Age-related alterations in the inflammatory response to dermal injury.

Previous studies have documented that the ability to heal wounds declines with age. Although many factors contribute to this age-associated deficit, one variable that has not been carefully examined is leukocyte recruitment and function in wounds. This investigation compares the inflammatory response in excisional wounds of young (age 8 wk) and aged (age 22 mo) mice. In the early inflammatory response, neutrophil content of wounds was similar for both aged and young mice. In contrast, macrophage levels were 56% higher in aged versus young mice (81 +/- 20 vs 52 +/- 13 cells per mm2). In the later inflammatory response, wounds of aged mice exhibited a delay in T cell infiltration, with maximum T cell levels at day 10 in aged mice versus day 7 in young mice. Despite this delay, the eventual peak concentration of T cells was 23% higher in the wounds of aged mice (152 +/- 11 cells per mm2 vs 124 +/- 21cells per mm2). The observed alterations in inflammatory cell content suggested that chemokine production might be altered with age. An elevation of monocyte chemoattractant protein (MCP-1) levels was observed in wounds of aged mice. RNase protection studies, however, revealed that the production of most chemokines, including MIP-2, MIP-1alpha, MIP-1beta, and eotaxin, tended to decline with age. Because optimal wound healing requires both appropriate macrophage infiltration and phagocytic activity, phagocytosis was examined. Compared to young mice, wound macrophages from aged mice exhibited a 37%-43% reduction in phagocytic capacity. Taken together, the data demonstrate age-related shifts in both macrophage and T cell infiltration into wounds, alterations in chemokine content, and a concurrent decline in wound macrophage phagocytic function. These alterations may contribute to the delayed repair response of aging.

Open-label crossover study of vitamin A ointment as a treatment for keratoconjunctivitis sicca.

The authors evaluated the efficacy of all-trans retinoic acid (vitamin A) ointment as a treatment for keratoconjunctivitis sicca (KCS) in a group of 11 patients selected on the basis of clinical history, slit-lamp examination results, rose Bengal staining, and tear film osmolarity. In this open-label crossover study, vitamin A ointment was no more effective than placebo in increasing tear secretion, as indicated by Schirmer test with proparacaine or tear film osmolarity, or in decreasing ocular surface disease, as indicated by rose Bengal staining. Seven patients stated some preference for the placebo ointment, two patients for the vitamin A ointment, and two patients had no preference.

Natural history of disease in a rabbit model for keratoconjunctivitis sicca.

We have continued our study of the tear film and ocular surface in our full KCS (keratoconjunctivitis sicca) rabbit model up to 52 weeks post-operatively. Tear film osmolarity remains elevated, conjunctival goblet cell density remains decreased, and the conjunctival epithelium remains abnormal. Corneal epithelial glycogen levels decreased progressively, and at 44 weeks post-operatively rabbits developed abnormal rose Bengal staining of the affected cornea that was shown to be associated with morphologic abnormalities at 52 weeks. Rabbits began rubbing the affected eye after the development of corneal staining. Our full KCS rabbit model demonstrates the features of the human disease.

Tear film osmolarity and ocular surface disease in two rabbit models for keratoconjunctivitis sicca.

We report the natural history of keratoconjunctivitis sicca (KCS) in two rabbit models. The first one (full KCS model) was created by closing the lacrimal gland excretory duct, and removing the nictitating membrane and harderian gland. We created the second one (lacrimal gland duct only [LGDO]-KCS model) by closing the lacrimal gland excretory duct. Although tear film osmolarity was abnormally high in both models, it was higher in the full KCS model. Decreases in corneal epithelial glycogen and in conjunctival goblet cell density, and morphological abnormalities of the conjunctiva correlated with increases in tear film osmolarity and duration of disease.

Stimulation of rabbit lacrimal gland secretion with biologically active peptides.

To determine whether biologically active peptides can stimulate lacrimal gland secretion, we measured fluid and protein secretion from the cannulated lacrimal gland excretory duct of anesthetized rabbits after arterial injection of various peptides. Vasoactive intestinal peptide (VIP, 0.003-3 nmol) and porcine histidine isoleucine-containing peptide (PHI, 0.01-3 nmol) stimulated fluid and protein secretion in a dose-dependent manner. Cholecystokinin octapeptide (CCK-8, 0.01-3 nmol) stimulated fluid but not protein secretion. Neither bombesin nor eledoisin in doses as high as 3 nmol stimulated fluid or protein secretion. When combinations of high or low doses of VIP and the cholinergic agonist acetylcholine (ACh) were injected simultaneously, fluid and protein secretion was additive. We concluded that VIP and PHI stimulated secretion of lacrimal gland fluid and protein, CCK-8 stimulated secretion of fluid, and bombesin and eledoisin did not stimulate either fluid or protein secretion. VIP and ACh, both found in lacrimal gland nerve endings, stimulate lacrimal gland fluid and protein secretion by separate pathways.

A new rabbit model for keratoconjunctivitis sicca.

The authors created a new rabbit model for keratoconjunctivitis sicca by cauterizing the lacrimal gland excretory duct and surgically removing the nictitating membrane and harderian gland. Although the slit-lamp examination findings remained normal for the first 8 wk postoperatively, tear-film osmolarity was elevated by postoperative day 1. Corneal epithelial glycogen levels declined progressively, and conjunctival goblet cell density remained decreased. Multiple controls indicated that closure of the lacrimal gland excretory duct was required for elevation of tear film osmolarity, which, in turn, was required for persistent ocular surface disease.

Improved technique for storage of tear microvolumes.

The authors have developed an improved technique for storage of fluid microvolumes prior to osmolality measurement. To date, tear samples have been stored in a column of Cargilles B immersion oil contained within a capillary tube, sealed at one end with Critoseal. Covering the open end of this tube with Parafilm now provides reliable storage of 0.5-microliter samples for up to 24 hr; using water-saturated Cargilles B immersion oil within the capillary tube, and covering the open end of the tube with Parafilm now provides reliable storage of 0.1-microliter samples for up to 18 hr.

A proposed mechanism for increased tear-film osmolarity in contact lens wearers.

Contact lenses decrease corneal sensitivity and increase tear-film osmolarity. To determine whether the decrease in corneal sensitivity is responsible for the increase in tear-film osmolarity, we studied tear-film osmolarity in normal rabbits and rabbits with surgically induced keratoconjunctivitis sicca before and after the instillation of 0.5% proparacaine. Instillation of proparacaine resulted in a significant increase in tear-film osmolarity. Decreased corneal sensitivity, with a resultant decrease in tear secretory rates, is the most likely cause for increased tear-film osmolarity in wearers of hard contact and extended-wear soft contact lenses.

Prenatal exposure to the fungicide dinocap causes behavioral torticollis, ballooning and cleft palate in mice, but not rats or hamsters.

The present study is an evaluation of the developmental toxicity of dinocap in three rodent species using an in vivo teratology screen. Our protocol uses postnatal viability, weight gain, and morphological and behavioral development through weaning to assess the developmental toxicity of compounds. Dinocap administered orally on days 7 to 16 of gestation to the CD-1 mouse resulted in increased postnatal mortality at 25 mg/kg/d (80% in block 1 and 40% in block 2). Many of the treated pups that died during the neonatal period were "ballooned" and had cleft palates. Although there was no treatment related mortality in the 12 mg/kg/d dosage group, 6% (14/226) of these mice and 24% (23/96) of the survivors from the 25 mg/kg/d dosage group displayed torticollis (a twisting of the neck resulting in an abnormal tilting of the head). These tilted-head mice held the head and forepart of the body tilted constantly to one side, both when resting and walking. The tilt was in either direction but was always constant for a given animal; in different mice, the angle varied considerably from almost 0 to 30 degrees. Some mice circled repeatedly in one direction in the home cage, others bobbed their heads and did back-flips, while others rolled over, always rolling in the same direction. In the hamster, developmental toxicity was seen at (100 and 200 mg/kg/d) or near (50 mg/kg/d) maternally toxic doses but no behavioral alterations were noted and none of the pups were ballooned.