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At least 109 records · Page 6Linked to original sources
PubMed1996

[Bowel endometriosis. Eight cases of colorectal resection].

Colo-rectal endometriosis requiring colon resection are reported in 8 patients to illustrated the diagnostic and therapeutic problems encountered in the management of this uncommon localisation. Pericatamenial or catamenial bowel symptoms associated with pelvic genital involvement were encountered in all cases. Clinical examination, barium enema and colonoscopy are essential to guide surgical management looking for multiple localisations. However their diagnostic value is low as endometriosis rarely involves the mucosa. Endosonography appears to be very promising in evaluating the depth of infiltration of the bowel. The treatment of bowel endometriosis is controversial and varies greatly according to the patient's complaints and clinical data. The indications and limits of all treatment modalities including abstention, medical, and surgical treatment are discussed. From the cases reported we conclude that symptomatic bowel endometriosis should be fully excised whenever possible, and the surgical procedure should be adapted to the depth of infiltration. A full thickness excision or bowel resection is mandatory in patients with deep muscularis involvement. These procedures, which are often difficult due to extensive fibrosis and adhesions, may be achieved by laparoscopy in selected patients.

Adult↗
PubMed1989

Pressure adaptation of Na+/K+-ATPase in gills of marine teleosts.

The effects of pressure and temperature on an integral membrane protein, Na+/K+-adenosine triphosphatase (Na+/K+-ATPase), were studied in fish gill membrane preparations from shallow- and deep-living marine teleosts. The inhibition by pressure of maximal velocity of the enzyme is nonlinear, increasing at higher pressures. Na+/K+-ATPases from deep-sea fish were less inhibited by pressure than those of shallow-living species. Habitat temperature also affected the pressure response of the enzyme. As a function of physiological pressure and temperature, the order of increasing pressure-sensitivity was cold, deep-sea less than warm, deep-sea (hydrothermal vents) less than polar = shallow and mid-depth, cold less than shallow, warm. Activation volumes in all species were conserved at 30-60 ml mol-1 at physiological pressures, which may reflect a similar membrane physical state at the actual pressure the animal experiences. Arrhenius plots [In(Na+/K+-ATPase activity) vs 1/T] were steeper for warm-water and shallow-living species than for deep-sea species. The depth at which adaptation was first observed was about 2000 m (approximately equal to 200 atm: 1 atm = 101.3 kPa). The data are consistent with a model of increased membrane fluidity resulting in reduced pressure-sensitivity of Na+/K+-ATPase from deep-sea species.

Acclimatization↗
PubMed2002

Spectral tuning and evolution of short wave-sensitive cone pigments in cottoid fish from Lake Baikal.

The cottoid fishes of Lake Baikal in eastern Siberia provide a unique opportunity to study the evolution of visual pigments in a group of closely related species exposed to different photic environments. Members of this species flock are adapted to different depth habitats down to >1000 m, and both the rod and cone visual pigments display short wave shifts as depth increases. The blue-sensitive cone pigments of the SWS2 class cluster into two species groups with lambda(max) values of 450 and 430 nm, with the pigment in Cottus gobio, a cottoid fish native to Britain, forming a third group with a lambda(max) of 467 nm. The sequences of the SWS2 opsin gene from C. gobio and from two representatives of the 450 and 430 nm Baikal groups are presented. Approximately 6 nm of the spectral difference between C. gobio and the 450 nm Baikal group can be ascribed to the presence of a porphyropsin/rhodopin mixture in C. gobio. Subsequent analysis of amino acid substitutions by site-directed mutagenesis demonstrates that the remainder of the shift from 461 to 450 nm arises from a Thr269Ala substitution and the shift from 450 to 430 nm at least partly from Thr118Ala and Thr118Gly substitutions. The underlying adaptive significance of these substitutions in terms of spectral tuning and signal-to-noise ratio is discussed.

Adaptation, Physiological↗
PubMed1986

Scotopic threshold response of proximal retina in cat.

We describe a new response in proximal retina of cat that is present under scotopic conditions, clearly differs from PII (b-wave and DC component) and contributes a negative potential at threshold to the diffuse electroretinogram (ERG). We have termed this response the scotopic threshold response (STR). Extracellular potentials evoked in response to circular spots of light at dark-adapted threshold, and with dim backgrounds, were recorded with microelectrodes placed intraretinally at different depths. The dark-adapted response of proximal retina (STR) consisted of a graded negative potential to the onset of illumination that maintained amplitude during illumination and decayed back toward the base line at stimulus offset without evidence of a negative-going off response. It thereby differed in form from the photopic M-wave response of proximal retina, which has a negative-going off response. It also did not exhibit spatial tuning, simply increasing in size with stimulus area. In addition, the STR appears to be a rod-driven response whose threshold approximates that of the most sensitive ganglion cells in cat, whereas the M-wave is a much higher threshold cone-driven response. The STR could be clearly distinguished from PII on the basis of its form, depth-distribution, and dynamic range. For example, the STR had its maximum amplitude in the proximal retina at 17% retinal depth, whereas scotopic PII had its maximum in the distal retina at 48% retinal depth. Also, the STR had a lower threshold than PII intraretinally and saturated well below the level of saturation of scotopic PII (rod saturation). By analogy to the PNR and M-wave, the STR is hypothesized to represent either an extracellular voltage arising from proximal retinal neurons or Müller cell responses to K+ released by these neurons. Recording in the vitreous, near the retinal surface, showed that the STR always had a negative polarity. The polarity reversal of the STR at 50-60% retinal depth (from negative, proximal to positive, distal) suggested the presence of a sink proximal to the reversal point and a source distal to it. We also recorded the vitreal ERG in response to diffuse illumination of the dark-adapted retina. The STR could be clearly identified in the scotopic ERG as a threshold negative potential that had been observed previously in the mammalian ERG. The STR differs, therefore, from PII (b-wave and DC component) that is a higher threshold positive component in the diffuse ERG.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

The interplay between stereopsis and structure from motion.

In a series of psychophysical experiments, an adaptation paradigm was employed to study the influence of stereopsis on perception of rotation in an ambiguous kinetic depth (KD) display. Without prior adaptation or stereopsis, a rotating globe undergoes spontaneous reversals in perceived direction of rotation, with successive durations of perceived rotation being random variables. Following 90 sec of viewing a stereoscopic globe undergoing unambiguous rotation, the KD globe appeared to rotate in a direction opposite that experienced during the stereoscopic adaptation period. This adaptation aftereffect was short-lived, and it occurred only when the adaptation and test figures stimulated the same retinal areas, and only when the adaptation and test figures rotated about the same axis. The aftereffect was just as strong when the test and adaptation figures had different shapes, as long as the adaptation figure contained multiple directions of motion imaged at different retinal disparities. Nonstereoscopic adaptation figures had no effect on the perceived direction of rotation of the ambiguous KD figure. These results imply that stereopsis and motion strongly interact in the specification of structure from motion, a result that complements earlier work on this problem.

Adaptation, Ocular↗
PubMed2000

Attentional modulation of motion-in-depth processing.

I used a novel effect of adaptation to a moving stimulus to investigate the role of attention in the processing of motion-in-depth (MID). Following adaptation to expansion, the time required to detect an expanding target in the same location as the adaptation target was significantly longer than following viewing of a constant-sized target. Conversely, following adaptation to contraction, detection times (DTs) for an expanding target were significantly shorter than for a constant-sized adaptation target. Changes in DTs following adaptation to contraction were substantially larger than those following adaptation to expansion. Attentional modulation of MID processing was examined by adding an alphanumeric discrimination task that distracted the observer's attention away from the location of the adaptation target. I compared the magnitude of DT effects while (a) observers passively fixated the alphanumeric sequence (single task condition) and (b) observers performed the discrimination task (dual task condition). DT effects were significantly smaller in the dual task condition than in the single task condition indicating that MID processing is modulated by attention.

Adaptation, Physiological↗
PubMed1975

Critical flicker frequency and the Pulfrich phenomenon.

The critical flicker frequency and the Pulfrich stereophenomenon were both used to investigate the long term effects on temporal resolution and visual latency of wearing a tinted lens in front of one eye for a period of five days. The results obtained from three subjects showed that in every case the critical flicker frequency was depressed by the tinted lens and displayed no adaptive recovery, but the Pulfrich effect displayed a reduction of apparent depth in the median plane indicating the presence of an adaptive recovery. It is postulated that the CFF indicates that the physiological transmission of the visual signal is unaltered over the the five days and the Pulfrich adaptation occurs due to an alteration of the interpretation of the unchanged visual response. That is, the adaptation is a perceptual rather than a physiological one.

Adaptation, Ocular↗
PubMed2000

Bax is required for increased enterocyte apoptosis after massive small bowel resection.

BACKGROUND: Massive small bowel resection (SBR) increases rates of both enterocyte proliferation and apoptosis. Previous studies have demonstrated increased intestinal expression of proapoptotic bax mRNA and protein, as well as the appearance of an 18-kd bax cleavage product within 12 hours of SBR. This study tested the hypothesis that bax is required for postresection increases in enterocyte apoptosis. METHODS: Male bax-null and C57Bl/6 (control) mice underwent either a 50% proximal SBR or sham operation. After 3 days, the remnant ileum was harvested and weighed. Apoptotic indexes, proliferation indexes, villus heights, and crypt depths were determined. RESULTS: The usual adaptive increases in ileal wet weight, crypt depth, and rate of proliferation occurred in both the control and bax-null mice. Resection significantly increased the rate of apoptosis in the control mice; however, it failed to alter the apoptotic index in the bax-null mice. CONCLUSIONS: Bax is necessary for the increase in apoptosis that occurs after SBR, but its absence has no significant effect on short-term adaptation. These findings suggest that enterocyte proliferation and apoptosis are differentially regulated during intestinal adaptation.

Animals↗
PubMedDate not supplied

[Reaction of the body to the effect of barbiturates and the activity of monoaminergic processes in the brain].

The adaptive reaction to barbiturates was studied in the presence of a seasonally varying monoamine content and metabolism in the brain. The effectiveness of amobarbital and monoamine content in mouse brain were determined monthly during 5 years. It has been demonstrated that both adaptive reactivity of mice and monoamine content in the brain show a similar seasonal periodicity. The conclusion is made that adaptive reactivity determining the depth and duration of amobarbital anesthesia correlates mainly with the activity of serotoninergic processes. Activation of adaptive reactions caused by repeated administration of the barbiturate correlates with the activity of dopaminergic processes.

Adaptation, Physiological↗
PubMed1988

Limits of binocular fusion in the short wave sensitive ("blue") cones.

Stereoscopic depth perception is possible when the short wave sensitive (SWS or "Blue") cones are isolated using a yellow adapting field. We have measured the maximum disparity that can be fused (the diplopia threshold) as a function of the separation between pairs of dots or lines. Under all conditions, these diplopia thresholds are the same for the isolated SWS cones as for the entire visual system. In addition, SWS diplopia thresholds vary as a linear function of dot or line separation, so that they exhibit disparity scaling. Further experiments show that disparity scaling is dependent upon the presence of low spatial frequencies in the stimulus and not upon the retinal eccentricity of stimulation. These data indicate that the SWS cones provide information to the disparity processing system through more than one low spatial frequency channel but not through high frequency ones.

Adaptation, Ocular↗
PubMed2006

Combined pharmacotherapy that increases proliferation and decreases apoptosis optimally enhances intestinal adaptation.

BACKGROUND: Adaptation after massive small bowel resection (SBR) is associated with increased rates of enterocyte proliferation (P) and apoptosis (A). In the present study, we sought to determine the effect of dual therapy designed to increase P and simultaneously reduce A. METHODS: C57Bl/6 mice underwent a 50% small bowel resection (SBR) or sham operation, and then received an inhibitor of apoptosis (pan-caspase inhibitor), a stimulus for proliferation (epidermal growth factor; EGF), a combination, or vehicle control. After 3 days, adaptive morphology (villus height, crypt depth) and rates of enterocyte turnover (proliferation and apoptosis) were measured in the remnant ileum. RESULTS: Adaptation in controls and treated with the inhibitor was similar. EGF-treated mice demonstrated an even greater adaptive response. Combined therapy with the inhibitor and EGF resulted in maximal adaptation as gauged by the greatest increases in villus height and crypt depth and ratio of rates of P to A. CONCLUSION: The capacity for adaptation following massive SBR is maintained via tight regulation of cell production and death. Pharmacologic intervention directed at increasing enterocyte proliferation while simultaneously decreasing apoptosis augments adaptation greater than either intervention alone and may provide a useful strategy to clinically amplify adaptation.

Adaptation, Physiological↗
PubMed1977

Human tecg changes during prolonged hyperbaric exposures breathing N2-O2 mixtures.

In an effort to determine whether hyperbaric exposures while breathing N2-O2 mixtures have an effect on cardiac depolarization and repolarization, electrocardiograms of 10 divers participating in four N2-O2 saturation dives were analyzed. In all cases, a decline in heart rate was observed upon compression to saturation depth (20-30%); a slow adaptation and return of heart rate toward normal was observed in those dives where the depth and environmental parameters remained constant. twhenever excursion dives were performed, the heart rate responded by decreasing on deeper excursions and increasing on upward excursions. Hyperbaric bradycardia disappeared after 8 days at pressure during the saturation dives at 50 and 60 feet seawater gauge (fswg), but was still present at this time at 200 fswg. The magnitude of the hyperbaric bradycardia produced by excursion dives following saturation at depth was influenced by the state of adaptation of heart rate. Decompression was uniformly accompanied by a rapid increase in heart rate resulting in a significant elevation in the postdive period. Alterations in myocardial repolarization as evidenced by Q-T interval, ST, and T wave changes were observed. Development of slight right ventricular conduction delay compatible with right ventricular strain was noted in four of the divers during the two deepest dives to 100 and 198 fswg. During the latter dive, progressive decrease in P wave amplitudes and eventual loss of P waves resulting in an apparent nodal rhythm was observed in one diver. Multiple premature ventricular contractions occurred in another diver. These observations, along with the reports by other authors, suggest that the different variables associated with the hyperbaric environment--gas density, pressure, inert gas--have a definite effect on the pacemaker activity of the heart and myocardial depolarization and repolarization.

Adaptation, Physiological↗
PubMed1978

Pressure-adaptive differences in lactate dehydrogenases of congeneric fishes living at different depths.

The muscle-type (M4) lactate dehydrogenases of Sebastolobus altivelis, a deep-water scorpaenid, and S. alascanus, a shallower species, are electrophoretically indistinguishable, yet differ in pressure sensitivities. The lactate dehydrogenase of S. altivelis exhibits lower pressure sensitivities of substrate and coenzyme binding and catalytic rate. Such apparently pressure-adaptive kinetic properties may be important for establishing species depth zonation patterns in the ocean.

Adaptation, Biological↗
PubMed2003

High-speed adaptive interferometer for optical coherence-domain reflectometry through turbid media.

Two-wave mixing in a dynamic holographic film acts as the adaptive beam combiner in a short-coherence interferometer that performs optical coherence-domain reflectometry (OCDR) through turbid media. This approach combines the high spatial resolution and sensitivity of coherence-domain reflectometry with photorefractive quantum-well-based adaptive homodyne detection. A depth resolution of 28 microm and penetration through 16 mean free paths in a turbid medium have been obtained in this adaptive OCDR application.

Interferometry↗