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Biomedical subjects

I Hayakawa

Publications and source records attributed to I Hayakawa.

At least 73 records · Page 4Linked to original sources
PubMed1984

Analysis of 223 ruptured intracranial aneurysms with special reference to rerupture.

A review of 223 patients with ruptured intracranial aneurysms, including 46 with rerupture, showed that the operability rate was higher and the prognosis better in patients with one rupture. Rerupture cases with low Hunt--Hess grades (0--II) had no better prognosis than one-rupture cases of grade IV. The mean interval between first rupture and rerupture was 12 days. Aneurysms located in the vertebrobasilar system showed the highest rate of rerupture. Daughter and bled-shaped aneurysms had a greater tendency to rerupture. The incidence of rerupture was increased in patients with narrowly localized vasospasm and acute hydrocephalus. Time-course studies of factors of the coagulating and fibrinolytic system suggested their usefulness in predicting the occurrence of vasospasm, infarction, and rerupture and the prognosis of patients with ruptured intracranial aneurysms. Patients at high risk for rerupture of aneurysm should undergo early operation.

Adult↗
PubMed1983

A histological and electron-microscopic study of the cell types involved in rejection of skin allografts in ammocoetes.

The rejection of skin allografts by the larval lamprey, Lampetra reissneri, was studied by light- and electron-microscopy, with particular attention to the cell types involved in the reaction. In all allografts, melanophores were destroyed within 20-60 days (the mean survival time, 36 +/- 12 days). Neither the epidermis nor the underlying collagenous lamella was invaded by host cells until the 60th day. A heavy infiltration of host leucocytes was observed in the allografts in melanophore and adipose layers and in the bundles of muscles. Throughout all stages from 10 to 60 days after the grafting, the cells of the polymorphonuclear leucocyte (PMN) series and eosinophilic granulocytes predominated, but macrophages were not observed at any stages examined. Plasma cells occurred occasionally at later stages (40-60 days) of allograft rejection, but lymphocytes were rarely found at any stages of graft rejection. These observations, combined with the recent finding of the antibody-enhanced phagocytic activity of granulocyte-series cells in the lamprey, indicate that PMNs, but not lymphocytes, function as the major effector cells in allograft rejection in this phylogenetically oldest class of contemporary vertebrates.

Animals↗
PubMed1983

[Analysis of 223 cases of intracranial aneurysms--with special reference to re-rupture of the intracranial aneurysms].

Reviewing 223 cases of intracranial ruptured aneurysms including 46 cases of re-ruptured aneurysms, the following results were obtained. 1) The outcome of the re-rupture aneurysms was more miserable than that of the first rupture. Even low grade cases (Hunt and Hess 0-II) of re-rupture showed no better outcome than high grade cases (Hunt and Hess IV) of first rupture. 2) Re-rupture most often occurred on the 12th (11.6 +/- 6.7) day after the first attack of the subarachnoid hemorrhage. Re-rupture more often occurred in the vertebrobasilar system. In the internal carotid artery and its branches, aneurysms with daughter or bleb tended to rupture again. Aneurysms with daughter, regardless of these location, showed greater incidence of re-rupture than those without daughter. Also rupture often occurred in the cases of lower grade with less vasospasm and with the acute hydrocephalus. 3) It was suggested that the sequential changes of some factors of both the coagulating system and fibrinolytic system might forecast the vasospasm, infarction, re-rupture and prognosis of the patient of intracranial ruptured aneurysms. And therefore, in the cases in which re-rupture is likely, operation should be performed as early as possible, except in those showing diffuse vasospasm or clinical down hill course or in grade V.

Adult↗
PubMed1982

[Metallurgical study on Heifetz clip failure (author's transl)].

A metallurgical study on a fractured aneurysm clip (Heifetz) was described. The conclusion can be summarized by the following: 1) Metallurgical data clearly indicate that the mode of failure is intergranular creacking--probably form a stress-corrosion mechanism. 2) Surgically used aneurysm clip is always in corrosive environments form the metallurgical points of view. Apart from inadequate sterilization was well as mishandling, therefore, corrosion of a metal clip is unavoidable. 3) A clip with multiple parts and made from different alloys may have a greater tendency to corrode than a clip of the one-piece variety. In this meaning Yasargil's clips without strut may be most useful.

Corrosion↗