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B Young

Publications and source records attributed to B Young.

At least 55 records · Page 3Linked to original sources
PubMed2000

The effects of internal radiation exposure on cancer mortality in nuclear workers at Rocketdyne/Atomics International.

We examined the effects of chronic exposure to radionuclides, primarily uranium and mixed-fission products, on cancer mortality in a retrospective cohort study of workers enrolled in the radiation-monitoring program of a nuclear research and development facility. Between 1950 and 1994, 2,297 workers were monitored for internal radiation exposures, and 441 workers died, 134 (30.4%) of them from cancer as the underlying cause. We calculated internal lung-dose estimates based on urinalysis and whole-body and lung counts reported for individual workers. We examined cancer mortality of workers exposed at different cumulative lung-dose levels using complete risk-set analysis for cohort data, adjusting for age, pay type, time since first radiation monitored, and external radiation. In addition, we examined the potential for confounding due to chemical exposures and smoking, explored whether external radiation exposure modifies the effects of internal exposure, and estimated effects after excluding exposures likely to have been unrelated to disease onset. Dose-response relations were observed for death from hemato- and lymphopoietic cancers and from upper aerodigestive tract cancers, adjusting for age, time since first monitored, pay type, and external (gamma) radiation dose. No association was found for other cancers, including cancers of the lung. Despite the small number of exposed deaths from specific cancer types and possible bias due to measurement error and confounding, the positive findings and strong dose-response gradients observed suggest carcinogenic effects of internal radiation to the upper aerodigestive tract and the blood and lymph system in this occupational cohort. However, causal inferences require replication of our results in other populations or confirmation with an extended follow-up of this cohort.

California↗
PubMed2000

Gamma knife radiosurgery as a primary treatment for prolactinomas.

OBJECT: The purpose of this study was to estimate the efficacy of gamma knife radiosurgery (GKS) in controlling tumor growth and endocrinopathy associated with prolactinomas. METHODS: Between 1993 and 1997, 164 of 469 patients with pituitary adenomas treated by GKS harbored prolactinomas. The dose to the tumor margin ranged from 9 to 35 Gy (mean 31.2 Gy), and the visual pathways were exposed to a dose of less than 10 Gy. The mean tumor diameter was 13.4 mm. The mean follow-up time for 128 cases was 33.2 months (range 6-72 months). Tumor control was observed in all but two patients who underwent surgery 18 and 36 months, respectively, after GKS. Clinical cure was achieved in 67 cases. Clinical improvement was noted with a decrease in the hyperprolactinemia after GKS. Nonetheless, in 31 (29%) of 108 patients who were followed for more than 2 years no improvement in serum prolactin levels was demonstrated, although this could be normalized by bromocriptine administration after treatment. Nine infertile women became pregnant 2 to 13 months after GKS and all gave birth to normal children. There was no visual deterioration related to GKS. Five women experienced premature menopause. In these patients there was subtotal disappearance of the tumor and an empty sella developed. CONCLUSIONS: Gamma knife radiosurgery as a primary treatment for prolactinomas can be safe and effective both for controlling tumor growth and for normalization of prolactin hypersecretion. A higher margin dose (> or = 30 Gy) seemed to be associated with a better clinical outcome. Gamma knife radiosurgery may make prolactinomas more sensitive to the bromocriptine.

Humans↗
PubMed2000

Overexpression of cyclin A and cyclin B1 proteins in astrocytomas.

BACKGROUND: Cyclins are proteins that are expressed during the progression of a normal cell through the cell cycle. In a number of cancers, overexpression of cyclin A and cyclin B1 proteins has been reported, and in some instances the levels of expression correlated well with the grades of malignancy. The expression of cyclin A and cyclin B1 proteins in astrocytoma may be linked to the histologic grade or proliferative activities. OBJECTIVE: To study the expression of cyclin A and cyclin B1 proteins in astrocytomas and correlate the labeling indices (LIs) of cyclin A and cyclin B1 with histologic grade and Ki-67 LI. DESIGN: The surgical biopsy specimens from 65 adults with astrocytomas were reviewed and divided into grades based on the World Health Organization system. The paraffin sections were immunostained using primary antibodies against Ki-67, cyclin A, and cyclin B1. The LIs of these astrocytomas for the 3 different antibodies were determined by computerized image analysis. RESULTS: The cyclin A LI showed good correlation with astrocytoma grade and Ki-67 LI. Both the nuclear and cytoplasmic cyclin B LIs correlated well with the tumor grade but showed poor correlation with Ki-67 LI. CONCLUSIONS: This study suggests that although both cyclin A and B protein expression are related to the grade of malignancy in astrocytomas, cyclin A levels more generally reflect the proliferative state of these tumors. We also provide indirect evidence that cyclin B1 is associated with the aberrant progression through the G2-M phase checkpoint in astrocytomas.

Astrocytoma↗
PubMed1999

A multi-institutional analysis of complication outcomes after arteriovenous malformation radiosurgery.

PURPOSE: To better understand radiation complications of arteriovenous malformation (AVM) radiosurgery and factors affecting their resolution. METHODS AND MATERIALS: AVM patients (102/1255) who developed neurological sequelae after radiosurgery were studied. The median AVM marginal dose (Dmin) was 19 Gy (range: 10-35). The median volume was 5.7 cc (range: 0.26-143). Median follow-up was 34 months (range: 9-140). RESULTS: Complications consisted of 80/102 patients with evidence of radiation injury to the brain parenchyma (7 also with cranial nerve deficits, 12 also with seizures, 5 with cyst formation), 12/102 patients with isolated cranial neuropathies, and 10/102 patients with only new or worsened seizures. Severity was classified as minimal in 39 patients, mild in 40, disabling in 21, and fatal in 2 patients. Symptoms resolved completely in 42 patients for an actuarial resolution rate of 54% +/- 7% at 3 years post-onset. Multivariate analysis identified significantly greater symptom resolution in patients with no prior history of hemorrhage (p = 0.01, 66% vs. 41%), and in patients with symptoms of minimal severity: headache or seizure as the only sequelae of radiosurgery (p < 0.0001, 88% vs. 34%). CONCLUSION: Late sequelae of radiosurgery manifest in varied ways. Further long-term studies of these problems are needed that take into account symptom severity and prior hemorrhage history.

Adrenal Cortex Hormones↗
PubMed1999

Review of methods to predict and detect atrial fibrillation in post-cardiac surgery patients.

Atrial fibrillation (AF) is the most common sustained arrhythmia after cardiac surgery. Postoperative AF is known to substantially lengthen hospital stay and affect patient recovery. Identification of those at risk of developing AF after surgery and early detection of AF during recovery would be extremely helpful in effective management of these patients, including targeting prophylactic therapy to prevent AF in high-risk patients. In this communication, diagnostic methods to identify those at risk of developing AF after surgery and early identification of AF before, during, and after surgery have been reviewed. Signal-averaged P wave analysis, done before surgery, identifies patients who are likely to develop AF during recovery. When combined with low ejection fraction, signal-averaged P wave can discriminate those who develop AF from those who do not. During recovery, AF can be detected early either from a detailed analysis of atrial activity in a 10-second electrocardiogram or an analysis of R-to-R intervals from an extended rhythm strip (1 minute or longer). Analysis of the 10-second electrocardiogram includes median QRST subtraction from rhythm data and detection and analysis of atrial signals in the resulting residual. AF is detected from extended rhythm strips by using a statistical model to identify the presence of characteristic irregular patterns of R-to-R intervals.

Atrial Fibrillation↗
PubMed1999

Arachidonic acid-induced oxidative injury to cultured spinal cord neurons.

Spinal cord trauma can cause a marked release of free fatty acids, in particular, arachidonic acid (AA), from cell membranes. Free fatty acids, and AA by itself, may lead to secondary damage to spinal cord neurons. To study this hypothesis, cultured spinal cord neurons were exposed to increasing concentrations of AA (0.01-10 microM). AA-induced injury to spinal cord neurons was assessed by measurements of cellular oxidative stress, intracellular calcium levels, activation of nuclear factor-KB (NF-kappaB), and cell viability. AA treatment increased intracellular calcium concentrations and decreased cell viability. Oxidative stress increased significantly in neurons exposed to 1 and 10 microM AA. In addition, AA treatment activated NF-kappaB and decreased levels of the inhibitory subunit, IKB. It is interesting that manganese superoxide dismutase protein levels and levels of intracellular total glutathione increased in neurons exposed to this fatty acid for 24 h, consistent with a compensatory response to increased oxidative stress. These results strongly support the hypothesis that free fatty acids contribute to the tissue injury observed following spinal cord trauma.

Animals↗
PubMed1999

Sterilization and disinfection in general practice in Northern Ireland.

In view of the recent trend towards more minor surgery being carried out in general practice we decided to conduct a postal survey to assess the level of knowledge of sterilization and disinfection and the use of benchtop sterilizers in general practice in Northern Ireland. The survey, of all 366 practices in the Province, was carried out in January/March 1998. One hundred and eleven (30%) completed questionnaires were returned. All practices performed at least one of a range of procedures requiring sterilization or disinfection, e.g., minor surgery 95%, cervical smear taking 98%, syringing of ears 98%. Only 76% of practices had a benchtop sterilizer and 39% did not have access to a sterile supply department (SSD); 32% of the latter had no desire to utilize such a service. Only 25% and 34% correctly identified the Medical Devices Agency (MDA) definitions of sterilization and disinfection respectively. The MDA Device Bulletin on benchtop sterilizers had been read by only 26% of respondents. There was an 86% interest in attending a workshop on sterilization and disinfection. The concepts and practice of sterilization and disinfection appear not to be clearly understood. We conclude that resources must be identified to provide appropriate education in this important area for primary care staff.

Ambulatory Surgical Procedures↗
PubMed1999

Piloting the Institute of Medical Illustrators and Glasgow Caledonian University BSc in medical illustration conversion course.

Diplomates of the Institute of Medical Illustrators (IMI) have a route to converting their existing qualification to a Bachelor of Science (BSc) in Medical Illustration. The experience of a pilot group who undertook this course is described, and advice for potential students is proposed. Additional comments based on the findings and recommendations of the Scrutiny Panel, who have a role in project approval and assessment, have also been included to assist students undertaking the conversion course. Students of this pilot group found the experience of undertaking the conversion course a rewarding exercise, although the effort required to successfully pass should not be underestimated.

Humans↗
PubMed1999

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Journal Article↗
PubMed1999

Postpyloric enteral feeding costs for patients with severe head injury: blind placement, endoscopy, and PEG/J versus TPN.

This study describes the advantages and disadvantages of several forms of enteral nutrition for patients with severe head injury (Glasgow Coma Scale Score [GCS], <12). Included in the study are nasoenteric nutrition delivery using blind, endoscopic, percutaneous endoscopic gastrostomy (PEG) and PEG with jejeunostomy (PEG/J), and open jejeunostomy tube placement methods. These methods are compared with parenteral delivery of nutrition. The study constituted a retrospective analysis of the success rate of early enteral feedings by blind, endoscopic PEG and PEG/J and by open jejeunostomy placement of small-bowel feeding tubes for 57 patients with severe head injury. The delivery cost of enteral nutrition per intensive care unit day was compared to the delivery cost of parenteral nutrition per intensive care unit day in the same group of patients. Fifty-three percent of patients were adequately maintained nutritionally with nasoenteric delivery alone and did not require parenteral feeding. The average number of days for initiation of either enteral or parenteral feedings was 1.8 +/- 0.2 days from injury [standard error of mean (SEM); range, 0-10 days]. An average of 3.3 days (range, 0-23 days) was required for feeding tube placement in all patients. For 70% of patients, tube placement was completed within 48 h after injury. Full-strength, full-rate enteral feedings were achieved by a mean of 4.9 days after injury. A total of 128 feeding tubes were placed while the patients were in the intensive care unit (ICU; 2.2 +/- 0.2 tubes per patient). Blind placement of feeding tubes into the small bowel was rarely achieved without repositioning. Endoscopic tube placement into the duodenum was achieved in 50% of patients, into the jejunum for 33% of patients, and into the stomach for 18% of patients. While in the intensive care unit, patients received an average of 77 +/- 2% of their measured energy expenditure (range, 57-114%). Eleven percent of patients experienced severe gastrointestinal problems. Other problems were associated with the inability to achieve or maintain access: dislodged tubes (30%), clogged or kinked tubes (21%), and mechanical access problems (7 %). Seventy-one percent of patients in barbiturate coma were able to tolerate early nasoenteric feedings. Aspiration pneumonitis occurred equally among patients fed nasogastrically and those fed nasoenterically. The overall aspiration rate was 14%. The cost of acute enteral feeding was $170 per day and that for parenteral feeding, $308 per day. We conclude that blind transpyloric feeding tube placement is difficult to achieve in patients with severe head injury; endoscopically guided placement is a better option. Endoscopic feeding tube placement most consistently allows for early enteral nutritional support in severe head injured patients. Limitations include the inability to establish and/or maintain enteral access, increased intracranial pressure, unstable cervical spinal injuries, facial fractures, and dedication of the physician to tube placement and monitoring.

Adult↗
PubMed1999

Versican enhances locomotion of astrocytoma cells and reduces cell adhesion through its G1 domain.

Versican is a large extracellular proteoglycan and is expressed in a variety of tissues including the central nervous system. A malignant astrocytoma cell line U87 with high motility expressed a higher level of versican than another malignant astrocytoma cell line U343 with lower motility. We observed that the U87 cells were less adherent to tissue culture plates than the U343 cells. To investigate the role of versican in astrocytoma cell migration, we generated recombinant products of a mini-versican construct expressed in COS-7 cells. We found that the mini-versican products enhanced astrocytoma cell migration. Furthermore, enhanced migration was promoted by the G1 domain but not the G3 domain of versican. We introduced culture medium containing products of the mini-versican, the G1, and the G3 constructs separately into the astrocytoma cell lines U87 and U343. The mini-versican and the G1 construct, but not the G3 construct, were shown to reduce astrocytoma cell adhesion. The present data suggest that versican exerts its effect on astrocytoma cell migration and adhesion through the G1 domain.

Astrocytoma↗
PubMed1999

Aberrant expression of cyclin A and cyclin B1 proteins in oral carcinoma.

Cyclins play an important role in regulating the passage of dividing cells through critical checkpoints in the cell cycle. Aberrant expression of cyclin proteins has been found in a number of human cancers, including carcinomas of the head and neck, where amplification of the cyclin D1 gene is a common finding. The objective of this study was to examine cell cycle kinetics in oral carcinomas by determining the expression of the S phase protein cyclin A and the M phase protein cyclin B1. Routinely processed tissue sections of 50 oral squamous cell carcinomas from the floor of the mouth were stained by immunohistochemistry for cyclin A, cyclin B1 and Ki-67 proteins. Ten specimens of normal epithelium from the floor of the mouth were used as controls. The number of cells showing nuclear staining for cyclin A, cyclin B1 and Ki-67 proteins was determined by computer image analysis. There were 17 well-differentiated, 25 moderately differentiated and 8 poorly differentiated tumours. Mean counts for cyclin A (29.50+/-4.10, mean+/-95% CI), cyclin B1 (2.05+/-0.30) and Ki-67 (49.46+/-5.91) proteins in the carcinomas were significantly higher than counts for the normal epithelial controls (cyclin A: 9.30+/-1.72; cyclin B1: 1.01+/-0.36; Ki-67: 17.40+/-4.17). For cyclin A, cyclin B1 and Ki-67, mean staining scores for all tumour grades were significantly higher than controls. There was a strong correlation between Ki-67 and cyclin A scores in all tumour groups (r2=0.68); however, the correlations between cyclin B1 and cyclin A scores (r2=0.35) and between cyclin B1 and Ki-67 scores (r2= 0.39) were weak. We conclude that there is overexpression of cyclin A and cyclin B1 proteins in oral carcinoma. Furthermore, the poor correlations for cyclin B1 scores with other cell cycle indices suggest that there may be aberrant cell cycle progression at the G2/M checkpoint in oral carcinomas.

Carcinoma, Squamous Cell↗
PubMed1999

An investigation of hypomagnesemia among ambulatory urban African Americans.

BACKGROUND: Magnesium represents the fourth most abundant cation in the body and plays an integral role in intracellular metabolism. Although magnesium deficiency states have been associated with a variety of medical conditions, the prevalence of hypomagnesemia has not been well studied, particularly in ambulatory settings. METHODS: We performed a period prevalence study using 120 patients seen for routine medical care at an urban family medicine center. Chart reviews were completed for these subjects. We used univariate and multivariate analyses to correlate magnesium levels with demographic and clinical factors. RESULTS: There was a 20% overall prevalence of hypomagnesemia among this predominantly female, African American population. The prevalence of hypomagnesemia was greatest among patients with a history of alcoholism (odds ratio [OR] = 6.00; 95% confidence interval [CI], 1.41-26.1) and among those having 1 or more of the following medical conditions: diabetes, hyperlipidemia, hypertension, renal disease, and asthma (OR = 4.69; 95% CI, 1.37-17.65). CONCLUSIONS: The prevalence of hypomagnesemia among patients from this urban minority community exceeds that reported in previous studies of the general population. This may be reflective of greater comorbidity, diminished nutritional status, or poorer overall health among patients from this community. The association between hyperlipidemia and magnesium deficiency warrants further investigation.

Adult↗
PubMed1999

Viral kinetics: implications for treatment.

Increasing knowledge of the principles of viral dynamics in HIV infection has dramatically changed our understanding of the disease. Basic concepts of viral kinetics and implications for the treatment of HIV-infected persons are reviewed.

Anti-HIV Agents↗
PubMed1998

Postoperative radiotherapy in the treatment of single metastases to the brain: a randomized trial.

CONTEXT: For the treatment of a single metastasis to the brain, surgical resection combined with postoperative radiotherapy is more effective than treatment with radiotherapy alone. However, the efficacy of postoperative radiotherapy after complete surgical resection has not been established. OBJECTIVE: To determine if postoperative radiotherapy resulted in improved neurologic control of disease and increased survival. DESIGN: Multicenter, randomized, parallel group trial. SETTING: University-affiliated cancer treatment facilities. PATIENTS: Ninety-five patients who had single metastases to the brain that were treated with complete surgical resections (as verified by postoperative magnetic resonance imaging) between September 1989 and November 1997 were entered into the study. INTERVENTIONS: Patients were randomly assigned to treatment with postoperative whole-brain radiotherapy (radiotherapy group, 49 patients) or no further treatment (observation group, 46 patients) for the brain metastasis, with median follow-up of 48 weeks and 43 weeks, respectively. MAIN OUTCOME MEASURES: The primary end point was recurrence of tumor in the brain; secondary end points were length of survival, cause of death, and preservation of ability to function independently. RESULTS: Recurrence of tumor anywhere in the brain was less frequent in the radiotherapy group than in the observation group (9 [18%] of 49 vs 32 [70%] of 46; P<.001). Postoperative radiotherapy prevented brain recurrence at the site of the original metastasis (5 [10%] of 49 vs 21 [46%] of 46; P<.001) and at other sites in the brain (7 [14%] of 49 vs 17 [37%] of 46; P<.01). Patients in the radiotherapy group were less likely to die of neurologic causes than patients in the observation group (6 [14%] of 43 who died vs 17 [44%] of 39; P=.003). There was no significant difference between the 2 groups in overall length of survival or the length of time that patients remained functionally independent. CONCLUSIONS: Patients with cancer and single metastases to the brain who receive treatment with surgical resection and postoperative radiotherapy have fewer recurrences of cancer in the brain and are less likely to die of neurologic causes than similar patients treated with surgical resection alone.

Adult↗
PubMed1998

A mixture model for sucking patterns of breast-fed infants.

Previous studies of sucking patterns have mainly been on bottle-fed babies and have assumed that the babies' sucks occur within bursts separated by gaps of predetermined minimum length which is fixed over the feed. This study considers babies that are breast-fed, a more complex and natural process than bottle-feeding, and develops a more sophisticated model for the pattern of bursts and gaps which allows the parameters of the process to vary over the feed. We consider data from four breast feeds of each of 32 babies. We develop a two-component mixture model based on an underlying Markov chain model for the switching between bursts and gaps. We use the model to provide summary statistics for each feed and give estimates of the normal range of each of the model's parameters.

Breast Feeding↗