Modifications of Grapevine Berry Composition Induced by Main Viral and Fungal Pathogens in a Climate Change Scenario

The grapevine is subject to high number of fungal and viral diseases, which are responsible for important economic losses in the global wine sector every year. These pathogens deteriorate grapevine berry quality either directly via the modulation of fruit metabolic pathways and the production of endogenous compounds associated with bad taste and/or flavor, or indirectly via their impact on vine physiology. The most common and devastating fungal diseases in viticulture are gray mold, downy mildew (DM), and powdery mildew (PM), caused, respectively by Botrytis cinerea, Plasmopara viticola, and Erysiphe necator. Whereas B. cinerea mainly infects and deteriorates the ripening fruit directly, deteriorations by DM and PM are mostly indirect via a reduction of photosynthetic leaf area. Nevertheless, mildews can also infect berries at certain developmental stages and directly alter fruit quality via the biosynthesis of unpleasant flavor compounds that impair ultimate wine quality. The grapevine is furthermore host of a wide range of viruses that reduce vine longevity, productivity and berry quality in different ways. The most widespread virus-related diseases, that are known nowadays, are Grapevine Leafroll Disease (GLRD), Grapevine Fanleaf Disease (GFLD), and the more recently characterized grapevine red blotch disease (GRBD). Future climatic conditions are creating a more favorable environment for the proliferation of most virus-insect vectors, so the spread of virus-related diseases is expected to increase in most wine-growing regions. However, the impact of climate change on the evolution of fungal disease pressure will be variable and depending on region and pathogen, with mildews remaining certainly the major phytosanitary threat in most regions because their development rate is to a large extent temperature-driven. This paper aims to provide a review of published literature on most important grapevine fungal and viral pathogens and their impact on grape berry physiology and quality. Our overview of the published literature highlights gaps in our understanding of plant-pathogen interactions, which are valuable for conceiving future research programs dealing with the different pathogens and their impacts on grapevine berry quality and metabolism.

Gluconeogenesis in Plants: A Key Interface between Organic Acid/Amino Acid/Lipid and Sugar Metabolism

Gluconeogenesis is a key interface between organic acid/amino acid/lipid and sugar metabolism. The aims of this article are four-fold. First, to provide a concise overview of plant gluconeogenesis. Second, to emphasise the widespread occurrence of gluconeogenesis and its utilisation in diverse processes. Third, to stress the importance of the vacuolar storage and release of Krebs cycle acids/nitrogenous compounds, and of the role of gluconeogenesis and malic enzyme in this process. Fourth, to outline the contribution of fine control of enzyme activity to the coordinate-regulation of gluconeogenesis and malate metabolism, and the importance of cytosolic pH in this.

Sucrose Metabolism and Transport in Grapevines, with Emphasis on Berries and Leaves, and Insights Gained from a Cross-Species Comparison

In grapevines, as in other plants, sucrose and its constituents glucose and fructose are fundamentally important and carry out a multitude of roles. The aims of this review are three-fold. First, to provide a summary of the metabolism and transport of sucrose in grapevines, together with new insights and interpretations. Second, to stress the importance of considering the compartmentation of metabolism. Third, to outline the key role of acid invertase in osmoregulation associated with sucrose metabolism and transport in plants.

Sugar Metabolism in Stone Fruit: Source-Sink Relationships and Environmental and Agronomical Effects

The partitioning of assimilates in fruits, which are economically important sink organs, is ruled by different physiological processes and affected by both environmental and agronomical factors. The bulk of the water and solutes, required for growth, is imported into fruits and seeds through xylem and phloem. In the stone fruits, five vascular bundles enter the base of the fruit, then dividing to supply either the flesh or the seed. The main sugars accumulated in stone fruits include fructose, glucose, and sucrose, along with other minor saccharides. The mechanisms of phloem loading in these fruit species have not been fully elucidated yet, but the available data hint either an apoplastic or a symplastic type or possibly a combination of both, depending on the species and the sugar considered. Similarly, phloem unloading mechanisms, elucidated for a small number of species, depend on genotype and developmental stage. Remarkably, key enzymes and transporters involved in the main sugars-conversion and transport pathways have received considerable attention. In stone fruit trees, the presence of an elevated number of fruits alters the source-sink balance, with a consequent intensification of competition among them and between vegetative and reproductive growth. The main environmental factors affecting this balance and the agronomical/artificial manipulations of source-sink relationships to achieve adequate fruit production and quality are reviewed.

Non-structural Carbohydrate Metabolism in the Flesh of Stone Fruits of the Genus Prunus (Rosaceae) - A Review

Non-structural carbohydrates are abundant constituents of the ripe flesh of all stone fruits. The bulk of their content comprises sucrose, glucose, fructose and sorbitol. However, the abundance of each of these carbohydrates in the flesh differs between species, and also with its stage of development. In this article the import, subcellular compartmentation, contents, metabolism and functions of non-structural carbohydrates in the flesh of commercially cultivated stone fruits of the family Rosaceae are reviewed.

Stone Fruit as Biofactories of Phytochemicals With Potential Roles in Human Nutrition and Health

Phytochemicals or secondary metabolites present in fruit are key components contributing to sensory attributes like aroma, taste, and color. In addition, these compounds improve human nutrition and health. Stone fruits are an important source of an array of secondary metabolites that may reduce the risk of different diseases. The first part of this review is dedicated to the description of the main secondary organic compounds found in plants which include (a) phenolic compounds, (b) terpenoids/isoprenoids, and (c) nitrogen or sulfur containing compounds, and their principal biosynthetic pathways and their regulation in stone fruit. Then, the type and levels of bioactive compounds in different stone fruits of the Rosaceae family such as peach (Prunus persica), plum (P. domestica, P. salicina and P. cerasifera), sweet cherries (P. avium), almond kernels (P. dulcis, syn. P. amygdalus), and apricot (P. armeniaca) are presented. The last part of this review encompasses pre- and postharvest treatments affecting the phytochemical composition in stone fruit. Appropriate management of these factors during pre- and postharvest handling, along with further characterization of phytochemicals and the regulation of their synthesis in different cultivars, could help to increase the levels of these compounds, leading to the future improvement of stone fruit not only to enhance organoleptic characteristics but also to benefit human health.

Metabolism of Stone Fruits: Reciprocal Contribution Between Primary Metabolism and Cell Wall

Cell wall turnover and modification in its composition are key factors during stone fruit development and patterning. Changes in cell wall disassembly and reassembly are essential for fruit growth and ripening. Modifications in cell wall composition, resulting in the formation of secondary cell walls, are necessary for producing the most distinctive trait of drupes: the lignified endocarp. The contribution of primary metabolism to cell wall synthesis has been investigated in detail, while the knowledge on the contribution of the cell wall to primary metabolites and related processes is still fragmented. In this review, starting from peculiarities of cell wall of drupes cells (in mesocarp and endocarp layers), we discuss the structure and composition of cell wall, processes related to its modification and contribution to the synthesis of primary metabolites. In particular, our attention has been focused on the ascorbate synthesis cell wall-related and on the potential role of cyanogenic compounds in the deposition of the secondary cell wall.

Stone Fruits: Growth and Nitrogen and Organic Acid Metabolism in the Fruits and Seeds-A Review

Stone fruits of the Rosaceae family consist of several distinct parts, and these include the flesh, woody endocarp, and seed. To understand the metabolism of these fruits, it is necessary to have knowledge of both their structure and growth characteristics. The nitrogen metabolism of the different tissues of stone fruits is interlinked. For example, there is an import and storage of nitrogenous compounds in the endocarp that are then exported to the seed. Moreover, there are links between the metabolism of nitrogen and that of malic/citric acids. In this article, the structure and growth characteristics, together with the import/export, contents, metabolism, and functions of nitrogenous compounds and organic acids in the different parts of stone fruits and their seeds are reviewed.

Gluconeogenesis and nitrogen metabolism in maize

Two pathways can be used by gluconeogenesis in plants: one employs phosphoenolpyruvate carboxykinase (PEPCK) and the other pyruvate orthophosphate dikinase (PPDK). The occurrence-location of these enzymes was determined in developing kernels of maize. PPDK was much more abundant than PEPCK in extracts of whole kernels. However, their location within the kernel was different. PPDK was particularly abundant in the peripheral endosperm (in which alanine is abundant), whereas PEPCK was localised in the pedicel and basal endosperm transfer cells (where asparagine is metabolised). The abundance of these enzymes was also determined in maize roots where there was a massive increase in abundance of PEPCK and a small increase in abundance of PPDK when they were fed ammonium; PEPCK was located in the pericycle and various cell types associated with the vasculature. On the other hand, there was a large increase in abundance of PPDK in roots subjected to anoxia (which induces an accumulation of alanine), whereas the abundance of PEPCK was decreased. These results show: firstly, that gluconeogenesis can potentially occur in many different tissues of maize. Secondly, within one organ PPDK can be abundant in some tissues and PEPCK in others. Thirdly, the abundance of PPDK and PEPCK is often associated with the metabolism of certain nitrogenous compounds and can be dramatically altered by factors related to nitrogen metabolism. In maize roots and developing kernels PPDK was associated with alanine metabolism. By contrast, the presence of PEPCK in maize roots and kernels was associated with either ammonium or asparagine metabolism. We propose that gluconeogenesis is often a component of a widespread mechanism that is used in coordinating the import/mobilisation of nitrogenous compounds with their utilisation. Further, potentially component of this mechanism may have provided building blocks that were used in the evolution of processes such as C₄ photosynthesis, Crassulacean acid metabolism, stomatal metabolism and the biochemical pH stat.

Late summer photosynthesis and storage carbohydrates in walnut (Juglans regia L.): Feed-back and feed-forward effects

The effect of late summer - autumn limitation of phloem export on growth, photosynthesis and storage carbohydrate accumulation, was evaluated in walnut (Juglans regia L.). This was done by girdling current years shoots, with either all or with only a third of the leaves left in place. Nineteen days after girdling, photosynthesis was greatly reduced and after 46 days, it was about 70% lower in both girdling treatments compared to the control (ungirdled shoots). This reduction is consistent with a feed-back effect of an increased carbohydrate content of the leaves. At the end of the experiment (46 days after girdling), the radial growth of girdled shoots was increased at their base but not at their apical part compared to the control. Girdling increased the accumulation of sucrose in the bark at the base of the shoot and of starch in the bark and in the wood of the shoot apical part. The activity of ADP-glucose pyrophosphorylase in wood increased in the apical part of girdled shoots. The results suggest that a high availability of carbohydrates elicits a feed-forward action on the shoot sink size and activity (radial growth and storage carbohydrate accumulation). Further, for the first time in tree wood we found an increased total activity of AGP induced by an increased assimilate availability. Moreover, the results indicated that, in late summer - autumn, CO₂ uptake by leaves of the deciduous tree walnut is strongly dependent on export of photosynthates from the crown. Therefore, carbon uptake in this period depends largely on the availability of effective storage sinks where newly produced assimilates can be accumulated.

Peach leaf curl disease shifts sugar metabolism in severely infected leaves from source to sink

Peach leaf curl is a disease that affects the leaves of peach trees, and in severe cases all of the leaf can be similarly affected. This study investigated some effects of this disease on the metabolism of peach leaves in which all parts of the leaf were infected. These diseased leaves contained very little chlorophyll and performed little or no photosynthesis. Compared to uninfected leaves, diseased leaves possessed higher contents of fructose and especially glucose, but lowered contents of sucrose, sorbitol and especially starch. The activities of soluble acid invertase, neutral invertase, sorbitol dehydrogenase and sucrose synthase were all higher in diseased leaves, whereas, those of aldose-6-phosphate reductase and sucrose phosphate synthase were lower. The activities of hexokinase and fructokinase were little changed. In addition, immunblots showed that the contents of Rubisco and ADP-glucose phosphorylase were reduced in diseased leaves, whereas, the content of phosphoenolpyruvate carboxylase was increased. The results show that certain aspects of the metabolism of diseased leaves are similar to immature sink leaves. That is photosynthetic function is reduced, the leaf imports rather than exports sugars, and the contents of non-structural carbohydrates and enzymes involved in their metabolism are similar to sink leaves. Further, the effects of peach leaf curl on the metabolism of peach leaves are comparable to the effects of some other diseases on the metabolism of photosynthetic organs of other plant species.

Phosphorylation of phosphoenolpyruvate carboxykinase (PEPCK) and phosphoenolpyruvate carboxylase (PEPC) in the flesh of fruits

This study determined whether phosphoenolpyruvate carboxykinase (PEPCK) and phosphoenolpyruvate carboxylase (PEPC) are phosphorylated in the flesh of a range of fruits. This was done by incubating fruit flesh with ³²P[P] (where ³²P[P] = ³²PO₄^3-), then PEPCK and PEPC were immunoprecipitated from extracts using specific antisera. The incorporation of ³²P[P] into these enzymes was then determined by autoradiography of SDS-PAGE gels. Both enzymes were subject to phosphorylation in vivo in the flesh of grape, tomato, cherry and plum. PEPCK was also subject to phosphorylation in vivo in developing grape seeds. Proteolytic cleavage of PEPCK showed that it was phosphorylated at a site(s) located on its N-terminal extension. Potentially phosphorylation of these enzymes could contribute to the coordinate regulation of their activities in the flesh of fruits and in developing seeds.

Phosphoenolpyruvate carboxykinase, pyruvate orthophosphate dikinase and isocitrate lyase in both tomato fruits and leaves, and in the flesh of peach and some other fruits

In this study the occurrence of a number of enzymes involved in gluconeogenesis was investigated in both tomato fruits and leaves during their development and senescence and in some other fruits. The enzymes studied were phosphoenolpyruvate carboxykinase (PEPCK), pyruvate orthophosphate dikinase (PPDK) and glyoxysomal isocitrate lyase (ICL). PPDK was detected in the ripe flesh of tomato, and much smaller amounts were detected in the flesh of both peach and pepper, whereas it was not detected (not present or at very low abundance) in the other fruits which were investigated (apricot, aubergine, blackberry, blueberry, cherry, grape, plum, raspberry and red current). By contrast PEPCK was present in the flesh of all the fruits investigated. Very small amounts of ICL were detected in ripe tomato flesh. PEPCK was present in the skin, flesh, locular gel and columella of tomato fruit, and in these its abundance increased greatly during ripening. PPDK showed a similar distribution, however, its abundance did not increase during ripening. PEPCK was not detected in tomato leaves at any stage of their development or senescence. The content of PPDK g(-1) fresh weight (FW) increased in tomato leaves as they matured, however, it declined during their senescence. In tomato leaves the content of ICL g(-1) FW increased until the mid-stage of development, then decreased as the leaf matured, and then increased during the latter stages of senescence. In the flesh of tomato fruits the contents of PPDK and PEPCK g(-1) FW decreased during senescence. The results suggest that in fruits other than tomato the bulk of any gluconeogenic flux proceeds via PEPCK, whereas in tomato both PEPCK and PPDK could potentially be utilised. Further, the results indicate that the conversion of pyruvate/acetyl-CoA to malate by the glyoxylate cycle, for which ICL is necessary, is not a major pathway utilised by gluconeogenesis in fruits under normal conditions of growth. Finally, the results contribute to our understanding of the role of several enzymes in the senescence of both leaves and fruits.

The contribution of stored malate and citrate to the substrate requirements of metabolism of ripening peach (Prunus persica L. Batsch) flesh is negligible. Implications for the occurrence of phosphoenolpyruvate carboxykinase and gluconeogenesis

The first aim of this study was to determine the contribution of stored malate and citrate to the substrate requirements of metabolism in the ripening flesh of the peach (Prunus persica L. Batsch) cultivar Adriatica. In the flesh, stored malate accumulated before ripening could contribute little or nothing to the net substrate requirements of metabolism. This was because there was synthesis and not dissimilation of malate throughout ripening. Stored citrate could potentially contribute a very small amount (about 5.8%) of the substrate required by metabolism when the whole ripening period was considered, and a maximum of about 7.5% over the latter part of ripening. The second aim of this study was to investigate why phosphoenolpyruvate carboxykinase (PEPCK) an enzyme utilised in gluconeogenesis from malate and citrate is present in peach flesh. The occurrence and localisation of enzymes utilised in the metabolism of malate, citrate and amino acids were determined in peach flesh throughout its development. Phosphoenolpyruvate carboxylase (essential for the synthesis of malate and citrate) was present in the same cells and at the same time as PEPCK and NADP-malic enzyme (both utilised in the dissimilation of malate and citrate). A hypothesis is presented to explain the presence of these enzymes and to account for the likely occurrence of gluconeogenesis.

Phosphoenolpyruvate carboxykinase and gluconeogenesis in grape pericarp

Glycolysis from sugars is necessary at all stages of development of grape pericarp, and this raises the question as to why gluconeogenesis from malate occurs. Phosphoenolpyruvate carboxykinase (PEPCK) is required for gluconeogenesis in grape pericarp. In this study we determined the abundance of PEPCK protein and activity in different parts of grape pericarp during its development. Both PEPCK protein and activity were present throughout development, however, in both the skin and the flesh their abundance increased greatly at the start of ripening. This coincided with the onset of the decrease in the malate content of the berry. The location of PEPCK in the pericarp at different stages of development was determined using both immunohistochemistry and dissection. We provide a possible explanation for the occurrence of gluconeogenesis in grape pericarp.

Occurrence of a number of enzymes involved in either gluconeogenesis or other processes in the pericarp of three cultivars of grape (Vitis vinifera L.) during development

It is uncertain whether the enzymes pyruvate orthophosphate dikinase (PPDK) or isocitrate lyase (ICL) are present in the pericarp of grape, in which they could function in gluconeogenesis. The occurrence of these and other enzymes was investigated in the pericarp of three cultivars of grape (Vitis vinifera L.). In particular, the abundance of the enzymes aldolase, glutamine synthase (GS), acid invertase, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), phosphoenolpyruvate carboxylase (PEPC), PPDK and ICL were determined during the development of the pericarp of the cultivars Cabernet Sauvignon, Chardonnay and Zibibbo. PPDK and ICL were not detected at any stage of development. Each of the other enzymes showed different changes in abundance during development. However, for a given enzyme its changes in abundance were similar in each cultivar. In the ripe pericarp of Cabernet Sauvignon, PEPC, cytosolic GS and aldolase were equally distributed between the vasculature and parenchyma cells of the flesh and skin. The absence or very low abundance of PPDK provides strong evidence that any gluconeogenesis from malate utilises phosphoenolpyruvate carboxykinase (PEPCK). The absence or very low abundance of ICL in the pericarp precludes any gluconeogenesis from ethanol.

Is stored malate the quantitatively most important substrate utilised by respiration and ethanolic fermentation in grape berry pericarp during ripening?

A widely held view is that in grape pericarp glycolysis is inhibited during ripening, and that stored malate rather than sugars become the major substrate for respiration. In this study we determined what contribution stored malate could make to the substrate requirements of respiration and ethanolic fermentation in the pericarp of Cabernet Sauvignon berries during ripening. At a number of time points through development the amount of malate in the pericarp was measured. The change in malate content between each time point was then calculated, having first allowed for dilution arising from expansion of the fruit. The amount of CO2 that was released by the berry in the interval between each pair of time points was measured. It was found that the contribution that stored malate could make to the substrate requirements of respiration and ethanolic fermentation of grape pericarp was dependent on the stage of ripening. At the beginning of ripening stored malate could provide a greater proportion of substrate than later in ripening, and during the latter its contribution was relatively low. Therefore, stored malate was not the quantitatively most important substrate utilised by respiration and ethanolic fermentation in the pericarp of grape berries during most of ripening. It is likely that sugars provide the bulk of the deficit in substrate. Further, the increase in the respiratory quotient during most of ripening does not arise from the use of malate as main respiratory substrate.

Development and metabolism of the fruit and seed of the Japanese plum Ozark premier (Rosaceae)

The growth characteristics of some plums and their component parts have been previously studied, as have some aspects of their developmental anatomy and composition. However, little is known about either their metabolism or about the interactions between the metabolism of their component parts. In this study we investigated these aspects in the Japanese plum Ozark Premier. Throughout fruit and seed development, changes in sugar and organic acid contents, protein composition and abundance of selected enzymes were determined. In the stone, there was a transient accumulation of vegetative storage proteins. These were subsequently mobilized and this coincided with the onset of the lignification of the stone and the start of storage protein accumulation in the seed. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) was present in the seeds, even though they lacked chlorophyll, and its presence may be related to limited gas exchange. In the flesh of some fruits, phosphoenolpyruvate carboxykinase (PEPCK) and NADP malic enzyme (NADP-ME) are thought to function in the dissimilation of malate and/or citrate during ripening. However, PEPCK and NADP-ME were present in plum flesh for most of its development, although there was no net dissimilation of malate until the latter stages of ripening. There is an interaction between the developing seed and endocarp with respect to the utilization of imported sugars and amino acids. An hypothesis is presented to account for the presence of PEPCK and NADP-ME enzyme in plum flesh when there was no net dissimilation of organic acids.

Phosphoenolpyruvate carboxykinase in cherry (Prunus avium L.) fruit during development

In this study the abundance and location of phosphoenolpyruvate carboxykinase (PEPCK) was determined in the flesh and skin of the sweet cherry (Prunus avium L.) cultivar Durone Nero II during development. PEPCK was not present in young fruit but appeared in both tissues as the fruit increased in size. In these there was no net dissimilation of malic acid, which accounts for the bulk of their organic acid contents when PEPCK was present. To assist in understanding the function of PEPCK, the abundance of a number of other enzymes was determined. These enzymes were aspartate aminotransferase (AspAT), glutamine synthetase (GS), phosphoenolpyruvate carboxylase (PEPC), pyruvate, orthophosphate dikinase (PPDK), and ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco). A potential role for PEPCK in the regulation of pH and the utilization of malate in gluconeogenesis in the flesh and skin of cherries is presented.

Metabolism of the seed and endocarp of cherry (Prunus avium L.) during development

In this study some aspects of organic and amino acid metabolism in cherry endocarp and seed were investigated during their development. The abundance and location of a number of enzymes involved in these processes were investigated. These enzymes were aspartate aminotransferase (AspAT; EC:2.6.1.1), glutamine synthetase (GS; EC:6.3.1.2), phosphoenolpyruvate carboxylase (PEPC; EC:4.1.1.31), phosphoenolpyruvate carboxykinase (PEPCK; EC:4.1.1.49), and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; EC:4.1.1.39). There was a transient and massive accumulation of vegetative storage proteins in the endocarp. These proteins were remobilised as the endocarp lignified and at the same time that proteins were accumulated in the seed. This raised the possibility that a proportion of imported amino acids were temporarily stored in the endocarp as protein, and that these were later utilised by the seed when it started to accumulate storage proteins. Rubisco was present in the embryo and integuments of the seed although no chlorophyll was present. This is the first time that Rubisco has been detected in non-green seeds. The maximum abundance of Rubisco in the seed coincided with the deposition of seed storage proteins. A possible function for Rubisco in cherry seed is discussed. PEPCK was located in the integuments and appeared when seed storage proteins were being accumulated. In the integuments and embryo AspAT, GS, PEPC and Rubisco also appeared, or greatly increased in abundance, when seed storage proteins were being deposited.

Coordinate regulation of phosphoenolpyruvate carboxylase and phosphoenolpyruvate carboxykinase by light and CO2 during C4 photosynthesis

The aim of this study was to investigate the relationship between the phosphorylation and activation states of phosphoenolpyruvate carboxykinase (PEPCK) and to investigate how the phosphorylation states of PEPCK and phosphoenolpyruvate carboxylase (PEPC) are coordinated in response to light intensity and CO(2) concentration during photosynthesis in leaves of the C(4) plant Guinea grass (Panicum maximum). There was a linear, reciprocal relationship between the phosphorylation state of PEPCK and its activation state, determined in a selective assay that distinguishes phosphorylated from nonphosphorylated forms of the enzyme. At high photon flux density and high CO(2) (750 microL L(-1)), PEPC was maximally phosphorylated and PEPCK maximally dephosphorylated within 1 h of illumination. The phosphorylation state of both enzymes did not saturate until high light intensities (about 1,400 micromol quanta m(-2) s(-1)) were reached. After illumination at lower light intensities and CO(2) concentrations, the overall change in phosphorylation state was smaller and it took longer for the change in phosphorylation state to occur. Phosphorylation states of PEPC and PEPCK showed a strikingly similar, but inverse, pattern in relation to changes in light and CO(2). The protein phosphatase inhibitor, okadaic acid, promoted the phosphorylation of both enzymes. The protein synthesis inhibitor, cycloheximide, blocked dark phosphorylation of PEPCK. The data show that PEPC and PEPCK phosphorylation states are closely coordinated in vivo, despite being located in the mesophyll and bundle sheath cells, respectively.

Phospho enol pyruvate Carboxykinase in Arabidopsis: Changes in Gene Expression, Protein and Activity during Vegetative and Reproductive Development

The aim of this work was to investigate the occurrence of phosphoenolpyruvate carboxykinase (PEPCK) in different tissues of Arabidopsis thaliana throughout its vegetative and reproductive growth. The A. thaliana genome contains two PEPCK genes (PCK1 and PCK2), and these are predicted to generate 73,404 and 72,891 Da protein products, respectively. Both genes were transcribed in a range of tissues; however, PCK1 mRNA appeared to be more abundant and was present in a wider range of tissues. PEPCK protein was present in flowers, fruit, developing seed, germinating seed, leaves, stems and roots. Two PEPCK polypeptides, of approximately 74 and approximately 73 kDa were detected by immunoblotting, and these may arise from PCK1 and PCK2, respectively. PEPCK was abundant in cotyledons during post-germinative growth, and this is consistent with its well established role in gluconeogenesis. PEPCK was also abundant in sink tissues, such as young leaves, in developing flowers, fruit and seed. Immunohistochemistry and in situ hybridization showed that PEPCK was present in the nectaries, stigma, endocarp of the fruit wall and in tissues involved in the transfer of assimilates to the developing ovules and seeds, such as the vasculature and seed coat. The potential functions of PEPCK in A. thaliana are discussed.

Phosphoenolpyruvate carboxykinase in developing pea seeds is associated with tissues involved in solute transport and is nitrogen-responsive

The aim of this work was to investigate the occurrence of phosphoenolpyruvate carboxykinase (PEPCK) in developing pea (Pisum sativum) seeds in relation to their nitrogen supply. PEPCK was present throughout development, with the peak of PEPCK protein and activity in the seed coat and cotyledons preceding protein accumulation in the cotyledons. It showed a different developmental pattern from enzymes involved in amino acid metabolism (phosphoenolpyruvate carboxylase, glutamine synthetase and glutamate dehydrogenase). Immunolocalization showed that PEPCK was present in parts of the developing seed that are involved in the transport and metabolism of assimilates. Early in development, it was associated with the inner integument of the ovule, the endospermic cytoplasm and the outer cells of the embryo. In the middle of development, around the peak of activity, PEPCK was abundant at the outer surface of the developing cotyledons, in the embryonic axis and in the vasculature of the seed coat. Later in development, PEPCK was associated with the embryonic leaf primordia and meristem and cortex of the radicle. PEPCK protein was strongly induced in vitro in the seed coat by nitrate, ammonium and asparagine, in the cotyledons by asparagine and in planta by the supply of nitrogen, which led to an increase in asparagine secretion by empty seed coats. It is suggested that PEPCK is involved in the metabolism of nitrogenous solutes in developing pea seeds.

Phosphoenolpyruvate carboxykinase and its potential role in the catabolism of organic acids in the flesh of soft fruit during ripening

Previous studies of grapes and tomatoes have shown that the abundance of phosphoenolpyruvate carboxykinase (PEPCK) increases in their flesh at the start of ripening, and that this coincides with a decrease in its citrate and/or malate content. Thus, PEPCK might function in the catabolism of organic acid anions during the ripening of these fruits. In the present study, the abundance of PEPCK was determined in the flesh of blueberries, raspberries, red currants, and strawberries at different stages of their development. In addition, changes in the amounts of citrate, malate, soluble sugars, isocitrate lyase, NADP-malic enzyme, phosphoenolpyruvate carboxylase, and pyruvate, orthophosphate dikinase in the flesh were determined. PEPCK was not detected in strawberry flesh, in which there was no dissimilation of malate or citrate. In the flesh of the other fruits, the abundance of PEPCK increased during ripening to an amount that was similar to that in grapes and tomatoes. In the flesh of blueberries and red currants, PEPCK was most abundant when there was dissimilation of malate. In the flesh of raspberries, PEPCK was most abundant when there was dissimilation of malate and citrate. These results are consistent with PEPCK playing a role in the dissimilation of citrate and/or malate in the flesh of these fruits during ripening. However, PEPCK was also present in the flesh of blueberries, raspberries, and red currants when there was no dissimilation of malate or citrate, and this raises the possibility that PEPCK might have additional functions. Dissection of blueberries provided evidence that both PEPCK and phosphoenolpyruvate carboxylase were present in the same cells, and possible functions for this are discussed.

Phosphoenolpyruvate carboxykinase in cucumber plants is increased both by ammonium and by acidification, and is present in the phloem

In cucumber ( Cucumis sativus L.), phosphoenolpyruvate carboxykinase (PEPCK) was shown by activity measurements and immunoblots to be present in leaves, stems, roots, flowers, fruit and seed. However, immunolocalisation showed that it was present only in certain cell types. PEPCK was present in the companion cells of the adaxial phloem of minor veins, the adaxial and abaxial phloem of larger veins, the internal and external phloem of vascular bundles in petioles and stems, the phloem in roots and the extra-fascicular phloem in leaves, cotyledons, petioles and stems. Immunohistochemical evidence suggests that both the extra-fascicular phloem and the adaxial phloem are involved in the transport of amino acids. In roots and stems, the abundance of PEPCK was greatly increased by watering plants with a solution of ammonium chloride at low, but not at high pH. PEPCK also increased in leaves, but not roots or stems, of seedlings grown in an atmosphere containing 5% CO(2), and in roots and stems of seedlings watered with butyric acid. All these treatments are known to lower the pH of plant cells. Amino acid metabolism in the phloem may produce an excess of carbon skeletons, pH perturbations and an imbalance in the production/utilisation of NADH. This raises the possibility that PEPCK may function in the conversion of these carbon skeletons to PEP, which, depending on the energy requirements of the phloem, is subsequently utilised by either gluconeogenesis or the Krebs cycle, which both consume protons.

Effects of phosphorylation on phosphoenolpyruvate carboxykinase from the C4 plant Guinea grass

In the C4 plant Guinea grass (Panicum maximum), phosphoenolpyruvate carboxykinase (PEPCK) is phosphorylated in darkened leaves and dephosphorylated in illuminated leaves. To determine whether the properties of phosphorylated and non-phosphorylated PEPCK were different, PEPCK was purified to homogeneity from both illuminated and darkened leaves. The final step of the purification procedure, gel filtration chromatography, further separated phosphorylated and non-phosphorylated forms. In the presence of a high ratio of ATP to ADP, the non-phosphorylated enzyme had a higher affinity for its substrates, oxaloacetate and phosphoenolpyruvate. The activity of the non-phosphorylated form was up to 6-fold higher when measured at low substrate concentrations. Comparison of proteoloytically cleaved PEPCK from Guinea grass, which lacked its N-terminal extension, from yeast (Saccharomyces cerevisiae), which does not possess an N-terminal extension, and from the C4 plant Urochloa panicoides, which possesses an N-terminal extension but is not subject to phosphorylation, revealed similar properties to the non-phosphorylated full-length form from Guinea grass. Assay of PEPCK activity in crude extracts of Guinea grass leaves, showed a large difference between illuminated and darkened leaves when measured in a selective assay (a low concentration of phosphoenolpyruvate and a high ratio of ATP to ADP), but there was no difference under assay conditions used to estimate maximum activity. Immunoblots of sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels showed no difference in the abundance of PEPCK protein in illuminated and darkened leaves. There were no light/dark differences in activity detected in maize (Zea mays) leaves, in which PEPCK is not subject to phosphorylation.

Phosphoenolpyruvate carboxykinase assayed at physiological concentrations of metal ions has a high affinity for CO2

The effect of Mn2+/Mg2+ concentration on the activity of intact, homogeneous phosphoenolpyruvate carboxykinase (PEPCK) from leaves of the C4 grass, Guinea grass (Panicum maximum), have been investigated. Assay conditions were optimized so that PEPCK activity could be measured at concentrations of Mn2+/Mg2+ similar to those found in the cytosol (low micromolar Mn2+ and millimolar Mg2+). PEPCK activity was totally dependent on Mn2+ and was activated at low micromolar concentrations of Mn2+ by millimolar concentrations of Mg2+. Therefore, at physiological concentrations of Mn2+, PEPCK has a requirement for Mg2+. Assay at physiological concentrations of Mn2+/Mg2+ led to a marked decrease in its affinity for ATP and a 13-fold increase in its affinity for CO2. The Km (CO2) was further decreased by assay at physiological ATP to ADP ratios, reaching values as low as 20 microM CO2, comparable with the Km (CO2) of ribulose 1,5-bisphosphate carboxylase-oxygenase. This means that PEPCK will catalyze a reversible reaction and that it could operate as a carboxylase in vivo, a feature that could be particularly important in algal CO2-concentrating systems.

Ripening-related occurrence of phosphoenolpyruvate carboxykinase in tomato fruit

Phosphoenolpyruvate carboxykinase (PEPCK) is present in ripening tomato fruits. A cDNA encoding PEPCK was identified from a PCR-based screen of a cDNA library from ripe tomato fruit. The sequence of the tomato PEPCK cDNA and a cloned portion of the genomic DNA shows that the complete cDNA sequence contains an open reading frame encoding a peptide of 662 amino acid residues in length and predicts a polypeptide with a molecular mass of 73.5 kDa, which corresponds to that detected by western blotting. Only one PEPCK gene was identified in the tomato genome. PEPCK is shown to be present in the pericarp of ripening tomato fruits by activity measurements, western blotting and mRNA analysis. PEPCK abundance and activity both increased during fruit ripening, from an undetectable amount in immature green fruit to a high amount in ripening fruit. PEPCK mRNA, protein and activity were also detected in germinating seeds and, in lower amounts, in roots and stems of tomato. The possible role of PEPCK in the pericarp of tomato fruit during ripening is discussed.

Clinical features and risk of recurrence among patients with vaginal intraepithelial neoplasia

OBJECTIVE

The best treatment modality and factors affecting recurrence among women with vaginal intraepithelial neoplasia (VAIN) are yet to be determined. The aims of the current study were to describe the clinical features, results of treatment, and factors affecting recurrence among patients with VAIN.

METHODS

We conducted a retrospective review of 121 women with VAIN after confirming the histologic diagnosis. Patient demographics, clinical features, and results of therapy were recorded. Factors affecting recurrence were assessed using the odds ratio and the 95% confidence intervals among patients who were followed up for 7 months or more and had at least one posttreatment Papanicolaou smear. Significant univariate odds ratios were assessed jointly in a multivariate model with a stratified analysis.

RESULTS

The mean age of the patients was 35.0 (+/-17), 41% of the patients smoked, 39% had a history of human papillomavirus infection, 27% had history of sexually transmitted diseases, 22% had history of surgery for cervical intraepithelial neoplasia (CIN), and 23% had total hysterectomy. The upper third of the vagina was the most common site of VAIN and 61% of the lesions were multifocal. Associated cervical and vulvar intraepithelial neoplasia (VIN) were present in 65 and 10%, respectively. Recurrences of VAIN and progression to invasive vaginal cancer occurred in 33 and 2%, respectively. Recurrences following partial vaginectomy, laser, and 5-fluorouracil were 0, 38, and 59%, respectively (P = 0.0001). Multifocality and method of treatment were significant independent predictors of VAIN recurrences (odds ratio 3.3, 95% CI 1.2, 9.2, P = 0.02, and 22.4, 95% CI 1.3, 393.6, P = 0.001, respectively), with no interaction, based on a stratified analysis.

CONCLUSIONS

VAIN occurs most often among women with CIN or VIN, commonly involves the upper third of the vagina, and is often multifocal. Partial vaginectomy provides the highest cure rate and multifocality is a risk factor for recurrence.

Does phosphoenolpyruvate carboxykinase have a role in both amino acid and carbohydrate metabolism?

Phosphoenolpyruvate carboxykinase (PEPCK) catalyses the reversible decarboxylation of oxaloacetate to yield phosphoenolpyruvate and CO2. The role of the enzyme in gluconeogenesis and anaplerotic reactions in a range of organisms is discussed, along with the important function in C4 and CAM photosynthesis in higher plants. In addition, new data are presented indicating that PEPCK may play a key role in amino acid metabolism. It is proposed that PEPCK is involved in the conversion of the carbon skeleton of asparagine/aspartate (oxaloacetate) to that of glutamate/glutamine (2-oxoglutarate). This metabolism is particularly important in the transport system, seeds and fruits of higher plants.

Preoperative differences between male and female patients with sleep apnea

OBJECTIVES/HYPOTHESIS

To evaluate the differences between female and male patients with obstructive sleep apnea syndrome (OSAS) in the preoperative period.

STUDY DESIGN

Nonrandomized cross-sectional study.

METHODS

An analysis of 686 patients (111 women and 575 men) with OSAS was completed. Multivariate modeling techniques were employed to correlate gender with the preoperative respiratory disturbance index (RDI), apnea index (AI), hypopnea index (HI), body mass index (BMI), age, and initial symptoms.

RESULTS

At presentation, the male patients were significantly younger and had a lower BMI and a higher RDI and AI than the female patients. For the entire OSAS population studied, the RDI increased as the BMI increased (correlation coefficient [r] = 0.35, P = <.001). For the female patients there was a weaker correlation (r = 0.21, P =.034), and in male patients there was a stronger correlation (r = 0.40, P <.001). For the entire population there was a negative correlation between age and RDI (r = -0.15, P <.001). In female patients there was a nonsignificant correlation (r = -0.09, P =.35), and in male patients the correlation was significant (r = -0.16, P <.001). There was no difference in the reporting of the number of symptoms based on gender (P =.355). Female patients noted headaches on awakening more commonly than male patients (P =.001), and male patients noted snoring (P =.014) and stopping breathing during sleep (P =.001) more often than female patients.

CONCLUSIONS

The analysis demonstrated that within a surgical population sample, gender differences exist. The findings of this series were as follows: 1) Apnea severity in women was less weight-dependent than in men; (2) in men there was a significant negative correlation between age and apnea severity; and (3) female and male patients reported the same number of signs or symptoms on presentation, although certain signs and symptoms were more commonly reported based on gender. Current clinical evaluation practices must take into account this gender disparity.

Using immunohistochemistry to study plant metabolism: the examples of its use in the localization of amino acids in plant tissues, and of phosphoenolpyruvate carboxykinase and its possible role in pH regulation

To understand many aspects of the metabolism of complex plant structures such as leaves, fruit and roots it is important to understand how metabolic processes are compartmentalized between tissues. The aim of this article is to show how immunohistochemistry, in conjunction with biochemical and physiological studies, is useful in understanding both the function of an enzyme in a tissue and metabolic processes occurring in plant tissues. This is illustrated by two examples. Firstly, the use of immunohistochemisty in the localization of amino acids in plant tissues is described. Secondly, the use of immunohistochemistry in understanding the function of an enzyme in a tissue and the metabolic processes occurring within the tissue is described. To illustrate this the example of phosophoenolpyruvate carboxykinase (PEPCK), an enzyme which is present in many plant tissues in which its function is unknown, is used. Evidence is provided that PEPCK may play a role in pH regulation in tissues active in the metabolism of nitrogen.

Are isocitrate lyase and phosphoenolpyruvate carboxykinase involved in gluconeogenesis during senescence of barley leaves and cucumber cotyledons?

The aim of this study was to investigate whether gluconeogenesis catalysed by phosphoenolpyruvate carboxykinase (PEPCK) occurs during leaf senescence. This was addressed by determining changes in the abundance and intercellular location of enzymes necessary for gluconeogenesis during the senescence of barley leaves and cucumber cotyledons. PEPCK was never present in barley leaves, despite the presence of large amounts of isocitrate lyase (ICL), a key enzyme of the glyoxylate cycle, and of its product, glyoxylate. Although PEPCK was present in non-senescent cucumber cotyledons, its abundance declined during senescence. Throughout senescence, PEPCK was only present in the trichomes and vasculature, whereas ICL was located in mesophyll cells. Pyruvate,Pi dikinase (PPDK) which, in concert with NAD(P)-malic enzyme, is also capable of catalysing gluconeogenesis, was present in non-senescent barley leaves and cucumber cotyledons, but in both plants its abundance decreased greatly during senescence. The abundance of ICL was greatly reduced in senescing detached barley leaves by either illumination or by co-incubation with sucrose, and greatly increased in darkened attached barley leaves. These results argue against the large-scale occurrence of gluconeogenesis during senescence catalysed either by PEPCK or PPDK. In cucumber cotyledons, PEPCK may play a role in metabolic processes linked to the export of amino acids, a role in which phosphoenolpyruvate carboxylase may also be involved. The amount of ICL was increased by starvation and during senescence may function in the conversion of lipids to organic acids, which are then utilised in the mobilisation of amino acids from leaf protein.

An immunohistochemical study of the compartmentation of metabolism during the development of grape (Vitis vinifera L.) berries

The compartmentation of key processes in sugar, organic acid and amino acid metabolism was studied during the development of the flesh and seeds of grape (Vitis vinifera L.) berries. Antibodies specific for enzymes involved in sugar (cell wall and vacuolar invertases, pyrophosphate: fructose 6-phosphate phosphotransferase, aldolase, NADP-glyceraldehyde-P dehydrogenase, cytosolic fructose 1,6-bisphosphatase), photosynthesis (Rubisco, fructose 1,6-bisphosphatase, sedoheptulose 1,7-bisphosphatase), amino acid metabolism (cytosolic and mitochondrial aspartate aminotransferases, alanine aminotransferase, glutamate dehydrogenase, glutamine synthetase), organic acid metabolism (phosphoenolpyruvate carboxylase, NAD- and NADP-dependent malic enzyme, ascorbate peroxidase), and lipid metabolism (acetyl CoA carboxylase, isocitrate lyase) were used to determine how their abundance changed during development. There were marked changes in the abundance of many of these enzymes in both the flesh and seeds. The intercellular location of some enzymes was investigated using immunohistochemistry. Several enzymes (e.g. phosphoenolpyruvate carboxylase and those involved in amino acid metabolism) were associated with tissues likely to function in the transport of imported assimilates, such as the vasculature. Although other enzymes (e.g. NADP-malic enzyme and soluble acid invertase, involved in the metabolism of sugars and organic acids) were largely present in the parenchyma cells of the flesh, their distribution was extremely heterogeneous. This study shows that when considering the metabolism of complex structures such as fruit, it is essential to consider how metabolism is compartmentalized between and within different tissues, even when they are apparently structurally homogeneous.

An immunohistochemical study of the compartmentation of metabolism during the development of grape (Vitis vinifera L.) berries

The compartmentation of key processes in sugar, organic acid and amino acid metabolism was studied during the development of the flesh and seeds of grape (Vitis vinifera L.) berries. Antibodies specific for enzymes involved in sugar (cell wall and vacuolar invertases, pyrophosphate: fructose 6-phosphate phosphotransferase, aldolase, NADP-glyceraldehyde-P dehydrogenase, cytosolic fructose 1,6-bisphosphatase), photosynthesis (Rubisco, fructose 1,6-bisphosphatase, sedoheptulose 1,7-bisphosphatase), amino acid metabolism (cytosolic and mitochondrial aspartate aminotransferases, alanine aminotransferase, glutamate dehydrogenase, glutamine synthetase), organic acid metabolism (phosphoenolpyruvate carboxylase, NAD- and NADP-dependent malic enzyme, ascorbate peroxidase), and lipid metabolism (acetyl CoA carboxylase, isocitrate lyase) were used to determine how their abundance changed during development. There were marked changes in the abundance of many of these enzymes in both the flesh and seeds. The intercellular location of some enzymes was investigated using immunohistochemistry. Several enzymes (e.g. phosphoenolpyruvate carboxylase and those involved in amino acid metabolism) were associated with tissues likely to function in the transport of imported assimilates, such as the vasculature. Although other enzymes (e.g. NADP-malic enzyme and soluble acid invertase, involved in the metabolism of sugars and organic acids) were largely present in the parenchyma cells of the flesh, their distribution was extremely heterogeneous. This study shows that when considering the metabolism of complex structures such as fruit, it is essential to consider how metabolism is compartmentalized between and within different tissues, even when they are apparently structurally homogeneous.

Phosphoenolpyruvate carboxykinase plays a role in interactions of carbon and nitrogen metabolism during grape seed development

Phosphoenolpyruvate carboxykinase (PEPCK) was shown to be present in a range of developing seeds by measurement of its activity and by immunoblotting. Its function was investigated during grape (Vitis vinifera L.) seed development. The maximum abundance of PEPCK coincided with the deposition of storage reserves. At this stage of development, immunohistochemistry showed that PEPCK was very abundant in a layer of cells located at the boundary of developing storage tissues and in the chalaza (close to the termination of the vascular supply to the seed) and was also present in the palisade layer of the seed coat (the inner layer of the outer integument). Earlier in development PEPCK was also present in the developing palisade layer and in the inner region of the nucellus which surrounds the developing endosperm. At later stages of development, PEPCK was located in the outer region of the endosperm. However, PEPCK was present in the phloem of the seed at all stages of development. Feeding of asparagine to developing grape seeds led to a strong induction of PEPCK. We suggest that, in developing grape seeds, both the chalaza and palisade tissue may distribute imported assimilates from the vasculature to the developing storage tissues and that PEPCK may play a role in the metabolism of nitrogenous assimilates during their delivery from the vasculature to the storage tissues.

Early polysomnographic findings and long-term subjective results in sleep apnea patients treated with laser-assisted uvulopalatoplasty

OBJECTIVES/HYPOTHESIS

To examine the long-term results of laser-assisted uvulopalatoplasty (LAUP) for the treatment of patients with obstructive sleep apnea syndrome (OSAS).

STUDY DESIGN

One hundred eighty-two OSAS patients treated with LAUP were followed for an average of 4 years. Of these patients, 131 have completed treatment. Complete polysomnographic data are available on 48 patients. Five patients were eliminated owing to nasal surgery performed during the period between the preoperative and postoperative sleep studies, thus 43 patients were included who had only LAUP treatment. Another three patients were eliminated because their postoperative polysomnograms were performed less than 6 weeks after the last procedure. Complete long-term subjective data are available on 31 patients.

METHODS

Between July 1993 and July 1998, 1038 patients were evaluated for LAUP treatment for snoring and OSAS. Of the 1038 patients, 409 were treated with LAUP and the remaining 629 were treated with other surgical procedures, devices, or behavior modification. The 40 patients who underwent only LAUP treatment for OSAS and have complete polysomnographic data are the focus of this study.

RESULTS

The significant objective polysomnographic findings include a decrease in the respiratory disturbance index (RDI) from 25.0 +/- 2.8 to 15.3 +/- 2.9 (P = < .0001), and a decrease in the apnea index (AI) from 14.6 +/- 2.6 to 9.0 +/- 2.4 (P = .00248). In addition, the percentage of time spent in rapid eye movement (REM) sleep significantly increased after LAUP, from 13.3% +/- 1.0 to 17.6% +/- 1.4 (P = .0149). The long-term subjective results indicate that the presenting complaints were improved after LAUP in 74.9% +/- 4.1 with a mean follow-up of 4.04 years +/- 72 days (median, 4.63 y).

CONCLUSIONS

LAUP remains a safe and effective treatment for carefully selected patients suffering from OSAS. Five years after LAUP was introduced in the United States, objective polysomnographic data demonstrate reduction in the RDI and increased time spent in REM sleep after treatment. In addition, the long-term subjective results show that the presenting symptoms were no longer present in 75% of patients treated with LAUP.

Phosphoenolpyruvate carboxykinase is involved in the decarboxylation of aspartate in the bundle sheath of maize

We recently showed that maize (Zea mays L.) leaves contain appreciable amounts of phosphoenolpyruvate carboxykinase (PEPCK; R.P. Walker, R.M. Acheson, L.I. Tecsi, R.C. Leegood [1997] Aust J Plant Physiol 24: 459-468). In the present study, we investigated the role of PEPCK in C4 photosynthesis in maize. PEPCK activity and protein were enriched in extracts from bundle-sheath (BS) strands compared with whole-leaf extracts. Decarboxylation of [4-14C]aspartate (Asp) by BS strands was dependent on the presence of 2-oxoglutarate and Mn2+, was stimulated by ATP, was inhibited by the PEPCK-specific inhibitor 3-mercaptopicolinic acid, and was independent of illumination. The principal product of Asp metabolism was phosphoenolpyruvate, whereas pyruvate was a minor product. Decarboxylation of [4-14C]malate was stimulated severalfold by Asp and 3-phosphoglycerate, was only slightly reduced in the absence of Mn2+ or in the presence of 3-mercaptopicolinic acid, and was light dependent. Our data show that decarboxylation of Asp and malate in BS cells of maize occurs via two different pathways: Whereas malate is mainly decarboxylated by NADP-malic enzyme, decarboxylation of Asp is dependent on the activity of PEPCK.

Laser-assisted uvulopalatoplasty for the treatment of mild, moderate, and severe obstructive sleep apnea

OBJECTIVES/HYPOTHESIS

Until recently, laser-assisted uvulopalatoplasty (LAUP) has been used to treat only snoring and mild cases of obstructive sleep apnea (OSA). The purpose of this study was to evaluate the efficacy and safety of LAUP in patients with mild, moderate, and severe OSA.

STUDY DESIGN

A prospective study of 38 patients who completed LAUP for the treatment of OSA who were evaluated based on the severity level of their preoperative apnea.

MATERIALS AND METHODS

Between July 1993 and December 1995, 96 patients with a diagnosis of OSA based on polysomnography underwent staged outpatient LAUP treatment. Thirty-eight patients completed treatment and obtained postoperative polysomnography. Postoperative complications and polysomnographic findings were reviewed.

RESULTS

Fifteen patients had a diagnosis of mild apnea, 12 had moderate apnea, and 11 had severe apnea based on preoperative polysomnography. The surgical response rates, defined as greater than or equal to 50% reduction in the postoperative respiratory disturbance index (RDI) and a postoperative RDI of less than 20, were 46.7% in the mild apneics, 41.7% in the moderate apneics, and 45.5% in the severe apneics. Postoperative complications in this series included minor bleeding, oral candidiasis, and temporary velopharyngeal insufficiency. There were no serious complications.

CONCLUSIONS

In the carefully selected and prepared patient with mild, moderate, or severe OSA, LAUP should be considered a surgical option for the treatment of this disorder. LAUP remains a cost-effective and safe alternative to uvulopalatopharyngoplasty.

Guidelines for the use of radio-iodine, thyroid hormone, and treatment of metastatic disease in patients with differentiated thyroid cancer

The treatment of metastatic differentiated thyroid carcinoma is currently at a crossroad. The stunning effect of imaging doses of RAI on subsequent treatment doses is being recognized. Alternatives to RAI imaging for diagnostic purposes are being tested; these include ultrasonography for local and cervical nodal remnants/recurrences, Sestamibi and other isotope scanning that do not require the discontinuation of TSH suppression, and the measurement of circulating thyroglobulin that is rapidly becoming the cornerstone of the detection and the treatment follow-up of metastatic carcinoma.

Levels of urinary beta-core fragment, total oestriol, and the ratio of the two in second-trimester screening for Down syndrome

Levels of beta-core fragment and total oestriol in second-trimester maternal urine samples were measured in 32 Down syndrome pregnancies and 206 control pregnancies. Beta-core fragment and total oestriol values were corrected for the urinary creatinine level and expressed as multiples of the control medians (MOM). In addition, the ratio of the beta-core fragment level to the total oestriol level, without creatinine correction, was calculated, and expressed as MOM values. The median beta-core fragment, total oestriol, and ratio levels in Down syndrome cases were 5.42, 0.64, and 9.32 MOM, respectively. In the Down syndrome pregnancies, 66 per cent of the beta-core fragment levels were above the 95th centile of control levels, while 22 per cent of the total oestriol levels were below the fifth centile of control levels. In combination with maternal age, measurement of beta-core fragment and total oestriol levels in Down syndrome pregnancy resulted in an 80 per cent detection rate at a 5 per cent false-positive rate. Use of the ratio resulted in a univariate detection rate of 72 per cent. In combination with maternal age, the ratio resulted in a detection rate of 81 per cent at a 5 per cent false-positive rate. Based on this unmatched study, the measurement of a ratio of beta-core fragment to total oestriol levels, without the need for creatinine correction, may be useful in screening for fetal Down syndrome in second-trimester urine.

Comparison of 12 assays for detecting hCG and related molecules in urine samples from Down syndrome pregnancies

Urine is a new medium for Down syndrome testing. In an effort to determine the best type of human chorionic gonadotropin (hCG)-related immunoassay for urine testing, we examined 14 Down syndrome and 91 unaffected pregnancy urine samples with 12 established assays. The assays included (a) those that detect hCG beta-core fragment only; (b) those that detect beta-core fragment with less than 18 per cent free beta-subunit cross-reactivity; (c) that which equally detects free beta-subunit and beta-core fragment; and (d) those that detect hCG, free beta-subunit, or combinations thereof. The seven type a and b assays had the highest sensitivity for Down syndrome. The median MOM for Down syndrome was 5.93 (range 4.73-7.53). At a 10 per cent false-positive rate, the median observed detection rate was 93 per cent (range 79-100 per cent) and the median predicted detection rate was 85 per cent (range 69-96 per cent). The assays that did not mainly detect beta-core fragment (types c and d) had poorer screening performance. The median MOM for Down syndrome was 2.70 (range 2.16-3.63 MOM). At a 10 per cent false-positive rate, the median observed detection rate was 50 per cent (range 36-64 per cent) and the median predicted detection rate was 37 per cent (range 21-62 per cent). We infer that the assays that only detect beta-core fragment, or beta-core fragment with minor free beta-subunit cross-reactivity (types a and b), are the better urine-based tests for Down syndrome screening.

UGP--a tumor marker of gynecologic and breast malignancies? Specificity and sensitivity in pretherapeutic patients and the influence of hormonal substitution on the expression of UGP

Urinary gonadotropin peptide (UGP) is a 10,300 Dalton peptide which is present in the urine of pregnant women, those with trophoblast disease and those with, certain nontrophoblastic malignancies. We examined the efficiency of UGP measurement at differentiating benign from malignant gynecologic and breast diseases. UGP was measured in 1355 spot urine samples from 841 patients (343 samples from 323 healthy women and women with benign gynecologic and breast diseases, 1012 samples from 518 women with gynecologic malignant diseases or breast cancer). Using a cutoff of > 3 fmol UGP/mg urinary creatinine the specificity was 97%. The sensitivity of UGP was calculated from pretherapeutically collected samples (n = 210). The sensitivity of the test for all malignancies was 26% (ovarian malignancy (n = 27) 52%, endometrial cancer (n = 25) 32%, cervical cancer (n = 49) 29%, breast cancer (n = 72) 19%, vulvar cancer and vaginal cancer (n = 12) 17% and for carcinoma in situ of the breast or the cervix (n = 20) 0%). We also found significantly higher UGP values in postmenopausal women than in premenopausal women. Hormonal substitution significantly lowered the UGP values.

Uvulopalatopharyngoplasty versus laser-assisted uvulopalatoplasty for the treatment of obstructive sleep apnea

Uvulopalatopharyngoplasty (UPPP) was the first surgical procedure specifically designed to address the palatal abnormalities seen in many patients with obstructive sleep apnea syndrome (OSAS). For adult apneic patients, UPPP remains the most commonly performed operation. Beginning in 1993, laser-assisted uvulopalatoplasty (LAUP) was introduced for the treatment of snoring and sleep apnea. LAUP differs from UPPP because it is performed in the office using only local anesthesia, thus being very cost-effective. Seventy-nine patients with OSAS underwent surgical treatment: 38 treated with LAUP and 41 with UPPP. The overall surgical response rate, defined as a >50% reduction in the postoperative respiratory disturbance index (RDI), was achieved in 21 (51.2%) of UPPP-treated and 18 (47.4%) of LAUP-treated patients. The RDI decreased from 30.3 +/- 3.7 to 22.2 +/- 4.4 events/h in the LAUP patients and from 52.1 +/- 5.0 to 25.5 +/- 2.7 events/h in the UPPP patients. The lowest oxyhemoglobin saturation (LS(aO2)) increased from 72.8 +/- 2.1 to 80.9 +/- 1.3% in the UPPP patients; there was no change in the LAUP patients. Postoperative complications in this series included minor bleeding, oral candidiasis, and temporary velopalatal insufficiency in both groups. In the carefully selected OSAS patient, LAUP should be considered a surgical alternative to UPPP. LAUP may actually be preferable to UPPP in certain cases because LAUP is cost-effective, does not require a general anesthetic or hospitalization, has very few associated complications, and time lost at work is minimal.

Objective assessment of snoring before and after laser-assisted uvulopalatoplasty

Laser-assisted uvulopalatoplasty (LAUP) is an outpatient staged surgical procedure for the treatment of snoring. Each patient undergoes a series of procedures with the end point being patient and bed partner satisfaction in most cases. The purpose of this study was to objectively evaluate the frequency, pattern, and volume of snoring in patients prior to and following each LAUP procedure. A sonographic device, SNAP, which records oronasal respiration, was used to assess patients at home. A digital analysis of the frequency, pattern, and volume was then performed. Twenty-seven patients have been completely evaluated with this recording device. The findings demonstrate that the LAUP procedure alters the snoring sound. The maximum, average, and velum-like respiratory noise loudness all showed a statistically significant decrease when comparing the preoperative snoring to the final recording after treatment was completed. In addition, the fundamental frequency of the snoring increased significantly after each LAUP procedure. No change was seen in the snoring index following treatment. These objective results correlated well with the subjective responses of the patients and their bed partners. These findings are consistent with the hypothesis that the LAUP procedure alters snoring in a favorable manner by both objective data and subjective accounts.

Phosphorylation of phosphoenolpyruvate carboxykinase in plants. Studies in plants with C4 photosynthesis and Crassulacean acid metabolism and in germinating seeds

We have previously shown that phosphoenolpyruvate carboxykinase (PEPCK) is phosphorylated in vivo in the cotyledons of darkened cucumber seedlings and that phosphorylation is reversed by light [Walker and Leegood (1995) FEBS Lett. 362, 70-74]. In this study the molecular mass of PEPCK was estimated in a range of gluconeogenic seedlings and in leaves of C4 plants and plants with Crassulacean acid metabolism (CAM). Phosphorylation of PEPCK was studied in these plants by feeding tissues with [32P]Pi and assessing phosphorylation by SDS/PAGE and autoradiography of either total proteins or of immunoprecipitated protein. In gluconeogenic seedlings and most CAM plants PEPCK had a molecular mass of 74 kDa, whereas in C4 grasses the molecular mass of PEPCK was always smaller and varied from 67-71 kDa. In all gluconeogenic seedlings and leaves of CAM plants PEPCK was phosphorylated, but it was not phosphorylated in all species of C4 grasses studied. In CAM plants, phosphorylation of PEPCK occurred at night and dephosphorylation occurred during the day. In C4 grasses phosphorylation occurred when leaves were darkened and the enzyme was dephosphorylated following illumination, but it was only phosphorylated in those plants with larger (71 kDa) molecular mass forms of PEPCK.