Biomedical subjects

Y Hiraki

Publications and source records attributed to Y Hiraki.

At least 37 records · Page 2Linked to original sources

PubMed2001

Altered hepatic hemodynamics caused by temporary occlusion of the right hepatic vein: evaluation with Doppler US in 14 patients.

PURPOSE: To evaluate with Doppler ultrasonography (US) the altered hepatic hemodynamics caused by temporary occlusion of the right hepatic vein. MATERIALS AND METHODS: The study group consisted of 14 patients being considered for hepatic arterial infusion or transarterial embolization. In all patients, maximum peak velocity of the blood flow in the right portal vein was measured with Doppler US before and during the occlusion of the right hepatic vein. In 13 patients, color Doppler US was performed to evaluate Doppler signal in the portal venous branch in the occluded area before and during occlusion. Average peak velocity in the right hepatic artery in eight patients was measured by using a transducer-tipped guide wire before and during occlusion. RESULTS: Maximum peak velocity of the right portal vein significantly decreased with occlusion (P <.01). Hepatic venous occlusion changed the Doppler signal in the portal venous branch in the occluded area from hepatopetal to no signal in 10 patients; to weakened hepatopetal in two; and to hepatofugal in one. Average peak velocity of the right hepatic artery showed a decrease or plateau for 15-30 seconds after the start of occlusion and then a rapid increase to reach a plateau at around 75-90 seconds, with 1.5-2 times as much velocity as that before occlusion. CONCLUSION: Increase in hepatic arterial velocity is accompanied by a decrease in the portal velocity with temporary occlusion of the right hepatic vein; the expected increased drainage through the portal vein was almost undetectable.

Aged↗

PubMed2001

Kinematic magnetic resonance imaging (MRI) of the normal shoulder: assessment of the shapes and signals of the superior and inferior labra with abductive movement using an open-type imager.

A preliminary study was conducted to evaluate the superior and inferior glenoid labra with abductive movement using an open-type MR unit in asymptomatic healthy volunteers. Both fast low angle shot (FLASH) and turbo spin echo (TSE) images were obtained to evaluate the shapes of both the superior and inferior labra, as well as to assess changes in signal at these sites. As the abduction angle was increased, the shape of the superior labrum changed from round or triangular to crescentic and a higher signal was frequently seen. At an abduction angle of 150 degrees, an increase in signal was seen in one-half of the superior labra; this increase was noted more frequently in volunteers over 40 years of age. In some of the superior labra, the increase in signal seen at 150 degrees abduction disappeared on subsequent images obtained at 0 degrees abduction. Hence, the increase in signal was considered to be a reversible change. The shape of the inferior labrum tended to change from crescentic to triangular or round. An increase in signal in the inferior labrum was unrelated to the abduction angle. Abductive kinematic studies using an open-type MR unit provides information about the morphology of the superior and inferior labra, as well as information about signal changes occurring at these sites.

Adult↗

PubMed2001

Recanalization 24 months after endovascular repair of a large internal iliac artery aneurysm with use of stent-graft.

An 83-year-old man with a large internal iliac artery aneurysm (IIAA) was treated with the use of stent-graft, suggesting successful results at 3, 6, and 12 months after treatment. However, 24-month follow-up computed tomography showed minor peripheral opacification of the IIAA. The patient underwent surgical endoaneurysmorrhaphy. No previous report of long-term recanalization of a satisfactorily thrombosed iliac artery aneurysm at 2 years or more after stent-grafting has been previously reported. Further follow-up studies need to be performed on the present procedure before anyone can confidently recommend it in regard to its long-term safety.

Aged↗

PubMed2001

Experimental study of fast and ultrafast T2-weighted imaging sequences using AMI-25 superparamagnetic iron oxide (SPIO).

The objective of this study was to evaluate fast and ultrafast T2-weighted images (T2WI), including echo planar imaging (EPI), using an AMI-25 agar phantom. Image quality for conventional spin echo (CSE) and turbo spin echo (TSE) was almost equivalent. In high-resolution TSE, image quality was highest due to the use of a 512 x 256 matrix. Half-Fourier single-shot turbo SE (HASTE) was associated with blurring of images, and turbo-gradient SE (TGSE) showed a deterioration of image quality. EPI also suffered from poor image quality because this method is very sensitive to magnetic field inhomogeneity. CSE showed good signal-to-noise ratio (S/N) and contrast ratio (CR), but also required the longest imaging times. Among the TSE sequences, TSE with a short echo train length (ETL) was superior in terms of S/N. The CR of EPI and fast low angle shot (FLASH) images were improved in proportion to the effective echo time (TE). At present, TSE is inferior to CSE in terms of S/N and CR. However, taking into consideration scanning time, TSE with a short ETL is thought to be suitable for routine examinations. Effective TE is an important factor in gradient echo (GRE) examinations.

Contrast Media↗

PubMed2001

The effect of calcium on Fas-mediated apoptosis and secondary necrosis of Jurkat cells.

Our previous study using a new microscopic system indicated that apoptotic cells undergo secondary necrosis during treatment with anti-Fas antibody and calcium. In this study, we compared the time-lapse appearance of apoptosis and secondary necrosis of Jurkat cells during treatment with anti-Fas antibody with and without calcium in individual cells. Apoptosis developed in 97% and 81% of cells during 36-hour-treatment with anti-Fas antibody with and without calcium, respectively. The apoptosis of Jurkat cells showed a characteristic pattern of time-lapse morphological change. Less than 1% of the apoptotic cells divided into apoptotic bodies. There was budding in all the other apoptotic cells, but no apoptotic bodies formed. We confirmed that secondary necrosis occurs in individual apoptotic cells during treatment with anti-Fas antibody. Neither the pattern of time-lapse morphological change nor the time interval between the beginning of apoptotic budding and secondary necrosis were related to the presence of calcium. This study clarified the characteristic pattern of time-lapse morphological change in Jurkat cells during treatment with anti-Fas antibody, and presented direct evidence that individual apoptotic cells undergo secondary necrosis. The presence of calcium did not affect the pattern of morphological change or the time interval between the beginning of apoptotic budding and secondary necrosis.

Apoptosis↗

PubMed2001

Expression and localization of angiogenic inhibitory factor, chondromodulin-I, in adult rat eye.

PURPOSE: To determine the role in the eye of chondromodulin (ChM)-I, which has been identified in cartilage as an angiogenic inhibitor, the expression and localization and a possible function of ChM-I were investigated. METHODS: Expression and localization of ChM-I in rat eyes were examined by RNase protection assay and in situ hybridization and by immunostaining, using an antibody against a synthetic peptide. The effect of recombinant ChM-I on tube morphogenesis of retinal endothelial cells was examined in culture. RESULTS: The rat ChM-I gene was determined to encode the open reading frame of 334 amino acid residues, and ChM-I mRNA was exclusively expressed in cartilage, eye, and cerebellum in rats. ChM-I mRNA expression was evident in the iris-ciliary body, retina, and scleral compartments, but not in other compartments of the eye. In situ hybridization revealed mRNA expression in the ganglion cells, inner nuclear layer cells, and pigment epithelium in the retina and in the nonpigment epithelium of the ciliary body. Immunoreactive ChM-I was present in these cells and also in the vitreous body. Western blot analysis detected an approximately 25-kDa band of ChM-I presumed as a secretory form in the aqueous humor and vitreous body and an approximately 37-kDa band as a precursor form in the retina. Recombinant human ChM-I inhibited tube morphogenesis of human retinal endothelial cells in vitro. CONCLUSIONS: These observations indicate a potential role for ChM-I in inhibition of angiogenesis in the rat eye.

Amino Acid Sequence↗

PubMed2001

[Prognostic factors of eating function in tube-fed infants and young children].

To investigate prognostic factors for eating function of dysphagic infants and young children and to propose a guideline for more reasonable future treatment, we retrospectively evaluated clinical findings at the initial examination of 51 tube-fed infants and young children who visited our center, and correlated them to the grade of improvement of their eating function after treatment. The patients were divided into good and poor groups according to the abilities of swallowing, and a multiple survival time analysis was performed in the former. The rate of successful tube-extraction during treatment was adopted as indices of improvement. We found that in the poor group the following factors are significantly associated with higher rate of tube-extraction: shorter period of dysphagia prior to the treatment, younger age to start treatment for eating, onset of feeding impairment after 8 months old, and the grade of the severity scores up to 2. In the good group, the children who received treatment by 36 months old had a high rate of tube-extraction. Based on these findings, we proposed a guideline for future treatment.

Child, Preschool↗

PubMed2001

[Studies on kinetic viscoelasticity of slow muscle fibers--2. Dynamic stiffness changes studied by quick release method and frequency response method].

PURPOSE: To evaluate the mechanical properties of slow fibers and fast fibers which make up the extraocular muscles in rabbits. SUBJECTS AND METHOD: I studied the contractile properties and viscoelastic properties of the superior rectus muscle(SR) and the retractor bulbi muscle (RB) of rabbits using the quick release method and the frequency response method. RESULTS: In the quick release method, isometric tension transients were slower in the SR than in the RB. In the frequency response method, the muscle length is perturbed sinusoidally to measure kinetic viscoelasticity. In resting muscle, dynamic stiffness was not changed with increasing frequency. In contracted muscle, dynamic stiffness was increased with increasing frequency, and the rate of increase was greater in the SR than in the RB. CONCLUSION: It was concluded that the viscoelasticity of the activated cross bridge is greater in slow fibers than in fast fibers.

Animals↗

PubMed2001

[A case of posterior mediastinal ganglioneuroma with fat tissue].

We present a rare case of posterior mediastinal ganglioneuroma with fat tissue. A 50-year-old man visited our Department of Internal Medicine because of hypertension and fatty liver. On screening with abdominal CT a soft tissue tumor was found in the posterior mediastinum. CT and MRI revealed that the tumor appeared to have an abundant fatty component. To obtain a definitive diagnosis, the tumor was resected thoracoscopically. The histological diagnosis was ganglioneuroma. A ganglioneuroma containing a fat component has rarely been reported after cross-sectional imaging. We infer that the tumor may have resulted from spontaneous regression, with subsequent infiltration of adipose tissue from the posterior mediastinum.

Adipose Tissue↗

PubMed2001

Age-related clinical and neurophysiologic characteristics of intractable epilepsy associated with cortical malformation.

PURPOSE: To elucidate the relationship between the characteristics of cortical malformation (CM) and those of associated epilepsy, and also to investigate the prognostic value of the clinical and magnetic resonance imaging (MRI) findings for the seizure and mental outcome. METHODS: We studied 41 patients with CM and epilepsy, and the patients were divided according to the age at onset of epilepsy into two groups: one group of 15 patients with very early onset before age 3 months, and the other group of 26 patients with onset at 3 months or later. Statistical relationship was examined between the types of dysplastic lesions demonstrated by MRI and the age at onset of epilepsy. The effects of the onset age and the features of CM on the outcome of seizures and mental or developmental state also were analyzed. RESULTS: The very early-onset epilepsy was related to the dysplastic patterns of reduced sulci and blurred cortical-subcortical junction, which suggested focal CM, whereas the later-onset epilepsy was related to polymicrogyria. The age at onset of epilepsy was related to the poor seizure outcome, and both the onset age and wide distribution of CM were related to severe retardation. CONCLUSIONS: The type of CM influences the expression of associated epilepsy, especially its age-related features. The age at onset of epilepsy plays an important role in the seizure and mental outcome.

Adolescent↗

PubMed2000

A novel alternatively spliced fibroblast growth factor receptor 3 isoform lacking the acid box domain is expressed during chondrogenic differentiation of ATDC5 cells.

To determine the role of fibroblast growth factor (FGF).FGF receptor (FGFR) signaling in chondrogenesis, we analyzed the gene expression of alternatively spliced FGFRs during chondrogenic differentiation of ATDC5 cells in vitro. Two isoforms of FGFR3 were expressed in these cells. One was the complete form of FGFR3 (FGFR3) already reported, and the other was a novel one that lacks the acid box domain (FGFR3DeltaAB). The gene of FGFR3DeltaAB was expressed in undifferentiated ATDC5 cells. In contrast, the transcripts of FGFR3 were not detectable in undifferentiated cells but increased during cellular condensation, which is an obligatory step for chondrogenic differentiation. FGFR1 and FGFR2 expression was higher than that of FGFR3 in undifferentiated cells. The gene expression of cell cycle inhibitor p21 was induced during cell condensation and correlated best with the expression of FGFR3 among the FGFR isoforms expressed. The differential expression of FGFR3 isoforms during chondrogenesis suggests that these isoforms may play different roles in the regulation of growth and differentiation in chondrocytes. To define the mitogenic response of FGFR3DeltaAB and FGFR3 to FGFs, their cDNAs were stably transfected into mouse BaF3 pro-B cells. FGFR3 preferentially mediates the mitogenic response to FGF1 and poor response to FGF2. In contrast, FGFR3DeltaAB mediated a higher mitogenic response to FGF2 as well as to FGF1. In addition, FGFR3DeltaAB responds to FGF1 at lower concentrations of heparin than FGFR3 does. These results suggest that the acid box plays an important role in the regulation of FGFR3 to mediate biological activities in response to FGFs.

Alternative Splicing↗

PubMed2000

Does diffusion-weighted magnetic resonance imaging enable detection of early ischemic change following transient cerebral ischemia?

To examine the usefulness of diffusion-weighted imaging for detecting neuronal damage following ischemia, dynamic changes in diffusion-, T1- and T2-weighted images of rats subjected to 10 min of 4-vessel occlusion and of humans who had suffered 10-20 min of cardiac arrest were observed. In rats, no remarkable alteration was observed on day 1. On day 3, however, diffusion-weighted images showed high signal intensity in the hippocampal area, in which the apparent diffusion coefficient was significantly lower than that of the control (760+/-28x10(-6) mm(2)/s in control vs. 480+/-29x10(-6) mm(2)/s on day 3, P<0.0001). Histological observation revealed microvacuolation in 92+/-4% of pyramidal neurons in the CA1 region. On day 7, the hyperintensity in diffusion-weighted images had disappeared and microvacuolation had also disappeared in the CA1 region, but severely disrupted pyramidal neurons containing pyknotic nuclei had appeared in the CA1 region instead. In humans, diffusion-weighted images did not show any apparent abnormality in the cerebral cortex on the day of resuscitation. On day 3, however, diffusion-weighted images consistently showed hyperintensities in the temporal or occipital cortex, and these hyperintensities had disappeared in images obtained on days 7 and 14. From day 14, T1-weighted images showed laminar hyperintensity, suggesting laminar necrosis, along the cortex, where diffusion-weighted images showed high signal intensity on day 3. These results suggested that diffusion-weighted imaging has a potential for detection of the occurrence of microvacuolation and is useful for detecting the progression of ischemic changes in humans following global ischemia.

Aged↗

PubMed2000

Requirement of autocrine signaling by bone morphogenetic protein-4 for chondrogenic differentiation of ATDC5 cells.

Mouse EC cell line ATDC5 undergoes differentiation to form cartilage nodules via the cellular condensation stage in the presence of insulin. ATDC5 cells expressed transcripts for bone morphogenetic protein-4 (BMP-4), and type IA and type II BMP receptors. Moreover, cells retained responsiveness to BMP-4, which induced the formation of chondrocytes in the culture. When transfected with a kinase domain-truncated type IA BMP receptor construct, cells failed to undergo differentiation beyond the condensation stage even in the presence of insulin. The soluble form of type IA BMP receptor also blocked the formation of chondrocytes in a dose dependent manner. These lines of evidence suggested that autocrine BMP-4 signaling is required for the conversion of chondrogenic precursor cells into chondrocytes.

Animals↗

PubMed2000

Nontumorous decrease in Tc-99m GSA accumulation.

Nontutimorous decrease in 99mTc-GSA accumulation has not been well covered in the literature. Understanding of this phenomenon is, however, essential for accurate evaluation of regional hepatic function. Scintigrams (transaxial SPECT) of 269 patients who underwent 99mTc-GSA liver scintigraphy were reviewed for the presence of nontumorous decreases in 99mTc-GSA accumulation. Nontumorous decreases in 99mTc-GSA accumulation were seen in 32 of 269 patients (12%). In 16 of the 32 patients (6%), nontumorous decreases in 99mTc-GSA accumulation corresponded to regional decrease in portal venous flow. The causes of such decrease in portal venous flow were portal thrombus of hepatocellular carcinomas in eight patients, portal venous stenosis or occlusion by hilar cholangiocarcinomas in five patients, inter alia. In eight patients (3%), the regions with decreased 99mTc-GSA accumulation correlated with massive hepatic necrosis in fulminant hepatitis, scar in hepatitis, or confleuent in portal venous flow, lobar biliary stasis, or both. In four patients (1.5%), the exact causes of nontumorous decrease in 99mTc-GSA accumulation could not be determined.

Adult↗

PubMed2000

Chondromodulin-I as a novel cartilage-specific growth-modulating factor.

Cartilage is unique among mesenchymal tissues in that it is resistant to vascular invasion due to an intrinsic angiogenesis inhibitor. Chondromodulin-I (ChM-I), a 25-kilodalton glycoprotein purified from bovine epiphyseal cartilage on the basis of growth-promoting activity for chondrocytes, was recently identified as an angiogenesis inhibitor. Human ChM-I cDNA revealed that the mature protein consists of 120 amino acids and is coded as the C-terminal part of a larger transmembrane precursor. Expression of ChM-I cDNA in CHO cells indicated that mature ChM-I molecules were secreted from the cells after post-translational modifications and cleavage from the precursor protein at the predicted processing site. ChM-I stimulated growth and colony formation of cultured chondrocytes, but inhibited angiogenesis in vitro and in vivo. In situ hybridization and immunohistochemistry revealed that ChM-I is specifically expressed in the avascular zone of cartilage in developing bone, but not present in the late hypertrophic and calcified zones that allow vascular invasion. ChM-I actually inhibited vascular invasion into cartilage that was ectopically induced by demineralized bone matrix in nude mice, leading to the suppression of replacement of cartilage by bone in vivo. These results suggest that ChM-I participates in the angiogenic switching of cartilage, and that the withdrawal of its expression allows capillary in-growth, which triggers the replacement of cartilage by bone during endochondral bone development.

Amino Acid Sequence↗

PubMed2000

A novel in vitro culture system for analysis of functional role of phosphate transport in endochondral ossification.

In vivo expression of the type III sodium-dependent phosphate transporter (NaPiT) Glvr-1 during endochondral ossification, suggests a functional role for inorganic phosphate (Pi) transport in cartilage calcification. For further analysis of this relationship, an in vitro model of endochondral ossification is required. In this context, we investigated the characteristics of Pi transport in the new chondrogenic cell line ATDC5 in relation to extracellular matrix (ECM) formation and mineralization. Pi uptake in ATDC-5 cells and in isolated matrix vesicles (MVs) is mediated by an Na-dependent Pi transporter with a pH dependency characteristic of a type III Pi carrier (lower activity at alkaline pH). Northern blot analysis indicated that ATDC-5 cells express Glvr-1 transcripts during the various stages of their maturation with a maximal level during the proliferating stage. In isolated MVs, Pi transport activity was maximal at day 21, concomitant with the beginning of type X collagen messenger RNA expression. These events preceded the initiation of matrix mineralization, which was apparent at day 25, and then gradually increased until day 47. This temporal relationship between maximal Pi transport activity in MVs and the expression of a marker of mineralizing chondrocytes is compatible with the possible involvement of Pi transport in the ECM calcification observed in ATDC-5 cell cultures. In conclusion, these observations suggest that ATCD-5 cells in culture represent a promising model for the analysis of a functional role of Pi transport in the initial events of endochondral ossification.

Biological Transport↗

PubMed2000

Immunohistochemistry of chondromodulin-I in the human intervertebral discs with special reference to the degenerative changes.

The expression of the matrix protein chondromodulin-I has been studied in human intervertebral discs of 101 people using immunohistochemical analyses. The purpose of this report is to present data on the metabolic changes that were found to occur in the chondrocytes of intervertebral discs during development and aging. Chondromodulin-I was highly expressed during the gestational period and gradually decreased after maturation. It was detected in both the extracellular matrix and chondrocytes in the zone of hypertrophic cartilage, the zone of proliferative cartilage and the zone of resting cartilage in fetal discs. It was also present in the annulus fibrosus, nucleus pulposus and end-plate cartilage in mature discs. In degenerative discs, chondromodulin-1 immunoreactivity tended to be elevated in the remaining chondrocytes. Our findings suggest that the expression of the protein is developmentally regulated and upregulated through a defense mechanism against the degenerative processes of the aged intervertebral disc.

Adolescent↗

PubMed2000

A phase II study of cisplatin and 5-fluorouracil with concurrent hyperfractionated thoracic radiation for locally advanced non-small-cell lung cancer: a preliminary report from the Okayama Lung Cancer Study Group.

A recent meta-analysis and randomized studies have demonstrated that combined chemoradiotherapy is associated with a survival advantage for selected patients with locally advanced unresectable non-small-cell lung cancer (NSCLC). We conducted a phase II study of combined chemoradiotherapy to find a more effective combination of drugs and radiation than those previously reported for such patients. Between January 1994 and November 1996, 50 previously untreated patients with locally advanced unresectable NSCLC (stage IIIA with N2 or IIIB disease) were entered in this study. Patients were required to have Eastern Cooperative Oncology Group performance status < or = 2, age < or = 75 years and adequate organ function. Treatment consisted of three cycles of cisplatin (20 mg m(-2), days 1-5) and 5-fluorouracil (5-FU) (500 mg m(-2), days 1-5) every 4 weeks, and concurrent hyperfractionated thoracic radiation (1.25 Gy twice daily, with a 6-h interfraction interval; total radiation dose, 62.5-70 Gy). Of the 50 patients entered, 37 (74%) responded to this chemoradiotherapy, including two (4%) with complete response. By a median follow-up time of 41.0 months, 35 patients had died and 15 were still alive. The median time to progression for responding patients was 14.1 months (range, 2.6-51.3+ months). The median survival time was 18.7 months, with a survival rate of 66.0% at 1 year, 46.0% at 2 years and 27.6% at 3 years. Survival outcome was strongly affected by the extent of nodal involvement (median survival time, 27.4 months for N0-2 disease (n = 37) vs 10.7 months for N3 disease (n = 13); P = 0.007). The major toxicities of treatment were leukopenia and neutropenia (> or = Grade 3, 58% and 60% respectively). Other toxicities of > or = Grade 3 included thrombocytopenia (26%), anaemia (26%), nausea/vomiting (16%) and radiation oesophagitis (6%). Treatment-related death occurred for one patient. Our findings suggest that cisplatin and 5-FU in combination with concurrent hyperfractionated thoracic radiation is effective and feasible for the treatment of locally advanced unresectable NSCLC. The short-term survival in this study appeared to be more encouraging than those of similar chemoradiation trials. A randomized trial will be needed to compare the combination of cisplatin and 5-FU with other platinum-based regimens together with concurrent hyperfractionated thoracic radiation. In addition, in future studies, inclusion criteria for N3 disease with or without supraclavicular involvement should be reconsidered to correctly evaluate the effect of combined chemoradiotherapy for locally advanced unresectable NSCLC.

Adult↗