Search PubMed⌕ Search

Biomedical subjects

S Nishida

Publications and source records attributed to S Nishida.

At least 163 records · Page 9Linked to original sources
PubMed1998

Comparison of cyclooxygenase-1 and -2 inhibitory activities of various nonsteroidal anti-inflammatory drugs using human platelets and synovial cells.

Recent studies have shown that cyclooxygenase exists in two isozyme forms. Since differences in the pharmacological profiles of nonsteroidal anti-inflammatory drugs (NSAIDs) might be accounted for by varying degrees of selectivity for these isozymes, cyclooxygenase-1 and -2, the relative potency of various NSAIDs in inhibiting their activities was examined in intact human cells. We used human platelets cyclooxygenase-1 and interleukin-1beta-stimulated human synovial cell cyclooxygenase-2 for measuring cyclooxygenase selectivity. The presence of the enzymes was confirmed by immunoblotting and immunoprecipitation analysis, and by the reverse transcriptase-polymerase chain reaction. Mean IC50 values (microM) for human platelet cyclooxygenase-1 and interleukin-1beta-stimulated human synovial cell cyclooxygenase-2 and cyclooxygenase-1/-2 IC50 ratio of various NSAIDs were as follows: aspirin, 3.2, 26, 0.12; diclofenac, 0.037, 0.00097, 38; etodolac, 122, 0.68, 179; ibuprofen, 3.0, 3.5, 0.86; indomethacin, 0.013, 0.044, 0.30; loxoprofen (active metabolite), 0.38, 0.12, 3.2; NS-398, 12, 0.0095, 1263; oxaprozin, 2.2, 36, 0.061; zaltoprofen, 1.3, 0.34, 3.8; respectively. Our bioassay system employing intact human cells to assess the cyclooxygenase selectivity of NSAIDs may provide clinically useful information.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1998

Effect of monoclonal anti-human gp130 antibody (GPX7) on bone turnover in normal and ovariectomized rats.

We examined the effects of a monoclonal antihuman gp130 antibody (GPX7), which is known to inhibit interleukin-6 (IL-6) and leukemia inhibitory factor-mediated responses in human cells on the bone metabolism in normal and ovariectomized (OVX), 7-month-old, Wistar rats for 8 weeks. After confirming the cross-reactivity of the antibody in suppressing the IL-6-mediated proliferation of rat liver cells, GPX7 was injected once a week at doses of 1 (low dose) or 4 (high dose) mg/kg body weight (BW). In the lumbar body, bone mineral density values and the trabecular bone volume (BV/TV) were maintained in the GPX7 groups. The values of the trabecular osteoclast surface and number in the GPX7 high-dose group were significantly smaller than those in the OVX controls. The double-labeled surface and bone formation rates in the GPX7 high-dose group were significantly increased. In the proximal tibia, however, the bone mineral content and BV/ TV values in the GPX7 groups were smaller, but the trabecular thickness value in the GPX7 high-dose group was larger than in the OVX control. The single-labeled surface in the GPX7 high-dose group was significantly larger than that in the OVX control rats. Though the parameter values of trabecular osteoclasts were apparently smaller, the differences were not significant. 17-beta estradiol (0.125 mg/kg BW a week) administration prevented the bone loss by reducing the parameters of bone formation and resorption in both the lumbar and the proximal tibia. The antibody administration to the normal rats did not cause any significant changes in the parameters of bone mass and turnover. These data demonstrate that while GPX7 modulates the bone turnover after ovariectomy in rats, it does not compensate for the action of estrogen after ovariectomy in rats.

Alkaline Phosphatase↗
PubMed1998

Vascular leiomyosarcoma arising from the inferior vena cava diagnosed by intraluminal biopsy.

A 61-year-old woman developed pain in the right thigh, paraplagia of the lower extremities and lumbago in November 1996. A lumbar spine roentgenogram showed lytic change in L2, and magnetic resonance imaging showed a patchy destructive lesion and compression of the dural sac from the right by a tumour. Computed tomography (CT) myelography showed a motheaten destructive lesion in L2 and projection of the tumour into the spinal canal. Abdominal ultrasound, CT and cavography showed dilatation of the inferior vena cava (IVC) and an intraluminal tumour about 2x2.8x4 cm in size in the IVC. The tumour arose from the IVC just beneath the renal vein and extended to just short of the right atrium. Both vertebral and intraluminal biopsy materials showed the same morphology, in which atypical spindle cells admixed with multinucleated giant cells proliferated in a fascicular growth pattern. Neoplastic cells were strongly positive for alpha-smooth muscle actin. We diagnosed vascular leiomyosarcoma arising from the IVC with metastasis to the lumbar vertebrae. Cases of vascular leiomyosarcoma diagnosed by intraluminal biopsy are rare.

Biopsy↗
PubMed1998

Allograft rejection of small bowel transplantation in pigs.

Small bowel allograft rejection in large animals has yet to be well defined. There are no specific early signs of graft rejection. The present experiments were undertaken to compare acute small bowel allograft rejection in pigs with and without FK506 and also to examine the usefulness of mucosal biopsies. Thirty-six outbred Large-White pigs were divided into (1) group 1 (n = 9): nonimmunosuppressed recipients; (2) group 2 (n = 8): FK506-immunosuppressed recipients; (3) group 3 (n = 2): autotransplant controls; and (4) donors (n = 17). Orthotopic small bowel transplantations were performed with Thiry-Vella loops for daily biopsies. The survival rate of group 2 was significantly longer than that of group 1 (P < 0.05). One best survivor in group 2 was killed at postoperative day (POD) 365. Treatment by FK506 prevented rejection, but most of the pigs died of pneumonia. In group 1, rejection began on POD 3 and progressed to severe rejection rapidly within 7 days. In group 2, rejection began from POD 6 to POD 8, but either remained mild or spontaneously improved. The differences in the routine laboratory data and the tumor necrosis factor-alpha level were not evident between the groups. Histological studies of repeated graft biopsies are thus considered to be essential for detecting signs of graft rejection.

Animals↗
PubMed1998

Diabetes-induced and age-related changes in fatty acid proportions of plasma lipids in rats.

Diabetes-induced and age-related proportional changes in plasma fatty acids of triglycerides (TG), phospholipids (PL), and cholesteryl esters (CE) were investigated using streptozotocin-induced diabetic and control rats. Among n-6 fatty acids from diabetic rat plasma, increased proportions of 18:2n-6 and 20:3n-6 in all three lipid classes and of 18:3n-6 in PL at 1-3 months old and in TG at 3-5 months old were observed. The proportions of 20:4n-6 decreased in both PL and CE, but were unchanged in diabetic TG. Among the n-3 fatty acids, in the early stage, diabetes caused increases in the proportions of 18:3n-3 in PL and CE and of 20:5n-3 and 22:6n-3 in TG, while 22:5n-3 was decreased later in the disease course. These results suggest reduced delta 5-desaturase activities on 20:3n-6 but not on 20:4n-3, while delta 6-desaturase activity on 18:2n-6 was essentially unaffected. Furthermore, the reduction in delta 9-desaturase activity in diabetic rats may well explain the decreases in the proportions of 16:1n-7 and 18:1n-7. However, the proportion of 18:1n-9, another product of delta 9-desaturase, was significantly increased in CE and PL as compared to the controls. Thus, there was a discrepancy between our results and those of earlier studies with respect to the n-9, n-6, and n-3 fatty acid proportions of plasma lipids in diabetic rats. We also investigated age-related changes in the proportions of plasma fatty acids. Although rather small, age-related changes were evident in both diabetic and control rats.

Age Factors↗
PubMed1998

Biliary tract cancer accompanied by anomalous junction of pancreaticobiliary ductal system in adults.

BACKGROUND: Anomalous junction of the pancreaticobiliary ductal system (AJPBDS) is a congenital anomaly in which the junction is located outside the duodenal wall. Recently, attention has been focused on the high incidence of malignancy in this anomaly. The purpose of this study was to clarify the clinicopathological features of this anomaly and to determine the appropriate surgical approach for biliary tract cancer associated with AJPBDS. METHODS: The data for 38 patients with AJPBDS, including 14 who had been treated for biliary tract cancer (2 with bile duct cancer and 12 with gallbladder cancer), were retrospectively reviewed. We assessed the clinical features, characteristics of the tumor, operative procedure, and outcome for each patient. RESULTS: The incidence of malignancy in AJPBDS was 17.8% (2 patients with bile duct cancer and 3 with gallbladder cancer) in the bile duct dilatation group (n = 28) and 90% (9 patients with gallbladder cancer) in the no-dilatation group (n = 10) . The mean length of the common channel was 24.7 mm (range 20 to 35 mm) . Resection with lymphadenectomy was performed in 9 (64.3%) of 14 patients, and curative resection in 5 of these 9 patients. Ten (71%) of the 14 patients had lymph node involvement noted either at the time of initial diagnosis or at surgery. The incidence of lymph node metastasis was closely related to the depth of tumor involvement. Ten patients died of recurrence or primary cancer, from 3 to 30 months after operation. Four patients are still alive without recurrent disease from 2.5 to 13 years after operation. CONCLUSION: For patients with AJPBDS without bile duct dilatation, prophylactic cholecystectomy is recommended even if no malignant lesion is found in the gallbladder because of the high incidence of gallbladder cancer and the poor prognosis. Both early detection and curative resection of the tumor are essential for successful treatment of biliary tract cancer.

Adenocarcinoma↗
PubMed1998

Time course of morphine withdrawal and preproenkephalin gene expression in the periaqueductal gray of rats.

We have previously reported the increase of preproenkephalin (PPE) mRNA in the caudal periaqueductal gray (PAG) of rats during morphine withdrawal. In this study, it was further evidenced that PPE mRNA in the caudal PAG was not increased by various kinds of stressor, suggesting that the increase in PPE mRNA in the caudal PAG is specific to morphine withdrawal. In order to investigate the physiological significance of the increase of PPE mRNA in the caudal PAG, we compared the time course of the increase of PPE mRNA in the caudal PAG with that of naloxone-precipitated or spontaneous morphine withdrawal signs. The increase of plasma corticosterone (PCS: 52 and 52 microg/100 ml; control group, 18 and 15 microg/100 ml) and body weight loss (-6 and -9%; control group, 0 and -1%) were observed but PPE mRNA increase was not detected 1 and 2 h after naloxone in morphine treated rats. PPE mRNA increased by 37 to 56%, while PCS elevation and body weight loss gradually diminished 4 h to 2 days after naloxone. A total of 12 h after spontaneous withdrawal, PCS was prominently increased (51 microg/100 ml; control group, 12 microg/100 ml), but body weight and PPE mRNA were not affected. One day after spontaneous withdrawal, PCS elevation (38 microg/100 ml; control group, 8 microg/100 ml) and body weight loss (-5%; control group, +3%) were observed and PPE mRNA also increased by 42%. Two to 3 days after the final morphine injection, PCS recovered to control level and body weight loss gradually disappeared, while PPE mRNA was still increased by 74 to 46%. These results suggest that PPE gene expression in the caudal PAG is stimulated in the recuperative phase of these morphine withdrawal signs.

Animals↗
PubMed1998

Malignancies of human thyroid tumors and dynamic magnetic resonance imaging (MRI).

Time intensity curves for gadolinium-diethylene triaminepentacetic acid (Gd-DTPA) enhanced magnetic resonance imaging (MRI), namely dynamic MRI, were determined for thyroid diseases and compared with findings of histopathologic examination. Time intensity curves for solid lesions were determined, excluding cases with secondary changes such as calcification, hemorrhage, necrosis and fibrosis. Three different patterns of time intensity curves were observed: rapid washout, delayed washout and no change. In our previous study, malignant grades of thyroid tumors were estimated immunohistochemically by epidermal growth factor receptor (EGFR) antibody. In most of malignant diseases and a few benign diseases that had marked cell proliferative activity with staining EGFR strongly, the time intensity curve displayed a delayed washout pattern, in which intensity was above 1/2-maximal value within 10 min after injection Gd-DTPA. Almost all benign diseases and a few well differentiated carcinomas displayed a rapid washout pastern, in which intensity was decreased to lower than 1/2 of peak grade within 10 min following injection and showed staining EGFR weakly. Benign diseases showing no change of time intensity curve, did not almost show aEGFR positive cell. These findings suggested that the time intensity curve obtained from dynamic MRI might indicate differentiated grades and cell proliferating activity of thyroid tumors.

Contrast Media↗
PubMed1998

Short-term treatment of recombinant murine interleukin-4 rapidly inhibits bone formation in normal and ovariectomized mice.

Estrogen deficiency contributes to an increase in bone resorption and bone formation characterized by a high rate of bone turnover. Interleukin-4 (IL-4) is a rapid and potent inhibitor of bone resorption. We examined the short term in vivo effects of recombinant murine IL-4 (rmIL-4) on bone remodeling in normal and ovariectomized mice. Eight-week-old mice were randomized into the following five groups: (1) sham-operated mice (sham); (2) sham-operated mice infused with rmIL-4; (3) ovariectomized mice (ovx); (4) ovx infused with rmIL-4; and (5) ovx replaced by 10 or 20 microg of 17beta-estradiol (E2) for 14 or 28 days after ovariectomy, respectively. rmIL-4 at a dose of 5 microg/day was infused into ovx and sham for 3 days prior to sacrifice. Analyses were performed 14 and 28 days after operation. An increase in serum alkaline phosphatase and urinary deoxypyridinoline levels induced by ovariectomy was inhibited by the 3-day infusion of rmIL-4. In ovx, serum and urinary IL-6 levels were also increased significantly 14 days after ovariectomy, which were restored by E2 but not by rmIL-4. Histomorphometrical analysis of trabecular bone revealed that the 3-day infusion of rmIL-4 inhibited the high rate of bone turnover induced by ovariectomy, such as an increase in the osteoclastic surface (Oc.S/BS), number of osteoclasts per mm bone surface (N.Oc/BS), mineralized surface per mm bone surface (MS/BS), and bone mineral apposition rate (MAR). A significant decrease in the bone volume (BV/TV) observed in ovx was not modulated by a 3-day infusion of rmIL-4 prior to sacrifice. In sham, rmIL-4 also caused a significant decrease in the Oc.S/BS, N.Oc/BS, MS/BS, and MAR, but the BV/TV was not modulated by rmIL-4. We conclude that short term infusion of rmIL-4 in vivo rapidly inhibits not only bone resorption but also its formation in both sham-operated and ovariectomized growing mice, resulting in a low rate of bone turnover without modulating bone volume.

Alkaline Phosphatase↗
PubMed1998

Effects of a weekly injection of human parathyroid hormone (1-34) and withdrawal on bone mass, strength, and turnover in mature ovariectomized rats.

One hundred fifteen Wistar rats, 7 months of age, were ovariectomized (ovx) or sham-operated to evaluate the effects of a weekly injection of human parathyroid hormone (hPTH) and withdrawal on the bone mass, strength, and turnover in mature ovariectomized rats. At 3 months, ovx rats were given a weekly injection of hPTH(1-34) at the respective doses of 0 (vehicle), 10, and 90 microg/kg body weight (BW) for 3 months. Then, hPTH-treated rats were divided into two groups each: continuously treated groups, and the groups treated with vehicle only for another 3 months. Weekly hPTH injections at doses of 10 or 90 microg/kg BW maintained the lumbar BMD values and increased the values of the femoral cortical bone, increasing the bone formation rates in the trabecular, endocortical, and periosteal envelopes. Trabecular osteoclasts were increased in the 90 microg/kg dose group. Trabecular bone surface relative to the volume was decreased by hPTH. The compressive load of the lumbar bone and the bending moment of the midfemur were increased. The lumbar compressive load values, corrected for BMD and volume, and the moment of inertia of the midfemur were also increased. The intracortical porosity values were not increased by the treatment. After withdrawal of hPTH treatment, the BMD values in both the lumbar and the midfemur were reduced to ovx control levels. The bone mass stimulated by the 90 microg/kg dose was reduced faster than that by the 10 microg/kg dose. However, the parameters of bone strength were still larger than those of the ovx controls after cessation of the hPTH treatment. Thus, a weekly hPTH injection effectively stimulated the bone formation in both the trabecular and cortical bone, leading to positive effects on mass and structure of the bone. These data suggest the possibility of benefits of both a lower frequency of hPTH injections as well as high-frequency injections for human osteoporotics.

Absorptiometry, Photon↗
PubMed1998

Prednisolone prevents decreases in trabecular bone mass and strength by reducing bone resorption and bone formation defect in adjuvant-induced arthritic rats.

We examined the effects of prednisolone (PSL) administration in normal female Sprague Dawley rats and adjuvant-induced arthritic rats at the age of 6 weeks. Rats were intramuscularly injected with PSL twice a week at doses of 0 (control), 10, 30, 90, or 270 mg/kg body weight (b.w.). In the normal rats, serum osteocalcin level at 14 days and serum carboxyterminal pyridinoline cross-linked telopeptide of type 1 collagen (1CTP) level at 28 days in the 270 mg/kg dose group was lower than the respective value in control animals. The BMC and the trabecular bone formation rate (BFR/BS) of the lumbar body (L-4) in the 270 mg/kg dose group at 14 and 28 days were significantly lower than the values in the control rats. In the arthritic rats, however, serum osteocalcin levels in the PSL-treated groups did not differ compared with arthritic controls. The serum 1CTP levels in all of the PSL-treated groups were significantly reduced at 28 days. The age-dependent increases in the L4 BMC, BMD, and L-3 ultimate compressive load values were maintained. The BFR/BS values in the 90 mg/kg and 270 mg/kg dose groups were significantly higher than those in the arthritic control rats. The trabecular osteoclast number and surface values in all of the PSL-treated groups were significantly lower than the values in arthritic controls. These data demonstrate that PSL administration prevented reduction in bone mass and strength of the lumbar trabecular bone in adjuvant-induced arthritic rats by reducing the increase in bone resorption and the decrease in bone formation at both the local and systemic levels.

Animals↗
PubMed1998

Bone marrow cell development and trabecular bone dynamics after ovariectomy in ddy mice.

To clarify the relationship between the sequential changes of trabecular bone turnover and bone marrow cell development in ovariectomized (ovx) mice, bilateral tibiae of 8-week-old ddy mice were obtained. Histomorphometric analyses of the trabecular bone of the proximal tibia of ovx mice revealed increases in the bone formation rate and the osteoclast surface for the first 28 days postovariectomy. The trabecular bone volume showed a rapid decrease for the first 28 days and a steady state for the subsequent 14 days. In bone marrow cell culture experiments, the numbers of total and nonadherent bone marrow cells per tibia obtained from the ovx mice increased. The formation of osteogenic nodules and osteoclast-like multinucleated cells in the marrow cultures obtained from ovx limbs showed a significant increase on days 14 and 28 and returned to the sham-operated level by day 42. The numbers of colony forming units (fibroblastic) and colony forming units (granulocytes and macrophages) that developed from the marrow cells did not differ between the ovx and sham limbs at any time during the study period. Fluorescence-activated cell-sorter analysis revealed no population changes in the cell development of macrophages. These results demonstrate that there are two stages in the development of osteopenia after ovx. During the first 28 days after ovx, the ovariectomy enhances the developmental process from bone marrow stromal cells to osteoblasts and the terminal differentiation from osteoclast precursors to mature osteoclasts. The trabecular bone turnover also increases. In the subsequent 14 days, the changes in the osteogenic and osteoclastogenic potentials of the bone marrow cells are alleviated and the trabecular bone dynamics are in a steady state. The changes in bone marrow cell development are closely associated with those at the trabecular bone surface.

Animals↗
PubMed1998

Pharmacokinetic disposition and arthropathic potential of oral ofloxacin in dogs.

We examined the relation between the pharmacokinetic disposition and arthropathic potential of ofloxacin, a new quinolone antibacterial agent, using both male immature (3-month-old) and mature (18-month-old) beagles. Ofloxacin was orally administered to these dogs at 20 mg/kg once daily for 8 consecutive days, and the animals were killed 2 h after the last treatment. Serum ofloxacin concentrations were repeatedly measured on days 1 and 7 by use of high-performance liquid chromatography (HPLC), and pharmacokinetic parameters were calculated. In addition, on day 8, the drug concentrations in the joint synovial fluid and humeral and femoral condyles were measured. Clinico-pathological tests of blood and serum or histopathological examination of bone specimens were also performed. Arthropathy was macroscopically observed in the cartilage surface of all immature dogs, but not in mature dogs. There were, however, no noticeable differences in pharmacokinetic parameters between the two age groups of dogs or between single and 7-day treatments. In contrast to the occurrence of arthropathic lesions, the synovial fluid and condylar drug concentrations in immature dogs was equal to or lower than those in mature dogs, suggesting that the pharmacokinetic disposition of ofloxacin may not be essential for cartilage lesions.

Administration, Oral↗
PubMed1998

The influences of insulin and food intake on intestinal ornithine transcarbamylase activity in diabetic rats.

Intestinal ornithine transcarbamylase (OTC) activity was studied in rats with experimentally-induced diabetes. After the injection of streptozotocin, OTC activity was approximately 75% that of age-matched controls. Then we investigated the influences of (a) insulin treatment and (b) limiting food-intake, which was adjusted to the control level, on OTC activities in the three segments of the small intestine. (a) Insulin treatment resulted in OTC activities being restored to control levels in all segments of the small intestine, with the disappearance of intestinal epithelial hyperplasia. (b) In limited food-intake rats, OTC activities of the middle and distal segments normalized with insulin treatment. In the proximal segment, however, which showed epithelial hyperplasia, OTC activity was as low as that in untreated STZ rats. These observations suggest that altered regulation of intestinal epithelial over-growth and immoderate food-intake were normalized by insulin treatment, leading to the restoration of normal OTC activity in the small intestine.

Analysis of Variance↗
PubMed1998

Adaptation in the processing of interaural time differences revealed by the auditory localization aftereffect.

Two experiments were conducted involving the auditory localization aftereffect, in which the perceptual lateralization of a test sound having an interaural time difference (ITD) shifts away from that of a prior adapting sound having a different ITD. First, the frequency selectivity of the aftereffect was examined for sinusoids presented through headphones, with various combinations of adapter and test frequencies below 800 Hz, using the method of constant stimuli. The magnitude of the aftereffect was found to be largest when the frequencies of the two tones were similar, and virtually disappeared at a frequency difference of one-half octave. Second, the ITD selectivity of the aftereffect was examined for 400-Hz sinusoids. Subjects' judgments of lateralization were measured directly in terms of the perceived azimuth of the test tone for various combinations of adapter and test ITDs in the range of +/- 625 microseconds. The magnitude of the aftereffect was found to be largest when adapter and test ITDs differed by approximately 250 microseconds. These results were successfully simulated by an interaural cross-correlation model having gain control. The results are consistent with the idea that the gain of ITD-selective units, located after binaural interaction but before across-frequency integration, is changed by recent input.

Humans↗
PubMed1998

Surgical treatment of discrete subaortic stenosis in an adult.

We report on an adult patient with discrete-type subaortic stenosis. A 48-year-old man who had progressed asymptomatically since childhood despite heart murmur was transferred to our hospital. The patient was diagnosed as having severe aortic stenosis with a pressure gradient of 100 mmHg across the aortic valve, associated with a grade II aortic regurgitation. A conventional aortic valve replacement was scheduled. During surgery, the aortic valve was found to be tricuspid but incompetent as a result of shrinking and thickening of the left coronary cusp. A circumferential fibromuscular ridge was observed under the cusps, which corresponded to Kelly's type II discrete subaortic stenosis. Because of the small subaortic area and deformity of the cusp, we performed aortic valve replacement after excision of all cusps and the fibromuscular ridge. Early corrective surgery is recommended for discrete subaortic stenosis to prevention regurgitation progression.

Aortic Valve Stenosis↗
PubMed1998

Use of image-based information in judgments of surface-reflectance properties.

We examined how well we can recover surface-reflectance properties from shading patterns under changes in surface shape. The stimulus we used was a square surface modulated in depth by a low-pass-filtered random field and rendered by the Phong illumination model [Commun. ACM 18, 311 (1975)]. Two different surface images (target and match) were presented side by side, with either the viewing direction or the surface-normal direction rotating around the horizontal axis. The target shape was manipulated by changing the spatial spectrum, and the target reflectance was manipulated by changing the diffuse-reflection coefficient and the specular-reflection exponent (shininess) of the Phong model. The shape parameters of the match stimulus were fixed, but its reflectance parameters were under the control of subjects, who had to make the apparent reflectance of the two surfaces as similar as possible. The results showed that the constant error (difference between simulated and matched values) was large except when the two surfaces had the same shape parameters or when they differed only in scale. The pattern of the constant errors and response variabilities suggests that the judgments of the subjects were based on the similarity of the luminance histogram of the surface image. Our results demonstrate a limitation of surface-reflectance constancy for changes in shape and the importance of image-based information in reflectance judgments. The results are discussed in relation to previous studies that showed effects of spatial layout on surface-reflectance perception.

Color Perception↗