In planta regulation of extension of an endophytic fungus and maintenance of high metabolic rates in its mycelium in the absence of apical extension

The fungus Neotyphodium lolii is an endophytic symbiont. It grows in the intercellular spaces of the perennial ryegrass Lolium perenne, producing secondary metabolites which enhance the fitness of the association over that of uninfected L. perenne. We report that the average number of hyphal strands in a given section of a leaf remains constant during the life of a leaf, indicating synchrony of leaf and hyphal extension, including cessation of hyphal extension when leaf extension ceases. We used a constitutively expressed reporter gene as an indicator of the mycelium's metabolic activity during and after hyphal extension. Reporter gene activity decreased when the mycelium stopped extending in liquid culture but not in planta. This indicates that in planta endophyte hyphae remain metabolically highly active when extension has ceased and throughout the life of the leaf they are colonizing. The behavior of the fungus in planta indicates the existence of signaling pathways which (i) synchronize the extension of leaf and hypha by regulating hyphal extension, (ii) suppress hyphal branching, and (iii) stop apical extension of fungal hyphae, without reducing the mycelium's metabolic activity. These signals may be crucial for the symbiosis, by allowing the endophyte to switch the focus of its metabolic activity from extension to the production of secondary metabolites.

Prevention of accidental childhood strangulation. A clinical study

Accidental strangulation is a preventable problem, and there is limited scientific understanding of its mechanism in children. If the amount of external pressure that occludes the airway can be determined, design changes may be made to allow for production of household objects that would break apart at safe pressure levels. A force gauge was applied to the suprahyoid region in 90 children under standardized anesthesia. Three blinded observers performed the study. The anesthesiologist maintained the airway and used a stethoscope to auscultate for breath sounds and monitor the CO2 curves to evaluate obstruction. The recorder noted the numbers from the gauge. A single observer applied the force gauge. Age was the most significant variable in occluding the airway. Obstruction appears to occur at the level of the larynx. Increased knowledge regarding the external pressure required for airway occlusion would allow for the design and manufacture of products with a reduced potential for accidental strangulation.

Prevention of accidental childhood strangulation: where is the site of obstruction?

BACKGROUND

Accidental strangulation is a preventable problem with limited scientific understanding in children. Children's clothing and household furniture have the potential to cause strangulation. Localizing the site of obstruction would provide understanding and insight to preventing this unfortunate event.

METHODS

While undergoing the application of pressure to the submental and suprahyoid region in eight patients flexible endoscopy was performed to evaluate the location of obstruction.

RESULTS

Submental pressure occluded the nasopharynx and oropharynx. Suprahyoid pressure occluded the larynx.

CONCLUSIONS

In suspension strangulation, airway obstruction appears to occur at the level of the larynx involving the epiglottis and the arytenoids. Increased knowledge regarding site of airway occlusion may help to decrease the hazard of accidental strangulation.

Endophytic fungi in indigenous Australasian grasses associated with toxicity to livestock

Grazing of Echinopogon spp. by livestock in Australia has caused symptoms similar to those of perennial ryegrass staggers. We observed an endophytic fungus in the intercellular spaces of the leaves and seeds of New Zealand and Australian specimens of Echinopogon ovatus. Culture of surface-sterilized seeds from New Zealand specimens yielded a slow-growing fungus. An examination in which immunoblotting and an enzyme-linked immunosorbent assay (ELISA) were used indicated that E. ovatus plants from Australia and New Zealand were infected with fungi serologically related to Neotyphodium lolii (the endophyte of perennial ryegrass) and other Epichloe and Neotyphodium spp. endophytic in pooid grasses. No lolitrems (the indole-diterpenoids implicated as the causative agents of perennial ryegrass staggers), peramine analogs, or ergot alkaloids were detected in the infected specimens by high-performance liquid chromatography or ELISA. However, in endophyte-infected E. ovatus plants from New Zealand, analogs of the indole-diterpenoid paxilline (thought to be a biosynthetic precursor of the lolitrems and related tremorgens) were detected by ELISA, and N-formylloline was detected by gas chromatography. Endophyte-free specimens of New Zealand E. ovatus did not contain detectable paxilline analogs or lolines and were more palatable than infected specimens to adults of the pasture pest Listronotus bonariensis (Argentine stem weevil). Hyphae similar to those of the E. ovatus endophyte were also found in herbarium specimens of Echinopogon nutans var. major, Echinopogon intermedius, Echinopogon caespitosus, and Echinopogon cheeli. This appears to be the first time that an endophytic Neotyphodium species has been identified in grasses endemic to New Zealand or Australia.

Low-dose sufentanil as a supplement to halothane/N2O anaesthesia in infants and children

Sufentanil as a supplement to halothane/N2O anaesthesia was evaluated in 32 unpremedicated infants and children age 6 months to 9 yr undergoing elective orthopaedic surgery. Patients were randomly assigned in a double-blind manner to receive one of four intravenous supplements: placebo, sufentanil 0.5, 1.0 or 1.5 micrograms.kg-1. Systolic arterial pressure (SAP), heart rate (HR) and end-tidal halothane concentration were recorded before and after induction, supplement administration, tracheal intubation, incision and every 15 min during the procedure. Venous catecholamine samples were obtained before and after incision. A pain score was assigned to the patients in the postanaesthesia care unit (PACU). Sufentanil at all three doses prevented increases in SAP and HR with intubation and incision, provided superior pain relief in the PACU and did not prolong wake-up time. Sufentanil 1.0 and 1.5 micrograms.kg-1 allowed for a reduction in the halothane requirements. Sufentanil 1.5 micrograms.kg-1 was associated with lower catecholamine levels than in the placebo group following incision. Sufentanil supplementation at 1.0 and 1.5 micrograms.kg-1 was associated with bradycardia and/or hypotension during induction and an increased incidence of vomiting during the first 24 hours postoperatively. One patient in the sufentanil 1.0 micrograms.kg-1 group whose surgical time was less than 45 min exhibited respiratory depression in the PACU requiring narcotic reversal. In conclusion, sufentanil 0.5 micrograms.kg-1 improved immediate postoperative pain relief and is acceptable as a supplement during halothane anasethesia in infants and children. The associated side effects of larger doses of sufentanil (1.0 and 1.5 micrograms.kg-1) make their use as a supplement to halothane anaesthesia unacceptable.

Synthesis of 2-Methylpyrrolo[1,2-a]pyrazin-1(2h)-one

The synthesis of 2-methylpyrrolo[1,2-a]pyrazin-1(2H)-one (2) present in the insect feeding deterrent peramine (1) through oxidation of the saturated lactam (3) is described. The preparation of the related 6- methyl-1H-pyrrolo[2,3-c]pyridin-7(6H)-one (12) through a Lewis-acid- catalysed cyclization of the amide acetal (7) is also described.

Selectivity of the Hydrogenation of 2',4',7-Tribenzyloxyisoflavone

Hydrogenation of 2',4',7-tribenzyloxyisoflavone (1) on a palladium/carbon catalyst gave nine products ranging from 4',7-dibenzyloxy-2'-hydroxyisoflavone (7) to 3,9-dihydroxypterocarpan (demethylmedicarpin ) (5) and 2',4',7-trihydroxyisoflavan (6), depending on the conditions. The benzyl groups of partially debenzylated products were located by 1H n.m.r.COSY experiments and chemical shift patterns.

The influence of induced hypotension and spine distraction on canine spinal cord blood flow

Deliberate hypotension is used in scoliosis surgery to reduce the need for blood transfusion and to improve operating conditions. There are concerns, however, that hypotension may decrease spinal cord blood flow (SCBF) and thereby predispose the spinal cord to ischemic injury, particularly when it is distracted during Harrington instrumentation. In a canine model, the mean arterial pressure (MAP) was reduced to 50% of the normotensive value with sodium nitroprusside and halothane to study its effects, with and without spinal distraction, on spinal cord blood flow measured by the hydrogen clearance technique. The induction of systemic hypotension resulted in a significant decrease in spinal cord blood flow from 15.7 +/- 1.1 ml/min/100 g (control) to 10.7 +/- 4.7 ml/min/100 g. This initial decrease in spinal cord blood flow returned to normotensive values by 35 minutes following the induction of hypotension, suggesting an autoregulatory effect. This indicates that the induction of deliberate hypotension to half its normotensive mean arterial pressure is associated with a significant decrease in spinal cord blood flow that returns to normotensive levels by 35 minutes. One and two centimeters of longitudinal distraction applied during systemic hypotension did not reduce spinal cord blood flow when it was applied at least 45 minutes after the hypotension was induced. Thus, when longitudinal stretch of a magnitude approximating that used clinically during Harrington instrumentation is applied in the presence of systemic hypotension, the normal SCBF is not reduced when the autoregulating system is functioning.(ABSTRACT TRUNCATED AT 250 WORDS)

Carotid injury and cerebral infarction in a revascularization hand injury case

A case of internal carotid artery thrombosis with cerebral infarction occurring in a patient with a massive hand injury is presented. In this case it can be postulated that the mechanism of injury was that of traction of the carotid during the patient's attempts at release of an immobilized extremity. Although the diagnosis of such an injury is difficult, the knowledge that such injuries occur and a suspicion of the examining physician at the time of the initial examination may help avoid such problems in the future.

Anesthetics as teratogens: nitrous oxide is fetotoxic, xenon is not

Exposure of pregnant rats to the anesthetic nitrous oxide on the ninth day of gestation causes fetal resorption, skeletal anomalies, and macroscopic lesions including encephalocele, anophthalmia, microphthalmia, and gastroschisis. The inert gas xenon, which has anesthetic properties similar to those of nitrous oxide, does not cause teratogenic effects under the same experimental conditions.

Urodynamic studies in anesthetized children

Urodynamic study was done on 31 neurologically normal children with urinary infection and/or severe voiding disturbances. The evaluation was performed with the child under anesthesia because awake testing proved unsatisfactory. Detrusor contraction occurred in 29 children under anesthesia and sufficient data were obtained to identify accurately patterns of dysfunction and to initiate therapy. A method for anesthetic neurourologic study using enflurane is presented, which permits reliable and reproducible urodynamic observations to be made in patients in whom awake investigations are incomplete or unsatisfactory.

The Absolute Configuration at C24 of the Ecdysteroids Dacrysterone, Pterosterone and Ponasterone C

The shielding values in 13C N.M.R. spectra of the ecdysteroids dacrysterone, pterosterone, and ponasterone C have been assigned, together with those for the 20,22- and 22,24-benzylidene acetal derivatives of the latter. From the N.M.R. data the C24 configuration of dacrysterone is assigned as 24R, while the 24s configuration is assigned to pterosterone and ponasterone C.