Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy procedure are performed with increasing frequency to treat patients with diffused peritoneal carcinomatosis. These procedures have showed to increase...
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Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy procedure are performed with increasing frequency to treat patients with diffused peritoneal carcinomatosis. These procedures have showed to increase life expectancy in what was previously considered a "terminal condition". Anyway patients face major and life threatening derangements of their hemodynamic, respiratory and metabolic physiologic balance during the surgery and in the immediate postoperative period. Despite the need of an advanced organ monitoring and support all these derangements seem to be mild and short-lived when timely addressed, at least in the majority of patients. Intensive care physicians are involved in providing surveillance and organ support till the patient is effectively weaned after the operation. Moreover, the anesthesiologist as perioperative physician is involved in pain control, metabolic and nutritional support of this cohort of patients. This task can be challenging considering that part of the patients are already on a long list of pain control medication after previous surgery or chemotherapy. A malnourished state is common too and it is secondary to diffi cult feeding, wasting syndrome from the tumor and massive ascites. The last issue the anesthesiologists need to be aware of is the impact over the quality of life(Qo L) of this procedure. The patient's underlying pathology is unlikely to be defi nitively cured so no treatment is an acceptable choice. The possibility to withhold the treatments must be part of the consultation process like the discussion about the Qo L in the immediate, as well as in the long-term, after the operation. Careful monitoring and treatment of every aspect that can impact the Qo L must be taken and the efforts to be poured into an effective preservation of the Qo L must be doubled when compared with a patient scheduled for major abdominal surgery.
Plants need tight regulation of photosynthetic electron transport for survival and growth under environ- mental and metabolic conditions. For this purpose, the linear electron transport (LET) pathway is supple- ment...
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Plants need tight regulation of photosynthetic electron transport for survival and growth under environ- mental and metabolic conditions. For this purpose, the linear electron transport (LET) pathway is supple- mented by a number of alternative electron transfer pathways and valves. In Arabidopsis, cyclic electron transport (CET) around photosystem I (PSI), which recycles electrons from ferrodoxin to plastoquinone, is the most investigated alternative route. However, the interdependence of LET and CET and the relative importance of CET remain unclear, largely due to the difficulties in precise assessment of the contribution of CET in the presence of LET, which dominates electron flow under physiological conditions. We there- fore generated Arabidopsis mutants with a minimal water-splitting activity, and thus a low rate of LET, by combining knockout mutations in Psb01, PsbP2, PsbQ1, PsbQ2, and PsbR loci. The resulting 45 mutant is viable, although mature leaves contain only ~20% of wild-type naturally less abundant Psb02 protein. 45 plants compensate for the reduction in LET by increasing the rate of CET, and inducing a strong non-photochemical quenching (NPQ) response during dark-to-light transitions. To identify the molecular origin of such a high-capacity CET, we constructed three sextuple mutants lacking the qE component of NPQ (45 npq4-1), NDH-mediated CET (45 crr4-3), or PGR5-PGRLl-mediated CET (45 pgrS). Their analysis revealed that PGR5-PGRLl-mediated CET plays a major role in ~pH formation and induction of NPQ in C3 plants. Moreover, while pgr5 dies at the seedling stage under fluctuating light conditions, 45 pgr5 plants are able to survive, which underlines the importance of PGR5 in modulating the intersystem electron transfer.
Two homologous plastocyanin isoforms are encoded by the genes PETE1 and PETE2 in the nuclear genome of Arabidopsis thaliana. The PETE2 transcript is expressed at considerably higher levels and the PETE2 protein is the...
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Two homologous plastocyanin isoforms are encoded by the genes PETE1 and PETE2 in the nuclear genome of Arabidopsis thaliana. The PETE2 transcript is expressed at considerably higher levels and the PETE2 protein is the more abundant isoform. Null mutations in the PETE genes resulted in plants, designated pete1 and pete2, with decreased plastocyanin contents. However, despite reducing plastocyanin levels by over -90%, a pete2 null mutation on its own affects rates of photosynthesis and growth only slightly, whereas pete1 knockout plants, with about 60-80% of the wild-type plastocyanin level, did not show any alteration. Hence, plastocyanin concentration is not limiting for photosynthetic elec- tron flow under optimal growth conditions, perhaps implying other possible physiological roles for the protein. Indeed, plastocyanin has been proposed previously to cooperate with cytochrome C6A (Cyt C6A) in thylakoid redox reactions, but we find no evidence for a physical interaction between the two proteins, using interaction assays in yeast. We observed homodimerization of Cyt C6A in yeast interaction assays, but also Cyt C6A homodimers failed to interact with plastocyanin. Moreover, phenotypic analysis of atc6-1 pete1 and atc6-1 pete2 double mutants, each lacking Cyt C6A and one of the two piastocyanin-encoding genes, failed to reveal any genetic interaction. Overexpression of either PETE1 or PETE2 in the pete1 pete2 double knockout mutant background results in essentially wild-type photosynthetic performance, excluding the possibility that the two plastocyanin isoforms could have distinct functions in thylakoid electron flow.
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