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At least 397 records · Page 22Linked to original sources
PubMed1973

Results of cytogenetic studies of seeds after their extended orbital flight aboard the Salyut orbital scientific station.

Air-dry seeds of Lactuca sativa (lettuce) with a different level of spontaneous mitagenesis were used in these experiments. A part of the seeds was given pre-flight gamma radiation in doses of 1 and 10 krads. Comparison of the results for the in-flight experiments, laboratory and "transport" control showed an increase of cells with chromosome aberrations and an increase of radiobiological effect in irradiated seeds flown aboard the Salyut scientific station. A comparative analysis was made of the cytogenetic changes in seeds after their exposure to different periods of weightlessness during the Cosmos 368, Zond 8 and Salyut missions. The effect of weightlessness of different duration on the development of cytogenetic changes in irradiated and unirradiated seeds is discussed.

Chromosome Aberrations↗
PubMed1999

Direct orbital manometry in patients with thyroid-associated orbitopathy.

PURPOSE: To determine orbital tissue tension and orbital compartment compliance in patients with and without thyroid-associated orbitopathy (TAO). DESIGN: Prospective case series. PARTICIPANTS: Orbits of patients with TAO (18 orbits) and control patients without TAO (35 orbits) were studied. METHODS: An orbital manometer was designed to directly measure orbital tissue tension in patients undergoing ocular or orbital surgery. MAIN OUTCOME MEASURES: Tissue tension was recorded before, during, and for 5 minutes after a 5-ml retrobulbar injection of anesthetic. Orbital compliance was calculated as change in volume divided by change in tissue tension. RESULTS: Resting orbital tissue tension was 4.4 +/- 2.2 mmHg (mean +/- SD) in normal orbits and 9.7 +/- 4.8 mmHg in orbits of TAO patients (P = 0.0005) Following retrobulbar injection, orbital tissue tension rose to 12.0 +/- 3.6 mmHg (P = 0.0000000000000006 compared with baseline) in the control group and to 36.3 +/- 15.2 mmHg in the TAO group (P = 0.0000007 compared with baseline, and P = 0.000008 TAO group versus control group). Orbital compartment compliance was 0.80 +/- 0.50 ml/mmHg in the control group and 0.27 +/- 0.21 ml/mmHg in the TAO group (P = 0.00001). Resting orbital tissue tension in 8 TAO orbits with compressive optic neuropathy was 12.4 +/- 4.9 mmHg, and was 7.8 +/- 3.5 mmHg in 10 orbits of TAO patients without compressive optic neuropathy (P < 0.05). No adverse events occurred. CONCLUSIONS: Retrobulbar injection causes consistent measurable changes in orbital tissue tension. Orbital manometry safely demonstrated higher orbital tissue tension and lower orbital compartment compliance in the orbits of TAO patients versus those of normal subjects. Resting orbital tissue tension was higher in the orbits of TAO patients with compressive optic neuropathy than in those orbits without. Compressive optic neuropathy may partially result from an orbital compartment syndrome in some patients with TAO. Directly assessing orbital dynamics in vivo may prove useful as an adjunct in the clinical evaluation of patients with TAO and other orbital disorders.

Aged↗
PubMed2006

Evaluation of computer-based volume measurement and porous polyethylene channel implants in reconstruction of large orbital wall fractures.

PURPOSE: To describe the use of computer-based orbital volume measurement as a predictor of late enophthalmos, and to assess the effectiveness of the MedPor (Porex Surgical Products Group, Newnan, GA) porous polyethylene channel implant to restore orbital volume in repairing large orbital wall fractures. METHODS: Sixteen patients with unilateral large orbital fractures were included. Computed tomographic (CT) scans were used to obtain computer-based orbital volume measurement to predict the likelihood of late enophthalmos and to assess the change in orbital volume before and after surgery. The effectiveness of a channel implant was evaluated by the orbital volume and postoperative exophthalmetric measurement. RESULTS: The average time interval between injury and surgery was 17.4 +/- 10 days, and the mean follow-up was 9 months. The orbital volume of the injured orbit was significantly increased (mean, 4.22 +/- 2.61 cm2) compared with the unaffected orbit before surgery (t = 3.046, P = 0.005). There was not a significant difference in orbital volume between the two orbits after orbital reconstruction (t = 0.069, P = 0.945). The orbital volume change after reconstructive surgery was significantly positively correlated with the decrease of enophthalmos (r = 0.715, P = 0.001; enophthalmos [E] = 0.72; volume increment [V] = 0.06). To resolve 2 mm enophthalmos, more than 2.9 cm3 orbital volume augmentation is recommended for early reconstructive surgery. Postoperative CT scan showed most of the channel implants to be well positioned. CONCLUSIONS: Computer-based orbital volume measurement from a CT scan is useful in the posttraumatic evaluation of orbital fractures, and it can help predict the degree of late enophthalmos that can be expected. Orbital reconstruction with the MedPor channel implant (Porex Surgical Products Group), when indicated, is recommended, especially for large orbital wall fractures.

Adolescent↗
PubMed1999

The direct effect of intraorbital pressure on orbital growth in the anophthalmic piglet.

Tissue expanders placed within the orbit can have a positive effect on orbital and ipsilateral midfacial growth. To date, there is no precise method for controlling and monitoring expansion to induce normal growth in the developing facial skeleton. The present study was undertaken to determine the optimal physiologic pressure required to stimulate normal orbital growth and to determine whether above-normal growth could be achieved with higher intraorbital pressures. Using a neonatal swine model, an accurate method of monitoring intraorbital pressure, precisely controlling intraorbital expansion, and achieving normal orbital growth was explored. Sixteen male, 3-week-old Yorkshire piglets were randomly divided into three surgical groups. In each group, the left orbit was the experimental side, and the contralateral right orbit served as an untreated control. Group 1 (n = 6) underwent enucleation only. Group 2 (n = 5) underwent enucleation and orbital expansion at a near-normal physiologic pressure of 20 mmHg. Group 3 (n = 5) underwent enucleation and orbital expansion at a supernormal pressure of 60 mmHg. Spherical tissue expanders (10 cc) with a separate injection port were utilized as the orbital expanders. Pressure was monitored by an electronic manometer that was calibrated daily. Morphology of the orbits was documented by photography, the dimensions of the orbits were quantitated by three-dimensional mechanical digitization, and orbital volumes were calculated. In the unexpanded, anophthalmic control group, a significant reduction in radial growth after evisceration was seen. In group 2, the orbit stimulated with a consistent pressure of 20 mmHg, just above the physiologic normal pressure of 17 mmHg, showed an increase in radial dimension of 8 percent compared with the unoperated side. In the high-pressure group of 60 mmHg, an increase of 16 percent in the radius was observed over the 4-week period. This led to a corresponding increase in orbital volumes with increased pressure. Utilizing a paired t test, these differences in the radial and volumetric growth of the orbit were statistically significant (p < 0.005). The results obtained demonstrated a direct relationship between intraorbital pressure and the growth of the bony orbit in the radial dimension. On the basis of this study, we concluded that orbital expansion maintained at normal physiologic pressure can stimulate normal orbital growth in the neonatal facial skeleton. In addition, application of above-normal pressures for expansion can induce accelerated orbital growth.

Animals↗
PubMed2003

[Surgical correction of orbital and periorbital deformities using lamella and complex osteotomies].

OBJECTIVE: To investigate surgical correction of orbital and periorbital deformities in orbital and periorbital region. METHODS: In order to reconstruct orbital deformities such as orbital hypertelorism, orbital dystopia, radiated orbit, and secondary deformities of traumatic orbit, lamella osteotomies of either orbital rim and wall or complex osteotomies of both adjacent orbital rims and walls using bicoronal or galea aponeurotica incision were employed. The reconstructed complex was placed in new position with rigid fixation. Clinic evaluations were performed before and after operative osteotomies such as cephalometry (measurement of interorbital distance, IOD), exophthalmos (measurement with Hetel exophthalmometer), the angle (between orbital horizontal level and bilateral tragus linkage, A-OT), and the linear distance (between lateral canthus and tragus, LC-T), then the gap differences were analyzed before and after operation. RESULTS: Nearly normal orbital volumes, better contour of orbit and midface, improved eyelids and visions were achieved in total 44 cases. There were 5 cases of supraorbital osteotomy (intracranial routine), 8 cases of medial orbital osteotomy, 3 cases of inferior orbital osteotomy, and 28 cases of both lateral and inferior orbital osteotomy in these series. No complications were found after surgery. The orbital and midfacial appearances were improved significantly. CONCLUSIONS: Lamella and complex osteotomies of orbital rim and wall are proved to be safe and effective to correct most deformities of orbital and periorbital region and various kinds of orbital malposition.

Adolescent↗