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Biomedical subjects

L Shea

Publications and source records attributed to L Shea.

At least 19 recordsLinked to original sources
PubMed1997

Mechanistic model of G-protein signal transduction. Determinants of efficacy and effect of precoupled receptors.

Tissue-specific characteristics (e.g. receptor number) and agonist-specific characteristics (e.g. agonist binding kinetics) play roles in determining cellular response. The roles that these characteristics play are quantified by models of signal transduction. We examined signal transduction through G-protein-linked receptors, using a model based on the collision coupling model but including interconverting receptor states and the precoupling of receptors with G-proteins prior to the addition of agonist. Reaction and diffusion of molecules within the plasma membrane were simulated using Monte Carlo techniques. The G-protein activation produced by our model was compared with that produced by the collision coupling model. We quantitatively examined how the parameters characteristic of the tissue and agonist determine the midpoint and maximal response of the dose-response curve. Activation through agonist binding to precoupled receptors can produce significantly higher activation rates than does collision coupling. Tissue and agonist characteristics have qualitatively similar effects but quantitatively distinct effects on activation for the two models. Using standard experimental techniques, it may be possible to exploit these differences to determine the mechanism of G-protein activation in a specific cell system. A quantitative comparison of model predictions with published data on the beta-adrenergic receptor system (Stickle D and Barber R, Mole Pharmacol 40: 276-288, 1991) also is presented.

Animals↗
PubMed1995

Cryosurgical ablation of the prostate.

A new surgical procedure, cryosurgical ablation of the prostate, offers patients with organ-confined prostate cancer another treatment option. The advantages of this cryosurgical technique are complete ablation of prostatic cancers without radical prostatectomy procedures, less blood loss, decreased hospital stays, reduced health care costs, and minimal associated morbidity. Some possible complications of cryosurgical ablation of the prostate procedures include incontinence, impotence, rectal freezing from inadequate monitoring of the freezing process, urethrocutaneous and urethrorectal fistula formations, and urethral tissue sloughing. The intraoperative nurse's prime responsibility is to monitor the subfreezing temperatures of the cryoprobes. Postoperatively, patients have only a few perineal incisions covered with sterile dressings and a suprapubic catheter. Most patients have minimal discomfort that is managed easily with opiate analgesics.

Cryosurgery↗
PubMed1993

Artificial urinary sphincters. Treatment for post-prostatectomy incontinence.

The artificial urinary sphincter offers patients who have incontinence due to loss of sphincter control the chance to regain control over urination. A well-planned diagnostic evaluation readily identifies patients who can benefit from this operative procedure. Placement of the artificial urinary sphincter is individualized to each patient's anatomic structure. Through the combined efforts of the surgeon, the urodynamics nurse, the surgical team, and the postoperative nursing staff, these patients experience a quick recovery and rapid return of control over bladder function.

Aged↗
PubMed1982

Diaphragmatic injury: a method for early diagnosis.

Traumatic diaphragmatic hernia, whether of blunt or penetrating etiology, is difficult to diagnose in the acute phase. The lesion is presently best diagnosed by chest X-ray, but only occasionally. Chest X-ray appears normal or nonspecific 25 to 50% of the time. For this reason, simple diagnostic technique using radiographic methodology available in emergency rooms was studied in animals in order to devise a way to diagnose this injury. Eight per cent diatrizoate meglumine and diatrizoate sodium (Renografin, Squibb) was placed into the chest or abdomen of animals with either 8-cm simulated blunt or 5-mm simulated penetrating injuries. The Renografin was infused by either a peritoneal lavage or thoracostomy catheter. Serial X-rays showed diagnostic rate of transdiaphragmatic leakage in 24 of 26 animals with blunt injury and seven of 16 animals with penetrating injury. There was no evidence of pleural, peritoneal, or pulmonary injury from the Renografin itself. It was concluded that the experimental technique may prove useful in screening or confirming traumatic diaphragmatic hernia during the acute or latent phases.

Animals↗
PubMed1975

Rubella and measles serosurvey among a nonurban pediatric population.

A serologic survey for rubella and measles immunity was conducted to determine the immunity levels among a nonurban, relatively isolated pediatric population. Among 1,273 students in grades kindergarten through 9, the overall susceptibility rate was 24.3% for rubella and 16.3% for measles. There was significant variation in susceptibility rates among the various grades and schools involved. The susceptibility rates were similar to those found for urban populations. The results indicated that vaccination efforts for the population have been partially successful, but additional effort was needed.

Adolescent↗
PubMed1975

Reye's syndrome: epidemiologic and viral studies, 1963-1974.

Fifty-eight children with Reye's syndrome (RS) confirmed by liver biopsy were treated at the University of Cincinnati between 1963 and 1974. Cases were clustered in the winter and spring with the peak in February and March. These coincided with the occurrence of influenza and, numerically, were associated more closely with influenza B than with influenza A. Six of the 58 cases were associated with chickenpox. Twenty-six children with RS were seen from 1963 to 1971, before the beginning of a systematic epidemiologic and virologic study. Viral infection was documented in either the patient or a contact in only 19% of those studied. Between 1971 and 1973, after the study was initiated, 16 cases of RS were diagnosed and viral infection was confirmed in 56% of these. In 1974, an epidemic of RS occurred during an influenza B epidemic and viral infection was found in either the patient or a contact in 81% of 16 cases. This study demonstrates that an association with viral infection can be proven in the majority of cases of RS when an intensive investigation is undertaken. During this study no significant environmental toxic exposures could be idenified. Most children had taken aspirin and other medications, and seven children had a history of excessive aspirin ingestion.

Adolescent↗