Orientation of homing pigeons altered by a change in the direction of an applied magnetic field.

Homing pigeons were equipped with a pair of small coils around their heads. Birds with an induced field of 0.6 gauss and the south magnetic pole up, oriented toward home normally under both sun and overcast. Birds with the polarity reversed oriented toward home when the sun was visible but often flew away from home under overcast.

Analysis of a circular derivative of Saccharomyces cerevisiae chromosome III: a physical map and identification and location of ARS elements.

DNA was isolated from a circular derivative of chromosome III to prepare a library of recombinant plasmids enriched in chromosome III sequences. An ordered set of recombinant plasmids and bacteriophages carrying the contiguous 210-kilobase region of chromosome III between the HML and MAT loci was identified, and a complete restriction map was prepared with BamHI and EcoRI. Using the high frequency transformation assay and extensive subcloning, 13 ARS elements were mapped in the cloned region. Comparison of the physical maps of chromosome III from three strains revealed that the chromosomes differ in the number and positions of Ty elements and also show restriction site polymorphisms. A comparison of the physical map with the genetic map shows that meiotic recombination rates vary at least tenfold along the length of the chromosome.

Aortic endothelial mitosis and Evans blue uptake in cholesterol-fed subscorbutic guinea-pigs.

SUMMARY: Groups of ovalbumin sensitised, subscorbutic guinea-pigs were subjected to various regimens for 8-10 weeks. Group 1 were given 0.25 mg/100 g body wt. cholesterol by mouth daily and were stressed with intraperitoneal injections of ovalbumin twice weekly. Group 2 received the cholesterol only and Group 3 were stressed only. Group 4 on the low vitamin C diet only acted as controls. Evans blue uptake tests and tritiated thymidine autoradiographs of Häutchen preparations of aortic endothelium were made on each animal. Endothelial mitosis was greatest in those areas of the aorta that had taken up the Evans blue most avidly. This was most apparent in Group 1, though to a lesser extent in Groups 2 and 3 also. Group 4 showed no dye uptake and the mitotic index was not raised. Blood ascorbic acid and plasma cholesterol levels are given for the various groups.

The mouse intestinal fatty acid binding protein gene: nucleotide sequence, pattern of developmental and regional expression, and proposed structure of its protein product.

The rat intestinal fatty acid binding protein (I-FABP) gene has been used as a model to study temporal and spatial differentiation of the gut epithelium while its protein product has been used as a model for examining the atomic details of noncovalent fatty acid-protein interactions. We have isolated the mouse I-FABP gene (Fabpi) and determined its nucleotide sequence. Comparisons of the orthologous mouse, rat, and human I-FABP genes revealed three conserved domains in their otherwise divergent 5' nontranscribed sequences. RNA blot hybridization and multilabel immunocytochemical methods were used to compare the developmental stage-specific patterns of activation of the rat and mouse genes. In addition, Fabpi expression in enterocytes was examined as a function of their differentiation along the crypto-to-villus and duodenal-to-colonic axes of the small intestine. Based on the similar temporal and geographic patterns of mouse and rat I-FABP expression described here and the results of our earlier studies of transgenic mice containing rat Fabpi/human growth hormone fusion genes, we propose that one of the conserved domains, spanning nucleotides -500 to -419 in mouse Fabpi, and/or a 14-bp element, are necessary for establishing and maintaining its region-specific expression along the duodenal-to-colonic axis of the perpetually renewing gut epithelium. Finally, predictions of the structure of mouse I-FABP using the refined 2.0 A model of rat I-FABP, suggest that a proline found at position 69 of the mouse, but not rat, protein may affect its ligand binding properties.

The career impact of keratoconus on Air Force aviators.

Keratoconus causes progressive blurring and distortion of vision, which threatens the career of a military aviator. To assess the impact of keratoconus on flying careers, we reviewed the records of all aviators with keratoconus who have been examined at the United States Air Force School of Aerospace Medicine over the past 23 years. Of the 22 aviators observed for more than three years, 18 were still qualified to fly at their most recent examination. The remaining four aviators were permanently removed from flying duties because of visual dysfunction caused by keratoconus. Of the 22 aviators examined, 15 required hard contact lenses for optimal correction of vision. No aircraft accidents or incidents, attributable to visual factors, were documented. We concluded that the majority of aviators with keratoconus are able to continue their flying careers safely with the aid of spectacles or contact lenses.

Cervical tracheoesophageal fistula.

Four unusual cases of cervical tracheoesophageal fistula (TEF) are presented. The incidence, diagnosis and treatment of cervical TEF are discussed. Surgically, if the location is above the level of T2 a cervical approach may be utilized. The cases included a cervical "H" type TEF occurring in an adult. Congenital "H" type TEFs frequently occur in the neck. An adult presenting with a cervical "H" type TEF, having as an infant undergone repair of a thoracic TEF, is unique. Two layer closure of both trachea and esophagus with strap muscle interposition is preferred. The other cases include a TEF secondary to metastatic breast carcinoma, one associated with a stomal recurrence, and an acquired TEF following laryngectomy. Metastatic breast carcinoma resulting in a TEF is reported for the first time. Malignant TEF's are usually secondary to carcinoma of the esophagus, lung, or thyroid. Best palliation is achieved either by esophageal intubation, by colon bypass, or by gastric pull-up with esophageal exclusion. Stomal recurrence with TEF following laryngectomy is treated with one-stage resection and reconstruction with a pectoralis major myocutaneous flap and gastric pull-up. A patient 5 years post-laryngectomy illustrates an acquired non-malignant cervical TEF, a category which includes fistulas due to trauma, tracheotomy, or endotracheal tubes, instrumentation, and inflammatory disease. Prompt surgical closure as in congenital cases is the treatment of choice although select cases require medical therapy.

Superior rhinotomy for en bloc resection of bilateral ethmoid tumors.

Ethmoid sinus neoplasms have traditionally been associated with a poor prognosis. Their advanced stage at presentation and proximity to vital structures have made them difficult to treat. Bilateral ethmoidal tumors impinging on or actively infiltrating the cribriform plate have been particularly resistant to cure. We have used the superior rhinotomy in conjunction with a bifrontal craniotomy in three patients to effect an en bloc resection of both ethmoid labyrinths and cribriform plate in an oncologically acceptable fashion.

Surgical treatment of blindness secondary to intraorbital hemorrhage.

Rapid progression to blindness due to intraorbital hemorrhage following various forms of trauma requires immediate, aggressive intervention, with the potential to restore vision. Orbital decompression via either an external ethmoidectomy or transantral approach is described. The diagnosis, anatomy, and pathogenetic mechanisms relevant to these cases are reviewed.

Surgical therapy of chronic mastoiditis with cholesteatoma.

One hundred fifty-seven ears treated surgically for chronic mastoiditis with cholesteatoma are reviewed. The selection of an operative procedure ("canal wall up" or "canal wall down") was dictated by the extent of pathologic indications in relation to the size of the patient's mastoid. The incidence of recurrent or residual cholesteatoma, the hearing results, and the frequency of visits required for mastoid cavity care are reported.

Tonsillectomy and adenoidectomy: changing trends.

A review of 1,722 tonsil and adenoid procedures performed between 1978 and 1986 is presented. Each year there has been a progressive decrease in the number of procedures performed; the incidence of adenoidectomy has declined particularly. Although infection remains the predominant indication for surgery, there has been a dramatic rise in obstructive sleep apnea as a significant indication, from 0% in 1978 to 19% in 1986. At present, this trend promises to continue as physicians become increasingly aware of the prevalence and seriousness of adenotonsillar hypertrophy as a cause of sleep apnea, particularly in the general pediatric population.

Retinal detachment in U.S. Air Force flyers.

Retinal detachment is a serious ocular condition, even though 85% can be repaired permanently. Long-term complications include decreased or loss of vision, redetachment, visual field changes, and proliferative vitreoretinpathy. To assess the effect of retinal detachment on flying careers, we reviewed the records of all aviators with a rhegmatogenous retinal detachment who were examined by the Ophthalmology Branch of the Aerospace Medicine Directorate at the Armstrong Laboratory (formerly the USAF School of Aerospace Medicine) from 1967-1986. Of the 19 flyers, 12 were returned to flying duties; only 2 were disqualified for ocular reasons alone. In 10 flyers, the detachments were previously undiagnosed. Associated vitreoretinal pathology was common in both eyes (42%). All received some type of treatment. Redetachment occurred in 4 flyers, but the overall final reattachment rate was 95%. Final posttreatment visual acuities were 20/20 or better in 16 flyers. Treatment-induced myopia was common. Many flyers enjoyed long flying careers after detachment repairs.

A survey of U.S. Air Force flyers regarding their use of extended wear contact lenses.

We reviewed the USAF Tactical Air Command's (TAC) contact lens database for the period July 1989 through June 1991. An anonymous survey was mailed to 396 TAC aircrew members in February 1992 to assess their experiences using extended wear soft contact lenses (EWSCL). Analysis was performed on those responses to compare differences between aviators who currently wear (CW), those who discontinued wear (DCW), and flyers who wore EWSCL while deployed to S.W. Asia for Desert Shield/Desert Storm. Of the 396 surveyed, 284 (72%) returned the survey and demonstrated that the daily use of EWSCL to be logistically practical and physiologically safe. No ocular malady was reported that would preclude continued use by aircrews. Desert Shield/Storm experiences documented that the use of EWSCL by USAF aircrews in a desert environment was possible. Logistical difficulties for the small number who either deployed with inadequate supplies or required replacement lenses were shown to be the primary challenge to the wear of EWSCL during Desert Shield/Storm. Subjectively, aircrews expressed strong beliefs that EWSCL contributed to their abilities as combat aviators.

Cataract surgery and intraocular lenses in military aviators.

We reviewed the medical records of 23 military aviators who were evaluated by the United States Air Force School of Aerospace Medicine (USAFSAM) after cataract extraction with intraocular lens implantation between 1979 and 1990. The 23 subjects were male Caucasians, with a mean age of 43 years. Of the subjects, 21 were pilots, and, of these, 8 were qualified in high-performance aircraft. There were a total of 28 operated eyes, 24 of which had received extracapsular cataract extractions (ECCE) with posterior chamber lenses. The best-corrected, postoperative vision was 20/20 or better in all eyes. Posterior capsule opacification occurred in 14 (60%) of the ECCE eyes, with five requiring Nd:YAG (Yttrium-Aluminum-Garnet) laser capsulotomies. One aviator was disqualified from flying duties because of ocular deficiencies, for a visually-qualified-to-fly rate of 96%. Eight aviators have actually flown since surgery. Although follow-up was short, the initial results are encouraging.

The pigmentary dispersion disorder in USAF aviators.

The pigmentary dispersion syndrome (PDS) can have serious ocular consequences. Visual changes due to glaucoma and the treatment required can threaten the high level of visual function necessary in military aviation. We reviewed the records of 50 aviators with PDS who were evaluated at the Aeromedical Consultation Service (formerly the USAF School of Aerospace Medicine) over the past 10 years. At last evaluation, 48 were still qualified to fly. Only two aviators were permanently removed from flying duties due to glaucoma. Initial intraocular pressures, cup-to-disc ratios, and refractions were not statistically correlated with progression to glaucoma, but sample sizes were small. At final evaluation, 20 of the 34 aviators with follow-up had glaucoma and required medication. Thirteen eyes underwent laser trabeculoplasty. With appropriate management, the majority of aviators with PDS were able to safely continue their flying careers.

Retinal vein occlusions: case reviews of USAF aviators.

Retinal vein occlusions are primarily a disease of the elderly, frequently with permanent visual abnormalities. However, both branch and central retinal vein occlusions occur rarely in young individuals. Reported here are a series of retinal vein occlusions in USAF aviators. Seven cases were identified from records of the USAF Armstrong Laboratory Aeromedical Consultation Service from 1976-91. Four cases of central retinal vein occlusions and three cases of branch occlusions are summarized. Initial visual acuity ranged from 20/15 to 20/400. All seven aviators recovered 20/15 vision and returned to flying status. Hyperlipidemia was found in four of the seven aviators, and hypertension was diagnosed in two aviators. Included is a discussion of current concepts in the natural history, associated systemic conditions, treatment options, and aeromedical implications of retinal vein occlusions.

The medical acceptability of soft contact lens wear by USAF tactical aircrews.

Seventy-two Tactical Air Command (TAC) aircrew members completed one full year of soft contact lens (SCL) wear. A daily-wear regimen, using extended-wear lenses, was used to minimize corneal stress. Baseline measurements of visual acuity with SCLs and with spectacles after SCL removal and ocular indicator gradings were compared to measurements at 5-d, 10-d, 1-month, 3-month, 6-month, and 12-month examinations. Visual acuity did not decrease during the test. No aircrew member developed corneal ulcers or other serious complications requiring elimination from the test. Two aircrew members lost a total of 9 "duties not to include flying" (DNIF) days: one flyer was grounded for 1 d with a corneal abrasion and another for 8 d with epithelial microcysts. The TAC SCL Test, as designed, was generally successful. The conservative approach to SCL wear during the test and the meticulous follow-up care by United States Air Force eye care professionals most likely contributed to the low ocular complication rate.

Prescribing spectacles for aviators: USAF experience.

This special report was written for USAF vision specialists to use as a guide when prescribing spectacles for military aviators and to extend to the civilian sector the knowledge gained from the USAF experience. Visual correction in aviators presents some unique problems, especially for presbyopes. The demands of each individual aircraft environment need to be well understood. Ophthalmologists and optometrists must consider all pertinent aeromedical factors before prescribing spectacles for ametropic aviators.

Central serous chorioretinopathy in U.S. Air Force aviators: a review.

Idiopathic central serous chorioretinopathy (ICSC) is an uncommon disease with the potential to cause loss of visual acuity, decreased color vision, and decreased depth perception. These visual changes may become permanent and require removal of aviators from flight status. This study reviews 55 eyes of 47 USAF aviators with ICSC examined at the United States Air Force School of Aerospace Medicine (USAFSAM), Brooks AFB, TX. Clinical and aeromedical findings, both on initial and on follow-up ophthalmic examination were studied. Ninety-seven percent of aviators otherwise medically qualified were ultimately returned to flight status. Overall, 51% had recurrent episodes, 17% had bilateral disease, and 13% underwent laser photocoagulation. Visual acuity correlated with active disease, and there was a trend toward poor stereopsis and diminished color vision with worsening visual acuity. Eighty-six percent attained a final visual acuity of 20/20 or better. On final examination, 90% had normal stereopsis, 87% had normal color vision, and 49% had a normal central visual field. Eyes with recurrent disease tended to have degraded final visual acuity, stereopsis, color vision, and central visual field. The visual and aeromedical prognosis from a single attack of ICSC is generally favorable, but repeated attacks can lead to a significant decrease in visual functions that may jeopardize flying status.