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Biomedical subjects

Y Tajima

Publications and source records attributed to Y Tajima.

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

Induction of extrahepatic biliary carcinoma by N-nitrosobis(2-oxopropyl)amine in hamsters given cholecystoduodenostomy with dissection of the common duct.

The methods we used to produce a carcinoma in the extrahepatic bile duct and gallbladder in hamsters are described along with the characteristics of the induced tumors. Female Syrian golden hamsters were first subjected to cholecystoduodenostomy with dissection of the extrahepatic bile duct on the distal end of the common duct (CDDB) and were, 4 weeks later, treated with weekly subcutaneous injections of N-nitrosobis(2-oxopropyl)amine (BOP) at a dose of 10 mg/kg body weight for 9 weeks. The animals were killed at the 12th, 16th and 20th week after the initiation of BOP treatment. Extrahepatic bile duct carcinoma developed in 16%, 24% and 41% and gallbladder carcinoma occurred in 58%, 81% and 82% of the hamsters, respectively, at the corresponding times of killing. The incidences were significantly higher than those in sham-operated controls (P < 0.01). The induced extrahepatic bile duct carcinomas were predominantly of the polypoid type and gallbladder carcinomas were of the papillary type in growth form, being morphologically similar to early stage biliary carcinoma in humans. Immunohistochemical staining using bromodeoxyuridine and anti-bromodeoxyuridine monoclonal antibody demonstrated that the CDDB procedure greatly accelerated the cell kinetic activity of the biliary epithelium, and this was considered to be a major factor promoting the development of biliary carcinomas in this hamster model. In conclusion, this new model provides a high incidence of tumor development at the extrahepatic biliary tract and is expected to be useful for clarifying the characteristics of this highly malignant tumor.

Animals↗
PubMed1994

MR appearance of subacute combined degeneration of the spinal cord.

Subacute combined degeneration (SCD) of the spinal cord is well known to produce degenerative lesions in the spinal cord histopathologically, but a few reports on the neuroradiological findings have so far been reported. We presented the MRI findings of the spinal cord in a case of SCD. The localization of the radiologically proven lesions was similar to that of the previous pathological reports.

Aged↗
PubMed1994

Photoreceptor differentiation of retinoblastoma: an electron microscopic study of 29 retinoblastomas.

Retinoblastomas exhibit a unique form of differentiation to produce cell elements similar to those seen in a photoreceptor cell. An ultrastructural study was performed on 29 cases of retinoblastoma to further clarify the cytologic characteristics of the tumor cells. The age of the retinoblastomas averaged 17.1 months and the tumor cells showing photoreceptor differentiation were demonstrated in 10 cases (35%). The findings were especially notable in retinoblastomas with Flexner-Wintersteiner rosette formation (seven cases, 28%). Similar photoreceptor differentiation was also evident in solid cell clusters without rosette formation (four cases, 14%). The presence of photoreceptor elements was assumed to be significantly frequent both in Flexner-Wintersteiner rosettes and in the solid cell clusters. The cell cytoplasm also showed proliferation of long mitochondria and microtubules, reflecting photoreceptor differentiation. The hereditary-type retinoblastoma showed more advanced cell differentiation than the non-hereditary type. Photoreceptor differentiated retinoblastoma showed rather indolent growth compared with the undifferentiated type, and the former can expect a curative treatment by operation. These observations provide additional findings of the biological nature of retinoblastomas.

Cell Differentiation↗
PubMed1994

Switching of mouse spermatogonial proliferation from the c-kit receptor-independent type to the receptor-dependent type during differentiation.

Testicular cells composed mostly of germ cells and immature Sertoli cells from neonatal mice 2 and 5 days old were cultured to investigate germ-cell proliferation mediated by the c-kit receptor. The addition of antibody to block the interaction of the c-kit receptor with its ligand inhibited the proliferation of cultured spermatogonia from 5-day-old mice in a dose-dependent manner, but not from that of 2-day-old mice. The addition of anti-c-kit ACK2 monoclonal antibody also inhibited the proliferation of spermatogonia from 5-day-old mutant Sld/Sld mice but not of 5-day-old mutant Wv/Wv mice. The results indicate that c-kit-positive type A spermatogonia in the testes of 5-day-old mice require steel factor (kit ligand) for their proliferation, whereas self-renewal and differentiation of c-kit-negative primitive type A spermatogonia in the testes of 2-day-old mice do not.

Animals↗
PubMed1994

Clinico-radiological findings of neuro-Behçet's syndrome.

We examined 21 cases of Neuro-Behçet's syndrome in detail, and present here their clinicoradiological characteristics. Clinically, signs of pyramidal tract and meningeal irritation were frequently observed. In contrast to previous reports, our study demonstrated a near equal frequency in the occurrence of focal cerebral lesions and that of focal brain stem lesions. Notably, our results showed that the atrophy of both the cerebrum and the brain stem was often observed, indicating the presence of continuous disease activity in the central nervous system (CNS). In accordance with the high frequency of meningeal irritation signs, all of our cases exhibited pleocytosis in the cerebrospinal fluid (CSF). These results indicated the possibility that chemical mediators secreted from infiltrating cells in the CSF may somehow inflict damage to the CNS in Neuro-Behçet's syndrome.

Adult↗
PubMed1994

Sequential magnetic resonance features of encephalopathy induced by systemic mastocytosis.

A 37-year-old man developed encephalopathy with prominent eosinophilia. Magnetic resonance imaging (MRI) revealed multiple T2-weighted high signal intensity lesions with dimeglumine gadopentetate (Gd-DTPA) enhancement on T1-weighted images, which were distributed in the cerebral cortex, thalamus, deep white matter and cerebellum. He was diagnosed as having systemic mastocytosis on the basis of proliferating mast cells in the bone marrow and peripheral eosinophilia. Following steroid administration, there was a rapid improvement of his symptoms and laboratory data. To our knowledge, this was the first reported case of systemic mastocytosis provoking encephalopathy with serial MRI findings.

Adult↗
PubMed1994

Temporal alterations of immunohistochemical findings in polymyositis.

To investigate the pathological mechanisms of polymyositis, we performed immunohistochemical analyses with biopsied muscles. Comparative studies using specimens obtained from the same patient enabled us to analyze the pathological alterations at different sequential clinical phases without taking into account each immunogenetic difference. Expression of MHC (major histocompatibility complex) antigens, especially ectopic MHC-class-II antigens, in muscle fibers and infiltrating T-cells were shown to increase concomitantly with the clinically observed exacerbation. Moreover, other observations seem to support the possibilities that 1) administration of steroids lowers the number of invading CD8-positive cells, 2) induction of MHC-class-I antigens in muscle fibers precedes the inflammatory cell infiltration and that 3) remaining MHC-class-I antigens in muscle fibers may explain the recurrence of myositis often observed in the follow up period.

Adrenal Cortex Hormones↗
PubMed1994

[Why should we measure MIC?].

In actual infectious diseases, bacterial invasion and the effect of antibiotics show "dynamic" behavior, being continuously influenced by various factors. Therefore, "some" knowledge and experience are essential to treat a patient and to make an appropriate decision through only limited information. On the other hand, many patients today still die of infection at the terminal state of illness. Therefore, the importance of "clinical microbiology" has not faded away at all, and will increase much more in the future. However, medical students are not well taught "drug-dynamics" and "how to perform empiric therapy" in the under-graduate curriculum. Thus, such knowledge must be obtained by "self-effort"; i.e., why MIC should be measured, how to make use of MIC for treatment, what the most important information upon treatment of infection is, what moiety is not reflected by MIC, how to judge from which point of MICs, and so on. Furthermore, education or guidance in such fields are not always provided even in the post-graduate training course. To solve these difficulties, we originated a new computer system supporting antimicrobial chemotherapy, which has actually been working well in our hospital from May of 1994. This system is intended to convey maximally the "meaning" of the test results, instead of just reporting only "prosaic" results. In this system, detailed information on various kinds of bacteria and antibiotics is immediately available on every computer monitor. Furthermore, the data base on the average concentration of various antibiotics expected to be reached in each organ by every dose method is already in the system. When MIC actually measured is larger or smaller than such a value, a signal of "untreatable" or "treatable" will appear on the monitor. This is an epoch-making system in Japan, and will help the physicians to provide effective therapy.

Bacterial Infections↗
PubMed1994

Tap needle for laparoscopic surgery: a safe and easy technique for holding tissues.

To achieve and maintain a wide operative field during laparoscopic surgery, we developed a "tap needle" that can penetrate the skin into the peritoneal or pleural cavities and can be used to pick up threads introduced into the cavities to elevate tissues or organs. The characteristics of the tap needle and method of use are reported herein.

Abdomen↗
PubMed1993

Simple, rapid and simultaneous measurement of eight different types of carbamate pesticides in serum using liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

We have developed a method for simultaneous analysis of methylcarbamate pesticides in serum with an acute pesticide intoxication. This is performed by liquid chromatography-atmospheric pressure chemical ionization mass spectrometry. Rapid detection of eight types of methylcarbamate pesticide can be achieved with this method, it only requires an extremely simple pre-treatment of the sample. The specificity of this method is equal to that of gas chromatography-mass spectrometry, and it satisfies the clinical requirements for detection sensitivity and specificity. Although some problems with this analytical method remain to be solved, we consider it to be superior to any other analytical method previously reported.

Acetates↗
PubMed1993

Intrahepatic cholangiocarcinoma with sarcomatous change. Clinicopathologic and immunohistochemical evaluation of seven cases.

BACKGROUND: Although there have been a few reports dealing with the sarcomatous changes of intrahepatic cholangiocarcinoma, its clinicopathologic features as well as immunohistochemical nature remain obscure. METHODS: Among 155 cases of intrahepatic cholangiocarcinoma, 7 cases of sarcomatous cholangiocarcinoma were chosen. Immunohistochemical studies using the avidin-biotin-peroxidase complex method were performed on these cases. RESULTS: The tumor showed both mucin-producing adenocarcinoma areas and sarcomatous areas, the latter being predominant in three cases and focal in the other four. All the sarcomatous areas consisted of atypical spindle cells arranged in sheets or bundles. Pleomorphic giant cells were observed in some sarcomatous components in five cases. Immunohistochemical staining for keratin and epithelial membrane antigen revealed apparent positivity in the sarcomatous components of five cases. The patients with these tumors showed aggressive intrahepatic spreading and widespread metastasis of the sarcomatous cells, and demonstrated poorer prognosis than those with ordinary cholangiocarcinoma, with one exception, a patient who remained disease-free for 3 years after surgery. CONCLUSIONS: These findings favor the possible epithelial origin of sarcomatous cells. Radical operation would be necessary for patients with this special type of cholangiocarcinoma.

Adenocarcinoma, Mucinous↗
PubMed1993

Establishment of a transplantable carcinoma arising from the intrahepatic bile duct in Syrian golden hamsters.

A subcutaneously transplantable cancer line from the intrahepatic bile duct (IHBD) induced by N-nitrosobis(2-oxopropyl) amine was established in Syrian golden hamsters. The doubling time of this tumour was 2.6 days when 2 x 10(5) tumour cells were inoculated subcutaneously (take-up rate was 100%). Growth of the tumour was significantly faster in male hamsters but neither oestrogen nor androgen receptors were detected in the tumour. The primary and all allograft tumours were tubular adenocarcinomas with fibrosis and a scirrhous pattern resembling human IHBD carcinoma of the peripheral type. Transmission electron microscopic findings showed irregular glands covered with numerous microvilli. Blood-group-related antigens including A, B and H were positive. P-Glycoprotein, which is an indicator of multidrug resistance, was also positive. Carcinoembryonic antigen and CA19-9 as general tumour markers of the biliary tract were negative. The deoxyribonucleic acid (DNA) pattern of this transplantable carcinoma was diploid. This newly established animal model of a transplantable IHBD carcinoma can be used to examine the mechanisms of synthesis and secretion of tumour-associated antigens and to study potential therapeutic agents.

Adenocarcinoma↗
PubMed1993

Partial cloning of the rat choline acetyltransferase gene and in situ localization of its transcripts in the cell body of cholinergic neurons in the brain stem and spinal cord.

We have isolated recombinant lambda (lambda) phages which contain a part of the rat choline acetyltransferase (ChAT) gene. Restriction and Southern blot analyses using synthetic oligonucleotides indicate that these clones overlap one another and contain at least four exons which reside in 16.4 kb of sequence encoding from the middle to the 3' end, but not the 5'-region, of the rat ChAT gene. Partial sequence analyses revealed that the clones contain an exon whose nucleotide sequence corresponds to a highly conserved region of ChAT during evolution. RNase protection mapping experiments show that sequences represented by this exon are expressed at high levels in the spinal cord of adult rats and at low but detectable levels in PC12 cells. By using the genomic sequences, including the exon, as a hybridization probe, we have detected ChAT mRNAs in situ in rat tissues. In situ hybridization experiments using radioactive and non-radioactive probes revealed that cholinergic motoneurons in the spinal cord, the laterodorsal tegmental nucleus as well as the hypoglossal nucleus in the brain stem were labeled, suggesting that the genomic sequence can be used as a probe to measure the ChAT mRNA levels in those cholinergic neurons. The results also indicate that the non-radioactive method gives a better resolution in localizing the expression of ChAT transcripts in the cytoplasm of cholinergic neurons.

Amino Acid Sequence↗
PubMed1993

Epidermoid carcinoma originating from the gingival sulcus.

This paper describes a case of epidermoid carcinoma originating from the gingival sulcular epithelium with proper plane of histopathology. Relevant articles on carcinoma of gingiva are briefly reviewed, and the necessity for early diagnosis of this lesion is emphasised.

Aged↗
PubMed1993

Efficient production of recombinant human factor VIII by co-expression of the heavy and light chains.

We have developed a high-level expression system for human blood coagulation factor VIII (FVIII) consisting of a 90 kDa heavy (H-)chain and an 80 kDa light (L-)chain. Two expression plasmids were prepared, one expressing the H-chain and the other expressing the L-chain. These recombinant plasmids were designed to produce each chain linked to short additional amino acid residues derived from the FVIII precursor sequence. Furthermore, Kozak's translation initiation consensus sequence was introduced into the start codon for the H-chain. These modifications have dramatically increased the levels of expression of these chains. Chinese hamster ovary (CHO) cells co-transfected with these two recombinant plasmids were subjected to gene amplification and cloning. The final cell line, designated CTC-CF8, secretes 15 IU/day/10(6) cells of active FVIII which is indistinguishable from plasma-derived FVIII in its structure and biochemical properties. This system is suitable for large-scale production of pathogen-free recombinant human FVIII which can be used for the treatment of haemophilia A patients.

Amino Acid Sequence↗
PubMed1993

A factor found in aged tungstate solution enhanced the antibacterial effect of beta-lactams on methicillin-resistant Staphylococcus aureus.

We have found a factor (Factor T) in aged mixtures of tungstate and phosphate which greatly enhances the antibacterial effects of beta-lactams on both inducible and constitutive methicillin-resistant Staphylococcus aureus, but not on methicillin-susceptible S. aureus. Factor T alone did not strongly inhibit bacterial growth. There was no synergism of Factor T with other classes of antibiotics, nor with other groups of bacteria, and it reduced the efficacy of amino-glycosides and tetracycline. Upon preparation of Factor T, acidifying and heating the mixture of tungstate and phosphate resulted in a high yield and reproducibility, and no enhancing effect was observed when other anions such as sulfate or molybdate were used instead. Factor T is heat- and acid-stable but labile to alkalization, and is probably a complex of phosphate and tungstate.

Anti-Bacterial Agents↗
PubMed1993

Hot water epilepsy with pineal cyst and cavum septi pellucidi.

A case of reflex epilepsy accompanied by pineal cyst and cavum septi pellucidi induced by hot water bathing is presented. The patient is a 25-year-old male who has had six episodes of convulsions during the last three years. The seizures were diagnosed as a complex partial epilepsy followed by generalized tonic seizures. We have succeeded in recording his electroencephalogram (EEG) during convulsions. Moreover, a magnetic resonance imaging (MRI) study revealed a pineal cyst and cavum septi pellucidi. This is quite a rare form of adult hot water epilepsy accompanied by intracranial malformations.

Adult↗