Diagnosing anaemia in pregnancy in rural clinics: assessing the potential of the Haemoglobin Colour Scale.
Anaemia in pregnancy is a common and severe problem in many developing countries. Because of lack of resources and staff motivation, screening for anaemia is often solely by clinical examination of the conjunctiva or is not carried out at all. A new colour scale for the estimation of haemoglobin concentration has been developed by WHO. The present study compares the results obtained using the new colour scale on 729 women visiting rural antenatal clinics in Malawi with those obtained by HemoCue haemoglobinometer and electronic Coulter Counter and with the assessment of anaemia by clinical examination of the conjunctiva. Sensitivity using the colour scale was consistently better than for conjunctival inspection alone and interobserver agreement and agreement with Coulter Counter measurements was good. The Haemoglobin Colour Scale is simple to use, well accepted, cheap and gives immediate results. It shows considerable potential for use in screening for anaemia in antenatal clinics in settings where resources are limited. (+info
Studies on gonococcus infection. XIV. Cell wall protein differences among color/opacity colony variants of Neisseria gonorrhoeae.
Gonococci from colonies exhibiting optical opacity and dark coloration have surface proteins that are not visualized in isogenic transparent, light-colored colony forms. These "colony opacity-associated proteins" have apparent molecular weights varying from 24,000 to 30,000 by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate; their apparent molecular weights are independent of that for their major outer membrane protein. The opacity-associated proteins are more susceptible to hydrolysis by trypsin than is the major outer membrane protein, but gonococci possessing the opacity-associated protein(s) also show enhanced susceptibility of their major outer membrane proteins to the action of trypsin. These conclusions were reached by comparing the electrophoretic patterns of whole-cell lysates from both "laboratory strains" and several recent clinical isolates of Neisseria gonorrhoeae. (+info
On the validity of blood flow measurement using colored microspheres.
The aim of this study was 1) to investigate the validity of repeated estimations of blood flow using colored microspheres (CMS) and 2) to develop and validate a method that permits four consecutive estimations in the same animal using nonradiolabeled microspheres (NRMS). Several mixtures of different types of microspheres were injected in dogs, with each mixture containing the radiolabeled microspheres (RMS; labeled with 113Sn) with either three CMS, four CMS, or three CMS and one type of fluorescent (crimson labeled) microsphere (FMS). The blood flows estimated with the use of any of the injected microspheres were compared with those measured using the RMS as the "gold standard." The results were analyzed by 1) regression analysis, 2) variance analysis (ANOVA I), and 3) estimation of the limits of agreement between RMS and NRMS flow rates. The results indicate that simultaneous estimations of blood flow obtained with the use of more than three CMS lack accuracy and reliability. A combination of three types of CMS with crimson-labeled FMS, however, offers the possibility to estimate consecutively four different flow rates in the same animal in an accurate way and with relatively high precision. (+info
Microinjected glutathione reductase crystals as indicators of the redox status in living cells.
The flavoenzyme glutathione reductase catalyses electron transfer reactions between two major intracellular redox buffers, namely the NADPH/NADP+ couple and the 2 glutathione/glutathione disulfide couple. On this account, microcrystals of the enzyme were tested as redox probes of intracellular compartments. For introducing protein crystals into human fibroblasts, different methods (microinjection, particle bombardment and optical tweezers) were explored and compared. When glutathione reductase crystals are present in a cytosolic environment, the transition of the yellow Eox form to the orange-red 2-electron reduced charge transfer form, EH2, is observed. Taking into account the midpoint potential of the Eox/EH2 couple, the redox potential of the cytosol was found to be < -270 mV at pH 7.4 and 37 degrees C. As a general conclusion, competent proteins in crystalline--that is signal-amplifying--form are promising probes for studying intracellular events. (+info
Light-dependent translocation of a phytochrome B-GFP fusion protein to the nucleus in transgenic Arabidopsis.
Phytochrome is a ubiquitous photoreceptor of plants and is encoded by a small multigene family. We have shown recently that a functional nuclear localization signal may reside within the COOH-terminal region of a major member of the family, phytochrome B (phyB) (Sakamoto, K., and A. Nagatani. 1996. Plant J. 10:859-868). In the present study, a fusion protein consisting of full-length phyB and the green fluorescent protein (GFP) was overexpressed in the phyB mutant of Arabidopsis to examine subcellular localization of phyB in intact tissues. The resulting transgenic lines exhibited pleiotropic phenotypes reported previously for phyB overexpressing plants, suggesting that the fusion protein is biologically active. Immunoblot analysis with anti-phyB and anti-GFP monoclonal antibodies confirmed that the fusion protein accumulated to high levels in these lines. Fluorescence microscopy of the seedlings revealed that the phyB-GFP fusion protein was localized to the nucleus in light grown tissues. Interestingly, the fusion protein formed speckles in the nucleus. Analysis of confocal optical sections confirmed that the speckles were distributed within the nucleus. In contrast, phyB-GFP fluorescence was observed throughout the cell in dark-grown seedlings. Therefore, phyB translocates to specific sites within the nucleus upon photoreceptor activation. (+info
A functional neuroimaging study of the variables that generate category-specific object processing differences.
Brain damage can cause remarkably selective deficits in processing specific categories of objects, indicating the high degree of functional segregation within the brain. The neuroimaging study presented here investigates differences in the neural activity associated with two categories of natural objects (animals and fruit) and two categories of man-made objects (vehicles and tools). Stimuli were outline drawings and the tasks were naming and word-picture matching. For man-made objects, the only category-specific effect was in the left posterior middle temporal cortex, which was most active for drawings of tools, as previously reported. For natural objects, drawings of animals and fruit (relative to drawings of man-made objects) enhanced activity in bilateral anterior temporal and right posterior middle temporal cortices. Critically, these effects with natural objects were not observed when the stimuli were coloured appropriately to facilitate identification. Furthermore, activation in the same right hemisphere areas was also observed for viewing and matching unfamiliar non-objects relative to naming and matching man-made objects. These results indicate that, in the right hemisphere, differences between processing natural relative to man-made objects overlap with the effects of increasing demands on object identification. In the left hemisphere, the effects are more consistent with functional specialization within the semantic system. We discuss (i) how category-specific differences can emerge for multiple reasons and (ii) the implications of these effects on the interpretation of functional imaging data and patients with category-specific deficits. (+info
Characterization of color mutants in lacZ plasmid-based transgenic mice, as detected by positive selection.
The plasmid-based transgenic mouse model, which uses the lacZ gene as the target for mutation, is sensitive to a wide range of in vivo mutations, ranging from point mutations to insertions and deletions extending far into the mouse genome. In this study, the nature of subtle lacZ mutations, which do not completely abolish beta-galactosidase activity, as detected by positive selection, was investigated. These subtle mutants are called 'color mutants' due to their light blue staining on X-gal medium. Replating of color mutants and retransformation of plasmid DNA, purified from individual color mutants, resulted in the same phenotype as the original color mutant. The p-gal positive selection system tolerates approximately 10% of wild-type activity as indicated by spectrophotometric determination of beta-galactosidase activity of individual color mutants. Restriction digestion and size separation of plasmid DNA revealed no visible change in the size of the plasmid in color mutants. Sequence analysis confirmed the presence of a point mutation in each lacZ gene of nine different color mutants. The results indicate that color mutants are caused neither by the presence of a mixture of wild-type and mutated lacZ plasmids within the same host cell nor by a mixture of cells within the original mutant colony which carry either wild-type or mutated lacZ plasmids. In addition, it was discovered that the mouse line studied harbors four polymorphic base changes among the integrated plasmid copies. (+info
Evaluation of corneal thickness and topography in normal eyes using the Orbscan corneal topography system.
AIMS: To map the thickness, elevation (anterior and posterior corneal surface), and axial curvature of the cornea in normal eyes with the Orbscan corneal topography system. METHODS: 94 eyes of 51 normal subjects were investigated using the Orbscan corneal topography system. The anterior and posterior corneal elevation maps were classified into regular ridge, irregular ridge, incomplete ridge, island, and unclassified patterns, and the axial power maps were grouped into round, oval, symmetric bow tie, asymmetric bow tie, and irregular patterns. The pachymetry patterns were designated as round, oval, decentred round, and decentred oval. RESULTS: The thinnest point on the cornea was located at an average of 0.90 (SD 0. 51) mm from visual axis and had an average thickness of 0.55 (0.03) mm. In 69.57% of eyes, this point was located in the inferotemporal quadrant, followed by the superotemporal quadrant in 23.91%, the inferonasal quadrant in 4.35%, and the superonasal quadrant in 2.17%. Among the nine regions of the cornea evaluated (central, superotemporal, temporal, inferotemporal, inferior, inferonasal, nasal, superonasal, and superior) the central cornea had the lowest average thickness (0.56 (0.03) mm) and the superior cornea had the greatest average thickness (0.64 (0.03) mm). The mean simulated keratometry (SimK) was 44.24 (1.61)/43.31 (1.66) dioptres (D) and the mean astigmatism was 0.90 (0.41) D. Island (71.74%) was the most common elevation pattern observed in the anterior corneal surface, followed by incomplete ridge (19.57%), regular ridge (4.34%), irregular ridge (2.17%), and unclassified (2.17%). Island (32.61%) was the most common topographic pattern in the posterior corneal surface, following by regular ridge (30.43%), incomplete ridge (23. 91%), and irregular ridge (13.04%) patterns. Symmetric bow tie was the most common axial power pattern in the anterior cornea (39.13%), followed by oval (26.07%), asymmetric bow tie (23.91%), round (6. 52%), and irregular (4.53%) patterns. In the pachymetry maps, 47.83% of eyes had an oval pattern, and round, decentred oval, and decentred round were observed in 41.30%, 8.70%, and 2.18% of eyes, respectively. CONCLUSION: The information on regional corneal thickness, corneal elevation and axial corneal curvature obtained with the Orbscan corneal topography system from normal eyes provides a reference for comparison with diseased corneas. The Orbscan corneal topography system is a useful tool to evaluate both corneal topography and corneal thickness. (+info