Effects of stroke resistance on rowing economy in club rowers post-season.

In the sport of rowing, increasing the impulse applied to the oar handle during the stroke can result in greater boat velocities; this may be facilitated by increasing the surface area of the oar blade and/or increasing the length of the oars. The purpose of this study was to compare the effects of different rowing resistances on the physiological response to rowing. 5 male and 7 female club rowers completed progressive, incremental exercise tests on an air-braked rowing ergometer, using either low (LO; 100) or high (HI; 150) resistance (values are according to the adjustable "drag factor" setting on the ergometer). Expired air, blood lactate concentration, heart rate, rowing cadence, and ergometer power output were monitored during the tests. LO rowing elicited significantly greater cadences (P<0.01) and heart rates (P<0.05), whereas rowing economy (J · L O(2) equivalents(-1)) was significantly greater during HI rowing (P<0.05). These results suggest that economically, rowing with a greater resistance may be advantageous for performance. Moreover, biomechanical analysis of ergometer rowing support the notion that the impulse generated during the stroke increases positively as a function of rowing resistance. We conclude that an aerobic advantage associated with greater resistance parallels the empirical trend toward larger oar blades in competitive rowing. This may be explained by a greater stroke impulse at the higher resistance.

Use of Leaf Wetness and Temperature to Time Fungicide Applications to Control Botrytis Fruit Rot of Strawberry in Florida.

Botrytis fruit rot (BFR), caused by Botrytis cinerea, is a major disease of strawberry in Florida and is generally controlled by weekly fungicide applications. In this study, disease control programs using fungicides applied on a weekly basis were compared with applications based on three previously published models that correlated disease incidence with weather variables. Field trials were conducted for three seasons on two cultivars, 'Sweet Charlie' and 'Strawberry Festival'. Different thresholds for predicted BFR incidence were evaluated for triggering fungicide applications for the three models. BFR incidence in nontreated control plots of Sweet Charlie and Strawberry Festival was 12.4 and 3.5%, respectively, in 2006-07, 4.2 and 0.8% in 2007-08, and 1.3 and 0.5% in 2008-09. The model of Bulger and associates, with a threshold for disease flower incidence (INFBu) of 0.50, triggered half or fewer fungicide applications compared with a calendar-standard grower program, without significantly increasing BFR incidence or reducing yield. The model of Broome and associates, at a predicted fruit disease incidence threshold (INFBr) of 0.62, performed well but required more fungicide applications than the Bulger model (INFBu ≥ 0.50). The model of Xu and associates, based on field data to predict the incidence of diseased flowers, required more fungicide applications without improving disease control. Use of higher thresholds resulted in fewer applications but increased disease incidence in some cases. The Bulger model utilizing leaf wetness and temperature during the wetness period as input variables and a threshold of INFBu of 0.50 can be used effectively in a disease-forecasting system to time fungicide treatments, and greatly reduced the number of applications without loss of disease control or yield.

Use of Leaf Wetness and Temperature to Time Fungicide Applications to Control Anthracnose Fruit Rot of Strawberry in Florida.

Anthracnose fruit rot (AFR), caused by Colletotrichum acutatum, is a major disease of strawberry in Florida and is generally controlled by weekly fungicide applications. More than 20 applications may be made during the growing season, most commonly using captan and the quinone-outside inhibitors. Field experiments were conducted for three seasons on a susceptible and a partially resistant cultivar to evaluate the effectiveness of timing fungicide applications for managing AFR based on a previously published model by Wilson and associates that uses leaf wetness duration and temperature to predict fruit infection by C. acutatum under controlled conditions. For most treatments, rules were established where captan was applied when the predicted proportion of fruit infected (INF) from the model exceeded 0.15 and pyraclostrobin was applied when INF exceeded 0.5. For one model-timed treatment where captan and pyraclostrobin were applied before symptoms first appeared in the field, disease control was as good as the treatment where calendar weekly applications were made and the model-timed treatment utilized 47% fewer sprays. In treatments where fungicide application began after symptom appearance, the number of applications was reduced further but disease control was 40% less effective. Model-timed fungicide treatments that included pyraclostrobin gave better control than the treatments using captan alone. The model relating leaf wetness and temperature to predict AFR infection can be used effectively in a disease-forecasting system to time fungicide treatments and greatly reduce the number of applications without loss of disease control or yield.

Host range and genetic relatedness of Colletotrichum acutatum isolates from fruit crops and leatherleaf fern in Florida.

Isolates of Colletotrichum acutatum were collected from anthracnose-affected strawberry, leatherleaf fern, and Key lime; ripe-rot-affected blueberry; and postbloom fruit drop (PFD)-affected sweet orange in Florida. Additional isolates from ripe-rot-affected blueberry were collected from Georgia and North Carolina and from anthracnose-affected leatherleaf fern in Costa Rica. Pathogenicity tests on blueberry and strawberry fruit; foliage of Key lime, leatherleaf fern, and strawberry; and citrus flowers showed that isolates were highly pathogenic to their host of origin. Isolates were not pathogenic on foliage of heterologous hosts; however, several nonhomologous isolates were mildly or moderately pathogenic to citrus flowers and blueberry isolates were pathogenic to strawberry fruit. Based on sequence data from the internal transcribed spacer (ITS)1-5.8S rRNA-ITS2 region of the rDNA repeat, the glutaraldehyde-3-phosphate dehydrogenase intron 2 (G3PD), and the glutamine synthase intron 2 (GS), isolates from the same host were identical or very similar to each other and distinct from those isolated from other hosts. Isolates from leatherleaf fern in Florida were the only exception. Among these isolates, there were two distinct G3PD and GS sequences that occurred in three of four possible combinations. Only one of these combinations occurred in Costa Rica. Although maximum parsimony trees constructed from genomic regions individually displayed little or no homoplasy, there was a lack of concordance among genealogies that was consistent with a history of recombination. This lack of concordance was particularly evident within a clade containing PFD, Key lime, and leatherleaf fern isolates. Overall, the data indicated that it is unlikely that a pathogenic strain from one of the hosts examined would move to another of these hosts and produce an epidemic.

Pathotypes and genetic relationship of worldwide collections of Elsinoë spp. causing scab diseases of citrus.

Two scab diseases are recognized currently on citrus: citrus scab, caused by Elsinoë fawcettii, and sweet orange scab, caused by E. australis. Because the two species cannot be reliably distinguished by morphological or cultural characteristics, host range and molecular methods must be used to identify isolates. Four pathotypes of E. fawcettii and two of E. australis have been described to date based on host range. The host specificity and genetic relationships among 76 isolates from Argentina, Australia, Brazil, Korea, New Zealand, and the United States were investigated. Based on pathogenicity tests on eight differential hosts, 61 isolates were identified as E. fawcettii and 15 as E. australis. Of 61 isolates of E. fawcettii, 24 isolates were identified as the Florida broad host range (FBHR) pathotype, 7 as the Florida narrow host range (FNHR) pathotype, 10 as the Tryon's pathotype, and 3 as the "Lemon" pathotype. Two new pathotypes, the "Jingeul" and the satsuma, rough lemon, grape-fruit, clementine (SRGC), are described, and four isolates did not fit into any of the known pathotypes of E. fawcettii. Of the 15 isolates of E. australis from Argentina and Brazil, 9 belonged to the sweet orange pathotype and 6 from Korea to the natsudaidai pathotype. E. fawcettii and E. australis were clearly distinguishable among groups by random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) assays and the E. fawcettii group was divided into three subgroups, A-1, A-2, and A-3. The A-1 group was composed of the FBHR, FNHR, and SRGC pathotypes; some Lemon pathotypes; and the uncertain isolates. The A-2 subgroup included all of the Tryon's pathotype isolates and one of the three Lemon pathotype isolates and the A-3 group contained the Jingeul pathotype isolates. E. australis was differentiated into two groups: B-1, the natsudaidai pathotype isolates, and B-2, the sweet orange pathotype isolates. Isolates of E. fawcettii and E. australis were clearly distinguishable by sequence analysis of the internal transcribed spacer (ITS) region and the translation elongation factor 1 alpha (TEF) gene. There were also fixed nucleotide differences in the ITS and TEF genes that distinguished subgroups separated by RAPD-PCR within species. We confirmed two species of Elsinoë, two pathotypes of E. australis, and at least six pathotypes of E. fawcettii and described their distribution in the countries included in this study.

Curative and Protectant Activity of Fungicides for Control of Crown Rot of Strawberry Caused by Colletotrichum gloeosporioides.

The ability of fungicides to control Colletotrichum crown rot of strawberry caused by C. gloeosporioides was examined over three seasons. A single application of each fungicide was made 2 days before inoculation (2 DBI) or 1 day after inoculation (1 DAI) with conidial suspensions of C. gloeosporioides. The proportion of plants collapsed on one date at the end of each season was evaluated. In a combined analysis, there was a significant fungicide treatment-season interaction (P = 0.004). Percent mortality was 64% over 3 years in control plots that were inoculated with C. gloeosporioides but not treated with fungicide. Captan applied 2 DBI consistently reduced plant mortality (mean mortality = 17%). However, it was not as effective when applied 1 DAI (mean mortality = 46%). Azoxystrobin, pyraclostrobin, and thiophanate-methyl all reduced plant mortality relative to the control if applied 2 DBI (mean mortality = 46% for azoxystrobin, 37% for pyraclostrobin, and 41% for thiophanate-methyl) or 1 DAI (mean mortality = 29% for azoxystrobin, 27% for pyraclostrobin, and 32% for thiophanate-methyl). Results indicated that these fungicides were more effective when applied 1 DAI; however, lower plant mortality was not always observed with postinoculation applications. Cyprodinil + fludioxonil reduced mortality relative to the control, but there was no consistent evidence that it was more effective when applied at 2 DBI (mean mortality = 39%) than when applied 1 DAI (mean mortality = 40%). Similarly, mortality in plots treated with thiram 2 DBI (mean mortality = 30%) or 1 DAI (mean mortality = 32%) was not different. Potassium phosphite did not affect mortality, regardless of the timing of application (2 DBI mean mortality = 61%, 1 DAI mean mortality = 67%). The results indicated that an effective strategy for controlling Colletotrichum crown rot caused by C. gloeosporioides should be based on weekly applications of captan throughout the growing season. Azoxystrobin, pyraclostrobin, or thiophanate-methyl applications should be applied when weather conditions are highly favorable for disease development and the activity of contact fungicides such as captan or thiram might be compromised.

Postbloom fruit drop of citrus and key lime anthracnose are caused by distinct phylogenetic lineages of Colletotrichum acutatum.

Colletotrichum acutatum causes two diseases of citrus, postbloom fruit drop (PFD) and Key lime anthracnose (KLA). PFD is a disease restricted to flowers of sweet orange and most other citrus, and symptoms include petal necrosis, abscission of developing fruit, and the formation of persistent calyces. KLA is a disease of foliage, flowers, and fruits of Key lime only, and symptoms include necrotic lesions on leaves, fruits, twigs, flowers, and blight of entire shoots. The internal transcribed spacers 1 and 2 and the gene encoding the 5.8S ribosomal RNA subunit within the nuclear ribosomal cluster (ITS) and intron 2 of the glyceraldehyde-3-phosphate dehydrogenase gene (G3PD) were sequenced for isolates from PFD-affected sweet orange and KLA-affected Key limes collected in the United States (Florida), Brazil (São Paulo), Mexico, Belize, Costa Rica, and the Dominican Republic to determine if there are consistent genetic differences between PFD and KLA isolates over the geographic area where these diseases occur. Based on the sequence data, isolates clustered into two well-supported clades with little or no sequence variation among isolates within clades. One clade (PFD clade) contained PFD isolates from all countries sampled plus a few isolates from flowers of Key lime in Brazil. The other clade (KLA clade) contained KLA isolates from Key lime foliage from all countries sampled and one isolate from flowers of sweet orange in Mexico. In greenhouse inoculations with PFD and KLA isolates from Florida, isolates from both clades produced PFD symptoms on Orlando tangelo flowers, but KLA-clade isolates produced significantly less severe symptoms. PFD-clade isolates were not pathogenic to Key lime foliage, confirming previous studies. The differentiation of PFD and KLA isolates into two well-supported clades and the pathogenicity data indicate that PFD and KLA are caused by distinct phylogenetic lineages of C. acutatum that are also biologically distinct. PFD is a recently described disease (first reported in 1979) relative to KLA (first reported in 1912) and it had been proposed that strains causing PFD evolved from strains causing KLA eventually losing pathogenicity to Key lime foliage. We reject the hypothesis that PFD strains have diverged from KLA strains recently based on estimated divergence times of haplotypes and it appears that PFD and KLA strains have been dispersed throughout the Americas independently in association with each host.

Colletotrichum fragariae Is a Pathogen on Hosts Other Than Strawberry.

Evidence that Colletotrichum fragariae causes disease on hosts other than strawberry is limited. In the fall of 2006, fungal isolates from silver date palm with leaf spot symptoms and from cyclamen with leaf spot and stem rot symptoms were identified as C. fragariae. After confirming the pathogenicity of the isolates on their host of origin, a representative isolate from each host was compared to C. fragariae and to C. gloeosporioides/Glomerella cingulata isolates from strawberry. Date palm and cyclamen isolates bore conidia on setae, and conidia were tapered and in the size range of C. fragariae reference isolates. Sequence data from the combined internal transcribed spacer (ITS) regions 1 and 2 and the gene for the 5.8 ribosomal RNA from the cyclamen and date palm isolates matched the sequence for C. fragariae reference isolates. Based on these characteristics, it was concluded that the C. fragariae species designation was correct for both isolates. However, the date palm isolate was a weak pathogen on strawberry compared with other isolates and had a distinct AT-rich DNA banding pattern. The ability of the cyclamen isolate to cause crown rot on strawberry was comparable with the strawberry reference isolates, and the AT-rich DNA banding pattern of the cyclamen isolate was identical to the C. fragariae isolates from strawberry. The results indicate that C. fragariae is a pathogen on hosts other than strawberry and that there is more diversity among C. fragariae isolates than previously reported.

The effect of oxidative stress on macrophages and lung epithelial cells: the role of phosphodiesterases 1 and 4.

Reactive oxygen species (ROS) have been implicated in various pulmonary diseases by causing direct injury to lung epithelial cells. Signalling activity of cells through transcription factors such as nuclear factor kappa B (NF-kappaB) and AP-1 have been shown to be regulated by ROS, and the release of pro-inflammatory cytokines demonstrated in the study of inflammatory disease. In this study, we examined the effect of the oxidant tert-butylhydroperoxide (tBHP) on mouse J774 macrophages and its ability to cause the release of the pro-inflammatory cytokine tumour necrosis factor alpha (TNF-alpha). The role of calcium as a signalling molecule was studied using various calcium antagonists. The role of the signalling molecule cAMP was also investigated using phosphodiesterase inhibitors PDE1 and PDE4 families. Oxidative stress was investigated in lung epithelial (A549) cells with and without calcium antagonists and PDE inhibitors with regard to their ability to modulate release of the neutrophil chemoattractant interleukin 8 (IL-8). The oxidant tBHP significantly increased the cytosolic calcium concentration in J774 macrophages, which was prevented by the PDE1 inhibitor. The production of TNF-alpha protein by J774 macrophages was mediated by a pathway involving calcium as addition of calcium antagonists inhibited the tBHP stimulated increase in the cytokine. Inhibitors of both PDE1 and PDE4 completely prevented the tBHP stimulated TNF-alpha release suggesting that the cAMP pathway may be important in the oxidant induced signalling pathway leading to gene expression of pro-inflammatory cytokines. In the presence of oxidant alone, A549 epithelial cells released significant amounts of IL-8, which was inhibited by both calcium antagonist treatment and PDE inhibition treatment. These data suggest that ROS-mediated lung inflammation could be mediated at least in part by calcium and elevated PDE activity associated with decreased cAMP in both macrophages and epithelial cells. Inhibition of these pathways may provide a route for treatment of inflammatory lung diseases.

Selection for Pathogenicity to Strawberry in Populations of Colletotrichum gloeosporioides from Native Plants.

ABSTRACT Colletotrichum gloeosporioides causes a serious crown rot of strawberry and some isolates from native plants are pathogenic to strawberry. C. gloeosporioides from lesions on wild grape and oak were sampled at two sites adjacent to commercial strawberry fields in Florida and two distant sites. Random amplified polymorphic DNA (RAPD) marker data and restriction enzyme digests of amplified rDNA were used to determine whether isolates were from the same C. gloeosporioides subgroup that infects strawberry. There were 17 to 24 native host isolates from each site that clustered with a group of strawberry crown isolates based on RAPD markers. Among strawberry isolates, there were two rDNA genotypes identified by restriction enzyme analysis. Both genotypes were present among native host isolates sampled from all four sites. There was some evidence that the different rDNA genotypes differentiated two closely related subpopulations, although the proportion of pathogenic isolates from native hosts among the two different genotypes was not different. The incidence of isolates pathogenic to strawberry was greater at sites close to strawberry fields relative to sites distant from strawberry fields for isolates with a BstUI(-)/MspI(+) rDNA genotype (44 versus 13%), a BstUI(+)/MspI(-) genotype (57 versus 16%), or when both genotypes were analyzed together (46 versus 15%). Based on these results, it appears that the C. gloeosporioides subgroup that causes crown rot on strawberry is widely distributed in Florida and that selection for pathogenicity on strawberry occurs in the area where this host is grown in abundance.

Effect of Fungicides and Storage Conditions on Postharvest Development of Citrus Black Spot and Survival of Guignardia citricarpa in Fruit Tissues.

Citrus black spot (CBS) is caused by Guignardia citricarpa, which incites lesions on citrus fruit and can induce fruit drop. Quiescent infections occur during the spring and summer, and symptoms appear at fruit maturity or after harvest. Thus, fruit from citrus areas affected by CBS represent a risk for introduction of this pathogen into new areas. The effects of preventive field fungicide programs, postharvest fungicide drenches, packinghouse fungicide applications, and storage temperatures on postharvest symptom development and viability of G. citricarpa in lesions were evaluated in five experiments on Murcott tangor, Valencia oranges, and lemons. Preventive field treatments and fruit storage at 8°C consistently reduced postharvest CBS development, whereas a postharvest fungicide drench or packinghouse treatment with fungicides had no effect on postharvest symptom development. In a separate experiment, postharvest appearance of symptoms was related to the percentage of fruit with symptoms at harvest. The preventive field fungicide program also consistently reduced the percentage of isolation of G. citricarpa from affected fruit, whereas storage temperature and packinghouse fungicide treatment gave variable results. The viability of the fungus declined with storage time of fruit after harvest, but G. citricarpa could still be readily isolated regardless of treatment. In another experiment, the viability of the fungus in detached fruit or peel was minimally affected by temperature or moisture during storage. The frequency of successful isolation declined with time, but G. citricarpa was still recovered frequently from symptomatic tissue at later times. The most effective means to reduce postharvest development of symptoms is through preventive application of fungicides during the fruit growing season and storage of harvested fruit at cold temperatures. None of the measures evaluated substantially reduced viability of G. citricarpa, and the pathogen would likely be introduced on symptomatic fruit from citrus areas with CBS.

First Report of Colletotrichum acutatum Causing a Leaf Spot on Myrica cerifera in Florida.

Wax myrtle (Morella cerifera (synonym Myrica cerifera) (L.) Small) is a native tree used in Florida landscapes. In the summer of 2005 and spring of 2006, small necrotic spots were observed on young leaves in two commercial nurseries in central Florida. Lesions were dark brown-to-black and eventually coalesced to form large, irregular necrotic areas. Leaves with large lesions abscised prematurely, defoliating the entire plant. Conidia formed on acervuli were observed on the surface of the largest lesions and were tentatively identified as a Colletotrichum sp. Isolations from the edges of lesions were made on potato dextrose agar (PDA) after surface disinfestation of leaf pieces in 0.6% NaOCl for 30 sec. Red chromogenic colonies developed after 5 days of incubation at 24°C. Colonies produced hyaline, oblong conidia with pointed ends averaging 14 × 4 µm and were identified as Colletotrichum acutatum J.H. Simmonds (1). The sequence from internal transcribed spacer regions 1 and 2 and the 5.8s rRNA gene of the rDNA repeat for an isolate (GenBank Accession No. DQ839609) was 100% identical to sequence from the same region of 36 C. acutatum isolates in the NCBI database. These isolates came from at least 16 different hosts, including seven ornamental hosts. There were three isolates from blueberry among the matches (Accession Nos. AB219029, AJ301911, and AJ301905), and the rDNA sequence was also identical to the sequence obtained in our laboratory for a chromogenic C. acutatum isolate from blueberry. Three single-spore isolates were tested for pathogenicity on potted plants in the greenhouse. Two young shoots were spray inoculated with a suspension (1 × 106 conidia/ml) of each isolate. Shoots were covered with a plastic bag for 24 h and maintained at 26.5°C. Two shoots were sprayed with sterile water as a control and similarly covered. All isolates produced brown spots on the youngest leaves 3 to 5 days after inoculation; no symptoms developed on control shoots. The fungus was reisolated from all inoculated shoots. To our knowledge, this is the first report of C. acutatum on wax myrtle in Florida. The disease has a potential to spread and become a significant problem for the cultivation of this species in ornamental nurseries in Florida. Reference: (1) J. H. Simmonds. Qld. J. Agric. Anim. Sci. 22:437, 1965.

Resistance of Strawberry Cultivars to Crown Rot Caused by Colletotrichum gloeosporioides Isolates from Florida Is Nonspecific.

Isolates of Colletotrichum gloeosporioides from strawberry (Fragaria × ananassa) and native grape were tested for virulence on strawberry cultivars in field experiments for three seasons. Isolate aggressiveness and cultivar resistance were determined by the proportion of plants killed at a defined time. Each year, four to six isolates were inoculated on four to seven different cultivars, with a subset of isolates and cultivars evaluated again the next season. On the dates that disease was evaluated, incidence ranged from 10 to 84% for individual cultivars. Cultivar and isolate effects were significant in all three seasons, but there was no significant cultivar by isolate interaction in any season. Thus, resistance to C. gloeosporioides appears to be nonspecific. In the third season, one isolate of Colletotrichum fragariae from strawberry and one from oak were included. There was no significant cultivar by isolate interaction detected for this species, although there were significant differences among cultivars and isolates. When the resistance of cultivars to both species was compared, the rankings of cultivars were similar, but a modest cultivar by species interaction was evident. The cultivar Treasure was more resistant to crown rot caused by either species than any other cultivar tested.

Development of a Reduced Use Fungicide Program for Control of Botrytis Fruit Rot on Annual Winter Strawberry.

Crop phenology and epidemiological information were used to design a reduced use fungicide program for control of Botrytis fruit rot in winter annual strawberry. Fungicide spray programs during early and late periods of the season using high and low rates of captan were evaluated with or without second peak bloom applications of fenhexamid during the 1999-2000 and 2000-2001 seasons. During the early harvest period, low rates of captan were as effective as high rates for controlling Botrytis fruit rot and maintaining yield. Late in the season, treatments with fenhexamid over the peak bloom period significantly improved control of Botrytis fruit rot and increased marketable yield. Application of both captan and fenhexamid during the second peak bloom did not reduce Botrytis fruit rot incidence or improve yield compared with fenhexamid alone during this time period. Late season applications of captan may be reduced or eliminated when bloom applications of fenhexamid are being applied without affecting Botrytis fruit rot control. The study generated new recommendations for use of low-rate applications of captan during the early season and applications of fenhexamid during the second peak bloom period for winter annual strawberry production in Florida.

Sub-family selective actions in the ability of Erk2 MAP kinase to phosphorylate and regulate the activity of PDE4 cyclic AMP-specific phosphodiesterases.

Expressed in intact cells and in vitro, PDE4B and PDE4C isoenzymes of cyclic nucleotide phosphodiesterase (PDE), in common with PDE4D isoenzymes, are shown to provide substrates for C-terminal catalytic unit phosphorylation by the extracellular signal-regulated kinase Erk2 (p42(MAPK)). In contrast, PDE4A isoenzymes do not provide substrates for C-terminal catalytic unit phosphorylation by Erk2. Mutant PDE4 enzymes were generated to show that Erk2 phosphorylation occurs at a single, cognate serine residue located within the C-terminal portion of the PDE4 catalytic unit. PDE4 long-form isoenzymes were markedly inhibited by Erk2 phosphorylation. The short-form PDE4B2 isoenzyme was activated by Erk2 phosphorylation. These functional changes in PDE activity were mimicked by mutation of the target serine for Erk2 phosphorylation to the negatively charged amino acid, aspartic acid. Epidermal growth factor (EGF) challenge caused diametrically opposed changes in cyclic AMP levels in COS1 cells transfected to express the long PDE4B1 isoenzyme compared to cells expressing the short PDE4B2 isoenzyme. We suggest that PDE4 enzymes may provide a pivotal point for integrating cyclic AMP and Erk signal transduction in cells with 4 genes encoding enzymes that are either insensitive to Erk2 action or may either be activated or inhibited. This indicates that PDE4 isoenzymes have distinct functional roles, giving credence to the notion that distinct therapeutic benefits may accrue using either PDE4 subfamily or isoenzyme-selective inhibitors.

Hyperlactatemia and pulmonary lactate production in patients with fulminant hepatic failure.

STUDY OBJECTIVES: To determine whether the lungs of patients with fulminant hepatic failure release lactate, and if so, whether this release relates to systemic lactate concentration or acid base status. Another objective was to examine the accuracy of lactate flux calculations in critically ill patients. DESIGN: Prospective observational study. SETTING: The ICU of a major teaching hospital. PATIENTS: Twelve patients with fulminant hepatic failure; 30 other critically ill patients in whom a pulmonary artery catheter was in place. INTERVENTIONS: None. MEASUREMENT AND RESULTS: The precision of whole-blood lactate measurements was assessed in 30 patients with critical illnesses of variable etiology who had a wide range of arterial lactate concentrations. The reliability of lactate measurements decreased with increasing lactate concentration. In each patient with liver failure, pulmonary lactate flux was calculated on three occasions using the Fick principle. Arterial blood lactate concentration was consistently higher than venous concentrations, indicating lactate release by the lungs (mean difference, 0.15 mmol/L; 95% confidence interval, 0.09 to 0.21; p<0.001). Mean pulmonary lactate production for the 12 patients was 83 mmol/h (range, 22 to 210 mmol/h). No patient had significant acute lung injury. Correlations were found among the arterial lactate concentration and both the arteriovenous (AV) lactate difference (p<0.025) and pulmonary lactate production (p<0.05), but not with acid-base status or cardiac output. The reliability of individual AV lactate difference calculations and pulmonary lactate flux calculations was poor. CONCLUSION: The lungs release lactate in patients with fulminant hepatic failure at a rate proportional to the degree of systemic hyperlactatemia. However, the measurement errors associated with pulmonary lactate flux calculations using the Fick principle are large, so individual measurements should be interpreted with caution.

The haemodynamic effects of intermittent haemofiltration in critically ill patients.

The haemodynamic effects of intermittent high volume venovenous haemofiltration were studied in 13 critically ill patients. The mean negative fluid balance during filtration was 1.21 and the mean duration of treatment 3 h 40 min. The cardiac index fell initially (4.5 +/- 0.2 to 3.8 +/- 0.21/min/m2; p less than 0.05) but then remained stable throughout treatment before returning to baseline at the end of haemofiltration. The mean arterial pressure was unchanged with an increase in the systemic vascular resistance (651 +/- 33 to 765 +/- 65 dyne.s/cm5; p less than 0.05) suggesting that vascular responsiveness is maintained during haemofiltration.

Adrenaline in treatment of septic shock: effects on haemodynamics and oxygen transport.

The effects of adrenaline on haemodynamics and oxygen transport were studied in 13 patients with septic shock persisting after optimal fluid loading. Adrenaline was administered by intravenous infusion at an increasing dose until no further benefit was seen. There were significant increases in mean arterial pressure, cardiac index, left ventricular stroke work index and oxygen delivery index. There was no significant change in oxygen consumption although the trend was towards an increase. There was a significant reduction in oxygen extraction ratio, but no change in shunt fraction. Adrenaline would appear to have beneficial haemodynamic effects in septic shock.

Genetic and Pathogenic Analyses of Colletotrichum gloeosporioides Isolates from Strawberry and Noncultivated Hosts.

ABSTRACT Colletotrichum crown rot of strawberry in Florida is caused primarily by Colletotrichum gloeosporioides. To determine potential inoculum sources, isolates of Colletotrichum spp. from strawberry and various noncultivated plants growing in the areas adjacent to strawberry fields were collected from different sites. Species-specific internal transcribed spacer primers for C. gloeosporioides and C. acutatum were used to identify isolates to species. Random amplified polymorphic DNA (RAPD) markers were used to determine genetic relationships among isolates recovered from noncultivated hosts and diseased strawberry plants. Selected isolates also were tested for pathogenicity on strawberry plants in the greenhouse. In all, 39 C. gloeosporioides and 3 C. acutatum isolates were recovered from diseased strawberry crowns, and 52 C. gloeosporioides and 1 C. acutatum isolate were recovered from noncultivated hosts. In crown inoculation tests, 18 of the 52 C. gloeosporioides isolates recovered from noncultivated hosts were pathogenic to strawberry. Phylogenetic analysis using RAPD marker data divided isolates of C. gloeosporioides from noncultivated hosts into two separate clusters. One cluster contained 50 of the 52 isolates and a second cluster contained 2 isolates that were homothallic in culture. Isolates from strawberry were interspersed within the cluster containing the 50 isolates that were recovered from noncultivated hosts. The results are not inconsistent with the hypothesis that C. gloeosporioides isolates obtained from strawberry and noncultivated hosts adjacent to strawberry fields are from the same population and that noncultivated hosts can serve as potential inoculum sources for Colletotrichum crown rot of strawberry.

Etiology and Population Genetics of Colletotrichum spp. Causing Crown and Fruit Rot of Strawberry.

ABSTRACT Isolates of Colletotrichum spp. from diseased strawberry fruit and crowns were evaluated to determine their genetic diversity and the etiology of the diseases. Isolates were identified to species using polymerase chain reaction primers for a ribosomal internal transcribed spacer region and their pathogenicity was evaluated in bioassays. Isolates were scored for variation at 40 putative genetic loci with random amplified polymorphic DNA and microsatellite markers. Only C. acutatum was recovered from diseased fruit. Nearly all isolates from crowns were C. gloeosporioides. In crown bioassays, only isolates of C. gloeosporioides from strawberry caused collapse and death of plants. A dendrogram generated from the genetic analysis identified several primary lineages. One lineage included isolates of C. acutatum from fruit and was characterized by low diversity. Another lineage included isolates of C. gloeosporioides from crowns and was highly polymorphic. The isolates from strawberry formed distinctive clusters separate from citrus isolates. Evaluation of linkage disequilibrium among polymorphic loci in isolates of C. gloeosporioides from crowns revealed a low level of disequilibrium as would be expected in sexually recombining populations. These results suggest that epidemics of crown rot are caused by Glomerella cingulata (anamorph C. gloeosporioides) and that epidemics of fruit rot are caused by C. acutatum.