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Biomedical subjects

K Doi

Publications and source records attributed to K Doi.

At least 649 records · Page 36Linked to original sources
PubMed1989

[A comparative study of the depressive effects of halothane and isoflurane on medullary respiratory neurons in cats].

The depressive effects of halothane (H) and isoflurane (I) on the same respiratory neuron were studied in cats. Using a tungsten microelectrode, activities of medullary inspiratory neurons were recorded around nucleus ambiguus. The number of spikes (Spike) of each respiratory cycle and inter-spike interval (ISI) were measured. At 1 MAC, in 9 units out of 11, Spike was significantly fewer with I than with H. In 2 units out of 11, Spike was not significantly different between H and I. These results indicate that each respiratory neuron shows different sensitivity to H and I at 1MAC concentration. With increasing depth of anesthesia, Spike showed a concentration-related depression. During the course of respiratory depression, the spikes were 75.9 (1MAC), 63.3 (1.5MAC), 48.0 (2MAC), 24.2 (2.5MAC), 5.0 (3MAC) with H, and 77.4 (0.5MAC), 51.9 (1MAC), 23.5 (1.5MAC) with I. These spikes were completely depressed at 3.5MAC in H and 2MAC in I. Both H and I increased ISI with increasing depth of anesthesia. The effects of H and I on the phrenic nerve discharges closely resembled their effects on the respiratory neurons. We conclude that the respiratory depression produced by I exceeds that produced by equal MAC of H.

Animals↗
PubMed1989

Effect of hyperglycemia on hepatic extraction of insulin in totally pancreatectomized dogs.

Using the glucose clamp technique, we investigated the effect of blood glucose levels on hepatic extraction of insulin in pancreatectomized dogs. A primed continuous infusion of regular insulin was administered at a rate 1.5 mU/kg body wt./min into the portal or peripheral vein and the blood glucose level was clamped at hyperglycemia (over 200 mg/dl) or euglycemia (below 100 mg/dl) by a variable infusion of glucose through the saphenous or portal vein. Plasma insulin concentrations were measured during portal or peripheral insulin infusion, as were the metabolic clearance rates of insulin during insulin infusion via each route. Hepatic extraction of insulin was calculated from the two metabolic clearance rates using the insulin kinetic model (Pilo' method). Hepatic extraction of insulin during the hyperglycemic clamp was 45.8 +/- 2.5%, significantly higher than that during the euglycemic clamp (35.7 +/- 2.8%: p less than 0.01). When glucose was infused into the portal instead of the peripheral vein during the euglycemic clamp, hepatic extraction of insulin increased (44.7 +/- 3.4 vs 37.6 +/- 2.9%: p less than 0.05). It was concluded that hyperglycemia increases the hepatic extraction of insulin. Moreover, portal hyperglycemia during the euglycemic clamp also increases the hepatic extraction of insulin. It is suggested that portal glucose concentration may affect the hepatic extraction of insulin.

Animals↗
PubMed1989

Rapid development of renal lesions in diabetic DBA mice infected with the D-variant of encephalomyocarditis virus (EMC-D).

Marked hyperglycaemia and renal lesions developed rapidly in DBA mice infected with 10 plaque-forming units of the D-variant of encephalomyocarditis virus (EMC-D). Renal alterations were demonstrated in the glomeruli, tubular epithelium and small vessels 2 months after infection. Glomerular changes were characterized by mesangial thickening due to an increase of basement membrane-like material in the mesangial matrix. Nodular glomerular lesions were commonly observed 3 months after infection, whereas distinct thickening of the glomerular basement membrane was rarely seen. Besides these glomerular changes, glycogen inclusions in the distal tubular epithelium and medial degeneration in the arterioles were also noticed. The EMC-D-infected DBA mouse appears to be a useful experimental model for the study of human diabetic nephropathy.

Animals↗
PubMed1989

[A case of asbestosis complicated with double cancer of the stomach and colon].

A case of a double cancer, a stomach and a colon cancer, in a 84-year-old man is reported. The patient had an occupational history of asbestos exposure while working at two shipyards. His chest X-ray revealed typical, pleural plaque with calcification. Further, a significant number of asbestos bodies in his autopsied lung tissue was detected. In spite of failure to detect asbestos bodies in the stomach and the colon, our findings suggest that these two cancers may have been induced by asbestos exposure.

Adenocarcinoma↗
PubMed1988

The binding of molybdate to uteroferrin. Hyperfine interactions of the binuclear center with 95Mo, 1H, and 2H.

Uteroferrin, an acid phosphatase with a spin-coupled and redox-active binuclear iron center, is paramagnetic in its pink, enzymatically active, mixed-valence (S = 1/2) state. Phosphate, a product and inhibitor of the enzymatic activity of uteroferrin, converts the pink, EPR-active form of the protein to a purple, EPR-silent species. In contrast, molybdate, a tetrahedral oxyanion analog of phosphate, transforms the EPR spectrum of uteroferrin from a rhombic to an axial form. With both electron spin echo envelope modulation (ESEEM) and electron nuclear double resonance (ENDOR) spectroscopies, we observe a hyperfine interaction of [95Mo]molybdate with the S = 1/2, Fe(II)-Fe(III) center of the protein. A pair of 95Mo resonances centered at the 95Mo Larmor frequency at the applied magnetic field and separated by a hyperfine coupling constant of 1.2 MHz is evident. Therefore, a single monomeric species of molybdate is close to, and likely a ligand of, the binuclear cluster. 1H ENDOR studies on uteroferrin reveal at least six sets of lines mirrored about the 1H Larmor frequency. Two pairs of these lines become reduced in intensity when the protein is exchanged against D2O. Moreover, ESEEM and 2H ENDOR spectra display resonances at the 2H Larmor frequency. Therefore, the metal-binding region of the protein is accessible to solvent. Additional deuterium lines observable by ESEEM spectroscopy provide evidence for a population of strongly coupled, readily exchangeable protons associated with the binuclear center. The measured hyperfine coupling constants for these deuterons are orientation-dependent with splittings of nearly 4 MHz at g3 = 1.59 and less than 1 MHz at g1 = 1.94. In the presence of molybdate, ESEEM spectra of D2O-exchanged samples reveal a resonance at the 2H Larmor frequency, with no evidence of spectral components due to strongly coupled deuterons. 1H ENDOR studies of the uteroferrin-molybdate complex show at least seven pairs of lines, mirrored about the 1H Larmor frequency, of which one pair becomes attenuated in amplitude upon deuteration. The active site thus remains accessible to solvent in the presence of molybdate.

Acid Phosphatase↗
PubMed1988

Morphological study of nervous system in Vacor-induced diabetic rats.

Patients with Vacor diabetes mellitus frequently developed diabetic ketoacidosis and neuropathy in the early stage of the disease; however, the mechanism of the development of diabetes and its neurologic complications is not known. In this study, oral administration of 100 mg Vacor/kg of body weight was used in Wistar male rats. The rats were sacrificed 6 h after administration to avoid natural expiration. Light microscopy revealed focal hemorrhage and edematous change in the periventricular area of the brain, scattered hemorrhage in the posterior and anterior horns, spongy degeneration and demyelinization in th fasciculus gracilis and cuneatus of the white matter, early degenerative changes in the sciatic nerve, and no change of the vagus. Electron microscopy showed necrosis of the axon, myelin sheaths and glia cells in the spinal cord, while the organelles of the peripheral nerves were unchanged. These findings indicate that Vacor produces various neurotoxicities in the acute toxic phase.

Animals↗
PubMed1988

Histochemical characteristics of glycoproteins in the bile duct system of mice immunized with swine serum.

The bile duct system of BALB/c and DDY mice, which were immunized with swine serum (SS) or not, was examined histochemically. Biliary epithelial cells of the SS-treated BALB/c mice, which were positively stained with periodic acid-Schiff (PAS) and had binding sites of Dolichos biflorus (DBA), were thought to secrete neutral glycoproteins with terminal N-acetyl-D-galactosamine residues. Those of the SS-treated DDY mice were however negatively or weakly stained with any histochemical stainings. On the other hand, glandular epithelial cells of the SS-treated mice of both strains, which were positively stained with high iron diamine-alcian blue (HID-AB) and had binding sites of DBA, Griffonia simplicifolia-II (GS-II), Ulex europaeus-I (UEA-I), and Triticum vulgaris (WGA), were thought to secrete glycoproteins with terminal sialic acid residues. Biliary and glandular epithelial cells of the normal mice contained only a small amount of glycoproteins showing similar histochemical characteristics to those in the SS-treated BALB/c mice. BALB/c mice immunized with SS were thought to be very useful for the investigation of production and secretion of glycoproteins in the bile duct system as well as being good model of bile duct disease.

Animals↗
PubMed1988

Digital image processing of periapical radiographs.

Periapical radiographs were processed digitally with an image-processing system. In processed images obtained with an aperture of 100 X 100 micron 2, some radiographic information was lost because the aperture was too large for processing of periapical radiographs. Greater noise and more artifacts were also present and occasionally disturbed the interpretation. Therefore, we conclude that digital image processing of periapical radiographs is not always useful. Improvement of contrast was obtained, however, and this seemed to be effective for low-contrast radiographs.

Humans↗
PubMed1988

Prevalence of the coexistence of left ventricular false tendons and premature ventricular complexes in apparently healthy subjects: a prospective study in the general population.

The prevalence of left ventricular false tendons, premature ventricular complexes and their coexistence was evaluated prospectively in 187 healthy company workers aged 21 to 50 (mean 36) years. False tendons were demonstrated echocardiographically in 133 (71%). Eight subjects were withdrawn from the study because of silent mitral valve prolapse. In these 179 healthy subjects, false tendons were detected in 127 (71%) and premature ventricular complexes in 48 (27%). Their coexistence was observed in 40, which showed a significant correlation (p less than 0.05) of false tendons and premature ventricular complexes. In seven of the eight subjects without false tendons, premature ventricular complexes were uniform and infrequent (mean 3 beats/24 h). In the 40 subjects with false tendons, premature ventricular complexes were uniform in 29, multiform in 6 and repetitive in 5, and the mean frequency was 96 beats/24 h. Correlation of premature ventricular complexes with the type of false tendons showed that premature ventricular complexes were significantly associated with thick (greater than or equal to 2 mm) and longitudinal tendons (p less than 0.005). Although it is not certain that left ventricular false tendons are arrhythmogenic, the prevalence of the coexistence of left ventricular false tendons and premature ventricular complexes in the general population, and the special relation between the frequency and the form of premature ventricular complexes and the type of false tendons, suggests that false tendons may play an etiologic role in the genesis of premature ventricular complexes in apparently healthy subjects.

Adult↗
PubMed1988

Accurate analysis of blood vessel sizes and stenotic lesions using stereoscopic DSA system.

We have developed a technique to determine accurately the magnification factor and three-dimensional orientation of a vessel segment from a stereoscopic pair of digital subtraction angiograms (DSA). Our DSA system includes a stereoscopic x-ray tube with a 25-mm focal spot shift. The magnification and orientation of a selected vessel segment are determined from the distance and direction of the focal spot shift and the stereoscopic discrepancy in image positions for that segment. Our results indicate that the accuracies of determining the magnification and orientation are less than 1% and approximately 5 degrees, respectively. After the magnification and orientation are determined accurately, an iterative deconvolution technique for the measurement of vessel image size is applied to the selected vessel segment. This iterative deconvolution technique provides the best estimate of vessel image size by taking into account the unsharpness of the digital system. With this technique, the vessel image size can be determined to an accuracy of approximately 1.0 mm, which corresponds to one third the pixel size of our DSA system. Information derived from stereoscopic analysis and iterative deconvolution thus allows accurate calculation of actual vascular dimensions from DSA images.

Angiography↗
PubMed1988

Anterior cervical fusion using the free vascularized fibular graft.

A free vascularized fibular graft with microvascular anastomoses was applied to six clinical cases of anterior cervical fusion for cervical spondylosis with myelopathy (two patients) and ossification of the posterior longitudinal ligament with myelopathy in four. The numbers of levels fused were three in five patients, and two in one. Their follow-up period ranged from 14 to 42 months (mean, 26 months). Union of the graft occurred between 2.5 and 5 months (mean, 3.4 months) postoperatively. There were no nonunions nor any serious complications. This technique is indicated for multilevel intervertebral fusion in which the nonunion or delayed union rate with conventional bone grafting may be high.

Cervical Vertebrae↗
PubMed1988

Digital chest radiography: effect on diagnostic accuracy of hard copy, conventional video, and reversed gray scale video display formats.

Observer performance tests were conducted to compare the effects on diagnostic accuracy of hard copy (film) versus video display and to determine the diagnostic merits of conventional negative ("white bone") versus positive ("black bone") video displays. Subjective preferences were elicited from each observer for each display modality, and diagnostic accuracy was determined with receiver operating characteristic analysis. Digitized chest radiographs were used, including normal and abnormal cases with a variety of subtle abnormalities. The hard copy was printed with a 1,024 X 1,024-matrix by a high-quality drum scanner in conventional white bone format only. The video images were displayed on a 1,023-line monitor (30 Hz, interlaced) in both white bone and black bone formats with fixed window and brightness settings. Most observers preferred hard copy to video, but preferences were sharply divided between white bone and black bone video. Diagnostic accuracy was significantly greater with hard copy than with video display, and the conventional white bone format was significantly superior in accuracy to the black bone display.

Computer Systems↗