Sporadic acute hepatitis E occurred constantly during the last decade in northeast Japan

BACKGROUND

Recent studies have shown that indigenous hepatitis E virus (HEV) strains cause hepatitis E in industrialized countries. We aimed to clarify the characteristics of HEV infection in sporadic hepatitis patients during the last decade in Miyagi, northeast Japan.

METHODS

We analyzed 94 serum samples obtained from acute or fulminant hepatitis patients of non-A, non-B, and non-C etiology between 1999 and 2008. Antibody to HEV (anti-HEV) was assayed, and patients who were positive for IgM- and/or IgA-class anti-HEV were diagnosed with hepatitis E. HEV RNA was tested in these patients, and phylogenetic analysis was performed. The occurrence of hepatitis E was compared with that of hepatitis A.

RESULTS

Eight acute hepatitis patients (8.5%) were diagnosed with hepatitis E, and HEV RNA was detectable in seven patients. Five isolates of HEV were segregated into genotype 3 and the remaining two isolates into genotype 4. The year of the occurrence of hepatitis E was distributed almost equally from 1999 to 2008, whereas the cases of acute hepatitis A (n = 16) have decreased markedly in the last several years. In 2004-2008, the occurrence of hepatitis E was greater than that of hepatitis A (five cases vs. one case). As for seasonality, hepatitis E occurred more frequently from September to December than hepatitis A (five cases vs. four cases), although less frequently from January to April (one case vs. seven cases).

CONCLUSION

The occurrence of hepatitis E has not decreased during the last decade in northeast Japan, in contrast to hepatitis A.

Transient elastography for measurement of liver stiffness measurement can detect early significant hepatic fibrosis in Japanese patients with viral and nonviral liver diseases

BACKGROUND

Many studies have reported the efficiency of transient elastography, a noninvasive, reproducible, and reliable method for predicting liver fibrosis, in patients with chronic hepatitis C (CHC) and B (CHB), but there are few reports about nonviral chronic liver disease (CLD) such as primary biliary cirrhosis (PBC), nonalcoholic steatohepatitis (NAFLD), and autoimmune hepatitis (AIH). We therefore compared the efficiency of transient elastography between CHC and nonviral CLD.

METHODS

We assessed the accuracy of liver stiffness measurement (LSM) using Fibroscan, and compared these values with those of hyaluronic acid, type 4 collagen, platelet count, prothrombin index, and AST/platelet ratio index (APRI) as indices for the diagnosis of liver fibrosis in 114 patients with a variety of chronic liver diseases: CHC (n = 51), CHB (n = 11), NAFLD (n = 17), PBC (n = 20), and AIH (n = 15). The histology was assessed according to the METAVIR score by two pathologists.

RESULTS

The number of fibrosis stage (F0/1/2/3/4) with CHC was 9/15/12/6/10, and that with nonviral CLD was 10/21/11/4/6, respectively. The ability, assessed by area under receiver operating characteristic (AUROC) curve, to predict liver fibrosis F >or= 2 for LSM, HA, type 4 collagen, platelet count, prothrombin index, and APRI, was 0.92, 0.81, 0.87, 0.85, 0.85, and 0.92 in CHC patients, respectively; and 0.88, 0.72, 0.81, 0.67, 0.81, and 0.77 in nonviral CLD patients, respectively.

CONCLUSIONS

In patients with nonviral CLD, LSM was most helpful in predicting significant fibrosis (F >or= 2). Transient elastography is a reliable method for predicting significant liver fibrosis, not only in CHC patients but also in nonviral CLD patients.

A case of HIV co-infected with hepatitis B virus precore/core deletion mutant treated by entecavir

We report a case of a HIV and hepatitis B virus (HBV)-co-infected patient to whom entecavir (ETV) was administered initially before the notification regarding the potential mutagenesis effect on HIV against the nucleoside analog. Since initial evaluations indicated the advanced stage of chronic hepatitis B and preserved numbers of peripheral CD4+ lymphocytes without the manifestation of immunodeficiency, priority was given to the management of HBV. We started HBV therapy with ETV at a dose of 0.5 mg daily without using any HIV drugs. The viral loads of both HBV and HIV-1 decreased gradually during the 5 months following the initial administration of ETV. HBV was well controlled by the gradual replacement of ETV with highly-active antiretroviral therapy against HIV with a regimen including atazanavir, emtricitabine, and tenofovir. HBV was genotyped as A2 with the quasispecies pool consisting of the -1G precore/core deletion mutant strain.

A case of severe recurrent hepatitis with common variable immunodeficiency

Severe hepatitis with an indistinct etiology manifested in a 16-year-old boy who had no particular history. The histological features of the liver and clinical course of the patient were similar to those of patients with autoimmune hepatitis characterized by interface hepatitis and severe lobular inflammation of the liver and recurrent exacerbations of hepatitis. We administered intravenous glycyrrhizin preparation daily or three times a week combined with the oral administration of ursodeoxycholic acid daily throughout the term after the initial onset of disease for the control of disease activity. The normalization of the concentration of alanine aminotransferase in serum was achieved in response to the therapy during the course. The serum concentration of immunoglobulins of the patient gradually decreased from the onset of the disease to an unacceptable level without globulin preparation during the following period of 17 months. Immunological tests revealed impairment of immunoglobulin production bythe B cell population of the patient, which led to the diagnosis of the patient as common variable immunodeficiency (CVID). The patient, with improved liver histology after 27 months from the onset of disease, benefited from the current combination therapy without severe infection through the avoidance of overimmunosuppression. CVID is defined as a heterogeneous syndrome characterized by various degrees of hypogammaglobulinemia without any specific predisposing causes, frequently associated with autoimmunity. Diagnostic criteria and therapeutic options of persistent hepatitis with CVID are to be established, as discussed in the current report.

Fulminant hepatic failure in a case of autoimmune hepatitis in hepatitis C during peg-interferon-alpha 2b plus ribavirin treatment

A 27-year-old Caucasian female with hepatitis C virus (HCV) infection treated with interferon (IFN) who developed severe autoimmune hepatitis (AIH) is described. The infecting viral strain was of genotype Ib and the pre-treatment HCV viral load was at a high level. The patient was treated with pegylated IFN-alpha 2b and ribavirin, and her HCV-RNA became negative at wk 12, but after that she developed fulminant hepatic failure. The patient recovered after steroid pulse therapy consisting of methylprednisolone 1000 mg/d for three days which was administered twice. A needle liver biopsy revealed the typical pathological findings of AIH.

Interleukin-6 and Tumor Necrosis Factor-α in Patients with Obstructive Sleep Apnea-Hypopnea Syndrome

BACKGROUND

In previous studies, significantly elevated levels of vascular endothelial growth factor (VEGF) have been reported in patients with severe obstructive sleep apnea-hypopnea syndrome (OSAHS). On the other hand, plasma tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) have been significantly higher in mild sleep apneics than in normal controls. However, this study included a small number of patients and milder cases of OSAHS.

OBJECTIVES AND METHODS

To assess the involvement of IL-6 and TNF-alpha in VEGF increases in patients with severe OSAHS, serum levels of IL-6 and TNF-alpha were determined in patients with severe OSAHS (n=110) and compared to those of controls (n=45) using an enzyme-linked immunosorbent assay.

RESULTS

No significant increase in IL-6 or TNF-alpha was detected in the present study cohort. However, the body mass index was significantly correlated with the severity of the apnea-hypopnea index.

CONCLUSIONS

These data suggest that the elevation in VEGF is not directly related to IL-6 or TNF-alpha levels. However, the question of whether VEGF is the cause or the result of OSAHS remains to be determined. Further studies are needed to clarify the role of IL-6 and TNF-alpha in the pathogenesis of OSAHS, in which obesity should be entered as an independent factor.

Successful Treatment of Severe Hypertension with the Combination of Angiotensin Converting Enzyme Inhibitor and Angiotensin II Receptor Blocker

Three patients who suffered from congestive heart failure caused by severe hypertension were treated with a combination therapy consisting of angiotensin converting enzyme inhibitor (ACEI) and angiotensin II receptor blocker (ARB). Before initiation of treatment, all three patients showed elevations of serum creatinine concentration (sCr), plasma renin activity (PRA), and plasma aldosterone concentration (PAC), which indicated insufficient blood supply to the kidney during exacerbation of hypertension. All three cases successfully recovered from hypertensive heart failure with the combination therapy. sCr gradually decreased during continuation of the therapy, although one patient showed an increase in sCr at an early stage of the combination therapy. Blockade of the renin-angiotensin-aldosterone system (RAAS) by the combination of ACEI and ARB was well tolerated in patients with severe hypertension with renal damage and showed a beneficial effect in protecting against further renal damage. This result suggests that combination therapy with ACEI and ARB should be considered as a candidate treatment in cases of severe hypertension.

Detection of minimal residual disease in a patient having acute myelogenous leukemia with t(16;21)(p11;q22) treated by allogeneic bone marrow transplantation

A 29-year-old woman having acute myelogeneous leukemia-M1 subtype with the chromosomal abnormality t(16;21)(p11;q22) is presented. Complete blood count at onset showed a hemoglobin level of 7.2 g/dl, a platelet count of 48 x 10(9)/l, and a white blood cell count of 161.2 x 10(9)/l with 99% blasts and 1% lymphocytes. Bone marrow aspiration revealed massive proliferation of blasts that were positive for CD13, CD33, CD34, CD56 and myeloperoxidase, and negative for other T-cell, B-cell and monocytic markers. After achieving complete remission following conventional chemotherapy, she received an HLA-matched bone marrow transplantation (BMT) from her sibling after conditioning with busulfan, etoposide and cyclophosphamide. However, 9 months later, the leukemia relapsed as a painful extramedullary mass in her left femur. In spite of intensive re-induction chemotherapy, she died of progressive disease and sepsis. Although we could not detect the TLS/FUS-ERG fusion transcripts by reverse transcriptase-polymerase chain reaction in pre-BMT remission phase, they were clearly detectable in bone marrow cells obtained 6 months after transplantation with no translocation detected by conventional cytogenetics. We consider that even high-dose chemotherapy with BMT may not be effective in the eradication of this type of leukemia, and that the detection of minimal residual disease possibly contributes to the better planning of the therapeutic strategy.

A comparative study of an olfactory epithelial area lacking olfactory neurons and a nearby presence of TGF-alpha-like immunoreactive olfactory neurons

Our previous study has shown that ddY mice have special patches of nasal epithelium in the posterior roof of the nasal cavity that exclusively consists of olfactory supporting cells and horizontal basal cells. Here, we extend this finding to Balb/c and DBA/2 mice, Wistar and Sprague-Dawley rats, hamsters, and guinea pigs. In the mice, rats, and hamsters studied, the patches lacked olfactory cells and their precursor, globose basal cells. In rats and hamsters, the supporting cells were arranged in a single layer, in mice as three or four layers. Horizontal basal cells were located in a single layer in these species. In the guinea pigs, the specialized roof structure was less clear and could be seen at the level of ultrastructure as an olfactory neuron-lacking area. Distinct populations of transforming growth factor (TGF)-alpha-like immunoreactive olfactory cells occupied an area close to the epithelial patches. In this region, the TGF-alpha-like immunoreactive neurons were negative for the usual olfactory markers, either OMP or protein gene product (PGP) 9.5 or beta-tubulin. These cells are suggested to project to the so-called 'necklace glomeruli' and use a different cGMP-driven, transduction pathway. Three-dimensional analysis of double-labeled (TGF-alpha, PGP9.5) serial sections revealed a unique relation among the epithelial patches, TGF-alpha-like immunoreactive neurons and olfactory epithelium.

Induction of apoptosis by colchicine in taste bud and epithelial cells of the mouse circumvallate papillae

Apoptotic cells in the taste buds and epithelia of mouse circumvallate papillae after colchicine treatment were examined by the methods of in situ DNA nick-end labeling, immunocytochemistry, and electron microscopy. After colchicine treatment, numerous positive cells appeared in the taste buds by DNA nick-end labeling, and some epithelial cells in the basal and suprabasal layers in and around the circumvallate papillae also revealed positive staining. Condensed and fragmented nuclei with a high density were occasionally found in the taste bud cells and in the basal and suprabasal layer epithelial cells by electron-microscopic observation. An immunocytochemical reaction for tubulin revealed weak staining in taste bud cells, because of the depolymerization of microtubules, and a decrease of the microtubules in the taste bud cells was observed by electron microscopy. These results indicate that colchicine treatment of mice induces the apoptosis of taste bud and epithelial cells in the circumvallate papillae and dorsal epithelial cells around the circumvallate papillae.

Olfactory epithelium consisting of supporting cells and horizontal basal cells in the posterior nasal cavity of mice

The olfactory epithelium of mice generally consists of olfactory cells, progenitors of olfactory cells (globose basal cells), supporting cells, and horizontal basal cells. However, in the dorsal fossa (the roof) of the posterior nasal cavity of mice, we found seven epithelial patches consisting of only non-neuronal cell types, i.e., supporting cells and horizontal basal cells, among the normal olfactory epithelium. The supporting cells occupied three or four layers in the apical to middle regions; in the basal region, horizontal basal cells were localized in a single row adjacent to the basement membrane. Bowman's gland ducts were also present in the epithelium. Neuronal cells (olfactory cells and globose basal cells) were totally absent. The ultrastructure of the supporting cells, horizontal basal cells, and Bowman's glands was essentially similar to that in the normal olfactory epithelium. In the early postnatal period (P1-P7), cell types in the epithelium were the same as those in the normal olfactory epithelium. From P10 to P21, olfactory cells and globose basal cells had disappeared from the olfactory epithelium. At this period, the number of TUNEL-positive cells was significantly higher than that in the surrounding olfactory epithelium; ultrastructurally, many apoptotic figures were observed. This suggests that the epithelium consisting of supporting cells and horizontal basal cells is generated by the apoptotic death of olfactory cells and globose basal cells during postnatal development.

[T-cell prolymphocytic leukemia with CD4+8+25+ phenotype in a patient presenting with venous thrombosis in the lower leg]

A 58-year-old man was referred to our hospital because of painful swelling in the left lower leg and leukocytosis in January 1999. Moderate hepatosplenomegaly but no lymph node swelling was observed. Marked leukocytosis (leukocytes 44.9 x 10(4)/microliter with 95% morphologically prolymphocytes) and thrombocytopenia were detected. The surface phenotype of the leukemia cells was CD1-2+3+5+7+4+8+25+. Magnetic resonance imaging revealed dilated veins in the left lower leg. An abnormal 47XY, +22 karyotype was detected in 1/20 cells. Tests for HTLV-I antibody were negative. A diagnosis of T-cell prolymphocytic leukemia (T-PLL) was made on the basis of data including cytochemical and electron microscopic findings. Although 2 courses of chemotherapy comprising vincristine, cyclophosphamide, and prednisolone improved the venous thrombosis in the leg, the leukemia cells were refractory to chemotherapy. To prevent the recurrence of venous thrombosis due to leukostasis, the patient underwent repeated leukapheresis. The leukocyte count was maintained at around 20.0 x 10(4)/microliter after total 7 courses of leukapheresis, one course of which comprised 7l of extracorporeal circulation. In addition to the rare presentation of venous thrombosis, the CD4+8+25+ phenotype observed in this case is rare in patients with T-PLL.

Derivative (1;7)(q10;p10) in a patient with de novo acute erythroblastic leukemia (AML-M6)

A rare association of der(1;7)(q10;p10) with de novo acute erythroblastic leukemia (AML-M6) in a 63-year-old male is reported. While this unbalanced 1;7 translocation, der(1;7), has been reported often in therapy-related myelodysplastic syndrome (t-MDS) or therapy-related acute myeloid leukemia (t-AML), its associations with de novo AML-FAB-M6 have rarely been reported. Although der(1;7) has been reported as a cytogenetic factor for poor prognosis in t-MDS/AML, our patient showed a good response to chemotherapy and obtained complete remission, although longer observation is required to evaluate the prognosis.

Immunofluorescence detection of cadherins in mouse tooth germs during root development

The distribution of two cell-adhesion molecules, E- and P-cadherin, was studied in relation to morphological changes in Hertwig's epithelial root sheath Before root dentinogenesis had started, the root sheath expressed both cadherins. As dentinogenesis proceeded, the sheath fragmented and lost P-cadherin rapidly and E-cadherin slowly, whereas the intact sheath at the apical end continued to express both. These results suggest that the two cadherins play a part in root as well as in crown development, and indicate that the decrease in the amount of these molecules and the fragmentation of the epithelial root sheath are interrelated.

Expression of the neural cell adhesion molecule in mouse taste buds after denervation

Expression of the neural cell adhesion molecule (NCAM) was studied by use of an immunocytochemical technique in the taste buds of mouse circumvallate papillae after bilateral transection of the glossopharyngeal nerves. In untreated mice, innervated type-III cells reacted with anti-NCAM antibody. After denervation the taste buds gradually decreased in number and size, and were practically absent within 11 days. In parallel, NCAM-reactive cells decreased at 3 and 8 days after surgery and at 11 days they were no longer found. Three days after denervation, synaptic contacts between type-III cells and nerve fibres were not found because of the disappearance of nerve fibres. However, remaining type-III cells, characterized with dense-cored vesicles, still maintained NCAM expression on their plasma membrane until day 8.

Colchicine-induced cell death and proliferation in the olfactory epithelium and vomeronasal organ of the mouse

The cytotoxic agent colchicine induced apoptotic cell death and subsequent regeneration in the mouse olfactory epithelium and vomeronasal organ. The TUNEL method revealed the presence of many apoptotic bodies in the middle to basal region of the septal olfactory epithelium and vomeronasal organ near the boundary of the respiratory epithelium at 1 day after a single i.p. injection of colchicine (4 mg/kg b.w.). In some regions of the third and the fourth nasal turbinates, massive apoptosis was observed in the olfactory epithelium. Electron micrographs of the septum showed that immature olfactory cells and globose basal cells were killed by the colchicine and had been phagocytized by the supporting cells and macrophages. In the vomeronasal organ, immature sensory cells and precursors died in response to the colchicine. In response to cell death, active proliferation of precursor cells (globose basal cells) and subsequent regeneration of olfactory cells occurred in the olfactory epithelium and vomeronasal organ. Incorporation of the mitotic tracer BrdU by precursor cells reached its peak at 4 days after colchicine treatment in the vomeronasal organ, and at 6 to 7 days in the olfactory epithelium; however, in some regions in the third and the fourth nasal turbinates, where many olfactory cells and globose basal cells had died by colchicine effect, the regeneration did not occur even in 1 month, forming the epithelium of only supporting cells and horizontal basal cells. In the next month, these regions became normal olfactory epithelium. This suggests that the globose basal cells in the surrounding normal olfactory epithelium might invade these regions to give rise to the olfactory cells.

Bulbectomy of neonatal mice induces migration of basal cells from the olfactory epithelium

Bulbectomy of neonatal mice induced cell migration from the olfactory epithelium in the nasal septum. We examined cell types of migrating clusters by immunohistochemistry using anti-keratin and anti-BrdU antibodies, and by electron microscopy. At 1-2 days after unilateral bulbectomy of P1 mice, cells migrated from the olfactory epithelium to the lamina propria of the septal olfactory mucosa. Horizontal basal cells that reacted specifically with anti-keratin antibody, and globose basal cells characterized by a round shape and poor content of organellae in their cytoplasm, were contained in the cluster. At 1 week, migrated clusters that contained keratin-positive horizontal basal cells were observed in both the lamina propria and olfactory bulb on the unoperated side. At 1 month, not only basal cells but also olfactory cells and presumed supporting cells were involved in the clusters in the lamina propria and olfactory bulb, suggesting that migrated cells do not transform to other phenotypes.

Expression of E- and P-cadherin during tooth morphogenesis and cytodifferentiation of ameloblasts

Cell-cell adhesion is fundamental in morphogenesis and is known to be mediated by several groups of cell adhesion molecules. Cadherins are a group of such molecules involved in the Ca2+-dependent cell-cell adhesion mechanism and are found in most kinds of tissue. In this study using indirect immunofluorescence microscopy, we analyzed the distribution of two kinds of cadherins, E- and P-cadherin, in developing tooth germs. In the molar tooth germs at the early bud stage, marginal cells of the epithelial tooth bud expressed both E- and P-cadherin, whereas central cells expressed only E-cadherin. At the cap stage, in addition to the cells of the inner and outer enamel epithelium, which outline the enamal organ, cells of the enamel knot, which is thought to control tooth morphogenesis, strongly expressed P-cadherin. The expression of P-cadherin was prominent in the inner enamel epithelium during the early to mid bell stage, and was also evident in the non-dividing cell masses at future cusp tips, which are the so-called secondary enamel knots. In the tooth germ at the late bell stage when the cells of the inner enamel epithelium began to polarize to differentiate into ameloblasts, the polarizing ameloblasts lost P-cadherin and strongly expressed E-cadherin. However, E-cadherin was also lost from polarized ameloblasts at later stages. The stratum intermedium and the stellate reticulum were E-cadherin positive from the bell stage onward even at the stages when the ameloblasts became E-cadherin negative again. These results suggest that the differential expression of E- and P-cadherin during morphogenetic stages plays a role in the regulation of tooth morphogenesis, whereas alteration of E-cadherin expression during later stages of tooth development is related to differentiation and function of the ameloblasts and other cells supporting amelogenesis.

Effect of denervation on lymphocytes and dendritic cells in the rat circumvallate and foliate papillae

The distribution of dendritic (Langerhans) cells and lymphocytes in rat circumvallate and foliate papillae was examined by immunohistochemistry and electron microscopy. Light microscopic immunohistochemistry using anti-OX62 antibody, which recognizes both gammadelta T lymphocytes and dendritic cells, showed that many OX62-immunoreactive cells had invaded into the trench wall epithelium from the connective tissue at 6 days after sectioning of the glossopharyngeal nerves. The presence of OX62-immunoreactive cells in the epithelium was observed up to 17 days after the denervation, by which time the taste buds had disappeared from the trench wall. The OX62-positive cells were again observed in the connective tissue at 24 and 40 days when taste buds regenerated. The local circulation of OX62-positive cells between the epithelium and connective tissue is suggested. Most of the OX62-positive-cells in the epithelium of circumvallate and foliate papillae were suggested to be gammadelta T cells, since they were round or spindle-shaped. Electron micrographs of OX62-positive cells also indicated that they were lymphocytes. Furthermore, they expressed CD3 but lacked CD4 and CD8 surface markers. A few dendritic cells, which reacted with anti-OX6 antibody, were observed in the circumvallate and foliate papillae in the control and denervated animals, and they were irregular in shape with long cytoplasmic processes. Electron micrographs taken at 6 days showed that the dendritic cells, which were characterized by the presence of Birbeck granules in the cytoplasm, were in contact with lymphocytes. The finding suggests that gammadelta T lymphocytes and dendritic cells in the rat circumvallate and foliate papillae interact with each other to respond to changes such as the presence or absence of taste buds in the epithelium.

Distribution of the neural cell adhesion molecule (NCAM) during pre- and postnatal development of mouse incisors

Developmental changes in the distribution of the neural cell adhesion molecule (NCAM) were investigated in mouse incisors by means of the indirect immunofluorescence method. During the prenatal stages of development, NCAM was predominantly found in the dental follicle, but not in the dental papilla; the results were analogous to the distribution of NCAM during molar development. After birth, the expression of NCAM continued in the tissue between the enamel organ and the alveolar bone on the labial aspect. In contrast, the follicular tissue covering the lingual aspect of the incisor gradually lost NCAM immunoreactivity from its outer zone as it differentiated into the highly organized periodontal ligament. The intermediate zone of the ligament continued to express NCAM-immunoreactivity even in mice of 6 weeks of age. This pattern of NCAM expression was different from that found in molar teeth, where the organized peridontal ligament was NCAM-negative. The dental pulp, in which we previously reported that an NCAM-positive area appeared at later stages of molar tooth development, did not express NCAM immunoreactivity even at the latest stage of development covered in this study. These differences in the distribution of NCAM between the incisors and the molars might be related to the fact that rodent incisors continue to grow throughout the life of the animal.

Apoptosis in mouse taste buds after denervation

Apoptotic cells in the taste buds of mouse circumvallate papillae after the sectioning of bilateral glossopharyngeal nerves were examined by the method of DNA nick-end labeling (TUNEL), together with standard electron microscopy. The taste buds decreased in number and size 3-11 days after denervation and disappeared at 11 days. The TUNEL method revealed only a few positively stained nuclei in normal taste buds but, in those of mice 1-5 days after denervation, the number of positive nuclei had increased to 3-5 times that of taste buds from normal mice. Electron-microscopic observation after denervation demonstrated taste bud cells containing condensed and fragmentary nuclei in a cytoplasm with increased density. The results show that taste bud cells under normal conditions die by apoptosis at the end of their life span, and that gustatory nerve sectioning causes apoptosis of taste bud cells with taste buds decreasing in number and ultimately disappearing.

Phagocytic cells in the taste buds of rat circumvallate papillae after denervation

Phagocytic cells in the taste buds of rat circumvallate papillae after the sectioning of bilateral glossopharyngeal nerves were examined by electron microscopy and immunohistochemistry. Electron micrographs taken 1 day after denervation revealed that flat-shaped cells were present just beneath the taste buds and that their cellular processes extended toward the debris from the degenerating taste buds. At 2-6 days after denervation, long and thin processes of the flat cells surrounded the debris and appeared to have taken them up into the cytoplasm as small vesicles. Evidence for phagocytosis by the flat cells was seen up to 9 days after denervation and again at 24 and 40 days, in correlation to the degeneration and regeneration of the taste buds. Pre-embedding immunohistochemistry using anti-vimentin antibody showed that flat cells strongly reacted with vimentin. Light microscopic immunohistochemistry using anti-macrophage antibodies (ED1, ED2) showed that throughout the post-operative days macrophages were not present underneath or within the taste buds. Most of the ED2-immunoreactive resident macrophages were located in the deep layer of connective tissue, and a few were found in the nerve bundle. ED1-immunoreactive cells were seen in the duct cells of von Ebner's glands and a few were in the trench wall of circumvallate papillae; however, they were also immunoreactive for anti-OX62 antibody, which recognizes dendritic cells. The results indicate that the phagocytic cells of the taste buds are fibroblasts, not macrophages. Moreover, resident macrophages participate in phagocytosis of degenerated nerves together with Schwann cells.

[Involvement of GABAergic and NMDA systems in drug-induced convulsions in mice]

Intravenous (iv) pretreatment of muscimol, a GABAA receptor agonist, inhibited the convulsive effect of bicuculline but not that of picrotoxin, whereas phenobarbital, a Cl ion channel blocker, exhibited both effects. These results suggest that the bicuculline-induced convulsion may be due to Cl ion channel blockade secondary to the direct inhibition of GABAA receptors. CPP and MK-801, competitive and noncompetitive NMDA antagonists, respectively, inhibited both the bicuculline- and picrotoxin-induced convulsion, suggesting that these convulsive effects may also involve activation of the NMDA-Ca ion channel complex, which might link to the GABA-Cl ion channel system. Anticonvulsants phenytoin, carbamazepine and diazepam as well as phenobarbital inhibited the convulsive responses of bicuculline and picrotoxin. Therefore, the anticonvulsive effects of these drugs may involve an activation of the GABA-Cl ion channel function. On the other hand, neither the GABA agonist nor anticonvulsants affected NMDA-induced convulsion. These results also provide evidence that the convulsive effects of bicuculline and picrotoxin may be mediated by indirect activation of NMDA systems through their Cl ion channel-blocking action, whereas the convulsive effects of NMDA may involve the activation of NMDA-Ca ion channel function without the GABA-Cl ion channel activities.