Biomedical subjects
Publications and source records attributed to K Doi.
Vascular permeability of the stria vascularis was morphologically examined in hydrops animals, using the tracer method of horseradish peroxidase (HRP). The reaction product of HRP was observed in the capillary of the stria vascularis, not outside of it. The finding suggests that the vascular permeability of the stria vascularis is unchanged in Kimura's hydrops model.
Unilateral endolymphatic hydrops was produced in guinea pigs by cauterization of the endolymphatic sac. Measurements of compound action potential (CAP), cochlear microphonics (CM) and negative summating potential (-SP) confirmed endolymphatic hydrops three months after surgery. In both control and hydropic ears, reaction product of HRP was observed only on the perilymphatic surface of the epithelial cells of Reissner's membrane after 10 min perfusion, while it was observed on both the endolymphatic and perilymphatic surfaces after 30 min perfusion. Epithelial tight junctions were not stained and labelled pinocytotic vesicles were observed in the epithelial cells. These findings suggest that the transport of HRP through Reissner's membrane is unchanged in endolymphatic hydrops and that the epithelial junctions are tight regardless of the distension of Reissner's membrane.
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Testes of 8-week-old male Syrian hamsters which were inoculated intraperitoneally with 10(5) plaque-forming units of the D variant of encephalomyocarditis virus (EMC-D) were examined virologically and histologically. Viral replication was detected from 1 day post inoculation (1 DPI), became more prominent 3 DPI, and was no longer demonstrated 7 DPI. The weight of testis decreased in course of time and it was about 2% of that of control 6 weeks post inoculation (6 WPI). Histopathologically, degeneration and/or necrosis of germinal cells and spermatogonia were observed in many seminiferous tubules of all hamsters 3 DPI. At 7 DPI, luminal obstruction by cellular debris and subsequent replacement of them by mesenchymal cells were common in mildly atrophic tubules surrounded with inflammatory cells. Thereafter, atrophy of seminiferous tubules became severer with the lapse of time and, in addition to plasma cell infiltration, apparent increase in the number of Leydig cells was found in the interstices. No regenerative signs of germinal epithelia were detected by 6 WPI. This is the first report of EMC virus-induced orchitis.
Cardiac and pancreatic lesions were observed in guinea pigs infected with 2 variants (B and D) of encephalomyocarditis (EMC) virus. Cardiac changes were characterized by focal myocardial necrosis and subsequent replacement by immature granulation tissue, and the pancreatic ones by vacuolar degeneration of acinar cells. In the electron microscopic examinations, the affected cardiomyocytes showed intracellular oedema, swelling and/or partial destruction of mitochondria, and distortion and disruption of myofibrils. Intracellular vacuolization and dilatation of rough-surfaced endoplasmic reticulum (rER) were conspicuous in the damaged pancreatic acinar cells. In addition, intracisternal granules were found in dilated rER with a high frequency. These changes were common to animals infected with the B and D variants. On the contrary, B cell alterations; i.e. degranulation and degeneration of insulin granules, were detected only in animals infected with the D variant.
A new volatile anesthetic, sevoflurane, is widely used in Japan. We first report a patient who developed liver dysfunction following sevoflurane anesthesia. He had a resection of the bilateral extra toes at the age of eleven months. Although no problems occurred during the operation, he had serious liver dysfunction. Fourteen days after operation, serum GOT was elevated to the maximum of 836U. The pathogenesis is considered to be related to sevoflurane anesthesia, because viral hepatitis was excluded, and sevoflurane is considerably positive in lymphocyte stimulation test in contrast with antibiotics.
It is apparent that digital radiography holds considerable promise. Although there are some immediate advantages to be gained from using digital technology at present, such as more consistent image quality in portable radiography, most of the benefits have not been fully realized. To do so requires a completely integrated digital radiology department using high-resolution video displays throughout the hospital connected to a large digital image archiving system. This concept, referred to as picture archiving and communication systems (PACS), represents the logical culmination of the extensive research that is continuing in this area. Because of the great expense involved, it is likely that the transition from conventional to digital radiography will be evolutionary in most medical centers, with establishment of local PACS networks initially, such as between the intensive care units and the radiology department. At a more basic level, limited digital radiography systems can function in isolation and address specific needs successfully. Although the science of computer-aided diagnosis is at an early stage, it seems likely that the sensitivity and specificity of these programs will continue to improve. Their eventual utility will depend on their accuracy and ease of use. The ultimate goal would be a relatively "transparent" multifaceted program that would screen all radiographs prior to interpretation to provide the radiologist or clinician with diagnostic suggestions and quantitative data. Given the present rate of progress in this area, such a concept is not unrealistic. However, even the most ardent enthusiasts do not envision totally independent computer-based interpretation of radiographic images for some time. Although digital image processing has not greatly improved diagnostic accuracy merely by enhancing the appearance of the radiographs, there are other potential diagnostic advantages in using digital images, such as rapid retrieval of previous examinations and the ability to correlate chest radiographs with CT or MRI studies rapidly on a video display. Direct image correlation with registration and superimposition has been achieved in the case of positron-emission tomography and MRI studies of the brain. For chest radiograph examinations, superimposition and subtraction of earlier radiographs to enhance the detection of interval change is being studied. The question of when digital chest radiography will replace conventional imaging is controversial. In a recent multiauthored review of this subject, it was estimated that digital chest radiography will replace conventional film radiography in at least 50% of large teaching hospitals by the turn of the century.(ABSTRACT TRUNCATED AT 400 WORDS)
We are developing an automated method for determination of quantitative physical measures of lung textures in digital chest radiographs in order to detect and characterize interstitial lung disease. We describe a scheme of our approach for lung texture analysis, an automated classification method for distinction between normal and abnormal lungs with interstitial disease, and the effect of digital parameters on the accuracy of this computerized analysis, as well as applications of this method to the ILO pneumoconioses standard radiographs. The root-mean-square (rms) variation and the first moment of the power spectrum of the lung texture were determined as quantitative texture measures based on a frequently analysis of lung textures, which represent the magnitude and coarseness (or fineness) of the lung textures, respectively. The computerized classification method is based on the analysis of these texture measures and on a data base derived from clinical cases. This classification method includes three independent tests, one for a definitely abnormal focal pattern, one for a relatively localized abnormal pattern, and one for a diffuse abnormal pattern. A comparison of receiver operating characteristic (ROC) curves obtained by radiologists and by means of the computerized classification method indicates that the computerized approach may provide performance similar to human observers in distinguishing lungs with mild interstitial disease from normal lungs. By investigating the effect of digital parameters such as pixel size, ROI size and the number of quantization levels on these texture measures obtained from the lung texture analysis and the performance of this computerized method, we attained a useful guide in the design of this computerized scheme. Texture measures obtained from computer analysis of the ILO pneumoconioses standard radiographs corresponded closely with the ILO classification categories for small opacities, though it was necessary for a qualified radiologist to identify representative areas in each ILO radiograph because of the inhomogeneous distribution of texture patterns in these standard radiographs. Our results suggest strongly that this computerized method can be a valuable aid to radiologists in their assessment of interstitial lung diseases.
As a preliminary step for studying the function and intracellular behavior of the product of the CDC23 gene, a cell cycle gene of Saccharomyces cerevisiae, we cloned the CDC23 gene and determined its nucleotide (nt) sequence. The nt sequence contains an open reading frame (ORF) of 1878 nt coding for a protein of 626 amino acids (aa). The CDC23 gene is expressed as a 2.4- to 2.5-kb major transcript. The putative protein product of the CDC23 gene has a potential Ca2(+)-binding site near its N terminus, and has four contiguous repeats of a consensus sequence consisting of 34 aa near its C terminus. Regions that can be regarded as consisting of repeats of the same consensus sequence were found in the published aa sequences of the products of three other yeast genes.
The actions of excitatory amino acid (EAA) antagonists on synaptic inputs to neurons in the rat medial vestibular nucleus (MVN) from ipsilateral vestibular afferents and vestibular commissures were studied in brain stem slice preparations. Antagonists used were 2-amino-5-phosphonovalerate (APV), a selective antagonist for the N-methyl-D-aspartate (NMDA) type of EAA receptors, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), a selective antagonist for the quisqualate/kainate (non-NMDA) type of EAA receptors and kynurenate (KYNA), a broad spectrum antagonist for the three types of EAA receptors. MVN neurons were classified as having mono- or polysynaptic inputs from vestibular afferents and commissural fibers by calculating synaptic delay. An application of APV through the perfusion medium suppressed 82% of cells activated monosynaptically from commissures, while it suppressed only 9% of cells activated monosynaptically from vestibular afferents. The application of KYNA proved much less selective, suppressing 83% of the former group of cells and 93% of the latter. CNQX suppressed almost all the cells of both groups. The sensitivity of monosynaptic inputs to KYNA, CNQX or APV was not significantly different from that of polysynaptic inputs irrespective of sources of inputs. These results suggest that excitatory synaptic inputs to MVN neurons are mediated mainly through non-NMDA type of EAA receptors from vestibular afferents and through NMDA as well as non-NMDA types of EAA receptors from commissures.
Forskolin, a diterpene extracted from Coleus forskohlii, is potentially an important tool for studying the modulation of ionic currents by cAMP because it stimulates adenylate cyclase in a variety of cells. We studied the effect of forskolin on cochlear potentials and found that its perfusion of the scala vestibuli (SV) to a concentration more than 10(-5) M and the scala tympani (ST) to more than 10(-4) M produced a reversible elevation of the endocochlear potential (EP) in a dose-dependent manner. The cochlear microphonics recorded simultaneously with the EP was not depressed during the EP elevation. A large negative EP was induced by anoxia following the SV perfusion with forskolin (2 X 10(-4) M). The results suggest that the EP elevation produced by forskolin does not result from the decrease in the negative component of EP but from the increase in the positive component of EP.
The concentrations of fluorine (F), sodium (Na), magnesium (Mg), aluminum (Al), potassium (K), phosphorus (P), calcium (Ca), iron (Fe), nickel (Ni), zinc (Zn) and iodine (I) in the hair of 142 hydrofluoric acid (HF) exposed workers and 273 control subjects were analyzed by wavelength dispersive X-ray fluorescence spectrometry. Postshift urine and serum specimens were also collected for the determination of fluoride. To determine whether external contamination influences hair analysis, the control hair samples were kept in the work environment for one week. With the exception of lower K and Fe values, the levels of F and other elements in the hair of HF workers were higher than in the control subjects. The concentrations of F in hair and in postshift urine were in good correlation (r = 0.65). In the hair of HF workers F and Ca, F and Mg, F and P, F and Al were well correlated with each other (r greater than 0.6). F concentration in the hair increased after the sample was retained, however, it decreased to the reference value after washing. The levels of Ca, Mg and other elements did not change during the experiment.
6-Cyano-2,3-dihydroxy-7-nitroquinoxaline (CNQX) is a new, potent and selective competitive antagonist for the non-N-methyl-D-aspartate (non-NMDA) type of excitatory amino acids receptors. We studied the effect of CNQX on the compound auditory nerve action potential (CAP), cochlear microphonics (CM), summating potential (SP) and endocochlear potential (EP). CNQX in doses of 10-20 microM reduced the CAP magnitude and increased the N1 latency without affecting the CM, SP, or EP. Parallel shifts of CAP amplitude- and latency-intensity functions were observed. The CAP suppressed by 10 microM CNQX was completely reversed by a 10-min washout with artificial perilymph. As 10 microM and 20 microM CNQX seem to exert a selective antagonism for non-NMDA receptors, results indicate that non-NMDA receptors play a major role in synaptic transmission from hair cells to auditory afferent nerves.
The arteriovenous pedicle of all known axial-pattern skin flaps enters from the deep aspect and consequently the flap must contain fat and/or muscle and be of considerable thickness. In an attempt to fabricate a thinner axial-pattern flap the femoral artery and vein of rabbits were implanted, in various vascular configurations, directly into the subdermal layer of the skin. Implantation was found to provoke an extensive outgrowth of new vessels from the implanted artery and vein, and the progress and pattern of this neovascularisation was studied by carbon gelatine perfusion and histology. Neovascularisation begins within a few days of implantation and progresses rapidly. By 8 to 12 weeks it is possible to elevate regularly a viable, large skin flap based on the implanted pedicle.
A simple mathematical model of AV conduction block was constructed on the basis of single-cell electrophysiological experiments concerning the rate-dependent property of excitability of the AV nodal cells (the excitability recovery curve, ERC). This ERC was analogous to the phase response curve (PRC) of cardiac pacemaker cells, which the authors had previously used to construct a model of modulated parasystole. Computer simulation was used to reproduce the ERC. The single-cell ERC was then extended to the entire AV node, and this curve was used to formulate a mathematical model of AV conduction block as a nonlinear, first-order difference equation of the successive PR intervals of the ECG. This model predicted a variety of ECG patterns of AV conduction block: normal rhythm, first-degree block, and several second-degree blocks of complex Wenckebach periodicity in relation to the sinus rate and the shape of the ERC. By assuming this model it was possible to identify the underlying ERC of actual ECGs with complex Wenckebach periodicity.
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Endocochlear potential (EP) and cochlear microphonics (CM) were recorded during the perilymphatic perfusion with forskolin known as an adenylate cyclase stimulant. Forskolin produced a reversible EP elevation in a dose-dependent manner. Perfusion with 1,9-dideoxy-forskolin, an analogue of forskolin that does not stimulate adenylate cyclase, had no effect on EP, whereas perfusions with other agents that raise the cAMP-level (IBMX, a phosphodiesterase inhibitor, and dbcAMP) duplicated the effect of forskolin. The vigorous CM during the EP elevation and the large negative EP induced by anoxia superimposed on the elevated EP indicate that the K+ diffusion potential through the hair cell membrane cannot be altered by forskolin. The results suggest that the adenylate cyclase system in the stria vascularis and/or Reissner's membrane may modulate the generation of EP.
A method of evaluating pulmonary ventilation with a 57-cm image intensifier/television (II/TV) digital chest system is reported. With this method, the patient inhales a mixture of xenon and oxygen gases while dynamic imaging of the chest is done. Images of the airways and ventilated portions of the lungs are obtained by subtraction of images acquired before and after the xenon-oxygen mixture is administered. The feasibility of the method was evaluated by studies with xenon-filled tubes, an airway phantom, and a ventilation phantom. The results indicate that tubes larger than 3.2 mm in diameter are detectable at a xenon concentration of 41%, and that gas flow and flow distribution can be examined after image subtraction. If background subtraction is incomplete because of motion, the visibility of small airways is reduced greatly, although unventilated regions can still be delineated. The initial evaluation of this technique included imaging a healthy volunteer during xenon inhalation.