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D Nishimura

Publications and source records attributed to D Nishimura.

11 recordsLinked to original sources
PubMed1992

Two-dimensional selective adiabatic pulses.

Using the technique of separable k-space excitation, we have designed a two-dimensional selective adiabatic pulse that inverts magnetization from a square region in the xy plane with insensitivity to RF variations. We also have designed a two-dimensional adiabatic pulse that inverts selectively in frequency and in one spatial dimension. The pulses should be useful for both MR imaging and spectroscopy. We present experimental results to demonstrate that the two-dimensional adiabatic pulses are feasible on commercial MR imaging systems.

Humans↗
PubMed1991

A reduced power selective adiabatic spin-echo pulse sequence.

We introduce a selective adiabatic pulse sequence suitable for generating selective spin-echoes for both MR imaging and spectroscopy. The technique is simple; one uses the echo generated by any pair of identical selective adiabatic inversion pulses. The nonlinear phase across the slice is compensated perfectly by the second pi pulse. This compensation is immune to RF inhomogeneity and nonlinearity. For imaging applications, we concentrate on a reduced-power version of the pulse sequence in which time is traded off variably for RF amplitude in the presence of a time-varying gradient. This technique, known as variable-rate excitation, mildly degrades the off-resonant slice profile when applied to amplitude-modulated pulses. We present theoretical explanations and experimental results that show that the variable-rate adiabatic pulses are immune to off-resonant degradation of the magnitude normally encountered in MR imaging.

Brain↗
PubMed1990

Assignment of the gene for the small nuclear ribonucleoprotein E (SNRPE) to human chromosome 1q25-q43.

Small nuclear ribonucleoproteins (snRNPs), which are composed of various U RNAs and several proteins, are components of the mRNA splicing apparatus. The snRNP protein E is encoded by a multigene family which consists of a single expressed gene and several processed pseudogenes. We have used somatic cell hybridization, in situ hybridization, and linkage analysis to both physically and genetically map the expressed E protein gene to human chromosome 1q25-43, with the most probable location being band 1q32. In addition to the snRNP E protein gene, two other snRNP components--the U1 RNA true multigene family and a group of class I U1 pseudogenes--are located on human chromosome 1.

Animals↗
PubMed1990

A detailed multipoint gene map of chromosome 1q.

Utilizing genotyping data for 23 markers, we have constructed a 21-locus multipoint genetic map of the long arm of chromosome 1. Five new RFLPs are reported. The map integrates anonymous loci from previous primary linkage maps and incorporates markers for 10 coding sequences. These markers form a continuous linkage group of 85 cM in males and 141 cM in females. The map was constructed employing the LINKAGE and CRIMAP computational methodologies via a stepwise algorithm.

Algorithms↗
PubMed1990

[Long-term follow-up study of alcoholic liver disease].

Two hundred seventy-one patients with various forms of alcoholic liver disease were followed up for an average of 87.9 months. The survival was the lowest for alcoholic cirrhosis (average 10-year survival: 23.8%). Prognosis was grave especially in cirrhotic patients who continued drinking, owing mainly to the increased death due to gastrointestinal bleeding. The development of hepatocellular carcinoma (HCC) was observed during the first six years only in cirrhosis. The average 5-year probability rate of developing HCC for cirrhosis was 16.3%. The rate was significantly higher for the cirrhotic patients who abstained than for those who continued drinking. Serial biopsies were performed on 66 non-cirrhotic patients who continued drinking. The mean duration of histological follow-up 46.0 months. Cirrhosis developed eventually in 30.3% of the cases. In conclusion, the present study indicates that continued drinking causes progressive liver damage and a poor prognosis. Our data also suggest that abstinence is associated with an increased risk of HCC in cirrhosis. Thus, it is important to recover from alcoholism before cirrhosis develops.

Adult↗
PubMed1989

Low-frequency restoration.

In magnetic resonance imaging, if the object of interest is known to be spatially bounded within the image field-of-view, then the high-intensity, low spatial frequencies can be determined by postprocessing. This allows the system receiver gain to be increased, thereby decreasing the quantitation noise from the analog-to-digital converters. No imaging sequence modifications are required.

Animals↗
PubMed1988

RFLPs and linkage relationships of the human laminin B2 gene.

RFLPs for laminin B2 (LAMB2) are reported. These RFLPs were used to study the linkage relationships of LAMB2 to four other genes on lq: Duffy (FY), renin (REN), decay accelerating factor (DAF), and complement receptor 2 (CR2). Multipoint linkage analysis placed LAMB2 between FY and the cluster including REN, DAF, and CR2. This provides a useful bridging polymorphic marker on lq and establishes significant linkage of LAMB2 to FY (theta = 3.23, z = 3.85) and REN (theta = 0.17, z = 4.88).

Chromosome Mapping↗
PubMed1988

Noise-reduced prostatic MR imaging. Work in progress.

Measurement-dependent filtering, a nonlinear noise-reduction technique, was used to improve the signal-to-noise ratio of in vivo T2-weighted magnetic resonance images of the prostate gland. In both normal and abnormal prostates, the technique considerably reduced noise in T2-weighted images. The technique may provide more accurate depiction of regions of benign prostatic hyperplasia and carcinoma in the prostate.

Filtration↗
PubMed1985

Immunohistochemical detection of alpha-fetoprotein, carcinoembryonic antigen, and ferritin in formalin-paraffin sections from hepatocellular carcinoma.

Paraffin sections of livers from 20 patients with hepatocellular carcinoma were examined by a method using peroxidase antiperoxidase for the detection of alpha-fetoprotein, carcinoembryonic antigen, and ferritin. Ferritin was detected in 70% of the cases, alpha-fetoprotein was in 50% and carcinoembryonic antigen in 30%. The incidence of the detection of these antigens was in accordance with the incidence of these antigens in the sera of patients with hepatocellular carcinoma. Moreover, these antigens were mainly expressed in the well differentiated type of hepatocellular carcinoma by the Edmondson's criteria. Our results also revealed that different antigens were usually present in different tumor cells, although some cells displayed two or more antigens simultaneously. These findings suggest that hepatocellular carcinoma cells are functionally heterogeneous, even if they appear histologically monomorphic.

Aged↗
PubMedDate not supplied

Alcoholic hepatitis with hyperleukocytosis.

We report a fatal case of alcoholic hepatitis with hyperleukocytosis mainly consisting of mature granulocytes in a 43-year-old woman. White blood cell count was increased in parallel with clinical deterioration to 54,800/mm3 with no immature neutrophils on a differential count. The bone marrow aspirate revealed normal maturation and no evidence of hematological malignancy. It has been postulated that severe leukocytosis accompanied by alcoholic hepatitis may be provoked by release of high levels of colony stimulating factor from damaged hepatic cells. However, the present patient showed a normal level of serum granulocyte colony stimulating factor, and could not prove the above assumption.

Adult↗