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OBJECTIVE: Chronic low back pain (cLBP) affects nociceptive responses in the cerebellum, which leads to increased pain perception and sensorimotor control dysfunction. This study aimed to investigate altered functional connectivity in the anterior and posterior lobes of the cerebellum during cLBP. DESIGN: Twenty patients with cLBP and 18 healthy participants underwent 3.0 T resting-state functional magnetic resonance imaging. The bilateral lobule V of the anterior cerebellum and Crus I of the posterior cerebellum were selected as the region of interest for identifying the corresponding networks. RESULTS: The left lobule V had a greater intrinsic connectivity with the left insular cortex, left orbitofrontal cortex, and bilateral medial prefrontal cortex in patients with cLBP. In contrast, the right lobule V and bilateral Crus I had a significantly decreased connectivity with the contralateral multimodal cerebral networks, including the default mode network, salience network, and emotional network. CONCLUSION: The cerebellum had mechanistic implications in pain-related changes, which are involved in motor control, cognition, and emotion processing. These findings provide a novel perspective on the role of functional subregions in cLBP, which add to the growing body of evidence that the cerebellum can be a potential target for noninvasive brain stimulation for chronic pain treatment.
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The organic matter molecular mechanism by which combined hydrothermal carbonization (co-HTC) of municipal sludge (MS) and agricultural wastes (rice husk, spent mushroom substrate, and wheat straw) reduces the inhibitory effects of aqueous phase (AP) products on pak choi (Brassica campestris L.) growth compared to HTC of MS alone is not clear. Fourier-transform ion cyclotron resonance mass spectrometry was used to characterize the differences in organic matter at the molecular level between AP from MS HTC alone (AP-MS) and AP from co-HTC of MS and agricultural waste (co-Aps). The results showed that N-bearing molecules of AP-MS and co-Aps account for 70.6 % and 54.2 %-64.1 % of all molecules, respectively. Lignins were present in the highest proportion (56.3 %-78.5 %) in all APs, followed by proteins and lipids. The dry weight of co-APs hydroponically grown pak choi was 31.6 %-47.6 % higher than that of the AP-MS. Molecules that were poorly saturated and with low aromaticity were preferentially consumed during hydroponic treatment. Molecules present before and after hydroponics were defined as resistant molecules; molecules present before hydroponics but absent after hydroponics were defined as removed molecules; and molecules absent before hydroponics but present after hydroponics were defined as produced molecules. Large lignin molecules were broken down into more unsaturated molecules, but lignins were the most commonly resistant, removed, and produced molecules. Correlation analysis revealed that N- or S-bearing molecules were phytotoxic in the AP. Tannins positively influenced the growth of pak choi. These results provide new insights into potential implementation strategies for liquid fertilizers produced from AP arising from HTC of MS and agricultural wastes.
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Agricultura , Aguas del Alcantarillado , Agricultura/métodos , Brassica/crecimiento & desarrollo , Eliminación de Residuos Líquidos/métodosRESUMEN
Livestock manure is often contaminated with heavy metals (HMs) and HM resistance genes (HMRGs), which pollute the environment. In this study, we aimed to investigate the effects of the aqueous phase (AP) produced by hydrothermal carbonization (HTC) of sewage sludge (SS) alone and the AP produced by co-HTC of rice husk (RH) and SS (RH-SS) on humification, HM bioavailability, and HMRGs during chicken manure composting. RH-SS and SS increased the humic acid content of the compost products by 18.3 % and 9.7 %, respectively, and significantly increased the humification index (P < 0.05) compared to the CK (addition of tap water). The passivation of HMs (Zn, Cu, As, Pb, and Cr) increased by 12.17-23.36 % and 9.74-15.95 % for RH-SS and SS, respectively, compared with that for CK. RH-SS and SS reduced the HMRG abundance in composted products by 22.29 % and 15.07 %, respectively. The partial least squares path modeling results showed that SS and RH-SS promoted compost humification while simultaneously altering the bacterial community and reducing the bioavailability of metals and host abundance of HMRGs, which has a direct inhibitory effect on the production and distribution of HMRGs. These findings support a new strategy to reduce the environmental risk of HMs and HMRGs in livestock manure utilization.
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Pollos , Compostaje , Estiércol , Metales Pesados , Aguas del Alcantarillado , Animales , Metales Pesados/toxicidad , Sustancias Húmicas/análisis , Carbono/química , Contaminantes del Suelo/toxicidad , Oryza/metabolismoRESUMEN
The effects of aqueous phases (AP) formed from hydrothermal carbonation of sewage sludge (with or without rice husk) as moisture regulators of nitrogen metabolism pathways during composting are currently unclear. Macrogenomic analyses revealed that both APs resulted in notably changes in bacterial communities during composting; increased levels of nitrogen assimilation, nitrification, and denitrification metabolic pathways; and decreased levels of nitrogen mineralization metabolic pathways. Genes associated with nitrogen assimilation and mineralization accounted for 34-41% and 32-40% of the annotated reads related to nitrogen cycling during composting, respectively, representing them as the most abundant nitrogen metabolism processes. The gudB and norB were identified as key genes for nitrogen mineralization and nitrous oxide emission, respectively. This research offers a better understanding of the effects of additional nitrogen sources on nitrogen metabolism pathways during composting.
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Hydrothermal carbonization (HTC) is a promising carbon-neutral technology for converting sewage sludge (SS) and agricultural waste into energy. However, HTC-generated aqueous phase (AP) impedes the development of the former. This study investigated the potential of SS with rice husk (RH) and wheat straw (WS) co-HTC to form hydrochar and AP as substitutes for fuel and chemical fertilizer, respectively. Compared with single SS hydrochar, the yield of co-HTC-based hydrochar and higher heating value significantly increased by 10.9%-21.6% and 4.2%-182.7%, reaching a maximum of 72.6% and 14.7 MJ/kg, respectively. Co-HTC improves the safe handling, storage and transportation, and combustion performance of hydrochar. The total nitrogen concentration in AP-SS was 2575 mg/L, accounting for 67.7% of that found in SS. Co-HTC decreased and increased the amine and phenolic components of AP, respectively. AP-SS-RH and AP-SS-WS significantly increased pakchoi dry weight by 45.5% and 49.4%, respectively, compared with AP-SS. The results of the hydroponic experiments with AP instead of chemical fertilizers revealed that AP-SS did not reduce pakchoi dry weight by replacing <20% chemical fertilizers. However, AP-SS-RH or AP-SS-WS replaced 60% chemical fertilizers. Therefore, the co-HTC of SS and agricultural waste increased the AP substitution of chemical fertilizer from 20% to 60%. These findings suggest that the co-HTC of agricultural waste with SS is a promising technology for converting SS into renewable resource products for fuels and N-rich liquid fertilizer while significantly improving fuel and fertilizer quality.
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Fertilizantes , Oryza , Aguas del Alcantarillado , Mejoramiento de la Calidad , Agricultura , TriticumRESUMEN
Due to various geological, hydrogeological conditions and human activities, groundwater of different regions has distinct hydrochemical characteristics. The harmful chemical components of groundwater affect human health, and thus, the groundwater quality health risk assessment (GQHR) is important to local residents. It is vital to select GQHR factors combined with hydrochemical features, and to explore their formation, concentration characteristics and the prominent controlling role of influencing risk distribution from natural and human reasons. The factors of NO3-, NO2-, NH4+ and F- were extracted as assessment factors to evaluate the GQHR. The factors NO3-, NO2- and NH4+ are derived by human activities and F- stems from irrigation of geogenic high-fluoride groundwater and fertilizer use. The results of GQHR showed the risk order as children > adult females > adult males. The low- and medium-risk regions correspond to high groundwater levels, which are mainly controlled by natural factors. The high-risk regions located in eastern part of the study area, which were affected by both natural and human reasons. The targeted measures to prevent the increase of groundwater health risk caused by different dominant controlling effects were put forward. The research provides a scientific basis for the safety of groundwater supply and environmental exposure in this area. The research ideas and methods can be a reference for similar studies.
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Agua Subterránea , Contaminantes Químicos del Agua , Adulto , Masculino , Niño , Femenino , Humanos , Monitoreo del Ambiente/métodos , Dióxido de Nitrógeno , Contaminantes Químicos del Agua/toxicidad , Contaminantes Químicos del Agua/análisis , Calidad del Agua , Medición de Riesgo , ChinaRESUMEN
Hydrothermal carbonization (HTC) has been recognized as a promising sewage sludge (SS) treatment technology for effective pathogen elimination, bioenergy recovery, organic contaminant destruction and volume reduction. However, the solid product (hydrochar) of SS after HTC as fuel has the problems of high ash content, high nitrogen content and low calorific value. The aqueous phase (AP) produced is still considered a burden and has become a bottleneck in the development of HTC. In this study, co-HTC of SS with spent mushroom substrate (SMS) is conducted, and the fuel properties of hydrochar and the quality of the AP as a liquid fertilizer are investigated. In comparison with hydrochar of single SS, the energy yield and higher heating value of the hydrochar from co-HTC were significantly increased by 12.1-44.8 % and 33.2-137.8 %, respectively, reaching their maximum of 72.75 % and14.98 MJ/kg, respectively. Co-HTC can improve safe handling, storage and transportation, and combustion performance of hydrochar. Furthermore, the AP of co-HTC could significantly increase the biomass of pakchoi, which was 140.9 % and 90.7 % of AP from single SS and Hoagland nutrition solution (represents commercial fertilizer), respectively. The AP of co-HTC as fertilizer can recover 62.03-64.65 % nitrogen from SS and SMS. These findings suggest that co-HTC of SMS with SS is a promising technology for the conversion SS into renewable resource products for fuels and N-rich liquid fertilizer while also significantly improving fuel and fertilizer quality.
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Agaricales , Aguas del Alcantarillado , Fertilizantes , Carbono , Nitrógeno , NutrientesRESUMEN
Hydrothermal technology (HT) has received much attention in recent years as a process to convert wet organic waste into hydrochar. The aqueous phase (HTAP) produced by this process is still a burden and has become a bottleneck issue for HT process development. In this study, we provide the first investigation of the HTAP characteristics, phytotoxicity, and their correlation with persulfate (PS) (PS, 2.0 mmol/g TS)-assisted municipal sludge HT. The results showed that PS accelerated the hydrolysis of protein substances and increased the concentration of NH4+ by 13.4% to 190.5% and that of PO43- by 24.2% to 1103.7% in HTAP at hydrothermal temperatures of 120 to 240 °C. PS can reduce the phytotoxicity of HTAP by reducing aldehydes, ketones, N heterocyclic compounds, and particle size and by increasing its humification index. The maximum values of the root length and biomass of pakchoi (Brassica chinensis L.) seedlings occurred when electrical conductivity was 0.2 mS/cm of HTAP. This work provided a new strategy for the selection and design of HTAP management strategies.
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Aguas del Alcantarillado , Toxinas Biológicas , Hidrólisis , Biomasa , TemperaturaRESUMEN
BACKGROUND: Ileocolonoscopy (IC) detects mucosal inflammation and magnetic resonance enterography (MRE) detects transmural inflammation in Crohn disease (CD). We aimed to evaluate the relationship between the simplified magnetic resonance index of activity (MARIAs) and measures of inflammation by IC in children with newly diagnosed CD. METHODS: Retrospective review of 140 patients 6-18âyears of age with CD who had baseline IC and MRE within 5âweeks of diagnosis. MARIAs was calculated for each intestinal segment (terminal ileum [TI], ascending colon, transverse colon, descending colon, sigmoid colon, rectum), defined as (1â×âthickness > 3âmm)â+â(1â×âedema)â+â(1â×âfat stranding)â+â(2â×âulcers). Sensitivity and specificity were derived using receiver operating characteristic (ROC) curves to compare MARIAs to IC findings. RESULTS: Using IC as the reference standard, the cutoff MARIAs ≥1 identified TI segments with active inflammation with 84% sensitivity, 73% specificity, 85% positive predictive value (PPV), 70% negative predictive value (NPV), and area under the curve (AUC) 0.782 (95% confidence interval [CI] 0.689-0.876). The cutoff MARIAs ≥2 identified TI segments with severe lesions with 87% sensitivity, 76% specificity, 87% PPV, 76% NPV, and AUC 0.814 (95% CI 0.712-0.916). There was poor sensitivity for all colonic segments. CONCLUSION: The MARIAs is feasible and accurate in reflecting disease activity in the TI, but not in the colon, in children with newly diagnosed CD. Although the MARIAs may be useful for monitoring TI disease activity over time, full assessment continues to require both IC and MRE.
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Enfermedades del Colon , Enfermedad de Crohn , Niño , Colon Sigmoide , Enfermedades del Colon/patología , Enfermedad de Crohn/diagnóstico , Enfermedad de Crohn/diagnóstico por imagen , Humanos , Íleon/diagnóstico por imagen , Íleon/patología , Lactante , Inflamación/patología , Imagen por Resonancia Magnética , Espectroscopía de Resonancia MagnéticaRESUMEN
OBJECTIVES: Corticosteroid treatment of paediatric leukaemia patients can lead to osteonecrosis (ON). We determined whether bone marrow oedema (BME) is an early sign of progressive ON and eventual bone collapse. METHODS: In a retrospective study, two radiologists reviewed MR imaging characteristics of 47 early stage epiphyseal ON in 15 paediatric and adolescent leukaemia patients. Associations between BME on initial imaging studies and subchondral fracture, disease progression and bone collapse were assessed by Cochran-Mantel-Haenszel tests. Differences in time to progression and bone collapse between lesions with and without oedema were assessed by log rank tests. RESULTS: Forty-seven occurrences of ON were located in weight bearing joints, with 77% occurring in the femur. Seventeen lesions progressed to collapse, two lesions worsened without collapse, and 28 remained stable or improved. BME was significantly associated with subchondral fracture (p = 0.0014), disease progression (p = 0.0015), and bone collapse (p < 0.001), with a sensitivity and specificity of 94% and 77%, respectively, for bone collapse. Time to progression for ON with oedema was 2.7 years (95% CI: 1.7-3.4); while the majority of no-oedema ON were stable (p = 0.0011). CONCLUSIONS: BME is an early sign of progressive ON and eventual bone collapse in paediatric and adolescent leukaemia patients. KEY POINTS: ⢠Bone marrow oedema in corticosteroid-induced osteonecrosis predicts progression to bone collapse. ⢠Bone marrow oedema is associated with subchondral fractures in corticosteroid-induced osteonecrosis. ⢠Bone marrow oedema can be used to stratify patients to joint-preserving interventions. ⢠Absence of bone marrow oedema can justify a "wait and watch" approach.
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Enfermedades de la Médula Ósea/patología , Médula Ósea/patología , Edema/patología , Fracturas Espontáneas/etiología , Glucocorticoides/efectos adversos , Leucemia/complicaciones , Osteonecrosis/inducido químicamente , Adolescente , Enfermedades de la Médula Ósea/complicaciones , Niño , Preescolar , Progresión de la Enfermedad , Edema/complicaciones , Femenino , Fémur/patología , Fracturas Espontáneas/diagnóstico , Glucocorticoides/uso terapéutico , Humanos , Leucemia/tratamiento farmacológico , Imagen por Resonancia Magnética/métodos , Masculino , Osteonecrosis/complicaciones , Osteonecrosis/diagnóstico , Pronóstico , Estudios Retrospectivos , Adulto JovenRESUMEN
PURPOSE: To develop a fast and robust method to resolve phase ambiguity in dual-echo Dixon imaging. METHODS: A major challenge in dual-echo Dixon imaging is to estimate the phase error resulting from field inhomogeneity. In this work, a binary quadratic optimization program was formulated to resolve the phase ambiguity. A projected power method was developed to efficiently solve the optimization problem. Both the 1-peak fat model and 6-peak fat model were applied to three-dimensional (3D) datasets. Additionally, the proposed method was extended to dynamic magnetic resonance imaging (MRI) applications using the 6-peak fat model. With institutional review board (IRB) approval and patient consent/assent, the proposed method was evaluated and compared with region growing on 29 consecutive 3D high-resolution patient datasets. RESULTS: Fast and robust water/fat separation was achieved by the proposed method in different representative 3D datasets and dynamic 3D datasets. Superior water/fat separation was achieved using the 6-peak fat model compared with the 1-peak fat model. Compared to region growing, the proposed method reduced water/fat swaps from 76 to 7% of the patient cohort. CONCLUSION: The proposed method can achieve fast and robust phase error estimation in dual-echo Dixon imaging. Magn Reson Med 77:2066-2076, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Procesamiento de Imagen Asistido por Computador/métodos , Imagenología Tridimensional/métodos , Imagen por Resonancia Magnética/métodos , Adolescente , Adulto , Algoritmos , Artefactos , Niño , Preescolar , Simulación por Computador , Humanos , Lactante , Persona de Mediana Edad , Modelos EstadísticosRESUMEN
PURPOSE: To develop and clinically evaluate a pediatric knee magnetic resonance imaging (MRI) technique based on volumetric fast spin-echo (3DFSE) and compare its diagnostic performance, image quality, and imaging time to that of a conventional 2D protocol. MATERIALS AND METHODS: A 3DFSE sequence was modified and combined with a compressed sensing-based reconstruction resolving multiple image contrasts, a technique termed T2 Shuffling (T2 Sh). With Institutional Review Board (IRB) approval, 28 consecutive children referred for 3T knee MRI prospectively underwent a standard clinical knee protocol followed by T2 Sh. T2 Sh performance was assessed by two readers blinded to diagnostic reports. Interpretive discrepancies were resolved by medical record chart review and consensus between the readers and an orthopedic surgeon. Image quality was evaluated by rating anatomic delineation, with 95% confidence interval. A Wilcoxon rank-sum test assessed the null hypothesis that T2 Sh structure delineation compared to conventional 2D is unchanged. Intraclass correlation coefficients were calculated for interobserver agreement. Imaging time of the conventional protocol and T2 Sh was compared. RESULTS: There was 81% and 87% concordance between T2 Sh reports and diagnostic reports, respectively, for each reader. Upon consensus review, T2 Sh had 93% sensitivity and 100% specificity compared to clinical reports for detection of clinically relevant findings. The 95% confidence interval of diagnostic or better rating was 95-100%, with 34-80% interobserver agreement. There was no significant difference in structure delineation between T2 Sh and 2D, except for the retinaculum (P < 0.05), where 2D was preferred. Typical imaging time for T2 Sh and the conventional exam was 7 and 13 minutes, respectively. CONCLUSION: A single-sequence pediatric knee exam is feasible with T2 Sh, providing multiplanar, reformattable 4D images. LEVEL OF EVIDENCE: 2 J. MAGN. RESON. IMAGING 2017;45:1700-1711.
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Interpretación de Imagen Asistida por Computador/métodos , Imagenología Tridimensional/métodos , Articulación de la Rodilla/diagnóstico por imagen , Articulación de la Rodilla/patología , Imagen por Resonancia Magnética/métodos , Procesamiento de Señales Asistido por Computador , Adolescente , Algoritmos , Femenino , Humanos , Aumento de la Imagen/métodos , Masculino , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
Yuqiao Reservoir, an important adjusting reservoir in the project of diverting water from the Luanhe River to Tianjin City, is an important water resource for Tianjin City. Concentrations and spatial variation characteristics of Cd, As, Pb, Cu, Cr, and Zn from 33 sub watershed sampling sites of Yuqiao reservoir and the relationship to landscape pattern were discussed. The result showed that average concentrations of Cd, As, Cu, Cr in suspended particulate matter were higher than Chinese environmental quality standard Grade one for soils, and there were ecological risks for them because they could arrive at Yuqiao reservoir. The average concentrations of Cd, As, Pb, Cu, Cr, and Zn in surface sediments were 0.32 mg·kg-1, 30.39 mg·kg-1, 33.49 mg·kg-1, 58.20 mg·kg-1, 90.16 mg·kg-1 and 94.80 mg·kg-1 respectively. The average concentrations of Cd, As, Cu and the concentrations of Pb, Cr, Zn in partial samples exceeded Chinese environmental quality standard Grade one for soils. The average concentrations of Cd, Cr, Zn in surface sediments of three tributaries increased in the order of Linhe River >Shahe River >Lihe Rier, Cu decreased in the order of Linhe River < Shahe River < Lihe River, and As, Pb increased in the order of Shahe River >Linhe River >Lihe Ricer. Land use types in Yuqiao reservoir basin had some impact on the distribution of heavy metal concentrations in river surface sediments. Woodland and shrub grass land determined the natural distribution trend of heavy metals in surface sediments. Gardenland and industrial & mining land usage had impact on Cd, As, Pb, Cr distributions. Farmland and village & town land usage did not produce negative influence on heavy metal distribution.
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In this report, we studied the optical properties of hybrid spherical structures consisting of alternating nanosheets of titania (TiO(2)) and graphene oxide (GO) prepared by a layer-by-layer self-assembly technique. Compared to samples with only TiO(2) spheres or GO nanosheets, a blue-to-red light emission band emerges and persists in this novel composite material even after it was further reduced through microwave irradiation. From detailed time-resolved measurements and energy-level structure modeling, this unexpected fluorescent feature was attributed to the indirect optical transitions between TiO(2) and the localized sp(2) domains of GO in a charge-separated configuration.
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Grafito/química , Membranas Artificiales , Modelos Químicos , Nanopartículas/química , Nanopartículas/ultraestructura , Titanio/química , Simulación por Computador , Luz , Óxidos/química , Tamaño de la Partícula , Dispersión de RadiaciónRESUMEN
Microalgal oil was encapsulated in gelatin-gum Arabic complex coacervated matrices using transglutaminase (TG) as cross-linking agent. The effects of various cross-linking parameters including hardening time, temperature, pH and TG concentration on the oil release rate of the complex coacervation microcapsules (CCMs) were investigated, with sodium dodecyl sulfate (SDS) as release medium. The optimum parameters were as follows: hardening for 6h at 15°C and pH 6.0 with TG concentration of 15 U/g gelatin. The microcapsules obtained under optimum conditions had the lowest oil release rate. By analyzing the oil release curves, it was found that the oil release rate did not exactly fit the modified first-order kinetic model but exhibited early time and late time approximations for unsteady state diffusion. A greater initial release of oil was clearly observed whatever cross-linking parameters were, while the release profile became constant indicating some sustained release after the first hour.
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Microalgas/química , Aceites de Plantas/administración & dosificación , Difusión , Concentración de Iones de Hidrógeno , Microscopía Electrónica de Rastreo , Tamaño de la Partícula , Aceites de Plantas/farmacocinética , Dodecil Sulfato de Sodio/químicaRESUMEN
Sodium caseinate (SC) cross-linked by microbial transglutaminase (MTGase) for encapsulating microalgal oil was investigated. Protein cross-linking was evidenced in the SDS-PAGE graph. The emulsifying properties of SC depended on the cross-linked time with MTGase. The emulsifying activity and stability indexes of SC increased with the cross-linking time of 30 to 90 min (P30 to P90), and then declined with longer cross-linked time of 180 to 420 min (P180 to P420). The P30 to P90 as wall material for microencapsulation was superior to P180 to P420 and control sample. The microcapsules prepared with P30 to P90 showed more than 97% of microencapsulation efficiency in contrast to about 90% with the P180 to P420. During storage, the microcapsules prepared with P30 to P90 exhibited higher oxidative stability as compared with other microcapsules. A sustained release of microalgal oil was observed, and core release was time dependent and affected by cross-linking degree. Results showed that the powdered microalgal oil prepared with P30 to P90 demonstrated enhanced physicochemical properties and oxidative stability. Practical Application: The novel method using cross-linked proteins as wall material induced by microbial transglutaminase in food industry for sensitive ingredients could convert microcapsules into a stable form, which would lead to its more widespread utilization as a kind of food additive.
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Caseínas/química , Caseínas/metabolismo , Tecnología de Alimentos , Microalgas/química , Aceites/química , Polímeros/química , Polímeros/metabolismo , Transglutaminasas/metabolismo , Cápsulas , Fenómenos Químicos , Preparaciones de Acción Retardada , Electroforesis en Gel de Poliacrilamida , Emulsionantes/química , Emulsionantes/metabolismo , Emulsiones , Ácidos Grasos Omega-3/administración & dosificación , Alimentos Fortificados/análisis , Peróxidos Lipídicos/análisis , Peso Molecular , Oxidación-Reducción , Polisacáridos/química , Solubilidad , Factores de TiempoRESUMEN
The present studies were done to investigate the effect of long-term nicotine treatment against nigrostriatal damage in non-human primates. Monkeys were administered nicotine in drinking water for 6 months to provide chronic but intermittent delivery as with smoking. Plasma nicotine levels ranged from 10 to 15 ng/mL, which were within the range in cigarette smokers. Animals were then lesioned with low doses of the dopaminergic neurotoxin MPTP for several months while nicotine was continued. The results showed that levels of striatal tyrosine hydroxylase, dopamine transporter, vesicular monoamine transporter, dopamine and nicotinic receptors were greater in nicotine-treated MPTP-lesioned primates than in lesioned animals not receiving nicotine. Nicotine had no effect in unlesioned animals. Monoamine oxidase activity was similar in unlesioned and lesioned animals treated with or without nicotine, suggesting that nicotine did not exert its effects through changes in MPTP or dopamine metabolism. MPTP-induced cell loss in the substantia nigra was unaffected by nicotine treatment, indicating that nicotine acts at the striatal level to restore/maintain dopaminergic function. These data further support the possibility that nicotine contributes to the lower incidence of Parkinson's disease in smokers.