Calculations of flow resistance in the juxtacanalicular meshwork

The structure of the juxtacanalicular meshwork (JCM) was analyzed morphometrically, and the resulting data were used to calculate the resistance to flow through this tissue. Two models of the JCM were presented and compared. In the first (Model A), aqueous humor was assumed to flow via open channels within a solid framework, while, in the second (Model B), these open spaces were assumed to be filled with extracellular matrix gel. An expression giving the resistance of such a gel as a function of gel concentration was presented and tested on corneal and scleral stroma. Morphometry of normal and glaucomatous human eyes showed that Model A underpredicted the resistance of the JCM by factors of 10-100, suggesting that a GAG or proteoglycan gel may control the flow resistance of this tissue. This was supported by Model B, which showed that measured bulk concentrations of GAGs were consistent with gel concentrations needed to account for the estimated resistance of the JCM in vivo. Some limitations and implications of Model B were discussed.     

Inactivity of methylene chloride in the mouse bone marrow micronucleus assay

Methylene chloride (MC) has been evaluated for its ability toinduce micronucleated polychromatic erythrocytes (MPEs) in thebone marrow of treated mice. Groups of five male and five femaleC57BL/6J/Alpk mice were exposed, by gavage, to doses of 4000,2500 and 1250 mg/kg MC in corn oil, the highest dose-level beingselected to be the maximum tolerated dose. Bone marrow sampleswere taken 24, 36, 48 and 72 h after dosing. No significantincreases in the incidence of MPEs over controls were observedfor any of the test groups, and it is concluded that MC is notclastogenic in this assay.     

Orthopedic aspects of competitive swimming

Orthopedic problems related to competitive swimming are rarely disabling, but can be problematic in preventing training and competition. Most problems are related to the shoulder and knee. Treatment is primarily nonsurgical and directed at relieving symptoms and allowing the athlete to continue with swimming practice. Treatment aids such as ice packing, anti-inflammatory medications, muscle stimulation and electrogalvanic stimulation, strengthening exercises, and static stretching are encouraged; upper arm bands and patellar-stabilizing supports can be adapted to training routines.     

Epidemiologic study by DNA typing of a Candida albicans outbreak in heroin addicts.

The epidemiology of an outbreak of Candida endophthalmitis in heroin addicts was studied by DNA typing. Although one biotype was prevalent, the 13 isolates of Candida albicans from seven of the patients were placed into six separate groups by DNA type. Thus, the outbreak of candidiasis was not, as had been concluded from biotyping, due to a C. albicans strain of common origin.     

Benign giant cell tumour with metastases to bone and lung. One case studied over 20 years

We report a case of benign giant cell tumour which over a 20-year period has given rise to pulmonary and bony metastases. The indolent nature of these metastases is remarkable, with considerable implications for the long-term management of such cases.     

Chorioretinal neovascular membranes complicating contusional eye injuries with indirect choroidal ruptures.

Chorioretinal neovascular membranes are a recognised but rare cause of late visual loss in eyes suffering contusional injuries. A series of eight cases is presented all with indirect choroidal ruptures involving the perifoveal region. Two main patterns of 'at risk' rupture were noted: a temporally situated rupture passing almost directly through the fovea, and a rupture which curves inferior or superior to the optic disc stopping just short of the fovea. In six of eight cases there was only a partial thickness rupture of the choroid. These neovascular membranes may present at any time after the original injury, either early (within six months of the injury), which could be related to persistence of the normal reparative neovascular response, or late (at least one year after the injury), which are more likely to have resulted from a secondary breakdown of the outer blood-retina barrier.     

Subcortical white matter lesions in osmotic demyelination syndrome.

We describe a case of histologically proved osmotic demyelination syndrome. In addition to abnormal T2 signal within the pons and thalami, MR showed linear enhancing lesions at the cortical medullary junction.