Biomedical subjects

R S Baird

Publications and source records attributed to R S Baird.

27 records · Page 2Linked to original sources

PubMed1980

Technical aspects of histamine determination in human tears.

We evaluated various technical aspects of tear collection to assess their influence on the measurement of tear histamine levels. We included several methods of collecting tears, storage of tears with and without freezing, storage for three vs ten days, and removal vs nonremoval of cells before freezing. We assayed tear samples in various groups of people with inflamed eyes. None of the various means of collecting or storing the tear samples influenced the histamine measured. The measuring technique is a stable one that requires minimal treatment of samples before assay. To date, we have found that only patients with vernal conjunctivitis have elevated tear histamine levels. Any increase of tear histamine over 10 ng/ml (geometric mean plus 2 S.D.) or any significant decrease is probably related to the disease itself and not to factors related to the technique used to measure tear histamine.

Biochemistry↗

PubMed1980

Tear histamine levels in vernal conjunctivitis and other ocular inflammations.

Histamine levels were measured in tears from normal volunteers (geometric mean, 5 ng/ml), patients with vernal conjunctivitis (16 ng/ml), and patients with a wide variety of external ocular inflammatory disease (3 ng/ml). Histamine levels were significantly higher in patients with vernal conjunctivitis than in normal subjects (P < 0.01) or patients with other types of ocular inflammation (P < 0.001). We postulate that histamine is an important mediator in the expression of the inflammatory response in vernal conjunctivitis, and that its elevation may be caused by abnormalities in the number of mast cells, the stability of the mast cells or in the system that regulates histamine.

Conjunctivitis↗

PubMed1980

Participation of ocular tissues in systemic anaphylaxis.

The participation of ocular tissues was examined in two models of systemic anaphylaxis in the rat. Increased retention of radiolabeled rat serum albumin, which accompanies anaphylaxis, was the parameter measured. The production of IgE antibodies to egg albumin or worm antigen was stimulated by immunization with minute amounts of egg albumin and alum or by infection with Nippostrongylus brasiliensis. Intravenous administration of egg albumin or worm extract produced clinical signs of systemic anaphylaxis in the correspondingly immunized rats. Systemic anaphylaxis was accompanied by increased retention of radiolabeled rat serum albumin in the small intestine in both groups of rats. Significantly increased retention occurred in rat lid-conjunctivaorbital tissues of both groups and in globe tissues of the rats immunized with egg albumin. We concluded that the ocular tissues participated in systemic anaphylaxis.

Albumins↗

PubMed1980

Degranulation of ocular mast cells in rats undergoing systemic anaphylaxis.

The percentage of degranulated ocular mast cells in five egg albumin--immunized, systemically challenged rats was compared with that in five egg albumin--immunized, saline-challenged controls. For the lid and orbit, at least 100 mast cells per rat were evaluated. For the conjunctiva, tarsus, limbus, and episclera-sclera, at least 20 were evaluated. For the ciliary body and choroid, all mast cells in 15 sections separated by at least 15 micrometer were examined. The morphology of degranulated and intact mast cells was the same in the experimental and control animals, except for the change in granules. There were significantly more degranulated mast cells in most of the ocular tissues of rats undergoing systemic anaphylaxis than in tissues of controls rats; the increase in degranulated cells was especially striking in the choroid. We concluded that degranulation of mast cells is a measure of anaphylaxis, provided that the number of degranulated mast cells, and not simply the presence of such cells, is considered and compared with appropriate controls.

Anaphylaxis↗

PubMed1979

Number of type of inflammatory cells in conjunctiva of asymptomatic contact lens wearers.

Biopsy specimens were taken from the upper tarsal conjunctiva of eight asymptomatic contact lens wearers and quantitative histology was determined and compared to histology from 15 normals and 55 patients with contact lens-induced giant papillary conjunctivitis. No abnormalities were detected in the asymptomatic contact lens wearers. One or more of the three tissue characteristics of giant papillary conjunctivitis--(1) mast cells in the epithelium, (2) eosinophils in epithelium or substantia propria, and (3) basophils in epithelium or substantia propria--was found in all patients with this syndrome, but none was present in any of the eight asymptomatic lens wearers. Trauma occurring over months or even years does not induce histologic alteration in the upper tarsal conjunctiva; the surface changes seen previously by scanning electron microscopy in asymptomatic lens wearers are secondary to trauma, not early aspects of the giant papillary conjunctivitis syndrome.

Adult↗

PubMed1979

Vernal conjunctivitis and contact lens-associated giant papillary conjunctivitis compared and contrasted.

We compared quantitative histologic counts of ten subjects with vernal conjunctivitis to counts of 15 subjects with contact lens-associated giant papillary conjunctivitis and to counts of 15 normal subjects. Both vernal conjunctivitis and contact lens-associated giant papillary conjunctivitis subjects had abnormalities of mast cells in the epithelium, and eosinophils and basophils in epithelium and substantia propria. No normal individuals had these abnormalities. An additional 28 subjects with ocular inflammatory conditions had tissue evaluation for abnormalities of mast cells, eosinophils, and basophils. A few eosinophils were found in four subjects. The histologic abnormalities of vernal conjunctivitis are shared by contact lens-associated giant papillary conjunctivitis but not by conjunctival inflammation in general. Vernal conjunctivitis and contact lens-associated giant papillary conjunctivitis may represent different subtypes of a general category of conjunctival abnormality characterized by giant papillae.

Adolescent↗

PubMed1979

Mass cells in ocular tissues of normal rats and rats infected with Nippostrongylus brasiliensis.

In orbital exenteration specimens from 14 rats, 93% of the mast cells were found in the lids, the limbus, and the conjunctiva, 5% in the orbital tissues, and less than 1% in the globe. The density of mast cells was highest in lid (2843/mm3), limbus (2822/mm3), and orbit (2184/mm3) and lowest in bulbar conjunctiva (794/mm3), ciliary body (512/mm3), and sclera (176/mm3). There was no significant difference in the distribution or density of mast cells in orbital exenteration specimens from normal rats compared with rats infected with the worm Nippostrongylus brasiliensis. We concluded that certain ocular structures are rich in mast cells, which suggests that these structures might be susceptible to injury mediated by mast cell products.

Animals↗

PubMed1978

Number of inflammatory cells in the normal conjunctiva.

We counted inflammatory cells per cubic millimeter in both the epithelium and the substantia propria of samples from upper tarsal conjunctiva of 15 normal subjects and from lower forniceal conjunctiva of ten normal subjects. The upper limit of normal for number of cells was nearly 500,000/mm3. Lymphocytes accounted for about 70% of the inflammatory cells. Neutrophils and lymphocytes were almost always present in both the epithelium and the substantia propria. Plasma cells and mast cells were present in the substantia propria of all subjects, but never in the epithelium. Neither eosinophils nor basophils were found in any specimen. We concluded that conjunctiva of the white and quiet eye usually contains heavy infiltrates of inflammatory cells.

Adolescent↗

PubMedDate not supplied

Edema test for assessing ocular anaphylaxis.

A technique for measuring the increase in conjunctival thickness which accompanies a clinically relevant, topically induced model of ocular anaphylaxis was developed and was compared with the determination of an increase in percent of degranulated mast cells in affected tissue. Twenty rats immunized with egg albumin were topically challenged with egg albumin solution applied to one eye and with phosphate-buffered saline applied to the other eye. Clinical signs of edema and erythema were not seen in ocular tissues undergoing anaphylaxis. However, both conjunctival thickness and percent of degranulated mast cells were significantly greater in antigen-challenged tissues than in buffer-challenged tissues. Amount of edema correlated significantly with amount of mast cell degranulation. Conjunctival thickness served as a reliable indicator of anaphylaxis. The measurement of topically induced anaphylaxis by evaluating the increase in conjunctival thickness was simpler, faster, and less expensive than the evaluation of anaphylaxis by the increase in the percent of degranulated mast cells in the same tissues.

Anaphylaxis↗