Biomedical subjects
Publications and source records attributed to R A Hill.
Forty-two uncemented ICLH and Freeman Samuelson knee replacements that required bone grafting for tibial defects were studied before and after operation. The pattern of bone loss, the techniques of grafting, and the soft tissue releases required are described. Union of the graft was observed in 98% of cases, confirming the value of bone grafting in the reconstruction of the deformed, arthritic knee.
This study was undertaken to determine whether thermally-induced tissue necrosis was a factor in ab-interno contact-laser sclerostomy failure. A rabbit model was used to compare the continuous-wave Neodymium (Nd):YAG with the pulsed Erbium (Er):YAG laser with respect to such failure. Laser energy was focused into a fused-silica fiber optic (400 microns) for the Nd:YAG laser (12 W; 3 to 5 seconds), and into a single-crystal, uncladded sapphire fiber optic (250 microns) for the Er:YAG laser (7 to 8 mJ; 250 microseconds; 6 to 8 pulses). The Nd:YAG and Er:YAG lasers required from 21 to 35 J and from 42 to 64 mJ, respectively, to create the sclerostomies. Filtering blebs and intraocular pressure reduction lasted longer (log-rank test; P less than .03) and surgical complications were fewer in the Er:YAG group than in the Nd:YAG group. By creating sclerostomies with minimal thermal damage, the Er:YAG laser may offer significant clinical advantages over lasers producing larger thermal effects.
As part of a pilot study for glaucoma surgery, the use of 3 infrared solid state lasers with 4 fiber optic delivery systems to ablate human trabecular meshwork was investigated. Laser trabecular ablation (LTA) was attempted with the Erbium:YAG (2.94 microns), Erbium:YSGG (2.79 microns), and Holmium:YSGG (2.1 microns) lasers. Laser energy was delivered as a single pulse (250 microseconds) by tissue fiber optic contact with low hydroxyl-fused silica (200 and 500 microns), zirconium fluoride (250 microns), or sapphire (250 microns) fiber optics. Total energy required and thermal effects decreased as laser wavelength increased. LTA was best achieved at 2.94 microns (4 mJ total energy; energy densities = 8.2-12.7 J/cm2; pulse length 250 microseconds) with average thermal damage zones of 5.3-10.3 +/- 1.3-2.4 microns (means +/- SDs) to contiguous structures. This finding has potential applications in the surgical treatment of open-angle and congenital glaucoma and may minimize failure rates seen in other types of surgery on the trabecular meshwork where disrupted trabecular meshwork is not removed.
Seventy patients younger than 21 years of age underwent Molteno implantation for nonneovascular glaucoma. Fifty-three (76%) patients had failed angle and/or conventional filtering surgery. Final intraocular pressure less than 22 mmHg (but over 5 mmHg) was achieved in 40 (62%) of the 65 patients with at least 6-month follow-up (range, 6 to 59 months; mean +/- standard deviation, 22.7 +/- 14.1 months); however, only 22 (34%) were controlled after the initial Molteno implantation procedure, and 54 (83%) patients underwent further glaucoma and/or nonglaucoma surgical procedures. The visual acuities remained within one line of their preoperative levels or improved in 25 (68%) of the 37 patients on whom Snellen acuities were available. The most frequent complications included: tube-cornea touch (20%, transient in 3%), corneal edema (17%), retinal detachment (16%), tube block (10%), cataract (9%), chronic hypotony or phthisis (9%), pupillary or cyclitic membrane (9%), hyphema (7%), flat anterior chamber (6%), and large postoperative choroidal effusion (6%). Despite the high rates of subsequent surgical interventions and complications, Molteno implantation has been a useful approach for achieving intraocular pressure reduction in young patients with glucoma.
A randomized, prospective, double-masked study was undertaken to determine the risk of postcycloplegic intraocular pressure spikes in patients with open-angle glaucoma and to evaluate apraclonidine prophylaxis in minimizing these spikes. Patients were stratified as miotic treated or untreated and each group was randomized to receive either placebo (artificial tears) or apraclonidine in both eyes before instillation of tropicamide. In both the miotic treated and untreated groups that received placebo, there was a high incidence, (37% and 38%, respectively) of clinically significant (greater than or equal to 6 mmHg) intraocular pressure spikes after instillation of tropicamide. In both the miotic treated and untreated groups, there was a statistically significant difference in postcycloplegic intraocular pressure between the subgroup that received placebo and the group that received apraclonidine prophylaxis (P = 0.003 and P = 0.006, respectively). Additionally, four eyes that received placebo had a spike of over 10 mmHg (range, 12 to 27 mmHg), while only one eye had an increase of greater than 10 mmHg (12 mmHg) in the apraclonidine group. Thus, apraclonidine appears to be a useful agent for minimizing precipitous increases in intraocular pressure after cycloplegia in eyes of open-angle glaucoma patients prone to this complication of cycloplegia.
Four solid-state lasers with three fiberoptic delivery systems were used to perform laser sclerostomies in an acute-injury rabbit model and in fresh human globes. The lasers used were continuous-wave neodymium:yttrium aluminum garnet (YAG, 1.06 microns) and pulsed holmium:yttrium scandium galliam garnet (YSGG) (2.10 microns), erbium:YSGG (2.79 microns), and erbium:YAG (2.94 microns). Thermal damage to tissue and total laser energy required to produce sclerostomies decreased with increasing wavelength. In human tissue using a 600-microns fused silica fiberoptic, maximum thermal damage (greater than or equal to 100 microns) was noted at 1.06 microns with a total energy of 21 J at a power density of 2.5 kW/cm2. In addition, focal damage to the iris and ciliary body was noted at this wavelength. The least amount of thermal damage (15-20 microns) and lowest total energies needed were found at 2.94 microns. A 250-microseconds pulse length and pulse radiant exposures of 3.6 J/cm2 and 14.3 J/cm2 were used for the low hydroxyl-fused silica (500 microns) and zirconium fluoride (250 microns) fiberoptics, respectively. Although zirconium fluoride fibers have high through-put efficiencies that facilitate study of laser tissue interactions at 2.94 microns, problems encountered with fragility and solubility of the bare tip in aqueous media limit its usefulness. A high attenuation rate with the low hydroxyl-fused silica fiber limited its usable length to 35 cm at 2.94 microns. Tissue damage during sclerostomy formation was minimized at 2.94 microns, reaching a maximum at 1.06 microns. Minimizing tissue damage theoretically could decrease subconjunctival scarring and filtration failure.(ABSTRACT TRUNCATED AT 250 WORDS)
Significant morbidity and mortality can result if early detection and treatment of sphenoid sinusitis is not provided. A case is presented in which the diagnosis of sphenoid sinusitis was delayed because a routine computerized tomographic scan was normal. This case underscores the importance of specifically requesting views of the paranasal sinuses in suspected cases of sinusitis.
Closed locked tibial nailing is facilitated by accurate reduction of the fracture and careful positioning of the patient before surgery commences. The prerequisites for successful nailing are discussed.
We report the use of a symblepharon ring in the treatment of seven cases of flat anterior chamber (six cases of total iridocorneal touch, and one of corneallens touch) secondary to overfiltration or to bleb leak. In all cases, the anterior chamber reformed within 24 hours after the symblepharon ring was used. Advantages of using the ring are: (a) it permits testing of visual acuity, tonometry, and intraocular examination without removing it; (b) it does not require suturing to the conjunctiva; (c) it does not disturb the corneal epithelium; (d) it may be available at institutions lacking other shells; and (e) it is cost-effective.
Mast cell heterogeneity has been described on the basis of differential staining reactions, light microscopic morphology, anatomic location, degranulation after polyamines, biochemical contents, growth requirements, and reactions to lymphokines. We have demonstrated typical "connective-tissue mast cells" by using anatomic criteria, histological staining reactions, electron microscopy, and reaction to compound 48/80 in the guinea pig conjunctiva, eyelid skin, and ileum. A second, much larger population of cells in the ileal mucosa and the conjunctiva, and rarely in the eyelid skin stained reddish-blue with acid toluidine blue in tissue fixed in ethanol-acetate-lead subacetate (BLA) and with alkaline Giemsa in formaldehyde-fixed tissue, did not stain with ethanolic or acid toluidine blue in formaldehyde-fixed tissue or with alkaline Giemsa in BLA-fixed tissue, and did not degranulate after 48/80 treatment. These are features of the rat intestinal "mucosal mast cells"; however, ultrastructural and light microscopic studies with the orcein Giemsa stain demonstrated these cells in the guinea pig to be eosinophils. Tissue culture, biochemical, and immunological studies indicate the existence of a second type of mast cell (bone-marrow-derived mast cell), ultrastructurally almost indistinguishable from the connective tissue mast cell. Our studies demonstrate only one mast cell type in the guinea pig and support the contention that other forms of mast cells are immature forms or variants of the connective-tissue mast cell.
The prevalence of wheezing, 'asthma', treatment for 'asthma', and school absence as a result of wheezing in Nottingham was calculated from a questionnaire survey of parents of 4750 children in a random sample of primary schools. A response was achieved for 3805 (80%) children of whom 438 (11.5%) had had episodes of wheezing in the last year and 224 (5.9%) had been diagnosed as having asthma. Asthma treatment had been prescribed for 251 (6.6%) of all children, two thirds of all the children receiving drugs. Two hundred and sixty five (7%) children had lost time from school because of wheezing (median loss of seven days). Of the 64 children losing more than 10 days, 45 (70%) were not taking any drugs, or taking only beta agonists. The prevalence of wheezing found by this survey was comparable with that in similarly designed surveys, though the proportion of children diagnosed as having asthma was higher. Though doctors may now diagnose asthma more readily wheezing still remains an important cause of school absence and still seems to be undertreated.
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A method of superimposing a film on a xeroradiographic (XR) cassette for simultaneous intraoral exposure is evaluated for use as an imaging technique in clinical studies comparing Ektaspeed film and XR images. Sandwich images were indistinguishable from those produced by conventional technique. Pilot studies were conducted with 104 patients who had symptomatic dental problems. No significant differences were found in diagnostic usefulness or image quality between XR and film radiographs when sign test analysis was used. The sandwich technique yielded film and XR images with duplicate image geometry while reducing patient exposures to one half of that used in conventional image comparison protocols.
The study was designed to ascertain the relationship between visual loss in the central 30 degrees of vision and the density of the relative afferent pupillary defect (APD). The APD of 26 patients was quantified using a neutral log density filter. The mean threshold light sensitivity on Humphrey automated perimetry (Program 30-1) of one eye was substracted from the fellow eye total to yield the interocular visual field difference (VFD). A direct correlation was noted such that the log density of the APD increased linearly with an increase in VFD (r = 0.69, P = 0.0001). In the absence of ptosis or ocular media opacification, a VFD greater than 8.7 that is not associated with an APD is suggestive of functional visual loss. Four patients had an APD despite normal static automated perimetry, indicating that an APD may be one of the earliest signs of retinal ganglion cell or axonal dysfunction.
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An isolate of Aspergillus parasiticus CP461 (SRRC 2043) produced no detectable aflatoxins, but accumulated O-methylsterigmatocystin (OMST). When sterigmatocystin (ST) was fed to this isolate in a low-sugar medium, there was an increase in the accumulation of OMST, without aflatoxin synthesis. When radiolabeled [14C]OMST was fed to resting mycelia of a non-aflatoxin-, non-ST-, and non-OMST-producing mutant of A. parasiticus AVN-1 (SRRC 163), 14C-labeled aflatoxins B1 and G1 were produced; 10 nmol of OMST produced 7.8 nmol of B1 and 1.0 nmol of G1, while 10 nmol of ST produced 6.4 nmol of B1 and 0.6 nmol of G1. A time course study of aflatoxin synthesis in ST feeding experiments with AVN-1 revealed that OMST is synthesized by the mold during the onset of aflatoxin synthesis. The total amount of aflatoxins recovered from OMST feeding experiments was higher than from experiments in which ST was fed to the resting mycelia. These results suggest that OMST is a true metabolite in the aflatoxin biosynthetic pathway between sterigmatocystin and aflatoxins B1 and G1 and is not a shunt metabolite, as thought previously.
A questionnaire on asthma in schools was circulated to 291 Nottingham schools. The response rate was 91%. Three areas of concern were identified: are schools aware of all their asthmatic pupils; should children have more access to their medications in school; and do teachers need more guidance in supervising illnesses.