[Efficacy of recombinant human growth hormone treatment in children born small for gestational age with syndromic and non-syndromic short stature]

Objective: To analyse the efficacy of recombinant human growth hormone (rhGH) treatment in children born small for gestational age (SGA) with syndormic and non-syndormic short stature. Methods: The clinical data of 59 children born SGA who were diagnosed as short stature and admitted to the Center of Endocrinology, Genetics and Metabolism, Beijing Children's Hospital from July 2012 to June 2021 were collected and analyzed. According to the 2019 consensus on short stature, they were divided into syndromic group and non-syndromic group. Before treatment and 6, 12, 18 and 24 months after treatment, height standard deviation score (Ht-SDS), difference of height standard deviation (∆Ht-SDS) and homeostasis model assessment-insulin resistance index (HOMA-IR) were compared between groups, while Ht-SDS and HOMA-IR were compared before and after treatment. Independent t test or Kruskal-Wallis test were used for comparison between the 2 groups, and paired t test or Mann-Whitney U test were used for the intra-group comparison. Results: Among the 59 cases, 37 were males and 22 females, aged (5.5±2.3) years. There was no significant difference in Ht-SDS after 12 months of treatment between 2 groups (0.9±0.4 vs. 1.2±0.4, t=1.68, P=0.104) or in height SDS after 24 months of treatment (1.4±0.7 vs. 1.9±0.5, t=1.52, P=0.151). After 12 months of treatment, the insulin resistance index of the non-syndromic group was significantly higher than that of the syndromic group (2.29 (1.43, 2.99) vs. 0.90 (0.55, 1.40), Z=-2.95, P=0.003). There were significant differences in Ht-SDS between 6 months and before treatment, 12 months and 6 months in syndromic type (Z=7.65, 2.83 P<0.001, P=0.020), but all were significant differences in non-syndromic type between 6 months and before treatment, 12 months and 6 months, 18 months and 12 months, 24 months and 18 months (Z=11.95, 7.54, 4.26, 3.83, all P<0.001). Conclusion: The efficacy of rhGH treatment in children born SGA is comparable between syndromic and non-syndromic short stature cases, but non-syndromic children treated with rhGH need more frequent follow-up due to the risk of insulin resistance.

[Effect of reducing-opioids consumption on postoperative delirium incidence in elderly patients after gastric cancer surgery]

Objective: To evaluate the effect of reducing-opioids on postoperative delirium (POD) incidence in elderly patients with gastric cancer surgery. Methods: From July 2016 to September 2021, 130 elderly patients undergoing scheduled gastric cancer surgery in Zhejiang Cancer Hospital were selected and divided into conventional opioid general anesthesia group (group A) and reducing-opioids general anesthesia group (group B) according to random number table. Postoperative analgesic pump formula: group A: 0.2% ropivacaine and 1 μg/ml sufentanil solution; Group B: 0.2% ropivacaine solution. POD assessment was performed once daily between 8 am and 8 pm for 3 days after surgery. The primary outcome measures were POD incidence 3 days after surgery, and the secondary outcome measures included anaesthesia related adverse events 3 days after surgery, such as nausea and vomiting, postoperative fever and fatigue. Results: Among the 130 patients, 7 patients were excluded because they did not comply with the POD test after operation. Finally, 123 elderly patients completed the study. There were 59 cases in group A, aged (73±5) years, including 45 males, and 64 cases in group B, aged (71±6) years, including 56 males. The incidence of total POD 3 days after surgery in group A and B was 30.5% (18/59) and 18.8% (12/64), respectively, with no statistical significance (P>0.05). However, POD incidence at 48 and 72 h after operation in group A [27.1% (16/59) and 16.9% (10/59)] was higher than that in group B [10.9% (8/64) and 4.7% (3/64), both P<0.05]. The incidence of nausea and vomiting in group A was higher than that in group B [15.3% (9/59) vs 1.6% (1/64), P<0.05]. Conclusion: Reducing-opioids consumption have no effect on the incidence of total POD 3 d after gastric cancer surgery in elderly patients, but can reduce the risk of POD 48-72 h after surgery.

[Diagnosis and treatment status of perioperative anemia in patients with gastrointestinal neoplasms: a multi-center study in Hubei Province]

Objective: To investigate the incidence and treatment of perioperative anemia in patients with gastrointestinal neoplasms in Hubei Province. Methods: The clinicopathological data of 7 474 patients with gastrointestinal neoplasms in 62 hospitals in 15 cities (state) of Hubei Province in 2019 were collected in the form of network database. There were 4 749 males and 2 725 females. The median age of the patients was 62 years (range: 17 to 96 years). The hemoglobin value of the first time in hospital and the first day after operation was used as the criterion of preoperative anemia and postoperative anemia. Anemia was defined as male hemoglobin <120 g/L and female hemoglobin <110.0 g/L, mild anemia as 90 to normal, moderate anemia as 60 to <90 g/L, severe anemia as <60 g/L. The t test and χ² test were used for inter-group comparison. Results: The overall incidence of preoperative anemia was 38.60%(2 885/7 474), and the incidences of mild anemia, moderate anemia and severe anemia were 25.09%(1 875/7 474), 11.37%(850/7 474) and 2.14%(160/7 474), respectively. The overall incidence of postoperative anemia was 61.40%(4 589/7 474). The incidence of mild anemia, moderate anemia and severe anemia were 48.73%(3 642/7 474), 12.20%(912/7 474) and 0.47%(35/7 474), respectively. The proportion of preoperative anemia patients receiving treatment was 26.86% (775/2 885), and the proportion of postoperative anemia patients receiving treatment was 14.93% (685/4 589). The proportions of preoperative anemia patients in grade ⅢA, grade ⅢB, and grade ⅡA hospitals receiving treatment were 26.12% (649/2 485), 32.32% (85/263), and 29.93% (41/137), and the proportions of postoperative anemia patients receiving treatment were 14.61% (592/4 052), 22.05% (73/331), and 9.71% (20/206). The proportion of intraoperative blood transfusion (16.74% (483/2 885) vs. 3.05% (140/4 589), χ²=434.555, P<0.01) and the incidence of postoperative complications (17.78% (513/2 885) vs. 14.08% (646/4 589), χ²=18.553, P<0.01) in the preoperative anemia group were higher than those in the non-anemia group, and the postoperative hospital stay in the preoperative anemia group was longer than that in the non-anemia group ((14.1±7.3) days vs. (13.3±6.2) days, t=5.202, P<0.01). Conclusions: The incidence of perioperative anemia in patients with gastrointestinal neoplasms is high. Preoperative anemia can increase the demand for intraoperative blood transfusion and affect the short-term prognosis of patients. At present, the concept of standardized treatment of perioperative anemia among gastrointestinal surgeons in Hubei Province needs to be improved.

A region-matching method for pulse transit time estimation: potential for improving the accuracy in determining carotid femoral pulse wave velocity

Carotid femoral pulse wave velocity (cfPWV) is the 'gold standard' for assessment of arterial stiffness. The reliability of cfPWV measurement depends on the estimation of pulse transit time (PTT). This study aimed to validate a region-matching method for determining PTT and cfPWV against the existing 'foot-to-foot' methods. A cohort of 81 subjects (33 males and 48 females) aged 25-80 (45.1±15.7 years) were studied. PTTs were estimated by the region matching and 'foot-to-foot' methods ('diastole minimum', 'maximum first derivative', 'maximum second derivative' and 'tangent intersection' methods) with manual identification as the reference method and were subsequently used to calculate cfPWV. In a subgroup of 30 individuals, the measurements were repeated after 1 h. There were excellent correlations between cfPWV obtained by the reference method and all the estimated methods (r>0.9, P<0.001 for all), except the diastole minimum method (r=0.793, P<0.001). The region-matching method yielded cfPWV with a better accuracy (mean difference=-0.161 m s(-1), limits of agreement: -0.79 to 0.46 m s(-1)) and repeatability (mean difference=-0.228 m s(-1), intraclass correlation coefficient=0.957) comparing with the 'foot-to-foot' methods. These results demonstrate that the proposed region-matching method is more accurate and suitable for PTT estimation and cfPWV measurement.

A simple empirical model for the clarification-thickening process in wastewater treatment plants

In wastewater treatment plants (WWTPs), activated sludge is thickened in secondary settling tanks and recycled into the biological reactor to maintain enough biomass for wastewater treatment. Accurately estimating the activated sludge concentration in the lower portion of the secondary clarifiers is of great importance for evaluating and controlling the sludge recycled ratio, ensuring smooth and efficient operation of the WWTP. By dividing the overall activated sludge-thickening curve into a hindered zone and a compression zone, an empirical model describing activated sludge thickening in the compression zone was obtained by empirical regression. This empirical model was developed through experiments conducted using sludge from five WWTPs, and validated by the measured data from a sixth WWTP, which fit the model well (R² = 0.98, p < 0.001). The model requires application of only one parameter, the sludge volume index (SVI), which is readily incorporated into routine analysis. By combining this model with the conservation of mass equation, an empirical model for compression settling was also developed. Finally, the effects of denitrification and addition of a polymer were also analysed because of their effect on sludge thickening, which can be useful for WWTP operation, e.g., improving wastewater treatment or the proper use of the polymer.

Current progress of the biological single-ion microbeam at FUDAN

A biological microbeam for precisely positioned single-ion/single cell irradiation is built in the Institute of Modern Physics in Fudan University, Shanghai, China, based on the tandem accelerator (2 × 3MV) in the laboratory. In this paper, the developing progress of the FUDAN microbeam is reported, including the newly constructed beam line, the microbeam collimator, the ion detection system, and the cell-imaging and targeting systems. Statistical models are proposed for evaluating the spatial resolution and dosage precision of the microbeam. By taking the collimated ions as a Gaussian beam, the spatial resolution can be evaluated by the full width at half maximum of the 2-D Gaussian distribution, which is determined by fitting the proportions of peripheral pits outside specific radii in the pit clusters etched on ion track detectors to a 2-D Gaussian distribution. In the preset hitting of defined ion number, by taking the real delivered number of ions as an independent identically distributed random variable (iidrv), according to the Law of Large Numbers and Central Limit Theorem, the expected value μ and standard deviation σ of the real delivered ion number in a preset N-ion hitting can be determined by approaching the normal distribution of N (μ, σ (2)/n) with the proportions of the mean counts of pits in multiple pit clusters on ion track detectors. By the values of μ, σ and additional assumptions, statistical dosage precision evaluations can be made on the preset hitting. From the linear fit curve of μ(N) and the power function fit curve of σ(N) on different preset ion numbers, characteristic factors k, b, A, p can be extracted for a precision evaluation independent of the specific preset ion number.

Cadmium directly induced mitochondrial dysfunction of human embryonic kidney cells

Cadmium (Cd) is the major component of polluted environment, which has numerous undesirable effects on health. Cd could induce apoptosis of HEK293 cells, and the mitochondria may play a key role. However, the mode of action is unclear. In the present study, we aimed to evaluate the ability of the Cd to induce dysfunction of mitochondria. We examined the effect of cadmium chloride (1, 5 and 10 μM) on mitochondrial membrane permeability and potential as well as oxidative stress markers in mitochondria isolated from HEK293 cells. We found that Cd could directly increase in permeability and decrease in membrane potential of mitochondria, even resulted in mitochondrial swelling, and that Cd could inhibit the activities of ATPase, lactate dehydrogenase (LDH), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), enhanced the levels of reactive oxygen species (ROS) and lipid peroxidation (LPO). On the whole, the results show that Cd can directly lead to mitochondrial dysfunction of HEK293 cells, including increased permeability, inhibiting respiration and evoking oxidative stress. Thus, for the first time, this paper makes an overall analysis of Cd-induced changes of structure and function of isolated mitochondria. Our findings may also have general implications in Cd-induced apoptosis by mitochondria pathway.

Distance determined by the angular declination below the horizon

A biological system is often more efficient when it takes advantage of the regularities in its environment. Like other terrestrial creatures, our spatial sense relies on the regularities associated with the ground surface. A simple, but important, ecological fact is that the field of view of the ground surface extends upwards from near (feet) to infinity (horizon). It forms the basis of a trigonometric relationship wherein the further an object on the ground is, the higher in the field of view it looks, with an object at infinity being seen at the horizon. Here, we provide support for the hypothesis that the visual system uses the angular declination below the horizon for distance judgement. Using a visually directed action task, we found that when the angular declination was increased by binocularly viewing through base-up prisms, the observer underestimated distance. After adapting to the same prisms, however, the observer overestimated distance on prism removal. Most significantly, we show that the distance overestimation as an after-effect of prism adaptation was due to a lowered perceived eye level, which reduced the object's angular declination below the horizon.

Effects on endogenous acetaldehyde production by disulfiram and ethanol feeding on rat pancreas

Exogenous acetaldehyde infusion can induce pancreatitis-like injury of the pancreas in some isolated pancreas models, whereas in vivo such treatment has failed to induce pancreatitis. In vivo exogenous acetaldehyde may not be effective because it is rapidly metabolized. The aim of this study was to investigate whether endogenous acetaldehyde accumulates in the pancreas after ethanol feeding when acetaldehyde metabolism is blocked by disulfiram, and whether this treatment can induce pancreatitis-like injury in the rat. The liver was studied for comparison. In part I of the experiment, adult male Wistar rats were given water (n = 24), ethanol (n = 24), disulfiram (n = 24), and ethanol plus disulfiram for 1 week (n = 24) or 3 weeks (n = 24) and for 3 weeks with (n = 6) and without (n = 6) hypovolemia. In part II of the experiment, rats were given water (n = 6), ethanol (n = 6), and high-dose disulfiram (n = 6) and ethanol plus high-dose disulfiram (n = 6). Ethanol and acetaldehyde concentrations in blood, liver, and pancreas were measured. Animal behavior was monitored, and weight changes, plasma amylase activity, water content, and histomorphology of the pancreas and liver were studied without knowing the group. No increases in plasma amylase activity and no histomorphologic changes in the pancreas were observed under light or electron microscopy in part I of the experiment. In part II, treatment with ethanol induced acetaldehyde accumulation in the liver (33.6 +/- 2.6 micromol/L), but to a lesser degree in the blood (9.6 +/- micromol/L) and pancreas (5.0 +/-.2 micromol/L). Ethanol plus disulfiram induced marked accumulation of acetaldehyde in the liver (83.2 +/- 15.9 micromol/L), blood (280.0 +/- 47.4 micromol/L), and pancreas (43.6 +/- 4.7 micromol/L). When tissue acetaldehyde levels reached 30 to 40 micromol/L, we found a decrease in zymogen granules along with formation of small intracytoplasmic vacuolizations in the acinar cells and accumulation of lipid droplets in the hepatocytes, whereas physiologic signs of pancreatitis (hyperamylasemia, edema) or increases in liver enzymes did not develop. High levels of acetaldehyde accumulate in the liver and pancreas with the treatment described. Although this was accompanied by lipid degeneration of the hepatocytes and some subcellular changes in the acinar cells, physiologic signs of pancreatitis did not develop. Thus acetaldehyde accumulation alone, or in combination with hypovolemia, is not responsible for the induction of acute pancreatitis.

Extrapancreatic multiorgan injury in a severe sublethal acute pancreatitis model

In order to develop a new severe but sublethal acute pancreatitis model for the study of clinically relevant extrapancreatic multiorgan injury, we have induced acute pancreatitis in a rat model by intraductal injection with low dose and moderate concentration of bile acid under low pressure. We examined the structural and functional features in the pancreas, lung, liver and kidney. The animals were divided into two groups: the bile acid injection group and the control group. In the bile acid injection group, acute necrotizing pancreatitis was induced by intraductal administration of 0.2 ml of 2.0% bile acid under 30 cm H2O pressure, while the controls underwent the sham operation. The two groups were divided into six subgroups (8 rats for each) and sacrificed at 12, 24, 36, 48, 72 and 144 h, respectively. The pancreatitis induced hyperamylasemia, ascites, pancreatic oedema, haemorrhage, acinar cell necrosis and extensive fat necrosis without early mortality. Accompanied with the pancreatic injury, the function and histologic changes have developed continuously in the kidney and liver for 72 and 144 h in the bile acid injection animals respectively. No pancreatitis associated pulmonary changes were found. Taking into account the results with the two previously developed models of pancreatitis, we conclude that the extrapancreatic injury in acute pancreatitis is found in the liver, kidney and lung, in that order, depending on the severity of pancreatitis. The present sublethal pancreatitis model, in comparison with the two previously studied acute pancreatitis models, is perfect for pathogenetic and therapeutic study of liver and renal changes in acute necrotizing pancreatitis.

Extrapancreatic organ manifestations in a moderately severe acute pancreatitis model

In order to study the extent of clinically relevant extrapancreatic organ injury in a moderately severe pancreatitis model, we examined the structural and functional features of the pancreas, lung, liver and kidney in a rat model simulating gallstone pancreatitis. The animals were divided into three groups: the low-ligation group, the high-ligation group and the control group, and sacrificed at 6, 24, 42, 60 and 96 h. In the low-ligation group, moderately severe acute pancreatitis was induced by the ligation of the common biliopancreatic duct plus intralipid intragastric injection, while controls underwent the ligation of the bile duct above the pancreas (the high-ligation group) or only sham operation (the control group) with fat injection. The pancreatitis induced hyperamylasemia, pancreatic oedema, haemorrhage, acinar cell necrosis and extensive fat necrosis. Accompanied with a peak value of serum amylase activity 24 h after the induction, the kidney changes developed, characterized by decrease in urine output, increase in serum urea and creatinine, and proximal convoluted tubular damage under electron microscope. There were no pancreatitis associated lung or liver changes. These results suggest that this model can be used to study the pathogenesis and therapy of renal injury during acute moderately severe pancreatitis.

Ultrathin cutting needle biopsy histology in the tissue diagnosis of acute pancreatitis--experimental study and application in a human case

BACKGROUND AND AIMS

This study was to assess whether the tissue obtained with an ultrathin cutting needle, that is as thin as used for aspiration cytology and bacteriology, can give enough material to diagnose acute pancreatitis in rat model and in a human case.

METHODS

Wistar rats were randomly allocated into control group (n = 6), cerulein group (n = 6), ligation group (n = 6) and bile salt group (n = 6). In the cerulein, ligation and bile salt groups acute pancreatitis was induced by cerulein intraperitoneal injections, low ligation of common biliopancreatic duct and sodium taurodeoxycholate intraductal injection, respectively. Serum amylase activity was measured and a large cut specimen and two ultrathin needle biopsy specimens were obtained from the pancreas for light microscopic histology. Oedema, acinar cell necrosis, haemorrhage or fat necrosis, and leukocyte infiltration were evaluated semiquantitatively and compared with large cut specimens.

RESULTS

The pancreatitis groups revealed different severity in oedema, acinar cell necrosis, haemorrhage or fat necrosis, and leukocyte infiltration. The needle biopsy showed 100% sensitivity and 100% specificity in the diagnosis of acute pancreatitis. The histopathologic scores showed a good and significant correlation between ultrathin biopsy and large cut specimens in all the four histologic parameters, especially in oedema and acinar cell necrosis. A human case is presented, whose percutaneous ultrathin needle biopsy histology was successfully applied for diagnosing acute pancreatitis.

CONCLUSIONS

The ultrathin needle biopsy histology can give enough material for the diagnosis of acute pancreatitis. Further studies with ultrasonography guided percutanous or endosonography guided transduodenal technique will be needed to assess the role of tissue sampling in acute pancreatitis.

Perceiving binocular depth with reference to a common surface

A common surface is a spatial regularity of our terrestrial environment. For instance, we walk on the common ground surface, lay a variety of objects on the table top, and display our favorite paintings on the wall. It has been proposed that the visual system utilizes this regularity as a reference frame for coding objects' distances. Presumably, by treating the common surface as such--i.e. an anticipated constant--the visual system can reduce its coding redundancy, and divert its resources to representing other information. For intermediate-distance space perception, it has been found that absolute distance judgment is most accurate when a common ground surface is available. Here we explored if the common surface also serves as the reference frame for the processing of binocular-disparity information, which is a predominant cue for near-distance space perception. We capitalized on an established observation where the perceived slant of a surface with linear binocular-disparity gradient is underestimated. Clearly, if the visual system utilizes this incorrectly represented slant surface as a reference frame for coding the objects' locations, the perceived depth separation between the objects will be adversely affected. Our results confirm this, by showing that the depth judgment of objects (two laterally separated vertical lines) on, or in the vicinity of, the surface is underestimated. Furthermore, we show that the impact of the common surface on perceived depth separation most likely occurs at the surface-representation level where the visual surface has been explicitly delineated, rather than at the earlier disparity-processing level.

Sensory eye dominance

BACKGROUND

Sensory eye dominance is revealed in tasks like the Red Lens test and binocular rivalry. To understand its neural basis, we used a new protocol based on binocular rivalry to quantify its consequent interocular imbalance. Then we investigated whether the extent or sign of interocular imbalance is correlated with the difference in monocular contrast responses at threshold and suprathreshold and with the observer's motor eye dominance.

METHODS

To evaluate sensory eye dominance, the stimulus intensity in each eye during rivalry was adjusted to achieve equal predominance. The difference in stimulus intensity constitutes the interocular imbalance. Standard procedures were used to measure monocular spatial contrast sensitivity, suprathreshold brightness judgment, and motor eye dominance.

RESULTS

There was no positive correlation between interocular imbalance (sensory eye dominance) and motor eye dominance. No systematic correlation was found between interocular imbalance and monocular contrast sensitivities at 1 and 3 cycles/degree. Correlation coefficient between interocular imbalance and monocular suprathreshold brightness judgment was close to significant, suggesting that a difference in monocular brightness percept might (in part) account for interocular imbalance. But this explanation is only partial, since the difference in the monocular brightness percept was too small to account for the interocular imbalance.

CONCLUSIONS

Interocular imbalance is a sensory eye dominance that cannot be equated with motor eye dominance. It manifests largely as a binocular phenomenon, which bears little relationship with the monocular neural mechanisms of contrast detection and brightness perception.

Sequential priming of 3-D perceptual organization

In four experiments, the effects of sequential priming on the perceptual organization of complex three-dimensional (3-D) displays were examined. Observers were asked to view stereoscopic arrays and to search an embedded subset of items for an odd-colored target while 3-D orientation of the stimuli was varied randomly between trials. Search times decreased reliably when 3-D stimulus orientation was unchanged on consecutive trials, indicating substantial sequential priming by 3-D stimulus layout. The priming was nonsensory and was independent of priming by additional stimulus characteristics. Finally, priming by 3-D layout was unaffected by observers' foreknowledge of display orientation. Results indicate that perceptual organization of 3-D stimuli is guided by a short-term trace of 3-D spatial relationships between stimuli.

Apoptosis in acute pancreatitis

BACKGROUND

Apoptosis may be involved in the mechanism of acinar cell injury in acute experimental pancreatitis.

AIM

This study was to investigate whether apoptosis also is involved in human acute pancreatitis.

METHOD

A needle biopsy pancreatic specimen was obtained from a patient with acute oedematous pancreatitis. The specimen was stained with In Situ Cell Death Detection Kit. Similar specimen from a patient undergoing pancreatoduodenectomy for bile duct cancer served as a control.

RESULTS

Extended acinar cell apoptosis was found in the pancreatitis specimen. No single apoptotic cell was found in the control pancreas.

CONCLUSION

Apoptosis probably is involved not only in acute experimental pancreatitis but also in human acute oedematous pancreatitis. The induction and role of apoptosis in pancreatis is discussed based on literature.

Asymmetry in 3-D perceptual organization: ground-like surface superior to ceiling-like surface

Attneave (1954) and Barlow (1961) proposed that the visual system might increase efficiency of representation by preferentially encoding spatiotemporally redundant patterns of the external world. The present experiments tested the application of this principle to three-dimensional (3-D) perceptual organization, capitalizing on the ecological constraint that human observers must frequently interact with objects arranged on the ground or on a surface parallel to it (Gibson, 1950). Observers performed a task that required them to perceptually segregate and search multiple items distributed in depth and embedded within a larger, 3-D array of distractors. Stimulus displays were organized to globally recede top-away in depth, as if attached to an underlying ground-like surface, or bottom-away, as if attached to an overhanging ceiling-like surface; ground-like and ceiling-like displays differed only in the direction of disparity gradient within the displays. Primary findings revealed superior performance with ground-like displays, suggesting that spatially and stereoscopically distributed items are more easily organized to represent an ecologically representative pattern, even when no inherent physical regularities favor that pattern.

Binocular rivalry and visual awareness: the role of attention

When the right eye and the left eye view dissimilar scenes, the observer does not experience a stable superimposed percept of the images presented to the two eyes, but instead perceives an alternation between the images seen by each eye. A critical question confronting this robust and intriguing phenomenon of binocular rivalry is how the visual system selects the image to be perceived (dominant). The current main-stream literature emphasizes a bottom-up explanation in which the rivalry stimulus with the higher contour strength has the advantage, and becomes dominant in rivalry. Nevertheless, some workers in the past have favored an attention-selection explanation for binocular rivalry. We investigated the role of attention in binocular rivalry by employing novel psychophysical paradigms which capitalized on several established phenomena (e.g. the Cheshire Cat effect, attention cueing, pop-out effect). Our results revealed two major aspects of attention modulation in binocular rivalry. We found that a dominant image is less likely to be suppressed when voluntary attention is directed to it. This suggests the role of voluntary attention in retaining the dominant image in visual awareness. Second, a rivalry stimulus is more likely to become dominant if accompanied by a pop-out cue (in the same eye and proximity). Since a pop-out cue attracts involuntary attention to its location/eye, this result suggests that cue-mediated involuntary attention can promote the ability of a rivalry stimulus to reach visual awareness.

Perceptual organization of apparent motion in the Ternus display

A typical Ternus display has three sequentially presented frames, in which frame 1 consists of three motion tokens, frame 2 (blank) defines the interstimulus interval, and frame 3 has similar motion tokens with their relative positions shifted to the right. Interestingly, what appears to be a seemingly simple arrangement of stimuli can induce one of two distinct apparent-motion percepts in the observer. The first is an element-motion perception where the left-end token is seen to jump over its two neighboring tokens (inner tokens) to the right end of the display. The second is a group-motion perception where the entire display of the three tokens is seen to move to the right. How does the visual system choose between these two apparent-motion perceptions? It is hypothesized that the choice of motion perception is determined in part by the perceptual organization of the motion tokens. Specifically, a group-motion perception is experienced when a strong grouping tendency exists among the motion tokens belonging to the same frame. Conversely, an element-motion perception is experienced when a strong grouping tendency exists between the inner motion tokens in frames 1 and 3 (i.e. the two tokens that overlap in space between frames). We tested this hypothesis by varying the perceptual organization of the motion tokens. Both spatial (form similarity, 3-D proximity, common surface/common region, and occlusion) and temporal (motion priming) factors of perceptual organization were tested. We found that the apparent-motion perception of the Ternus display can be predictably affected, in a manner consistent with the perceptual organization hypothesis.

Extrapancreatic organ impairment in caerulein induced pancreatitis

BACKGROUND AND AIMS

Multiorgan function failures are the major fatal complications in acute pancreatitis. In this experiment, we studied 1) the manifestation and time course of extrapancreatic organ damage in an acute pancreatitis model and 2) whether the obstructive liver damage in this model is caused by the obstruction of common biliopancreatic duct compressed by oedematous pancreas.

MATERIAL AND METHODS

80 male Wistar rats were divided into two groups: control and caerulein groups (five subgroups in each group). In the caerulein group, the acute pancreatitis was induced by caerulein intraperitoneal injections. In the controls equal volume of saline was injected. Two subgroups, one in caerulein and one in control groups, had an intrapancreatic bile duct stent inserted transduodenally before the injections. The pancreas, liver, lung and kidney tissues and blood samples were obtained for the measurement or analysis of interstitial oedema, plasma amylase, alanine aminotransferase, bilirubin, urea, creatinine, alkaline phosphatase, lactate dehydrogenase, blood gas and electron microscopy at 1, 6, 12 and 24 hours after the last injection in unstented animals, and at 6 hours in stented animals.

RESULTS

Lungs and kidney remained unchanged. Liver damage was found during the first 6-12 hours, manifest as increased plasma alanine aminotransferase and bilirubin and dilatation of bile canaliculi and hepatocyte damage in electron microscopy. The intrapancreatic bile duct stent did not resolve these changes.

CONCLUSIONS

The liver may be the first evolved extrapancreatic organ in the early stage in this mild oedematous pancreatitis model and the hepatocyte damage is not caused by the obstruction of common biliopancreatic duct compressed by the oedematous pancreas.

Illusory-contour formation affected by luminance contrast polarity

We report a new type of illusory contour (Illusory-O) whose formation is contingent upon the contrast polarity of its juxtaposed inducing elements being similar, i.e. both elements must either be positive or negative in contrast sign. To test the hypothesis that this contingency is primarily dictated by factors that determine amodal surface completion (occlusion) between the inducing elements we conducted a series of experiments employing known spatial properties of the amodal completion mechanism, to show that spatial conditions unfavorable to occlusion lead to a concurrent weakening of the Illusory-O formation. For instance, we found that when the juxtaposed inducing elements (solid rectangles) were spatially misaligned, or when their spatial separation increased, our observers rated the perception of the Illusory-O as reduced. We also showed that, in addition to using solid-form inducing elements, the Illusory-O can be induced by line terminals, as long as these lines respect the requirements of the amodal completion mechanism such as similar contrast polarity and spatial alignment. Then we demonstrated that the role of the amodal completion mechanism is not limited to our particular arrangement of inducing elements by showing that the formation of the illusory Necker cube also relies on similar contrast polarity. Finally, to explain why some illusory contours like the Illusory-O are dependent on contrast polarity while others (e.g. Kanizsa square) are not, we propose that the key rests upon the visual system's presumption of occlusion. That is, in forming the illusory contour, if the visual system infers that it is a byproduct of the inducing elements being occluded, then having inducing elements of similar contrast polarity becomes a prerequisite. This assumption can be traced to the occurrence in the real world where partially occluded objects usually have visible parts (on both ends) with similar contrast polarity. Along this line of thinking, we suggest a plausible neural circuitry that may be implemented to form both contrast polarity sensitive and insensitive types of illusory contours.

Terrain influences the accurate judgement of distance

Mathematically, three-dimensional space can be represented differently by the cartesian, polar, and other coordinate systems. However, in physical sciences, the choice of representation system is restricted by the need to simplify a machine's computation while enhancing its efficiency. Does the brain, for the same reasons, 'select' the most cost-efficient way to represent the three-dimensional location of objects? As we frequently interact with objects on the common ground surface, it might be beneficial for the visual system to code an object's location using a ground-surface-based reference frame. More precisely, the brain could use a quasi-two-dimensional coordinate system (x(s), y(s)) with respect to the ground surface (s), rather than a strictly three-dimensional coordinate system (x, y, z), thus reducing coding redundancy and simplifying computations. Here we provide support for this view by studying human psychophysical performance in perceiving absolute distance and in visually directed action tasks. For example, when an object was seen on a continuous, homogeneous texture ground surface, the observer judged the distance to the object accurately. However, when similar surface information was unavailable, for example, when the object was seen across a gap in the ground, or across distinct texture regions, distance judgement was impaired.

Identification of PN1, a predominant voltage-dependent sodium channel expressed principally in peripheral neurons

Membrane excitability in different tissues is due, in large part, to the selective expression of distinct genes encoding the voltage-dependent sodium channel. Although the predominant sodium channels in brain, skeletal muscle, and cardiac muscle have been identified, the major sodium channel types responsible for excitability within the peripheral nervous system have remained elusive. We now describe the deduced primary structure of a sodium channel, peripheral nerve type 1 (PN1), which is expressed at high levels throughout the peripheral nervous system and is targeted to nerve terminals of cultured dorsal root ganglion neurons. Studies using cultured PC12 cells indicate that both expression and targeting of PN1 is induced by treatment of the cells with nerve growth factor. The preferential localization suggests that the PN1 sodium channel plays a specific role in nerve excitability.

Visual attention to surfaces in three-dimensional space

Although attention plays a significant role in vision, its spatial deployment and spread in the third dimension is not well understood. In visual search experiments we show that we cannot easily focus attention across isodepth loci unless they are part of a well-formed surface with locally coplanar elements. Yet we can easily spread our attention selectively across well-formed surfaces that span an extreme range of stereoscopic depths. In cueing experiments, we show that this spread of attention is, in part, obligatory. Attentional selectivity is reduced when targets and distractors are coplanar with or rest on a common receding stereoscopic plane. We conclude that attention cannot be efficiently allocated to arbitrary depths and extents in space but is linked to and spreads automatically across perceived surfaces.