Multiple streams of time consciousness: a new model of retrospective timing

This note suggests a new hypothesis for retrospective timing, that, when one experiences a period of time in which plural contexts progress simultaneously, a stream of time consciousness is formed for each context and a temporal judgment to the period is made for each of the streams. In the experiment, 17 subjects observed an event in which plural contexts progressed simultaneously and estimated the time a certain thing occurred during the event. Subjects' estimated times varied with the number of changes in the context which the subjects were required to judge. The hypothesis was supported.

[Assessment of the various image display systems affected to the visual analysis using 99mTc-GSA liver scintigraphy]

The aim of this study was to evaluate the physical performance for the gray-scale monitor and the image display system of the color monitor with the films using the visual analysis of the liver scintigraphy by 99mTc-DTPA-galactosyl-human serum albumin (GSA). The seven kinds of calibration curves (CC) were applied to convert into both the counts of the density of the films and the intensity of the monitors. The relationship between the intensity and density was evaluated in the 123 patients suspected with hepatic dysfunction. The liver scintigraphy images of 1-minute duration from five to six minutes after administration of 99mTc-GSA were converted according to the seven kinds of CC (861 images per image display system). These images were visually classified by the 16 observers following the five-point scoring system arranged beforehand. The intensity of monitors and the density of films showed positive correlation. Thus the CC for both the intensity and the density was centralized. The CC obtained by the present study was suitable for both monitors and films, respectively. The CC, which had the slope of approximately 4.8 for the monitor and 4.2 for the film, showed a good correlation between the indices of liver functions obtained from the biochemical liver function tests and from the 99mTc-GSA liver scintigraphy. Data suggest that the suitable CC in the three sets of image display system may contribute to the other scintigraphy as well as 99mTc-GSA liver scintigraphy, evaluating the scintigraphy using the visual analysis.

Enhanced responses of the chorda tympani nerve to nonsugar sweeteners in the diabetic db/db mouse

Genetically diabetic db/db mice show greater neural and behavioral responses to sugars than lean control mice. The present study examined chorda tympani responses of db/db mice to nonsugar sweeteners and their inhibition by a sweet response inhibitor, gurmarin. The results showed that responses to sucrose, saccharin, glycine, L-alanine, and D-tryptophan, but not to D-phenylalanine, were approximately 1.5 times greater in db/db mice than in control mice. Treatment of the tongue with gurmarin suppressed responses to these sweeteners in db/db and control mice, but the extent of suppression was considerably smaller in db/db mice. The magnitudes of gurmarin-sensitive components of the response to sweeteners in db/db mice were not significantly different from those in control mice, whereas the magnitudes of gurmarin-insensitive components in db/db mice were about twice as large as those in control mice. These results suggest that the enhancement of chorda tympani responses in db/db mice to sucrose and other nonsugar sweeteners may occur through gurmarin-insensitive membrane components.

Redundancy gain in discrimination of colored lights: effects of complexity and eccentricity

The present study investigated the redundancy gain in discrimination of colored lights. Subjects were requested to discriminate a target from 34 nontarget lights differing from the target in luminance, hue, or both, and RTs were recorded. Experimental variables were the complexity of stimulus pattern and the eccentricity of the target in visual angle. The 35 lights were arranged regularly on an imaginary grid in the low-complexity condition and were arranged randomly in the high-complexity condition. The eccentricity of target was varied from 0 degree to 16 degrees. Only when the stimulus pattern was highly complex and eccentricity was large, the combination of luminance and hue made the subject's discrimination faster than when luminance or hue individually operated as a cue for discrimination. That is, a redundant target effect was found only for a highly complex stimulus pattern and in peripheral vision.

N-linked glycosylation of Drosophila rhodopsin occurs exclusively in the amino-terminal domain and functions in rhodopsin maturation

Immature Drosophila rhodopsin is N-glycosylated, but undergoes complete deglycosylation during the process of protein maturation. In order to elucidate the site of glycosylation and its role in rhodopsin synthesis, we investigated the in vitro and in vivo synthesis of rhodopsin whose putative N-glycosylation sites (Asn-20 and Asn-196) were replaced by isoleucine. The results demonstrated that immature rhodopsin binds a single oligosaccharide chain exclusively at Asn-20 in the N-terminal extracellular domain. Furthermore, the results gave the first evidence directly indicating that deletion of the oligosaccharide chain markedly impedes rhodopsin maturation.

Effects of dobutamine on brain surface microvessels in rats

The effects of dobutamine on the diameters of rat pial vessels were investigated in vivo using a closed cranial window technique. Dobutamine (10(-7)-10(-3) M) was dissolved in artificial cerebrospinal fluid (CSF). Arterioles (17-78 microns in diameter) and venules (20-97 microns in diameter) were observed through the cranial window over the left parietal cortex. Superfusion of the brain surface with only artificial CSF had no effect on vessel diameter. Dobutamine, even at a high concentration of 10(-4) M, did not induce significant diameter changes in the pial vessels, compared with control animals. The arterioles showed marked dilatation (+73%) during superfusion with 10(-3) M dobutamine (p < 0.01 vs. control). The venules were also dilated (+12%), although the increased diameter was not statistically different from controls. Therefore, dobutamine did not induce a dose-dependent dilation. The results strongly suggest that dobutamine at clinical dosages does not have a direct vasomotor effect on brain microvessels.

Enhanced invasion of Tyzzer's organism into cultured mouse hepatocytes by cytochalasin D

The effects of cytoskeleton inhibitors on the invasion of Tyzzer's organism, an obligate intracellular bacterium, into cultured mouse hepatocytes were examined by double immunofluorescence observation and plaque assay. The two techniques gave comparable results. Invasion of bacteria was significantly enhanced by cytochalasin D, a microfilament disrupting drug, and markedly suppressed by vinblastine, a microtubule inhibitor. Another microtubule inhibitor, colchicine, did not show any substantial effect. However, the cytoskeletal system of cultured mouse hepatocytes was sensitive to these three drugs, as judged by inhibition of FITC-dextran uptake. These results suggest that Tyzzer's organisms invade host cells by a unique mechanism that is suppressed by the normal functions of host cell microfilaments.

Effect of protein kinase C inhibitors on cardioprotection by ischemic preconditioning depends on the number of preconditioning episodes

OBJECTIVES

This study examined the possibility that the role of PKC in [corrected] PC, and thus the response to PFC inhibitors, may differ depending on how many ischemic episodes are employed to precondition the heart.

METHODS

In the first series of experiments, myocardial infarct was induced by 30 min of coronary occlusion and 3 h of reperfusion in the rabbit. Infarct size was determined by tetrazolium staining and expressed as a percentage of area at risk (%IS/AR). Prior to the 30-min ischemia, rabbits were subjected to no PC, single PC (i.e., PC with an episode of 5 min ischemia/5 min reperfusion), and repetitive PC (2 cycles of 5 min ischemia/5 min reperfusion) with or without one of three treatments: polymyxin B (PolyB), staurosporine (Stauro), and 8-sulfophenylthephylline (SPT). In the second series of experiments, the rabbits received 5 min of coronary occlusion after repetitive PC with or without PolyB or Stauro treatment. Then, myocardial tissue in the ischemic region was sampled for assay of PKC activity. Untreated rabbits served as controls.

RESULTS

Single and repetitive PC limited %IS/AR to the same extent (%IS/AR = 9.8 +/- 1.9 and 10.4 +/- 2.3, both p < 0.05, vs. the control value of 44.5 +/- 3.4), and single PC was blocked by PolyB (%IS/AR = 43.9 +/- 2.7) and Stauro (%IS/AR = 31.5 +/- 3.2). Although the protocol of PolyB injection maintained the plasma PolyB level during sustained ischemia well above its Ki for PKC, this agent and also Stauro failed to abolish the protection by repetitive PC (%IS/AR = 21.6 +/- 3.0 and 11.4 +/- 4.3, respectively). SPT, an adenosine receptor antagonist, not only blocked single PC (%IS/AR = 44.4 +/- 4.4) but also attenuated protection by repetitive PC (%IS/AR = 28.3 +/- 3.6). Infarct sizes in non-preconditioned hearts were not modified by PolyB, Stauro, or SPT. The ratio of membrane fraction PKC activity to cytosolic fraction PKC activity was elevated by repetitive PC plus 5 min ischemia, and this change in PKC was inhibited in hearts given PolyB and Stauro.

CONCLUSIONS

In contrast to single PC, repetitive PC protects the heart against infarction even when PolyB and Stauro are administered to inhibit PKC during ischemic insult. This difference may be attributable to a PKC-independent mechanism, in which the adenosine receptor may be partly involved.

Regeneration of ultraviolet pigments of vertebrates

We report here the regeneration of the visual pigments of mouse, rat, goldfish and pigeon, which have wavelengths of maximal absorption at 359 nm, 358 nm, 359 nm, and 393 nm, respectively. The construction and functional assays of the ultraviolet or near-ultraviolet pigments from a wide range of vertebrate species will allow us to study the molecular bases of ultraviolet vision for the first time.

Articular cartilage repair. Rabbit experiments with a collagen gel-biomatrix and chondrocytes cultured in it

To repair a full-thickness articular cartilage defect in rabbit knees, we developed a technique of using a collagen gel hardened by cultured allogeneic chondrocytes in it. The gel-chondrocyte composite accumulated an intense metachromatic matrix, and had elasticity and stiffness enough to be shaped easily after 2 weeks' culture in vitro. It was implanted into full-thickness articular cartilage defects. Histologic evaluation was performed up to 6 months after surgery, using a histologic grading scale composed of 5 categories. In the gel-chondrocyte composite implanted group, good repair was observed from as early as 1 day up to 6 months. On the other hand, in the empty control group, no repair was observed 1 day to 2 weeks after the defects were made. At 4 weeks, some repair occurred, but even at 6 months the repair was not good.

Functional characterization of visual and nonvisual pigments of American chameleon (Anolis carolinensis)

Using only 11-cis 3, 4-dehydroretinal as a chromophore in the pure-cone retina, American chameleon (Anolis carolinensis) detects a wide range of color from ultraviolet (UV) to infrared. We previously characterized its visual opsin genes sws1Ac, sws2Ac, rh1Ac, rh2Ac, and LwsAc that encode SWS1Ac, SWS2Ac, RH1Ac, RH2Ac, and LWSAc opsins, respectively, and the pineal gland-specific opsin (PAc) gene. Here we present the light absorption profiles of the visual pigments obtained by expressing these opsins and reconstituting them with 11-cis retinal using the COS1 cell cDNA expression system. The purified SWS1Ac, SWS2Ac, RH1Ac, RH2Ac, LWSAc, and PAc pigments have the wavelengths of maximal absorption at 358, 437, 491, 495, 560, and 482 nm, respectively. SWS1Ac is the first vertebrate UV opsin whose spectral sensitivity has been directly evaluated. RH1 pigments, orthologous to the rod pigments of other vertebrates, are sensitive to hydroxylamine in the dark, exhibiting a cone pigment-like characteristic, probably reflecting their adaptation to the pure cone retina. Interestingly, the blue-sensitive SWS2Ac pigment shows an exceptionally low level of sensitivity to hydroxylamine, possessing a rod pigment-like characteristic.

Lack of selectin-dependent adhesion in prostate cancer cells expressing sialyl Le(x)

BACKGROUND

Recently, it has been reported that upregulation of the oligosaccharide sialyl Le(x) (SLe[x]) in prostate cancer is associated with hormone-resistant, aggressive disease. However, it is not clear that SLe(x) expressed on prostate cancer cells has a biological function related to metastatic potential.

METHODS

The expression levels of SLe(x), sialyl Le(a) (SLe[a]), disialosyl galactosylgloboside (DSGG), monosialosyl galactosylgloboside (MSGG) and variousfucosyltransferases in 3 prostate cancer cell lines were determined. The function of SLe(x) expressed on prostate cancer cell lines was determined by a selectin-dependent adhesion assay.

RESULTS

No prostate cancer cell lines expressed SLe(a), DSGG, or MSGG, but all prostate cancer cells moderately expressed SLe(x). Fucosyltransferase expression did not correlate with the expression of SLe(x), and all prostate cancer cells failed to bind immobilized selectin.

CONCLUSION

The expression of SLe(x) on these prostate cancer cells does not correlate with selectin-dependent adhesion.

Pregnancy among long-term survivors of acute leukemia. A second nationwide survey

A second nationwide survey was conducted to determine the outcome of pregnancy in long-term survivors of acute leukemia and to clarify the influence of treatment on the offspring of long-term survivors. In July 1996, 336 survey responses were received from the 498 Japanese institutions surveyed. A total of 89 cases (39 spouses of male patients and 50 female patients) who had babies during their first remission were analyzed, including 43 patients from the first survey in 1991. Median age at the birth of first baby was 30.7 years for male patients and 28.6 years for female patients. A total of 109 of the 117 pregnancies resulted in live births and eight resulted in abortions. A total of 58 cases had single children and 23 cases had two or more, generally from separate pregnancies, but including two pairs of twins. The infant was male in 59 cases, female in 37 and gender was not reported in 13 cases. Ages of children ranged from 2 months to 20 years at the time of this study and all children were in good health. There were two minor anomalies, both of which were surgically corrected. Of the 81 parents bearing live infants, 75 remained in complete remission. Five fathers died (four of relapse and one of another disease). In conclusion, there was no apparent increase in pregnancy complications or congenital anomalies in the children of long-term survivors with acute leukemia.

Arterial occlusive lesions following wrapping and coating of unruptured aneurysms

Seven patients (mean age 57 years) developed arterial occlusive lesions following both wrapping and coating during surgery for unruptured aneurysms. Five patients had no risk factors for arteriosclerosis, and two had hypertension or diabetes mellitus. The aneurysms were located in the middle cerebral artery in four cases, and the internal carotid artery in three. Both 100%-cellulose cotton (Bemsheet) and cyanoacrylate glue (Biobond) were used as reinforcement materials. Postoperative angiography revealed complete clipping, and no parent artery stenoses, although one patient had a non-symptomatic diffuse narrowing in the entire carotid fork 7 days following surgery. Three patients had progressive stroke 4-5 weeks following surgery, and two had no symptoms. Both reinforcement materials were used as little as necessary in the last two patients, but they had either transient ischemic attacks or progressive stroke 2 months following surgery. Arterial steno-occlusion was confirmed angiographically in all patients. These vascular lesions were probably induced by both direct toxicity of the cyanoacrylate glue and fibrosis or granuloma formation caused by the cotton fibers. The observed angiographical reversibility suggests that the cyanoacrylate glue is more likely to be the cause of the lesions than the cotton fibers.

[Hematological characteristics of hypoplastic MDS patients with chromosomal abnormalities, who had been followed for aplastic anemia with normal karyotypes]

During 1990 to 1993, five patients who had been treated in our hospital for aplastic anemia (AA) with a normal karyotype, were found to have hypoplastic myelodysplastic syndromes (hMDS); three patients with RA, one RAEB, and one RAEB-T, and all of them have chromosomal abnormalities. The mean age of the hMDS patients (4 men, 1 woman) was 51.0 years (range 31-61). We retrospectively studied the hematological features of the 5 cases in the early stage without chromosomal abnormalities. They showed, 1) appearance of erythroblasts (3/5), 2) more reticulocyte counts than typical AA (mean 7.8 x 10(4)/microliter), 3) macrocytic anemia (mean MCV 106fl) in peripheral blood, 4) relative erythroid hyperplasia (M/E ratio 0.2-1.5), and 5) low lymphocyte counts (mean percentage of lymphocytes 32, 8%) in bone marrow. Considering about the differences or transformation between AA and hMDS, it is interesting that all five patients have initially had a normal karyotype and subsequently developed chromosomal abnormalities.

Impaired spermatogenesis in the Japanese eel, Anguilla japonica: possibility of the existence of factors that regulate entry of germ cells into meiosis

In the cultivated male Japanese eel, spermatogonia are the only germ cells present in the testis. Weekly injections of human chorionic gonadotropin (HCG) can induce complete spermatogenesis from proliferation of spermatogonia to spermiogenesis. In some cases, however, HCG injection fails to induce complete spermatogenesis. Testicular morphological observations revealed that HCG-injected eels could be classified into three types based on their testicular conditions. Type 1 eels had a well-developed testis and the milt could be acquired by hand-stripping. In type 2 eels, spermatogenesis was also induced by HCG injection, but testicular size was remarkably smaller than that of type 1 eels, and the milt could not be hand-stripped. At the end of the experiment, type 2 fish had only spermatogonia and a small amount of spermatozoa, but no spermatocytes or spermatids, in their testis. Type 3 eels had thready testis, which did not develop any germ cells during the experimental period. These results suggest that, despite elevations of plasma 11-ketotestosterone levels, HCG injections were not successful in inducing the completion of spermatogenesis in type 2 and type 3 eels. In most spermatogonia of type 2 eels, meiosis was not induced by HCG injections. Furthermore, only few mitotic divisions had occurred as evidenced by the presence of 2(3) to 2(6) late type B spermatogonia in most cysts. This suggests that spermatogonial stem cells undergo four or five, and occasionally six, mitotic divisions before the interruption of spermatogenesis in type 2 eels. It is proposed that those numbers of mitotic divisions are related to a mediator that regulates entry of spermatogonia of the Japanese eel into meiosis.

In situ inhibition of vesicle transport and protein processing in the dominant negative Rab1 mutant of Drosophila

Rab proteins play an essential role in vesicle transport. In particular, RAB1 is thought to participate in the transport of most membrane and secretory proteins. To investigate the role of RAB1 in developing or functioning cells in situ, we constructed transgenic, dominant-negative Rab1 mutants of Drosophila, and examined the protein transport and cellular and subcellular structures of mutant photoreceptor cells. In the transgenic fly, the expression of mutant RAB1 was induced by Gal4 protein, whose expression was triggered by heat treatment (37 degrees C) of the fly. Within several hours after the heat induction, the lumens of the rough endoplasmic reticulum (rER) became swollen, and Golgi bodies were disassembled into vesicle clusters. Corresponding to these changes in cell structure, rhodopsin transport was blocked between the rER and the Golgi body, as indicated by the accumulation of immature rhodopsin carrying a large high-mannose-type oligosaccharide chain. Long-term expression of mutant RAB1 caused the degradation of photoreceptive microvilli and the accumulation of numerous swollen rERs, whereas no distinct changes were found in the axonal regions. These results indicate that, in Drosophila photoreceptor cells, RAB1 contributes to the maintenance of local cell structure by mediating vesicle transport between the rER and Golgi body.

Molecular mechanism of S-modulin action: binding target and effect of ATP

S-Modulin is suggested to increase the light sensitivity of rods by inhibiting phosphorylation of light-activated rhodopsin (Rh*) at high Ca2+ concentrations. The inhibition of rhodopsin phosphorylation was almost constant over a wide range of the Rh*/S-modulin ratio (10(-4)-approximately 10[1]). A 125I-labeled cross-linker that had been conjugated with S-modulin interacted with a protein of 60 kDa, a molecular mass close to that of frog rhodopsin kinase. These results suggested that the target molecule of S-modulin is rhodopsin kinase. To investigate the mechanism of the S-modulin action, we measured rhodopsin phosphorylation in the presence and absence of inhibition by S-modulin at various timings of ATP addition. The results suggested the following in situ mechanism of S-modulin action. After light-activation of rhodopsin kinase, the S-modulin/Ca2+ complex binds to the activated kinase and inhibits the phosphorylation of rhodopsin. The complex, however, does not affect the overall kinetics of the phosphorylation. The inhibition of the kinase by S-modulin is reversible in terms of the Ca2+ concentration. On the other hand, the kinase activity decreases as a function of time, probably via autophosphorylation.

Apoptosis of murine hepatocytes induced by high doses of galactosamine

Apoptosis induced by high doses of Galactosamine (GalN) was investigated in mice hepatocytes in vivo. In mice intraperitoneally (i.p.) treated with GalN 3 g/kg, the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-positive cells were first observed at 6 hr postadministration (PA). Both acidophilic bodies in hematoxylin and eosin (HE)-stained sections and TUNEL-positive cells were markedly found at 24 hr PA. At 48 hr PA, cellular degeneration and necrosis of hepatocytes were prominently observed, and TUNEL-positive cells were scarcely found. In the mice ip treated with GalN 1.5 g/kg, the lesion was milder than that in those treated with GalN 3 g/kg. Acidophilic bodies and TUNEL-positive cells were scarcely found at 24 hr PA, whereas they were markedly seen at 48 hr PA. In addition, a ladder-like DNA fragmentation pattern by agarose gel electrophoresis was observed most remarkably at 24 hr PA with GalN 3 g/kg and at 48 hr PA with GalN 1.5 g/kg, and less distinctly at 48 hr PA with GalN 3 g/kg. On the other hand, sGOT and sGPT activities increased prominently at 48 hr PA with GalN 3 g/kg. These results suggest that the cell death induced by high dose of GalN may be caused by apoptosis, and subsequently by necrosis in vivo.

Implication of protein kinase C-alpha, delta, and epsilon isoforms in ischemic preconditioning in perfused rat hearts

Ischemic preconditioning is a phenomenon in which one or several cycle(s) of brief ischemia-reperfusion protects the myocardium against the cell injury caused by subsequent prolonged ischemia. Protein kinase C (PKC) inhibitors blunt the cardioprotection arising from ischemic preconditioning. To investigate which PKC isoform is involved in ischemic preconditioning, we identified the PKC isoform that translocates to the membrane fraction by means of immunoblotting with specific antibodies. PKC-alpha, delta, epsilon isoforms all increased in the membrane fraction after three cycles of 3 min ischemia and 5 min reperfusion (ischemic preconditioning) in the perfused rat heart. The ischemic preconditioning significantly improved the recovery of left ventricular developed pressure (LVDP) during reperfusion following 20 min of ischemia. A PKC specific inhibitor, chelerythrine (1.0 microM) blocked the effect of ischemic preconditioning on LVDP recovery and the translocation of PKC-alpha, delta, epsilon isoforms. These data suggest that one or more of these three isoforms of PKC is involved in ischemic preconditioning by phosphorylating membrane proteins.

Galactosamine-induced apoptosis in the primary mouse hepatocyte cultures

Galactosamine (GalN)-induced apoptosis was investigated in cultured hepatocytes from mice. The percentage of fragmented DNA measured by the ELISA method increased in a concentration-dependent manner from the very early stage, i.e. 0.5 hrs, after GalN-exposure. In addition, a ladder-like fragmentation pattern by agarose gel electrophoresis appeared first at 3 hr-exposure to 20 mM GalN, at 6 hr-exposure to 10 mM GalN and at 12 hr-exposure to 5 mM GalN, respectively. On the other hand, cytotoxicity indicated by leakage of lactate dehydrogenase from cultured hepatocytes to culture medium was first detected at 24 hrs after GalN-treatment. Morphologically, formation of blebs and apoptotic bodies was observed from 12 hr-exposure to 20 mM GalN and from 24 hr-exposure to 10 mM GalN, respectively. Thus GalN could induce apoptosis in primary hepatocyte cultures from mice.

Expression of visual and nonvisual opsins in American chameleon

We previously characterized five visual opsin genes of American chameleon (Anolis carolinensis). Here we report its nonvisual opsin gene orthologous to the chicken pineal gland-specific opsin (p-opsin) gene. In the pure-cone American chameleon retina, all visual opsins including rod opsin are expressed. In both pineal and parietal eye, three visual opsins as well as P-opsin are expressed. Although opsins are detected in the pineal glands of a wide variety of vertebrates, Southern analysis suggests that the P-opsin gene is used mainly by birds and reptiles.

Restricted TCR V alpha repertoire in the T cell response to a tolerogenic determinant of type II collagen

Tolerization of B10.RIII mice (H-2r) with i.v.-injected type II collagen (CII) renders the animals resistant to induction of collagen-induced arthritis (CIA). The B10.RIII mouse is of particular interest, in that the T cell determinants that induce tolerance are different from those that induce arthritis. To characterize T cells that react with the tolerogenic determinant and play a role in regulation of arthritis, we have developed a panel of T cell hybridomas reactive with the tolerogenic T cell epitope, CII 607-621. None of the hybrids cross-reacted with either the arthritogenic CII 445-453 or murine CII. As determined by PCR and immunofluorescence, the T cell response to the tolerogenic determinant was oligoclonal, with evident preferential usage of V alpha. Through the analysis of a large panel of T cell hybridomas, preferential usage of V alpha2, J alpha44, J beta2.7, and D beta2.1 was observed. Characterization of T cells reactive with the immunodominant determinant, CII 607-621, responsible for the induction of tolerance should prove important in developing novel therapeutic approaches for the treatment of autoimmune diseases.