Benign intracranial hypertension and recombinant growth hormone therapy in Australia and New Zealand

Benign intracranial hypertension (BIH) is reported in three children from Australia and one from New Zealand, who were being treated with recombinant human growth hormone (rhGH). Three males and one female, aged between 10.5 and 14.2 y, developed intracranial hypertension within 2 weeks to 3 months of starting treatment. A national database, OZGROW, has been prospectively collecting data on all 3332 children treated with rhGH in Australia and New Zealand from January 1986 to 1996. The incidence of BIH in children treated with growth hormone (GH) is small, 1.2 per 1000 cases overall, but appears to be greater with biochemical GHD (<10IUml ^-1), i.e. 6.5/1000 (3 in 465 cases), relative risk 18.4, 95% confidence interval 1.9-176.1, than in all other children on the database. The incidence in patients with Turner's syndrome was 2.3/1000 (1 in 428 cases). No cases in patients with partial GHD (10–20 IUml ^-1) or chronic renal failure were identified. Possible causative mechanisms are discussed. The authors'practice is now to start GH replacement at less than the usual recommended dose of 14IUm-² week^-1 in those children considered to be at high risk of developing BIH. Ophthalmological evaluation is recommended for children before and during the first few months following commencement of rhGH therapy and is mandatory in the event of peripheral or facial oedema, persistent headaches, vomiting or visual symptoms. The absence of papilledema does not exclude the diagnosis.     

Role of matrix metalloproteinases in failure to re-epithelialize after corneal injury.

Delayed re-epithelialization of the cornea after injury usually precedes stromal ulceration. Previous findings using a rat thermal injury model suggested that re-epithelialization is impeded by products of resident corneal cells, which destroy adhesive structures at the basement membrane zone. In this study, we provide additional evidence for this concept. Failure to re-epithelialize was found to correlate with an increase in the amounts of gelatinolytic matrix metalloproteinases present in the rat cornea. One of these gelatinases, gelatinase B, is synthesized by the resident corneal cells, and inhibitions of its synthesis correlated with inhibition of basement membrane dissolution. The matrix metalloproteinases collagenase and stromelysin are also synthesized by resident corneal cells in thermally injured corneas of rabbits, but the timing of bulk enzyme synthesis correlated more closely with deposition of repair tissue in the stroma than with failure to re-epithelialize. Nevertheless, in human corneas with repair defects, gelatinase B and collagenase are synthesized by cells in the basal layer of the epithelium directly adjacent to the basement membrane, suggesting that both could participate in dissolution of this structure. Importantly, treatment of thermally injured corneas with a synthetic inhibitor of matrix metalloproteinases significantly improved basement membrane integrity. These data support the concept that over-expression of matrix metalloproteinases by resident corneal cells impedes re-epithelialization after some types of corneal injury.     

Semiautomated determination of minimum bactericidal concentrations of antibiotics

Using a newly devised 50-channel photometer which records the opacity of growing bacterial cultures, it was shown that the time taken by cultures diluted 1/1000 in fresh broth to reach 50% of the opacity of a fully grown culture was inversely related to the concentration of organisms in the original culture. This relation was used to determine the numbers of survivors after exposure to benzylpenicillin and gentamicin alone and in combination. The procedure is commended as a labour-saving and potentially rapid method of obtaining comprehensive information on the bactericidal action and interaction of antibiotics.     

The effect of gamma interferon on IL-1 secretion of in vitro differentiated human macrophages

After being cultured overnight, human monocytes lose their ability to secrete interleukin-1 (IL-1) when stimulated by lipopolysaccharide (LPS). However, when these monocytes were cultured for up to 9 days with various concentrations of interferon-gamma (IFN-gamma), these cells were found to retain their ability to secrete appreciable amounts of IL-1 on LPS stimulation. However, the effect was observed only if the monocytes were exposed to the IFN before LPS stimulation and simultaneous addition of IFN and LPS to macrophages was ineffective. This effect of IFN-gamma was related to the concentration of IFN added to the cultures and was completely neutralized by a monoclonal antibody to IFN-gamma. In addition to inducing IL-1 secretion, IFN-gamma also appeared to increase the overall production of IL-1, since reinduction of IL-1 secretion was not associated with a decrease in intracellular IL-1 content. When these macrophages were initially cultured with IFN-gamma, washed, and further cultured with IFN free medium, these macrophages were found to progressively lose their capacity to secrete IL-1 in response to LPS. Conversely, when monocytes were initially cultured in medium free of IFN, washed, and then further cultured in new medium, but now containing IFN-gamma, these macrophages were found to regain their capacity to secrete IL-1. However, the amount of reinduced IL-1 secretion decreased as the length of the initial culture period without IFN increased, with less than optimal IL-1 secretion occurring if monocytes were allowed to mature for 6 days before IFN-gamma pretreatment. In summary, these studies suggest that IFN-gamma may be important in enhancing IL-1 production and secretion by maturing macrophages and tissue macrophages and consequently may play a role in regulating the accessory cell activity of these cells for a variety of immune responses in vivo.     

Initial evaluation of a continuous speech recognition program for radiology

The aims of this work were to measure the accuracy of one continuous speech recognition product and dependence on the speaker's gender and status as a native or nonnative English speaker, and evaluate the product's potential for routine use in transcribing radiology reports. IBM MedSpeak/Radiology software, version 1.1 was evaluated by 6 speakers. Two were nonnative English speakers, and 3 were men. Each speaker dictated a set of 12 reports. The reports included neurologic and body imaging examinations performed with 6 different modalities. The dictated and original report texts were compared, and error rates for overall, significant, and subtle significant errors were computed. Error rate dependence on modality, native English speaker status, and gender were evaluated by performing ttests. The overall error rate was 10.3 +/- 3.3%. No difference in accuracy between men and women was found; however, significant differences were seen for overall and significant errors when comparing native and nonnative English speakers (P = .009 and P = .008, respectively). The speech recognition software is approximately 90% accurate, and while practical implementation issues (rather than accuracy) currently limit routine use of this product throughout a radiology practice, application in niche areas such as the emergency room currently is being pursued. This methodology provides a convenient way to compare the initial accuracy of different speech recognition products, and changes in accuracy over time, in a detailed and sensitive manner.     

Three-dimensional surface reconstructions using a general purpose image processing system

A general purpose two-dimensional (2-D) image processing software system was used to produce high quality three-dimensional (3-D) surface reconstructions from serial sections such as CT scan slices. Depth-encoded 3-D surface images, gradient-shaded 3-D surface images, and weighted sums of these two images were computed. Images that simulate transmission radiographs ("volumetric" views) were created from the same slice data. Hidden surfaces were displayed by reconstructing in 3-D only subvolumes of the original data set. The 2-D image processing functions used were limited to: planar subimage selection and merge, arithmetic and boolean operations, piecewise linear gray scale transform, convolution (1-D), and format conversion (byte-integer-float). Using these methods any user with a general purpose 2-D image processing system can analyze and view multi-slice data as 3-D volume and surface projections.