A role for glutathione transferases functioning as glutathione peroxidases in resistance to multiple herbicides in black-grass

Black-grass (Alopecurus myosuroides) is a major weed of wheat in Europe, with several populations having acquired resistance to multiple herbicides of differing modes of action. As compared with herbicide-susceptible black-grass, populations showing herbicide cross-resistance contained greatly elevated levels of a specific type I glutathione transferase (GST), termed AmGST2, but similar levels of a type III GST termed AmGST1. Following cloning and expression of the respective cDNAs, AmGST2 differed from AmGST1 in showing limited activity in detoxifying herbicides but high activities as a glutathione peroxidase (GPOX) capable of reducing organic hydroperoxides. In contrast to AmGST2, other GPOXs were not enhanced in the herbicide-resistant populations. Treatment with a range of herbicides used to control grass weeds in wheat resulted in increased levels of hydroperoxides in herbicide-susceptible populations but not in herbicide-resistant plants, consistent with AmGST2 functioning to prevent oxidative injury caused as a primary or secondary effect of herbicide action. Increased AmGST2 expression in black-grass was associated with partial tolerance to the peroxidizing herbicide paraquat. The selective enhancement of AmGST2 expression resulted from a constitutively high expression of the respective gene, which was activated in herbicide-susceptible black-grass in response to herbicide safeners, dehydration and chemical treatments imposing oxidative stress. Our results provide strong evidence that GSTs can contribute to resistance to multiple herbicides by playing a role in oxidative stress tolerance in addition to detoxifying herbicides by catalysing their conjugation with glutathione.

Tackling the emerging pandemic of non-communicable diseases in sub-Saharan Africa: the essential NCD health intervention project

There is evidence that the prevalence of certain non-communicable diseases, such as diabetes and hypertension, is increasing rapidly in parts of sub-Saharan Africa. Others, such as asthma and epilepsy, are known to be common but to be poorly managed. This paper describes a project, funded by the Department for International Development of the British Government, which aims to provide costed and evaluated treatment packages for use at primary health care level, methods and materials for evaluating the quality of non-communicable disease care, and a protocol for the assessment for national opportunities for the prevention of hypertension, heart disease and diabetes. Methods are being developed and piloted in urban and rural Tanzania and Cameroon.

An inverse relation between blood pressure and birth weight among 5 year old children from Soweto, South Africa

STUDY OBJECTIVE

To examine the relation between birth weight and blood pressure at 5 years in a cohort of South African children.

DESIGN

Prospective cohort study.

PARTICIPANTS

849 five year old children.

SETTING

Soweto, a sprawling urban area close to Johannesburg, South Africa, which was a designated residential area for people classified as "black" under apartheid legislation.

MAIN RESULTS

Systolic blood pressure at 5 years was inversely related to birthweight (r = -0.05, p = 0.0007), independent of current weight, height, gestational age, maternal age or socioeconomic status at 5 years. There was no relation between birth weight and diastolic blood pressure. After adjusting for current weight and height, there was a mean decline in systolic blood pressure of 3.4 mm Hg (95% confidence intervals 1.4, 5.3 mm Hg) for every 1000 g increase in birth weight.

CONCLUSIONS

These data from a disadvantaged urbanised community in Southern Africa extend the reported observations of an inverse relation between birth weight and systolic blood pressure. The study adds to the evidence that influences in fetal life and early childhood influence systolic blood pressure. Further research is required to assess whether efforts to reduce the incidence of low birthweight babies will attenuate the prevalence of hypertension in future generations.

A prospective controlled trial of the efficacy of isopropyl alcohol wipes before venesection in surgical patients

It has previously been suggested that skin preparation before venesection with antiseptic agents is unnecessary. However thousands of doctors and medical students continue to use isopropyl alcohol (IPA) swabs for venesection, at an estimated cost of 10,000 P per annum in a 500 bed hospital. An audit of IPA swab use among junior doctors and medical students at our institution was undertaken; 76% of doctors and 100% of medical students routinely prepared the skin with alcohol before venesection and only one used the swabs correctly. A randomised single-blind controlled trial was conducted of IPA versus no IPA skin preparation before venesection. There were 194 patients in the study, 93 in the IPA group and 101 controls. There was no statistical difference with respect to complications at the venepuncture site between the two groups.

Speed-dependent responses in V5: A replication study

In a previous paper, we used fMRI to examine motion-sensitive responses in human area V5 as a function of stimulus speed. As predicted by electrophysiological findings, we observed optimal responses at intermediate speeds of around 7 to 30 degrees /s. These results revealed a nonlinear (inverted "U") dependency on speed that was also evident in V3a. In this paper we repeated the experiment using an improved stimulus and a larger range of speeds. We replicated our previous findings and extended our characterization of speed-dependent responses: Optimal responses were seen in V5 at speeds of 4 and 8 degrees /s and in V3a at speeds of 4 to 16 degrees /s. We were also able to show an interaction between speed (fast vs slow) and contrast (color > luminance) in V5. This interaction was anticipated on the basis of the different properties of the geniculate and extrageniculate inputs to V5. Finally, we were also able to demonstrate an interaction between motion (moving vs stationary) and contrast (color > luminance) in V4. This suggests that for V4, color-specific responses are augmented in the context of motion; or equivalently, that color contrast enhances any motion-sensitive responses in V4.

Quantification of neuromotor function for detection of the effects of manganese

The effect of low level exposure to manganese (Mn) was examined in 297 subjects from southwest Quebec. Blood manganese (MnB) levels as well as other possibly relevant variables were obtained. We tested equipment and analysis procedures that we have developed to quantify aspects of motor function thought to be affected by exposure to toxins, in particular, rapid alternating movements, rapid and precise pointing movements, and tremor. (1) The eurythmokinesimeter measures timing and precision of contacts between a hand-held stylus and a pair of metal targets (proximal/distal). This roughly approximates the finger-to-nose test of the UPDRS. Characteristics quantifying speed, precision and regularity of the movements were calculated, as well as multiple contacts due to tremor and an index based on Fitts' Law eliminating the effect of the trade-off between speed and precision. (2) The diadochokinesimeter accurately measures rapid rotation of the forearms (pronation/supination). Characteristics quantifying the range, speed, period, shape and regularity of the oscillatory movements were calculated, as well as the smoothness of the movement on a fine scale and the coordination between the two hands. (3) Postural tremor of the arm and hand was measured using the accelerometry-based "TREMOR" system of Danish Product Development. We used the amplitude and frequency characteristics provided by the TREMOR system: intensity, center frequency, dispersion and harmonic index. Previous studies have shown that these tests are sufficiently sensitive to detect small differences in performance of different groups of subjects, with indications that some characteristics are also specific to particular conditions. In this study, significant though small effects related to age and gender were found in many of the characteristics. When effects of other variables are removed, low-level exposure to Mn was found to be associated with a decrease in ability to perform regular, rapid and precise pointing movements, a decrease in ability to attain high maximum rotation speeds in rapid alternating movements, and an increase in regularity of tremor oscillations. Moreover, the effects are age-related for levels of MnB 7.5, micrograms/L.

Manganese neurotoxicity, a continuum of dysfunction: results from a community based study

Excessive manganese (Mn) has been associated with neurobehavioral deficits and neurological and/or neuropsychiatric illness, but the level at which this metal can cause adverse neurotoxic effects, particularly with long-term exposure, is still unknown. The objective of the present study was to assess nervous system functions in residents exposed to manganese from a variety of environmental sources. A random stratified sampling procedure was used to select participants; persons with a history of workplace exposure to Mn and other neurotoxic substances were excluded. A self-administered questionnaire provided data on socio-demographic variables. Blood samples were analyzed for total manganese (MnB), lead, mercury and serum iron. Nervous system assessment included computer and hand-administered neurobehavioral tests, computerized neuromotor tests, sensory evaluation and a neurological examination. The present analyses include 273 persons (151 women and 122 men); MnB range: 2.5 micrograms/L-15.9 micrograms/L (median: 7.3 micrograms/L). Multivariate analyses were used and neuro-outcomes were examined with respect to MnB, taking into account potential confounders and covariables. Results were grouped according to neurofunctional areas and MANOVA analyses revealed that higher MnB (7.5 micrograms/L) was significantly associated with changes in coordinated upper limb movements (Wilks' lambda = 0.92; p = 0.04) and poorer learning and recall (men: Wilks' lambda = 0.77; p = 0.002; women: Wilks' lambda = 0.86; p = 0.04). Further analyses revealed that with increasing log MnB (Simple regression: p < 0.05) performance on a pointing task was poorer, frequency dispersion of hand-arm tremor decreased, while harmonic index increased, and the velocity of a pronation/supination arm movement was slower. An Mn-age interaction was observed for certain motor tasks, with the poorest performance observed among those _50 y and in the higher MnB category. Differences between genders suggest that men may be at greater risk than women, although effects were also observed in women. These findings are consistent with the hypothesis that Mn neurotoxicity can be viewed on a continuum of dysfunction, with early, subtle changes at lower exposure levels.

Risk: a media perspective

The joumalist's quest for stories and the media's business needs pose problems for those who work in radiation protection. Accidents are news; routine operations are not. Relations with journalists have been damaged by dishonesty about radiation. Secrecy, a legacy of the atomic bomb, still persists throughout the nuclear industry and distorts public debate. Examples are given. There is also scientific uncertainty about the effects of low-level radiation because of the discoveries being made in Harwell, Dublin and Harvard about genomic instability. The key to how people perceive risks is the degree of control they exert over them. People are not in control of the risks they encounter from radiation. Hence they dislike additions of artificial radioactivity from bomb tests, Chernobyl and Sellafield. This is a sensible response that should be dealt with honestly.

Prevalence and degree of expression of the carbapenemase gene (cfiA) among clinical isolates of Bacteroides fragilis in Nottingham, UK

The carbapenemase gene (cfiA) was detected in 12 (6.9%) out of 175 clinical isolates of Bacteroides fragilis from Nottingham, three times the frequency reported from France. Only one gene copy was present in all cases. Eleven (6.3%) of the cfiA-positive isolates were susceptible to imipenem or meropenem (MIC < 8 mg/L); strains of this type have the potential to convert to high-level resistance. One isolate (0.6%) displayed resistance to both carbapenem antibiotics and was associated with specific carbapenemase activity six times that of the sensitive isolates.

Higher plant tyrosine-specific protein phosphatases (PTPs) contain novel amino-terminal domains: expression during embryogenesis

Sequences encoding proteins with homology to protein tyrosine phosphatases have been identified in Arabidopsis, soybean and pea. Each contains a predicted catalytic domain containing sequence motifs characteristic of tyrosine-specific protein phosphatases (PTPs) which play an important role in signal transduction in other eukaryotes and are distinct from dual-specificity, cdc25 or low-molecular-weight protein tyrosine phosphatases. Their identity as PTPs was confirmed by characterising the soybean PTP expressed as a recombinant His-tagged fusion protein. The enzyme had phosphatase activity towards p-nitrophenolphosphate (pNPP) and phosphotyrosine, but did not hydrolyse phosphoserine or phosphothreonine at a measureable rate. Phosphotyrosine containing peptides also served as substrates, with Km values in the micromolar range. Activity was abolished by inhibitors specific for tyrosine phosphatases (vanadate, dephostatin) but was unaffected by inhibitors of serine/threonine protein phosphatases (fluoride, cantharidin, metal-chelating agents). Gel filtration chromatography showed that the recombinant enzyme was a monomer. The Arabidopsis PTP sequence was isolated both as a genomic clone and as a partial EST, whereas the pea and soybean sequences were isolated as cDNAs. Southern analysis suggested a single gene in Arabidopsis and a small gene family in pea and soybean. In pea, PTP transcripts were present in embryos, and decreased in level with development; transcripts were also detectable in other tissues. The plant PTPs all contain a similar N-terminal domain which shows no similarity to any known protein sequence. This domain may be involved in PTP functions unique to plants.

Quantitative analysis of rapid pointing movements in Cree subjects exposed to mercury and in subjects with neurological deficits

To quantify rapid and precise proximo-distal movements, we have developed a simple system (eurythmokinesimeter or EKM) which requires the subject to touch alternately the center of proximal and distal targets with a stylus. Ninety-six participants, including 30 controls subjects, 36 Cree subjects exposed to mercury, 21 subjects with Parkinson disease, 6 with presumed cerebellar deficit, and 3 with essential tremor, participated in the study. A total of nine measures, including precision, imprecision, contact duration, unsureness, tremor, transit time, irregularity, speed, and Fitts' constant, were calculated. Test-retest reliability was above 0.8 for most measures and above 0.9 for many measures. Correlations between measures and number of outliers with respect to the control group distribution for each measure were used to reduce the set of measures to five (i.e., precision, imprecision, tremor, Fitts' constant, and irregularity). An ANOVA on the three largest groups generated significant results for tremor, Fitts' constant, and irregularity between the Cree and the control subjects and on Fitts' constant and irregularity between the subjects with Parkinson's disease and the control subjects. Three subgroups of the same mean age composed of six subjects each were selected. One was composed of Cree subjects with the highest level of mercury exposure, another with Cree subjects having a low level of mercury exposure, and a third with control subjects. An ANOVA on these three groups revealed a significant difference between both groups of Cree subjects and the control group for Fitts' constant and irregularity. These preliminary results suggest that the EKM system is able to discriminate the performance of different groups of subjects.

Parkinsonian tremor and simplification in network dynamics

We explore the behavior of richly connected inhibitory neural networks under parameter changes that correspond to weakening of synaptic efficacies between network units, and show that transitions from irregular to periodic dynamics are common in such systems. The weakening of these connections leads to a reduction in the number of units that effectively drive the dynamics and thus to simpler behavior. We hypothesize that the multiple interconnecting loops of the brain's motor circuitry, which involve many inhibitory connections, exhibit such transitions. Normal physiological tremor is irregular while other forms of tremor show more regular oscillations. Tremor in Parkinson's disease, for example, stems from weakened synaptic efficacies of dopaminergic neurons in the nigro-striatal pathway, as in our general model. The multiplicity of structures involved in the production of symptoms in Parkinson's disease and the reversibility of symptoms by pharmacological and surgical manipulation of connection parameters suggest that such a neural network model is appropriate. Furthermore, fixed points that can occur in the network models are suggestive of akinesia in Parkinson's disease. This model is consistent with the view that normal physiological systems can be regulated by robust and richly connected feedback networks with complex dynamics, and that loss of complexity in the feedback structure due to disease leads to more orderly behavior.

Analysis of rapid alternating movements in Cree subjects exposed to methylmercury and in subjects with neurological deficits

To quantify rapid alternating movements (RAMs) we used a simple prototype developed in our laboratory that requires the subject to rotate two hand-held foam spheres connected to optical encoders via flexible rods. Ninety-six participants, including 30 control subjects, 36 Cree subjects exposed to methylmercury, 21 subjects with Parkinson's disease, 6 subjects with cerebellar deficits, and 3 subjects with essential tremor, were involved in the study (though data for 5 were later removed). Twelve characteristics were developed and calculated from the raw data. Conditions examined included two hands at natural cadence (NC2), right and left hands separately at fast cadence (FCl), and both hands at fast cadence (FC2). Two ratios (FC2/NC2) and (FC2/FC1) combining these conditions were also examined. Test-retest reliability was >0.80 for most characteristics but was <0.70 for some characteristics, especially in the conditions executed at normal cadence. Correlations between characteristics and numbers of outliers with respect to the control group distribution were used to reduce the set of characteristics from 12 to 7 (i.e., duration, range, maximum slope, similarity in shape, smoothness, sharpness, and coherence). ANOVAs on the three largest groups generated significant results for most characteristics in the three conditions and the two ratios for Cree subjects and subjects with Parkinson's disease. ANOVAs on 3 age-matched groups (n=6) suggest that methylmercury affects the performance of the Cree subjects with the higher exposure, especially in terms of smoothness, sharpness, and coherence. These preliminary results suggest that this test is sufficiently specific and sensitive to characterize the performance of different groups of subjects. Ratios tend to improve discrimination for Cree subjects in a few characteristics but not for patients with Parkinson's disease.

The biosynthetic relationship between littorine and hyoscyamine in transformed roots of Datura stramonium

The metabolic relationship between littorine and hyoscyamine has been monitored in transformed roots of Datura stramonium. Quantification by GC of unlabelled littorine and by GCMS of ¹³C-labelled littorine demonstrated that exogenously added littorine (0.1 mM) was significantly metabolised (35%) to hyoscyamine. In contrast, exogenously added hyoscyamine was not metabolised to littorine, indicating that this conversion is irreversible. The conversion of littorine to hyoscyamine was suppressed by P-450 oxidase inhibitors (particularly clotrimazole), implicating the involvement, at least in part of a cytochrome P-450 activity operating hyoscyamine biosynthesis.

Serotype distribution and prevalence of resistance to benzylpenicillin in three representative populations of Streptococcus pneumoniae isolates from the coast of Kenya

As surveillance data from sub-Saharan Africa are few, three representative populations of Streptococcus pneumoniae isolates were examined in Kenya for serotype distribution and Etest minimum inhibitory concentrations (MICs) of benzylpenicillin: (1) 75 lung aspirate or blood culture isolates from 301 consecutive adult patients with pneumonia, (2) 112 invasive isolates from continuous pediatric inpatient surveillance over 4 years, and (3) 97 nasopharyngeal isolates from systematically selected sick children. The proportions with benzylpenicillin MICs of > or = 0.1 microgram/mL were 0.27, 0.29, and 0.47, respectively. Vaccine-related serotypes accounted for 96% of invasive isolates from children and 90% of those from human immunodeficiency virus (HIV)-seropositive adults. Serotype 1 accounted for 44% of pneumococci from HIV-seronegative patients but only 5% of those from HIV-seropositive patients (P = .0002). Of serotype 1 isolates, 98% were susceptible to benzylpenicillin, but serogroups 13, 14, 19, and 23 were strongly associated with an MIC of > or = 0.1 microgram/mL.

Tremor in Cree subjects exposed to methylmercury: a preliminary study

Rest, postural, and kinetic tremors were recorded in Cree subjects (n = 36) exposed to low levels of methylmercury (MeHg) and control subjects (n = 30) using lasers designed to measure displacement. Displacement and derived velocity and acceleration time series were analyzed using quantitative characteristics in time and frequency domains. We found: 1) relatively low agreement between our results and those of a clinical examination done at the time of testing (r = 0.31 for postural tremor); 2) best discrimination with velocity of static (postural with visual feedback) and kinetic tremors for which significant differences between the two groups are found in many of the characteristics examined; 3) myoclonic-like finger microdisplacements in tremor of Cree subjects; 4) significant changes in static tremor of Cree subjects following a kinetic task; 5) significant differences among three age-matched subgroups of six subjects each (Cree with higher and lower MeHg level, and a control group) in characteristics that reflect difficulty with tracking, myoclonic-like microdisplacements and change in frequency composition of tremor after the tracking task. The subtle differences detected in this preliminary study suggest that further work is warranted to determine whether they can be unambiguously associated with exposure to MeHg.

Safety of mefloquine and other antimalarial agents in the first trimester of pregnancy

BACKGROUND

Safe and effective antimalarials are required to protect pregnant women from the harmful effects of malaria.

METHODS

Data were collected from two separate prospective cohorts to ascertain the safety of chloroquine-proguanil, sulfadoxine-pyrimethamine (SP), and mefloquine taken in the first trimester of pregnancy.

RESULTS

In a traveler cohort of 236 pregnant women, spontaneous abortions were reported in 7.6% of 99 women taking chloroquine-proquanil, 0% of 19 taking sulfadoxine-pyrimethamine, and 9.1% of 118 women taking mefloquine. Anomalies were identified in 1.7%, 0% and 0% of the same cohort, respectively. Differences in rates of adverse outcomes between the three groups were not statistically significant. In a pharmaceutical database of 331 and 153 women exposed to mefloquine and SP, respectively, the overall rate of abnormal outcomes (spontaneous abortions plus fetal anomalies) was not significantly different (p=.29). Spontaneous abortions were significantly higher with mefloquine than SP (9.1% and 2.6%, respectively; p=.01), but the higher rate was comparable to background rates (7%-11%). Fetal anomalies in the mefloquine group (4.8%) were lower than the SP group (7.8%), but this was statistically not significant (p=.19), and was comparable with the background rate of 4.6% (p=.84). However, mefloquine exposure resulted in a significantly higher rate of therapeutically induced abortions, undertaken for perceived risk to the fetus, compared with SP (p<.0001).

CONCLUSION

From the clinical data available, there is no indication that the risk of taking mefloquine in the first trimester of pregnancy is greater than that from any of the other antimalarials studied and the risk is considerably lower than that associated with falciparum malaria.