Among the three adult sheep hemoglobins (A, B, and C), two (A and B) are reportedly products of alleles. The beta-chains of A and B differ by at least seven scattered amino acid residues whereas the beta-sequence of C differs from A by at least 16 residues and from B by at least 21 residues. These changes suggest that the origin of C-beta antedated the divergence of A and B. Five shared differences between A-beta and C-beta with respect to B-beta can be interpreted as the result of selective advantage in favor of B. A complex of additional mechanisms has possibly been involved in maintaining the A-B- C porymorphism.
The records of 56 patients presenting with mucoceles and/or pyoceles have been reviewed. The most frequent complaints recorded were frontal headaches, eye problems, postnasal discharge, frontal sinus tenderness, and fluctuant swellings of the forehead. Roent-genographic studies demonstrated a high incidence of orbital roof erosion and anterior frontal sinus table erosion. Posterior frontal sinus table erosion and osteomyelitis were also demonstrated. In about half of the cases there was x-ray evidence of clouding of the frontal sinus. In one third of the patients a soft tissue mass could be demonstrated in the frontal sinus. Osteomas were reported in the frontal sinus in four cases. Surgery employed included the Macbeth osteoplastic procedure, the Goodale osteoplastic operation, the Lynch-Howarth operation, the radical frontal sinuseetomy with sinus collapse, and a local incision of a small mucocele. Analysis of the results indicates that the collapse operation had the greatest success, with only one recorded failure. Surgical revision of nine failures successfully eradicated the disease. The most frequent predisposing factors to mucocele formation were previous frontal sinus infection, previous surgery involving the frontal sinus including neurosurgical procedures that violated the sinus, external trauma to the sinus, long standing nasal allergy, and osteomas in the nasofrontal area of the sinus. The average interval between the primary insult to the frontal sinus and surgical confirmation of the frontal sinus mucocele was seven and one-half years. Such a lapse of time makes the establishment of the cause of mucocele formation in the frontal sinus difficult and short term evaluation of the surgery for their eradication uncertain. It would appear that the ultimate relief of the condition will lie in the hands of the surgeon.
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