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A ventricular-aortic blood pump was constructed for the functional replacement of the left heart. Hemodynamic experiments showed that the device was able to pump the total cardiac output in calves with a body weight under 85 kg. In these cases the myocardial oxygen consumption decreased to 40%. Laboratory findings in 5 longterm experiments revealed a complete adaptation of the body to the artificial organ up to 73 days.
This paper describes a novel method providing durable layering of heparin immobilized hydrogels on fabricated devices. The preparation method is based on photochemistry of a dithiocarbamate group that is dissociated into a highly reactive radical pair upon ultraviolet (UV) irradiation. By taking advantage of characteristics of the photo generated radicals, hydrogel formation and its fixation onto a substrate surface were attained. The immobilization of heparin onto poly(ethylene terephtalate) was demonstrated. First, a mixed aqueous solution containing a photoreactive water soluble poly(N,N-dimethylacrylamide-covinylbenzyl N,N-diethyldithiocarbamate) and heparin was coated on the substrate. Subsequent UV irradiation resulted in the simultaneous formation of a heparin immobilized hydrogel and its chemical fixation onto the substrate. No delamination was found after vigorous washing with water. Significant inhibition of platelet adhesion and markedly prolonged blood coagulation times were observed, which are apparently derived from the surface hydrogel, and from released and chemically fixed surface heparin. Thus, it is expected that the photochemical method developed here provides potent antithrombogenicity to artificial organs.
The Faculty of Medical Sciences (FMS), University of the West Indies, recognizes that ethics and law are not currently given adequate importance in the training of health professionals. FMS also recognizes the rapid advancement of technology, such as transplants, artificial organs, in vitro fertilization, life-sustaining equipment and euthanasia, as well as the ever-increasing prevalence of malpractice. Thus, two conferences were held to consider the implementation of ethics and law in the medical curriculum. The conferences recommended an increased input into the curriculum of ethics and law, and that this programme be taught and examined in all the medical years. The article discusses implementation strategies.
Although various work has been done in the field of implantable micro actuators such as artificial organs and micro surgery robots, a suitable electric power supply for these is yet to be developed. For this purpose a micro fabricated enzyme fuel cell was developed which uses glucose contained in the human body as a fuel. In order to obtain enough voltage each cell was formed as part of a serial array on a silicon wafer. Glucose solution enters the cells by a capillary effect. In this article fuel cells already developed using biocatalysts are described, and the future possibility of a micro fabricated enzyme battery is discussed.
Haemoincompatibility induced by contact with artificial materials is a major obstacle to further development of artificial organs and accounts for much of morbidity in circumstances when the blood is circulated through an extracorporeal system or a catheter is placed. Material's testing was performed using different models and a score system (0-60 scorepoints) was developed. Our models can characterize ex vivo haemocompatibility of different polymers. Flow characteristics and preanalytical effects (e.g. anticoagulants) may not be neglected.
In recent years studies forecasting the future such as Delphi expert surveys were carried out in various Western countries to make predictions on future developments in medicine and in the health care system. The answers draw a homogeneous picture: Cancer and dementia research as well as the development of materials for implantation and artificial organs are-in context of the demographic changes-of enormous relevance, whereas basic research receives less attention. Due to various technological developments in telecommunication and in diagnostics (sensors), sociomedical care at home is supported and will become more frequent.
Three rapid spectroscopic approaches for whole-organism fingerprinting-pyrolysis mass spectrometry (PyMS), Fourier transform infra-red spectroscopy (FT-IR) and dispersive Raman microscopy--were used to analyse a group of 59 clinical bacterial isolates associated with urinary tract infection. Direct visual analysis of these spectra was not possible, highlighting the need to use methods to reduce the dimensionality of these hyperspectral data. The unsupervised methods of discriminant function and hierarchical cluster analyses were employed to group these organisms based on their spectral fingerprints, but none produced wholly satisfactory groupings which were characteristic for each of the five bacterial types. In contrast, for PyMS and FT-IR, the artificial neural network (ANN) approaches exploiting multi-layer perceptrons or radial basis functions could be trained with representative spectra of the five bacterial groups so that isolates from clinical bacteriuria in an independent unseen test set could be correctly identified. Comparable ANNs trained with Raman spectra correctly identified some 80% of the same test set. PyMS and FT-IR have often been exploited within microbial systematics, but these are believed to be the first published data showing the ability of dispersive Raman microscopy to discriminate clinically significant intact bacterial species. These results demonstrate that modern analytical spectroscopies of high intrinsic dimensionality can provide rapid accurate microbial characterization techniques, but only when combined with appropriate chemometrics.
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The organization of higher plant genomes is poorly understood. These genomes are typified by their large size and extensive repetitive DNA component. To further our understanding of the composition and arrangement of genomic DNA sequences, we have performed a detailed analysis of a contiguous interval of 280 kb surrounding the Adh1 locus of maize. A series of overlapping lambda subclones was isolated, and individual fragments were characterized with respect to their genomic copy number. Cross-hybridization analyses were used to define a minimum of 37 repetitive DNA classes within the 280-kb interval. Hybridizations with highly repetitive DNAs cloned from other regions of the maize genome suggested that > 50% of all highly repetitive elements in maize are represented on this single yeast artificial chromosome. These repeated sequences were found in an organizational pattern not previously observed; individual repetitive elements are interspersed with one another in an apparently random fashion and are spatially separate from single copy number sequences. Extensive tandem arrays were not found. Sequences from one end of the 280-kb interval were used to isolate overlapping yeast artificial chromosome clones, representing the first step in a chromosome walk.
Sprinkling infiltration in a forested esker leading to artificial recharge of groundwater was studied in Southern Finland. Changes in dissolved organic carbon (DOC) and the molecular size distribution and chemical properties of the organic carbon were investigated during the infiltration process. Artificial groundwater was produced using sprinkling infiltration directly onto the forest floor. One result of lake water infiltration through the organic horizon and I m thick mineral soil layer was a slight net increase in the DOC concentrations from 9.4 mg/L in the infiltration water to 13.2 mg/ L in percolation water. This indicates that the forest soil represents a potential input of organic matter into infiltration water. However, the DOC concentrations decreased by 27-38% as the infiltration water percolated down through the unsaturated soil layer into the groundwater zone. At a distance of 1450 m from the infiltration area, the mean DOC concentration in the groundwater was below the recommended value for drinking water in Finland of 2.0 mg/L. There was a strong reduction in the concentrations of hydrophilic and hydrophobic acids, but only a slight decrease in hydrophilic neutral organic compounds during the infiltration process. The DOC in the production well consisted of low molecular size fractions. Larger molecular size fractions were removed effectively from the water during the infiltration process.
Autism is a developmental disorder with possibly multiple pathophysiologies. It has been theorized that cortical feature maps in individuals with autism are inadequate for forming abstract codes and representations. Cortical feature maps make it possible to classify stimuli, such as phonemes of speech, disregarding incidental detail. Hierarchies of such maps are instrumental in creating abstract codes and representations of objects and events. Self-Organizing Maps (SOMs) are artificial neural networks that offer insights into the development of cortical feature maps. Attentional impairment is prevalent in autism, but whether it is caused by attention-shift impairment or strong familiarity preference or negative response to novelty is a matter of debate. We model attention shift during self-organization by presenting a SOM with stimuli from two sources in four different modes, namely, novelty seeking (regarded as normal learning), attention-shift impairment (shifts are made with a low probability), familiarity preference (shifts made with a lower probability to the source that is the less familiar to the SOM of the two sources), and familiarity preference in conjunction with attention-shift impairment. The resulting feature maps from learning with novelty seeking and with attention-shift impairment are much the same except that learning with attention-shift impairment often yields maps with a somewhat better discrimination capacity than learning with novelty seeking. In contrast, the resulting maps from learning with strong familiarity preference are adapted to one of the sources at the expense of the other, and if one of the sources has a set of stimuli with smaller variability, the resulting maps are adapted to stimuli from that source. When familiarity preference is less pronounced, the resulting maps may become normal or fully restricted to one of the sources, and in that case, always the source with smaller variability if such a source is present. Such learning, in a system with many different maps, will result in very uneven capacities. Learning with familiarity preference in conjunction with attention-shift impairment surprisingly has higher probability for the development of normal maps than learning with familiarity preference alone.
OBJECTIVE: To determine differences in the identity and quantity of microbial flora from healthcare workers (HCWs) wearing artificial nails compared with control HCWs with native nails. DESIGN: Two separate studies were undertaken. In study 1, 12 HCWs who did not normally wear artificial nails wore polished artificial nails on their nondominant hand for 15 days. Identity and quantity of microflora were compared between the artificial nails and the polished native nails of the other hand. In study 2, the microbial flora of the nails of 30 HCWs who wore permanent acrylic artificial nails were compared with that of control HCWs who had native nails. In both studies, nail surfaces were swabbed and subungual debris was collected to obtain material for culture. Staphylococcus aureus, gram-negative bacilli, enterococci, and yeasts were considered to be potential pathogens. All organisms were identified and quantified. RESULTS: In study 1, potential pathogens were isolated from more samples obtained from artificial nails than native nails (92% vs. 62%; P<.001). Colonization of artificial nails increased over time; by day 15, 71% of cultures yielded a pathogen compared with 21% on day 1 (P=.004). A significantly greater quantity of organisms (expressed as mean log10 colony-forming units +/- standard deviation) was isolated from the subungual area than the nail surface; this was noted for both artificial (5.0+/-1.4 vs. 4.1+/-1.0; P<.001) and native nails (4.9+/-1.3 vs. 3.7+/-0.8; P<.001). More organisms were found on the surface of artificial nails than native nails (P=.008), but there were no differences noted in the quantities of organisms isolated from the subungual areas. In study 2, HCWs wearing artificial nails were more likely to have a pathogen isolated than controls (87% vs. 43%; P=.001). More HCWs with artificial nails had gram-negative bacilli (47% vs. 17%; P=.03) and yeasts (50% vs. 13%; P=.006) than control HCWs. However, the quantities of organisms isolated from HCWs wearing artificial nails and controls did not differ. CONCLUSIONS: Artificial fingernails were more likely to harbor pathogens, especially gram-negative bacilli and yeasts, than native nails. The longer artificial nails were worn, the more likely that a pathogen was isolated. Current recommendations restricting artificial fingernails in certain healthcare settings appear justified.
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The date on the distribution of the main radiologicaly important polutants of biosphera (90Sr, 137Cs, 239 + 240Pu, 238Pu, 241Am) over the molecular mass fractions of organic matter in the soil solutions of natural environments are presented. Molecular mass constitution and radionuclide content in the fractions are dependent on radionuclide nature and type of soil and change along the soil profile. The major portion of 238Pu, 239 + 240Pu and 241Am (72-98%) was bound with organic matter in the soil solutions. In the case of organic horizons, these radionuclides were selectively connected with the fractions of high molecular masses (MMw > or = 2000). Radiostrontium is present principally in the fraction of inorganic compounds (19-100%) and in the low molecular mass fraction of organic matter (MMw = 350-500). A selective interaction of 137Cs with organic matter of definite molecular masses was not observed. The radionuclide was found in the "organic" fractions of a wide range of molecular masses (MMw from 350-500 to > or = 18,000) (34-97%) as well as in the fraction of inorganic compounds. The data obtained can provide the theoretical basis for explanation of higher mobility of 90Sr in soil profiles compared to other radionuclides.
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Crystals have been observed in the liver of 4 children, submitted to a parenteral nutrition and or, continuous enteral nutrition. Those crystals appear to be birefringent with polarized light extra and intracellular in electron microscopy, they contain a large amount of calcium, phosphore and sulfur. They are thought to represent organic crystals precipitating within the bile ductules of the portal areas. The occurence of those organic crystals seems to be related to a lack of bile secretion due to the exclusion of kinetic and secretory activity of the stomach and the duodenum.