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Biomedical subjects

Y Mashima

Publications and source records attributed to Y Mashima.

At least 145 records · Page 8Linked to original sources
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↗
PubMed1990

Abnormal hepatobiliary clearance of 99mTc-N-(2,6-diethylphenylcarbamoylmethyl)iminodiacetic acid in the altered state of thyroid--by an analysis of deconvolution method.

Hepatobiliary clearance of 99mTc-EHIDA was investigated in cases with altered thyroid function by deconvolution method. The results indicated that mean hepatic transit time of all control subjects revealed less than 10 minutes. On the other hand, mean hepatic transit time of cases with altered thyroid function revealed prolonged more than 13 minutes. Cases especially showing an elevated serum concentration of TSH compared with normal range (4.6 microU/ml) had a tendency of a high incidence of markedly prolonged mean hepatic transit time. These results suggest that thyroid hormone may influence on the hepatic metabolism of hepatobiliary radiopharmaceuticals. This phenomenon also could partly explain the cause of liver dysfunction seen in subjects with altered states.

Adult↗
PubMed1990

[DNA diagnosis of Leber's hereditary optic neuropathy].

The point mutation at nt11778 in mitochondrial DNA is highly associated with Leber's hereditary optic neuropathy and eliminates a restriction enzyme SfaNI site in American blacks and Caucasians. DNA diagnosis was applied to a male Japanese patient with this disorder and his mother as a carrier. The mitochondrial DNA fragments (255bp) including this mutation were amplified by polymerase chain reaction. SfaNI digested the DNA fragments of normal Japanese subjects, but did not digest those of the patient or the carrier, The mutation within the SfaNI site is also associated with Japanese suffering from this disorder.

Adult↗
PubMed1990

[Diagnostic value of the transesophageal atrial pacing stress for Tl-201 myocardial SPECT].

The stress study for Tl-201 myocardial SPECT (single photon emission computed tomography) of a patient with old myocardial infarction, who had occasionally felt a chest pain for the last 8 months was performed with the transesophageal atrial pacing. The examination was fastly started and regular pacing rates were completely obtained for every pacing rate (50-100/min). In spite of a little amount of the pacing stress, the finding of stress induced ischemia and MI were obtained on this patient. This result suggests that the transesophageal atrial pacing stress might be useful for the evaluation of ischemic heart disease by Tl-201 myocardial SPECT, and is easily applied to the old and the patient with disorder of leg movement.

Cardiac Pacing, Artificial↗
PubMed1990

[Laboratory tests on cancer--cytology].

A comparative study was performed on needle aspiration cytology and the histological grading of 34 cases of small liver cancers. According to the Edmondson-Steiner's classification, 9 of the 34 cases were Grade I, 10 cases were a mixture of Grades I and II and 15 were Grade II or a mixture of Grades II and III or Grades I, II and III. The group consisting of Grade II and mixtures of Grades II and III or Grades I, Ii and III were diagnosed by needle aspiration cytology using cytological criteria described previously, but cases consisting of Grade I and mixtures of Grades I and II were very difficult to diagnose because of the relative lack of cellular atypia, and the diagnostic accuracy in this group was low. Retrospectively, ceLlularity, cellular architecture and the nuclear-cytoplasmic ratio were the most valuable cytological findings in the cases of Edmondson-Steiner's Grade I and the mixture of Grades I and II. In addition, some cases of small liver cancers had characteristically large lipid vacuoles which resembled a signet ring cell. Imprint cytology of neuroblastomas is a rapid diagnostic test which is very useful for differential diagnosis of neuroblastoma from other childhood solid tumors. Recently, flow cytometric DNA analysis and the N-myc oncogene have been proposed as important factors in the estimation of the prognosis of neuroblastomas. Three of fore patients with aneuploid DNA under the age of 1.5 years at diagnosis survive, while five of eight patients with diploid DNA over the age of 1.5 years at diagnosis died during a 12 to 120 month follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

The influence of aniseikonia on the VEP by random-dot stereogram.

Static random-dot stereograms were employed to evaluate the unequal input between two eyes, both objectively by VEP and psychophysically. In subjects with normal binocular function, different levels of artificial aniseikonia (from 2% to 15%) were established by placing several levels of size lenses in front of one eye. Binocular summation in amplitude in the VEP was observed below 5% aniseikonia, and the binocular inhibition took place above 5% aniseikonia. Psychophysically, perception of stereopsis could be maintained between 3% and 5% aniseikonia, but disappeared above 5% aniseikonia. Electrophysiological findings of binocular interaction caused by aniseikonia corresponded to the psychophysical findings, and stereoscopic perception was obtained only in the case of binocular summation in the VEP. In the present study, the amount of tolerable aniseikonia in order to maintain stereopsis was considered to be below 5%.

Adult↗
PubMed1989

[Distribution pattern of density in lumbar vertebra studied with computed tomography: a study of histogram plot].

The bone mineral status of the cancellous bone in the lumbar vertebrae was evaluated by analysing density histograms and measuring the mean density by computed tomography. The results obtained were as follows: (a) the distribution pattern of bone density in lumbar vertebrae revealed a normal distribution. (b) high correlation coefficients between peak density (r = -0.79) or mean density (r = -0.77) and age was obtained in males, whereas peak densities in females were maintained well at ages younger than 50 years and peak densities abruptly decreased after 50 years of age. Osteoporotic vertebrae, in which multiple osteosclerotic changes were observed, had several peak densities and did not show normal density distribution pattern. These results indicated that our methods combining analysis of density histograms and measurement of mean density are useful to evaluate the bone mineral status.

Absorptiometry, Photon↗
PubMed1989

[A new computed tomography method for quantitative analysis of abdominal aortic atherosclerosis].

Clinical evaluation of aortic atherosclerosis has been most commonly performed by visual analysis of aortic calcification on conventional radiographs or X-ray CT. However, precise evaluation of the degree of calcification or mild changes with increasing age can be difficult by these methods of visual analysis. A new quantitative method of evaluating the abdominal aortic atherosclerosis using CT is reported. Target CT scans of the abdominal aorta were performed at the level of the 1st, 3rd and 4th lumbar vertebrae. Two circular regions of interest (ROI) were selected along the outer margin and inner margin of the abdominal aortic wall on CT images, since it was difficult to precisely trace the aortic wall. Histograms of CT value for each pixel were made from two ROIs. A histogram at the ROI of the outer margin was depicted using class values over the maximum CT value in histogram at the ROI of inner margin which indicated flowing blood. A sum of products of the value in each class by the number in that class was divided by the aortic diameter. The value thus obtained was defined as the atherosclerotic index (S.I.). Forty-five cases were studied with this method. Six cases were excluded because of artifacts. The remaining 39 cases (16 males, 23 females) were analyzed. S.I. increased with aging and was higher in men than in women. However, it increased more rapidly in women (8.68/year) than in men (2.73/year). Because this new method employed the CT value, it is more objectively quantitative than previous methods of visual analysis in evaluating abdominal aortic atherosclerosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

[Evaluation of gallbladder emptying in patients with chronic liver disease by 99mTc-EHIDA hepatobiliary scintigraphy].

Gallbladder emptying after intramuscular injection of cerulein was investigated by 99mTc-EHIDA hepatobiliary scintigraphy in 23 patients with biliary disease, 55 patients with chronic liver disease, and 21 normal controls. The mean gallbladder ejection fraction in patients with gallstones and liver cirrhosis was significantly reduced compared with normal controls. (gallstones: 56.3 +/- 21.3%, LC with gallstones: 50.8 +/- 29.6%, LC without gallstones: 55.9 +/- 26.7%, vs. normal controls: 74.4 +/- 12.9%, p less than 0.01). The mechanism for sluggish gallbladder emptying in liver cirrhosis is unknown, however impaired emptying with bile stasis provides a potential pathophysiologic basis for the high frequency of pigment stones.

Adult↗
PubMed1989

[A study of adequate energy, amino acid, and carbohydrate requirements in postoperative total parenteral nutrition--the effect of branched chain amino acid (BCAA) and carbohydrate mixture of glucose, fructose, and xylitol (GFX)].

This study was performed to elucidate adequate energy and amino acid (AA) requirements for TPN patients after abdominal surgery. The effects of AA formula, rich in BCAA (30% BCAA), as a nitrogen source and the carbohydrate mixture of glucose, fructose, and xylitol (GFX = 4:2:1), on nitrogen sparing were also studied. Forty-nine patients having undergone major abdominal surgeries, were divided into 5 groups. The regimens were as follows: G1: 40kcal/kg, standard amino acid (21% BCAA) 1.5g/kg. day, G2: 40kcal/kg, 30% BCAA 1.5g/kg.day, G3: 30kcal/kg, 21% BCAA 1.5g/kg.day, G4: 30kcal/kg, 30% BCAA 1.5g/kg.day, G5: 40kcal/kg, 21% BCAA 1.5g/kg.day. Glucose was the sole carbohydrate energy source in G1 through G4. In G5, GFX was used. (1) Accumulated nitrogen balances during the week immediately after operation were significantly higher in G1 and G2 where higher energy intakes were administered than G3 and G4. (2) The nitrogen balances during the 2nd or 3rd postoperative days in G2 or G4, using 30% BCAA as a nitrogen source, were higher than in G1 or G3 respectively. (3) The changes in serum rapid turnover proteins were not significantly different among these groups. (4) The accumulated nitrogen balance in G5 tended to be higher than that of G1. These results indicate that BCAA rich amino acid formula will induce a more favorable nitrogen sparing effect than a conventional AA formula on TPN patients under surgical stress.

Adult↗
PubMed1988

Simultaneous recording of visual evoked potentials and electroretinograms in patients with unilateral opaque media.

We studied the correlation between preoperative visual evoked potentials (VEPs) and postoperative visual acuities in patients with unilateral opaque media. The fellow eye was used as the control. The filtering effect due to opaque media could be assessed on the basis of the difference of the electroretinogram (ERG) threshold in the two eyes. 'Modified VEPs' were then calculated by eliminating the assessed filtering effects, which improved our ability to detect the potential for visual recovery. In the normal eye, the stimulus threshold for VEP is lower than that for ERG by 2 or 3 log units. Therefore should a higher stimulus threshold be found for VEP than ERG, severe optic nerve damage is highly probable in eyes with media opacties.

Electroretinography↗
PubMed1987

Visual evoked potential in the management of pituitary tumor during pregnancy.

We examined a pregnant woman with chiasmal syndrome in the late stage of pregnancy. Her vision was determined to be seriously threatened after 31 weeks' gestation. Study of the latency of preoperative visual evoked potentials (VEPs) in other patients with pituitary tumor showed that insofar as latency is not delayed, surgical decompression is expected to be followed by functional improvement of the optic pathway. We monitored optic nerve function by serially recorded VEPs, and labor was induced at 38 weeks because there had been no delayed response up to that time. After a decompressive operation, visual field and visual acuity recovered normally. Serially recorded VEPs can provide a useful monitor along with visual field and acuity tests in guiding therapy for a patient with threatened vision in late pregnancy and in determining whether or when to induce labor.

Adenoma↗