Measurements of glial metabolic fluxes with C-11-acetate using positron emission and an adapted NMR-based metabolic modeling approach

Objectives: Acetate brain metabolism has the particularity to occur specifically in glial cells. Labeling studies, using acetate labeled either with 13C (NMR) or 11C (PET), are governed by the same biochemical reactions and thus follow the same mathematical principles. In this study, the objective was to adapt an NMR acetate brain metabolism model to analyse [1-11C]acetate infusion in rats. Methods: Brain acetate infusion experiments were modeled using a two-compartment model approach used in NMR.1-3 The [1-11C]acetate labeling study was done using a beta scintillator.4 The measured radioactive signal represents the time evolution of the sum of all labeled metabolites in the brain. Using a coincidence counter in parallel, an arterial input curve was measured. The 11C at position C-1 of acetate is metabolized in the first turn of the TCA cycle to the position 5 of glutamate (Figure 1A). Through the neurotransmission process, it is further transported to the position 5 of glutamine and the position 5 of neuronal glutamate. After the second turn of the TCA cycle, tracer from [1-11C]acetate (and also a part from glial [5-11C]glutamate) is transferred to glial [1-11C]glutamate and further to [1-11C]glutamine and neuronal glutamate through the neurotransmission cycle. Brain poster session: oxidative mechanisms S460 Journal of Cerebral Blood Flow & Metabolism (2009) 29, S455-S466 Results: The standard acetate two-pool PET model describes the system by a plasma pool and a tissue pool linked by rate constants. Experimental data are not fully described with only one tissue compartment (Figure 1B). The modified NMR model was fitted successfully to tissue time-activity curves from 6 single animals, by varying the glial mitochondrial fluxes and the neurotransmission flux Vnt. A glial composite rate constant Kgtg=Vgtg/[Ace]plasma was extracted. Considering an average acetate concentration in plasma of 1 mmol/g5 and the negligible additional amount injected, we found an average Vgtg = 0.08±0.02 (n = 6), in agreement with previous NMR measurements.1 The tissue time-activity curve is dominated by glial glutamate and later by glutamine (Figure 1B). Labeling of neuronal pools has a low influence, at least for the 20 mins of beta-probe acquisition. Based on the high diffusivity of CO2 across the blood-brain barrier; 11CO2 is not predominant in the total tissue curve, even if the brain CO2 pool is big compared with other metabolites, due to its strong dilution through unlabeled CO2 from neuronal metabolism and diffusion from plasma. Conclusion: The two-compartment model presented here is also able to fit data of positron emission experiments and to extract specific glial metabolic fluxes. 11C-labeled acetate presents an alternative for faster measurements of glial oxidative metabolism compared to NMR, potentially applicable to human PET imaging. However, to quantify the relative value of the TCA cycle flux compared to the transmitochondrial flux, the chemical sensitivity of NMR is required. PET and NMR are thus complementary.

Secondary Cancer Risk for Stage I Seminoma Patients - a Comparison of Adjuvant Treatment Versus Surveillance

Background: Post-surgical management of stage I seminoma includes: surveillance with repeated CT-scans and treatment reserved for those who relapse, or adjuvant treatment with either immediate radiation therapy (RT) or carboplatin. The cancer specific survival is close to 100%. Cure without long-term sequelae of treatment is the aim. Our goal is to estimate the risk of radiation-induced secondary cancers (SC) death from for patients undergoing S, adjuvant RT or adjuvant carboplatin (AC).Materials and Methods: We measured organ doses from CT scans (3 phases each one) of a seminoma patient who was part of the active surveillance strategy and from a man undergoing adjuvant RT 20-Gy and a 30-Gy salvage RT treatment to the para-aortic area using helical Intensity Modulated RT (Tomotherapy®) with accurate delineation of organs at risk and a CTV to PTV expansion of 1 cm. Effective doses to organs in mSv were estimated according to the tissue-weighting factors recommendations of the International Commission on Radiological Protection 103 (Ann ICRP 2007). We estimated SC incidence and mortality for a 10,000 people population based on the excess absolute risk model from the Biological Effects of Ionizing Radiation (BEIR) VII (Health Risk of Exposure to Low Levels of Ionizing Radiation, NCR, The National Academies Press Washington, DC, 2006) assuming a seminoma diagnosis at age 30, a total life expectancy of 80 years.Results: The nominal risk for a fatal secondary cancers was calculated 1.5% for 15 abdominal CT scans, 14.8% for adjuvant RT (20 Gy paraaortic field) and 22.2% for salvage RT (30 Gy). The calculation assumed that the risk of relapse on surveillance and adjuvant AC was 15% and 4% respectively and that all patients were salvaged at relapse with RT. n CT abdomen/Pelvis = secondary cancer % RT Dose and % receiving treatment = secondary cancer % Total secondary cancer risk in % Active surveillance 15 = 1.5% 30 Gy in 15% of pts = 3.3% 4.8 Adjuvant carboplatin 7 = 0.7% 30 Gy in 4% of pts = 0.88% 1.58 Adjuvant radiotherapy 7 = 0.7% 20 Gy in 100% of pts = 14.8% 15.5Conclusions: These data suggest that: 1) Adjuvant radiotherapy is harmful and should not anymore be regarded as a standard option for seminoma stage I. 2) AC seems to be an option to reduce radiation induced cancers. Limitations: the study does not consider secondary cancers due to chemotherapy with AC (unknown). The use of BEIR VII for risk modeling with higher doses of RT needs to be validated.

Anthropogenic disturbance as a driver of microspatial and microhabitat segregation of cytotypes of Centaurea stoebe and cytotype interactions in secondary contact zones.

BACKGROUND AND AIMS: In a mixed-ploidy population, strong frequency-dependent mating will lead to the elimination of the less common cytotype, unless prezygotic barriers enhance assortative mating. However, such barriers favouring cytotype coexistence have only rarely been explored. Here, an assessment is made of the mechanisms involved in formation of mixed-ploidy populations and coexistence of diploid plants and their closely related allotetraploid derivates from the Centaurea stoebe complex (Asteraceae). METHODS: An investigation was made of microspatial and microhabitat distribution, life-history and fitness traits, flowering phenology, genetic relatedness of cytotypes and intercytotype gene flow (cpDNA and microsatellites) in six mixed-ploidy populations in Central Europe. KEY RESULTS: Diploids and tetraploids were genetically differentiated, thus corroborating the secondary origin of contact zones. The cytotypes were spatially segregated at all sites studied, with tetraploids colonizing preferentially drier and open microhabitats created by human-induced disturbances. Conversely, they were rare in more natural microsites and microsites with denser vegetation despite their superior persistence ability (polycarpic life cycle). The seed set of tetraploid plants was strongly influenced by their frequency in mixed-ploidy populations. Triploid hybrids originated from bidirectional hybridizations were extremely rare and almost completely sterile, indicating a strong postzygotic barrier between cytotypes. CONCLUSIONS: The findings suggest that tetraploids are later immigrants into already established diploid populations and that anthropogenic activities creating open niches favouring propagule introductions were the major factor shaping the non-random distribution and habitat segregation of cytotypes at fine spatial scale. Establishment and spread of tetraploids was further facilitated by their superior persistence through the perennial life cycle. The results highlight the importance of non-adaptive spatio-temporal processes in explaining microhabitat and microspatial segregation of cytotypes.

Place de ta vitamine D, du sevelamer et du cinacalcet dans la prise en charge des patients en insuffisance rénale [Treatment of secondary hyperparathyroidism in renal insufficiency: role of calcitriol, sevelamer and cinacalcet]

Along with the decrease in kidney function arises a secondary hyperparathyroidism, which constitutes one of the most important risk factor for mortality in patients suffering from renal insufficiency. Treating secondary hyperparathyroidism is challenging, as most of the parameters of mineral metabolism are interconnected. We review here the pathophysiology and treatment options of this entity.

Addressing trypsin bias in large scale (phospho)proteome analysis by size exclusion chromatography and secondary digestion of large post-trypsin peptides.

In the vast majority of bottom-up proteomics studies, protein digestion is performed using only mammalian trypsin. Although it is clearly the best enzyme available, the sole use of trypsin rarely leads to complete sequence coverage, even for abundant proteins. It is commonly assumed that this is because many tryptic peptides are either too short or too long to be identified by RPLC-MS/MS. We show through in silico analysis that 20-30% of the total sequence of three proteomes (Schizosaccharomyces pombe, Saccharomyces cerevisiae, and Homo sapiens) is expected to be covered by Large post-Trypsin Peptides (LpTPs) with M(r) above 3000 Da. We then established size exclusion chromatography to fractionate complex yeast tryptic digests into pools of peptides based on size. We found that secondary digestion of LpTPs followed by LC-MS/MS analysis leads to a significant increase in identified proteins and a 32-50% relative increase in average sequence coverage compared to trypsin digestion alone. Application of the developed strategy to analyze the phosphoproteomes of S. pombe and of a human cell line identified a significant fraction of novel phosphosites. Overall our data indicate that specific targeting of LpTPs can complement standard bottom-up workflows to reveal a largely neglected portion of the proteome.

Outcome of subscapularis muscle release for shoulder contracture secondary to brachial plexus palsy at birth.

Children with unresolved brachial plexus palsy frequently develop a disabling internal rotation contracture of the shoulder. Several surgical options, including soft tissue procedures such as muscle releases and/or transfers, and bone operations such as humeral osteotomy are available to correct this deformity. This study describes the effect of subscapularis muscle release performed in isolation. Thirteen patients (5 boys, 8 girls) were reviewed at an average of 3.5 years after their surgery (range, 2-7 years). Their mean age at operation was 4.7 years (range, 1-8 years). Three children had C5-C6 palsies, 8 had C5-C7 palsies, and 2 had C5-C8 palsies. Postoperatively, patients presented significant gains in shoulder active lateral rotation (+49 degrees, from 5 to 54 degrees), active abduction (+30 degrees, from 63 to 93 degrees), active flexion (+46 degrees, from 98 to 144 degrees), and active extension (+23 degrees, from 7 to 30 degrees). Gains were also observed in passive range of motion, but of a lesser degree. Subscapularis muscle release is a procedure we found to have few significant complications and was highly effective in increasing active range of motion and restoring shoulder function.

A Sufficiency Rating System for Secondary Roads in Iowa, HR-264, Volume I, 1985

County engineers in Iowa face the dual problems of rapidly escalating costs and a decreasing rate of growth of revenues. Various priority systems are in use, ranking projects for inclusion in road improvement programs, but they generally have weaknesses when used to compare one project with another in a different location. The sufficiency rating system has proven to be a useful tool in developing a priority list of projects for primary road systems, but there are none currently in use for secondary road systems. The research reported here was undertaken to develop a sufficiency rating system which could be used for secondary roads in Iowa and to produce the necessary forms and instructions to aid county engineering personnel in their efforts to complete the ratings for roads within their county.

Small RNA-dependent expression of secondary metabolism is controlled by Krebs cycle function in Pseudomonas fluorescens.

Pseudomonas fluorescens CHA0, an antagonist of phytopathogenic fungi in the rhizosphere of crop plants, elaborates and excretes several secondary metabolites with antibiotic properties. Their synthesis depends on three small RNAs (RsmX, RsmY, and RsmZ), whose expression is positively controlled by the GacS-GacA two-component system at high cell population densities. To find regulatory links between primary and secondary metabolism in P. fluorescens and in the related species Pseudomonas aeruginosa, we searched for null mutations that affected central carbon metabolism as well as the expression of rsmY-gfp and rsmZ-gfp reporter constructs but without slowing down the growth rate in rich media. Mutation in the pycAB genes (for pyruvate carboxylase) led to down-regulation of rsmXYZ and secondary metabolism, whereas mutation in fumA (for a fumarase isoenzyme) resulted in up-regulation of the three small RNAs and secondary metabolism in the absence of detectable nutrient limitation. These effects required the GacS sensor kinase but not the accessory sensors RetS and LadS. An analysis of intracellular metabolites in P. fluorescens revealed a strong positive correlation between small RNA expression and the pools of 2-oxoglutarate, succinate, and fumarate. We conclude that Krebs cycle intermediates (already known to control GacA-dependent virulence factors in P. aeruginosa) exert a critical trigger function in secondary metabolism via the expression of GacA-dependent small RNAs.

Roadway Lighting on Secondary Roads in Iowa, HR-251, 1984

There are approximately 800 installations of destination lighting at secondary road intersections in Iowa. Approximately 90% of these have only a single luminaire. The other installations have two luminaires. No warrants currently exist for justifying the use of this type of lighting. Previous research has examined the safety benefits from full lighting of rural intersections that generally serve substantially higher traffic volumes than secondary road intersections in Iowa. However, the safety benefit of destination lighting at intersections carrying relatively low volumes has not been the subject of previous research. The research reported here, sponsored by the Iowa Department of Transportation, was undertaken to identify locations where destination lighting could be expected to improve highway safety. If destination lighting were shown to reduce accident frequency, warrants for its use on secondary roads could be developed. An inventory of secondary road lighting installations in Iowa was assembled. From this inventory, two samples were constituted that would permit two separate comparisons of the accident experience with and without destination lighting. Before and after comparisons were made for the same locations if accident records were available for at least one full year both preceding and following the installation of destination lighting. Accident records for this purpose were available from a statewide computerized record system covering the period from 1977 through 1982. The accident experience at locations having destination lighting installed before 1978 was compared with a sample of comparable locations not having destination lighting. The sample of secondary road intersections used for the before and after comparison included 91 locations. The sample of continuously lighted locations included 102 intersections. Accident experience at these locations was compared with the experience at 102 intersections that were not lighted. The intersections included in these samples averaged only 0.31 accidents per year. The accident rate at secondary road intersections that had destination lighting did not differ significantly from the accident rate at intersections that were not lighted. This conclusion was derived from both comparisons, the before and after experience and the comparison of experience at intersections that were continuously lighted with that at unlighted locations. Furthermore, no significant differences were noted between lighted and unlighted locations in the proportion of accidents that occurred at night. The distribution of accidents by type also did not differ between unlighted intersections and those having destination lighting. It was not possible to formulate warrants for destination lighting since analyses directed toward identifying specific characteristics of an intersection that could be correlated with highway safety did not yield any useful relationships. However, it was noted that the average damages for night accidents that occurred at lighted intersections were lower than for accidents at unlighted intersections. Even in the absence of a more definitive demonstration of beneficial effects, destination lighting is perceived by officials in most of the counties having such installations as yielding desirable effects and is recognized as helpful to motorists in performing the guidance function in driving. Given this benefit and a relatively low cost (an average of $74 per year for one luminaire), and given that the subjective criteria that have been used in the past to justify the installation of destination lighting have led to a high degree of public acceptance and satisfaction, it is recommended that the same subjective criteria continue to be used in lieu of definitive warrants.

A Sufficiency Rating System for Secondary Roads in Iowa, HR-264, Volume II, 1985

The goal of this study is to develop a usable sufficiency rating system for secondary roads. There are several assumptions that have been made at the outset. These are: 1. County engineers currently use at least a limited set of decision criteria to make decisions regarding project priorities. 2. Some degree of consensus exists among the county engineers in terms of which are the most important criteria and that there is some agreement on their relative importance. Accordingly, a questionnaire was developed which could be used as a survey tool. The results of the survey were used to develop a final list of weighted rating elements which were used as part of the proposed sufficiency rating system. State and local jurisdictions from other states were also surveyed to determine the status of the use of sufficiency rating systems for secondary roads outside of Iowa and to gather some applicable data.

Snow Removal on Iowa's Secondary Roads, HR-267, 1984

Snow removal on the 90,000 mile Iowa secondary road system is a major concern of county engineers. Rural residents rely almost entirely on motor vehicles for travel. They have come to expect passable roads during all types of weather and as most county engineers know, the public is less tolerant of problems in snow removal than in any other highway department function. To avoid snow removal problems, maintenance personnel begin preparation before the winter maintenance season. The slide tape presentation, "Snow Removal on Iowa's Secondary Roads", was developed to assist in training and retraining maintenance personnel each year prior to winter. The program covers preparation for winter, snow and ice removal, and after storm care of equipment.

Secondary prevention of osteoporotic fractures : room for improvement

Résumé : Introduction : l'ostéoporose est une maladie fréquente, invalidante, sous-diagnostiquée et sous-traitée, alors qu'il existe des évidences cliniques, densitométriques et biologiques de l'efficacité de la prévention secondaire. Matériel et méthode : dans cette étude, nous décrivons les habitudes de prescription de traitements en prévention secondaire dans les 6 mois qui suivent une fracture de fragilité et définissons les catégories de femmes recevant ou non un traitement, selon le type de fractures, les antécédents fracturaires et les données socio-démographiques. Il s'agit d'une étude suisse de cohorte, prospective de 7609 femmes de 70 ans et plus, suivies de 1998 à 2000. Deux groupes de patientes ont été analysés : celles avec un événement fracturaire durant le suivi (3 sous-groupes de fractures ont été considérés fractures vertébrales, fractures du radius distal et fractures de l'humérus proximal) et celles sans fractures durant le suivi (groupe contrôle). La détermination des événements fracturaires et l'instauration d'un traitement s'est faite par l'envoi aux patientes et à leurs médecins traitants d'un questionnaire structuré. Dans cette étude, le but primaire est de décrire les attitudes médicales de prévention secondaire, le but secondaire d'analyser les motifs dé décision thérapeutique (type de fracture, antécédents de fractures), alors que le but tertiaire cherche à caractériser les femmes non traitées. Résultats, discussion : 7354 femmes ont été incluses dans cette étude, 183 dans le groupe fracture et 7171 dans le groupe contrôle. Le suivi moyen a été de 21 mois. L'introduction d'un traitement est restée rare dans chaque catégorie de fracture et a été plus importante pour le sous-groupe avec fracture vertébrale (p<0.001). La seule donnée associée à l'adjonction d'un traitement a été la présence d'un antécédent anamnestique de fracture vertébrale. La description des attitudes thérapeutiques après une fracture de fragilité, a montré que. 44 % des femmes ne reçoivent aucun traitement en prévention secondaire. Seule la fracture vertébrale et les antécédents de fracture vertébrale entraînent une modification de l'attitude thérapeutique des médecins traitants mais de façon encore insuffisante puisque plus de 50 % des femmes avec une fracture de vertèbre n'ont aucun changement dans leur prise en charge. Les femmes non traitées ne différaient pas des autres sur un plan socio-démographique. Le nombre de patientes dans chaque sous-groupe est relativement faible ce qui limite !a puissance statistique de l'analyse. Les données consistent essentiellement en du « selfreporting » ce qui peut limiter la signification de celles-ci. Les résultats sont cependant suffisamment inquiétants pour que de nouvelles campagnes d'information soient lancées auprès des médecins de .premiers recours quant à la nécessité d'instaurer un traitement efficace lors de la survenue d'une fracture clinique ou radiologique chez une femme en post-ménopause.

Maintaining Iowa's Secondary Road Environment, HR-289, 1989

The Iowa counties have been successful in maintaining a good roadway environment on our 90,000 mile secondary road system. However, county highway personnel must remain vigilant in detecting, discovering and correcting potential problems if our roads are to remain so. This presentation was developed for those county personnel who work and travel on secondary roads. The presentation discusses things county personnel can look for during their daily operations which could possibly create a potential problem. If these situations are uncovered and corrected in a timely manner, our secondary road system will be maintained in an appropriate manner.

Expressed isolated integrin beta1 subunit cytodomain induces endothelial cell death secondary to detachment.

Expression of isolated beta integrin cytoplasmic domains in cultured endothelial cells was reported to induce cell detachment and death. To test whether cell death was the cause or the consequence of cell detachment, we expressed isolated integrin beta1 cytoplasmic and transmembrane domains (CH1) in cultured human umbilical vein endothelial cells (HUVEC), and monitored detachment, viability, caspase activation and signaling. CH1 expression induced dose-dependent cell detachment. At 24 h over 90% of CH1-expressing HUVEC were detached but largely viable (>85%). No evidence of pro-caspase-8,-3, and PARP cleavage or suppression of phosphorylation of ERK, PKB and Ikappa-B was observed. The caspase inhibitor z-VAD did not prevent cell detachment. At 48 h, however, CH1-expressing cells were over 50% dead. As a comparison trypsin-mediated detachment resulted in a time-dependent cell death, paralleled by caspase-3 activation and suppression of ERK, PKB and Ikappa-B phosphoyrylation at 24 h or later after detachment. HUVEC stimulation with agents that strengthen integrin-mediated adhesion (i.e. PMA, the Src inhibitor PP2 and COMP-Ang1) did not prevent CH1-induced detachment. Expression of CH1 in rat carotid artery endothelial cells in vivo caused endothelial cell detachment and increased nuclear DNA fragmentation among detached cells. A construct lacking the integrin cytoplasmic domain (CH2) had no effect on adhesion and cell viability in vitro and in vivo. These results demonstrate that isolated beta1 cytoplasmic domain expression induces caspase-independent detachment of viable endothelial cells and that death is secondary to detachment (i.e. anoikis). They also reveal an essential role for integrins in the adhesion and survival of quiescent endothelial cells in vivo.