New stand magnifiers do not meet rated levels of performance

A new range of stand magnifiers has been released by the COIL company in the United Kingdom. Examination of these magnifiers reveals that they fail to deliver the rated magnifications labelled prominently on the appliances, as a result of the manufacturer's conformance with the requirements of the German DIN standard and the use of back vertex power (F'_v) rather than equivalent dioptric power (F_m) of the magnifier. In this study we provide information on the optometric parameters of these new stand magnifiers that will assist the more accurate specification of improvements in vision expected from their use.     

Exclusion of first-episode deep-vein thrombosis after-hours using D-dimer.

The objective of this study was to test the safety of withholding anticoagulant treatment and additional call-back diagnostic testing with ultrasound in patients who have a negative D-dimer at presentation. Patients with signs and symptoms of deep-vein thrombosis who presented to the emergency department after regular hours and on weekends underwent D-dimer testing using the STA-Liatest D-di. In patients with negative D-dimer results, heparin therapy was withheld, and no further diagnostic testing for deep-vein thrombosis was done as part of the initial evaluation. Patients with positive D-dimer results underwent compression ultrasonography. The primary outcome measure was a diagnosis of new symptomatic venous thromboembolism confirmed by diagnostic testing during the 3-month follow-up period. Of the 260 eligible patients, 81 (31%) had a negative D-dimer and 179 (69%) had a positive D-dimer. No patient with a negative D-dimer at presentation had confirmed venous thromboembolism at 3-month follow-up. Three patients died: one by intracranial hemorrhage secondary to cerebrovascular accident; and two deaths of indeterminate cause almost 3 months after entry. The automated assay for D-dimer, the STA-Liatest D-di, seems to provide a simple method with high clinical utility for excluding acute first-episode deep-vein thrombosis in symptomatic patients who present to the emergency room after regular hours.     

Pheochromocytoma and paraganglioma: comparison of MR imaging with CT and I-131 MIBG scintigraphy

To ascertain the magnetic resonance (MR) imaging characteristics of pheochromocytomas and paragangliomas and to compare MR with computed tomography (CT) and iodine-131 metaiodobenzylguanidine (I-131 MIBG), 19 patients (18 with pheochromocytomas, one with a paraganglioma) were studied. The 18 patients with pheochromocytomas had had positive findings with I-131 MIBG scintigraphy. Abdominal pheochromocytomas were generally hypointense compared with normal liver on T1-weighted MR images and extremely hyperintense on T2-weighted MR images. MR imaging was preferable to CT in the evaluation of primary pheochromocytomas due to superior tissue characterization, particularly in the patient with hypertension and borderline catecholamine levels. For patients with recurrent or metastatic disease, the data suggest that I-131 MIBG scintigraphy is the examination of choice.     

Chaperonin-mediated assembly of wild-type and mutant subunits of human propionyl-CoA carboxylase expressed in Escherichia coli

We developed a bacterial expression system for the human alpha and beta cDNAs of propionyl-CoA carboxylase (PCC). These cDNAs (less the putative mitochondrial matrix targeting presequences) were co-expressed in Escherichia coli on one plasmid vector with each cDNA having its own IPTG-inducible promoter. Only negligible amounts of active PCC were measured despite the presence of both alpha and beta subunits as indicated by Western blot analysis and the almost complete biotinylation of the alpha subunit. Co-expression of this plasmid with a second plasmid vector over-expressing the E. coli chaperonin proteins, groES and groEL, resulted in a several hundred-fold increase in PCC specific activity, to a level comparable with that found in crude human liver extracts. PCC was partially purified on monomeric avidin affinity resin and the presence of both alpha and beta subunits was demonstrated, thereby confirming the assembly of both subunits into an active enzyme. Deficiency of either alpha PCC or beta PCC results in propionic acidemia, an autosomal recessive disorder. We used this expression system to characterize one missense mutation previously described in five Japanese alleles, namely C1283T (Thr428lle) in beta PCC. This mutation, when expressed in E.coli under the same conditions as that of wild-type PCC, had null activity, despite the presence of assembled alpha PCC and beta PCC subunits. This bacterial expression system can be useful for analysis of either alpha PCC or beta PCC mutations. Our findings indicated that the groES and groEL chaperonin proteins were essential for folding and assembly of the human PCC heteromeric subunits.      

A portion of the human surfactant protein A (SP-A) gene locus consists of a pseudogene

SP-A is the most abundant, surfactant-associated protein isolated from lung lavage. Genomic blot analysis of total human cellular DNA with SP-A cDNA demonstrated the presence of multiple hybridizing fragments that are not accounted for by available SP-A gene sequences. In this report, we have cloned and characterized human genomic DNA fragments that account for some of the other hybridizing fragments. These clones contain nucleotide sequences that are highly homologous to the fourth intron and fifth exon of the human SP-A gene. Sequences upstream from these SP-A-like sequences are not detectable by Northern blot hybridization of SP-A-expressing cells and the SP-A-like sequences contain premature stop codons, consistent with the interpretation that these clones represent an SP-A pseudogene. Restriction fragments consistent with this pseudogene and the functional SP-A gene are present in a human chromosome 10 genomic library made from a single chromosome, showing that the functional SP-A gene and the pseudogene are syntenic.