Dexmedetomidine is safe and effective for reducing intraprocedural pain in colorectal endoscopic submucosal dissection

Objectives

Endoscopic submucosal dissection (ESD) is effective for the resection of colorectal intramucosal lesions. This study was performed to examine the safety and effectiveness of using dexmedetomidine (DEX) in the anesthesia regimen of patients with colorectal lesions undergoing ESD.

Methods

We retrospectively examined 287 consecutive patients who underwent ESD for colorectal lesions in our institution from January 2015 to December 2021. Outcomes including the frequency of intraprocedural pain and adverse events were compared between the DEX and no DEX groups. Moreover, univariate and multivariate analyses were conducted for each clinical factor of intraprocedural pain. Intraprocedural pain was defined as patient-reported abdominal pain or body movement during the procedure.

Results

The incidence of intraprocedural pain was significantly lower in the DEX than in the no DEX group (7% vs. 17%, p = 0.02). The incidence of hypotension was also significantly higher in the DEX group (7% vs. 0%, p = 0.01), but no cerebrovascular or cardiac ischemic events occurred. In the univariate analyses, the diameter of the resected specimen, procedure time, no use of DEX, and total midazolam dose was associated with intraprocedural pain. The midazolam dose and DEX administration were significantly negatively correlated and the diameter of resected specimen and procedure time were significantly positively correlated. Multivariate logistic regression showed that no use of DEX was independently associated with intraprocedural pain (p = 0.02).

Conclusions

Adding DEX to the anesthesia regimen in patients undergoing colorectal ESD appears to be safe and effective for reducing intraprocedural pain.

Two cases of esophageal basaloid squamous cell carcinoma which achieved long-term survival by endoscopic submucosal dissection and additional chemoradiotherapy

Herein, we report two rare basaloid squamous cell carcinoma (BSCC) cases. Esophagogastroduodenoscopy revealed a submucosal tumor-like lesion and a biopsied specimen showed a finding suspected of BSCC in both cases. Both lesions underwent endoscopic submucosal dissection with en bloc resection, and long-term survival was achieved using additional chemoradiotherapy. The standard treatment for BSCC has not been determined, and there are few reports of esophageal BSCC treated using endoscopic resection. Endoscopic submucosal dissection and additional chemoradiotherapy for superficial BSCC may be effective treatment options.

Longly-attached cap can contribute to en bloc underwater endoscopic mucosal resection of 20-30 mm colorectal intramucosal lesions

Background and study aims  Underwater endoscopic mucosal resection (UEMR) is effective for colorectal intramucosal lesions. The aim of this study was to evaluate whether a longly-attached cap in UEMR improves the en bloc resection rate for 20-30 mm lesions. Patients and methods  We performed a retrospective study at a tertiary institute. Candidates for the study were systematically retrieved from an endoscopic and pathological database from October 2016 to December 2020. We assessed the procedural outcomes with UEMR for lesions ≥ 20 mm in size and the clinical factors contributing to en bloc resection. Results  A total of 52 colorectal lesions that underwent UEMR were included. The median procedure time was 271 (66-1264) seconds. The en bloc resection rate and R0 resection rate were 75 % and 73 %, respectively. Intraprocedural perforation occurred in one (1.9 %) case, but no bleeding occurred. Delayed bleeding occurred in one (1.9%) case, but no delayed perforation occurred. Regarding tumor size, macroscopic type, tumor location, and the presence or absence of a history of abdominal operation, there was no significant difference between the en bloc resection and piecemeal resection groups. The visibility of the whole lesion, a longly-attached cap, and sessile serrated lesions were more frequently observed in the en bloc resection group than in the piecemeal resection group ( P  < 0.001, P  = 0.01, and P  = 0.04, respectively). Multivariate analysis showed that a longly-attached cap was the only independent factor associated with en bloc resection ( P  = 0.02). Conclusions  A longly-attached cap might contribute to en bloc resection.

Association between antispasmodics and detection of lesions by screening esophagogastroduodenoscopy

Background and Aim

Whether administration of antispasmodics as a component of premedication contributes to detection of lesions by screening esophagogastroduodenoscopy (EGDS) remains unclear. Our primary aim was to investigate this possibility.

Methods

The cohort in this retrospective study comprised consecutive asymptomatic individuals who had undergone screening EGDS as part of a health check‐up at the Japanese Red Cross Wakayama Medical Center from October 2015 to September 2020. The investigated lesions comprised esophageal squamous cell carcinoma or adenocarcinoma, gastric adenoma or adenocarcinoma, and duodenal adenoma or adenocarcinoma.

Results

Targeted lesions were detected in 72 of 31 484 participants (0.23%), 18 260 and 13 224 of whom had received and not received pre‐procedure antispasmodics, respectively. The rates of detection of lesions in these groups were 0.21% (38/18260) and 0.26% (34/13224), respectively (P = 0.40). Multivariate logistic regression analysis showed no association between administration of antispasmodics and rates of detection of targeted lesions [P = 0.24, Odds ratio (95% CI): 1.46 (0.78–2.75)].

Conclusions

Antispasmodics, which were administered to more than half of the study cohort, did not improve the rate of detection of targeted lesions.

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.

Pigeons' discrimination of paintings by Monet and Picasso

Pigeons successfully learned to discriminate color slides of paintings by Monet and Picasso. Following this training, they discriminated novel paintings by Monet and Picasso that had never been presented during the discrimination training. Furthermore, they showed generalization from Monet's to Cezanne's and Renoir's paintings or from Picasso's to Braque's and Matisse's paintings. These results suggest that pigeons' behavior can be controlled by complex visual stimuli in ways that suggest categorization. Upside-down images of Monet's paintings disrupted the discrimination, whereas inverted images of Picasso's did not. This result may indicate that the pigeons' behavior was controlled by objects depicted in impressionists' paintings but was not controlled by objects in cubists' paintings.

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.

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.

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.

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.

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.

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.

Immunolocalization 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.

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.

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 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.

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.

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.

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.

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.

Postnatal growth of the rat palatine gland

To elucidate how the palatine glands grow postnatally, the palatine glands of rats from 0 to 8 weeks of age were investigated histologically and immunohistochemically. Under light microscope, three dimensions of the right part of the palatine glands were measured and the total number of excretory ducts of the glands was counted from the parasagittal serial sections. Immunohistochemistry with anti-5-bromo-2'-deoxyuridine (BrdU) monoclonal antibody was also employed to detect the cellular proliferative activity. At birth (0 weeks), the palatine glands consisted of ducts and immature acini. The ducts in the glands were connected with excretory ducts. After 2 weeks, there was no duct in the glands. Most acinar cells became mature as mucous cells and took the form of tubulo-acini connected directly with excretory ducts. In the posterior region of the glands, serous acinar cells forming demilunes were occasionally seen. All three dimensions of the palatine glands became longer, and the number of excretory ducts tended to increase. Immunohistochemistry showed acinar and duct cells were highly proliferative in early stage of postnatal life and their proliferative activity decreased thereafter. This study demonstrated that immature rat palatine glands of newborn rats grow three-dimensionally during maturation, and that the parenchymal cell proliferation contributes to the growth of the rat palatine glands. In addition, it is suggested that the glandular tissue arises from the excretory ducts formed postnatally.

Apoptosis and proliferation of myoepithelial cells in atrophic rat submandibular glands

This study was designed to determine whether apoptosis and proliferation of myoepithelial cells occur in atrophic rat submandibular glands. The excretory duct of the right submandibular gland was doubly ligated with metal clips. The atrophic right submandibular glands removed after 1-28 days of duct ligation were investigated using immunohistochemical double staining for actin as a marker for myoepithelial cells and proliferating cell nuclear antigen (PCNA) as a marker for proliferating cells, double staining for actin immunohistochemistry, nick end-labeling (TUNEL) as a marker for apoptotic cells, and transmission electron microscopy (TEM). A few PCNA- and no TUNEL-positive myoepithelial cells were found in the control submandibular glands taken from animals with no operation. In the experimental glands, PCNA-positive myoepithelial cells were common 2 and 3 days after duct ligation and then decreased in number. TUNEL-positive myoepithelial cells appeared at 2 days and were observed most frequently at 5 days. Apoptotic myoepithelial cells were also identified by TEM. These observations suggest that both apoptosis and proliferation of myoepithelial cells occur, especially in the early phase of atrophy, in the rat submandibular gland.

From three-dimensional space vision to prehensile hand movements: the lateral intraparietal area links the area V3A and the anterior intraparietal area in macaques

The posterior parietal cortex is included in the dorsal cortical visual pathway underlying the three-dimensional (3-D) visual recognition of space and objects. The neurons in the lateral intraparietal area (LIP) respond visually to the three-dimensional objects, whereas those in the anterior intraparietal area (AIP) respond to hand movements to grasp them. LIP receives visual inputs from V3A, whereas AIP projects to the premotor areas; however, it is not known whether the neurons in LIP project to AIP. We herein investigated the connectional substrates that underlie the transformation of three-dimensional vision to prehensile hand movements in the Japanese monkey (Macaca fuscata). After identifying the three-dimensional visually responsive region in the posterior part of LIP by the unit recordings, we injected a bidirectional tracer, wheat germ agglutinin conjugated to horseradish peroxidase, into one of the recording sites. We found that LIP receives neuronal projections from V3A and sends axons to AIP. To confirm our findings, we injected several orthograde tracers into V3A and retrograde tracers into AIP in the same hemispheres. We found that the V3A neurons projecting to LIP terminate in the vicinity of the LIP neurons projecting to AIP. The results suggest that the cortical connections of V3A-LIP-AIP in the lateral bank of the intraparietal sulcus play an important role in the visuomotor transformation for prehensile hand movements.

A light microscopic study of the attachment mechanism in different kinds of adhesive lines in rat molars

This study was designed to observe drifting molars of 70-day-old rats by light microscopy, and to elucidate whether there are similar attachment mechanisms at different kinds of adhesive lines in periodontal mineralized tissue of the rat molar region. Three kinds of adhesive lines--cement lines on resorbed alveolar bone, cement lines on resorbed roots, and cemento-dentinal junctions were examined. The two kinds of cement lines showed similar histological and histochemical features, they were proteoglycan-rich and fiber-poor. They appeared to form on the resorbed tissue before principal fiber reattachment. After covering by new bone or by reparative cementum, the cement lines retained the original features. The cemento-dentinal junction showed features very similar to those of the cement lines. Previous studies have suggested that the cemento-dentinal junctions bind the cementum and dentine by adhesion of proteoglycans. Structural similarities suggest that cement lines provide similar links between new bone and resorbed bone and between resorbed root and reparative cementum. In conclusion, this study suggests that there is one attachment mechanism for the different kinds of collagen based hard tissue in the rat molar region.

The nature and function of mononuclear cells on the resorbed surfaces of bone in the reversal phase during remodeling

In a reversal phase of bone remodeling many mononuclear cells appear on the resorbed surfaces of bone with characteristic reversal lines as revealed by transmission electron microscopy (TEM). However, these mononuclear cells have been variously hypothesized or reported. The present study examined the TEM features on the resorbed surfaces of three calcified connective tissues, and aimed to clarify the nature and function of the mononuclear cells in a reversal phase. Dentine slices cultured with isolated osteoclasts, human deciduous teeth, and rat mandibles were used in this study. Specimens were fixed, decalcified, and then embedded in Epon 812, and sectioned into 0.1-microm-thick ultrathin sections. The ultrathin sections were stained with uranyl acetate and lead citrate, and then examined by TEM. Many sharply pointed collagen fibrils with striation were observed exposed on the resorbed surfaces of cultured dentine slices, but there were neither cells nor reversal lines. The same features were observed on the root dentine surfaces of human deciduous teeth. Under many mononuclear cells in a reversal phase of remodeling, reversal lines were seen on the resorbed surfaces of rat mandibles, but there were no striated collagen fibrils exposed on the bone surfaces. The alternation of the TEM features on the resorbed surfaces before and after the participation of mononuclear cells in a reversal phase of remodeling suggests the nature and function of these cells: they participate in both degrading the demineralized and disrupted matrix left on the resorbed surfaces and forming reversal lines there.

Apoptosis and mitosis of parenchymal cells in the duct-ligated rat submandibular gland

Apoptosis and proliferation of parenchymal cells during atrophy of rat submandibular gland induced by double duct ligation were investigated using immunohistochemistry for proliferating cell nuclear antigen (PCNA), terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-digoxigenin nick end labelling (TUNEL) and transmission electron microscopy (TEM). At 2 and 3 days after ligation, increased PCNA positive cells and mitoses were seen in ducts; thereafter PCNA positive cells decreased in number. At 3 and 4 days, the acinar cell population rapidly decreased, with many remaining TUNEL positive acinar cells. During this period, TEM showed typical apoptotic acinar cells that were phagocytosed by adjacent acinar cells or intraepithelial macrophages. After 7 days, most acinar cells had disappeared, leaving prominent residual ducts; a few acinar cells remained, especially at the lobule periphery. Submandibular gland duct ligation thus induced marked depletion of acinar cell by apoptosis and a concurrent short-lived cycle of duct cell proliferation.

Light and electron microscopic study of the initial attachment of principal fibers to the alveolar bone surface in rat molars

This study was designed to observe the principal fibers and alveolar bone in various developmental stages in rat molars using light and transmission electron microscopy and to elucidate the mechanism of initial principal fiber attachment to the alveolar bone surface. Maxillary alveolar bone between the 2nd and 3rd molars of 20- and 25-day-old rats was used. A proteoglycan-rich, fiber-poor, and electron dense layer formed on the alveolar bone surface before the principal fiber organization. This layer was not seen before principal fibers had started to develop. Principal fibers first contacted and then became embedded in this layer. With further development, new bone deposited on this layer and around already attached principal fibers. These findings suggest that this electron dense, proteoglycan-rich layer may act as an adhesive factor to mediate the initial attachment of principal fibers to the alveolar bone surface.

Some osteocytes released from their lacunae are embedded again in the bone and not engulfed by osteoclasts during bone remodeling

It is generally accepted that osteocytes derive from osteoblasts that have secreted the bone around themselves. Osteocytes are cells embedded in the lacunae in the bone, and they are characteristically in contact with other cells by many slender cytoplasmic processes in canaliculi. During bone remodeling, many osteocytes in the bone are released from their lacunae by osteoclasts; however it remains unclear what happens to these released osteocytes. The cortical bone of the rat mandibular body was used in this study. Mandibles were fixed, decalcified, and then embedded in Epon 812. Specimens were sectioned in the frontal direction into serial 0.5 microm-thick semithin or 0.1 microm-thick ultrathin sections, and then examined by light or transmission electron microscopy. Cells that fitted in the osteocytic lacunae with canaliculi extending to the bone were identified as osteocytes in this study. Among many osteocytes released by osteoclasts in cutting cones, there were osteocytes half-released from their lacunae. These cells fitted in their lacunae with canaliculi extending to the bone and showed developed cell organelles in the cytoplasm. In closing cones, many osteocytes were situated in the bone away from cement lines; however, there were half-embedded osteocytes in the bone formed on cement lines. These cells fitted in their lacunae with canaliculi extending to the bone formed below cement lines and showed developed cell organelles in the cytoplasm. These results show that half-embedded osteocytes in closing cones derive from half-released osteocytes in cutting cones. Osteocytes encircled by osteoclasts were sometimes observed on one section, but serial sections showed that these osteocytes fitted in their remaining lacunae in the bone on other sections. This shows that not all osteocytes released from their lacunae are engulfed by osteoclasts. Consequently, the present results suggests that some osteocytes released from their lacunae are embedded again in the bone and not engulfed by osteoclasts during bone remodeling.

Two novel first exons in the prolactin receptor gene are transcribed in a tissue-specific and sexual maturation-dependent manner to encode multiple 5'-truncated transcripts in the testis of the chicken

Cloning and sequencing of the chicken prolactin receptor (PRLR) gene segment from the transmembrane domain to the box 2 motif revealed the presence of the two testis-specific first exons, TSE-1 and TSE-2, encoding the unique 5'-end sequences of the reported and newly identified multiple 5'-truncated PRLR transcripts containing only the cytoplasmic domain in the testis. TSE-1 was located downstream of the exon encoding the transmembrane domain and TSE-2 presented downstream of the exon encoding the box 1 motif. These findings indicate that the box 1-containing 5'-truncated transcripts are generated by the utilization of TSE-1 as the first exon with distinct splicing donor sites to the box 1-containing exon, and that the utilization of TSE-2 as the first exon and its splicing to the box 2-containing exon results in the generation of the box 1-lacking transcript. Three transcription initiation sites for the box 1-containing 5'-truncated transcripts and two transcription initiation sites for the box 1-lacking transcript were detected by the RNase protection assays. Reverse transcription-polymerase chain reaction analysis showed that the expression levels of all these 5'-truncated PRLR transcripts are simultaneously increased during sexual maturation, accompanying the decrease of the amount of the canonical full-length transcript for PRLR.

Ultrastructural study of the root dentine surface resuming resorption on human deciduous teeth

Resorption of deciduous teeth is not continuous, but alternates with periods of repair or rest. Dentine surfaces in periods of rest or repair resume resorption by odontoclasts during physiological root resorption of the deciduous teeth. However, no observations of such dentine surfaces have been shown. The characteristic feature of the dentine surfaces resuming resorption remains unknown. Tartrate-resistant acid phosphatase activity (TRAP) was detected on human deciduous teeth. The root resorbing surfaces on these teeth were photographed with a whole-mount light microscope, and the photographed areas were serially sectioned into 0.5 micron semithin sections. Preodontoclasts and odontoclasts were three-dimensionally reconstructed. On root resorbing surfaces, areas with small scattered TRAP-positive cells were observed among areas with many TRAP-positive resorbing odontoclasts and TRAP-negative areas. The sections showed that areas with small scattered TRAP-positive cells have features similar to those of TRAP-negative areas, but there were three kinds of characteristic TRAP-positive cells: preodontoclasts, odontoclasts forming small lacunae, and preodontoclasts, and odontoclasts with cytoplasmic processes extending to the dentine surface, which is covered with cells. These results suggest that the areas with small scattered TRAP-positive cells could be at the stage of resuming resorption, and show that the presence of preodontoclasts and odontoclasts with cytoplasmic processes extending to the covered dentine surface is a characteristic feature of the dentine surface at this stage.

The structure of the cemento-dentinal junction in rat molars

The cemento-dentinal junction was observed in the acellular and cellular cementum of rat molars by light and scanning electron microscopy. Scanning electron microscopy, combined with NaOH maceration, was used to observe the fibrous architecture directly in this region. Light microscopy revealed that the cemento-dentinal junction contains fewer collagen fibrils and more proteoglycans than the cementum and dentin. Scanning electron microscopy also showed that fibril intermingling is found only in some regions of the fibril-poor junction in macerated specimens. Prolonged maceration breaks down the cemento-dentinal junction in spite of the fibril intermingling. Only macerated specimens showed detachment here. It was established that NaOH maceration removes interfibrillar substances effectively, and does not damage the fibril structure or architecture. This suggests that the adhesion of proteoglycans is more important than fibril intermingling for preserving the cemento-dentinal attachment in the rat molar.

Brain-derived neurotrophic factor expands ocular dominance columns in visual cortex in monocularly deprived and nondeprived kittens but does not in adult cats

Segregation and stabilization of thalamocortical afferents to eye-specific patches, so-called "ocular dominance (OD) columns," in visual cortex are hypothesized to be based on activity-dependent competition for trophic factors such as brain-derived neurotrophic factor (BDNF) between afferents representing the two eyes during the critical period of postnatal development. To test this hypothesis we observed effects of an intracortical infusion of BDNF on OD columns in monocularly deprived kittens and also compared effects between normal kittens and adult cats. BDNF had a hypertrophic action on afferents irrespective of visual inputs so that it desegregated OD columns in the visual cortex of deprived and normal kittens, but this action was not seen in the adults, substantiating its hypothesized trophic role in plasticity of OD columns in the developing visual cortex.

Changing myoepithelial cell distribution during regeneration of rat parotid glands

The distribution of the myoepithelial cells during regeneration of the rat parotid gland after atrophy induced by one week of parotid duct ligation was investigated by immunohistochemistry for actin and transmission electron microscopy (TEM). Immunohistochemically, residual ducts were surrounded by actin-positive cells when clips were removed from the duct. Three days later, most of the newly formed acini originating from the residual ducts were also embraced by actin-positive cells. After 10 days, actin-positivity tended to be seen as dots around acini that decreased in number day by day. On day 21 actin-positive cells mainly surrounded intercalated ducts with only a few positive reactions identified at the acinar periphery. Electron microscopically, residual ducts and newly formed acini were peripherally embraced by myoepithelial cells before day 5. After day 7, shift of myoepithelial cells from the periphery of acini to the duct-acinar junctional region was identified. Then few myoepithelial cells were identified at the periphery of acini. These observations indicate that myoepithelial cells migrate from the acinar periphery to the duct-acinar junctional region during rat parotid regeneration, and that such behaviour is closely related to that seen during rat parotid development.

The structure and function of the cemento-dentinal junction in human teeth

The structure and function of the cemento-dentinal junction were studied in human molars by light and electron microscopy. The cemento-dentinal junction was an approximately 1-3-micron-thick layer full of proteoglycans with mucopolysaccharides but containing fewer collagen fibrils than the root dentin and cementum. In places, cemental fibrils crossed the cemento-dentinal junction. These fibrils appeared to intermingle with dentinal fibrils. By enzymatic treatment of decalcified specimen with hyaluronidase and trypsin, the cemento-dentinal junction decreased or lost staining affinity to toluidine blue. Prolonged treatment caused the separation of cementum from the root dentin during routine histological processes. These data suggest that the adhesion of proteoglycans is more important than the intermingling of dentinal and cemental fibrils for the cemento-dentinal attachment.

cDNA cloning and developmental alterations in gene expression of the two Pit-1/GHF-1 transcription factors in the chicken pituitary

Pit-1/GHF-1 (Pit-1) transcription factors promote the gene expressions for growth hormone (GH), prolactin (PRL), and the beta chain of thyroid-stimulating hormone in vertebrate pituitary glands. The present study analyzed the nature of chicken Pit-1s (cPit-1s) and their developmental expressions in the pituitary. Chicken pituitary expressed two cPit-1 mRNAs encoding cPit-1alpha and cPit-1gamma composed of 335 and 327 amino acid residues, respectively. They possessed different N-terminal regions and the common C-terminal regions containing a POU-specific domain and a POU homeodomain. Northern blot analysis revealed the pituitary-specific expressions of these Pit-1 mRNAs, and the Pit-1alpha mRNA expressions were two to three times higher than those for Pit-1gamma in both cephalic and caudal lobes of the pituitary. The cPit-1alpha and gamma mRNA expressions simultaneously increased after hatching until 4 weeks and then slightly decreased at 5 weeks. Similar gene expression profiles were observed for GH and PRL during the posthatch developmental period.

The structure and function of periodontal ligament cells in acellular cementum in rat molars

To elucidate the structure and function of periodontal ligament cells at the periodontal ligament-cementum interface in advanced acellular cementogenesis, the cervical regions of molars in rats aged 6 weeks were observed by light and electron microscopy. The light and transmission electron microscopy showed the periodontal ligament cells to be elongated between dense, well-developed principal fibers. The transmission and scanning electron microscopy showed that these cells extended wing-like projections from the lateral surface, forming cylindrical compartments surrounding the principal fibers. In addition, finger-like projections extended toward the cementum from the cementum-facing ends. The main results suggest the following: at the periodontal ligament-cementum interface, the periodontal ligament cells maintain the architecture of the principal fibers by means of extracellular compartments. The arrangement of finger-like projections results in the formation of acellular cementum containing only Sharpey's fibers as a fibrous component.

Increase in odontoclast nuclei number by cell fusion: a three-dimensional reconstruction of cell fusion of human odontoclasts

Osteoclasts and odontoclasts are known to increase their nuclear number by fusion of mononuclear precursors. However, the pattern of fusion remains morphologically unclear. One lower right deciduous canine of an 8-year-old male was investigated. Tartrate-resistant acid phosphatase activity (TRAP) positive cells on the resorbing surface of the tooth were serially sectioned into 0.5 microm-thick semithin sections. The sections were photographed, and cells possessing a light microscopic brush border facing a resorptive lacuna were identified as odontoclasts. Fourteen odontoclasts appearing as a continuous figure of cellular membrane between cells on one section were three-dimensionally reconstructed using NIKON COSMOZONE 2SA. A criterion for fusion was established in this study, requiring that there must be two or more nucleated cells which contacted each other at one site only in the three-dimensional reconstruction. Among 14 reconstructed cells, 10 odontoclasts satisfied the criterion for fusion. The observations of the three-dimensional structures of these odontoclasts showed that mononuclear and multinucleated odontoclasts participated in fusion. Cell fusion occurred between resorbing odontoclasts and cells not forming lacunae, and between resorbing odontoclasts. A case of odontoclastic fusion among three cells was also observed. The results establish that fusion resulting in multinucleation occurred among various odontoclasts with different numbers of nuclei including mononuclear odontoclasts.

Constitutive expression of a heterologous Eubacterium ruminantium xylanase gene (xynA) in Butyrivibrio fibrisolvens

An Eubacterium ruminantium xylanase gene (xynA) was inserted into pYK4, a shuttle vector replicable in both Escherichia coli and Butyrivibrio fibrisolvens, and the resultant chimeric plasmid (pYK4XT) was electroporated into B. fibrisolvens OB156C in an attempt to obtain a more xylanolytic B. fibrisolvens. Electrotransformants were screened by the development of erythromycin resistance, followed by an activity staining and Southern hybridization. The presence of mRNA from xynA in the transformant, B. fibrisolvens NO4, was confirmed by Northern hybridization. Xylanase activity of the transformant NO4 was apparently enhanced regardless of carbon sources in the medium. When grown on glucose or cellobiose. NO4 had approximately 5-6 times higher intracellular activity than the parent OB156C on a culture volume basis as well as protein basis. The transformant showed extracellular xylanase activity much higher (between 7- and 10(4)-fold) than the parent. Transformant NO4 recorded the highest activity when grown on xylan. Most (> 90%) of the activity was extracellular. The extracellular activity was 2-fold greater in NO4. These findings indicate that the introduced xynA was expressed constitutively and the xylanase protein was exported into the culture supernatant. Growth of NO4 on glucose was similar to that of OB156C, which suggests little extra load for plasmid maintenance and foreign xylanase production in the transformant. The plasmid pYK4XT was maintained stably in the transformant for more than 100 generations.

Thyroid hormones are involved in insulin-like growth factor-I (IGF-I) production by stimulating hepatic growth hormone receptor (GHR) gene expression in the chicken

Effect of thyroid status on IGF-I production in growing chickens was studied. Serum concentrations of GH were not affected by propylthiouracil (PTU) or thyroxine (T4) treatments, whereas serum IGF-I levels were significantly decreased in PTU-treated chickens. The lowered serum IGF-I levels in the PTU-treated group were completely restored to the control levels by T4 injections. In the liver, the messenger RNA (mRNA) expressions both for GH receptor (GHR) and IGF-I were significantly repressed by PTU treatment, and were restored again by T4 replacement. In addition, the results of analysis on radiolabelled GH binding to the liver membrane were consistent with the levels of hepatic GHR mRNA expression. Serum concentrations of IGF-I were positively correlated with hepatic IGF-I mRNA and GHR mRNA expressions. The correlation coefficient between serum T3 levels and hepatic IGF-I mRNA expressions was also significant. These results indicate that thyroid hormones regulate IGF-I production in the chicken by affecting hepatic GHR expression.

The regulation of fiber arrangement in advanced cellular cementogenesis of human teeth

This study observed cellular cementum in fully formed human premolars by light and electron microscopy to elucidate how cementoblasts regulate the fiber arrangement in cementum. Cementoblasts had wing-like processes encircling the principal fibers, where Sharpey's fibers were dense. On the cementum-facing side, wing-like processes were segmented into finger-like processes in parallel with the cementum surface. Observations suggested that with the segmentation intrinsic fibers appeared around principal fibers in close association with finger-like processes. Where Sharpey's fibers were few or absent, where intrinsic fibers were the main fibrous element of the cementum, cementoblasts had only few or no wing-like processes, but had finger-like processes not associated with the wing-like processes on the cementum-facing side. On the basis of the origin of the finger-like processes the main results suggest that there are two kinds of cementoblasts: one has finger-like processes associated with wing-like processes and secretes intrinsic fibers from the finger-like processes to incorporate the principal fibers for tooth support. The second type has finger-like processes not associated with wing-like processes, this type secretes intrinsic fibers from the finger-like processes to adjust the cementum thickness.

Proliferative effects of several hematopoietic growth factors on acute myelogenous leukemia cells and correlation with treatment outcome

The response of human acute myelogenous leukemia (AML) cells to four different hematopoietic growth factors (granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-1 beta (IL-1beta), interleukin-3 (IL-3), and stem cell factor (SCF)) and the relationship of the proliferative response of the AML cells to treatment outcome were studied. Proliferative responses were analyzed in 79 patients with de novo AML and 19 patients with AML arising from myelodysplastic syndrome (MDS). In de novo AML, a positive proliferative response (stimulation index >2) was seen in 65 to 75% of cases. AML cells arising from MDS had a much higher incidence of proliferative response to each growth factor (79 to 90%) and a much higher level of 3H-TdR incorporation. The relationship to treatment outcome was evaluated in 79 patients with de novo AML. The patients whose leukemic cells had a positive proliferative response to any growth factor, especially IL-3 and SCF, had a poorer outcome, ie a lower complete remission (CR) rate, shorter CR duration, and shorter survival. The outcome was particularly poor in patients whose leukemic cells had proliferative responses to all four or any of the growth factors, compared to patients whose leukemic cells had no response. This increased response may be a marker of poor prognosis in patients with AML.

Mononuclear odontoclast participation in tooth resorption: the distribution of nuclei in human odontoclasts

Osteoclasts and odontoclasts have been considered multinucleated giant cells which resorb hard tissue by ruffled borders. Recently, the authors reported the presence of a mononuclear osteoclast and odontoclast with a ruffled border. However, the relative frequency of such cells and the distribution of the number of nuclei including mononuclear cells in them have not been elucidated. Six human deciduous teeth were used in this study. After fixation and decalcification, tartrate-resistant acid phosphatase (TRAP) activity was detected with the azo dye method, and then TRAP-positive cells were observed on resorbing areas of teeth by light microscopy. The cells for investigation were serially sectioned by semithin sections to observe the presence of resorptive lacuna and the number of nuclei. The TRAP activity was detected in both multinucleated and mononuclear odontoclasts from serial semithin sections, and 242 TRAP-positive cells which formed lacunae on dentin were investigated to determine the frequency distribution of the number of nuclei. The mean number of nuclei per cell was 5.3, and median was 4. Only 2.9% of odontoclasts were mononucleus and 93.8% had 10 or fewer nuclei. The majority of odontoclasts forming lacunae on the dentin were cells with 10 or fewer nuclei, and mononuclear odontoclasts participated in human deciduous tooth resorption together with multinucleated ones.