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Biomedical subjects

S Nishida

Publications and source records attributed to S Nishida.

At least 181 records · Page 10Linked to original sources
PubMed1998

Mp colorectal cancer should be defined as early colorectal cancer.

Little is known about the clinicopathologic features of mp colorectal cancer, defined as a cancer where the depth of invasion is limited to within the mucosa, the submucosa and the proper muscle. This study was designed to determine the clinicopathologic features of mp colorectal cancers. From 1973 to 1993, 83 mp colorectal cancer and 66 sm colorectal cancer patients were treated in our department and were enrolled in this study. During the same period, 66 patients with sm colorectal cancer defined as a cancer where the depth of invasion is limited to within the mucosa and the submucosa, were treated. The clinicopathologic findings of these patients were determined retrospectively from their hospital records. Clinicopathologic differences in sm and mp colorectal cancers were compared with sm and mp gastric cancers. The incidence of mp colorectal cancer increased from 7.9% in 1973-1977 to 16.2% in 1988-1993. An advanced macroscopic appearance, a larger tumor size, lymph node metastasis and lymph vessel invasion were more predominant in mp than sm colorectal cancer. Multivariate analysis demonstrated that these clinicopathologic factors were not statistically independent prognostic factors for mp colorectal cancer patients. There was no statistical difference in postoperative survival between sm and mp colorectal cancer patients. Mp colorectal cancer should be defined as early colorectal cancer, because the postoperative survival rate does not differ between mp and sm colorectal cancers, and the clinicopathologic differences between these two are negligible.

Colorectal Neoplasms↗
PubMed1998

Purification and characterization of kaouthiagin, a von Willebrand factor-binding and -cleaving metalloproteinase from Naha kaouthia cobra venom.

A von Willebrand factor (vWF)-binding and -cleaving metalloproteinase, termed "kaouthiagin", was purified from the venom of cobra snake Naja kaouthia. Kaouthiagin is a monomer with a molecular mass of about 46 kDa and 51 kDa under non-reducing and reducing conditions, respectively, and the N-terminal amino acid sequence is homologous to high molecular mass snake venom metalloproteinases. Kaouthiagin bound to vWF in a divalent ion-independent manner, but the reduced kaouthiagin failed to interact with vWF, suggesting that the protein conformation maintained by intrachain-disulfide linkages of the molecule is essential for the binding to vWF. Neither botrocetin nor bitiscetin, vWF-binding modulators from another snake venom, interfered with the binding between kaouthiagin and vWF, but a monoclonal antibody VW92-3 specific to the N-terminal region of vWF (residues 1-910) inhibited the binding. Without affecting platelet GPIb/IX and GPIIb/IIIa, kaouthiagin specifically cleaved vWF between residues Pro-708 and Asp-709 in a divalent ion-dependent manner to diminish the multimeric structure of vWF in plasma, resulting in the loss of ristocetin-induced platelet aggregability and the collagen-binding activity of vWF. These results indicate that kaouthiagin is a unique metalloproteinase which specifically binds to and cleaves vWF at a specific site and that it will be a useful tool for functional dissection of vWF.

Amino Acid Sequence↗
PubMed1998

[A case of primary malignant lymphoma of the bladder].

The patient was a 34-year-old male. He visited a community hospital complaining of macroscopic hematuria and pollakiuria. Cystoscopic examination demonstrated a bladder tumor. Transurethral resection of the bladder tumor (TUR-Bt) was performed. Histological examination disclosed malignant lymphoma (non-Hodgkin's lymphoma, mixed type). The tumor was classified into the B cell type by the immunohistological staining with surface antigens. He was referred to St. Marianna University, School of Medicine for chemotherapy. Pelvic computed tomography (CT) after admission demonstrated a tumor with a wide pedicle located in the vesicle triangle extending to the posterolateral wall of the bladder. No abnormalities were found in other organs. After establishment of the diagnosis of primary bladder malignant lymphoma, 6 courses of chemotherapy (adriamycin, vincristine, cyclophosphamide, prednisolone, etoposide, methotrexate) were performed. The tumor disappeared completely on imaging studies after chemotherapy. Biopsy of the bladder disclosed no abnormal tissues. No evidence of recurrence or metastasis was found 5 years after chemotherapy.

Adult↗
PubMed1997

Induction of manganese superoxide dismutase by thyroid stimulating hormone in rat thyroid cells.

Alterations in the superoxide dismutase (SOD) content of thyroid tissues occurring in association with thyroid dysfunction have been reported. In this study, the Mn-SOD content was found to increase in thyroid tissues of rats administered thyroid stimulating hormone (TSH) and in thyrocytes cultured in medium supplemented with TSH. Furthermore, in the thyroid glands of rats whose serum TSH level was elevated by inhibiting the synthesis of T3 and T4 by 6-methyl-2-thiouracil, the Mn-SOD increased as the TSH concentration increased. In the cultured thyrocytes, the increase in Mn-SOD induced by TSH was inhibited by the C-kinase inhibitor H7. These findings suggest the induction of Mn-SOD by TSH in thyroid cells and point to a role of C-kinase in this process, thereby indicating that a close relationship exists between the serum TSH level and the change in Mn-SOD content in thyrocytes with thyroid dysfunction.

Animals↗
PubMed1997

Negative control of DNA replication by hydrolysis of ATP bound to DnaA protein, the initiator of chromosomal DNA replication in Escherichia coli.

DnaA protein, the initiation factor for chromosomal DNA replication in Escherichia coli, is activated by ATP. ATP bound to DnaA protein is slowly hydrolyzed to ADP, but the physiological role of ATP hydrolysis is unclear. We constructed, by site-directed mutagenesis, mutated DnaA protein with lower ATPase activity, and we examined its function in vitro and in vivo. The ATPase activity of purified mutated DnaA protein (Glu204-->Gln) decreased to one-third that of the wild-type DnaA protein. The mutation did not significantly affect the affinity of DnaA protein for ATP or ADP. The mutant dnaA gene showed lethality in wild-type cells but not in cells growing independently of the function of oriC. Induction of the mutated DnaA protein in wild-type cells caused an overinitiation of DNA replication. Our results lead to the thesis that the intrinsic ATPase activity of DnaA protein negatively regulates chromosomal DNA replication in E. coli cells.

Adenosine Diphosphate↗
PubMed1997

Expression of the JNK2-alpha1 gene in the developing chick brain.

We have isolated chicken JNK2-alpha1 encoding a c-Jun N-terminal kinase, and examined the expression during embryogenesis. The kinase domain sequence is well conserved between chicken and mammals, but carboxy-terminal sequence of JNK is divergent from subtype 1 and 2, possibly derived from alternative splicing. The JNK2-alpha1 gene is preferentially expressed in the neuroepithelium of developing brain at stages 16-26, and transcripts are not detectable in the other region including spinal cord. These results suggest that JNK2-alpha1 is involved in development of the central nervous system as a mediator of stress-activated protein kinase pathway conferring competence to the external stimuli such as growth factors.

Amino Acid Sequence↗
PubMed1997

Immotile phenotype of an Escherichia coli mutant lacking the histone-like protein HU.

The histone-like protein HU in Escherichia coli are encoded by the hupA and hupB genes. A hupA-hupB double deletion mutant has now been shown to express an immotile phenotype. The motility of hupA or hupB single mutants was similar to that of wild-type cells. SDS-polyacrylamide gel electrophoresis revealed that the amount of flagellin in the hupA-hupB double deletion mutant was markedly reduced compared with the wild-type strain suggesting that the immotile phenotype of the double deletion mutant is caused by a loss of flagella.

Bacterial Outer Membrane Proteins↗
PubMed1997

The operative indications for proximal gastrectomy in patients with gastric cancer in the upper third of the stomach.

While proximal gastrectomy is often performed for early gastric cancer in Japan, it remains unclear whether or not proximal gastrectomy should be performed for advanced gastric cancer. This study was designed to determine the operative indications for proximal gastrectomy in patients with gastric cancer in the upper third of the stomach. A total of 1691 patients with gastric cancer were reviewed retrospectively from hospital records during the period from 1969 to 1994, and the clinicopathologic characteristics of 82 patients who underwent proximal gastrectomy were compared with those of 150 patients who underwent total gastrectomy. Lymph node metastasis along the lower part of the stomach was observed in gastric cancers which had invaded beyond the muscularis propria of the stomach, but not in those confined to the muscularis propria. Three patients with gastric cancer that had invaded beyond the muscularis propria and metastasized to nodes along the lower part of the stomach were cured by total gastrectomy. However, there was no difference in the postoperative survival rates of the patients treated with proximal gastrectomy and those treated with total gastrectomy, irrespective of tumor stage and depth of invasion. Thus, proximal gastrectomy should be performed for gastric cancer when the depth of invasion is confined to the muscularis propria of the stomach.

Aged↗
PubMed1997

Simultaneous motion contrast across space: involvement of second-order motion?

A static or counterphase (target) grating surrounded by drifting (inducer) gratings is perceived to move in the direction opposite that of the inducers. We compared the relative magnitudes of these simultaneous motion contrasts generated by both first-order and second-order stimuli. The first-order stimuli were sinusoidal luminance-modulations of a uniform field, and the second-order stimuli were sinusoidal contrast-modulations of a random-dot field. When the target was a static grating, the second-order stimuli induced little motion contrast, while the first-order stimuli of the same effective contrast produced clear motion contrast. When the target was a counterphase grating, both first- and second-order stimuli produced clear motion contrast. These results are discussed in relation to the involvement of second-order motion pathways in the relative-motion processing, and the two types of motion aftereffects obtained with static and dynamic test stimuli.

Contrast Sensitivity↗
PubMed1997

Contrast dependencies of two types of motion aftereffect.

We examined the effects of adaptation and test contrasts on the duration of two types of motion aftereffect (MAE) that presumably reveal different levels of motion processing: MAE with a static test stimulus (static MAE), and that with a counterphasing test stimulus (flicker MAE). MAE duration increased with increasing adaptation contrast. When the test contrast was low, it increased rapidly, and saturated at a low adaptation contrast. When the test contrast was high, however, it gradually increased over a wide range of adaptation contrasts. These complex effects of stimulus contrasts could be well described by a dependency on adaptation contrast normalized by test contrast on a logarithmic axis. Little difference was found between the results for two types of MAE. The interaction between adaptation and test contrasts leads us to reject the idea that the shape of adaptation contrast dependency of MAE duration reflects that of the sensitivity function of motion detecting mechanisms. The results also suggest a functional similarity between the processes underlying static and flicker MAEs with regard to their responses to contrasts.

Adaptation, Physiological↗
PubMed1997

Linking lower and higher stages of motion processing?

The spatial frequency selectivity of motion detection mechanisms can be measured by comparing the magnitude of motion aftereffects (MAEs) as a function of the spatial frequency of the adapting and test gratings. For static test gratings, narrow spatial frequency tuning has been reported in a number of studies. However, for dynamic test patterns, reports have been conflicting. Ashida & Osaka [(1994). Perception, 23, 1313-1320] found no tuning whereas Bex et al. [(1996) Vision Research, 36, 2721-2727] reported a narrow tuning. The main difference between the two studies was the temporal frequency of the test pattern. In this study we measured the spatial frequency tuning of the MAE using test patterns for a range of temporal frequencies. The results confirmed that there was narrow spatial frequency tuning when the test pattern was counterphasing at a low temporal frequency. However, the spatial frequency selectivity broadened as the temporal frequency of the test pattern was increased.

Adaptation, Ocular↗
PubMed1997

Dual multiple-scale processing for motion in the human visual system.

A number of psychophysical and physiological studies have suggested that first- and second-order motion signals are processed, at least initially, by independent pathways, and that the two pathways both consist of multiple motion-detecting channels that are each narrowly tuned to a different spatial scale (spatial frequency). However, the precise number and nature of the mechanisms that subserve first- and second-order motion perception in human vision remain both controversial and speculative. We sought to clarify this issue by conducting selective adaptation experiments, in which modulation-depth thresholds for identifying the direction of stimulus motion of first-order (luminance-defined) and second-order (contrast-defined) drifting gratings were measured both prior to and following adaptation to motion. The drift direction, spatial frequency and stimulus type (either first- or second-order) of the adaptation and test stimuli were systematically manipulated. When the adaptation and test stimuli were either both first-order gratings or both second-order gratings, robust elevations of direction-identification thresholds were found and, importantly, these aftereffects exhibited both direction-selectivity and spatial-frequency selectivity. Cross-over-adaptation effects between first- and second-order gratings were also sometimes observed, but were very weak and not spatial-frequency selective. These findings give direct support for the existence of multiple-scale processing for first- and second-order motion in the human visual system and provide additional evidence that the two varieties of motion are initially processed by independent pathways.

Adaptation, Ocular↗
PubMed1997

Estimate of physiological variability of peak latency in single sweep P300.

Among single sweep records of event-related potentials (ERPs), the peak latency of P300, which is one of the most prominent positive peaks in the ERP obtained in the oddball paradigm, may vary depending on the conditions of the subject. In the analysis of characteristics of the variability in the peak latency, it is important to know to what extent the variability of the measured peak latency (measured variability) is actually caused by physiological factors (physiological variability). In our previous study, a method was developed for judging whether the physiological variability really exists or not, and if it does exist, the developed method extracts the physiological variability from the measured variability based on a limited number of single sweep records. In the present study, based on the P300 waveforms which were detected by blinded visual inspection of the ERP data obtained by an auditory oddball paradigm from 12 healthy adults, the physiological variability was shown to exist with a confidence level of 95% for all subjects. Furthermore, its interval estimate was calculated by subtracting noise variability from the measured variability with a confidence level of 80%, and it was found to range from 17 to 57 ms for all subjects.

Adult↗
PubMed1997

Early gastric cancer mimicking advanced gastric cancer.

The clinicopathological features of 37 early gastric cancers mimicking advanced gastric cancer were reviewed retrospectively, and were compared with 596 other early gastric cancers and 126 mp gastric cancers, defined as gastric cancer invading the muscularis propria of the stomach. A greater tumour size (P < 0.005), submucosal invasion (P < 0.005), lymph node and lymph vessel invasion (P < 0.005) and vascular invasion (P < 0.025) were found more frequently in early gastric cancers mimicking advanced gastric cancers than in other early gastric cancers. There were no significant differences in the clinicopathological findings between early gastric cancers mimicking advanced gastric cancers and mp gastric cancers. Patients with early gastric cancers mimicking advanced gastric cancers showed a lower survival rate than patients with other early gastric cancers, but a higher survival than those with mp gastric cancers. The macroscopic appearance of an advanced gastric cancer was an indicator of massive submucosal invasion and lymph node metastasis in early gastric cancer. As early gastric cancers mimicking advanced gastric cancers showed similar clinicopathological findings to mp gastric cancers, these cancers should be treated as mp gastric cancers.

Female↗
PubMed1997

Bone density and bone metabolic markers in active collegiate athletes: findings in long-distance runners, judoists, and swimmers.

We investigated the bone metabolic system status of 103 male and female volunteer collegiate athletes, who were actively pursuing one of three different sports: Long-distance running (LR); judo (JU); and swimming (SW). The following parameters were evaluated: total body bone mineral density (TMBD); bone-forming metabolic markers; serum procollagen type I C-peptide (PICP) levels; bone alkaline phosphatase (B-ALP) content; bone resorption markers, urinary pyridinoline (Pyd) and deoxypyridinoline (Dpd) levels. We found that the TBMD and urinary Dpd values in JU athletes were significantly higher (p < 0.001) than in athletes of the same sex in the other two groups. The urinary Pyd level in male JU athletes was also higher (p < 0.001) than that in the other two groups, but that in females JU athletes was only higher (p < 0.01) than that in female LR athletes. The PICP levels were similar to the TBMD values in all groups. No differences in bone density or in bone metabolic markers were seen in LR and SW athletes of the same sex. We thus conclude that differences in bone mineral density are in part due to the demands of the specific sport, and that they are reflected in bone metabolic markers. In addition, the status of bone metabolic turnover in male JU athletes in training may be hypermetabolic and as well as that of female JU athletes with regular menses cycles.

Adult↗
PubMed1997

Low-dose pulse methotrexate inhibits articular destruction of adjuvant arthritis in rats.

The purpose of this study was to determine whether low-dose methotrexate pulse therapy, which had recently become important in the treatment of rheumatoid arthritis, was effective for controlling the progression of articular destruction in rats with adjuvant arthritis. Intraperitoneal methotrexate at a dose of 0.05 or 0.1 mg kg-1 twice weekly inhibited inflammation in rats with adjuvant arthritis, as shown by reduction of the hind-paw volume. Methotrexate also inhibited articular destruction, as shown by X-ray findings. Although the mechanisms by which low-dose pulse methotrexate acts on rat adjuvant arthritis are still unclear, our results imply that it might effectively slow the progression of articular destruction in rheumatoid arthritis in man. In addition, assessment of articular destruction in this animal model might be useful when evaluating new treatments for rheumatoid arthritis.

Animals↗