Landscape-level validation of allometric relationships for carbon stock estimation reveals bias driven by soil type.

Mitigation of climate change depends on accurate estimation and mapping of terrestrial carbon stocks, particularly in carbon dense tropical forests. Allometric equations can be used to robustly estimate biomass of tropical trees, but often require tree height, which is frequently unknown. Researchers and practitioners must, therefore, decide whether to directly measure a subset of tree heights to develop diameter : height (D:H) equations or rely on previously published generic equations. To date, studies comparing the two approaches have been spatially restricted and/or not randomly allocated across the landscape of interest, making the implications of deciding whether or not to measure tree heights difficult to determine. To address this issue, we use inventory data from a systematic-random forest inventory across Gabon (102 forest sites; 42,627 trees, including 7,036 height-measured trees). Using plot-specific models of D:H as a benchmark, we compare the performance of a suite of locally fitted and commonly used generic models (parameterized national, georegional, and pantropical equations) across a variety of scales, and assess which abiotic, anthropogenic, and topographical covariates contribute the most to bias in height estimation. We reveal marked spatial structure in the magnitude and direction of bias in tree height estimation using all generic models, due at least in part to soil type, which compounded to substantial error in site-level AGB estimates (of up to 38% or 150 Mg/ha). However, two generic pantropical models (Chave 2014; Feldpausch 2012) converged to within 2.5% of mean AGB at the landscape scale. Our results suggest that some (not all) pantropical equations can extrapolate AGB across large spatial scales with minimal bias in estimated mean AGB. However, extreme caution must be taken when interpreting the AGB estimates from generic models at the site-level as they fail to capture substantial spatial variation in D:H relationships, which could lead to dramatic under- or over-estimation of site-level carbon stocks. Validated allometric models derived at site- or soil-type-levels may be the best way to reduce such biases arising from landscape-level heterogeneity in D:H model fit in the Afrotropics.

Diagnosis and management of common maxillofacial injuries in the emergency department. Part 5: Dentoalveolar injuries.

Injuries to teeth can be very distressing for patients. Prompt treatment is essential. Injuries of the tooth bearing portion of the mandible are common and can even result after a relatively low impact trauma. The alveolus (tooth bearing portion of bone) and/or the tooth may be damaged. Segmental fractures involve multiple teeth and the supporting alveolar bone.

Diagnosis and management of common maxillofacial injuries in the emergency department. Part 4: orbital floor and midface fractures.

Beware of the black eye! Orbital injuries are often missed or misdiagnosed. The underlying bony injury and or globe injury are often more serious than initial examination suggests.

Diagnosis and management of common maxillofacial injuries in the emergency department. Part 2: mandibular fractures.

The majority of mandibular fractures occur in young males aged 16-30 years. As with all traumas, the history and examination cannot be over emphasised as diagnoses can be made with these tools. It is important when taking an accurate history to ascertain the mode and mechanism of injury (fall, punch, road traffic accident), and the magnitude and direction of the force involved (high or low velocity impact).

Diagnosis and management of common maxillofacial injuries in the emergency department. Part 1: Advanced trauma life support.

Maxillofacial injuries are often seen in the emergency department. Fractures of the facial skeleton are commonly seen after assault, road traffic accidents, falls, and sporting injuries in a ratio mandibular:zygoma:maxillary of 6:2:1. Clinicians must be familiar with their management so that appropriate treatment may be used.

Etiology of zygomatic fractures.

We report on the etiology of zygomatic fractures in an Irish population. More than half of these injuries are related to interpersonal assault. Treatment of these injuries places a considerable burden on the health service.

Both IgM and IgG anti-VSG antibodies initiate a cycle of aggregation-disaggregation of bloodstream forms of Trypanosoma brucei without damage to the parasite.

Bloodstream forms of Trypanosoma brucei, when aggregated in the presence of either acute immune plasma, acute immune serum, purified IgM anti-VSG antibodies or purified IgG anti-VSG antibodies, subsequently disaggregated with a t1/2 for disaggregation of 15 min at 37 degrees C as long as the trypanosomes were metabolically active at the beginning of the experiment and maintained during the experiment in a suitable supporting medium. The t1/2 for disaggregation was found to be directly dependent upon temperature and inversely proportional to the antibody concentration. The trypanosomes were always motile and metabolically active during aggregation and after disaggregation and were fully infective for a mammalian host following disaggregation as well as able to grow and divide normally during axenic culture. The disaggregation was strictly energy dependent and was inhibited when intracellular ATP levels were reduced by salicylhydroxamic acid or following addition of oligomycin while respiring glucose. In addition the process of disaggregation was dependent upon normal endosomal activity as evidenced by its sensitivity to a wide variety of inhibitors of various endosomal functions. Disaggregation was not due to separation of immunoglobulin chains by either disulphide reduction or disulphide exchange reactions and gross proteolytic cleavage of the immunoglobulins attached to the surface of the parasite was not detected. In addition, gross cleavage or release of the VSG from the surface of the cell did not occur during disaggregation but proteolytic cleavage of a small proportion of either the VSG or the immunoglobulins could not be eliminated from consideration. Finally the mechanism of disaggregation was found to be a regulated process, independent of Ca2+ movements but dependent upon the activity of protein kinase C or related kinases and inhibited by the activity of protein kinase A as evidenced by the effects of a panel of inhibitors and cAMP analogues on the process of disaggregation. The mechanism of disaggregation displayed by trypanosomes aggregated by anti-VSG antibody is proposed to form part of the parasite's defence against the host immune system and functions to aid survival of trypanosomes in the presence of antibody in the host prior to the occurrence of a VSG switching event.

Somatic APC and K-ras codon 12 mutations in periampullary adenomas and carcinomas from familial adenomatous polyposis patients.

Periampullary adenomas in the duodenum of Familial Adenomatous Polyposis (FAP) patients are among the most frequent and clinically important extracolonic neoplasms in FAP. The purpose of this study was to characterize the frequency and nature of somatic adenomatous polyposis coli (APC) gene and K-ras codon 12 mutations in periampullary adenomas and carcinomas in FAP. These molecular changes have been shown to be important during the early stages of colorectal carcinogenesis. DNA was prepared from endoscopic periampullary biopsies and paraffin blocks from 49 FAP patients. Of 143 samples, 77 were histologically normal, 29 were biopsies from small periampullary adenomas, 29 biopsies were from 19 large adenomas and eight samples were from periampullary cancers. APC mutations in the mutation cluster region and K-ras codon 12 mutations were detected by polymerase chain reaction based techniques. Somatic APC mutations consisting of deletions at codons 1464 and 1465 were detected in one small and two large periampullary adenomas. Loss of heterozygosity was seen in one periampullary carcinoma. K-ras codon 12 mutations were detected in seven of 19 large periampullary adenomas and in one of eight periampullary carcinomas. These data suggest that K-ras codon 12 mutations may be important during periampullary tumorigenesis in FAP but somatic APC mutations in the mutation cluster region are infrequent. Local environmental factors in the duodenum may contribute to differences in the molecular changes which occur during the adenoma-to-carcinoma sequence in periampullary compared to colonic tumorigenesis.