Delayed diagnosis of ureteral injuries following gynecological laparoscopic surgery: three case reports and review

PURPOSE OF INVESTIGATION

The clinical manifestations, causes, and methods for the treatment and prevention of ureteral injuries presenting late after gynecological laparoscopic surgeries were investigated.

MATERIALS AND METHODS

The medical records of patients who experienced delayed recognition of ureteral injuries after gynecological laparoscopic surgeries in the present hospital between 2008 and 2012 were reviewed retrospectively.

RESULTS

There are three cases of ureteral injuries which are diagnose-delayed, The incidence of the malignant tumor groups was 0.99%, and for malignant patients undergoing laparoscopic lymphadenectomy it was 1.3%.

CONCLUSION

The main way to prevent delayed ureteral injuries is to avoid adhesion between the ureter and surrounding tissues as well as eliminate electrothermal trauma during laparoscopic operations. Surgical repair is effective for such patients.

ATF3-mediated NRF2/HO-1 signaling regulates TLR4 innate immune responses in mouse liver ischemia/reperfusion injury

Activating transcription factor 3 (ATF3) is a stress-induced transcription factor that has been shown to repress inflammatory gene expression in multiple cell types and diseases. However, little is known about the roles and mechanisms of ATF3 in liver ischemia/reperfusion injury (IRI). In warm and cold liver IRI models, we showed that ATF3 deficiency significantly increased ischemia/reperfusion (IR)-stressed liver injury, as evidenced by increased serum alanine aminotransferase levels, histological liver damage, and hepatocellular apoptosis. These may correlate with inhibition of the intrahepatic nuclear factor erythroid-derived 2-related factor 2/heme oxygenase-1 (NRF2/HO-1) signaling pathway leading to enhancing Toll-like receptor 4/nuclear factor kappa beta (TLR4/NF-κB) activation, pro-inflammatory programs and macrophage/neutrophil trafficking, while simultaneously repressing anti-apoptotic molecules in ischemic liver. Interestingly, activation of NRF2/HO-1 signaling using an NRF2 activator, oltipraz (M2), during hepatic IRI-rescued ATF3 anti-inflammatory functions in ATF3-deficient mice. For in vitro studies, ATF3 ablation in lipopolysaccharide (LPS)-stimulated bone marrow-derived macrophages (BMMs) depressed levels of NRF2/HO-1 and PI3K/AKT, resulting in enhanced TLR4/NF-κB activation. Pretreatment of LPS-stimulated BMMs with M2 increased NRF2/HO-1 expression, promoted PI3K/AKT, which in turn suppressed TLR4/NF-κB-mediated proinflammatory mediators. Thus, our results first demonstrate ATF3-mediated NRF2/HO-1 signaling in the regulation of TLR4-driven inflammatory responses in IR-stressed livers. Our findings provide a rationale for a novel therapeutic strategy for managing IR-induced liver injury.

Using pet-ct to reduce futile thoracotomy rates in non-small-cell lung cancer: a population-based review

BACKGROUND

Combined positron-emission tomography and computed tomography (pet-ct) reduces futile thoracotomy (ft) rates in patients with non-small-cell lung cancer (nsclc). We sought to identify preoperative risk factors for ft in patients staged with pet-ct.

METHODS

We retrospectively reviewed all patients referred to the BC Cancer Agency during 2009-2010 who underwent pet-ct and thoracotomy for nsclc. Patients with clinical N2 disease were excluded. An ft was defined as any of a benign lesion; an exploratory thoracotomy; pathologic N2 or N3, stage iiib or iv, or inoperable T3 or T4 disease; and recurrence or death within 1 year of surgery.

RESULTS

Of the 108 patients who met the inclusion criteria, ft occurred in 27. The main reason for ft was recurrence within 1 year (14 patients) and pathologic N2 disease (10 patients). On multivariate analysis, an Eastern Cooperative Oncology Group performance status greater than 1, a pet-ct positive N1 status, a primary tumour larger than 3 cm, and a period of more than 16 weeks from pet-ct to surgery were associated with ft. N2 disease that had been negative on pet-ct occurred in 21% of patients with a pet-ct positive N1 status and in 20% of patients with tumours larger than 3 cm and non-biopsy mediastinal staging only. The combination of pet-ct positive N1 status and a primary larger than 3 cm had 85% specificity, and the presence of either risk factor had 100% sensitivity, for ft attributable to N2 disease.

CONCLUSIONS

To reduce ft attributable to N2 disease, tissue biopsy for mediastinal staging should be considered for patients with pet-ct positive N1 status and with tumours larger than 3 cm even with a pet-ct negative mediastinum.

HRAS mutations are frequent in inverted urothelial neoplasms

Inverted urothelial papilloma (IUP) is an uncommon neoplasm of the urinary bladder with distinct morphologic features. Studies regarding the role of human papillomavirus (HPV) in the etiology of IUP have provided conflicting evidence of HPV infection. In addition, little is known regarding the molecular alterations present in IUP or other urothelial neoplasms, which might demonstrate inverted growth pattern like low-grade or high-grade urothelial carcinoma (UCA). Here, we evaluated for the presence of common driving somatic mutations and HPV within a cohort of IUPs, (n = 7) noninvasive low-grade papillary UCAs with inverted growth pattern (n = 5), and noninvasive high-grade papillary UCAs with inverted growth pattern (n = 8). HPV was not detected in any case of IUP or inverted UCA by either in situ hybridization or by polymerase chain reaction. Next-generation sequencing identified recurrent mutations in HRAS (Q61R) in 3 of 5 IUPs, described for the first time in this neoplasm. Additional mutations of Ras pathway members were detected including HRAS, KRAS, and BRAF. The presence of Ras pathway member mutations at a relatively high rate suggests this pathway may contribute to pathogenesis of inverted urothelial neoplasms. In addition, we did not find any evidence supporting a role for HPV in the etiology of IUP.

Discontinuous properties of current-induced magnetic domain wall depinning

The current-induced motion of magnetic domain walls (DWs) confined to nanostructures is of great interest for fundamental studies as well as for technological applications in spintronic devices. Here, we present magnetic images showing the depinning properties of pulse-current-driven domain walls in well-shaped Permalloy nanowires obtained using photoemission electron microscopy combined with x-ray magnetic circular dichroism. In the vicinity of the threshold current density (J_th = 4.2 × 10¹¹ A.m⁻²) for the DW motion, discontinuous DW depinning and motion have been observed as a sequence of “Barkhausen jumps”. A one-dimensional analytical model with a piecewise parabolic pinning potential has been introduced to reproduce the DW hopping between two nearest neighbour sites, which reveals the dynamical nature of the current-driven DW motion in the depinning regime.

Abstract IA6: Murine models of nonserous ovarian cancer: Effects of mutant Trp53, Pik3ca, and Arida1a in a model of endometrioid carcinoma based on Wnt and PI3K/Akt pathway defects

A dualistic pathway model of ovarian carcinoma (OvCA) pathogenesis has been proposed in which type I OvCAs are low grade, genetically stable, and relatively more indolent than type II OvCAs, most of which are high-grade serous carcinomas. Endometrioid OvCA (EOC) is a prototypical type I tumor, often harboring mutations that affect the Wnt and phosphatidylinositol 3-kinase/AKT/mTOR signaling pathways. Molecular and histopathologic analyses indicate type I and II OvCAs share overlapping features, and a subset of EOCs may undergo type I→type II progression accompanied by acquisition of somatic TP53 or PIK3CA mutations. We used a murine model of EOC initiated by conditional inactivation of the Apc and Pten tumor suppressor genes to investigate mutant Trp53 or Pik3ca alleles as key drivers of type I→type II OvCA progression. In the mouse EOC model, the presence of somatic Trp53 or Pik3ca mutations resulted in shortened survival and more widespread metastasis. In contrast, bi-allelic inactivation of Arid1a in addition to Apc and Pten actually prolonged survival and tumors with Arid1a inactivation showed more epithelial differentiation than their counterparts with intact Arid1a alleles. Our findings indicate that the adverse prognosis associated with TP53 and PIK3CA mutations in human cancers can be functionally replicated in mouse models of type I→type II OvCA progression. Moreover, the models should represent a robust platform for assessment of the contributions of Trp53, Pik3ca, and Arid1a mutations to the response of EOCs to conventional and targeted drugs.

Citation Format: Kathleen R. Cho, Rong Wu, Yali Zhai, Isao Sakaguchi. Murine models of nonserous ovarian cancer: Effects of mutant Trp53, Pik3ca, and Arida1a in a model of endometrioid carcinoma based on Wnt and PI3K/Akt pathway defects. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr IA6.

Concurrent erlotinib and radiotherapy for chemoradiotherapy-intolerant esophageal squamous cell carcinoma patients: results of a pilot study

Concurrent chemoradiotherapy is the standard treatment for patients with locally advanced esophageal squamous cell carcinoma. However, a number of patients present intolerance to chemoradiotherapy because of advanced age or malnutrition. Erlotinib, an inhibitor of epidermal growth factor receptor tyrosine kinase, was shown to be effective in treating esophageal carcinoma, with mild toxicities. In this pilot study, we investigated the safety and efficacy of concurrent erlotinib and radiotherapy as an alternative treatment modality for esophageal carcinoma patients who are intolerant to chemoradiotherapy. Pathologically diagnosed esophageal squamous cell carcinoma patients who could not tolerate concurrent chemoradiotherapy were enrolled. All patients were treated with concurrent erlotinib and intensity-modulated radiation therapy. Erlotinib was given orally for 60 days (150 mg per day). Radiotherapy (total dose, 60 Gy) was given at dosages of 2 Gy for a total of 30 times. Immunohistochemical staining was performed to assess epidermal growth factor receptor expression. Toxicities were evaluated according to the National Cancer Institute Common Terminology Criteria for Adverse Events (version 3.0). The overall survival, progression-free survival, and local-regional relapse-free survival were calculated using the Kaplan-Meier method. Between December 2007 and March 2011, 18 patients were enrolled. The median age was 71.5 years. Primary disease was stages II, III, and IV in 3, 8, and 4 patients, respectively. There were three patients with recurrent disease after radical surgery. The median follow-up time was 17.2 months. Grade 3 esophagitis and skin rash were observed in five (27.8%) and two (11.1%) patients, respectively. Radiation pneumonitis of grades 2 and 5 was observed in one patient each. No grade 3/4 impaired liver function or hematological toxicity was observed. At 1 month after radiotherapy, two (11.1%) patients achieved complete response, 11 (61.1%) patients achieved partial response, and 5 (27.8%) patients had stable disease. The median time of overall survival and progression-free survival was 21.1 and 12 months, respectively. Two-year overall survival, progression-free survival, and local-regional relapse-free survival were 44.4%, 38.9%, and 66.7%, respectively. Five of six patients examined for epidermal growth factor receptor had high expression levels (3+). The relationship between epidermal growth factor receptor expression and treatment outcomes could not be concluded. For esophageal squamous cell carcinoma patients who cannot tolerate chemoradiotherapy, concurrent erlotinib and radiotherapy are tolerable and effective. Valuable markers to predict the effect of erlotinib should be exploited in future studies.

Convection-enhanced delivery improves distribution and efficacy of tumor-selective retroviral replicating vectors in a rodent brain tumor model

In the present study, we compared the therapeutic effect of tumor-selective retroviral replicating vectors (RRV) expressing the yeast cytosine deaminase (CD) delivered by CED or simple injection, followed by systemic administration of the pro-drug, 5-fluorocytosine (5-FC). Treatment with RRV-CD and systemic 5-FC significantly increased survival in rodent U87MG glioma model in comparison to controls (p<0.01). Interestingly, CED of RRV-CD followed by 5-FC further enhanced survival in this animal model in comparison to intra-tumoral injection of RRV-CD followed by systemic 5-FC (p<0.05). High expression levels of Ki-67 were found in untreated tumors compared to treated. Untreated tumors were also much larger than treated. CED resulted in excellent distribution of RRV while only partial distribution of RRV was obtained after injection. Furthermore, RRV-CD and cytosine deaminase were also found in tumors from treated rats at study end-points. These results demonstrated that RRV vectors may efficiently transduce and stably propagate in malignant human glioma, thereby achieving a significant in-situ amplification effect after initial administration. We conclude that delivery of RRV into the glioma by CED provides much wider vector distribution than simple, injection, and this correlated with better therapeutic outcomes.

Artificial permeability and antibonding magnetic resonance in a copper-structured metamaterial with symmetry-broken ring-plate resonators

We numerically investigate the antibonding magnetic resonance in a metamaterial composed of rings and plates, with a particular attention to the influence of broken structural symmetry on the Fano-type transmission spectrum as well as the resonant artificial permeability. From the simulation results, it is obvious that the antibonding magnetic resonance with strong magnetic-dipole coupling is responsible for the Fano-type profile, since an increase of the structural asymmetry extent to reduce the magnetic field confinement in one of the gaps will form, in contrary, a Lorentzian resonance dip. The dual excitation pathways, i.e., electric and magnetic resonances, at destructive interference are the underlying reason of the Fano-type transmission response. Additionally, the structural-asymmetry dependence of the artificial permeability shows that the broken symmetry can strongly modify the effective permeability due to the altering magnetic-dipole interactions. It is found that an anti-resonant curve of permeability versus frequency will be resulted in if significant symmetry-broken structure is introduced.

Magnetic properties of (Fe50Co50)(1-x)-Gdx thin films with diluted Gd doping

(Fe50Co50)(1-x)-Gdx thin films (30 nm) with x<15% deposited on silicon substrates by magnetron sputtering were investigated by X-ray diffraction, vibrating sample magnetometer, and ferromagnetic resonance. Theoretical fittings of the angular dependent ferromagnetic resonance field of the FeCoGd films have been performed using the Landau-Lifshitz equation It is found that the ferromagnetic resonance experimental data is well fitted by the theory and various magnetic properties have been extracted in accordance. The saturation magnetization decreases from 22750 Oe at x = 0% to 14079 Oe at x = 14% in the FeCo-Gd film, and the perpendicular magnetic anisotropy has changed from an easy film plane to an easy film normal geometry. The gyromagnetic ratio, as well as the Landé g factor, are found increased also with increasing Gd content, i.e. from g = 2.08 at x = 0% to g = 2.29 at x = 14%. An enhancement of the L-S coupling in the presence of a low Gd content has been concluded based on an observable increase from 0.011 at x = 12% up to 0.015 at x = 14% in the Gilbert damping.

Disruption of Type-I IFN pathway ameliorates preservation damage in mouse orthotopic liver transplantation via HO-1 dependent mechanism

Ischemia/reperfusion injury (IRI) remains unresolved problem in clinical organ transplantation. We analyzed the role of Type-I interferon (IFN) pathway in a clinically relevant murine model of extended hepatic cold preservation followed by orthotopic liver transplantation (OLT). Livers from Type-I IFN receptor (IFNAR) knockout (KO) or wild-type (WT) mice (C57/BL6) were harvested, preserved at 4°C in UW solution for 20 h and transplanted to groups of syngeneic IFNAR KO or WT recipients. Liver graft but not recipient IFNAR deficiency was required to consistently ameliorate IRI in OLTs. Indeed, disruption of Type-I IFN signaling decreased serum alanine aminotransferase (sALT) levels (p < 0.001), diminished Suzuki's score of histological OLT damage (p < 0.01) and improved 14-day survival (from 42%[5/12] in WT to 92%[11/12] in IFNAR KO; p < 0.05). Unlike in WT group, IFNAR deficiency attenuated OLT expression of TNF-α, IL-1β, IL-6, MCP-1, CXCL-10, ICAM-1; diminished infiltration by macrophages/PMNs; and enhanced expression of antioxidant HO-1/Nrf2. The frequency of TUNEL+ apoptotic cells and caspase-3 activity/expression selectively decreased in IFNAR KO group. Small interfering (si)RNA-directed targeting of HO-1 restored cardinal features of liver IRI in otherwise resistant IFNAR-deficient OLTs. Thus, intact Type-I IFN signaling is required for hepatic IRI, whereas HO-1 is needed for cytoprotection against innate immunity-dominated organ preservation damage in IFNAR-deficient liver transplants.

Experimental validation of the largest calculated isospin-symmetry-breaking effect in a superallowed Fermi decay

A precision measurement of the γ yields following the β decay of (32)Cl has determined its isobaric-analogue branch to be (22.47(-0.18)(+0.21))%. Since it is an almost pure-Fermi decay, we can also determine the amount of isospin-symmetry breaking in this superallowed transition. We find a very large value, δ(C) = 5.3(9)%, in agreement with a shell-model calculation. This result sets a benchmark for isospin-symmetry-breaking calculations and lends support for similarly calculated, yet smaller, corrections that are currently applied to 0+ → 0 + transitions for tests of the standard model.

Mutant KRAS promotes hyperplasia and alters differentiation in the colon epithelium but does not expand the presumptive stem cell pool

BACKGROUND & AIMS

Adenomatous polyps are precursors to colorectal cancer (CRC), whereas hyperplastic polyps (HPPs) have low risk of progression to CRC. Mutations in KRAS are found in ∼40% of CRCs and large adenomas and a subset of HPPs. We investigated the reasons why HPPs with KRAS mutations lack malignant potential and compared the effects of Kras/KRAS activation with those of Apc/APC inactivation, which promotes adenoma formation.

METHODS

We activated a KrasG12D mutant allele or inactivated Apc alleles in mouse colon epithelium and analyzed phenotypes and expression of selected genes and proteins. The mouse data were validated using samples of human HPPs and adenomas. Signaling pathways and factors contributing to Kras/KRAS-induced phenotypes were studied in intestinal epithelial cells.

RESULTS

Activation of Kras led to hyperplasia and serrated crypt architecture akin to that observed in human HPPs. We also observed loss of Paneth cells and increases in goblet cell numbers. Abnormalities in Kras-mediated differentiation and proliferation required mitogen-activated protein kinase signaling and were linked to activation of the Hes1 transcription factor. Human HPPs also had activation of HES1. In contrast to Apc/APC inactivation, Kras/KRAS activation did not increase expression of crypt stem cell markers in colon epithelium or colony formation in vitro. Kras/KRAS activation was not associated with substantial induction of p16(INK4a) protein expression in mouse colon epithelium or human HPPs.

CONCLUSIONS

Although Kras/KRAS mutation promotes serrated and hyperplastic morphologic features in colon epithelium, it is not able to initiate adenoma development, perhaps in part because activated Kras/KRAS signaling does not increase the number of presumptive stem cells in affected crypts.

Liver ischemia and reperfusion injury: new insights into mechanisms of innate-adaptive immune-mediated tissue inflammation

Ischemia and reperfusion injury (IRI) is a dynamic process that involves two distinctive yet interrelated phases of ischemic organ damage and inflammation-mediated reperfusion injury. Although multiple cellular and molecular pathways contribute and regulate tissue/organ damage, integration of different players into a unified mechanism is warranted. The crosstalk between innate and adaptive immune systems plays a significant role in the pathogenesis of liver IRI. In this review, we focus on recent progress in the mechanism of liver innate immune activation by IR. Kupffer cells (KC), DCs, NK, as well as T cells initiate local inflammation response, the hallmark of IRI, by utilizing distinctive immune receptors to recognize and/or trigger various molecules, both endogenous and exogenous. The interlocked molecular signaling pathways in the context of multiple liver cell types, the IRI kinetics and positive versus negative regulatory loops in the innate immune activation process are discussed. Better appreciation of molecular interactions that mediate these intricate cascades, should allow for the development of novel therapeutic approached against IRI in liver transplant recipients.

Comparative serum proteomic analysis of patients with acute-on-chronic liver failure: alpha-1-acid glycoprotein maybe a candidate marker for prognosis of hepatitis B virus infection

The acute-on-chronic liver failure (AoCLF) caused by hepatitis B virus (HBV) infection remains to be a challenge in clinics with a high mortality rate in China, and it is important to identify biomarkers to foresee the prognosis of patients with HBV. The current study analysed serum proteome changes of acute-on-chronic liver failure as a result of acute exacerbation of chronic hepatitis B infection. Serum samples were collected from normal subjects (NS, n = 8), patients with chronic hepatitis B (CHB, n = 12) and patients with AoCLF (n = 12). After removal of albumin/IgG and ultramembrane centrifugation, serum proteins were separated by two-dimensional gel electrophoresis. Differentially expressed spots were identified by matrix-associated laser desorption ionization time-of-flight tandem mass spectrometry. Through the removal of albumin/IgG and ultramembrane centrifugation, the well-resolved and reproducible two-dimensional gel electrophoresis (2-DE) profiles were obtained. A total of 23 proteins were identified on 2-DE profiles by their differential expression between the three cohorts. Mass spectrometry analysis resulted in the identification of 12 proteins unambiguously. Western blot analysis confirmed the proteomics results that the α1-acid glycoprotein (α1-AGP) levels decrease significantly in plasma of patients with AoCLF, but somewhat decreased in patients with chronic HBV. Further α1-AGP levels in bulk serum samples were measured by immune turbidimetry including normal subjects group (n = 25), acute hepatitis group (n = 36), chronic hepatitis group (n = 52) and AoCLF group (n = 48), the level of α1-AGP in AoCLF groups sharply decrease than other groups. Our study shows that α1-AGP may be a potential plasma biomarker for AoCLF diagnosis because of acute exacerbation of chronic hepatitis B infection.

Loss of estrogen receptor 1 enhances cervical cancer invasion

If left untreated, some cervical high-grade squamous intraepithelial lesions will progress to invasive squamous cell carcinoma (SCC), but the molecular events conferring invasive potential remain poorly defined. In prior work, we identified 48 genes that were down-regulated in SCCs compared with high-grade squamous intraepithelial lesions and normal squamous epithelia. In this study, a functional screening strategy was used to identify which of these genes regulate cervical cancer cell invasion. Two independent squamous epithelial cell lines were transduced with a library of short hairpin RNAs targeting the differentially expressed genes and tested for invasion of the chick chorioallantoic membrane. PCR was used to recover specific short hairpin RNAs from cells that invaded the chorioallantoic membrane. Constructs targeting estrogen receptor 1 (ESR1) were highly enriched in the invasive cells. The short hairpin RNA-mediated inhibition of ESR1 in SCC- and precancer-derived cell lines increased invasiveness in both in vivo and in vitro assays. Conversely, restoration of ESR1 expression in ESR1-negative cervical cancer cells reduced cell invasiveness. Loss of ESR1 expression was found to accompany cervical cancer progression in an analysis of primary normal cervix, low grade squamous intraepithelial lesions, high-grade squamous intraepithelial lesions, and SCC specimens. Molecular mechanisms underlying down-regulation of ESR1 in invasive cervical carcinomas appear to be complex and likely heterogeneous. Our findings indicate that loss of ESR1 has a major role in mediating cervical cancer invasion and progression.

COMMD1 disrupts HIF-1alpha/beta dimerization and inhibits human tumor cell invasion

The gene encoding COMM domain-containing 1 (COMMD1) is a prototypical member of the COMMD gene family that has been shown to inhibit both NF-kappaB- and HIF-mediated gene expression. NF-kappaB and HIF are transcription factors that have been shown to play a role in promoting tumor growth, survival, and invasion. In this study, we demonstrate that COMMD1 expression is frequently suppressed in human cancer and that decreased COMMD1 expression correlates with a more invasive tumor phenotype. We found that direct repression of COMMD1 in human cell lines led to increased tumor invasion in a chick xenograft model, while increased COMMD1 expression in mouse melanoma cells led to decreased lung metastasis in a mouse model. Decreased COMMD1 expression also correlated with increased expression of genes known to promote cancer cell invasiveness, including direct targets of HIF. Mechanistically, our studies show that COMMD1 inhibits HIF-mediated gene expression by binding directly to the amino terminus of HIF-1alpha, preventing its dimerization with HIF-1beta and subsequent DNA binding and transcriptional activation. Altogether, our findings demonstrate a role for COMMD1 in tumor invasion and provide a detailed mechanism of how this factor regulates the HIF pathway in cancer cells.

Differential requirement of CD27 costimulatory signaling for naïve versus alloantigen-primed effector/memory CD8+ T cells

CD8(+) memory T cells endanger allograft survival by causing acute and chronic rejection and prevent tolerance induction. We explored the role of CD27:CD70 T-cell costimulatory pathway in alloreactive CD8(+)/CD4(+) T-cell activation. CD27-deficient (CD27(-/-)) and wild-type (WT) B6 mice rejected BALB/c cardiac allografts at similar tempo, with or without depletion of CD4(+) or CD8(+) T cells, suggesting that CD27 is not essential during primary T-cell alloimmune responses. To dissect the role of CD27 in primed effector and memory alloreactive T cells, CD27(-/-) or WT mice were challenged with BALB/c hearts either 10 or 40 days after sensitization with donor-type skin grafts. Compared to WT controls, allograft survival was prolonged in day 40- but not day 10-sensitized CD27(-/-) recipients. Improved allograft survival was accompanied by diminished secondary responsiveness of memory CD8(+) T cells, which resulted from deficiency in memory formation rather than their lack of secondary expansion. Chronic allograft vasculopathy and fibrosis were diminished in CD27(-/-) recipients of class I- but not class II-mismatched hearts as compared to WT controls. These data establish a novel role for CD27 as an important costimulatory molecule for alloreactive CD8(+) memory T cells in acute and chronic allograft rejection.

Impact of pulse forming network and injection current parameters on output and energy variations of helical tomotherapy

PURPOSE

In this study, an experiment was devised to establish the dependency of the impact of pulse forming network (PFN) and injection current (IC) parameters on output and energy variations of helical tomotherapy (HT) on the radiation beam output and energy.

METHODS

HT has unique radiation beam characteristics due to the absence of a flattening filter. As with conventional linear accelerators, the machine output and energy should be within a + or - 2% tolerance according to published studies. However, because a dose servo is not utilized in a HT unit, these parameters may drift out of the + or - 2% tolerance due to various reasons such as high machine temperatures. With this in mind, physicists and engineers must adjust certain machine parameters to reset the output and energy to within the tolerance of the commissioned baseline. Two parameters commonly adjusted are: PFN voltage (V(PFN)) and IC voltage (V(IC)).

RESULTS

Results showed that the HT unit possesses different working zones defined by the V(PFN) and V(IC) parameter settings. The working zones were classified into 5 zones: 1) low dose rate zone - radiation dose rate much lower than nominal dose rate and machine cannot run due to low dose rate fault; 2) normal dose rate zone - dose rate is within tolerance of nominal dose rate and machine can run without dose rate fault; 3) dose rate failure during treatment zone - dose rate within the tolerance of the nominal dose rate however machine interrupts during treatment due to dose rate fault; 4) high dose rate zone - dose rate is higher than nominal dose rate and machine cannot run due to high dose rate fault; and 5) inoperable dose rate zone - dose rate is much higher than the nominal dose rate and machine cannot run.

CONCLUSION

The results of this study may provide a quick guide for physicists to adjust their HT unit V(PFN) and V(IC) values in order to reset the radiation beam output and energy back to within the tolerance of the commissioned baseline.