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The current assays to confirm herbicide resistance can be time- and labor-intensive (dose–response) or require a skill set/technical equipment (genetic sequencing). Stakeholders could benefit from a rapid assay to confirm herbicide-resistant weeds to ensure sustainable crop production. Because protoporphyrinogen oxidase (PPO)-inhibiting herbicides rapidly interfere with chlorophyll production/integrity; we propose a new, rapid assay utilizing spectral reflectance to confirm resistance. Leaf disks were excised from two PPO-inhibiting herbicide-resistant (target-site [TSR] and non–target site [NTSR]) and herbicide-susceptible redroot pigweed (Amaranthus retroflexus L.) populations and placed into a 24-well plate containing different concentrations (0 to 10 mM) of fomesafen for 48 h. A multispectral sensor captured images from the red (668 nm), green (560 nm), blue (475 nm), and red edge (717 nm) wavebands after a 48-h incubation period. The green leaf index (GLI) was utilized to determine spectral reflectance ratios of the treated leaf disks. Clear differences of spectral reflectance were observed in the red edge waveband for all populations treated with the 10 mM concentration in the dose–response assays. Differences of spectral reflectance were observed for the NTSR population compared with the TSR and susceptible populations treated with the 10 mM concentration in the green waveband and the GLI in the dose–response assay. Leaf disks from the aforementioned A. retroflexus populations and two additional susceptible populations were subjected to a similar assay with the discriminating concentration (10 mM). Spectral reflectance was different between the PPO-inhibiting herbicide-resistant and herbicide-susceptible populations in the red, blue, and green wavebands. Spectral reflectance was not distinctive between the populations in the red edge waveband and the GLI. The results provide a basis for rapidly (∼48 h) detecting PPO-inhibiting herbicide-resistant A. retroflexus via spectral reflectance. Discrimination between TSR and NTSR populations was possible only in the dose–response assay, but the assay still has utility in distinguishing herbicide-resistant plants from herbicide-susceptible plants.
Complaints of control failures with acetolactate synthase (ALS)- and protoporphyrinogen oxidase (PPO)-inhibiting herbicides on redroot pigweed (Amaranthus retroflexus L.) were reported in conventional soybean [Glycine max (L.) Merr.] fields in North Carolina. Greenhouse dose–response assays confirmed that the Camden County and Pasquotank County populations were less sensitive to ALS- and PPO-inhibiting herbicides compared with susceptible A. retroflexus populations, suggesting the evolution of resistance to these herbicides. Sanger sequencing of target genes determined the Camden County population carried a Trp-574-Leu mutation in the ALS gene and an Arg-98-Gly mutation in the PPX2 gene, while the Pasquotank County population carried a His-197-Pro mutation in the ALS gene (first documentation of the mutation in the Amaranthus genus), but no mutation was detected in the PPX2 gene. Single-nucleotide polymorphism (SNP) genotyping assays were developed to enable efficient screening of future control failures in order to limit the spread of these herbicide-resistant populations. In addition, preliminary testing of these assays revealed the three mutations were ubiquitous in the respective populations. These two populations represent the first confirmed cases of PPO-inhibiting herbicide-resistant A. retroflexus in the United States, as well as the first confirmed cases of this particular herbicide-resistance profile in A. retroflexus inhabiting North America. While no mutation was found in the PPX2 gene of the Pasquotank County population, we suggest that this population has evolved resistance to PPO-inhibiting herbicides, but the mechanism of resistance is to be determined.
Glufosinate is an effective postemergence herbicide, and overreliance on this herbicide for weed control is likely to increase and select for glufosinate-resistant weeds. Common assays to confirm herbicide resistance are dose–response and molecular sequencing techniques; both can require significant time, labor, unique technical equipment, and a specialized skillset to perform. As an alternative, we propose an image-based approach that uses a relatively inexpensive multispectral sensor designed for unmanned aerial vehicles to measure and quantify surface reflectance from glufosinate-treated leaf disks. Leaf disks were excised from a glufosinate-resistant and glufosinate-susceptible corn (Zea mays L.), cotton (Gossypium hirsutum L.), and soybean [Glycine max (L.) Merr.] varieties and placed into a 24-well plate containing eight different concentrations (0 to 10 mM) of glufosinate for 48 h. Multispectral images were collected after the 48-h incubation period across five discrete wave bands: blue (475 to 507 nm), green (560 to 587 nm), red (668to 682 nm), red edge (717 to 729 nm), and near infrared (842 to 899 nm). The green leaf index (GLI; a metric to measure chlorophyll content) was utilized to determine relationships between measured reflectance from the tested wave bands from the treated leaf disks and the glufosinate concentration. Clear differences of spectral reflectance were observed between the corn, cotton, and soybean leaf disks of the glufosinate-resistant and glufosinate-susceptible varieties at the 10 mM concentration for select wave bands and GLI. Leaf disks from two additional glufosinate-resistant and glufosinate-susceptible varieties of each crop were subjected to a similar assay with two concentrations: 0 and 10 mM. No differences of spectral reflectance were observed from the corn and soybean varieties in all wave bands and the GLI. The leaf disks of the glufosinate-resistant and glufosinate-susceptible cotton varieties were spectrally distinct in the green, blue, and red-edge wave bands. The results provide a basis for rapidly detecting glufosinate-resistant plants via spectral reflectance. Future research will need to determine the glufosinate concentrations, useful wave bands, and susceptible/resistant thresholds for weeds that evolve resistance.
Sugar-sweetened beverage (SSB) consumption has declined steadily. This study uses the latest national data to examine trends in SSB consumption among children and adults by race and/or ethnicity and to document whether long-standing disparities in intake remain.
Design:
Trend analyses of demographic and dietary data measured by 24-h dietary recall from the National Health and Nutrition Examination Survey (NHANES).
Setting:
Data from the 2003–2004 through 2017–2018 NHANES survey cycles were analysed in 2020.
Participants:
The study sample included 21 156 children aged 2–19 years and 32 631 adults aged 20+ years.
Results:
From 2003–2004 to 2017–2018, the prevalence of drinking any amount of SSB on a given day declined significantly among all race and/or ethnicity groups for children (non-Hispanic (NH) White: 81·6 % to 72·7 %; NH Black: 83·2 % to 74·8 %, Hispanic: 86·9 % to 77·2 %) and most race and/or ethnicity groups for adults (NH White: 72·3 % to 65·3 %; Hispanic: 84·6 % to 77·8 %). Consumption declined at a higher rate among NH Black and Hispanic children aged 12–19 years compared with their NH White peers; among NH Black children aged 6–11 years, the rate of decline was lower. Despite significant declines in per capita SSB energy consumption from soda and fruit drinks, consumption of sweetened coffee/tea beverages increased among older children and nearly all adults and consumption of sweetened milk beverages increased among NH White and Hispanic children.
Conclusions:
SSB consumption has declined steadily for children and adults of all race and/or ethnicity groups, but disparities persist, and overall intake remains high.
To examine the prevalence and nutrient composition of menu offerings targeted to customers with dietary restrictions at US fast casual and full-service chain restaurants.
Design:
We used 2018 data from MenuStat, a database of nutrient information for menu items at large US chain restaurants. Five alternative diets were examined: gluten-free, low-calorie, low-carbohydrate, low-fat and vegetarian. Diet offerings were identified by searching MenuStat item descriptions and reviewing online menus. For each diet, we reported counts and proportions. We used bootstrapped multilevel models to examine differences in predicted mean kilojoules, saturated fat, Na and sugars between diet and non-diet menu items.
Setting:
Forty-five US fast casual and full-service chain restaurants in 2018 (including 6419 items in initial analytic sample across small plates, salads and main dishes).
Participants:
None.
Results:
The most prevalent diets were gluten-free (n 631, 9·8 % of menu items), low-calorie (n 306, 4·8 %) and vegetarian (n 230, 3·6 %). Compared with non-diet counterparts, low-calorie main dishes had significantly lower levels of all nutrients examined and vegetarian main dishes had significantly lower levels of all nutrients except saturated fat. Gluten-free small plates had significantly fewer kilojoules, grams of saturated fat and milligrams of Na compared with non-diet small plates.
Conclusions:
A small proportion of fast casual and full-service restaurant menus are targeted towards customers with dietary restrictions. Compared with non-diet items, those classified as gluten-free, low-calorie or vegetarian generally have healthier nutrient profiles, but overall nutrient values are still too high for most menu items, regardless of dietary label.
Gravitational waves from coalescing neutron stars encode information about nuclear matter at extreme densities, inaccessible by laboratory experiments. The late inspiral is influenced by the presence of tides, which depend on the neutron star equation of state. Neutron star mergers are expected to often produce rapidly rotating remnant neutron stars that emit gravitational waves. These will provide clues to the extremely hot post-merger environment. This signature of nuclear matter in gravitational waves contains most information in the 2–4 kHz frequency band, which is outside of the most sensitive band of current detectors. We present the design concept and science case for a Neutron Star Extreme Matter Observatory (NEMO): a gravitational-wave interferometer optimised to study nuclear physics with merging neutron stars. The concept uses high-circulating laser power, quantum squeezing, and a detector topology specifically designed to achieve the high-frequency sensitivity necessary to probe nuclear matter using gravitational waves. Above 1 kHz, the proposed strain sensitivity is comparable to full third-generation detectors at a fraction of the cost. Such sensitivity changes expected event rates for detection of post-merger remnants from approximately one per few decades with two A+ detectors to a few per year and potentially allow for the first gravitational-wave observations of supernovae, isolated neutron stars, and other exotica.
To compare the nutritional quality of children’s combination meals offered at large US chain restaurants characterised by three versions – default (advertised), minimum (lower-energy) and maximum (higher-energy).
Design:
We identified default children’s meals (n 92) from online restaurant menus, then constructed minimum and maximum versions using realistic additions, substitutions and/or portion size changes for existing menu items. Nutrition data were obtained from the MenuStat database. Bootstrapped linear models assessed nutrition differences between meal versions and the extent to which meal components (main dish, side dish, beverage) drove differences across versions. For each version, we examined the proportion of meals meeting the Guidelines for Responsible Food Marketing to Children.
Setting:
Twenty-six fast-food and fast-casual restaurants, in 2017.
Participants:
None.
Results:
Nutrient values differed significantly across meal versions for energy content (default 2443 kJ (584 kcal), minimum 1674 kJ (400 kcal), maximum 3314 kJ (792 kcal)), total fat (23, 17, 33 g), saturated fat (8, 6, 11 g), Na (1046, 915, 1287 mg) and sugar (35, 14, 51 g). The substitution of lower-energy beverages resulted in the greatest reduction in energy content (default to minimum, −418 kJ (−100 kcal)) and sugar (−20 g); choosing lower-energy side dishes resulted in the greatest reduction in total fat (default to minimum, −4 g), saturated fat (−1·1 g) and Na (−69 mg). Only 3 % of meals met guidelines for all nutrients.
Conclusions:
Realistic modifications to children’s combination meals using existing menu options can significantly alter a meal’s nutrient composition. Promoting lower-energy items as the default option, especially for beverages and side dishes, has a potential to reduce fat, saturated fat and/or sugar in children’s meals.
There is some evidence that anti-inflammatory treatment may have beneficial effects in schizophrenia and major depression. Statins are cholesterol-lowering agents but have been found to be anti-inflammatory and also decrease C-reactive protein (CRP). Ondansetron is a serotonin (5-HT3) receptor antagonist widely used to prevent nausea and vomiting in patients receiving chemotherapy for cancer. Small studies have suggested that adjunctive Ondansetron is efficacious against schizophrenia symptoms. We carried out a feasibility study in schizophrenia patients (within 5 years of first diagnosis) to explore the adjunctive use of simvastatin and ondansetron on positive, negative and general psychopathology.
Methods
This was a 12 week rater blind placebo controlled study. All to gather 36 patients with DSM-IV diagnosis of schizophrenia were recruited, 12 in each arm. Patients were assessed at baseline and at 12 weeks using PANSS, CGI, GAF and AIMS.
Results
Both simvastatin and ondansetron provide some evidence of a reduction in symptoms compared to treatment as usual (TAU) on PANSS total score, although, this was not statistically significant. In the secondary analyses, no significant differences were seen on CGI, GAF and AIMS.
Conclusions
Anti-inflammatory treatments have shown to have some beneficial effects in schizophrenia. Both simvastatin and ondansetron provide some evidence of a reduction in symptoms compared to treatment as usual. This study has led to a larger SMRI-funded, double blind, randomized control trial.
Immune mechanisms have been implicated in the pathogenesis of schizophrenia. This has lead to clinical trials of re-purposing drugs with off-target anti-inflammatory actions. They include the antibiotic minocycline and simvastatin (HMP-Co reductase inhibitor), which decrease microglial activation, and ondansetron a 5-HT3-receptor antagonist that has limited effects on cytokine production. This presentation will address their efficacy and mechanism of action.
Aims
1) Update on trials with minocycline including our own positive finding on negative symptoms (PMID: 16959472)
2) Present new results with ondansetron and simvastatin summarised below.
Methods
Ondansetron (8mg) and simvastatin (40mg) vs placebos in 2x2 design (PMID: 23782463). Patients aged 18-65, stable treatment, DSM IV schizophrenia-related diagnosis. PANSS and cognition at 0,3,6 months.
Results
The four cells of the 2x2 design contained 302 patients. The interaction between ondansetron and simvastatin was significant at p=.006 reflecting the lower scores in the 3 active treatment groups than in the P+P group. Ondansetron improved verbal (p=.007) and visual list learning (p=.02) with no other treatment effects on cognition.
Conclusions
Minocycline appears to benefit negative symptoms in early psychosis with a minor effect on cognition. Simvastatin had limited effects in our patients with established schizophrenia but its anti-inflammatory effects could be worth investigating in early psychosis. Ondansetron has a significant effect on new learning, which might be expected from its 5-HT3 antagonist properties. This may underlie a benefit on negative symptoms reported by others and us.
To understand price incentives to upsize combination meals at fast-food restaurants by comparing the calories (i.e. kilocalories; 1 kcal = 4·184 kJ) per dollar of default combination meals (as advertised on the menu) with a higher-calorie version (created using realistic consumer additions and portion-size changes).
Design:
Combination meals (lunch/dinner: n 258, breakfast: n 68, children’s: n 34) and their prices were identified from online menus; corresponding nutrition information for each menu item was obtained from a restaurant nutrition database (MenuStat). Linear models were used to examine the difference in total calories per dollar between default and higher-calorie combination meals, overall and by restaurant.
Setting:
Ten large fast-food chain restaurants located in the fifteen most populous US cities in 2017–2018.
Participants:
None.
Results:
There were significantly more calories per dollar in higher-calorie v. default combination meals for lunch/dinner (default: 577 kJ (138 kcal)/dollar, higher-calorie: 707 kJ (169 kcal)/dollar, difference: 130 kJ (31 kcal)/dollar, P < 0·001) and breakfast (default: 536 kJ (128 kcal)/dollar, higher-calorie: 607 kJ (145 kcal)/dollar, difference: 71 kJ (17 kcal)/dollar, P = 0·009). Results for children’s meals were in the same direction but were not statistically significant (default: 536 kJ (128 kcal)/dollar, higher-calorie: 741 kJ (177 kcal)/dollar, difference: 205 kJ (49 kcal)/dollar, P = 0·053). Across restaurants, the percentage change in calories per dollar for higher-calorie v. default combination meals ranged from 0·1 % (Dunkin’ Donuts) to 55·0 % (Subway).
Conclusions:
Higher-calorie combination meals in fast-food restaurants offer significantly more calories per dollar compared with default combination meals, suggesting there is a strong financial incentive for consumers to ‘upsize’ their orders. Future research should test price incentives for lower-calorie options to promote healthier restaurant choices.
The smr and qacA/B genes in Staphylococcus aureus confer tolerance to antiseptics and are associated with nosocomial acquisition of infection and underlying medical conditions. Such antiseptic tolerance (AT) genes have also been reported in coagulase-negative staphylococci (CoNS) and enterococci, however, few data are available regarding their prevalence. We sought to describe the frequency of AT genes among bloodstream isolates of S. aureus, CoNS and enterococci at Texas Children’s Hospital (TCH).
Methods:
Banked CoNS, S. aureus and enterococci isolated from blood cultures collected bewteen October 1, 2016, and October 1, 2017, were obtained from the TCH clinical microbiology laboratory. All isolates underwent polymerase chain reaction (PCR) assay for the qacA/B and smr genes. Medical records were reviewed for all cases.
Results:
In total, 103 CoNS, 19 Enterococcus spp, and 119 S. aureus isolates were included in the study, and 80.6% of the CoNS possessed at least 1 AT gene compared to 37% of S. aureus and 43.8% of E. faecalis isolates (P < .001). Among CoNS bloodstream isolates, the presence of either AT gene was strongly associated with nosocomial infection (P < .001). The AT genes in S. aureus were associated with nosocomial infection (P = .025) as well as the diagnosis of central-line–associated bloodstream infection (CLABSI; P = .04) and recent hospitalizations (P < .001). We found no correlation with genotypic AT in E. faecalis and any clinical variable we examined.
Conclusions:
Antiseptic tolerance is common among bloodstream staphylococci and E. faecalis isolates at TCH. Among CoNS, the presence of AT genes is strongly correlated with nosocomial acquisition of infection, consistent with previous studies in S. aureus. These data suggest that the healthcare environment contributes to AT among staphylococci.
Multiple studies have demonstrated that daily chlorhexidine gluconate (CHG) bathing is associated with a significant reduction in infections caused by gram-positive pathogens. However, there are limited data on the effectiveness of daily CHG bathing on gram-negative infections. The aim of this study was to determine whether daily CHG bathing is effective in reducing the rate of gram-negative infections in adult intensive care unit (ICU) patients.
Design:
We searched MEDLINE and 3 other databases for original studies comparing daily bathing with and without CHG. Two investigators extracted data independently on baseline characteristics, study design, form and concentration of CHG, incidence, and outcomes related to gram-negative infections. Data were combined using a random-effects model and pooled relative risk ratios (RRs), and 95% confidence intervals (CIs) were derived.
Results:
In total, 15 studies (n = 34,895 patients) met inclusion criteria. Daily CHG bathing was not significantly associated with a lower risk of gram-negative infections compared with controls (RR, 0.89; 95% CI, 0.73–1.08; P = .24). Subgroup analysis demonstrated that daily CHG bathing was not effective for reducing the risk of gram-negative infections caused by Acinetobacter, Escherichia coli, Klebsiella, Enterobacter, or Pseudomonas spp.
Conclusions:
The use of daily CHG bathing was not associated with a lower risk of gram-negative infections. Further, better designed trials with adequate power and with gram-negative infections as the primary end point are needed.
Iowaite has been re-examined using new, well crystallized material from the Palabora open pit mine, Transvaal. Microprobe, carbon analyser and thermal analyses, powder and single-crystal X-ray diffraction, infrared, UV-visible and mass spectroscopic and optical studies were made. The ideal formula is (OH)16Cl2·4H2O. It is trigonal, R3̄m, a = 3.1183(9), c = 24.113(8) Å, V = 203.1(2) Å3, Z = 3/8; Dobs 2.09 g/cm3.; Dcalc 2.04 g/cm3; hardness (Mohs)=2 1/2. The interlayer Cl− ions are displaced from the threefold axis. It is uniaxial negative, with ω = 1.561 ± 0.002, ε = 1.543 ± 0.002; coloured crystals are intensely pleochroic, due to intervalence charge transfer between the Fe3+ and Fe2+ substituting for Mg2+, with O pale yellow, E deep blue-green.
To understand increasing rates of hepatitis C virus (HCV) infection in Tennessee, we conducted testing, risk factor analysis and a nested case–control study among persons who use drugs. During June–October 2016, HCV testing with risk factor assessment was conducted in sexually transmitted disease clinics, family planning clinics and an addiction treatment facility in eastern Tennessee; data were analysed by using multivariable logistic regression. A nested case–control study was conducted to assess drug-using risks and behaviours among persons who reported intranasal or injection drug use (IDU). Of 4753 persons tested, 397 (8.4%) were HCV-antibody positive. HCV infection was significantly associated with a history of both intranasal and IDU (adjusted odds ratio (aOR) 35.4, 95% confidence interval (CI) 24.1–51.9), IDU alone (aOR 52.7, CI 25.3–109.9), intranasal drug use alone (aOR 2.6, CI 1.8–3.9) and incarceration (aOR 2.7, CI 2.0–3.8). By 4 October 2016, 574 persons with a reported history of drug use; 63 (11%) were interviewed further. Of 31 persons who used both intranasal and injection drugs, 26 (84%) reported previous intranasal drug use, occurring 1–18 years (median 5.5 years) before their first IDU. Our findings provide evidence that reported IDU, intranasal drug use and incarceration are independent indicators of risk for past or present HCV infection in the study population.
The effects of shape and thickness of a tin surface layer and of the energy of a 170 ps neodymium:yttrium-aluminum-garnet laser pulse on the conversion efficiency (CE) into extreme ultraviolet emission in the 13.5 nm region is investigated. Whereas a CE of up to 1.16% into the 2% reflection band of multilayer Mo/Si optics was measured for a bulk Sn target at a laser energy of 25 mJ, significant CE enhancement up to 1.49% is demonstrated for a 200-nm-thick Sn layer on a microstructured porous alumina substrate.
Research is sparse which examines pathways to suicide, and resilience to suicide, in people who are particularly vulnerable to suicide, for example, prison inmates. The purpose of this study was to examine the ways in which perceptions of self-esteem and coping ability interacted with defeat and entrapment to both amplify suicidal thoughts and feelings, and to act as a buffer against suicidal thoughts and feelings.
Methods
Participants were 65 male prisoners at high risk of suicide. A cross-sectional questionnaire design was used. Questionnaire measures of depression, defeat, entrapment, self-esteem, coping ability and suicidal probability were administered.
Results
For the hopelessness component of the suicide probability measure, high levels of coping ability together with low levels of defeat resulted in the lowest levels of suicidality indicative of a resilience factor. In contrast, low levels of coping skills together with high levels of entrapment were a high risk factor for this hopelessness component of suicide. This pattern of results pertained when controlling for depression levels.
Conclusions
This is the first study to examine interactions between defeat, entrapment and appraisals of self-esteem and coping ability. Therapeutic interventions would benefit from boosting perceptions and appraisals of coping ability, in particular, in people who are at high risk for suicide.
Prisoners have an exceptional risk of suicide. Cognitive–behavioural therapy for suicidal behaviour has been shown to offer considerable potential, but has yet to be formally evaluated within prisons. This study investigated the feasibility of delivering and evaluating a novel, manualized cognitive–behavioural suicide prevention (CBSP) therapy for suicidal male prisoners.
Method.
A pilot randomized controlled trial of CBSP in addition to treatment as usual (CBSP; n = 31) compared with treatment as usual (TAU; n = 31) alone was conducted in a male prison in England. The primary outcome was self-injurious behaviour occurring within the past 6 months. Secondary outcomes were dimensions of suicidal ideation, psychiatric symptomatology, personality dysfunction and psychological determinants of suicide, including depression and hopelessness. The trial was prospectively registered (number ISRCTN59909209).
Results.
Relative to TAU, participants receiving CBSP therapy achieved a significantly greater reduction in suicidal behaviours with a moderate treatment effect [Cohen's d = −0.72, 95% confidence interval −1.71 to 0.09; baseline mean TAU: 1.39 (s.d. = 3.28) v. CBSP: 1.06 (s.d. = 2.10), 6 months mean TAU: 1.48 (s.d. = 3.23) v. CBSP: 0.58 (s.d. = 1.52)]. Significant improvements were achieved on measures of psychiatric symptomatology and personality dysfunction. Improvements on psychological determinants of suicide were non-significant. More than half of the participants in the CBSP group achieved a clinically significant recovery by the end of therapy, compared with a quarter of the TAU group.
Conclusions.
The delivery and evaluation of CBSP therapy within a prison is feasible. CBSP therapy offers significant promise in the prevention of prison suicide and an adequately powered randomized controlled trial is warranted.
We describe a laboratory plasma physics experiment at Los Alamos National Laboratory that uses two merging supersonic plasma jets formed and launched by pulsed-power-driven railguns. The jets can be formed using any atomic species or mixture available in a compressed-gas bottle and have the following nominal initial parameters at the railgun nozzle exit: ne ≈ ni ~ 1016 cm−3, Te ≈ Ti ≈ 1.4 eV, Vjet ≈ 30–100 km/s, mean charge $\bar{Z}$ ≈ 1, sonic Mach number Ms ≡ Vjet/Cs > 10, jet diameter = 5 cm, and jet length ≈20 cm. Experiments to date have focused on the study of merging-jet dynamics and the shocks that form as a result of the interaction, in both collisional and collisionless regimes with respect to the inter-jet classical ion mean free path, and with and without an applied magnetic field. However, many other studies are also possible, as discussed in this paper.
We describe nine females with Rett Syndrome (RS), aged 14 to 26 years. All had had developmental delay before the end of their first year and had subsequently regressed to profound dementia with apraxia, ataxia, irregular respirations and often also seizures.
Methods:
The Revised Gesell developmental assessment and Alpern-Boll Developmental Profile were used in modified form. Volumetric measurements of basal ganglia using MRI were compared with the findings in nine age-matched volunteer females. Positron emission scans with [18F]-6-fluorodopa and [11C]-raclopride were performed under light anesthesia with intravenous Propofol, and the findings were compared with those in healthy control girls. Bidirectional sequencing of the coding regions of the MECP2 gene was investigated in blood samples for mutational analyses.
Results:
The RS females functioned at a mental age level ranging from about 4 to 15 months. The scores correlated with height, weight and head circumference. Magnetic resonance scans of basal ganglia showed a significant reduction in the size of the caudate heads and thalami in the Rett cases. Positron emission scans demonstrated that the mean uptake of fluorodopa in RS was reduced by 13.1% in caudate and by 12.5% in putamen as compared to the controls, while dopamine D2 receptor binding was increased significantly by 9.7% in caudate and 9.6% in putamen. Mutations in the coding regions of the MECP2 gene were present in all nine patients. No significant correlation between type and location of mutation and volumetric changes or isotope uptake was demonstrable.
Conclusion:
Our findings suggest a mild presynaptic deficit of nigrostriatal activity in Rett syndrome.