Mechanism for APOBEC3G catalytic exclusion of RNA and non-substrate DNA.

The potent antiretroviral protein APOBEC3G (A3G) specifically targets and deaminates deoxycytidine nucleotides, generating deoxyuridine, in single stranded DNA (ssDNA) intermediates produced during HIV replication. A non-catalytic domain in A3G binds strongly to RNA, an interaction crucial for recruitment of A3G to the virion; yet, A3G displays no deamination activity for cytidines in viral RNA. Here, we report NMR and molecular dynamics (MD) simulation analysis for interactions between A3Gctd and multiple substrate or non-substrate DNA and RNA, in combination with deamination assays. NMR ssDNA-binding experiments revealed that the interaction with residues in helix1 and loop1 (T201-L220) distinguishes the binding mode of substrate ssDNA from non-substrate. Using 2'-deoxy-2'-fluorine substituted cytidines, we show that a 2'-endo sugar conformation of the target deoxycytidine is favored for substrate binding and deamination. Trajectories of the MD simulation indicate that a ribose 2'-hydroxyl group destabilizes the π-π stacking of the target cytosine and H257, resulting in dislocation of the target cytosine base from the catalytic position. Interestingly, APOBEC3A, which can deaminate ribocytidines, retains the ribocytidine in the catalytic position throughout the MD simulation. Our results indicate that A3Gctd catalytic selectivity against RNA is dictated by both the sugar conformation and 2'-hydroxyl group.

Impact of H216 on the DNA binding and catalytic activities of the HIV restriction factor APOBEC3G.

APOBEC3G has an important role in human defense against retroviral pathogens, including HIV-1. Its single-stranded DNA cytosine deaminase activity, located in its C-terminal domain (A3Gctd), can mutate viral cDNA and restrict infectivity. We used time-resolved nuclear magnetic resonance (NMR) spectroscopy to determine kinetic parameters of A3Gctd's deamination reactions within a 5'-CCC hot spot sequence. A3Gctd exhibited a 45-fold preference for 5'-CCC substrate over 5'-CCU substrate, which explains why A3G displays almost no processivity within a 5'-CCC motif. In addition, A3Gctd's shortest substrate sequence was found to be a pentanucleotide containing 5'-CCC flanked on both sides by a single nucleotide. A3Gctd as well as full-length A3G showed peak deamination velocities at pH 5.5. We found that H216 is responsible for this pH dependence, suggesting that protonation of H216 could play a key role in substrate binding. Protonation of H216 appeared important for HIV-1 restriction activity as well, since substitutions of H216 resulted in lower restriction in vivo.

Immunogenicity of an inactivated monovalent 2009 influenza A (H1N1) vaccine in patients who have cancer.

BACKGROUND: The immune response of patients who have cancer, who may be receiving immunosuppressive therapy, is generally considered to be decreased. This study aimed to evaluate the immune response of cancer patients to the 2009 influenza A (H1N1) vaccine. PATIENTS AND METHODS: We conducted a prospective single site study comparing the immune response after H1N1 vaccination of healthy controls (group A), patients who had solid tumors and were taking myelosuppressive chemotherapy (group B), patients who had solid tumors and were taking nonmyelosuppressive or no treatment (group C), and patients who had hematologic malignancies (group D). RESULTS: At 2-6 weeks after vaccination, seroconversion was observed in 80.0% of group A (95% confidence interval [CI], 65.0%-89.7%), 72.2% of group B (95% CI, 55.9%-84.3%), 87.0% of group C (95% CI, 72.2%-94.7%), and 75.0% of group D (95% CI, 52.8%-89.2%) (p = NS). The geometric mean titer ratio, that is, geometric mean factor increase in antibody titer after vaccination, was 12.6 (95% CI, 7.9-19.9), 12.7 (95% CI, 7.3-22.1), 23.0 (95% CI, 13.9-38.2), and 12.1 (95% CI, 5.3-27.9) (p = NS), and the seroprotection rates were 95.5% (95% CI, 84.0%-99.6%), 79.0% (95% CI, 63.4%-89.2%), 90.5% (95% CI, 77.4%-96.8%), and 90.0% (95% CI, 71%-98.7%) in the corresponding groups (p = NS). Immune responses were robust regardless of malignancy, or time intervals between the use of myelosuppressive or immunosuppressive medications and vaccination. No participants developed clinical H1N1 infection. CONCLUSION: Cancer patients, whether taking myelosuppressive chemotherapy or not, are able to generate an immune response to the H1N1 vaccine similar to that of healthy controls.

Mucocele-like Lesions of the Breast.

Mucocele-like lesions of the breast (MLL) are believed to be due to mucinous ducts extruding their contents into the surrounding stroma. MLLs are a rare entity usually identified by calcifications noted on routine screening mammography. Surgical excision has been recommended due to the propensity for these lesions to harbor atypical ductal hyperplasia (ADH) or malignancy. A 44-year-old female patient presented to the breast center after undergoing routine mammography which showed a group of coarse appearing microcalcifications in the outer third of the breast. After further workup, a core needle biopsy was obtained with pathology showing benign breast tissue with acellular stromal mucin pools containing dystrophic calcifications. The patient underwent surgical excision with final pathology revealing ductal carcinoma in-situ and ADH with prominent mucin production throughout the stroma.

Cancer worry and insomnia complaints among American women.

One-third of women worrying about breast cancer report impaired ability to function daily. It is unclear whether women who worry about breast cancer would experience more sleep problems than those who do not. Data were obtained from a cross-sectional study of black and white women to investigate the association between breast cancer worry and insomnia complaints. Several questionnaires were administered during face-to-face interviews to elicit health and sociodemographic data. The present analyses focused on black and white women (n = 1,038; age range = 50-70 years) with no cancer antecedents or history. Overall, 62% of the women worried about breast cancer, and 49% reported insomnia complaints. Logistic regression analyses, adjusting for effects of age, ethnicity, family history, and perceived risk of developing breast cancer, yielded an odds ratio for insomnia complaints of 1.52 (95% CI: 1.15-2.02, p < .001) among women reporting breast cancer worry. More than one half of the women worrying about breast cancer were likely to report insomnia complaints, notwithstanding the fact that those women did not have a history of cancer. Although fewer black women reported breast cancer worry and insomnia complaints, they were as affected as white women by the impact of worry on mood and daily activities.

A Diagnostic Surprise: Primary Hodgkin's Lymphoma of the Lung.

An 81-year-old male presented to the emergency room with a 3-month history of progressive shortness of breath, productive cough with white sputum, and generalized weakness with 10-pound weight loss in 2 months. On presentation, the patient was afebrile, with blood pressure of 93/55 mm Hg and oxy-hemoglobin saturation of 92% on 2 liters of oxygen via nasal cannula. Complete blood count with differential was significant for white count of 12 400/mL. Brain natriuretic peptide level was 454 ng/mL. Postero-anterior chest radiograph showed multiple round opacities in the lung fields. Computed tomography scan of the chest confirmed multiple round densities in both the lung fields along with mild mediastinal lymphadenopathy. Core needle biopsy was performed. Immunohistochemical stains were positive for CD30 and CD15 in a population of large atypical cells amid a background of CD3-positive nonneoplastic cells. These results were in support of the diagnosis of classical Hodgkin's lymphoma of the lung with histological appearance confirming nodular sclerosis type. The patient was started on chemotherapy but was readmitted in 20 days for acute respiratory distress and suffered cardiac arrest and subsequently died. This case highlights the fact that although primary pulmonary Hodgkin's lymphoma of the lung is a rare entity, it should be thought of as a differential while evaluating lung masses. In these cases, definite diagnosis can only be made by biopsy and histology. Early commencement of chemotherapy and regular follow-up with oncology is essential.

Rare Case of Spinal Cord Compression as Initial Presentation of Thymic Carcinoma.

Thymic carcinomas are rare aggressive cancers with limited clinical trial data. Its usual treatment is surgical resection with variable response to chemotherapy and radiation. It usually presents as anterior mediastinal mass with late sequela of metastases to the lymph nodes, pleura and bones. We present of thymic carcinoma with a rare initial presentation of vertebral metastases causing spinal cord compression.

Prostatic Lymphoma Masquerading as Urinary Retention and Hematuria With Review of Literature.

Lymphomas of prostate are very rare tumors. They are not commonly considered in the clinical and histological differential diagnosis of prostatic enlargement. We report a case of a 49-year-old man who presented to emergency department with several weeks of difficulty in urination, for which he was being treated for benign prostate hyperplasia with no improvement. Computerized tomography scan showed lobulated mass originating from the superior aspect of the prostate with right inguinal lymph node involvement and no distant organ metastatic disease. Prostatic biopsy revealed diffuse large B-cell lymphoma. The patient achieved complete remission after six cycles of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone chemotherapy regimen. Lymphomas of the prostate should be considered in differential diagnosis of the patient presenting with obstructive lower urinary tract symptoms especially in patients with normal prostatic-specific antigen level and previous history of lymphoma in other sites.

Enhanced resting-state dynamics of the hemoglobin signal as a novel biomarker for detection of breast cancer.

PURPOSE: The work presented here demonstrates an application of diffuse optical tomography (DOT) to the problem of breast-cancer diagnosis. The potential for using spatial and temporal variability measures of the hemoglobin signal to identify useful biomarkers was studied. METHODS: DOT imaging data were collected using two instrumentation platforms the authors developed, which were suitable for exploring tissue dynamics while performing a simultaneous bilateral exam. For each component of the hemoglobin signal (e.g., total, oxygenated), the image time series was reduced to eight scalar metrics that were affected by one or more dynamic properties of the breast microvasculature (e.g., average amplitude, amplitude heterogeneity, strength of spatial coordination). Receiver-operator characteristic (ROC) analyses, comparing groups of subjects with breast cancer to various control groups (i.e., all noncancer subjects, only those with diagnosed benign breast pathology, and only those with no known breast pathology), were performed to evaluate the effect of cancer on the magnitudes of the metrics and of their interbreast differences and ratios. RESULTS: For women with known breast cancer, simultaneous bilateral DOT breast measures reveal a marked increase in the resting-state amplitude of the vasomotor response in the hemoglobin signal for the affected breast, compared to the contralateral, noncancer breast. Reconstructed 3D spatial maps of observed dynamics also show that this behavior extends well beyond the tumor border. In an effort to identify biomarkers that have the potential to support clinical aims, a group of scalar quantities extracted from the time series measures was systematically examined. This analysis showed that many of the quantities obtained by computing paired responses from the bilateral scans (e.g., interbreast differences, ratios) reveal statistically significant differences between the cancer-positive and -negative subject groups, while the corresponding measures derived from individual breast scans do not. ROC analyses yield area-under-curve values in the 77%-87% range, depending on the metric, with sensitivity and specificity values ranging from 66% to 91%. An interesting result is the initially unexpected finding that the hemodynamic-image metrics are only weakly dependent on the tumor burden, implying that the DOT technique employed is sensitive to tumor-induced changes in the vascular dynamics of the surrounding breast tissue as well. Computational modeling studies serve to identify which properties of the vasomotor response (e.g., average amplitude, amplitude heterogeneity, and phase heterogeneity) principally determine the values of the metrics and their codependences. Findings from the modeling studies also serve to clarify the influence of spatial-response heterogeneity and of system-design limitations, and they reveal the impact that a complex dependence of metric values on the modeled behaviors has on the success in distinguishing between cancer-positive and -negative subjects. CONCLUSIONS: The authors identified promising hemoglobin-based biomarkers for breast cancer from measures of the resting-state dynamics of the vascular bed. A notable feature of these biomarkers is that their spatial extent encompasses a large fraction of the breast volume, which is mainly independent of tumor size. Tumor-induced induction of nitric oxide synthesis, a well-established concomitant of many breast cancers, is offered as a plausible biological causal factor for the reported findings.

Artesunate-related fever and delayed hemolysis in a returning traveler.

Malaria is a serious and sometimes fatal disease caused by an intraerythrocytic parasite, and is commonly seen in developing countries. Approximately 1500 cases of malaria are diagnosed in the United States each year, mostly in travelers and immigrants returning from endemic areas [1]. There are many different regimens used to treat malaria, some of which are not approved in the USA. The side effects of these medications may not be familiar to physicians in the USA. We report a case of a returning traveler from Nigeria presenting with fever and hemolytic anemia caused by a delayed response to artesunate given 3 weeks earlier while in Nigeria. To our knowledge, there are few cases reported in the United States of hemolytic anemia secondary to artesunate therapy [2].

A critical analysis of prognostic factors in North American patients with human T-cell lymphotropic virus type-1-associated adult T-cell leukemia/lymphoma: a multicenter clinicopathologic experience and new prognostic score.

BACKGROUND: To define the clinicopathologic and prognostic features of patients with human T-cell lymphotropic virus type-1 (HTLV-1)-associated adult T-cell leukemia/lymphoma (ATLL) in North America, standard criteria were used to identify patients with ATLL. METHODS: Statistical analyses used included descriptive statistics, Kaplan-Meir survival analysis, and recursive partitioning. RESULTS: Eighty-nine patients were identified between August 1992 and May 2007, including 37 (41.6%) males and 52 (58.4%) females with a median age of 50 years (range, 22-82 years). All but 6 patients had immigrated to the United States from the Caribbean, Latin America, or Africa. The acute subtype predominated (68.5%). The majority of patients received a combination-alkylator-based chemotherapy regimen in the front-line setting (72.6%). The most common regimen was cyclophosphamide, doxorubicin, vincristine, and prednisone at standard doses or attenuated and/or with methotrexate (CHOP-like), which produced an overall response rate of 64.1%. Despite initial responses to therapy, the median overall survival for all subtypes was 24 weeks (range, 0.9-315 weeks). Although the International Prognostic Index and Prognostic Index for peripheral T-cell lymphoma unspecified identified subsets of patients, these models were not completely predictive. A recursive partitioning analysis was performed on the data, which successfully identified 3 prognostic categories based on Eastern Cooperative Oncology Group performance status, stage, age, and calcium level at diagnosis. CONCLUSIONS: This series proposed a new prognostic model for patients with HTLV-1-associated ATLL and confirmed a poor outcome for these patients in North America.

Prokaryotic ubiquitin-like protein pup is intrinsically disordered.

The prokaryotic ubiquitin-like protein Pup targets substrates for degradation by the Mycobacterium tuberculosis proteasome through its interaction with Mpa, an ATPase that is thought to abut the 20S catalytic subunit. Ubiquitin, which is assembled into a polymer to similarly signal for proteasomal degradation in eukaryotes, adopts a stable and compact structural fold that is adapted into other proteins for diverse biological functions. We used NMR spectroscopy to demonstrate that, unlike ubiquitin, the 64-amino-acid protein Pup is intrinsically disordered with small helical propensity in the C-terminal region. We found that the Pup:Mpa interaction involves an extensive contact surface that spans S21-K61 and that the binding is in the "slow exchange" regime on the NMR time scale, thus demonstrating higher affinity than most ubiquitin:ubiquitin receptor pairs. Interestingly, during the titration experiment, intermediate Pup species were observable, suggesting the formation of one or more transient state(s) upon binding. Moreover, Mpa selected one configuration for a region undergoing chemical exchange in the free protein. These findings provide mechanistic insights into Pup's functional role as a degradation signal.

Design and implementation of dynamic near-infrared optical tomographic imaging instrumentation for simultaneous dual-breast measurements.

Dynamic near-infrared optical tomographic measurement instrumentation capable of simultaneous bilateral breast imaging, having a capability of four source wavelengths and 32 source-detector fibers for each breast, is described. The system records dynamic optical data simultaneously from both breasts, while verifying proper optical fiber contact with the tissue through implementation of automatic schemes for evaluating data integrity. Factors influencing system complexity and performance are discussed, and experimental measurements are provided to demonstrate the repeatability of the instrumentation. Considerations in experimental design are presented, as well as techniques for avoiding undesirable measurement artifacts, given the high sensitivity and dynamic range (1:10(9)) of the system. We present exemplary clinical results comparing the measured physiologic response of a healthy individual and of a subject with breast cancer to a Valsalva maneuver.

Airborne pollen: a brief life.

The transfer of pollen, whether it is transported by insects or carried by the wind, from floral anther to recipient stigma is the critical reproductive event among higher plants. In this scenario, the pollen grain functions as a fully constituted life-cycle stage, capable of growth (albeit limited) and delivery of gametes. Pollen is prepared for this role by an intricate developmental process with dual sources of structural elements and chemical constituents, including allergens. The resulting complexity relates, at least in part, to the requirements of an unforgiving recognition process at stigmatic surfaces and of active growth before the achievement of gametic union. Recently, the basic participants in pollen-stigma interactions have been defined, and they provide a striking counterpoint to human histocompatibility concerns. Pollen development offers a useful tableau in terms of which to reexamine forces affecting pollen prevalence and their interactions. Development also provides clues to the sources and significance of more minute bioaerosols now known to carry pollen allergens.

How ill the wind? Issues in aeroallergen sampling.

The effective size of bioaerosols is the principal determinant of their behavior during takeoff, transport, and deposition. Collection methods involving impaction, impingement, and filtration allow recovery of increasingly small aerosol units and do so "per unit volume of processed air" with more or less well-defined efficiency. These principles offer direction in choosing sampling devices for specific applications; similarly, a particle's appearance, growth potential, and assayability define the scope of relevant analyses. Where a variety of aerosol types occur, multiple collection and/or analytic approaches might be required. The development of a sampling grid in North America makes possible studies of distribution, transport, and climatic effects in ways never previously possible; however, some directive planning and oversight are essential to realize these goals. Methods sensitive to paucimicronic and submicronic particles should be included increasingly in new and ongoing survey protocols. Similarly, available means now facilitate study of aerosols at specific sites, both indoors and outdoors, with estimates of personal exposure during defined events. Resulting data describing airborne prevalence gain special value in light of competent inspection of implicated venues and consideration of alternative sources, such as incursion of bioaerosols into enclosed spaces.