Summary Mechanistic understanding of the costs and benefits of photoacclimation requires knowledge of how photophysiology is affected by changes in the molecular structure of the chloroplast. We tested the hypothesis that changes in the light dependencies of photosynthesis, nonphotochemical quenching and PSII photoinactivation arises from changes in the abundances of chloroplast proteins in Emiliania huxleyi strain CCMP 1516 grown at 30 (Low Light; LL ) and 1000 (High Light; HL ) μmol photons m −2 s −1 photon flux densities. Carbon‐specific light‐saturated gross photosynthesis rates were not significantly different between cells acclimated to LL and HL . Acclimation to LL benefited cells by increasing biomass‐specific light absorption and gross photosynthesis rates under low light, whereas acclimation to HL benefited cells by reducing the rate of photoinactivation of PSII under high light. Differences in the relative abundances of proteins assigned to light‐harvesting (Lhcf), photoprotection ( LI 818‐like), and the photosystem II ( PSII ) core complex accompanied differences in photophysiology: specifically, Lhcf: PSII was greater under LL , whereas LI 818: PSII was greater in HL . Thus, photoacclimation in E. huxleyi involved a trade‐off amongst the characteristics of light absorption and photoprotection, which could be attributed to changes in the abundance and composition of proteins in the light‐harvesting antenna of PSII .
The purpose of this study was to determine the impact of a borderline elevated postoperative carcinoembryonic antigen (CEA) on the duration of disease-free survival in patients with rectal cancer treated with postoperative adjuvant radiotherapy and chemotherapy.A retrospective review was undertaken of 145 patients undergoing curative surgery for rectal adenocarcinoma (American Joint Committee on Cancer stages II and III) and treated with postoperative radiotherapy and chemotherapy from January 1994 to February 1997. Patients with known metastatic disease, with gross residual disease after surgery, or without an available postoperative CEA level before adjuvant therapy were not included. All patients were monitored for a minimum of 1 year or until death. The rates of relapse, disease-free survival and overall survival were estimated according to the Kaplan-Meier method. Univariate analyses for the endpoint time to relapse was carried out for the following potential prognostic factors: age, gender, American Joint Committee on Cancer stage, number of lymph nodes, perineural invasion, capillary-like space invasion, margin status, and postoperative CEA level (< or = 4.0 microg/L vs > 4.0 microg/L). A mulitvariate regression analyses was conducted with the Cox proportional hazards model.With a median follow-up of 45 months, the disease-free and overall survival rates at 2 years were 78% and 90% respectively. Eight patients were identified who expressed an elevated postoperative CEA (4.1-10.2 microg/L). Two patients had T3N0 tumors; one tumor was T4N0, four tumors were T3N1, and one was T4N1. The median time to first relapse in these eight patients was 26 months, compared with 69 months for the 137 patients with a postoperative CEA in the normal range (0-4.0 microg/L), (log-rank Chi-squared test = 4.92). As determined by a proportional hazards model, an elevated CEA remained an independent predictor (along with number of positive nodes) for early relapse.Postoperative CEA in patients undergoing curative surgery for rectal cancer provides additional prognostic information in those patients embarking on adjuvant postoperative therapy. An elevated CEA predicts for early relapse and may help define a high-risk subset of patients in whom more aggressive adjuvant therapies should be considered.
Abstract: In our centre, 111 patients have been treated with linear accelerator stereotactic radiosurgery. Angiographic, CT and MRI images are generated and the target coordinates calculated in 3 dimensions. For CT scanning, cross sections of perpendicular and oblique fiducial markers are seen. For follow-up CT scans done without the frame, a virtual frame is generated by means of a computer program that places fiducial markers on each CT scan cut, as if the patient had been wearing the OBT frame and the scan produced with the gantry parallel to the base of the frame. The position of the oblique marker may be calculated by knowing the thickness and position of each CT cut. Various natural fiducial markers (bony landmarks) are identified by coordinates in the scan with the patient wearing the real frame and in the scan with the virtual frame applied. A transformation matrix is utilized to establish the equivalence between the original CT scan with the real frame applied and subsequent scans without the real frame but with the virtual frame applied. In effect, the virtual frame is re-applied in exactly the same position as the real frame. Lesion measurements may then be duplicated and growth or regression accurately established. The uncertainty in this system of re-application resides in possible patient movement, CT scan slice thickness and inter-observer error in the identification of natural fiducial markers.
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In recent years, a broader base of treatment options has evolved to improve the outcome for patients with brain metastases. The selection of the most appropriate intervention for the individual patient is dependent on a careful evaluation of the extent of intracranial tumour, as well as an understanding of patient and tumour characteristics that are important determinants of prognosis. Recent analyses have confirmed good performance status, control of the primary tumour, absence of extracranial metastases and age less than 65 years to be predictors for longer survival. Medical therapy typically includes the use of corticosteroids, and some advances have been made in optimising the use of these agents. Prophylactic use of antiepileptic drugs in patients with brain metastases is generally discouraged.
Summary Although stomata are typically found in greater numbers on the abaxial surface, wheat flag leaves have greater densities on the adaxial surface. We determine the impact of this less common stomatal patterning on gaseous fluxes using a novel chamber that simultaneously measures both leaf surfaces. Using a combination of differential illuminations and CO 2 concentrations at each leaf surface, we found that mesophyll cells associated with the adaxial leaf surface have a higher photosynthetic capacity than those associated with the abaxial leaf surface, which is supported by an increased stomatal conductance (driven by differences in stomatal density). When vertical gas flux at the abaxial leaf surface was blocked, no compensation by adaxial stomata was observed, suggesting each surface operates independently. Similar stomatal kinetics suggested some co‐ordination between the two surfaces, but factors other than light intensity played a role in these responses. Higher photosynthetic capacity on the adaxial surface facilitates greater carbon assimilation, along with higher adaxial stomatal conductance, which would also support greater evaporative leaf cooling to maintain optimal leaf temperatures for photosynthesis. Furthermore, abaxial gas exchange contributed c. 50% to leaf photosynthesis and therefore represents an important contributor to overall leaf gas exchange.
We investigated the effect of elevated partial pressure of CO 2 (pCO 2 ) on the photosynthesis and growth of four phylotypes (ITS2 types A1, A13, A2, and B1) from the genus Symbiodinium , a diverse dinoflagellate group that is important, both free‐living and in symbiosis, for the viability of cnidarians and is thus a potentially important model dinoflagellate group. The response of Symbiodinium to an elevated pCO 2 was phylotype‐specific. Phylotypes A1 and B1 were largely unaffected by a doubling in pCO 2 ; in contrast, the growth rate of A13 and the photosynthetic capacity of A2 both increased by ~ 60%. In no case was there an effect of ocean acidification (OA) upon respiration (dark‐ or light‐dependent) for any of the phylotypes examined. Our observations suggest that OA might preferentially select among free‐living populations of Symbiodinium, with implications for future symbioses that rely on algal acquisition from the environment (i.e., horizontal transmission). Furthermore, the carbon environment within the host could differentially affect the physiology of different Symbiodinium phylotypes. The range of responses we observed also highlights that the choice of species is an important consideration in OA research and that further investigation across phylogenetic diversity, for both the direction of effect and the underlying mechanism(s) involved, is warranted.
Purpose: Pseudoprogression (psPD) is now recognised following radiotherapy with concurrent temozolomide (RT/TMZ) for glioblastoma multiforme (GBM). The aim of this study was to determine the incidence of psPD following RT/TMZ and the effect of psPD on prognosis. Materials/Methods: All patients receiving RT/TMZ for newly diagnosed GBM were identified from a prospective database. Clinical and radiographic data were retrospectively reviewed. Early progression was defined as radiological progression (RECIST criteria) during or within eight weeks of completing RT/TMZ. Pseudoprogression was defined as early progression with subsequent disease stabilization, without salvage therapy, for at least six months from completion of RT/TMZ. The primary outcome was overall survival (Kaplan-Meier) and log rank analysis was used to compare groups. Results: Out of 111 patients analyzed, 104 were evaluable for radiological response. Median age was 58 years and median follow-up 55 weeks. Early progression was confirmed in 26% and within this group 32% had psPD. Median survival for the whole cohort was 56.7 weeks [95% CI (51.0, 71.3)]. Median survival for patients with psPD was significantly higher than for patients with true early progression (124.9 weeks versus 36.0 weeks, p=0.0286). Conclusions: Approximately one third of patients with early progression were found to have psPD which was associated with a favourable prognosis. Maintenance TMZ should not be abandoned on the basis of seemingly discouraging imaging features identified within the first three months after RT/TMZ.
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