To assess potential effects of hyperbaric oxygen (HBOT) on artificial bone grafts, β - Tricalcium phosphate (β-TCP) and calcium phosphate coated bovine bone (CPCBB) substitutes were applied to standard bone defects in rat tibiae. The control defects were left empty. Half of the animals received 60 minutes of 2.4 atmosphere absolute (ATA) of HBOT. Rats were sacrificed at one, two and four weeks. Bone healing was assessed histologically and histomorphometrically using light microscopy. The periosteum over the bone defects was examined ultrastructurally. Cardiac blood was collected to determine the serum osteocalcin levels. The HBOT increased new bone formation in the unfilled controls and β-TCP groups and significantly decreased cartilage matrix and fibrous tissue formations in all groups. Active osteoblasts and highly organized collagen fibrils were prominent in the periosteum of β-TCP and control groups. Serum osteocalcin levels also increased with HBOT. The healing of defects filled with CPCBB was similar to the controls and it did not respond to HBOT. These findings suggested that the HBOT had beneficial effects on the healing of unfilled bone defects and those filled with β-TCP bone substitute but not with CPCBB, indicating a material-specific influence pattern of HBOT.

Quantitative descriptions of the occipital sinus are lacking in the extant medical literature. Posterior fossa duras with the superior sagittal sinus, the inferior and superior petrosal sinuses were dissected and taken out from fresh human cadavers by cutting at the superior sagittal sinus, the marginal sinuses and the petrosal sinuses bilaterally. The length of the occipital sinuses was measured using calipers. A 0.5-cm section of the occipital sinus was cut out at its midpoint and prepared for measurements of the perimeter and diameter using a stereology workstation. The sinuses were also examined qualitatively using a surgical microscope. There was no occipital sinus in 6.6% of total 30 cases. Multiple occipital sinuses were seen in 10%. In one specimen, the sinus seemed incomplete, failing to reach the marginal sinuses. Some specimens gave the impression that more than one occipital sinus was present, nevertheless, careful dissection showed connections. The breadth of the sinus steadily narrowed downward in direction of foramen magnum. The inner wall with many fibrous bridges was tight, except the lateral parts that were easily separated into two dural sheets. The length of the sinus varied from 10 to 37 mm. The inner diameter (feret maximum) varied from 0.33 to 7.06 mm at midpoint. The breadth of the multiple sinuses did not exceed the mean of our series except in one case. The occipital sinus, which is generally ellipsoid in shape, functions in the majority of cases as a thin, single midline sinus. It may have less resistant recesses laterally.

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