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PubMed1977

Mycosis fungoides. Electron beam therapy.

The most effective treatment of late mycosis fungoides is total skin electron beam therapy. The beam at the Hammersmith Hospital in London has been adapted to treat these patients. Patients with advanced disease who have failed more conservative methods of treatment are irradiated. The electron beam is modified by the use of carbon and copper scatterers to produce an 80 percent depth dose at 5.5, 8 and 11.5 millimeters below the skin surface. The dose achieved in most patients is between 1500 rads and 2600 rads given in 10 to 13 treatments over 5-7 weeks. Recently the higher dose range has been employed and lithium flouride studies have shown that giving these doses from each of 4 fields, the dose achieved on the skin is approximately twice the given dose. The management of patients and the effects of treatment are discussed.

Electrons↗

PubMed1988

The cue interaction model of depth perception: a stability analysis.

In this paper, we offer a stability analysis of "the cue interaction model" of depth perception (House (1984]. Depth estimation using stereopsis suffers from the "matching problem", the problem of correctly matching the retinal image of a feature in one eye, to its retinal image in the other eye. The Cue Interaction Model overcomes this by using monocular cues to disambiguate between the "correct matches" and the "incorrect matches". Its decision making is based on the concept of cooperation and competition in a neural network. A general class of cooperative and competitive models has been mathematically analysed by Amari and Arbib (1977), with special attention given to equilibrium states and stability. In this paper we adapt their methods to study the above model. In particular, we prove that if the parameters are correctly tuned, the model successfully achieves its goals by suppressing the cues which represent the "incorrect matches".

Animals↗

PubMedDate not supplied

The effect of a valine-rich diet on intestinal adaptation to massive small bowel resection in the rat.

BACKGROUND/PURPOSE: Recently, valine, which is one of the branched chain amino acids, has been reported to enhance liver regeneration after hepatectomy in the rat. The aim of this study was to investigate the effect of enteral valine supplementation on intestinal adaptation. MATERIALS/METHODS: Seven-week-old male Lewis rats underwent a 90% small bowel resection. The rats were randomly divided into two groups: group V (valine-rich diet) and group S (standard rat chow), according to the diet. The rats were sacrificed at the operation day and on postoperative days (POD) 7, 14, 30, and 60. The metrics were body weight (BW), blood amino acids, urine organic acids, and morphology of the residual small intestine. RESULTS: The BW and the intestinal wet weight, jejunal crypt depth, and proliferating cell nuclear antigen-positive cells in group V at POD 7 were significantly higher than those values in group S, while those in group V at POD 30 and 60 were smaller than those in group S. The urine methylmalonic acid (MMA) level in group V at POD 30 and 60 was much higher than in group S. CONCLUSION: Valine enhanced intestinal adaptation after massive small bowel resection in the acute phase. However, the long-term supplementation disturbed intestinal adaptation, which might be due to the high production of MMA.

Animals↗

PubMed1996

Moderating effects of physical abuse and perceived social support on the potential to abuse.

This study investigated the moderating effects of perceived prepubertal social support on the relationship between prepubertal childhood physical abuse and child abuse potential as well as on the relationship between a childhood history of abuse and conflict and depth in adult relationships. Three hundred and sixty-nine undergraduate men and women were classified as abused or nonabused based on their responses to the Childhood History Questionnaire. Multiple regression analyses revealed interactions of social support and a childhood history of physical abuse on both the potential to abuse and the quality of participants' relationships with their parents. Differences between abused and nonabused individuals were obtained only under conditions of low perceived social support. When social support was perceived to be high, abused and nonabused individuals did not differ in the potential to abuse or in the ratings of the depth of their relationships with parents. Implications of these findings for the intergenerational transmission of abuse are discussed.

Adaptation, Psychological↗

PubMed1999

Color and luminance in the perception of 1- and 2-dimensional motion.

An isoluminant color grating usually appears to move more slowly than a luminance grating that has the same physical speed. Yet a grating defined by both color and luminance is seen as perceptually unified and moving at a single intermediate speed. In experiments measuring perceived speed and direction, it was found that color- and luminance-based motion signals are combined differently in the perception of 1-D motion than they are in the perception of 2-D motion. Adding color to a moving 1-D luminance pattern, a grating, slows its perceived speed. Adding color to a moving 2-D luminance pattern, a plaid made of orthogonal gratings, leaves its perceived speed unchanged. Analogous results occur for the perception of the direction of 2-D motion. The visual system appears to discount color when analyzing the motion of luminance-bearing 2-D patterns. This strategy has adaptive advantages, making the sensing of object motion more veridical without sacrificing the ability to see motion at isoluminance.

Color Perception↗

PubMed2005

Effect of light intensity on linear shrinkage of photo-activated composite resins during setting.

The purpose of this investigation was to examine the effects of light intensity on linear shrinkage of photo-activated composite resins during setting. The materials used were four commercially available photo-activated composite resins. Three light-irradiation instruments were selected and prepared so as to obtain four light intensities (200, 480, 800 and 1600 mW cm(-2)). The linear shrinkage during setting was examined 10 min after light irradiation using a trial balance plastometer, and the specimen thickness was 2.0 mm for all materials. The depth of cure was examined according to the test method described in the International Organization for Standardization (ISO/FDIS 4049: 2000(E)). In measuring the linear shrinkage 60 s from the start of light irradiation for 10 s, there was a significant correlation (r = 0.89-0.94) between the amount of linear shrinkage and the light intensity: an increase in light intensity produced a greater linear shrinkage. Furthermore, there was a significant correlation (r = 0.92-1.0) between the linear shrinkage and the irradiation time: an increase in irradiation time resulted in a greater linear shrinkage. Values of the depth of cure ranged from 1.69 to 3.75 mm.

Composite Resins↗

PubMed2004

[A study of the difference in intestinal adaptation between the residual jejunum and the ileum in rats with short bowel syndrome].

OBJECTIVES: Controversy remains regarding which residual segment, namely the jejunum or ileum, is more beneficial for intestinal adaptation in patients with short bowel syndrome (SBS). The aim of our study is to evaluate the residual intestinal adaptation after a massive small intestinal resection and thereby determine which of the two residual segments demonstrates a better intestinal adaptation. METHODS: The SBS rats underwent about a 70% resection of either the jejunum or ileum, respectively. Sham rats underwent an ileal transection with a subsequent reanastomosis of the same portion. The body weight was measured every day after the operation. Two weeks after the operation, all rats were sacrificed. The intestinal length, the hematological and serum chemical data, and the histological findings of the residual intestine were investigated in all rats to evaluate the intestinal adaptation. RESULTS: The body weight gain in the rats with the residual ileum (ileum group) was similar to that of the Sham group and better than that of the rats with residual jejunum (jejunum group). The length of the residual intestines in the jejunum group was longer than that in both the sham and ileum groups. Regarding hematological and serum chemical studies, the jejunum group tended to demonstrate more anemia and malnutrition than both the sham and ileum groups. In a histological study, the villous height in both the jejunum and ileum groups was significantly larger than in the preoperative condition. In both groups, the degree of crypt depth only significantly increased in the ileum group in comparison to the preoperative condition. Regarding the thickness of the muscular layers, a no difference was observed among all groups. CONCLUSION: Based on our data, in patients with SBS, the use of the residual ileum was therefore found to be preferable to that of the residual jejunum regarding intestinal adaptation.

Adaptation, Physiological↗

PubMed1992

Anisotropy in an ambiguous kinetic depth effect.

A set of animated stimuli (Lissajous figures), each element of which is physically consistent with two different three-dimensional shapes undergoing rigid rotations about orthogonal axes, is described. Human observers typically show a preference for one shape or the other; this preference may be biased by manipulating various parameters of the stimulus. Fairly good predictions of which shape will be seen are made by using an adaptation of Hildreth's smoothest-velocity-field computation. When a given stimulus is rotated 90 degrees in the picture plane, the resolution of the ambiguity is often different, demonstrating anisotropy in the processing of the figures. The nature of this bias is such that for certain figures subjects see a three-dimensional object rotating about a vertical axis regardless of which two-dimensional orientation is used to present the stimulus. This bias is not predicted by the Hildreth model. One interpretation of the results is that the ambiguity in two-dimensional visual motion (i.e., the aperture problem) is not resolved before the interpretation of the three-dimensional structure.

Anisotropy↗

PubMed1988

Microbial ecology of the terrestrial subsurface.

We have presented a current view of the microbial ecology of the terrestrial subsurface by considering primarily the ecology of shallow aquifer sediments. The properties of the aquifer sediments and groundwater determine their ability to support microbial life and control the abundance and activities of microorganisms. Pore size, nutrient limitations, availability of electron acceptors, and large surface area for attachment all may have major effects on microbial abundance and activities in aquifer material. Microorganisms are the predominant forms of life in the subsurface. They will be found wherever enough space, nutrients, and water are available for them to live. Environmental factors such as pH, temperature, hydrostatic pressure, and dissolved salts also may influence subsurface microbial populations, but these factors do not exhibit great extremes in shallow water table aquifers, and thus only in very deep formations might they limit diversity or preclude the existence of microorganisms. Although the presence and activity of microorganisms in most subsurface environments are predictable, only recently have subsurface microbial populations in shallow subsurface zones been characterized. Aseptic sampling methods have been employed and microbiological and biochemical methods have been adapted to determine the types, abundance, and metabolic activities of microorganisms in subsurface material. Bacteria dominate, but eukaryotic microorganisms also are present. Vertical profile studies of a shallow aquifer in Oklahoma showed that active microbial biomass declined with depth to the unsaturated zone, but was variable in saturated sediments. Such a distribution of active biomass may be common in shallow aquifers. Studies on the lateral distribution of microorganisms in shallow and deep aquifers suggest that microorganisms are transported or migrate over fairly long distances in aquifer sediments. Surficial aquifers may be colonized by vertical or lateral transport and migration of surface microorganisms from recharge areas, but microorganisms could also have colonized when sediments were originally deposited. The biological and physical mechanisms controlling the migration of microorganisms in aquifers are not well understood. The function of shallow aquifers was considered with regard to nutritional ecology. Most pristine aquifers are oligotrophic. Heterotrophic life in these unique ecosystems is supported by secondary organic compounds that filter down from the soil above. The quantity and quality of organic nutrients depend on the age of water and rate of recharge of the aquifer.(ABSTRACT TRUNCATED AT 400 WORDS)

Bacteria↗

PubMed1998

Hippocampal formation theta activity and movement selection.

Hippocampal theta activity results from activation in the ascending synchronizing system. It occurs during sensory/signal processing prior to and coincident with voluntary movements in mammals. The experiments summarized here suggest that it is involved in the organization of motor behaviour. (1) Procaine (a local anaesthetic) infused into the medial septum (MS) abolishes hippocampal theta activity and running behaviour elicited by electrical posterior hypothalamic (PH) stimulation. This indicates that movement elicited by PH stimulation, is dependent on ascending hypothalamo-septal circuitry. (2) Theta can also be recorded in immobile rats prior to the initiation of lateral dodging movements they make in response to conspecific rats attempting to steal their food. Following infusion of atropine into the MS, theta recorded during immobility is abolished and the rats are severely impaired at initiating movements in defence of their food. It is suggested that atropine-sensitive theta is involved in the initiation of movements made by rats in response to sensory stimuli. (3) Rats with fimbria-fornix transections were also less likely to engage in lateral dodging movements in defence of their food, were hyperactive, less thigmotaxic, and defecated more often, compared to control animals. Depth profile analysis of hippocampal field activity in lesioned animals revealed an absence of theta during electrical or chemical pons stimulation. These findings provide evidence that these neural systems are involved in signal processing relevant to movements underlying adaptive behaviour.

Animals↗

PubMed2004

Convergent evolution in mechanical design of lamnid sharks and tunas.

The evolution of 'thunniform' body shapes in several different groups of vertebrates, including whales, ichthyosaurs and several species of large pelagic fishes supports the view that physical and hydromechanical demands provided important selection pressures to optimize body design for locomotion during vertebrate evolution. Recognition of morphological similarities between lamnid sharks (the most well known being the great white and the mako) and tunas has led to a general expectation that they also have converged in their functional design; however, no quantitative data exist on the mechanical performance of the locomotor system in lamnid sharks. Here we examine the swimming kinematics, in vivo muscle dynamics and functional morphology of the force-transmission system in a lamnid shark, and show that the evolutionary convergence in body shape and mechanical design between the distantly related lamnids and tunas is much more than skin deep; it extends to the depths of the myotendinous architecture and the mechanical basis for propulsive movements. We demonstrate that not only have lamnids and tunas converged to a much greater extent than previously known, but they have also developed morphological and functional adaptations in their locomotor systems that are unlike virtually all other fishes.

Animals↗

PubMed1974

Identification of cone mechanisms in graded responses of foveal striate cortex.

1. The earliest electrical response detectable in foveal striate cortex of anaesthetized Rhesus monkeys following light stimulation is a graded potential which is positive at the cortical surface and negative in the grey matter and has a peak latency of about 60 msec. The response is similar at both the on- and the off-phase of a light stimulus.2. The relationship of this graded potential to the depth of the recording electrode, to the latency of extracellular impulses and to post-synaptic potentials suggests that it is generated by the depolarization of cortical cells.3. Action spectra obtained in the presence of strong selective chromatic adaptation indicate the participation of all three cone mechanisms in this response.4. Each cone mechanism contributes a similar potential to the response but antagonism between cone mechanisms is apparent. The proportion in which a cone mechanism contributes to the response varies from one area to another implying topographical differences in the representation of cone mechanisms in striate cortex.

Adaptation, Ocular↗

PubMed1982

The brain-stem projections of pulmonary stretch afferent neurones in cats and rabbits.

1. Micro-electrode recordings were made from slowly adapting pulmonary stretch afferents within the nodose ganglia of cats and rabbits. Recordings sites were distributed throughout the ganglia. 2. The projections of these afferents to the medulla oblongata were studied by antidromic stimulation. 'Point' and 'Field' type depth--threshold curves were interpreted as corresponding to stimulation of the main afferent axons and its branches, respectively. Increases in antidromic latency in conjunction with 'field' contours was additional evidence in support of this interpretation. 3. In cats, most (six out of seven) afferents had extensive branches, and probably also terminations, within the medial subnucleus of the ipsilateral nucleus tractus solitarius (n.t.s.). Two of these, plus one other afferent, also had projections to the lateral and ventrolateral subnuclei. 4. In rabbits the projections of such afferents were similar, i.e. mainly to the medial subnucleus of the n.t.s. (eight out of eleven) but also extending into the nucleus alaris, and occasionally to lateral and ventrolateral subnuclei (two out of eleven) or to both regions (one out of eleven). 5. Branching of single afferents was seen to occur over up to 3 mm of the rostro-caudal extent of the intermediate region of the n.t.s. The significance of the observations is discussed.

Action Potentials↗

PubMed1977

A comparison of the continuous and interrupted suturing techniques.

This investigation compared the efficacy of interrupted and continuous suturing for primary closure of the apically positioned flap. Twenty-two flap procedures were performed on contralateral sites in 10 patients. The 11 sites where interrupted suturing was used had a degree of presurgical periodontal involvement which was similar to that in the 11 contralateral sites where continuous suturing was used. At postsurgical assessment visits, after 3 months and 6 months, gingival health status was evaluated for both groups. Recession, residual pocket depth and loss of attachment were also measured. Analysis of the data for each of these parameters indicated no statistically significant difference between the two groups. However, the overall clinical impression was that interrupted suturing provided better flap adaptation.

Adult↗

PubMed1986

Cognitive and emotional changes during a simulated 686-m deep dive.

Three experienced divers were subjected simultaneously to world record hyperbaric pressures using an oxygen-helium-10% nitrogen breathing mixture. The simulated depth reached by these divers was 686 m (2250 ft). Cognitive and emotional state measures were obtained predive, during compression, decompression, and postdive. Although the divers showed no overt signs of nitrogen narcosis or HPNS, declines in memory, adaptive, and spatial functions were seen at 670 m. These performance deficits were reversed when the divers returned to surface pressures. The observed declines in performance are discussed in light of their implications for future dives.

Adult↗

PubMed1994

True three dimensional stereographic display of 3D reconstructed CT scans of the pelvis and acetabulum.

Fractures of the acetabulum can cause the pelvis to shatter into a wide array of complex configurations which can be difficult to fully delineate preoperatively. In addition to plain radiography and standard computed tomography, technology now allows the reconstruction of magnetic resonance imaging (MRI) and computed tomography (CT) data into virtual objects; three dimensional (3D) representations of anatomy which exist only within the computer memory. Printouts and photographs of 3D reconstructions provide another level of anatomic information to the orthopaedic surgeon. However, current standard displays such as computer and video screens and photographic and radiographic film are all two dimensional (2D) modalities. Displaying 3D reconstructions in this standard 2D fashion, inescapably robs the images of up to one third of the information contained within them--all the true depth information which is the essence of 3D. Shading techniques and perspective have both been utilized to simulate depth, but true depth is still lacking. Recently, the authors have begun using a technique of computerized 3D reconstruction and recording which provides a true 3D display of the reconstructed images. The resultant gain in image realism is profound, somewhat similar to hearing full stereo audiophonic recording compared to monophonic, or to seeing in color rather than black and white. The image generation and display process is a computerized mathematical adaptation of the photographic technique of stereophotography. Once in place, the technique is relatively simple to use and can be achieved in several ways with a minimum of additional hardware. Potential benefits lie in the method's ability to convey, in one 3D display, the true 3D, spatial anatomic configuration of the imaged pelvis. The methods described are common to those forming the fundamental basis for virtual reality imaging. Current users of some 3D reconstruction systems can now easily generate images which can be viewed with all of the depth information restored, into a true 3D display.

Acetabulum↗

PubMed2004

Further evidence that epidermal growth factor enhances the intestinal adaptation following small bowel transplantation.

Recent reports indicate that epidermal growth factor (EGF) plays a crucial role for graft adaptation in rat model of small bowel transplantation (SBT). The administration of EGF enhances intestinal cell proliferating rate and the recovery of mucosal structure. However, the effect of EGF on biological functions including glucose absorption in intestinal graft remains to be elucidated. SBT was performed in the two-step procedure. On the first step, intestinal graft (30-cm jejunum) from Brown Norway rats was exteriorized through abdominal wall as a Thiry-Vella loop in recipient Lewis rats for one week. On the second surgery (POD 7), recipient jejunum was replaced orthotopically by the graft, and transplanted rats were treated intraperitoneally with EGF or its vehicle for 3 days. Analyses of histology and biological functions in the graft were done at POD 14. EGF increased both levels of villus height and crypt depth in the graft of transplanted groups. EGF enhanced the glucose absorption as well as the induction of sodium glucose cotransporter 2- to 3-fold in transplanted groups. Further, EGF stimulated the activities of disaccharidase (maltase and sucrase) and the induction of dipeptide cotransporter. These results demonstrate that EGF enhances the structural and functional adaptation of intestinal grafts after SBT. EGF may be useful therapy for patients following intestinal transplantation.

Adaptation, Physiological↗

PubMed2006

A qualitative study of anterior resection syndrome: the experiences of cancer survivors who have undergone resection surgery.

This study aimed to explore how individuals recovered and adapted following surgical resection of their rectal cancer and the syndrome that occurs as a consequence of this operation. This syndrome, 'anterior resection syndrome', consists of frequency, urgency, fragmentation and incontinence of faeces, and is thought to occur in 90% of patients who have received this type of surgery. Little qualitative research has been undertaken in this area, and this study adds to current quality of life data and explores supportive care strategies that nurses could use to assist patients. This study uses a grounded theory approach and in-depth interviews to explore patient's experiences. Participants were recruited from a cancer unit within the UK. Participants were recruited from a total population sample of 27 patients who had received surgery from 2001 to 2002. Following eligibility criteria to exclude those who had disease progression, seven patients were identified 1 year following surgery. Interviews were used to explore the experience of the syndrome. Three categories were identified: adapting to the physical changes, psychological adaptation and stigma. A secondary theme, running throughout all these categories, was the feeling of confidence and normality. Although the physical changes were expected as a consequence of surgery, most participants described the difficulty in controlling and managing symptoms in their period of recovery. Developing a philosophical stance was important in managing the lack of control and returning to perceived normality, despite the social stigma of bowel problems. Information on a range of strategies to manage physical symptoms is helpful in providing supportive care. Understanding that patients often rely on inappropriate strategies for management and are reluctant to discuss symptoms is important. The specialist nurse has a role in providing supportive care in managing chronic symptoms following cancer treatment.

Adaptation, Physiological↗