Taste sorting and naming: can taste concepts be misrepresented by traditional psychophysical labelling systems?

Japanese and American subjects were required to sort filterpapers, soaked in taste stimuli, into categories that had conceptuallythe same taste. Both Japanese and Americans sorted in the samemanner, indicating similar conceptualization. Taste names weregiven to the taste categories obtained by using the traditional‘four basic taste’ naming system, common in tastepsychophysics. This method was seen to underestimate the numberof categories actually present. This suggests a re-assessmentof current psychophysical taste-naming techniques.     

Twenty-four-hour variations in subcellular structures of rat type II alveolar epithelial cells

Summary Subcellular structures of type II alveolar epithelial cells in the rat lung were analyzed at six evenly spaced times over 24 h (light period: 06.00 h–18.00 h), using a morphometric technique. The cell volumes were maximal at 16.00 h and minimal at 08.00 h. The volume and surface densities of rough endoplasmic reticulum and mitochondria were low during the light period, and high during the dark period. Morphometric parameters of multivesicular bodies did not significantly fluctuate over 24 h, but they increased from 04.00 h to 08.00 h. The volume densities of lamellar bodies increased from 16.00 h to 20.00 h, and decreased from 00.00 h to 08.00 h. The change in numerical densities of lamellar bodies was inversely correlated to that in the volume densities. As shown by electron microscopy, small lamellar bodies predominated at 08.00 h, larger lamellar bodies increasing at 16.00h. Composite bodies often appeared at 08.00 h and 12.00 h. Type II cells thus appear to fluctuate, showing three phases over 24 h: formation, accumulation and secretion of lamellar bodies. In particular, it is noteworthy that the accumulation stage occurs during the resting phase of the rat, whereas the secretion stage occurs during its body-active phase.     

Mg2+-paracrystal formation of tropomyosin as a condensation phenomenon. Effects of pH, salt, temperature, and troponin binding.

Tropomyosin (Tm) paracrystal formation induced by Mg2+ was studied by monitoring increases in light scattering. Paracrystals formed above a critical Tm concentration with lag phases in the time courses at pH 7.5 and 6.0, indicating that condensation polymerization processes are involved. The kinetic data at pH 7.5 reasonably fit a model in which nucleation and elongation are taken into account. The rate and extent of light scattering increased at low [Mg2+] and decreased at high [Mg2+] with a maximum at [Mg2+] = 15 mM, indicating different effects of Mg2+ in the two [Mg2+] ranges. The paracrystals were destabilized by increasing the salt concentration and decreasing the temperature. Mg2+ produces paracrystals at pH 6.0 and pH 7.5 by different kinetic mechanisms. Different Tm intermolecular interactions at the two pH values were indicated by studies of the excimer fluorescence of pyrene-labeled Tm and by effects of salt and temperature on the kinetics. At pH 6.0 Tm more readily formed paracrystals with decreased electrostatic effects. Effects of troponin on Mg2+-paracrystal formation of Tm at the two pH values correlated with the known differences in paracrystal structure when troponin is bound to Tm.     

Existence of a polar digitalis-like factor in mammalian hypothalamus

We were able to partially purify a polar digitalis-like factor from rat and bovine hypothalami based on the capacity to inhibit [3H]ouabain binding to intact human erythrocytes. This factor was characterized in reference to the digitalis-like factor that we have isolated and reported on. Hypothalamic factor shared digitalis-like activities and physicochemical properties with the one derived from human urine and mammalian plasma. These findings strongly suggest that a polar digitalis-like factor identical to the circulatory factor does exist in mammalian hypothalamus.     

Stress fibers in the mesenteric mesothelial cells of the large intestine of the bullfrog,Rana catesbeiana

Summary Actin-containing cytoplasmic fibers were visualized in the mesenteric mesothelial cells of the large intestine of bullfrog tadpoles by rhodamine-phalloidin staining of en face preparations of mesothelial cells. These fibers were concurrently stained by immunofluorescence using antibodies to myosin or -actinin. Electron microscopy showed the presence of bundles of microfilaments in the basal cytoplasm of the cells. Such fibers in the mesothelial cells may be comparable to the stress fibers present in cultured cells. The mesothelial cells initially formed axially oriented stress fibers when they changed from a rhombic to a slender spindle-like shape. On the other hand, stress fibers disappeared as cells transformed from elongated to polygonal shapes during the period of metamorphic climax. Expression of stress fibers in these cells appears to be related to the degree of tension loaded on the mesentery, which may be generated by mesenteric winding. These stress fibers in the mesothelial cells may serve to regulate cellular transformation. They may also help to maintain cellular integrity by strengthening the cellular attachment to subepithelial tissue against tensile stress exerted on the mesentery.     

Increased renal TXA2 synthesis in diabetes mellitus: simultaneous determination of urinary TXB2 and 2,3-dinor-TXB2

The present study was designed to determine urinary excretion of kallikrein(KAL)-kinin as well as prostaglandin (PG) E2, TXB2 and 2,3-dinor-TXB2, a major urinary metabolite of TXA2 synthesized in platelets, by specific RIAs in patients with diabetes mellitus (DM). KAL or kinin excretion in 26 type II DM did not differ from control values obtained in 18 age-matched healthy subjects (C), although DM with HbA1 greater than 11% excreted less KAL. Urinary PGE2 excretion (7.6 +/- 2.8 ng/mg creatinine, mean +/- SE) was significantly lower in DM compared to C (17.5 +/- 3.9, p less than 0.05), while DM excreted more TXB2 (0.57 +/- 0.09, p less than 0.01) and 2,3-dinor-TXB2 (0.56 +/- 0.12, N.S.) than C (0.19 +/- 0.02 or 0.33 +/- 0.01). DM with or without mild proteinuria demonstrated lower PGE2, but higher TXB2 and 2,3-dinor-TXB2 excretion. A positive correlation of TXB2/2,3-dinor-TXB2 with proteinuria was observed in this group. However, in DM with massive proteinuria over 500 micrograms/mg creatinine, TXB2 and 2,3-dinor-TXB2 excretion decreased to levels almost identical to C. As a whole, a ratio of TXB2 to PGE2 or 2,3-dinor-TXB2 in DM was significantly higher than in C. The results suggest that a relative preponderance of TXB2 to 2,3-dinor-TXB2 may indicate an augmented renal, in addition to platelet, TXA2 synthesis. An excessive vasoconstrictive and proaggregatory TXA2 renal synthesis, concomitant with a decrease in vasodilatory and antiaggregatory PGE2, may have profound effects on renal functions such as protein excretion in DM.     

Immunocytochemical studies on the pituitary pars distalis of the Japanese long-fingered bat,Miniopterus schreibersii fuliginosus

Summary Immunocytochemical studies were performed to describe the characteristics of cell types and their distribution in the pars distalis of Japanese long-fingered bat, Miniopterus schreibersii fuliginosus, collected at various stages of the reproductive cycle. Six distinct cell types have been identified in the pars distalis by the unlabeled immunoperoxidase technique and by the ABC method. Growth hormone (GH) and prolactin (PRL) cells were immunostained with antisera against chicken GH and ovine PRL. The GH-immunoreactive cells were round or oval orangeophilic cells distributed throughout the pars distalis with prominent aggregation in the posterolateral region. The PRL cells were pleomorphic carminophilic cells that occurred in small groups within the central and dorsocaudal regions of the pars distalis. They were sparsely distributed in the central region of the pars distalis in the hibernating bats, but increased significantly in the pregnant and lactating bats. The adrenocorticotropic (ACTH) cells were large round or polygonal amphophilic cells in the rostroventral and ventrolateral regions of the pars distalis. The thyrotropic (TSH) cells were small rounded or polygonal and distributed mainly in the ventrolateral region of the pars distalis. Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) cells were identified immunocytochemically with antisera against the specific beta subunits of ovine LH and rat FSH. There were two populations of LH and FSH cells, one aggregated in the zona tuberalis and the other scattered singly throughout the rest of the pars distalis. The aggregated cells were immunoreactive with both antisera directed to LH and FSH, while scattered cells were reactive solely with antiserum to either LH or FSH and exhibited seasonal variations. In females, the proportional volume of the pars distalis occupied by LH cells was significantly reduced during pregnancy and lactation. No evidence of involution was observed in pars distalis cells except for PRL cells in males or females during hibernation.     

Selective inhibition of high- but not low-affinity interleukin 2 binding by lectins and anti-interleukin 2 receptor alpha antibody

The present study demonstrated that various reagents can specifically reduce the affinity of high-affinity interleukin 2 receptor (IL-2R) but not that of low-affinity IL-2R. They included lectins such as wheat germ agglutinin (WGA), concanavalin A and phytohemagglutinin, and a chemical cross-linker, glutaraldehyde, in addition to anti-IL-2R monoclonal antibodies, HIEI and H-47. The affinity of the high-affinity IL-2R was reduced when the cells were treated with WGA or H-47 before, but not after, addition of 125I-labeled interleukin 2 (IL-2). Their inhibitory effects were also demonstrated by the chemical cross-linking method. On treatment with the reagents, the IL-2 binding to both IL-2R alpha and beta chains was inhibited and these inhibitory effects were seen only when the reagents were added before IL-2 addition, like their high-affinity reducing effects. These results support a supposition that the high affinity IL-2R is generated by assembly of the alpha and beta chains, and suggest that the IL-2 binding to IL-2R alpha and beta chains could induce stable constitution of the high-affinity state of IL-2R, but these affinity modulating reagents could perturb the optimum association between alpha and beta chains to generate the high-affinity IL-2R.     

A novel function of glutamine in cell culture: utilization of glutamine for the uptake of cystine in human fibroblasts

Transport and metabolism of glutamine has been investigated in human diploid fibroblasts, IMR-90. Glutamine was taken up via System ASC (Na+-dependent amino acid transport system especially reactive with short or polar side chain amino acids). In the routine culture medium the cells contained a large quantity of glutamate; its major source was shown to be glutamine in the medium. Previously we described a transport system that mediates the entrance of cystine in exchange for the exit of glutamate (Bannai, 1986). Since the cystine taken up is reduced to cysteine and the cysteine readily exits to the medium where it is oxidized to cystine, a cystine-cysteine cycle across the plasma membrane has been postulated. When the cells were cultured in glutamate/glutamine-free medium, intracellular glutamate decreased, depending on the amount of cystine in the medium; in the absence of cystine, glutamate decreased very slowly. When the cells were cultured in ordinary medium, glutamine in the medium decreased, and glutamate in the medium increased. Both changes were well correlated with cystine concentration in the medium. These results are consistent with the view that the intracellular glutamate, of which the source is glutamine in the medium, is released from the cells into the medium in order to take up cystine and thereby to rotate the cystine-cysteine cycle. In the routine culture one-third to one-half of the total consumption of glutamine seems to be used for the uptake of cystine.