[A rare cause of cauda equina syndrome: primary epidural lymphoma]. / Une cause rare de syndrome de la queue de cheval: Le lymphome epidural primitif.

INTRODUCTION: Primary epidural lymphoma is generally manifested by isolated epidural involvement. On rare occasions it can lead to cauda equina syndrome. CASE: A 56-year-old man was hospitalized for lumbago, weakness in the legs and sphincter problems. A dorsolumbar MRI revealed that the anterior and posterior peridural space from D11 to L3 was filled by a mass compressing the marrow and compacting the roots. The L2 to L4 laminectomy revealed an extradural tissue leading to the diagnosis of large B-cell lymphoma. Metastatic workup demonstrated unremarkable findings. DISCUSSION: Primary epidural lymphoma accounts for less than 10% of epidural tumours and less than 1% of non-Hodgkin lymphomas. Its clinical manifestations are related to the tumoral process or involvement of medullar vessels. It can be, but rarely is, manifested by cauda equina syndrome. Diagnosis is based on histological analysis of tissue taken during the decompression laminectomy. Prognosis is relatively good.

Genome scanning in Haemophilus influenzae for identification of essential genes.

We have developed a method for identifying essential genes by using an in vitro transposition system, with a small (975 bp) insertional element containing an antibiotic resistance cassette, and mapping these inserts relative to the deduced open reading frames of Haemophilus influenzae by PCR and Southern analysis. Putative essential genes are identified by two methods: mutation exclusion or zero time analysis. Mutation exclusion consists of growing an insertional library and identifying open reading frames that do not contain insertional elements: in a growing population of bacteria, insertions in essential genes are excluded. Zero time analysis consists of monitoring the fate of individual insertions after transformation in a growing culture: the loss of inserts in essential genes is observed over time. Both methods of analysis permit the identification of genes required for bacterial survival. Details of the mutant library construction and the mapping strategy, examples of mutant exclusion, and zero time analysis are presented.

Isolation of isoflavones from soy-based fermentations of the erythromycin-producing bacterium Saccharopolyspora erythraea.

A search for an abundant and economical source of isoflavones, particularly genistein, led to the discovery that the erythromycin-producing organism Saccharopolyspora erythraea also produces this promising new cancer-prevention agent. Erythromycin fermentation is a large-scale, soybean-based process used world-wide for the commercial production of this medically important antibiotic. Results from this study indicate that genistin (the glucoside form of genistein), which is added to the fermentation in the soybean media, was converted to genistein through the action of a beta-glucosidase produced by the organism. Genistein was co-extracted with erythromycin from the fermentation broth, then separated from erythromycin during the second step of the purification process for the production of erythromycin.

Separation of left and right skull bones from low angle x-ray projections.

This study shows how two layers which are superposed in two low angle x-ray projections can be reconstructed separately without having any a priori knowledge of their shape. Similar to stereoscopic imaging, the projections of the two layers appear at different positions in the two superposition images. Matching one of the layers allows its elimination by subtraction. The resulting difference signal is the so-called 'movement artefact' of the second, mismatched layer. A filter method is developed to reconstruct this layer from the spectrum of its artefact within the Fourier domain. The second layer is reconstructed in an analogous way. So, for example, the bones of the left and the right side of the human skull can be imaged separately. This is used to reduce image artefacts caused by patient movements in subtraction angiography and tumourfluoroscopy of the brain.

Phosphoribulokinase activity and regulation of CO2 fixation critical for photosynthetic growth of Rhodobacter sphaeroides.

The Rhodobacter sphaeroides genome contains two unlinked genetic regions each encoding numerous proteins involved in CO2 fixation which include phosphoribulokinases (prkA and prkB), ribulose 1,5-bisphosphate carboxylase/oxygenase (rbcLS and rbcR) (P. L. Hallenbeck and S. Kaplan, Photosynth. Res. 19:63-71, 1988; F. R. Tabita, Microbiol. Rev. 52:155-189, 1988), and two open reading frames linked to rbcLS and rbcR, namely, cfxA and cfxB, respectively (P. L. Hallenbeck, R. Lerchen, P. Hessler, and S. Kaplan, J. Bacteriol. 172:1736-1748). In this study, we examined the unique role(s) of each phosphoribulokinase activity in the regulation of CO2 fixation. Strains were constructed which contain null mutations in prkA and/or prkB. Studies utilizing these strains suggested that CO2 fixation plays an essential role in attaining the cellular redox balance necessary for photoheterotrophic growth. The presence of an external electron acceptor can negate the requirement for CO2 for photoheterotrophic growth. Each form of phosphoribulokinase and ribulose 1,5-bisphosphate carboxylase/oxygenase was shown to have distinct roles in CO2 metabolism when cells were exposed to extremes in CO2 levels. Evidence is also presented which unequivocally demonstrated that regulation of the expression of the enzymes involved in CO2 metabolism is effective at the transcriptional level. Although the two regions of the DNA involved in CO2 fixation are physically unlinked, each region of the DNA can have a profound effect on the expression of the other region of the DNA.

Roles of CfxA, CfxB, and external electron acceptors in regulation of ribulose 1,5-bisphosphate carboxylase/oxygenase expression in Rhodobacter sphaeroides.

The Rhodobacter sphaeroides genome contains two unlinked genetic regions each encoding a series of proteins involved in CO2 fixation which include phosphoribulokinase (prkA and prkB) and ribulose 1,5-bisphosphate carboxylase/oxygenase (rbcLS and rbcR) (P. L. Hallenbeck and S. Kaplan, Photosynth. Res. 19:63-71, 1988; F. R. Tabita, Microbiol. Rev. 52:155-189, 1988). We examined the effect of CO2 in the presence and absence of an alternate electron acceptor, dimethyl sulfoxide, on the expression of rbcR and rbcLS in photoheterotrophically grown R. sphaeroides. The expression of both rbcR and rbcLS was shown to depend on the CO2 concentration when succinate was used as the carbon source. It was also demonstrated that CO2 fixation is critical for photoheterotrophic growth but could be replaced by the alternative reduction of dimethyl sulfoxide to dimethyl sulfide. Dimethyl sulfoxide severely depressed both rbcR and rbcLS expression in cells grown photoheterotrophically at CO2 concentrations of 0.05% or greater. However, cells grown photoheterotrophically in the absence of exogenous CO2 but in the presence of dimethyl sulfoxide had intermediate levels of expression of rbcL and rbcR, suggesting partially independent control by limiting CO2 tension. We also present evidence for the existence of two gene products, namely, CfxA and CfxB, which are encoded by genes immediately upstream of rbcLS and rbcR, respectively. Strains were constructed which contained null mutations in cfxA and/or cfxB. Each mutation eliminated expression of the linked downstream rbc operon. Further, studies utilizing these strains demonstrated that each form of ribulose 1,5-bisphosphate carboxylase/oxygenase plays an essential role in maintaining the cellular redox balance during photoheterotrophic growth at differing CO2 concentrations.

High accuracy sonographic recognition of gallstones.

Recent advances in the imaging capabilities of gray scale sonography have increased the accuracy with which gallstones may be diagnosed. Since the sonographic diagnosis of gallstones is often followed by surgery without further confirmatory studies, the avoidance of false-positive diagnoses assumes major importance. In an attempt to improve diagnostic accuracy, 420 gallbladder sonograms were evaluated for gallstones. Positive diagnoses were limited to cases in which the gallbladder was well visualized and contained densities that produced acoustic shadowing or moved rapidly with changes in position. Gallstones were diagnosed in 123 cases and surgery or autopsy in 70 of these patients confirmed stones in 69. There was one false-positive, an accuracy rate for positive diagnosis of 98.6%. Five cases were called indeterminate for stones; one of these had tiny 1 mm stones at surgery. The other four cases had no surgery. Of 276 cases called negative for stones. None of the 146 cases with negative sonograms and oral cholecystography or intravenous cholangiography had stones diagnosed by these methods. Because of its ease and simplicity, sonography is attractive as the initial study in patients suspected of having gallstones. With the criteria used here, a diagnosis of gallstones in the gallbladder can be offered with great confidence.

Renal adenocarcinoma in an asymptomatic 19-year-old female.

Renal adenocarcinoma is rare before age 20. Clinically and radiographically, it presents similarly in adults and children. Prognosis is related to the clinical stage of the tumor at surgery. Treatment methods are still under investigation.

Adenocarcinoma of the duodenum arising in a villous adenoma.

Duodenal villous adenomas are premalignant lesions. Prior to malignant transformation, their appearance on upper gastrointestinal examination is often characteristic. Following malignant change, the final diagnosis frequently requires tissue.