Fibrinogen, treated by thrombin, leads to des-AABB-fibrinogen, while Reptilase-treated fibrinogen leads to des-AA-fibrinogen, where fibrinopeptides A and B are abbreviated as A and B, respectively. Both des-AABB-fibrinogen and des-AA-fibrinogen automatically form gels, abbreviated as fnT and fnR, repectively. Their gel structures, however, are difficult to be distinguished by the electron microscopy. For the purpose to compare the gel formation of both des-AABB-fibrinogen and des-AA-fibrinogen, the kinetic change of the absolute values of complex elasticity,|G*|, in the fibrinogen-fibrin (F-fn) conversion to fnT and fnR was investigated in experimental conditions similar to the physiological ones. Moreover, our rheological study was carried out in conditions such as almost the same turbidimetrical changes were observed between F-fnT and F-fnR in the early stage.
There was observed the most remarkable turbidimetrical change subsequently to an induction period. Then,|G*|was found out to increase rapidly, and approached gradually to a maximum value|G*|_max. In fnT,|G*|_max was much higher than that of fnR. The density of cross-linking in fnT was estimated to be higher by 2.25 times than that in fnR from the plots of|G*|against frequency in quasi-equilibrium state. In addition,|G*|_max of fnR was the same as that of fnT, formed in a half concentration of fibrinogen, indicating that the hydrolysis of fibrinopeptide A against the hydrololysis of both fibrinopeptides A and B contributes to the gel structure approximately in a half ratio. In the logarithmic plots of|G*|against (t-t₀), the values for fnT and fnR were overlayed on a curve in the early stage. That is, the structure of fnT appears to be similar to that of fnR in this stage, taking into consideration the more selective hydrolysis of fibrinopeptide A than fibrinopeptide B from fibrinogen by thrombin in physiological conditions.

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Aim: It is recently stressed that physiological state of blood viscosity plays some important role in the patho-etiology of some cardiovascular diseases. To know the closer relationship between the blood viscosity and the cardiovascular diseases, we carried out this study.
Method and Subjects: We collected 118 patients (53 male, 65 female) who were diagnosed as having hypertension, hyperlipemia and/or cerebral infarction. The following items were examined.
1) Blood viscosity, 2) Plasma viscosity, 3) Hematocrit, 4) Total cholesterol, 5) HDL-cholesterol, 6) Total protein, 7) Triglyceride, 8) Phospholipid, 9) Fibrinogen.
Results and discussion: The blood viscosity showed higher level in 61-80 years-old group. The plasma viscosity and fibrinogen were higher in the patients over 71 years old. It is suggested the fibrinogen content closely relates to plasma viscosity. The effects of some drugs to the blood viscosity were investigated. Among them, one of β-blockers decreased blood viscosity.

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Silkworm (Bombyx mori) blood has a characteristic flow behavior, and it depends on the metaphoresis of silkworm. Silkworm has also interesting biological function, as for example, it makes a cocoon and changes itself to a puppa.
In this paper, effect of the biological function on dispersion state of silkworm blood was studied by cone-plate type viscometer (LS-40), electron microscope, and GC Mass Spectrography. Silkworm blood used throughout this experiment was obtained from different sources of silkworm and different stages in the age of the silkworm. Non-Newtonian flow behavior and viscosity value of various stages and sources at low shear range, and dependence of biological function on viscosity of silkworm blood were observed. The silkworm blood viscosity changes with the change of source and stage of silkworm, because it depends on the facility of aggregate structure formation. It was found that the viscosity of the regular type of silkworm blood increases with age, however, its viscosity during a certain period exhibited the lowest value. These flow properties of silkworm blood depend on the complicated dispersed state of blood cell particles. From the electron microscopic observation, it was shown that the blood cell contained two main particles, one spherical, and another, the fibrous rod form and, these forms become entangled, hence the complicated aggregate structure is formed. This formation change in aggregate structure was observed with the various stages of silkworm age, and various sources of silkworm.

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