The supraodontoid space or "apical cave" at the craniocervical junction: a microdissection study.

The extradural supraodontoid space lies anteriorly at the craniocervical junction (CCJ) between the alar ligaments and foramen magnum. It occupies the space between the tectorial and atlanto-occipital membranes. A variety of benign and traumatic lesions may result in neurological compression here with harmful effects. Decompression by the transoral surgical approach often provides relief from these effects. Knowledge of the detailed microanatomy of this space is fragmentary. The purpose of this study was to identify the boundaries and contents of this space by microdissection. Twenty-three en bloc preserved adult cadaveric specimens of the CCJ were dissected to identify the boundaries and contents of the supraodontoid space. The posterior bony elements of the CCJ were removed to enable microdissection (Zeiss DXE Microscope 4-40x) from the tectorial membrane (TM) forwards. The cave-like space faced posteriorly. It had a roof which extended into a wall (anterior atlanto-occipital membrane), a floor (superior surface of the alar ligament), and a mouth covered by the TM. The apical ligament and a thin lining membranous fatty layer divided the cave into a pair of symmetrical halves. The contents, from dorsal to ventral, lay deep to a thin subtectorial membrane. These were the superior fasciculus of the cruciate ligament, a fat-ensheathed knot of plexiform veins (which communicated with the surrounding CCJ vertebral venous plexuses), an arterial arcade between the veins, a pair of fat pads, and branches of the sinuvertebral nerves of the CCJ (lying on the floor). No synovial membrane was found. Knowledge of the anatomy of the apical cave may be of some assistance in transoral (extra- and transdural) surgical approaches to the anterior CCJ region.

Affinity chromatography using biocompatible and reusable biotinylated membranes.

A novel, reusable biotinylated affinity chromatography strategy for the bio-specific binding of bioactive avidin tagged enzymes or polypeptides is reported. Using an avidin coupled peroxidase fusion protein as a test system; non-specific protein shielding and matrix regeneration were also shown. The amphiphilic surfactant Pluronic F108 was used as an affinity linker, by non-covalent binding to membrane chromatographic matrices while the terminal hydroxyl groups of Pluronic were covalently coupled to the biological ligand biotin. Planar nonporous membranes of varying surface chemistry were synthesised to test the matrix dependent affinity binding of biotinylated Pluronic and their respective ability to resist non-specific protein adsorption. Membrane regeneration using sodium dodecyl sulphate (SDS) was capable of displacing both adsorbed proteins and Pluronic. SDS micelles (34 mM) were effective in desorbing membrane bound protein while 5mM SDS removed up to 85% of the bound ligand after 20 h incubation at 20 degrees C. In this study, polyvinylidene membranes had the highest ligand binding capacity of 0.22 mg cm(-2) and specific, competitive affinity binding of avidin-peroxidase was shown in the presence of up to 0.2 mg ml(-1) 'contaminant' proteins. The resultant biocompatible affinity chromatographic system was regenerated and reused with no significant change in performance for up to five cycles.

A robust approach to studying the adsorption of Pluronic F108 on nonporous membranes.

A method for poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) desorption from synthetic nonporous polymeric membranes, using hexane:isopropanol treatment and subsequent colorimetric quantification, is described. The polymers polysulfone, poly(vinyldiene fluoride), and poly(ether imide) were used to fabricate solid adsorption matrices. The desorbed Pluronic F108 forms a color complex with ammonium ferrothiocyanate (NH4FeSCN) and is based on partitioning of a chromophore present in NH4FeSCN from an aqueous phase to a chloroform phase in the presence of Pluronic. The protocols for Pluronic desorption and detection are simple, sensitive, inexpensive, rapid, and reproducible over a wide range of Pluronic coating concentrations and membrane surface chemistries. A linear response over the concentration range from 3 to 130 microg ml(-1) is obtained. The adsorption isotherms for flat sheet membranes are also described and the Langmuir equation provides the best fit for the adsorption data obtained within the concentration range studied. The absence of any significant interference from certain proteins, vitamins, carbohydrates, plasma, and halogenated derivatives makes the assay equally suitable for the estimation of Pluronic F108 in the attendant Pluronic conjugates or in biomedical applications. Using nonporous hollow fine fibers and capillary membranes as model curved substrates we were also able to correlate an increase in the radius of curvature with a corresponding increase in the surface interfacial adsorption of Pluronic F108.

Fractures of the odontoid process.

We treated 183 patients with fractures of the odontoid process (109 type II, 74 type III) non-operatively. Union was achieved in 59 (54%) with type-II fractures. All type-III fractures united, but in 16 patients union was delayed. There was no correlation between union and the clinical or radiological outcome of the fractures. Selective vertebral angiography, carried out in 18 patients ten with acute fractures and eight with nonunion, showed that the blood supply to the odontoid process was not disrupted. Studies on ten adult axis vertebrae at post-mortem showed that the difference in the surface area between type-II and type-III fractures was statistically significant. Our findings show that an age of more than 40 years, anterior displacement of more than 4 mm, posterior displacement and late presentation contribute towards nonunion of type-II fractures.

Haemangiopericytoma of the floor of the mouth. A case report.

Haemangiopericytoma of the floor of the mouth with metastases to the lumbar spine in a 23-year-old black woman is described. She represents the 36th patient with oral cavity haemangiopericytoma and the 4th with a floor of mouth lesion. The aggressive behaviour of haemangiopericytoma and its resistance to all forms of recommended treatment was shown in this patient.

Enhancing drug incorporation into tetracycline-loaded chitosan microspheres for periodontal therapy.

PURPOSE: To identify optimal formulation parameters for enhancing the incorporation of tetracycline hydrochloride into chitosan microspheres for periodontal therapy. METHODS: Tetracycline-loaded chitosan microspheres were prepared by ionotropic gelation. Various formulation parameters (salt form of drug, aqueous phase pH, anion structure, inorganic salts and electrolytes, preparation method) were investigated for their influence on drug incorporation efficiency. Microspheres were assessed in terms of drug entrapment and content, microsphere recovery, particle size and morphology. RESULTS: Although drug incorporation efficiency was increased marginally, the use of a dihydrate form of the drug was not considered feasible due to the lowered microsphere recovery and higher costs. A decrease in the aqueous pH from 9 to 6 enhanced drug incorporation efficiency without an adverse effect on microsphere morphology. The use of inorganic salts/electrolytes and other approaches of microsphere preparation did not significantly enhance drug incorporation efficiency and these approaches also adversely affected microsphere morphology. The ionotropic preparation method in terms of the drug loading technique significantly affected drug incorporation efficiencies. CONCLUSIONS: This study has shown that formulation variables can be exploited in order to enhance the incorporation of a water soluble drug into chitosan microspheres using the ionotropic gelation technique. Based on a comparison of all results obtained with the different approaches, the modification of the aqueous phase to pH 6 was identified as the most feasible approach.

Post-traumatic ligamentous instability of the atlantoaxial joint: a comparison between the Gallie and Brooks fusions.

We reviewed 37 patients following a posterior spinal fusion for traumatic ligamentous instability of the atlanto-axial joint. All patients were neurologically intact and the atlanto-dental interval ranged from 5 to 9 mm. A Gallie fusion was performed in 19 patients, a Brooks fusion in 16 patients and an occipitocervical fusion in two patients. A SOMI brace was used postoperatively for 12 weeks. Bony fusion was obtained in 32 patients. Displacement occurred in 11 patients, five of whom developed non-union.

A scalable membrane gradostat reactor for enzyme production using Phanerochaete chrysosporium.

This is the first demonstration of process scale-up of a membrane gradostat reactor for continuous enzyme production using Phanerochaete chrysosporium ME446. The fungus was immobilised by reverse filtration on to externally unskinned, ultrafiltration capillary membranes and then nutrient gradients were induced across the biofilm. A 10-fold scale-up from a single capillary bioreactor to a 2.4 l multi-capillary unit resulted in a 7-fold increase in enzyme productivity with a peak at 209 U l(-1) d(-1). Subsequent scale effects on the spore distribution, continuous manganese peroxidase production profile and biofilm development are discussed.