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Biomedical subjects

K Livingston

Publications and source records attributed to K Livingston.

At least 19 recordsLinked to original sources
PubMed2003

Polarization transfer in the 4He(e-->,e'p-->)3H reaction up to Q2=2.6 (GeV/c)2.

We have measured the proton recoil polarization in the 4He(e-->,e(')p-->)4H reaction at Q(2)=0.5, 1.0, 1.6, and 2.6 (GeV/c)(2). The measured ratio of polarization transfer coefficients differs from a fully relativistic calculation, favoring the inclusion of a medium modification of the proton form factors predicted by a quark-meson coupling model. In addition, the measured induced polarizations agree reasonably well with the fully relativistic calculation indicating that the treatment of final-state interactions is under control.

Journal Article↗
PubMed2003

Adherence and attrition with intermittent and continuous exercise in overweight women.

Few people are active to the levels recommended by Healthy People 2010. Intermittent exercise has been promoted as an exercise prescription which may enable more people to meet recommended guidelines. However, few data are available on intermittent exercise over the long-term. The purpose of the current study was to compare the effects of long-term (72 weeks) continuous (CON) and intermittent (INT) exercise on attrition and adherence in previously sedentary, moderately obese females. Participants were randomized to continuous walking at 60 to 75% of maximum aerobic capacity, 3 days per week, 30 minutes per session, or intermittent exercise for two 15-minute sessions, 5 days per week. Adherence was calculated as the number of sessions completed compared to the number of sessions prescribed. At 12-week intervals, attrition was calculated as the number of participants in the study compared to the total number of participants originally enrolled. For the participants who completed the study, body weight decreased for CON from 80.17 +/- 5.75 kg at baseline to 79.70 +/- 5.40 at 16 months (p < 0.05). For INT, body weight did not change from baseline (85.85 +/- 13.13 kg) to 16 months (85.05 +/- 12.90 kg). By design, INT walked significantly (p < 0.05) further (819 +/- 128 km) compared to CON (527 +/- 46 km). Attrition was 58% for both groups baseline to 72 weeks. However, attrition was greater for CON (38 %) compared to INT (16%) in the first 24 weeks. Adherence was excellent for both groups (> 83%) throughout the study. These results suggest that intermittent and continuous exercise both have considerable attrition rates within 72 weeks of exercise initiation; however, the pattern of attrition differs considerably. That is, it appears that intermittent exercise may reduce attrition in the first 24 weeks of an exercise program; however, attrition does not appear to be different than continuous exercise at 72 weeks.

Adult↗
PubMed1994

Endovascular embolization and surgical excision for the treatment of cerebellar and brain stem hemangioblastomas.

Hemangioblastomas are histologically benign tumors that comprise 7%-10% of all posterior fossa lesions in the adult. Treatment of these lesions is often complicated by significant vascularity and difficulty of surgical resection in sensitive neural tissue, especially when the tumor has a significant solid component. We report the combined use of endovascular embolization of feeding pedicles and subsequent operative resection in two patients with solid hemangioblastomas of the cerebellum and brain stem. Preoperative embolization facilitated operative excision in sensitive neural areas and allowed complete surgical resection of tumors involving the lateral brain stem and cervicomedullary junction. Goals of preoperative embolization are control of inaccessible arterial supply and reduction of tumor vascularity.

Adult↗
PubMed1994

Patient management, complications, and intensive care.

Advances in endovascular therapy have resulted in more acute care applications for more seriously ill patients. The use of standard neurological critical care techniques and specific preparations for minimizing the deleterious effects of ischemia facilitates the treatment of high-risk patients. Standardization of care also allows accurate comparison of newer endovascular and surgical advances.

Cerebrovascular Disorders↗
PubMed1992

Sensitivity of human glioma and brain cells to natural killer cell lysis. Effects of serum concentration, epidermal growth factor, and time in culture.

Using an in vitro monolayer natural killer (NK) cytolysis assay, the authors examined the effects of serum concentration and epidermal growth factor (EGF) on sensitivity to NK cytolysis. It was found that target cells cultured in high concentrations of serum (10% fetal bovine serum (FBS)) had higher cytotoxicity levels than those in low serum concentrations (0% to 0.5% FBS). Exposure of target cells to EGF had no effect on their sensitivity to NK cytolysis. Both glioma cell lines showed decreased NK cell sensitivity with longer times in culture. The results of cytofluorometric studies on these cell lines indicate that the differences in NK cell sensitivity may reflect the growth fraction of the target population and that a population with a higher proportion of cycling cells is more susceptible to lysis by NK cells. Whether it is possible to separate the proliferative rate of these cells from their NK cell sensitivity is unknown, but worthy of consideration.

Blood↗
PubMed1989

Intracranial trigeminal nerve rhabdomyoma/choristoma in a child: a case report and discussion of possible histogenesis.

Rhabdomyomas are rare tumors that usually arise within the heart, orocervical, or vulvovaginal regions. The cardiac tumors have a characteristic immature morphology, occur often in association with tuberous sclerosis, and are regarded as hamartomas rather than true neoplasms. The histogenesis of the extracardiac tumors and their true neoplastic nature are matters of controversy. We report the first case of a rhabdomyoma located inside the cranium. The intimate association with the mandibular division of the trigeminal nerve, the normal embryogenesis of the craniofacial muscles, and animal homograft and xenograft experiments provide a framework for considering this tumor, and possibly other rhabdomyomas, as a choristoma/hamartoma rather than a true neoplasm.

Child, Preschool↗
PubMed1981

Effect of inflammatory arthritis on dexamethasone receptors in phagocytes--a possible role for plasma factors.

Synovial tissue cells from patients with seropositive rheumatoid arthritis bind dexamethasone in a similar fashion to the classical steroid receptors on other cells. In contrast, synovial fluid cells and blood PMNLs from these patients bind dexamethasone with much reduced affinity. Some component of plasma may interfere with the binding of dexamethasone to its receptor.

Arthritis, Rheumatoid↗
PubMed1979

The effect of procaine hydrochloride and diazepam, separately or in combination, on cortico-generalized kindled seizures.

The effects of cortically kindled seizure responses of procaine hydrochloride, diazepam and combinations of these two drugs were tested in this study. The cortex was stimulated until seizure responses developed past the focal stage (accompanied primarily by brief tonic convulsions) to the cortico-generalized stage (accompanied, typically, by an early brief tonus followed by a longer clonic seizure that is characteristic of subcortically triggered seizures). Diazepam was found to block the generalized component of the cortico-generalized electrographic and motor seizure leaving the tonus only slightly suppressed. Procaine blocked the tonus leaving the clonic seizure and discharge that is characteristic of the generalized response relatively intact. Combinations of half doses of the two drugs completely blocked all electrographic and motor seizure responses in about half the animals. The remaining animals had a very brief discharge with no convulsive responses.

Animals↗