Visual search for moving and stationary items in chimpanzees (Pan troglodytes) and humans (Homo sapiens)

Four visual search experiments were conducted using human and chimpanzee subjects to investigate attentional processing of movement, and perceptual organization based on movement of items. In the first experiment, subjects performed visual searches for a moving target among stationary items, and for a stationary target among moving items. Subjects of both species displayed an advantage in detecting the moving item compared to the stationary one, suggesting the priority of movement in the attentional processing. A second experiment assessed the effect of the coherent movement of items in the search for a stationary target. Facilitative effects of motion coherence were observed only in the performance of human subjects. In the third and fourth experiments, the effect of coherent movement of the reference frame on the search for moving and stationary targets was tested. Related target movements significantly influenced the search performance of both species. The results of the second, third, and fourth experiments suggest that perceptual organization based on coherent movements is partially shared by chimpanzees and humans, and is more highly developed in humans.     

Increased omega complexity and decreased microstate duration in nonmedicated schizophrenic patients

To explore brain functions in schizophrenic patients, the global analytic strategy of multichannel EEG was performed that combines measures of global complexity (Omega), total power (Sigma) and generalized frequency (Phi), and EEG microstate analysis was applied to multichannel EEG data for 24 nonmedicated patients and 24 healthy subjects. The patients had higher Omega and Sigma values, and lower Phi values compared with healthy subjects. Three topographical classes were obtained from all EEG data by EEG microstate analysis. The mean duration of one topographical class in the patients was shortened compared to healthy subjects. These results indicated looser cooperativity, or decreased connectivity of the active brain process and deviant brain information processing in schizophrenic patients.     

Conditional discrimination using 3-dimensional objects by a chimpanzee (Pan troglodytes): tests for derived stimulus relations

A female chimpanzee (Pan troglodytes) was trained on the conditional-discrimination task using 3-dimensional objects under a face-to-face experimental setting. In Experiment 1, the subject was required to pick up the correct comparison object, take it to the sample object, and construct a new paired-object with a specific action. After acquisition of the task, derived stimulus relations (associative symmetry) were tested. The subject showed a significant emergence of symmetry only when the spatial arrangements of stimuli were changed between the baseline and test trials. In Experiment 2, the subject was tested under the condition where the action to constructed paired-object was common to all stimuli. The subject showed significant above-chance performance in the transitivity test, but not in the symmetry tests. The present results are generally consistent with previous studies in chimpanzees that show weak evidence for the emergence of symmetry.     

Evaluation of dipicolinic acid for detection of IMP- or VIM- type metallo-beta-lactamase-producing Pseudomonas aeruginosa clinical isolates

We evaluated dipicolinic acid (DPA) as a chelating agent for detection of IMP- or VIM-type metallo-beta-lactamase (MBL)-producing Pseudomonas aeruginosa clinical isolates. Using the broth microdilution testing in the presence or absence of DPA, MBL producers exhibited 100%, 92%, or 100% of >or=8 times (media, 32 times) reduction of MICs in presence of DPA for ceftazidime, imipenem, or meropenem, respectively. In disk diffusion testing, expansion of growth inhibitory zone of these clinical isolates was clearly observed. Thus, DPA could be useful in the detection for MBL-producing P. aeruginosa clinical isolates.     

Senescence of the temporal impulse response to a luminous pulse

An impulse response function (IRF) to a luminous pulse was derived for 70 normal observers ranging in age from 16 to 86 years. Thresholds were measured for two pulses separated by interstimulus intervals from 6.7 to 180 ms. The pulses had a spatial Gaussian shape (+/-1SD=2.3 degrees diam) and were presented as increments on a 10 cd/m(2) background, having the same chromaticity as the pulse. A spatial 4-alternative forced-choice method was combined with a staircase procedure. Retinal illuminance was equated individually by heterochromatic flicker photometry and control of pupil area. Each IRF was measured four times, in separate sessions, for each observer. IRFs calculated from the threshold data revealed significant age-related changes in the response amplitude of both excitatory and inhibitory phases. In general, there were no significant changes in the time to the first peak or in the first zero crossing. For 12 of 20 observers over 60 years of age, however, the amplitude of the second (inhibitory) phase was reduced relative to the excitatory phase so their IRFs were quite slow and long. Control conditions with three pseudophakic observers and two normal observers with induced blur demonstrated that age-related changes in the IRF under these conditions cannot be ascribed to optical factors. The data suggest that the human visual system generally maintains a stable speed of response to a flash until at least about 80 years of age, even while there are senescent reductions in response signal amplitude.     

Stimulation of butyrate production in the large intestine of weaning piglets by dietary fructooligosaccharides and its influence on the histological variables of the large intestinal mucosa

Fructooligosaccharides (FOS) reach the large intestine and are fermented into short-chain fatty acids (SCFA), lactate, and carbon dioxide. As the major energy source for the epithelial cells of the large intestine, n-butyrate stimulates the proliferation of cells as well as mineral and water absorption from the lumen. We examined the effect of dietary FOS supplementation on luminal SCFA production and its influence on the morphometrical variables of mucosa of the large intestine in commercially available pigs. Six weaning piglets were used. After 7 d of adaptation, three pigs were given a test diet containing FOS (10%) ad libitum for 10 d. The other three remained on the basal diet and were used as controls. At the end of the experiment, their large intestines were removed, and the cecum, gyri centripetales, gyri centrifugales, and rectum were separated. The contents of each portion were collected and measured for SCFA concentration, pH, and moisture. A micrometer was used to measure the crypt depth. The numbers of epithelial and mitotic cells in the crypt columns were also counted. The concentration of SCFA was significantly higher in piglets fed FOS than in the controls. The concentration of n-butyrate was markedly stimulated by FOS. The number of epithelial. mitotic, and mucin-containing cells was higher in piglets fed FOS than in the controls. Accordingly, the crypt depth was larger in the FOS-fed piglets. The luminal n-butyrate concentration showed a significantly positive correlation with the crypt depth and the number of epithelial, mitotic, and mucin-containing cells.     

Effects of nefiracetam on cerebral adenylyl cyclase activity in rats with microsphere embolism-induced memory dysfunction

The effects of nefiracetam on the cerebral adenylyl cyclase (AC) activity of animals with microsphere embolism-induced memory dysfunction were examined. Sustained cerebral ischemia in the right cerebral hemisphere was induced by an injection of microspheres into the right internal carotid artery of rats. To examine learning and memory function, the water maze test was performed from day 7 to day 10 after the operation. The escape latency of the microsphere-embolized (ME) rat in the water maze task was longer than that of the sham-operated (Sham) rat, suggesting that spatial memory dysfunction occurred in the ME rat. Gsalpha and Gi(1/2)alpha protein levels in the cerebral cortex, striatum and hippocampus of the ME rat, when determined on day 11, were similar to those of the Sham rats. The basal AC activity in the striatum, but not in the other two regions, of the ME rat decreased. The AC activity in the presence of 10 microM colforsin daropate (Col), a direct stimulator of AC, was increased by approximately 20-fold in sham animals and 7- to 10-fold in the ME rat. Treatment of the ME rat with 10 mg/kg/d nefiracetam p.o. from day 1 to day 10 after the operation shortened the escape latency, restored the basal AC activity in the striatum, and reversed the Col-induced increases in AC in these three regions without any changes in the cerebral Gsalpha and Gi(1/2)alpha protein levels. These results suggest that nefiracetam-mediated activation of AC activity may contribute to the improvement of memory and learning function in sustained cerebral ischemia.     

Feasibility of duct-to-duct biliary reconstruction in left-lobe adult-living-donor liver transplantation

A Roux-en-Y choledochojejunostomy (CDJ) has been the sole method of choice for the reconstruction of the bile duct in living-donor liver transplantation (LDLT) using left-lobe grafts. In this study, we evaluated the feasibility of duct-to-duct (DD) biliary reconstruction in adult-to-adult LDLT using left-lobe grafts. Between October 1996 and October 2001, 46 adult-to-adult LDLTs using the left lobe were performed at our institution. The DD biliary reconstruction (hepaticocholedochostomy) over a T-tube was performed for seven of the last nine recipients (DD group, n=7), whereas the conventional Roux-en-Y CDJ was used for the remaining cases (CDJ group, n=39). The technical problems and the incidence of biliary complications were compared between the groups. Bile leakage developed in only 1 of 7 (14%) in the DD group (leakage from a T-tube exit site), whereas it occurred in 8 of 39 (20%) in the CDJ group. Up to now, no patients from the DD group developed anastomotic stricture, whereas twelve (30.7%) patients from the CDJ group did. Other complications included bleeding from the Roux-en-Y jejunojejunostomy (n=1) and anastomotic occlusion caused by an internal stent (n=1), and both complications were associated with CDJ. In conclusion, DD anastomosis is a simple and viable option for biliary reconstruction in left-lobe LDLTs. A long-term follow-up, especially regarding the incidence of biliary stricture, is thus warranted in such patients.     

Living-related liver transplantation with renoportal anastomosis for a patient with large spontaneous splenorenal collateral

BACKGROUND: A large splenorenal collateral must be interrupted during liver transplantation to secure adequate portal perfusion. However, this process increases the complexity of the operative procedure and may cause hazardous bleeding. Recently, renoportal anastomosis in portal reconstruction was reported in cadaveric liver transplantation for patients with surgically created splenorenal shunts. We used this technique in a living-related liver transplantation. METHODS: A 29-year-old female with a large spontaneous splenorenal collateral and a portal venous thrombus underwent a living-related liver transplantation. At surgery, the left renal vein was divided and the distal stump was anastomosed to the portal vein of the graft without interrupting collaterals. RESULTS: Adequate portal venous blood flow was maintained throughout the postoperative course. The patient was discharged 9 weeks after transplantation and remains well. CONCLUSION: The renoportal anastomosis could be used for portal reconstruction in living-related liver transplantation for patients with a large splenorenal collateral. It provides adequate portal perfusion without interrupting collateral circulation.