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Biomedical subjects

M F Smith

Publications and source records attributed to M F Smith.

288 records · Page 16Linked to original sources
PubMedDate not supplied

Associations between heterozygosity and morphological variance.

Recent studies have contrasted the expression of phenotypic traits, such as variance in morphological characters, with levels of genetic variation (heterozygosity) as determined by electrophoretic analysis of protein-coding loci. The theoretical basis for interpreting significant covariation stems in part from Lerner's work on genetic homeostasis, which predicts that within populations increased heterozygosity will produce decreased morphological variance, owing to a buffering effect of heterosis during development. However, the prediction for the relationship between genic heterozygosity and the variance of morphological traits among populations is unclear. To determine if a relationship existed between heterozygosity and morphological variance, we compared estimates of heterozygosity and morphological variance across 15 population samples of the fox sparrow and 17 samples of the pocket gopher. The estimates of morphological variance included coefficients of variation for each character and the variance of individual scores about the population mean in a principal components analysis. Although several recent studies have reported a significant relationship between heterozygosity and morphological variance, we found that the two measures do not covary significantly.

Animals↗
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A vectorized Monte Carlo code for modeling photon transport in SPECT.

A vectorized Monte Carlo computer code has been developed for modeling photon transport in single photon emission computed tomography (SPECT). The code models photon transport in a uniform attenuating region and photon detection by a gamma camera. It is adapted from a history-based Monte Carlo code in which photon history data are stored in scalar variables and photon histories are computed sequentially. The vectorized code is written in FORTRAN77 and uses an event-based algorithm in which photon history data are stored in arrays and photon history computations are performed within DO loops. The indices of the DO loops range over the number of photon histories, and these loops may take advantage of the vector processing unit of our Stellar GS1000 computer for pipelined computations. Without the use of the vector processor the event-based code is faster than the history-based code because of numerical optimization performed during conversion to the event-based algorithm. When only the detection of unscattered photons is modeled, the event-based code executes 5.1 times faster with the use of the vector processor than without; when the detection of scattered and unscattered photons is modeled the speed increase is a factor of 2.9. Vectorization is a valuable way to increase the performance of Monte Carlo code for modeling photon transport in SPECT.

Algorithms↗
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Reconstruction of the open mastoidectomy ear: a six year progress report.

This report deals with 61 mastoid cavities which were revised or reconstructed using homograft techniques over a six-year period. Discussed are the variety of homograft procurement techniques and surgical homograft techniques which have been abandoned and included in a review of 16 consecutive mastoid revisions performed from 1973-1974 utilizing a standard surgical technique.

Bone Transplantation↗
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Lyophilized partial ossicular replacement allografts.

This report deals with the use of partial ossicular replacement allografts (PORAs) in the stable ear, ie, a middle ear free of any residual or recurrent disease process such as fluid, cholesteatoma, or infection. PORAs have been used by Shinn and Smith at the Ear Medical Clinic of Santa Clara Valley between July 1978 and December 1981: they are used to span the distance between the malleus and the head of the stapes or tympanic membrane. Lyophilized ethylene oxide sterilized PORAs have been available through the Northern California Transplant Bank. San Francisco, since July 1978. Twenty-four of 32 PORAs (75%) used in stable ears closed the air-bone gap within 10 dB. Of the eight ears that did not have satisfactory functional hearing, it was evident within one year and there was no further deterioration noted up to four years. These was no evidence of PORA extrusion or erosion.

Ear Diseases↗
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1984 Santa Barbara state-of-the-art symposium on otosclerosis. Results, conclusions, consensus.

A state-of-the-art symposium on otosclerosis convened in Santa Barbara, California on Jan 6, 1984. The panel included some of the most distinguished and experienced otosclerosis surgeons in the world, with a collective experience of over 100,000 stapes operations. The purpose of the symposium was to develop guidelines for safe management of otosclerosis and to identify the at-risk patient for surgery. Topics included techniques developed by these surgeons through avoidance, recognition, and correction of technical problems; complications; and errors that lead to poor results. Discussed in order were patient evaluation, performance of surgery, and postoperative care.

Anesthesia, Local↗
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Management of the draining open mastoid cavity.

Deafness, discharge, dizziness, and dependency partially define the discomforts of the patient with an open draining mastoid cavity. The open mastoid cavity remains a problem for some patients despite visits to numerous otolaryngologists. This report is based on outpatient and surgical management of more than 300 open draining mastoid cavities.

Ambulatory Surgical Procedures↗
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Conservation of hearing in acoustic neurilemmoma excision.

Conservation of hearing in acoustic neurilemmoma surgery is possible by the suboccipital route. The hearing preservation prognosis decreases as the size of the cerebellopontine angle neoplasm increases. Von Recklinghausen disease spells a poor prognosis for hearing. Some hearing was retained in seven of ten patients with preoperative hearing. Three patients retained postoperative hearing levels and speech sound discrimination equal to preoperative levels. One patient had a progressive high-frequency sensorineural hearing loss in the nontumor ear and was fitted with a hearing aid for the postoperative ear; he now has successful binaural hearing function. Gentle technique, microhemostasis, special instrumentation, and well-developed surgical craft are essential for preserving the microstructures necessary for hearing. Furthermore, the suboccipital approach for neurilemmomas less than 2 cm gives good surgical exposure and a reasonable chance to save hearing.

Audiometry↗
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Treatment of postfiltration bleb leak by bleb injection of autologous blood.

We treated a persistent, brisk bleb-leak after trabeculectomy with mitomycin C by bleb injection of autologous blood. Following preparation with povidone iodine, approximately 0.5 cc of whole autologous blood was injected into the bleb at the slit lamp. The leak resolved after 36 hours, and after 9 months' follow up, continued to function well.

Aged↗
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Emergency access in pediatrics.

Obtaining i.v. access in children during an emergency situation is a challenge to nurses. It is important for the infusion nurse specialist to understand which devices and sites are appropriate in different circumstances. This article addresses the access sites and devices demanded in pediatric emergency situations and offers an approach to managing the anxiety of children requiring emergency infusion care and their families.

Age Factors↗