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Biomedical subjects

M Tajima

Publications and source records attributed to M Tajima.

At least 127 records · Page 7Linked to original sources
PubMed1994

Papovavirus detection by electron microscopy in the brain of an elderly patient without overt progressive multifocal leukoencephalopathy.

Virions resembling papovavirus were demonstrated in glial cells in the brain of an aged patient without overt progressive multifocal leukoencephalopathy. The patient was not in a severely immunocompromised state. On histological examination, only a few tiny incomplete necrotic foci were found in the subcortical area. These foci were widely dispersed. Rare, swollen oligodendroglial cells and astrocytes in which papovavirus capsid protein (VP-1) was demonstrated immunohistochemically were present around the foci. The two typical types of virus particles i.e. 35 to 40 nm round particles and elongated particles, were observed in the nuclei of the swollen glial cells. The latter were in the minority. Distinct crystals were also found in the nuclei. The centre-to-centre distance of the particles in the crystals, about 40 nm, and the electron-opaque spots of the round-shaped virions and of the elongated particles, were indicative of structural subunits of papovavirus capsids. This case provides further evidence that papovavirus, possibly JC virus, may be reactivated in the brains of aged patients who are not in an immunocompromised state.

Aged↗
PubMed1994

Biological behaviour and morphological characteristics of a transplantable tumour (MM-KMY) derived from a malignant meningioma in an F344 rat.

A subcutaneously transplantable meningeal tumour (MM-KMY) was derived from a spontaneous malignant meningioma which developed in the cerebellar meninges of a female F344 rat. MM-KMY was subjected to 25 serial passages in syngeneic male and female rats. The transplants grew in 8 weeks into a nodule with an average diameter of 5.7 cm and average weight of 125.2 g. MM-KMY possessed large cysts containing fluid and necrotic tissue. Metastases frequently occurred in the lungs of MM-KMY-bearing rats. Histologically, both the original tumour and MM-KMY consisted of round to fusiform neoplastic cells of varying size, with nuclear pleomorphism. Mitotic figures occurred frequently. MM-KMY cells were positive for vimentin. Ultrastructurally, the cells showed desmosome-like structures, interdigitating processes and cytoplasmic intermediate filaments, suggesting an arachnoid cell origin. Abnormal accumulations of hyaline droplets in renal tubular epithelial cells were frequently observed in MM-KMY-bearing rats, suggesting overload of low molecular proteins in the renal tubules. The droplets gave a faint immunoreaction for lysozyme. The relation between the appearance of renal tubular hyaline droplets and the growth of MM-KMY remains to be determined. MM-KMY may prove useful for studying the biological behaviour and morphogenesis of meningeal tumours.

Animals↗
PubMed1994

Acute ischaemic preconditioning and chronic hypoxia independently increase myocardial tolerance to ischaemia.

OBJECTIVE: Myocardial adaptation has been reported to result from mild but chronic ischaemia in the hearts of patients with coronary artery disease. The aim of this study was to test the hypothesis that the responses of the chronically hypoxic myocardium to an episode of severe ischaemia, or the effects of acute ischaemic preconditioning on myocardial function after subsequent fatal ischaemia, may differ between the normoxic and the chronically hypoxic myocardium. METHODS: A rat model of three week hypoxia (10% O2) was used to simulate tissue hypoxia caused by chronic ischaemia. In isolated isovolumetrically contracting hearts perfused with oxygenated erythrocyte-containing Tyrode solution, systolic and diastolic functions during a 15 or 20 min period of ischaemia and reperfusion were measured in the normoxic control and chronically hypoxic groups. RESULTS: Increases in diastolic pressure during ischaemia were smaller and the recovery of developed pressure during reperfusion was greater in the chronically hypoxic group than in the normoxic group. The hearts of the normoxic group never recovered from ischaemic damage after 20 min ischaemia. The beneficial effects of acute preconditioning with 5 min ischaemia on myocardial function were observed after 15 min ischaemia in the normoxic group, and during and after 20 min ischaemia in the chronically hypoxic group. Changes in lactate production and high energy phosphates could not explain the increased tolerance to ischaemia in the chronically hypoxic group. CONCLUSIONS: Chronic hypoxia increased myocardial tolerance to ischaemia, and acute ischaemic preconditioning increased the tolerance further. Thus chronic hypoxia and acute ischaemic preconditioning independently activate protective mechanisms against ischaemia; the mechanisms may differ between the two types of insult.

Acute Disease↗
PubMed1994

Effects of Chinese herbal medicines on DNA-synthesizing enzyme activities in mammary tumors of mice.

Sho-saiko-to (SST) and Juzen-taiho-to (JTT), Japanese modified Chinese herbal prescriptions, suppressed the activities of thymidylate synthetase and thymidine kinase involved in de novo and salvage pathways for pyrimidine nucleotide synthesis, respectively, in mammary tumors of SHN mice with the reduction of serum prolactin level. These results indicate that SST and JTT may have the antitumor effects on mammary tumors.

Animals↗
PubMed1994

Production of choleretic substances in the capitulum, leaf and stem of Artemisia capillaris during the plant growth cycle.

Five Artemisia capillaris plants were selected at random from among a bed of twenty plants cultivated in a field for one year. Several branches were collected from each plant once a month, except in August and October, when two collections were made during budding and flowering. Each organ (leaf, stem, and capitulum) was separated from the branch and dried, and later analyzed for capillarisin and 6,7-dimethylesculetin content by high-performance liquid chromatography (HPLC). The capillarisin and 6,7-dimethylesculetin content reached maximum levels in the leaf just before the appearance of flower buds at end of July. About one month later, at the end of August during budding and flowering, capillarisin content in the capitulum reached a peak and then decreased. On the other hand, 6,7-dimethylescuretin content reached a maximum at the beginning of September, two weeks after the capillarisin maximum. The results suggest that the most appropriate time to harvest A. capillaris for use as a crude drug is between the flower bud stage and early flower stage, from late August to early September.

Calibration↗
PubMed1994

Changes with age of mammary glands in male and female soft-furred rat, Millardia meltada, in relation to prolactin and testosterone.

The soft-furred rat, millardia (Millardia meltada), is characterized by the development of androgen-dependent mammary tumours only in males. The age-related changes of the activities of thymidylate synthetase (TS) and thymidine kinase (TK), which contribute to DNA synthesis through de novo and salvage pathways, respectively, and structure in the mammary glands were studied in both males and females of this species between 5-28 months of age. While TK activity had no relation to age, TS activity decreased with age in males. In the females, TK activity increased with age, but not TS activity. These enzyme activities were generally higher in females than in males. The mammary glands of both sexes consisted of fine ducts with small end-buds and the glands of males contained mostly black pigments at any age examined. In either males or females, serum levels of prolactin and testosterone related little with age, DNA synthesizing enzyme activities or structure of the mammary glands. Furthermore, elevation by pituitary grafting of circulating prolactin affected neither DNA synthesizing enzyme activities nor structure of mammary glands in both sexes. The histological structures of adrenal, testis, ovary, ventral prostate and uterus of millardia were essentially similar to those of mice or rats.

Adrenal Glands↗
PubMed1994

Pathogenesis of highly virulent infectious bursal disease virus infection in intact and bursectomized chickens.

The pathogenesis of highly virulent infectious bursal disease (IBD) virus (IBDV) infection was studied using 6-week-old intact and 5-week-old bursectomized chickens inoculated with highly virulent strain 90-11 or reference strain I. Chickens inoculated with 10(0.7) EID50 of strain 90-11 showed neither clinical signs nor lesions during the 4-day observation period. In contrast, birds inoculated with 10(2.7) or 10(4.7) EID50 developed severe clinical IBD, as well as gross and histologic lesions, typical of IBD, and produced IBDV antigen demonstrable by immunostaining in the bursa of Fabricius (BF), thymus, spleen and bone marrow from day 2 post-inoculation (PI) onwards. The antigen was also detected by the agar-gel precipitation and latex microsphere agglutination tests in a bursal suspension of these birds from day 2 or day 3 PI on. Birds inoculated with 10(6.1) EID50 of strain I developed only slight clinical signs at day 4 PI. Their lesion- and antigen-scores in the BF were almost the same as those in virulent strain-infected chickens, but lesion- and antigen-scores in the other organs were negligible. Bursectomized chickens inoculated with strain 90-11 did not develop clinical IBD despite the presence of infection that was evidenced by histologic lesions in the thymus and spleen as well as IBDV antigen demonstrable by immunostaining in these organs.

Animals↗
PubMed1994

Morphology of spontaneous Harderian gland tumors in aged B6C3F1 mice.

Spontaneous Harderian gland tumors in B6C3F1 mice were found in 18 (3.1%) (one male had bilateral tumors) of 589 males and 18 (3.0%) of 609 females. The tumor-bearing mice ranged in age from 73 to 109 weeks. These tumors comprised 32 adenomas (86.5%), four adenocarcinomas (10.8%) and one pleomorphic tumor (2.7%); the adenomas were classified, based on the growth patterns, into 17 papillary, nine cystic papillary, five acinar and one cystic types. Two adenocarcinomas grew papillary and invaded surrounding tissues, and the other two grew acinously. The pleomorphic tumor consisted of pleomorphic cells some of which had a keratin-positive epithelial feature and acini lined by atypical epithelial cells.

Adenocarcinoma↗
PubMed1994

An outbreak of porcine reproductive and respiratory syndrome in Japan.

An emerging swine disease principally involving periweaning piglets was examined. The disease was clinically characterized by lethargy, fever, emaciation, coughing, and severe abdominal breathing, hence colloquially named "Heko-heko" disease. The consistent lesions in affected piglets were diffuse interstitial pneumonia with pronounced type II pneumocytic proliferation, meningoencephalitis, and regression of the lymphoid tissues. The causal virus was isolated in primary porcine lung cell (PLC) cultures from various organs of affected piglets and showed serological relatedness to the European porcine reproductive and respiratory syndrome (PRRS) virus. Numerous virus particles, measured about 49 nm in diameter, were detected in the cytoplasm of alveolar epithelial cells and pulmonary macrophages in PLC cultures infected with the isolate. The condition could be experimentally reproduced in conventional piglets by intranasal inoculation with the isolate and the virus was reisolated from the infected animals.

Animals↗
PubMed1994

Phylogenetic comparison between archetypal and disease-associated JC virus isolates in Japan.

We examined the phylogenetical correlation between two types of JC virus (JCV) isolates, archetypes derived from the urine of nonimmunocompromised individuals and PML-types derived from the brain of patients with progressive multifocal leukoencephalopathy (PML) in Japan. A phylogenetic tree was constructed for eight JCV isolates, five PML-types obtained in this and previous studies and three representative archetypes, from DNA sequence data on the VP1 (major capsid protein) gene. The eight isolates were divided into two major groups, named subtypes MY and CY after the representative archetypal isolates. Four of five PML-type isolates belonged to subtype MY, and the other one to subtype CY. Isolates belonging to subtype MY were further divided into two groups; one group containing archetype MY and three PML-types and the other one containing archetype YI and a PML-type. These findings, together with those in our previous study that correlated various JCV isolates in the world provide evidence for the hypothesis that JCVs associated with PML may have been generated from archetypal JCVs persisting in the patients.

Base Sequence↗
PubMed1994

[Gene transfer to airway epithelial cells: current status and future direction].

Advances in recombinant DNA technology and molecular and cellular biology have made it feasible to introduce genes into living cells. The most sophisticated gene transduction methods have bee applied to gene therapy strategies for the potential treatment of genetic diseases. In regard to lung diseases, alpha 1-antitrypsin deficiency and cystic fibrosis, the most common hereditary lung disorders in Caucasians, have been targeted for gene therapy. To date, gene therapy studies have been confined to ex vivo strategies for treatment of ADA deficiency with retroviral vectors. However, there are two major obstacles to gene transfer to the bronchial epithelium. First, bronchial epithelium, such as that with ciliated cells, is terminally differentiated, and does not divide rapidly. Second, the complex architecture of the lung precludes replacing the existing bronchial epithelium with cells modified by gene transfer. In the context of these properties of bronchial epithelium, adenovirus vectors have been evaluated for direct introduction of therapeutic genes to bronchial epithelium via the airway in vivo. An in vivo experiment revealed that gene transfer with a replication-deficient adenovirus containing the E. coli lacZ (beta-galactosidase) gene driven by cytomegalovirus promoter (AdCMVlacZ) was 10(4) times more efficient than gene transfer with a plasmid containing the same expression cassette (pCMVlacZ). An experiment based on in vitro data was done to evaluate the distribution of the expression of the exogenous genes transferred by adenovirus vectors. Intratracheal administration of AdCMVlacZ into lungs of experimental animals resulted in a high number of beta-gal-positive epithelial cells in bronchiols, rather than in proximal bronchi. Thus, a replication-deficient adenovirus can be used to transfer exogenous genes to airway epithelial cells in vivo. This technique may be useful in gene therapy for cystic fibrosis. Gene transfer can be thought of as the use of genetic information to modity the milieu of the target organ. In addition, gene transfer may allow the introduction of new genes, or the alteration tion of existing genes in intact animals. Gene transfer could them be used to produce animal models of human lung diseases that are particularly difficult to study.

Animals↗
PubMed1994

Successful bone marrow transplantation with rabbit anti-human thymocyte globulin in aplastic anemia. Report of a case previously treated with equine anti-human lymphocyte globulin.

Bone marrow transplantation is widely accepted as the first line therapy for patients with severe aplastic anemia. Patients with less severe forms of aplastic anemia are treated with immunosuppressive agents, hematopoietic growth factors or androgenic steroids. The use of rabbit anti-human thymocyte globulin allowed us to successfully transplant in a patient with a moderately severe form who once failed to respond to all conservative treatment including equine anti-human lymphocyte globulin. We propose that, given the availability of rabbit anti-human thymocyte globulin, marrow transplantation should be considered in non-severe aplastic anemia patients who are refractory to equine anti-human lymphocyte globulin.

Adult↗
PubMed1994

[Effect of calcitonin gene-related peptide and vasoactive intestinal polypeptide on delayed cerebral vasospasm studied after experimental subarachnoid hemorrhage in rabbits].

Calcitonin gene-related peptide (CGRP) and vasoactive intestinal polypeptide (VIP) are intrinsic vasodilatory substances contained in perivascular nerve fibers innervating large intracranial arteries. Effects of these substances on delayed cerebral vasospasm were examined using a rabbit model of experimental subarachnoid hemorrhage (SAH). Sixty-one anesthetized rabbits received intrathecal fresh arterial blood on day-1 and intrathecal administration of different doses of CGRP, VIP or distilled water on day-4. Prior to the treatment, caliber of the spastic basilar artery was 73.4 +/- 0.9% of pre-SAH values. Serial angiograms after treatment demonstrated that 10(-10)mol/kg of CGRP dilated the spastic artery to 117.1% of pre-SAH levels and that dilatory effect of CGRP continued up to 6 hours after treatment. VIP injection also brought arterial dilatation up to 114.9% of pre-SAH levels, although the duration of the effect was less than 3 hours. Intrathecal administration of CGRP or VIP showed no adverse effect on the systemic and neurological state of the animals. These results indicate that intrathecal CGRP and VIP have therapeutic potential in treating delayed cerebral vasospasm after subarachnoid hemorrhage. Further investigations are expected to extend the effect of CGRP and VIP.

Animals↗
PubMed1993

Sporogony of Theileria sergenti in the salivary glands of the tick vector Haemaphysalis longicornis.

Sporogony of Theileria sergenti in the salivary glands of the tick vector Haemaphysalis longicornis was observed by light and transmission electron microscopy. Fission bodies that developed from kinetes were observed as masses (approximately 32 x 15 microns) that occupied half of the acinous cell at 2 days after the infestation of ticks. Parasites possessed an irregular nucleus of low electron density, highly electron-dense granules, and mitochondrion-like bodies in the cytoplasm. Parasites developed into a multinucleate syncytium, increasing in size and complexity. Subsequently, the nuclei of parasites became round and highly electron-dense, and tubelike structures and rhoptries as precursors of the highly electron-dense granules appeared in the cytoplasm. Approximately 40,000 sporozoites arose via radial budding from the syncytium that had developed from kinetes. As in T. parva, no evidence of discrete secondary or tertiary sporoblasts was found in T. sergenti. The sporogony of T. sergenti was extremely similar to that of T. parva.

Animals↗
PubMed1993

Theileria sergenti infection in the Bo-RBC-SCID mouse model.

We have previously developed the Bo-RBC-SCID mouse model for Theileria sergenti infection. In the present study, this model was further examined to delineate the models of parasite infection. The Bo-RBC-SCID mice were prepared by periodically transfusing uninfected bovine erythrocytes (Bo-RBCs) into splenectomized SCID mice via the intraperitoneal (i.p.) route. The mice, separated into three groups, were inoculated i.p., intravenously (i.v.), or subcutaneously (s.c.) with T. sergenti-infected Bo-RBCs. Examination of samples of peripheral blood demonstrated that the parasite infected mice inoculated via any one of the three routes. The mice inoculated i.v., however, developed parasitemia earlier than those inoculated i.p. or s.c. When Bo-RBC-SCID mice prepared without splenectomy were infected with T. sergenti, a high-level parasitemia appeared only once. After that, not only the level of parasitemia but also the number of Bo-RBCs in the peripheral blood rapidly decreased despite the continuation of Bo-RBC transfusions. The results suggest that T. sergenti proliferates primarily in the circulating blood in Bo-RBC-SCID mice and that in response to the parasites growth, the spleen may play an important role in the removal of both parasitized and unparasitized Bo-RBCs from the blood circulation.

Animals↗
PubMed1993

The Bo-RBC-SCID mouse model for evaluating the efficacy of anti-theilerial drugs.

We have previously developed a mouse model which allowed the proliferation of Theileria sergenti in severe combined immunodeficiency (SCID) mice with circulating bovine erythrocytes (Bo-RBC). In the present study, this model was utilized to test the efficacy of anti-theilerial drugs. Bo-RBC-SCID mice were created by giving periodic transfusions of T. sergenti-free Bo-RBC, and subsequently infecting with T. sergenti. Three anti-protozoal compounds, Pamaquine (Yamanouchi Pharmaceutical Co. Ltd), Ganaseg (Japan CIBA-GEIGY Ltd) and Buparvaquone (Coopers Animal Health Ltd), were subcutaneously administered into the mice at doses recommended for cattle therapy. Blood examinations demonstrated that all three drugs significantly reduced the level of parasitemia although Ganaseg was effective only at a dose five times higher than that recommended for cattle therapy. Administration of the drugs neither caused any sign of acute toxicity nor changed the rate of Bo-RBC in the SCID mice's circulating blood cells. The results indicate that the Bo-RBC-SCID mouse model may offer a useful in vivo system for evaluating the efficacy of anti-protozoal drugs against T. sergenti.

Aminoquinolines↗
PubMed1993

Seroepidemiology of mycoplasmal pneumonia of swine in Japan as surveyed by an enzyme-linked immunosorbent assay.

Antibodies to Mycoplasma hyopneumoniae were surveyed by enzyme-linked immunosorbent assay (ELISA) on serum, colostrum and milk samples collected from sows and on sera of growing/finishing pigs in Japan. Only one of 196 specific-pathogen-free sows induced a low ELISA value, while 72% of 411 sows from conventional herds were seropositive. A seropositive rate in the conventional sows gradually decreased with an increase in farrowing frequency or with age. In 3267 growing/finishing pigs ranging in age from one to six months, a seropositive rate increased remarkably from the age of 4 months onwards, reaching the maximum at the age of 6 months. A survey conducted on 42 conventional farms revealed that the highest seroconversion occurred when pigs were 4 months of age. The level of maternal antibodies was proportional to that of the dam's colostral antibodies. After maternal antibodies waned, active immunity in newborn piglets from dams with high colostral antibodies appeared earlier and higher than that in piglets from dams with low colostral antibodies. In 950 slaughter pigs, there was a correlation between seropositiveness and the presence of pneumonic lesions, but the ELISA value did not correlate with the degree of the lesions. Pigs that were raised under unfavorable environmental conditions developed pneumonic lesions more frequently than pigs rearing under better conditions, regardless of their immune status. These results suggested that M. hyopneumoniae and some secondary respiratory pathogens may have been involved in the development of these pneumonias.

Age Factors↗