Buried Kirschner wire fixation of the Austin osteotomy-bunionectomy: a preliminary report

Austin bunionectomies were fixated with buried 0.062-inch Kirschner wire. The wires were surgically removed in 7 to 10 weeks, when radiographic union was demonstrated. This approach allows confident early range-of-motion exercises and return to normal footwear. Intermetatarsal angles were reduced 6 to 12 degrees without displacement. The advantages and disadvantages of this technique are discussed.     

Treatment of dural sinus thrombosis using selective catheterization and urokinase

Thrombosis of the cerebral dural venous sinuses, cortical draining veins, and deep cerebral veins is a rare clinical finding. Because of its low incidence and multiple etiologies, the optimum therapy for this condition will only be elucidated by a multicenter, randomized prospective study. At our institution, we favor early and aggressive management of cerebral venous sinus thrombosis with transfemoral, venous intradural infusions of the fibrinolytic agent urokinase. To date, treatment of only 13 patients using this technique has been reported in the English literature. This report adds 12 more such treated patients. Despite the presence of preinfusion infarcts in 5 patients, four of which were hemorrhagic, we incurred no major therapeutic morbidity. Functional sinus patency was achieved in 11 of 12 patients, with our only true failure occurring in an individual with symptoms of at least 2 months' duration. Good to excellent clinical outcome was achieved in 10 of 11 patients (one newborn had inadequate follow-up).     

The involvement of interdigitating (antigen-presenting) cells in the pathogenesis of rheumatoid arthritis.

Macrophage like cells expressing high concentrations of HLA-DR antigen have been identified in situ within the synovium of patients with rheumatoid arthritis. The characteristics of these cells have been determined using immunohistological analysis and combined cytochemical techniques. It was found that the majority (greater than 80%) of these cells were interspersed within the perivascular lymphocytic infiltrates occurring in the synovium. These cells did not stain with antisera against surface immunoglobulin or any Mc Abs to T lymphocyte markers. Further combined staining demonstrated that the HLA-DR + ve cells did stain with an anti-monocyte monoclonal (FMC-17), but could not be stained with a Mc Ab against C3b receptors. The interfacing of cytochemical reactions for acid phosphatase (ACP) and adenosine triphosphatase (ATPase) with immunofluorescence staining for HLA-DR demonstrated that these cells were ACP - ve ATPase + ve. This analysis led to the conclusion that the HLA-DR + ve cells found in abundance in the rheumatoid synovium expressed identical characteristics to the interdigitating cells of the normal lymph node paracortex. The possible significance of the presence of large numbers of such antigen presenting cells in the rheumatoid synovium is discussed.     

The search for a marsupial XIC reveals a break with vertebrate synteny

X-chromosome inactivation (XCI) evolved in mammals to deal with X-chromosome dosage imbalance between the XX female and the XY male. In eutherian mammals, random XCI of the soma requires a master regulatory locus known as the ‘X-inactivation center’ (XIC/Xic), wherein lies the noncoding XIST/Xist silencer RNA and its regulatory antisense Tsix gene. By contrast, marsupial XCI is imprinted to occur on the paternal X chromosome. To determine whether marsupials and eutherians share the XIC-driven mechanism, we search for the sequence equivalents in the genome of the South American opossum, Monodelphis domestica. Positional cloning and bioinformatic analysis reveal several interesting findings. First, protein-coding genes that flank the eutherian XIC are well-conserved in M. domestica, as well as in chicken, frog, and pufferfish. However, in M. domestica we fail to identify any recognizable XIST or TSIX equivalents. Moreover, cytogenetic mapping shows a surprising break in synteny with eutherian mammals and other vertebrates. Therefore, during the evolution of the marsupial X chromosome, one or more rearrangements broke up an otherwise evolutionarily conserved block of vertebrate genes. The failure to find XIST/TSIX in M. domestica may suggest that the ancestral XIC is too divergent to allow for detection by current methods. Alternatively, the XIC may have arisen relatively late in mammalian evolution, possibly in eutherians with the emergence of random XCI. The latter argues that marsupial XCI does not require XIST and opens the search for alternative mechanisms of dosage compensation.     

Evaluation of serotype prediction by cpsA-cpsB gene polymorphism in Streptococcus pneumoniae

New pneumococcal conjugate vaccines covering a limited number of serotypes are likely to come into widespread use over the next few years. It is unknown what effect this will have on the relative importance of different serotypes as causes of pneumococcal infection. Hence, it will be important to monitor serotype prevalence before, during, and after the introduction of new vaccines. We have investigated the ability of a PCR method based on polymorphisms in two genes common to the different capsule loci to predict the serotype of 93 clinical isolates of Streptococcus pneumoniae submitted to the Central Public Health Laboratory in 1997. Of 70 isolates with vaccine serotypes, 65 were predicted to belong to the correct serotype; this number was improved to 69 with the inclusion of two additional patterns to the database. Of 23 isolates with other serotypes, 19 were correctly predicted as non-vaccine serotypes, the discrepancy lying with four isolates of 6A (non-vaccine serotype) that were indistinguishable from isolates of 6B (vaccine serotype). In situations in which culture of the organism is not feasible, this method could potentially be applicable directly to clinical specimens and could be a valuable aid to the surveillance of pneumococcal serotypes.     

Mechanism of pellet egestion in great-horned owls (Bubo virginianus).

To study the mechanism of oral pellet egestion in great-horned owls, bipolar electrodes and strain-gauge transducers were chronically implanted in the esophagus, muscular stomach, and duodenum of six owls. Recordings from conscious owls plus simultaneous radiographic observations revealed characteristic gastrointestinal motility patterns associated with egestion. Beginning at about 12 min before egestion, gastric contractions formed the final shape of the pellet and pushed it into the lower esophagus. The pellet was moved out of the esophagus by antiperistalsis during the last 8--10 s before egestion. During pellet egestion, contractions of abdominal muscles were not detected. Pellet egestion appears to be unlike either emesis in mammals with a simple stomach or regurgitation in ruminants.     

Effects of cyclopiazonic acid on Ca2+ regulation by the sarcoplasmic reticulum in saponin-permeabilized skeletal muscle fibres

 The effects of the sarcoplasmic reticulum (SR) Ca²⁺ pump inhibitor cyclopiazonic acid (CPA) were studied in saponin-permeabilized frog skeletal muscle fibres. Release of Ca²⁺ from the SR was triggered by brief (2 s) applications of 40 mM caffeine at 2-min intervals. Changes in [Ca²⁺] within the fibre were monitored continuously using Fura-2 fluorescence. At a bathing [Ca²⁺] of 100 nM, introduction of 20 μM CPA induced a slow release of Ca²⁺ from the SR. The following one to two caffeine-induced Ca²⁺ transients were markedly increased in amplitude and duration. Thereafter, the caffeine-induced Ca²⁺ transients decreased progressively and were barely detectable 6–7 min after introduction of CPA. However, increasing the bathing [Ca²⁺] or increasing the Ca²⁺ loading period resulted in a partial recovery of the caffeine-induced Ca²⁺ transients, suggesting that pump inhibition is incomplete, even in the presence of 100 μM CPA. The slow Ca²⁺ efflux induced by CPA was insensitive to ryanodine, but absent following abolition of SR Ca²⁺ pump activity by ATP withdrawal. These results suggest that the caffeine-induced Ca²⁺ transient reflects a balance between efflux via the SR Ca²⁺ channel and reuptake by the Ca pump. Ca²⁺ release upon addition of CPA may result from inhibition of SR Ca²⁺ uptake, which reveals a tonic Ca²⁺ efflux that is independent of the Ca²⁺ release channels. Received: 26 November 1997 / Received after revision: 12 January 1998 / Accepted: 13 January 1998