Using a photon phase-space source for convolution/superposition dose calculations in radiation therapy

For a given linac design, the dosimetric characteristics of a photon beam are determined uniquely by the energy and radial distributions of the electron beam striking the x-ray target. However, in the usual commissioning of a beam from measured data, a large number of variables can be independently tuned, making it difficult to derive a unique and self-consistent beam model. For example, the measured dosimetric penumbra in water may be attributed in various proportions to the lateral secondary electron range, the focal spot size and the transmission through the tips of a non-divergent collimator; the head-scatter component in the tails of the transverse profiles may not be easy to resolve from phantom scatter and head leakage; and the head-scatter tails corresponding to a certain extra-focal source model may not agree self-consistently with in-air output factors measured on the central axis. To reduce the number of adjustable variables in beam modelling, we replace the focal and extra-focal sources with a single phase-space plane scored just above the highest adjustable collimator in a EGS/BEAM simulation of the linac. The phase-space plane is then used as photon source in a stochastic convolution/superposition dose engine. A photon sampled from the uncollimated phase-space plane is first propagated through an arbitrary collimator arrangement and then interacted in the simulation phantom. Energy deposition kernel rays are then randomly issued from the interaction points and dose is deposited along these rays. The electrons in the phase-space file are used to account for electron contamination. 6 MV and 18 MV photon beams from an Elekta SL linac are used as representative examples. Except for small corrections for monitor backscatter and collimator forward scatter for large field sizes (<0.5% with <20 x 20 cm2 field size), we found that the use of a single phase-space photon source provides accurate and self-consistent results for both relative and absolute dose calculations.     

HCV-specific CD27- CD28- memory T cells are depleted in hepatitis C virus and Schistosoma mansoni co-infection

Factors that influence the generation and maintenance of memory CD8+ T cells are not fully understood. The homeostasis of memory T cells is highly dynamic and tightly regulated by various stimuli, including cytokines and antigen-major histocompatibility complex ligands. We characterized the hepatitis C virus (HCV)-specific CD8+ T-cell responses in a cohort of HCV-infected individuals with or without Schistosoma mansoni co-infection from Egypt. We observed a significantly decreased CD27- CD28- (late differentiated) memory T-cell population in the HCV co-infected individuals compared to those with HCV infection alone. In contrast, there was no significant difference in the CD27+ CD28+ (early differentiated) memory T cells between the two groups. Analysis of human cytomegalovirus-specific CD8+ T-cell responses in the same individuals failed to reveal a similar pattern of altered memory T-cell differentiation. Thus, S. mansoni co-infection targets a specific subset of memory CD8+ T cells in HCV infection.     

Stromal CD10 expression in mammary fibroadenomas and phyllodes tumours

BACKGROUND/AIMS: CD10 (CALLA) has recently been reported to be expressed in spindle cell neoplasia, and has been used to differentiate endometrial stromal sarcoma from leiomyoma and leiomyosarcoma. In the breast, myoepithelial cells express CD10, but there are few studies of the expression of CD10 in mammary fibroepithelial lesions. METHODS: Stromal CD10 expression was studied in 181 mammary phyllodes tumours (102 benign, 51 borderline malignant, and 28 frankly malignant) and 33 fibroadenomas using immunohistochemistry, to evaluate whether differences in expression correlated with the degree of malignancy. RESULTS: There was a progressive increase in the patients' age and tumour size, from fibroadenoma to phyllodes tumours with an increasing degree of malignancy (p < 0.001). Stromal CD10 expression was positive in one of 33 fibroadenomas, six of 102 benign phyllodes tumours, 16 of 51 borderline malignant phyllodes tumours, and 14 of 28 frankly malignant phyllodes tumours. The difference was significant (p < 0.001) and an increasing trend was established. Strong staining was seen in subepithelial areas with higher stromal cellularity and activity. Stromal CD10 expression had a high specificity (95%) for differentiating between benign lesions (fibroadenomas and benign phyllodes tumours) and malignant (borderline and frankly malignant) phyllodes tumours. CONCLUSIONS: CD10 may be a useful adjunct in assessing malignancy in mammary fibroepithelial lesions.     

Wasting during pregnancy increases the risk of mother-to-child HIV-1 transmission

OBJECTIVES: To examine whether wasting during pregnancy, as measured by weight loss and low weight gain, is associated with increased mother-to-child transmission (MTCT) of HIV-1. METHODS: This was a cohort study in Dar es Salaam, Tanzania, among 957 HIV-1-infected pregnant women. Weight was measured at the first prenatal visit and every month thereafter until delivery. Weight loss was defined as a weekly rate of weight gain 0 and /=167 g/wk, weight loss during pregnancy was related to higher risk of intrauterine MTCT (adjusted relative risk [RR] = 2.32, 95% CI = 1.23-4.36, P = 0.009), HIV positive at birth or fetal death (RR = 2.13, 95% CI = 1.40-3.24, P = 0.0004), and HIV positive at birth or early neonatal death (RR = 1.96, 95% CI = 1.26-3.07, P = 0.003). The rate of weight gain during the 3rd trimester was inversely related to the risk of intrapartum/early breast-feeding transmission (adjusted P value, test for trend = 0.05). CONCLUSIONS: Weight loss during pregnancy increases the risk of early MTCT. Identifying causes of wasting during pregnancy may provide clues for new strategies to prevent MTCT.     

Endplate channel actions of a hemicholinium-3 analog,DMAE

Summary The effect of the hemicholium-3 analog, DMAE, on endplate currents (EPC) was investigated in the transected cutaneous pectoris muscle of the frog using a conventional two-microelectrode voltage clamp. At a low concentration (5 M), DMAE produced a long-lasting decrease in the rate constant of decay () and an increase in the peak current amplitude (Ip). At higher concentrations (10–100 M), DMAE produced biphasic changes characterized by a transient, marked decrease of and increase of Ip followed by a long-lasting marked increase of and decrease of Ip. When DMAE was removed from the bath recovery from block was asymmetrical in that recovered more quickly than did Ip. Pretreatment with neostigmine or collagenase partially antagonized the initial effects without affecting the steady state effects of DMAE, indicating that the initial effects of DMAE may be, at least in part, due to inhibition of the enzyme acetylcholinesterase. The drug reverses the normal voltage dependence of without altering the single exponential nature of decay of the EPC. The inward EPC was more markedly blocked than outward EPC, resulting in a highly non-linear current-voltage relation with Ip decreasing with increasing hyperpolarization. This effect may indicate that DMAE causes a voltage-dependent block of closed acetylcholine-activated ion channels.     

Discovery and Validation of a Urinary Exosome mRNA Signature for the Diagnosis of Human Kidney Transplant Rejection

BackgroundDeveloping a noninvasive clinical test to accurately diagnose kidney allograft rejection is critical to improve allograft outcomes. Urinary exosomes, tiny vesicles released into the urine that carry parent cells’ proteins and nucleic acids, reflect the biologic function of the parent cells within the kidney, including immune cells. Their stability in urine makes them a potentially powerful tool for liquid biopsy and a noninvasive diagnostic biomarker for kidney-transplant rejection.MethodsUsing 192 of 220 urine samples with matched biopsy samples from 175 patients who underwent a clinically indicated kidney-transplant biopsy, we isolated urinary exosomal mRNAs and developed rejection signatures on the basis of differential gene expression. We used crossvalidation to assess the performance of the signatures on multiple data subsets.ResultsAn exosomal mRNA signature discriminated between biopsy samples from patients with all-cause rejection and those with no rejection, yielding an area under the curve (AUC) of 0.93 (95% CI, 0.87 to 0.98), which is significantly better than the current standard of care (increase in eGFR AUC of 0.57; 95% CI, 0.49 to 0.65). The exosome-based signature’s negative predictive value was 93.3% and its positive predictive value was 86.2%. Using the same approach, we identified an additional gene signature that discriminated patients with T cell–mediated rejection from those with antibody-mediated rejection (with an AUC of 0.87; 95% CI, 0.76 to 0.97). This signature’s negative predictive value was 90.6% and its positive predictive value was 77.8%.ConclusionsOur findings show that mRNA signatures derived from urinary exosomes represent a powerful and noninvasive tool to screen for kidney allograft rejection. This finding has the potential to assist clinicians in therapeutic decision making.     

Trends in management of ureteral urothelial carcinoma and effects on survival: a hospital-based registry study

BackgroundHigh-risk ureteral tumors represent an understudied subset of upper tract urothelial carcinoma, whose surgical management can range from a radical nephroureterectomy (NU) to segmental ureterectomy (SU).ObjectivesTo evaluate contemporary trends in the management of high-risk ureteral tumors, the utilization of lymphadenectomy and peri-operative chemotherapy, and their impact on overall survival (OS).Design, setting, and participantsWe performed a retrospective cohort study of patients in the National Cancer Database from years 2006 to 2013 with clinically localized high-risk ureteral tumors treated with NU or SU.Outcome measurements and statistical analysisChi-squared tests were utilized to assess differences in clinicodemographic features and peri-operative treatment delivery between SU and NU cohorts. Cochran-Armitage tests and linear regressions were performed to evaluate temporal trends in treatment utilization. Multivariable logistic regression models were employed to assess predictors of treatment delivery. Multivariable Cox proportional hazards models evaluated associations with OS.ResultsOf the 1,962 patients included, NU was more commonly performed than SU (72.4%, 1,421/1,962 vs. 27.6%, 541/1,962). Only 22.7% (446/1,962) of the population underwent lymphadenectomy, and 24.8% (271/1,092) of those with advanced pathology (≥pT2 or pN+) received adjuvant chemotherapy. Lymphadenectomy was associated with improved OS in NU patients when more than 3 nodes were removed (hazard ratio [HR] 0.58, 95% confidence interval [CI] 0.39–0.89). Receipt of adjuvant chemotherapy for advanced pathology had no impact OS in both the NU (HR 1.10, 95% CI 0.84–1.44) and SU (HR 0.94, 95% CI 0.61–1.46) cohorts. Performance of SU was not associated with poorer OS on multivariable analysis (HR 1.02, 95% CI 0.89–1.21, P = 0.83).ConclusionOur study suggests that SU may be an appropriate alternative to NU for the management of high-risk ureteral tumors. Further, lymphadenectomy may play an important role at the time of NU, and adjuvant chemotherapy is infrequently utilized in patients with advanced pathology.     

Surgical and non-surgical treatment of inguinal hernia during non-elective admissions in the Nationwide Readmissions Database

Hernia - Inguinal hernia repair is one of the most common surgical operations, yet the optimal treatment strategy remains undefined. Treatment of symptomatic inguinal hernias include both surgical...     

Scarf osteotomy for hallux valgus deformity: Radiological outcome,metatarsal length and early complications in 118 feet

BackgroundScarf osteotomy has been widely used to restore axial orientation of the first ray in the treatment of hallux valgus deformity. The aim of the study was to present our radiological outcomes of bunion reconstruction, identify surgical complications in early follow-up, and assess to what extent a shortening of the first metatarsal is present after surgery as a possible cause of postoperative metatarsalgia.MethodsWe enrolled 106 patients (118 feet) and assessed patients’ pre- and postoperative measurements of hallux valgus and intermetatarsal angles on weightbearing X-ray images. Three different methods of measuring metatarsal length were compared and early postoperative complications noted.ResultsHallux valgus angle decreased significantly by an average of 18.7 degrees and the intermetatarsal angle by 7.8 degrees. Using three methods of measuring metatarsal length, all showed significant shortening of the first metatarsal. Mean relative lengthening of the second metatarsal averaged 0.45 mm. The Coughlin method showed the highest interrater reliability (ICC = 0.96).ConclusionsSignificant reduction of the hallux valgus angle and intermetatarsal angle was demonstrated with a low complication rate. There was significant shortening of the first metatarsal. The Coughlin method clearly demonstrated an excellent interrater reliability.Level of evidenceLevel IV.