Replication protein A interactions with DNA. 2. Characterization of double-stranded DNA-binding/helix-destabilization activities and the role of the zinc-finger domain in DNA interactions

Human replication protein A (RPA) is a heterotrimeric single-stranded DNA-binding protein that is composed of subunits of 70, 32, and 14 kDa. RPA is required for multiple processes in cellular DNA metabolism. RPA has been reported to (1) bind with high affinity to single-stranded DNA (ssDNA), (2) bind specifically to certain double-stranded DNA (dsDNA) sequences, and (3) have DNA helix-destabilizing ("unwinding") activity. We have characterized both dsDNA binding and helix destabilization. The affinity of RPA for dsDNA was lower than that of ssDNA and precisely correlated with the melting temperature of the DNA fragment. The rates of helix destabilization and dsDNA binding were similar, and both were slow relative to the rate of binding ssDNA. We have previously mapped the regions required for ssDNA binding [Walther et al. (1999) Biochemistry 38, 3963-3973]. Here, we show that both helix-destabilization and dsDNA-binding activities map to the central DNA-binding domain of the 70-kDa subunit and that other domains of RPA are needed for optimal activity. We conclude that all types of RPA binding are manifestations of RPA ssDNA-binding activity and that dsDNA binding occurs when RPA destabilizes a region of dsDNA and binds to the resulting ssDNA. The 70-kDa subunit of all RPA homologues contains a highly conserved putative (C-X2-C-X13-C-X2-C) zinc finger. This motif directly interacts with DNA and contributes to dsDNA-binding/unwinding activity. Evidence is presented that a metal ion is required for the function of the zinc-finger motif.

Replication protein A interactions with DNA. 1. Functions of the DNA-binding and zinc-finger domains of the 70-kDa subunit

Human replication protein A (RPA) is a multiple subunit single-stranded DNA-binding protein that is required for multiple processes in cellular DNA metabolism. This complex, composed of subunits of 70, 32, and 14 kDa, binds to single-stranded DNA (ssDNA) with high affinity and participates in multiple protein-protein interactions. The 70-kDa subunit of RPA is known to be composed of multiple domains: an N-terminal domain that participates in protein interactions, a central DNA-binding domain (composed of two copies of a ssDNA-binding motif), a putative (C-X2-C-X13-C-X2-C) zinc finger, and a C-terminal intersubunit interaction domain. A series of mutant forms of RPA were used to elucidate the roles of these domains in RPA function. The central DNA-binding domain was necessary and sufficient for interactions with ssDNA; however, adjacent sequences, including the zinc-finger domain and part of the N-terminal domain, were needed for optimal ssDNA-binding activity. The role of aromatic residues in RPA-DNA interactions was examined. Mutation of any one of the four aromatic residues shown to interact with ssDNA had minimal effects on RPA activity, indicating that individually these residues are not critical for RPA activity. Mutation of the zinc-finger domain altered the structure of the RPA complex, reduced ssDNA-binding activity, and eliminated activity in DNA replication.

Adenoid cystic carcinoma of the maxillary antrum

PURPOSE

To investigate characteristic clinical features and outcome for patients with adenoid cystic carcinoma (ACC) of the maxillary antrum.

PATIENTS AND METHODS

Twenty-two patients with ACC of the maxillary antrum were initially treated with surgery alone (3 patients), radiation alone (9 patients), or a combination of surgery and radiation (10 patients). Salvage treatment for initial failure was individualized. Patterns of failure, survival, and prognostic factors were retrospectively analyzed.

RESULTS

The most frequent site of failure was local recurrence at the primary site (72.7%). All patients treated with either surgery alone or radiation alone experienced one or more local recurrences, whereas patients who received planned combined surgery and radiation had a much lower local recurrence rate (40%). Neck node failure (4.6%) was an uncommon event, whereas distant metastases were clinically documented in seven patients (32%). Most of the treatment failures appeared within 5 years, but treatment failures after 5 years were not uncommon. The overall survival and disease-free survival rates at 10 years were 37.6% and 13.6%, respectively. Clinicopathological factors, such as location of primary tumor, tumor stage, and histological grade were of no value in predicting a favorable survival. The significant prognostic factors influencing 10-year survival were the pathological finding of perineural invasion and the initial mode of treatment.

CONCLUSION

ACC of the maxillary antrum represented a unique natural history characterized by a more aggressive tumor behavior and an unfavorable prognosis. Combined surgery and radiotherapy is recommended for optimal local control and survival.

Cloning and characterization of a cell surface receptor for xenotropic and polytropic murine leukemia viruses

Xenotropic and polytropic murine leukemia viruses (X-MLVs and P-MLVs) cross-interfere to various extents in non-mouse species and in wild Asian mice, suggesting that they might use a common receptor for infection. Consistent with this hypothesis, the susceptibility of some wild mice to X-MLVs has been mapped to the P-MLV receptor locus at the distal end of mouse chromosome 1. In this study, we report the isolation and characterization of a cDNA for the human X-MLV cell surface receptor (X-receptor) by using a human T lymphocyte cDNA library in a retroviral vector. The predicted X-receptor contains 696 amino acids with multiple hydrophobic potential membrane-spanning sequences and with weak homologies to the yeast proteins SYG1, of unknown function, and PHO81, which has been implicated in a system that regulates transport of inorganic phosphate. Expression of the X-receptor in Chinese hamster ovary cells, which are substantially resistant to P-MLVs and to X-MLVs, made them susceptible to both of these virus groups. The mouse homologue of the X-receptor was mapped by hybridization to the distal end of chromosome 1 at the same position as the P-MLV receptor gene Rmc1. These results strongly support the hypothesis that a common gene encodes the receptors for X-MLVs and P-MLVs, with the human X-receptor preferentially mediating X-MLV infections and the homologous protein of inbred mice mediating only P-MLV infections. We propose that X-MLVs and P-MLVs comprise a single family of retroviruses that have coevolved in response to diversification in X-receptor genes of the host.

The human RNA helicase A (DDX9) gene maps to the prostate cancer susceptibility locus at chromosome band 1q25 and its pseudogene (DDX9P) to 13q22, respectively

RNA helicase A is the homolog of the Drosophila maleless protein, an essential factor involved in dosage compensation, and plays a crucial role in early development in mammals. Here, we have mapped the human RNA helicase A (DDX9) gene to the major susceptibility locus for prostate cancer at chromosome band 1q25, and its pseudogene (DDX9P) to the band 13q22 by fluorescence in situ hybridization, somatic cell hybrid analysis, and assignment of YAC clones, respectively.

Limb reduction defects in endothelial nitric oxide synthase-deficient mice

Nitric oxide synthases are a family of enzymes capable of converting L-arginine to L-citrulline with the subsequent release of nitric oxide (NO). NO has been shown to have multiple biologic effects depending on the isoform responsible for its production and its tissue of origin. Murine endothelial nitric oxide synthase (eNOS) is encoded by Nos3, located on mouse chromosome 5. NO produced from this isoform causes vascular smooth muscle relaxation. Other investigators have shown that the administration of nonspecific inhibitors of nitric oxide synthases to pregnant rats induces limb reduction defects. However, mice deficient in Nos3 have not previously been noted to show such abnormalities. To explore the importance of eNOS during development, we produced mice deficient in eNOS using embryonic stem cell technology. Limb reduction defects were seen in approximately 10% of the null animals. We also observed increased neonatal loss of homozygous deficient pups. One functional copy of Nos3 eliminates the risk of limb defects observed in our mouse strain. These findings have implications for understanding genetic predisposition to sporadic limb reduction defects in humans.

Target specificity of immunoglobulin class switch recombination is not determined by nucleotide sequences of S regions

We describe a model system for class switch recombination (CSR) using CH12F3-2 cells transfected with a DNA construct containing two S sequences transcribed by different promoters and separated by a viral thymidine kinase (TK) gene. Recombination observed using this system shares key properties with physiological CSR: deletion of DNA between two S regions, requirement for cytokine stimulation, and nonhomologous and no consensus breakpoint sequences. Studies on transfectants with variants of this construct led us to the following conclusions: (1) two S sequences are required for CSR; (2) isotype specificity of recombination is not determined by nucleotide sequences of S regions; (3) S sequences are not strand-specific; and (4) induction of recombination activity requires cytokine stimulation.

Combination of bupivacaine scalp circuit infiltration with general anesthesia to control the hemodynamic response in craniotomy patients

BACKGROUND

Sudden and overwhelming increases in blood pressure (BP) and heart rate (HR) during incision of the scalp may give rise to morbidity or mortality in patients with intracranial pathology undergoing neurosurgery. A modification of the method proposed by Labat to abate this circumstantiality was applied in a group of patients receiving craniotomy. The modified method was to combine scalp circuit infiltration of local anesthetic with general anesthesia to control the hemodynamic response to craniotomy.

METHODS

Twenty-six patients scheduled to undergo craniotomy were randomly divided into two groups. Patients whose conditions or their current medication that might affect the stability of hemodynamics were excluded. In group A patients (N = 16) 25-30 ml of 0.25% bupivacaine was used for scalp circuit infiltration on the operation side, while in those of group B (N = 10) the same volume of 0.9% normal saline was used. After induction, anesthesia was maintained with 0.6% to 1.2% end-tidal isoflurane (ET-Iso) and 50% N2O in oxygen (N2O:O2 = 2 l/min:2 l/min). The end-tidal CO2 was kept within the range of 25-30 mmHg. BP and HR were recorded every five min before incision and then every two min after incision until one hour after induction. ET-Iso was also recorded every two min throughout a period of sixty min. If the BP and HR increased above 20% of the baseline (10 min before incision), thiopental 2.5 mg/kg and fentanyl 2 micrograms/kg were administered. If hypertension became sustained, the isoflurane concentration was adjusted until an acceptable level was obtained.

RESULTS

The mean BP during the surgery was 92 +/- 1 mmHg in group A and 92 +/- 7 mmHg in group B. The difference in BP between incision to 6 min after incision was statistically significant (P < 0.05). The mean HR during surgery was 101 +/- 5 beats/min in group B and 91 +/- 2 beats/min in group A, the difference of which was not statistically significant. All of the patients in group B required a deepened anesthesia to keep the BP and HR within the normal range, but no patient in group A had such need. The average concentration of ET-Iso during the 60 min period was 0.95 +/- 0.12% in group B and 0.41 +/- 0.01% in group A, respectively. The difference was statistically significant (P < 0.05).

CONCLUSIONS

Our results showed that scalp circuit infiltration with 0.25% bupivacaine significantly improved the cardiovascular stability and reduced the requirement of isoflurane during craniotomy. The routine use of bupivacaine scalp circuit infiltration in patients undergoing craniotomy should be considered.

RNA helicase A is essential for normal gastrulation

RNA helicase A (RHA) is the human homologue of the Drosophila maleless protein, an essential factor for the development of male flies. Recently, it was shown that RHA cooperates with the cAMP-responsive element in mediating the cAMP-dependent transcriptional activation of a number of genes. Due to the participation of cAMP as a second messenger in a number of signaling pathways, we examined the function of RHA during mammalian embryogenesis. To examine the role(s) of RHA in mammalian development, RHA knockout mice were generated by homologous recombination. Homozygosity for the mutant RHA allele led to early embryonic lethality. Histological analysis, combined with terminal deoxynucleotidyltransferase-mediated UTP end labeling (TUNEL) reactions of RHA-null embryos, revealed marked apoptotic cell death specifically in embryonic ectodermal cells during gastrulation. RNA in situ analyses of the expression of HNF-3beta and Brachyury, two molecular markers for gastrulation, showed that RHA-null embryos at days 7.5 and 8.5 expressed both HNF-3beta and Brachyury in a pattern similar to those of pre- and early streak stages of embryos, respectively. These observations indicate that RHA is necessary for early embryonic development and suggest the requirement of RHA for the survival and differentiation of embryonic ectoderm.

Differences in gross target volumes on contrast vs. noncontrast CT scans utilized for conformal radiation therapy treatment planning for prostate carcinoma

PURPOSE

To compare the gross target volumes (GTVs) (prostate and seminal vesicles) defined on noncontrast and contrast-enhanced computed tomography (CT) images used for three-dimensional conformal treatment planning (3DCRT).

METHODS AND MATERIALS

From 1993 to 1996, 39 patients referred for radiation therapy for adenocarcinoma of the prostate underwent pretreatment pelvic CT scanning with and without intravenous (i.v.) contrast for treatment planning purposes. Seven patients were excluded because of incomplete data sets. The prostate and seminal vesicles were outlined by the same physician on all images of 32 patients. On 18 CT exams, the prostate and seminal vesicles were blindly outlined a second time by the same physician to evaluate intraphysician consistency. Discrepancies between the GTVs outlined with and without contrast and between the first and second outline on the same study were assessed by calculating the projected area in the anterior-to-posterior (AP) and right lateral (RLAT) beam's-eye view (BEV). To assess the magnitude, frequency, and direction of discrepancies between the two GTVs, the extension of the GTVs in six directions (right, left, anterior, posterior, cephalad, and caudal) was determined.

RESULTS

The GTV outlined with contrast was larger in all directions, except caudal, in the majority of patients. The change in the GTV with contrast was significant in the cephalad (p=0.0003) and right (p=0.0007) directions, but not in the other directions. Although the increase with contrast in any direction was usually small (average < or =5 mm), these changes resulted in a significant increase in GTV area in both the AP and RLAT BEV (9.0%, p=0.0017 and 8.2%, p=0.023, respectively). The intraphysician variability in outlining the prostate/ seminal vesicles was minimal.

CONCLUSIONS

The addition of i.v. contrast does appear to make a significant difference in how the prostate and seminal vesicles are outlined by an experienced observer. The increase in area of the target, found when contrast is used, should be taken into consideration when designing the treatment fields for patients with carcinoma of the prostate.

Detection of Cryptosporidium oocysts in canine fecal samples by immunofluorescence assay

Fecal samples were collected from 257 dogs in four areas in Korea during the period of January 1996 to November 1997 and examined by immunofluorescence assay for Cryptosporidium oocysts using a commercial diagnostic kit (Meridian Diagnostics, Cincinnati, Ohio). Of the 257 samples, 25 (9.7%) were positive for Cryptosporidium. Differences were noted in the prevalence of canine cryptosporidiosis in both areas and dog types. The results provide a further evidence of environmental contamination and widespread distribution of the parasite in Korea.

Detection of MYC gene amplification in malignant lymphomas

The role of oncogene or tumor supressor gene in Epstein-Barr virus (EBV) associated malignant lymphomas (MLs) is poorly understood. We examined 36 MLs (21 EBV positive and 15 EBV negative) and 6 reactive hyperplasias for the presence of myc gene amplification. Polymerase chain reaction (PCR) technology was used to examine the state of amplification of the proto-oncogene c-myc in formalin-fixed paraffin-embedded tissues. Variable degrees of myc gene amplification were detected in reactive hyperplasias and MLs. However, significant increase of c-myc copy numbers above 3 times were only found in 12 out of 31 non-Hodgkin's MLs (38.7%), in which 6 cases were EBV positive and 6 cases were EBV negative. In conclusion, myc gene amplification appears to play a part in MLs but no correlation was found between EBV infection and myc gene amplification.

HIV-1 protease inhibitors are substrates for the MDR1 multidrug transporter

The FDA approved HIV-1 protease inhibitors, ritonavir, saquinavir, and indinavir, are very effective in inhibiting HIV-1 replication, but their long-term efficacy is unknown. Since in vivo efficacy depends on access of these drugs to intracellular sites where HIV-1 replicates, we determined whether these protease inhibitors are recognized by the MDR1 multidrug transporter (P-glycoprotein, or P-gp), thereby reducing their intracellular accumulation. In vitro studies in isolated membrane preparations from insect cells infected with MDR1-expressing recombinant baculovirus showed that these inhibitors significantly stimulated P-gp-specific ATPase activity and that this stimulation was inhibited by SDZ PSC 833, a potent inhibitor of P-gp. Furthermore, photoaffinity labeling of P-gp with the substrate analogue [125I]iodoarylazidoprazosin (IAAP) was inhibited by all three inhibitors. Cell-based approaches to evaluate the ability of these protease inhibitors to compete for transport of known P-gp substrates showed that all three HIV-1 protease inhibitors were capable of inhibiting the transport of some of the known P-gp substrates but their effects were generally weaker than other documented P-gp modulators such as verapamil or cyclosporin A. Inhibition of HIV-1 replication by all three protease inhibitors was reduced but could be restored by MDR1 inhibitors in cells expressing MDR1. These results indicate that the HIV-1 protease inhibitors are substrates of the human multidrug transporter, suggesting that cells in patients that express the MDR1 transporter will be relatively resistant to the anti-viral effects of the HIV-1 protease inhibitors, and that absorption, excretion, and distribution of these inhibitors in the body may be affected by the multidrug transporter.

Frequent but biased class switch recombination in the S mu flanking regions

Immunoglobulin (Ig) heavy chain class switch recombination occurs mainly by joining two switch (S) regions, segments of tandemly repeated DNA sequences that lie upstream of heavy chain constant region genes. The products of this recombination event are a chromosomal DNA joint and a 'looped-out' circular DNA joint. Although a previous study showed that 40% of chromosomal joints in the mu gene switch region (S mu) are found in the flanking regions of S mu, which do not contain typical S mu region repeats [1], other studies revealed that almost all recombination sites on looped-out circular DNA are found within S regions [2-4]. To resolve this discrepancy, we have isolated and sequenced 164 DNA fragments containing recombination joints from both chromosomal and looped-out DNA of a single cell line, the murine B lymphoma line CH12F3, which switches from IgM to IgA production with a high frequency upon cytokine stimulation [5]. The recombination sites were distributed almost evenly in the S mu region and its flanking regions, suggesting that the final joining of DNA ends may not necessarily take place in S regions. In contrast, there were few joining sites in the exon located 5' of the switch region (the I mu exon), suggesting that the 3' end of the I mu exon might be the upstream border of the recombination joint.

Molecular analysis of the cDNA and genomic DNA encoding mouse RNA helicase A

RNA helicase A is an enzyme that possesses both RNA and DNA helicase activities. In this report, we describe the isolation of a mouse cDNA encoding RNA helicase A. The deduced amino acid sequence derived from mouse RNA helicase A cDNA exhibits 87 and 47% identity to its human and Drosophila homologs, respectively. Using Southern blot analysis employing a mouse backcross panel, we have assigned the mouse RNA helicase A gene to chromosome 1, mapping near the D1Bir20 locus at MGD position 67. Northern blot and primer extension analyses indicate that, although its level is variable, RNA helicase A appears to be expressed from a single transcription start site in all tissues tested. Sequence analysis of the upstream genomic DNA revealed that the promoter region lacks a TATA box and contains two high-affinity sites for Sp1, one ISRE, a binding site for interferon regulatory factor, and three AP2-binding sites. These findings suggest that the transcriptional regulation of the RNA helicase A gene is complex.

Loss of heterozygosity of the retinoblastoma and p53 genes in primary cervical carcinomas with human papillomavirus infection

OBJECTIVE

Paired DNA samples from 55 primary uterine cervical carcinomas and normal bloods were studied for chromosomal allelic loss (loss of heterozygosity; LOH) of the retinoblastoma (Rb) and p53 gene loci by polymerase chain reaction (PCR) or PCR-restriction fragment length polymorphism analysis. All the study samples contained at least one of the oncogenic human papillomavirus (HPV) type 16 and/or 18 sequences. And the relationships between allelic losses of these genes and conventional clinicopathological parameters were evaluated.

METHODS

In order to detect LOH of the Rb gene in cervical cancers, we analyzed four polymorphic intronic sites (intron 1, 17, 20, and 25) of the Rb gene and one additional microsatellite near the Rb locus (D13S118). For detection of the LOH in p53, three intragenic polymorphisms (exon 1, exon 4, intron 6) and one microsatellite distal to the p53 gene (D17S5) were examined.

RESULTS

By analyzing this system, we could increase the heterozygosity of the Rb and p53 loci up to 0.91 and 1, respectively. The observed allelic loss rates of the Rb and p53 loci in informative cases were 14% (7/50) and 5.5% (3/55), respectively. The patients with LOH at the D13S118 locus also had the allelic loss of the Rb gene, whereas only one of the four patients with LOH at the D17S5 locus showed a concomittant allelic loss of the p53 gene. The frequency of cervical cancer with one LOH at the Rb or p53 loci was 20% (11/55). No shifted bands were observed in the PCR-single-strand conformation polymorphism analysis of the p53 gene. The LOH of the Rb or p53 gene was not significantly associated with other parameters including clinical stage, histological type, degree of differentiation, status of HPV infection, and p53 gene mutation.

CONCLUSION

Concerning the results above, we conclude that the allelic imbalance of the Rb or p53 gene itself is not implicated as a major contributing factor in the malignant transformation or the tumor progression in HPV-positive uterine cervical cancers.

Establishment and characterization of a highly tumorigenic human diploid endometrial cancer cell line

A new cell line designated CUME-1 has been established from a poorly differentiated endometrial adenocarcinoma of the uterus. This cell line grew well without interruption for more than 88 months and 110 serial passages were successively carried out. The cells were highly tumorigenic in nude mice (85%). Repeated karyotype analyses from early (4th) to late (55th) passages of this cell line revealed a diploid stable clone in each passages without any noticeable structural or numerical aberrations. But from the 80th passage, a subpopulation with reciprocal translocation between chromosomes 1q and 9q consistently appeared and was observed in about 30% of the cells. This cell line is one of the rare examples of experimentally proved tumorigenic cells of human solid tumor origin that retains the diploid karyotype in vitro. HLA typing indicated the presence of DR4, DR13, DQ3 and DQ6. Cytosol estrogen and progesterone receptors were found both in fresh primary tumor and in this cell line. Gonadotropin-releasing hormone (Gn-RH) receptor mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR) in cultured cells. Using the single-strand conformation polymorphism (SSCP) technique, we have screened CUME-1 cells for p53 mutation in exons 4 to 9. No mobility shift was observed. This cell line may be useful in studying the in vitro chromosomal evolution of the cell line and the in vivo properties of human endometrial adenocarcinoma.

Efficient long-term coexpression of a hammerhead ribozyme targeted to the U5 region of HIV-1 LTR by linkage to the multidrug-resistance gene

Ribozymes as anti-HIV-1 agents hold promise for the treatment of AIDS. They can be delivered into cells either exogenously or through an expression system. For effective protection against HIV-1, sufficient and sustained amounts of the antiviral ribozymes must be delivered into target cells. The coexpression of a dominant selectable marker with ribozymes would serve to enrich for cells containing the molecular antiviral and facilitate prolonged expression of these ribozymes. The multidrug resistance gene (MDR1) is a potential clinically relevant selectable marker and offers many advantages over other known dominant selectable markers, including the use of diverse pharmacologically characterized drug or drug combinations for selection. Harvey sarcoma-based retroviral vectors encoding the MDR1 multidrug transporter with a hammerhead ribozyme targeted to highly conserved sequences within the HIV-1 U5 LTR segment have been constructed in a bicistronic format. The internal ribosome entry site (IRES) from encephalomyocarditis virus was used to initiate translation of the MDR1 mRNA. The ribozyme remained functional despite being tethered to MDR1. Long-term, high-level expression of both the ribozyme and MDR1, as evident by RT-PCR and FACS analysis, was observed in a human T cell line containing the construct selected with vincristine, a cytotoxic substrate for the multidrug transporter.

RNA helicase A mediates association of CBP with RNA polymerase II

The coactivator CBP has been proposed to stimulate the expression of certain signal-dependent genes via its association with RNA polymerase II complexes. Here we show that complex formation between CBP and RNA polymerase II requires RNA helicase A (RHA), a nuclear DNA/RNA helicase that is related to the Drosophila male dosage compensation factor mle. In transient transfection assays, RHA was found to cooperate with CBP in mediating target gene activation via the CAMP responsive factor CREB. As a mutation in RHA that compromised its helicase activity correspondingly reduced CREB-dependent transcription, we propose that RHA may induce local changes in chromatin structure that promote engagement of the transcriptional apparatus on signal responsive promoters.

The NTPase/helicase activities of Drosophila maleless, an essential factor in dosage compensation

Drosophila maleless (mle) is required for X chromosome dosage compensation and is essential for male viability. Maleless protein (MLE) is highly homologous to human RNA helicase A and the bovine counterpart of RNA helicase A, nuclear helicase II. In this report, we demonstrate that MLE protein, overexpressed and purified from Sf9 cells infected with recombinant baculovirus, possesses RNA/DNA helicase, adenosine triphosphatase (ATPase) and single-stranded (ss) RNA/ssDNA binding activities, properties identical to RNA helicase A. Using site-directed mutagenesis, we created a mutant of MLE (mle-GET) that contains a glutamic acid in place of lysine in the conserved ATP binding site A. In vitro biochemical analysis showed that this mutation abolished both NTPase and helicase activities of MLE but affected the ability of MLE to bind to ssRNA, ssDNA and guanosine triphosphate (GTP) less severely. In vivo, mle-GET protein could still localize to the male X chromosome coincidentally with the male-specific lethal-1 protein, MSL-1, but failed to complement mle1 mutant males. These results indicate that the NTPase/helicase activities are essential functions of MLE for dosage compensation, perhaps utilized for chromatin remodeling of X-linked genes.

Use of partially mismatched related donors extends access to allogeneic marrow transplant

Most patients requiring allogeneic bone marrow transplant (allo-BMT) do not have an HLA-matched sibling donor. A phenotypically matched unrelated donor graft has been made available for approximately 50% of Caucasians and less than 10% of ethnic and racial minorities in need. However, almost all patients have a readily available partially mismatched related donor (PMRD). We summarize our experience with 72 patients who ranged from 1 to 50 years of age (median, 16 years) and who were recipients of a PMRD allo-BMT from haploidentical family members following conditioning therapy using total body irradiation (TBI) and multiagent, high-dose chemotherapy. T-cell depletion and post-BMT immunosuppression were combined for graft-versus-host disease (GVHD) prophylaxis. The probability of engraftment was 0.88 at 32 days. Six of 10 patients who failed to engraft achieved engraftment after secondary transplant. Grade II to IV acute GVHD was seen in 9 of 58 (16%) evaluable patients; extensive chronic GVHD was seen in 4 of 48 (8%) evaluable patients. There was a statistically significant difference in 2-year survival probability between low-risk and high-risk patients (0.55 v 0.27, P = .048). Prognostic factors that affected outcomes in multivariate analysis were (1) a lower TBI dose and 3-antigen rejection mismatch decreased stable engraftment (P = .005 and P = .002, respectively); (2) a higher T-cell dose increased acute GVHD (P = .058); (3) a higher TBI dose increased chronic GVHD (P = .016); and (4) a high-risk disease category increased treatment failure from relapse or death (P = .037). A PMRD transplant can be performed with acceptable rates of graft failure and GVHD. Using sequential immunomodulation, the disease status at the time of transplant is the only prognostic factor significantly associated with long-term successful outcome after PMRD allo-BMT. When allogeneic rather than autologous BMT is indicated, progression in disease status before transplant can be avoided using a PMRD with equal inclusion of all ethnic or racial groups.

Advances in prevention of radiation damage to visceral and solid organs in patients requiring radiation therapy of the trunk

BACKGROUND

As a part of multimodality therapy, many patients with tumors of the trunk receive radiation therapy. The major morbidity of this therapy is often secondary to incidental radiation damage to tissues adjacent to treatment areas.

METHODS

We detail our use of saline breast implants placed in polyglycolic acid mesh sheets to displace visceral and solid organs away from the radiation field.

RESULTS

Analysis of CT scans and dose volume histograms reveal that this technique successfully displaces uninvolved organs away from the radiation fields, thereby minimizing the radiation dose to such organs and tissues.

CONCLUSION

We believe this is a safe and efficacious method to prevent radiation damage to visceral and solid organs adjacent to trunk tumor sites.

Human papillomavirus infection and TP53 gene mutation in primary cervical carcinoma

Tumor specimens obtained from 136 patients with primary carcinoma of the uterine cervix were analyzed for the presence of human papillomavirus (HPV) sequences and for mutation of the TP53 gene. Polymerase chain reaction (PCR) showed that 130 of 136 (96%) tumors contained an oncogenic HPV 16 or 18 sequence. HPV 16 was the predominant type in cervical squamous cell carcinomas and HPV 18 was significantly associated with cervical adenocarcinomas (p < 0.05). The more dedifferentiated the primary tumor, the more frequent the HPV 16 infection and the more differentiated, the more frequent the HPV 18 infection (p < 0.05). Two out of 136 (1.5%) tumors demonstrated single-strand conformation polymorphism (SSCP) band shifts. One (positive for HPV 18) had a nonsense mutation of codon 101 in exon 4 from AAA to TAA transversion. Another (positive for L1 consensus primer set) showed a point mutation involving codon 179 in exon 5 changing CAT to CGT transition. The three specimens negative for HPV did not contain TP53 gene mutations. Our data show that mutation of TP53 is infrequent in primary cervical carcinoma and there is no inverse correlation between HPV infection and TP53 gene mutation. Other mechanisms independent of TP53 inactivation may also be implicated in tumorigenesis of the uterine cervix.