A comparative analysis of agronomic water-use efficiency and its proxy measures as derived from key morpho-physiological and supportive quantitative genetics attributes of perennial ryegrass under imposed drought.

Water-use efficiency (WUE) is an under-researched but very important drought tolerance trait in forage breeding. This research estimated quantitative genetic parameters of morpho-physiological traits linked to agronomic water-use efficiency (WUEA) and its proxy measures based on δ13C (WUEi) or gas exchange (evapotranspiration, WUEAET, or stomatal conductance WUEASC) of genotypes from half-sib families of Lolium perenne L. (PRG) in a simulated summer drought cycle. Principal component analysis (PCA) of trait data distinguished a group of PRG genotypes where high WUEA and dry matter yield was associated with deep rooting, leaf hydration at more negative leaf osmotic and water potential, and reduced soil moisture depletion. Plants with this trait association sustained net assimilation and postdefoliation regrowth in drought. However, WUEi, WUEASC, and WUEAET were poorly correlated with most traits of interest at p < .05. Another PCA revealed a weak association between WUEA and its proxy measures under conditions tested. Quantitative genetic parameters including high estimates of narrow-sense heritability (hn2>0.7;p<.05) of WUEA and related traits emphasized the genetic potential of the key trait combination for selecting PRG for improved drought tolerance. Research findings highlight the relative importance of WUEA and its proxy measures in the broad definition of PRG drought tolerance for breeding purposes.

Host-dependent patterns of tissue injury in invasive pulmonary aspergillosis.

Invasive pulmonary aspergillosis (IPA) is an important cause of morbidity and mortality in neutropenic, nonneutropenic, and other immunocompromised patients. We therefore compared the patterns of infection and inflammation among 3 cohorts of immunocompromised patients with profound neutropenia, nonneutropenic immunosuppression, and hematopoietic stem cell transplantation. Lesions of IPA in neutropenic patients and hematopoietic stem cell transplant (HSCT) recipients were similar and consisted predominantly of angioinvasion and intraalveolar hemorrhage. The frequency of these histologic findings in neutropenic patients and HSCT recipients differed significantly from those of nonneutropenic patients (P < .05). It is noteworthy that even if HSCT recipients have normal peripheral blood neutrophil counts, there may be no influx into sites of infection. In the nonneutropenic cohort, lesions of IPA consisted mainly of neutrophilic and monocytic infiltrates and inflammatory necrosis. Thus, the status of innate host defenses contributes significantly to the histologic patterns observed in IPA.

A functional-structural model of elongation of the grass leaf and its relationships with the phyllochron.

The emergence of a regular phyllochron from the dynamic processes of leaf initiation, leaf elongation and whorl construction suggests causal relationships between leaf elongation and leaf emergence. This paper presents a hypothesis as to how the ontogeny of the growth zone of leaves is triggered by emergence events, and implements it in a dynamic model of leaf elongation. Two different experiments, presenting two contrasted cases of relationships between leaf emergence and kinetics of leaf elongation, were analysed and interpreted with the model in terms of the functioning of the growth zone. Analysis of elongation kinetics revealed that the hypothesis allows for several contrasted elongation patterns that were observed, and for a regular phyllochron emerging from the variable dynamic of elongation. The model was able to simulate these patterns, and helped to identify the mechanisms underlying the key points of the analysis. The hypothesis is not demonstrated, but its coherence and robustness are established, which should inform a renewal of the modelling of leaf elongation in architectural models.

Dosage-dependent antifungal efficacy of V-echinocandin (LY303366) against experimental fluconazole-resistant oropharyngeal and esophageal candidiasis.

V-echinocandin (VER-002; LY303366) is a semisynthetic derivative of echinocandin B and a potent inhibitor of fungal (1, 3)-beta-D-glucan synthase. We studied the antifungal efficacy, the concentrations in saliva and tissue, and the safety of VER-002 at escalating dosages against experimental oropharyngeal and esophageal candidiasis caused by fluconazole-resistant Candida albicans in immunocompromised rabbits. Study groups consisted of untreated controls, animals treated with VER-002 at 1, 2.5, and 5 mg/kg of body weight/day intravenously (i.v.), animals treated with fluconazole at 2 mg/kg/day i.v., or animals treated with amphotericin B at 0.3 mg/kg/day. VER-002-treated animals showed a significant dosage-dependent clearance of C. albicans from the tongue, oropharynx, esophagus, stomach, and duodenum in comparison to that for untreated controls. VER-002 also was superior to amphotericin B and fluconazole in clearing the organism from all sites studied. These in vivo findings are consistent with the results of in vitro time-kill assays, which demonstrated that VER-002 has concentration-dependent fungicidal activity. Esophageal tissue VER-002 concentrations were dosage proportional and exceeded the MIC at all dosages. Echinocandin concentrations in saliva were greater than or equal to the MICs at all dosages. There was no elevation of serum hepatic transaminase, alkaline phosphatase, bilirubin, potassium, or creatinine levels in VER-002-treated rabbits. In summary, the echinocandin VER-002 was well tolerated, penetrated the esophagus and salivary glands, and demonstrated dosage-dependent antifungal activity against fluconazole-resistant esophageal candidiasis in immunocompromised rabbits.

Pharmacokinetics of oral zidovudine entrapped in biodegradable nanospheres in rabbits.

The pharmacokinetic profile of oral zidovudine entrapped in a 50:50 polyactide-coglycolide matrix (nanospheres) was compared to those of standard oral and parenteral zidovudine formulations in rabbits. The bioavailability of zidovudine nanospheres at 50 mg/kg of body weight was 76%, and this dose achieved prolonged exposure to zidovudine compared to standard formulations without an increase in the drug's peak concentration.

Antifungal efficacy, safety, and single-dose pharmacokinetics of LY303366, a novel echinocandin B, in experimental pulmonary aspergillosis in persistently neutropenic rabbits.

LY303366 is a novel semisynthetic derivative of echinocandin B and a potent inhibitor of fungal (1,3)-beta-D-glucan synthase. The antifungal efficacy and safety of LY303366 were investigated in treatment and prophylaxis of primary pulmonary aspergillosis due to Aspergillus fumigatus in persistently neutropenic rabbits. Treatment study groups were either not treated (controls) or treated with amphotericin B (AmB) at 1 mg/kg of body weight per day or with LY303366 at 1, 5, 10, and 20 mg/kg/day. In rabbits treated with LY303366, there was a significant improvement in survival and a reduction in organism-mediated pulmonary injury measured by the number of infarcts, total lung weight, and ultrafast computerized tomography scan pulmonary lesion score. Rabbits receiving prophylactic LY303366 also demonstrated significant improvement in survival and reduction in organism-mediated pulmonary injury. AmB and LY303366 had comparable therapeutic efficacies by all parameters with the exception of reduction in tissue burden of A. fumigatus, where AmB was superior to LY303366. LY303366 demonstrated a dose-dependent effect on hyphal injury with progressive truncation, swelling, and vacuolization. LY303366 administered in single doses of 1, 5, 10, and 20 mg/kg demonstrated dose-proportional increases in the maximum concentration of drug in plasma and the area under the concentration-time curve from 0 to 72 h with no changes in plasma drug clearance. The 1-mg/kg dosage maintained plasma drug levels above the MIC for 18 h, and dosages of >/=5 mg/kg maintained plasma drug levels above the MIC for the entire 24-h dosing interval. There was no significant elevation of the concentrations of hepatic transaminases or creatinine in serum in LY303366-treated rabbits. In summary, LY303366 improved survival and decreased pulmonary injury with no apparent toxicity in the treatment and prevention of invasive pulmonary aspergillosis in persistently neutropenic rabbits.

Increased serum concentrations of interleukin-10 in patients with hepatosplenic candidiasis.

Hepatosplenic candidiasis (HSC) becomes clinically overt in cancer patients upon recovery from neutropenia. HSC may be a consequence of a Th1-Th2 imbalance, characterized by increased serum levels of one or more cytokines. Serum levels of two immunosuppressive cytokines, markers of the Th2 pathway, interleukin (IL)-4 and IL-10 were measured by ELISA in 10 patients with HSC (22 samples) and compared with 19 healthy blood donors, 13 patients with cancer but no infection (23 samples), and 11 patients with cancer and various bacterial infections (17 samples). IL-4 was undetectable in all controls and patients. By contrast, levels of IL-10 were increased in HSC patients compared with levels in healthy donors and cancer patients without infection (P < .001) or with bacterial infections (P < .01). These findings indicate that IL-10 but not IL-4 is increased in patients with HSC and suggest that IL-10 plays a role in the pathogenesis of this infection.

Quantitative urine cultures do not reliably detect renal candidiasis in rabbits.

The significance of quantitative urine cultures in patients at risk for hematogenous disseminated candidiasis is controversial. While various concentrations of Candida spp. in urine have been suggested as critical cutoff points in the diagnosis of renal candidiasis, other investigators consider quantitative cultures less critical in diagnosing upper tract infections. To determine the significance of quantitative urine cultures in renal candidiasis, we studied serial quantitative urinary cultures of Candida albicans in a rabbit model of hematogenous infection. Of 197 urine samples from 34 infected animals, 144 were culture positive, with a sensitivity of 73.1% for urine cultures and a lower limit of detection of 10 CFU/ml. The yield of urine cultures varied according to severity and duration of infection. The mean renal and urinary concentrations of C. albicans from rabbits with subacute candidiasis differed significantly from those from rabbits with acute candidiasis (P = 0.013 and P < or = 0.001, respectively). During the first 4 days of subacute renal candidiasis, more than one-half of all urine cultures were negative for C. albicans. Only 12 (8.1%) of 148 urine cultures in animals with subacute renal candidiasis had concentrations of > 10(3) CFU/ml, 2.7% had concentrations of > 10(4) CFU/ml, and none were > or = 10(5) CFU/ml. By comparison, all urine cultures from the animals with lethal acute renal candidiasis had higher concentrations of C. albicans and were positive throughout the course of infection. Urinary concentrations of C. albicans were not predictive of the amount of Candida in the kidney (r < or = 0.49) and did not correlate with survival (r = 0.0232). However, the renal concentration of C. albicans (in CFU/gram) inversely correlated with the duration of survival (in days) of rabbits with renal candidiasis (r = 0.76; P < 0.001). These findings indicate that a negative urine culture in rabbits does not preclude the presence of renal candidiasis. The interpretation of a urine culture positive at any concentration, on the other hand, must involve an analysis of the risk factors for renal candidiasis, for any urinary concentration of C. albicans may reflect kidney infection.

Diagnosis and therapeutic monitoring of invasive candidiasis by rapid enzymatic detection of serum D-arabinitol.

BACKGROUND: Using a rapid automated enzymatic assay, we prospectively investigated serum D-arabinitol (DA), a biochemical marker of invasive candidiasis, in a large population of high-risk patients to determine its potential diagnostic, therapeutic, and prognostic significance in invasive candidiasis. PATIENTS AND METHODS: A total of 3,223 serum samples were collected from 274 patients with cancer. Serum DA concentrations were determined in coded serum samples analyzed by rapid enzymatic assay. Creatinine also was analyzed in the same system to determine a serum DA and creatinine ratio (DA/Cr). The sensitivity, specificity, correlation with therapeutic response, and prognostic significance were analyzed for all patient study groups. RESULTS: A DA/Cr of > or = 4.0 mumol/L per mg/dL was detected in 31 (74%) of all 42 cases of fungemia and 25 (83%) of the 30 cases of the subset of persistent fungemia. Elevated DA/Cr was detected in 4 (40%) of 10 patients with tissue-proven, deeply invasive candidiasis and negative blood cultures (eg, hepatosplenic candidiasis or localized abscess) and 7 (44%) of 16 cases of deep mucosal candidiasis (eg, esophageal candidiasis). Elevated serial DA/Cr levels also were detected in persistently febrile and granulocytopenic patients requiring empirical amphotericin B. Among 26 assessable cases of fungemia, abnormally elevated DA/Cr values were detected in 14 (54%) before, 10 (38%) after, and 2 (8%) simultaneously with the first microbiologic report of fungemia. The trends of serial DA/Cr values correlated with therapeutic response in 29 (85%) of 34 patients with assessable cases of fungemia, decreasing in 8 (89%) of 9 patients with clearance of fungemia and increasing in 21 (84%) of 25 patients with persistence of fungemia. Among the 34 assessable patients with fungemia, mortality was directly related to the trend of serial DA/Cr determinations over time: 71% among fungemic patients who had persistently elevated or increasing DA/Cr, and 18% among the fungemic patients who had resolving DA/Cr or never had elevated DA/Cr (P < 0.01). CONCLUSIONS: Rapid enzymatic detection of DA in serially collected serum samples from high-risk cancer patients permitted detection of invasive candidiasis, early recognition of fungemia, and therapeutic monitoring in DA-positive cases. Serially collected serum DA determinations complement blood cultures for improving detection and monitoring therapeutic response in patients at risk for invasive candidiasis.

Therapeutic monitoring of experimental invasive pulmonary aspergillosis by ultrafast computerized tomography, a novel, noninvasive method for measuring responses to antifungal therapy.

Pulmonary infiltrates in neutropenic hosts with invasive aspergillosis are due to vascular invasion and hemorrhagic infarction. In order to measure the effect of antifungal compounds on this organism-mediated tissue injury, we monitored the course of pulmonary infiltrates by serial ultrafast computerized tomography (UFCT) in persistently granulocytopenic rabbits with experimental invasive pulmonary aspergillosis. The course of pulmonary lesions measured by serial UFCT scans was compared with those measured by conventional chest radiography, histopathological resolution of lesions, and microbiological clearance of Aspergillus fumigatus. Treatment groups included either amphotericin B colloidal dispersion in dosages of 1, 5, and 10 mg/kg of body weight per day intravenously or conventional desoxycholate amphotericin B at 1 mg/kg/day intravenously. Therapeutic monitoring of pulmonary lesions by UFCT demonstrated a significant dose-response relationship. Lesions continued to progress in untreated controls, whereas lesions in treated rabbits initially increased and then decreased in response to antifungal therapy in a dosage-dependent manner (P < or = 0.05 to P < or = 0.005, depending upon the groups compared). This same trend of resolution of lesions in response to antifungal therapy was also demonstrated by postmortem examination and by microbiological clearance of the organism. These data indicated that amphotericin B colloidal dispersion at 5 and 10 mg/kg/day exerted a more rapid rate of clearance of lesions than conventional amphotericin B. UFCT was more sensitive than conventional chest radiography in detecting lesions due to invasive pulmonary aspergillosis (P < 0.05 to P < 0.005, depending upon the groups compared). These findings establish a correlation among UFCT-defined lesions, microbiological response, and resolution of pathologically defined lesions in experimental invasive pulmonary aspergillosis. Serial monitoring of UFCT-defined lesions of aspergillosis provides a novel system for determining the antifungal response of organism-mediated tissue injury.

Serum D-arabinitol measured by automated quantitative enzymatic assay for detection and therapeutic monitoring of experimental disseminated candidiasis: correlation with tissue concentrations of Candida albicans.

In order to further understand serum D-arabinitol (DA) as a marker for the diagnosis of disseminated candidiasis and for monitoring response to antifungal therapy, we studied the serum levels of this Candida carbohydrate metabolite by rapid automated enzymatic assay in rabbits with experimental disseminated candidiasis. The enzymatic reaction steps were performed on a standard automated clinical chemistry analyser. As a correction for renal impairment, data were expressed as serum D-arabinitol/creatinine ratio (DA/Cr). Serum creatinine concentrations were determined from the same sample with the same instrument, thereby allowing rapid determination of the DA/Cr within one laboratory. The DA/Cr was determined in 321 samples from 132 rabbits. The mean serum DA/Cr in 31 normal non-infected rabbits was 1.51 +/- 0.2 microM mg-1 dl-1. Among 84 rabbits with disseminated candidiasis and pre-terminal samples, there was a direct correlation between DA/Cr and tissue concentration of Candida albicans (r = 0.80; P < 0.001). A threshold of elevated DA/Cr (> or = 3.0 microM mg-1 dl-1) was evident in rabbits with a tissue concentration of C. albicans > or = 3 x 10(4) colony forming units (CFU) g-1. Elevated DA/Cr was detected in 48 (89%) of 54 rabbits at a C. albicans tissue concentration of > or = 3 x 10(4) CFU g-1 vs. one (3%) of 30 rabbits with < 3 x 10(4) CFU g-1 (P < 0.0001). Among all 101 rabbits with disseminated candidiasis, an elevated DA/Cr was detected at any point during infection in 60 (92%) of 65 rabbits having a C. albicans tissue concentration > or = 3 x 10(4) CFU g-1 vs. 13 (36%) of 36 rabbits with < 3 x 10(4) CFU g-1 (P < 0.0001). The relationship between the tissue response to antifungal therapy and change in DA/Cr was then further analysed. Ten (91%) of 11 rabbits with a tissue-proven response to antifungal therapy (defined as > or = 10(2)-fold reduction of CFU g-1 in comparison to untreated controls) had a > 50% reduction in elevated DA/Cr levels. By comparison, 10 (83%) of 12 treated rabbits with no response to therapy had persistently elevated DA/Cr levels (P < 0.001). These findings provide an experimental basis for understanding the patterns of expression of serum DA in disseminated candidiasis and further indicate that serial DA/Cr measurements may be useful for diagnosis and therapeutic monitoring of disseminated candidiasis.

Detection of circulating candida enolase by immunoassay in patients with cancer and invasive candidiasis.

BACKGROUND: Invasive candidiasis is a major nosocomial infection that is difficult to diagnose. Few biochemically defined markers of invasive candidiasis are known. Initial findings suggested that the presence of candida enolase in the blood may be a novel marker for invasive candidiasis. METHODS: We tested 170 patients at high risk for invasive candidiasis for candida enolase antigenemia. All the patients had cancer and neutropenia. We detected antigen using a double-sandwich liposomal immunoassay for candida enolase in serially collected serum samples. Invasive candidiasis was proved by finding candida species in deep nonmucosal tissue, blood cultures, or both. Antigen testing was performed with the investigator blinded to tissue or culture diagnosis. RESULTS: Among 24 patients with proved invasive candidiasis, 149 serum samples were tested for enolase antigenemia; 80 were positive and 69 negative (sensitivity per sample, 54 percent). Multiple sampling improved the detection of antigenemia, which was found in 11 of 13 proved cases of deep tissue infection (85 percent) and in 7 of 11 proved cases of fungemia (64 percent). Specificity was 96 percent as measured against control groups including patients with mucosal colonization, bacteremia, and other deep mycoses. Antigenemia was detected in the absence of fungemia in 5 cases of deep tissue candidiasis, but was not detected in 6 cases of fungemia alone. CONCLUSIONS: Candida enolase antigenemia is a novel marker for invasive candidiasis. It may be a useful indicator of deep infection in patients with cancer and neutropenia and may complement the diagnostic usefulness of blood cultures.

[In vitro effect of amphotericin B on polymorphonuclear chemotaxis and large granular lymphocytes with natural killer activity]. / Effet in vitro de l'amphotéricine B sur le chimiotactisme des polynucléaires et des "large granular lymphocytes" à activité "natural killer".

Amphotericin B (AB) is known as an inhibitor of PMN chemotaxis. The chemotaxis of "large granular lymphocytes" (LGL) which are hypothesized to be involved in the antifungal defenses has been only recently investigated. Therefore we have studied the effect of AB on the LGL chemotaxis. LGL are prepared by centrifugation of peripheral blood non adherent cells on a discontinuous gradient of Percoll. They are more susceptible than PMN to the toxicity and chemotactic inhibition induced by colloidal suspension of AB Fungizone i.v. whereas the microparticular suspension has no effect. Deoxycholate (DOC) used for the AB solubilization is responsible at high doses of Fungizone i.v. (1 and 10(-1) mg/ml) of the toxic effect observed. The particular size seems to be also important. Morever at the therapeutic concentrations (2 to 4 X 10(-3) mg/ml) only the chemotaxis of PMN and LGL induced by FMLP is reduced whereas there is a stimulation of the PMN response to zymosan. The differences in the susceptibility of LGL and PMN to AB may explain the immunomodulation induced by this drug.