Search PubMed⌕ Search

Biomedical subjects

R Turner

Publications and source records attributed to R Turner.

At least 343 records · Page 19Linked to original sources
PubMedDate not supplied

Imaging of diffusion and microcirculation with gradient sensitization: design, strategy, and significance.

Recent developments in the use of magnetic resonance (MR) to measure and image diffusion and blood microcirculation ("perfusion") are summarized. After a brief description of the effects of diffusion and perfusion on the MR signal, the different methods (conventional spin-echo, stimulated-echo, gradient-echo, and echo-planar imaging) that have been proposed and used to image and measure diffusion and perfusion by gradient sensitization are presented, along with their advantages and limitations. The difficulties of diffusion/perfusion imaging related to both hardware and software are then discussed. Special attention is given to specific problems encountered with in vivo studies and data analysis. Finally, the potential biologic and clinical applications are outlined, and some examples are presented.

Brain↗
PubMedDate not supplied

The impact of behavior and addiction on psychological models of cigarette and alcohol use during pregnancy.

This prospective study of 241 women investigated the impact of past behavior and psychological factors on cigarette and alcohol use during pregnancy. Smokers' cigarette use was compared with their alcohol consumption during pregnancy, and drinking among smokers was compared with that of nonsmokers. Only prior smoking directly predicted smokers' cigarette use later in pregnancy, whereas smokers' alcohol use was related to both their previous drinking and their drinking self-efficacy. Among nonsmokers, neither drinking before nor early in pregnancy was related to alcohol use later in pregnancy; only subjects' self-efficacy and their beliefs about the consequences of drinking during pregnancy predicted their subsequent alcohol use. These results are consistent with the notion that greater addictive potential lessens the direct impact of psychological factors on substance use during pregnancy. Further implications of these findings for interventions and other health-related behaviors are also discussed.

Adolescent↗
PubMedDate not supplied

Pharmacokinetic interaction of BCNU and misonidazole in humans.

Although considerable laboratory in vitro and in vivo evidence is now available suggesting that misonidazole (MISO) enhances chemotherapy tumor responses, experience with human tumors is limited. Further, the mechanism of this enhancement is not definitely known. One possible mechanism is that MISO alters the pharmacokinetics of the chemotherapeutic agent, vice versa or both. We studied a group of patients with recurrent malignant gliomas, following radiotherapy. After proven recurrence, they were treated with i.v. BCNU in combination with oral MISO in an 8 week cycle. Our aims were: 1. To obtain a second remission; 2. To assess the toxicity of this combination; 3. To assess the plasma pharmacokinetics of each drug alone and in combination. Six patients entered the protocol. Four of six patients obtained either a partial or subpartial response. Prolonged moderate myelosuppression was observed in 2/6 patients after 3 cycles; 2/6 patients experienced seizures after the first cycle of chemotherapy for the first time in the course of their disease. The plasma pharmacokinetic data indicates no evidence of a MISO-BCNU drug interaction.

Bone Marrow Diseases↗
PubMedDate not supplied

Magnetic resonance imaging methods for study of human brain function and their application at high magnetic field.

Magnetic resonance imaging (MRI) sequences are finding a new application in the study of human brain function by monitoring localized changes in signal intensity which accompany neuronal activity. These sequences can be sensitized to changes in cerebral blood volume, cerebral blood flow, and blood oxygenation, all of which reflect aspects of neuronal activity in the brain. Many of these experiments benefit from being implemented at a higher magnetic field strength than conventional MRI. An overview of these techniques is presented, and examples of their use are given.

Blood Volume↗
PubMedDate not supplied

MR color mapping of myelin fiber orientation.

Diffusion of water in brain white matter has been shown to be anisotropic: Water mobility is lower when measured perpendicular to the fiber direction rather than parallel to it. This feature was used to produce images of the myelin fiber orientation. Coronal and sagittal MR diffusion images were obtained in volunteers using an echo-planar imaging sequence sensitized to molecular diffusion in perpendicular directions. Color-coded images of myelin orientation were then generated by combining these images together. The orientation of the white matter tracts was found to be in excellent agreement with known anatomy. Myelin fiber orientation mapping may offer a new perspective to evaluate white matter disorders.

Algorithms↗
PubMedDate not supplied

Randomized comparison trial of the RIK and the Nimbus 3 mattresses.

A randomized comparison trial was carried out at Queen's Hospital, Burton-on-Trent, to compare patient outcomes on the RIK mattress (KCI) and the Nimbus 3 mattress (Huntleigh Healthcare). One hundred and fifty-eight patients, who were assessed to be at particular risk of development of pressure ulcers using the Waterlow score (85 on RIK mattress, 83 on Nimbus), completed the trial. There were no statistically significant differences in baseline parameters at recruitment or pressure ulcer progress. Lack of difference can be as useful as evidence of superiority. Other factors such as nursing interventions required accessible equipment, and costs are important when making equipment choices. For a significant proportion of patients, a static (RIK) mattress can be as effective as an active (Nimbus 3) mattress for management of pressure ulcers.

Aged↗
PubMedDate not supplied

Ordinary people.

Explore the source record for details and available documents.

Female↗
PubMedDate not supplied

[Comparison of laparoscopic ultrasound and cholangiography during laparoscopic cholecystectomies. Results of a prospective study].

AIM: Prospective evaluation of the results of laparoscopic ultrasound and cholangiography to investigate choledocholithiasis and detect variations in biliary anatomy during laparoscopic cholecystectomies. METHODS: The biliary trees of 600 patients who underwent laparoscopic cholecystectomy were routinely explored by laparoscopic ultrasound and cholangiography. RESULTS: Laparoscopic ultrasound was performed in all 600 cases. Cholangiography was performed in 498 (83%). Laparoscopic ultrasound required less time than cholangiography: 10.2 minutes versus 17.9 minutes (P=0.0001). Common bile duct stones were detected intraoperatively in 40 cases (7%). Both methods were equally effective. The sensitivity of laparoscopic ultrasound was 80% and its specificity 99%. For cholangiography these values were 75% and 98% respectively. For laparoscopic ultrasound, false positives and false negatives were noted in the first 45 cases of individual trainees. Nevertheless, cholangiography showed 30 anatomical anomalies and laparoscopic ultrasound only 15. CONCLUSION: Laparoscopic ultrasound can be performed rapidly and in all cases. Results are comparable to cholangiography in the detection of common duct stones. Individual training is necessary to optimize efficacy. Anatomical anomalies are often missed.

Adult↗
PubMedDate not supplied

Magnetic resonance imaging of brain function.

New techniques for imaging of brain function are described, which utilize magnetic resonance imaging. Echo-planar imaging (EPI), the preferred method, is introduced and technical issues are discussed. Two recent approaches for measurement of blood flow are explained: contrast agent bolus tracking and black blood perfusion. An intrinsic contrast technique, which utilizes the paramagnetism of deoxyhemoglobin, is presented. Results from experiments on functional imaging of the human brain are shown, and the specific advantages of MRI for this purpose are discussed.

Animals↗
PubMedDate not supplied

The use of modified human umbilical cord vein in femoral popliteal reconstruction.

Glutaraldehyde-tanned human umbilical cord veins were employed for reconstruction of the femoral popliteal segment in 80 instances. The primary indication for surgery was imminent loss of limb. The cumulative patency to 20 months was 84.8 percent. The primary mechanism for graft failure was thrombosis usually due to progressive atherosclerosis of the distal circulation (6 cases). There were no instances of infection, dilatation of the graft or aneurysm formation. The data indicate that the results obtained when the glutaraldehyde-tanned umbilical vein in femoral popliteal location are comparable and perhaps even superior to those obtained with the saphenous vein. This suggests that this graft material will be applicable as avascular prosthesis in many instances and will provide for limb salvage and function in patients who face potential loss of limb.

Aged↗