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Biomedical subjects

B V Worgul

Publications and source records attributed to B V Worgul.

At least 55 records · Page 3Linked to original sources
PubMed1984

Accelerated heavy particles and the lens. I. Cataractogenic potential.

The effect of varying doses of accelerated (570 MeV/ amu ) argon ions on the rat lens is described with detailed observations on the sequence of development of the cataracts, the time-dose relationship, and the analysis of their cataractogenic potential. The relative biological effectiveness (RBE) of the heavy particles for cataract production, compared to low linear energy transfer (LET) radiation (X rays), has been established. These data indicate that, as with neutrons, the RBE increases with decreasing dose and that at a dose of 0.05 Gy an RBE of about 40 was observed.

Animals↗
PubMed1983

Scanning electron microscopic analysis of radiation cataracts in rat lenses. I. X-radiation cataractogenesis as a function of dose.

Cataracts produced in 4-week-old rats following exposure of the eye to various doses of 185 kVp X-rays, were analyzed 45 days after irradiation by scanning electron microscopy (SEM), as well as by conventional light microscopy (LM). The severity and extent of the ultrastructural damage seen at the LM and SEM levels varied as an increasing function of dose and correlated well with the clinical changes which were scored by slitlamp biomicroscopy prior to preparation. In the early-stage low-dose cataracts, damage was generally limited to the equatorial and posterior subcapsular regions. The late-stage high-dose cataracts were associated with clusters of 4 to 10 microns globules at the poles subcapsularly, massive disruption of the equatorial region and the formation of a granular matrix which extended to the posterior pole. Ultrastructural changes were also noted in the superficial cortical region, while the lenticular nucleus and the residium of the cortex remained unchanged.

Animals↗
PubMed1982

The lens epithelium and radiation cataract. IV. Ultrastructural studies of interphase death in the meridional rows.

The effect of radiation upon the differentiating meridional row cells of the rat lens epithelium was studied by electron microscopy. X-irradiation of rat lenses was shown to disrupt the nuclear and, in some instances, the cytoplasmic organization of these cells. Indications of damage, 4.5 h post-irradiation, are a disruption in the shape of the nucleus and its membranes. This is typified by a bulging or blebbing of the nucleus. At 12 h the affected nuclei deteriorate with obvious membrane breakdown. The nucleoplasm at this time may appear highly condensed and shrunken. Disruption of the plasma membrane is also evident. Based upon previous findings it is likely that the nuclear changes are independent of the processes involved in normal fiber denucleation.

Animals↗
PubMed1982

Radiation cataractogenesis in the amphibian lens.

This report describes a reproducible and characteristic sequelae for radiation cataractogenesis in the amphibian. The development of lens opacification was investigated as a function of dose and time after X-irradiation of the eye of postmetamorphic bullfrogs. It was found that the development of radiation cataracts in frogs is both age and dose dependent. It was also determined that, far from being radiation resistant, frog lenses are sensitive to doses that are moderately cataractogenic for mammals.

Age Factors↗
PubMed1981

Cataractogenesis in the X-irradiated rabbit eye.

Studies were conducted on the development of cataract in the eyes of young (5-6 week old) New Zealand White rabbits exposed to 20 Gy of X-rays (1 Gy = 100 rads). The findings indicated that the opacities appear initially during the first week post-irradiation and follow a progression typical of cataract development in older rabbits and other species. However, advanced cataractous changes, as indicated by lens intumescence, occur concomitantly with complete opacification. They develop rapidly within a two day period between 2.5 to 3 months post-irradiation.

Animals↗
PubMed1980

Hypophysectomy exerts a radioprotective effect on frog lens.

Exposure to X-rays usually causes cataracts in frogs. These cataracts are always preceded by misalignment of the structures called meridional rows (MR). When cell division is completely halted by hypophysectomy, however, irradiation no longer disturbs the orientation of the MR. Since the MR are the structures formed as lens epithelial cells differentiate into lens fibres it is reasonable to propose that radiocataractogenesis depends upon a mitosis-driven formation of pathological fibres from epithelial cells that have been rendered abnormal by exposure to X-rays.

Animals↗
PubMed1980

Endotoxin-induced uveitis in the rat.

Experimental studies of ocular inflammation induced by endotoxin have been performed almost exclusively in rabbits. Although the rat has been considered refractory to both the systemic and local effects of endotoxin, the present study has shown that intravitreal injection of endotoxin evoked a characteristic acute inflammatory response which was reproducible and dose-dependent. In addition, a consensual ocular response in the control eye occurred which was less severe but also dose-dependent. Preliminary investigations support the view that consensual responses of this nature may be mediated by a nervous reflex are mechanism. Sequential histological analysis revealed a marked polymorphonuclear cell infiltration of most ocular tissues in the early stages, while mononuclear cells predominated after 3 days. Widespread intravascular microthrombi were also observed, particularly in the ciliary vessels. Recovery, however, was usually complete by 7 days.

Animals↗
PubMed1979

The effect of endotoxin-induced intraocular inflammation on the rat lens epithelium.

Intraocular inflammation induced by an intravitreal injection of Shigella endotoxin into the rat eye produces early changes in the number of dividing cells of the lens epithelium and affects the organization of the meridional rows. A depression in mitotic activity in the germinative zone is observed during the first 24 hr after injection. At 48 hr, despite the continued mitotic inhibition in the germinative zone, an increase in cell division occurs in the central zone. By 72 hr, the germinative zone mitosis reappears and exceeds control values, whereas the central zone mitotic activity returns to normal. At that time mitotic figures are found in the transitional zone. Disorganization of the meridional rows is seen as early as 12 hr after injection (the first time period observed) and reaches a peak by 48 hr. During the next 5 days, however, the severity of the disorganization diminishes. By the seventh day the rows appear, for the most part, fully recovered, and the mitotic activity reaches normal or near-normal levels in all regions. The details of these observations and their possible relationship to inflammatory cataracta complicata are discussed.

Animals↗
PubMed1976

Lens epithelium and radiation cataract. I. Preliminary studies.

The migration of epithelial cells during fibergenesis in the lenses of young rats was determined by tritiated thymidine autoradiography. Cells initially labeled in the germinative zone appeared in the lens bow within seven days. Irradiation with either 600 or 2,400 rads of x-rays did not greatly alter the migration rate, but it did interfere with normal differentiation and proper fiber deposition, as manifested by a displacement posteriorly of the lens bow nuclei and an accumulation of abnormal nucleated fibers in the posterior part of the cortex. The presence of labeled cells in those regions prior to the onset of opacification is consistent with the possibility of direct epithelial cell involvement in radiation cataractogenesis.

Animals↗
PubMed1975

Seasonal variations in mitosis in the frog: a field study.

Field studies have shown that there is a seasonal variation in mitosis of lens and corneal epithelium (high in May and June, low during the rest of the year). This phenomenon can be reproduced in the laboratory by temperature manipulation. The response in the lens depends on the presence of the pituitary gland while the corneal one seems to be independent of it.

Animals↗