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Biomedical subjects

M Yamada

Publications and source records attributed to M Yamada.

At least 811 records · Page 45Linked to original sources
PubMed1997

Age-independent constancy of mineral contents in human vertebra and auditory ossicle.

To elucidate age-related changes of mineral contents in human bones, element contents of human vertebrae and auditory ossicles were determined by inductively coupled plasma atomic-emission spectrometry. The cervical, thoracic, and lumbar vertebrae were removed from 12 vertebral columns. The mallei of auditory ossicle were removed from 27 cadavers. It was found that average relative contents (RCs) of calcium and phosphorus in cervical, thoracic, and lumbar vertebrae remained almost constant within ages ranging from 46 to 99 y. In addition, it was found that the RCs of calcium and phosphorus in men's and women's mallei remained constant within ages ranging from 40 to 98 yr. These results support the view that there is no significant age-dependent change of mineral contents in human bones.

Aged↗
PubMed1997

High accumulations of calcium and phosphorus in women's pubic symphysis.

To elucidate compositional changes of the pubic symphysis (PS) by aging, elements of pubic symphysis (PSs) removed from 26 cadavers were determined by inductively coupled plasma atomic-emission spectrometry. It was found that the relative contents (RCs) of calcium and phosphorus in women's PSs were about three- and five-fold amounts as compared with those in men's PSs, respectively. In contrast, the RCs of sulfur, magnesium, sodium, and iron in women's PSs were somewhat lower than those in men's PSs. The accumulations of calcium (Ca) and phosphorus (P) in women's PSs occurred mainly beyond the age of 70-yr-old, but did not occur in men's PSs.

Adult↗
PubMed1997

High accumulation of elements in the human femoral artery.

The relative contents (RCs) of elements in the femoral arteries as well as the thoracic aorta, coronary, basilar, and radial arteries from 26 subjects within the age range between 55 and 92 yr old, were analyzed by inductively coupled plasma atomic emission spectrometry. The RCs of calcium and phosphorus in the femoral arteries started to increase before the age of 60 yr. The RCs of magnesium increased after the age of 70 yr. However, the RCs of sulfur did not change significantly within the age range between 55 and 92 yr. With regard to localization of the mineral accumulations in the femoral arterial wall, it was found that the accumulations of calcium and phosphorus occurred only in the tunica media, only in the tunica intima, or in both the tunica media and the tunica intima. The manner of accumulation of calcium and phosphorus in the femoral arterial wall was different from that in the aortic wall. The average RCs of calcium in the 26 specimens were the highest in the femoral artery, followed in descending order by the thoracic aorta, coronary, basilar, and radial arteries. The average RCs of phosphorus were highest in the thoracic aorta, followed by the coronary, femoral, basilar, and radial arteries. It is noted that the accumulation of mineral elements never occurred uniformly in all the arteries.

Aged↗
PubMed1997

Unsharp masking technique using multiresolution analysis for computed radiography image enhancement.

An unsharp masking technique (USM) is one of the image processing methods used in the computed radiography (CR) system. To further promote the performance of the USM, we developed the NEW-USM processing that can control the frequency enhancement characteristics flexibly and accommodate an extensive range of diagnostic targets. The NEW-USM and USM were performed on femur images acquired by computed radiography (model FCR9000; Fuji Medical Systems USA Inc, Stamford, CT), and the resulting images were compared. In the NEW-USM image, bone structures are enhanced as sharply as in the USM image, whereas the surrounding soft tissue structures, such as muscle are enhanced more strongly than in the USM image. Furthermore, the absence of the bone structure that may suggest pathological change is more obvious in the NEW-USM image. The newly developed NEW-USM can appropriately enhance diagnostic information over the whole range of image frequencies, thereby expanding utility of the USM.

Algorithms↗
PubMed1997

Discrimination of spinal fracture with various bone mineral measurements.

For several different bone mineral measurements and various skeletal sites, we compared capability to discriminate between women in various age decades with and without spinal fracture, and attempted to identify the most effective cutoff level in discrimination of spinal fracture. The subjects were 88 women aged 50-59 years (including 32 with fracture), 95 women aged 60-69 years (including 54 with fracture), and 34 women aged 70-79 years (including 18 with fracture). Spinal trabecular and cortical bone mineral density (BMD) were measured using quantitative computed tomography (CT), and spinal, radial (ultra-distal, 10% distal and 33% distal), and calcaneal BMD were measured by dual X-ray absorptiometry. These BMD values were obtained in each subject on the same day. Three statistical techniques-Student's t-test, the logistic regression analysis, and the receiver operating characteristics (ROC) analysis- were applied and accuracy was calculated using the various cutoff values. The capability to discriminate between women with and those without fracture using these BMD values was different among the three age groups. In women aged 50-59 and 60-69 years, all measurements showed good capabilities for discriminating women with fracture. In women aged 70-79 years, these measurements showed lower capability than in those aged 50-59 and 60-69 years, but among them, the calcaneal and ultradistal radial BMD showed relatively good capability. The 10% and 33% distal radial BMD values were not useful in the detection of the high risk women with fracture. The cutoff BMD values for discrimination of women with fracture varied according to the sites and methods of measurement. For each specific age group, the most suitable measurement methods and the appropriate skeletal sites should be considered, and the effective cutoff values to discriminate those with fracture may differ according to the measurement methods, the skeletal sites examined, and age.

Absorptiometry, Photon↗
PubMed1997

Relationship of spinal fracture to bone density, textural, and anthropometric parameters.

To investigate risk factors for spinal fracture, we studied the relationship between the prevalence of asymptomatic spinal fracture and various morphological measures including spinal bone mineral density (BMD) in women. A total of 122 women ranging in age from 55 to 79 years were studied. The group consisted of 46 women aged 55-59 years (18 with fracture), 51 women aged 60-69 years (26 with fracture), and 26 women aged 70-79 years (14 with fracture). BMD of cortical and trabecular bone from L1 to L3 was measured using quantitative computed tomography (QCT). Run-length analysis was applied to evaluate the spinal trabecular textural features using CT images; the texture indices which represent the mean width of trabecular (the T-texture) and that of intertrabecular spaces (the I-texture) were obtained. Anthropometric factors including body weight and height, psoas muscle area, and vertebral bone volume were measured using CT images. Among the various factors, trabecular BMD in women aged 55-69 years showed the highest odds ratio for the presence of fracture per standard deviation (SD) decrease in bone density. However, in women aged 70-79 years, the highest odds ratio was observed for trabecular texture index but not for trabecular BMD. The I-texture in women aged 55-59 years, the muscle area in women aged 60-69 years, and cortical BMD and muscle area in women aged 70-79 years were also considered significantly related to the risk of fracture.

Age Distribution↗
PubMed1997

Antimetastatic effect of recombinant human macrophage-colony-stimulating factor against lung and liver metastatic B16 melanoma.

We studied the effect of recombinant human macrophage-colony-stimulating factor (rhM-CSF) on the formation of lung and liver metastases following the i.v. injection of the B16 melanoma subline (B16 LiLu) into mice. When rhM-CSF was administered before the B16 inoculation, the number of tumor metastases decreased in the lung and liver. However, the administration of rhM-CSF after B16 inoculation did not produce an antimetastatic effect in the lung, but did in the liver, B16 cells labeled with 5-[125I]-iodo-2'-deoxyuridine (125I-dUrd) were injected and the arrest of tumor cell emboli was examined in the capillary beds of the lung and liver of mice treated with either vehicle or rhM-CSF. In both groups, there were the same numbers of B16 cells in both the lung and the liver 3 minutes after the B16 injection, and almost all tumor cells died within 24 h. However, the number of cells surviving in the lung was decreased in mice injected with rhM-CSF (37%). There was no difference in the number of cells in the livers of mice treated either with vehicle or rhM-CSF in the first 24 h after tumor cell injection. The administration of rhM-CSF increased NK 1.1+ cells in the mouse spleen and facilitated NK activity in vivo. At the same time, the administration of an anti-NK 1.1 antibody blocked the antimetastatic effect of rhM-CSF in the lung but not in the liver. The antibody was effective only when it was injected before the B16 inoculation. These results suggest that the antimetastatic effect of rhM-CSF in the lung was mediated by NK 1.1+ cells within 24 h of B16 injection. In contrast, the antimetastatic effect of rhM-CSF in the liver was mediated not only by NK 1.1+ cells but also by other antimetastatic systems such as macrophages.

Animals↗
PubMed1997

Overexpression of thioredoxin does not confer resistance to cisplatin in transfected human ovarian and colon cancer cell lines.

PURPOSE: We have previously reported increased expression of thioredoxin (TRX) in cell lines with both acquired and intrinsic cisplatin (cDDP) resistance. We found that the expression levels of TRX correlate with cellular resistance to the drug. The purpose of this study was to elucidate whether TRX induces cDDP resistance in the absence of other intracellular changes. METHODS: We developed cell lines stably expressing high levels of TRX by transfection of human ovarian cancer A2780 and colon cancer HT-29, and examined their sensitivity to cDDP. RESULTS: The TRX transfectants expressed two- to threefold more TRX with corresponding activities than the parental cells or mock transfectants. TRX-transfected HT-29 cells expressed higher levels of TRX than cDDP-resistant variant cells. Both TRX-transfected A2780 and HT-29 cells showed no resistance to cDDP. Though TRX-transfected A2780 cells showed 1.8-fold increased resistance to H2O2, resistance to adriamycin and mitomycin C, which generate oxygen radicals, was not observed in the transfectants. CONCLUSIONS: These results suggest that TRX may be necessary but insufficient to induce resistance against cDDP as well as other chemotherapeutic drugs.

Antineoplastic Agents↗
PubMed1997

Resolution of protein-losing hypertrophic gastropathy by eradication of Helicobacter pylori.

UNLABELLED: There is as yet no consensus about the need for treatment of Helicobacter pylori infections, except for H. pylori-associated peptic ulcer. We present a 3-year-old boy with a 3-month history of oedema and hypoproteinaemia associated with hypertrophic gastropathy. Abdominal scintigram using intravenous 99mTc-labelled human serum albumin scintigraphy and direct measurement of protein in gastric juice proved that serum proteins were massively secreted in the stomach. Histological findings of mucosal inflammation were observed and H. pylori was isolated from the gastric mucosa. The protein loss promptly stopped within 2 weeks of the beginning of eradication therapy. CONCLUSION: Protein-losing hypertrophic gastropathy may be induced by Helicobacter pylori-associated gastritis and should therefore be carefully evaluated by histological and bacteriological examination to provide a basis for eradication of H. pylori.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1997

Preventing symblepharon formation with a gelatin sponge in the eye of a patient with an alkali burn.

PURPOSE: To report a patient with symblepharon caused by an alkali injury whom we treated by using a gelatin sponge. METHODS: Four days after the burn, a gelatin sponge was inserted into the upper conjunctival sac to separate the raw conjunctival surfaces. RESULTS: The gelatin sponge adhered to the tarsal side of the upper fornix and was kept there for 11 days until no epithelial defect was visible in the bulbar conjunctiva. No symblepharon formation was observed 6 months after the injury. CONCLUSION: Application of a gelatin sponge proved to be a simple and effective way of preventing symblepharon formation after an alkali burn.

Alkalies↗
PubMed1997

Overlap of Guillain-Barre syndrome and Bickerstaff's brainstem encephalitis.

The nosological relationship between Bickerstaff s brainstem encephalitis (BBE) and Guillain-Barre syndrome (GBS) has yet to be clarified. We report results of the autopsy of a patient for whom overlapping BBE and GBS was diagnosed clinically. This and similar cases support the original authors' hypothesis that BBE is closely related to GBS.

Aged↗
PubMed1997

Pathogenesis of the neurotoxicity caused by anti-GD2 antibody therapy.

After treatment of melanomas with anti-GD2 monoclonal antibody (MAb) (14G2a), some patients develop sensorimotor demyelinating polyneuropathy with and without the syndrome of inappropriate antidiuretic hormone (SIADH). To clarify what causes the neurotoxicity of anti-GD2 MAb, we investigated the immunohistochemical localization of GD2 in the human nervous system. Anti-GD2 MAb (14G2a) reacted with the myelin sheaths in the peripheral nerves as well as with the pituicyte cytoplasm in the posterior lobe of the pituitary gland. We assume that the binding of anti-GD2 MAb to peripheral nerve myelin and the pituicytes in the posterior pituitary causes sensorimotor demyelinating neuropathy and SIADH.

Animals↗
PubMed1997

Dual component in receptive field centre of bipolar cells in carp retina.

Receptive field centre profiles of depolarizing (ON-) and hyperpolarizing (OFF-) bipolar cells in dark adapted carp retina were determined by using a narrow slit of light. The spatial decline of the photoresponse was found to consist of double exponential function with small and large length constants, about 100 microns and 1 mm, respectively. These were only observed in dark adapted retinae where antagonistic surround responses were not observed. These findings suggest dual sites of electrical coupling, one among dendrites and the other among axon terminals. The gap junctional conductance of the axon terminals was estimated to be 100 times larger than that of the dendrites.

Animals↗
PubMed1997

Dopaminergic and cholinergic interaction in cataleptic responses in mice.

The cataleptogenic effects of haloperidol, a dopamine D2 receptor antagonist; SCH23390, a D1 receptor antagonist; physostigmine, a cholinesterase inhibitor; and pilocarpine, a muscarinic M1 receptor agonist, were challenged by pretreatment of mice with SKF38393, a dopamine D1 receptor agonist; apomorphine, a dopamine D1/D2 receptor agonist (mainly D2 receptor); pirenzepine, a muscarinic M1 receptor antagonist; and scopolamine, a muscarinic M1/M2 receptor antagonist. The effect of physostigmine and pilocarpine on haloperidol and SCH23390 cataleptic responses was also examined. Each of the challenging agents blocked one or more of the cataleptogenic agents, but only scopolamine blocked all four. Pirenzepine blocked cataleptic responses induced by SCH23390 and pilocarpine, but not those by haloperidol and physostigmine. The results of this study suggest that the action of physostigmine (endogenous acetylcholine) on M2 receptors might be more potent than that on muscarinic M1 receptors. A further interesting observation was that the haloperidol-induced catalepsy was enhanced by physostigmine pretreatment, but not by pilocarpine pretreatment, whereas the SCH23390-induced catalepsy showed the opposite spectrum of enhancement by the two cholinergic agonists. We conclude that, although the four cataleptogenic agents act via the dopaminergic-cholinergic systems, their pharmacological differences may be due largely to the different receptor subtypes that are involved in the mediation of catalepsy produced by each agent. Thus, dopamine receptors not only influence the cholinergic muscarinic receptors, but muscarinic M1 and M2 receptors also might mediate dopamine D1 and D2 receptor responses, respectively. The results suggest that there are, at the least, relationships between muscarinic M1 receptors and dopaminergic D1 receptors, and between muscarinic M2 receptors and dopaminergic D2 receptors. Dopamine D1 and D2 receptors may interact in a synergistic fashion on dopaminergic systems, but act independently of each other in influencing other system such as cholinergic neurons.

Animals↗
PubMed1997

Increased levels of nitric oxide derivatives in induced sputum in patients with asthma.

BACKGROUND: Nitric oxide (NO) plays an important role as an inflammatory mediator in the airways. However, because direct measurement of endogenous NO has been difficult in vivo, the exact pathologic roles of NO in human airway inflammation have remained unclear. OBJECTIVE: This study was designed to determine whether NO may be harmful by amplifying allergic inflammation in asthmatic airways. METHODS: In this study we examined the concentration of stable end products of NO, nitrite and nitrate, in induced sputum in 18 patients with asthma and 10 normal control subjects and evaluated the relationship between levels of NO derivatives in sputum and cellular and biochemical profiles, the degree of airflow obstruction, and the cytotoxic activities for epithelial cells. RESULTS: The concentration of NO derivatives in induced sputum was significantly higher in patients with asthma than in normal control subjects (1086 +/- 325 mumol/L, 577 +/- 115 mumol/L; p < 0.05). Percentages of eosinophil counts and eosinophil cationic protein levels in sputum were also significantly higher in patients with asthma. Moreover, percentages of eosinophil counts and eosinophil cationic protein levels in sputum in patients with asthma were significantly correlated with the concentration of NO derivatives in sputum (r = 0.63, p < 0.01; r = 0.56, p < 0.05, respectively). In addition, we found that the concentration of NO derivatives in sputum in patients with asthma was significantly correlated with the degree of airflow obstruction (FEV1/forced vital capacity) (r = -0.62, p < 0.01) and with percentages of shedding epithelial cells (r = 0.61, p < 0.01). CONCLUSION: We have shown that a higher concentration of NO derivatives was found in induced sputum of patients with asthma as compared with normal subjects. The clinical implication of our findings is that measurement of NO derivatives in induced sputum may be useful for assessing allergic inflammation in airways.

Adult↗
PubMed1997

Postnatal ontogeny of the thyrotropin-releasing hormone receptor messenger ribonucleic acids in the rat forebrain.

Postnatal developmental change of the thyrotropin-releasing hormone receptors (TRHR) in the rat forebrain was investigated using TRH binding assays and Northern blot analyses from postnatal day 8 to the age of 2 years. TRH binding assays, with [3H]MeHisTRH as the radioactive ligand, demonstrated that the binding capacity in the forebrain was lowest at postnatal day 8 and increased to a maximum level at postnatal day 20. The TRH binding significantly decreased to adult levels between days 20 and 35, and no significant change was observed thereafter. Northern blot analysis, with a 32P-labeled TRHR cRNA probe, revealed that expression of the TRHR gene in the forebrain was not detectable on day 8 after birth, whereas apparent gene expression could be detected in the anterior pituitary. In contrast to the binding capacities, TRHR mRNA levels were very low until postnatal day 20, and increased significantly between days 20 and 35. No significant alteration in mRNA levels was observed after day 35. These results indicated that: (1) TRH binding capacities in the forebrain increased to a maximum levels between the second and third postnatal week and thereafter decreased to adult level, (2) the levels of TRHR mRNA and the TRH-binding capacities did not correlate in that period, suggesting that the TRHR number in the immature forebrain might be regulated by a posttranscriptional mechanism, and (3) expression of the TRHR gene in the forebrain and pituitary seemed to be regulated differentially during development.

Aging↗
PubMed1997

Nitric oxide, 2-amino-4-phosphonobutyric acid and light/dark adaptation modulate short-wavelength-sensitive synaptic transmission to retinal horizontal cells.

Light-induced changes in the input resistance (Rin) of external, luminosity (i.e. H1) type horizontal cell (HC) perikarya were studied by the bridge-balance method in light-adapted and dark-adapted retinae of carp. Changes in input resistance (delta Rin) induced by short-(460 nm) and long-wavelength (674 nm) flashes, adjusted in intensity to elicit equal-amplitude membrane voltage responses (equal-voltage condition), were measured. In light-adapted retinae, long-wavelength stimuli increased Rin consistently; in contrast, the increase was much less with short-wavelength stimuli. This equal-voltage chromatic delta Rin difference was lost in dark-adapted retinae whereby the delta Rin (an increase) became the same for short- and long-wavelengths. The chromatic delta Rin difference could be recovered by light adaptation or application of sodium nitroprusside to the dark-adapted retinae. Conversely, the equal-voltage chromatic delta Rin difference was eliminated by injection of NG-monomethyl-L-arginine into H1HCs of the light-adapted retinae or by treating the retinae with 2-amino-4-phosphonobutyrate (APB). These results suggest that H1HCs of the carp retina possess distinct postsynaptic mechanisms which mediate short- and long-wavelength signal transmission. Furthermore, it appears that the short-wavelength-sensitive pathway is active only during the light-adapted state of the retina. Taken together, therefore, the short-wavelength transmission to H1HCs probably operates on an APB-sensitive glutamate receptor, with nitric oxide as a light-adaptive messenger.

Acclimatization↗