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Biomedical subjects

J D MacLeod

Publications and source records attributed to J D MacLeod.

13 recordsLinked to original sources
PubMed1998

Human mast cells express stem cell factor.

Stem cell factor (SCF) is a major cytokine regulator of mast cell growth and function. The present study demonstrates that human mast cells are able to produce SCF. Constitutive synthesis of SCF mRNA was seen in the mast cells isolated from human lung and skin by RT-PCR. This was confirmed by in situ hybridization in conjunctival mast cells of both tryptase-only (MCT) and tryptase/chymase (MCTC) subsets. SCF protein product was found in conjunctival MCT and MCTC mast cells by immunohistochemistry. Soluble SCF protein was detected in the culture supernatant of isolated lung mast cells by ELISA, and cross-linkage of IgE receptor (Fc epsilon-RI) on the lung mast cells in culture did not alter SCF mRNA expression, or the secreted soluble SCF protein. This was consistent with the finding that levels of SCF mRNA expression in conjunctival mast cells were similar between normal subjects and patients with seasonal allergic conjunctivitis (SAC). This study shows that human mast cells themselves are a cellular source of SCF, as well as being target cells for this growth factor. SCF may regulate mast cell growth and function via both paracrine and autocrine mechanisms. The production of SCF by mast cells may be regulated via mechanisms other than IgE receptor-mediated pathways.

Cell Culture Techniques↗
PubMed1997

Ocular pain: a casualty study. The spectrum and prevalence of pain in acute eye disease.

This study examined the prevalence and severity of ocular pain in eye casualty patients. All new patients presenting over a 1 month period were invited to indicate their pain level using a visual analogue scale. The results for 352 patients were analysed, and median pain levels calculated for 29 common diagnoses. Of those responding, 94% (= 47% of all new patients) had ocular pain at presentation. While many results were predictable, some diagnoses were associated with higher pain scores than expected. Junior ophthalmologists also were asked to indicate their perceptions of pain severity for the 29 diagnoses using the same visual analogue scale.

Acute Disease↗
PubMed1997

Seasonal allergic conjunctivitis is accompanied by increased mast cell numbers in the absence of leucocyte infiltration.

BACKGROUND: Seasonal allergic conjunctivitis (SAC) is the most common allergic disease to affect the eye, occurring alone or in association with allergic rhinitis. Infiltration with mast cells and eosinophils is characteristic of the chronic forms of allergic conjunctivitis such as vernal and atopic keratoconjunctivitis, and these cell types also contribute significantly to allergic inflammation in the skin. Indirect evidence for a similar pattern of cellular events in SAC comes from studies which demonstrate raised eosinophil and neutrophil numbers in conjunctival scrapings and elevated levels of mast cell tryptase in tears following allergen challenge. OBJECTIVE: To directly characterize the inflammatory cell infiltrate in SAC and to determine its clinical relevance. METHODS: We employed specific immunohistochemical staining to count mast cells, eosinophils and neutrophils in the conjunctival epithelium and lamina propria of eight atopic patients with SAC in, and 12 SAC patients out of the hay fever season. Sixteen patients with no history of ocular allergy were used as control subjects. RESULTS: Mast cells were absent from normal epithelium. During the pollen season median mast cell numbers in the lamina propria were found to be increased by 61% in patients with SAC compared with normals (P=0.012). Eosinophils were found in the lamina propria in less than half of the symptomatic patients with SAC and in only three patients were eosinophils present in the epithelium. The neutrophil numbers in the lamina propria of patients with SAC tended to be higher than normals but these changes did not reach statistical significance. CONCLUSION: These data based on the direct assessment of conjunctival tissue provide evidence that symptoms occur in SAC in the absence of detectable recruitment of eosinophils or neutrophils. This suggests that this disorder is related to mast cell-mediated changes.

Adult↗
PubMed1997

Bimedial rectus recession using the anchored hang-back technique.

Hang-back recession of a rectus muscle offers several advantages over conventional techniques: a reduced risk of scleral perforation, easy intraoperative adjustment, and a convenient site for suturing to the sclera. There are also disadvantages: the muscle tends to collapse, thereby increasing the effective recession and making the result less predictable. In addition, the insertion cannot accurately be displaced upward or downward, as may be required to correct A- and V-patterns, or vertical deviations. The authors describe a modified technique, an anchored hang-back recession, and discuss the results in 60 consecutive cases of bimedial rectus recession.

Amblyopia↗
PubMed1994

A new chart to improve the efficiency of glaucoma detection by oculokinetic perimetry.

Oculokinetic perimetry (OKP) has been proposed as a method to screen for glaucomatous visual field defects but its use is limited by a high false positive rate. The standard hand-held screening OKP chart uses 26 points. The spiral arrangement of numbers with this chart allows loci to be tested close to fixation but may contribute to the high false positive rate. We have therefore designed and assessed a simplified OKP chart with 22 numbers arranged circumferentially around a central target. The positions of the numbers are such that points between 12 degrees and 16 degrees from fixation are tested in all quadrants. Loci closer to fixation are not tested. Fifty eyes from 50 patients with glaucoma and 50 eyes from 50 patients with normal fields were tested with both charts. Of the patients with glaucoma 88% gave a positive result with the 26-point chart and 90% gave a positive result with the 22-point chart. The false positive rate of OKP in patients without field loss was 12% with the 26-point chart and 0 with the 22-point chart (0.02 > p > 0.01). We therefore propose a modification of the existing OKP chart which reduces the false positive rate in glaucoma detection.

Adult↗
PubMed1991

More than meets the eye: a study of the time lost from work by patients who incurred injuries from corneal foreign bodies.

A prospective study was carried out to establish the time lost from work due to corneal foreign body injury. Data were collected over a 5 month period on a total of 504 patients attending a busy district hospital eye casualty department. The median time lost through injury was 4 hours and 148 patients (30%) took no time off work. Corneal foreign bodies are known to be painful injuries but in spite of this few patients take more than half a day off work.

Absenteeism↗