Biomedical subjects

N Goto

Publications and source records attributed to N Goto.

At least 127 records · Page 7Linked to original sources

PubMed1997

Age-related changes in susceptibility of mice to low-virulent mouse hepatitis virus (MHV-2-CC) infection.

This study was performed to examine mouse age-dependent changes in susceptibility to MHV-2-CC-infection and participation of macrophages in such changes in BALB/c mice. One-week-old mice were fully susceptible (mortality, 100%), 2-week-old semi-susceptible (36%), and 3- and 4-week-old fully resistant (0%) to MHV-2-CC, respectively. Such age-dependent differences corresponded well with the differences in the virus titers in the liver, spleen and blood and in the severity of liver lesions. In 1-week-old mice with peritoneal exudate cells (PEC) transferred from 4-week-old mice and infected with MHV-2-CC, a slight prolongation of survival time was recorded, although there was no difference in mortality. In 3-week-old mice infected with MHV-2-CC after silica-treatment to suppress macrophages, there was no significant change in susceptibility. In macrophages infected with MHV-2-CC in vitro, the virus replicated better in macrophages obtained from younger mice. These results suggest that macrophages may play a small role in the age-related development of resistance to MHV-2-CC infection in BALB/c mice.

Aging↗

PubMed1997

Protective effects of a novel quinone derivative, E3330, on mouse hepatitis virus (MHV)-induced chronic hepatitis in athymic nude mice.

In this experiment, we examined the protective effects of a novel quinone derivative, E3330, on MHV-2cc-induced chronic hepatitis in athymic nude mice for up to 3 weeks after virus infection. The daily dose of 25 mg/kg b.w. suppressed the viral replication in the liver and the progression of hepatic lesions. The expansion of small focal lesions at 1 week after viral inoculation (WAI) was suppressed at 2 WAI, and the lesions were still small at 3 WAI in E3330-administered group, whereas small focal lesions at 1 WAI were expanded at 2 WAI to fuse with each other at 3 WAI in the control group. E3330 therefore showed protective effects on MHV-2cc-induced chronic hepatitis in athymic nude mice, but further studies are needed to analyze the mechanism.

Administration, Oral↗

PubMed1997

Morphometric comparison of the motor trigeminal neurons.

Comparative morphological and morphometric studies of the motor trigeminal nucleus (MTN) were carried out on the brains of an alligator, a human being and a rat for the first time. Differences in neurons regarding sizes, areas, numbers, column volumes, neuropil indices and circulatory ratios were found. The results showed that the positions and shapes of the MTN were different, and the shapes of motor neurons were different, too. The average area of motor trigeminal neurons was the largest in the alligator, compared with the area in the human being, and the rat; the number of neurons and the column volume of MTN were the largest in the human being. As for the neuropil indices, the value was in descending order: alligator, human being and rat; whereas for the circulatory ratio of neuronal cell bodies, the order was rat, alligator, and human being. We conclude that the size of motor neurons in the MTN may be related to the power of masticatory muscles, and there may be a connection between jaw sizes and shapes and sizes of the motor neurons in the MTN.

Alligators and Crocodiles↗

PubMed1997

Myelinated nerve fibre analysis of the human small splanchnic nerve.

The aim of the present study is to analyse nerve fibres of the human small splanchnic nerve in relation to the ageing process. The analysis was conducted with the use of a new staining method that makes it possible to discriminate various structures of the nervous tissue. An image-analysing digitiser, a microscope with a drawing tube and a personal computer for storing data and performing statistical analyses were employed in this study. We examined 30 human small splanchnic nerves which were taken from cadaver specimens (20 males and 10 females) aged from 44 to 96 years. Our report may provide a first information concerning the ageing process of the human small splanchnic nerve. The results indicate that a decrease in transverse area and perimeter of myelinated axons in one of the important changes occurring in the human small splanchnic nerve with the ageing process.

Adult↗

PubMed1997

Morphometric analyses of axons in the lateral corticospinal tract with ageing process.

Morphometric analyses were carried out to reveal a relation between age and axonal changes in the lateral corticospinal tract (LCST) at the L1 level of the human spinal cord. Histological preparations of the spinal cord were made after embedding in celloidin to stain with Luxol fast blue-periodic acid-Schiff-hematoxylin or Klüver-Barrera methods. The number, average transverse area, total area and diameter of axons of the LCST were counted and measured using an image-analyser combined with a computer. The morphometric analyses revealed that (1) there was a significant decrease in the axonal number of the LCST with age (p < 0.001); (2) the axons were not partially nor completely accompanied by surrounding myelin sheaths, and increased in number with age; (3) the diameter and average area of axons in the LCST became significantly reduced with age (p < 0.01); (4) the total area decreased significantly with age in a unit area of 2,700 microns2; and (5) the circularity ratio showed no significant change with age.

Adult↗

PubMed1997

5-Azacytidine (5Az) induces apoptosis in PC12 cells: a model for 5Az-induced apoptosis in developing neuronal cells.

Our previous in vivo and in vitro studies showed that 5-azacytidine (5Az), a cytidine analog, induced apoptosis in developing neuronal cells in mice. To develop a system in which the precise molecular mechanism of 5Az-induced apoptosis in developing neuronal cells could be elucidated, we carried out the present study with PC12 cells. These cells are derived from a rat pheochromocytoma and extrude neurites in response to nerve growth factor (NGF). Light microscopy showed dose-dependent pyknotic and karyorrhectic changes in undifferentiated PC12 cells. Although they were less sensitive to 5Az, NGF-treated differentiated cells showed the same changes. Analysis by the TUNEL method (an in situ method for the detection of apoptosis) showed positive signals in the pyknotic and fragmented nuclei of these cells. Transmission electron microscopy revealed margination, segmentation, and condensation of nuclear chromatin, cell body shrinkage, and cytoplasmic vacuolization. Scanning electron microscopy demonstrated bleb formation on the cell surface. These pathomorphological changes are typical of apoptosis. 5Az seemed to affect cells that were in the proliferative stage; when the cells were terminally differentiated, their sensitivity to 5Az appeared to decline. PC12 cells could be used as a pathomorphological and biochemical model for studies of 5Az-induced neuronal cell apoptosis at the molecular and genetic level.

Animals↗

PubMed1997

Factors affecting induction of neurological disorder in mice by PVC viruses and the sequence of env-LTR region of PVC441.

PVC111, PVC211, PVC321 and PVC441 cause neurological disorders associated with tremor and paralysis in rats. We tested the pathogenicity of these viruses in mice. Although histopathological studies revealed spongiform degeneration in the spinal cords of NFS mice infected with each PVC virus, only PVC441 caused a high incidence of tremor and paralysis. Further studies with PVC441 revealed dose and age dependence for tremor induction. In contrast to NFS mice, BALB/c, DBA/2 and C57BL/6 mice infected with PVC441 virus showed no neurological symptoms, although the virus replicated in each strain to titers within 5-fold of the titer in NFS mice. Despite absence of neurological symptoms, high degree of neuronal degeneration in the lumbar spinal cord was found in PVC441-infected BALB/c mice. Low degree of neuronal degeneration was found in PVC441-infected DBA/2 or C57BL/6 mice. Genetic crosses of these resistant mice with susceptible NFS mice indicated that resistance to PVC441-induced tremor induction was dominant in all strains and suggested that various host genes may control the susceptibility of mice to tremor induction by PVC441 virus. Sequencing of env-LTR region of PVC441 revealed an intermediate character between PVC211 and F-MuLV.

Animals↗

PubMed1996

Molecular characterization of feline immunodeficiency virus genome obtained directly from organs of a naturally infected cat with marked neurological symptoms and encephalitis.

Feline immunodeficiency virus (FIV) was first isolated from cats with immunodeficiency syndrome. Recently, neurological abnormalities and brain lesions were shown in cats infected with FIV. To investigate the FIV genome associated with central nervous system (CNS) lesions, proviral DNA sequences from the V3-V6 region of the FIV env gene were directly amplified from uncultured necropsy tissues of a 2-year-old naturally FIV-infected cat with marked neurological symptoms and encephalitis. By in situ hybridization, FIV RNA was detected mainly in the astrocytes. Fifteen clones isolated from cerebrum, bone marrow and lymph node samples showed only a small number of mutations or deletions in this region. A representative clone, JN-BR1, was distantly related to the previous Japanese strain (TM2) belonging to the subtype B. However, it was relatively close to the Petaluma strain which is known to infect feline brain-derived culture cells and induce brain lesions in inoculated cats. By phylogenetic analysis, the JN-BR1 strain was placed in subtype A that included Petaluma strain and several other American and European strains. The JN-BR1 strain derived from brain with encephalitis in this study and the Petaluma strain may share a common genetic structure that is related to their neuropathogenicity.

Amino Acid Sequence↗

PubMed1996

Senile plaques in very aged cats.

Senile plaques were found in the cerebral cortices of three very aged cats (more than 18 years old). The plaques consisted of a coarse assembly of silver staining-positive materials, and was morphologically different from the well-known classical, primitive, and diffuse plaques. Congophilic amyloid angiopathy was observed in a few cortical arterioles of the oldest cat (20 years old). The senile plaques and a few cortical blood vessels were immunopositive for amyloid beta-protein (A beta). A beta-positive materials were also sparsely distributed in the cortical neuropil but did not form senile plaques there. These findings should help to clarify the development of senile plaques and the early stage of A beta deposition.

Aging↗

PubMed1996

Apoptosis in the aged dog brain.

Apoptosis similar to that seen in Alzheimer's disease patients was found in the brain of aged dogs by the TUNEL method of detecting in situ DNA fragmentation. Apoptosis was observed in both neurons and glial cells, and was morphologically characterized by round and swollen cytoplasm and aggregated nuclear chromatin, although these changes were slight. Neurons and astrocytes in the gray matter and oligodendrocytes in the white matter were affected. The number of ApopTag-positive brain cells increased slightly with age, but was not correlated to the number of senile plaques. A good correlation between the number of ApopTag-positive cells and the dementia index was clearly found. The present study indicates that brain cell apoptosis could account for dementia in aged dogs and suggested that aged dogs may be useful as a simplified animal model for Alzheimer's disease in man.

Aging↗

PubMed1996

In vitro induction of apoptosis of developing brain cells by 5-azacytidine.

We had found that 5-azacytidine (5Az), a cytidine analogue, could produce apoptosis of fetal developing neuronal cells on the day after injection of the agent into dams by the i.p. route at 11 days of gestation. To make a further understanding of the phenomenon by comparing the results between the in-vivo and in-vitro system, this study was carried out. Entire cephalic parts of the fetuses were collected aseptically at days 11 of gestation and a mixed culture, consisting of neuronal and mesenchymal cells, was established after one week of incubation. The silver-staining revealed pyknotic nuclei and loss of dendrites of neuronal cells in the lower (5 micrograms/ml) dose of the 5 Az-added group. SEM showed shrinkage of the cell body and blebbing formation on the cell surface. TEM evoked margination, segmentation and complete condensation of the nuclear chromatin. Scattered positive signals identical to the apoptotic cells and aggregated fragmented DNA were detected by the TUNEL method. Treatment of higher doses of 5Az (50 and 500 micrograms/ml), however, induced necrosis of both neuronal and mesenchymal cells, light- and electron-microscopically. On the contrary, the control group (0 microgram/ml) showed normal development of neuronal cells and very few positive signals of physiological apoptosis. It was concluded that 5Az could induce apoptosis of developing neuronal cells at lower doses, but necrosis of a wider cell population at higher doses. Involvement of hypomethylation, an important biochemical function of 5Az, in apoptosis was also speculated.

Animals↗

PubMed1996

Rapid identification of mutans streptococcal species.

Mutans streptococci are considered the predominant pathogens in dental caries. Three methods, i.e. dot blot hybridization analysis, PCR analysis and SDS-blue dextran-PAGE, were examined for identifying mutans streptococcal species. In dot blot hybridization, DNA probe derived from the dextranse gene (dexA) of Streptococcus mutans hybridized with different intensities under the condition of low stringency against each species of mutans streptococci although the dexA probe was specific for S. mutans under the condition of high stringency. Oligonucleotide primers for polymerase chain reaction (PCR) were designed on the basis of the dexA DNA sequence. The primers amplified species-specific PCR products in the reference species (15 strains of 5 species) of mutants streptococci. An electrophoretic profile of dextranases from the mutans streptococci on SDS-blue dextran-PAGE also showed species-specific behavior. These results suggest that the three identification methods examined here are useful for distinguishing the species of mutans streptococci and also indicate that PCR analysis is suitable for simple, rapid and reliable identification of mutans streptococcal species.

Bacterial Typing Techniques↗

PubMed1996

Nucleotide sequence of the SrRNA gene and phylogenetic analysis of Trichomonas tenax.

The small subunit ribosomal RNA (SrRNA) gene of Trichomonas tenax ATCC30207 was amplified by PCR and the 1.55-kb product was cloned into plasmid vector pUC18. Four clones were isolated and sequenced. The insert DNAs were 1,552 bp long and their G+C contents were 48.1%; three of them had exactly the same DNA sequences and one had only one nucleotide change. A representative SrRNA sequence was analyzed and a phylogenetic tree was estimated by the neighbor-joining (NJ) method. Among the protists examined, T. tenax was placed as the closest relative of Tritrichomonas foetus, as expected from the traditional taxonomy. The total homology between the two SrRNA sequences was 89.2%.

Animals↗

PubMed1996

Direct detection of Streptococcus mutans in human dental plaque by polymerase chain reaction.

Streptococcus mutans is an etiological agent in human dental caries. A method for the detection of S. mutans directly from human dental plaque by polymerase chain reaction has been developed. Oligonucleotide primers specific for a portion of the dextranase gene (dexA) of S. mutans Ingbritt (serotype c) were designed to amplify a 1272-bp DNA fragment by polymerase chain reaction. The present method specifically detected S. mutans (serotypes c, e and f), but none of the other mutans streptococci: S. cricetus (serotype a), S. rattus (serotype b), S. sobrinus (serotypes d and g), and S. downei (serotype h), other gram-positive bacteria (16 strains of 12 species of cocci and 18 strains of 12 species of bacilli) nor gram-negative bacteria (1 strain of 1 species of cocci and 20 strains of 18 species of bacilli). The method was capable of detecting 1 pg of the chromosomal DNA purified from S. mutans Ingbritt and as few as 12 colony-forming units of S. mutans cells. The S. mutans cells in human dental plaque were also directly detected. Seventy clinical isolates of S. mutans isolated from the dental plaque of 8 patients were all positive by the polymerase chain reaction. These results suggest that the dexA polymerase chain reaction is suitable for the specific detection and identification of S. mutans.

Animals↗

PubMed1996

Immunohistochemical characteristics of the constituents of senile plaques and amyloid angiopathy in aged cynomolgus monkeys.

In this study, we immunohistochemically examined the several constituents of senile plaques (SPs) and cerebral amyloid angiopathy (CAA) in aged cynomolgus monkeys. Apolipoprotein E (apoE) deposited in all mature plaques and CAA, and in half of the diffuse plaques. Alpha-1-antichymotripsin (alpha ACT) deposited in half of the mature plaques and in one third of the CAA. Amyloid precursor protein (APP), ubiquitin (Ub), and microtubule-associated protein-2 (MAP-2) accumulated in the swollen neurites of mature plaques. Glial fibrillary acidic protein (GFAP) was detected in the astrocytes and their processes surrounding the mature plaques. Tau was detected in neither the SPs nor CAA. Therefore, mature plaques involved extracellular A beta, apoE, and alpha ACT, and also astrocytes and swollen neurites. However, diffuse plaques involved only extracellular A beta and apoE. Since these features, except for tau, were consistent with those in humans, this animal model will be useful for studying the pathogenesis of cerebral amyloid deposition.

Aging↗

PubMed1996

[An outbreak of influenza A (H3N2) in a nursing home].

In the nursing home belonging to our hospital, an outbreak of influenza A (H3N2) occurred in January 1995, and we studied 23 elderly residents with influenza A infection. Twenty three residents with influenza A (8 males and 15 females) ranged in age from 67 to 95 years (average 83.1 years), 91.3% of them were bedridden. And all had underlying medical conditions with neurologic, cardiac, orthopedic, being the most frequent. The most common complaints were fever (100%), followed by cough (95.7%), sputum (60.9%), but sore throat was significantly less frequent. Influenza A virus was isolated from throat swab specimens from 6 of 18 ill patients. Fourteen persons were hospitalized and 2 of them had pneumonia, but nobody died. The levels of CRP, WBC were significantly high in the influenza group, as compared to the non influenza group. So this result suggested that influenza A infection among elderly subjects was apt to cause bacterial infection such as bronchitis and pneumonia. This outbreak was caused by contact from the staff to residents, so we think the health care of the staffs and prevention of influenza should be a high priority in nursing homes.

Aged↗

PubMed1996

Detection and identification of Entamoeba gingivalis by specific amplification of rRNA gene.

A pair of oligonucleotide primers were designed from the nucleotide sequence of the gene encoding the small subunit ribosomal RNA (SrRNA) of the oral protozoan parasite Entamoeba gingivalis. The primers amplified a 1.4-kb DNA fragment by polymerase chain reaction and were specific for Entamoeba gingivalis but not for other protozoa, oral protists and bacteria, or human leukocytes. With this method, the DNA from as few as 30 cells of Entamoeba gingivalis could be detected. These results suggest that this approach is applicable to the detection and identification of Entamoeba gingivalis in the human oral cavity.

Animals↗

PubMed1996

Demonstration of the nasal septal branches of the sphenopalatine artery by use of a new intravascular injection method.

We injected a new injection material into the external carotid artery using a new method, which led to the successful demonstration of the nasal septal branches of the sphenopalatine artery in human cadavers. The result shows the trunk of the artery divided into three main branches, the upper two of which run toward Little's area. We believe that the knowledge of septal branches, shown in a photograph, is very useful, not only for nasal treatment, but also for anatomic demonstration to students.

Aged↗