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T Asakura

Publications and source records attributed to T Asakura.

At least 469 records · Page 26Linked to original sources
PubMed1976

Kinetic and equilibrium studies of the reactions of heme-substituted horse heart myoglobins with oxygen and carbon monoxide.

In order to study the effects of chemical modifications of the vinyl groups of heme on oxygen and carbon monoxide binding to myoglobin, apomyoglobins from horse heart were reconstituted with six different hemins with various side chains. Laser flash photolysis experiments of these reconstituted myoglobins showed that the combination rate constants for oxygen (k') and carbon monoxide (l') were closely related to the electron-attractive properties of the side chains. The k' values obtained in 0.1 M potassium phosphate buffer, pH 7.0, at 20 degrees were 0.83 (meso-), 2.4 (deutero-), 1.1 (reconstituted proto-), 1.2 (native proto-), 1.5 (2-formyl-4-vinyl-), 1.9 (2-vinyl-4-formyl-), and 2.7 X 10(7) M-1 S-1 (2,4-diformylmyoglobins), and the corresponding l' values were 2.8, 18, 4.8, 5.1, 7.1, 15, and 35 X 10(5) M-1 S-1, respectively. These rate constants tend to increase as the electron-withdrawing power of the side chains increases, indicating that reduced electron density of the iron atom of heme in myoglobin favors the combination reaction for both oxygen and carbon monoxide. Equilibrium constants (L) between carbon monoxide and various myoglobins were also determined by measuring the partition coefficients (M) between oxygen and carbon monoxide for the myoglobins, and were also found to be closely related to the electronic properties (pK3 of porphyrin) of the heme side chains. The equilibrium association constants for carbon monoxide thus obtained increased with a decrease in pK3 value of the porphyrin. This order was completely opposite to the case of the oxygen binding reaction. The dissociation rate constants for oxygen (k) and carbon monoxide (l) were calculated from the equilibrium and the combination rate constants. The dissociation rate constants showed a similar characteristic to the combination rate constants and increased with the increase in electron attractivity of heme side chains. The concomitant increase in both the combination and dissociation rate constants with increase in electronegativity of the iron atom suggests that these reactions have different rate determining steps, although such a reaction process is contradictory to the generally accepted concept that in a reversible reaction, both on and off reactions proceed through the same transition state. In the on reaction sigma bond formation appears to be dominant, while in the off reaction eta bond break-up is more important.

Animals↗
PubMed1976

A morphological study on vascular changes in the surgically resected tissues of temporal lobe epilepsy-with a special reference to the etiology.

(1) Twenty-one out of 23 cases surgically resected specimens of TLE presented the common histological findings; sclerotic changes of the tissues. And the other two cases encountered the small tumors which might be called "cryptic". (2) Since circulatory disturbance is generally accepted to explain the cause of TLE we reexamined vascular behaviors in detail and found the quantitative and qualitative abnormaltities which reached the high rate of 71% (17 out of 21 cases) except two cases of small tumors. Moreover, it is remarkably noteworthy that these vascular changes adjoin the sclerosed parenchymal tissue. (3) It may be said that vascular changes have exerted some influences on the formation of inferomedial temporal sclerosis from the standpoint of the histological findings, though they are alone not fully sufficient to explain the etiology of TLE.

Brain Neoplasms↗
PubMed1976

[Effects of solcoseryl on the cerebral blood flow, intracranial pressure, systemic blood pressure and EEG in acute intracranial hypertensive cats (author's transl)].

The experiment was performed on 86 cases under intraperitoneal pentobarbital anesthesia. One balloon was placed in the extradural space of right frontal region, and the other balloon was placed in the left extradural space and the intracranial pressure was measured. A needle was stereotaxically inserted into the subcortical area in order to measure the cerebral blood flow. Systemic blood pressure was recorded by inserting a catheter into the femoral artery, and electrocorticogram was also recorded. An expanding intracranial lesion was made by inflating the extradural balloon with physiological saline. The animals were arbitrarily divided into two groups.: 1) light or moderate groups which intracranial pressure before the injection of drug was below 400 mmH2O. 2) severe groups above 400 mmH2O. After the maintenance of the pressure, Solcoseryl was infused intravenously. The investigation was focused to observe whether Solcoseryl reveales any potent effect on cerebral blood flow, intracranial pressure, systemic blood pressure and on electroencephalogram in acute intracranial hypertension. Results 1) Intravenous injection of Solcoseryl had the effect of lowering intracranial pressure in the light or moderate and severe groups. Particularly, dose of 80 mg/kg showed the marked effect, though with a rebound phenomenon in the light or moderate groups. Furthermore, the effect was more marked and lasting by drip infusion of Solcoseryl and also by intravenous injection of Solcoseryl after pretreatment with hydrocortisone, and at this time no rebound phenomenon was recognized. 2) Solcoseryl had the effect of increasing the cerebral blood flow accompained with the lowering of intracranial pressure. 3) Systemic blood pressure was transiently lowered by the injection of Solcoseryl 20 mg/kg or 80 mg/kg and recovered immediately. 4) Solcoseryl had no effect on electroencephalogram in the severe groups. Conclusion On the basis of these results, it is rational to conclude that Solcoseryl could be superior agent render to lower intracranial pressure and to improve cerebral blood flow in acute intracranial hypertension.

Actihaemyl↗
PubMed1975

Mechanical precipitation of hemoglobin köln.

Hb Köln (beta 98 Val leads to Met) was found to precipitate rapidly during mechanical shaking. The rate of precipitation of Hb Köln is 5-6 times faster than that of Hb S. The kinetics of precipitation of the patient's hemolysate, which is a mixture of Hb Köln and Hb A, showed a biphasic curve indicating that Hb Köln precipitates independently from Hb A. The instability of Hb Köln may be attributed to the conformational change in the vicinity of heme. The mechanical shaking may be used as a new method for detection and quantitation of hemoglobin Köln and other unstable hemoglobins.

Chemical Precipitation↗
PubMed1975

A rapid test for sickle hemoglobin.

Vigorous shaking of oxygenated sickle hemoglobin (Hb S) in solution causes precipitation of the hemoglobin. This unusual property of Hb S forms the basis of a simple test for the presence of Hb S. Comparison of results of this test with those from cellulose acetate electrophoresis in blood samples from 599 patients showed no false-positive or false-negative results. The group tested included 55 persons with sickling disorders and 47 others with unusual hemoglobin patterns. This test may be used to confirm the presence of Hb S or to establish the diagnosis of sickling disorders rapidly in the clinic or at the bedside.

Anemia, Sickle Cell↗
PubMed1975

Decrease in oxygen affinity of myoglobin by formylation of vinyl groups of heme.

Three kinds of green synthetic myoglobin were prepared by recombination of horse heart apomyoglobin with spirographis (2-formyl-4-vinyl-), isospirographis (2-vinyl-4-formyl-), and 2,4-diformyldeuterohemins. The optical and oxygen binding properties of the reconstituted myoglobins containing two isomeric monoformyl-monovinylhemins were found to be different. The oxygen affinities (P50) of spirographis and 2,4-diformylmyoglobins are 2.7 and 2.8 mm Hg, respectively, at 25 degrees, and about 2.5 times lower than that of native protomyglobin, while that of isospirographis myoglobin is 1.0 mm Hg and is similar to native myoglobin. Spirographis oxymyoglobin has absorption maxima (alpha, beta, and Soret bands) at 601, 556.5, and 435 nm, isospirographis oxymyoglobin at 595, 550, 429 nm, and 2,4-diformyl oxymyoglobin at 603, 563.5, and 447 nm. The optical red shifts as well as the decrease in the oxygen affinities of these myoglobins are attributed mainly to the presence of strongly electron-attractive formyl side chains. Since the free isomers of monoformyl-monovinyl heme have similar properties, the differences observed after recombination with apoprotein must be caused by interactions with apomyoglobins. The degree of such a protein effect may be estimated by comparing the absorption spectra of heme before and after recombination and was found to differ among the various myoglobins. Comparison of the oxygen affinities of the myoglobins taking account of this protein factor showed that the increase in the P50 values are inversely related to that in the pK3 values of the free porphyrins. These results suggest the involvement of pi bonding in determining the oxygen-iron bond strength.

Animals↗
PubMed1975

[A clinical survey of brain abscess (3rd report): special reference to chronological analysis of EEG on brain abscess (author's transl)].

The attention of those concerned with the management of intracranial abscess has been largely directed to a study of the findings in clinicopathological and neuroradiological investigations. Our object, in this communication is to arouse interest in the electroencephalographic survey, especially chronological electroencephalographic study of absecess patients. The clinical material forming the basis of this study is drawn from a series of 46 consecutive cases of intracranial abscess treated, during 3 years, in the neurosurgical department of Tokyo Women's Medical College.

Adolescent↗
PubMed1975

[A giant aneurysm of the internal carotid artery treated by intracranial direct surgery--with a special reference to the anatomical relationship between the cavernous sinus and the internal carotid artery (author's transl)].

There have been a few reports about intracranial giant aneurysms treated by intracranial direct approaches. Especially, for giant aneurysms of the internal carotid artery, direct operation has been thought to be difficult to perform because of the anatomical particularity and the danger of rupture during surgery. So the cervical carotid ligation has frequently been indicated. However, the carotid ligation does not relieve the symptoms caused by the giant aneurysm as an "intracranial mass lesion". The authors have reported here, a cured case of a giant aneurysm of the intracavernous portion of the internal carotid artery, to which, as the first step, ligation of the internal carotid artery in the cervical region was performed, and as the second step, endaneurysmorrhaphy was carried out for the remaining symptoms caused by the "intracranial mass lesion". Furthermore, the surgical techniques for treatment of giant aneurysms of the internal carotid artery were discussed citing literatures, and the authors concluded that the combined operation of carotid ligation and endane-urysmorrhaphy could be effective to giant aneurysms in this region. Meanwhile, a new concept concerning the anatomy of the carotid-cavernous region already proposed by Bedford, was confirmed by our observation at operation. It may be considered that the intracranial direct approach to aneurysms in this region and also to carotid cavernous fistulae should more frequently be indicated than ever performed, according to the new concept of the anatomy in this region.

Adult↗