Biomedical subjects

N Sato

Publications and source records attributed to N Sato.

At least 505 records · Page 28Linked to original sources

PubMed1998

Agenesis of the right lobe of the liver: report of a case.

A case of congenital agenesis of the right lobe of the liver detected in a patient with gastric cancer is reported. The diagnosis of this rare anatomical variant was established by a combination of computed tomography, abdominal angiography, and operative findings. The importance of accurately recognizing this condition is stressed, and the clinical presentation, radiographic appearance, and differential diagnosis are also discussed.

Aged↗

PubMed1998

Differential Ca2+ signaling in neonatal and adult rat hepatocyte doublets.

BACKGROUND/AIMS: Intracellular Ca2+ ([Ca2+]i) is important in various cellular functions, including cellular proliferation and differentiation. To elucidate the relationship between [Ca2+]i oscillations and physiological hepatocyte proliferation, phenylephrine-evoked [Ca2+]i responses were sequentially investigated using short-term cultured hepatocyte doublets obtained from 1-, 3-, 6- and 8-week-old rats. METHODS/RESULTS: DNA synthesis in hepatocytes, determined by BrdU incorporation, was approximately 20% in 1-week-old rats, and decreased to <1% as the rats aged. Correspondingly, [Ca2+]i responses evoked by 10 micromol/l phenylephrine in hepatocyte doublets shifted from transient to sinusoidal-type [Ca2+]i oscillations and then to a sustained increase in [Ca2+]i, followed by a gradual return to baseline. The incidence of [Ca2+]i oscillations was 100+/-0.0%, 83.3+/-16.7%, 38.7+/-0.6% and 5.5+/-5.0% in 1-, 3-, 6- and 8-week-old rats, respectively. Removal of extracellular Ca2+ did not abolish [Ca2+]i oscillations, indicating that [Ca2+]i oscillations were caused primarily by Ca2+ mobilization from internal sites of the cells. The [Ca2+]i level in each of the adjacent cells was synchronous in sustained increase in [Ca2+]i, but asynchronous in [Ca2+]i oscillations. In proliferating doublets obtained from 1-week-old rats, the frequency of oscillations increased in a dose-dependent manner for phenylephrine concentrations of 1 to 100 micromol/l. CONCLUSIONS: Phenylephrine-evoked [Ca2+]i oscillations were directly related to hepatocyte proliferation and were mediated by frequency modulation. These results suggest that phenylephrine-evoked [Ca2+]i oscillations may contribute to cell-cycle progression of hepatocytes in physiological liver growth.

Animals↗

PubMed1998

Changes in pancreatic function after pancreatoduodenectomy.

BACKGROUND: The objective of this study was to compare the alterations in pancreatic function after pancreatoduodenectomy between malignant and benign diseases. METHODS: In 34 patients who underwent pancreatoduodenectomy for pariampullary cancer (malignant group; n = 18) and benign pancreatic disorders (benign group; n = 16), exocrine and endocrine functions were analyzed before surgery, at a short-term period (< or = 2 months), and at a long-term period (>12 months) after surgery. Assessment was based on the BT-PABA excretion test, fasting blood sugar level, and oral glucose tolerance test. RESULTS: Compared with the preoperative level, urinary PABA excretion rate in the malignant group significantly decreased on short-term follow-up but recovered on long-term follow-up. However, that in the benign group increased on long-term follow-up without showing a short-term decline. Diabetes mellitus was present in 11 (61%) of the 18 patients in the malignant group and 6 (38%) of the 16 in the benign group before surgery. Glucose tolerance improved in 6 (55%) of the 11 patients in the malignant group but in only 1 (17%) of the 6 in the benign group shortly after surgery. In the benign group, 3 (30%) of 10 patients with normal preoperative glucose tolerance became diabetic after surgery, while no patient in the malignant group developed diabetes on short-term follow-up. CONCLUSIONS: Surgeons should pay attention to exocrine pancreatic function in patients with a periampullary cancer and to glucose metabolism in patients with benign disease over the short-term period after pancreatoduodenectomy.

4-Aminobenzoic Acid↗

PubMed1998

Duct-parenchymal ratio predicts exocrine pancreatic function after pancreatoduodenectomy and distal pancreatectomy.

BACKGROUND: The postoperative exocrine pancreatic function was compared between pancreatoduodenectomy and distal pancreatectomy, and we studied the relationship between the preoperative morphology of the pancreas expected to remain and pancreatic function after surgery. PATIENTS AND METHODS: In 27 patients who underwent pylorus-preserving pancreatoduodenectomy (PPPD group) and 12 who underwent distal pancreatectomy (DP group), the exocrine pancreatic function was assessed using the BT-PABA excretion test before surgery and short term after surgery (< or =2 months). Preoperative morphology of the pancreas at a presumed line of transection was also investigated on computed tomography. RESULTS: The mean urinary PABA excretion rate in the PPPD group decreased from 68.3% to 53.7% (P = 0.0029), whereas that in the DP group showed no significant change (70.7% versus 72.7%). The mean size of the main pancreatic duct at the presumed transection line in the PPPD group was significantly greater than that in the DP group (6.5 mm versus 2.6 mm, P = 0.0002). The mean parenchymal thickness of the pancreatic gland at the presumed transection line in the PPPD group was significantly smaller than that in the DP group (16.1 mm versus 18.6 mm, P = 0.04). The mean ratio of the pancreatic duct caliber to parenchymal thickness (duct-parenchymal ratio) in the PPPD group was significantly higher than that in the DP group (0.43 versus 0.14, P = 0.0004). There was a significant negative correlation between the postoperative PABA excretion rate and the duct-parenchymal ratio (P = 0.0057). CONCLUSIONS: The postoperative exocrine pancreatic function after PPPD and DP was significantly influenced by the morphology of the pancreas at the presumed transection line. It is important to evaluate the preoperative morphology of the presumably remaining pancreas, especially duct-parenchymal ratio, to predict the exocrine pancreatic function short term after pancreatectomy.

Adult↗

PubMed1998

Marginal irregularity of flat elevated type of colorectal tumor as a marker of malignant potential.

BACKGROUND: The malignant potential of superficial elevated type tumors is still controversial. Because biopsy specimens alone are sometimes not sufficient for diagnosis due to histologic heterogeneity within the tumor, other clinical parameters for evaluation of the degree of malignancy would be helpful. METHODS: A new morphometric parameter, the "F-circle," which represents the irregularity of the tumor margin, was studied in 115 endoscopically recognized superficial, flat, elevated type colorectal tumors without a central depressed area with respect to histologic evaluation of the degree of malignancy. RESULTS: The mean F-circle values of adenomatous lesions with mild or moderate atypia, severe atypia, and adenocarcinoma were 0.709+/-0.115, 0.619+/-0.149, and 0.536+/-0.133, respectively. CONCLUSION: The superficial elevated type of colorectal tumor having more marginal irregularity had a greater malignant potential, and the F-circle may be a useful clinical parameter for evaluation of the degree of malignancy.

Adenocarcinoma↗

PubMed1998

Power spectral analysis of heart rate variability in type A females during a psychomotor task.

This study investigated changes in autonomic nervous activities due to psychological stress in Type A females. Eight Type A and eight Type B females performed a psychomotor task for 30 minutes. Power spectral analysis of heart rate variability (HRV) was used to examine the autonomic nervous activities. Results showed the low frequency (LF) component and LF/HF ratio in Type A females increased after the onset of the task. There were no significant differences in task performance between Type A and Type B females. The subjective mental workload increased gradually in Type A females during the tasks, whereas in Type B females this parameter did not change in a consistent manner. The results suggest that the sympathetic nervous system in Type A females was more stimulated by the task and Type A females felt a greater subjective mental workload than did Type B females.

Adult↗

PubMed1998

Isotonic ethanol inhibits the generation of superoxide anion in neutrophils by inducing cell expansion.

The effects of ethanol on the production of oxygen-derived free radicals by neutrophils are controversial. Osmolarity-mediated alteration of cell volume appears to be an important mechanism for regulating neutrophil activity. We investigated in neutrophils from healthy volunteers the effect of isotonic/hypertonic ethanol on both chemiluminescence amplified by a Cypridina luciferin analog in response to N-formyl-Met-Lue-Phe and cell volume measured with a Coulter counter. Both isotonic and hypertonic ethanol significantly decreased chemiluminescence in a dose-dependent manner. Isotonic ethanol produced a greater magnitude of inhibition than hypertonic ethanol (P<0.01). Another permeable molecule, urea, and hypotonic solution had the same effects on chemiluminescence. Isotonic and hypertonic ethanol caused a prompt cell expansion and shrinking, respectively. On the other hand, isotonic sucrose, an impermeable molecule, was ineffective in both chemiluminescence and cell volume changes. These data suggest that isotonic ethanol inhibits the superoxide anion production by inducing cell expansion probably due to increased intracellular osmotic pressure caused by rapid ethanol permeation through the plasmalemma. This impaired neutrophil function may, in some part, contribute to the susceptibility to infection in alcoholics.

Cell Size↗

PubMed1998

Nucleotide sequence analysis of a human monoclonal antibody 22-13 reactive with lung tumor-associated antigen.

A human monoclonal antibody (HuMAb) 22-13 (IgG1, kappa) recognizes a cytoplasmic antigen associated primarily with human lung tumors. This study reports the primary nucleotide and deduced amino acid sequences of the rearranged heavy and light chains of the HuMAb 22-13. This HuMAb uses a VH gene member of the V(H)Ia gene family, 51P1 and is productively rearranged with a D-D fusion product of the D(LR)2 and D(XP)2 germ line DH genes and the germ line JH3 gene. HuMAb 22-13 Vkappa belongs to the kappa light chain variable subgroup IIIb family and appears to be derived from the Humkv325 germ line gene and is rearranged with a germ line Jkappa5 gene. The results reveal that production of a HuMAb 22-13 is achieved by rearrangement of the 51P1/Humkv325 germ line variable region gene combination, associated with the autoimmune repertoire and that HuMAb 22-13 has a striking sequence homology to rheumatoid factors (RFs) of the Wa idiotypic family. HuMAb 22-13 and Wa RFs have in common V(H)Ia and VkappaIIIb gene segments, but use different DH, JH and Jkappa gene segments. However, in spite of this structural similarity, HuMAb 22-13 does not display rheumatoid factor activity. Taken together with the reported findings, these data indicate the representation of the shared usage of highly homologous variable region genes in entirely different humoral immune responses in the human system.

Amino Acid Sequence↗

PubMed1998

Accumulation of IL-12-activated antitumor effector cells into lymph nodes of tumor-bearing mice.

Simultaneous administration of high dose of IL-12 into tumor-inoculated mice resulted in a marked reduction of tumor growth in parallel with the augmented generation of cytotoxic T-cells, natural killer (NK) cells and IFN-gamma-producing Th cells. We found that these IL-12-activated antitumor effector cells preferentially accumulated in peripheral lymph nodes concomitantly with lymphadenopathy. However, IL-12 rather induced disappearance of antitumor effector cells including CD4+ T, CD8+ T and NK cells from spleen in spite of inducing splenomegaly. Lymph node cells obtained from IL-12-treated B16F0-bearing mice showed a marked IFN-gamma production in response to not only IL-2, IL-12, anti CD3 mAb but also B16F0 melanoma cells. Moreover, they could lyse B16F0 melanoma cells in a long-term cytotoxicity assay. It was also confirmed that IL-12-activated IFN-gamma producing Th1 cells were accumulated in tumor local site. Thus, IL-12 appeared to have a capability of stimulating selective migration of antitumor cells into lymph nodes and tumor local sites.

Animals↗

PubMed1998

Audiological assessment before and after fractionated stereotactic irradiation for vestibular schwannoma.

PURPOSE: To find the audiological outcome after LINAC-based fractionated stereotactic irradiation (STI). MATERIALS AND METHODS: Twenty-four patients with vestibular schwannoma treated by fractionated STI between 1991 and 1997 had measurable hearing before STI and were followed audiologically for more than 6 months. The pure tone average (PTA) was measured by averaging the air-conduction threshold for five main frequencies (250-4000 Hz) before and periodically after STI in the 24 patients. Several possible prognostic factors for hearing preservation (defined as a PTA change at the last follow-up of less than 10 dB) were investigated. The median follow-up time was 22 months, ranging from 5 to 69 months. The irradiation schedule was 36 Gy in 20 fractions in 5 weeks to 44 Gy in 22 fractions in 6 weeks followed by 4 Gy/1 fraction boost. RESULTS: The pure tone average before STI was distributed from 7 to 73 dB. Fifty percent of patients showed a change in PTA of less than 10 dB, 79.2% of patients showed a change in PTA of less than 20 dB and 20.8% of patients showed a change in PTA of more than 21 dB at the last follow-up. Only one patient (4%) became deaf. Cases with a sudden loss of hearing were more likely to experience hearing preservation than those with gradual loss of hearing (P<0.05). The mean age was younger in patients whose hearing was preserved (P<0.05). Poor pretreatment PTA appeared to linearly correspond to the changes in PTA (regression coefficient 0.78). The size of the tumor was not related to the change in PTA. No relationship was observed between the maximum or peripheral dose and the PTA change. The real benefit of stereotactic boost after small-field fractionated irradiation was not certain. CONCLUSION: Fractionated STI produced a hearing preservation rate compatible with meticulously collimated multi-spots single fraction irradiation. Further follow-up is required to confirm the long-term benefits of fractionation.

Audiometry↗

PubMed1998

Axonal transports of Boc-Gly-Arg-Arg-MCA hydrolysing enzyme in rat sciatic nerves.

Study on neural axon transport is a very useful method to find a neuron-specific protease. In the present study, the enzyme activity (release of 7-amino-4-methyl-coumarin from t-butyloxycarbonyl-glycyl-L-arginyl-L-arginine-4-methylcoumaryl-7-amide) was measured in the proximal, middle, and distal segments between 12 and 120 h after double ligations of rat sciatic nerves to find precursor processing enzyme specific for pair of basic amino acid residue. The enzyme activity was significantly increased not only in the proximal but also in the distal segments 12-120 h after the ligation, and the maximal enzyme activity was found in both segments at 72 h. The enzyme activity eluted by anion exchange chromatography of the proximal segment showed at least three peaks, and was slightly higher than the activity of the distal one. The activity in the middle segment was very low in comparison with the activity in the proximal and distal segments. These data indicate that some of the enzymes specific for pair of basic amino acid residue are transported by both anterograde and retrograde axonal flow, and may undergo a neuron-specific processing.

Amino Acid Sequence↗

PubMed1998

Malignant mesenchymoma arising in an incisional scar of the abdominal wall.

A case of malignant mesenchymoma of the anterior abdominal wall, composed of leiomyosarcoma, chondrosarcoma and osteosarcoma is described. The tumour, arising in the old scar of a previous operation, was completely removed surgically. Eleven months after the operation the patient is well with no evidence of recurrence. There have been no previous reports of malignant mesenchymoma developing in operation scars. We believe that this traumatic factor played a significant role in the aetiology of this rare soft-tissue neoplasm.

Abdominal Muscles↗

PubMed1998

Angiotensin II type 1 receptor gene polymorphism is associated with increase of left ventricular mass but not with hypertension.

A genetic epidemiologic approach is useful to elucidate the genes responsible for hypertension. Genetic analyses of the components of the renin-angiotensin system have succeeded in showing an association between their polymorphism and hypertension. Recently, two types of angiotensin II receptor were cloned and characterized. To examine the genetic contribution of angiotensin II type 1 receptor (AT1) and type 2 receptor (AT2) genes in human essential hypertension, a case-control study was performed in Japanese subjects. The study comprised 321 subjects with hypertension who satisfied the criteria for essential hypertension, together with 215 age and sex matched controls. The significance of the differences in genotype distribution between hypertensive and normotensive subjects was examined by chi2 analysis. Neither AT1 nor AT2 gene variants were associated with human essential hypertension in the Japanese subjects. However, the AT1 receptor gene polymorphism was associated with left ventricular mass index in normotensive subjects. The study results suggest that gene polymorphisms of both angiotensin II receptors are not directly involved in the increase of genetic risk for hypertension, but that the AT1 receptor gene might contribute genetically to the increase of left ventricular mass.

Aged↗

PubMed1998

No association between alpha-adducin 460 polymorphism and essential hypertension in a Japanese population.

Many unknown genetic factors are involved in the pathogenesis of hypertension. Recently, the reverse genetic approach revealed that some genetic variants, such as angiotensinogen, lipoprotein lipase, and alpha-adducin gene polymorphisms, increase the risk for hypertension. Both in rat and human, the genetic predisposition to hypertension was confirmed only for angiotensinogen and alpha-adducin genes. Adducin is a membrane cytoskeletal protein, which is thought to regulate sodium transport. Abnormalities of membrane sodium transport in the kidney play an important role in hypertension. A recent report by Cusi et al showed that the Trp allele of alpha-adducin polymorphism (Gly 460 Trp) is associated with an increased risk of hypertension in whites, which led us to carry out a case-control study to examine whether the same association is observed in the Japanese population. We recruited 170 hypertensive and 194 normotensive Japanese subjects and compared the genotype distribution of alpha-adducin 460 polymorphism between cases and controls and between whites and Japanese. Trp allele frequency of controls in the Japanese subjects was twice as high as in the whites. However, no association was observed between alpha-adducin polymorphism and hypertension. Furthermore, alpha-adducin 460 polymorphism was not associated with any clinical characteristics. Accordingly, we concluded that alpha-adducin 460 polymorphism is not a major genetic risk for hypertension in Japanese people.

Alleles↗

PubMed1998

Methylenetetrahydrofolate reductase gene polymorphism: relation to blood pressure and cerebrovascular disease.

Hyperhomocysteinemia is reported to be associated with an increase in the incidence of ischemic heart disease and cerebrovascular disease. Genetic aberrations in methylenetetrahydrofolate reductase (MTHFR) may account for reduced enzyme activity and elevated plasma homocysteine level. A recent report revealed that a common mutation (677C to T; Ala to Val) in the MTHFR gene is associated with decreased specific MTHFR activity and with increased risk for coronary artery disease in the homozygous state (Val/Val). In the present study, we investigated whether the MTHFR gene is a genetic risk factor for cerebrovascular disease (CVD). To undertake a case-control study, we selected the patients with cerebral infarction (n = 48) or cerebral hemorrhage (n = 35) and examined the association between MTHFR gene polymorphism and CVD. The genotype distribution of the MTHFR gene was not significantly different between cases and controls. Because the possibility of matching the morbidity of the effects of hypertension, the lack of association could not be excluded in the first study; however, we also examined whether the MTHFR mutation was associated with any clinical risk factor for CVD or with hypertension. It turned out that the subjects with the Val allele of the MTHFR gene had significantly lower blood pressure than the subjects with other genotypes in the general population (P = .02), and that the frequency of the Val/Val genotype in hypertensive subjects (n = 173) was significantly lower than in control subjects (n = 184) (P = .03). From these results, we conclude that the Val/Val homozygous state of the MTHFR gene increased the risk of thrombosis, but reduced the blood pressure, which resulted in the lack of increased risk for CVD.

Cerebrovascular Disorders↗

PubMed1998

Three-step tumor imaging with biotinylated monoclonal antibody, streptavidin and 111In-DTPA-biotin.

The purpose of this study was to test the three-step targeting of tumors in mice using biotinylated antibody, streptavidin and radiolabeled biotin. Nude mice bearing subcutaneous LS180 human colon cancer xenografts were intravenously administered with 200 microg of the biotinylated anti-Tn monoclonal antibody MLS128, and 2 days later they got intravenous injection of 50 microg of streptavidin. They were intravenously injected 1, 4 or 7 days later with 0.5 microg of 111In-diethylenetriamine pentaacetic acid (DTPA)-biotin. The tumor uptake, determined 2 h later, was 1.4, 0.5 and 0.6% injected dose/gram of tissue (ID/g), respectively, and the blood radioactivity was 1.0, 0.2 and 0.2% ID/g, respectively. When the interval between the streptavidin and radiolabeled biotin injections was prolonged from 1 day to 7 days, the tumor-to-blood ratio 2 h after injection of 111In-labeled biotin increased from 1.5 to 4.0. Clear tumor images were obtained as early as 2 h after injection of radiolabeled biotin. In conclusion, these preliminary data suggested that the three-step method using the streptavidin-biotin system would be applicable in an experimental mouse tumor model and provides images of tumors rapidly and clearly after injection of radiolabeled biotin.

Animals↗

PubMed1998

Effect of administration route and dose of streptavidin or biotin on the tumor uptake of radioactivity in intraperitoneal tumor with multistep targeting.

The effect of the administration route and dose of streptavidin or biotin on the biodistribution of radioactivity in multistep targeting was studied in nude mice bearing intraperitoneal (IP) colon cancer xenograft. The multistep targeting included a two-step method using biotinylated antibody and radiolabeled streptavidin and a three-step method with radiolabeled biotin based on the two-step method. A monoclonal antibody, MLS128, which recognizes Tn antigen on mucin, was biotinylated and injected intravenously (i.v.) or i.p. in nude mice bearing human colon cancer LS180 IP xenografts for pretargeting. In the two-step method, i.p.-injected streptavidin showed a higher tumor uptake and tumor-to-nontumor ratios than i.v.-injected streptavidin regardless of administration route of pretargeting. The tumor uptake of radiolabeled streptavidin was increased with a high dose of biotinylated antibody pretargeting, but decreased with an increasing dose of streptavidin. In the three-step targeting, i.p. injection also gave a higher tumor uptake of radiolabeled biotin than i.v. injection. In conclusion, i.p. administration of radiolabeled streptavidin or biotin resulted in more efficient IP tumor targeting with the multistep methods.

Animals↗

PubMed1998

Differential diagnosis of cervical lymphadenopathy with intranodal color Doppler flow signals in patients with oral squamous cell carcinoma.

OBJECTIVE: The purpose of this study was to differentiate reactively enlarged cervical nodes from metastatic nodes by means of color Doppler flow imaging in patients with oral squamous cell carcinoma. STUDY DESIGN: Enlarged lymph nodes with long-axis diameters greater than 10 mm in 30 patients were classified into 4 groups according to color Doppler flow imaging findings. After the patients underwent neck dissection, the findings were correlated with the pathologic features. RESULTS: Color Doppler flow imaging detected 58 enlarged nodes with long-axis diameters greater than 10 mm. Thirty-five lymph nodes showed no color flow signals; of these, 32 (91%) were metastatic and 3 were reactive. Of the 12 lymph nodes with central color flow signals, 11 (92%) were reactively enlarged and 1 was metastatic. CONCLUSIONS: The presence of central signals on color Doppler flow imaging appeared to be a significant parameter associated with reactively enlarged benign nodes in patients with oral squamous cell carcinoma.

Blood Flow Velocity↗