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Biomedical subjects

T Nagata

Publications and source records attributed to T Nagata.

At least 595 records · Page 33Linked to original sources
PubMed1981

N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide, a calmodulin antagonist, inhibits cell proliferation.

N-(6-Aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) and its derivatives are putative calmodulin antagonists that bind to calmodulin and inhibit Ca2+/calmodulin-regulated enzyme activities. Autoradiographic studies using tritiated W-7 showed that this compound penetrates the cell membrane, is distributed mainly in the cytoplasm, and inhibits proliferation of Chinese hamster ovary K1 (CHO-K1) cells. Cytoplasmic [3H]W-7 was excluded completely within 6 hr after removal of [3H]W-7 from the culture medium. N-(6-aminohexyl)-1-naphthalenesulfonamide, an analogue of W-7 that interacts only weakly with calmodulin, proved to be a much weaker inhibitor of cell proliferation. CHO-K1 cells were synchronized by shaking during mitosis and then released into the cell cycle in the presence of 25 microM W-7 or 2.5 mM thymidine for 12 hr. Cell division was observed approximately 6 hr later. The results suggest that the effect of W-7 on cell proliferation might be through selective inhibition of the G1/S boundary phase, which is similar to the effect of excess thymidine. This pharmacological demonstration that cytoplasmic calmodulin is involved in cell proliferation is significant; W-7 and its derivatives may be useful tools for research on calmodulin and cell biology-related studies.

Animals↗
PubMed1980

A radioautographic study on the incorporation of 14C-bupranolol (beta-blocking agent) into the rabbit eye.

Localization of instilled 14C-bupranolol was studied in the rabbit eye by means of light microscopic radioautography. After the administration of 50 microliter of 14C-bupranolol into the eyes of two rabbits, both eyes were enucleated at intervals of 15 and 30 min respectively, and radioautographic procedures were carried out on cryostat sections by means of both dry-mounting and wet-mounting methods. Although with the former it was possible to demonstrate many radioautographic silver grains in the specimens, with the latter it was not possible to detect their localization. On the dry-mounting procedure, radioautographic grains were observed mainly in the epithelium of the ciliary body 15 and 30 min after the administration of 14C-bupranolol. The numbers of grains were counted on the 15 and 30 min specimens. They were decreased in the conjunctiva, and cornea 30 min after the administration. On the contrary, they were remarkably increased in the epithelium of the ciliary body. From these results it is concluded that the 14C-bupranolol first penetrates into the epithelium of the conjunctiva and cornea, then moves rapidly to the ciliary body, and that only very small amount of 14C-bupranolol is changed into the insoluble form. Also, these results suggest that bupranolol plays a role in the control of aqueous production in the ciliary processes.

Animals↗
PubMed1980

Absence of tectotectal pathway in the rabbit: an anatomical and electrophysiological study.

Absence of tectotectal pathway in rabbits is demonstrated by means of anatomical (retrograde axonal transport of horseradish peroxidase (HRP)) and of physiological (electrical stimulation of the superior colliculus (SC)) methods. Despite the absence of that pathway it was still possible to verify the occurrence of electrophysiological correlates of Sprague's phenomenon. It is suggested that, in rabbits at least, reciprocal inhibitory influences between the colliculi can be mediated by pathway(s) other than the tectotectal projection. It is also hypothesized that the absence of tectotectal pathway could possibly be functionally correlated to a small degree of binocular vision and to a small representation of the ipsilateral visual hemifield in the superior colliculus.

Animals↗
PubMed1980

Isolation and characterization of Escherichia coli dnaA amber mutants.

Specialized transducing phage lambda (formula, see text) dnaA-2 was mutagenized, and two derivatives designated lambda (formula) dnaA17(Am) and lambda (formula) dnaA452(Am) were obtained. They did not transduce such mutations as dnaA46, dnaA167, and dnaA5 when an amber suppressor was absent, but they did so in the presence of an amber suppressor. By contrast, they transduced the dna-806 and tna-2 mutations in the absence of an active amber suppressor. The dna-806 and tna-2 mutations are known to be located very close to the dnaA gene, but in separate cistrons. When ultraviolet light-irradiated uvrB cells were infected with the derivative phages and proteins specified by them were analyzed by gel electrophoresis, a 50,000-dalton protein was found to be specifically missing if an amber suppressor was absent. This protein was synthesized when an amber suppressor was present. The dnaA17(Am) mutation on the transducing phage genome was then transferred by genetic recombination onto the chromosome of an Escherichia coli strain carrying a temperature-sensitive amber suppressor supF6(Ts), yielding a strain which was temperature sensitive for growth and deoxyribonucleic acid replication. The temperature-sensitive trait was suppressed by supD, supE, or supF. We conclude that, most likely, the derivative phages acquired amber mutations in the dnaA gene whose product is a 50,000-dalton protein as identified by gel electrophoretic analysis.

Bacterial Proteins↗
PubMed1980

Netherton's syndrome which responded to photochemotherapy.

We are reporting on a 22-year-old female patient with typical Netherton's syndrome who responded to photochemotherapy with the application of 8-MOP solution and irradiation with UVA. After two or three courses of PUVA therapy, each requiring 1 week, the skin condition improved. Maintenance photochemotherapy was necessary. Because there was a similarity between psoriasis and our case in the histological findings, this modality may be justified. No side effects were observed.

Adult↗
PubMed1980

Phlebitis associated with the intravenous use of cephapirin and cephalothin in the combination therapy of antibiotics.

Phlebitis related to antibiotic infusion is one of the most frequent causes of morbidity in the debilitated patients with severe infection. There are a number of causes of infusion-induced phlebitis such as pH of intravenous fluid, needle used, and contamination of venipuncture site. Vein used to play an important role, particularly in patients with granulocytopenia receiving intravenous infusion. Cephalothin is an effective antibiotic in the treatment of granulocytopenic infection and is widely used currently. When cephalothin was introduced commercially, the frequency of phlebitis was as high as 50%. The main reason was thought to be acidity of the antibiotic solution. The cephalothin solution used currently is neutral in pH, but prevention of phlebitis is still not perfect. In contrast, cephapirin recently developed cephalosporin antibiotic, which resembles cephalothin in the antimicrobial activity and pharmacological properties caused less phlebitis than cephalothin in initial clinical studies. The patients receiving chemotherapy for malignant diseases frequently die of infections. A cephalosporin antibiotic is administered intravenously for a prolonged time in the presence of thrombocytopenia, and under such circumstances, other antibiotics such as carbenicillin (CBPC) and aminoglycoside are usually used in combination. The influence of these antibiotics injected through the same vein must be considered, but the possibility of phlebitis due to CBPC and aminoglycoside is negligible. In the present clinical study, 24 granulocytopenic patients were treated with the combination of antibiotics, cephapirin-carbenicillin-amikacin and cephalothin-carbenicillin-amikacin. Besides the clinical effect of the antibiotics, the incidence and severity of phlebitis were studied.

Agranulocytosis↗
PubMed1979

Tactile neurons of the superior colliculus of the cat: input and physiological properties.

Neurons in the strata intermediale and profundum of the cat superior colliculus (SC) previously have been shown to be organized somatotopically and to respond to tactile stimuli. The stimulus properties required for neuronal activation suggest that these neurons are excited by inputs from selected classes of high-velocity, sensitive cutaneous mechanoreceptors, and that stimulus-response relationships indicate only a narrow range of information concerning stimulus magnitude. The properties of these neurons have been interpreted as serving a role in stimulus detection that recovers slowly and may be best suited for directed attention and orientation behavior. The input to the SC was studied by injection of horseradish peroxidase (HRP) for retrograde labeling of neurons projecting to this region. The main inputs subserving the tactile pathway are the principal trigeminal nucleus and the rostral portion of the spinal V subnucleus oralis and the main cuneate nucleus. Sparser labeling was found in other somatic relays, including the gracile and lateral cervical nuclei and posterior portion of the spinal trigeminal complex. Several other projections relating to visual mechanisms are also described.

Animals↗
PubMed1979

Mucosubstances of rabbit granulocytes studied by means of electron-microscopic radioautography and X-ray microanalysis.

Rabbit bone marrow cells have been studied by means of light- and electron-microscopic radioautography and X-ray microanalysis. Carrier free sulfuric acid was used as the radioactive precursor in this experiment. Immature granulocytes showed more active incorporation than mature ones. Silver grains were observed in the Golgi apparatus and granules in three kinds of granulocytes. Electron-microscopically, immature granules showed the incorporation of inorganic sulfate, while mature ones did not. Sulfur was detected in all kinds of granules of the three granulocyte types by X-ray microanalysis. It is concluded that incorporated inorganic sulfur may be utilized for the synthesis of acid glycosaminoglycans and the sulfur detected by X-ray microanalysis may be that contained in the acid glycosaminoglycan. The sulfur detected in the specific granules of the heterophil probably derives from proteins or polypeptides incorporating sulfur containing amino acids.

Animals↗
PubMed1979

A recent trend of drug dependence in Kurume district (southern Japan).

With the intention of grasping the trend of drug dependence in recent years, a comparative study was made of the relative prevalence of three different types of drug dependence, i.e., the sociopathic, neurotic and iatrogenic types, in each of the three postwar decades among patients seen at the neuropsychiatric clinic of Kurume University. As a result it was found that the recent trend of drug dependence has the following features: (1) multiplicity of drugs involved, (2) a continuing high incidence of the iatrogenic types, (3) resurgence of the sociopathic type, making the recent pattern of drug dependence similar to that prevailing in postwar years, and (4) prevalence of dependence or abuse among the younger generation. Consideration was also given to the sociopathologic significance of these recent features of drug dependence.

Age Factors↗
PubMed1979

Cloning and physical mapping of the dnaA region of the Escherichia coli chromosome.

The dnaA gene of Escherichia coli K-12, supposedly present in the deoxyribonucleic acid (DNA) of specialized transducing phase lambda i21 dnaA-2, was cloned onto plasmid pBR322. The new plasmid was named pMCR501. Physical analyses of DNAs of lambda i21 dnaA-2 and pMCR501 revealed the following. The lambda i21 dnaA-2 DNA retained the delta sr I lambda 1-2 and ninR5 deletions and imm21 substitution which were originally present in the parental phage. The size reduction was compensated for by the insertion-substitution segment (tna-dnaA region) in lambda i21 dnaA-2 DNA. The fractional size of this segment was approximately 7 megadaltons (Md), or 10 kilobases, which was found to be the sum of the tna insertion subsegment of ca. 3.5 Md and the dnaA substitution subsegment of ca. 3.5 Md. Phage P1-mediated transductional mapping between the dnaA46 and tna mutations gave a cotransduction frequency of 84%, corresponding to approximately 5 kilobases. Thus, it is strongly suggested that the dnaA gene resides in the lambda i21 dnaA-2 DNA. Cleavage mapping with the restriction endonuclease of pMCR501 DNA confirmed that it was constructed by excising a BamHI fragment of 4.29 Md, containing the 3.5-Md dnaA substitution segment, from the lambda i21 dnaA-2 DNA, inserting it into the sole BamHI cleavage site on pBR322.

Bacteriophage lambda↗
PubMed1979

Conditionally lethal amber mutations in the dnaA region of the Escherichia coli chromosome that affect chromosome replication.

Three amber mutations, dna-801, dna-803, and dna-806, were isolated by localized mutagenesis of the dnaA-oriC region of the chromosome from an Escherichia coli strain carrying temperature-sensitive amber suppressors. When the mutations were not suppressed at 42 degrees C, the cells did not grow and DNA synthesis was arrested. They were very closely linked to each other and to the dnaA46 mutation. The mutant phenotype of each strain was converted to the wild type by infecting the mutants with specialized transducing phase lambda i21 dnaA-2 but not with lambda i21 tna. Derivatives of lambda i21 dnaA-2, each of which carried the amber mutation dna-801 dna-803, or dna-806, converted the dnaA mutant phenotype to Dna+ but did not convert rhe amber mutants to the wild-type phenotype. E. coli uvrB cells were irradiated with ultraviolet light and infected with each of these phage strains. An analysis of proteins synthesized in the cells revealed that two proteins with molecular weights of 50,000 and 43,000 were specified by lambda i21 dnaA-2 but not by lambda i21 tna. When the ultraviolet-irradiated cells did not carry an amber suppressor, the derivative phage with the amber mutation invariably failed to produce the 43,000-dalton protein, but when the host cell carried supF (tyrT), the protein was produced. The 50,000-dalton protein was unaffected.

Bacterial Proteins↗