Biomedical subjects

N Niki

Publications and source records attributed to N Niki.

6 recordsLinked to original sources

PubMed2001

[Evaluation of computer-assisted diagnosis of small pulmonary nodules using contrast-enhanced dynamic helical CT].

Dynamic helical computed tomography(DH-CT) was performed to examine 45 lesions(23 lung cancers, 2 pulmonary metastasis, and 20 benign nodules) as an application of computer-assisted qualitative analysis of small pulmonary nodules. Based on the three-dimensional(3D) CT image data, the internal structure of the nodule was assessed quantitatively and temporal changes were evaluated. The entire lesion was examined by helical scanning with a beam width of 2 mm(pitch of 1) before contrast enhancement and 2 and 4 minutes after contrast enhancement. Using the digital CT data, the pixels inside the nodules were quantified based on a combination of CT values and 3D curvature in order to differentiate between benign(BN) and malignant nodules (MN). (The numeral score abovementioned was calculated.) The average scores for BN 2 and 4 minutes were -5.72 and -12.8, respectively, and those for MN were 5.51 and 12.0, respectively(p < 0.01). Assuming that a score of 0 or higher indicates a MN based on the CT data 4 minutes. In conclusion, 3D computer-assisted analysis of the internal structure of small pulmonary nodules using contrast-enhanced DH-CT was found to be effective for differentiating between benign and malignant nodules.

Adult↗

PubMed1995

Type I and type II interferons upregulate functional type I interleukin-1 receptor in a human fibroblast cell line TIG-1.

The regulation of type I interleukin-1 receptor (IL-1R) expression by type I, interferon (IFN)-alpha A/D, and type II IFN, IFN-gamma, in a human fibroblast cell line TIG-1 was investigated. After 2 h stimulation with human IFN-alpha A/D or IFN-gamma, the levels of type I IL-1R mRNA increased. We previously reported that IL-1 upregulates transcription and cell surface molecules of type I IL-1R in TIG-1 cells through induction of prostaglandin (PG) E2 and cAMP accumulation. However, indomethacin was unable to inhibit the effect of IFNs, indicating that IFNs augment IL-1R expression through a pathway distinct from that of IL-1. The augmentation was also observed in other fibroblast cell lines. Nuclear run-on assays and studies of the stability of mRNA suggested that the increase in IL-1R mRNA was a result of the enhanced transcription of IL-1R gene. Binding studies using 125I-IL-1 alpha revealed that the number of cell surface IL-1R increased with no change in binding affinity by treatment with these IFNs. Pretreatment of the cells with IFNs enhanced IL-1-induced IL-6 production, indicating that IFNs upregulate functional IL-1R. IL-1 and IFNs are produced by the same cell types, as well as by the adjacent different cell types, and are concomitantly present in lesions of immune and inflammatory reactions. These results therefore suggest that IFNs exhibit synergistic effects with IL-1 through upregulation of IL-1R. Augmented production of IL-6 may also contribute to the reactions.

Cell Line↗

PubMed1994

Deficit of hand preshaping after muscimol injection in monkey parietal cortex.

In order to assess the functional role of the parietal hand movement region, the anterior part of the lateral bank of the intraparietal sulcus (IPS), area AIP, in the visual guidance of hand grasping, we reversibly inactivated several parts of this area with microinjections of Muscimol in a monkey trained to grasp objects of different shapes, sizes and orientations. During the local inactivation, some of the skilled patterns of finger movements were disrupted in the contralateral hand, due to the lack of preshaping to adjust the finger posture to the object; however, no major deficits in visual reaching were observed. The results suggest that area AIP plays a crucial role in the visual guidance of goal-directed hand movements.

Animals↗

PubMed1994

Hypothalamic neuronal histamine regulates feeding circadian rhythm in rats.

To clarify involvement of hypothalamic neuronal histamine in feeding circadian rhythm, we analyzed rat behavioral patterns using chemical probes which affect endogenous histaminergic activity. Sustained infusion of alpha-fluoromethylhistidine (FMH), a specific suicide inhibitor of a histamine-synthesizing enzyme, into the rat third cerebral ventricle disrupted light-dark cycles of feeding, drinking, and ambulatory behavior. Food and water intake and ambulatory activity during the 12-h light period increased, and those during the 12-h dark period decreased after the infusion. The ratio of the light period to the 24-h total period (L/T ratio) increased in all behavioral parameters. Assessed by 3-h cumulative analysis, amplitudes of circadian rhythmicity decreased in all behavioral parameters, whereas only the acrophase of ambulatory activity shifted forward after FMH infusion. Chlorpheniramine, an H1-antagonist, selectively increased food intake during the light and decreased it during the dark period. Consequently, the antagonist increased the L/T ratio in food intake, but did not affect the ratio in water intake or ambulatory activity. Famotidine, an H2-antagonist, did not affect the ratio in any parameter. Thioperamide, an antagonist of auto-inhibitory effects on histamine synthesis and release at presynaptic H3-receptor sites, decreased food intake during the dark, but did not affect the L/T ratio in any parameter. These findings indicate that neuronal histamine may regulate feeding circadian rhythm through the hypothalamic histamine H1-receptor in rats.

Animals↗

PubMedDate not supplied

Three dimensional solid model reconstruction for neurosurgical approach.

Two different types of solid models of neurosurgical pathologies by 3-D reconstruction were presented and examined, and their clinical usefulness was appraised by neurosurgical simulation. Cranial vessel models were proposed by solidifying liquid photopolymer based on 3-D MR angiography data. These models provided total visual and tactile perceptions of the anatomy. Aneurysm model well demonstrated the root of its origin and was useful in preoperative planning. Three dimensional demonstration of arterial angles gave more informations for performing transarterial embolization of aneurysm. This method had advantages in visualising more complicated or minute structures such as cerebral vessels. Intracranial pathologies and the skull base anatomy were demonstrated by milling urethane block based on CT data. These models were useful in deciding the appropriate direction of surgical approach for lesions located in the middle fossa. This method had another advantage to demonstrate the details of anatomical relationships between macroscopic pathologies and surrounding structures. Milled models were useful for the practice of preoperative simulation because urethane was easily processed in comparison with solidified polymer.

Cerebrovascular Circulation↗

PubMedDate not supplied

Computer-aided diagnosis for pulmonary nodules based on helical CT images.

In this paper, we present a computer-assisted automatic diagnostic system for lung cancer that detects nodule candidates at an early stage from helical CT images of the thorax. Our diagnostic system consists of analytical and diagnostic procedures. In the analytical procedure, first we extract the lung and the pulmonary blood vessel regions using the fuzzy clustering algorithm, then we analyze the features of these regions using image-processing techniques. In the diagnostic procedure, we define diagnostic rules utilizing the extracted features which support the determination of the candidate nodule locations. We show the effectiveness of our system by giving the results from its application to image data for mass screening of 450 patients.

Algorithms↗