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Biomedical subjects

N Brown

Publications and source records attributed to N Brown.

At least 235 records · Page 13Linked to original sources
PubMed1981

Ceforanide kinetics.

Pharmacologic studies of the semisynthetic cephalosporin ceforanide were conducted in 29 cancer patients. Intravenous doses of 500 mg over 30 min every 6 hr to 10 patients induced mean peak serum concentrations between 44.7 and 51.5 micrograms/ml, while in 10 patients receiving 1 gm over 30 min every 12 hr mean peak serum concentrations varied from 73.4 to 91.8 micrograms/ml. Twelve hours after 1 gm of drug, mean serum concentrations varied between 5.6 and 6.5 micrograms/ml. After a 500-mg loading dose, continuous infusion of 500 mg every 4 hr, 10 patients maintained serum concentrations above 34.2 micrograms/ml for 7 or 8 days. Most of the drug was excreted in the urine in the initial 6 hr after administration and mean urinary concentration of 1,315 micrograms/ml were obtained during this time. Serum half-life ranged between 2.2 and 2.9 hr on all schedules and therefore wa longer than that of other cephalosporins. No serious toxicity was noted. The relatively broad spectrum of activity in addition to the long half-life suggests clinical utility for this drug.

Adolescent↗
PubMed1977

Cataract in childhood: photograph methods in assessment.

The slit-lamp examination of the child's lens with cataract can yield useful prognostic signs, especially when this is supplemented by slit-image photography and measurement. A normal lens size for the subject's age is a good prognostic sign and is usually associated with a static cataract or with very slow deterioration in a developmental cataract. A small lens and absence of the anterior subcapsular clear zone are each associated with progressive cataract. Nuclear lamellar cataracts are shown to become smaller in diameter with time, which favours medical treatment with mydriasis.

Adolescent↗
PubMed1976

Renal papillary necrosis in sickle cell hemoglobinopathies.

Approximately 65 per cent of patients with clinical manifestations of S-hemoglobinopathies show urographically demonstrable changes of renal papillary necrosis, regardless of the presence of urinary symptoms. With a more precise excretory urographic technique these changes can be diagnosed with greater accuracy without the need for sophisticated equipment. Excretory urography should be performed routinely in the evaluation of all patients with manifestations of S-hemoglobinopathy in order to diagnose papillary necrosis before the onset of urological symptoms.

Adolescent↗
PubMed1976

Recurrent erosion of the cornea.

Altogether, 80 patients aged between 24 and 73 years with recurrent erosion of the cornea have been studied and compared with a control group of 200. The patients' erosions were divisible into macroform and microform types. The macroform occurred in 10%, the microform in 56%, and both types in the same patients in 31%. The macroform was more commonly related to trauma than the microform. However, many (40%) were spontaneous in origin. The most common cause of the initial trauma was a finger nail. The recurrences occurred at around the time of waking, either just before or just after. Difficulty in opening the eye occurred in 10%. There was little evidence of precipitating factors, but eye rubbing was admitted by 10% and barbiturates were implicated in 3%. The corneae were examined in the healed state, when a high incidence (59%) were found to have superficial corneal dystrophies of the fingerprint lines, bleb, and Bietti's lacunar (map-like) types. These are considered individually, particular attention being paid to the distinction between the various types of line resembling the fingerprint line. Epithelial microcysts were also a common finding (59%) and were sometimes of the Cogan type. In only 11% of patients were there no corneal signs in the healed state. The need for careful examination of the cornea by retroillumination, using both the iris and the fundus, is stressed. The control group, in contrast, showed a very low incidence of dystrophies and cysts. Treatment was given initially with either drops or ointment and no differences in healing were found. Debridement was performed in 12 eyes as an initial treatment and also in four eyes which were not healing on medical treatment. Debridement assisted healing, but did not prevent recurrence. One eye was treated with debridement and scarification and seven with carbolization. These procedures appeared to reduce the recurrence rate. Sodium chloride ointment 5% was found useful as a prophylactic taken at bedtime, and the recurrence rate increased when it was withdrawn.

Adult↗
PubMed1976

Effects of fast neutrons on the eye.

The study of 93 eyes receiving neutron irradiation establishes the character of the ophthalmic complications of neutron. Significant changes are produced in the eyelids, conjunctiva, and cornea, but the production of cataract is relatively unimportant. No reaction was seen after neutron treatment that had not already been seen after chi or gamma radiation. That the unavoidable damage is similar to that reported with other forms of radiation, and not worse, is an important finding in view of the statistically significant benefit of neutron treatment to patients in a controlled clinical trial of advanced tumours of the head and neck (Catterall and others, 1975). The observations indicate that the improved cure rates with neutrons are not obtained at the expense of inflicting greater damage to normal structures. This investigation has also shown that the neutron effects of treating these very extensive tumours are acceptable and that, with carefully measured doses, they are predictable. The dose-response relationship in categories of clinical effect for a smaller series of patients, reported in Table 1 of our preliminary communication (Brown and other, 1976), is confirmed.

Adult↗
PubMed1976

Clinical manifestations secondary to soft contact lens wear.

The study of 151 patients wearing soft hydrophilic lenses for one year revealed no gross irreversible lesions with loss of vision. But of significance was the presence of superficial lesions of the corneal epithelium, and chronic stromal oedema. While no significant loss of wearing time was noted for women taking the pill, the decrease in tear secretion in those patients with a latent dry eye problem could just alter the balance to produce intolerance. From this report it is the long-term changes to the tissues that remain to be fully investigated for soft hydrophilic lenses.

Blepharitis↗
PubMed1976

Lowe's syndrome: identification of carriers by lens examination.

Lens examinations were performed on 7 obligate and 7 possible carriers of the X-linked gene for Lowe's syndrome, and on 117 controls. By quantitatively grading punctate cortical opacities, it was possible to discriminate between the obligate carriers and the controls with a fair degree of confidence. In the age group most important for genetic counselling, that of child bearing, the data are too limited for the derivation of precise estimates, but may, nevertheless, be useful. More such data are needed.

Adolescent↗
PubMed1975

Factors influencing the creep behavior of poly(methyl methacrylate) cements.

Room temperature compression creep and recovery tests have been performed using samples of pure poly(methyl methacrylate) (PMMA), three commercially available poly(methyl methacrylate) cements, and several experimental cements. From these tests the influence of density, mixing procedure, particle size, methyl methacrylate-styrene copolymer, barium sulfate, aquenous storage environments, residual monomer, molecular weight of the continuous phase, benzoyl peroxide, and N,N-dimethyl-paratoluidine, upon the creep behavior of PMMA cements has been determined. The important results is that lowering the porosity or residual monomer content, increasing the powder size, or adding an MMA-styrene copolymer tends to increase the creep resistance of PMMA cement.

Benzoyl Peroxide↗
PubMed1975

Dimensions of the human eye relevant to radiation protection.

An attempt has been made to clarify the two most important issues relevant to personal eye dosimetry. This involves the identification of the cells which are most at risk from radiation and the specification of their position in the eye. A survey of the radiobiological literature concerning animals and humans shows that the epithelial cells in the equatorial region of the lens are those which are involved in radiation cataract induction. The depth of these cells has been evaluated in the human eye by means of geometrical construction. The relevant dimensions have been determined from a survey of published anatomical data and supplemented by new data obtained by slit-image photography. In a normal adult population (20-65 years) the minimum depth of the incriminated cells is 2.3 plus or minus 0.4 mm; the upper and lower values are associated with young and old subjects respectively. Approximate calculations for isotropic 90Sr/90Y and 106Rh beta-radiation fields indicate that a planar dosemeter, which integrates the tissue dose between depths of 2.5-3.5 mm, should give a reasonable measure of the mean equatorial dose for the variety of eye and irradiation geometries likely to be met during a life-time exposure. The long established, but tentative, value of 3 mm for the effective depth of the lens is thus confirmed.

Adult↗
PubMed1975

Corneal rust removal by electric drill. Clinical trial by comparison with manual removal.

The dental burr rotated by an electric drill is the quickest, safest, and most precise form of treatment for corneal rust rings. It enables complete removal of the corneal rust at a single treatment and leaves a smooth crater that is no larger than the original rust ring. Pain relief is more rapid after electric drill removal; this is probably related to the complete removal of the rust. Epithelial and stromal healing are marginally faster than after manual removal and the patients' duration of attendance is less. The ideal drill is a slim straight instrument, which rotates dental burrs and is operated by a light finger pressure. A brake which stops drill rotation on lifting the finger is a useful safety feature.

Cornea↗