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Biomedical subjects

H Kawahara

Publications and source records attributed to H Kawahara.

At least 19 recordsLinked to original sources
PubMed1992

The 26 S proteasome is activated at two points in the ascidian cell cycle.

The proteasome undergoes cell cycle-dependent changes in its subcellular distribution during ascidian embryonic development [(1992) Dev. Biol. 151, 27-33]. In this study, we demonstrate that the 26 S proteasome is markedly activated in both prophase and metaphase of the mitotic cell cycle in the ascidian embryos in comparison with the case of the 20 S proteasome. These results suggest that the 26 S proteasome is activated and participates in proteolysis at the restricted stages of the cell cycle.

Animals↗
PubMed1992

Eating and drinking cause increased dopamine release in the nucleus accumbens and ventral tegmental area in the rat: measurement by in vivo microdialysis.

Dopamine (DA) release was simultaneously monitored in the nucleus accumbens (NAC) and ventral tegmental area (VTA) of conscious rats using in vivo microdialysis. During dialysis perfusion, rats were allowed access to food or water for 20 min following a 36 h food and water deprivation period. DA release increased significantly in the NAC and VTA in response to eating and drinking. The increases in both regions continued until 20-60 min after the end of the feeding or drinking session. These results show that the mesolimbic DA pathway is activated in response to ingestive behavior, and that DA release occurs in the cell body (A10) region as well as in the mesolimbic DA nerve terminals.

Animals↗
PubMed1992

Stercoraceous perforation of the sigmoid colon: report of two cases.

Stercoraceous perforation of the sigmoid colon has rarely been reported in the literature. This lesion is assumed to be produced by the pressure from a hard scybalum resulting in a perforated ulcer with necrotic edges. Two cases of stercoraceous perforation of the sigmoid colon are presented in this paper. It is difficult to diagnose this lesion preoperatively, although ultrasonograms proved useful in showing the colon perforation. This lesion should always be suspected when a patient who has had chronic constipation presents with sudden severe abdominal pain. It is possible that this lesion is becoming more common as the mean age of the population increases and we stress the importance of immediate surgery and intensive care for improving the prognosis.

Aged↗
PubMed1992

Cell cycle-dependent change of proteasome distribution during embryonic development of the ascidian Halocynthia roretzi.

The proteasome is a multicatalytic proteinase complex composed of nonidentical subunits. By immunocytochemical analysis using monoclonal antibody raised against the egg proteasome, we demonstrate that the proteasome undergoes changes in its subcellular distribution, depending on the cell division cycle during embryonic development of the ascidian Halocynthia roretzi. During interphase, the proteasome is localized in the nucleus, i.e., in the nucleoplasm and along the nuclear membrane. The proteasome disappears from the nucleoplasm in prophase and from the nuclear envelope in prometaphase. During early metaphase, the proteasome is detectable in the chromosomes and, at late stages of metaphase, the immunoreactivity also occurs in the peripheral region of each spindle pole and at the mitotic spindle. In anaphase, however, the staining disappears in the mitotic apparatus. In telophase, the proteasome is again localized in the newly formed nucleus. In addition to the localization in the nucleus and around the mitotic apparatus, the proteasome shows cytoplasmic localization throughout the cell division cycle. Such a change of subcellular distribution of the proteasome is clearly demonstrated in the synchronously dividing blastomeres and also is believed to occur in the postcleavage embryos. These observations suggest that the proteasome may play a key role in the progression of cell division cycle.

Animals↗
PubMed1992

Differential phosphorylation of CK8 and CK18 by 12-O-tetradecanoyl-phorbol-13-acetate in primary cultures of mouse hepatocytes.

The phosphorylation of cytokeratin was investigated in primary cultures of hepatocytes. The two hepatocyte cytokeratins CK8 and CK18 (55,000 and 49,000 M(r) respectively) were phosphorylated, CK8 being more phosphorylated than CK18. Treatment of the hepatocytes with 150 nM 12-O-tetradecanoyl-phorbol-13-acetate (TPA) an activator of protein kinase C induced a transient increase in the level of phosphorylation of CK8 but not CK18. This effect was maximal after 15 min of TPA treatment and was maintained for up to 3 h. After 22 h of treatment with TPA, which down-regulates protein kinase C, CK8 phosphorylation was returned to the basal level. Further addition of TPA to the 22-h treated cells did not cause an increase in CK8 phosphorylation. Indirect immunofluorescence microscopy with a monoclonal antibody to CK8 indicated that while the addition of TPA induced the formation of granular cytokeratin aggregates in some hepatocytes, in most hepatocytes no major changes in the intermediate filament network were observed. Staining for actin showed that actin microfilaments were rapidly reorganized after the treatment and a loss of stress fibres were observed. We propose that CK8 is an in vivo substrate for protein kinase C and that the specific phosphorylation of CK8 plays a role in protein kinase C signal transduction.

Animals↗
PubMed1992

Immunohistochemical demonstration of bone morphogenetic protein-2 and transforming growth factor-beta in the ossification of the posterior longitudinal ligament of the cervical spine.

To clarify the mechanism of ossification of the posterior longitudinal ligament, immunohistochemical localization of bone morphogenetic protein-2 and transforming growth factor-beta was examined using surgical specimens of ligament tissues from an affected patient. Two polyclonal antibone morphogenetic protein-2 antibodies and an anti-human transforming growth factor-beta antibody were used as primary antibodies. Bone morphogenetic protein-2 and transforming growth factor-beta were present in ossified matrix and chondrocytes of adjacent cartilaginous areas of ossification of the posterior longitudinal ligament. Although immunostaining with antibone morphogenetic protein-2 antibodies also was observed in mesenchymal cells with fibroblastic features in the immediate vicinity of the cartilaginous areas, no staining could be detected with anti-human transforming growth factor-beta antibody in these cells. The presence of these factors were specific for the ossified ligament because no immunostaining was observed after using antibodies in the posterior longitudinal ligament at unossified levels from the same patient. It is suggested that bone morphogenetic protein-2 and transforming growth factor-beta play important roles in the development of ossification of the posterior longitudinal ligament and that bone morphogenetic protein-2 may act as an initiating factor in the development of ossification of the posterior longitudinal ligament by stimulating differentiation of mesenchymal progenitor cells. Transforming growth factor-beta may stimulate bone formation at a later stage of the process of ectopic ossification.

Aged↗
PubMed1992

Clinical and neuroradiologic findings of congenital hydrocephalus in infant born to mother with HTLV-I-associated myelopathy.

We describe clinical and neuroradiologic findings in a male infant with congenital hydrocephalus born to a mother who developed human T-cell lymphotropic virus type I (HTLV-I)-associated myelopathy. Ultrasonography at age 20 days showed multiple cysts in the subependymal germinal matrix and enlarged lateral ventricles. Elevation of serum HTLV-I antibody suggested that his hydrocephalus was probably due to intrauterine HTLV-I infection. HTLV-I may cause neurotropic infection in utero.

Female↗
PubMed1992

Preoperative radiation for carcinoma of the thoracic esophagus involving adjacent organs--a comparative and multivariate analysis of prognosis.

Controversy remains over the comparative efficacy and subsequent prognosis for preoperative radiation for carcinoma of the esophagus involving the trachea, bronchus, and/or aorta. Results of a multi-variate analysis are reported using clinical data from 57 cases from 1981 to 1987. Based on both the survival-rate curves using the Kaplan-Meier method and the adjusted survival-rate curves using Cox's proportional hazards linear model, there was no significant difference in prognosis between patients who received preoperative radiation and those who did not. This analysis indicates that preoperative radiation at doses of 30Gy produces no clinical advantage and therefore is not the best treatment for carcinoma of the esophagus involving these adjacent organs.

Aged↗
PubMed1992

Questionable resection for carcinoma of the esophagus involving the trachea, bronchus and/or aorta--a comparative and multivariate analysis.

Controversy remains over the comparative efficacy and subsequent prognosis of resections for carcinomas of the esophagus involving the trachea, bronchus, and/or aorta. Results of a multi-variate analysis are reported using clinical data from 103 cases from 1981 to 1987. Based on the survival-rate curves according to the Kaplan-Meier method, resection was superior to non-resection. However, when other prognostic factors were adjusted using Cox's proportional hazards linear model, there was no significant difference between the resection and non-resection groups. This analysis indicates that esophagectomy is not necessarily the best approach for carcinoma of the esophagus involving these adjacent organs, although it must be remembered that resection provides excellent palliation.

Aged↗
PubMed1992

[Investigation of two cases of adenoid cystic carcinoma of the esophagus].

A 59-year-old man and a 55-year-old man with adenoid cystic carcinoma of the esophagus are presented. They were also treated with esophagectomy but whose prognosis were significantly different. The former has been still alive for 3.5 years and the later died at 7 months after the operation. In the patient with good prognosis, the tumor was 1.6 x 1.2 cm in size and pathologically invaded muscularis propria (mp) with no metastases to lymph nodes (pathological stage I). It has been reported that the prognosis of adenoid cystic carcinoma of the esophagus is poorer than that of other histological type of carcinomas. However, it is suggested that if the tumor can been resected when it is small in size with no metastases, it will be able to expect for good prognosis as in this presentation.

Carcinoma, Adenoid Cystic↗
PubMed1992

Surgical treatment of hemodialysis-related shoulder arthropathy.

Thirteen patients with hemodialysis-related shoulder arthropathy were treated either with arthroscopic synovectomy or with open surgery. Arthroscopic synovectomy was performed in eight patients who had shoulder pain, shoulder immobility or both but did not have cystic bone lesions. The therapy was effective for pain relief and improvement of shoulder function for six months but in 12 months the shoulder pain reappeared in most of the patients. Open surgery was done in 5 patients who, in addition to shoulder pain and immobility, had humeral head bone cysts. Resection of the deposited mass on the biceps tendon sheath, of hypertrophied synovium and bursa as well as curettage of cysts and calcium hydroxyapatite ceramic implantation were performed. The therapy was effective for pain relief throughout the follow-up period (12 months). No adverse effects were noted for either procedure. Resected specimens of the synovia contained amyloid as indicated by a positive Congo-red stain by light microscopy and the presence of amyloid fibrils by electron microscopy. Deposition of amyloid in the biceps tendon sheath, synovium and bursa and invasion of the humeral head by amyloid were observed upon open surgery. The results suggest that the resection of deposited material induces the improvement of the shoulder arthropathy.

Amyloidosis↗
PubMed1992

In vitro immunization of human lymphocytes with human lung cancer cell line A549.

We established a method of in vitro immunization of human lymphocytes against human cancer cells and efficiently obtained human-human hybridomas producing cancer-specific antibodies using the in vitro immunized lymphocytes. Human lymphocytes were cocultured with human lung cancer cell line A549 for four days in medium containing various immunoactive reagents. In vitro immunization was effectively caused by the addition of OK-432 or muramyl peptides, IL-2, and IL-6, to the coculture of A549 cells and lymphocytes. Although specific antibodies of both IgM and IgG classes were produced by this method, the ratio of IgG to IgM was greater than or equal to 2. The efficiencies of in vitro immunization fluctuated about threefold in lymphocytes derived from several donors. The in vitro immunized lymphocytes were fused with human fusion partner A4H12 cells. Hybridomas producing specific antibodies reactive to A549 cells were efficiently obtained by sequential cell fusion. The efficiency of acquisition of hybridomas producing specific antibodies with the in vitro immunized lymphocytes was about 10-fold higher than that with lymphocytes spontaneously immunized in bodies of lung cancer patients.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1992

A new surgical technique for voice restoration after laryngopharyngoesophagectomy with a free ileocolic graft: preliminary report.

We describe a new one-stage surgical technique for voice restoration combined with reconstruction of the cervical esophagus after laryngopharyngoesophagectomy with a free ileocolic autograft. Reconstruction of the alimentary tract is accomplished with the colonic segment, and the phonatory shunt is fashioned from the terminal ileum. The ileocolic valve, reinforced by "cecal application," functions as an inherent valve that prevents aspiration through the shunt. Six patients underwent reconstruction with this method. There was no graft necrosis, although one venous anastomosis required correction because of kinking. There were two hospital deaths: one patient died of multiple organ failure in the perioperative period and the other died of a recurrence of the disease. The remaining four patients were tolerating a regular diet at discharge from the hospital. Five of the six patients were able to achieve a fair to good voice.

Aged↗
PubMed1991

Increased antigen binding strengths of hybrid antibodies produced by human hybrid hybridomas.

Two cell lines of human hybridomas were fused to generate hybrid antibodies. One human hybridoma cell line was HT2 producing IgM monoclonal antibody (MAb) reactive to carboxy peptidase A (Cpase) and double stranded DNA (ds DNA) and another was SU-1-D2 secreting IgM MAb reactive to ds DNA but not to Cpase. Most hybrid hybridomas obtained by fusion of the two hybridomas secreted hybrid antibodies exhibiting increased antigen binding strengths. All of the hybrid antibodies with increased binding strengths against Cpase and ds DNA contained only the light chains derived from SU-1-D2. These results suggested that increase in the binding strength of the hybrid antibodies resulted from heterogeneous association of H and L chains derived from HT2 and SU-1-D2 cells.

Antibodies, Monoclonal↗
PubMed1991

A comparative study of atherosclerosis and osteopenia in elderly and young hemodialysis patients.

The effects of aging on atherosclerosis and osteopenia in hemodialysis patients were investigated. Eighty patients on maintenance hemodialysis were subdivided according to age into old (greater than or equal to 65 years old, N = 40) and young (less than 65 years old, N = 40). Biochemical, radiologic, and biophysical studies were performed in each patient to assess the degree of atherosclerosis and osteopenia. Compared to age-matched controls, patients in the old group exhibited a significantly higher aortic pulse wave velocity (PWV), and old female patients had a significantly lower bone mineral content/bone width (BMC/W). Elderly patients also had a significantly higher aortic PWV and higher grade of aortic calcification as assessed radiologically; in contrast, the BMC/W was lower. Concerning sex differences, elderly male patients had the highest average grade of aortic calcification, the lowest serum Pi, [Ca] x [Pi], and immunoreactive parathyroid hormone concentrations, while elderly female patients had the lowest BMC/W and highest incidence of osteopenia. These observations suggest that elderly male hemodialysis patients are more prone to develop atherosclerosis and elderly female hemodialysis patients to develop advanced osteopenia.

Adult↗
PubMed1991

Comparative studies on proteasomes (multicatalytic proteinases) isolated from spermatozoa and eggs of sea urchins.

1. Proteasomes (multicatalytic proteinases) have been purified from spermatozoa and eggs of sea urchins by successive chromatographies on DEAE-cellulose, hydroxylapatite, and Sepharose 6B. 2. The isolated sperm and egg proteasomes showed similar properties such as molecular weight (both 630,000) and multiple catalytic activity (pH optimum, substrate specificity, inhibitor-susceptibility and SDS-stimulation). 3. Distinct protein components were detected between sperm and egg proteasomes by SDS-polyacrylamide gel electrophoresis and immunoblot analysis using antibody against egg proteasome.

Amino Acid Sequence↗