No correlation between multi-locus heterozygosity and fitness in the common buzzard despite heterozygote advantage for plumage colour.

Correlations between heterozygosity and fitness are frequently found but rarely well understood. Fitness can be affected by single loci of large effect which correlate with neutral markers via linkage disequilibrium, or as a result of variation in genome-wide heterozygosity following inbreeding. We explored these alternatives in the common buzzard, a raptor species in which three colour morphs differ in their lifetime reproductive success. Using 18 polymorphic microsatellite loci, we evaluated potential genetic differences among the morphs which may lead to subpopulation structuring and tested for correlations between three fitness-related traits and heterozygosity, both genome wide and at each locus separately. Despite their assortative mating pattern, the buzzard morphs were found to be genetically undifferentiated. Multilocus heterozygosity was only found to be correlated with a single fitness-related trait, infection with the blood parasite, Leucocytozoon buteonis, and this was via interactions with vole abundance and age. One locus also showed a significant relationship with blood parasite infection and ectoparasite infestation. The vicinity of this locus contains two genes, one of which is potentially implicated in the immune system of birds. We conclude that genome-wide heterozygosity is unlikely to be a major determinant of parasite burden and body condition in the polymorphic common buzzard.

Retinal ependymoma: an immunohistologic and ultrastructural study.

Glial tumors of the retina are rare. Most are syndrome associated and include pilocytic astrocytoma in neurofibromatosis type 1 and subependymal giant cell astrocytoma in tuberous sclerosis complex. Acquired, more conventional, diffuse astrocytomas are less frequent. Ependymoma is exquisitely rare. Herein, we report the clinicopathologic features of the second case of retinal ependymoma. The tumor was sporadic in occurrence and unilateral, low grade, and of cellular type. Its chronic course and large size prompted an initial pathologic diagnosis of "massive retinal gliosis." The literature regarding retinal glial neoplasia including ependymoma as well as the so-called massive retinal gliosis is discussed.

Treatment of facial palsies with external eyelid weights.

PURPOSE: Because ocular exposure is a major complication of facial paralysis, an external gold eyelid load weight was evaluated for effectiveness in the treatment of this problem. METHODS: We prospectively studied 12 patients with unilateral facial paralysis who were treated with the external eyelid weights. Follow-up examinations included corneal exposure, amount of artificial tear usage, patient comfort, and complications associated with the weights. Treatment end points were the patient's decision to undergo a canthoplasty or placement of an implanted weight or resolution of the facial paresis to better than House's grade IV/VI. RESULTS: Of the 12 patients studied, ten had decreased corneal exposure on the affected side, with a coincident decrease in artificial tear drop use and increased comfort. One patient had no improvement in a corneal defect, and one was unable to apply the weight. Five patients had some difficulty in positioning the weight, which was related to upper eyelid dermatochalasis in four of the five. Only two weights were lost in over two years of total wearing time. CONCLUSIONS: External eyelid weights are useful in the treatment of ocular exposure associated with facial paralysis. The weights decreased corneal exposure, decreased reliance on artificial tear drops, and increased patient comfort. The weights were helpful as a trial before implantation of eyelid weights and as a longer-term treatment for ocular exposure in patients with temporary facial paralysis. Loose upper eyelid skin may limit their usefulness in some patients.

Congenital absence of the lacrimal puncta.

We report seven cases of congenital absence of the lacrimal puncta, a condition that may be either an isolated finding or associated with other developmental anomalies. General pediatric evaluation of two patients with punctal agenesis revealed no additional abnormalities; these cases were managed by probing and silicone intubation. The other five cases were associated with other significant, clinically obvious abnormalities; several of these patients required more aggressive management of their lacrimal disorders, including dacryocystorhinostomy and conjunctivo-dacryocystorhinostomy. Previous reports support the impression generated by this series that otherwise normal appearing children with congenital absence of the lacrimal puncta do not require an extensive work-up. Probably many children with absent puncta are asymptomatic and remain undiagnosed.

Etiology and management of facial palsy.

Palsy of the facial nerve can result in severe debilitation. The physical disfigurement has a disastrous effect on self-image. Asymmetry of facial expression, drooling, and difficulty with speech may occur. Additionally, impaired closure of the eye can result in exposure of the cornea with not only discomfort, but also loss of vision. If the nerve injury is proximal, loss of salivation, lacrimation, and changes in taste can occur. Clearly, an understanding of facial palsy and a framework for management are needed by the clinician who encounters this condition. The recent literature is surveyed for various causes of seventh nerve palsy and for therapeutic modalities available to the physician.

Hydatid disease in a horse.

During routine necropsy of a 28-year-old horse with intestinal volvulus, numerous hydatid cysts were discovered in the liver. Viable protoscolices of Echinococcus granulosus were obtained from the cyst. As a 4-year-old, this horse had been imported from an area that is enzootic for equine hydatidosis.