or =14.6. The worst survival (MST= 1.4 months) occurred for patients with PS= 1/2 and WBC > or =15.6/microL.

Aged↗
PubMed1998

Clinical studies in non-small cell lung cancer: the CALGB experience.

Since 1984, the Cancer and Leukemia Group B (CALGB) has focused its clinical research in stage IV non-small cell lung cancer (NSCLC) on investigations of new agents and combinations. Currently, efforts are aimed at identifying non-cisplatin-based combinations with an increased therapeutic index. In stage III disease multimodality therapies have been pursued. Dillman et al. reported a study comparing standard radiotherapy versus induction chemotherapy followed by radiotherapy in patients with unresectable stage III NSCLC. The chemotherapy-treated patients were found to benefit with a 4-month increase in median survival time compared with patients receiving radiotherapy alone (13.8 vs. 9.7 months) and an increased 3-year survival rate of 23% versus 11%. This was the first randomized cooperative group study demonstrating a survival advantage resulting from the use of induction chemotherapy in locoregionally advanced NSCLC. In a subsequent study, the administration of additional "posterior" chemotherapy was not found to be feasible because of early disease progression and toxicity, while the administration of induction chemotherapy followed by concomitant chemoradiotherapy was feasible; therefore, the latter approach was studied further in a randomized phase III setting. This study compared a standard of two cycles of cisplatin and vinblastine followed by radiotherapy with an experimental arm of cisplatin and vinblastine followed by radiotherapy and concomitant carboplatin. Accrual to this study has been completed and results are expected in the near future. In resectable stage III disease, studies have focused on the optimal sequencing of multimodality therapy. A randomized study comparing standard regional therapy with radiotherapy and surgery versus a previously piloted approach combining chemotherapy, surgery, and radiotherapy was closed prematurely due to poor accrual. The next generation of studies in stage III NSCLC will focus on the integration of new chemotherapy agents into the treatment armamentarium for NSCLC. A randomized phase II study investigating paclitaxel, gemcitabine, and vinorelbine in combination with cisplatin in the induction setting and as concomitant chemoradiotherapy has recently been activated.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1998

Combined cisplatin and gemcitabine for non-small cell lung cancer: influence of scheduling on toxicity and drug delivery.

The scheduling of cytotoxic chemotherapy has important bearing on the toxicity and ability to deliver chemotherapy at or close to full dose. We report new data on the influence of different schedules of cisplatin and gemcitabine on toxicity and drug delivery in phase II studies of non-small cell lung cancer. Patients in six phase II studies had standard entry criteria for advanced non-small cell lung cancer. Whereas gemcitabine was given on days 1, 8, and 15 of a 28-day cycle in all these studies, the scheduling of cisplatin varied and was given either on day 1, day 2, day 15 (in two studies), or days 1, 8, and 15 (in two studies). The protocol dose per infusion for gemcitabine was 1,000 mg/m2 (five studies) and 1,500 mg/m2 (one study); for cisplatin, it was 100 mg/m2 when given once per cycle and 30 mg/m2 when given on days 1, 8, and 15. Similar dose reduction schedules were implemented in the event of grade 3 or higher drug toxicity for all studies except for the day 1 cisplatin study, in which the dose was omitted for grade 2 thrombocytopenia. Nonhematologic toxicity was very low. Hematologic toxicity was moderate, and in patients who developed grade 3 or 4 toxicity, there was no hemorrhage from thrombocytopenia and neutropenic sepsis was rare. The incidence of grade 3 or 4 thrombocytopenia with the day 1, day 2, day 15 (two studies combined), and days 1, 8, and 15 (two studies combined) cisplatin regimens was 50%, 52%, 26%, and 38%. The incidence of grade 3 or 4 neutropenia with these four regimens was 51%, 37%, 56%, and 49%, respectively. Although the hematologic toxicity might appear relatively similar, it represents the toxicity at the administered rather than the intended (protocol) dose, because drug delivery was reduced or omitted in the event of grade 3 or 4 toxicity. Differences between the schedules are revealed by analysis of the actual dosages delivered. The median dosage of gemcitabine per scheduled infusion was statistically higher with the day 15 cisplatin regimens (combined) compared with any of the other regimens treating at 1,000 mg/m2 (P < .003, z-score). The dose with the day 1, day 2, day 15, and days 1, 8, and 15 cisplatin regimens was 664, 829, 889, and 774 mg/m2, respectively. Both the percentages of cycles in which gemcitabine infusions were given at full dose and in which there were no omissions of gemcitabine infusions (including infusions with dose reductions) were statistically higher in the day 15 cisplatin regimen than with any of the other regimens (P < .0001, chi-square test). The percentage of cycles containing full-dose gemcitabine with the day 1, day 2, day 15, and days 1, 8, and 15 cisplatin regimens was 24%, 44%, 75%, and 46%, respectively. The percentage of cycles in which there were no omissions of gemcitabine infusions for the four regimens above was 32%, 55%, 83%, and 72%, respectively. Apart from the once-weekly regimen (days 1, 8, and 15) in which the protocol gemcitabine dose was 1,250 mg/m2, the day 15 cisplatin schedule allowed for the highest median concentration of gemcitabine. More importantly, the day 15 cisplatin schedule provided the longest duration of gemcitabine exposure, which is particularly important for its activity as gemcitabine is a phase-specific agent. The day 15 cisplatin schedule is associated with the best dose intensity and the longest median duration of exposure to gemcitabine, and best meets the goal of administering both agents at full doses in combination.

Adult↗
PubMed1997

Yeast TAF(II)145 required for transcription of G1/S cyclin genes and regulated by the cellular growth state.

TFIID comprises the TATA box-binding protein and a set of highly conserved associated factors (TAF(II)s). yTAF(II)145, the core subunit of the yeast TAF(II) complex, is dispensable for transcription of most yeast genes but specifically required for progression through G1/S. Here we show that transcription of G1 and certain B-type cyclin genes is dependent upon yTAF(II)145. At high cell density or following nutrient deprivation, yeast cells cease division, enter a G0-like state, and terminate transcription of most genes. In this stationary phase, we find that the levels of yTAF(II)145, several other yTAF(II)s, and TBP are drastically reduced. Collectively, our results indicate that yTAF(II)145 and other TFIID components have a specialized role in transcriptional regulation of cell cycle progression and growth control.

CDC28 Protein Kinase, S cerevisiae↗
PubMed1997

Yeast TAF(II)145 functions as a core promoter selectivity factor, not a general coactivator.

In yeast, TATA box binding protein associated factors (TAF(II)s) are dispensable for transcription of most genes. Here we use differential display to identify a small subset of yeast genes whose transcription in vivo requires yTAF(II)145. Promoter-mapping studies reveal, unexpectedly, that the region of a gene that renders it yTAF(II)145-dependent is not the upstream activating sequence, which contains the activator-binding sites, but rather the core promoter. In fact, a core promoter requiring yTAF(II)145 retained that requirement when its transcription was directed by several unrelated upstream activating sequences and even in the absence of an activator. Taken together, our results indicate that yTAF(II)145 functions in recognition and selection of core promoters by a mechanism not involving upstream activators.

Cell Cycle↗
PubMed1997

Identification of a human protein that recognizes the 3' splice site during the second step of pre-mRNA splicing.

Accurate splicing of precursor mRNAs (pre-mRNAs) requires recognition of the 5' and 3' splice sites at the intron boundaries. Interactions between several splicing factors and the 5' splice site, which occur prior to the first step of splicing, have been well described. In contrast, recognition of the 3' splice site, which is cleaved during the second catalytic step, is poorly understood, particularly in higher eukaryotes. Here, using site-specific photo-crosslinking, we find that the conserved AG dinucleotide at the 3' splice site is contacted specifically by a 70 kDa polypeptide (p70). The p70-3' splice site crosslink has kinetics and biochemical requirements similar to those of splicing, was detected only in the mature spliceosome and occurs subsequent to the first step. Thus, p70 has all the properties expected of a factor that functionally interacts with the 3' splice site during the second step of splicing. Using antisera to various known splicing factors, we find that p70 corresponds to a previously reported 69 kDa protein of unknown function associated with the Sm core domain of spliceosomal small nuclear ribonucleoproteins.

Cross-Linking Reagents↗
PubMed1997

U2AF65 recruits a novel human DEAD box protein required for the U2 snRNP-branchpoint interaction.

Splicing of mRNA precursors (pre-mRNAs) comprises a series of ATP-dependent steps, the first of which is the stable binding of U2 snRNP at the pre-mRNA branchpoint. The basis of ATP use for the interaction between U2 snRNP and the branchpoint is unclear, and, in particular, none of the known mammalian factors required for this step have the sequence characteristics of proteins that hydrolyze ATP. Entry of U2 snRNP into the spliceosome is initiated by interaction of the essential splicing factor U2AF65 with the pre-mRNA polypyrimidine tract. In this report we identify a new region of U2AF65 required for function, and use this information to clone a human 56-kD U2AF65 associated protein (UAP56). We show that UAP56 is an essential splicing factor, which is recruited to the pre-mRNA dependent on U2AF65, and is required for the U2 snRNP-branchpoint interaction. The sequence of UAP56 indicates it is a member of the DEAD box family of RNA-dependent ATPases, which mediate ATP hydrolysis during several steps of yeast pre-mRNA splicing. Our results reveal a new function of U2AF65: to position a DEAD box protein required for U2 snRNP binding at the pre-mRNA branchpoint region.

Adenosine Triphosphatases↗
PubMed1997

Distinct mechanisms of splicing regulation in vivo by the Drosophila protein Sex-lethal.

The protein Sex-lethal (SXL) controls pre-mRNA splicing of two genes involved in Drosophila sex determination: transformer (tra) and the Sxl gene itself. Previous in vitro results indicated that SXL antagonizes the general splicing factor U2AF65 to regulate splicing of tra. In this report, we have used transgenic flies expressing chimeric proteins between SXL and the effector domain of U2AF65 to study the mechanisms of splicing regulation by SXL in vivo. Conferring U2AF activity to SXL relieves its inhibitory activity on tra splicing but not on Sxl splicing. Therefore, antagonizing U2AF65 can explain tra splicing regulation both in vitro and in vivo, but this mechanism cannot explain splicing regulation of Sxl pre-mRNA. These results are a direct proof that Sxl, the master regulatory gene in sex determination, has multiple and separable activities in the regulation of pre-mRNA splicing.

Animals↗
PubMed1997

Targeting of U2AF65 to sites of active splicing in the nucleus.

U2AF65 is an essential splicing factor that promotes binding of U2 small nuclear (sn)RNP at the pre-mRNA branchpoint. Here we describe a novel monoclonal antibody that reacts specifically with U2AF65. Using this antibody, we show that U2AF65 is diffusely distributed in the nucleoplasm with additional concentration in nuclear speckles, which represent subnuclear compartments enriched in splicing snRNPs and other splicing factors. Furthermore, transient expression assays using epitope-tagged deletion mutants of U2AF65 indicate that targeting of the protein to nuclear speckles is not affected by removing either the RNA binding domain, the RS domain, or the region required for interaction with U2AF35. The association of U2AF65 with speckles persists during mitosis, when transcription and splicing are downregulated. Moreover, U2AF65 is localized to nuclear speckles in early G1 cells that were treated with transcription inhibitors during mitosis, suggesting that the localization of U2AF65 in speckles is independent of the presence of pre-mRNA in the nucleus, which is consistent with the idea that speckles represent storage sites for inactive splicing factors. After adenovirus infection, U2AF65 redistributes from the speckles and is prefferentially detected at sites of viral transcription. By combining adenoviral infection with transient expression of deletion mutants, we show a specific requirement of the RS domain for recruitment of U2AF65 to sites of active splicing in the nucleus. This suggests that interactions involving the RS region of U2AF65 may play an important role in targeting this protein to spliceosomes in vivo.

Amino Acid Sequence↗
PubMed1997

Dihydro-5-azacytidine in malignant mesothelioma. A phase II trial demonstrating activity accompanied by cardiac toxicity. Cancer and Leukemia Group B.

BACKGROUND: Malignant mesothelioma is a disease that is refractory to chemotherapy. Therefore, the objective of this multi-institutional, cooperative group Phase II trial was to determine the efficacy of dihydro-5-azacytidine (DHAC), a pyrimidine analogue, in the treatment of malignant mesothelioma. METHODS: Forty-one patients with histologically confirmed malignant mesothelioma received 120-hour continuous infusions of DHAC (1,500 mg/m2/day every 21 days) until maximal response, intolerable toxicity, or disease progression. RESULTS: One patient had a complete response, two had objective partial responses, and four had regression of evaluable disease. The overall response rate was 17%. The one complete responder remains without disease progression at 6 years. Chest pain and nausea were the most common toxicities. Supraventricular tachycardia and pericardial effusion occurred in 20% and 15% of patients, respectively. In most patients, gastrointestinal effects were manageable. There was no significant hematologic toxicity. CONCLUSIONS: In malignant mesothelioma, a disease that is refractory to chemotherapy, dihydro-5-azacytidine has definite antitumor activity. Its modest hematologic toxicity profile favors its use in combination with other agents. Caution regarding cardiac arrhythmias and pericardial effusion is necessary.

Adult↗
PubMed1997

Functional antagonism between RNA polymerase II holoenzyme and global negative regulator NC2 in vivo.

Activation of eukaryotic class II gene expression involves the formation of a transcription initiation complex that includes RNA polymerase II, general transcription factors, and SRB components of the holoenzyme. Negative regulators of transcription have been described, but it is not clear whether any are general repressors of class II genes in vivo. We reasoned that defects in truly global negative regulators should compensate for deficiencies in SRB4 because SRB4 plays a positive role in holoenzyme function. Genetic experiments reveal that this is indeed the case: a defect in the yeast homologue of the human negative regulator NC2 (Dr1 x DRAP1) suppresses a mutation in SRB4. Global defects in mRNA synthesis caused by the defective yeast holoenzyme are alleviated by the NC2 suppressing mutation in vivo, indicating that yeast NC2 is a global negative regulator of class II transcription. These results imply that relief from repression at class II promoters is a general feature of gene activation in vivo.

Amino Acid Sequence↗
PubMed1997

YY1 regulates vitamin D receptor/retinoid X receptor mediated transactivation of the vitamin D responsive osteocalcin gene.

The responsiveness of genes to steroid hormones is principally mediated by functional interactions between DNA-bound hormone receptors and components of the transcriptional initiation machinery, including TATA-binding protein, TFIIB, or other RNA polymerase II associated factors. This interaction can be physiologically modulated by promoter context-specific transcription factors to facilitate optimal responsiveness of gene expression to hormone stimulation. One postulated regulatory mechanism involves the functional antagonism between hormone receptors and nonreceptor transcription factors interacting at the same hormone response element. Here we demonstrate that the multifunctional regulator YY1 represses 1,25-dihydroxyvitamin D3 (vitamin D)-induced transactivation of the bone tissue-specific osteocalcin gene. We identify YY1 recognition sequences within the vitamin D response element (VDRE) of the osteocalcin gene that are critical for YY1-dependent repression of vitamin D-enhanced promoter activity. We show that YY1 and vitamin D receptor (VDR)/retinoid X receptor heterodimers compete for binding at the osteocalcin VDRE. In addition, we find that YY1 interacts directly with TFIIB, and that one of the two tandemly repeated polypeptide regions of TFIIB spanning the basic domain is responsible for this interaction. TFIIB and VDR can also interact directly, and these factors synergize to mediate transactivation. Our results suggest that YY1 regulates vitamin D enhancement of osteocalcin gene transcription in vivo by interfering with the interactions of the VDR with both the VDRE and TFIIB.

Animals↗
PubMed1997

High-energy collision-induced fragmentation of complex oligosaccharides ionized by matrix-assisted laser desorption/ionization mass spectrometry.

The high-energy CID spectra of the MNa+ ions from 17 underivatized oligosaccharides of the type found attached to asparagine in glycoproteins were examined with a double-focusing mass spectrometer fitted with a tandem orthogonal time-of-flight analyser. Fragment ions were observed throughout the mass range from all compounds and provided considerable structural information in the low-picomole range. The three types of fragmentation that were observed were glycosidic cleavages, cross-ring cleavages and the formation of internal cleavage ions. The major glycosidic fragmentations were B- and Y-type cleavages (Domon and Costello nomenclature). B-cleavages were particularly abundant at GlcNAc residues. Z-ions were absent when glycosidic linkages occurred at the 6-position. Cross-ring cleavages were predominantly of the 1,5X-type, which provided much sequence and branching information. 3,5A cleavages of the core branching mannose residue were often prominent and provided information on the composition of each of the main antennae. Antenna composition was also reflected by a major internal fragment ion formed by elimination of the two GlcNAc residues of the chitobiose core together with the entire antenna at the 3-position of the core branching mannose residue. A further loss of GlcNAc as 221 mass units from this ion in the spectra of the hybrid and complex carbohydrates was indicative of the presence of a "bisecting' (4-linked) GlcNAc substituent. Another prominent internal fragment ion containing a mannose residue and only one GlcNAc, with its substituents, was present in the spectra of the complex sugars when branching of the 3-antenna occurred.

Acetylglucosamine↗
PubMed1997

A longitudinal study of quality of life in advanced non-small cell lung cancer: Cancer and Leukemia Group B (CALGB) 8931.

A quality of life (QOL) endpoint supplemented standard clinical endpoints of survival, tumor response, and toxicity in a double-blind study conducted by the Cancer and Leukemia Group B (CALGB) where 291 patients with advanced non-small cell lung cancer (NSCLC) were randomly assigned to receive cisplatin/vinblastine with either hydrazine sulfate (HS) or placebo. The difficulties associated with the analysis of the longitudinal QOL data, and the contributions that the QOL endpoint made to the understanding of treatment differences, will be the focus of this paper.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1997

Intensity of neoadjuvant therapy in resectable non-small cell lung cancer.

Induction chemotherapy prior to definitive local treatment improves the survival of patients with Stage III non-small cell lung cancer. Several strategies to improve on the impact of 2 or 3 cycles of conventional induction chemotherapy are under study. Immediate concurrent chemoradiation followed by surgery has been evaluated extensively in the Phase II setting. This approach is now the subject of a Phase III trial in North America. Increasing the number of induction chemotherapy cycles or using high dose chemotherapy with autologous stem cell support are other strategies currently under evaluation. Understanding whether either of these approaches will improve survival for patients with Stage III NSCLC must await future Phase III trials.

Carcinoma, Non-Small-Cell Lung↗
PubMed1997

Modulation of the Rev-RRE interaction by aromatic heterocyclic compounds.

The HIV-1 Rev protein regulates the nucleocytoplasmic distribution of viral precursor RNAs that encode HIV-1 structural proteins. Rev-mediated viral RNA expression requires a sequence-specific interaction between Rev and a viral RNA sequence, the Rev responsive element (RRE). Because the Rev-RRE interaction is essential for HIV-1 replication, anti-viral agents that selectively block this interaction may be effective anti-HIV-1 therapeutics. Here, we show that certain aromatic heterocyclic compounds, in particular, a tetracationic diphenylfuran, AK.A, can block binding of Rev to its high-affinity viral RNA binding site. AK.A abolishes Rev-RRE interactions at concentrations as low as 0.1 microM. Inhibition appears to be selective and results from competitive binding of the drug to a discrete region within the Rev binding site. Interestingly, the molecular basis for the AK.A-RNA interaction, as well as the mode of RNA binding differs from previously described aminoglycoside Rev inhibitors. Analysis of a variety of aromatic heterocyclic compounds and their derivatives reveals stereo-specific features required for the inhibition. Our results further demonstrate the feasibility of identifying and designing small molecules that selectively block viral RNA-protein interactions.

Aminoglycosides↗
PubMed1997

The epidermal nerve fibre network: characterization of nerve fibres in human skin by confocal microscopy and assessment of racial variations.

As a first line of defence, the skin is equipped with a complex and interactive nerve fibre system to detect irritants and maintain homeostasis. The dermal component of this fibre network has been well characterized and fibres are known to extend throughout the viable epidermis as free nerve endings. To date, this epidermal component remains poorly characterized. We have visualized human volar forearm epidermal nerve fibres by laser-scanning confocal microscopy using the pan-neuronal marker, protein gene-product 9.5 and specific antibodies to substance P. calcitonin gene-related peptide and nerve growth factor. In addition to the varicose free nerve endings, there is a 3-D fibre network in normal human epidermis, with frequent branching of fibres. Branching can be seen to converge on a central trunk apparently extending to the dermis. Thin unmyelinated fibres can be seen in all layers of the viable epidermis. Substance P staining is rarely observed and is much less intense than the protein gene-product 9.5 staining. Calcitonin gene-related peptide and nerve growth factor were not detected in volar forearm epidermis by this method. Pretreatment of the skin in vivo with the neuropharmacological agent, capsaicin, resulted in loss of epidermal fibre staining indicating that these are sensory fibres of the primary C-afferent type. Epidermal innervation in racial and ethnic skin types was also assessed. No apparent difference in innervation was observed between European caucasian and Japanese/Chinese skin at the architectural or biochemical level, i.e. the presence, properties and biochemical content of fibres was similar in all cases tested.

Asian People↗