[With the scalpel against the immune system: HIV infection complicated by an unclear colitis]. / Mit dem Skalpell gegen das Immunsystem: eine unklare Kolitis bei HIV-Infektion.

A 35-year-old Kenian lady with advanced immunodeficiency due to HIV infection started on an antiretroviral therapy. Five months later, a severe colitis was diagnosed, however, no causal pathogen could be found. In order to avoid imminent perforation, a hemicolectomy became necessary, and immediately the symptoms and inflammation markers normalized rapidly. M. tuberculosis could be proven in culture in a draining abdominal lymph node. We assume that the severe inflammation was caused by an immune restoration inflammatory syndrome (IRIS). Essentials in diagnosis, pathogenesis and therapy of IRIS are discussed.

Sharpening stellar images.

Atmospherically induced phase perturbations have for years limited the resolution of large optical astronomical telescopes. A prototype telescope system with six movable elements has successfully corrected these phase perturbations. This use of real-time image sharpening has restored stellar images to the diffraction limit (in one dimension) for a 30-centimeter telescope. The double-star image presented indicates that the bulk of the atmospherically induced wave-front phase change occurred within 2 kilometers of the telescope. This implies that, at least for conditions similar to those of our measurement, real-time correction can be accomplished simultaneously for a region at least several arc seconds in angular size. With the present apparatus the technique should be practical for objects as dim as fifth magnitude, and with improvements the technique holds the promise of active image restoration for objects as dim as ninth magnitude.

Conodont survival and low iridium abundances across the permian-triassic boundary in South china.

The Permian-Triassic sedimentary sequence of China includes one of the most complete and fossiliferous Paleozoic-Mesozoic boundaries known. Closely spaced sampling across the boundary, which is an important extinction event for most organisms, has produced good conodont faunas that show little diversity change. A drop in conodont abundance is the only apparent response to the extinction event. A low concentration of iridium in the boundary clay (0.002 part per billion +/-20 percent), as well as in samples immediately below and above, that range from 0.004 to 0.034 part per billion do not support the proposal of an extraterrestrial impact event at this boundary in China.

Palynological and iridium anomalies at cretaceous-tertiary boundary, South-central Saskatchewan.

The Cretaceous-Tertiary boundary in south-central Saskatchewan is marked by coincident anomalies in abundance of iridium and fern spores at the extinction level of a suite of Cretaceous pollen taxa. Evidence of disruption of the terrestrial flora includes the fern-spore abundance anomaly and local extinction of as much as 30 percent of angiosperm species. The reorganized earliest Tertiary flora is made up largely of surviving species that assumed new roles of dominance. Persistence of climatically sensitive taxa across the boundary indicates that if paleoclimate was altered by the terminal Cretaceous event, it returned quickly to the pre-event condition.

A search for iridium abundance anomalies at two late cambrian biomere boundaries in Western utah.

Iridium concentrations have been measured in samples taken across two Late Cambrian biomere boundaries (crisis zones) in search of evidence for possible elemental abundance anomalies similar to the one observed at the Cretaceous-Tertiary boundary. Sampling was performed in uplifted marine limestone deposits in the House Range of western Utah. Although the two trilobite-brachiopod extinction boundaries could be assigned to +/-4 millimeters of vertical section by laboratory examination of the rocks, only background amounts of iridium (2 x 10(-12) to 17 x 10(-12) gram per gram of whole rock) were observed.

Geologic framework of nonmarine cretaceous-tertiary boundary sites, raton basin, new Mexico and colorado.

Iridium concentrations are anomalously high at the palynological Cretaceous-Tertiary boundary in fluvial sedimentary rocks of the lower part of the Raton Formation at several localities in the Raton Basin of New Mexico and Colorado. The iridium anomaly is associated with a thin bed of kaolinitic claystone in a discontinuous carbonaceous shale and coal sequence.

Disruption of the terrestrial plant ecosystem at the cretaceous-tertiary boundary, Western interior.

The palynologically defined Cretaceous-Tertiary boundary in the western interior of North America occurs at the top of an iridium-rich clay layer. The boundary is characterized by the abrupt disappearance of certain pollen species, immediately followed by a pronounced, geologically brief change in the ratio of fern spores to angiosperm pollen. The occurrence of these changes at two widely separated sites implies continentwide disruption of the terrestrial ecosystem, probably caused by a major catastrophic event at the end of the period.

Iridium anomaly in the upper devonian of the canning basin, Western australia.

A moderate iridium anomaly, about 20 times the local background, has been found in Upper Devonian rocks in the Canning Basin. It occurs at or near the Frasnian-Famennian boundary, which is known to be associated with a major massextinction event of global extent. The anomaly occurs in an extremely condensed limestone sequence laid down under quiet deepwater conditions. Its occurrence suggests a causal link with some form of meteoroid impact. Moreover, carbon isotope data indicate that a large reduction in biomass could have occurred at this level. However, the anomaly coincides with a stromatolite bed containing the fossil cyanobacterium Frutexites; iridium, platinum, iron, manganese, cobalt, arsenic, antimony, and cerium are preferentially concentrated in filaments of this organism, with concentrations ranging from two to five times that of the matrix. It is possible that Frutexites extracted these elements directly from seawater, without the need for their derivation from an extraterrestrial source.

An iridium abundance anomaly at the palynological cretaceous-tertiary boundary in northern new Mexico.

An iridium abundance anomaly, with concentrations up to 5000 parts per trillion over a background level of 4 to 20 parts per trillion, has been located in sedimentary rocks laid down under freshwater swamp conditions in the Raton Basin of northeastern New Mexico. The anomaly occurs at the base of a coal bed, at the same stratigraphic position at which several well-known species of Cretaceous-age pollen became extinct.

Iridium abundances across the ordovician-silurian stratotype.

Chemostratigraphic analyses in the Ordovician-Silurian boundary stratotype section, bracketing a major extinction event in the graptolitic shale section at Dob's Linn, Scotland, show persistently high iridium concentrations of 0.050 to 0.250 parts per billion. There is no iridiumn concentration spike in the boundary interval or elsewhere in the 13 graptolite zones examined encompassing about 20 million years. Iridium correlated with chromium, both elements showing a gradual decrease with time into the middle part of the Lower Silurian. The chromium-iridium ratio averages about 10(6). Paleogeographic and geologic reconstructions coupled with the occurrence of ophiolites and other deep crustal rocks in the source area suggest that the high iridium and chromium concentrations observed in the shales result from terrestrial erosion of exposed upper mantle ultramafic rocks rather than from a cataclysmic extraterrestrial event.

Maxillary sinus grafting with a nano-structured biomaterial: preliminary clinical and histological results.

BACKGROUND: In this study the potential of a new and entirely synthetic, nano-structured hydroxyapatite-based biomaterial for sinus floor augmentation is evaluated. METHODS: 20 sinus floor elevations were carried out in a total of 20 patients. After a healing period of 6 months, in 10 cases cylinder-shaped bone biopsies were taken from the augmented maxillary region using trephine burs. RESULTS: The healing period progressed without any complications. General and specific histological analysis of the bone biopsies showed a high osteoclast activity at the margin of the biomaterial which was well integrated into the newly formed bone. CONCLUSION: This study demonstrates that new trabecular bone is formed after grafting with the nanocrystalline bone substitute after 6 months. Ongoing histomorphological studies are necessary to quantify the biomaterial-bone ratio and the exact amount of newly built bone in the augmented cavity after 6 months.

Effects of feed restriction and realimentation on digestive and immune function in the Leghorn chick.

How regulatory changes of digestive and immune functions of the gut influence each other has not been sufficiently studied. We tested for simultaneous changes in the digestive physiology and mucosal immune function of the guts of White Leghorn cockerel chicks undergoing food restriction and realimentation. Chicks were assigned to 1 of 3 groups: control = fed ad libitum 7 to 17 d of age; restricted = feed restricted d 12 to 17 (at 2 restriction levels: 54 and 34% ad libitum); refed = feed restricted d 7 to 13 and then fed ad libitum d 14 to 17. Refed chicks exhibited 1 d of hyperphagy and an increase in apparent digestive efficiency following restriction (ANOVA, P < 0.001). Total small intestine mass and duodenal maltase activity differed among the groups in the order refed > control > restricted, as expected (ANOVA, P < 0.05 for both measures). In contrast, there were no significant treatment effects on our measures of gut immune structure and function, including bursa mass, spleen mass, and total IgA content of intestinal flush samples measured with standard ELISA techniques. The results of this study indicated that, during feed restriction and realimentation, some features of gut immune function are maintained unchanged in the face of regulatory changes that influence digestive functions.

Bovine hemoglobin as a potential source of hemoglobin-based oxygen carriers: crosslinking with bis(2,3-dibromosalycyl)fumarate.

Reaction in anaerobic conditions of bovine hemoglobin with bis(2,3-dibromosalycyl)fumarate resulted in new derivatives with P50 in excess of 40 mmHg, as determined at 37 degrees C in 0.15 M Cl- at pH 7.4. Although the chromatographic preparations indicated some heterogeneity of the reacted material, the proteins obtained were homogeneous with regard to sedimentation velocity, which showed the presence of only nondissociable tetrameric species. SDS gel electrophoresis showed the presence of a new band with a mobility corresponding approximately to a molecular mass of 32 kDa, indicating the presence of covalent intramolecular crosslinks between subunit pairs. Chromatographic analyses indicated that both alpha and beta chains were chemically modified. The retention times in rats of the crosslinked hemoglobin was 10-times longer than that of untreated hemoglobin.

Oral ulcerations with use of hydrogen peroxide.

Hydrogen peroxide has been advocated for many years as an oral rinse useful in control of various oral conditions. Several authorities, however, have suggested that this material may be harmful to oral tissues, especially if the tissues have been previously injured. This article presents two case reports demonstrating harmful oral effects from hydrogen peroxide rinses. The findings suggest that oral hygiene techniques emphasizing the use of 3% hydrogen peroxide in periodontal therapy may require reevaluation.

A modification of the connective tissue graft procedure for the treatment of type II and type III ridge deformities.

Various grafting procedures have been developed for reconstruction of partially edentulous ridge deformities prior to prosthetic rehabilitation. The majority of these procedures have been applicable to reconstruction of Type I (buccolingual) ridge deformities. Type II and Type III defects present a more difficult challenge because of the need for apicocoronal augmentation and replacement of greater volumes of lost tissue. The onlay and subepithelial connective tissue grafts have been predominately used for the treatment of these type of defects, however, each procedure presents certain limitations. This report describes a simple modification of the connective tissue graft that enhances its ability to augment tissue for Type II and Type III deformities. The technique is an effective and predictable procedure for advanced ridge deformities.

Demonstration of high-energy 2 omega (526.5 nm) operation on the National Ignition Facility Laser System.

A single beamline of the National Ignition Facility (NIF) has been operated at a wavelength of 526.5 nm (2 omega) by frequency converting the fundamental 1053 nm (1 omega) wavelength with an 18.2 mm thick type-I potassium dihydrogen phosphate (KDP) second-harmonic generator (SHG) crystal. Second-harmonic energies of up to 17.9 kJ were measured at the final optics focal plane with a conversion efficiency of 82%. For a similarly configured 192-beam NIF, this scales to a total 2 omega energy of 3.4 MJ full NIF equivalent (FNE).

National Ignition Facility laser performance status.

The National Ignition Facility (NIF) is the world's largest laser system. It contains a 192 beam neodymium glass laser that is designed to deliver 1.8 MJ at 500 TW at 351 nm in order to achieve energy gain (ignition) in a deuterium-tritium nuclear fusion target. To meet this goal, laser design criteria include the ability to generate pulses of up to 1.8 MJ total energy, with peak power of 500 TW and temporal pulse shapes spanning 2 orders of magnitude at the third harmonic (351 nm or 3omega) of the laser wavelength. The focal-spot fluence distribution of these pulses is carefully controlled, through a combination of special optics in the 1omega (1053 nm) portion of the laser (continuous phase plates), smoothing by spectral dispersion, and the overlapping of multiple beams with orthogonal polarization (polarization smoothing). We report performance qualification tests of the first eight beams of the NIF laser. Measurements are reported at both 1omega and 3omega, both with and without focal-spot conditioning. When scaled to full 192 beam operation, these results demonstrate, to the best of our knowledge for the first time, that the NIF will meet its laser performance design criteria, and that the NIF can simultaneously meet the temporal pulse shaping, focal-spot conditioning, and peak power requirements for two candidate indirect drive ignition designs.

Solvent regulation of oxygen affinity in hemoglobin. Sensitivity of bovine hemoglobin to chloride ions.

Under physiological conditions of pH (7.4) and chloride concentration (0.15 M), the oxygen affinity of bovine hemoglobin is substantially lower than that of human hemoglobin. Also, the Bohr effect is much more pronounced in bovine hemoglobin. Numerical simulations indicate that both phenomena can be explained by a larger preferential binding of chloride ions to deoxyhemoglobin in the bovine system. Also, they show that the larger preferential binding may be produced by a decreased affinity of the anions for oxyhemoglobin, thereby stressing the potential relevance of the oxy conformation in regulating the functional properties of the protein. The conformation of the amino-terminal end of the beta subunits appears to regulate the interaction of hemoglobin with solvent components. The pronounced sensitivity of the oxygen affinity of bovine hemoglobin to chloride concentration and to pH suggests that in bovine species these are the modulators of oxygen transport in vivo.

The manager's role as coach and mentor.

By serving as mentors, managers can help employees expand their capabilities and improve their performance, but first a manager must create the proper climate and develop the specific skills needed for effective coaching.