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Hydroxyurea, a selective cytotoxic agent for cells in DNA synthesis, injected intraperitoneally at 24 and 48 hours after the first painting with 1 percent croton oil, significantly reduced the tumor yield in the two-stage chemical carcinlogenesis in mouse skin. A comparable group of mice receiving hydroxyurea only once at 24 hours had a tumor induction similar to that in controls.
Hydroxyurea-sensitive strains of Staphylococcus epidermidis and Micrococcus lysodeikticus showed marked thickening of cell walls and reduction in deoxyribonucleic acid synthesis when grown in the presence of hydroxyurea.
Hydroxyurea (5 x 10(-3) M) inhibits the development of vaccinia virus in HeLa cells early after infection and prevents the synthesis of viral deoxyribonucleic acid. In the presence of hydroxyurea, late viral polypeptides are not formed, as observed by electrophoresis on polyacrylamide gels.
Carbamoyloxyurea, an oxidation product of hydroxyurea, is bactericidal for Escherichia coli. Drug-induced killing is independent of cellular metabolism; ribonucleic acid and protein syntheses are the processes most affected, and the lethal action is accompanied by degradation of cellular deoxyribonucleic acid. In all of these effects the drug differs from hydroxyurea, a primarily bacteriostatic agent that inhibits deoxyribonucleic acid synthesis, whose lethal action ultimately depends on cellular activity.
Hydroxyurea inhibited synthesis of certain deoxyribonucleic acid (DNA) precursors and causes the cessation of DNA synthesis. It did not cause induction of lambda. Superinfection of an irradiated lysogen with lambdaind- could prevent induction, but the percentage of cells protected decreased as the time between irradiation and superinfection increased. The presence of hydroxyurea did not increase the time during which cells could be rescued by superinfection. The accumulation of DNA precursors after ultraviolet or ionizing radiation was not necessary for the induction of lambda prophage to occur.
The replication in Bacillus subtilis of the staphylococcal R plasmids pE194, pBD15, pUB110, pSA0501, and pSA2100 has been studied in the presence of hydroxyurea. In all cases, an enrichment for covalently closed circular DNA compared with chromosomal DNA was observed. In this respect, hydroxyurea mimics the effect previously observed with pUB110, using strains carrying the conditional mutation dnaA13. This mutation has been reported to affect ribonucleotide reductase (G. W. Bazill and D. Karamata, Mol. Gen. Genet. 117:19-29, 1972). An explanation for these effects is offered, together with some supporting evidence.
Forty-three patients with chronic myeloid leukaemia have been treated with hydroxyurea in order to be subjected to leucopheresis for white cell transfusions. Hydroxyurea decreases leucocytosis when it is administered and the blood granulocyte number increases soon after the drug is stopped. The survival of the patients is not different from the survival of the patients treated with conventional chemotherapy (busulphan, mitobronitol) and it is superior to the survival of patients treated with external radiotherapy or with (32)P. Half of the patients were subjected to splenectomy during first remission for a phase II trial. They were not randomized, but the distribution according to age was similar in the two groups. A slight difference appears in favour of splenectomy so far as survival is concerned, but there were three post-operative deaths out of 18 patients. We conclude that a phase II trial on the value of splenectomy is indicated ethically, but that the patients should be operated on and nursed in a microbiologically controlled environment.
We report on a patient with essential thrombocythemia treated with hydroxyurea who became febrile 3 weeks after the treatment was started. After drug withdrawal, the fever resolved but after rechallenge there was recurrence of the fever. Although hydroxyurea-induced fever is rare, this drug must be added to the list of drugs that produce fever and the physicians should be aware of this possibility.
A number of Pitymys duodecimcostatus males from a natural population were treated with hydroxyurea, which produces a gap in the spermatogenic line, to study the synaptic sequence of meiotic prophase. The use of substaging criteria, based on the morphological characteristics of the meiotic cells themselves, gave rise to a classification scheme consistent with the chronological sequence revealed by hydroxyurea treatment, which supports the usefulness of these independent criteria. The characteristics of meiotic prophase in P. duodecimcostatus are also described and discussed.
Epstein-Barr virus (EBV) DNA synthesis following EBV P3HR-1 superinfection of the Burkitt lymphoma cell line, Daudi, is refractory to mitomycin C and hydroxyurea at concentrations which inhibit cell DNA synthesis to greater than 98% of control values. Further, neither mitomycin C nor hydroxyurea inhibit virus antigen synthesis following P3HR-1 superinfection.
We describe the case of a 57-year-old woman with chronic myelogenous leukemia who was on hydroxyurea and developed a fatal thrombotic microangiopathy with renal, retinal and central nervous system involvement. There was no evidence of medullary or extramedullary leukemia transformation. Repeated examinations of the peripheral blood film revealed only minimal morphological changes of microangiopathic hemolysis. The diagnosis was made by postmortem examination of the kidneys, brain, meninges and retina. The underlying etiology may have been a paraneoplastic phenomenon of the chronic phase of CML or may have indicated the beginning of transformation to an accelerated phase. A late side effect of hydroxyurea therapy cannot be excluded.
Donor rats of the Hebrew University strain were administered a single intraperitoneal injection of hydroxyurea (400 mg/kg body weight). 1--3 h following the administration of the drug, a suspension of spleen cells, the majority of which consisted of lymphocytes, was prepared. Spleen cells were placed in diffusion chambers and these were implanted in the peritoneal cavity of preirradiated mice. 5--8 days following implantation, erythroid and granulocytic colonies developed in 30.3% of the diffusion chambers studied. However, in most chambers, macrophages were observed. In control experiments with implantation of spleen cells of normal rats, granulocytic colonies did not grow and in only 3.1% of the chambers erythroid colonies were noted. Macrophage colonies, however, developed in all 32 control cultures. Our previous studies showed that administration of a single dose of hydroxyurea strips the rat bone marrow of approximately 50% of replicating cells within 9--10 h. The results of the present study indicate that such a severe depletion of rat marrow cells results in early committment of spleen stem cells to various blood cell lines.
The initial presentation of acute leukemia as diffuse pulmonary infiltrates, especially with respiratory distress, is relatively infrequent and poses a therapeutic dilemma. Here we report a case of acute myeloid leukemia with diffuse pulmonary infiltration and respiratory distress symptom as the initial presentation that responded to hydroxyurea dramatically. This case demonstrates that hydroxyurea can be used effectively to decrease blast cell count and resolve leukemic infiltration of both lungs in patients with acute myeloblastic leukemia.
The in vitro effect of S-stage-specific drugs on the fetal hemoglobin (Hb F) potential of erythroid precursors and progenitors was tested by exposing bone marrow cells to 5-aza-2'-deoxycytidine, Ara-C, or hydroxyurea in suspension cultures and reculturing the cells in drug-free clonal cultures. Analysis of Hb F in the erythroblasts present at the end of suspension cultures and in the erythroid colonies formed from treated progenitors showed that 1 X 10(-9)-5 X 10(-8) M 5-aza-2'-deoxycytidine produced a concentration-related increase in the proportion of Hb F-positive erythroblasts, of Hb F-positive erythroid CFU (CFUe) colonies, and at the higher doses used, an increased Hb F expression in erythroid burst-forming unit (BFUe)-derived colonies. Preincubation of bone marrow cells with Ara-C produced significant megaloblastic changes by the end of the 2-d incubation and increased the proportion of Hb F-positive erythroblasts, CFUe colonies, and e-clusters, but BFUe-derived progeny was unaffected. Hydroxyurea failed to produce significant changes in Hb F at the range of concentrations used. The data raise the possibility of more than one mechanism underlying the stimulation of Hb F by S-stage drugs.
The unusual appearance of extensive skin ulcerations was observed in 17 patients with chronic myelogenous leukemia on continuous chemotherapy with hydroxyurea. The strict relationship between ulcers and therapy was proved by the complete (14 cases) or almost complete (3 cases) healing of lesions after therapy was discontinued. The possible pathogenetic mechanisms responsible for skin alterations are considered. The particular importance of the continuous hydroxyurea administration modality clearly emerges, suggesting the use of different administration modalities to reduce such serious side effects.
An 11-year-old boy with hemoglobin sickle disease (HbSD), bilateral stenosis of the intracranial carotid arteries, and moyamoya syndrome had recurrent ischemic strokes with aphasia and right hemiparesis. His parents (Jehovah's Witnesses) refused blood transfusions. After bilateral extracranial-intracranial (EC-IC) bypass surgery, hydroxyurea treatment increased hemoglobin F (HbF) levels to more than 30%. During a follow-up of 28 months, flow velocities in the basal cerebral arteries remained stable, neurologic sequelae regressed, and ischemic events did not recur. This is the first report of successful hydroxyurea treatment after bypass surgery for intracranial cerebral artery obstruction with moyamoya syndrome in sickle cell disease. The patient's religious background contributed to an ethically challenging therapeutic task. (Blood. 2001;97:2165-2167)
Targeted nucleotide exchange (TNE) is a process by which a synthetic DNA oligonucleotide, partially complementary to a site in a chromosomal or an episomal gene directs the reversal of a single nucleotide at a specific site. To protect against nuclease digestion, the oligonucleotide is modified with derivative linkages among the terminal bases. We have termed these molecules modified single-stranded oligonucleotides (MSOs). Current models suggest that the reaction occurs in two steps. The first, DNA pairing, involves the alignment of the MSO with the target site and its assimilation into the target helix forming a D-loop. The second phase centers around the repair of a single base mismatch formed between the MSO and its complementary strand in the D-loop. Nucleotide exchange is promoted in all likelihood by the mismatch repair system. A critical feature of successful TNE is the accessibility of the target site for the MSO and the factors that increase the dynamic nature of the chromatin that will likely increase the frequency. Here, we report that two factors, trichostatin A and hydroxyurea, elevate gene repair of a mutant hygromycin gene in Saccharomyces cerevisiae and a mutant eGFP gene in a mammalian cell line, MCF-10AT1 cells. Trichostatin A (TSA) acts by preventing the deacetylation of histones while hydroxyurea (HU) reduces the rate of replication. Both of these activities, by their very nature, create a more open configuration of the MSO into the target site.
PURPOSE: The paclitaxel, fluorouracil, and hydroxyurea regimen of paclitaxel, infusional fluorouracil, hydroxyurea, and twice-daily radiation therapy (TFHX) administered every other week has resulted in 3-year survival rates of 60% of stage IV patients. Locoregional and distant failure rates were 13% and 23%, respectively. To reduce distant failure rates, we added a brief course of induction chemotherapy to TFHX. PATIENTS AND METHODS: Sixty-nine patients received six weekly doses of carboplatin (AUC2) and paclitaxel (135 mg/m2) followed by five cycles of TFHX. RESULTS: Ninety-six percent had stage IV disease. Response to induction chemotherapy was partial response 52% and complete response (CR) 35%. Symptomatically, there was a significant reduction in mouth and throat pain. The most common grade 3 or 4 toxicity was neutropenia (36%). Best response following completion of TFHX was CR in 83%. Toxicities of TFHX consisted of grade 3 or 4 mucositis (74% and 2%) and dermatitis (47% and 14%). At a median follow-up of 28 months, locoregional or systemic disease progression were each noted in five patients. The overall 3-year progression-free survival was 80% (95% confidence interval [CI], 71% to 90%), and the 2- and 3-year overall survival rates were 77% (95% CI, 66% to 87%) and 70% (95% CI, 59% to 82%), respectively. At 12 months, five patients were completely feeding-tube dependent. CONCLUSION: Administration of carboplatin and paclitaxel before TFHX chemoradiotherapy results in high response activity and may decrease distant failure rates. Overall survival, progression, and organ preservation/functional outcome data support definitive evaluation of this approach.