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Biomedical subjects

M A Callahan

Publications and source records attributed to M A Callahan.

13 recordsLinked to original sources
PubMed1989

Mohs micrographic surgery for periorbital skin cancer.

The authors have illustrated the use of the Mohs technique on periorbital skin cancer. The indications for the technique are documented for eyelid and canthal neoplasia, and the case histories illustrate the potential danger of skin cancer in this area. It is the well balanced team of micrographic surgeons and reconstructive surgeons that will give the patient the best result.

Adult↗
PubMed1979

"Congenital" hematic cyst of the orbit.

A case of true hematic cyst of the orbit in a 10-year-old girl, apparently resulting from birth trauma, is presented. Ultrasonic and clinical features believed to aid the examiner in correctly diagnosing such a lesion are presented. While apparently unique among reported cases, "congenital" hematic cysts of the orbit undoubtedly occur occasionally and the possibility of this entity should be considered in appropriate circumstances.

Birth Injuries↗
PubMed1979

Ultrasonically-aided percutaneous orbital aspiration.

Ultrasonography is the most effective diagnostic modality for locating and delimiting cystic orbital lesions, and may often provide an accurate tissue diagnosis. A case is presented demonstrating the ability of ultrasonography to aid in the percutaneous aspiration of selected orbital cystic lesions.

Adolescent↗
PubMed1979

Conjunctival flap.

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Cataract Extraction↗
PubMed1978

Correlation between phosphorylated H1 histones and satellite DNAs in Drosophila virilis.

Drosophila virilis DNA contains satellites I, II, and III. D. novamexicana DNA contains satellite I. D. virilis H1 histone contains subfractions a, b, c, d, and e; D. novamexicana H1 contains subfractions a, b, and c. Therefore, satellites II and III might be correlated with H1d and H1e. To test the validity of this correlation, the H1 histones of polytene nuclei, which contain less than 1% satellite DNA, were analyzed. Polytene nuclei of D. virilis contain substantially decreased levels of H1c and H1e and marginally decreased levels of H1d. Polytene nuclei of D. novamexicana contain decreased levels of H1c.H1c is correlated with satellite I (common to D. virilis and D. novamexicana); H1e is correlated with satellites II and III; H1d is not correlated with any satellite DNA, because its level is virtually unchanged in polytene cells lacking detectable amounts of satellite DNA. Alkaline phosphatase digestion of the H1 histones reveals that H1c is the phosphorylated form of H1b and H1e is the phosphorylated form of H1d. Therefore, the under-replication of satellite DNAs is correlated with the decreased phosphorylation of H1 histones. In vitro, D. virilis H1 histones preferentially bind D. virilis DNAs in the progression III greater than II greater than I greater than main band, whereas D. virilis core histones do not preferentially bind any D. virilis DNA. As an extension of these results, we suggest that phosphorylated H1 histones bind D. virilis satellite DNAs in vivo and are involved in the compaction of heterochromatin.

Alkaline Phosphatase↗
PubMed1976

Slit-beam ruler.

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Corneal Ulcer↗
PubMed1976

Synthetic absorbable suture for strabismus surgery.

Polyglactin 910 (Vicryl), a synthetic absorbable braided suture in 5-0 or 6-0 size, was satisfactory for recession and resection of extraocular muscles. It produced an acute allergic reaction in only one of 89 cases (1.5%) as compared to a 19% reaction when collagen suture of like size was used. Polyglactin 910 suture, when left partially exposed, may be irritating and can cause excessive reaction when used at the conjunctival limbus.

Collagen↗
PubMedDate not supplied

Role of exposure databases in risk assessment.

Risk assessments have assumed an increasingly important role in the management of risks in this country. The determination of which pollutants or public health issues are to be regulated, the degree and extent of regulation, and the priority assigned to particular problems are all areas of risk assessment that influence the country's $100 billion annual investment in environmental protection. Recent trends in public policy have brought the practice of risk assessment under greater scrutiny. As policy makers increasingly insist that specific numerical risk levels (so-called bright lines) be incorporated into regulatory decisions, the stakes for good risk assessment practice, already high, are raised even further. Enhancing the scientific basis of risk assessments was a major goal of the Workshop on Exposure Databases. In this article, we present the Risk Assessment Work Group's evaluation of the use of exposurerelated databases in risk assessment and the group's recommendations for improvement. The work group's discussion focused on the availability, suitability, and quality of data that underly exposure assessments, a critical component of risk assessment. The work group established a framework for evaluation, based on exposure scenarios typically used in regulatory decisions. The scenarios included examples from Superfund, the Clean Air Act, the Toxic Substances Control Act, and other regulatory programs. These scenarios were used to illustrate current use of exposure data, to highlight gaps in existing data sources, and to discuss how improved exposure information can improve risk assessments. The work group concluded that many of the databases available are designed for purposes that do not meet exposure and risk assessment needs. Substantial gaps exist in measurements of actual human exposure and in the data necessary to model exposures, to characterize distributions of exposure, to identify high-risk groups, and to identify possible environmental inequities in exposure. The work group, on the basis of its findings, made both short-term and longer-term recommendations for improving the collection of exposure data in the future.

Animals↗
PubMedDate not supplied

Correction of facial contour deformities resulting from loss of soft tissue or bone.

Two methods of recovering normal contour of the orbit are presented in which ocularists and ophthalmologists equally participate. One method is for correction of the deep supratarsal retraction following soft tissue atrophy; the other technique is indicated when there has been loss of or major displacement of bone of the orbital rim. Frequently, these two techniques must be used concomitantly in complex reconstructive cases.

Adolescent↗