Erratum: Quadrupole Order in the Frustrated Pyrochlore Tb_{2+x}Ti_{2-x}O_{7+y} [Phys. Rev. Lett. 116, 217201 (2016)].

This corrects the article DOI: 10.1103/PhysRevLett.116.217201.

Quadrupole Order in the Frustrated Pyrochlore Tb_{2+x}Ti_{2-x}O_{7+y}.

A hidden order that emerges in the frustrated pyrochlore Tb_{2+x}Ti_{2-x}O_{7+y} with T_{c}=0.53 K is studied using specific heat, magnetization, and neutron scattering experiments on a high-quality single crystal. Semiquantitative analyses based on a pseudospin-1/2 Hamiltonian for ionic non-Kramers magnetic doublets demonstrate that it is an ordered state of electric quadrupole moments. The elusive spin liquid state of the nominal Tb_{2}Ti_{2}O_{7} is most likely a U(1) quantum spin-liquid state.

Effects of halothane on GABAergic and glutamatergic transmission in isolated hippocampal nerve-synapse preparations.

We evaluated the effects of halothane on synaptic and extrasynaptic GABA(A) and glutamate receptor responses using mechanically dissociated rat hippocampal CA3 neurons in which the well isolated neurons retain functional native nerve endings (the 'synaptic bouton' preparation). The preparation allows the simultaneous comparison of extrasynaptic GABA(A) and glutamate receptors, activated by bath applied GABA and glutamate, respectively, to the synaptic receptors measured as spontaneous and evoked postsynaptic currents. Paired-pulse synaptic responses evoked by focal electrical stimulation were also measured to evaluate any presynaptic effects. Halothane enhanced the extrasynaptic GABA(A)-receptor mediated postsynaptic responses in a concentration dependent fashion. At clinically relevant concentrations, halothane significantly increased both the amplitude and frequency of spontaneous postsynaptic inhibitory currents (sIPSCs) mediated by synaptic GABA(A) receptors. The relative amplitude of evoked IPSCs (eIPSCs) was also increased, concurrent with a decrease in failure rate and a significantly decreased eIPSC paired-pulse ratio. Halothane concentration dependently decreased the extrasynaptic glutamate-receptor induced postsynaptic responses but had no effects on spontaneous or evoked excitatory postsynaptic currents. These results suggest that halothane acts predominantly at presynaptic sites at GABAergic synapses to enhance inhibitory transmission at CA3 synapses, although it also increases extra-synaptic GABA responses. At excitatory synapses on to CA3 neurons, halothane has no presynaptic action-effecting only extrasynaptic receptors. Our results have clarified the locus of effects of the volatile anesthetic halothane at excitatory and inhibitory synapses, drawing somewhat different conclusions from those deduced from slices and culture systems.

An immunohistochemical study of the attachment mechanisms in different kinds of adhesive interfaces in teeth and alveolar bone of the rat.

BACKGROUND AND OBJECTIVE: This study was designed to examine the histological and immunohistochemical nature of different kinds of adhesive interfaces in the rat molar region under identical experimental conditions and to discuss the structural and functional similarities between these adhesive interfaces. MATERIAL AND METHODS: Four kinds of adhesive interfaces - an initial attachment layer for principal fibers on the developing alveolar bone surface, a reattachment layer for principal fibers on resorbed alveolar bone surface, cement lines on the alveolar bone surface unrelated to the principal fibers, and the cemento-dentinal junction - were examined in 25-d-old male Wistar rats. Routine histological staining, immunohistochemical staining for bone sialoprotein and osteopontin, and digestion tests with trypsin were conducted. RESULTS: The adhesive interfaces showed very similar histological and immunohistochemical features: they were intensely hematoxylin-stainable, deficient in collagen fibrils, and rich in bone sialoprotein and osteopontin. After trypsin treatment the four adhesive interfaces had lost immunoreactivity to bone sialoprotein and osteopontin, and the two adjacent tissue parts held together finally separated at the adhesive interfaces. CONCLUSION: The above findings suggest that (i) the different types of adhesive interfaces in the rat molar region have a common structure in that they are filled with highly accumulated bone sialoprotein and osteopontin and deficient in collagen fibrils; (ii) accumulated bone sialoprotein and osteopontin are closely associated with the adhesion at the interfaces; and (iii) the adhesive interfaces have a similar developmental process.

Biological behavior of myoepithelial cells in the regeneration of rat atrophied sublingual glands following release from duct ligation.

The present study aimed to clarify how myoepithelial cells behave during regeneration of an atrophied sublingual gland by investigating cell proliferation and ultrastructure. Atrophy of rat sublingual glands was induced by unilateral ligation of the excretory duct near the hilum with metal clips, which were then removed after one week of ligation for regeneration. The sublingual glands 0-14 days after unligation were examined with single immunohistochemistry for actin as a marker of myoepithelial cells, double immunohistochemistry for actin and proliferating cell nuclear antigen (PCNA) as a marker of proliferating cells, and transmission electron microscopy (TEM). The single immunohistochemistry and TEM showed that myoepithelial cells surrounded residual ducts in the atrophied glands and immature and mature acini in the regenerating glands. Although PCNA-positive myoepithelial cells were identified during regeneration, PCNA labeling indices of myoepithelial cells were low at all time points except at day 7. Ultrastructurally, myoepithelial cells showing bizarre shaped structures in the atrophy changed with maturation of differentiating acinar cells and appeared normal in the regenerated glands. There was no differentiation of the remaining duct cells to myoepithelial cells. These observations suggest that proliferation of myoepithelial cells and differentiation to myoepithelial cells do not commonly participate in the regeneration of atrophied sublingual glands and that the bizarre shaped myoepithelial cells in the atrophied sublingual glands recover the original shapes with acinar cell regeneration.

Functional MRI detection of activation in the primary gustatory cortices in humans.

Magnetoencephalography (MEG) has recently revealed that the transitions between the parietal operculum (Pop) and the insula (area G) and the ventral end of the central sulcus (cs) were activated with the shortest latency by instrumental gustatory stimulation, which suggests that the location of the primary gustatory area is in these two regions. However, studies using other noninvasive brain-imaging methods such as positron-emission tomography or functional magnetic resonance imaging (fMRI) with manual application of tastants into the mouth have been unable to confirm this. The present study examined cortical activation by repetitive stimulation of the tongue tip with 1 M NaCl with a computer-controlled stimulator and used fMRI to detect it. In individual brains, activations were detected with multiple comparisons (false discovery rate) across the whole brain corrected (threshold at P < 0.05) at both area G and frontal operculum (Fop) in 8 of 11 subjects and at the rolandic operculum (Rop) in 7 subjects. Activations were also found at the ventral end of the cs (n = 3). Group analysis with random-effect models (multiple comparison using familywise error in regions of interest, P < 0.02) revealed activation at area G in both hemispheres and in the Fop, Rop, and ventral end of the cs on the left side. The present study revealed no activation on the gyrus of the external cerebral surface except for the Rop. Taking MEG findings into consideration, the present findings strongly indicate that the primary gustatory area is present at both the transition between the Pop and insula and the Rop including the gray matter within a ventral part of the cs.

Determination of two different types of cellular cementogenesis in rat molars: a histological and immunohistochemical study.

To elucidate the attachment mechanism of dentin and cellular cementum, developing and developed cellular cementum of rat molars was examined by light microscopy. Routine histological staining, immunohistochemical staining for bone sialoprotein (BSP) and osteopontin (OPN), and digestion tests with trypsin were conducted. Two different types of cellular cementogenesis were established, one on the mesial (type I cementogenesis) and one on the distal sides (type II cementogenesis) of the examined roots. In the type I cementogenesis a thin initial cementum layer, which was fibril-poor, hematoxylin-stained, and immunopositive for BSP and OPN, appeared on the mineralized dentin. With cellular cementogenesis, the layer became the cemento-dentinal junction. The cementum mineralization did not precede the dentin mineralization. After trypsin treatment the cemento-dentinal junction lost immunoreactivity for BSP and OPN and the cementum was detached from the dentin. In the type II cementogenesis the cellular cementum formed directly on the predentin without the initial cementum layer and the cementum mineralization preceded the dentin mineralization. Cemental and predentinal fibrils appeared to intermingle, as the cemento-dentinal junction was indiscernible by any staining. Trypsin treatment did not cause cementum detachment. The findings of the present study suggest that: (1) The type I cementogenesis requires the intervening initial cementum to bind cementum and dentin and to induce the cementum mineralization. (2) In the type II cementogenesis the cemento-dentinal attachment depends on fibril intermingling and the cementum mineralization advances apically and very rapidly, probably producing mineralization foci. (3) The formation of the initial cementum depends on the speed of the cementogenesis in the apical direction.

Active participation of apoptosis and mitosis in sublingual gland regeneration of the rat following release from duct ligation.

This study was designed to establish how mitotic cell proliferation and apoptotic cell death participate in the regeneration of atrophied rat sublingual glands. To induce atrophy to the sublingual gland of rats, the excretory duct was ligated unilaterally near the hilum, and after 1 week of ligation (day 0) the duct ligation was released to enable gland regeneration. The regenerating glands were examined with routine histology, immunohistochemistry for proliferating cell nuclear antigen (PCNA) as a marker of proliferating cells, terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling (TUNEL) as a marker of apoptotic cells, and transmission electron microscopy. At day 0, a few acini and many ducts remained in the atrophic sublingual glands, and newly formed immature acini were observed at day 3. Thereafter acinar cells progressively matured and increased in number, although the number of ducts decreased. Many PCNA- and some TUNEL-positive cells were seen in acini and ducts during regeneration. The labeling indices for both cell types were statistically significantly different from that of the control at several time points of the regeneration. Apoptotic and mitotic cells were also confirmed to be present in the experimental sublingual glands by electron microscopy. These observations suggest that apoptosis as well as mitosis of duct and acinar cells actively participate in and play important roles in sublingual gland regeneration.

Immunohistochemical characterization of noncollagenous matrix molecules on the alveolar bone surface at the initial principal fiber attachment in rat molars.

This study was designed to immunodetect proteoglycans (PGs) and the noncollagenous glycoproteins, bone sialoprotein (BSP) and osteopontin (OPN) on developing alveolar bone surface in rat molars by the indirect immunoperoxidase method, and to discuss the roles of these molecules at the initial principal fiber (PF) attachment. To characterize PGs, antibodies against five species of glycosaminoglycans (GAGs), chondroitin-4-sulfate (C4S), chondroitin-6-sulfate (C6S), unsulfated chondroitin (C0S), dermatan sulfate (DS), and keratan sulfate (KS) were used. Maxillary alveolar bone facing the distal root of the second molar was examined in 20- and 25-day-old male Wistar rats. Routine histological staining was also used. A hematoxylin-stained, fibril-poor layer always appeared on the alveolar bone surface just prior to the initial PF organization. This layer was strongly immunoreactive for C4S, C0S, OPN, and BSP, and weakly for C6S, but not for DS and KS. Then the initial PFs were attached to this layer. When new bone containing Sharpey's fibers covered this layer, it remained as a hematoxylin-stained, fibril-poor layer between Sharpey's fiber-containing and -lacking bone. The layer was consistently immunoreactive for OPN and BSP but had no immunoreactivity for GAGs. The results suggest that the accumulation of C4S-, C0S-, and C6S-carrying PGs, and of BSP and OPN is a primary event at the initial PF attachment, and is involved in the adhesion of PFs and mineralization of the initial attachment layer. The BSP and OPN act to maintain the interface integrity between Sharpey's fiber-containing and Sharpey's fiber-lacking alveolar bone after the PF attachment is established.

Immunolocation of proteoglycans and bone-related noncollagenous glycoproteins in developing acellular cementum of rat molars.

To elucidate the roles of proteoglycans of (PGs), bone sialoprotein (BSP), and osteopontin (OPN) in cementogenesis, their distribution was investigated in developing and established acellular cementum of rat molars by an immunoperoxidase method. To characterize PGs, antibodies against five species of glycosaminoglycans (GAGS), chondroitin-4-sulfate (C4S), chondroitin-6-sulfate (C6S), unsulfated chondroitin (C0S), dermatan sulfate (DS), and keratan sulfate (KS) were used. Routine histological staining was also applied. With onset of dentin mineralization, the initial cementum appeared on the dentin surface as a hematoxylin-stained fibril-poor layer. Subsequently, primitive principal fibers attached to the initial cementum. As the acellular cementum containing extrinsic fibers covered the initial cementum, the intal cementum formed the cemento-dentinal junction. Following immunohistochemistry at the earliest time of cementogenesis, the initial cementum was intensely immunoreactive for C4S, C6S, C0S, BSP, and OPN. After the initial cementum was embedded, neither the cemento-dentinal junction nor the cementum was immunoreactive for any GAG species. However, the cementum was immunoreactive for any GAG species. However, the cementum and cemento-dentinal were consistently immunoreactive for BSP. Although the cemento-dentinal junction was consistently immunoreactive for OPN, the remaining cementum showed no significant immunoreactivity. Thus, initial acellular cementogenesis requires a dense accumulation of PGs, BSP, and OPN, which may be associated with the mineralization process independently of collagen fibrils and initial principal fiber attachment.

Mitotic proliferation of myoepithelial cells during regeneration of atrophied rat submandibular glands after duct ligation.

BACKGROUND: The purpose of the present study was to elucidate whether myoepithelial cells proliferate mitotically during regeneration of rat submandibular glands after atrophy. METHODS: The excretory duct of the right submandibular gland of rats was doubly ligated near the hilum with metal clips, which were removed after 7 days of ligation (day 0). The regenerating right submandibular glands were removed from 0 to 14 days after removal of the clips. The removed tissue was examined with immunohistochemical double staining for proliferating cell nuclear antigen (PCNA) as a marker of proliferating cells and actin as a marker of myoepithelial cells, as well as with transmission electron microscopy (TEM). RESULTS: The PCNA-positive myoepithelial cells were observed at the periphery of transitional duct-acinar structures, ducts and acini in the regenerating glands at every time-point, and the PCNA-labeling index of myoepithelial cells increased greatly especially between day 2 and 4. The mitosis of myoepithelial cell was also identified by TEM at day 4. CONCLUSION: These findings suggest that myoepithelial cells are able to proliferate mitotically during regeneration of rat submandibular gland.

Prenatal development of the palatine gland of rats.

The present study aimed to elucidate the prenatal development of the rat palatine gland. Parasagittal 5 microm thick serial sections made from Wistar rats at embryonic days (E) 17 to 22 were stained with haematoxylin-eosin (HE), Alcian blue-Kernechtrot or immunohistochemistry for 5-bromo-2'-deoxyuridine (BrdU) as a marker of proliferating cells. Additionally, three-dimensional images of developing glandular parenchyma were reconstructed from serial HE sections with a personal computer. At E 17, several thickenings of the palatal epithelium had appeared which thereafter became the epithelial cords. Branching and lumenization commenced at E 20, and immature acini were observed at E 21. Three-dimensional reconstruction showed that the proximal part of the epithelial cord differentiated into the duct, and the distal part of the epithelial cord differentiated into the acinus. In immunohistochemical staining, there were many BrdU-positive cells in the epithelial cords including thickenings of the palatal epithelium, ducts, and acini. The BrdU labeling index of the cells of the epithelial cord was the highest (statistically significant) of the three in the primitive palatine gland. In conclusion, during the development of the rat palatine gland, epithelial cords with very high proliferative activity arise from the palatal epithelium, and then the proximal part of the epithelial cord differentiates into the duct, and the distal part of the epithelial cord differentiates into the acinus. Proliferation of these glandular parenchyma contributes to the growth of the developing palatine gland.

Cell death and cell proliferation in the regeneration of atrophied rat submandibular glands after duct ligation.

BACKGROUND: The present study aimed to clarify the proliferation and apoptosis of parenchymal cells during regeneration of rat submandibular glands following atrophy. METHODS: Atrophy of the right submandibular gland of rats was induced by excretory duct ligation at the hilum with metal clips, which were removed 1 week (day 0) after ligation. The right submandibular glands were collected from 0 to 14 days after removal of the clips and investigated using immunohistochemistry for proliferating cell nuclear antigen (PCNA) as a marker of proliferating cells, terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-digoxigenin nick end labeling (TUNEL) as a marker of apoptotic cells, and transmission electron microscopy (TEM). RESULTS: After 1 week of ligation, there were many remaining ducts and a few acini in the atrophic glands. At day 3 after discontinuing the ligation, newly formed acini appeared and thereafter increased in number and maturity. Many residual and newly formed acinar cells showed positive reaction to PCNA especially at days 4 and 5. The PCNA-positive duct cells decreased in number with the regeneration. A few TUNEL-positive acinar and duct cells were identified during regeneration. Mitosis and apoptosis of parenchymal cells were also identified by TEM. CONCLUSIONS: During regeneration of the submandibular gland after atrophy, both residual and newly formed acinar cells proliferate actively. There is also apoptosis of parenchymal cells; however, the significance of apoptosis is low.

The reaction of osteoclasts when releasing osteocytes from osteocytic lacunae in the bone during bone modeling.

Osteocytes are released from the osteocytic lacunae when osteoclasts resorb the bone matrix during bone modeling and remodeling. It remains unknown how osteoclasts react when releasing osteocytes during bone modeling, and the fate of these released osteocytes is also unclear. Femoral mid-shafts of 2-day-old kittens were sectioned into serial 0.5 microm-thick semithin or 0.1 microm-thick ultrathin sections, and examined by light microscopy (LM) and transmission electron microscopy (TEM). The sections showed many osteoclasts at the endosteum but there were no osteoblasts. There were many half-released, fully released, half-exposed, and fully exposed osteocytes on the bone surfaces. Many cell-like structures were seen in the cell bodies of osteoclasts by LM, and some semithin sections were re-sectioned into ultrathin sections for re-observation by TEM. By TEM, these were determinated to be mononuclear cells. The serial ultrathin sections showed that the mononuclear cells appeared to be engulfed in osteoclasts on one section but that the cell was connected with the bone surface of the osteocytic lacuna on another section. These results show that the mononuclear cells in the osteoclasts were osteocytes. The present study suggests that osteoclasts engulf some osteocytes but do not engulf others when releasing osteocytes during bone modeling.

Tissue distribution of prolactin receptor mRNA during late stage embryogenesis of the chick.

Serum prolactin increases during late embryogenesis. In order to elucidate the function of prolactin at this period, tissue distribution of prolactin receptor mRNA was examined by RNase protection assay. The mRNA was detected strongly in the kidney, intestine, and allantoic membrane; weakly detected in the brain; but not detected in the liver. The expression levels of the prolactin receptor mRNA in the kidney, intestine, and allantoic membrane were retained at constant levels during later stages of embryogenesis (Days 17 and 19) and posthatch periods (2 and 28 d after hatching). These results suggest that prolactin is mainly involved in the osmoregulation during the later stage of embryogenesis and that the expression of prolactin receptor mRNA in the kidney, intestine, and allantoic membrane is regulated by a serum prolactin-independent manner.

Proliferation and distribution of myoepithelial cells during atrophy of the rat sublingual gland.

BACKGROUND: The present study was aimed to determine the proliferation and distribution of myoepithelial cells during atrophy of rat sublingual glands. METHODS: The excretory duct of the right sublingual gland of rats was doubly ligated with metal clips to induce atrophy in the gland. The atrophic sublingual glands were taken from 1 to 28 days after duct ligation and examined with single immunohistochemistry for actin as a marker of myoepithelial cells and with immunohistochemical double staining for actin and proliferating cell nuclear antigen (PCNA) as a marker of proliferating cells. RESULTS: In unligated sublingual glands, myoepithelial cells embraced acini and intercalated ducts, but not striated and interlobular excretory ducts. In the early stages of atrophy, myoepithelial cells surrounded small ducts but not large ones. However, in the later stages of atrophy, myoepithelial cells were also observed at the periphery of the large ducts. The immunohistochemical double staining showed that there were PCNA-positive myoepithelial cells in the normal as well as in the atrophic sublingual glands. However, the PCNA labeling indices of myoepithelial cells were low in the unligated and atrophic sublingual glands, and there were no statistically significant differences in these labeling indices. CONCLUSION: The observations suggest that the distribution of myoepithelial cells change during atrophy of rat sublingual glands and that myoepithelial cells have low proliferative activity in both the normal and atrophic condition of rat sublingual glands.

Isolated medial medullary infarction due to vertebral artery dissection.

A 54-year-old man developed left hemiparesis and tactile and deep sensory disturbance following onset of rightside cervical pain. These symptoms resulted from an isolated infarct in the right medial area of the upper medulla oblongata and intracranial vertebral artery (VA) dissection. Atherosclerotic disease of the VA is the most common cause of medial medullary infarction. In past reports of isolated medial medullary infarction, only a few cases involved VA dissection.

The roles of apoptosis and mitosis in atrophy of the rat sublingual gland.

The roles of apoptosis and mitosis of acinar and duct cells in the atrophy of the sublingual gland of rat induced by double duct ligation was investigated using immunohistochemistry for proliferating cell nuclear antigen (PCNA), terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-digoxigenin nick end labeling (TUNEL), and transmission electron microscopy (TEM). Many PCNA-positive duct cells were observed 3 days after duct ligation, and the numbers decreased thereafter. At 3 and 5 days, several TUNEL-positive acinar cells were observed and typical apoptotic acinar cells were identified by TEM. Necrotic acinar cells were also observed ultrastructurally. After 7 days, there were few acini but many ducts, as well as many structures representing transition from acinus to duct. These observations demonstrate that acinar cell loss by apoptosis and duct cell proliferation by mitosis occur in atrophic sublingual glands as well as in other atrophic salivary glands. In addition, it appears that the transition from acinar to duct cell and the necrosis of acinar cells play important roles in the atrophy of the sublingual gland.

Three-dimensional distribution of the clear zone of migrating osteoclasts on dentin slices in vitro.

Osteoclasts are cells that dynamically alternate resorption and migration on bone surfaces, and have the special structure called ruffled borders and clear zones by transmission electron microscopy (TEM). However, TEM features, especially the distribution of the clear zone of osteoclasts during migration, remains unclear. This study aimed to examine osteoclasts cultured on dentin slices by TEM and clarify the features of migrating osteoclasts, especially the three-dimensional distribution of clear zones. Osteoclasts obtained from mice were cultured with dentin slices for 72 h, and then cells were fixed and the tartrate-resistant acid phosphatase (TRAP) activity was detected. Specimens were embedded in Epon, then TRAP-positive cells were serially sectioned by alternating semithin and ultrathin sections. The cells were examined by TEM and the three-dimensional structures were reconstructed by computer. By TEM, most TRAP-positive cells were resorbing osteoclasts with ruffled borders and a clear zone. There were osteoclasts without ruffled borders, and these cells had clear zone-like structures and lamellipodia. The three-dimensional reconstruction showed that resorbing osteoclasts had rounded contours and ring-shaped clear zones encircling ruffled borders, and that osteoclasts without ruffled borders had irregular and flat shapes; the clear zone-like structures showed a dot or patch-like distribution. The presence of lamellipodia of the osteoclasts without ruffled borders shows that the cells are migrating osteoclasts. These results suggest that dot or patch-like distribution is the feature of the clear zone of osteoclasts during migration, and that these structures play the role of focal contacts and adhesion to the dentin surfaces during cell migration.