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Biomedical subjects

Donald M Miller

Publications and source records attributed to Donald M Miller.

13 recordsLinked to original sources
PubMed2006

A phase II study of extended dose temozolomide and thalidomide in previously treated patients with metastatic melanoma.

PURPOSE: To assess the efficacy and tolerability of extended dose temozolomide and continuous thalidomide in patients with advanced metastatic cutaneous melanoma. PATIENTS AND METHODS: Eligibility criteria included adults with histologic diagnosis of metastatic melanoma with adequate organ function and performance status. Temozolomide (75 mg/m(2)/day) was administered for 6 weeks followed by a 2-week rest. Thalidomide (200 mg/day) was given for the first 2 weeks and increased by 100 mg/day at weekly intervals up to a maximum of 400 mg/day, if no toxicity. For patients older than 70 years, thalidomide was started at 100 mg/day and the dose was increased by 50 mg/day up to a maximum of 250 mg/day. RESULTS: Twenty-six extensively pretreated subjects, with poor prognostic factors, were entered into this study and included in all analyses. According to the RECIST criteria, one (4%) subject achieved a complete response (CR), two (8%) partial response (PR), and five (19%) stable disease (SD), for a response rate (CR + PR) of 12% [95% confidence interval (CI), 0-24.7%] and a clinical benefit (CR + PR + SD) of 31%. Median time to progression was 1.8 months (95% CI, 1.2-2.4 months) and median survival was 5.2 months (95% CI, 4.1-6.2 months). CONCLUSIONS: The combination of temozolomide and thalidomide is well tolerated in patients with very advanced heavily pretreated metastatic melanoma. It has modest activity in this population with grave prognosis.

Adult↗
PubMed2006

Advantages of ProSeal and SLIPA airways over tracheal tubes for gynecological laparoscopies.

PURPOSE: To compare the efficacy of the ProSeal LMA and SLIPA supralaryngeal airways (SLA) with the standard tracheal tube (TT) in 150 consecutive day-case laparoscopic gynecological surgery procedures requiring general anesthesia. METHODS: One hundred and fifty patients were randomized into three groups. An identical general anesthesia technique was used in all patients apart from the addition of muscle relaxants and reversal drugs in the TT group. Patients were excluded if there were risk factors for gastroesophageal reflux. Ease of use, quality of seal, ventilation, systolic pressure, response to intubation, side effects and operating room time were assessed. RESULTS: Both ProSeal LMA and SLIPA were easy to insert (100% success) and ventilate with respective mean (standard deviation) maximum sealing pressures of 31 (4.6) and 30 (5.2) cmH2O (P = 0.4) with no muscle relaxants. The seal quality in both ProSeal LMA and SLIPA permitted the use of low flows, 485 (291) and 539 (344) mL x min(-1) (P = 0.2) respectively, although in the TT group significantly lower flows [377 (124) mL x min(-1)], (P < 0.01) were achieved. Systolic pressure in the SLA groups was more stable in response to insertion than in the TT. With ProSeal there was a lower incidence of sore throats than with TT (30% vs 57%), (P < 0.05), but there was a lesser difference as compared with SLIPA (30% vs 49%), (P > 0.05). With both SLAs, there was a significant reduction in operating room time (> three minutes), (P < 0.001). CONCLUSIONS: These results suggest that the ProSeal LMA (reusable) and SLIPA (single-use) SLAs were easy to use without requiring muscle relaxants, and reduce operating room time compared to the TT technique in day case laparoscopies.

Adult↗
PubMed2004

A proposed classification and scoring system for supraglottic sealing airways: a brief review.

We provide an approach to evaluating sealing supraglottic airways by using a classification based on a sealing mechanism. Three main sealing mechanisms are identified, thus defining three groups: cuffed perilaryngeal sealers, cuffed pharyngeal sealers, and uncuffed anatomically preshaped sealers. We provide a brief overview of supraglottic airways and present a scoring system that is relevant to particular requirements. Scoring airways for routine applications is the example provided.

Anesthesiology↗
PubMed2003

Inhibition of tumorigenicity by the 5'-untranslated RNA of the human c-myc P0 transcript.

Activity of the independently regulated human c-myc P0 promoter has been associated with the undifferentiated status of leukemia cells as well as the hormone-independent proliferation of breast cancer cells. The P0 transcript is distinguished from the predominant P1 and P2 c-myc mRNAs by an approximately 639-nucleotide extension of the 5'-untranslated region. We hypothesized that this complex 5'-untranslated RNA sequence unique to the P0 transcript may contribute significantly to the composite regulation of the c-myc locus and that enforced intracellular synthesis of the isolated P0 5'-UTR, out of its native sequence context, might amplify or dominantly interfere with its normal regulatory function. Human tumor (HeLa) cells in which the isolated P0 5'-UTR was ectopically expressed displayed a dramatic decrease in anchorage-independent proliferation. Furthermore, P0 5'-UTR-expressing HeLa cells failed to form tumors when inoculated into SCID mice. This loss of tumorigenicity was associated with increases in levels of the c-Myc1 (p67) and c-Myc2 (p64) proteins and a 3- to 5-fold elevation of spontaneous apoptotic index. These results demonstrate that an isolated 5'-untranslated RNA sequence can be attributed potent in trans gene-regulatory and phenotype-altering capabilities and that extrinsic alterations in c-myc regulation can be utilized to reestablish the natural proapoptotic (tumor suppressor) activities associated with this protooncogene.

5' Untranslated Regions↗
PubMed2003

Identification of distinct gene expression profiles associated with treatment of LbetaT2 cells with gonadotropin-releasing hormone agonist using microarray analysis.

Gonadotropin-releasing hormone (GnRH) is a neuropeptide that plays a pivotal role in reproductive processes. In recent years, it has become clear that it is also an anti-proliferative agent. GnRH analogs are now used clinically in the treatment of prostate cancer as well as endometriosis and precocious puberty. The target cells of GnRH include the gonadotropes of the anterior pituitary gland and the cells of various hormone-dependent tumors. Only a few target genes have been identified in these cells, however, and little is known concerning their regulation by GnRH. Therefore, we used a quantitative microarray assay to identify the genes that are regulated by GnRH in a murine gonadotrope tumor cell line (LbetaT2). Treatment of LbetaT2 cells with GnRH agonist des-gly(10),[D-Ala(6)]GnRH (GnRHA) for 1 h resulted in alterations in the levels of expression of genes that ranged in magnitude from 1.3- to 159-fold, with a total of 232 genes exhibiting a twofold or greater alteration in expression compared to vehicle treated cells. Of these 232 genes, 149 were up-regulated and, surprisingly, 83 were down-regulated by GnRHA treatment. After 24 h of treatment, the expression of most of the genes that had exhibited altered expression after 1 h of treatment had returned to baseline levels. Moreover, a different profile was observed after 24 h of treatment with 208 genes exhibiting a twofold or greater alteration. Of these, 95 were up-regulated and 113 down-regulated. Most of the affected genes were not known to be responsive to GnRH prior to this study. Treatment with GnRHA was found to affect the expression of a diverse range of genes, including oncogenes and those that encode transcription factors, ion channel proteins, and cytoskeletal proteins as well as other proteins that are involved in signal transduction, the cell cycle, cell proliferation and apoptosis. The altered expression of six of the genes that were found by microarray analysis to be regulated by GnRHA was confirmed by semiquantitative reverse transcriptase-polymerase chain reaction. This is first application of the microarray technique in the study of the global profile of genes regulated by GnRH, and should prove to be a powerful tool for future analysis of the mechanisms by which GnRH regulates the expression of gonadotropins and the growth of tumor cells.

Animals↗
PubMed2003

Evidence for differential ribonucleoprotein complex assembly in vitro on the 5'-untranslated region of the human IGF-IR transcript.

The type I insulin-like growth factor receptor (IGF-IR) plays a key role in the control of cellular proliferation and survival. The human IGF-IR transcript is characterized by an unusually long 1038 nucleotide 5'-untranslated region (5'-UTR). We hypothesized that the contribution of this complex 5'-untranslated RNA sequence to the post-transcriptional regulation of IGF-IR expression would involve a dynamic interplay between RNA structure and specific RNA-binding proteins. Here we have detected and characterized a diverse series of regulatory proteins binding the IGF-IR 5'-UTR under disparate conditions. One pair of proteins ( approximately 42/38 kDa) binds readily to the intact 5'-UTR, which is predicted to adopt a highly base-paired, highly favorable (dG=-498 kcal/mol) three-domain structure. Another protein(s) (p20*) specifically induces formation of a novel RNA structure from within the initial 209 nucleotides of the nascent IGF-IR transcript, but fails to UV crosslink to this RNA sequence. A third group of proteins recognizes and binds the IGF-IR 5'-UTR under highly stringent conditions, but only after higher-ordered RNA structure has been disrupted. Our in vitro results indicate that the IGF-IR 5'-UTR may exist in at least three distinct states, and we propose that interconversion between these states might take place in vivo and differentially alter IGF-IR transcript utilization.

5' Untranslated Regions↗
PubMed2003

Storage capacities of the laryngeal mask and laryngeal tube compared and their relevance to aspiration risk during positive pressure ventilation.

IMPLICATIONS: Supraglottic airways used for positive pressure ventilation run the occasional risk of regurgitated liquid entering the lungs (aspiration). A dynamic model described here shows that the laryngeal tube has a larger liquid storage capacity between the two cuffs than the bowl of the laryngeal mask, with a consequent smaller aspiration risk.

Intubation, Intratracheal↗
PubMed2002

Apoptosis in leukemia cells is accompanied by alterations in the levels and localization of nucleolin.

Molecular defects in apoptotic pathways are thought to often contribute to the abnormal expansion of malignant cells and their resistance to chemotherapy. Therefore, a comprehensive knowledge of the mechanisms controlling induction of apoptosis and subsequent cellular disintegration could result in improved methods for prognosis and treatment of cancer. In this study, we have examined apoptosis-induced alterations in two proteins, nucleolin and poly(ADP-ribose) polymerase-1 (PARP-1), in U937 leukemia cells. Nucleolin is expressed at high levels in malignant cells, and it is a multifunctional and mobile protein that can shuttle among the nucleolus, nucleoplasm, cytoplasm, and plasma membrane. Here, we report our findings that UV irradiation or camptothecin treatment of U937 cells induced apoptosis and caused a significant change in the levels and localization of nucleolin within the nucleus. Additionally, nucleolin levels were dramatically decreased in extracts containing the cytoplasm and plasma membrane. These alterations could be abrogated by pre-incubation with an inhibitor of PARP-1 (3-aminobenzamide), and our data support a potential role for nucleolin in removing cleaved PARP-1 from dying cells. Furthermore, both nucleolin and cleaved PARP-1 were detected in the culture medium of cells undergoing apoptosis, associated with particles of a size consistent with apoptotic bodies. These results indicate that nucleolin plays an important role in apoptosis, and could be a useful marker for assessing apoptosis or detecting apoptotic bodies. In addition, the data provide a possible explanation for the appearance of nucleolin and PARP-1 autoantibodies in some autoimmune diseases.

Apoptosis↗
PubMed2002

Biosensor detection of triplex formation by modified oligonucleotides.

Due to the instability of DNA oligonucleotides in biological solutions, antisense or antigene therapies aimed at modulation of specific gene expression will most likely require the use of oligonucleotides with modified backbones. Here, we examine the use of a surface plasmon resonance biosensor (BIAcore) to compare triplex-directed binding of modified oligonucleotides targeted to a region of the murine c-myc promoter. We describe optimization of experimental conditions to minimize nonspecific interactions between the oligonucleotides and the sensor chip surface, and the limitations imposed by certain backbones and sequence types. The abilities of pyrimidine oligonucleotides with various modified backbones to form specific triple helices with an immobilized hairpin duplex were readily determined using the biosensor. Modification of the third-strand oligonucleotide with RNA or 2(')-O-methyl RNA was found to enhance triplex formation, whereas phosphorothioate or phosphotriester substitutions abrogated it. A comparison of these results to DNase I footprinting experiments using the same oligonucleotides showed complete agreement between the two sets of data.

DNA↗
PubMed2002

Acridine-modified, clamp-forming antisense oligonucleotides synergize with cisplatin to inhibit c-Myc expression and B16-F0 tumor progression.

The c-myc protooncogene plays a key role in the abnormal growth regulation of melanoma cells. We have targeted three polypurine sequences within the mouse myc mRNA with acridine-modified, clamp-forming antisense oligonucleotides (AS ODNs) in an effort to inhibit growth of murine melanoma cells. These ODNs are unique in that they hybridize to the target mRNA by both Watson-Crick and Hoogsteen hydrogen bond interactions, forming a triple-stranded structure. At a concentration of 3 microM E1C, E2C and E3C inhibit B16-F0 proliferation by 76, 66 and 78%, respectively. Both immunofluorescent staining and western blot analysis corroborate a proportional reduction in c-Myc expression by all three ODNs. There were clear distinctions in the ability of these ODNs to inhibit tumor progression in C57BL/6 mice as a function of Myc expression. There was no synergy demonstrated between ODN E1C with cisplatin (DDP), which inhibited tumor growth by 77% alone and 82% in combination. Although E2C inhibited growth by 54%, its effect was decreased to 32% with DDP, when compared with controls. E3C, on the other hand, demonstrated a synergistic effect with DDP, inhibiting growth by 72% in combination, but only by 1% as a single agent. Immunofluorescence analysis of tumors for each group revealed a concomitant reduction in c-Myc expression in tumors from mice treated with the most active clamp ODN alone (E1C) or clamp ODN + DDP (E1C/E3C + DDP). Western blot analysis confirmed this decrease in target protein expression. Our results document the growth-inhibitory activity of two myc-targeting antisense clamp ODNs; E1C, which has activity as a single agent, and E3C, which has in vivo synergy with DDP pretreatment. These data confirm the antiproliferative effects of these novel ODNs and document an interesting synergy with the chemotherapeutic agent DDP.

Acridines↗
PubMed2002

Antiproliferative activity of G-quartet-forming oligonucleotides with backbone and sugar modifications.

Oligonucleotide-based therapies have considerable potential in cancer, viral, and cardiovascular disease therapies. However, it is becoming clear that the biological effects of oligonucleotides are not solely due to the intended sequence-specific interactions with nucleic acids. Oligonucleotides are also capable of interacting with numerous cellular proteins owing to their polyanionic character or specific secondary structure. We have examined the antiproliferative activity, protein binding, and G-quartet formation of a series of guanosine-rich oligonucleotides, which are analogues of GRO29A, a G-quartet forming, growth-inhibitory oligonucleotide, whose effects we have previously described [Bates P. J., Kahlon, J. B., Thomas, S. D., Trent, J. O., and Miller, D. M. (1999) J. Biol. Chem. 274, 26369-26377]. The GRO29A analogues include phosphorothioate (PS29A), 2'-O-methyl RNA (MR29A), and mixed DNA/2'-O-methyl RNA (MRdG29A) oligonucleotides. We demonstrate by UV spectroscopy that all of the modified analogues form stable structures, which are consistent with G-quartet formation. We find that the phosphorothioate and mixed DNA/2'-O-methyl analogues are able to significantly inhibit proliferation in a number of tumor cell lines, while the 2'-O-methyl RNA has no significant effects. Similar to the original oligonucleotide, GRO29A, the growth inhibitory oligonucleotides were able to compete with the human telomere sequence oligonucleotide for binding to a specific cellular protein. The less active MR29A does not compete significantly for this protein. On the basis of molecular modeling of the oligonucleotide structures, it is likely that the inactivity of MR29A is due to the differences in the groove structure of the quadruplex formed by this oligonucleotide. Interestingly, all GRO29A analogues, including an unmodified DNA phosphodiester oligonucleotide, are remarkably resistant to nuclease degradation in the presence of serum-containing medium, indicating that secondary structure plays an important role in biological stability. The remarkable stability and strong antiproliferative activity of these oligonucleotides confirm their potential as therapeutic agents.

Base Sequence↗
PubMed2002

Importance of Sp1 consensus motifs in the MYCN promoter.

BACKGROUND: MYCN (N-myc) amplification in neuroblastoma is associated with poor clinical outcome. Factors that regulate MYCN expression have not been elucidated. MYCN is considered a TATA-less promoter, whereas significant promoter activity resides within 160 bp 5' of the major transcription start site. This region contains two GC-rich motifs and a CT box, regions for potential transcription factor interaction. METHODS: To characterize DNA-protein interactions in this region of the MYCN promoter, electrophoretic mobility shift assays, and promoter-reporter were used. RESULTS: A MYCN promoter fragment was incubated with HeLa nuclear extract, with or without competitors. Three major protein/DNA complexes were formed. Formation of 2 complexes could be inhibited by unlabeled Sp1 consensus duplex and by the Sp1 site-specific drug WP631. Purified Sp1 protein produced a complex similar to that formed with HeLa extract. To determine whether these DNA/protein interactions could be blocked in a sequence-specific fashion, a triplex forming oligonucleotide (TFO) was used. This TFO was designed to bind in the major groove of the promoter, covering the CT-box (putative Sp1 binding) motif. When triplex formation was followed by addition of nuclear extract, protein binding was indeed inhibited. Functional significance of this inhibition was tested with pE/Bnmyc-luc, a promoter-reporter plasmid containing the human MYCN promoter driving luciferase expression. Incubation with TFO, but not control oligodeoxynucleotides, completely inhibited luciferase activity. CONCLUSIONS: These data suggest that protein binding does occur in regions of the MYCN promoter containing GC and CT box elements and that this interaction is important for MYCN promoter activity. By inference, these data also suggest that the proteins that bind in this region are Sp1 family members.

Base Sequence↗