SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Deep-sea sediment samples were collected at a depth of 3,064 m in the Japan Sea. Microorganisms in the sediment sample were cultivated under several pressure conditions, and the high-pressure adapted microbes were isolated. Two of the isolates exhibited piezophilic growth profiles. This is the first report to show the presence of piezophiles in the Japan Sea.
The Sharing Health Care Initiative (SHCI) demonstration project, which aimed to improve management of chronic diseases, was implemented in four small remote communities in the Katherine region which are serviced by the Katherine West Health Board, a remote Aboriginal-community-controlled health organisation in the Northern Territory. We reviewed the project proposal, final report, evaluation reports and transitional funding proposal, and supplemented these with in-depth interviews with key individuals. We determined factors critical to the sustainability of the SHCI project in relation to context, community engagement, systems flexibility and adaptability, the availability and effect of information systems, and the human nature of health care and policy. The project had a significant impact on community awareness of chronic disease and an improvement in clinic processes. We found that a number of interrelated factors promoted sustainability, including: An implementation strategy sufficiently flexible to take account of local conditions; A high level of community engagement; Appropriate timeframes, timing and congruence between national policy and local readiness to implement a chronic disease project; Effective communication between participating organisations; Project champions (key individuals) in participating organisations; Effective use of monitoring and evaluation data; and Adequate and ongoing funding. The absence of a number of these factors, such as poor communication, inhibited sustainability. Other factors could both promote and inhibit. For example, the impact of key individuals was important, but could be idiosyncratic and have negative effects.
Numbers of intestinal goblet cells containing specific acid mucins were determined in male Sprague-Dawley rats receiving azoxymethane (total dose 90 mg kg-1) with or without jejunoileal bypass (JIB). Controls had injections of vehicle and sham bypass. Thirty weeks postoperatively colorectal length and crypt depth were increased by azoxymethane and further increased by JIB. JIB doubled the yield of intestinal tumours (P less than 0.01). Goblet cells containing sulphomucins normally predominated throughout the intestinal tract. Contents of sulphomucins and especially sialomucins were consistently higher in the small bowel and colon of rats receiving azoxymethane alone, but again the highest values were observed in animals with azoxymethane plus JIB. Both small-bowel bypass and azoxymethane stimulate adaptive growth of the colon and small bowel remaining in circuit. Goblet-cell hyperplasia is a feature of this response, and sialomucins are preferentially secreted by the adapting epithelium.
A new, versatile adapter for computed tomography-guided stereotaxis is presented. The instrument consists of a light aluminum frame, which by means of a nasion support and two ear plugs is fixed to the patient's head. Reproducibility of repeated fixations is very high. The adapter is fitted to most stereotactic frames and can be used in all adult patients. Comparison between computed tomography- and ventriculography-guided determinations of thalamic targets showed a mean difference of 0.6 and 0.7 mm for the x and y coordinates, respectively. The z coordinates seldom showed any measurable difference. We now perform all types of stereotactic neurosurgery (tumor biopsy, implantation of depth electrodes, thalamotomy, dentatotomy, cingulotomy, etc.) with computed tomography guidance only. The short-term results in a small number of patients have been at least as good as after conventional ventriculography-guided surgery. In addition to open stereotactic surgery, the adapter is also suitable for external stereotactic irradiation of intracranial targets with a linear accelerator.
The analysis of stereoelectroencephalographic (intracerebral recording) signals provides information on the electrical activity of brain structures implied in epileptic seizures. A simple nonparametric adaptive segmentation method, based on a physiologically relevant parameter, is presented and compared with three methods reported in the literature. The comparative frame allows us to objectively test methods for their performances on the same basis. Results show that the proposed method is robust with respect to the types of change studied and easier to conduct, even if it is less accurate about the estimation of instants of change than another method presented in this study. Signals are segmented throughout the duration of seizures without parameter readjustment and generate instants of change in accordance with those interactively delimited by the clinician.
A neural network theory of three-dimensional (3-D) vision, called FACADE theory, is described. The theory proposes a solution of the classical figure-ground problem for biological vision. It does so by suggesting how boundary representations and surface representations are formed within a boundary contour system (BCS) and a feature contour system (FCS). The BCS and FCS interact reciprocally to form 3-D boundary and surface representations that are mutually consistent. Their interactions generate 3-D percepts wherein occluding and occluded object parts are separated, completed, and grouped. The theory clarifies how preattentive processes of 3-D perception and figure-ground separation interact reciprocally with attentive processes of spatial localization, object recognition, and visual search. A new theory of stereopsis is proposed that predicts how cells sensitive to multiple spatial frequencies, disparities, and orientations are combined by context-sensitive filtering, competition, and cooperation to form coherent BCS boundary segmentations. Several factors contribute to figure-ground pop-out, including: boundary contrast between spatially contiguous boundaries, whether due to scenic differences in luminance, color, spatial frequency, or disparity; partially ordered interactions from larger spatial scales and disparities to smaller scales and disparities; and surface filling-in restricted to regions surrounded by a connected boundary. Phenomena such as 3-D pop-out from a 2-D picture, Da Vinci stereopsis, 3-D neon color spreading, completion of partially occluded objects, and figure-ground reversals are analyzed. The BCS and FCS subsystems model aspects of how the two parvocellular cortical processing streams that join the lateral geniculate nucleus to prestriate cortical area V4 interact to generate a multiplexed representation of Form-And-Color-And-DEpth, or FACADE, within area V4. Area V4 is suggested to support figure-ground separation and to interact with cortical mechanisms of spatial attention, attentive object learning, and visual search. Adaptive resonance theory (ART) mechanisms model aspects of how prestriate visual cortex interacts reciprocally with a visual object recognition system in inferotemporal (IT) cortex for purposes of attentive object learning and categorization. Object attention mechanisms of the What cortical processing stream through IT cortex are distinguished from spatial attention mechanisms of the Where cortical processing stream through parietal cortex. Parvocellular BCS and FCS signals interact with the model What stream. Parvocellular FCS and magnocellular motion BCS signals interact with the model Where stream.(ABSTRACT TRUNCATED AT 400 WORDS)
A short-segment intestinal graft is favorable to reduce the rate of rejection and the incidence of graft-versus-host disease in recipients of small intestine transplantation. To determine whether a jejunal or an ileal graft is preferable with respect to intestinal morphology and function, syngeneic two-step small intestinal transplantations were performed using male Lewis rats (RT1(1)). They were divided into two groups according to the small intestine donor site (group 1 received 10 cm of jejunum; group 2 received 10 cm of ileum). There was no significant difference in the survival rate or weight gain between the two groups. Nearly all the hematologic findings, serum nutritional parameters, and results of liver function tests were normal for both groups. The only difference was that the serum total bile acid level was significantly higher in group 2. Fifty weeks after transplantation, the graft mucosa showed normal architecture, with adaptive hyperplasia of villi and crypt noted through histological study. The villus height of group 1 was 595 +/- 64 microns (control, 452 +/- 67 microns); that of group 2 was 732 +/- 53 microns (control, 217 +/- 20 microns). The crypt depth of group 1 was 228 +/- 35 microns (control, 165 +/- 24 microns); that of group 2 was 320 +/- 19 microns (control, 102 +/- 19 microns). These compensatory changes were more pronounced in group 2. The authors conclude that, on the basis of long-term functional capacity, there was no significant difference between jejunal and ileal grafts, and that both segments were suitable for transplantation. However, the ileal graft was considered to be better with respect to morphological adaptation.
The Coping Inventory for Stressful Situations (CISS) is a 48-item self-report inventory designed to measure three basic coping styles: Task Oriented, Emotion Oriented, and Avoidance Oriented coping. The psychometric properties of this inventory are promising, but CISS scores have not yet been shown to reflect behavioral variation in response to stress. This study was designed as a first step toward this end by examining the relationship between self- and peer-report on the CISS. One hundred and sixty-three pairs of friends completed the CISS, a peer form of the CISS, and a friendship questionnaire. Positive but modest correlations were found for each construct. Higher correlations were obtained when comparing scores across forms completed by the same informant, indicating that examinees believe their friends cope as they do themselves. Actual friend similarity was apparent only on Avoidance Oriented coping. Neither depth of relationship nor item observability moderated peer-self agreement.
AIM: A computer-based approach to assess stereopsis for screening purposes is described. This approach is based on random-dot stereograms (RDS). METHOD: The TNO test is a common method to assess stereopsis based on red/green anaglyphs and the use of RDS. This technique was transferred to a computer-based platform. To investigate the validity of the computer-based approach, 25 subjects were tested with both the TNO test and the computer-based approach. RESULTS: With regard to the spectral emission of the monitor screen, accurate separation of red and green for RDS generation was not possible. However, adaptation of the RDS to the colour filters used permitted the best-possible separation. The resolution of the monitor required a viewing distance of 2 m. The results obtained showed no significant differences between the two methods. CONCLUSIONS: For the computer-based screening, RDS and anaglyphs can be employed. The influence of the spectral emission of the monitor screen and its resolution can be reduced by adapting the RDS colours to the filters used and modifying the viewing distance.
PURPOSE: To develop and validate a software program which automatically detects gaps of cylindrical fillings in bovine dentin by using an optical sensor (FRT MicroProf), evaluate 8 different adhesive systems with the defined parameters, and compare the results with that of SEM quantitative marginal analysis. MATERIALS AND METHODS: An optical measuring head with strong wavelength dependency on its focal length splits white light into its colors. The surface height can be measured from the wavelength of the reflected light (resolution: x/y 1 to 2 microm, z 10 nm). A profile of the surface is taken by scanning the measuring point radially from the center of the filling over the restoration margins. An algorithm detects gaps and calculates their depths and widths. Eight adhesive systems (AdheSE, Clearfil SE, Excite, iBond, Optibond Solo Plus, Prompt L-Pop, Touch and Bond, Xeno III) were applied in cylindrical cavities (n = 8, ø = 4 mm, depth 2.5 mm, C-factor 3.5) in bovine dentin together with Tetric Ceram. In the control group, no adhesive system was used. After 24 h of storage in distilled water at 37 degrees C, the surface was polished with 4000-grit abrasive paper, and then epoxy resin replicas were produced. The evaluation criteria were as follows: the percentage of continuous margin along the entire margin (SEM, 500X) and the percentage of gap-free profiles to total profiles (FRT MicroProf), the latter being evaluated by using 100, 300 and 1000 profiles per sample. Two groups (Touch and Bond, Optibond Solo Plus) with 16 samples were selected to evaluate reproducibility and the occurrence of voids adjacent to the restoration margins. For each adhesive, a paired t-test was applied to evaluate the differences between both test methods for each adhesive. A linear regression analysis procedure was used to evaluate the overall agreement between the two test methods. RESULTS: The mean deviation between three consecutive measurements was 2.75%. Ten percent of all profiles showed voids adjacent to the restoration margins; 92% of the voids were excluded by setting the threshold value of the gap width at 20 microm. In less than 1% of the profiles, the concurrent presence of gap and void resulted in the nondetection of gaps. It was found that 100 profiles per sample are sufficient to characterize a sample as compared to SEM analysis. Except for the control group, the paired t-test did not reveal any statistically significant difference between the two test methods for either adhesive (p < 0.05). Regression analysis for all 72 data points yielded R2 = 0.72 (p < 0.0001). CONCLUSION: The results of the quantitative marginal analysis by means of the FRT optical sensor are comparable to those obtained by SEM. The advantages of this method include (1) saving of operator time, (2) independence of operator's experience and bias, and (3) additional information about the gap width and depth.
BACKGROUND: Low-fat diets (LFD) are utilized frequently in patients with short bowel syndrome (SBS). The purpose of this study was to investigate the effects of LFD on intestinal adaptation, enterocyte proliferation, and enterocyte cell death in a rat model of SBS. METHODS: Adult male Sprague-Dawley rats were divided into 3 experimental groups: Sham-NC rats underwent bowel transection and reanastomosis and were fed normal chow (NC), SBS-NC rats underwent 75% small bowel resection and were fed NC, and SBS-rats were fed a low-fat diet (SBS-LFD). Parameters of intestinal adaptation, enterocyte proliferation, and enterocyte apoptosis were determined on day 14 after operation. RESULTS: SBS-NC rats showed a significant increase (v Sham-NC) in jejunal and ileal bowel and mucosal weight, mucosal DNA and protein, villus height, and crypt depth. A significant 67% increase in crypt cell proliferation rate and 265% increase in villus enterocyte apoptosis was seen in the ileum of SBS-NC rats compared with control animals (P <.05). SBS-LFD animals showed lower ileal mucosal weight (29%; P <.05), jejunal crypt depth (20%; P <.05), and ileal villus height (21%; P <.05). A significant decrease in villus apoptosis in jejunum (74%; P <.05) and ileum (67%; P <.05) and a decrease in cell proliferation in ileum (35%; P <.05) was seen also after exposure to LFD compared with SBS-NC. CONCLUSIONS: In a rat model of SBS, early LFD appears to inhibit parameters of intestinal adaptation. A possible mechanisms for this effect may be decreased cell proliferation. Decreased enterocyte loss via apoptosis, found in this study, may reflect a reduced number of enterocyte.
This study analyzes the structure and mechanical properties of the trachea of the striped dolphin Stenella coeruleoalba, one of the most common cetacean species. The cetacean trachea is made up of closed or semiclosed cartilaginous rings without a paries membranaceus. Our results indicate that the inner lining of the trachea contains erectile tissue in which several venous lacunae permeate the mucosa. We also observed and described the presence of peripheral neurons containing nitric oxide along the rim of the venous lacunae. Data obtained from compression and tensile tests and comparison with the pig and goat tracheas indicate a higher stiffness and a different, higher breaking point for the dolphin trachea. On the whole, our data suggest that the trachea of the striped dolphin possesses structural properties that allow rapid filling with blood, possibly in relation to dive activities, and also allow modifications due to increased pressure and immediate return to the original shape without risks of permanent bending or rupture, as would happen in a terrestrial mammal. As the organ undergoes intense pressure difference during descent to optimal foraging depth and subsequent rapid ascent to surface, especially in deep dives of hundreds of meters, the specific structural and biomechanical peculiarities of the trachea of the striped dolphin may represent an evolutionary adaptation to life in the water and to diving.
Slowly adapting pulmonary stretch receptors (SARs) participate in numerous respiratory reflexes, including the Hering-Breuer lung inflation reflex (HBR), and reflex control of respiratory rate and depth. In addition, SAR discharge may modulate airway tone. We studied the effect of acrylamide neuropathy, which causes reversible dysfunction of SARs and their myelinated vagal afferents, on the breathing pattern, HBR and airway tone in conscious dogs. As neuropathy evolved, breathing became slow and deep, and both the apnoeic and bronchodilatory responses to lung inflation were markedly reduced, findings consistent with SAR dysfunction. Recovery of clinical neuropathy and respiratory reflexes followed acrylamide withdrawal. Despite the obvious abnormalities of SAR-mediated reflexes in acrylamide-affected dogs, airway tone remained normal and sinus arrhythmia prominent in the presence of neuropathy, suggesting that small diameter vagomotor efferents are relatively resistant to acrylamide. Acrylamide neuropathy provides a useful preparation for the study of vagomotor function in animals in which feedback from myelinated pulmonary afferents is attenuated.
In photosynthetic membranes of cyanobacteria, algae, and higher plants, photosystem I (PSI) mediates light-driven transmembrane electron transfer from plastocyanin or cytochrome c6 to the ferredoxin-NADP complex. The oxidoreductase function of PSI is sensitized by a reversible photooxidation of primary electron donor P700, which launches a multistep electron transfer via a series of redox cofactors of the reaction center (RC). The excitation energy for the functioning of the primary electron donor in the RC is delivered via the chlorophyll core antenna in the complex with peripheral light-harvesting antennas. Supermolecular complexes of the PSI acquire remarkably different structural forms of the peripheral light-harvesting antenna complexes, including distinct pigment types and organizational principles. The PSI core antenna, being the main functional unit of the supercomplexes, provides an increased functional connectivity in the chlorophyll antenna network due to dense pigment packing resulting in a fast spread of the excitation among the neighbors. Functional connectivity within the network as well as the spectral overlap of antenna pigments allows equilibration of the excitation energy in the depth of the whole membrane within picoseconds and loss-free delivery of the excitation to primary donor P700 within 20-40 ps. Low-light-adapted cyanobacteria under iron-deficiency conditions extend this capacity via assembly of efficiently energy coupled rings of CP43-like complexes around the PSI trimers. In green algae and higher plants, less efficient energy coupling in the eukaryotic PSI-LHCI supercomplexes is probably a result of the structural adaptation of the Chl a/b binding LHCI peripheral antenna that not only extends the absorption cross section of the PSI core but participates in regulation of excitation flows between the two photosystems as well as in photoprotection.
H2S is produced as a main end-product of anaerobic mineralization in anoxic, sulphate-rich environments by a diverse population of sulphate-reducing bacteria. The sulphate reducers can carry out an almost complete oxidation of detrital organic matter to CO2. The H2S consequently becomes an important electron carrier from the anoxic to the oxic world. Thiobacilli and other colourless sulphur bacteria have the potential to oxidize the H2S at the oxic-anoxic interface in sediments or stratified waters, but their role is still poorly understood. A comparison of sulphide oxidation processes in the chemoclines of the Black Sea, the Solar Lake and in A beggiatoa mat indicated that depth scales and retention times of coexisting O2 and H2S regulate the bacterial involvement in the sulphide oxidation. The H2S specialists, Beggiatoa and Thiovulum, are optimally adapted to compete with the autocatalytic oxidation of H2S by O2. Microelectrode measurements show retention times of O2-H2S in the bacterial mats or veils of less than 1 s. In photic chemoclines of stratified waters or sulfureta, the phototrophic sulphur bacteria or cyanobacteria interact with the sulphide oxidation at the O2-H2S interface. Short cycles between H2S and intermediate oxidation products, So or S2O2 3-, are created. The bacteria of the sulfuretum are highly adapted to the diurnal rhythm of light, O2 and H2S.
Synthetic aperture focusing using a virtual source was used previously to increase the penetration and to extend the depth of focus in high-frequency ultrasonic imaging. However, the performance of synthetic aperture focusing is limited by its high sidelobes. In this paper, an adaptive weighting technique based on a focusing-quality index is introduced to suppress the sidelobes. The focusing-quality index is derived from the spatial spectrum of the scan-line data along the mechanical scan direction (i.e., the synthetic aperture direction) after focusing delays relative to the virtual source have been applied. The proposed technique is of particular value in high-frequency ultrasound in which dynamic focusing using array transducers is not yet possible. Experimental ultrasound data from a 50-MHz imaging system with a single-crystal transducer (f-number = 2) are used to demonstrate the efficacy of the proposed technique on both wire targets and speckle-generating objects. An in vivo experiment also is performed on a mouse to further demonstrate the effectiveness. Both 50-MHz fundamental imaging and 50-MHz tissue harmonic imaging are tested. The results clearly demonstrate the effectiveness in sidelobe reduction and background-noise suppression for both imaging modes. The principles, experimental results, and implementation issues of the new technique are described in this paper.
Methanogenesis in cold marine sediments is a globally important process leading to methane hydrate deposits, cold seeps, physical instability of sediment, and atmospheric methane emissions. We employed a multidisciplinary approach that combined culture-dependent and -independent analyses with geochemical measurements in the sediments of Skan Bay, Alaska (53 degrees N, 167 degrees W), to investigate methanogenesis there. Cultivation-independent analyses of the archaeal community revealed that uncultivated microbes of the kingdoms Euryarchaeota and Crenarchaeota are present at Skan Bay and that methanogens constituted a small proportion of the archaeal community. Methanogens were cultivated from depths of 0 to 60 cm in the sediments, and several strains related to the orders Methanomicrobiales and Methanosarcinales were isolated. Isolates were psychrotolerant marine-adapted strains and included an aceticlastic methanogen, strain AK-6, as well as three strains of CO(2)-reducing methanogens: AK-3, AK7, and AK-8. The phylogenetic positions and physiological characteristics of these strains are described. We propose a new species, Methanogenium boonei, with strain AK-7 as the type strain.
The magnitude of gut adaptation is a decisive factor in determining whether patients are able to live independent of parenteral nutrition after massive small bowel loss. We previously established that the cyclin-dependent kinase inhibitor (CDKI) p21(waf1/cip1) is necessary for enterocyte proliferation and a normal adaptation response. In the present study, we have further elucidated the role of this CDKI in the context of p27(kip1), another member of the Cip/Kip CDKI family. Small bowel resections (SBRs) or sham operations were performed in control (C57/BL6), p21(waf1/cip1)-null, p27(kip1)-null, and p21(waf1/cip1)/p27(kip1) double-null mice. Morphological (villus height/crypt depth) alterations in the mucosa, the kinetics of enterocyte turnover (rates of enterocyte proliferation and apoptosis), and the protein expression of various cell cycle-regulatory proteins were recorded at various postoperative times. Enterocyte compartment-specific mRNA expression was investigated using laser capture microdissection. Resection-induced adaptation in control mice coincided with increased protein expression of p21(waf1/cip1) and decreased p27(kip1) within 3 days postoperatively. Identical changes in mRNA expression were detected in crypt but not in villus enterocytes. Adaptation occurred normally in control and p27(kip1)-null mice; however, mice deficient in both p21(waf1/cip1) and p27(kip1) failed to increase baseline rates of enterocyte proliferation and adaptation. The expression of p21(waf1/cip1) protein and mRNA in the proliferative crypt compartment is necessary for resection-induced enterocyte proliferation and adaptation. The finding that deficient expression of p27(kip1) does not affect adaptation suggests that these similar CDKI family members display distinctive cellular functions during the complex process of intestinal adaptation.