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J Hamm

Publications and source records attributed to J Hamm.

At least 37 records · Page 2Linked to original sources
PubMed2001

Study of the K(0)(L) --> pi(+)pi(-)gamma Direct Emission Vertex.

We have performed studies of the K(0)(L)-->pi(+)pi(-)gamma direct emission ( DE) and inner Bremsstrahlung ( IB) vertices, based on data collected by KTeV during the 1996 Fermilab fixed target run. We find a(1)/a(2) = -0.737+/-0.034 GeV2 for the DE form-factor parameter in the rho-propagator parametrization, and report on fits of the form factor to linear and quadratic functions as well. We concurrently measure gamma(K(0)(L)-->pi(+)pi(-)gamma,E(*)(gamma)>20 MeV)/gamma(K(0)(L)-->pi(+)pi(-)) = (20.8+/-0.3)x10(-3), and a K(0)(L)-->pi(+)pi(-)gamma DE/(DE+IB) branching ratio of 0.683+/-0.011.

Journal Article↗
PubMed2000

Anti-idiotype RNAs that mimic the leucine-rich nuclear export signal and specifically bind to CRM1/exportin 1.

BACKGROUND: Anti-idiotype approaches are based on the assumption that an antibody recognising a ligand can be structurally related to the receptor. Recently we have generated anti-idiotype RNA aptamers designed to mimic the human immunodeficiency virus-1 (HIV-1) Rev nuclear export signal (NES). Nuclear injection of either NES-peptide conjugates or aptamer causes the inhibition of Rev-mediated export. This implied that NES mimics and export substrate might compete for binding to the NES receptor. The mechanism of inhibition, however, is unknown. RESULTS: The interaction between the export aptamer and CRM1 was characterised in vitro. The aptamer binds specifically to CRM1 and this interaction is sensitive to competition by Rev NES-peptide conjugates. The recognition domain of CRM1 has been mapped and includes residues found previously to affect binding of leptomycin B, a fungicide interfering with nuclear export. CONCLUSIONS: Inhibition of Rev-mediated export in vivo by export aptamers appears to result from the binding of the aptamers to the NES-recognition domain of CRM1. This observation demonstrates that anti-idiotype RNA can mimic faithfully structural and functional properties of a protein and can be used to map ligand-binding domains of receptors.

Antibiotics, Antineoplastic↗
PubMed1998

Evaluation of two intervention strategies to stimulate quality improvement projects in the hospital: the H. pylori example.

A multistate quality improvement project conducted to improve the care of hospitalized Medicare patients with peptic ulcer disease is described. This randomized control study design compared the effectiveness of two intervention strategies (mailed information vs. on-site presentations with feedback) in stimulating hospitals to conduct diagnostic journeys to determine root causes for performance deficits and to develop and implement plans to improve performance.

Aged↗
PubMed1997

Anti-idiotype RNA selected with an anti-nuclear export signal antibody is actively transported in oocytes and inhibits Rev- and cap-dependent RNA export.

The anti-idiotype approach is based on the assumption that an antibody specific for a receptor-binding domain of a ligand could be structurally related to the receptor. Therefore, a structural mimic of a receptor-binding domain, selected with an anti-ligand antibody, might be a functional substrate for the receptor. This hypothesis was addressed here by generating antibodies recognizing the Rev-nuclear export signal (NES). A functional NES is required for active export, presumably by interacting directly or indirectly with the nuclear pore complex. Anti-NES antibodies were used to isolate RNA mimics of the NES peptide from combinatorial RNA libraries. The RNA-mimics are exported actively, block Rev-dependent export of a reporter RNA, and inhibit cap-dependent U1 snRNA export in Xenopus oocytes, properties previously reported for NES-peptide conjugates.

Animals↗
PubMed1996

Characterisation of antibody-binding RNAs selected from structurally constrained libraries.

Constrained RNA libraries of limited sequence complexity were constructed and used to select RNA molecules binding to the antigen binding site of an anti-ferritin antibody. The sequences required as primer-binding sites for the selection cycle were designed to form a predictable secondary structure, which greatly facilitated the characterisation of the secondary structures of the selected RNAs. RNA-antibody interactions were studied by real-time interaction analysis to study the dynamic aspects of binding and by circular dichroism spectroscopy to search for conformational changes upon binding. The selected RNAs were analysed with a binding site sequestering assay and were shown to compete with ferritin for binding to the antigen-binding site. The experiments described here indicate that the introduction of strong structural constraints does not have to interfere with the ability to select tightly and specifically binding RNA-molecules.

Antibodies↗
PubMed1995

Rotated object identification with and without orientation cues.

The time to name two-dimensional line drawings of objects increases linearly for object rotations between 0 degrees and 120 degrees from the upright. Several theories attribute these effects of orientation to finding the top or the top-bottom axis of objects. By this account, prior knowledge of the location of the top or the top-bottom axis of objects should diminish effects of object orientation when they are named. When this hypothesis was tested by cuing the top or the top-bottom axis, no reduction in the effects of orientation on object naming was found. This result is inconsistent with effects of orientation on object naming being due to finding the top or the top-bottom axis. Instead, the top may be found prior to rotational normalization of the object image.

Humans↗
PubMed1995

Phase II trial of 5-fluorouracil, folinic acid, and N,N1,N11-triethylenethiophosphoramide (thiotepa) in patients with advanced breast cancer.

A total of 35 women with advanced, metastatic breast cancer were treated with combination chemotherapy consisting of folinic acid 500 mg/m2 over 2 hours administered with 600 mg/m2 of 5FU at the midpoint of the folinic acid infusion weekly for 6 weeks, plus 60 mg/m2 of thiotepa on day 1 and day 28. The cycle was repeated every 8 weeks. Patients were evaluated for toxicity weekly. Response was evaluated at the end of each 8-week cycle. The median age was 55 years (range: 34-67). Prior to this study 30 patients had received chemotherapy; 13 had 1 regimen; 17 had 2 or more regimens; 8 had 5FU treatment. The overall response rate was 40% (1 complete and 13 partial); median duration of response was 4 months. Four of 8 patients with prior 5FU responded. Hematologic toxicity was significant; nadir WBC count: < 1,000/mm3 (10 patients); 1,000-1,999/mm (13 patients); nadir platelet count: < 20,000/mm3 (8 patients): 20,000-49,000/mm3 (8 patients); 50,000-99,000/mm3 (10 patients). We conclude that the combination of thiotepa, 5FU, and leucovorin had significant myelotoxicity and do not recommend its routine use in the treatment of metastatic breast cancer.

Adult↗
PubMed1994

Dose-ranging study of recombinant human granulocyte-macrophage colony-stimulating factor in small-cell lung carcinoma.

PURPOSE: This randomized, multicenter, dose-finding study was undertaken to determine the dose of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) that can safely reduce neutropenia after cyclophosphamide, doxorubicin, and etoposide (CAVP-16) chemotherapy in patients with small-cell lung cancer (SCLC). Secondary clinical end points included incidence of infection, intravenous (IV) antimicrobial use, and chemotherapy delivered. PATIENTS AND METHODS: A total of 290 newly diagnosed SCLC patients were to receive six cycles of standard CAVP-16 chemotherapy on days 1 to 3 of every 21 days alone or with rhGM-CSF at 5, 10, or 20 micrograms/kg, administered subcutaneously (SC) on days 4 to 13 of each cycle. RESULTS: In cycle 1, median absolute neutrophil count (ANC) nadirs were twofold to threefold higher in patients who received rhGM-CSF, although all values were less than 500/microliters, and recovery from neutropenia was faster at all rhGM-CSF dosages versus observation (P < or = .01). In cycle 2, 56% of all patients given rhGM-CSF received full chemotherapy dosages (87.5% to 112.5% of projected dose) versus 36% of observation patients. During days 5 to 21 of cycle 1, fewer patients who received 10 micrograms/kg of rhGM-CSF required antibiotics compared with observation patients (11% v 29%, P < or = .01). Adverse events that occurred more frequently in rhGM-CSF-treated patients included injection-site reaction, edema, asthenia, paresthesia, diarrhea, myalgia, musculoskeletal pain, Pruritus, and rash (P < or = .10). Fever occurred more frequently in the 10- and 20-micrograms/kg rhGM-CSF groups than in the observation groups. The incidence in the 5-microgram/kg group was comparable to that in observation patients. Patients who received rhGM-CSF had a higher incidence of thrombocytopenia. CONCLUSION: rhGM-CSF at 5 to 10 micrograms/kg reduces chemotherapy-associated neutropenia and should be the dose range used in future studies.

Adult↗
PubMed1993

High-dose chlorambucil and dexamethasone for relapsed non-Hodgkin's lymphomas.

Twenty patients with relapsed or refractory non-Hodgkin's lymphoma were treated with high-dose chlorambucil (14 mg/m2 every 6 hours for 6 doses) and dexamethasone (40 mg/day for 5 days). There was a 45% response rate with 17% complete responses. The median duration of complete response was 7 months. The regimen was well tolerated and had minimal toxicity.

Adult↗
PubMed1992

Residual mediastinal mass after treatment of Hodgkin's disease: a decision analysis.

A residual mediastinal mass after completion of initial treatment for Hodgkin's disease is a frequent clinical problem. Investigators have suggested three possible approaches to this important problem: 1) observation, 2) additional diagnostic tests with subsequent action based upon test results, or 3) immediate treatment for high-risk patients. The method of decision analysis was applied to determine the optimal management for residual mediastinal abnormalities following treatment of Hodgkin's disease with combined modalities of MOPP chemotherapy and radiation therapy. The three parameters of the importance for making the best decision were: 1) the probability that the mass is truly active disease, 2) the salvage success rate using MOPP or ABVD treatment and 3) the specificity of the gallium scan. The analysis favored the gallium imaging strategy as an initial management choice when the probability was greater than 3% that the residual mass represented active disease and the specificity of gallium imaging was greater than 56%. This strategy proved to be the most cost effective, as well. Additional chemotherapy was favored only when there was a greater than 99% probability that the mass represented active disease. A nomogram has been constructed combining all three parameters of importance for graphically determining the best decision.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

GM-CSF in the treatment of Felty syndrome.

Many therapeutic agents have been tried with variable success in the treatment of Felty neutropenia, but the reports are anecdotal. We now describe the second trial of recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF), in a splenectomized, infected patient with Felty syndrome.

Felty Syndrome↗
PubMed1991

Dronabinol and prochlorperazine in combination for treatment of cancer chemotherapy-induced nausea and vomiting.

Dronabinol (Marinol, Roxane Laboratories, Columbus, OH) and prochlorperazine were tested alone and in combination in a randomized, double-blind, parallel group, multicenter study. Patients were randomized to receive either 1) dronabinol 10 mg every 6 hr plus placebo; 2) placebo plus prochlorperazine 10 mg every 6 hr; or 3) dronabinol and prochlorperazine, each 10 mg every 6 hr. Antiemetic treatment was begun 24 hr prior to and continued for 24 hr after the last dose of chemotherapy; all was given orally. Only 29% of patients in group 3 versus 47% in group 1 and 60% in group 2 experienced nausea after chemotherapy. In addition, the median duration per episode and severity of nausea were significantly less with combination therapy. Vomiting occurred after chemotherapy in 41%, 55%, and 35% of patients in groups 1, 2, and 3, respectively. The median duration per episode of vomiting was 1 min in group 3 versus two in group 1 and four in group 2. Side effects, primarily CNS, were more common in group 1 than in group 2; addition of prochlorperazine to dronabinol appeared to decrease the frequency of dysphoric effects seen with the latter agent. The combination was significantly more effective than was either single agent in controlling chemotherapy-induced nausea and vomiting.

Adult↗
PubMed1990

Monomethylated cap structures facilitate RNA export from the nucleus.

RNA export from the nucleus has been analyzed in Xenopus oocytes. U1 snRNAs made by RNA polymerase II were exported into the cytoplasm, while U1 snRNAs synthesized by RNA polymerase III, and therefore with a different cap structure, remained in the nucleus. Export of the polymerase II-transcribed RNAs was inhibited by the cap analog m7GpppG. Spliced mRNAs carrying monomethylguanosine cap structures were rapidly exported, while hypermethylated cap structures delayed mRNA export. The export of a mutant precursor mRNA unable to form detectable splicing complexes was also significantly delayed by incorporation of a hypermethylated cap structure. The results suggest that the m7GpppN cap structure is likely to be a signal for RNA export from the nucleus.

Animals↗
PubMed1990

The trimethylguanosine cap structure of U1 snRNA is a component of a bipartite nuclear targeting signal.

The ability of series of U1 snRNAs and U6 snRNAs to migrate into the nucleus of Xenopus oocytes after injection into the cytoplasm was analyzed. The U snRNAs were made either by injecting U snRNA genes into the nucleus of oocytes or, synthetically, by T7 RNA polymerase, incorporating a variety of cap structures. The results indicate that nuclear targeting of U1 snRNA requires both a trimethylguanosine cap structure and binding of at least one common U snRNP protein. Using synthetic U6 snRNAs, it is further demonstrated that the trimethylguanosine cap structure can act in nuclear targeting in the absence of the common U snRNP proteins. These results imply that U snRNP nuclear targeting signals are of a modular nature.

Animals↗
PubMed1990

Multiple domains of U1 snRNA, including U1 specific protein binding sites, are required for splicing.

Domains of U1 snRNA which are functionally important have been identified using a splicing complementation assay in Xenopus oocytes. Mutations in, and deletions of, all three of the hairpin loop structures near the 5' end of the RNA are strongly deleterious. Similarly, mutation of the Sm binding site abolishes complementation activity. Analysis of the protein binding properties of the mutant U1 snRNAs reveals that three of the functionally important domains, the first two hairpin loops and the Sm binding site, are required for interaction with U1 snRNP proteins. The fourth functionally important domain does not detectably affect snRNP protein binding and is not evolutionarily conserved. All of the deleterious mutations are shown to have similar effects on in vivo splicing complex formation.

Animals↗