Fine-scale processing in human binocular stereopsis

Many studies have demonstrated that the human visual system is sensitive to very small differences in relative binocular disparity. It is not known over what monocular regions information is spatially integrated to mediate performance in such tasks. In this study we present psychophysical observations that define the smallest spatial scale involved in disparity processing, and we indicate the nature of the computations performed by the units mediating that disparity discrimination. We show that human observers can identify the sign of disparity of a single target dot when it is embedded in a row of identical dots, with these noise dots presented either in the fixation plane or with a proportion binocularly uncorrelated. In conjunction with the psychophysical data, we explore how a class of simple correlator models of stereopsis must be constrained in order to account for human performance for the same fine-scale tasks. Such models can perform the task only when the correlation is carried out over a very small region of the image, for a very small range of disparities. Our results demonstrate that there is a fine-scale input to the stereo system, mediated by foveal mechanisms that spatially integrate visual signals over a region as small as 4-6 arcmin in diameter.     

Recovery of phenanthrene-degrading bacteria after simulated in situ persulfate oxidation in contaminated soil

A continuous-flow column study was conducted to investigate the long-term effects of persulfate oxidation on the abundance and activity of the indigenous microbial community and phenanthrene-degrading bacteria in contaminated soil from a former manufactured gas plant (MGP) site. Approximately six pore volumes of a 20 g/L persulfate solution were introduced into the column, followed by simulated groundwater for 500 days. Soil samples were collected from the surface of the soil bed and along the column length immediately before and after persulfate injection and up to 500 days following injection. Exposure to persulfate led to a 2- to 3-log reduction in total bacterial 16S rRNA genes, severe inhibition of (14)C-acetate mineralization (as a measure of general microbial activity), and a decrease in community diversity. However, relatively rapid recovery of both bacterial gene abundance and activity was observed within 30 days after persulfate exposure. Mineralization of (14)C-phenanthrene was also inhibited but did not recover until 100 days postoxidation. Known phenanthrene-degrading bacterial groups decreased to below detection limits throughout the column, with recovery times from 100 to 500 days after persulfate injection. These findings suggest that coupling biological processes with persulfate oxidation is possible, although recovery of specific contaminant degraders may occur much later than the general microbial community recovers. Furthermore, the use of total bacterial quantity or nonspecific measures of activity as a surrogate for the recovery of contaminant degraders may be inappropriate for evaluating the compatibility of chemical treatment with subsequent bioremediation.     

Identification of a novel endogenous memory facilitating cyclic dipeptide cyclo-prolylglycine in rat brain

Using high-performance liquid chromatography, gas-chromatography and chromato-mass spectrometry methods a novel endogenous cyclic dipeptide cyclo-prolylglycine was identified in rat brain. Its content according to gas chromatography is 2.8 +/- 0.3 nmol/g wet brain. Synthetic cyclo-prolylglycine has demonstrated antiamnesic activity in the passive avoidance test in rats at a dose of 0.1 mg/kg i.p. Cyclic dipeptide cyclo-prolylglycine seems to be a memory facilitating substance and its presence in rat brain suggests the existence of a new mechanism of memory regulation.     

The management of malnutrition in hospital

Treatable malnutrition may occur in up to 25% of hospital patients, depending on the specialty concerned. Nutritional status may also deteriorate during a prolonged hospital stay. The management and prevention of malnutrition requires a climate in which hospital managers have a positive policy towards nutritional care, a screening system to identify the patients at risk, and appropriate protocols for action. Catering services need to be reorganized to address the problems of the sick, so that appropriate food is not only prepared but delivered in a way which makes it likely to be consumed. For the optimal management of artificial nutrition by the enteral or parenteral route, a skilled nutrition team is both necessary and cost-effective.     

In vivo electrochemical studies of dopamine overflow and clearance in the striatum of normal and MPTP-treated rhesus monkeys

Translational recruitment of maternal mRNAs is an essential process in early metazoan development. To identify genes required for this regulatory pathway, we have examined a collection of Drosophila female-sterile mutants for defects in translation of maternal mRNAs. This strategy has revealed that maternal-effect mutations in the cortex and grauzone genes impair translational activation and cytoplasmic polyadenylation of bicoid and Toll mRNAs. Cortex embryos contain a bicoid mRNA indistinguishable in amount, localization, and structure from that in wild-type embryos. However, the bicoid mRNA in cortex embryos contains a shorter than normal polyadenosine (poly(A)) tail. Injection of polyadenylated bicoid mRNA into cortex embryos allows translation demonstrating that insufficient polyadenylation prevents endogenous bicoid mRNA translation. In contrast nanos mRNA, which is activated by a poly(A)-independent mechanism, is translated in cortex embryos, indicating that the block in maternal mRNA activation is specific to a class of mRNAs. Cortex embryos are fertilized, but arrest at the onset of embryogenesis. Characterization of grauzone mutations indicates that the phenotype of these embryos is similar to cortex. These results identify a fundamental pathway that serves a vital role in the initiation of development.     

Case report of ruptured endometriotic cyst in pregnancy treated by laparoscopic ovarian cystectomy

Pregnancy is thought to have an ameliorating effect on endometriosis, inducing a state of quiescence. We report a case of ruptured endometriotic cyst in pregnancy successfully treated by laparoscopic ovarian cystectomy. Our patient subsequently progressed uneventfully to deliver a healthy baby girl at term. Laparoscopic ovarian cystectomy in pregnancy, even with ruptured cysts, appeared to be safe in trained hands with similar benefits of reduced post-operative morbidity.     

Case of the month: April 1998--30 year old male with perineal numbness

A 30-year-old male presented with a 2 year progressive course of bowel and bladder dysfunction, mild leg weakness and sensory abnormalities in sacral dermatomes. MRI showed an intra-axial conus medullaris lesion which was excised and identified as a ganglioglioma. The case presents the typical clinical course and histopathology of this unusual lesion which carries a favorable prognosis after gross total removal. Preoperative neurological function in such patients is highly predictive of post-operative outcome.     

Repression of c-fos and c-jun gene expression is not part of AT2 receptor coupled signal transduction

Recent world-wide publications were reviewed in order to determine the clinical characteristics and therapeutic relevance of the chlamydial respiratory tract infections in humans. It was emphasized that Chlamydia pneumoniae could initiate asthma and may be associated with acute asthma exacerbation. Laboratory procedures for identifying chlamydia and difficulties concerned with the diagnostics of this intracellular pathogen were also presented. In patients with evidence of chlamydial infection the casual treatment (macrolides, tetracyclines, fluoroquinolones) may induce major improvement or complete resolution of asthma.