Arthur S. Levine

Recruitment of p300/CBP in p53-Dependent Signal Pathways

The products of the p53 and CBP/p300 genes have been individually implicated in control of cell growth and regulation of transcription. p53 is known to act as a positive and negative regulator of gene expression. Here we show that p53, in both wild-type and mutant conformation, forms a specific protein complex with p300. However, in its wild-type but not mutant conformation, p53 inhibits a promoter containing the DNA-binding sequences for the transcription factor AP1, in a p300-dependent manner. p300 stimulates the transcriptional activity of p53 on p53-regulated promoters, and it enhances the responsiveness to a physiological upstream modulator of p53 function, ionizing radiation. A dominant negative form of p300 prevents transcriptional activation by p53, and it counteracts p53-mediated G1 arrest and apoptosis. The data implicate p300 as an important component of p53-signaling, thus providing new insight into the mechanisms of cellular proliferation.

Duration of empiric antibiotic therapy in granulocytopenic patients with cancer

Abstract Early initiation of empiric antibiotic therapy in febrile cancer patients has become established practice, but the appropriate duration of antibiotic therapy when no infectious source can be identified is unknown. The complications of broad-spectrum antibiotics argue for brief treatment, but the risk of an inadequately treated infection in the granulocytopenic patient favors longer therapy. We prospectively studied 306 episodes of fever and granulocytopenia in 143 patients with leukemia or solid tumor (age one to 33 years) with respect to the duration of empiric antibiotic treatment. Eligible patients (fever > 38 °C three times/24 hours or > 38.5 °C once, plus polymorphonuclear leukocytes 3 ) had an extensive diagnostic evaluation, including at least two preantibiotic blood cultures, and therapy was then started with a broad-spectrum antibiotic regimen— Keflin ® , gentamicin and carbenicillin (KGC). Initial evaluation failed to identify an infectious etiology for the fever in 142 of 306 (46 per cent) episodes. Fifty-six of 142 (39 per cent) of these fevers of unknown origin were associated with persistent granulocytopenia for more than seven days; in 33 of these, defervescence occurred while the patients received KGC. After seven days of empiric KGC therapy, the 33 patients with fevers of unknown origin who had become afebrile with empiric antibiotics but whose polymorphonuclear leukocytes remained less than 500/mm 3 were randomized to either continue or discontinue (dc) to receive KGC. The patients who continued to receive KGC until their polymorphonuclear leukocytes were more than 500/mm 3 had no infectious sequelae. However, in seven of 17 (41 per cent) of the patients randomized to dc KGC infectious sequelae developed (p = 0.007) within a median of two days of discontinuing KGC (two with fever which again responded to KGC therapy, and five with a documented infection [two ultimately fatal]). In none of the patients did a resistant microbial flora or superinfection develop. These data suggest that the patient with a fever of unknown origin who becomes afebrile during empiric antibiotic therapy may profit from continued therapy while granulocytopenia persists.

Prolonged complete remission following high dose chemotherapy of burkitt's lymphoma in relapse

Fourteen patients with American Burkitts lymphoma resistant to conventional chemotherapy were treated with high‐dose combination chemotherapy and intensive supportive care. Four patients died shortly after chemotherapy, 3 of an acute carditis. All ten remaining patients demonstrated tumor regression and 3 remain in prolonged complete unmaintained remission 29+, 19+, and 9+ months after treatment. These findings demonstrate that high‐dose chemotherapy will benefit some patients with Burkitts lymphoma unresponsive to conventional chemotherapy, but the medullary and extramedullary toxicity of this treatment strategy remains a formidable obstacle.

Lack of Clinical Usefulness of the Limulus Test in the Diagnosis of Endotoxemia

Studies of the clinical value of the limulus amebocyte lysate test for the detection of endotoxemia are inconsistent. In an attempt to define the value of this test, a total of 237 plasma samples from 111 patients were tested for endotoxin with seven different lysate preparations. A total of 48 plasma samples yielded a positive test with one or more of the seven preparations. Two of eight samples positive with all seven preparations were from ambulatory patients. A significant positive correlation of the test with bacteremia, neutrophilia and elevated serum alkaline phosphatase was found. Only three of the 48 positive tests occurred by four hours of incubation, and only 12 were associated with positive blood cultures (eight contained gram-negative bacteria). The test now available has no clinical usefulness in the detection of endotoxemia or gram-negative septicemia.

USE OF A PSEUDOMONAS AERUGINOSA VACCINE IN PATIENTS WITH ACUTE LEUKEMIA AND CYSTIC FIBROSIS

A heptavalent lipopolysaccharide Pseudomonas vaccine was evaluated in 22 patients with acute leukemia and 12 patients with cystic fibrosis during an 18 month interval at the Clinical Center of the National Institutes of Health. Of the 34 patients, 32 had an excellent serum hemagglutinating (HA) antibody response to immunization. In comparison to the patients with cystic fibrosis, the patients with leukemia had a smaller HA antibody response, which lasted a shorter period of time, and also experienced greater toxicity from the vaccine. The mixing of adrenal corticosteroids with vaccine greatly decreased side reactions among the patients with leukemia without significantly inhibiting antibody production. Previous antineoplastic chemotherapy had little influence on antibody response in patients with leukemia, with the exception of methortrexate. Vaccinated patients with leukemia had 1 Pseudomonas infection of 14 bacterial or fungal infections, whereas 2 pseudomonas infections of 5 bacterial or fungal infections occurred in a control group of 20 patients with acute leukemia. Of the 12 patients with cystic fibrosis, 4 had a Pseudomonas infection after vaccination.

Relationship of the xeroderma pigmentosum group E DNA repair defect to the chromatin and DNA binding proteins UV-DDB and replication protein A

ABSTRACT Cells from complementation groups A through G of the heritable sun-sensitive disorder xeroderma pigmentosum (XP) show defects in nucleotide excision repair of damaged DNA. Proteins representing groups A, B, C, D, F, and G are subunits of the core recognition and incision machinery of repair. XP group E (XP-E) is the mildest form of the disorder, and cells generally show about 50% of the normal repair level. We investigated two protein factors previously implicated in the XP-E defect, UV-damaged DNA binding protein (UV-DDB) and replication protein A (RPA). Three newly identified XP-E cell lines (XP23PV, XP25PV, and a line formerly classified as an XP variant) were defective in UV-DDB binding activity but had levels of RPA in the normal range. The XP-E cell extracts did not display a significant nucleotide excision repair defect in vitro, with either UV-irradiated DNA or a uniquely placed cisplatin lesion used as a substrate. Purified UV-DDB protein did not stimulate repair of naked DNA by DDB− XP-E cell extracts, but microinjection of the protein into DDB−XP-E cells could partially correct the repair defect. RPA stimulated repair in normal, XP-E, or complemented extracts from other XP groups, and so the effect of RPA was not specific for XP-E cell extracts. These data strengthen the connection between XP-E and UV-DDB. Coupled with previous results, the findings suggest that UV-DDB has a role in the repair of DNA in chromatin.

Sepsis with a New Species of Corynebacterium

Sepsis with a previously undescribed species of Corynebacterium was documented in four patients. All patients had predisposing illness at the time of infection, three patients having leukemia in relapse and one having a porencephalic cyst and a ventriculoatrial shunt. The isolates from blood cultures had a characteristic metallic sheen when grown on blood agar. They were resistant to most antibiotics tested, including the penicillins, but were uniformly sensitive to vancomycin. Common biochemical characteristics, the metallic sheen, and the unusual antibiotic sensitivity pattern suggest that these isolates comprise a new species or group of closely related species of Corynebacterium that is capable of infection in man.

Oncogene alterations in primary, recurrent, and metastatic human bone tumors.

We investigated the structure and the expression of various oncogenes in three of the most common human bone tumors—osteosarcoma (36 samples from 34 patients), giant cell tumor (10 patients), and chondrosarcoma (18 patients)—in an attempt to identify the genetic alterations associated with these malignancies. Alterations of RB and p53 were detected only in osteosarcomas. Alterations of c‐myc, N‐myc, and c‐fos were detected in osteosarcomas and giant cell tumors. Ras alterations (H‐ras, Ki‐ras, N‐ras) were rare. Chondrosarcomas did not contain any detectable genetic alterations. Our results suggest that alterations of c‐myc, N‐myc, and c‐fos oncogenes occur in osteosarcomas, in addition to those previously described for the tumor suppressor genes RB and p53. Moreover, statistical analyses indicate that c‐fos alterations occur more frequently in osteosarcoma patients with recurrent or metastatic disease.

Pseudomonas aeruginosa Infections: Persisting Problems and Current Research to Find New Therapies

Despite the availability of specific antibiotics, Pseudomonas aeruginosa bacteria still cause troublesome infections in patients with a variety of illnesses: extensive thermal injury, leukopenia from antineoplastic chemotherapy and other forms of immunosuppressive treatment, chronic pulmonary disease such as cystic fibrosis, or intravenous narcotic use. The use of antibiotics has improved the prognosis of pseudomonas infections considerably. However, patients with marginal or defective host immunity may need more extensive therapy to master the infection. By evaluating additional modalities of treatment such as granulocyte replacement, improved usage of antibiotics, and active (prophylaxis) or passive antibody administration, the optimal combination may be found.

The Cullin 4B-Based UV-Damaged DNA-Binding Protein Ligase Binds to UV-Damaged Chromatin and Ubiquitinates Histone H2A

By removing UV-induced lesions from DNA, the nucleotide excision repair (NER) pathway preserves the integrity of the genome. The UV-damaged DNA-binding (UV-DDB) protein complex is involved in the recognition of chromatin-embedded UV-damaged DNA, which is the least understood step of NER. UV-DDB consists of DDB1 and DDB2, and it is a component of the cullin 4A (CUL4A)-based ubiquitin ligase, DDB1-CUL4A(DDB2). We previously showed that DDB1-CUL4A(DDB2) ubiquitinates histone H2A at the sites of UV lesions in a DDB2-dependent manner. Mutations in DDB2 cause a cancer prone syndrome, xeroderma pigmentosum group E (XP-E). CUL4A and its paralog, cullin 4B (CUL4B), copurify with the UV-DDB complex, but it is unclear whether CUL4B has a role in NER as a separate E3 ubiquitin ligase. Here, we present evidence that CUL4A and CUL4B form two individual E3 ligases, DDB1-CUL4A(DDB2) and DDB1-CUL4B(DDB2). To investigate CUL4Bs possible role in NER, we examined its subcellular localization in unirradiated and irradiated cells. CUL4B colocalizes with DDB2 at UV-damaged DNA sites. Furthermore, CUL4B binds to UV-damaged chromatin as a part of the DDB1-CUL4B(DDB2) E3 ligase in the presence of functional DDB2. In contrast to CUL4A, CUL4B is localized in the nucleus and facilitates the transfer of DDB1 into the nucleus independently of DDB2. Importantly, DDB1-CUL4B(DDB2) is more efficient than DDB1-CUL4A(DDB2) in monoubiquitinating histone H2A in vitro. Overall, this study suggests that DDB1-CUL4B(DDB2) E3 ligase may have a distinctive function in modifying the chromatin structure at the site of UV lesions to promote efficient NER.