Search PubMed⌕ Search

Biomedical subjects

N Katayama

Publications and source records attributed to N Katayama.

At least 145 records · Page 8Linked to original sources
PubMed1999

Primary anorectal malignant melanoma: report of a case.

Primary anorectal malignant melanoma is a fairly uncommon but highly malignant disease. This disease is sometimes mistaken for such benign conditions as either a hemorrhoid or rectal polyp. We herein describe a case of early primary malignant melanoma of the anal canal. In this case, magnetic resonance (MR) imaging was found to be useful for diagnosing the melanotic melanoma. We especially emphasize the usefulness of a fat-saturation MR image in distinguishing melanotic melanoma from other rectal tumors.

Aged↗
PubMed1999

Investigation of the time delay between variations in heart rate and blood pressure.

Relationships between fast variations in heart rate and blood pressure are known mainly to reflect parasympathetic activity. To assess parasympathetic function, relationships are investigated using a mutual information analysis, by assuming an information channel between blood pressure (BP) and inter-R-wave interval (RR) derived from the electrocardiogram. The differential sequences of BP and RR are coded into 'alphabets' for analysing fast variations. The averaged mutual information (AMI) is obtained as a function of delay d (beats) of the differential sequence of RR with reference to BP. The AMIs for supine and standing positions are compared. For 23 patients with renal failure, the AMI against d shows posture-independent and delayed-transfer characteristics from fast variations in BP to those in RR. The closest relationship is found with a 2-beat delay with an out of phase relationship. The 28 control subjects exhibit the 2-beat delayed transfer characteristics in the standing position, but are almost synchronous in the supine position. The mutual information analysis of the delay between fast variations in BP and RR explicitly shows a deficit in the parasympathetic regulation in the patients with renal failure.

Adult↗
PubMed1999

Breast parenchymal activity on scintimammography: comparison between bone-seeking agents and 99mTc-sestamibi.

The aim of this study was to evaluate breast parenchymal activity on scintimammography with bone-seeking agents and 99mTc-MIBI. Scintimammography was performed with bone-seeking agents in 61 patients and with 99mTc-MIBI in 33 patients. Activity in the breast parenchyma contralateral to the suspected lesion was visually assessed by two independent observers. Increased breast parenchymal activity was shown in 19 of 61 patients examined with bone-seeking agents, while it was demonstrated in only two of 33 patients examined with 99mTc-MIBI. Breast parenchymal activity of bone-seeking agents was higher in patients aged 50 years or younger than in those older than 50. Increased parenchymal activity of bone-seeking agents may disturb visualization of primary breast cancer especially in relatively young patients. Low parenchymal activity is suggested to be a favorable characteristic of 99mTc-MIBI as a scintimammographic agent.

Adult↗
PubMed1999

Complete agenesis of the dorsal pancreas.

Pancreatic anomalies are occasionally reported, but complete agenesis of the dorsal pancreas is extremely rare. We report a 47-year-old woman with complete agenesis of the dorsal pancreas. This patient initially presented with jaundice. Computed tomography did not reveal the pancreatic corpus or tail. Endoscopic retrograde cholangiopancreatography and magnetic resonance cholangiopancreatography did not visualize the dorsal pancreatic duct. Choledochojejunostomy was performed because she had obstructive jaundice. At laparotomy, there was an enlarged pancreatic head, but no distal pancreas was seen. Histological examination of the pancreatic biopsy specimen showed scattered islets of Langerhans in diffuse fibrosis, with destruction of the glandular parenchyma. This case was diagnosed as complete agenesis of the dorsal pancreas.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1999

Survival of human leukaemic B-cell precursors is supported by stromal cells and cytokines: association with the expression of bcl-2 protein.

We searched for cytokines with the potential to support the survival of human B-cell precursor acute lymphoblastic leukaemia (pre-B ALL) cells. 47 patients with pre-B ALL were classified into four stages: stage I, CD19+CD10-CD20-; stage II, CD19+CD10+CD20-; stage III, CD19+CD10+CD20+cytoplasmic mu-heavy chain (cmu)-; stage IV, CD19+CD10+CD20+cmu. Interleukin (IL)-3 receptor alpha chain (IL-3Ralpha) was expressed in all stages, whereas the expressions of IL-7Ralpha and IL-2Ralpha were pronounced in stages IV and II, respectively. Neither IL-3, IL-7 nor IL-2 supported the survival of pre-B ALL cells. When pre-B ALL cells were layered on stromal, MS-10, cells, viability of the pre-B ALL cells increased. Addition of IL-3 to culture containing MS-10 cells enhanced the survival of pre-B ALL cells in all cases, whereas addition of IL-7 augmented the survival of pre-B ALL cells of some cases of stage III and all cases of stage IV. The survival of pre-B ALL cells was also supported by the conditioned media of MS-10 cells. Stromal-cell-derived factor 1 (SDF-1) supported the survival of pre-B ALL cells. Effects of the conditioned media of MS-10 cells were abrogated by an anti-SDF-1 neutralizing antibody. The extent of survival of pre-B ALL cells supported by stromal cells and IL-3 and IL-7, correlated with the expression level of bcl-2 protein. The effects of stromal cells may be in part related to SDF-1.

Adult↗
PubMed1999

Night-day-night sleep-wakefulness monitoring by ambulatory integrated circuit memories.

A medium-sized portable digital recorder with fully integrated circuit (IC) memories for sleep monitoring has been developed. It has five amplifiers for EEG, EMG, EOG, ECG, and a signal of body acceleration or respiration sound, four event markers, an 8 ch A/D converter, a digital signal processor (DSP), 192 Mbytes IC flash memories, and batteries. The whole system weighs 1200 g including batteries and is put into a small bag worn on the subject's waist or carried in their hand. The sampling rate for each input channel is programmable through the DSP. This apparatus is valuable for continuously monitoring the states of sleep-wakefulness over 24 h, making a night-day-night recording possible in a hospital, home, or car.

Ambulatory Care↗
PubMed1999

Eye movements induced by linear acceleration in humans.

The otolith-function study is remarkably behind the semicanal-function study. In the present paper, we introduced briefly our on-going studies on eye movements including nystagmic elicitation during lateral (Gy) linear acceleration with step and sinusoidal modes using a sled-type accelerator. The eye movements were recorded by EOGs (DC) from subjects who looked at an imaginary target of their straight ahead in darkness during G-loading up to 0.5 G. Corresponding to the +Gy and -Gy segments, nystagmus and/or deviation in eye position were frequently induced in some subjects, but none or slightly in the other. The nystagmus changed the beating direction dependently on the Gy direction, while the eye-deviation could be either direction of compensatory or anticompensatory. In half of subjects, nystagmus elicitation was absent or low at 0.3 G, while it tended to increase above 0.3 G. The nystagmic elicitation was similar to each other between the both modes of acceleration, and directional preponderance (DP) was observed in some subjects. There was no correlation between the DP and the nystagmic slow-phase velocity. Functional meanings of these findings were discussed.

Acceleration↗
PubMed1999

Distinctive actions of interleukin-13 and interleukin-4 on growth of hematopoietic progenitors.

We examined the effects of interleukin (IL)-13 and IL-4 on growth of hematopoietic progenitors from 5-fluorouracil (5-FU)-treated mice, using an in vitro culture system. IL-13 or IL-4 alone failed to support colony formation by enriched marrow cells. IL-4 but not IL-13 in combination with IL-11 yielded a significant number of colonies. Neither IL-4 nor IL-13 affected colony formation supported by IL-3. When tested with two-factor combinations, IL-4 but not IL-13 suppressed the formation of colonies including multilineage colonies in the absence of IL-11. The inhibitory effects of IL-4 were not lineage-specific. Delayed addition experiments demonstrated that IL-4 is inhibitory in the early stage of colony formation. Effects of IL-4 on colony formation by pooled blast cells derived from 5-day culture of post-5-FU marrow cells was not evident. These findings indicate that IL-4 but not IL-13 is a negative regulator of hematopoietic progenitors, suggesting distinctive roles for IL-4 and IL-13 in early hematopoiesis.

Animals↗
PubMed1999

Possible involvement of bcl-2 in regulation of cell-cycle progression of haemopoietic cells by transforming growth factor-beta1.

Transforming growth factor-beta1 (TGF-beta1) acts directly on haemopoietic progenitor cells to regulate their growth. To investigate a possible link between the action of TGF-beta1 and cell death regulators such as bcl-2, we utilized Ba/F3 cells, the interleukin-3 (IL-3)-dependent growth of which could be modulated by TGF-beta1, as well as haemopoietic progenitor cells. We demonstrate here that up-regulation of bcl-2 protein (Bcl-2) as well as that of an inhibitor of cyclin/cyclin-dependent kinase complex, p27, was associated with TGF-beta1-induced deceleration of the cell-cycling of haemopoietic progenitor cells and Ba/F3 cells. The data from cell-cycle analysis of Ba/F3 cells showed that TGF-beta1 retarded the G1 to S phase transition. Analysis of cells with the potential to express Bcl-2 in an inducible manner indicated that up-regulation of Bcl-2 was sufficient for not only an increase in the level of p27 but also to inhibit the cell growth. Using c-kit-overexpressing cells, we observed that the potential of TGF-beta1 to up-regulate the expression of Bcl-2 and p27 could be counteracted by the c-kit ligand, stem cell factor. These results demonstrate that Bcl-2 exerts an essential function in the regulation of G1 to S phase transition of haemopoietic cells by TGF-beta1.

Animals↗
PubMed1999

Sympathetic response to horizontally linear acceleration in humans.

There is considerable evidence that stimulation of the vestibular system has effects on the activities of sympathetic preganglionic neurons in animals and of postganglionic nerves in animals and humans. In previous studies, we showed that the muscle sympathetic nerve activity (MSNA) from the human tibial nerve is enhanced after caloric vestibular stimulation (Cui et al. 1997), whereas the skin sympathetic nerve activity is suppressed during the nystagmus evoked by the caloric vestibular stimulation (Cui et al. 1999). These results suggest that the stimulation of the horizontal semicircular canal has effects on sympathetic outflows to muscle and skin in humans. However, much less is known about the MSNA response to dynamic stimulation of otolith organs in humans. To clarify this issue, we used a linear accelerator to stimulate the vestibular organs, especially otolith organs, and observed the MSNA and hemodynamic responses during movement.

Acceleration↗
PubMed1999

Elicitation of otolithic nystagmus by step and sinusoidal modes of linear acceleration (Gy) in humans.

The vestibular otolith organ, a sensor of linear acceleration, is known to be important not only for posture control and spatial orientation, but also for eye movement control. Niven et al. (1966) have reported that linear acceleration along the Y (left-right, interaural) head axis by using a linear track induces compensatory horizontal eye movements including nystagmus. This was confirmed by several authors using a linear accelerator and a parallel swing. We have already found that a step mode of Gy linear acceleration is useful to elicit otolithic nystagmus and that nystagmus have directional preponderance (DP) (Mori and Katayama, 1998). In the present report, we attempted to compare two modes of acceleration, step and sinusoidal, in nystagmic elicitation induced by linear acceleration.

Acceleration↗
PubMed1999

Influence of postural changes on nystagmic elicitation induced by linear acceleration.

Functional nystagmic eye movements are compensatory responses meant to stabilize the gaze during head movement. Niven et al. (1966) have reported that otolithic nystagmus can be elicited by linear acceleration in humans only along interaural (Y-axis) acceleration (Gy), but not along occipitonasal (X-axis) or head-to-foot (Z-axis) acceleration. This result was reexamined in the present study in normal subjects who elicited lateral (Gy) nystagmus frequently. The nystagmic elicitation was examined by EOG in 4 healthy subjects who were fastened tightly in the chair of a linear accelerator and instructed to look straight ahead at an imaginary target in the dark. The stimulation was five oscillations of a constant 10-m stroke at two different acceleration levels of 0.3 and 0.5 G in a step mode. The X- and Z-axis accelerations did not induce any horizontal or vertical nystagmus, while the Y-axis acceleration did, in agreement with the above report. However, it was found that nystagmic elicitation due to Gy loading tended to be lower in the supine than in the upright sitting position. The present finding that nystagmic slow-phase velocity (SPV) increased with an increase in the G-load also contradicted the above report. Upright subjects who showed G-directional preponderance (DP) in nystagmic elicitation did not always maintain DP when supine. No relation could be seen between DP and SPV, suggesting that DP might be generated by a central mechanism different from SPV control.

Acceleration↗
PubMed1998

Granulocyte colony-stimulating factor and its receptor in acute promyelocytic leukemia.

Expression of granulocyte colony-stimulating factor (G-CSF) receptor (G-CSFR) and in vitro proliferative response to G-CSF were investigated by quantitative immunofluorescence and [3H] thymidine uptake, respectively, in a series of acute myeloid leukemias (AML). The results indicated that G-CSFR was detected at high levels in acute promyelocytic leukemia (APL) cells, in comparison with other types of AML. Moreover, APL cells were also seen to predominantly proliferate in response to G-CSF. Based on these observations, we administered recombinant human G-CSF to a patient with APL in the third relapse that was resistant to both cytotoxic agents and all trans retinoic acid, in an attempt to sensitize the leukemic cells to cell-cycle-dependent agents. Complete remission was achieved. The finding that APL cells are exquisitely responsive to G-CSF supports the view that G-CSF is useful for augmentation of their vulnerability to cell-cycle specific agents.

Adult↗
PubMed1998

Frequent expression of human Thy-1 antigen on pre-B cell acute lymphoblastic leukemia with t(9;22).

Thy-1 (CDw90) is a phosphatidylinositol-anchored protein, and is expressed on human pluripotential hematopoietic stem cells. The expression pattern of this antigen on leukemia cells is still controversial. In this study, 72 adult patients with pre-B cell acute lymphoblastic leukemia (pre-B ALL) were examined for the expression pattern of Thy-1 by using indirect immunofluorescence and reversed transcription polymerase chain reaction (RT-PCR) methods. Twelve cases were judged positive on the basis of conventional immunophenotype criteria. Thirteen cases showed a weak clonal shift on the fluorogram, even though their positive percentages were from 6.7% to 14.9%. Thy-1 gene transcripts were detected in all of the 13 cases showing a weak clonal shift. The study of antibody binding capacity, which was calculated by the mean fluorescence intensity of the test sample on the basis of a calibration curve using standard beads, showed that cases with more than 150 sites/cell could be positive. Thy-1 positivity in pre-B ALL was not associated with the expression of B-cell differentiation antigens. Thy-1 expression was significantly higher in pre-B ALL cases with karyotypic abnormalities than in those with normal karyotype (p = 0.0071). The t(9;22) abnormality was found in 18 of the 25 Thy-1+ cases. Simultaneous expression of transcriptional factors, GATA-2 and SCL, was frequently detected in the Thy-1+ cases. bcr-abl and GATA-2 are thought to play important roles in the proliferation of immature hematopoietic cells. Indeed, cell-cycle analysis showed that the cell population in the S/G2/M phase of the present Thy-1+ cases was less than that in the Thy-1- cases (p = 0.001770). Our data suggest that Thy-1 expression indicates the proliferative status of the leukemia cells, not their phenotypic immaturity.

Adolescent↗
PubMed1998

Increased thrombopoietin levels in idiopathic thrombocytopenic purpura patients with a poor response to steroid therapy.

The serum thrombopoietin (TPO) levels in 61 idiopathic thrombocytopenic purpura (ITP) patients were found to be slightly increased compared with those of 29 normal subjects. The TPO levels of the 15 ITP patients who had a poor response to steroid therapy (i.e. an unchanged platelet count) were higher than those of the 22 ITP patients who had a good response to steroid therapy (i.e. an increased platelet count) and the normal subjects. The TPO levels in the 15 ITP patients whose platelet count was higher than 10 x 10(4)/microl after the discontinuation of steroid therapy significantly higher than those of the normal subjects. The platelet-associated immunoglobulin G (PAIgG) levels in the ITP patients who had a poor response to steroid therapy were slightly increased compared with the normal subjects and the ITP patients who had a good response to the steroid therapy and the nine ITP patients who did not undergo the steroid therapy. The serum TPO level was negatively correlated only with the megakaryocyte count in the ITP patients, and the megakaryocyte count in the ITP patients who had good responses to the steroid therapy was higher than that in those who had poor responses. These data suggest that serum TPO levels might be important for the prediction of the outcome of ITP patients who receive steroid therapy.

Adolescent↗