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M Azuma

Publications and source records attributed to M Azuma.

At least 397 records · Page 22Linked to original sources
PubMed1985

Response properties of prefrontal visual neurons in the awake monkeys.

Response properties of the visual neurons in the prearcuate and periprincipal areas of the prefrontal cortex were examined in awake monkeys. The findings obtained are as follows: (1) Most of the visual neurons responded with various excitatory fashions to a light spot presented in their visual receptive fields (RFs). The response was large when the stimulus was applied to the middle of the RF and became smaller when the stimulus position was moved from this part toward the RF border. (2) The response was affected by the size of the stimulus. The largest response was usually obtained by a small stimulus. The shape, orientation, brightness of the stimulus and the direction of its movement gave little influence on the response strength and pattern. (3) In about a half of the neurons the response was enhanced when the monkey made a saccadic eye-movement toward a visual stimulus in the RF. (4) Some of the above-mentioned response properties were quantitatively different from one another among neuron groups classified according to the eccentricity and size of their RFs. These results suggest that the properties of the neurons are suitable for detecting a visual stimulus occupying a limited extent in the space.

Animals↗
PubMed1985

Intermediate-sized filaments and specific markers in a human salivary gland adenocarcinoma cell line and its nude mouse tumors.

The adenocarcinoma cell line HSG from human salivary gland, which proliferates in vitro or in nude mice, was examined by the immunoperoxidase method for the expression of three different types of intermediate-sized filaments (IFs) and of specific antigens such as carcinoembryonic antigen, S-100 protein, secretory component, lactoferrin, myosin, tropomyosin, and actin. The cultured HSG cells were found to express three different types of IFs defined by antibodies to keratin, vimentin, and desmin. In HSG cells proliferating in vitro at 34 degrees C and 37 degrees C but not at 39 degrees C, the expression of tropomyosin and carcinoembryonic antigen was observed, although myosin and S-100 protein were not detected. The expressions of actin, lactoferrin, and secretory component were restricted to cultured HSG cells at 39 degrees C and 37 degrees C, respectively. Transplantation of HSG cells into nude mice resulted in the establishment of a nude mouse system with malignant characteristics such as invasion and metastasis. The expression of IFs in the primary tumors was restricted to keratin and desmin IFs, whereas coexpression of keratin, vimentin, and desmin IFs was observed in some neoplastic cells present in the metastatic tumors in regional lymph nodes and lung. In addition, expression of actin, myosin, tropomyosin, and S-100 protein was found in the metastatic tumors, whereas myosin and S-100 protein were not detected in the primary tumors. Moreover, the metastatic tumors were almost occupied by the neoplastic cells with oncocytic changes, although oncocytic change was not found in the cultured HSG cells and their primary tumors.

Adenocarcinoma↗
PubMed1985

Transforming genes in human leukemia cells.

High-molecular weight DNAs of fresh bone marrow cells from 32 patients with fresh leukemia were assayed for the presence of transmissible activated transforming genes by a DNA-mediated gene transfer technique using NIH/3T3 cells. DNAs of bone marrow cells from four of the 32 patients induced transformation of NIH/3T3 cells. Two of the four cases, a chronic myelogenous leukemia and an acute lymphocytic leukemia, contained activated N-ras oncogenes. Molecular cloning and nucleotide sequence analysis revealed that the lesion responsible for the transforming activity was localized to a single nucleotide transition from guanine to thymine in codon 12 of the predicted protein in each of the two cases. These observations indicate that activation of N-ras oncogenes is independent of the specific stage of cell differentiation or the leukemia phenotype. The other two transforming genes associated with an acute myelogenous leukemia and an acute lymphocytic leukemia showed homology neither with members of the ras gene family nor with the human Blym-1 gene. Thus, the NIH/3T3 transfection assay frequently detects activated N-ras oncogenes in human leukemias, while other transforming genes, distinct from the ras gene family, can be detected in some leukemias by the transfection assay.

Autoradiography↗
PubMed1985

Expression of epidermal growth factor and transforming growth factor-beta in human salivary gland adenocarcinoma cell line.

Neoplastic intercalated duct cells that originated from a human submandibular salivary gland release transforming growth factor and human epidermal growth factor into serum-free medium. The transforming growth factor with the soft agar colony-forming activity when assayed in the presence of mouse epidermal growth factor on normal rat kidney clone 49F indicator cells, but without mitogenic action to quiescent 3T3 cells, does not compete with epidermal growth factor for receptor binding, is heat and acid resistant but trypsin and dithiothreitol sensitive, and therefore is of the transforming growth factor-beta class. The immunoreactive human epidermal growth factor is detected by radioimmunoassay on certain fractions obtained by the Bio-Gel P-60 chromatography of neoplastic epithelial duct cells originated from a human submandibular salivary gland-conditioned medium and is biologically very similar to mouse epidermal growth factor. Moreover, the presence of human epidermal growth factor in cultured neoplastic epithelial duct cells originated from a human submandibular salivary gland is demonstrated by the peroxidase:antiperoxidase method.

Adenocarcinoma↗
PubMed1985

Electrophysiologic effects of enflurane and halothane on isolated rabbit hearts in the presence and absence of metabolic acidosis.

Electrophysiologic effects of halothane and enflurane in the presence of a normal pH and during metabolic acidosis were examined in isolated rabbit hearts perfused at a constant rate. During exposure to a normal pH, both halothane and enflurane produced concentration-dependent suppression of sinus node automaticity and atrioventricular conduction. Intraatrial and intraventricular conduction times during constant pacing were slightly but significantly prolonged by these anesthetics at 2 MAC. The magnitudes of these electrophysiologic changes were similar with halothane and enflurane when compared at the same MAC. These electrophysiologic effects became more marked during metabolic acidosis (pH 6.9). These results suggest that enflurane and halothane have direct depressant actions on the cardiac conduction system and that these electrophysiologic effects may be augmented by metabolic acidosis.

Acidosis↗
PubMed1984

Amyloid vascular disease and contracted kidneys--report of a case with review of literature.

A case of systemic amyloidosis associated with bronchiectasis is presented. At necropsy, contracted kidneys and centrilobular necrosis of the liver were observed. Systemic blood vessels had heavy deposition of amyloid, and the possibility of visceral ischemia and the development of contracted kidneys due to amyloid vascular disease as a pathogenetic relationship, was discussed against the background of a review of the literature.

Aged↗
PubMed1984

Properties and distribution of auditory neurons in the dorsolateral prefrontal cortex of the alert monkey.

In alert monkeys, some prefrontal neurons located in the superior dorsolateral area were activated to acoustic stimuli delivered in a restricted range of directions with respect to the animal's head. The effective direction was usually contralateral to the animal. The function of the auditory neurons in connection to that of the visual ones, which are commonly found in the prefrontal cortex, is discussed.

Acoustic Stimulation↗
PubMed1984

Effect of N-acetyl-muramyl-L-alanyl-D-isoglutamine on interferon production in mice by Newcastle disease virus.

The activity (carbon clearance) of the reticuloendothelial system (RES) of mice inoculated intraperitoneally with N-acetyl-muramyl-L-alanyl-D-isoglutamine (muramyl dipeptide, MDP) was greatly stimulated 1 day, but not 7 days after MDP treatment. No enhancement of resistance to ectromelia virus infection and influenza virus infection in mice treated with MDP was observed. In mice splenectomized 1 week after MDP pretreatment, normal levels of circulating interferon were produced in response to Newcastle disease virus (NDV), whereas in the mice treated with MDP after splenectomy, circulating interferon levels were reduced to the same level as produced in the MDP-untreated and splenectomized mice. Interferon production in response to NDV was augmented in non-adherent peritoneal and spleen cell cultures derived from MDP-pretreated mice, whereas it was reduced in peritoneal and splenic macrophage cultures. These results suggest that the non-adherent spleen cells activated with MDP were disseminated from the spleen to other organs, that the lack of enhancement of interferon production in mice pretreated with MDP might be due to reduced interferon production in macrophages, and that the activation of the RES of the whole body by MDP did not correlate with the enhancement of interferon production in spleen cells or with the reduction of interferon production in macrophages.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1983

Topographic studies on visual neurons in the dorsolateral prefrontal cortex of the monkey.

The topographic distribution and organization of visual neurons in the prefrontal cortex was examined in alert monkeys. The animal was trained to fixate straight ahead onto a tinty, dim light spot. While he was fixating, we presented a stationary second light spot (RF spot) at various locations in the visual field and examined unit responses of the prefrontal neurons to the RF-spot stimulus. Many prefrontal neurons, especially those located in the relatively superficial layers of the cortex, responded with a phasic and/or tonic activation to the RF spot illuminating a limited extent of the visual field, a receptive field (RF) being so determined. The visual neurons were found to be widely distributed in the prearcuate and inferior dorsolateral areas. One hemisphere mainly represented the contralateral visual field. According to the location of the neurons in these areas, their visual properties varied with respect to RF eccentricity from the fovea and in size. The neurons located in the lateral part of the areas and close to the inferior arcuate sulcus had relatively small RFs representing the foveal and parafoveal regions. When the recording site was moved medially, the RFs became eccentric from the fovea and were larger. Then, the neurons located between the caudal end of the principal sulcus and the arcuate sulcus had RFs with a considerable eccentricity. The size of the RF became progressively larger for anteriorly located neurons and this occurred generally without a change in RF eccentricity. The visual neurons were not organized on a regular pattern in the cortex with regard to their RF direction (vector angle) from the foveal region. From these observations, we conclude, first, that the prearcuate and inferior dorsolateral areas of the prefrontal cortex are functionally differentiated so that the lateral area's function is related to central vision, while that of the medial area to ambient vision. Second, the RF representation on the cortex with loss of the vector relation may generate an interaction between separate objects in visual space and may subserve the control of attention performance.

Animals↗
PubMed1983

Mechanisms of enhanced resistance of Mycobacterium bovis BCG-treated mice to ectromelia virus infection.

The mechanism of enhanced resistance of Mycobacterium bovis BCG-treated mice to ectromelia virus infection was investigated by determining the effect of splenectomy, antithymocyte serum, and antimacrophage serum on resistance. It was greatly reduced by these treatments, not only in normal mice, but also in mice treated with live or heat-inactivated BCG. Production of circulating interferon by ectromelia virus and Newcastle disease virus was augmented in BCG-treated mice and was markedly depressed by splenectomy and antithymocyte and antimacrophage serum treatments in both BCG-treated and normal mice. Carbon clearance activity was activated in BCG-treated mice, but splenectomy did not influence phagocytic activity. These results suggest that augmented interferon production in the spleens of BCG-treated mice plays a major role in enhanced resistance. Other possible mechanisms are discussed.

Animals↗
PubMed1982

The action of phosphodiesterase inhibitors on the hypersensitivity of frog photoreceptor.

The increase in sensitivity of frog photoreceptors after illumination, "hypersensitivity", was studied by recording fast-PIII responses of the isolated bull frog retina superfused with physiological saline containing 5 mM sodium aspartate. The hypersensitivity is mot marked after illumination which bleaches only 0.01% of the rhodopsin initially present. The wavelength of light, which is optimum to induce the hypersensitivity, is about 500 nm. Several kinds of phosphodiesterase inhibitors, isobutylmethylxanthine (IBMX), papaverine, theophylline and caffeine act to induce the hypersensitivity, as does lowered extracellular concentrations of calcium ion, [Ca2+]out. Such action of phosphodiesterase inhibitor can be antagonized by an increase in [Ca2+]out. The relation between effects of Ca2+ and cyclic nucleotides on photoreceptor is discussed.

1-Methyl-3-isobutylxanthine↗