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Biomedical subjects

A van Hoof

Publications and source records attributed to A van Hoof.

11 recordsLinked to original sources
PubMed2001

Itraconazole versus amphotericin B plus nystatin in the prophylaxis of fungal infections in neutropenic cancer patients.

The efficacy and safety of itraconazole oral solution and a combination of amphotericin B capsules plus nystatin oral suspension were compared in the prophylaxis of fungal infections in neutropenic patients. In an open, randomized, multicentre trial, 144 patients received itraconazole oral solution 100 mg bd, and 133 patients received amphotericin B 500 mg tds plus nystatin 2 MU qds. Overall, 65% of itraconazole-treated patients were considered to have had successful prophylaxis, compared with 53% in the polyene group. Proven deep fungal infections occurred in 5% of patients in each group. Fewer patients receiving itraconazole than amphotericin plus nystatin had superficial infections (3 versus 8%; P = 0.066). This trend in favour of itraconazole was seen in patients with profound neutropenia (neutrophil count <0.1 x 10(9) cells/L at least once) or prolonged neutropenia (neutrophil count <1.0 x 10(9) cells/L for >14 days). The median time to prophylactic failure was longer in the itraconazole group (37 days) than in the polyene group (34 days). The number of patients with fungal colonization (nose, sputum, stool) changed more favourably from baseline to endpoint in the itraconazole group than in the polyene group. Both treatments were safe and well tolerated; however, patients receiving amphotericin plus nystatin had a higher incidence of nausea and rash. In conclusion, itraconazole oral solution at doses of 100 mg bd and oral amphotericin B plus nystatin have similar prophylactic efficacy against fungal infections in neutropenic patients. On the basis of reduced incidence of superficial fungal infections, fungal colonization and specific adverse events, itraconazole may be the preferred treatment.

Adult↗
PubMed2000

Three conserved members of the RNase D family have unique and overlapping functions in the processing of 5S, 5.8S, U4, U5, RNase MRP and RNase P RNAs in yeast.

The biogenesis of a number of RNA species in eukaryotic cells requires 3' processing. To determine the enzymes responsible for these trimming events, we created yeast strains lacking specific 3' to 5' exonucleases. In this work, we describe the analysis of three members of the RNase D family of exonucleases (Rex1p, Rex2p and Rex3p). This work led to three important conclusions. First, each of these exonucleases is required for the processing of distinct RNAs. Specifically, Rex1p, Rex2p and Rex3p are required for 5S rRNA, U4 snRNA and MRP RNA trimming, respectively. Secondly, some 3' exonucleases are redundant with other exonucleases. Specifically, Rex1p and Rex2p function redundantly in 5.8S rRNA maturation, Rex1p, Rex2p and Rex3p are redundant for the processing of U5 snRNA and RNase P RNA, and Rex1p and the exonuclease Rrp6p have an unknown redundant essential function. Thirdly, the demonstration that the Rex proteins can affect reactions that have been attributed previously to the exosome complex indicates that an apparently simple processing step can be surprisingly complex with multiple exonucleases working sequentially in the same pathway.

Conserved Sequence↗
PubMed2000

Identification of BFN1, a bifunctional nuclease induced during leaf and stem senescence in Arabidopsis.

Nuclease I enzymes are responsible for the degradation of RNA and single-stranded DNA during several plant growth and developmental processes, including senescence. However, in the case of senescence the corresponding genes have not been reported. We describe the identification and characterization of BFN1 of Arabidopsis, and demonstrate that it is a senescence-associated nuclease I gene. BFN1 nuclease shows high similarity to the sequence of a barley nuclease induced during germination and a zinnia (Zinnia elegans) nuclease induced during xylogenesis. In transgenic plants overexpressing the BFN1 cDNA, a nuclease activity of about 38 kD was detected on both RNase and DNase activity gels. Levels of BFN1 mRNA were extremely low or undetectable in roots, leaves, and stems. In contrast, relatively high BFN1 mRNA levels were detected in flowers and during leaf and stem senescence. BFN1 nuclease activity was also induced during leaf and stem senescence. The strong response of the BFN1 gene to senescence indicated that it would be an excellent tool with which to study the mechanisms of senescence induction, as well as the role of the BFN1 enzyme in senescence using reverse genetic approaches in Arabidopsis.

Amino Acid Sequence↗
PubMed2000

Yeast exosome mutants accumulate 3'-extended polyadenylated forms of U4 small nuclear RNA and small nucleolar RNAs.

The exosome is a protein complex consisting of a variety of 3'-to-5' exonucleases that functions both in 3'-to-5' trimming of rRNA precursors and in 3'-to-5' degradation of mRNA. To determine additional exosome functions, we examined the processing of a variety of RNAs, including tRNAs, small nuclear RNAs (snRNAs), small nucleolar RNAs (snoRNAs), RNase P, RNase MRP, and SRP RNAs, and 5S rRNAs in mutants defective in either the core components of the exosome or in other proteins required for exosome function. These experiments led to three important conclusions. First, exosome mutants accumulate 3'-extended forms of the U4 snRNA and a wide variety of snoRNAs, including snoRNAs that are independently transcribed or intron derived. This finding suggests that the exosome functions in the 3' end processing of these species. Second, in exosome mutants, transcripts for U4 snRNA and independently transcribed snoRNAs accumulate as 3'-extended polyadenylated species, suggesting that the exosome is required to process these 3'-extended transcripts. Third, processing of 5.8S rRNA, snRNA, and snoRNA by the exosome is affected by mutations of the nuclear proteins Rrp6p and Mtr4p, whereas mRNA degradation by the exosome required Ski2p and was not affected by mutations in RRP6 or MTR4. This finding suggests that the cytoplasmic and nuclear forms of the exosome represent two functionally different complexes involved in distinct 3'-to-5' processing and degradation reactions.

DEAD-box RNA Helicases↗
PubMed2000

Function of the ski4p (Csl4p) and Ski7p proteins in 3'-to-5' degradation of mRNA.

One of two general pathways of mRNA decay in the yeast Saccharomyces cerevisiae occurs by deadenylation followed by 3'-to-5' degradation of the mRNA body. Previous results have shown that this degradation requires components of the exosome and the Ski2p, Ski3p, and Ski8p proteins, which were originally identified due to their superkiller phenotype. In this work, we demonstrate that deletion of the SKI7 gene, which encodes a putative GTPase, also causes a defect in 3'-to-5' degradation of mRNA. Deletion of SKI7, like deletion of SKI2, SKI3, or SKI8, does not affect various RNA-processing reactions of the exosome. In addition, we show that a mutation in the SKI4 gene also causes a defect in 3'-to-5' mRNA degradation. We show that the SKI4 gene is identical to the CSL4 gene, which encodes a core component of the exosome. Interestingly, the ski4-1 allele contains a point mutation resulting in a mutation in the putative RNA binding domain of the Csl4p protein. This point mutation strongly affects mRNA degradation without affecting exosome function in rRNA or snRNA processing, 5' externally transcribed spacer (ETS) degradation, or viability. In contrast, the csl4-1 allele of the same gene affects rRNA processing but not 3'-to-5' mRNA degradation. We identify csl4-1 as resulting from a partial-loss-of-function mutation in the promoter of the CSL4 gene. These data indicate that the distinct functions of the exosome can be separated genetically and suggest that the RNA binding domain of Csl4p may have a specific function in mRNA degradation.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Maintenance of remission with human recombinant interferon alfa-2a in patients with stages III and IV low-grade malignant non-Hodgkin's lymphoma. European Organization for Research and Treatment of Cancer Lymphoma Cooperative Group.

PURPOSE: Interferon alfa has shown significant activity in patients with low-grade malignant non-Hodgkin's lymphoma (NHL). In 1985, we initiated a prospective randomized study in which the potential benefit of interferon alfa given as maintenance treatment was investigated after tumor load reduction was achieved with chemoradiotherapy in patients with advanced low-grade malignant non-Hodgkin's lymphoma. PATIENTS AND METHODS: The study involved 347 patients with stage III or IV disease, 315 satisfying the eligibility criteria. All were treated with a regimen of cyclophosphamide, vincristine, and prednisone (CVP) given every 3 weeks for eight cycles. Thereafter, patients were eligible for iceberg irradiation. Finally, all patients were completely restaged, and responding and stable-disease patients were then randomized, 122 to interferon alfa-2a maintenance, 3 million U three times weekly for 1 year; and 120 to no further treatment. RESULTS: Seventy-nine percent of the patients response to CVP, ie, 45% complete remissions (CR) and 34% partial remissions (PR). In the group of randomized patients, the response rate after CVP plus or minus radiotherapy was 90%. As compared with control patients, patients in the interferon (IFN) maintenance group had a tendency toward a prolonged time to progression (TTP) (median, 132 v 87 weeks; P = .054, adjusted for response to CVP). However, overall survival was similar in both groups. Interferon was well tolerated. The median dose of IFN actually received corresponded to 90% of the planned cumulative dose. The treatment had to be stopped because of toxicity in 16 patients (15% of the patients in whom IFN was started). CONCLUSION: Interferon maintenance treatment in the phase of minimal residual disease of patients with advanced low-grade malignant NHL increased TTP at the borderline of statistical significance, without remarkable toxicity. However, overall survival was not influenced.

Adult↗
PubMed1997

Rare codons are not sufficient to destabilize a reporter gene transcript in tobacco.

In plants, as in other eukaryotes, most synonymous codons of the genetic-code are not used with equal frequency, but instead some codons are preferred, whereas others are rare. Circumstantial evidence led to the suggestion that rare codons have a negative influence on mRNA stability. To address this question experimentally, rare codons encoded by a Bacillus thuringiensis (B.t.) toxin gene (cryIA(c)) or a synthetic sequence were introduced into a phytohemagglutinin (PHA) reporter gene. In neither case was the mRNA stability appreciably diminished in stably transformed tobacco cell cultures nor was the accumulation of mRNA in transgenic plants affected. Thus rare codons do not appear to be sufficient to cause rapid degradation of the PHA mRNA and potentially other mRNAs in plants.

Cell Line↗
PubMed1997

Patients with stage III/IV Hodgkin's disease in partial remission after MOPP/ABV chemotherapy have excellent prognosis after additional involved-field radiotherapy: interim results from the ongoing EORTC-LCG and GPMC phase III trial. The EORTC Lymphoma Cooperative Group and Groupe Pierre-et-Marie-Curie.

BACKGROUND: Failure to reach complete remission (CR) with chemotherapy in advanced stages of Hodgkin's disease is considered a poor prognostic factor for progression-free and overall survival. The role of radiotherapy after chemotherapy-induced remission is controversial. PATIENTS AND METHODS: In 1989, the EORTC/GPMC started a randomized phase III trial on involved-field RT (IF-RT) after MOPP/ABV hybrid-induced remission in patients with stage III/IV Hodgkin's disease. In this ongoing trial, patients in CR after chemotherapy are randomized between IF-RT and no further treatment. Patients in partial remission (PR) all receive IF-RT. Patients, age 15-70 years, with previously untreated stage III/IV Hodgkin's disease are eligible. The randomized treatment arms are still blinded. The interim analysis of May 1996 focuses on the outcome of patients in chemotherapy-induced PR. RESULTS: A total of 405 of 493 registered patients were evaluable for response to chemotherapy. Fifty-nine percent of patients attained a CR, 37% a PR, and only 4% failed to respond. The IF-RT was actually given to 90% of the PR patients. After a median follow-up of 43 months, the five year progression-free and overall survival for patients in PR was 75% and 87%, respectively. CONCLUSION: IF-RT after MOPP/ABV-induced partial remission in stage III/IV Hodgkin's disease produces excellent failure-free and overall survival. Early intensification of treatment of this group of patients is not indicated.

Adult↗
PubMed1996

Premature nonsense codons decrease the stability of phytohemagglutinin mRNA in a position-dependent manner.

Premature termination of translation has often been associated with decreased mRNA accumulation in plants, but the affected step in gene expression has not been identified. To investigate this problem, the expression of wild-type and mutant alleles of the bean phytohemagglutinin (PHA) gene has been examined in tobacco cells and transgenic plants. Measurement of mRNA decay rates in stably transformed cell lines demonstrated that premature nonsense codons markedly destabilized the mRNA. This decreased stability was also reflected by decreased accumulation of transcripts containing premature nonsense codons in transgenic plants. The positional dependence of the nonsense codon effect was evaluated by introducing premature nonsense codons at different distances from the PHA AUG start codon. Transcripts with nonsense codons about 20, 40 or 60% of the way through the normal PHA coding region yielded highly unstable mRNAs, whereas a transcript with a nonsense codon at 80% was as stable as wild-type. The ability to recognize and rapidly degrade certain transcripts with early nonsense codons could provide plant cells with a means to minimize the production of wasteful and possible deleterious truncated proteins.

Alleles↗
PubMed1995

Recombinant human erythropoietin in the anemia associated with multiple myeloma or non-Hodgkin's lymphoma: dose finding and identification of predictors of response.

Previous phase I-II clinical trials have shown that recombinant human erythropoietin (rHuEpo) can ameliorate anemia in a portion of patients with multiple myeloma (MM) and non-Hodgkin's lymphoma (NHL). Therefore, we performed a randomized controlled multicenter study to define the optimal initial dosage and to identify predictors of response to rHuEpo. A total of 146 patients who had hemoglobin (Hb) levels < or = 11 g/dL and who had no need for transfusion at the time of enrollment entered this trial. Patients were randomized to receive 1,000 U (n = 31), 2,000 U (n = 29), 5,000 U (n = 31), or 10,000 U (n = 26) of rHuEpo daily subcutaneously for 8 weeks or to receive no therapy (n = 29). Of the patients, 84 suffered from MM and 62 from low- to intermediate-grade NHL, including chronic lymphocytic leukemia; 116 of 146 (79%) received chemotherapy during the study. The mean baseline Hb level was 9.4 +/- 1.0 g/dL. The median serum Epo level was 32 mU/mL, and endogenous Epo production was found to be defective in 77% of the patients, as judged by a value for the ratio of observed-to-predicted serum Epo levels (O/P ratio) of < or = 0.9. An intention-to-treat analysis was performed to evaluate treatment efficacy. The median average increase in Hb levels per week was 0.04 g/dL in the control group and -0.04 (P = .57), 0.22 (P = .05), 0.43 (P = .01), and 0.58 (P = .0001) g/dL in the 1,000 U, 2,000 U, 5,000 U, and 10,000 U groups, respectively (P values versus control). The probability of response (delta Hb > or = 2 g/dL) increased steadily and, after 8 weeks, reached 31% (2,000 U), 61% (5,000 U), and 62% (10,000 U), respectively. Regression analysis using Cox's proportional hazard model and classification and regression tree analysis showed that serum Epo levels and the O/P ratio were the most important factors predicting response in patients receiving 5,000 or 10,000 U. Approximately three quarters of patients presenting with Epo levels inappropriately low for the degree of anemia responded to rHuEpo, whereas only one quarter of those with adequate Epo levels did so. Classification and regression tree analysis also showed that doses of 2,000 U daily were effective in patients with an average platelet count greater than 150 x 10(9)/L. About 50% of these patients are expected to respond to rHuEpo. Thus, rHuEpo was safe and effective in ameliorating the anemia of MM and NHL patients who showed defective endogenous Epo production. From a practical point of view, we conclude that the decision to use rHuEpo in an individual anemic patient with MM or NHL should be based on serum Epo levels, whereas the choice of the initial dosage should be based on residual marrow function.

Adult↗