A PLETHORA/PIN-FORMED/auxin network mediates prehaustorium formation in the parasitic plant Striga hermonthica.

The parasitic plant Striga (Striga hermonthica) invades the host root through the formation of a haustorium and has detrimental impacts on cereal crops. The haustorium results from the prehaustorium, which is derived directly from the differentiation of the Striga radicle. The molecular mechanisms leading to radicle differentiation shortly after germination remain unclear. In this study, we determined the developmental programs that regulate terminal prehaustorium formation in S. hermonthica at cellular resolution. We showed that shortly after germination, cells in the root meristem undergo multiplanar divisions. During growth, the meristematic activity declines and associates with reduced expression of the stem cell regulator PLETHORA1 and the cell cycle genes CYCLINB1 and HISTONE H4. We also observed a basal localization of the PIN-FORMED (PIN) proteins and a decrease in auxin levels in the meristem. Using the structural layout of the root meristem and the polarity of outer-membrane PIN proteins, we constructed a mathematical model of auxin transport that explains the auxin distribution patterns observed during S. hermonthica root growth. Our results reveal a fundamental molecular and cellular framework governing the switch of S. hermonthica roots to form the invasive prehaustoria.

Cell Dynamics in WOX5-Overexpressing Root Tips: The Impact of Local Auxin Biosynthesis.

Root stem cell niche functioning requires the formation and maintenance of the specific "auxin-rich domain" governed by directional auxin transport and local auxin production. Auxin maximum co-localizes with the WOX5 expression domain in the quiescent center that separates mitotically active proximal and distal root meristems. Here we unravel the interconnected processes happening under WOX5 overexpression by combining in vivo experiments and mathematical modeling. We showed that WOX5-induced TAA1-mediated auxin biosynthesis is the cause, whereas auxin accumulation, PIN transporters relocation, and auxin redistribution between proximal and distal root meristems are its subsequent effects that influence the formation of the well-described phenotype with an enlarged root cap. These findings helped us to clarify the role of WOX5, which serves as a local QC-specific regulator that activates biosynthesis of non-cell-autonomous signal auxin to regulate the distal meristem functioning. The mathematical model with WOX5-mediated auxin biosynthesis and auxin-regulated cell growth, division, and detachment reproduces the columella cells dynamics in both wild type and under WOX5 dysregulation.

Rocks in the auxin stream: Wound-induced auxin accumulation and ERF115 expression synergistically drive stem cell regeneration.

Plants are known for their outstanding capacity to recover from various wounds and injuries. However, it remains largely unknown how plants sense diverse forms of injury and canalize existing developmental processes into the execution of a correct regenerative response. Auxin, a cardinal plant hormone with morphogen-like properties, has been previously implicated in the recovery from diverse types of wounding and organ loss. Here, through a combination of cellular imaging and in silico modeling, we demonstrate that vascular stem cell death obstructs the polar auxin flux, much alike rocks in a stream, and causes it to accumulate in the endodermis. This in turn grants the endodermal cells the capacity to undergo periclinal cell division to repopulate the vascular stem cell pool. Replenishment of the vasculature by the endodermis depends on the transcription factor ERF115, a wound-inducible regulator of stem cell division. Although not the primary inducer, auxin is required to maintain ERF115 expression. Conversely, ERF115 sensitizes cells to auxin by activating ARF5/MONOPTEROS, an auxin-responsive transcription factor involved in the global auxin response, tissue patterning, and organ formation. Together, the wound-induced auxin accumulation and ERF115 expression grant the endodermal cells stem cell activity. Our work provides a mechanistic model for wound-induced stem cell regeneration in which ERF115 acts as a wound-inducible stem cell organizer that interprets wound-induced auxin maxima.

Human AlphoidtetO Artificial Chromosome as a Gene Therapy Vector for the Developing Hemophilia A Model in Mice.

Human artificial chromosomes (HACs), including the de novo synthesized alphoidtetO-HAC, are a powerful tool for introducing genes of interest into eukaryotic cells. HACs are mitotically stable, non-integrative episomal units that have a large transgene insertion capacity and allow efficient and stable transgene expression. Previously, we have shown that the alphoidtetO-HAC vector does not interfere with the pluripotent state and provides stable transgene expression in human induced pluripotent cells (iPSCs) and mouse embryonic stem cells (ESCs). In this study, we have elaborated on a mouse model of ex vivo iPSC- and HAC-based treatment of hemophilia A monogenic disease. iPSCs were developed from FVIIIY/- mutant mice fibroblasts and FVIII cDNA, driven by a ubiquitous promoter, was introduced into the alphoidtetO-HAC in hamster CHO cells. Subsequently, the therapeutic alphoidtetO-HAC-FVIII was transferred into the FVIIIY/- iPSCs via the retro-microcell-mediated chromosome transfer method. The therapeutic HAC was maintained as an episomal non-integrative vector in the mouse iPSCs, showing a constitutive FVIII expression. This study is the first step towards treatment development for hemophilia A monogenic disease with the use of a new generation of the synthetic chromosome vector-the alphoidtetO-HAC.

A Sacrifice-for-Survival Mechanism Protects Root Stem Cell Niche from Chilling Stress.

Temperature has a profound influence on plant and animal development, but its effects on stem cell behavior and activity remain poorly understood. Here, we characterize the responses of the Arabidopsis root to chilling (low but above-freezing) temperature. Chilling stress at 4°C leads to DNA damage predominantly in root stem cells and their early descendants. However, only newly generated/differentiating columella stem cell daughters (CSCDs) preferentially die in a programmed manner. Inhibition of the DNA damage response in these CSCDs prevents their death but makes the stem cell niche more vulnerable to chilling stress. Mathematical modeling and experimental validation indicate that CSCD death results in the re-establishment of the auxin maximum in the quiescent center (QC) and the maintenance of functional stem cell niche activity under chilling stress. This mechanism improves the root's ability to withstand the accompanying environmental stresses and to resume growth when optimal temperatures are restored.

How multiple auxin responsive elements may interact in plant promoters: a reverse problem solution.

Plant hormone auxin is a key regulator of growth and development. Auxin affects gene expression through ARF transcription factors, which bind specifically auxin responsive elements (AuxREs). Auxin responsive genes usually have more than one AuxRE, for example, a widely used auxin sensor DR5 contains seven AuxREs. Auxin responsive regions of several plant genes have been studied using sets of transgenic constructions in which the activity of one or several AuxREs were abolished. Here we present the method for analysis of the datasets on promoter activity assays having promoter sequences, namely, number and sequences of AuxREs, altogether with their measured auxin induction level. The method for a reverse problem solution considers two extreme models of AuxRE cooperation. Additive model describes auxin induction level of a gene as a sum of the individual AuxREs impacts. Multiplicative model considers pure cooperation between the AuxREs, where the combined effect is the multiplication of the individual AuxRE impacts. The reverse problem solution allows estimating the impact of an individual AuxRE into the induction level and the model for their cooperation. For promoters of three genes belonging to different plant species we showed that the multiplicative model fits better than additive. The reverse problem solution also suggests repressive state of auxin responsive promoters before auxin induction. The developed method provides possibility to investigate AuxRE structure-activity relationship and may be used as the basis for a novel approach for AuxRE recognition.

Aggressive non-Hodgkin's lymphoma mimicking unilateral transitional cell carcinoma of renal pelvis. The risk of making a diagnostic mistake.

A 78-year-old Caucasian man was referred to our department because of an incidental unilateral mass involving the right renal sinus. As the patient showed no urological disease at flexible ureterorenoscopy, a subsequent percutaneous CT-targeted biopsy was mandatory, confirming an aggressive non-Hodgkin disease involving the renal pelvis that is, to the best of our knowledge, the second reported case in literature. A whole body FDG-PET excluded multiple expression of this disease, and the patient underwent a chemotherapeutic scheme resulting in a stable marked reduction in tumor volume. To the date, the available experience on the management and outcome of such cases is extremely lean. In this scenario, our case can contribute to shorten the time-to-diagnosis by reporting a complete images overview comprising abdominal CT scan, MRI and FDG-PET-CT, hence making this clinical entity easier presumable in clinical daily practice and offering a possible suggestion for an effective treatment.

Neurological syndrome after R-CHOP chemotherapy for a non-Hodgkin lymphoma: what is the diagnosis?

A 63-year-old man was admitted to our Oncology department for management of a follicular non-Hodgkin lymphoma, stage IV A FLIPI 5. The patient entered chemotherapy following the R-CHOP schedule, and a PET scan after three cycles showed partial remission. One week later he was admitted to our hospital after developing serious pain in his left arm resulting in an impaired function, right facial hemiplegia, and ophthalmoplegia. Neuroimaging studies and laboratory features were negative. Given his symptoms, we suspected Miller Fisher syndrome and the patient was administered high dose immunoglobulin, but showed no improvement. Finally, chemotherapy with methotrexate 3 g/mq was initiated, but his condition progressively worsened and the patient died 2 months later. We suggest that any patient with neurological symptoms who has received rituximab should undergo PCR analysis for all neurotropic viruses together with neurophysiological and neuroimaging studies.

Intrathecal chemotherapy in lymphomatous meningitis.

Central Nervous System (CNS) involvement in lymphoma can occur whether at diagnosis or, more often, at the progression or recurrence of disease and the most frequent clinical manifestation is lymphomatous meningitis (LM). The first risk factor for LM development is the histotype, with the highest incidence for highly aggressive non-Hodgkin's lymphomas (NHL) such as Burkitt's lymphoma (BL) and lymphoblastic lymphoma/acute lymphoblastic leukemia (LBL/ALL) and the lowest for indolent NHL. LM prophylaxis in aggressive NHL (other than BL and LBL/ALL) is a much debated question, because the identification of specific risk factors remains controversial. Moreover, there is not a consensus if the LM prophylaxis should consist of systemic chemotherapy (CT), intrathecal (i.t.) CT or both. In case of LM, the i.t. CT has a key role, but there is not a consensus on treatment schedule. Newer intensified regimens and rituximab lead to reconsider the whole approach to LM.

Optic pathway glioma: long-term visual outcome in children without neurofibromatosis type-1.

BACKGROUND: Little is known about the visual outcome of children affected by an optic pathway glioma (OPG). PROCEDURES: We evaluated the long-term visual outcome of 32 consecutive children affected by OPG without neurofibromatosis type-1 referred to the Pediatric Department of Padua University and managed according to standardized strategies. RESULTS: Eight children received chemotherapy, 10 radiotherapy, 7 both chemotherapy and radiotherapy, whereas 7 were untreated. At presentation, visual acuity (VA) was normal in 22 children (13 unilaterally and 9 bilaterally), and reduced in 10. At follow-up, VA had improved in 6 patients; it was stable in 8 and worse in 18. Visual field, assessed in 29 children, was normal in 9 and reduced in 20. The number of children with some grade of visual impairment increased from 7 to 10 during follow-up. Of the 17 children in whom the tumor became significantly smaller, VA improved in 6, was stable in 3, and worse in 8. Of the 6 children with improved VA, 5 received radiotherapy, and their papilla was normal or mildly pale. After a median follow-up of 6 years, 26 patients are alive with stable disease. CONCLUSIONS: The visual prognosis of children with OPG is unsatisfactory. Older children treated with radiotherapy seem to have a better visual outcome than younger children. Severe optic pallor at diagnosis or during follow-up may be indicative of a negative prognosis.

Management of Frail and Not-Frail elderly cancer patients in a hospital-based geriatric oncology program.

PURPOSE: To evaluate management and outcome of patients >or=70 years admitted to our Medical Oncology ward and evaluated by Multidimensional Geriatric Assessment before treatment with standard or "elderly-friendly" chemotherapy regimens, a list of which was developed within our Geriatric Oncology Program based on published clinical trials and personal experience. PATIENTS AND METHODS: Charts of patients treated from January 2004 to January 2006 were reviewed for choice of treatment, tumor response, toxicities and survival. RESULTS: 117 patients (median age 75 years) were divided into Frail (F) (34.2%) and Not-Frail patients (NF: 33.3% Fit plus 32.5% Vulnerable). The two groups did not differ according to the use of "elderly-friendly"chemotherapy regimens (40% of F pts and 39% of NF pts), dose reductions >or=25% (37.5% vs. 31.2%) and grade 3-4 toxicities (52.5% vs. 58.4%). Early interruption of treatment due to toxicity or patient's refusal (42.5 vs. 15.6, p=0.001) and deaths within 30 days from last chemotherapy administration (22.5% vs. 3.9%, p=0.003) were significantly different. F patients showed clinical or radiological response in 21.2% of cases, and subjective improvement in 22.6%. After a median follow-up of 19 months, median survival of F patients (6.4 months) is shorter compared to NF group (16.9 months, p=0.012). CONCLUSIONS: The use of "elderly-friendly"chemotherapy regimens was limited to less than a half of cases. F patients may respond to chemotherapy but display higher rates of premature withdrawal and early deaths compared to NF patients, with a shorter survival. Clinical trials particularly aimed at frail patients are urgently needed.

Increasing chemotherapy in small-cell lung cancer: from dose intensity and density to megadoses.

The hypothesis that increasing cytotoxic dose intensity will improve cancer cure rates is compelling. Although supporting evidence for this hypothesis has accrued for several tumor types, including lymphomas, breast cancer, and testicular cancers, it remains unproven. Small-cell lung cancer is extremely chemo- and radiosensitive, with a response rate of 80% achieved routinely, but few patients are cured by chemoradiotherapy. In this setting, increased cytotoxic dose intensity might improve cure rates. The finding that response rates in small-cell lung cancer correlate with received cytotoxic dose intensity merely confirms that "less is worse" and "more is better." Within conventional ranges, dose intensity can be increased with the support of hematopoietic growth factors and/or by shortening treatments intervals; however, dose intensity could be increased by only 20%-30%, and a survival advantage has not been clearly demonstrated. Given its high chemosensitivity, small-cell lung cancer was one of the first malignancies deemed suitable for increasing dose intensity and even for the use of a megadose with the support of autologous bone marrow transplantation. Some interest is emerging again due to improvements in supportive care, such as the availability of hematopoietic growth factors and peripheral blood progenitor cells.

Occurrence of post-transplant lymphoproliferative disorders among over thousand adult recipients: any role for hepatitis C infection?

BACKGROUND: Post-transplant lymphoproliferative disorders represent an increasingly important complication of organ transplantation. Although the majority of the post-transplant lymphoproliferative disorder are etiologically related to Epstein-Barr virus infection other factors may play a role. Hepatitis C virus may induce clonal expansion of B-lymphocytes and has been associated with extrahepatic lymphoproliferative disorders. OBJECTIVES: In this study, we have evaluated: (i) the prevalence of post-transplant lymphoproliferative disorder; (ii) presence of Epstein-Barr virus in post-transplant lymphoproliferative disorder tissue; and (iii) the potential association between post-transplant lymphoproliferative disorder development and hepatitis C virus infection in a large cohort of adult solid organ transplant recipients. METHODS: The study involved 1011 liver, heart and kidney-transplanted patients. Different immunosuppression therapy was recorded from all patients, all were screened for hepatitis C virus infection. When post-transplant lymphoproliferative disorder developed, Epstein-Barr virus encoded RNA by in-situ hybridization and EBNA-1 and gp220 by polymerase chain reaction was assessed in tissue samples. RESULTS: The overall prevalence of post-transplant lymphoproliferative disorder was 1.4% (2.5% in heart, 0.9% in liver and 0.8% in kidney-transplanted patients) and significantly higher in hepatitis C virus positive than in hepatitis C virus negative patients (3.6 % vs 1.2 %; P=0.04). Epstein-Barr virus was present in 10 (77%) out of 13 tumors tested. Two out of three Epstein-Barr virus-negative post-transplant lymphoproliferative disorder developed in hepatitis C virus-positive patients. Thirteen out of 15 (86%) post-transplant lymphoproliferative disorder patients had undergone antithymocyte globulin/OKT3 induction therapy. CONCLUSIONS: Epstein-Barr virus, induction immunosuppression, rejection therapy and also hepatitis C virus infection may play a role in the multifactorial pathogenesis of post-transplant lymphoproliferative disorder.

Long-term clinical outcome of AIDS-related Kaposi's sarcoma during highly active antiretroviral therapy.

The long-term impact of highly active antiretroviral therapy (HAART) in AIDS patients with Kaposi's sarcoma (KS) was evaluated in 22 consecutive, HAART-naïve KS patients attending a single Italian referral centre for HIV/AIDS. Clinical, virologic and immunologic responses to HAART were assessed at baseline and every three months during the follow-up. Peripheral blood mononuclear cell (PBMC)-associated human herpesvirus 8 (HHV-8) load was also evaluated by real-time PCR in 13 patients with durable clinical KS complete response (CR). In a median follow-up of 40 months (range 17-78), the KS overall clinical response rate was 91%: 18 complete and 2 partial responses were achieved, and two patients experienced disease progression. CR persisted in all 18 patients, including the 5 poor-risk KS patients in whom CR lasted for > 60 months, and was significantly linked to an increase in CD4+ cell counts and a drop in HIV-1-RNA copies. Compared to baseline levels, a decrease in PBMC HHV-8 load was observed at CR, and a significant further reduction was found at the end of follow-up. In this monocentric study, AIDS-KS patients treated with HAART showed high clinical response rate. Patients with CR showed a prolonged remission, lasting more than 5 years in a group of poor-risk patients, and a persistent reduction in circulating HHV-8-infected cells. These findings highlight that HAART deeply modifies the natural history of this tumour in AIDS patients, and that this long-lasting approach may be considered a first-line treatment for the majority of HIV-1-infected patients developing KS.

Treatments of AIDS-related Kaposi's sarcoma.

Although Kaposi's sarcoma (KS) has decreased in countries where the highly active antiretroviral therapy (HAART) regimen is available, however it remains, after non-Hodgkin's lymphomas, the most common malignancy in HIV+ patients. Advances in the treatment of AIDS-KS have been achieved, even though a gold standard therapy has not been yet defined. With the availability of HAART, a dramatic KS clinical response has been documented, making HAART essential in all patients. In case of aggressive and/or life threatening KS, more complex therapeutic schedules have to be taken into account, including chemotherapy and/or immunotherapy. Liposomal anthracyclines and paclitaxel have been approved by FDA as first line and second line mono-therapy, respectively. Interferon-alpha (INF-alpha) is the only immunomodulant agent to have shown a therapeutic effect. Among the new drugs, many antiangiogenetic agents have produced encouraging responses. Finally, the identification of the HHV-8 as a causative agent and new metalloproteinase inhibitors may offer promising targets for the KS treatment.

Novel pharmacological therapies for the treatment of AIDS-related Kaposi's sarcoma.

Kaposi's sarcoma (KS) is the most common cancer associated with AIDS. KS aetiology and pathogenesis are still poorly defined and no definitive treatment has yet been identified. However, the introduction in 1996 of highly active antiretroviral therapy as a standard of care for those infected with HIV-1 determined a strong protection against the development of opportunistic infections, as well as a remission of pre-existing complications, including KS. Under highly active antiretroviral therapy, KS in particular has shown the highest clinical response rate reported to date among AIDS patients. Furthermore, recent insights into the pathogenetic mechanisms involved in KS development have provided new hope for a response and improved survival in patients with AIDS-related KS. This paper presents an overview of the current knowledge concerning pharmacological approaches to treating this disease. Newer treatments such as PEGylated liposomal anthracyclin, paclitaxel and pathogenesis-based strategies are also discussed.

Respiratory syncytial virus-related pneumonia after stem cell transplantation successfully treated with palivizumab and steroid therapy.

A case is reported of a 56-y-old woman with a second relapse of Hodgkin's disease who early developed after autologous stem cell transplantation (ASCT) a severe RSV-related interstitial pneumonia successfully treated with 1-d intravenous palivizumab 8 mg/kg plus low-dose systemic steroid therapy. B-cells suppression with CMV antigenaemia were then observed and required treatment with ganciclovir and liposomal amfotericine B.