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Biomedical subjects

H Iida

Publications and source records attributed to H Iida.

At least 343 records · Page 19Linked to original sources
PubMed1992

[A method for measurement of regional cerebral blood flow using N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) SPECT; two scans with one point blood sampling technique].

We have developed a new method to quantitate regional cerebral blood flow (CBF) using 123I-IMP and SPECT. This technique requires two SPECT scans and one blood sampling. Based on the 2 compartment model (influx; k1 and outflux; k2), a table between k2 and ratio of 1st scan counts/2nd scan counts was calculated, and a table look up procedure yielded a unique pair of k1 (CBF) and distribution volume (Vd = k1/k2) for each region of interest (ROI). The arterial input function was obtained by one point blood sampling to calibrate the standard input function, which has been obtained from the previous study on 12 subjects. This method was applied to 5 subjects including 1 healthy volunteer and 4 patients with cerebral infarction, and the regional CBF results were compared with those measured by H2(15)O PET technique. Optimized scan time combination was 40, 180 min which provided the best correlation with H2(15)O-CBF. The Vd values obtained in infarcted regions were significantly smaller than those in normal regions, suggesting the importance of measuring Vd for each ROI.

Aged↗
PubMed1992

Use of the left ventricular time-activity curve as a noninvasive input function in dynamic oxygen-15-water positron emission tomography.

Noninvasive recording of arterial input functions using regions of interest (ROIs) in the left ventricular (LV) chamber obviates the need for arterial cannulation in PET, but it is compromised by the limited recovery coefficient of the LV chamber and by statistical noise. In the present study, a new mathematical model has been developed, which corrects for the spillover of radioactivity both from the myocardium into the LV ROI and the blood into the myocardial ROI. The method requires the measurement of a time-activity curve in the LV chamber during the dynamic H2(15)O PET study and the measurement of the recovery coefficient of the LV ROI using a 15O-carbon monoxide (C15O) scan and venous blood sampling. This approach was successfully validated against direct measurements of the arterial input function using an on-line beta detector in five greyhounds undergoing dynamic H2(15)O PET imaging. This technique also yielded myocardial blood flow (MBF) values which were not significantly different from those obtained with the beta-probe analyses (maximum difference less than 2%), provided that the LV ROIs were sufficiently large to provide good counting statistics. When this model was not applied for large ROIs (small recovery in LV ROI), systematic overestimations in MBF compared with beta-probe analysis (e.g., a factor by 40% for a recovery coefficient of 0.7) were observed. Thus, this technique enabled the prediction of an accurate input function using the LV time-activity curve, and hence, noninvasive quantification of MBF without arterial cannulation.

Animals↗
PubMed1992

[Quantification of regional cerebral blood flow (rCBF) measurement with one point sampling by 123I-IMP SPECT].

A handy method of quantifying regional cerebral blood flow (rCBF) measurement by 123I-IMP SPECT was designed. A standard input function was made and the sampling time to calibrate this standard input function by one point sampling was optimized. An average standard input function was obtained from continuous arterial samplings of 12 healthy adults. The best sampling time was the minimum differential value between the integral calculus value of the standard input function calibrated by one point sampling and the input function by continuous arterial samplings. This time was 8 minutes after an intravenous injection of 123I-IMP and an error was estimated to be +/- 4.1%. The rCBF values by this method were evaluated by comparing them with the rCBF values of the input function with continuous arterial samplings in 2 healthy adults and a patient with cerebral infarction. A significant correlation (r = 0.764 (p less than 0.001)) was obtained between both.

Adult↗
PubMed1992

Cytosolic free calcium concentration in platelets in patients with renovascular hypertension and primary aldosteronism.

To investigate the role of cytosolic free calcium, [Ca2+]i, in secondary hypertension, the levels in platelets from 14 secondary hypertensives (7 renovascular hypertension, 7 primary aldosteronism) were compared with those from 21 essential hypertensives and 15 normotensives by means of the fluorescent indicator, quin-2. The mean BP was significantly higher in both the secondary hypertensives and essential hypertensives (122 +/- 8 and 124 +/- 12 mmHg) than in the normotensives (89 +/- 10 mmHg). Cytosolic free calcium in platelets was significantly higher in the essential hypertensives, but not in the secondary hypertensives, compared with the normotensives (182 +/- 34, 141 +/- 17, 138 +/- 15 nM respectively). There was no significant difference in platelet [Ca2+]i between renovascular hypertension and aldosteronism (142 +/- 19 versus 139 +/- 16 nM). There was no correlation between platelet [Ca2+]i and plasma renin activity, plasma aldosterone concentration or plasma noradrenaline concentration in the three groups. Thus, the increase in platelet [Ca2+]i seen in essential hypertension was not found in patients with secondary hypertension. Our results suggest that the cytosolic calcium handling of secondary hypertensive patients with renal artery stenosis or primary aldosteronism differs from that of essential hypertensives.

Adult↗
PubMed1992

[New quantification of regional cerebral blood flow measurements by 123I-IMP SPECT with the rotating gamma camera--theory and validation of the look-up table method].

A new method of quantifying regional cerebral blood flow (rCBF) measurements by N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) SPECT with a rotating gamma camera was designed. By assuming the 2 compartment model of the kinetic for 123I-IMP, two parameters of rCBF and distribution volume (Vd) of 123I-IMP from brom brain tissue to blood were obtained by the look-up table method and were derived from two simultaneous equations of the early and delayed images. The rCBF values of 3 cases (two normal adults and one brain infarct patient) were calculated by this method and were compared with the values of positron emission tomography (PET) measured at the same time. The average rCBF values in gray and white matter by this method were 40 ml/100 g/min, 27 ml/100 g/min, respectively and correlated significantly to rCBF values by PET (r = 0.598 (p less than 0.001)).

Adult↗
PubMed1992

[Intramedullary neurofibroma in the cervical spinal cord; a case report].

A 62-year-old woman was admitted complaining of clumsiness in both hands. On neurological examination, bilateral hand muscles were weak, both legs were spastic and hyperreflexic, all the extremities were hypoesthetic. Urological examination revealed detruser sphincter dyssynergia. Spinal CT scan demonstrated an iso density mass lesion in the cervical spinal cord, and it was markedly enhanced. On MRI, it was also markedly enhanced by Gd-DTPA. The operative finding was that an oval shaped tumor was buried in the spinal cord and was totally removed. Its histological diagnosis was neurofibroma. Intramedullary neurofibroma is rare and only 18 cases have been reported. In this case the tumor seemed to have arisen at the root entry zone and to have grown sub-pially.

Female↗
PubMed1992

[A case of dural sarcoidosis].

A 26 year-old man, who was treated for meningitis in our hospital previously, was rehospitalized 1 year later because he developed disturbance of consciousness, gait disturbance and urinary incontinence. Blood examination revealed accelerated ESR, elevated GPT, slight elevation of serum Ca, strong positive CRP, and a decrease in PHA and Con A. ACE was within normal range and tuberculin reaction was negative. Lumbar puncture revealed that the initial pressure was 310 mmH2O, cells were 152/3, and protein was 343 mg/dl. Bilateral hilar lymphadenopathy was absent in chest X ray film. Head CT revealed enlarged lateral ventricles and irregularly enhancing nodular lesions in the anterior half of the falx cerebri, and abnormally strong enhancement of the choroid plexus. Ventriculoperitoneal shunt was performed. As a diagnosis was difficult to obtain from the clinical data, biopsy of the nodular lesions was performed. The histopathologic diagnosis was sarcoidosis. Steroid hormone was administered thereafter, and the nodular lesions of the falx disappeared in the follow-up. In the literature, only 8 cases of sarcoidosis of the dura mater have been reported. Since intracranial sarcoidosis is a part of systemic sarcoidosis, its diagnosis is not difficult in most cases. However, in cases difficult to diagnose as in our case, biopsy may be necessary. When nodular lesion occurs in the dura mater, sarcoidosis must be included as a possibility in the differential diagnosis in addition to the usual meningioma, lymphoma, and metastatic brain tumor.

Adult↗
PubMed1991

A DBL-homologous region of the yeast CLS4/CDC24 gene product is important for Ca(2+)-modulated bud assembly.

The CLS4/CDC24 is essential for the budding process of the yeast Saccharomyces cerevisiae. Disruption of the CLS4/CDC24 gene is lethal, and expression of the CLS4 product under the control of the GAL1 promoter is sufficient for cellular growth. The CLS4 product is detected in yeast cell lysate with an apparent molecular mass of 93 kD (854 amino acid residues) and shows homology with the human DBL oncogene product. Temperature-sensitive cdc24-1 mutation is located in the N-terminal portion of the protein whereas Ca(2+)-sensitive cls4-1 mutation is present after the DBL-homologous region (amino acid residues 281-518) near the putative Ca(2+)-binding site. Mutations within the DBL-homologous region are responsible for the Ca(2+)-sensitive phenotype. Thus the CLS4 gene product seems to have several functional domains within the molecule essential for bud assembly.

Amino Acid Sequence↗
PubMed1991

Platelet-derived growth factor (PDGF) and PDGF receptor are induced in mesangial proliferative nephritis in the rat.

We investigated whether platelet-derived growth factor (PDGF), or its receptor (PDGF-R), was upregulated in a rat model of mesangial proliferative glomerulonephritis. A marked increase in both PDGF A- and B-chain mRNA could be demonstrated in glomerular RNA by Northern blot analysis 3 and 5 days after disease induction, corresponding to the time of mesangial cell proliferation. PDGF-R beta-subunit mRNA and protein were also increased in glomeruli in mesangial proliferative nephritis, being maximal at day 5. The principal cells expressing PDGF B-chain appeared by immunostaining to be a subpopulation of mesangial cells; in contrast, the majority of the mesangial cells expressed the PDGF-R beta-subunit protein. Both complement depletion and platelet depletion significantly reduced cell proliferation and expression of both PDGF and PDGF-R. Thus, in mesangial proliferative nephritis there is a platelet- and complement-mediated induction of PDGF A and B chain and PDGF-R beta-subunit gene transcription and protein synthesis. The finding that the majority of PDGF is produced by the mesangial cell supports the role of PDGF as an autocrine growth factor in glomerulonephritis.

Animals↗
PubMed1991

Monitoring of intracellular calcium in Saccharomyces cerevisiae with an apoaequorin cDNA expression system.

A method is described for measuring cytosolic free Ca2+ and its time-dependent changes in the yeast Saccharomyces cerevisiae by using the luminescent protein aequorin as a Ca(2+)-specific indicator. This method with intact yeast cells is labeled "in vivo" to distinguish it from methods with cell extracts, labeled "in vitro." A plasmid in which the apoaequorin cDNA was joined downstream from the glyceraldehyde-3-phosphate dehydrogenase gene promoter was constructed and introduced into yeast cells. The intracellular concentration of apoaequorin expressed by the cDNA was approximately 1 microM, which was high enough to detect the cytosolic Ca2+. Growth of the transformed cells was normal. In the in vitro method, apoaequorin in crude cell extracts was regenerated into aequorin by mixing with coelenterazine, the substrate for the luminescence reaction, whereas in the in vivo method, aequorin was regenerated by incubating intact cells with coelenterazine. Simultaneous addition of 10 mM CaCl2 and 10 microM A23187, a Ca2+ ionophore, to coelenterazine-incorporated cells generated luminescence. Coelenterazine-incorporated cells also responded to native extracellular stimuli. A mating pheromone, alpha-factor, added to cells of mating type a or alpha, generated extracellular Ca(2+)-dependent luminescence specifically in a mating type cells, with maximal intensity occurring 45-50 min after addition of alpha-factor. Glucose added to glucose-starved G0/G1 cells stimulated an increase in extracellular Ca(2+)-dependent luminescence with maximal intensity occurring 2 min after addition. These results show the usefulness of the aequorin system in monitoring [Ca2+]i response to extracellular stimuli in yeast cells.

Aequorin↗
PubMed1991

Calcium-sensitive cls mutants of Saccharomyces cerevisiae showing a Pet- phenotype are ascribable to defects of vacuolar membrane H(+)-ATPase activity.

Ca(2+)-sensitive mutants of the yeast Saccharomyces cerevisiae showing a Pet- phenotype (cls7-cls11) have lesions in a system for maintaining intracellular Ca2+ homeostasis (Ohya, Y., Ohsumi, Y., and Anraku, Y. (1986) J. Gen. Microbiol. 132, 979-988). Genetic and biochemical studies have demonstrated that these Pet- cls mutants are related to defects in vacuolar membrane H(+)-ATPase. CLS7 and CLS8 were found to be identical with the structural genes encoding subunit c (VMA3) and subunit a (VMA1), respectively, of the enzyme. In addition, these five mutants all had vma defects; no vacuolar membrane ATPase activity was detected in the cls cells, and the cls mutants showed a loss of ability to acidify the vacuole in vivo. Measurements of the cytosolic free Ca2+ concentration [( Ca2+]i) in individual cells showed that the average [Ca2+]i in wild-type cells was 150 +/- 80 nM, whereas that in five Pet- cls cells was 900 +/- 100 nM. These data are consistent with the observation that vacuolar membrane vesicles prepared from the Pet- cls cells have lost ATP-dependent Ca2+ uptake activities. The cls defects of vacuolar membrane H(+)-ATPase resulted in pleiotropic effects on several cellular activities, including Ca2+ homeostasis, glycerol metabolism, and phospholipid metabolism. The mutants showed an inositol-dependent phenotype, possibly due to alteration in regulation of phospholipid biosynthesis; the phosphatidylserine decarboxylase activities of the mutants were 15-50% of that of the wild-type cells and were not repressed by the addition of inositol. In contrast to the majority of previously isolated pet mutants (Tzagoloff, A., and Dieckmann, C. L. (1990) Microbiol. Rev. 54, 211-225), the Pet- cls mutants showed no detectable mitochondrial defects. Taking all these findings into account, we suggest that at least six genes, VMA1 (CLS8, subunit a), VMA2 (subunit b), VMA3 (CLS7, subunit c), VMA11 (CLS9), VMA12 (CLS10), and VMA13 (CLS11), are required for expression of the vacuolar membrane H(+)-ATPase activity.

Aerobiosis↗
PubMed1991

Galactose-dependent expression of the recombinant Ca2(+)-binding photoprotein aequorin in yeast.

Aequorin is a Ca2(+)-binding protein that emits light upon reacting with Ca2+ and has been used as a probe for monitoring changes in the intracellular free Ca2+ concentration, [Ca2+]i. The protein consists of three components: apoaequorin (apoprotein), molecular oxygen and a chromophore. The present study was designed to conditionally express the apoaequorin cDNA of the jellyfish Aequorea victoria under the control of the GAL1 promoter in the yeast Saccharomyces cerevisiae and to investigate whether apoaequorin can be accumulated in high enough concentration in the cells to detect a Ca2+ signal in vitro. The results showed that the cells accumulated sufficient amounts of recombinant apoaequorin when incubated in the galactose-based medium and that the protein was active and not toxic to the cells, suggesting that the recombinant apoaequorin may be applicable to monitoring changes in [Ca2+]i in intact yeast cells.

Aequorin↗
PubMed1991

Loss of RCC1, a nuclear DNA-binding protein, uncouples the completion of DNA replication from the activation of cdc2 protein kinase and mitosis.

The temperature-sensitive mutant cell line tsBN2, was derived from the BHK21 cell line and has a point mutation in the RCC1 gene. In tsBN2 cells, the RCC1 protein disappeared after a shift to the non-permissive temperature at any time in the cell cycle. From S phase onwards, once RCC1 function was lost at the non-permissive temperature, p34cdc2 was dephosphorylated and M-phase specific histone H1 kinase was activated. However, in G1 phase, shifting to the non-permissive temperature did not activate p34cdc2 histone H1 kinase. The activation of p34cdc2 histone H1 kinase required protein synthesis in addition to the presence of a complex between p34cdc2 and cyclin B. Upon the loss of RCC1 in S phase of tsBN2 cells and the consequent p34cdc2 histone H1 kinase activation, a normal mitotic cycle is induced, including the formation of a mitotic spindle and subsequent reformation of the interphase-microtubule network. Exit from mitosis was accompanied by the disappearance of cyclin B, and a decrease in p34cdc2 histone H1 kinase activity. The kinetics of p34cdc2 histone H1 kinase activation correlated well with the appearance of premature mitotic cells and was not affected by the presence of a DNA synthesis inhibitor. Thus the normal inhibition of p34cdc2 activation by incompletely replicated DNA is abrogated by the loss of RCC1.

Animals↗
PubMed1991

A new approach of weighted integration technique based on accumulated images using dynamic PET and H2(15)O.

We developed a new technique of weighted integration for the measurement of local cerebral blood flow (LCBF) and the blood-tissue partition coefficient (p) using dynamic positron emission tomography (PET) and H2(15)O. The weighted integration in the new technique is carried out on the equation of the first time integration of the Kety-Schmidt differential equation. Practically, serially accumulated images with sequentially prolonged accumulation times are weighted by two arbitrary functions. The weighting functions do not have to be differentiated because of the exclusion of the differential term in the starting equation. Consequently, the method does not require data at the end of the scan. The technique was applied to H2(15)O dynamic PET performed on four normal subjects, and was verified to provide a better signal-to-noise ratio than the previously developed integrated projection (IP) technique. Computer simulations were carried out to investigate the effects of statistical noise, tissue heterogeneity, and time delay and dispersion in arterial input function. The simulation showed that the new technique provided about a 1.4 times lower statistical error in both LCBF and p at 50 ml 100 g-1 min-1 compared to the IP technique, and it should be noted that the new technique was less sensitive to the shape of the weighting functions. The new technique provides a new strategy with respect to the statistical error for estimation of LCBF and p.

Adult↗
PubMed1991

Increased synthesis of extracellular matrix in mesangial proliferative nephritis.

Extracellular matrix expansion is frequently noted in mesangioproliferative renal diseases. This study investigates the role of immunologic factors in glomerular matrix accumulation. The gene expression of type I and IV collagen, laminin and s-laminin was examined in the rat model of mesangial proliferative glomerulonephritis induced with anti-Thy 1.1 antibody. Northern analysis was performed on glomerular RNA isolated one, three and five days after disease induction and at day 3 following prior complement depletion. Tissue was immunostained for the protein products of these genes as well as for heparan sulfate proteoglycan, entactin and PCNA (a marker of cell proliferation) at days 1, 3, 5, 14, 21 and 42. A seven- to ten-fold increase of collagen IV and laminin mRNA as well as de novo expression of collagen I mRNA occurred at days 3 and 5 corresponding to the time of maximal proliferation. S-laminin mRNA levels only increased three-fold. With the exception of s-laminin, mesangial staining for all examined matrix proteins increased to a maximum at day 5 and decreased thereafter. Focal alterations of the glomerular architecture and matrix persisted at day 42. Complement depletion prevented the histological abnormalities as well as the increased expression of matrix proteins at day 3. These findings indicate that immunologic injury in the mesangium may result in overproduction of extracellular matrix components and may ultimately contribute to the development of glomerulosclerosis.

Animals↗
PubMed1991

Prolonged exposure to industrial noise causes hearing loss but not high blood pressure: a study of 2124 factory laborers in Japan.

To determine the role of noise exposure in the etiology of hypertension, a cross-sectional study was performed by measuring the blood pressure of 2124 male laborers working in a noisy factory. The prevalence of hypertension was 10.2% in group I (85-115 dB), 10.9% in group II (less than 85 dB) and 12.5% in group III (office workers). There was no difference in systolic or diastolic blood pressure among the three groups. There were 358, 439 and 71 laborers in groups I, II and III, respectively, all having worked in the same noise area for more than 10 years. Blood pressure was lower 10 years previously in each group, but the degree of increment did not significantly differ among the three groups. The prevalence of hearing loss was 16.5% in group I, which was significantly higher than that in group II (7.5%) and group III (2.8%). Blood pressure of laborers with hearing loss was equal to that of laborers with intact hearing acuity. There was no significant relationship between hearing loss and the prevalence of hypertension. Thus, prolonged exposure to industrial noise contributes to hearing loss. However, elevation of blood pressure was not found in laborers working in a noisy factory. This finding was not consistant with previously reported findings in the rat. An adaptability to prolonged noise in man may account for this discrepancy.

Adult↗