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Biomedical subjects

K Nakai

Publications and source records attributed to K Nakai.

At least 289 records · Page 16Linked to original sources
PubMed1989

Influence of food on bioavailability from two controlled-release granules of theophylline.

The bioavailability and absorption pattern of theophylline from Theolong granule and Theodur-G were studied in five healthy volunteers both in fasting conditions and after taking two different meals. In all the subjects, no dose-dumping effect was observed with a standard- or a fat-rich breakfast on these preparations. Postprandial administration delayed the absorption of theophylline and a fat-rich breakfast significantly reduced the area under the curve (AUC0-26) for both preparations. The mean AUC decreased by 14.0% for the former and 19.7% for the latter when the fat-rich breakfast was administered. Intake of a standard breakfast resulted in a decrease in the AUC0-26 by 10.6% for Theolong granules but there was little effect observed with the Theodur-G granules.

Adult↗
PubMed1989

Peripheral T-cell lymphomas. Immunologic and enzyme histochemical analysis of 15 cases.

Fifteen cases of peripheral T-cell lymphoma were studied to evaluate the respective properties of various histologic types using enzyme histochemical and ultrastructural examinations in addition to immunological methods. Eleven cases in an ATLA-negative group manifested various histologic patterns such as IBL-like, pleomorphic and Lennert's lymphomas in comparison with the relatively monomorphic proliferation of neoplastic lymphoid cells in the 4 ATLA-positive cases. The presence of neoplastic clear cells is characteristic of peripheral T-cell malignancies, and is likely to be found in CD4+ lymphomas. There is an occasional reaction of epithelioid histiocytes and plasma cells with eosinophils, the former being designated Lennert's lymphoma and the latter IBL-like T-cell lymphoma. Immunological examination revealed four immunophenotypic patterns: (1) CD2+3+4+8-, (2) CD2+3-4+8-, (3) CD2+3+4-8+, and (4) CD2+3+4+8+, but did not provide information concerning the intimate relationship between histologic types and immuno-phenotypes. beta-Glucuronidase reactivity, however, contributed to the distinction between helper and suppressor T-cell malignancies, suggesting its usefulness for distinguishing these two cell types and their malignant counterparts.

Adult↗
PubMed1989

Novel preparation of zein microspheres conjugated with PS-K available for cancer immunotherapy.

Microspheres which entrapped PS-K were prepared using Zein as a carrier matrix by a one-step or two-step process in dimethyl sulfoxide-H2O media. Microspheres prepared by the latter process provided satisfactory recovery and uptake of PS-K. Use of a catalytic amount of dl-camphorsulfonic acid, glutaraldehyde and rapid addition of aqueous solution of polyvinylpyrrolidone into the reaction media are crucial for the preparation of fine and mono-dispersed microspheres. The release rate of PS-K could be controlled by altering the ratio of PS-K to Zein and the conditions of the medium. In the presence of actinase E, drug release was considerably increased to 70-80% after 24 h incubation. Sonication of the aggregated microspheres readily yielded a mono-dispersed preparation with a particle diameter of less than 1 micron, which would be a suitable size for phagocytosis by macrophages.

Chemical Phenomena↗
PubMed1989

[A new pocket-type flicker apparatus].

A small, light and inexpensive pocket flicker (P.F.) apparatus for measuring fatigue was designed, fabricated and tested. The apparatus, being composed of a light emitting diode and a variable resistor with a scale, is so compact that it can be carried in a shirt pocket. Thus, critical fusion frequency (CFF) values can be easily determined at a working place and the load involved is small when compared to other physical fatigue measurements and earlier CFF apparatuses. Moreover, the apparatus is so inexpensive that it can be widely used. To compare the performance of the P.F. apparatus with earlier apparatuses, the following experiments were performed. CFF values were measured at the same time with the pocket type apparatus, blinking type apparatus and sector type apparatus and the results were compared. The subjects were 13 males and 5 females with their age ranging from 21 to 52 years. The total number of measurements was 132. The CFF values measured with these three apparatuses showed a significant correlation. The correlation coefficient between the CFF values measured with the sector type apparatus and blinking type apparatus was high, but the slope of the regression line was not one. Hence, in comparing the values measured with another apparatus, we should be aware of the differences between these data. The correlation coefficients between the CFF values measured with P.F. apparatus and with sector type apparatus or blinking type apparatus were not higher than those between the CFF values measured with sector type apparatus and blinking type apparatus.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Phosphofructokinase in rabbit dental pulp is less sensitive to ATP inhibition.

ATP-dependent profiles of phosphofructokinase (PFK) activity were determined in both crude and Sephadex G-25-filtered fractions from rabbit dental pulp. ATP had a dual effect on PFK as an activator and an inhibitor, according to its concentration. Gel-filtered PFK showed a similar profile to that of crude PFK, indicating a lack of low-molecular-weight effector(s) for PFK in rabbit dental pulp. For complete inhibition of the PFK in rabbit dental pulp, 5 mM ATP was required. This level of ATP is much higher than that required for other typical isozymes of PFK from liver, skeletal muscle or brain. It is postulated that differences in the properties of PFK isozymes are due not only to the subunit structure but also to the presence of other effectors.

Adenosine Triphosphate↗
PubMed1989

[Evaluation of exercise thallium-201 myocardial single photon emission computed tomography in silent myocardial ischemia].

To evaluate the diagnostic significance of exercise Tl-201 myocardial SPECT in silent myocardial ischemia, 41 patients with angiographically-proven coronary artery disease (27 effort angina, 14 post-infarction angina) were tested using this method. Double product (blood pressure x heart rate) during exercise was used as a hemodynamic parameter. Thirty-two projections were obtained throughout 180 degrees by a rotating gamma camera, immediately, and four hours after exercise. Myocardial Tl-201 washout rate of the entire left ventricle was presented in two-dimensional polar function maps. Normal lower limit of myocardial Tl-201 washout rate was defined as mean-2SD of normals, and the region with a washout rate lower than normal was defined as an ischemic region. The location of myocardial ischemia was visually determined using a Bull's eye polar map. The ischemic size was quantified by the defect volume ratio (ratio of the ischemic myocardium to total myocardium). Coronary lesions were quantitatively assessed by the Pujadas score using coronary angiography. Results were as follows: There was no significant difference between painful myocardial ischemia and silent myocardial ischemia according to double product and the Pujadas scores. In most silent ischemia, the region of the reduced washout rate was in the inferior or lateral area of the Bull's eye polar map, whereas it was in the anterior area in painful ischemia. The defect volume ratio indicating the extent of ischemia was smaller in silent ischemia than in painful ischemia. In conclusion, the ischemic location and size may be contributing factors in silent myocardial ischemia.

Exercise Test↗
PubMed1989

[Osteoblastic skull metastasis of lung cancer].

A case of osteoblastic skull metastasis of lung cancer is reported. A 56-year-old female patient was admitted to our hospital with complaints of headache and tumor of the right parietal bone. A plain skull X-ray showed hyperostotic feature of the right parietal bone. CT scan displayed that right parietal bone became thick and osteoblastic. Soft tissue was shown in the hyperostotic bone under MRI. An external carotid angiogram showed that the skull tumor was fed by the middle meningeal artery. The skull tumor and 2 solid intracerebral tumors were extirpated. Histological examination revealed adenocarcinoma in the skull and intracerebral lesions. The present case indicates that osteoblastic stimulating factor may be secreted by lung cancer.

Adenocarcinoma↗
PubMed1989

Vascular "sphincter" and microangioarchitecture in the central nervous system: constriction of intraparenchymal blood vessels following a treatment of vasoconstrictive neurotransmitter.

The site of action of neuropeptide Y (NPY), a potent vasoconstrictive neurotransmitter, on the intraparenchymal blood vessels in the rat parietal cortex was demonstrated using a corrosion cast technique with scanning electron microscopy. Our observations were confined to the cortical area where the regional cerebral blood flow (rCBF) had been reduced significantly by in situ application of NPY. A striking finding in that area was the diffuse narrowing of the perforating arteries in the upper cortical layers. Ring-like compressions on the corrosion casts, presumably formed by active vascular sphincters along the arteries, capillaries and venules within the brain parenchyma, seemed to be more prominent in the perforating arteries of the NPY-treated cortex as compared with those of control cortex. We conclude that NPY-containing nerve fibers along the parenchymal blood vessels may take part in regulating the rCBF primarily by reducing the caliber of the proximal perforating arteries.

Animals↗
PubMed1988

Immunohistochemical demonstration of vasopressin nerve fibers in the cerebral artery.

Vasopressin-immunoreactive nerve fibers were demonstrated in the cerebral pial arteries by peroxidase immunohistochemistry. In the large pial artery (proximal part of the middle cerebral artery), they ran longitudinally to the long axis of the vessel. They ran in a spiral pattern in the distal part of the middle cerebral artery. Even in small arteries, vasopressin nerve fibers were found arranged in a longitudinal fashion. The present morphological data suggest that vasopressin nerve fibers in the cerebral artery may play a role in cerebral circulation.

Animals↗
PubMed1988

Prediction of in-vivo modification sites of proteins from their primary structures.

In order to make better use of the information contained in rapidly expanding amino acid sequence data, a new method to predict various modification sites of proteins from their primary structures is presented. It is also applicable to the prediction of other functional sites in proteins. Here we show the examples of N-glycosylation and serine/threonine phosphorylation sites. The method is essentially an elaboration of consensus sequence pattern matching based on stepwise discriminant analysis. The occurring amino acids near a potential modification site are represented by six numerical values which reflect various properties of amino acids. Longer-range effects around these sites are also considered. The stepwise procedure enabled us to automatically select effective features for discrimination. A computer program with our method first identifies potential modification sites by a sequence pattern, NX(S/T) for N-glycosylation or (S/T) for phosphorylation, and then decides by discriminant analysis whether a potential site is likely to be a true modification site. The prediction accuracy in the second step of discrimination was about 60% for glycosylation sites and about 80% for phosphorylation sites.

Amino Acid Sequence↗
PubMed1988

Cluster analysis of amino acid indices for prediction of protein structure and function.

The relationship among 222 published indices representing various physicochemical and biochemical properties of amino acid residues has been investigated by hierarchical cluster analysis. The clustering result is illustrated by the minimum spanning tree, which is conveniently divided into four regions: alpha and turn propensities, beta propensity, hydrophobicity and other physicochemical properties including, among others, bulkiness of amino acid residues. In addition, several subclasses of hydrophobicity scales have been identified: preference of inside and outside, accessible surface area, surrounding hydrophobicity and other mostly experimental scales including transfer free energy, partition coefficients, HPLC parameters and polarity. Representative amino acid indices are identified in each of these groups. The collection of amino acid indices is a useful resource for empirical analyses correlating sequence information with structural and functional properties of proteins. As an example, the indices that best reproduce the amino acid mutation data matrix are searched against this collection.

Amino Acids↗
PubMed1988

Effects of furosemide on the resting membrane potentials and the transmitter-induced responses of the Aplysia ganglion cells.

Effects of Furosemide (FM) on the ionic channels in the ganglion cells of Aplysia were investigated using a conventional electrophysiological method. Application of 1 mM FM for 30 min did not alter the resting membrane potential or conductance. Na+-dependent responses to acetylcholine (ACh) were slightly depressed but Cl--dependent responses to ACh and gamma-aminobutyric acid (GABA) were markedly depressed by FM. On the other hand, K+-dependent responses to ACh and dopamine (DA), and cyclic adenosine-3', 5' monophosphate (cAMP)-dependent response to DA were not appreciably altered by 1 mM FM. The depressing effects of FM on both Na+- and Cl--dependent responses were due to the non-competitive inhibition of their receptor activities. It was concluded that 1 mM FM can change neither Na+-K+-pump nor Cl--pump mechanisms in the ganglion cells of Aplysia, but it depresses the receptor-operated Na+-and Cl--channel activities, the greater effect on the open Cl--channels. In addition, it was postulated that FM effect may be highly specific to the open state of Cl--channels, regardless of whether the membrane is excitable or not.

Acetylcholine↗
PubMed1988

Ex-vivo perfusion of surgically removed organs.

Surgically removed organs were perfused with oxygenated perfluorochemical blood substitute(FDA-O2). The perfusion was carried out using resected mouse liver. ATP level of perfused liver was remaining normal until 80 min. ATP peak disappeared when perfusion was discontinued, and it reappeared on reperfusion. No significant ischemic changes were demonstrated. Ex-vivo autoradiogram successfully labelled the S phase cells in various organs and various diseases. The absorptive study is also performed. Ex-vivo organ perfusion with FDA-O2 is able to keep the resected human organs viable, and is valuable new method to analyze the function and histogenesis of pathology.

Adenosine Triphosphate↗
PubMed1988

Autotransplantation of the superior cervical ganglion into the brain. A possible therapy for Parkinson's disease.

The superior cervical ganglion (SCG) of rats was transplanted into their own parietal cortex. Four weeks after implantation, catecholamine histofluorescence revealed many transplanted catecholamine cells in the cortex. However, no fibers extended from the transplanted tissue to the cerebral cortex. In a second group of rats which had been pretreated with 6-hydroxydopamine (a specific neurotoxin to the catecholamine neuron), some showed extension of catecholamine fibers to the cerebral cortex. To simulate an animal model of Parkinson's disease, MPTP (1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine) was administered to five monkeys. Two weeks after MPTP administration, dopamine terminals in the caudate nucleus disappeared. After autotransplantation of the SCG into the caudate nucleus of these monkeys, many of the transplanted SCG cells extended axons beyond the graft into the caudate nucleus. These results show that transplanted SCG cells survived well in the brain. Under special circumstances, such as a shortage of catecholamine in the brain, implanted SCG cells extended their axons into the brain. It is suggested that autotransplantation of SCG grafts may be a new therapy for Parkinson's disease.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗