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Y Mashima

Publications and source records attributed to Y Mashima.

At least 19 recordsLinked to original sources
PubMed1992

A deletion in the ornithine aminotransferase gene in gyrate atrophy.

Gyrate atrophy (GA) is an autosomal recessive chorioretinal degenerative disease of the eye caused by an inborn defect of the nuclear encoded mitochondrial enzyme ornithine aminotransferase (OAT). We have described previously a GA patient with a 5.0-kilobase pair truncated EcoRI OAT gene fragment and the absence of OAT mRNA on Northern blot analysis. Cloning and sequencing analysis of the truncated gene fragment revealed a 1,072-base pair (bp) deletion including the entire exon 6, starting in intron 5, 172 bp upstream of exon 6 and ending in intron 6, 772 bp downstream of exon 6. A short direct repeat sequence (AGGAGC), resembling the sequence shown to cause DNA polymerase alpha to pause, and sequences capable of forming hairpin loops were both present at the 5' and 3' break-points of the deletion. Reverse transcription-polymerase chain reaction amplification of the patient's RNA with OAT primers yielded DNA fragments of two different sizes, consistent with a low level expression of OAT mRNA. Direct sequencing of the smaller fragment demonstrated the complete absence of exon 6 sequence in the mRNA predicted from the deletion, causing a reading frame shift which results in a premature termination codon at position 192. The mutation in the other allele has been demonstrated by polymerase chain reaction, denaturing gradient gel electrophoresis, and direct sequencing also to be a premature termination codon in exon 6. The absence of detectable OAT mRNA in this patient is consistent with these premature termination mutations because they have been shown to decrease the level of mRNA, especially if present early in the coding sequence.

Amino Acid Sequence↗
PubMed1992

A single-base change at a splice acceptor site in the ornithine aminotransferase gene causes abnormal RNA splicing in gyrate atrophy.

Gyrate atrophy (GA) is an autosomal recessive eye disease involving a progressive loss of vision due to chorioretinal degeneration in which the mitochondrial matrix enzyme ornithine aminotransferase (OAT) is defective. Two sisters with GA are described in this study in whom an A-to-G substitution at the 3' splice acceptor site of intron 4 in one allele of the OAT gene results in a truncated OAT mRNA devoid of exon 5 sequence. The mutation in the other allele was identified to be a mis-sense mutation at codon 318 by denaturing gradient gel electrophoresis and direct sequencing of the polymerase chain reaction (PCR)-amplified DNA. Thus, these GA patients are compound heterozygotes with respect to mutations in the OAT gene that result in inactivation of OAT.

Adenine↗
PubMed1992

[MR study of the brain stem in elderly subjects].

Findings in patients in whom brain stem lesions were suspected were studied by a high-field-strength (1.5 T) MR imager. MR scans were obtained in 97 patients over a 10-month period. The mean age was 71 years (range, 39-94 years). A high incidence of infarction and lesions showing a high signal on T2-weighted image, but an almost normal signal on the T1-weighted image were observed at the pons in elderly cases. Furthermore, cases in which these two findings were observed, had a high incidence of lesion at other regions than pons. Cases with a past history of hypertension had higher incidence of lesions at the pons than normotensive patients (alpha less than 0.01). These findings suggest that MRI examination in the elderly could detect a high incidence abnormal lesions at the brain stem as well as in basal ganglia.

Aged↗
PubMed1992

[Studies on stable control of blood sugar by continuous administration of insulin through isolated intestinal loop].

Insulin (INS) has been known to be absorbed through the intestine in small amounts and to decrease blood sugar (BS) levels. However, stable control of BS has not been attained by intestinal intake of INS. To elucidate the possibility of a surgical approach to control hyperglycemic states, Thiry-Vella loops or upper jejunal loop fistulae were constructed in mongrel dogs in hyperglycemic states. Hyperglycemic states (around 400mg/dl) were induced by injecting streptozotocin. Lente insulin was administered every day to control hyperglycemia, except for the days for studies. As we confirmed that co-administration of aprotinin (TR) or nafamostat mesilate (FT) was necessary, to decrease BS by infusing INS into the intestinal loops, safe and effective dose levels were determined by series of preliminary infusion studies in the intestinal loops of diabetic dogs. By continuous infusion of these doses into the jejunal loop fistulae, a long term stable blood sugar control was attained in the diabetic dogs as long as 7 days. These results suggest that continuous infusion of INS with antiproteolytic adjuvants like TR or FT into the isolated small intestinal loop can control BS in hyperglycemic states.

Animals↗
PubMed1992

[A case of coronary spasm during the operation for lung cancer].

We reported a case of coronary spasm during the operation for lung cancer. A 72-year-old man underwent left upper lobectomy for lung cancer under general anesthesia with the aid of thoracic epidural anesthesia. Preoperative examinations did not reveal any clinical problems in the past. Hypotension and premature ventricular beats were observed for several times during operation due to the compression of the heart and left pulmonary artery by the surgeon's hands in stopping brisk bleeding. After this event, ST-segment of ECG was elevated abruptly. Intravenous administration of nitroglycerin was effective to relieve the coronary spasm in this case. Possible triggering factors were mechanical injury of the coronary artery due to compression of the heart, vagal stimuli under thoracic epidural anesthesia and alpha-stimulating drugs to treat hypotension. The importance of preoperative evaluation of coronary lesions, perioperative treatments with nitrates and calcium-channel blockers, and avoidance of intraoperative triggering factors are emphasized to prevent the coronary spasm.

Aged↗
PubMed1992

[Adequate requirements of energy and protein in postoperative total parenteral nutrition].

Adequate requirements of energy and protein in post operative total parenteral nutrition (TPN) were determined by studying the effects of energy and protein dose on nitrogen retention at varying levels of surgical stress assessed by urinary excretion of total catecholamines. Fifty-two patients received esophagectomy (severe stress), and gastric or colorectal operations (moderate stress) fed exclusively by TPN perioperatively were divided into 6 groups according to the dose level of protein and energy; Group I: 40 kcal, 1.0 g.protein/kg.day (9 patients), Group II: 40 kcal, 1.5 g.protein/kg.day (11 patients), Group III: 40 kcal 2.0 g.protein/kg.day (8 patients), Group IV: 40 kcal, 3.0 g.protein/kg.day (7 patients), Group V: 30 kcal, 2.0 g.protein/kg.day (11 patients), and Group VI: 50 kcal, 2.0 g.protein/kg.day (6 patients). Daily nitrogen balance (NB) and urinary excretion of total catecholamines (U-CA) were determined everyday pre- and post-operatively. Significantly negative correlations between U-CA and NB were observed. Statistically significant differences among the correlations of all groups were recognized. In moderate stress, increasing dose of protein and energy improved NB, and positive NB was achieved when 1.5-2.0 g.protein/kg.day with 35-40 kcal/kg.day was provided. Protein dose exceeding 3.0 g/kg.day caused the rise of BUN. In severe stress, such as following esophagectomy, NB was not improved by increasing dose of nutrients.

Aged↗
PubMed1992

Nonsense-codon mutations of the ornithine aminotransferase gene with decreased levels of mutant mRNA in gyrate atrophy.

A generalized deficiency of the mitochondrial matrix enzyme ornithine aminotransferase (OAT) is the inborn error in gyrate atrophy (GA), an autosomal recessive degenerative disease of the retina and choroid of the eye. Mutations in the OAT gene show a high degree of molecular heterogeneity in GA, reflecting the genetic heterogeneity in this disease. Using the combined techniques of PCR, denaturing gradient gel electrophoresis, and direct sequencing, we have identified three nonsense-codon mutations and one nonsense codon-generating mutation of the OAT gene in GA pedigrees. Three of them are single-base substitutions, and one is a 2-bp deletion resulting in a reading frameshift. A nonsense codon created at position 79 (TGA) by a frameshift and nonsense mutations at codons 209 (TAT----TAA) and 299 (TAC----TAG) result in abnormally low levels of OAT mRNA in the patient's skin fibroblasts. A nonsense mutation at codon 426 (CGA----TGA) in the last exon, however, has little effect on the mRNA level. Thus, the mRNA level can be reduced by nonsense-codon mutations, but the position of the mutation may be important, with earlier premature-translation termination having a greater effect than a later mutation.

Adult↗
PubMed1991

[The effect of human growth hormone on protein metabolism in the surgically stressed state].

The effects of human growth hormone (HGH) on protein metabolism were investigated. In the experimental study, thirty one male SD rats receiving TPN were divided into 2 groups (control group & HGH group). Cumulative nitrogen balance after burn in HGH group was significantly higher than in control group. (p less than 0.05) Rates of whole body protein turnover (Q), together with those of synthesis (S) and breakdown (B) were significantly higher in HGH group than in control group. (p less than 0.01) Nitrogen balance significantly correlated with urinary total catecholamine excretion in both groups. (p less than 0.01) The difference of correlations of nitrogen balance to urinary total catecholamine excretion between two groups was statistically significant (p less than 0.01) when compared by analysis of covariance. In the clinical study, 12 patients after sub-total esophagectomy receiving TPN were divided into 2 groups (control group & HGH group). Cumulative nitrogen balance after operation in HGH group was significantly higher than in control group. (p less than 0.01) Q,S, and B were higher in HGH group than in control group. Increase of S was statistically significant. (p less than 0.01). These results indicate that HGH may be greatly beneficial in improving protein metabolism in the surgically stressed state.

Adult↗
PubMed1991

[Catabolism of lipoprotein-X (Lp-X) induced by infusion of 10% intralipid].

In order to clarify the metabolism of Lipoprotein X (Lp-X) induced by intravenous Intralipid 10%, in vitro experiments using purified Lp-X from the sera of the patients receiving Intralipid 10% were carried out. 1) Lp-X or high density lipoprotein (HDL) was incubated with J-774 macrophages laden with [3H] cholesterol. Marked extraction of cholesterol from macrophages by Lp-X as well as HDL was observed. 2) [3H] cholesterol labelled Lp-X or oxidized LDL (o-LDL) was incubated with J-774 macrophages. Incorporation of Lp-X into macrophages was negligible comparing to o-LDL. 3) [3H] cholesterol labelled Lp-X, low density lipoprotein (LDL), or HDL was incubated with Hep G2 cells was less than LDL, but similar to that of HDL. These results indicated that Lp-X extracted cholesterol from peripheral tissues during its formation, and it was not catabolized by the scavenger pathway, but catabolized by the LDL pathway of hepatocytes.

Cells, Cultured↗
PubMed1991

Mitochondrial DNA analysis of Leber's hereditary optic neuropathy.

A mitochondrial DNA (mtDNA) mutation associated with Leber's hereditary optic neuropathy (LHON) was recently observed. The presence or absence of the mutation was analyzed in 10 Japanese patients whose clinical course and fundus findings were consistent with LHON. Four of them had at least one maternally related individual who also had bilateral optic atrophy, and were diagnosed as "definite LHON". The other 6 cases lacked any record of optic nerve disease in maternally related individuals, and were diagnosed as "possible LHON". We found the mutation at the SfaNI site of mtDNA in 3 out of the former 4 cases, and in 5 out of the latter 6 cases. This result demonstrates the clinical and diagnostic importance of mtDNA analysis, especially with possible cases of LHON, and suggests that an alternative mutation associated with LHON is also present in Japanese patients.

Adolescent↗
PubMed1990

[Cine MRI of the ascending aorta in the elderly with respect to the flow signal void and aortic valve morphology].

Cine flow MRI was performed on a 1.5 Tesla system to observe signal intensity of blood flow within the ascending aorta in the elderly who had no aortic stenosis and to determine frequency of the flow signal void. Coronal and sagittal imaging planes of the ascending aorta were obtained in 27 aged patients with no known cardiac diseases (14 men and 13 women, mean age of 76) and 7 young volunteers (7 men, mean age of 24), utilizing ECG-gating. GRASS (gradient-recalled acquisition in steady state), and a flow compensation sequence. The young volunteers presented little or no signal void within the ascending aorta. In 26 (96%) of the 27 aged patients, on the other hand, signal void was demonstrated in the blood flow distal to the aortic valve during systole. The maximum length of the signal void that was measured at 318-632 msec after the R wave of ECG ranged from 33 to 97 mm. Conventional and Doppler echocardiography was used to evaluate motion and morphology of the aortic valve in 19 of the 27 aged patients. Eighteen of these 19 subjects had aortic signal void on cine MRI. Echocardiography showed sclerotic changes of the aortic valve (i.e., increased echogenicity of the cusps and/or commissure fusion) in 10 (53%) of the 19 subjects. The mean maximum length of the signal void in the 10 patients with aortic valve sclerosis was significantly greater than that in the 9 patients with echocardiographically normal valve (68 vs. 45 mm, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[Variable threshold levels for estimation of renal uptake of 99mTc-dimercaptosuccinic acid based on single photon emission computed tomography].

To calculate renal uptake of 99mTc-dimercaptosuccinic acid (DMSA) more accurately using single photon emission computed tomography (SPECT), it is necessary to estimate values of threshold level, which corresponds to the ratio of kidney to background (BG ratio). Thus the phantom and clinical studies were conducted. Six kinds of renal phantoms of 80 to 339 ml, contained different radioactivity of 37 to 485 MBq were prepared. These phantoms were placed in a larger body phantom filled with 1 to 50% of radioactivity representing background. Clinical application of this method was also performed. Results were as follows. 1) A significant correlation between phantom volumes and estimated volumes obtained using threshold level based on BG ratio calculated on tomographic images was found (r = 0.99). 2) A significant correlation between total counts in estimated volumes and radioactivities in phantoms was recognized (r = 0.94). 3) Known radioactivity in phantoms and radioactivity in estimated volumes were highly related (r = 0.98). 4) Clinical application showed valuable results in patients with renal dysfunction. Thus, this method can calculate more accurate renal uptake of 99mTc-DMSA.

Adult↗