Osteochondral Fracture of the Fourth Metatarsal Head Treated by Open Reduction and Internal Fixation

Fracture of the metatarsal head is uncommon, and reports of isolated osteochondral fracture of the metatarsal head are rare. Because of the distal location of the fracture, it is difficult to achieve and maintain reduction, and potential complications include avascular necrosis and subchondral fatigue fracture. The authors present a case of an osteochondral fracture in a 40-year-old man, which was treated by open reduction and internal fixation with a single twist-off screw, with good results 12 months postoperatively.     

Experimental columnar metaplasia in the canine oesophagus

Regeneration of canine oesophageal mucosa was studied under basal conditions and in the presence of gastro-oesophageal reflux. In normal circumstances mucosal defects in the oesophagus regenerate by squamous epithelium. In the presence of gastro-oesophageal reflux of either acid or a combination of acid and bile, regeneration was frequently by columnar epithelium (Barrett's oesophagus). This columnar regeneration was not seen with bile reflux alone. By the use of squamous barriers to proximal migration of columnar epithelium in the stomach, it was demonstrated that columnar re-epithelialization may occur from cells intrinsic to the oesophagus and is not dependent on proximal migration of cardiac columnar epithelium. The cell of origin of this epithelium may be located in oesophageal gland ducts and is likely to be a multipotential stem cell since the regenerated columnar epithelium may contain goblet and parietal cells not normally found in the oesophagus. This epithelium is morphologically distinct on mucin histochemistry from cardiac columnar epithelium. These findings support the concept that Barrett's epithelium is metaplastic.     

The apolipoprotein C-II variant apoC-IILys19→Thr is not associated with dyslipidemia in an affected kindred

The rare apolipoprotein C-II (apoC-II) mutation, apoC-II_Lys19→Thr, also known as apoC-II-v, has been found previously in association with hyperlipoproteinemia. From a lipid clinic screening we identified three unrelated individuals who had the apoC-II_Lys19→Thr mutation. Among eight family members of one proband, we have found another four who were affected. None of the inviduals in this kindred is dyslipidemic and there is no difference in lipid levels between affected and unaffected family members. Therefore, we conclude that the presence of this apolipoprotein variant by itself has no effect on lipoprotein levels. In addition, the apolipoprotein E (apoE) isoform, apoE4 does not have a synergistic effect on lipoprotein levels in this kindred, in contrast to observations on the interaction of apoE4 with another apoC-II mutant (apoC-II_Toronto). The single nucleotide substitution that causes the apoC-II_Lys19→Thr variant introduces a previously unrecognized restriction site (for Mae III), that provides for easy screening.     

A group of interacting yeast DNA replication genes

Mutations in the cell-division-cycle genes CDC46 and CDC47 were originally isolated as suppressors of mutations in two other cell-division-cycle genes (CDC45 and CDC54). We found several combinations of mutations in these genes that result in allele-specific suppression and synthetic lethality, confirming that this set of genes forms a group of genetically interacting components. Here, we show that the other genes, like CDC46, are all involved in an early step of DNA replication, possibly initiation of DNA synthesis. Mutants defective in each of the four genes exhibit high rates of mitotic chromosome loss and recombination. The mutants appear also to accumulate chromosome damage that can be detected by a novel chromosome electrophoresis assay. Conditional mutants in this group, under fully nonpermissive conditions, show cell-cycle arrest at the beginning of DNA synthesis; under less stringent conditions, some arrest later, in S-phase. The DNA sequence of the CDC46 gene indicates that the protein is a member of a new family of genes apparently required for DNA initiation, with family members now identified in Saccharomyces cerevisiae, Schizosaccharomyces pombe, and mouse cells.