Biomedical subjects

T Sakai

Publications and source records attributed to T Sakai.

At least 505 records · Page 28Linked to original sources

PubMed1998

Prolactin-producing cells differentiate from G0/G1-arrested somatotrophs in vitro: an analysis of cell cycle phases and mammotroph differentiation.

In order to analyze the relationship between cell proliferation and mammotroph differentiation, we studied a somatotrophic cell line, MtT/S. MtT/S cell is known to differentiate into PRL-producing cells in response to stimulation with insulin or insulin-like growth factor-1 (IGF-1). Double immunostaining for bromodeoxyuridine (BrdU), which labels proliferating cells, and for GH or PRL showed that most BrdU-labeled cells were GH-immunopositive, whereas considerably few PRL-positive cells were labeled with BrdU. This was confirmed by immunostaining of proliferating cells with antibody to proliferating cell nuclear antigen (PCNA). Furthermore, flow-cytometry analysis indicated that most of the PRL-producing cells were in the G0/G1 phase of the cell cycle. In order to determine whether cell cycle changes are required for transdifferentiation of PRL-producing cells, MtT/S cells were cultivated in serum restricted medium for 7 days to reduce their mitotic activity and then treated with insulin and epidermal growth factor (EGF). Under these conditions, the cell cycle of MtT/S cells was significantly delayed, but the percentage of PRL-producing cells induced was almost identical to that under control conditions, showing that mitosis is not required for PRL- producing cell differentiation. We also labeled MtT/S cells with BrdU for 24 h during PRL-producing cell induction by insulin and EGF, and as a result BrdU-labeled proliferative cells were specifically absent from PRL-producing cell populations. These data, taken as whole, suggest that PRL cells differentiated from G0/G1 arrested somatotrophs and the PRL cells which appeared had their cell proliferation activity significantly declined. In conclusion, this is the first report showing the relationship cell between proliferation and differentiation of PRL cells.

Animals↗

PubMed1998

Point mutation in exon 12 of the receptor tyrosine kinase proto-oncogene RET in Ondine-Hirschsprung syndrome.

A 5-year-old girl with congenital central hypoventilation syndrome associated with Hirschsprung's disease (Ondine-Hirschsprung syndrome) representing a missense mutation in exon 12 of the receptor tyrosine kinase (RET) proto-oncogene is reported. Using a direct sequencing technique, genomic DNA obtained from the patient's peripheral leukocytes was analyzed for its nucleotide sequences in all 20 exons of the RET proto-oncogene, seven regions of the 1st to the 7th exon of the endothelin-B receptor gene and endothelin 3 gene, including sequences corresponding to proteolytic cleavage sites. The analysis revealed that adenine at the 2116th base in the 12th exon in the RET proto-oncogene was substituted by guanine, supposedly resulting in a mutation of Thr 706 to Ala. No other mutational change was observed in the gene examined in this case. Mutation analysis has not been described previously on the gene in this disease complex. Mutation in this case might impair the maturation of the tyrosine kinase protein and subsequently cause neurocristopathy supposedly originating from the neural crest.

Amino Acid Sequence↗

PubMed1998

First sporadic cases of non-pneumonic legionellosis, Pontiac fever in Japan.

Pontiac fever has rarely been found in sporadic cases. Here, we report the first sporadic cases of non-pneumonic legionellosis, Pontiac fever in Japan. Case 1. A 53-year-old man with spinocerebellar degeneration was presented to our hospital. He had an acute onset of high fever and consciousness disturbance. A chest X-ray film on admission was normal, but transient bilateral pleural effusions were revealed on hospital day 14. Case 2. A 77-year-old woman with gastric ulcer was presented to our hospital. She had an acute onset of high fever. A chest X-ray film on admission was normal, but transient bilateral pleural effusions were revealed on hospital day 7. High fever, resistant to beta-lactam antibiotics, continued in both cases. Both had serologic confirmation of legionellosis by indirect fluorescent antibody assay for Legionella pneumophila without seroconversion for Mycoplasma pneumoniae, and Chlamydia pneumoniae, and had a good prognosis. Both were thought to be sporadic community-acquired cases rather than epidemics.

Acute Disease↗

PubMed1998

Serum paraoxonase activity and genotype distribution in Japanese patients with diabetes mellitus.

We investigated the serum paraoxonase (PON) activity and genotype distribution in 139 patients with non-insulin-dependent diabetes mellitus and in 240 control subjects in a Japanese population. There were no significant differences in PON genotype frequencies between the diabetic and control subjects, but the PON activity was significantly less in diabetic subjects (p<0.01). PON activity was significantly related to levels of total cholesterol and high density lipoprotein (HDL) cholesterol in the control subjects, but not in the diabetic subjects. In diabetic subjects with the genotype AA, the mean maximum intimal-medial thickness (IMT) of the carotid artery was significantly greater than in subjects with genotype AB or BB. PON may play an important role in the development of atherosclerosis associated with diabetes mellitus.

Aryldialkylphosphatase↗

PubMed1998

CT-guided biopsy of pulmonary nodules less than 3 cm: usefulness of the spring-operated core biopsy needle and frozen-section pathologic diagnosis.

OBJECTIVE: The purpose of this study was to improve the diagnostic accuracy of CT-guided biopsy of small lung nodules with the aid of frozen-section histopathologic diagnosis. SUBJECTS AND METHODS: Since 1993, we have evaluated 52 lung nodules smaller than 3 cm with CT-guided transthoracic biopsy. Thirty-five lesions were malignant and 17 were benign. Biopsy always started with a 20-gauge spring-operated core biopsy needle. Tissue samples were sent to the pathology laboratory immediately after biopsy for histopathologic diagnosis of the frozen sections. RESULTS: In 47 (90%) of 52 lesions, sufficient material for histologic diagnosis was obtained, including 34 (97%) of 35 malignant lesions and 13 (76%) of 17 benign lesions. In the 13 benign lesions for which histologic sampling was successful, a specific diagnosis of benign was made for 10 lesions (77%). In three cases, the sample was too small to make a histologic specimen, but cytologic study using the same sample led to the correct final diagnosis: one as malignant and two as benign. In the remaining two cases, biopsy was unsuccessful. The lesions were both 1 cm in size and were found to be benign on follow-up studies. CONCLUSION: CT-guided biopsy with the aid of frozen-section specimens using small-bore spring-operated core needles is a feasible technique with good results in the histologic diagnosis of small lung lesions.

Biopsy, Needle↗

PubMed1998

Percutaneous transhepatic lithotripsy using a choledochoscope: long-term follow-up in 14 patients.

OBJECTIVE: The purpose of our study was to estimate the long-term prognosis of patients with bile duct stones who undergo electrohydraulic lithotripsy guided by choledochoscopy. SUBJECTS AND METHODS: Since 1987, at our institution, 14 patients with bile duct stones have been treated using percutaneous electrohydraulic lithotripsy guided by choledochoscopy. The procedure was performed 5-7 days after biliary drainage using a 5-mm choledochoscope placed through an 18- to 20-French sheath. All patients underwent follow-up CT, sonography, or both every 6-12 months after treatment. RESULTS: No complications occurred in the 14 patients who underwent treatment. During a mean follow-up period of 4.8 years (range, 2-9 years), two (14%) of the 14 patients developed recurrent common bile duct stones, and another two (14%) developed recurrent small intrahepatic stones; all patients remained asymptomatic. CONCLUSION: Percutaneous electrohydraulic lithotripsy can be safely performed using a 5-mm choledochoscope. Recurrent calculi may be seen in 28% of patients.

Aged↗

PubMed1998

Mobilized plasma lead as an index of lead body burden and its relation to the heme-related indices.

Plasma lead (Pb-P) from workers were distributed in two main fractions: a protein bound fraction and low molecular weight fractions. Lead mobilized into plasma by CaEDTA was mainly observed in the low molecular weight fraction corresponding to lead disodium ethylenediamine tetraacetic acid (PbEDTA). The peak levels of Pb-P was attained around 1.5 and 2.5 hours after the start of CaEDTA injection. Pb-P and blood lead levels (Pb-B) at 2 h after the injection were 4.26 (+/- 2.84) and 0.96 (+/- 0.27) fold of the initial levels just before the injection. Pb-P concentrations at 2 hours after the start of CaEDTA injection (MPb-P) were well correlated (r = 0.740) with amounts of lead excreted in urine for 24 h thereafter (MPb-U). log MPb-P as well as log MPb-U were correlated with Pb-B (r = 0.765 and 0.817, respectively). Correlation coefficients of lead body burden (MPb-P or MPb-U) vs the logarithms of the effect indices (delta-aminolevulinic acid (ALA) dehydratase, ALA in urine, coproporphyrin in urine, and erythrocyte zinc protoporphyrin) were higher than the correlation coefficients of exposure indices (Pb-B or Pb-U) vs the logarithms of the effect indices. Thus the biological effect monitoring is significant and reliable for evaluating the functional components of lead body burden (MPb-P or MPb-U).

Adult↗

PubMed1998

Pancreatic exocrine function in patients with chronic liver disease.

It is unclear whether patients with chronic liver disease have impaired pancreatic exocrine function. This study was designed to answer this question. Pancreatic exocrine function was evaluated with pancreatic function diagnostic (PFD) test in 16 patients with chronic hepatitis, 32 patients with liver cirrhosis, and 26 patients with cirrhosis and hepatocellular carcinoma (HCC) and in 26 control subjects. The values of PFD test were significantly lower in both patients with liver cirrhosis (70.5 +/- 10.7%, P < 0.01) and patients with cirrhosis and HCC (68.5 +/- 11.2%, P < 0.01) than in controls (77.8 +/- 6.5%). Although the value was also lower in patients with chronic hepatitis (71.8 +/- 11.4%) than in that in controls, the difference did not reach the level of significance. To evaluate potential effect of the impairment of para-amino-benzoic acid (PABA) absorption on the results of PFD test, we further performed a PABA absorption test in 16 patients with chronic liver disease who had abnormal PFD tests. There were no significant differences of the values of PABA test between control group and any patients groups. These results suggest that patients with chronic liver disease have an abnormal pancreatic exocrine function.

Adult↗

PubMed1998

MRI evaluation of steroid- or alcohol-related osteonecrosis of the femoral condyle.

We reviewed 30 patients (46 knees) with steroid- or alcohol-related osteonecrosis of the femoral condyle. Their average age was 35 (14-61) years and the mean observation time was 7 (3-16) years. The medio-lateral extent and the anterior-posterior (AP) location of the necrotic lesion were evaluated on T1-weighted MRI and related to the collapse of the condyle. The size of the lesion was classified into three categories on the mid-coronal MRI of the femoral condyle: there were 44 small, 20 medium, and 9 large lesions. The condyle was divided into 3 zones: anterior, middle, and posterior. The location of the lesion was evaluated on the mid-sagittal image. There were 7 anterior, 9 middle, 29 posterior, 14 middle and posterior and, in 14 cases, all 3 zones were involved. 44 small lesions did not collapse, while 6/20 medium lesions and 5/9 large lesions collapsed. No lesion involving only one zone collapsed, while 4/14 lesions involving the middle and posterior zones and 7/14 lesions involving all three zones progressed to collapse. 4/6 condyles with large necrotic lesions involving all three zones collapsed. We conclude that the extent of the necrotic lesion on both the mid-coronal and mid-sagittal planes is of importance for the prognosis of osteonecrosis of the femoral condyle.

Adolescent↗

PubMed1998

Saccharides as osmotic agents in peritoneal dialysate: determination of molecular weight essential for more efficient fluid removal.

Glucose has widely been used as an osmotic agent in continuous ambulatory peritoneal dialysis (CAPD) but owing to its low molecular weight (MW), ultrafiltration (UF) in a 6-hour dialysate exchange does not appear sufficient. Thus, in the present study, a search was made to find saccharides that would ensure optimal UF, exceeding that obtained with glucose in a 6-hour dwell period. Rats were intraperitoneally infused with peritoneal dialysate (20 mL/body) containing the same molar concentrations (75.5 mM, 126 mM, or 204 mM) of various osmotic agents including glucose (monosaccharide, MW = 180.16) at concentrations of 1.36%, 2.27%, and 3.86%; maltose (disaccharide, MW = 342.30) at concentrations of 2.58% and 4.32%; maltotriose (trisaccharide, MW = 504.44), at concentrations of 3.81% and 6.36%; and maltopentaose (pentasaccharide, MW = 828.72) at concentrations of 6.26% and 10.4%. Intraperitoneal-fluid volume was measured at 1, 2, 3, 4, and 6 hours. With glucose as the osmotic agent, maximal UF was noted at 2 to 4 hours. UF was more efficient at 6 hours with maltotriose or maltopentaose as the osmotic agent. Even with a trisaccharide or pentasaccharide (molecular weights of 500 to 830), UF at 6 hours was found more efficient, as evidenced by the delay in peritoneal absorption. Fluid removal in 6 hours should be greater when using a dialysate containing oligosaccharides such as maltotriose or maltopentaose in place of glucose.

Animals↗

PubMed1998

Can recovered protein from the CAPD patient's own dialysis effluent substitute for dextrose?

Albumin has been evaluated as an osmotic agent for peritoneal dialysis as being physiologically safe and having modest colloidal osmotic pressure. However its extremely high cost inhibits clinical applications, and hypoalbuminemia is often seen in continuous ambulatory peritoneal dialysis (CAPD) patients, especially those with high peritoneal equilibration test (PET) values and who lose a large quantity of albumin everyday. This study aims at recovering protein from CAPD effluent and reusing it safely at reasonable cost as a substitute for dextrose. The dialysis effluent was collected and concentrated with a semipermeable membrane. Uremic toxins and low-molecular-weight solutes were removed by repeated filtration and water dilution. The concentrate was acidified with hydrochloric acid down to pH 2, thence de-acidified with water dialysis up to pH 5. At this point, the isoelectric point of albumin, at which precipitate was deposited, the precipitate was separated from the supernatant and re-dissolved into electrolyte solution. The acidified concentrate exhaled an unpleasant odor, like that of decayed food. The precipitate solution, however, did not smell at all. The initial ultrafiltration rate of the recovered protein solution was measured and compared with that of dextrose and dextran by using a high-sensitivity differential manometer, one end of which was connected with the test solution cell, and the other with the serum cell. The ends were separated by a semipermeable membrane. The recovered protein solution at 20 g/dL concentration was almost equivalent in initial ultrafiltration rate to the 2.0 g/dL dextrose solution and to 20 g/dL dextran (MW: 75,000 dalton) solution.

Albumins↗

PubMed1998

In vitro and in vivo generation and kinetics of glycosylation products in peritoneal dialysis effluents.

There are indications that advanced glycosylation end-products (AGEs) may affect in some manner the functions of the peritoneum. Only a few reports discuss the actual generation of glycosylated proteins and the intraperitoneal kinetics involved during continuous ambulatory peritoneal dialysis (CAPD). To demonstrate the formation of AGEs and their time-courses in peritoneal dialysis (PD) effluents, measurements were made of furosine, carboxymethyl lysine (CML), and pentosidine as glycosylation markers in vitro and in vivo using PD effluents obtained every 2 hours for up to 8 hours from 3 nondiabetic CAPD patients. Furosine and CML were found to be generated relatively early (within 6 hours), and their de novo formation was markedly enhanced subsequent to glucose addition. Furosine and CML production increased in proportion to glucose concentration. Pentosidine production did not change with time for up to 24 hours, and was not induced by glucose during this period. Carboxymethyl lysine production appeared to be suppressed in vitro with the addition of serum protein. Furosine in the intraperitoneal dialysate was initially the same as that in the plasma, but increased to twice as much in just 2 hours in vivo. Production of CML increased, but apparently was suppressed with leakage of plasma protein into the dialysate; this possibly may have been due to dilutional or antiglycation effects in the plasma. No stimulation of pentosidine production could be detected in the intraperitoneal dialysate even at 8 hours. The initiation of glycosylation of peritoneal proteins, with generation of furosine and CML but not pentosidine, is clearly shown by the present results to occur relatively early in the intraperitoneal dialysate, i.e., within a matter of hours.

Adult↗

PubMed1998

An epitope localized in c-Src negative regulatory domain is a potential marker in early stage of colonic neoplasms.

In previous work, we established a new monoclonal antibody that specifically recognizes the active form of c-Src tyrosine kinase (Kawakatsu et al, 1996). To determine whether c-Src is active in colorectal tumorigenesis, we examined the expression of an active form of c-Src in human normal mucosa, hyperplastic polyps, adenomas, and adenocarcinomas. The tissue distribution of the active form of c-Src was studied by immunohistochemistry using this antibody, termed Clone 28. Among 66 cases of adenoma tested, 61 (92%) showed positive staining (adenoma with mild atypia, 3 of 3; adenoma with moderate atypia, 38 of 42; adenoma with severe atypia, 20 of 21). In contrast to the frequent and intense staining in adenomas, adenocarcinoma showed weak staining with less frequency in 4 of 16 (25%) cases. The number of specimens with positive staining in well- and moderately differentiated adenocarcinomas was limited to an early stage. The active form of c-Src mainly localized to the nuclear membrane and the perinuclear region. These results provide the first direct evidence that the activation of c-Src appears to be an early event in colonic carcinogenesis in situ. The findings of the present study thus allow us to propose a molecular mechanism involving c-Src activation in the process of malignant transformation of the human colonic neoplastic cells.

Antibodies, Monoclonal↗

PubMed1998

Spontaneous retrograde dissection of the entire thoracic aorta originating in the abdominal aorta. Case report and review of the literature.

Spontaneous retrograde thoracic extension of the abdominal aortic dissection is extremely rare and difficult to manage. Only five cases have been previously reported in the English literature (dissection reaching the ascending aorta in four, dissection limited in the descending thoracic aorta in one), and all the cases of dissection which reached the ascending aorta were lethal. We herein report one case of a 37-year-old man who was operated on for spontaneous retrograde dissection of the entire thoracic aorta originating in the suprarenal abdominal aorta. Preoperative aortogram revealed the site of the intimal tear just above the celiac artery. He urgently underwent graft replacement of the descending thoracic aorta and the abdominal aorta with reimplantation of the thoracoabdominal visceral arteries. Although the patient had to undergo the second operation for the dissection of the remaining thoracic aorta four months postoperatively, he has been doing well 18 months after the second operation.

Adult↗

PubMed1998

[Pharmacokinetics of propofol and ketamine during and after total intravenous anesthesia with propofol, fentanyl and ketamine for pediatric patients].

Pharmacokinetics of propofol and ketamine during propofol-fentanyl-ketamine (PFK) anesthesia for pediatric surgery was studied. Plasma levels of propofol (Pp) were maintained approximately at 2.5 micrograms.ml-1 during surgery. Fifteen minutes after the cessation of propofol infusion, Pp decreased to 1.5 micrograms.ml-1. Plasma levels of ketamine (Pk) were maintained at 150-200 ng.ml-1 during the surgery. After the cessation of ketamine infusion, Pk decreased as quickly as Pp. Pk values at 15 minutes and 120 minutes after the cessation of the infusion were 93 ng.ml-1, 24 ng.ml-1, respectively. On the other hand, plasma norketamine (Pn) levels increased gradually during surgery and stayed at 100-150 ng.ml-1 after the end of ketamine infusion to play an important role in post-operative sedation and pain relief. In conclusion, pharmacokinetics of propofol and ketamine in pediatric patients was similar to that in adult patients. PFK anesthesia can be used safely for pediatric as well as for adult patients.

Anesthesia, Intravenous↗

PubMed1998

[Clinical indication of propofol for pediatric patients--pharmacokinetics of propofol and ketamine during and after total intravenous anesthesia with propofol, fentanyl and ketamine (PFK) in a neonate].

A 60-day-old neonate boy received hepatic portojejunostomy for biliary atresia under PFK. Pharmacokinetics of propofol and ketamine during and after PFK was also studied. Plasma levels of propofol (Cp) and ketamine (Ck) were maintained at 2 to 3 micrograms ml-1 and at 200 to 300 ng ml-1 during surgery, respectively. Both Cp and Ck decreased quickly after the end of infusions. From the pharmacokinetic point of view, PFK may be safely applied even for neonates.

Anesthesia, Intravenous↗

PubMed1998

Cell therapy to repair broken hearts.

Current therapeutic options for myocardial infarction include medical therapy, of proven but limited benefit, and various surgical options, which have either restricted applicability or unproven benefit. New cellular-based therapeutic strategies are being developed in response to the shortcomings of available treatments. These include attempts to reinitiate cardiomyocyte proliferation in the adult, conversion of fibroblasts to contractile myocytes and transplantation of myocytes into injured myocardium. The development and current status of these techniques and their relative advantages, problems remaining to be solved and potential clinical applications are reviewed.

Adult↗

PubMed1998

[A novel approach for cancer chemoprevention referred to as "gene-regulating chemoprevention"].

We examined the effect of butyrate on the expression of WAF1, a potent inhibitor of cyclin-dependent kinases, and its relation to growth arrest in a p53-mutated human colon cancer cell line WiDr. Five millimolar butyrate completely inhibited the growth of WiDr and caused G1-phase arrest. WAF1 mRNA was rapidly induced by treatment with 5.0 mM butyrate, and significant WAF1 protein induction was detected. Using several mutant WAF1 promoter fragments, we found that the butyrate responsive elements are specific Sp1 sites. These findings suggest that butyrate arrests the growth of WiDr by activating the WAF1 promoter through specific Sp1 sites in a p53-independent fashion. Based on our results, we propose a novel approach for cancer chemoprevention, which we term "gene-regulating chemoprevention". Our strategy is to activate the potent function of growth-inhibitory genes, which are preserved in cancer cells. WAF1 is a good candidate, because it rarely appears to be mutated in common human tumors, while the p53 gene is frequently mutated. Therefore the p53-independent activation of WAF1 by butyrate could be applied to the prevention of cancer when p53 is mutated.

Butyrates↗