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A Segawa

Publications and source records attributed to A Segawa.

At least 55 records · Page 3Linked to original sources
PubMed1989

Roles of microfilaments in exocytosis: a new hypothesis.

We observed the dynamic changes in the localization of microfilaments during the exocytic secretion of rat parotid and submandibular gland acinar cells, and obtained results which led us to propose a new concept of microfilament function in exocytosis. With the electron microscopy, NBD-Phallacidin (NBD-PL) fluorescence technique and immunohistochemistry for myosin, microfilaments consisting of F-actin and myosin were localized mainly underneath the luminal plasma membrane. Microfilaments were not detectable around the secretory granules which were stored in the cytoplasm, but were clearly observed around them whose membranes were continuous with the luminal plasma membrane. When viewed with NBD-PL and myosin fluorescence, the area of fused granule membranes revealed bright fluorescence in association with the luminal border, so that the luminal membrane undergoing exocytosis appeared like a 'bunch of grapes'. When excess exocytosis was stimulated by isoproterenol (IPR), the number of individual 'grapes' increased dramatically, indicating that the secretory granules are surrounded by microfilaments after the fusion with the luminal membrane. Microfilaments thus continuously undercoat the luminal membrane during exocytosis although the exocytic process involves the dilation and subsequent reduction of the luminal membrane due to the addition and removal of secretory granule membranes. This reduction of the dilated luminal membrane following exocytosis was, however, inhibited when the microfilaments were disrupted by cytochalasin D. Following this treatment, the lumina was expanded extraordinarily and the secretory products remained in the enlarged lumina, showing that the release of secretory products is inhibited when the microfilament function is disturbed. These results indicate that 1) microfilaments are localized mainly underneath the luminal plasma membrane and act as an obstacle to exocytosis when cells are at the resting phase and 2) at the secretory phase microfilaments allow exocytosis by disorganizing their barrier system and then, by encircling the discharged secretory granule membranes, provide forces for the extrusion of secretory products through the action of the acto-myosin contractile system.

Actin Cytoskeleton↗
PubMed1989

[Treatment of gonococcal urethritis with norfloxacin].

Fifty six males with gonococcal urethritis were administered 600 mg of norfloxacin (NFLX) daily for 7 days, before the effects were examined. The pharmaceutical effects were studied on the third and the seventh day after administration. Pronounced effectiveness of 77.8%, effectiveness of 19.4% and ineffectiveness of 2.8% were found on the third day after administration, and pronounced effectiveness of 94.4%, effectiveness of 5.6% and ineffectiveness of 0% were found on the seventh day after administration. Effectiveness of 100% was obtained up to the seventh day. Minimum inhibitory concentration (MIC) of NFLX and ampicillin (AMPC) were determined for 14 strains. The peak of MIC of NFLX was found at 0.05 micrograms/ml and all strains were 0.78 micrograms/ml or lower. The peak of MIC of AMPC was 0.1 microgram/ml. MICs of both drugs were 0.78 micrograms/ml or lower, and resistant bacteria were not found. In view of the analyses of age distribution of patients and source of infection, the peak was found in the twenties and the source of infection in 64.7% were, so-called, professional women.

Adult↗
PubMed1989

[A case of signet ring cell carcinoma of the urinary bladder].

A 67-year-old man was admitted for complaint of gross hematuria on April 9, 1986. Cytoscopic examination was revealed broad-base tumor, its size was thumb's head, at the right lateral wall of the bladder. Ultrasonography and computed tomographic scan of the bladder demonstrated no evidence of invasion to adjacent organs. The biopsy showed signet-ring cell carcinoma. Radiography of the digestive organs showed no abnormality. A partial cystectomy was performed. Histologically the tumor was limited up to submucosa, that is pT1b. The localization of carcinoembryonic antigen (CEA) on tissue of our case, using the peroxidase-antiperoxidase (PAP) method, was evidenced.

Adenocarcinoma, Mucinous↗
PubMed1989

[The optimum dose of iohexol 399 in excretory urography].

A randomized clinical trial was conducted to determine the optimum does of iohexol (iodine concentration 300 mgI/ml) as a contrast agent for excretory urography in screening outpatients. Cases were divided into two groups, 30 cases in Group A receiving 0.4 ml/kg of iohexol and 29 cases in group B receiving 0.8 ml/kg. Urography was performed at intervals of 5 minutes and 10 minutes following the injection. The diagnostic effectiveness of various X-ray images including nephrograms, the pyelocaliceal system, ureter and bladder were assessed. There was a significant disparity between the two groups during pyelocaliceal urography after 5 minutes, with a fair diagnosis attainable for 73.3% of group A versus 89.6% for group B (P less than 0.05), but after 10 minutes the rates for the two groups had evened out to 93.4% for group A and 96.6% for group B. During urography of the ureter after 5 minutes, only 16.6% of the cases in group A could be easily diagnosed against 51.7% of the cases in group B (P less than 0.05). However, after 10 minutes the rate for group A was up to 56.7% while the rate for group B was 82.8% (P less than 0.1). In the ureter after 5 minutes, non-diagnosable images constituted 26.7% of group A and 10.4% of group B, while after 10 minutes this had dropped to 16.6% for group A and 0% for group B. A comprehensive study of these results suggests that for diagnostic screenings which use iohexol as a contrast agent in excretory urography, optimal results may be obtained using iohexol in amounts of between 0.4 ml/kg and 0.8 ml/kg.

Ambulatory Care↗
PubMed1989

[Long ureteral polyp: a case report].

A case of long ureteral polyp is presented. The patient was a 62-year-old woman complaining of asymptomatic macrohematuria. Radiological examinations revealed ureteral tumor. A tumor was found with cystoendoscopy, and by transurethral biopsy in bladder the tumor was not malignant. Polypectomy was performed. The tumor removed was fibrous polyp measuring about 8 cm in length.

Female↗
PubMed1988

Calcium is essential in the fusion of mouse alveolar macrophages induced by 1 alpha,25-dihydroxyvitamin D3.

We have reported that the active form of vitamin D3, 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3], directly induces activation and fusion of mouse alveolar macrophages (Abe et al., 1983, 1984). The activated state appeared to be a prerequisite to the fusion of macrophages. Macrophages began to fuse 36 hr after adding 1 alpha,25(OH)2D3; the fusion rate attained a maximum of 70-80% at 72 hr. During the course of further investigating the mechanisms of fusion induced by the vitamin, we found that the calcium ion is closely involved in the fusion process of macrophages induced by 1 alpha,25(OH)2D3. When alveolar macrophages were cultured with 1 alpha,25(OH)2D3 in medium with graded concentrations (0.13-1.85 mM) of calcium, the fusion rate went down in parallel with the decrease of medium calcium. Neither calcium ionophore A23187 nor 12-O-tetradecanoylphorbol-13-acetate (TPA) induced fusion of freshly isolated macrophages, but the two compounds greatly promoted fusion of the macrophages pretreated for 18 hr with 1 alpha,25(OH)2D3. The vitamin effect for the first 18 hr was similar, irrespective of the medium calcium concentration. In contrast, millimolar amounts of calcium were essential in the subsequent period of incubation(18-72 hr) for inducing fusion. The activation of macrophages measured by the induction of cytotoxicity and the enhancement of glucose consumption by 1 alpha,25(OH)2D3 occurred similarly, irrespective of the medium calcium concentration. These results clearly indicate that the fusion process of alveolar macrophages induced by 1 alpha,25(OH)2D3 can be divided into two phases: 1) the calcium-independent priming phase (0-18 hr) and 2) the calcium-dependent progression phase (18-72 hr). 1 alpha,25(OH)2D3 is necessary only in the priming phase; A23187 and TPA can be substituted for 1 alpha,25(OH)2D3 in the progression phase.

Animals↗
PubMed1987

An ultrastructural study on the multinucleation process of mouse alveolar macrophages induced by 1 alpha,25-dihydroxyvitamin D3.

The multinucleation process of isolated alveolar macrophages induced by 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3] was examined using a scanning electron microscope (SEM) and a transmission electron microscope (TEM). At the beginning of culture, most of the macrophages were spherical in shape. During incubation with 1.2 X 10(-8) M 1 alpha,25(OH)2D3, spreading macrophages appeared among the spherical macrophages, and they increased in number. Spreading macrophages extended many cytoplasmic processes toward adjacent macrophages, and interdigitations of these processes between those of neighboring cells were often seen. Two types of cell contact have been observed in the 1 alpha,25(OH)2D3-treated cells. In some, cytoplasmic processes were put into the cytoplasm of the adjacent cells, where clathrinlike structures were observed at the inner membrane of the concave portion. In others, spreading macrophages occasionally came in contact with adjacent cells by a peripheral rim of their cytoplasm with gap junctions. Cytoplasmic continuity was rarely observed at the boundaries between the closely associated cells. The two types of cell contact were also found, though not frequently, in the untreated cells. These results indicate that 1 alpha,25(OH)2D3 promotes multinucleation of alveolar macrophages through spreading forms with the formation of gap junctions and the coated membrane invagination.

Animals↗
PubMed1986

Effects of retinoic acid on the activation and fusion of mouse alveolar macrophages induced by 1 alpha,25-dihydroxyvitamin D3.

1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3] directly induces both fusion and cytotoxicity in murine alveolar macrophages. Unlike 1 alpha,25(OH)2D3, retinoic acid per se did not induce fusion of alveolar macrophages, but it greatly enhanced the 1 alpha,25(OH)2D3-induced fusion every time the macrophages were treated simultaneously with the two vitamins. The giant cells induced by the two vitamins were much larger than those induced by 1 alpha,25(OH)2D3 alone. The macrophages treated with 1 alpha,25(OH)2D3 started to fuse 36 h after the addition of the vitamin, whereas the macrophages pretreated with retinoic acid for 24 h began to fuse immediately after 1 alpha,25(OH)2D3 was added. 1 alpha,25(OH)2D3 and retinoic acid activated alveolar macrophages similarly, measured by the enhancement of glucose consumption and the induction of cytotoxicity against tumor cells, though 1 alpha,25(OH)2D3 was 100 times more potent than retinoic acid on a molar basis. Simultaneous treatment with physiological concentrations of 1 alpha,25(OH)2D3 (0.12 nM) and retinoic acid (10 nM) induced cytotoxicity additively. Morphological examinations revealed that the treated cells were enlarged and flattened with numerous filopodia. These results clearly indicate that both 1 alpha,25(OH)2D3 and retinoic acid similarly activate alveolar macrophages, and the activated state is prerequisite to the fusion of macrophages induced by 1 alpha,25(OH)2D3.

Animals↗
PubMed1985

Acinar structure and membrane regionalization as a prerequisite for exocrine secretion in the rat submandibular gland.

The significance of glandular organization in exocrine secretion was examined by analysing the functional and morphological features of the dissociated rat submandibular gland with special reference to the acinar structure and luminal specialization. The digestion of the gland with collagenase (C preparation) produced relatively large cellular masses having well-preserved acinar structures. When EGTA and the proteolytic enzyme Dispase were added to the C preparation (CED preparation), the gland was dissociated into small cellular aggregates in which the acinar structure disintegrated. Upon stimulation with either isoproterenol or dibutyryl cyclic AMP, a large amount of peroxidase, one of the secretory products of the rat submandibular gland, was released from C-treated cells, while discharged peroxidase was greatly reduced after the CED preparation was used. Measurements of dye exclusion, oxygen consumption, protein synthetic activity and receptor binding, as well as ultrastructural features and the absence of inhibitory effects of EGTA and Dispase, suggested that the reduced secretory response of CED-treated cells was not attributable to cellular death, denaturation of receptors or the inhibitory effects of EGTA and Dispase. When the localization of dipeptidyl aminopeptidase IV was surveyed by both enzyme histochemistry and immuno-histochemistry, the luminal plasma membrane was the exclusive site for the reaction in C-treated cells as well as intact acini, whereas the entire cell surface was reaction-positive in CED-treated cells. In addition, the luminal microfilament system and tight junctions, as revealed by nitrobenz-oxadiazole-phallacidin staining and freeze-replica studies, respectively, were well-preserved in the C-treated cells, but considerably disorganized in the CED-treated cells. All these results strongly suggest that: (1) luminal specialization plays an important role in exocrine secretion; and (2) normal acinar arrangement provides the luminal specialization.

Animals↗
PubMed1985

[Alterations in urinary N-Acetyl-beta-D-glucosaminidase (NAG), beta 2-microglobulin (BMG) under acute exposure to simulated 6,000 m altitude].

The changes in NAG and BMG concentration in the urine during sudden exposure to a simulated 6,000 m altitude (354 mmHg) were studied. Subjects were 5 healthy male volunteers before a mountain climbing expedition (20-25 years old). Decompression was commenced at 11:00 and terminated at 17:00 (2-h ascent, 2-h sojourn, 2-h return) for 5 successive days. Urine was discarded at 9:00 and thereafter collected at 11:00 (group I), 14:00 (group II) 17:00 (group III), and 9:00 the next day (group IV) and urinary NAG and BMG was measured. The rate of NAG indicated elevation above 5.0 U/L in 2 cases in group III and elevation which was significantly different from that of the other 3 groups. In the other 3 cases, significant elevation was not observed, but for group III as a whole NAG excretion was significantly elevated compared of the other 3 groups. However, increased excretion of NAG was not observed on all 5 successive days. The change in BMG values was smaller than that of the NAG values and no significant elevation was observed in any of the 4 groups. Increasing urinary excretion of NAG by sudden exposure to a high altitude indicated excessive destroy of epithelium in the proximal tubules, but this change was reversible.

Acetylglucosaminidase↗
PubMed1984

[Surgical method of retropubic prostatectomy].

The retropubic prostatectomy is performed mostly for prostatic hypertrophy. By performing the preventive suture-ligation of the bilateral prostatic arteries which are running among the vesicoprostatic pedicle before prostatectomy, massive bleeding from bladder neck and prostatic bed can be controlled well, and ligation of bilateral spermatic cord prevents retrograde epididymitis. This surgical procedure makes retropubic prostatectomy easy.

Aged↗
PubMed1984

[Clinical evaluation of lymphoscintigraphy in urological disease].

Clinical efficacy of lymphoscintigraphy was evaluated in 31 cases of urological disease. To diagnose metastatic change of malignant tumor, 99mTc-rhenium colloid (5mCi) was administrated from bilateral pedal region. Of these patients 12 had true positive finding, 2 had false positive finding, 2 had false negative finding, and 8 had true negative finding defined by lymphoscintigram and pathological finding. Overall accuracy of lymphoscintigraphy revealed 83% in correlation of pathological finding, 78% in lymphangiography. Accuracy between lymphangiography and pathological finding was 80%. The overall clinical efficacy of lymphoscintigraphy was the same as lymphangiography. The merit of this method was that we can examine easily, painlessly, and frequently.

Adult↗