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Biomedical subjects

A Aoki

Publications and source records attributed to A Aoki.

At least 145 records · Page 8Linked to original sources
PubMed1990

Long-term potentiation-induced synaptic changes in hippocampal dentate gyrus of rats with an inborn low or high learning capacity.

Structural changes induced by high frequency (HF) stimulation on granule cells of the hippocampal dentate gyrus of rats with inborn high (HP) and low (LP) learning capacity was examined in this study. Two types of axodendritic synapses were processed morphometrically; the axonal bouton on dendritic shafts and those making contact through dendritic spines. The occurrence of granule cell spine synapses on LP rats before tetanus is less than the one in control animals. However, after long-term potentiation (LTP) produced by HF stimulation the number of spine synapses decreased, as happened in the control rats. Moreover, the number of granule cells shaft synapses counted on LP rats, before tetanus is less than the one on control rats, and after LTP this number increased greatly. There was no change in the number of granule cell shaft synapses in HP rats before and after LTP. LP rats which did not show LTP in spite of HF stimulation did not show changes in the number of spine and shaft synapses. From these results we can conclude that: (1) the great hippocampal synaptic plasticity observed in HP rats compared to LP rats can be attributed, at least in part, to the increased number of spine and shaft synapses observed in HP rats; (2) the minor number of spine and shaft synapses in LP rats may account for the impossibility to obtain LTP after HF stimulation in these animals.

Animals↗
PubMed1990

Extraction of rat pituitary prolactin for radioimmunoassay.

The bulk of Prolactin (PRL) in rat pituitary gland stored as big molecular forms in secretory granules is mostly excluded from radioimmunoassay (RIA) determinations because secretory granules remain intact after tissue homogenization. Also big PRL is little immunoreactive and must be deaggregated to monomers to allow a complete detection by RIA. Different dissociating agents, used to render PRL monomers soluble, were tested at various temperatures and pH conditions. Incubations of pituitary homogenates in buffers at neutral pH yield consistent levels of PRL, but the sole alkalinization of the media increases significantly the radioimmunoassayable PRL content. No significant increase was detected with EDTA and thiols. The 2.5 M urea was the most effective extraction agent increasing about 7-fold the quantification of PRL by RIA. Extraction of PRL with urea was enhanced at pH 9.0 and at 4 C and this combination constitutes the method of choice for a complete extraction of pituitary PRL.

Animals↗
PubMed1990

In vitro sensitivity of human hematopoietic progenitor cells to hyperthermia: critical temperature for cells to survive and its application to in vitro purging.

Normal tissue toxicity is a major concern in cancer therapy. Since the hyperthermic killing of normal human hematopoietic progenitor cells including multilineage progenitor cells (CFU-mix) other than committed granulocyte-macrophage progenitor cells (CFU-GM) is not known, we have studied the thermal sensitivity of various types of human hematopoietic progenitor cells: early and late erythroid progenitors (CFU-E and BFU-E), CFU-GM and CFU-mix using semisolid clonogenic assays. When these progenitor cells were exposed at 42-44 degrees C for 2 h, their thermal sensitivity always appeared to be in the order of CFU-E greater than BFU-E greater than CFU-GM greater than CFU-mix; the CFU-mix was the most tolerant to heat damage. In addition, the survival of human hematopoietic progenitor cells decreased exponentially in exposure time- and temperature-dependent manner. At 44 degrees C human hematopoietic progenitor cells including CFU-mix dropped dramatically in number and therefore were unable to form colonies in vitro after exposure for 2 h. This suggests that 44 degrees C may be the critical temperature for the CFU-mix to survive in vitro. Thus temperatures selected for hyperthermia used to purge residual leukemic cells in remission marrow grafts should be 43 degrees C or lower.

Cell Survival↗
PubMed1990

Improved prolactin crop-sac bioassay applying a morphometric approach.

A pigeon crop-sac bioassay for prolactin was developed applying a morphometric approach for quantification of the epithelial cell proliferation induced by the hormone. A small male dove, indigenous from South America (Zenaida auriculata) previously castrated was used as experimental animal. The total dose of prolactin was divided into 4 daily injections administered systemically into the pectoral muscles. The number of the proliferated cell layers used as the bioassay end point was analyzed statistically. This procedure yields a highly sensitive bioassay with an excellent precision index, particularly well suited for quantification of the different molecular forms of pituitary PRL.

Animals↗
PubMed1990

[Serum type III procollagen N-terminal peptide in patients with collagen diseases].

The serum concentration of type III procollagen N-terminal peptide (P III P) level is known to reflect the activity of collagen biosynthesis. To analyze the correlation between the disease activity and serum P III P levels in collagen diseases, serum P III P levels in patients with rheumatoid arthritis (RA), progressive systemic sclerosis (PSS), and other collagen diseases were measured. In some patients serum levels of prolyl++-hydroxylase, which is an intra-cellular enzyme of collagen biosynthesis, were measured. Serum P III P levels were elevated in patients with PSS and MCTD/overlap syndrome, suggesting a high rate of collagen biosynthesis by fibroblasts. Patients with RA showed no significant elevation of serum P III P compared with normal control group. But the group of RA patients with elevated ESR and/or serum CRP values showed high levels of serum P III P. The correlation between the disease activity and serum P III P levels was observed in RA patients with positive rheumatoid factor (RF), but not patients without RF. In addition we measured P III P levels in synovial fluid of RA and osteoarthritis patients. The levels were one to three hundred times higher than serum levels, and they showed the positive correlation with serum levels, suggesting that serum P III P might be originated from synovial P III P.

Adult↗
PubMed1990

[Their titers and recognized molecules of IgG class anti-BCG antibody in sera from patients with tuberculosis].

Hypergammaglobulinemia is a frequent complication of tuberculosis. Serum levels of each class of immunoglobulin were analyzed among tuberculosis patients. Adult patients had high levels of IgG and IgA, but IgM levels were not elevated. These data suggested that antibody responses to mycobacterial antigens might be influenced by individual immune responses. In order to analyze the specific antibody responses to mycobacterial antigens, IgG class antibodies reactive with BCG proteins were enumerated by an enzyme-linked immunosorbent assay (ELISA). Patients were shown to have significantly higher a mount of IgG antibodies than healthy controls. Sera from patients with active tuberculosis had high consistently titers of antibodies. Antibody titers returned to a normal range after effective treatment, suggesting that the measurement of IgG anti-BCG antibodies would be useful for the diagnosis and follow-up of tuberculosis. In addition, serum antibody profiles were analyzed by immunoblotting. Sonicated whole BCG proteins were electrophorased and transferred to nylon sheets by Western blotting. Then the sheets were developed with sera from patients or controls. Mycobacterial cell wall contains a vast array of proteins so that comparison of the antibody profiles from different sera revealed striking individual variations. However two kinds of proteins, whose molecular sizes were 65KDa and 16KDa, were considered to be significant. The 65 KDa protein was recognized in most sera from both patients and controls. The protein may be related to a "common antigen" present in a wide variety of bacteria. These observations may shed a new light on the role of 65KDa protein in the regulation of the immune systems, for example a individual highly primed to 65KDa protein may amount an exaggerated and potentially harmful response to cross-reactive antigens from other essentially non-pathogenic bacteria.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[Elective prosthetic valve reoperation to relieve unacceptably high gradient].

Pressure gradients of Lillehei-Kaster valve (13 patients), Omniscience valve (26 patients) and Omnicarbon valve (7 patients) in the aortic position were evaluated by Doppler echocardiography. Twenty-three out of 46 patients revealed unacceptably high gradients. Seven prostheses were removed because the valve design that they had high gradients across them. Clinical findings including left ventricular function and symptoms improved after the reoperation. Patients who underwent aortic valve replacement with this series of valve prostheses should be followed up cautiously.

Aortic Valve↗
PubMed1989

Effects of continuous light on rat parotid gland structure and reactivity.

The effects of continuous light on ultrastructural organization and sympathetic secretory responses of the rat parotid gland are reported. After 50 days of continuous light exposure, the fine structure of the parotid gland exhibited features of enhanced secretory activity as judged by the striking development of rough endoplasmic reticulum and Golgi complexes, the depletion of secretory granules and the increased turnover of secretory cells. The secretory responses of parotid gland to isoproterenol revealed that continuous light induced a 30% increase in amylase release. This secretory hyperactivity appears to be related to a postsynaptic supersensitivity of sympathetic fibers of the autonomic nervous system.

Amylases↗
PubMed1989

Immunocytochemical detection of estrogen receptors in a hormone-unresponsive mammary tumor.

A combination of two monoclonal antibodies and high resolution immunocytochemical technique was applied to label estrogen receptors in spontaneous mouse mammary tumors. Protein A-colloidal gold complex was used as an electron opaque marker. With this procedure estrogen receptors were labelled in the nuclei of cancer cells, predominantly over heterochromatin. In the cytoplasm a slight tagging of the rough endoplasmic reticulum was detected, apparently related with the sites of receptor biosynthesis. Other organelles and the mammary tumor viruses (MuMTV) were not stained immunocytochemically. The immunocytochemical procedure applied in this investigation allowed the detection of low levels of estrogen receptors in an estrogen-unresponsive mammary carcinoma. The presence of estrogen receptors with a specific distribution in estrogen-independent tumors suggests the need of a reevaluation of their capacity as indicators of hormone-dependence in mammary carcinomas.

Animals↗
PubMed1989

Estrogen influence on maturational pathway of murine mammary tumor virus: an immunoelectron microscopy study.

Modifications induced by estrogens on hormone-independent murine mammary tumor (MMT) and its main etiological agent, the MMT virus (MMTV), are reported. High doses of estrogens released continuously from silastic capsules delay significantly the development of transplanted tumors into syngeneic hosts. Neoplastic cells present a striking cytoplasmic vacuolization and changes in the MMTV differentiation pattern. Mature virions are detected budding into cytoplasmic vacuoles instead of the extracellular space as in spontaneous and untreated transplanted tumors. This phenomenon is reversed after estrogen withdrawal at the first sign of tumor development. Application of electron microscope immunocytochemistry with colloidal gold-protein A complex and multiple monospecific antibodies reveals several interesting features. In spontaneous and untreated tumor grafts, structural viral proteins p14 and p25 appear in both intracytoplasmic capsids and mature extracellular viruses. By contrast glycoprotein gp55 labels only the envelope of mature virus. In estrogen-treated tumors this antigenic pattern is modified and the gp55 is detected in those atypical virions maturing into the intracytoplasmic vacuoles. These observations led to the conclusions that the delay in the development of hormone-independent mammary tumors caused by estrogen is due to an abnormal maturational viral process and that estrogens induce alterations of polarity in the translocation process of viral envelope glycoproteins.

Animals↗
PubMed1989

Quantitation of autoantibody-secreting B cells in systemic lupus erythematosus.

An ELISA spot assay was used to quantitate the number of autoantibody-secreting B cells in the peripheral blood of patients with systemic lupus erythematosus. Patients with active disease had 20 fold more anti-DNA, 4 fold more anti-actin and 3 fold more anti-myosin secreting lymphocytes than controls but normal numbers of anti-cardiolipin and anti-transferrin secreting B cells. 60% of SLE patients had increased numbers of B cells reactive with multiple autoantigens. These data suggest that B cell activation in SLE may be influenced by both antigen-specific and antigen-independent factors.

Actins↗
PubMed1989

[A case report of macroamylasemia with rheumatoid arthritis].

A patient of rheumatoid arthritis complicated with macroamylasemia. Serum amylase level was persistently elevated without any apparent cause. Amylase creatine clearance ratio was reduced inspite of normal renal function. These findings suggested the presence of macroamylasemia. The abnormal molecular size of amylase isozyme was electrophoresed. Thin layer chromatography and electroimmunosyneresis revealed that the amylase binding molecule was immunoglobulin (IgA kappa type). The etiology and the clinical significance of the macroamylasemia remain unclear. Amylase binding immunoglobulin is thought to be autoantibody to amylase. Thus, the association with autoimmune diseases is suggested. However, only few cases have been reported of autoimmune diseases complicated with macroamylasemia. In this case, macroamylase appeared about 10 months after the onset of RA. Serum amylase level was inconsistent during the clinical course. Further follow-up study is considered to be important.

Amylases↗
PubMed1989

[The evaluation of pressure gradients of various aortic valve prostheses by Doppler ultrasound and influence of pressure gradients to left ventricular function].

Although the pressure gradients of heart valve prostheses has been discussed over the years, currently available valve prostheses are still not sufficient and may leave pressure gradients following aortic valve replacement. The selection of valve prosthesis and its size is still controversial. This study is aimed to measure the pressure gradients of 64 aortic valve prostheses noninvasively by means of doppler ultrasound and determine which size and what kind of valve prosthesis is suitable for aortic valve replacement. 1. Pressure gradients and LV function were serially assessed pre- and post operatively. Left ventricular mass index regressed to a normal range and the response to exercise test is quite satisfactory in the patients whose pressure gradients were less than 25 mmHg. In the cases that showed pressure gradients more than 25 mmHg, however, left ventricular hypertrophy significantly remained even 5 years after aortic valve replacement and the response to exercise was not good enough. From these results, it is concluded that the upper limit of acceptable pressure gradients is 25 mmHg in aortic valve prosthesis. 2. The pressure gradients of St. Jude Medical (SJM) valve (11 cases), Björk-Shiley (B-S) valve (7 cases), Lillehei-Kaster (L-K) valve (13 cases) and Omniscience (O-S) valve (33 cases) was evaluated to compare the hemodynamic characteristics in the long term follow-up periods. In SJM and B-S, a correlation between valve area index (geometrical valve orifice area/body surface area) and pressure gradients was significant. The valve area index more than 1.4 cm2/m2 in SJM or more than 1.7 cm2/m2 in B-S should be selected. Whereas for L-K and O-S, a correlation between valve area index and pressure gradients was not significant and it is suggested that his is due to suboptimal disc opening angle (L-K; 54 degree on the average, O-S; 46 degree on the average). For this reason, the use of these prostheses is not recommended for choice in the aortic position.

Adult↗
PubMed1989

[Preoperative perspective versus postoperative functional assessment of surgery in chronic mitral regurgitation].

Thirty patients with chronic pure mitral regurgitation who underwent mitral valve replacement during 1981 to 1986 were evaluated for pre- and one year postoperative left ventricular function using two dimensional echogram. Indicators in their evaluation were DdI, DsI, MassI and systolic and diastolic R/Th. Postoperatively, patients (n = 7) were placed in a group of abnormal responses if even one of these indicators of left ventricular function became worse than preoperative performance, patients in this group were symptomatic and two subsequently died. The postoperative FS and mVcf data fort this group were significantly lower than the patients with normal response group (n = 23). These two groups could not be differentiated by preoperative assessments of either DdI, MassI, systolic/diastolic T/Th or normalized systolic/diastolic peak velocity. However, a combination of normalized systolic peak velocity lower than 1.70 and diastolic peak velocity lower than 2.20 of left ventricular wall motion proved to be good predictors of postoperative results.

Chronic Disease↗
PubMed1989

[Emergency surgery for thrombosed Björk-Shiley mitral valve prosthesis].

A case of a thrombosed Björk-Shiley mitral valve with severe pulmonary edema which developed six years following an initial operation was reported. Doppler echocardiography was one of the most useful tools to evaluate prosthetic mitral valve dysfunction. Peak blood flow velocity was high (2.7 m/sec) compared to the data (1.7 m/sec) obtained six months before the reoperation. Emergency surgery disclosed the thrombosed valve prosthesis which was replaced with a St. Jude Medical valve. The patient recovered successfully with no problems.

Adult↗
PubMed1988

[A study on the definition of early breast cancer].

The most important factor in improving the survival rates of the patients with breast cancer is early detection. A high cure rate can be expected if the condition is discovered in early stage. There were 195 patients with primary breast cancer in our hospital from August 1978 to November 1986. Among 280 patients with breast cancer who received radical operations from July 1970 to November 1986, there were 50 patients (18%) with recurrence. Mammography and echography were effective for the diagnosis of infiltrating cancer smaller than 10mm in diameter as well as those between 11 and 20mm in diameter. None of the patients with non-infiltrating or infiltrating carcinomas smaller than 15 mm or smaller than 20 mm in diameter with negative nodes had recurrence. Consequently, at present we define early breast cancer as the lesions of pathologically noninfiltrating or infiltrating smaller than 15 mm in diameter, or infiltrating smaller than 20 mm in diameter with negative nodes.

Adenocarcinoma↗