Components of male aggregation pheromone of strawberry blossom weevil, Anthonomus rubi herbst. (Coleoptera:Curculionidae)

The strawberry blossom weevil, Anthonomus rubi, is a major pest of strawberries in the United Kingdom and continental Europe. As part of a project to develop noninsecticidal control methods, the pheromone system of this species was investigated. Comparison of volatiles produced by field-collected, overwintering individuals of each sex led to identification of three male-specific compounds--(Z)-2-(3,3-dimethylcyclohexylidene)ethanol, (cis)-1-methyl-2-(1-methylethenyl)cyclobutaneethanol, and 2-(1-methylethenyl)-5-methyl-4-hexen-1-ol (lavandulol)--in amounts of 6.1, 1.2, and 0.82 microg/day/ male. The first two compounds are components of the aggregation pheromone of the boll weevil, Anthonomus grandis, grandlure II and grandlure I, respectively. Grandlure I was the (1R,2S)-(+) enantiomer and lavandulol was a single enantiomer, although the absolute configuration was not determined. Trace amounts of the other two grandlure components (Z)-(3,3-dimethylcyclohexylidene)acetaldehyde (grandlure III) and (E)-(3,3-dimethylcyclohexylidene)acetaldehyde (grandlure IV) were also detected. (E,E)-1-(1-Methylethyl)-4-methylene-8-methyl-2,7-cyclo-decadiene (germacrene-D), a known volatile from strawberry plants, Fragaria ananassa, was collected in increased amounts in the presence of pheromone-producing weevils. Male weevils only produced pheromone on F. ananassa and not on scented mayweed, Matracaria recutita, or cow parsley, Anthriscus sylvestris, although these are known food sources. In field trials using various combinations of synthetic grandlures I, II, III, and IV and lavandulol, significantly more weevils were caught in traps baited with blends containing grandlure I and II and lavandulol than in those baited with blends without lavandulol or unbaited controls. Addition of grandlure III and IV had no significant effect on attractiveness. Horizontal sticky traps were found to be more effective than vertical sticky traps or standard boll weevil traps. In mid-season females predominated in the catches, but later more males than females were trapped.

Expectant management of severe pre-eclampsia in the mid-trimester

OBJECTIVE

To determine maternal and perinatal outcomes with expectant management of severe pre-eclampsia in the mid-trimester, using a defined entry point.

DESIGN

Prospective case series. Thirty-nine women admitted from 24 to 27 week's gestation with severe pre-eclampsia, whose pregnancies were otherwise stable, were managed expectantly with careful clinical and biochemical monitoring of maternal and foetal status, together with careful blood pressure control, in a high-care obstetric ward. The aim was to safely prolong the pregnancies and thereby improve perinatal outcome.

RESULTS

Gestation was prolonged by a median of 12 (range 3--47) days, with greater periods gained at earlier gestations. The overall perinatal loss was 26% and the neonatal loss 17%. The rates of significant maternal complications were low.

CONCLUSION

Expectant management of selected women with severe pre-eclampsia from 24 to 27 weeks' gestation in a tertiary care unit is acceptably safe and improves perinatal outcome.

The influence of maternal age on pregnancy outcome in patients with early onset, severe pre-eclampsia

Pregnancy outcomes of women in three age categories, < or = 19, 20-34 and > or = 35 years, who underwent expectant management of early onset, severe pre-eclampsia were evaluated. This formed part of a prospective study involving 340 selected women from April 1992 to March 1997. Frequent monitoring of maternal and fetal status in a high-care obstetric ward was performed. Main outcome measures were major maternal complications, prolongation of gestation and perinatal outcome. Pregnancy was prolonged by a comparable number (10, 9 and 12) of days in the groups. Placental abruption was the most frequent major maternal complication, occurring more often in the youngest group (P=0.04). Women in this group also had the highest perinatal mortality and more often required anti-hypertensive medication at discharge (P<0.001). Younger women (< or = 19 years) appear to be at higher risk for maternal and perinatal complications.

Pregnancy outcome in women with prosthetic heart valves

The pregnancy outcome of 59 pregnancies in 38 women with prosthetic heart valves, managed at a tertiary referral centre from 1989-98 were reviewed. Ten women underwent valve replacement during pregnancy. The main outcome measures were major maternal complications and perinatal outcome. The maternal mortality rate for pregnancies following valve replacement surgery was 6.1%, with a 21% pregnancy loss before viability and a perinatal loss of 8%. Major morbidity in this group was as follows: haemorrhage 29.8%, cardiac failure 12.8%, thromboembolism 8.5%, infective endocarditis 6.4% and valve thrombosis 4.3%. No maternal mortality occurred among those who underwent valve replacement during pregnancy but their perinatal loss was 25%. We conclude that although maternal mortality and morbidity rates in women with prosthetic heart valves who became pregnant were high, the perinatal outcome was good except for women who underwent valve replacement during pregnancy who experienced a high perinatal loss rate.

Reversed end diastolic flow velocity in viable fetuses: is there time to wait for the effect of corticosteroids before delivery?

In severely pre-term, but viable fetuses with reversed end diastolic flow velocity in the umbilical artery, there is time for the effects of corticosteroids before delivery, unless fetal distress occurs.

Intracavity Beam Behavior in Hybrid Resonator Planar-Waveguide CO(2) Lasers

We describe a combined computer simulation and experimental investigation of the intracavity spatial beam profile characteristics of a planar-waveguide rf-excited CO(2) laser that incorporates a hybrid waveguide confocal unstable negative-branch resonator. The study includes results for the intracavity lateral beam intensity profile and output power of the laser as a function of resonator mirror misalignment. In addition, the behavior of the unstable resonator, observed experimentally and predicted by the simulation, in generating localized high intensity hot-spots when it is subjected to relatively large misalignment angles is reported.

Expectant management of early onset, severe pre-eclampsia: perinatal outcome

OBJECTIVE

To evaluate the perinatal outcome of expectant management of early onset, severe pre-eclampsia.

DESIGN

Prospective case series extending over a five-year period.

SETTING

Tertiary referral centre.

POPULATION

All women (n = 340) presenting with early onset, severe pre-eclampsia, where both mother and the fetus were otherwise stable.

METHODS

Frequent clinical and biochemical monitoring of maternal status with careful blood pressure control. Fetal surveillance included six-hourly heart rate monitoring, weekly Doppler and ultrasound evaluation of the fetus every two weeks. All examinations were carried out in a high care obstetric ward.

MAIN OUTCOME MEASURES

Prolongation of gestation, perinatal mortality rate, neonatal survival and major complications.

RESULTS

A mean of 11 days were gained by expectant management. The perinatal mortality rate was 24/1,000 (> or = 1,000 g/7 days) with a neonatal survival rate of 94%. Multivariate analysis showed only gestational age at delivery to be significantly associated with neonatal outcome. Chief contributors to neonatal mortality and morbidity were pulmonary complications and sepsis. Three pregnancies (0.8%) were terminated prior to viability and only two (0.5%) intrauterine deaths occurred, both due to placental abruption. Most women (81.5%) were delivered by caesarean section with fetal distress the most common reason for delivery. Neonatal intensive care was necessary in 40.7% of cases, with these babies staying a median of six days in intensive care.

CONCLUSION

Expectant management of early onset, severe pre-eclampsia and careful neonatal care led to high perinatal and neonatal survival rates. It also allowed the judicious use of neonatal intensive care facilities. Neonatal sepsis remains a cause for concern.

Expectant management of early onset, severe pre-eclampsia: maternal outcome

OBJECTIVE

To evaluate the safety and outcome of women undergoing expectant management of early onset, severe pre-eclampsia.

DESIGN

Prospective case series extending over a five-year period.

SETTING

Tygerberg Hospital, a tertiary referral centre.

POPULATION

All women (n = 340) presenting with early onset, severe pre-eclampsia, where both the mother and the fetus were otherwise stable.

METHODS

Frequent clinical and biochemical monitoring of maternal status, together with careful blood pressure control, in a high care obstetric ward.

MAIN OUTCOME MEASURES

Major maternal complications and prolongation of gestation.

RESULTS

Multigravid women constituted 67% of the group. Antenatal biochemistry was reassuring with some expected, but not severe, deteriorations. Twenty-seven percent of women experienced a major complication, but few had poor outcomes. No maternal deaths occurred. Most major complications resolved quickly, necessitating only three admissions (0.8%) to the intensive care unit. One woman required dialysis. Pregnancies were prolonged by a mean (median) number of 11 days (9) before delivery, with more time being gained at earlier gestations. The postpartum inpatient stay (89% < or =7 days, bearing in mind that 82% of women were delivered by caesarean section) was not extended.

CONCLUSION

Careful noninvasive management of early onset, severe pre-eclampsia in a tertiary centre can diminish and limit the impact of serious maternal complications. Valuable time to prolong the pregnancy and improve neonatal outcome is thereby gained.

Is the prophylactic administration of magnesium sulphate in women with pre-eclampsia indicated prior to labour?

OBJECTIVE

To determine whether prophylactic magnesium sulphate is necessary to prevent eclampsia and associated complications among women with pre-eclampsia prior to labour.

DESIGN

Case series.

SETTING

Tertiary referral centre.

POPULATION

Three hundred and eighteen women with pre-eclampsia (blood pressure > or = 140/90 mmHg and > or = 2+ proteinuria) who were not in labour or for planned induction thereof and had not received magnesium sulphate during transfer.

METHODS

Clinical evaluation of the pregnant women with careful blood pressure control. Magnesium sulphate was withheld even in the presence of imminent eclampsia. During labour, the option of magnesium sulphate prophylaxis was left to the clinician, but magnesium sulphate was administered in cases of eclampsia.

MAIN OUTCOME MEASURES

Eclampsia and related complications.

RESULTS

Five women (1.5%) developed eclampsia, although none developed related complications. Women presented at an early gestational age (mean 30 weeks), with high blood pressure, often suffering from headaches. Twenty pregnancies were terminated prior to viability, of which half were terminated for maternal reasons. Ten intrauterine deaths occurred. Most often fetal distress (38.6%) initiated the delivery process, which was mainly by caesarean section (68.5%). With the exception of epigastric discomfort, symptoms and signs of imminent eclampsia decreased after admission. Blood pressure values were significantly lower at delivery although biochemistry results deteriorated from admission to delivery.

CONCLUSION

In women with pre-eclampsia prior to labour, where blood pressure control was carefully applied but magnesium sulphate not given, the eclampsia rate was low and eclampsia did not appear to worsen the existing prognosis for mother or fetus.

Nifedipine or prazosin as a second agent to control early severe hypertension in pregnancy: a randomised controlled trial

OBJECTIVE

To determine whether nifedipine or prazosin is the more appropriate second-line antihypertensive agent in pregnancy.

DESIGN

Randomised controlled trial.

SETTING

Tygerberg Hospital, a tertiary referral centre.

POPULATION

Women with early, severe pre-eclampsia or hypertension in pregnancy, whose blood pressure could not be adequately controlled by methyldopa 2 g/day, but were otherwise stable.

METHODS

Nifedipine or prazosin were given and increased as necessary in a stepwise fashion. Once the maximum dose was reached, the other drug was added in a crossover pattern. Failure to control blood pressure, or the onset of maternal/fetal complications were indications for delivery. Patients reaching a minimum gestation of 34 weeks without complications were delivered electively.

MAIN OUTCOME MEASURES

Antenatal days gained; major maternal complications and perinatal survival.

RESULTS

Days gained on the second antihypertensive agent did not differ significantly (P = 0.9), while more days were gained using nifedipine as the crossover 'third agent' (P = 0.01). In the nifedipine group better renal function was recorded, but more cases with isolated low platelet counts occurred. More cases of pulmonary oedema as well as more nonviable mid-trimester and third trimester intrauterine deaths occurred in the prazosin group.

CONCLUSION

Nifedipine and prazosin as second agents allowed comparable amounts of time to be gained, although this changed when used as crossover third-line agents. The efficacy and safety of nifedipine in this study are consistent with the results of other studies. A greater number of intrauterine deaths occurred in the prazosin group.

Interpretation of thermodynamic non-ideality in sedimentation equilibrium experiments on proteins

This investigation re-examines theoretical aspects of the allowance for effects of thermodynamic non-ideality on the sedimentation equilibrium distribution for a single macromolecular solute, and thereby resolves the question of the constraints that pertain to the definition of the activity coefficient term in the basic sedimentation equilibrium expression. Sedimentation equilibrium results for ovalbumin are then presented to illustrate a simple procedure for evaluating the net charge (valence) of a protein from the magnitude of the second virial coefficient in situations where the effective radius of the protein can be assigned. Finally, published sedimentation equilibrium results on lysozyme are reanalysed to demonstrate the feasibility of employing the dependence of the second virial coefficient upon ionic strength to evaluate both the valence and the effective radius of the non-interacting solute.

The three-dimensional structure of a Plasmodium falciparum cyclophilin in complex with the potent anti-malarial cyclosporin A

Cyclosporin A (CsA) is a potent anti-malarial compound in vitro and in vivo in mice though better known for its immunosuppressive properties in humans. Crystal structures of wild-type and a double mutant Plasmodium falciparum cyclophilin (PfCyP19 and mPfCyP19) complexed with CsA have been determined using diffraction terms to a resolution of 2.1 A (1 A=0.1 nm). The wild-type has a single PfCyP19/CsA complex per asymmetric unit in space group P1 and refined to an R-work of 0.15 and R-free of 0.19. An altered cyclophilin, with two accidental mutations, Phe120 to Leu in the CsA binding pocket and Leu171 to Trp at the C terminus, presents two complexes per asymmetric unit in the orthorhombic space group P2(1)2(1)2. This refined to an R-work of 0.18 and R-free 0.21. The mutations were identified from the crystallographic analysis and the C-terminal alteration helps to explain the different crystal forms obtained. PfCyP19 shares approximately 61 % sequence identity with human cyclophilin A (hCyPA) and the structures are similar, consisting of an eight-stranded antiparallel beta-barrel core capped by two alpha-helices. The fold creates a hydrophobic active-site, the floor of which is formed by side-chains of residues from four antiparallel beta-strands and the walls from loops and turns. We identified C-H.O hydrogen bonds between the drug and protein that may be an important feature of cyclophilins and suggest a general mode of interaction between hydrophobic molecules. Comparisons with cyclophilin-dipeptide complexes suggests that a specific C-H.O hydrogen bonding interaction may contribute to ligand binding. Residues Ser106, His99 and Asp130, located close to the active site and conserved in most cyclophilins, are arranged in a manner reminiscent of a serine protease catalytic triad. A Ser106Ala mutant was engineered to test the hypothesis that this triad contributes to CyP function. Mutant and wild-type enzymes were found to have similar catalytic properties.

Risk factors for and perinatal mortality of abruptio placentae in patients hospitalised for early onset severe pre-eclampsia - a case controlled study

We set out to determine which patients admitted for expectant management of early onset severe pre-eclampsia develop abruptio placentae and to compare the perinatal mortality rate of patients who developed abruptio placentae with those who did not have this complication. This was a case controlled study, using gestational age at delivery to select a control group for 69 patients who developed abruptio placentae. The only significant difference on admission was the higher uric acid levels in patients who developed abruptio placentae. Mean admission to delivery intervals were 11.9 and 8.8 days for the control and abruption groups respectively (P = 0.0083). Fifty-eight per cent of the babies in the abruptio placentae group developed late decelerations, as determined by fetal heart rate monitoring compared with 32% in the control group. Lactate dehydrogenase levels before delivery were significantly higher in the abruption group, but it only became elevated shortly before delivery and in the minority of cases. There were two intrauterine and four neonatal deaths in the abruption group and two neonatal deaths in the control group. Late decelerations detected by frequent fetal heart rate monitoring in patients with early onset severe pre-eclampsia is the only early warning of abruptio placentae.

Reassessment of the calibration constant for the IAsys biosensor

A magnitude of 50 are s ng-1 mm2 has been determined for the calibration constant relating biosensor response to the amount of protein bound to the sensor surface of an IAsys cuvette. These studies entailed enzymatic assessment of the extent of lactate dehydrogenase depletion in the liquid phase arising from enzyme binding to a carboxymethyldextran-coated sensor surface, and also estimation of a maximum biosensor response for the electrostatic interaction of ovalbumin with an aminosilane-coated sensor surface. The latter results required correction for contributions to biosensor response resulting from changes in the refractive index of the liquid phase effected by high protein concentrations.

The crystal structure of Escherichia coli class II fructose-1, 6-bisphosphate aldolase in complex with phosphoglycolohydroxamate reveals details of mechanism and specificity

The structure of a class II fructose-1,6-bisphosphate aldolase in complex with the substrate analogue and inhibitor phosphoglycolohydroxamate (PGH) has been determined using X-ray diffraction terms to a resolution of 2.0 A (1 A=0.1 nm). The crystals are trigonal, space group P3121 with a=b=78.24 A, c=289.69 A. The asymmetric unit is a homodimer of (alpha/beta)8 barrels and the model has refined to give R-work 19.2 %, R-free (based on 5 % of the data) 23.0 %. PGH resembles the ene-diolate transition state of the physiological substrate dihydroxyacetone phosphate. It is well ordered and bound in a deep polar cavity at the C-terminal end of the (alpha/beta)8 barrel, where it chelates the catalytic zinc ion using hydroxyl and enolate oxygen atoms. Trigonal bipyramidal coordination of the zinc ion is completed by three histidine residues. The complex network of hydrogen bonds at the catalytic centre is required to organise the position of key functional groups and metal ion ligands. A well-defined monovalent cation-binding site is observed following significant re-organisation of loop structures. This assists the formation of a phosphate-binding site on one side of the barrel that tethers PGH in the catalytic site. The positions of functional groups of substrate and putative interactions with key amino acid residues are identified. Knowledge of the complex structure complements the results of spectroscopic and site-directed mutagenesis studies, and contributes to our understanding of the mechanism and substrate specificity of this family of enzymes. A reaction mechanism distinct from that proposed for other class II aldolases is discussed. The results suggest that the class II aldolases should be sub-divided into two groups on the basis of both distinct folds and mechanism.

The high-resolution crystal structure of the molybdate-dependent transcriptional regulator (ModE) from Escherichia coli: a novel combination of domain folds

The molybdate-dependent transcriptional regulator (ModE) from Escherichia coli functions as a sensor of molybdate concentration and a regulator for transcription of operons involved in the uptake and utilization of the essential element, molybdenum. We have determined the structure of ModE using multi-wavelength anomalous dispersion. Selenomethionyl and native ModE models are refined to 1. 75 and 2.1 A, respectively and describe the architecture and structural detail of a complete transcriptional regulator. ModE is a homodimer and each subunit comprises N- and C-terminal domains. The N-terminal domain carries a winged helix-turn-helix motif for binding to DNA and is primarily responsible for ModE dimerization. The C-terminal domain contains the molybdate-binding site and residues implicated in binding the oxyanion are identified. This domain is divided into sub-domains a and b which have similar folds, although the organization of secondary structure elements varies. The sub-domain fold is related to the oligomer binding-fold and similar to that of the subunits of several toxins which are involved in extensive protein-protein interactions. This suggests a role for the C-terminal domain in the formation of the ModE-protein-DNA complexes necessary to regulate transcription. Modelling of ModE interacting with DNA suggests that a large distortion of DNA is not necessary for complex formation.

Two crystal forms of ModE, the molybdate-dependent transcriptional regulator from Escherichia coli

The molybdenum-responsive ModE regulatory protein from Escherichia coli has been purified and used in crystallization trials. Two crystal forms have been observed. Form I is tetragonal, P41212 (or enantiomorph), with a = b = 72.3, c = 246.2 A and diffracts to medium resolution. Form II is orthorhombic, P21212, with a = 82.8, b = 127.9, c = 64.0 A and diffraction has been observed beyond 2.8 A resolution. Structural analysis, in combination with ongoing biochemical characterization, will assist the elucidation of the structure-activity relationship in regulating the uptake of molybdate in bacteria.

Crystallization and preliminary X-ray diffraction studies of 6-phosphogluconate dehydrogenase from Lactococcus lactis

6-Phosphogluconate dehydrogenase is one of the seven enzymes involved in the pentose phosphate pathway. Crystals of a mammalian and a protozoan enzyme have been obtained previously and structures determined. It is reported here that a bacterial 6-phosphogluconate dehydrogenase, from Lactococcus lactis, has been purified and used in crystallization trials. Large prisms suitable for a detailed structural analysis have been obtained and characterized as orthorhombic, space group F222, with a = 70.4, b = 105.7, c = 474.6 A. Diffraction has been observed to 2.2 A resolution using synchrotron radiation. Structural analysis, in combination with ongoing biochemical characterization, will assist the elucidation of the structure-activity relationships of this enzyme.

Potential of biosensor technology for the characterization of interactions by quantitative affinity chromatography

This review places the characterization of interactions by biosensor technology in the broader context of their study by quantitative affinity chromatography. The general reluctance to consider biosensor-based characterization as a form of quantitative affinity chromatography on the grounds of a difference in aims of the two techniques reflects a mistaken belief that BIAcore and IAsys studies characterize the kinetics of the chemical reaction responsible for biospecific adsorption of a soluble reactant to an immobilized form of its affinity partner. It now transpires that the association and dissociation rate constants thereby determined refer to thermodynamic characterization of biospecific adsorption in terms of a single-phase model in which affinity sites are distributed uniformly throughout the liquid-phase volume accessible to the partitioning reactant--the model used for characterization of biospecific adsorption by quantitative affinity chromatography. In that light the most important attribute of biosensor technology is its potential for thermodynamic characterization of biospecific adsorption by virtue of its ability to monitor complex formation directly; and hence its potential for the characterization of interactions with affinities that are too strong for study by forms of quantitative affinity chromatography that monitor complex formation on the basis of reactant depletion from the liquid phase. Kinetic as well as thermodynamic analyses of biosensor data are described for attainment of that potential.

Theoretical and experimental considerations of the pseudo-first-order approximation in conventional kinetic analysis of IAsys biosensor data

The validity of the conventional interpretation of IAsys biosensor profiles in terms of pseudo-first-order kinetic behavior is subjected to closer scrutiny by its application to simulated data for low- and high-affinity interactions between ligate and immobilized ligand. As might reasonably have been expected, analysis of the simulated data for the low-affinity system (association equilibrium constant of 10(5) M-1) in such terms returned the input association and dissociation rate constants (10(3) M-1 s-1 and 10(-2) s-1, respectively)-a consequence of essential compliance with the assumed constancy of ligate concentration in the liquid phase. For the high-affinity interaction (ka = 10(5) M-1 s-1, kd = 10(-2) s-1, KAX = 10(7) M-1) the ligate concentration was depleted by up to 35%, and hence its assumed constancy was clearly an untenable approximation. Whereas no symptomatic evidence of such violation (apart from the return of incorrect estimates of ka and kd) was evident from pseudo-first-order kinetic analysis of the adsorption profiles, the corresponding analysis of desorption profiles was more informative in that the data deviated demonstrably from pseudo-first-order kinetic behavior. A second-order kinetic analysis was therefore developed and shown to be applicable to adsorption and desorption profiles, irrespective of the validity or otherwise of the pseudo-first-order kinetic approximation. Experimental results obtained for the interaction of histidine-rich glycoprotein with immobilized IgG were then used to illustrate various features of the pseudo-first-order and second-order kinetic analyses, and to determine from the second-order analysis an association equilibrium constant of 2 x 10(8) M-1, which is 20-fold greater than the value obtained by interpretation of the profiles in terms of pseudo-first-order kinetic behavior.