On the consistency of seismically imaged lower mantle slabs.

The geoscience community is increasingly utilizing seismic tomography to interpret mantle heterogeneity and its links to past tectonic and geodynamic processes. To assess the robustness and distribution of positive seismic anomalies, inferred as subducted slabs, we create a set of vote maps for the lower mantle with 14 global P-wave or S-wave tomography models. Based on a depth-dependent threshold metric, an average of 20% of any given tomography model depth is identified as a potential slab. However, upon combining the 14 models, the most consistent positive wavespeed features are identified by an increasing vote count. An overall peak in the most robust anomalies is found between 1000-1400 km depth, followed by a decline to a minimum around 2000 km. While this trend could reflect reduced tomographic resolution in the middle mantle, we show that it may alternatively relate to real changes in the time-dependent subduction flux and/or a mid-lower mantle viscosity increase. An apparent secondary peak in agreement below 2500 km depth may reflect the degree-two lower mantle slow seismic structures. Vote maps illustrate the potential shortcomings of using a limited number or type of tomography models and slab threshold criteria.

Human myiasis in western Jamaica: five years after the implementation of a screwworm eradication programme

OBJECTIVE: To determine the distribution of cases of human myiasis admitted to the Cornwall Regional Hospital (CRH), Jamaica, between 1999 and 2003, following the inception of the National Screwworm Eradication Programme (NSEP) in 1998, and the risk factors associated with the condition. METHOD: A total of 144 cases of myiasis were retrieved from the database of the department of Medical Records at the CRH for the years 1999 to 2003. A data extraction form was devised to review the circumstances of each case. The data were analyzed using EpiInfo version 6. RESULTS: Of 144 cases, 54.9% were female and 45.1% male. The largest groups were < 10 years, 52.8% [76/144 (M-21, F-55)] and 60years and over, 18.8% [27/144 (M-16, F-I)] (p < 0.001). Case distribution for the years 1999-2003 showed 16, 39, 31, 30, and 28 cases respectively. Three-quarters (74.6%) of all cases affected the scalp/head one-fifth (20.3%) affected the lower limbs. Ninety-six per cent of those < 10 years had scalp/head myiasis (p < 0.001; OR = 23.29; CI: 6.14 < OR < 104.11). Two-thirds (66.6%) of those 60 years and over had lower limb myiasis (p < 0.001; OR = 19.09; CI: 6.20 < OR < 61.12). Mean duration of treatment was 3.5 days (SD = 1.4 days) and 69.7% required hospitalization for seven or more days. There was no difference in duration of treatment for myiasis or in length of hospitalization in relation to method used to eliminate maggots. Risk factors identified included Tinea capitis for myiasis of the scalp/head (p < 0.001) and diabetes mellitus for lower limb myiasis (p < 0.001; OR = 14.48; CI: 2.37 < OR < 133.25). CONCLUSION: Human myiasis remains a public health issue in western Jamaica with no significant decreasing trend in the number of cases admitted to the CRH since 1999. It is recommended that this zoonosis become a Class 1 notifiable disease to the Ministries of Health and Agriculture because of the existing NSEP.

Human myiasis in western Jamaica: five years after the implementation of a screwworm eradication programme.

OBJECTIVE: To determine the distribution of cases of human myiasis admitted to the Cornwall Regional Hospital (CRH), Jamaica, between 1999 and 2003, following the inception of the National Screwworm Eradication Programme (NSEP) in 1998, and the risk factors associated with the condition. METHOD: A total of 144 cases of myiasis were retrieved from the database of the department of Medical Records at the CRH for the years 1999 to 2003. A data extraction form was devised to review the circumstances of each case. The data were analyzed using EpiInfo version 6. RESULTS: Of 144 cases, 54.9% were female and 45.1% male. The largest groups were < 10 years, 52.8% [76/144 (M-21, F-55)] and 60years and over, 18.8% [27/144 (M-16, F-I)] (p < 0.001). Case distribution for the years 1999-2003 showed 16, 39, 31, 30, and 28 cases respectively. Three-quarters (74.6%) of all cases affected the scalp/head one-fifth (20.3%) affected the lower limbs. Ninety-six per cent of those < 10 years had scalp/head myiasis (p < 0.001; OR = 23.29; CI: 6.14 < OR < 104.11). Two-thirds (66.6%) of those 60 years and over had lower limb myiasis (p < 0.001; OR = 19.09; CI: 6.20 < OR < 61.12). Mean duration of treatment was 3.5 days (SD = 1.4 days) and 69.7% required hospitalization for seven or more days. There was no difference in duration of treatment for myiasis or in length of hospitalization in relation to method used to eliminate maggots. Risk factors identified included Tinea capitis for myiasis of the scalp/head (p < 0.001) and diabetes mellitus for lower limb myiasis (p < 0.001; OR = 14.48; CI: 2.37 < OR < 133.25). CONCLUSION: Human myiasis remains a public health issue in western Jamaica with no significant decreasing trend in the number of cases admitted to the CRH since 1999. It is recommended that this zoonosis become a Class 1 notifiable disease to the Ministries of Health and Agriculture because of the existing NSEP.

Xyloglucan endotransglycosylase, a new wall-loosening enzyme activity from plants.

1. Cell-free extracts of all plants tested contained a novel enzyme activity (xyloglucan endotransglycosylase, XET) able to transfer a high-Mr portion from a donor xyloglucan to a suitable acceptor such as a xyloglucan-derived nonasaccharide (Glc4Xyl3GalFuc; XG9). 2. A simple assay for the enzyme, using [3H]XG9 and based on the ability of the [3H]polysaccharide product to bind to filter paper, is described. 3. The enzyme was highly specific for xyloglucan as the glycosyl donor, and showed negligible transglycosylation of other polysaccharides, including CM-cellulose. 4. The Km for XG9 was 50 microM; certain other 3H-labelled xyloglucan oligosaccharides also acted as acceptors, and certain non-radioactive xyloglucan oligosaccharides competed with [3H]XG9 as acceptor; the minimum acceptor structure was deduced to be: [formula: see text] 5. The pH optimum was approx. 5.5 and the enzyme was less than half as active at pH 7.0. The enzyme was slightly activated by Ca2+, Mg2+, Mn2+, spermidine, ascorbate and 2-mercaptoethanol, and inhibited by Ag+, Hg2+, Zn2+ and La3+. 6. XET activity was essentially completely extracted by aqueous solutions of low ionic strength; Triton X-100, Ca2+, La3+, and Li+ did not enhance extraction. Negligible activity was left in the unextractable (cell-wall-rich) residue. 7. The enzyme differed from the major cellulases (EC 3.2.1.4) of pea in: (a) susceptibility to inhibition by cello-oligosaccharides, (b) polysaccharide substrate specificity, (c) inducibility by auxin, (d) requirement for salt in the extraction buffer and (e) activation by 2-mercaptoethanol. XET is therefore concluded to be a new enzyme activity (xyloglucan: xyloglucan xyloglucanotransferase; EC 2.4.1.-). 8. XET was detected in extracts of the growing portions of dicotyledons, monocotyledons (graminaceous and liliaceous) and bryophytes. 9. The activity was positively correlated with growth rate in different zones of the pea stem. 10. We propose that XET is responsible for cutting and rejoining intermicrofibrillar xyloglucan chains and that it thus causes the wall-loosening required for plant cell expansion.