Production of (5R,6S)-6-acetoxy-5-hexadecanolide, the mosquito oviposition pheromone, from the seed oil of the summer cypress plant, Kochia scoparia (Chenopodiaceae)

The oviposition pheromone for the pathogen-vectoring mosquitoes in the genus Culex (Diptera: Culicidae), that is, (5R, 6S)-6-acetoxy-5-hexadecanolide, is efficiently synthesized, in admixture with the inactive (5S,6R) enantiomer ( approximately 33% w/w), from the fixed oil extracted from the seeds of the summer cypress plant, Kochia scoparia (Chenopodiaceae), cultivated on an industrial scale. Oviposition bioassays using gravid females of Culex quinquefasciatus, a vector of filariasis in human beings, showed that the product was attractive, with activity comparable to that of a pure synthetic sample containing the same amount of the active enantiomer. Production of the pheromone in the form of a biologically active crude material via a cheap and renewable plant suitable for development as a new industrial crop provides the basis for control of Cx. quinquefasciatus and other congeneric vectors of pathogens in resource-poor areas of the world.

A survey of epidural analgesia for labour in the United Kingdom

A postal survey of obstetric units throughout the UK was conducted to obtain information about the provision of epidural analgesia for labour. Ninety per cent of units offered a 24-h epidural service and the average epidural rate was 24%. The most commonly administered epidural test dose was 3 ml of bupivacaine 0.5% and bupivacaine 0. 25% was most often used as the initial epidural top-up. Continuous infusions of low-dose bupivacaine and opioid mixtures were the most popular method of maintenance epidural analgesia. Twenty-four per cent of units offered combined spinal-epidural analgesia in addition to standard epidural analgesia. Midwives played a prominent role in the administration of epidural bolus top-ups and also in the assessment and maintenance of continuous epidural infusions.

Diagnostic indicators in the early recognition of severe cocaine intoxication

Acute cocaine intoxication is an ever increasing problem in the United Kingdom. Aggressive resuscitation linked to early diagnosis is essential in preventing death. Three cases of severe cocaine toxicity are presented to highlight certain diagnostic indicators in recognising the condition in patients presenting in a collapsed state to the accident and emergency department. Acidosis was a striking feature. The acute management of such patients is supportive and should involve methods to minimize continuing absorption.

Does midwifery-led intrapartum care require anaesthetic services?

The report of the Expert Maternity Group 'Changing Childbirth' (The Cumberlege Report) advocates a greater role for midwives in the care of the low risk pregnant woman, and has promoted much discussion about the future development of maternity services in the UK. At Leicester Royal Infirmary NHS Trust the 'Home from Home' delivery scheme provides midwifery-led antenatal and intrapartum care of women with uncomplicated pregnancies. We have performed a retrospective review of the requirements for anaesthetic services in this unit. During the 12 month review period 1610 women were admitted to the 'Home from Home' delivery scheme in labour. One hundred and eighty one women subsequently received anaesthetic intervention. Of this group, 137 (77.0%) required an epidural, 17 (9.6%) a spinal, 18 (10.1%) a general anaesthetic, 5 (2.8%) an epidural and a general anaesthetic and 1 (0.6%) an epidural and a spinal. Our results demonstrate that low risk pregnant women in labour being cared for in a midwifery led unit have a considerable need for anaesthesia and analgesia.

The aphid sex pheromone cyclopentanoids: synthesis in the elucidation of structure and biosynthetic pathways

Identification of a range of aphid sex pheromones as comprising the cyclopentanoids (4aS,7S,7aR)-nepetalactone, (1R,4aS,7S,7aR)-nepetalactol and the (1S)- and (1R,4aR,7S,7aS)-nepetalactols required samples authenticated by 1H and 13C NMR. These and related compounds were provided by small scale synthesis and extraction from plants in the genus Nepeta (Lamiaceae). The subsequent discovery that the synthetic sex pheromones could attract males, and also parasitic wasps that attack aphids, has created a need for large scale syntheses of the cyclopentanoids. This is afforded by cyclisation of the 8-oxo-1-enamine of citronellal as originally developed by Schreiber and co-workers (1986). Investigation into the biosynthesis of the cyclopentanoids by plants for exploiting aphid sex pheromones in crop protection by means of molecular biology required synthesis of putative biosynthetic intermediates, some with radioactive isotopic labelling, particularly 8-oxidised monoterpene alcohols and aldehydes.

Purification and characterization of an acyclic monoterpene primary alcohol:NADP+ oxidoreductase from catmint (Nepeta racemosa)

A soluble monoterpene primary alcohol:NADP+ oxidoreductase has been purified to apparent homogeneity from leaves of the catmint, Nepeta racemosa. The purified enzyme consisted of two polypeptides, with molecular masses of 42,000 and 40,000 Da, and contained zinc ions. A number of monoterpene alcohols (geraniol, nerol, citronellol, and their hydroxylated derivatives) were substrates, but the enzyme was inactive toward ethanol. The enzyme required NADP(H) as cofactor, with NAD(H) ineffective. Gas chromatographic and coupled mass spectrometric analysis of the reaction products showed that 10-hydroxygeraniol and 10-hydroxynerol were oxidized by the enzyme in the presence of NADP+, at both C-1 and C-10. These results are consistent with a role for this enzyme in the biosynthesis of iridoid monoterpenes.

Convective warming after hypothermic cardiopulmonary bypass

In a randomized, controlled study, we found that convective warming after hypothermic cardiopulmonary bypass did not accelerate the rate of warming of the body core or the time to tracheal extubation. The relationship between body core and shell temperature, however, was affected. In all patients inadequate time spent rewarming on cardiopulmonary bypass prolonged body core warming time and time to tracheal extubation. Rate of warming of body core was inversely related to body mass index. Convective warming was delivered using BairHugger (Augustine Medical Inc., MN, USA) and Warm Touch (Mallinckrodt Medical UK Ltd, Northampton, UK) blankets. There was no difference between the performance of each blanket when powered by the BairHugger 500 power unit set at its medium setting of 38 degrees C, and when chest drain and radial artery cannulation sites were left exposed for observation.

Cytochrome P-450-catalysed monoterpenoid oxidation in catmint (Nepeta racemosa) and avocado (Persea americana); evidence for related enzymes with different activities

A cytochrome P-450 present in ripening avocado (Persea americana) fruit mesocarp (CYP71A1) had previously been shown to metabolize the monoterpenoids nerol and geraniol (Hallahan et al. (1992) Plant Physiol. 98, 1290-1297). Using DNA encoding CYP71A1 as a hybridization probe, we have shown by Southern analysis that a related gene is present in the catmint, Nepeta racemosa. RNA blot analysis, together with Western analysis of catmint leaf polypeptides using avocado cyt P-450 antiserum, showed that a closely related gene is expressed in catmint leaves. Cytochrome P-450 in catmint microsomes catalysed the specific hydroxylation of nerol and geraniol at C-10, whereas avocado CYP71A1, in either avocado microsomes or heterologously expressed in yeast, catalysed 2,3- or 6,7-epoxidation of these substrates. These results suggest that orthologous genes of the CYP71 family are expressed in these two plant species, but catalyse dissimilar reactions with monoterpenoid substrates.

The role of soda lime during administration of inhaled nitric oxide

We have studied the ability of three commercially available preparations of soda lime to act as nitrogen dioxide scavengers during administration of inhaled nitric oxide. Soda lime, with a green to brown colour change (indicator = potassium permanganate), markedly reduced concentrations of nitrogen dioxide, but also markedly reduced inhaled concentrations of nitric oxide. The other varieties of soda lime, with colour changes from pink to white (indicator = kenazol yellow) or white to violet (indicator = ethyl violet), produced little effect on concentrations of nitrogen dioxide. None of the above soda limes can be recommended for use as a nitrogen dioxide scavenger during administration of inhaled nitric oxide.

Synthesis of glucosinolate precursors and investigations into the biosynthesis of phenylalkyl- and methylthioalkylglucosinolates

The alkenyl and aromatic glucosinolates in oilseed rape (Brassica napus) are biosynthesized from chain-extended homologues of protein amino acids, including methionine and phenylalanine. Homologues of these two amino acids, homophenylalanine (2-amino-4-phenylbutyric acid) and dihomomethionine (2-amino-6-methylthiohexanoic acid) were synthesized both with and without a 1-14C label. Microsomal preparations from oilseed rape leaves were shown to contain enzyme systems which metabolize these compounds, with loss of 14CO2, and produce the aldoxime intermediates possible in the biosynthetic pathway utilizing homophenylalanine. These were characterized by comparison with authenticated synthetic compounds. Potential intermediates on the pathway between homophenylalanine and its corresponding aldoxime, the N-hydroxyamino- and the oximino acids, were synthesized and their possible role in the pathway investigated.