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PubMed2002

Effect of epidermal growth factor on intestinal adaptation after allogeneic small bowel transplantation in rats.

We reported that epidermal growth factor (EGF) stimulated graft adaptation in a rat model of syngeneic small bowel transplantation. However, graft rejection is a severe problem with clinical small bowel transplantation, because small intestinal wall contains large amounts of lymphoid tissue. Studies were performed to investigate the effect of EGF on allogeneic graft adaptation after small bowel transplantation in rats treated with an immunosuppressant FK506. The transplanted animals received intraperitoneally EGF or saline (untreated) after surgery and were examined for analysis one week later. EGF-treated group markedly enhanced the water absorption and induction of sodium glucose cotransporter (SGLTI) as compared with EGF-untreated group. EGF-treated group also increased the mucosal crypt depth and its cell proliferating rate, although there was no significant difference in the mucosal villus height between the two groups. These results indicate that EGF accelerates intestinal allograft adaptation in part by the recovery of mucosal structure and function after small bowel transplantation in rats. EGF may have relevance to promote graft function in clinical small intestinal transplantation.

Adaptation, Physiological↗

PubMed1990

Adaptiveness of tunnel system features in subterranean mammal burrows.

Most moles and mole rats spend their lifetimes within the confines of tunnel walls, constructing, maintaining, and modifying burrow system structure in response to changing external circumstances and changing internal needs. Thus, anatomy, physiology, behavior, and distribution are all greatly affected by the burrow environment, with temperature, humidity, gas concentrations, living space, availability of food and mating partners, and protection from flooding and predation all being influenced by burrow architecture. Regrettably, the burrow structure of almost all subterranean mammals is unknown, or known only from several incomplete excavations. Moreover, existing data is often vague without any mention of particular structures or surrounding habitat, which makes the placing of burrow structure in an adaptive perspective difficult. Reasons for these short-comings are understandable: excavations require laborious excavation which can extend for hundreds of meters, reaching depths in excess of a meter; it is often difficult to remove the occupant prior to excavation which avoids modification of the system by the animal during excavation; particular types of subterranean mammals are limited in distribution to particular continents so that the literature is often localized and a global perspective difficult to obtain; and there is no standardization of terms relating to burrow structure, making intergroup comparison confusing. This paper addresses the above difficulties and encourages further investigation in this central area of study by making obvious the paucity of information for most subterranean mammals, presenting a synopsis of known burrow structures of major groups which will make particular gaps in our knowledge evident, providing a bibliography of major papers on burrow structure with coverage of most moles and mole rats, establishing a checklist of burrow features to better analyze future excavations and facilitate intergroup comparison, and lastly, to indicate possible adaptive significance of various burrow features to promote further observation, speculation and experimentation.

Adaptation, Biological↗

PubMed1988

Substance P-like immunoreactive amacrine cells in the cat retina.

Substance P-like immunoreactivity was localized by immunocytochemical techniques to two subpopulations of amacrine cells in the cat retina. One cell was a unistratified amacrine with processes ramifying within stratum 4 of the inner plexiform layer. The other cell type was a bistratified cell with processes in both stratum 1 (s1) and stratum 4 (s4). Both cell types were seen with their somas displaced to the ganglion cell layer as well as in the conventional amacrine location in the inner nuclear layer. Substance P cells were present in the greatest density within the area centralis and decreased in number toward the periphery. The ratio of amacrine to displaced amacrine cells also decreased peripherally. However, the coverage by immunoreactive fibers in s4 remained three times that seen in s1. Computer-assisted analysis confirmed the location of substance P-containing processes at 5-15% (s1) and 50-70% (s4) depth levels in the inner plexiform layer. A comparison of substance P-like immunoreactivity in light- and dark-adapted cat retinas showed no apparent differences in the distribution of immunoreactivity due to lighting conditions.

Animals↗

PubMed1979

Computed tomography evaluation of fatty tumors of the somatic soft tissues: clinical utility and radiologic-pathologic correlation.

The role of computed tomography (CT) in the evaluation of fatty tumors of the somatic soft tissues was investigated. Six surgically proven cases of fatty tumors were studied preoperatively by CT and standard radiographic means--conventional radiographs, xeroradiography, and angiography. Our case material included a simple lipoma, two infiltrative lipomas, an angiolipoma, and two liposarcomas. The radiologic-pathologic correlation was evaluated with respect to the various imaging modalities. The unique tissue characteristics of fatty tumors makes them particularly adaptable to CT scanning. In addition to its ability to define accurately tissue densities, the facility of CT in depicting depth, size, and extent of the lesion in the axial plane was found to be most useful in the preoperative evaluation of our case material.

Adipose Tissue↗

PubMed2006

A balanced evaluation perspective: picture archiving and communication system impacts on hospital workflow.

Around the world, hospitals are faced with both budget and regulatory pressures, forcing them to re-examine the way clinical practice is carried out. Proposed technologies that provide workflow enhancements include Picture Archiving and Communications Systems (PACS); however, is PACS really effective in improving hospital workflow and the flow onto patient care, and how should this be evaluated? An acknowledged and successful approach for organizational evaluation is the Balanced Scorecard (BSC), providing the fundamental features for assessing organizations from various perspectives. In this research, the impact of PACS on the workflow of a large public hospital in Melbourne, Australia, is examined using an adapted version of the BSC. Empirically, this model was applied as an evaluation instrument through a series of in-depth interviews with PACS users. Results show that PACS did improve hospital workflow considerably and that the organizational alignment of PACS in hospitals is an important critical success factor.

Efficiency, Organizational↗

PubMed1998

Current educational reforms in nursing in the United Kingdom and their impact on the role of nursing lecturers in practice: a case study approach.

This paper explores major developments in nurse education in the UK in the last 5 years and examines their impact on the role of nursing lecturers in practice. It builds upon the findings of an earlier study that described significant changes in the UK in the role and work of nurse teachers resulting from Project 2000 initiatives. Empirical data were collected over a 2.5-year period, through observations of student-teacher interaction and in-depth interviews with experienced nurse teachers and senior health professionals (n = 41). A case study approach using qualitative techniques was adapted for the study. The results of the study showed that, in the light of current educational reforms, nursing lecturers were expected to maintain closer links with the service sector and spend more time on clinical teaching and learner contact. Also considered important was the need for nursing lecturers to support clinical staff in creating an effective learning environment. Using the findings of the study, the author has mapped what was perceived to be the development of an effective model for the role of nursing lecturers in practice: a model that reflects the expected changes to a higher educational environment.

Clinical Competence↗

PubMed1992

Effects of flicker modulation depth on the detection of changes in target location.

Response times to a change in location of a small, low contrast target in a uniform flickering field were investigated under a range of flicker modulation depths. Increasing depth of modulation gave an increased response time for modulation depths from 0% (no flicker, to approx. 35%. Further increases in modulation depth had only a marginal effect on response time. It is shown that this effect is not due to flicker adaptation. The functional form of the modulation dependence is qualitatively similar to that reported by Badcock and Smith (1989, Vision Research, 29, 803-808), but shows a large difference in the modulation at which a levelling of performance occurred. It is shown that this difference is consistent with the presence of a third temporal filter, as proposed by Mandler and Makous (1984, Vision Research, 24, 1881-1887).

Adult↗

PubMedDate not supplied

Design of computer-generated hologram with ring focus for nonmechanical corneal trephination with Er:YAG laser in penetrating keratoplasty.

PURPOSE: To calculate a beam-shaping optical element for homogeneous intensity distribution within a focal ring to be used in nonmechanical trephination with the Er:YAG laser in penetrating keratoplasty instead of a spot guiding device. METHODS: The phase distribution behind a holographic optical element (HOE) k psi(u) can be described by the addition of the hologram phase phiH(u) to the beam phase phiE(u): k psi(u) = phiH(u) + phiE(u), k = 2pi/lambda, where u denotes the coordinates inside the hologram aperture, k an integer, and lambda the laser wavelength. To avoid discontinuous wavefronts leading to speckle noise, a smooth phase function is necessary. After transforming the hologram aperture coordinates into the focal plane x in a focal distance f, psi can be retrieved from the slope equation: inverted delta psi(u) = x(u) - u/f. RESULTS: Creating a ring focus can be reduced to an essentially one-dimensional problem by separation of variables due to the symmetry condition. We calculated a computer-generated eight-level phase-only HOE with 4096 x 4096 pixels from a Gaussian-distributed 2.94 Er:YAG laser spot with a beam diameter of 10 mm and a focal distance of 100 mm. Thereby, a ring focus with an inner/outer radius of 7/8 mm can be created. To avoid Poisson's spo, the symmetry of the problem was broken by circular modulation of the phase leading to a spiral-like structure. The calculated efficiency of the HOE relating the energy within the ring to the total energy was 91%. CONCLUSION: With an HOE it is possible to redistribute the energy along the desired focal ring. The HOE design can be adapted to the intensity distribution of the impinging laser beam with its characteristic aperture shape. A circular homogeneous corneal trephination depth is possible, because the energy fluctuation from pulse to pulse does not locally affect the ablation process. A ring focus for the Er:YAG laser has the potential to render superfluous a manual beam control via micromanipulator and to allow a more rapid and more regular corneal trephination along aperture masks.

Cornea↗

PubMed2006

When family enters the picture: the model of cultural negotiation and gendered experiences of Japanese academic sojourners in the United States.

A grounded-theory study aimed at reconceptualizing cultural adaptation processes from gender role and family/couple perspectives while critically drawing from acculturation and culture and self literatures. In-depth interviews with 34 Japanese academic sojourners (international students, scholars) and their spouses (a total of 50 interviews with select longitudinal interviews) were conducted. The author earlier developed the Model of Cultural Negotiation (2001; 2006) capturing uneven and cyclical processes of dealing with multiple cultural contexts. The current study further develops more tailored versions of this model, Family-Based (Couple-Based) Cultural Negotiation and Individual-Based Cultural Negotiation, highlighting the impacts of family/couple and gender roles, especially for female spouses. These conceptualizations afford a sophisticated understanding of the processes of culture.

Acculturation↗

PubMed1993

Spectral motion produces an auditory after-effect.

Distortions of perception following prolonged exposure to an unvarying sensory stimulus have been observed since at least the third century BC. The motion after-effect is a familiar experience in which, after a few minutes of viewing objects moving in a single direction, a stationary object appears to move in the opposite direction. Similar after-effects have been observed for many visual stimuli, including tilted lines, colours, stereoscopic depth, curvature, spatial frequency, contrast, rotation and motion in depth. In contrast to the rich variety of visual after-effects reported since the 1960s, reports of analogous auditory adaptation effects only appeared in the 1970s, but have continued since then. Some effects of sound source spatial movement perception after adaptation to a spatially moving sound source have been reported. Here we report an auditory perceptual after-effect analogous to the visual motion after-effect, which is caused by adaptation to auditory spectral (frequency) motion. After a few minutes of listening to a simple spectral pattern moving upwards or downwards in frequency space, the same pattern sounds as though it is drifting in the opposite direction when it is stationary. The effect shows binaural transfer, implying that it is generated at the level after binaural interaction. After-effects produced by the motion of spectral peaks are independent of those produced by spectral notches, suggesting separate processing channels for spectral peaks and notches.

Auditory Perception↗

PubMed1988

Dynamics of skate horizontal cells.

The all-rod retina of the skate (Raja erinacea or R. oscellata) is known to have the remarkable capability of responding to incremental flashes superimposed on background intensities that initially block all light-evoked responses and are well above the level at which rods saturate in mixed rod/cone retinas. To examine further the unusual properties of the skate visual system, we have analyzed responses of their horizontal cells to intensity-modulated step, sinusoidal, and white-noise stimuli. We found that during exposures to mean intensities bright enough to block responses to incremental stimuli, decremental stimuli were also initially blocked. Thereafter, the horizontal cells underwent a slow recovery phase during which there was marked nonlinearity in their response properties. The cell first (within 2-3 min) responded to decrements in intensity and later (after greater than 10 min) became responsive to incremental stimuli. After adaptation to a steady state, however, the responses to intensity modulation were nearly linear over a broad range of modulation depths even at the brightest mean levels of illumination. Indeed, examination of the steady-state responses over a 5-log-unit range of mean intensities revealed that the amplitude of the white noise-evoked responses depended solely on contrast, and was independent of the retinal irradiance as the latter was increased from 0.02 to 20 muW/cm2; i.e., contrast sensitivity remained unchanged over this 1,000-fold increase in mean irradiance. A decrement from the mean as brief as 2 s, however, disturbed the steady state. Another unexpected finding in this all-rod retina concerns surround-enhancement, a phenomenon observed previously for cone-mediated responses of horizontal cells in the retinas of turtle and catfish. While exposure to annular illumination induced response compression and a pronounced sensitivity loss in response to incremental light flashes delivered to the dark central region, the cell's sensitivity showed a significant increase when tested with a white noise or sinusoidally modulated central spot. Unlike horizontal cells in other retinas studied thus far, however, response dynamics remained unchanged. Responses evoked either by a small spot (0.25-mm diam) or by a large field light covering the entire retina were almost identical in time course. This is in contrast with past findings from cone-driven horizontal cells whose response waveform (dynamics) was dependent upon the size of the retinal area stimulated.

Animals↗

PubMed2004

Changing professional practice in tuberculosis care: an educational intervention.

AIM: This paper describes the development and implementation of an experiential, participatory in-service education programme focusing on patient-centeredness, problem-solving and critical reflection for primary providers delivering care to tuberculosis patients in South Africa. BACKGROUND: Tuberculosis is a major contributor to the disease burden in developing countries. In South Africa, approximately 90% of tuberculosis patients are managed by nurses at the primary level. Despite efforts to improve quality of care for these patients, many fail to complete their treatment as prescribed. Poor rapport between health care providers and patients with tuberculosis is a major reason for non-adherence to treatment. Methods of improving the quality of care delivery and communication between health care providers and patients with tuberculosis is therefore a priority. DISCUSSION: The paper outlines the stages of developing and implementing the education programme and reflects on this process. Data is drawn from an in-depth qualitative evaluation of the delivery and impacts of the intervention. The approach was acceptable to health care providers and adaptable to the needs of specific clinics. Participants evaluated the educational intervention positively, noting that it facilitated critical reflection on their work; encouraged problem-solving; and heightened their awareness of communication with patients and with colleagues. However, important structural barriers to practice change were identified, including conditions of service, relations with colleagues and support from management. CONCLUSIONS: Experiential, participatory in-service education can be implemented on a large scale in primary care settings. However, the process is resource intensive and the impacts of such education may be limited by barriers at other levels of the health system.

Adolescent↗

PubMed2003

Experimental studies of applications of time-reversal acoustics to noncoherent underwater communications.

The most difficult problem in shallow underwater acoustic communications is considered to be the time-varying multipath propagation because it impacts negatively on data rates. At high data rates the intersymbol interference requires adaptive algorithms on the receiver side that lead to computationally intensive and complex signal processing. A novel technique called time-reversal acoustics (TRA) can environmentally adapt the acoustic propagation effects of a complex medium in order to focus energy at a particular target range and depth. Using TRA, the multipath structure is reduced because all the propagation paths add coherently at the intended target location. This property of time-reversal acoustics suggests a potential application in the field of noncoherent acoustic communications. This work presents results of a tank scale experiment using an algorithm for rapid transmission of binary data in a complex underwater environment with the TRA approach. A simple 15-symbol code provides an example of the simplicity and feasibility of the approach. Covert coding due to the inherent scrambling induced by the environment at points other than the intended receiver is also investigated. The experiments described suggest a high potential in data rate for the time-reversal approach in underwater acoustic communications while keeping the computational complexity low.

Journal Article↗

PubMed2005

Microbial diversity in coastal subsurface sediments: a cultivation approach using various electron acceptors and substrate gradients.

Microbial communities in coastal subsurface sediments are scarcely investigated and have escaped attention so far. But since they are likely to play an important role in biogeochemical cycles, knowledge of their composition and ecological adaptations is important. Microbial communities in tidal sediments were investigated along the geochemical gradients from the surface down to a depth of 5.5 m. Most-probable-number (MPN) series were prepared with a variety of different carbon substrates, each at a low concentration, in combination with different electron acceptors such as iron and manganese oxides. These achieved remarkably high cultivation efficiencies (up to 23% of the total cell counts) along the upper 200 cm. In the deeper sediment layers, MPN counts dropped significantly. Parallel to the liquid enrichment cultures in the MPN series, gradient cultures with embedded sediment subcores were prepared as an additional enrichment approach. In total, 112 pure cultures were isolated; they could be grouped into 53 different operational taxonomic units (OTU). The isolates belonged to the Proteobacteria, "Bacteroidetes," "Fusobacteria," Actinobacteria, and "Firmicutes." Each cultivation approach yielded a specific set of isolates that in general were restricted to this single isolation procedure. Analysis of the enrichment cultures by PCR and denaturing gradient gel electrophoresis revealed an even higher diversity in the primary enrichments that was only partially reflected by the culture collection. The majority of the isolates grew well under anoxic conditions, by fermentation, or by anaerobic respiration with nitrate, sulfate, ferrihydrite, or manganese oxides as electron acceptors.

Actinobacteria↗

PubMed1997

A review of the microcirculation of adipose tissue: anatomic, metabolic, and angiogenic perspectives.

Adipose tissue microcirculation is unique within the vascular system because of a capacity for this tissue to grow throughout most of adult life. A review of the microcirculation of adipose tissue has included a historical review of the early studies, which served as a foundation for later investigations on this topic, including basic hemodynamic measurements in mammalian adipose tissue. The various methods for measuring blood flow in white and brown adipose tissue are discussed with respect to studies of transport of substrates involved in adipose tissue metabolism. The role of innervation and vascular adrenergic receptors and the effects of diet and exercise on adipose tissue blood flow are also included. An in-depth analysis of the development of adipose tissue microvasculature indicates that angiogenesis often precedes adipogenesis. The clinical effects of hemodynamic adaptations to adipose tissue expansion are discussed in view of an epidemic increase in the prevalence of obesity and its co-morbidities. The recent discovery of sites of nuclear regulation of adipocyte differentiation, together with the identification of growth factors in adipose tissue, is an indication of the progress that is being made in the further understanding of molecular and cellular events that affect adipose tissue growth and, ultimately, adipose tissue microcirculation.

Adipose Tissue↗

PubMed1993

Three simple devices for preventing development of Aedes aegypti larvae in water jars.

We developed three types of covers that are easily fabricated from plastic screen locally manufactured in Thailand. The covers were designed to permit normal use of water jars for drinking, utility water uses, and water storage. Tests of the covers in the laboratory and field demonstrated that they could completely prevent successful development of Aedes aegypti (L.) in water jars. Initial experience in a village setting demonstrated that these devices were readily manufactured and used in a community-based program. Village residents adapted the covers to local patterns of water use, collecting rainwater through the screen and adjusting cover use to water depth.

Aedes↗

PubMedDate not supplied

Microbiological characterization of freatobiont organisms: trial of an analytical protocol and hygienic implications.

The objective of the present study lies in verifing the applicability of an analytical protocol to characterize the microbiology of the surface and gut of freatobiont organisms. The fundamental hypothesis of the study is that the subsurface microinvertebrates represent a protective condition for bacteria, whose presence in potable spring water is rigorously excluded by european standards of quality. The study was conducted between August 1996 and March 1998. Sediment samples were collected from the spring system of "Presciano", whose waters come from the regional aquifer of the Gran Sasso Massif in Italy (L'Aquila, Abruzzo). Drawings of samples were conducted at two different depths (-70 cm and -150 cm). The extration of the fauna (including copepodes) from sediments were achieved with the aid of a Wild M3 microscope. Isolate freatobiont organisms were placed in a sterile Petri plate and subjected to three washings. The liquids of the second and third washings were microbiological analyzed proceeding, in the course of the third washing, to squash the organisms with the aid of a sterile iron handle. Among the microinvertebrates, the copepod Harpacticoida Nitocrella pescei is the most represented species from the two levels of depth. In all, were isolated and identified 106 bacterial species; of these species only 12 (11.3%) did not show any adaptation to the temperature of 35 degrees C. The analytical protocol permitted to make evident a different distribution of microbial species between the two kinds of washing liquids, and this leads to considerate appropriate the adopted protocol. Even if the number of sediment samples analyzed was a few it was identified a great variety of microbial genera and species the greater part of which were mesophilic. This is a consequence of an adaptability that could be favoured by the presence of freatobiont fauna and that concern even microorganisms usually considered "faecal contamination indicators".

Adaptation, Physiological↗

PubMedDate not supplied

Mammalian hibernation: lessons for organ preparation?

The adaptations to low environmental temperatures exhibited in mammalian hibernation are many and varied, and involve molecular and cellular mechanisms as well as the systematic physiology of the whole organism. Natural torpidity is characterised by a profound reduction in body temperature and other functions lasting from a few hours to several weeks. Controlled reduction of heart rate, respiration and oxygen consumption is followed by the fall in body temperature. However, thermoregulation persists such that a decrease in ambient temperature below dangerous levels typically triggers arousal, and shivering and non-shivering thermogenesis from brown fat provide the heat to restore body temperature to normal levels. Many of the cellular mechanisms for survival are similar to those brought into play during medium-term storage of organs destined for transplantation. For example maintenance of ionic regulation and membrane fluxes is fundamental to cell survival and function at low body temperatures. Differences between hibernating and non-hibernating species are marked by differences in Na+/K+ transport and Ca++pumps. These in turn are probably associated with alterations in the lipoproteins of the plasma membrane and inner mitochondrial membrane. We have accordingly conducted a series of pilot studies in captured Richardson's ground squirrels kept in laboratory conditions as a model for hypothermic organ preservation. Tissue function was compared during the summer (non-hibernating season) with that in the winter when the animals could be: (i) in deep hibernation in a cold chamber at 4 degree C; (ii) maintained in an ambient temperature of 4 degree C but active and awake; or (iii) active at an ambient temperature of 22 degree C. The studies involved: whole animal monitoring of standard physiological parameters; whole organ (kidney) storage and transplantation for viability assessment; storage and functional assessment on an ex vivo test circuit with capacity for perfusion at normothermic and hypothermic temperatures; measurement of thyroid function; measurements of total nucleotides (ATP, ADP and AMP)and ratios by standard techniques after freeze-clamping of organs; similar nucleotide and pH measurements using31P-NMR as a non-invasive whole animal technique; and measurement of O2 uptake and gluconeogenesis using isolated renal tubules and isolated hepatocytes. Marked differences in cold tolerance were demonstrated between organs taken from hibernating versus non-hibernating individuals. In particular kidneys transplanted from animals in deep hibernation were capable of withstanding up to 72 hours of cold storage as compared with up to 24 hours in non-hibernating squirrels or in comparable sized rats. Adaptations which might provide valuable clues in our attempts to better preserve human organs for transplantation are explored in some depth in this report.

Journal Article↗