The dose-response for x-ray induction of myeloid leukaemia in male CBA/H mice

The form of the dose-response for induction of malignant diseases in vivo by ionizing radiation is not yet established in spite of its scientific interest and its practical importance. Considerably extended observations have confirmed that the dose-response for acute myeloid leukaemia induced in male CBA/H mice by X-ray exposure is highly curvilinear. The dose-response was well fitted by the expression aD2e-lambda D (D = dose) in agreement with induction at the cellular level in proportion to D2 over the whole dose range 0.25-6.0 Gy. The factor e-lambda D accounts for the inescapable concomitant inactivating action of the inducing irradiation. The quantitative aspects of induction of myeloid leukaemia by ionizing radiation are unlike the induction of genetic mutation or cell inactivation and suggest that interaction of two adjoining cells is an essential element in radiation leukaemogenesis.     

Tarsal navicular stress fractures: radiographic evaluation

Tarsal navicular stress fractures are a potential source of disabling foot pain in physically active individuals. The diagnosis of tarsal navicular stress fracture requires a high index of clinical and radiographic suspicion because the fracture is only rarely evident on routine radiographs or standard tomograms. The radiographic diagnosis of a tarsal navicular stress fracture may require anatomic anteroposterior tomograms or a radionuclide bone scan with plantar views. Radiographic examinations of 23 fractures in 21 patients are evaluated.     

Identification and characterization of Caenorhabditis elegans palmitoyl protein thioesterase1

Infantile neuronal ceroid lipofuscinosis (INCL; Batten disease) is a severe neurodegenerative disorder of childhood characterized by the accumulation of autofluorescent storage material in lysosomes. It is caused by mutation of the CLN1/PPT1 gene, which encodes the lysosomal enzyme palmitoyl protein thioesterase-1 (PPT1), but the mechanism of disease pathogenesis and substrates for the enzyme are unknown. Caenorhabditis elegans is a simple nematode worm, with a fully sequenced genome, which is easy to maintain and manipulate. It has a completely mapped cell lineage and nervous system and has already provided clues about the pathogenesis of several human neuronal and lysosomal storage disorders. We have identified and characterized a PPT1 homologue in C. elegans. We found that, although this gene was not essential for the animal's survival, its mutation resulted in a mild developmental and reproductive phenotype, affected the number and size of mitochondria, and resulted in an abnormality in mitochondrial morphology, possibly suggestive of a role for this organelle in INCL pathogenesis. This strain, deleted for ppt-1, potentially provides a model system for the study of PPT1 and the pathogenesis of INCL.     

111Indium-labelled red-cell scintigraphy to detect intermittent gastrointestinal bleeding from synchronous small- and large-bowel adenocarcinomas

A 70-year-old woman presented with symptoms of profound anaemia and evidence of intermittent gastrointestinal haemorrhage. Oesophagogastroduodenoscopy, colonoscopy, abdominal computerised tomography, sulphur colloid scintigraphy and selective mesenteric angiography were non-diagnostic. An indium-labelled red-cell scan was performed, which suggested bleeding from the ileum at 36 h. At laparotomy, a primary small-bowel adenocarcinoma was resected. Six weeks later, she was again anaemic. Repeat colonoscopy showed a synchronous primary colonic adenocarcinoma, which had been masked by intraluminal blood during the original indium scan. The lesion was impalpable, even after full mobilisation of the colon. A right hemicolectomy was performed. Indium has a longer half-life (67 h) than the more commonly used technetium isotope (18 h). This allows serial imaging for up to 5 days, which may increase diagnostic efficiency in intermittent gastrointestinal bleeding. Clinicians should be aware that persisting activity from intraluminal blood may mask synchronous lesions.