Cerclage wire or positional cortical screw for the treatment of intraoperative calcar fractures during primary total hip arthroplasty? A biomechanical study.

BACKGROUND: During primary total hip arthroplasty, intra-operative calcar fractures have been historically treated with cerclage wires. However, interfragmentary screw fixation technique can possibly achieve the same results with technical advantages. The aim of this biomechanical study was to assess stability of calcar fractures fixed using interfragmentary screw technique compared to a traditional cerclage system specifically in context of total hip arthroplasty. METHODS: Thirty-two periprosthetic fractures were reduced using either a single cerclage cable or an intracortical positional screw perpendicular to the fracture line. Axial and torsional load testing was terminated after experimental model failure. FINDINGS: No significant difference was obtained for all output parameters when comparing cerclage wires versus interfragmentary screw fixation respectively. Load at failure: 8043 ± 712 N vs 7425 ± 854 N (p = 0.115). Load at calcar fracture propagation: 6240 ± 2207 N versus 6220 ± 966 N (p = 0.668). Maximum stiffness before failure: 617 ± 115 N/mm vs 839 ± 175 N/mm (p = 0.100) and stiffness at calcar fracture propagation reached 771 ± 153 Nmm vs 886 ± 129 N/mm (p = 0.197). Torque to failure levels obtained were 59.4 ± 7.1 N*m vs 60.9 ± 12.0 N*m (p = 0.908). Torque to calcar fracture propagation, 51.6 ± 6.1 N*m vs 48.5 ± 9.8 N*m (p = 0.298). Torsional stiffness at failure, 0.38 ± 0.03 N*m\deg. vs 0.43 ± 0.13 N*m\deg. (p = 0.465). Torsional stiffness at calcar fracture propagation were 0.37 ± 0.03 N*m\deg. vs 0.45 ± 0.17 N*m\deg. (p = 0.462). INTERPRETATION: The strength of fixation and stability of the implant were similar for both techniques. In the synthetic bone model tested, using an interfragmentary screw conveyed similar stability to the constructs in the management of an intra-operative medial calcar fractures. Thus, potentially giving surgeons an alternative option for intraoperative fracture fixation during primary total hip arthroplasty.

Does labral treatment technique influence the outcome of FAI surgery? A matched-pair study of labral reconstruction versus repair and debridement with a follow-up of 10 years.

The aim of this study was to analyze the long-term clinical outcomes of labral reconstruction in patients undergoing femoro-acetabular impingement (FAI) surgery and compare them with labral repair and debridement. This is a single-center, single-surgeon, retrospective match-paired study from a prospectively collected hip preservation database. All patients underwent a hip surgical dislocation for FAI surgery. Eight patients underwent labral reconstruction with the ligamentum teres and were matched on sex, age and body mass index with 24 labral repair and 24 labral debridement (1:3). Failure was defined as conversion to total hip replacement (THR) and patient-reported outcome measures (PROMs) were collected. Mean follow-up was 9.8 years ±2.6 (5.2-13.9). There was a significant improvement in postoperative PROMs in the three groups regarding the WOMAC total, WOMAC function, HOOS-QoL, HOOS-ADL and HOOS-SRA (P < 0.05). There was no statistical difference between the three groups regarding postoperative PROMs and change in PROMs (P > 0.05). A total of 10 hips underwent joint replacement surgery at a mean time of 7.9 ± 3.5 years (2.4-12). There was no statistically significant difference between the three groups regarding the conversion rate to THR (P = 0.64) or time between surgery and conversion to THR (P = 0.15). Compared to a match-pair group of labral repair and debridement, labral reconstruction with ligamentum teres provides similar survival with conversion to a THR as an endpoint, as well as similar improvement in PROMs. Labral treatment can be safely adapted at the nature of the labral lesion with a treatment 'à la carte'.

Wheat yield potential in controlled-environment vertical farms.

Scaling current cereal production to a growing global population will be a challenge. Wheat supplies approximately one-fifth of the calories and protein for human diets. Vertical farming is a possible promising option for increasing future wheat production. Here we show that wheat grown on a single hectare of land in a 10-layer indoor vertical facility could produce from 700 ± 40 t/ha (measured) to a maximum of 1,940 ± 230 t/ha (estimated) of grain annually under optimized temperature, intensive artificial light, high CO2 levels, and a maximum attainable harvest index. Such yields would be 220 to 600 times the current world average annual wheat yield of 3.2 t/ha. Independent of climate, season, and region, indoor wheat farming could be environmentally superior, as less land area is needed along with reuse of most water, minimal use of pesticides and herbicides, and no nutrient losses. Although it is unlikely that indoor wheat farming will be economically competitive with current market prices in the near future, it could play an essential role in hedging against future climate or other unexpected disruptions to the food system. Nevertheless, maximum production potential remains to be confirmed experimentally, and further technological innovations are needed to reduce capital and energy costs in such facilities.

Is the Kok effect a respiratory phenomenon? Metabolic insight using 13 C labeling in Helianthus annuus leaves.

The Kok effect is a well-known phenomenon in which the quantum yield of photosynthesis changes abruptly at low light. This effect has often been interpreted as a shift in leaf respiratory metabolism and thus used widely to measure day respiration. However, there is still no formal evidence that the Kok effect has a respiratory origin. Here, both gas exchange and isotopic labeling were carried out on sunflower leaves, using glucose that was 13 C-enriched at specific C-atom positions. Position-specific decarboxylation measurements and NMR analysis of metabolites were used to trace the fate of C-atoms in metabolism. Decarboxylation rates were significant at low light (including above the Kok break point) and increased with decreasing irradiance below 100 µmol photons m-2  s-1 . The variation in several metabolite pools such as malate, fumarate or citrate, and flux calculations suggest the involvement of several decarboxylating pathways in the Kok effect, including the malic enzyme. Our results show that day respiratory CO2 evolution plays an important role in the Kok effect. However, the increase in the apparent quantum yield of photosynthesis below the Kok break point is also probably related to malate metabolism, which participates in maintaining photosynthetic linear electron flow.

Leaf Carbon Export and Nonstructural Carbohydrates in Relation to Diurnal Water Dynamics in Mature Oak Trees.

Trees typically experience large diurnal depressions in water potential, which may impede carbon export from leaves during the day because the xylem is the source of water for the phloem. As water potential becomes more negative, higher phloem osmotic concentrations are needed to draw water in from the xylem. Generating this high concentration of sugar in the phloem is particularly an issue for the ∼50% of trees that exhibit passive loading. These ideas motivate the hypothesis that carbon export in woody plants occurs predominantly at night, with sugars that accumulate during the day assisting in mesophyll turgor maintenance or being converted to starch. To test this, diurnal and seasonal patterns of leaf nonstructural carbohydrates, photosynthesis, solute, and water potential were measured, and carbon export was estimated in leaves of five mature (>20 m tall) red oak (Quercus rubra) trees, a species characterized as a passive loader. Export occurred throughout the day at equal or higher rates than at night despite a decrease in water potential to -1.8 MPa at midday. Suc and starch accumulated over the course of the day, with Suc contributing ∼50% of the 0.4 MPa diurnal osmotic adjustment. As a result of this diurnal osmotic adjustment, estimates of midday turgor were always >0.7 MPa. These findings illustrate the robustness of phloem functioning despite diurnal fluctuations in leaf water potential and the role of nonstructural carbohydrates in leaf turgor maintenance.

Management of cervical spine epidural abscess: a systematic review.

BACKGROUND: Cervical spinal epidural abscess (CSEA) is a localized infection between the thecal sac and cervical spinal column which may result in neurological deficit and death if inadequately treated. Two treatment options exist: medical management and surgical intervention. Our objective was to analyze CSEA patient outcomes in order to determine the optimal method of treatment. METHODS: An electronic literature search for relevant case series and retrospective reviews was conducted through June 2016. Data abstraction and study quality assessment were performed by two independent reviewers. A lack of available data led to a post hoc decision not to perform meta-analysis of the results; study findings were synthesized qualitatively. RESULTS: 927 studies were identified, of which 11 were included. Four studies were ranked as good quality, and seven ranked as fair quality. In total, data from 173 patients were included. Mean age was 55 years; 61.3% were male. Intravenous drug use was the most common risk factor for CSEA development. Staphylococcus aureus was the most commonly cultured pathogen. 140 patients underwent initial surgery, an additional 18 patients were surgically treated upon failure of medical management, and 15 patients were treated with antibiotics alone. CONCLUSION: The rates of medical management failure described in our review were much higher than those reported in the literature for thoracolumbar spinal epidural abscess patients, suggesting that CSEA patients may be at a greater risk for poor outcomes following nonoperative treatment. Thus, early surgery appears most viable for optimizing CSEA patient outcomes. Further research is needed in order to corroborate these recommendations.

Diagnostic Accuracy of Serum, Synovial, and Tissue Testing for Chronic Periprosthetic Joint Infection After Hip and Knee Replacements: A Systematic Review.

BACKGROUND: Chronic periprosthetic joint infection (PJI) is a devastating complication that can occur following total joint replacement. Patients with chronic PJI report a substantially lower quality of life and face a higher risk of short-term mortality. Establishing a diagnosis of chronic PJI is challenging because of conflicting guidelines, numerous tests, and limited evidence. Delays in diagnosing PJI are associated with poorer outcomes and morbid revision surgery. The purpose of this systematic review was to compare the diagnostic accuracy of serum, synovial, and tissue-based tests for chronic PJI. METHODS: This review adheres to the Cochrane Collaboration's diagnostic test accuracy methods for evidence searching and syntheses. A detailed search of MEDLINE, Embase, the Cochrane Library, and the grey literature was performed to identify studies involving the diagnosis of chronic PJI in patients with hip or knee replacement. Eligible studies were assessed for quality and bias using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. Meta-analyses were performed on tests with sufficient data points. Summary estimates and hierarchical summary receiver operating characteristic (HSROC) curves were obtained using a bivariate model. RESULTS: A total of 12,616 citations were identified, and 203 studies met the inclusion criteria. Of these 203 studies, 170 had a high risk of bias. Eighty-three unique PJI diagnostic tests were identified, and 17 underwent meta-analyses. Laboratory-based synovial alpha-defensin tests and leukocyte esterase reagent (LER) strips (2+) had the best performance, followed by white blood-cell (WBC) count, measurement of synovial C-reactive protein (CRP) level, measurement of the polymorphonuclear neutrophil percentage (PMN%), and the alpha-defensin lateral flow test kit (Youden index ranging from 0.78 to 0.94). Tissue-based tests and 3 serum tests (measurement of interleukin-6 [IL-6] level, CRP level, and erythrocyte sedimentation rate [ESR]) had a Youden index between 0.61 to 0.75 but exhibited poorer performance compared with the synovial tests mentioned above. CONCLUSIONS: The quality of the literature pertaining to chronic PJI diagnostic tests is heterogeneous, and the studies are at a high risk for bias. We believe that greater transparency and more complete reporting in studies of diagnostic test results should be mandated by peer-reviewed journals. The available literature suggests that several synovial fluid-based tests perform well for diagnosing chronic PJI and their use is recommended in the work-up of any suspected case of chronic PJI. LEVEL OF EVIDENCE: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Dew-induced transpiration suppression impacts the water and isotope balances of Colocasia leaves.

Foliar uptake of water from the surface of leaves is common when rainfall is scarce and non-meteoric water such as dew or fog is more abundant. However, many species in more mesic environments have hydrophobic leaves that do not allow the plant to uptake water. Unlike foliar uptake, all species can benefit from dew- or fog-induced transpiration suppression, but despite its ubiquity, transpiration suppression has so far never been quantified. Here, we investigate the effect of dew-induced transpiration suppression on the water balance and the isotope composition of leaves via a series of experiments. Characteristically, hydrophobic leaves of a tropical plant, Colocasia esculenta, are misted with isotopically enriched water to reproduce dew deposition. This species does not uptake water from the surface of its leaves. We measure leaf water isotopes and water potential and find that misted leaves exhibit a higher water potential and a more depleted water isotope composition than dry leaves, suggesting a ∼ 30% decrease in transpiration rate compared to control leaves. We propose three possible mechanisms governing the interaction of water droplets with leaf energy balance: increase in albedo from the presence of dew droplets, decrease in leaf temperature from the evaporation of dew, and local decrease in vapor pressure deficit. Comparing previous studies on foliar uptake to our results, we conclude that transpiration suppression has an effect of similar amplitude, yet opposite sign to foliar uptake on leaf water isotopes.

Measurement of Gross Photosynthesis, Respiration in the Light, and Mesophyll Conductance Using H218O Labeling.

A fundamental challenge in plant physiology is independently determining the rates of gross O2 production by photosynthesis and O2 consumption by respiration, photorespiration, and other processes. Previous studies on isolated chloroplasts or leaves have separately constrained net and gross O2 production (NOP and GOP, respectively) by labeling ambient O2 with 18O while leaf water was unlabeled. Here, we describe a method to accurately measure GOP and NOP of whole detached leaves in a cuvette as a routine gas-exchange measurement. The petiole is immersed in water enriched to a δ18O of ∼9,000‰, and leaf water is labeled through the transpiration stream. Photosynthesis transfers 18O from H2O to O2 GOP is calculated from the increase in δ18O of O2 as air passes through the cuvette. NOP is determined from the increase in O2/N2 Both terms are measured by isotope ratio mass spectrometry. CO2 assimilation and other standard gas-exchange parameters also were measured. Reproducible measurements are made on a single leaf for more than 15 h. We used this method to measure the light response curve of NOP and GOP in French bean (Phaseolus vulgaris) at 21% and 2% O2 We then used these data to examine the O2/CO2 ratio of net photosynthesis, the light response curve of mesophyll conductance, and the apparent inhibition of respiration in the light (Kok effect) at both oxygen levels. The results are discussed in the context of evaluating the technique as a tool to study and understand leaf physiological traits.

Phosphorus deficiency alters scaling relationships between leaf gas exchange and associated traits in a wide range of contrasting Eucalyptus species.

Phosphorus (P) limitation is known to have substantial impacts on leaf metabolism. However, uncertainty remains around whether P deficiency alters scaling functions linking leaf metabolism to associated traits. We investigated the effect of P deficiency on leaf gas exchange and related leaf traits in 17 contrasting Eucalyptus species that exhibit inherent differences in leaf traits. Saplings were grown under controlled-environment conditions in a glasshouse, where they were subjected to minus and plus P treatments for 15 weeks. P deficiency decreased P concentrations and increased leaf mass per area (LMA) of newly-developed leaves. Rates of photosynthesis (A) and respiration (R) were also reduced in P-deficient plants compared with P-fertilised plants. By contrast, P deficiency had little effect on the temperature sensitivity of R. Irrespective of P treatment, on a log-log basis A and R scaled positively with increasing leaf nitrogen concentration [N] and negatively with increasing LMA. Although P deficiency had limited impact on A-R-LMA relationships, rates of CO2 exchange per unit N were consistently lower in P-deficient plants. Our results highlight the importance of P supply for leaf carbon metabolism and show how P deficiencies (i.e. when excluding confounding genotypic and environmental effects) can have a direct effect on commonly used leaf trait scaling relationships.

Leaf day respiration: low CO2 flux but high significance for metabolism and carbon balance.

Contents 986 I. 987 II. 987 III. 988 IV. 991 V. 992 VI. 995 VII. 997 VIII. 998 References 998 SUMMARY: It has been 75 yr since leaf respiratory metabolism in the light (day respiration) was identified as a low-flux metabolic pathway that accompanies photosynthesis. In principle, it provides carbon backbones for nitrogen assimilation and evolves CO2 and thus impacts on plant carbon and nitrogen balances. However, for a long time, uncertainties have remained as to whether techniques used to measure day respiratory efflux were valid and whether day respiration responded to environmental gaseous conditions. In the past few years, significant advances have been made using carbon isotopes, 'omics' analyses and surveys of respiration rates in mesocosms or ecosystems. There is substantial evidence that day respiration should be viewed as a highly dynamic metabolic pathway that interacts with photosynthesis and photorespiration and responds to atmospheric CO2 mole fraction. The view of leaf day respiration as a constant and/or negligible parameter of net carbon exchange is now outdated and it should now be regarded as a central actor of plant carbon-use efficiency.

Leaf water 18 O and 2 H maps show directional enrichment discrepancy in Colocasia esculenta.

Spatial patterns of leaf water isotopes are challenging to predict because of the intricate link between vein and lamina water. Many models have attempted to predict these patterns, but to date, most have focused on monocots with parallel veins. These provide a simple system to study, but do not represent the majority of plant species. Here, a new protocol is developed using a Picarro induction module coupled to a cavity ringdown spectrometer to obtain maps of the leaf water isotopes (18 O and 2 H). The technique is applied to Colocasia esculenta leaves. The results are compared with isotope ratio mass spectrometry. In C. esculenta, a large enrichment in the radial direction is observed, but not in the longitudinal direction. The string-of-lakes model fails to predict the observed patterns, while the Farquhar-Gan model is more successful, especially when enrichment is accounted for along the radial direction. Our results show that reticulate-veined leaves experience a larger enrichment along the axis of the secondary veins than along the midrib. We hypothesize that this is due to the lower major/minor vein ratio that leads to longer pathways between major veins and sites of evaporation.

Global variability in leaf respiration in relation to climate, plant functional types and leaf traits.

Leaf dark respiration (Rdark ) is an important yet poorly quantified component of the global carbon cycle. Given this, we analyzed a new global database of Rdark and associated leaf traits. Data for 899 species were compiled from 100 sites (from the Arctic to the tropics). Several woody and nonwoody plant functional types (PFTs) were represented. Mixed-effects models were used to disentangle sources of variation in Rdark . Area-based Rdark at the prevailing average daily growth temperature (T) of each site increased only twofold from the Arctic to the tropics, despite a 20°C increase in growing T (8-28°C). By contrast, Rdark at a standard T (25°C, Rdark (25) ) was threefold higher in the Arctic than in the tropics, and twofold higher at arid than at mesic sites. Species and PFTs at cold sites exhibited higher Rdark (25) at a given photosynthetic capacity (Vcmax (25) ) or leaf nitrogen concentration ([N]) than species at warmer sites. Rdark (25) values at any given Vcmax (25) or [N] were higher in herbs than in woody plants. The results highlight variation in Rdark among species and across global gradients in T and aridity. In addition to their ecological significance, the results provide a framework for improving representation of Rdark in terrestrial biosphere models (TBMs) and associated land-surface components of Earth system models (ESMs).

Drought increases heat tolerance of leaf respiration in Eucalyptus globulus saplings grown under both ambient and elevated atmospheric [CO2] and temperature.

Climate change is resulting in increasing atmospheric [CO2], rising growth temperature (T), and greater frequency/severity of drought, with each factor having the potential to alter the respiratory metabolism of leaves. Here, the effects of elevated atmospheric [CO2], sustained warming, and drought on leaf dark respiration (R(dark)), and the short-term T response of R(dark) were examined in Eucalyptus globulus. Comparisons were made using seedlings grown under different [CO2], T, and drought treatments. Using high resolution T-response curves of R(dark) measured over the 15-65 °C range, it was found that elevated [CO2], elevated growth T, and drought had little effect on rates of R(dark) measured at T <35 °C and that there was no interactive effect of [CO2], growth T, and drought on T response of R(dark). However, drought increased R(dark) at high leaf T typical of heatwave events (35-45 °C), and increased the measuring T at which maximal rates of R(dark) occurred (Tmax) by 8 °C (from 52 °C in well-watered plants to 60 °C in drought-treated plants). Leaf starch and soluble sugars decreased under drought and elevated growth T, respectively, but no effect was found under elevated [CO2]. Elevated [CO2] increased the Q 10 of R(dark) (i.e. proportional rise in R(dark) per 10 °C) over the 15-35 °C range, while drought increased Q 10 values between 35 °C and 45 °C. Collectively, the study highlights the dynamic nature of the T dependence of R dark in plants experiencing future climate change scenarios, particularly with respect to drought and elevated [CO2].

A new anaplerotic respiratory pathway involving lysine biosynthesis in isocitrate dehydrogenase-deficient Arabidopsis mutants.

The cornerstone of carbon (C) and nitrogen (N) metabolic interactions - respiration - is presently not well understood in plant cells: the source of the key intermediate 2-oxoglutarate (2OG), to which reduced N is combined to yield glutamate and glutamine, remains somewhat unclear. We took advantage of combined mutations of NAD- and NADP-dependent isocitrate dehydrogenase activity and investigated the associated metabolic effects in Arabidopsis leaves (the major site of N assimilation in this genus), using metabolomics and (13)C-labelling techniques. We show that a substantial reduction in leaf isocitrate dehydrogenase activity did not lead to changes in the respiration efflux rate but respiratory metabolism was reorchestrated: 2OG production was supplemented by a metabolic bypass involving both lysine synthesis and degradation. Although the recycling of lysine has long been considered important in sustaining respiration, we show here that lysine neosynthesis itself participates in an alternative respiratory pathway. Lys metabolism thus contributes to explaining the metabolic flexibility of plant leaves and the effect (or the lack thereof) of respiratory mutations.

Metabolic origin of δ15 N values in nitrogenous compounds from Brassica napus L. leaves.

Nitrogen isotope composition (δ(15) N) in plant organic matter is currently used as a natural tracer of nitrogen acquisition efficiency. However, the δ(15) N value of whole leaf material does not properly reflect the way in which N is assimilated because isotope fractionations along metabolic reactions may cause substantial differences among leaf compounds. In other words, any change in metabolic composition or allocation pattern may cause undesirable variability in leaf δ(15) N. Here, we investigated the δ(15) N in different leaf fractions and individual metabolites from rapeseed (Brassica napus) leaves. We show that there were substantial differences in δ(15) N between nitrogenous compounds (up to 30‰) and the content in ((15) N enriched) nitrate had a clear influence on leaf δ(15) N. Using a simple steady-state model of day metabolism, we suggest that the δ(15) N value in major amino acids was mostly explained by isotope fractionation associated with isotope effects on enzyme-catalysed reactions in primary nitrogen metabolism. δ(15) N values were further influenced by light versus dark conditions and the probable occurrence of alternative biosynthetic pathways. We conclude that both biochemical pathways (that fractionate between isotopes) and nitrogen sources (used for amino acid production) should be considered when interpreting the δ(15) N value of leaf nitrogenous compounds.

In folio isotopic tracing demonstrates that nitrogen assimilation into glutamate is mostly independent from current CO2 assimilation in illuminated leaves of Brassica napus.

*Nitrogen assimilation in leaves requires primary NH(2) acceptors that, in turn, originate from primary carbon metabolism. Respiratory metabolism is believed to provide such acceptors (such as 2-oxoglutarate), so that day respiration is commonly seen as a cornerstone for nitrogen assimilation into glutamate in illuminated leaves. However, both glycolysis and day respiratory CO(2) evolution are known to be inhibited by light, thereby compromising the input of recent photosynthetic carbon for glutamate production. *In this study, we carried out isotopic labelling experiments with (13)CO(2) and (15)N-ammonium nitrate on detached leaves of rapeseed (Brassica napus), and performed (13)C- and (15)N-nuclear magnetic resonance analyses. *Our results indicated that the production of (13)C-glutamate and (13)C-glutamine under a (13)CO(2) atmosphere was very weak, whereas (13)C-glutamate and (13)C-glutamine appeared in both the subsequent dark period and the next light period under a (12)CO(2) atmosphere. Consistently, the analysis of heteronuclear ((13)C-(15)N) interactions within molecules indicated that most (15)N-glutamate and (15)N-glutamine molecules were not (13)C labelled after (13)C/(15)N double labelling. That is, recent carbon atoms (i.e. (13)C) were hardly incorporated into glutamate, but new glutamate molecules were synthesized, as evidenced by (15)N incorporation. *We conclude that the remobilization of night-stored molecules plays a significant role in providing 2-oxoglutarate for glutamate synthesis in illuminated rapeseed leaves, and therefore the natural day : night cycle seems critical for nitrogen assimilation.

In folio respiratory fluxomics revealed by 13C isotopic labeling and H/D isotope effects highlight the noncyclic nature of the tricarboxylic acid "cycle" in illuminated leaves.

While the possible importance of the tricarboxylic acid (TCA) cycle reactions for leaf photosynthesis operation has been recognized, many uncertainties remain on whether TCA cycle biochemistry is similar in the light compared with the dark. It is widely accepted that leaf day respiration and the metabolic commitment to TCA decarboxylation are down-regulated in illuminated leaves. However, the metabolic basis (i.e. the limiting steps involved in such a down-regulation) is not well known. Here, we investigated the in vivo metabolic fluxes of individual reactions of the TCA cycle by developing two isotopic methods, (13)C tracing and fluxomics and the use of H/D isotope effects, with Xanthium strumarium leaves. We provide evidence that the TCA "cycle" does not work in the forward direction like a proper cycle but, rather, operates in both the reverse and forward directions to produce fumarate and glutamate, respectively. Such a functional division of the cycle plausibly reflects the compromise between two contrasted forces: (1) the feedback inhibition by NADH and ATP on TCA enzymes in the light, and (2) the need to provide pH-buffering organic acids and carbon skeletons for nitrate absorption and assimilation.

Controle de gestão hospitalar / Hospital management control

Apresenta aos responsßveis pela administração hospitalar, uma proposta de princípios de administração de serviço público, direção, objetivos e um sistema de regulamentação permanente de decisões denominado controle de administração. Define centros de responsabilidade no hospital; e propõe a difusão de informações internas, o estabelecimento de métodos orcamentßrios, a participação dos médicos na administração, os métodos de mensuração e avaliação dos resultados quantitativos e uma abordagem das apreciações qualitativas das prestações de serviços