An in-depth look at pressure sores using monolithic silicon pressure sensors

Three-dimensional scalar pressure distributions were measured in solid tissue near bony prominences in vitro in meat and in vivo in pigs using silicon pressure sensors. Data are in accord with previous theoretical models and indicate that pressure is three to five times higher internally near a bony prominence than it is at the skin over the prominence. Pressure sores are thus thought to begin internally; by the time they are evident at the skin, the sore has worked its way completely from bone to skin. This conclusion is in accord with previous clinical data. Future measurement of local vector forces is needed to fully characterize the force distribution in vivo.     

A multiple chemostat system for consortia studies on microbially influenced corrosion

A multiple chemostat system has been developed in which metal specimens can be exposed to a consortium of bacteria. The system comprises a single test chemostat containing the test specimen operated at a high dilution rate to facilitate the wash out of planktonic bacteria, selecting for attached or biofilm growth. This chemostat is fed at a steady low rate by a number of separate chemostats each of which contains a pure axenic culture of one member of the consortium being tested. This system has the advantage of providing a continual inoculum of the test species to the test specimen allowing both aerobic and anaerobic bacteria to be grown in the same system. Constant levels of three bacterial types were maintained in the system: Pseudomonas aeruginosa, Thiobacillus ferrooxidans and Desulfovibrio vulgaris. Exposure of 316L stainless steel electrodes to this system resulted in increased corrosion of coupons exposed biotically, as compared to those exposed abiotically. A current monitoring technique and electrochemical impedance spectroscopy were used to evaluate effects of bacteria on metallic corrosion.     

Colloquium on scientific authorship: rights and responsibilities

The Colloquium on Scientific Authorship was held at the National Institutes of Health (NIH) at a time of extraordinary scrutiny by the public of the ethics of scientists, as represented by intense interest of the press and the Congress of the United States. Indeed, several regulations dealing with scientific misconduct have been proposed during the last year in the Federal Register, and new legislation has been proposed in the Congress. As a result of these concerns, conferences have been organized by the Institute of Medicine, the American Association for the Advancement of Science/American Bar Association, the Council of Biology Editors, and other groups. The colloquium at NIH, which was held May 31, 1988, and sponsored by the Intramural Scientists, focused on publication practices, especially multiple authorship, as contributing to perceived difficulties. The participants suggested various changes in conventions related to authorship that might help prevent future problems.     

Production of DON-related trichothecenes byFusarium graminearum Schw from Krasnodarski krai of the USSR

34Fusarium graminearum Schw isolates produced 4-deoxynivalenol to form significant amounts of 4, 7 — dideoxynivalenol and lesser amounts of 4 — deoxynivalenol monoacetates on grain substratesin vitro. This is the first report on the capability a large group of naturally occurring isolates to produce 4,7-dideoxynivalenol. The average levels of 4,7-dideoxynivalenol on rice, corn, barley, and wheat as a substrate were respectively 26.8, 14.0, 12.8, and 10.5% of the level of 4-deoxynivalenol. 4, 7 — dideoxynivalenol was present in all examined naturally contaminated wheat kernel samples at levels of 1.7 to 7.9% of the level of 4-deoxynivalenol. These findings suggest that more attention should be given to the occurrence of 4,7-dideoxynivalenol in cereals.     

Variation in the ribosomal internal transcribed spacers (ITS1 and ITS2) among eight taxa of the Mimulus guttatus species complex

The internal transcribed spacer region (ITS1 and ITS2) of the 18S-25S nuclear ribosomal DNA sequence and the intervening 5.8S region were sequenced from three individuals in each of eight taxa of the Mimulus guttatus species complex. Three discrete variants, or "types," of ITS sequences were found, among which 30%-40% of sites differed, compared with 1%-2% within types. Dot plots indicate that these types were not related by conspicuous rearrangements or inversions. More than one ITS type was often found in the same taxon, and two of three ITS types span species boundaries, indicating their presence prior to speciation. These ITS sequences showed essentially no positional homology with the nearest sequenced relative, tomato. In contrast, the 5.8S region was relatively unvaried, with 8 of 162 sites varied in the sample among all eight taxa. The phylogeny inferred by the most common ITS sequence type, rooted by the two other ITS types, agreed with isozymes in showing the distinctness of M. nudatus, M. laciniatus, and M. tilingii from the other five taxa.      

CYTOCHROME P450 1A1 EXPRESSION IN CETACEAN INTEGUMENT: IMPLICATIONS FOR DETECTING CONTAMINANT EXPOSURE AND EFFECTS

Contaminant related health risks to marine mammals are typically inferred from the levels of contaminants measured in blubber. Such measurements alone are insufficient to indicate the likelihood of biological effects from contaminant exposure, especially for contaminants that do not bioaccumulate. Cytochrome P450 1A1 (CYP1A1) in mammals is induced by, and involved in, the metabolism of planar halogenated aromatic hydrocarbons and polycyclic aromatic hydrocarbons, chemicals of concern in aquatic systems. CYP1A induction is a molecular response to exposure to these inducers in many vertebrates. Using immunohistochemistry, we semiquantitatively measured CYP1A1 expression in integument (epidermis and blubber) collected by biopsy or at necropsy from 17 species of cetaceans. CYP1A1 expression was detected in all species and, in some cases, varied both within and between species. CYP1A1 expression in mysticetes was comparable to that in odontocetes. Assessing how the differences in contaminant burdens, life history parameters, and physiological condition between individuals, populations, or species affect CYP1A1 expression in cetacean integument is essential to the interpretation of this induction as a biomarker of exposure to and effects of contaminants. Detection of CYP1A1 expression in integument samples offers a relatively simple, non-lethal technique to study biological changes associated with contaminant exposure in cetaceans.