Neglected role of fungal community composition in explaining variation in wood decay rates.

Decomposition of wood is an important component of global carbon cycling. Most wood decomposition models are based on tree characteristics and environmental conditions; however, they do not include community dynamics of fungi that are the major wood decomposers. We examined the factors explaining variation in sapwood decay in oak tree stumps two and five years after cutting. Wood moisture content was significantly correlated with sapwood decay in younger stumps, whereas ITS-based composition and species richness of the fungal community were the best predictors for mass loss in the older stumps. Co-occurrence analysis showed that, in freshly cut trees and in younger stumps, fungal communities were nonrandomly structured, whereas fungal communities in old stumps could not be separated from a randomly assembled community. These results indicate that the most important factors explaining variation in wood decay rates can change over time and that the strength of competitive interactions between fungi in decaying tree stumps may level off with increased wood decay. Our field analysis further suggests that ascomycetes may have a prominent role in wood decay, but their wood-degrading abilities need to be further tested under controlled conditions. The next challenging step will be to integrate fungal community assembly processes in wood decay models to improve carbon sequestration estimates of forests.

Patterns of fungal communities among and within decaying logs, revealed by 454 sequencing.

Owing to previous methodological limitations, knowledge about the fine-scale distribution of fungal mycelia in decaying logs is limited. We investigated fungal communities in decaying Norway spruce logs at various spatial scales at two environmentally different locations in Sweden. On the basis of 454 pyrosequencing of the ITS2 region of rDNA, 1914 operational taxonomic units (OTUs) were detected in 353 samples. The communities differed significantly among logs, but the physical distance between logs was not found to have a significant effect on whether fungal communities had any resemblance to each other. Within a log, samples that were closer together generally had communities that showed more resemblance to each other than those that were further apart. OTUs characteristic for particular positions on the logs could be identified. In general, these OTUs did not overlap with the most abundant OTUs, and their ecological role was often unknown. Only a few OTUs were detected in the majority of logs, whereas numerous OTUs were rare and present in only one or a few logs. Wood-decaying Basidiomycetes were often represented by higher sequence reads in individual logs than Ascomycete OTUs, suggesting that Basidiomycete mycelia spread out more rapidly when established. OTU richness tended to increase with the decay stage of the sample; however, the known wood decayers were most abundant in less-decomposed samples. The fungi identified in the logs represented different ecological strategies. Our findings differ from previously published sporocarp studies, indicating that the highly abundant fruiting species may respond to environment in different ways than the rest of the fungal community.

Subjective and objective symptoms in relation to plasma methadone concentration in methadone patients.

Two rating scales, which were originally developed for measurements of objective and subjective signs of opiate withdrawal, were used to evaluate potential estimates (correlates) of methadone effects in relation to plasma methadone concentrations. Patients participating in our regular methadone maintenance treatment project were studied during 24 h after the intake of the daily methadone dose. Methadone concentrations in plasma were compared to the subjective (estimated by the patients) and objective (estimated by the investigator) signs of the drug effects before, and 2.5, 5, 9 and 24 h after intake of methadone. Some new items possibly related to rising methadone concentrations were added to the subjective scale. Results indicated that, for subjective ratings, the majority of the items investigated corresponded well with the plasma methadone concentrations. The most significant associations were found for the following items: low psychomotor speed, alertness, running nose, yawning and anxiety. For objective ratings, only the items rhinorrhea, piloerection and signs of anxiety were significantly associated with the methadone concentrations. These rating scales may, together with plasma methadone determinations, be of considerable value when making dose adjustments for methadone maintenance patients. Further work is, however, needed to establish concentration-effect relationships.

Imipenem/cilastatin versus gentamicin/clindamycin: a cost effectiveness study.

A previously published clinical trial was used for analysis of costs for antibiotic treatment in patients with serious bacterial infections requiring the use of injectable broad spectrum antibiotics. The patients were randomized to receive imipenem/cilastatin 500/500 mg q6h (77 patients of which 56 were evaluable for efficacy) or clindamycin 600 mg q6h plus gentamicin 1.5 mg/kg with dose intervals determined by serum concentration monitoring (86 patients of which 62 were evaluable for efficacy). An analysis of the costs for antibiotics, including drugs, equipment and staff for administration and gentamicin serum concentration assays, showed that imipenem/cilastatin was not more expensive than gentamicin plus clindamycin per treatment day although the drug cost was considerably higher for imipenem/cilastatin. Since imipenem/cilastatin was significantly more effective and caused less frequent adverse reactions than gentamicin plus clindamycin it was more cost-effective in the patients studied.

Accuracy at radiography and probing for the diagnosis of proximal caries.

In 63 teenagers the proximal surfaces of premolars to be extracted for orthodontic reasons and the adjacent surfaces of neighboring teeth, 598 surfaces in all, were examined radiographically and by probing. Direct inspection after extraction revealed that 51% of the surfaces had incipient carious lesions and 5% lesions with cavities. Of the surfaces with cavities 82.1% were correctly diagnosed radiographically if any radiolucency, regardless of its extent, was used as a diagnostic criterion. However, this yielded a false positive rate of 19.6%. If only radiolucencies extending at least into the inner third of the enamel were called positive the true positive rate was 36.7% and the associated false positive rate 1.6%. At a 5% cavity frequency the predictive positive values were 17% and 53%, respectively. Probing yielded a true positive rate of about 29% and a false positive rate of 1.1% with a predictive positive value of 50-57%. All radiolucencies extending into the dentin were associated with cavities. When the most liberal radiographic criterion was used 37.5% of all carious lesions, whether associated with a cavity or not, were detected and 3.8% of sound surfaces were falsely called carious. The corresponding predictive positive value at the actual rate of incipient lesions and lesions with cavities was 92.6%.