Biomedical subjects
Publications and source records attributed to H Ohkuma.
Explore the source record for details and available documents.
Posterior fossa subdural hematoma in neonates caused by birth trauma is rare; only 30 clinical cases can be found in the literature so far. Here we experience two similar cases and review that literature. Case #1 is that of a full-term female born in the pelvic position. At 21 hours after birth she developed convulsions and a CT scan revealed a high-density area, mainly in the right posterior fossa. On the fourth day, a right suboccipital craniectomy was performed and about 15 ml of hematoma was removed. At present her mental and somatic development is appropriate for her age (5 months), despite the fact that moderate brain atrophy was seen in the CT scan taken at 4 months. Case #2 is that of a full-term female also born in the pelvic position. At 38 hours she became convulsive and opisthotonic; a CT scan revealed a high-density area in the posterior fossa. No neurological abnormality was seen thereafter, however, and she was treated conservatively. On the 18th day, the high-density area in the CT scan had almost disappeared. In the CT scan taken at 6 months moderate brain atrophy was seen, but at the present age of two she evidences quite normal development both mentally and somatically. These cases lead us to emphasize the importance of prompt diagnosis followed by removal of hematoma, and the usefulness of CT scan as a diagnostic method in clinical manifestations of this sort.
Explore the source record for details and available documents.
An intraocular cannula system for chronic drug delivery was designed and tested in rabbits. The cannula was inserted through the pars plana and the tip positioned in the vitreous cavity (distal tip) in a site close to the retinal area of interest. The cannula was stabilized by a silicone plate that was sutured to the sclera. The proximal end of the cannula was attached to a larger diameter silicone tubing which served as a connector to the reservoir for chronic drug delivery. Rabbit eyes with implanted cannulas were followed clinically and electrophysiologically for up to one and a half years. They showed almost no adverse effects as a result of the implantation and cannula patency was demonstrated by the injection of sodium fluorescein through the cannula at various times following surgery. We believe that the implanted intraocular cannula, which allows chronic drug delivery, will be a valuable asset for research and possibly clinical studies.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Structures of chicamycins A and B have been determined from a series of chemical degradation studies coupled with spectroscopic analysis. Chicamycin A is 2(S),11(R), 11a (S)-1,2,3,10, 11, 11a -hexahydro-2,8-dihydroxy-7,11-dimethoxy-5H-pyrrolo-[2,1-c] [1,4]-benzodiazepin-5-one, and chicamycin B is 2(S), 11a (S)-1,2,3, 11a -tetrahydro-2,8-dihydroxy-7 -methoxy-5H-pyrrolo-[2,1-c][1,4]-benzodiazepin-5-one which is the demethanol form of chicamycin A. The structure of chicamycin B is closely related to that of neothramycin , differing only in the position of a hydroxyl substituent on the pyrrolidine ring.
A method was established for chronic drug delivery into the vitreous of the rabbit eye. A cannula was inserted into the eye through the pars plana. A silicone plate controlled the intraocular location of the tip of the cannula; this plate also served as an anchor plate to the sclera. The distal end of the cannula was attached via a larger diameter silicone tubing to an implanted osmotic mini-pump. Cannulas remained patent and there was almost no evidence of ocular trauma after one year follow-up. This method thus has a potential use for experimental studies involving chronic application of drugs.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The clinical appearance, fine structure, and permeability to horseradish peroxidase and fluorescein of subretinal neovascularization (SRN) in monkeys was correlated at various stages of vessel development: early (active leaking), intermediate (slightly leaking), and regressive (nonleaking). The degree of SRN permeability correlated well with the presence of endothelial cell fenestrations. The substantial changes in the fine structure and permeability of SRN during maturation can account for the different clinical manifestations. It is thus apparent that the time of morphologic correlation must be considered when studying a dynamic evolving process, such as SRN.
The origin, course, and pattern of experimental subretinal neovascularization (SRN) in monkeys were studied with scanning electron microscopy (SEM) of Mercox preparations of the choroidal vascular bed. This technique allowed visualization of the entire circulation of the SRN lesion from both the retinal and scleral aspects. The SEM data is comparable to that of fluorescein angiography, but provides details not detectable by angiography. The afferent arteriole was traced back to the posterior ciliary artery of origin. In the early stages, the efferent vessels appeared to connect with the choriocapillaris; whereas later the efferent vessels connected directly to the choroidal venous system. The study of such plastic casts enables more accurate assessment of some aspects of the vascular architecture of the SRN frond.
Experimental subretinal neovascularization (SRN) was produced in rhesus monkeys by laser burn and its vascular casts were examined with the scanning electron microscope (SEM). The results showed a vascular pattern similar to that seen in fluorescein angiography, but provided a three-dimensional vascular architecture, which is not detectable by angiography. The SRN represents an ingrowth of new vessels into the subretinal space from the choroid through each burn site. Special attention was given to the afferent and efferent vessels of the SRN frond. The frond was supplied by the choroidal arteriole and the routes of egress from the frond to the choriocapillaris were observed. These observations suggest the uniformity of this experimental SRN, i.e., arteriolar supply to the frond and drainage to the choriocapillaris around the burn sites.