Herbicide sensitivity determinant of wheat plastid acetyl-CoA carboxylase is located in a 400-amino acid fragment of the carboxyltransferase domain

A series of chimeral genes, consisting of the yeast GAL10 promoter, yeast ACC1 leader, wheat acetyl-CoA carboxylase (ACCase; EC 6.4.1.2) cDNA, and yeast ACC1 3'-tail, was used to complement a yeast ACC1 mutation. These genes encode a full-length plastid enzyme, with and without the putative chloroplast transit peptide, as well as five chimeric cytosolic/plastid proteins. Four of the genes, all containing at least half of the wheat cytosolic ACCase coding region at the 5'-end, complement the yeast mutation. Aryloxyphenoxypropionate and cyclohexanedione herbicides, at concentrations below 10 microM, inhibit the growth of haploid yeast strains that express two of the chimeric ACCases. This inhibition resembles the inhibition of wheat plastid ACCase observed in vitro and in vivo. The differential response to herbicides localizes the sensitivity determinant to the third quarter of the multidomain plastid ACCase. Sequence comparisons of different multidomain and multisubunit ACCases suggest that this region includes part of the carboxyltransferase domain, and therefore that the carboxyltransferase activity of ACCase (second half-reaction) is the target of the inhibitors. The highly sensitive yeast gene-replacement strains described here provide a convenient system to study herbicide interaction with the enzyme and a powerful screening system for new inhibitors.     

Gastrointestinal hypomotility with loss of enteric nicotinic acetylcholine receptors: active immunization model in mice

Background Autoimmune gastrointestinal dysmotility (AGID) is a limited form of dysautonomia. The only proven effector to date is IgG specific for ganglionic nicotinic‐acetylcholine receptors containing α3 subunits [α3*‐ nicotinic acetylcholine receptor (nAChR)]. Rabbits immunized with recombinant α3‐polypeptide produce α3*‐nAChR autoantibodies, and profound AGID ensues. Human and rabbit α3*‐nAChR‐specific‐IgGs induce transient hypomotility when injected into mice. Here, we describe success and problems encountered inducing gastrointestinal hypomotility in mice by active immunization. Methods We repeatedly injected young adult mice of seven different strains susceptible to autoimmunity (spontaneous diabetes or neural antigen immunization‐induced myasthenia gravis or encephalomyelitis) with: (i) α3‐polypeptide, intradermally or (ii) live α3*‐nAChR‐expressing xenogeneic cells, intraperitoneally. We measured serum α3*‐nAChR‐IgG twice monthly, and terminally assessed blue dye gastrointestinal transit, total small intestinal α3*‐nAChR content (radiochemically) and myenteric plexus neuron numbers (immunohistochemically, ileal–jejunal whole‐mount preparations). Key Results Standard cutaneous inoculation with α3‐polypeptide was minimally immunogenic, regardless of dose. Intraperitoneally injected live cells were potently immunogenic. Self‐reactive α3*‐nAChR‐IgG was induced only by rodent immunogen; small intestinal transit slowing and enteric α3*‐nAChR loss required high serum levels. Ganglionic neurons were not lost. Conclusions & Inferences Autoimmune gastrointestinal dysmotility is inducible in mice by active immunization. Accompanying enteric α3*‐nAChR reduction without neuronal death is consistent with an IgG‐mediated rather than T cell‐mediated pathogenesis, as is improvement of symptoms in patients receiving antibody‐depleting therapies.     

A bibliography of cost-effectiveness practices in physical medicine and rehabilitation: AAPM&R white paper

Cost-effectiveness studies attempt to determine the ratio of costs to outcomes of a particular intervention or treatment and to compare a standard intervention with an alternative intervention to determine if the alternative is more cost effective. The goal is to establish priorities for the resources allocation and to decide among alternative interventions for the same medical condition. The global process of rehabilitation does not usually lend itself to cost-effective analysis (due to the complex set of treatments provided) but rather to specific interventions and specific aspects of outcome. The American Academy of Physical Medicine and Rehabilitation has published a cost effectiveness annotated bibliography on the Internet (http://www.aapmr.org/memphys/cebfinala.htm) that identifies 132 studies in the literature that meet specified criteria and are related to the field of rehabilitation. This White Paper attempts to interpret and synthesize the studies in that bibliography that relate to stroke, spinal cord injury (SCI), orthopedic conditions, pain syndromes, amputations, and traumatic brain injury (TBI). Most studies support the cost effectiveness of care for stroke and SCI in dedicated units or centers rather than in a general medical unit. Studies also support back programs and revascularization procedures in limb ischemia. Studies in TBI underscore the significant financial resources for the care of these patients as well as the potential benefit from rehabilitation services even in the most severely injured. Further high quality research in this area is needed.     

Allergy,total serum immunoglobulin E,and airflow in children and adolescents in TENOR

Haselkorn T, Szefler SJ, Simons FER, Zeiger RS, Mink DR, Chipps BE, Borish L, Wong DA, for the TENOR Study Group. Allergy, total serum immunoglobulin E, and airflow in children and adolescents in TENOR.
Pediatr Allergy Immunol 2010: 21: 1157–1165.
© 2010 John Wiley & Sons A/S In children and adolescents with difficult‐to‐treat asthma, few data exist characterizing the relationships between basic patient characteristics (e.g., age, sex) and atopic indicators in asthma. These associations were examined in The Epidemiology and Natural History of Asthma: Outcomes and Treatment Regimens (TENOR), an observational study of a large cohort of patients with severe or difficult‐to‐treat asthma. To characterize allergy patterns and the relationship between total serum immunoglobulin E (IgE) and airflow in young patients with severe or difficult‐to‐treat asthma. A total of 1261 patients from the TENOR study were stratified into four age groups at baseline (6–8, 9–11, 12–14, and 15–17 yr). The objective was to characterize allergy patterns and the relationship between total serum immunoglobulin E (IgE) and ratio of pre‐bronchodilator forced expiratory volume in 1 second to forced vital capacity (FEV₁/FVC) in young patients with severe or difficult‐to‐treat asthma. The chi‐square test for categorical variables and analysis of variance for continuous variables were used to identify significant differences among age groups. Multivariable linear regression was used to evaluate the association between IgE and FEV₁/FVC. Allergic rhinitis was reported in approximately two‐thirds of patients. Up to 25% of patients had atopic dermatitis, which differed across age groups in boys (p < 0.05). Positive allergen skin test rate differed across age groups in boys (p < 0.05). Rates of asthma triggers were higher and differed across age groups in girls (p < 0.05), particularly around menarche (12–14 yr). IgE levels were higher in boys and differed across age groups in boys (p < 0.01) and girls (p < 0.05). IgE was associated with a lower FEV₁/FVC after adjusting for age and sex (p < 0.01). Severe or difficult‐to‐treat asthma in children and adolescents is characterized by high frequencies of comorbid allergic diseases, allergen sensitization, and high IgE levels. This burden is amplified by the association of more airflow limitation with higher IgE levels, suggesting the need for allergy evaluations.     

Growth of Toxoplasma gondii is inhibited by aryloxyphenoxypropionate herbicides targeting acetyl-CoA carboxylase

Aryloxyphenoxypropionates, inhibitors of the plastid acetyl-CoA carboxylase (ACC) of grasses, also inhibit Toxoplasma gondii ACC. Clodinafop, the most effective of the herbicides tested, inhibits growth of T. gondii in human fibroblasts by 70% at 10 microM in 2 days and effectively eliminates the parasite in 2-4 days at 10-100 microM. Clodinafop is not toxic to the host cell even at much higher concentrations. Parasite growth inhibition by different herbicides is correlated with their ability to inhibit ACC enzyme activity, suggesting that ACC is a target for these agents. Fragments of genes encoding the biotin carboxylase domain of multidomain ACCs of T. gondii, Plasmodium falciparum, Plasmodium knowlesi, and Cryptosporidium parvum were sequenced. One T. gondii ACC (ACC1) amino acid sequence clusters with P. falciparum ACC, P. knowlesi ACC, and the putative Cyclotella cryptica chloroplast ACC. Another sequence (ACC2) clusters with that of C. parvum ACC, probably the cytosolic form.     

Factors predicting satisfactory home care after stroke

This study prospectively investigated factors predicting optimal poststroke home care. One hundred and thirty-five first occurrence stroke patients and their primary support persons were evaluated during the initial hospitalization after stroke and again one year poststroke. Discriminant function analysis was used to identify two groups from the baseline data: home care situations which were rated optimal and those which were not. Group membership was predicted and validated with 72.6% accuracy. Patients at risk for less than optimal home care had caregivers who were (1) more likely to be depressed, (2) less likely to be married to the patient, (3) below average in knowledge about stroke care, and (4) reporting more family dysfunction. Our findings suggest that caregiver-related problems can have a collective effect on rehabilitation outcome and that treatment should reduce caregiver depression, minimize family dysfunction, and increase the family's knowledge about stroke care.     

Single-site mutations in the carboxyltransferase domain of plastid acetyl-CoA carboxylase confer resistance to grass-specific herbicides

Grass weed populations resistant to aryloxyphenoxypropionate (APP) and cyclohexanedione herbicides that inhibit acetyl-CoA carboxylase (ACCase; EC 6.4.1.2) represent a major problem for sustainable agriculture. We investigated the molecular basis of resistance to ACCase-inhibiting herbicides for nine wild oat (Avena sterilis ssp. ludoviciana Durieu) populations from the northern grain-growing region of Australia. Five amino acid substitutions in plastid ACCase were correlated with herbicide resistance: Ile-1,781-Leu, Trp-1,999-Cys, Trp-2,027-Cys, Ile-2,041-Asn, and Asp-2,078-Gly (numbered according to the Alopecurus myosuroides plastid ACCase). An allele-specific PCR test was designed to determine the prevalence of these five mutations in wild oat populations suspected of harboring ACCase-related resistance with the result that, in most but not all cases, plant resistance was correlated with one (and only one) of the five mutations. We then showed, using a yeast gene-replacement system, that these single-site mutations also confer herbicide resistance to wheat plastid ACCase: Ile-1,781-Leu and Asp-2,078-Gly confer resistance to APPs and cyclohexanediones, Trp-2,027-Cys and Ile-2,041-Asn confer resistance to APPs, and Trp-1,999-Cys confers resistance only to fenoxaprop. These mutations are very likely to confer resistance to any grass weed species under selection imposed by the extensive agricultural use of the herbicides.     

Recombinant yeast screen for new inhibitors of human acetyl-CoA carboxylase 2 identifies potential drugs to treat obesity

Acetyl-CoA carboxylase (ACC) is a key enzyme of fatty acid metabolism with multiple isozymes often expressed in different eukaryotic cellular compartments. ACC-made malonyl-CoA serves as a precursor for fatty acids; it also regulates fatty acid oxidation and feeding behavior in animals. ACC provides an important target for new drugs to treat human diseases. We have developed an inexpensive nonradioactive high-throughput screening system to identify new ACC inhibitors. The screen uses yeast gene-replacement strains depending for growth on cloned human ACC1 and ACC2. In “proof of concept” experiments, growth of such strains was inhibited by compounds known to target human ACCs. The screen is sensitive and robust. Medium-size chemical libraries yielded new specific inhibitors of human ACC2. The target of the best of these inhibitors was confirmed with in vitro enzymatic assays. This compound is a new drug chemotype inhibiting human ACC2 with 2.8 μM IC₅₀ and having no effect on human ACC1 at 100 μM.