Diagnostic accuracy of paediatric echocardiograms interpreted by individuals other than paediatric cardiologists

Objective: To assess the diagnostic error rate among echocardiograms undertaken by individuals other than paediatric cardiologists in our referral area. Methodology: External group: The charts and echocardiographic results of all patients who had undergone outside echocardiograms between January 1996 and December 1999 were reviewed (110). Age at echocardiography, diagnostic complexity, presence of any diagnostic errors and the severity of any diagnostic errors were identified. Internal group: To assess our own error rate, the initial echocardiographic diagnoses of 100 patients undergoing cardiac catheterisation or corrective surgery were compared with the post-catheterisation or postoperative diagnoses. Age and diagnostic complexity were also assessed in the control group. Results: Diagnostic errors occurred in 47/110 patients (44%) of the externally studied group (of which 24% were either major or life threatening) as opposed to 3/100 of the internally studied group, despite the internally studied group being of increased diagnostic complexity. Errors were more common and of increased severity in infants less than 1 month of age but extended throughout all age groups. Major and life threatening errors increased with increasing diagnostic complexity. In the externally studied group, 8/47 errors were patients inappropriately designated as normal. Four of these patients required cardiac surgery or interventional cardiac catheterisation. Conclusions: This study suggests an unacceptably high error rate in paediatric echocardiographic diagnoses by non-paediatric cardiologists throughout all age groups. Such errors are more likely in younger infants and with increasing diagnostic complexity.

Efficacy of praziquantel against Schistosoma japonicum: field evaluation in an area with repeated chemotherapy compared with a newly identified endemic focus in Hunan, China

This study conducted in 1999/2000 was designed to evaluate the efficacy of praziquantel against Schistosoma japonicum in an area with repeated chemotherapy (Area A) compared with a newly identified endemic focus (Area B) in Hunan Province, China. The population size was 2015 and 2180 in Areas A and B, respectively, of which 1129 and 1298 subjects received stool examination. A total of 230 subjects were identified by the Kato-Katz technique (4 smears per person) as being infected with S. japonicum, 124 in Area A (prevalence 11 %) and 106 in Area B (prevalence 8.2%). They were treated with a single oral dose of praziquantel (40 mg/kg) in the non-transmission season. A follow-up stool examination was made 50 days after treatment. Among the 220 cases followed, 22 were found stool-egg-positive, with an overall cure rate of 90 %, and 99 % reduction of infection intensity (eggs per gram stool). No significant difference was found in cure rates between the 2 areas (89.7% vs 90.3%). The efficacy of the drug in the area with repeated chemotherapy was not significantly different from that in the newly identified endemic focus. This study, therefore, suggests that the efficacy of praziquantel against S. japonicum has not changed in the Dongting Lake region after more than 14 years of mass chemotherapy, and there is no evidence of tolerance or resistance of S. japonicum against praziquantel.

Larval hosts of Australian Drosophilidae (Diptera): A field survey in subtropical and tropical Australia

The drosophilid fauna in Australia offers an important study system for evolutionary studies. Larval hosts are unknown for most species, however, and this imposes serious limits to understanding their ecological context. The present paper reports the first systematic, large-scale field survey of potential larval hosts to be conducted, in order to obtain an overview of the host utilisation patterns of Australian drosophilids. Potential hosts (mostly fruit and fungi) were collected from different vegetation types in northern and eastern Australia. Host data were obtained for 81 drosophilid species from 17 genera (or 28% of the known Fauna). Most genera were restricted to either fruit or fungi, although Scaptodrosophila spp. and Drosophila spp. were recorded from fruit, fungi, flowers and compost, and Drosophila spp. also emerged from the parasitic plant Balanophora fungosa. There was no evidence that use of either fruit or fungi was correlated to host phylogeny. Drosophilids emerged from hosts collected from all sampled vegetation types (rainforest, open forest, heath and domestic environments). Vegetation type influenced drosophilid diversity, both by affecting host availability and because some drosophilid species apparently restricted their search for hosts to particular vegetation types.

The first strand transfer reaction of HIV-1 reverse transcription is more efficient in infected cells than in cell-free natural endogenous reverse transcription reactions

Background: In the presence of dNTPs, intact HIV-1 virions are capable of reverse transcribing at least part of their genome, a process known as natural endogenous reverse transcription (NERT). PCR analysis of virion DNA produced by NERT revealed that the first strand transfer reaction (1stST) was inefficient in intact virions, with minus strand (-) strong stop DNA (ssDNA) copy numbers up to 200 times higher than post-1stST products measured using primers in U3 and U5. This was in marked contrast to the efficiency of 1stST observed in single-round cell infection assays, in which (-) ssDNA and U3-U5 copy numbers were indistinguishable. Objectives: To investigate the reasons for the discrepancy in first strand transfer efficiency between intact cell-free virus and the infection process. Study design: Alterations of both NERT reactions and the conditions of cell infection were used to test whether uncoating and/or entry play a role in the discrepancy in first strand transfer efficiency. Results and Conclusions: The difference in 1stST efficiency could not be attributed simply to viral uncoating, since addition of very low concentrations of detergent to NERT reactions removed the viral envelope without disrupting the reverse transcription complex, and these conditions resulted in no improvement in 1stST efficiency. Virus pseudotyped with surface glycoproteins from either vesicular stomatitis virus or amphotrophic murine leukaemia virus also showed low levels of 1stST in low detergent NERT assays and equivalent levels of (-) ssDNA and 1stST in single-round infections of cells, demonstrating that the gp120-mediated infection process did not select for virions capable of carrying out 1stST. These data indicate that a post-entry event or factor may be involved in efficient HIV-1 reverse transcription in vivo. (C) 2002 Elsevier Science B.V. All rights reserved.

On the induced electric field gradients in the human body for magnetic stimulation by gradient coils in MRI

Prior theoretical studies indicate that the negative spatial derivative of the electric field induced by magnetic stimulation may he one of the main factors contributing to depolarization of the nerve fiber. This paper studies this parameter for peripheral nerve stimulation (PNS) induced by time.-varying gradient fields during MRI scans. The numerical calculations are based on an efficient, quasi-static, finite-difference scheme and an anatomically realistic human, full-body model. Whole-body cylindrical and planar gradient sets in MRI systems and various input signals have been explored. The spatial distributions of the induced electric field and their gradients are calculated and attempts are made to correlate these areas with reported experimental stimulation data. The induced electrical field pattern is similar for both the planar coils and cylindrical coils. This study provides some insight into the spatial characteristics of the induced field gradients for PNS in MRI, which may be used to further evaluate the sites where magnetic stimulation is likely to occur and to optimize gradient coil design.

Intracellular compartmentation in planctomycetes

The phylum Planctomycetes of the domain Bacteria consists of budding, peptidoglycan-less organisms important for understanding the origins of complex cell organization. Their significance for cell biology lies in their possession of intracellular membrane compartmentation. All planctomycetes share a unique cell plan, in which the cell cytoplasm is divided into compartments by one or more membranes, including a major cell compartment containing the nucleoid. Of special significance is Gemmata obscuriglobus, in which the nucleoid is enveloped in two membranes to form a nuclear body that is analogous to the structure of a eukaryotic nucleus. Planctomycete compartmentation may have functional physiological roles, as in the case of anaerobic ammonium-oxidizing anammox planctomycetes, in which the anammoxosome harbors specialized enzymes and is wrapped in an envelope possessing unique ladderane lipids. Organisms in phyla other than the phylum Planctomycetes may possess compartmentation similar to that of some planctomycetes, as in the case of members of the phylum Poribacteria from marine sponges.