Encephalomyocarditis-virus-induced diabetes model resembles "fulminant" type 1 diabetes in humans.
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Amylases↗
Biomedical subjects
A Shimada
Publications and source records attributed to A Shimada.
Mercury accumulation and its distribution to metallothionein in mouse brain after sub-chronic pulse exposure to mercury vapor.
Previously we found that exposure to mercury vapor effectively induced metallothionein (MT) biosynthesis in rat brain. Although the induction of not only MT-I/II but also MT-III was evident, the induction rate of the latter was much lower than that of the former. The brain of an MT-null mouse lacks MT-I/II, but has MT-III. Here we examined the effects of sub-chronic pulse exposure to mercury vapor on the brain MT in MT-null mice and their wild type controls. MT-null and wild type mice were preliminarily exposed to mercury vapor for 2 weeks at 0.1 mg Hg/m(3) for 1 h/day for 3 days a week, and then exposed for 11 weeks at 4.1 mg Hg/m(3) for 30 min/day for 3 days a week. This exposure caused no toxic signs such as abnormal behavior or loss of body weight gain in the mice of either strain throughout the experimental period. Twenty-four hours after the termination of the exposure, mice were sacrificed and brain samples were subjected to mercury analysis, MT assay, and pathological examination. The MT-null mice showed lower accumulation of mercury in the brain than the wild type mice. Mercury exposure resulted in a 70% increase of brain MT in the wild type mice, which was mostly accounted for by the increase in MT-I/II. On the other hand, the brain MT in the MT-null mice increased by 19%, suggesting less reactivity of the MT-III gene to mercury vapor. Although histochemical examination revealed silver-mercury grains in the cytoplasm of nerve cells and glial cells throughout the brains of both strains, no significant difference was observed between the two strains.
Administration, Inhalation↗
Relationship between the tooth eruption and regional blood flow in angiotensin II-induced hypertensive rats.
OBJECTIVE: The mechanism of action of vasoactive drugs on tooth movement is unknown. The purpose of the present study was to measure simultaneously the axial movement of the mandibular incisor, regional blood flow at the base of the incisor, and systemic arterial blood pressure in angiotensin II-induced hypertensive rats to determine the possible cause of tooth displacement. DESIGN: The measurements were made under artificial respiration with halothane anaesthesia. In the experimental animals, 2.5 microg of angiotensin II in 1 ml of Ringer's solution was infused at 0.83 ml/h for 12 h from the femoral vein. In the control animals, only Ringer's solution was infused. RESULTS: Angiotensin II caused an increase of the mean arterial blood pressure from 86 to 119 mm Hg, and decreases of the eruption rate from 667 to 494 microm/24 h and the regional blood flow from 262 to 214 mV. There was a positive correlation between the eruption rate and regional blood flow, and a negative correlation between the blood pressure and regional blood flow. CONCLUSION: These results suggest that angiotensin II caused constriction of the peripheral vascular smooth muscle resulting in an increase of arterial blood pressure and a decrease of regional blood flow, followed by a decrease of fluid volume and then a reduction of either the pressure within the socket or of the eruptive force. We assume that the regional vascular pressure within the socket plays an important role in determining the position of the rat incisor.
Angiotensin II↗
Effects of age on the stress-strain and stress-relaxation properties of the rat molar periodontal ligament.
OBJECTIVE: We examined the stress-strain and stress-relaxation properties of the periodontal ligament (PDL) in the rat molar at 2, 6, 12, and 24 months of age to elucidate age-related changes in the tooth support function of the PDL. DESIGN: From the dissected left and right mandibles in each rat, a pair of transverse sections (ca. 0.45 mm in thickness) of the first molar was cut at the middle part of the mesial root. We then obtained a load-deformation curve for the PDL, using one of the paired sections. The other section was loaded to as much as 50% of the maximum load as determined from the contralateral section, and keeping the deformation constant for 10 min, a load-relaxation curve was obtained and analysed. RESULTS: The maximum shear stress and tangent modulus decreased between 2 and 24 months of age. As the maximum shear strain increased with age (P < 0.001), the failure strain energy density did not change between 2 and 24 months of age. The stress-relaxation during the 10 min period decreased from 2 to 24 months of age (P < 0.01). The relaxation process of the PDL in each age was well described by a sum of three exponential decay functions. The age-related decrease in the relaxation was found to be mainly due to the increase in the relaxation time for the long-term relaxation component. CONCLUSION: These results indicate that the maximum shear stress and stiffness of the rat molar PDL decrease between 2 and 24 months of age; but its toughness remains unchanged due to an increase in the extensibility. Our findings further indicate that the fluid flow and movements of macromolecules within the stretched PDL fibres during the stress-relaxation decrease with advancing age.
Aging↗
Age-related and regional differences in the stress-strain and stress-relaxation behaviours of the rat incisor periodontal ligament.
Groups of rats were killed at 2, 6, 12, and 24 months of age. From dissected left and right mandibles in each rat, three pairs of transverse sections were cut at the incisal, middle, and basal regions of the incisor. One section in each pair was loaded until failure and a stress-strain curve for the periodontal ligament (PDL) was obtained. The other section was loaded to up to 50% of the maximum shear stress as determined from the contralateral section and then kept at a constant strain for 10 min, to obtain the stress-relaxation curve at the same region of the PDL. The maximum shear stress and toughness increased with age at the incisal region and the maximum shear strain increased with age at the incisal and middle regions. The tangent modulus decreased with advancing age at the middle region. The stress-relaxation during 10 min decreased with advancing age at the incisal and basal regions, but not at the middle region. The relaxation process was well described by a sum of three exponential decay functions, reflecting the short-, medium-, and long-term relaxation components. The age-related decrease in the relaxation was mainly attributable to increases in the ratio and relaxation time of the long-term relaxation component. These results suggest that with advancing age the mechanical strength and toughness of the PDL are enhanced mostly at the incisal region and that the viscous fraction is relatively decreased at the incisal and basal regions along the long axis of the rat incisor.
Aging↗
Novel resistin promoter polymorphisms: association with serum resistin level in Japanese obese individuals.
OBJECTIVES: Resistin, an adipocyte-secreted cytokine recently discovered in mice, has been proposed as a link between obesity and diabetes. We analyzed resistin gene polymorphisms and examined their association with serum resistin level and obesity phenotypes in humans. SUBJECTS AND METHODS: Sixty young, obese, non-diabetic subjects taking no medication were studied. DNA sequencing and genotyping of identified single nucleotide polymorphisms were performed. Associations between polymorphisms and serum resistin level, BMI, body composition, fat distribution, and several indices of insulin sensitivity were examined. Moreover, single nucleotide polymorphisms in the promoter region were examined for their influence on resistin gene transcriptional activity using luciferase reporter vectors. RESULTS: Ten non-coding single nucleotide polymorphisms were found. The -638G>A, -420C>G, and -358G>A polymorphisms in the promoter region showed marked linkage disequilibrium with each other, and were associated with serum resistin level; however, there was no association between these polymorphisms and parameters related to adiposity or insulin resistance. The results of luciferase assay revealed that -638G>A together with the -420C>G polymorphism influenced resistin gene transcriptional activity. CONCLUSION: We found that variability in the serum resistin level might be related to polymorphic variants of the promoter region of the gene.
Adenine↗
Effects of alendronate on restoration of biomechanical properties of periodontium in replanted rat molars.
OBJECTIVE: We examined the effect of the pretreatment of roots with alendronate on the restoration of the support function of the healing periodontal ligament in replanted rat molars. METHODS: The left maxillary first molars were extracted, placed in 0.9% NaCl containing 1 mm alendronate (alendronate group) or 0.9% NaCl (control group) for 5 min, and were replanted into their sockets. Groups of animals were killed at 7, 14, and 21 days after replantation. Normal control rats were also killed on the same days. The force required to extract the replanted or normal tooth from its socket was measured, and a load-deformation curve was developed and analyzed. Micro-computed tomography and histologic analyses were also made. RESULTS: The mechanical properties of the healing periodontal ligament in the alendronate group were gradually restored from 7 to 21 days. However, fractures of the roots and bones during mechanical testing occurred in most of the replanted teeth in the control group at 21 days. The rates of restoration of the mechanical strength, extensibility, stiffness, and toughness for the alendronate group at 21 days were 67, 98, 74, and 68% of the normal controls, respectively. Micro-computed tomography and histologic observations revealed that bone-like structures within the pulp and ankylosis between the roots and socket bones occurred commonly in the control group, but were uncommon in the alendronate group. CONCLUSIONS: Our findings suggest that the pretreatment with alendronate inhibits the formation of abnormal mineralized tissues and results in better restoration of the support function of the healing periodontal ligament in replanted teeth.
Alendronate↗
Protective role of metallothionein in acute lung injury induced by bacterial endotoxin.
BACKGROUND: Metallothionein (MT) is a protein that can be induced by inflammatory mediators and participate in cytoprotection. However, its role in inflammation remains to be established. A study was undertaken to determine whether intrinsic MT protects against acute inflammatory lung injury induced by bacterial endotoxin in MT-I/II knock out (-/-) and wild type (WT) mice. METHODS: MT (-/-) and WT mice were given vehicle or lipopolysaccharide (LPS, 125 microg/kg) intratracheally and the cellular profile of the bronchoalveolar lavage (BAL) fluid, pulmonary oedema, lung histology, expression of proinflammatory molecules, and nuclear localisation of nuclear factor-kappaB (NF-kappaB) in the lung were evaluated. RESULTS: MT (-/-) mice were more susceptible than WT mice to lung inflammation, especially to lung oedema induced by intratracheal challenge with LPS. After LPS challenge, MT deficiency enhanced vacuolar degeneration of pulmonary endothelial cells and type I alveolar epithelial cells and caused focal loss of the basement membrane. LPS treatment caused no significant differences in the enhanced expression of proinflammatory cytokines and chemokines nor in the activation of the NF-kappaB pathway in the lung between the two genotypes. Lipid peroxide levels in the lungs were significantly higher in LPS treated MT (-/-) mice than in LPS treated WT mice. CONCLUSIONS: Endogenous MT protects against acute lung injury related to LPS. The effects are possibly mediated by the enhancement of pulmonary endothelial and epithelial integrity, not by the inhibition of the NF-kappaB pathway.
Animals↗
Inositol 1,4,5-triphosphate receptor protein immunohistochemistry of cerebellar Purkinje cells in two dogs with hypoglycemia.
Immunohistochemical study was performed on cerebellar Purkinje cells of two dogs with hypoglycemia using an antibody against the inositol 1,4,5-triphosphate receptor that is identical to the cerebellar Purkinje cell glycoprotein P(400) (P(400)/InsP(3)R). In the cerebellar neocortex of an acute case of hypoglycemia, the P(400)/InsP(3)R staining of hypoglycemic Purkinje cells was heterogeneous: some peripheral dendrites, including spiny branchlets, were negative and others were stained with various intensities, although Purkinje cells were morphologically intact by hematoxylin and eosin (HE) stain. In a chronic case of hypoglycemia, almost all the dendrites of Purkinje cells of both the neo- and archicortex of the cerebellum were not stained with the P(400)/InsP(3)R antibody. This is in contrast to the normal dog where Purkinje cell bodies, axons, and dendrites, including spiny branchlets, are intensely stained by the P(400)/InsP(3)R antibody. These results suggest that P(400)/InsP(3)R immunolabeling of Purkinje cells decreased, despite their morphology being preserved by HE stain, and that the function of P(400)/InsP(3)R, especially in spiny branchlets that receive inputs originating from axon terminals of parallel fibers, may be impaired in hypoglycemia.
Amino Acid Transport System X-AG↗
Severe involvement of cerebral neopallidum in a dog with hepatic encephalopathy.
This report describes a unique distribution of cerebral cortical necrotic lesion, which was diagnosed as hepatic encephalopathy in a 2-year-old Maltese dog. The dog showed splenocaval shunt and small liver with marked hepatocellular fatty degeneration. Histopathologic examination revealed that diffuse laminar cortical necrosis composed of neuronal necrosis, marked infiltration of gitter macrophages, and astrogliosis were found bilaterally in the dorsolateral area of the cerebrum. No necrotic lesions were observed in the cerebral paleopallium and archipallium, the central gray matter, cerebellum, and brain stem. Astrocytes with large and pale nuclei (Alzheimer type II astrocytes) were apparent throughout the brain. Immunohistochemically, a decrease of immunostains for glutamine synthetase and glutamate transporter antibodies was seen in Alzheimer type II astrocytes and neuropil. This is, to our knowledge, the first report of extensive involvement of cerebral neopallidum in canine hepatic encephalopathy.
Amino Acid Transport System X-AG↗
Isolation of Streptococcus canis from a Japanese raccoon dog with fibrinous pleuropneumonia.
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Animals↗
Hsp27 suppresses the formation of inclusion bodies induced by expression of R120G alpha B-crystallin, a cause of desmin-related myopathy.
The R120G mutation in the small heat shock protein (sHSP) alpha B-crystallin has been identified in a family suffering from desmin-related myopathy. In this study, we characterized the features of transiently expressed R120G alpha B-crystallin in mammalian cells. In addition, we examined interactions of this mutant alpha B-crystallin with Hsp27, another representative sHSP. In HeLa cells, transiently expressed R120G alpha B-crystallin was mainly fractionated in the insoluble fraction, although wild-type alpha B-crystallin was predominantly found in the soluble fraction. In immunofluorescence studies, we found 15-25% of R120G alpha B-crystallin-expressing cells to contain multiple cytosolic inclusion bodies, in which Hsp27 was also localized. When R120G alpha B-crystallin and Hsp27 were transiently co-expressed in HeLa cells, the amount of R120G alpha B-crystallin in the soluble fraction was greater than with expression of R120G alpha B-crystallin alone. Moreover, co-expression resulted in reduced formation of inclusion bodies, suggesting that Hsp27 acts as a molecular chaperone for R120G alpha B-crystallin.
Animals↗
The effects of intrusive loading on axial movements of impeded and unimpeded rat incisors: estimation of eruptive force.
Axial movements of impeded and unimpeded rat mandibular incisors were measured following application and removal of intrusive loads of 1, 2, 5, 10 and 20 mN in a stepwise order at intervals of 1h on erupting teeth. The tooth movements were recorded by a displacement detector under artificial respiration with halothane anaesthesia. The loading and unloading procedures brought about the tooth movements in two steps: an initial rapid movement immediately after application or removal of the load and a subsequent slow and gradual movement. The initial rapid intrusive or extrusive tooth movements were significantly greater in the unimpeded than in the impeded teeth at the same load. The forces to stop extrusive tooth movements, estimated from the formula of regression lines showing correlations between the intrusive loads from 0 to 5 mN and tooth movements (microm/30 min), were 4.2 mN in the impeded and 2.9 mN in the unimpeded incisors. We suggest that repeated shortenings of the rat incisor did not cause an increase in the eruptive force and that changes in the resistance of the periodontal ligament predominantly regulate the axial movement of the rat incisor.
Animals↗
Healing in transplanted teeth with periodontal ligament cultured in vitro.
Regeneration of connective tissue attachment is the ultimate goal of periodontal therapy. It has been suggested that periodontal ligament cells possess the potential to create new connective tissue attachment. However, as cells from gingiva and alveolar bone occupy the root surface during initial wound healing, population by periodontal ligament cells is limited in vivo. We have been developing a new periodontal regeneration technique using in vitro tissue culture of periodontal ligament remaining on a periodontally involved root. The purpose of this study was to examine the periodontal healing after transplantation of teeth with reduced periodontal ligament that had been cultured in vitro. Twenty-five incisors from four beagles were used. After the teeth were extracted, the periodontal ligament and cementum were removed from coronal part of the roots and the roots were planed. The periodontal ligament of the apical part was retained. Fourteen teeth of the experimental group were transplanted following culture for 6 weeks. Eleven teeth of the control group were similarly prepared and immediately transplanted without tissue culture. Four weeks after transplantation, the specimens were prepared for histological analysis. Downgrowth of junctional epithelium on the root of experimental group was significantly less than control. Most of the root planed surfaces of experimental group were covered with periodontal ligament fibers oriented parallel or inclined to the root surfaces and limited new cementum formation was observed near the apical end of the planed root. There was no significant difference between groups in observations on the root surface with remaining periodontal ligament. From the above results, it was concluded that periodontal tissue culture of teeth with root planed surface and remaining periodontal ligament could reduce the extent of epithelium downgrowth and increase connective tissue adhesion on the root planed surface, as well as minimize damage to remaining periodontal ligament, after transplantation of teeth.
Animals↗
Late infantile Hirschsprung disease-mental retardation syndrome with a 3-bp deletion in ZFHX1B.
A 48-year-old woman with late infantile onset mental retardation developed megacolon. Although the patient had no typical clinical features of Hirschsprung disease-mental retardation syndrome, a new 3-base pair deletion, eliminating an Asn, was identified in the responsible gene ZFHX1B. This suggests that screening for ZFHX1B mutations is warranted even in the absence of typical clinical features of the syndrome.
Cloning, Molecular↗
Effect of preincubation of cryopreserved porcine epididymal sperm.
Preincubation of spermatozoa is important for capacitation and successful fertilization in vitro. The effects of preincubation time on frozen-thawed boar epididymal spermatozoa as measured by sperm motility, acrosomal integrity and fertilization ability in vitro were examined. Epididymal spermatozoa were collected from three Large White boars and frozen. The thawed spermatozoa were preincubated for 0, 15, 30, 60 and 120 min. Their motility was evaluated by a sperm motility analyzer and then the sperm motility indexes (SMIs) were calculated. The status of their acrosomal integrity was evaluated by triple-staining. Then, their fertilization ability was examined by in vitro fertilization (IVF) using porcine oocytes matured in vitro. SMIs of spermatozoa and the incidences of acrosome-intact live spermatozoa from the three boars were high (21-39 for SMI and 50-61% for acrosome-intact live spermatozoa) just after thawing, but both decreased as the duration of preincubation was prolonged (2-10 and 23-40%, respectively). The incidences of sperm penetration were high (61-89% of inseminated oocytes) when the sperm were preincubated for 0-60 min. However, sperm penetration decreased as the preincubation period was prolonged to 120 min. The degree of this decrease differed depending upon the boar from which the spermatozoa were obtained (10-72%). When the two parameters, sperm motility and acrosomal integrity, were analyzed statistically, the latter parameter rather than the former one showed a significant effect on penetration ability in vitro after each duration of preincubation. These results suggest that preincubation of frozen-thawed boar epididymal spermatozoa is not required for IVF and also that the maintenance of acrosomal integrity in unreacted status, rather than the maintenance of sperm motility, is important for fertilization ability after thawing and during preincubation of boar epididymal spermatozoa.
Acrosome↗
Myofiber expression of class I major histocompatibility complex accompanied by CD8+ T-cell-associated myofiber injury in a case of canine polymyositis.
A 7-year-old female Labrador Retriever dog showed extreme muscular weakness, muscle wasting, dysbasia, and mild dysphagia. An elevated value of creatine kinase (335 IU/liter) in the serum was detected. Electromyographic findings included increased insertional activity, fibrillation potentials, and bizarre high-frequency repetitive potentials. Histopathologic examination of skeletal muscles revealed myofiber necrosis and phagocytosis, regeneration of myofibers, and perivascular, perimysial, and endomysial infiltrations of lymphocytes, macrophages and plasma cells. Immunohistochemical evaluation demonstrated that infiltrative cells in the early stage of myositis were CD8+ T-cells and that an increased expression of major histocompatibility complex (MHC) class I was apparent on the surface of nonnecrotic muscle fibers. In contrast, many CD3+ cells (T cells) and HLA-DR-positive macrophages and B lymphocytes were found in the severely affected areas. These results suggest that both expression of MHC class I and CD8+ T-cell infiltration may play an important role in initiation of myositis. These histopathologic findings resemble those reported in naturally occurring polymyositis in humans.
Animals↗
Cliniconeuropathologic findings of familial frontal lobe epilepsy in Shetland sheepdogs.
We examined an epileptic focus by electroencephalography (EEG) by using an international 10-20 electrode system in 11 Shetland sheep dogs affected with familial idiopathic epilepsy. We also performed an evaluation of the amino acids in the cerebrospinal fluid (CSF) and a pathologic examination of the brains of 8 dogs that died from status epilepticus. Continuous electroencephalography demonstrated that an epileptic focus was initially detected in the frontal lobe, particularly the internal area, and that paroxysmal foci developed diffusely in other lobes of affected dogs with recurrent convulsions. The EEG analyses indicated spike and sharp wave complexes, which were considered to be paroxysmal discharges. An increased value for glutamate or aspartate was found in the CSF of some epileptic dogs. Histologically, acute neuronal necrosis and astrocytosis were distributed predominantly in the cingulate cortex and internal area of frontal cortex, less frequently in other areas of the cerebrum. The results of this study suggest that, initially, the dogs have an epileptic focus in the frontal lobe, and that the focus extends gradually to other areas of the cerebrum. Based on the distribution of neuronal necrosis and astrocytosis, acute neuronal damage may be related to the superexcitation of neurons following epilepsy.
Amino Acids↗