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.     

Radiation enteritis

Acute radiation enteritis is almost inevitable in the curative treatment of malignant tumors of the abdomen and pelvic area. It is frequently a self-limiting disorder of intestinal function associated with reversible mucosal changes of the intestine. The prevalence of chronic radiation enteritis has been underestimated in most surgical series and the majority of patients with symptoms probably do not seek medical advice until a serious complication occurs. Although associated with specific histologic features, the mechanism of chronic radiation injury is poorly understood. The prevalence, pathogenesis, diagnosis and approaches to the treatment and prevention of acute and chronic radiation enteritis are discussed herein. Recent investigative techniques should lead to a better understanding of the physiopathologic characteristics of radiation enteritis and, thereby, provide a more rational basis for treatment which, at the present time, is unsatisfactory. Attempts to reduce the prevalence of radiation enteritis should be directed toward careful patient selection for radiation treatment of the pelvis and to minimize injury to the small intestine, by reducing the volume of small intestine in the radiation area and providing more individualized dosimetry.     

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.      

CDX2 expression is progressively decreased in human gastric intestinal metaplasia, dysplasia and cancer.

Intestinal metaplasia is a key event in multistep gastric carcinogenesis. CDX2, a master regulator of intestinal phenotype, was shown to play a tumor-suppressive role in colon cancer. However, it was reported to be expressed in nearly all gastric intestinal metaplasia and many gastric cancers. As CDX2 is differentially expressed in normal stomach and intestine, we sought to relate the CDX2 expression to gastrointestinal differentiation along gastric carcinogenesis. The expression of CDX2 protein in gastric intestinal metaplasia, dysplasia and cancer was examined and related to their gastrointestinal differentiation. CDX2 expression was significantly decreased in incomplete intestinal metaplasia, which expresses both gastric mucins (MUC5AC and MUC6) and intestinal mucin (MUC2), compared with complete intestinal metaplasia, which expresses intestinal mucin (MUC2) only. Although incomplete intestinal metaplasia morphologically resembles colon, its CDX2 expression was apparently lower than that in the normal colon. Moreover, CDX2 expression was progressively reduced in gastric dysplasia and cancer. The CDX2 expression in gastric cancer was also inversely correlated with the expression of gastric mucins. As incomplete intestinal metaplasia is associated with higher risk of gastric cancer, its lower CDX2 expression compared with that in complete intestinal metaplasia and normal colon epithelium resolved the current contradiction between the tumor-suppressive role of CDX2 in the colon and the high prevalence of CDX2 in intestinal metaplasia. Further decrease of CDX2 expression in gastric dysplasia and cancer suggests that CDX2 plays a similar anticarcinogenic role in intestinal metaplasia as it does in colon. Intestinal metaplasia or dysplasia with low expression of CDX2 may serve as predictive markers for gastric cancer.     

Malignancy may adversely influence the quality and behaviour of oocytes

A case series of eight cycles of in-vitro fertilization (IVF) in five women diagnosed with malignant disorders is presented. These patients chose to defer definitive treatment for a chance for preservation of potential fertility. The response of these patients to ovarian stimulation, and the outcome, was compared with 17 IVF cycles in 12 age- matched patients with isolated tubal infertility. An apparent adverse influence of malignant disease on the quality and behaviour of oocytes was observed. Despite a comparable total number of oocytes per cycle in the two groups, a significantly reduced percentage of mature oocytes was retrieved per cycle from patients with malignant diseases. The oocytes from patients with malignant disorders were of a poorer quality and exhibited a significantly impaired fertilization rate compared to the controls. We propose that neoplastic processes, irrespective of the site or cell of origin, may have a detrimental impact on the biology of oocytes, an effect akin to that seen on spermatozoa in men with certain malignancies.