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Biomedical subjects

T McMullen

Publications and source records attributed to T McMullen.

At least 19 recordsLinked to original sources
PubMed1998

A lattice model for computing the transmissivity of the cornea and sclera.

The method of photonic band structure is used to calculate the frequencies of light that propagate in lattice models of the cornea and sclera of the mammalian eye, providing an explanation for transparency in the cornea that first properly accounts for multiple scattering of light. Each eye tissue is modeled as an ordered array of collagen rods, and photonic band structure methods are used to solve Maxwell's equations exactly for these models, a procedure that automatically effectively includes all orders of multiple scattering. These calculations show that the dispersion relation for the cornea is linear in the visible range, implying that the cornea is transparent. We show that the transmissivity is approximately 97% by using an effective medium approximation derived from the photonic band structure results and applicable in the visible region. In contrast, the dispersion relation for the model in the sclera is not linear in the visible region, and there are band gaps in this region that could play an important role in the transmission of light in the sclera.

Animals↗
PubMed1996

Ambulatory Gynecologic Surgery

A retrospective study evaluated the feasibility and safety of operative gynecologic procedures performed in an ambulatory surgical center. Between July 1993 and December 1995, 5766 women (mean age 36.9 yrs, range 13-95 yrs) who were referred to our center underwent surgery. The most common preoperative diagnoses were dysfunctional bleeding, missed abortion, postmenopausal bleeding, cervical dysplasia, mullerian duct malformation, infertility, endometriosis, adhesions, desire for sterilization, adnexal mass, lower abdominal pain, ectopic pregnancy, and fibroids. A total of 2351 laparoscopies, 2 laparotomies, and 3415 vaginal procedures were performed. The most common procedures were dilatation and curettage, 1455; hysteroscopy, 1051; adnexal surgery, 810; tubal ligation, 679; abdominal myomectomy, 186; operative hysteroscopy, 145; and cone biopsy, 118. The duration of surgery was 10 to 210 minutes. Most patients (99.51%) were discharged between 2 and 8 hours after surgery. Only 28 (0.49%) had to be admitted to the hospital; 18 women had preoperatively planned admissions and 10 were unexpectedly admitted postoperatively. The intraoperative and postoperative complication rate was 0.50% (29). We believe that ambulatory surgery is safe and efficient with proper patient selection and when the surgeon and the anesthetist have significant expertise.

Journal Article↗
PubMed1996

The consequences of engineering an extra disulfide bond in the Penicillium camembertii mono- and diglyceride specific lipase.

The extracellular lipase from Penicillium camembertii has unique substrate specificity restricted to mono- and diglycerides. The enzyme is a member of a homologous family of lipases from filamentous fungi. Four of these proteins, from the fungi Rhizomucor miehei, Humicola lanuginosa, Rhizopus delemar and P. camembertii, have had their structures elucidated by X-ray crystallography. In spite of pronounced sequence similarities the enzymes exhibit significant differences. For example, the thermostability of the P. camembertii lipase is considerably lower than that of the H. lanuginosa enzyme. Since only the P. camembertii enzyme lacks the characteristic long disulfide bridge, corresponding to Cys22-Cys268 in the H. lanuginosa lipase, we have engineered this disulfide into the former enzyme in the hope of obtaining a significantly more stable fold. The properties of the double mutant (Y22C and G269C) were assessed by a variety of biophysical techniques. The extra disulfide link was found to increase the melting temperature of the protein from 51 to 63 degrees C. However, no difference is observed under reducing conditions, indicating an intrinsic instability of the new disulfide. The optimal temperature for catalytic activity decreased by 10 degrees C and the optimum pH was shifted by 0.7 units to more acidic.

Base Sequence↗
PubMed1991

The savant syndrome and extrasensory perception.

D.A. Treffert, following B. Rimland, cited examples which he states show ESP to be occurring in certain autistic savant children. The evidence is questioned on the ground that it is hearsay, uncorroborated by independent scrutiny.

Aptitude↗