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Biomedical subjects

D Nishimura

Publications and source records attributed to D Nishimura.

At least 37 records · Page 2Linked to original sources
PubMed1997

Consistent fat suppression with compensated spectral-spatial pulses.

Reliable fat suppression is especially important with fast imaging techniques such as echo-planar (EPI), spiral, and fast spin-echo (FSE) T2-weighted imaging. Spectral-spatial excitation has a number of advantages over spectrally selective presaturation techniques, including better resilience to B0 and B1 inhomogeneity. In this paper, a FSE sequence using a spectral-spatial excitation pulse for superior fat suppression is presented. Previous problems maintaining the CPMG condition are solved using simple methods to accurately program radio-frequency (RF) phase. Next an analysis shows how B0 eddy currents can reduce fat suppression effectiveness for spectral-spatial pulses designed for conventional gradient systems. Three methods to compensate for the degradation are provided. Both the causes of the degradation and the compensation techniques apply equally to gradient-recalled applications using these pulses. These problems do not apply to pulses designed for high-speed gradient systems. The spectral-spatial FSE sequence delivers clinically lower fat signal with better uniformity than spectrally selective pre-saturation techniques.

Adipose Tissue↗
PubMed1997

Identification of a complex congenital heart defect susceptibility locus by using DNA pooling and shared segment analysis.

The identification of genetic loci involved in most forms of congenital heart disease has been hampered by the complex inheritance patterns of these disorders. Atrioventricular canal defects (AVCDs) are most commonly associated with Down syndrome, although non-syndromic cases also occur. Non-syndromic AVCDs have been attributed to multifactorial inheritance. However, the occurrence of a few kindreds with multiple affected individuals has suggested that a major genetic locus can account for the disorder in some families. We have used a combination of DNA pooling and shared segment analysis to perform a high density screen of the entire autosomal human genome in an extended kindred. In so doing, we have identified a genetic locus on chromosome 1 shared by all affected individuals. Our data demonstrate the existence of a congenital heart defect susceptibility gene, inherited as an autosomal dominant with incomplete penetrance, involved in AVCD. Furthermore, our data demonstrate the power of using key isolated kindreds in combination with high density genomic screens to identify loci involved in complex disorders such as congenital heart defects.

Chromosome Mapping↗
PubMed1997

Extrahepatic portosystemic venous shunt without portal hypertension.

A 72-year-old woman was admitted for recurrent episodes of encephalopathy. Laboratory data showed mild liver dysfunction and hyperammonemia, while she had neither anemia nor splenomegaly. The dilated inferior mesenteric vein (IMV) was opacified retrogradely from the superior mesenteric vein by superior mesenteric arteriography, and IMV was found to connect with the inferior vena cava (IVC) through a torturous shunt. No obstruction of the extrahepatic portal vein or hepatic vein was observed by arteriography. Histological evaluation of the liver biopsy indicated remarkable fatty change without cirrhosis. Finally, we diagnosed this case as extrahepatic portosystemic venous shunt without portal hypertension.

Aged↗
PubMed1996

Pseudoaneurysm of the cystic artery associated with upper gastrointestinal bleeding.

Pseudoaneurysm of the cystic artery is a cause of hemobilia, and is extremely rare, with only eight cases having been reported in the world literature. We report a case of pseudoaneurysm of the cystic artery in a 72-year-old Japanese man. The patient experienced epigastric pain and melena, and was found to have jaundice and liver dysfunction. Repeated gastroendoscopy did not reveal the cause of the alimentary tract bleeding; however, color-Doppler ultrasonography detected an aneurysm of the cystic artery in the gallbladder. Selective hepatic arteriography demonstrated that the posterior branch of the cystic artery was markedly dilated and that an aneurysm had formed in the midst of the artery. We diagnosed hemobilia due to the pseudoaneurysm of the cystic artery, and associated gastrointestinal bleeding. Cholecystectomy was performed immediately. Pathologically, the gallbladder showed acute calculous cholecystitis. This case emphasizes the importance of including hemobilia in the differential diagnosis whenever gastrointestinal bleeding is associated with signs of biliary disorder; color-Doppler imaging is a favorable modality for the diagnosis of pseudoaneurysm of the cystic artery.

Aged↗
PubMed1996

Pendred syndrome maps to chromosome 7q21-34 and is caused by an intrinsic defect in thyroid iodine organification.

Exactly 100 years ago, in 1896, Pendred first described the association of congenital deafness with thyroid goitre (MM#274600). The incidence of Pendred syndrome is estimated at 7.5-10/100,000, and may be responsible for as much as 10% of hereditary deafness. The cause of the congenital deafness in Pendred syndrome is obscure, although a Mondini type malformation of the cochlea exists in some patients. The reason for the association between the thyroid and cochlear defects is similarly obscure, leading some investigators to suggest that the two recessive defects may be occurring together by chance in highly consanguineous families. An in vivo defect in thyroid iodine organification in Pendred syndrome patients has been reported. However, the molecular basis of this defect is unknown and the presence of an intrinsic thyroidal defect has not been conclusively demonstrated. We have adopted a genetic linkage study as a first step towards identifying the gene. The availability of an inbred Pendred syndrome kindred allowed us to utilize an efficient DNA pooling strategy to perform a genome-wide linkage search for the disease locus. In this way, we have mapped the disease locus to an approximately 9-cM interval between GATA23F5 and D7S687 on chromosome 7. In addition, we demonstrate an intrinsic thyroid iodine organification defect in a patient's thyroid cells as the cause of the thyroid dysfunction.

Chromosome Mapping↗
PubMed1996

A gene for autosomal dominant late-onset progressive non-syndromic hearing loss, DFNA10, maps to chromosome 6.

Late-onset non-syndromic hearing impairment is the most common type of neurological dysfunction in the elderly. It can be either acquired or inherited, although the relative impact of heredity on this type of loss is not known. To date, nine different genes have been localized, but none has been cloned. Using an extended American family in which a gene for autosomal dominant late-onset non-syndromic hearing impairment is segregating, we have identified a new locus, DFNA10, on chromosome 6.

Chromosome Mapping↗
PubMed1996

Autosomal dominant Charcot-Marie-Tooth axonal neuropathy mapped on chromosome 7p (CMT2D).

Clinical, electrophysiological and genetic linkage studies were performed on a large autosomal dominant family with Charcot-Marie-Tooth axonal neuropathy type 2 (CMT2) with 38 members of which 14 were affected. Onset of the disease was between 16 and 30 years of age with weakness and atrophy of the hands more severe than of the feet with slow progressive course in 12 patients. Deep tendon reflexes were absent in the upper extremities and decreased in the lower extremities. There was distal hypesthesia for touch, proprioception and vibration sense for the hands more than for the feet. Motor nerve conduction velocities showed normal values (48-53 M/s) with normal latencies (2-3 msec) and electromyography revealed signs of denervation. Genetic linkage analysis used 167 short tandem repeat markers (STRPs) spaced throughout the 22 autosomes. Linkage to the short arm of chromosome 7 at 7p14 was found using the marker D7S435 (Z = 4.83 at theta = 0). Flanking markers were D7S1808 and D7S1806 and the genetic distance between them was 6.8 cM. The multipoint linkage analysis gave a peek multipoint lod score of 6.89 between the markers D7S1808 and D7S435. Linkage analysis showed significantly negative lod scores (with values less than -2) with markers of chromosomes 1 and 3 where CMT axonal forms have been previously mapped. PFGE analysis indicated the absence of the CMT1A duplication. Our findings are consistent with a new genetic type of axonal CMT neuropathy designated by us as CMT2D. Potential candidate genes are multiple T-cell gamma receptor genes which map to the same cytogenetic interval as CMT2D neuropathy.

Charcot-Marie-Tooth Disease↗
PubMed1996

Case report: multiple cancers: hepatocellular carcinoma and adenocarcinomas of the common bile duct and the gall-bladder in a woman with primary biliary cirrhosis.

We present a case of primary biliary cirrhosis associated with simultaneous triple cancers: a hepatocellular carcinoma and adenocarcinomas of the common bile duct and gall-bladder. A 70 year old Japanese woman, who had been diagnosed with primary biliary cirrhosis (stage 2 by Scheuer) 15 years before, was admitted to Koseiren Kamo Hospital in a comatose state. Laboratory data were as follows: the ammonia level was high (164.0 micrograms/dL), the antimitochondrial antibody showed a 320-fold increase, a high level of alpha-fetoprotein was indicated (2677 ng/mL), hepatitis B surface antigen was negative and hepatitis C antibody by enzyme immunoassay was negative, although a test for the RNA of hepatitis C virus by polymerase chain reaction was positive (10(3.5) copies/50 microL). The patient's condition gradually worsened and the patient died of liver failure. Autopsy showed triple cancers in the liver (hepatocellular carcinoma; trabecular type, moderately differentiated), the common bile duct (well-differentiated papillary adenocarcinoma) and the gall-bladder (well-differentiated papillary adenocarcinoma) with primary biliary cirrhosis (stage 4). Primary biliary cirrhosis has been believed to be a low risk for the development of hepatocellular carcinoma, despite the high risk of extrahepatic malignancy. The simultaneous occurrence of triple cancers with primary biliary cirrhosis, to the best of our knowledge, has never been reported. The present case may provide additional evidence for a predisposition to malignancy in primary biliary cirrhosis.

Adenocarcinoma↗
PubMed1996

Case report: fibrolamellar hepatocellular carcinoma in a Japanese woman: a case report and review of Japanese cases.

Fibrolamellar hepatocellular carcinoma (FLHCC) is an entity distinct from ordinary hepatocellular carcinoma and is very rare in Oriental countries. We present here a Japanese case of FLHCC in a 25 year old woman, and review Japanese cases of FLHCC. The patient had mild abdominal pain when the hepatic tumour was revealed by ultrasonography. Hepatitis B surface antigen (HBsAg) and anti-hepatitis C antibody were negative and serum alpha-fetoprotein (AFP) was within the normal limit. Ultrasound-guided fine needle biopsy was performed and the tumour was histologically diagnosed as FLHCC. A right lobectomy of the liver was then performed. Macroscopically, the tumour (10 x 10 x 8 cm) was circumscribed, rather hard and yellowish white. Microscopically, neoplastic hepatocytes were polygonal and large with eosinophilic cytoplasm, which contained pale bodies. A number of fibrous stroma were arranged in thin parallel bands. Consequently, the case was diagnosed as FLHCC. In Japan, approximately 18,000 people die of ordinary hepatocellular carcinoma annually, while only nine cases (including the present case; six males, three females) of FLHCC in Japanese subjects have been reported previously. The mean age of the Japanese cases of FLHCC is 20.9 years old. One case with positive HBsAg, liver cirrhosis and high level of AFP was observed of nine cases. The nature of FLHCC in Japanese subjects may not be significantly different from that in Caucasians, except for male predominance.

Adult↗
PubMed1996

Case report: multiple systemic lymph node metastases from a small hepatocellular carcinoma.

Extrahepatic lymph node metastases from hepatocellular carcinoma (HCC) are usually observed in patients with advanced and poorly differentiated HCC. We encountered a patient with multiple, systemic lymph node metastases from a small HCC (18 mm in diameter), which was nodular and had a capsule at the time of resection (a partial hepatectomy of the postero-inferior subsegment of the right lobe of the liver). Widespread lymphadenopathy resembling malignant lymphoma developed 2 months after surgery. A biopsy specimen from a supraclavicular lymph node revealed metastatic HCC. The patient died 2.5 months after the detection of the lymphadenopathy. Lymph node metastases can occur in small HCC less than 2 cm in diameter and may adversely affect the long-term prognosis of patients with these curatively resectable small HCC.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

Use of a DNA pooling strategy to identify a human obesity syndrome locus on chromosome 15.

Bardet-Biedl syndrome is a heterogeneous autosomal recessive disorder characterized by obesity, mental retardation, polydactyly, retinitis pigmentosa and hypogonadism. Patients with this disorder also have a high incidence of hypertension, diabetes mellitus, and renal and cardiovascular anomalies. Three independent loci causing Bardet-Biedl syndrome have previously been reported. In this study, we we utilized a DNA pooling approach using DNA samples from a highly inbred Bedouin kindred to identify a new Bardet-Biedl syndrome locus on chromosome 15. The results further demonstrate the genetic heterogeneity of this disorder. In addition, the results demonstrate the efficiency of the DNA pooling approach for identifying recessive disease loci in highly inbred human populations.

Chromosomes, Human, Pair 15↗
PubMed1995

Primary malignant lymphoma of the liver associated with cirrhosis induced by hepatitis C viral infection.

We present a case of primary malignant lymphoma of the liver of B cell origin with cirrhosis induced by hepatitis C viral infection. A 75-year-old Japanese woman with chronic liver dysfunction was admitted for hepatic tumors. The tumors were hypoechoic on ultrasonography and hypodense on computed tomography. Antibody to hepatitis C virus was positive. Ultrasonically guided biopsy was performed, and we diagnosed hepatic lymphoma with cirrhosis induced by hepatitis C virus clinically and immunohistochemically. This case may be the first report of the association of these two diseases, and may provide additional evidence of a predisposition to malignancy in cirrhosis.

Aged↗
PubMed1994

Identification of a Bardet-Biedl syndrome locus on chromosome 3 and evaluation of an efficient approach to homozygosity mapping.

Bardet-Biedl syndrome is an autosomal recessive disorder characterized by mental retardation, obesity, retinitis pigmentosa, polydactyly and hypogonadism. Individuals with this disorder also have an increased incidence of hypertension, diabetes mellitus, and renal and cardiac anomalies. We previously identified a locus on chromosome 16 causing this disorder, and provided evidence that Bardet-Biedl syndrome is heterogeneous. In this study, we identify another Bardet-Biedl syndrome locus on chromosome 3 and confirm the non-allelic heterogeneity of this disorder in Bedouin populations. In addition, we demonstrate the feasibility of using pooled DNA samples from members of large kindreds as an efficient approach to homozygosity mapping.

Chromosome Mapping↗
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↗