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Biomedical subjects

K Doi

Publications and source records attributed to K Doi.

At least 541 records · Page 30Linked to original sources
PubMed1993

Oral administration of peptides derived from bonito bowels decreases blood pressure in spontaneously hypertensive rats by inhibiting angiotensin converting enzyme.

1. Peptides C111 (Gly-Val-Tyr-Pro-His-Lys) and C112 (Ile-Arg-Pro-Val-Gln), extracted from the autolysis product of bonito liver and intestine, have been shown to inhibit angiotensin converting enzyme (ACE) activity in vitro with IC50s of 1.6 microM and 1.4 microM, respectively. We examined the effects of oral administration of these peptides on blood pressure. 2. Oral administration of these peptides (500 mg kg-1 body weight each) inhibited the pressor effect of intravenously administered angiotensin I in Sprague-Dawley rats. 3. In spontaneously hypertensive rats, oral administration of these peptides (100-200 mg kg-1 body weight) showed depressor effects. 4. These results suggest that the peptides, C111 and C112, are orally effective ACE inhibitors with hypotensive effect.

Administration, Oral↗
PubMed1993

Biphasic disease of central nervous system induced in DBA/2 mice by the D variant of encephalomyocarditis virus (EMC-D).

DBA/2 mice infected with the D variant of encephalomyocarditis virus (EMC-D) (10(1) PFU/head) developed biphasic hind limb paralysis. At 12 days post inoculation (12 DPI), 60% of the infected mice developed hind limb paralysis and two-thirds of them showed recovery by 33 DPI. Thereafter, about 30% of the mice which once showed paralysis developed hind limb paralysis again by 56 DPI. Histopathologically, the spinal cord lesion of paralysed mice was characterized by demyelination associated with infiltration of macrophages in the funiculus lateralis and by degeneration of neurons in the cornu ventrale. Virus antigens were detected in the cytoplasm of degenerated neurons and oligodendrocytes in the demyelinated lesions from 3 to 14 DPI. At 28 DPI, demyelinated lesions reduced in size due to prominent remyelination. At 56 DPI, infiltration of mononuclear cells mainly composed of anti-L3T4-positive (CD4+) T cells were observed in the cornu ventrale of the mice showing recurrence of hind limb paralysis. These results suggested that the early paralysis was mainly due to demyelination in funiculus lateralis caused by EMC-D and macrophages and that the late paralysis was due to degeneration of motor neurons, probably brought about by CD4+ T cells.

Animals↗
PubMed1993

[Emergency surgical salvage for a closing aortic dissection: 2 case reports].

We report here the emergency surgical salvage for closing an aortic dissection in 2 female patients (case 1; 52 years old, case 2; 72 year old). They were admitted to our clinic for severe back pain (case 1) and a loss of consciousness (case 2). Acute aortic dissection (Stanford A type) with cardiac tamponade was confirmed by chest CT, aortography, and cardiac ultrasonography. Diagnosis was determined as a closing aortic dissection from a thrombosed pseudolumen on enhanced chest CT. An emergency operation was performed on the ascending aorta replacement and included resection of the entry port. The postoperative courses were uneventful, except for temporary hemodialysis in case 1. A closing aortic dissection is a new subcategory for an acute aortic dissection. Diagnosis is difficult, but it is regarded as having a good prognosis following timely emergency treatment. However, provided there is no complication, we recommend that surgical treatment should be performed aggressively to avoid rupture and/or cardiac tamponade.

Aged↗
PubMed1993

Large intra-abdominal desmoid tumors in a patient with familial adenomatosis coli: their rapid growth detected by computerized tomography.

A case of familial adenomatosis coli with large intra-abdominal desmoid tumors is described. The patient initially complained of an abdominal mass, which was diagnosed as a desmoid tumor after surgical resection. Further examinations revealed numerous polyps of the colon which were histologically diagnosed as adenomas. Despite intensive medical therapy, the desmoid tumors rapidly increased in size and number, and resulted in abscess and cavity formation that involved the ileum. Although desmoid tumors are classically benign in nature, we consider these tumors to be a therapeutic problem in patients with familial adenomatosis coli.

Abdominal Neoplasms↗
PubMed1993

Lectin histochemical study on the kidney of normal and streptozotocin-induced diabetic hamsters.

Lectin histochemical characteristics of the kidney of normal and streptozotocin (SZ)-induced diabetic APA hamsters were investigated. Paraffin sections of the kidney of animals killed at 1 and 3 months after SZ-injection were stained with the following 10 lectins: PNA, BPA, DBA, SBA, GSA-I, GSA-II, MPA, WGA, UEA-1 and Con A. Renal lectin binding characteristics of normal APA hamsters differed in some aspects from those in other species reported previously. In the kidney of SZ-induced diabetic APA hamsters, binding activities of some lectins increased in the affected Bowman's capsules and glomeruli as well as in degenerated epithelial cells of uriniferous tubules. Among them, GSA-II in particular exhibited strong binding activity to the degenerated epithelial cells of Bowman's capsules, distal convoluted tubules and collecting ducts.

Animals↗
PubMed1992

Archaebacterial lipid models: highly salt-tolerant membranes from 1,2-diphytanylglycero-3-phosphocholine.

1,2-Di(3RS,7R,11R-phytanyl)-sn-glycero-3-phosphocholine and its glycerol epimers were synthesized as model lipids of archaebacterial halophiles. These amphiphiles, upon sonication of aqueous suspensions, gave rise to small unilamellar vesicles (SUV) of 300-800 A in diameter and about 80 A in the membrane thickness. The liposomes were very stable for at least a month even in a highly concentrated suspension or 5 M aqueous NaCl. The vesicles could retain Na+ and Cl- ions as well as 5(6)-carboxyfluorescein in the aqueous interior at temperature as high as 70 degrees C. The liposomes of ordinary diester lipids such as 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and egg-yolk lecithin were less stable and more permeable than those of the diphytanyl lipids.

Archaea↗
PubMed1992

[Potential usefulness of computer-aided diagnosis (CAD) in a mass survey for lung cancer using photo-fluorographic films].

We investigated the potential usefulness of computer-aided diagnosis (CAD) in a mass survey for lung cancer. When the sensitivity of the computer output was adjusted nearly equal to that of the mass survey in our database which contained 198 photofluorographic films, some shadows detected by the computer output were different from those detected by human observers. Therefore, the best estimated sensitivity of an observer using the computer output was equal to or greater than the sensitivity of double reading. It is expected that CAD may have a role in a mass survey for lung cancer using photofluorographic films.

Diagnosis, Computer-Assisted↗
PubMed1992

Immunochemical characterization of the non-NMDA glutamate receptor using subunit-specific antibodies. Evidence for a hetero-oligomeric structure in rat brain.

Antibodies were made to synthetic peptides corresponding to sequences specific to the glutamate receptor (GluR) subunits, GluR1-4. The specificity of the antibodies was established by Western blotting using membranes of simian kidney cells (COS-7) transfected with GluR subunit DNA. Four antibodies were found to be selective for each of the four GluR subunits, and a fifth antibody recognized both GluR2 and 3. All five antibodies immunoadsorbed Triton X-100-solubilized rat brain [3H]AMPA binding activity and labeled an Mr = 108,000 band in samples of rat brain. The structure of the Triton X-100-solubilized GluR was studied using subunit-specific antibodies covalently attached to protein A-agarose and analyzing GluR subunits bound to the antibodies by Western blotting. Each of the four subunit-specific antibodies immunoadsorbed its respective GluR subunit as well as the other three forms of GluR, showing that the detergent solubilized GluR exists as hetero-oligomers composed of two or more of the four subunits. Evidence supporting a similar structure for membrane bound GluR was obtained using synaptic membranes chemically cross-linked with dithiobis(succinimidylpropionate). GluR was immunoaffinity-purified using the GluR2 and 3-selective antibody. This antibody, covalently attached to protein A-agarose, adsorbed 55% of [3H]AMPA binding activity, and after elution with 1 M KSCN, 22-37% of the binding activity was recovered. Analysis of the purified product showed a major immunoreactive band at Mr = 108,000, and silver staining identified the same major band and no additional polypeptides. The GluR receptor complex, therefore, appears to be made up exclusively of GluR1-4. In the purified GluR preparation, in addition to the Mr = 108,000 band, three higher molecular weight immunoreactive components were also detected. These bands migrated at Mr = 325,000, 470,000, and 590,000. Similar sized proteins were seen in the cross-linked synaptic membrane sample, with the Mr = 590,000 component being substantially enriched after cross-linking. The Mr = 590,000 band is the largest component detected, and it has a size consistent with its being a pentamer of the Mr = 108,000 protein.

Amino Acid Sequence↗
PubMed1992

Differential expression of two distinct forms of mRNA encoding members of a dipeptidyl aminopeptidase family.

We have identified two cDNAs encoding dipeptidyl aminopeptidase-like proteins (DPPXs) in both bovine and rat brains that have different N-terminal cytoplasmic domains but share an identical transmembrane domain and a long C-terminal extracellular domain. In both species, one of the cDNAs encodes a protein (designated DPPX-S) of 803 amino acid residues with a short cytoplasmic domain of 32 amino acids, and the other cDNA encodes a protein (designated DPPX-L) with a longer cytoplasmic domain--the bovine cDNA encodes 92 amino acids and the rat cDNA encodes 88 amino acids. The membrane topology of DPPX-S and -L is similar to that of other transmembrane peptidases, and DPPX-S share approximately 30% identity and 50% similarity with reported yeast and rat liver dipeptidyl aminopeptidase amino acid sequences, suggesting that DPPX is a member of the dipeptidyl aminopeptidase family. DPPX-S mRNA is expressed in brain and some peripheral tissues including kidney, ovary, and testis; in contrast, DPPX-L mRNA is expressed almost exclusively in brain. No transcripts for either form are found in heart, liver, or spleen. In situ hybridization studies show that the two transcripts have different distributions in the brain. DPPX-L mRNA is expressed in limited regions of brain with the highest level of expression in the medial habenula. More widespread expression is seen for DPPX-S mRNA. The differential distribution of mRNAs for the DPPX-S and -L suggests that these proteins are involved in the metabolism of certain localized peptides and that the cytoplasmic domain may play a key role in determining the physiological specificity of DPPX.

Amino Acid Sequence↗
PubMed1992

Chemically humanized murine monoclonal antibody against a cell nuclear antigen: usefulness in autoimmune diagnostics.

The cellular nuclear antigen SS-B/La is known to be a major antigenic target to an autoantibody in patients with Sjogren's syndrome and systemic lupus erythematosus. It is useful to detect an anti-SS-B/La antibody from patients' sera in a clinical point of view. We purified SS-B/La from rabbit thymus acetone powder by affinity chromatography with a murine anti-SS-B/La monoclonal antibody (1C3-H7). An enzyme-linked immunosorbent assay method, in which SS-B/La was used to coat a plate, was also successfully established. It is difficult to obtain a large volume of patient's serum with high antibody titer and high specificity as a positive control. We investigated whether or not a positive control from human could be replaced by a murine monoclonal antibody to SS-B/La. The 1C3-H7 was conjugated with a human IgG Fc' fragment using N-gamma-maleimidobutyryloxysuccinimide as a cross-linker. The chemically humanized murine monoclonal antibody (1C3-Fc') was recognized by antiserum specific for human IgG Fc fragment. 1C3-Fc' reacted to SS-B/La but not to other antigens. Furthermore, the titration curve of this conjugate ran parallel with those of patients' sera specific for SS-B/La. It is concluded that a chemically humanized murine monoclonal antibody is useful as a positive control in place of a human patient's serum.

Animals↗
PubMed1992

Diffusion coefficient for O2 in plasma and mitochondrial membranes of rat cardiomyocytes.

Oxygen diffusion in plasma membranes and mitochondrial (Mt) membranes of ventricular myocytes isolated from adult rat hearts was measured using O2-induced fluorescence quenching of pyrene-butyric acid. The diffusion coefficient for oxygen (DO2 in 10(-6).cm2 x s-1) of the plasma membrane was 2.91 +/- 0.05 (37 degrees C) in the control group, which was significantly higher than that of Mt membrane (2.23 +/- 0.11) (P < 0.001). The DO2 of the plasma membrane was reduced to 2.50 +/- 0.08 (P < 0.001) in myocytes isolated from heart after 15 min reperfusion following no-flow ischemia for 30 min, while that of the Mt membrane remained almost unchanged. Administration of hydrogen peroxide and hypochlorous acid to the isolated myocytes also reduced the plasma membrane DO2. The decrease in the plasma membrane DO2 correlated with that in the fraction of rod-shaped myocytes. We conclude that the plasma membrane is more susceptible to reperfusion injury than the Mt membrane, but these membranes do not limit O2 uptake in the heart because of the high absolute values of DO2.

Animals↗
PubMed1992

Embryonic heart rate of the domestic fowl (Gallus domesticus) in a quasiequilibrium state of altered ambient temperatures.

1. The heart rates (fH) of 12-day-old embryos (young), 16- and 18-day-old embryos (late) and of 20-day-old embryos (externally pipped eggs, EP) were measured noninvasively at a temperature of 38 degrees C and after a 5 hr exposure to an ambient temperature (Ta) within the range 34-46 degrees C. 2. All embryos survived the 5 hr exposure to Ta of 42 degrees C. The lethal Ta ranged from 44 degrees C (EP eggs) to 46 degrees C (young embryos). 3. The temperature coefficient (Q10) of fH became smaller than 2 in EP eggs as Ta was decreased or increased from 38 degrees C, implying an incipient homeothermic response of fH.

Animals↗
PubMed1992

A comparison of vascularized and conventional sural nerve grafts.

Long-term results of a randomized series of 27 vascularized and 22 conventional sural nerve grafts in patients with comparable upper extremity injuries are reported. Recovery speed and outcome depended on (1) whether or not there was an overlying skin defect, (2) how the defect was closed, and (3) which nerve was injured and at what level. Generally, a vascularized nerve graft is indicated when the nerve gap is more than 6 cm and is associated with a massive skin defect or the graft is performed after reimplantation. Otherwise, results achieved with a conventional graft are equally good.

Adolescent↗
PubMed1992

Adenylate cyclase modulation of endocochlear potential during suppression of strial Na(+)-K+ ATPase.

Forskolin, an adenylate cyclase activator, produces a reversible elevation of the endocochlear potential (EP) (Doi et al., 1990a). To determine whether strial Na(+)-K+ ATPase activity is essential for the forskolin-dependent EP elevation, we examined, by means of K(+)-selective microelectrodes, the effects of forskolin on the EP and the endolymphatic K+ activity ([K+]) while strial Na(+)-K+ ATPase was suppressed by ouabain. Perilymphatic perfusion with ouabain (10(-3) M) decreased the EP from 78.5 +/- 2.4 mV to -27.6 +/- 2.4 mV (N = 8) at 37.9 +/- 3.7 min after the start of perfusion and decreased the [K+] from 138.7 +/- 5.4 mM to 103.7 +/- 3.7 mM (N = 3). Successive perfusion with forskolin (2 x 10(-4) M) with ouabain (10(-3) M) increased the EP by 15.1 +/- 1.5 mV (N = 8) but did not influence the [K+] decrease from 101 +/- 3.6 mM to 95 +/- 1.3 mM (N = 3). Forskolin (2 x 10(-4) M) with ouabain (10(-3) M) without a preceding ouabain perfusion decreased the EP from 76.2 +/- 2.3 mV to -12.9 +/- 1.8 mV (N = 6) at 65.3 +/- 2.1 min after the start of perfusion. These results indicate that adenylate cyclase can modulate the EP in the absence of strial Na(+)-K+ ATPase activity and that adenylate cyclase activation can attenuate the EP drop induced by strial Na(+)-K+ ATPase suppression.

Adenylyl Cyclases↗
PubMed1992

Evaluation of imaging properties of a laser film digitizer.

In this paper we provide a quantitative assessment of the basic imaging properties of a laser film digitizer. The characteristic curve of the digitizer was determined in terms of the relationship between input optical density and output pixel value. Spatial resolution of the laser digitizer was characterized using the presampling modulation transfer function (MTF), which was measured using a curve fitting technique with an angulated slit. For the noise analysis, we compared the Wiener spectra of uniformly exposed film samples before and after digitization. The effects of different sampling distances and scanning directions were investigated. Our results show that the characteristic curve of the laser digitizer was linear. The presampling MTFs of the digitizer were similar at different sampling distances and were substantially greater in the vertical scanning direction than in the horizontal direction. The noise of the digitized film sample was mainly affected by the presampling MTF and structure noise of the digitizer.

Evaluation Studies as Topic↗
PubMed1992

Computer-aided detection of diffuse liver disease in ultrasound images.

The authors are developing an automated method of determining measures of texture in liver ultrasound images to improve the accuracy of diagnosis of diffuse liver abnormalities. In each digitized image, the background trend of pixel values is estimated to isolate the underlying pattern of liver texture. After correcting for background trend, the root mean square (RMS) variation and the first moment of the power spectrum are calculated; these measures have been applied successfully to texture analysis of digital chest radiographs. Background trend-corrected measurements detected statistically significant differences in digitized ultrasound images of 11 normal and 11 abnormal livers. Without correction for background trend, the measures are unable to distinguish normal from abnormal liver texture. The authors also investigated the effect on the texture measures of varying several ultrasound imaging parameters in normal patients and in an ultrasound phantom.

Adult↗
PubMed1992

Computerized scheme for the detection of pulmonary nodules. A nonlinear filtering technique.

To aid radiologists in the detection of lung cancer, the authors are developing a computer-aided diagnosis system that locates areas suspicious for nodules in digital chest radiographs. The system involves a difference-image approach and various feature-extraction techniques. The authors describe nonlinear filters used in the difference-image approach. A morphological open operation and a ring-shaped median filter are applied in the difference-image step for signal enhancement and signal suppression, respectively. Using 60 clinical chest radiographs, the nonlinear filtering method detected approximately 63% of actual nodules with approximately 19 false-positive results per image. The locations of the false-positive detections, however, usually did not coincide with those from the linear filtering method. Thus, by using a combination of the detections from the two methods, the false-positive rate was reduced to two to three per image at a sensitivity of 60%.

Evaluation Studies as Topic↗