DNA based diagnostic for the quantification of sugarcane root DNA in the field.

Plant root systems play many key roles including nutrient and water uptake, interface with soil microorganisms and resistance to lodging. As for other crops, large and systematic studies of sugarcane root systems have always been hampered by the opaque and solid nature of the soil. In recent years, methods for efficient extraction of DNA from soil and for species-specific DNA amplification have been developed. Such tools could have potential to greatly improve root phenotyping and health diagnostic capability in sugarcane. In this paper, we present a fast, specific and efficient method for the quantification of sugarcane live root cells in soil samples. Previous studies were typically based on mass and length, so we established a calibration to convert root DNA quantity to live root mass. This diagnostic was validated on field samples and used to investigate the fate of the root system after harvest prior to regrowth of the ratoon crop. Two weeks after harvest, the sugarcane roots from the previous crop were still viable. This raises the question of the role that the root system of the harvested crop plays in the performance of the next crop and demonstrates how this test can be used to answer research questions.

Yield Loss in Cereals, Caused by Fusarium culmorum and F. pseudograminearum, Is Related to Fungal DNA in Soil Prior to Planting, Rainfall, and Cereal Type.

In southeastern Australia, Fusarium crown rot, caused by Fusarium culmorum or F. pseudograminearum, is an increasingly important disease of cereals. Because in-crop control options are limited, it is important for growers to know prior to planting which fields are at risk of yield loss from crown rot. Understanding the relationships between crown rot inoculum and yield loss would assist in assessing the risk of yield loss from crown rot in fields prior to planting. Thirty-five data sets from crown rot management experiments conducted in the states of South Australia and Victoria during the years 2005 to 2010 were examined. Relationships between Fusarium spp. DNA concentrations (inoculum) in soil samples taken prior to planting and disease development and grain yield were evaluated in seasons with contrasting seasonal rainfall. F. culmorum and F. pseudograminearum DNA concentrations in soil prior to planting were found to be positively related to crown rot expression (stem browning and whiteheads) and negatively related to grain yield of durum wheat, bread wheat, and barley. Losses from crown rot were greatest when rainfall during September and October (crop maturation) was below the long-term average. Losses from crown rot were greater in durum wheat than bread wheat and least in barley. Yield losses from F. pseudograminearum were similar to yield losses from F. culmorum. Yield loss patterns were consistent across experiments and between states; therefore, it is reasonable to expect that similar relationships will occur over broad geographic areas. This suggests that quantitative polymerase chain reaction technology and soil sampling could be powerful tools for assessing crown rot inoculum concentrations prior to planting and predicting the risk of yield loss from crown rot wherever this disease is an issue.

Supererogation and the profession of medicine.

In the light of increasing public mistrust, there is an urgent need to clarify the moral status of the medical profession and of the relationship of the clinician to his/her patients. In addressing this question, I first establish the coherence, within moral philosophy generally, of the concept of supererogation (the doing of more than one's duty). I adopt the notion of an act of "unqualified" supererogation as one that is non-derivatively good, praiseworthy, and freely undertaken for others' benefit at the risk of some cost to the agent. I then argue that committing oneself to the profession of clinical medicine is an act of this kind. This is the case, not because the aim of medicine is to help patients, but because of the open ended commitment of time and the vulnerability to the consequences of failure that the clinician must accept.

Prevention of nausea and vomiting after day case gynaecological laparoscopy. A comparison of ondansetron, droperidol, metoclopramide and placebo.

We have compared the efficacy of ondansetron, metoclopramide, droperidol and placebo in the prevention of postoperative nausea and vomiting in 118 day stay patients undergoing laparoscopic gynaecological procedures. All received a standardised general anaesthetic of fentanyl, propofol, nitrous oxide in oxygen and isoflurane. Three to five min before induction of anaesthesia, patients were allocated to receive ondansetron 4 mg, metoclopramide 10 mg, droperidol 1 mg or placebo in a randomised, double-blind manner. Visual analogue scores for nausea, the incidence of emetic episodes, and analgesic and antiemetic consumption were recorded for 48 h postoperatively. The scores for nausea were significantly lower in the ondansetron group (p < 0.01) compared with the other three groups at 1, 2 and 4 h after operation; thereafter there was no difference. The incidence of emesis was lower (p = 0.063) and time to first oral fluids was shorter (p < 0.05) in the ondansetron group. Oral analgesic requirements were significantly greater in the ondansetron group over the 48 h study period. Two patients, one each in the placebo and metoclopramide groups, had to remain in hospital overnight because of persistent emetic symptoms.

Sampling ryegrass to assess the risk of annual ryegrass toxicity.

Most stock losses caused by annual ryegrass toxicity occur because stockowners unknowingly allow their stock to graze annual ryegrass (Lolium rigidum) infected with the bacterium Clavibacter toxicus. To help stockowners avoid losses we have developed criteria for a testing service to determine the risk of poisoning before the pasture is grazed. Low, medium and high risk categories were selected using samples of dry, mature ryegrass seedheads collected by stockowners from untreated, infected pastures in South Australia. The proportion of toxic paddocks in each risk category over all the seasons tested was 11%, 32% and 76%, respectively, and these accounted for 7%, 14% and 79% of total stock losses. The proportion of paddocks in which stock were poisoned did not vary significantly between years, was not affected by variation in sample weight, and did not vary between South Australia and Western Australia.

Synergistic interaction between midazolam and propofol.

We gave either midazolam or propofol for induction of anaesthesia to 140 ASA I or II female patients (18-60 yr). ED50 values were obtained by probit analysis for three clinical end-points: loss of response to command; loss of eyelash reflex; failure to respond to application of an anaesthetic face mask delivering 1% isoflurane. Propofol ED50 values (95% confidence intervals) were 1.25 (0.99-1.48) mg kg-1, 1.61 (1.29-1.94) mg kg-1 and 1.51 (1.20-1.82) mg kg-1, respectively. ED50 values for midazolam were 0.26 (0.20-0.37) mg kg-1, 0.29 (0.23-0.47) mg kg-1 and 0.25 (0.20-0.32) mg kg-1, respectively. An additional 92 similar patients received one of nine dose combinations of midazolam and propofol for induction of anaesthesia, propofol being administered 2 min after midazolam. Success of induction was based on the clinical end-point of loss of response to command. Administration of 25% of the ED50 of midazolam followed by 50% of the ED50 of propofol resulted in loss of response to command in 50% of patients, while 50% of the ED50 of midazolam, followed by 25% of the ED50 of propofol had the same effect. A probit regression model specifying a synergistic interaction between midazolam and propofol fitted the data significantly better than a model specifying no interaction.

Effect of flumazenil on midazolam-induced amnesia.

We have studied the effect of i.v. flumazenil 0.01 mg kg-1 on the amnesia and sedation caused by midazolam 2 mg and 5 mg i.v. in volunteers in order to determine the relationship between the actions of the antagonist on these two effects. Midazolam caused dose-dependent central neural depression as assessed by critical flicker fusion frequency, and dose-dependent amnesia for word cards. In subjects given flumazenil 5 min after administration of midazolam, fusion frequency readings and memory were restored to levels comparable to those before midazolam administration. These two effects of flumazenil were similar in time course and extent, suggesting that they share the same mechanism of action. Flumazenil given alone had no effect on memory. The study has demonstrated anterograde amnesia following benzodiazepine administration and antagonism by flumazenil. There was neither retrograde amnesia nor retrograde antagonism of amnesia.

Effect of oral benzodiazepines on memory.

The effects of the oral administration of diazepam 5, 10 and 20 mg, flunitrazepam 0.5 and 1 mg and lorazepam 1, 2 and 4 mg on memory were studied in groups of healthy patients before surgery. The degree of sedation was noted also. A dose-related amnesic effect was produced by all the drugs, but this was not significant with diazepam 5 mg and lorazepam 1 mg. Larger doses of diazepam (10 and 20 mg) produced brief amnesia comparable to equivalent doses of flunitrazepam (0.5 and 1 mg). There was the same delay in the onset of amnesia after oral lorazepam 4 mg as when it was given i.v. and its effect lasted for at least 90 min after administration. In contrast to the effect of the same drugs given i.v., drowsiness and failure of recognition follow a similar time course.

Comparison of the actions of diazepam and lorazepam.

Diazepam and lorazepam differ in potency and in the time-course of their action. As a sedative, diazepam 10 mg is equivalent to lorazepam 2-2.5 mg. Diazepam is better absorbed after oral than after i.m. administrations but this does not apply to lorazepam. The clinical effect and amnesia begin more rapidly with diazepam, but last longer following lorazepam. Lorazepam is more effective than diazepam in blocking the emergence sequelae from ketamine. Lorazepam i.v. is followed by a lesser frequency of venous thrombosis.